1 /*
2 * Copyright (c) 1999, 2015, 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 // if RUSAGE_THREAD for getrusage() has not been defined, do it here. The code calling
108 // getrusage() is prepared to handle the associated failure.
109 #ifndef RUSAGE_THREAD
110 #define RUSAGE_THREAD (1) /* only the calling thread */
111 #endif
112
113 #define MAX_PATH (2 * K)
114
115 #define MAX_SECS 100000000
116
117 // for timer info max values which include all bits
118 #define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF)
119
120 #define LARGEPAGES_BIT (1 << 6)
121 ////////////////////////////////////////////////////////////////////////////////
122 // global variables
123 julong os::Linux::_physical_memory = 0;
124
125 address os::Linux::_initial_thread_stack_bottom = NULL;
126 uintptr_t os::Linux::_initial_thread_stack_size = 0;
127
128 int (*os::Linux::_clock_gettime)(clockid_t, struct timespec *) = NULL;
129 int (*os::Linux::_pthread_getcpuclockid)(pthread_t, clockid_t *) = NULL;
130 Mutex* os::Linux::_createThread_lock = NULL;
131 pthread_t os::Linux::_main_thread;
132 int os::Linux::_page_size = -1;
133 const int os::Linux::_vm_default_page_size = (8 * K);
134 bool os::Linux::_is_floating_stack = false;
135 bool os::Linux::_is_NPTL = false;
136 bool os::Linux::_supports_fast_thread_cpu_time = false;
137 const char * os::Linux::_glibc_version = NULL;
138 const char * os::Linux::_libpthread_version = NULL;
139 pthread_condattr_t os::Linux::_condattr[1];
140
141 static jlong initial_time_count=0;
142
143 static int clock_tics_per_sec = 100;
144
145 // For diagnostics to print a message once. see run_periodic_checks
146 static sigset_t check_signal_done;
147 static bool check_signals = true;
148
149 static pid_t _initial_pid = 0;
150
151 /* Signal number used to suspend/resume a thread */
152
153 /* do not use any signal number less than SIGSEGV, see 4355769 */
154 static int SR_signum = SIGUSR2;
155 sigset_t SR_sigset;
156
157 /* Used to protect dlsym() calls */
158 static pthread_mutex_t dl_mutex;
159
160 // Declarations
161 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time);
162
163 // utility functions
164
165 static int SR_initialize();
166
167 julong os::available_memory() {
168 return Linux::available_memory();
169 }
170
171 julong os::Linux::available_memory() {
172 // values in struct sysinfo are "unsigned long"
173 struct sysinfo si;
174 sysinfo(&si);
175
176 return (julong)si.freeram * si.mem_unit;
177 }
178
179 julong os::physical_memory() {
180 return Linux::physical_memory();
181 }
182
183 ////////////////////////////////////////////////////////////////////////////////
184 // environment support
185
186 bool os::getenv(const char* name, char* buf, int len) {
187 const char* val = ::getenv(name);
188 if (val != NULL && strlen(val) < (size_t)len) {
189 strcpy(buf, val);
190 return true;
191 }
192 if (len > 0) buf[0] = 0; // return a null string
193 return false;
194 }
195
196
197 // Return true if user is running as root.
198
199 bool os::have_special_privileges() {
200 static bool init = false;
201 static bool privileges = false;
202 if (!init) {
203 privileges = (getuid() != geteuid()) || (getgid() != getegid());
204 init = true;
205 }
206 return privileges;
207 }
208
209
210 #ifndef SYS_gettid
211 // i386: 224, ia64: 1105, amd64: 186, sparc 143
212 #ifdef __ia64__
213 #define SYS_gettid 1105
214 #else
215 #ifdef __i386__
216 #define SYS_gettid 224
217 #else
218 #ifdef __amd64__
219 #define SYS_gettid 186
220 #else
221 #ifdef __sparc__
222 #define SYS_gettid 143
223 #else
224 #error define gettid for the arch
225 #endif
226 #endif
227 #endif
228 #endif
229 #endif
230
231 // Cpu architecture string
232 static char cpu_arch[] = HOTSPOT_LIB_ARCH;
233
234 // pid_t gettid()
235 //
236 // Returns the kernel thread id of the currently running thread. Kernel
237 // thread id is used to access /proc.
238 //
239 // (Note that getpid() on LinuxThreads returns kernel thread id too; but
240 // on NPTL, it returns the same pid for all threads, as required by POSIX.)
241 //
242 pid_t os::Linux::gettid() {
243 int rslt = syscall(SYS_gettid);
244 if (rslt == -1) {
245 // old kernel, no NPTL support
246 return getpid();
247 } else {
248 return (pid_t)rslt;
249 }
250 }
251
252 // Most versions of linux have a bug where the number of processors are
253 // determined by looking at the /proc file system. In a chroot environment,
254 // the system call returns 1. This causes the VM to act as if it is
255 // a single processor and elide locking (see is_MP() call).
256 static bool unsafe_chroot_detected = false;
257 static const char *unstable_chroot_error = "/proc file system not found.\n"
258 "Java may be unstable running multithreaded in a chroot "
259 "environment on Linux when /proc filesystem is not mounted.";
260
261 void os::Linux::initialize_system_info() {
262 set_processor_count(sysconf(_SC_NPROCESSORS_CONF));
263 if (processor_count() == 1) {
264 pid_t pid = os::Linux::gettid();
265 char fname[32];
266 jio_snprintf(fname, sizeof(fname), "/proc/%d", pid);
267 FILE *fp = fopen(fname, "r");
268 if (fp == NULL) {
269 unsafe_chroot_detected = true;
270 } else {
271 fclose(fp);
272 }
273 }
274 _physical_memory = (julong)sysconf(_SC_PHYS_PAGES) * (julong)sysconf(_SC_PAGESIZE);
275 assert(processor_count() > 0, "linux error");
276 }
277
278 void os::init_system_properties_values() {
279 // The next steps are taken in the product version:
280 //
281 // Obtain the JAVA_HOME value from the location of libjvm.so.
282 // This library should be located at:
283 // <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm.so.
284 //
285 // If "/jre/lib/" appears at the right place in the path, then we
286 // assume libjvm.so is installed in a JDK and we use this path.
287 //
288 // Otherwise exit with message: "Could not create the Java virtual machine."
289 //
290 // The following extra steps are taken in the debugging version:
291 //
292 // If "/jre/lib/" does NOT appear at the right place in the path
293 // instead of exit check for $JAVA_HOME environment variable.
294 //
295 // If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>,
296 // then we append a fake suffix "hotspot/libjvm.so" to this path so
297 // it looks like libjvm.so is installed there
298 // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm.so.
299 //
300 // Otherwise exit.
301 //
302 // Important note: if the location of libjvm.so changes this
303 // code needs to be changed accordingly.
304
305 // See ld(1):
306 // The linker uses the following search paths to locate required
307 // shared libraries:
308 // 1: ...
309 // ...
310 // 7: The default directories, normally /lib and /usr/lib.
311 #if defined(AMD64) || defined(_LP64) && (defined(SPARC) || defined(PPC) || defined(S390))
312 #define DEFAULT_LIBPATH "/usr/lib64:/lib64:/lib:/usr/lib"
313 #else
314 #define DEFAULT_LIBPATH "/lib:/usr/lib"
315 #endif
316
317 // Base path of extensions installed on the system.
318 #define SYS_EXT_DIR "/usr/java/packages"
319 #define EXTENSIONS_DIR "/lib/ext"
320 #define ENDORSED_DIR "/lib/endorsed"
321
322 // Buffer that fits several sprintfs.
323 // Note that the space for the colon and the trailing null are provided
324 // by the nulls included by the sizeof operator.
325 const size_t bufsize =
326 MAX3((size_t)MAXPATHLEN, // For dll_dir & friends.
327 (size_t)MAXPATHLEN + sizeof(EXTENSIONS_DIR) + sizeof(SYS_EXT_DIR) + sizeof(EXTENSIONS_DIR), // extensions dir
328 (size_t)MAXPATHLEN + sizeof(ENDORSED_DIR)); // endorsed dir
329 char *buf = (char *)NEW_C_HEAP_ARRAY(char, bufsize, mtInternal);
330
331 // sysclasspath, java_home, dll_dir
332 {
333 char *pslash;
334 os::jvm_path(buf, bufsize);
335
336 // Found the full path to libjvm.so.
337 // Now cut the path to <java_home>/jre if we can.
338 *(strrchr(buf, '/')) = '\0'; // Get rid of /libjvm.so.
339 pslash = strrchr(buf, '/');
340 if (pslash != NULL) {
341 *pslash = '\0'; // Get rid of /{client|server|hotspot}.
342 }
343 Arguments::set_dll_dir(buf);
344
345 if (pslash != NULL) {
346 pslash = strrchr(buf, '/');
347 if (pslash != NULL) {
348 *pslash = '\0'; // Get rid of /<arch>.
349 pslash = strrchr(buf, '/');
350 if (pslash != NULL) {
351 *pslash = '\0'; // Get rid of /lib.
352 }
353 }
354 }
355 Arguments::set_java_home(buf);
356 set_boot_path('/', ':');
357 }
358
359 // Where to look for native libraries.
360 //
361 // Note: Due to a legacy implementation, most of the library path
362 // is set in the launcher. This was to accomodate linking restrictions
363 // on legacy Linux implementations (which are no longer supported).
364 // Eventually, all the library path setting will be done here.
365 //
366 // However, to prevent the proliferation of improperly built native
367 // libraries, the new path component /usr/java/packages is added here.
368 // Eventually, all the library path setting will be done here.
369 {
370 // Get the user setting of LD_LIBRARY_PATH, and prepended it. It
371 // should always exist (until the legacy problem cited above is
372 // addressed).
373 const char *v = ::getenv("LD_LIBRARY_PATH");
374 const char *v_colon = ":";
375 if (v == NULL) { v = ""; v_colon = ""; }
376 // That's +1 for the colon and +1 for the trailing '\0'.
377 char *ld_library_path = (char *)NEW_C_HEAP_ARRAY(char,
378 strlen(v) + 1 +
379 sizeof(SYS_EXT_DIR) + sizeof("/lib/") + strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH) + 1,
380 mtInternal);
381 sprintf(ld_library_path, "%s%s" SYS_EXT_DIR "/lib/%s:" DEFAULT_LIBPATH, v, v_colon, cpu_arch);
382 Arguments::set_library_path(ld_library_path);
383 FREE_C_HEAP_ARRAY(char, ld_library_path, mtInternal);
384 }
385
386 // Extensions directories.
387 sprintf(buf, "%s" EXTENSIONS_DIR ":" SYS_EXT_DIR EXTENSIONS_DIR, Arguments::get_java_home());
388 Arguments::set_ext_dirs(buf);
389
390 // Endorsed standards default directory.
391 sprintf(buf, "%s" ENDORSED_DIR, Arguments::get_java_home());
392 Arguments::set_endorsed_dirs(buf);
393
394 FREE_C_HEAP_ARRAY(char, buf, mtInternal);
395
396 #undef DEFAULT_LIBPATH
397 #undef SYS_EXT_DIR
398 #undef EXTENSIONS_DIR
399 #undef ENDORSED_DIR
400 }
401
402 ////////////////////////////////////////////////////////////////////////////////
403 // breakpoint support
404
405 void os::breakpoint() {
406 BREAKPOINT;
407 }
408
409 extern "C" void breakpoint() {
410 // use debugger to set breakpoint here
411 }
412
413 ////////////////////////////////////////////////////////////////////////////////
414 // signal support
415
416 debug_only(static bool signal_sets_initialized = false);
417 static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs;
418
419 bool os::Linux::is_sig_ignored(int sig) {
420 struct sigaction oact;
421 sigaction(sig, (struct sigaction*)NULL, &oact);
422 void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*, oact.sa_sigaction)
423 : CAST_FROM_FN_PTR(void*, oact.sa_handler);
424 if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN))
425 return true;
426 else
427 return false;
428 }
429
430 void os::Linux::signal_sets_init() {
431 // Should also have an assertion stating we are still single-threaded.
432 assert(!signal_sets_initialized, "Already initialized");
433 // Fill in signals that are necessarily unblocked for all threads in
434 // the VM. Currently, we unblock the following signals:
435 // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden
436 // by -Xrs (=ReduceSignalUsage));
437 // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all
438 // other threads. The "ReduceSignalUsage" boolean tells us not to alter
439 // the dispositions or masks wrt these signals.
440 // Programs embedding the VM that want to use the above signals for their
441 // own purposes must, at this time, use the "-Xrs" option to prevent
442 // interference with shutdown hooks and BREAK_SIGNAL thread dumping.
443 // (See bug 4345157, and other related bugs).
444 // In reality, though, unblocking these signals is really a nop, since
445 // these signals are not blocked by default.
446 sigemptyset(&unblocked_sigs);
447 sigemptyset(&allowdebug_blocked_sigs);
448 sigaddset(&unblocked_sigs, SIGILL);
449 sigaddset(&unblocked_sigs, SIGSEGV);
450 sigaddset(&unblocked_sigs, SIGBUS);
451 sigaddset(&unblocked_sigs, SIGFPE);
452 #if defined(PPC64)
453 sigaddset(&unblocked_sigs, SIGTRAP);
454 #endif
455 sigaddset(&unblocked_sigs, SR_signum);
456
457 if (!ReduceSignalUsage) {
458 if (!os::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) {
459 sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL);
460 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL);
461 }
462 if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) {
463 sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL);
464 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL);
465 }
466 if (!os::Linux::is_sig_ignored(SHUTDOWN3_SIGNAL)) {
467 sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL);
468 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN3_SIGNAL);
469 }
470 }
471 // Fill in signals that are blocked by all but the VM thread.
472 sigemptyset(&vm_sigs);
473 if (!ReduceSignalUsage)
474 sigaddset(&vm_sigs, BREAK_SIGNAL);
475 debug_only(signal_sets_initialized = true);
476
477 }
478
479 // These are signals that are unblocked while a thread is running Java.
480 // (For some reason, they get blocked by default.)
481 sigset_t* os::Linux::unblocked_signals() {
482 assert(signal_sets_initialized, "Not initialized");
483 return &unblocked_sigs;
484 }
485
486 // These are the signals that are blocked while a (non-VM) thread is
487 // running Java. Only the VM thread handles these signals.
488 sigset_t* os::Linux::vm_signals() {
489 assert(signal_sets_initialized, "Not initialized");
490 return &vm_sigs;
491 }
492
493 // These are signals that are blocked during cond_wait to allow debugger in
494 sigset_t* os::Linux::allowdebug_blocked_signals() {
495 assert(signal_sets_initialized, "Not initialized");
496 return &allowdebug_blocked_sigs;
497 }
498
499 void os::Linux::hotspot_sigmask(Thread* thread) {
500
501 //Save caller's signal mask before setting VM signal mask
502 sigset_t caller_sigmask;
503 pthread_sigmask(SIG_BLOCK, NULL, &caller_sigmask);
504
505 OSThread* osthread = thread->osthread();
506 osthread->set_caller_sigmask(caller_sigmask);
507
508 pthread_sigmask(SIG_UNBLOCK, os::Linux::unblocked_signals(), NULL);
509
510 if (!ReduceSignalUsage) {
511 if (thread->is_VM_thread()) {
512 // Only the VM thread handles BREAK_SIGNAL ...
513 pthread_sigmask(SIG_UNBLOCK, vm_signals(), NULL);
514 } else {
515 // ... all other threads block BREAK_SIGNAL
516 pthread_sigmask(SIG_BLOCK, vm_signals(), NULL);
517 }
518 }
519 }
520
521 //////////////////////////////////////////////////////////////////////////////
522 // detecting pthread library
523
524 void os::Linux::libpthread_init() {
525 // Save glibc and pthread version strings. Note that _CS_GNU_LIBC_VERSION
526 // and _CS_GNU_LIBPTHREAD_VERSION are supported in glibc >= 2.3.2. Use a
527 // generic name for earlier versions.
528 // Define macros here so we can build HotSpot on old systems.
529 # ifndef _CS_GNU_LIBC_VERSION
530 # define _CS_GNU_LIBC_VERSION 2
531 # endif
532 # ifndef _CS_GNU_LIBPTHREAD_VERSION
533 # define _CS_GNU_LIBPTHREAD_VERSION 3
534 # endif
535
536 size_t n = confstr(_CS_GNU_LIBC_VERSION, NULL, 0);
537 if (n > 0) {
538 char *str = (char *)malloc(n, mtInternal);
539 confstr(_CS_GNU_LIBC_VERSION, str, n);
540 os::Linux::set_glibc_version(str);
541 } else {
542 // _CS_GNU_LIBC_VERSION is not supported, try gnu_get_libc_version()
543 static char _gnu_libc_version[32];
544 jio_snprintf(_gnu_libc_version, sizeof(_gnu_libc_version),
545 "glibc %s %s", gnu_get_libc_version(), gnu_get_libc_release());
546 os::Linux::set_glibc_version(_gnu_libc_version);
547 }
548
549 n = confstr(_CS_GNU_LIBPTHREAD_VERSION, NULL, 0);
550 if (n > 0) {
551 char *str = (char *)malloc(n, mtInternal);
552 confstr(_CS_GNU_LIBPTHREAD_VERSION, str, n);
553 // Vanilla RH-9 (glibc 2.3.2) has a bug that confstr() always tells
554 // us "NPTL-0.29" even we are running with LinuxThreads. Check if this
555 // is the case. LinuxThreads has a hard limit on max number of threads.
556 // So sysconf(_SC_THREAD_THREADS_MAX) will return a positive value.
557 // On the other hand, NPTL does not have such a limit, sysconf()
558 // will return -1 and errno is not changed. Check if it is really NPTL.
559 if (strcmp(os::Linux::glibc_version(), "glibc 2.3.2") == 0 &&
560 strstr(str, "NPTL") &&
561 sysconf(_SC_THREAD_THREADS_MAX) > 0) {
562 free(str);
563 os::Linux::set_libpthread_version("linuxthreads");
564 } else {
565 os::Linux::set_libpthread_version(str);
566 }
567 } else {
568 // glibc before 2.3.2 only has LinuxThreads.
569 os::Linux::set_libpthread_version("linuxthreads");
570 }
571
572 if (strstr(libpthread_version(), "NPTL")) {
573 os::Linux::set_is_NPTL();
574 } else {
575 os::Linux::set_is_LinuxThreads();
576 }
577
578 // LinuxThreads have two flavors: floating-stack mode, which allows variable
579 // stack size; and fixed-stack mode. NPTL is always floating-stack.
580 if (os::Linux::is_NPTL() || os::Linux::supports_variable_stack_size()) {
581 os::Linux::set_is_floating_stack();
582 }
583 }
584
585 /////////////////////////////////////////////////////////////////////////////
586 // thread stack
587
588 // Force Linux kernel to expand current thread stack. If "bottom" is close
589 // to the stack guard, caller should block all signals.
590 //
591 // MAP_GROWSDOWN:
592 // A special mmap() flag that is used to implement thread stacks. It tells
593 // kernel that the memory region should extend downwards when needed. This
594 // allows early versions of LinuxThreads to only mmap the first few pages
595 // when creating a new thread. Linux kernel will automatically expand thread
596 // stack as needed (on page faults).
597 //
598 // However, because the memory region of a MAP_GROWSDOWN stack can grow on
599 // demand, if a page fault happens outside an already mapped MAP_GROWSDOWN
600 // region, it's hard to tell if the fault is due to a legitimate stack
601 // access or because of reading/writing non-exist memory (e.g. buffer
602 // overrun). As a rule, if the fault happens below current stack pointer,
603 // Linux kernel does not expand stack, instead a SIGSEGV is sent to the
604 // application (see Linux kernel fault.c).
605 //
606 // This Linux feature can cause SIGSEGV when VM bangs thread stack for
607 // stack overflow detection.
608 //
609 // Newer version of LinuxThreads (since glibc-2.2, or, RH-7.x) and NPTL do
610 // not use this flag. However, the stack of initial thread is not created
611 // by pthread, it is still MAP_GROWSDOWN. Also it's possible (though
612 // unlikely) that user code can create a thread with MAP_GROWSDOWN stack
613 // and then attach the thread to JVM.
614 //
615 // To get around the problem and allow stack banging on Linux, we need to
616 // manually expand thread stack after receiving the SIGSEGV.
617 //
618 // There are two ways to expand thread stack to address "bottom", we used
619 // both of them in JVM before 1.5:
620 // 1. adjust stack pointer first so that it is below "bottom", and then
621 // touch "bottom"
622 // 2. mmap() the page in question
623 //
624 // Now alternate signal stack is gone, it's harder to use 2. For instance,
625 // if current sp is already near the lower end of page 101, and we need to
626 // call mmap() to map page 100, it is possible that part of the mmap() frame
627 // will be placed in page 100. When page 100 is mapped, it is zero-filled.
628 // That will destroy the mmap() frame and cause VM to crash.
629 //
630 // The following code works by adjusting sp first, then accessing the "bottom"
631 // page to force a page fault. Linux kernel will then automatically expand the
632 // stack mapping.
633 //
634 // _expand_stack_to() assumes its frame size is less than page size, which
635 // should always be true if the function is not inlined.
636
637 #if __GNUC__ < 3 // gcc 2.x does not support noinline attribute
638 #define NOINLINE
639 #else
640 #define NOINLINE __attribute__ ((noinline))
641 #endif
642
643 static void _expand_stack_to(address bottom) NOINLINE;
644
645 static void _expand_stack_to(address bottom) {
646 address sp;
647 size_t size;
648 volatile char *p;
649
650 // Adjust bottom to point to the largest address within the same page, it
651 // gives us a one-page buffer if alloca() allocates slightly more memory.
652 bottom = (address)align_size_down((uintptr_t)bottom, os::Linux::page_size());
653 bottom += os::Linux::page_size() - 1;
654
655 // sp might be slightly above current stack pointer; if that's the case, we
656 // will alloca() a little more space than necessary, which is OK. Don't use
657 // os::current_stack_pointer(), as its result can be slightly below current
658 // stack pointer, causing us to not alloca enough to reach "bottom".
659 sp = (address)&sp;
660
661 if (sp > bottom) {
662 size = sp - bottom;
663 p = (volatile char *)alloca(size);
664 assert(p != NULL && p <= (volatile char *)bottom, "alloca problem?");
665 p[0] = '\0';
666 }
667 }
668
669 bool os::Linux::manually_expand_stack(JavaThread * t, address addr) {
670 assert(t!=NULL, "just checking");
671 assert(t->osthread()->expanding_stack(), "expand should be set");
672 assert(t->stack_base() != NULL, "stack_base was not initialized");
673
674 if (addr < t->stack_base() && addr >= t->stack_yellow_zone_base()) {
675 sigset_t mask_all, old_sigset;
676 sigfillset(&mask_all);
677 pthread_sigmask(SIG_SETMASK, &mask_all, &old_sigset);
678 _expand_stack_to(addr);
679 pthread_sigmask(SIG_SETMASK, &old_sigset, NULL);
680 return true;
681 }
682 return false;
683 }
684
685 //////////////////////////////////////////////////////////////////////////////
686 // create new thread
687
688 static address highest_vm_reserved_address();
689
690 // check if it's safe to start a new thread
691 static bool _thread_safety_check(Thread* thread) {
692 if (os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack()) {
693 // Fixed stack LinuxThreads (SuSE Linux/x86, and some versions of Redhat)
694 // Heap is mmap'ed at lower end of memory space. Thread stacks are
695 // allocated (MAP_FIXED) from high address space. Every thread stack
696 // occupies a fixed size slot (usually 2Mbytes, but user can change
697 // it to other values if they rebuild LinuxThreads).
698 //
699 // Problem with MAP_FIXED is that mmap() can still succeed even part of
700 // the memory region has already been mmap'ed. That means if we have too
701 // many threads and/or very large heap, eventually thread stack will
702 // collide with heap.
703 //
704 // Here we try to prevent heap/stack collision by comparing current
705 // stack bottom with the highest address that has been mmap'ed by JVM
706 // plus a safety margin for memory maps created by native code.
707 //
708 // This feature can be disabled by setting ThreadSafetyMargin to 0
709 //
710 if (ThreadSafetyMargin > 0) {
711 address stack_bottom = os::current_stack_base() - os::current_stack_size();
712
713 // not safe if our stack extends below the safety margin
714 return stack_bottom - ThreadSafetyMargin >= highest_vm_reserved_address();
715 } else {
716 return true;
717 }
718 } else {
719 // Floating stack LinuxThreads or NPTL:
720 // Unlike fixed stack LinuxThreads, thread stacks are not MAP_FIXED. When
721 // there's not enough space left, pthread_create() will fail. If we come
722 // here, that means enough space has been reserved for stack.
723 return true;
724 }
725 }
726
727 // Thread start routine for all newly created threads
728 static void *java_start(Thread *thread) {
729 // Try to randomize the cache line index of hot stack frames.
730 // This helps when threads of the same stack traces evict each other's
731 // cache lines. The threads can be either from the same JVM instance, or
732 // from different JVM instances. The benefit is especially true for
733 // processors with hyperthreading technology.
734 static int counter = 0;
735 int pid = os::current_process_id();
736 alloca(((pid ^ counter++) & 7) * 128);
737
738 ThreadLocalStorage::set_thread(thread);
739
740 OSThread* osthread = thread->osthread();
741 Monitor* sync = osthread->startThread_lock();
742
743 // non floating stack LinuxThreads needs extra check, see above
744 if (!_thread_safety_check(thread)) {
745 // notify parent thread
746 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
747 osthread->set_state(ZOMBIE);
748 sync->notify_all();
749 return NULL;
750 }
751
752 // thread_id is kernel thread id (similar to Solaris LWP id)
753 osthread->set_thread_id(os::Linux::gettid());
754
755 if (UseNUMA) {
756 int lgrp_id = os::numa_get_group_id();
757 if (lgrp_id != -1) {
758 thread->set_lgrp_id(lgrp_id);
759 }
760 }
761 // initialize signal mask for this thread
762 os::Linux::hotspot_sigmask(thread);
763
764 // initialize floating point control register
765 os::Linux::init_thread_fpu_state();
766
767 // handshaking with parent thread
768 {
769 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
770
771 // notify parent thread
772 osthread->set_state(INITIALIZED);
773 sync->notify_all();
774
775 // wait until os::start_thread()
776 while (osthread->get_state() == INITIALIZED) {
777 sync->wait(Mutex::_no_safepoint_check_flag);
778 }
779 }
780
781 // call one more level start routine
782 thread->run();
783
784 return 0;
785 }
786
787 bool os::create_thread(Thread* thread, ThreadType thr_type, size_t stack_size) {
788 assert(thread->osthread() == NULL, "caller responsible");
789
790 // Allocate the OSThread object
791 OSThread* osthread = new OSThread(NULL, NULL);
792 if (osthread == NULL) {
793 return false;
794 }
795
796 // set the correct thread state
797 osthread->set_thread_type(thr_type);
798
799 // Initial state is ALLOCATED but not INITIALIZED
800 osthread->set_state(ALLOCATED);
801
802 thread->set_osthread(osthread);
803
804 // init thread attributes
805 pthread_attr_t attr;
806 pthread_attr_init(&attr);
807 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
808
809 // stack size
810 if (os::Linux::supports_variable_stack_size()) {
811 // calculate stack size if it's not specified by caller
812 if (stack_size == 0) {
813 stack_size = os::Linux::default_stack_size(thr_type);
814
815 switch (thr_type) {
816 case os::java_thread:
817 // Java threads use ThreadStackSize which default value can be
818 // changed with the flag -Xss
819 assert (JavaThread::stack_size_at_create() > 0, "this should be set");
820 stack_size = JavaThread::stack_size_at_create();
821 break;
822 case os::compiler_thread:
823 if (CompilerThreadStackSize > 0) {
824 stack_size = (size_t)(CompilerThreadStackSize * K);
825 break;
826 } // else fall through:
827 // use VMThreadStackSize if CompilerThreadStackSize is not defined
828 case os::vm_thread:
829 case os::pgc_thread:
830 case os::cgc_thread:
831 case os::watcher_thread:
832 if (VMThreadStackSize > 0) stack_size = (size_t)(VMThreadStackSize * K);
833 break;
834 }
835 }
836
837 stack_size = MAX2(stack_size, os::Linux::min_stack_allowed);
838 pthread_attr_setstacksize(&attr, stack_size);
839 } else {
840 // let pthread_create() pick the default value.
841 }
842
843 // glibc guard page
844 pthread_attr_setguardsize(&attr, os::Linux::default_guard_size(thr_type));
845
846 ThreadState state;
847
848 {
849 // Serialize thread creation if we are running with fixed stack LinuxThreads
850 bool lock = os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack();
851 if (lock) {
852 os::Linux::createThread_lock()->lock_without_safepoint_check();
853 }
854
855 pthread_t tid;
856 int ret = pthread_create(&tid, &attr, (void* (*)(void*)) java_start, thread);
857
858 pthread_attr_destroy(&attr);
859
860 if (ret != 0) {
861 if (PrintMiscellaneous && (Verbose || WizardMode)) {
862 perror("pthread_create()");
863 }
864 // Need to clean up stuff we've allocated so far
865 thread->set_osthread(NULL);
866 delete osthread;
867 if (lock) os::Linux::createThread_lock()->unlock();
868 return false;
869 }
870
871 // Store pthread info into the OSThread
872 osthread->set_pthread_id(tid);
873
874 // Wait until child thread is either initialized or aborted
875 {
876 Monitor* sync_with_child = osthread->startThread_lock();
877 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
878 while ((state = osthread->get_state()) == ALLOCATED) {
879 sync_with_child->wait(Mutex::_no_safepoint_check_flag);
880 }
881 }
882
883 if (lock) {
884 os::Linux::createThread_lock()->unlock();
885 }
886 }
887
888 // Aborted due to thread limit being reached
889 if (state == ZOMBIE) {
890 thread->set_osthread(NULL);
891 delete osthread;
892 return false;
893 }
894
895 // The thread is returned suspended (in state INITIALIZED),
896 // and is started higher up in the call chain
897 assert(state == INITIALIZED, "race condition");
898 return true;
899 }
900
901 /////////////////////////////////////////////////////////////////////////////
902 // attach existing thread
903
904 // bootstrap the main thread
905 bool os::create_main_thread(JavaThread* thread) {
906 assert(os::Linux::_main_thread == pthread_self(), "should be called inside main thread");
907 return create_attached_thread(thread);
908 }
909
910 bool os::create_attached_thread(JavaThread* thread) {
911 #ifdef ASSERT
912 thread->verify_not_published();
913 #endif
914
915 // Allocate the OSThread object
916 OSThread* osthread = new OSThread(NULL, NULL);
917
918 if (osthread == NULL) {
919 return false;
920 }
921
922 // Store pthread info into the OSThread
923 osthread->set_thread_id(os::Linux::gettid());
924 osthread->set_pthread_id(::pthread_self());
925
926 // initialize floating point control register
927 os::Linux::init_thread_fpu_state();
928
929 // Initial thread state is RUNNABLE
930 osthread->set_state(RUNNABLE);
931
932 thread->set_osthread(osthread);
933
934 if (UseNUMA) {
935 int lgrp_id = os::numa_get_group_id();
936 if (lgrp_id != -1) {
937 thread->set_lgrp_id(lgrp_id);
938 }
939 }
940
941 if (os::Linux::is_initial_thread()) {
942 // If current thread is initial thread, its stack is mapped on demand,
943 // see notes about MAP_GROWSDOWN. Here we try to force kernel to map
944 // the entire stack region to avoid SEGV in stack banging.
945 // It is also useful to get around the heap-stack-gap problem on SuSE
946 // kernel (see 4821821 for details). We first expand stack to the top
947 // of yellow zone, then enable stack yellow zone (order is significant,
948 // enabling yellow zone first will crash JVM on SuSE Linux), so there
949 // is no gap between the last two virtual memory regions.
950
951 JavaThread *jt = (JavaThread *)thread;
952 address addr = jt->stack_yellow_zone_base();
953 assert(addr != NULL, "initialization problem?");
954 assert(jt->stack_available(addr) > 0, "stack guard should not be enabled");
955
956 osthread->set_expanding_stack();
957 os::Linux::manually_expand_stack(jt, addr);
958 osthread->clear_expanding_stack();
959 }
960
961 // initialize signal mask for this thread
962 // and save the caller's signal mask
963 os::Linux::hotspot_sigmask(thread);
964
965 return true;
966 }
967
968 void os::pd_start_thread(Thread* thread) {
969 OSThread * osthread = thread->osthread();
970 assert(osthread->get_state() != INITIALIZED, "just checking");
971 Monitor* sync_with_child = osthread->startThread_lock();
972 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
973 sync_with_child->notify();
974 }
975
976 // Free Linux resources related to the OSThread
977 void os::free_thread(OSThread* osthread) {
978 assert(osthread != NULL, "osthread not set");
979
980 if (Thread::current()->osthread() == osthread) {
981 // Restore caller's signal mask
982 sigset_t sigmask = osthread->caller_sigmask();
983 pthread_sigmask(SIG_SETMASK, &sigmask, NULL);
984 }
985
986 delete osthread;
987 }
988
989 //////////////////////////////////////////////////////////////////////////////
990 // thread local storage
991
992 // Restore the thread pointer if the destructor is called. This is in case
993 // someone from JNI code sets up a destructor with pthread_key_create to run
994 // detachCurrentThread on thread death. Unless we restore the thread pointer we
995 // will hang or crash. When detachCurrentThread is called the key will be set
996 // to null and we will not be called again. If detachCurrentThread is never
997 // called we could loop forever depending on the pthread implementation.
998 static void restore_thread_pointer(void* p) {
999 Thread* thread = (Thread*) p;
1000 os::thread_local_storage_at_put(ThreadLocalStorage::thread_index(), thread);
1001 }
1002
1003 int os::allocate_thread_local_storage() {
1004 pthread_key_t key;
1005 int rslt = pthread_key_create(&key, restore_thread_pointer);
1006 assert(rslt == 0, "cannot allocate thread local storage");
1007 return (int)key;
1008 }
1009
1010 // Note: This is currently not used by VM, as we don't destroy TLS key
1011 // on VM exit.
1012 void os::free_thread_local_storage(int index) {
1013 int rslt = pthread_key_delete((pthread_key_t)index);
1014 assert(rslt == 0, "invalid index");
1015 }
1016
1017 void os::thread_local_storage_at_put(int index, void* value) {
1018 int rslt = pthread_setspecific((pthread_key_t)index, value);
1019 assert(rslt == 0, "pthread_setspecific failed");
1020 }
1021
1022 extern "C" Thread* get_thread() {
1023 return ThreadLocalStorage::thread();
1024 }
1025
1026 //////////////////////////////////////////////////////////////////////////////
1027 // initial thread
1028
1029 // Check if current thread is the initial thread, similar to Solaris thr_main.
1030 bool os::Linux::is_initial_thread(void) {
1031 char dummy;
1032 // If called before init complete, thread stack bottom will be null.
1033 // Can be called if fatal error occurs before initialization.
1034 if (initial_thread_stack_bottom() == NULL) return false;
1035 assert(initial_thread_stack_bottom() != NULL &&
1036 initial_thread_stack_size() != 0,
1037 "os::init did not locate initial thread's stack region");
1038 if ((address)&dummy >= initial_thread_stack_bottom() &&
1039 (address)&dummy < initial_thread_stack_bottom() + initial_thread_stack_size())
1040 return true;
1041 else return false;
1042 }
1043
1044 // Find the virtual memory area that contains addr
1045 static bool find_vma(address addr, address* vma_low, address* vma_high) {
1046 FILE *fp = fopen("/proc/self/maps", "r");
1047 if (fp) {
1048 address low, high;
1049 while (!feof(fp)) {
1050 if (fscanf(fp, "%p-%p", &low, &high) == 2) {
1051 if (low <= addr && addr < high) {
1052 if (vma_low) *vma_low = low;
1053 if (vma_high) *vma_high = high;
1054 fclose (fp);
1055 return true;
1056 }
1057 }
1058 for (;;) {
1059 int ch = fgetc(fp);
1060 if (ch == EOF || ch == (int)'\n') break;
1061 }
1062 }
1063 fclose(fp);
1064 }
1065 return false;
1066 }
1067
1068 // Locate initial thread stack. This special handling of initial thread stack
1069 // is needed because pthread_getattr_np() on most (all?) Linux distros returns
1070 // bogus value for initial thread.
1071 void os::Linux::capture_initial_stack(size_t max_size) {
1072 // stack size is the easy part, get it from RLIMIT_STACK
1073 size_t stack_size;
1074 struct rlimit rlim;
1075 getrlimit(RLIMIT_STACK, &rlim);
1076 stack_size = rlim.rlim_cur;
1077
1078 // 6308388: a bug in ld.so will relocate its own .data section to the
1079 // lower end of primordial stack; reduce ulimit -s value a little bit
1080 // so we won't install guard page on ld.so's data section.
1081 stack_size -= 2 * page_size();
1082
1083 // 4441425: avoid crash with "unlimited" stack size on SuSE 7.1 or Redhat
1084 // 7.1, in both cases we will get 2G in return value.
1085 // 4466587: glibc 2.2.x compiled w/o "--enable-kernel=2.4.0" (RH 7.0,
1086 // SuSE 7.2, Debian) can not handle alternate signal stack correctly
1087 // for initial thread if its stack size exceeds 6M. Cap it at 2M,
1088 // in case other parts in glibc still assumes 2M max stack size.
1089 // FIXME: alt signal stack is gone, maybe we can relax this constraint?
1090 // Problem still exists RH7.2 (IA64 anyway) but 2MB is a little small
1091 if (stack_size > 2 * K * K IA64_ONLY(*2))
1092 stack_size = 2 * K * K IA64_ONLY(*2);
1093 // Try to figure out where the stack base (top) is. This is harder.
1094 //
1095 // When an application is started, glibc saves the initial stack pointer in
1096 // a global variable "__libc_stack_end", which is then used by system
1097 // libraries. __libc_stack_end should be pretty close to stack top. The
1098 // variable is available since the very early days. However, because it is
1099 // a private interface, it could disappear in the future.
1100 //
1101 // Linux kernel saves start_stack information in /proc/<pid>/stat. Similar
1102 // to __libc_stack_end, it is very close to stack top, but isn't the real
1103 // stack top. Note that /proc may not exist if VM is running as a chroot
1104 // program, so reading /proc/<pid>/stat could fail. Also the contents of
1105 // /proc/<pid>/stat could change in the future (though unlikely).
1106 //
1107 // We try __libc_stack_end first. If that doesn't work, look for
1108 // /proc/<pid>/stat. If neither of them works, we use current stack pointer
1109 // as a hint, which should work well in most cases.
1110
1111 uintptr_t stack_start;
1112
1113 // try __libc_stack_end first
1114 uintptr_t *p = (uintptr_t *)dlsym(RTLD_DEFAULT, "__libc_stack_end");
1115 if (p && *p) {
1116 stack_start = *p;
1117 } else {
1118 // see if we can get the start_stack field from /proc/self/stat
1119 FILE *fp;
1120 int pid;
1121 char state;
1122 int ppid;
1123 int pgrp;
1124 int session;
1125 int nr;
1126 int tpgrp;
1127 unsigned long flags;
1128 unsigned long minflt;
1129 unsigned long cminflt;
1130 unsigned long majflt;
1131 unsigned long cmajflt;
1132 unsigned long utime;
1133 unsigned long stime;
1134 long cutime;
1135 long cstime;
1136 long prio;
1137 long nice;
1138 long junk;
1139 long it_real;
1140 uintptr_t start;
1141 uintptr_t vsize;
1142 intptr_t rss;
1143 uintptr_t rsslim;
1144 uintptr_t scodes;
1145 uintptr_t ecode;
1146 int i;
1147
1148 // Figure what the primordial thread stack base is. Code is inspired
1149 // by email from Hans Boehm. /proc/self/stat begins with current pid,
1150 // followed by command name surrounded by parentheses, state, etc.
1151 char stat[2048];
1152 int statlen;
1153
1154 fp = fopen("/proc/self/stat", "r");
1155 if (fp) {
1156 statlen = fread(stat, 1, 2047, fp);
1157 stat[statlen] = '\0';
1158 fclose(fp);
1159
1160 // Skip pid and the command string. Note that we could be dealing with
1161 // weird command names, e.g. user could decide to rename java launcher
1162 // to "java 1.4.2 :)", then the stat file would look like
1163 // 1234 (java 1.4.2 :)) R ... ...
1164 // We don't really need to know the command string, just find the last
1165 // occurrence of ")" and then start parsing from there. See bug 4726580.
1166 char * s = strrchr(stat, ')');
1167
1168 i = 0;
1169 if (s) {
1170 // Skip blank chars
1171 do s++; while (isspace(*s));
1172
1173 #define _UFM UINTX_FORMAT
1174 #define _DFM INTX_FORMAT
1175
1176 /* 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 */
1177 /* 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 */
1178 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,
1179 &state, /* 3 %c */
1180 &ppid, /* 4 %d */
1181 &pgrp, /* 5 %d */
1182 &session, /* 6 %d */
1183 &nr, /* 7 %d */
1184 &tpgrp, /* 8 %d */
1185 &flags, /* 9 %lu */
1186 &minflt, /* 10 %lu */
1187 &cminflt, /* 11 %lu */
1188 &majflt, /* 12 %lu */
1189 &cmajflt, /* 13 %lu */
1190 &utime, /* 14 %lu */
1191 &stime, /* 15 %lu */
1192 &cutime, /* 16 %ld */
1193 &cstime, /* 17 %ld */
1194 &prio, /* 18 %ld */
1195 &nice, /* 19 %ld */
1196 &junk, /* 20 %ld */
1197 &it_real, /* 21 %ld */
1198 &start, /* 22 UINTX_FORMAT */
1199 &vsize, /* 23 UINTX_FORMAT */
1200 &rss, /* 24 INTX_FORMAT */
1201 &rsslim, /* 25 UINTX_FORMAT */
1202 &scodes, /* 26 UINTX_FORMAT */
1203 &ecode, /* 27 UINTX_FORMAT */
1204 &stack_start); /* 28 UINTX_FORMAT */
1205 }
1206
1207 #undef _UFM
1208 #undef _DFM
1209
1210 if (i != 28 - 2) {
1211 assert(false, "Bad conversion from /proc/self/stat");
1212 // product mode - assume we are the initial thread, good luck in the
1213 // embedded case.
1214 warning("Can't detect initial thread stack location - bad conversion");
1215 stack_start = (uintptr_t) &rlim;
1216 }
1217 } else {
1218 // For some reason we can't open /proc/self/stat (for example, running on
1219 // FreeBSD with a Linux emulator, or inside chroot), this should work for
1220 // most cases, so don't abort:
1221 warning("Can't detect initial thread stack location - no /proc/self/stat");
1222 stack_start = (uintptr_t) &rlim;
1223 }
1224 }
1225
1226 // Now we have a pointer (stack_start) very close to the stack top, the
1227 // next thing to do is to figure out the exact location of stack top. We
1228 // can find out the virtual memory area that contains stack_start by
1229 // reading /proc/self/maps, it should be the last vma in /proc/self/maps,
1230 // and its upper limit is the real stack top. (again, this would fail if
1231 // running inside chroot, because /proc may not exist.)
1232
1233 uintptr_t stack_top;
1234 address low, high;
1235 if (find_vma((address)stack_start, &low, &high)) {
1236 // success, "high" is the true stack top. (ignore "low", because initial
1237 // thread stack grows on demand, its real bottom is high - RLIMIT_STACK.)
1238 stack_top = (uintptr_t)high;
1239 } else {
1240 // failed, likely because /proc/self/maps does not exist
1241 warning("Can't detect initial thread stack location - find_vma failed");
1242 // best effort: stack_start is normally within a few pages below the real
1243 // stack top, use it as stack top, and reduce stack size so we won't put
1244 // guard page outside stack.
1245 stack_top = stack_start;
1246 stack_size -= 16 * page_size();
1247 }
1248
1249 // stack_top could be partially down the page so align it
1250 stack_top = align_size_up(stack_top, page_size());
1251
1252 if (max_size && stack_size > max_size) {
1253 _initial_thread_stack_size = max_size;
1254 } else {
1255 _initial_thread_stack_size = stack_size;
1256 }
1257
1258 _initial_thread_stack_size = align_size_down(_initial_thread_stack_size, page_size());
1259 _initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size;
1260 }
1261
1262 ////////////////////////////////////////////////////////////////////////////////
1263 // time support
1264
1265 // Time since start-up in seconds to a fine granularity.
1266 // Used by VMSelfDestructTimer and the MemProfiler.
1267 double os::elapsedTime() {
1268
1269 return ((double)os::elapsed_counter()) / os::elapsed_frequency(); // nanosecond resolution
1270 }
1271
1272 jlong os::elapsed_counter() {
1273 return javaTimeNanos() - initial_time_count;
1274 }
1275
1276 jlong os::elapsed_frequency() {
1277 return NANOSECS_PER_SEC; // nanosecond resolution
1278 }
1279
1280 bool os::supports_vtime() { return true; }
1281 bool os::enable_vtime() { return false; }
1282 bool os::vtime_enabled() { return false; }
1283
1284 double os::elapsedVTime() {
1285 struct rusage usage;
1286 int retval = getrusage(RUSAGE_THREAD, &usage);
1287 if (retval == 0) {
1288 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);
1289 } else {
1290 // better than nothing, but not much
1291 return elapsedTime();
1292 }
1293 }
1294
1295 jlong os::javaTimeMillis() {
1296 timeval time;
1297 int status = gettimeofday(&time, NULL);
1298 assert(status != -1, "linux error");
1299 return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000);
1300 }
1301
1302 #ifndef CLOCK_MONOTONIC
1303 #define CLOCK_MONOTONIC (1)
1304 #endif
1305
1306 void os::Linux::clock_init() {
1307 // we do dlopen's in this particular order due to bug in linux
1308 // dynamical loader (see 6348968) leading to crash on exit
1309 void* handle = dlopen("librt.so.1", RTLD_LAZY);
1310 if (handle == NULL) {
1311 handle = dlopen("librt.so", RTLD_LAZY);
1312 }
1313
1314 if (handle) {
1315 int (*clock_getres_func)(clockid_t, struct timespec*) =
1316 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres");
1317 int (*clock_gettime_func)(clockid_t, struct timespec*) =
1318 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime");
1319 if (clock_getres_func && clock_gettime_func) {
1320 // See if monotonic clock is supported by the kernel. Note that some
1321 // early implementations simply return kernel jiffies (updated every
1322 // 1/100 or 1/1000 second). It would be bad to use such a low res clock
1323 // for nano time (though the monotonic property is still nice to have).
1324 // It's fixed in newer kernels, however clock_getres() still returns
1325 // 1/HZ. We check if clock_getres() works, but will ignore its reported
1326 // resolution for now. Hopefully as people move to new kernels, this
1327 // won't be a problem.
1328 struct timespec res;
1329 struct timespec tp;
1330 if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 &&
1331 clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) {
1332 // yes, monotonic clock is supported
1333 _clock_gettime = clock_gettime_func;
1334 return;
1335 } else {
1336 // close librt if there is no monotonic clock
1337 dlclose(handle);
1338 }
1339 }
1340 }
1341 warning("No monotonic clock was available - timed services may " \
1342 "be adversely affected if the time-of-day clock changes");
1343 }
1344
1345 #ifndef SYS_clock_getres
1346
1347 #if defined(IA32) || defined(AMD64)
1348 #define SYS_clock_getres IA32_ONLY(266) AMD64_ONLY(229)
1349 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y)
1350 #else
1351 #warning "SYS_clock_getres not defined for this platform, disabling fast_thread_cpu_time"
1352 #define sys_clock_getres(x,y) -1
1353 #endif
1354
1355 #else
1356 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y)
1357 #endif
1358
1359 void os::Linux::fast_thread_clock_init() {
1360 if (!UseLinuxPosixThreadCPUClocks) {
1361 return;
1362 }
1363 clockid_t clockid;
1364 struct timespec tp;
1365 int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) =
1366 (int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid");
1367
1368 // Switch to using fast clocks for thread cpu time if
1369 // the sys_clock_getres() returns 0 error code.
1370 // Note, that some kernels may support the current thread
1371 // clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks
1372 // returned by the pthread_getcpuclockid().
1373 // If the fast Posix clocks are supported then the sys_clock_getres()
1374 // must return at least tp.tv_sec == 0 which means a resolution
1375 // better than 1 sec. This is extra check for reliability.
1376
1377 if(pthread_getcpuclockid_func &&
1378 pthread_getcpuclockid_func(_main_thread, &clockid) == 0 &&
1379 sys_clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) {
1380
1381 _supports_fast_thread_cpu_time = true;
1382 _pthread_getcpuclockid = pthread_getcpuclockid_func;
1383 }
1384 }
1385
1386 jlong os::javaTimeNanos() {
1387 if (Linux::supports_monotonic_clock()) {
1388 struct timespec tp;
1389 int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp);
1390 assert(status == 0, "gettime error");
1391 jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec);
1392 return result;
1393 } else {
1394 timeval time;
1395 int status = gettimeofday(&time, NULL);
1396 assert(status != -1, "linux error");
1397 jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec);
1398 return 1000 * usecs;
1399 }
1400 }
1401
1402 void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) {
1403 if (Linux::supports_monotonic_clock()) {
1404 info_ptr->max_value = ALL_64_BITS;
1405
1406 // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past
1407 info_ptr->may_skip_backward = false; // not subject to resetting or drifting
1408 info_ptr->may_skip_forward = false; // not subject to resetting or drifting
1409 } else {
1410 // gettimeofday - based on time in seconds since the Epoch thus does not wrap
1411 info_ptr->max_value = ALL_64_BITS;
1412
1413 // gettimeofday is a real time clock so it skips
1414 info_ptr->may_skip_backward = true;
1415 info_ptr->may_skip_forward = true;
1416 }
1417
1418 info_ptr->kind = JVMTI_TIMER_ELAPSED; // elapsed not CPU time
1419 }
1420
1421 // Return the real, user, and system times in seconds from an
1422 // arbitrary fixed point in the past.
1423 bool os::getTimesSecs(double* process_real_time,
1424 double* process_user_time,
1425 double* process_system_time) {
1426 struct tms ticks;
1427 clock_t real_ticks = times(&ticks);
1428
1429 if (real_ticks == (clock_t) (-1)) {
1430 return false;
1431 } else {
1432 double ticks_per_second = (double) clock_tics_per_sec;
1433 *process_user_time = ((double) ticks.tms_utime) / ticks_per_second;
1434 *process_system_time = ((double) ticks.tms_stime) / ticks_per_second;
1435 *process_real_time = ((double) real_ticks) / ticks_per_second;
1436
1437 return true;
1438 }
1439 }
1440
1441
1442 char * os::local_time_string(char *buf, size_t buflen) {
1443 struct tm t;
1444 time_t long_time;
1445 time(&long_time);
1446 localtime_r(&long_time, &t);
1447 jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d",
1448 t.tm_year + 1900, t.tm_mon + 1, t.tm_mday,
1449 t.tm_hour, t.tm_min, t.tm_sec);
1450 return buf;
1451 }
1452
1453 struct tm* os::localtime_pd(const time_t* clock, struct tm* res) {
1454 return localtime_r(clock, res);
1455 }
1456
1457 ////////////////////////////////////////////////////////////////////////////////
1458 // runtime exit support
1459
1460 // Note: os::shutdown() might be called very early during initialization, or
1461 // called from signal handler. Before adding something to os::shutdown(), make
1462 // sure it is async-safe and can handle partially initialized VM.
1463 void os::shutdown() {
1464
1465 // allow PerfMemory to attempt cleanup of any persistent resources
1466 perfMemory_exit();
1467
1468 // needs to remove object in file system
1469 AttachListener::abort();
1470
1471 // flush buffered output, finish log files
1472 ostream_abort();
1473
1474 // Check for abort hook
1475 abort_hook_t abort_hook = Arguments::abort_hook();
1476 if (abort_hook != NULL) {
1477 abort_hook();
1478 }
1479
1480 }
1481
1482 // Note: os::abort() might be called very early during initialization, or
1483 // called from signal handler. Before adding something to os::abort(), make
1484 // sure it is async-safe and can handle partially initialized VM.
1485 void os::abort(bool dump_core) {
1486 os::shutdown();
1487 if (dump_core) {
1488 #ifndef PRODUCT
1489 fdStream out(defaultStream::output_fd());
1490 out.print_raw("Current thread is ");
1491 char buf[16];
1492 jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id());
1493 out.print_raw_cr(buf);
1494 out.print_raw_cr("Dumping core ...");
1495 #endif
1496 ::abort(); // dump core
1497 }
1498
1499 ::exit(1);
1500 }
1501
1502 // Die immediately, no exit hook, no abort hook, no cleanup.
1503 void os::die() {
1504 // _exit() on LinuxThreads only kills current thread
1505 ::abort();
1506 }
1507
1508
1509 // This method is a copy of JDK's sysGetLastErrorString
1510 // from src/solaris/hpi/src/system_md.c
1511
1512 size_t os::lasterror(char *buf, size_t len) {
1513
1514 if (errno == 0) return 0;
1515
1516 const char *s = ::strerror(errno);
1517 size_t n = ::strlen(s);
1518 if (n >= len) {
1519 n = len - 1;
1520 }
1521 ::strncpy(buf, s, n);
1522 buf[n] = '\0';
1523 return n;
1524 }
1525
1526 intx os::current_thread_id() { return (intx)pthread_self(); }
1527 int os::current_process_id() {
1528
1529 // Under the old linux thread library, linux gives each thread
1530 // its own process id. Because of this each thread will return
1531 // a different pid if this method were to return the result
1532 // of getpid(2). Linux provides no api that returns the pid
1533 // of the launcher thread for the vm. This implementation
1534 // returns a unique pid, the pid of the launcher thread
1535 // that starts the vm 'process'.
1536
1537 // Under the NPTL, getpid() returns the same pid as the
1538 // launcher thread rather than a unique pid per thread.
1539 // Use gettid() if you want the old pre NPTL behaviour.
1540
1541 // if you are looking for the result of a call to getpid() that
1542 // returns a unique pid for the calling thread, then look at the
1543 // OSThread::thread_id() method in osThread_linux.hpp file
1544
1545 return (int)(_initial_pid ? _initial_pid : getpid());
1546 }
1547
1548 // DLL functions
1549
1550 const char* os::dll_file_extension() { return ".so"; }
1551
1552 // This must be hard coded because it's the system's temporary
1553 // directory not the java application's temp directory, ala java.io.tmpdir.
1554 const char* os::get_temp_directory() { return "/tmp"; }
1555
1556 static bool file_exists(const char* filename) {
1557 struct stat statbuf;
1558 if (filename == NULL || strlen(filename) == 0) {
1559 return false;
1560 }
1561 return os::stat(filename, &statbuf) == 0;
1562 }
1563
1564 bool os::dll_build_name(char* buffer, size_t buflen,
1565 const char* pname, const char* fname) {
1566 bool retval = false;
1567 // Copied from libhpi
1568 const size_t pnamelen = pname ? strlen(pname) : 0;
1569
1570 // Return error on buffer overflow.
1571 if (pnamelen + strlen(fname) + 10 > (size_t) buflen) {
1572 return retval;
1573 }
1574
1575 if (pnamelen == 0) {
1576 snprintf(buffer, buflen, "lib%s.so", fname);
1577 retval = true;
1578 } else if (strchr(pname, *os::path_separator()) != NULL) {
1579 int n;
1580 char** pelements = split_path(pname, &n);
1581 if (pelements == NULL) {
1582 return false;
1583 }
1584 for (int i = 0 ; i < n ; i++) {
1585 // Really shouldn't be NULL, but check can't hurt
1586 if (pelements[i] == NULL || strlen(pelements[i]) == 0) {
1587 continue; // skip the empty path values
1588 }
1589 snprintf(buffer, buflen, "%s/lib%s.so", pelements[i], fname);
1590 if (file_exists(buffer)) {
1591 retval = true;
1592 break;
1593 }
1594 }
1595 // release the storage
1596 for (int i = 0 ; i < n ; i++) {
1597 if (pelements[i] != NULL) {
1598 FREE_C_HEAP_ARRAY(char, pelements[i], mtInternal);
1599 }
1600 }
1601 if (pelements != NULL) {
1602 FREE_C_HEAP_ARRAY(char*, pelements, mtInternal);
1603 }
1604 } else {
1605 snprintf(buffer, buflen, "%s/lib%s.so", pname, fname);
1606 retval = true;
1607 }
1608 return retval;
1609 }
1610
1611 // check if addr is inside libjvm.so
1612 bool os::address_is_in_vm(address addr) {
1613 static address libjvm_base_addr;
1614 Dl_info dlinfo;
1615
1616 if (libjvm_base_addr == NULL) {
1617 if (dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo) != 0) {
1618 libjvm_base_addr = (address)dlinfo.dli_fbase;
1619 }
1620 assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm");
1621 }
1622
1623 if (dladdr((void *)addr, &dlinfo) != 0) {
1624 if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true;
1625 }
1626
1627 return false;
1628 }
1629
1630 bool os::dll_address_to_function_name(address addr, char *buf,
1631 int buflen, int *offset) {
1632 // buf is not optional, but offset is optional
1633 assert(buf != NULL, "sanity check");
1634
1635 Dl_info dlinfo;
1636
1637 if (dladdr((void*)addr, &dlinfo) != 0) {
1638 // see if we have a matching symbol
1639 if (dlinfo.dli_saddr != NULL && dlinfo.dli_sname != NULL) {
1640 if (!Decoder::demangle(dlinfo.dli_sname, buf, buflen)) {
1641 jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname);
1642 }
1643 if (offset != NULL) *offset = addr - (address)dlinfo.dli_saddr;
1644 return true;
1645 }
1646 // no matching symbol so try for just file info
1647 if (dlinfo.dli_fname != NULL && dlinfo.dli_fbase != NULL) {
1648 if (Decoder::decode((address)(addr - (address)dlinfo.dli_fbase),
1649 buf, buflen, offset, dlinfo.dli_fname)) {
1650 return true;
1651 }
1652 }
1653 }
1654
1655 buf[0] = '\0';
1656 if (offset != NULL) *offset = -1;
1657 return false;
1658 }
1659
1660 struct _address_to_library_name {
1661 address addr; // input : memory address
1662 size_t buflen; // size of fname
1663 char* fname; // output: library name
1664 address base; // library base addr
1665 };
1666
1667 static int address_to_library_name_callback(struct dl_phdr_info *info,
1668 size_t size, void *data) {
1669 int i;
1670 bool found = false;
1671 address libbase = NULL;
1672 struct _address_to_library_name * d = (struct _address_to_library_name *)data;
1673
1674 // iterate through all loadable segments
1675 for (i = 0; i < info->dlpi_phnum; i++) {
1676 address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr);
1677 if (info->dlpi_phdr[i].p_type == PT_LOAD) {
1678 // base address of a library is the lowest address of its loaded
1679 // segments.
1680 if (libbase == NULL || libbase > segbase) {
1681 libbase = segbase;
1682 }
1683 // see if 'addr' is within current segment
1684 if (segbase <= d->addr &&
1685 d->addr < segbase + info->dlpi_phdr[i].p_memsz) {
1686 found = true;
1687 }
1688 }
1689 }
1690
1691 // dlpi_name is NULL or empty if the ELF file is executable, return 0
1692 // so dll_address_to_library_name() can fall through to use dladdr() which
1693 // can figure out executable name from argv[0].
1694 if (found && info->dlpi_name && info->dlpi_name[0]) {
1695 d->base = libbase;
1696 if (d->fname) {
1697 jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name);
1698 }
1699 return 1;
1700 }
1701 return 0;
1702 }
1703
1704 bool os::dll_address_to_library_name(address addr, char* buf,
1705 int buflen, int* offset) {
1706 // buf is not optional, but offset is optional
1707 assert(buf != NULL, "sanity check");
1708
1709 Dl_info dlinfo;
1710 struct _address_to_library_name data;
1711
1712 // There is a bug in old glibc dladdr() implementation that it could resolve
1713 // to wrong library name if the .so file has a base address != NULL. Here
1714 // we iterate through the program headers of all loaded libraries to find
1715 // out which library 'addr' really belongs to. This workaround can be
1716 // removed once the minimum requirement for glibc is moved to 2.3.x.
1717 data.addr = addr;
1718 data.fname = buf;
1719 data.buflen = buflen;
1720 data.base = NULL;
1721 int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data);
1722
1723 if (rslt) {
1724 // buf already contains library name
1725 if (offset) *offset = addr - data.base;
1726 return true;
1727 }
1728 if (dladdr((void*)addr, &dlinfo) != 0) {
1729 if (dlinfo.dli_fname != NULL) {
1730 jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname);
1731 }
1732 if (dlinfo.dli_fbase != NULL && offset != NULL) {
1733 *offset = addr - (address)dlinfo.dli_fbase;
1734 }
1735 return true;
1736 }
1737
1738 buf[0] = '\0';
1739 if (offset) *offset = -1;
1740 return false;
1741 }
1742
1743 // Loads .dll/.so and
1744 // in case of error it checks if .dll/.so was built for the
1745 // same architecture as Hotspot is running on
1746
1747
1748 // Remember the stack's state. The Linux dynamic linker will change
1749 // the stack to 'executable' at most once, so we must safepoint only once.
1750 bool os::Linux::_stack_is_executable = false;
1751
1752 // VM operation that loads a library. This is necessary if stack protection
1753 // of the Java stacks can be lost during loading the library. If we
1754 // do not stop the Java threads, they can stack overflow before the stacks
1755 // are protected again.
1756 class VM_LinuxDllLoad: public VM_Operation {
1757 private:
1758 const char *_filename;
1759 char *_ebuf;
1760 int _ebuflen;
1761 void *_lib;
1762 public:
1763 VM_LinuxDllLoad(const char *fn, char *ebuf, int ebuflen) :
1764 _filename(fn), _ebuf(ebuf), _ebuflen(ebuflen), _lib(NULL) {}
1765 VMOp_Type type() const { return VMOp_LinuxDllLoad; }
1766 void doit() {
1767 _lib = os::Linux::dll_load_in_vmthread(_filename, _ebuf, _ebuflen);
1768 os::Linux::_stack_is_executable = true;
1769 }
1770 void* loaded_library() { return _lib; }
1771 };
1772
1773 void * os::dll_load(const char *filename, char *ebuf, int ebuflen)
1774 {
1775 void * result = NULL;
1776 bool load_attempted = false;
1777
1778 // Check whether the library to load might change execution rights
1779 // of the stack. If they are changed, the protection of the stack
1780 // guard pages will be lost. We need a safepoint to fix this.
1781 //
1782 // See Linux man page execstack(8) for more info.
1783 if (os::uses_stack_guard_pages() && !os::Linux::_stack_is_executable) {
1784 ElfFile ef(filename);
1785 if (!ef.specifies_noexecstack()) {
1786 if (!is_init_completed()) {
1787 os::Linux::_stack_is_executable = true;
1788 // This is OK - No Java threads have been created yet, and hence no
1789 // stack guard pages to fix.
1790 //
1791 // This should happen only when you are building JDK7 using a very
1792 // old version of JDK6 (e.g., with JPRT) and running test_gamma.
1793 //
1794 // Dynamic loader will make all stacks executable after
1795 // this function returns, and will not do that again.
1796 assert(Threads::first() == NULL, "no Java threads should exist yet.");
1797 } else {
1798 warning("You have loaded library %s which might have disabled stack guard. "
1799 "The VM will try to fix the stack guard now.\n"
1800 "It's highly recommended that you fix the library with "
1801 "'execstack -c <libfile>', or link it with '-z noexecstack'.",
1802 filename);
1803
1804 assert(Thread::current()->is_Java_thread(), "must be Java thread");
1805 JavaThread *jt = JavaThread::current();
1806 if (jt->thread_state() != _thread_in_native) {
1807 // This happens when a compiler thread tries to load a hsdis-<arch>.so file
1808 // that requires ExecStack. Cannot enter safe point. Let's give up.
1809 warning("Unable to fix stack guard. Giving up.");
1810 } else {
1811 if (!LoadExecStackDllInVMThread) {
1812 // This is for the case where the DLL has an static
1813 // constructor function that executes JNI code. We cannot
1814 // load such DLLs in the VMThread.
1815 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen);
1816 }
1817
1818 ThreadInVMfromNative tiv(jt);
1819 debug_only(VMNativeEntryWrapper vew;)
1820
1821 VM_LinuxDllLoad op(filename, ebuf, ebuflen);
1822 VMThread::execute(&op);
1823 if (LoadExecStackDllInVMThread) {
1824 result = op.loaded_library();
1825 }
1826 load_attempted = true;
1827 }
1828 }
1829 }
1830 }
1831
1832 if (!load_attempted) {
1833 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen);
1834 }
1835
1836 if (result != NULL) {
1837 // Successful loading
1838 return result;
1839 }
1840
1841 Elf32_Ehdr elf_head;
1842 int diag_msg_max_length=ebuflen-strlen(ebuf);
1843 char* diag_msg_buf=ebuf+strlen(ebuf);
1844
1845 if (diag_msg_max_length==0) {
1846 // No more space in ebuf for additional diagnostics message
1847 return NULL;
1848 }
1849
1850
1851 int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK);
1852
1853 if (file_descriptor < 0) {
1854 // Can't open library, report dlerror() message
1855 return NULL;
1856 }
1857
1858 bool failed_to_read_elf_head=
1859 (sizeof(elf_head)!=
1860 (::read(file_descriptor, &elf_head,sizeof(elf_head)))) ;
1861
1862 ::close(file_descriptor);
1863 if (failed_to_read_elf_head) {
1864 // file i/o error - report dlerror() msg
1865 return NULL;
1866 }
1867
1868 typedef struct {
1869 Elf32_Half code; // Actual value as defined in elf.h
1870 Elf32_Half compat_class; // Compatibility of archs at VM's sense
1871 char elf_class; // 32 or 64 bit
1872 char endianess; // MSB or LSB
1873 char* name; // String representation
1874 } arch_t;
1875
1876 #ifndef EM_486
1877 #define EM_486 6 /* Intel 80486 */
1878 #endif
1879
1880 static const arch_t arch_array[]={
1881 {EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
1882 {EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
1883 {EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"},
1884 {EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"},
1885 {EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
1886 {EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
1887 {EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"},
1888 {EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"},
1889 #if defined(VM_LITTLE_ENDIAN)
1890 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2LSB, (char*)"Power PC 64"},
1891 #else
1892 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"},
1893 #endif
1894 {EM_ARM, EM_ARM, ELFCLASS32, ELFDATA2LSB, (char*)"ARM"},
1895 {EM_S390, EM_S390, ELFCLASSNONE, ELFDATA2MSB, (char*)"IBM System/390"},
1896 {EM_ALPHA, EM_ALPHA, ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"},
1897 {EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"},
1898 {EM_MIPS, EM_MIPS, ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"},
1899 {EM_PARISC, EM_PARISC, ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"},
1900 {EM_68K, EM_68K, ELFCLASS32, ELFDATA2MSB, (char*)"M68k"}
1901 };
1902
1903 #if (defined IA32)
1904 static Elf32_Half running_arch_code=EM_386;
1905 #elif (defined AMD64)
1906 static Elf32_Half running_arch_code=EM_X86_64;
1907 #elif (defined IA64)
1908 static Elf32_Half running_arch_code=EM_IA_64;
1909 #elif (defined __sparc) && (defined _LP64)
1910 static Elf32_Half running_arch_code=EM_SPARCV9;
1911 #elif (defined __sparc) && (!defined _LP64)
1912 static Elf32_Half running_arch_code=EM_SPARC;
1913 #elif (defined __powerpc64__)
1914 static Elf32_Half running_arch_code=EM_PPC64;
1915 #elif (defined __powerpc__)
1916 static Elf32_Half running_arch_code=EM_PPC;
1917 #elif (defined ARM)
1918 static Elf32_Half running_arch_code=EM_ARM;
1919 #elif (defined S390)
1920 static Elf32_Half running_arch_code=EM_S390;
1921 #elif (defined ALPHA)
1922 static Elf32_Half running_arch_code=EM_ALPHA;
1923 #elif (defined MIPSEL)
1924 static Elf32_Half running_arch_code=EM_MIPS_RS3_LE;
1925 #elif (defined PARISC)
1926 static Elf32_Half running_arch_code=EM_PARISC;
1927 #elif (defined MIPS)
1928 static Elf32_Half running_arch_code=EM_MIPS;
1929 #elif (defined M68K)
1930 static Elf32_Half running_arch_code=EM_68K;
1931 #else
1932 #error Method os::dll_load requires that one of following is defined:\
1933 IA32, AMD64, IA64, __sparc, __powerpc__, ARM, S390, ALPHA, MIPS, MIPSEL, PARISC, M68K
1934 #endif
1935
1936 // Identify compatability class for VM's architecture and library's architecture
1937 // Obtain string descriptions for architectures
1938
1939 arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL};
1940 int running_arch_index=-1;
1941
1942 for (unsigned int i=0 ; i < ARRAY_SIZE(arch_array) ; i++ ) {
1943 if (running_arch_code == arch_array[i].code) {
1944 running_arch_index = i;
1945 }
1946 if (lib_arch.code == arch_array[i].code) {
1947 lib_arch.compat_class = arch_array[i].compat_class;
1948 lib_arch.name = arch_array[i].name;
1949 }
1950 }
1951
1952 assert(running_arch_index != -1,
1953 "Didn't find running architecture code (running_arch_code) in arch_array");
1954 if (running_arch_index == -1) {
1955 // Even though running architecture detection failed
1956 // we may still continue with reporting dlerror() message
1957 return NULL;
1958 }
1959
1960 if (lib_arch.endianess != arch_array[running_arch_index].endianess) {
1961 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)");
1962 return NULL;
1963 }
1964
1965 #ifndef S390
1966 if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) {
1967 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)");
1968 return NULL;
1969 }
1970 #endif // !S390
1971
1972 if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) {
1973 if ( lib_arch.name!=NULL ) {
1974 ::snprintf(diag_msg_buf, diag_msg_max_length-1,
1975 " (Possible cause: can't load %s-bit .so on a %s-bit platform)",
1976 lib_arch.name, arch_array[running_arch_index].name);
1977 } else {
1978 ::snprintf(diag_msg_buf, diag_msg_max_length-1,
1979 " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)",
1980 lib_arch.code,
1981 arch_array[running_arch_index].name);
1982 }
1983 }
1984
1985 return NULL;
1986 }
1987
1988 void * os::Linux::dlopen_helper(const char *filename, char *ebuf, int ebuflen) {
1989 void * result = ::dlopen(filename, RTLD_LAZY);
1990 if (result == NULL) {
1991 ::strncpy(ebuf, ::dlerror(), ebuflen - 1);
1992 ebuf[ebuflen-1] = '\0';
1993 }
1994 return result;
1995 }
1996
1997 void * os::Linux::dll_load_in_vmthread(const char *filename, char *ebuf, int ebuflen) {
1998 void * result = NULL;
1999 if (LoadExecStackDllInVMThread) {
2000 result = dlopen_helper(filename, ebuf, ebuflen);
2001 }
2002
2003 // Since 7019808, libjvm.so is linked with -noexecstack. If the VM loads a
2004 // library that requires an executable stack, or which does not have this
2005 // stack attribute set, dlopen changes the stack attribute to executable. The
2006 // read protection of the guard pages gets lost.
2007 //
2008 // Need to check _stack_is_executable again as multiple VM_LinuxDllLoad
2009 // may have been queued at the same time.
2010
2011 if (!_stack_is_executable) {
2012 JavaThread *jt = Threads::first();
2013
2014 while (jt) {
2015 if (!jt->stack_guard_zone_unused() && // Stack not yet fully initialized
2016 jt->stack_yellow_zone_enabled()) { // No pending stack overflow exceptions
2017 if (!os::guard_memory((char *) jt->stack_red_zone_base() - jt->stack_red_zone_size(),
2018 jt->stack_yellow_zone_size() + jt->stack_red_zone_size())) {
2019 warning("Attempt to reguard stack yellow zone failed.");
2020 }
2021 }
2022 jt = jt->next();
2023 }
2024 }
2025
2026 return result;
2027 }
2028
2029 /*
2030 * glibc-2.0 libdl is not MT safe. If you are building with any glibc,
2031 * chances are you might want to run the generated bits against glibc-2.0
2032 * libdl.so, so always use locking for any version of glibc.
2033 */
2034 void* os::dll_lookup(void* handle, const char* name) {
2035 pthread_mutex_lock(&dl_mutex);
2036 void* res = dlsym(handle, name);
2037 pthread_mutex_unlock(&dl_mutex);
2038 return res;
2039 }
2040
2041 void* os::get_default_process_handle() {
2042 return (void*)::dlopen(NULL, RTLD_LAZY);
2043 }
2044
2045 static bool _print_ascii_file(const char* filename, outputStream* st) {
2046 int fd = ::open(filename, O_RDONLY);
2047 if (fd == -1) {
2048 return false;
2049 }
2050
2051 char buf[32];
2052 int bytes;
2053 while ((bytes = ::read(fd, buf, sizeof(buf))) > 0) {
2054 st->print_raw(buf, bytes);
2055 }
2056
2057 ::close(fd);
2058
2059 return true;
2060 }
2061
2062 void os::print_dll_info(outputStream *st) {
2063 st->print_cr("Dynamic libraries:");
2064
2065 char fname[32];
2066 pid_t pid = os::Linux::gettid();
2067
2068 jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid);
2069
2070 if (!_print_ascii_file(fname, st)) {
2071 st->print("Can not get library information for pid = %d\n", pid);
2072 }
2073 }
2074
2075 void os::print_os_info_brief(outputStream* st) {
2076 os::Linux::print_distro_info(st);
2077
2078 os::Posix::print_uname_info(st);
2079
2080 os::Linux::print_libversion_info(st);
2081
2082 }
2083
2084 void os::print_os_info(outputStream* st) {
2085 st->print("OS:");
2086
2087 os::Linux::print_distro_info(st);
2088
2089 os::Posix::print_uname_info(st);
2090
2091 // Print warning if unsafe chroot environment detected
2092 if (unsafe_chroot_detected) {
2093 st->print("WARNING!! ");
2094 st->print_cr("%s", unstable_chroot_error);
2095 }
2096
2097 os::Linux::print_libversion_info(st);
2098
2099 os::Posix::print_rlimit_info(st);
2100
2101 os::Posix::print_load_average(st);
2102
2103 os::Linux::print_full_memory_info(st);
2104 }
2105
2106 // Try to identify popular distros.
2107 // Most Linux distributions have a /etc/XXX-release file, which contains
2108 // the OS version string. Newer Linux distributions have a /etc/lsb-release
2109 // file that also contains the OS version string. Some have more than one
2110 // /etc/XXX-release file (e.g. Mandrake has both /etc/mandrake-release and
2111 // /etc/redhat-release.), so the order is important.
2112 // Any Linux that is based on Redhat (i.e. Oracle, Mandrake, Sun JDS...) have
2113 // their own specific XXX-release file as well as a redhat-release file.
2114 // Because of this the XXX-release file needs to be searched for before the
2115 // redhat-release file.
2116 // Since Red Hat has a lsb-release file that is not very descriptive the
2117 // search for redhat-release needs to be before lsb-release.
2118 // Since the lsb-release file is the new standard it needs to be searched
2119 // before the older style release files.
2120 // Searching system-release (Red Hat) and os-release (other Linuxes) are a
2121 // next to last resort. The os-release file is a new standard that contains
2122 // distribution information and the system-release file seems to be an old
2123 // standard that has been replaced by the lsb-release and os-release files.
2124 // Searching for the debian_version file is the last resort. It contains
2125 // an informative string like "6.0.6" or "wheezy/sid". Because of this
2126 // "Debian " is printed before the contents of the debian_version file.
2127 void os::Linux::print_distro_info(outputStream* st) {
2128 if (!_print_ascii_file("/etc/oracle-release", st) &&
2129 !_print_ascii_file("/etc/mandriva-release", st) &&
2130 !_print_ascii_file("/etc/mandrake-release", st) &&
2131 !_print_ascii_file("/etc/sun-release", st) &&
2132 !_print_ascii_file("/etc/redhat-release", st) &&
2133 !_print_ascii_file("/etc/lsb-release", st) &&
2134 !_print_ascii_file("/etc/SuSE-release", st) &&
2135 !_print_ascii_file("/etc/turbolinux-release", st) &&
2136 !_print_ascii_file("/etc/gentoo-release", st) &&
2137 !_print_ascii_file("/etc/ltib-release", st) &&
2138 !_print_ascii_file("/etc/angstrom-version", st) &&
2139 !_print_ascii_file("/etc/system-release", st) &&
2140 !_print_ascii_file("/etc/os-release", st)) {
2141
2142 if (file_exists("/etc/debian_version")) {
2143 st->print("Debian ");
2144 _print_ascii_file("/etc/debian_version", st);
2145 } else {
2146 st->print("Linux");
2147 }
2148 }
2149 st->cr();
2150 }
2151
2152 void os::Linux::print_libversion_info(outputStream* st) {
2153 // libc, pthread
2154 st->print("libc:");
2155 st->print("%s ", os::Linux::glibc_version());
2156 st->print("%s ", os::Linux::libpthread_version());
2157 if (os::Linux::is_LinuxThreads()) {
2158 st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed");
2159 }
2160 st->cr();
2161 }
2162
2163 void os::Linux::print_full_memory_info(outputStream* st) {
2164 st->print("\n/proc/meminfo:\n");
2165 _print_ascii_file("/proc/meminfo", st);
2166 st->cr();
2167 }
2168
2169 void os::print_memory_info(outputStream* st) {
2170
2171 st->print("Memory:");
2172 st->print(" %dk page", os::vm_page_size()>>10);
2173
2174 // values in struct sysinfo are "unsigned long"
2175 struct sysinfo si;
2176 sysinfo(&si);
2177
2178 st->print(", physical " UINT64_FORMAT "k",
2179 os::physical_memory() >> 10);
2180 st->print("(" UINT64_FORMAT "k free)",
2181 os::available_memory() >> 10);
2182 st->print(", swap " UINT64_FORMAT "k",
2183 ((jlong)si.totalswap * si.mem_unit) >> 10);
2184 st->print("(" UINT64_FORMAT "k free)",
2185 ((jlong)si.freeswap * si.mem_unit) >> 10);
2186 st->cr();
2187 }
2188
2189 void os::pd_print_cpu_info(outputStream* st) {
2190 st->print("\n/proc/cpuinfo:\n");
2191 if (!_print_ascii_file("/proc/cpuinfo", st)) {
2192 st->print(" <Not Available>");
2193 }
2194 st->cr();
2195 }
2196
2197 void os::print_siginfo(outputStream* st, void* siginfo) {
2198 const siginfo_t* si = (const siginfo_t*)siginfo;
2199
2200 os::Posix::print_siginfo_brief(st, si);
2201 #if INCLUDE_CDS
2202 if (si && (si->si_signo == SIGBUS || si->si_signo == SIGSEGV) &&
2203 UseSharedSpaces) {
2204 FileMapInfo* mapinfo = FileMapInfo::current_info();
2205 if (mapinfo->is_in_shared_space(si->si_addr)) {
2206 st->print("\n\nError accessing class data sharing archive." \
2207 " Mapped file inaccessible during execution, " \
2208 " possible disk/network problem.");
2209 }
2210 }
2211 #endif
2212 st->cr();
2213 }
2214
2215
2216 static void print_signal_handler(outputStream* st, int sig,
2217 char* buf, size_t buflen);
2218
2219 void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) {
2220 st->print_cr("Signal Handlers:");
2221 print_signal_handler(st, SIGSEGV, buf, buflen);
2222 print_signal_handler(st, SIGBUS , buf, buflen);
2223 print_signal_handler(st, SIGFPE , buf, buflen);
2224 print_signal_handler(st, SIGPIPE, buf, buflen);
2225 print_signal_handler(st, SIGXFSZ, buf, buflen);
2226 print_signal_handler(st, SIGILL , buf, buflen);
2227 print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen);
2228 print_signal_handler(st, SR_signum, buf, buflen);
2229 print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen);
2230 print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen);
2231 print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen);
2232 print_signal_handler(st, BREAK_SIGNAL, buf, buflen);
2233 #if defined(PPC64)
2234 print_signal_handler(st, SIGTRAP, buf, buflen);
2235 #endif
2236 }
2237
2238 static char saved_jvm_path[MAXPATHLEN] = {0};
2239
2240 // Find the full path to the current module, libjvm.so
2241 void os::jvm_path(char *buf, jint buflen) {
2242 // Error checking.
2243 if (buflen < MAXPATHLEN) {
2244 assert(false, "must use a large-enough buffer");
2245 buf[0] = '\0';
2246 return;
2247 }
2248 // Lazy resolve the path to current module.
2249 if (saved_jvm_path[0] != 0) {
2250 strcpy(buf, saved_jvm_path);
2251 return;
2252 }
2253
2254 char dli_fname[MAXPATHLEN];
2255 bool ret = dll_address_to_library_name(
2256 CAST_FROM_FN_PTR(address, os::jvm_path),
2257 dli_fname, sizeof(dli_fname), NULL);
2258 assert(ret, "cannot locate libjvm");
2259 char *rp = NULL;
2260 if (ret && dli_fname[0] != '\0') {
2261 rp = realpath(dli_fname, buf);
2262 }
2263 if (rp == NULL)
2264 return;
2265
2266 if (Arguments::created_by_gamma_launcher()) {
2267 // Support for the gamma launcher. Typical value for buf is
2268 // "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so". If "/jre/lib/" appears at
2269 // the right place in the string, then assume we are installed in a JDK and
2270 // we're done. Otherwise, check for a JAVA_HOME environment variable and fix
2271 // up the path so it looks like libjvm.so is installed there (append a
2272 // fake suffix hotspot/libjvm.so).
2273 const char *p = buf + strlen(buf) - 1;
2274 for (int count = 0; p > buf && count < 5; ++count) {
2275 for (--p; p > buf && *p != '/'; --p)
2276 /* empty */ ;
2277 }
2278
2279 if (strncmp(p, "/jre/lib/", 9) != 0) {
2280 // Look for JAVA_HOME in the environment.
2281 char* java_home_var = ::getenv("JAVA_HOME");
2282 if (java_home_var != NULL && java_home_var[0] != 0) {
2283 char* jrelib_p;
2284 int len;
2285
2286 // Check the current module name "libjvm.so".
2287 p = strrchr(buf, '/');
2288 assert(strstr(p, "/libjvm") == p, "invalid library name");
2289
2290 rp = realpath(java_home_var, buf);
2291 if (rp == NULL)
2292 return;
2293
2294 // determine if this is a legacy image or modules image
2295 // modules image doesn't have "jre" subdirectory
2296 len = strlen(buf);
2297 assert(len < buflen, "Ran out of buffer room");
2298 jrelib_p = buf + len;
2299 snprintf(jrelib_p, buflen-len, "/jre/lib/%s", cpu_arch);
2300 if (0 != access(buf, F_OK)) {
2301 snprintf(jrelib_p, buflen-len, "/lib/%s", cpu_arch);
2302 }
2303
2304 if (0 == access(buf, F_OK)) {
2305 // Use current module name "libjvm.so"
2306 len = strlen(buf);
2307 snprintf(buf + len, buflen-len, "/hotspot/libjvm.so");
2308 } else {
2309 // Go back to path of .so
2310 rp = realpath(dli_fname, buf);
2311 if (rp == NULL)
2312 return;
2313 }
2314 }
2315 }
2316 }
2317
2318 strncpy(saved_jvm_path, buf, MAXPATHLEN);
2319 }
2320
2321 void os::print_jni_name_prefix_on(outputStream* st, int args_size) {
2322 // no prefix required, not even "_"
2323 }
2324
2325 void os::print_jni_name_suffix_on(outputStream* st, int args_size) {
2326 // no suffix required
2327 }
2328
2329 ////////////////////////////////////////////////////////////////////////////////
2330 // sun.misc.Signal support
2331
2332 static volatile jint sigint_count = 0;
2333
2334 static void
2335 UserHandler(int sig, void *siginfo, void *context) {
2336 // 4511530 - sem_post is serialized and handled by the manager thread. When
2337 // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We
2338 // don't want to flood the manager thread with sem_post requests.
2339 if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1)
2340 return;
2341
2342 // Ctrl-C is pressed during error reporting, likely because the error
2343 // handler fails to abort. Let VM die immediately.
2344 if (sig == SIGINT && is_error_reported()) {
2345 os::die();
2346 }
2347
2348 os::signal_notify(sig);
2349 }
2350
2351 void* os::user_handler() {
2352 return CAST_FROM_FN_PTR(void*, UserHandler);
2353 }
2354
2355 class Semaphore : public StackObj {
2356 public:
2357 Semaphore();
2358 ~Semaphore();
2359 void signal();
2360 void wait();
2361 bool trywait();
2362 bool timedwait(unsigned int sec, int nsec);
2363 private:
2364 sem_t _semaphore;
2365 };
2366
2367 Semaphore::Semaphore() {
2368 sem_init(&_semaphore, 0, 0);
2369 }
2370
2371 Semaphore::~Semaphore() {
2372 sem_destroy(&_semaphore);
2373 }
2374
2375 void Semaphore::signal() {
2376 sem_post(&_semaphore);
2377 }
2378
2379 void Semaphore::wait() {
2380 sem_wait(&_semaphore);
2381 }
2382
2383 bool Semaphore::trywait() {
2384 return sem_trywait(&_semaphore) == 0;
2385 }
2386
2387 bool Semaphore::timedwait(unsigned int sec, int nsec) {
2388
2389 struct timespec ts;
2390 // Semaphore's are always associated with CLOCK_REALTIME
2391 os::Linux::clock_gettime(CLOCK_REALTIME, &ts);
2392 // see unpackTime for discussion on overflow checking
2393 if (sec >= MAX_SECS) {
2394 ts.tv_sec += MAX_SECS;
2395 ts.tv_nsec = 0;
2396 } else {
2397 ts.tv_sec += sec;
2398 ts.tv_nsec += nsec;
2399 if (ts.tv_nsec >= NANOSECS_PER_SEC) {
2400 ts.tv_nsec -= NANOSECS_PER_SEC;
2401 ++ts.tv_sec; // note: this must be <= max_secs
2402 }
2403 }
2404
2405 while (1) {
2406 int result = sem_timedwait(&_semaphore, &ts);
2407 if (result == 0) {
2408 return true;
2409 } else if (errno == EINTR) {
2410 continue;
2411 } else if (errno == ETIMEDOUT) {
2412 return false;
2413 } else {
2414 return false;
2415 }
2416 }
2417 }
2418
2419 extern "C" {
2420 typedef void (*sa_handler_t)(int);
2421 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *);
2422 }
2423
2424 void* os::signal(int signal_number, void* handler) {
2425 struct sigaction sigAct, oldSigAct;
2426
2427 sigfillset(&(sigAct.sa_mask));
2428 sigAct.sa_flags = SA_RESTART|SA_SIGINFO;
2429 sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler);
2430
2431 if (sigaction(signal_number, &sigAct, &oldSigAct)) {
2432 // -1 means registration failed
2433 return (void *)-1;
2434 }
2435
2436 return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler);
2437 }
2438
2439 void os::signal_raise(int signal_number) {
2440 ::raise(signal_number);
2441 }
2442
2443 /*
2444 * The following code is moved from os.cpp for making this
2445 * code platform specific, which it is by its very nature.
2446 */
2447
2448 // Will be modified when max signal is changed to be dynamic
2449 int os::sigexitnum_pd() {
2450 return NSIG;
2451 }
2452
2453 // a counter for each possible signal value
2454 static volatile jint pending_signals[NSIG+1] = { 0 };
2455
2456 // Linux(POSIX) specific hand shaking semaphore.
2457 static sem_t sig_sem;
2458 static Semaphore sr_semaphore;
2459
2460 void os::signal_init_pd() {
2461 // Initialize signal structures
2462 ::memset((void*)pending_signals, 0, sizeof(pending_signals));
2463
2464 // Initialize signal semaphore
2465 ::sem_init(&sig_sem, 0, 0);
2466 }
2467
2468 void os::signal_notify(int sig) {
2469 Atomic::inc(&pending_signals[sig]);
2470 ::sem_post(&sig_sem);
2471 }
2472
2473 static int check_pending_signals(bool wait) {
2474 Atomic::store(0, &sigint_count);
2475 for (;;) {
2476 for (int i = 0; i < NSIG + 1; i++) {
2477 jint n = pending_signals[i];
2478 if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) {
2479 return i;
2480 }
2481 }
2482 if (!wait) {
2483 return -1;
2484 }
2485 JavaThread *thread = JavaThread::current();
2486 ThreadBlockInVM tbivm(thread);
2487
2488 bool threadIsSuspended;
2489 do {
2490 thread->set_suspend_equivalent();
2491 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
2492 ::sem_wait(&sig_sem);
2493
2494 // were we externally suspended while we were waiting?
2495 threadIsSuspended = thread->handle_special_suspend_equivalent_condition();
2496 if (threadIsSuspended) {
2497 //
2498 // The semaphore has been incremented, but while we were waiting
2499 // another thread suspended us. We don't want to continue running
2500 // while suspended because that would surprise the thread that
2501 // suspended us.
2502 //
2503 ::sem_post(&sig_sem);
2504
2505 thread->java_suspend_self();
2506 }
2507 } while (threadIsSuspended);
2508 }
2509 }
2510
2511 int os::signal_lookup() {
2512 return check_pending_signals(false);
2513 }
2514
2515 int os::signal_wait() {
2516 return check_pending_signals(true);
2517 }
2518
2519 ////////////////////////////////////////////////////////////////////////////////
2520 // Virtual Memory
2521
2522 int os::vm_page_size() {
2523 // Seems redundant as all get out
2524 assert(os::Linux::page_size() != -1, "must call os::init");
2525 return os::Linux::page_size();
2526 }
2527
2528 // Solaris allocates memory by pages.
2529 int os::vm_allocation_granularity() {
2530 assert(os::Linux::page_size() != -1, "must call os::init");
2531 return os::Linux::page_size();
2532 }
2533
2534 // Rationale behind this function:
2535 // current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable
2536 // mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get
2537 // samples for JITted code. Here we create private executable mapping over the code cache
2538 // and then we can use standard (well, almost, as mapping can change) way to provide
2539 // info for the reporting script by storing timestamp and location of symbol
2540 void linux_wrap_code(char* base, size_t size) {
2541 static volatile jint cnt = 0;
2542
2543 if (!UseOprofile) {
2544 return;
2545 }
2546
2547 char buf[PATH_MAX+1];
2548 int num = Atomic::add(1, &cnt);
2549
2550 snprintf(buf, sizeof(buf), "%s/hs-vm-%d-%d",
2551 os::get_temp_directory(), os::current_process_id(), num);
2552 unlink(buf);
2553
2554 int fd = ::open(buf, O_CREAT | O_RDWR, S_IRWXU);
2555
2556 if (fd != -1) {
2557 off_t rv = ::lseek(fd, size-2, SEEK_SET);
2558 if (rv != (off_t)-1) {
2559 if (::write(fd, "", 1) == 1) {
2560 mmap(base, size,
2561 PROT_READ|PROT_WRITE|PROT_EXEC,
2562 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0);
2563 }
2564 }
2565 ::close(fd);
2566 unlink(buf);
2567 }
2568 }
2569
2570 static bool recoverable_mmap_error(int err) {
2571 // See if the error is one we can let the caller handle. This
2572 // list of errno values comes from JBS-6843484. I can't find a
2573 // Linux man page that documents this specific set of errno
2574 // values so while this list currently matches Solaris, it may
2575 // change as we gain experience with this failure mode.
2576 switch (err) {
2577 case EBADF:
2578 case EINVAL:
2579 case ENOTSUP:
2580 // let the caller deal with these errors
2581 return true;
2582
2583 default:
2584 // Any remaining errors on this OS can cause our reserved mapping
2585 // to be lost. That can cause confusion where different data
2586 // structures think they have the same memory mapped. The worst
2587 // scenario is if both the VM and a library think they have the
2588 // same memory mapped.
2589 return false;
2590 }
2591 }
2592
2593 static void warn_fail_commit_memory(char* addr, size_t size, bool exec,
2594 int err) {
2595 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT
2596 ", %d) failed; error='%s' (errno=%d)", addr, size, exec,
2597 strerror(err), err);
2598 }
2599
2600 static void warn_fail_commit_memory(char* addr, size_t size,
2601 size_t alignment_hint, bool exec,
2602 int err) {
2603 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT
2604 ", " SIZE_FORMAT ", %d) failed; error='%s' (errno=%d)", addr, size,
2605 alignment_hint, exec, strerror(err), err);
2606 }
2607
2608 // NOTE: Linux kernel does not really reserve the pages for us.
2609 // All it does is to check if there are enough free pages
2610 // left at the time of mmap(). This could be a potential
2611 // problem.
2612 int os::Linux::commit_memory_impl(char* addr, size_t size, bool exec) {
2613 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
2614 uintptr_t res = (uintptr_t) ::mmap(addr, size, prot,
2615 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0);
2616 if (res != (uintptr_t) MAP_FAILED) {
2617 if (UseNUMAInterleaving) {
2618 numa_make_global(addr, size);
2619 }
2620 return 0;
2621 }
2622
2623 int err = errno; // save errno from mmap() call above
2624
2625 if (!recoverable_mmap_error(err)) {
2626 warn_fail_commit_memory(addr, size, exec, err);
2627 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, "committing reserved memory.");
2628 }
2629
2630 return err;
2631 }
2632
2633 bool os::pd_commit_memory(char* addr, size_t size, bool exec) {
2634 return os::Linux::commit_memory_impl(addr, size, exec) == 0;
2635 }
2636
2637 void os::pd_commit_memory_or_exit(char* addr, size_t size, bool exec,
2638 const char* mesg) {
2639 assert(mesg != NULL, "mesg must be specified");
2640 int err = os::Linux::commit_memory_impl(addr, size, exec);
2641 if (err != 0) {
2642 // the caller wants all commit errors to exit with the specified mesg:
2643 warn_fail_commit_memory(addr, size, exec, err);
2644 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg);
2645 }
2646 }
2647
2648 // Define MAP_HUGETLB here so we can build HotSpot on old systems.
2649 #ifndef MAP_HUGETLB
2650 #define MAP_HUGETLB 0x40000
2651 #endif
2652
2653 // Define MADV_HUGEPAGE here so we can build HotSpot on old systems.
2654 #ifndef MADV_HUGEPAGE
2655 #define MADV_HUGEPAGE 14
2656 #endif
2657
2658 int os::Linux::commit_memory_impl(char* addr, size_t size,
2659 size_t alignment_hint, bool exec) {
2660 int err = os::Linux::commit_memory_impl(addr, size, exec);
2661 if (err == 0) {
2662 realign_memory(addr, size, alignment_hint);
2663 }
2664 return err;
2665 }
2666
2667 bool os::pd_commit_memory(char* addr, size_t size, size_t alignment_hint,
2668 bool exec) {
2669 return os::Linux::commit_memory_impl(addr, size, alignment_hint, exec) == 0;
2670 }
2671
2672 void os::pd_commit_memory_or_exit(char* addr, size_t size,
2673 size_t alignment_hint, bool exec,
2674 const char* mesg) {
2675 assert(mesg != NULL, "mesg must be specified");
2676 int err = os::Linux::commit_memory_impl(addr, size, alignment_hint, exec);
2677 if (err != 0) {
2678 // the caller wants all commit errors to exit with the specified mesg:
2679 warn_fail_commit_memory(addr, size, alignment_hint, exec, err);
2680 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg);
2681 }
2682 }
2683
2684 void os::pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint) {
2685 if (UseTransparentHugePages && alignment_hint > (size_t)vm_page_size()) {
2686 // We don't check the return value: madvise(MADV_HUGEPAGE) may not
2687 // be supported or the memory may already be backed by huge pages.
2688 ::madvise(addr, bytes, MADV_HUGEPAGE);
2689 }
2690 }
2691
2692 void os::pd_free_memory(char *addr, size_t bytes, size_t alignment_hint) {
2693 // This method works by doing an mmap over an existing mmaping and effectively discarding
2694 // the existing pages. However it won't work for SHM-based large pages that cannot be
2695 // uncommitted at all. We don't do anything in this case to avoid creating a segment with
2696 // small pages on top of the SHM segment. This method always works for small pages, so we
2697 // allow that in any case.
2698 if (alignment_hint <= (size_t)os::vm_page_size() || can_commit_large_page_memory()) {
2699 commit_memory(addr, bytes, alignment_hint, !ExecMem);
2700 }
2701 }
2702
2703 void os::numa_make_global(char *addr, size_t bytes) {
2704 Linux::numa_interleave_memory(addr, bytes);
2705 }
2706
2707 // Define for numa_set_bind_policy(int). Setting the argument to 0 will set the
2708 // bind policy to MPOL_PREFERRED for the current thread.
2709 #define USE_MPOL_PREFERRED 0
2710
2711 void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) {
2712 // To make NUMA and large pages more robust when both enabled, we need to ease
2713 // the requirements on where the memory should be allocated. MPOL_BIND is the
2714 // default policy and it will force memory to be allocated on the specified
2715 // node. Changing this to MPOL_PREFERRED will prefer to allocate the memory on
2716 // the specified node, but will not force it. Using this policy will prevent
2717 // getting SIGBUS when trying to allocate large pages on NUMA nodes with no
2718 // free large pages.
2719 Linux::numa_set_bind_policy(USE_MPOL_PREFERRED);
2720 Linux::numa_tonode_memory(addr, bytes, lgrp_hint);
2721 }
2722
2723 bool os::numa_topology_changed() { return false; }
2724
2725 size_t os::numa_get_groups_num() {
2726 int max_node = Linux::numa_max_node();
2727 return max_node > 0 ? max_node + 1 : 1;
2728 }
2729
2730 int os::numa_get_group_id() {
2731 int cpu_id = Linux::sched_getcpu();
2732 if (cpu_id != -1) {
2733 int lgrp_id = Linux::get_node_by_cpu(cpu_id);
2734 if (lgrp_id != -1) {
2735 return lgrp_id;
2736 }
2737 }
2738 return 0;
2739 }
2740
2741 size_t os::numa_get_leaf_groups(int *ids, size_t size) {
2742 for (size_t i = 0; i < size; i++) {
2743 ids[i] = i;
2744 }
2745 return size;
2746 }
2747
2748 bool os::get_page_info(char *start, page_info* info) {
2749 return false;
2750 }
2751
2752 char *os::scan_pages(char *start, char* end, page_info* page_expected, page_info* page_found) {
2753 return end;
2754 }
2755
2756
2757 int os::Linux::sched_getcpu_syscall(void) {
2758 unsigned int cpu;
2759 int retval = -1;
2760
2761 #if defined(IA32)
2762 # ifndef SYS_getcpu
2763 # define SYS_getcpu 318
2764 # endif
2765 retval = syscall(SYS_getcpu, &cpu, NULL, NULL);
2766 #elif defined(AMD64)
2767 // Unfortunately we have to bring all these macros here from vsyscall.h
2768 // to be able to compile on old linuxes.
2769 # define __NR_vgetcpu 2
2770 # define VSYSCALL_START (-10UL << 20)
2771 # define VSYSCALL_SIZE 1024
2772 # define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr))
2773 typedef long (*vgetcpu_t)(unsigned int *cpu, unsigned int *node, unsigned long *tcache);
2774 vgetcpu_t vgetcpu = (vgetcpu_t)VSYSCALL_ADDR(__NR_vgetcpu);
2775 retval = vgetcpu(&cpu, NULL, NULL);
2776 #endif
2777
2778 return (retval == -1) ? retval : cpu;
2779 }
2780
2781 // Something to do with the numa-aware allocator needs these symbols
2782 extern "C" JNIEXPORT void numa_warn(int number, char *where, ...) { }
2783 extern "C" JNIEXPORT void numa_error(char *where) { }
2784 extern "C" JNIEXPORT int fork1() { return fork(); }
2785
2786
2787 // If we are running with libnuma version > 2, then we should
2788 // be trying to use symbols with versions 1.1
2789 // If we are running with earlier version, which did not have symbol versions,
2790 // we should use the base version.
2791 void* os::Linux::libnuma_dlsym(void* handle, const char *name) {
2792 void *f = dlvsym(handle, name, "libnuma_1.1");
2793 if (f == NULL) {
2794 f = dlsym(handle, name);
2795 }
2796 return f;
2797 }
2798
2799 bool os::Linux::libnuma_init() {
2800 // sched_getcpu() should be in libc.
2801 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t,
2802 dlsym(RTLD_DEFAULT, "sched_getcpu")));
2803
2804 // If it's not, try a direct syscall.
2805 if (sched_getcpu() == -1)
2806 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, (void*)&sched_getcpu_syscall));
2807
2808 if (sched_getcpu() != -1) { // Does it work?
2809 void *handle = dlopen("libnuma.so.1", RTLD_LAZY);
2810 if (handle != NULL) {
2811 set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t,
2812 libnuma_dlsym(handle, "numa_node_to_cpus")));
2813 set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t,
2814 libnuma_dlsym(handle, "numa_max_node")));
2815 set_numa_available(CAST_TO_FN_PTR(numa_available_func_t,
2816 libnuma_dlsym(handle, "numa_available")));
2817 set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t,
2818 libnuma_dlsym(handle, "numa_tonode_memory")));
2819 set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t,
2820 libnuma_dlsym(handle, "numa_interleave_memory")));
2821 set_numa_set_bind_policy(CAST_TO_FN_PTR(numa_set_bind_policy_func_t,
2822 libnuma_dlsym(handle, "numa_set_bind_policy")));
2823
2824
2825 if (numa_available() != -1) {
2826 set_numa_all_nodes((unsigned long*)libnuma_dlsym(handle, "numa_all_nodes"));
2827 // Create a cpu -> node mapping
2828 _cpu_to_node = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<int>(0, true);
2829 rebuild_cpu_to_node_map();
2830 return true;
2831 }
2832 }
2833 }
2834 return false;
2835 }
2836
2837 // rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id.
2838 // The table is later used in get_node_by_cpu().
2839 void os::Linux::rebuild_cpu_to_node_map() {
2840 const size_t NCPUS = 32768; // Since the buffer size computation is very obscure
2841 // in libnuma (possible values are starting from 16,
2842 // and continuing up with every other power of 2, but less
2843 // than the maximum number of CPUs supported by kernel), and
2844 // is a subject to change (in libnuma version 2 the requirements
2845 // are more reasonable) we'll just hardcode the number they use
2846 // in the library.
2847 const size_t BitsPerCLong = sizeof(long) * CHAR_BIT;
2848
2849 size_t cpu_num = os::active_processor_count();
2850 size_t cpu_map_size = NCPUS / BitsPerCLong;
2851 size_t cpu_map_valid_size =
2852 MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size);
2853
2854 cpu_to_node()->clear();
2855 cpu_to_node()->at_grow(cpu_num - 1);
2856 size_t node_num = numa_get_groups_num();
2857
2858 unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size, mtInternal);
2859 for (size_t i = 0; i < node_num; i++) {
2860 if (numa_node_to_cpus(i, cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) {
2861 for (size_t j = 0; j < cpu_map_valid_size; j++) {
2862 if (cpu_map[j] != 0) {
2863 for (size_t k = 0; k < BitsPerCLong; k++) {
2864 if (cpu_map[j] & (1UL << k)) {
2865 cpu_to_node()->at_put(j * BitsPerCLong + k, i);
2866 }
2867 }
2868 }
2869 }
2870 }
2871 }
2872 FREE_C_HEAP_ARRAY(unsigned long, cpu_map, mtInternal);
2873 }
2874
2875 int os::Linux::get_node_by_cpu(int cpu_id) {
2876 if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) {
2877 return cpu_to_node()->at(cpu_id);
2878 }
2879 return -1;
2880 }
2881
2882 GrowableArray<int>* os::Linux::_cpu_to_node;
2883 os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu;
2884 os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus;
2885 os::Linux::numa_max_node_func_t os::Linux::_numa_max_node;
2886 os::Linux::numa_available_func_t os::Linux::_numa_available;
2887 os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory;
2888 os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory;
2889 os::Linux::numa_set_bind_policy_func_t os::Linux::_numa_set_bind_policy;
2890 unsigned long* os::Linux::_numa_all_nodes;
2891
2892 bool os::pd_uncommit_memory(char* addr, size_t size) {
2893 uintptr_t res = (uintptr_t) ::mmap(addr, size, PROT_NONE,
2894 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0);
2895 return res != (uintptr_t) MAP_FAILED;
2896 }
2897
2898 static
2899 address get_stack_commited_bottom(address bottom, size_t size) {
2900 address nbot = bottom;
2901 address ntop = bottom + size;
2902
2903 size_t page_sz = os::vm_page_size();
2904 unsigned pages = size / page_sz;
2905
2906 unsigned char vec[1];
2907 unsigned imin = 1, imax = pages + 1, imid;
2908 int mincore_return_value = 0;
2909
2910 assert(imin <= imax, "Unexpected page size");
2911
2912 while (imin < imax) {
2913 imid = (imax + imin) / 2;
2914 nbot = ntop - (imid * page_sz);
2915
2916 // Use a trick with mincore to check whether the page is mapped or not.
2917 // mincore sets vec to 1 if page resides in memory and to 0 if page
2918 // is swapped output but if page we are asking for is unmapped
2919 // it returns -1,ENOMEM
2920 mincore_return_value = mincore(nbot, page_sz, vec);
2921
2922 if (mincore_return_value == -1) {
2923 // Page is not mapped go up
2924 // to find first mapped page
2925 if (errno != EAGAIN) {
2926 assert(errno == ENOMEM, "Unexpected mincore errno");
2927 imax = imid;
2928 }
2929 } else {
2930 // Page is mapped go down
2931 // to find first not mapped page
2932 imin = imid + 1;
2933 }
2934 }
2935
2936 nbot = nbot + page_sz;
2937
2938 // Adjust stack bottom one page up if last checked page is not mapped
2939 if (mincore_return_value == -1) {
2940 nbot = nbot + page_sz;
2941 }
2942
2943 return nbot;
2944 }
2945
2946
2947 // Linux uses a growable mapping for the stack, and if the mapping for
2948 // the stack guard pages is not removed when we detach a thread the
2949 // stack cannot grow beyond the pages where the stack guard was
2950 // mapped. If at some point later in the process the stack expands to
2951 // that point, the Linux kernel cannot expand the stack any further
2952 // because the guard pages are in the way, and a segfault occurs.
2953 //
2954 // However, it's essential not to split the stack region by unmapping
2955 // a region (leaving a hole) that's already part of the stack mapping,
2956 // so if the stack mapping has already grown beyond the guard pages at
2957 // the time we create them, we have to truncate the stack mapping.
2958 // So, we need to know the extent of the stack mapping when
2959 // create_stack_guard_pages() is called.
2960
2961 // We only need this for stacks that are growable: at the time of
2962 // writing thread stacks don't use growable mappings (i.e. those
2963 // creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this
2964 // only applies to the main thread.
2965
2966 // If the (growable) stack mapping already extends beyond the point
2967 // where we're going to put our guard pages, truncate the mapping at
2968 // that point by munmap()ping it. This ensures that when we later
2969 // munmap() the guard pages we don't leave a hole in the stack
2970 // mapping. This only affects the main/initial thread
2971
2972 bool os::pd_create_stack_guard_pages(char* addr, size_t size) {
2973
2974 if (os::Linux::is_initial_thread()) {
2975 // As we manually grow stack up to bottom inside create_attached_thread(),
2976 // it's likely that os::Linux::initial_thread_stack_bottom is mapped and
2977 // we don't need to do anything special.
2978 // Check it first, before calling heavy function.
2979 uintptr_t stack_extent = (uintptr_t) os::Linux::initial_thread_stack_bottom();
2980 unsigned char vec[1];
2981
2982 if (mincore((address)stack_extent, os::vm_page_size(), vec) == -1) {
2983 // Fallback to slow path on all errors, including EAGAIN
2984 stack_extent = (uintptr_t) get_stack_commited_bottom(
2985 os::Linux::initial_thread_stack_bottom(),
2986 (size_t)addr - stack_extent);
2987 }
2988
2989 if (stack_extent < (uintptr_t)addr) {
2990 ::munmap((void*)stack_extent, (uintptr_t)(addr - stack_extent));
2991 }
2992 }
2993
2994 return os::commit_memory(addr, size, !ExecMem);
2995 }
2996
2997 // If this is a growable mapping, remove the guard pages entirely by
2998 // munmap()ping them. If not, just call uncommit_memory(). This only
2999 // affects the main/initial thread, but guard against future OS changes
3000 // It's safe to always unmap guard pages for initial thread because we
3001 // always place it right after end of the mapped region
3002
3003 bool os::remove_stack_guard_pages(char* addr, size_t size) {
3004 uintptr_t stack_extent, stack_base;
3005
3006 if (os::Linux::is_initial_thread()) {
3007 return ::munmap(addr, size) == 0;
3008 }
3009
3010 return os::uncommit_memory(addr, size);
3011 }
3012
3013 static address _highest_vm_reserved_address = NULL;
3014
3015 // If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory
3016 // at 'requested_addr'. If there are existing memory mappings at the same
3017 // location, however, they will be overwritten. If 'fixed' is false,
3018 // 'requested_addr' is only treated as a hint, the return value may or
3019 // may not start from the requested address. Unlike Linux mmap(), this
3020 // function returns NULL to indicate failure.
3021 static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) {
3022 char * addr;
3023 int flags;
3024
3025 flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS;
3026 if (fixed) {
3027 assert((uintptr_t)requested_addr % os::Linux::page_size() == 0, "unaligned address");
3028 flags |= MAP_FIXED;
3029 }
3030
3031 // Map reserved/uncommitted pages PROT_NONE so we fail early if we
3032 // touch an uncommitted page. Otherwise, the read/write might
3033 // succeed if we have enough swap space to back the physical page.
3034 addr = (char*)::mmap(requested_addr, bytes, PROT_NONE,
3035 flags, -1, 0);
3036
3037 if (addr != MAP_FAILED) {
3038 // anon_mmap() should only get called during VM initialization,
3039 // don't need lock (actually we can skip locking even it can be called
3040 // from multiple threads, because _highest_vm_reserved_address is just a
3041 // hint about the upper limit of non-stack memory regions.)
3042 if ((address)addr + bytes > _highest_vm_reserved_address) {
3043 _highest_vm_reserved_address = (address)addr + bytes;
3044 }
3045 }
3046
3047 return addr == MAP_FAILED ? NULL : addr;
3048 }
3049
3050 // Don't update _highest_vm_reserved_address, because there might be memory
3051 // regions above addr + size. If so, releasing a memory region only creates
3052 // a hole in the address space, it doesn't help prevent heap-stack collision.
3053 //
3054 static int anon_munmap(char * addr, size_t size) {
3055 return ::munmap(addr, size) == 0;
3056 }
3057
3058 char* os::pd_reserve_memory(size_t bytes, char* requested_addr,
3059 size_t alignment_hint) {
3060 return anon_mmap(requested_addr, bytes, (requested_addr != NULL));
3061 }
3062
3063 bool os::pd_release_memory(char* addr, size_t size) {
3064 return anon_munmap(addr, size);
3065 }
3066
3067 static address highest_vm_reserved_address() {
3068 return _highest_vm_reserved_address;
3069 }
3070
3071 static bool linux_mprotect(char* addr, size_t size, int prot) {
3072 // Linux wants the mprotect address argument to be page aligned.
3073 char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::page_size());
3074
3075 // According to SUSv3, mprotect() should only be used with mappings
3076 // established by mmap(), and mmap() always maps whole pages. Unaligned
3077 // 'addr' likely indicates problem in the VM (e.g. trying to change
3078 // protection of malloc'ed or statically allocated memory). Check the
3079 // caller if you hit this assert.
3080 assert(addr == bottom, "sanity check");
3081
3082 size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Linux::page_size());
3083 return ::mprotect(bottom, size, prot) == 0;
3084 }
3085
3086 // Set protections specified
3087 bool os::protect_memory(char* addr, size_t bytes, ProtType prot,
3088 bool is_committed) {
3089 unsigned int p = 0;
3090 switch (prot) {
3091 case MEM_PROT_NONE: p = PROT_NONE; break;
3092 case MEM_PROT_READ: p = PROT_READ; break;
3093 case MEM_PROT_RW: p = PROT_READ|PROT_WRITE; break;
3094 case MEM_PROT_RWX: p = PROT_READ|PROT_WRITE|PROT_EXEC; break;
3095 default:
3096 ShouldNotReachHere();
3097 }
3098 // is_committed is unused.
3099 return linux_mprotect(addr, bytes, p);
3100 }
3101
3102 bool os::guard_memory(char* addr, size_t size) {
3103 return linux_mprotect(addr, size, PROT_NONE);
3104 }
3105
3106 bool os::unguard_memory(char* addr, size_t size) {
3107 return linux_mprotect(addr, size, PROT_READ|PROT_WRITE);
3108 }
3109
3110 bool os::Linux::transparent_huge_pages_sanity_check(bool warn, size_t page_size) {
3111 bool result = false;
3112 void *p = mmap(NULL, page_size * 2, PROT_READ|PROT_WRITE,
3113 MAP_ANONYMOUS|MAP_PRIVATE,
3114 -1, 0);
3115 if (p != MAP_FAILED) {
3116 void *aligned_p = align_ptr_up(p, page_size);
3117
3118 result = madvise(aligned_p, page_size, MADV_HUGEPAGE) == 0;
3119
3120 munmap(p, page_size * 2);
3121 }
3122
3123 if (warn && !result) {
3124 warning("TransparentHugePages is not supported by the operating system.");
3125 }
3126
3127 return result;
3128 }
3129
3130 bool os::Linux::hugetlbfs_sanity_check(bool warn, size_t page_size) {
3131 bool result = false;
3132 void *p = mmap(NULL, page_size, PROT_READ|PROT_WRITE,
3133 MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB,
3134 -1, 0);
3135
3136 if (p != MAP_FAILED) {
3137 // We don't know if this really is a huge page or not.
3138 FILE *fp = fopen("/proc/self/maps", "r");
3139 if (fp) {
3140 while (!feof(fp)) {
3141 char chars[257];
3142 long x = 0;
3143 if (fgets(chars, sizeof(chars), fp)) {
3144 if (sscanf(chars, "%lx-%*x", &x) == 1
3145 && x == (long)p) {
3146 if (strstr (chars, "hugepage")) {
3147 result = true;
3148 break;
3149 }
3150 }
3151 }
3152 }
3153 fclose(fp);
3154 }
3155 munmap(p, page_size);
3156 }
3157
3158 if (warn && !result) {
3159 warning("HugeTLBFS is not supported by the operating system.");
3160 }
3161
3162 return result;
3163 }
3164
3165 /*
3166 * Set the coredump_filter bits to include largepages in core dump (bit 6)
3167 *
3168 * From the coredump_filter documentation:
3169 *
3170 * - (bit 0) anonymous private memory
3171 * - (bit 1) anonymous shared memory
3172 * - (bit 2) file-backed private memory
3173 * - (bit 3) file-backed shared memory
3174 * - (bit 4) ELF header pages in file-backed private memory areas (it is
3175 * effective only if the bit 2 is cleared)
3176 * - (bit 5) hugetlb private memory
3177 * - (bit 6) hugetlb shared memory
3178 */
3179 static void set_coredump_filter(void) {
3180 FILE *f;
3181 long cdm;
3182
3183 if ((f = fopen("/proc/self/coredump_filter", "r+")) == NULL) {
3184 return;
3185 }
3186
3187 if (fscanf(f, "%lx", &cdm) != 1) {
3188 fclose(f);
3189 return;
3190 }
3191
3192 rewind(f);
3193
3194 if ((cdm & LARGEPAGES_BIT) == 0) {
3195 cdm |= LARGEPAGES_BIT;
3196 fprintf(f, "%#lx", cdm);
3197 }
3198
3199 fclose(f);
3200 }
3201
3202 // Large page support
3203
3204 static size_t _large_page_size = 0;
3205
3206 size_t os::Linux::find_large_page_size() {
3207 size_t large_page_size = 0;
3208
3209 // large_page_size on Linux is used to round up heap size. x86 uses either
3210 // 2M or 4M page, depending on whether PAE (Physical Address Extensions)
3211 // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use
3212 // page as large as 256M.
3213 //
3214 // Here we try to figure out page size by parsing /proc/meminfo and looking
3215 // for a line with the following format:
3216 // Hugepagesize: 2048 kB
3217 //
3218 // If we can't determine the value (e.g. /proc is not mounted, or the text
3219 // format has been changed), we'll use the largest page size supported by
3220 // the processor.
3221
3222 #ifndef ZERO
3223 large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M)
3224 ARM_ONLY(2 * M) PPC_ONLY(4 * M);
3225 #endif // ZERO
3226
3227 FILE *fp = fopen("/proc/meminfo", "r");
3228 if (fp) {
3229 while (!feof(fp)) {
3230 int x = 0;
3231 char buf[16];
3232 if (fscanf(fp, "Hugepagesize: %d", &x) == 1) {
3233 if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) {
3234 large_page_size = x * K;
3235 break;
3236 }
3237 } else {
3238 // skip to next line
3239 for (;;) {
3240 int ch = fgetc(fp);
3241 if (ch == EOF || ch == (int)'\n') break;
3242 }
3243 }
3244 }
3245 fclose(fp);
3246 }
3247
3248 if (!FLAG_IS_DEFAULT(LargePageSizeInBytes) && LargePageSizeInBytes != large_page_size) {
3249 warning("Setting LargePageSizeInBytes has no effect on this OS. Large page size is "
3250 SIZE_FORMAT "%s.", byte_size_in_proper_unit(large_page_size),
3251 proper_unit_for_byte_size(large_page_size));
3252 }
3253
3254 return large_page_size;
3255 }
3256
3257 size_t os::Linux::setup_large_page_size() {
3258 _large_page_size = Linux::find_large_page_size();
3259 const size_t default_page_size = (size_t)Linux::page_size();
3260 if (_large_page_size > default_page_size) {
3261 _page_sizes[0] = _large_page_size;
3262 _page_sizes[1] = default_page_size;
3263 _page_sizes[2] = 0;
3264 }
3265
3266 return _large_page_size;
3267 }
3268
3269 bool os::Linux::setup_large_page_type(size_t page_size) {
3270 if (FLAG_IS_DEFAULT(UseHugeTLBFS) &&
3271 FLAG_IS_DEFAULT(UseSHM) &&
3272 FLAG_IS_DEFAULT(UseTransparentHugePages)) {
3273
3274 // The type of large pages has not been specified by the user.
3275
3276 // Try UseHugeTLBFS and then UseSHM.
3277 UseHugeTLBFS = UseSHM = true;
3278
3279 // Don't try UseTransparentHugePages since there are known
3280 // performance issues with it turned on. This might change in the future.
3281 UseTransparentHugePages = false;
3282 }
3283
3284 if (UseTransparentHugePages) {
3285 bool warn_on_failure = !FLAG_IS_DEFAULT(UseTransparentHugePages);
3286 if (transparent_huge_pages_sanity_check(warn_on_failure, page_size)) {
3287 UseHugeTLBFS = false;
3288 UseSHM = false;
3289 return true;
3290 }
3291 UseTransparentHugePages = false;
3292 }
3293
3294 if (UseHugeTLBFS) {
3295 bool warn_on_failure = !FLAG_IS_DEFAULT(UseHugeTLBFS);
3296 if (hugetlbfs_sanity_check(warn_on_failure, page_size)) {
3297 UseSHM = false;
3298 return true;
3299 }
3300 UseHugeTLBFS = false;
3301 }
3302
3303 return UseSHM;
3304 }
3305
3306 void os::large_page_init() {
3307 if (!UseLargePages &&
3308 !UseTransparentHugePages &&
3309 !UseHugeTLBFS &&
3310 !UseSHM) {
3311 // Not using large pages.
3312 return;
3313 }
3314
3315 if (!FLAG_IS_DEFAULT(UseLargePages) && !UseLargePages) {
3316 // The user explicitly turned off large pages.
3317 // Ignore the rest of the large pages flags.
3318 UseTransparentHugePages = false;
3319 UseHugeTLBFS = false;
3320 UseSHM = false;
3321 return;
3322 }
3323
3324 size_t large_page_size = Linux::setup_large_page_size();
3325 UseLargePages = Linux::setup_large_page_type(large_page_size);
3326
3327 set_coredump_filter();
3328 }
3329
3330 #ifndef SHM_HUGETLB
3331 #define SHM_HUGETLB 04000
3332 #endif
3333
3334 char* os::Linux::reserve_memory_special_shm(size_t bytes, size_t alignment, char* req_addr, bool exec) {
3335 // "exec" is passed in but not used. Creating the shared image for
3336 // the code cache doesn't have an SHM_X executable permission to check.
3337 assert(UseLargePages && UseSHM, "only for SHM large pages");
3338 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address");
3339
3340 if (!is_size_aligned(bytes, os::large_page_size()) || alignment > os::large_page_size()) {
3341 return NULL; // Fallback to small pages.
3342 }
3343
3344 key_t key = IPC_PRIVATE;
3345 char *addr;
3346
3347 bool warn_on_failure = UseLargePages &&
3348 (!FLAG_IS_DEFAULT(UseLargePages) ||
3349 !FLAG_IS_DEFAULT(UseSHM) ||
3350 !FLAG_IS_DEFAULT(LargePageSizeInBytes)
3351 );
3352 char msg[128];
3353
3354 // Create a large shared memory region to attach to based on size.
3355 // Currently, size is the total size of the heap
3356 int shmid = shmget(key, bytes, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W);
3357 if (shmid == -1) {
3358 // Possible reasons for shmget failure:
3359 // 1. shmmax is too small for Java heap.
3360 // > check shmmax value: cat /proc/sys/kernel/shmmax
3361 // > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax
3362 // 2. not enough large page memory.
3363 // > check available large pages: cat /proc/meminfo
3364 // > increase amount of large pages:
3365 // echo new_value > /proc/sys/vm/nr_hugepages
3366 // Note 1: different Linux may use different name for this property,
3367 // e.g. on Redhat AS-3 it is "hugetlb_pool".
3368 // Note 2: it's possible there's enough physical memory available but
3369 // they are so fragmented after a long run that they can't
3370 // coalesce into large pages. Try to reserve large pages when
3371 // the system is still "fresh".
3372 if (warn_on_failure) {
3373 jio_snprintf(msg, sizeof(msg), "Failed to reserve shared memory (errno = %d).", errno);
3374 warning("%s", msg);
3375 }
3376 return NULL;
3377 }
3378
3379 // attach to the region
3380 addr = (char*)shmat(shmid, req_addr, 0);
3381 int err = errno;
3382
3383 // Remove shmid. If shmat() is successful, the actual shared memory segment
3384 // will be deleted when it's detached by shmdt() or when the process
3385 // terminates. If shmat() is not successful this will remove the shared
3386 // segment immediately.
3387 shmctl(shmid, IPC_RMID, NULL);
3388
3389 if ((intptr_t)addr == -1) {
3390 if (warn_on_failure) {
3391 jio_snprintf(msg, sizeof(msg), "Failed to attach shared memory (errno = %d).", err);
3392 warning("%s", msg);
3393 }
3394 return NULL;
3395 }
3396
3397 return addr;
3398 }
3399
3400 static void warn_on_large_pages_failure(char* req_addr, size_t bytes, int error) {
3401 assert(error == ENOMEM, "Only expect to fail if no memory is available");
3402
3403 bool warn_on_failure = UseLargePages &&
3404 (!FLAG_IS_DEFAULT(UseLargePages) ||
3405 !FLAG_IS_DEFAULT(UseHugeTLBFS) ||
3406 !FLAG_IS_DEFAULT(LargePageSizeInBytes));
3407
3408 if (warn_on_failure) {
3409 char msg[128];
3410 jio_snprintf(msg, sizeof(msg), "Failed to reserve large pages memory req_addr: "
3411 PTR_FORMAT " bytes: " SIZE_FORMAT " (errno = %d).", req_addr, bytes, error);
3412 warning("%s", msg);
3413 }
3414 }
3415
3416 char* os::Linux::reserve_memory_special_huge_tlbfs_only(size_t bytes, char* req_addr, bool exec) {
3417 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages");
3418 assert(is_size_aligned(bytes, os::large_page_size()), "Unaligned size");
3419 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address");
3420
3421 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
3422 char* addr = (char*)::mmap(req_addr, bytes, prot,
3423 MAP_PRIVATE|MAP_ANONYMOUS|MAP_HUGETLB,
3424 -1, 0);
3425
3426 if (addr == MAP_FAILED) {
3427 warn_on_large_pages_failure(req_addr, bytes, errno);
3428 return NULL;
3429 }
3430
3431 assert(is_ptr_aligned(addr, os::large_page_size()), "Must be");
3432
3433 return addr;
3434 }
3435
3436 char* os::Linux::reserve_memory_special_huge_tlbfs_mixed(size_t bytes, size_t alignment, char* req_addr, bool exec) {
3437 size_t large_page_size = os::large_page_size();
3438
3439 assert(bytes >= large_page_size, "Shouldn't allocate large pages for small sizes");
3440
3441 // Allocate small pages.
3442
3443 char* start;
3444 if (req_addr != NULL) {
3445 assert(is_ptr_aligned(req_addr, alignment), "Must be");
3446 assert(is_size_aligned(bytes, alignment), "Must be");
3447 start = os::reserve_memory(bytes, req_addr);
3448 assert(start == NULL || start == req_addr, "Must be");
3449 } else {
3450 start = os::reserve_memory_aligned(bytes, alignment);
3451 }
3452
3453 if (start == NULL) {
3454 return NULL;
3455 }
3456
3457 assert(is_ptr_aligned(start, alignment), "Must be");
3458
3459 if (MemTracker::tracking_level() > NMT_minimal) {
3460 // os::reserve_memory_special will record this memory area.
3461 // Need to release it here to prevent overlapping reservations.
3462 Tracker tkr = MemTracker::get_virtual_memory_release_tracker();
3463 tkr.record((address)start, bytes);
3464 }
3465
3466 char* end = start + bytes;
3467
3468 // Find the regions of the allocated chunk that can be promoted to large pages.
3469 char* lp_start = (char*)align_ptr_up(start, large_page_size);
3470 char* lp_end = (char*)align_ptr_down(end, large_page_size);
3471
3472 size_t lp_bytes = lp_end - lp_start;
3473
3474 assert(is_size_aligned(lp_bytes, large_page_size), "Must be");
3475
3476 if (lp_bytes == 0) {
3477 // The mapped region doesn't even span the start and the end of a large page.
3478 // Fall back to allocate a non-special area.
3479 ::munmap(start, end - start);
3480 return NULL;
3481 }
3482
3483 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
3484
3485
3486 void* result;
3487
3488 if (start != lp_start) {
3489 result = ::mmap(start, lp_start - start, prot,
3490 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED,
3491 -1, 0);
3492 if (result == MAP_FAILED) {
3493 ::munmap(lp_start, end - lp_start);
3494 return NULL;
3495 }
3496 }
3497
3498 result = ::mmap(lp_start, lp_bytes, prot,
3499 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED|MAP_HUGETLB,
3500 -1, 0);
3501 if (result == MAP_FAILED) {
3502 warn_on_large_pages_failure(req_addr, bytes, errno);
3503 // If the mmap above fails, the large pages region will be unmapped and we
3504 // have regions before and after with small pages. Release these regions.
3505 //
3506 // | mapped | unmapped | mapped |
3507 // ^ ^ ^ ^
3508 // start lp_start lp_end end
3509 //
3510 ::munmap(start, lp_start - start);
3511 ::munmap(lp_end, end - lp_end);
3512 return NULL;
3513 }
3514
3515 if (lp_end != end) {
3516 result = ::mmap(lp_end, end - lp_end, prot,
3517 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED,
3518 -1, 0);
3519 if (result == MAP_FAILED) {
3520 ::munmap(start, lp_end - start);
3521 return NULL;
3522 }
3523 }
3524
3525 return start;
3526 }
3527
3528 char* os::Linux::reserve_memory_special_huge_tlbfs(size_t bytes, size_t alignment, char* req_addr, bool exec) {
3529 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages");
3530 assert(is_ptr_aligned(req_addr, alignment), "Must be");
3531 assert(is_power_of_2(alignment), "Must be");
3532 assert(is_power_of_2(os::large_page_size()), "Must be");
3533 assert(bytes >= os::large_page_size(), "Shouldn't allocate large pages for small sizes");
3534
3535 if (is_size_aligned(bytes, os::large_page_size()) && alignment <= os::large_page_size()) {
3536 return reserve_memory_special_huge_tlbfs_only(bytes, req_addr, exec);
3537 } else {
3538 return reserve_memory_special_huge_tlbfs_mixed(bytes, alignment, req_addr, exec);
3539 }
3540 }
3541
3542 char* os::reserve_memory_special(size_t bytes, size_t alignment, char* req_addr, bool exec) {
3543 assert(UseLargePages, "only for large pages");
3544
3545 char* addr;
3546 if (UseSHM) {
3547 addr = os::Linux::reserve_memory_special_shm(bytes, alignment, req_addr, exec);
3548 } else {
3549 assert(UseHugeTLBFS, "must be");
3550 addr = os::Linux::reserve_memory_special_huge_tlbfs(bytes, alignment, req_addr, exec);
3551 }
3552
3553 if (addr != NULL) {
3554 if (UseNUMAInterleaving) {
3555 numa_make_global(addr, bytes);
3556 }
3557
3558 // The memory is committed
3559 MemTracker::record_virtual_memory_reserve_and_commit((address)addr, bytes, CALLER_PC);
3560 }
3561
3562 return addr;
3563 }
3564
3565 bool os::Linux::release_memory_special_shm(char* base, size_t bytes) {
3566 // detaching the SHM segment will also delete it, see reserve_memory_special_shm()
3567 return shmdt(base) == 0;
3568 }
3569
3570 bool os::Linux::release_memory_special_huge_tlbfs(char* base, size_t bytes) {
3571 return pd_release_memory(base, bytes);
3572 }
3573
3574 bool os::release_memory_special(char* base, size_t bytes) {
3575 bool res;
3576 if (MemTracker::tracking_level() > NMT_minimal) {
3577 Tracker tkr = MemTracker::get_virtual_memory_release_tracker();
3578 res = os::Linux::release_memory_special_impl(base, bytes);
3579 if (res) {
3580 tkr.record((address)base, bytes);
3581 }
3582
3583 } else {
3584 res = os::Linux::release_memory_special_impl(base, bytes);
3585 }
3586 return res;
3587 }
3588
3589 bool os::Linux::release_memory_special_impl(char* base, size_t bytes) {
3590 assert(UseLargePages, "only for large pages");
3591 bool res;
3592
3593 if (UseSHM) {
3594 res = os::Linux::release_memory_special_shm(base, bytes);
3595 } else {
3596 assert(UseHugeTLBFS, "must be");
3597 res = os::Linux::release_memory_special_huge_tlbfs(base, bytes);
3598 }
3599 return res;
3600 }
3601
3602 size_t os::large_page_size() {
3603 return _large_page_size;
3604 }
3605
3606 // With SysV SHM the entire memory region must be allocated as shared
3607 // memory.
3608 // HugeTLBFS allows application to commit large page memory on demand.
3609 // However, when committing memory with HugeTLBFS fails, the region
3610 // that was supposed to be committed will lose the old reservation
3611 // and allow other threads to steal that memory region. Because of this
3612 // behavior we can't commit HugeTLBFS memory.
3613 bool os::can_commit_large_page_memory() {
3614 return UseTransparentHugePages;
3615 }
3616
3617 bool os::can_execute_large_page_memory() {
3618 return UseTransparentHugePages || UseHugeTLBFS;
3619 }
3620
3621 // Reserve memory at an arbitrary address, only if that area is
3622 // available (and not reserved for something else).
3623
3624 char* os::pd_attempt_reserve_memory_at(size_t bytes, char* requested_addr) {
3625 const int max_tries = 10;
3626 char* base[max_tries];
3627 size_t size[max_tries];
3628 const size_t gap = 0x000000;
3629
3630 // Assert only that the size is a multiple of the page size, since
3631 // that's all that mmap requires, and since that's all we really know
3632 // about at this low abstraction level. If we need higher alignment,
3633 // we can either pass an alignment to this method or verify alignment
3634 // in one of the methods further up the call chain. See bug 5044738.
3635 assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block");
3636
3637 // Repeatedly allocate blocks until the block is allocated at the
3638 // right spot. Give up after max_tries. Note that reserve_memory() will
3639 // automatically update _highest_vm_reserved_address if the call is
3640 // successful. The variable tracks the highest memory address every reserved
3641 // by JVM. It is used to detect heap-stack collision if running with
3642 // fixed-stack LinuxThreads. Because here we may attempt to reserve more
3643 // space than needed, it could confuse the collision detecting code. To
3644 // solve the problem, save current _highest_vm_reserved_address and
3645 // calculate the correct value before return.
3646 address old_highest = _highest_vm_reserved_address;
3647
3648 // Linux mmap allows caller to pass an address as hint; give it a try first,
3649 // if kernel honors the hint then we can return immediately.
3650 char * addr = anon_mmap(requested_addr, bytes, false);
3651 if (addr == requested_addr) {
3652 return requested_addr;
3653 }
3654
3655 if (addr != NULL) {
3656 // mmap() is successful but it fails to reserve at the requested address
3657 anon_munmap(addr, bytes);
3658 }
3659
3660 int i;
3661 for (i = 0; i < max_tries; ++i) {
3662 base[i] = reserve_memory(bytes);
3663
3664 if (base[i] != NULL) {
3665 // Is this the block we wanted?
3666 if (base[i] == requested_addr) {
3667 size[i] = bytes;
3668 break;
3669 }
3670
3671 // Does this overlap the block we wanted? Give back the overlapped
3672 // parts and try again.
3673
3674 size_t top_overlap = requested_addr + (bytes + gap) - base[i];
3675 if (top_overlap >= 0 && top_overlap < bytes) {
3676 unmap_memory(base[i], top_overlap);
3677 base[i] += top_overlap;
3678 size[i] = bytes - top_overlap;
3679 } else {
3680 size_t bottom_overlap = base[i] + bytes - requested_addr;
3681 if (bottom_overlap >= 0 && bottom_overlap < bytes) {
3682 unmap_memory(requested_addr, bottom_overlap);
3683 size[i] = bytes - bottom_overlap;
3684 } else {
3685 size[i] = bytes;
3686 }
3687 }
3688 }
3689 }
3690
3691 // Give back the unused reserved pieces.
3692
3693 for (int j = 0; j < i; ++j) {
3694 if (base[j] != NULL) {
3695 unmap_memory(base[j], size[j]);
3696 }
3697 }
3698
3699 if (i < max_tries) {
3700 _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes);
3701 return requested_addr;
3702 } else {
3703 _highest_vm_reserved_address = old_highest;
3704 return NULL;
3705 }
3706 }
3707
3708 size_t os::read(int fd, void *buf, unsigned int nBytes) {
3709 return ::read(fd, buf, nBytes);
3710 }
3711
3712 // TODO-FIXME: reconcile Solaris' os::sleep with the linux variation.
3713 // Solaris uses poll(), linux uses park().
3714 // Poll() is likely a better choice, assuming that Thread.interrupt()
3715 // generates a SIGUSRx signal. Note that SIGUSR1 can interfere with
3716 // SIGSEGV, see 4355769.
3717
3718 int os::sleep(Thread* thread, jlong millis, bool interruptible) {
3719 assert(thread == Thread::current(), "thread consistency check");
3720
3721 ParkEvent * const slp = thread->_SleepEvent ;
3722 slp->reset() ;
3723 OrderAccess::fence() ;
3724
3725 if (interruptible) {
3726 jlong prevtime = javaTimeNanos();
3727
3728 for (;;) {
3729 if (os::is_interrupted(thread, true)) {
3730 return OS_INTRPT;
3731 }
3732
3733 jlong newtime = javaTimeNanos();
3734
3735 if (newtime - prevtime < 0) {
3736 // time moving backwards, should only happen if no monotonic clock
3737 // not a guarantee() because JVM should not abort on kernel/glibc bugs
3738 assert(!Linux::supports_monotonic_clock(), "time moving backwards");
3739 } else {
3740 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC;
3741 }
3742
3743 if(millis <= 0) {
3744 return OS_OK;
3745 }
3746
3747 prevtime = newtime;
3748
3749 {
3750 assert(thread->is_Java_thread(), "sanity check");
3751 JavaThread *jt = (JavaThread *) thread;
3752 ThreadBlockInVM tbivm(jt);
3753 OSThreadWaitState osts(jt->osthread(), false /* not Object.wait() */);
3754
3755 jt->set_suspend_equivalent();
3756 // cleared by handle_special_suspend_equivalent_condition() or
3757 // java_suspend_self() via check_and_wait_while_suspended()
3758
3759 slp->park(millis);
3760
3761 // were we externally suspended while we were waiting?
3762 jt->check_and_wait_while_suspended();
3763 }
3764 }
3765 } else {
3766 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */);
3767 jlong prevtime = javaTimeNanos();
3768
3769 for (;;) {
3770 // It'd be nice to avoid the back-to-back javaTimeNanos() calls on
3771 // the 1st iteration ...
3772 jlong newtime = javaTimeNanos();
3773
3774 if (newtime - prevtime < 0) {
3775 // time moving backwards, should only happen if no monotonic clock
3776 // not a guarantee() because JVM should not abort on kernel/glibc bugs
3777 assert(!Linux::supports_monotonic_clock(), "time moving backwards");
3778 } else {
3779 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC;
3780 }
3781
3782 if(millis <= 0) break ;
3783
3784 prevtime = newtime;
3785 slp->park(millis);
3786 }
3787 return OS_OK ;
3788 }
3789 }
3790
3791 //
3792 // Short sleep, direct OS call.
3793 //
3794 // Note: certain versions of Linux CFS scheduler (since 2.6.23) do not guarantee
3795 // sched_yield(2) will actually give up the CPU:
3796 //
3797 // * Alone on this pariticular CPU, keeps running.
3798 // * Before the introduction of "skip_buddy" with "compat_yield" disabled
3799 // (pre 2.6.39).
3800 //
3801 // So calling this with 0 is an alternative.
3802 //
3803 void os::naked_short_sleep(jlong ms) {
3804 struct timespec req;
3805
3806 assert(ms < 1000, "Un-interruptable sleep, short time use only");
3807 req.tv_sec = 0;
3808 if (ms > 0) {
3809 req.tv_nsec = (ms % 1000) * 1000000;
3810 }
3811 else {
3812 req.tv_nsec = 1;
3813 }
3814
3815 nanosleep(&req, NULL);
3816
3817 return;
3818 }
3819
3820 // Sleep forever; naked call to OS-specific sleep; use with CAUTION
3821 void os::infinite_sleep() {
3822 while (true) { // sleep forever ...
3823 ::sleep(100); // ... 100 seconds at a time
3824 }
3825 }
3826
3827 // Used to convert frequent JVM_Yield() to nops
3828 bool os::dont_yield() {
3829 return DontYieldALot;
3830 }
3831
3832 void os::yield() {
3833 sched_yield();
3834 }
3835
3836 os::YieldResult os::NakedYield() { sched_yield(); return os::YIELD_UNKNOWN ;}
3837
3838 void os::yield_all(int attempts) {
3839 // Yields to all threads, including threads with lower priorities
3840 // Threads on Linux are all with same priority. The Solaris style
3841 // os::yield_all() with nanosleep(1ms) is not necessary.
3842 sched_yield();
3843 }
3844
3845 // Called from the tight loops to possibly influence time-sharing heuristics
3846 void os::loop_breaker(int attempts) {
3847 os::yield_all(attempts);
3848 }
3849
3850 ////////////////////////////////////////////////////////////////////////////////
3851 // thread priority support
3852
3853 // Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER
3854 // only supports dynamic priority, static priority must be zero. For real-time
3855 // applications, Linux supports SCHED_RR which allows static priority (1-99).
3856 // However, for large multi-threaded applications, SCHED_RR is not only slower
3857 // than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out
3858 // of 5 runs - Sep 2005).
3859 //
3860 // The following code actually changes the niceness of kernel-thread/LWP. It
3861 // has an assumption that setpriority() only modifies one kernel-thread/LWP,
3862 // not the entire user process, and user level threads are 1:1 mapped to kernel
3863 // threads. It has always been the case, but could change in the future. For
3864 // this reason, the code should not be used as default (ThreadPriorityPolicy=0).
3865 // It is only used when ThreadPriorityPolicy=1 and requires root privilege.
3866
3867 int os::java_to_os_priority[CriticalPriority + 1] = {
3868 19, // 0 Entry should never be used
3869
3870 4, // 1 MinPriority
3871 3, // 2
3872 2, // 3
3873
3874 1, // 4
3875 0, // 5 NormPriority
3876 -1, // 6
3877
3878 -2, // 7
3879 -3, // 8
3880 -4, // 9 NearMaxPriority
3881
3882 -5, // 10 MaxPriority
3883
3884 -5 // 11 CriticalPriority
3885 };
3886
3887 static int prio_init() {
3888 if (ThreadPriorityPolicy == 1) {
3889 // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1
3890 // if effective uid is not root. Perhaps, a more elegant way of doing
3891 // this is to test CAP_SYS_NICE capability, but that will require libcap.so
3892 if (geteuid() != 0) {
3893 if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) {
3894 warning("-XX:ThreadPriorityPolicy requires root privilege on Linux");
3895 }
3896 ThreadPriorityPolicy = 0;
3897 }
3898 }
3899 if (UseCriticalJavaThreadPriority) {
3900 os::java_to_os_priority[MaxPriority] = os::java_to_os_priority[CriticalPriority];
3901 }
3902 return 0;
3903 }
3904
3905 OSReturn os::set_native_priority(Thread* thread, int newpri) {
3906 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) return OS_OK;
3907
3908 int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri);
3909 return (ret == 0) ? OS_OK : OS_ERR;
3910 }
3911
3912 OSReturn os::get_native_priority(const Thread* const thread, int *priority_ptr) {
3913 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) {
3914 *priority_ptr = java_to_os_priority[NormPriority];
3915 return OS_OK;
3916 }
3917
3918 errno = 0;
3919 *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id());
3920 return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR);
3921 }
3922
3923 // Hint to the underlying OS that a task switch would not be good.
3924 // Void return because it's a hint and can fail.
3925 void os::hint_no_preempt() {}
3926
3927 ////////////////////////////////////////////////////////////////////////////////
3928 // suspend/resume support
3929
3930 // the low-level signal-based suspend/resume support is a remnant from the
3931 // old VM-suspension that used to be for java-suspension, safepoints etc,
3932 // within hotspot. Now there is a single use-case for this:
3933 // - calling get_thread_pc() on the VMThread by the flat-profiler task
3934 // that runs in the watcher thread.
3935 // The remaining code is greatly simplified from the more general suspension
3936 // code that used to be used.
3937 //
3938 // The protocol is quite simple:
3939 // - suspend:
3940 // - sends a signal to the target thread
3941 // - polls the suspend state of the osthread using a yield loop
3942 // - target thread signal handler (SR_handler) sets suspend state
3943 // and blocks in sigsuspend until continued
3944 // - resume:
3945 // - sets target osthread state to continue
3946 // - sends signal to end the sigsuspend loop in the SR_handler
3947 //
3948 // Note that the SR_lock plays no role in this suspend/resume protocol.
3949 //
3950
3951 static void resume_clear_context(OSThread *osthread) {
3952 osthread->set_ucontext(NULL);
3953 osthread->set_siginfo(NULL);
3954 }
3955
3956 static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo, ucontext_t* context) {
3957 osthread->set_ucontext(context);
3958 osthread->set_siginfo(siginfo);
3959 }
3960
3961 //
3962 // Handler function invoked when a thread's execution is suspended or
3963 // resumed. We have to be careful that only async-safe functions are
3964 // called here (Note: most pthread functions are not async safe and
3965 // should be avoided.)
3966 //
3967 // Note: sigwait() is a more natural fit than sigsuspend() from an
3968 // interface point of view, but sigwait() prevents the signal hander
3969 // from being run. libpthread would get very confused by not having
3970 // its signal handlers run and prevents sigwait()'s use with the
3971 // mutex granting granting signal.
3972 //
3973 // Currently only ever called on the VMThread and JavaThreads (PC sampling)
3974 //
3975 static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) {
3976 // Save and restore errno to avoid confusing native code with EINTR
3977 // after sigsuspend.
3978 int old_errno = errno;
3979
3980 Thread* thread = Thread::current();
3981 OSThread* osthread = thread->osthread();
3982 assert(thread->is_VM_thread() || thread->is_Java_thread(), "Must be VMThread or JavaThread");
3983
3984 os::SuspendResume::State current = osthread->sr.state();
3985 if (current == os::SuspendResume::SR_SUSPEND_REQUEST) {
3986 suspend_save_context(osthread, siginfo, context);
3987
3988 // attempt to switch the state, we assume we had a SUSPEND_REQUEST
3989 os::SuspendResume::State state = osthread->sr.suspended();
3990 if (state == os::SuspendResume::SR_SUSPENDED) {
3991 sigset_t suspend_set; // signals for sigsuspend()
3992
3993 // get current set of blocked signals and unblock resume signal
3994 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set);
3995 sigdelset(&suspend_set, SR_signum);
3996
3997 sr_semaphore.signal();
3998 // wait here until we are resumed
3999 while (1) {
4000 sigsuspend(&suspend_set);
4001
4002 os::SuspendResume::State result = osthread->sr.running();
4003 if (result == os::SuspendResume::SR_RUNNING) {
4004 sr_semaphore.signal();
4005 break;
4006 }
4007 }
4008
4009 } else if (state == os::SuspendResume::SR_RUNNING) {
4010 // request was cancelled, continue
4011 } else {
4012 ShouldNotReachHere();
4013 }
4014
4015 resume_clear_context(osthread);
4016 } else if (current == os::SuspendResume::SR_RUNNING) {
4017 // request was cancelled, continue
4018 } else if (current == os::SuspendResume::SR_WAKEUP_REQUEST) {
4019 // ignore
4020 } else {
4021 // ignore
4022 }
4023
4024 errno = old_errno;
4025 }
4026
4027
4028 static int SR_initialize() {
4029 struct sigaction act;
4030 char *s;
4031 /* Get signal number to use for suspend/resume */
4032 if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) {
4033 int sig = ::strtol(s, 0, 10);
4034 if (sig > 0 || sig < _NSIG) {
4035 SR_signum = sig;
4036 }
4037 }
4038
4039 assert(SR_signum > SIGSEGV && SR_signum > SIGBUS,
4040 "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769");
4041
4042 sigemptyset(&SR_sigset);
4043 sigaddset(&SR_sigset, SR_signum);
4044
4045 /* Set up signal handler for suspend/resume */
4046 act.sa_flags = SA_RESTART|SA_SIGINFO;
4047 act.sa_handler = (void (*)(int)) SR_handler;
4048
4049 // SR_signum is blocked by default.
4050 // 4528190 - We also need to block pthread restart signal (32 on all
4051 // supported Linux platforms). Note that LinuxThreads need to block
4052 // this signal for all threads to work properly. So we don't have
4053 // to use hard-coded signal number when setting up the mask.
4054 pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask);
4055
4056 if (sigaction(SR_signum, &act, 0) == -1) {
4057 return -1;
4058 }
4059
4060 // Save signal flag
4061 os::Linux::set_our_sigflags(SR_signum, act.sa_flags);
4062 return 0;
4063 }
4064
4065 static int sr_notify(OSThread* osthread) {
4066 int status = pthread_kill(osthread->pthread_id(), SR_signum);
4067 assert_status(status == 0, status, "pthread_kill");
4068 return status;
4069 }
4070
4071 // "Randomly" selected value for how long we want to spin
4072 // before bailing out on suspending a thread, also how often
4073 // we send a signal to a thread we want to resume
4074 static const int RANDOMLY_LARGE_INTEGER = 1000000;
4075 static const int RANDOMLY_LARGE_INTEGER2 = 100;
4076
4077 // returns true on success and false on error - really an error is fatal
4078 // but this seems the normal response to library errors
4079 static bool do_suspend(OSThread* osthread) {
4080 assert(osthread->sr.is_running(), "thread should be running");
4081 assert(!sr_semaphore.trywait(), "semaphore has invalid state");
4082
4083 // mark as suspended and send signal
4084 if (osthread->sr.request_suspend() != os::SuspendResume::SR_SUSPEND_REQUEST) {
4085 // failed to switch, state wasn't running?
4086 ShouldNotReachHere();
4087 return false;
4088 }
4089
4090 if (sr_notify(osthread) != 0) {
4091 ShouldNotReachHere();
4092 }
4093
4094 // managed to send the signal and switch to SUSPEND_REQUEST, now wait for SUSPENDED
4095 while (true) {
4096 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) {
4097 break;
4098 } else {
4099 // timeout
4100 os::SuspendResume::State cancelled = osthread->sr.cancel_suspend();
4101 if (cancelled == os::SuspendResume::SR_RUNNING) {
4102 return false;
4103 } else if (cancelled == os::SuspendResume::SR_SUSPENDED) {
4104 // make sure that we consume the signal on the semaphore as well
4105 sr_semaphore.wait();
4106 break;
4107 } else {
4108 ShouldNotReachHere();
4109 return false;
4110 }
4111 }
4112 }
4113
4114 guarantee(osthread->sr.is_suspended(), "Must be suspended");
4115 return true;
4116 }
4117
4118 static void do_resume(OSThread* osthread) {
4119 assert(osthread->sr.is_suspended(), "thread should be suspended");
4120 assert(!sr_semaphore.trywait(), "invalid semaphore state");
4121
4122 if (osthread->sr.request_wakeup() != os::SuspendResume::SR_WAKEUP_REQUEST) {
4123 // failed to switch to WAKEUP_REQUEST
4124 ShouldNotReachHere();
4125 return;
4126 }
4127
4128 while (true) {
4129 if (sr_notify(osthread) == 0) {
4130 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) {
4131 if (osthread->sr.is_running()) {
4132 return;
4133 }
4134 }
4135 } else {
4136 ShouldNotReachHere();
4137 }
4138 }
4139
4140 guarantee(osthread->sr.is_running(), "Must be running!");
4141 }
4142
4143 ////////////////////////////////////////////////////////////////////////////////
4144 // interrupt support
4145
4146 void os::interrupt(Thread* thread) {
4147 assert(Thread::current() == thread || Threads_lock->owned_by_self(),
4148 "possibility of dangling Thread pointer");
4149
4150 OSThread* osthread = thread->osthread();
4151
4152 if (!osthread->interrupted()) {
4153 osthread->set_interrupted(true);
4154 // More than one thread can get here with the same value of osthread,
4155 // resulting in multiple notifications. We do, however, want the store
4156 // to interrupted() to be visible to other threads before we execute unpark().
4157 OrderAccess::fence();
4158 ParkEvent * const slp = thread->_SleepEvent ;
4159 if (slp != NULL) slp->unpark() ;
4160 }
4161
4162 // For JSR166. Unpark even if interrupt status already was set
4163 if (thread->is_Java_thread())
4164 ((JavaThread*)thread)->parker()->unpark();
4165
4166 ParkEvent * ev = thread->_ParkEvent ;
4167 if (ev != NULL) ev->unpark() ;
4168
4169 }
4170
4171 bool os::is_interrupted(Thread* thread, bool clear_interrupted) {
4172 assert(Thread::current() == thread || Threads_lock->owned_by_self(),
4173 "possibility of dangling Thread pointer");
4174
4175 OSThread* osthread = thread->osthread();
4176
4177 bool interrupted = osthread->interrupted();
4178
4179 if (interrupted && clear_interrupted) {
4180 osthread->set_interrupted(false);
4181 // consider thread->_SleepEvent->reset() ... optional optimization
4182 }
4183
4184 return interrupted;
4185 }
4186
4187 ///////////////////////////////////////////////////////////////////////////////////
4188 // signal handling (except suspend/resume)
4189
4190 // This routine may be used by user applications as a "hook" to catch signals.
4191 // The user-defined signal handler must pass unrecognized signals to this
4192 // routine, and if it returns true (non-zero), then the signal handler must
4193 // return immediately. If the flag "abort_if_unrecognized" is true, then this
4194 // routine will never retun false (zero), but instead will execute a VM panic
4195 // routine kill the process.
4196 //
4197 // If this routine returns false, it is OK to call it again. This allows
4198 // the user-defined signal handler to perform checks either before or after
4199 // the VM performs its own checks. Naturally, the user code would be making
4200 // a serious error if it tried to handle an exception (such as a null check
4201 // or breakpoint) that the VM was generating for its own correct operation.
4202 //
4203 // This routine may recognize any of the following kinds of signals:
4204 // SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1.
4205 // It should be consulted by handlers for any of those signals.
4206 //
4207 // The caller of this routine must pass in the three arguments supplied
4208 // to the function referred to in the "sa_sigaction" (not the "sa_handler")
4209 // field of the structure passed to sigaction(). This routine assumes that
4210 // the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART.
4211 //
4212 // Note that the VM will print warnings if it detects conflicting signal
4213 // handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers".
4214 //
4215 extern "C" JNIEXPORT int
4216 JVM_handle_linux_signal(int signo, siginfo_t* siginfo,
4217 void* ucontext, int abort_if_unrecognized);
4218
4219 void signalHandler(int sig, siginfo_t* info, void* uc) {
4220 assert(info != NULL && uc != NULL, "it must be old kernel");
4221 int orig_errno = errno; // Preserve errno value over signal handler.
4222 JVM_handle_linux_signal(sig, info, uc, true);
4223 errno = orig_errno;
4224 }
4225
4226
4227 // This boolean allows users to forward their own non-matching signals
4228 // to JVM_handle_linux_signal, harmlessly.
4229 bool os::Linux::signal_handlers_are_installed = false;
4230
4231 // For signal-chaining
4232 struct sigaction os::Linux::sigact[MAXSIGNUM];
4233 unsigned int os::Linux::sigs = 0;
4234 bool os::Linux::libjsig_is_loaded = false;
4235 typedef struct sigaction *(*get_signal_t)(int);
4236 get_signal_t os::Linux::get_signal_action = NULL;
4237
4238 struct sigaction* os::Linux::get_chained_signal_action(int sig) {
4239 struct sigaction *actp = NULL;
4240
4241 if (libjsig_is_loaded) {
4242 // Retrieve the old signal handler from libjsig
4243 actp = (*get_signal_action)(sig);
4244 }
4245 if (actp == NULL) {
4246 // Retrieve the preinstalled signal handler from jvm
4247 actp = get_preinstalled_handler(sig);
4248 }
4249
4250 return actp;
4251 }
4252
4253 static bool call_chained_handler(struct sigaction *actp, int sig,
4254 siginfo_t *siginfo, void *context) {
4255 // Call the old signal handler
4256 if (actp->sa_handler == SIG_DFL) {
4257 // It's more reasonable to let jvm treat it as an unexpected exception
4258 // instead of taking the default action.
4259 return false;
4260 } else if (actp->sa_handler != SIG_IGN) {
4261 if ((actp->sa_flags & SA_NODEFER) == 0) {
4262 // automaticlly block the signal
4263 sigaddset(&(actp->sa_mask), sig);
4264 }
4265
4266 sa_handler_t hand;
4267 sa_sigaction_t sa;
4268 bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0;
4269 // retrieve the chained handler
4270 if (siginfo_flag_set) {
4271 sa = actp->sa_sigaction;
4272 } else {
4273 hand = actp->sa_handler;
4274 }
4275
4276 if ((actp->sa_flags & SA_RESETHAND) != 0) {
4277 actp->sa_handler = SIG_DFL;
4278 }
4279
4280 // try to honor the signal mask
4281 sigset_t oset;
4282 pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset);
4283
4284 // call into the chained handler
4285 if (siginfo_flag_set) {
4286 (*sa)(sig, siginfo, context);
4287 } else {
4288 (*hand)(sig);
4289 }
4290
4291 // restore the signal mask
4292 pthread_sigmask(SIG_SETMASK, &oset, 0);
4293 }
4294 // Tell jvm's signal handler the signal is taken care of.
4295 return true;
4296 }
4297
4298 bool os::Linux::chained_handler(int sig, siginfo_t* siginfo, void* context) {
4299 bool chained = false;
4300 // signal-chaining
4301 if (UseSignalChaining) {
4302 struct sigaction *actp = get_chained_signal_action(sig);
4303 if (actp != NULL) {
4304 chained = call_chained_handler(actp, sig, siginfo, context);
4305 }
4306 }
4307 return chained;
4308 }
4309
4310 struct sigaction* os::Linux::get_preinstalled_handler(int sig) {
4311 if ((( (unsigned int)1 << sig ) & sigs) != 0) {
4312 return &sigact[sig];
4313 }
4314 return NULL;
4315 }
4316
4317 void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) {
4318 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4319 sigact[sig] = oldAct;
4320 sigs |= (unsigned int)1 << sig;
4321 }
4322
4323 // for diagnostic
4324 int os::Linux::sigflags[MAXSIGNUM];
4325
4326 int os::Linux::get_our_sigflags(int sig) {
4327 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4328 return sigflags[sig];
4329 }
4330
4331 void os::Linux::set_our_sigflags(int sig, int flags) {
4332 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4333 sigflags[sig] = flags;
4334 }
4335
4336 void os::Linux::set_signal_handler(int sig, bool set_installed) {
4337 // Check for overwrite.
4338 struct sigaction oldAct;
4339 sigaction(sig, (struct sigaction*)NULL, &oldAct);
4340
4341 void* oldhand = oldAct.sa_sigaction
4342 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction)
4343 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler);
4344 if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) &&
4345 oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) &&
4346 oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) {
4347 if (AllowUserSignalHandlers || !set_installed) {
4348 // Do not overwrite; user takes responsibility to forward to us.
4349 return;
4350 } else if (UseSignalChaining) {
4351 // save the old handler in jvm
4352 save_preinstalled_handler(sig, oldAct);
4353 // libjsig also interposes the sigaction() call below and saves the
4354 // old sigaction on it own.
4355 } else {
4356 fatal(err_msg("Encountered unexpected pre-existing sigaction handler "
4357 "%#lx for signal %d.", (long)oldhand, sig));
4358 }
4359 }
4360
4361 struct sigaction sigAct;
4362 sigfillset(&(sigAct.sa_mask));
4363 sigAct.sa_handler = SIG_DFL;
4364 if (!set_installed) {
4365 sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
4366 } else {
4367 sigAct.sa_sigaction = signalHandler;
4368 sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
4369 }
4370 // Save flags, which are set by ours
4371 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4372 sigflags[sig] = sigAct.sa_flags;
4373
4374 int ret = sigaction(sig, &sigAct, &oldAct);
4375 assert(ret == 0, "check");
4376
4377 void* oldhand2 = oldAct.sa_sigaction
4378 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction)
4379 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler);
4380 assert(oldhand2 == oldhand, "no concurrent signal handler installation");
4381 }
4382
4383 // install signal handlers for signals that HotSpot needs to
4384 // handle in order to support Java-level exception handling.
4385
4386 void os::Linux::install_signal_handlers() {
4387 if (!signal_handlers_are_installed) {
4388 signal_handlers_are_installed = true;
4389
4390 // signal-chaining
4391 typedef void (*signal_setting_t)();
4392 signal_setting_t begin_signal_setting = NULL;
4393 signal_setting_t end_signal_setting = NULL;
4394 begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
4395 dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting"));
4396 if (begin_signal_setting != NULL) {
4397 end_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
4398 dlsym(RTLD_DEFAULT, "JVM_end_signal_setting"));
4399 get_signal_action = CAST_TO_FN_PTR(get_signal_t,
4400 dlsym(RTLD_DEFAULT, "JVM_get_signal_action"));
4401 libjsig_is_loaded = true;
4402 assert(UseSignalChaining, "should enable signal-chaining");
4403 }
4404 if (libjsig_is_loaded) {
4405 // Tell libjsig jvm is setting signal handlers
4406 (*begin_signal_setting)();
4407 }
4408
4409 set_signal_handler(SIGSEGV, true);
4410 set_signal_handler(SIGPIPE, true);
4411 set_signal_handler(SIGBUS, true);
4412 set_signal_handler(SIGILL, true);
4413 set_signal_handler(SIGFPE, true);
4414 #if defined(PPC64)
4415 set_signal_handler(SIGTRAP, true);
4416 #endif
4417 set_signal_handler(SIGXFSZ, true);
4418
4419 if (libjsig_is_loaded) {
4420 // Tell libjsig jvm finishes setting signal handlers
4421 (*end_signal_setting)();
4422 }
4423
4424 // We don't activate signal checker if libjsig is in place, we trust ourselves
4425 // and if UserSignalHandler is installed all bets are off.
4426 // Log that signal checking is off only if -verbose:jni is specified.
4427 if (CheckJNICalls) {
4428 if (libjsig_is_loaded) {
4429 if (PrintJNIResolving) {
4430 tty->print_cr("Info: libjsig is activated, all active signal checking is disabled");
4431 }
4432 check_signals = false;
4433 }
4434 if (AllowUserSignalHandlers) {
4435 if (PrintJNIResolving) {
4436 tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled");
4437 }
4438 check_signals = false;
4439 }
4440 }
4441 }
4442 }
4443
4444 // This is the fastest way to get thread cpu time on Linux.
4445 // Returns cpu time (user+sys) for any thread, not only for current.
4446 // POSIX compliant clocks are implemented in the kernels 2.6.16+.
4447 // It might work on 2.6.10+ with a special kernel/glibc patch.
4448 // For reference, please, see IEEE Std 1003.1-2004:
4449 // http://www.unix.org/single_unix_specification
4450
4451 jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) {
4452 struct timespec tp;
4453 int rc = os::Linux::clock_gettime(clockid, &tp);
4454 assert(rc == 0, "clock_gettime is expected to return 0 code");
4455
4456 return (tp.tv_sec * NANOSECS_PER_SEC) + tp.tv_nsec;
4457 }
4458
4459 /////
4460 // glibc on Linux platform uses non-documented flag
4461 // to indicate, that some special sort of signal
4462 // trampoline is used.
4463 // We will never set this flag, and we should
4464 // ignore this flag in our diagnostic
4465 #ifdef SIGNIFICANT_SIGNAL_MASK
4466 #undef SIGNIFICANT_SIGNAL_MASK
4467 #endif
4468 #define SIGNIFICANT_SIGNAL_MASK (~0x04000000)
4469
4470 static const char* get_signal_handler_name(address handler,
4471 char* buf, int buflen) {
4472 int offset;
4473 bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset);
4474 if (found) {
4475 // skip directory names
4476 const char *p1, *p2;
4477 p1 = buf;
4478 size_t len = strlen(os::file_separator());
4479 while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len;
4480 jio_snprintf(buf, buflen, "%s+0x%x", p1, offset);
4481 } else {
4482 jio_snprintf(buf, buflen, PTR_FORMAT, handler);
4483 }
4484 return buf;
4485 }
4486
4487 static void print_signal_handler(outputStream* st, int sig,
4488 char* buf, size_t buflen) {
4489 struct sigaction sa;
4490
4491 sigaction(sig, NULL, &sa);
4492
4493 // See comment for SIGNIFICANT_SIGNAL_MASK define
4494 sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
4495
4496 st->print("%s: ", os::exception_name(sig, buf, buflen));
4497
4498 address handler = (sa.sa_flags & SA_SIGINFO)
4499 ? CAST_FROM_FN_PTR(address, sa.sa_sigaction)
4500 : CAST_FROM_FN_PTR(address, sa.sa_handler);
4501
4502 if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) {
4503 st->print("SIG_DFL");
4504 } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) {
4505 st->print("SIG_IGN");
4506 } else {
4507 st->print("[%s]", get_signal_handler_name(handler, buf, buflen));
4508 }
4509
4510 st->print(", sa_mask[0]=");
4511 os::Posix::print_signal_set_short(st, &sa.sa_mask);
4512
4513 address rh = VMError::get_resetted_sighandler(sig);
4514 // May be, handler was resetted by VMError?
4515 if(rh != NULL) {
4516 handler = rh;
4517 sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK;
4518 }
4519
4520 st->print(", sa_flags=");
4521 os::Posix::print_sa_flags(st, sa.sa_flags);
4522
4523 // Check: is it our handler?
4524 if(handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) ||
4525 handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) {
4526 // It is our signal handler
4527 // check for flags, reset system-used one!
4528 if((int)sa.sa_flags != os::Linux::get_our_sigflags(sig)) {
4529 st->print(
4530 ", flags was changed from " PTR32_FORMAT ", consider using jsig library",
4531 os::Linux::get_our_sigflags(sig));
4532 }
4533 }
4534 st->cr();
4535 }
4536
4537
4538 #define DO_SIGNAL_CHECK(sig) \
4539 if (!sigismember(&check_signal_done, sig)) \
4540 os::Linux::check_signal_handler(sig)
4541
4542 // This method is a periodic task to check for misbehaving JNI applications
4543 // under CheckJNI, we can add any periodic checks here
4544
4545 void os::run_periodic_checks() {
4546
4547 if (check_signals == false) return;
4548
4549 // SEGV and BUS if overridden could potentially prevent
4550 // generation of hs*.log in the event of a crash, debugging
4551 // such a case can be very challenging, so we absolutely
4552 // check the following for a good measure:
4553 DO_SIGNAL_CHECK(SIGSEGV);
4554 DO_SIGNAL_CHECK(SIGILL);
4555 DO_SIGNAL_CHECK(SIGFPE);
4556 DO_SIGNAL_CHECK(SIGBUS);
4557 DO_SIGNAL_CHECK(SIGPIPE);
4558 DO_SIGNAL_CHECK(SIGXFSZ);
4559 #if defined(PPC64)
4560 DO_SIGNAL_CHECK(SIGTRAP);
4561 #endif
4562
4563 // ReduceSignalUsage allows the user to override these handlers
4564 // see comments at the very top and jvm_solaris.h
4565 if (!ReduceSignalUsage) {
4566 DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL);
4567 DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL);
4568 DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL);
4569 DO_SIGNAL_CHECK(BREAK_SIGNAL);
4570 }
4571
4572 DO_SIGNAL_CHECK(SR_signum);
4573 DO_SIGNAL_CHECK(INTERRUPT_SIGNAL);
4574 }
4575
4576 typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *);
4577
4578 static os_sigaction_t os_sigaction = NULL;
4579
4580 void os::Linux::check_signal_handler(int sig) {
4581 char buf[O_BUFLEN];
4582 address jvmHandler = NULL;
4583
4584
4585 struct sigaction act;
4586 if (os_sigaction == NULL) {
4587 // only trust the default sigaction, in case it has been interposed
4588 os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction");
4589 if (os_sigaction == NULL) return;
4590 }
4591
4592 os_sigaction(sig, (struct sigaction*)NULL, &act);
4593
4594
4595 act.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
4596
4597 address thisHandler = (act.sa_flags & SA_SIGINFO)
4598 ? CAST_FROM_FN_PTR(address, act.sa_sigaction)
4599 : CAST_FROM_FN_PTR(address, act.sa_handler) ;
4600
4601
4602 switch(sig) {
4603 case SIGSEGV:
4604 case SIGBUS:
4605 case SIGFPE:
4606 case SIGPIPE:
4607 case SIGILL:
4608 case SIGXFSZ:
4609 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler);
4610 break;
4611
4612 case SHUTDOWN1_SIGNAL:
4613 case SHUTDOWN2_SIGNAL:
4614 case SHUTDOWN3_SIGNAL:
4615 case BREAK_SIGNAL:
4616 jvmHandler = (address)user_handler();
4617 break;
4618
4619 case INTERRUPT_SIGNAL:
4620 jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL);
4621 break;
4622
4623 default:
4624 if (sig == SR_signum) {
4625 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler);
4626 } else {
4627 return;
4628 }
4629 break;
4630 }
4631
4632 if (thisHandler != jvmHandler) {
4633 tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN));
4634 tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN));
4635 tty->print_cr(" found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN));
4636 // No need to check this sig any longer
4637 sigaddset(&check_signal_done, sig);
4638 } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) {
4639 tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN));
4640 tty->print("expected:" PTR32_FORMAT, os::Linux::get_our_sigflags(sig));
4641 tty->print_cr(" found:" PTR32_FORMAT, act.sa_flags);
4642 // No need to check this sig any longer
4643 sigaddset(&check_signal_done, sig);
4644 }
4645
4646 // Dump all the signal
4647 if (sigismember(&check_signal_done, sig)) {
4648 print_signal_handlers(tty, buf, O_BUFLEN);
4649 }
4650 }
4651
4652 extern void report_error(char* file_name, int line_no, char* title, char* format, ...);
4653
4654 extern bool signal_name(int signo, char* buf, size_t len);
4655
4656 const char* os::exception_name(int exception_code, char* buf, size_t size) {
4657 if (0 < exception_code && exception_code <= SIGRTMAX) {
4658 // signal
4659 if (!signal_name(exception_code, buf, size)) {
4660 jio_snprintf(buf, size, "SIG%d", exception_code);
4661 }
4662 return buf;
4663 } else {
4664 return NULL;
4665 }
4666 }
4667
4668 // this is called _before_ the most of global arguments have been parsed
4669 void os::init(void) {
4670 char dummy; /* used to get a guess on initial stack address */
4671 // first_hrtime = gethrtime();
4672
4673 // With LinuxThreads the JavaMain thread pid (primordial thread)
4674 // is different than the pid of the java launcher thread.
4675 // So, on Linux, the launcher thread pid is passed to the VM
4676 // via the sun.java.launcher.pid property.
4677 // Use this property instead of getpid() if it was correctly passed.
4678 // See bug 6351349.
4679 pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid();
4680
4681 _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid();
4682
4683 clock_tics_per_sec = sysconf(_SC_CLK_TCK);
4684
4685 init_random(1234567);
4686
4687 ThreadCritical::initialize();
4688
4689 Linux::set_page_size(sysconf(_SC_PAGESIZE));
4690 if (Linux::page_size() == -1) {
4691 fatal(err_msg("os_linux.cpp: os::init: sysconf failed (%s)",
4692 strerror(errno)));
4693 }
4694 init_page_sizes((size_t) Linux::page_size());
4695
4696 Linux::initialize_system_info();
4697
4698 // main_thread points to the aboriginal thread
4699 Linux::_main_thread = pthread_self();
4700
4701 Linux::clock_init();
4702 initial_time_count = javaTimeNanos();
4703
4704 // pthread_condattr initialization for monotonic clock
4705 int status;
4706 pthread_condattr_t* _condattr = os::Linux::condAttr();
4707 if ((status = pthread_condattr_init(_condattr)) != 0) {
4708 fatal(err_msg("pthread_condattr_init: %s", strerror(status)));
4709 }
4710 // Only set the clock if CLOCK_MONOTONIC is available
4711 if (Linux::supports_monotonic_clock()) {
4712 if ((status = pthread_condattr_setclock(_condattr, CLOCK_MONOTONIC)) != 0) {
4713 if (status == EINVAL) {
4714 warning("Unable to use monotonic clock with relative timed-waits" \
4715 " - changes to the time-of-day clock may have adverse affects");
4716 } else {
4717 fatal(err_msg("pthread_condattr_setclock: %s", strerror(status)));
4718 }
4719 }
4720 }
4721 // else it defaults to CLOCK_REALTIME
4722
4723 pthread_mutex_init(&dl_mutex, NULL);
4724
4725 // If the pagesize of the VM is greater than 8K determine the appropriate
4726 // number of initial guard pages. The user can change this with the
4727 // command line arguments, if needed.
4728 if (vm_page_size() > (int)Linux::vm_default_page_size()) {
4729 StackYellowPages = 1;
4730 StackRedPages = 1;
4731 StackShadowPages = round_to((StackShadowPages*Linux::vm_default_page_size()), vm_page_size()) / vm_page_size();
4732 }
4733 }
4734
4735 // To install functions for atexit system call
4736 extern "C" {
4737 static void perfMemory_exit_helper() {
4738 perfMemory_exit();
4739 }
4740 }
4741
4742 // this is called _after_ the global arguments have been parsed
4743 jint os::init_2(void)
4744 {
4745 Linux::fast_thread_clock_init();
4746
4747 // Allocate a single page and mark it as readable for safepoint polling
4748 address polling_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
4749 guarantee( polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page" );
4750
4751 os::set_polling_page( polling_page );
4752
4753 #ifndef PRODUCT
4754 if(Verbose && PrintMiscellaneous)
4755 tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n", (intptr_t)polling_page);
4756 #endif
4757
4758 if (!UseMembar) {
4759 address mem_serialize_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
4760 guarantee( mem_serialize_page != MAP_FAILED, "mmap Failed for memory serialize page");
4761 os::set_memory_serialize_page( mem_serialize_page );
4762
4763 #ifndef PRODUCT
4764 if(Verbose && PrintMiscellaneous)
4765 tty->print("[Memory Serialize Page address: " INTPTR_FORMAT "]\n", (intptr_t)mem_serialize_page);
4766 #endif
4767 }
4768
4769 // initialize suspend/resume support - must do this before signal_sets_init()
4770 if (SR_initialize() != 0) {
4771 perror("SR_initialize failed");
4772 return JNI_ERR;
4773 }
4774
4775 Linux::signal_sets_init();
4776 Linux::install_signal_handlers();
4777
4778 // Check minimum allowable stack size for thread creation and to initialize
4779 // the java system classes, including StackOverflowError - depends on page
4780 // size. Add a page for compiler2 recursion in main thread.
4781 // Add in 2*BytesPerWord times page size to account for VM stack during
4782 // class initialization depending on 32 or 64 bit VM.
4783 os::Linux::min_stack_allowed = MAX2(os::Linux::min_stack_allowed,
4784 (size_t)(StackYellowPages+StackRedPages+StackShadowPages) * Linux::page_size() +
4785 (2*BytesPerWord COMPILER2_PRESENT(+1)) * Linux::vm_default_page_size());
4786
4787 size_t threadStackSizeInBytes = ThreadStackSize * K;
4788 if (threadStackSizeInBytes != 0 &&
4789 threadStackSizeInBytes < os::Linux::min_stack_allowed) {
4790 tty->print_cr("\nThe stack size specified is too small, "
4791 "Specify at least %dk",
4792 os::Linux::min_stack_allowed/ K);
4793 return JNI_ERR;
4794 }
4795
4796 // Make the stack size a multiple of the page size so that
4797 // the yellow/red zones can be guarded.
4798 JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes,
4799 vm_page_size()));
4800
4801 Linux::capture_initial_stack(JavaThread::stack_size_at_create());
4802
4803 #if defined(IA32)
4804 workaround_expand_exec_shield_cs_limit();
4805 #endif
4806
4807 Linux::libpthread_init();
4808 if (PrintMiscellaneous && (Verbose || WizardMode)) {
4809 tty->print_cr("[HotSpot is running with %s, %s(%s)]\n",
4810 Linux::glibc_version(), Linux::libpthread_version(),
4811 Linux::is_floating_stack() ? "floating stack" : "fixed stack");
4812 }
4813
4814 if (UseNUMA) {
4815 if (!Linux::libnuma_init()) {
4816 UseNUMA = false;
4817 } else {
4818 if ((Linux::numa_max_node() < 1)) {
4819 // There's only one node(they start from 0), disable NUMA.
4820 UseNUMA = false;
4821 }
4822 }
4823 // With SHM and HugeTLBFS large pages we cannot uncommit a page, so there's no way
4824 // we can make the adaptive lgrp chunk resizing work. If the user specified
4825 // both UseNUMA and UseLargePages (or UseSHM/UseHugeTLBFS) on the command line - warn and
4826 // disable adaptive resizing.
4827 if (UseNUMA && UseLargePages && !can_commit_large_page_memory()) {
4828 if (FLAG_IS_DEFAULT(UseNUMA)) {
4829 UseNUMA = false;
4830 } else {
4831 if (FLAG_IS_DEFAULT(UseLargePages) &&
4832 FLAG_IS_DEFAULT(UseSHM) &&
4833 FLAG_IS_DEFAULT(UseHugeTLBFS)) {
4834 UseLargePages = false;
4835 } else {
4836 warning("UseNUMA is not fully compatible with SHM/HugeTLBFS large pages, disabling adaptive resizing");
4837 UseAdaptiveSizePolicy = false;
4838 UseAdaptiveNUMAChunkSizing = false;
4839 }
4840 }
4841 }
4842 if (!UseNUMA && ForceNUMA) {
4843 UseNUMA = true;
4844 }
4845 }
4846
4847 if (MaxFDLimit) {
4848 // set the number of file descriptors to max. print out error
4849 // if getrlimit/setrlimit fails but continue regardless.
4850 struct rlimit nbr_files;
4851 int status = getrlimit(RLIMIT_NOFILE, &nbr_files);
4852 if (status != 0) {
4853 if (PrintMiscellaneous && (Verbose || WizardMode))
4854 perror("os::init_2 getrlimit failed");
4855 } else {
4856 nbr_files.rlim_cur = nbr_files.rlim_max;
4857 status = setrlimit(RLIMIT_NOFILE, &nbr_files);
4858 if (status != 0) {
4859 if (PrintMiscellaneous && (Verbose || WizardMode))
4860 perror("os::init_2 setrlimit failed");
4861 }
4862 }
4863 }
4864
4865 // Initialize lock used to serialize thread creation (see os::create_thread)
4866 Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false));
4867
4868 // at-exit methods are called in the reverse order of their registration.
4869 // atexit functions are called on return from main or as a result of a
4870 // call to exit(3C). There can be only 32 of these functions registered
4871 // and atexit() does not set errno.
4872
4873 if (PerfAllowAtExitRegistration) {
4874 // only register atexit functions if PerfAllowAtExitRegistration is set.
4875 // atexit functions can be delayed until process exit time, which
4876 // can be problematic for embedded VM situations. Embedded VMs should
4877 // call DestroyJavaVM() to assure that VM resources are released.
4878
4879 // note: perfMemory_exit_helper atexit function may be removed in
4880 // the future if the appropriate cleanup code can be added to the
4881 // VM_Exit VMOperation's doit method.
4882 if (atexit(perfMemory_exit_helper) != 0) {
4883 warning("os::init_2 atexit(perfMemory_exit_helper) failed");
4884 }
4885 }
4886
4887 // initialize thread priority policy
4888 prio_init();
4889
4890 return JNI_OK;
4891 }
4892
4893 // Mark the polling page as unreadable
4894 void os::make_polling_page_unreadable(void) {
4895 if( !guard_memory((char*)_polling_page, Linux::page_size()) )
4896 fatal("Could not disable polling page");
4897 };
4898
4899 // Mark the polling page as readable
4900 void os::make_polling_page_readable(void) {
4901 if( !linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) {
4902 fatal("Could not enable polling page");
4903 }
4904 };
4905
4906 int os::active_processor_count() {
4907 // Linux doesn't yet have a (official) notion of processor sets,
4908 // so just return the number of online processors.
4909 int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN);
4910 assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check");
4911 return online_cpus;
4912 }
4913
4914 void os::set_native_thread_name(const char *name) {
4915 // Not yet implemented.
4916 return;
4917 }
4918
4919 bool os::distribute_processes(uint length, uint* distribution) {
4920 // Not yet implemented.
4921 return false;
4922 }
4923
4924 bool os::bind_to_processor(uint processor_id) {
4925 // Not yet implemented.
4926 return false;
4927 }
4928
4929 ///
4930
4931 void os::SuspendedThreadTask::internal_do_task() {
4932 if (do_suspend(_thread->osthread())) {
4933 SuspendedThreadTaskContext context(_thread, _thread->osthread()->ucontext());
4934 do_task(context);
4935 do_resume(_thread->osthread());
4936 }
4937 }
4938
4939 class PcFetcher : public os::SuspendedThreadTask {
4940 public:
4941 PcFetcher(Thread* thread) : os::SuspendedThreadTask(thread) {}
4942 ExtendedPC result();
4943 protected:
4944 void do_task(const os::SuspendedThreadTaskContext& context);
4945 private:
4946 ExtendedPC _epc;
4947 };
4948
4949 ExtendedPC PcFetcher::result() {
4950 guarantee(is_done(), "task is not done yet.");
4951 return _epc;
4952 }
4953
4954 void PcFetcher::do_task(const os::SuspendedThreadTaskContext& context) {
4955 Thread* thread = context.thread();
4956 OSThread* osthread = thread->osthread();
4957 if (osthread->ucontext() != NULL) {
4958 _epc = os::Linux::ucontext_get_pc((ucontext_t *) context.ucontext());
4959 } else {
4960 // NULL context is unexpected, double-check this is the VMThread
4961 guarantee(thread->is_VM_thread(), "can only be called for VMThread");
4962 }
4963 }
4964
4965 // Suspends the target using the signal mechanism and then grabs the PC before
4966 // resuming the target. Used by the flat-profiler only
4967 ExtendedPC os::get_thread_pc(Thread* thread) {
4968 // Make sure that it is called by the watcher for the VMThread
4969 assert(Thread::current()->is_Watcher_thread(), "Must be watcher");
4970 assert(thread->is_VM_thread(), "Can only be called for VMThread");
4971
4972 PcFetcher fetcher(thread);
4973 fetcher.run();
4974 return fetcher.result();
4975 }
4976
4977 int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond, pthread_mutex_t *_mutex, const struct timespec *_abstime)
4978 {
4979 if (is_NPTL()) {
4980 return pthread_cond_timedwait(_cond, _mutex, _abstime);
4981 } else {
4982 // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control
4983 // word back to default 64bit precision if condvar is signaled. Java
4984 // wants 53bit precision. Save and restore current value.
4985 int fpu = get_fpu_control_word();
4986 int status = pthread_cond_timedwait(_cond, _mutex, _abstime);
4987 set_fpu_control_word(fpu);
4988 return status;
4989 }
4990 }
4991
4992 ////////////////////////////////////////////////////////////////////////////////
4993 // debug support
4994
4995 bool os::find(address addr, outputStream* st) {
4996 Dl_info dlinfo;
4997 memset(&dlinfo, 0, sizeof(dlinfo));
4998 if (dladdr(addr, &dlinfo) != 0) {
4999 st->print(PTR_FORMAT ": ", addr);
5000 if (dlinfo.dli_sname != NULL && dlinfo.dli_saddr != NULL) {
5001 st->print("%s+%#x", dlinfo.dli_sname,
5002 addr - (intptr_t)dlinfo.dli_saddr);
5003 } else if (dlinfo.dli_fbase != NULL) {
5004 st->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase);
5005 } else {
5006 st->print("<absolute address>");
5007 }
5008 if (dlinfo.dli_fname != NULL) {
5009 st->print(" in %s", dlinfo.dli_fname);
5010 }
5011 if (dlinfo.dli_fbase != NULL) {
5012 st->print(" at " PTR_FORMAT, dlinfo.dli_fbase);
5013 }
5014 st->cr();
5015
5016 if (Verbose) {
5017 // decode some bytes around the PC
5018 address begin = clamp_address_in_page(addr-40, addr, os::vm_page_size());
5019 address end = clamp_address_in_page(addr+40, addr, os::vm_page_size());
5020 address lowest = (address) dlinfo.dli_sname;
5021 if (!lowest) lowest = (address) dlinfo.dli_fbase;
5022 if (begin < lowest) begin = lowest;
5023 Dl_info dlinfo2;
5024 if (dladdr(end, &dlinfo2) != 0 && dlinfo2.dli_saddr != dlinfo.dli_saddr
5025 && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin)
5026 end = (address) dlinfo2.dli_saddr;
5027 Disassembler::decode(begin, end, st);
5028 }
5029 return true;
5030 }
5031 return false;
5032 }
5033
5034 ////////////////////////////////////////////////////////////////////////////////
5035 // misc
5036
5037 // This does not do anything on Linux. This is basically a hook for being
5038 // able to use structured exception handling (thread-local exception filters)
5039 // on, e.g., Win32.
5040 void
5041 os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method,
5042 JavaCallArguments* args, Thread* thread) {
5043 f(value, method, args, thread);
5044 }
5045
5046 void os::print_statistics() {
5047 }
5048
5049 int os::message_box(const char* title, const char* message) {
5050 int i;
5051 fdStream err(defaultStream::error_fd());
5052 for (i = 0; i < 78; i++) err.print_raw("=");
5053 err.cr();
5054 err.print_raw_cr(title);
5055 for (i = 0; i < 78; i++) err.print_raw("-");
5056 err.cr();
5057 err.print_raw_cr(message);
5058 for (i = 0; i < 78; i++) err.print_raw("=");
5059 err.cr();
5060
5061 char buf[16];
5062 // Prevent process from exiting upon "read error" without consuming all CPU
5063 while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); }
5064
5065 return buf[0] == 'y' || buf[0] == 'Y';
5066 }
5067
5068 int os::stat(const char *path, struct stat *sbuf) {
5069 char pathbuf[MAX_PATH];
5070 if (strlen(path) > MAX_PATH - 1) {
5071 errno = ENAMETOOLONG;
5072 return -1;
5073 }
5074 os::native_path(strcpy(pathbuf, path));
5075 return ::stat(pathbuf, sbuf);
5076 }
5077
5078 bool os::check_heap(bool force) {
5079 return true;
5080 }
5081
5082 int local_vsnprintf(char* buf, size_t count, const char* format, va_list args) {
5083 return ::vsnprintf(buf, count, format, args);
5084 }
5085
5086 // Is a (classpath) directory empty?
5087 bool os::dir_is_empty(const char* path) {
5088 DIR *dir = NULL;
5089 struct dirent *ptr;
5090
5091 dir = opendir(path);
5092 if (dir == NULL) return true;
5093
5094 /* Scan the directory */
5095 bool result = true;
5096 char buf[sizeof(struct dirent) + MAX_PATH];
5097 while (result && (ptr = ::readdir(dir)) != NULL) {
5098 if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) {
5099 result = false;
5100 }
5101 }
5102 closedir(dir);
5103 return result;
5104 }
5105
5106 // This code originates from JDK's sysOpen and open64_w
5107 // from src/solaris/hpi/src/system_md.c
5108
5109 #ifndef O_DELETE
5110 #define O_DELETE 0x10000
5111 #endif
5112
5113 // Open a file. Unlink the file immediately after open returns
5114 // if the specified oflag has the O_DELETE flag set.
5115 // O_DELETE is used only in j2se/src/share/native/java/util/zip/ZipFile.c
5116
5117 int os::open(const char *path, int oflag, int mode) {
5118
5119 if (strlen(path) > MAX_PATH - 1) {
5120 errno = ENAMETOOLONG;
5121 return -1;
5122 }
5123 int fd;
5124 int o_delete = (oflag & O_DELETE);
5125 oflag = oflag & ~O_DELETE;
5126
5127 fd = ::open64(path, oflag, mode);
5128 if (fd == -1) return -1;
5129
5130 //If the open succeeded, the file might still be a directory
5131 {
5132 struct stat64 buf64;
5133 int ret = ::fstat64(fd, &buf64);
5134 int st_mode = buf64.st_mode;
5135
5136 if (ret != -1) {
5137 if ((st_mode & S_IFMT) == S_IFDIR) {
5138 errno = EISDIR;
5139 ::close(fd);
5140 return -1;
5141 }
5142 } else {
5143 ::close(fd);
5144 return -1;
5145 }
5146 }
5147
5148 /*
5149 * All file descriptors that are opened in the JVM and not
5150 * specifically destined for a subprocess should have the
5151 * close-on-exec flag set. If we don't set it, then careless 3rd
5152 * party native code might fork and exec without closing all
5153 * appropriate file descriptors (e.g. as we do in closeDescriptors in
5154 * UNIXProcess.c), and this in turn might:
5155 *
5156 * - cause end-of-file to fail to be detected on some file
5157 * descriptors, resulting in mysterious hangs, or
5158 *
5159 * - might cause an fopen in the subprocess to fail on a system
5160 * suffering from bug 1085341.
5161 *
5162 * (Yes, the default setting of the close-on-exec flag is a Unix
5163 * design flaw)
5164 *
5165 * See:
5166 * 1085341: 32-bit stdio routines should support file descriptors >255
5167 * 4843136: (process) pipe file descriptor from Runtime.exec not being closed
5168 * 6339493: (process) Runtime.exec does not close all file descriptors on Solaris 9
5169 */
5170 #ifdef FD_CLOEXEC
5171 {
5172 int flags = ::fcntl(fd, F_GETFD);
5173 if (flags != -1)
5174 ::fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
5175 }
5176 #endif
5177
5178 if (o_delete != 0) {
5179 ::unlink(path);
5180 }
5181 return fd;
5182 }
5183
5184
5185 // create binary file, rewriting existing file if required
5186 int os::create_binary_file(const char* path, bool rewrite_existing) {
5187 int oflags = O_WRONLY | O_CREAT;
5188 if (!rewrite_existing) {
5189 oflags |= O_EXCL;
5190 }
5191 return ::open64(path, oflags, S_IREAD | S_IWRITE);
5192 }
5193
5194 // return current position of file pointer
5195 jlong os::current_file_offset(int fd) {
5196 return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR);
5197 }
5198
5199 // move file pointer to the specified offset
5200 jlong os::seek_to_file_offset(int fd, jlong offset) {
5201 return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET);
5202 }
5203
5204 // This code originates from JDK's sysAvailable
5205 // from src/solaris/hpi/src/native_threads/src/sys_api_td.c
5206
5207 int os::available(int fd, jlong *bytes) {
5208 jlong cur, end;
5209 int mode;
5210 struct stat64 buf64;
5211
5212 if (::fstat64(fd, &buf64) >= 0) {
5213 mode = buf64.st_mode;
5214 if (S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) {
5215 /*
5216 * XXX: is the following call interruptible? If so, this might
5217 * need to go through the INTERRUPT_IO() wrapper as for other
5218 * blocking, interruptible calls in this file.
5219 */
5220 int n;
5221 if (::ioctl(fd, FIONREAD, &n) >= 0) {
5222 *bytes = n;
5223 return 1;
5224 }
5225 }
5226 }
5227 if ((cur = ::lseek64(fd, 0L, SEEK_CUR)) == -1) {
5228 return 0;
5229 } else if ((end = ::lseek64(fd, 0L, SEEK_END)) == -1) {
5230 return 0;
5231 } else if (::lseek64(fd, cur, SEEK_SET) == -1) {
5232 return 0;
5233 }
5234 *bytes = end - cur;
5235 return 1;
5236 }
5237
5238 int os::socket_available(int fd, jint *pbytes) {
5239 // Linux doc says EINTR not returned, unlike Solaris
5240 int ret = ::ioctl(fd, FIONREAD, pbytes);
5241
5242 //%% note ioctl can return 0 when successful, JVM_SocketAvailable
5243 // is expected to return 0 on failure and 1 on success to the jdk.
5244 return (ret < 0) ? 0 : 1;
5245 }
5246
5247 // Map a block of memory.
5248 char* os::pd_map_memory(int fd, const char* file_name, size_t file_offset,
5249 char *addr, size_t bytes, bool read_only,
5250 bool allow_exec) {
5251 int prot;
5252 int flags = MAP_PRIVATE;
5253
5254 if (read_only) {
5255 prot = PROT_READ;
5256 } else {
5257 prot = PROT_READ | PROT_WRITE;
5258 }
5259
5260 if (allow_exec) {
5261 prot |= PROT_EXEC;
5262 }
5263
5264 if (addr != NULL) {
5265 flags |= MAP_FIXED;
5266 }
5267
5268 char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags,
5269 fd, file_offset);
5270 if (mapped_address == MAP_FAILED) {
5271 return NULL;
5272 }
5273 return mapped_address;
5274 }
5275
5276
5277 // Remap a block of memory.
5278 char* os::pd_remap_memory(int fd, const char* file_name, size_t file_offset,
5279 char *addr, size_t bytes, bool read_only,
5280 bool allow_exec) {
5281 // same as map_memory() on this OS
5282 return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only,
5283 allow_exec);
5284 }
5285
5286
5287 // Unmap a block of memory.
5288 bool os::pd_unmap_memory(char* addr, size_t bytes) {
5289 return munmap(addr, bytes) == 0;
5290 }
5291
5292 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time);
5293
5294 static clockid_t thread_cpu_clockid(Thread* thread) {
5295 pthread_t tid = thread->osthread()->pthread_id();
5296 clockid_t clockid;
5297
5298 // Get thread clockid
5299 int rc = os::Linux::pthread_getcpuclockid(tid, &clockid);
5300 assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code");
5301 return clockid;
5302 }
5303
5304 // current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool)
5305 // are used by JVM M&M and JVMTI to get user+sys or user CPU time
5306 // of a thread.
5307 //
5308 // current_thread_cpu_time() and thread_cpu_time(Thread*) returns
5309 // the fast estimate available on the platform.
5310
5311 jlong os::current_thread_cpu_time() {
5312 if (os::Linux::supports_fast_thread_cpu_time()) {
5313 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
5314 } else {
5315 // return user + sys since the cost is the same
5316 return slow_thread_cpu_time(Thread::current(), true /* user + sys */);
5317 }
5318 }
5319
5320 jlong os::thread_cpu_time(Thread* thread) {
5321 // consistent with what current_thread_cpu_time() returns
5322 if (os::Linux::supports_fast_thread_cpu_time()) {
5323 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread));
5324 } else {
5325 return slow_thread_cpu_time(thread, true /* user + sys */);
5326 }
5327 }
5328
5329 jlong os::current_thread_cpu_time(bool user_sys_cpu_time) {
5330 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
5331 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
5332 } else {
5333 return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time);
5334 }
5335 }
5336
5337 jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
5338 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
5339 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread));
5340 } else {
5341 return slow_thread_cpu_time(thread, user_sys_cpu_time);
5342 }
5343 }
5344
5345 //
5346 // -1 on error.
5347 //
5348
5349 PRAGMA_DIAG_PUSH
5350 PRAGMA_FORMAT_NONLITERAL_IGNORED
5351 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
5352 static bool proc_task_unchecked = true;
5353 static const char *proc_stat_path = "/proc/%d/stat";
5354 pid_t tid = thread->osthread()->thread_id();
5355 char *s;
5356 char stat[2048];
5357 int statlen;
5358 char proc_name[64];
5359 int count;
5360 long sys_time, user_time;
5361 char cdummy;
5362 int idummy;
5363 long ldummy;
5364 FILE *fp;
5365
5366 // The /proc/<tid>/stat aggregates per-process usage on
5367 // new Linux kernels 2.6+ where NPTL is supported.
5368 // The /proc/self/task/<tid>/stat still has the per-thread usage.
5369 // See bug 6328462.
5370 // There possibly can be cases where there is no directory
5371 // /proc/self/task, so we check its availability.
5372 if (proc_task_unchecked && os::Linux::is_NPTL()) {
5373 // This is executed only once
5374 proc_task_unchecked = false;
5375 fp = fopen("/proc/self/task", "r");
5376 if (fp != NULL) {
5377 proc_stat_path = "/proc/self/task/%d/stat";
5378 fclose(fp);
5379 }
5380 }
5381
5382 sprintf(proc_name, proc_stat_path, tid);
5383 fp = fopen(proc_name, "r");
5384 if ( fp == NULL ) return -1;
5385 statlen = fread(stat, 1, 2047, fp);
5386 stat[statlen] = '\0';
5387 fclose(fp);
5388
5389 // Skip pid and the command string. Note that we could be dealing with
5390 // weird command names, e.g. user could decide to rename java launcher
5391 // to "java 1.4.2 :)", then the stat file would look like
5392 // 1234 (java 1.4.2 :)) R ... ...
5393 // We don't really need to know the command string, just find the last
5394 // occurrence of ")" and then start parsing from there. See bug 4726580.
5395 s = strrchr(stat, ')');
5396 if (s == NULL ) return -1;
5397
5398 // Skip blank chars
5399 do s++; while (isspace(*s));
5400
5401 count = sscanf(s,"%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu",
5402 &cdummy, &idummy, &idummy, &idummy, &idummy, &idummy,
5403 &ldummy, &ldummy, &ldummy, &ldummy, &ldummy,
5404 &user_time, &sys_time);
5405 if ( count != 13 ) return -1;
5406 if (user_sys_cpu_time) {
5407 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec);
5408 } else {
5409 return (jlong)user_time * (1000000000 / clock_tics_per_sec);
5410 }
5411 }
5412 PRAGMA_DIAG_POP
5413
5414 void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
5415 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits
5416 info_ptr->may_skip_backward = false; // elapsed time not wall time
5417 info_ptr->may_skip_forward = false; // elapsed time not wall time
5418 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned
5419 }
5420
5421 void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
5422 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits
5423 info_ptr->may_skip_backward = false; // elapsed time not wall time
5424 info_ptr->may_skip_forward = false; // elapsed time not wall time
5425 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned
5426 }
5427
5428 bool os::is_thread_cpu_time_supported() {
5429 return true;
5430 }
5431
5432 // System loadavg support. Returns -1 if load average cannot be obtained.
5433 // Linux doesn't yet have a (official) notion of processor sets,
5434 // so just return the system wide load average.
5435 int os::loadavg(double loadavg[], int nelem) {
5436 return ::getloadavg(loadavg, nelem);
5437 }
5438
5439 void os::pause() {
5440 char filename[MAX_PATH];
5441 if (PauseAtStartupFile && PauseAtStartupFile[0]) {
5442 jio_snprintf(filename, MAX_PATH, PauseAtStartupFile);
5443 } else {
5444 jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id());
5445 }
5446
5447 int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
5448 if (fd != -1) {
5449 struct stat buf;
5450 ::close(fd);
5451 while (::stat(filename, &buf) == 0) {
5452 (void)::poll(NULL, 0, 100);
5453 }
5454 } else {
5455 jio_fprintf(stderr,
5456 "Could not open pause file '%s', continuing immediately.\n", filename);
5457 }
5458 }
5459
5460
5461 // Refer to the comments in os_solaris.cpp park-unpark.
5462 //
5463 // Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can
5464 // hang indefinitely. For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable.
5465 // For specifics regarding the bug see GLIBC BUGID 261237 :
5466 // http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html.
5467 // Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future
5468 // will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar
5469 // is used. (The simple C test-case provided in the GLIBC bug report manifests the
5470 // hang). The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos()
5471 // and monitorenter when we're using 1-0 locking. All those operations may result in
5472 // calls to pthread_cond_timedwait(). Using LD_ASSUME_KERNEL to use an older version
5473 // of libpthread avoids the problem, but isn't practical.
5474 //
5475 // Possible remedies:
5476 //
5477 // 1. Establish a minimum relative wait time. 50 to 100 msecs seems to work.
5478 // This is palliative and probabilistic, however. If the thread is preempted
5479 // between the call to compute_abstime() and pthread_cond_timedwait(), more
5480 // than the minimum period may have passed, and the abstime may be stale (in the
5481 // past) resultin in a hang. Using this technique reduces the odds of a hang
5482 // but the JVM is still vulnerable, particularly on heavily loaded systems.
5483 //
5484 // 2. Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead
5485 // of the usual flag-condvar-mutex idiom. The write side of the pipe is set
5486 // NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo)
5487 // reduces to poll()+read(). This works well, but consumes 2 FDs per extant
5488 // thread.
5489 //
5490 // 3. Embargo pthread_cond_timedwait() and implement a native "chron" thread
5491 // that manages timeouts. We'd emulate pthread_cond_timedwait() by enqueuing
5492 // a timeout request to the chron thread and then blocking via pthread_cond_wait().
5493 // This also works well. In fact it avoids kernel-level scalability impediments
5494 // on certain platforms that don't handle lots of active pthread_cond_timedwait()
5495 // timers in a graceful fashion.
5496 //
5497 // 4. When the abstime value is in the past it appears that control returns
5498 // correctly from pthread_cond_timedwait(), but the condvar is left corrupt.
5499 // Subsequent timedwait/wait calls may hang indefinitely. Given that, we
5500 // can avoid the problem by reinitializing the condvar -- by cond_destroy()
5501 // followed by cond_init() -- after all calls to pthread_cond_timedwait().
5502 // It may be possible to avoid reinitialization by checking the return
5503 // value from pthread_cond_timedwait(). In addition to reinitializing the
5504 // condvar we must establish the invariant that cond_signal() is only called
5505 // within critical sections protected by the adjunct mutex. This prevents
5506 // cond_signal() from "seeing" a condvar that's in the midst of being
5507 // reinitialized or that is corrupt. Sadly, this invariant obviates the
5508 // desirable signal-after-unlock optimization that avoids futile context switching.
5509 //
5510 // I'm also concerned that some versions of NTPL might allocate an auxilliary
5511 // structure when a condvar is used or initialized. cond_destroy() would
5512 // release the helper structure. Our reinitialize-after-timedwait fix
5513 // put excessive stress on malloc/free and locks protecting the c-heap.
5514 //
5515 // We currently use (4). See the WorkAroundNTPLTimedWaitHang flag.
5516 // It may be possible to refine (4) by checking the kernel and NTPL verisons
5517 // and only enabling the work-around for vulnerable environments.
5518
5519 // utility to compute the abstime argument to timedwait:
5520 // millis is the relative timeout time
5521 // abstime will be the absolute timeout time
5522 // TODO: replace compute_abstime() with unpackTime()
5523
5524 static struct timespec* compute_abstime(timespec* abstime, jlong millis) {
5525 if (millis < 0) millis = 0;
5526
5527 jlong seconds = millis / 1000;
5528 millis %= 1000;
5529 if (seconds > 50000000) { // see man cond_timedwait(3T)
5530 seconds = 50000000;
5531 }
5532
5533 if (os::Linux::supports_monotonic_clock()) {
5534 struct timespec now;
5535 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now);
5536 assert_status(status == 0, status, "clock_gettime");
5537 abstime->tv_sec = now.tv_sec + seconds;
5538 long nanos = now.tv_nsec + millis * NANOSECS_PER_MILLISEC;
5539 if (nanos >= NANOSECS_PER_SEC) {
5540 abstime->tv_sec += 1;
5541 nanos -= NANOSECS_PER_SEC;
5542 }
5543 abstime->tv_nsec = nanos;
5544 } else {
5545 struct timeval now;
5546 int status = gettimeofday(&now, NULL);
5547 assert(status == 0, "gettimeofday");
5548 abstime->tv_sec = now.tv_sec + seconds;
5549 long usec = now.tv_usec + millis * 1000;
5550 if (usec >= 1000000) {
5551 abstime->tv_sec += 1;
5552 usec -= 1000000;
5553 }
5554 abstime->tv_nsec = usec * 1000;
5555 }
5556 return abstime;
5557 }
5558
5559
5560 // Test-and-clear _Event, always leaves _Event set to 0, returns immediately.
5561 // Conceptually TryPark() should be equivalent to park(0).
5562
5563 int os::PlatformEvent::TryPark() {
5564 for (;;) {
5565 const int v = _Event ;
5566 guarantee ((v == 0) || (v == 1), "invariant") ;
5567 if (Atomic::cmpxchg (0, &_Event, v) == v) return v ;
5568 }
5569 }
5570
5571 void os::PlatformEvent::park() { // AKA "down()"
5572 // Invariant: Only the thread associated with the Event/PlatformEvent
5573 // may call park().
5574 // TODO: assert that _Assoc != NULL or _Assoc == Self
5575 int v ;
5576 for (;;) {
5577 v = _Event ;
5578 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ;
5579 }
5580 guarantee (v >= 0, "invariant") ;
5581 if (v == 0) {
5582 // Do this the hard way by blocking ...
5583 int status = pthread_mutex_lock(_mutex);
5584 assert_status(status == 0, status, "mutex_lock");
5585 guarantee (_nParked == 0, "invariant") ;
5586 ++ _nParked ;
5587 while (_Event < 0) {
5588 status = pthread_cond_wait(_cond, _mutex);
5589 // for some reason, under 2.7 lwp_cond_wait() may return ETIME ...
5590 // Treat this the same as if the wait was interrupted
5591 if (status == ETIME) { status = EINTR; }
5592 assert_status(status == 0 || status == EINTR, status, "cond_wait");
5593 }
5594 -- _nParked ;
5595
5596 _Event = 0 ;
5597 status = pthread_mutex_unlock(_mutex);
5598 assert_status(status == 0, status, "mutex_unlock");
5599 // Paranoia to ensure our locked and lock-free paths interact
5600 // correctly with each other.
5601 OrderAccess::fence();
5602 }
5603 guarantee (_Event >= 0, "invariant") ;
5604 }
5605
5606 int os::PlatformEvent::park(jlong millis) {
5607 guarantee (_nParked == 0, "invariant") ;
5608
5609 int v ;
5610 for (;;) {
5611 v = _Event ;
5612 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ;
5613 }
5614 guarantee (v >= 0, "invariant") ;
5615 if (v != 0) return OS_OK ;
5616
5617 // We do this the hard way, by blocking the thread.
5618 // Consider enforcing a minimum timeout value.
5619 struct timespec abst;
5620 compute_abstime(&abst, millis);
5621
5622 int ret = OS_TIMEOUT;
5623 int status = pthread_mutex_lock(_mutex);
5624 assert_status(status == 0, status, "mutex_lock");
5625 guarantee (_nParked == 0, "invariant") ;
5626 ++_nParked ;
5627
5628 // Object.wait(timo) will return because of
5629 // (a) notification
5630 // (b) timeout
5631 // (c) thread.interrupt
5632 //
5633 // Thread.interrupt and object.notify{All} both call Event::set.
5634 // That is, we treat thread.interrupt as a special case of notification.
5635 // The underlying Solaris implementation, cond_timedwait, admits
5636 // spurious/premature wakeups, but the JLS/JVM spec prevents the
5637 // JVM from making those visible to Java code. As such, we must
5638 // filter out spurious wakeups. We assume all ETIME returns are valid.
5639 //
5640 // TODO: properly differentiate simultaneous notify+interrupt.
5641 // In that case, we should propagate the notify to another waiter.
5642
5643 while (_Event < 0) {
5644 status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst);
5645 if (status != 0 && WorkAroundNPTLTimedWaitHang) {
5646 pthread_cond_destroy (_cond);
5647 pthread_cond_init (_cond, os::Linux::condAttr()) ;
5648 }
5649 assert_status(status == 0 || status == EINTR ||
5650 status == ETIME || status == ETIMEDOUT,
5651 status, "cond_timedwait");
5652 if (!FilterSpuriousWakeups) break ; // previous semantics
5653 if (status == ETIME || status == ETIMEDOUT) break ;
5654 // We consume and ignore EINTR and spurious wakeups.
5655 }
5656 --_nParked ;
5657 if (_Event >= 0) {
5658 ret = OS_OK;
5659 }
5660 _Event = 0 ;
5661 status = pthread_mutex_unlock(_mutex);
5662 assert_status(status == 0, status, "mutex_unlock");
5663 assert (_nParked == 0, "invariant") ;
5664 // Paranoia to ensure our locked and lock-free paths interact
5665 // correctly with each other.
5666 OrderAccess::fence();
5667 return ret;
5668 }
5669
5670 void os::PlatformEvent::unpark() {
5671 // Transitions for _Event:
5672 // 0 :=> 1
5673 // 1 :=> 1
5674 // -1 :=> either 0 or 1; must signal target thread
5675 // That is, we can safely transition _Event from -1 to either
5676 // 0 or 1. Forcing 1 is slightly more efficient for back-to-back
5677 // unpark() calls.
5678 // See also: "Semaphores in Plan 9" by Mullender & Cox
5679 //
5680 // Note: Forcing a transition from "-1" to "1" on an unpark() means
5681 // that it will take two back-to-back park() calls for the owning
5682 // thread to block. This has the benefit of forcing a spurious return
5683 // from the first park() call after an unpark() call which will help
5684 // shake out uses of park() and unpark() without condition variables.
5685
5686 if (Atomic::xchg(1, &_Event) >= 0) return;
5687
5688 // Wait for the thread associated with the event to vacate
5689 int status = pthread_mutex_lock(_mutex);
5690 assert_status(status == 0, status, "mutex_lock");
5691 int AnyWaiters = _nParked;
5692 assert(AnyWaiters == 0 || AnyWaiters == 1, "invariant");
5693 if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) {
5694 AnyWaiters = 0;
5695 pthread_cond_signal(_cond);
5696 }
5697 status = pthread_mutex_unlock(_mutex);
5698 assert_status(status == 0, status, "mutex_unlock");
5699 if (AnyWaiters != 0) {
5700 status = pthread_cond_signal(_cond);
5701 assert_status(status == 0, status, "cond_signal");
5702 }
5703
5704 // Note that we signal() _after dropping the lock for "immortal" Events.
5705 // This is safe and avoids a common class of futile wakeups. In rare
5706 // circumstances this can cause a thread to return prematurely from
5707 // cond_{timed}wait() but the spurious wakeup is benign and the victim will
5708 // simply re-test the condition and re-park itself.
5709 }
5710
5711
5712 // JSR166
5713 // -------------------------------------------------------
5714
5715 /*
5716 * The solaris and linux implementations of park/unpark are fairly
5717 * conservative for now, but can be improved. They currently use a
5718 * mutex/condvar pair, plus a a count.
5719 * Park decrements count if > 0, else does a condvar wait. Unpark
5720 * sets count to 1 and signals condvar. Only one thread ever waits
5721 * on the condvar. Contention seen when trying to park implies that someone
5722 * is unparking you, so don't wait. And spurious returns are fine, so there
5723 * is no need to track notifications.
5724 */
5725
5726 /*
5727 * This code is common to linux and solaris and will be moved to a
5728 * common place in dolphin.
5729 *
5730 * The passed in time value is either a relative time in nanoseconds
5731 * or an absolute time in milliseconds. Either way it has to be unpacked
5732 * into suitable seconds and nanoseconds components and stored in the
5733 * given timespec structure.
5734 * Given time is a 64-bit value and the time_t used in the timespec is only
5735 * a signed-32-bit value (except on 64-bit Linux) we have to watch for
5736 * overflow if times way in the future are given. Further on Solaris versions
5737 * prior to 10 there is a restriction (see cond_timedwait) that the specified
5738 * number of seconds, in abstime, is less than current_time + 100,000,000.
5739 * As it will be 28 years before "now + 100000000" will overflow we can
5740 * ignore overflow and just impose a hard-limit on seconds using the value
5741 * of "now + 100,000,000". This places a limit on the timeout of about 3.17
5742 * years from "now".
5743 */
5744
5745 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) {
5746 assert (time > 0, "convertTime");
5747 time_t max_secs = 0;
5748
5749 if (!os::Linux::supports_monotonic_clock() || isAbsolute) {
5750 struct timeval now;
5751 int status = gettimeofday(&now, NULL);
5752 assert(status == 0, "gettimeofday");
5753
5754 max_secs = now.tv_sec + MAX_SECS;
5755
5756 if (isAbsolute) {
5757 jlong secs = time / 1000;
5758 if (secs > max_secs) {
5759 absTime->tv_sec = max_secs;
5760 } else {
5761 absTime->tv_sec = secs;
5762 }
5763 absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC;
5764 } else {
5765 jlong secs = time / NANOSECS_PER_SEC;
5766 if (secs >= MAX_SECS) {
5767 absTime->tv_sec = max_secs;
5768 absTime->tv_nsec = 0;
5769 } else {
5770 absTime->tv_sec = now.tv_sec + secs;
5771 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000;
5772 if (absTime->tv_nsec >= NANOSECS_PER_SEC) {
5773 absTime->tv_nsec -= NANOSECS_PER_SEC;
5774 ++absTime->tv_sec; // note: this must be <= max_secs
5775 }
5776 }
5777 }
5778 } else {
5779 // must be relative using monotonic clock
5780 struct timespec now;
5781 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now);
5782 assert_status(status == 0, status, "clock_gettime");
5783 max_secs = now.tv_sec + MAX_SECS;
5784 jlong secs = time / NANOSECS_PER_SEC;
5785 if (secs >= MAX_SECS) {
5786 absTime->tv_sec = max_secs;
5787 absTime->tv_nsec = 0;
5788 } else {
5789 absTime->tv_sec = now.tv_sec + secs;
5790 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_nsec;
5791 if (absTime->tv_nsec >= NANOSECS_PER_SEC) {
5792 absTime->tv_nsec -= NANOSECS_PER_SEC;
5793 ++absTime->tv_sec; // note: this must be <= max_secs
5794 }
5795 }
5796 }
5797 assert(absTime->tv_sec >= 0, "tv_sec < 0");
5798 assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs");
5799 assert(absTime->tv_nsec >= 0, "tv_nsec < 0");
5800 assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec");
5801 }
5802
5803 void Parker::park(bool isAbsolute, jlong time) {
5804 // Ideally we'd do something useful while spinning, such
5805 // as calling unpackTime().
5806
5807 // Optional fast-path check:
5808 // Return immediately if a permit is available.
5809 // We depend on Atomic::xchg() having full barrier semantics
5810 // since we are doing a lock-free update to _counter.
5811 if (Atomic::xchg(0, &_counter) > 0) return;
5812
5813 Thread* thread = Thread::current();
5814 assert(thread->is_Java_thread(), "Must be JavaThread");
5815 JavaThread *jt = (JavaThread *)thread;
5816
5817 // Optional optimization -- avoid state transitions if there's an interrupt pending.
5818 // Check interrupt before trying to wait
5819 if (Thread::is_interrupted(thread, false)) {
5820 return;
5821 }
5822
5823 // Next, demultiplex/decode time arguments
5824 timespec absTime;
5825 if (time < 0 || (isAbsolute && time == 0) ) { // don't wait at all
5826 return;
5827 }
5828 if (time > 0) {
5829 unpackTime(&absTime, isAbsolute, time);
5830 }
5831
5832
5833 // Enter safepoint region
5834 // Beware of deadlocks such as 6317397.
5835 // The per-thread Parker:: mutex is a classic leaf-lock.
5836 // In particular a thread must never block on the Threads_lock while
5837 // holding the Parker:: mutex. If safepoints are pending both the
5838 // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock.
5839 ThreadBlockInVM tbivm(jt);
5840
5841 // Don't wait if cannot get lock since interference arises from
5842 // unblocking. Also. check interrupt before trying wait
5843 if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) {
5844 return;
5845 }
5846
5847 int status ;
5848 if (_counter > 0) { // no wait needed
5849 _counter = 0;
5850 status = pthread_mutex_unlock(_mutex);
5851 assert (status == 0, "invariant") ;
5852 // Paranoia to ensure our locked and lock-free paths interact
5853 // correctly with each other and Java-level accesses.
5854 OrderAccess::fence();
5855 return;
5856 }
5857
5858 #ifdef ASSERT
5859 // Don't catch signals while blocked; let the running threads have the signals.
5860 // (This allows a debugger to break into the running thread.)
5861 sigset_t oldsigs;
5862 sigset_t* allowdebug_blocked = os::Linux::allowdebug_blocked_signals();
5863 pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs);
5864 #endif
5865
5866 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */);
5867 jt->set_suspend_equivalent();
5868 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
5869
5870 assert(_cur_index == -1, "invariant");
5871 if (time == 0) {
5872 _cur_index = REL_INDEX; // arbitrary choice when not timed
5873 status = pthread_cond_wait (&_cond[_cur_index], _mutex) ;
5874 } else {
5875 _cur_index = isAbsolute ? ABS_INDEX : REL_INDEX;
5876 status = os::Linux::safe_cond_timedwait (&_cond[_cur_index], _mutex, &absTime) ;
5877 if (status != 0 && WorkAroundNPTLTimedWaitHang) {
5878 pthread_cond_destroy (&_cond[_cur_index]) ;
5879 pthread_cond_init (&_cond[_cur_index], isAbsolute ? NULL : os::Linux::condAttr());
5880 }
5881 }
5882 _cur_index = -1;
5883 assert_status(status == 0 || status == EINTR ||
5884 status == ETIME || status == ETIMEDOUT,
5885 status, "cond_timedwait");
5886
5887 #ifdef ASSERT
5888 pthread_sigmask(SIG_SETMASK, &oldsigs, NULL);
5889 #endif
5890
5891 _counter = 0 ;
5892 status = pthread_mutex_unlock(_mutex) ;
5893 assert_status(status == 0, status, "invariant") ;
5894 // Paranoia to ensure our locked and lock-free paths interact
5895 // correctly with each other and Java-level accesses.
5896 OrderAccess::fence();
5897
5898 // If externally suspended while waiting, re-suspend
5899 if (jt->handle_special_suspend_equivalent_condition()) {
5900 jt->java_suspend_self();
5901 }
5902 }
5903
5904 void Parker::unpark() {
5905 int s, status ;
5906 status = pthread_mutex_lock(_mutex);
5907 assert (status == 0, "invariant") ;
5908 s = _counter;
5909 _counter = 1;
5910 if (s < 1) {
5911 // thread might be parked
5912 if (_cur_index != -1) {
5913 // thread is definitely parked
5914 if (WorkAroundNPTLTimedWaitHang) {
5915 status = pthread_cond_signal (&_cond[_cur_index]);
5916 assert (status == 0, "invariant");
5917 status = pthread_mutex_unlock(_mutex);
5918 assert (status == 0, "invariant");
5919 } else {
5920 status = pthread_mutex_unlock(_mutex);
5921 assert (status == 0, "invariant");
5922 status = pthread_cond_signal (&_cond[_cur_index]);
5923 assert (status == 0, "invariant");
5924 }
5925 } else {
5926 pthread_mutex_unlock(_mutex);
5927 assert (status == 0, "invariant") ;
5928 }
5929 } else {
5930 pthread_mutex_unlock(_mutex);
5931 assert (status == 0, "invariant") ;
5932 }
5933 }
5934
5935
5936 extern char** environ;
5937
5938 // Run the specified command in a separate process. Return its exit value,
5939 // or -1 on failure (e.g. can't fork a new process).
5940 // Unlike system(), this function can be called from signal handler. It
5941 // doesn't block SIGINT et al.
5942 int os::fork_and_exec(char* cmd) {
5943 const char * argv[4] = {"sh", "-c", cmd, NULL};
5944
5945 pid_t pid = fork();
5946
5947 if (pid < 0) {
5948 // fork failed
5949 return -1;
5950
5951 } else if (pid == 0) {
5952 // child process
5953
5954 execve("/bin/sh", (char* const*)argv, environ);
5955
5956 // execve failed
5957 _exit(-1);
5958
5959 } else {
5960 // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't
5961 // care about the actual exit code, for now.
5962
5963 int status;
5964
5965 // Wait for the child process to exit. This returns immediately if
5966 // the child has already exited. */
5967 while (waitpid(pid, &status, 0) < 0) {
5968 switch (errno) {
5969 case ECHILD: return 0;
5970 case EINTR: break;
5971 default: return -1;
5972 }
5973 }
5974
5975 if (WIFEXITED(status)) {
5976 // The child exited normally; get its exit code.
5977 return WEXITSTATUS(status);
5978 } else if (WIFSIGNALED(status)) {
5979 // The child exited because of a signal
5980 // The best value to return is 0x80 + signal number,
5981 // because that is what all Unix shells do, and because
5982 // it allows callers to distinguish between process exit and
5983 // process death by signal.
5984 return 0x80 + WTERMSIG(status);
5985 } else {
5986 // Unknown exit code; pass it through
5987 return status;
5988 }
5989 }
5990 }
5991
5992 // is_headless_jre()
5993 //
5994 // Test for the existence of xawt/libmawt.so or libawt_xawt.so
5995 // in order to report if we are running in a headless jre
5996 //
5997 // Since JDK8 xawt/libmawt.so was moved into the same directory
5998 // as libawt.so, and renamed libawt_xawt.so
5999 //
6000 bool os::is_headless_jre() {
6001 struct stat statbuf;
6002 char buf[MAXPATHLEN];
6003 char libmawtpath[MAXPATHLEN];
6004 const char *xawtstr = "/xawt/libmawt.so";
6005 const char *new_xawtstr = "/libawt_xawt.so";
6006 char *p;
6007
6008 // Get path to libjvm.so
6009 os::jvm_path(buf, sizeof(buf));
6010
6011 // Get rid of libjvm.so
6012 p = strrchr(buf, '/');
6013 if (p == NULL) return false;
6014 else *p = '\0';
6015
6016 // Get rid of client or server
6017 p = strrchr(buf, '/');
6018 if (p == NULL) return false;
6019 else *p = '\0';
6020
6021 // check xawt/libmawt.so
6022 strcpy(libmawtpath, buf);
6023 strcat(libmawtpath, xawtstr);
6024 if (::stat(libmawtpath, &statbuf) == 0) return false;
6025
6026 // check libawt_xawt.so
6027 strcpy(libmawtpath, buf);
6028 strcat(libmawtpath, new_xawtstr);
6029 if (::stat(libmawtpath, &statbuf) == 0) return false;
6030
6031 return true;
6032 }
6033
6034 // Get the default path to the core file
6035 // Returns the length of the string
6036 int os::get_core_path(char* buffer, size_t bufferSize) {
6037 const char* p = get_current_directory(buffer, bufferSize);
6038
6039 if (p == NULL) {
6040 assert(p != NULL, "failed to get current directory");
6041 return 0;
6042 }
6043
6044 return strlen(buffer);
6045 }
6046
6047 /////////////// Unit tests ///////////////
6048
6049 #ifndef PRODUCT
6050
6051 #define test_log(...) \
6052 do {\
6053 if (VerboseInternalVMTests) { \
6054 tty->print_cr(__VA_ARGS__); \
6055 tty->flush(); \
6056 }\
6057 } while (false)
6058
6059 class TestReserveMemorySpecial : AllStatic {
6060 public:
6061 static void small_page_write(void* addr, size_t size) {
6062 size_t page_size = os::vm_page_size();
6063
6064 char* end = (char*)addr + size;
6065 for (char* p = (char*)addr; p < end; p += page_size) {
6066 *p = 1;
6067 }
6068 }
6069
6070 static void test_reserve_memory_special_huge_tlbfs_only(size_t size) {
6071 if (!UseHugeTLBFS) {
6072 return;
6073 }
6074
6075 test_log("test_reserve_memory_special_huge_tlbfs_only(" SIZE_FORMAT ")", size);
6076
6077 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_only(size, NULL, false);
6078
6079 if (addr != NULL) {
6080 small_page_write(addr, size);
6081
6082 os::Linux::release_memory_special_huge_tlbfs(addr, size);
6083 }
6084 }
6085
6086 static void test_reserve_memory_special_huge_tlbfs_only() {
6087 if (!UseHugeTLBFS) {
6088 return;
6089 }
6090
6091 size_t lp = os::large_page_size();
6092
6093 for (size_t size = lp; size <= lp * 10; size += lp) {
6094 test_reserve_memory_special_huge_tlbfs_only(size);
6095 }
6096 }
6097
6098 static void test_reserve_memory_special_huge_tlbfs_mixed(size_t size, size_t alignment) {
6099 if (!UseHugeTLBFS) {
6100 return;
6101 }
6102
6103 test_log("test_reserve_memory_special_huge_tlbfs_mixed(" SIZE_FORMAT ", " SIZE_FORMAT ")",
6104 size, alignment);
6105
6106 assert(size >= os::large_page_size(), "Incorrect input to test");
6107
6108 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, NULL, false);
6109
6110 if (addr != NULL) {
6111 small_page_write(addr, size);
6112
6113 os::Linux::release_memory_special_huge_tlbfs(addr, size);
6114 }
6115 }
6116
6117 static void test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(size_t size) {
6118 size_t lp = os::large_page_size();
6119 size_t ag = os::vm_allocation_granularity();
6120
6121 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) {
6122 test_reserve_memory_special_huge_tlbfs_mixed(size, alignment);
6123 }
6124 }
6125
6126 static void test_reserve_memory_special_huge_tlbfs_mixed() {
6127 size_t lp = os::large_page_size();
6128 size_t ag = os::vm_allocation_granularity();
6129
6130 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp);
6131 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + ag);
6132 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + lp / 2);
6133 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2);
6134 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 + ag);
6135 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 - ag);
6136 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 + lp / 2);
6137 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10);
6138 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10 + lp / 2);
6139 }
6140
6141 static void test_reserve_memory_special_huge_tlbfs() {
6142 if (!UseHugeTLBFS) {
6143 return;
6144 }
6145
6146 test_reserve_memory_special_huge_tlbfs_only();
6147 test_reserve_memory_special_huge_tlbfs_mixed();
6148 }
6149
6150 static void test_reserve_memory_special_shm(size_t size, size_t alignment) {
6151 if (!UseSHM) {
6152 return;
6153 }
6154
6155 test_log("test_reserve_memory_special_shm(" SIZE_FORMAT ", " SIZE_FORMAT ")", size, alignment);
6156
6157 char* addr = os::Linux::reserve_memory_special_shm(size, alignment, NULL, false);
6158
6159 if (addr != NULL) {
6160 assert(is_ptr_aligned(addr, alignment), "Check");
6161 assert(is_ptr_aligned(addr, os::large_page_size()), "Check");
6162
6163 small_page_write(addr, size);
6164
6165 os::Linux::release_memory_special_shm(addr, size);
6166 }
6167 }
6168
6169 static void test_reserve_memory_special_shm() {
6170 size_t lp = os::large_page_size();
6171 size_t ag = os::vm_allocation_granularity();
6172
6173 for (size_t size = ag; size < lp * 3; size += ag) {
6174 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) {
6175 test_reserve_memory_special_shm(size, alignment);
6176 }
6177 }
6178 }
6179
6180 static void test() {
6181 test_reserve_memory_special_huge_tlbfs();
6182 test_reserve_memory_special_shm();
6183 }
6184 };
6185
6186 void TestReserveMemorySpecial_test() {
6187 TestReserveMemorySpecial::test();
6188 }
6189
6190 #endif