Mon, 09 Feb 2009 12:26:05 -0800
6800586: -XX:+PrintGCDateStamps is using mt-unsafe localtime function
Summary: replaced localtime() with localtime_r() on Solaris and Linux.
Reviewed-by: apetrusenko, dholmes, jmasa
1 /*
2 * Copyright 1999-2008 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
25 // do not include precompiled header file
26 # include "incls/_os_linux.cpp.incl"
28 // put OS-includes here
29 # include <sys/types.h>
30 # include <sys/mman.h>
31 # include <pthread.h>
32 # include <signal.h>
33 # include <errno.h>
34 # include <dlfcn.h>
35 # include <stdio.h>
36 # include <unistd.h>
37 # include <sys/resource.h>
38 # include <pthread.h>
39 # include <sys/stat.h>
40 # include <sys/time.h>
41 # include <sys/times.h>
42 # include <sys/utsname.h>
43 # include <sys/socket.h>
44 # include <sys/wait.h>
45 # include <pwd.h>
46 # include <poll.h>
47 # include <semaphore.h>
48 # include <fcntl.h>
49 # include <string.h>
50 # include <syscall.h>
51 # include <sys/sysinfo.h>
52 # include <gnu/libc-version.h>
53 # include <sys/ipc.h>
54 # include <sys/shm.h>
55 # include <link.h>
57 #define MAX_PATH (2 * K)
59 // for timer info max values which include all bits
60 #define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF)
61 #define SEC_IN_NANOSECS 1000000000LL
63 ////////////////////////////////////////////////////////////////////////////////
64 // global variables
65 julong os::Linux::_physical_memory = 0;
67 address os::Linux::_initial_thread_stack_bottom = NULL;
68 uintptr_t os::Linux::_initial_thread_stack_size = 0;
70 int (*os::Linux::_clock_gettime)(clockid_t, struct timespec *) = NULL;
71 int (*os::Linux::_pthread_getcpuclockid)(pthread_t, clockid_t *) = NULL;
72 Mutex* os::Linux::_createThread_lock = NULL;
73 pthread_t os::Linux::_main_thread;
74 int os::Linux::_page_size = -1;
75 bool os::Linux::_is_floating_stack = false;
76 bool os::Linux::_is_NPTL = false;
77 bool os::Linux::_supports_fast_thread_cpu_time = false;
78 const char * os::Linux::_glibc_version = NULL;
79 const char * os::Linux::_libpthread_version = NULL;
81 static jlong initial_time_count=0;
83 static int clock_tics_per_sec = 100;
85 // For diagnostics to print a message once. see run_periodic_checks
86 static sigset_t check_signal_done;
87 static bool check_signals = true;;
89 static pid_t _initial_pid = 0;
91 /* Signal number used to suspend/resume a thread */
93 /* do not use any signal number less than SIGSEGV, see 4355769 */
94 static int SR_signum = SIGUSR2;
95 sigset_t SR_sigset;
97 /* Used to protect dlsym() calls */
98 static pthread_mutex_t dl_mutex;
100 ////////////////////////////////////////////////////////////////////////////////
101 // utility functions
103 static int SR_initialize();
104 static int SR_finalize();
106 julong os::available_memory() {
107 return Linux::available_memory();
108 }
110 julong os::Linux::available_memory() {
111 // values in struct sysinfo are "unsigned long"
112 struct sysinfo si;
113 sysinfo(&si);
115 return (julong)si.freeram * si.mem_unit;
116 }
118 julong os::physical_memory() {
119 return Linux::physical_memory();
120 }
122 julong os::allocatable_physical_memory(julong size) {
123 #ifdef _LP64
124 return size;
125 #else
126 julong result = MIN2(size, (julong)3800*M);
127 if (!is_allocatable(result)) {
128 // See comments under solaris for alignment considerations
129 julong reasonable_size = (julong)2*G - 2 * os::vm_page_size();
130 result = MIN2(size, reasonable_size);
131 }
132 return result;
133 #endif // _LP64
134 }
136 ////////////////////////////////////////////////////////////////////////////////
137 // environment support
139 bool os::getenv(const char* name, char* buf, int len) {
140 const char* val = ::getenv(name);
141 if (val != NULL && strlen(val) < (size_t)len) {
142 strcpy(buf, val);
143 return true;
144 }
145 if (len > 0) buf[0] = 0; // return a null string
146 return false;
147 }
150 // Return true if user is running as root.
152 bool os::have_special_privileges() {
153 static bool init = false;
154 static bool privileges = false;
155 if (!init) {
156 privileges = (getuid() != geteuid()) || (getgid() != getegid());
157 init = true;
158 }
159 return privileges;
160 }
163 #ifndef SYS_gettid
164 // i386: 224, ia64: 1105, amd64: 186, sparc 143
165 #ifdef __ia64__
166 #define SYS_gettid 1105
167 #elif __i386__
168 #define SYS_gettid 224
169 #elif __amd64__
170 #define SYS_gettid 186
171 #elif __sparc__
172 #define SYS_gettid 143
173 #else
174 #error define gettid for the arch
175 #endif
176 #endif
178 // Cpu architecture string
179 #if defined(IA64)
180 static char cpu_arch[] = "ia64";
181 #elif defined(IA32)
182 static char cpu_arch[] = "i386";
183 #elif defined(AMD64)
184 static char cpu_arch[] = "amd64";
185 #elif defined(SPARC)
186 # ifdef _LP64
187 static char cpu_arch[] = "sparcv9";
188 # else
189 static char cpu_arch[] = "sparc";
190 # endif
191 #else
192 #error Add appropriate cpu_arch setting
193 #endif
196 // pid_t gettid()
197 //
198 // Returns the kernel thread id of the currently running thread. Kernel
199 // thread id is used to access /proc.
200 //
201 // (Note that getpid() on LinuxThreads returns kernel thread id too; but
202 // on NPTL, it returns the same pid for all threads, as required by POSIX.)
203 //
204 pid_t os::Linux::gettid() {
205 int rslt = syscall(SYS_gettid);
206 if (rslt == -1) {
207 // old kernel, no NPTL support
208 return getpid();
209 } else {
210 return (pid_t)rslt;
211 }
212 }
214 // Most versions of linux have a bug where the number of processors are
215 // determined by looking at the /proc file system. In a chroot environment,
216 // the system call returns 1. This causes the VM to act as if it is
217 // a single processor and elide locking (see is_MP() call).
218 static bool unsafe_chroot_detected = false;
219 static const char *unstable_chroot_error = "/proc file system not found.\n"
220 "Java may be unstable running multithreaded in a chroot "
221 "environment on Linux when /proc filesystem is not mounted.";
223 void os::Linux::initialize_system_info() {
224 _processor_count = sysconf(_SC_NPROCESSORS_CONF);
225 if (_processor_count == 1) {
226 pid_t pid = os::Linux::gettid();
227 char fname[32];
228 jio_snprintf(fname, sizeof(fname), "/proc/%d", pid);
229 FILE *fp = fopen(fname, "r");
230 if (fp == NULL) {
231 unsafe_chroot_detected = true;
232 } else {
233 fclose(fp);
234 }
235 }
236 _physical_memory = (julong)sysconf(_SC_PHYS_PAGES) * (julong)sysconf(_SC_PAGESIZE);
237 assert(_processor_count > 0, "linux error");
238 }
240 void os::init_system_properties_values() {
241 // char arch[12];
242 // sysinfo(SI_ARCHITECTURE, arch, sizeof(arch));
244 // The next steps are taken in the product version:
245 //
246 // Obtain the JAVA_HOME value from the location of libjvm[_g].so.
247 // This library should be located at:
248 // <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm[_g].so.
249 //
250 // If "/jre/lib/" appears at the right place in the path, then we
251 // assume libjvm[_g].so is installed in a JDK and we use this path.
252 //
253 // Otherwise exit with message: "Could not create the Java virtual machine."
254 //
255 // The following extra steps are taken in the debugging version:
256 //
257 // If "/jre/lib/" does NOT appear at the right place in the path
258 // instead of exit check for $JAVA_HOME environment variable.
259 //
260 // If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>,
261 // then we append a fake suffix "hotspot/libjvm[_g].so" to this path so
262 // it looks like libjvm[_g].so is installed there
263 // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm[_g].so.
264 //
265 // Otherwise exit.
266 //
267 // Important note: if the location of libjvm.so changes this
268 // code needs to be changed accordingly.
270 // The next few definitions allow the code to be verbatim:
271 #define malloc(n) (char*)NEW_C_HEAP_ARRAY(char, (n))
272 #define getenv(n) ::getenv(n)
274 /*
275 * See ld(1):
276 * The linker uses the following search paths to locate required
277 * shared libraries:
278 * 1: ...
279 * ...
280 * 7: The default directories, normally /lib and /usr/lib.
281 */
282 #if defined(AMD64) || defined(_LP64) && (defined(SPARC) || defined(PPC) || defined(S390))
283 #define DEFAULT_LIBPATH "/usr/lib64:/lib64:/lib:/usr/lib"
284 #else
285 #define DEFAULT_LIBPATH "/lib:/usr/lib"
286 #endif
288 #define EXTENSIONS_DIR "/lib/ext"
289 #define ENDORSED_DIR "/lib/endorsed"
290 #define REG_DIR "/usr/java/packages"
292 {
293 /* sysclasspath, java_home, dll_dir */
294 {
295 char *home_path;
296 char *dll_path;
297 char *pslash;
298 char buf[MAXPATHLEN];
299 os::jvm_path(buf, sizeof(buf));
301 // Found the full path to libjvm.so.
302 // Now cut the path to <java_home>/jre if we can.
303 *(strrchr(buf, '/')) = '\0'; /* get rid of /libjvm.so */
304 pslash = strrchr(buf, '/');
305 if (pslash != NULL)
306 *pslash = '\0'; /* get rid of /{client|server|hotspot} */
307 dll_path = malloc(strlen(buf) + 1);
308 if (dll_path == NULL)
309 return;
310 strcpy(dll_path, buf);
311 Arguments::set_dll_dir(dll_path);
313 if (pslash != NULL) {
314 pslash = strrchr(buf, '/');
315 if (pslash != NULL) {
316 *pslash = '\0'; /* get rid of /<arch> */
317 pslash = strrchr(buf, '/');
318 if (pslash != NULL)
319 *pslash = '\0'; /* get rid of /lib */
320 }
321 }
323 home_path = malloc(strlen(buf) + 1);
324 if (home_path == NULL)
325 return;
326 strcpy(home_path, buf);
327 Arguments::set_java_home(home_path);
329 if (!set_boot_path('/', ':'))
330 return;
331 }
333 /*
334 * Where to look for native libraries
335 *
336 * Note: Due to a legacy implementation, most of the library path
337 * is set in the launcher. This was to accomodate linking restrictions
338 * on legacy Linux implementations (which are no longer supported).
339 * Eventually, all the library path setting will be done here.
340 *
341 * However, to prevent the proliferation of improperly built native
342 * libraries, the new path component /usr/java/packages is added here.
343 * Eventually, all the library path setting will be done here.
344 */
345 {
346 char *ld_library_path;
348 /*
349 * Construct the invariant part of ld_library_path. Note that the
350 * space for the colon and the trailing null are provided by the
351 * nulls included by the sizeof operator (so actually we allocate
352 * a byte more than necessary).
353 */
354 ld_library_path = (char *) malloc(sizeof(REG_DIR) + sizeof("/lib/") +
355 strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH));
356 sprintf(ld_library_path, REG_DIR "/lib/%s:" DEFAULT_LIBPATH, cpu_arch);
358 /*
359 * Get the user setting of LD_LIBRARY_PATH, and prepended it. It
360 * should always exist (until the legacy problem cited above is
361 * addressed).
362 */
363 char *v = getenv("LD_LIBRARY_PATH");
364 if (v != NULL) {
365 char *t = ld_library_path;
366 /* That's +1 for the colon and +1 for the trailing '\0' */
367 ld_library_path = (char *) malloc(strlen(v) + 1 + strlen(t) + 1);
368 sprintf(ld_library_path, "%s:%s", v, t);
369 }
370 Arguments::set_library_path(ld_library_path);
371 }
373 /*
374 * Extensions directories.
375 *
376 * Note that the space for the colon and the trailing null are provided
377 * by the nulls included by the sizeof operator (so actually one byte more
378 * than necessary is allocated).
379 */
380 {
381 char *buf = malloc(strlen(Arguments::get_java_home()) +
382 sizeof(EXTENSIONS_DIR) + sizeof(REG_DIR) + sizeof(EXTENSIONS_DIR));
383 sprintf(buf, "%s" EXTENSIONS_DIR ":" REG_DIR EXTENSIONS_DIR,
384 Arguments::get_java_home());
385 Arguments::set_ext_dirs(buf);
386 }
388 /* Endorsed standards default directory. */
389 {
390 char * buf;
391 buf = malloc(strlen(Arguments::get_java_home()) + sizeof(ENDORSED_DIR));
392 sprintf(buf, "%s" ENDORSED_DIR, Arguments::get_java_home());
393 Arguments::set_endorsed_dirs(buf);
394 }
395 }
397 #undef malloc
398 #undef getenv
399 #undef EXTENSIONS_DIR
400 #undef ENDORSED_DIR
402 // Done
403 return;
404 }
406 ////////////////////////////////////////////////////////////////////////////////
407 // breakpoint support
409 void os::breakpoint() {
410 BREAKPOINT;
411 }
413 extern "C" void breakpoint() {
414 // use debugger to set breakpoint here
415 }
417 ////////////////////////////////////////////////////////////////////////////////
418 // signal support
420 debug_only(static bool signal_sets_initialized = false);
421 static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs;
423 bool os::Linux::is_sig_ignored(int sig) {
424 struct sigaction oact;
425 sigaction(sig, (struct sigaction*)NULL, &oact);
426 void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*, oact.sa_sigaction)
427 : CAST_FROM_FN_PTR(void*, oact.sa_handler);
428 if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN))
429 return true;
430 else
431 return false;
432 }
434 void os::Linux::signal_sets_init() {
435 // Should also have an assertion stating we are still single-threaded.
436 assert(!signal_sets_initialized, "Already initialized");
437 // Fill in signals that are necessarily unblocked for all threads in
438 // the VM. Currently, we unblock the following signals:
439 // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden
440 // by -Xrs (=ReduceSignalUsage));
441 // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all
442 // other threads. The "ReduceSignalUsage" boolean tells us not to alter
443 // the dispositions or masks wrt these signals.
444 // Programs embedding the VM that want to use the above signals for their
445 // own purposes must, at this time, use the "-Xrs" option to prevent
446 // interference with shutdown hooks and BREAK_SIGNAL thread dumping.
447 // (See bug 4345157, and other related bugs).
448 // In reality, though, unblocking these signals is really a nop, since
449 // these signals are not blocked by default.
450 sigemptyset(&unblocked_sigs);
451 sigemptyset(&allowdebug_blocked_sigs);
452 sigaddset(&unblocked_sigs, SIGILL);
453 sigaddset(&unblocked_sigs, SIGSEGV);
454 sigaddset(&unblocked_sigs, SIGBUS);
455 sigaddset(&unblocked_sigs, SIGFPE);
456 sigaddset(&unblocked_sigs, SR_signum);
458 if (!ReduceSignalUsage) {
459 if (!os::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) {
460 sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL);
461 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL);
462 }
463 if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) {
464 sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL);
465 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL);
466 }
467 if (!os::Linux::is_sig_ignored(SHUTDOWN3_SIGNAL)) {
468 sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL);
469 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN3_SIGNAL);
470 }
471 }
472 // Fill in signals that are blocked by all but the VM thread.
473 sigemptyset(&vm_sigs);
474 if (!ReduceSignalUsage)
475 sigaddset(&vm_sigs, BREAK_SIGNAL);
476 debug_only(signal_sets_initialized = true);
478 }
480 // These are signals that are unblocked while a thread is running Java.
481 // (For some reason, they get blocked by default.)
482 sigset_t* os::Linux::unblocked_signals() {
483 assert(signal_sets_initialized, "Not initialized");
484 return &unblocked_sigs;
485 }
487 // These are the signals that are blocked while a (non-VM) thread is
488 // running Java. Only the VM thread handles these signals.
489 sigset_t* os::Linux::vm_signals() {
490 assert(signal_sets_initialized, "Not initialized");
491 return &vm_sigs;
492 }
494 // These are signals that are blocked during cond_wait to allow debugger in
495 sigset_t* os::Linux::allowdebug_blocked_signals() {
496 assert(signal_sets_initialized, "Not initialized");
497 return &allowdebug_blocked_sigs;
498 }
500 void os::Linux::hotspot_sigmask(Thread* thread) {
502 //Save caller's signal mask before setting VM signal mask
503 sigset_t caller_sigmask;
504 pthread_sigmask(SIG_BLOCK, NULL, &caller_sigmask);
506 OSThread* osthread = thread->osthread();
507 osthread->set_caller_sigmask(caller_sigmask);
509 pthread_sigmask(SIG_UNBLOCK, os::Linux::unblocked_signals(), NULL);
511 if (!ReduceSignalUsage) {
512 if (thread->is_VM_thread()) {
513 // Only the VM thread handles BREAK_SIGNAL ...
514 pthread_sigmask(SIG_UNBLOCK, vm_signals(), NULL);
515 } else {
516 // ... all other threads block BREAK_SIGNAL
517 pthread_sigmask(SIG_BLOCK, vm_signals(), NULL);
518 }
519 }
520 }
522 //////////////////////////////////////////////////////////////////////////////
523 // detecting pthread library
525 void os::Linux::libpthread_init() {
526 // Save glibc and pthread version strings. Note that _CS_GNU_LIBC_VERSION
527 // and _CS_GNU_LIBPTHREAD_VERSION are supported in glibc >= 2.3.2. Use a
528 // generic name for earlier versions.
529 // Define macros here so we can build HotSpot on old systems.
530 # ifndef _CS_GNU_LIBC_VERSION
531 # define _CS_GNU_LIBC_VERSION 2
532 # endif
533 # ifndef _CS_GNU_LIBPTHREAD_VERSION
534 # define _CS_GNU_LIBPTHREAD_VERSION 3
535 # endif
537 size_t n = confstr(_CS_GNU_LIBC_VERSION, NULL, 0);
538 if (n > 0) {
539 char *str = (char *)malloc(n);
540 confstr(_CS_GNU_LIBC_VERSION, str, n);
541 os::Linux::set_glibc_version(str);
542 } else {
543 // _CS_GNU_LIBC_VERSION is not supported, try gnu_get_libc_version()
544 static char _gnu_libc_version[32];
545 jio_snprintf(_gnu_libc_version, sizeof(_gnu_libc_version),
546 "glibc %s %s", gnu_get_libc_version(), gnu_get_libc_release());
547 os::Linux::set_glibc_version(_gnu_libc_version);
548 }
550 n = confstr(_CS_GNU_LIBPTHREAD_VERSION, NULL, 0);
551 if (n > 0) {
552 char *str = (char *)malloc(n);
553 confstr(_CS_GNU_LIBPTHREAD_VERSION, str, n);
554 // Vanilla RH-9 (glibc 2.3.2) has a bug that confstr() always tells
555 // us "NPTL-0.29" even we are running with LinuxThreads. Check if this
556 // is the case. LinuxThreads has a hard limit on max number of threads.
557 // So sysconf(_SC_THREAD_THREADS_MAX) will return a positive value.
558 // On the other hand, NPTL does not have such a limit, sysconf()
559 // will return -1 and errno is not changed. Check if it is really NPTL.
560 if (strcmp(os::Linux::glibc_version(), "glibc 2.3.2") == 0 &&
561 strstr(str, "NPTL") &&
562 sysconf(_SC_THREAD_THREADS_MAX) > 0) {
563 free(str);
564 os::Linux::set_libpthread_version("linuxthreads");
565 } else {
566 os::Linux::set_libpthread_version(str);
567 }
568 } else {
569 // glibc before 2.3.2 only has LinuxThreads.
570 os::Linux::set_libpthread_version("linuxthreads");
571 }
573 if (strstr(libpthread_version(), "NPTL")) {
574 os::Linux::set_is_NPTL();
575 } else {
576 os::Linux::set_is_LinuxThreads();
577 }
579 // LinuxThreads have two flavors: floating-stack mode, which allows variable
580 // stack size; and fixed-stack mode. NPTL is always floating-stack.
581 if (os::Linux::is_NPTL() || os::Linux::supports_variable_stack_size()) {
582 os::Linux::set_is_floating_stack();
583 }
584 }
586 /////////////////////////////////////////////////////////////////////////////
587 // thread stack
589 // Force Linux kernel to expand current thread stack. If "bottom" is close
590 // to the stack guard, caller should block all signals.
591 //
592 // MAP_GROWSDOWN:
593 // A special mmap() flag that is used to implement thread stacks. It tells
594 // kernel that the memory region should extend downwards when needed. This
595 // allows early versions of LinuxThreads to only mmap the first few pages
596 // when creating a new thread. Linux kernel will automatically expand thread
597 // stack as needed (on page faults).
598 //
599 // However, because the memory region of a MAP_GROWSDOWN stack can grow on
600 // demand, if a page fault happens outside an already mapped MAP_GROWSDOWN
601 // region, it's hard to tell if the fault is due to a legitimate stack
602 // access or because of reading/writing non-exist memory (e.g. buffer
603 // overrun). As a rule, if the fault happens below current stack pointer,
604 // Linux kernel does not expand stack, instead a SIGSEGV is sent to the
605 // application (see Linux kernel fault.c).
606 //
607 // This Linux feature can cause SIGSEGV when VM bangs thread stack for
608 // stack overflow detection.
609 //
610 // Newer version of LinuxThreads (since glibc-2.2, or, RH-7.x) and NPTL do
611 // not use this flag. However, the stack of initial thread is not created
612 // by pthread, it is still MAP_GROWSDOWN. Also it's possible (though
613 // unlikely) that user code can create a thread with MAP_GROWSDOWN stack
614 // and then attach the thread to JVM.
615 //
616 // To get around the problem and allow stack banging on Linux, we need to
617 // manually expand thread stack after receiving the SIGSEGV.
618 //
619 // There are two ways to expand thread stack to address "bottom", we used
620 // both of them in JVM before 1.5:
621 // 1. adjust stack pointer first so that it is below "bottom", and then
622 // touch "bottom"
623 // 2. mmap() the page in question
624 //
625 // Now alternate signal stack is gone, it's harder to use 2. For instance,
626 // if current sp is already near the lower end of page 101, and we need to
627 // call mmap() to map page 100, it is possible that part of the mmap() frame
628 // will be placed in page 100. When page 100 is mapped, it is zero-filled.
629 // That will destroy the mmap() frame and cause VM to crash.
630 //
631 // The following code works by adjusting sp first, then accessing the "bottom"
632 // page to force a page fault. Linux kernel will then automatically expand the
633 // stack mapping.
634 //
635 // _expand_stack_to() assumes its frame size is less than page size, which
636 // should always be true if the function is not inlined.
638 #if __GNUC__ < 3 // gcc 2.x does not support noinline attribute
639 #define NOINLINE
640 #else
641 #define NOINLINE __attribute__ ((noinline))
642 #endif
644 static void _expand_stack_to(address bottom) NOINLINE;
646 static void _expand_stack_to(address bottom) {
647 address sp;
648 size_t size;
649 volatile char *p;
651 // Adjust bottom to point to the largest address within the same page, it
652 // gives us a one-page buffer if alloca() allocates slightly more memory.
653 bottom = (address)align_size_down((uintptr_t)bottom, os::Linux::page_size());
654 bottom += os::Linux::page_size() - 1;
656 // sp might be slightly above current stack pointer; if that's the case, we
657 // will alloca() a little more space than necessary, which is OK. Don't use
658 // os::current_stack_pointer(), as its result can be slightly below current
659 // stack pointer, causing us to not alloca enough to reach "bottom".
660 sp = (address)&sp;
662 if (sp > bottom) {
663 size = sp - bottom;
664 p = (volatile char *)alloca(size);
665 assert(p != NULL && p <= (volatile char *)bottom, "alloca problem?");
666 p[0] = '\0';
667 }
668 }
670 bool os::Linux::manually_expand_stack(JavaThread * t, address addr) {
671 assert(t!=NULL, "just checking");
672 assert(t->osthread()->expanding_stack(), "expand should be set");
673 assert(t->stack_base() != NULL, "stack_base was not initialized");
675 if (addr < t->stack_base() && addr >= t->stack_yellow_zone_base()) {
676 sigset_t mask_all, old_sigset;
677 sigfillset(&mask_all);
678 pthread_sigmask(SIG_SETMASK, &mask_all, &old_sigset);
679 _expand_stack_to(addr);
680 pthread_sigmask(SIG_SETMASK, &old_sigset, NULL);
681 return true;
682 }
683 return false;
684 }
686 //////////////////////////////////////////////////////////////////////////////
687 // create new thread
689 static address highest_vm_reserved_address();
691 // check if it's safe to start a new thread
692 static bool _thread_safety_check(Thread* thread) {
693 if (os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack()) {
694 // Fixed stack LinuxThreads (SuSE Linux/x86, and some versions of Redhat)
695 // Heap is mmap'ed at lower end of memory space. Thread stacks are
696 // allocated (MAP_FIXED) from high address space. Every thread stack
697 // occupies a fixed size slot (usually 2Mbytes, but user can change
698 // it to other values if they rebuild LinuxThreads).
699 //
700 // Problem with MAP_FIXED is that mmap() can still succeed even part of
701 // the memory region has already been mmap'ed. That means if we have too
702 // many threads and/or very large heap, eventually thread stack will
703 // collide with heap.
704 //
705 // Here we try to prevent heap/stack collision by comparing current
706 // stack bottom with the highest address that has been mmap'ed by JVM
707 // plus a safety margin for memory maps created by native code.
708 //
709 // This feature can be disabled by setting ThreadSafetyMargin to 0
710 //
711 if (ThreadSafetyMargin > 0) {
712 address stack_bottom = os::current_stack_base() - os::current_stack_size();
714 // not safe if our stack extends below the safety margin
715 return stack_bottom - ThreadSafetyMargin >= highest_vm_reserved_address();
716 } else {
717 return true;
718 }
719 } else {
720 // Floating stack LinuxThreads or NPTL:
721 // Unlike fixed stack LinuxThreads, thread stacks are not MAP_FIXED. When
722 // there's not enough space left, pthread_create() will fail. If we come
723 // here, that means enough space has been reserved for stack.
724 return true;
725 }
726 }
728 // Thread start routine for all newly created threads
729 static void *java_start(Thread *thread) {
730 // Try to randomize the cache line index of hot stack frames.
731 // This helps when threads of the same stack traces evict each other's
732 // cache lines. The threads can be either from the same JVM instance, or
733 // from different JVM instances. The benefit is especially true for
734 // processors with hyperthreading technology.
735 static int counter = 0;
736 int pid = os::current_process_id();
737 alloca(((pid ^ counter++) & 7) * 128);
739 ThreadLocalStorage::set_thread(thread);
741 OSThread* osthread = thread->osthread();
742 Monitor* sync = osthread->startThread_lock();
744 // non floating stack LinuxThreads needs extra check, see above
745 if (!_thread_safety_check(thread)) {
746 // notify parent thread
747 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
748 osthread->set_state(ZOMBIE);
749 sync->notify_all();
750 return NULL;
751 }
753 // thread_id is kernel thread id (similar to Solaris LWP id)
754 osthread->set_thread_id(os::Linux::gettid());
756 if (UseNUMA) {
757 int lgrp_id = os::numa_get_group_id();
758 if (lgrp_id != -1) {
759 thread->set_lgrp_id(lgrp_id);
760 }
761 }
762 // initialize signal mask for this thread
763 os::Linux::hotspot_sigmask(thread);
765 // initialize floating point control register
766 os::Linux::init_thread_fpu_state();
768 // handshaking with parent thread
769 {
770 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
772 // notify parent thread
773 osthread->set_state(INITIALIZED);
774 sync->notify_all();
776 // wait until os::start_thread()
777 while (osthread->get_state() == INITIALIZED) {
778 sync->wait(Mutex::_no_safepoint_check_flag);
779 }
780 }
782 // call one more level start routine
783 thread->run();
785 return 0;
786 }
788 bool os::create_thread(Thread* thread, ThreadType thr_type, size_t stack_size) {
789 assert(thread->osthread() == NULL, "caller responsible");
791 // Allocate the OSThread object
792 OSThread* osthread = new OSThread(NULL, NULL);
793 if (osthread == NULL) {
794 return false;
795 }
797 // set the correct thread state
798 osthread->set_thread_type(thr_type);
800 // Initial state is ALLOCATED but not INITIALIZED
801 osthread->set_state(ALLOCATED);
803 thread->set_osthread(osthread);
805 // init thread attributes
806 pthread_attr_t attr;
807 pthread_attr_init(&attr);
808 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
810 // stack size
811 if (os::Linux::supports_variable_stack_size()) {
812 // calculate stack size if it's not specified by caller
813 if (stack_size == 0) {
814 stack_size = os::Linux::default_stack_size(thr_type);
816 switch (thr_type) {
817 case os::java_thread:
818 // Java threads use ThreadStackSize which default value can be changed with the flag -Xss
819 if (JavaThread::stack_size_at_create() > 0) stack_size = JavaThread::stack_size_at_create();
820 break;
821 case os::compiler_thread:
822 if (CompilerThreadStackSize > 0) {
823 stack_size = (size_t)(CompilerThreadStackSize * K);
824 break;
825 } // else fall through:
826 // use VMThreadStackSize if CompilerThreadStackSize is not defined
827 case os::vm_thread:
828 case os::pgc_thread:
829 case os::cgc_thread:
830 case os::watcher_thread:
831 if (VMThreadStackSize > 0) stack_size = (size_t)(VMThreadStackSize * K);
832 break;
833 }
834 }
836 stack_size = MAX2(stack_size, os::Linux::min_stack_allowed);
837 pthread_attr_setstacksize(&attr, stack_size);
838 } else {
839 // let pthread_create() pick the default value.
840 }
842 // glibc guard page
843 pthread_attr_setguardsize(&attr, os::Linux::default_guard_size(thr_type));
845 ThreadState state;
847 {
848 // Serialize thread creation if we are running with fixed stack LinuxThreads
849 bool lock = os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack();
850 if (lock) {
851 os::Linux::createThread_lock()->lock_without_safepoint_check();
852 }
854 pthread_t tid;
855 int ret = pthread_create(&tid, &attr, (void* (*)(void*)) java_start, thread);
857 pthread_attr_destroy(&attr);
859 if (ret != 0) {
860 if (PrintMiscellaneous && (Verbose || WizardMode)) {
861 perror("pthread_create()");
862 }
863 // Need to clean up stuff we've allocated so far
864 thread->set_osthread(NULL);
865 delete osthread;
866 if (lock) os::Linux::createThread_lock()->unlock();
867 return false;
868 }
870 // Store pthread info into the OSThread
871 osthread->set_pthread_id(tid);
873 // Wait until child thread is either initialized or aborted
874 {
875 Monitor* sync_with_child = osthread->startThread_lock();
876 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
877 while ((state = osthread->get_state()) == ALLOCATED) {
878 sync_with_child->wait(Mutex::_no_safepoint_check_flag);
879 }
880 }
882 if (lock) {
883 os::Linux::createThread_lock()->unlock();
884 }
885 }
887 // Aborted due to thread limit being reached
888 if (state == ZOMBIE) {
889 thread->set_osthread(NULL);
890 delete osthread;
891 return false;
892 }
894 // The thread is returned suspended (in state INITIALIZED),
895 // and is started higher up in the call chain
896 assert(state == INITIALIZED, "race condition");
897 return true;
898 }
900 /////////////////////////////////////////////////////////////////////////////
901 // attach existing thread
903 // bootstrap the main thread
904 bool os::create_main_thread(JavaThread* thread) {
905 assert(os::Linux::_main_thread == pthread_self(), "should be called inside main thread");
906 return create_attached_thread(thread);
907 }
909 bool os::create_attached_thread(JavaThread* thread) {
910 #ifdef ASSERT
911 thread->verify_not_published();
912 #endif
914 // Allocate the OSThread object
915 OSThread* osthread = new OSThread(NULL, NULL);
917 if (osthread == NULL) {
918 return false;
919 }
921 // Store pthread info into the OSThread
922 osthread->set_thread_id(os::Linux::gettid());
923 osthread->set_pthread_id(::pthread_self());
925 // initialize floating point control register
926 os::Linux::init_thread_fpu_state();
928 // Initial thread state is RUNNABLE
929 osthread->set_state(RUNNABLE);
931 thread->set_osthread(osthread);
933 if (UseNUMA) {
934 int lgrp_id = os::numa_get_group_id();
935 if (lgrp_id != -1) {
936 thread->set_lgrp_id(lgrp_id);
937 }
938 }
940 if (os::Linux::is_initial_thread()) {
941 // If current thread is initial thread, its stack is mapped on demand,
942 // see notes about MAP_GROWSDOWN. Here we try to force kernel to map
943 // the entire stack region to avoid SEGV in stack banging.
944 // It is also useful to get around the heap-stack-gap problem on SuSE
945 // kernel (see 4821821 for details). We first expand stack to the top
946 // of yellow zone, then enable stack yellow zone (order is significant,
947 // enabling yellow zone first will crash JVM on SuSE Linux), so there
948 // is no gap between the last two virtual memory regions.
950 JavaThread *jt = (JavaThread *)thread;
951 address addr = jt->stack_yellow_zone_base();
952 assert(addr != NULL, "initialization problem?");
953 assert(jt->stack_available(addr) > 0, "stack guard should not be enabled");
955 osthread->set_expanding_stack();
956 os::Linux::manually_expand_stack(jt, addr);
957 osthread->clear_expanding_stack();
958 }
960 // initialize signal mask for this thread
961 // and save the caller's signal mask
962 os::Linux::hotspot_sigmask(thread);
964 return true;
965 }
967 void os::pd_start_thread(Thread* thread) {
968 OSThread * osthread = thread->osthread();
969 assert(osthread->get_state() != INITIALIZED, "just checking");
970 Monitor* sync_with_child = osthread->startThread_lock();
971 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
972 sync_with_child->notify();
973 }
975 // Free Linux resources related to the OSThread
976 void os::free_thread(OSThread* osthread) {
977 assert(osthread != NULL, "osthread not set");
979 if (Thread::current()->osthread() == osthread) {
980 // Restore caller's signal mask
981 sigset_t sigmask = osthread->caller_sigmask();
982 pthread_sigmask(SIG_SETMASK, &sigmask, NULL);
983 }
985 delete osthread;
986 }
988 //////////////////////////////////////////////////////////////////////////////
989 // thread local storage
991 int os::allocate_thread_local_storage() {
992 pthread_key_t key;
993 int rslt = pthread_key_create(&key, NULL);
994 assert(rslt == 0, "cannot allocate thread local storage");
995 return (int)key;
996 }
998 // Note: This is currently not used by VM, as we don't destroy TLS key
999 // on VM exit.
1000 void os::free_thread_local_storage(int index) {
1001 int rslt = pthread_key_delete((pthread_key_t)index);
1002 assert(rslt == 0, "invalid index");
1003 }
1005 void os::thread_local_storage_at_put(int index, void* value) {
1006 int rslt = pthread_setspecific((pthread_key_t)index, value);
1007 assert(rslt == 0, "pthread_setspecific failed");
1008 }
1010 extern "C" Thread* get_thread() {
1011 return ThreadLocalStorage::thread();
1012 }
1014 //////////////////////////////////////////////////////////////////////////////
1015 // initial thread
1017 // Check if current thread is the initial thread, similar to Solaris thr_main.
1018 bool os::Linux::is_initial_thread(void) {
1019 char dummy;
1020 // If called before init complete, thread stack bottom will be null.
1021 // Can be called if fatal error occurs before initialization.
1022 if (initial_thread_stack_bottom() == NULL) return false;
1023 assert(initial_thread_stack_bottom() != NULL &&
1024 initial_thread_stack_size() != 0,
1025 "os::init did not locate initial thread's stack region");
1026 if ((address)&dummy >= initial_thread_stack_bottom() &&
1027 (address)&dummy < initial_thread_stack_bottom() + initial_thread_stack_size())
1028 return true;
1029 else return false;
1030 }
1032 // Find the virtual memory area that contains addr
1033 static bool find_vma(address addr, address* vma_low, address* vma_high) {
1034 FILE *fp = fopen("/proc/self/maps", "r");
1035 if (fp) {
1036 address low, high;
1037 while (!feof(fp)) {
1038 if (fscanf(fp, "%p-%p", &low, &high) == 2) {
1039 if (low <= addr && addr < high) {
1040 if (vma_low) *vma_low = low;
1041 if (vma_high) *vma_high = high;
1042 fclose (fp);
1043 return true;
1044 }
1045 }
1046 for (;;) {
1047 int ch = fgetc(fp);
1048 if (ch == EOF || ch == (int)'\n') break;
1049 }
1050 }
1051 fclose(fp);
1052 }
1053 return false;
1054 }
1056 // Locate initial thread stack. This special handling of initial thread stack
1057 // is needed because pthread_getattr_np() on most (all?) Linux distros returns
1058 // bogus value for initial thread.
1059 void os::Linux::capture_initial_stack(size_t max_size) {
1060 // stack size is the easy part, get it from RLIMIT_STACK
1061 size_t stack_size;
1062 struct rlimit rlim;
1063 getrlimit(RLIMIT_STACK, &rlim);
1064 stack_size = rlim.rlim_cur;
1066 // 6308388: a bug in ld.so will relocate its own .data section to the
1067 // lower end of primordial stack; reduce ulimit -s value a little bit
1068 // so we won't install guard page on ld.so's data section.
1069 stack_size -= 2 * page_size();
1071 // 4441425: avoid crash with "unlimited" stack size on SuSE 7.1 or Redhat
1072 // 7.1, in both cases we will get 2G in return value.
1073 // 4466587: glibc 2.2.x compiled w/o "--enable-kernel=2.4.0" (RH 7.0,
1074 // SuSE 7.2, Debian) can not handle alternate signal stack correctly
1075 // for initial thread if its stack size exceeds 6M. Cap it at 2M,
1076 // in case other parts in glibc still assumes 2M max stack size.
1077 // FIXME: alt signal stack is gone, maybe we can relax this constraint?
1078 #ifndef IA64
1079 if (stack_size > 2 * K * K) stack_size = 2 * K * K;
1080 #else
1081 // Problem still exists RH7.2 (IA64 anyway) but 2MB is a little small
1082 if (stack_size > 4 * K * K) stack_size = 4 * K * K;
1083 #endif
1085 // Try to figure out where the stack base (top) is. This is harder.
1086 //
1087 // When an application is started, glibc saves the initial stack pointer in
1088 // a global variable "__libc_stack_end", which is then used by system
1089 // libraries. __libc_stack_end should be pretty close to stack top. The
1090 // variable is available since the very early days. However, because it is
1091 // a private interface, it could disappear in the future.
1092 //
1093 // Linux kernel saves start_stack information in /proc/<pid>/stat. Similar
1094 // to __libc_stack_end, it is very close to stack top, but isn't the real
1095 // stack top. Note that /proc may not exist if VM is running as a chroot
1096 // program, so reading /proc/<pid>/stat could fail. Also the contents of
1097 // /proc/<pid>/stat could change in the future (though unlikely).
1098 //
1099 // We try __libc_stack_end first. If that doesn't work, look for
1100 // /proc/<pid>/stat. If neither of them works, we use current stack pointer
1101 // as a hint, which should work well in most cases.
1103 uintptr_t stack_start;
1105 // try __libc_stack_end first
1106 uintptr_t *p = (uintptr_t *)dlsym(RTLD_DEFAULT, "__libc_stack_end");
1107 if (p && *p) {
1108 stack_start = *p;
1109 } else {
1110 // see if we can get the start_stack field from /proc/self/stat
1111 FILE *fp;
1112 int pid;
1113 char state;
1114 int ppid;
1115 int pgrp;
1116 int session;
1117 int nr;
1118 int tpgrp;
1119 unsigned long flags;
1120 unsigned long minflt;
1121 unsigned long cminflt;
1122 unsigned long majflt;
1123 unsigned long cmajflt;
1124 unsigned long utime;
1125 unsigned long stime;
1126 long cutime;
1127 long cstime;
1128 long prio;
1129 long nice;
1130 long junk;
1131 long it_real;
1132 uintptr_t start;
1133 uintptr_t vsize;
1134 uintptr_t rss;
1135 unsigned long rsslim;
1136 uintptr_t scodes;
1137 uintptr_t ecode;
1138 int i;
1140 // Figure what the primordial thread stack base is. Code is inspired
1141 // by email from Hans Boehm. /proc/self/stat begins with current pid,
1142 // followed by command name surrounded by parentheses, state, etc.
1143 char stat[2048];
1144 int statlen;
1146 fp = fopen("/proc/self/stat", "r");
1147 if (fp) {
1148 statlen = fread(stat, 1, 2047, fp);
1149 stat[statlen] = '\0';
1150 fclose(fp);
1152 // Skip pid and the command string. Note that we could be dealing with
1153 // weird command names, e.g. user could decide to rename java launcher
1154 // to "java 1.4.2 :)", then the stat file would look like
1155 // 1234 (java 1.4.2 :)) R ... ...
1156 // We don't really need to know the command string, just find the last
1157 // occurrence of ")" and then start parsing from there. See bug 4726580.
1158 char * s = strrchr(stat, ')');
1160 i = 0;
1161 if (s) {
1162 // Skip blank chars
1163 do s++; while (isspace(*s));
1165 /* 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 */
1166 /* 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 */
1167 i = sscanf(s, "%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu %ld %ld %ld %ld %ld %ld "
1168 UINTX_FORMAT UINTX_FORMAT UINTX_FORMAT
1169 " %lu "
1170 UINTX_FORMAT UINTX_FORMAT UINTX_FORMAT,
1171 &state, /* 3 %c */
1172 &ppid, /* 4 %d */
1173 &pgrp, /* 5 %d */
1174 &session, /* 6 %d */
1175 &nr, /* 7 %d */
1176 &tpgrp, /* 8 %d */
1177 &flags, /* 9 %lu */
1178 &minflt, /* 10 %lu */
1179 &cminflt, /* 11 %lu */
1180 &majflt, /* 12 %lu */
1181 &cmajflt, /* 13 %lu */
1182 &utime, /* 14 %lu */
1183 &stime, /* 15 %lu */
1184 &cutime, /* 16 %ld */
1185 &cstime, /* 17 %ld */
1186 &prio, /* 18 %ld */
1187 &nice, /* 19 %ld */
1188 &junk, /* 20 %ld */
1189 &it_real, /* 21 %ld */
1190 &start, /* 22 UINTX_FORMAT */
1191 &vsize, /* 23 UINTX_FORMAT */
1192 &rss, /* 24 UINTX_FORMAT */
1193 &rsslim, /* 25 %lu */
1194 &scodes, /* 26 UINTX_FORMAT */
1195 &ecode, /* 27 UINTX_FORMAT */
1196 &stack_start); /* 28 UINTX_FORMAT */
1197 }
1199 if (i != 28 - 2) {
1200 assert(false, "Bad conversion from /proc/self/stat");
1201 // product mode - assume we are the initial thread, good luck in the
1202 // embedded case.
1203 warning("Can't detect initial thread stack location - bad conversion");
1204 stack_start = (uintptr_t) &rlim;
1205 }
1206 } else {
1207 // For some reason we can't open /proc/self/stat (for example, running on
1208 // FreeBSD with a Linux emulator, or inside chroot), this should work for
1209 // most cases, so don't abort:
1210 warning("Can't detect initial thread stack location - no /proc/self/stat");
1211 stack_start = (uintptr_t) &rlim;
1212 }
1213 }
1215 // Now we have a pointer (stack_start) very close to the stack top, the
1216 // next thing to do is to figure out the exact location of stack top. We
1217 // can find out the virtual memory area that contains stack_start by
1218 // reading /proc/self/maps, it should be the last vma in /proc/self/maps,
1219 // and its upper limit is the real stack top. (again, this would fail if
1220 // running inside chroot, because /proc may not exist.)
1222 uintptr_t stack_top;
1223 address low, high;
1224 if (find_vma((address)stack_start, &low, &high)) {
1225 // success, "high" is the true stack top. (ignore "low", because initial
1226 // thread stack grows on demand, its real bottom is high - RLIMIT_STACK.)
1227 stack_top = (uintptr_t)high;
1228 } else {
1229 // failed, likely because /proc/self/maps does not exist
1230 warning("Can't detect initial thread stack location - find_vma failed");
1231 // best effort: stack_start is normally within a few pages below the real
1232 // stack top, use it as stack top, and reduce stack size so we won't put
1233 // guard page outside stack.
1234 stack_top = stack_start;
1235 stack_size -= 16 * page_size();
1236 }
1238 // stack_top could be partially down the page so align it
1239 stack_top = align_size_up(stack_top, page_size());
1241 if (max_size && stack_size > max_size) {
1242 _initial_thread_stack_size = max_size;
1243 } else {
1244 _initial_thread_stack_size = stack_size;
1245 }
1247 _initial_thread_stack_size = align_size_down(_initial_thread_stack_size, page_size());
1248 _initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size;
1249 }
1251 ////////////////////////////////////////////////////////////////////////////////
1252 // time support
1254 // Time since start-up in seconds to a fine granularity.
1255 // Used by VMSelfDestructTimer and the MemProfiler.
1256 double os::elapsedTime() {
1258 return (double)(os::elapsed_counter()) * 0.000001;
1259 }
1261 jlong os::elapsed_counter() {
1262 timeval time;
1263 int status = gettimeofday(&time, NULL);
1264 return jlong(time.tv_sec) * 1000 * 1000 + jlong(time.tv_usec) - initial_time_count;
1265 }
1267 jlong os::elapsed_frequency() {
1268 return (1000 * 1000);
1269 }
1271 // For now, we say that linux does not support vtime. I have no idea
1272 // whether it can actually be made to (DLD, 9/13/05).
1274 bool os::supports_vtime() { return false; }
1275 bool os::enable_vtime() { return false; }
1276 bool os::vtime_enabled() { return false; }
1277 double os::elapsedVTime() {
1278 // better than nothing, but not much
1279 return elapsedTime();
1280 }
1282 jlong os::javaTimeMillis() {
1283 timeval time;
1284 int status = gettimeofday(&time, NULL);
1285 assert(status != -1, "linux error");
1286 return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000);
1287 }
1289 #ifndef CLOCK_MONOTONIC
1290 #define CLOCK_MONOTONIC (1)
1291 #endif
1293 void os::Linux::clock_init() {
1294 // we do dlopen's in this particular order due to bug in linux
1295 // dynamical loader (see 6348968) leading to crash on exit
1296 void* handle = dlopen("librt.so.1", RTLD_LAZY);
1297 if (handle == NULL) {
1298 handle = dlopen("librt.so", RTLD_LAZY);
1299 }
1301 if (handle) {
1302 int (*clock_getres_func)(clockid_t, struct timespec*) =
1303 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres");
1304 int (*clock_gettime_func)(clockid_t, struct timespec*) =
1305 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime");
1306 if (clock_getres_func && clock_gettime_func) {
1307 // See if monotonic clock is supported by the kernel. Note that some
1308 // early implementations simply return kernel jiffies (updated every
1309 // 1/100 or 1/1000 second). It would be bad to use such a low res clock
1310 // for nano time (though the monotonic property is still nice to have).
1311 // It's fixed in newer kernels, however clock_getres() still returns
1312 // 1/HZ. We check if clock_getres() works, but will ignore its reported
1313 // resolution for now. Hopefully as people move to new kernels, this
1314 // won't be a problem.
1315 struct timespec res;
1316 struct timespec tp;
1317 if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 &&
1318 clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) {
1319 // yes, monotonic clock is supported
1320 _clock_gettime = clock_gettime_func;
1321 } else {
1322 // close librt if there is no monotonic clock
1323 dlclose(handle);
1324 }
1325 }
1326 }
1327 }
1329 #ifndef SYS_clock_getres
1331 #if defined(IA32) || defined(AMD64)
1332 #define SYS_clock_getres IA32_ONLY(266) AMD64_ONLY(229)
1333 #else
1334 #error Value of SYS_clock_getres not known on this platform
1335 #endif
1337 #endif
1339 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y)
1341 void os::Linux::fast_thread_clock_init() {
1342 if (!UseLinuxPosixThreadCPUClocks) {
1343 return;
1344 }
1345 clockid_t clockid;
1346 struct timespec tp;
1347 int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) =
1348 (int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid");
1350 // Switch to using fast clocks for thread cpu time if
1351 // the sys_clock_getres() returns 0 error code.
1352 // Note, that some kernels may support the current thread
1353 // clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks
1354 // returned by the pthread_getcpuclockid().
1355 // If the fast Posix clocks are supported then the sys_clock_getres()
1356 // must return at least tp.tv_sec == 0 which means a resolution
1357 // better than 1 sec. This is extra check for reliability.
1359 if(pthread_getcpuclockid_func &&
1360 pthread_getcpuclockid_func(_main_thread, &clockid) == 0 &&
1361 sys_clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) {
1363 _supports_fast_thread_cpu_time = true;
1364 _pthread_getcpuclockid = pthread_getcpuclockid_func;
1365 }
1366 }
1368 jlong os::javaTimeNanos() {
1369 if (Linux::supports_monotonic_clock()) {
1370 struct timespec tp;
1371 int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp);
1372 assert(status == 0, "gettime error");
1373 jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec);
1374 return result;
1375 } else {
1376 timeval time;
1377 int status = gettimeofday(&time, NULL);
1378 assert(status != -1, "linux error");
1379 jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec);
1380 return 1000 * usecs;
1381 }
1382 }
1384 void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) {
1385 if (Linux::supports_monotonic_clock()) {
1386 info_ptr->max_value = ALL_64_BITS;
1388 // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past
1389 info_ptr->may_skip_backward = false; // not subject to resetting or drifting
1390 info_ptr->may_skip_forward = false; // not subject to resetting or drifting
1391 } else {
1392 // gettimeofday - based on time in seconds since the Epoch thus does not wrap
1393 info_ptr->max_value = ALL_64_BITS;
1395 // gettimeofday is a real time clock so it skips
1396 info_ptr->may_skip_backward = true;
1397 info_ptr->may_skip_forward = true;
1398 }
1400 info_ptr->kind = JVMTI_TIMER_ELAPSED; // elapsed not CPU time
1401 }
1403 // Return the real, user, and system times in seconds from an
1404 // arbitrary fixed point in the past.
1405 bool os::getTimesSecs(double* process_real_time,
1406 double* process_user_time,
1407 double* process_system_time) {
1408 struct tms ticks;
1409 clock_t real_ticks = times(&ticks);
1411 if (real_ticks == (clock_t) (-1)) {
1412 return false;
1413 } else {
1414 double ticks_per_second = (double) clock_tics_per_sec;
1415 *process_user_time = ((double) ticks.tms_utime) / ticks_per_second;
1416 *process_system_time = ((double) ticks.tms_stime) / ticks_per_second;
1417 *process_real_time = ((double) real_ticks) / ticks_per_second;
1419 return true;
1420 }
1421 }
1424 char * os::local_time_string(char *buf, size_t buflen) {
1425 struct tm t;
1426 time_t long_time;
1427 time(&long_time);
1428 localtime_r(&long_time, &t);
1429 jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d",
1430 t.tm_year + 1900, t.tm_mon + 1, t.tm_mday,
1431 t.tm_hour, t.tm_min, t.tm_sec);
1432 return buf;
1433 }
1435 struct tm* os::localtime_pd(const time_t* clock, struct tm* res) {
1436 return localtime_r(clock, res);
1437 }
1439 ////////////////////////////////////////////////////////////////////////////////
1440 // runtime exit support
1442 // Note: os::shutdown() might be called very early during initialization, or
1443 // called from signal handler. Before adding something to os::shutdown(), make
1444 // sure it is async-safe and can handle partially initialized VM.
1445 void os::shutdown() {
1447 // allow PerfMemory to attempt cleanup of any persistent resources
1448 perfMemory_exit();
1450 // needs to remove object in file system
1451 AttachListener::abort();
1453 // flush buffered output, finish log files
1454 ostream_abort();
1456 // Check for abort hook
1457 abort_hook_t abort_hook = Arguments::abort_hook();
1458 if (abort_hook != NULL) {
1459 abort_hook();
1460 }
1462 }
1464 // Note: os::abort() might be called very early during initialization, or
1465 // called from signal handler. Before adding something to os::abort(), make
1466 // sure it is async-safe and can handle partially initialized VM.
1467 void os::abort(bool dump_core) {
1468 os::shutdown();
1469 if (dump_core) {
1470 #ifndef PRODUCT
1471 fdStream out(defaultStream::output_fd());
1472 out.print_raw("Current thread is ");
1473 char buf[16];
1474 jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id());
1475 out.print_raw_cr(buf);
1476 out.print_raw_cr("Dumping core ...");
1477 #endif
1478 ::abort(); // dump core
1479 }
1481 ::exit(1);
1482 }
1484 // Die immediately, no exit hook, no abort hook, no cleanup.
1485 void os::die() {
1486 // _exit() on LinuxThreads only kills current thread
1487 ::abort();
1488 }
1490 // unused on linux for now.
1491 void os::set_error_file(const char *logfile) {}
1493 intx os::current_thread_id() { return (intx)pthread_self(); }
1494 int os::current_process_id() {
1496 // Under the old linux thread library, linux gives each thread
1497 // its own process id. Because of this each thread will return
1498 // a different pid if this method were to return the result
1499 // of getpid(2). Linux provides no api that returns the pid
1500 // of the launcher thread for the vm. This implementation
1501 // returns a unique pid, the pid of the launcher thread
1502 // that starts the vm 'process'.
1504 // Under the NPTL, getpid() returns the same pid as the
1505 // launcher thread rather than a unique pid per thread.
1506 // Use gettid() if you want the old pre NPTL behaviour.
1508 // if you are looking for the result of a call to getpid() that
1509 // returns a unique pid for the calling thread, then look at the
1510 // OSThread::thread_id() method in osThread_linux.hpp file
1512 return (int)(_initial_pid ? _initial_pid : getpid());
1513 }
1515 // DLL functions
1517 const char* os::dll_file_extension() { return ".so"; }
1519 const char* os::get_temp_directory() { return "/tmp/"; }
1521 void os::dll_build_name(
1522 char* buffer, size_t buflen, const char* pname, const char* fname) {
1523 // copied from libhpi
1524 const size_t pnamelen = pname ? strlen(pname) : 0;
1526 /* Quietly truncate on buffer overflow. Should be an error. */
1527 if (pnamelen + strlen(fname) + 10 > (size_t) buflen) {
1528 *buffer = '\0';
1529 return;
1530 }
1532 if (pnamelen == 0) {
1533 sprintf(buffer, "lib%s.so", fname);
1534 } else {
1535 sprintf(buffer, "%s/lib%s.so", pname, fname);
1536 }
1537 }
1539 const char* os::get_current_directory(char *buf, int buflen) {
1540 return getcwd(buf, buflen);
1541 }
1543 // check if addr is inside libjvm[_g].so
1544 bool os::address_is_in_vm(address addr) {
1545 static address libjvm_base_addr;
1546 Dl_info dlinfo;
1548 if (libjvm_base_addr == NULL) {
1549 dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo);
1550 libjvm_base_addr = (address)dlinfo.dli_fbase;
1551 assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm");
1552 }
1554 if (dladdr((void *)addr, &dlinfo)) {
1555 if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true;
1556 }
1558 return false;
1559 }
1561 bool os::dll_address_to_function_name(address addr, char *buf,
1562 int buflen, int *offset) {
1563 Dl_info dlinfo;
1565 if (dladdr((void*)addr, &dlinfo) && dlinfo.dli_sname != NULL) {
1566 if (buf) jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname);
1567 if (offset) *offset = addr - (address)dlinfo.dli_saddr;
1568 return true;
1569 } else {
1570 if (buf) buf[0] = '\0';
1571 if (offset) *offset = -1;
1572 return false;
1573 }
1574 }
1576 struct _address_to_library_name {
1577 address addr; // input : memory address
1578 size_t buflen; // size of fname
1579 char* fname; // output: library name
1580 address base; // library base addr
1581 };
1583 static int address_to_library_name_callback(struct dl_phdr_info *info,
1584 size_t size, void *data) {
1585 int i;
1586 bool found = false;
1587 address libbase = NULL;
1588 struct _address_to_library_name * d = (struct _address_to_library_name *)data;
1590 // iterate through all loadable segments
1591 for (i = 0; i < info->dlpi_phnum; i++) {
1592 address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr);
1593 if (info->dlpi_phdr[i].p_type == PT_LOAD) {
1594 // base address of a library is the lowest address of its loaded
1595 // segments.
1596 if (libbase == NULL || libbase > segbase) {
1597 libbase = segbase;
1598 }
1599 // see if 'addr' is within current segment
1600 if (segbase <= d->addr &&
1601 d->addr < segbase + info->dlpi_phdr[i].p_memsz) {
1602 found = true;
1603 }
1604 }
1605 }
1607 // dlpi_name is NULL or empty if the ELF file is executable, return 0
1608 // so dll_address_to_library_name() can fall through to use dladdr() which
1609 // can figure out executable name from argv[0].
1610 if (found && info->dlpi_name && info->dlpi_name[0]) {
1611 d->base = libbase;
1612 if (d->fname) {
1613 jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name);
1614 }
1615 return 1;
1616 }
1617 return 0;
1618 }
1620 bool os::dll_address_to_library_name(address addr, char* buf,
1621 int buflen, int* offset) {
1622 Dl_info dlinfo;
1623 struct _address_to_library_name data;
1625 // There is a bug in old glibc dladdr() implementation that it could resolve
1626 // to wrong library name if the .so file has a base address != NULL. Here
1627 // we iterate through the program headers of all loaded libraries to find
1628 // out which library 'addr' really belongs to. This workaround can be
1629 // removed once the minimum requirement for glibc is moved to 2.3.x.
1630 data.addr = addr;
1631 data.fname = buf;
1632 data.buflen = buflen;
1633 data.base = NULL;
1634 int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data);
1636 if (rslt) {
1637 // buf already contains library name
1638 if (offset) *offset = addr - data.base;
1639 return true;
1640 } else if (dladdr((void*)addr, &dlinfo)){
1641 if (buf) jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname);
1642 if (offset) *offset = addr - (address)dlinfo.dli_fbase;
1643 return true;
1644 } else {
1645 if (buf) buf[0] = '\0';
1646 if (offset) *offset = -1;
1647 return false;
1648 }
1649 }
1651 // Loads .dll/.so and
1652 // in case of error it checks if .dll/.so was built for the
1653 // same architecture as Hotspot is running on
1655 void * os::dll_load(const char *filename, char *ebuf, int ebuflen)
1656 {
1657 void * result= ::dlopen(filename, RTLD_LAZY);
1658 if (result != NULL) {
1659 // Successful loading
1660 return result;
1661 }
1663 Elf32_Ehdr elf_head;
1665 // Read system error message into ebuf
1666 // It may or may not be overwritten below
1667 ::strncpy(ebuf, ::dlerror(), ebuflen-1);
1668 ebuf[ebuflen-1]='\0';
1669 int diag_msg_max_length=ebuflen-strlen(ebuf);
1670 char* diag_msg_buf=ebuf+strlen(ebuf);
1672 if (diag_msg_max_length==0) {
1673 // No more space in ebuf for additional diagnostics message
1674 return NULL;
1675 }
1678 int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK);
1680 if (file_descriptor < 0) {
1681 // Can't open library, report dlerror() message
1682 return NULL;
1683 }
1685 bool failed_to_read_elf_head=
1686 (sizeof(elf_head)!=
1687 (::read(file_descriptor, &elf_head,sizeof(elf_head)))) ;
1689 ::close(file_descriptor);
1690 if (failed_to_read_elf_head) {
1691 // file i/o error - report dlerror() msg
1692 return NULL;
1693 }
1695 typedef struct {
1696 Elf32_Half code; // Actual value as defined in elf.h
1697 Elf32_Half compat_class; // Compatibility of archs at VM's sense
1698 char elf_class; // 32 or 64 bit
1699 char endianess; // MSB or LSB
1700 char* name; // String representation
1701 } arch_t;
1703 #ifndef EM_486
1704 #define EM_486 6 /* Intel 80486 */
1705 #endif
1707 static const arch_t arch_array[]={
1708 {EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
1709 {EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
1710 {EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"},
1711 {EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"},
1712 {EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
1713 {EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
1714 {EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"},
1715 {EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"},
1716 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"}
1717 };
1719 #if (defined IA32)
1720 static Elf32_Half running_arch_code=EM_386;
1721 #elif (defined AMD64)
1722 static Elf32_Half running_arch_code=EM_X86_64;
1723 #elif (defined IA64)
1724 static Elf32_Half running_arch_code=EM_IA_64;
1725 #elif (defined __sparc) && (defined _LP64)
1726 static Elf32_Half running_arch_code=EM_SPARCV9;
1727 #elif (defined __sparc) && (!defined _LP64)
1728 static Elf32_Half running_arch_code=EM_SPARC;
1729 #elif (defined __powerpc64__)
1730 static Elf32_Half running_arch_code=EM_PPC64;
1731 #elif (defined __powerpc__)
1732 static Elf32_Half running_arch_code=EM_PPC;
1733 #else
1734 #error Method os::dll_load requires that one of following is defined:\
1735 IA32, AMD64, IA64, __sparc, __powerpc__
1736 #endif
1738 // Identify compatability class for VM's architecture and library's architecture
1739 // Obtain string descriptions for architectures
1741 arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL};
1742 int running_arch_index=-1;
1744 for (unsigned int i=0 ; i < ARRAY_SIZE(arch_array) ; i++ ) {
1745 if (running_arch_code == arch_array[i].code) {
1746 running_arch_index = i;
1747 }
1748 if (lib_arch.code == arch_array[i].code) {
1749 lib_arch.compat_class = arch_array[i].compat_class;
1750 lib_arch.name = arch_array[i].name;
1751 }
1752 }
1754 assert(running_arch_index != -1,
1755 "Didn't find running architecture code (running_arch_code) in arch_array");
1756 if (running_arch_index == -1) {
1757 // Even though running architecture detection failed
1758 // we may still continue with reporting dlerror() message
1759 return NULL;
1760 }
1762 if (lib_arch.endianess != arch_array[running_arch_index].endianess) {
1763 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)");
1764 return NULL;
1765 }
1767 if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) {
1768 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)");
1769 return NULL;
1770 }
1772 if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) {
1773 if ( lib_arch.name!=NULL ) {
1774 ::snprintf(diag_msg_buf, diag_msg_max_length-1,
1775 " (Possible cause: can't load %s-bit .so on a %s-bit platform)",
1776 lib_arch.name, arch_array[running_arch_index].name);
1777 } else {
1778 ::snprintf(diag_msg_buf, diag_msg_max_length-1,
1779 " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)",
1780 lib_arch.code,
1781 arch_array[running_arch_index].name);
1782 }
1783 }
1785 return NULL;
1786 }
1788 /*
1789 * glibc-2.0 libdl is not MT safe. If you are building with any glibc,
1790 * chances are you might want to run the generated bits against glibc-2.0
1791 * libdl.so, so always use locking for any version of glibc.
1792 */
1793 void* os::dll_lookup(void* handle, const char* name) {
1794 pthread_mutex_lock(&dl_mutex);
1795 void* res = dlsym(handle, name);
1796 pthread_mutex_unlock(&dl_mutex);
1797 return res;
1798 }
1801 bool _print_ascii_file(const char* filename, outputStream* st) {
1802 int fd = open(filename, O_RDONLY);
1803 if (fd == -1) {
1804 return false;
1805 }
1807 char buf[32];
1808 int bytes;
1809 while ((bytes = read(fd, buf, sizeof(buf))) > 0) {
1810 st->print_raw(buf, bytes);
1811 }
1813 close(fd);
1815 return true;
1816 }
1818 void os::print_dll_info(outputStream *st) {
1819 st->print_cr("Dynamic libraries:");
1821 char fname[32];
1822 pid_t pid = os::Linux::gettid();
1824 jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid);
1826 if (!_print_ascii_file(fname, st)) {
1827 st->print("Can not get library information for pid = %d\n", pid);
1828 }
1829 }
1832 void os::print_os_info(outputStream* st) {
1833 st->print("OS:");
1835 // Try to identify popular distros.
1836 // Most Linux distributions have /etc/XXX-release file, which contains
1837 // the OS version string. Some have more than one /etc/XXX-release file
1838 // (e.g. Mandrake has both /etc/mandrake-release and /etc/redhat-release.),
1839 // so the order is important.
1840 if (!_print_ascii_file("/etc/mandrake-release", st) &&
1841 !_print_ascii_file("/etc/sun-release", st) &&
1842 !_print_ascii_file("/etc/redhat-release", st) &&
1843 !_print_ascii_file("/etc/SuSE-release", st) &&
1844 !_print_ascii_file("/etc/turbolinux-release", st) &&
1845 !_print_ascii_file("/etc/gentoo-release", st) &&
1846 !_print_ascii_file("/etc/debian_version", st)) {
1847 st->print("Linux");
1848 }
1849 st->cr();
1851 // kernel
1852 st->print("uname:");
1853 struct utsname name;
1854 uname(&name);
1855 st->print(name.sysname); st->print(" ");
1856 st->print(name.release); st->print(" ");
1857 st->print(name.version); st->print(" ");
1858 st->print(name.machine);
1859 st->cr();
1861 // Print warning if unsafe chroot environment detected
1862 if (unsafe_chroot_detected) {
1863 st->print("WARNING!! ");
1864 st->print_cr(unstable_chroot_error);
1865 }
1867 // libc, pthread
1868 st->print("libc:");
1869 st->print(os::Linux::glibc_version()); st->print(" ");
1870 st->print(os::Linux::libpthread_version()); st->print(" ");
1871 if (os::Linux::is_LinuxThreads()) {
1872 st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed");
1873 }
1874 st->cr();
1876 // rlimit
1877 st->print("rlimit:");
1878 struct rlimit rlim;
1880 st->print(" STACK ");
1881 getrlimit(RLIMIT_STACK, &rlim);
1882 if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity");
1883 else st->print("%uk", rlim.rlim_cur >> 10);
1885 st->print(", CORE ");
1886 getrlimit(RLIMIT_CORE, &rlim);
1887 if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity");
1888 else st->print("%uk", rlim.rlim_cur >> 10);
1890 st->print(", NPROC ");
1891 getrlimit(RLIMIT_NPROC, &rlim);
1892 if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity");
1893 else st->print("%d", rlim.rlim_cur);
1895 st->print(", NOFILE ");
1896 getrlimit(RLIMIT_NOFILE, &rlim);
1897 if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity");
1898 else st->print("%d", rlim.rlim_cur);
1900 st->print(", AS ");
1901 getrlimit(RLIMIT_AS, &rlim);
1902 if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity");
1903 else st->print("%uk", rlim.rlim_cur >> 10);
1904 st->cr();
1906 // load average
1907 st->print("load average:");
1908 double loadavg[3];
1909 os::loadavg(loadavg, 3);
1910 st->print("%0.02f %0.02f %0.02f", loadavg[0], loadavg[1], loadavg[2]);
1911 st->cr();
1912 }
1914 void os::print_memory_info(outputStream* st) {
1916 st->print("Memory:");
1917 st->print(" %dk page", os::vm_page_size()>>10);
1919 // values in struct sysinfo are "unsigned long"
1920 struct sysinfo si;
1921 sysinfo(&si);
1923 st->print(", physical " UINT64_FORMAT "k",
1924 os::physical_memory() >> 10);
1925 st->print("(" UINT64_FORMAT "k free)",
1926 os::available_memory() >> 10);
1927 st->print(", swap " UINT64_FORMAT "k",
1928 ((jlong)si.totalswap * si.mem_unit) >> 10);
1929 st->print("(" UINT64_FORMAT "k free)",
1930 ((jlong)si.freeswap * si.mem_unit) >> 10);
1931 st->cr();
1932 }
1934 // Taken from /usr/include/bits/siginfo.h Supposed to be architecture specific
1935 // but they're the same for all the linux arch that we support
1936 // and they're the same for solaris but there's no common place to put this.
1937 const char *ill_names[] = { "ILL0", "ILL_ILLOPC", "ILL_ILLOPN", "ILL_ILLADR",
1938 "ILL_ILLTRP", "ILL_PRVOPC", "ILL_PRVREG",
1939 "ILL_COPROC", "ILL_BADSTK" };
1941 const char *fpe_names[] = { "FPE0", "FPE_INTDIV", "FPE_INTOVF", "FPE_FLTDIV",
1942 "FPE_FLTOVF", "FPE_FLTUND", "FPE_FLTRES",
1943 "FPE_FLTINV", "FPE_FLTSUB", "FPE_FLTDEN" };
1945 const char *segv_names[] = { "SEGV0", "SEGV_MAPERR", "SEGV_ACCERR" };
1947 const char *bus_names[] = { "BUS0", "BUS_ADRALN", "BUS_ADRERR", "BUS_OBJERR" };
1949 void os::print_siginfo(outputStream* st, void* siginfo) {
1950 st->print("siginfo:");
1952 const int buflen = 100;
1953 char buf[buflen];
1954 siginfo_t *si = (siginfo_t*)siginfo;
1955 st->print("si_signo=%s: ", os::exception_name(si->si_signo, buf, buflen));
1956 if (si->si_errno != 0 && strerror_r(si->si_errno, buf, buflen) == 0) {
1957 st->print("si_errno=%s", buf);
1958 } else {
1959 st->print("si_errno=%d", si->si_errno);
1960 }
1961 const int c = si->si_code;
1962 assert(c > 0, "unexpected si_code");
1963 switch (si->si_signo) {
1964 case SIGILL:
1965 st->print(", si_code=%d (%s)", c, c > 8 ? "" : ill_names[c]);
1966 st->print(", si_addr=" PTR_FORMAT, si->si_addr);
1967 break;
1968 case SIGFPE:
1969 st->print(", si_code=%d (%s)", c, c > 9 ? "" : fpe_names[c]);
1970 st->print(", si_addr=" PTR_FORMAT, si->si_addr);
1971 break;
1972 case SIGSEGV:
1973 st->print(", si_code=%d (%s)", c, c > 2 ? "" : segv_names[c]);
1974 st->print(", si_addr=" PTR_FORMAT, si->si_addr);
1975 break;
1976 case SIGBUS:
1977 st->print(", si_code=%d (%s)", c, c > 3 ? "" : bus_names[c]);
1978 st->print(", si_addr=" PTR_FORMAT, si->si_addr);
1979 break;
1980 default:
1981 st->print(", si_code=%d", si->si_code);
1982 // no si_addr
1983 }
1985 if ((si->si_signo == SIGBUS || si->si_signo == SIGSEGV) &&
1986 UseSharedSpaces) {
1987 FileMapInfo* mapinfo = FileMapInfo::current_info();
1988 if (mapinfo->is_in_shared_space(si->si_addr)) {
1989 st->print("\n\nError accessing class data sharing archive." \
1990 " Mapped file inaccessible during execution, " \
1991 " possible disk/network problem.");
1992 }
1993 }
1994 st->cr();
1995 }
1998 static void print_signal_handler(outputStream* st, int sig,
1999 char* buf, size_t buflen);
2001 void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) {
2002 st->print_cr("Signal Handlers:");
2003 print_signal_handler(st, SIGSEGV, buf, buflen);
2004 print_signal_handler(st, SIGBUS , buf, buflen);
2005 print_signal_handler(st, SIGFPE , buf, buflen);
2006 print_signal_handler(st, SIGPIPE, buf, buflen);
2007 print_signal_handler(st, SIGXFSZ, buf, buflen);
2008 print_signal_handler(st, SIGILL , buf, buflen);
2009 print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen);
2010 print_signal_handler(st, SR_signum, buf, buflen);
2011 print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen);
2012 print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen);
2013 print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen);
2014 print_signal_handler(st, BREAK_SIGNAL, buf, buflen);
2015 }
2017 static char saved_jvm_path[MAXPATHLEN] = {0};
2019 // Find the full path to the current module, libjvm.so or libjvm_g.so
2020 void os::jvm_path(char *buf, jint len) {
2021 // Error checking.
2022 if (len < MAXPATHLEN) {
2023 assert(false, "must use a large-enough buffer");
2024 buf[0] = '\0';
2025 return;
2026 }
2027 // Lazy resolve the path to current module.
2028 if (saved_jvm_path[0] != 0) {
2029 strcpy(buf, saved_jvm_path);
2030 return;
2031 }
2033 char dli_fname[MAXPATHLEN];
2034 bool ret = dll_address_to_library_name(
2035 CAST_FROM_FN_PTR(address, os::jvm_path),
2036 dli_fname, sizeof(dli_fname), NULL);
2037 assert(ret != 0, "cannot locate libjvm");
2038 if (realpath(dli_fname, buf) == NULL)
2039 return;
2041 if (strcmp(Arguments::sun_java_launcher(), "gamma") == 0) {
2042 // Support for the gamma launcher. Typical value for buf is
2043 // "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so". If "/jre/lib/" appears at
2044 // the right place in the string, then assume we are installed in a JDK and
2045 // we're done. Otherwise, check for a JAVA_HOME environment variable and fix
2046 // up the path so it looks like libjvm.so is installed there (append a
2047 // fake suffix hotspot/libjvm.so).
2048 const char *p = buf + strlen(buf) - 1;
2049 for (int count = 0; p > buf && count < 5; ++count) {
2050 for (--p; p > buf && *p != '/'; --p)
2051 /* empty */ ;
2052 }
2054 if (strncmp(p, "/jre/lib/", 9) != 0) {
2055 // Look for JAVA_HOME in the environment.
2056 char* java_home_var = ::getenv("JAVA_HOME");
2057 if (java_home_var != NULL && java_home_var[0] != 0) {
2058 // Check the current module name "libjvm.so" or "libjvm_g.so".
2059 p = strrchr(buf, '/');
2060 assert(strstr(p, "/libjvm") == p, "invalid library name");
2061 p = strstr(p, "_g") ? "_g" : "";
2063 if (realpath(java_home_var, buf) == NULL)
2064 return;
2065 sprintf(buf + strlen(buf), "/jre/lib/%s", cpu_arch);
2066 if (0 == access(buf, F_OK)) {
2067 // Use current module name "libjvm[_g].so" instead of
2068 // "libjvm"debug_only("_g")".so" since for fastdebug version
2069 // we should have "libjvm.so" but debug_only("_g") adds "_g"!
2070 // It is used when we are choosing the HPI library's name
2071 // "libhpi[_g].so" in hpi::initialize_get_interface().
2072 sprintf(buf + strlen(buf), "/hotspot/libjvm%s.so", p);
2073 } else {
2074 // Go back to path of .so
2075 if (realpath(dli_fname, buf) == NULL)
2076 return;
2077 }
2078 }
2079 }
2080 }
2082 strcpy(saved_jvm_path, buf);
2083 }
2085 void os::print_jni_name_prefix_on(outputStream* st, int args_size) {
2086 // no prefix required, not even "_"
2087 }
2089 void os::print_jni_name_suffix_on(outputStream* st, int args_size) {
2090 // no suffix required
2091 }
2093 ////////////////////////////////////////////////////////////////////////////////
2094 // sun.misc.Signal support
2096 static volatile jint sigint_count = 0;
2098 static void
2099 UserHandler(int sig, void *siginfo, void *context) {
2100 // 4511530 - sem_post is serialized and handled by the manager thread. When
2101 // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We
2102 // don't want to flood the manager thread with sem_post requests.
2103 if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1)
2104 return;
2106 // Ctrl-C is pressed during error reporting, likely because the error
2107 // handler fails to abort. Let VM die immediately.
2108 if (sig == SIGINT && is_error_reported()) {
2109 os::die();
2110 }
2112 os::signal_notify(sig);
2113 }
2115 void* os::user_handler() {
2116 return CAST_FROM_FN_PTR(void*, UserHandler);
2117 }
2119 extern "C" {
2120 typedef void (*sa_handler_t)(int);
2121 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *);
2122 }
2124 void* os::signal(int signal_number, void* handler) {
2125 struct sigaction sigAct, oldSigAct;
2127 sigfillset(&(sigAct.sa_mask));
2128 sigAct.sa_flags = SA_RESTART|SA_SIGINFO;
2129 sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler);
2131 if (sigaction(signal_number, &sigAct, &oldSigAct)) {
2132 // -1 means registration failed
2133 return (void *)-1;
2134 }
2136 return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler);
2137 }
2139 void os::signal_raise(int signal_number) {
2140 ::raise(signal_number);
2141 }
2143 /*
2144 * The following code is moved from os.cpp for making this
2145 * code platform specific, which it is by its very nature.
2146 */
2148 // Will be modified when max signal is changed to be dynamic
2149 int os::sigexitnum_pd() {
2150 return NSIG;
2151 }
2153 // a counter for each possible signal value
2154 static volatile jint pending_signals[NSIG+1] = { 0 };
2156 // Linux(POSIX) specific hand shaking semaphore.
2157 static sem_t sig_sem;
2159 void os::signal_init_pd() {
2160 // Initialize signal structures
2161 ::memset((void*)pending_signals, 0, sizeof(pending_signals));
2163 // Initialize signal semaphore
2164 ::sem_init(&sig_sem, 0, 0);
2165 }
2167 void os::signal_notify(int sig) {
2168 Atomic::inc(&pending_signals[sig]);
2169 ::sem_post(&sig_sem);
2170 }
2172 static int check_pending_signals(bool wait) {
2173 Atomic::store(0, &sigint_count);
2174 for (;;) {
2175 for (int i = 0; i < NSIG + 1; i++) {
2176 jint n = pending_signals[i];
2177 if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) {
2178 return i;
2179 }
2180 }
2181 if (!wait) {
2182 return -1;
2183 }
2184 JavaThread *thread = JavaThread::current();
2185 ThreadBlockInVM tbivm(thread);
2187 bool threadIsSuspended;
2188 do {
2189 thread->set_suspend_equivalent();
2190 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
2191 ::sem_wait(&sig_sem);
2193 // were we externally suspended while we were waiting?
2194 threadIsSuspended = thread->handle_special_suspend_equivalent_condition();
2195 if (threadIsSuspended) {
2196 //
2197 // The semaphore has been incremented, but while we were waiting
2198 // another thread suspended us. We don't want to continue running
2199 // while suspended because that would surprise the thread that
2200 // suspended us.
2201 //
2202 ::sem_post(&sig_sem);
2204 thread->java_suspend_self();
2205 }
2206 } while (threadIsSuspended);
2207 }
2208 }
2210 int os::signal_lookup() {
2211 return check_pending_signals(false);
2212 }
2214 int os::signal_wait() {
2215 return check_pending_signals(true);
2216 }
2218 ////////////////////////////////////////////////////////////////////////////////
2219 // Virtual Memory
2221 int os::vm_page_size() {
2222 // Seems redundant as all get out
2223 assert(os::Linux::page_size() != -1, "must call os::init");
2224 return os::Linux::page_size();
2225 }
2227 // Solaris allocates memory by pages.
2228 int os::vm_allocation_granularity() {
2229 assert(os::Linux::page_size() != -1, "must call os::init");
2230 return os::Linux::page_size();
2231 }
2233 // Rationale behind this function:
2234 // current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable
2235 // mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get
2236 // samples for JITted code. Here we create private executable mapping over the code cache
2237 // and then we can use standard (well, almost, as mapping can change) way to provide
2238 // info for the reporting script by storing timestamp and location of symbol
2239 void linux_wrap_code(char* base, size_t size) {
2240 static volatile jint cnt = 0;
2242 if (!UseOprofile) {
2243 return;
2244 }
2246 char buf[40];
2247 int num = Atomic::add(1, &cnt);
2249 sprintf(buf, "/tmp/hs-vm-%d-%d", os::current_process_id(), num);
2250 unlink(buf);
2252 int fd = open(buf, O_CREAT | O_RDWR, S_IRWXU);
2254 if (fd != -1) {
2255 off_t rv = lseek(fd, size-2, SEEK_SET);
2256 if (rv != (off_t)-1) {
2257 if (write(fd, "", 1) == 1) {
2258 mmap(base, size,
2259 PROT_READ|PROT_WRITE|PROT_EXEC,
2260 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0);
2261 }
2262 }
2263 close(fd);
2264 unlink(buf);
2265 }
2266 }
2268 // NOTE: Linux kernel does not really reserve the pages for us.
2269 // All it does is to check if there are enough free pages
2270 // left at the time of mmap(). This could be a potential
2271 // problem.
2272 bool os::commit_memory(char* addr, size_t size) {
2273 uintptr_t res = (uintptr_t) ::mmap(addr, size,
2274 PROT_READ|PROT_WRITE|PROT_EXEC,
2275 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0);
2276 return res != (uintptr_t) MAP_FAILED;
2277 }
2279 bool os::commit_memory(char* addr, size_t size, size_t alignment_hint) {
2280 return commit_memory(addr, size);
2281 }
2283 void os::realign_memory(char *addr, size_t bytes, size_t alignment_hint) { }
2285 void os::free_memory(char *addr, size_t bytes) {
2286 uncommit_memory(addr, bytes);
2287 }
2289 void os::numa_make_global(char *addr, size_t bytes) {
2290 Linux::numa_interleave_memory(addr, bytes);
2291 }
2293 void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) {
2294 Linux::numa_tonode_memory(addr, bytes, lgrp_hint);
2295 }
2297 bool os::numa_topology_changed() { return false; }
2299 size_t os::numa_get_groups_num() {
2300 int max_node = Linux::numa_max_node();
2301 return max_node > 0 ? max_node + 1 : 1;
2302 }
2304 int os::numa_get_group_id() {
2305 int cpu_id = Linux::sched_getcpu();
2306 if (cpu_id != -1) {
2307 int lgrp_id = Linux::get_node_by_cpu(cpu_id);
2308 if (lgrp_id != -1) {
2309 return lgrp_id;
2310 }
2311 }
2312 return 0;
2313 }
2315 size_t os::numa_get_leaf_groups(int *ids, size_t size) {
2316 for (size_t i = 0; i < size; i++) {
2317 ids[i] = i;
2318 }
2319 return size;
2320 }
2322 bool os::get_page_info(char *start, page_info* info) {
2323 return false;
2324 }
2326 char *os::scan_pages(char *start, char* end, page_info* page_expected, page_info* page_found) {
2327 return end;
2328 }
2330 extern "C" void numa_warn(int number, char *where, ...) { }
2331 extern "C" void numa_error(char *where) { }
2333 bool os::Linux::libnuma_init() {
2334 // sched_getcpu() should be in libc.
2335 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t,
2336 dlsym(RTLD_DEFAULT, "sched_getcpu")));
2338 if (sched_getcpu() != -1) { // Does it work?
2339 void *handle = dlopen("libnuma.so.1", RTLD_LAZY);
2340 if (handle != NULL) {
2341 set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t,
2342 dlsym(handle, "numa_node_to_cpus")));
2343 set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t,
2344 dlsym(handle, "numa_max_node")));
2345 set_numa_available(CAST_TO_FN_PTR(numa_available_func_t,
2346 dlsym(handle, "numa_available")));
2347 set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t,
2348 dlsym(handle, "numa_tonode_memory")));
2349 set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t,
2350 dlsym(handle, "numa_interleave_memory")));
2353 if (numa_available() != -1) {
2354 set_numa_all_nodes((unsigned long*)dlsym(handle, "numa_all_nodes"));
2355 // Create a cpu -> node mapping
2356 _cpu_to_node = new (ResourceObj::C_HEAP) GrowableArray<int>(0, true);
2357 rebuild_cpu_to_node_map();
2358 return true;
2359 }
2360 }
2361 }
2362 return false;
2363 }
2365 // rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id.
2366 // The table is later used in get_node_by_cpu().
2367 void os::Linux::rebuild_cpu_to_node_map() {
2368 const size_t NCPUS = 32768; // Since the buffer size computation is very obscure
2369 // in libnuma (possible values are starting from 16,
2370 // and continuing up with every other power of 2, but less
2371 // than the maximum number of CPUs supported by kernel), and
2372 // is a subject to change (in libnuma version 2 the requirements
2373 // are more reasonable) we'll just hardcode the number they use
2374 // in the library.
2375 const size_t BitsPerCLong = sizeof(long) * CHAR_BIT;
2377 size_t cpu_num = os::active_processor_count();
2378 size_t cpu_map_size = NCPUS / BitsPerCLong;
2379 size_t cpu_map_valid_size =
2380 MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size);
2382 cpu_to_node()->clear();
2383 cpu_to_node()->at_grow(cpu_num - 1);
2384 size_t node_num = numa_get_groups_num();
2386 unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size);
2387 for (size_t i = 0; i < node_num; i++) {
2388 if (numa_node_to_cpus(i, cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) {
2389 for (size_t j = 0; j < cpu_map_valid_size; j++) {
2390 if (cpu_map[j] != 0) {
2391 for (size_t k = 0; k < BitsPerCLong; k++) {
2392 if (cpu_map[j] & (1UL << k)) {
2393 cpu_to_node()->at_put(j * BitsPerCLong + k, i);
2394 }
2395 }
2396 }
2397 }
2398 }
2399 }
2400 FREE_C_HEAP_ARRAY(unsigned long, cpu_map);
2401 }
2403 int os::Linux::get_node_by_cpu(int cpu_id) {
2404 if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) {
2405 return cpu_to_node()->at(cpu_id);
2406 }
2407 return -1;
2408 }
2410 GrowableArray<int>* os::Linux::_cpu_to_node;
2411 os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu;
2412 os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus;
2413 os::Linux::numa_max_node_func_t os::Linux::_numa_max_node;
2414 os::Linux::numa_available_func_t os::Linux::_numa_available;
2415 os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory;
2416 os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory;
2417 unsigned long* os::Linux::_numa_all_nodes;
2419 bool os::uncommit_memory(char* addr, size_t size) {
2420 return ::mmap(addr, size,
2421 PROT_READ|PROT_WRITE|PROT_EXEC,
2422 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0)
2423 != MAP_FAILED;
2424 }
2426 static address _highest_vm_reserved_address = NULL;
2428 // If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory
2429 // at 'requested_addr'. If there are existing memory mappings at the same
2430 // location, however, they will be overwritten. If 'fixed' is false,
2431 // 'requested_addr' is only treated as a hint, the return value may or
2432 // may not start from the requested address. Unlike Linux mmap(), this
2433 // function returns NULL to indicate failure.
2434 static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) {
2435 char * addr;
2436 int flags;
2438 flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS;
2439 if (fixed) {
2440 assert((uintptr_t)requested_addr % os::Linux::page_size() == 0, "unaligned address");
2441 flags |= MAP_FIXED;
2442 }
2444 addr = (char*)::mmap(requested_addr, bytes, PROT_READ|PROT_WRITE|PROT_EXEC,
2445 flags, -1, 0);
2447 if (addr != MAP_FAILED) {
2448 // anon_mmap() should only get called during VM initialization,
2449 // don't need lock (actually we can skip locking even it can be called
2450 // from multiple threads, because _highest_vm_reserved_address is just a
2451 // hint about the upper limit of non-stack memory regions.)
2452 if ((address)addr + bytes > _highest_vm_reserved_address) {
2453 _highest_vm_reserved_address = (address)addr + bytes;
2454 }
2455 }
2457 return addr == MAP_FAILED ? NULL : addr;
2458 }
2460 // Don't update _highest_vm_reserved_address, because there might be memory
2461 // regions above addr + size. If so, releasing a memory region only creates
2462 // a hole in the address space, it doesn't help prevent heap-stack collision.
2463 //
2464 static int anon_munmap(char * addr, size_t size) {
2465 return ::munmap(addr, size) == 0;
2466 }
2468 char* os::reserve_memory(size_t bytes, char* requested_addr,
2469 size_t alignment_hint) {
2470 return anon_mmap(requested_addr, bytes, (requested_addr != NULL));
2471 }
2473 bool os::release_memory(char* addr, size_t size) {
2474 return anon_munmap(addr, size);
2475 }
2477 static address highest_vm_reserved_address() {
2478 return _highest_vm_reserved_address;
2479 }
2481 static bool linux_mprotect(char* addr, size_t size, int prot) {
2482 // Linux wants the mprotect address argument to be page aligned.
2483 char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::page_size());
2485 // According to SUSv3, mprotect() should only be used with mappings
2486 // established by mmap(), and mmap() always maps whole pages. Unaligned
2487 // 'addr' likely indicates problem in the VM (e.g. trying to change
2488 // protection of malloc'ed or statically allocated memory). Check the
2489 // caller if you hit this assert.
2490 assert(addr == bottom, "sanity check");
2492 size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Linux::page_size());
2493 return ::mprotect(bottom, size, prot) == 0;
2494 }
2496 // Set protections specified
2497 bool os::protect_memory(char* addr, size_t bytes, ProtType prot,
2498 bool is_committed) {
2499 unsigned int p = 0;
2500 switch (prot) {
2501 case MEM_PROT_NONE: p = PROT_NONE; break;
2502 case MEM_PROT_READ: p = PROT_READ; break;
2503 case MEM_PROT_RW: p = PROT_READ|PROT_WRITE; break;
2504 case MEM_PROT_RWX: p = PROT_READ|PROT_WRITE|PROT_EXEC; break;
2505 default:
2506 ShouldNotReachHere();
2507 }
2508 // is_committed is unused.
2509 return linux_mprotect(addr, bytes, p);
2510 }
2512 bool os::guard_memory(char* addr, size_t size) {
2513 return linux_mprotect(addr, size, PROT_NONE);
2514 }
2516 bool os::unguard_memory(char* addr, size_t size) {
2517 return linux_mprotect(addr, size, PROT_READ|PROT_WRITE);
2518 }
2520 // Large page support
2522 static size_t _large_page_size = 0;
2524 bool os::large_page_init() {
2525 if (!UseLargePages) return false;
2527 if (LargePageSizeInBytes) {
2528 _large_page_size = LargePageSizeInBytes;
2529 } else {
2530 // large_page_size on Linux is used to round up heap size. x86 uses either
2531 // 2M or 4M page, depending on whether PAE (Physical Address Extensions)
2532 // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use
2533 // page as large as 256M.
2534 //
2535 // Here we try to figure out page size by parsing /proc/meminfo and looking
2536 // for a line with the following format:
2537 // Hugepagesize: 2048 kB
2538 //
2539 // If we can't determine the value (e.g. /proc is not mounted, or the text
2540 // format has been changed), we'll use the largest page size supported by
2541 // the processor.
2543 _large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M);
2545 FILE *fp = fopen("/proc/meminfo", "r");
2546 if (fp) {
2547 while (!feof(fp)) {
2548 int x = 0;
2549 char buf[16];
2550 if (fscanf(fp, "Hugepagesize: %d", &x) == 1) {
2551 if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) {
2552 _large_page_size = x * K;
2553 break;
2554 }
2555 } else {
2556 // skip to next line
2557 for (;;) {
2558 int ch = fgetc(fp);
2559 if (ch == EOF || ch == (int)'\n') break;
2560 }
2561 }
2562 }
2563 fclose(fp);
2564 }
2565 }
2567 const size_t default_page_size = (size_t)Linux::page_size();
2568 if (_large_page_size > default_page_size) {
2569 _page_sizes[0] = _large_page_size;
2570 _page_sizes[1] = default_page_size;
2571 _page_sizes[2] = 0;
2572 }
2574 // Large page support is available on 2.6 or newer kernel, some vendors
2575 // (e.g. Redhat) have backported it to their 2.4 based distributions.
2576 // We optimistically assume the support is available. If later it turns out
2577 // not true, VM will automatically switch to use regular page size.
2578 return true;
2579 }
2581 #ifndef SHM_HUGETLB
2582 #define SHM_HUGETLB 04000
2583 #endif
2585 char* os::reserve_memory_special(size_t bytes) {
2586 assert(UseLargePages, "only for large pages");
2588 key_t key = IPC_PRIVATE;
2589 char *addr;
2591 bool warn_on_failure = UseLargePages &&
2592 (!FLAG_IS_DEFAULT(UseLargePages) ||
2593 !FLAG_IS_DEFAULT(LargePageSizeInBytes)
2594 );
2595 char msg[128];
2597 // Create a large shared memory region to attach to based on size.
2598 // Currently, size is the total size of the heap
2599 int shmid = shmget(key, bytes, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W);
2600 if (shmid == -1) {
2601 // Possible reasons for shmget failure:
2602 // 1. shmmax is too small for Java heap.
2603 // > check shmmax value: cat /proc/sys/kernel/shmmax
2604 // > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax
2605 // 2. not enough large page memory.
2606 // > check available large pages: cat /proc/meminfo
2607 // > increase amount of large pages:
2608 // echo new_value > /proc/sys/vm/nr_hugepages
2609 // Note 1: different Linux may use different name for this property,
2610 // e.g. on Redhat AS-3 it is "hugetlb_pool".
2611 // Note 2: it's possible there's enough physical memory available but
2612 // they are so fragmented after a long run that they can't
2613 // coalesce into large pages. Try to reserve large pages when
2614 // the system is still "fresh".
2615 if (warn_on_failure) {
2616 jio_snprintf(msg, sizeof(msg), "Failed to reserve shared memory (errno = %d).", errno);
2617 warning(msg);
2618 }
2619 return NULL;
2620 }
2622 // attach to the region
2623 addr = (char*)shmat(shmid, NULL, 0);
2624 int err = errno;
2626 // Remove shmid. If shmat() is successful, the actual shared memory segment
2627 // will be deleted when it's detached by shmdt() or when the process
2628 // terminates. If shmat() is not successful this will remove the shared
2629 // segment immediately.
2630 shmctl(shmid, IPC_RMID, NULL);
2632 if ((intptr_t)addr == -1) {
2633 if (warn_on_failure) {
2634 jio_snprintf(msg, sizeof(msg), "Failed to attach shared memory (errno = %d).", err);
2635 warning(msg);
2636 }
2637 return NULL;
2638 }
2640 return addr;
2641 }
2643 bool os::release_memory_special(char* base, size_t bytes) {
2644 // detaching the SHM segment will also delete it, see reserve_memory_special()
2645 int rslt = shmdt(base);
2646 return rslt == 0;
2647 }
2649 size_t os::large_page_size() {
2650 return _large_page_size;
2651 }
2653 // Linux does not support anonymous mmap with large page memory. The only way
2654 // to reserve large page memory without file backing is through SysV shared
2655 // memory API. The entire memory region is committed and pinned upfront.
2656 // Hopefully this will change in the future...
2657 bool os::can_commit_large_page_memory() {
2658 return false;
2659 }
2661 bool os::can_execute_large_page_memory() {
2662 return false;
2663 }
2665 // Reserve memory at an arbitrary address, only if that area is
2666 // available (and not reserved for something else).
2668 char* os::attempt_reserve_memory_at(size_t bytes, char* requested_addr) {
2669 const int max_tries = 10;
2670 char* base[max_tries];
2671 size_t size[max_tries];
2672 const size_t gap = 0x000000;
2674 // Assert only that the size is a multiple of the page size, since
2675 // that's all that mmap requires, and since that's all we really know
2676 // about at this low abstraction level. If we need higher alignment,
2677 // we can either pass an alignment to this method or verify alignment
2678 // in one of the methods further up the call chain. See bug 5044738.
2679 assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block");
2681 // Repeatedly allocate blocks until the block is allocated at the
2682 // right spot. Give up after max_tries. Note that reserve_memory() will
2683 // automatically update _highest_vm_reserved_address if the call is
2684 // successful. The variable tracks the highest memory address every reserved
2685 // by JVM. It is used to detect heap-stack collision if running with
2686 // fixed-stack LinuxThreads. Because here we may attempt to reserve more
2687 // space than needed, it could confuse the collision detecting code. To
2688 // solve the problem, save current _highest_vm_reserved_address and
2689 // calculate the correct value before return.
2690 address old_highest = _highest_vm_reserved_address;
2692 // Linux mmap allows caller to pass an address as hint; give it a try first,
2693 // if kernel honors the hint then we can return immediately.
2694 char * addr = anon_mmap(requested_addr, bytes, false);
2695 if (addr == requested_addr) {
2696 return requested_addr;
2697 }
2699 if (addr != NULL) {
2700 // mmap() is successful but it fails to reserve at the requested address
2701 anon_munmap(addr, bytes);
2702 }
2704 int i;
2705 for (i = 0; i < max_tries; ++i) {
2706 base[i] = reserve_memory(bytes);
2708 if (base[i] != NULL) {
2709 // Is this the block we wanted?
2710 if (base[i] == requested_addr) {
2711 size[i] = bytes;
2712 break;
2713 }
2715 // Does this overlap the block we wanted? Give back the overlapped
2716 // parts and try again.
2718 size_t top_overlap = requested_addr + (bytes + gap) - base[i];
2719 if (top_overlap >= 0 && top_overlap < bytes) {
2720 unmap_memory(base[i], top_overlap);
2721 base[i] += top_overlap;
2722 size[i] = bytes - top_overlap;
2723 } else {
2724 size_t bottom_overlap = base[i] + bytes - requested_addr;
2725 if (bottom_overlap >= 0 && bottom_overlap < bytes) {
2726 unmap_memory(requested_addr, bottom_overlap);
2727 size[i] = bytes - bottom_overlap;
2728 } else {
2729 size[i] = bytes;
2730 }
2731 }
2732 }
2733 }
2735 // Give back the unused reserved pieces.
2737 for (int j = 0; j < i; ++j) {
2738 if (base[j] != NULL) {
2739 unmap_memory(base[j], size[j]);
2740 }
2741 }
2743 if (i < max_tries) {
2744 _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes);
2745 return requested_addr;
2746 } else {
2747 _highest_vm_reserved_address = old_highest;
2748 return NULL;
2749 }
2750 }
2752 size_t os::read(int fd, void *buf, unsigned int nBytes) {
2753 return ::read(fd, buf, nBytes);
2754 }
2756 // TODO-FIXME: reconcile Solaris' os::sleep with the linux variation.
2757 // Solaris uses poll(), linux uses park().
2758 // Poll() is likely a better choice, assuming that Thread.interrupt()
2759 // generates a SIGUSRx signal. Note that SIGUSR1 can interfere with
2760 // SIGSEGV, see 4355769.
2762 const int NANOSECS_PER_MILLISECS = 1000000;
2764 int os::sleep(Thread* thread, jlong millis, bool interruptible) {
2765 assert(thread == Thread::current(), "thread consistency check");
2767 ParkEvent * const slp = thread->_SleepEvent ;
2768 slp->reset() ;
2769 OrderAccess::fence() ;
2771 if (interruptible) {
2772 jlong prevtime = javaTimeNanos();
2774 for (;;) {
2775 if (os::is_interrupted(thread, true)) {
2776 return OS_INTRPT;
2777 }
2779 jlong newtime = javaTimeNanos();
2781 if (newtime - prevtime < 0) {
2782 // time moving backwards, should only happen if no monotonic clock
2783 // not a guarantee() because JVM should not abort on kernel/glibc bugs
2784 assert(!Linux::supports_monotonic_clock(), "time moving backwards");
2785 } else {
2786 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISECS;
2787 }
2789 if(millis <= 0) {
2790 return OS_OK;
2791 }
2793 prevtime = newtime;
2795 {
2796 assert(thread->is_Java_thread(), "sanity check");
2797 JavaThread *jt = (JavaThread *) thread;
2798 ThreadBlockInVM tbivm(jt);
2799 OSThreadWaitState osts(jt->osthread(), false /* not Object.wait() */);
2801 jt->set_suspend_equivalent();
2802 // cleared by handle_special_suspend_equivalent_condition() or
2803 // java_suspend_self() via check_and_wait_while_suspended()
2805 slp->park(millis);
2807 // were we externally suspended while we were waiting?
2808 jt->check_and_wait_while_suspended();
2809 }
2810 }
2811 } else {
2812 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */);
2813 jlong prevtime = javaTimeNanos();
2815 for (;;) {
2816 // It'd be nice to avoid the back-to-back javaTimeNanos() calls on
2817 // the 1st iteration ...
2818 jlong newtime = javaTimeNanos();
2820 if (newtime - prevtime < 0) {
2821 // time moving backwards, should only happen if no monotonic clock
2822 // not a guarantee() because JVM should not abort on kernel/glibc bugs
2823 assert(!Linux::supports_monotonic_clock(), "time moving backwards");
2824 } else {
2825 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISECS;
2826 }
2828 if(millis <= 0) break ;
2830 prevtime = newtime;
2831 slp->park(millis);
2832 }
2833 return OS_OK ;
2834 }
2835 }
2837 int os::naked_sleep() {
2838 // %% make the sleep time an integer flag. for now use 1 millisec.
2839 return os::sleep(Thread::current(), 1, false);
2840 }
2842 // Sleep forever; naked call to OS-specific sleep; use with CAUTION
2843 void os::infinite_sleep() {
2844 while (true) { // sleep forever ...
2845 ::sleep(100); // ... 100 seconds at a time
2846 }
2847 }
2849 // Used to convert frequent JVM_Yield() to nops
2850 bool os::dont_yield() {
2851 return DontYieldALot;
2852 }
2854 void os::yield() {
2855 sched_yield();
2856 }
2858 os::YieldResult os::NakedYield() { sched_yield(); return os::YIELD_UNKNOWN ;}
2860 void os::yield_all(int attempts) {
2861 // Yields to all threads, including threads with lower priorities
2862 // Threads on Linux are all with same priority. The Solaris style
2863 // os::yield_all() with nanosleep(1ms) is not necessary.
2864 sched_yield();
2865 }
2867 // Called from the tight loops to possibly influence time-sharing heuristics
2868 void os::loop_breaker(int attempts) {
2869 os::yield_all(attempts);
2870 }
2872 ////////////////////////////////////////////////////////////////////////////////
2873 // thread priority support
2875 // Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER
2876 // only supports dynamic priority, static priority must be zero. For real-time
2877 // applications, Linux supports SCHED_RR which allows static priority (1-99).
2878 // However, for large multi-threaded applications, SCHED_RR is not only slower
2879 // than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out
2880 // of 5 runs - Sep 2005).
2881 //
2882 // The following code actually changes the niceness of kernel-thread/LWP. It
2883 // has an assumption that setpriority() only modifies one kernel-thread/LWP,
2884 // not the entire user process, and user level threads are 1:1 mapped to kernel
2885 // threads. It has always been the case, but could change in the future. For
2886 // this reason, the code should not be used as default (ThreadPriorityPolicy=0).
2887 // It is only used when ThreadPriorityPolicy=1 and requires root privilege.
2889 int os::java_to_os_priority[MaxPriority + 1] = {
2890 19, // 0 Entry should never be used
2892 4, // 1 MinPriority
2893 3, // 2
2894 2, // 3
2896 1, // 4
2897 0, // 5 NormPriority
2898 -1, // 6
2900 -2, // 7
2901 -3, // 8
2902 -4, // 9 NearMaxPriority
2904 -5 // 10 MaxPriority
2905 };
2907 static int prio_init() {
2908 if (ThreadPriorityPolicy == 1) {
2909 // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1
2910 // if effective uid is not root. Perhaps, a more elegant way of doing
2911 // this is to test CAP_SYS_NICE capability, but that will require libcap.so
2912 if (geteuid() != 0) {
2913 if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) {
2914 warning("-XX:ThreadPriorityPolicy requires root privilege on Linux");
2915 }
2916 ThreadPriorityPolicy = 0;
2917 }
2918 }
2919 return 0;
2920 }
2922 OSReturn os::set_native_priority(Thread* thread, int newpri) {
2923 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) return OS_OK;
2925 int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri);
2926 return (ret == 0) ? OS_OK : OS_ERR;
2927 }
2929 OSReturn os::get_native_priority(const Thread* const thread, int *priority_ptr) {
2930 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) {
2931 *priority_ptr = java_to_os_priority[NormPriority];
2932 return OS_OK;
2933 }
2935 errno = 0;
2936 *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id());
2937 return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR);
2938 }
2940 // Hint to the underlying OS that a task switch would not be good.
2941 // Void return because it's a hint and can fail.
2942 void os::hint_no_preempt() {}
2944 ////////////////////////////////////////////////////////////////////////////////
2945 // suspend/resume support
2947 // the low-level signal-based suspend/resume support is a remnant from the
2948 // old VM-suspension that used to be for java-suspension, safepoints etc,
2949 // within hotspot. Now there is a single use-case for this:
2950 // - calling get_thread_pc() on the VMThread by the flat-profiler task
2951 // that runs in the watcher thread.
2952 // The remaining code is greatly simplified from the more general suspension
2953 // code that used to be used.
2954 //
2955 // The protocol is quite simple:
2956 // - suspend:
2957 // - sends a signal to the target thread
2958 // - polls the suspend state of the osthread using a yield loop
2959 // - target thread signal handler (SR_handler) sets suspend state
2960 // and blocks in sigsuspend until continued
2961 // - resume:
2962 // - sets target osthread state to continue
2963 // - sends signal to end the sigsuspend loop in the SR_handler
2964 //
2965 // Note that the SR_lock plays no role in this suspend/resume protocol.
2966 //
2968 static void resume_clear_context(OSThread *osthread) {
2969 osthread->set_ucontext(NULL);
2970 osthread->set_siginfo(NULL);
2972 // notify the suspend action is completed, we have now resumed
2973 osthread->sr.clear_suspended();
2974 }
2976 static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo, ucontext_t* context) {
2977 osthread->set_ucontext(context);
2978 osthread->set_siginfo(siginfo);
2979 }
2981 //
2982 // Handler function invoked when a thread's execution is suspended or
2983 // resumed. We have to be careful that only async-safe functions are
2984 // called here (Note: most pthread functions are not async safe and
2985 // should be avoided.)
2986 //
2987 // Note: sigwait() is a more natural fit than sigsuspend() from an
2988 // interface point of view, but sigwait() prevents the signal hander
2989 // from being run. libpthread would get very confused by not having
2990 // its signal handlers run and prevents sigwait()'s use with the
2991 // mutex granting granting signal.
2992 //
2993 // Currently only ever called on the VMThread
2994 //
2995 static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) {
2996 // Save and restore errno to avoid confusing native code with EINTR
2997 // after sigsuspend.
2998 int old_errno = errno;
3000 Thread* thread = Thread::current();
3001 OSThread* osthread = thread->osthread();
3002 assert(thread->is_VM_thread(), "Must be VMThread");
3003 // read current suspend action
3004 int action = osthread->sr.suspend_action();
3005 if (action == SR_SUSPEND) {
3006 suspend_save_context(osthread, siginfo, context);
3008 // Notify the suspend action is about to be completed. do_suspend()
3009 // waits until SR_SUSPENDED is set and then returns. We will wait
3010 // here for a resume signal and that completes the suspend-other
3011 // action. do_suspend/do_resume is always called as a pair from
3012 // the same thread - so there are no races
3014 // notify the caller
3015 osthread->sr.set_suspended();
3017 sigset_t suspend_set; // signals for sigsuspend()
3019 // get current set of blocked signals and unblock resume signal
3020 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set);
3021 sigdelset(&suspend_set, SR_signum);
3023 // wait here until we are resumed
3024 do {
3025 sigsuspend(&suspend_set);
3026 // ignore all returns until we get a resume signal
3027 } while (osthread->sr.suspend_action() != SR_CONTINUE);
3029 resume_clear_context(osthread);
3031 } else {
3032 assert(action == SR_CONTINUE, "unexpected sr action");
3033 // nothing special to do - just leave the handler
3034 }
3036 errno = old_errno;
3037 }
3040 static int SR_initialize() {
3041 struct sigaction act;
3042 char *s;
3043 /* Get signal number to use for suspend/resume */
3044 if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) {
3045 int sig = ::strtol(s, 0, 10);
3046 if (sig > 0 || sig < _NSIG) {
3047 SR_signum = sig;
3048 }
3049 }
3051 assert(SR_signum > SIGSEGV && SR_signum > SIGBUS,
3052 "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769");
3054 sigemptyset(&SR_sigset);
3055 sigaddset(&SR_sigset, SR_signum);
3057 /* Set up signal handler for suspend/resume */
3058 act.sa_flags = SA_RESTART|SA_SIGINFO;
3059 act.sa_handler = (void (*)(int)) SR_handler;
3061 // SR_signum is blocked by default.
3062 // 4528190 - We also need to block pthread restart signal (32 on all
3063 // supported Linux platforms). Note that LinuxThreads need to block
3064 // this signal for all threads to work properly. So we don't have
3065 // to use hard-coded signal number when setting up the mask.
3066 pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask);
3068 if (sigaction(SR_signum, &act, 0) == -1) {
3069 return -1;
3070 }
3072 // Save signal flag
3073 os::Linux::set_our_sigflags(SR_signum, act.sa_flags);
3074 return 0;
3075 }
3077 static int SR_finalize() {
3078 return 0;
3079 }
3082 // returns true on success and false on error - really an error is fatal
3083 // but this seems the normal response to library errors
3084 static bool do_suspend(OSThread* osthread) {
3085 // mark as suspended and send signal
3086 osthread->sr.set_suspend_action(SR_SUSPEND);
3087 int status = pthread_kill(osthread->pthread_id(), SR_signum);
3088 assert_status(status == 0, status, "pthread_kill");
3090 // check status and wait until notified of suspension
3091 if (status == 0) {
3092 for (int i = 0; !osthread->sr.is_suspended(); i++) {
3093 os::yield_all(i);
3094 }
3095 osthread->sr.set_suspend_action(SR_NONE);
3096 return true;
3097 }
3098 else {
3099 osthread->sr.set_suspend_action(SR_NONE);
3100 return false;
3101 }
3102 }
3104 static void do_resume(OSThread* osthread) {
3105 assert(osthread->sr.is_suspended(), "thread should be suspended");
3106 osthread->sr.set_suspend_action(SR_CONTINUE);
3108 int status = pthread_kill(osthread->pthread_id(), SR_signum);
3109 assert_status(status == 0, status, "pthread_kill");
3110 // check status and wait unit notified of resumption
3111 if (status == 0) {
3112 for (int i = 0; osthread->sr.is_suspended(); i++) {
3113 os::yield_all(i);
3114 }
3115 }
3116 osthread->sr.set_suspend_action(SR_NONE);
3117 }
3119 ////////////////////////////////////////////////////////////////////////////////
3120 // interrupt support
3122 void os::interrupt(Thread* thread) {
3123 assert(Thread::current() == thread || Threads_lock->owned_by_self(),
3124 "possibility of dangling Thread pointer");
3126 OSThread* osthread = thread->osthread();
3128 if (!osthread->interrupted()) {
3129 osthread->set_interrupted(true);
3130 // More than one thread can get here with the same value of osthread,
3131 // resulting in multiple notifications. We do, however, want the store
3132 // to interrupted() to be visible to other threads before we execute unpark().
3133 OrderAccess::fence();
3134 ParkEvent * const slp = thread->_SleepEvent ;
3135 if (slp != NULL) slp->unpark() ;
3136 }
3138 // For JSR166. Unpark even if interrupt status already was set
3139 if (thread->is_Java_thread())
3140 ((JavaThread*)thread)->parker()->unpark();
3142 ParkEvent * ev = thread->_ParkEvent ;
3143 if (ev != NULL) ev->unpark() ;
3145 }
3147 bool os::is_interrupted(Thread* thread, bool clear_interrupted) {
3148 assert(Thread::current() == thread || Threads_lock->owned_by_self(),
3149 "possibility of dangling Thread pointer");
3151 OSThread* osthread = thread->osthread();
3153 bool interrupted = osthread->interrupted();
3155 if (interrupted && clear_interrupted) {
3156 osthread->set_interrupted(false);
3157 // consider thread->_SleepEvent->reset() ... optional optimization
3158 }
3160 return interrupted;
3161 }
3163 ///////////////////////////////////////////////////////////////////////////////////
3164 // signal handling (except suspend/resume)
3166 // This routine may be used by user applications as a "hook" to catch signals.
3167 // The user-defined signal handler must pass unrecognized signals to this
3168 // routine, and if it returns true (non-zero), then the signal handler must
3169 // return immediately. If the flag "abort_if_unrecognized" is true, then this
3170 // routine will never retun false (zero), but instead will execute a VM panic
3171 // routine kill the process.
3172 //
3173 // If this routine returns false, it is OK to call it again. This allows
3174 // the user-defined signal handler to perform checks either before or after
3175 // the VM performs its own checks. Naturally, the user code would be making
3176 // a serious error if it tried to handle an exception (such as a null check
3177 // or breakpoint) that the VM was generating for its own correct operation.
3178 //
3179 // This routine may recognize any of the following kinds of signals:
3180 // SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1.
3181 // It should be consulted by handlers for any of those signals.
3182 //
3183 // The caller of this routine must pass in the three arguments supplied
3184 // to the function referred to in the "sa_sigaction" (not the "sa_handler")
3185 // field of the structure passed to sigaction(). This routine assumes that
3186 // the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART.
3187 //
3188 // Note that the VM will print warnings if it detects conflicting signal
3189 // handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers".
3190 //
3191 extern "C" int
3192 JVM_handle_linux_signal(int signo, siginfo_t* siginfo,
3193 void* ucontext, int abort_if_unrecognized);
3195 void signalHandler(int sig, siginfo_t* info, void* uc) {
3196 assert(info != NULL && uc != NULL, "it must be old kernel");
3197 JVM_handle_linux_signal(sig, info, uc, true);
3198 }
3201 // This boolean allows users to forward their own non-matching signals
3202 // to JVM_handle_linux_signal, harmlessly.
3203 bool os::Linux::signal_handlers_are_installed = false;
3205 // For signal-chaining
3206 struct sigaction os::Linux::sigact[MAXSIGNUM];
3207 unsigned int os::Linux::sigs = 0;
3208 bool os::Linux::libjsig_is_loaded = false;
3209 typedef struct sigaction *(*get_signal_t)(int);
3210 get_signal_t os::Linux::get_signal_action = NULL;
3212 struct sigaction* os::Linux::get_chained_signal_action(int sig) {
3213 struct sigaction *actp = NULL;
3215 if (libjsig_is_loaded) {
3216 // Retrieve the old signal handler from libjsig
3217 actp = (*get_signal_action)(sig);
3218 }
3219 if (actp == NULL) {
3220 // Retrieve the preinstalled signal handler from jvm
3221 actp = get_preinstalled_handler(sig);
3222 }
3224 return actp;
3225 }
3227 static bool call_chained_handler(struct sigaction *actp, int sig,
3228 siginfo_t *siginfo, void *context) {
3229 // Call the old signal handler
3230 if (actp->sa_handler == SIG_DFL) {
3231 // It's more reasonable to let jvm treat it as an unexpected exception
3232 // instead of taking the default action.
3233 return false;
3234 } else if (actp->sa_handler != SIG_IGN) {
3235 if ((actp->sa_flags & SA_NODEFER) == 0) {
3236 // automaticlly block the signal
3237 sigaddset(&(actp->sa_mask), sig);
3238 }
3240 sa_handler_t hand;
3241 sa_sigaction_t sa;
3242 bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0;
3243 // retrieve the chained handler
3244 if (siginfo_flag_set) {
3245 sa = actp->sa_sigaction;
3246 } else {
3247 hand = actp->sa_handler;
3248 }
3250 if ((actp->sa_flags & SA_RESETHAND) != 0) {
3251 actp->sa_handler = SIG_DFL;
3252 }
3254 // try to honor the signal mask
3255 sigset_t oset;
3256 pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset);
3258 // call into the chained handler
3259 if (siginfo_flag_set) {
3260 (*sa)(sig, siginfo, context);
3261 } else {
3262 (*hand)(sig);
3263 }
3265 // restore the signal mask
3266 pthread_sigmask(SIG_SETMASK, &oset, 0);
3267 }
3268 // Tell jvm's signal handler the signal is taken care of.
3269 return true;
3270 }
3272 bool os::Linux::chained_handler(int sig, siginfo_t* siginfo, void* context) {
3273 bool chained = false;
3274 // signal-chaining
3275 if (UseSignalChaining) {
3276 struct sigaction *actp = get_chained_signal_action(sig);
3277 if (actp != NULL) {
3278 chained = call_chained_handler(actp, sig, siginfo, context);
3279 }
3280 }
3281 return chained;
3282 }
3284 struct sigaction* os::Linux::get_preinstalled_handler(int sig) {
3285 if ((( (unsigned int)1 << sig ) & sigs) != 0) {
3286 return &sigact[sig];
3287 }
3288 return NULL;
3289 }
3291 void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) {
3292 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
3293 sigact[sig] = oldAct;
3294 sigs |= (unsigned int)1 << sig;
3295 }
3297 // for diagnostic
3298 int os::Linux::sigflags[MAXSIGNUM];
3300 int os::Linux::get_our_sigflags(int sig) {
3301 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
3302 return sigflags[sig];
3303 }
3305 void os::Linux::set_our_sigflags(int sig, int flags) {
3306 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
3307 sigflags[sig] = flags;
3308 }
3310 void os::Linux::set_signal_handler(int sig, bool set_installed) {
3311 // Check for overwrite.
3312 struct sigaction oldAct;
3313 sigaction(sig, (struct sigaction*)NULL, &oldAct);
3315 void* oldhand = oldAct.sa_sigaction
3316 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction)
3317 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler);
3318 if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) &&
3319 oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) &&
3320 oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) {
3321 if (AllowUserSignalHandlers || !set_installed) {
3322 // Do not overwrite; user takes responsibility to forward to us.
3323 return;
3324 } else if (UseSignalChaining) {
3325 // save the old handler in jvm
3326 save_preinstalled_handler(sig, oldAct);
3327 // libjsig also interposes the sigaction() call below and saves the
3328 // old sigaction on it own.
3329 } else {
3330 fatal2("Encountered unexpected pre-existing sigaction handler %#lx for signal %d.", (long)oldhand, sig);
3331 }
3332 }
3334 struct sigaction sigAct;
3335 sigfillset(&(sigAct.sa_mask));
3336 sigAct.sa_handler = SIG_DFL;
3337 if (!set_installed) {
3338 sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
3339 } else {
3340 sigAct.sa_sigaction = signalHandler;
3341 sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
3342 }
3343 // Save flags, which are set by ours
3344 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
3345 sigflags[sig] = sigAct.sa_flags;
3347 int ret = sigaction(sig, &sigAct, &oldAct);
3348 assert(ret == 0, "check");
3350 void* oldhand2 = oldAct.sa_sigaction
3351 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction)
3352 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler);
3353 assert(oldhand2 == oldhand, "no concurrent signal handler installation");
3354 }
3356 // install signal handlers for signals that HotSpot needs to
3357 // handle in order to support Java-level exception handling.
3359 void os::Linux::install_signal_handlers() {
3360 if (!signal_handlers_are_installed) {
3361 signal_handlers_are_installed = true;
3363 // signal-chaining
3364 typedef void (*signal_setting_t)();
3365 signal_setting_t begin_signal_setting = NULL;
3366 signal_setting_t end_signal_setting = NULL;
3367 begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
3368 dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting"));
3369 if (begin_signal_setting != NULL) {
3370 end_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
3371 dlsym(RTLD_DEFAULT, "JVM_end_signal_setting"));
3372 get_signal_action = CAST_TO_FN_PTR(get_signal_t,
3373 dlsym(RTLD_DEFAULT, "JVM_get_signal_action"));
3374 libjsig_is_loaded = true;
3375 assert(UseSignalChaining, "should enable signal-chaining");
3376 }
3377 if (libjsig_is_loaded) {
3378 // Tell libjsig jvm is setting signal handlers
3379 (*begin_signal_setting)();
3380 }
3382 set_signal_handler(SIGSEGV, true);
3383 set_signal_handler(SIGPIPE, true);
3384 set_signal_handler(SIGBUS, true);
3385 set_signal_handler(SIGILL, true);
3386 set_signal_handler(SIGFPE, true);
3387 set_signal_handler(SIGXFSZ, true);
3389 if (libjsig_is_loaded) {
3390 // Tell libjsig jvm finishes setting signal handlers
3391 (*end_signal_setting)();
3392 }
3394 // We don't activate signal checker if libjsig is in place, we trust ourselves
3395 // and if UserSignalHandler is installed all bets are off
3396 if (CheckJNICalls) {
3397 if (libjsig_is_loaded) {
3398 tty->print_cr("Info: libjsig is activated, all active signal checking is disabled");
3399 check_signals = false;
3400 }
3401 if (AllowUserSignalHandlers) {
3402 tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled");
3403 check_signals = false;
3404 }
3405 }
3406 }
3407 }
3409 // This is the fastest way to get thread cpu time on Linux.
3410 // Returns cpu time (user+sys) for any thread, not only for current.
3411 // POSIX compliant clocks are implemented in the kernels 2.6.16+.
3412 // It might work on 2.6.10+ with a special kernel/glibc patch.
3413 // For reference, please, see IEEE Std 1003.1-2004:
3414 // http://www.unix.org/single_unix_specification
3416 jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) {
3417 struct timespec tp;
3418 int rc = os::Linux::clock_gettime(clockid, &tp);
3419 assert(rc == 0, "clock_gettime is expected to return 0 code");
3421 return (tp.tv_sec * SEC_IN_NANOSECS) + tp.tv_nsec;
3422 }
3424 /////
3425 // glibc on Linux platform uses non-documented flag
3426 // to indicate, that some special sort of signal
3427 // trampoline is used.
3428 // We will never set this flag, and we should
3429 // ignore this flag in our diagnostic
3430 #ifdef SIGNIFICANT_SIGNAL_MASK
3431 #undef SIGNIFICANT_SIGNAL_MASK
3432 #endif
3433 #define SIGNIFICANT_SIGNAL_MASK (~0x04000000)
3435 static const char* get_signal_handler_name(address handler,
3436 char* buf, int buflen) {
3437 int offset;
3438 bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset);
3439 if (found) {
3440 // skip directory names
3441 const char *p1, *p2;
3442 p1 = buf;
3443 size_t len = strlen(os::file_separator());
3444 while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len;
3445 jio_snprintf(buf, buflen, "%s+0x%x", p1, offset);
3446 } else {
3447 jio_snprintf(buf, buflen, PTR_FORMAT, handler);
3448 }
3449 return buf;
3450 }
3452 static void print_signal_handler(outputStream* st, int sig,
3453 char* buf, size_t buflen) {
3454 struct sigaction sa;
3456 sigaction(sig, NULL, &sa);
3458 // See comment for SIGNIFICANT_SIGNAL_MASK define
3459 sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
3461 st->print("%s: ", os::exception_name(sig, buf, buflen));
3463 address handler = (sa.sa_flags & SA_SIGINFO)
3464 ? CAST_FROM_FN_PTR(address, sa.sa_sigaction)
3465 : CAST_FROM_FN_PTR(address, sa.sa_handler);
3467 if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) {
3468 st->print("SIG_DFL");
3469 } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) {
3470 st->print("SIG_IGN");
3471 } else {
3472 st->print("[%s]", get_signal_handler_name(handler, buf, buflen));
3473 }
3475 st->print(", sa_mask[0]=" PTR32_FORMAT, *(uint32_t*)&sa.sa_mask);
3477 address rh = VMError::get_resetted_sighandler(sig);
3478 // May be, handler was resetted by VMError?
3479 if(rh != NULL) {
3480 handler = rh;
3481 sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK;
3482 }
3484 st->print(", sa_flags=" PTR32_FORMAT, sa.sa_flags);
3486 // Check: is it our handler?
3487 if(handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) ||
3488 handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) {
3489 // It is our signal handler
3490 // check for flags, reset system-used one!
3491 if((int)sa.sa_flags != os::Linux::get_our_sigflags(sig)) {
3492 st->print(
3493 ", flags was changed from " PTR32_FORMAT ", consider using jsig library",
3494 os::Linux::get_our_sigflags(sig));
3495 }
3496 }
3497 st->cr();
3498 }
3501 #define DO_SIGNAL_CHECK(sig) \
3502 if (!sigismember(&check_signal_done, sig)) \
3503 os::Linux::check_signal_handler(sig)
3505 // This method is a periodic task to check for misbehaving JNI applications
3506 // under CheckJNI, we can add any periodic checks here
3508 void os::run_periodic_checks() {
3510 if (check_signals == false) return;
3512 // SEGV and BUS if overridden could potentially prevent
3513 // generation of hs*.log in the event of a crash, debugging
3514 // such a case can be very challenging, so we absolutely
3515 // check the following for a good measure:
3516 DO_SIGNAL_CHECK(SIGSEGV);
3517 DO_SIGNAL_CHECK(SIGILL);
3518 DO_SIGNAL_CHECK(SIGFPE);
3519 DO_SIGNAL_CHECK(SIGBUS);
3520 DO_SIGNAL_CHECK(SIGPIPE);
3521 DO_SIGNAL_CHECK(SIGXFSZ);
3524 // ReduceSignalUsage allows the user to override these handlers
3525 // see comments at the very top and jvm_solaris.h
3526 if (!ReduceSignalUsage) {
3527 DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL);
3528 DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL);
3529 DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL);
3530 DO_SIGNAL_CHECK(BREAK_SIGNAL);
3531 }
3533 DO_SIGNAL_CHECK(SR_signum);
3534 DO_SIGNAL_CHECK(INTERRUPT_SIGNAL);
3535 }
3537 typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *);
3539 static os_sigaction_t os_sigaction = NULL;
3541 void os::Linux::check_signal_handler(int sig) {
3542 char buf[O_BUFLEN];
3543 address jvmHandler = NULL;
3546 struct sigaction act;
3547 if (os_sigaction == NULL) {
3548 // only trust the default sigaction, in case it has been interposed
3549 os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction");
3550 if (os_sigaction == NULL) return;
3551 }
3553 os_sigaction(sig, (struct sigaction*)NULL, &act);
3556 act.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
3558 address thisHandler = (act.sa_flags & SA_SIGINFO)
3559 ? CAST_FROM_FN_PTR(address, act.sa_sigaction)
3560 : CAST_FROM_FN_PTR(address, act.sa_handler) ;
3563 switch(sig) {
3564 case SIGSEGV:
3565 case SIGBUS:
3566 case SIGFPE:
3567 case SIGPIPE:
3568 case SIGILL:
3569 case SIGXFSZ:
3570 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler);
3571 break;
3573 case SHUTDOWN1_SIGNAL:
3574 case SHUTDOWN2_SIGNAL:
3575 case SHUTDOWN3_SIGNAL:
3576 case BREAK_SIGNAL:
3577 jvmHandler = (address)user_handler();
3578 break;
3580 case INTERRUPT_SIGNAL:
3581 jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL);
3582 break;
3584 default:
3585 if (sig == SR_signum) {
3586 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler);
3587 } else {
3588 return;
3589 }
3590 break;
3591 }
3593 if (thisHandler != jvmHandler) {
3594 tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN));
3595 tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN));
3596 tty->print_cr(" found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN));
3597 // No need to check this sig any longer
3598 sigaddset(&check_signal_done, sig);
3599 } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) {
3600 tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN));
3601 tty->print("expected:" PTR32_FORMAT, os::Linux::get_our_sigflags(sig));
3602 tty->print_cr(" found:" PTR32_FORMAT, act.sa_flags);
3603 // No need to check this sig any longer
3604 sigaddset(&check_signal_done, sig);
3605 }
3607 // Dump all the signal
3608 if (sigismember(&check_signal_done, sig)) {
3609 print_signal_handlers(tty, buf, O_BUFLEN);
3610 }
3611 }
3613 extern void report_error(char* file_name, int line_no, char* title, char* format, ...);
3615 extern bool signal_name(int signo, char* buf, size_t len);
3617 const char* os::exception_name(int exception_code, char* buf, size_t size) {
3618 if (0 < exception_code && exception_code <= SIGRTMAX) {
3619 // signal
3620 if (!signal_name(exception_code, buf, size)) {
3621 jio_snprintf(buf, size, "SIG%d", exception_code);
3622 }
3623 return buf;
3624 } else {
3625 return NULL;
3626 }
3627 }
3629 // this is called _before_ the most of global arguments have been parsed
3630 void os::init(void) {
3631 char dummy; /* used to get a guess on initial stack address */
3632 // first_hrtime = gethrtime();
3634 // With LinuxThreads the JavaMain thread pid (primordial thread)
3635 // is different than the pid of the java launcher thread.
3636 // So, on Linux, the launcher thread pid is passed to the VM
3637 // via the sun.java.launcher.pid property.
3638 // Use this property instead of getpid() if it was correctly passed.
3639 // See bug 6351349.
3640 pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid();
3642 _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid();
3644 clock_tics_per_sec = sysconf(_SC_CLK_TCK);
3646 init_random(1234567);
3648 ThreadCritical::initialize();
3650 Linux::set_page_size(sysconf(_SC_PAGESIZE));
3651 if (Linux::page_size() == -1) {
3652 fatal1("os_linux.cpp: os::init: sysconf failed (%s)", strerror(errno));
3653 }
3654 init_page_sizes((size_t) Linux::page_size());
3656 Linux::initialize_system_info();
3658 // main_thread points to the aboriginal thread
3659 Linux::_main_thread = pthread_self();
3661 Linux::clock_init();
3662 initial_time_count = os::elapsed_counter();
3663 pthread_mutex_init(&dl_mutex, NULL);
3664 }
3666 // To install functions for atexit system call
3667 extern "C" {
3668 static void perfMemory_exit_helper() {
3669 perfMemory_exit();
3670 }
3671 }
3673 // this is called _after_ the global arguments have been parsed
3674 jint os::init_2(void)
3675 {
3676 Linux::fast_thread_clock_init();
3678 // Allocate a single page and mark it as readable for safepoint polling
3679 address polling_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
3680 guarantee( polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page" );
3682 os::set_polling_page( polling_page );
3684 #ifndef PRODUCT
3685 if(Verbose && PrintMiscellaneous)
3686 tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n", (intptr_t)polling_page);
3687 #endif
3689 if (!UseMembar) {
3690 address mem_serialize_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
3691 guarantee( mem_serialize_page != NULL, "mmap Failed for memory serialize page");
3692 os::set_memory_serialize_page( mem_serialize_page );
3694 #ifndef PRODUCT
3695 if(Verbose && PrintMiscellaneous)
3696 tty->print("[Memory Serialize Page address: " INTPTR_FORMAT "]\n", (intptr_t)mem_serialize_page);
3697 #endif
3698 }
3700 FLAG_SET_DEFAULT(UseLargePages, os::large_page_init());
3702 // initialize suspend/resume support - must do this before signal_sets_init()
3703 if (SR_initialize() != 0) {
3704 perror("SR_initialize failed");
3705 return JNI_ERR;
3706 }
3708 Linux::signal_sets_init();
3709 Linux::install_signal_handlers();
3711 size_t threadStackSizeInBytes = ThreadStackSize * K;
3712 if (threadStackSizeInBytes != 0 &&
3713 threadStackSizeInBytes < Linux::min_stack_allowed) {
3714 tty->print_cr("\nThe stack size specified is too small, "
3715 "Specify at least %dk",
3716 Linux::min_stack_allowed / K);
3717 return JNI_ERR;
3718 }
3720 // Make the stack size a multiple of the page size so that
3721 // the yellow/red zones can be guarded.
3722 JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes,
3723 vm_page_size()));
3725 Linux::capture_initial_stack(JavaThread::stack_size_at_create());
3727 Linux::libpthread_init();
3728 if (PrintMiscellaneous && (Verbose || WizardMode)) {
3729 tty->print_cr("[HotSpot is running with %s, %s(%s)]\n",
3730 Linux::glibc_version(), Linux::libpthread_version(),
3731 Linux::is_floating_stack() ? "floating stack" : "fixed stack");
3732 }
3734 if (UseNUMA) {
3735 if (!Linux::libnuma_init()) {
3736 UseNUMA = false;
3737 } else {
3738 if ((Linux::numa_max_node() < 1)) {
3739 // There's only one node(they start from 0), disable NUMA.
3740 UseNUMA = false;
3741 }
3742 }
3743 if (!UseNUMA && ForceNUMA) {
3744 UseNUMA = true;
3745 }
3746 }
3748 if (MaxFDLimit) {
3749 // set the number of file descriptors to max. print out error
3750 // if getrlimit/setrlimit fails but continue regardless.
3751 struct rlimit nbr_files;
3752 int status = getrlimit(RLIMIT_NOFILE, &nbr_files);
3753 if (status != 0) {
3754 if (PrintMiscellaneous && (Verbose || WizardMode))
3755 perror("os::init_2 getrlimit failed");
3756 } else {
3757 nbr_files.rlim_cur = nbr_files.rlim_max;
3758 status = setrlimit(RLIMIT_NOFILE, &nbr_files);
3759 if (status != 0) {
3760 if (PrintMiscellaneous && (Verbose || WizardMode))
3761 perror("os::init_2 setrlimit failed");
3762 }
3763 }
3764 }
3766 // Initialize lock used to serialize thread creation (see os::create_thread)
3767 Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false));
3769 // Initialize HPI.
3770 jint hpi_result = hpi::initialize();
3771 if (hpi_result != JNI_OK) {
3772 tty->print_cr("There was an error trying to initialize the HPI library.");
3773 return hpi_result;
3774 }
3776 // at-exit methods are called in the reverse order of their registration.
3777 // atexit functions are called on return from main or as a result of a
3778 // call to exit(3C). There can be only 32 of these functions registered
3779 // and atexit() does not set errno.
3781 if (PerfAllowAtExitRegistration) {
3782 // only register atexit functions if PerfAllowAtExitRegistration is set.
3783 // atexit functions can be delayed until process exit time, which
3784 // can be problematic for embedded VM situations. Embedded VMs should
3785 // call DestroyJavaVM() to assure that VM resources are released.
3787 // note: perfMemory_exit_helper atexit function may be removed in
3788 // the future if the appropriate cleanup code can be added to the
3789 // VM_Exit VMOperation's doit method.
3790 if (atexit(perfMemory_exit_helper) != 0) {
3791 warning("os::init2 atexit(perfMemory_exit_helper) failed");
3792 }
3793 }
3795 // initialize thread priority policy
3796 prio_init();
3798 return JNI_OK;
3799 }
3801 // Mark the polling page as unreadable
3802 void os::make_polling_page_unreadable(void) {
3803 if( !guard_memory((char*)_polling_page, Linux::page_size()) )
3804 fatal("Could not disable polling page");
3805 };
3807 // Mark the polling page as readable
3808 void os::make_polling_page_readable(void) {
3809 if( !linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) {
3810 fatal("Could not enable polling page");
3811 }
3812 };
3814 int os::active_processor_count() {
3815 // Linux doesn't yet have a (official) notion of processor sets,
3816 // so just return the number of online processors.
3817 int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN);
3818 assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check");
3819 return online_cpus;
3820 }
3822 bool os::distribute_processes(uint length, uint* distribution) {
3823 // Not yet implemented.
3824 return false;
3825 }
3827 bool os::bind_to_processor(uint processor_id) {
3828 // Not yet implemented.
3829 return false;
3830 }
3832 ///
3834 // Suspends the target using the signal mechanism and then grabs the PC before
3835 // resuming the target. Used by the flat-profiler only
3836 ExtendedPC os::get_thread_pc(Thread* thread) {
3837 // Make sure that it is called by the watcher for the VMThread
3838 assert(Thread::current()->is_Watcher_thread(), "Must be watcher");
3839 assert(thread->is_VM_thread(), "Can only be called for VMThread");
3841 ExtendedPC epc;
3843 OSThread* osthread = thread->osthread();
3844 if (do_suspend(osthread)) {
3845 if (osthread->ucontext() != NULL) {
3846 epc = os::Linux::ucontext_get_pc(osthread->ucontext());
3847 } else {
3848 // NULL context is unexpected, double-check this is the VMThread
3849 guarantee(thread->is_VM_thread(), "can only be called for VMThread");
3850 }
3851 do_resume(osthread);
3852 }
3853 // failure means pthread_kill failed for some reason - arguably this is
3854 // a fatal problem, but such problems are ignored elsewhere
3856 return epc;
3857 }
3859 int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond, pthread_mutex_t *_mutex, const struct timespec *_abstime)
3860 {
3861 if (is_NPTL()) {
3862 return pthread_cond_timedwait(_cond, _mutex, _abstime);
3863 } else {
3864 #ifndef IA64
3865 // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control
3866 // word back to default 64bit precision if condvar is signaled. Java
3867 // wants 53bit precision. Save and restore current value.
3868 int fpu = get_fpu_control_word();
3869 #endif // IA64
3870 int status = pthread_cond_timedwait(_cond, _mutex, _abstime);
3871 #ifndef IA64
3872 set_fpu_control_word(fpu);
3873 #endif // IA64
3874 return status;
3875 }
3876 }
3878 ////////////////////////////////////////////////////////////////////////////////
3879 // debug support
3881 #ifndef PRODUCT
3882 static address same_page(address x, address y) {
3883 int page_bits = -os::vm_page_size();
3884 if ((intptr_t(x) & page_bits) == (intptr_t(y) & page_bits))
3885 return x;
3886 else if (x > y)
3887 return (address)(intptr_t(y) | ~page_bits) + 1;
3888 else
3889 return (address)(intptr_t(y) & page_bits);
3890 }
3892 bool os::find(address addr) {
3893 Dl_info dlinfo;
3894 memset(&dlinfo, 0, sizeof(dlinfo));
3895 if (dladdr(addr, &dlinfo)) {
3896 tty->print(PTR_FORMAT ": ", addr);
3897 if (dlinfo.dli_sname != NULL) {
3898 tty->print("%s+%#x", dlinfo.dli_sname,
3899 addr - (intptr_t)dlinfo.dli_saddr);
3900 } else if (dlinfo.dli_fname) {
3901 tty->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase);
3902 } else {
3903 tty->print("<absolute address>");
3904 }
3905 if (dlinfo.dli_fname) {
3906 tty->print(" in %s", dlinfo.dli_fname);
3907 }
3908 if (dlinfo.dli_fbase) {
3909 tty->print(" at " PTR_FORMAT, dlinfo.dli_fbase);
3910 }
3911 tty->cr();
3913 if (Verbose) {
3914 // decode some bytes around the PC
3915 address begin = same_page(addr-40, addr);
3916 address end = same_page(addr+40, addr);
3917 address lowest = (address) dlinfo.dli_sname;
3918 if (!lowest) lowest = (address) dlinfo.dli_fbase;
3919 if (begin < lowest) begin = lowest;
3920 Dl_info dlinfo2;
3921 if (dladdr(end, &dlinfo2) && dlinfo2.dli_saddr != dlinfo.dli_saddr
3922 && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin)
3923 end = (address) dlinfo2.dli_saddr;
3924 Disassembler::decode(begin, end);
3925 }
3926 return true;
3927 }
3928 return false;
3929 }
3931 #endif
3933 ////////////////////////////////////////////////////////////////////////////////
3934 // misc
3936 // This does not do anything on Linux. This is basically a hook for being
3937 // able to use structured exception handling (thread-local exception filters)
3938 // on, e.g., Win32.
3939 void
3940 os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method,
3941 JavaCallArguments* args, Thread* thread) {
3942 f(value, method, args, thread);
3943 }
3945 void os::print_statistics() {
3946 }
3948 int os::message_box(const char* title, const char* message) {
3949 int i;
3950 fdStream err(defaultStream::error_fd());
3951 for (i = 0; i < 78; i++) err.print_raw("=");
3952 err.cr();
3953 err.print_raw_cr(title);
3954 for (i = 0; i < 78; i++) err.print_raw("-");
3955 err.cr();
3956 err.print_raw_cr(message);
3957 for (i = 0; i < 78; i++) err.print_raw("=");
3958 err.cr();
3960 char buf[16];
3961 // Prevent process from exiting upon "read error" without consuming all CPU
3962 while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); }
3964 return buf[0] == 'y' || buf[0] == 'Y';
3965 }
3967 int os::stat(const char *path, struct stat *sbuf) {
3968 char pathbuf[MAX_PATH];
3969 if (strlen(path) > MAX_PATH - 1) {
3970 errno = ENAMETOOLONG;
3971 return -1;
3972 }
3973 hpi::native_path(strcpy(pathbuf, path));
3974 return ::stat(pathbuf, sbuf);
3975 }
3977 bool os::check_heap(bool force) {
3978 return true;
3979 }
3981 int local_vsnprintf(char* buf, size_t count, const char* format, va_list args) {
3982 return ::vsnprintf(buf, count, format, args);
3983 }
3985 // Is a (classpath) directory empty?
3986 bool os::dir_is_empty(const char* path) {
3987 DIR *dir = NULL;
3988 struct dirent *ptr;
3990 dir = opendir(path);
3991 if (dir == NULL) return true;
3993 /* Scan the directory */
3994 bool result = true;
3995 char buf[sizeof(struct dirent) + MAX_PATH];
3996 while (result && (ptr = ::readdir(dir)) != NULL) {
3997 if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) {
3998 result = false;
3999 }
4000 }
4001 closedir(dir);
4002 return result;
4003 }
4005 // create binary file, rewriting existing file if required
4006 int os::create_binary_file(const char* path, bool rewrite_existing) {
4007 int oflags = O_WRONLY | O_CREAT;
4008 if (!rewrite_existing) {
4009 oflags |= O_EXCL;
4010 }
4011 return ::open64(path, oflags, S_IREAD | S_IWRITE);
4012 }
4014 // return current position of file pointer
4015 jlong os::current_file_offset(int fd) {
4016 return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR);
4017 }
4019 // move file pointer to the specified offset
4020 jlong os::seek_to_file_offset(int fd, jlong offset) {
4021 return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET);
4022 }
4024 // Map a block of memory.
4025 char* os::map_memory(int fd, const char* file_name, size_t file_offset,
4026 char *addr, size_t bytes, bool read_only,
4027 bool allow_exec) {
4028 int prot;
4029 int flags;
4031 if (read_only) {
4032 prot = PROT_READ;
4033 flags = MAP_SHARED;
4034 } else {
4035 prot = PROT_READ | PROT_WRITE;
4036 flags = MAP_PRIVATE;
4037 }
4039 if (allow_exec) {
4040 prot |= PROT_EXEC;
4041 }
4043 if (addr != NULL) {
4044 flags |= MAP_FIXED;
4045 }
4047 char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags,
4048 fd, file_offset);
4049 if (mapped_address == MAP_FAILED) {
4050 return NULL;
4051 }
4052 return mapped_address;
4053 }
4056 // Remap a block of memory.
4057 char* os::remap_memory(int fd, const char* file_name, size_t file_offset,
4058 char *addr, size_t bytes, bool read_only,
4059 bool allow_exec) {
4060 // same as map_memory() on this OS
4061 return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only,
4062 allow_exec);
4063 }
4066 // Unmap a block of memory.
4067 bool os::unmap_memory(char* addr, size_t bytes) {
4068 return munmap(addr, bytes) == 0;
4069 }
4071 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time);
4073 static clockid_t thread_cpu_clockid(Thread* thread) {
4074 pthread_t tid = thread->osthread()->pthread_id();
4075 clockid_t clockid;
4077 // Get thread clockid
4078 int rc = os::Linux::pthread_getcpuclockid(tid, &clockid);
4079 assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code");
4080 return clockid;
4081 }
4083 // current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool)
4084 // are used by JVM M&M and JVMTI to get user+sys or user CPU time
4085 // of a thread.
4086 //
4087 // current_thread_cpu_time() and thread_cpu_time(Thread*) returns
4088 // the fast estimate available on the platform.
4090 jlong os::current_thread_cpu_time() {
4091 if (os::Linux::supports_fast_thread_cpu_time()) {
4092 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
4093 } else {
4094 // return user + sys since the cost is the same
4095 return slow_thread_cpu_time(Thread::current(), true /* user + sys */);
4096 }
4097 }
4099 jlong os::thread_cpu_time(Thread* thread) {
4100 // consistent with what current_thread_cpu_time() returns
4101 if (os::Linux::supports_fast_thread_cpu_time()) {
4102 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread));
4103 } else {
4104 return slow_thread_cpu_time(thread, true /* user + sys */);
4105 }
4106 }
4108 jlong os::current_thread_cpu_time(bool user_sys_cpu_time) {
4109 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
4110 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
4111 } else {
4112 return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time);
4113 }
4114 }
4116 jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
4117 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
4118 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread));
4119 } else {
4120 return slow_thread_cpu_time(thread, user_sys_cpu_time);
4121 }
4122 }
4124 //
4125 // -1 on error.
4126 //
4128 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
4129 static bool proc_pid_cpu_avail = true;
4130 static bool proc_task_unchecked = true;
4131 static const char *proc_stat_path = "/proc/%d/stat";
4132 pid_t tid = thread->osthread()->thread_id();
4133 int i;
4134 char *s;
4135 char stat[2048];
4136 int statlen;
4137 char proc_name[64];
4138 int count;
4139 long sys_time, user_time;
4140 char string[64];
4141 int idummy;
4142 long ldummy;
4143 FILE *fp;
4145 // We first try accessing /proc/<pid>/cpu since this is faster to
4146 // process. If this file is not present (linux kernels 2.5 and above)
4147 // then we open /proc/<pid>/stat.
4148 if ( proc_pid_cpu_avail ) {
4149 sprintf(proc_name, "/proc/%d/cpu", tid);
4150 fp = fopen(proc_name, "r");
4151 if ( fp != NULL ) {
4152 count = fscanf( fp, "%s %lu %lu\n", string, &user_time, &sys_time);
4153 fclose(fp);
4154 if ( count != 3 ) return -1;
4156 if (user_sys_cpu_time) {
4157 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec);
4158 } else {
4159 return (jlong)user_time * (1000000000 / clock_tics_per_sec);
4160 }
4161 }
4162 else proc_pid_cpu_avail = false;
4163 }
4165 // The /proc/<tid>/stat aggregates per-process usage on
4166 // new Linux kernels 2.6+ where NPTL is supported.
4167 // The /proc/self/task/<tid>/stat still has the per-thread usage.
4168 // See bug 6328462.
4169 // There can be no directory /proc/self/task on kernels 2.4 with NPTL
4170 // and possibly in some other cases, so we check its availability.
4171 if (proc_task_unchecked && os::Linux::is_NPTL()) {
4172 // This is executed only once
4173 proc_task_unchecked = false;
4174 fp = fopen("/proc/self/task", "r");
4175 if (fp != NULL) {
4176 proc_stat_path = "/proc/self/task/%d/stat";
4177 fclose(fp);
4178 }
4179 }
4181 sprintf(proc_name, proc_stat_path, tid);
4182 fp = fopen(proc_name, "r");
4183 if ( fp == NULL ) return -1;
4184 statlen = fread(stat, 1, 2047, fp);
4185 stat[statlen] = '\0';
4186 fclose(fp);
4188 // Skip pid and the command string. Note that we could be dealing with
4189 // weird command names, e.g. user could decide to rename java launcher
4190 // to "java 1.4.2 :)", then the stat file would look like
4191 // 1234 (java 1.4.2 :)) R ... ...
4192 // We don't really need to know the command string, just find the last
4193 // occurrence of ")" and then start parsing from there. See bug 4726580.
4194 s = strrchr(stat, ')');
4195 i = 0;
4196 if (s == NULL ) return -1;
4198 // Skip blank chars
4199 do s++; while (isspace(*s));
4201 count = sscanf(s,"%*c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu",
4202 &idummy, &idummy, &idummy, &idummy, &idummy,
4203 &ldummy, &ldummy, &ldummy, &ldummy, &ldummy,
4204 &user_time, &sys_time);
4205 if ( count != 12 ) return -1;
4206 if (user_sys_cpu_time) {
4207 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec);
4208 } else {
4209 return (jlong)user_time * (1000000000 / clock_tics_per_sec);
4210 }
4211 }
4213 void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
4214 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits
4215 info_ptr->may_skip_backward = false; // elapsed time not wall time
4216 info_ptr->may_skip_forward = false; // elapsed time not wall time
4217 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned
4218 }
4220 void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
4221 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits
4222 info_ptr->may_skip_backward = false; // elapsed time not wall time
4223 info_ptr->may_skip_forward = false; // elapsed time not wall time
4224 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned
4225 }
4227 bool os::is_thread_cpu_time_supported() {
4228 return true;
4229 }
4231 // System loadavg support. Returns -1 if load average cannot be obtained.
4232 // Linux doesn't yet have a (official) notion of processor sets,
4233 // so just return the system wide load average.
4234 int os::loadavg(double loadavg[], int nelem) {
4235 return ::getloadavg(loadavg, nelem);
4236 }
4238 void os::pause() {
4239 char filename[MAX_PATH];
4240 if (PauseAtStartupFile && PauseAtStartupFile[0]) {
4241 jio_snprintf(filename, MAX_PATH, PauseAtStartupFile);
4242 } else {
4243 jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id());
4244 }
4246 int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
4247 if (fd != -1) {
4248 struct stat buf;
4249 close(fd);
4250 while (::stat(filename, &buf) == 0) {
4251 (void)::poll(NULL, 0, 100);
4252 }
4253 } else {
4254 jio_fprintf(stderr,
4255 "Could not open pause file '%s', continuing immediately.\n", filename);
4256 }
4257 }
4259 extern "C" {
4261 /**
4262 * NOTE: the following code is to keep the green threads code
4263 * in the libjava.so happy. Once the green threads is removed,
4264 * these code will no longer be needed.
4265 */
4266 int
4267 jdk_waitpid(pid_t pid, int* status, int options) {
4268 return waitpid(pid, status, options);
4269 }
4271 int
4272 fork1() {
4273 return fork();
4274 }
4276 int
4277 jdk_sem_init(sem_t *sem, int pshared, unsigned int value) {
4278 return sem_init(sem, pshared, value);
4279 }
4281 int
4282 jdk_sem_post(sem_t *sem) {
4283 return sem_post(sem);
4284 }
4286 int
4287 jdk_sem_wait(sem_t *sem) {
4288 return sem_wait(sem);
4289 }
4291 int
4292 jdk_pthread_sigmask(int how , const sigset_t* newmask, sigset_t* oldmask) {
4293 return pthread_sigmask(how , newmask, oldmask);
4294 }
4296 }
4298 // Refer to the comments in os_solaris.cpp park-unpark.
4299 //
4300 // Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can
4301 // hang indefinitely. For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable.
4302 // For specifics regarding the bug see GLIBC BUGID 261237 :
4303 // http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html.
4304 // Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future
4305 // will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar
4306 // is used. (The simple C test-case provided in the GLIBC bug report manifests the
4307 // hang). The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos()
4308 // and monitorenter when we're using 1-0 locking. All those operations may result in
4309 // calls to pthread_cond_timedwait(). Using LD_ASSUME_KERNEL to use an older version
4310 // of libpthread avoids the problem, but isn't practical.
4311 //
4312 // Possible remedies:
4313 //
4314 // 1. Establish a minimum relative wait time. 50 to 100 msecs seems to work.
4315 // This is palliative and probabilistic, however. If the thread is preempted
4316 // between the call to compute_abstime() and pthread_cond_timedwait(), more
4317 // than the minimum period may have passed, and the abstime may be stale (in the
4318 // past) resultin in a hang. Using this technique reduces the odds of a hang
4319 // but the JVM is still vulnerable, particularly on heavily loaded systems.
4320 //
4321 // 2. Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead
4322 // of the usual flag-condvar-mutex idiom. The write side of the pipe is set
4323 // NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo)
4324 // reduces to poll()+read(). This works well, but consumes 2 FDs per extant
4325 // thread.
4326 //
4327 // 3. Embargo pthread_cond_timedwait() and implement a native "chron" thread
4328 // that manages timeouts. We'd emulate pthread_cond_timedwait() by enqueuing
4329 // a timeout request to the chron thread and then blocking via pthread_cond_wait().
4330 // This also works well. In fact it avoids kernel-level scalability impediments
4331 // on certain platforms that don't handle lots of active pthread_cond_timedwait()
4332 // timers in a graceful fashion.
4333 //
4334 // 4. When the abstime value is in the past it appears that control returns
4335 // correctly from pthread_cond_timedwait(), but the condvar is left corrupt.
4336 // Subsequent timedwait/wait calls may hang indefinitely. Given that, we
4337 // can avoid the problem by reinitializing the condvar -- by cond_destroy()
4338 // followed by cond_init() -- after all calls to pthread_cond_timedwait().
4339 // It may be possible to avoid reinitialization by checking the return
4340 // value from pthread_cond_timedwait(). In addition to reinitializing the
4341 // condvar we must establish the invariant that cond_signal() is only called
4342 // within critical sections protected by the adjunct mutex. This prevents
4343 // cond_signal() from "seeing" a condvar that's in the midst of being
4344 // reinitialized or that is corrupt. Sadly, this invariant obviates the
4345 // desirable signal-after-unlock optimization that avoids futile context switching.
4346 //
4347 // I'm also concerned that some versions of NTPL might allocate an auxilliary
4348 // structure when a condvar is used or initialized. cond_destroy() would
4349 // release the helper structure. Our reinitialize-after-timedwait fix
4350 // put excessive stress on malloc/free and locks protecting the c-heap.
4351 //
4352 // We currently use (4). See the WorkAroundNTPLTimedWaitHang flag.
4353 // It may be possible to refine (4) by checking the kernel and NTPL verisons
4354 // and only enabling the work-around for vulnerable environments.
4356 // utility to compute the abstime argument to timedwait:
4357 // millis is the relative timeout time
4358 // abstime will be the absolute timeout time
4359 // TODO: replace compute_abstime() with unpackTime()
4361 static struct timespec* compute_abstime(timespec* abstime, jlong millis) {
4362 if (millis < 0) millis = 0;
4363 struct timeval now;
4364 int status = gettimeofday(&now, NULL);
4365 assert(status == 0, "gettimeofday");
4366 jlong seconds = millis / 1000;
4367 millis %= 1000;
4368 if (seconds > 50000000) { // see man cond_timedwait(3T)
4369 seconds = 50000000;
4370 }
4371 abstime->tv_sec = now.tv_sec + seconds;
4372 long usec = now.tv_usec + millis * 1000;
4373 if (usec >= 1000000) {
4374 abstime->tv_sec += 1;
4375 usec -= 1000000;
4376 }
4377 abstime->tv_nsec = usec * 1000;
4378 return abstime;
4379 }
4382 // Test-and-clear _Event, always leaves _Event set to 0, returns immediately.
4383 // Conceptually TryPark() should be equivalent to park(0).
4385 int os::PlatformEvent::TryPark() {
4386 for (;;) {
4387 const int v = _Event ;
4388 guarantee ((v == 0) || (v == 1), "invariant") ;
4389 if (Atomic::cmpxchg (0, &_Event, v) == v) return v ;
4390 }
4391 }
4393 void os::PlatformEvent::park() { // AKA "down()"
4394 // Invariant: Only the thread associated with the Event/PlatformEvent
4395 // may call park().
4396 // TODO: assert that _Assoc != NULL or _Assoc == Self
4397 int v ;
4398 for (;;) {
4399 v = _Event ;
4400 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ;
4401 }
4402 guarantee (v >= 0, "invariant") ;
4403 if (v == 0) {
4404 // Do this the hard way by blocking ...
4405 int status = pthread_mutex_lock(_mutex);
4406 assert_status(status == 0, status, "mutex_lock");
4407 guarantee (_nParked == 0, "invariant") ;
4408 ++ _nParked ;
4409 while (_Event < 0) {
4410 status = pthread_cond_wait(_cond, _mutex);
4411 // for some reason, under 2.7 lwp_cond_wait() may return ETIME ...
4412 // Treat this the same as if the wait was interrupted
4413 if (status == ETIME) { status = EINTR; }
4414 assert_status(status == 0 || status == EINTR, status, "cond_wait");
4415 }
4416 -- _nParked ;
4418 // In theory we could move the ST of 0 into _Event past the unlock(),
4419 // but then we'd need a MEMBAR after the ST.
4420 _Event = 0 ;
4421 status = pthread_mutex_unlock(_mutex);
4422 assert_status(status == 0, status, "mutex_unlock");
4423 }
4424 guarantee (_Event >= 0, "invariant") ;
4425 }
4427 int os::PlatformEvent::park(jlong millis) {
4428 guarantee (_nParked == 0, "invariant") ;
4430 int v ;
4431 for (;;) {
4432 v = _Event ;
4433 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ;
4434 }
4435 guarantee (v >= 0, "invariant") ;
4436 if (v != 0) return OS_OK ;
4438 // We do this the hard way, by blocking the thread.
4439 // Consider enforcing a minimum timeout value.
4440 struct timespec abst;
4441 compute_abstime(&abst, millis);
4443 int ret = OS_TIMEOUT;
4444 int status = pthread_mutex_lock(_mutex);
4445 assert_status(status == 0, status, "mutex_lock");
4446 guarantee (_nParked == 0, "invariant") ;
4447 ++_nParked ;
4449 // Object.wait(timo) will return because of
4450 // (a) notification
4451 // (b) timeout
4452 // (c) thread.interrupt
4453 //
4454 // Thread.interrupt and object.notify{All} both call Event::set.
4455 // That is, we treat thread.interrupt as a special case of notification.
4456 // The underlying Solaris implementation, cond_timedwait, admits
4457 // spurious/premature wakeups, but the JLS/JVM spec prevents the
4458 // JVM from making those visible to Java code. As such, we must
4459 // filter out spurious wakeups. We assume all ETIME returns are valid.
4460 //
4461 // TODO: properly differentiate simultaneous notify+interrupt.
4462 // In that case, we should propagate the notify to another waiter.
4464 while (_Event < 0) {
4465 status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst);
4466 if (status != 0 && WorkAroundNPTLTimedWaitHang) {
4467 pthread_cond_destroy (_cond);
4468 pthread_cond_init (_cond, NULL) ;
4469 }
4470 assert_status(status == 0 || status == EINTR ||
4471 status == ETIME || status == ETIMEDOUT,
4472 status, "cond_timedwait");
4473 if (!FilterSpuriousWakeups) break ; // previous semantics
4474 if (status == ETIME || status == ETIMEDOUT) break ;
4475 // We consume and ignore EINTR and spurious wakeups.
4476 }
4477 --_nParked ;
4478 if (_Event >= 0) {
4479 ret = OS_OK;
4480 }
4481 _Event = 0 ;
4482 status = pthread_mutex_unlock(_mutex);
4483 assert_status(status == 0, status, "mutex_unlock");
4484 assert (_nParked == 0, "invariant") ;
4485 return ret;
4486 }
4488 void os::PlatformEvent::unpark() {
4489 int v, AnyWaiters ;
4490 for (;;) {
4491 v = _Event ;
4492 if (v > 0) {
4493 // The LD of _Event could have reordered or be satisfied
4494 // by a read-aside from this processor's write buffer.
4495 // To avoid problems execute a barrier and then
4496 // ratify the value.
4497 OrderAccess::fence() ;
4498 if (_Event == v) return ;
4499 continue ;
4500 }
4501 if (Atomic::cmpxchg (v+1, &_Event, v) == v) break ;
4502 }
4503 if (v < 0) {
4504 // Wait for the thread associated with the event to vacate
4505 int status = pthread_mutex_lock(_mutex);
4506 assert_status(status == 0, status, "mutex_lock");
4507 AnyWaiters = _nParked ;
4508 assert (AnyWaiters == 0 || AnyWaiters == 1, "invariant") ;
4509 if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) {
4510 AnyWaiters = 0 ;
4511 pthread_cond_signal (_cond);
4512 }
4513 status = pthread_mutex_unlock(_mutex);
4514 assert_status(status == 0, status, "mutex_unlock");
4515 if (AnyWaiters != 0) {
4516 status = pthread_cond_signal(_cond);
4517 assert_status(status == 0, status, "cond_signal");
4518 }
4519 }
4521 // Note that we signal() _after dropping the lock for "immortal" Events.
4522 // This is safe and avoids a common class of futile wakeups. In rare
4523 // circumstances this can cause a thread to return prematurely from
4524 // cond_{timed}wait() but the spurious wakeup is benign and the victim will
4525 // simply re-test the condition and re-park itself.
4526 }
4529 // JSR166
4530 // -------------------------------------------------------
4532 /*
4533 * The solaris and linux implementations of park/unpark are fairly
4534 * conservative for now, but can be improved. They currently use a
4535 * mutex/condvar pair, plus a a count.
4536 * Park decrements count if > 0, else does a condvar wait. Unpark
4537 * sets count to 1 and signals condvar. Only one thread ever waits
4538 * on the condvar. Contention seen when trying to park implies that someone
4539 * is unparking you, so don't wait. And spurious returns are fine, so there
4540 * is no need to track notifications.
4541 */
4544 #define NANOSECS_PER_SEC 1000000000
4545 #define NANOSECS_PER_MILLISEC 1000000
4546 #define MAX_SECS 100000000
4547 /*
4548 * This code is common to linux and solaris and will be moved to a
4549 * common place in dolphin.
4550 *
4551 * The passed in time value is either a relative time in nanoseconds
4552 * or an absolute time in milliseconds. Either way it has to be unpacked
4553 * into suitable seconds and nanoseconds components and stored in the
4554 * given timespec structure.
4555 * Given time is a 64-bit value and the time_t used in the timespec is only
4556 * a signed-32-bit value (except on 64-bit Linux) we have to watch for
4557 * overflow if times way in the future are given. Further on Solaris versions
4558 * prior to 10 there is a restriction (see cond_timedwait) that the specified
4559 * number of seconds, in abstime, is less than current_time + 100,000,000.
4560 * As it will be 28 years before "now + 100000000" will overflow we can
4561 * ignore overflow and just impose a hard-limit on seconds using the value
4562 * of "now + 100,000,000". This places a limit on the timeout of about 3.17
4563 * years from "now".
4564 */
4566 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) {
4567 assert (time > 0, "convertTime");
4569 struct timeval now;
4570 int status = gettimeofday(&now, NULL);
4571 assert(status == 0, "gettimeofday");
4573 time_t max_secs = now.tv_sec + MAX_SECS;
4575 if (isAbsolute) {
4576 jlong secs = time / 1000;
4577 if (secs > max_secs) {
4578 absTime->tv_sec = max_secs;
4579 }
4580 else {
4581 absTime->tv_sec = secs;
4582 }
4583 absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC;
4584 }
4585 else {
4586 jlong secs = time / NANOSECS_PER_SEC;
4587 if (secs >= MAX_SECS) {
4588 absTime->tv_sec = max_secs;
4589 absTime->tv_nsec = 0;
4590 }
4591 else {
4592 absTime->tv_sec = now.tv_sec + secs;
4593 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000;
4594 if (absTime->tv_nsec >= NANOSECS_PER_SEC) {
4595 absTime->tv_nsec -= NANOSECS_PER_SEC;
4596 ++absTime->tv_sec; // note: this must be <= max_secs
4597 }
4598 }
4599 }
4600 assert(absTime->tv_sec >= 0, "tv_sec < 0");
4601 assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs");
4602 assert(absTime->tv_nsec >= 0, "tv_nsec < 0");
4603 assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec");
4604 }
4606 void Parker::park(bool isAbsolute, jlong time) {
4607 // Optional fast-path check:
4608 // Return immediately if a permit is available.
4609 if (_counter > 0) {
4610 _counter = 0 ;
4611 return ;
4612 }
4614 Thread* thread = Thread::current();
4615 assert(thread->is_Java_thread(), "Must be JavaThread");
4616 JavaThread *jt = (JavaThread *)thread;
4618 // Optional optimization -- avoid state transitions if there's an interrupt pending.
4619 // Check interrupt before trying to wait
4620 if (Thread::is_interrupted(thread, false)) {
4621 return;
4622 }
4624 // Next, demultiplex/decode time arguments
4625 timespec absTime;
4626 if (time < 0) { // don't wait at all
4627 return;
4628 }
4629 if (time > 0) {
4630 unpackTime(&absTime, isAbsolute, time);
4631 }
4634 // Enter safepoint region
4635 // Beware of deadlocks such as 6317397.
4636 // The per-thread Parker:: mutex is a classic leaf-lock.
4637 // In particular a thread must never block on the Threads_lock while
4638 // holding the Parker:: mutex. If safepoints are pending both the
4639 // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock.
4640 ThreadBlockInVM tbivm(jt);
4642 // Don't wait if cannot get lock since interference arises from
4643 // unblocking. Also. check interrupt before trying wait
4644 if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) {
4645 return;
4646 }
4648 int status ;
4649 if (_counter > 0) { // no wait needed
4650 _counter = 0;
4651 status = pthread_mutex_unlock(_mutex);
4652 assert (status == 0, "invariant") ;
4653 return;
4654 }
4656 #ifdef ASSERT
4657 // Don't catch signals while blocked; let the running threads have the signals.
4658 // (This allows a debugger to break into the running thread.)
4659 sigset_t oldsigs;
4660 sigset_t* allowdebug_blocked = os::Linux::allowdebug_blocked_signals();
4661 pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs);
4662 #endif
4664 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */);
4665 jt->set_suspend_equivalent();
4666 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
4668 if (time == 0) {
4669 status = pthread_cond_wait (_cond, _mutex) ;
4670 } else {
4671 status = os::Linux::safe_cond_timedwait (_cond, _mutex, &absTime) ;
4672 if (status != 0 && WorkAroundNPTLTimedWaitHang) {
4673 pthread_cond_destroy (_cond) ;
4674 pthread_cond_init (_cond, NULL);
4675 }
4676 }
4677 assert_status(status == 0 || status == EINTR ||
4678 status == ETIME || status == ETIMEDOUT,
4679 status, "cond_timedwait");
4681 #ifdef ASSERT
4682 pthread_sigmask(SIG_SETMASK, &oldsigs, NULL);
4683 #endif
4685 _counter = 0 ;
4686 status = pthread_mutex_unlock(_mutex) ;
4687 assert_status(status == 0, status, "invariant") ;
4688 // If externally suspended while waiting, re-suspend
4689 if (jt->handle_special_suspend_equivalent_condition()) {
4690 jt->java_suspend_self();
4691 }
4693 }
4695 void Parker::unpark() {
4696 int s, status ;
4697 status = pthread_mutex_lock(_mutex);
4698 assert (status == 0, "invariant") ;
4699 s = _counter;
4700 _counter = 1;
4701 if (s < 1) {
4702 if (WorkAroundNPTLTimedWaitHang) {
4703 status = pthread_cond_signal (_cond) ;
4704 assert (status == 0, "invariant") ;
4705 status = pthread_mutex_unlock(_mutex);
4706 assert (status == 0, "invariant") ;
4707 } else {
4708 status = pthread_mutex_unlock(_mutex);
4709 assert (status == 0, "invariant") ;
4710 status = pthread_cond_signal (_cond) ;
4711 assert (status == 0, "invariant") ;
4712 }
4713 } else {
4714 pthread_mutex_unlock(_mutex);
4715 assert (status == 0, "invariant") ;
4716 }
4717 }
4720 extern char** environ;
4722 #ifndef __NR_fork
4723 #define __NR_fork IA32_ONLY(2) IA64_ONLY(not defined) AMD64_ONLY(57)
4724 #endif
4726 #ifndef __NR_execve
4727 #define __NR_execve IA32_ONLY(11) IA64_ONLY(1033) AMD64_ONLY(59)
4728 #endif
4730 // Run the specified command in a separate process. Return its exit value,
4731 // or -1 on failure (e.g. can't fork a new process).
4732 // Unlike system(), this function can be called from signal handler. It
4733 // doesn't block SIGINT et al.
4734 int os::fork_and_exec(char* cmd) {
4735 const char * argv[4] = {"sh", "-c", cmd, NULL};
4737 // fork() in LinuxThreads/NPTL is not async-safe. It needs to run
4738 // pthread_atfork handlers and reset pthread library. All we need is a
4739 // separate process to execve. Make a direct syscall to fork process.
4740 // On IA64 there's no fork syscall, we have to use fork() and hope for
4741 // the best...
4742 pid_t pid = NOT_IA64(syscall(__NR_fork);)
4743 IA64_ONLY(fork();)
4745 if (pid < 0) {
4746 // fork failed
4747 return -1;
4749 } else if (pid == 0) {
4750 // child process
4752 // execve() in LinuxThreads will call pthread_kill_other_threads_np()
4753 // first to kill every thread on the thread list. Because this list is
4754 // not reset by fork() (see notes above), execve() will instead kill
4755 // every thread in the parent process. We know this is the only thread
4756 // in the new process, so make a system call directly.
4757 // IA64 should use normal execve() from glibc to match the glibc fork()
4758 // above.
4759 NOT_IA64(syscall(__NR_execve, "/bin/sh", argv, environ);)
4760 IA64_ONLY(execve("/bin/sh", (char* const*)argv, environ);)
4762 // execve failed
4763 _exit(-1);
4765 } else {
4766 // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't
4767 // care about the actual exit code, for now.
4769 int status;
4771 // Wait for the child process to exit. This returns immediately if
4772 // the child has already exited. */
4773 while (waitpid(pid, &status, 0) < 0) {
4774 switch (errno) {
4775 case ECHILD: return 0;
4776 case EINTR: break;
4777 default: return -1;
4778 }
4779 }
4781 if (WIFEXITED(status)) {
4782 // The child exited normally; get its exit code.
4783 return WEXITSTATUS(status);
4784 } else if (WIFSIGNALED(status)) {
4785 // The child exited because of a signal
4786 // The best value to return is 0x80 + signal number,
4787 // because that is what all Unix shells do, and because
4788 // it allows callers to distinguish between process exit and
4789 // process death by signal.
4790 return 0x80 + WTERMSIG(status);
4791 } else {
4792 // Unknown exit code; pass it through
4793 return status;
4794 }
4795 }
4796 }