1 /*
2 * Copyright 1999-2009 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 */
24
25 // do not include precompiled header file
26 # include "incls/_os_linux.cpp.incl"
27
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>
56
57 #define MAX_PATH (2 * K)
58
59 // for timer info max values which include all bits
60 #define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF)
61 #define SEC_IN_NANOSECS 1000000000LL
62
63 ////////////////////////////////////////////////////////////////////////////////
64 // global variables
65 julong os::Linux::_physical_memory = 0;
66
67 address os::Linux::_initial_thread_stack_bottom = NULL;
68 uintptr_t os::Linux::_initial_thread_stack_size = 0;
69
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;
80
81 static jlong initial_time_count=0;
82
83 static int clock_tics_per_sec = 100;
84
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;;
88
89 static pid_t _initial_pid = 0;
90
91 /* Signal number used to suspend/resume a thread */
92
93 /* do not use any signal number less than SIGSEGV, see 4355769 */
94 static int SR_signum = SIGUSR2;
95 sigset_t SR_sigset;
96
97 /* Used to protect dlsym() calls */
98 static pthread_mutex_t dl_mutex;
99
100 ////////////////////////////////////////////////////////////////////////////////
101 // utility functions
102
103 static int SR_initialize();
104 static int SR_finalize();
105
106 julong os::available_memory() {
107 return Linux::available_memory();
108 }
109
110 julong os::Linux::available_memory() {
111 // values in struct sysinfo are "unsigned long"
112 struct sysinfo si;
113 sysinfo(&si);
114
115 return (julong)si.freeram * si.mem_unit;
116 }
117
118 julong os::physical_memory() {
119 return Linux::physical_memory();
120 }
121
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 }
135
136 ////////////////////////////////////////////////////////////////////////////////
137 // environment support
138
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 }
148
149
150 // Return true if user is running as root.
151
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 }
161
162
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
177
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
194
195
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 }
213
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.";
222
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 }
239
240 void os::init_system_properties_values() {
241 // char arch[12];
242 // sysinfo(SI_ARCHITECTURE, arch, sizeof(arch));
243
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.
269
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)
273
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 #define DEFAULT_LIBPATH "/lib:/usr/lib"
283
284 #define EXTENSIONS_DIR "/lib/ext"
285 #define ENDORSED_DIR "/lib/endorsed"
286 #define REG_DIR "/usr/java/packages"
287
288 {
289 /* sysclasspath, java_home, dll_dir */
290 {
291 char *home_path;
292 char *dll_path;
293 char *pslash;
294 char buf[MAXPATHLEN];
295 os::jvm_path(buf, sizeof(buf));
296
297 // Found the full path to libjvm.so.
298 // Now cut the path to <java_home>/jre if we can.
299 *(strrchr(buf, '/')) = '\0'; /* get rid of /libjvm.so */
300 pslash = strrchr(buf, '/');
301 if (pslash != NULL)
302 *pslash = '\0'; /* get rid of /{client|server|hotspot} */
303 dll_path = malloc(strlen(buf) + 1);
304 if (dll_path == NULL)
305 return;
306 strcpy(dll_path, buf);
307 Arguments::set_dll_dir(dll_path);
308
309 if (pslash != NULL) {
310 pslash = strrchr(buf, '/');
311 if (pslash != NULL) {
312 *pslash = '\0'; /* get rid of /<arch> */
313 pslash = strrchr(buf, '/');
314 if (pslash != NULL)
315 *pslash = '\0'; /* get rid of /lib */
316 }
317 }
318
319 home_path = malloc(strlen(buf) + 1);
320 if (home_path == NULL)
321 return;
322 strcpy(home_path, buf);
323 Arguments::set_java_home(home_path);
324
325 if (!set_boot_path('/', ':'))
326 return;
327 }
328
329 /*
330 * Where to look for native libraries
331 *
332 * Note: Due to a legacy implementation, most of the library path
333 * is set in the launcher. This was to accomodate linking restrictions
334 * on legacy Linux implementations (which are no longer supported).
335 * Eventually, all the library path setting will be done here.
336 *
337 * However, to prevent the proliferation of improperly built native
338 * libraries, the new path component /usr/java/packages is added here.
339 * Eventually, all the library path setting will be done here.
340 */
341 {
342 char *ld_library_path;
343
344 /*
345 * Construct the invariant part of ld_library_path. Note that the
346 * space for the colon and the trailing null are provided by the
347 * nulls included by the sizeof operator (so actually we allocate
348 * a byte more than necessary).
349 */
350 ld_library_path = (char *) malloc(sizeof(REG_DIR) + sizeof("/lib/") +
351 strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH));
352 sprintf(ld_library_path, REG_DIR "/lib/%s:" DEFAULT_LIBPATH, cpu_arch);
353
354 /*
355 * Get the user setting of LD_LIBRARY_PATH, and prepended it. It
356 * should always exist (until the legacy problem cited above is
357 * addressed).
358 */
359 char *v = getenv("LD_LIBRARY_PATH");
360 if (v != NULL) {
361 char *t = ld_library_path;
362 /* That's +1 for the colon and +1 for the trailing '\0' */
363 ld_library_path = (char *) malloc(strlen(v) + 1 + strlen(t) + 1);
364 sprintf(ld_library_path, "%s:%s", v, t);
365 }
366 Arguments::set_library_path(ld_library_path);
367 }
368
369 /*
370 * Extensions directories.
371 *
372 * Note that the space for the colon and the trailing null are provided
373 * by the nulls included by the sizeof operator (so actually one byte more
374 * than necessary is allocated).
375 */
376 {
377 char *buf = malloc(strlen(Arguments::get_java_home()) +
378 sizeof(EXTENSIONS_DIR) + sizeof(REG_DIR) + sizeof(EXTENSIONS_DIR));
379 sprintf(buf, "%s" EXTENSIONS_DIR ":" REG_DIR EXTENSIONS_DIR,
380 Arguments::get_java_home());
381 Arguments::set_ext_dirs(buf);
382 }
383
384 /* Endorsed standards default directory. */
385 {
386 char * buf;
387 buf = malloc(strlen(Arguments::get_java_home()) + sizeof(ENDORSED_DIR));
388 sprintf(buf, "%s" ENDORSED_DIR, Arguments::get_java_home());
389 Arguments::set_endorsed_dirs(buf);
390 }
391 }
392
393 #undef malloc
394 #undef getenv
395 #undef EXTENSIONS_DIR
396 #undef ENDORSED_DIR
397
398 // Done
399 return;
400 }
401
402 ////////////////////////////////////////////////////////////////////////////////
403 // breakpoint support
404
405 void os::breakpoint() {
406 BREAKPOINT;
407 }
408
409 extern "C" void breakpoint() {
410 // use debugger to set breakpoint here
411 }
412
413 ////////////////////////////////////////////////////////////////////////////////
414 // signal support
415
416 debug_only(static bool signal_sets_initialized = false);
417 static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs;
418
419 bool os::Linux::is_sig_ignored(int sig) {
420 struct sigaction oact;
421 sigaction(sig, (struct sigaction*)NULL, &oact);
422 void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*, oact.sa_sigaction)
423 : CAST_FROM_FN_PTR(void*, oact.sa_handler);
424 if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN))
425 return true;
426 else
427 return false;
428 }
429
430 void os::Linux::signal_sets_init() {
431 // Should also have an assertion stating we are still single-threaded.
432 assert(!signal_sets_initialized, "Already initialized");
433 // Fill in signals that are necessarily unblocked for all threads in
434 // the VM. Currently, we unblock the following signals:
435 // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden
436 // by -Xrs (=ReduceSignalUsage));
437 // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all
438 // other threads. The "ReduceSignalUsage" boolean tells us not to alter
439 // the dispositions or masks wrt these signals.
440 // Programs embedding the VM that want to use the above signals for their
441 // own purposes must, at this time, use the "-Xrs" option to prevent
442 // interference with shutdown hooks and BREAK_SIGNAL thread dumping.
443 // (See bug 4345157, and other related bugs).
444 // In reality, though, unblocking these signals is really a nop, since
445 // these signals are not blocked by default.
446 sigemptyset(&unblocked_sigs);
447 sigemptyset(&allowdebug_blocked_sigs);
448 sigaddset(&unblocked_sigs, SIGILL);
449 sigaddset(&unblocked_sigs, SIGSEGV);
450 sigaddset(&unblocked_sigs, SIGBUS);
451 sigaddset(&unblocked_sigs, SIGFPE);
452 sigaddset(&unblocked_sigs, SR_signum);
453
454 if (!ReduceSignalUsage) {
455 if (!os::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) {
456 sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL);
457 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL);
458 }
459 if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) {
460 sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL);
461 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL);
462 }
463 if (!os::Linux::is_sig_ignored(SHUTDOWN3_SIGNAL)) {
464 sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL);
465 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN3_SIGNAL);
466 }
467 }
468 // Fill in signals that are blocked by all but the VM thread.
469 sigemptyset(&vm_sigs);
470 if (!ReduceSignalUsage)
471 sigaddset(&vm_sigs, BREAK_SIGNAL);
472 debug_only(signal_sets_initialized = true);
473
474 }
475
476 // These are signals that are unblocked while a thread is running Java.
477 // (For some reason, they get blocked by default.)
478 sigset_t* os::Linux::unblocked_signals() {
479 assert(signal_sets_initialized, "Not initialized");
480 return &unblocked_sigs;
481 }
482
483 // These are the signals that are blocked while a (non-VM) thread is
484 // running Java. Only the VM thread handles these signals.
485 sigset_t* os::Linux::vm_signals() {
486 assert(signal_sets_initialized, "Not initialized");
487 return &vm_sigs;
488 }
489
490 // These are signals that are blocked during cond_wait to allow debugger in
491 sigset_t* os::Linux::allowdebug_blocked_signals() {
492 assert(signal_sets_initialized, "Not initialized");
493 return &allowdebug_blocked_sigs;
494 }
495
496 void os::Linux::hotspot_sigmask(Thread* thread) {
497
498 //Save caller's signal mask before setting VM signal mask
499 sigset_t caller_sigmask;
500 pthread_sigmask(SIG_BLOCK, NULL, &caller_sigmask);
501
502 OSThread* osthread = thread->osthread();
503 osthread->set_caller_sigmask(caller_sigmask);
504
505 pthread_sigmask(SIG_UNBLOCK, os::Linux::unblocked_signals(), NULL);
506
507 if (!ReduceSignalUsage) {
508 if (thread->is_VM_thread()) {
509 // Only the VM thread handles BREAK_SIGNAL ...
510 pthread_sigmask(SIG_UNBLOCK, vm_signals(), NULL);
511 } else {
512 // ... all other threads block BREAK_SIGNAL
513 pthread_sigmask(SIG_BLOCK, vm_signals(), NULL);
514 }
515 }
516 }
517
518 //////////////////////////////////////////////////////////////////////////////
519 // detecting pthread library
520
521 void os::Linux::libpthread_init() {
522 // Save glibc and pthread version strings. Note that _CS_GNU_LIBC_VERSION
523 // and _CS_GNU_LIBPTHREAD_VERSION are supported in glibc >= 2.3.2. Use a
524 // generic name for earlier versions.
525 // Define macros here so we can build HotSpot on old systems.
526 # ifndef _CS_GNU_LIBC_VERSION
527 # define _CS_GNU_LIBC_VERSION 2
528 # endif
529 # ifndef _CS_GNU_LIBPTHREAD_VERSION
530 # define _CS_GNU_LIBPTHREAD_VERSION 3
531 # endif
532
533 size_t n = confstr(_CS_GNU_LIBC_VERSION, NULL, 0);
534 if (n > 0) {
535 char *str = (char *)malloc(n);
536 confstr(_CS_GNU_LIBC_VERSION, str, n);
537 os::Linux::set_glibc_version(str);
538 } else {
539 // _CS_GNU_LIBC_VERSION is not supported, try gnu_get_libc_version()
540 static char _gnu_libc_version[32];
541 jio_snprintf(_gnu_libc_version, sizeof(_gnu_libc_version),
542 "glibc %s %s", gnu_get_libc_version(), gnu_get_libc_release());
543 os::Linux::set_glibc_version(_gnu_libc_version);
544 }
545
546 n = confstr(_CS_GNU_LIBPTHREAD_VERSION, NULL, 0);
547 if (n > 0) {
548 char *str = (char *)malloc(n);
549 confstr(_CS_GNU_LIBPTHREAD_VERSION, str, n);
550 // Vanilla RH-9 (glibc 2.3.2) has a bug that confstr() always tells
551 // us "NPTL-0.29" even we are running with LinuxThreads. Check if this
552 // is the case. LinuxThreads has a hard limit on max number of threads.
553 // So sysconf(_SC_THREAD_THREADS_MAX) will return a positive value.
554 // On the other hand, NPTL does not have such a limit, sysconf()
555 // will return -1 and errno is not changed. Check if it is really NPTL.
556 if (strcmp(os::Linux::glibc_version(), "glibc 2.3.2") == 0 &&
557 strstr(str, "NPTL") &&
558 sysconf(_SC_THREAD_THREADS_MAX) > 0) {
559 free(str);
560 os::Linux::set_libpthread_version("linuxthreads");
561 } else {
562 os::Linux::set_libpthread_version(str);
563 }
564 } else {
565 // glibc before 2.3.2 only has LinuxThreads.
566 os::Linux::set_libpthread_version("linuxthreads");
567 }
568
569 if (strstr(libpthread_version(), "NPTL")) {
570 os::Linux::set_is_NPTL();
571 } else {
572 os::Linux::set_is_LinuxThreads();
573 }
574
575 // LinuxThreads have two flavors: floating-stack mode, which allows variable
576 // stack size; and fixed-stack mode. NPTL is always floating-stack.
577 if (os::Linux::is_NPTL() || os::Linux::supports_variable_stack_size()) {
578 os::Linux::set_is_floating_stack();
579 }
580 }
581
582 /////////////////////////////////////////////////////////////////////////////
583 // thread stack
584
585 // Force Linux kernel to expand current thread stack. If "bottom" is close
586 // to the stack guard, caller should block all signals.
587 //
588 // MAP_GROWSDOWN:
589 // A special mmap() flag that is used to implement thread stacks. It tells
590 // kernel that the memory region should extend downwards when needed. This
591 // allows early versions of LinuxThreads to only mmap the first few pages
592 // when creating a new thread. Linux kernel will automatically expand thread
593 // stack as needed (on page faults).
594 //
595 // However, because the memory region of a MAP_GROWSDOWN stack can grow on
596 // demand, if a page fault happens outside an already mapped MAP_GROWSDOWN
597 // region, it's hard to tell if the fault is due to a legitimate stack
598 // access or because of reading/writing non-exist memory (e.g. buffer
599 // overrun). As a rule, if the fault happens below current stack pointer,
600 // Linux kernel does not expand stack, instead a SIGSEGV is sent to the
601 // application (see Linux kernel fault.c).
602 //
603 // This Linux feature can cause SIGSEGV when VM bangs thread stack for
604 // stack overflow detection.
605 //
606 // Newer version of LinuxThreads (since glibc-2.2, or, RH-7.x) and NPTL do
607 // not use this flag. However, the stack of initial thread is not created
608 // by pthread, it is still MAP_GROWSDOWN. Also it's possible (though
609 // unlikely) that user code can create a thread with MAP_GROWSDOWN stack
610 // and then attach the thread to JVM.
611 //
612 // To get around the problem and allow stack banging on Linux, we need to
613 // manually expand thread stack after receiving the SIGSEGV.
614 //
615 // There are two ways to expand thread stack to address "bottom", we used
616 // both of them in JVM before 1.5:
617 // 1. adjust stack pointer first so that it is below "bottom", and then
618 // touch "bottom"
619 // 2. mmap() the page in question
620 //
621 // Now alternate signal stack is gone, it's harder to use 2. For instance,
622 // if current sp is already near the lower end of page 101, and we need to
623 // call mmap() to map page 100, it is possible that part of the mmap() frame
624 // will be placed in page 100. When page 100 is mapped, it is zero-filled.
625 // That will destroy the mmap() frame and cause VM to crash.
626 //
627 // The following code works by adjusting sp first, then accessing the "bottom"
628 // page to force a page fault. Linux kernel will then automatically expand the
629 // stack mapping.
630 //
631 // _expand_stack_to() assumes its frame size is less than page size, which
632 // should always be true if the function is not inlined.
633
634 #if __GNUC__ < 3 // gcc 2.x does not support noinline attribute
635 #define NOINLINE
636 #else
637 #define NOINLINE __attribute__ ((noinline))
638 #endif
639
640 static void _expand_stack_to(address bottom) NOINLINE;
641
642 static void _expand_stack_to(address bottom) {
643 address sp;
644 size_t size;
645 volatile char *p;
646
647 // Adjust bottom to point to the largest address within the same page, it
648 // gives us a one-page buffer if alloca() allocates slightly more memory.
649 bottom = (address)align_size_down((uintptr_t)bottom, os::Linux::page_size());
650 bottom += os::Linux::page_size() - 1;
651
652 // sp might be slightly above current stack pointer; if that's the case, we
653 // will alloca() a little more space than necessary, which is OK. Don't use
654 // os::current_stack_pointer(), as its result can be slightly below current
655 // stack pointer, causing us to not alloca enough to reach "bottom".
656 sp = (address)&sp;
657
658 if (sp > bottom) {
659 size = sp - bottom;
660 p = (volatile char *)alloca(size);
661 assert(p != NULL && p <= (volatile char *)bottom, "alloca problem?");
662 p[0] = '\0';
663 }
664 }
665
666 bool os::Linux::manually_expand_stack(JavaThread * t, address addr) {
667 assert(t!=NULL, "just checking");
668 assert(t->osthread()->expanding_stack(), "expand should be set");
669 assert(t->stack_base() != NULL, "stack_base was not initialized");
670
671 if (addr < t->stack_base() && addr >= t->stack_yellow_zone_base()) {
672 sigset_t mask_all, old_sigset;
673 sigfillset(&mask_all);
674 pthread_sigmask(SIG_SETMASK, &mask_all, &old_sigset);
675 _expand_stack_to(addr);
676 pthread_sigmask(SIG_SETMASK, &old_sigset, NULL);
677 return true;
678 }
679 return false;
680 }
681
682 //////////////////////////////////////////////////////////////////////////////
683 // create new thread
684
685 static address highest_vm_reserved_address();
686
687 // check if it's safe to start a new thread
688 static bool _thread_safety_check(Thread* thread) {
689 if (os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack()) {
690 // Fixed stack LinuxThreads (SuSE Linux/x86, and some versions of Redhat)
691 // Heap is mmap'ed at lower end of memory space. Thread stacks are
692 // allocated (MAP_FIXED) from high address space. Every thread stack
693 // occupies a fixed size slot (usually 2Mbytes, but user can change
694 // it to other values if they rebuild LinuxThreads).
695 //
696 // Problem with MAP_FIXED is that mmap() can still succeed even part of
697 // the memory region has already been mmap'ed. That means if we have too
698 // many threads and/or very large heap, eventually thread stack will
699 // collide with heap.
700 //
701 // Here we try to prevent heap/stack collision by comparing current
702 // stack bottom with the highest address that has been mmap'ed by JVM
703 // plus a safety margin for memory maps created by native code.
704 //
705 // This feature can be disabled by setting ThreadSafetyMargin to 0
706 //
707 if (ThreadSafetyMargin > 0) {
708 address stack_bottom = os::current_stack_base() - os::current_stack_size();
709
710 // not safe if our stack extends below the safety margin
711 return stack_bottom - ThreadSafetyMargin >= highest_vm_reserved_address();
712 } else {
713 return true;
714 }
715 } else {
716 // Floating stack LinuxThreads or NPTL:
717 // Unlike fixed stack LinuxThreads, thread stacks are not MAP_FIXED. When
718 // there's not enough space left, pthread_create() will fail. If we come
719 // here, that means enough space has been reserved for stack.
720 return true;
721 }
722 }
723
724 // Thread start routine for all newly created threads
725 static void *java_start(Thread *thread) {
726 // Try to randomize the cache line index of hot stack frames.
727 // This helps when threads of the same stack traces evict each other's
728 // cache lines. The threads can be either from the same JVM instance, or
729 // from different JVM instances. The benefit is especially true for
730 // processors with hyperthreading technology.
731 static int counter = 0;
732 int pid = os::current_process_id();
733 alloca(((pid ^ counter++) & 7) * 128);
734
735 ThreadLocalStorage::set_thread(thread);
736
737 OSThread* osthread = thread->osthread();
738 Monitor* sync = osthread->startThread_lock();
739
740 // non floating stack LinuxThreads needs extra check, see above
741 if (!_thread_safety_check(thread)) {
742 // notify parent thread
743 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
744 osthread->set_state(ZOMBIE);
745 sync->notify_all();
746 return NULL;
747 }
748
749 // thread_id is kernel thread id (similar to Solaris LWP id)
750 osthread->set_thread_id(os::Linux::gettid());
751
752 if (UseNUMA) {
753 int lgrp_id = os::numa_get_group_id();
754 if (lgrp_id != -1) {
755 thread->set_lgrp_id(lgrp_id);
756 }
757 }
758 // initialize signal mask for this thread
759 os::Linux::hotspot_sigmask(thread);
760
761 // initialize floating point control register
762 os::Linux::init_thread_fpu_state();
763
764 // handshaking with parent thread
765 {
766 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
767
768 // notify parent thread
769 osthread->set_state(INITIALIZED);
770 sync->notify_all();
771
772 // wait until os::start_thread()
773 while (osthread->get_state() == INITIALIZED) {
774 sync->wait(Mutex::_no_safepoint_check_flag);
775 }
776 }
777
778 // call one more level start routine
779 thread->run();
780
781 return 0;
782 }
783
784 bool os::create_thread(Thread* thread, ThreadType thr_type, size_t stack_size) {
785 assert(thread->osthread() == NULL, "caller responsible");
786
787 // Allocate the OSThread object
788 OSThread* osthread = new OSThread(NULL, NULL);
789 if (osthread == NULL) {
790 return false;
791 }
792
793 // set the correct thread state
794 osthread->set_thread_type(thr_type);
795
796 // Initial state is ALLOCATED but not INITIALIZED
797 osthread->set_state(ALLOCATED);
798
799 thread->set_osthread(osthread);
800
801 // init thread attributes
802 pthread_attr_t attr;
803 pthread_attr_init(&attr);
804 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
805
806 // stack size
807 if (os::Linux::supports_variable_stack_size()) {
808 // calculate stack size if it's not specified by caller
809 if (stack_size == 0) {
810 stack_size = os::Linux::default_stack_size(thr_type);
811
812 switch (thr_type) {
813 case os::java_thread:
814 // Java threads use ThreadStackSize which default value can be changed with the flag -Xss
815 if (JavaThread::stack_size_at_create() > 0) stack_size = JavaThread::stack_size_at_create();
816 break;
817 case os::compiler_thread:
818 if (CompilerThreadStackSize > 0) {
819 stack_size = (size_t)(CompilerThreadStackSize * K);
820 break;
821 } // else fall through:
822 // use VMThreadStackSize if CompilerThreadStackSize is not defined
823 case os::vm_thread:
824 case os::pgc_thread:
825 case os::cgc_thread:
826 case os::watcher_thread:
827 if (VMThreadStackSize > 0) stack_size = (size_t)(VMThreadStackSize * K);
828 break;
829 }
830 }
831
832 stack_size = MAX2(stack_size, os::Linux::min_stack_allowed);
833 pthread_attr_setstacksize(&attr, stack_size);
834 } else {
835 // let pthread_create() pick the default value.
836 }
837
838 // glibc guard page
839 pthread_attr_setguardsize(&attr, os::Linux::default_guard_size(thr_type));
840
841 ThreadState state;
842
843 {
844 // Serialize thread creation if we are running with fixed stack LinuxThreads
845 bool lock = os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack();
846 if (lock) {
847 os::Linux::createThread_lock()->lock_without_safepoint_check();
848 }
849
850 pthread_t tid;
851 int ret = pthread_create(&tid, &attr, (void* (*)(void*)) java_start, thread);
852
853 pthread_attr_destroy(&attr);
854
855 if (ret != 0) {
856 if (PrintMiscellaneous && (Verbose || WizardMode)) {
857 perror("pthread_create()");
858 }
859 // Need to clean up stuff we've allocated so far
860 thread->set_osthread(NULL);
861 delete osthread;
862 if (lock) os::Linux::createThread_lock()->unlock();
863 return false;
864 }
865
866 // Store pthread info into the OSThread
867 osthread->set_pthread_id(tid);
868
869 // Wait until child thread is either initialized or aborted
870 {
871 Monitor* sync_with_child = osthread->startThread_lock();
872 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
873 while ((state = osthread->get_state()) == ALLOCATED) {
874 sync_with_child->wait(Mutex::_no_safepoint_check_flag);
875 }
876 }
877
878 if (lock) {
879 os::Linux::createThread_lock()->unlock();
880 }
881 }
882
883 // Aborted due to thread limit being reached
884 if (state == ZOMBIE) {
885 thread->set_osthread(NULL);
886 delete osthread;
887 return false;
888 }
889
890 // The thread is returned suspended (in state INITIALIZED),
891 // and is started higher up in the call chain
892 assert(state == INITIALIZED, "race condition");
893 return true;
894 }
895
896 /////////////////////////////////////////////////////////////////////////////
897 // attach existing thread
898
899 // bootstrap the main thread
900 bool os::create_main_thread(JavaThread* thread) {
901 assert(os::Linux::_main_thread == pthread_self(), "should be called inside main thread");
902 return create_attached_thread(thread);
903 }
904
905 bool os::create_attached_thread(JavaThread* thread) {
906 #ifdef ASSERT
907 thread->verify_not_published();
908 #endif
909
910 // Allocate the OSThread object
911 OSThread* osthread = new OSThread(NULL, NULL);
912
913 if (osthread == NULL) {
914 return false;
915 }
916
917 // Store pthread info into the OSThread
918 osthread->set_thread_id(os::Linux::gettid());
919 osthread->set_pthread_id(::pthread_self());
920
921 // initialize floating point control register
922 os::Linux::init_thread_fpu_state();
923
924 // Initial thread state is RUNNABLE
925 osthread->set_state(RUNNABLE);
926
927 thread->set_osthread(osthread);
928
929 if (UseNUMA) {
930 int lgrp_id = os::numa_get_group_id();
931 if (lgrp_id != -1) {
932 thread->set_lgrp_id(lgrp_id);
933 }
934 }
935
936 if (os::Linux::is_initial_thread()) {
937 // If current thread is initial thread, its stack is mapped on demand,
938 // see notes about MAP_GROWSDOWN. Here we try to force kernel to map
939 // the entire stack region to avoid SEGV in stack banging.
940 // It is also useful to get around the heap-stack-gap problem on SuSE
941 // kernel (see 4821821 for details). We first expand stack to the top
942 // of yellow zone, then enable stack yellow zone (order is significant,
943 // enabling yellow zone first will crash JVM on SuSE Linux), so there
944 // is no gap between the last two virtual memory regions.
945
946 JavaThread *jt = (JavaThread *)thread;
947 address addr = jt->stack_yellow_zone_base();
948 assert(addr != NULL, "initialization problem?");
949 assert(jt->stack_available(addr) > 0, "stack guard should not be enabled");
950
951 osthread->set_expanding_stack();
952 os::Linux::manually_expand_stack(jt, addr);
953 osthread->clear_expanding_stack();
954 }
955
956 // initialize signal mask for this thread
957 // and save the caller's signal mask
958 os::Linux::hotspot_sigmask(thread);
959
960 return true;
961 }
962
963 void os::pd_start_thread(Thread* thread) {
964 OSThread * osthread = thread->osthread();
965 assert(osthread->get_state() != INITIALIZED, "just checking");
966 Monitor* sync_with_child = osthread->startThread_lock();
967 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
968 sync_with_child->notify();
969 }
970
971 // Free Linux resources related to the OSThread
972 void os::free_thread(OSThread* osthread) {
973 assert(osthread != NULL, "osthread not set");
974
975 if (Thread::current()->osthread() == osthread) {
976 // Restore caller's signal mask
977 sigset_t sigmask = osthread->caller_sigmask();
978 pthread_sigmask(SIG_SETMASK, &sigmask, NULL);
979 }
980
981 delete osthread;
982 }
983
984 //////////////////////////////////////////////////////////////////////////////
985 // thread local storage
986
987 int os::allocate_thread_local_storage() {
988 pthread_key_t key;
989 int rslt = pthread_key_create(&key, NULL);
990 assert(rslt == 0, "cannot allocate thread local storage");
991 return (int)key;
992 }
993
994 // Note: This is currently not used by VM, as we don't destroy TLS key
995 // on VM exit.
996 void os::free_thread_local_storage(int index) {
997 int rslt = pthread_key_delete((pthread_key_t)index);
998 assert(rslt == 0, "invalid index");
999 }
1000
1001 void os::thread_local_storage_at_put(int index, void* value) {
1002 int rslt = pthread_setspecific((pthread_key_t)index, value);
1003 assert(rslt == 0, "pthread_setspecific failed");
1004 }
1005
1006 extern "C" Thread* get_thread() {
1007 return ThreadLocalStorage::thread();
1008 }
1009
1010 //////////////////////////////////////////////////////////////////////////////
1011 // initial thread
1012
1013 // Check if current thread is the initial thread, similar to Solaris thr_main.
1014 bool os::Linux::is_initial_thread(void) {
1015 char dummy;
1016 // If called before init complete, thread stack bottom will be null.
1017 // Can be called if fatal error occurs before initialization.
1018 if (initial_thread_stack_bottom() == NULL) return false;
1019 assert(initial_thread_stack_bottom() != NULL &&
1020 initial_thread_stack_size() != 0,
1021 "os::init did not locate initial thread's stack region");
1022 if ((address)&dummy >= initial_thread_stack_bottom() &&
1023 (address)&dummy < initial_thread_stack_bottom() + initial_thread_stack_size())
1024 return true;
1025 else return false;
1026 }
1027
1028 // Find the virtual memory area that contains addr
1029 static bool find_vma(address addr, address* vma_low, address* vma_high) {
1030 FILE *fp = fopen("/proc/self/maps", "r");
1031 if (fp) {
1032 address low, high;
1033 while (!feof(fp)) {
1034 if (fscanf(fp, "%p-%p", &low, &high) == 2) {
1035 if (low <= addr && addr < high) {
1036 if (vma_low) *vma_low = low;
1037 if (vma_high) *vma_high = high;
1038 fclose (fp);
1039 return true;
1040 }
1041 }
1042 for (;;) {
1043 int ch = fgetc(fp);
1044 if (ch == EOF || ch == (int)'\n') break;
1045 }
1046 }
1047 fclose(fp);
1048 }
1049 return false;
1050 }
1051
1052 // Locate initial thread stack. This special handling of initial thread stack
1053 // is needed because pthread_getattr_np() on most (all?) Linux distros returns
1054 // bogus value for initial thread.
1055 void os::Linux::capture_initial_stack(size_t max_size) {
1056 // stack size is the easy part, get it from RLIMIT_STACK
1057 size_t stack_size;
1058 struct rlimit rlim;
1059 getrlimit(RLIMIT_STACK, &rlim);
1060 stack_size = rlim.rlim_cur;
1061
1062 // 6308388: a bug in ld.so will relocate its own .data section to the
1063 // lower end of primordial stack; reduce ulimit -s value a little bit
1064 // so we won't install guard page on ld.so's data section.
1065 stack_size -= 2 * page_size();
1066
1067 // 4441425: avoid crash with "unlimited" stack size on SuSE 7.1 or Redhat
1068 // 7.1, in both cases we will get 2G in return value.
1069 // 4466587: glibc 2.2.x compiled w/o "--enable-kernel=2.4.0" (RH 7.0,
1070 // SuSE 7.2, Debian) can not handle alternate signal stack correctly
1071 // for initial thread if its stack size exceeds 6M. Cap it at 2M,
1072 // in case other parts in glibc still assumes 2M max stack size.
1073 // FIXME: alt signal stack is gone, maybe we can relax this constraint?
1074 #ifndef IA64
1075 if (stack_size > 2 * K * K) stack_size = 2 * K * K;
1076 #else
1077 // Problem still exists RH7.2 (IA64 anyway) but 2MB is a little small
1078 if (stack_size > 4 * K * K) stack_size = 4 * K * K;
1079 #endif
1080
1081 // Try to figure out where the stack base (top) is. This is harder.
1082 //
1083 // When an application is started, glibc saves the initial stack pointer in
1084 // a global variable "__libc_stack_end", which is then used by system
1085 // libraries. __libc_stack_end should be pretty close to stack top. The
1086 // variable is available since the very early days. However, because it is
1087 // a private interface, it could disappear in the future.
1088 //
1089 // Linux kernel saves start_stack information in /proc/<pid>/stat. Similar
1090 // to __libc_stack_end, it is very close to stack top, but isn't the real
1091 // stack top. Note that /proc may not exist if VM is running as a chroot
1092 // program, so reading /proc/<pid>/stat could fail. Also the contents of
1093 // /proc/<pid>/stat could change in the future (though unlikely).
1094 //
1095 // We try __libc_stack_end first. If that doesn't work, look for
1096 // /proc/<pid>/stat. If neither of them works, we use current stack pointer
1097 // as a hint, which should work well in most cases.
1098
1099 uintptr_t stack_start;
1100
1101 // try __libc_stack_end first
1102 uintptr_t *p = (uintptr_t *)dlsym(RTLD_DEFAULT, "__libc_stack_end");
1103 if (p && *p) {
1104 stack_start = *p;
1105 } else {
1106 // see if we can get the start_stack field from /proc/self/stat
1107 FILE *fp;
1108 int pid;
1109 char state;
1110 int ppid;
1111 int pgrp;
1112 int session;
1113 int nr;
1114 int tpgrp;
1115 unsigned long flags;
1116 unsigned long minflt;
1117 unsigned long cminflt;
1118 unsigned long majflt;
1119 unsigned long cmajflt;
1120 unsigned long utime;
1121 unsigned long stime;
1122 long cutime;
1123 long cstime;
1124 long prio;
1125 long nice;
1126 long junk;
1127 long it_real;
1128 uintptr_t start;
1129 uintptr_t vsize;
1130 uintptr_t rss;
1131 unsigned long rsslim;
1132 uintptr_t scodes;
1133 uintptr_t ecode;
1134 int i;
1135
1136 // Figure what the primordial thread stack base is. Code is inspired
1137 // by email from Hans Boehm. /proc/self/stat begins with current pid,
1138 // followed by command name surrounded by parentheses, state, etc.
1139 char stat[2048];
1140 int statlen;
1141
1142 fp = fopen("/proc/self/stat", "r");
1143 if (fp) {
1144 statlen = fread(stat, 1, 2047, fp);
1145 stat[statlen] = '\0';
1146 fclose(fp);
1147
1148 // Skip pid and the command string. Note that we could be dealing with
1149 // weird command names, e.g. user could decide to rename java launcher
1150 // to "java 1.4.2 :)", then the stat file would look like
1151 // 1234 (java 1.4.2 :)) R ... ...
1152 // We don't really need to know the command string, just find the last
1153 // occurrence of ")" and then start parsing from there. See bug 4726580.
1154 char * s = strrchr(stat, ')');
1155
1156 i = 0;
1157 if (s) {
1158 // Skip blank chars
1159 do s++; while (isspace(*s));
1160
1161 /* 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 */
1162 /* 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 */
1163 i = sscanf(s, "%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu %ld %ld %ld %ld %ld %ld %lu %lu %ld %lu %lu %lu %lu",
1164 &state, /* 3 %c */
1165 &ppid, /* 4 %d */
1166 &pgrp, /* 5 %d */
1167 &session, /* 6 %d */
1168 &nr, /* 7 %d */
1169 &tpgrp, /* 8 %d */
1170 &flags, /* 9 %lu */
1171 &minflt, /* 10 %lu */
1172 &cminflt, /* 11 %lu */
1173 &majflt, /* 12 %lu */
1174 &cmajflt, /* 13 %lu */
1175 &utime, /* 14 %lu */
1176 &stime, /* 15 %lu */
1177 &cutime, /* 16 %ld */
1178 &cstime, /* 17 %ld */
1179 &prio, /* 18 %ld */
1180 &nice, /* 19 %ld */
1181 &junk, /* 20 %ld */
1182 &it_real, /* 21 %ld */
1183 &start, /* 22 %lu */
1184 &vsize, /* 23 %lu */
1185 &rss, /* 24 %ld */
1186 &rsslim, /* 25 %lu */
1187 &scodes, /* 26 %lu */
1188 &ecode, /* 27 %lu */
1189 &stack_start); /* 28 %lu */
1190 }
1191
1192 if (i != 28 - 2) {
1193 assert(false, "Bad conversion from /proc/self/stat");
1194 // product mode - assume we are the initial thread, good luck in the
1195 // embedded case.
1196 warning("Can't detect initial thread stack location - bad conversion");
1197 stack_start = (uintptr_t) &rlim;
1198 }
1199 } else {
1200 // For some reason we can't open /proc/self/stat (for example, running on
1201 // FreeBSD with a Linux emulator, or inside chroot), this should work for
1202 // most cases, so don't abort:
1203 warning("Can't detect initial thread stack location - no /proc/self/stat");
1204 stack_start = (uintptr_t) &rlim;
1205 }
1206 }
1207
1208 // Now we have a pointer (stack_start) very close to the stack top, the
1209 // next thing to do is to figure out the exact location of stack top. We
1210 // can find out the virtual memory area that contains stack_start by
1211 // reading /proc/self/maps, it should be the last vma in /proc/self/maps,
1212 // and its upper limit is the real stack top. (again, this would fail if
1213 // running inside chroot, because /proc may not exist.)
1214
1215 uintptr_t stack_top;
1216 address low, high;
1217 if (find_vma((address)stack_start, &low, &high)) {
1218 // success, "high" is the true stack top. (ignore "low", because initial
1219 // thread stack grows on demand, its real bottom is high - RLIMIT_STACK.)
1220 stack_top = (uintptr_t)high;
1221 } else {
1222 // failed, likely because /proc/self/maps does not exist
1223 warning("Can't detect initial thread stack location - find_vma failed");
1224 // best effort: stack_start is normally within a few pages below the real
1225 // stack top, use it as stack top, and reduce stack size so we won't put
1226 // guard page outside stack.
1227 stack_top = stack_start;
1228 stack_size -= 16 * page_size();
1229 }
1230
1231 // stack_top could be partially down the page so align it
1232 stack_top = align_size_up(stack_top, page_size());
1233
1234 if (max_size && stack_size > max_size) {
1235 _initial_thread_stack_size = max_size;
1236 } else {
1237 _initial_thread_stack_size = stack_size;
1238 }
1239
1240 _initial_thread_stack_size = align_size_down(_initial_thread_stack_size, page_size());
1241 _initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size;
1242 }
1243
1244 ////////////////////////////////////////////////////////////////////////////////
1245 // time support
1246
1247 // Time since start-up in seconds to a fine granularity.
1248 // Used by VMSelfDestructTimer and the MemProfiler.
1249 double os::elapsedTime() {
1250
1251 return (double)(os::elapsed_counter()) * 0.000001;
1252 }
1253
1254 jlong os::elapsed_counter() {
1255 timeval time;
1256 int status = gettimeofday(&time, NULL);
1257 return jlong(time.tv_sec) * 1000 * 1000 + jlong(time.tv_usec) - initial_time_count;
1258 }
1259
1260 jlong os::elapsed_frequency() {
1261 return (1000 * 1000);
1262 }
1263
1264 // For now, we say that linux does not support vtime. I have no idea
1265 // whether it can actually be made to (DLD, 9/13/05).
1266
1267 bool os::supports_vtime() { return false; }
1268 bool os::enable_vtime() { return false; }
1269 bool os::vtime_enabled() { return false; }
1270 double os::elapsedVTime() {
1271 // better than nothing, but not much
1272 return elapsedTime();
1273 }
1274
1275 jlong os::javaTimeMillis() {
1276 timeval time;
1277 int status = gettimeofday(&time, NULL);
1278 assert(status != -1, "linux error");
1279 return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000);
1280 }
1281
1282 #ifndef CLOCK_MONOTONIC
1283 #define CLOCK_MONOTONIC (1)
1284 #endif
1285
1286 void os::Linux::clock_init() {
1287 // we do dlopen's in this particular order due to bug in linux
1288 // dynamical loader (see 6348968) leading to crash on exit
1289 void* handle = dlopen("librt.so.1", RTLD_LAZY);
1290 if (handle == NULL) {
1291 handle = dlopen("librt.so", RTLD_LAZY);
1292 }
1293
1294 if (handle) {
1295 int (*clock_getres_func)(clockid_t, struct timespec*) =
1296 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres");
1297 int (*clock_gettime_func)(clockid_t, struct timespec*) =
1298 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime");
1299 if (clock_getres_func && clock_gettime_func) {
1300 // See if monotonic clock is supported by the kernel. Note that some
1301 // early implementations simply return kernel jiffies (updated every
1302 // 1/100 or 1/1000 second). It would be bad to use such a low res clock
1303 // for nano time (though the monotonic property is still nice to have).
1304 // It's fixed in newer kernels, however clock_getres() still returns
1305 // 1/HZ. We check if clock_getres() works, but will ignore its reported
1306 // resolution for now. Hopefully as people move to new kernels, this
1307 // won't be a problem.
1308 struct timespec res;
1309 struct timespec tp;
1310 if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 &&
1311 clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) {
1312 // yes, monotonic clock is supported
1313 _clock_gettime = clock_gettime_func;
1314 } else {
1315 // close librt if there is no monotonic clock
1316 dlclose(handle);
1317 }
1318 }
1319 }
1320 }
1321
1322 #ifndef SYS_clock_getres
1323
1324 #if defined(IA32) || defined(AMD64)
1325 #define SYS_clock_getres IA32_ONLY(266) AMD64_ONLY(229)
1326 #else
1327 #error Value of SYS_clock_getres not known on this platform
1328 #endif
1329
1330 #endif
1331
1332 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y)
1333
1334 void os::Linux::fast_thread_clock_init() {
1335 if (!UseLinuxPosixThreadCPUClocks) {
1336 return;
1337 }
1338 clockid_t clockid;
1339 struct timespec tp;
1340 int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) =
1341 (int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid");
1342
1343 // Switch to using fast clocks for thread cpu time if
1344 // the sys_clock_getres() returns 0 error code.
1345 // Note, that some kernels may support the current thread
1346 // clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks
1347 // returned by the pthread_getcpuclockid().
1348 // If the fast Posix clocks are supported then the sys_clock_getres()
1349 // must return at least tp.tv_sec == 0 which means a resolution
1350 // better than 1 sec. This is extra check for reliability.
1351
1352 if(pthread_getcpuclockid_func &&
1353 pthread_getcpuclockid_func(_main_thread, &clockid) == 0 &&
1354 sys_clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) {
1355
1356 _supports_fast_thread_cpu_time = true;
1357 _pthread_getcpuclockid = pthread_getcpuclockid_func;
1358 }
1359 }
1360
1361 jlong os::javaTimeNanos() {
1362 if (Linux::supports_monotonic_clock()) {
1363 struct timespec tp;
1364 int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp);
1365 assert(status == 0, "gettime error");
1366 jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec);
1367 return result;
1368 } else {
1369 timeval time;
1370 int status = gettimeofday(&time, NULL);
1371 assert(status != -1, "linux error");
1372 jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec);
1373 return 1000 * usecs;
1374 }
1375 }
1376
1377 void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) {
1378 if (Linux::supports_monotonic_clock()) {
1379 info_ptr->max_value = ALL_64_BITS;
1380
1381 // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past
1382 info_ptr->may_skip_backward = false; // not subject to resetting or drifting
1383 info_ptr->may_skip_forward = false; // not subject to resetting or drifting
1384 } else {
1385 // gettimeofday - based on time in seconds since the Epoch thus does not wrap
1386 info_ptr->max_value = ALL_64_BITS;
1387
1388 // gettimeofday is a real time clock so it skips
1389 info_ptr->may_skip_backward = true;
1390 info_ptr->may_skip_forward = true;
1391 }
1392
1393 info_ptr->kind = JVMTI_TIMER_ELAPSED; // elapsed not CPU time
1394 }
1395
1396 // Return the real, user, and system times in seconds from an
1397 // arbitrary fixed point in the past.
1398 bool os::getTimesSecs(double* process_real_time,
1399 double* process_user_time,
1400 double* process_system_time) {
1401 struct tms ticks;
1402 clock_t real_ticks = times(&ticks);
1403
1404 if (real_ticks == (clock_t) (-1)) {
1405 return false;
1406 } else {
1407 double ticks_per_second = (double) clock_tics_per_sec;
1408 *process_user_time = ((double) ticks.tms_utime) / ticks_per_second;
1409 *process_system_time = ((double) ticks.tms_stime) / ticks_per_second;
1410 *process_real_time = ((double) real_ticks) / ticks_per_second;
1411
1412 return true;
1413 }
1414 }
1415
1416
1417 char * os::local_time_string(char *buf, size_t buflen) {
1418 struct tm t;
1419 time_t long_time;
1420 time(&long_time);
1421 localtime_r(&long_time, &t);
1422 jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d",
1423 t.tm_year + 1900, t.tm_mon + 1, t.tm_mday,
1424 t.tm_hour, t.tm_min, t.tm_sec);
1425 return buf;
1426 }
1427
1428 struct tm* os::localtime_pd(const time_t* clock, struct tm* res) {
1429 return localtime_r(clock, res);
1430 }
1431
1432 ////////////////////////////////////////////////////////////////////////////////
1433 // runtime exit support
1434
1435 // Note: os::shutdown() might be called very early during initialization, or
1436 // called from signal handler. Before adding something to os::shutdown(), make
1437 // sure it is async-safe and can handle partially initialized VM.
1438 void os::shutdown() {
1439
1440 // allow PerfMemory to attempt cleanup of any persistent resources
1441 perfMemory_exit();
1442
1443 // needs to remove object in file system
1444 AttachListener::abort();
1445
1446 // flush buffered output, finish log files
1447 ostream_abort();
1448
1449 // Check for abort hook
1450 abort_hook_t abort_hook = Arguments::abort_hook();
1451 if (abort_hook != NULL) {
1452 abort_hook();
1453 }
1454
1455 }
1456
1457 // Note: os::abort() might be called very early during initialization, or
1458 // called from signal handler. Before adding something to os::abort(), make
1459 // sure it is async-safe and can handle partially initialized VM.
1460 void os::abort(bool dump_core) {
1461 os::shutdown();
1462 if (dump_core) {
1463 #ifndef PRODUCT
1464 fdStream out(defaultStream::output_fd());
1465 out.print_raw("Current thread is ");
1466 char buf[16];
1467 jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id());
1468 out.print_raw_cr(buf);
1469 out.print_raw_cr("Dumping core ...");
1470 #endif
1471 ::abort(); // dump core
1472 }
1473
1474 ::exit(1);
1475 }
1476
1477 // Die immediately, no exit hook, no abort hook, no cleanup.
1478 void os::die() {
1479 // _exit() on LinuxThreads only kills current thread
1480 ::abort();
1481 }
1482
1483 // unused on linux for now.
1484 void os::set_error_file(const char *logfile) {}
1485
1486 intx os::current_thread_id() { return (intx)pthread_self(); }
1487 int os::current_process_id() {
1488
1489 // Under the old linux thread library, linux gives each thread
1490 // its own process id. Because of this each thread will return
1491 // a different pid if this method were to return the result
1492 // of getpid(2). Linux provides no api that returns the pid
1493 // of the launcher thread for the vm. This implementation
1494 // returns a unique pid, the pid of the launcher thread
1495 // that starts the vm 'process'.
1496
1497 // Under the NPTL, getpid() returns the same pid as the
1498 // launcher thread rather than a unique pid per thread.
1499 // Use gettid() if you want the old pre NPTL behaviour.
1500
1501 // if you are looking for the result of a call to getpid() that
1502 // returns a unique pid for the calling thread, then look at the
1503 // OSThread::thread_id() method in osThread_linux.hpp file
1504
1505 return (int)(_initial_pid ? _initial_pid : getpid());
1506 }
1507
1508 // DLL functions
1509
1510 const char* os::dll_file_extension() { return ".so"; }
1511
1512 const char* os::get_temp_directory() { return "/tmp/"; }
1513
1514 static bool file_exists(const char* filename) {
1515 struct stat statbuf;
1516 if (filename == NULL || strlen(filename) == 0) {
1517 return false;
1518 }
1519 return os::stat(filename, &statbuf) == 0;
1520 }
1521
1522 void os::dll_build_name(char* buffer, size_t buflen,
1523 const char* pname, const char* fname) {
1524 // Copied from libhpi
1525 const size_t pnamelen = pname ? strlen(pname) : 0;
1526
1527 // Quietly truncate on buffer overflow. Should be an error.
1528 if (pnamelen + strlen(fname) + 10 > (size_t) buflen) {
1529 *buffer = '\0';
1530 return;
1531 }
1532
1533 if (pnamelen == 0) {
1534 snprintf(buffer, buflen, "lib%s.so", fname);
1535 } else if (strchr(pname, *os::path_separator()) != NULL) {
1536 int n;
1537 char** pelements = split_path(pname, &n);
1538 for (int i = 0 ; i < n ; i++) {
1539 // Really shouldn't be NULL, but check can't hurt
1540 if (pelements[i] == NULL || strlen(pelements[i]) == 0) {
1541 continue; // skip the empty path values
1542 }
1543 snprintf(buffer, buflen, "%s/lib%s.so", pelements[i], fname);
1544 if (file_exists(buffer)) {
1545 break;
1546 }
1547 }
1548 // release the storage
1549 for (int i = 0 ; i < n ; i++) {
1550 if (pelements[i] != NULL) {
1551 FREE_C_HEAP_ARRAY(char, pelements[i]);
1552 }
1553 }
1554 if (pelements != NULL) {
1555 FREE_C_HEAP_ARRAY(char*, pelements);
1556 }
1557 } else {
1558 snprintf(buffer, buflen, "%s/lib%s.so", pname, fname);
1559 }
1560 }
1561
1562 const char* os::get_current_directory(char *buf, int buflen) {
1563 return getcwd(buf, buflen);
1564 }
1565
1566 // check if addr is inside libjvm[_g].so
1567 bool os::address_is_in_vm(address addr) {
1568 static address libjvm_base_addr;
1569 Dl_info dlinfo;
1570
1571 if (libjvm_base_addr == NULL) {
1572 dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo);
1573 libjvm_base_addr = (address)dlinfo.dli_fbase;
1574 assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm");
1575 }
1576
1577 if (dladdr((void *)addr, &dlinfo)) {
1578 if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true;
1579 }
1580
1581 return false;
1582 }
1583
1584 bool os::dll_address_to_function_name(address addr, char *buf,
1585 int buflen, int *offset) {
1586 Dl_info dlinfo;
1587
1588 if (dladdr((void*)addr, &dlinfo) && dlinfo.dli_sname != NULL) {
1589 if (buf) jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname);
1590 if (offset) *offset = addr - (address)dlinfo.dli_saddr;
1591 return true;
1592 } else {
1593 if (buf) buf[0] = '\0';
1594 if (offset) *offset = -1;
1595 return false;
1596 }
1597 }
1598
1599 struct _address_to_library_name {
1600 address addr; // input : memory address
1601 size_t buflen; // size of fname
1602 char* fname; // output: library name
1603 address base; // library base addr
1604 };
1605
1606 static int address_to_library_name_callback(struct dl_phdr_info *info,
1607 size_t size, void *data) {
1608 int i;
1609 bool found = false;
1610 address libbase = NULL;
1611 struct _address_to_library_name * d = (struct _address_to_library_name *)data;
1612
1613 // iterate through all loadable segments
1614 for (i = 0; i < info->dlpi_phnum; i++) {
1615 address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr);
1616 if (info->dlpi_phdr[i].p_type == PT_LOAD) {
1617 // base address of a library is the lowest address of its loaded
1618 // segments.
1619 if (libbase == NULL || libbase > segbase) {
1620 libbase = segbase;
1621 }
1622 // see if 'addr' is within current segment
1623 if (segbase <= d->addr &&
1624 d->addr < segbase + info->dlpi_phdr[i].p_memsz) {
1625 found = true;
1626 }
1627 }
1628 }
1629
1630 // dlpi_name is NULL or empty if the ELF file is executable, return 0
1631 // so dll_address_to_library_name() can fall through to use dladdr() which
1632 // can figure out executable name from argv[0].
1633 if (found && info->dlpi_name && info->dlpi_name[0]) {
1634 d->base = libbase;
1635 if (d->fname) {
1636 jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name);
1637 }
1638 return 1;
1639 }
1640 return 0;
1641 }
1642
1643 bool os::dll_address_to_library_name(address addr, char* buf,
1644 int buflen, int* offset) {
1645 Dl_info dlinfo;
1646 struct _address_to_library_name data;
1647
1648 // There is a bug in old glibc dladdr() implementation that it could resolve
1649 // to wrong library name if the .so file has a base address != NULL. Here
1650 // we iterate through the program headers of all loaded libraries to find
1651 // out which library 'addr' really belongs to. This workaround can be
1652 // removed once the minimum requirement for glibc is moved to 2.3.x.
1653 data.addr = addr;
1654 data.fname = buf;
1655 data.buflen = buflen;
1656 data.base = NULL;
1657 int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data);
1658
1659 if (rslt) {
1660 // buf already contains library name
1661 if (offset) *offset = addr - data.base;
1662 return true;
1663 } else if (dladdr((void*)addr, &dlinfo)){
1664 if (buf) jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname);
1665 if (offset) *offset = addr - (address)dlinfo.dli_fbase;
1666 return true;
1667 } else {
1668 if (buf) buf[0] = '\0';
1669 if (offset) *offset = -1;
1670 return false;
1671 }
1672 }
1673
1674 // Loads .dll/.so and
1675 // in case of error it checks if .dll/.so was built for the
1676 // same architecture as Hotspot is running on
1677
1678 void * os::dll_load(const char *filename, char *ebuf, int ebuflen)
1679 {
1680 void * result= ::dlopen(filename, RTLD_LAZY);
1681 if (result != NULL) {
1682 // Successful loading
1683 return result;
1684 }
1685
1686 Elf32_Ehdr elf_head;
1687
1688 // Read system error message into ebuf
1689 // It may or may not be overwritten below
1690 ::strncpy(ebuf, ::dlerror(), ebuflen-1);
1691 ebuf[ebuflen-1]='\0';
1692 int diag_msg_max_length=ebuflen-strlen(ebuf);
1693 char* diag_msg_buf=ebuf+strlen(ebuf);
1694
1695 if (diag_msg_max_length==0) {
1696 // No more space in ebuf for additional diagnostics message
1697 return NULL;
1698 }
1699
1700
1701 int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK);
1702
1703 if (file_descriptor < 0) {
1704 // Can't open library, report dlerror() message
1705 return NULL;
1706 }
1707
1708 bool failed_to_read_elf_head=
1709 (sizeof(elf_head)!=
1710 (::read(file_descriptor, &elf_head,sizeof(elf_head)))) ;
1711
1712 ::close(file_descriptor);
1713 if (failed_to_read_elf_head) {
1714 // file i/o error - report dlerror() msg
1715 return NULL;
1716 }
1717
1718 typedef struct {
1719 Elf32_Half code; // Actual value as defined in elf.h
1720 Elf32_Half compat_class; // Compatibility of archs at VM's sense
1721 char elf_class; // 32 or 64 bit
1722 char endianess; // MSB or LSB
1723 char* name; // String representation
1724 } arch_t;
1725
1726 #ifndef EM_486
1727 #define EM_486 6 /* Intel 80486 */
1728 #endif
1729
1730 static const arch_t arch_array[]={
1731 {EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
1732 {EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
1733 {EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"},
1734 {EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"},
1735 {EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
1736 {EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
1737 {EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"},
1738 {EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"},
1739 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"}
1740 };
1741
1742 #if (defined IA32)
1743 static Elf32_Half running_arch_code=EM_386;
1744 #elif (defined AMD64)
1745 static Elf32_Half running_arch_code=EM_X86_64;
1746 #elif (defined IA64)
1747 static Elf32_Half running_arch_code=EM_IA_64;
1748 #elif (defined __sparc) && (defined _LP64)
1749 static Elf32_Half running_arch_code=EM_SPARCV9;
1750 #elif (defined __sparc) && (!defined _LP64)
1751 static Elf32_Half running_arch_code=EM_SPARC;
1752 #elif (defined __powerpc64__)
1753 static Elf32_Half running_arch_code=EM_PPC64;
1754 #elif (defined __powerpc__)
1755 static Elf32_Half running_arch_code=EM_PPC;
1756 #else
1757 #error Method os::dll_load requires that one of following is defined:\
1758 IA32, AMD64, IA64, __sparc, __powerpc__
1759 #endif
1760
1761 // Identify compatability class for VM's architecture and library's architecture
1762 // Obtain string descriptions for architectures
1763
1764 arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL};
1765 int running_arch_index=-1;
1766
1767 for (unsigned int i=0 ; i < ARRAY_SIZE(arch_array) ; i++ ) {
1768 if (running_arch_code == arch_array[i].code) {
1769 running_arch_index = i;
1770 }
1771 if (lib_arch.code == arch_array[i].code) {
1772 lib_arch.compat_class = arch_array[i].compat_class;
1773 lib_arch.name = arch_array[i].name;
1774 }
1775 }
1776
1777 assert(running_arch_index != -1,
1778 "Didn't find running architecture code (running_arch_code) in arch_array");
1779 if (running_arch_index == -1) {
1780 // Even though running architecture detection failed
1781 // we may still continue with reporting dlerror() message
1782 return NULL;
1783 }
1784
1785 if (lib_arch.endianess != arch_array[running_arch_index].endianess) {
1786 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)");
1787 return NULL;
1788 }
1789
1790 if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) {
1791 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)");
1792 return NULL;
1793 }
1794
1795 if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) {
1796 if ( lib_arch.name!=NULL ) {
1797 ::snprintf(diag_msg_buf, diag_msg_max_length-1,
1798 " (Possible cause: can't load %s-bit .so on a %s-bit platform)",
1799 lib_arch.name, arch_array[running_arch_index].name);
1800 } else {
1801 ::snprintf(diag_msg_buf, diag_msg_max_length-1,
1802 " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)",
1803 lib_arch.code,
1804 arch_array[running_arch_index].name);
1805 }
1806 }
1807
1808 return NULL;
1809 }
1810
1811 /*
1812 * glibc-2.0 libdl is not MT safe. If you are building with any glibc,
1813 * chances are you might want to run the generated bits against glibc-2.0
1814 * libdl.so, so always use locking for any version of glibc.
1815 */
1816 void* os::dll_lookup(void* handle, const char* name) {
1817 pthread_mutex_lock(&dl_mutex);
1818 void* res = dlsym(handle, name);
1819 pthread_mutex_unlock(&dl_mutex);
1820 return res;
1821 }
1822
1823
1824 bool _print_ascii_file(const char* filename, outputStream* st) {
1825 int fd = open(filename, O_RDONLY);
1826 if (fd == -1) {
1827 return false;
1828 }
1829
1830 char buf[32];
1831 int bytes;
1832 while ((bytes = read(fd, buf, sizeof(buf))) > 0) {
1833 st->print_raw(buf, bytes);
1834 }
1835
1836 close(fd);
1837
1838 return true;
1839 }
1840
1841 void os::print_dll_info(outputStream *st) {
1842 st->print_cr("Dynamic libraries:");
1843
1844 char fname[32];
1845 pid_t pid = os::Linux::gettid();
1846
1847 jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid);
1848
1849 if (!_print_ascii_file(fname, st)) {
1850 st->print("Can not get library information for pid = %d\n", pid);
1851 }
1852 }
1853
1854
1855 void os::print_os_info(outputStream* st) {
1856 st->print("OS:");
1857
1858 // Try to identify popular distros.
1859 // Most Linux distributions have /etc/XXX-release file, which contains
1860 // the OS version string. Some have more than one /etc/XXX-release file
1861 // (e.g. Mandrake has both /etc/mandrake-release and /etc/redhat-release.),
1862 // so the order is important.
1863 if (!_print_ascii_file("/etc/mandrake-release", st) &&
1864 !_print_ascii_file("/etc/sun-release", st) &&
1865 !_print_ascii_file("/etc/redhat-release", st) &&
1866 !_print_ascii_file("/etc/SuSE-release", st) &&
1867 !_print_ascii_file("/etc/turbolinux-release", st) &&
1868 !_print_ascii_file("/etc/gentoo-release", st) &&
1869 !_print_ascii_file("/etc/debian_version", st)) {
1870 st->print("Linux");
1871 }
1872 st->cr();
1873
1874 // kernel
1875 st->print("uname:");
1876 struct utsname name;
1877 uname(&name);
1878 st->print(name.sysname); st->print(" ");
1879 st->print(name.release); st->print(" ");
1880 st->print(name.version); st->print(" ");
1881 st->print(name.machine);
1882 st->cr();
1883
1884 // Print warning if unsafe chroot environment detected
1885 if (unsafe_chroot_detected) {
1886 st->print("WARNING!! ");
1887 st->print_cr(unstable_chroot_error);
1888 }
1889
1890 // libc, pthread
1891 st->print("libc:");
1892 st->print(os::Linux::glibc_version()); st->print(" ");
1893 st->print(os::Linux::libpthread_version()); st->print(" ");
1894 if (os::Linux::is_LinuxThreads()) {
1895 st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed");
1896 }
1897 st->cr();
1898
1899 // rlimit
1900 st->print("rlimit:");
1901 struct rlimit rlim;
1902
1903 st->print(" STACK ");
1904 getrlimit(RLIMIT_STACK, &rlim);
1905 if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity");
1906 else st->print("%uk", rlim.rlim_cur >> 10);
1907
1908 st->print(", CORE ");
1909 getrlimit(RLIMIT_CORE, &rlim);
1910 if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity");
1911 else st->print("%uk", rlim.rlim_cur >> 10);
1912
1913 st->print(", NPROC ");
1914 getrlimit(RLIMIT_NPROC, &rlim);
1915 if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity");
1916 else st->print("%d", rlim.rlim_cur);
1917
1918 st->print(", NOFILE ");
1919 getrlimit(RLIMIT_NOFILE, &rlim);
1920 if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity");
1921 else st->print("%d", rlim.rlim_cur);
1922
1923 st->print(", AS ");
1924 getrlimit(RLIMIT_AS, &rlim);
1925 if (rlim.rlim_cur == RLIM_INFINITY) st->print("infinity");
1926 else st->print("%uk", rlim.rlim_cur >> 10);
1927 st->cr();
1928
1929 // load average
1930 st->print("load average:");
1931 double loadavg[3];
1932 os::loadavg(loadavg, 3);
1933 st->print("%0.02f %0.02f %0.02f", loadavg[0], loadavg[1], loadavg[2]);
1934 st->cr();
1935 }
1936
1937 void os::print_memory_info(outputStream* st) {
1938
1939 st->print("Memory:");
1940 st->print(" %dk page", os::vm_page_size()>>10);
1941
1942 // values in struct sysinfo are "unsigned long"
1943 struct sysinfo si;
1944 sysinfo(&si);
1945
1946 st->print(", physical " UINT64_FORMAT "k",
1947 os::physical_memory() >> 10);
1948 st->print("(" UINT64_FORMAT "k free)",
1949 os::available_memory() >> 10);
1950 st->print(", swap " UINT64_FORMAT "k",
1951 ((jlong)si.totalswap * si.mem_unit) >> 10);
1952 st->print("(" UINT64_FORMAT "k free)",
1953 ((jlong)si.freeswap * si.mem_unit) >> 10);
1954 st->cr();
1955 }
1956
1957 // Taken from /usr/include/bits/siginfo.h Supposed to be architecture specific
1958 // but they're the same for all the linux arch that we support
1959 // and they're the same for solaris but there's no common place to put this.
1960 const char *ill_names[] = { "ILL0", "ILL_ILLOPC", "ILL_ILLOPN", "ILL_ILLADR",
1961 "ILL_ILLTRP", "ILL_PRVOPC", "ILL_PRVREG",
1962 "ILL_COPROC", "ILL_BADSTK" };
1963
1964 const char *fpe_names[] = { "FPE0", "FPE_INTDIV", "FPE_INTOVF", "FPE_FLTDIV",
1965 "FPE_FLTOVF", "FPE_FLTUND", "FPE_FLTRES",
1966 "FPE_FLTINV", "FPE_FLTSUB", "FPE_FLTDEN" };
1967
1968 const char *segv_names[] = { "SEGV0", "SEGV_MAPERR", "SEGV_ACCERR" };
1969
1970 const char *bus_names[] = { "BUS0", "BUS_ADRALN", "BUS_ADRERR", "BUS_OBJERR" };
1971
1972 void os::print_siginfo(outputStream* st, void* siginfo) {
1973 st->print("siginfo:");
1974
1975 const int buflen = 100;
1976 char buf[buflen];
1977 siginfo_t *si = (siginfo_t*)siginfo;
1978 st->print("si_signo=%s: ", os::exception_name(si->si_signo, buf, buflen));
1979 if (si->si_errno != 0 && strerror_r(si->si_errno, buf, buflen) == 0) {
1980 st->print("si_errno=%s", buf);
1981 } else {
1982 st->print("si_errno=%d", si->si_errno);
1983 }
1984 const int c = si->si_code;
1985 assert(c > 0, "unexpected si_code");
1986 switch (si->si_signo) {
1987 case SIGILL:
1988 st->print(", si_code=%d (%s)", c, c > 8 ? "" : ill_names[c]);
1989 st->print(", si_addr=" PTR_FORMAT, si->si_addr);
1990 break;
1991 case SIGFPE:
1992 st->print(", si_code=%d (%s)", c, c > 9 ? "" : fpe_names[c]);
1993 st->print(", si_addr=" PTR_FORMAT, si->si_addr);
1994 break;
1995 case SIGSEGV:
1996 st->print(", si_code=%d (%s)", c, c > 2 ? "" : segv_names[c]);
1997 st->print(", si_addr=" PTR_FORMAT, si->si_addr);
1998 break;
1999 case SIGBUS:
2000 st->print(", si_code=%d (%s)", c, c > 3 ? "" : bus_names[c]);
2001 st->print(", si_addr=" PTR_FORMAT, si->si_addr);
2002 break;
2003 default:
2004 st->print(", si_code=%d", si->si_code);
2005 // no si_addr
2006 }
2007
2008 if ((si->si_signo == SIGBUS || si->si_signo == SIGSEGV) &&
2009 UseSharedSpaces) {
2010 FileMapInfo* mapinfo = FileMapInfo::current_info();
2011 if (mapinfo->is_in_shared_space(si->si_addr)) {
2012 st->print("\n\nError accessing class data sharing archive." \
2013 " Mapped file inaccessible during execution, " \
2014 " possible disk/network problem.");
2015 }
2016 }
2017 st->cr();
2018 }
2019
2020
2021 static void print_signal_handler(outputStream* st, int sig,
2022 char* buf, size_t buflen);
2023
2024 void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) {
2025 st->print_cr("Signal Handlers:");
2026 print_signal_handler(st, SIGSEGV, buf, buflen);
2027 print_signal_handler(st, SIGBUS , buf, buflen);
2028 print_signal_handler(st, SIGFPE , buf, buflen);
2029 print_signal_handler(st, SIGPIPE, buf, buflen);
2030 print_signal_handler(st, SIGXFSZ, buf, buflen);
2031 print_signal_handler(st, SIGILL , buf, buflen);
2032 print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen);
2033 print_signal_handler(st, SR_signum, buf, buflen);
2034 print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen);
2035 print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen);
2036 print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen);
2037 print_signal_handler(st, BREAK_SIGNAL, buf, buflen);
2038 }
2039
2040 static char saved_jvm_path[MAXPATHLEN] = {0};
2041
2042 // Find the full path to the current module, libjvm.so or libjvm_g.so
2043 void os::jvm_path(char *buf, jint len) {
2044 // Error checking.
2045 if (len < MAXPATHLEN) {
2046 assert(false, "must use a large-enough buffer");
2047 buf[0] = '\0';
2048 return;
2049 }
2050 // Lazy resolve the path to current module.
2051 if (saved_jvm_path[0] != 0) {
2052 strcpy(buf, saved_jvm_path);
2053 return;
2054 }
2055
2056 char dli_fname[MAXPATHLEN];
2057 bool ret = dll_address_to_library_name(
2058 CAST_FROM_FN_PTR(address, os::jvm_path),
2059 dli_fname, sizeof(dli_fname), NULL);
2060 assert(ret != 0, "cannot locate libjvm");
2061 realpath(dli_fname, buf);
2062
2063 if (strcmp(Arguments::sun_java_launcher(), "gamma") == 0) {
2064 // Support for the gamma launcher. Typical value for buf is
2065 // "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so". If "/jre/lib/" appears at
2066 // the right place in the string, then assume we are installed in a JDK and
2067 // we're done. Otherwise, check for a JAVA_HOME environment variable and fix
2068 // up the path so it looks like libjvm.so is installed there (append a
2069 // fake suffix hotspot/libjvm.so).
2070 const char *p = buf + strlen(buf) - 1;
2071 for (int count = 0; p > buf && count < 5; ++count) {
2072 for (--p; p > buf && *p != '/'; --p)
2073 /* empty */ ;
2074 }
2075
2076 if (strncmp(p, "/jre/lib/", 9) != 0) {
2077 // Look for JAVA_HOME in the environment.
2078 char* java_home_var = ::getenv("JAVA_HOME");
2079 if (java_home_var != NULL && java_home_var[0] != 0) {
2080 // Check the current module name "libjvm.so" or "libjvm_g.so".
2081 p = strrchr(buf, '/');
2082 assert(strstr(p, "/libjvm") == p, "invalid library name");
2083 p = strstr(p, "_g") ? "_g" : "";
2084
2085 realpath(java_home_var, buf);
2086 sprintf(buf + strlen(buf), "/jre/lib/%s", cpu_arch);
2087 if (0 == access(buf, F_OK)) {
2088 // Use current module name "libjvm[_g].so" instead of
2089 // "libjvm"debug_only("_g")".so" since for fastdebug version
2090 // we should have "libjvm.so" but debug_only("_g") adds "_g"!
2091 // It is used when we are choosing the HPI library's name
2092 // "libhpi[_g].so" in hpi::initialize_get_interface().
2093 sprintf(buf + strlen(buf), "/hotspot/libjvm%s.so", p);
2094 } else {
2095 // Go back to path of .so
2096 realpath(dli_fname, buf);
2097 }
2098 }
2099 }
2100 }
2101
2102 strcpy(saved_jvm_path, buf);
2103 }
2104
2105 void os::print_jni_name_prefix_on(outputStream* st, int args_size) {
2106 // no prefix required, not even "_"
2107 }
2108
2109 void os::print_jni_name_suffix_on(outputStream* st, int args_size) {
2110 // no suffix required
2111 }
2112
2113 ////////////////////////////////////////////////////////////////////////////////
2114 // sun.misc.Signal support
2115
2116 static volatile jint sigint_count = 0;
2117
2118 static void
2119 UserHandler(int sig, void *siginfo, void *context) {
2120 // 4511530 - sem_post is serialized and handled by the manager thread. When
2121 // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We
2122 // don't want to flood the manager thread with sem_post requests.
2123 if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1)
2124 return;
2125
2126 // Ctrl-C is pressed during error reporting, likely because the error
2127 // handler fails to abort. Let VM die immediately.
2128 if (sig == SIGINT && is_error_reported()) {
2129 os::die();
2130 }
2131
2132 os::signal_notify(sig);
2133 }
2134
2135 void* os::user_handler() {
2136 return CAST_FROM_FN_PTR(void*, UserHandler);
2137 }
2138
2139 extern "C" {
2140 typedef void (*sa_handler_t)(int);
2141 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *);
2142 }
2143
2144 void* os::signal(int signal_number, void* handler) {
2145 struct sigaction sigAct, oldSigAct;
2146
2147 sigfillset(&(sigAct.sa_mask));
2148 sigAct.sa_flags = SA_RESTART|SA_SIGINFO;
2149 sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler);
2150
2151 if (sigaction(signal_number, &sigAct, &oldSigAct)) {
2152 // -1 means registration failed
2153 return (void *)-1;
2154 }
2155
2156 return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler);
2157 }
2158
2159 void os::signal_raise(int signal_number) {
2160 ::raise(signal_number);
2161 }
2162
2163 /*
2164 * The following code is moved from os.cpp for making this
2165 * code platform specific, which it is by its very nature.
2166 */
2167
2168 // Will be modified when max signal is changed to be dynamic
2169 int os::sigexitnum_pd() {
2170 return NSIG;
2171 }
2172
2173 // a counter for each possible signal value
2174 static volatile jint pending_signals[NSIG+1] = { 0 };
2175
2176 // Linux(POSIX) specific hand shaking semaphore.
2177 static sem_t sig_sem;
2178
2179 void os::signal_init_pd() {
2180 // Initialize signal structures
2181 ::memset((void*)pending_signals, 0, sizeof(pending_signals));
2182
2183 // Initialize signal semaphore
2184 ::sem_init(&sig_sem, 0, 0);
2185 }
2186
2187 void os::signal_notify(int sig) {
2188 Atomic::inc(&pending_signals[sig]);
2189 ::sem_post(&sig_sem);
2190 }
2191
2192 static int check_pending_signals(bool wait) {
2193 Atomic::store(0, &sigint_count);
2194 for (;;) {
2195 for (int i = 0; i < NSIG + 1; i++) {
2196 jint n = pending_signals[i];
2197 if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) {
2198 return i;
2199 }
2200 }
2201 if (!wait) {
2202 return -1;
2203 }
2204 JavaThread *thread = JavaThread::current();
2205 ThreadBlockInVM tbivm(thread);
2206
2207 bool threadIsSuspended;
2208 do {
2209 thread->set_suspend_equivalent();
2210 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
2211 ::sem_wait(&sig_sem);
2212
2213 // were we externally suspended while we were waiting?
2214 threadIsSuspended = thread->handle_special_suspend_equivalent_condition();
2215 if (threadIsSuspended) {
2216 //
2217 // The semaphore has been incremented, but while we were waiting
2218 // another thread suspended us. We don't want to continue running
2219 // while suspended because that would surprise the thread that
2220 // suspended us.
2221 //
2222 ::sem_post(&sig_sem);
2223
2224 thread->java_suspend_self();
2225 }
2226 } while (threadIsSuspended);
2227 }
2228 }
2229
2230 int os::signal_lookup() {
2231 return check_pending_signals(false);
2232 }
2233
2234 int os::signal_wait() {
2235 return check_pending_signals(true);
2236 }
2237
2238 ////////////////////////////////////////////////////////////////////////////////
2239 // Virtual Memory
2240
2241 int os::vm_page_size() {
2242 // Seems redundant as all get out
2243 assert(os::Linux::page_size() != -1, "must call os::init");
2244 return os::Linux::page_size();
2245 }
2246
2247 // Solaris allocates memory by pages.
2248 int os::vm_allocation_granularity() {
2249 assert(os::Linux::page_size() != -1, "must call os::init");
2250 return os::Linux::page_size();
2251 }
2252
2253 // Rationale behind this function:
2254 // current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable
2255 // mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get
2256 // samples for JITted code. Here we create private executable mapping over the code cache
2257 // and then we can use standard (well, almost, as mapping can change) way to provide
2258 // info for the reporting script by storing timestamp and location of symbol
2259 void linux_wrap_code(char* base, size_t size) {
2260 static volatile jint cnt = 0;
2261
2262 if (!UseOprofile) {
2263 return;
2264 }
2265
2266 char buf[40];
2267 int num = Atomic::add(1, &cnt);
2268
2269 sprintf(buf, "/tmp/hs-vm-%d-%d", os::current_process_id(), num);
2270 unlink(buf);
2271
2272 int fd = open(buf, O_CREAT | O_RDWR, S_IRWXU);
2273
2274 if (fd != -1) {
2275 off_t rv = lseek(fd, size-2, SEEK_SET);
2276 if (rv != (off_t)-1) {
2277 if (write(fd, "", 1) == 1) {
2278 mmap(base, size,
2279 PROT_READ|PROT_WRITE|PROT_EXEC,
2280 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0);
2281 }
2282 }
2283 close(fd);
2284 unlink(buf);
2285 }
2286 }
2287
2288 // NOTE: Linux kernel does not really reserve the pages for us.
2289 // All it does is to check if there are enough free pages
2290 // left at the time of mmap(). This could be a potential
2291 // problem.
2292 bool os::commit_memory(char* addr, size_t size) {
2293 uintptr_t res = (uintptr_t) ::mmap(addr, size,
2294 PROT_READ|PROT_WRITE|PROT_EXEC,
2295 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0);
2296 return res != (uintptr_t) MAP_FAILED;
2297 }
2298
2299 bool os::commit_memory(char* addr, size_t size, size_t alignment_hint) {
2300 return commit_memory(addr, size);
2301 }
2302
2303 void os::realign_memory(char *addr, size_t bytes, size_t alignment_hint) { }
2304
2305 void os::free_memory(char *addr, size_t bytes) {
2306 uncommit_memory(addr, bytes);
2307 }
2308
2309 void os::numa_make_global(char *addr, size_t bytes) {
2310 Linux::numa_interleave_memory(addr, bytes);
2311 }
2312
2313 void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) {
2314 Linux::numa_tonode_memory(addr, bytes, lgrp_hint);
2315 }
2316
2317 bool os::numa_topology_changed() { return false; }
2318
2319 size_t os::numa_get_groups_num() {
2320 int max_node = Linux::numa_max_node();
2321 return max_node > 0 ? max_node + 1 : 1;
2322 }
2323
2324 int os::numa_get_group_id() {
2325 int cpu_id = Linux::sched_getcpu();
2326 if (cpu_id != -1) {
2327 int lgrp_id = Linux::get_node_by_cpu(cpu_id);
2328 if (lgrp_id != -1) {
2329 return lgrp_id;
2330 }
2331 }
2332 return 0;
2333 }
2334
2335 size_t os::numa_get_leaf_groups(int *ids, size_t size) {
2336 for (size_t i = 0; i < size; i++) {
2337 ids[i] = i;
2338 }
2339 return size;
2340 }
2341
2342 bool os::get_page_info(char *start, page_info* info) {
2343 return false;
2344 }
2345
2346 char *os::scan_pages(char *start, char* end, page_info* page_expected, page_info* page_found) {
2347 return end;
2348 }
2349
2350 extern "C" void numa_warn(int number, char *where, ...) { }
2351 extern "C" void numa_error(char *where) { }
2352
2353 bool os::Linux::libnuma_init() {
2354 // sched_getcpu() should be in libc.
2355 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t,
2356 dlsym(RTLD_DEFAULT, "sched_getcpu")));
2357
2358 if (sched_getcpu() != -1) { // Does it work?
2359 void *handle = dlopen("libnuma.so.1", RTLD_LAZY);
2360 if (handle != NULL) {
2361 set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t,
2362 dlsym(handle, "numa_node_to_cpus")));
2363 set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t,
2364 dlsym(handle, "numa_max_node")));
2365 set_numa_available(CAST_TO_FN_PTR(numa_available_func_t,
2366 dlsym(handle, "numa_available")));
2367 set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t,
2368 dlsym(handle, "numa_tonode_memory")));
2369 set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t,
2370 dlsym(handle, "numa_interleave_memory")));
2371
2372
2373 if (numa_available() != -1) {
2374 set_numa_all_nodes((unsigned long*)dlsym(handle, "numa_all_nodes"));
2375 // Create a cpu -> node mapping
2376 _cpu_to_node = new (ResourceObj::C_HEAP) GrowableArray<int>(0, true);
2377 rebuild_cpu_to_node_map();
2378 return true;
2379 }
2380 }
2381 }
2382 return false;
2383 }
2384
2385 // rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id.
2386 // The table is later used in get_node_by_cpu().
2387 void os::Linux::rebuild_cpu_to_node_map() {
2388 const size_t NCPUS = 32768; // Since the buffer size computation is very obscure
2389 // in libnuma (possible values are starting from 16,
2390 // and continuing up with every other power of 2, but less
2391 // than the maximum number of CPUs supported by kernel), and
2392 // is a subject to change (in libnuma version 2 the requirements
2393 // are more reasonable) we'll just hardcode the number they use
2394 // in the library.
2395 const size_t BitsPerCLong = sizeof(long) * CHAR_BIT;
2396
2397 size_t cpu_num = os::active_processor_count();
2398 size_t cpu_map_size = NCPUS / BitsPerCLong;
2399 size_t cpu_map_valid_size =
2400 MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size);
2401
2402 cpu_to_node()->clear();
2403 cpu_to_node()->at_grow(cpu_num - 1);
2404 size_t node_num = numa_get_groups_num();
2405
2406 unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size);
2407 for (size_t i = 0; i < node_num; i++) {
2408 if (numa_node_to_cpus(i, cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) {
2409 for (size_t j = 0; j < cpu_map_valid_size; j++) {
2410 if (cpu_map[j] != 0) {
2411 for (size_t k = 0; k < BitsPerCLong; k++) {
2412 if (cpu_map[j] & (1UL << k)) {
2413 cpu_to_node()->at_put(j * BitsPerCLong + k, i);
2414 }
2415 }
2416 }
2417 }
2418 }
2419 }
2420 FREE_C_HEAP_ARRAY(unsigned long, cpu_map);
2421 }
2422
2423 int os::Linux::get_node_by_cpu(int cpu_id) {
2424 if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) {
2425 return cpu_to_node()->at(cpu_id);
2426 }
2427 return -1;
2428 }
2429
2430 GrowableArray<int>* os::Linux::_cpu_to_node;
2431 os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu;
2432 os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus;
2433 os::Linux::numa_max_node_func_t os::Linux::_numa_max_node;
2434 os::Linux::numa_available_func_t os::Linux::_numa_available;
2435 os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory;
2436 os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory;
2437 unsigned long* os::Linux::_numa_all_nodes;
2438
2439 bool os::uncommit_memory(char* addr, size_t size) {
2440 return ::mmap(addr, size,
2441 PROT_READ|PROT_WRITE|PROT_EXEC,
2442 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0)
2443 != MAP_FAILED;
2444 }
2445
2446 static address _highest_vm_reserved_address = NULL;
2447
2448 // If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory
2449 // at 'requested_addr'. If there are existing memory mappings at the same
2450 // location, however, they will be overwritten. If 'fixed' is false,
2451 // 'requested_addr' is only treated as a hint, the return value may or
2452 // may not start from the requested address. Unlike Linux mmap(), this
2453 // function returns NULL to indicate failure.
2454 static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) {
2455 char * addr;
2456 int flags;
2457
2458 flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS;
2459 if (fixed) {
2460 assert((uintptr_t)requested_addr % os::Linux::page_size() == 0, "unaligned address");
2461 flags |= MAP_FIXED;
2462 }
2463
2464 addr = (char*)::mmap(requested_addr, bytes, PROT_READ|PROT_WRITE|PROT_EXEC,
2465 flags, -1, 0);
2466
2467 if (addr != MAP_FAILED) {
2468 // anon_mmap() should only get called during VM initialization,
2469 // don't need lock (actually we can skip locking even it can be called
2470 // from multiple threads, because _highest_vm_reserved_address is just a
2471 // hint about the upper limit of non-stack memory regions.)
2472 if ((address)addr + bytes > _highest_vm_reserved_address) {
2473 _highest_vm_reserved_address = (address)addr + bytes;
2474 }
2475 }
2476
2477 return addr == MAP_FAILED ? NULL : addr;
2478 }
2479
2480 // Don't update _highest_vm_reserved_address, because there might be memory
2481 // regions above addr + size. If so, releasing a memory region only creates
2482 // a hole in the address space, it doesn't help prevent heap-stack collision.
2483 //
2484 static int anon_munmap(char * addr, size_t size) {
2485 return ::munmap(addr, size) == 0;
2486 }
2487
2488 char* os::reserve_memory(size_t bytes, char* requested_addr,
2489 size_t alignment_hint) {
2490 return anon_mmap(requested_addr, bytes, (requested_addr != NULL));
2491 }
2492
2493 bool os::release_memory(char* addr, size_t size) {
2494 return anon_munmap(addr, size);
2495 }
2496
2497 static address highest_vm_reserved_address() {
2498 return _highest_vm_reserved_address;
2499 }
2500
2501 static bool linux_mprotect(char* addr, size_t size, int prot) {
2502 // Linux wants the mprotect address argument to be page aligned.
2503 char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::page_size());
2504
2505 // According to SUSv3, mprotect() should only be used with mappings
2506 // established by mmap(), and mmap() always maps whole pages. Unaligned
2507 // 'addr' likely indicates problem in the VM (e.g. trying to change
2508 // protection of malloc'ed or statically allocated memory). Check the
2509 // caller if you hit this assert.
2510 assert(addr == bottom, "sanity check");
2511
2512 size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Linux::page_size());
2513 return ::mprotect(bottom, size, prot) == 0;
2514 }
2515
2516 // Set protections specified
2517 bool os::protect_memory(char* addr, size_t bytes, ProtType prot,
2518 bool is_committed) {
2519 unsigned int p = 0;
2520 switch (prot) {
2521 case MEM_PROT_NONE: p = PROT_NONE; break;
2522 case MEM_PROT_READ: p = PROT_READ; break;
2523 case MEM_PROT_RW: p = PROT_READ|PROT_WRITE; break;
2524 case MEM_PROT_RWX: p = PROT_READ|PROT_WRITE|PROT_EXEC; break;
2525 default:
2526 ShouldNotReachHere();
2527 }
2528 // is_committed is unused.
2529 return linux_mprotect(addr, bytes, p);
2530 }
2531
2532 bool os::guard_memory(char* addr, size_t size) {
2533 return linux_mprotect(addr, size, PROT_NONE);
2534 }
2535
2536 bool os::unguard_memory(char* addr, size_t size) {
2537 return linux_mprotect(addr, size, PROT_READ|PROT_WRITE);
2538 }
2539
2540 // Large page support
2541
2542 static size_t _large_page_size = 0;
2543
2544 bool os::large_page_init() {
2545 if (!UseLargePages) return false;
2546
2547 if (LargePageSizeInBytes) {
2548 _large_page_size = LargePageSizeInBytes;
2549 } else {
2550 // large_page_size on Linux is used to round up heap size. x86 uses either
2551 // 2M or 4M page, depending on whether PAE (Physical Address Extensions)
2552 // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use
2553 // page as large as 256M.
2554 //
2555 // Here we try to figure out page size by parsing /proc/meminfo and looking
2556 // for a line with the following format:
2557 // Hugepagesize: 2048 kB
2558 //
2559 // If we can't determine the value (e.g. /proc is not mounted, or the text
2560 // format has been changed), we'll use the largest page size supported by
2561 // the processor.
2562
2563 _large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M);
2564
2565 FILE *fp = fopen("/proc/meminfo", "r");
2566 if (fp) {
2567 while (!feof(fp)) {
2568 int x = 0;
2569 char buf[16];
2570 if (fscanf(fp, "Hugepagesize: %d", &x) == 1) {
2571 if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) {
2572 _large_page_size = x * K;
2573 break;
2574 }
2575 } else {
2576 // skip to next line
2577 for (;;) {
2578 int ch = fgetc(fp);
2579 if (ch == EOF || ch == (int)'\n') break;
2580 }
2581 }
2582 }
2583 fclose(fp);
2584 }
2585 }
2586
2587 const size_t default_page_size = (size_t)Linux::page_size();
2588 if (_large_page_size > default_page_size) {
2589 _page_sizes[0] = _large_page_size;
2590 _page_sizes[1] = default_page_size;
2591 _page_sizes[2] = 0;
2592 }
2593
2594 // Large page support is available on 2.6 or newer kernel, some vendors
2595 // (e.g. Redhat) have backported it to their 2.4 based distributions.
2596 // We optimistically assume the support is available. If later it turns out
2597 // not true, VM will automatically switch to use regular page size.
2598 return true;
2599 }
2600
2601 #ifndef SHM_HUGETLB
2602 #define SHM_HUGETLB 04000
2603 #endif
2604
2605 char* os::reserve_memory_special(size_t bytes) {
2606 assert(UseLargePages, "only for large pages");
2607
2608 key_t key = IPC_PRIVATE;
2609 char *addr;
2610
2611 bool warn_on_failure = UseLargePages &&
2612 (!FLAG_IS_DEFAULT(UseLargePages) ||
2613 !FLAG_IS_DEFAULT(LargePageSizeInBytes)
2614 );
2615 char msg[128];
2616
2617 // Create a large shared memory region to attach to based on size.
2618 // Currently, size is the total size of the heap
2619 int shmid = shmget(key, bytes, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W);
2620 if (shmid == -1) {
2621 // Possible reasons for shmget failure:
2622 // 1. shmmax is too small for Java heap.
2623 // > check shmmax value: cat /proc/sys/kernel/shmmax
2624 // > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax
2625 // 2. not enough large page memory.
2626 // > check available large pages: cat /proc/meminfo
2627 // > increase amount of large pages:
2628 // echo new_value > /proc/sys/vm/nr_hugepages
2629 // Note 1: different Linux may use different name for this property,
2630 // e.g. on Redhat AS-3 it is "hugetlb_pool".
2631 // Note 2: it's possible there's enough physical memory available but
2632 // they are so fragmented after a long run that they can't
2633 // coalesce into large pages. Try to reserve large pages when
2634 // the system is still "fresh".
2635 if (warn_on_failure) {
2636 jio_snprintf(msg, sizeof(msg), "Failed to reserve shared memory (errno = %d).", errno);
2637 warning(msg);
2638 }
2639 return NULL;
2640 }
2641
2642 // attach to the region
2643 addr = (char*)shmat(shmid, NULL, 0);
2644 int err = errno;
2645
2646 // Remove shmid. If shmat() is successful, the actual shared memory segment
2647 // will be deleted when it's detached by shmdt() or when the process
2648 // terminates. If shmat() is not successful this will remove the shared
2649 // segment immediately.
2650 shmctl(shmid, IPC_RMID, NULL);
2651
2652 if ((intptr_t)addr == -1) {
2653 if (warn_on_failure) {
2654 jio_snprintf(msg, sizeof(msg), "Failed to attach shared memory (errno = %d).", err);
2655 warning(msg);
2656 }
2657 return NULL;
2658 }
2659
2660 return addr;
2661 }
2662
2663 bool os::release_memory_special(char* base, size_t bytes) {
2664 // detaching the SHM segment will also delete it, see reserve_memory_special()
2665 int rslt = shmdt(base);
2666 return rslt == 0;
2667 }
2668
2669 size_t os::large_page_size() {
2670 return _large_page_size;
2671 }
2672
2673 // Linux does not support anonymous mmap with large page memory. The only way
2674 // to reserve large page memory without file backing is through SysV shared
2675 // memory API. The entire memory region is committed and pinned upfront.
2676 // Hopefully this will change in the future...
2677 bool os::can_commit_large_page_memory() {
2678 return false;
2679 }
2680
2681 bool os::can_execute_large_page_memory() {
2682 return false;
2683 }
2684
2685 // Reserve memory at an arbitrary address, only if that area is
2686 // available (and not reserved for something else).
2687
2688 char* os::attempt_reserve_memory_at(size_t bytes, char* requested_addr) {
2689 const int max_tries = 10;
2690 char* base[max_tries];
2691 size_t size[max_tries];
2692 const size_t gap = 0x000000;
2693
2694 // Assert only that the size is a multiple of the page size, since
2695 // that's all that mmap requires, and since that's all we really know
2696 // about at this low abstraction level. If we need higher alignment,
2697 // we can either pass an alignment to this method or verify alignment
2698 // in one of the methods further up the call chain. See bug 5044738.
2699 assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block");
2700
2701 // Repeatedly allocate blocks until the block is allocated at the
2702 // right spot. Give up after max_tries. Note that reserve_memory() will
2703 // automatically update _highest_vm_reserved_address if the call is
2704 // successful. The variable tracks the highest memory address every reserved
2705 // by JVM. It is used to detect heap-stack collision if running with
2706 // fixed-stack LinuxThreads. Because here we may attempt to reserve more
2707 // space than needed, it could confuse the collision detecting code. To
2708 // solve the problem, save current _highest_vm_reserved_address and
2709 // calculate the correct value before return.
2710 address old_highest = _highest_vm_reserved_address;
2711
2712 // Linux mmap allows caller to pass an address as hint; give it a try first,
2713 // if kernel honors the hint then we can return immediately.
2714 char * addr = anon_mmap(requested_addr, bytes, false);
2715 if (addr == requested_addr) {
2716 return requested_addr;
2717 }
2718
2719 if (addr != NULL) {
2720 // mmap() is successful but it fails to reserve at the requested address
2721 anon_munmap(addr, bytes);
2722 }
2723
2724 int i;
2725 for (i = 0; i < max_tries; ++i) {
2726 base[i] = reserve_memory(bytes);
2727
2728 if (base[i] != NULL) {
2729 // Is this the block we wanted?
2730 if (base[i] == requested_addr) {
2731 size[i] = bytes;
2732 break;
2733 }
2734
2735 // Does this overlap the block we wanted? Give back the overlapped
2736 // parts and try again.
2737
2738 size_t top_overlap = requested_addr + (bytes + gap) - base[i];
2739 if (top_overlap >= 0 && top_overlap < bytes) {
2740 unmap_memory(base[i], top_overlap);
2741 base[i] += top_overlap;
2742 size[i] = bytes - top_overlap;
2743 } else {
2744 size_t bottom_overlap = base[i] + bytes - requested_addr;
2745 if (bottom_overlap >= 0 && bottom_overlap < bytes) {
2746 unmap_memory(requested_addr, bottom_overlap);
2747 size[i] = bytes - bottom_overlap;
2748 } else {
2749 size[i] = bytes;
2750 }
2751 }
2752 }
2753 }
2754
2755 // Give back the unused reserved pieces.
2756
2757 for (int j = 0; j < i; ++j) {
2758 if (base[j] != NULL) {
2759 unmap_memory(base[j], size[j]);
2760 }
2761 }
2762
2763 if (i < max_tries) {
2764 _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes);
2765 return requested_addr;
2766 } else {
2767 _highest_vm_reserved_address = old_highest;
2768 return NULL;
2769 }
2770 }
2771
2772 size_t os::read(int fd, void *buf, unsigned int nBytes) {
2773 return ::read(fd, buf, nBytes);
2774 }
2775
2776 // TODO-FIXME: reconcile Solaris' os::sleep with the linux variation.
2777 // Solaris uses poll(), linux uses park().
2778 // Poll() is likely a better choice, assuming that Thread.interrupt()
2779 // generates a SIGUSRx signal. Note that SIGUSR1 can interfere with
2780 // SIGSEGV, see 4355769.
2781
2782 const int NANOSECS_PER_MILLISECS = 1000000;
2783
2784 int os::sleep(Thread* thread, jlong millis, bool interruptible) {
2785 assert(thread == Thread::current(), "thread consistency check");
2786
2787 ParkEvent * const slp = thread->_SleepEvent ;
2788 slp->reset() ;
2789 OrderAccess::fence() ;
2790
2791 if (interruptible) {
2792 jlong prevtime = javaTimeNanos();
2793
2794 for (;;) {
2795 if (os::is_interrupted(thread, true)) {
2796 return OS_INTRPT;
2797 }
2798
2799 jlong newtime = javaTimeNanos();
2800
2801 if (newtime - prevtime < 0) {
2802 // time moving backwards, should only happen if no monotonic clock
2803 // not a guarantee() because JVM should not abort on kernel/glibc bugs
2804 assert(!Linux::supports_monotonic_clock(), "time moving backwards");
2805 } else {
2806 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISECS;
2807 }
2808
2809 if(millis <= 0) {
2810 return OS_OK;
2811 }
2812
2813 prevtime = newtime;
2814
2815 {
2816 assert(thread->is_Java_thread(), "sanity check");
2817 JavaThread *jt = (JavaThread *) thread;
2818 ThreadBlockInVM tbivm(jt);
2819 OSThreadWaitState osts(jt->osthread(), false /* not Object.wait() */);
2820
2821 jt->set_suspend_equivalent();
2822 // cleared by handle_special_suspend_equivalent_condition() or
2823 // java_suspend_self() via check_and_wait_while_suspended()
2824
2825 slp->park(millis);
2826
2827 // were we externally suspended while we were waiting?
2828 jt->check_and_wait_while_suspended();
2829 }
2830 }
2831 } else {
2832 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */);
2833 jlong prevtime = javaTimeNanos();
2834
2835 for (;;) {
2836 // It'd be nice to avoid the back-to-back javaTimeNanos() calls on
2837 // the 1st iteration ...
2838 jlong newtime = javaTimeNanos();
2839
2840 if (newtime - prevtime < 0) {
2841 // time moving backwards, should only happen if no monotonic clock
2842 // not a guarantee() because JVM should not abort on kernel/glibc bugs
2843 assert(!Linux::supports_monotonic_clock(), "time moving backwards");
2844 } else {
2845 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISECS;
2846 }
2847
2848 if(millis <= 0) break ;
2849
2850 prevtime = newtime;
2851 slp->park(millis);
2852 }
2853 return OS_OK ;
2854 }
2855 }
2856
2857 int os::naked_sleep() {
2858 // %% make the sleep time an integer flag. for now use 1 millisec.
2859 return os::sleep(Thread::current(), 1, false);
2860 }
2861
2862 // Sleep forever; naked call to OS-specific sleep; use with CAUTION
2863 void os::infinite_sleep() {
2864 while (true) { // sleep forever ...
2865 ::sleep(100); // ... 100 seconds at a time
2866 }
2867 }
2868
2869 // Used to convert frequent JVM_Yield() to nops
2870 bool os::dont_yield() {
2871 return DontYieldALot;
2872 }
2873
2874 void os::yield() {
2875 sched_yield();
2876 }
2877
2878 os::YieldResult os::NakedYield() { sched_yield(); return os::YIELD_UNKNOWN ;}
2879
2880 void os::yield_all(int attempts) {
2881 // Yields to all threads, including threads with lower priorities
2882 // Threads on Linux are all with same priority. The Solaris style
2883 // os::yield_all() with nanosleep(1ms) is not necessary.
2884 sched_yield();
2885 }
2886
2887 // Called from the tight loops to possibly influence time-sharing heuristics
2888 void os::loop_breaker(int attempts) {
2889 os::yield_all(attempts);
2890 }
2891
2892 ////////////////////////////////////////////////////////////////////////////////
2893 // thread priority support
2894
2895 // Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER
2896 // only supports dynamic priority, static priority must be zero. For real-time
2897 // applications, Linux supports SCHED_RR which allows static priority (1-99).
2898 // However, for large multi-threaded applications, SCHED_RR is not only slower
2899 // than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out
2900 // of 5 runs - Sep 2005).
2901 //
2902 // The following code actually changes the niceness of kernel-thread/LWP. It
2903 // has an assumption that setpriority() only modifies one kernel-thread/LWP,
2904 // not the entire user process, and user level threads are 1:1 mapped to kernel
2905 // threads. It has always been the case, but could change in the future. For
2906 // this reason, the code should not be used as default (ThreadPriorityPolicy=0).
2907 // It is only used when ThreadPriorityPolicy=1 and requires root privilege.
2908
2909 int os::java_to_os_priority[MaxPriority + 1] = {
2910 19, // 0 Entry should never be used
2911
2912 4, // 1 MinPriority
2913 3, // 2
2914 2, // 3
2915
2916 1, // 4
2917 0, // 5 NormPriority
2918 -1, // 6
2919
2920 -2, // 7
2921 -3, // 8
2922 -4, // 9 NearMaxPriority
2923
2924 -5 // 10 MaxPriority
2925 };
2926
2927 static int prio_init() {
2928 if (ThreadPriorityPolicy == 1) {
2929 // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1
2930 // if effective uid is not root. Perhaps, a more elegant way of doing
2931 // this is to test CAP_SYS_NICE capability, but that will require libcap.so
2932 if (geteuid() != 0) {
2933 if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) {
2934 warning("-XX:ThreadPriorityPolicy requires root privilege on Linux");
2935 }
2936 ThreadPriorityPolicy = 0;
2937 }
2938 }
2939 return 0;
2940 }
2941
2942 OSReturn os::set_native_priority(Thread* thread, int newpri) {
2943 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) return OS_OK;
2944
2945 int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri);
2946 return (ret == 0) ? OS_OK : OS_ERR;
2947 }
2948
2949 OSReturn os::get_native_priority(const Thread* const thread, int *priority_ptr) {
2950 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) {
2951 *priority_ptr = java_to_os_priority[NormPriority];
2952 return OS_OK;
2953 }
2954
2955 errno = 0;
2956 *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id());
2957 return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR);
2958 }
2959
2960 // Hint to the underlying OS that a task switch would not be good.
2961 // Void return because it's a hint and can fail.
2962 void os::hint_no_preempt() {}
2963
2964 ////////////////////////////////////////////////////////////////////////////////
2965 // suspend/resume support
2966
2967 // the low-level signal-based suspend/resume support is a remnant from the
2968 // old VM-suspension that used to be for java-suspension, safepoints etc,
2969 // within hotspot. Now there is a single use-case for this:
2970 // - calling get_thread_pc() on the VMThread by the flat-profiler task
2971 // that runs in the watcher thread.
2972 // The remaining code is greatly simplified from the more general suspension
2973 // code that used to be used.
2974 //
2975 // The protocol is quite simple:
2976 // - suspend:
2977 // - sends a signal to the target thread
2978 // - polls the suspend state of the osthread using a yield loop
2979 // - target thread signal handler (SR_handler) sets suspend state
2980 // and blocks in sigsuspend until continued
2981 // - resume:
2982 // - sets target osthread state to continue
2983 // - sends signal to end the sigsuspend loop in the SR_handler
2984 //
2985 // Note that the SR_lock plays no role in this suspend/resume protocol.
2986 //
2987
2988 static void resume_clear_context(OSThread *osthread) {
2989 osthread->set_ucontext(NULL);
2990 osthread->set_siginfo(NULL);
2991
2992 // notify the suspend action is completed, we have now resumed
2993 osthread->sr.clear_suspended();
2994 }
2995
2996 static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo, ucontext_t* context) {
2997 osthread->set_ucontext(context);
2998 osthread->set_siginfo(siginfo);
2999 }
3000
3001 //
3002 // Handler function invoked when a thread's execution is suspended or
3003 // resumed. We have to be careful that only async-safe functions are
3004 // called here (Note: most pthread functions are not async safe and
3005 // should be avoided.)
3006 //
3007 // Note: sigwait() is a more natural fit than sigsuspend() from an
3008 // interface point of view, but sigwait() prevents the signal hander
3009 // from being run. libpthread would get very confused by not having
3010 // its signal handlers run and prevents sigwait()'s use with the
3011 // mutex granting granting signal.
3012 //
3013 // Currently only ever called on the VMThread
3014 //
3015 static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) {
3016 // Save and restore errno to avoid confusing native code with EINTR
3017 // after sigsuspend.
3018 int old_errno = errno;
3019
3020 Thread* thread = Thread::current();
3021 OSThread* osthread = thread->osthread();
3022 assert(thread->is_VM_thread(), "Must be VMThread");
3023 // read current suspend action
3024 int action = osthread->sr.suspend_action();
3025 if (action == SR_SUSPEND) {
3026 suspend_save_context(osthread, siginfo, context);
3027
3028 // Notify the suspend action is about to be completed. do_suspend()
3029 // waits until SR_SUSPENDED is set and then returns. We will wait
3030 // here for a resume signal and that completes the suspend-other
3031 // action. do_suspend/do_resume is always called as a pair from
3032 // the same thread - so there are no races
3033
3034 // notify the caller
3035 osthread->sr.set_suspended();
3036
3037 sigset_t suspend_set; // signals for sigsuspend()
3038
3039 // get current set of blocked signals and unblock resume signal
3040 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set);
3041 sigdelset(&suspend_set, SR_signum);
3042
3043 // wait here until we are resumed
3044 do {
3045 sigsuspend(&suspend_set);
3046 // ignore all returns until we get a resume signal
3047 } while (osthread->sr.suspend_action() != SR_CONTINUE);
3048
3049 resume_clear_context(osthread);
3050
3051 } else {
3052 assert(action == SR_CONTINUE, "unexpected sr action");
3053 // nothing special to do - just leave the handler
3054 }
3055
3056 errno = old_errno;
3057 }
3058
3059
3060 static int SR_initialize() {
3061 struct sigaction act;
3062 char *s;
3063 /* Get signal number to use for suspend/resume */
3064 if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) {
3065 int sig = ::strtol(s, 0, 10);
3066 if (sig > 0 || sig < _NSIG) {
3067 SR_signum = sig;
3068 }
3069 }
3070
3071 assert(SR_signum > SIGSEGV && SR_signum > SIGBUS,
3072 "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769");
3073
3074 sigemptyset(&SR_sigset);
3075 sigaddset(&SR_sigset, SR_signum);
3076
3077 /* Set up signal handler for suspend/resume */
3078 act.sa_flags = SA_RESTART|SA_SIGINFO;
3079 act.sa_handler = (void (*)(int)) SR_handler;
3080
3081 // SR_signum is blocked by default.
3082 // 4528190 - We also need to block pthread restart signal (32 on all
3083 // supported Linux platforms). Note that LinuxThreads need to block
3084 // this signal for all threads to work properly. So we don't have
3085 // to use hard-coded signal number when setting up the mask.
3086 pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask);
3087
3088 if (sigaction(SR_signum, &act, 0) == -1) {
3089 return -1;
3090 }
3091
3092 // Save signal flag
3093 os::Linux::set_our_sigflags(SR_signum, act.sa_flags);
3094 return 0;
3095 }
3096
3097 static int SR_finalize() {
3098 return 0;
3099 }
3100
3101
3102 // returns true on success and false on error - really an error is fatal
3103 // but this seems the normal response to library errors
3104 static bool do_suspend(OSThread* osthread) {
3105 // mark as suspended and send signal
3106 osthread->sr.set_suspend_action(SR_SUSPEND);
3107 int status = pthread_kill(osthread->pthread_id(), SR_signum);
3108 assert_status(status == 0, status, "pthread_kill");
3109
3110 // check status and wait until notified of suspension
3111 if (status == 0) {
3112 for (int i = 0; !osthread->sr.is_suspended(); i++) {
3113 os::yield_all(i);
3114 }
3115 osthread->sr.set_suspend_action(SR_NONE);
3116 return true;
3117 }
3118 else {
3119 osthread->sr.set_suspend_action(SR_NONE);
3120 return false;
3121 }
3122 }
3123
3124 static void do_resume(OSThread* osthread) {
3125 assert(osthread->sr.is_suspended(), "thread should be suspended");
3126 osthread->sr.set_suspend_action(SR_CONTINUE);
3127
3128 int status = pthread_kill(osthread->pthread_id(), SR_signum);
3129 assert_status(status == 0, status, "pthread_kill");
3130 // check status and wait unit notified of resumption
3131 if (status == 0) {
3132 for (int i = 0; osthread->sr.is_suspended(); i++) {
3133 os::yield_all(i);
3134 }
3135 }
3136 osthread->sr.set_suspend_action(SR_NONE);
3137 }
3138
3139 ////////////////////////////////////////////////////////////////////////////////
3140 // interrupt support
3141
3142 void os::interrupt(Thread* thread) {
3143 assert(Thread::current() == thread || Threads_lock->owned_by_self(),
3144 "possibility of dangling Thread pointer");
3145
3146 OSThread* osthread = thread->osthread();
3147
3148 if (!osthread->interrupted()) {
3149 osthread->set_interrupted(true);
3150 // More than one thread can get here with the same value of osthread,
3151 // resulting in multiple notifications. We do, however, want the store
3152 // to interrupted() to be visible to other threads before we execute unpark().
3153 OrderAccess::fence();
3154 ParkEvent * const slp = thread->_SleepEvent ;
3155 if (slp != NULL) slp->unpark() ;
3156 }
3157
3158 // For JSR166. Unpark even if interrupt status already was set
3159 if (thread->is_Java_thread())
3160 ((JavaThread*)thread)->parker()->unpark();
3161
3162 ParkEvent * ev = thread->_ParkEvent ;
3163 if (ev != NULL) ev->unpark() ;
3164
3165 }
3166
3167 bool os::is_interrupted(Thread* thread, bool clear_interrupted) {
3168 assert(Thread::current() == thread || Threads_lock->owned_by_self(),
3169 "possibility of dangling Thread pointer");
3170
3171 OSThread* osthread = thread->osthread();
3172
3173 bool interrupted = osthread->interrupted();
3174
3175 if (interrupted && clear_interrupted) {
3176 osthread->set_interrupted(false);
3177 // consider thread->_SleepEvent->reset() ... optional optimization
3178 }
3179
3180 return interrupted;
3181 }
3182
3183 ///////////////////////////////////////////////////////////////////////////////////
3184 // signal handling (except suspend/resume)
3185
3186 // This routine may be used by user applications as a "hook" to catch signals.
3187 // The user-defined signal handler must pass unrecognized signals to this
3188 // routine, and if it returns true (non-zero), then the signal handler must
3189 // return immediately. If the flag "abort_if_unrecognized" is true, then this
3190 // routine will never retun false (zero), but instead will execute a VM panic
3191 // routine kill the process.
3192 //
3193 // If this routine returns false, it is OK to call it again. This allows
3194 // the user-defined signal handler to perform checks either before or after
3195 // the VM performs its own checks. Naturally, the user code would be making
3196 // a serious error if it tried to handle an exception (such as a null check
3197 // or breakpoint) that the VM was generating for its own correct operation.
3198 //
3199 // This routine may recognize any of the following kinds of signals:
3200 // SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1.
3201 // It should be consulted by handlers for any of those signals.
3202 //
3203 // The caller of this routine must pass in the three arguments supplied
3204 // to the function referred to in the "sa_sigaction" (not the "sa_handler")
3205 // field of the structure passed to sigaction(). This routine assumes that
3206 // the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART.
3207 //
3208 // Note that the VM will print warnings if it detects conflicting signal
3209 // handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers".
3210 //
3211 extern "C" int
3212 JVM_handle_linux_signal(int signo, siginfo_t* siginfo,
3213 void* ucontext, int abort_if_unrecognized);
3214
3215 void signalHandler(int sig, siginfo_t* info, void* uc) {
3216 assert(info != NULL && uc != NULL, "it must be old kernel");
3217 JVM_handle_linux_signal(sig, info, uc, true);
3218 }
3219
3220
3221 // This boolean allows users to forward their own non-matching signals
3222 // to JVM_handle_linux_signal, harmlessly.
3223 bool os::Linux::signal_handlers_are_installed = false;
3224
3225 // For signal-chaining
3226 struct sigaction os::Linux::sigact[MAXSIGNUM];
3227 unsigned int os::Linux::sigs = 0;
3228 bool os::Linux::libjsig_is_loaded = false;
3229 typedef struct sigaction *(*get_signal_t)(int);
3230 get_signal_t os::Linux::get_signal_action = NULL;
3231
3232 struct sigaction* os::Linux::get_chained_signal_action(int sig) {
3233 struct sigaction *actp = NULL;
3234
3235 if (libjsig_is_loaded) {
3236 // Retrieve the old signal handler from libjsig
3237 actp = (*get_signal_action)(sig);
3238 }
3239 if (actp == NULL) {
3240 // Retrieve the preinstalled signal handler from jvm
3241 actp = get_preinstalled_handler(sig);
3242 }
3243
3244 return actp;
3245 }
3246
3247 static bool call_chained_handler(struct sigaction *actp, int sig,
3248 siginfo_t *siginfo, void *context) {
3249 // Call the old signal handler
3250 if (actp->sa_handler == SIG_DFL) {
3251 // It's more reasonable to let jvm treat it as an unexpected exception
3252 // instead of taking the default action.
3253 return false;
3254 } else if (actp->sa_handler != SIG_IGN) {
3255 if ((actp->sa_flags & SA_NODEFER) == 0) {
3256 // automaticlly block the signal
3257 sigaddset(&(actp->sa_mask), sig);
3258 }
3259
3260 sa_handler_t hand;
3261 sa_sigaction_t sa;
3262 bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0;
3263 // retrieve the chained handler
3264 if (siginfo_flag_set) {
3265 sa = actp->sa_sigaction;
3266 } else {
3267 hand = actp->sa_handler;
3268 }
3269
3270 if ((actp->sa_flags & SA_RESETHAND) != 0) {
3271 actp->sa_handler = SIG_DFL;
3272 }
3273
3274 // try to honor the signal mask
3275 sigset_t oset;
3276 pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset);
3277
3278 // call into the chained handler
3279 if (siginfo_flag_set) {
3280 (*sa)(sig, siginfo, context);
3281 } else {
3282 (*hand)(sig);
3283 }
3284
3285 // restore the signal mask
3286 pthread_sigmask(SIG_SETMASK, &oset, 0);
3287 }
3288 // Tell jvm's signal handler the signal is taken care of.
3289 return true;
3290 }
3291
3292 bool os::Linux::chained_handler(int sig, siginfo_t* siginfo, void* context) {
3293 bool chained = false;
3294 // signal-chaining
3295 if (UseSignalChaining) {
3296 struct sigaction *actp = get_chained_signal_action(sig);
3297 if (actp != NULL) {
3298 chained = call_chained_handler(actp, sig, siginfo, context);
3299 }
3300 }
3301 return chained;
3302 }
3303
3304 struct sigaction* os::Linux::get_preinstalled_handler(int sig) {
3305 if ((( (unsigned int)1 << sig ) & sigs) != 0) {
3306 return &sigact[sig];
3307 }
3308 return NULL;
3309 }
3310
3311 void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) {
3312 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
3313 sigact[sig] = oldAct;
3314 sigs |= (unsigned int)1 << sig;
3315 }
3316
3317 // for diagnostic
3318 int os::Linux::sigflags[MAXSIGNUM];
3319
3320 int os::Linux::get_our_sigflags(int sig) {
3321 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
3322 return sigflags[sig];
3323 }
3324
3325 void os::Linux::set_our_sigflags(int sig, int flags) {
3326 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
3327 sigflags[sig] = flags;
3328 }
3329
3330 void os::Linux::set_signal_handler(int sig, bool set_installed) {
3331 // Check for overwrite.
3332 struct sigaction oldAct;
3333 sigaction(sig, (struct sigaction*)NULL, &oldAct);
3334
3335 void* oldhand = oldAct.sa_sigaction
3336 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction)
3337 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler);
3338 if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) &&
3339 oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) &&
3340 oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) {
3341 if (AllowUserSignalHandlers || !set_installed) {
3342 // Do not overwrite; user takes responsibility to forward to us.
3343 return;
3344 } else if (UseSignalChaining) {
3345 // save the old handler in jvm
3346 save_preinstalled_handler(sig, oldAct);
3347 // libjsig also interposes the sigaction() call below and saves the
3348 // old sigaction on it own.
3349 } else {
3350 fatal2("Encountered unexpected pre-existing sigaction handler %#lx for signal %d.", (long)oldhand, sig);
3351 }
3352 }
3353
3354 struct sigaction sigAct;
3355 sigfillset(&(sigAct.sa_mask));
3356 sigAct.sa_handler = SIG_DFL;
3357 if (!set_installed) {
3358 sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
3359 } else {
3360 sigAct.sa_sigaction = signalHandler;
3361 sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
3362 }
3363 // Save flags, which are set by ours
3364 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
3365 sigflags[sig] = sigAct.sa_flags;
3366
3367 int ret = sigaction(sig, &sigAct, &oldAct);
3368 assert(ret == 0, "check");
3369
3370 void* oldhand2 = oldAct.sa_sigaction
3371 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction)
3372 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler);
3373 assert(oldhand2 == oldhand, "no concurrent signal handler installation");
3374 }
3375
3376 // install signal handlers for signals that HotSpot needs to
3377 // handle in order to support Java-level exception handling.
3378
3379 void os::Linux::install_signal_handlers() {
3380 if (!signal_handlers_are_installed) {
3381 signal_handlers_are_installed = true;
3382
3383 // signal-chaining
3384 typedef void (*signal_setting_t)();
3385 signal_setting_t begin_signal_setting = NULL;
3386 signal_setting_t end_signal_setting = NULL;
3387 begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
3388 dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting"));
3389 if (begin_signal_setting != NULL) {
3390 end_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
3391 dlsym(RTLD_DEFAULT, "JVM_end_signal_setting"));
3392 get_signal_action = CAST_TO_FN_PTR(get_signal_t,
3393 dlsym(RTLD_DEFAULT, "JVM_get_signal_action"));
3394 libjsig_is_loaded = true;
3395 assert(UseSignalChaining, "should enable signal-chaining");
3396 }
3397 if (libjsig_is_loaded) {
3398 // Tell libjsig jvm is setting signal handlers
3399 (*begin_signal_setting)();
3400 }
3401
3402 set_signal_handler(SIGSEGV, true);
3403 set_signal_handler(SIGPIPE, true);
3404 set_signal_handler(SIGBUS, true);
3405 set_signal_handler(SIGILL, true);
3406 set_signal_handler(SIGFPE, true);
3407 set_signal_handler(SIGXFSZ, true);
3408
3409 if (libjsig_is_loaded) {
3410 // Tell libjsig jvm finishes setting signal handlers
3411 (*end_signal_setting)();
3412 }
3413
3414 // We don't activate signal checker if libjsig is in place, we trust ourselves
3415 // and if UserSignalHandler is installed all bets are off
3416 if (CheckJNICalls) {
3417 if (libjsig_is_loaded) {
3418 tty->print_cr("Info: libjsig is activated, all active signal checking is disabled");
3419 check_signals = false;
3420 }
3421 if (AllowUserSignalHandlers) {
3422 tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled");
3423 check_signals = false;
3424 }
3425 }
3426 }
3427 }
3428
3429 // This is the fastest way to get thread cpu time on Linux.
3430 // Returns cpu time (user+sys) for any thread, not only for current.
3431 // POSIX compliant clocks are implemented in the kernels 2.6.16+.
3432 // It might work on 2.6.10+ with a special kernel/glibc patch.
3433 // For reference, please, see IEEE Std 1003.1-2004:
3434 // http://www.unix.org/single_unix_specification
3435
3436 jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) {
3437 struct timespec tp;
3438 int rc = os::Linux::clock_gettime(clockid, &tp);
3439 assert(rc == 0, "clock_gettime is expected to return 0 code");
3440
3441 return (tp.tv_sec * SEC_IN_NANOSECS) + tp.tv_nsec;
3442 }
3443
3444 /////
3445 // glibc on Linux platform uses non-documented flag
3446 // to indicate, that some special sort of signal
3447 // trampoline is used.
3448 // We will never set this flag, and we should
3449 // ignore this flag in our diagnostic
3450 #ifdef SIGNIFICANT_SIGNAL_MASK
3451 #undef SIGNIFICANT_SIGNAL_MASK
3452 #endif
3453 #define SIGNIFICANT_SIGNAL_MASK (~0x04000000)
3454
3455 static const char* get_signal_handler_name(address handler,
3456 char* buf, int buflen) {
3457 int offset;
3458 bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset);
3459 if (found) {
3460 // skip directory names
3461 const char *p1, *p2;
3462 p1 = buf;
3463 size_t len = strlen(os::file_separator());
3464 while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len;
3465 jio_snprintf(buf, buflen, "%s+0x%x", p1, offset);
3466 } else {
3467 jio_snprintf(buf, buflen, PTR_FORMAT, handler);
3468 }
3469 return buf;
3470 }
3471
3472 static void print_signal_handler(outputStream* st, int sig,
3473 char* buf, size_t buflen) {
3474 struct sigaction sa;
3475
3476 sigaction(sig, NULL, &sa);
3477
3478 // See comment for SIGNIFICANT_SIGNAL_MASK define
3479 sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
3480
3481 st->print("%s: ", os::exception_name(sig, buf, buflen));
3482
3483 address handler = (sa.sa_flags & SA_SIGINFO)
3484 ? CAST_FROM_FN_PTR(address, sa.sa_sigaction)
3485 : CAST_FROM_FN_PTR(address, sa.sa_handler);
3486
3487 if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) {
3488 st->print("SIG_DFL");
3489 } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) {
3490 st->print("SIG_IGN");
3491 } else {
3492 st->print("[%s]", get_signal_handler_name(handler, buf, buflen));
3493 }
3494
3495 st->print(", sa_mask[0]=" PTR32_FORMAT, *(uint32_t*)&sa.sa_mask);
3496
3497 address rh = VMError::get_resetted_sighandler(sig);
3498 // May be, handler was resetted by VMError?
3499 if(rh != NULL) {
3500 handler = rh;
3501 sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK;
3502 }
3503
3504 st->print(", sa_flags=" PTR32_FORMAT, sa.sa_flags);
3505
3506 // Check: is it our handler?
3507 if(handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) ||
3508 handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) {
3509 // It is our signal handler
3510 // check for flags, reset system-used one!
3511 if((int)sa.sa_flags != os::Linux::get_our_sigflags(sig)) {
3512 st->print(
3513 ", flags was changed from " PTR32_FORMAT ", consider using jsig library",
3514 os::Linux::get_our_sigflags(sig));
3515 }
3516 }
3517 st->cr();
3518 }
3519
3520
3521 #define DO_SIGNAL_CHECK(sig) \
3522 if (!sigismember(&check_signal_done, sig)) \
3523 os::Linux::check_signal_handler(sig)
3524
3525 // This method is a periodic task to check for misbehaving JNI applications
3526 // under CheckJNI, we can add any periodic checks here
3527
3528 void os::run_periodic_checks() {
3529
3530 if (check_signals == false) return;
3531
3532 // SEGV and BUS if overridden could potentially prevent
3533 // generation of hs*.log in the event of a crash, debugging
3534 // such a case can be very challenging, so we absolutely
3535 // check the following for a good measure:
3536 DO_SIGNAL_CHECK(SIGSEGV);
3537 DO_SIGNAL_CHECK(SIGILL);
3538 DO_SIGNAL_CHECK(SIGFPE);
3539 DO_SIGNAL_CHECK(SIGBUS);
3540 DO_SIGNAL_CHECK(SIGPIPE);
3541 DO_SIGNAL_CHECK(SIGXFSZ);
3542
3543
3544 // ReduceSignalUsage allows the user to override these handlers
3545 // see comments at the very top and jvm_solaris.h
3546 if (!ReduceSignalUsage) {
3547 DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL);
3548 DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL);
3549 DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL);
3550 DO_SIGNAL_CHECK(BREAK_SIGNAL);
3551 }
3552
3553 DO_SIGNAL_CHECK(SR_signum);
3554 DO_SIGNAL_CHECK(INTERRUPT_SIGNAL);
3555 }
3556
3557 typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *);
3558
3559 static os_sigaction_t os_sigaction = NULL;
3560
3561 void os::Linux::check_signal_handler(int sig) {
3562 char buf[O_BUFLEN];
3563 address jvmHandler = NULL;
3564
3565
3566 struct sigaction act;
3567 if (os_sigaction == NULL) {
3568 // only trust the default sigaction, in case it has been interposed
3569 os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction");
3570 if (os_sigaction == NULL) return;
3571 }
3572
3573 os_sigaction(sig, (struct sigaction*)NULL, &act);
3574
3575
3576 act.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
3577
3578 address thisHandler = (act.sa_flags & SA_SIGINFO)
3579 ? CAST_FROM_FN_PTR(address, act.sa_sigaction)
3580 : CAST_FROM_FN_PTR(address, act.sa_handler) ;
3581
3582
3583 switch(sig) {
3584 case SIGSEGV:
3585 case SIGBUS:
3586 case SIGFPE:
3587 case SIGPIPE:
3588 case SIGILL:
3589 case SIGXFSZ:
3590 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler);
3591 break;
3592
3593 case SHUTDOWN1_SIGNAL:
3594 case SHUTDOWN2_SIGNAL:
3595 case SHUTDOWN3_SIGNAL:
3596 case BREAK_SIGNAL:
3597 jvmHandler = (address)user_handler();
3598 break;
3599
3600 case INTERRUPT_SIGNAL:
3601 jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL);
3602 break;
3603
3604 default:
3605 if (sig == SR_signum) {
3606 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler);
3607 } else {
3608 return;
3609 }
3610 break;
3611 }
3612
3613 if (thisHandler != jvmHandler) {
3614 tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN));
3615 tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN));
3616 tty->print_cr(" found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN));
3617 // No need to check this sig any longer
3618 sigaddset(&check_signal_done, sig);
3619 } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) {
3620 tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN));
3621 tty->print("expected:" PTR32_FORMAT, os::Linux::get_our_sigflags(sig));
3622 tty->print_cr(" found:" PTR32_FORMAT, act.sa_flags);
3623 // No need to check this sig any longer
3624 sigaddset(&check_signal_done, sig);
3625 }
3626
3627 // Dump all the signal
3628 if (sigismember(&check_signal_done, sig)) {
3629 print_signal_handlers(tty, buf, O_BUFLEN);
3630 }
3631 }
3632
3633 extern void report_error(char* file_name, int line_no, char* title, char* format, ...);
3634
3635 extern bool signal_name(int signo, char* buf, size_t len);
3636
3637 const char* os::exception_name(int exception_code, char* buf, size_t size) {
3638 if (0 < exception_code && exception_code <= SIGRTMAX) {
3639 // signal
3640 if (!signal_name(exception_code, buf, size)) {
3641 jio_snprintf(buf, size, "SIG%d", exception_code);
3642 }
3643 return buf;
3644 } else {
3645 return NULL;
3646 }
3647 }
3648
3649 // this is called _before_ the most of global arguments have been parsed
3650 void os::init(void) {
3651 char dummy; /* used to get a guess on initial stack address */
3652 // first_hrtime = gethrtime();
3653
3654 // With LinuxThreads the JavaMain thread pid (primordial thread)
3655 // is different than the pid of the java launcher thread.
3656 // So, on Linux, the launcher thread pid is passed to the VM
3657 // via the sun.java.launcher.pid property.
3658 // Use this property instead of getpid() if it was correctly passed.
3659 // See bug 6351349.
3660 pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid();
3661
3662 _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid();
3663
3664 clock_tics_per_sec = sysconf(_SC_CLK_TCK);
3665
3666 init_random(1234567);
3667
3668 ThreadCritical::initialize();
3669
3670 Linux::set_page_size(sysconf(_SC_PAGESIZE));
3671 if (Linux::page_size() == -1) {
3672 fatal1("os_linux.cpp: os::init: sysconf failed (%s)", strerror(errno));
3673 }
3674 init_page_sizes((size_t) Linux::page_size());
3675
3676 Linux::initialize_system_info();
3677
3678 // main_thread points to the aboriginal thread
3679 Linux::_main_thread = pthread_self();
3680
3681 Linux::clock_init();
3682 initial_time_count = os::elapsed_counter();
3683 pthread_mutex_init(&dl_mutex, NULL);
3684 }
3685
3686 // To install functions for atexit system call
3687 extern "C" {
3688 static void perfMemory_exit_helper() {
3689 perfMemory_exit();
3690 }
3691 }
3692
3693 // this is called _after_ the global arguments have been parsed
3694 jint os::init_2(void)
3695 {
3696 Linux::fast_thread_clock_init();
3697
3698 // Allocate a single page and mark it as readable for safepoint polling
3699 address polling_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
3700 guarantee( polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page" );
3701
3702 os::set_polling_page( polling_page );
3703
3704 #ifndef PRODUCT
3705 if(Verbose && PrintMiscellaneous)
3706 tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n", (intptr_t)polling_page);
3707 #endif
3708
3709 if (!UseMembar) {
3710 address mem_serialize_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
3711 guarantee( mem_serialize_page != NULL, "mmap Failed for memory serialize page");
3712 os::set_memory_serialize_page( mem_serialize_page );
3713
3714 #ifndef PRODUCT
3715 if(Verbose && PrintMiscellaneous)
3716 tty->print("[Memory Serialize Page address: " INTPTR_FORMAT "]\n", (intptr_t)mem_serialize_page);
3717 #endif
3718 }
3719
3720 FLAG_SET_DEFAULT(UseLargePages, os::large_page_init());
3721
3722 // initialize suspend/resume support - must do this before signal_sets_init()
3723 if (SR_initialize() != 0) {
3724 perror("SR_initialize failed");
3725 return JNI_ERR;
3726 }
3727
3728 Linux::signal_sets_init();
3729 Linux::install_signal_handlers();
3730
3731 size_t threadStackSizeInBytes = ThreadStackSize * K;
3732 if (threadStackSizeInBytes != 0 &&
3733 threadStackSizeInBytes < Linux::min_stack_allowed) {
3734 tty->print_cr("\nThe stack size specified is too small, "
3735 "Specify at least %dk",
3736 Linux::min_stack_allowed / K);
3737 return JNI_ERR;
3738 }
3739
3740 // Make the stack size a multiple of the page size so that
3741 // the yellow/red zones can be guarded.
3742 JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes,
3743 vm_page_size()));
3744
3745 Linux::capture_initial_stack(JavaThread::stack_size_at_create());
3746
3747 Linux::libpthread_init();
3748 if (PrintMiscellaneous && (Verbose || WizardMode)) {
3749 tty->print_cr("[HotSpot is running with %s, %s(%s)]\n",
3750 Linux::glibc_version(), Linux::libpthread_version(),
3751 Linux::is_floating_stack() ? "floating stack" : "fixed stack");
3752 }
3753
3754 if (UseNUMA) {
3755 if (!Linux::libnuma_init()) {
3756 UseNUMA = false;
3757 } else {
3758 if ((Linux::numa_max_node() < 1)) {
3759 // There's only one node(they start from 0), disable NUMA.
3760 UseNUMA = false;
3761 }
3762 }
3763 if (!UseNUMA && ForceNUMA) {
3764 UseNUMA = true;
3765 }
3766 }
3767
3768 if (MaxFDLimit) {
3769 // set the number of file descriptors to max. print out error
3770 // if getrlimit/setrlimit fails but continue regardless.
3771 struct rlimit nbr_files;
3772 int status = getrlimit(RLIMIT_NOFILE, &nbr_files);
3773 if (status != 0) {
3774 if (PrintMiscellaneous && (Verbose || WizardMode))
3775 perror("os::init_2 getrlimit failed");
3776 } else {
3777 nbr_files.rlim_cur = nbr_files.rlim_max;
3778 status = setrlimit(RLIMIT_NOFILE, &nbr_files);
3779 if (status != 0) {
3780 if (PrintMiscellaneous && (Verbose || WizardMode))
3781 perror("os::init_2 setrlimit failed");
3782 }
3783 }
3784 }
3785
3786 // Initialize lock used to serialize thread creation (see os::create_thread)
3787 Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false));
3788
3789 // Initialize HPI.
3790 jint hpi_result = hpi::initialize();
3791 if (hpi_result != JNI_OK) {
3792 tty->print_cr("There was an error trying to initialize the HPI library.");
3793 return hpi_result;
3794 }
3795
3796 // at-exit methods are called in the reverse order of their registration.
3797 // atexit functions are called on return from main or as a result of a
3798 // call to exit(3C). There can be only 32 of these functions registered
3799 // and atexit() does not set errno.
3800
3801 if (PerfAllowAtExitRegistration) {
3802 // only register atexit functions if PerfAllowAtExitRegistration is set.
3803 // atexit functions can be delayed until process exit time, which
3804 // can be problematic for embedded VM situations. Embedded VMs should
3805 // call DestroyJavaVM() to assure that VM resources are released.
3806
3807 // note: perfMemory_exit_helper atexit function may be removed in
3808 // the future if the appropriate cleanup code can be added to the
3809 // VM_Exit VMOperation's doit method.
3810 if (atexit(perfMemory_exit_helper) != 0) {
3811 warning("os::init2 atexit(perfMemory_exit_helper) failed");
3812 }
3813 }
3814
3815 // initialize thread priority policy
3816 prio_init();
3817
3818 return JNI_OK;
3819 }
3820
3821 // Mark the polling page as unreadable
3822 void os::make_polling_page_unreadable(void) {
3823 if( !guard_memory((char*)_polling_page, Linux::page_size()) )
3824 fatal("Could not disable polling page");
3825 };
3826
3827 // Mark the polling page as readable
3828 void os::make_polling_page_readable(void) {
3829 if( !linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) {
3830 fatal("Could not enable polling page");
3831 }
3832 };
3833
3834 int os::active_processor_count() {
3835 // Linux doesn't yet have a (official) notion of processor sets,
3836 // so just return the number of online processors.
3837 int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN);
3838 assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check");
3839 return online_cpus;
3840 }
3841
3842 bool os::distribute_processes(uint length, uint* distribution) {
3843 // Not yet implemented.
3844 return false;
3845 }
3846
3847 bool os::bind_to_processor(uint processor_id) {
3848 // Not yet implemented.
3849 return false;
3850 }
3851
3852 ///
3853
3854 // Suspends the target using the signal mechanism and then grabs the PC before
3855 // resuming the target. Used by the flat-profiler only
3856 ExtendedPC os::get_thread_pc(Thread* thread) {
3857 // Make sure that it is called by the watcher for the VMThread
3858 assert(Thread::current()->is_Watcher_thread(), "Must be watcher");
3859 assert(thread->is_VM_thread(), "Can only be called for VMThread");
3860
3861 ExtendedPC epc;
3862
3863 OSThread* osthread = thread->osthread();
3864 if (do_suspend(osthread)) {
3865 if (osthread->ucontext() != NULL) {
3866 epc = os::Linux::ucontext_get_pc(osthread->ucontext());
3867 } else {
3868 // NULL context is unexpected, double-check this is the VMThread
3869 guarantee(thread->is_VM_thread(), "can only be called for VMThread");
3870 }
3871 do_resume(osthread);
3872 }
3873 // failure means pthread_kill failed for some reason - arguably this is
3874 // a fatal problem, but such problems are ignored elsewhere
3875
3876 return epc;
3877 }
3878
3879 int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond, pthread_mutex_t *_mutex, const struct timespec *_abstime)
3880 {
3881 if (is_NPTL()) {
3882 return pthread_cond_timedwait(_cond, _mutex, _abstime);
3883 } else {
3884 #ifndef IA64
3885 // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control
3886 // word back to default 64bit precision if condvar is signaled. Java
3887 // wants 53bit precision. Save and restore current value.
3888 int fpu = get_fpu_control_word();
3889 #endif // IA64
3890 int status = pthread_cond_timedwait(_cond, _mutex, _abstime);
3891 #ifndef IA64
3892 set_fpu_control_word(fpu);
3893 #endif // IA64
3894 return status;
3895 }
3896 }
3897
3898 ////////////////////////////////////////////////////////////////////////////////
3899 // debug support
3900
3901 #ifndef PRODUCT
3902 static address same_page(address x, address y) {
3903 int page_bits = -os::vm_page_size();
3904 if ((intptr_t(x) & page_bits) == (intptr_t(y) & page_bits))
3905 return x;
3906 else if (x > y)
3907 return (address)(intptr_t(y) | ~page_bits) + 1;
3908 else
3909 return (address)(intptr_t(y) & page_bits);
3910 }
3911
3912 bool os::find(address addr) {
3913 Dl_info dlinfo;
3914 memset(&dlinfo, 0, sizeof(dlinfo));
3915 if (dladdr(addr, &dlinfo)) {
3916 tty->print(PTR_FORMAT ": ", addr);
3917 if (dlinfo.dli_sname != NULL) {
3918 tty->print("%s+%#x", dlinfo.dli_sname,
3919 addr - (intptr_t)dlinfo.dli_saddr);
3920 } else if (dlinfo.dli_fname) {
3921 tty->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase);
3922 } else {
3923 tty->print("<absolute address>");
3924 }
3925 if (dlinfo.dli_fname) {
3926 tty->print(" in %s", dlinfo.dli_fname);
3927 }
3928 if (dlinfo.dli_fbase) {
3929 tty->print(" at " PTR_FORMAT, dlinfo.dli_fbase);
3930 }
3931 tty->cr();
3932
3933 if (Verbose) {
3934 // decode some bytes around the PC
3935 address begin = same_page(addr-40, addr);
3936 address end = same_page(addr+40, addr);
3937 address lowest = (address) dlinfo.dli_sname;
3938 if (!lowest) lowest = (address) dlinfo.dli_fbase;
3939 if (begin < lowest) begin = lowest;
3940 Dl_info dlinfo2;
3941 if (dladdr(end, &dlinfo2) && dlinfo2.dli_saddr != dlinfo.dli_saddr
3942 && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin)
3943 end = (address) dlinfo2.dli_saddr;
3944 Disassembler::decode(begin, end);
3945 }
3946 return true;
3947 }
3948 return false;
3949 }
3950
3951 #endif
3952
3953 ////////////////////////////////////////////////////////////////////////////////
3954 // misc
3955
3956 // This does not do anything on Linux. This is basically a hook for being
3957 // able to use structured exception handling (thread-local exception filters)
3958 // on, e.g., Win32.
3959 void
3960 os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method,
3961 JavaCallArguments* args, Thread* thread) {
3962 f(value, method, args, thread);
3963 }
3964
3965 void os::print_statistics() {
3966 }
3967
3968 int os::message_box(const char* title, const char* message) {
3969 int i;
3970 fdStream err(defaultStream::error_fd());
3971 for (i = 0; i < 78; i++) err.print_raw("=");
3972 err.cr();
3973 err.print_raw_cr(title);
3974 for (i = 0; i < 78; i++) err.print_raw("-");
3975 err.cr();
3976 err.print_raw_cr(message);
3977 for (i = 0; i < 78; i++) err.print_raw("=");
3978 err.cr();
3979
3980 char buf[16];
3981 // Prevent process from exiting upon "read error" without consuming all CPU
3982 while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); }
3983
3984 return buf[0] == 'y' || buf[0] == 'Y';
3985 }
3986
3987 int os::stat(const char *path, struct stat *sbuf) {
3988 char pathbuf[MAX_PATH];
3989 if (strlen(path) > MAX_PATH - 1) {
3990 errno = ENAMETOOLONG;
3991 return -1;
3992 }
3993 hpi::native_path(strcpy(pathbuf, path));
3994 return ::stat(pathbuf, sbuf);
3995 }
3996
3997 bool os::check_heap(bool force) {
3998 return true;
3999 }
4000
4001 int local_vsnprintf(char* buf, size_t count, const char* format, va_list args) {
4002 return ::vsnprintf(buf, count, format, args);
4003 }
4004
4005 // Is a (classpath) directory empty?
4006 bool os::dir_is_empty(const char* path) {
4007 DIR *dir = NULL;
4008 struct dirent *ptr;
4009
4010 dir = opendir(path);
4011 if (dir == NULL) return true;
4012
4013 /* Scan the directory */
4014 bool result = true;
4015 char buf[sizeof(struct dirent) + MAX_PATH];
4016 while (result && (ptr = ::readdir(dir)) != NULL) {
4017 if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) {
4018 result = false;
4019 }
4020 }
4021 closedir(dir);
4022 return result;
4023 }
4024
4025 // create binary file, rewriting existing file if required
4026 int os::create_binary_file(const char* path, bool rewrite_existing) {
4027 int oflags = O_WRONLY | O_CREAT;
4028 if (!rewrite_existing) {
4029 oflags |= O_EXCL;
4030 }
4031 return ::open64(path, oflags, S_IREAD | S_IWRITE);
4032 }
4033
4034 // return current position of file pointer
4035 jlong os::current_file_offset(int fd) {
4036 return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR);
4037 }
4038
4039 // move file pointer to the specified offset
4040 jlong os::seek_to_file_offset(int fd, jlong offset) {
4041 return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET);
4042 }
4043
4044 // Map a block of memory.
4045 char* os::map_memory(int fd, const char* file_name, size_t file_offset,
4046 char *addr, size_t bytes, bool read_only,
4047 bool allow_exec) {
4048 int prot;
4049 int flags;
4050
4051 if (read_only) {
4052 prot = PROT_READ;
4053 flags = MAP_SHARED;
4054 } else {
4055 prot = PROT_READ | PROT_WRITE;
4056 flags = MAP_PRIVATE;
4057 }
4058
4059 if (allow_exec) {
4060 prot |= PROT_EXEC;
4061 }
4062
4063 if (addr != NULL) {
4064 flags |= MAP_FIXED;
4065 }
4066
4067 char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags,
4068 fd, file_offset);
4069 if (mapped_address == MAP_FAILED) {
4070 return NULL;
4071 }
4072 return mapped_address;
4073 }
4074
4075
4076 // Remap a block of memory.
4077 char* os::remap_memory(int fd, const char* file_name, size_t file_offset,
4078 char *addr, size_t bytes, bool read_only,
4079 bool allow_exec) {
4080 // same as map_memory() on this OS
4081 return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only,
4082 allow_exec);
4083 }
4084
4085
4086 // Unmap a block of memory.
4087 bool os::unmap_memory(char* addr, size_t bytes) {
4088 return munmap(addr, bytes) == 0;
4089 }
4090
4091 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time);
4092
4093 static clockid_t thread_cpu_clockid(Thread* thread) {
4094 pthread_t tid = thread->osthread()->pthread_id();
4095 clockid_t clockid;
4096
4097 // Get thread clockid
4098 int rc = os::Linux::pthread_getcpuclockid(tid, &clockid);
4099 assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code");
4100 return clockid;
4101 }
4102
4103 // current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool)
4104 // are used by JVM M&M and JVMTI to get user+sys or user CPU time
4105 // of a thread.
4106 //
4107 // current_thread_cpu_time() and thread_cpu_time(Thread*) returns
4108 // the fast estimate available on the platform.
4109
4110 jlong os::current_thread_cpu_time() {
4111 if (os::Linux::supports_fast_thread_cpu_time()) {
4112 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
4113 } else {
4114 // return user + sys since the cost is the same
4115 return slow_thread_cpu_time(Thread::current(), true /* user + sys */);
4116 }
4117 }
4118
4119 jlong os::thread_cpu_time(Thread* thread) {
4120 // consistent with what current_thread_cpu_time() returns
4121 if (os::Linux::supports_fast_thread_cpu_time()) {
4122 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread));
4123 } else {
4124 return slow_thread_cpu_time(thread, true /* user + sys */);
4125 }
4126 }
4127
4128 jlong os::current_thread_cpu_time(bool user_sys_cpu_time) {
4129 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
4130 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
4131 } else {
4132 return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time);
4133 }
4134 }
4135
4136 jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
4137 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
4138 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread));
4139 } else {
4140 return slow_thread_cpu_time(thread, user_sys_cpu_time);
4141 }
4142 }
4143
4144 //
4145 // -1 on error.
4146 //
4147
4148 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
4149 static bool proc_pid_cpu_avail = true;
4150 static bool proc_task_unchecked = true;
4151 static const char *proc_stat_path = "/proc/%d/stat";
4152 pid_t tid = thread->osthread()->thread_id();
4153 int i;
4154 char *s;
4155 char stat[2048];
4156 int statlen;
4157 char proc_name[64];
4158 int count;
4159 long sys_time, user_time;
4160 char string[64];
4161 int idummy;
4162 long ldummy;
4163 FILE *fp;
4164
4165 // We first try accessing /proc/<pid>/cpu since this is faster to
4166 // process. If this file is not present (linux kernels 2.5 and above)
4167 // then we open /proc/<pid>/stat.
4168 if ( proc_pid_cpu_avail ) {
4169 sprintf(proc_name, "/proc/%d/cpu", tid);
4170 fp = fopen(proc_name, "r");
4171 if ( fp != NULL ) {
4172 count = fscanf( fp, "%s %lu %lu\n", string, &user_time, &sys_time);
4173 fclose(fp);
4174 if ( count != 3 ) return -1;
4175
4176 if (user_sys_cpu_time) {
4177 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec);
4178 } else {
4179 return (jlong)user_time * (1000000000 / clock_tics_per_sec);
4180 }
4181 }
4182 else proc_pid_cpu_avail = false;
4183 }
4184
4185 // The /proc/<tid>/stat aggregates per-process usage on
4186 // new Linux kernels 2.6+ where NPTL is supported.
4187 // The /proc/self/task/<tid>/stat still has the per-thread usage.
4188 // See bug 6328462.
4189 // There can be no directory /proc/self/task on kernels 2.4 with NPTL
4190 // and possibly in some other cases, so we check its availability.
4191 if (proc_task_unchecked && os::Linux::is_NPTL()) {
4192 // This is executed only once
4193 proc_task_unchecked = false;
4194 fp = fopen("/proc/self/task", "r");
4195 if (fp != NULL) {
4196 proc_stat_path = "/proc/self/task/%d/stat";
4197 fclose(fp);
4198 }
4199 }
4200
4201 sprintf(proc_name, proc_stat_path, tid);
4202 fp = fopen(proc_name, "r");
4203 if ( fp == NULL ) return -1;
4204 statlen = fread(stat, 1, 2047, fp);
4205 stat[statlen] = '\0';
4206 fclose(fp);
4207
4208 // Skip pid and the command string. Note that we could be dealing with
4209 // weird command names, e.g. user could decide to rename java launcher
4210 // to "java 1.4.2 :)", then the stat file would look like
4211 // 1234 (java 1.4.2 :)) R ... ...
4212 // We don't really need to know the command string, just find the last
4213 // occurrence of ")" and then start parsing from there. See bug 4726580.
4214 s = strrchr(stat, ')');
4215 i = 0;
4216 if (s == NULL ) return -1;
4217
4218 // Skip blank chars
4219 do s++; while (isspace(*s));
4220
4221 count = sscanf(s,"%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu",
4222 &idummy, &idummy, &idummy, &idummy, &idummy, &idummy,
4223 &ldummy, &ldummy, &ldummy, &ldummy, &ldummy,
4224 &user_time, &sys_time);
4225 if ( count != 13 ) return -1;
4226 if (user_sys_cpu_time) {
4227 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec);
4228 } else {
4229 return (jlong)user_time * (1000000000 / clock_tics_per_sec);
4230 }
4231 }
4232
4233 void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
4234 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits
4235 info_ptr->may_skip_backward = false; // elapsed time not wall time
4236 info_ptr->may_skip_forward = false; // elapsed time not wall time
4237 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned
4238 }
4239
4240 void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
4241 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits
4242 info_ptr->may_skip_backward = false; // elapsed time not wall time
4243 info_ptr->may_skip_forward = false; // elapsed time not wall time
4244 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned
4245 }
4246
4247 bool os::is_thread_cpu_time_supported() {
4248 return true;
4249 }
4250
4251 // System loadavg support. Returns -1 if load average cannot be obtained.
4252 // Linux doesn't yet have a (official) notion of processor sets,
4253 // so just return the system wide load average.
4254 int os::loadavg(double loadavg[], int nelem) {
4255 return ::getloadavg(loadavg, nelem);
4256 }
4257
4258 void os::pause() {
4259 char filename[MAX_PATH];
4260 if (PauseAtStartupFile && PauseAtStartupFile[0]) {
4261 jio_snprintf(filename, MAX_PATH, PauseAtStartupFile);
4262 } else {
4263 jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id());
4264 }
4265
4266 int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
4267 if (fd != -1) {
4268 struct stat buf;
4269 close(fd);
4270 while (::stat(filename, &buf) == 0) {
4271 (void)::poll(NULL, 0, 100);
4272 }
4273 } else {
4274 jio_fprintf(stderr,
4275 "Could not open pause file '%s', continuing immediately.\n", filename);
4276 }
4277 }
4278
4279 extern "C" {
4280
4281 /**
4282 * NOTE: the following code is to keep the green threads code
4283 * in the libjava.so happy. Once the green threads is removed,
4284 * these code will no longer be needed.
4285 */
4286 int
4287 jdk_waitpid(pid_t pid, int* status, int options) {
4288 return waitpid(pid, status, options);
4289 }
4290
4291 int
4292 fork1() {
4293 return fork();
4294 }
4295
4296 int
4297 jdk_sem_init(sem_t *sem, int pshared, unsigned int value) {
4298 return sem_init(sem, pshared, value);
4299 }
4300
4301 int
4302 jdk_sem_post(sem_t *sem) {
4303 return sem_post(sem);
4304 }
4305
4306 int
4307 jdk_sem_wait(sem_t *sem) {
4308 return sem_wait(sem);
4309 }
4310
4311 int
4312 jdk_pthread_sigmask(int how , const sigset_t* newmask, sigset_t* oldmask) {
4313 return pthread_sigmask(how , newmask, oldmask);
4314 }
4315
4316 }
4317
4318 // Refer to the comments in os_solaris.cpp park-unpark.
4319 //
4320 // Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can
4321 // hang indefinitely. For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable.
4322 // For specifics regarding the bug see GLIBC BUGID 261237 :
4323 // http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html.
4324 // Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future
4325 // will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar
4326 // is used. (The simple C test-case provided in the GLIBC bug report manifests the
4327 // hang). The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos()
4328 // and monitorenter when we're using 1-0 locking. All those operations may result in
4329 // calls to pthread_cond_timedwait(). Using LD_ASSUME_KERNEL to use an older version
4330 // of libpthread avoids the problem, but isn't practical.
4331 //
4332 // Possible remedies:
4333 //
4334 // 1. Establish a minimum relative wait time. 50 to 100 msecs seems to work.
4335 // This is palliative and probabilistic, however. If the thread is preempted
4336 // between the call to compute_abstime() and pthread_cond_timedwait(), more
4337 // than the minimum period may have passed, and the abstime may be stale (in the
4338 // past) resultin in a hang. Using this technique reduces the odds of a hang
4339 // but the JVM is still vulnerable, particularly on heavily loaded systems.
4340 //
4341 // 2. Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead
4342 // of the usual flag-condvar-mutex idiom. The write side of the pipe is set
4343 // NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo)
4344 // reduces to poll()+read(). This works well, but consumes 2 FDs per extant
4345 // thread.
4346 //
4347 // 3. Embargo pthread_cond_timedwait() and implement a native "chron" thread
4348 // that manages timeouts. We'd emulate pthread_cond_timedwait() by enqueuing
4349 // a timeout request to the chron thread and then blocking via pthread_cond_wait().
4350 // This also works well. In fact it avoids kernel-level scalability impediments
4351 // on certain platforms that don't handle lots of active pthread_cond_timedwait()
4352 // timers in a graceful fashion.
4353 //
4354 // 4. When the abstime value is in the past it appears that control returns
4355 // correctly from pthread_cond_timedwait(), but the condvar is left corrupt.
4356 // Subsequent timedwait/wait calls may hang indefinitely. Given that, we
4357 // can avoid the problem by reinitializing the condvar -- by cond_destroy()
4358 // followed by cond_init() -- after all calls to pthread_cond_timedwait().
4359 // It may be possible to avoid reinitialization by checking the return
4360 // value from pthread_cond_timedwait(). In addition to reinitializing the
4361 // condvar we must establish the invariant that cond_signal() is only called
4362 // within critical sections protected by the adjunct mutex. This prevents
4363 // cond_signal() from "seeing" a condvar that's in the midst of being
4364 // reinitialized or that is corrupt. Sadly, this invariant obviates the
4365 // desirable signal-after-unlock optimization that avoids futile context switching.
4366 //
4367 // I'm also concerned that some versions of NTPL might allocate an auxilliary
4368 // structure when a condvar is used or initialized. cond_destroy() would
4369 // release the helper structure. Our reinitialize-after-timedwait fix
4370 // put excessive stress on malloc/free and locks protecting the c-heap.
4371 //
4372 // We currently use (4). See the WorkAroundNTPLTimedWaitHang flag.
4373 // It may be possible to refine (4) by checking the kernel and NTPL verisons
4374 // and only enabling the work-around for vulnerable environments.
4375
4376 // utility to compute the abstime argument to timedwait:
4377 // millis is the relative timeout time
4378 // abstime will be the absolute timeout time
4379 // TODO: replace compute_abstime() with unpackTime()
4380
4381 static struct timespec* compute_abstime(timespec* abstime, jlong millis) {
4382 if (millis < 0) millis = 0;
4383 struct timeval now;
4384 int status = gettimeofday(&now, NULL);
4385 assert(status == 0, "gettimeofday");
4386 jlong seconds = millis / 1000;
4387 millis %= 1000;
4388 if (seconds > 50000000) { // see man cond_timedwait(3T)
4389 seconds = 50000000;
4390 }
4391 abstime->tv_sec = now.tv_sec + seconds;
4392 long usec = now.tv_usec + millis * 1000;
4393 if (usec >= 1000000) {
4394 abstime->tv_sec += 1;
4395 usec -= 1000000;
4396 }
4397 abstime->tv_nsec = usec * 1000;
4398 return abstime;
4399 }
4400
4401
4402 // Test-and-clear _Event, always leaves _Event set to 0, returns immediately.
4403 // Conceptually TryPark() should be equivalent to park(0).
4404
4405 int os::PlatformEvent::TryPark() {
4406 for (;;) {
4407 const int v = _Event ;
4408 guarantee ((v == 0) || (v == 1), "invariant") ;
4409 if (Atomic::cmpxchg (0, &_Event, v) == v) return v ;
4410 }
4411 }
4412
4413 void os::PlatformEvent::park() { // AKA "down()"
4414 // Invariant: Only the thread associated with the Event/PlatformEvent
4415 // may call park().
4416 // TODO: assert that _Assoc != NULL or _Assoc == Self
4417 int v ;
4418 for (;;) {
4419 v = _Event ;
4420 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ;
4421 }
4422 guarantee (v >= 0, "invariant") ;
4423 if (v == 0) {
4424 // Do this the hard way by blocking ...
4425 int status = pthread_mutex_lock(_mutex);
4426 assert_status(status == 0, status, "mutex_lock");
4427 guarantee (_nParked == 0, "invariant") ;
4428 ++ _nParked ;
4429 while (_Event < 0) {
4430 status = pthread_cond_wait(_cond, _mutex);
4431 // for some reason, under 2.7 lwp_cond_wait() may return ETIME ...
4432 // Treat this the same as if the wait was interrupted
4433 if (status == ETIME) { status = EINTR; }
4434 assert_status(status == 0 || status == EINTR, status, "cond_wait");
4435 }
4436 -- _nParked ;
4437
4438 // In theory we could move the ST of 0 into _Event past the unlock(),
4439 // but then we'd need a MEMBAR after the ST.
4440 _Event = 0 ;
4441 status = pthread_mutex_unlock(_mutex);
4442 assert_status(status == 0, status, "mutex_unlock");
4443 }
4444 guarantee (_Event >= 0, "invariant") ;
4445 }
4446
4447 int os::PlatformEvent::park(jlong millis) {
4448 guarantee (_nParked == 0, "invariant") ;
4449
4450 int v ;
4451 for (;;) {
4452 v = _Event ;
4453 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ;
4454 }
4455 guarantee (v >= 0, "invariant") ;
4456 if (v != 0) return OS_OK ;
4457
4458 // We do this the hard way, by blocking the thread.
4459 // Consider enforcing a minimum timeout value.
4460 struct timespec abst;
4461 compute_abstime(&abst, millis);
4462
4463 int ret = OS_TIMEOUT;
4464 int status = pthread_mutex_lock(_mutex);
4465 assert_status(status == 0, status, "mutex_lock");
4466 guarantee (_nParked == 0, "invariant") ;
4467 ++_nParked ;
4468
4469 // Object.wait(timo) will return because of
4470 // (a) notification
4471 // (b) timeout
4472 // (c) thread.interrupt
4473 //
4474 // Thread.interrupt and object.notify{All} both call Event::set.
4475 // That is, we treat thread.interrupt as a special case of notification.
4476 // The underlying Solaris implementation, cond_timedwait, admits
4477 // spurious/premature wakeups, but the JLS/JVM spec prevents the
4478 // JVM from making those visible to Java code. As such, we must
4479 // filter out spurious wakeups. We assume all ETIME returns are valid.
4480 //
4481 // TODO: properly differentiate simultaneous notify+interrupt.
4482 // In that case, we should propagate the notify to another waiter.
4483
4484 while (_Event < 0) {
4485 status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst);
4486 if (status != 0 && WorkAroundNPTLTimedWaitHang) {
4487 pthread_cond_destroy (_cond);
4488 pthread_cond_init (_cond, NULL) ;
4489 }
4490 assert_status(status == 0 || status == EINTR ||
4491 status == ETIME || status == ETIMEDOUT,
4492 status, "cond_timedwait");
4493 if (!FilterSpuriousWakeups) break ; // previous semantics
4494 if (status == ETIME || status == ETIMEDOUT) break ;
4495 // We consume and ignore EINTR and spurious wakeups.
4496 }
4497 --_nParked ;
4498 if (_Event >= 0) {
4499 ret = OS_OK;
4500 }
4501 _Event = 0 ;
4502 status = pthread_mutex_unlock(_mutex);
4503 assert_status(status == 0, status, "mutex_unlock");
4504 assert (_nParked == 0, "invariant") ;
4505 return ret;
4506 }
4507
4508 void os::PlatformEvent::unpark() {
4509 int v, AnyWaiters ;
4510 for (;;) {
4511 v = _Event ;
4512 if (v > 0) {
4513 // The LD of _Event could have reordered or be satisfied
4514 // by a read-aside from this processor's write buffer.
4515 // To avoid problems execute a barrier and then
4516 // ratify the value.
4517 OrderAccess::fence() ;
4518 if (_Event == v) return ;
4519 continue ;
4520 }
4521 if (Atomic::cmpxchg (v+1, &_Event, v) == v) break ;
4522 }
4523 if (v < 0) {
4524 // Wait for the thread associated with the event to vacate
4525 int status = pthread_mutex_lock(_mutex);
4526 assert_status(status == 0, status, "mutex_lock");
4527 AnyWaiters = _nParked ;
4528 assert (AnyWaiters == 0 || AnyWaiters == 1, "invariant") ;
4529 if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) {
4530 AnyWaiters = 0 ;
4531 pthread_cond_signal (_cond);
4532 }
4533 status = pthread_mutex_unlock(_mutex);
4534 assert_status(status == 0, status, "mutex_unlock");
4535 if (AnyWaiters != 0) {
4536 status = pthread_cond_signal(_cond);
4537 assert_status(status == 0, status, "cond_signal");
4538 }
4539 }
4540
4541 // Note that we signal() _after dropping the lock for "immortal" Events.
4542 // This is safe and avoids a common class of futile wakeups. In rare
4543 // circumstances this can cause a thread to return prematurely from
4544 // cond_{timed}wait() but the spurious wakeup is benign and the victim will
4545 // simply re-test the condition and re-park itself.
4546 }
4547
4548
4549 // JSR166
4550 // -------------------------------------------------------
4551
4552 /*
4553 * The solaris and linux implementations of park/unpark are fairly
4554 * conservative for now, but can be improved. They currently use a
4555 * mutex/condvar pair, plus a a count.
4556 * Park decrements count if > 0, else does a condvar wait. Unpark
4557 * sets count to 1 and signals condvar. Only one thread ever waits
4558 * on the condvar. Contention seen when trying to park implies that someone
4559 * is unparking you, so don't wait. And spurious returns are fine, so there
4560 * is no need to track notifications.
4561 */
4562
4563
4564 #define NANOSECS_PER_SEC 1000000000
4565 #define NANOSECS_PER_MILLISEC 1000000
4566 #define MAX_SECS 100000000
4567 /*
4568 * This code is common to linux and solaris and will be moved to a
4569 * common place in dolphin.
4570 *
4571 * The passed in time value is either a relative time in nanoseconds
4572 * or an absolute time in milliseconds. Either way it has to be unpacked
4573 * into suitable seconds and nanoseconds components and stored in the
4574 * given timespec structure.
4575 * Given time is a 64-bit value and the time_t used in the timespec is only
4576 * a signed-32-bit value (except on 64-bit Linux) we have to watch for
4577 * overflow if times way in the future are given. Further on Solaris versions
4578 * prior to 10 there is a restriction (see cond_timedwait) that the specified
4579 * number of seconds, in abstime, is less than current_time + 100,000,000.
4580 * As it will be 28 years before "now + 100000000" will overflow we can
4581 * ignore overflow and just impose a hard-limit on seconds using the value
4582 * of "now + 100,000,000". This places a limit on the timeout of about 3.17
4583 * years from "now".
4584 */
4585
4586 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) {
4587 assert (time > 0, "convertTime");
4588
4589 struct timeval now;
4590 int status = gettimeofday(&now, NULL);
4591 assert(status == 0, "gettimeofday");
4592
4593 time_t max_secs = now.tv_sec + MAX_SECS;
4594
4595 if (isAbsolute) {
4596 jlong secs = time / 1000;
4597 if (secs > max_secs) {
4598 absTime->tv_sec = max_secs;
4599 }
4600 else {
4601 absTime->tv_sec = secs;
4602 }
4603 absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC;
4604 }
4605 else {
4606 jlong secs = time / NANOSECS_PER_SEC;
4607 if (secs >= MAX_SECS) {
4608 absTime->tv_sec = max_secs;
4609 absTime->tv_nsec = 0;
4610 }
4611 else {
4612 absTime->tv_sec = now.tv_sec + secs;
4613 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000;
4614 if (absTime->tv_nsec >= NANOSECS_PER_SEC) {
4615 absTime->tv_nsec -= NANOSECS_PER_SEC;
4616 ++absTime->tv_sec; // note: this must be <= max_secs
4617 }
4618 }
4619 }
4620 assert(absTime->tv_sec >= 0, "tv_sec < 0");
4621 assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs");
4622 assert(absTime->tv_nsec >= 0, "tv_nsec < 0");
4623 assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec");
4624 }
4625
4626 void Parker::park(bool isAbsolute, jlong time) {
4627 // Optional fast-path check:
4628 // Return immediately if a permit is available.
4629 if (_counter > 0) {
4630 _counter = 0 ;
4631 return ;
4632 }
4633
4634 Thread* thread = Thread::current();
4635 assert(thread->is_Java_thread(), "Must be JavaThread");
4636 JavaThread *jt = (JavaThread *)thread;
4637
4638 // Optional optimization -- avoid state transitions if there's an interrupt pending.
4639 // Check interrupt before trying to wait
4640 if (Thread::is_interrupted(thread, false)) {
4641 return;
4642 }
4643
4644 // Next, demultiplex/decode time arguments
4645 timespec absTime;
4646 if (time < 0) { // don't wait at all
4647 return;
4648 }
4649 if (time > 0) {
4650 unpackTime(&absTime, isAbsolute, time);
4651 }
4652
4653
4654 // Enter safepoint region
4655 // Beware of deadlocks such as 6317397.
4656 // The per-thread Parker:: mutex is a classic leaf-lock.
4657 // In particular a thread must never block on the Threads_lock while
4658 // holding the Parker:: mutex. If safepoints are pending both the
4659 // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock.
4660 ThreadBlockInVM tbivm(jt);
4661
4662 // Don't wait if cannot get lock since interference arises from
4663 // unblocking. Also. check interrupt before trying wait
4664 if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) {
4665 return;
4666 }
4667
4668 int status ;
4669 if (_counter > 0) { // no wait needed
4670 _counter = 0;
4671 status = pthread_mutex_unlock(_mutex);
4672 assert (status == 0, "invariant") ;
4673 return;
4674 }
4675
4676 #ifdef ASSERT
4677 // Don't catch signals while blocked; let the running threads have the signals.
4678 // (This allows a debugger to break into the running thread.)
4679 sigset_t oldsigs;
4680 sigset_t* allowdebug_blocked = os::Linux::allowdebug_blocked_signals();
4681 pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs);
4682 #endif
4683
4684 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */);
4685 jt->set_suspend_equivalent();
4686 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
4687
4688 if (time == 0) {
4689 status = pthread_cond_wait (_cond, _mutex) ;
4690 } else {
4691 status = os::Linux::safe_cond_timedwait (_cond, _mutex, &absTime) ;
4692 if (status != 0 && WorkAroundNPTLTimedWaitHang) {
4693 pthread_cond_destroy (_cond) ;
4694 pthread_cond_init (_cond, NULL);
4695 }
4696 }
4697 assert_status(status == 0 || status == EINTR ||
4698 status == ETIME || status == ETIMEDOUT,
4699 status, "cond_timedwait");
4700
4701 #ifdef ASSERT
4702 pthread_sigmask(SIG_SETMASK, &oldsigs, NULL);
4703 #endif
4704
4705 _counter = 0 ;
4706 status = pthread_mutex_unlock(_mutex) ;
4707 assert_status(status == 0, status, "invariant") ;
4708 // If externally suspended while waiting, re-suspend
4709 if (jt->handle_special_suspend_equivalent_condition()) {
4710 jt->java_suspend_self();
4711 }
4712
4713 }
4714
4715 void Parker::unpark() {
4716 int s, status ;
4717 status = pthread_mutex_lock(_mutex);
4718 assert (status == 0, "invariant") ;
4719 s = _counter;
4720 _counter = 1;
4721 if (s < 1) {
4722 if (WorkAroundNPTLTimedWaitHang) {
4723 status = pthread_cond_signal (_cond) ;
4724 assert (status == 0, "invariant") ;
4725 status = pthread_mutex_unlock(_mutex);
4726 assert (status == 0, "invariant") ;
4727 } else {
4728 status = pthread_mutex_unlock(_mutex);
4729 assert (status == 0, "invariant") ;
4730 status = pthread_cond_signal (_cond) ;
4731 assert (status == 0, "invariant") ;
4732 }
4733 } else {
4734 pthread_mutex_unlock(_mutex);
4735 assert (status == 0, "invariant") ;
4736 }
4737 }
4738
4739
4740 extern char** environ;
4741
4742 #ifndef __NR_fork
4743 #define __NR_fork IA32_ONLY(2) IA64_ONLY(not defined) AMD64_ONLY(57)
4744 #endif
4745
4746 #ifndef __NR_execve
4747 #define __NR_execve IA32_ONLY(11) IA64_ONLY(1033) AMD64_ONLY(59)
4748 #endif
4749
4750 // Run the specified command in a separate process. Return its exit value,
4751 // or -1 on failure (e.g. can't fork a new process).
4752 // Unlike system(), this function can be called from signal handler. It
4753 // doesn't block SIGINT et al.
4754 int os::fork_and_exec(char* cmd) {
4755 const char * argv[4] = {"sh", "-c", cmd, NULL};
4756
4757 // fork() in LinuxThreads/NPTL is not async-safe. It needs to run
4758 // pthread_atfork handlers and reset pthread library. All we need is a
4759 // separate process to execve. Make a direct syscall to fork process.
4760 // On IA64 there's no fork syscall, we have to use fork() and hope for
4761 // the best...
4762 pid_t pid = NOT_IA64(syscall(__NR_fork);)
4763 IA64_ONLY(fork();)
4764
4765 if (pid < 0) {
4766 // fork failed
4767 return -1;
4768
4769 } else if (pid == 0) {
4770 // child process
4771
4772 // execve() in LinuxThreads will call pthread_kill_other_threads_np()
4773 // first to kill every thread on the thread list. Because this list is
4774 // not reset by fork() (see notes above), execve() will instead kill
4775 // every thread in the parent process. We know this is the only thread
4776 // in the new process, so make a system call directly.
4777 // IA64 should use normal execve() from glibc to match the glibc fork()
4778 // above.
4779 NOT_IA64(syscall(__NR_execve, "/bin/sh", argv, environ);)
4780 IA64_ONLY(execve("/bin/sh", (char* const*)argv, environ);)
4781
4782 // execve failed
4783 _exit(-1);
4784
4785 } else {
4786 // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't
4787 // care about the actual exit code, for now.
4788
4789 int status;
4790
4791 // Wait for the child process to exit. This returns immediately if
4792 // the child has already exited. */
4793 while (waitpid(pid, &status, 0) < 0) {
4794 switch (errno) {
4795 case ECHILD: return 0;
4796 case EINTR: break;
4797 default: return -1;
4798 }
4799 }
4800
4801 if (WIFEXITED(status)) {
4802 // The child exited normally; get its exit code.
4803 return WEXITSTATUS(status);
4804 } else if (WIFSIGNALED(status)) {
4805 // The child exited because of a signal
4806 // The best value to return is 0x80 + signal number,
4807 // because that is what all Unix shells do, and because
4808 // it allows callers to distinguish between process exit and
4809 // process death by signal.
4810 return 0x80 + WTERMSIG(status);
4811 } else {
4812 // Unknown exit code; pass it through
4813 return status;
4814 }
4815 }
4816 }