1 /*
2 * Copyright (c) 1999, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 // no precompiled headers
26 #include "classfile/classLoader.hpp"
27 #include "classfile/systemDictionary.hpp"
28 #include "classfile/vmSymbols.hpp"
29 #include "code/icBuffer.hpp"
30 #include "code/vtableStubs.hpp"
31 #include "compiler/compileBroker.hpp"
32 #include "compiler/disassembler.hpp"
33 #include "interpreter/interpreter.hpp"
34 #include "jvm_linux.h"
35 #include "memory/allocation.inline.hpp"
36 #include "memory/filemap.hpp"
37 #include "mutex_linux.inline.hpp"
38 #include "oops/oop.inline.hpp"
39 #include "os_share_linux.hpp"
40 #include "prims/jniFastGetField.hpp"
41 #include "prims/jvm.h"
42 #include "prims/jvm_misc.hpp"
43 #include "runtime/arguments.hpp"
44 #include "runtime/extendedPC.hpp"
45 #include "runtime/globals.hpp"
46 #include "runtime/interfaceSupport.hpp"
47 #include "runtime/init.hpp"
48 #include "runtime/java.hpp"
49 #include "runtime/javaCalls.hpp"
50 #include "runtime/mutexLocker.hpp"
51 #include "runtime/objectMonitor.hpp"
52 #include "runtime/orderAccess.inline.hpp"
53 #include "runtime/osThread.hpp"
54 #include "runtime/perfMemory.hpp"
55 #include "runtime/sharedRuntime.hpp"
56 #include "runtime/statSampler.hpp"
57 #include "runtime/stubRoutines.hpp"
58 #include "runtime/thread.inline.hpp"
59 #include "runtime/threadCritical.hpp"
60 #include "runtime/timer.hpp"
61 #include "services/attachListener.hpp"
62 #include "services/memTracker.hpp"
63 #include "services/runtimeService.hpp"
64 #include "utilities/decoder.hpp"
65 #include "utilities/defaultStream.hpp"
66 #include "utilities/events.hpp"
67 #include "utilities/elfFile.hpp"
68 #include "utilities/growableArray.hpp"
69 #include "utilities/vmError.hpp"
70
71 // put OS-includes here
72 # include <sys/types.h>
73 # include <sys/mman.h>
74 # include <sys/stat.h>
75 # include <sys/select.h>
76 # include <pthread.h>
77 # include <signal.h>
78 # include <errno.h>
79 # include <dlfcn.h>
80 # include <stdio.h>
81 # include <unistd.h>
82 # include <sys/resource.h>
83 # include <pthread.h>
84 # include <sys/stat.h>
85 # include <sys/time.h>
86 # include <sys/times.h>
87 # include <sys/utsname.h>
88 # include <sys/socket.h>
89 # include <sys/wait.h>
90 # include <pwd.h>
91 # include <poll.h>
92 # include <semaphore.h>
93 # include <fcntl.h>
94 # include <string.h>
95 # include <syscall.h>
96 # include <sys/sysinfo.h>
97 # include <gnu/libc-version.h>
98 # include <sys/ipc.h>
99 # include <sys/shm.h>
100 # include <link.h>
101 # include <stdint.h>
102 # include <inttypes.h>
103 # include <sys/ioctl.h>
104
105 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
106
107 #ifndef _GNU_SOURCE
108 #define _GNU_SOURCE
109 #include <sched.h>
110 #undef _GNU_SOURCE
111 #else
112 #include <sched.h>
113 #endif
114
115 // if RUSAGE_THREAD for getrusage() has not been defined, do it here. The code calling
116 // getrusage() is prepared to handle the associated failure.
117 #ifndef RUSAGE_THREAD
118 #define RUSAGE_THREAD (1) /* only the calling thread */
119 #endif
120
121 #define MAX_PATH (2 * K)
122
123 #define MAX_SECS 100000000
124
125 // for timer info max values which include all bits
126 #define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF)
127
128 #define LARGEPAGES_BIT (1 << 6)
129 ////////////////////////////////////////////////////////////////////////////////
130 // global variables
131 julong os::Linux::_physical_memory = 0;
132
133 address os::Linux::_initial_thread_stack_bottom = NULL;
134 uintptr_t os::Linux::_initial_thread_stack_size = 0;
135
136 int (*os::Linux::_clock_gettime)(clockid_t, struct timespec *) = NULL;
137 int (*os::Linux::_pthread_getcpuclockid)(pthread_t, clockid_t *) = NULL;
138 Mutex* os::Linux::_createThread_lock = NULL;
139 pthread_t os::Linux::_main_thread;
140 int os::Linux::_page_size = -1;
141 const int os::Linux::_vm_default_page_size = (8 * K);
142 bool os::Linux::_is_floating_stack = false;
143 bool os::Linux::_is_NPTL = false;
144 bool os::Linux::_supports_fast_thread_cpu_time = false;
145 const char * os::Linux::_glibc_version = NULL;
146 const char * os::Linux::_libpthread_version = NULL;
147 pthread_condattr_t os::Linux::_condattr[1];
148
149 static jlong initial_time_count=0;
150
151 static int clock_tics_per_sec = 100;
152
153 // For diagnostics to print a message once. see run_periodic_checks
154 static sigset_t check_signal_done;
155 static bool check_signals = true;
156
157 static pid_t _initial_pid = 0;
158
159 /* Signal number used to suspend/resume a thread */
160
161 /* do not use any signal number less than SIGSEGV, see 4355769 */
162 static int SR_signum = SIGUSR2;
163 sigset_t SR_sigset;
164
165 /* Used to protect dlsym() calls */
166 static pthread_mutex_t dl_mutex;
167
168 // Declarations
169 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time);
170
171 // utility functions
172
173 static int SR_initialize();
174
175 julong os::available_memory() {
176 return Linux::available_memory();
177 }
178
179 julong os::Linux::available_memory() {
180 // values in struct sysinfo are "unsigned long"
181 struct sysinfo si;
182 sysinfo(&si);
183
184 return (julong)si.freeram * si.mem_unit;
185 }
186
187 julong os::physical_memory() {
188 return Linux::physical_memory();
189 }
190
191 ////////////////////////////////////////////////////////////////////////////////
192 // environment support
193
194 bool os::getenv(const char* name, char* buf, int len) {
195 const char* val = ::getenv(name);
196 if (val != NULL && strlen(val) < (size_t)len) {
197 strcpy(buf, val);
198 return true;
199 }
200 if (len > 0) buf[0] = 0; // return a null string
201 return false;
202 }
203
204
205 // Return true if user is running as root.
206
207 bool os::have_special_privileges() {
208 static bool init = false;
209 static bool privileges = false;
210 if (!init) {
211 privileges = (getuid() != geteuid()) || (getgid() != getegid());
212 init = true;
213 }
214 return privileges;
215 }
216
217
218 #ifndef SYS_gettid
219 // i386: 224, ia64: 1105, amd64: 186, sparc 143
220 #ifdef __ia64__
221 #define SYS_gettid 1105
222 #else
223 #ifdef __i386__
224 #define SYS_gettid 224
225 #else
226 #ifdef __amd64__
227 #define SYS_gettid 186
228 #else
229 #ifdef __sparc__
230 #define SYS_gettid 143
231 #else
232 #error define gettid for the arch
233 #endif
234 #endif
235 #endif
236 #endif
237 #endif
238
239 // Cpu architecture string
240 static char cpu_arch[] = HOTSPOT_LIB_ARCH;
241
242 // pid_t gettid()
243 //
244 // Returns the kernel thread id of the currently running thread. Kernel
245 // thread id is used to access /proc.
246 //
247 // (Note that getpid() on LinuxThreads returns kernel thread id too; but
248 // on NPTL, it returns the same pid for all threads, as required by POSIX.)
249 //
250 pid_t os::Linux::gettid() {
251 int rslt = syscall(SYS_gettid);
252 if (rslt == -1) {
253 // old kernel, no NPTL support
254 return getpid();
255 } else {
256 return (pid_t)rslt;
257 }
258 }
259
260 // Most versions of linux have a bug where the number of processors are
261 // determined by looking at the /proc file system. In a chroot environment,
262 // the system call returns 1. This causes the VM to act as if it is
263 // a single processor and elide locking (see is_MP() call).
264 static bool unsafe_chroot_detected = false;
265 static const char *unstable_chroot_error = "/proc file system not found.\n"
266 "Java may be unstable running multithreaded in a chroot "
267 "environment on Linux when /proc filesystem is not mounted.";
268
269 void os::Linux::initialize_system_info() {
270 set_processor_count(sysconf(_SC_NPROCESSORS_CONF));
271 if (processor_count() == 1) {
272 pid_t pid = os::Linux::gettid();
273 char fname[32];
274 jio_snprintf(fname, sizeof(fname), "/proc/%d", pid);
275 FILE *fp = fopen(fname, "r");
276 if (fp == NULL) {
277 unsafe_chroot_detected = true;
278 } else {
279 fclose(fp);
280 }
281 }
282 _physical_memory = (julong)sysconf(_SC_PHYS_PAGES) * (julong)sysconf(_SC_PAGESIZE);
283 assert(processor_count() > 0, "linux error");
284 }
285
286 void os::init_system_properties_values() {
287 // The next steps are taken in the product version:
288 //
289 // Obtain the JAVA_HOME value from the location of libjvm.so.
290 // This library should be located at:
291 // <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm.so.
292 //
293 // If "/jre/lib/" appears at the right place in the path, then we
294 // assume libjvm.so is installed in a JDK and we use this path.
295 //
296 // Otherwise exit with message: "Could not create the Java virtual machine."
297 //
298 // The following extra steps are taken in the debugging version:
299 //
300 // If "/jre/lib/" does NOT appear at the right place in the path
301 // instead of exit check for $JAVA_HOME environment variable.
302 //
303 // If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>,
304 // then we append a fake suffix "hotspot/libjvm.so" to this path so
305 // it looks like libjvm.so is installed there
306 // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm.so.
307 //
308 // Otherwise exit.
309 //
310 // Important note: if the location of libjvm.so changes this
311 // code needs to be changed accordingly.
312
313 // See ld(1):
314 // The linker uses the following search paths to locate required
315 // shared libraries:
316 // 1: ...
317 // ...
318 // 7: The default directories, normally /lib and /usr/lib.
319 #if defined(AMD64) || defined(_LP64) && (defined(SPARC) || defined(PPC) || defined(S390))
320 #define DEFAULT_LIBPATH "/usr/lib64:/lib64:/lib:/usr/lib"
321 #else
322 #define DEFAULT_LIBPATH "/lib:/usr/lib"
323 #endif
324
325 // Base path of extensions installed on the system.
326 #define SYS_EXT_DIR "/usr/java/packages"
327 #define EXTENSIONS_DIR "/lib/ext"
328 #define ENDORSED_DIR "/lib/endorsed"
329
330 // Buffer that fits several sprintfs.
331 // Note that the space for the colon and the trailing null are provided
332 // by the nulls included by the sizeof operator.
333 const size_t bufsize =
334 MAX3((size_t)MAXPATHLEN, // For dll_dir & friends.
335 (size_t)MAXPATHLEN + sizeof(EXTENSIONS_DIR) + sizeof(SYS_EXT_DIR) + sizeof(EXTENSIONS_DIR), // extensions dir
336 (size_t)MAXPATHLEN + sizeof(ENDORSED_DIR)); // endorsed dir
337 char *buf = (char *)NEW_C_HEAP_ARRAY(char, bufsize, mtInternal);
338
339 // sysclasspath, java_home, dll_dir
340 {
341 char *pslash;
342 os::jvm_path(buf, bufsize);
343
344 // Found the full path to libjvm.so.
345 // Now cut the path to <java_home>/jre if we can.
346 *(strrchr(buf, '/')) = '\0'; // Get rid of /libjvm.so.
347 pslash = strrchr(buf, '/');
348 if (pslash != NULL) {
349 *pslash = '\0'; // Get rid of /{client|server|hotspot}.
350 }
351 Arguments::set_dll_dir(buf);
352
353 if (pslash != NULL) {
354 pslash = strrchr(buf, '/');
355 if (pslash != NULL) {
356 *pslash = '\0'; // Get rid of /<arch>.
357 pslash = strrchr(buf, '/');
358 if (pslash != NULL) {
359 *pslash = '\0'; // Get rid of /lib.
360 }
361 }
362 }
363 Arguments::set_java_home(buf);
364 set_boot_path('/', ':');
365 }
366
367 // Where to look for native libraries.
368 //
369 // Note: Due to a legacy implementation, most of the library path
370 // is set in the launcher. This was to accomodate linking restrictions
371 // on legacy Linux implementations (which are no longer supported).
372 // Eventually, all the library path setting will be done here.
373 //
374 // However, to prevent the proliferation of improperly built native
375 // libraries, the new path component /usr/java/packages is added here.
376 // Eventually, all the library path setting will be done here.
377 {
378 // Get the user setting of LD_LIBRARY_PATH, and prepended it. It
379 // should always exist (until the legacy problem cited above is
380 // addressed).
381 const char *v = ::getenv("LD_LIBRARY_PATH");
382 const char *v_colon = ":";
383 if (v == NULL) { v = ""; v_colon = ""; }
384 // That's +1 for the colon and +1 for the trailing '\0'.
385 char *ld_library_path = (char *)NEW_C_HEAP_ARRAY(char,
386 strlen(v) + 1 +
387 sizeof(SYS_EXT_DIR) + sizeof("/lib/") + strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH) + 1,
388 mtInternal);
389 sprintf(ld_library_path, "%s%s" SYS_EXT_DIR "/lib/%s:" DEFAULT_LIBPATH, v, v_colon, cpu_arch);
390 Arguments::set_library_path(ld_library_path);
391 FREE_C_HEAP_ARRAY(char, ld_library_path, mtInternal);
392 }
393
394 // Extensions directories.
395 sprintf(buf, "%s" EXTENSIONS_DIR ":" SYS_EXT_DIR EXTENSIONS_DIR, Arguments::get_java_home());
396 Arguments::set_ext_dirs(buf);
397
398 // Endorsed standards default directory.
399 sprintf(buf, "%s" ENDORSED_DIR, Arguments::get_java_home());
400 Arguments::set_endorsed_dirs(buf);
401
402 FREE_C_HEAP_ARRAY(char, buf, mtInternal);
403
404 #undef DEFAULT_LIBPATH
405 #undef SYS_EXT_DIR
406 #undef EXTENSIONS_DIR
407 #undef ENDORSED_DIR
408 }
409
410 ////////////////////////////////////////////////////////////////////////////////
411 // breakpoint support
412
413 void os::breakpoint() {
414 BREAKPOINT;
415 }
416
417 extern "C" void breakpoint() {
418 // use debugger to set breakpoint here
419 }
420
421 ////////////////////////////////////////////////////////////////////////////////
422 // signal support
423
424 debug_only(static bool signal_sets_initialized = false);
425 static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs;
426
427 bool os::Linux::is_sig_ignored(int sig) {
428 struct sigaction oact;
429 sigaction(sig, (struct sigaction*)NULL, &oact);
430 void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*, oact.sa_sigaction)
431 : CAST_FROM_FN_PTR(void*, oact.sa_handler);
432 if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN))
433 return true;
434 else
435 return false;
436 }
437
438 void os::Linux::signal_sets_init() {
439 // Should also have an assertion stating we are still single-threaded.
440 assert(!signal_sets_initialized, "Already initialized");
441 // Fill in signals that are necessarily unblocked for all threads in
442 // the VM. Currently, we unblock the following signals:
443 // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden
444 // by -Xrs (=ReduceSignalUsage));
445 // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all
446 // other threads. The "ReduceSignalUsage" boolean tells us not to alter
447 // the dispositions or masks wrt these signals.
448 // Programs embedding the VM that want to use the above signals for their
449 // own purposes must, at this time, use the "-Xrs" option to prevent
450 // interference with shutdown hooks and BREAK_SIGNAL thread dumping.
451 // (See bug 4345157, and other related bugs).
452 // In reality, though, unblocking these signals is really a nop, since
453 // these signals are not blocked by default.
454 sigemptyset(&unblocked_sigs);
455 sigemptyset(&allowdebug_blocked_sigs);
456 sigaddset(&unblocked_sigs, SIGILL);
457 sigaddset(&unblocked_sigs, SIGSEGV);
458 sigaddset(&unblocked_sigs, SIGBUS);
459 sigaddset(&unblocked_sigs, SIGFPE);
460 #if defined(PPC64)
461 sigaddset(&unblocked_sigs, SIGTRAP);
462 #endif
463 sigaddset(&unblocked_sigs, SR_signum);
464
465 if (!ReduceSignalUsage) {
466 if (!os::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) {
467 sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL);
468 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL);
469 }
470 if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) {
471 sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL);
472 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL);
473 }
474 if (!os::Linux::is_sig_ignored(SHUTDOWN3_SIGNAL)) {
475 sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL);
476 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN3_SIGNAL);
477 }
478 }
479 // Fill in signals that are blocked by all but the VM thread.
480 sigemptyset(&vm_sigs);
481 if (!ReduceSignalUsage)
482 sigaddset(&vm_sigs, BREAK_SIGNAL);
483 debug_only(signal_sets_initialized = true);
484
485 }
486
487 // These are signals that are unblocked while a thread is running Java.
488 // (For some reason, they get blocked by default.)
489 sigset_t* os::Linux::unblocked_signals() {
490 assert(signal_sets_initialized, "Not initialized");
491 return &unblocked_sigs;
492 }
493
494 // These are the signals that are blocked while a (non-VM) thread is
495 // running Java. Only the VM thread handles these signals.
496 sigset_t* os::Linux::vm_signals() {
497 assert(signal_sets_initialized, "Not initialized");
498 return &vm_sigs;
499 }
500
501 // These are signals that are blocked during cond_wait to allow debugger in
502 sigset_t* os::Linux::allowdebug_blocked_signals() {
503 assert(signal_sets_initialized, "Not initialized");
504 return &allowdebug_blocked_sigs;
505 }
506
507 void os::Linux::hotspot_sigmask(Thread* thread) {
508
509 //Save caller's signal mask before setting VM signal mask
510 sigset_t caller_sigmask;
511 pthread_sigmask(SIG_BLOCK, NULL, &caller_sigmask);
512
513 OSThread* osthread = thread->osthread();
514 osthread->set_caller_sigmask(caller_sigmask);
515
516 pthread_sigmask(SIG_UNBLOCK, os::Linux::unblocked_signals(), NULL);
517
518 if (!ReduceSignalUsage) {
519 if (thread->is_VM_thread()) {
520 // Only the VM thread handles BREAK_SIGNAL ...
521 pthread_sigmask(SIG_UNBLOCK, vm_signals(), NULL);
522 } else {
523 // ... all other threads block BREAK_SIGNAL
524 pthread_sigmask(SIG_BLOCK, vm_signals(), NULL);
525 }
526 }
527 }
528
529 //////////////////////////////////////////////////////////////////////////////
530 // detecting pthread library
531
532 void os::Linux::libpthread_init() {
533 // Save glibc and pthread version strings. Note that _CS_GNU_LIBC_VERSION
534 // and _CS_GNU_LIBPTHREAD_VERSION are supported in glibc >= 2.3.2. Use a
535 // generic name for earlier versions.
536 // Define macros here so we can build HotSpot on old systems.
537 # ifndef _CS_GNU_LIBC_VERSION
538 # define _CS_GNU_LIBC_VERSION 2
539 # endif
540 # ifndef _CS_GNU_LIBPTHREAD_VERSION
541 # define _CS_GNU_LIBPTHREAD_VERSION 3
542 # endif
543
544 size_t n = confstr(_CS_GNU_LIBC_VERSION, NULL, 0);
545 if (n > 0) {
546 char *str = (char *)malloc(n, mtInternal);
547 confstr(_CS_GNU_LIBC_VERSION, str, n);
548 os::Linux::set_glibc_version(str);
549 } else {
550 // _CS_GNU_LIBC_VERSION is not supported, try gnu_get_libc_version()
551 static char _gnu_libc_version[32];
552 jio_snprintf(_gnu_libc_version, sizeof(_gnu_libc_version),
553 "glibc %s %s", gnu_get_libc_version(), gnu_get_libc_release());
554 os::Linux::set_glibc_version(_gnu_libc_version);
555 }
556
557 n = confstr(_CS_GNU_LIBPTHREAD_VERSION, NULL, 0);
558 if (n > 0) {
559 char *str = (char *)malloc(n, mtInternal);
560 confstr(_CS_GNU_LIBPTHREAD_VERSION, str, n);
561 // Vanilla RH-9 (glibc 2.3.2) has a bug that confstr() always tells
562 // us "NPTL-0.29" even we are running with LinuxThreads. Check if this
563 // is the case. LinuxThreads has a hard limit on max number of threads.
564 // So sysconf(_SC_THREAD_THREADS_MAX) will return a positive value.
565 // On the other hand, NPTL does not have such a limit, sysconf()
566 // will return -1 and errno is not changed. Check if it is really NPTL.
567 if (strcmp(os::Linux::glibc_version(), "glibc 2.3.2") == 0 &&
568 strstr(str, "NPTL") &&
569 sysconf(_SC_THREAD_THREADS_MAX) > 0) {
570 free(str);
571 os::Linux::set_libpthread_version("linuxthreads");
572 } else {
573 os::Linux::set_libpthread_version(str);
574 }
575 } else {
576 // glibc before 2.3.2 only has LinuxThreads.
577 os::Linux::set_libpthread_version("linuxthreads");
578 }
579
580 if (strstr(libpthread_version(), "NPTL")) {
581 os::Linux::set_is_NPTL();
582 } else {
583 os::Linux::set_is_LinuxThreads();
584 }
585
586 // LinuxThreads have two flavors: floating-stack mode, which allows variable
587 // stack size; and fixed-stack mode. NPTL is always floating-stack.
588 if (os::Linux::is_NPTL() || os::Linux::supports_variable_stack_size()) {
589 os::Linux::set_is_floating_stack();
590 }
591 }
592
593 /////////////////////////////////////////////////////////////////////////////
594 // thread stack
595
596 // Force Linux kernel to expand current thread stack. If "bottom" is close
597 // to the stack guard, caller should block all signals.
598 //
599 // MAP_GROWSDOWN:
600 // A special mmap() flag that is used to implement thread stacks. It tells
601 // kernel that the memory region should extend downwards when needed. This
602 // allows early versions of LinuxThreads to only mmap the first few pages
603 // when creating a new thread. Linux kernel will automatically expand thread
604 // stack as needed (on page faults).
605 //
606 // However, because the memory region of a MAP_GROWSDOWN stack can grow on
607 // demand, if a page fault happens outside an already mapped MAP_GROWSDOWN
608 // region, it's hard to tell if the fault is due to a legitimate stack
609 // access or because of reading/writing non-exist memory (e.g. buffer
610 // overrun). As a rule, if the fault happens below current stack pointer,
611 // Linux kernel does not expand stack, instead a SIGSEGV is sent to the
612 // application (see Linux kernel fault.c).
613 //
614 // This Linux feature can cause SIGSEGV when VM bangs thread stack for
615 // stack overflow detection.
616 //
617 // Newer version of LinuxThreads (since glibc-2.2, or, RH-7.x) and NPTL do
618 // not use this flag. However, the stack of initial thread is not created
619 // by pthread, it is still MAP_GROWSDOWN. Also it's possible (though
620 // unlikely) that user code can create a thread with MAP_GROWSDOWN stack
621 // and then attach the thread to JVM.
622 //
623 // To get around the problem and allow stack banging on Linux, we need to
624 // manually expand thread stack after receiving the SIGSEGV.
625 //
626 // There are two ways to expand thread stack to address "bottom", we used
627 // both of them in JVM before 1.5:
628 // 1. adjust stack pointer first so that it is below "bottom", and then
629 // touch "bottom"
630 // 2. mmap() the page in question
631 //
632 // Now alternate signal stack is gone, it's harder to use 2. For instance,
633 // if current sp is already near the lower end of page 101, and we need to
634 // call mmap() to map page 100, it is possible that part of the mmap() frame
635 // will be placed in page 100. When page 100 is mapped, it is zero-filled.
636 // That will destroy the mmap() frame and cause VM to crash.
637 //
638 // The following code works by adjusting sp first, then accessing the "bottom"
639 // page to force a page fault. Linux kernel will then automatically expand the
640 // stack mapping.
641 //
642 // _expand_stack_to() assumes its frame size is less than page size, which
643 // should always be true if the function is not inlined.
644
645 #if __GNUC__ < 3 // gcc 2.x does not support noinline attribute
646 #define NOINLINE
647 #else
648 #define NOINLINE __attribute__ ((noinline))
649 #endif
650
651 static void _expand_stack_to(address bottom) NOINLINE;
652
653 static void _expand_stack_to(address bottom) {
654 address sp;
655 size_t size;
656 volatile char *p;
657
658 // Adjust bottom to point to the largest address within the same page, it
659 // gives us a one-page buffer if alloca() allocates slightly more memory.
660 bottom = (address)align_size_down((uintptr_t)bottom, os::Linux::page_size());
661 bottom += os::Linux::page_size() - 1;
662
663 // sp might be slightly above current stack pointer; if that's the case, we
664 // will alloca() a little more space than necessary, which is OK. Don't use
665 // os::current_stack_pointer(), as its result can be slightly below current
666 // stack pointer, causing us to not alloca enough to reach "bottom".
667 sp = (address)&sp;
668
669 if (sp > bottom) {
670 size = sp - bottom;
671 p = (volatile char *)alloca(size);
672 assert(p != NULL && p <= (volatile char *)bottom, "alloca problem?");
673 p[0] = '\0';
674 }
675 }
676
677 bool os::Linux::manually_expand_stack(JavaThread * t, address addr) {
678 assert(t!=NULL, "just checking");
679 assert(t->osthread()->expanding_stack(), "expand should be set");
680 assert(t->stack_base() != NULL, "stack_base was not initialized");
681
682 if (addr < t->stack_base() && addr >= t->stack_yellow_zone_base()) {
683 sigset_t mask_all, old_sigset;
684 sigfillset(&mask_all);
685 pthread_sigmask(SIG_SETMASK, &mask_all, &old_sigset);
686 _expand_stack_to(addr);
687 pthread_sigmask(SIG_SETMASK, &old_sigset, NULL);
688 return true;
689 }
690 return false;
691 }
692
693 //////////////////////////////////////////////////////////////////////////////
694 // create new thread
695
696 static address highest_vm_reserved_address();
697
698 // check if it's safe to start a new thread
699 static bool _thread_safety_check(Thread* thread) {
700 if (os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack()) {
701 // Fixed stack LinuxThreads (SuSE Linux/x86, and some versions of Redhat)
702 // Heap is mmap'ed at lower end of memory space. Thread stacks are
703 // allocated (MAP_FIXED) from high address space. Every thread stack
704 // occupies a fixed size slot (usually 2Mbytes, but user can change
705 // it to other values if they rebuild LinuxThreads).
706 //
707 // Problem with MAP_FIXED is that mmap() can still succeed even part of
708 // the memory region has already been mmap'ed. That means if we have too
709 // many threads and/or very large heap, eventually thread stack will
710 // collide with heap.
711 //
712 // Here we try to prevent heap/stack collision by comparing current
713 // stack bottom with the highest address that has been mmap'ed by JVM
714 // plus a safety margin for memory maps created by native code.
715 //
716 // This feature can be disabled by setting ThreadSafetyMargin to 0
717 //
718 if (ThreadSafetyMargin > 0) {
719 address stack_bottom = os::current_stack_base() - os::current_stack_size();
720
721 // not safe if our stack extends below the safety margin
722 return stack_bottom - ThreadSafetyMargin >= highest_vm_reserved_address();
723 } else {
724 return true;
725 }
726 } else {
727 // Floating stack LinuxThreads or NPTL:
728 // Unlike fixed stack LinuxThreads, thread stacks are not MAP_FIXED. When
729 // there's not enough space left, pthread_create() will fail. If we come
730 // here, that means enough space has been reserved for stack.
731 return true;
732 }
733 }
734
735 // Thread start routine for all newly created threads
736 static void *java_start(Thread *thread) {
737 // Try to randomize the cache line index of hot stack frames.
738 // This helps when threads of the same stack traces evict each other's
739 // cache lines. The threads can be either from the same JVM instance, or
740 // from different JVM instances. The benefit is especially true for
741 // processors with hyperthreading technology.
742 static int counter = 0;
743 int pid = os::current_process_id();
744 alloca(((pid ^ counter++) & 7) * 128);
745
746 ThreadLocalStorage::set_thread(thread);
747
748 OSThread* osthread = thread->osthread();
749 Monitor* sync = osthread->startThread_lock();
750
751 // non floating stack LinuxThreads needs extra check, see above
752 if (!_thread_safety_check(thread)) {
753 // notify parent thread
754 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
755 osthread->set_state(ZOMBIE);
756 sync->notify_all();
757 return NULL;
758 }
759
760 // thread_id is kernel thread id (similar to Solaris LWP id)
761 osthread->set_thread_id(os::Linux::gettid());
762
763 if (UseNUMA) {
764 int lgrp_id = os::numa_get_group_id();
765 if (lgrp_id != -1) {
766 thread->set_lgrp_id(lgrp_id);
767 }
768 }
769 // initialize signal mask for this thread
770 os::Linux::hotspot_sigmask(thread);
771
772 // initialize floating point control register
773 os::Linux::init_thread_fpu_state();
774
775 // handshaking with parent thread
776 {
777 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
778
779 // notify parent thread
780 osthread->set_state(INITIALIZED);
781 sync->notify_all();
782
783 // wait until os::start_thread()
784 while (osthread->get_state() == INITIALIZED) {
785 sync->wait(Mutex::_no_safepoint_check_flag);
786 }
787 }
788
789 // call one more level start routine
790 thread->run();
791
792 return 0;
793 }
794
795 bool os::create_thread(Thread* thread, ThreadType thr_type, size_t stack_size) {
796 assert(thread->osthread() == NULL, "caller responsible");
797
798 // Allocate the OSThread object
799 OSThread* osthread = new OSThread(NULL, NULL);
800 if (osthread == NULL) {
801 return false;
802 }
803
804 // set the correct thread state
805 osthread->set_thread_type(thr_type);
806
807 // Initial state is ALLOCATED but not INITIALIZED
808 osthread->set_state(ALLOCATED);
809
810 thread->set_osthread(osthread);
811
812 // init thread attributes
813 pthread_attr_t attr;
814 pthread_attr_init(&attr);
815 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
816
817 // stack size
818 if (os::Linux::supports_variable_stack_size()) {
819 // calculate stack size if it's not specified by caller
820 if (stack_size == 0) {
821 stack_size = os::Linux::default_stack_size(thr_type);
822
823 switch (thr_type) {
824 case os::java_thread:
825 // Java threads use ThreadStackSize which default value can be
826 // changed with the flag -Xss
827 assert (JavaThread::stack_size_at_create() > 0, "this should be set");
828 stack_size = JavaThread::stack_size_at_create();
829 break;
830 case os::compiler_thread:
831 if (CompilerThreadStackSize > 0) {
832 stack_size = (size_t)(CompilerThreadStackSize * K);
833 break;
834 } // else fall through:
835 // use VMThreadStackSize if CompilerThreadStackSize is not defined
836 case os::vm_thread:
837 case os::pgc_thread:
838 case os::cgc_thread:
839 case os::watcher_thread:
840 if (VMThreadStackSize > 0) stack_size = (size_t)(VMThreadStackSize * K);
841 break;
842 }
843 }
844
845 stack_size = MAX2(stack_size, os::Linux::min_stack_allowed);
846 pthread_attr_setstacksize(&attr, stack_size);
847 } else {
848 // let pthread_create() pick the default value.
849 }
850
851 // glibc guard page
852 pthread_attr_setguardsize(&attr, os::Linux::default_guard_size(thr_type));
853
854 ThreadState state;
855
856 {
857 // Serialize thread creation if we are running with fixed stack LinuxThreads
858 bool lock = os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack();
859 if (lock) {
860 os::Linux::createThread_lock()->lock_without_safepoint_check();
861 }
862
863 pthread_t tid;
864 int ret = pthread_create(&tid, &attr, (void* (*)(void*)) java_start, thread);
865
866 pthread_attr_destroy(&attr);
867
868 if (ret != 0) {
869 if (PrintMiscellaneous && (Verbose || WizardMode)) {
870 perror("pthread_create()");
871 }
872 // Need to clean up stuff we've allocated so far
873 thread->set_osthread(NULL);
874 delete osthread;
875 if (lock) os::Linux::createThread_lock()->unlock();
876 return false;
877 }
878
879 // Store pthread info into the OSThread
880 osthread->set_pthread_id(tid);
881
882 // Wait until child thread is either initialized or aborted
883 {
884 Monitor* sync_with_child = osthread->startThread_lock();
885 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
886 while ((state = osthread->get_state()) == ALLOCATED) {
887 sync_with_child->wait(Mutex::_no_safepoint_check_flag);
888 }
889 }
890
891 if (lock) {
892 os::Linux::createThread_lock()->unlock();
893 }
894 }
895
896 // Aborted due to thread limit being reached
897 if (state == ZOMBIE) {
898 thread->set_osthread(NULL);
899 delete osthread;
900 return false;
901 }
902
903 // The thread is returned suspended (in state INITIALIZED),
904 // and is started higher up in the call chain
905 assert(state == INITIALIZED, "race condition");
906 return true;
907 }
908
909 /////////////////////////////////////////////////////////////////////////////
910 // attach existing thread
911
912 // bootstrap the main thread
913 bool os::create_main_thread(JavaThread* thread) {
914 assert(os::Linux::_main_thread == pthread_self(), "should be called inside main thread");
915 return create_attached_thread(thread);
916 }
917
918 bool os::create_attached_thread(JavaThread* thread) {
919 #ifdef ASSERT
920 thread->verify_not_published();
921 #endif
922
923 // Allocate the OSThread object
924 OSThread* osthread = new OSThread(NULL, NULL);
925
926 if (osthread == NULL) {
927 return false;
928 }
929
930 // Store pthread info into the OSThread
931 osthread->set_thread_id(os::Linux::gettid());
932 osthread->set_pthread_id(::pthread_self());
933
934 // initialize floating point control register
935 os::Linux::init_thread_fpu_state();
936
937 // Initial thread state is RUNNABLE
938 osthread->set_state(RUNNABLE);
939
940 thread->set_osthread(osthread);
941
942 if (UseNUMA) {
943 int lgrp_id = os::numa_get_group_id();
944 if (lgrp_id != -1) {
945 thread->set_lgrp_id(lgrp_id);
946 }
947 }
948
949 if (os::Linux::is_initial_thread()) {
950 // If current thread is initial thread, its stack is mapped on demand,
951 // see notes about MAP_GROWSDOWN. Here we try to force kernel to map
952 // the entire stack region to avoid SEGV in stack banging.
953 // It is also useful to get around the heap-stack-gap problem on SuSE
954 // kernel (see 4821821 for details). We first expand stack to the top
955 // of yellow zone, then enable stack yellow zone (order is significant,
956 // enabling yellow zone first will crash JVM on SuSE Linux), so there
957 // is no gap between the last two virtual memory regions.
958
959 JavaThread *jt = (JavaThread *)thread;
960 address addr = jt->stack_yellow_zone_base();
961 assert(addr != NULL, "initialization problem?");
962 assert(jt->stack_available(addr) > 0, "stack guard should not be enabled");
963
964 osthread->set_expanding_stack();
965 os::Linux::manually_expand_stack(jt, addr);
966 osthread->clear_expanding_stack();
967 }
968
969 // initialize signal mask for this thread
970 // and save the caller's signal mask
971 os::Linux::hotspot_sigmask(thread);
972
973 return true;
974 }
975
976 void os::pd_start_thread(Thread* thread) {
977 OSThread * osthread = thread->osthread();
978 assert(osthread->get_state() != INITIALIZED, "just checking");
979 Monitor* sync_with_child = osthread->startThread_lock();
980 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
981 sync_with_child->notify();
982 }
983
984 // Free Linux resources related to the OSThread
985 void os::free_thread(OSThread* osthread) {
986 assert(osthread != NULL, "osthread not set");
987
988 if (Thread::current()->osthread() == osthread) {
989 // Restore caller's signal mask
990 sigset_t sigmask = osthread->caller_sigmask();
991 pthread_sigmask(SIG_SETMASK, &sigmask, NULL);
992 }
993
994 delete osthread;
995 }
996
997 //////////////////////////////////////////////////////////////////////////////
998 // thread local storage
999
1000 // Restore the thread pointer if the destructor is called. This is in case
1001 // someone from JNI code sets up a destructor with pthread_key_create to run
1002 // detachCurrentThread on thread death. Unless we restore the thread pointer we
1003 // will hang or crash. When detachCurrentThread is called the key will be set
1004 // to null and we will not be called again. If detachCurrentThread is never
1005 // called we could loop forever depending on the pthread implementation.
1006 static void restore_thread_pointer(void* p) {
1007 Thread* thread = (Thread*) p;
1008 os::thread_local_storage_at_put(ThreadLocalStorage::thread_index(), thread);
1009 }
1010
1011 int os::allocate_thread_local_storage() {
1012 pthread_key_t key;
1013 int rslt = pthread_key_create(&key, restore_thread_pointer);
1014 assert(rslt == 0, "cannot allocate thread local storage");
1015 return (int)key;
1016 }
1017
1018 // Note: This is currently not used by VM, as we don't destroy TLS key
1019 // on VM exit.
1020 void os::free_thread_local_storage(int index) {
1021 int rslt = pthread_key_delete((pthread_key_t)index);
1022 assert(rslt == 0, "invalid index");
1023 }
1024
1025 void os::thread_local_storage_at_put(int index, void* value) {
1026 int rslt = pthread_setspecific((pthread_key_t)index, value);
1027 assert(rslt == 0, "pthread_setspecific failed");
1028 }
1029
1030 extern "C" Thread* get_thread() {
1031 return ThreadLocalStorage::thread();
1032 }
1033
1034 //////////////////////////////////////////////////////////////////////////////
1035 // initial thread
1036
1037 // Check if current thread is the initial thread, similar to Solaris thr_main.
1038 bool os::Linux::is_initial_thread(void) {
1039 char dummy;
1040 // If called before init complete, thread stack bottom will be null.
1041 // Can be called if fatal error occurs before initialization.
1042 if (initial_thread_stack_bottom() == NULL) return false;
1043 assert(initial_thread_stack_bottom() != NULL &&
1044 initial_thread_stack_size() != 0,
1045 "os::init did not locate initial thread's stack region");
1046 if ((address)&dummy >= initial_thread_stack_bottom() &&
1047 (address)&dummy < initial_thread_stack_bottom() + initial_thread_stack_size())
1048 return true;
1049 else return false;
1050 }
1051
1052 // Find the virtual memory area that contains addr
1053 static bool find_vma(address addr, address* vma_low, address* vma_high) {
1054 FILE *fp = fopen("/proc/self/maps", "r");
1055 if (fp) {
1056 address low, high;
1057 while (!feof(fp)) {
1058 if (fscanf(fp, "%p-%p", &low, &high) == 2) {
1059 if (low <= addr && addr < high) {
1060 if (vma_low) *vma_low = low;
1061 if (vma_high) *vma_high = high;
1062 fclose (fp);
1063 return true;
1064 }
1065 }
1066 for (;;) {
1067 int ch = fgetc(fp);
1068 if (ch == EOF || ch == (int)'\n') break;
1069 }
1070 }
1071 fclose(fp);
1072 }
1073 return false;
1074 }
1075
1076 // Locate initial thread stack. This special handling of initial thread stack
1077 // is needed because pthread_getattr_np() on most (all?) Linux distros returns
1078 // bogus value for the primordial process thread. While the launcher has created
1079 // the VM in a new thread since JDK 6, we still have to allow for the use of the
1080 // JNI invocation API from a primordial thread.
1081 void os::Linux::capture_initial_stack(size_t max_size) {
1082
1083 // max_size is either 0 (which means accept OS default for thread stacks) or
1084 // a user-specified value known to be at least the minimum needed. If we
1085 // are actually on the primordial thread we can make it appear that we have a
1086 // smaller max_size stack by inserting the guard pages at that location. But we
1087 // cannot do anything to emulate a larger stack than what has been provided by
1088 // the OS or threading library. In fact if we try to use a stack greater than
1089 // what is set by rlimit then we will crash the hosting process.
1090
1091 // Maximum stack size is the easy part, get it from RLIMIT_STACK.
1092 // If this is "unlimited" then it will be a huge value.
1093 struct rlimit rlim;
1094 getrlimit(RLIMIT_STACK, &rlim);
1095 size_t stack_size = rlim.rlim_cur;
1096
1097 // 6308388: a bug in ld.so will relocate its own .data section to the
1098 // lower end of primordial stack; reduce ulimit -s value a little bit
1099 // so we won't install guard page on ld.so's data section.
1100 stack_size -= 2 * page_size();
1101
1102 // Try to figure out where the stack base (top) is. This is harder.
1103 //
1104 // When an application is started, glibc saves the initial stack pointer in
1105 // a global variable "__libc_stack_end", which is then used by system
1106 // libraries. __libc_stack_end should be pretty close to stack top. The
1107 // variable is available since the very early days. However, because it is
1108 // a private interface, it could disappear in the future.
1109 //
1110 // Linux kernel saves start_stack information in /proc/<pid>/stat. Similar
1111 // to __libc_stack_end, it is very close to stack top, but isn't the real
1112 // stack top. Note that /proc may not exist if VM is running as a chroot
1113 // program, so reading /proc/<pid>/stat could fail. Also the contents of
1114 // /proc/<pid>/stat could change in the future (though unlikely).
1115 //
1116 // We try __libc_stack_end first. If that doesn't work, look for
1117 // /proc/<pid>/stat. If neither of them works, we use current stack pointer
1118 // as a hint, which should work well in most cases.
1119
1120 uintptr_t stack_start;
1121
1122 // try __libc_stack_end first
1123 uintptr_t *p = (uintptr_t *)dlsym(RTLD_DEFAULT, "__libc_stack_end");
1124 if (p && *p) {
1125 stack_start = *p;
1126 } else {
1127 // see if we can get the start_stack field from /proc/self/stat
1128 FILE *fp;
1129 int pid;
1130 char state;
1131 int ppid;
1132 int pgrp;
1133 int session;
1134 int nr;
1135 int tpgrp;
1136 unsigned long flags;
1137 unsigned long minflt;
1138 unsigned long cminflt;
1139 unsigned long majflt;
1140 unsigned long cmajflt;
1141 unsigned long utime;
1142 unsigned long stime;
1143 long cutime;
1144 long cstime;
1145 long prio;
1146 long nice;
1147 long junk;
1148 long it_real;
1149 uintptr_t start;
1150 uintptr_t vsize;
1151 intptr_t rss;
1152 uintptr_t rsslim;
1153 uintptr_t scodes;
1154 uintptr_t ecode;
1155 int i;
1156
1157 // Figure what the primordial thread stack base is. Code is inspired
1158 // by email from Hans Boehm. /proc/self/stat begins with current pid,
1159 // followed by command name surrounded by parentheses, state, etc.
1160 char stat[2048];
1161 int statlen;
1162
1163 fp = fopen("/proc/self/stat", "r");
1164 if (fp) {
1165 statlen = fread(stat, 1, 2047, fp);
1166 stat[statlen] = '\0';
1167 fclose(fp);
1168
1169 // Skip pid and the command string. Note that we could be dealing with
1170 // weird command names, e.g. user could decide to rename java launcher
1171 // to "java 1.4.2 :)", then the stat file would look like
1172 // 1234 (java 1.4.2 :)) R ... ...
1173 // We don't really need to know the command string, just find the last
1174 // occurrence of ")" and then start parsing from there. See bug 4726580.
1175 char * s = strrchr(stat, ')');
1176
1177 i = 0;
1178 if (s) {
1179 // Skip blank chars
1180 do s++; while (isspace(*s));
1181
1182 #define _UFM UINTX_FORMAT
1183 #define _DFM INTX_FORMAT
1184
1185 /* 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 */
1186 /* 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 */
1187 i = sscanf(s, "%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu %ld %ld %ld %ld %ld %ld " _UFM _UFM _DFM _UFM _UFM _UFM _UFM,
1188 &state, /* 3 %c */
1189 &ppid, /* 4 %d */
1190 &pgrp, /* 5 %d */
1191 &session, /* 6 %d */
1192 &nr, /* 7 %d */
1193 &tpgrp, /* 8 %d */
1194 &flags, /* 9 %lu */
1195 &minflt, /* 10 %lu */
1196 &cminflt, /* 11 %lu */
1197 &majflt, /* 12 %lu */
1198 &cmajflt, /* 13 %lu */
1199 &utime, /* 14 %lu */
1200 &stime, /* 15 %lu */
1201 &cutime, /* 16 %ld */
1202 &cstime, /* 17 %ld */
1203 &prio, /* 18 %ld */
1204 &nice, /* 19 %ld */
1205 &junk, /* 20 %ld */
1206 &it_real, /* 21 %ld */
1207 &start, /* 22 UINTX_FORMAT */
1208 &vsize, /* 23 UINTX_FORMAT */
1209 &rss, /* 24 INTX_FORMAT */
1210 &rsslim, /* 25 UINTX_FORMAT */
1211 &scodes, /* 26 UINTX_FORMAT */
1212 &ecode, /* 27 UINTX_FORMAT */
1213 &stack_start); /* 28 UINTX_FORMAT */
1214 }
1215
1216 #undef _UFM
1217 #undef _DFM
1218
1219 if (i != 28 - 2) {
1220 assert(false, "Bad conversion from /proc/self/stat");
1221 // product mode - assume we are the initial thread, good luck in the
1222 // embedded case.
1223 warning("Can't detect initial thread stack location - bad conversion");
1224 stack_start = (uintptr_t) &rlim;
1225 }
1226 } else {
1227 // For some reason we can't open /proc/self/stat (for example, running on
1228 // FreeBSD with a Linux emulator, or inside chroot), this should work for
1229 // most cases, so don't abort:
1230 warning("Can't detect initial thread stack location - no /proc/self/stat");
1231 stack_start = (uintptr_t) &rlim;
1232 }
1233 }
1234
1235 // Now we have a pointer (stack_start) very close to the stack top, the
1236 // next thing to do is to figure out the exact location of stack top. We
1237 // can find out the virtual memory area that contains stack_start by
1238 // reading /proc/self/maps, it should be the last vma in /proc/self/maps,
1239 // and its upper limit is the real stack top. (again, this would fail if
1240 // running inside chroot, because /proc may not exist.)
1241
1242 uintptr_t stack_top;
1243 address low, high;
1244 if (find_vma((address)stack_start, &low, &high)) {
1245 // success, "high" is the true stack top. (ignore "low", because initial
1246 // thread stack grows on demand, its real bottom is high - RLIMIT_STACK.)
1247 stack_top = (uintptr_t)high;
1248 } else {
1249 // failed, likely because /proc/self/maps does not exist
1250 warning("Can't detect initial thread stack location - find_vma failed");
1251 // best effort: stack_start is normally within a few pages below the real
1252 // stack top, use it as stack top, and reduce stack size so we won't put
1253 // guard page outside stack.
1254 stack_top = stack_start;
1255 stack_size -= 16 * page_size();
1256 }
1257
1258 // stack_top could be partially down the page so align it
1259 stack_top = align_size_up(stack_top, page_size());
1260
1261 // Allowed stack value is minimum of max_size and what we derived from rlimit
1262 if (max_size > 0) {
1263 _initial_thread_stack_size = MIN2(max_size, stack_size);
1264 } else {
1265 // Accept the rlimit max, but if stack is unlimited then it will be huge, so
1266 // clamp it at 8MB as we do on Solaris
1267 _initial_thread_stack_size = MIN2(stack_size, 8*M);
1268 }
1269
1270 _initial_thread_stack_size = align_size_down(_initial_thread_stack_size, page_size());
1271 _initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size;
1272 assert(_initial_thread_stack_bottom < (address)stack_top, "overflow!");
1273 }
1274
1275 ////////////////////////////////////////////////////////////////////////////////
1276 // time support
1277
1278 // Time since start-up in seconds to a fine granularity.
1279 // Used by VMSelfDestructTimer and the MemProfiler.
1280 double os::elapsedTime() {
1281
1282 return ((double)os::elapsed_counter()) / os::elapsed_frequency(); // nanosecond resolution
1283 }
1284
1285 jlong os::elapsed_counter() {
1286 return javaTimeNanos() - initial_time_count;
1287 }
1288
1289 jlong os::elapsed_frequency() {
1290 return NANOSECS_PER_SEC; // nanosecond resolution
1291 }
1292
1293 bool os::supports_vtime() { return true; }
1294 bool os::enable_vtime() { return false; }
1295 bool os::vtime_enabled() { return false; }
1296
1297 double os::elapsedVTime() {
1298 struct rusage usage;
1299 int retval = getrusage(RUSAGE_THREAD, &usage);
1300 if (retval == 0) {
1301 return (double) (usage.ru_utime.tv_sec + usage.ru_stime.tv_sec) + (double) (usage.ru_utime.tv_usec + usage.ru_stime.tv_usec) / (1000 * 1000);
1302 } else {
1303 // better than nothing, but not much
1304 return elapsedTime();
1305 }
1306 }
1307
1308 jlong os::javaTimeMillis() {
1309 timeval time;
1310 int status = gettimeofday(&time, NULL);
1311 assert(status != -1, "linux error");
1312 return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000);
1313 }
1314
1315 #ifndef CLOCK_MONOTONIC
1316 #define CLOCK_MONOTONIC (1)
1317 #endif
1318
1319 void os::Linux::clock_init() {
1320 // we do dlopen's in this particular order due to bug in linux
1321 // dynamical loader (see 6348968) leading to crash on exit
1322 void* handle = dlopen("librt.so.1", RTLD_LAZY);
1323 if (handle == NULL) {
1324 handle = dlopen("librt.so", RTLD_LAZY);
1325 }
1326
1327 if (handle) {
1328 int (*clock_getres_func)(clockid_t, struct timespec*) =
1329 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres");
1330 int (*clock_gettime_func)(clockid_t, struct timespec*) =
1331 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime");
1332 if (clock_getres_func && clock_gettime_func) {
1333 // See if monotonic clock is supported by the kernel. Note that some
1334 // early implementations simply return kernel jiffies (updated every
1335 // 1/100 or 1/1000 second). It would be bad to use such a low res clock
1336 // for nano time (though the monotonic property is still nice to have).
1337 // It's fixed in newer kernels, however clock_getres() still returns
1338 // 1/HZ. We check if clock_getres() works, but will ignore its reported
1339 // resolution for now. Hopefully as people move to new kernels, this
1340 // won't be a problem.
1341 struct timespec res;
1342 struct timespec tp;
1343 if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 &&
1344 clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) {
1345 // yes, monotonic clock is supported
1346 _clock_gettime = clock_gettime_func;
1347 return;
1348 } else {
1349 // close librt if there is no monotonic clock
1350 dlclose(handle);
1351 }
1352 }
1353 }
1354 warning("No monotonic clock was available - timed services may " \
1355 "be adversely affected if the time-of-day clock changes");
1356 }
1357
1358 #ifndef SYS_clock_getres
1359
1360 #if defined(IA32) || defined(AMD64)
1361 #define SYS_clock_getres IA32_ONLY(266) AMD64_ONLY(229)
1362 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y)
1363 #else
1364 #warning "SYS_clock_getres not defined for this platform, disabling fast_thread_cpu_time"
1365 #define sys_clock_getres(x,y) -1
1366 #endif
1367
1368 #else
1369 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y)
1370 #endif
1371
1372 void os::Linux::fast_thread_clock_init() {
1373 if (!UseLinuxPosixThreadCPUClocks) {
1374 return;
1375 }
1376 clockid_t clockid;
1377 struct timespec tp;
1378 int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) =
1379 (int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid");
1380
1381 // Switch to using fast clocks for thread cpu time if
1382 // the sys_clock_getres() returns 0 error code.
1383 // Note, that some kernels may support the current thread
1384 // clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks
1385 // returned by the pthread_getcpuclockid().
1386 // If the fast Posix clocks are supported then the sys_clock_getres()
1387 // must return at least tp.tv_sec == 0 which means a resolution
1388 // better than 1 sec. This is extra check for reliability.
1389
1390 if(pthread_getcpuclockid_func &&
1391 pthread_getcpuclockid_func(_main_thread, &clockid) == 0 &&
1392 sys_clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) {
1393
1394 _supports_fast_thread_cpu_time = true;
1395 _pthread_getcpuclockid = pthread_getcpuclockid_func;
1396 }
1397 }
1398
1399 jlong os::javaTimeNanos() {
1400 if (Linux::supports_monotonic_clock()) {
1401 struct timespec tp;
1402 int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp);
1403 assert(status == 0, "gettime error");
1404 jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec);
1405 return result;
1406 } else {
1407 timeval time;
1408 int status = gettimeofday(&time, NULL);
1409 assert(status != -1, "linux error");
1410 jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec);
1411 return 1000 * usecs;
1412 }
1413 }
1414
1415 void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) {
1416 if (Linux::supports_monotonic_clock()) {
1417 info_ptr->max_value = ALL_64_BITS;
1418
1419 // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past
1420 info_ptr->may_skip_backward = false; // not subject to resetting or drifting
1421 info_ptr->may_skip_forward = false; // not subject to resetting or drifting
1422 } else {
1423 // gettimeofday - based on time in seconds since the Epoch thus does not wrap
1424 info_ptr->max_value = ALL_64_BITS;
1425
1426 // gettimeofday is a real time clock so it skips
1427 info_ptr->may_skip_backward = true;
1428 info_ptr->may_skip_forward = true;
1429 }
1430
1431 info_ptr->kind = JVMTI_TIMER_ELAPSED; // elapsed not CPU time
1432 }
1433
1434 // Return the real, user, and system times in seconds from an
1435 // arbitrary fixed point in the past.
1436 bool os::getTimesSecs(double* process_real_time,
1437 double* process_user_time,
1438 double* process_system_time) {
1439 struct tms ticks;
1440 clock_t real_ticks = times(&ticks);
1441
1442 if (real_ticks == (clock_t) (-1)) {
1443 return false;
1444 } else {
1445 double ticks_per_second = (double) clock_tics_per_sec;
1446 *process_user_time = ((double) ticks.tms_utime) / ticks_per_second;
1447 *process_system_time = ((double) ticks.tms_stime) / ticks_per_second;
1448 *process_real_time = ((double) real_ticks) / ticks_per_second;
1449
1450 return true;
1451 }
1452 }
1453
1454
1455 char * os::local_time_string(char *buf, size_t buflen) {
1456 struct tm t;
1457 time_t long_time;
1458 time(&long_time);
1459 localtime_r(&long_time, &t);
1460 jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d",
1461 t.tm_year + 1900, t.tm_mon + 1, t.tm_mday,
1462 t.tm_hour, t.tm_min, t.tm_sec);
1463 return buf;
1464 }
1465
1466 struct tm* os::localtime_pd(const time_t* clock, struct tm* res) {
1467 return localtime_r(clock, res);
1468 }
1469
1470 ////////////////////////////////////////////////////////////////////////////////
1471 // runtime exit support
1472
1473 // Note: os::shutdown() might be called very early during initialization, or
1474 // called from signal handler. Before adding something to os::shutdown(), make
1475 // sure it is async-safe and can handle partially initialized VM.
1476 void os::shutdown() {
1477
1478 // allow PerfMemory to attempt cleanup of any persistent resources
1479 perfMemory_exit();
1480
1481 // needs to remove object in file system
1482 AttachListener::abort();
1483
1484 // flush buffered output, finish log files
1485 ostream_abort();
1486
1487 // Check for abort hook
1488 abort_hook_t abort_hook = Arguments::abort_hook();
1489 if (abort_hook != NULL) {
1490 abort_hook();
1491 }
1492
1493 }
1494
1495 // Note: os::abort() might be called very early during initialization, or
1496 // called from signal handler. Before adding something to os::abort(), make
1497 // sure it is async-safe and can handle partially initialized VM.
1498 void os::abort(bool dump_core) {
1499 os::shutdown();
1500 if (dump_core) {
1501 #ifndef PRODUCT
1502 fdStream out(defaultStream::output_fd());
1503 out.print_raw("Current thread is ");
1504 char buf[16];
1505 jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id());
1506 out.print_raw_cr(buf);
1507 out.print_raw_cr("Dumping core ...");
1508 #endif
1509 ::abort(); // dump core
1510 }
1511
1512 ::exit(1);
1513 }
1514
1515 // Die immediately, no exit hook, no abort hook, no cleanup.
1516 void os::die() {
1517 // _exit() on LinuxThreads only kills current thread
1518 ::abort();
1519 }
1520
1521
1522 // This method is a copy of JDK's sysGetLastErrorString
1523 // from src/solaris/hpi/src/system_md.c
1524
1525 size_t os::lasterror(char *buf, size_t len) {
1526
1527 if (errno == 0) return 0;
1528
1529 const char *s = ::strerror(errno);
1530 size_t n = ::strlen(s);
1531 if (n >= len) {
1532 n = len - 1;
1533 }
1534 ::strncpy(buf, s, n);
1535 buf[n] = '\0';
1536 return n;
1537 }
1538
1539 intx os::current_thread_id() { return (intx)pthread_self(); }
1540 int os::current_process_id() {
1541
1542 // Under the old linux thread library, linux gives each thread
1543 // its own process id. Because of this each thread will return
1544 // a different pid if this method were to return the result
1545 // of getpid(2). Linux provides no api that returns the pid
1546 // of the launcher thread for the vm. This implementation
1547 // returns a unique pid, the pid of the launcher thread
1548 // that starts the vm 'process'.
1549
1550 // Under the NPTL, getpid() returns the same pid as the
1551 // launcher thread rather than a unique pid per thread.
1552 // Use gettid() if you want the old pre NPTL behaviour.
1553
1554 // if you are looking for the result of a call to getpid() that
1555 // returns a unique pid for the calling thread, then look at the
1556 // OSThread::thread_id() method in osThread_linux.hpp file
1557
1558 return (int)(_initial_pid ? _initial_pid : getpid());
1559 }
1560
1561 // DLL functions
1562
1563 const char* os::dll_file_extension() { return ".so"; }
1564
1565 // This must be hard coded because it's the system's temporary
1566 // directory not the java application's temp directory, ala java.io.tmpdir.
1567 const char* os::get_temp_directory() { return "/tmp"; }
1568
1569 static bool file_exists(const char* filename) {
1570 struct stat statbuf;
1571 if (filename == NULL || strlen(filename) == 0) {
1572 return false;
1573 }
1574 return os::stat(filename, &statbuf) == 0;
1575 }
1576
1577 bool os::dll_build_name(char* buffer, size_t buflen,
1578 const char* pname, const char* fname) {
1579 bool retval = false;
1580 // Copied from libhpi
1581 const size_t pnamelen = pname ? strlen(pname) : 0;
1582
1583 // Return error on buffer overflow.
1584 if (pnamelen + strlen(fname) + 10 > (size_t) buflen) {
1585 return retval;
1586 }
1587
1588 if (pnamelen == 0) {
1589 snprintf(buffer, buflen, "lib%s.so", fname);
1590 retval = true;
1591 } else if (strchr(pname, *os::path_separator()) != NULL) {
1592 int n;
1593 char** pelements = split_path(pname, &n);
1594 if (pelements == NULL) {
1595 return false;
1596 }
1597 for (int i = 0 ; i < n ; i++) {
1598 // Really shouldn't be NULL, but check can't hurt
1599 if (pelements[i] == NULL || strlen(pelements[i]) == 0) {
1600 continue; // skip the empty path values
1601 }
1602 snprintf(buffer, buflen, "%s/lib%s.so", pelements[i], fname);
1603 if (file_exists(buffer)) {
1604 retval = true;
1605 break;
1606 }
1607 }
1608 // release the storage
1609 for (int i = 0 ; i < n ; i++) {
1610 if (pelements[i] != NULL) {
1611 FREE_C_HEAP_ARRAY(char, pelements[i], mtInternal);
1612 }
1613 }
1614 if (pelements != NULL) {
1615 FREE_C_HEAP_ARRAY(char*, pelements, mtInternal);
1616 }
1617 } else {
1618 snprintf(buffer, buflen, "%s/lib%s.so", pname, fname);
1619 retval = true;
1620 }
1621 return retval;
1622 }
1623
1624 // check if addr is inside libjvm.so
1625 bool os::address_is_in_vm(address addr) {
1626 static address libjvm_base_addr;
1627 Dl_info dlinfo;
1628
1629 if (libjvm_base_addr == NULL) {
1630 if (dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo) != 0) {
1631 libjvm_base_addr = (address)dlinfo.dli_fbase;
1632 }
1633 assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm");
1634 }
1635
1636 if (dladdr((void *)addr, &dlinfo) != 0) {
1637 if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true;
1638 }
1639
1640 return false;
1641 }
1642
1643 bool os::dll_address_to_function_name(address addr, char *buf,
1644 int buflen, int *offset) {
1645 // buf is not optional, but offset is optional
1646 assert(buf != NULL, "sanity check");
1647
1648 Dl_info dlinfo;
1649
1650 if (dladdr((void*)addr, &dlinfo) != 0) {
1651 // see if we have a matching symbol
1652 if (dlinfo.dli_saddr != NULL && dlinfo.dli_sname != NULL) {
1653 if (!Decoder::demangle(dlinfo.dli_sname, buf, buflen)) {
1654 jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname);
1655 }
1656 if (offset != NULL) *offset = addr - (address)dlinfo.dli_saddr;
1657 return true;
1658 }
1659 // no matching symbol so try for just file info
1660 if (dlinfo.dli_fname != NULL && dlinfo.dli_fbase != NULL) {
1661 if (Decoder::decode((address)(addr - (address)dlinfo.dli_fbase),
1662 buf, buflen, offset, dlinfo.dli_fname)) {
1663 return true;
1664 }
1665 }
1666 }
1667
1668 buf[0] = '\0';
1669 if (offset != NULL) *offset = -1;
1670 return false;
1671 }
1672
1673 struct _address_to_library_name {
1674 address addr; // input : memory address
1675 size_t buflen; // size of fname
1676 char* fname; // output: library name
1677 address base; // library base addr
1678 };
1679
1680 static int address_to_library_name_callback(struct dl_phdr_info *info,
1681 size_t size, void *data) {
1682 int i;
1683 bool found = false;
1684 address libbase = NULL;
1685 struct _address_to_library_name * d = (struct _address_to_library_name *)data;
1686
1687 // iterate through all loadable segments
1688 for (i = 0; i < info->dlpi_phnum; i++) {
1689 address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr);
1690 if (info->dlpi_phdr[i].p_type == PT_LOAD) {
1691 // base address of a library is the lowest address of its loaded
1692 // segments.
1693 if (libbase == NULL || libbase > segbase) {
1694 libbase = segbase;
1695 }
1696 // see if 'addr' is within current segment
1697 if (segbase <= d->addr &&
1698 d->addr < segbase + info->dlpi_phdr[i].p_memsz) {
1699 found = true;
1700 }
1701 }
1702 }
1703
1704 // dlpi_name is NULL or empty if the ELF file is executable, return 0
1705 // so dll_address_to_library_name() can fall through to use dladdr() which
1706 // can figure out executable name from argv[0].
1707 if (found && info->dlpi_name && info->dlpi_name[0]) {
1708 d->base = libbase;
1709 if (d->fname) {
1710 jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name);
1711 }
1712 return 1;
1713 }
1714 return 0;
1715 }
1716
1717 bool os::dll_address_to_library_name(address addr, char* buf,
1718 int buflen, int* offset) {
1719 // buf is not optional, but offset is optional
1720 assert(buf != NULL, "sanity check");
1721
1722 Dl_info dlinfo;
1723 struct _address_to_library_name data;
1724
1725 // There is a bug in old glibc dladdr() implementation that it could resolve
1726 // to wrong library name if the .so file has a base address != NULL. Here
1727 // we iterate through the program headers of all loaded libraries to find
1728 // out which library 'addr' really belongs to. This workaround can be
1729 // removed once the minimum requirement for glibc is moved to 2.3.x.
1730 data.addr = addr;
1731 data.fname = buf;
1732 data.buflen = buflen;
1733 data.base = NULL;
1734 int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data);
1735
1736 if (rslt) {
1737 // buf already contains library name
1738 if (offset) *offset = addr - data.base;
1739 return true;
1740 }
1741 if (dladdr((void*)addr, &dlinfo) != 0) {
1742 if (dlinfo.dli_fname != NULL) {
1743 jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname);
1744 }
1745 if (dlinfo.dli_fbase != NULL && offset != NULL) {
1746 *offset = addr - (address)dlinfo.dli_fbase;
1747 }
1748 return true;
1749 }
1750
1751 buf[0] = '\0';
1752 if (offset) *offset = -1;
1753 return false;
1754 }
1755
1756 // Loads .dll/.so and
1757 // in case of error it checks if .dll/.so was built for the
1758 // same architecture as Hotspot is running on
1759
1760
1761 // Remember the stack's state. The Linux dynamic linker will change
1762 // the stack to 'executable' at most once, so we must safepoint only once.
1763 bool os::Linux::_stack_is_executable = false;
1764
1765 // VM operation that loads a library. This is necessary if stack protection
1766 // of the Java stacks can be lost during loading the library. If we
1767 // do not stop the Java threads, they can stack overflow before the stacks
1768 // are protected again.
1769 class VM_LinuxDllLoad: public VM_Operation {
1770 private:
1771 const char *_filename;
1772 char *_ebuf;
1773 int _ebuflen;
1774 void *_lib;
1775 public:
1776 VM_LinuxDllLoad(const char *fn, char *ebuf, int ebuflen) :
1777 _filename(fn), _ebuf(ebuf), _ebuflen(ebuflen), _lib(NULL) {}
1778 VMOp_Type type() const { return VMOp_LinuxDllLoad; }
1779 void doit() {
1780 _lib = os::Linux::dll_load_in_vmthread(_filename, _ebuf, _ebuflen);
1781 os::Linux::_stack_is_executable = true;
1782 }
1783 void* loaded_library() { return _lib; }
1784 };
1785
1786 void * os::dll_load(const char *filename, char *ebuf, int ebuflen)
1787 {
1788 void * result = NULL;
1789 bool load_attempted = false;
1790
1791 // Check whether the library to load might change execution rights
1792 // of the stack. If they are changed, the protection of the stack
1793 // guard pages will be lost. We need a safepoint to fix this.
1794 //
1795 // See Linux man page execstack(8) for more info.
1796 if (os::uses_stack_guard_pages() && !os::Linux::_stack_is_executable) {
1797 ElfFile ef(filename);
1798 if (!ef.specifies_noexecstack()) {
1799 if (!is_init_completed()) {
1800 os::Linux::_stack_is_executable = true;
1801 // This is OK - No Java threads have been created yet, and hence no
1802 // stack guard pages to fix.
1803 //
1804 // This should happen only when you are building JDK7 using a very
1805 // old version of JDK6 (e.g., with JPRT) and running test_gamma.
1806 //
1807 // Dynamic loader will make all stacks executable after
1808 // this function returns, and will not do that again.
1809 assert(Threads::first() == NULL, "no Java threads should exist yet.");
1810 } else {
1811 warning("You have loaded library %s which might have disabled stack guard. "
1812 "The VM will try to fix the stack guard now.\n"
1813 "It's highly recommended that you fix the library with "
1814 "'execstack -c <libfile>', or link it with '-z noexecstack'.",
1815 filename);
1816
1817 assert(Thread::current()->is_Java_thread(), "must be Java thread");
1818 JavaThread *jt = JavaThread::current();
1819 if (jt->thread_state() != _thread_in_native) {
1820 // This happens when a compiler thread tries to load a hsdis-<arch>.so file
1821 // that requires ExecStack. Cannot enter safe point. Let's give up.
1822 warning("Unable to fix stack guard. Giving up.");
1823 } else {
1824 if (!LoadExecStackDllInVMThread) {
1825 // This is for the case where the DLL has an static
1826 // constructor function that executes JNI code. We cannot
1827 // load such DLLs in the VMThread.
1828 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen);
1829 }
1830
1831 ThreadInVMfromNative tiv(jt);
1832 debug_only(VMNativeEntryWrapper vew;)
1833
1834 VM_LinuxDllLoad op(filename, ebuf, ebuflen);
1835 VMThread::execute(&op);
1836 if (LoadExecStackDllInVMThread) {
1837 result = op.loaded_library();
1838 }
1839 load_attempted = true;
1840 }
1841 }
1842 }
1843 }
1844
1845 if (!load_attempted) {
1846 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen);
1847 }
1848
1849 if (result != NULL) {
1850 // Successful loading
1851 return result;
1852 }
1853
1854 Elf32_Ehdr elf_head;
1855 int diag_msg_max_length=ebuflen-strlen(ebuf);
1856 char* diag_msg_buf=ebuf+strlen(ebuf);
1857
1858 if (diag_msg_max_length==0) {
1859 // No more space in ebuf for additional diagnostics message
1860 return NULL;
1861 }
1862
1863
1864 int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK);
1865
1866 if (file_descriptor < 0) {
1867 // Can't open library, report dlerror() message
1868 return NULL;
1869 }
1870
1871 bool failed_to_read_elf_head=
1872 (sizeof(elf_head)!=
1873 (::read(file_descriptor, &elf_head,sizeof(elf_head)))) ;
1874
1875 ::close(file_descriptor);
1876 if (failed_to_read_elf_head) {
1877 // file i/o error - report dlerror() msg
1878 return NULL;
1879 }
1880
1881 typedef struct {
1882 Elf32_Half code; // Actual value as defined in elf.h
1883 Elf32_Half compat_class; // Compatibility of archs at VM's sense
1884 char elf_class; // 32 or 64 bit
1885 char endianess; // MSB or LSB
1886 char* name; // String representation
1887 } arch_t;
1888
1889 #ifndef EM_486
1890 #define EM_486 6 /* Intel 80486 */
1891 #endif
1892
1893 static const arch_t arch_array[]={
1894 {EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
1895 {EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
1896 {EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"},
1897 {EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"},
1898 {EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
1899 {EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
1900 {EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"},
1901 {EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"},
1902 #if defined(VM_LITTLE_ENDIAN)
1903 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2LSB, (char*)"Power PC 64"},
1904 #else
1905 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"},
1906 #endif
1907 {EM_ARM, EM_ARM, ELFCLASS32, ELFDATA2LSB, (char*)"ARM"},
1908 {EM_S390, EM_S390, ELFCLASSNONE, ELFDATA2MSB, (char*)"IBM System/390"},
1909 {EM_ALPHA, EM_ALPHA, ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"},
1910 {EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"},
1911 {EM_MIPS, EM_MIPS, ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"},
1912 {EM_PARISC, EM_PARISC, ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"},
1913 {EM_68K, EM_68K, ELFCLASS32, ELFDATA2MSB, (char*)"M68k"}
1914 };
1915
1916 #if (defined IA32)
1917 static Elf32_Half running_arch_code=EM_386;
1918 #elif (defined AMD64)
1919 static Elf32_Half running_arch_code=EM_X86_64;
1920 #elif (defined IA64)
1921 static Elf32_Half running_arch_code=EM_IA_64;
1922 #elif (defined __sparc) && (defined _LP64)
1923 static Elf32_Half running_arch_code=EM_SPARCV9;
1924 #elif (defined __sparc) && (!defined _LP64)
1925 static Elf32_Half running_arch_code=EM_SPARC;
1926 #elif (defined __powerpc64__)
1927 static Elf32_Half running_arch_code=EM_PPC64;
1928 #elif (defined __powerpc__)
1929 static Elf32_Half running_arch_code=EM_PPC;
1930 #elif (defined ARM)
1931 static Elf32_Half running_arch_code=EM_ARM;
1932 #elif (defined S390)
1933 static Elf32_Half running_arch_code=EM_S390;
1934 #elif (defined ALPHA)
1935 static Elf32_Half running_arch_code=EM_ALPHA;
1936 #elif (defined MIPSEL)
1937 static Elf32_Half running_arch_code=EM_MIPS_RS3_LE;
1938 #elif (defined PARISC)
1939 static Elf32_Half running_arch_code=EM_PARISC;
1940 #elif (defined MIPS)
1941 static Elf32_Half running_arch_code=EM_MIPS;
1942 #elif (defined M68K)
1943 static Elf32_Half running_arch_code=EM_68K;
1944 #else
1945 #error Method os::dll_load requires that one of following is defined:\
1946 IA32, AMD64, IA64, __sparc, __powerpc__, ARM, S390, ALPHA, MIPS, MIPSEL, PARISC, M68K
1947 #endif
1948
1949 // Identify compatability class for VM's architecture and library's architecture
1950 // Obtain string descriptions for architectures
1951
1952 arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL};
1953 int running_arch_index=-1;
1954
1955 for (unsigned int i=0 ; i < ARRAY_SIZE(arch_array) ; i++ ) {
1956 if (running_arch_code == arch_array[i].code) {
1957 running_arch_index = i;
1958 }
1959 if (lib_arch.code == arch_array[i].code) {
1960 lib_arch.compat_class = arch_array[i].compat_class;
1961 lib_arch.name = arch_array[i].name;
1962 }
1963 }
1964
1965 assert(running_arch_index != -1,
1966 "Didn't find running architecture code (running_arch_code) in arch_array");
1967 if (running_arch_index == -1) {
1968 // Even though running architecture detection failed
1969 // we may still continue with reporting dlerror() message
1970 return NULL;
1971 }
1972
1973 if (lib_arch.endianess != arch_array[running_arch_index].endianess) {
1974 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)");
1975 return NULL;
1976 }
1977
1978 #ifndef S390
1979 if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) {
1980 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)");
1981 return NULL;
1982 }
1983 #endif // !S390
1984
1985 if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) {
1986 if ( lib_arch.name!=NULL ) {
1987 ::snprintf(diag_msg_buf, diag_msg_max_length-1,
1988 " (Possible cause: can't load %s-bit .so on a %s-bit platform)",
1989 lib_arch.name, arch_array[running_arch_index].name);
1990 } else {
1991 ::snprintf(diag_msg_buf, diag_msg_max_length-1,
1992 " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)",
1993 lib_arch.code,
1994 arch_array[running_arch_index].name);
1995 }
1996 }
1997
1998 return NULL;
1999 }
2000
2001 void * os::Linux::dlopen_helper(const char *filename, char *ebuf, int ebuflen) {
2002 void * result = ::dlopen(filename, RTLD_LAZY);
2003 if (result == NULL) {
2004 ::strncpy(ebuf, ::dlerror(), ebuflen - 1);
2005 ebuf[ebuflen-1] = '\0';
2006 }
2007 return result;
2008 }
2009
2010 void * os::Linux::dll_load_in_vmthread(const char *filename, char *ebuf, int ebuflen) {
2011 void * result = NULL;
2012 if (LoadExecStackDllInVMThread) {
2013 result = dlopen_helper(filename, ebuf, ebuflen);
2014 }
2015
2016 // Since 7019808, libjvm.so is linked with -noexecstack. If the VM loads a
2017 // library that requires an executable stack, or which does not have this
2018 // stack attribute set, dlopen changes the stack attribute to executable. The
2019 // read protection of the guard pages gets lost.
2020 //
2021 // Need to check _stack_is_executable again as multiple VM_LinuxDllLoad
2022 // may have been queued at the same time.
2023
2024 if (!_stack_is_executable) {
2025 JavaThread *jt = Threads::first();
2026
2027 while (jt) {
2028 if (!jt->stack_guard_zone_unused() && // Stack not yet fully initialized
2029 jt->stack_yellow_zone_enabled()) { // No pending stack overflow exceptions
2030 if (!os::guard_memory((char *) jt->stack_red_zone_base() - jt->stack_red_zone_size(),
2031 jt->stack_yellow_zone_size() + jt->stack_red_zone_size())) {
2032 warning("Attempt to reguard stack yellow zone failed.");
2033 }
2034 }
2035 jt = jt->next();
2036 }
2037 }
2038
2039 return result;
2040 }
2041
2042 /*
2043 * glibc-2.0 libdl is not MT safe. If you are building with any glibc,
2044 * chances are you might want to run the generated bits against glibc-2.0
2045 * libdl.so, so always use locking for any version of glibc.
2046 */
2047 void* os::dll_lookup(void* handle, const char* name) {
2048 pthread_mutex_lock(&dl_mutex);
2049 void* res = dlsym(handle, name);
2050 pthread_mutex_unlock(&dl_mutex);
2051 return res;
2052 }
2053
2054 void* os::get_default_process_handle() {
2055 return (void*)::dlopen(NULL, RTLD_LAZY);
2056 }
2057
2058 static bool _print_ascii_file(const char* filename, outputStream* st) {
2059 int fd = ::open(filename, O_RDONLY);
2060 if (fd == -1) {
2061 return false;
2062 }
2063
2064 char buf[32];
2065 int bytes;
2066 while ((bytes = ::read(fd, buf, sizeof(buf))) > 0) {
2067 st->print_raw(buf, bytes);
2068 }
2069
2070 ::close(fd);
2071
2072 return true;
2073 }
2074
2075 void os::print_dll_info(outputStream *st) {
2076 st->print_cr("Dynamic libraries:");
2077
2078 char fname[32];
2079 pid_t pid = os::Linux::gettid();
2080
2081 jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid);
2082
2083 if (!_print_ascii_file(fname, st)) {
2084 st->print("Can not get library information for pid = %d\n", pid);
2085 }
2086 }
2087
2088 void os::print_os_info_brief(outputStream* st) {
2089 os::Linux::print_distro_info(st);
2090
2091 os::Posix::print_uname_info(st);
2092
2093 os::Linux::print_libversion_info(st);
2094
2095 }
2096
2097 void os::print_os_info(outputStream* st) {
2098 st->print("OS:");
2099
2100 os::Linux::print_distro_info(st);
2101
2102 os::Posix::print_uname_info(st);
2103
2104 // Print warning if unsafe chroot environment detected
2105 if (unsafe_chroot_detected) {
2106 st->print("WARNING!! ");
2107 st->print_cr("%s", unstable_chroot_error);
2108 }
2109
2110 os::Linux::print_libversion_info(st);
2111
2112 os::Posix::print_rlimit_info(st);
2113
2114 os::Posix::print_load_average(st);
2115
2116 os::Linux::print_full_memory_info(st);
2117 }
2118
2119 // Try to identify popular distros.
2120 // Most Linux distributions have a /etc/XXX-release file, which contains
2121 // the OS version string. Newer Linux distributions have a /etc/lsb-release
2122 // file that also contains the OS version string. Some have more than one
2123 // /etc/XXX-release file (e.g. Mandrake has both /etc/mandrake-release and
2124 // /etc/redhat-release.), so the order is important.
2125 // Any Linux that is based on Redhat (i.e. Oracle, Mandrake, Sun JDS...) have
2126 // their own specific XXX-release file as well as a redhat-release file.
2127 // Because of this the XXX-release file needs to be searched for before the
2128 // redhat-release file.
2129 // Since Red Hat has a lsb-release file that is not very descriptive the
2130 // search for redhat-release needs to be before lsb-release.
2131 // Since the lsb-release file is the new standard it needs to be searched
2132 // before the older style release files.
2133 // Searching system-release (Red Hat) and os-release (other Linuxes) are a
2134 // next to last resort. The os-release file is a new standard that contains
2135 // distribution information and the system-release file seems to be an old
2136 // standard that has been replaced by the lsb-release and os-release files.
2137 // Searching for the debian_version file is the last resort. It contains
2138 // an informative string like "6.0.6" or "wheezy/sid". Because of this
2139 // "Debian " is printed before the contents of the debian_version file.
2140 void os::Linux::print_distro_info(outputStream* st) {
2141 if (!_print_ascii_file("/etc/oracle-release", st) &&
2142 !_print_ascii_file("/etc/mandriva-release", st) &&
2143 !_print_ascii_file("/etc/mandrake-release", st) &&
2144 !_print_ascii_file("/etc/sun-release", st) &&
2145 !_print_ascii_file("/etc/redhat-release", st) &&
2146 !_print_ascii_file("/etc/lsb-release", st) &&
2147 !_print_ascii_file("/etc/SuSE-release", st) &&
2148 !_print_ascii_file("/etc/turbolinux-release", st) &&
2149 !_print_ascii_file("/etc/gentoo-release", st) &&
2150 !_print_ascii_file("/etc/ltib-release", st) &&
2151 !_print_ascii_file("/etc/angstrom-version", st) &&
2152 !_print_ascii_file("/etc/system-release", st) &&
2153 !_print_ascii_file("/etc/os-release", st)) {
2154
2155 if (file_exists("/etc/debian_version")) {
2156 st->print("Debian ");
2157 _print_ascii_file("/etc/debian_version", st);
2158 } else {
2159 st->print("Linux");
2160 }
2161 }
2162 st->cr();
2163 }
2164
2165 void os::Linux::print_libversion_info(outputStream* st) {
2166 // libc, pthread
2167 st->print("libc:");
2168 st->print("%s ", os::Linux::glibc_version());
2169 st->print("%s ", os::Linux::libpthread_version());
2170 if (os::Linux::is_LinuxThreads()) {
2171 st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed");
2172 }
2173 st->cr();
2174 }
2175
2176 void os::Linux::print_full_memory_info(outputStream* st) {
2177 st->print("\n/proc/meminfo:\n");
2178 _print_ascii_file("/proc/meminfo", st);
2179 st->cr();
2180 }
2181
2182 void os::print_memory_info(outputStream* st) {
2183
2184 st->print("Memory:");
2185 st->print(" %dk page", os::vm_page_size()>>10);
2186
2187 // values in struct sysinfo are "unsigned long"
2188 struct sysinfo si;
2189 sysinfo(&si);
2190
2191 st->print(", physical " UINT64_FORMAT "k",
2192 os::physical_memory() >> 10);
2193 st->print("(" UINT64_FORMAT "k free)",
2194 os::available_memory() >> 10);
2195 st->print(", swap " UINT64_FORMAT "k",
2196 ((jlong)si.totalswap * si.mem_unit) >> 10);
2197 st->print("(" UINT64_FORMAT "k free)",
2198 ((jlong)si.freeswap * si.mem_unit) >> 10);
2199 st->cr();
2200 }
2201
2202 void os::pd_print_cpu_info(outputStream* st) {
2203 st->print("\n/proc/cpuinfo:\n");
2204 if (!_print_ascii_file("/proc/cpuinfo", st)) {
2205 st->print(" <Not Available>");
2206 }
2207 st->cr();
2208 }
2209
2210 void os::print_siginfo(outputStream* st, void* siginfo) {
2211 const siginfo_t* si = (const siginfo_t*)siginfo;
2212
2213 os::Posix::print_siginfo_brief(st, si);
2214 #if INCLUDE_CDS
2215 if (si && (si->si_signo == SIGBUS || si->si_signo == SIGSEGV) &&
2216 UseSharedSpaces) {
2217 FileMapInfo* mapinfo = FileMapInfo::current_info();
2218 if (mapinfo->is_in_shared_space(si->si_addr)) {
2219 st->print("\n\nError accessing class data sharing archive." \
2220 " Mapped file inaccessible during execution, " \
2221 " possible disk/network problem.");
2222 }
2223 }
2224 #endif
2225 st->cr();
2226 }
2227
2228
2229 static void print_signal_handler(outputStream* st, int sig,
2230 char* buf, size_t buflen);
2231
2232 void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) {
2233 st->print_cr("Signal Handlers:");
2234 print_signal_handler(st, SIGSEGV, buf, buflen);
2235 print_signal_handler(st, SIGBUS , buf, buflen);
2236 print_signal_handler(st, SIGFPE , buf, buflen);
2237 print_signal_handler(st, SIGPIPE, buf, buflen);
2238 print_signal_handler(st, SIGXFSZ, buf, buflen);
2239 print_signal_handler(st, SIGILL , buf, buflen);
2240 print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen);
2241 print_signal_handler(st, SR_signum, buf, buflen);
2242 print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen);
2243 print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen);
2244 print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen);
2245 print_signal_handler(st, BREAK_SIGNAL, buf, buflen);
2246 #if defined(PPC64)
2247 print_signal_handler(st, SIGTRAP, buf, buflen);
2248 #endif
2249 }
2250
2251 static char saved_jvm_path[MAXPATHLEN] = {0};
2252
2253 // Find the full path to the current module, libjvm.so
2254 void os::jvm_path(char *buf, jint buflen) {
2255 // Error checking.
2256 if (buflen < MAXPATHLEN) {
2257 assert(false, "must use a large-enough buffer");
2258 buf[0] = '\0';
2259 return;
2260 }
2261 // Lazy resolve the path to current module.
2262 if (saved_jvm_path[0] != 0) {
2263 strcpy(buf, saved_jvm_path);
2264 return;
2265 }
2266
2267 char dli_fname[MAXPATHLEN];
2268 bool ret = dll_address_to_library_name(
2269 CAST_FROM_FN_PTR(address, os::jvm_path),
2270 dli_fname, sizeof(dli_fname), NULL);
2271 assert(ret, "cannot locate libjvm");
2272 char *rp = NULL;
2273 if (ret && dli_fname[0] != '\0') {
2274 rp = realpath(dli_fname, buf);
2275 }
2276 if (rp == NULL)
2277 return;
2278
2279 if (Arguments::created_by_gamma_launcher()) {
2280 // Support for the gamma launcher. Typical value for buf is
2281 // "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so". If "/jre/lib/" appears at
2282 // the right place in the string, then assume we are installed in a JDK and
2283 // we're done. Otherwise, check for a JAVA_HOME environment variable and fix
2284 // up the path so it looks like libjvm.so is installed there (append a
2285 // fake suffix hotspot/libjvm.so).
2286 const char *p = buf + strlen(buf) - 1;
2287 for (int count = 0; p > buf && count < 5; ++count) {
2288 for (--p; p > buf && *p != '/'; --p)
2289 /* empty */ ;
2290 }
2291
2292 if (strncmp(p, "/jre/lib/", 9) != 0) {
2293 // Look for JAVA_HOME in the environment.
2294 char* java_home_var = ::getenv("JAVA_HOME");
2295 if (java_home_var != NULL && java_home_var[0] != 0) {
2296 char* jrelib_p;
2297 int len;
2298
2299 // Check the current module name "libjvm.so".
2300 p = strrchr(buf, '/');
2301 assert(strstr(p, "/libjvm") == p, "invalid library name");
2302
2303 rp = realpath(java_home_var, buf);
2304 if (rp == NULL)
2305 return;
2306
2307 // determine if this is a legacy image or modules image
2308 // modules image doesn't have "jre" subdirectory
2309 len = strlen(buf);
2310 assert(len < buflen, "Ran out of buffer room");
2311 jrelib_p = buf + len;
2312 snprintf(jrelib_p, buflen-len, "/jre/lib/%s", cpu_arch);
2313 if (0 != access(buf, F_OK)) {
2314 snprintf(jrelib_p, buflen-len, "/lib/%s", cpu_arch);
2315 }
2316
2317 if (0 == access(buf, F_OK)) {
2318 // Use current module name "libjvm.so"
2319 len = strlen(buf);
2320 snprintf(buf + len, buflen-len, "/hotspot/libjvm.so");
2321 } else {
2322 // Go back to path of .so
2323 rp = realpath(dli_fname, buf);
2324 if (rp == NULL)
2325 return;
2326 }
2327 }
2328 }
2329 }
2330
2331 strncpy(saved_jvm_path, buf, MAXPATHLEN);
2332 }
2333
2334 void os::print_jni_name_prefix_on(outputStream* st, int args_size) {
2335 // no prefix required, not even "_"
2336 }
2337
2338 void os::print_jni_name_suffix_on(outputStream* st, int args_size) {
2339 // no suffix required
2340 }
2341
2342 ////////////////////////////////////////////////////////////////////////////////
2343 // sun.misc.Signal support
2344
2345 static volatile jint sigint_count = 0;
2346
2347 static void
2348 UserHandler(int sig, void *siginfo, void *context) {
2349 // 4511530 - sem_post is serialized and handled by the manager thread. When
2350 // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We
2351 // don't want to flood the manager thread with sem_post requests.
2352 if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1)
2353 return;
2354
2355 // Ctrl-C is pressed during error reporting, likely because the error
2356 // handler fails to abort. Let VM die immediately.
2357 if (sig == SIGINT && is_error_reported()) {
2358 os::die();
2359 }
2360
2361 os::signal_notify(sig);
2362 }
2363
2364 void* os::user_handler() {
2365 return CAST_FROM_FN_PTR(void*, UserHandler);
2366 }
2367
2368 class Semaphore : public StackObj {
2369 public:
2370 Semaphore();
2371 ~Semaphore();
2372 void signal();
2373 void wait();
2374 bool trywait();
2375 bool timedwait(unsigned int sec, int nsec);
2376 private:
2377 sem_t _semaphore;
2378 };
2379
2380 Semaphore::Semaphore() {
2381 sem_init(&_semaphore, 0, 0);
2382 }
2383
2384 Semaphore::~Semaphore() {
2385 sem_destroy(&_semaphore);
2386 }
2387
2388 void Semaphore::signal() {
2389 sem_post(&_semaphore);
2390 }
2391
2392 void Semaphore::wait() {
2393 sem_wait(&_semaphore);
2394 }
2395
2396 bool Semaphore::trywait() {
2397 return sem_trywait(&_semaphore) == 0;
2398 }
2399
2400 bool Semaphore::timedwait(unsigned int sec, int nsec) {
2401
2402 struct timespec ts;
2403 // Semaphore's are always associated with CLOCK_REALTIME
2404 os::Linux::clock_gettime(CLOCK_REALTIME, &ts);
2405 // see unpackTime for discussion on overflow checking
2406 if (sec >= MAX_SECS) {
2407 ts.tv_sec += MAX_SECS;
2408 ts.tv_nsec = 0;
2409 } else {
2410 ts.tv_sec += sec;
2411 ts.tv_nsec += nsec;
2412 if (ts.tv_nsec >= NANOSECS_PER_SEC) {
2413 ts.tv_nsec -= NANOSECS_PER_SEC;
2414 ++ts.tv_sec; // note: this must be <= max_secs
2415 }
2416 }
2417
2418 while (1) {
2419 int result = sem_timedwait(&_semaphore, &ts);
2420 if (result == 0) {
2421 return true;
2422 } else if (errno == EINTR) {
2423 continue;
2424 } else if (errno == ETIMEDOUT) {
2425 return false;
2426 } else {
2427 return false;
2428 }
2429 }
2430 }
2431
2432 extern "C" {
2433 typedef void (*sa_handler_t)(int);
2434 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *);
2435 }
2436
2437 void* os::signal(int signal_number, void* handler) {
2438 struct sigaction sigAct, oldSigAct;
2439
2440 sigfillset(&(sigAct.sa_mask));
2441 sigAct.sa_flags = SA_RESTART|SA_SIGINFO;
2442 sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler);
2443
2444 if (sigaction(signal_number, &sigAct, &oldSigAct)) {
2445 // -1 means registration failed
2446 return (void *)-1;
2447 }
2448
2449 return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler);
2450 }
2451
2452 void os::signal_raise(int signal_number) {
2453 ::raise(signal_number);
2454 }
2455
2456 /*
2457 * The following code is moved from os.cpp for making this
2458 * code platform specific, which it is by its very nature.
2459 */
2460
2461 // Will be modified when max signal is changed to be dynamic
2462 int os::sigexitnum_pd() {
2463 return NSIG;
2464 }
2465
2466 // a counter for each possible signal value
2467 static volatile jint pending_signals[NSIG+1] = { 0 };
2468
2469 // Linux(POSIX) specific hand shaking semaphore.
2470 static sem_t sig_sem;
2471 static Semaphore sr_semaphore;
2472
2473 void os::signal_init_pd() {
2474 // Initialize signal structures
2475 ::memset((void*)pending_signals, 0, sizeof(pending_signals));
2476
2477 // Initialize signal semaphore
2478 ::sem_init(&sig_sem, 0, 0);
2479 }
2480
2481 void os::signal_notify(int sig) {
2482 Atomic::inc(&pending_signals[sig]);
2483 ::sem_post(&sig_sem);
2484 }
2485
2486 static int check_pending_signals(bool wait) {
2487 Atomic::store(0, &sigint_count);
2488 for (;;) {
2489 for (int i = 0; i < NSIG + 1; i++) {
2490 jint n = pending_signals[i];
2491 if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) {
2492 return i;
2493 }
2494 }
2495 if (!wait) {
2496 return -1;
2497 }
2498 JavaThread *thread = JavaThread::current();
2499 ThreadBlockInVM tbivm(thread);
2500
2501 bool threadIsSuspended;
2502 do {
2503 thread->set_suspend_equivalent();
2504 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
2505 ::sem_wait(&sig_sem);
2506
2507 // were we externally suspended while we were waiting?
2508 threadIsSuspended = thread->handle_special_suspend_equivalent_condition();
2509 if (threadIsSuspended) {
2510 //
2511 // The semaphore has been incremented, but while we were waiting
2512 // another thread suspended us. We don't want to continue running
2513 // while suspended because that would surprise the thread that
2514 // suspended us.
2515 //
2516 ::sem_post(&sig_sem);
2517
2518 thread->java_suspend_self();
2519 }
2520 } while (threadIsSuspended);
2521 }
2522 }
2523
2524 int os::signal_lookup() {
2525 return check_pending_signals(false);
2526 }
2527
2528 int os::signal_wait() {
2529 return check_pending_signals(true);
2530 }
2531
2532 ////////////////////////////////////////////////////////////////////////////////
2533 // Virtual Memory
2534
2535 int os::vm_page_size() {
2536 // Seems redundant as all get out
2537 assert(os::Linux::page_size() != -1, "must call os::init");
2538 return os::Linux::page_size();
2539 }
2540
2541 // Solaris allocates memory by pages.
2542 int os::vm_allocation_granularity() {
2543 assert(os::Linux::page_size() != -1, "must call os::init");
2544 return os::Linux::page_size();
2545 }
2546
2547 // Rationale behind this function:
2548 // current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable
2549 // mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get
2550 // samples for JITted code. Here we create private executable mapping over the code cache
2551 // and then we can use standard (well, almost, as mapping can change) way to provide
2552 // info for the reporting script by storing timestamp and location of symbol
2553 void linux_wrap_code(char* base, size_t size) {
2554 static volatile jint cnt = 0;
2555
2556 if (!UseOprofile) {
2557 return;
2558 }
2559
2560 char buf[PATH_MAX+1];
2561 int num = Atomic::add(1, &cnt);
2562
2563 snprintf(buf, sizeof(buf), "%s/hs-vm-%d-%d",
2564 os::get_temp_directory(), os::current_process_id(), num);
2565 unlink(buf);
2566
2567 int fd = ::open(buf, O_CREAT | O_RDWR, S_IRWXU);
2568
2569 if (fd != -1) {
2570 off_t rv = ::lseek(fd, size-2, SEEK_SET);
2571 if (rv != (off_t)-1) {
2572 if (::write(fd, "", 1) == 1) {
2573 mmap(base, size,
2574 PROT_READ|PROT_WRITE|PROT_EXEC,
2575 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0);
2576 }
2577 }
2578 ::close(fd);
2579 unlink(buf);
2580 }
2581 }
2582
2583 static bool recoverable_mmap_error(int err) {
2584 // See if the error is one we can let the caller handle. This
2585 // list of errno values comes from JBS-6843484. I can't find a
2586 // Linux man page that documents this specific set of errno
2587 // values so while this list currently matches Solaris, it may
2588 // change as we gain experience with this failure mode.
2589 switch (err) {
2590 case EBADF:
2591 case EINVAL:
2592 case ENOTSUP:
2593 // let the caller deal with these errors
2594 return true;
2595
2596 default:
2597 // Any remaining errors on this OS can cause our reserved mapping
2598 // to be lost. That can cause confusion where different data
2599 // structures think they have the same memory mapped. The worst
2600 // scenario is if both the VM and a library think they have the
2601 // same memory mapped.
2602 return false;
2603 }
2604 }
2605
2606 static void warn_fail_commit_memory(char* addr, size_t size, bool exec,
2607 int err) {
2608 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT
2609 ", %d) failed; error='%s' (errno=%d)", addr, size, exec,
2610 strerror(err), err);
2611 }
2612
2613 static void warn_fail_commit_memory(char* addr, size_t size,
2614 size_t alignment_hint, bool exec,
2615 int err) {
2616 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT
2617 ", " SIZE_FORMAT ", %d) failed; error='%s' (errno=%d)", addr, size,
2618 alignment_hint, exec, strerror(err), err);
2619 }
2620
2621 // NOTE: Linux kernel does not really reserve the pages for us.
2622 // All it does is to check if there are enough free pages
2623 // left at the time of mmap(). This could be a potential
2624 // problem.
2625 int os::Linux::commit_memory_impl(char* addr, size_t size, bool exec) {
2626 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
2627 uintptr_t res = (uintptr_t) ::mmap(addr, size, prot,
2628 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0);
2629 if (res != (uintptr_t) MAP_FAILED) {
2630 if (UseNUMAInterleaving) {
2631 numa_make_global(addr, size);
2632 }
2633 return 0;
2634 }
2635
2636 int err = errno; // save errno from mmap() call above
2637
2638 if (!recoverable_mmap_error(err)) {
2639 warn_fail_commit_memory(addr, size, exec, err);
2640 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, "committing reserved memory.");
2641 }
2642
2643 return err;
2644 }
2645
2646 bool os::pd_commit_memory(char* addr, size_t size, bool exec) {
2647 return os::Linux::commit_memory_impl(addr, size, exec) == 0;
2648 }
2649
2650 void os::pd_commit_memory_or_exit(char* addr, size_t size, bool exec,
2651 const char* mesg) {
2652 assert(mesg != NULL, "mesg must be specified");
2653 int err = os::Linux::commit_memory_impl(addr, size, exec);
2654 if (err != 0) {
2655 // the caller wants all commit errors to exit with the specified mesg:
2656 warn_fail_commit_memory(addr, size, exec, err);
2657 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg);
2658 }
2659 }
2660
2661 // Define MAP_HUGETLB here so we can build HotSpot on old systems.
2662 #ifndef MAP_HUGETLB
2663 #define MAP_HUGETLB 0x40000
2664 #endif
2665
2666 // Define MADV_HUGEPAGE here so we can build HotSpot on old systems.
2667 #ifndef MADV_HUGEPAGE
2668 #define MADV_HUGEPAGE 14
2669 #endif
2670
2671 int os::Linux::commit_memory_impl(char* addr, size_t size,
2672 size_t alignment_hint, bool exec) {
2673 int err = os::Linux::commit_memory_impl(addr, size, exec);
2674 if (err == 0) {
2675 realign_memory(addr, size, alignment_hint);
2676 }
2677 return err;
2678 }
2679
2680 bool os::pd_commit_memory(char* addr, size_t size, size_t alignment_hint,
2681 bool exec) {
2682 return os::Linux::commit_memory_impl(addr, size, alignment_hint, exec) == 0;
2683 }
2684
2685 void os::pd_commit_memory_or_exit(char* addr, size_t size,
2686 size_t alignment_hint, bool exec,
2687 const char* mesg) {
2688 assert(mesg != NULL, "mesg must be specified");
2689 int err = os::Linux::commit_memory_impl(addr, size, alignment_hint, exec);
2690 if (err != 0) {
2691 // the caller wants all commit errors to exit with the specified mesg:
2692 warn_fail_commit_memory(addr, size, alignment_hint, exec, err);
2693 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg);
2694 }
2695 }
2696
2697 void os::pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint) {
2698 if (UseTransparentHugePages && alignment_hint > (size_t)vm_page_size()) {
2699 // We don't check the return value: madvise(MADV_HUGEPAGE) may not
2700 // be supported or the memory may already be backed by huge pages.
2701 ::madvise(addr, bytes, MADV_HUGEPAGE);
2702 }
2703 }
2704
2705 void os::pd_free_memory(char *addr, size_t bytes, size_t alignment_hint) {
2706 // This method works by doing an mmap over an existing mmaping and effectively discarding
2707 // the existing pages. However it won't work for SHM-based large pages that cannot be
2708 // uncommitted at all. We don't do anything in this case to avoid creating a segment with
2709 // small pages on top of the SHM segment. This method always works for small pages, so we
2710 // allow that in any case.
2711 if (alignment_hint <= (size_t)os::vm_page_size() || can_commit_large_page_memory()) {
2712 commit_memory(addr, bytes, alignment_hint, !ExecMem);
2713 }
2714 }
2715
2716 void os::numa_make_global(char *addr, size_t bytes) {
2717 Linux::numa_interleave_memory(addr, bytes);
2718 }
2719
2720 // Define for numa_set_bind_policy(int). Setting the argument to 0 will set the
2721 // bind policy to MPOL_PREFERRED for the current thread.
2722 #define USE_MPOL_PREFERRED 0
2723
2724 void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) {
2725 // To make NUMA and large pages more robust when both enabled, we need to ease
2726 // the requirements on where the memory should be allocated. MPOL_BIND is the
2727 // default policy and it will force memory to be allocated on the specified
2728 // node. Changing this to MPOL_PREFERRED will prefer to allocate the memory on
2729 // the specified node, but will not force it. Using this policy will prevent
2730 // getting SIGBUS when trying to allocate large pages on NUMA nodes with no
2731 // free large pages.
2732 Linux::numa_set_bind_policy(USE_MPOL_PREFERRED);
2733 Linux::numa_tonode_memory(addr, bytes, lgrp_hint);
2734 }
2735
2736 bool os::numa_topology_changed() { return false; }
2737
2738 size_t os::numa_get_groups_num() {
2739 // Return just the number of nodes in which it's possible to allocate memory
2740 // (in numa terminology, configured nodes).
2741 return Linux::numa_num_configured_nodes();
2742 }
2743
2744 int os::numa_get_group_id() {
2745 int cpu_id = Linux::sched_getcpu();
2746 if (cpu_id != -1) {
2747 int lgrp_id = Linux::get_node_by_cpu(cpu_id);
2748 if (lgrp_id != -1) {
2749 return lgrp_id;
2750 }
2751 }
2752 return 0;
2753 }
2754
2755 int os::Linux::get_existing_num_nodes() {
2756 size_t node;
2757 size_t highest_node_number = Linux::numa_max_node();
2758 int num_nodes = 0;
2759
2760 // Get the total number of nodes in the system including nodes without memory.
2761 for (node = 0; node <= highest_node_number; node++) {
2762 if (isnode_in_existing_nodes(node)) {
2763 num_nodes++;
2764 }
2765 }
2766 return num_nodes;
2767 }
2768
2769 size_t os::numa_get_leaf_groups(int *ids, size_t size) {
2770 size_t highest_node_number = Linux::numa_max_node();
2771 size_t i = 0;
2772
2773 // Map all node ids in which is possible to allocate memory. Also nodes are
2774 // not always consecutively available, i.e. available from 0 to the highest
2775 // node number.
2776 for (size_t node = 0; node <= highest_node_number; node++) {
2777 if (Linux::isnode_in_configured_nodes(node)) {
2778 ids[i++] = node;
2779 }
2780 }
2781 return i;
2782 }
2783
2784 bool os::get_page_info(char *start, page_info* info) {
2785 return false;
2786 }
2787
2788 char *os::scan_pages(char *start, char* end, page_info* page_expected, page_info* page_found) {
2789 return end;
2790 }
2791
2792
2793 int os::Linux::sched_getcpu_syscall(void) {
2794 unsigned int cpu = 0;
2795 int retval = -1;
2796
2797 #if defined(IA32)
2798 # ifndef SYS_getcpu
2799 # define SYS_getcpu 318
2800 # endif
2801 retval = syscall(SYS_getcpu, &cpu, NULL, NULL);
2802 #elif defined(AMD64)
2803 // Unfortunately we have to bring all these macros here from vsyscall.h
2804 // to be able to compile on old linuxes.
2805 # define __NR_vgetcpu 2
2806 # define VSYSCALL_START (-10UL << 20)
2807 # define VSYSCALL_SIZE 1024
2808 # define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr))
2809 typedef long (*vgetcpu_t)(unsigned int *cpu, unsigned int *node, unsigned long *tcache);
2810 vgetcpu_t vgetcpu = (vgetcpu_t)VSYSCALL_ADDR(__NR_vgetcpu);
2811 retval = vgetcpu(&cpu, NULL, NULL);
2812 #endif
2813
2814 return (retval == -1) ? retval : cpu;
2815 }
2816
2817 // Something to do with the numa-aware allocator needs these symbols
2818 extern "C" JNIEXPORT void numa_warn(int number, char *where, ...) { }
2819 extern "C" JNIEXPORT void numa_error(char *where) { }
2820 extern "C" JNIEXPORT int fork1() { return fork(); }
2821
2822
2823 // If we are running with libnuma version > 2, then we should
2824 // be trying to use symbols with versions 1.1
2825 // If we are running with earlier version, which did not have symbol versions,
2826 // we should use the base version.
2827 void* os::Linux::libnuma_dlsym(void* handle, const char *name) {
2828 void *f = dlvsym(handle, name, "libnuma_1.1");
2829 if (f == NULL) {
2830 f = dlsym(handle, name);
2831 }
2832 return f;
2833 }
2834
2835 bool os::Linux::libnuma_init() {
2836 // sched_getcpu() should be in libc.
2837 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t,
2838 dlsym(RTLD_DEFAULT, "sched_getcpu")));
2839
2840 // If it's not, try a direct syscall.
2841 if (sched_getcpu() == -1)
2842 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, (void*)&sched_getcpu_syscall));
2843
2844 if (sched_getcpu() != -1) { // Does it work?
2845 void *handle = dlopen("libnuma.so.1", RTLD_LAZY);
2846 if (handle != NULL) {
2847 set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t,
2848 libnuma_dlsym(handle, "numa_node_to_cpus")));
2849 set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t,
2850 libnuma_dlsym(handle, "numa_max_node")));
2851 set_numa_num_configured_nodes(CAST_TO_FN_PTR(numa_num_configured_nodes_func_t,
2852 libnuma_dlsym(handle, "numa_num_configured_nodes")));
2853 set_numa_available(CAST_TO_FN_PTR(numa_available_func_t,
2854 libnuma_dlsym(handle, "numa_available")));
2855 set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t,
2856 libnuma_dlsym(handle, "numa_tonode_memory")));
2857 set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t,
2858 libnuma_dlsym(handle, "numa_interleave_memory")));
2859 set_numa_set_bind_policy(CAST_TO_FN_PTR(numa_set_bind_policy_func_t,
2860 libnuma_dlsym(handle, "numa_set_bind_policy")));
2861 set_numa_bitmask_isbitset(CAST_TO_FN_PTR(numa_bitmask_isbitset_func_t,
2862 libnuma_dlsym(handle, "numa_bitmask_isbitset")));
2863 set_numa_distance(CAST_TO_FN_PTR(numa_distance_func_t,
2864 libnuma_dlsym(handle, "numa_distance")));
2865
2866 if (numa_available() != -1) {
2867 set_numa_all_nodes((unsigned long*)libnuma_dlsym(handle, "numa_all_nodes"));
2868 set_numa_all_nodes_ptr((struct bitmask **)libnuma_dlsym(handle, "numa_all_nodes_ptr"));
2869 set_numa_nodes_ptr((struct bitmask **)libnuma_dlsym(handle, "numa_nodes_ptr"));
2870 // Create an index -> node mapping, since nodes are not always consecutive
2871 _nindex_to_node = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<int>(0, true);
2872 rebuild_nindex_to_node_map();
2873 // Create a cpu -> node mapping
2874 _cpu_to_node = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<int>(0, true);
2875 rebuild_cpu_to_node_map();
2876 return true;
2877 }
2878 }
2879 }
2880 return false;
2881 }
2882
2883 void os::Linux::rebuild_nindex_to_node_map() {
2884 int highest_node_number = Linux::numa_max_node();
2885
2886 nindex_to_node()->clear();
2887 for (int node = 0; node <= highest_node_number; node++) {
2888 if (Linux::isnode_in_existing_nodes(node)) {
2889 nindex_to_node()->append(node);
2890 }
2891 }
2892 }
2893
2894 // rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id.
2895 // The table is later used in get_node_by_cpu().
2896 void os::Linux::rebuild_cpu_to_node_map() {
2897 const size_t NCPUS = 32768; // Since the buffer size computation is very obscure
2898 // in libnuma (possible values are starting from 16,
2899 // and continuing up with every other power of 2, but less
2900 // than the maximum number of CPUs supported by kernel), and
2901 // is a subject to change (in libnuma version 2 the requirements
2902 // are more reasonable) we'll just hardcode the number they use
2903 // in the library.
2904 const size_t BitsPerCLong = sizeof(long) * CHAR_BIT;
2905
2906 size_t cpu_num = processor_count();
2907 size_t cpu_map_size = NCPUS / BitsPerCLong;
2908 size_t cpu_map_valid_size =
2909 MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size);
2910
2911 cpu_to_node()->clear();
2912 cpu_to_node()->at_grow(cpu_num - 1);
2913
2914 size_t node_num = get_existing_num_nodes();
2915
2916 int distance = 0;
2917 int closest_distance = INT_MAX;
2918 int closest_node = 0;
2919 unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size, mtInternal);
2920 for (size_t i = 0; i < node_num; i++) {
2921 // Check if node is configured (not a memory-less node). If it is not, find
2922 // the closest configured node.
2923 if (!isnode_in_configured_nodes(nindex_to_node()->at(i))) {
2924 closest_distance = INT_MAX;
2925 // Check distance from all remaining nodes in the system. Ignore distance
2926 // from itself and from another non-configured node.
2927 for (size_t m = 0; m < node_num; m++) {
2928 if (m != i && isnode_in_configured_nodes(nindex_to_node()->at(m))) {
2929 distance = numa_distance(nindex_to_node()->at(i), nindex_to_node()->at(m));
2930 // If a closest node is found, update. There is always at least one
2931 // configured node in the system so there is always at least one node
2932 // close.
2933 if (distance != 0 && distance < closest_distance) {
2934 closest_distance = distance;
2935 closest_node = nindex_to_node()->at(m);
2936 }
2937 }
2938 }
2939 } else {
2940 // Current node is already a configured node.
2941 closest_node = nindex_to_node()->at(i);
2942 }
2943
2944 // Get cpus from the original node and map them to the closest node. If node
2945 // is a configured node (not a memory-less node), then original node and
2946 // closest node are the same.
2947 if (numa_node_to_cpus(nindex_to_node()->at(i), cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) {
2948 for (size_t j = 0; j < cpu_map_valid_size; j++) {
2949 if (cpu_map[j] != 0) {
2950 for (size_t k = 0; k < BitsPerCLong; k++) {
2951 if (cpu_map[j] & (1UL << k)) {
2952 cpu_to_node()->at_put(j * BitsPerCLong + k, closest_node);
2953 }
2954 }
2955 }
2956 }
2957 }
2958 }
2959 FREE_C_HEAP_ARRAY(unsigned long, cpu_map, mtInternal);
2960 }
2961
2962 int os::Linux::get_node_by_cpu(int cpu_id) {
2963 if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) {
2964 return cpu_to_node()->at(cpu_id);
2965 }
2966 return -1;
2967 }
2968
2969 GrowableArray<int>* os::Linux::_cpu_to_node;
2970 GrowableArray<int>* os::Linux::_nindex_to_node;
2971 os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu;
2972 os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus;
2973 os::Linux::numa_max_node_func_t os::Linux::_numa_max_node;
2974 os::Linux::numa_num_configured_nodes_func_t os::Linux::_numa_num_configured_nodes;
2975 os::Linux::numa_available_func_t os::Linux::_numa_available;
2976 os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory;
2977 os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory;
2978 os::Linux::numa_set_bind_policy_func_t os::Linux::_numa_set_bind_policy;
2979 os::Linux::numa_bitmask_isbitset_func_t os::Linux::_numa_bitmask_isbitset;
2980 os::Linux::numa_distance_func_t os::Linux::_numa_distance;
2981 unsigned long* os::Linux::_numa_all_nodes;
2982 struct bitmask* os::Linux::_numa_all_nodes_ptr;
2983 struct bitmask* os::Linux::_numa_nodes_ptr;
2984
2985 bool os::pd_uncommit_memory(char* addr, size_t size) {
2986 uintptr_t res = (uintptr_t) ::mmap(addr, size, PROT_NONE,
2987 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0);
2988 return res != (uintptr_t) MAP_FAILED;
2989 }
2990
2991 static
2992 address get_stack_commited_bottom(address bottom, size_t size) {
2993 address nbot = bottom;
2994 address ntop = bottom + size;
2995
2996 size_t page_sz = os::vm_page_size();
2997 unsigned pages = size / page_sz;
2998
2999 unsigned char vec[1];
3000 unsigned imin = 1, imax = pages + 1, imid;
3001 int mincore_return_value = 0;
3002
3003 assert(imin <= imax, "Unexpected page size");
3004
3005 while (imin < imax) {
3006 imid = (imax + imin) / 2;
3007 nbot = ntop - (imid * page_sz);
3008
3009 // Use a trick with mincore to check whether the page is mapped or not.
3010 // mincore sets vec to 1 if page resides in memory and to 0 if page
3011 // is swapped output but if page we are asking for is unmapped
3012 // it returns -1,ENOMEM
3013 mincore_return_value = mincore(nbot, page_sz, vec);
3014
3015 if (mincore_return_value == -1) {
3016 // Page is not mapped go up
3017 // to find first mapped page
3018 if (errno != EAGAIN) {
3019 assert(errno == ENOMEM, "Unexpected mincore errno");
3020 imax = imid;
3021 }
3022 } else {
3023 // Page is mapped go down
3024 // to find first not mapped page
3025 imin = imid + 1;
3026 }
3027 }
3028
3029 nbot = nbot + page_sz;
3030
3031 // Adjust stack bottom one page up if last checked page is not mapped
3032 if (mincore_return_value == -1) {
3033 nbot = nbot + page_sz;
3034 }
3035
3036 return nbot;
3037 }
3038
3039
3040 // Linux uses a growable mapping for the stack, and if the mapping for
3041 // the stack guard pages is not removed when we detach a thread the
3042 // stack cannot grow beyond the pages where the stack guard was
3043 // mapped. If at some point later in the process the stack expands to
3044 // that point, the Linux kernel cannot expand the stack any further
3045 // because the guard pages are in the way, and a segfault occurs.
3046 //
3047 // However, it's essential not to split the stack region by unmapping
3048 // a region (leaving a hole) that's already part of the stack mapping,
3049 // so if the stack mapping has already grown beyond the guard pages at
3050 // the time we create them, we have to truncate the stack mapping.
3051 // So, we need to know the extent of the stack mapping when
3052 // create_stack_guard_pages() is called.
3053
3054 // We only need this for stacks that are growable: at the time of
3055 // writing thread stacks don't use growable mappings (i.e. those
3056 // creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this
3057 // only applies to the main thread.
3058
3059 // If the (growable) stack mapping already extends beyond the point
3060 // where we're going to put our guard pages, truncate the mapping at
3061 // that point by munmap()ping it. This ensures that when we later
3062 // munmap() the guard pages we don't leave a hole in the stack
3063 // mapping. This only affects the main/initial thread
3064
3065 bool os::pd_create_stack_guard_pages(char* addr, size_t size) {
3066
3067 if (os::Linux::is_initial_thread()) {
3068 // As we manually grow stack up to bottom inside create_attached_thread(),
3069 // it's likely that os::Linux::initial_thread_stack_bottom is mapped and
3070 // we don't need to do anything special.
3071 // Check it first, before calling heavy function.
3072 uintptr_t stack_extent = (uintptr_t) os::Linux::initial_thread_stack_bottom();
3073 unsigned char vec[1];
3074
3075 if (mincore((address)stack_extent, os::vm_page_size(), vec) == -1) {
3076 // Fallback to slow path on all errors, including EAGAIN
3077 stack_extent = (uintptr_t) get_stack_commited_bottom(
3078 os::Linux::initial_thread_stack_bottom(),
3079 (size_t)addr - stack_extent);
3080 }
3081
3082 if (stack_extent < (uintptr_t)addr) {
3083 ::munmap((void*)stack_extent, (uintptr_t)(addr - stack_extent));
3084 }
3085 }
3086
3087 return os::commit_memory(addr, size, !ExecMem);
3088 }
3089
3090 // If this is a growable mapping, remove the guard pages entirely by
3091 // munmap()ping them. If not, just call uncommit_memory(). This only
3092 // affects the main/initial thread, but guard against future OS changes
3093 // It's safe to always unmap guard pages for initial thread because we
3094 // always place it right after end of the mapped region
3095
3096 bool os::remove_stack_guard_pages(char* addr, size_t size) {
3097 uintptr_t stack_extent, stack_base;
3098
3099 if (os::Linux::is_initial_thread()) {
3100 return ::munmap(addr, size) == 0;
3101 }
3102
3103 return os::uncommit_memory(addr, size);
3104 }
3105
3106 static address _highest_vm_reserved_address = NULL;
3107
3108 // If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory
3109 // at 'requested_addr'. If there are existing memory mappings at the same
3110 // location, however, they will be overwritten. If 'fixed' is false,
3111 // 'requested_addr' is only treated as a hint, the return value may or
3112 // may not start from the requested address. Unlike Linux mmap(), this
3113 // function returns NULL to indicate failure.
3114 static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) {
3115 char * addr;
3116 int flags;
3117
3118 flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS;
3119 if (fixed) {
3120 assert((uintptr_t)requested_addr % os::Linux::page_size() == 0, "unaligned address");
3121 flags |= MAP_FIXED;
3122 }
3123
3124 // Map reserved/uncommitted pages PROT_NONE so we fail early if we
3125 // touch an uncommitted page. Otherwise, the read/write might
3126 // succeed if we have enough swap space to back the physical page.
3127 addr = (char*)::mmap(requested_addr, bytes, PROT_NONE,
3128 flags, -1, 0);
3129
3130 if (addr != MAP_FAILED) {
3131 // anon_mmap() should only get called during VM initialization,
3132 // don't need lock (actually we can skip locking even it can be called
3133 // from multiple threads, because _highest_vm_reserved_address is just a
3134 // hint about the upper limit of non-stack memory regions.)
3135 if ((address)addr + bytes > _highest_vm_reserved_address) {
3136 _highest_vm_reserved_address = (address)addr + bytes;
3137 }
3138 }
3139
3140 return addr == MAP_FAILED ? NULL : addr;
3141 }
3142
3143 // Allocate (using mmap, NO_RESERVE, with small pages) at either a given request address
3144 // (req_addr != NULL) or with a given alignment.
3145 // - bytes shall be a multiple of alignment.
3146 // - req_addr can be NULL. If not NULL, it must be a multiple of alignment.
3147 // - alignment sets the alignment at which memory shall be allocated.
3148 // It must be a multiple of allocation granularity.
3149 // Returns address of memory or NULL. If req_addr was not NULL, will only return
3150 // req_addr or NULL.
3151 static char* anon_mmap_aligned(size_t bytes, size_t alignment, char* req_addr) {
3152
3153 size_t extra_size = bytes;
3154 if (req_addr == NULL && alignment > 0) {
3155 extra_size += alignment;
3156 }
3157
3158 char* start = (char*) ::mmap(req_addr, extra_size, PROT_NONE,
3159 MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE,
3160 -1, 0);
3161 if (start == MAP_FAILED) {
3162 start = NULL;
3163 } else {
3164 if (req_addr != NULL) {
3165 if (start != req_addr) {
3166 ::munmap(start, extra_size);
3167 start = NULL;
3168 }
3169 } else {
3170 char* const start_aligned = (char*) align_ptr_up(start, alignment);
3171 char* const end_aligned = start_aligned + bytes;
3172 char* const end = start + extra_size;
3173 if (start_aligned > start) {
3174 ::munmap(start, start_aligned - start);
3175 }
3176 if (end_aligned < end) {
3177 ::munmap(end_aligned, end - end_aligned);
3178 }
3179 start = start_aligned;
3180 }
3181 }
3182 return start;
3183 }
3184
3185 // Don't update _highest_vm_reserved_address, because there might be memory
3186 // regions above addr + size. If so, releasing a memory region only creates
3187 // a hole in the address space, it doesn't help prevent heap-stack collision.
3188 //
3189 static int anon_munmap(char * addr, size_t size) {
3190 return ::munmap(addr, size) == 0;
3191 }
3192
3193 char* os::pd_reserve_memory(size_t bytes, char* requested_addr,
3194 size_t alignment_hint) {
3195 return anon_mmap(requested_addr, bytes, (requested_addr != NULL));
3196 }
3197
3198 bool os::pd_release_memory(char* addr, size_t size) {
3199 return anon_munmap(addr, size);
3200 }
3201
3202 static address highest_vm_reserved_address() {
3203 return _highest_vm_reserved_address;
3204 }
3205
3206 static bool linux_mprotect(char* addr, size_t size, int prot) {
3207 // Linux wants the mprotect address argument to be page aligned.
3208 char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::page_size());
3209
3210 // According to SUSv3, mprotect() should only be used with mappings
3211 // established by mmap(), and mmap() always maps whole pages. Unaligned
3212 // 'addr' likely indicates problem in the VM (e.g. trying to change
3213 // protection of malloc'ed or statically allocated memory). Check the
3214 // caller if you hit this assert.
3215 assert(addr == bottom, "sanity check");
3216
3217 size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Linux::page_size());
3218 return ::mprotect(bottom, size, prot) == 0;
3219 }
3220
3221 // Set protections specified
3222 bool os::protect_memory(char* addr, size_t bytes, ProtType prot,
3223 bool is_committed) {
3224 unsigned int p = 0;
3225 switch (prot) {
3226 case MEM_PROT_NONE: p = PROT_NONE; break;
3227 case MEM_PROT_READ: p = PROT_READ; break;
3228 case MEM_PROT_RW: p = PROT_READ|PROT_WRITE; break;
3229 case MEM_PROT_RWX: p = PROT_READ|PROT_WRITE|PROT_EXEC; break;
3230 default:
3231 ShouldNotReachHere();
3232 }
3233 // is_committed is unused.
3234 return linux_mprotect(addr, bytes, p);
3235 }
3236
3237 bool os::guard_memory(char* addr, size_t size) {
3238 return linux_mprotect(addr, size, PROT_NONE);
3239 }
3240
3241 bool os::unguard_memory(char* addr, size_t size) {
3242 return linux_mprotect(addr, size, PROT_READ|PROT_WRITE);
3243 }
3244
3245 bool os::Linux::transparent_huge_pages_sanity_check(bool warn, size_t page_size) {
3246 bool result = false;
3247 void *p = mmap(NULL, page_size * 2, PROT_READ|PROT_WRITE,
3248 MAP_ANONYMOUS|MAP_PRIVATE,
3249 -1, 0);
3250 if (p != MAP_FAILED) {
3251 void *aligned_p = align_ptr_up(p, page_size);
3252
3253 result = madvise(aligned_p, page_size, MADV_HUGEPAGE) == 0;
3254
3255 munmap(p, page_size * 2);
3256 }
3257
3258 if (warn && !result) {
3259 warning("TransparentHugePages is not supported by the operating system.");
3260 }
3261
3262 return result;
3263 }
3264
3265 bool os::Linux::hugetlbfs_sanity_check(bool warn, size_t page_size) {
3266 bool result = false;
3267 void *p = mmap(NULL, page_size, PROT_READ|PROT_WRITE,
3268 MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB,
3269 -1, 0);
3270
3271 if (p != MAP_FAILED) {
3272 // We don't know if this really is a huge page or not.
3273 FILE *fp = fopen("/proc/self/maps", "r");
3274 if (fp) {
3275 while (!feof(fp)) {
3276 char chars[257];
3277 long x = 0;
3278 if (fgets(chars, sizeof(chars), fp)) {
3279 if (sscanf(chars, "%lx-%*x", &x) == 1
3280 && x == (long)p) {
3281 if (strstr (chars, "hugepage")) {
3282 result = true;
3283 break;
3284 }
3285 }
3286 }
3287 }
3288 fclose(fp);
3289 }
3290 munmap(p, page_size);
3291 }
3292
3293 if (warn && !result) {
3294 warning("HugeTLBFS is not supported by the operating system.");
3295 }
3296
3297 return result;
3298 }
3299
3300 /*
3301 * Set the coredump_filter bits to include largepages in core dump (bit 6)
3302 *
3303 * From the coredump_filter documentation:
3304 *
3305 * - (bit 0) anonymous private memory
3306 * - (bit 1) anonymous shared memory
3307 * - (bit 2) file-backed private memory
3308 * - (bit 3) file-backed shared memory
3309 * - (bit 4) ELF header pages in file-backed private memory areas (it is
3310 * effective only if the bit 2 is cleared)
3311 * - (bit 5) hugetlb private memory
3312 * - (bit 6) hugetlb shared memory
3313 */
3314 static void set_coredump_filter(void) {
3315 FILE *f;
3316 long cdm;
3317
3318 if ((f = fopen("/proc/self/coredump_filter", "r+")) == NULL) {
3319 return;
3320 }
3321
3322 if (fscanf(f, "%lx", &cdm) != 1) {
3323 fclose(f);
3324 return;
3325 }
3326
3327 rewind(f);
3328
3329 if ((cdm & LARGEPAGES_BIT) == 0) {
3330 cdm |= LARGEPAGES_BIT;
3331 fprintf(f, "%#lx", cdm);
3332 }
3333
3334 fclose(f);
3335 }
3336
3337 // Large page support
3338
3339 static size_t _large_page_size = 0;
3340
3341 size_t os::Linux::find_large_page_size() {
3342 size_t large_page_size = 0;
3343
3344 // large_page_size on Linux is used to round up heap size. x86 uses either
3345 // 2M or 4M page, depending on whether PAE (Physical Address Extensions)
3346 // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use
3347 // page as large as 256M.
3348 //
3349 // Here we try to figure out page size by parsing /proc/meminfo and looking
3350 // for a line with the following format:
3351 // Hugepagesize: 2048 kB
3352 //
3353 // If we can't determine the value (e.g. /proc is not mounted, or the text
3354 // format has been changed), we'll use the largest page size supported by
3355 // the processor.
3356
3357 #ifndef ZERO
3358 large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M)
3359 ARM_ONLY(2 * M) PPC_ONLY(4 * M);
3360 #endif // ZERO
3361
3362 FILE *fp = fopen("/proc/meminfo", "r");
3363 if (fp) {
3364 while (!feof(fp)) {
3365 int x = 0;
3366 char buf[16];
3367 if (fscanf(fp, "Hugepagesize: %d", &x) == 1) {
3368 if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) {
3369 large_page_size = x * K;
3370 break;
3371 }
3372 } else {
3373 // skip to next line
3374 for (;;) {
3375 int ch = fgetc(fp);
3376 if (ch == EOF || ch == (int)'\n') break;
3377 }
3378 }
3379 }
3380 fclose(fp);
3381 }
3382
3383 if (!FLAG_IS_DEFAULT(LargePageSizeInBytes) && LargePageSizeInBytes != large_page_size) {
3384 warning("Setting LargePageSizeInBytes has no effect on this OS. Large page size is "
3385 SIZE_FORMAT "%s.", byte_size_in_proper_unit(large_page_size),
3386 proper_unit_for_byte_size(large_page_size));
3387 }
3388
3389 return large_page_size;
3390 }
3391
3392 size_t os::Linux::setup_large_page_size() {
3393 _large_page_size = Linux::find_large_page_size();
3394 const size_t default_page_size = (size_t)Linux::page_size();
3395 if (_large_page_size > default_page_size) {
3396 _page_sizes[0] = _large_page_size;
3397 _page_sizes[1] = default_page_size;
3398 _page_sizes[2] = 0;
3399 }
3400
3401 return _large_page_size;
3402 }
3403
3404 bool os::Linux::setup_large_page_type(size_t page_size) {
3405 if (FLAG_IS_DEFAULT(UseHugeTLBFS) &&
3406 FLAG_IS_DEFAULT(UseSHM) &&
3407 FLAG_IS_DEFAULT(UseTransparentHugePages)) {
3408
3409 // The type of large pages has not been specified by the user.
3410
3411 // Try UseHugeTLBFS and then UseSHM.
3412 UseHugeTLBFS = UseSHM = true;
3413
3414 // Don't try UseTransparentHugePages since there are known
3415 // performance issues with it turned on. This might change in the future.
3416 UseTransparentHugePages = false;
3417 }
3418
3419 if (UseTransparentHugePages) {
3420 bool warn_on_failure = !FLAG_IS_DEFAULT(UseTransparentHugePages);
3421 if (transparent_huge_pages_sanity_check(warn_on_failure, page_size)) {
3422 UseHugeTLBFS = false;
3423 UseSHM = false;
3424 return true;
3425 }
3426 UseTransparentHugePages = false;
3427 }
3428
3429 if (UseHugeTLBFS) {
3430 bool warn_on_failure = !FLAG_IS_DEFAULT(UseHugeTLBFS);
3431 if (hugetlbfs_sanity_check(warn_on_failure, page_size)) {
3432 UseSHM = false;
3433 return true;
3434 }
3435 UseHugeTLBFS = false;
3436 }
3437
3438 return UseSHM;
3439 }
3440
3441 void os::large_page_init() {
3442 if (!UseLargePages &&
3443 !UseTransparentHugePages &&
3444 !UseHugeTLBFS &&
3445 !UseSHM) {
3446 // Not using large pages.
3447 return;
3448 }
3449
3450 if (!FLAG_IS_DEFAULT(UseLargePages) && !UseLargePages) {
3451 // The user explicitly turned off large pages.
3452 // Ignore the rest of the large pages flags.
3453 UseTransparentHugePages = false;
3454 UseHugeTLBFS = false;
3455 UseSHM = false;
3456 return;
3457 }
3458
3459 size_t large_page_size = Linux::setup_large_page_size();
3460 UseLargePages = Linux::setup_large_page_type(large_page_size);
3461
3462 set_coredump_filter();
3463 }
3464
3465 #ifndef SHM_HUGETLB
3466 #define SHM_HUGETLB 04000
3467 #endif
3468
3469 #define shm_warning_format(format, ...) \
3470 do { \
3471 if (UseLargePages && \
3472 (!FLAG_IS_DEFAULT(UseLargePages) || \
3473 !FLAG_IS_DEFAULT(UseSHM) || \
3474 !FLAG_IS_DEFAULT(LargePageSizeInBytes))) { \
3475 warning(format, __VA_ARGS__); \
3476 } \
3477 } while (0)
3478
3479 #define shm_warning(str) shm_warning_format("%s", str)
3480
3481 #define shm_warning_with_errno(str) \
3482 do { \
3483 int err = errno; \
3484 shm_warning_format(str " (error = %d)", err); \
3485 } while (0)
3486
3487 static char* shmat_with_alignment(int shmid, size_t bytes, size_t alignment) {
3488 assert(is_size_aligned(bytes, alignment), "Must be divisible by the alignment");
3489
3490 if (!is_size_aligned(alignment, SHMLBA)) {
3491 assert(false, "Code below assumes that alignment is at least SHMLBA aligned");
3492 return NULL;
3493 }
3494
3495 // To ensure that we get 'alignment' aligned memory from shmat,
3496 // we pre-reserve aligned virtual memory and then attach to that.
3497
3498 char* pre_reserved_addr = anon_mmap_aligned(bytes, alignment, NULL);
3499 if (pre_reserved_addr == NULL) {
3500 // Couldn't pre-reserve aligned memory.
3501 shm_warning("Failed to pre-reserve aligned memory for shmat.");
3502 return NULL;
3503 }
3504
3505 // SHM_REMAP is needed to allow shmat to map over an existing mapping.
3506 char* addr = (char*)shmat(shmid, pre_reserved_addr, SHM_REMAP);
3507
3508 if ((intptr_t)addr == -1) {
3509 int err = errno;
3510 shm_warning_with_errno("Failed to attach shared memory.");
3511
3512 assert(err != EACCES, "Unexpected error");
3513 assert(err != EIDRM, "Unexpected error");
3514 assert(err != EINVAL, "Unexpected error");
3515
3516 // Since we don't know if the kernel unmapped the pre-reserved memory area
3517 // we can't unmap it, since that would potentially unmap memory that was
3518 // mapped from other threads.
3519 return NULL;
3520 }
3521
3522 return addr;
3523 }
3524
3525 static char* shmat_at_address(int shmid, char* req_addr) {
3526 if (!is_ptr_aligned(req_addr, SHMLBA)) {
3527 assert(false, "Requested address needs to be SHMLBA aligned");
3528 return NULL;
3529 }
3530
3531 char* addr = (char*)shmat(shmid, req_addr, 0);
3532
3533 if ((intptr_t)addr == -1) {
3534 shm_warning_with_errno("Failed to attach shared memory.");
3535 return NULL;
3536 }
3537
3538 return addr;
3539 }
3540
3541 static char* shmat_large_pages(int shmid, size_t bytes, size_t alignment, char* req_addr) {
3542 // If a req_addr has been provided, we assume that the caller has already aligned the address.
3543 if (req_addr != NULL) {
3544 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Must be divisible by the large page size");
3545 assert(is_ptr_aligned(req_addr, alignment), "Must be divisible by given alignment");
3546 return shmat_at_address(shmid, req_addr);
3547 }
3548
3549 // Since shmid has been setup with SHM_HUGETLB, shmat will automatically
3550 // return large page size aligned memory addresses when req_addr == NULL.
3551 // However, if the alignment is larger than the large page size, we have
3552 // to manually ensure that the memory returned is 'alignment' aligned.
3553 if (alignment > os::large_page_size()) {
3554 assert(is_size_aligned(alignment, os::large_page_size()), "Must be divisible by the large page size");
3555 return shmat_with_alignment(shmid, bytes, alignment);
3556 } else {
3557 return shmat_at_address(shmid, NULL);
3558 }
3559 }
3560
3561 char* os::Linux::reserve_memory_special_shm(size_t bytes, size_t alignment, char* req_addr, bool exec) {
3562 // "exec" is passed in but not used. Creating the shared image for
3563 // the code cache doesn't have an SHM_X executable permission to check.
3564 assert(UseLargePages && UseSHM, "only for SHM large pages");
3565 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address");
3566 assert(is_ptr_aligned(req_addr, alignment), "Unaligned address");
3567
3568 if (!is_size_aligned(bytes, os::large_page_size())) {
3569 return NULL; // Fallback to small pages.
3570 }
3571
3572 // Create a large shared memory region to attach to based on size.
3573 // Currently, size is the total size of the heap.
3574 int shmid = shmget(IPC_PRIVATE, bytes, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W);
3575 if (shmid == -1) {
3576 // Possible reasons for shmget failure:
3577 // 1. shmmax is too small for Java heap.
3578 // > check shmmax value: cat /proc/sys/kernel/shmmax
3579 // > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax
3580 // 2. not enough large page memory.
3581 // > check available large pages: cat /proc/meminfo
3582 // > increase amount of large pages:
3583 // echo new_value > /proc/sys/vm/nr_hugepages
3584 // Note 1: different Linux may use different name for this property,
3585 // e.g. on Redhat AS-3 it is "hugetlb_pool".
3586 // Note 2: it's possible there's enough physical memory available but
3587 // they are so fragmented after a long run that they can't
3588 // coalesce into large pages. Try to reserve large pages when
3589 // the system is still "fresh".
3590 shm_warning_with_errno("Failed to reserve shared memory.");
3591 return NULL;
3592 }
3593
3594 // Attach to the region.
3595 char* addr = shmat_large_pages(shmid, bytes, alignment, req_addr);
3596
3597 // Remove shmid. If shmat() is successful, the actual shared memory segment
3598 // will be deleted when it's detached by shmdt() or when the process
3599 // terminates. If shmat() is not successful this will remove the shared
3600 // segment immediately.
3601 shmctl(shmid, IPC_RMID, NULL);
3602
3603 return addr;
3604 }
3605
3606 static void warn_on_large_pages_failure(char* req_addr, size_t bytes, int error) {
3607 assert(error == ENOMEM, "Only expect to fail if no memory is available");
3608
3609 bool warn_on_failure = UseLargePages &&
3610 (!FLAG_IS_DEFAULT(UseLargePages) ||
3611 !FLAG_IS_DEFAULT(UseHugeTLBFS) ||
3612 !FLAG_IS_DEFAULT(LargePageSizeInBytes));
3613
3614 if (warn_on_failure) {
3615 char msg[128];
3616 jio_snprintf(msg, sizeof(msg), "Failed to reserve large pages memory req_addr: "
3617 PTR_FORMAT " bytes: " SIZE_FORMAT " (errno = %d).", req_addr, bytes, error);
3618 warning("%s", msg);
3619 }
3620 }
3621
3622 char* os::Linux::reserve_memory_special_huge_tlbfs_only(size_t bytes, char* req_addr, bool exec) {
3623 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages");
3624 assert(is_size_aligned(bytes, os::large_page_size()), "Unaligned size");
3625 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address");
3626
3627 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
3628 char* addr = (char*)::mmap(req_addr, bytes, prot,
3629 MAP_PRIVATE|MAP_ANONYMOUS|MAP_HUGETLB,
3630 -1, 0);
3631
3632 if (addr == MAP_FAILED) {
3633 warn_on_large_pages_failure(req_addr, bytes, errno);
3634 return NULL;
3635 }
3636
3637 assert(is_ptr_aligned(addr, os::large_page_size()), "Must be");
3638
3639 return addr;
3640 }
3641
3642 // Reserve memory using mmap(MAP_HUGETLB).
3643 // - bytes shall be a multiple of alignment.
3644 // - req_addr can be NULL. If not NULL, it must be a multiple of alignment.
3645 // - alignment sets the alignment at which memory shall be allocated.
3646 // It must be a multiple of allocation granularity.
3647 // Returns address of memory or NULL. If req_addr was not NULL, will only return
3648 // req_addr or NULL.
3649 char* os::Linux::reserve_memory_special_huge_tlbfs_mixed(size_t bytes, size_t alignment, char* req_addr, bool exec) {
3650 size_t large_page_size = os::large_page_size();
3651 assert(bytes >= large_page_size, "Shouldn't allocate large pages for small sizes");
3652
3653 assert(is_ptr_aligned(req_addr, alignment), "Must be");
3654 assert(is_size_aligned(bytes, alignment), "Must be");
3655
3656 // First reserve - but not commit - the address range in small pages.
3657 char* const start = anon_mmap_aligned(bytes, alignment, req_addr);
3658
3659 if (start == NULL) {
3660 return NULL;
3661 }
3662
3663 assert(is_ptr_aligned(start, alignment), "Must be");
3664
3665 char* end = start + bytes;
3666
3667 // Find the regions of the allocated chunk that can be promoted to large pages.
3668 char* lp_start = (char*)align_ptr_up(start, large_page_size);
3669 char* lp_end = (char*)align_ptr_down(end, large_page_size);
3670
3671 size_t lp_bytes = lp_end - lp_start;
3672
3673 assert(is_size_aligned(lp_bytes, large_page_size), "Must be");
3674
3675 if (lp_bytes == 0) {
3676 // The mapped region doesn't even span the start and the end of a large page.
3677 // Fall back to allocate a non-special area.
3678 ::munmap(start, end - start);
3679 return NULL;
3680 }
3681
3682 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
3683
3684 void* result;
3685
3686 // Commit small-paged leading area.
3687 if (start != lp_start) {
3688 result = ::mmap(start, lp_start - start, prot,
3689 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED,
3690 -1, 0);
3691 if (result == MAP_FAILED) {
3692 ::munmap(lp_start, end - lp_start);
3693 return NULL;
3694 }
3695 }
3696
3697 // Commit large-paged area.
3698 result = ::mmap(lp_start, lp_bytes, prot,
3699 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED|MAP_HUGETLB,
3700 -1, 0);
3701 if (result == MAP_FAILED) {
3702 warn_on_large_pages_failure(lp_start, lp_bytes, errno);
3703 // If the mmap above fails, the large pages region will be unmapped and we
3704 // have regions before and after with small pages. Release these regions.
3705 //
3706 // | mapped | unmapped | mapped |
3707 // ^ ^ ^ ^
3708 // start lp_start lp_end end
3709 //
3710 ::munmap(start, lp_start - start);
3711 ::munmap(lp_end, end - lp_end);
3712 return NULL;
3713 }
3714
3715 // Commit small-paged trailing area.
3716 if (lp_end != end) {
3717 result = ::mmap(lp_end, end - lp_end, prot,
3718 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED,
3719 -1, 0);
3720 if (result == MAP_FAILED) {
3721 ::munmap(start, lp_end - start);
3722 return NULL;
3723 }
3724 }
3725
3726 return start;
3727 }
3728
3729 char* os::Linux::reserve_memory_special_huge_tlbfs(size_t bytes, size_t alignment, char* req_addr, bool exec) {
3730 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages");
3731 assert(is_ptr_aligned(req_addr, alignment), "Must be");
3732 assert(is_size_aligned(alignment, os::vm_allocation_granularity()), "Must be");
3733 assert(is_power_of_2(os::large_page_size()), "Must be");
3734 assert(bytes >= os::large_page_size(), "Shouldn't allocate large pages for small sizes");
3735
3736 if (is_size_aligned(bytes, os::large_page_size()) && alignment <= os::large_page_size()) {
3737 return reserve_memory_special_huge_tlbfs_only(bytes, req_addr, exec);
3738 } else {
3739 return reserve_memory_special_huge_tlbfs_mixed(bytes, alignment, req_addr, exec);
3740 }
3741 }
3742
3743 char* os::reserve_memory_special(size_t bytes, size_t alignment, char* req_addr, bool exec) {
3744 assert(UseLargePages, "only for large pages");
3745
3746 char* addr;
3747 if (UseSHM) {
3748 addr = os::Linux::reserve_memory_special_shm(bytes, alignment, req_addr, exec);
3749 } else {
3750 assert(UseHugeTLBFS, "must be");
3751 addr = os::Linux::reserve_memory_special_huge_tlbfs(bytes, alignment, req_addr, exec);
3752 }
3753
3754 if (addr != NULL) {
3755 if (UseNUMAInterleaving) {
3756 numa_make_global(addr, bytes);
3757 }
3758
3759 // The memory is committed
3760 MemTracker::record_virtual_memory_reserve_and_commit((address)addr, bytes, CALLER_PC);
3761 }
3762
3763 return addr;
3764 }
3765
3766 bool os::Linux::release_memory_special_shm(char* base, size_t bytes) {
3767 // detaching the SHM segment will also delete it, see reserve_memory_special_shm()
3768 return shmdt(base) == 0;
3769 }
3770
3771 bool os::Linux::release_memory_special_huge_tlbfs(char* base, size_t bytes) {
3772 return pd_release_memory(base, bytes);
3773 }
3774
3775 bool os::release_memory_special(char* base, size_t bytes) {
3776 bool res;
3777 if (MemTracker::tracking_level() > NMT_minimal) {
3778 Tracker tkr = MemTracker::get_virtual_memory_release_tracker();
3779 res = os::Linux::release_memory_special_impl(base, bytes);
3780 if (res) {
3781 tkr.record((address)base, bytes);
3782 }
3783
3784 } else {
3785 res = os::Linux::release_memory_special_impl(base, bytes);
3786 }
3787 return res;
3788 }
3789
3790 bool os::Linux::release_memory_special_impl(char* base, size_t bytes) {
3791 assert(UseLargePages, "only for large pages");
3792 bool res;
3793
3794 if (UseSHM) {
3795 res = os::Linux::release_memory_special_shm(base, bytes);
3796 } else {
3797 assert(UseHugeTLBFS, "must be");
3798 res = os::Linux::release_memory_special_huge_tlbfs(base, bytes);
3799 }
3800 return res;
3801 }
3802
3803 size_t os::large_page_size() {
3804 return _large_page_size;
3805 }
3806
3807 // With SysV SHM the entire memory region must be allocated as shared
3808 // memory.
3809 // HugeTLBFS allows application to commit large page memory on demand.
3810 // However, when committing memory with HugeTLBFS fails, the region
3811 // that was supposed to be committed will lose the old reservation
3812 // and allow other threads to steal that memory region. Because of this
3813 // behavior we can't commit HugeTLBFS memory.
3814 bool os::can_commit_large_page_memory() {
3815 return UseTransparentHugePages;
3816 }
3817
3818 bool os::can_execute_large_page_memory() {
3819 return UseTransparentHugePages || UseHugeTLBFS;
3820 }
3821
3822 // Reserve memory at an arbitrary address, only if that area is
3823 // available (and not reserved for something else).
3824
3825 char* os::pd_attempt_reserve_memory_at(size_t bytes, char* requested_addr) {
3826 const int max_tries = 10;
3827 char* base[max_tries];
3828 size_t size[max_tries];
3829 const size_t gap = 0x000000;
3830
3831 // Assert only that the size is a multiple of the page size, since
3832 // that's all that mmap requires, and since that's all we really know
3833 // about at this low abstraction level. If we need higher alignment,
3834 // we can either pass an alignment to this method or verify alignment
3835 // in one of the methods further up the call chain. See bug 5044738.
3836 assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block");
3837
3838 // Repeatedly allocate blocks until the block is allocated at the
3839 // right spot. Give up after max_tries. Note that reserve_memory() will
3840 // automatically update _highest_vm_reserved_address if the call is
3841 // successful. The variable tracks the highest memory address every reserved
3842 // by JVM. It is used to detect heap-stack collision if running with
3843 // fixed-stack LinuxThreads. Because here we may attempt to reserve more
3844 // space than needed, it could confuse the collision detecting code. To
3845 // solve the problem, save current _highest_vm_reserved_address and
3846 // calculate the correct value before return.
3847 address old_highest = _highest_vm_reserved_address;
3848
3849 // Linux mmap allows caller to pass an address as hint; give it a try first,
3850 // if kernel honors the hint then we can return immediately.
3851 char * addr = anon_mmap(requested_addr, bytes, false);
3852 if (addr == requested_addr) {
3853 return requested_addr;
3854 }
3855
3856 if (addr != NULL) {
3857 // mmap() is successful but it fails to reserve at the requested address
3858 anon_munmap(addr, bytes);
3859 }
3860
3861 int i;
3862 for (i = 0; i < max_tries; ++i) {
3863 base[i] = reserve_memory(bytes);
3864
3865 if (base[i] != NULL) {
3866 // Is this the block we wanted?
3867 if (base[i] == requested_addr) {
3868 size[i] = bytes;
3869 break;
3870 }
3871
3872 // Does this overlap the block we wanted? Give back the overlapped
3873 // parts and try again.
3874
3875 size_t top_overlap = requested_addr + (bytes + gap) - base[i];
3876 if (top_overlap >= 0 && top_overlap < bytes) {
3877 unmap_memory(base[i], top_overlap);
3878 base[i] += top_overlap;
3879 size[i] = bytes - top_overlap;
3880 } else {
3881 size_t bottom_overlap = base[i] + bytes - requested_addr;
3882 if (bottom_overlap >= 0 && bottom_overlap < bytes) {
3883 unmap_memory(requested_addr, bottom_overlap);
3884 size[i] = bytes - bottom_overlap;
3885 } else {
3886 size[i] = bytes;
3887 }
3888 }
3889 }
3890 }
3891
3892 // Give back the unused reserved pieces.
3893
3894 for (int j = 0; j < i; ++j) {
3895 if (base[j] != NULL) {
3896 unmap_memory(base[j], size[j]);
3897 }
3898 }
3899
3900 if (i < max_tries) {
3901 _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes);
3902 return requested_addr;
3903 } else {
3904 _highest_vm_reserved_address = old_highest;
3905 return NULL;
3906 }
3907 }
3908
3909 size_t os::read(int fd, void *buf, unsigned int nBytes) {
3910 return ::read(fd, buf, nBytes);
3911 }
3912
3913 // TODO-FIXME: reconcile Solaris' os::sleep with the linux variation.
3914 // Solaris uses poll(), linux uses park().
3915 // Poll() is likely a better choice, assuming that Thread.interrupt()
3916 // generates a SIGUSRx signal. Note that SIGUSR1 can interfere with
3917 // SIGSEGV, see 4355769.
3918
3919 int os::sleep(Thread* thread, jlong millis, bool interruptible) {
3920 assert(thread == Thread::current(), "thread consistency check");
3921
3922 ParkEvent * const slp = thread->_SleepEvent ;
3923 slp->reset() ;
3924 OrderAccess::fence() ;
3925
3926 if (interruptible) {
3927 jlong prevtime = javaTimeNanos();
3928
3929 for (;;) {
3930 if (os::is_interrupted(thread, true)) {
3931 return OS_INTRPT;
3932 }
3933
3934 jlong newtime = javaTimeNanos();
3935
3936 if (newtime - prevtime < 0) {
3937 // time moving backwards, should only happen if no monotonic clock
3938 // not a guarantee() because JVM should not abort on kernel/glibc bugs
3939 assert(!Linux::supports_monotonic_clock(), "time moving backwards");
3940 } else {
3941 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC;
3942 }
3943
3944 if(millis <= 0) {
3945 return OS_OK;
3946 }
3947
3948 prevtime = newtime;
3949
3950 {
3951 assert(thread->is_Java_thread(), "sanity check");
3952 JavaThread *jt = (JavaThread *) thread;
3953 ThreadBlockInVM tbivm(jt);
3954 OSThreadWaitState osts(jt->osthread(), false /* not Object.wait() */);
3955
3956 jt->set_suspend_equivalent();
3957 // cleared by handle_special_suspend_equivalent_condition() or
3958 // java_suspend_self() via check_and_wait_while_suspended()
3959
3960 slp->park(millis);
3961
3962 // were we externally suspended while we were waiting?
3963 jt->check_and_wait_while_suspended();
3964 }
3965 }
3966 } else {
3967 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */);
3968 jlong prevtime = javaTimeNanos();
3969
3970 for (;;) {
3971 // It'd be nice to avoid the back-to-back javaTimeNanos() calls on
3972 // the 1st iteration ...
3973 jlong newtime = javaTimeNanos();
3974
3975 if (newtime - prevtime < 0) {
3976 // time moving backwards, should only happen if no monotonic clock
3977 // not a guarantee() because JVM should not abort on kernel/glibc bugs
3978 assert(!Linux::supports_monotonic_clock(), "time moving backwards");
3979 } else {
3980 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC;
3981 }
3982
3983 if(millis <= 0) break ;
3984
3985 prevtime = newtime;
3986 slp->park(millis);
3987 }
3988 return OS_OK ;
3989 }
3990 }
3991
3992 //
3993 // Short sleep, direct OS call.
3994 //
3995 // Note: certain versions of Linux CFS scheduler (since 2.6.23) do not guarantee
3996 // sched_yield(2) will actually give up the CPU:
3997 //
3998 // * Alone on this pariticular CPU, keeps running.
3999 // * Before the introduction of "skip_buddy" with "compat_yield" disabled
4000 // (pre 2.6.39).
4001 //
4002 // So calling this with 0 is an alternative.
4003 //
4004 void os::naked_short_sleep(jlong ms) {
4005 struct timespec req;
4006
4007 assert(ms < 1000, "Un-interruptable sleep, short time use only");
4008 req.tv_sec = 0;
4009 if (ms > 0) {
4010 req.tv_nsec = (ms % 1000) * 1000000;
4011 }
4012 else {
4013 req.tv_nsec = 1;
4014 }
4015
4016 nanosleep(&req, NULL);
4017
4018 return;
4019 }
4020
4021 // Sleep forever; naked call to OS-specific sleep; use with CAUTION
4022 void os::infinite_sleep() {
4023 while (true) { // sleep forever ...
4024 ::sleep(100); // ... 100 seconds at a time
4025 }
4026 }
4027
4028 // Used to convert frequent JVM_Yield() to nops
4029 bool os::dont_yield() {
4030 return DontYieldALot;
4031 }
4032
4033 void os::yield() {
4034 sched_yield();
4035 }
4036
4037 os::YieldResult os::NakedYield() { sched_yield(); return os::YIELD_UNKNOWN ;}
4038
4039 void os::yield_all(int attempts) {
4040 // Yields to all threads, including threads with lower priorities
4041 // Threads on Linux are all with same priority. The Solaris style
4042 // os::yield_all() with nanosleep(1ms) is not necessary.
4043 sched_yield();
4044 }
4045
4046 // Called from the tight loops to possibly influence time-sharing heuristics
4047 void os::loop_breaker(int attempts) {
4048 os::yield_all(attempts);
4049 }
4050
4051 ////////////////////////////////////////////////////////////////////////////////
4052 // thread priority support
4053
4054 // Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER
4055 // only supports dynamic priority, static priority must be zero. For real-time
4056 // applications, Linux supports SCHED_RR which allows static priority (1-99).
4057 // However, for large multi-threaded applications, SCHED_RR is not only slower
4058 // than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out
4059 // of 5 runs - Sep 2005).
4060 //
4061 // The following code actually changes the niceness of kernel-thread/LWP. It
4062 // has an assumption that setpriority() only modifies one kernel-thread/LWP,
4063 // not the entire user process, and user level threads are 1:1 mapped to kernel
4064 // threads. It has always been the case, but could change in the future. For
4065 // this reason, the code should not be used as default (ThreadPriorityPolicy=0).
4066 // It is only used when ThreadPriorityPolicy=1 and requires root privilege.
4067
4068 int os::java_to_os_priority[CriticalPriority + 1] = {
4069 19, // 0 Entry should never be used
4070
4071 4, // 1 MinPriority
4072 3, // 2
4073 2, // 3
4074
4075 1, // 4
4076 0, // 5 NormPriority
4077 -1, // 6
4078
4079 -2, // 7
4080 -3, // 8
4081 -4, // 9 NearMaxPriority
4082
4083 -5, // 10 MaxPriority
4084
4085 -5 // 11 CriticalPriority
4086 };
4087
4088 static int prio_init() {
4089 if (ThreadPriorityPolicy == 1) {
4090 // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1
4091 // if effective uid is not root. Perhaps, a more elegant way of doing
4092 // this is to test CAP_SYS_NICE capability, but that will require libcap.so
4093 if (geteuid() != 0) {
4094 if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) {
4095 warning("-XX:ThreadPriorityPolicy requires root privilege on Linux");
4096 }
4097 ThreadPriorityPolicy = 0;
4098 }
4099 }
4100 if (UseCriticalJavaThreadPriority) {
4101 os::java_to_os_priority[MaxPriority] = os::java_to_os_priority[CriticalPriority];
4102 }
4103 return 0;
4104 }
4105
4106 OSReturn os::set_native_priority(Thread* thread, int newpri) {
4107 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) return OS_OK;
4108
4109 int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri);
4110 return (ret == 0) ? OS_OK : OS_ERR;
4111 }
4112
4113 OSReturn os::get_native_priority(const Thread* const thread, int *priority_ptr) {
4114 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) {
4115 *priority_ptr = java_to_os_priority[NormPriority];
4116 return OS_OK;
4117 }
4118
4119 errno = 0;
4120 *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id());
4121 return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR);
4122 }
4123
4124 // Hint to the underlying OS that a task switch would not be good.
4125 // Void return because it's a hint and can fail.
4126 void os::hint_no_preempt() {}
4127
4128 ////////////////////////////////////////////////////////////////////////////////
4129 // suspend/resume support
4130
4131 // the low-level signal-based suspend/resume support is a remnant from the
4132 // old VM-suspension that used to be for java-suspension, safepoints etc,
4133 // within hotspot. Now there is a single use-case for this:
4134 // - calling get_thread_pc() on the VMThread by the flat-profiler task
4135 // that runs in the watcher thread.
4136 // The remaining code is greatly simplified from the more general suspension
4137 // code that used to be used.
4138 //
4139 // The protocol is quite simple:
4140 // - suspend:
4141 // - sends a signal to the target thread
4142 // - polls the suspend state of the osthread using a yield loop
4143 // - target thread signal handler (SR_handler) sets suspend state
4144 // and blocks in sigsuspend until continued
4145 // - resume:
4146 // - sets target osthread state to continue
4147 // - sends signal to end the sigsuspend loop in the SR_handler
4148 //
4149 // Note that the SR_lock plays no role in this suspend/resume protocol.
4150 //
4151
4152 static void resume_clear_context(OSThread *osthread) {
4153 osthread->set_ucontext(NULL);
4154 osthread->set_siginfo(NULL);
4155 }
4156
4157 static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo, ucontext_t* context) {
4158 osthread->set_ucontext(context);
4159 osthread->set_siginfo(siginfo);
4160 }
4161
4162 //
4163 // Handler function invoked when a thread's execution is suspended or
4164 // resumed. We have to be careful that only async-safe functions are
4165 // called here (Note: most pthread functions are not async safe and
4166 // should be avoided.)
4167 //
4168 // Note: sigwait() is a more natural fit than sigsuspend() from an
4169 // interface point of view, but sigwait() prevents the signal hander
4170 // from being run. libpthread would get very confused by not having
4171 // its signal handlers run and prevents sigwait()'s use with the
4172 // mutex granting granting signal.
4173 //
4174 // Currently only ever called on the VMThread and JavaThreads (PC sampling)
4175 //
4176 static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) {
4177 // Save and restore errno to avoid confusing native code with EINTR
4178 // after sigsuspend.
4179 int old_errno = errno;
4180
4181 Thread* thread = Thread::current();
4182 OSThread* osthread = thread->osthread();
4183 assert(thread->is_VM_thread() || thread->is_Java_thread(), "Must be VMThread or JavaThread");
4184
4185 os::SuspendResume::State current = osthread->sr.state();
4186 if (current == os::SuspendResume::SR_SUSPEND_REQUEST) {
4187 suspend_save_context(osthread, siginfo, context);
4188
4189 // attempt to switch the state, we assume we had a SUSPEND_REQUEST
4190 os::SuspendResume::State state = osthread->sr.suspended();
4191 if (state == os::SuspendResume::SR_SUSPENDED) {
4192 sigset_t suspend_set; // signals for sigsuspend()
4193
4194 // get current set of blocked signals and unblock resume signal
4195 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set);
4196 sigdelset(&suspend_set, SR_signum);
4197
4198 sr_semaphore.signal();
4199 // wait here until we are resumed
4200 while (1) {
4201 sigsuspend(&suspend_set);
4202
4203 os::SuspendResume::State result = osthread->sr.running();
4204 if (result == os::SuspendResume::SR_RUNNING) {
4205 sr_semaphore.signal();
4206 break;
4207 }
4208 }
4209
4210 } else if (state == os::SuspendResume::SR_RUNNING) {
4211 // request was cancelled, continue
4212 } else {
4213 ShouldNotReachHere();
4214 }
4215
4216 resume_clear_context(osthread);
4217 } else if (current == os::SuspendResume::SR_RUNNING) {
4218 // request was cancelled, continue
4219 } else if (current == os::SuspendResume::SR_WAKEUP_REQUEST) {
4220 // ignore
4221 } else {
4222 // ignore
4223 }
4224
4225 errno = old_errno;
4226 }
4227
4228
4229 static int SR_initialize() {
4230 struct sigaction act;
4231 char *s;
4232 /* Get signal number to use for suspend/resume */
4233 if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) {
4234 int sig = ::strtol(s, 0, 10);
4235 if (sig > 0 || sig < _NSIG) {
4236 SR_signum = sig;
4237 }
4238 }
4239
4240 assert(SR_signum > SIGSEGV && SR_signum > SIGBUS,
4241 "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769");
4242
4243 sigemptyset(&SR_sigset);
4244 sigaddset(&SR_sigset, SR_signum);
4245
4246 /* Set up signal handler for suspend/resume */
4247 act.sa_flags = SA_RESTART|SA_SIGINFO;
4248 act.sa_handler = (void (*)(int)) SR_handler;
4249
4250 // SR_signum is blocked by default.
4251 // 4528190 - We also need to block pthread restart signal (32 on all
4252 // supported Linux platforms). Note that LinuxThreads need to block
4253 // this signal for all threads to work properly. So we don't have
4254 // to use hard-coded signal number when setting up the mask.
4255 pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask);
4256
4257 if (sigaction(SR_signum, &act, 0) == -1) {
4258 return -1;
4259 }
4260
4261 // Save signal flag
4262 os::Linux::set_our_sigflags(SR_signum, act.sa_flags);
4263 return 0;
4264 }
4265
4266 static int sr_notify(OSThread* osthread) {
4267 int status = pthread_kill(osthread->pthread_id(), SR_signum);
4268 assert_status(status == 0, status, "pthread_kill");
4269 return status;
4270 }
4271
4272 // "Randomly" selected value for how long we want to spin
4273 // before bailing out on suspending a thread, also how often
4274 // we send a signal to a thread we want to resume
4275 static const int RANDOMLY_LARGE_INTEGER = 1000000;
4276 static const int RANDOMLY_LARGE_INTEGER2 = 100;
4277
4278 // returns true on success and false on error - really an error is fatal
4279 // but this seems the normal response to library errors
4280 static bool do_suspend(OSThread* osthread) {
4281 assert(osthread->sr.is_running(), "thread should be running");
4282 assert(!sr_semaphore.trywait(), "semaphore has invalid state");
4283
4284 // mark as suspended and send signal
4285 if (osthread->sr.request_suspend() != os::SuspendResume::SR_SUSPEND_REQUEST) {
4286 // failed to switch, state wasn't running?
4287 ShouldNotReachHere();
4288 return false;
4289 }
4290
4291 if (sr_notify(osthread) != 0) {
4292 ShouldNotReachHere();
4293 }
4294
4295 // managed to send the signal and switch to SUSPEND_REQUEST, now wait for SUSPENDED
4296 while (true) {
4297 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) {
4298 break;
4299 } else {
4300 // timeout
4301 os::SuspendResume::State cancelled = osthread->sr.cancel_suspend();
4302 if (cancelled == os::SuspendResume::SR_RUNNING) {
4303 return false;
4304 } else if (cancelled == os::SuspendResume::SR_SUSPENDED) {
4305 // make sure that we consume the signal on the semaphore as well
4306 sr_semaphore.wait();
4307 break;
4308 } else {
4309 ShouldNotReachHere();
4310 return false;
4311 }
4312 }
4313 }
4314
4315 guarantee(osthread->sr.is_suspended(), "Must be suspended");
4316 return true;
4317 }
4318
4319 static void do_resume(OSThread* osthread) {
4320 assert(osthread->sr.is_suspended(), "thread should be suspended");
4321 assert(!sr_semaphore.trywait(), "invalid semaphore state");
4322
4323 if (osthread->sr.request_wakeup() != os::SuspendResume::SR_WAKEUP_REQUEST) {
4324 // failed to switch to WAKEUP_REQUEST
4325 ShouldNotReachHere();
4326 return;
4327 }
4328
4329 while (true) {
4330 if (sr_notify(osthread) == 0) {
4331 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) {
4332 if (osthread->sr.is_running()) {
4333 return;
4334 }
4335 }
4336 } else {
4337 ShouldNotReachHere();
4338 }
4339 }
4340
4341 guarantee(osthread->sr.is_running(), "Must be running!");
4342 }
4343
4344 ////////////////////////////////////////////////////////////////////////////////
4345 // interrupt support
4346
4347 void os::interrupt(Thread* thread) {
4348 assert(Thread::current() == thread || Threads_lock->owned_by_self(),
4349 "possibility of dangling Thread pointer");
4350
4351 OSThread* osthread = thread->osthread();
4352
4353 if (!osthread->interrupted()) {
4354 osthread->set_interrupted(true);
4355 // More than one thread can get here with the same value of osthread,
4356 // resulting in multiple notifications. We do, however, want the store
4357 // to interrupted() to be visible to other threads before we execute unpark().
4358 OrderAccess::fence();
4359 ParkEvent * const slp = thread->_SleepEvent ;
4360 if (slp != NULL) slp->unpark() ;
4361 }
4362
4363 // For JSR166. Unpark even if interrupt status already was set
4364 if (thread->is_Java_thread())
4365 ((JavaThread*)thread)->parker()->unpark();
4366
4367 ParkEvent * ev = thread->_ParkEvent ;
4368 if (ev != NULL) ev->unpark() ;
4369
4370 }
4371
4372 bool os::is_interrupted(Thread* thread, bool clear_interrupted) {
4373 assert(Thread::current() == thread || Threads_lock->owned_by_self(),
4374 "possibility of dangling Thread pointer");
4375
4376 OSThread* osthread = thread->osthread();
4377
4378 bool interrupted = osthread->interrupted();
4379
4380 if (interrupted && clear_interrupted) {
4381 osthread->set_interrupted(false);
4382 // consider thread->_SleepEvent->reset() ... optional optimization
4383 }
4384
4385 return interrupted;
4386 }
4387
4388 ///////////////////////////////////////////////////////////////////////////////////
4389 // signal handling (except suspend/resume)
4390
4391 // This routine may be used by user applications as a "hook" to catch signals.
4392 // The user-defined signal handler must pass unrecognized signals to this
4393 // routine, and if it returns true (non-zero), then the signal handler must
4394 // return immediately. If the flag "abort_if_unrecognized" is true, then this
4395 // routine will never retun false (zero), but instead will execute a VM panic
4396 // routine kill the process.
4397 //
4398 // If this routine returns false, it is OK to call it again. This allows
4399 // the user-defined signal handler to perform checks either before or after
4400 // the VM performs its own checks. Naturally, the user code would be making
4401 // a serious error if it tried to handle an exception (such as a null check
4402 // or breakpoint) that the VM was generating for its own correct operation.
4403 //
4404 // This routine may recognize any of the following kinds of signals:
4405 // SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1.
4406 // It should be consulted by handlers for any of those signals.
4407 //
4408 // The caller of this routine must pass in the three arguments supplied
4409 // to the function referred to in the "sa_sigaction" (not the "sa_handler")
4410 // field of the structure passed to sigaction(). This routine assumes that
4411 // the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART.
4412 //
4413 // Note that the VM will print warnings if it detects conflicting signal
4414 // handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers".
4415 //
4416 extern "C" JNIEXPORT int
4417 JVM_handle_linux_signal(int signo, siginfo_t* siginfo,
4418 void* ucontext, int abort_if_unrecognized);
4419
4420 void signalHandler(int sig, siginfo_t* info, void* uc) {
4421 assert(info != NULL && uc != NULL, "it must be old kernel");
4422 int orig_errno = errno; // Preserve errno value over signal handler.
4423 JVM_handle_linux_signal(sig, info, uc, true);
4424 errno = orig_errno;
4425 }
4426
4427
4428 // This boolean allows users to forward their own non-matching signals
4429 // to JVM_handle_linux_signal, harmlessly.
4430 bool os::Linux::signal_handlers_are_installed = false;
4431
4432 // For signal-chaining
4433 struct sigaction os::Linux::sigact[MAXSIGNUM];
4434 unsigned int os::Linux::sigs = 0;
4435 bool os::Linux::libjsig_is_loaded = false;
4436 typedef struct sigaction *(*get_signal_t)(int);
4437 get_signal_t os::Linux::get_signal_action = NULL;
4438
4439 struct sigaction* os::Linux::get_chained_signal_action(int sig) {
4440 struct sigaction *actp = NULL;
4441
4442 if (libjsig_is_loaded) {
4443 // Retrieve the old signal handler from libjsig
4444 actp = (*get_signal_action)(sig);
4445 }
4446 if (actp == NULL) {
4447 // Retrieve the preinstalled signal handler from jvm
4448 actp = get_preinstalled_handler(sig);
4449 }
4450
4451 return actp;
4452 }
4453
4454 static bool call_chained_handler(struct sigaction *actp, int sig,
4455 siginfo_t *siginfo, void *context) {
4456 // Call the old signal handler
4457 if (actp->sa_handler == SIG_DFL) {
4458 // It's more reasonable to let jvm treat it as an unexpected exception
4459 // instead of taking the default action.
4460 return false;
4461 } else if (actp->sa_handler != SIG_IGN) {
4462 if ((actp->sa_flags & SA_NODEFER) == 0) {
4463 // automaticlly block the signal
4464 sigaddset(&(actp->sa_mask), sig);
4465 }
4466
4467 sa_handler_t hand = NULL;
4468 sa_sigaction_t sa = NULL;
4469 bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0;
4470 // retrieve the chained handler
4471 if (siginfo_flag_set) {
4472 sa = actp->sa_sigaction;
4473 } else {
4474 hand = actp->sa_handler;
4475 }
4476
4477 if ((actp->sa_flags & SA_RESETHAND) != 0) {
4478 actp->sa_handler = SIG_DFL;
4479 }
4480
4481 // try to honor the signal mask
4482 sigset_t oset;
4483 pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset);
4484
4485 // call into the chained handler
4486 if (siginfo_flag_set) {
4487 (*sa)(sig, siginfo, context);
4488 } else {
4489 (*hand)(sig);
4490 }
4491
4492 // restore the signal mask
4493 pthread_sigmask(SIG_SETMASK, &oset, 0);
4494 }
4495 // Tell jvm's signal handler the signal is taken care of.
4496 return true;
4497 }
4498
4499 bool os::Linux::chained_handler(int sig, siginfo_t* siginfo, void* context) {
4500 bool chained = false;
4501 // signal-chaining
4502 if (UseSignalChaining) {
4503 struct sigaction *actp = get_chained_signal_action(sig);
4504 if (actp != NULL) {
4505 chained = call_chained_handler(actp, sig, siginfo, context);
4506 }
4507 }
4508 return chained;
4509 }
4510
4511 struct sigaction* os::Linux::get_preinstalled_handler(int sig) {
4512 if ((( (unsigned int)1 << sig ) & sigs) != 0) {
4513 return &sigact[sig];
4514 }
4515 return NULL;
4516 }
4517
4518 void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) {
4519 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4520 sigact[sig] = oldAct;
4521 sigs |= (unsigned int)1 << sig;
4522 }
4523
4524 // for diagnostic
4525 int os::Linux::sigflags[MAXSIGNUM];
4526
4527 int os::Linux::get_our_sigflags(int sig) {
4528 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4529 return sigflags[sig];
4530 }
4531
4532 void os::Linux::set_our_sigflags(int sig, int flags) {
4533 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4534 sigflags[sig] = flags;
4535 }
4536
4537 void os::Linux::set_signal_handler(int sig, bool set_installed) {
4538 // Check for overwrite.
4539 struct sigaction oldAct;
4540 sigaction(sig, (struct sigaction*)NULL, &oldAct);
4541
4542 void* oldhand = oldAct.sa_sigaction
4543 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction)
4544 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler);
4545 if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) &&
4546 oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) &&
4547 oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) {
4548 if (AllowUserSignalHandlers || !set_installed) {
4549 // Do not overwrite; user takes responsibility to forward to us.
4550 return;
4551 } else if (UseSignalChaining) {
4552 // save the old handler in jvm
4553 save_preinstalled_handler(sig, oldAct);
4554 // libjsig also interposes the sigaction() call below and saves the
4555 // old sigaction on it own.
4556 } else {
4557 fatal(err_msg("Encountered unexpected pre-existing sigaction handler "
4558 "%#lx for signal %d.", (long)oldhand, sig));
4559 }
4560 }
4561
4562 struct sigaction sigAct;
4563 sigfillset(&(sigAct.sa_mask));
4564 sigAct.sa_handler = SIG_DFL;
4565 if (!set_installed) {
4566 sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
4567 } else {
4568 sigAct.sa_sigaction = signalHandler;
4569 sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
4570 }
4571 // Save flags, which are set by ours
4572 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4573 sigflags[sig] = sigAct.sa_flags;
4574
4575 int ret = sigaction(sig, &sigAct, &oldAct);
4576 assert(ret == 0, "check");
4577
4578 void* oldhand2 = oldAct.sa_sigaction
4579 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction)
4580 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler);
4581 assert(oldhand2 == oldhand, "no concurrent signal handler installation");
4582 }
4583
4584 // install signal handlers for signals that HotSpot needs to
4585 // handle in order to support Java-level exception handling.
4586
4587 void os::Linux::install_signal_handlers() {
4588 if (!signal_handlers_are_installed) {
4589 signal_handlers_are_installed = true;
4590
4591 // signal-chaining
4592 typedef void (*signal_setting_t)();
4593 signal_setting_t begin_signal_setting = NULL;
4594 signal_setting_t end_signal_setting = NULL;
4595 begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
4596 dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting"));
4597 if (begin_signal_setting != NULL) {
4598 end_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
4599 dlsym(RTLD_DEFAULT, "JVM_end_signal_setting"));
4600 get_signal_action = CAST_TO_FN_PTR(get_signal_t,
4601 dlsym(RTLD_DEFAULT, "JVM_get_signal_action"));
4602 libjsig_is_loaded = true;
4603 assert(UseSignalChaining, "should enable signal-chaining");
4604 }
4605 if (libjsig_is_loaded) {
4606 // Tell libjsig jvm is setting signal handlers
4607 (*begin_signal_setting)();
4608 }
4609
4610 set_signal_handler(SIGSEGV, true);
4611 set_signal_handler(SIGPIPE, true);
4612 set_signal_handler(SIGBUS, true);
4613 set_signal_handler(SIGILL, true);
4614 set_signal_handler(SIGFPE, true);
4615 #if defined(PPC64)
4616 set_signal_handler(SIGTRAP, true);
4617 #endif
4618 set_signal_handler(SIGXFSZ, true);
4619
4620 if (libjsig_is_loaded) {
4621 // Tell libjsig jvm finishes setting signal handlers
4622 (*end_signal_setting)();
4623 }
4624
4625 // We don't activate signal checker if libjsig is in place, we trust ourselves
4626 // and if UserSignalHandler is installed all bets are off.
4627 // Log that signal checking is off only if -verbose:jni is specified.
4628 if (CheckJNICalls) {
4629 if (libjsig_is_loaded) {
4630 if (PrintJNIResolving) {
4631 tty->print_cr("Info: libjsig is activated, all active signal checking is disabled");
4632 }
4633 check_signals = false;
4634 }
4635 if (AllowUserSignalHandlers) {
4636 if (PrintJNIResolving) {
4637 tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled");
4638 }
4639 check_signals = false;
4640 }
4641 }
4642 }
4643 }
4644
4645 // This is the fastest way to get thread cpu time on Linux.
4646 // Returns cpu time (user+sys) for any thread, not only for current.
4647 // POSIX compliant clocks are implemented in the kernels 2.6.16+.
4648 // It might work on 2.6.10+ with a special kernel/glibc patch.
4649 // For reference, please, see IEEE Std 1003.1-2004:
4650 // http://www.unix.org/single_unix_specification
4651
4652 jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) {
4653 struct timespec tp;
4654 int rc = os::Linux::clock_gettime(clockid, &tp);
4655 assert(rc == 0, "clock_gettime is expected to return 0 code");
4656
4657 return (tp.tv_sec * NANOSECS_PER_SEC) + tp.tv_nsec;
4658 }
4659
4660 /////
4661 // glibc on Linux platform uses non-documented flag
4662 // to indicate, that some special sort of signal
4663 // trampoline is used.
4664 // We will never set this flag, and we should
4665 // ignore this flag in our diagnostic
4666 #ifdef SIGNIFICANT_SIGNAL_MASK
4667 #undef SIGNIFICANT_SIGNAL_MASK
4668 #endif
4669 #define SIGNIFICANT_SIGNAL_MASK (~0x04000000)
4670
4671 static const char* get_signal_handler_name(address handler,
4672 char* buf, int buflen) {
4673 int offset = 0;
4674 bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset);
4675 if (found) {
4676 // skip directory names
4677 const char *p1, *p2;
4678 p1 = buf;
4679 size_t len = strlen(os::file_separator());
4680 while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len;
4681 jio_snprintf(buf, buflen, "%s+0x%x", p1, offset);
4682 } else {
4683 jio_snprintf(buf, buflen, PTR_FORMAT, handler);
4684 }
4685 return buf;
4686 }
4687
4688 static void print_signal_handler(outputStream* st, int sig,
4689 char* buf, size_t buflen) {
4690 struct sigaction sa;
4691
4692 sigaction(sig, NULL, &sa);
4693
4694 // See comment for SIGNIFICANT_SIGNAL_MASK define
4695 sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
4696
4697 st->print("%s: ", os::exception_name(sig, buf, buflen));
4698
4699 address handler = (sa.sa_flags & SA_SIGINFO)
4700 ? CAST_FROM_FN_PTR(address, sa.sa_sigaction)
4701 : CAST_FROM_FN_PTR(address, sa.sa_handler);
4702
4703 if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) {
4704 st->print("SIG_DFL");
4705 } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) {
4706 st->print("SIG_IGN");
4707 } else {
4708 st->print("[%s]", get_signal_handler_name(handler, buf, buflen));
4709 }
4710
4711 st->print(", sa_mask[0]=");
4712 os::Posix::print_signal_set_short(st, &sa.sa_mask);
4713
4714 address rh = VMError::get_resetted_sighandler(sig);
4715 // May be, handler was resetted by VMError?
4716 if(rh != NULL) {
4717 handler = rh;
4718 sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK;
4719 }
4720
4721 st->print(", sa_flags=");
4722 os::Posix::print_sa_flags(st, sa.sa_flags);
4723
4724 // Check: is it our handler?
4725 if(handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) ||
4726 handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) {
4727 // It is our signal handler
4728 // check for flags, reset system-used one!
4729 if((int)sa.sa_flags != os::Linux::get_our_sigflags(sig)) {
4730 st->print(
4731 ", flags was changed from " PTR32_FORMAT ", consider using jsig library",
4732 os::Linux::get_our_sigflags(sig));
4733 }
4734 }
4735 st->cr();
4736 }
4737
4738
4739 #define DO_SIGNAL_CHECK(sig) \
4740 if (!sigismember(&check_signal_done, sig)) \
4741 os::Linux::check_signal_handler(sig)
4742
4743 // This method is a periodic task to check for misbehaving JNI applications
4744 // under CheckJNI, we can add any periodic checks here
4745
4746 void os::run_periodic_checks() {
4747
4748 if (check_signals == false) return;
4749
4750 // SEGV and BUS if overridden could potentially prevent
4751 // generation of hs*.log in the event of a crash, debugging
4752 // such a case can be very challenging, so we absolutely
4753 // check the following for a good measure:
4754 DO_SIGNAL_CHECK(SIGSEGV);
4755 DO_SIGNAL_CHECK(SIGILL);
4756 DO_SIGNAL_CHECK(SIGFPE);
4757 DO_SIGNAL_CHECK(SIGBUS);
4758 DO_SIGNAL_CHECK(SIGPIPE);
4759 DO_SIGNAL_CHECK(SIGXFSZ);
4760 #if defined(PPC64)
4761 DO_SIGNAL_CHECK(SIGTRAP);
4762 #endif
4763
4764 // ReduceSignalUsage allows the user to override these handlers
4765 // see comments at the very top and jvm_solaris.h
4766 if (!ReduceSignalUsage) {
4767 DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL);
4768 DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL);
4769 DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL);
4770 DO_SIGNAL_CHECK(BREAK_SIGNAL);
4771 }
4772
4773 DO_SIGNAL_CHECK(SR_signum);
4774 DO_SIGNAL_CHECK(INTERRUPT_SIGNAL);
4775 }
4776
4777 typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *);
4778
4779 static os_sigaction_t os_sigaction = NULL;
4780
4781 void os::Linux::check_signal_handler(int sig) {
4782 char buf[O_BUFLEN];
4783 address jvmHandler = NULL;
4784
4785
4786 struct sigaction act;
4787 if (os_sigaction == NULL) {
4788 // only trust the default sigaction, in case it has been interposed
4789 os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction");
4790 if (os_sigaction == NULL) return;
4791 }
4792
4793 os_sigaction(sig, (struct sigaction*)NULL, &act);
4794
4795
4796 act.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
4797
4798 address thisHandler = (act.sa_flags & SA_SIGINFO)
4799 ? CAST_FROM_FN_PTR(address, act.sa_sigaction)
4800 : CAST_FROM_FN_PTR(address, act.sa_handler) ;
4801
4802
4803 switch(sig) {
4804 case SIGSEGV:
4805 case SIGBUS:
4806 case SIGFPE:
4807 case SIGPIPE:
4808 case SIGILL:
4809 case SIGXFSZ:
4810 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler);
4811 break;
4812
4813 case SHUTDOWN1_SIGNAL:
4814 case SHUTDOWN2_SIGNAL:
4815 case SHUTDOWN3_SIGNAL:
4816 case BREAK_SIGNAL:
4817 jvmHandler = (address)user_handler();
4818 break;
4819
4820 case INTERRUPT_SIGNAL:
4821 jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL);
4822 break;
4823
4824 default:
4825 if (sig == SR_signum) {
4826 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler);
4827 } else {
4828 return;
4829 }
4830 break;
4831 }
4832
4833 if (thisHandler != jvmHandler) {
4834 tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN));
4835 tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN));
4836 tty->print_cr(" found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN));
4837 // No need to check this sig any longer
4838 sigaddset(&check_signal_done, sig);
4839 // Running under non-interactive shell, SHUTDOWN2_SIGNAL will be reassigned SIG_IGN
4840 if (sig == SHUTDOWN2_SIGNAL && !isatty(fileno(stdin))) {
4841 tty->print_cr("Running in non-interactive shell, %s handler is replaced by shell",
4842 exception_name(sig, buf, O_BUFLEN));
4843 }
4844 } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) {
4845 tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN));
4846 tty->print("expected:" PTR32_FORMAT, os::Linux::get_our_sigflags(sig));
4847 tty->print_cr(" found:" PTR32_FORMAT, act.sa_flags);
4848 // No need to check this sig any longer
4849 sigaddset(&check_signal_done, sig);
4850 }
4851
4852 // Dump all the signal
4853 if (sigismember(&check_signal_done, sig)) {
4854 print_signal_handlers(tty, buf, O_BUFLEN);
4855 }
4856 }
4857
4858 extern void report_error(char* file_name, int line_no, char* title, char* format, ...);
4859
4860 extern bool signal_name(int signo, char* buf, size_t len);
4861
4862 const char* os::exception_name(int exception_code, char* buf, size_t size) {
4863 if (0 < exception_code && exception_code <= SIGRTMAX) {
4864 // signal
4865 if (!signal_name(exception_code, buf, size)) {
4866 jio_snprintf(buf, size, "SIG%d", exception_code);
4867 }
4868 return buf;
4869 } else {
4870 return NULL;
4871 }
4872 }
4873
4874 // this is called _before_ the most of global arguments have been parsed
4875 void os::init(void) {
4876 char dummy; /* used to get a guess on initial stack address */
4877 // first_hrtime = gethrtime();
4878
4879 // With LinuxThreads the JavaMain thread pid (primordial thread)
4880 // is different than the pid of the java launcher thread.
4881 // So, on Linux, the launcher thread pid is passed to the VM
4882 // via the sun.java.launcher.pid property.
4883 // Use this property instead of getpid() if it was correctly passed.
4884 // See bug 6351349.
4885 pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid();
4886
4887 _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid();
4888
4889 clock_tics_per_sec = sysconf(_SC_CLK_TCK);
4890
4891 init_random(1234567);
4892
4893 ThreadCritical::initialize();
4894
4895 Linux::set_page_size(sysconf(_SC_PAGESIZE));
4896 if (Linux::page_size() == -1) {
4897 fatal(err_msg("os_linux.cpp: os::init: sysconf failed (%s)",
4898 strerror(errno)));
4899 }
4900 init_page_sizes((size_t) Linux::page_size());
4901
4902 Linux::initialize_system_info();
4903
4904 // main_thread points to the aboriginal thread
4905 Linux::_main_thread = pthread_self();
4906
4907 Linux::clock_init();
4908 initial_time_count = javaTimeNanos();
4909
4910 // pthread_condattr initialization for monotonic clock
4911 int status;
4912 pthread_condattr_t* _condattr = os::Linux::condAttr();
4913 if ((status = pthread_condattr_init(_condattr)) != 0) {
4914 fatal(err_msg("pthread_condattr_init: %s", strerror(status)));
4915 }
4916 // Only set the clock if CLOCK_MONOTONIC is available
4917 if (Linux::supports_monotonic_clock()) {
4918 if ((status = pthread_condattr_setclock(_condattr, CLOCK_MONOTONIC)) != 0) {
4919 if (status == EINVAL) {
4920 warning("Unable to use monotonic clock with relative timed-waits" \
4921 " - changes to the time-of-day clock may have adverse affects");
4922 } else {
4923 fatal(err_msg("pthread_condattr_setclock: %s", strerror(status)));
4924 }
4925 }
4926 }
4927 // else it defaults to CLOCK_REALTIME
4928
4929 pthread_mutex_init(&dl_mutex, NULL);
4930
4931 // If the pagesize of the VM is greater than 8K determine the appropriate
4932 // number of initial guard pages. The user can change this with the
4933 // command line arguments, if needed.
4934 if (vm_page_size() > (int)Linux::vm_default_page_size()) {
4935 StackYellowPages = 1;
4936 StackRedPages = 1;
4937 StackShadowPages = round_to((StackShadowPages*Linux::vm_default_page_size()), vm_page_size()) / vm_page_size();
4938 }
4939 }
4940
4941 // To install functions for atexit system call
4942 extern "C" {
4943 static void perfMemory_exit_helper() {
4944 perfMemory_exit();
4945 }
4946 }
4947
4948 // this is called _after_ the global arguments have been parsed
4949 jint os::init_2(void)
4950 {
4951 Linux::fast_thread_clock_init();
4952
4953 // Allocate a single page and mark it as readable for safepoint polling
4954 address polling_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
4955 guarantee( polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page" );
4956
4957 os::set_polling_page( polling_page );
4958
4959 #ifndef PRODUCT
4960 if(Verbose && PrintMiscellaneous)
4961 tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n", (intptr_t)polling_page);
4962 #endif
4963
4964 if (!UseMembar) {
4965 address mem_serialize_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
4966 guarantee( mem_serialize_page != MAP_FAILED, "mmap Failed for memory serialize page");
4967 os::set_memory_serialize_page( mem_serialize_page );
4968
4969 #ifndef PRODUCT
4970 if(Verbose && PrintMiscellaneous)
4971 tty->print("[Memory Serialize Page address: " INTPTR_FORMAT "]\n", (intptr_t)mem_serialize_page);
4972 #endif
4973 }
4974
4975 // initialize suspend/resume support - must do this before signal_sets_init()
4976 if (SR_initialize() != 0) {
4977 perror("SR_initialize failed");
4978 return JNI_ERR;
4979 }
4980
4981 Linux::signal_sets_init();
4982 Linux::install_signal_handlers();
4983
4984 // Check minimum allowable stack size for thread creation and to initialize
4985 // the java system classes, including StackOverflowError - depends on page
4986 // size. Add a page for compiler2 recursion in main thread.
4987 // Add in 2*BytesPerWord times page size to account for VM stack during
4988 // class initialization depending on 32 or 64 bit VM.
4989 os::Linux::min_stack_allowed = MAX2(os::Linux::min_stack_allowed,
4990 (size_t)(StackYellowPages+StackRedPages+StackShadowPages) * Linux::page_size() +
4991 (2*BytesPerWord COMPILER2_PRESENT(+1)) * Linux::vm_default_page_size());
4992
4993 size_t threadStackSizeInBytes = ThreadStackSize * K;
4994 if (threadStackSizeInBytes != 0 &&
4995 threadStackSizeInBytes < os::Linux::min_stack_allowed) {
4996 tty->print_cr("\nThe stack size specified is too small, "
4997 "Specify at least %dk",
4998 os::Linux::min_stack_allowed/ K);
4999 return JNI_ERR;
5000 }
5001
5002 // Make the stack size a multiple of the page size so that
5003 // the yellow/red zones can be guarded.
5004 JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes,
5005 vm_page_size()));
5006
5007 Linux::capture_initial_stack(JavaThread::stack_size_at_create());
5008
5009 #if defined(IA32)
5010 workaround_expand_exec_shield_cs_limit();
5011 #endif
5012
5013 Linux::libpthread_init();
5014 if (PrintMiscellaneous && (Verbose || WizardMode)) {
5015 tty->print_cr("[HotSpot is running with %s, %s(%s)]\n",
5016 Linux::glibc_version(), Linux::libpthread_version(),
5017 Linux::is_floating_stack() ? "floating stack" : "fixed stack");
5018 }
5019
5020 if (UseNUMA) {
5021 if (!Linux::libnuma_init()) {
5022 UseNUMA = false;
5023 } else {
5024 if ((Linux::numa_max_node() < 1)) {
5025 // There's only one node(they start from 0), disable NUMA.
5026 UseNUMA = false;
5027 }
5028 }
5029 // With SHM and HugeTLBFS large pages we cannot uncommit a page, so there's no way
5030 // we can make the adaptive lgrp chunk resizing work. If the user specified
5031 // both UseNUMA and UseLargePages (or UseSHM/UseHugeTLBFS) on the command line - warn and
5032 // disable adaptive resizing.
5033 if (UseNUMA && UseLargePages && !can_commit_large_page_memory()) {
5034 if (FLAG_IS_DEFAULT(UseNUMA)) {
5035 UseNUMA = false;
5036 } else {
5037 if (FLAG_IS_DEFAULT(UseLargePages) &&
5038 FLAG_IS_DEFAULT(UseSHM) &&
5039 FLAG_IS_DEFAULT(UseHugeTLBFS)) {
5040 UseLargePages = false;
5041 } else {
5042 warning("UseNUMA is not fully compatible with SHM/HugeTLBFS large pages, disabling adaptive resizing");
5043 UseAdaptiveSizePolicy = false;
5044 UseAdaptiveNUMAChunkSizing = false;
5045 }
5046 }
5047 }
5048 if (!UseNUMA && ForceNUMA) {
5049 UseNUMA = true;
5050 }
5051 }
5052
5053 if (MaxFDLimit) {
5054 // set the number of file descriptors to max. print out error
5055 // if getrlimit/setrlimit fails but continue regardless.
5056 struct rlimit nbr_files;
5057 int status = getrlimit(RLIMIT_NOFILE, &nbr_files);
5058 if (status != 0) {
5059 if (PrintMiscellaneous && (Verbose || WizardMode))
5060 perror("os::init_2 getrlimit failed");
5061 } else {
5062 nbr_files.rlim_cur = nbr_files.rlim_max;
5063 status = setrlimit(RLIMIT_NOFILE, &nbr_files);
5064 if (status != 0) {
5065 if (PrintMiscellaneous && (Verbose || WizardMode))
5066 perror("os::init_2 setrlimit failed");
5067 }
5068 }
5069 }
5070
5071 // Initialize lock used to serialize thread creation (see os::create_thread)
5072 Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false));
5073
5074 // at-exit methods are called in the reverse order of their registration.
5075 // atexit functions are called on return from main or as a result of a
5076 // call to exit(3C). There can be only 32 of these functions registered
5077 // and atexit() does not set errno.
5078
5079 if (PerfAllowAtExitRegistration) {
5080 // only register atexit functions if PerfAllowAtExitRegistration is set.
5081 // atexit functions can be delayed until process exit time, which
5082 // can be problematic for embedded VM situations. Embedded VMs should
5083 // call DestroyJavaVM() to assure that VM resources are released.
5084
5085 // note: perfMemory_exit_helper atexit function may be removed in
5086 // the future if the appropriate cleanup code can be added to the
5087 // VM_Exit VMOperation's doit method.
5088 if (atexit(perfMemory_exit_helper) != 0) {
5089 warning("os::init_2 atexit(perfMemory_exit_helper) failed");
5090 }
5091 }
5092
5093 // initialize thread priority policy
5094 prio_init();
5095
5096 return JNI_OK;
5097 }
5098
5099 // Mark the polling page as unreadable
5100 void os::make_polling_page_unreadable(void) {
5101 if( !guard_memory((char*)_polling_page, Linux::page_size()) )
5102 fatal("Could not disable polling page");
5103 };
5104
5105 // Mark the polling page as readable
5106 void os::make_polling_page_readable(void) {
5107 if( !linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) {
5108 fatal("Could not enable polling page");
5109 }
5110 };
5111
5112 static int os_cpu_count(const cpu_set_t* cpus) {
5113 int count = 0;
5114 // only look up to the number of configured processors
5115 for (int i = 0; i < os::processor_count(); i++) {
5116 if (CPU_ISSET(i, cpus)) {
5117 count++;
5118 }
5119 }
5120 return count;
5121 }
5122
5123 // Get the current number of available processors for this process.
5124 // This value can change at any time during a process's lifetime.
5125 // sched_getaffinity gives an accurate answer as it accounts for cpusets.
5126 // If anything goes wrong we fallback to returning the number of online
5127 // processors - which can be greater than the number available to the process.
5128 int os::active_processor_count() {
5129 cpu_set_t cpus; // can represent at most 1024 (CPU_SETSIZE) processors
5130 int cpus_size = sizeof(cpu_set_t);
5131 int cpu_count = 0;
5132
5133 // pid 0 means the current thread - which we have to assume represents the process
5134 if (sched_getaffinity(0, cpus_size, &cpus) == 0) {
5135 cpu_count = os_cpu_count(&cpus);
5136 if (PrintActiveCpus) {
5137 tty->print_cr("active_processor_count: sched_getaffinity processor count: %d", cpu_count);
5138 }
5139 }
5140 else {
5141 cpu_count = ::sysconf(_SC_NPROCESSORS_ONLN);
5142 warning("sched_getaffinity failed (%s)- using online processor count (%d) "
5143 "which may exceed available processors", strerror(errno), cpu_count);
5144 }
5145
5146 assert(cpu_count > 0 && cpu_count <= processor_count(), "sanity check");
5147 return cpu_count;
5148 }
5149
5150 void os::set_native_thread_name(const char *name) {
5151 // Not yet implemented.
5152 return;
5153 }
5154
5155 bool os::distribute_processes(uint length, uint* distribution) {
5156 // Not yet implemented.
5157 return false;
5158 }
5159
5160 bool os::bind_to_processor(uint processor_id) {
5161 // Not yet implemented.
5162 return false;
5163 }
5164
5165 ///
5166
5167 void os::SuspendedThreadTask::internal_do_task() {
5168 if (do_suspend(_thread->osthread())) {
5169 SuspendedThreadTaskContext context(_thread, _thread->osthread()->ucontext());
5170 do_task(context);
5171 do_resume(_thread->osthread());
5172 }
5173 }
5174
5175 class PcFetcher : public os::SuspendedThreadTask {
5176 public:
5177 PcFetcher(Thread* thread) : os::SuspendedThreadTask(thread) {}
5178 ExtendedPC result();
5179 protected:
5180 void do_task(const os::SuspendedThreadTaskContext& context);
5181 private:
5182 ExtendedPC _epc;
5183 };
5184
5185 ExtendedPC PcFetcher::result() {
5186 guarantee(is_done(), "task is not done yet.");
5187 return _epc;
5188 }
5189
5190 void PcFetcher::do_task(const os::SuspendedThreadTaskContext& context) {
5191 Thread* thread = context.thread();
5192 OSThread* osthread = thread->osthread();
5193 if (osthread->ucontext() != NULL) {
5194 _epc = os::Linux::ucontext_get_pc((ucontext_t *) context.ucontext());
5195 } else {
5196 // NULL context is unexpected, double-check this is the VMThread
5197 guarantee(thread->is_VM_thread(), "can only be called for VMThread");
5198 }
5199 }
5200
5201 // Suspends the target using the signal mechanism and then grabs the PC before
5202 // resuming the target. Used by the flat-profiler only
5203 ExtendedPC os::get_thread_pc(Thread* thread) {
5204 // Make sure that it is called by the watcher for the VMThread
5205 assert(Thread::current()->is_Watcher_thread(), "Must be watcher");
5206 assert(thread->is_VM_thread(), "Can only be called for VMThread");
5207
5208 PcFetcher fetcher(thread);
5209 fetcher.run();
5210 return fetcher.result();
5211 }
5212
5213 int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond, pthread_mutex_t *_mutex, const struct timespec *_abstime)
5214 {
5215 if (is_NPTL()) {
5216 return pthread_cond_timedwait(_cond, _mutex, _abstime);
5217 } else {
5218 // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control
5219 // word back to default 64bit precision if condvar is signaled. Java
5220 // wants 53bit precision. Save and restore current value.
5221 int fpu = get_fpu_control_word();
5222 int status = pthread_cond_timedwait(_cond, _mutex, _abstime);
5223 set_fpu_control_word(fpu);
5224 return status;
5225 }
5226 }
5227
5228 ////////////////////////////////////////////////////////////////////////////////
5229 // debug support
5230
5231 bool os::find(address addr, outputStream* st) {
5232 Dl_info dlinfo;
5233 memset(&dlinfo, 0, sizeof(dlinfo));
5234 if (dladdr(addr, &dlinfo) != 0) {
5235 st->print(PTR_FORMAT ": ", addr);
5236 if (dlinfo.dli_sname != NULL && dlinfo.dli_saddr != NULL) {
5237 st->print("%s+%#x", dlinfo.dli_sname,
5238 addr - (intptr_t)dlinfo.dli_saddr);
5239 } else if (dlinfo.dli_fbase != NULL) {
5240 st->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase);
5241 } else {
5242 st->print("<absolute address>");
5243 }
5244 if (dlinfo.dli_fname != NULL) {
5245 st->print(" in %s", dlinfo.dli_fname);
5246 }
5247 if (dlinfo.dli_fbase != NULL) {
5248 st->print(" at " PTR_FORMAT, dlinfo.dli_fbase);
5249 }
5250 st->cr();
5251
5252 if (Verbose) {
5253 // decode some bytes around the PC
5254 address begin = clamp_address_in_page(addr-40, addr, os::vm_page_size());
5255 address end = clamp_address_in_page(addr+40, addr, os::vm_page_size());
5256 address lowest = (address) dlinfo.dli_sname;
5257 if (!lowest) lowest = (address) dlinfo.dli_fbase;
5258 if (begin < lowest) begin = lowest;
5259 Dl_info dlinfo2;
5260 if (dladdr(end, &dlinfo2) != 0 && dlinfo2.dli_saddr != dlinfo.dli_saddr
5261 && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin)
5262 end = (address) dlinfo2.dli_saddr;
5263 Disassembler::decode(begin, end, st);
5264 }
5265 return true;
5266 }
5267 return false;
5268 }
5269
5270 ////////////////////////////////////////////////////////////////////////////////
5271 // misc
5272
5273 // This does not do anything on Linux. This is basically a hook for being
5274 // able to use structured exception handling (thread-local exception filters)
5275 // on, e.g., Win32.
5276 void
5277 os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method,
5278 JavaCallArguments* args, Thread* thread) {
5279 f(value, method, args, thread);
5280 }
5281
5282 void os::print_statistics() {
5283 }
5284
5285 int os::message_box(const char* title, const char* message) {
5286 int i;
5287 fdStream err(defaultStream::error_fd());
5288 for (i = 0; i < 78; i++) err.print_raw("=");
5289 err.cr();
5290 err.print_raw_cr(title);
5291 for (i = 0; i < 78; i++) err.print_raw("-");
5292 err.cr();
5293 err.print_raw_cr(message);
5294 for (i = 0; i < 78; i++) err.print_raw("=");
5295 err.cr();
5296
5297 char buf[16];
5298 // Prevent process from exiting upon "read error" without consuming all CPU
5299 while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); }
5300
5301 return buf[0] == 'y' || buf[0] == 'Y';
5302 }
5303
5304 int os::stat(const char *path, struct stat *sbuf) {
5305 char pathbuf[MAX_PATH];
5306 if (strlen(path) > MAX_PATH - 1) {
5307 errno = ENAMETOOLONG;
5308 return -1;
5309 }
5310 os::native_path(strcpy(pathbuf, path));
5311 return ::stat(pathbuf, sbuf);
5312 }
5313
5314 bool os::check_heap(bool force) {
5315 return true;
5316 }
5317
5318 int local_vsnprintf(char* buf, size_t count, const char* format, va_list args) {
5319 return ::vsnprintf(buf, count, format, args);
5320 }
5321
5322 // Is a (classpath) directory empty?
5323 bool os::dir_is_empty(const char* path) {
5324 DIR *dir = NULL;
5325 struct dirent *ptr;
5326
5327 dir = opendir(path);
5328 if (dir == NULL) return true;
5329
5330 /* Scan the directory */
5331 bool result = true;
5332 char buf[sizeof(struct dirent) + MAX_PATH];
5333 while (result && (ptr = ::readdir(dir)) != NULL) {
5334 if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) {
5335 result = false;
5336 }
5337 }
5338 closedir(dir);
5339 return result;
5340 }
5341
5342 // This code originates from JDK's sysOpen and open64_w
5343 // from src/solaris/hpi/src/system_md.c
5344
5345 #ifndef O_DELETE
5346 #define O_DELETE 0x10000
5347 #endif
5348
5349 // Open a file. Unlink the file immediately after open returns
5350 // if the specified oflag has the O_DELETE flag set.
5351 // O_DELETE is used only in j2se/src/share/native/java/util/zip/ZipFile.c
5352
5353 int os::open(const char *path, int oflag, int mode) {
5354
5355 if (strlen(path) > MAX_PATH - 1) {
5356 errno = ENAMETOOLONG;
5357 return -1;
5358 }
5359 int fd;
5360 int o_delete = (oflag & O_DELETE);
5361 oflag = oflag & ~O_DELETE;
5362
5363 fd = ::open64(path, oflag, mode);
5364 if (fd == -1) return -1;
5365
5366 //If the open succeeded, the file might still be a directory
5367 {
5368 struct stat64 buf64;
5369 int ret = ::fstat64(fd, &buf64);
5370 int st_mode = buf64.st_mode;
5371
5372 if (ret != -1) {
5373 if ((st_mode & S_IFMT) == S_IFDIR) {
5374 errno = EISDIR;
5375 ::close(fd);
5376 return -1;
5377 }
5378 } else {
5379 ::close(fd);
5380 return -1;
5381 }
5382 }
5383
5384 /*
5385 * All file descriptors that are opened in the JVM and not
5386 * specifically destined for a subprocess should have the
5387 * close-on-exec flag set. If we don't set it, then careless 3rd
5388 * party native code might fork and exec without closing all
5389 * appropriate file descriptors (e.g. as we do in closeDescriptors in
5390 * UNIXProcess.c), and this in turn might:
5391 *
5392 * - cause end-of-file to fail to be detected on some file
5393 * descriptors, resulting in mysterious hangs, or
5394 *
5395 * - might cause an fopen in the subprocess to fail on a system
5396 * suffering from bug 1085341.
5397 *
5398 * (Yes, the default setting of the close-on-exec flag is a Unix
5399 * design flaw)
5400 *
5401 * See:
5402 * 1085341: 32-bit stdio routines should support file descriptors >255
5403 * 4843136: (process) pipe file descriptor from Runtime.exec not being closed
5404 * 6339493: (process) Runtime.exec does not close all file descriptors on Solaris 9
5405 */
5406 #ifdef FD_CLOEXEC
5407 {
5408 int flags = ::fcntl(fd, F_GETFD);
5409 if (flags != -1)
5410 ::fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
5411 }
5412 #endif
5413
5414 if (o_delete != 0) {
5415 ::unlink(path);
5416 }
5417 return fd;
5418 }
5419
5420
5421 // create binary file, rewriting existing file if required
5422 int os::create_binary_file(const char* path, bool rewrite_existing) {
5423 int oflags = O_WRONLY | O_CREAT;
5424 if (!rewrite_existing) {
5425 oflags |= O_EXCL;
5426 }
5427 return ::open64(path, oflags, S_IREAD | S_IWRITE);
5428 }
5429
5430 // return current position of file pointer
5431 jlong os::current_file_offset(int fd) {
5432 return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR);
5433 }
5434
5435 // move file pointer to the specified offset
5436 jlong os::seek_to_file_offset(int fd, jlong offset) {
5437 return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET);
5438 }
5439
5440 // This code originates from JDK's sysAvailable
5441 // from src/solaris/hpi/src/native_threads/src/sys_api_td.c
5442
5443 int os::available(int fd, jlong *bytes) {
5444 jlong cur, end;
5445 int mode;
5446 struct stat64 buf64;
5447
5448 if (::fstat64(fd, &buf64) >= 0) {
5449 mode = buf64.st_mode;
5450 if (S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) {
5451 /*
5452 * XXX: is the following call interruptible? If so, this might
5453 * need to go through the INTERRUPT_IO() wrapper as for other
5454 * blocking, interruptible calls in this file.
5455 */
5456 int n;
5457 if (::ioctl(fd, FIONREAD, &n) >= 0) {
5458 *bytes = n;
5459 return 1;
5460 }
5461 }
5462 }
5463 if ((cur = ::lseek64(fd, 0L, SEEK_CUR)) == -1) {
5464 return 0;
5465 } else if ((end = ::lseek64(fd, 0L, SEEK_END)) == -1) {
5466 return 0;
5467 } else if (::lseek64(fd, cur, SEEK_SET) == -1) {
5468 return 0;
5469 }
5470 *bytes = end - cur;
5471 return 1;
5472 }
5473
5474 int os::socket_available(int fd, jint *pbytes) {
5475 // Linux doc says EINTR not returned, unlike Solaris
5476 int ret = ::ioctl(fd, FIONREAD, pbytes);
5477
5478 //%% note ioctl can return 0 when successful, JVM_SocketAvailable
5479 // is expected to return 0 on failure and 1 on success to the jdk.
5480 return (ret < 0) ? 0 : 1;
5481 }
5482
5483 // Map a block of memory.
5484 char* os::pd_map_memory(int fd, const char* file_name, size_t file_offset,
5485 char *addr, size_t bytes, bool read_only,
5486 bool allow_exec) {
5487 int prot;
5488 int flags = MAP_PRIVATE;
5489
5490 if (read_only) {
5491 prot = PROT_READ;
5492 } else {
5493 prot = PROT_READ | PROT_WRITE;
5494 }
5495
5496 if (allow_exec) {
5497 prot |= PROT_EXEC;
5498 }
5499
5500 if (addr != NULL) {
5501 flags |= MAP_FIXED;
5502 }
5503
5504 char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags,
5505 fd, file_offset);
5506 if (mapped_address == MAP_FAILED) {
5507 return NULL;
5508 }
5509 return mapped_address;
5510 }
5511
5512
5513 // Remap a block of memory.
5514 char* os::pd_remap_memory(int fd, const char* file_name, size_t file_offset,
5515 char *addr, size_t bytes, bool read_only,
5516 bool allow_exec) {
5517 // same as map_memory() on this OS
5518 return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only,
5519 allow_exec);
5520 }
5521
5522
5523 // Unmap a block of memory.
5524 bool os::pd_unmap_memory(char* addr, size_t bytes) {
5525 return munmap(addr, bytes) == 0;
5526 }
5527
5528 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time);
5529
5530 static clockid_t thread_cpu_clockid(Thread* thread) {
5531 pthread_t tid = thread->osthread()->pthread_id();
5532 clockid_t clockid;
5533
5534 // Get thread clockid
5535 int rc = os::Linux::pthread_getcpuclockid(tid, &clockid);
5536 assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code");
5537 return clockid;
5538 }
5539
5540 // current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool)
5541 // are used by JVM M&M and JVMTI to get user+sys or user CPU time
5542 // of a thread.
5543 //
5544 // current_thread_cpu_time() and thread_cpu_time(Thread*) returns
5545 // the fast estimate available on the platform.
5546
5547 jlong os::current_thread_cpu_time() {
5548 if (os::Linux::supports_fast_thread_cpu_time()) {
5549 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
5550 } else {
5551 // return user + sys since the cost is the same
5552 return slow_thread_cpu_time(Thread::current(), true /* user + sys */);
5553 }
5554 }
5555
5556 jlong os::thread_cpu_time(Thread* thread) {
5557 // consistent with what current_thread_cpu_time() returns
5558 if (os::Linux::supports_fast_thread_cpu_time()) {
5559 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread));
5560 } else {
5561 return slow_thread_cpu_time(thread, true /* user + sys */);
5562 }
5563 }
5564
5565 jlong os::current_thread_cpu_time(bool user_sys_cpu_time) {
5566 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
5567 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
5568 } else {
5569 return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time);
5570 }
5571 }
5572
5573 jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
5574 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
5575 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread));
5576 } else {
5577 return slow_thread_cpu_time(thread, user_sys_cpu_time);
5578 }
5579 }
5580
5581 //
5582 // -1 on error.
5583 //
5584
5585 PRAGMA_DIAG_PUSH
5586 PRAGMA_FORMAT_NONLITERAL_IGNORED
5587 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
5588 static bool proc_task_unchecked = true;
5589 static const char *proc_stat_path = "/proc/%d/stat";
5590 pid_t tid = thread->osthread()->thread_id();
5591 char *s;
5592 char stat[2048];
5593 int statlen;
5594 char proc_name[64];
5595 int count;
5596 long sys_time, user_time;
5597 char cdummy;
5598 int idummy;
5599 long ldummy;
5600 FILE *fp;
5601
5602 // The /proc/<tid>/stat aggregates per-process usage on
5603 // new Linux kernels 2.6+ where NPTL is supported.
5604 // The /proc/self/task/<tid>/stat still has the per-thread usage.
5605 // See bug 6328462.
5606 // There possibly can be cases where there is no directory
5607 // /proc/self/task, so we check its availability.
5608 if (proc_task_unchecked && os::Linux::is_NPTL()) {
5609 // This is executed only once
5610 proc_task_unchecked = false;
5611 fp = fopen("/proc/self/task", "r");
5612 if (fp != NULL) {
5613 proc_stat_path = "/proc/self/task/%d/stat";
5614 fclose(fp);
5615 }
5616 }
5617
5618 sprintf(proc_name, proc_stat_path, tid);
5619 fp = fopen(proc_name, "r");
5620 if ( fp == NULL ) return -1;
5621 statlen = fread(stat, 1, 2047, fp);
5622 stat[statlen] = '\0';
5623 fclose(fp);
5624
5625 // Skip pid and the command string. Note that we could be dealing with
5626 // weird command names, e.g. user could decide to rename java launcher
5627 // to "java 1.4.2 :)", then the stat file would look like
5628 // 1234 (java 1.4.2 :)) R ... ...
5629 // We don't really need to know the command string, just find the last
5630 // occurrence of ")" and then start parsing from there. See bug 4726580.
5631 s = strrchr(stat, ')');
5632 if (s == NULL ) return -1;
5633
5634 // Skip blank chars
5635 do s++; while (isspace(*s));
5636
5637 count = sscanf(s,"%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu",
5638 &cdummy, &idummy, &idummy, &idummy, &idummy, &idummy,
5639 &ldummy, &ldummy, &ldummy, &ldummy, &ldummy,
5640 &user_time, &sys_time);
5641 if ( count != 13 ) return -1;
5642 if (user_sys_cpu_time) {
5643 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec);
5644 } else {
5645 return (jlong)user_time * (1000000000 / clock_tics_per_sec);
5646 }
5647 }
5648 PRAGMA_DIAG_POP
5649
5650 void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
5651 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits
5652 info_ptr->may_skip_backward = false; // elapsed time not wall time
5653 info_ptr->may_skip_forward = false; // elapsed time not wall time
5654 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned
5655 }
5656
5657 void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
5658 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits
5659 info_ptr->may_skip_backward = false; // elapsed time not wall time
5660 info_ptr->may_skip_forward = false; // elapsed time not wall time
5661 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned
5662 }
5663
5664 bool os::is_thread_cpu_time_supported() {
5665 return true;
5666 }
5667
5668 // System loadavg support. Returns -1 if load average cannot be obtained.
5669 // Linux doesn't yet have a (official) notion of processor sets,
5670 // so just return the system wide load average.
5671 int os::loadavg(double loadavg[], int nelem) {
5672 return ::getloadavg(loadavg, nelem);
5673 }
5674
5675 void os::pause() {
5676 char filename[MAX_PATH];
5677 if (PauseAtStartupFile && PauseAtStartupFile[0]) {
5678 jio_snprintf(filename, MAX_PATH, PauseAtStartupFile);
5679 } else {
5680 jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id());
5681 }
5682
5683 int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
5684 if (fd != -1) {
5685 struct stat buf;
5686 ::close(fd);
5687 while (::stat(filename, &buf) == 0) {
5688 (void)::poll(NULL, 0, 100);
5689 }
5690 } else {
5691 jio_fprintf(stderr,
5692 "Could not open pause file '%s', continuing immediately.\n", filename);
5693 }
5694 }
5695
5696
5697 // Refer to the comments in os_solaris.cpp park-unpark.
5698 //
5699 // Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can
5700 // hang indefinitely. For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable.
5701 // For specifics regarding the bug see GLIBC BUGID 261237 :
5702 // http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html.
5703 // Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future
5704 // will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar
5705 // is used. (The simple C test-case provided in the GLIBC bug report manifests the
5706 // hang). The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos()
5707 // and monitorenter when we're using 1-0 locking. All those operations may result in
5708 // calls to pthread_cond_timedwait(). Using LD_ASSUME_KERNEL to use an older version
5709 // of libpthread avoids the problem, but isn't practical.
5710 //
5711 // Possible remedies:
5712 //
5713 // 1. Establish a minimum relative wait time. 50 to 100 msecs seems to work.
5714 // This is palliative and probabilistic, however. If the thread is preempted
5715 // between the call to compute_abstime() and pthread_cond_timedwait(), more
5716 // than the minimum period may have passed, and the abstime may be stale (in the
5717 // past) resultin in a hang. Using this technique reduces the odds of a hang
5718 // but the JVM is still vulnerable, particularly on heavily loaded systems.
5719 //
5720 // 2. Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead
5721 // of the usual flag-condvar-mutex idiom. The write side of the pipe is set
5722 // NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo)
5723 // reduces to poll()+read(). This works well, but consumes 2 FDs per extant
5724 // thread.
5725 //
5726 // 3. Embargo pthread_cond_timedwait() and implement a native "chron" thread
5727 // that manages timeouts. We'd emulate pthread_cond_timedwait() by enqueuing
5728 // a timeout request to the chron thread and then blocking via pthread_cond_wait().
5729 // This also works well. In fact it avoids kernel-level scalability impediments
5730 // on certain platforms that don't handle lots of active pthread_cond_timedwait()
5731 // timers in a graceful fashion.
5732 //
5733 // 4. When the abstime value is in the past it appears that control returns
5734 // correctly from pthread_cond_timedwait(), but the condvar is left corrupt.
5735 // Subsequent timedwait/wait calls may hang indefinitely. Given that, we
5736 // can avoid the problem by reinitializing the condvar -- by cond_destroy()
5737 // followed by cond_init() -- after all calls to pthread_cond_timedwait().
5738 // It may be possible to avoid reinitialization by checking the return
5739 // value from pthread_cond_timedwait(). In addition to reinitializing the
5740 // condvar we must establish the invariant that cond_signal() is only called
5741 // within critical sections protected by the adjunct mutex. This prevents
5742 // cond_signal() from "seeing" a condvar that's in the midst of being
5743 // reinitialized or that is corrupt. Sadly, this invariant obviates the
5744 // desirable signal-after-unlock optimization that avoids futile context switching.
5745 //
5746 // I'm also concerned that some versions of NTPL might allocate an auxilliary
5747 // structure when a condvar is used or initialized. cond_destroy() would
5748 // release the helper structure. Our reinitialize-after-timedwait fix
5749 // put excessive stress on malloc/free and locks protecting the c-heap.
5750 //
5751 // We currently use (4). See the WorkAroundNTPLTimedWaitHang flag.
5752 // It may be possible to refine (4) by checking the kernel and NTPL verisons
5753 // and only enabling the work-around for vulnerable environments.
5754
5755 // utility to compute the abstime argument to timedwait:
5756 // millis is the relative timeout time
5757 // abstime will be the absolute timeout time
5758 // TODO: replace compute_abstime() with unpackTime()
5759
5760 static struct timespec* compute_abstime(timespec* abstime, jlong millis) {
5761 if (millis < 0) millis = 0;
5762
5763 jlong seconds = millis / 1000;
5764 millis %= 1000;
5765 if (seconds > 50000000) { // see man cond_timedwait(3T)
5766 seconds = 50000000;
5767 }
5768
5769 if (os::Linux::supports_monotonic_clock()) {
5770 struct timespec now;
5771 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now);
5772 assert_status(status == 0, status, "clock_gettime");
5773 abstime->tv_sec = now.tv_sec + seconds;
5774 long nanos = now.tv_nsec + millis * NANOSECS_PER_MILLISEC;
5775 if (nanos >= NANOSECS_PER_SEC) {
5776 abstime->tv_sec += 1;
5777 nanos -= NANOSECS_PER_SEC;
5778 }
5779 abstime->tv_nsec = nanos;
5780 } else {
5781 struct timeval now;
5782 int status = gettimeofday(&now, NULL);
5783 assert(status == 0, "gettimeofday");
5784 abstime->tv_sec = now.tv_sec + seconds;
5785 long usec = now.tv_usec + millis * 1000;
5786 if (usec >= 1000000) {
5787 abstime->tv_sec += 1;
5788 usec -= 1000000;
5789 }
5790 abstime->tv_nsec = usec * 1000;
5791 }
5792 return abstime;
5793 }
5794
5795
5796 // Test-and-clear _Event, always leaves _Event set to 0, returns immediately.
5797 // Conceptually TryPark() should be equivalent to park(0).
5798
5799 int os::PlatformEvent::TryPark() {
5800 for (;;) {
5801 const int v = _Event ;
5802 guarantee ((v == 0) || (v == 1), "invariant") ;
5803 if (Atomic::cmpxchg (0, &_Event, v) == v) return v ;
5804 }
5805 }
5806
5807 void os::PlatformEvent::park() { // AKA "down()"
5808 // Invariant: Only the thread associated with the Event/PlatformEvent
5809 // may call park().
5810 // TODO: assert that _Assoc != NULL or _Assoc == Self
5811 int v ;
5812 for (;;) {
5813 v = _Event ;
5814 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ;
5815 }
5816 guarantee (v >= 0, "invariant") ;
5817 if (v == 0) {
5818 // Do this the hard way by blocking ...
5819 int status = pthread_mutex_lock(_mutex);
5820 assert_status(status == 0, status, "mutex_lock");
5821 guarantee (_nParked == 0, "invariant") ;
5822 ++ _nParked ;
5823 while (_Event < 0) {
5824 status = pthread_cond_wait(_cond, _mutex);
5825 // for some reason, under 2.7 lwp_cond_wait() may return ETIME ...
5826 // Treat this the same as if the wait was interrupted
5827 if (status == ETIME) { status = EINTR; }
5828 assert_status(status == 0 || status == EINTR, status, "cond_wait");
5829 }
5830 -- _nParked ;
5831
5832 _Event = 0 ;
5833 status = pthread_mutex_unlock(_mutex);
5834 assert_status(status == 0, status, "mutex_unlock");
5835 // Paranoia to ensure our locked and lock-free paths interact
5836 // correctly with each other.
5837 OrderAccess::fence();
5838 }
5839 guarantee (_Event >= 0, "invariant") ;
5840 }
5841
5842 int os::PlatformEvent::park(jlong millis) {
5843 guarantee (_nParked == 0, "invariant") ;
5844
5845 int v ;
5846 for (;;) {
5847 v = _Event ;
5848 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ;
5849 }
5850 guarantee (v >= 0, "invariant") ;
5851 if (v != 0) return OS_OK ;
5852
5853 // We do this the hard way, by blocking the thread.
5854 // Consider enforcing a minimum timeout value.
5855 struct timespec abst;
5856 compute_abstime(&abst, millis);
5857
5858 int ret = OS_TIMEOUT;
5859 int status = pthread_mutex_lock(_mutex);
5860 assert_status(status == 0, status, "mutex_lock");
5861 guarantee (_nParked == 0, "invariant") ;
5862 ++_nParked ;
5863
5864 // Object.wait(timo) will return because of
5865 // (a) notification
5866 // (b) timeout
5867 // (c) thread.interrupt
5868 //
5869 // Thread.interrupt and object.notify{All} both call Event::set.
5870 // That is, we treat thread.interrupt as a special case of notification.
5871 // The underlying Solaris implementation, cond_timedwait, admits
5872 // spurious/premature wakeups, but the JLS/JVM spec prevents the
5873 // JVM from making those visible to Java code. As such, we must
5874 // filter out spurious wakeups. We assume all ETIME returns are valid.
5875 //
5876 // TODO: properly differentiate simultaneous notify+interrupt.
5877 // In that case, we should propagate the notify to another waiter.
5878
5879 while (_Event < 0) {
5880 status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst);
5881 if (status != 0 && WorkAroundNPTLTimedWaitHang) {
5882 pthread_cond_destroy (_cond);
5883 pthread_cond_init (_cond, os::Linux::condAttr()) ;
5884 }
5885 assert_status(status == 0 || status == EINTR ||
5886 status == ETIME || status == ETIMEDOUT,
5887 status, "cond_timedwait");
5888 if (!FilterSpuriousWakeups) break ; // previous semantics
5889 if (status == ETIME || status == ETIMEDOUT) break ;
5890 // We consume and ignore EINTR and spurious wakeups.
5891 }
5892 --_nParked ;
5893 if (_Event >= 0) {
5894 ret = OS_OK;
5895 }
5896 _Event = 0 ;
5897 status = pthread_mutex_unlock(_mutex);
5898 assert_status(status == 0, status, "mutex_unlock");
5899 assert (_nParked == 0, "invariant") ;
5900 // Paranoia to ensure our locked and lock-free paths interact
5901 // correctly with each other.
5902 OrderAccess::fence();
5903 return ret;
5904 }
5905
5906 void os::PlatformEvent::unpark() {
5907 // Transitions for _Event:
5908 // 0 :=> 1
5909 // 1 :=> 1
5910 // -1 :=> either 0 or 1; must signal target thread
5911 // That is, we can safely transition _Event from -1 to either
5912 // 0 or 1. Forcing 1 is slightly more efficient for back-to-back
5913 // unpark() calls.
5914 // See also: "Semaphores in Plan 9" by Mullender & Cox
5915 //
5916 // Note: Forcing a transition from "-1" to "1" on an unpark() means
5917 // that it will take two back-to-back park() calls for the owning
5918 // thread to block. This has the benefit of forcing a spurious return
5919 // from the first park() call after an unpark() call which will help
5920 // shake out uses of park() and unpark() without condition variables.
5921
5922 if (Atomic::xchg(1, &_Event) >= 0) return;
5923
5924 // Wait for the thread associated with the event to vacate
5925 int status = pthread_mutex_lock(_mutex);
5926 assert_status(status == 0, status, "mutex_lock");
5927 int AnyWaiters = _nParked;
5928 assert(AnyWaiters == 0 || AnyWaiters == 1, "invariant");
5929 if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) {
5930 AnyWaiters = 0;
5931 pthread_cond_signal(_cond);
5932 }
5933 status = pthread_mutex_unlock(_mutex);
5934 assert_status(status == 0, status, "mutex_unlock");
5935 if (AnyWaiters != 0) {
5936 status = pthread_cond_signal(_cond);
5937 assert_status(status == 0, status, "cond_signal");
5938 }
5939
5940 // Note that we signal() _after dropping the lock for "immortal" Events.
5941 // This is safe and avoids a common class of futile wakeups. In rare
5942 // circumstances this can cause a thread to return prematurely from
5943 // cond_{timed}wait() but the spurious wakeup is benign and the victim will
5944 // simply re-test the condition and re-park itself.
5945 }
5946
5947
5948 // JSR166
5949 // -------------------------------------------------------
5950
5951 /*
5952 * The solaris and linux implementations of park/unpark are fairly
5953 * conservative for now, but can be improved. They currently use a
5954 * mutex/condvar pair, plus a a count.
5955 * Park decrements count if > 0, else does a condvar wait. Unpark
5956 * sets count to 1 and signals condvar. Only one thread ever waits
5957 * on the condvar. Contention seen when trying to park implies that someone
5958 * is unparking you, so don't wait. And spurious returns are fine, so there
5959 * is no need to track notifications.
5960 */
5961
5962 /*
5963 * This code is common to linux and solaris and will be moved to a
5964 * common place in dolphin.
5965 *
5966 * The passed in time value is either a relative time in nanoseconds
5967 * or an absolute time in milliseconds. Either way it has to be unpacked
5968 * into suitable seconds and nanoseconds components and stored in the
5969 * given timespec structure.
5970 * Given time is a 64-bit value and the time_t used in the timespec is only
5971 * a signed-32-bit value (except on 64-bit Linux) we have to watch for
5972 * overflow if times way in the future are given. Further on Solaris versions
5973 * prior to 10 there is a restriction (see cond_timedwait) that the specified
5974 * number of seconds, in abstime, is less than current_time + 100,000,000.
5975 * As it will be 28 years before "now + 100000000" will overflow we can
5976 * ignore overflow and just impose a hard-limit on seconds using the value
5977 * of "now + 100,000,000". This places a limit on the timeout of about 3.17
5978 * years from "now".
5979 */
5980
5981 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) {
5982 assert (time > 0, "convertTime");
5983 time_t max_secs = 0;
5984
5985 if (!os::Linux::supports_monotonic_clock() || isAbsolute) {
5986 struct timeval now;
5987 int status = gettimeofday(&now, NULL);
5988 assert(status == 0, "gettimeofday");
5989
5990 max_secs = now.tv_sec + MAX_SECS;
5991
5992 if (isAbsolute) {
5993 jlong secs = time / 1000;
5994 if (secs > max_secs) {
5995 absTime->tv_sec = max_secs;
5996 } else {
5997 absTime->tv_sec = secs;
5998 }
5999 absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC;
6000 } else {
6001 jlong secs = time / NANOSECS_PER_SEC;
6002 if (secs >= MAX_SECS) {
6003 absTime->tv_sec = max_secs;
6004 absTime->tv_nsec = 0;
6005 } else {
6006 absTime->tv_sec = now.tv_sec + secs;
6007 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000;
6008 if (absTime->tv_nsec >= NANOSECS_PER_SEC) {
6009 absTime->tv_nsec -= NANOSECS_PER_SEC;
6010 ++absTime->tv_sec; // note: this must be <= max_secs
6011 }
6012 }
6013 }
6014 } else {
6015 // must be relative using monotonic clock
6016 struct timespec now;
6017 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now);
6018 assert_status(status == 0, status, "clock_gettime");
6019 max_secs = now.tv_sec + MAX_SECS;
6020 jlong secs = time / NANOSECS_PER_SEC;
6021 if (secs >= MAX_SECS) {
6022 absTime->tv_sec = max_secs;
6023 absTime->tv_nsec = 0;
6024 } else {
6025 absTime->tv_sec = now.tv_sec + secs;
6026 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_nsec;
6027 if (absTime->tv_nsec >= NANOSECS_PER_SEC) {
6028 absTime->tv_nsec -= NANOSECS_PER_SEC;
6029 ++absTime->tv_sec; // note: this must be <= max_secs
6030 }
6031 }
6032 }
6033 assert(absTime->tv_sec >= 0, "tv_sec < 0");
6034 assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs");
6035 assert(absTime->tv_nsec >= 0, "tv_nsec < 0");
6036 assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec");
6037 }
6038
6039 void Parker::park(bool isAbsolute, jlong time) {
6040 // Ideally we'd do something useful while spinning, such
6041 // as calling unpackTime().
6042
6043 // Optional fast-path check:
6044 // Return immediately if a permit is available.
6045 // We depend on Atomic::xchg() having full barrier semantics
6046 // since we are doing a lock-free update to _counter.
6047 if (Atomic::xchg(0, &_counter) > 0) return;
6048
6049 Thread* thread = Thread::current();
6050 assert(thread->is_Java_thread(), "Must be JavaThread");
6051 JavaThread *jt = (JavaThread *)thread;
6052
6053 // Optional optimization -- avoid state transitions if there's an interrupt pending.
6054 // Check interrupt before trying to wait
6055 if (Thread::is_interrupted(thread, false)) {
6056 return;
6057 }
6058
6059 // Next, demultiplex/decode time arguments
6060 timespec absTime;
6061 if (time < 0 || (isAbsolute && time == 0) ) { // don't wait at all
6062 return;
6063 }
6064 if (time > 0) {
6065 unpackTime(&absTime, isAbsolute, time);
6066 }
6067
6068
6069 // Enter safepoint region
6070 // Beware of deadlocks such as 6317397.
6071 // The per-thread Parker:: mutex is a classic leaf-lock.
6072 // In particular a thread must never block on the Threads_lock while
6073 // holding the Parker:: mutex. If safepoints are pending both the
6074 // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock.
6075 ThreadBlockInVM tbivm(jt);
6076
6077 // Don't wait if cannot get lock since interference arises from
6078 // unblocking. Also. check interrupt before trying wait
6079 if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) {
6080 return;
6081 }
6082
6083 int status ;
6084 if (_counter > 0) { // no wait needed
6085 _counter = 0;
6086 status = pthread_mutex_unlock(_mutex);
6087 assert (status == 0, "invariant") ;
6088 // Paranoia to ensure our locked and lock-free paths interact
6089 // correctly with each other and Java-level accesses.
6090 OrderAccess::fence();
6091 return;
6092 }
6093
6094 #ifdef ASSERT
6095 // Don't catch signals while blocked; let the running threads have the signals.
6096 // (This allows a debugger to break into the running thread.)
6097 sigset_t oldsigs;
6098 sigset_t* allowdebug_blocked = os::Linux::allowdebug_blocked_signals();
6099 pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs);
6100 #endif
6101
6102 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */);
6103 jt->set_suspend_equivalent();
6104 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
6105
6106 assert(_cur_index == -1, "invariant");
6107 if (time == 0) {
6108 _cur_index = REL_INDEX; // arbitrary choice when not timed
6109 status = pthread_cond_wait (&_cond[_cur_index], _mutex) ;
6110 } else {
6111 _cur_index = isAbsolute ? ABS_INDEX : REL_INDEX;
6112 status = os::Linux::safe_cond_timedwait (&_cond[_cur_index], _mutex, &absTime) ;
6113 if (status != 0 && WorkAroundNPTLTimedWaitHang) {
6114 pthread_cond_destroy (&_cond[_cur_index]) ;
6115 pthread_cond_init (&_cond[_cur_index], isAbsolute ? NULL : os::Linux::condAttr());
6116 }
6117 }
6118 _cur_index = -1;
6119 assert_status(status == 0 || status == EINTR ||
6120 status == ETIME || status == ETIMEDOUT,
6121 status, "cond_timedwait");
6122
6123 #ifdef ASSERT
6124 pthread_sigmask(SIG_SETMASK, &oldsigs, NULL);
6125 #endif
6126
6127 _counter = 0 ;
6128 status = pthread_mutex_unlock(_mutex) ;
6129 assert_status(status == 0, status, "invariant") ;
6130 // Paranoia to ensure our locked and lock-free paths interact
6131 // correctly with each other and Java-level accesses.
6132 OrderAccess::fence();
6133
6134 // If externally suspended while waiting, re-suspend
6135 if (jt->handle_special_suspend_equivalent_condition()) {
6136 jt->java_suspend_self();
6137 }
6138 }
6139
6140 void Parker::unpark() {
6141 int s, status ;
6142 status = pthread_mutex_lock(_mutex);
6143 assert (status == 0, "invariant") ;
6144 s = _counter;
6145 _counter = 1;
6146 if (s < 1) {
6147 // thread might be parked
6148 if (_cur_index != -1) {
6149 // thread is definitely parked
6150 if (WorkAroundNPTLTimedWaitHang) {
6151 status = pthread_cond_signal (&_cond[_cur_index]);
6152 assert (status == 0, "invariant");
6153 status = pthread_mutex_unlock(_mutex);
6154 assert (status == 0, "invariant");
6155 } else {
6156 // must capture correct index before unlocking
6157 int index = _cur_index;
6158 status = pthread_mutex_unlock(_mutex);
6159 assert (status == 0, "invariant");
6160 status = pthread_cond_signal (&_cond[index]);
6161 assert (status == 0, "invariant");
6162 }
6163 } else {
6164 pthread_mutex_unlock(_mutex);
6165 assert (status == 0, "invariant") ;
6166 }
6167 } else {
6168 pthread_mutex_unlock(_mutex);
6169 assert (status == 0, "invariant") ;
6170 }
6171 }
6172
6173
6174 extern char** environ;
6175
6176 // Run the specified command in a separate process. Return its exit value,
6177 // or -1 on failure (e.g. can't fork a new process).
6178 // Unlike system(), this function can be called from signal handler. It
6179 // doesn't block SIGINT et al.
6180 int os::fork_and_exec(char* cmd) {
6181 const char * argv[4] = {"sh", "-c", cmd, NULL};
6182
6183 pid_t pid = fork();
6184
6185 if (pid < 0) {
6186 // fork failed
6187 return -1;
6188
6189 } else if (pid == 0) {
6190 // child process
6191
6192 execve("/bin/sh", (char* const*)argv, environ);
6193
6194 // execve failed
6195 _exit(-1);
6196
6197 } else {
6198 // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't
6199 // care about the actual exit code, for now.
6200
6201 int status;
6202
6203 // Wait for the child process to exit. This returns immediately if
6204 // the child has already exited. */
6205 while (waitpid(pid, &status, 0) < 0) {
6206 switch (errno) {
6207 case ECHILD: return 0;
6208 case EINTR: break;
6209 default: return -1;
6210 }
6211 }
6212
6213 if (WIFEXITED(status)) {
6214 // The child exited normally; get its exit code.
6215 return WEXITSTATUS(status);
6216 } else if (WIFSIGNALED(status)) {
6217 // The child exited because of a signal
6218 // The best value to return is 0x80 + signal number,
6219 // because that is what all Unix shells do, and because
6220 // it allows callers to distinguish between process exit and
6221 // process death by signal.
6222 return 0x80 + WTERMSIG(status);
6223 } else {
6224 // Unknown exit code; pass it through
6225 return status;
6226 }
6227 }
6228 }
6229
6230 // is_headless_jre()
6231 //
6232 // Test for the existence of xawt/libmawt.so or libawt_xawt.so
6233 // in order to report if we are running in a headless jre
6234 //
6235 // Since JDK8 xawt/libmawt.so was moved into the same directory
6236 // as libawt.so, and renamed libawt_xawt.so
6237 //
6238 bool os::is_headless_jre() {
6239 struct stat statbuf;
6240 char buf[MAXPATHLEN];
6241 char libmawtpath[MAXPATHLEN];
6242 const char *xawtstr = "/xawt/libmawt.so";
6243 const char *new_xawtstr = "/libawt_xawt.so";
6244 char *p;
6245
6246 // Get path to libjvm.so
6247 os::jvm_path(buf, sizeof(buf));
6248
6249 // Get rid of libjvm.so
6250 p = strrchr(buf, '/');
6251 if (p == NULL) return false;
6252 else *p = '\0';
6253
6254 // Get rid of client or server
6255 p = strrchr(buf, '/');
6256 if (p == NULL) return false;
6257 else *p = '\0';
6258
6259 // check xawt/libmawt.so
6260 strcpy(libmawtpath, buf);
6261 strcat(libmawtpath, xawtstr);
6262 if (::stat(libmawtpath, &statbuf) == 0) return false;
6263
6264 // check libawt_xawt.so
6265 strcpy(libmawtpath, buf);
6266 strcat(libmawtpath, new_xawtstr);
6267 if (::stat(libmawtpath, &statbuf) == 0) return false;
6268
6269 return true;
6270 }
6271
6272 // Get the default path to the core file
6273 // Returns the length of the string
6274 int os::get_core_path(char* buffer, size_t bufferSize) {
6275 const char* p = get_current_directory(buffer, bufferSize);
6276
6277 if (p == NULL) {
6278 assert(p != NULL, "failed to get current directory");
6279 return 0;
6280 }
6281
6282 return strlen(buffer);
6283 }
6284
6285 /////////////// Unit tests ///////////////
6286
6287 #ifndef PRODUCT
6288
6289 #define test_log(...) \
6290 do {\
6291 if (VerboseInternalVMTests) { \
6292 tty->print_cr(__VA_ARGS__); \
6293 tty->flush(); \
6294 }\
6295 } while (false)
6296
6297 class TestReserveMemorySpecial : AllStatic {
6298 public:
6299 static void small_page_write(void* addr, size_t size) {
6300 size_t page_size = os::vm_page_size();
6301
6302 char* end = (char*)addr + size;
6303 for (char* p = (char*)addr; p < end; p += page_size) {
6304 *p = 1;
6305 }
6306 }
6307
6308 static void test_reserve_memory_special_huge_tlbfs_only(size_t size) {
6309 if (!UseHugeTLBFS) {
6310 return;
6311 }
6312
6313 test_log("test_reserve_memory_special_huge_tlbfs_only(" SIZE_FORMAT ")", size);
6314
6315 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_only(size, NULL, false);
6316
6317 if (addr != NULL) {
6318 small_page_write(addr, size);
6319
6320 os::Linux::release_memory_special_huge_tlbfs(addr, size);
6321 }
6322 }
6323
6324 static void test_reserve_memory_special_huge_tlbfs_only() {
6325 if (!UseHugeTLBFS) {
6326 return;
6327 }
6328
6329 size_t lp = os::large_page_size();
6330
6331 for (size_t size = lp; size <= lp * 10; size += lp) {
6332 test_reserve_memory_special_huge_tlbfs_only(size);
6333 }
6334 }
6335
6336 static void test_reserve_memory_special_huge_tlbfs_mixed() {
6337 size_t lp = os::large_page_size();
6338 size_t ag = os::vm_allocation_granularity();
6339
6340 // sizes to test
6341 const size_t sizes[] = {
6342 lp, lp + ag, lp + lp / 2, lp * 2,
6343 lp * 2 + ag, lp * 2 - ag, lp * 2 + lp / 2,
6344 lp * 10, lp * 10 + lp / 2
6345 };
6346 const int num_sizes = sizeof(sizes) / sizeof(size_t);
6347
6348 // For each size/alignment combination, we test three scenarios:
6349 // 1) with req_addr == NULL
6350 // 2) with a non-null req_addr at which we expect to successfully allocate
6351 // 3) with a non-null req_addr which contains a pre-existing mapping, at which we
6352 // expect the allocation to either fail or to ignore req_addr
6353
6354 // Pre-allocate two areas; they shall be as large as the largest allocation
6355 // and aligned to the largest alignment we will be testing.
6356 const size_t mapping_size = sizes[num_sizes - 1] * 2;
6357 char* const mapping1 = (char*) ::mmap(NULL, mapping_size,
6358 PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE,
6359 -1, 0);
6360 assert(mapping1 != MAP_FAILED, "should work");
6361
6362 char* const mapping2 = (char*) ::mmap(NULL, mapping_size,
6363 PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE,
6364 -1, 0);
6365 assert(mapping2 != MAP_FAILED, "should work");
6366
6367 // Unmap the first mapping, but leave the second mapping intact: the first
6368 // mapping will serve as a value for a "good" req_addr (case 2). The second
6369 // mapping, still intact, as "bad" req_addr (case 3).
6370 ::munmap(mapping1, mapping_size);
6371
6372 // Case 1
6373 test_log("%s, req_addr NULL:", __FUNCTION__);
6374 test_log("size align result");
6375
6376 for (int i = 0; i < num_sizes; i++) {
6377 const size_t size = sizes[i];
6378 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) {
6379 char* p = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, NULL, false);
6380 test_log(SIZE_FORMAT_HEX " " SIZE_FORMAT_HEX " -> " PTR_FORMAT " %s",
6381 size, alignment, p, (p != NULL ? "" : "(failed)"));
6382 if (p != NULL) {
6383 assert(is_ptr_aligned(p, alignment), "must be");
6384 small_page_write(p, size);
6385 os::Linux::release_memory_special_huge_tlbfs(p, size);
6386 }
6387 }
6388 }
6389
6390 // Case 2
6391 test_log("%s, req_addr non-NULL:", __FUNCTION__);
6392 test_log("size align req_addr result");
6393
6394 for (int i = 0; i < num_sizes; i++) {
6395 const size_t size = sizes[i];
6396 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) {
6397 char* const req_addr = (char*) align_ptr_up(mapping1, alignment);
6398 char* p = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, req_addr, false);
6399 test_log(SIZE_FORMAT_HEX " " SIZE_FORMAT_HEX " " PTR_FORMAT " -> " PTR_FORMAT " %s",
6400 size, alignment, req_addr, p,
6401 ((p != NULL ? (p == req_addr ? "(exact match)" : "") : "(failed)")));
6402 if (p != NULL) {
6403 assert(p == req_addr, "must be");
6404 small_page_write(p, size);
6405 os::Linux::release_memory_special_huge_tlbfs(p, size);
6406 }
6407 }
6408 }
6409
6410 // Case 3
6411 test_log("%s, req_addr non-NULL with preexisting mapping:", __FUNCTION__);
6412 test_log("size align req_addr result");
6413
6414 for (int i = 0; i < num_sizes; i++) {
6415 const size_t size = sizes[i];
6416 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) {
6417 char* const req_addr = (char*) align_ptr_up(mapping2, alignment);
6418 char* p = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, req_addr, false);
6419 test_log(SIZE_FORMAT_HEX " " SIZE_FORMAT_HEX " " PTR_FORMAT " -> " PTR_FORMAT " %s",
6420 size, alignment, req_addr, p,
6421 ((p != NULL ? "" : "(failed)")));
6422 // as the area around req_addr contains already existing mappings, the API should always
6423 // return NULL (as per contract, it cannot return another address)
6424 assert(p == NULL, "must be");
6425 }
6426 }
6427
6428 ::munmap(mapping2, mapping_size);
6429
6430 }
6431
6432 static void test_reserve_memory_special_huge_tlbfs() {
6433 if (!UseHugeTLBFS) {
6434 return;
6435 }
6436
6437 test_reserve_memory_special_huge_tlbfs_only();
6438 test_reserve_memory_special_huge_tlbfs_mixed();
6439 }
6440
6441 static void test_reserve_memory_special_shm(size_t size, size_t alignment) {
6442 if (!UseSHM) {
6443 return;
6444 }
6445
6446 test_log("test_reserve_memory_special_shm(" SIZE_FORMAT ", " SIZE_FORMAT ")", size, alignment);
6447
6448 char* addr = os::Linux::reserve_memory_special_shm(size, alignment, NULL, false);
6449
6450 if (addr != NULL) {
6451 assert(is_ptr_aligned(addr, alignment), "Check");
6452 assert(is_ptr_aligned(addr, os::large_page_size()), "Check");
6453
6454 small_page_write(addr, size);
6455
6456 os::Linux::release_memory_special_shm(addr, size);
6457 }
6458 }
6459
6460 static void test_reserve_memory_special_shm() {
6461 size_t lp = os::large_page_size();
6462 size_t ag = os::vm_allocation_granularity();
6463
6464 for (size_t size = ag; size < lp * 3; size += ag) {
6465 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) {
6466 test_reserve_memory_special_shm(size, alignment);
6467 }
6468 }
6469 }
6470
6471 static void test() {
6472 test_reserve_memory_special_huge_tlbfs();
6473 test_reserve_memory_special_shm();
6474 }
6475 };
6476
6477 void TestReserveMemorySpecial_test() {
6478 TestReserveMemorySpecial::test();
6479 }
6480
6481 #endif