Thu, 25 Apr 2013 11:02:32 -0700
8012260: ciReplay: Include PID into the name of replay data file
Reviewed-by: kvn, twisti
1 /*
2 * Copyright (c) 1999, 2013, 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 */
25 // no precompiled headers
26 #include "classfile/classLoader.hpp"
27 #include "classfile/systemDictionary.hpp"
28 #include "classfile/vmSymbols.hpp"
29 #include "code/icBuffer.hpp"
30 #include "code/vtableStubs.hpp"
31 #include "compiler/compileBroker.hpp"
32 #include "compiler/disassembler.hpp"
33 #include "interpreter/interpreter.hpp"
34 #include "jvm_linux.h"
35 #include "memory/allocation.inline.hpp"
36 #include "memory/filemap.hpp"
37 #include "mutex_linux.inline.hpp"
38 #include "oops/oop.inline.hpp"
39 #include "os_share_linux.hpp"
40 #include "prims/jniFastGetField.hpp"
41 #include "prims/jvm.h"
42 #include "prims/jvm_misc.hpp"
43 #include "runtime/arguments.hpp"
44 #include "runtime/extendedPC.hpp"
45 #include "runtime/globals.hpp"
46 #include "runtime/interfaceSupport.hpp"
47 #include "runtime/init.hpp"
48 #include "runtime/java.hpp"
49 #include "runtime/javaCalls.hpp"
50 #include "runtime/mutexLocker.hpp"
51 #include "runtime/objectMonitor.hpp"
52 #include "runtime/osThread.hpp"
53 #include "runtime/perfMemory.hpp"
54 #include "runtime/sharedRuntime.hpp"
55 #include "runtime/statSampler.hpp"
56 #include "runtime/stubRoutines.hpp"
57 #include "runtime/thread.inline.hpp"
58 #include "runtime/threadCritical.hpp"
59 #include "runtime/timer.hpp"
60 #include "services/attachListener.hpp"
61 #include "services/memTracker.hpp"
62 #include "services/runtimeService.hpp"
63 #include "utilities/decoder.hpp"
64 #include "utilities/defaultStream.hpp"
65 #include "utilities/events.hpp"
66 #include "utilities/elfFile.hpp"
67 #include "utilities/growableArray.hpp"
68 #include "utilities/vmError.hpp"
70 // put OS-includes here
71 # include <sys/types.h>
72 # include <sys/mman.h>
73 # include <sys/stat.h>
74 # include <sys/select.h>
75 # include <pthread.h>
76 # include <signal.h>
77 # include <errno.h>
78 # include <dlfcn.h>
79 # include <stdio.h>
80 # include <unistd.h>
81 # include <sys/resource.h>
82 # include <pthread.h>
83 # include <sys/stat.h>
84 # include <sys/time.h>
85 # include <sys/times.h>
86 # include <sys/utsname.h>
87 # include <sys/socket.h>
88 # include <sys/wait.h>
89 # include <pwd.h>
90 # include <poll.h>
91 # include <semaphore.h>
92 # include <fcntl.h>
93 # include <string.h>
94 # include <syscall.h>
95 # include <sys/sysinfo.h>
96 # include <gnu/libc-version.h>
97 # include <sys/ipc.h>
98 # include <sys/shm.h>
99 # include <link.h>
100 # include <stdint.h>
101 # include <inttypes.h>
102 # include <sys/ioctl.h>
104 #define MAX_PATH (2 * K)
106 // for timer info max values which include all bits
107 #define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF)
109 #define LARGEPAGES_BIT (1 << 6)
110 ////////////////////////////////////////////////////////////////////////////////
111 // global variables
112 julong os::Linux::_physical_memory = 0;
114 address os::Linux::_initial_thread_stack_bottom = NULL;
115 uintptr_t os::Linux::_initial_thread_stack_size = 0;
117 int (*os::Linux::_clock_gettime)(clockid_t, struct timespec *) = NULL;
118 int (*os::Linux::_pthread_getcpuclockid)(pthread_t, clockid_t *) = NULL;
119 Mutex* os::Linux::_createThread_lock = NULL;
120 pthread_t os::Linux::_main_thread;
121 int os::Linux::_page_size = -1;
122 bool os::Linux::_is_floating_stack = false;
123 bool os::Linux::_is_NPTL = false;
124 bool os::Linux::_supports_fast_thread_cpu_time = false;
125 const char * os::Linux::_glibc_version = NULL;
126 const char * os::Linux::_libpthread_version = NULL;
128 static jlong initial_time_count=0;
130 static int clock_tics_per_sec = 100;
132 // For diagnostics to print a message once. see run_periodic_checks
133 static sigset_t check_signal_done;
134 static bool check_signals = true;;
136 static pid_t _initial_pid = 0;
138 /* Signal number used to suspend/resume a thread */
140 /* do not use any signal number less than SIGSEGV, see 4355769 */
141 static int SR_signum = SIGUSR2;
142 sigset_t SR_sigset;
144 /* Used to protect dlsym() calls */
145 static pthread_mutex_t dl_mutex;
147 #ifdef JAVASE_EMBEDDED
148 class MemNotifyThread: public Thread {
149 friend class VMStructs;
150 public:
151 virtual void run();
153 private:
154 static MemNotifyThread* _memnotify_thread;
155 int _fd;
157 public:
159 // Constructor
160 MemNotifyThread(int fd);
162 // Tester
163 bool is_memnotify_thread() const { return true; }
165 // Printing
166 char* name() const { return (char*)"Linux MemNotify Thread"; }
168 // Returns the single instance of the MemNotifyThread
169 static MemNotifyThread* memnotify_thread() { return _memnotify_thread; }
171 // Create and start the single instance of MemNotifyThread
172 static void start();
173 };
174 #endif // JAVASE_EMBEDDED
176 // utility functions
178 static int SR_initialize();
180 julong os::available_memory() {
181 return Linux::available_memory();
182 }
184 julong os::Linux::available_memory() {
185 // values in struct sysinfo are "unsigned long"
186 struct sysinfo si;
187 sysinfo(&si);
189 return (julong)si.freeram * si.mem_unit;
190 }
192 julong os::physical_memory() {
193 return Linux::physical_memory();
194 }
196 ////////////////////////////////////////////////////////////////////////////////
197 // environment support
199 bool os::getenv(const char* name, char* buf, int len) {
200 const char* val = ::getenv(name);
201 if (val != NULL && strlen(val) < (size_t)len) {
202 strcpy(buf, val);
203 return true;
204 }
205 if (len > 0) buf[0] = 0; // return a null string
206 return false;
207 }
210 // Return true if user is running as root.
212 bool os::have_special_privileges() {
213 static bool init = false;
214 static bool privileges = false;
215 if (!init) {
216 privileges = (getuid() != geteuid()) || (getgid() != getegid());
217 init = true;
218 }
219 return privileges;
220 }
223 #ifndef SYS_gettid
224 // i386: 224, ia64: 1105, amd64: 186, sparc 143
225 #ifdef __ia64__
226 #define SYS_gettid 1105
227 #elif __i386__
228 #define SYS_gettid 224
229 #elif __amd64__
230 #define SYS_gettid 186
231 #elif __sparc__
232 #define SYS_gettid 143
233 #else
234 #error define gettid for the arch
235 #endif
236 #endif
238 // Cpu architecture string
239 #if defined(ZERO)
240 static char cpu_arch[] = ZERO_LIBARCH;
241 #elif defined(IA64)
242 static char cpu_arch[] = "ia64";
243 #elif defined(IA32)
244 static char cpu_arch[] = "i386";
245 #elif defined(AMD64)
246 static char cpu_arch[] = "amd64";
247 #elif defined(ARM)
248 static char cpu_arch[] = "arm";
249 #elif defined(PPC)
250 static char cpu_arch[] = "ppc";
251 #elif defined(SPARC)
252 # ifdef _LP64
253 static char cpu_arch[] = "sparcv9";
254 # else
255 static char cpu_arch[] = "sparc";
256 # endif
257 #else
258 #error Add appropriate cpu_arch setting
259 #endif
262 // pid_t gettid()
263 //
264 // Returns the kernel thread id of the currently running thread. Kernel
265 // thread id is used to access /proc.
266 //
267 // (Note that getpid() on LinuxThreads returns kernel thread id too; but
268 // on NPTL, it returns the same pid for all threads, as required by POSIX.)
269 //
270 pid_t os::Linux::gettid() {
271 int rslt = syscall(SYS_gettid);
272 if (rslt == -1) {
273 // old kernel, no NPTL support
274 return getpid();
275 } else {
276 return (pid_t)rslt;
277 }
278 }
280 // Most versions of linux have a bug where the number of processors are
281 // determined by looking at the /proc file system. In a chroot environment,
282 // the system call returns 1. This causes the VM to act as if it is
283 // a single processor and elide locking (see is_MP() call).
284 static bool unsafe_chroot_detected = false;
285 static const char *unstable_chroot_error = "/proc file system not found.\n"
286 "Java may be unstable running multithreaded in a chroot "
287 "environment on Linux when /proc filesystem is not mounted.";
289 void os::Linux::initialize_system_info() {
290 set_processor_count(sysconf(_SC_NPROCESSORS_CONF));
291 if (processor_count() == 1) {
292 pid_t pid = os::Linux::gettid();
293 char fname[32];
294 jio_snprintf(fname, sizeof(fname), "/proc/%d", pid);
295 FILE *fp = fopen(fname, "r");
296 if (fp == NULL) {
297 unsafe_chroot_detected = true;
298 } else {
299 fclose(fp);
300 }
301 }
302 _physical_memory = (julong)sysconf(_SC_PHYS_PAGES) * (julong)sysconf(_SC_PAGESIZE);
303 assert(processor_count() > 0, "linux error");
304 }
306 void os::init_system_properties_values() {
307 // char arch[12];
308 // sysinfo(SI_ARCHITECTURE, arch, sizeof(arch));
310 // The next steps are taken in the product version:
311 //
312 // Obtain the JAVA_HOME value from the location of libjvm.so.
313 // This library should be located at:
314 // <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm.so.
315 //
316 // If "/jre/lib/" appears at the right place in the path, then we
317 // assume libjvm.so is installed in a JDK and we use this path.
318 //
319 // Otherwise exit with message: "Could not create the Java virtual machine."
320 //
321 // The following extra steps are taken in the debugging version:
322 //
323 // If "/jre/lib/" does NOT appear at the right place in the path
324 // instead of exit check for $JAVA_HOME environment variable.
325 //
326 // If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>,
327 // then we append a fake suffix "hotspot/libjvm.so" to this path so
328 // it looks like libjvm.so is installed there
329 // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm.so.
330 //
331 // Otherwise exit.
332 //
333 // Important note: if the location of libjvm.so changes this
334 // code needs to be changed accordingly.
336 // The next few definitions allow the code to be verbatim:
337 #define malloc(n) (char*)NEW_C_HEAP_ARRAY(char, (n), mtInternal)
338 #define getenv(n) ::getenv(n)
340 /*
341 * See ld(1):
342 * The linker uses the following search paths to locate required
343 * shared libraries:
344 * 1: ...
345 * ...
346 * 7: The default directories, normally /lib and /usr/lib.
347 */
348 #if defined(AMD64) || defined(_LP64) && (defined(SPARC) || defined(PPC) || defined(S390))
349 #define DEFAULT_LIBPATH "/usr/lib64:/lib64:/lib:/usr/lib"
350 #else
351 #define DEFAULT_LIBPATH "/lib:/usr/lib"
352 #endif
354 #define EXTENSIONS_DIR "/lib/ext"
355 #define ENDORSED_DIR "/lib/endorsed"
356 #define REG_DIR "/usr/java/packages"
358 {
359 /* sysclasspath, java_home, dll_dir */
360 {
361 char *home_path;
362 char *dll_path;
363 char *pslash;
364 char buf[MAXPATHLEN];
365 os::jvm_path(buf, sizeof(buf));
367 // Found the full path to libjvm.so.
368 // Now cut the path to <java_home>/jre if we can.
369 *(strrchr(buf, '/')) = '\0'; /* get rid of /libjvm.so */
370 pslash = strrchr(buf, '/');
371 if (pslash != NULL)
372 *pslash = '\0'; /* get rid of /{client|server|hotspot} */
373 dll_path = malloc(strlen(buf) + 1);
374 if (dll_path == NULL)
375 return;
376 strcpy(dll_path, buf);
377 Arguments::set_dll_dir(dll_path);
379 if (pslash != NULL) {
380 pslash = strrchr(buf, '/');
381 if (pslash != NULL) {
382 *pslash = '\0'; /* get rid of /<arch> */
383 pslash = strrchr(buf, '/');
384 if (pslash != NULL)
385 *pslash = '\0'; /* get rid of /lib */
386 }
387 }
389 home_path = malloc(strlen(buf) + 1);
390 if (home_path == NULL)
391 return;
392 strcpy(home_path, buf);
393 Arguments::set_java_home(home_path);
395 if (!set_boot_path('/', ':'))
396 return;
397 }
399 /*
400 * Where to look for native libraries
401 *
402 * Note: Due to a legacy implementation, most of the library path
403 * is set in the launcher. This was to accomodate linking restrictions
404 * on legacy Linux implementations (which are no longer supported).
405 * Eventually, all the library path setting will be done here.
406 *
407 * However, to prevent the proliferation of improperly built native
408 * libraries, the new path component /usr/java/packages is added here.
409 * Eventually, all the library path setting will be done here.
410 */
411 {
412 char *ld_library_path;
414 /*
415 * Construct the invariant part of ld_library_path. Note that the
416 * space for the colon and the trailing null are provided by the
417 * nulls included by the sizeof operator (so actually we allocate
418 * a byte more than necessary).
419 */
420 ld_library_path = (char *) malloc(sizeof(REG_DIR) + sizeof("/lib/") +
421 strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH));
422 sprintf(ld_library_path, REG_DIR "/lib/%s:" DEFAULT_LIBPATH, cpu_arch);
424 /*
425 * Get the user setting of LD_LIBRARY_PATH, and prepended it. It
426 * should always exist (until the legacy problem cited above is
427 * addressed).
428 */
429 char *v = getenv("LD_LIBRARY_PATH");
430 if (v != NULL) {
431 char *t = ld_library_path;
432 /* That's +1 for the colon and +1 for the trailing '\0' */
433 ld_library_path = (char *) malloc(strlen(v) + 1 + strlen(t) + 1);
434 sprintf(ld_library_path, "%s:%s", v, t);
435 }
436 Arguments::set_library_path(ld_library_path);
437 }
439 /*
440 * Extensions directories.
441 *
442 * Note that the space for the colon and the trailing null are provided
443 * by the nulls included by the sizeof operator (so actually one byte more
444 * than necessary is allocated).
445 */
446 {
447 char *buf = malloc(strlen(Arguments::get_java_home()) +
448 sizeof(EXTENSIONS_DIR) + sizeof(REG_DIR) + sizeof(EXTENSIONS_DIR));
449 sprintf(buf, "%s" EXTENSIONS_DIR ":" REG_DIR EXTENSIONS_DIR,
450 Arguments::get_java_home());
451 Arguments::set_ext_dirs(buf);
452 }
454 /* Endorsed standards default directory. */
455 {
456 char * buf;
457 buf = malloc(strlen(Arguments::get_java_home()) + sizeof(ENDORSED_DIR));
458 sprintf(buf, "%s" ENDORSED_DIR, Arguments::get_java_home());
459 Arguments::set_endorsed_dirs(buf);
460 }
461 }
463 #undef malloc
464 #undef getenv
465 #undef EXTENSIONS_DIR
466 #undef ENDORSED_DIR
468 // Done
469 return;
470 }
472 ////////////////////////////////////////////////////////////////////////////////
473 // breakpoint support
475 void os::breakpoint() {
476 BREAKPOINT;
477 }
479 extern "C" void breakpoint() {
480 // use debugger to set breakpoint here
481 }
483 ////////////////////////////////////////////////////////////////////////////////
484 // signal support
486 debug_only(static bool signal_sets_initialized = false);
487 static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs;
489 bool os::Linux::is_sig_ignored(int sig) {
490 struct sigaction oact;
491 sigaction(sig, (struct sigaction*)NULL, &oact);
492 void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*, oact.sa_sigaction)
493 : CAST_FROM_FN_PTR(void*, oact.sa_handler);
494 if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN))
495 return true;
496 else
497 return false;
498 }
500 void os::Linux::signal_sets_init() {
501 // Should also have an assertion stating we are still single-threaded.
502 assert(!signal_sets_initialized, "Already initialized");
503 // Fill in signals that are necessarily unblocked for all threads in
504 // the VM. Currently, we unblock the following signals:
505 // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden
506 // by -Xrs (=ReduceSignalUsage));
507 // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all
508 // other threads. The "ReduceSignalUsage" boolean tells us not to alter
509 // the dispositions or masks wrt these signals.
510 // Programs embedding the VM that want to use the above signals for their
511 // own purposes must, at this time, use the "-Xrs" option to prevent
512 // interference with shutdown hooks and BREAK_SIGNAL thread dumping.
513 // (See bug 4345157, and other related bugs).
514 // In reality, though, unblocking these signals is really a nop, since
515 // these signals are not blocked by default.
516 sigemptyset(&unblocked_sigs);
517 sigemptyset(&allowdebug_blocked_sigs);
518 sigaddset(&unblocked_sigs, SIGILL);
519 sigaddset(&unblocked_sigs, SIGSEGV);
520 sigaddset(&unblocked_sigs, SIGBUS);
521 sigaddset(&unblocked_sigs, SIGFPE);
522 sigaddset(&unblocked_sigs, SR_signum);
524 if (!ReduceSignalUsage) {
525 if (!os::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) {
526 sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL);
527 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL);
528 }
529 if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) {
530 sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL);
531 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL);
532 }
533 if (!os::Linux::is_sig_ignored(SHUTDOWN3_SIGNAL)) {
534 sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL);
535 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN3_SIGNAL);
536 }
537 }
538 // Fill in signals that are blocked by all but the VM thread.
539 sigemptyset(&vm_sigs);
540 if (!ReduceSignalUsage)
541 sigaddset(&vm_sigs, BREAK_SIGNAL);
542 debug_only(signal_sets_initialized = true);
544 }
546 // These are signals that are unblocked while a thread is running Java.
547 // (For some reason, they get blocked by default.)
548 sigset_t* os::Linux::unblocked_signals() {
549 assert(signal_sets_initialized, "Not initialized");
550 return &unblocked_sigs;
551 }
553 // These are the signals that are blocked while a (non-VM) thread is
554 // running Java. Only the VM thread handles these signals.
555 sigset_t* os::Linux::vm_signals() {
556 assert(signal_sets_initialized, "Not initialized");
557 return &vm_sigs;
558 }
560 // These are signals that are blocked during cond_wait to allow debugger in
561 sigset_t* os::Linux::allowdebug_blocked_signals() {
562 assert(signal_sets_initialized, "Not initialized");
563 return &allowdebug_blocked_sigs;
564 }
566 void os::Linux::hotspot_sigmask(Thread* thread) {
568 //Save caller's signal mask before setting VM signal mask
569 sigset_t caller_sigmask;
570 pthread_sigmask(SIG_BLOCK, NULL, &caller_sigmask);
572 OSThread* osthread = thread->osthread();
573 osthread->set_caller_sigmask(caller_sigmask);
575 pthread_sigmask(SIG_UNBLOCK, os::Linux::unblocked_signals(), NULL);
577 if (!ReduceSignalUsage) {
578 if (thread->is_VM_thread()) {
579 // Only the VM thread handles BREAK_SIGNAL ...
580 pthread_sigmask(SIG_UNBLOCK, vm_signals(), NULL);
581 } else {
582 // ... all other threads block BREAK_SIGNAL
583 pthread_sigmask(SIG_BLOCK, vm_signals(), NULL);
584 }
585 }
586 }
588 //////////////////////////////////////////////////////////////////////////////
589 // detecting pthread library
591 void os::Linux::libpthread_init() {
592 // Save glibc and pthread version strings. Note that _CS_GNU_LIBC_VERSION
593 // and _CS_GNU_LIBPTHREAD_VERSION are supported in glibc >= 2.3.2. Use a
594 // generic name for earlier versions.
595 // Define macros here so we can build HotSpot on old systems.
596 # ifndef _CS_GNU_LIBC_VERSION
597 # define _CS_GNU_LIBC_VERSION 2
598 # endif
599 # ifndef _CS_GNU_LIBPTHREAD_VERSION
600 # define _CS_GNU_LIBPTHREAD_VERSION 3
601 # endif
603 size_t n = confstr(_CS_GNU_LIBC_VERSION, NULL, 0);
604 if (n > 0) {
605 char *str = (char *)malloc(n, mtInternal);
606 confstr(_CS_GNU_LIBC_VERSION, str, n);
607 os::Linux::set_glibc_version(str);
608 } else {
609 // _CS_GNU_LIBC_VERSION is not supported, try gnu_get_libc_version()
610 static char _gnu_libc_version[32];
611 jio_snprintf(_gnu_libc_version, sizeof(_gnu_libc_version),
612 "glibc %s %s", gnu_get_libc_version(), gnu_get_libc_release());
613 os::Linux::set_glibc_version(_gnu_libc_version);
614 }
616 n = confstr(_CS_GNU_LIBPTHREAD_VERSION, NULL, 0);
617 if (n > 0) {
618 char *str = (char *)malloc(n, mtInternal);
619 confstr(_CS_GNU_LIBPTHREAD_VERSION, str, n);
620 // Vanilla RH-9 (glibc 2.3.2) has a bug that confstr() always tells
621 // us "NPTL-0.29" even we are running with LinuxThreads. Check if this
622 // is the case. LinuxThreads has a hard limit on max number of threads.
623 // So sysconf(_SC_THREAD_THREADS_MAX) will return a positive value.
624 // On the other hand, NPTL does not have such a limit, sysconf()
625 // will return -1 and errno is not changed. Check if it is really NPTL.
626 if (strcmp(os::Linux::glibc_version(), "glibc 2.3.2") == 0 &&
627 strstr(str, "NPTL") &&
628 sysconf(_SC_THREAD_THREADS_MAX) > 0) {
629 free(str);
630 os::Linux::set_libpthread_version("linuxthreads");
631 } else {
632 os::Linux::set_libpthread_version(str);
633 }
634 } else {
635 // glibc before 2.3.2 only has LinuxThreads.
636 os::Linux::set_libpthread_version("linuxthreads");
637 }
639 if (strstr(libpthread_version(), "NPTL")) {
640 os::Linux::set_is_NPTL();
641 } else {
642 os::Linux::set_is_LinuxThreads();
643 }
645 // LinuxThreads have two flavors: floating-stack mode, which allows variable
646 // stack size; and fixed-stack mode. NPTL is always floating-stack.
647 if (os::Linux::is_NPTL() || os::Linux::supports_variable_stack_size()) {
648 os::Linux::set_is_floating_stack();
649 }
650 }
652 /////////////////////////////////////////////////////////////////////////////
653 // thread stack
655 // Force Linux kernel to expand current thread stack. If "bottom" is close
656 // to the stack guard, caller should block all signals.
657 //
658 // MAP_GROWSDOWN:
659 // A special mmap() flag that is used to implement thread stacks. It tells
660 // kernel that the memory region should extend downwards when needed. This
661 // allows early versions of LinuxThreads to only mmap the first few pages
662 // when creating a new thread. Linux kernel will automatically expand thread
663 // stack as needed (on page faults).
664 //
665 // However, because the memory region of a MAP_GROWSDOWN stack can grow on
666 // demand, if a page fault happens outside an already mapped MAP_GROWSDOWN
667 // region, it's hard to tell if the fault is due to a legitimate stack
668 // access or because of reading/writing non-exist memory (e.g. buffer
669 // overrun). As a rule, if the fault happens below current stack pointer,
670 // Linux kernel does not expand stack, instead a SIGSEGV is sent to the
671 // application (see Linux kernel fault.c).
672 //
673 // This Linux feature can cause SIGSEGV when VM bangs thread stack for
674 // stack overflow detection.
675 //
676 // Newer version of LinuxThreads (since glibc-2.2, or, RH-7.x) and NPTL do
677 // not use this flag. However, the stack of initial thread is not created
678 // by pthread, it is still MAP_GROWSDOWN. Also it's possible (though
679 // unlikely) that user code can create a thread with MAP_GROWSDOWN stack
680 // and then attach the thread to JVM.
681 //
682 // To get around the problem and allow stack banging on Linux, we need to
683 // manually expand thread stack after receiving the SIGSEGV.
684 //
685 // There are two ways to expand thread stack to address "bottom", we used
686 // both of them in JVM before 1.5:
687 // 1. adjust stack pointer first so that it is below "bottom", and then
688 // touch "bottom"
689 // 2. mmap() the page in question
690 //
691 // Now alternate signal stack is gone, it's harder to use 2. For instance,
692 // if current sp is already near the lower end of page 101, and we need to
693 // call mmap() to map page 100, it is possible that part of the mmap() frame
694 // will be placed in page 100. When page 100 is mapped, it is zero-filled.
695 // That will destroy the mmap() frame and cause VM to crash.
696 //
697 // The following code works by adjusting sp first, then accessing the "bottom"
698 // page to force a page fault. Linux kernel will then automatically expand the
699 // stack mapping.
700 //
701 // _expand_stack_to() assumes its frame size is less than page size, which
702 // should always be true if the function is not inlined.
704 #if __GNUC__ < 3 // gcc 2.x does not support noinline attribute
705 #define NOINLINE
706 #else
707 #define NOINLINE __attribute__ ((noinline))
708 #endif
710 static void _expand_stack_to(address bottom) NOINLINE;
712 static void _expand_stack_to(address bottom) {
713 address sp;
714 size_t size;
715 volatile char *p;
717 // Adjust bottom to point to the largest address within the same page, it
718 // gives us a one-page buffer if alloca() allocates slightly more memory.
719 bottom = (address)align_size_down((uintptr_t)bottom, os::Linux::page_size());
720 bottom += os::Linux::page_size() - 1;
722 // sp might be slightly above current stack pointer; if that's the case, we
723 // will alloca() a little more space than necessary, which is OK. Don't use
724 // os::current_stack_pointer(), as its result can be slightly below current
725 // stack pointer, causing us to not alloca enough to reach "bottom".
726 sp = (address)&sp;
728 if (sp > bottom) {
729 size = sp - bottom;
730 p = (volatile char *)alloca(size);
731 assert(p != NULL && p <= (volatile char *)bottom, "alloca problem?");
732 p[0] = '\0';
733 }
734 }
736 bool os::Linux::manually_expand_stack(JavaThread * t, address addr) {
737 assert(t!=NULL, "just checking");
738 assert(t->osthread()->expanding_stack(), "expand should be set");
739 assert(t->stack_base() != NULL, "stack_base was not initialized");
741 if (addr < t->stack_base() && addr >= t->stack_yellow_zone_base()) {
742 sigset_t mask_all, old_sigset;
743 sigfillset(&mask_all);
744 pthread_sigmask(SIG_SETMASK, &mask_all, &old_sigset);
745 _expand_stack_to(addr);
746 pthread_sigmask(SIG_SETMASK, &old_sigset, NULL);
747 return true;
748 }
749 return false;
750 }
752 //////////////////////////////////////////////////////////////////////////////
753 // create new thread
755 static address highest_vm_reserved_address();
757 // check if it's safe to start a new thread
758 static bool _thread_safety_check(Thread* thread) {
759 if (os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack()) {
760 // Fixed stack LinuxThreads (SuSE Linux/x86, and some versions of Redhat)
761 // Heap is mmap'ed at lower end of memory space. Thread stacks are
762 // allocated (MAP_FIXED) from high address space. Every thread stack
763 // occupies a fixed size slot (usually 2Mbytes, but user can change
764 // it to other values if they rebuild LinuxThreads).
765 //
766 // Problem with MAP_FIXED is that mmap() can still succeed even part of
767 // the memory region has already been mmap'ed. That means if we have too
768 // many threads and/or very large heap, eventually thread stack will
769 // collide with heap.
770 //
771 // Here we try to prevent heap/stack collision by comparing current
772 // stack bottom with the highest address that has been mmap'ed by JVM
773 // plus a safety margin for memory maps created by native code.
774 //
775 // This feature can be disabled by setting ThreadSafetyMargin to 0
776 //
777 if (ThreadSafetyMargin > 0) {
778 address stack_bottom = os::current_stack_base() - os::current_stack_size();
780 // not safe if our stack extends below the safety margin
781 return stack_bottom - ThreadSafetyMargin >= highest_vm_reserved_address();
782 } else {
783 return true;
784 }
785 } else {
786 // Floating stack LinuxThreads or NPTL:
787 // Unlike fixed stack LinuxThreads, thread stacks are not MAP_FIXED. When
788 // there's not enough space left, pthread_create() will fail. If we come
789 // here, that means enough space has been reserved for stack.
790 return true;
791 }
792 }
794 // Thread start routine for all newly created threads
795 static void *java_start(Thread *thread) {
796 // Try to randomize the cache line index of hot stack frames.
797 // This helps when threads of the same stack traces evict each other's
798 // cache lines. The threads can be either from the same JVM instance, or
799 // from different JVM instances. The benefit is especially true for
800 // processors with hyperthreading technology.
801 static int counter = 0;
802 int pid = os::current_process_id();
803 alloca(((pid ^ counter++) & 7) * 128);
805 ThreadLocalStorage::set_thread(thread);
807 OSThread* osthread = thread->osthread();
808 Monitor* sync = osthread->startThread_lock();
810 // non floating stack LinuxThreads needs extra check, see above
811 if (!_thread_safety_check(thread)) {
812 // notify parent thread
813 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
814 osthread->set_state(ZOMBIE);
815 sync->notify_all();
816 return NULL;
817 }
819 // thread_id is kernel thread id (similar to Solaris LWP id)
820 osthread->set_thread_id(os::Linux::gettid());
822 if (UseNUMA) {
823 int lgrp_id = os::numa_get_group_id();
824 if (lgrp_id != -1) {
825 thread->set_lgrp_id(lgrp_id);
826 }
827 }
828 // initialize signal mask for this thread
829 os::Linux::hotspot_sigmask(thread);
831 // initialize floating point control register
832 os::Linux::init_thread_fpu_state();
834 // handshaking with parent thread
835 {
836 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
838 // notify parent thread
839 osthread->set_state(INITIALIZED);
840 sync->notify_all();
842 // wait until os::start_thread()
843 while (osthread->get_state() == INITIALIZED) {
844 sync->wait(Mutex::_no_safepoint_check_flag);
845 }
846 }
848 // call one more level start routine
849 thread->run();
851 return 0;
852 }
854 bool os::create_thread(Thread* thread, ThreadType thr_type, size_t stack_size) {
855 assert(thread->osthread() == NULL, "caller responsible");
857 // Allocate the OSThread object
858 OSThread* osthread = new OSThread(NULL, NULL);
859 if (osthread == NULL) {
860 return false;
861 }
863 // set the correct thread state
864 osthread->set_thread_type(thr_type);
866 // Initial state is ALLOCATED but not INITIALIZED
867 osthread->set_state(ALLOCATED);
869 thread->set_osthread(osthread);
871 // init thread attributes
872 pthread_attr_t attr;
873 pthread_attr_init(&attr);
874 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
876 // stack size
877 if (os::Linux::supports_variable_stack_size()) {
878 // calculate stack size if it's not specified by caller
879 if (stack_size == 0) {
880 stack_size = os::Linux::default_stack_size(thr_type);
882 switch (thr_type) {
883 case os::java_thread:
884 // Java threads use ThreadStackSize which default value can be
885 // changed with the flag -Xss
886 assert (JavaThread::stack_size_at_create() > 0, "this should be set");
887 stack_size = JavaThread::stack_size_at_create();
888 break;
889 case os::compiler_thread:
890 if (CompilerThreadStackSize > 0) {
891 stack_size = (size_t)(CompilerThreadStackSize * K);
892 break;
893 } // else fall through:
894 // use VMThreadStackSize if CompilerThreadStackSize is not defined
895 case os::vm_thread:
896 case os::pgc_thread:
897 case os::cgc_thread:
898 case os::watcher_thread:
899 if (VMThreadStackSize > 0) stack_size = (size_t)(VMThreadStackSize * K);
900 break;
901 }
902 }
904 stack_size = MAX2(stack_size, os::Linux::min_stack_allowed);
905 pthread_attr_setstacksize(&attr, stack_size);
906 } else {
907 // let pthread_create() pick the default value.
908 }
910 // glibc guard page
911 pthread_attr_setguardsize(&attr, os::Linux::default_guard_size(thr_type));
913 ThreadState state;
915 {
916 // Serialize thread creation if we are running with fixed stack LinuxThreads
917 bool lock = os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack();
918 if (lock) {
919 os::Linux::createThread_lock()->lock_without_safepoint_check();
920 }
922 pthread_t tid;
923 int ret = pthread_create(&tid, &attr, (void* (*)(void*)) java_start, thread);
925 pthread_attr_destroy(&attr);
927 if (ret != 0) {
928 if (PrintMiscellaneous && (Verbose || WizardMode)) {
929 perror("pthread_create()");
930 }
931 // Need to clean up stuff we've allocated so far
932 thread->set_osthread(NULL);
933 delete osthread;
934 if (lock) os::Linux::createThread_lock()->unlock();
935 return false;
936 }
938 // Store pthread info into the OSThread
939 osthread->set_pthread_id(tid);
941 // Wait until child thread is either initialized or aborted
942 {
943 Monitor* sync_with_child = osthread->startThread_lock();
944 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
945 while ((state = osthread->get_state()) == ALLOCATED) {
946 sync_with_child->wait(Mutex::_no_safepoint_check_flag);
947 }
948 }
950 if (lock) {
951 os::Linux::createThread_lock()->unlock();
952 }
953 }
955 // Aborted due to thread limit being reached
956 if (state == ZOMBIE) {
957 thread->set_osthread(NULL);
958 delete osthread;
959 return false;
960 }
962 // The thread is returned suspended (in state INITIALIZED),
963 // and is started higher up in the call chain
964 assert(state == INITIALIZED, "race condition");
965 return true;
966 }
968 /////////////////////////////////////////////////////////////////////////////
969 // attach existing thread
971 // bootstrap the main thread
972 bool os::create_main_thread(JavaThread* thread) {
973 assert(os::Linux::_main_thread == pthread_self(), "should be called inside main thread");
974 return create_attached_thread(thread);
975 }
977 bool os::create_attached_thread(JavaThread* thread) {
978 #ifdef ASSERT
979 thread->verify_not_published();
980 #endif
982 // Allocate the OSThread object
983 OSThread* osthread = new OSThread(NULL, NULL);
985 if (osthread == NULL) {
986 return false;
987 }
989 // Store pthread info into the OSThread
990 osthread->set_thread_id(os::Linux::gettid());
991 osthread->set_pthread_id(::pthread_self());
993 // initialize floating point control register
994 os::Linux::init_thread_fpu_state();
996 // Initial thread state is RUNNABLE
997 osthread->set_state(RUNNABLE);
999 thread->set_osthread(osthread);
1001 if (UseNUMA) {
1002 int lgrp_id = os::numa_get_group_id();
1003 if (lgrp_id != -1) {
1004 thread->set_lgrp_id(lgrp_id);
1005 }
1006 }
1008 if (os::Linux::is_initial_thread()) {
1009 // If current thread is initial thread, its stack is mapped on demand,
1010 // see notes about MAP_GROWSDOWN. Here we try to force kernel to map
1011 // the entire stack region to avoid SEGV in stack banging.
1012 // It is also useful to get around the heap-stack-gap problem on SuSE
1013 // kernel (see 4821821 for details). We first expand stack to the top
1014 // of yellow zone, then enable stack yellow zone (order is significant,
1015 // enabling yellow zone first will crash JVM on SuSE Linux), so there
1016 // is no gap between the last two virtual memory regions.
1018 JavaThread *jt = (JavaThread *)thread;
1019 address addr = jt->stack_yellow_zone_base();
1020 assert(addr != NULL, "initialization problem?");
1021 assert(jt->stack_available(addr) > 0, "stack guard should not be enabled");
1023 osthread->set_expanding_stack();
1024 os::Linux::manually_expand_stack(jt, addr);
1025 osthread->clear_expanding_stack();
1026 }
1028 // initialize signal mask for this thread
1029 // and save the caller's signal mask
1030 os::Linux::hotspot_sigmask(thread);
1032 return true;
1033 }
1035 void os::pd_start_thread(Thread* thread) {
1036 OSThread * osthread = thread->osthread();
1037 assert(osthread->get_state() != INITIALIZED, "just checking");
1038 Monitor* sync_with_child = osthread->startThread_lock();
1039 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
1040 sync_with_child->notify();
1041 }
1043 // Free Linux resources related to the OSThread
1044 void os::free_thread(OSThread* osthread) {
1045 assert(osthread != NULL, "osthread not set");
1047 if (Thread::current()->osthread() == osthread) {
1048 // Restore caller's signal mask
1049 sigset_t sigmask = osthread->caller_sigmask();
1050 pthread_sigmask(SIG_SETMASK, &sigmask, NULL);
1051 }
1053 delete osthread;
1054 }
1056 //////////////////////////////////////////////////////////////////////////////
1057 // thread local storage
1059 int os::allocate_thread_local_storage() {
1060 pthread_key_t key;
1061 int rslt = pthread_key_create(&key, NULL);
1062 assert(rslt == 0, "cannot allocate thread local storage");
1063 return (int)key;
1064 }
1066 // Note: This is currently not used by VM, as we don't destroy TLS key
1067 // on VM exit.
1068 void os::free_thread_local_storage(int index) {
1069 int rslt = pthread_key_delete((pthread_key_t)index);
1070 assert(rslt == 0, "invalid index");
1071 }
1073 void os::thread_local_storage_at_put(int index, void* value) {
1074 int rslt = pthread_setspecific((pthread_key_t)index, value);
1075 assert(rslt == 0, "pthread_setspecific failed");
1076 }
1078 extern "C" Thread* get_thread() {
1079 return ThreadLocalStorage::thread();
1080 }
1082 //////////////////////////////////////////////////////////////////////////////
1083 // initial thread
1085 // Check if current thread is the initial thread, similar to Solaris thr_main.
1086 bool os::Linux::is_initial_thread(void) {
1087 char dummy;
1088 // If called before init complete, thread stack bottom will be null.
1089 // Can be called if fatal error occurs before initialization.
1090 if (initial_thread_stack_bottom() == NULL) return false;
1091 assert(initial_thread_stack_bottom() != NULL &&
1092 initial_thread_stack_size() != 0,
1093 "os::init did not locate initial thread's stack region");
1094 if ((address)&dummy >= initial_thread_stack_bottom() &&
1095 (address)&dummy < initial_thread_stack_bottom() + initial_thread_stack_size())
1096 return true;
1097 else return false;
1098 }
1100 // Find the virtual memory area that contains addr
1101 static bool find_vma(address addr, address* vma_low, address* vma_high) {
1102 FILE *fp = fopen("/proc/self/maps", "r");
1103 if (fp) {
1104 address low, high;
1105 while (!feof(fp)) {
1106 if (fscanf(fp, "%p-%p", &low, &high) == 2) {
1107 if (low <= addr && addr < high) {
1108 if (vma_low) *vma_low = low;
1109 if (vma_high) *vma_high = high;
1110 fclose (fp);
1111 return true;
1112 }
1113 }
1114 for (;;) {
1115 int ch = fgetc(fp);
1116 if (ch == EOF || ch == (int)'\n') break;
1117 }
1118 }
1119 fclose(fp);
1120 }
1121 return false;
1122 }
1124 // Locate initial thread stack. This special handling of initial thread stack
1125 // is needed because pthread_getattr_np() on most (all?) Linux distros returns
1126 // bogus value for initial thread.
1127 void os::Linux::capture_initial_stack(size_t max_size) {
1128 // stack size is the easy part, get it from RLIMIT_STACK
1129 size_t stack_size;
1130 struct rlimit rlim;
1131 getrlimit(RLIMIT_STACK, &rlim);
1132 stack_size = rlim.rlim_cur;
1134 // 6308388: a bug in ld.so will relocate its own .data section to the
1135 // lower end of primordial stack; reduce ulimit -s value a little bit
1136 // so we won't install guard page on ld.so's data section.
1137 stack_size -= 2 * page_size();
1139 // 4441425: avoid crash with "unlimited" stack size on SuSE 7.1 or Redhat
1140 // 7.1, in both cases we will get 2G in return value.
1141 // 4466587: glibc 2.2.x compiled w/o "--enable-kernel=2.4.0" (RH 7.0,
1142 // SuSE 7.2, Debian) can not handle alternate signal stack correctly
1143 // for initial thread if its stack size exceeds 6M. Cap it at 2M,
1144 // in case other parts in glibc still assumes 2M max stack size.
1145 // FIXME: alt signal stack is gone, maybe we can relax this constraint?
1146 // Problem still exists RH7.2 (IA64 anyway) but 2MB is a little small
1147 if (stack_size > 2 * K * K IA64_ONLY(*2))
1148 stack_size = 2 * K * K IA64_ONLY(*2);
1149 // Try to figure out where the stack base (top) is. This is harder.
1150 //
1151 // When an application is started, glibc saves the initial stack pointer in
1152 // a global variable "__libc_stack_end", which is then used by system
1153 // libraries. __libc_stack_end should be pretty close to stack top. The
1154 // variable is available since the very early days. However, because it is
1155 // a private interface, it could disappear in the future.
1156 //
1157 // Linux kernel saves start_stack information in /proc/<pid>/stat. Similar
1158 // to __libc_stack_end, it is very close to stack top, but isn't the real
1159 // stack top. Note that /proc may not exist if VM is running as a chroot
1160 // program, so reading /proc/<pid>/stat could fail. Also the contents of
1161 // /proc/<pid>/stat could change in the future (though unlikely).
1162 //
1163 // We try __libc_stack_end first. If that doesn't work, look for
1164 // /proc/<pid>/stat. If neither of them works, we use current stack pointer
1165 // as a hint, which should work well in most cases.
1167 uintptr_t stack_start;
1169 // try __libc_stack_end first
1170 uintptr_t *p = (uintptr_t *)dlsym(RTLD_DEFAULT, "__libc_stack_end");
1171 if (p && *p) {
1172 stack_start = *p;
1173 } else {
1174 // see if we can get the start_stack field from /proc/self/stat
1175 FILE *fp;
1176 int pid;
1177 char state;
1178 int ppid;
1179 int pgrp;
1180 int session;
1181 int nr;
1182 int tpgrp;
1183 unsigned long flags;
1184 unsigned long minflt;
1185 unsigned long cminflt;
1186 unsigned long majflt;
1187 unsigned long cmajflt;
1188 unsigned long utime;
1189 unsigned long stime;
1190 long cutime;
1191 long cstime;
1192 long prio;
1193 long nice;
1194 long junk;
1195 long it_real;
1196 uintptr_t start;
1197 uintptr_t vsize;
1198 intptr_t rss;
1199 uintptr_t rsslim;
1200 uintptr_t scodes;
1201 uintptr_t ecode;
1202 int i;
1204 // Figure what the primordial thread stack base is. Code is inspired
1205 // by email from Hans Boehm. /proc/self/stat begins with current pid,
1206 // followed by command name surrounded by parentheses, state, etc.
1207 char stat[2048];
1208 int statlen;
1210 fp = fopen("/proc/self/stat", "r");
1211 if (fp) {
1212 statlen = fread(stat, 1, 2047, fp);
1213 stat[statlen] = '\0';
1214 fclose(fp);
1216 // Skip pid and the command string. Note that we could be dealing with
1217 // weird command names, e.g. user could decide to rename java launcher
1218 // to "java 1.4.2 :)", then the stat file would look like
1219 // 1234 (java 1.4.2 :)) R ... ...
1220 // We don't really need to know the command string, just find the last
1221 // occurrence of ")" and then start parsing from there. See bug 4726580.
1222 char * s = strrchr(stat, ')');
1224 i = 0;
1225 if (s) {
1226 // Skip blank chars
1227 do s++; while (isspace(*s));
1229 #define _UFM UINTX_FORMAT
1230 #define _DFM INTX_FORMAT
1232 /* 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 */
1233 /* 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 */
1234 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,
1235 &state, /* 3 %c */
1236 &ppid, /* 4 %d */
1237 &pgrp, /* 5 %d */
1238 &session, /* 6 %d */
1239 &nr, /* 7 %d */
1240 &tpgrp, /* 8 %d */
1241 &flags, /* 9 %lu */
1242 &minflt, /* 10 %lu */
1243 &cminflt, /* 11 %lu */
1244 &majflt, /* 12 %lu */
1245 &cmajflt, /* 13 %lu */
1246 &utime, /* 14 %lu */
1247 &stime, /* 15 %lu */
1248 &cutime, /* 16 %ld */
1249 &cstime, /* 17 %ld */
1250 &prio, /* 18 %ld */
1251 &nice, /* 19 %ld */
1252 &junk, /* 20 %ld */
1253 &it_real, /* 21 %ld */
1254 &start, /* 22 UINTX_FORMAT */
1255 &vsize, /* 23 UINTX_FORMAT */
1256 &rss, /* 24 INTX_FORMAT */
1257 &rsslim, /* 25 UINTX_FORMAT */
1258 &scodes, /* 26 UINTX_FORMAT */
1259 &ecode, /* 27 UINTX_FORMAT */
1260 &stack_start); /* 28 UINTX_FORMAT */
1261 }
1263 #undef _UFM
1264 #undef _DFM
1266 if (i != 28 - 2) {
1267 assert(false, "Bad conversion from /proc/self/stat");
1268 // product mode - assume we are the initial thread, good luck in the
1269 // embedded case.
1270 warning("Can't detect initial thread stack location - bad conversion");
1271 stack_start = (uintptr_t) &rlim;
1272 }
1273 } else {
1274 // For some reason we can't open /proc/self/stat (for example, running on
1275 // FreeBSD with a Linux emulator, or inside chroot), this should work for
1276 // most cases, so don't abort:
1277 warning("Can't detect initial thread stack location - no /proc/self/stat");
1278 stack_start = (uintptr_t) &rlim;
1279 }
1280 }
1282 // Now we have a pointer (stack_start) very close to the stack top, the
1283 // next thing to do is to figure out the exact location of stack top. We
1284 // can find out the virtual memory area that contains stack_start by
1285 // reading /proc/self/maps, it should be the last vma in /proc/self/maps,
1286 // and its upper limit is the real stack top. (again, this would fail if
1287 // running inside chroot, because /proc may not exist.)
1289 uintptr_t stack_top;
1290 address low, high;
1291 if (find_vma((address)stack_start, &low, &high)) {
1292 // success, "high" is the true stack top. (ignore "low", because initial
1293 // thread stack grows on demand, its real bottom is high - RLIMIT_STACK.)
1294 stack_top = (uintptr_t)high;
1295 } else {
1296 // failed, likely because /proc/self/maps does not exist
1297 warning("Can't detect initial thread stack location - find_vma failed");
1298 // best effort: stack_start is normally within a few pages below the real
1299 // stack top, use it as stack top, and reduce stack size so we won't put
1300 // guard page outside stack.
1301 stack_top = stack_start;
1302 stack_size -= 16 * page_size();
1303 }
1305 // stack_top could be partially down the page so align it
1306 stack_top = align_size_up(stack_top, page_size());
1308 if (max_size && stack_size > max_size) {
1309 _initial_thread_stack_size = max_size;
1310 } else {
1311 _initial_thread_stack_size = stack_size;
1312 }
1314 _initial_thread_stack_size = align_size_down(_initial_thread_stack_size, page_size());
1315 _initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size;
1316 }
1318 ////////////////////////////////////////////////////////////////////////////////
1319 // time support
1321 // Time since start-up in seconds to a fine granularity.
1322 // Used by VMSelfDestructTimer and the MemProfiler.
1323 double os::elapsedTime() {
1325 return (double)(os::elapsed_counter()) * 0.000001;
1326 }
1328 jlong os::elapsed_counter() {
1329 timeval time;
1330 int status = gettimeofday(&time, NULL);
1331 return jlong(time.tv_sec) * 1000 * 1000 + jlong(time.tv_usec) - initial_time_count;
1332 }
1334 jlong os::elapsed_frequency() {
1335 return (1000 * 1000);
1336 }
1338 // For now, we say that linux does not support vtime. I have no idea
1339 // whether it can actually be made to (DLD, 9/13/05).
1341 bool os::supports_vtime() { return false; }
1342 bool os::enable_vtime() { return false; }
1343 bool os::vtime_enabled() { return false; }
1344 double os::elapsedVTime() {
1345 // better than nothing, but not much
1346 return elapsedTime();
1347 }
1349 jlong os::javaTimeMillis() {
1350 timeval time;
1351 int status = gettimeofday(&time, NULL);
1352 assert(status != -1, "linux error");
1353 return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000);
1354 }
1356 #ifndef CLOCK_MONOTONIC
1357 #define CLOCK_MONOTONIC (1)
1358 #endif
1360 void os::Linux::clock_init() {
1361 // we do dlopen's in this particular order due to bug in linux
1362 // dynamical loader (see 6348968) leading to crash on exit
1363 void* handle = dlopen("librt.so.1", RTLD_LAZY);
1364 if (handle == NULL) {
1365 handle = dlopen("librt.so", RTLD_LAZY);
1366 }
1368 if (handle) {
1369 int (*clock_getres_func)(clockid_t, struct timespec*) =
1370 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres");
1371 int (*clock_gettime_func)(clockid_t, struct timespec*) =
1372 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime");
1373 if (clock_getres_func && clock_gettime_func) {
1374 // See if monotonic clock is supported by the kernel. Note that some
1375 // early implementations simply return kernel jiffies (updated every
1376 // 1/100 or 1/1000 second). It would be bad to use such a low res clock
1377 // for nano time (though the monotonic property is still nice to have).
1378 // It's fixed in newer kernels, however clock_getres() still returns
1379 // 1/HZ. We check if clock_getres() works, but will ignore its reported
1380 // resolution for now. Hopefully as people move to new kernels, this
1381 // won't be a problem.
1382 struct timespec res;
1383 struct timespec tp;
1384 if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 &&
1385 clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) {
1386 // yes, monotonic clock is supported
1387 _clock_gettime = clock_gettime_func;
1388 } else {
1389 // close librt if there is no monotonic clock
1390 dlclose(handle);
1391 }
1392 }
1393 }
1394 }
1396 #ifndef SYS_clock_getres
1398 #if defined(IA32) || defined(AMD64)
1399 #define SYS_clock_getres IA32_ONLY(266) AMD64_ONLY(229)
1400 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y)
1401 #else
1402 #warning "SYS_clock_getres not defined for this platform, disabling fast_thread_cpu_time"
1403 #define sys_clock_getres(x,y) -1
1404 #endif
1406 #else
1407 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y)
1408 #endif
1410 void os::Linux::fast_thread_clock_init() {
1411 if (!UseLinuxPosixThreadCPUClocks) {
1412 return;
1413 }
1414 clockid_t clockid;
1415 struct timespec tp;
1416 int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) =
1417 (int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid");
1419 // Switch to using fast clocks for thread cpu time if
1420 // the sys_clock_getres() returns 0 error code.
1421 // Note, that some kernels may support the current thread
1422 // clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks
1423 // returned by the pthread_getcpuclockid().
1424 // If the fast Posix clocks are supported then the sys_clock_getres()
1425 // must return at least tp.tv_sec == 0 which means a resolution
1426 // better than 1 sec. This is extra check for reliability.
1428 if(pthread_getcpuclockid_func &&
1429 pthread_getcpuclockid_func(_main_thread, &clockid) == 0 &&
1430 sys_clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) {
1432 _supports_fast_thread_cpu_time = true;
1433 _pthread_getcpuclockid = pthread_getcpuclockid_func;
1434 }
1435 }
1437 jlong os::javaTimeNanos() {
1438 if (Linux::supports_monotonic_clock()) {
1439 struct timespec tp;
1440 int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp);
1441 assert(status == 0, "gettime error");
1442 jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec);
1443 return result;
1444 } else {
1445 timeval time;
1446 int status = gettimeofday(&time, NULL);
1447 assert(status != -1, "linux error");
1448 jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec);
1449 return 1000 * usecs;
1450 }
1451 }
1453 void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) {
1454 if (Linux::supports_monotonic_clock()) {
1455 info_ptr->max_value = ALL_64_BITS;
1457 // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past
1458 info_ptr->may_skip_backward = false; // not subject to resetting or drifting
1459 info_ptr->may_skip_forward = false; // not subject to resetting or drifting
1460 } else {
1461 // gettimeofday - based on time in seconds since the Epoch thus does not wrap
1462 info_ptr->max_value = ALL_64_BITS;
1464 // gettimeofday is a real time clock so it skips
1465 info_ptr->may_skip_backward = true;
1466 info_ptr->may_skip_forward = true;
1467 }
1469 info_ptr->kind = JVMTI_TIMER_ELAPSED; // elapsed not CPU time
1470 }
1472 // Return the real, user, and system times in seconds from an
1473 // arbitrary fixed point in the past.
1474 bool os::getTimesSecs(double* process_real_time,
1475 double* process_user_time,
1476 double* process_system_time) {
1477 struct tms ticks;
1478 clock_t real_ticks = times(&ticks);
1480 if (real_ticks == (clock_t) (-1)) {
1481 return false;
1482 } else {
1483 double ticks_per_second = (double) clock_tics_per_sec;
1484 *process_user_time = ((double) ticks.tms_utime) / ticks_per_second;
1485 *process_system_time = ((double) ticks.tms_stime) / ticks_per_second;
1486 *process_real_time = ((double) real_ticks) / ticks_per_second;
1488 return true;
1489 }
1490 }
1493 char * os::local_time_string(char *buf, size_t buflen) {
1494 struct tm t;
1495 time_t long_time;
1496 time(&long_time);
1497 localtime_r(&long_time, &t);
1498 jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d",
1499 t.tm_year + 1900, t.tm_mon + 1, t.tm_mday,
1500 t.tm_hour, t.tm_min, t.tm_sec);
1501 return buf;
1502 }
1504 struct tm* os::localtime_pd(const time_t* clock, struct tm* res) {
1505 return localtime_r(clock, res);
1506 }
1508 ////////////////////////////////////////////////////////////////////////////////
1509 // runtime exit support
1511 // Note: os::shutdown() might be called very early during initialization, or
1512 // called from signal handler. Before adding something to os::shutdown(), make
1513 // sure it is async-safe and can handle partially initialized VM.
1514 void os::shutdown() {
1516 // allow PerfMemory to attempt cleanup of any persistent resources
1517 perfMemory_exit();
1519 // needs to remove object in file system
1520 AttachListener::abort();
1522 // flush buffered output, finish log files
1523 ostream_abort();
1525 // Check for abort hook
1526 abort_hook_t abort_hook = Arguments::abort_hook();
1527 if (abort_hook != NULL) {
1528 abort_hook();
1529 }
1531 }
1533 // Note: os::abort() might be called very early during initialization, or
1534 // called from signal handler. Before adding something to os::abort(), make
1535 // sure it is async-safe and can handle partially initialized VM.
1536 void os::abort(bool dump_core) {
1537 os::shutdown();
1538 if (dump_core) {
1539 #ifndef PRODUCT
1540 fdStream out(defaultStream::output_fd());
1541 out.print_raw("Current thread is ");
1542 char buf[16];
1543 jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id());
1544 out.print_raw_cr(buf);
1545 out.print_raw_cr("Dumping core ...");
1546 #endif
1547 ::abort(); // dump core
1548 }
1550 ::exit(1);
1551 }
1553 // Die immediately, no exit hook, no abort hook, no cleanup.
1554 void os::die() {
1555 // _exit() on LinuxThreads only kills current thread
1556 ::abort();
1557 }
1559 // unused on linux for now.
1560 void os::set_error_file(const char *logfile) {}
1563 // This method is a copy of JDK's sysGetLastErrorString
1564 // from src/solaris/hpi/src/system_md.c
1566 size_t os::lasterror(char *buf, size_t len) {
1568 if (errno == 0) return 0;
1570 const char *s = ::strerror(errno);
1571 size_t n = ::strlen(s);
1572 if (n >= len) {
1573 n = len - 1;
1574 }
1575 ::strncpy(buf, s, n);
1576 buf[n] = '\0';
1577 return n;
1578 }
1580 intx os::current_thread_id() { return (intx)pthread_self(); }
1581 int os::current_process_id() {
1583 // Under the old linux thread library, linux gives each thread
1584 // its own process id. Because of this each thread will return
1585 // a different pid if this method were to return the result
1586 // of getpid(2). Linux provides no api that returns the pid
1587 // of the launcher thread for the vm. This implementation
1588 // returns a unique pid, the pid of the launcher thread
1589 // that starts the vm 'process'.
1591 // Under the NPTL, getpid() returns the same pid as the
1592 // launcher thread rather than a unique pid per thread.
1593 // Use gettid() if you want the old pre NPTL behaviour.
1595 // if you are looking for the result of a call to getpid() that
1596 // returns a unique pid for the calling thread, then look at the
1597 // OSThread::thread_id() method in osThread_linux.hpp file
1599 return (int)(_initial_pid ? _initial_pid : getpid());
1600 }
1602 // DLL functions
1604 const char* os::dll_file_extension() { return ".so"; }
1606 // This must be hard coded because it's the system's temporary
1607 // directory not the java application's temp directory, ala java.io.tmpdir.
1608 const char* os::get_temp_directory() { return "/tmp"; }
1610 static bool file_exists(const char* filename) {
1611 struct stat statbuf;
1612 if (filename == NULL || strlen(filename) == 0) {
1613 return false;
1614 }
1615 return os::stat(filename, &statbuf) == 0;
1616 }
1618 bool os::dll_build_name(char* buffer, size_t buflen,
1619 const char* pname, const char* fname) {
1620 bool retval = false;
1621 // Copied from libhpi
1622 const size_t pnamelen = pname ? strlen(pname) : 0;
1624 // Return error on buffer overflow.
1625 if (pnamelen + strlen(fname) + 10 > (size_t) buflen) {
1626 return retval;
1627 }
1629 if (pnamelen == 0) {
1630 snprintf(buffer, buflen, "lib%s.so", fname);
1631 retval = true;
1632 } else if (strchr(pname, *os::path_separator()) != NULL) {
1633 int n;
1634 char** pelements = split_path(pname, &n);
1635 if (pelements == NULL) {
1636 return false;
1637 }
1638 for (int i = 0 ; i < n ; i++) {
1639 // Really shouldn't be NULL, but check can't hurt
1640 if (pelements[i] == NULL || strlen(pelements[i]) == 0) {
1641 continue; // skip the empty path values
1642 }
1643 snprintf(buffer, buflen, "%s/lib%s.so", pelements[i], fname);
1644 if (file_exists(buffer)) {
1645 retval = true;
1646 break;
1647 }
1648 }
1649 // release the storage
1650 for (int i = 0 ; i < n ; i++) {
1651 if (pelements[i] != NULL) {
1652 FREE_C_HEAP_ARRAY(char, pelements[i], mtInternal);
1653 }
1654 }
1655 if (pelements != NULL) {
1656 FREE_C_HEAP_ARRAY(char*, pelements, mtInternal);
1657 }
1658 } else {
1659 snprintf(buffer, buflen, "%s/lib%s.so", pname, fname);
1660 retval = true;
1661 }
1662 return retval;
1663 }
1665 // check if addr is inside libjvm.so
1666 bool os::address_is_in_vm(address addr) {
1667 static address libjvm_base_addr;
1668 Dl_info dlinfo;
1670 if (libjvm_base_addr == NULL) {
1671 dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo);
1672 libjvm_base_addr = (address)dlinfo.dli_fbase;
1673 assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm");
1674 }
1676 if (dladdr((void *)addr, &dlinfo)) {
1677 if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true;
1678 }
1680 return false;
1681 }
1683 bool os::dll_address_to_function_name(address addr, char *buf,
1684 int buflen, int *offset) {
1685 Dl_info dlinfo;
1687 if (dladdr((void*)addr, &dlinfo) && dlinfo.dli_sname != NULL) {
1688 if (buf != NULL) {
1689 if(!Decoder::demangle(dlinfo.dli_sname, buf, buflen)) {
1690 jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname);
1691 }
1692 }
1693 if (offset != NULL) *offset = addr - (address)dlinfo.dli_saddr;
1694 return true;
1695 } else if (dlinfo.dli_fname != NULL && dlinfo.dli_fbase != 0) {
1696 if (Decoder::decode((address)(addr - (address)dlinfo.dli_fbase),
1697 buf, buflen, offset, dlinfo.dli_fname)) {
1698 return true;
1699 }
1700 }
1702 if (buf != NULL) buf[0] = '\0';
1703 if (offset != NULL) *offset = -1;
1704 return false;
1705 }
1707 struct _address_to_library_name {
1708 address addr; // input : memory address
1709 size_t buflen; // size of fname
1710 char* fname; // output: library name
1711 address base; // library base addr
1712 };
1714 static int address_to_library_name_callback(struct dl_phdr_info *info,
1715 size_t size, void *data) {
1716 int i;
1717 bool found = false;
1718 address libbase = NULL;
1719 struct _address_to_library_name * d = (struct _address_to_library_name *)data;
1721 // iterate through all loadable segments
1722 for (i = 0; i < info->dlpi_phnum; i++) {
1723 address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr);
1724 if (info->dlpi_phdr[i].p_type == PT_LOAD) {
1725 // base address of a library is the lowest address of its loaded
1726 // segments.
1727 if (libbase == NULL || libbase > segbase) {
1728 libbase = segbase;
1729 }
1730 // see if 'addr' is within current segment
1731 if (segbase <= d->addr &&
1732 d->addr < segbase + info->dlpi_phdr[i].p_memsz) {
1733 found = true;
1734 }
1735 }
1736 }
1738 // dlpi_name is NULL or empty if the ELF file is executable, return 0
1739 // so dll_address_to_library_name() can fall through to use dladdr() which
1740 // can figure out executable name from argv[0].
1741 if (found && info->dlpi_name && info->dlpi_name[0]) {
1742 d->base = libbase;
1743 if (d->fname) {
1744 jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name);
1745 }
1746 return 1;
1747 }
1748 return 0;
1749 }
1751 bool os::dll_address_to_library_name(address addr, char* buf,
1752 int buflen, int* offset) {
1753 Dl_info dlinfo;
1754 struct _address_to_library_name data;
1756 // There is a bug in old glibc dladdr() implementation that it could resolve
1757 // to wrong library name if the .so file has a base address != NULL. Here
1758 // we iterate through the program headers of all loaded libraries to find
1759 // out which library 'addr' really belongs to. This workaround can be
1760 // removed once the minimum requirement for glibc is moved to 2.3.x.
1761 data.addr = addr;
1762 data.fname = buf;
1763 data.buflen = buflen;
1764 data.base = NULL;
1765 int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data);
1767 if (rslt) {
1768 // buf already contains library name
1769 if (offset) *offset = addr - data.base;
1770 return true;
1771 } else if (dladdr((void*)addr, &dlinfo)){
1772 if (buf) jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname);
1773 if (offset) *offset = addr - (address)dlinfo.dli_fbase;
1774 return true;
1775 } else {
1776 if (buf) buf[0] = '\0';
1777 if (offset) *offset = -1;
1778 return false;
1779 }
1780 }
1782 // Loads .dll/.so and
1783 // in case of error it checks if .dll/.so was built for the
1784 // same architecture as Hotspot is running on
1787 // Remember the stack's state. The Linux dynamic linker will change
1788 // the stack to 'executable' at most once, so we must safepoint only once.
1789 bool os::Linux::_stack_is_executable = false;
1791 // VM operation that loads a library. This is necessary if stack protection
1792 // of the Java stacks can be lost during loading the library. If we
1793 // do not stop the Java threads, they can stack overflow before the stacks
1794 // are protected again.
1795 class VM_LinuxDllLoad: public VM_Operation {
1796 private:
1797 const char *_filename;
1798 char *_ebuf;
1799 int _ebuflen;
1800 void *_lib;
1801 public:
1802 VM_LinuxDllLoad(const char *fn, char *ebuf, int ebuflen) :
1803 _filename(fn), _ebuf(ebuf), _ebuflen(ebuflen), _lib(NULL) {}
1804 VMOp_Type type() const { return VMOp_LinuxDllLoad; }
1805 void doit() {
1806 _lib = os::Linux::dll_load_in_vmthread(_filename, _ebuf, _ebuflen);
1807 os::Linux::_stack_is_executable = true;
1808 }
1809 void* loaded_library() { return _lib; }
1810 };
1812 void * os::dll_load(const char *filename, char *ebuf, int ebuflen)
1813 {
1814 void * result = NULL;
1815 bool load_attempted = false;
1817 // Check whether the library to load might change execution rights
1818 // of the stack. If they are changed, the protection of the stack
1819 // guard pages will be lost. We need a safepoint to fix this.
1820 //
1821 // See Linux man page execstack(8) for more info.
1822 if (os::uses_stack_guard_pages() && !os::Linux::_stack_is_executable) {
1823 ElfFile ef(filename);
1824 if (!ef.specifies_noexecstack()) {
1825 if (!is_init_completed()) {
1826 os::Linux::_stack_is_executable = true;
1827 // This is OK - No Java threads have been created yet, and hence no
1828 // stack guard pages to fix.
1829 //
1830 // This should happen only when you are building JDK7 using a very
1831 // old version of JDK6 (e.g., with JPRT) and running test_gamma.
1832 //
1833 // Dynamic loader will make all stacks executable after
1834 // this function returns, and will not do that again.
1835 assert(Threads::first() == NULL, "no Java threads should exist yet.");
1836 } else {
1837 warning("You have loaded library %s which might have disabled stack guard. "
1838 "The VM will try to fix the stack guard now.\n"
1839 "It's highly recommended that you fix the library with "
1840 "'execstack -c <libfile>', or link it with '-z noexecstack'.",
1841 filename);
1843 assert(Thread::current()->is_Java_thread(), "must be Java thread");
1844 JavaThread *jt = JavaThread::current();
1845 if (jt->thread_state() != _thread_in_native) {
1846 // This happens when a compiler thread tries to load a hsdis-<arch>.so file
1847 // that requires ExecStack. Cannot enter safe point. Let's give up.
1848 warning("Unable to fix stack guard. Giving up.");
1849 } else {
1850 if (!LoadExecStackDllInVMThread) {
1851 // This is for the case where the DLL has an static
1852 // constructor function that executes JNI code. We cannot
1853 // load such DLLs in the VMThread.
1854 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen);
1855 }
1857 ThreadInVMfromNative tiv(jt);
1858 debug_only(VMNativeEntryWrapper vew;)
1860 VM_LinuxDllLoad op(filename, ebuf, ebuflen);
1861 VMThread::execute(&op);
1862 if (LoadExecStackDllInVMThread) {
1863 result = op.loaded_library();
1864 }
1865 load_attempted = true;
1866 }
1867 }
1868 }
1869 }
1871 if (!load_attempted) {
1872 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen);
1873 }
1875 if (result != NULL) {
1876 // Successful loading
1877 return result;
1878 }
1880 Elf32_Ehdr elf_head;
1881 int diag_msg_max_length=ebuflen-strlen(ebuf);
1882 char* diag_msg_buf=ebuf+strlen(ebuf);
1884 if (diag_msg_max_length==0) {
1885 // No more space in ebuf for additional diagnostics message
1886 return NULL;
1887 }
1890 int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK);
1892 if (file_descriptor < 0) {
1893 // Can't open library, report dlerror() message
1894 return NULL;
1895 }
1897 bool failed_to_read_elf_head=
1898 (sizeof(elf_head)!=
1899 (::read(file_descriptor, &elf_head,sizeof(elf_head)))) ;
1901 ::close(file_descriptor);
1902 if (failed_to_read_elf_head) {
1903 // file i/o error - report dlerror() msg
1904 return NULL;
1905 }
1907 typedef struct {
1908 Elf32_Half code; // Actual value as defined in elf.h
1909 Elf32_Half compat_class; // Compatibility of archs at VM's sense
1910 char elf_class; // 32 or 64 bit
1911 char endianess; // MSB or LSB
1912 char* name; // String representation
1913 } arch_t;
1915 #ifndef EM_486
1916 #define EM_486 6 /* Intel 80486 */
1917 #endif
1919 static const arch_t arch_array[]={
1920 {EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
1921 {EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
1922 {EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"},
1923 {EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"},
1924 {EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
1925 {EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
1926 {EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"},
1927 {EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"},
1928 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"},
1929 {EM_ARM, EM_ARM, ELFCLASS32, ELFDATA2LSB, (char*)"ARM"},
1930 {EM_S390, EM_S390, ELFCLASSNONE, ELFDATA2MSB, (char*)"IBM System/390"},
1931 {EM_ALPHA, EM_ALPHA, ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"},
1932 {EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"},
1933 {EM_MIPS, EM_MIPS, ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"},
1934 {EM_PARISC, EM_PARISC, ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"},
1935 {EM_68K, EM_68K, ELFCLASS32, ELFDATA2MSB, (char*)"M68k"}
1936 };
1938 #if (defined IA32)
1939 static Elf32_Half running_arch_code=EM_386;
1940 #elif (defined AMD64)
1941 static Elf32_Half running_arch_code=EM_X86_64;
1942 #elif (defined IA64)
1943 static Elf32_Half running_arch_code=EM_IA_64;
1944 #elif (defined __sparc) && (defined _LP64)
1945 static Elf32_Half running_arch_code=EM_SPARCV9;
1946 #elif (defined __sparc) && (!defined _LP64)
1947 static Elf32_Half running_arch_code=EM_SPARC;
1948 #elif (defined __powerpc64__)
1949 static Elf32_Half running_arch_code=EM_PPC64;
1950 #elif (defined __powerpc__)
1951 static Elf32_Half running_arch_code=EM_PPC;
1952 #elif (defined ARM)
1953 static Elf32_Half running_arch_code=EM_ARM;
1954 #elif (defined S390)
1955 static Elf32_Half running_arch_code=EM_S390;
1956 #elif (defined ALPHA)
1957 static Elf32_Half running_arch_code=EM_ALPHA;
1958 #elif (defined MIPSEL)
1959 static Elf32_Half running_arch_code=EM_MIPS_RS3_LE;
1960 #elif (defined PARISC)
1961 static Elf32_Half running_arch_code=EM_PARISC;
1962 #elif (defined MIPS)
1963 static Elf32_Half running_arch_code=EM_MIPS;
1964 #elif (defined M68K)
1965 static Elf32_Half running_arch_code=EM_68K;
1966 #else
1967 #error Method os::dll_load requires that one of following is defined:\
1968 IA32, AMD64, IA64, __sparc, __powerpc__, ARM, S390, ALPHA, MIPS, MIPSEL, PARISC, M68K
1969 #endif
1971 // Identify compatability class for VM's architecture and library's architecture
1972 // Obtain string descriptions for architectures
1974 arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL};
1975 int running_arch_index=-1;
1977 for (unsigned int i=0 ; i < ARRAY_SIZE(arch_array) ; i++ ) {
1978 if (running_arch_code == arch_array[i].code) {
1979 running_arch_index = i;
1980 }
1981 if (lib_arch.code == arch_array[i].code) {
1982 lib_arch.compat_class = arch_array[i].compat_class;
1983 lib_arch.name = arch_array[i].name;
1984 }
1985 }
1987 assert(running_arch_index != -1,
1988 "Didn't find running architecture code (running_arch_code) in arch_array");
1989 if (running_arch_index == -1) {
1990 // Even though running architecture detection failed
1991 // we may still continue with reporting dlerror() message
1992 return NULL;
1993 }
1995 if (lib_arch.endianess != arch_array[running_arch_index].endianess) {
1996 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)");
1997 return NULL;
1998 }
2000 #ifndef S390
2001 if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) {
2002 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)");
2003 return NULL;
2004 }
2005 #endif // !S390
2007 if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) {
2008 if ( lib_arch.name!=NULL ) {
2009 ::snprintf(diag_msg_buf, diag_msg_max_length-1,
2010 " (Possible cause: can't load %s-bit .so on a %s-bit platform)",
2011 lib_arch.name, arch_array[running_arch_index].name);
2012 } else {
2013 ::snprintf(diag_msg_buf, diag_msg_max_length-1,
2014 " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)",
2015 lib_arch.code,
2016 arch_array[running_arch_index].name);
2017 }
2018 }
2020 return NULL;
2021 }
2023 void * os::Linux::dlopen_helper(const char *filename, char *ebuf, int ebuflen) {
2024 void * result = ::dlopen(filename, RTLD_LAZY);
2025 if (result == NULL) {
2026 ::strncpy(ebuf, ::dlerror(), ebuflen - 1);
2027 ebuf[ebuflen-1] = '\0';
2028 }
2029 return result;
2030 }
2032 void * os::Linux::dll_load_in_vmthread(const char *filename, char *ebuf, int ebuflen) {
2033 void * result = NULL;
2034 if (LoadExecStackDllInVMThread) {
2035 result = dlopen_helper(filename, ebuf, ebuflen);
2036 }
2038 // Since 7019808, libjvm.so is linked with -noexecstack. If the VM loads a
2039 // library that requires an executable stack, or which does not have this
2040 // stack attribute set, dlopen changes the stack attribute to executable. The
2041 // read protection of the guard pages gets lost.
2042 //
2043 // Need to check _stack_is_executable again as multiple VM_LinuxDllLoad
2044 // may have been queued at the same time.
2046 if (!_stack_is_executable) {
2047 JavaThread *jt = Threads::first();
2049 while (jt) {
2050 if (!jt->stack_guard_zone_unused() && // Stack not yet fully initialized
2051 jt->stack_yellow_zone_enabled()) { // No pending stack overflow exceptions
2052 if (!os::guard_memory((char *) jt->stack_red_zone_base() - jt->stack_red_zone_size(),
2053 jt->stack_yellow_zone_size() + jt->stack_red_zone_size())) {
2054 warning("Attempt to reguard stack yellow zone failed.");
2055 }
2056 }
2057 jt = jt->next();
2058 }
2059 }
2061 return result;
2062 }
2064 /*
2065 * glibc-2.0 libdl is not MT safe. If you are building with any glibc,
2066 * chances are you might want to run the generated bits against glibc-2.0
2067 * libdl.so, so always use locking for any version of glibc.
2068 */
2069 void* os::dll_lookup(void* handle, const char* name) {
2070 pthread_mutex_lock(&dl_mutex);
2071 void* res = dlsym(handle, name);
2072 pthread_mutex_unlock(&dl_mutex);
2073 return res;
2074 }
2077 static bool _print_ascii_file(const char* filename, outputStream* st) {
2078 int fd = ::open(filename, O_RDONLY);
2079 if (fd == -1) {
2080 return false;
2081 }
2083 char buf[32];
2084 int bytes;
2085 while ((bytes = ::read(fd, buf, sizeof(buf))) > 0) {
2086 st->print_raw(buf, bytes);
2087 }
2089 ::close(fd);
2091 return true;
2092 }
2094 void os::print_dll_info(outputStream *st) {
2095 st->print_cr("Dynamic libraries:");
2097 char fname[32];
2098 pid_t pid = os::Linux::gettid();
2100 jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid);
2102 if (!_print_ascii_file(fname, st)) {
2103 st->print("Can not get library information for pid = %d\n", pid);
2104 }
2105 }
2107 void os::print_os_info_brief(outputStream* st) {
2108 os::Linux::print_distro_info(st);
2110 os::Posix::print_uname_info(st);
2112 os::Linux::print_libversion_info(st);
2114 }
2116 void os::print_os_info(outputStream* st) {
2117 st->print("OS:");
2119 os::Linux::print_distro_info(st);
2121 os::Posix::print_uname_info(st);
2123 // Print warning if unsafe chroot environment detected
2124 if (unsafe_chroot_detected) {
2125 st->print("WARNING!! ");
2126 st->print_cr(unstable_chroot_error);
2127 }
2129 os::Linux::print_libversion_info(st);
2131 os::Posix::print_rlimit_info(st);
2133 os::Posix::print_load_average(st);
2135 os::Linux::print_full_memory_info(st);
2136 }
2138 // Try to identify popular distros.
2139 // Most Linux distributions have /etc/XXX-release file, which contains
2140 // the OS version string. Some have more than one /etc/XXX-release file
2141 // (e.g. Mandrake has both /etc/mandrake-release and /etc/redhat-release.),
2142 // so the order is important.
2143 void os::Linux::print_distro_info(outputStream* st) {
2144 if (!_print_ascii_file("/etc/mandrake-release", st) &&
2145 !_print_ascii_file("/etc/sun-release", st) &&
2146 !_print_ascii_file("/etc/redhat-release", st) &&
2147 !_print_ascii_file("/etc/SuSE-release", st) &&
2148 !_print_ascii_file("/etc/turbolinux-release", st) &&
2149 !_print_ascii_file("/etc/gentoo-release", st) &&
2150 !_print_ascii_file("/etc/debian_version", st) &&
2151 !_print_ascii_file("/etc/ltib-release", st) &&
2152 !_print_ascii_file("/etc/angstrom-version", st)) {
2153 st->print("Linux");
2154 }
2155 st->cr();
2156 }
2158 void os::Linux::print_libversion_info(outputStream* st) {
2159 // libc, pthread
2160 st->print("libc:");
2161 st->print(os::Linux::glibc_version()); st->print(" ");
2162 st->print(os::Linux::libpthread_version()); st->print(" ");
2163 if (os::Linux::is_LinuxThreads()) {
2164 st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed");
2165 }
2166 st->cr();
2167 }
2169 void os::Linux::print_full_memory_info(outputStream* st) {
2170 st->print("\n/proc/meminfo:\n");
2171 _print_ascii_file("/proc/meminfo", st);
2172 st->cr();
2173 }
2175 void os::print_memory_info(outputStream* st) {
2177 st->print("Memory:");
2178 st->print(" %dk page", os::vm_page_size()>>10);
2180 // values in struct sysinfo are "unsigned long"
2181 struct sysinfo si;
2182 sysinfo(&si);
2184 st->print(", physical " UINT64_FORMAT "k",
2185 os::physical_memory() >> 10);
2186 st->print("(" UINT64_FORMAT "k free)",
2187 os::available_memory() >> 10);
2188 st->print(", swap " UINT64_FORMAT "k",
2189 ((jlong)si.totalswap * si.mem_unit) >> 10);
2190 st->print("(" UINT64_FORMAT "k free)",
2191 ((jlong)si.freeswap * si.mem_unit) >> 10);
2192 st->cr();
2193 }
2195 void os::pd_print_cpu_info(outputStream* st) {
2196 st->print("\n/proc/cpuinfo:\n");
2197 if (!_print_ascii_file("/proc/cpuinfo", st)) {
2198 st->print(" <Not Available>");
2199 }
2200 st->cr();
2201 }
2203 // Taken from /usr/include/bits/siginfo.h Supposed to be architecture specific
2204 // but they're the same for all the linux arch that we support
2205 // and they're the same for solaris but there's no common place to put this.
2206 const char *ill_names[] = { "ILL0", "ILL_ILLOPC", "ILL_ILLOPN", "ILL_ILLADR",
2207 "ILL_ILLTRP", "ILL_PRVOPC", "ILL_PRVREG",
2208 "ILL_COPROC", "ILL_BADSTK" };
2210 const char *fpe_names[] = { "FPE0", "FPE_INTDIV", "FPE_INTOVF", "FPE_FLTDIV",
2211 "FPE_FLTOVF", "FPE_FLTUND", "FPE_FLTRES",
2212 "FPE_FLTINV", "FPE_FLTSUB", "FPE_FLTDEN" };
2214 const char *segv_names[] = { "SEGV0", "SEGV_MAPERR", "SEGV_ACCERR" };
2216 const char *bus_names[] = { "BUS0", "BUS_ADRALN", "BUS_ADRERR", "BUS_OBJERR" };
2218 void os::print_siginfo(outputStream* st, void* siginfo) {
2219 st->print("siginfo:");
2221 const int buflen = 100;
2222 char buf[buflen];
2223 siginfo_t *si = (siginfo_t*)siginfo;
2224 st->print("si_signo=%s: ", os::exception_name(si->si_signo, buf, buflen));
2225 if (si->si_errno != 0 && strerror_r(si->si_errno, buf, buflen) == 0) {
2226 st->print("si_errno=%s", buf);
2227 } else {
2228 st->print("si_errno=%d", si->si_errno);
2229 }
2230 const int c = si->si_code;
2231 assert(c > 0, "unexpected si_code");
2232 switch (si->si_signo) {
2233 case SIGILL:
2234 st->print(", si_code=%d (%s)", c, c > 8 ? "" : ill_names[c]);
2235 st->print(", si_addr=" PTR_FORMAT, si->si_addr);
2236 break;
2237 case SIGFPE:
2238 st->print(", si_code=%d (%s)", c, c > 9 ? "" : fpe_names[c]);
2239 st->print(", si_addr=" PTR_FORMAT, si->si_addr);
2240 break;
2241 case SIGSEGV:
2242 st->print(", si_code=%d (%s)", c, c > 2 ? "" : segv_names[c]);
2243 st->print(", si_addr=" PTR_FORMAT, si->si_addr);
2244 break;
2245 case SIGBUS:
2246 st->print(", si_code=%d (%s)", c, c > 3 ? "" : bus_names[c]);
2247 st->print(", si_addr=" PTR_FORMAT, si->si_addr);
2248 break;
2249 default:
2250 st->print(", si_code=%d", si->si_code);
2251 // no si_addr
2252 }
2254 if ((si->si_signo == SIGBUS || si->si_signo == SIGSEGV) &&
2255 UseSharedSpaces) {
2256 FileMapInfo* mapinfo = FileMapInfo::current_info();
2257 if (mapinfo->is_in_shared_space(si->si_addr)) {
2258 st->print("\n\nError accessing class data sharing archive." \
2259 " Mapped file inaccessible during execution, " \
2260 " possible disk/network problem.");
2261 }
2262 }
2263 st->cr();
2264 }
2267 static void print_signal_handler(outputStream* st, int sig,
2268 char* buf, size_t buflen);
2270 void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) {
2271 st->print_cr("Signal Handlers:");
2272 print_signal_handler(st, SIGSEGV, buf, buflen);
2273 print_signal_handler(st, SIGBUS , buf, buflen);
2274 print_signal_handler(st, SIGFPE , buf, buflen);
2275 print_signal_handler(st, SIGPIPE, buf, buflen);
2276 print_signal_handler(st, SIGXFSZ, buf, buflen);
2277 print_signal_handler(st, SIGILL , buf, buflen);
2278 print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen);
2279 print_signal_handler(st, SR_signum, buf, buflen);
2280 print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen);
2281 print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen);
2282 print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen);
2283 print_signal_handler(st, BREAK_SIGNAL, buf, buflen);
2284 }
2286 static char saved_jvm_path[MAXPATHLEN] = {0};
2288 // Find the full path to the current module, libjvm.so
2289 void os::jvm_path(char *buf, jint buflen) {
2290 // Error checking.
2291 if (buflen < MAXPATHLEN) {
2292 assert(false, "must use a large-enough buffer");
2293 buf[0] = '\0';
2294 return;
2295 }
2296 // Lazy resolve the path to current module.
2297 if (saved_jvm_path[0] != 0) {
2298 strcpy(buf, saved_jvm_path);
2299 return;
2300 }
2302 char dli_fname[MAXPATHLEN];
2303 bool ret = dll_address_to_library_name(
2304 CAST_FROM_FN_PTR(address, os::jvm_path),
2305 dli_fname, sizeof(dli_fname), NULL);
2306 assert(ret != 0, "cannot locate libjvm");
2307 char *rp = realpath(dli_fname, buf);
2308 if (rp == NULL)
2309 return;
2311 if (Arguments::created_by_gamma_launcher()) {
2312 // Support for the gamma launcher. Typical value for buf is
2313 // "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so". If "/jre/lib/" appears at
2314 // the right place in the string, then assume we are installed in a JDK and
2315 // we're done. Otherwise, check for a JAVA_HOME environment variable and fix
2316 // up the path so it looks like libjvm.so is installed there (append a
2317 // fake suffix hotspot/libjvm.so).
2318 const char *p = buf + strlen(buf) - 1;
2319 for (int count = 0; p > buf && count < 5; ++count) {
2320 for (--p; p > buf && *p != '/'; --p)
2321 /* empty */ ;
2322 }
2324 if (strncmp(p, "/jre/lib/", 9) != 0) {
2325 // Look for JAVA_HOME in the environment.
2326 char* java_home_var = ::getenv("JAVA_HOME");
2327 if (java_home_var != NULL && java_home_var[0] != 0) {
2328 char* jrelib_p;
2329 int len;
2331 // Check the current module name "libjvm.so".
2332 p = strrchr(buf, '/');
2333 assert(strstr(p, "/libjvm") == p, "invalid library name");
2335 rp = realpath(java_home_var, buf);
2336 if (rp == NULL)
2337 return;
2339 // determine if this is a legacy image or modules image
2340 // modules image doesn't have "jre" subdirectory
2341 len = strlen(buf);
2342 jrelib_p = buf + len;
2343 snprintf(jrelib_p, buflen-len, "/jre/lib/%s", cpu_arch);
2344 if (0 != access(buf, F_OK)) {
2345 snprintf(jrelib_p, buflen-len, "/lib/%s", cpu_arch);
2346 }
2348 if (0 == access(buf, F_OK)) {
2349 // Use current module name "libjvm.so"
2350 len = strlen(buf);
2351 snprintf(buf + len, buflen-len, "/hotspot/libjvm.so");
2352 } else {
2353 // Go back to path of .so
2354 rp = realpath(dli_fname, buf);
2355 if (rp == NULL)
2356 return;
2357 }
2358 }
2359 }
2360 }
2362 strcpy(saved_jvm_path, buf);
2363 }
2365 void os::print_jni_name_prefix_on(outputStream* st, int args_size) {
2366 // no prefix required, not even "_"
2367 }
2369 void os::print_jni_name_suffix_on(outputStream* st, int args_size) {
2370 // no suffix required
2371 }
2373 ////////////////////////////////////////////////////////////////////////////////
2374 // sun.misc.Signal support
2376 static volatile jint sigint_count = 0;
2378 static void
2379 UserHandler(int sig, void *siginfo, void *context) {
2380 // 4511530 - sem_post is serialized and handled by the manager thread. When
2381 // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We
2382 // don't want to flood the manager thread with sem_post requests.
2383 if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1)
2384 return;
2386 // Ctrl-C is pressed during error reporting, likely because the error
2387 // handler fails to abort. Let VM die immediately.
2388 if (sig == SIGINT && is_error_reported()) {
2389 os::die();
2390 }
2392 os::signal_notify(sig);
2393 }
2395 void* os::user_handler() {
2396 return CAST_FROM_FN_PTR(void*, UserHandler);
2397 }
2399 extern "C" {
2400 typedef void (*sa_handler_t)(int);
2401 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *);
2402 }
2404 void* os::signal(int signal_number, void* handler) {
2405 struct sigaction sigAct, oldSigAct;
2407 sigfillset(&(sigAct.sa_mask));
2408 sigAct.sa_flags = SA_RESTART|SA_SIGINFO;
2409 sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler);
2411 if (sigaction(signal_number, &sigAct, &oldSigAct)) {
2412 // -1 means registration failed
2413 return (void *)-1;
2414 }
2416 return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler);
2417 }
2419 void os::signal_raise(int signal_number) {
2420 ::raise(signal_number);
2421 }
2423 /*
2424 * The following code is moved from os.cpp for making this
2425 * code platform specific, which it is by its very nature.
2426 */
2428 // Will be modified when max signal is changed to be dynamic
2429 int os::sigexitnum_pd() {
2430 return NSIG;
2431 }
2433 // a counter for each possible signal value
2434 static volatile jint pending_signals[NSIG+1] = { 0 };
2436 // Linux(POSIX) specific hand shaking semaphore.
2437 static sem_t sig_sem;
2439 void os::signal_init_pd() {
2440 // Initialize signal structures
2441 ::memset((void*)pending_signals, 0, sizeof(pending_signals));
2443 // Initialize signal semaphore
2444 ::sem_init(&sig_sem, 0, 0);
2445 }
2447 void os::signal_notify(int sig) {
2448 Atomic::inc(&pending_signals[sig]);
2449 ::sem_post(&sig_sem);
2450 }
2452 static int check_pending_signals(bool wait) {
2453 Atomic::store(0, &sigint_count);
2454 for (;;) {
2455 for (int i = 0; i < NSIG + 1; i++) {
2456 jint n = pending_signals[i];
2457 if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) {
2458 return i;
2459 }
2460 }
2461 if (!wait) {
2462 return -1;
2463 }
2464 JavaThread *thread = JavaThread::current();
2465 ThreadBlockInVM tbivm(thread);
2467 bool threadIsSuspended;
2468 do {
2469 thread->set_suspend_equivalent();
2470 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
2471 ::sem_wait(&sig_sem);
2473 // were we externally suspended while we were waiting?
2474 threadIsSuspended = thread->handle_special_suspend_equivalent_condition();
2475 if (threadIsSuspended) {
2476 //
2477 // The semaphore has been incremented, but while we were waiting
2478 // another thread suspended us. We don't want to continue running
2479 // while suspended because that would surprise the thread that
2480 // suspended us.
2481 //
2482 ::sem_post(&sig_sem);
2484 thread->java_suspend_self();
2485 }
2486 } while (threadIsSuspended);
2487 }
2488 }
2490 int os::signal_lookup() {
2491 return check_pending_signals(false);
2492 }
2494 int os::signal_wait() {
2495 return check_pending_signals(true);
2496 }
2498 ////////////////////////////////////////////////////////////////////////////////
2499 // Virtual Memory
2501 int os::vm_page_size() {
2502 // Seems redundant as all get out
2503 assert(os::Linux::page_size() != -1, "must call os::init");
2504 return os::Linux::page_size();
2505 }
2507 // Solaris allocates memory by pages.
2508 int os::vm_allocation_granularity() {
2509 assert(os::Linux::page_size() != -1, "must call os::init");
2510 return os::Linux::page_size();
2511 }
2513 // Rationale behind this function:
2514 // current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable
2515 // mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get
2516 // samples for JITted code. Here we create private executable mapping over the code cache
2517 // and then we can use standard (well, almost, as mapping can change) way to provide
2518 // info for the reporting script by storing timestamp and location of symbol
2519 void linux_wrap_code(char* base, size_t size) {
2520 static volatile jint cnt = 0;
2522 if (!UseOprofile) {
2523 return;
2524 }
2526 char buf[PATH_MAX+1];
2527 int num = Atomic::add(1, &cnt);
2529 snprintf(buf, sizeof(buf), "%s/hs-vm-%d-%d",
2530 os::get_temp_directory(), os::current_process_id(), num);
2531 unlink(buf);
2533 int fd = ::open(buf, O_CREAT | O_RDWR, S_IRWXU);
2535 if (fd != -1) {
2536 off_t rv = ::lseek(fd, size-2, SEEK_SET);
2537 if (rv != (off_t)-1) {
2538 if (::write(fd, "", 1) == 1) {
2539 mmap(base, size,
2540 PROT_READ|PROT_WRITE|PROT_EXEC,
2541 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0);
2542 }
2543 }
2544 ::close(fd);
2545 unlink(buf);
2546 }
2547 }
2549 // NOTE: Linux kernel does not really reserve the pages for us.
2550 // All it does is to check if there are enough free pages
2551 // left at the time of mmap(). This could be a potential
2552 // problem.
2553 bool os::pd_commit_memory(char* addr, size_t size, bool exec) {
2554 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
2555 uintptr_t res = (uintptr_t) ::mmap(addr, size, prot,
2556 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0);
2557 if (res != (uintptr_t) MAP_FAILED) {
2558 if (UseNUMAInterleaving) {
2559 numa_make_global(addr, size);
2560 }
2561 return true;
2562 }
2563 return false;
2564 }
2566 // Define MAP_HUGETLB here so we can build HotSpot on old systems.
2567 #ifndef MAP_HUGETLB
2568 #define MAP_HUGETLB 0x40000
2569 #endif
2571 // Define MADV_HUGEPAGE here so we can build HotSpot on old systems.
2572 #ifndef MADV_HUGEPAGE
2573 #define MADV_HUGEPAGE 14
2574 #endif
2576 bool os::pd_commit_memory(char* addr, size_t size, size_t alignment_hint,
2577 bool exec) {
2578 if (UseHugeTLBFS && alignment_hint > (size_t)vm_page_size()) {
2579 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
2580 uintptr_t res =
2581 (uintptr_t) ::mmap(addr, size, prot,
2582 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS|MAP_HUGETLB,
2583 -1, 0);
2584 if (res != (uintptr_t) MAP_FAILED) {
2585 if (UseNUMAInterleaving) {
2586 numa_make_global(addr, size);
2587 }
2588 return true;
2589 }
2590 // Fall through and try to use small pages
2591 }
2593 if (commit_memory(addr, size, exec)) {
2594 realign_memory(addr, size, alignment_hint);
2595 return true;
2596 }
2597 return false;
2598 }
2600 void os::pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint) {
2601 if (UseHugeTLBFS && alignment_hint > (size_t)vm_page_size()) {
2602 // We don't check the return value: madvise(MADV_HUGEPAGE) may not
2603 // be supported or the memory may already be backed by huge pages.
2604 ::madvise(addr, bytes, MADV_HUGEPAGE);
2605 }
2606 }
2608 void os::pd_free_memory(char *addr, size_t bytes, size_t alignment_hint) {
2609 // This method works by doing an mmap over an existing mmaping and effectively discarding
2610 // the existing pages. However it won't work for SHM-based large pages that cannot be
2611 // uncommitted at all. We don't do anything in this case to avoid creating a segment with
2612 // small pages on top of the SHM segment. This method always works for small pages, so we
2613 // allow that in any case.
2614 if (alignment_hint <= (size_t)os::vm_page_size() || !UseSHM) {
2615 commit_memory(addr, bytes, alignment_hint, false);
2616 }
2617 }
2619 void os::numa_make_global(char *addr, size_t bytes) {
2620 Linux::numa_interleave_memory(addr, bytes);
2621 }
2623 void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) {
2624 Linux::numa_tonode_memory(addr, bytes, lgrp_hint);
2625 }
2627 bool os::numa_topology_changed() { return false; }
2629 size_t os::numa_get_groups_num() {
2630 int max_node = Linux::numa_max_node();
2631 return max_node > 0 ? max_node + 1 : 1;
2632 }
2634 int os::numa_get_group_id() {
2635 int cpu_id = Linux::sched_getcpu();
2636 if (cpu_id != -1) {
2637 int lgrp_id = Linux::get_node_by_cpu(cpu_id);
2638 if (lgrp_id != -1) {
2639 return lgrp_id;
2640 }
2641 }
2642 return 0;
2643 }
2645 size_t os::numa_get_leaf_groups(int *ids, size_t size) {
2646 for (size_t i = 0; i < size; i++) {
2647 ids[i] = i;
2648 }
2649 return size;
2650 }
2652 bool os::get_page_info(char *start, page_info* info) {
2653 return false;
2654 }
2656 char *os::scan_pages(char *start, char* end, page_info* page_expected, page_info* page_found) {
2657 return end;
2658 }
2661 int os::Linux::sched_getcpu_syscall(void) {
2662 unsigned int cpu;
2663 int retval = -1;
2665 #if defined(IA32)
2666 # ifndef SYS_getcpu
2667 # define SYS_getcpu 318
2668 # endif
2669 retval = syscall(SYS_getcpu, &cpu, NULL, NULL);
2670 #elif defined(AMD64)
2671 // Unfortunately we have to bring all these macros here from vsyscall.h
2672 // to be able to compile on old linuxes.
2673 # define __NR_vgetcpu 2
2674 # define VSYSCALL_START (-10UL << 20)
2675 # define VSYSCALL_SIZE 1024
2676 # define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr))
2677 typedef long (*vgetcpu_t)(unsigned int *cpu, unsigned int *node, unsigned long *tcache);
2678 vgetcpu_t vgetcpu = (vgetcpu_t)VSYSCALL_ADDR(__NR_vgetcpu);
2679 retval = vgetcpu(&cpu, NULL, NULL);
2680 #endif
2682 return (retval == -1) ? retval : cpu;
2683 }
2685 // Something to do with the numa-aware allocator needs these symbols
2686 extern "C" JNIEXPORT void numa_warn(int number, char *where, ...) { }
2687 extern "C" JNIEXPORT void numa_error(char *where) { }
2688 extern "C" JNIEXPORT int fork1() { return fork(); }
2691 // If we are running with libnuma version > 2, then we should
2692 // be trying to use symbols with versions 1.1
2693 // If we are running with earlier version, which did not have symbol versions,
2694 // we should use the base version.
2695 void* os::Linux::libnuma_dlsym(void* handle, const char *name) {
2696 void *f = dlvsym(handle, name, "libnuma_1.1");
2697 if (f == NULL) {
2698 f = dlsym(handle, name);
2699 }
2700 return f;
2701 }
2703 bool os::Linux::libnuma_init() {
2704 // sched_getcpu() should be in libc.
2705 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t,
2706 dlsym(RTLD_DEFAULT, "sched_getcpu")));
2708 // If it's not, try a direct syscall.
2709 if (sched_getcpu() == -1)
2710 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, (void*)&sched_getcpu_syscall));
2712 if (sched_getcpu() != -1) { // Does it work?
2713 void *handle = dlopen("libnuma.so.1", RTLD_LAZY);
2714 if (handle != NULL) {
2715 set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t,
2716 libnuma_dlsym(handle, "numa_node_to_cpus")));
2717 set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t,
2718 libnuma_dlsym(handle, "numa_max_node")));
2719 set_numa_available(CAST_TO_FN_PTR(numa_available_func_t,
2720 libnuma_dlsym(handle, "numa_available")));
2721 set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t,
2722 libnuma_dlsym(handle, "numa_tonode_memory")));
2723 set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t,
2724 libnuma_dlsym(handle, "numa_interleave_memory")));
2727 if (numa_available() != -1) {
2728 set_numa_all_nodes((unsigned long*)libnuma_dlsym(handle, "numa_all_nodes"));
2729 // Create a cpu -> node mapping
2730 _cpu_to_node = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<int>(0, true);
2731 rebuild_cpu_to_node_map();
2732 return true;
2733 }
2734 }
2735 }
2736 return false;
2737 }
2739 // rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id.
2740 // The table is later used in get_node_by_cpu().
2741 void os::Linux::rebuild_cpu_to_node_map() {
2742 const size_t NCPUS = 32768; // Since the buffer size computation is very obscure
2743 // in libnuma (possible values are starting from 16,
2744 // and continuing up with every other power of 2, but less
2745 // than the maximum number of CPUs supported by kernel), and
2746 // is a subject to change (in libnuma version 2 the requirements
2747 // are more reasonable) we'll just hardcode the number they use
2748 // in the library.
2749 const size_t BitsPerCLong = sizeof(long) * CHAR_BIT;
2751 size_t cpu_num = os::active_processor_count();
2752 size_t cpu_map_size = NCPUS / BitsPerCLong;
2753 size_t cpu_map_valid_size =
2754 MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size);
2756 cpu_to_node()->clear();
2757 cpu_to_node()->at_grow(cpu_num - 1);
2758 size_t node_num = numa_get_groups_num();
2760 unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size, mtInternal);
2761 for (size_t i = 0; i < node_num; i++) {
2762 if (numa_node_to_cpus(i, cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) {
2763 for (size_t j = 0; j < cpu_map_valid_size; j++) {
2764 if (cpu_map[j] != 0) {
2765 for (size_t k = 0; k < BitsPerCLong; k++) {
2766 if (cpu_map[j] & (1UL << k)) {
2767 cpu_to_node()->at_put(j * BitsPerCLong + k, i);
2768 }
2769 }
2770 }
2771 }
2772 }
2773 }
2774 FREE_C_HEAP_ARRAY(unsigned long, cpu_map, mtInternal);
2775 }
2777 int os::Linux::get_node_by_cpu(int cpu_id) {
2778 if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) {
2779 return cpu_to_node()->at(cpu_id);
2780 }
2781 return -1;
2782 }
2784 GrowableArray<int>* os::Linux::_cpu_to_node;
2785 os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu;
2786 os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus;
2787 os::Linux::numa_max_node_func_t os::Linux::_numa_max_node;
2788 os::Linux::numa_available_func_t os::Linux::_numa_available;
2789 os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory;
2790 os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory;
2791 unsigned long* os::Linux::_numa_all_nodes;
2793 bool os::pd_uncommit_memory(char* addr, size_t size) {
2794 uintptr_t res = (uintptr_t) ::mmap(addr, size, PROT_NONE,
2795 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0);
2796 return res != (uintptr_t) MAP_FAILED;
2797 }
2799 // Linux uses a growable mapping for the stack, and if the mapping for
2800 // the stack guard pages is not removed when we detach a thread the
2801 // stack cannot grow beyond the pages where the stack guard was
2802 // mapped. If at some point later in the process the stack expands to
2803 // that point, the Linux kernel cannot expand the stack any further
2804 // because the guard pages are in the way, and a segfault occurs.
2805 //
2806 // However, it's essential not to split the stack region by unmapping
2807 // a region (leaving a hole) that's already part of the stack mapping,
2808 // so if the stack mapping has already grown beyond the guard pages at
2809 // the time we create them, we have to truncate the stack mapping.
2810 // So, we need to know the extent of the stack mapping when
2811 // create_stack_guard_pages() is called.
2813 // Find the bounds of the stack mapping. Return true for success.
2814 //
2815 // We only need this for stacks that are growable: at the time of
2816 // writing thread stacks don't use growable mappings (i.e. those
2817 // creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this
2818 // only applies to the main thread.
2820 static
2821 bool get_stack_bounds(uintptr_t *bottom, uintptr_t *top) {
2823 char buf[128];
2824 int fd, sz;
2826 if ((fd = ::open("/proc/self/maps", O_RDONLY)) < 0) {
2827 return false;
2828 }
2830 const char kw[] = "[stack]";
2831 const int kwlen = sizeof(kw)-1;
2833 // Address part of /proc/self/maps couldn't be more than 128 bytes
2834 while ((sz = os::get_line_chars(fd, buf, sizeof(buf))) > 0) {
2835 if (sz > kwlen && ::memcmp(buf+sz-kwlen, kw, kwlen) == 0) {
2836 // Extract addresses
2837 if (sscanf(buf, "%" SCNxPTR "-%" SCNxPTR, bottom, top) == 2) {
2838 uintptr_t sp = (uintptr_t) __builtin_frame_address(0);
2839 if (sp >= *bottom && sp <= *top) {
2840 ::close(fd);
2841 return true;
2842 }
2843 }
2844 }
2845 }
2847 ::close(fd);
2848 return false;
2849 }
2852 // If the (growable) stack mapping already extends beyond the point
2853 // where we're going to put our guard pages, truncate the mapping at
2854 // that point by munmap()ping it. This ensures that when we later
2855 // munmap() the guard pages we don't leave a hole in the stack
2856 // mapping. This only affects the main/initial thread, but guard
2857 // against future OS changes
2858 bool os::pd_create_stack_guard_pages(char* addr, size_t size) {
2859 uintptr_t stack_extent, stack_base;
2860 bool chk_bounds = NOT_DEBUG(os::Linux::is_initial_thread()) DEBUG_ONLY(true);
2861 if (chk_bounds && get_stack_bounds(&stack_extent, &stack_base)) {
2862 assert(os::Linux::is_initial_thread(),
2863 "growable stack in non-initial thread");
2864 if (stack_extent < (uintptr_t)addr)
2865 ::munmap((void*)stack_extent, (uintptr_t)addr - stack_extent);
2866 }
2868 return os::commit_memory(addr, size);
2869 }
2871 // If this is a growable mapping, remove the guard pages entirely by
2872 // munmap()ping them. If not, just call uncommit_memory(). This only
2873 // affects the main/initial thread, but guard against future OS changes
2874 bool os::remove_stack_guard_pages(char* addr, size_t size) {
2875 uintptr_t stack_extent, stack_base;
2876 bool chk_bounds = NOT_DEBUG(os::Linux::is_initial_thread()) DEBUG_ONLY(true);
2877 if (chk_bounds && get_stack_bounds(&stack_extent, &stack_base)) {
2878 assert(os::Linux::is_initial_thread(),
2879 "growable stack in non-initial thread");
2881 return ::munmap(addr, size) == 0;
2882 }
2884 return os::uncommit_memory(addr, size);
2885 }
2887 static address _highest_vm_reserved_address = NULL;
2889 // If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory
2890 // at 'requested_addr'. If there are existing memory mappings at the same
2891 // location, however, they will be overwritten. If 'fixed' is false,
2892 // 'requested_addr' is only treated as a hint, the return value may or
2893 // may not start from the requested address. Unlike Linux mmap(), this
2894 // function returns NULL to indicate failure.
2895 static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) {
2896 char * addr;
2897 int flags;
2899 flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS;
2900 if (fixed) {
2901 assert((uintptr_t)requested_addr % os::Linux::page_size() == 0, "unaligned address");
2902 flags |= MAP_FIXED;
2903 }
2905 // Map uncommitted pages PROT_READ and PROT_WRITE, change access
2906 // to PROT_EXEC if executable when we commit the page.
2907 addr = (char*)::mmap(requested_addr, bytes, PROT_READ|PROT_WRITE,
2908 flags, -1, 0);
2910 if (addr != MAP_FAILED) {
2911 // anon_mmap() should only get called during VM initialization,
2912 // don't need lock (actually we can skip locking even it can be called
2913 // from multiple threads, because _highest_vm_reserved_address is just a
2914 // hint about the upper limit of non-stack memory regions.)
2915 if ((address)addr + bytes > _highest_vm_reserved_address) {
2916 _highest_vm_reserved_address = (address)addr + bytes;
2917 }
2918 }
2920 return addr == MAP_FAILED ? NULL : addr;
2921 }
2923 // Don't update _highest_vm_reserved_address, because there might be memory
2924 // regions above addr + size. If so, releasing a memory region only creates
2925 // a hole in the address space, it doesn't help prevent heap-stack collision.
2926 //
2927 static int anon_munmap(char * addr, size_t size) {
2928 return ::munmap(addr, size) == 0;
2929 }
2931 char* os::pd_reserve_memory(size_t bytes, char* requested_addr,
2932 size_t alignment_hint) {
2933 return anon_mmap(requested_addr, bytes, (requested_addr != NULL));
2934 }
2936 bool os::pd_release_memory(char* addr, size_t size) {
2937 return anon_munmap(addr, size);
2938 }
2940 static address highest_vm_reserved_address() {
2941 return _highest_vm_reserved_address;
2942 }
2944 static bool linux_mprotect(char* addr, size_t size, int prot) {
2945 // Linux wants the mprotect address argument to be page aligned.
2946 char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::page_size());
2948 // According to SUSv3, mprotect() should only be used with mappings
2949 // established by mmap(), and mmap() always maps whole pages. Unaligned
2950 // 'addr' likely indicates problem in the VM (e.g. trying to change
2951 // protection of malloc'ed or statically allocated memory). Check the
2952 // caller if you hit this assert.
2953 assert(addr == bottom, "sanity check");
2955 size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Linux::page_size());
2956 return ::mprotect(bottom, size, prot) == 0;
2957 }
2959 // Set protections specified
2960 bool os::protect_memory(char* addr, size_t bytes, ProtType prot,
2961 bool is_committed) {
2962 unsigned int p = 0;
2963 switch (prot) {
2964 case MEM_PROT_NONE: p = PROT_NONE; break;
2965 case MEM_PROT_READ: p = PROT_READ; break;
2966 case MEM_PROT_RW: p = PROT_READ|PROT_WRITE; break;
2967 case MEM_PROT_RWX: p = PROT_READ|PROT_WRITE|PROT_EXEC; break;
2968 default:
2969 ShouldNotReachHere();
2970 }
2971 // is_committed is unused.
2972 return linux_mprotect(addr, bytes, p);
2973 }
2975 bool os::guard_memory(char* addr, size_t size) {
2976 return linux_mprotect(addr, size, PROT_NONE);
2977 }
2979 bool os::unguard_memory(char* addr, size_t size) {
2980 return linux_mprotect(addr, size, PROT_READ|PROT_WRITE);
2981 }
2983 bool os::Linux::hugetlbfs_sanity_check(bool warn, size_t page_size) {
2984 bool result = false;
2985 void *p = mmap (NULL, page_size, PROT_READ|PROT_WRITE,
2986 MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB,
2987 -1, 0);
2989 if (p != (void *) -1) {
2990 // We don't know if this really is a huge page or not.
2991 FILE *fp = fopen("/proc/self/maps", "r");
2992 if (fp) {
2993 while (!feof(fp)) {
2994 char chars[257];
2995 long x = 0;
2996 if (fgets(chars, sizeof(chars), fp)) {
2997 if (sscanf(chars, "%lx-%*x", &x) == 1
2998 && x == (long)p) {
2999 if (strstr (chars, "hugepage")) {
3000 result = true;
3001 break;
3002 }
3003 }
3004 }
3005 }
3006 fclose(fp);
3007 }
3008 munmap (p, page_size);
3009 if (result)
3010 return true;
3011 }
3013 if (warn) {
3014 warning("HugeTLBFS is not supported by the operating system.");
3015 }
3017 return result;
3018 }
3020 /*
3021 * Set the coredump_filter bits to include largepages in core dump (bit 6)
3022 *
3023 * From the coredump_filter documentation:
3024 *
3025 * - (bit 0) anonymous private memory
3026 * - (bit 1) anonymous shared memory
3027 * - (bit 2) file-backed private memory
3028 * - (bit 3) file-backed shared memory
3029 * - (bit 4) ELF header pages in file-backed private memory areas (it is
3030 * effective only if the bit 2 is cleared)
3031 * - (bit 5) hugetlb private memory
3032 * - (bit 6) hugetlb shared memory
3033 */
3034 static void set_coredump_filter(void) {
3035 FILE *f;
3036 long cdm;
3038 if ((f = fopen("/proc/self/coredump_filter", "r+")) == NULL) {
3039 return;
3040 }
3042 if (fscanf(f, "%lx", &cdm) != 1) {
3043 fclose(f);
3044 return;
3045 }
3047 rewind(f);
3049 if ((cdm & LARGEPAGES_BIT) == 0) {
3050 cdm |= LARGEPAGES_BIT;
3051 fprintf(f, "%#lx", cdm);
3052 }
3054 fclose(f);
3055 }
3057 // Large page support
3059 static size_t _large_page_size = 0;
3061 void os::large_page_init() {
3062 if (!UseLargePages) {
3063 UseHugeTLBFS = false;
3064 UseSHM = false;
3065 return;
3066 }
3068 if (FLAG_IS_DEFAULT(UseHugeTLBFS) && FLAG_IS_DEFAULT(UseSHM)) {
3069 // If UseLargePages is specified on the command line try both methods,
3070 // if it's default, then try only HugeTLBFS.
3071 if (FLAG_IS_DEFAULT(UseLargePages)) {
3072 UseHugeTLBFS = true;
3073 } else {
3074 UseHugeTLBFS = UseSHM = true;
3075 }
3076 }
3078 if (LargePageSizeInBytes) {
3079 _large_page_size = LargePageSizeInBytes;
3080 } else {
3081 // large_page_size on Linux is used to round up heap size. x86 uses either
3082 // 2M or 4M page, depending on whether PAE (Physical Address Extensions)
3083 // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use
3084 // page as large as 256M.
3085 //
3086 // Here we try to figure out page size by parsing /proc/meminfo and looking
3087 // for a line with the following format:
3088 // Hugepagesize: 2048 kB
3089 //
3090 // If we can't determine the value (e.g. /proc is not mounted, or the text
3091 // format has been changed), we'll use the largest page size supported by
3092 // the processor.
3094 #ifndef ZERO
3095 _large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M)
3096 ARM_ONLY(2 * M) PPC_ONLY(4 * M);
3097 #endif // ZERO
3099 FILE *fp = fopen("/proc/meminfo", "r");
3100 if (fp) {
3101 while (!feof(fp)) {
3102 int x = 0;
3103 char buf[16];
3104 if (fscanf(fp, "Hugepagesize: %d", &x) == 1) {
3105 if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) {
3106 _large_page_size = x * K;
3107 break;
3108 }
3109 } else {
3110 // skip to next line
3111 for (;;) {
3112 int ch = fgetc(fp);
3113 if (ch == EOF || ch == (int)'\n') break;
3114 }
3115 }
3116 }
3117 fclose(fp);
3118 }
3119 }
3121 // print a warning if any large page related flag is specified on command line
3122 bool warn_on_failure = !FLAG_IS_DEFAULT(UseHugeTLBFS);
3124 const size_t default_page_size = (size_t)Linux::page_size();
3125 if (_large_page_size > default_page_size) {
3126 _page_sizes[0] = _large_page_size;
3127 _page_sizes[1] = default_page_size;
3128 _page_sizes[2] = 0;
3129 }
3130 UseHugeTLBFS = UseHugeTLBFS &&
3131 Linux::hugetlbfs_sanity_check(warn_on_failure, _large_page_size);
3133 if (UseHugeTLBFS)
3134 UseSHM = false;
3136 UseLargePages = UseHugeTLBFS || UseSHM;
3138 set_coredump_filter();
3139 }
3141 #ifndef SHM_HUGETLB
3142 #define SHM_HUGETLB 04000
3143 #endif
3145 char* os::reserve_memory_special(size_t bytes, char* req_addr, bool exec) {
3146 // "exec" is passed in but not used. Creating the shared image for
3147 // the code cache doesn't have an SHM_X executable permission to check.
3148 assert(UseLargePages && UseSHM, "only for SHM large pages");
3150 key_t key = IPC_PRIVATE;
3151 char *addr;
3153 bool warn_on_failure = UseLargePages &&
3154 (!FLAG_IS_DEFAULT(UseLargePages) ||
3155 !FLAG_IS_DEFAULT(LargePageSizeInBytes)
3156 );
3157 char msg[128];
3159 // Create a large shared memory region to attach to based on size.
3160 // Currently, size is the total size of the heap
3161 int shmid = shmget(key, bytes, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W);
3162 if (shmid == -1) {
3163 // Possible reasons for shmget failure:
3164 // 1. shmmax is too small for Java heap.
3165 // > check shmmax value: cat /proc/sys/kernel/shmmax
3166 // > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax
3167 // 2. not enough large page memory.
3168 // > check available large pages: cat /proc/meminfo
3169 // > increase amount of large pages:
3170 // echo new_value > /proc/sys/vm/nr_hugepages
3171 // Note 1: different Linux may use different name for this property,
3172 // e.g. on Redhat AS-3 it is "hugetlb_pool".
3173 // Note 2: it's possible there's enough physical memory available but
3174 // they are so fragmented after a long run that they can't
3175 // coalesce into large pages. Try to reserve large pages when
3176 // the system is still "fresh".
3177 if (warn_on_failure) {
3178 jio_snprintf(msg, sizeof(msg), "Failed to reserve shared memory (errno = %d).", errno);
3179 warning(msg);
3180 }
3181 return NULL;
3182 }
3184 // attach to the region
3185 addr = (char*)shmat(shmid, req_addr, 0);
3186 int err = errno;
3188 // Remove shmid. If shmat() is successful, the actual shared memory segment
3189 // will be deleted when it's detached by shmdt() or when the process
3190 // terminates. If shmat() is not successful this will remove the shared
3191 // segment immediately.
3192 shmctl(shmid, IPC_RMID, NULL);
3194 if ((intptr_t)addr == -1) {
3195 if (warn_on_failure) {
3196 jio_snprintf(msg, sizeof(msg), "Failed to attach shared memory (errno = %d).", err);
3197 warning(msg);
3198 }
3199 return NULL;
3200 }
3202 if ((addr != NULL) && UseNUMAInterleaving) {
3203 numa_make_global(addr, bytes);
3204 }
3206 // The memory is committed
3207 address pc = CALLER_PC;
3208 MemTracker::record_virtual_memory_reserve((address)addr, bytes, pc);
3209 MemTracker::record_virtual_memory_commit((address)addr, bytes, pc);
3211 return addr;
3212 }
3214 bool os::release_memory_special(char* base, size_t bytes) {
3215 // detaching the SHM segment will also delete it, see reserve_memory_special()
3216 int rslt = shmdt(base);
3217 if (rslt == 0) {
3218 MemTracker::record_virtual_memory_uncommit((address)base, bytes);
3219 MemTracker::record_virtual_memory_release((address)base, bytes);
3220 return true;
3221 } else {
3222 return false;
3223 }
3224 }
3226 size_t os::large_page_size() {
3227 return _large_page_size;
3228 }
3230 // HugeTLBFS allows application to commit large page memory on demand;
3231 // with SysV SHM the entire memory region must be allocated as shared
3232 // memory.
3233 bool os::can_commit_large_page_memory() {
3234 return UseHugeTLBFS;
3235 }
3237 bool os::can_execute_large_page_memory() {
3238 return UseHugeTLBFS;
3239 }
3241 // Reserve memory at an arbitrary address, only if that area is
3242 // available (and not reserved for something else).
3244 char* os::pd_attempt_reserve_memory_at(size_t bytes, char* requested_addr) {
3245 const int max_tries = 10;
3246 char* base[max_tries];
3247 size_t size[max_tries];
3248 const size_t gap = 0x000000;
3250 // Assert only that the size is a multiple of the page size, since
3251 // that's all that mmap requires, and since that's all we really know
3252 // about at this low abstraction level. If we need higher alignment,
3253 // we can either pass an alignment to this method or verify alignment
3254 // in one of the methods further up the call chain. See bug 5044738.
3255 assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block");
3257 // Repeatedly allocate blocks until the block is allocated at the
3258 // right spot. Give up after max_tries. Note that reserve_memory() will
3259 // automatically update _highest_vm_reserved_address if the call is
3260 // successful. The variable tracks the highest memory address every reserved
3261 // by JVM. It is used to detect heap-stack collision if running with
3262 // fixed-stack LinuxThreads. Because here we may attempt to reserve more
3263 // space than needed, it could confuse the collision detecting code. To
3264 // solve the problem, save current _highest_vm_reserved_address and
3265 // calculate the correct value before return.
3266 address old_highest = _highest_vm_reserved_address;
3268 // Linux mmap allows caller to pass an address as hint; give it a try first,
3269 // if kernel honors the hint then we can return immediately.
3270 char * addr = anon_mmap(requested_addr, bytes, false);
3271 if (addr == requested_addr) {
3272 return requested_addr;
3273 }
3275 if (addr != NULL) {
3276 // mmap() is successful but it fails to reserve at the requested address
3277 anon_munmap(addr, bytes);
3278 }
3280 int i;
3281 for (i = 0; i < max_tries; ++i) {
3282 base[i] = reserve_memory(bytes);
3284 if (base[i] != NULL) {
3285 // Is this the block we wanted?
3286 if (base[i] == requested_addr) {
3287 size[i] = bytes;
3288 break;
3289 }
3291 // Does this overlap the block we wanted? Give back the overlapped
3292 // parts and try again.
3294 size_t top_overlap = requested_addr + (bytes + gap) - base[i];
3295 if (top_overlap >= 0 && top_overlap < bytes) {
3296 unmap_memory(base[i], top_overlap);
3297 base[i] += top_overlap;
3298 size[i] = bytes - top_overlap;
3299 } else {
3300 size_t bottom_overlap = base[i] + bytes - requested_addr;
3301 if (bottom_overlap >= 0 && bottom_overlap < bytes) {
3302 unmap_memory(requested_addr, bottom_overlap);
3303 size[i] = bytes - bottom_overlap;
3304 } else {
3305 size[i] = bytes;
3306 }
3307 }
3308 }
3309 }
3311 // Give back the unused reserved pieces.
3313 for (int j = 0; j < i; ++j) {
3314 if (base[j] != NULL) {
3315 unmap_memory(base[j], size[j]);
3316 }
3317 }
3319 if (i < max_tries) {
3320 _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes);
3321 return requested_addr;
3322 } else {
3323 _highest_vm_reserved_address = old_highest;
3324 return NULL;
3325 }
3326 }
3328 size_t os::read(int fd, void *buf, unsigned int nBytes) {
3329 return ::read(fd, buf, nBytes);
3330 }
3332 // TODO-FIXME: reconcile Solaris' os::sleep with the linux variation.
3333 // Solaris uses poll(), linux uses park().
3334 // Poll() is likely a better choice, assuming that Thread.interrupt()
3335 // generates a SIGUSRx signal. Note that SIGUSR1 can interfere with
3336 // SIGSEGV, see 4355769.
3338 int os::sleep(Thread* thread, jlong millis, bool interruptible) {
3339 assert(thread == Thread::current(), "thread consistency check");
3341 ParkEvent * const slp = thread->_SleepEvent ;
3342 slp->reset() ;
3343 OrderAccess::fence() ;
3345 if (interruptible) {
3346 jlong prevtime = javaTimeNanos();
3348 for (;;) {
3349 if (os::is_interrupted(thread, true)) {
3350 return OS_INTRPT;
3351 }
3353 jlong newtime = javaTimeNanos();
3355 if (newtime - prevtime < 0) {
3356 // time moving backwards, should only happen if no monotonic clock
3357 // not a guarantee() because JVM should not abort on kernel/glibc bugs
3358 assert(!Linux::supports_monotonic_clock(), "time moving backwards");
3359 } else {
3360 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC;
3361 }
3363 if(millis <= 0) {
3364 return OS_OK;
3365 }
3367 prevtime = newtime;
3369 {
3370 assert(thread->is_Java_thread(), "sanity check");
3371 JavaThread *jt = (JavaThread *) thread;
3372 ThreadBlockInVM tbivm(jt);
3373 OSThreadWaitState osts(jt->osthread(), false /* not Object.wait() */);
3375 jt->set_suspend_equivalent();
3376 // cleared by handle_special_suspend_equivalent_condition() or
3377 // java_suspend_self() via check_and_wait_while_suspended()
3379 slp->park(millis);
3381 // were we externally suspended while we were waiting?
3382 jt->check_and_wait_while_suspended();
3383 }
3384 }
3385 } else {
3386 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */);
3387 jlong prevtime = javaTimeNanos();
3389 for (;;) {
3390 // It'd be nice to avoid the back-to-back javaTimeNanos() calls on
3391 // the 1st iteration ...
3392 jlong newtime = javaTimeNanos();
3394 if (newtime - prevtime < 0) {
3395 // time moving backwards, should only happen if no monotonic clock
3396 // not a guarantee() because JVM should not abort on kernel/glibc bugs
3397 assert(!Linux::supports_monotonic_clock(), "time moving backwards");
3398 } else {
3399 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC;
3400 }
3402 if(millis <= 0) break ;
3404 prevtime = newtime;
3405 slp->park(millis);
3406 }
3407 return OS_OK ;
3408 }
3409 }
3411 int os::naked_sleep() {
3412 // %% make the sleep time an integer flag. for now use 1 millisec.
3413 return os::sleep(Thread::current(), 1, false);
3414 }
3416 // Sleep forever; naked call to OS-specific sleep; use with CAUTION
3417 void os::infinite_sleep() {
3418 while (true) { // sleep forever ...
3419 ::sleep(100); // ... 100 seconds at a time
3420 }
3421 }
3423 // Used to convert frequent JVM_Yield() to nops
3424 bool os::dont_yield() {
3425 return DontYieldALot;
3426 }
3428 void os::yield() {
3429 sched_yield();
3430 }
3432 os::YieldResult os::NakedYield() { sched_yield(); return os::YIELD_UNKNOWN ;}
3434 void os::yield_all(int attempts) {
3435 // Yields to all threads, including threads with lower priorities
3436 // Threads on Linux are all with same priority. The Solaris style
3437 // os::yield_all() with nanosleep(1ms) is not necessary.
3438 sched_yield();
3439 }
3441 // Called from the tight loops to possibly influence time-sharing heuristics
3442 void os::loop_breaker(int attempts) {
3443 os::yield_all(attempts);
3444 }
3446 ////////////////////////////////////////////////////////////////////////////////
3447 // thread priority support
3449 // Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER
3450 // only supports dynamic priority, static priority must be zero. For real-time
3451 // applications, Linux supports SCHED_RR which allows static priority (1-99).
3452 // However, for large multi-threaded applications, SCHED_RR is not only slower
3453 // than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out
3454 // of 5 runs - Sep 2005).
3455 //
3456 // The following code actually changes the niceness of kernel-thread/LWP. It
3457 // has an assumption that setpriority() only modifies one kernel-thread/LWP,
3458 // not the entire user process, and user level threads are 1:1 mapped to kernel
3459 // threads. It has always been the case, but could change in the future. For
3460 // this reason, the code should not be used as default (ThreadPriorityPolicy=0).
3461 // It is only used when ThreadPriorityPolicy=1 and requires root privilege.
3463 int os::java_to_os_priority[CriticalPriority + 1] = {
3464 19, // 0 Entry should never be used
3466 4, // 1 MinPriority
3467 3, // 2
3468 2, // 3
3470 1, // 4
3471 0, // 5 NormPriority
3472 -1, // 6
3474 -2, // 7
3475 -3, // 8
3476 -4, // 9 NearMaxPriority
3478 -5, // 10 MaxPriority
3480 -5 // 11 CriticalPriority
3481 };
3483 static int prio_init() {
3484 if (ThreadPriorityPolicy == 1) {
3485 // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1
3486 // if effective uid is not root. Perhaps, a more elegant way of doing
3487 // this is to test CAP_SYS_NICE capability, but that will require libcap.so
3488 if (geteuid() != 0) {
3489 if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) {
3490 warning("-XX:ThreadPriorityPolicy requires root privilege on Linux");
3491 }
3492 ThreadPriorityPolicy = 0;
3493 }
3494 }
3495 if (UseCriticalJavaThreadPriority) {
3496 os::java_to_os_priority[MaxPriority] = os::java_to_os_priority[CriticalPriority];
3497 }
3498 return 0;
3499 }
3501 OSReturn os::set_native_priority(Thread* thread, int newpri) {
3502 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) return OS_OK;
3504 int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri);
3505 return (ret == 0) ? OS_OK : OS_ERR;
3506 }
3508 OSReturn os::get_native_priority(const Thread* const thread, int *priority_ptr) {
3509 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) {
3510 *priority_ptr = java_to_os_priority[NormPriority];
3511 return OS_OK;
3512 }
3514 errno = 0;
3515 *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id());
3516 return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR);
3517 }
3519 // Hint to the underlying OS that a task switch would not be good.
3520 // Void return because it's a hint and can fail.
3521 void os::hint_no_preempt() {}
3523 ////////////////////////////////////////////////////////////////////////////////
3524 // suspend/resume support
3526 // the low-level signal-based suspend/resume support is a remnant from the
3527 // old VM-suspension that used to be for java-suspension, safepoints etc,
3528 // within hotspot. Now there is a single use-case for this:
3529 // - calling get_thread_pc() on the VMThread by the flat-profiler task
3530 // that runs in the watcher thread.
3531 // The remaining code is greatly simplified from the more general suspension
3532 // code that used to be used.
3533 //
3534 // The protocol is quite simple:
3535 // - suspend:
3536 // - sends a signal to the target thread
3537 // - polls the suspend state of the osthread using a yield loop
3538 // - target thread signal handler (SR_handler) sets suspend state
3539 // and blocks in sigsuspend until continued
3540 // - resume:
3541 // - sets target osthread state to continue
3542 // - sends signal to end the sigsuspend loop in the SR_handler
3543 //
3544 // Note that the SR_lock plays no role in this suspend/resume protocol.
3545 //
3547 static void resume_clear_context(OSThread *osthread) {
3548 osthread->set_ucontext(NULL);
3549 osthread->set_siginfo(NULL);
3551 // notify the suspend action is completed, we have now resumed
3552 osthread->sr.clear_suspended();
3553 }
3555 static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo, ucontext_t* context) {
3556 osthread->set_ucontext(context);
3557 osthread->set_siginfo(siginfo);
3558 }
3560 //
3561 // Handler function invoked when a thread's execution is suspended or
3562 // resumed. We have to be careful that only async-safe functions are
3563 // called here (Note: most pthread functions are not async safe and
3564 // should be avoided.)
3565 //
3566 // Note: sigwait() is a more natural fit than sigsuspend() from an
3567 // interface point of view, but sigwait() prevents the signal hander
3568 // from being run. libpthread would get very confused by not having
3569 // its signal handlers run and prevents sigwait()'s use with the
3570 // mutex granting granting signal.
3571 //
3572 // Currently only ever called on the VMThread
3573 //
3574 static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) {
3575 // Save and restore errno to avoid confusing native code with EINTR
3576 // after sigsuspend.
3577 int old_errno = errno;
3579 Thread* thread = Thread::current();
3580 OSThread* osthread = thread->osthread();
3581 assert(thread->is_VM_thread(), "Must be VMThread");
3582 // read current suspend action
3583 int action = osthread->sr.suspend_action();
3584 if (action == os::Linux::SuspendResume::SR_SUSPEND) {
3585 suspend_save_context(osthread, siginfo, context);
3587 // Notify the suspend action is about to be completed. do_suspend()
3588 // waits until SR_SUSPENDED is set and then returns. We will wait
3589 // here for a resume signal and that completes the suspend-other
3590 // action. do_suspend/do_resume is always called as a pair from
3591 // the same thread - so there are no races
3593 // notify the caller
3594 osthread->sr.set_suspended();
3596 sigset_t suspend_set; // signals for sigsuspend()
3598 // get current set of blocked signals and unblock resume signal
3599 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set);
3600 sigdelset(&suspend_set, SR_signum);
3602 // wait here until we are resumed
3603 do {
3604 sigsuspend(&suspend_set);
3605 // ignore all returns until we get a resume signal
3606 } while (osthread->sr.suspend_action() != os::Linux::SuspendResume::SR_CONTINUE);
3608 resume_clear_context(osthread);
3610 } else {
3611 assert(action == os::Linux::SuspendResume::SR_CONTINUE, "unexpected sr action");
3612 // nothing special to do - just leave the handler
3613 }
3615 errno = old_errno;
3616 }
3619 static int SR_initialize() {
3620 struct sigaction act;
3621 char *s;
3622 /* Get signal number to use for suspend/resume */
3623 if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) {
3624 int sig = ::strtol(s, 0, 10);
3625 if (sig > 0 || sig < _NSIG) {
3626 SR_signum = sig;
3627 }
3628 }
3630 assert(SR_signum > SIGSEGV && SR_signum > SIGBUS,
3631 "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769");
3633 sigemptyset(&SR_sigset);
3634 sigaddset(&SR_sigset, SR_signum);
3636 /* Set up signal handler for suspend/resume */
3637 act.sa_flags = SA_RESTART|SA_SIGINFO;
3638 act.sa_handler = (void (*)(int)) SR_handler;
3640 // SR_signum is blocked by default.
3641 // 4528190 - We also need to block pthread restart signal (32 on all
3642 // supported Linux platforms). Note that LinuxThreads need to block
3643 // this signal for all threads to work properly. So we don't have
3644 // to use hard-coded signal number when setting up the mask.
3645 pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask);
3647 if (sigaction(SR_signum, &act, 0) == -1) {
3648 return -1;
3649 }
3651 // Save signal flag
3652 os::Linux::set_our_sigflags(SR_signum, act.sa_flags);
3653 return 0;
3654 }
3657 // returns true on success and false on error - really an error is fatal
3658 // but this seems the normal response to library errors
3659 static bool do_suspend(OSThread* osthread) {
3660 // mark as suspended and send signal
3661 osthread->sr.set_suspend_action(os::Linux::SuspendResume::SR_SUSPEND);
3662 int status = pthread_kill(osthread->pthread_id(), SR_signum);
3663 assert_status(status == 0, status, "pthread_kill");
3665 // check status and wait until notified of suspension
3666 if (status == 0) {
3667 for (int i = 0; !osthread->sr.is_suspended(); i++) {
3668 os::yield_all(i);
3669 }
3670 osthread->sr.set_suspend_action(os::Linux::SuspendResume::SR_NONE);
3671 return true;
3672 }
3673 else {
3674 osthread->sr.set_suspend_action(os::Linux::SuspendResume::SR_NONE);
3675 return false;
3676 }
3677 }
3679 static void do_resume(OSThread* osthread) {
3680 assert(osthread->sr.is_suspended(), "thread should be suspended");
3681 osthread->sr.set_suspend_action(os::Linux::SuspendResume::SR_CONTINUE);
3683 int status = pthread_kill(osthread->pthread_id(), SR_signum);
3684 assert_status(status == 0, status, "pthread_kill");
3685 // check status and wait unit notified of resumption
3686 if (status == 0) {
3687 for (int i = 0; osthread->sr.is_suspended(); i++) {
3688 os::yield_all(i);
3689 }
3690 }
3691 osthread->sr.set_suspend_action(os::Linux::SuspendResume::SR_NONE);
3692 }
3694 ////////////////////////////////////////////////////////////////////////////////
3695 // interrupt support
3697 void os::interrupt(Thread* thread) {
3698 assert(Thread::current() == thread || Threads_lock->owned_by_self(),
3699 "possibility of dangling Thread pointer");
3701 OSThread* osthread = thread->osthread();
3703 if (!osthread->interrupted()) {
3704 osthread->set_interrupted(true);
3705 // More than one thread can get here with the same value of osthread,
3706 // resulting in multiple notifications. We do, however, want the store
3707 // to interrupted() to be visible to other threads before we execute unpark().
3708 OrderAccess::fence();
3709 ParkEvent * const slp = thread->_SleepEvent ;
3710 if (slp != NULL) slp->unpark() ;
3711 }
3713 // For JSR166. Unpark even if interrupt status already was set
3714 if (thread->is_Java_thread())
3715 ((JavaThread*)thread)->parker()->unpark();
3717 ParkEvent * ev = thread->_ParkEvent ;
3718 if (ev != NULL) ev->unpark() ;
3720 }
3722 bool os::is_interrupted(Thread* thread, bool clear_interrupted) {
3723 assert(Thread::current() == thread || Threads_lock->owned_by_self(),
3724 "possibility of dangling Thread pointer");
3726 OSThread* osthread = thread->osthread();
3728 bool interrupted = osthread->interrupted();
3730 if (interrupted && clear_interrupted) {
3731 osthread->set_interrupted(false);
3732 // consider thread->_SleepEvent->reset() ... optional optimization
3733 }
3735 return interrupted;
3736 }
3738 ///////////////////////////////////////////////////////////////////////////////////
3739 // signal handling (except suspend/resume)
3741 // This routine may be used by user applications as a "hook" to catch signals.
3742 // The user-defined signal handler must pass unrecognized signals to this
3743 // routine, and if it returns true (non-zero), then the signal handler must
3744 // return immediately. If the flag "abort_if_unrecognized" is true, then this
3745 // routine will never retun false (zero), but instead will execute a VM panic
3746 // routine kill the process.
3747 //
3748 // If this routine returns false, it is OK to call it again. This allows
3749 // the user-defined signal handler to perform checks either before or after
3750 // the VM performs its own checks. Naturally, the user code would be making
3751 // a serious error if it tried to handle an exception (such as a null check
3752 // or breakpoint) that the VM was generating for its own correct operation.
3753 //
3754 // This routine may recognize any of the following kinds of signals:
3755 // SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1.
3756 // It should be consulted by handlers for any of those signals.
3757 //
3758 // The caller of this routine must pass in the three arguments supplied
3759 // to the function referred to in the "sa_sigaction" (not the "sa_handler")
3760 // field of the structure passed to sigaction(). This routine assumes that
3761 // the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART.
3762 //
3763 // Note that the VM will print warnings if it detects conflicting signal
3764 // handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers".
3765 //
3766 extern "C" JNIEXPORT int
3767 JVM_handle_linux_signal(int signo, siginfo_t* siginfo,
3768 void* ucontext, int abort_if_unrecognized);
3770 void signalHandler(int sig, siginfo_t* info, void* uc) {
3771 assert(info != NULL && uc != NULL, "it must be old kernel");
3772 int orig_errno = errno; // Preserve errno value over signal handler.
3773 JVM_handle_linux_signal(sig, info, uc, true);
3774 errno = orig_errno;
3775 }
3778 // This boolean allows users to forward their own non-matching signals
3779 // to JVM_handle_linux_signal, harmlessly.
3780 bool os::Linux::signal_handlers_are_installed = false;
3782 // For signal-chaining
3783 struct sigaction os::Linux::sigact[MAXSIGNUM];
3784 unsigned int os::Linux::sigs = 0;
3785 bool os::Linux::libjsig_is_loaded = false;
3786 typedef struct sigaction *(*get_signal_t)(int);
3787 get_signal_t os::Linux::get_signal_action = NULL;
3789 struct sigaction* os::Linux::get_chained_signal_action(int sig) {
3790 struct sigaction *actp = NULL;
3792 if (libjsig_is_loaded) {
3793 // Retrieve the old signal handler from libjsig
3794 actp = (*get_signal_action)(sig);
3795 }
3796 if (actp == NULL) {
3797 // Retrieve the preinstalled signal handler from jvm
3798 actp = get_preinstalled_handler(sig);
3799 }
3801 return actp;
3802 }
3804 static bool call_chained_handler(struct sigaction *actp, int sig,
3805 siginfo_t *siginfo, void *context) {
3806 // Call the old signal handler
3807 if (actp->sa_handler == SIG_DFL) {
3808 // It's more reasonable to let jvm treat it as an unexpected exception
3809 // instead of taking the default action.
3810 return false;
3811 } else if (actp->sa_handler != SIG_IGN) {
3812 if ((actp->sa_flags & SA_NODEFER) == 0) {
3813 // automaticlly block the signal
3814 sigaddset(&(actp->sa_mask), sig);
3815 }
3817 sa_handler_t hand;
3818 sa_sigaction_t sa;
3819 bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0;
3820 // retrieve the chained handler
3821 if (siginfo_flag_set) {
3822 sa = actp->sa_sigaction;
3823 } else {
3824 hand = actp->sa_handler;
3825 }
3827 if ((actp->sa_flags & SA_RESETHAND) != 0) {
3828 actp->sa_handler = SIG_DFL;
3829 }
3831 // try to honor the signal mask
3832 sigset_t oset;
3833 pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset);
3835 // call into the chained handler
3836 if (siginfo_flag_set) {
3837 (*sa)(sig, siginfo, context);
3838 } else {
3839 (*hand)(sig);
3840 }
3842 // restore the signal mask
3843 pthread_sigmask(SIG_SETMASK, &oset, 0);
3844 }
3845 // Tell jvm's signal handler the signal is taken care of.
3846 return true;
3847 }
3849 bool os::Linux::chained_handler(int sig, siginfo_t* siginfo, void* context) {
3850 bool chained = false;
3851 // signal-chaining
3852 if (UseSignalChaining) {
3853 struct sigaction *actp = get_chained_signal_action(sig);
3854 if (actp != NULL) {
3855 chained = call_chained_handler(actp, sig, siginfo, context);
3856 }
3857 }
3858 return chained;
3859 }
3861 struct sigaction* os::Linux::get_preinstalled_handler(int sig) {
3862 if ((( (unsigned int)1 << sig ) & sigs) != 0) {
3863 return &sigact[sig];
3864 }
3865 return NULL;
3866 }
3868 void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) {
3869 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
3870 sigact[sig] = oldAct;
3871 sigs |= (unsigned int)1 << sig;
3872 }
3874 // for diagnostic
3875 int os::Linux::sigflags[MAXSIGNUM];
3877 int os::Linux::get_our_sigflags(int sig) {
3878 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
3879 return sigflags[sig];
3880 }
3882 void os::Linux::set_our_sigflags(int sig, int flags) {
3883 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
3884 sigflags[sig] = flags;
3885 }
3887 void os::Linux::set_signal_handler(int sig, bool set_installed) {
3888 // Check for overwrite.
3889 struct sigaction oldAct;
3890 sigaction(sig, (struct sigaction*)NULL, &oldAct);
3892 void* oldhand = oldAct.sa_sigaction
3893 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction)
3894 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler);
3895 if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) &&
3896 oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) &&
3897 oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) {
3898 if (AllowUserSignalHandlers || !set_installed) {
3899 // Do not overwrite; user takes responsibility to forward to us.
3900 return;
3901 } else if (UseSignalChaining) {
3902 // save the old handler in jvm
3903 save_preinstalled_handler(sig, oldAct);
3904 // libjsig also interposes the sigaction() call below and saves the
3905 // old sigaction on it own.
3906 } else {
3907 fatal(err_msg("Encountered unexpected pre-existing sigaction handler "
3908 "%#lx for signal %d.", (long)oldhand, sig));
3909 }
3910 }
3912 struct sigaction sigAct;
3913 sigfillset(&(sigAct.sa_mask));
3914 sigAct.sa_handler = SIG_DFL;
3915 if (!set_installed) {
3916 sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
3917 } else {
3918 sigAct.sa_sigaction = signalHandler;
3919 sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
3920 }
3921 // Save flags, which are set by ours
3922 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
3923 sigflags[sig] = sigAct.sa_flags;
3925 int ret = sigaction(sig, &sigAct, &oldAct);
3926 assert(ret == 0, "check");
3928 void* oldhand2 = oldAct.sa_sigaction
3929 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction)
3930 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler);
3931 assert(oldhand2 == oldhand, "no concurrent signal handler installation");
3932 }
3934 // install signal handlers for signals that HotSpot needs to
3935 // handle in order to support Java-level exception handling.
3937 void os::Linux::install_signal_handlers() {
3938 if (!signal_handlers_are_installed) {
3939 signal_handlers_are_installed = true;
3941 // signal-chaining
3942 typedef void (*signal_setting_t)();
3943 signal_setting_t begin_signal_setting = NULL;
3944 signal_setting_t end_signal_setting = NULL;
3945 begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
3946 dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting"));
3947 if (begin_signal_setting != NULL) {
3948 end_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
3949 dlsym(RTLD_DEFAULT, "JVM_end_signal_setting"));
3950 get_signal_action = CAST_TO_FN_PTR(get_signal_t,
3951 dlsym(RTLD_DEFAULT, "JVM_get_signal_action"));
3952 libjsig_is_loaded = true;
3953 assert(UseSignalChaining, "should enable signal-chaining");
3954 }
3955 if (libjsig_is_loaded) {
3956 // Tell libjsig jvm is setting signal handlers
3957 (*begin_signal_setting)();
3958 }
3960 set_signal_handler(SIGSEGV, true);
3961 set_signal_handler(SIGPIPE, true);
3962 set_signal_handler(SIGBUS, true);
3963 set_signal_handler(SIGILL, true);
3964 set_signal_handler(SIGFPE, true);
3965 set_signal_handler(SIGXFSZ, true);
3967 if (libjsig_is_loaded) {
3968 // Tell libjsig jvm finishes setting signal handlers
3969 (*end_signal_setting)();
3970 }
3972 // We don't activate signal checker if libjsig is in place, we trust ourselves
3973 // and if UserSignalHandler is installed all bets are off.
3974 // Log that signal checking is off only if -verbose:jni is specified.
3975 if (CheckJNICalls) {
3976 if (libjsig_is_loaded) {
3977 if (PrintJNIResolving) {
3978 tty->print_cr("Info: libjsig is activated, all active signal checking is disabled");
3979 }
3980 check_signals = false;
3981 }
3982 if (AllowUserSignalHandlers) {
3983 if (PrintJNIResolving) {
3984 tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled");
3985 }
3986 check_signals = false;
3987 }
3988 }
3989 }
3990 }
3992 // This is the fastest way to get thread cpu time on Linux.
3993 // Returns cpu time (user+sys) for any thread, not only for current.
3994 // POSIX compliant clocks are implemented in the kernels 2.6.16+.
3995 // It might work on 2.6.10+ with a special kernel/glibc patch.
3996 // For reference, please, see IEEE Std 1003.1-2004:
3997 // http://www.unix.org/single_unix_specification
3999 jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) {
4000 struct timespec tp;
4001 int rc = os::Linux::clock_gettime(clockid, &tp);
4002 assert(rc == 0, "clock_gettime is expected to return 0 code");
4004 return (tp.tv_sec * NANOSECS_PER_SEC) + tp.tv_nsec;
4005 }
4007 /////
4008 // glibc on Linux platform uses non-documented flag
4009 // to indicate, that some special sort of signal
4010 // trampoline is used.
4011 // We will never set this flag, and we should
4012 // ignore this flag in our diagnostic
4013 #ifdef SIGNIFICANT_SIGNAL_MASK
4014 #undef SIGNIFICANT_SIGNAL_MASK
4015 #endif
4016 #define SIGNIFICANT_SIGNAL_MASK (~0x04000000)
4018 static const char* get_signal_handler_name(address handler,
4019 char* buf, int buflen) {
4020 int offset;
4021 bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset);
4022 if (found) {
4023 // skip directory names
4024 const char *p1, *p2;
4025 p1 = buf;
4026 size_t len = strlen(os::file_separator());
4027 while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len;
4028 jio_snprintf(buf, buflen, "%s+0x%x", p1, offset);
4029 } else {
4030 jio_snprintf(buf, buflen, PTR_FORMAT, handler);
4031 }
4032 return buf;
4033 }
4035 static void print_signal_handler(outputStream* st, int sig,
4036 char* buf, size_t buflen) {
4037 struct sigaction sa;
4039 sigaction(sig, NULL, &sa);
4041 // See comment for SIGNIFICANT_SIGNAL_MASK define
4042 sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
4044 st->print("%s: ", os::exception_name(sig, buf, buflen));
4046 address handler = (sa.sa_flags & SA_SIGINFO)
4047 ? CAST_FROM_FN_PTR(address, sa.sa_sigaction)
4048 : CAST_FROM_FN_PTR(address, sa.sa_handler);
4050 if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) {
4051 st->print("SIG_DFL");
4052 } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) {
4053 st->print("SIG_IGN");
4054 } else {
4055 st->print("[%s]", get_signal_handler_name(handler, buf, buflen));
4056 }
4058 st->print(", sa_mask[0]=" PTR32_FORMAT, *(uint32_t*)&sa.sa_mask);
4060 address rh = VMError::get_resetted_sighandler(sig);
4061 // May be, handler was resetted by VMError?
4062 if(rh != NULL) {
4063 handler = rh;
4064 sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK;
4065 }
4067 st->print(", sa_flags=" PTR32_FORMAT, sa.sa_flags);
4069 // Check: is it our handler?
4070 if(handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) ||
4071 handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) {
4072 // It is our signal handler
4073 // check for flags, reset system-used one!
4074 if((int)sa.sa_flags != os::Linux::get_our_sigflags(sig)) {
4075 st->print(
4076 ", flags was changed from " PTR32_FORMAT ", consider using jsig library",
4077 os::Linux::get_our_sigflags(sig));
4078 }
4079 }
4080 st->cr();
4081 }
4084 #define DO_SIGNAL_CHECK(sig) \
4085 if (!sigismember(&check_signal_done, sig)) \
4086 os::Linux::check_signal_handler(sig)
4088 // This method is a periodic task to check for misbehaving JNI applications
4089 // under CheckJNI, we can add any periodic checks here
4091 void os::run_periodic_checks() {
4093 if (check_signals == false) return;
4095 // SEGV and BUS if overridden could potentially prevent
4096 // generation of hs*.log in the event of a crash, debugging
4097 // such a case can be very challenging, so we absolutely
4098 // check the following for a good measure:
4099 DO_SIGNAL_CHECK(SIGSEGV);
4100 DO_SIGNAL_CHECK(SIGILL);
4101 DO_SIGNAL_CHECK(SIGFPE);
4102 DO_SIGNAL_CHECK(SIGBUS);
4103 DO_SIGNAL_CHECK(SIGPIPE);
4104 DO_SIGNAL_CHECK(SIGXFSZ);
4107 // ReduceSignalUsage allows the user to override these handlers
4108 // see comments at the very top and jvm_solaris.h
4109 if (!ReduceSignalUsage) {
4110 DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL);
4111 DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL);
4112 DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL);
4113 DO_SIGNAL_CHECK(BREAK_SIGNAL);
4114 }
4116 DO_SIGNAL_CHECK(SR_signum);
4117 DO_SIGNAL_CHECK(INTERRUPT_SIGNAL);
4118 }
4120 typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *);
4122 static os_sigaction_t os_sigaction = NULL;
4124 void os::Linux::check_signal_handler(int sig) {
4125 char buf[O_BUFLEN];
4126 address jvmHandler = NULL;
4129 struct sigaction act;
4130 if (os_sigaction == NULL) {
4131 // only trust the default sigaction, in case it has been interposed
4132 os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction");
4133 if (os_sigaction == NULL) return;
4134 }
4136 os_sigaction(sig, (struct sigaction*)NULL, &act);
4139 act.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
4141 address thisHandler = (act.sa_flags & SA_SIGINFO)
4142 ? CAST_FROM_FN_PTR(address, act.sa_sigaction)
4143 : CAST_FROM_FN_PTR(address, act.sa_handler) ;
4146 switch(sig) {
4147 case SIGSEGV:
4148 case SIGBUS:
4149 case SIGFPE:
4150 case SIGPIPE:
4151 case SIGILL:
4152 case SIGXFSZ:
4153 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler);
4154 break;
4156 case SHUTDOWN1_SIGNAL:
4157 case SHUTDOWN2_SIGNAL:
4158 case SHUTDOWN3_SIGNAL:
4159 case BREAK_SIGNAL:
4160 jvmHandler = (address)user_handler();
4161 break;
4163 case INTERRUPT_SIGNAL:
4164 jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL);
4165 break;
4167 default:
4168 if (sig == SR_signum) {
4169 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler);
4170 } else {
4171 return;
4172 }
4173 break;
4174 }
4176 if (thisHandler != jvmHandler) {
4177 tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN));
4178 tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN));
4179 tty->print_cr(" found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN));
4180 // No need to check this sig any longer
4181 sigaddset(&check_signal_done, sig);
4182 } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) {
4183 tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN));
4184 tty->print("expected:" PTR32_FORMAT, os::Linux::get_our_sigflags(sig));
4185 tty->print_cr(" found:" PTR32_FORMAT, act.sa_flags);
4186 // No need to check this sig any longer
4187 sigaddset(&check_signal_done, sig);
4188 }
4190 // Dump all the signal
4191 if (sigismember(&check_signal_done, sig)) {
4192 print_signal_handlers(tty, buf, O_BUFLEN);
4193 }
4194 }
4196 extern void report_error(char* file_name, int line_no, char* title, char* format, ...);
4198 extern bool signal_name(int signo, char* buf, size_t len);
4200 const char* os::exception_name(int exception_code, char* buf, size_t size) {
4201 if (0 < exception_code && exception_code <= SIGRTMAX) {
4202 // signal
4203 if (!signal_name(exception_code, buf, size)) {
4204 jio_snprintf(buf, size, "SIG%d", exception_code);
4205 }
4206 return buf;
4207 } else {
4208 return NULL;
4209 }
4210 }
4212 // this is called _before_ the most of global arguments have been parsed
4213 void os::init(void) {
4214 char dummy; /* used to get a guess on initial stack address */
4215 // first_hrtime = gethrtime();
4217 // With LinuxThreads the JavaMain thread pid (primordial thread)
4218 // is different than the pid of the java launcher thread.
4219 // So, on Linux, the launcher thread pid is passed to the VM
4220 // via the sun.java.launcher.pid property.
4221 // Use this property instead of getpid() if it was correctly passed.
4222 // See bug 6351349.
4223 pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid();
4225 _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid();
4227 clock_tics_per_sec = sysconf(_SC_CLK_TCK);
4229 init_random(1234567);
4231 ThreadCritical::initialize();
4233 Linux::set_page_size(sysconf(_SC_PAGESIZE));
4234 if (Linux::page_size() == -1) {
4235 fatal(err_msg("os_linux.cpp: os::init: sysconf failed (%s)",
4236 strerror(errno)));
4237 }
4238 init_page_sizes((size_t) Linux::page_size());
4240 Linux::initialize_system_info();
4242 // main_thread points to the aboriginal thread
4243 Linux::_main_thread = pthread_self();
4245 Linux::clock_init();
4246 initial_time_count = os::elapsed_counter();
4247 pthread_mutex_init(&dl_mutex, NULL);
4248 }
4250 // To install functions for atexit system call
4251 extern "C" {
4252 static void perfMemory_exit_helper() {
4253 perfMemory_exit();
4254 }
4255 }
4257 // this is called _after_ the global arguments have been parsed
4258 jint os::init_2(void)
4259 {
4260 Linux::fast_thread_clock_init();
4262 // Allocate a single page and mark it as readable for safepoint polling
4263 address polling_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
4264 guarantee( polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page" );
4266 os::set_polling_page( polling_page );
4268 #ifndef PRODUCT
4269 if(Verbose && PrintMiscellaneous)
4270 tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n", (intptr_t)polling_page);
4271 #endif
4273 if (!UseMembar) {
4274 address mem_serialize_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
4275 guarantee( mem_serialize_page != NULL, "mmap Failed for memory serialize page");
4276 os::set_memory_serialize_page( mem_serialize_page );
4278 #ifndef PRODUCT
4279 if(Verbose && PrintMiscellaneous)
4280 tty->print("[Memory Serialize Page address: " INTPTR_FORMAT "]\n", (intptr_t)mem_serialize_page);
4281 #endif
4282 }
4284 os::large_page_init();
4286 // initialize suspend/resume support - must do this before signal_sets_init()
4287 if (SR_initialize() != 0) {
4288 perror("SR_initialize failed");
4289 return JNI_ERR;
4290 }
4292 Linux::signal_sets_init();
4293 Linux::install_signal_handlers();
4295 // Check minimum allowable stack size for thread creation and to initialize
4296 // the java system classes, including StackOverflowError - depends on page
4297 // size. Add a page for compiler2 recursion in main thread.
4298 // Add in 2*BytesPerWord times page size to account for VM stack during
4299 // class initialization depending on 32 or 64 bit VM.
4300 os::Linux::min_stack_allowed = MAX2(os::Linux::min_stack_allowed,
4301 (size_t)(StackYellowPages+StackRedPages+StackShadowPages+
4302 2*BytesPerWord COMPILER2_PRESENT(+1)) * Linux::page_size());
4304 size_t threadStackSizeInBytes = ThreadStackSize * K;
4305 if (threadStackSizeInBytes != 0 &&
4306 threadStackSizeInBytes < os::Linux::min_stack_allowed) {
4307 tty->print_cr("\nThe stack size specified is too small, "
4308 "Specify at least %dk",
4309 os::Linux::min_stack_allowed/ K);
4310 return JNI_ERR;
4311 }
4313 // Make the stack size a multiple of the page size so that
4314 // the yellow/red zones can be guarded.
4315 JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes,
4316 vm_page_size()));
4318 Linux::capture_initial_stack(JavaThread::stack_size_at_create());
4320 Linux::libpthread_init();
4321 if (PrintMiscellaneous && (Verbose || WizardMode)) {
4322 tty->print_cr("[HotSpot is running with %s, %s(%s)]\n",
4323 Linux::glibc_version(), Linux::libpthread_version(),
4324 Linux::is_floating_stack() ? "floating stack" : "fixed stack");
4325 }
4327 if (UseNUMA) {
4328 if (!Linux::libnuma_init()) {
4329 UseNUMA = false;
4330 } else {
4331 if ((Linux::numa_max_node() < 1)) {
4332 // There's only one node(they start from 0), disable NUMA.
4333 UseNUMA = false;
4334 }
4335 }
4336 // With SHM large pages we cannot uncommit a page, so there's not way
4337 // we can make the adaptive lgrp chunk resizing work. If the user specified
4338 // both UseNUMA and UseLargePages (or UseSHM) on the command line - warn and
4339 // disable adaptive resizing.
4340 if (UseNUMA && UseLargePages && UseSHM) {
4341 if (!FLAG_IS_DEFAULT(UseNUMA)) {
4342 if (FLAG_IS_DEFAULT(UseLargePages) && FLAG_IS_DEFAULT(UseSHM)) {
4343 UseLargePages = false;
4344 } else {
4345 warning("UseNUMA is not fully compatible with SHM large pages, disabling adaptive resizing");
4346 UseAdaptiveSizePolicy = false;
4347 UseAdaptiveNUMAChunkSizing = false;
4348 }
4349 } else {
4350 UseNUMA = false;
4351 }
4352 }
4353 if (!UseNUMA && ForceNUMA) {
4354 UseNUMA = true;
4355 }
4356 }
4358 if (MaxFDLimit) {
4359 // set the number of file descriptors to max. print out error
4360 // if getrlimit/setrlimit fails but continue regardless.
4361 struct rlimit nbr_files;
4362 int status = getrlimit(RLIMIT_NOFILE, &nbr_files);
4363 if (status != 0) {
4364 if (PrintMiscellaneous && (Verbose || WizardMode))
4365 perror("os::init_2 getrlimit failed");
4366 } else {
4367 nbr_files.rlim_cur = nbr_files.rlim_max;
4368 status = setrlimit(RLIMIT_NOFILE, &nbr_files);
4369 if (status != 0) {
4370 if (PrintMiscellaneous && (Verbose || WizardMode))
4371 perror("os::init_2 setrlimit failed");
4372 }
4373 }
4374 }
4376 // Initialize lock used to serialize thread creation (see os::create_thread)
4377 Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false));
4379 // at-exit methods are called in the reverse order of their registration.
4380 // atexit functions are called on return from main or as a result of a
4381 // call to exit(3C). There can be only 32 of these functions registered
4382 // and atexit() does not set errno.
4384 if (PerfAllowAtExitRegistration) {
4385 // only register atexit functions if PerfAllowAtExitRegistration is set.
4386 // atexit functions can be delayed until process exit time, which
4387 // can be problematic for embedded VM situations. Embedded VMs should
4388 // call DestroyJavaVM() to assure that VM resources are released.
4390 // note: perfMemory_exit_helper atexit function may be removed in
4391 // the future if the appropriate cleanup code can be added to the
4392 // VM_Exit VMOperation's doit method.
4393 if (atexit(perfMemory_exit_helper) != 0) {
4394 warning("os::init2 atexit(perfMemory_exit_helper) failed");
4395 }
4396 }
4398 // initialize thread priority policy
4399 prio_init();
4401 return JNI_OK;
4402 }
4404 // this is called at the end of vm_initialization
4405 void os::init_3(void)
4406 {
4407 #ifdef JAVASE_EMBEDDED
4408 // Start the MemNotifyThread
4409 if (LowMemoryProtection) {
4410 MemNotifyThread::start();
4411 }
4412 return;
4413 #endif
4414 }
4416 // Mark the polling page as unreadable
4417 void os::make_polling_page_unreadable(void) {
4418 if( !guard_memory((char*)_polling_page, Linux::page_size()) )
4419 fatal("Could not disable polling page");
4420 };
4422 // Mark the polling page as readable
4423 void os::make_polling_page_readable(void) {
4424 if( !linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) {
4425 fatal("Could not enable polling page");
4426 }
4427 };
4429 int os::active_processor_count() {
4430 // Linux doesn't yet have a (official) notion of processor sets,
4431 // so just return the number of online processors.
4432 int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN);
4433 assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check");
4434 return online_cpus;
4435 }
4437 void os::set_native_thread_name(const char *name) {
4438 // Not yet implemented.
4439 return;
4440 }
4442 bool os::distribute_processes(uint length, uint* distribution) {
4443 // Not yet implemented.
4444 return false;
4445 }
4447 bool os::bind_to_processor(uint processor_id) {
4448 // Not yet implemented.
4449 return false;
4450 }
4452 ///
4454 // Suspends the target using the signal mechanism and then grabs the PC before
4455 // resuming the target. Used by the flat-profiler only
4456 ExtendedPC os::get_thread_pc(Thread* thread) {
4457 // Make sure that it is called by the watcher for the VMThread
4458 assert(Thread::current()->is_Watcher_thread(), "Must be watcher");
4459 assert(thread->is_VM_thread(), "Can only be called for VMThread");
4461 ExtendedPC epc;
4463 OSThread* osthread = thread->osthread();
4464 if (do_suspend(osthread)) {
4465 if (osthread->ucontext() != NULL) {
4466 epc = os::Linux::ucontext_get_pc(osthread->ucontext());
4467 } else {
4468 // NULL context is unexpected, double-check this is the VMThread
4469 guarantee(thread->is_VM_thread(), "can only be called for VMThread");
4470 }
4471 do_resume(osthread);
4472 }
4473 // failure means pthread_kill failed for some reason - arguably this is
4474 // a fatal problem, but such problems are ignored elsewhere
4476 return epc;
4477 }
4479 int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond, pthread_mutex_t *_mutex, const struct timespec *_abstime)
4480 {
4481 if (is_NPTL()) {
4482 return pthread_cond_timedwait(_cond, _mutex, _abstime);
4483 } else {
4484 // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control
4485 // word back to default 64bit precision if condvar is signaled. Java
4486 // wants 53bit precision. Save and restore current value.
4487 int fpu = get_fpu_control_word();
4488 int status = pthread_cond_timedwait(_cond, _mutex, _abstime);
4489 set_fpu_control_word(fpu);
4490 return status;
4491 }
4492 }
4494 ////////////////////////////////////////////////////////////////////////////////
4495 // debug support
4497 bool os::find(address addr, outputStream* st) {
4498 Dl_info dlinfo;
4499 memset(&dlinfo, 0, sizeof(dlinfo));
4500 if (dladdr(addr, &dlinfo)) {
4501 st->print(PTR_FORMAT ": ", addr);
4502 if (dlinfo.dli_sname != NULL) {
4503 st->print("%s+%#x", dlinfo.dli_sname,
4504 addr - (intptr_t)dlinfo.dli_saddr);
4505 } else if (dlinfo.dli_fname) {
4506 st->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase);
4507 } else {
4508 st->print("<absolute address>");
4509 }
4510 if (dlinfo.dli_fname) {
4511 st->print(" in %s", dlinfo.dli_fname);
4512 }
4513 if (dlinfo.dli_fbase) {
4514 st->print(" at " PTR_FORMAT, dlinfo.dli_fbase);
4515 }
4516 st->cr();
4518 if (Verbose) {
4519 // decode some bytes around the PC
4520 address begin = clamp_address_in_page(addr-40, addr, os::vm_page_size());
4521 address end = clamp_address_in_page(addr+40, addr, os::vm_page_size());
4522 address lowest = (address) dlinfo.dli_sname;
4523 if (!lowest) lowest = (address) dlinfo.dli_fbase;
4524 if (begin < lowest) begin = lowest;
4525 Dl_info dlinfo2;
4526 if (dladdr(end, &dlinfo2) && dlinfo2.dli_saddr != dlinfo.dli_saddr
4527 && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin)
4528 end = (address) dlinfo2.dli_saddr;
4529 Disassembler::decode(begin, end, st);
4530 }
4531 return true;
4532 }
4533 return false;
4534 }
4536 ////////////////////////////////////////////////////////////////////////////////
4537 // misc
4539 // This does not do anything on Linux. This is basically a hook for being
4540 // able to use structured exception handling (thread-local exception filters)
4541 // on, e.g., Win32.
4542 void
4543 os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method,
4544 JavaCallArguments* args, Thread* thread) {
4545 f(value, method, args, thread);
4546 }
4548 void os::print_statistics() {
4549 }
4551 int os::message_box(const char* title, const char* message) {
4552 int i;
4553 fdStream err(defaultStream::error_fd());
4554 for (i = 0; i < 78; i++) err.print_raw("=");
4555 err.cr();
4556 err.print_raw_cr(title);
4557 for (i = 0; i < 78; i++) err.print_raw("-");
4558 err.cr();
4559 err.print_raw_cr(message);
4560 for (i = 0; i < 78; i++) err.print_raw("=");
4561 err.cr();
4563 char buf[16];
4564 // Prevent process from exiting upon "read error" without consuming all CPU
4565 while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); }
4567 return buf[0] == 'y' || buf[0] == 'Y';
4568 }
4570 int os::stat(const char *path, struct stat *sbuf) {
4571 char pathbuf[MAX_PATH];
4572 if (strlen(path) > MAX_PATH - 1) {
4573 errno = ENAMETOOLONG;
4574 return -1;
4575 }
4576 os::native_path(strcpy(pathbuf, path));
4577 return ::stat(pathbuf, sbuf);
4578 }
4580 bool os::check_heap(bool force) {
4581 return true;
4582 }
4584 int local_vsnprintf(char* buf, size_t count, const char* format, va_list args) {
4585 return ::vsnprintf(buf, count, format, args);
4586 }
4588 // Is a (classpath) directory empty?
4589 bool os::dir_is_empty(const char* path) {
4590 DIR *dir = NULL;
4591 struct dirent *ptr;
4593 dir = opendir(path);
4594 if (dir == NULL) return true;
4596 /* Scan the directory */
4597 bool result = true;
4598 char buf[sizeof(struct dirent) + MAX_PATH];
4599 while (result && (ptr = ::readdir(dir)) != NULL) {
4600 if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) {
4601 result = false;
4602 }
4603 }
4604 closedir(dir);
4605 return result;
4606 }
4608 // This code originates from JDK's sysOpen and open64_w
4609 // from src/solaris/hpi/src/system_md.c
4611 #ifndef O_DELETE
4612 #define O_DELETE 0x10000
4613 #endif
4615 // Open a file. Unlink the file immediately after open returns
4616 // if the specified oflag has the O_DELETE flag set.
4617 // O_DELETE is used only in j2se/src/share/native/java/util/zip/ZipFile.c
4619 int os::open(const char *path, int oflag, int mode) {
4621 if (strlen(path) > MAX_PATH - 1) {
4622 errno = ENAMETOOLONG;
4623 return -1;
4624 }
4625 int fd;
4626 int o_delete = (oflag & O_DELETE);
4627 oflag = oflag & ~O_DELETE;
4629 fd = ::open64(path, oflag, mode);
4630 if (fd == -1) return -1;
4632 //If the open succeeded, the file might still be a directory
4633 {
4634 struct stat64 buf64;
4635 int ret = ::fstat64(fd, &buf64);
4636 int st_mode = buf64.st_mode;
4638 if (ret != -1) {
4639 if ((st_mode & S_IFMT) == S_IFDIR) {
4640 errno = EISDIR;
4641 ::close(fd);
4642 return -1;
4643 }
4644 } else {
4645 ::close(fd);
4646 return -1;
4647 }
4648 }
4650 /*
4651 * All file descriptors that are opened in the JVM and not
4652 * specifically destined for a subprocess should have the
4653 * close-on-exec flag set. If we don't set it, then careless 3rd
4654 * party native code might fork and exec without closing all
4655 * appropriate file descriptors (e.g. as we do in closeDescriptors in
4656 * UNIXProcess.c), and this in turn might:
4657 *
4658 * - cause end-of-file to fail to be detected on some file
4659 * descriptors, resulting in mysterious hangs, or
4660 *
4661 * - might cause an fopen in the subprocess to fail on a system
4662 * suffering from bug 1085341.
4663 *
4664 * (Yes, the default setting of the close-on-exec flag is a Unix
4665 * design flaw)
4666 *
4667 * See:
4668 * 1085341: 32-bit stdio routines should support file descriptors >255
4669 * 4843136: (process) pipe file descriptor from Runtime.exec not being closed
4670 * 6339493: (process) Runtime.exec does not close all file descriptors on Solaris 9
4671 */
4672 #ifdef FD_CLOEXEC
4673 {
4674 int flags = ::fcntl(fd, F_GETFD);
4675 if (flags != -1)
4676 ::fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
4677 }
4678 #endif
4680 if (o_delete != 0) {
4681 ::unlink(path);
4682 }
4683 return fd;
4684 }
4687 // create binary file, rewriting existing file if required
4688 int os::create_binary_file(const char* path, bool rewrite_existing) {
4689 int oflags = O_WRONLY | O_CREAT;
4690 if (!rewrite_existing) {
4691 oflags |= O_EXCL;
4692 }
4693 return ::open64(path, oflags, S_IREAD | S_IWRITE);
4694 }
4696 // return current position of file pointer
4697 jlong os::current_file_offset(int fd) {
4698 return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR);
4699 }
4701 // move file pointer to the specified offset
4702 jlong os::seek_to_file_offset(int fd, jlong offset) {
4703 return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET);
4704 }
4706 // This code originates from JDK's sysAvailable
4707 // from src/solaris/hpi/src/native_threads/src/sys_api_td.c
4709 int os::available(int fd, jlong *bytes) {
4710 jlong cur, end;
4711 int mode;
4712 struct stat64 buf64;
4714 if (::fstat64(fd, &buf64) >= 0) {
4715 mode = buf64.st_mode;
4716 if (S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) {
4717 /*
4718 * XXX: is the following call interruptible? If so, this might
4719 * need to go through the INTERRUPT_IO() wrapper as for other
4720 * blocking, interruptible calls in this file.
4721 */
4722 int n;
4723 if (::ioctl(fd, FIONREAD, &n) >= 0) {
4724 *bytes = n;
4725 return 1;
4726 }
4727 }
4728 }
4729 if ((cur = ::lseek64(fd, 0L, SEEK_CUR)) == -1) {
4730 return 0;
4731 } else if ((end = ::lseek64(fd, 0L, SEEK_END)) == -1) {
4732 return 0;
4733 } else if (::lseek64(fd, cur, SEEK_SET) == -1) {
4734 return 0;
4735 }
4736 *bytes = end - cur;
4737 return 1;
4738 }
4740 int os::socket_available(int fd, jint *pbytes) {
4741 // Linux doc says EINTR not returned, unlike Solaris
4742 int ret = ::ioctl(fd, FIONREAD, pbytes);
4744 //%% note ioctl can return 0 when successful, JVM_SocketAvailable
4745 // is expected to return 0 on failure and 1 on success to the jdk.
4746 return (ret < 0) ? 0 : 1;
4747 }
4749 // Map a block of memory.
4750 char* os::pd_map_memory(int fd, const char* file_name, size_t file_offset,
4751 char *addr, size_t bytes, bool read_only,
4752 bool allow_exec) {
4753 int prot;
4754 int flags = MAP_PRIVATE;
4756 if (read_only) {
4757 prot = PROT_READ;
4758 } else {
4759 prot = PROT_READ | PROT_WRITE;
4760 }
4762 if (allow_exec) {
4763 prot |= PROT_EXEC;
4764 }
4766 if (addr != NULL) {
4767 flags |= MAP_FIXED;
4768 }
4770 char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags,
4771 fd, file_offset);
4772 if (mapped_address == MAP_FAILED) {
4773 return NULL;
4774 }
4775 return mapped_address;
4776 }
4779 // Remap a block of memory.
4780 char* os::pd_remap_memory(int fd, const char* file_name, size_t file_offset,
4781 char *addr, size_t bytes, bool read_only,
4782 bool allow_exec) {
4783 // same as map_memory() on this OS
4784 return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only,
4785 allow_exec);
4786 }
4789 // Unmap a block of memory.
4790 bool os::pd_unmap_memory(char* addr, size_t bytes) {
4791 return munmap(addr, bytes) == 0;
4792 }
4794 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time);
4796 static clockid_t thread_cpu_clockid(Thread* thread) {
4797 pthread_t tid = thread->osthread()->pthread_id();
4798 clockid_t clockid;
4800 // Get thread clockid
4801 int rc = os::Linux::pthread_getcpuclockid(tid, &clockid);
4802 assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code");
4803 return clockid;
4804 }
4806 // current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool)
4807 // are used by JVM M&M and JVMTI to get user+sys or user CPU time
4808 // of a thread.
4809 //
4810 // current_thread_cpu_time() and thread_cpu_time(Thread*) returns
4811 // the fast estimate available on the platform.
4813 jlong os::current_thread_cpu_time() {
4814 if (os::Linux::supports_fast_thread_cpu_time()) {
4815 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
4816 } else {
4817 // return user + sys since the cost is the same
4818 return slow_thread_cpu_time(Thread::current(), true /* user + sys */);
4819 }
4820 }
4822 jlong os::thread_cpu_time(Thread* thread) {
4823 // consistent with what current_thread_cpu_time() returns
4824 if (os::Linux::supports_fast_thread_cpu_time()) {
4825 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread));
4826 } else {
4827 return slow_thread_cpu_time(thread, true /* user + sys */);
4828 }
4829 }
4831 jlong os::current_thread_cpu_time(bool user_sys_cpu_time) {
4832 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
4833 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
4834 } else {
4835 return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time);
4836 }
4837 }
4839 jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
4840 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
4841 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread));
4842 } else {
4843 return slow_thread_cpu_time(thread, user_sys_cpu_time);
4844 }
4845 }
4847 //
4848 // -1 on error.
4849 //
4851 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
4852 static bool proc_task_unchecked = true;
4853 static const char *proc_stat_path = "/proc/%d/stat";
4854 pid_t tid = thread->osthread()->thread_id();
4855 char *s;
4856 char stat[2048];
4857 int statlen;
4858 char proc_name[64];
4859 int count;
4860 long sys_time, user_time;
4861 char cdummy;
4862 int idummy;
4863 long ldummy;
4864 FILE *fp;
4866 // The /proc/<tid>/stat aggregates per-process usage on
4867 // new Linux kernels 2.6+ where NPTL is supported.
4868 // The /proc/self/task/<tid>/stat still has the per-thread usage.
4869 // See bug 6328462.
4870 // There possibly can be cases where there is no directory
4871 // /proc/self/task, so we check its availability.
4872 if (proc_task_unchecked && os::Linux::is_NPTL()) {
4873 // This is executed only once
4874 proc_task_unchecked = false;
4875 fp = fopen("/proc/self/task", "r");
4876 if (fp != NULL) {
4877 proc_stat_path = "/proc/self/task/%d/stat";
4878 fclose(fp);
4879 }
4880 }
4882 sprintf(proc_name, proc_stat_path, tid);
4883 fp = fopen(proc_name, "r");
4884 if ( fp == NULL ) return -1;
4885 statlen = fread(stat, 1, 2047, fp);
4886 stat[statlen] = '\0';
4887 fclose(fp);
4889 // Skip pid and the command string. Note that we could be dealing with
4890 // weird command names, e.g. user could decide to rename java launcher
4891 // to "java 1.4.2 :)", then the stat file would look like
4892 // 1234 (java 1.4.2 :)) R ... ...
4893 // We don't really need to know the command string, just find the last
4894 // occurrence of ")" and then start parsing from there. See bug 4726580.
4895 s = strrchr(stat, ')');
4896 if (s == NULL ) return -1;
4898 // Skip blank chars
4899 do s++; while (isspace(*s));
4901 count = sscanf(s,"%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu",
4902 &cdummy, &idummy, &idummy, &idummy, &idummy, &idummy,
4903 &ldummy, &ldummy, &ldummy, &ldummy, &ldummy,
4904 &user_time, &sys_time);
4905 if ( count != 13 ) return -1;
4906 if (user_sys_cpu_time) {
4907 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec);
4908 } else {
4909 return (jlong)user_time * (1000000000 / clock_tics_per_sec);
4910 }
4911 }
4913 void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
4914 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits
4915 info_ptr->may_skip_backward = false; // elapsed time not wall time
4916 info_ptr->may_skip_forward = false; // elapsed time not wall time
4917 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned
4918 }
4920 void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
4921 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits
4922 info_ptr->may_skip_backward = false; // elapsed time not wall time
4923 info_ptr->may_skip_forward = false; // elapsed time not wall time
4924 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned
4925 }
4927 bool os::is_thread_cpu_time_supported() {
4928 return true;
4929 }
4931 // System loadavg support. Returns -1 if load average cannot be obtained.
4932 // Linux doesn't yet have a (official) notion of processor sets,
4933 // so just return the system wide load average.
4934 int os::loadavg(double loadavg[], int nelem) {
4935 return ::getloadavg(loadavg, nelem);
4936 }
4938 void os::pause() {
4939 char filename[MAX_PATH];
4940 if (PauseAtStartupFile && PauseAtStartupFile[0]) {
4941 jio_snprintf(filename, MAX_PATH, PauseAtStartupFile);
4942 } else {
4943 jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id());
4944 }
4946 int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
4947 if (fd != -1) {
4948 struct stat buf;
4949 ::close(fd);
4950 while (::stat(filename, &buf) == 0) {
4951 (void)::poll(NULL, 0, 100);
4952 }
4953 } else {
4954 jio_fprintf(stderr,
4955 "Could not open pause file '%s', continuing immediately.\n", filename);
4956 }
4957 }
4960 // Refer to the comments in os_solaris.cpp park-unpark.
4961 //
4962 // Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can
4963 // hang indefinitely. For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable.
4964 // For specifics regarding the bug see GLIBC BUGID 261237 :
4965 // http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html.
4966 // Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future
4967 // will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar
4968 // is used. (The simple C test-case provided in the GLIBC bug report manifests the
4969 // hang). The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos()
4970 // and monitorenter when we're using 1-0 locking. All those operations may result in
4971 // calls to pthread_cond_timedwait(). Using LD_ASSUME_KERNEL to use an older version
4972 // of libpthread avoids the problem, but isn't practical.
4973 //
4974 // Possible remedies:
4975 //
4976 // 1. Establish a minimum relative wait time. 50 to 100 msecs seems to work.
4977 // This is palliative and probabilistic, however. If the thread is preempted
4978 // between the call to compute_abstime() and pthread_cond_timedwait(), more
4979 // than the minimum period may have passed, and the abstime may be stale (in the
4980 // past) resultin in a hang. Using this technique reduces the odds of a hang
4981 // but the JVM is still vulnerable, particularly on heavily loaded systems.
4982 //
4983 // 2. Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead
4984 // of the usual flag-condvar-mutex idiom. The write side of the pipe is set
4985 // NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo)
4986 // reduces to poll()+read(). This works well, but consumes 2 FDs per extant
4987 // thread.
4988 //
4989 // 3. Embargo pthread_cond_timedwait() and implement a native "chron" thread
4990 // that manages timeouts. We'd emulate pthread_cond_timedwait() by enqueuing
4991 // a timeout request to the chron thread and then blocking via pthread_cond_wait().
4992 // This also works well. In fact it avoids kernel-level scalability impediments
4993 // on certain platforms that don't handle lots of active pthread_cond_timedwait()
4994 // timers in a graceful fashion.
4995 //
4996 // 4. When the abstime value is in the past it appears that control returns
4997 // correctly from pthread_cond_timedwait(), but the condvar is left corrupt.
4998 // Subsequent timedwait/wait calls may hang indefinitely. Given that, we
4999 // can avoid the problem by reinitializing the condvar -- by cond_destroy()
5000 // followed by cond_init() -- after all calls to pthread_cond_timedwait().
5001 // It may be possible to avoid reinitialization by checking the return
5002 // value from pthread_cond_timedwait(). In addition to reinitializing the
5003 // condvar we must establish the invariant that cond_signal() is only called
5004 // within critical sections protected by the adjunct mutex. This prevents
5005 // cond_signal() from "seeing" a condvar that's in the midst of being
5006 // reinitialized or that is corrupt. Sadly, this invariant obviates the
5007 // desirable signal-after-unlock optimization that avoids futile context switching.
5008 //
5009 // I'm also concerned that some versions of NTPL might allocate an auxilliary
5010 // structure when a condvar is used or initialized. cond_destroy() would
5011 // release the helper structure. Our reinitialize-after-timedwait fix
5012 // put excessive stress on malloc/free and locks protecting the c-heap.
5013 //
5014 // We currently use (4). See the WorkAroundNTPLTimedWaitHang flag.
5015 // It may be possible to refine (4) by checking the kernel and NTPL verisons
5016 // and only enabling the work-around for vulnerable environments.
5018 // utility to compute the abstime argument to timedwait:
5019 // millis is the relative timeout time
5020 // abstime will be the absolute timeout time
5021 // TODO: replace compute_abstime() with unpackTime()
5023 static struct timespec* compute_abstime(timespec* abstime, jlong millis) {
5024 if (millis < 0) millis = 0;
5025 struct timeval now;
5026 int status = gettimeofday(&now, NULL);
5027 assert(status == 0, "gettimeofday");
5028 jlong seconds = millis / 1000;
5029 millis %= 1000;
5030 if (seconds > 50000000) { // see man cond_timedwait(3T)
5031 seconds = 50000000;
5032 }
5033 abstime->tv_sec = now.tv_sec + seconds;
5034 long usec = now.tv_usec + millis * 1000;
5035 if (usec >= 1000000) {
5036 abstime->tv_sec += 1;
5037 usec -= 1000000;
5038 }
5039 abstime->tv_nsec = usec * 1000;
5040 return abstime;
5041 }
5044 // Test-and-clear _Event, always leaves _Event set to 0, returns immediately.
5045 // Conceptually TryPark() should be equivalent to park(0).
5047 int os::PlatformEvent::TryPark() {
5048 for (;;) {
5049 const int v = _Event ;
5050 guarantee ((v == 0) || (v == 1), "invariant") ;
5051 if (Atomic::cmpxchg (0, &_Event, v) == v) return v ;
5052 }
5053 }
5055 void os::PlatformEvent::park() { // AKA "down()"
5056 // Invariant: Only the thread associated with the Event/PlatformEvent
5057 // may call park().
5058 // TODO: assert that _Assoc != NULL or _Assoc == Self
5059 int v ;
5060 for (;;) {
5061 v = _Event ;
5062 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ;
5063 }
5064 guarantee (v >= 0, "invariant") ;
5065 if (v == 0) {
5066 // Do this the hard way by blocking ...
5067 int status = pthread_mutex_lock(_mutex);
5068 assert_status(status == 0, status, "mutex_lock");
5069 guarantee (_nParked == 0, "invariant") ;
5070 ++ _nParked ;
5071 while (_Event < 0) {
5072 status = pthread_cond_wait(_cond, _mutex);
5073 // for some reason, under 2.7 lwp_cond_wait() may return ETIME ...
5074 // Treat this the same as if the wait was interrupted
5075 if (status == ETIME) { status = EINTR; }
5076 assert_status(status == 0 || status == EINTR, status, "cond_wait");
5077 }
5078 -- _nParked ;
5080 _Event = 0 ;
5081 status = pthread_mutex_unlock(_mutex);
5082 assert_status(status == 0, status, "mutex_unlock");
5083 // Paranoia to ensure our locked and lock-free paths interact
5084 // correctly with each other.
5085 OrderAccess::fence();
5086 }
5087 guarantee (_Event >= 0, "invariant") ;
5088 }
5090 int os::PlatformEvent::park(jlong millis) {
5091 guarantee (_nParked == 0, "invariant") ;
5093 int v ;
5094 for (;;) {
5095 v = _Event ;
5096 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ;
5097 }
5098 guarantee (v >= 0, "invariant") ;
5099 if (v != 0) return OS_OK ;
5101 // We do this the hard way, by blocking the thread.
5102 // Consider enforcing a minimum timeout value.
5103 struct timespec abst;
5104 compute_abstime(&abst, millis);
5106 int ret = OS_TIMEOUT;
5107 int status = pthread_mutex_lock(_mutex);
5108 assert_status(status == 0, status, "mutex_lock");
5109 guarantee (_nParked == 0, "invariant") ;
5110 ++_nParked ;
5112 // Object.wait(timo) will return because of
5113 // (a) notification
5114 // (b) timeout
5115 // (c) thread.interrupt
5116 //
5117 // Thread.interrupt and object.notify{All} both call Event::set.
5118 // That is, we treat thread.interrupt as a special case of notification.
5119 // The underlying Solaris implementation, cond_timedwait, admits
5120 // spurious/premature wakeups, but the JLS/JVM spec prevents the
5121 // JVM from making those visible to Java code. As such, we must
5122 // filter out spurious wakeups. We assume all ETIME returns are valid.
5123 //
5124 // TODO: properly differentiate simultaneous notify+interrupt.
5125 // In that case, we should propagate the notify to another waiter.
5127 while (_Event < 0) {
5128 status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst);
5129 if (status != 0 && WorkAroundNPTLTimedWaitHang) {
5130 pthread_cond_destroy (_cond);
5131 pthread_cond_init (_cond, NULL) ;
5132 }
5133 assert_status(status == 0 || status == EINTR ||
5134 status == ETIME || status == ETIMEDOUT,
5135 status, "cond_timedwait");
5136 if (!FilterSpuriousWakeups) break ; // previous semantics
5137 if (status == ETIME || status == ETIMEDOUT) break ;
5138 // We consume and ignore EINTR and spurious wakeups.
5139 }
5140 --_nParked ;
5141 if (_Event >= 0) {
5142 ret = OS_OK;
5143 }
5144 _Event = 0 ;
5145 status = pthread_mutex_unlock(_mutex);
5146 assert_status(status == 0, status, "mutex_unlock");
5147 assert (_nParked == 0, "invariant") ;
5148 // Paranoia to ensure our locked and lock-free paths interact
5149 // correctly with each other.
5150 OrderAccess::fence();
5151 return ret;
5152 }
5154 void os::PlatformEvent::unpark() {
5155 // Transitions for _Event:
5156 // 0 :=> 1
5157 // 1 :=> 1
5158 // -1 :=> either 0 or 1; must signal target thread
5159 // That is, we can safely transition _Event from -1 to either
5160 // 0 or 1. Forcing 1 is slightly more efficient for back-to-back
5161 // unpark() calls.
5162 // See also: "Semaphores in Plan 9" by Mullender & Cox
5163 //
5164 // Note: Forcing a transition from "-1" to "1" on an unpark() means
5165 // that it will take two back-to-back park() calls for the owning
5166 // thread to block. This has the benefit of forcing a spurious return
5167 // from the first park() call after an unpark() call which will help
5168 // shake out uses of park() and unpark() without condition variables.
5170 if (Atomic::xchg(1, &_Event) >= 0) return;
5172 // Wait for the thread associated with the event to vacate
5173 int status = pthread_mutex_lock(_mutex);
5174 assert_status(status == 0, status, "mutex_lock");
5175 int AnyWaiters = _nParked;
5176 assert(AnyWaiters == 0 || AnyWaiters == 1, "invariant");
5177 if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) {
5178 AnyWaiters = 0;
5179 pthread_cond_signal(_cond);
5180 }
5181 status = pthread_mutex_unlock(_mutex);
5182 assert_status(status == 0, status, "mutex_unlock");
5183 if (AnyWaiters != 0) {
5184 status = pthread_cond_signal(_cond);
5185 assert_status(status == 0, status, "cond_signal");
5186 }
5188 // Note that we signal() _after dropping the lock for "immortal" Events.
5189 // This is safe and avoids a common class of futile wakeups. In rare
5190 // circumstances this can cause a thread to return prematurely from
5191 // cond_{timed}wait() but the spurious wakeup is benign and the victim will
5192 // simply re-test the condition and re-park itself.
5193 }
5196 // JSR166
5197 // -------------------------------------------------------
5199 /*
5200 * The solaris and linux implementations of park/unpark are fairly
5201 * conservative for now, but can be improved. They currently use a
5202 * mutex/condvar pair, plus a a count.
5203 * Park decrements count if > 0, else does a condvar wait. Unpark
5204 * sets count to 1 and signals condvar. Only one thread ever waits
5205 * on the condvar. Contention seen when trying to park implies that someone
5206 * is unparking you, so don't wait. And spurious returns are fine, so there
5207 * is no need to track notifications.
5208 */
5210 #define MAX_SECS 100000000
5211 /*
5212 * This code is common to linux and solaris and will be moved to a
5213 * common place in dolphin.
5214 *
5215 * The passed in time value is either a relative time in nanoseconds
5216 * or an absolute time in milliseconds. Either way it has to be unpacked
5217 * into suitable seconds and nanoseconds components and stored in the
5218 * given timespec structure.
5219 * Given time is a 64-bit value and the time_t used in the timespec is only
5220 * a signed-32-bit value (except on 64-bit Linux) we have to watch for
5221 * overflow if times way in the future are given. Further on Solaris versions
5222 * prior to 10 there is a restriction (see cond_timedwait) that the specified
5223 * number of seconds, in abstime, is less than current_time + 100,000,000.
5224 * As it will be 28 years before "now + 100000000" will overflow we can
5225 * ignore overflow and just impose a hard-limit on seconds using the value
5226 * of "now + 100,000,000". This places a limit on the timeout of about 3.17
5227 * years from "now".
5228 */
5230 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) {
5231 assert (time > 0, "convertTime");
5233 struct timeval now;
5234 int status = gettimeofday(&now, NULL);
5235 assert(status == 0, "gettimeofday");
5237 time_t max_secs = now.tv_sec + MAX_SECS;
5239 if (isAbsolute) {
5240 jlong secs = time / 1000;
5241 if (secs > max_secs) {
5242 absTime->tv_sec = max_secs;
5243 }
5244 else {
5245 absTime->tv_sec = secs;
5246 }
5247 absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC;
5248 }
5249 else {
5250 jlong secs = time / NANOSECS_PER_SEC;
5251 if (secs >= MAX_SECS) {
5252 absTime->tv_sec = max_secs;
5253 absTime->tv_nsec = 0;
5254 }
5255 else {
5256 absTime->tv_sec = now.tv_sec + secs;
5257 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000;
5258 if (absTime->tv_nsec >= NANOSECS_PER_SEC) {
5259 absTime->tv_nsec -= NANOSECS_PER_SEC;
5260 ++absTime->tv_sec; // note: this must be <= max_secs
5261 }
5262 }
5263 }
5264 assert(absTime->tv_sec >= 0, "tv_sec < 0");
5265 assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs");
5266 assert(absTime->tv_nsec >= 0, "tv_nsec < 0");
5267 assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec");
5268 }
5270 void Parker::park(bool isAbsolute, jlong time) {
5271 // Ideally we'd do something useful while spinning, such
5272 // as calling unpackTime().
5274 // Optional fast-path check:
5275 // Return immediately if a permit is available.
5276 // We depend on Atomic::xchg() having full barrier semantics
5277 // since we are doing a lock-free update to _counter.
5278 if (Atomic::xchg(0, &_counter) > 0) return;
5280 Thread* thread = Thread::current();
5281 assert(thread->is_Java_thread(), "Must be JavaThread");
5282 JavaThread *jt = (JavaThread *)thread;
5284 // Optional optimization -- avoid state transitions if there's an interrupt pending.
5285 // Check interrupt before trying to wait
5286 if (Thread::is_interrupted(thread, false)) {
5287 return;
5288 }
5290 // Next, demultiplex/decode time arguments
5291 timespec absTime;
5292 if (time < 0 || (isAbsolute && time == 0) ) { // don't wait at all
5293 return;
5294 }
5295 if (time > 0) {
5296 unpackTime(&absTime, isAbsolute, time);
5297 }
5300 // Enter safepoint region
5301 // Beware of deadlocks such as 6317397.
5302 // The per-thread Parker:: mutex is a classic leaf-lock.
5303 // In particular a thread must never block on the Threads_lock while
5304 // holding the Parker:: mutex. If safepoints are pending both the
5305 // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock.
5306 ThreadBlockInVM tbivm(jt);
5308 // Don't wait if cannot get lock since interference arises from
5309 // unblocking. Also. check interrupt before trying wait
5310 if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) {
5311 return;
5312 }
5314 int status ;
5315 if (_counter > 0) { // no wait needed
5316 _counter = 0;
5317 status = pthread_mutex_unlock(_mutex);
5318 assert (status == 0, "invariant") ;
5319 // Paranoia to ensure our locked and lock-free paths interact
5320 // correctly with each other and Java-level accesses.
5321 OrderAccess::fence();
5322 return;
5323 }
5325 #ifdef ASSERT
5326 // Don't catch signals while blocked; let the running threads have the signals.
5327 // (This allows a debugger to break into the running thread.)
5328 sigset_t oldsigs;
5329 sigset_t* allowdebug_blocked = os::Linux::allowdebug_blocked_signals();
5330 pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs);
5331 #endif
5333 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */);
5334 jt->set_suspend_equivalent();
5335 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
5337 if (time == 0) {
5338 status = pthread_cond_wait (_cond, _mutex) ;
5339 } else {
5340 status = os::Linux::safe_cond_timedwait (_cond, _mutex, &absTime) ;
5341 if (status != 0 && WorkAroundNPTLTimedWaitHang) {
5342 pthread_cond_destroy (_cond) ;
5343 pthread_cond_init (_cond, NULL);
5344 }
5345 }
5346 assert_status(status == 0 || status == EINTR ||
5347 status == ETIME || status == ETIMEDOUT,
5348 status, "cond_timedwait");
5350 #ifdef ASSERT
5351 pthread_sigmask(SIG_SETMASK, &oldsigs, NULL);
5352 #endif
5354 _counter = 0 ;
5355 status = pthread_mutex_unlock(_mutex) ;
5356 assert_status(status == 0, status, "invariant") ;
5357 // Paranoia to ensure our locked and lock-free paths interact
5358 // correctly with each other and Java-level accesses.
5359 OrderAccess::fence();
5361 // If externally suspended while waiting, re-suspend
5362 if (jt->handle_special_suspend_equivalent_condition()) {
5363 jt->java_suspend_self();
5364 }
5365 }
5367 void Parker::unpark() {
5368 int s, status ;
5369 status = pthread_mutex_lock(_mutex);
5370 assert (status == 0, "invariant") ;
5371 s = _counter;
5372 _counter = 1;
5373 if (s < 1) {
5374 if (WorkAroundNPTLTimedWaitHang) {
5375 status = pthread_cond_signal (_cond) ;
5376 assert (status == 0, "invariant") ;
5377 status = pthread_mutex_unlock(_mutex);
5378 assert (status == 0, "invariant") ;
5379 } else {
5380 status = pthread_mutex_unlock(_mutex);
5381 assert (status == 0, "invariant") ;
5382 status = pthread_cond_signal (_cond) ;
5383 assert (status == 0, "invariant") ;
5384 }
5385 } else {
5386 pthread_mutex_unlock(_mutex);
5387 assert (status == 0, "invariant") ;
5388 }
5389 }
5392 extern char** environ;
5394 #ifndef __NR_fork
5395 #define __NR_fork IA32_ONLY(2) IA64_ONLY(not defined) AMD64_ONLY(57)
5396 #endif
5398 #ifndef __NR_execve
5399 #define __NR_execve IA32_ONLY(11) IA64_ONLY(1033) AMD64_ONLY(59)
5400 #endif
5402 // Run the specified command in a separate process. Return its exit value,
5403 // or -1 on failure (e.g. can't fork a new process).
5404 // Unlike system(), this function can be called from signal handler. It
5405 // doesn't block SIGINT et al.
5406 int os::fork_and_exec(char* cmd) {
5407 const char * argv[4] = {"sh", "-c", cmd, NULL};
5409 // fork() in LinuxThreads/NPTL is not async-safe. It needs to run
5410 // pthread_atfork handlers and reset pthread library. All we need is a
5411 // separate process to execve. Make a direct syscall to fork process.
5412 // On IA64 there's no fork syscall, we have to use fork() and hope for
5413 // the best...
5414 pid_t pid = NOT_IA64(syscall(__NR_fork);)
5415 IA64_ONLY(fork();)
5417 if (pid < 0) {
5418 // fork failed
5419 return -1;
5421 } else if (pid == 0) {
5422 // child process
5424 // execve() in LinuxThreads will call pthread_kill_other_threads_np()
5425 // first to kill every thread on the thread list. Because this list is
5426 // not reset by fork() (see notes above), execve() will instead kill
5427 // every thread in the parent process. We know this is the only thread
5428 // in the new process, so make a system call directly.
5429 // IA64 should use normal execve() from glibc to match the glibc fork()
5430 // above.
5431 NOT_IA64(syscall(__NR_execve, "/bin/sh", argv, environ);)
5432 IA64_ONLY(execve("/bin/sh", (char* const*)argv, environ);)
5434 // execve failed
5435 _exit(-1);
5437 } else {
5438 // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't
5439 // care about the actual exit code, for now.
5441 int status;
5443 // Wait for the child process to exit. This returns immediately if
5444 // the child has already exited. */
5445 while (waitpid(pid, &status, 0) < 0) {
5446 switch (errno) {
5447 case ECHILD: return 0;
5448 case EINTR: break;
5449 default: return -1;
5450 }
5451 }
5453 if (WIFEXITED(status)) {
5454 // The child exited normally; get its exit code.
5455 return WEXITSTATUS(status);
5456 } else if (WIFSIGNALED(status)) {
5457 // The child exited because of a signal
5458 // The best value to return is 0x80 + signal number,
5459 // because that is what all Unix shells do, and because
5460 // it allows callers to distinguish between process exit and
5461 // process death by signal.
5462 return 0x80 + WTERMSIG(status);
5463 } else {
5464 // Unknown exit code; pass it through
5465 return status;
5466 }
5467 }
5468 }
5470 // is_headless_jre()
5471 //
5472 // Test for the existence of xawt/libmawt.so or libawt_xawt.so
5473 // in order to report if we are running in a headless jre
5474 //
5475 // Since JDK8 xawt/libmawt.so was moved into the same directory
5476 // as libawt.so, and renamed libawt_xawt.so
5477 //
5478 bool os::is_headless_jre() {
5479 struct stat statbuf;
5480 char buf[MAXPATHLEN];
5481 char libmawtpath[MAXPATHLEN];
5482 const char *xawtstr = "/xawt/libmawt.so";
5483 const char *new_xawtstr = "/libawt_xawt.so";
5484 char *p;
5486 // Get path to libjvm.so
5487 os::jvm_path(buf, sizeof(buf));
5489 // Get rid of libjvm.so
5490 p = strrchr(buf, '/');
5491 if (p == NULL) return false;
5492 else *p = '\0';
5494 // Get rid of client or server
5495 p = strrchr(buf, '/');
5496 if (p == NULL) return false;
5497 else *p = '\0';
5499 // check xawt/libmawt.so
5500 strcpy(libmawtpath, buf);
5501 strcat(libmawtpath, xawtstr);
5502 if (::stat(libmawtpath, &statbuf) == 0) return false;
5504 // check libawt_xawt.so
5505 strcpy(libmawtpath, buf);
5506 strcat(libmawtpath, new_xawtstr);
5507 if (::stat(libmawtpath, &statbuf) == 0) return false;
5509 return true;
5510 }
5512 // Get the default path to the core file
5513 // Returns the length of the string
5514 int os::get_core_path(char* buffer, size_t bufferSize) {
5515 const char* p = get_current_directory(buffer, bufferSize);
5517 if (p == NULL) {
5518 assert(p != NULL, "failed to get current directory");
5519 return 0;
5520 }
5522 return strlen(buffer);
5523 }
5525 #ifdef JAVASE_EMBEDDED
5526 //
5527 // A thread to watch the '/dev/mem_notify' device, which will tell us when the OS is running low on memory.
5528 //
5529 MemNotifyThread* MemNotifyThread::_memnotify_thread = NULL;
5531 // ctor
5532 //
5533 MemNotifyThread::MemNotifyThread(int fd): Thread() {
5534 assert(memnotify_thread() == NULL, "we can only allocate one MemNotifyThread");
5535 _fd = fd;
5537 if (os::create_thread(this, os::os_thread)) {
5538 _memnotify_thread = this;
5539 os::set_priority(this, NearMaxPriority);
5540 os::start_thread(this);
5541 }
5542 }
5544 // Where all the work gets done
5545 //
5546 void MemNotifyThread::run() {
5547 assert(this == memnotify_thread(), "expected the singleton MemNotifyThread");
5549 // Set up the select arguments
5550 fd_set rfds;
5551 if (_fd != -1) {
5552 FD_ZERO(&rfds);
5553 FD_SET(_fd, &rfds);
5554 }
5556 // Now wait for the mem_notify device to wake up
5557 while (1) {
5558 // Wait for the mem_notify device to signal us..
5559 int rc = select(_fd+1, _fd != -1 ? &rfds : NULL, NULL, NULL, NULL);
5560 if (rc == -1) {
5561 perror("select!\n");
5562 break;
5563 } else if (rc) {
5564 //ssize_t free_before = os::available_memory();
5565 //tty->print ("Notified: Free: %dK \n",os::available_memory()/1024);
5567 // The kernel is telling us there is not much memory left...
5568 // try to do something about that
5570 // If we are not already in a GC, try one.
5571 if (!Universe::heap()->is_gc_active()) {
5572 Universe::heap()->collect(GCCause::_allocation_failure);
5574 //ssize_t free_after = os::available_memory();
5575 //tty->print ("Post-Notify: Free: %dK\n",free_after/1024);
5576 //tty->print ("GC freed: %dK\n", (free_after - free_before)/1024);
5577 }
5578 // We might want to do something like the following if we find the GC's are not helping...
5579 // Universe::heap()->size_policy()->set_gc_time_limit_exceeded(true);
5580 }
5581 }
5582 }
5584 //
5585 // See if the /dev/mem_notify device exists, and if so, start a thread to monitor it.
5586 //
5587 void MemNotifyThread::start() {
5588 int fd;
5589 fd = open ("/dev/mem_notify", O_RDONLY, 0);
5590 if (fd < 0) {
5591 return;
5592 }
5594 if (memnotify_thread() == NULL) {
5595 new MemNotifyThread(fd);
5596 }
5597 }
5598 #endif // JAVASE_EMBEDDED