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_linux.inline.hpp"
40 #include "os_share_linux.hpp"
41 #include "prims/jniFastGetField.hpp"
42 #include "prims/jvm.h"
43 #include "prims/jvm_misc.hpp"
44 #include "runtime/arguments.hpp"
45 #include "runtime/atomic.inline.hpp"
46 #include "runtime/extendedPC.hpp"
47 #include "runtime/globals.hpp"
48 #include "runtime/interfaceSupport.hpp"
49 #include "runtime/init.hpp"
50 #include "runtime/java.hpp"
51 #include "runtime/javaCalls.hpp"
52 #include "runtime/mutexLocker.hpp"
53 #include "runtime/objectMonitor.hpp"
54 #include "runtime/orderAccess.inline.hpp"
55 #include "runtime/osThread.hpp"
56 #include "runtime/perfMemory.hpp"
57 #include "runtime/sharedRuntime.hpp"
58 #include "runtime/statSampler.hpp"
59 #include "runtime/stubRoutines.hpp"
60 #include "runtime/thread.inline.hpp"
61 #include "runtime/threadCritical.hpp"
62 #include "runtime/timer.hpp"
63 #include "services/attachListener.hpp"
64 #include "services/memTracker.hpp"
65 #include "services/runtimeService.hpp"
66 #include "utilities/decoder.hpp"
67 #include "utilities/defaultStream.hpp"
68 #include "utilities/events.hpp"
69 #include "utilities/elfFile.hpp"
70 #include "utilities/growableArray.hpp"
71 #include "utilities/macros.hpp"
72 #include "utilities/vmError.hpp"
73
74 // put OS-includes here
75 # include <sys/types.h>
76 # include <sys/mman.h>
77 # include <sys/stat.h>
78 # include <sys/select.h>
79 # include <pthread.h>
80 # include <signal.h>
81 # include <errno.h>
82 # include <dlfcn.h>
83 # include <stdio.h>
84 # include <unistd.h>
85 # include <sys/resource.h>
86 # include <pthread.h>
87 # include <sys/stat.h>
88 # include <sys/time.h>
89 # include <sys/times.h>
90 # include <sys/utsname.h>
91 # include <sys/socket.h>
92 # include <sys/wait.h>
93 # include <pwd.h>
94 # include <poll.h>
95 # include <semaphore.h>
96 # include <fcntl.h>
97 # include <string.h>
98 # include <syscall.h>
99 # include <sys/sysinfo.h>
100 # include <gnu/libc-version.h>
101 # include <sys/ipc.h>
102 # include <sys/shm.h>
103 # include <link.h>
104 # include <stdint.h>
105 # include <inttypes.h>
106 # include <sys/ioctl.h>
107
108 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
109
110 // if RUSAGE_THREAD for getrusage() has not been defined, do it here. The code calling
111 // getrusage() is prepared to handle the associated failure.
112 #ifndef RUSAGE_THREAD
113 #define RUSAGE_THREAD (1) /* only the calling thread */
114 #endif
115
116 #define MAX_PATH (2 * K)
117
118 #define MAX_SECS 100000000
119
120 // for timer info max values which include all bits
121 #define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF)
122
123 #define LARGEPAGES_BIT (1 << 6)
124 ////////////////////////////////////////////////////////////////////////////////
125 // global variables
126 julong os::Linux::_physical_memory = 0;
127
128 address os::Linux::_initial_thread_stack_bottom = NULL;
129 uintptr_t os::Linux::_initial_thread_stack_size = 0;
130
131 int (*os::Linux::_clock_gettime)(clockid_t, struct timespec *) = NULL;
132 int (*os::Linux::_pthread_getcpuclockid)(pthread_t, clockid_t *) = NULL;
133 int (*os::Linux::_pthread_setname_np)(pthread_t, const char*) = NULL;
134 Mutex* os::Linux::_createThread_lock = NULL;
135 pthread_t os::Linux::_main_thread;
136 int os::Linux::_page_size = -1;
137 const int os::Linux::_vm_default_page_size = (8 * K);
138 bool os::Linux::_is_floating_stack = false;
139 bool os::Linux::_is_NPTL = false;
140 bool os::Linux::_supports_fast_thread_cpu_time = false;
141 const char * os::Linux::_glibc_version = NULL;
142 const char * os::Linux::_libpthread_version = NULL;
143 pthread_condattr_t os::Linux::_condattr[1];
144
145 static jlong initial_time_count=0;
146
147 static int clock_tics_per_sec = 100;
148
149 // For diagnostics to print a message once. see run_periodic_checks
150 static sigset_t check_signal_done;
151 static bool check_signals = true;
152
153 static pid_t _initial_pid = 0;
154
155 // Signal number used to suspend/resume a thread
156
157 // do not use any signal number less than SIGSEGV, see 4355769
158 static int SR_signum = SIGUSR2;
159 sigset_t SR_sigset;
160
161 // Used to protect dlsym() calls
162 static pthread_mutex_t dl_mutex;
163
164 // Declarations
165 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time);
166
167 // utility functions
168
169 static int SR_initialize();
170
171 julong os::available_memory() {
172 return Linux::available_memory();
173 }
174
175 julong os::Linux::available_memory() {
176 // values in struct sysinfo are "unsigned long"
177 struct sysinfo si;
178 sysinfo(&si);
179
180 return (julong)si.freeram * si.mem_unit;
181 }
182
183 julong os::physical_memory() {
184 return Linux::physical_memory();
185 }
186
187 // Return true if user is running as root.
188
189 bool os::have_special_privileges() {
190 static bool init = false;
191 static bool privileges = false;
192 if (!init) {
193 privileges = (getuid() != geteuid()) || (getgid() != getegid());
194 init = true;
195 }
196 return privileges;
197 }
198
199
200 #ifndef SYS_gettid
201 // i386: 224, ia64: 1105, amd64: 186, sparc 143
202 #ifdef __ia64__
203 #define SYS_gettid 1105
204 #elif __i386__
205 #define SYS_gettid 224
206 #elif __amd64__
207 #define SYS_gettid 186
208 #elif __sparc__
209 #define SYS_gettid 143
210 #else
211 #error define gettid for the arch
212 #endif
213 #endif
214
215 // Cpu architecture string
216 static char cpu_arch[] = HOTSPOT_LIB_ARCH;
217
218
219 // pid_t gettid()
220 //
221 // Returns the kernel thread id of the currently running thread. Kernel
222 // thread id is used to access /proc.
223 //
224 // (Note that getpid() on LinuxThreads returns kernel thread id too; but
225 // on NPTL, it returns the same pid for all threads, as required by POSIX.)
226 //
227 pid_t os::Linux::gettid() {
228 int rslt = syscall(SYS_gettid);
229 if (rslt == -1) {
230 // old kernel, no NPTL support
231 return getpid();
232 } else {
233 return (pid_t)rslt;
234 }
235 }
236
237 // Most versions of linux have a bug where the number of processors are
238 // determined by looking at the /proc file system. In a chroot environment,
239 // the system call returns 1. This causes the VM to act as if it is
240 // a single processor and elide locking (see is_MP() call).
241 static bool unsafe_chroot_detected = false;
242 static const char *unstable_chroot_error = "/proc file system not found.\n"
243 "Java may be unstable running multithreaded in a chroot "
244 "environment on Linux when /proc filesystem is not mounted.";
245
246 void os::Linux::initialize_system_info() {
247 set_processor_count(sysconf(_SC_NPROCESSORS_CONF));
248 if (processor_count() == 1) {
249 pid_t pid = os::Linux::gettid();
250 char fname[32];
251 jio_snprintf(fname, sizeof(fname), "/proc/%d", pid);
252 FILE *fp = fopen(fname, "r");
253 if (fp == NULL) {
254 unsafe_chroot_detected = true;
255 } else {
256 fclose(fp);
257 }
258 }
259 _physical_memory = (julong)sysconf(_SC_PHYS_PAGES) * (julong)sysconf(_SC_PAGESIZE);
260 assert(processor_count() > 0, "linux error");
261 }
262
263 void os::init_system_properties_values() {
264 // The next steps are taken in the product version:
265 //
266 // Obtain the JAVA_HOME value from the location of libjvm.so.
267 // This library should be located at:
268 // <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm.so.
269 //
270 // If "/jre/lib/" appears at the right place in the path, then we
271 // assume libjvm.so is installed in a JDK and we use this path.
272 //
273 // Otherwise exit with message: "Could not create the Java virtual machine."
274 //
275 // The following extra steps are taken in the debugging version:
276 //
277 // If "/jre/lib/" does NOT appear at the right place in the path
278 // instead of exit check for $JAVA_HOME environment variable.
279 //
280 // If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>,
281 // then we append a fake suffix "hotspot/libjvm.so" to this path so
282 // it looks like libjvm.so is installed there
283 // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm.so.
284 //
285 // Otherwise exit.
286 //
287 // Important note: if the location of libjvm.so changes this
288 // code needs to be changed accordingly.
289
290 // See ld(1):
291 // The linker uses the following search paths to locate required
292 // shared libraries:
293 // 1: ...
294 // ...
295 // 7: The default directories, normally /lib and /usr/lib.
296 #if defined(AMD64) || defined(_LP64) && (defined(SPARC) || defined(PPC) || defined(S390))
297 #define DEFAULT_LIBPATH "/usr/lib64:/lib64:/lib:/usr/lib"
298 #else
299 #define DEFAULT_LIBPATH "/lib:/usr/lib"
300 #endif
301
302 // Base path of extensions installed on the system.
303 #define SYS_EXT_DIR "/usr/java/packages"
304 #define EXTENSIONS_DIR "/lib/ext"
305
306 // Buffer that fits several sprintfs.
307 // Note that the space for the colon and the trailing null are provided
308 // by the nulls included by the sizeof operator.
309 const size_t bufsize =
310 MAX2((size_t)MAXPATHLEN, // For dll_dir & friends.
311 (size_t)MAXPATHLEN + sizeof(EXTENSIONS_DIR) + sizeof(SYS_EXT_DIR) + sizeof(EXTENSIONS_DIR)); // extensions dir
312 char *buf = (char *)NEW_C_HEAP_ARRAY(char, bufsize, mtInternal);
313
314 // sysclasspath, java_home, dll_dir
315 {
316 char *pslash;
317 os::jvm_path(buf, bufsize);
318
319 // Found the full path to libjvm.so.
320 // Now cut the path to <java_home>/jre if we can.
321 pslash = strrchr(buf, '/');
322 if (pslash != NULL) {
323 *pslash = '\0'; // Get rid of /libjvm.so.
324 }
325 pslash = strrchr(buf, '/');
326 if (pslash != NULL) {
327 *pslash = '\0'; // Get rid of /{client|server|hotspot}.
328 }
329 Arguments::set_dll_dir(buf);
330
331 if (pslash != NULL) {
332 pslash = strrchr(buf, '/');
333 if (pslash != NULL) {
334 *pslash = '\0'; // Get rid of /<arch>.
335 pslash = strrchr(buf, '/');
336 if (pslash != NULL) {
337 *pslash = '\0'; // Get rid of /lib.
338 }
339 }
340 }
341 Arguments::set_java_home(buf);
342 set_boot_path('/', ':');
343 }
344
345 // Where to look for native libraries.
346 //
347 // Note: Due to a legacy implementation, most of the library path
348 // is set in the launcher. This was to accomodate linking restrictions
349 // on legacy Linux implementations (which are no longer supported).
350 // Eventually, all the library path setting will be done here.
351 //
352 // However, to prevent the proliferation of improperly built native
353 // libraries, the new path component /usr/java/packages is added here.
354 // Eventually, all the library path setting will be done here.
355 {
356 // Get the user setting of LD_LIBRARY_PATH, and prepended it. It
357 // should always exist (until the legacy problem cited above is
358 // addressed).
359 const char *v = ::getenv("LD_LIBRARY_PATH");
360 const char *v_colon = ":";
361 if (v == NULL) { v = ""; v_colon = ""; }
362 // That's +1 for the colon and +1 for the trailing '\0'.
363 char *ld_library_path = (char *)NEW_C_HEAP_ARRAY(char,
364 strlen(v) + 1 +
365 sizeof(SYS_EXT_DIR) + sizeof("/lib/") + strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH) + 1,
366 mtInternal);
367 sprintf(ld_library_path, "%s%s" SYS_EXT_DIR "/lib/%s:" DEFAULT_LIBPATH, v, v_colon, cpu_arch);
368 Arguments::set_library_path(ld_library_path);
369 FREE_C_HEAP_ARRAY(char, ld_library_path);
370 }
371
372 // Extensions directories.
373 sprintf(buf, "%s" EXTENSIONS_DIR ":" SYS_EXT_DIR EXTENSIONS_DIR, Arguments::get_java_home());
374 Arguments::set_ext_dirs(buf);
375
376 FREE_C_HEAP_ARRAY(char, buf);
377
378 #undef DEFAULT_LIBPATH
379 #undef SYS_EXT_DIR
380 #undef EXTENSIONS_DIR
381 }
382
383 ////////////////////////////////////////////////////////////////////////////////
384 // breakpoint support
385
386 void os::breakpoint() {
387 BREAKPOINT;
388 }
389
390 extern "C" void breakpoint() {
391 // use debugger to set breakpoint here
392 }
393
394 ////////////////////////////////////////////////////////////////////////////////
395 // signal support
396
397 debug_only(static bool signal_sets_initialized = false);
398 static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs;
399
400 bool os::Linux::is_sig_ignored(int sig) {
401 struct sigaction oact;
402 sigaction(sig, (struct sigaction*)NULL, &oact);
403 void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*, oact.sa_sigaction)
404 : CAST_FROM_FN_PTR(void*, oact.sa_handler);
405 if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN)) {
406 return true;
407 } else {
408 return false;
409 }
410 }
411
412 void os::Linux::signal_sets_init() {
413 // Should also have an assertion stating we are still single-threaded.
414 assert(!signal_sets_initialized, "Already initialized");
415 // Fill in signals that are necessarily unblocked for all threads in
416 // the VM. Currently, we unblock the following signals:
417 // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden
418 // by -Xrs (=ReduceSignalUsage));
419 // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all
420 // other threads. The "ReduceSignalUsage" boolean tells us not to alter
421 // the dispositions or masks wrt these signals.
422 // Programs embedding the VM that want to use the above signals for their
423 // own purposes must, at this time, use the "-Xrs" option to prevent
424 // interference with shutdown hooks and BREAK_SIGNAL thread dumping.
425 // (See bug 4345157, and other related bugs).
426 // In reality, though, unblocking these signals is really a nop, since
427 // these signals are not blocked by default.
428 sigemptyset(&unblocked_sigs);
429 sigemptyset(&allowdebug_blocked_sigs);
430 sigaddset(&unblocked_sigs, SIGILL);
431 sigaddset(&unblocked_sigs, SIGSEGV);
432 sigaddset(&unblocked_sigs, SIGBUS);
433 sigaddset(&unblocked_sigs, SIGFPE);
434 #if defined(PPC64)
435 sigaddset(&unblocked_sigs, SIGTRAP);
436 #endif
437 sigaddset(&unblocked_sigs, SR_signum);
438
439 if (!ReduceSignalUsage) {
440 if (!os::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) {
441 sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL);
442 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL);
443 }
444 if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) {
445 sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL);
446 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL);
447 }
448 if (!os::Linux::is_sig_ignored(SHUTDOWN3_SIGNAL)) {
449 sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL);
450 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN3_SIGNAL);
451 }
452 }
453 // Fill in signals that are blocked by all but the VM thread.
454 sigemptyset(&vm_sigs);
455 if (!ReduceSignalUsage) {
456 sigaddset(&vm_sigs, BREAK_SIGNAL);
457 }
458 debug_only(signal_sets_initialized = true);
459
460 }
461
462 // These are signals that are unblocked while a thread is running Java.
463 // (For some reason, they get blocked by default.)
464 sigset_t* os::Linux::unblocked_signals() {
465 assert(signal_sets_initialized, "Not initialized");
466 return &unblocked_sigs;
467 }
468
469 // These are the signals that are blocked while a (non-VM) thread is
470 // running Java. Only the VM thread handles these signals.
471 sigset_t* os::Linux::vm_signals() {
472 assert(signal_sets_initialized, "Not initialized");
473 return &vm_sigs;
474 }
475
476 // These are signals that are blocked during cond_wait to allow debugger in
477 sigset_t* os::Linux::allowdebug_blocked_signals() {
478 assert(signal_sets_initialized, "Not initialized");
479 return &allowdebug_blocked_sigs;
480 }
481
482 void os::Linux::hotspot_sigmask(Thread* thread) {
483
484 //Save caller's signal mask before setting VM signal mask
485 sigset_t caller_sigmask;
486 pthread_sigmask(SIG_BLOCK, NULL, &caller_sigmask);
487
488 OSThread* osthread = thread->osthread();
489 osthread->set_caller_sigmask(caller_sigmask);
490
491 pthread_sigmask(SIG_UNBLOCK, os::Linux::unblocked_signals(), NULL);
492
493 if (!ReduceSignalUsage) {
494 if (thread->is_VM_thread()) {
495 // Only the VM thread handles BREAK_SIGNAL ...
496 pthread_sigmask(SIG_UNBLOCK, vm_signals(), NULL);
497 } else {
498 // ... all other threads block BREAK_SIGNAL
499 pthread_sigmask(SIG_BLOCK, vm_signals(), NULL);
500 }
501 }
502 }
503
504 //////////////////////////////////////////////////////////////////////////////
505 // detecting pthread library
506
507 void os::Linux::libpthread_init() {
508 // Save glibc and pthread version strings. Note that _CS_GNU_LIBC_VERSION
509 // and _CS_GNU_LIBPTHREAD_VERSION are supported in glibc >= 2.3.2. Use a
510 // generic name for earlier versions.
511 // Define macros here so we can build HotSpot on old systems.
512 #ifndef _CS_GNU_LIBC_VERSION
513 #define _CS_GNU_LIBC_VERSION 2
514 #endif
515 #ifndef _CS_GNU_LIBPTHREAD_VERSION
516 #define _CS_GNU_LIBPTHREAD_VERSION 3
517 #endif
518
519 size_t n = confstr(_CS_GNU_LIBC_VERSION, NULL, 0);
520 if (n > 0) {
521 char *str = (char *)malloc(n, mtInternal);
522 confstr(_CS_GNU_LIBC_VERSION, str, n);
523 os::Linux::set_glibc_version(str);
524 } else {
525 // _CS_GNU_LIBC_VERSION is not supported, try gnu_get_libc_version()
526 static char _gnu_libc_version[32];
527 jio_snprintf(_gnu_libc_version, sizeof(_gnu_libc_version),
528 "glibc %s %s", gnu_get_libc_version(), gnu_get_libc_release());
529 os::Linux::set_glibc_version(_gnu_libc_version);
530 }
531
532 n = confstr(_CS_GNU_LIBPTHREAD_VERSION, NULL, 0);
533 if (n > 0) {
534 char *str = (char *)malloc(n, mtInternal);
535 confstr(_CS_GNU_LIBPTHREAD_VERSION, str, n);
536 // Vanilla RH-9 (glibc 2.3.2) has a bug that confstr() always tells
537 // us "NPTL-0.29" even we are running with LinuxThreads. Check if this
538 // is the case. LinuxThreads has a hard limit on max number of threads.
539 // So sysconf(_SC_THREAD_THREADS_MAX) will return a positive value.
540 // On the other hand, NPTL does not have such a limit, sysconf()
541 // will return -1 and errno is not changed. Check if it is really NPTL.
542 if (strcmp(os::Linux::glibc_version(), "glibc 2.3.2") == 0 &&
543 strstr(str, "NPTL") &&
544 sysconf(_SC_THREAD_THREADS_MAX) > 0) {
545 free(str);
546 os::Linux::set_libpthread_version("linuxthreads");
547 } else {
548 os::Linux::set_libpthread_version(str);
549 }
550 } else {
551 // glibc before 2.3.2 only has LinuxThreads.
552 os::Linux::set_libpthread_version("linuxthreads");
553 }
554
555 if (strstr(libpthread_version(), "NPTL")) {
556 os::Linux::set_is_NPTL();
557 } else {
558 os::Linux::set_is_LinuxThreads();
559 }
560
561 // LinuxThreads have two flavors: floating-stack mode, which allows variable
562 // stack size; and fixed-stack mode. NPTL is always floating-stack.
563 if (os::Linux::is_NPTL() || os::Linux::supports_variable_stack_size()) {
564 os::Linux::set_is_floating_stack();
565 }
566 }
567
568 /////////////////////////////////////////////////////////////////////////////
569 // thread stack
570
571 // Force Linux kernel to expand current thread stack. If "bottom" is close
572 // to the stack guard, caller should block all signals.
573 //
574 // MAP_GROWSDOWN:
575 // A special mmap() flag that is used to implement thread stacks. It tells
576 // kernel that the memory region should extend downwards when needed. This
577 // allows early versions of LinuxThreads to only mmap the first few pages
578 // when creating a new thread. Linux kernel will automatically expand thread
579 // stack as needed (on page faults).
580 //
581 // However, because the memory region of a MAP_GROWSDOWN stack can grow on
582 // demand, if a page fault happens outside an already mapped MAP_GROWSDOWN
583 // region, it's hard to tell if the fault is due to a legitimate stack
584 // access or because of reading/writing non-exist memory (e.g. buffer
585 // overrun). As a rule, if the fault happens below current stack pointer,
586 // Linux kernel does not expand stack, instead a SIGSEGV is sent to the
587 // application (see Linux kernel fault.c).
588 //
589 // This Linux feature can cause SIGSEGV when VM bangs thread stack for
590 // stack overflow detection.
591 //
592 // Newer version of LinuxThreads (since glibc-2.2, or, RH-7.x) and NPTL do
593 // not use this flag. However, the stack of initial thread is not created
594 // by pthread, it is still MAP_GROWSDOWN. Also it's possible (though
595 // unlikely) that user code can create a thread with MAP_GROWSDOWN stack
596 // and then attach the thread to JVM.
597 //
598 // To get around the problem and allow stack banging on Linux, we need to
599 // manually expand thread stack after receiving the SIGSEGV.
600 //
601 // There are two ways to expand thread stack to address "bottom", we used
602 // both of them in JVM before 1.5:
603 // 1. adjust stack pointer first so that it is below "bottom", and then
604 // touch "bottom"
605 // 2. mmap() the page in question
606 //
607 // Now alternate signal stack is gone, it's harder to use 2. For instance,
608 // if current sp is already near the lower end of page 101, and we need to
609 // call mmap() to map page 100, it is possible that part of the mmap() frame
610 // will be placed in page 100. When page 100 is mapped, it is zero-filled.
611 // That will destroy the mmap() frame and cause VM to crash.
612 //
613 // The following code works by adjusting sp first, then accessing the "bottom"
614 // page to force a page fault. Linux kernel will then automatically expand the
615 // stack mapping.
616 //
617 // _expand_stack_to() assumes its frame size is less than page size, which
618 // should always be true if the function is not inlined.
619
620 #if __GNUC__ < 3 // gcc 2.x does not support noinline attribute
621 #define NOINLINE
622 #else
623 #define NOINLINE __attribute__ ((noinline))
624 #endif
625
626 static void _expand_stack_to(address bottom) NOINLINE;
627
628 static void _expand_stack_to(address bottom) {
629 address sp;
630 size_t size;
631 volatile char *p;
632
633 // Adjust bottom to point to the largest address within the same page, it
634 // gives us a one-page buffer if alloca() allocates slightly more memory.
635 bottom = (address)align_size_down((uintptr_t)bottom, os::Linux::page_size());
636 bottom += os::Linux::page_size() - 1;
637
638 // sp might be slightly above current stack pointer; if that's the case, we
639 // will alloca() a little more space than necessary, which is OK. Don't use
640 // os::current_stack_pointer(), as its result can be slightly below current
641 // stack pointer, causing us to not alloca enough to reach "bottom".
642 sp = (address)&sp;
643
644 if (sp > bottom) {
645 size = sp - bottom;
646 p = (volatile char *)alloca(size);
647 assert(p != NULL && p <= (volatile char *)bottom, "alloca problem?");
648 p[0] = '\0';
649 }
650 }
651
652 bool os::Linux::manually_expand_stack(JavaThread * t, address addr) {
653 assert(t!=NULL, "just checking");
654 assert(t->osthread()->expanding_stack(), "expand should be set");
655 assert(t->stack_base() != NULL, "stack_base was not initialized");
656
657 if (addr < t->stack_base() && addr >= t->stack_yellow_zone_base()) {
658 sigset_t mask_all, old_sigset;
659 sigfillset(&mask_all);
660 pthread_sigmask(SIG_SETMASK, &mask_all, &old_sigset);
661 _expand_stack_to(addr);
662 pthread_sigmask(SIG_SETMASK, &old_sigset, NULL);
663 return true;
664 }
665 return false;
666 }
667
668 //////////////////////////////////////////////////////////////////////////////
669 // create new thread
670
671 static address highest_vm_reserved_address();
672
673 // check if it's safe to start a new thread
674 static bool _thread_safety_check(Thread* thread) {
675 if (os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack()) {
676 // Fixed stack LinuxThreads (SuSE Linux/x86, and some versions of Redhat)
677 // Heap is mmap'ed at lower end of memory space. Thread stacks are
678 // allocated (MAP_FIXED) from high address space. Every thread stack
679 // occupies a fixed size slot (usually 2Mbytes, but user can change
680 // it to other values if they rebuild LinuxThreads).
681 //
682 // Problem with MAP_FIXED is that mmap() can still succeed even part of
683 // the memory region has already been mmap'ed. That means if we have too
684 // many threads and/or very large heap, eventually thread stack will
685 // collide with heap.
686 //
687 // Here we try to prevent heap/stack collision by comparing current
688 // stack bottom with the highest address that has been mmap'ed by JVM
689 // plus a safety margin for memory maps created by native code.
690 //
691 // This feature can be disabled by setting ThreadSafetyMargin to 0
692 //
693 if (ThreadSafetyMargin > 0) {
694 address stack_bottom = os::current_stack_base() - os::current_stack_size();
695
696 // not safe if our stack extends below the safety margin
697 return stack_bottom - ThreadSafetyMargin >= highest_vm_reserved_address();
698 } else {
699 return true;
700 }
701 } else {
702 // Floating stack LinuxThreads or NPTL:
703 // Unlike fixed stack LinuxThreads, thread stacks are not MAP_FIXED. When
704 // there's not enough space left, pthread_create() will fail. If we come
705 // here, that means enough space has been reserved for stack.
706 return true;
707 }
708 }
709
710 // Thread start routine for all newly created threads
711 static void *java_start(Thread *thread) {
712 // Try to randomize the cache line index of hot stack frames.
713 // This helps when threads of the same stack traces evict each other's
714 // cache lines. The threads can be either from the same JVM instance, or
715 // from different JVM instances. The benefit is especially true for
716 // processors with hyperthreading technology.
717 static int counter = 0;
718 int pid = os::current_process_id();
719 alloca(((pid ^ counter++) & 7) * 128);
720
721 ThreadLocalStorage::set_thread(thread);
722
723 OSThread* osthread = thread->osthread();
724 Monitor* sync = osthread->startThread_lock();
725
726 // non floating stack LinuxThreads needs extra check, see above
727 if (!_thread_safety_check(thread)) {
728 // notify parent thread
729 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
730 osthread->set_state(ZOMBIE);
731 sync->notify_all();
732 return NULL;
733 }
734
735 // thread_id is kernel thread id (similar to Solaris LWP id)
736 osthread->set_thread_id(os::Linux::gettid());
737
738 if (UseNUMA) {
739 int lgrp_id = os::numa_get_group_id();
740 if (lgrp_id != -1) {
741 thread->set_lgrp_id(lgrp_id);
742 }
743 }
744 // initialize signal mask for this thread
745 os::Linux::hotspot_sigmask(thread);
746
747 // initialize floating point control register
748 os::Linux::init_thread_fpu_state();
749
750 // handshaking with parent thread
751 {
752 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
753
754 // notify parent thread
755 osthread->set_state(INITIALIZED);
756 sync->notify_all();
757
758 // wait until os::start_thread()
759 while (osthread->get_state() == INITIALIZED) {
760 sync->wait(Mutex::_no_safepoint_check_flag);
761 }
762 }
763
764 // call one more level start routine
765 thread->run();
766
767 return 0;
768 }
769
770 bool os::create_thread(Thread* thread, ThreadType thr_type,
771 size_t stack_size) {
772 assert(thread->osthread() == NULL, "caller responsible");
773
774 // Allocate the OSThread object
775 OSThread* osthread = new OSThread(NULL, NULL);
776 if (osthread == NULL) {
777 return false;
778 }
779
780 // set the correct thread state
781 osthread->set_thread_type(thr_type);
782
783 // Initial state is ALLOCATED but not INITIALIZED
784 osthread->set_state(ALLOCATED);
785
786 thread->set_osthread(osthread);
787
788 // init thread attributes
789 pthread_attr_t attr;
790 pthread_attr_init(&attr);
791 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
792
793 // stack size
794 if (os::Linux::supports_variable_stack_size()) {
795 // calculate stack size if it's not specified by caller
796 if (stack_size == 0) {
797 stack_size = os::Linux::default_stack_size(thr_type);
798
799 switch (thr_type) {
800 case os::java_thread:
801 // Java threads use ThreadStackSize which default value can be
802 // changed with the flag -Xss
803 assert(JavaThread::stack_size_at_create() > 0, "this should be set");
804 stack_size = JavaThread::stack_size_at_create();
805 break;
806 case os::compiler_thread:
807 if (CompilerThreadStackSize > 0) {
808 stack_size = (size_t)(CompilerThreadStackSize * K);
809 break;
810 } // else fall through:
811 // use VMThreadStackSize if CompilerThreadStackSize is not defined
812 case os::vm_thread:
813 case os::pgc_thread:
814 case os::cgc_thread:
815 case os::watcher_thread:
816 if (VMThreadStackSize > 0) stack_size = (size_t)(VMThreadStackSize * K);
817 break;
818 }
819 }
820
821 stack_size = MAX2(stack_size, os::Linux::min_stack_allowed);
822 pthread_attr_setstacksize(&attr, stack_size);
823 } else {
824 // let pthread_create() pick the default value.
825 }
826
827 // glibc guard page
828 pthread_attr_setguardsize(&attr, os::Linux::default_guard_size(thr_type));
829
830 ThreadState state;
831
832 {
833 // Serialize thread creation if we are running with fixed stack LinuxThreads
834 bool lock = os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack();
835 if (lock) {
836 os::Linux::createThread_lock()->lock_without_safepoint_check();
837 }
838
839 pthread_t tid;
840 int ret = pthread_create(&tid, &attr, (void* (*)(void*)) java_start, thread);
841
842 pthread_attr_destroy(&attr);
843
844 if (ret != 0) {
845 if (PrintMiscellaneous && (Verbose || WizardMode)) {
846 perror("pthread_create()");
847 }
848 // Need to clean up stuff we've allocated so far
849 thread->set_osthread(NULL);
850 delete osthread;
851 if (lock) os::Linux::createThread_lock()->unlock();
852 return false;
853 }
854
855 // Store pthread info into the OSThread
856 osthread->set_pthread_id(tid);
857
858 // Wait until child thread is either initialized or aborted
859 {
860 Monitor* sync_with_child = osthread->startThread_lock();
861 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
862 while ((state = osthread->get_state()) == ALLOCATED) {
863 sync_with_child->wait(Mutex::_no_safepoint_check_flag);
864 }
865 }
866
867 if (lock) {
868 os::Linux::createThread_lock()->unlock();
869 }
870 }
871
872 // Aborted due to thread limit being reached
873 if (state == ZOMBIE) {
874 thread->set_osthread(NULL);
875 delete osthread;
876 return false;
877 }
878
879 // The thread is returned suspended (in state INITIALIZED),
880 // and is started higher up in the call chain
881 assert(state == INITIALIZED, "race condition");
882 return true;
883 }
884
885 /////////////////////////////////////////////////////////////////////////////
886 // attach existing thread
887
888 // bootstrap the main thread
889 bool os::create_main_thread(JavaThread* thread) {
890 assert(os::Linux::_main_thread == pthread_self(), "should be called inside main thread");
891 return create_attached_thread(thread);
892 }
893
894 bool os::create_attached_thread(JavaThread* thread) {
895 #ifdef ASSERT
896 thread->verify_not_published();
897 #endif
898
899 // Allocate the OSThread object
900 OSThread* osthread = new OSThread(NULL, NULL);
901
902 if (osthread == NULL) {
903 return false;
904 }
905
906 // Store pthread info into the OSThread
907 osthread->set_thread_id(os::Linux::gettid());
908 osthread->set_pthread_id(::pthread_self());
909
910 // initialize floating point control register
911 os::Linux::init_thread_fpu_state();
912
913 // Initial thread state is RUNNABLE
914 osthread->set_state(RUNNABLE);
915
916 thread->set_osthread(osthread);
917
918 if (UseNUMA) {
919 int lgrp_id = os::numa_get_group_id();
920 if (lgrp_id != -1) {
921 thread->set_lgrp_id(lgrp_id);
922 }
923 }
924
925 if (os::Linux::is_initial_thread()) {
926 // If current thread is initial thread, its stack is mapped on demand,
927 // see notes about MAP_GROWSDOWN. Here we try to force kernel to map
928 // the entire stack region to avoid SEGV in stack banging.
929 // It is also useful to get around the heap-stack-gap problem on SuSE
930 // kernel (see 4821821 for details). We first expand stack to the top
931 // of yellow zone, then enable stack yellow zone (order is significant,
932 // enabling yellow zone first will crash JVM on SuSE Linux), so there
933 // is no gap between the last two virtual memory regions.
934
935 JavaThread *jt = (JavaThread *)thread;
936 address addr = jt->stack_yellow_zone_base();
937 assert(addr != NULL, "initialization problem?");
938 assert(jt->stack_available(addr) > 0, "stack guard should not be enabled");
939
940 osthread->set_expanding_stack();
941 os::Linux::manually_expand_stack(jt, addr);
942 osthread->clear_expanding_stack();
943 }
944
945 // initialize signal mask for this thread
946 // and save the caller's signal mask
947 os::Linux::hotspot_sigmask(thread);
948
949 return true;
950 }
951
952 void os::pd_start_thread(Thread* thread) {
953 OSThread * osthread = thread->osthread();
954 assert(osthread->get_state() != INITIALIZED, "just checking");
955 Monitor* sync_with_child = osthread->startThread_lock();
956 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
957 sync_with_child->notify();
958 }
959
960 // Free Linux resources related to the OSThread
961 void os::free_thread(OSThread* osthread) {
962 assert(osthread != NULL, "osthread not set");
963
964 if (Thread::current()->osthread() == osthread) {
965 // Restore caller's signal mask
966 sigset_t sigmask = osthread->caller_sigmask();
967 pthread_sigmask(SIG_SETMASK, &sigmask, NULL);
968 }
969
970 delete osthread;
971 }
972
973 //////////////////////////////////////////////////////////////////////////////
974 // thread local storage
975
976 // Restore the thread pointer if the destructor is called. This is in case
977 // someone from JNI code sets up a destructor with pthread_key_create to run
978 // detachCurrentThread on thread death. Unless we restore the thread pointer we
979 // will hang or crash. When detachCurrentThread is called the key will be set
980 // to null and we will not be called again. If detachCurrentThread is never
981 // called we could loop forever depending on the pthread implementation.
982 static void restore_thread_pointer(void* p) {
983 Thread* thread = (Thread*) p;
984 os::thread_local_storage_at_put(ThreadLocalStorage::thread_index(), thread);
985 }
986
987 int os::allocate_thread_local_storage() {
988 pthread_key_t key;
989 int rslt = pthread_key_create(&key, restore_thread_pointer);
990 assert(rslt == 0, "cannot allocate thread local storage");
991 return (int)key;
992 }
993
994 // Note: This is currently not used by VM, as we don't destroy TLS key
995 // on VM exit.
996 void os::free_thread_local_storage(int index) {
997 int rslt = pthread_key_delete((pthread_key_t)index);
998 assert(rslt == 0, "invalid index");
999 }
1000
1001 void os::thread_local_storage_at_put(int index, void* value) {
1002 int rslt = pthread_setspecific((pthread_key_t)index, value);
1003 assert(rslt == 0, "pthread_setspecific failed");
1004 }
1005
1006 extern "C" Thread* get_thread() {
1007 return ThreadLocalStorage::thread();
1008 }
1009
1010 //////////////////////////////////////////////////////////////////////////////
1011 // initial thread
1012
1013 // Check if current thread is the initial thread, similar to Solaris thr_main.
1014 bool os::Linux::is_initial_thread(void) {
1015 char dummy;
1016 // If called before init complete, thread stack bottom will be null.
1017 // Can be called if fatal error occurs before initialization.
1018 if (initial_thread_stack_bottom() == NULL) return false;
1019 assert(initial_thread_stack_bottom() != NULL &&
1020 initial_thread_stack_size() != 0,
1021 "os::init did not locate initial thread's stack region");
1022 if ((address)&dummy >= initial_thread_stack_bottom() &&
1023 (address)&dummy < initial_thread_stack_bottom() + initial_thread_stack_size()) {
1024 return true;
1025 } else {
1026 return false;
1027 }
1028 }
1029
1030 // Find the virtual memory area that contains addr
1031 static bool find_vma(address addr, address* vma_low, address* vma_high) {
1032 FILE *fp = fopen("/proc/self/maps", "r");
1033 if (fp) {
1034 address low, high;
1035 while (!feof(fp)) {
1036 if (fscanf(fp, "%p-%p", &low, &high) == 2) {
1037 if (low <= addr && addr < high) {
1038 if (vma_low) *vma_low = low;
1039 if (vma_high) *vma_high = high;
1040 fclose(fp);
1041 return true;
1042 }
1043 }
1044 for (;;) {
1045 int ch = fgetc(fp);
1046 if (ch == EOF || ch == (int)'\n') break;
1047 }
1048 }
1049 fclose(fp);
1050 }
1051 return false;
1052 }
1053
1054 // Locate initial thread stack. This special handling of initial thread stack
1055 // is needed because pthread_getattr_np() on most (all?) Linux distros returns
1056 // bogus value for initial thread.
1057 void os::Linux::capture_initial_stack(size_t max_size) {
1058 // stack size is the easy part, get it from RLIMIT_STACK
1059 size_t stack_size;
1060 struct rlimit rlim;
1061 getrlimit(RLIMIT_STACK, &rlim);
1062 stack_size = rlim.rlim_cur;
1063
1064 // 6308388: a bug in ld.so will relocate its own .data section to the
1065 // lower end of primordial stack; reduce ulimit -s value a little bit
1066 // so we won't install guard page on ld.so's data section.
1067 stack_size -= 2 * page_size();
1068
1069 // 4441425: avoid crash with "unlimited" stack size on SuSE 7.1 or Redhat
1070 // 7.1, in both cases we will get 2G in return value.
1071 // 4466587: glibc 2.2.x compiled w/o "--enable-kernel=2.4.0" (RH 7.0,
1072 // SuSE 7.2, Debian) can not handle alternate signal stack correctly
1073 // for initial thread if its stack size exceeds 6M. Cap it at 2M,
1074 // in case other parts in glibc still assumes 2M max stack size.
1075 // FIXME: alt signal stack is gone, maybe we can relax this constraint?
1076 // Problem still exists RH7.2 (IA64 anyway) but 2MB is a little small
1077 if (stack_size > 2 * K * K IA64_ONLY(*2)) {
1078 stack_size = 2 * K * K IA64_ONLY(*2);
1079 }
1080 // Try to figure out where the stack base (top) is. This is harder.
1081 //
1082 // When an application is started, glibc saves the initial stack pointer in
1083 // a global variable "__libc_stack_end", which is then used by system
1084 // libraries. __libc_stack_end should be pretty close to stack top. The
1085 // variable is available since the very early days. However, because it is
1086 // a private interface, it could disappear in the future.
1087 //
1088 // Linux kernel saves start_stack information in /proc/<pid>/stat. Similar
1089 // to __libc_stack_end, it is very close to stack top, but isn't the real
1090 // stack top. Note that /proc may not exist if VM is running as a chroot
1091 // program, so reading /proc/<pid>/stat could fail. Also the contents of
1092 // /proc/<pid>/stat could change in the future (though unlikely).
1093 //
1094 // We try __libc_stack_end first. If that doesn't work, look for
1095 // /proc/<pid>/stat. If neither of them works, we use current stack pointer
1096 // as a hint, which should work well in most cases.
1097
1098 uintptr_t stack_start;
1099
1100 // try __libc_stack_end first
1101 uintptr_t *p = (uintptr_t *)dlsym(RTLD_DEFAULT, "__libc_stack_end");
1102 if (p && *p) {
1103 stack_start = *p;
1104 } else {
1105 // see if we can get the start_stack field from /proc/self/stat
1106 FILE *fp;
1107 int pid;
1108 char state;
1109 int ppid;
1110 int pgrp;
1111 int session;
1112 int nr;
1113 int tpgrp;
1114 unsigned long flags;
1115 unsigned long minflt;
1116 unsigned long cminflt;
1117 unsigned long majflt;
1118 unsigned long cmajflt;
1119 unsigned long utime;
1120 unsigned long stime;
1121 long cutime;
1122 long cstime;
1123 long prio;
1124 long nice;
1125 long junk;
1126 long it_real;
1127 uintptr_t start;
1128 uintptr_t vsize;
1129 intptr_t rss;
1130 uintptr_t rsslim;
1131 uintptr_t scodes;
1132 uintptr_t ecode;
1133 int i;
1134
1135 // Figure what the primordial thread stack base is. Code is inspired
1136 // by email from Hans Boehm. /proc/self/stat begins with current pid,
1137 // followed by command name surrounded by parentheses, state, etc.
1138 char stat[2048];
1139 int statlen;
1140
1141 fp = fopen("/proc/self/stat", "r");
1142 if (fp) {
1143 statlen = fread(stat, 1, 2047, fp);
1144 stat[statlen] = '\0';
1145 fclose(fp);
1146
1147 // Skip pid and the command string. Note that we could be dealing with
1148 // weird command names, e.g. user could decide to rename java launcher
1149 // to "java 1.4.2 :)", then the stat file would look like
1150 // 1234 (java 1.4.2 :)) R ... ...
1151 // We don't really need to know the command string, just find the last
1152 // occurrence of ")" and then start parsing from there. See bug 4726580.
1153 char * s = strrchr(stat, ')');
1154
1155 i = 0;
1156 if (s) {
1157 // Skip blank chars
1158 do { s++; } while (s && isspace(*s));
1159
1160 #define _UFM UINTX_FORMAT
1161 #define _DFM INTX_FORMAT
1162
1163 // 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2
1164 // 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
1165 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,
1166 &state, // 3 %c
1167 &ppid, // 4 %d
1168 &pgrp, // 5 %d
1169 &session, // 6 %d
1170 &nr, // 7 %d
1171 &tpgrp, // 8 %d
1172 &flags, // 9 %lu
1173 &minflt, // 10 %lu
1174 &cminflt, // 11 %lu
1175 &majflt, // 12 %lu
1176 &cmajflt, // 13 %lu
1177 &utime, // 14 %lu
1178 &stime, // 15 %lu
1179 &cutime, // 16 %ld
1180 &cstime, // 17 %ld
1181 &prio, // 18 %ld
1182 &nice, // 19 %ld
1183 &junk, // 20 %ld
1184 &it_real, // 21 %ld
1185 &start, // 22 UINTX_FORMAT
1186 &vsize, // 23 UINTX_FORMAT
1187 &rss, // 24 INTX_FORMAT
1188 &rsslim, // 25 UINTX_FORMAT
1189 &scodes, // 26 UINTX_FORMAT
1190 &ecode, // 27 UINTX_FORMAT
1191 &stack_start); // 28 UINTX_FORMAT
1192 }
1193
1194 #undef _UFM
1195 #undef _DFM
1196
1197 if (i != 28 - 2) {
1198 assert(false, "Bad conversion from /proc/self/stat");
1199 // product mode - assume we are the initial thread, good luck in the
1200 // embedded case.
1201 warning("Can't detect initial thread stack location - bad conversion");
1202 stack_start = (uintptr_t) &rlim;
1203 }
1204 } else {
1205 // For some reason we can't open /proc/self/stat (for example, running on
1206 // FreeBSD with a Linux emulator, or inside chroot), this should work for
1207 // most cases, so don't abort:
1208 warning("Can't detect initial thread stack location - no /proc/self/stat");
1209 stack_start = (uintptr_t) &rlim;
1210 }
1211 }
1212
1213 // Now we have a pointer (stack_start) very close to the stack top, the
1214 // next thing to do is to figure out the exact location of stack top. We
1215 // can find out the virtual memory area that contains stack_start by
1216 // reading /proc/self/maps, it should be the last vma in /proc/self/maps,
1217 // and its upper limit is the real stack top. (again, this would fail if
1218 // running inside chroot, because /proc may not exist.)
1219
1220 uintptr_t stack_top;
1221 address low, high;
1222 if (find_vma((address)stack_start, &low, &high)) {
1223 // success, "high" is the true stack top. (ignore "low", because initial
1224 // thread stack grows on demand, its real bottom is high - RLIMIT_STACK.)
1225 stack_top = (uintptr_t)high;
1226 } else {
1227 // failed, likely because /proc/self/maps does not exist
1228 warning("Can't detect initial thread stack location - find_vma failed");
1229 // best effort: stack_start is normally within a few pages below the real
1230 // stack top, use it as stack top, and reduce stack size so we won't put
1231 // guard page outside stack.
1232 stack_top = stack_start;
1233 stack_size -= 16 * page_size();
1234 }
1235
1236 // stack_top could be partially down the page so align it
1237 stack_top = align_size_up(stack_top, page_size());
1238
1239 if (max_size && stack_size > max_size) {
1240 _initial_thread_stack_size = max_size;
1241 } else {
1242 _initial_thread_stack_size = stack_size;
1243 }
1244
1245 _initial_thread_stack_size = align_size_down(_initial_thread_stack_size, page_size());
1246 _initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size;
1247 }
1248
1249 ////////////////////////////////////////////////////////////////////////////////
1250 // time support
1251
1252 // Time since start-up in seconds to a fine granularity.
1253 // Used by VMSelfDestructTimer and the MemProfiler.
1254 double os::elapsedTime() {
1255
1256 return ((double)os::elapsed_counter()) / os::elapsed_frequency(); // nanosecond resolution
1257 }
1258
1259 jlong os::elapsed_counter() {
1260 return javaTimeNanos() - initial_time_count;
1261 }
1262
1263 jlong os::elapsed_frequency() {
1264 return NANOSECS_PER_SEC; // nanosecond resolution
1265 }
1266
1267 bool os::supports_vtime() { return true; }
1268 bool os::enable_vtime() { return false; }
1269 bool os::vtime_enabled() { return false; }
1270
1271 double os::elapsedVTime() {
1272 struct rusage usage;
1273 int retval = getrusage(RUSAGE_THREAD, &usage);
1274 if (retval == 0) {
1275 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);
1276 } else {
1277 // better than nothing, but not much
1278 return elapsedTime();
1279 }
1280 }
1281
1282 jlong os::javaTimeMillis() {
1283 timeval time;
1284 int status = gettimeofday(&time, NULL);
1285 assert(status != -1, "linux error");
1286 return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000);
1287 }
1288
1289 void os::javaTimeSystemUTC(jlong &seconds, jlong &nanos) {
1290 timeval time;
1291 int status = gettimeofday(&time, NULL);
1292 assert(status != -1, "linux error");
1293 seconds = jlong(time.tv_sec);
1294 nanos = jlong(time.tv_usec) * 1000;
1295 }
1296
1297
1298 #ifndef CLOCK_MONOTONIC
1299 #define CLOCK_MONOTONIC (1)
1300 #endif
1301
1302 void os::Linux::clock_init() {
1303 // we do dlopen's in this particular order due to bug in linux
1304 // dynamical loader (see 6348968) leading to crash on exit
1305 void* handle = dlopen("librt.so.1", RTLD_LAZY);
1306 if (handle == NULL) {
1307 handle = dlopen("librt.so", RTLD_LAZY);
1308 }
1309
1310 if (handle) {
1311 int (*clock_getres_func)(clockid_t, struct timespec*) =
1312 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres");
1313 int (*clock_gettime_func)(clockid_t, struct timespec*) =
1314 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime");
1315 if (clock_getres_func && clock_gettime_func) {
1316 // See if monotonic clock is supported by the kernel. Note that some
1317 // early implementations simply return kernel jiffies (updated every
1318 // 1/100 or 1/1000 second). It would be bad to use such a low res clock
1319 // for nano time (though the monotonic property is still nice to have).
1320 // It's fixed in newer kernels, however clock_getres() still returns
1321 // 1/HZ. We check if clock_getres() works, but will ignore its reported
1322 // resolution for now. Hopefully as people move to new kernels, this
1323 // won't be a problem.
1324 struct timespec res;
1325 struct timespec tp;
1326 if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 &&
1327 clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) {
1328 // yes, monotonic clock is supported
1329 _clock_gettime = clock_gettime_func;
1330 return;
1331 } else {
1332 // close librt if there is no monotonic clock
1333 dlclose(handle);
1334 }
1335 }
1336 }
1337 warning("No monotonic clock was available - timed services may " \
1338 "be adversely affected if the time-of-day clock changes");
1339 }
1340
1341 #ifndef SYS_clock_getres
1342 #if defined(IA32) || defined(AMD64)
1343 #define SYS_clock_getres IA32_ONLY(266) AMD64_ONLY(229)
1344 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y)
1345 #else
1346 #warning "SYS_clock_getres not defined for this platform, disabling fast_thread_cpu_time"
1347 #define sys_clock_getres(x,y) -1
1348 #endif
1349 #else
1350 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y)
1351 #endif
1352
1353 void os::Linux::fast_thread_clock_init() {
1354 if (!UseLinuxPosixThreadCPUClocks) {
1355 return;
1356 }
1357 clockid_t clockid;
1358 struct timespec tp;
1359 int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) =
1360 (int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid");
1361
1362 // Switch to using fast clocks for thread cpu time if
1363 // the sys_clock_getres() returns 0 error code.
1364 // Note, that some kernels may support the current thread
1365 // clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks
1366 // returned by the pthread_getcpuclockid().
1367 // If the fast Posix clocks are supported then the sys_clock_getres()
1368 // must return at least tp.tv_sec == 0 which means a resolution
1369 // better than 1 sec. This is extra check for reliability.
1370
1371 if (pthread_getcpuclockid_func &&
1372 pthread_getcpuclockid_func(_main_thread, &clockid) == 0 &&
1373 sys_clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) {
1374 _supports_fast_thread_cpu_time = true;
1375 _pthread_getcpuclockid = pthread_getcpuclockid_func;
1376 }
1377 }
1378
1379 jlong os::javaTimeNanos() {
1380 if (os::supports_monotonic_clock()) {
1381 struct timespec tp;
1382 int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp);
1383 assert(status == 0, "gettime error");
1384 jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec);
1385 return result;
1386 } else {
1387 timeval time;
1388 int status = gettimeofday(&time, NULL);
1389 assert(status != -1, "linux error");
1390 jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec);
1391 return 1000 * usecs;
1392 }
1393 }
1394
1395 void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) {
1396 if (os::supports_monotonic_clock()) {
1397 info_ptr->max_value = ALL_64_BITS;
1398
1399 // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past
1400 info_ptr->may_skip_backward = false; // not subject to resetting or drifting
1401 info_ptr->may_skip_forward = false; // not subject to resetting or drifting
1402 } else {
1403 // gettimeofday - based on time in seconds since the Epoch thus does not wrap
1404 info_ptr->max_value = ALL_64_BITS;
1405
1406 // gettimeofday is a real time clock so it skips
1407 info_ptr->may_skip_backward = true;
1408 info_ptr->may_skip_forward = true;
1409 }
1410
1411 info_ptr->kind = JVMTI_TIMER_ELAPSED; // elapsed not CPU time
1412 }
1413
1414 // Return the real, user, and system times in seconds from an
1415 // arbitrary fixed point in the past.
1416 bool os::getTimesSecs(double* process_real_time,
1417 double* process_user_time,
1418 double* process_system_time) {
1419 struct tms ticks;
1420 clock_t real_ticks = times(&ticks);
1421
1422 if (real_ticks == (clock_t) (-1)) {
1423 return false;
1424 } else {
1425 double ticks_per_second = (double) clock_tics_per_sec;
1426 *process_user_time = ((double) ticks.tms_utime) / ticks_per_second;
1427 *process_system_time = ((double) ticks.tms_stime) / ticks_per_second;
1428 *process_real_time = ((double) real_ticks) / ticks_per_second;
1429
1430 return true;
1431 }
1432 }
1433
1434
1435 char * os::local_time_string(char *buf, size_t buflen) {
1436 struct tm t;
1437 time_t long_time;
1438 time(&long_time);
1439 localtime_r(&long_time, &t);
1440 jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d",
1441 t.tm_year + 1900, t.tm_mon + 1, t.tm_mday,
1442 t.tm_hour, t.tm_min, t.tm_sec);
1443 return buf;
1444 }
1445
1446 struct tm* os::localtime_pd(const time_t* clock, struct tm* res) {
1447 return localtime_r(clock, res);
1448 }
1449
1450 ////////////////////////////////////////////////////////////////////////////////
1451 // runtime exit support
1452
1453 // Note: os::shutdown() might be called very early during initialization, or
1454 // called from signal handler. Before adding something to os::shutdown(), make
1455 // sure it is async-safe and can handle partially initialized VM.
1456 void os::shutdown() {
1457
1458 // allow PerfMemory to attempt cleanup of any persistent resources
1459 perfMemory_exit();
1460
1461 // needs to remove object in file system
1462 AttachListener::abort();
1463
1464 // flush buffered output, finish log files
1465 ostream_abort();
1466
1467 // Check for abort hook
1468 abort_hook_t abort_hook = Arguments::abort_hook();
1469 if (abort_hook != NULL) {
1470 abort_hook();
1471 }
1472
1473 }
1474
1475 // Note: os::abort() might be called very early during initialization, or
1476 // called from signal handler. Before adding something to os::abort(), make
1477 // sure it is async-safe and can handle partially initialized VM.
1478 void os::abort(bool dump_core) {
1479 os::shutdown();
1480 if (dump_core) {
1481 #ifndef PRODUCT
1482 fdStream out(defaultStream::output_fd());
1483 out.print_raw("Current thread is ");
1484 char buf[16];
1485 jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id());
1486 out.print_raw_cr(buf);
1487 out.print_raw_cr("Dumping core ...");
1488 #endif
1489 ::abort(); // dump core
1490 }
1491
1492 ::exit(1);
1493 }
1494
1495 // Die immediately, no exit hook, no abort hook, no cleanup.
1496 void os::die() {
1497 // _exit() on LinuxThreads only kills current thread
1498 ::abort();
1499 }
1500
1501
1502 // This method is a copy of JDK's sysGetLastErrorString
1503 // from src/solaris/hpi/src/system_md.c
1504
1505 size_t os::lasterror(char *buf, size_t len) {
1506 if (errno == 0) return 0;
1507
1508 const char *s = ::strerror(errno);
1509 size_t n = ::strlen(s);
1510 if (n >= len) {
1511 n = len - 1;
1512 }
1513 ::strncpy(buf, s, n);
1514 buf[n] = '\0';
1515 return n;
1516 }
1517
1518 intx os::current_thread_id() { return (intx)pthread_self(); }
1519 int os::current_process_id() {
1520
1521 // Under the old linux thread library, linux gives each thread
1522 // its own process id. Because of this each thread will return
1523 // a different pid if this method were to return the result
1524 // of getpid(2). Linux provides no api that returns the pid
1525 // of the launcher thread for the vm. This implementation
1526 // returns a unique pid, the pid of the launcher thread
1527 // that starts the vm 'process'.
1528
1529 // Under the NPTL, getpid() returns the same pid as the
1530 // launcher thread rather than a unique pid per thread.
1531 // Use gettid() if you want the old pre NPTL behaviour.
1532
1533 // if you are looking for the result of a call to getpid() that
1534 // returns a unique pid for the calling thread, then look at the
1535 // OSThread::thread_id() method in osThread_linux.hpp file
1536
1537 return (int)(_initial_pid ? _initial_pid : getpid());
1538 }
1539
1540 // DLL functions
1541
1542 const char* os::dll_file_extension() { return ".so"; }
1543
1544 // This must be hard coded because it's the system's temporary
1545 // directory not the java application's temp directory, ala java.io.tmpdir.
1546 const char* os::get_temp_directory() { return "/tmp"; }
1547
1548 static bool file_exists(const char* filename) {
1549 struct stat statbuf;
1550 if (filename == NULL || strlen(filename) == 0) {
1551 return false;
1552 }
1553 return os::stat(filename, &statbuf) == 0;
1554 }
1555
1556 bool os::dll_build_name(char* buffer, size_t buflen,
1557 const char* pname, const char* fname) {
1558 bool retval = false;
1559 // Copied from libhpi
1560 const size_t pnamelen = pname ? strlen(pname) : 0;
1561
1562 // Return error on buffer overflow.
1563 if (pnamelen + strlen(fname) + 10 > (size_t) buflen) {
1564 return retval;
1565 }
1566
1567 if (pnamelen == 0) {
1568 snprintf(buffer, buflen, "lib%s.so", fname);
1569 retval = true;
1570 } else if (strchr(pname, *os::path_separator()) != NULL) {
1571 int n;
1572 char** pelements = split_path(pname, &n);
1573 if (pelements == NULL) {
1574 return false;
1575 }
1576 for (int i = 0; i < n; i++) {
1577 // Really shouldn't be NULL, but check can't hurt
1578 if (pelements[i] == NULL || strlen(pelements[i]) == 0) {
1579 continue; // skip the empty path values
1580 }
1581 snprintf(buffer, buflen, "%s/lib%s.so", pelements[i], fname);
1582 if (file_exists(buffer)) {
1583 retval = true;
1584 break;
1585 }
1586 }
1587 // release the storage
1588 for (int i = 0; i < n; i++) {
1589 if (pelements[i] != NULL) {
1590 FREE_C_HEAP_ARRAY(char, pelements[i]);
1591 }
1592 }
1593 if (pelements != NULL) {
1594 FREE_C_HEAP_ARRAY(char*, pelements);
1595 }
1596 } else {
1597 snprintf(buffer, buflen, "%s/lib%s.so", pname, fname);
1598 retval = true;
1599 }
1600 return retval;
1601 }
1602
1603 // check if addr is inside libjvm.so
1604 bool os::address_is_in_vm(address addr) {
1605 static address libjvm_base_addr;
1606 Dl_info dlinfo;
1607
1608 if (libjvm_base_addr == NULL) {
1609 if (dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo) != 0) {
1610 libjvm_base_addr = (address)dlinfo.dli_fbase;
1611 }
1612 assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm");
1613 }
1614
1615 if (dladdr((void *)addr, &dlinfo) != 0) {
1616 if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true;
1617 }
1618
1619 return false;
1620 }
1621
1622 bool os::dll_address_to_function_name(address addr, char *buf,
1623 int buflen, int *offset) {
1624 // buf is not optional, but offset is optional
1625 assert(buf != NULL, "sanity check");
1626
1627 Dl_info dlinfo;
1628
1629 if (dladdr((void*)addr, &dlinfo) != 0) {
1630 // see if we have a matching symbol
1631 if (dlinfo.dli_saddr != NULL && dlinfo.dli_sname != NULL) {
1632 if (!Decoder::demangle(dlinfo.dli_sname, buf, buflen)) {
1633 jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname);
1634 }
1635 if (offset != NULL) *offset = addr - (address)dlinfo.dli_saddr;
1636 return true;
1637 }
1638 // no matching symbol so try for just file info
1639 if (dlinfo.dli_fname != NULL && dlinfo.dli_fbase != NULL) {
1640 if (Decoder::decode((address)(addr - (address)dlinfo.dli_fbase),
1641 buf, buflen, offset, dlinfo.dli_fname)) {
1642 return true;
1643 }
1644 }
1645 }
1646
1647 buf[0] = '\0';
1648 if (offset != NULL) *offset = -1;
1649 return false;
1650 }
1651
1652 struct _address_to_library_name {
1653 address addr; // input : memory address
1654 size_t buflen; // size of fname
1655 char* fname; // output: library name
1656 address base; // library base addr
1657 };
1658
1659 static int address_to_library_name_callback(struct dl_phdr_info *info,
1660 size_t size, void *data) {
1661 int i;
1662 bool found = false;
1663 address libbase = NULL;
1664 struct _address_to_library_name * d = (struct _address_to_library_name *)data;
1665
1666 // iterate through all loadable segments
1667 for (i = 0; i < info->dlpi_phnum; i++) {
1668 address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr);
1669 if (info->dlpi_phdr[i].p_type == PT_LOAD) {
1670 // base address of a library is the lowest address of its loaded
1671 // segments.
1672 if (libbase == NULL || libbase > segbase) {
1673 libbase = segbase;
1674 }
1675 // see if 'addr' is within current segment
1676 if (segbase <= d->addr &&
1677 d->addr < segbase + info->dlpi_phdr[i].p_memsz) {
1678 found = true;
1679 }
1680 }
1681 }
1682
1683 // dlpi_name is NULL or empty if the ELF file is executable, return 0
1684 // so dll_address_to_library_name() can fall through to use dladdr() which
1685 // can figure out executable name from argv[0].
1686 if (found && info->dlpi_name && info->dlpi_name[0]) {
1687 d->base = libbase;
1688 if (d->fname) {
1689 jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name);
1690 }
1691 return 1;
1692 }
1693 return 0;
1694 }
1695
1696 bool os::dll_address_to_library_name(address addr, char* buf,
1697 int buflen, int* offset) {
1698 // buf is not optional, but offset is optional
1699 assert(buf != NULL, "sanity check");
1700
1701 Dl_info dlinfo;
1702 struct _address_to_library_name data;
1703
1704 // There is a bug in old glibc dladdr() implementation that it could resolve
1705 // to wrong library name if the .so file has a base address != NULL. Here
1706 // we iterate through the program headers of all loaded libraries to find
1707 // out which library 'addr' really belongs to. This workaround can be
1708 // removed once the minimum requirement for glibc is moved to 2.3.x.
1709 data.addr = addr;
1710 data.fname = buf;
1711 data.buflen = buflen;
1712 data.base = NULL;
1713 int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data);
1714
1715 if (rslt) {
1716 // buf already contains library name
1717 if (offset) *offset = addr - data.base;
1718 return true;
1719 }
1720 if (dladdr((void*)addr, &dlinfo) != 0) {
1721 if (dlinfo.dli_fname != NULL) {
1722 jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname);
1723 }
1724 if (dlinfo.dli_fbase != NULL && offset != NULL) {
1725 *offset = addr - (address)dlinfo.dli_fbase;
1726 }
1727 return true;
1728 }
1729
1730 buf[0] = '\0';
1731 if (offset) *offset = -1;
1732 return false;
1733 }
1734
1735 // Loads .dll/.so and
1736 // in case of error it checks if .dll/.so was built for the
1737 // same architecture as Hotspot is running on
1738
1739
1740 // Remember the stack's state. The Linux dynamic linker will change
1741 // the stack to 'executable' at most once, so we must safepoint only once.
1742 bool os::Linux::_stack_is_executable = false;
1743
1744 // VM operation that loads a library. This is necessary if stack protection
1745 // of the Java stacks can be lost during loading the library. If we
1746 // do not stop the Java threads, they can stack overflow before the stacks
1747 // are protected again.
1748 class VM_LinuxDllLoad: public VM_Operation {
1749 private:
1750 const char *_filename;
1751 char *_ebuf;
1752 int _ebuflen;
1753 void *_lib;
1754 public:
1755 VM_LinuxDllLoad(const char *fn, char *ebuf, int ebuflen) :
1756 _filename(fn), _ebuf(ebuf), _ebuflen(ebuflen), _lib(NULL) {}
1757 VMOp_Type type() const { return VMOp_LinuxDllLoad; }
1758 void doit() {
1759 _lib = os::Linux::dll_load_in_vmthread(_filename, _ebuf, _ebuflen);
1760 os::Linux::_stack_is_executable = true;
1761 }
1762 void* loaded_library() { return _lib; }
1763 };
1764
1765 void * os::dll_load(const char *filename, char *ebuf, int ebuflen) {
1766 void * result = NULL;
1767 bool load_attempted = false;
1768
1769 // Check whether the library to load might change execution rights
1770 // of the stack. If they are changed, the protection of the stack
1771 // guard pages will be lost. We need a safepoint to fix this.
1772 //
1773 // See Linux man page execstack(8) for more info.
1774 if (os::uses_stack_guard_pages() && !os::Linux::_stack_is_executable) {
1775 ElfFile ef(filename);
1776 if (!ef.specifies_noexecstack()) {
1777 if (!is_init_completed()) {
1778 os::Linux::_stack_is_executable = true;
1779 // This is OK - No Java threads have been created yet, and hence no
1780 // stack guard pages to fix.
1781 //
1782 // This should happen only when you are building JDK7 using a very
1783 // old version of JDK6 (e.g., with JPRT) and running test_gamma.
1784 //
1785 // Dynamic loader will make all stacks executable after
1786 // this function returns, and will not do that again.
1787 assert(Threads::first() == NULL, "no Java threads should exist yet.");
1788 } else {
1789 warning("You have loaded library %s which might have disabled stack guard. "
1790 "The VM will try to fix the stack guard now.\n"
1791 "It's highly recommended that you fix the library with "
1792 "'execstack -c <libfile>', or link it with '-z noexecstack'.",
1793 filename);
1794
1795 assert(Thread::current()->is_Java_thread(), "must be Java thread");
1796 JavaThread *jt = JavaThread::current();
1797 if (jt->thread_state() != _thread_in_native) {
1798 // This happens when a compiler thread tries to load a hsdis-<arch>.so file
1799 // that requires ExecStack. Cannot enter safe point. Let's give up.
1800 warning("Unable to fix stack guard. Giving up.");
1801 } else {
1802 if (!LoadExecStackDllInVMThread) {
1803 // This is for the case where the DLL has an static
1804 // constructor function that executes JNI code. We cannot
1805 // load such DLLs in the VMThread.
1806 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen);
1807 }
1808
1809 ThreadInVMfromNative tiv(jt);
1810 debug_only(VMNativeEntryWrapper vew;)
1811
1812 VM_LinuxDllLoad op(filename, ebuf, ebuflen);
1813 VMThread::execute(&op);
1814 if (LoadExecStackDllInVMThread) {
1815 result = op.loaded_library();
1816 }
1817 load_attempted = true;
1818 }
1819 }
1820 }
1821 }
1822
1823 if (!load_attempted) {
1824 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen);
1825 }
1826
1827 if (result != NULL) {
1828 // Successful loading
1829 return result;
1830 }
1831
1832 Elf32_Ehdr elf_head;
1833 int diag_msg_max_length=ebuflen-strlen(ebuf);
1834 char* diag_msg_buf=ebuf+strlen(ebuf);
1835
1836 if (diag_msg_max_length==0) {
1837 // No more space in ebuf for additional diagnostics message
1838 return NULL;
1839 }
1840
1841
1842 int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK);
1843
1844 if (file_descriptor < 0) {
1845 // Can't open library, report dlerror() message
1846 return NULL;
1847 }
1848
1849 bool failed_to_read_elf_head=
1850 (sizeof(elf_head)!=
1851 (::read(file_descriptor, &elf_head,sizeof(elf_head))));
1852
1853 ::close(file_descriptor);
1854 if (failed_to_read_elf_head) {
1855 // file i/o error - report dlerror() msg
1856 return NULL;
1857 }
1858
1859 typedef struct {
1860 Elf32_Half code; // Actual value as defined in elf.h
1861 Elf32_Half compat_class; // Compatibility of archs at VM's sense
1862 char elf_class; // 32 or 64 bit
1863 char endianess; // MSB or LSB
1864 char* name; // String representation
1865 } arch_t;
1866
1867 #ifndef EM_486
1868 #define EM_486 6 /* Intel 80486 */
1869 #endif
1870 #ifndef EM_AARCH64
1871 #define EM_AARCH64 183 /* ARM AARCH64 */
1872 #endif
1873
1874 static const arch_t arch_array[]={
1875 {EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
1876 {EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
1877 {EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"},
1878 {EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"},
1879 {EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
1880 {EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
1881 {EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"},
1882 {EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"},
1883 #if defined(VM_LITTLE_ENDIAN)
1884 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2LSB, (char*)"Power PC 64"},
1885 #else
1886 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"},
1887 #endif
1888 {EM_ARM, EM_ARM, ELFCLASS32, ELFDATA2LSB, (char*)"ARM"},
1889 {EM_S390, EM_S390, ELFCLASSNONE, ELFDATA2MSB, (char*)"IBM System/390"},
1890 {EM_ALPHA, EM_ALPHA, ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"},
1891 {EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"},
1892 {EM_MIPS, EM_MIPS, ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"},
1893 {EM_PARISC, EM_PARISC, ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"},
1894 {EM_68K, EM_68K, ELFCLASS32, ELFDATA2MSB, (char*)"M68k"},
1895 {EM_AARCH64, EM_AARCH64, ELFCLASS64, ELFDATA2LSB, (char*)"AARCH64"},
1896 };
1897
1898 #if (defined IA32)
1899 static Elf32_Half running_arch_code=EM_386;
1900 #elif (defined AMD64)
1901 static Elf32_Half running_arch_code=EM_X86_64;
1902 #elif (defined IA64)
1903 static Elf32_Half running_arch_code=EM_IA_64;
1904 #elif (defined __sparc) && (defined _LP64)
1905 static Elf32_Half running_arch_code=EM_SPARCV9;
1906 #elif (defined __sparc) && (!defined _LP64)
1907 static Elf32_Half running_arch_code=EM_SPARC;
1908 #elif (defined __powerpc64__)
1909 static Elf32_Half running_arch_code=EM_PPC64;
1910 #elif (defined __powerpc__)
1911 static Elf32_Half running_arch_code=EM_PPC;
1912 #elif (defined ARM)
1913 static Elf32_Half running_arch_code=EM_ARM;
1914 #elif (defined S390)
1915 static Elf32_Half running_arch_code=EM_S390;
1916 #elif (defined ALPHA)
1917 static Elf32_Half running_arch_code=EM_ALPHA;
1918 #elif (defined MIPSEL)
1919 static Elf32_Half running_arch_code=EM_MIPS_RS3_LE;
1920 #elif (defined PARISC)
1921 static Elf32_Half running_arch_code=EM_PARISC;
1922 #elif (defined MIPS)
1923 static Elf32_Half running_arch_code=EM_MIPS;
1924 #elif (defined M68K)
1925 static Elf32_Half running_arch_code=EM_68K;
1926 #elif (defined AARCH64)
1927 static Elf32_Half running_arch_code=EM_AARCH64;
1928 #else
1929 #error Method os::dll_load requires that one of following is defined:\
1930 IA32, AMD64, IA64, __sparc, __powerpc__, ARM, S390, ALPHA, MIPS, MIPSEL, PARISC, M68K, AARCH64
1931 #endif
1932
1933 // Identify compatability class for VM's architecture and library's architecture
1934 // Obtain string descriptions for architectures
1935
1936 arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL};
1937 int running_arch_index=-1;
1938
1939 for (unsigned int i=0; i < ARRAY_SIZE(arch_array); i++) {
1940 if (running_arch_code == arch_array[i].code) {
1941 running_arch_index = i;
1942 }
1943 if (lib_arch.code == arch_array[i].code) {
1944 lib_arch.compat_class = arch_array[i].compat_class;
1945 lib_arch.name = arch_array[i].name;
1946 }
1947 }
1948
1949 assert(running_arch_index != -1,
1950 "Didn't find running architecture code (running_arch_code) in arch_array");
1951 if (running_arch_index == -1) {
1952 // Even though running architecture detection failed
1953 // we may still continue with reporting dlerror() message
1954 return NULL;
1955 }
1956
1957 if (lib_arch.endianess != arch_array[running_arch_index].endianess) {
1958 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)");
1959 return NULL;
1960 }
1961
1962 #ifndef S390
1963 if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) {
1964 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)");
1965 return NULL;
1966 }
1967 #endif // !S390
1968
1969 if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) {
1970 if (lib_arch.name!=NULL) {
1971 ::snprintf(diag_msg_buf, diag_msg_max_length-1,
1972 " (Possible cause: can't load %s-bit .so on a %s-bit platform)",
1973 lib_arch.name, arch_array[running_arch_index].name);
1974 } else {
1975 ::snprintf(diag_msg_buf, diag_msg_max_length-1,
1976 " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)",
1977 lib_arch.code,
1978 arch_array[running_arch_index].name);
1979 }
1980 }
1981
1982 return NULL;
1983 }
1984
1985 void * os::Linux::dlopen_helper(const char *filename, char *ebuf,
1986 int ebuflen) {
1987 void * result = ::dlopen(filename, RTLD_LAZY);
1988 if (result == NULL) {
1989 ::strncpy(ebuf, ::dlerror(), ebuflen - 1);
1990 ebuf[ebuflen-1] = '\0';
1991 }
1992 return result;
1993 }
1994
1995 void * os::Linux::dll_load_in_vmthread(const char *filename, char *ebuf,
1996 int ebuflen) {
1997 void * result = NULL;
1998 if (LoadExecStackDllInVMThread) {
1999 result = dlopen_helper(filename, ebuf, ebuflen);
2000 }
2001
2002 // Since 7019808, libjvm.so is linked with -noexecstack. If the VM loads a
2003 // library that requires an executable stack, or which does not have this
2004 // stack attribute set, dlopen changes the stack attribute to executable. The
2005 // read protection of the guard pages gets lost.
2006 //
2007 // Need to check _stack_is_executable again as multiple VM_LinuxDllLoad
2008 // may have been queued at the same time.
2009
2010 if (!_stack_is_executable) {
2011 JavaThread *jt = Threads::first();
2012
2013 while (jt) {
2014 if (!jt->stack_guard_zone_unused() && // Stack not yet fully initialized
2015 jt->stack_yellow_zone_enabled()) { // No pending stack overflow exceptions
2016 if (!os::guard_memory((char *) jt->stack_red_zone_base() - jt->stack_red_zone_size(),
2017 jt->stack_yellow_zone_size() + jt->stack_red_zone_size())) {
2018 warning("Attempt to reguard stack yellow zone failed.");
2019 }
2020 }
2021 jt = jt->next();
2022 }
2023 }
2024
2025 return result;
2026 }
2027
2028 // glibc-2.0 libdl is not MT safe. If you are building with any glibc,
2029 // chances are you might want to run the generated bits against glibc-2.0
2030 // libdl.so, so always use locking for any version of glibc.
2031 //
2032 void* os::dll_lookup(void* handle, const char* name) {
2033 pthread_mutex_lock(&dl_mutex);
2034 void* res = dlsym(handle, name);
2035 pthread_mutex_unlock(&dl_mutex);
2036 return res;
2037 }
2038
2039 void* os::get_default_process_handle() {
2040 return (void*)::dlopen(NULL, RTLD_LAZY);
2041 }
2042
2043 static bool _print_ascii_file(const char* filename, outputStream* st) {
2044 int fd = ::open(filename, O_RDONLY);
2045 if (fd == -1) {
2046 return false;
2047 }
2048
2049 char buf[32];
2050 int bytes;
2051 while ((bytes = ::read(fd, buf, sizeof(buf))) > 0) {
2052 st->print_raw(buf, bytes);
2053 }
2054
2055 ::close(fd);
2056
2057 return true;
2058 }
2059
2060 void os::print_dll_info(outputStream *st) {
2061 st->print_cr("Dynamic libraries:");
2062
2063 char fname[32];
2064 pid_t pid = os::Linux::gettid();
2065
2066 jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid);
2067
2068 if (!_print_ascii_file(fname, st)) {
2069 st->print("Can not get library information for pid = %d\n", pid);
2070 }
2071 }
2072
2073 int os::get_loaded_modules_info(os::LoadedModulesCallbackFunc callback, void *param) {
2074 FILE *procmapsFile = NULL;
2075
2076 // Open the procfs maps file for the current process
2077 if ((procmapsFile = fopen("/proc/self/maps", "r")) != NULL) {
2078 // Allocate PATH_MAX for file name plus a reasonable size for other fields.
2079 char line[PATH_MAX + 100];
2080
2081 // Read line by line from 'file'
2082 while (fgets(line, sizeof(line), procmapsFile) != NULL) {
2083 u8 base, top, offset, inode;
2084 char permissions[5];
2085 char device[6];
2086 char name[PATH_MAX + 1];
2087
2088 // Parse fields from line
2089 sscanf(line, "%lx-%lx %4s %lx %5s %ld %s", &base, &top, permissions, &offset, device, &inode, name);
2090
2091 // Filter by device id '00:00' so that we only get file system mapped files.
2092 if (strcmp(device, "00:00") != 0) {
2093
2094 // Call callback with the fields of interest
2095 if(callback(name, (address)base, (address)top, param)) {
2096 // Oops abort, callback aborted
2097 fclose(procmapsFile);
2098 return 1;
2099 }
2100 }
2101 }
2102 fclose(procmapsFile);
2103 }
2104 return 0;
2105 }
2106
2107 void os::print_os_info_brief(outputStream* st) {
2108 os::Linux::print_distro_info(st);
2109
2110 os::Posix::print_uname_info(st);
2111
2112 os::Linux::print_libversion_info(st);
2113
2114 }
2115
2116 void os::print_os_info(outputStream* st) {
2117 st->print("OS:");
2118
2119 os::Linux::print_distro_info(st);
2120
2121 os::Posix::print_uname_info(st);
2122
2123 // Print warning if unsafe chroot environment detected
2124 if (unsafe_chroot_detected) {
2125 st->print("WARNING!! ");
2126 st->print_cr("%s", unstable_chroot_error);
2127 }
2128
2129 os::Linux::print_libversion_info(st);
2130
2131 os::Posix::print_rlimit_info(st);
2132
2133 os::Posix::print_load_average(st);
2134
2135 os::Linux::print_full_memory_info(st);
2136 }
2137
2138 // Try to identify popular distros.
2139 // Most Linux distributions have a /etc/XXX-release file, which contains
2140 // the OS version string. Newer Linux distributions have a /etc/lsb-release
2141 // file that also contains the OS version string. Some have more than one
2142 // /etc/XXX-release file (e.g. Mandrake has both /etc/mandrake-release and
2143 // /etc/redhat-release.), so the order is important.
2144 // Any Linux that is based on Redhat (i.e. Oracle, Mandrake, Sun JDS...) have
2145 // their own specific XXX-release file as well as a redhat-release file.
2146 // Because of this the XXX-release file needs to be searched for before the
2147 // redhat-release file.
2148 // Since Red Hat has a lsb-release file that is not very descriptive the
2149 // search for redhat-release needs to be before lsb-release.
2150 // Since the lsb-release file is the new standard it needs to be searched
2151 // before the older style release files.
2152 // Searching system-release (Red Hat) and os-release (other Linuxes) are a
2153 // next to last resort. The os-release file is a new standard that contains
2154 // distribution information and the system-release file seems to be an old
2155 // standard that has been replaced by the lsb-release and os-release files.
2156 // Searching for the debian_version file is the last resort. It contains
2157 // an informative string like "6.0.6" or "wheezy/sid". Because of this
2158 // "Debian " is printed before the contents of the debian_version file.
2159 void os::Linux::print_distro_info(outputStream* st) {
2160 if (!_print_ascii_file("/etc/oracle-release", st) &&
2161 !_print_ascii_file("/etc/mandriva-release", st) &&
2162 !_print_ascii_file("/etc/mandrake-release", st) &&
2163 !_print_ascii_file("/etc/sun-release", st) &&
2164 !_print_ascii_file("/etc/redhat-release", st) &&
2165 !_print_ascii_file("/etc/lsb-release", st) &&
2166 !_print_ascii_file("/etc/SuSE-release", st) &&
2167 !_print_ascii_file("/etc/turbolinux-release", st) &&
2168 !_print_ascii_file("/etc/gentoo-release", st) &&
2169 !_print_ascii_file("/etc/ltib-release", st) &&
2170 !_print_ascii_file("/etc/angstrom-version", st) &&
2171 !_print_ascii_file("/etc/system-release", st) &&
2172 !_print_ascii_file("/etc/os-release", st)) {
2173
2174 if (file_exists("/etc/debian_version")) {
2175 st->print("Debian ");
2176 _print_ascii_file("/etc/debian_version", st);
2177 } else {
2178 st->print("Linux");
2179 }
2180 }
2181 st->cr();
2182 }
2183
2184 void os::Linux::print_libversion_info(outputStream* st) {
2185 // libc, pthread
2186 st->print("libc:");
2187 st->print("%s ", os::Linux::glibc_version());
2188 st->print("%s ", os::Linux::libpthread_version());
2189 if (os::Linux::is_LinuxThreads()) {
2190 st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed");
2191 }
2192 st->cr();
2193 }
2194
2195 void os::Linux::print_full_memory_info(outputStream* st) {
2196 st->print("\n/proc/meminfo:\n");
2197 _print_ascii_file("/proc/meminfo", st);
2198 st->cr();
2199 }
2200
2201 void os::print_memory_info(outputStream* st) {
2202
2203 st->print("Memory:");
2204 st->print(" %dk page", os::vm_page_size()>>10);
2205
2206 // values in struct sysinfo are "unsigned long"
2207 struct sysinfo si;
2208 sysinfo(&si);
2209
2210 st->print(", physical " UINT64_FORMAT "k",
2211 os::physical_memory() >> 10);
2212 st->print("(" UINT64_FORMAT "k free)",
2213 os::available_memory() >> 10);
2214 st->print(", swap " UINT64_FORMAT "k",
2215 ((jlong)si.totalswap * si.mem_unit) >> 10);
2216 st->print("(" UINT64_FORMAT "k free)",
2217 ((jlong)si.freeswap * si.mem_unit) >> 10);
2218 st->cr();
2219 }
2220
2221 void os::pd_print_cpu_info(outputStream* st) {
2222 st->print("\n/proc/cpuinfo:\n");
2223 if (!_print_ascii_file("/proc/cpuinfo", st)) {
2224 st->print(" <Not Available>");
2225 }
2226 st->cr();
2227 }
2228
2229 void os::print_siginfo(outputStream* st, void* siginfo) {
2230 const siginfo_t* si = (const siginfo_t*)siginfo;
2231
2232 os::Posix::print_siginfo_brief(st, si);
2233 #if INCLUDE_CDS
2234 if (si && (si->si_signo == SIGBUS || si->si_signo == SIGSEGV) &&
2235 UseSharedSpaces) {
2236 FileMapInfo* mapinfo = FileMapInfo::current_info();
2237 if (mapinfo->is_in_shared_space(si->si_addr)) {
2238 st->print("\n\nError accessing class data sharing archive." \
2239 " Mapped file inaccessible during execution, " \
2240 " possible disk/network problem.");
2241 }
2242 }
2243 #endif
2244 st->cr();
2245 }
2246
2247
2248 static void print_signal_handler(outputStream* st, int sig,
2249 char* buf, size_t buflen);
2250
2251 void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) {
2252 st->print_cr("Signal Handlers:");
2253 print_signal_handler(st, SIGSEGV, buf, buflen);
2254 print_signal_handler(st, SIGBUS , buf, buflen);
2255 print_signal_handler(st, SIGFPE , buf, buflen);
2256 print_signal_handler(st, SIGPIPE, buf, buflen);
2257 print_signal_handler(st, SIGXFSZ, buf, buflen);
2258 print_signal_handler(st, SIGILL , buf, buflen);
2259 print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen);
2260 print_signal_handler(st, SR_signum, buf, buflen);
2261 print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen);
2262 print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen);
2263 print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen);
2264 print_signal_handler(st, BREAK_SIGNAL, buf, buflen);
2265 #if defined(PPC64)
2266 print_signal_handler(st, SIGTRAP, buf, buflen);
2267 #endif
2268 }
2269
2270 static char saved_jvm_path[MAXPATHLEN] = {0};
2271
2272 // Find the full path to the current module, libjvm.so
2273 void os::jvm_path(char *buf, jint buflen) {
2274 // Error checking.
2275 if (buflen < MAXPATHLEN) {
2276 assert(false, "must use a large-enough buffer");
2277 buf[0] = '\0';
2278 return;
2279 }
2280 // Lazy resolve the path to current module.
2281 if (saved_jvm_path[0] != 0) {
2282 strcpy(buf, saved_jvm_path);
2283 return;
2284 }
2285
2286 char dli_fname[MAXPATHLEN];
2287 bool ret = dll_address_to_library_name(
2288 CAST_FROM_FN_PTR(address, os::jvm_path),
2289 dli_fname, sizeof(dli_fname), NULL);
2290 assert(ret, "cannot locate libjvm");
2291 char *rp = NULL;
2292 if (ret && dli_fname[0] != '\0') {
2293 rp = realpath(dli_fname, buf);
2294 }
2295 if (rp == NULL) {
2296 return;
2297 }
2298
2299 if (Arguments::sun_java_launcher_is_altjvm()) {
2300 // Support for the java launcher's '-XXaltjvm=<path>' option. Typical
2301 // value for buf is "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so".
2302 // If "/jre/lib/" appears at the right place in the string, then
2303 // assume we are installed in a JDK and we're done. Otherwise, check
2304 // for a JAVA_HOME environment variable and fix up the path so it
2305 // looks like libjvm.so is installed there (append a fake suffix
2306 // hotspot/libjvm.so).
2307 const char *p = buf + strlen(buf) - 1;
2308 for (int count = 0; p > buf && count < 5; ++count) {
2309 for (--p; p > buf && *p != '/'; --p)
2310 /* empty */ ;
2311 }
2312
2313 if (strncmp(p, "/jre/lib/", 9) != 0) {
2314 // Look for JAVA_HOME in the environment.
2315 char* java_home_var = ::getenv("JAVA_HOME");
2316 if (java_home_var != NULL && java_home_var[0] != 0) {
2317 char* jrelib_p;
2318 int len;
2319
2320 // Check the current module name "libjvm.so".
2321 p = strrchr(buf, '/');
2322 if (p == NULL) {
2323 return;
2324 }
2325 assert(strstr(p, "/libjvm") == p, "invalid library name");
2326
2327 rp = realpath(java_home_var, buf);
2328 if (rp == NULL) {
2329 return;
2330 }
2331
2332 // determine if this is a legacy image or modules image
2333 // modules image doesn't have "jre" subdirectory
2334 len = strlen(buf);
2335 assert(len < buflen, "Ran out of buffer room");
2336 jrelib_p = buf + len;
2337 snprintf(jrelib_p, buflen-len, "/jre/lib/%s", cpu_arch);
2338 if (0 != access(buf, F_OK)) {
2339 snprintf(jrelib_p, buflen-len, "/lib/%s", cpu_arch);
2340 }
2341
2342 if (0 == access(buf, F_OK)) {
2343 // Use current module name "libjvm.so"
2344 len = strlen(buf);
2345 snprintf(buf + len, buflen-len, "/hotspot/libjvm.so");
2346 } else {
2347 // Go back to path of .so
2348 rp = realpath(dli_fname, buf);
2349 if (rp == NULL) {
2350 return;
2351 }
2352 }
2353 }
2354 }
2355 }
2356
2357 strncpy(saved_jvm_path, buf, MAXPATHLEN);
2358 saved_jvm_path[MAXPATHLEN - 1] = '\0';
2359 }
2360
2361 void os::print_jni_name_prefix_on(outputStream* st, int args_size) {
2362 // no prefix required, not even "_"
2363 }
2364
2365 void os::print_jni_name_suffix_on(outputStream* st, int args_size) {
2366 // no suffix required
2367 }
2368
2369 ////////////////////////////////////////////////////////////////////////////////
2370 // sun.misc.Signal support
2371
2372 static volatile jint sigint_count = 0;
2373
2374 static void UserHandler(int sig, void *siginfo, void *context) {
2375 // 4511530 - sem_post is serialized and handled by the manager thread. When
2376 // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We
2377 // don't want to flood the manager thread with sem_post requests.
2378 if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1) {
2379 return;
2380 }
2381
2382 // Ctrl-C is pressed during error reporting, likely because the error
2383 // handler fails to abort. Let VM die immediately.
2384 if (sig == SIGINT && is_error_reported()) {
2385 os::die();
2386 }
2387
2388 os::signal_notify(sig);
2389 }
2390
2391 void* os::user_handler() {
2392 return CAST_FROM_FN_PTR(void*, UserHandler);
2393 }
2394
2395 class Semaphore : public StackObj {
2396 public:
2397 Semaphore();
2398 ~Semaphore();
2399 void signal();
2400 void wait();
2401 bool trywait();
2402 bool timedwait(unsigned int sec, int nsec);
2403 private:
2404 sem_t _semaphore;
2405 };
2406
2407 Semaphore::Semaphore() {
2408 sem_init(&_semaphore, 0, 0);
2409 }
2410
2411 Semaphore::~Semaphore() {
2412 sem_destroy(&_semaphore);
2413 }
2414
2415 void Semaphore::signal() {
2416 sem_post(&_semaphore);
2417 }
2418
2419 void Semaphore::wait() {
2420 sem_wait(&_semaphore);
2421 }
2422
2423 bool Semaphore::trywait() {
2424 return sem_trywait(&_semaphore) == 0;
2425 }
2426
2427 bool Semaphore::timedwait(unsigned int sec, int nsec) {
2428
2429 struct timespec ts;
2430 // Semaphore's are always associated with CLOCK_REALTIME
2431 os::Linux::clock_gettime(CLOCK_REALTIME, &ts);
2432 // see unpackTime for discussion on overflow checking
2433 if (sec >= MAX_SECS) {
2434 ts.tv_sec += MAX_SECS;
2435 ts.tv_nsec = 0;
2436 } else {
2437 ts.tv_sec += sec;
2438 ts.tv_nsec += nsec;
2439 if (ts.tv_nsec >= NANOSECS_PER_SEC) {
2440 ts.tv_nsec -= NANOSECS_PER_SEC;
2441 ++ts.tv_sec; // note: this must be <= max_secs
2442 }
2443 }
2444
2445 while (1) {
2446 int result = sem_timedwait(&_semaphore, &ts);
2447 if (result == 0) {
2448 return true;
2449 } else if (errno == EINTR) {
2450 continue;
2451 } else if (errno == ETIMEDOUT) {
2452 return false;
2453 } else {
2454 return false;
2455 }
2456 }
2457 }
2458
2459 extern "C" {
2460 typedef void (*sa_handler_t)(int);
2461 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *);
2462 }
2463
2464 void* os::signal(int signal_number, void* handler) {
2465 struct sigaction sigAct, oldSigAct;
2466
2467 sigfillset(&(sigAct.sa_mask));
2468 sigAct.sa_flags = SA_RESTART|SA_SIGINFO;
2469 sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler);
2470
2471 if (sigaction(signal_number, &sigAct, &oldSigAct)) {
2472 // -1 means registration failed
2473 return (void *)-1;
2474 }
2475
2476 return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler);
2477 }
2478
2479 void os::signal_raise(int signal_number) {
2480 ::raise(signal_number);
2481 }
2482
2483 // The following code is moved from os.cpp for making this
2484 // code platform specific, which it is by its very nature.
2485
2486 // Will be modified when max signal is changed to be dynamic
2487 int os::sigexitnum_pd() {
2488 return NSIG;
2489 }
2490
2491 // a counter for each possible signal value
2492 static volatile jint pending_signals[NSIG+1] = { 0 };
2493
2494 // Linux(POSIX) specific hand shaking semaphore.
2495 static sem_t sig_sem;
2496 static Semaphore sr_semaphore;
2497
2498 void os::signal_init_pd() {
2499 // Initialize signal structures
2500 ::memset((void*)pending_signals, 0, sizeof(pending_signals));
2501
2502 // Initialize signal semaphore
2503 ::sem_init(&sig_sem, 0, 0);
2504 }
2505
2506 void os::signal_notify(int sig) {
2507 Atomic::inc(&pending_signals[sig]);
2508 ::sem_post(&sig_sem);
2509 }
2510
2511 static int check_pending_signals(bool wait) {
2512 Atomic::store(0, &sigint_count);
2513 for (;;) {
2514 for (int i = 0; i < NSIG + 1; i++) {
2515 jint n = pending_signals[i];
2516 if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) {
2517 return i;
2518 }
2519 }
2520 if (!wait) {
2521 return -1;
2522 }
2523 JavaThread *thread = JavaThread::current();
2524 ThreadBlockInVM tbivm(thread);
2525
2526 bool threadIsSuspended;
2527 do {
2528 thread->set_suspend_equivalent();
2529 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
2530 ::sem_wait(&sig_sem);
2531
2532 // were we externally suspended while we were waiting?
2533 threadIsSuspended = thread->handle_special_suspend_equivalent_condition();
2534 if (threadIsSuspended) {
2535 // The semaphore has been incremented, but while we were waiting
2536 // another thread suspended us. We don't want to continue running
2537 // while suspended because that would surprise the thread that
2538 // suspended us.
2539 ::sem_post(&sig_sem);
2540
2541 thread->java_suspend_self();
2542 }
2543 } while (threadIsSuspended);
2544 }
2545 }
2546
2547 int os::signal_lookup() {
2548 return check_pending_signals(false);
2549 }
2550
2551 int os::signal_wait() {
2552 return check_pending_signals(true);
2553 }
2554
2555 ////////////////////////////////////////////////////////////////////////////////
2556 // Virtual Memory
2557
2558 int os::vm_page_size() {
2559 // Seems redundant as all get out
2560 assert(os::Linux::page_size() != -1, "must call os::init");
2561 return os::Linux::page_size();
2562 }
2563
2564 // Solaris allocates memory by pages.
2565 int os::vm_allocation_granularity() {
2566 assert(os::Linux::page_size() != -1, "must call os::init");
2567 return os::Linux::page_size();
2568 }
2569
2570 // Rationale behind this function:
2571 // current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable
2572 // mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get
2573 // samples for JITted code. Here we create private executable mapping over the code cache
2574 // and then we can use standard (well, almost, as mapping can change) way to provide
2575 // info for the reporting script by storing timestamp and location of symbol
2576 void linux_wrap_code(char* base, size_t size) {
2577 static volatile jint cnt = 0;
2578
2579 if (!UseOprofile) {
2580 return;
2581 }
2582
2583 char buf[PATH_MAX+1];
2584 int num = Atomic::add(1, &cnt);
2585
2586 snprintf(buf, sizeof(buf), "%s/hs-vm-%d-%d",
2587 os::get_temp_directory(), os::current_process_id(), num);
2588 unlink(buf);
2589
2590 int fd = ::open(buf, O_CREAT | O_RDWR, S_IRWXU);
2591
2592 if (fd != -1) {
2593 off_t rv = ::lseek(fd, size-2, SEEK_SET);
2594 if (rv != (off_t)-1) {
2595 if (::write(fd, "", 1) == 1) {
2596 mmap(base, size,
2597 PROT_READ|PROT_WRITE|PROT_EXEC,
2598 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0);
2599 }
2600 }
2601 ::close(fd);
2602 unlink(buf);
2603 }
2604 }
2605
2606 static bool recoverable_mmap_error(int err) {
2607 // See if the error is one we can let the caller handle. This
2608 // list of errno values comes from JBS-6843484. I can't find a
2609 // Linux man page that documents this specific set of errno
2610 // values so while this list currently matches Solaris, it may
2611 // change as we gain experience with this failure mode.
2612 switch (err) {
2613 case EBADF:
2614 case EINVAL:
2615 case ENOTSUP:
2616 // let the caller deal with these errors
2617 return true;
2618
2619 default:
2620 // Any remaining errors on this OS can cause our reserved mapping
2621 // to be lost. That can cause confusion where different data
2622 // structures think they have the same memory mapped. The worst
2623 // scenario is if both the VM and a library think they have the
2624 // same memory mapped.
2625 return false;
2626 }
2627 }
2628
2629 static void warn_fail_commit_memory(char* addr, size_t size, bool exec,
2630 int err) {
2631 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT
2632 ", %d) failed; error='%s' (errno=%d)", addr, size, exec,
2633 strerror(err), err);
2634 }
2635
2636 static void warn_fail_commit_memory(char* addr, size_t size,
2637 size_t alignment_hint, bool exec,
2638 int err) {
2639 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT
2640 ", " SIZE_FORMAT ", %d) failed; error='%s' (errno=%d)", addr, size,
2641 alignment_hint, exec, strerror(err), err);
2642 }
2643
2644 // NOTE: Linux kernel does not really reserve the pages for us.
2645 // All it does is to check if there are enough free pages
2646 // left at the time of mmap(). This could be a potential
2647 // problem.
2648 int os::Linux::commit_memory_impl(char* addr, size_t size, bool exec) {
2649 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
2650 uintptr_t res = (uintptr_t) ::mmap(addr, size, prot,
2651 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0);
2652 if (res != (uintptr_t) MAP_FAILED) {
2653 if (UseNUMAInterleaving) {
2654 numa_make_global(addr, size);
2655 }
2656 return 0;
2657 }
2658
2659 int err = errno; // save errno from mmap() call above
2660
2661 if (!recoverable_mmap_error(err)) {
2662 warn_fail_commit_memory(addr, size, exec, err);
2663 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, "committing reserved memory.");
2664 }
2665
2666 return err;
2667 }
2668
2669 bool os::pd_commit_memory(char* addr, size_t size, bool exec) {
2670 return os::Linux::commit_memory_impl(addr, size, exec) == 0;
2671 }
2672
2673 void os::pd_commit_memory_or_exit(char* addr, size_t size, bool exec,
2674 const char* mesg) {
2675 assert(mesg != NULL, "mesg must be specified");
2676 int err = os::Linux::commit_memory_impl(addr, size, 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, exec, err);
2680 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg);
2681 }
2682 }
2683
2684 // Define MAP_HUGETLB here so we can build HotSpot on old systems.
2685 #ifndef MAP_HUGETLB
2686 #define MAP_HUGETLB 0x40000
2687 #endif
2688
2689 // Define MADV_HUGEPAGE here so we can build HotSpot on old systems.
2690 #ifndef MADV_HUGEPAGE
2691 #define MADV_HUGEPAGE 14
2692 #endif
2693
2694 int os::Linux::commit_memory_impl(char* addr, size_t size,
2695 size_t alignment_hint, bool exec) {
2696 int err = os::Linux::commit_memory_impl(addr, size, exec);
2697 if (err == 0) {
2698 realign_memory(addr, size, alignment_hint);
2699 }
2700 return err;
2701 }
2702
2703 bool os::pd_commit_memory(char* addr, size_t size, size_t alignment_hint,
2704 bool exec) {
2705 return os::Linux::commit_memory_impl(addr, size, alignment_hint, exec) == 0;
2706 }
2707
2708 void os::pd_commit_memory_or_exit(char* addr, size_t size,
2709 size_t alignment_hint, bool exec,
2710 const char* mesg) {
2711 assert(mesg != NULL, "mesg must be specified");
2712 int err = os::Linux::commit_memory_impl(addr, size, alignment_hint, exec);
2713 if (err != 0) {
2714 // the caller wants all commit errors to exit with the specified mesg:
2715 warn_fail_commit_memory(addr, size, alignment_hint, exec, err);
2716 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg);
2717 }
2718 }
2719
2720 void os::pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint) {
2721 if (UseTransparentHugePages && alignment_hint > (size_t)vm_page_size()) {
2722 // We don't check the return value: madvise(MADV_HUGEPAGE) may not
2723 // be supported or the memory may already be backed by huge pages.
2724 ::madvise(addr, bytes, MADV_HUGEPAGE);
2725 }
2726 }
2727
2728 void os::pd_free_memory(char *addr, size_t bytes, size_t alignment_hint) {
2729 // This method works by doing an mmap over an existing mmaping and effectively discarding
2730 // the existing pages. However it won't work for SHM-based large pages that cannot be
2731 // uncommitted at all. We don't do anything in this case to avoid creating a segment with
2732 // small pages on top of the SHM segment. This method always works for small pages, so we
2733 // allow that in any case.
2734 if (alignment_hint <= (size_t)os::vm_page_size() || can_commit_large_page_memory()) {
2735 commit_memory(addr, bytes, alignment_hint, !ExecMem);
2736 }
2737 }
2738
2739 void os::numa_make_global(char *addr, size_t bytes) {
2740 Linux::numa_interleave_memory(addr, bytes);
2741 }
2742
2743 // Define for numa_set_bind_policy(int). Setting the argument to 0 will set the
2744 // bind policy to MPOL_PREFERRED for the current thread.
2745 #define USE_MPOL_PREFERRED 0
2746
2747 void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) {
2748 // To make NUMA and large pages more robust when both enabled, we need to ease
2749 // the requirements on where the memory should be allocated. MPOL_BIND is the
2750 // default policy and it will force memory to be allocated on the specified
2751 // node. Changing this to MPOL_PREFERRED will prefer to allocate the memory on
2752 // the specified node, but will not force it. Using this policy will prevent
2753 // getting SIGBUS when trying to allocate large pages on NUMA nodes with no
2754 // free large pages.
2755 Linux::numa_set_bind_policy(USE_MPOL_PREFERRED);
2756 Linux::numa_tonode_memory(addr, bytes, lgrp_hint);
2757 }
2758
2759 bool os::numa_topology_changed() { return false; }
2760
2761 size_t os::numa_get_groups_num() {
2762 int max_node = Linux::numa_max_node();
2763 return max_node > 0 ? max_node + 1 : 1;
2764 }
2765
2766 int os::numa_get_group_id() {
2767 int cpu_id = Linux::sched_getcpu();
2768 if (cpu_id != -1) {
2769 int lgrp_id = Linux::get_node_by_cpu(cpu_id);
2770 if (lgrp_id != -1) {
2771 return lgrp_id;
2772 }
2773 }
2774 return 0;
2775 }
2776
2777 size_t os::numa_get_leaf_groups(int *ids, size_t size) {
2778 for (size_t i = 0; i < size; i++) {
2779 ids[i] = i;
2780 }
2781 return size;
2782 }
2783
2784 bool os::get_page_info(char *start, page_info* info) {
2785 return false;
2786 }
2787
2788 char *os::scan_pages(char *start, char* end, page_info* page_expected,
2789 page_info* page_found) {
2790 return end;
2791 }
2792
2793
2794 int os::Linux::sched_getcpu_syscall(void) {
2795 unsigned int cpu;
2796 int retval = -1;
2797
2798 #if defined(IA32)
2799 #ifndef SYS_getcpu
2800 #define SYS_getcpu 318
2801 #endif
2802 retval = syscall(SYS_getcpu, &cpu, NULL, NULL);
2803 #elif defined(AMD64)
2804 // Unfortunately we have to bring all these macros here from vsyscall.h
2805 // to be able to compile on old linuxes.
2806 #define __NR_vgetcpu 2
2807 #define VSYSCALL_START (-10UL << 20)
2808 #define VSYSCALL_SIZE 1024
2809 #define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr))
2810 typedef long (*vgetcpu_t)(unsigned int *cpu, unsigned int *node, unsigned long *tcache);
2811 vgetcpu_t vgetcpu = (vgetcpu_t)VSYSCALL_ADDR(__NR_vgetcpu);
2812 retval = vgetcpu(&cpu, NULL, NULL);
2813 #endif
2814
2815 return (retval == -1) ? retval : cpu;
2816 }
2817
2818 // Something to do with the numa-aware allocator needs these symbols
2819 extern "C" JNIEXPORT void numa_warn(int number, char *where, ...) { }
2820 extern "C" JNIEXPORT void numa_error(char *where) { }
2821 extern "C" JNIEXPORT int fork1() { return fork(); }
2822
2823
2824 // If we are running with libnuma version > 2, then we should
2825 // be trying to use symbols with versions 1.1
2826 // If we are running with earlier version, which did not have symbol versions,
2827 // we should use the base version.
2828 void* os::Linux::libnuma_dlsym(void* handle, const char *name) {
2829 void *f = dlvsym(handle, name, "libnuma_1.1");
2830 if (f == NULL) {
2831 f = dlsym(handle, name);
2832 }
2833 return f;
2834 }
2835
2836 bool os::Linux::libnuma_init() {
2837 // sched_getcpu() should be in libc.
2838 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t,
2839 dlsym(RTLD_DEFAULT, "sched_getcpu")));
2840
2841 // If it's not, try a direct syscall.
2842 if (sched_getcpu() == -1) {
2843 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t,
2844 (void*)&sched_getcpu_syscall));
2845 }
2846
2847 if (sched_getcpu() != -1) { // Does it work?
2848 void *handle = dlopen("libnuma.so.1", RTLD_LAZY);
2849 if (handle != NULL) {
2850 set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t,
2851 libnuma_dlsym(handle, "numa_node_to_cpus")));
2852 set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t,
2853 libnuma_dlsym(handle, "numa_max_node")));
2854 set_numa_available(CAST_TO_FN_PTR(numa_available_func_t,
2855 libnuma_dlsym(handle, "numa_available")));
2856 set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t,
2857 libnuma_dlsym(handle, "numa_tonode_memory")));
2858 set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t,
2859 libnuma_dlsym(handle, "numa_interleave_memory")));
2860 set_numa_set_bind_policy(CAST_TO_FN_PTR(numa_set_bind_policy_func_t,
2861 libnuma_dlsym(handle, "numa_set_bind_policy")));
2862
2863
2864 if (numa_available() != -1) {
2865 set_numa_all_nodes((unsigned long*)libnuma_dlsym(handle, "numa_all_nodes"));
2866 // Create a cpu -> node mapping
2867 _cpu_to_node = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<int>(0, true);
2868 rebuild_cpu_to_node_map();
2869 return true;
2870 }
2871 }
2872 }
2873 return false;
2874 }
2875
2876 // rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id.
2877 // The table is later used in get_node_by_cpu().
2878 void os::Linux::rebuild_cpu_to_node_map() {
2879 const size_t NCPUS = 32768; // Since the buffer size computation is very obscure
2880 // in libnuma (possible values are starting from 16,
2881 // and continuing up with every other power of 2, but less
2882 // than the maximum number of CPUs supported by kernel), and
2883 // is a subject to change (in libnuma version 2 the requirements
2884 // are more reasonable) we'll just hardcode the number they use
2885 // in the library.
2886 const size_t BitsPerCLong = sizeof(long) * CHAR_BIT;
2887
2888 size_t cpu_num = os::active_processor_count();
2889 size_t cpu_map_size = NCPUS / BitsPerCLong;
2890 size_t cpu_map_valid_size =
2891 MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size);
2892
2893 cpu_to_node()->clear();
2894 cpu_to_node()->at_grow(cpu_num - 1);
2895 size_t node_num = numa_get_groups_num();
2896
2897 unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size, mtInternal);
2898 for (size_t i = 0; i < node_num; i++) {
2899 if (numa_node_to_cpus(i, cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) {
2900 for (size_t j = 0; j < cpu_map_valid_size; j++) {
2901 if (cpu_map[j] != 0) {
2902 for (size_t k = 0; k < BitsPerCLong; k++) {
2903 if (cpu_map[j] & (1UL << k)) {
2904 cpu_to_node()->at_put(j * BitsPerCLong + k, i);
2905 }
2906 }
2907 }
2908 }
2909 }
2910 }
2911 FREE_C_HEAP_ARRAY(unsigned long, cpu_map);
2912 }
2913
2914 int os::Linux::get_node_by_cpu(int cpu_id) {
2915 if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) {
2916 return cpu_to_node()->at(cpu_id);
2917 }
2918 return -1;
2919 }
2920
2921 GrowableArray<int>* os::Linux::_cpu_to_node;
2922 os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu;
2923 os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus;
2924 os::Linux::numa_max_node_func_t os::Linux::_numa_max_node;
2925 os::Linux::numa_available_func_t os::Linux::_numa_available;
2926 os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory;
2927 os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory;
2928 os::Linux::numa_set_bind_policy_func_t os::Linux::_numa_set_bind_policy;
2929 unsigned long* os::Linux::_numa_all_nodes;
2930
2931 bool os::pd_uncommit_memory(char* addr, size_t size) {
2932 uintptr_t res = (uintptr_t) ::mmap(addr, size, PROT_NONE,
2933 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0);
2934 return res != (uintptr_t) MAP_FAILED;
2935 }
2936
2937 static address get_stack_commited_bottom(address bottom, size_t size) {
2938 address nbot = bottom;
2939 address ntop = bottom + size;
2940
2941 size_t page_sz = os::vm_page_size();
2942 unsigned pages = size / page_sz;
2943
2944 unsigned char vec[1];
2945 unsigned imin = 1, imax = pages + 1, imid;
2946 int mincore_return_value = 0;
2947
2948 assert(imin <= imax, "Unexpected page size");
2949
2950 while (imin < imax) {
2951 imid = (imax + imin) / 2;
2952 nbot = ntop - (imid * page_sz);
2953
2954 // Use a trick with mincore to check whether the page is mapped or not.
2955 // mincore sets vec to 1 if page resides in memory and to 0 if page
2956 // is swapped output but if page we are asking for is unmapped
2957 // it returns -1,ENOMEM
2958 mincore_return_value = mincore(nbot, page_sz, vec);
2959
2960 if (mincore_return_value == -1) {
2961 // Page is not mapped go up
2962 // to find first mapped page
2963 if (errno != EAGAIN) {
2964 assert(errno == ENOMEM, "Unexpected mincore errno");
2965 imax = imid;
2966 }
2967 } else {
2968 // Page is mapped go down
2969 // to find first not mapped page
2970 imin = imid + 1;
2971 }
2972 }
2973
2974 nbot = nbot + page_sz;
2975
2976 // Adjust stack bottom one page up if last checked page is not mapped
2977 if (mincore_return_value == -1) {
2978 nbot = nbot + page_sz;
2979 }
2980
2981 return nbot;
2982 }
2983
2984
2985 // Linux uses a growable mapping for the stack, and if the mapping for
2986 // the stack guard pages is not removed when we detach a thread the
2987 // stack cannot grow beyond the pages where the stack guard was
2988 // mapped. If at some point later in the process the stack expands to
2989 // that point, the Linux kernel cannot expand the stack any further
2990 // because the guard pages are in the way, and a segfault occurs.
2991 //
2992 // However, it's essential not to split the stack region by unmapping
2993 // a region (leaving a hole) that's already part of the stack mapping,
2994 // so if the stack mapping has already grown beyond the guard pages at
2995 // the time we create them, we have to truncate the stack mapping.
2996 // So, we need to know the extent of the stack mapping when
2997 // create_stack_guard_pages() is called.
2998
2999 // We only need this for stacks that are growable: at the time of
3000 // writing thread stacks don't use growable mappings (i.e. those
3001 // creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this
3002 // only applies to the main thread.
3003
3004 // If the (growable) stack mapping already extends beyond the point
3005 // where we're going to put our guard pages, truncate the mapping at
3006 // that point by munmap()ping it. This ensures that when we later
3007 // munmap() the guard pages we don't leave a hole in the stack
3008 // mapping. This only affects the main/initial thread
3009
3010 bool os::pd_create_stack_guard_pages(char* addr, size_t size) {
3011 if (os::Linux::is_initial_thread()) {
3012 // As we manually grow stack up to bottom inside create_attached_thread(),
3013 // it's likely that os::Linux::initial_thread_stack_bottom is mapped and
3014 // we don't need to do anything special.
3015 // Check it first, before calling heavy function.
3016 uintptr_t stack_extent = (uintptr_t) os::Linux::initial_thread_stack_bottom();
3017 unsigned char vec[1];
3018
3019 if (mincore((address)stack_extent, os::vm_page_size(), vec) == -1) {
3020 // Fallback to slow path on all errors, including EAGAIN
3021 stack_extent = (uintptr_t) get_stack_commited_bottom(
3022 os::Linux::initial_thread_stack_bottom(),
3023 (size_t)addr - stack_extent);
3024 }
3025
3026 if (stack_extent < (uintptr_t)addr) {
3027 ::munmap((void*)stack_extent, (uintptr_t)(addr - stack_extent));
3028 }
3029 }
3030
3031 return os::commit_memory(addr, size, !ExecMem);
3032 }
3033
3034 // If this is a growable mapping, remove the guard pages entirely by
3035 // munmap()ping them. If not, just call uncommit_memory(). This only
3036 // affects the main/initial thread, but guard against future OS changes
3037 // It's safe to always unmap guard pages for initial thread because we
3038 // always place it right after end of the mapped region
3039
3040 bool os::remove_stack_guard_pages(char* addr, size_t size) {
3041 uintptr_t stack_extent, stack_base;
3042
3043 if (os::Linux::is_initial_thread()) {
3044 return ::munmap(addr, size) == 0;
3045 }
3046
3047 return os::uncommit_memory(addr, size);
3048 }
3049
3050 static address _highest_vm_reserved_address = NULL;
3051
3052 // If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory
3053 // at 'requested_addr'. If there are existing memory mappings at the same
3054 // location, however, they will be overwritten. If 'fixed' is false,
3055 // 'requested_addr' is only treated as a hint, the return value may or
3056 // may not start from the requested address. Unlike Linux mmap(), this
3057 // function returns NULL to indicate failure.
3058 static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) {
3059 char * addr;
3060 int flags;
3061
3062 flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS;
3063 if (fixed) {
3064 assert((uintptr_t)requested_addr % os::Linux::page_size() == 0, "unaligned address");
3065 flags |= MAP_FIXED;
3066 }
3067
3068 // Map reserved/uncommitted pages PROT_NONE so we fail early if we
3069 // touch an uncommitted page. Otherwise, the read/write might
3070 // succeed if we have enough swap space to back the physical page.
3071 addr = (char*)::mmap(requested_addr, bytes, PROT_NONE,
3072 flags, -1, 0);
3073
3074 if (addr != MAP_FAILED) {
3075 // anon_mmap() should only get called during VM initialization,
3076 // don't need lock (actually we can skip locking even it can be called
3077 // from multiple threads, because _highest_vm_reserved_address is just a
3078 // hint about the upper limit of non-stack memory regions.)
3079 if ((address)addr + bytes > _highest_vm_reserved_address) {
3080 _highest_vm_reserved_address = (address)addr + bytes;
3081 }
3082 }
3083
3084 return addr == MAP_FAILED ? NULL : addr;
3085 }
3086
3087 // Don't update _highest_vm_reserved_address, because there might be memory
3088 // regions above addr + size. If so, releasing a memory region only creates
3089 // a hole in the address space, it doesn't help prevent heap-stack collision.
3090 //
3091 static int anon_munmap(char * addr, size_t size) {
3092 return ::munmap(addr, size) == 0;
3093 }
3094
3095 char* os::pd_reserve_memory(size_t bytes, char* requested_addr,
3096 size_t alignment_hint) {
3097 return anon_mmap(requested_addr, bytes, (requested_addr != NULL));
3098 }
3099
3100 bool os::pd_release_memory(char* addr, size_t size) {
3101 return anon_munmap(addr, size);
3102 }
3103
3104 static address highest_vm_reserved_address() {
3105 return _highest_vm_reserved_address;
3106 }
3107
3108 static bool linux_mprotect(char* addr, size_t size, int prot) {
3109 // Linux wants the mprotect address argument to be page aligned.
3110 char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::page_size());
3111
3112 // According to SUSv3, mprotect() should only be used with mappings
3113 // established by mmap(), and mmap() always maps whole pages. Unaligned
3114 // 'addr' likely indicates problem in the VM (e.g. trying to change
3115 // protection of malloc'ed or statically allocated memory). Check the
3116 // caller if you hit this assert.
3117 assert(addr == bottom, "sanity check");
3118
3119 size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Linux::page_size());
3120 return ::mprotect(bottom, size, prot) == 0;
3121 }
3122
3123 // Set protections specified
3124 bool os::protect_memory(char* addr, size_t bytes, ProtType prot,
3125 bool is_committed) {
3126 unsigned int p = 0;
3127 switch (prot) {
3128 case MEM_PROT_NONE: p = PROT_NONE; break;
3129 case MEM_PROT_READ: p = PROT_READ; break;
3130 case MEM_PROT_RW: p = PROT_READ|PROT_WRITE; break;
3131 case MEM_PROT_RWX: p = PROT_READ|PROT_WRITE|PROT_EXEC; break;
3132 default:
3133 ShouldNotReachHere();
3134 }
3135 // is_committed is unused.
3136 return linux_mprotect(addr, bytes, p);
3137 }
3138
3139 bool os::guard_memory(char* addr, size_t size) {
3140 return linux_mprotect(addr, size, PROT_NONE);
3141 }
3142
3143 bool os::unguard_memory(char* addr, size_t size) {
3144 return linux_mprotect(addr, size, PROT_READ|PROT_WRITE);
3145 }
3146
3147 bool os::Linux::transparent_huge_pages_sanity_check(bool warn,
3148 size_t page_size) {
3149 bool result = false;
3150 void *p = mmap(NULL, page_size * 2, PROT_READ|PROT_WRITE,
3151 MAP_ANONYMOUS|MAP_PRIVATE,
3152 -1, 0);
3153 if (p != MAP_FAILED) {
3154 void *aligned_p = align_ptr_up(p, page_size);
3155
3156 result = madvise(aligned_p, page_size, MADV_HUGEPAGE) == 0;
3157
3158 munmap(p, page_size * 2);
3159 }
3160
3161 if (warn && !result) {
3162 warning("TransparentHugePages is not supported by the operating system.");
3163 }
3164
3165 return result;
3166 }
3167
3168 bool os::Linux::hugetlbfs_sanity_check(bool warn, size_t page_size) {
3169 bool result = false;
3170 void *p = mmap(NULL, page_size, PROT_READ|PROT_WRITE,
3171 MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB,
3172 -1, 0);
3173
3174 if (p != MAP_FAILED) {
3175 // We don't know if this really is a huge page or not.
3176 FILE *fp = fopen("/proc/self/maps", "r");
3177 if (fp) {
3178 while (!feof(fp)) {
3179 char chars[257];
3180 long x = 0;
3181 if (fgets(chars, sizeof(chars), fp)) {
3182 if (sscanf(chars, "%lx-%*x", &x) == 1
3183 && x == (long)p) {
3184 if (strstr (chars, "hugepage")) {
3185 result = true;
3186 break;
3187 }
3188 }
3189 }
3190 }
3191 fclose(fp);
3192 }
3193 munmap(p, page_size);
3194 }
3195
3196 if (warn && !result) {
3197 warning("HugeTLBFS is not supported by the operating system.");
3198 }
3199
3200 return result;
3201 }
3202
3203 // Set the coredump_filter bits to include largepages in core dump (bit 6)
3204 //
3205 // From the coredump_filter documentation:
3206 //
3207 // - (bit 0) anonymous private memory
3208 // - (bit 1) anonymous shared memory
3209 // - (bit 2) file-backed private memory
3210 // - (bit 3) file-backed shared memory
3211 // - (bit 4) ELF header pages in file-backed private memory areas (it is
3212 // effective only if the bit 2 is cleared)
3213 // - (bit 5) hugetlb private memory
3214 // - (bit 6) hugetlb shared memory
3215 //
3216 static void set_coredump_filter(void) {
3217 FILE *f;
3218 long cdm;
3219
3220 if ((f = fopen("/proc/self/coredump_filter", "r+")) == NULL) {
3221 return;
3222 }
3223
3224 if (fscanf(f, "%lx", &cdm) != 1) {
3225 fclose(f);
3226 return;
3227 }
3228
3229 rewind(f);
3230
3231 if ((cdm & LARGEPAGES_BIT) == 0) {
3232 cdm |= LARGEPAGES_BIT;
3233 fprintf(f, "%#lx", cdm);
3234 }
3235
3236 fclose(f);
3237 }
3238
3239 // Large page support
3240
3241 static size_t _large_page_size = 0;
3242
3243 size_t os::Linux::find_large_page_size() {
3244 size_t large_page_size = 0;
3245
3246 // large_page_size on Linux is used to round up heap size. x86 uses either
3247 // 2M or 4M page, depending on whether PAE (Physical Address Extensions)
3248 // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use
3249 // page as large as 256M.
3250 //
3251 // Here we try to figure out page size by parsing /proc/meminfo and looking
3252 // for a line with the following format:
3253 // Hugepagesize: 2048 kB
3254 //
3255 // If we can't determine the value (e.g. /proc is not mounted, or the text
3256 // format has been changed), we'll use the largest page size supported by
3257 // the processor.
3258
3259 #ifndef ZERO
3260 large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M)
3261 ARM32_ONLY(2 * M) PPC_ONLY(4 * M) AARCH64_ONLY(2 * M);
3262 #endif // ZERO
3263
3264 FILE *fp = fopen("/proc/meminfo", "r");
3265 if (fp) {
3266 while (!feof(fp)) {
3267 int x = 0;
3268 char buf[16];
3269 if (fscanf(fp, "Hugepagesize: %d", &x) == 1) {
3270 if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) {
3271 large_page_size = x * K;
3272 break;
3273 }
3274 } else {
3275 // skip to next line
3276 for (;;) {
3277 int ch = fgetc(fp);
3278 if (ch == EOF || ch == (int)'\n') break;
3279 }
3280 }
3281 }
3282 fclose(fp);
3283 }
3284
3285 if (!FLAG_IS_DEFAULT(LargePageSizeInBytes) && LargePageSizeInBytes != large_page_size) {
3286 warning("Setting LargePageSizeInBytes has no effect on this OS. Large page size is "
3287 SIZE_FORMAT "%s.", byte_size_in_proper_unit(large_page_size),
3288 proper_unit_for_byte_size(large_page_size));
3289 }
3290
3291 return large_page_size;
3292 }
3293
3294 size_t os::Linux::setup_large_page_size() {
3295 _large_page_size = Linux::find_large_page_size();
3296 const size_t default_page_size = (size_t)Linux::page_size();
3297 if (_large_page_size > default_page_size) {
3298 _page_sizes[0] = _large_page_size;
3299 _page_sizes[1] = default_page_size;
3300 _page_sizes[2] = 0;
3301 }
3302
3303 return _large_page_size;
3304 }
3305
3306 bool os::Linux::setup_large_page_type(size_t page_size) {
3307 if (FLAG_IS_DEFAULT(UseHugeTLBFS) &&
3308 FLAG_IS_DEFAULT(UseSHM) &&
3309 FLAG_IS_DEFAULT(UseTransparentHugePages)) {
3310
3311 // The type of large pages has not been specified by the user.
3312
3313 // Try UseHugeTLBFS and then UseSHM.
3314 UseHugeTLBFS = UseSHM = true;
3315
3316 // Don't try UseTransparentHugePages since there are known
3317 // performance issues with it turned on. This might change in the future.
3318 UseTransparentHugePages = false;
3319 }
3320
3321 if (UseTransparentHugePages) {
3322 bool warn_on_failure = !FLAG_IS_DEFAULT(UseTransparentHugePages);
3323 if (transparent_huge_pages_sanity_check(warn_on_failure, page_size)) {
3324 UseHugeTLBFS = false;
3325 UseSHM = false;
3326 return true;
3327 }
3328 UseTransparentHugePages = false;
3329 }
3330
3331 if (UseHugeTLBFS) {
3332 bool warn_on_failure = !FLAG_IS_DEFAULT(UseHugeTLBFS);
3333 if (hugetlbfs_sanity_check(warn_on_failure, page_size)) {
3334 UseSHM = false;
3335 return true;
3336 }
3337 UseHugeTLBFS = false;
3338 }
3339
3340 return UseSHM;
3341 }
3342
3343 void os::large_page_init() {
3344 if (!UseLargePages &&
3345 !UseTransparentHugePages &&
3346 !UseHugeTLBFS &&
3347 !UseSHM) {
3348 // Not using large pages.
3349 return;
3350 }
3351
3352 if (!FLAG_IS_DEFAULT(UseLargePages) && !UseLargePages) {
3353 // The user explicitly turned off large pages.
3354 // Ignore the rest of the large pages flags.
3355 UseTransparentHugePages = false;
3356 UseHugeTLBFS = false;
3357 UseSHM = false;
3358 return;
3359 }
3360
3361 size_t large_page_size = Linux::setup_large_page_size();
3362 UseLargePages = Linux::setup_large_page_type(large_page_size);
3363
3364 set_coredump_filter();
3365 }
3366
3367 #ifndef SHM_HUGETLB
3368 #define SHM_HUGETLB 04000
3369 #endif
3370
3371 char* os::Linux::reserve_memory_special_shm(size_t bytes, size_t alignment,
3372 char* req_addr, bool exec) {
3373 // "exec" is passed in but not used. Creating the shared image for
3374 // the code cache doesn't have an SHM_X executable permission to check.
3375 assert(UseLargePages && UseSHM, "only for SHM large pages");
3376 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address");
3377
3378 if (!is_size_aligned(bytes, os::large_page_size()) || alignment > os::large_page_size()) {
3379 return NULL; // Fallback to small pages.
3380 }
3381
3382 key_t key = IPC_PRIVATE;
3383 char *addr;
3384
3385 bool warn_on_failure = UseLargePages &&
3386 (!FLAG_IS_DEFAULT(UseLargePages) ||
3387 !FLAG_IS_DEFAULT(UseSHM) ||
3388 !FLAG_IS_DEFAULT(LargePageSizeInBytes));
3389 char msg[128];
3390
3391 // Create a large shared memory region to attach to based on size.
3392 // Currently, size is the total size of the heap
3393 int shmid = shmget(key, bytes, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W);
3394 if (shmid == -1) {
3395 // Possible reasons for shmget failure:
3396 // 1. shmmax is too small for Java heap.
3397 // > check shmmax value: cat /proc/sys/kernel/shmmax
3398 // > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax
3399 // 2. not enough large page memory.
3400 // > check available large pages: cat /proc/meminfo
3401 // > increase amount of large pages:
3402 // echo new_value > /proc/sys/vm/nr_hugepages
3403 // Note 1: different Linux may use different name for this property,
3404 // e.g. on Redhat AS-3 it is "hugetlb_pool".
3405 // Note 2: it's possible there's enough physical memory available but
3406 // they are so fragmented after a long run that they can't
3407 // coalesce into large pages. Try to reserve large pages when
3408 // the system is still "fresh".
3409 if (warn_on_failure) {
3410 jio_snprintf(msg, sizeof(msg), "Failed to reserve shared memory (errno = %d).", errno);
3411 warning("%s", msg);
3412 }
3413 return NULL;
3414 }
3415
3416 // attach to the region
3417 addr = (char*)shmat(shmid, req_addr, 0);
3418 int err = errno;
3419
3420 // Remove shmid. If shmat() is successful, the actual shared memory segment
3421 // will be deleted when it's detached by shmdt() or when the process
3422 // terminates. If shmat() is not successful this will remove the shared
3423 // segment immediately.
3424 shmctl(shmid, IPC_RMID, NULL);
3425
3426 if ((intptr_t)addr == -1) {
3427 if (warn_on_failure) {
3428 jio_snprintf(msg, sizeof(msg), "Failed to attach shared memory (errno = %d).", err);
3429 warning("%s", msg);
3430 }
3431 return NULL;
3432 }
3433
3434 return addr;
3435 }
3436
3437 static void warn_on_large_pages_failure(char* req_addr, size_t bytes,
3438 int error) {
3439 assert(error == ENOMEM, "Only expect to fail if no memory is available");
3440
3441 bool warn_on_failure = UseLargePages &&
3442 (!FLAG_IS_DEFAULT(UseLargePages) ||
3443 !FLAG_IS_DEFAULT(UseHugeTLBFS) ||
3444 !FLAG_IS_DEFAULT(LargePageSizeInBytes));
3445
3446 if (warn_on_failure) {
3447 char msg[128];
3448 jio_snprintf(msg, sizeof(msg), "Failed to reserve large pages memory req_addr: "
3449 PTR_FORMAT " bytes: " SIZE_FORMAT " (errno = %d).", req_addr, bytes, error);
3450 warning("%s", msg);
3451 }
3452 }
3453
3454 char* os::Linux::reserve_memory_special_huge_tlbfs_only(size_t bytes,
3455 char* req_addr,
3456 bool exec) {
3457 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages");
3458 assert(is_size_aligned(bytes, os::large_page_size()), "Unaligned size");
3459 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address");
3460
3461 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
3462 char* addr = (char*)::mmap(req_addr, bytes, prot,
3463 MAP_PRIVATE|MAP_ANONYMOUS|MAP_HUGETLB,
3464 -1, 0);
3465
3466 if (addr == MAP_FAILED) {
3467 warn_on_large_pages_failure(req_addr, bytes, errno);
3468 return NULL;
3469 }
3470
3471 assert(is_ptr_aligned(addr, os::large_page_size()), "Must be");
3472
3473 return addr;
3474 }
3475
3476 char* os::Linux::reserve_memory_special_huge_tlbfs_mixed(size_t bytes,
3477 size_t alignment,
3478 char* req_addr,
3479 bool exec) {
3480 size_t large_page_size = os::large_page_size();
3481
3482 assert(bytes >= large_page_size, "Shouldn't allocate large pages for small sizes");
3483
3484 // Allocate small pages.
3485
3486 char* start;
3487 if (req_addr != NULL) {
3488 assert(is_ptr_aligned(req_addr, alignment), "Must be");
3489 assert(is_size_aligned(bytes, alignment), "Must be");
3490 start = os::reserve_memory(bytes, req_addr);
3491 assert(start == NULL || start == req_addr, "Must be");
3492 } else {
3493 start = os::reserve_memory_aligned(bytes, alignment);
3494 }
3495
3496 if (start == NULL) {
3497 return NULL;
3498 }
3499
3500 assert(is_ptr_aligned(start, alignment), "Must be");
3501
3502 if (MemTracker::tracking_level() > NMT_minimal) {
3503 // os::reserve_memory_special will record this memory area.
3504 // Need to release it here to prevent overlapping reservations.
3505 Tracker tkr = MemTracker::get_virtual_memory_release_tracker();
3506 tkr.record((address)start, bytes);
3507 }
3508
3509 char* end = start + bytes;
3510
3511 // Find the regions of the allocated chunk that can be promoted to large pages.
3512 char* lp_start = (char*)align_ptr_up(start, large_page_size);
3513 char* lp_end = (char*)align_ptr_down(end, large_page_size);
3514
3515 size_t lp_bytes = lp_end - lp_start;
3516
3517 assert(is_size_aligned(lp_bytes, large_page_size), "Must be");
3518
3519 if (lp_bytes == 0) {
3520 // The mapped region doesn't even span the start and the end of a large page.
3521 // Fall back to allocate a non-special area.
3522 ::munmap(start, end - start);
3523 return NULL;
3524 }
3525
3526 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
3527
3528
3529 void* result;
3530
3531 if (start != lp_start) {
3532 result = ::mmap(start, lp_start - start, prot,
3533 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED,
3534 -1, 0);
3535 if (result == MAP_FAILED) {
3536 ::munmap(lp_start, end - lp_start);
3537 return NULL;
3538 }
3539 }
3540
3541 result = ::mmap(lp_start, lp_bytes, prot,
3542 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED|MAP_HUGETLB,
3543 -1, 0);
3544 if (result == MAP_FAILED) {
3545 warn_on_large_pages_failure(req_addr, bytes, errno);
3546 // If the mmap above fails, the large pages region will be unmapped and we
3547 // have regions before and after with small pages. Release these regions.
3548 //
3549 // | mapped | unmapped | mapped |
3550 // ^ ^ ^ ^
3551 // start lp_start lp_end end
3552 //
3553 ::munmap(start, lp_start - start);
3554 ::munmap(lp_end, end - lp_end);
3555 return NULL;
3556 }
3557
3558 if (lp_end != end) {
3559 result = ::mmap(lp_end, end - lp_end, prot,
3560 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED,
3561 -1, 0);
3562 if (result == MAP_FAILED) {
3563 ::munmap(start, lp_end - start);
3564 return NULL;
3565 }
3566 }
3567
3568 return start;
3569 }
3570
3571 char* os::Linux::reserve_memory_special_huge_tlbfs(size_t bytes,
3572 size_t alignment,
3573 char* req_addr,
3574 bool exec) {
3575 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages");
3576 assert(is_ptr_aligned(req_addr, alignment), "Must be");
3577 assert(is_power_of_2(alignment), "Must be");
3578 assert(is_power_of_2(os::large_page_size()), "Must be");
3579 assert(bytes >= os::large_page_size(), "Shouldn't allocate large pages for small sizes");
3580
3581 if (is_size_aligned(bytes, os::large_page_size()) && alignment <= os::large_page_size()) {
3582 return reserve_memory_special_huge_tlbfs_only(bytes, req_addr, exec);
3583 } else {
3584 return reserve_memory_special_huge_tlbfs_mixed(bytes, alignment, req_addr, exec);
3585 }
3586 }
3587
3588 char* os::reserve_memory_special(size_t bytes, size_t alignment,
3589 char* req_addr, bool exec) {
3590 assert(UseLargePages, "only for large pages");
3591
3592 char* addr;
3593 if (UseSHM) {
3594 addr = os::Linux::reserve_memory_special_shm(bytes, alignment, req_addr, exec);
3595 } else {
3596 assert(UseHugeTLBFS, "must be");
3597 addr = os::Linux::reserve_memory_special_huge_tlbfs(bytes, alignment, req_addr, exec);
3598 }
3599
3600 if (addr != NULL) {
3601 if (UseNUMAInterleaving) {
3602 numa_make_global(addr, bytes);
3603 }
3604
3605 // The memory is committed
3606 MemTracker::record_virtual_memory_reserve_and_commit((address)addr, bytes, CALLER_PC);
3607 }
3608
3609 return addr;
3610 }
3611
3612 bool os::Linux::release_memory_special_shm(char* base, size_t bytes) {
3613 // detaching the SHM segment will also delete it, see reserve_memory_special_shm()
3614 return shmdt(base) == 0;
3615 }
3616
3617 bool os::Linux::release_memory_special_huge_tlbfs(char* base, size_t bytes) {
3618 return pd_release_memory(base, bytes);
3619 }
3620
3621 bool os::release_memory_special(char* base, size_t bytes) {
3622 bool res;
3623 if (MemTracker::tracking_level() > NMT_minimal) {
3624 Tracker tkr = MemTracker::get_virtual_memory_release_tracker();
3625 res = os::Linux::release_memory_special_impl(base, bytes);
3626 if (res) {
3627 tkr.record((address)base, bytes);
3628 }
3629
3630 } else {
3631 res = os::Linux::release_memory_special_impl(base, bytes);
3632 }
3633 return res;
3634 }
3635
3636 bool os::Linux::release_memory_special_impl(char* base, size_t bytes) {
3637 assert(UseLargePages, "only for large pages");
3638 bool res;
3639
3640 if (UseSHM) {
3641 res = os::Linux::release_memory_special_shm(base, bytes);
3642 } else {
3643 assert(UseHugeTLBFS, "must be");
3644 res = os::Linux::release_memory_special_huge_tlbfs(base, bytes);
3645 }
3646 return res;
3647 }
3648
3649 size_t os::large_page_size() {
3650 return _large_page_size;
3651 }
3652
3653 // With SysV SHM the entire memory region must be allocated as shared
3654 // memory.
3655 // HugeTLBFS allows application to commit large page memory on demand.
3656 // However, when committing memory with HugeTLBFS fails, the region
3657 // that was supposed to be committed will lose the old reservation
3658 // and allow other threads to steal that memory region. Because of this
3659 // behavior we can't commit HugeTLBFS memory.
3660 bool os::can_commit_large_page_memory() {
3661 return UseTransparentHugePages;
3662 }
3663
3664 bool os::can_execute_large_page_memory() {
3665 return UseTransparentHugePages || UseHugeTLBFS;
3666 }
3667
3668 // Reserve memory at an arbitrary address, only if that area is
3669 // available (and not reserved for something else).
3670
3671 char* os::pd_attempt_reserve_memory_at(size_t bytes, char* requested_addr) {
3672 const int max_tries = 10;
3673 char* base[max_tries];
3674 size_t size[max_tries];
3675 const size_t gap = 0x000000;
3676
3677 // Assert only that the size is a multiple of the page size, since
3678 // that's all that mmap requires, and since that's all we really know
3679 // about at this low abstraction level. If we need higher alignment,
3680 // we can either pass an alignment to this method or verify alignment
3681 // in one of the methods further up the call chain. See bug 5044738.
3682 assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block");
3683
3684 // Repeatedly allocate blocks until the block is allocated at the
3685 // right spot. Give up after max_tries. Note that reserve_memory() will
3686 // automatically update _highest_vm_reserved_address if the call is
3687 // successful. The variable tracks the highest memory address every reserved
3688 // by JVM. It is used to detect heap-stack collision if running with
3689 // fixed-stack LinuxThreads. Because here we may attempt to reserve more
3690 // space than needed, it could confuse the collision detecting code. To
3691 // solve the problem, save current _highest_vm_reserved_address and
3692 // calculate the correct value before return.
3693 address old_highest = _highest_vm_reserved_address;
3694
3695 // Linux mmap allows caller to pass an address as hint; give it a try first,
3696 // if kernel honors the hint then we can return immediately.
3697 char * addr = anon_mmap(requested_addr, bytes, false);
3698 if (addr == requested_addr) {
3699 return requested_addr;
3700 }
3701
3702 if (addr != NULL) {
3703 // mmap() is successful but it fails to reserve at the requested address
3704 anon_munmap(addr, bytes);
3705 }
3706
3707 int i;
3708 for (i = 0; i < max_tries; ++i) {
3709 base[i] = reserve_memory(bytes);
3710
3711 if (base[i] != NULL) {
3712 // Is this the block we wanted?
3713 if (base[i] == requested_addr) {
3714 size[i] = bytes;
3715 break;
3716 }
3717
3718 // Does this overlap the block we wanted? Give back the overlapped
3719 // parts and try again.
3720
3721 ptrdiff_t top_overlap = requested_addr + (bytes + gap) - base[i];
3722 if (top_overlap >= 0 && (size_t)top_overlap < bytes) {
3723 unmap_memory(base[i], top_overlap);
3724 base[i] += top_overlap;
3725 size[i] = bytes - top_overlap;
3726 } else {
3727 ptrdiff_t bottom_overlap = base[i] + bytes - requested_addr;
3728 if (bottom_overlap >= 0 && (size_t)bottom_overlap < bytes) {
3729 unmap_memory(requested_addr, bottom_overlap);
3730 size[i] = bytes - bottom_overlap;
3731 } else {
3732 size[i] = bytes;
3733 }
3734 }
3735 }
3736 }
3737
3738 // Give back the unused reserved pieces.
3739
3740 for (int j = 0; j < i; ++j) {
3741 if (base[j] != NULL) {
3742 unmap_memory(base[j], size[j]);
3743 }
3744 }
3745
3746 if (i < max_tries) {
3747 _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes);
3748 return requested_addr;
3749 } else {
3750 _highest_vm_reserved_address = old_highest;
3751 return NULL;
3752 }
3753 }
3754
3755 size_t os::read(int fd, void *buf, unsigned int nBytes) {
3756 return ::read(fd, buf, nBytes);
3757 }
3758
3759 size_t os::read_at(int fd, void *buf, unsigned int nBytes, jlong offset) {
3760 return ::pread(fd, buf, nBytes, offset);
3761 }
3762
3763 // Short sleep, direct OS call.
3764 //
3765 // Note: certain versions of Linux CFS scheduler (since 2.6.23) do not guarantee
3766 // sched_yield(2) will actually give up the CPU:
3767 //
3768 // * Alone on this pariticular CPU, keeps running.
3769 // * Before the introduction of "skip_buddy" with "compat_yield" disabled
3770 // (pre 2.6.39).
3771 //
3772 // So calling this with 0 is an alternative.
3773 //
3774 void os::naked_short_sleep(jlong ms) {
3775 struct timespec req;
3776
3777 assert(ms < 1000, "Un-interruptable sleep, short time use only");
3778 req.tv_sec = 0;
3779 if (ms > 0) {
3780 req.tv_nsec = (ms % 1000) * 1000000;
3781 } else {
3782 req.tv_nsec = 1;
3783 }
3784
3785 nanosleep(&req, NULL);
3786
3787 return;
3788 }
3789
3790 // Sleep forever; naked call to OS-specific sleep; use with CAUTION
3791 void os::infinite_sleep() {
3792 while (true) { // sleep forever ...
3793 ::sleep(100); // ... 100 seconds at a time
3794 }
3795 }
3796
3797 // Used to convert frequent JVM_Yield() to nops
3798 bool os::dont_yield() {
3799 return DontYieldALot;
3800 }
3801
3802 void os::naked_yield() {
3803 sched_yield();
3804 }
3805
3806 ////////////////////////////////////////////////////////////////////////////////
3807 // thread priority support
3808
3809 // Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER
3810 // only supports dynamic priority, static priority must be zero. For real-time
3811 // applications, Linux supports SCHED_RR which allows static priority (1-99).
3812 // However, for large multi-threaded applications, SCHED_RR is not only slower
3813 // than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out
3814 // of 5 runs - Sep 2005).
3815 //
3816 // The following code actually changes the niceness of kernel-thread/LWP. It
3817 // has an assumption that setpriority() only modifies one kernel-thread/LWP,
3818 // not the entire user process, and user level threads are 1:1 mapped to kernel
3819 // threads. It has always been the case, but could change in the future. For
3820 // this reason, the code should not be used as default (ThreadPriorityPolicy=0).
3821 // It is only used when ThreadPriorityPolicy=1 and requires root privilege.
3822
3823 int os::java_to_os_priority[CriticalPriority + 1] = {
3824 19, // 0 Entry should never be used
3825
3826 4, // 1 MinPriority
3827 3, // 2
3828 2, // 3
3829
3830 1, // 4
3831 0, // 5 NormPriority
3832 -1, // 6
3833
3834 -2, // 7
3835 -3, // 8
3836 -4, // 9 NearMaxPriority
3837
3838 -5, // 10 MaxPriority
3839
3840 -5 // 11 CriticalPriority
3841 };
3842
3843 static int prio_init() {
3844 if (ThreadPriorityPolicy == 1) {
3845 // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1
3846 // if effective uid is not root. Perhaps, a more elegant way of doing
3847 // this is to test CAP_SYS_NICE capability, but that will require libcap.so
3848 if (geteuid() != 0) {
3849 if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) {
3850 warning("-XX:ThreadPriorityPolicy requires root privilege on Linux");
3851 }
3852 ThreadPriorityPolicy = 0;
3853 }
3854 }
3855 if (UseCriticalJavaThreadPriority) {
3856 os::java_to_os_priority[MaxPriority] = os::java_to_os_priority[CriticalPriority];
3857 }
3858 return 0;
3859 }
3860
3861 OSReturn os::set_native_priority(Thread* thread, int newpri) {
3862 if (!UseThreadPriorities || ThreadPriorityPolicy == 0) return OS_OK;
3863
3864 int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri);
3865 return (ret == 0) ? OS_OK : OS_ERR;
3866 }
3867
3868 OSReturn os::get_native_priority(const Thread* const thread,
3869 int *priority_ptr) {
3870 if (!UseThreadPriorities || ThreadPriorityPolicy == 0) {
3871 *priority_ptr = java_to_os_priority[NormPriority];
3872 return OS_OK;
3873 }
3874
3875 errno = 0;
3876 *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id());
3877 return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR);
3878 }
3879
3880 // Hint to the underlying OS that a task switch would not be good.
3881 // Void return because it's a hint and can fail.
3882 void os::hint_no_preempt() {}
3883
3884 ////////////////////////////////////////////////////////////////////////////////
3885 // suspend/resume support
3886
3887 // the low-level signal-based suspend/resume support is a remnant from the
3888 // old VM-suspension that used to be for java-suspension, safepoints etc,
3889 // within hotspot. Now there is a single use-case for this:
3890 // - calling get_thread_pc() on the VMThread by the flat-profiler task
3891 // that runs in the watcher thread.
3892 // The remaining code is greatly simplified from the more general suspension
3893 // code that used to be used.
3894 //
3895 // The protocol is quite simple:
3896 // - suspend:
3897 // - sends a signal to the target thread
3898 // - polls the suspend state of the osthread using a yield loop
3899 // - target thread signal handler (SR_handler) sets suspend state
3900 // and blocks in sigsuspend until continued
3901 // - resume:
3902 // - sets target osthread state to continue
3903 // - sends signal to end the sigsuspend loop in the SR_handler
3904 //
3905 // Note that the SR_lock plays no role in this suspend/resume protocol.
3906
3907 static void resume_clear_context(OSThread *osthread) {
3908 osthread->set_ucontext(NULL);
3909 osthread->set_siginfo(NULL);
3910 }
3911
3912 static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo,
3913 ucontext_t* context) {
3914 osthread->set_ucontext(context);
3915 osthread->set_siginfo(siginfo);
3916 }
3917
3918 // Handler function invoked when a thread's execution is suspended or
3919 // resumed. We have to be careful that only async-safe functions are
3920 // called here (Note: most pthread functions are not async safe and
3921 // should be avoided.)
3922 //
3923 // Note: sigwait() is a more natural fit than sigsuspend() from an
3924 // interface point of view, but sigwait() prevents the signal hander
3925 // from being run. libpthread would get very confused by not having
3926 // its signal handlers run and prevents sigwait()'s use with the
3927 // mutex granting granting signal.
3928 //
3929 // Currently only ever called on the VMThread and JavaThreads (PC sampling)
3930 //
3931 static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) {
3932 // Save and restore errno to avoid confusing native code with EINTR
3933 // after sigsuspend.
3934 int old_errno = errno;
3935
3936 Thread* thread = Thread::current();
3937 OSThread* osthread = thread->osthread();
3938 assert(thread->is_VM_thread() || thread->is_Java_thread(), "Must be VMThread or JavaThread");
3939
3940 os::SuspendResume::State current = osthread->sr.state();
3941 if (current == os::SuspendResume::SR_SUSPEND_REQUEST) {
3942 suspend_save_context(osthread, siginfo, context);
3943
3944 // attempt to switch the state, we assume we had a SUSPEND_REQUEST
3945 os::SuspendResume::State state = osthread->sr.suspended();
3946 if (state == os::SuspendResume::SR_SUSPENDED) {
3947 sigset_t suspend_set; // signals for sigsuspend()
3948
3949 // get current set of blocked signals and unblock resume signal
3950 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set);
3951 sigdelset(&suspend_set, SR_signum);
3952
3953 sr_semaphore.signal();
3954 // wait here until we are resumed
3955 while (1) {
3956 sigsuspend(&suspend_set);
3957
3958 os::SuspendResume::State result = osthread->sr.running();
3959 if (result == os::SuspendResume::SR_RUNNING) {
3960 sr_semaphore.signal();
3961 break;
3962 }
3963 }
3964
3965 } else if (state == os::SuspendResume::SR_RUNNING) {
3966 // request was cancelled, continue
3967 } else {
3968 ShouldNotReachHere();
3969 }
3970
3971 resume_clear_context(osthread);
3972 } else if (current == os::SuspendResume::SR_RUNNING) {
3973 // request was cancelled, continue
3974 } else if (current == os::SuspendResume::SR_WAKEUP_REQUEST) {
3975 // ignore
3976 } else {
3977 // ignore
3978 }
3979
3980 errno = old_errno;
3981 }
3982
3983
3984 static int SR_initialize() {
3985 struct sigaction act;
3986 char *s;
3987 // Get signal number to use for suspend/resume
3988 if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) {
3989 int sig = ::strtol(s, 0, 10);
3990 if (sig > 0 || sig < _NSIG) {
3991 SR_signum = sig;
3992 }
3993 }
3994
3995 assert(SR_signum > SIGSEGV && SR_signum > SIGBUS,
3996 "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769");
3997
3998 sigemptyset(&SR_sigset);
3999 sigaddset(&SR_sigset, SR_signum);
4000
4001 // Set up signal handler for suspend/resume
4002 act.sa_flags = SA_RESTART|SA_SIGINFO;
4003 act.sa_handler = (void (*)(int)) SR_handler;
4004
4005 // SR_signum is blocked by default.
4006 // 4528190 - We also need to block pthread restart signal (32 on all
4007 // supported Linux platforms). Note that LinuxThreads need to block
4008 // this signal for all threads to work properly. So we don't have
4009 // to use hard-coded signal number when setting up the mask.
4010 pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask);
4011
4012 if (sigaction(SR_signum, &act, 0) == -1) {
4013 return -1;
4014 }
4015
4016 // Save signal flag
4017 os::Linux::set_our_sigflags(SR_signum, act.sa_flags);
4018 return 0;
4019 }
4020
4021 static int sr_notify(OSThread* osthread) {
4022 int status = pthread_kill(osthread->pthread_id(), SR_signum);
4023 assert_status(status == 0, status, "pthread_kill");
4024 return status;
4025 }
4026
4027 // "Randomly" selected value for how long we want to spin
4028 // before bailing out on suspending a thread, also how often
4029 // we send a signal to a thread we want to resume
4030 static const int RANDOMLY_LARGE_INTEGER = 1000000;
4031 static const int RANDOMLY_LARGE_INTEGER2 = 100;
4032
4033 // returns true on success and false on error - really an error is fatal
4034 // but this seems the normal response to library errors
4035 static bool do_suspend(OSThread* osthread) {
4036 assert(osthread->sr.is_running(), "thread should be running");
4037 assert(!sr_semaphore.trywait(), "semaphore has invalid state");
4038
4039 // mark as suspended and send signal
4040 if (osthread->sr.request_suspend() != os::SuspendResume::SR_SUSPEND_REQUEST) {
4041 // failed to switch, state wasn't running?
4042 ShouldNotReachHere();
4043 return false;
4044 }
4045
4046 if (sr_notify(osthread) != 0) {
4047 ShouldNotReachHere();
4048 }
4049
4050 // managed to send the signal and switch to SUSPEND_REQUEST, now wait for SUSPENDED
4051 while (true) {
4052 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) {
4053 break;
4054 } else {
4055 // timeout
4056 os::SuspendResume::State cancelled = osthread->sr.cancel_suspend();
4057 if (cancelled == os::SuspendResume::SR_RUNNING) {
4058 return false;
4059 } else if (cancelled == os::SuspendResume::SR_SUSPENDED) {
4060 // make sure that we consume the signal on the semaphore as well
4061 sr_semaphore.wait();
4062 break;
4063 } else {
4064 ShouldNotReachHere();
4065 return false;
4066 }
4067 }
4068 }
4069
4070 guarantee(osthread->sr.is_suspended(), "Must be suspended");
4071 return true;
4072 }
4073
4074 static void do_resume(OSThread* osthread) {
4075 assert(osthread->sr.is_suspended(), "thread should be suspended");
4076 assert(!sr_semaphore.trywait(), "invalid semaphore state");
4077
4078 if (osthread->sr.request_wakeup() != os::SuspendResume::SR_WAKEUP_REQUEST) {
4079 // failed to switch to WAKEUP_REQUEST
4080 ShouldNotReachHere();
4081 return;
4082 }
4083
4084 while (true) {
4085 if (sr_notify(osthread) == 0) {
4086 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) {
4087 if (osthread->sr.is_running()) {
4088 return;
4089 }
4090 }
4091 } else {
4092 ShouldNotReachHere();
4093 }
4094 }
4095
4096 guarantee(osthread->sr.is_running(), "Must be running!");
4097 }
4098
4099 ///////////////////////////////////////////////////////////////////////////////////
4100 // signal handling (except suspend/resume)
4101
4102 // This routine may be used by user applications as a "hook" to catch signals.
4103 // The user-defined signal handler must pass unrecognized signals to this
4104 // routine, and if it returns true (non-zero), then the signal handler must
4105 // return immediately. If the flag "abort_if_unrecognized" is true, then this
4106 // routine will never retun false (zero), but instead will execute a VM panic
4107 // routine kill the process.
4108 //
4109 // If this routine returns false, it is OK to call it again. This allows
4110 // the user-defined signal handler to perform checks either before or after
4111 // the VM performs its own checks. Naturally, the user code would be making
4112 // a serious error if it tried to handle an exception (such as a null check
4113 // or breakpoint) that the VM was generating for its own correct operation.
4114 //
4115 // This routine may recognize any of the following kinds of signals:
4116 // SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1.
4117 // It should be consulted by handlers for any of those signals.
4118 //
4119 // The caller of this routine must pass in the three arguments supplied
4120 // to the function referred to in the "sa_sigaction" (not the "sa_handler")
4121 // field of the structure passed to sigaction(). This routine assumes that
4122 // the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART.
4123 //
4124 // Note that the VM will print warnings if it detects conflicting signal
4125 // handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers".
4126 //
4127 extern "C" JNIEXPORT int JVM_handle_linux_signal(int signo,
4128 siginfo_t* siginfo,
4129 void* ucontext,
4130 int abort_if_unrecognized);
4131
4132 void signalHandler(int sig, siginfo_t* info, void* uc) {
4133 assert(info != NULL && uc != NULL, "it must be old kernel");
4134 int orig_errno = errno; // Preserve errno value over signal handler.
4135 JVM_handle_linux_signal(sig, info, uc, true);
4136 errno = orig_errno;
4137 }
4138
4139
4140 // This boolean allows users to forward their own non-matching signals
4141 // to JVM_handle_linux_signal, harmlessly.
4142 bool os::Linux::signal_handlers_are_installed = false;
4143
4144 // For signal-chaining
4145 struct sigaction os::Linux::sigact[MAXSIGNUM];
4146 unsigned int os::Linux::sigs = 0;
4147 bool os::Linux::libjsig_is_loaded = false;
4148 typedef struct sigaction *(*get_signal_t)(int);
4149 get_signal_t os::Linux::get_signal_action = NULL;
4150
4151 struct sigaction* os::Linux::get_chained_signal_action(int sig) {
4152 struct sigaction *actp = NULL;
4153
4154 if (libjsig_is_loaded) {
4155 // Retrieve the old signal handler from libjsig
4156 actp = (*get_signal_action)(sig);
4157 }
4158 if (actp == NULL) {
4159 // Retrieve the preinstalled signal handler from jvm
4160 actp = get_preinstalled_handler(sig);
4161 }
4162
4163 return actp;
4164 }
4165
4166 static bool call_chained_handler(struct sigaction *actp, int sig,
4167 siginfo_t *siginfo, void *context) {
4168 // Call the old signal handler
4169 if (actp->sa_handler == SIG_DFL) {
4170 // It's more reasonable to let jvm treat it as an unexpected exception
4171 // instead of taking the default action.
4172 return false;
4173 } else if (actp->sa_handler != SIG_IGN) {
4174 if ((actp->sa_flags & SA_NODEFER) == 0) {
4175 // automaticlly block the signal
4176 sigaddset(&(actp->sa_mask), sig);
4177 }
4178
4179 sa_handler_t hand;
4180 sa_sigaction_t sa;
4181 bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0;
4182 // retrieve the chained handler
4183 if (siginfo_flag_set) {
4184 sa = actp->sa_sigaction;
4185 } else {
4186 hand = actp->sa_handler;
4187 }
4188
4189 if ((actp->sa_flags & SA_RESETHAND) != 0) {
4190 actp->sa_handler = SIG_DFL;
4191 }
4192
4193 // try to honor the signal mask
4194 sigset_t oset;
4195 pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset);
4196
4197 // call into the chained handler
4198 if (siginfo_flag_set) {
4199 (*sa)(sig, siginfo, context);
4200 } else {
4201 (*hand)(sig);
4202 }
4203
4204 // restore the signal mask
4205 pthread_sigmask(SIG_SETMASK, &oset, 0);
4206 }
4207 // Tell jvm's signal handler the signal is taken care of.
4208 return true;
4209 }
4210
4211 bool os::Linux::chained_handler(int sig, siginfo_t* siginfo, void* context) {
4212 bool chained = false;
4213 // signal-chaining
4214 if (UseSignalChaining) {
4215 struct sigaction *actp = get_chained_signal_action(sig);
4216 if (actp != NULL) {
4217 chained = call_chained_handler(actp, sig, siginfo, context);
4218 }
4219 }
4220 return chained;
4221 }
4222
4223 struct sigaction* os::Linux::get_preinstalled_handler(int sig) {
4224 if ((((unsigned int)1 << sig) & sigs) != 0) {
4225 return &sigact[sig];
4226 }
4227 return NULL;
4228 }
4229
4230 void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) {
4231 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4232 sigact[sig] = oldAct;
4233 sigs |= (unsigned int)1 << sig;
4234 }
4235
4236 // for diagnostic
4237 int os::Linux::sigflags[MAXSIGNUM];
4238
4239 int os::Linux::get_our_sigflags(int sig) {
4240 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4241 return sigflags[sig];
4242 }
4243
4244 void os::Linux::set_our_sigflags(int sig, int flags) {
4245 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4246 sigflags[sig] = flags;
4247 }
4248
4249 void os::Linux::set_signal_handler(int sig, bool set_installed) {
4250 // Check for overwrite.
4251 struct sigaction oldAct;
4252 sigaction(sig, (struct sigaction*)NULL, &oldAct);
4253
4254 void* oldhand = oldAct.sa_sigaction
4255 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction)
4256 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler);
4257 if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) &&
4258 oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) &&
4259 oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) {
4260 if (AllowUserSignalHandlers || !set_installed) {
4261 // Do not overwrite; user takes responsibility to forward to us.
4262 return;
4263 } else if (UseSignalChaining) {
4264 // save the old handler in jvm
4265 save_preinstalled_handler(sig, oldAct);
4266 // libjsig also interposes the sigaction() call below and saves the
4267 // old sigaction on it own.
4268 } else {
4269 fatal(err_msg("Encountered unexpected pre-existing sigaction handler "
4270 "%#lx for signal %d.", (long)oldhand, sig));
4271 }
4272 }
4273
4274 struct sigaction sigAct;
4275 sigfillset(&(sigAct.sa_mask));
4276 sigAct.sa_handler = SIG_DFL;
4277 if (!set_installed) {
4278 sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
4279 } else {
4280 sigAct.sa_sigaction = signalHandler;
4281 sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
4282 }
4283 // Save flags, which are set by ours
4284 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4285 sigflags[sig] = sigAct.sa_flags;
4286
4287 int ret = sigaction(sig, &sigAct, &oldAct);
4288 assert(ret == 0, "check");
4289
4290 void* oldhand2 = oldAct.sa_sigaction
4291 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction)
4292 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler);
4293 assert(oldhand2 == oldhand, "no concurrent signal handler installation");
4294 }
4295
4296 // install signal handlers for signals that HotSpot needs to
4297 // handle in order to support Java-level exception handling.
4298
4299 void os::Linux::install_signal_handlers() {
4300 if (!signal_handlers_are_installed) {
4301 signal_handlers_are_installed = true;
4302
4303 // signal-chaining
4304 typedef void (*signal_setting_t)();
4305 signal_setting_t begin_signal_setting = NULL;
4306 signal_setting_t end_signal_setting = NULL;
4307 begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
4308 dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting"));
4309 if (begin_signal_setting != NULL) {
4310 end_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
4311 dlsym(RTLD_DEFAULT, "JVM_end_signal_setting"));
4312 get_signal_action = CAST_TO_FN_PTR(get_signal_t,
4313 dlsym(RTLD_DEFAULT, "JVM_get_signal_action"));
4314 libjsig_is_loaded = true;
4315 assert(UseSignalChaining, "should enable signal-chaining");
4316 }
4317 if (libjsig_is_loaded) {
4318 // Tell libjsig jvm is setting signal handlers
4319 (*begin_signal_setting)();
4320 }
4321
4322 set_signal_handler(SIGSEGV, true);
4323 set_signal_handler(SIGPIPE, true);
4324 set_signal_handler(SIGBUS, true);
4325 set_signal_handler(SIGILL, true);
4326 set_signal_handler(SIGFPE, true);
4327 #if defined(PPC64)
4328 set_signal_handler(SIGTRAP, true);
4329 #endif
4330 set_signal_handler(SIGXFSZ, true);
4331
4332 if (libjsig_is_loaded) {
4333 // Tell libjsig jvm finishes setting signal handlers
4334 (*end_signal_setting)();
4335 }
4336
4337 // We don't activate signal checker if libjsig is in place, we trust ourselves
4338 // and if UserSignalHandler is installed all bets are off.
4339 // Log that signal checking is off only if -verbose:jni is specified.
4340 if (CheckJNICalls) {
4341 if (libjsig_is_loaded) {
4342 if (PrintJNIResolving) {
4343 tty->print_cr("Info: libjsig is activated, all active signal checking is disabled");
4344 }
4345 check_signals = false;
4346 }
4347 if (AllowUserSignalHandlers) {
4348 if (PrintJNIResolving) {
4349 tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled");
4350 }
4351 check_signals = false;
4352 }
4353 }
4354 }
4355 }
4356
4357 // This is the fastest way to get thread cpu time on Linux.
4358 // Returns cpu time (user+sys) for any thread, not only for current.
4359 // POSIX compliant clocks are implemented in the kernels 2.6.16+.
4360 // It might work on 2.6.10+ with a special kernel/glibc patch.
4361 // For reference, please, see IEEE Std 1003.1-2004:
4362 // http://www.unix.org/single_unix_specification
4363
4364 jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) {
4365 struct timespec tp;
4366 int rc = os::Linux::clock_gettime(clockid, &tp);
4367 assert(rc == 0, "clock_gettime is expected to return 0 code");
4368
4369 return (tp.tv_sec * NANOSECS_PER_SEC) + tp.tv_nsec;
4370 }
4371
4372 /////
4373 // glibc on Linux platform uses non-documented flag
4374 // to indicate, that some special sort of signal
4375 // trampoline is used.
4376 // We will never set this flag, and we should
4377 // ignore this flag in our diagnostic
4378 #ifdef SIGNIFICANT_SIGNAL_MASK
4379 #undef SIGNIFICANT_SIGNAL_MASK
4380 #endif
4381 #define SIGNIFICANT_SIGNAL_MASK (~0x04000000)
4382
4383 static const char* get_signal_handler_name(address handler,
4384 char* buf, int buflen) {
4385 int offset;
4386 bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset);
4387 if (found) {
4388 // skip directory names
4389 const char *p1, *p2;
4390 p1 = buf;
4391 size_t len = strlen(os::file_separator());
4392 while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len;
4393 jio_snprintf(buf, buflen, "%s+0x%x", p1, offset);
4394 } else {
4395 jio_snprintf(buf, buflen, PTR_FORMAT, handler);
4396 }
4397 return buf;
4398 }
4399
4400 static void print_signal_handler(outputStream* st, int sig,
4401 char* buf, size_t buflen) {
4402 struct sigaction sa;
4403
4404 sigaction(sig, NULL, &sa);
4405
4406 // See comment for SIGNIFICANT_SIGNAL_MASK define
4407 sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
4408
4409 st->print("%s: ", os::exception_name(sig, buf, buflen));
4410
4411 address handler = (sa.sa_flags & SA_SIGINFO)
4412 ? CAST_FROM_FN_PTR(address, sa.sa_sigaction)
4413 : CAST_FROM_FN_PTR(address, sa.sa_handler);
4414
4415 if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) {
4416 st->print("SIG_DFL");
4417 } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) {
4418 st->print("SIG_IGN");
4419 } else {
4420 st->print("[%s]", get_signal_handler_name(handler, buf, buflen));
4421 }
4422
4423 st->print(", sa_mask[0]=");
4424 os::Posix::print_signal_set_short(st, &sa.sa_mask);
4425
4426 address rh = VMError::get_resetted_sighandler(sig);
4427 // May be, handler was resetted by VMError?
4428 if (rh != NULL) {
4429 handler = rh;
4430 sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK;
4431 }
4432
4433 st->print(", sa_flags=");
4434 os::Posix::print_sa_flags(st, sa.sa_flags);
4435
4436 // Check: is it our handler?
4437 if (handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) ||
4438 handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) {
4439 // It is our signal handler
4440 // check for flags, reset system-used one!
4441 if ((int)sa.sa_flags != os::Linux::get_our_sigflags(sig)) {
4442 st->print(
4443 ", flags was changed from " PTR32_FORMAT ", consider using jsig library",
4444 os::Linux::get_our_sigflags(sig));
4445 }
4446 }
4447 st->cr();
4448 }
4449
4450
4451 #define DO_SIGNAL_CHECK(sig) \
4452 do { \
4453 if (!sigismember(&check_signal_done, sig)) { \
4454 os::Linux::check_signal_handler(sig); \
4455 } \
4456 } while (0)
4457
4458 // This method is a periodic task to check for misbehaving JNI applications
4459 // under CheckJNI, we can add any periodic checks here
4460
4461 void os::run_periodic_checks() {
4462 if (check_signals == false) return;
4463
4464 // SEGV and BUS if overridden could potentially prevent
4465 // generation of hs*.log in the event of a crash, debugging
4466 // such a case can be very challenging, so we absolutely
4467 // check the following for a good measure:
4468 DO_SIGNAL_CHECK(SIGSEGV);
4469 DO_SIGNAL_CHECK(SIGILL);
4470 DO_SIGNAL_CHECK(SIGFPE);
4471 DO_SIGNAL_CHECK(SIGBUS);
4472 DO_SIGNAL_CHECK(SIGPIPE);
4473 DO_SIGNAL_CHECK(SIGXFSZ);
4474 #if defined(PPC64)
4475 DO_SIGNAL_CHECK(SIGTRAP);
4476 #endif
4477
4478 // ReduceSignalUsage allows the user to override these handlers
4479 // see comments at the very top and jvm_solaris.h
4480 if (!ReduceSignalUsage) {
4481 DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL);
4482 DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL);
4483 DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL);
4484 DO_SIGNAL_CHECK(BREAK_SIGNAL);
4485 }
4486
4487 DO_SIGNAL_CHECK(SR_signum);
4488 DO_SIGNAL_CHECK(INTERRUPT_SIGNAL);
4489 }
4490
4491 typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *);
4492
4493 static os_sigaction_t os_sigaction = NULL;
4494
4495 void os::Linux::check_signal_handler(int sig) {
4496 char buf[O_BUFLEN];
4497 address jvmHandler = NULL;
4498
4499
4500 struct sigaction act;
4501 if (os_sigaction == NULL) {
4502 // only trust the default sigaction, in case it has been interposed
4503 os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction");
4504 if (os_sigaction == NULL) return;
4505 }
4506
4507 os_sigaction(sig, (struct sigaction*)NULL, &act);
4508
4509
4510 act.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
4511
4512 address thisHandler = (act.sa_flags & SA_SIGINFO)
4513 ? CAST_FROM_FN_PTR(address, act.sa_sigaction)
4514 : CAST_FROM_FN_PTR(address, act.sa_handler);
4515
4516
4517 switch (sig) {
4518 case SIGSEGV:
4519 case SIGBUS:
4520 case SIGFPE:
4521 case SIGPIPE:
4522 case SIGILL:
4523 case SIGXFSZ:
4524 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler);
4525 break;
4526
4527 case SHUTDOWN1_SIGNAL:
4528 case SHUTDOWN2_SIGNAL:
4529 case SHUTDOWN3_SIGNAL:
4530 case BREAK_SIGNAL:
4531 jvmHandler = (address)user_handler();
4532 break;
4533
4534 case INTERRUPT_SIGNAL:
4535 jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL);
4536 break;
4537
4538 default:
4539 if (sig == SR_signum) {
4540 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler);
4541 } else {
4542 return;
4543 }
4544 break;
4545 }
4546
4547 if (thisHandler != jvmHandler) {
4548 tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN));
4549 tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN));
4550 tty->print_cr(" found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN));
4551 // No need to check this sig any longer
4552 sigaddset(&check_signal_done, sig);
4553 // Running under non-interactive shell, SHUTDOWN2_SIGNAL will be reassigned SIG_IGN
4554 if (sig == SHUTDOWN2_SIGNAL && !isatty(fileno(stdin))) {
4555 tty->print_cr("Running in non-interactive shell, %s handler is replaced by shell",
4556 exception_name(sig, buf, O_BUFLEN));
4557 }
4558 } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) {
4559 tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN));
4560 tty->print("expected:" PTR32_FORMAT, os::Linux::get_our_sigflags(sig));
4561 tty->print_cr(" found:" PTR32_FORMAT, act.sa_flags);
4562 // No need to check this sig any longer
4563 sigaddset(&check_signal_done, sig);
4564 }
4565
4566 // Dump all the signal
4567 if (sigismember(&check_signal_done, sig)) {
4568 print_signal_handlers(tty, buf, O_BUFLEN);
4569 }
4570 }
4571
4572 extern void report_error(char* file_name, int line_no, char* title,
4573 char* format, ...);
4574
4575 extern bool signal_name(int signo, char* buf, size_t len);
4576
4577 const char* os::exception_name(int exception_code, char* buf, size_t size) {
4578 if (0 < exception_code && exception_code <= SIGRTMAX) {
4579 // signal
4580 if (!signal_name(exception_code, buf, size)) {
4581 jio_snprintf(buf, size, "SIG%d", exception_code);
4582 }
4583 return buf;
4584 } else {
4585 return NULL;
4586 }
4587 }
4588
4589 // this is called _before_ the most of global arguments have been parsed
4590 void os::init(void) {
4591 char dummy; // used to get a guess on initial stack address
4592 // first_hrtime = gethrtime();
4593
4594 // With LinuxThreads the JavaMain thread pid (primordial thread)
4595 // is different than the pid of the java launcher thread.
4596 // So, on Linux, the launcher thread pid is passed to the VM
4597 // via the sun.java.launcher.pid property.
4598 // Use this property instead of getpid() if it was correctly passed.
4599 // See bug 6351349.
4600 pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid();
4601
4602 _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid();
4603
4604 clock_tics_per_sec = sysconf(_SC_CLK_TCK);
4605
4606 init_random(1234567);
4607
4608 ThreadCritical::initialize();
4609
4610 Linux::set_page_size(sysconf(_SC_PAGESIZE));
4611 if (Linux::page_size() == -1) {
4612 fatal(err_msg("os_linux.cpp: os::init: sysconf failed (%s)",
4613 strerror(errno)));
4614 }
4615 init_page_sizes((size_t) Linux::page_size());
4616
4617 Linux::initialize_system_info();
4618
4619 // main_thread points to the aboriginal thread
4620 Linux::_main_thread = pthread_self();
4621
4622 Linux::clock_init();
4623 initial_time_count = javaTimeNanos();
4624
4625 // pthread_condattr initialization for monotonic clock
4626 int status;
4627 pthread_condattr_t* _condattr = os::Linux::condAttr();
4628 if ((status = pthread_condattr_init(_condattr)) != 0) {
4629 fatal(err_msg("pthread_condattr_init: %s", strerror(status)));
4630 }
4631 // Only set the clock if CLOCK_MONOTONIC is available
4632 if (os::supports_monotonic_clock()) {
4633 if ((status = pthread_condattr_setclock(_condattr, CLOCK_MONOTONIC)) != 0) {
4634 if (status == EINVAL) {
4635 warning("Unable to use monotonic clock with relative timed-waits" \
4636 " - changes to the time-of-day clock may have adverse affects");
4637 } else {
4638 fatal(err_msg("pthread_condattr_setclock: %s", strerror(status)));
4639 }
4640 }
4641 }
4642 // else it defaults to CLOCK_REALTIME
4643
4644 pthread_mutex_init(&dl_mutex, NULL);
4645
4646 // If the pagesize of the VM is greater than 8K determine the appropriate
4647 // number of initial guard pages. The user can change this with the
4648 // command line arguments, if needed.
4649 if (vm_page_size() > (int)Linux::vm_default_page_size()) {
4650 StackYellowPages = 1;
4651 StackRedPages = 1;
4652 StackShadowPages = round_to((StackShadowPages*Linux::vm_default_page_size()), vm_page_size()) / vm_page_size();
4653 }
4654
4655 // retrieve entry point for pthread_setname_np
4656 Linux::_pthread_setname_np =
4657 (int(*)(pthread_t, const char*))dlsym(RTLD_DEFAULT, "pthread_setname_np");
4658
4659 }
4660
4661 // To install functions for atexit system call
4662 extern "C" {
4663 static void perfMemory_exit_helper() {
4664 perfMemory_exit();
4665 }
4666 }
4667
4668 // this is called _after_ the global arguments have been parsed
4669 jint os::init_2(void) {
4670 Linux::fast_thread_clock_init();
4671
4672 // Allocate a single page and mark it as readable for safepoint polling
4673 address polling_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
4674 guarantee(polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page");
4675
4676 os::set_polling_page(polling_page);
4677
4678 #ifndef PRODUCT
4679 if (Verbose && PrintMiscellaneous) {
4680 tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n",
4681 (intptr_t)polling_page);
4682 }
4683 #endif
4684
4685 if (!UseMembar) {
4686 address mem_serialize_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
4687 guarantee(mem_serialize_page != MAP_FAILED, "mmap Failed for memory serialize page");
4688 os::set_memory_serialize_page(mem_serialize_page);
4689
4690 #ifndef PRODUCT
4691 if (Verbose && PrintMiscellaneous) {
4692 tty->print("[Memory Serialize Page address: " INTPTR_FORMAT "]\n",
4693 (intptr_t)mem_serialize_page);
4694 }
4695 #endif
4696 }
4697
4698 // initialize suspend/resume support - must do this before signal_sets_init()
4699 if (SR_initialize() != 0) {
4700 perror("SR_initialize failed");
4701 return JNI_ERR;
4702 }
4703
4704 Linux::signal_sets_init();
4705 Linux::install_signal_handlers();
4706
4707 // Check minimum allowable stack size for thread creation and to initialize
4708 // the java system classes, including StackOverflowError - depends on page
4709 // size. Add a page for compiler2 recursion in main thread.
4710 // Add in 2*BytesPerWord times page size to account for VM stack during
4711 // class initialization depending on 32 or 64 bit VM.
4712 os::Linux::min_stack_allowed = MAX2(os::Linux::min_stack_allowed,
4713 (size_t)(StackYellowPages+StackRedPages+StackShadowPages) * Linux::page_size() +
4714 (2*BytesPerWord COMPILER2_PRESENT(+1)) * Linux::vm_default_page_size());
4715
4716 size_t threadStackSizeInBytes = ThreadStackSize * K;
4717 if (threadStackSizeInBytes != 0 &&
4718 threadStackSizeInBytes < os::Linux::min_stack_allowed) {
4719 tty->print_cr("\nThe stack size specified is too small, "
4720 "Specify at least %dk",
4721 os::Linux::min_stack_allowed/ K);
4722 return JNI_ERR;
4723 }
4724
4725 // Make the stack size a multiple of the page size so that
4726 // the yellow/red zones can be guarded.
4727 JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes,
4728 vm_page_size()));
4729
4730 Linux::capture_initial_stack(JavaThread::stack_size_at_create());
4731
4732 #if defined(IA32)
4733 workaround_expand_exec_shield_cs_limit();
4734 #endif
4735
4736 Linux::libpthread_init();
4737 if (PrintMiscellaneous && (Verbose || WizardMode)) {
4738 tty->print_cr("[HotSpot is running with %s, %s(%s)]\n",
4739 Linux::glibc_version(), Linux::libpthread_version(),
4740 Linux::is_floating_stack() ? "floating stack" : "fixed stack");
4741 }
4742
4743 if (UseNUMA) {
4744 if (!Linux::libnuma_init()) {
4745 UseNUMA = false;
4746 } else {
4747 if ((Linux::numa_max_node() < 1)) {
4748 // There's only one node(they start from 0), disable NUMA.
4749 UseNUMA = false;
4750 }
4751 }
4752 // With SHM and HugeTLBFS large pages we cannot uncommit a page, so there's no way
4753 // we can make the adaptive lgrp chunk resizing work. If the user specified
4754 // both UseNUMA and UseLargePages (or UseSHM/UseHugeTLBFS) on the command line - warn and
4755 // disable adaptive resizing.
4756 if (UseNUMA && UseLargePages && !can_commit_large_page_memory()) {
4757 if (FLAG_IS_DEFAULT(UseNUMA)) {
4758 UseNUMA = false;
4759 } else {
4760 if (FLAG_IS_DEFAULT(UseLargePages) &&
4761 FLAG_IS_DEFAULT(UseSHM) &&
4762 FLAG_IS_DEFAULT(UseHugeTLBFS)) {
4763 UseLargePages = false;
4764 } else {
4765 warning("UseNUMA is not fully compatible with SHM/HugeTLBFS large pages, disabling adaptive resizing");
4766 UseAdaptiveSizePolicy = false;
4767 UseAdaptiveNUMAChunkSizing = false;
4768 }
4769 }
4770 }
4771 if (!UseNUMA && ForceNUMA) {
4772 UseNUMA = true;
4773 }
4774 }
4775
4776 if (MaxFDLimit) {
4777 // set the number of file descriptors to max. print out error
4778 // if getrlimit/setrlimit fails but continue regardless.
4779 struct rlimit nbr_files;
4780 int status = getrlimit(RLIMIT_NOFILE, &nbr_files);
4781 if (status != 0) {
4782 if (PrintMiscellaneous && (Verbose || WizardMode)) {
4783 perror("os::init_2 getrlimit failed");
4784 }
4785 } else {
4786 nbr_files.rlim_cur = nbr_files.rlim_max;
4787 status = setrlimit(RLIMIT_NOFILE, &nbr_files);
4788 if (status != 0) {
4789 if (PrintMiscellaneous && (Verbose || WizardMode)) {
4790 perror("os::init_2 setrlimit failed");
4791 }
4792 }
4793 }
4794 }
4795
4796 // Initialize lock used to serialize thread creation (see os::create_thread)
4797 Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false));
4798
4799 // at-exit methods are called in the reverse order of their registration.
4800 // atexit functions are called on return from main or as a result of a
4801 // call to exit(3C). There can be only 32 of these functions registered
4802 // and atexit() does not set errno.
4803
4804 if (PerfAllowAtExitRegistration) {
4805 // only register atexit functions if PerfAllowAtExitRegistration is set.
4806 // atexit functions can be delayed until process exit time, which
4807 // can be problematic for embedded VM situations. Embedded VMs should
4808 // call DestroyJavaVM() to assure that VM resources are released.
4809
4810 // note: perfMemory_exit_helper atexit function may be removed in
4811 // the future if the appropriate cleanup code can be added to the
4812 // VM_Exit VMOperation's doit method.
4813 if (atexit(perfMemory_exit_helper) != 0) {
4814 warning("os::init_2 atexit(perfMemory_exit_helper) failed");
4815 }
4816 }
4817
4818 // initialize thread priority policy
4819 prio_init();
4820
4821 return JNI_OK;
4822 }
4823
4824 // Mark the polling page as unreadable
4825 void os::make_polling_page_unreadable(void) {
4826 if (!guard_memory((char*)_polling_page, Linux::page_size())) {
4827 fatal("Could not disable polling page");
4828 }
4829 }
4830
4831 // Mark the polling page as readable
4832 void os::make_polling_page_readable(void) {
4833 if (!linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) {
4834 fatal("Could not enable polling page");
4835 }
4836 }
4837
4838 int os::active_processor_count() {
4839 // Linux doesn't yet have a (official) notion of processor sets,
4840 // so just return the number of online processors.
4841 int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN);
4842 assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check");
4843 return online_cpus;
4844 }
4845
4846 void os::set_native_thread_name(const char *name) {
4847 if (Linux::_pthread_setname_np) {
4848 char buf [16]; // according to glibc manpage, 16 chars incl. '/0'
4849 snprintf(buf, sizeof(buf), "%s", name);
4850 buf[sizeof(buf) - 1] = '\0';
4851 const int rc = Linux::_pthread_setname_np(pthread_self(), buf);
4852 // ERANGE should not happen; all other errors should just be ignored.
4853 assert(rc != ERANGE, "pthread_setname_np failed");
4854 }
4855 }
4856
4857 bool os::distribute_processes(uint length, uint* distribution) {
4858 // Not yet implemented.
4859 return false;
4860 }
4861
4862 bool os::bind_to_processor(uint processor_id) {
4863 // Not yet implemented.
4864 return false;
4865 }
4866
4867 ///
4868
4869 void os::SuspendedThreadTask::internal_do_task() {
4870 if (do_suspend(_thread->osthread())) {
4871 SuspendedThreadTaskContext context(_thread, _thread->osthread()->ucontext());
4872 do_task(context);
4873 do_resume(_thread->osthread());
4874 }
4875 }
4876
4877 class PcFetcher : public os::SuspendedThreadTask {
4878 public:
4879 PcFetcher(Thread* thread) : os::SuspendedThreadTask(thread) {}
4880 ExtendedPC result();
4881 protected:
4882 void do_task(const os::SuspendedThreadTaskContext& context);
4883 private:
4884 ExtendedPC _epc;
4885 };
4886
4887 ExtendedPC PcFetcher::result() {
4888 guarantee(is_done(), "task is not done yet.");
4889 return _epc;
4890 }
4891
4892 void PcFetcher::do_task(const os::SuspendedThreadTaskContext& context) {
4893 Thread* thread = context.thread();
4894 OSThread* osthread = thread->osthread();
4895 if (osthread->ucontext() != NULL) {
4896 _epc = os::Linux::ucontext_get_pc((ucontext_t *) context.ucontext());
4897 } else {
4898 // NULL context is unexpected, double-check this is the VMThread
4899 guarantee(thread->is_VM_thread(), "can only be called for VMThread");
4900 }
4901 }
4902
4903 // Suspends the target using the signal mechanism and then grabs the PC before
4904 // resuming the target. Used by the flat-profiler only
4905 ExtendedPC os::get_thread_pc(Thread* thread) {
4906 // Make sure that it is called by the watcher for the VMThread
4907 assert(Thread::current()->is_Watcher_thread(), "Must be watcher");
4908 assert(thread->is_VM_thread(), "Can only be called for VMThread");
4909
4910 PcFetcher fetcher(thread);
4911 fetcher.run();
4912 return fetcher.result();
4913 }
4914
4915 int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond,
4916 pthread_mutex_t *_mutex,
4917 const struct timespec *_abstime) {
4918 if (is_NPTL()) {
4919 return pthread_cond_timedwait(_cond, _mutex, _abstime);
4920 } else {
4921 // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control
4922 // word back to default 64bit precision if condvar is signaled. Java
4923 // wants 53bit precision. Save and restore current value.
4924 int fpu = get_fpu_control_word();
4925 int status = pthread_cond_timedwait(_cond, _mutex, _abstime);
4926 set_fpu_control_word(fpu);
4927 return status;
4928 }
4929 }
4930
4931 ////////////////////////////////////////////////////////////////////////////////
4932 // debug support
4933
4934 bool os::find(address addr, outputStream* st) {
4935 Dl_info dlinfo;
4936 memset(&dlinfo, 0, sizeof(dlinfo));
4937 if (dladdr(addr, &dlinfo) != 0) {
4938 st->print(PTR_FORMAT ": ", addr);
4939 if (dlinfo.dli_sname != NULL && dlinfo.dli_saddr != NULL) {
4940 st->print("%s+%#x", dlinfo.dli_sname,
4941 addr - (intptr_t)dlinfo.dli_saddr);
4942 } else if (dlinfo.dli_fbase != NULL) {
4943 st->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase);
4944 } else {
4945 st->print("<absolute address>");
4946 }
4947 if (dlinfo.dli_fname != NULL) {
4948 st->print(" in %s", dlinfo.dli_fname);
4949 }
4950 if (dlinfo.dli_fbase != NULL) {
4951 st->print(" at " PTR_FORMAT, dlinfo.dli_fbase);
4952 }
4953 st->cr();
4954
4955 if (Verbose) {
4956 // decode some bytes around the PC
4957 address begin = clamp_address_in_page(addr-40, addr, os::vm_page_size());
4958 address end = clamp_address_in_page(addr+40, addr, os::vm_page_size());
4959 address lowest = (address) dlinfo.dli_sname;
4960 if (!lowest) lowest = (address) dlinfo.dli_fbase;
4961 if (begin < lowest) begin = lowest;
4962 Dl_info dlinfo2;
4963 if (dladdr(end, &dlinfo2) != 0 && dlinfo2.dli_saddr != dlinfo.dli_saddr
4964 && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin) {
4965 end = (address) dlinfo2.dli_saddr;
4966 }
4967 Disassembler::decode(begin, end, st);
4968 }
4969 return true;
4970 }
4971 return false;
4972 }
4973
4974 ////////////////////////////////////////////////////////////////////////////////
4975 // misc
4976
4977 // This does not do anything on Linux. This is basically a hook for being
4978 // able to use structured exception handling (thread-local exception filters)
4979 // on, e.g., Win32.
4980 void
4981 os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method,
4982 JavaCallArguments* args, Thread* thread) {
4983 f(value, method, args, thread);
4984 }
4985
4986 void os::print_statistics() {
4987 }
4988
4989 int os::message_box(const char* title, const char* message) {
4990 int i;
4991 fdStream err(defaultStream::error_fd());
4992 for (i = 0; i < 78; i++) err.print_raw("=");
4993 err.cr();
4994 err.print_raw_cr(title);
4995 for (i = 0; i < 78; i++) err.print_raw("-");
4996 err.cr();
4997 err.print_raw_cr(message);
4998 for (i = 0; i < 78; i++) err.print_raw("=");
4999 err.cr();
5000
5001 char buf[16];
5002 // Prevent process from exiting upon "read error" without consuming all CPU
5003 while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); }
5004
5005 return buf[0] == 'y' || buf[0] == 'Y';
5006 }
5007
5008 int os::stat(const char *path, struct stat *sbuf) {
5009 char pathbuf[MAX_PATH];
5010 if (strlen(path) > MAX_PATH - 1) {
5011 errno = ENAMETOOLONG;
5012 return -1;
5013 }
5014 os::native_path(strcpy(pathbuf, path));
5015 return ::stat(pathbuf, sbuf);
5016 }
5017
5018 bool os::check_heap(bool force) {
5019 return true;
5020 }
5021
5022 // Is a (classpath) directory empty?
5023 bool os::dir_is_empty(const char* path) {
5024 DIR *dir = NULL;
5025 struct dirent *ptr;
5026
5027 dir = opendir(path);
5028 if (dir == NULL) return true;
5029
5030 // Scan the directory
5031 bool result = true;
5032 char buf[sizeof(struct dirent) + MAX_PATH];
5033 while (result && (ptr = ::readdir(dir)) != NULL) {
5034 if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) {
5035 result = false;
5036 }
5037 }
5038 closedir(dir);
5039 return result;
5040 }
5041
5042 // This code originates from JDK's sysOpen and open64_w
5043 // from src/solaris/hpi/src/system_md.c
5044
5045 int os::open(const char *path, int oflag, int mode) {
5046 if (strlen(path) > MAX_PATH - 1) {
5047 errno = ENAMETOOLONG;
5048 return -1;
5049 }
5050
5051 // All file descriptors that are opened in the Java process and not
5052 // specifically destined for a subprocess should have the close-on-exec
5053 // flag set. If we don't set it, then careless 3rd party native code
5054 // might fork and exec without closing all appropriate file descriptors
5055 // (e.g. as we do in closeDescriptors in UNIXProcess.c), and this in
5056 // turn might:
5057 //
5058 // - cause end-of-file to fail to be detected on some file
5059 // descriptors, resulting in mysterious hangs, or
5060 //
5061 // - might cause an fopen in the subprocess to fail on a system
5062 // suffering from bug 1085341.
5063 //
5064 // (Yes, the default setting of the close-on-exec flag is a Unix
5065 // design flaw)
5066 //
5067 // See:
5068 // 1085341: 32-bit stdio routines should support file descriptors >255
5069 // 4843136: (process) pipe file descriptor from Runtime.exec not being closed
5070 // 6339493: (process) Runtime.exec does not close all file descriptors on Solaris 9
5071 //
5072 // Modern Linux kernels (after 2.6.23 2007) support O_CLOEXEC with open().
5073 // O_CLOEXEC is preferable to using FD_CLOEXEC on an open file descriptor
5074 // because it saves a system call and removes a small window where the flag
5075 // is unset. On ancient Linux kernels the O_CLOEXEC flag will be ignored
5076 // and we fall back to using FD_CLOEXEC (see below).
5077 #ifdef O_CLOEXEC
5078 oflag |= O_CLOEXEC;
5079 #endif
5080
5081 int fd = ::open64(path, oflag, mode);
5082 if (fd == -1) return -1;
5083
5084 //If the open succeeded, the file might still be a directory
5085 {
5086 struct stat64 buf64;
5087 int ret = ::fstat64(fd, &buf64);
5088 int st_mode = buf64.st_mode;
5089
5090 if (ret != -1) {
5091 if ((st_mode & S_IFMT) == S_IFDIR) {
5092 errno = EISDIR;
5093 ::close(fd);
5094 return -1;
5095 }
5096 } else {
5097 ::close(fd);
5098 return -1;
5099 }
5100 }
5101
5102 #ifdef FD_CLOEXEC
5103 // Validate that the use of the O_CLOEXEC flag on open above worked.
5104 // With recent kernels, we will perform this check exactly once.
5105 static sig_atomic_t O_CLOEXEC_is_known_to_work = 0;
5106 if (!O_CLOEXEC_is_known_to_work) {
5107 int flags = ::fcntl(fd, F_GETFD);
5108 if (flags != -1) {
5109 if ((flags & FD_CLOEXEC) != 0)
5110 O_CLOEXEC_is_known_to_work = 1;
5111 else
5112 ::fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
5113 }
5114 }
5115 #endif
5116
5117 return fd;
5118 }
5119
5120
5121 // create binary file, rewriting existing file if required
5122 int os::create_binary_file(const char* path, bool rewrite_existing) {
5123 int oflags = O_WRONLY | O_CREAT;
5124 if (!rewrite_existing) {
5125 oflags |= O_EXCL;
5126 }
5127 return ::open64(path, oflags, S_IREAD | S_IWRITE);
5128 }
5129
5130 // return current position of file pointer
5131 jlong os::current_file_offset(int fd) {
5132 return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR);
5133 }
5134
5135 // move file pointer to the specified offset
5136 jlong os::seek_to_file_offset(int fd, jlong offset) {
5137 return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET);
5138 }
5139
5140 // This code originates from JDK's sysAvailable
5141 // from src/solaris/hpi/src/native_threads/src/sys_api_td.c
5142
5143 int os::available(int fd, jlong *bytes) {
5144 jlong cur, end;
5145 int mode;
5146 struct stat64 buf64;
5147
5148 if (::fstat64(fd, &buf64) >= 0) {
5149 mode = buf64.st_mode;
5150 if (S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) {
5151 // XXX: is the following call interruptible? If so, this might
5152 // need to go through the INTERRUPT_IO() wrapper as for other
5153 // blocking, interruptible calls in this file.
5154 int n;
5155 if (::ioctl(fd, FIONREAD, &n) >= 0) {
5156 *bytes = n;
5157 return 1;
5158 }
5159 }
5160 }
5161 if ((cur = ::lseek64(fd, 0L, SEEK_CUR)) == -1) {
5162 return 0;
5163 } else if ((end = ::lseek64(fd, 0L, SEEK_END)) == -1) {
5164 return 0;
5165 } else if (::lseek64(fd, cur, SEEK_SET) == -1) {
5166 return 0;
5167 }
5168 *bytes = end - cur;
5169 return 1;
5170 }
5171
5172 // Map a block of memory.
5173 char* os::pd_map_memory(int fd, const char* file_name, size_t file_offset,
5174 char *addr, size_t bytes, bool read_only,
5175 bool allow_exec) {
5176 int prot;
5177 int flags = MAP_PRIVATE;
5178
5179 if (read_only) {
5180 prot = PROT_READ;
5181 } else {
5182 prot = PROT_READ | PROT_WRITE;
5183 }
5184
5185 if (allow_exec) {
5186 prot |= PROT_EXEC;
5187 }
5188
5189 if (addr != NULL) {
5190 flags |= MAP_FIXED;
5191 }
5192
5193 char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags,
5194 fd, file_offset);
5195 if (mapped_address == MAP_FAILED) {
5196 return NULL;
5197 }
5198 return mapped_address;
5199 }
5200
5201
5202 // Remap a block of memory.
5203 char* os::pd_remap_memory(int fd, const char* file_name, size_t file_offset,
5204 char *addr, size_t bytes, bool read_only,
5205 bool allow_exec) {
5206 // same as map_memory() on this OS
5207 return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only,
5208 allow_exec);
5209 }
5210
5211
5212 // Unmap a block of memory.
5213 bool os::pd_unmap_memory(char* addr, size_t bytes) {
5214 return munmap(addr, bytes) == 0;
5215 }
5216
5217 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time);
5218
5219 static clockid_t thread_cpu_clockid(Thread* thread) {
5220 pthread_t tid = thread->osthread()->pthread_id();
5221 clockid_t clockid;
5222
5223 // Get thread clockid
5224 int rc = os::Linux::pthread_getcpuclockid(tid, &clockid);
5225 assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code");
5226 return clockid;
5227 }
5228
5229 // current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool)
5230 // are used by JVM M&M and JVMTI to get user+sys or user CPU time
5231 // of a thread.
5232 //
5233 // current_thread_cpu_time() and thread_cpu_time(Thread*) returns
5234 // the fast estimate available on the platform.
5235
5236 jlong os::current_thread_cpu_time() {
5237 if (os::Linux::supports_fast_thread_cpu_time()) {
5238 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
5239 } else {
5240 // return user + sys since the cost is the same
5241 return slow_thread_cpu_time(Thread::current(), true /* user + sys */);
5242 }
5243 }
5244
5245 jlong os::thread_cpu_time(Thread* thread) {
5246 // consistent with what current_thread_cpu_time() returns
5247 if (os::Linux::supports_fast_thread_cpu_time()) {
5248 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread));
5249 } else {
5250 return slow_thread_cpu_time(thread, true /* user + sys */);
5251 }
5252 }
5253
5254 jlong os::current_thread_cpu_time(bool user_sys_cpu_time) {
5255 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
5256 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
5257 } else {
5258 return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time);
5259 }
5260 }
5261
5262 jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
5263 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
5264 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread));
5265 } else {
5266 return slow_thread_cpu_time(thread, user_sys_cpu_time);
5267 }
5268 }
5269
5270 // -1 on error.
5271 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
5272 pid_t tid = thread->osthread()->thread_id();
5273 char *s;
5274 char stat[2048];
5275 int statlen;
5276 char proc_name[64];
5277 int count;
5278 long sys_time, user_time;
5279 char cdummy;
5280 int idummy;
5281 long ldummy;
5282 FILE *fp;
5283
5284 snprintf(proc_name, 64, "/proc/self/task/%d/stat", tid);
5285 fp = fopen(proc_name, "r");
5286 if (fp == NULL) return -1;
5287 statlen = fread(stat, 1, 2047, fp);
5288 stat[statlen] = '\0';
5289 fclose(fp);
5290
5291 // Skip pid and the command string. Note that we could be dealing with
5292 // weird command names, e.g. user could decide to rename java launcher
5293 // to "java 1.4.2 :)", then the stat file would look like
5294 // 1234 (java 1.4.2 :)) R ... ...
5295 // We don't really need to know the command string, just find the last
5296 // occurrence of ")" and then start parsing from there. See bug 4726580.
5297 s = strrchr(stat, ')');
5298 if (s == NULL) return -1;
5299
5300 // Skip blank chars
5301 do { s++; } while (s && isspace(*s));
5302
5303 count = sscanf(s,"%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu",
5304 &cdummy, &idummy, &idummy, &idummy, &idummy, &idummy,
5305 &ldummy, &ldummy, &ldummy, &ldummy, &ldummy,
5306 &user_time, &sys_time);
5307 if (count != 13) return -1;
5308 if (user_sys_cpu_time) {
5309 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec);
5310 } else {
5311 return (jlong)user_time * (1000000000 / clock_tics_per_sec);
5312 }
5313 }
5314
5315 void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
5316 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits
5317 info_ptr->may_skip_backward = false; // elapsed time not wall time
5318 info_ptr->may_skip_forward = false; // elapsed time not wall time
5319 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned
5320 }
5321
5322 void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
5323 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits
5324 info_ptr->may_skip_backward = false; // elapsed time not wall time
5325 info_ptr->may_skip_forward = false; // elapsed time not wall time
5326 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned
5327 }
5328
5329 bool os::is_thread_cpu_time_supported() {
5330 return true;
5331 }
5332
5333 // System loadavg support. Returns -1 if load average cannot be obtained.
5334 // Linux doesn't yet have a (official) notion of processor sets,
5335 // so just return the system wide load average.
5336 int os::loadavg(double loadavg[], int nelem) {
5337 return ::getloadavg(loadavg, nelem);
5338 }
5339
5340 void os::pause() {
5341 char filename[MAX_PATH];
5342 if (PauseAtStartupFile && PauseAtStartupFile[0]) {
5343 jio_snprintf(filename, MAX_PATH, PauseAtStartupFile);
5344 } else {
5345 jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id());
5346 }
5347
5348 int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
5349 if (fd != -1) {
5350 struct stat buf;
5351 ::close(fd);
5352 while (::stat(filename, &buf) == 0) {
5353 (void)::poll(NULL, 0, 100);
5354 }
5355 } else {
5356 jio_fprintf(stderr,
5357 "Could not open pause file '%s', continuing immediately.\n", filename);
5358 }
5359 }
5360
5361
5362 // Refer to the comments in os_solaris.cpp park-unpark. The next two
5363 // comment paragraphs are worth repeating here:
5364 //
5365 // Assumption:
5366 // Only one parker can exist on an event, which is why we allocate
5367 // them per-thread. Multiple unparkers can coexist.
5368 //
5369 // _Event serves as a restricted-range semaphore.
5370 // -1 : thread is blocked, i.e. there is a waiter
5371 // 0 : neutral: thread is running or ready,
5372 // could have been signaled after a wait started
5373 // 1 : signaled - thread is running or ready
5374 //
5375 // Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can
5376 // hang indefinitely. For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable.
5377 // For specifics regarding the bug see GLIBC BUGID 261237 :
5378 // http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html.
5379 // Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future
5380 // will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar
5381 // is used. (The simple C test-case provided in the GLIBC bug report manifests the
5382 // hang). The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos()
5383 // and monitorenter when we're using 1-0 locking. All those operations may result in
5384 // calls to pthread_cond_timedwait(). Using LD_ASSUME_KERNEL to use an older version
5385 // of libpthread avoids the problem, but isn't practical.
5386 //
5387 // Possible remedies:
5388 //
5389 // 1. Establish a minimum relative wait time. 50 to 100 msecs seems to work.
5390 // This is palliative and probabilistic, however. If the thread is preempted
5391 // between the call to compute_abstime() and pthread_cond_timedwait(), more
5392 // than the minimum period may have passed, and the abstime may be stale (in the
5393 // past) resultin in a hang. Using this technique reduces the odds of a hang
5394 // but the JVM is still vulnerable, particularly on heavily loaded systems.
5395 //
5396 // 2. Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead
5397 // of the usual flag-condvar-mutex idiom. The write side of the pipe is set
5398 // NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo)
5399 // reduces to poll()+read(). This works well, but consumes 2 FDs per extant
5400 // thread.
5401 //
5402 // 3. Embargo pthread_cond_timedwait() and implement a native "chron" thread
5403 // that manages timeouts. We'd emulate pthread_cond_timedwait() by enqueuing
5404 // a timeout request to the chron thread and then blocking via pthread_cond_wait().
5405 // This also works well. In fact it avoids kernel-level scalability impediments
5406 // on certain platforms that don't handle lots of active pthread_cond_timedwait()
5407 // timers in a graceful fashion.
5408 //
5409 // 4. When the abstime value is in the past it appears that control returns
5410 // correctly from pthread_cond_timedwait(), but the condvar is left corrupt.
5411 // Subsequent timedwait/wait calls may hang indefinitely. Given that, we
5412 // can avoid the problem by reinitializing the condvar -- by cond_destroy()
5413 // followed by cond_init() -- after all calls to pthread_cond_timedwait().
5414 // It may be possible to avoid reinitialization by checking the return
5415 // value from pthread_cond_timedwait(). In addition to reinitializing the
5416 // condvar we must establish the invariant that cond_signal() is only called
5417 // within critical sections protected by the adjunct mutex. This prevents
5418 // cond_signal() from "seeing" a condvar that's in the midst of being
5419 // reinitialized or that is corrupt. Sadly, this invariant obviates the
5420 // desirable signal-after-unlock optimization that avoids futile context switching.
5421 //
5422 // I'm also concerned that some versions of NTPL might allocate an auxilliary
5423 // structure when a condvar is used or initialized. cond_destroy() would
5424 // release the helper structure. Our reinitialize-after-timedwait fix
5425 // put excessive stress on malloc/free and locks protecting the c-heap.
5426 //
5427 // We currently use (4). See the WorkAroundNTPLTimedWaitHang flag.
5428 // It may be possible to refine (4) by checking the kernel and NTPL verisons
5429 // and only enabling the work-around for vulnerable environments.
5430
5431 // utility to compute the abstime argument to timedwait:
5432 // millis is the relative timeout time
5433 // abstime will be the absolute timeout time
5434 // TODO: replace compute_abstime() with unpackTime()
5435
5436 static struct timespec* compute_abstime(timespec* abstime, jlong millis) {
5437 if (millis < 0) millis = 0;
5438
5439 jlong seconds = millis / 1000;
5440 millis %= 1000;
5441 if (seconds > 50000000) { // see man cond_timedwait(3T)
5442 seconds = 50000000;
5443 }
5444
5445 if (os::supports_monotonic_clock()) {
5446 struct timespec now;
5447 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now);
5448 assert_status(status == 0, status, "clock_gettime");
5449 abstime->tv_sec = now.tv_sec + seconds;
5450 long nanos = now.tv_nsec + millis * NANOSECS_PER_MILLISEC;
5451 if (nanos >= NANOSECS_PER_SEC) {
5452 abstime->tv_sec += 1;
5453 nanos -= NANOSECS_PER_SEC;
5454 }
5455 abstime->tv_nsec = nanos;
5456 } else {
5457 struct timeval now;
5458 int status = gettimeofday(&now, NULL);
5459 assert(status == 0, "gettimeofday");
5460 abstime->tv_sec = now.tv_sec + seconds;
5461 long usec = now.tv_usec + millis * 1000;
5462 if (usec >= 1000000) {
5463 abstime->tv_sec += 1;
5464 usec -= 1000000;
5465 }
5466 abstime->tv_nsec = usec * 1000;
5467 }
5468 return abstime;
5469 }
5470
5471 void os::PlatformEvent::park() { // AKA "down()"
5472 // Transitions for _Event:
5473 // -1 => -1 : illegal
5474 // 1 => 0 : pass - return immediately
5475 // 0 => -1 : block; then set _Event to 0 before returning
5476
5477 // Invariant: Only the thread associated with the Event/PlatformEvent
5478 // may call park().
5479 // TODO: assert that _Assoc != NULL or _Assoc == Self
5480 assert(_nParked == 0, "invariant");
5481
5482 int v;
5483 for (;;) {
5484 v = _Event;
5485 if (Atomic::cmpxchg(v-1, &_Event, v) == v) break;
5486 }
5487 guarantee(v >= 0, "invariant");
5488 if (v == 0) {
5489 // Do this the hard way by blocking ...
5490 int status = pthread_mutex_lock(_mutex);
5491 assert_status(status == 0, status, "mutex_lock");
5492 guarantee(_nParked == 0, "invariant");
5493 ++_nParked;
5494 while (_Event < 0) {
5495 status = pthread_cond_wait(_cond, _mutex);
5496 // for some reason, under 2.7 lwp_cond_wait() may return ETIME ...
5497 // Treat this the same as if the wait was interrupted
5498 if (status == ETIME) { status = EINTR; }
5499 assert_status(status == 0 || status == EINTR, status, "cond_wait");
5500 }
5501 --_nParked;
5502
5503 _Event = 0;
5504 status = pthread_mutex_unlock(_mutex);
5505 assert_status(status == 0, status, "mutex_unlock");
5506 // Paranoia to ensure our locked and lock-free paths interact
5507 // correctly with each other.
5508 OrderAccess::fence();
5509 }
5510 guarantee(_Event >= 0, "invariant");
5511 }
5512
5513 int os::PlatformEvent::park(jlong millis) {
5514 // Transitions for _Event:
5515 // -1 => -1 : illegal
5516 // 1 => 0 : pass - return immediately
5517 // 0 => -1 : block; then set _Event to 0 before returning
5518
5519 guarantee(_nParked == 0, "invariant");
5520
5521 int v;
5522 for (;;) {
5523 v = _Event;
5524 if (Atomic::cmpxchg(v-1, &_Event, v) == v) break;
5525 }
5526 guarantee(v >= 0, "invariant");
5527 if (v != 0) return OS_OK;
5528
5529 // We do this the hard way, by blocking the thread.
5530 // Consider enforcing a minimum timeout value.
5531 struct timespec abst;
5532 compute_abstime(&abst, millis);
5533
5534 int ret = OS_TIMEOUT;
5535 int status = pthread_mutex_lock(_mutex);
5536 assert_status(status == 0, status, "mutex_lock");
5537 guarantee(_nParked == 0, "invariant");
5538 ++_nParked;
5539
5540 // Object.wait(timo) will return because of
5541 // (a) notification
5542 // (b) timeout
5543 // (c) thread.interrupt
5544 //
5545 // Thread.interrupt and object.notify{All} both call Event::set.
5546 // That is, we treat thread.interrupt as a special case of notification.
5547 // We ignore spurious OS wakeups unless FilterSpuriousWakeups is false.
5548 // We assume all ETIME returns are valid.
5549 //
5550 // TODO: properly differentiate simultaneous notify+interrupt.
5551 // In that case, we should propagate the notify to another waiter.
5552
5553 while (_Event < 0) {
5554 status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst);
5555 if (status != 0 && WorkAroundNPTLTimedWaitHang) {
5556 pthread_cond_destroy(_cond);
5557 pthread_cond_init(_cond, os::Linux::condAttr());
5558 }
5559 assert_status(status == 0 || status == EINTR ||
5560 status == ETIME || status == ETIMEDOUT,
5561 status, "cond_timedwait");
5562 if (!FilterSpuriousWakeups) break; // previous semantics
5563 if (status == ETIME || status == ETIMEDOUT) break;
5564 // We consume and ignore EINTR and spurious wakeups.
5565 }
5566 --_nParked;
5567 if (_Event >= 0) {
5568 ret = OS_OK;
5569 }
5570 _Event = 0;
5571 status = pthread_mutex_unlock(_mutex);
5572 assert_status(status == 0, status, "mutex_unlock");
5573 assert(_nParked == 0, "invariant");
5574 // Paranoia to ensure our locked and lock-free paths interact
5575 // correctly with each other.
5576 OrderAccess::fence();
5577 return ret;
5578 }
5579
5580 void os::PlatformEvent::unpark() {
5581 // Transitions for _Event:
5582 // 0 => 1 : just return
5583 // 1 => 1 : just return
5584 // -1 => either 0 or 1; must signal target thread
5585 // That is, we can safely transition _Event from -1 to either
5586 // 0 or 1.
5587 // See also: "Semaphores in Plan 9" by Mullender & Cox
5588 //
5589 // Note: Forcing a transition from "-1" to "1" on an unpark() means
5590 // that it will take two back-to-back park() calls for the owning
5591 // thread to block. This has the benefit of forcing a spurious return
5592 // from the first park() call after an unpark() call which will help
5593 // shake out uses of park() and unpark() without condition variables.
5594
5595 if (Atomic::xchg(1, &_Event) >= 0) return;
5596
5597 // Wait for the thread associated with the event to vacate
5598 int status = pthread_mutex_lock(_mutex);
5599 assert_status(status == 0, status, "mutex_lock");
5600 int AnyWaiters = _nParked;
5601 assert(AnyWaiters == 0 || AnyWaiters == 1, "invariant");
5602 if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) {
5603 AnyWaiters = 0;
5604 pthread_cond_signal(_cond);
5605 }
5606 status = pthread_mutex_unlock(_mutex);
5607 assert_status(status == 0, status, "mutex_unlock");
5608 if (AnyWaiters != 0) {
5609 // Note that we signal() *after* dropping the lock for "immortal" Events.
5610 // This is safe and avoids a common class of futile wakeups. In rare
5611 // circumstances this can cause a thread to return prematurely from
5612 // cond_{timed}wait() but the spurious wakeup is benign and the victim
5613 // will simply re-test the condition and re-park itself.
5614 // This provides particular benefit if the underlying platform does not
5615 // provide wait morphing.
5616 status = pthread_cond_signal(_cond);
5617 assert_status(status == 0, status, "cond_signal");
5618 }
5619 }
5620
5621
5622 // JSR166
5623 // -------------------------------------------------------
5624
5625 // The solaris and linux implementations of park/unpark are fairly
5626 // conservative for now, but can be improved. They currently use a
5627 // mutex/condvar pair, plus a a count.
5628 // Park decrements count if > 0, else does a condvar wait. Unpark
5629 // sets count to 1 and signals condvar. Only one thread ever waits
5630 // on the condvar. Contention seen when trying to park implies that someone
5631 // is unparking you, so don't wait. And spurious returns are fine, so there
5632 // is no need to track notifications.
5633
5634 // This code is common to linux and solaris and will be moved to a
5635 // common place in dolphin.
5636 //
5637 // The passed in time value is either a relative time in nanoseconds
5638 // or an absolute time in milliseconds. Either way it has to be unpacked
5639 // into suitable seconds and nanoseconds components and stored in the
5640 // given timespec structure.
5641 // Given time is a 64-bit value and the time_t used in the timespec is only
5642 // a signed-32-bit value (except on 64-bit Linux) we have to watch for
5643 // overflow if times way in the future are given. Further on Solaris versions
5644 // prior to 10 there is a restriction (see cond_timedwait) that the specified
5645 // number of seconds, in abstime, is less than current_time + 100,000,000.
5646 // As it will be 28 years before "now + 100000000" will overflow we can
5647 // ignore overflow and just impose a hard-limit on seconds using the value
5648 // of "now + 100,000,000". This places a limit on the timeout of about 3.17
5649 // years from "now".
5650
5651 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) {
5652 assert(time > 0, "convertTime");
5653 time_t max_secs = 0;
5654
5655 if (!os::supports_monotonic_clock() || isAbsolute) {
5656 struct timeval now;
5657 int status = gettimeofday(&now, NULL);
5658 assert(status == 0, "gettimeofday");
5659
5660 max_secs = now.tv_sec + MAX_SECS;
5661
5662 if (isAbsolute) {
5663 jlong secs = time / 1000;
5664 if (secs > max_secs) {
5665 absTime->tv_sec = max_secs;
5666 } else {
5667 absTime->tv_sec = secs;
5668 }
5669 absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC;
5670 } else {
5671 jlong secs = time / NANOSECS_PER_SEC;
5672 if (secs >= MAX_SECS) {
5673 absTime->tv_sec = max_secs;
5674 absTime->tv_nsec = 0;
5675 } else {
5676 absTime->tv_sec = now.tv_sec + secs;
5677 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000;
5678 if (absTime->tv_nsec >= NANOSECS_PER_SEC) {
5679 absTime->tv_nsec -= NANOSECS_PER_SEC;
5680 ++absTime->tv_sec; // note: this must be <= max_secs
5681 }
5682 }
5683 }
5684 } else {
5685 // must be relative using monotonic clock
5686 struct timespec now;
5687 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now);
5688 assert_status(status == 0, status, "clock_gettime");
5689 max_secs = now.tv_sec + MAX_SECS;
5690 jlong secs = time / NANOSECS_PER_SEC;
5691 if (secs >= MAX_SECS) {
5692 absTime->tv_sec = max_secs;
5693 absTime->tv_nsec = 0;
5694 } else {
5695 absTime->tv_sec = now.tv_sec + secs;
5696 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_nsec;
5697 if (absTime->tv_nsec >= NANOSECS_PER_SEC) {
5698 absTime->tv_nsec -= NANOSECS_PER_SEC;
5699 ++absTime->tv_sec; // note: this must be <= max_secs
5700 }
5701 }
5702 }
5703 assert(absTime->tv_sec >= 0, "tv_sec < 0");
5704 assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs");
5705 assert(absTime->tv_nsec >= 0, "tv_nsec < 0");
5706 assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec");
5707 }
5708
5709 void Parker::park(bool isAbsolute, jlong time) {
5710 // Ideally we'd do something useful while spinning, such
5711 // as calling unpackTime().
5712
5713 // Optional fast-path check:
5714 // Return immediately if a permit is available.
5715 // We depend on Atomic::xchg() having full barrier semantics
5716 // since we are doing a lock-free update to _counter.
5717 if (Atomic::xchg(0, &_counter) > 0) return;
5718
5719 Thread* thread = Thread::current();
5720 assert(thread->is_Java_thread(), "Must be JavaThread");
5721 JavaThread *jt = (JavaThread *)thread;
5722
5723 // Optional optimization -- avoid state transitions if there's an interrupt pending.
5724 // Check interrupt before trying to wait
5725 if (Thread::is_interrupted(thread, false)) {
5726 return;
5727 }
5728
5729 // Next, demultiplex/decode time arguments
5730 timespec absTime;
5731 if (time < 0 || (isAbsolute && time == 0)) { // don't wait at all
5732 return;
5733 }
5734 if (time > 0) {
5735 unpackTime(&absTime, isAbsolute, time);
5736 }
5737
5738
5739 // Enter safepoint region
5740 // Beware of deadlocks such as 6317397.
5741 // The per-thread Parker:: mutex is a classic leaf-lock.
5742 // In particular a thread must never block on the Threads_lock while
5743 // holding the Parker:: mutex. If safepoints are pending both the
5744 // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock.
5745 ThreadBlockInVM tbivm(jt);
5746
5747 // Don't wait if cannot get lock since interference arises from
5748 // unblocking. Also. check interrupt before trying wait
5749 if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) {
5750 return;
5751 }
5752
5753 int status;
5754 if (_counter > 0) { // no wait needed
5755 _counter = 0;
5756 status = pthread_mutex_unlock(_mutex);
5757 assert(status == 0, "invariant");
5758 // Paranoia to ensure our locked and lock-free paths interact
5759 // correctly with each other and Java-level accesses.
5760 OrderAccess::fence();
5761 return;
5762 }
5763
5764 #ifdef ASSERT
5765 // Don't catch signals while blocked; let the running threads have the signals.
5766 // (This allows a debugger to break into the running thread.)
5767 sigset_t oldsigs;
5768 sigset_t* allowdebug_blocked = os::Linux::allowdebug_blocked_signals();
5769 pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs);
5770 #endif
5771
5772 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */);
5773 jt->set_suspend_equivalent();
5774 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
5775
5776 assert(_cur_index == -1, "invariant");
5777 if (time == 0) {
5778 _cur_index = REL_INDEX; // arbitrary choice when not timed
5779 status = pthread_cond_wait(&_cond[_cur_index], _mutex);
5780 } else {
5781 _cur_index = isAbsolute ? ABS_INDEX : REL_INDEX;
5782 status = os::Linux::safe_cond_timedwait(&_cond[_cur_index], _mutex, &absTime);
5783 if (status != 0 && WorkAroundNPTLTimedWaitHang) {
5784 pthread_cond_destroy(&_cond[_cur_index]);
5785 pthread_cond_init(&_cond[_cur_index], isAbsolute ? NULL : os::Linux::condAttr());
5786 }
5787 }
5788 _cur_index = -1;
5789 assert_status(status == 0 || status == EINTR ||
5790 status == ETIME || status == ETIMEDOUT,
5791 status, "cond_timedwait");
5792
5793 #ifdef ASSERT
5794 pthread_sigmask(SIG_SETMASK, &oldsigs, NULL);
5795 #endif
5796
5797 _counter = 0;
5798 status = pthread_mutex_unlock(_mutex);
5799 assert_status(status == 0, status, "invariant");
5800 // Paranoia to ensure our locked and lock-free paths interact
5801 // correctly with each other and Java-level accesses.
5802 OrderAccess::fence();
5803
5804 // If externally suspended while waiting, re-suspend
5805 if (jt->handle_special_suspend_equivalent_condition()) {
5806 jt->java_suspend_self();
5807 }
5808 }
5809
5810 void Parker::unpark() {
5811 int status = pthread_mutex_lock(_mutex);
5812 assert(status == 0, "invariant");
5813 const int s = _counter;
5814 _counter = 1;
5815 if (s < 1) {
5816 // thread might be parked
5817 if (_cur_index != -1) {
5818 // thread is definitely parked
5819 if (WorkAroundNPTLTimedWaitHang) {
5820 status = pthread_cond_signal(&_cond[_cur_index]);
5821 assert(status == 0, "invariant");
5822 status = pthread_mutex_unlock(_mutex);
5823 assert(status == 0, "invariant");
5824 } else {
5825 status = pthread_mutex_unlock(_mutex);
5826 assert(status == 0, "invariant");
5827 status = pthread_cond_signal(&_cond[_cur_index]);
5828 assert(status == 0, "invariant");
5829 }
5830 } else {
5831 pthread_mutex_unlock(_mutex);
5832 assert(status == 0, "invariant");
5833 }
5834 } else {
5835 pthread_mutex_unlock(_mutex);
5836 assert(status == 0, "invariant");
5837 }
5838 }
5839
5840
5841 extern char** environ;
5842
5843 #ifndef __NR_fork
5844 #define __NR_fork IA32_ONLY(2) IA64_ONLY(not defined) AMD64_ONLY(57) AARCH64_ONLY(1079)
5845 #endif
5846
5847 #ifndef __NR_execve
5848 #define __NR_execve IA32_ONLY(11) IA64_ONLY(1033) AMD64_ONLY(59) AARCH64_ONLY(221)
5849 #endif
5850
5851 // Run the specified command in a separate process. Return its exit value,
5852 // or -1 on failure (e.g. can't fork a new process).
5853 // Unlike system(), this function can be called from signal handler. It
5854 // doesn't block SIGINT et al.
5855 int os::fork_and_exec(char* cmd) {
5856 const char * argv[4] = {"sh", "-c", cmd, NULL};
5857
5858 // fork() in LinuxThreads/NPTL is not async-safe. It needs to run
5859 // pthread_atfork handlers and reset pthread library. All we need is a
5860 // separate process to execve. Make a direct syscall to fork process.
5861 // On IA64 there's no fork syscall, we have to use fork() and hope for
5862 // the best...
5863 pid_t pid = NOT_IA64(syscall(__NR_fork);)
5864 IA64_ONLY(fork();)
5865
5866 if (pid < 0) {
5867 // fork failed
5868 return -1;
5869
5870 } else if (pid == 0) {
5871 // child process
5872
5873 // execve() in LinuxThreads will call pthread_kill_other_threads_np()
5874 // first to kill every thread on the thread list. Because this list is
5875 // not reset by fork() (see notes above), execve() will instead kill
5876 // every thread in the parent process. We know this is the only thread
5877 // in the new process, so make a system call directly.
5878 // IA64 should use normal execve() from glibc to match the glibc fork()
5879 // above.
5880 NOT_IA64(syscall(__NR_execve, "/bin/sh", argv, environ);)
5881 IA64_ONLY(execve("/bin/sh", (char* const*)argv, environ);)
5882
5883 // execve failed
5884 _exit(-1);
5885
5886 } else {
5887 // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't
5888 // care about the actual exit code, for now.
5889
5890 int status;
5891
5892 // Wait for the child process to exit. This returns immediately if
5893 // the child has already exited. */
5894 while (waitpid(pid, &status, 0) < 0) {
5895 switch (errno) {
5896 case ECHILD: return 0;
5897 case EINTR: break;
5898 default: return -1;
5899 }
5900 }
5901
5902 if (WIFEXITED(status)) {
5903 // The child exited normally; get its exit code.
5904 return WEXITSTATUS(status);
5905 } else if (WIFSIGNALED(status)) {
5906 // The child exited because of a signal
5907 // The best value to return is 0x80 + signal number,
5908 // because that is what all Unix shells do, and because
5909 // it allows callers to distinguish between process exit and
5910 // process death by signal.
5911 return 0x80 + WTERMSIG(status);
5912 } else {
5913 // Unknown exit code; pass it through
5914 return status;
5915 }
5916 }
5917 }
5918
5919 // is_headless_jre()
5920 //
5921 // Test for the existence of xawt/libmawt.so or libawt_xawt.so
5922 // in order to report if we are running in a headless jre
5923 //
5924 // Since JDK8 xawt/libmawt.so was moved into the same directory
5925 // as libawt.so, and renamed libawt_xawt.so
5926 //
5927 bool os::is_headless_jre() {
5928 struct stat statbuf;
5929 char buf[MAXPATHLEN];
5930 char libmawtpath[MAXPATHLEN];
5931 const char *xawtstr = "/xawt/libmawt.so";
5932 const char *new_xawtstr = "/libawt_xawt.so";
5933 char *p;
5934
5935 // Get path to libjvm.so
5936 os::jvm_path(buf, sizeof(buf));
5937
5938 // Get rid of libjvm.so
5939 p = strrchr(buf, '/');
5940 if (p == NULL) {
5941 return false;
5942 } else {
5943 *p = '\0';
5944 }
5945
5946 // Get rid of client or server
5947 p = strrchr(buf, '/');
5948 if (p == NULL) {
5949 return false;
5950 } else {
5951 *p = '\0';
5952 }
5953
5954 // check xawt/libmawt.so
5955 strcpy(libmawtpath, buf);
5956 strcat(libmawtpath, xawtstr);
5957 if (::stat(libmawtpath, &statbuf) == 0) return false;
5958
5959 // check libawt_xawt.so
5960 strcpy(libmawtpath, buf);
5961 strcat(libmawtpath, new_xawtstr);
5962 if (::stat(libmawtpath, &statbuf) == 0) return false;
5963
5964 return true;
5965 }
5966
5967 // Get the default path to the core file
5968 // Returns the length of the string
5969 int os::get_core_path(char* buffer, size_t bufferSize) {
5970 /*
5971 * Max length of /proc/sys/kernel/core_pattern is 128 characters.
5972 * See https://www.kernel.org/doc/Documentation/sysctl/kernel.txt
5973 */
5974 const int core_pattern_len = 129;
5975 char core_pattern[core_pattern_len] = {0};
5976
5977 int core_pattern_file = ::open("/proc/sys/kernel/core_pattern", O_RDONLY);
5978 if (core_pattern_file != -1) {
5979 ssize_t ret = ::read(core_pattern_file, core_pattern, core_pattern_len);
5980 ::close(core_pattern_file);
5981
5982 if (ret > 0) {
5983 char *last_char = core_pattern + strlen(core_pattern) - 1;
5984
5985 if (*last_char == '\n') {
5986 *last_char = '\0';
5987 }
5988 }
5989 }
5990
5991 if (strlen(core_pattern) == 0) {
5992 return -1;
5993 }
5994
5995 char *pid_pos = strstr(core_pattern, "%p");
5996 int written;
5997
5998 if (core_pattern[0] == '/') {
5999 written = jio_snprintf(buffer, bufferSize, core_pattern);
6000 } else {
6001 char cwd[PATH_MAX];
6002
6003 const char* p = get_current_directory(cwd, PATH_MAX);
6004 if (p == NULL) {
6005 return -1;
6006 }
6007
6008 if (core_pattern[0] == '|') {
6009 written = jio_snprintf(buffer, bufferSize,
6010 "\"%s\" (or dumping to %s/core.%d)",
6011 &core_pattern[1], p, current_process_id());
6012 } else {
6013 written = jio_snprintf(buffer, bufferSize, "%s/%s", p, core_pattern);
6014 }
6015 }
6016
6017 if (written < 0) {
6018 return -1;
6019 }
6020
6021 if (((size_t)written < bufferSize) && (pid_pos == NULL) && (core_pattern[0] != '|')) {
6022 int core_uses_pid_file = ::open("/proc/sys/kernel/core_uses_pid", O_RDONLY);
6023
6024 if (core_uses_pid_file != -1) {
6025 char core_uses_pid = 0;
6026 ssize_t ret = ::read(core_uses_pid_file, &core_uses_pid, 1);
6027 ::close(core_uses_pid_file);
6028
6029 if (core_uses_pid == '1') {
6030 jio_snprintf(buffer + written, bufferSize - written,
6031 ".%d", current_process_id());
6032 }
6033 }
6034 }
6035
6036 return strlen(buffer);
6037 }
6038
6039 /////////////// Unit tests ///////////////
6040
6041 #ifndef PRODUCT
6042
6043 #define test_log(...) \
6044 do { \
6045 if (VerboseInternalVMTests) { \
6046 tty->print_cr(__VA_ARGS__); \
6047 tty->flush(); \
6048 } \
6049 } while (false)
6050
6051 class TestReserveMemorySpecial : AllStatic {
6052 public:
6053 static void small_page_write(void* addr, size_t size) {
6054 size_t page_size = os::vm_page_size();
6055
6056 char* end = (char*)addr + size;
6057 for (char* p = (char*)addr; p < end; p += page_size) {
6058 *p = 1;
6059 }
6060 }
6061
6062 static void test_reserve_memory_special_huge_tlbfs_only(size_t size) {
6063 if (!UseHugeTLBFS) {
6064 return;
6065 }
6066
6067 test_log("test_reserve_memory_special_huge_tlbfs_only(" SIZE_FORMAT ")", size);
6068
6069 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_only(size, NULL, false);
6070
6071 if (addr != NULL) {
6072 small_page_write(addr, size);
6073
6074 os::Linux::release_memory_special_huge_tlbfs(addr, size);
6075 }
6076 }
6077
6078 static void test_reserve_memory_special_huge_tlbfs_only() {
6079 if (!UseHugeTLBFS) {
6080 return;
6081 }
6082
6083 size_t lp = os::large_page_size();
6084
6085 for (size_t size = lp; size <= lp * 10; size += lp) {
6086 test_reserve_memory_special_huge_tlbfs_only(size);
6087 }
6088 }
6089
6090 static void test_reserve_memory_special_huge_tlbfs_mixed(size_t size, size_t alignment) {
6091 if (!UseHugeTLBFS) {
6092 return;
6093 }
6094
6095 test_log("test_reserve_memory_special_huge_tlbfs_mixed(" SIZE_FORMAT ", " SIZE_FORMAT ")",
6096 size, alignment);
6097
6098 assert(size >= os::large_page_size(), "Incorrect input to test");
6099
6100 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, NULL, false);
6101
6102 if (addr != NULL) {
6103 small_page_write(addr, size);
6104
6105 os::Linux::release_memory_special_huge_tlbfs(addr, size);
6106 }
6107 }
6108
6109 static void test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(size_t size) {
6110 size_t lp = os::large_page_size();
6111 size_t ag = os::vm_allocation_granularity();
6112
6113 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) {
6114 test_reserve_memory_special_huge_tlbfs_mixed(size, alignment);
6115 }
6116 }
6117
6118 static void test_reserve_memory_special_huge_tlbfs_mixed() {
6119 size_t lp = os::large_page_size();
6120 size_t ag = os::vm_allocation_granularity();
6121
6122 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp);
6123 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + ag);
6124 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + lp / 2);
6125 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2);
6126 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 + ag);
6127 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 - ag);
6128 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 + lp / 2);
6129 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10);
6130 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10 + lp / 2);
6131 }
6132
6133 static void test_reserve_memory_special_huge_tlbfs() {
6134 if (!UseHugeTLBFS) {
6135 return;
6136 }
6137
6138 test_reserve_memory_special_huge_tlbfs_only();
6139 test_reserve_memory_special_huge_tlbfs_mixed();
6140 }
6141
6142 static void test_reserve_memory_special_shm(size_t size, size_t alignment) {
6143 if (!UseSHM) {
6144 return;
6145 }
6146
6147 test_log("test_reserve_memory_special_shm(" SIZE_FORMAT ", " SIZE_FORMAT ")", size, alignment);
6148
6149 char* addr = os::Linux::reserve_memory_special_shm(size, alignment, NULL, false);
6150
6151 if (addr != NULL) {
6152 assert(is_ptr_aligned(addr, alignment), "Check");
6153 assert(is_ptr_aligned(addr, os::large_page_size()), "Check");
6154
6155 small_page_write(addr, size);
6156
6157 os::Linux::release_memory_special_shm(addr, size);
6158 }
6159 }
6160
6161 static void test_reserve_memory_special_shm() {
6162 size_t lp = os::large_page_size();
6163 size_t ag = os::vm_allocation_granularity();
6164
6165 for (size_t size = ag; size < lp * 3; size += ag) {
6166 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) {
6167 test_reserve_memory_special_shm(size, alignment);
6168 }
6169 }
6170 }
6171
6172 static void test() {
6173 test_reserve_memory_special_huge_tlbfs();
6174 test_reserve_memory_special_shm();
6175 }
6176 };
6177
6178 void TestReserveMemorySpecial_test() {
6179 TestReserveMemorySpecial::test();
6180 }
6181
6182 #endif