1 /*
2 * Copyright (c) 1999, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 // no precompiled headers
26 #include "classfile/classLoader.hpp"
27 #include "classfile/systemDictionary.hpp"
28 #include "classfile/vmSymbols.hpp"
29 #include "code/icBuffer.hpp"
30 #include "code/vtableStubs.hpp"
31 #include "compiler/compileBroker.hpp"
32 #include "compiler/disassembler.hpp"
33 #include "interpreter/interpreter.hpp"
34 #include "jvm_linux.h"
35 #include "memory/allocation.inline.hpp"
36 #include "memory/filemap.hpp"
37 #include "mutex_linux.inline.hpp"
38 #include "oops/oop.inline.hpp"
39 #include "os_share_linux.hpp"
40 #include "prims/jniFastGetField.hpp"
41 #include "prims/jvm.h"
42 #include "prims/jvm_misc.hpp"
43 #include "runtime/arguments.hpp"
44 #include "runtime/extendedPC.hpp"
45 #include "runtime/globals.hpp"
46 #include "runtime/interfaceSupport.hpp"
47 #include "runtime/java.hpp"
48 #include "runtime/javaCalls.hpp"
49 #include "runtime/mutexLocker.hpp"
50 #include "runtime/objectMonitor.hpp"
51 #include "runtime/osThread.hpp"
52 #include "runtime/perfMemory.hpp"
53 #include "runtime/sharedRuntime.hpp"
54 #include "runtime/statSampler.hpp"
55 #include "runtime/stubRoutines.hpp"
56 #include "runtime/thread.inline.hpp"
57 #include "runtime/threadCritical.hpp"
58 #include "runtime/timer.hpp"
59 #include "services/attachListener.hpp"
60 #include "services/runtimeService.hpp"
61 #include "utilities/decoder.hpp"
62 #include "utilities/defaultStream.hpp"
63 #include "utilities/events.hpp"
64 #include "utilities/growableArray.hpp"
65 #include "utilities/vmError.hpp"
66
67 // put OS-includes here
68 # include <sys/types.h>
69 # include <sys/mman.h>
70 # include <sys/stat.h>
71 # include <sys/select.h>
72 # include <pthread.h>
73 # include <signal.h>
74 # include <errno.h>
75 # include <dlfcn.h>
76 # include <stdio.h>
77 # include <unistd.h>
78 # include <sys/resource.h>
79 # include <pthread.h>
80 # include <sys/stat.h>
81 # include <sys/time.h>
82 # include <sys/times.h>
83 # include <sys/utsname.h>
84 # include <sys/socket.h>
85 # include <sys/wait.h>
86 # include <pwd.h>
87 # include <poll.h>
88 # include <semaphore.h>
89 # include <fcntl.h>
90 # include <string.h>
91 # include <syscall.h>
92 # include <sys/sysinfo.h>
93 # include <gnu/libc-version.h>
94 # include <sys/ipc.h>
95 # include <sys/shm.h>
96 # include <link.h>
97 # include <stdint.h>
98 # include <inttypes.h>
99 # include <sys/ioctl.h>
100
101 #define MAX_PATH (2 * K)
102
103 // for timer info max values which include all bits
104 #define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF)
105
106 #define LARGEPAGES_BIT (1 << 6)
107 ////////////////////////////////////////////////////////////////////////////////
108 // global variables
109 julong os::Linux::_physical_memory = 0;
110
111 address os::Linux::_initial_thread_stack_bottom = NULL;
112 uintptr_t os::Linux::_initial_thread_stack_size = 0;
113
114 int (*os::Linux::_clock_gettime)(clockid_t, struct timespec *) = NULL;
115 int (*os::Linux::_pthread_getcpuclockid)(pthread_t, clockid_t *) = NULL;
116 Mutex* os::Linux::_createThread_lock = NULL;
117 pthread_t os::Linux::_main_thread;
118 int os::Linux::_page_size = -1;
119 bool os::Linux::_is_floating_stack = false;
120 bool os::Linux::_is_NPTL = false;
121 bool os::Linux::_supports_fast_thread_cpu_time = false;
122 const char * os::Linux::_glibc_version = NULL;
123 const char * os::Linux::_libpthread_version = NULL;
124
125 static jlong initial_time_count=0;
126
127 static int clock_tics_per_sec = 100;
128
129 // For diagnostics to print a message once. see run_periodic_checks
130 static sigset_t check_signal_done;
131 static bool check_signals = true;;
132
133 static pid_t _initial_pid = 0;
134
135 /* Signal number used to suspend/resume a thread */
136
137 /* do not use any signal number less than SIGSEGV, see 4355769 */
138 static int SR_signum = SIGUSR2;
139 sigset_t SR_sigset;
140
141 /* Used to protect dlsym() calls */
142 static pthread_mutex_t dl_mutex;
143
144 #ifdef JAVASE_EMBEDDED
145 class MemNotifyThread: public Thread {
146 friend class VMStructs;
147 public:
148 virtual void run();
149
150 private:
151 static MemNotifyThread* _memnotify_thread;
152 int _fd;
153
154 public:
155
156 // Constructor
157 MemNotifyThread(int fd);
158
159 // Tester
160 bool is_memnotify_thread() const { return true; }
161
162 // Printing
163 char* name() const { return (char*)"Linux MemNotify Thread"; }
164
165 // Returns the single instance of the MemNotifyThread
166 static MemNotifyThread* memnotify_thread() { return _memnotify_thread; }
167
168 // Create and start the single instance of MemNotifyThread
169 static void start();
170 };
171 #endif // JAVASE_EMBEDDED
172
173 // utility functions
174
175 static int SR_initialize();
176 static int SR_finalize();
177
178 julong os::available_memory() {
179 return Linux::available_memory();
180 }
181
182 julong os::Linux::available_memory() {
183 // values in struct sysinfo are "unsigned long"
184 struct sysinfo si;
185 sysinfo(&si);
186
187 return (julong)si.freeram * si.mem_unit;
188 }
189
190 julong os::physical_memory() {
191 return Linux::physical_memory();
192 }
193
194 julong os::allocatable_physical_memory(julong size) {
195 #ifdef _LP64
196 return size;
197 #else
198 julong result = MIN2(size, (julong)3800*M);
199 if (!is_allocatable(result)) {
200 // See comments under solaris for alignment considerations
201 julong reasonable_size = (julong)2*G - 2 * os::vm_page_size();
202 result = MIN2(size, reasonable_size);
203 }
204 return result;
205 #endif // _LP64
206 }
207
208 ////////////////////////////////////////////////////////////////////////////////
209 // environment support
210
211 bool os::getenv(const char* name, char* buf, int len) {
212 const char* val = ::getenv(name);
213 if (val != NULL && strlen(val) < (size_t)len) {
214 strcpy(buf, val);
215 return true;
216 }
217 if (len > 0) buf[0] = 0; // return a null string
218 return false;
219 }
220
221
222 // Return true if user is running as root.
223
224 bool os::have_special_privileges() {
225 static bool init = false;
226 static bool privileges = false;
227 if (!init) {
228 privileges = (getuid() != geteuid()) || (getgid() != getegid());
229 init = true;
230 }
231 return privileges;
232 }
233
234
235 #ifndef SYS_gettid
236 // i386: 224, ia64: 1105, amd64: 186, sparc 143
237 #ifdef __ia64__
238 #define SYS_gettid 1105
239 #elif __i386__
240 #define SYS_gettid 224
241 #elif __amd64__
242 #define SYS_gettid 186
243 #elif __sparc__
244 #define SYS_gettid 143
245 #else
246 #error define gettid for the arch
247 #endif
248 #endif
249
250 // Cpu architecture string
251 #if defined(ZERO)
252 static char cpu_arch[] = ZERO_LIBARCH;
253 #elif defined(IA64)
254 static char cpu_arch[] = "ia64";
255 #elif defined(IA32)
256 static char cpu_arch[] = "i386";
257 #elif defined(AMD64)
258 static char cpu_arch[] = "amd64";
259 #elif defined(ARM)
260 static char cpu_arch[] = "arm";
261 #elif defined(PPC)
262 static char cpu_arch[] = "ppc";
263 #elif defined(SPARC)
264 # ifdef _LP64
265 static char cpu_arch[] = "sparcv9";
266 # else
267 static char cpu_arch[] = "sparc";
268 # endif
269 #else
270 #error Add appropriate cpu_arch setting
271 #endif
272
273
274 // pid_t gettid()
275 //
276 // Returns the kernel thread id of the currently running thread. Kernel
277 // thread id is used to access /proc.
278 //
279 // (Note that getpid() on LinuxThreads returns kernel thread id too; but
280 // on NPTL, it returns the same pid for all threads, as required by POSIX.)
281 //
282 pid_t os::Linux::gettid() {
283 int rslt = syscall(SYS_gettid);
284 if (rslt == -1) {
285 // old kernel, no NPTL support
286 return getpid();
287 } else {
288 return (pid_t)rslt;
289 }
290 }
291
292 // Most versions of linux have a bug where the number of processors are
293 // determined by looking at the /proc file system. In a chroot environment,
294 // the system call returns 1. This causes the VM to act as if it is
295 // a single processor and elide locking (see is_MP() call).
296 static bool unsafe_chroot_detected = false;
297 static const char *unstable_chroot_error = "/proc file system not found.\n"
298 "Java may be unstable running multithreaded in a chroot "
299 "environment on Linux when /proc filesystem is not mounted.";
300
301 void os::Linux::initialize_system_info() {
302 set_processor_count(sysconf(_SC_NPROCESSORS_CONF));
303 if (processor_count() == 1) {
304 pid_t pid = os::Linux::gettid();
305 char fname[32];
306 jio_snprintf(fname, sizeof(fname), "/proc/%d", pid);
307 FILE *fp = fopen(fname, "r");
308 if (fp == NULL) {
309 unsafe_chroot_detected = true;
310 } else {
311 fclose(fp);
312 }
313 }
314 _physical_memory = (julong)sysconf(_SC_PHYS_PAGES) * (julong)sysconf(_SC_PAGESIZE);
315 assert(processor_count() > 0, "linux error");
316 }
317
318 void os::init_system_properties_values() {
319 // char arch[12];
320 // sysinfo(SI_ARCHITECTURE, arch, sizeof(arch));
321
322 // The next steps are taken in the product version:
323 //
324 // Obtain the JAVA_HOME value from the location of libjvm.so.
325 // This library should be located at:
326 // <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm.so.
327 //
328 // If "/jre/lib/" appears at the right place in the path, then we
329 // assume libjvm.so is installed in a JDK and we use this path.
330 //
331 // Otherwise exit with message: "Could not create the Java virtual machine."
332 //
333 // The following extra steps are taken in the debugging version:
334 //
335 // If "/jre/lib/" does NOT appear at the right place in the path
336 // instead of exit check for $JAVA_HOME environment variable.
337 //
338 // If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>,
339 // then we append a fake suffix "hotspot/libjvm.so" to this path so
340 // it looks like libjvm.so is installed there
341 // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm.so.
342 //
343 // Otherwise exit.
344 //
345 // Important note: if the location of libjvm.so changes this
346 // code needs to be changed accordingly.
347
348 // The next few definitions allow the code to be verbatim:
349 #define malloc(n) (char*)NEW_C_HEAP_ARRAY(char, (n), mtInternal)
350 #define getenv(n) ::getenv(n)
351
352 /*
353 * See ld(1):
354 * The linker uses the following search paths to locate required
355 * shared libraries:
356 * 1: ...
357 * ...
358 * 7: The default directories, normally /lib and /usr/lib.
359 */
360 #if defined(AMD64) || defined(_LP64) && (defined(SPARC) || defined(PPC) || defined(S390))
361 #define DEFAULT_LIBPATH "/usr/lib64:/lib64:/lib:/usr/lib"
362 #else
363 #define DEFAULT_LIBPATH "/lib:/usr/lib"
364 #endif
365
366 #define EXTENSIONS_DIR "/lib/ext"
367 #define ENDORSED_DIR "/lib/endorsed"
368 #define REG_DIR "/usr/java/packages"
369
370 {
371 /* sysclasspath, java_home, dll_dir */
372 {
373 char *home_path;
374 char *dll_path;
375 char *pslash;
376 char buf[MAXPATHLEN];
377 os::jvm_path(buf, sizeof(buf));
378
379 // Found the full path to libjvm.so.
380 // Now cut the path to <java_home>/jre if we can.
381 *(strrchr(buf, '/')) = '\0'; /* get rid of /libjvm.so */
382 pslash = strrchr(buf, '/');
383 if (pslash != NULL)
384 *pslash = '\0'; /* get rid of /{client|server|hotspot} */
385 dll_path = malloc(strlen(buf) + 1);
386 if (dll_path == NULL)
387 return;
388 strcpy(dll_path, buf);
389 Arguments::set_dll_dir(dll_path);
390
391 if (pslash != NULL) {
392 pslash = strrchr(buf, '/');
393 if (pslash != NULL) {
394 *pslash = '\0'; /* get rid of /<arch> */
395 pslash = strrchr(buf, '/');
396 if (pslash != NULL)
397 *pslash = '\0'; /* get rid of /lib */
398 }
399 }
400
401 home_path = malloc(strlen(buf) + 1);
402 if (home_path == NULL)
403 return;
404 strcpy(home_path, buf);
405 Arguments::set_java_home(home_path);
406
407 if (!set_boot_path('/', ':'))
408 return;
409 }
410
411 /*
412 * Where to look for native libraries
413 *
414 * Note: Due to a legacy implementation, most of the library path
415 * is set in the launcher. This was to accomodate linking restrictions
416 * on legacy Linux implementations (which are no longer supported).
417 * Eventually, all the library path setting will be done here.
418 *
419 * However, to prevent the proliferation of improperly built native
420 * libraries, the new path component /usr/java/packages is added here.
421 * Eventually, all the library path setting will be done here.
422 */
423 {
424 char *ld_library_path;
425
426 /*
427 * Construct the invariant part of ld_library_path. Note that the
428 * space for the colon and the trailing null are provided by the
429 * nulls included by the sizeof operator (so actually we allocate
430 * a byte more than necessary).
431 */
432 ld_library_path = (char *) malloc(sizeof(REG_DIR) + sizeof("/lib/") +
433 strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH));
434 sprintf(ld_library_path, REG_DIR "/lib/%s:" DEFAULT_LIBPATH, cpu_arch);
435
436 /*
437 * Get the user setting of LD_LIBRARY_PATH, and prepended it. It
438 * should always exist (until the legacy problem cited above is
439 * addressed).
440 */
441 char *v = getenv("LD_LIBRARY_PATH");
442 if (v != NULL) {
443 char *t = ld_library_path;
444 /* That's +1 for the colon and +1 for the trailing '\0' */
445 ld_library_path = (char *) malloc(strlen(v) + 1 + strlen(t) + 1);
446 sprintf(ld_library_path, "%s:%s", v, t);
447 }
448 Arguments::set_library_path(ld_library_path);
449 }
450
451 /*
452 * Extensions directories.
453 *
454 * Note that the space for the colon and the trailing null are provided
455 * by the nulls included by the sizeof operator (so actually one byte more
456 * than necessary is allocated).
457 */
458 {
459 char *buf = malloc(strlen(Arguments::get_java_home()) +
460 sizeof(EXTENSIONS_DIR) + sizeof(REG_DIR) + sizeof(EXTENSIONS_DIR));
461 sprintf(buf, "%s" EXTENSIONS_DIR ":" REG_DIR EXTENSIONS_DIR,
462 Arguments::get_java_home());
463 Arguments::set_ext_dirs(buf);
464 }
465
466 /* Endorsed standards default directory. */
467 {
468 char * buf;
469 buf = malloc(strlen(Arguments::get_java_home()) + sizeof(ENDORSED_DIR));
470 sprintf(buf, "%s" ENDORSED_DIR, Arguments::get_java_home());
471 Arguments::set_endorsed_dirs(buf);
472 }
473 }
474
475 #undef malloc
476 #undef getenv
477 #undef EXTENSIONS_DIR
478 #undef ENDORSED_DIR
479
480 // Done
481 return;
482 }
483
484 ////////////////////////////////////////////////////////////////////////////////
485 // breakpoint support
486
487 void os::breakpoint() {
488 BREAKPOINT;
489 }
490
491 extern "C" void breakpoint() {
492 // use debugger to set breakpoint here
493 }
494
495 ////////////////////////////////////////////////////////////////////////////////
496 // signal support
497
498 debug_only(static bool signal_sets_initialized = false);
499 static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs;
500
501 bool os::Linux::is_sig_ignored(int sig) {
502 struct sigaction oact;
503 sigaction(sig, (struct sigaction*)NULL, &oact);
504 void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*, oact.sa_sigaction)
505 : CAST_FROM_FN_PTR(void*, oact.sa_handler);
506 if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN))
507 return true;
508 else
509 return false;
510 }
511
512 void os::Linux::signal_sets_init() {
513 // Should also have an assertion stating we are still single-threaded.
514 assert(!signal_sets_initialized, "Already initialized");
515 // Fill in signals that are necessarily unblocked for all threads in
516 // the VM. Currently, we unblock the following signals:
517 // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden
518 // by -Xrs (=ReduceSignalUsage));
519 // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all
520 // other threads. The "ReduceSignalUsage" boolean tells us not to alter
521 // the dispositions or masks wrt these signals.
522 // Programs embedding the VM that want to use the above signals for their
523 // own purposes must, at this time, use the "-Xrs" option to prevent
524 // interference with shutdown hooks and BREAK_SIGNAL thread dumping.
525 // (See bug 4345157, and other related bugs).
526 // In reality, though, unblocking these signals is really a nop, since
527 // these signals are not blocked by default.
528 sigemptyset(&unblocked_sigs);
529 sigemptyset(&allowdebug_blocked_sigs);
530 sigaddset(&unblocked_sigs, SIGILL);
531 sigaddset(&unblocked_sigs, SIGSEGV);
532 sigaddset(&unblocked_sigs, SIGBUS);
533 sigaddset(&unblocked_sigs, SIGFPE);
534 sigaddset(&unblocked_sigs, SR_signum);
535
536 if (!ReduceSignalUsage) {
537 if (!os::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) {
538 sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL);
539 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL);
540 }
541 if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) {
542 sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL);
543 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL);
544 }
545 if (!os::Linux::is_sig_ignored(SHUTDOWN3_SIGNAL)) {
546 sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL);
547 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN3_SIGNAL);
548 }
549 }
550 // Fill in signals that are blocked by all but the VM thread.
551 sigemptyset(&vm_sigs);
552 if (!ReduceSignalUsage)
553 sigaddset(&vm_sigs, BREAK_SIGNAL);
554 debug_only(signal_sets_initialized = true);
555
556 }
557
558 // These are signals that are unblocked while a thread is running Java.
559 // (For some reason, they get blocked by default.)
560 sigset_t* os::Linux::unblocked_signals() {
561 assert(signal_sets_initialized, "Not initialized");
562 return &unblocked_sigs;
563 }
564
565 // These are the signals that are blocked while a (non-VM) thread is
566 // running Java. Only the VM thread handles these signals.
567 sigset_t* os::Linux::vm_signals() {
568 assert(signal_sets_initialized, "Not initialized");
569 return &vm_sigs;
570 }
571
572 // These are signals that are blocked during cond_wait to allow debugger in
573 sigset_t* os::Linux::allowdebug_blocked_signals() {
574 assert(signal_sets_initialized, "Not initialized");
575 return &allowdebug_blocked_sigs;
576 }
577
578 void os::Linux::hotspot_sigmask(Thread* thread) {
579
580 //Save caller's signal mask before setting VM signal mask
581 sigset_t caller_sigmask;
582 pthread_sigmask(SIG_BLOCK, NULL, &caller_sigmask);
583
584 OSThread* osthread = thread->osthread();
585 osthread->set_caller_sigmask(caller_sigmask);
586
587 pthread_sigmask(SIG_UNBLOCK, os::Linux::unblocked_signals(), NULL);
588
589 if (!ReduceSignalUsage) {
590 if (thread->is_VM_thread()) {
591 // Only the VM thread handles BREAK_SIGNAL ...
592 pthread_sigmask(SIG_UNBLOCK, vm_signals(), NULL);
593 } else {
594 // ... all other threads block BREAK_SIGNAL
595 pthread_sigmask(SIG_BLOCK, vm_signals(), NULL);
596 }
597 }
598 }
599
600 //////////////////////////////////////////////////////////////////////////////
601 // detecting pthread library
602
603 void os::Linux::libpthread_init() {
604 // Save glibc and pthread version strings. Note that _CS_GNU_LIBC_VERSION
605 // and _CS_GNU_LIBPTHREAD_VERSION are supported in glibc >= 2.3.2. Use a
606 // generic name for earlier versions.
607 // Define macros here so we can build HotSpot on old systems.
608 # ifndef _CS_GNU_LIBC_VERSION
609 # define _CS_GNU_LIBC_VERSION 2
610 # endif
611 # ifndef _CS_GNU_LIBPTHREAD_VERSION
612 # define _CS_GNU_LIBPTHREAD_VERSION 3
613 # endif
614
615 size_t n = confstr(_CS_GNU_LIBC_VERSION, NULL, 0);
616 if (n > 0) {
617 char *str = (char *)malloc(n, mtInternal);
618 confstr(_CS_GNU_LIBC_VERSION, str, n);
619 os::Linux::set_glibc_version(str);
620 } else {
621 // _CS_GNU_LIBC_VERSION is not supported, try gnu_get_libc_version()
622 static char _gnu_libc_version[32];
623 jio_snprintf(_gnu_libc_version, sizeof(_gnu_libc_version),
624 "glibc %s %s", gnu_get_libc_version(), gnu_get_libc_release());
625 os::Linux::set_glibc_version(_gnu_libc_version);
626 }
627
628 n = confstr(_CS_GNU_LIBPTHREAD_VERSION, NULL, 0);
629 if (n > 0) {
630 char *str = (char *)malloc(n, mtInternal);
631 confstr(_CS_GNU_LIBPTHREAD_VERSION, str, n);
632 // Vanilla RH-9 (glibc 2.3.2) has a bug that confstr() always tells
633 // us "NPTL-0.29" even we are running with LinuxThreads. Check if this
634 // is the case. LinuxThreads has a hard limit on max number of threads.
635 // So sysconf(_SC_THREAD_THREADS_MAX) will return a positive value.
636 // On the other hand, NPTL does not have such a limit, sysconf()
637 // will return -1 and errno is not changed. Check if it is really NPTL.
638 if (strcmp(os::Linux::glibc_version(), "glibc 2.3.2") == 0 &&
639 strstr(str, "NPTL") &&
640 sysconf(_SC_THREAD_THREADS_MAX) > 0) {
641 free(str);
642 os::Linux::set_libpthread_version("linuxthreads");
643 } else {
644 os::Linux::set_libpthread_version(str);
645 }
646 } else {
647 // glibc before 2.3.2 only has LinuxThreads.
648 os::Linux::set_libpthread_version("linuxthreads");
649 }
650
651 if (strstr(libpthread_version(), "NPTL")) {
652 os::Linux::set_is_NPTL();
653 } else {
654 os::Linux::set_is_LinuxThreads();
655 }
656
657 // LinuxThreads have two flavors: floating-stack mode, which allows variable
658 // stack size; and fixed-stack mode. NPTL is always floating-stack.
659 if (os::Linux::is_NPTL() || os::Linux::supports_variable_stack_size()) {
660 os::Linux::set_is_floating_stack();
661 }
662 }
663
664 /////////////////////////////////////////////////////////////////////////////
665 // thread stack
666
667 // Force Linux kernel to expand current thread stack. If "bottom" is close
668 // to the stack guard, caller should block all signals.
669 //
670 // MAP_GROWSDOWN:
671 // A special mmap() flag that is used to implement thread stacks. It tells
672 // kernel that the memory region should extend downwards when needed. This
673 // allows early versions of LinuxThreads to only mmap the first few pages
674 // when creating a new thread. Linux kernel will automatically expand thread
675 // stack as needed (on page faults).
676 //
677 // However, because the memory region of a MAP_GROWSDOWN stack can grow on
678 // demand, if a page fault happens outside an already mapped MAP_GROWSDOWN
679 // region, it's hard to tell if the fault is due to a legitimate stack
680 // access or because of reading/writing non-exist memory (e.g. buffer
681 // overrun). As a rule, if the fault happens below current stack pointer,
682 // Linux kernel does not expand stack, instead a SIGSEGV is sent to the
683 // application (see Linux kernel fault.c).
684 //
685 // This Linux feature can cause SIGSEGV when VM bangs thread stack for
686 // stack overflow detection.
687 //
688 // Newer version of LinuxThreads (since glibc-2.2, or, RH-7.x) and NPTL do
689 // not use this flag. However, the stack of initial thread is not created
690 // by pthread, it is still MAP_GROWSDOWN. Also it's possible (though
691 // unlikely) that user code can create a thread with MAP_GROWSDOWN stack
692 // and then attach the thread to JVM.
693 //
694 // To get around the problem and allow stack banging on Linux, we need to
695 // manually expand thread stack after receiving the SIGSEGV.
696 //
697 // There are two ways to expand thread stack to address "bottom", we used
698 // both of them in JVM before 1.5:
699 // 1. adjust stack pointer first so that it is below "bottom", and then
700 // touch "bottom"
701 // 2. mmap() the page in question
702 //
703 // Now alternate signal stack is gone, it's harder to use 2. For instance,
704 // if current sp is already near the lower end of page 101, and we need to
705 // call mmap() to map page 100, it is possible that part of the mmap() frame
706 // will be placed in page 100. When page 100 is mapped, it is zero-filled.
707 // That will destroy the mmap() frame and cause VM to crash.
708 //
709 // The following code works by adjusting sp first, then accessing the "bottom"
710 // page to force a page fault. Linux kernel will then automatically expand the
711 // stack mapping.
712 //
713 // _expand_stack_to() assumes its frame size is less than page size, which
714 // should always be true if the function is not inlined.
715
716 #if __GNUC__ < 3 // gcc 2.x does not support noinline attribute
717 #define NOINLINE
718 #else
719 #define NOINLINE __attribute__ ((noinline))
720 #endif
721
722 static void _expand_stack_to(address bottom) NOINLINE;
723
724 static void _expand_stack_to(address bottom) {
725 address sp;
726 size_t size;
727 volatile char *p;
728
729 // Adjust bottom to point to the largest address within the same page, it
730 // gives us a one-page buffer if alloca() allocates slightly more memory.
731 bottom = (address)align_size_down((uintptr_t)bottom, os::Linux::page_size());
732 bottom += os::Linux::page_size() - 1;
733
734 // sp might be slightly above current stack pointer; if that's the case, we
735 // will alloca() a little more space than necessary, which is OK. Don't use
736 // os::current_stack_pointer(), as its result can be slightly below current
737 // stack pointer, causing us to not alloca enough to reach "bottom".
738 sp = (address)&sp;
739
740 if (sp > bottom) {
741 size = sp - bottom;
742 p = (volatile char *)alloca(size);
743 assert(p != NULL && p <= (volatile char *)bottom, "alloca problem?");
744 p[0] = '\0';
745 }
746 }
747
748 bool os::Linux::manually_expand_stack(JavaThread * t, address addr) {
749 assert(t!=NULL, "just checking");
750 assert(t->osthread()->expanding_stack(), "expand should be set");
751 assert(t->stack_base() != NULL, "stack_base was not initialized");
752
753 if (addr < t->stack_base() && addr >= t->stack_yellow_zone_base()) {
754 sigset_t mask_all, old_sigset;
755 sigfillset(&mask_all);
756 pthread_sigmask(SIG_SETMASK, &mask_all, &old_sigset);
757 _expand_stack_to(addr);
758 pthread_sigmask(SIG_SETMASK, &old_sigset, NULL);
759 return true;
760 }
761 return false;
762 }
763
764 //////////////////////////////////////////////////////////////////////////////
765 // create new thread
766
767 static address highest_vm_reserved_address();
768
769 // check if it's safe to start a new thread
770 static bool _thread_safety_check(Thread* thread) {
771 if (os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack()) {
772 // Fixed stack LinuxThreads (SuSE Linux/x86, and some versions of Redhat)
773 // Heap is mmap'ed at lower end of memory space. Thread stacks are
774 // allocated (MAP_FIXED) from high address space. Every thread stack
775 // occupies a fixed size slot (usually 2Mbytes, but user can change
776 // it to other values if they rebuild LinuxThreads).
777 //
778 // Problem with MAP_FIXED is that mmap() can still succeed even part of
779 // the memory region has already been mmap'ed. That means if we have too
780 // many threads and/or very large heap, eventually thread stack will
781 // collide with heap.
782 //
783 // Here we try to prevent heap/stack collision by comparing current
784 // stack bottom with the highest address that has been mmap'ed by JVM
785 // plus a safety margin for memory maps created by native code.
786 //
787 // This feature can be disabled by setting ThreadSafetyMargin to 0
788 //
789 if (ThreadSafetyMargin > 0) {
790 address stack_bottom = os::current_stack_base() - os::current_stack_size();
791
792 // not safe if our stack extends below the safety margin
793 return stack_bottom - ThreadSafetyMargin >= highest_vm_reserved_address();
794 } else {
795 return true;
796 }
797 } else {
798 // Floating stack LinuxThreads or NPTL:
799 // Unlike fixed stack LinuxThreads, thread stacks are not MAP_FIXED. When
800 // there's not enough space left, pthread_create() will fail. If we come
801 // here, that means enough space has been reserved for stack.
802 return true;
803 }
804 }
805
806 // Thread start routine for all newly created threads
807 static void *java_start(Thread *thread) {
808 // Try to randomize the cache line index of hot stack frames.
809 // This helps when threads of the same stack traces evict each other's
810 // cache lines. The threads can be either from the same JVM instance, or
811 // from different JVM instances. The benefit is especially true for
812 // processors with hyperthreading technology.
813 static int counter = 0;
814 int pid = os::current_process_id();
815 alloca(((pid ^ counter++) & 7) * 128);
816
817 ThreadLocalStorage::set_thread(thread);
818
819 OSThread* osthread = thread->osthread();
820 Monitor* sync = osthread->startThread_lock();
821
822 // non floating stack LinuxThreads needs extra check, see above
823 if (!_thread_safety_check(thread)) {
824 // notify parent thread
825 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
826 osthread->set_state(ZOMBIE);
827 sync->notify_all();
828 return NULL;
829 }
830
831 // thread_id is kernel thread id (similar to Solaris LWP id)
832 osthread->set_thread_id(os::Linux::gettid());
833
834 if (UseNUMA) {
835 int lgrp_id = os::numa_get_group_id();
836 if (lgrp_id != -1) {
837 thread->set_lgrp_id(lgrp_id);
838 }
839 }
840 // initialize signal mask for this thread
841 os::Linux::hotspot_sigmask(thread);
842
843 // initialize floating point control register
844 os::Linux::init_thread_fpu_state();
845
846 // handshaking with parent thread
847 {
848 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
849
850 // notify parent thread
851 osthread->set_state(INITIALIZED);
852 sync->notify_all();
853
854 // wait until os::start_thread()
855 while (osthread->get_state() == INITIALIZED) {
856 sync->wait(Mutex::_no_safepoint_check_flag);
857 }
858 }
859
860 // call one more level start routine
861 thread->run();
862
863 return 0;
864 }
865
866 bool os::create_thread(Thread* thread, ThreadType thr_type, size_t stack_size) {
867 assert(thread->osthread() == NULL, "caller responsible");
868
869 // Allocate the OSThread object
870 OSThread* osthread = new OSThread(NULL, NULL);
871 if (osthread == NULL) {
872 return false;
873 }
874
875 // set the correct thread state
876 osthread->set_thread_type(thr_type);
877
878 // Initial state is ALLOCATED but not INITIALIZED
879 osthread->set_state(ALLOCATED);
880
881 thread->set_osthread(osthread);
882
883 // init thread attributes
884 pthread_attr_t attr;
885 pthread_attr_init(&attr);
886 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
887
888 // stack size
889 if (os::Linux::supports_variable_stack_size()) {
890 // calculate stack size if it's not specified by caller
891 if (stack_size == 0) {
892 stack_size = os::Linux::default_stack_size(thr_type);
893
894 switch (thr_type) {
895 case os::java_thread:
896 // Java threads use ThreadStackSize which default value can be
897 // changed with the flag -Xss
898 assert (JavaThread::stack_size_at_create() > 0, "this should be set");
899 stack_size = JavaThread::stack_size_at_create();
900 break;
901 case os::compiler_thread:
902 if (CompilerThreadStackSize > 0) {
903 stack_size = (size_t)(CompilerThreadStackSize * K);
904 break;
905 } // else fall through:
906 // use VMThreadStackSize if CompilerThreadStackSize is not defined
907 case os::vm_thread:
908 case os::pgc_thread:
909 case os::cgc_thread:
910 case os::watcher_thread:
911 if (VMThreadStackSize > 0) stack_size = (size_t)(VMThreadStackSize * K);
912 break;
913 }
914 }
915
916 stack_size = MAX2(stack_size, os::Linux::min_stack_allowed);
917 pthread_attr_setstacksize(&attr, stack_size);
918 } else {
919 // let pthread_create() pick the default value.
920 }
921
922 // glibc guard page
923 pthread_attr_setguardsize(&attr, os::Linux::default_guard_size(thr_type));
924
925 ThreadState state;
926
927 {
928 // Serialize thread creation if we are running with fixed stack LinuxThreads
929 bool lock = os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack();
930 if (lock) {
931 os::Linux::createThread_lock()->lock_without_safepoint_check();
932 }
933
934 pthread_t tid;
935 int ret = pthread_create(&tid, &attr, (void* (*)(void*)) java_start, thread);
936
937 pthread_attr_destroy(&attr);
938
939 if (ret != 0) {
940 if (PrintMiscellaneous && (Verbose || WizardMode)) {
941 perror("pthread_create()");
942 }
943 // Need to clean up stuff we've allocated so far
944 thread->set_osthread(NULL);
945 delete osthread;
946 if (lock) os::Linux::createThread_lock()->unlock();
947 return false;
948 }
949
950 // Store pthread info into the OSThread
951 osthread->set_pthread_id(tid);
952
953 // Wait until child thread is either initialized or aborted
954 {
955 Monitor* sync_with_child = osthread->startThread_lock();
956 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
957 while ((state = osthread->get_state()) == ALLOCATED) {
958 sync_with_child->wait(Mutex::_no_safepoint_check_flag);
959 }
960 }
961
962 if (lock) {
963 os::Linux::createThread_lock()->unlock();
964 }
965 }
966
967 // Aborted due to thread limit being reached
968 if (state == ZOMBIE) {
969 thread->set_osthread(NULL);
970 delete osthread;
971 return false;
972 }
973
974 // The thread is returned suspended (in state INITIALIZED),
975 // and is started higher up in the call chain
976 assert(state == INITIALIZED, "race condition");
977 return true;
978 }
979
980 /////////////////////////////////////////////////////////////////////////////
981 // attach existing thread
982
983 // bootstrap the main thread
984 bool os::create_main_thread(JavaThread* thread) {
985 assert(os::Linux::_main_thread == pthread_self(), "should be called inside main thread");
986 return create_attached_thread(thread);
987 }
988
989 bool os::create_attached_thread(JavaThread* thread) {
990 #ifdef ASSERT
991 thread->verify_not_published();
992 #endif
993
994 // Allocate the OSThread object
995 OSThread* osthread = new OSThread(NULL, NULL);
996
997 if (osthread == NULL) {
998 return false;
999 }
1000
1001 // Store pthread info into the OSThread
1002 osthread->set_thread_id(os::Linux::gettid());
1003 osthread->set_pthread_id(::pthread_self());
1004
1005 // initialize floating point control register
1006 os::Linux::init_thread_fpu_state();
1007
1008 // Initial thread state is RUNNABLE
1009 osthread->set_state(RUNNABLE);
1010
1011 thread->set_osthread(osthread);
1012
1013 if (UseNUMA) {
1014 int lgrp_id = os::numa_get_group_id();
1015 if (lgrp_id != -1) {
1016 thread->set_lgrp_id(lgrp_id);
1017 }
1018 }
1019
1020 if (os::Linux::is_initial_thread()) {
1021 // If current thread is initial thread, its stack is mapped on demand,
1022 // see notes about MAP_GROWSDOWN. Here we try to force kernel to map
1023 // the entire stack region to avoid SEGV in stack banging.
1024 // It is also useful to get around the heap-stack-gap problem on SuSE
1025 // kernel (see 4821821 for details). We first expand stack to the top
1026 // of yellow zone, then enable stack yellow zone (order is significant,
1027 // enabling yellow zone first will crash JVM on SuSE Linux), so there
1028 // is no gap between the last two virtual memory regions.
1029
1030 JavaThread *jt = (JavaThread *)thread;
1031 address addr = jt->stack_yellow_zone_base();
1032 assert(addr != NULL, "initialization problem?");
1033 assert(jt->stack_available(addr) > 0, "stack guard should not be enabled");
1034
1035 osthread->set_expanding_stack();
1036 os::Linux::manually_expand_stack(jt, addr);
1037 osthread->clear_expanding_stack();
1038 }
1039
1040 // initialize signal mask for this thread
1041 // and save the caller's signal mask
1042 os::Linux::hotspot_sigmask(thread);
1043
1044 return true;
1045 }
1046
1047 void os::pd_start_thread(Thread* thread) {
1048 OSThread * osthread = thread->osthread();
1049 assert(osthread->get_state() != INITIALIZED, "just checking");
1050 Monitor* sync_with_child = osthread->startThread_lock();
1051 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
1052 sync_with_child->notify();
1053 }
1054
1055 // Free Linux resources related to the OSThread
1056 void os::free_thread(OSThread* osthread) {
1057 assert(osthread != NULL, "osthread not set");
1058
1059 if (Thread::current()->osthread() == osthread) {
1060 // Restore caller's signal mask
1061 sigset_t sigmask = osthread->caller_sigmask();
1062 pthread_sigmask(SIG_SETMASK, &sigmask, NULL);
1063 }
1064
1065 delete osthread;
1066 }
1067
1068 //////////////////////////////////////////////////////////////////////////////
1069 // thread local storage
1070
1071 int os::allocate_thread_local_storage() {
1072 pthread_key_t key;
1073 int rslt = pthread_key_create(&key, NULL);
1074 assert(rslt == 0, "cannot allocate thread local storage");
1075 return (int)key;
1076 }
1077
1078 // Note: This is currently not used by VM, as we don't destroy TLS key
1079 // on VM exit.
1080 void os::free_thread_local_storage(int index) {
1081 int rslt = pthread_key_delete((pthread_key_t)index);
1082 assert(rslt == 0, "invalid index");
1083 }
1084
1085 void os::thread_local_storage_at_put(int index, void* value) {
1086 int rslt = pthread_setspecific((pthread_key_t)index, value);
1087 assert(rslt == 0, "pthread_setspecific failed");
1088 }
1089
1090 extern "C" Thread* get_thread() {
1091 return ThreadLocalStorage::thread();
1092 }
1093
1094 //////////////////////////////////////////////////////////////////////////////
1095 // initial thread
1096
1097 // Check if current thread is the initial thread, similar to Solaris thr_main.
1098 bool os::Linux::is_initial_thread(void) {
1099 char dummy;
1100 // If called before init complete, thread stack bottom will be null.
1101 // Can be called if fatal error occurs before initialization.
1102 if (initial_thread_stack_bottom() == NULL) return false;
1103 assert(initial_thread_stack_bottom() != NULL &&
1104 initial_thread_stack_size() != 0,
1105 "os::init did not locate initial thread's stack region");
1106 if ((address)&dummy >= initial_thread_stack_bottom() &&
1107 (address)&dummy < initial_thread_stack_bottom() + initial_thread_stack_size())
1108 return true;
1109 else return false;
1110 }
1111
1112 // Find the virtual memory area that contains addr
1113 static bool find_vma(address addr, address* vma_low, address* vma_high) {
1114 FILE *fp = fopen("/proc/self/maps", "r");
1115 if (fp) {
1116 address low, high;
1117 while (!feof(fp)) {
1118 if (fscanf(fp, "%p-%p", &low, &high) == 2) {
1119 if (low <= addr && addr < high) {
1120 if (vma_low) *vma_low = low;
1121 if (vma_high) *vma_high = high;
1122 fclose (fp);
1123 return true;
1124 }
1125 }
1126 for (;;) {
1127 int ch = fgetc(fp);
1128 if (ch == EOF || ch == (int)'\n') break;
1129 }
1130 }
1131 fclose(fp);
1132 }
1133 return false;
1134 }
1135
1136 // Locate initial thread stack. This special handling of initial thread stack
1137 // is needed because pthread_getattr_np() on most (all?) Linux distros returns
1138 // bogus value for initial thread.
1139 void os::Linux::capture_initial_stack(size_t max_size) {
1140 // stack size is the easy part, get it from RLIMIT_STACK
1141 size_t stack_size;
1142 struct rlimit rlim;
1143 getrlimit(RLIMIT_STACK, &rlim);
1144 stack_size = rlim.rlim_cur;
1145
1146 // 6308388: a bug in ld.so will relocate its own .data section to the
1147 // lower end of primordial stack; reduce ulimit -s value a little bit
1148 // so we won't install guard page on ld.so's data section.
1149 stack_size -= 2 * page_size();
1150
1151 // 4441425: avoid crash with "unlimited" stack size on SuSE 7.1 or Redhat
1152 // 7.1, in both cases we will get 2G in return value.
1153 // 4466587: glibc 2.2.x compiled w/o "--enable-kernel=2.4.0" (RH 7.0,
1154 // SuSE 7.2, Debian) can not handle alternate signal stack correctly
1155 // for initial thread if its stack size exceeds 6M. Cap it at 2M,
1156 // in case other parts in glibc still assumes 2M max stack size.
1157 // FIXME: alt signal stack is gone, maybe we can relax this constraint?
1158 // Problem still exists RH7.2 (IA64 anyway) but 2MB is a little small
1159 if (stack_size > 2 * K * K IA64_ONLY(*2))
1160 stack_size = 2 * K * K IA64_ONLY(*2);
1161 // Try to figure out where the stack base (top) is. This is harder.
1162 //
1163 // When an application is started, glibc saves the initial stack pointer in
1164 // a global variable "__libc_stack_end", which is then used by system
1165 // libraries. __libc_stack_end should be pretty close to stack top. The
1166 // variable is available since the very early days. However, because it is
1167 // a private interface, it could disappear in the future.
1168 //
1169 // Linux kernel saves start_stack information in /proc/<pid>/stat. Similar
1170 // to __libc_stack_end, it is very close to stack top, but isn't the real
1171 // stack top. Note that /proc may not exist if VM is running as a chroot
1172 // program, so reading /proc/<pid>/stat could fail. Also the contents of
1173 // /proc/<pid>/stat could change in the future (though unlikely).
1174 //
1175 // We try __libc_stack_end first. If that doesn't work, look for
1176 // /proc/<pid>/stat. If neither of them works, we use current stack pointer
1177 // as a hint, which should work well in most cases.
1178
1179 uintptr_t stack_start;
1180
1181 // try __libc_stack_end first
1182 uintptr_t *p = (uintptr_t *)dlsym(RTLD_DEFAULT, "__libc_stack_end");
1183 if (p && *p) {
1184 stack_start = *p;
1185 } else {
1186 // see if we can get the start_stack field from /proc/self/stat
1187 FILE *fp;
1188 int pid;
1189 char state;
1190 int ppid;
1191 int pgrp;
1192 int session;
1193 int nr;
1194 int tpgrp;
1195 unsigned long flags;
1196 unsigned long minflt;
1197 unsigned long cminflt;
1198 unsigned long majflt;
1199 unsigned long cmajflt;
1200 unsigned long utime;
1201 unsigned long stime;
1202 long cutime;
1203 long cstime;
1204 long prio;
1205 long nice;
1206 long junk;
1207 long it_real;
1208 uintptr_t start;
1209 uintptr_t vsize;
1210 intptr_t rss;
1211 uintptr_t rsslim;
1212 uintptr_t scodes;
1213 uintptr_t ecode;
1214 int i;
1215
1216 // Figure what the primordial thread stack base is. Code is inspired
1217 // by email from Hans Boehm. /proc/self/stat begins with current pid,
1218 // followed by command name surrounded by parentheses, state, etc.
1219 char stat[2048];
1220 int statlen;
1221
1222 fp = fopen("/proc/self/stat", "r");
1223 if (fp) {
1224 statlen = fread(stat, 1, 2047, fp);
1225 stat[statlen] = '\0';
1226 fclose(fp);
1227
1228 // Skip pid and the command string. Note that we could be dealing with
1229 // weird command names, e.g. user could decide to rename java launcher
1230 // to "java 1.4.2 :)", then the stat file would look like
1231 // 1234 (java 1.4.2 :)) R ... ...
1232 // We don't really need to know the command string, just find the last
1233 // occurrence of ")" and then start parsing from there. See bug 4726580.
1234 char * s = strrchr(stat, ')');
1235
1236 i = 0;
1237 if (s) {
1238 // Skip blank chars
1239 do s++; while (isspace(*s));
1240
1241 #define _UFM UINTX_FORMAT
1242 #define _DFM INTX_FORMAT
1243
1244 /* 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 */
1245 /* 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 */
1246 i = sscanf(s, "%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu %ld %ld %ld %ld %ld %ld " _UFM _UFM _DFM _UFM _UFM _UFM _UFM,
1247 &state, /* 3 %c */
1248 &ppid, /* 4 %d */
1249 &pgrp, /* 5 %d */
1250 &session, /* 6 %d */
1251 &nr, /* 7 %d */
1252 &tpgrp, /* 8 %d */
1253 &flags, /* 9 %lu */
1254 &minflt, /* 10 %lu */
1255 &cminflt, /* 11 %lu */
1256 &majflt, /* 12 %lu */
1257 &cmajflt, /* 13 %lu */
1258 &utime, /* 14 %lu */
1259 &stime, /* 15 %lu */
1260 &cutime, /* 16 %ld */
1261 &cstime, /* 17 %ld */
1262 &prio, /* 18 %ld */
1263 &nice, /* 19 %ld */
1264 &junk, /* 20 %ld */
1265 &it_real, /* 21 %ld */
1266 &start, /* 22 UINTX_FORMAT */
1267 &vsize, /* 23 UINTX_FORMAT */
1268 &rss, /* 24 INTX_FORMAT */
1269 &rsslim, /* 25 UINTX_FORMAT */
1270 &scodes, /* 26 UINTX_FORMAT */
1271 &ecode, /* 27 UINTX_FORMAT */
1272 &stack_start); /* 28 UINTX_FORMAT */
1273 }
1274
1275 #undef _UFM
1276 #undef _DFM
1277
1278 if (i != 28 - 2) {
1279 assert(false, "Bad conversion from /proc/self/stat");
1280 // product mode - assume we are the initial thread, good luck in the
1281 // embedded case.
1282 warning("Can't detect initial thread stack location - bad conversion");
1283 stack_start = (uintptr_t) &rlim;
1284 }
1285 } else {
1286 // For some reason we can't open /proc/self/stat (for example, running on
1287 // FreeBSD with a Linux emulator, or inside chroot), this should work for
1288 // most cases, so don't abort:
1289 warning("Can't detect initial thread stack location - no /proc/self/stat");
1290 stack_start = (uintptr_t) &rlim;
1291 }
1292 }
1293
1294 // Now we have a pointer (stack_start) very close to the stack top, the
1295 // next thing to do is to figure out the exact location of stack top. We
1296 // can find out the virtual memory area that contains stack_start by
1297 // reading /proc/self/maps, it should be the last vma in /proc/self/maps,
1298 // and its upper limit is the real stack top. (again, this would fail if
1299 // running inside chroot, because /proc may not exist.)
1300
1301 uintptr_t stack_top;
1302 address low, high;
1303 if (find_vma((address)stack_start, &low, &high)) {
1304 // success, "high" is the true stack top. (ignore "low", because initial
1305 // thread stack grows on demand, its real bottom is high - RLIMIT_STACK.)
1306 stack_top = (uintptr_t)high;
1307 } else {
1308 // failed, likely because /proc/self/maps does not exist
1309 warning("Can't detect initial thread stack location - find_vma failed");
1310 // best effort: stack_start is normally within a few pages below the real
1311 // stack top, use it as stack top, and reduce stack size so we won't put
1312 // guard page outside stack.
1313 stack_top = stack_start;
1314 stack_size -= 16 * page_size();
1315 }
1316
1317 // stack_top could be partially down the page so align it
1318 stack_top = align_size_up(stack_top, page_size());
1319
1320 if (max_size && stack_size > max_size) {
1321 _initial_thread_stack_size = max_size;
1322 } else {
1323 _initial_thread_stack_size = stack_size;
1324 }
1325
1326 _initial_thread_stack_size = align_size_down(_initial_thread_stack_size, page_size());
1327 _initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size;
1328 }
1329
1330 ////////////////////////////////////////////////////////////////////////////////
1331 // time support
1332
1333 // Time since start-up in seconds to a fine granularity.
1334 // Used by VMSelfDestructTimer and the MemProfiler.
1335 double os::elapsedTime() {
1336
1337 return (double)(os::elapsed_counter()) * 0.000001;
1338 }
1339
1340 jlong os::elapsed_counter() {
1341 timeval time;
1342 int status = gettimeofday(&time, NULL);
1343 return jlong(time.tv_sec) * 1000 * 1000 + jlong(time.tv_usec) - initial_time_count;
1344 }
1345
1346 jlong os::elapsed_frequency() {
1347 return (1000 * 1000);
1348 }
1349
1350 // For now, we say that linux does not support vtime. I have no idea
1351 // whether it can actually be made to (DLD, 9/13/05).
1352
1353 bool os::supports_vtime() { return false; }
1354 bool os::enable_vtime() { return false; }
1355 bool os::vtime_enabled() { return false; }
1356 double os::elapsedVTime() {
1357 // better than nothing, but not much
1358 return elapsedTime();
1359 }
1360
1361 jlong os::javaTimeMillis() {
1362 timeval time;
1363 int status = gettimeofday(&time, NULL);
1364 assert(status != -1, "linux error");
1365 return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000);
1366 }
1367
1368 #ifndef CLOCK_MONOTONIC
1369 #define CLOCK_MONOTONIC (1)
1370 #endif
1371
1372 void os::Linux::clock_init() {
1373 // we do dlopen's in this particular order due to bug in linux
1374 // dynamical loader (see 6348968) leading to crash on exit
1375 void* handle = dlopen("librt.so.1", RTLD_LAZY);
1376 if (handle == NULL) {
1377 handle = dlopen("librt.so", RTLD_LAZY);
1378 }
1379
1380 if (handle) {
1381 int (*clock_getres_func)(clockid_t, struct timespec*) =
1382 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres");
1383 int (*clock_gettime_func)(clockid_t, struct timespec*) =
1384 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime");
1385 if (clock_getres_func && clock_gettime_func) {
1386 // See if monotonic clock is supported by the kernel. Note that some
1387 // early implementations simply return kernel jiffies (updated every
1388 // 1/100 or 1/1000 second). It would be bad to use such a low res clock
1389 // for nano time (though the monotonic property is still nice to have).
1390 // It's fixed in newer kernels, however clock_getres() still returns
1391 // 1/HZ. We check if clock_getres() works, but will ignore its reported
1392 // resolution for now. Hopefully as people move to new kernels, this
1393 // won't be a problem.
1394 struct timespec res;
1395 struct timespec tp;
1396 if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 &&
1397 clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) {
1398 // yes, monotonic clock is supported
1399 _clock_gettime = clock_gettime_func;
1400 } else {
1401 // close librt if there is no monotonic clock
1402 dlclose(handle);
1403 }
1404 }
1405 }
1406 }
1407
1408 #ifndef SYS_clock_getres
1409
1410 #if defined(IA32) || defined(AMD64)
1411 #define SYS_clock_getres IA32_ONLY(266) AMD64_ONLY(229)
1412 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y)
1413 #else
1414 #warning "SYS_clock_getres not defined for this platform, disabling fast_thread_cpu_time"
1415 #define sys_clock_getres(x,y) -1
1416 #endif
1417
1418 #else
1419 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y)
1420 #endif
1421
1422 void os::Linux::fast_thread_clock_init() {
1423 if (!UseLinuxPosixThreadCPUClocks) {
1424 return;
1425 }
1426 clockid_t clockid;
1427 struct timespec tp;
1428 int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) =
1429 (int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid");
1430
1431 // Switch to using fast clocks for thread cpu time if
1432 // the sys_clock_getres() returns 0 error code.
1433 // Note, that some kernels may support the current thread
1434 // clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks
1435 // returned by the pthread_getcpuclockid().
1436 // If the fast Posix clocks are supported then the sys_clock_getres()
1437 // must return at least tp.tv_sec == 0 which means a resolution
1438 // better than 1 sec. This is extra check for reliability.
1439
1440 if(pthread_getcpuclockid_func &&
1441 pthread_getcpuclockid_func(_main_thread, &clockid) == 0 &&
1442 sys_clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) {
1443
1444 _supports_fast_thread_cpu_time = true;
1445 _pthread_getcpuclockid = pthread_getcpuclockid_func;
1446 }
1447 }
1448
1449 jlong os::javaTimeNanos() {
1450 if (Linux::supports_monotonic_clock()) {
1451 struct timespec tp;
1452 int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp);
1453 assert(status == 0, "gettime error");
1454 jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec);
1455 return result;
1456 } else {
1457 timeval time;
1458 int status = gettimeofday(&time, NULL);
1459 assert(status != -1, "linux error");
1460 jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec);
1461 return 1000 * usecs;
1462 }
1463 }
1464
1465 void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) {
1466 if (Linux::supports_monotonic_clock()) {
1467 info_ptr->max_value = ALL_64_BITS;
1468
1469 // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past
1470 info_ptr->may_skip_backward = false; // not subject to resetting or drifting
1471 info_ptr->may_skip_forward = false; // not subject to resetting or drifting
1472 } else {
1473 // gettimeofday - based on time in seconds since the Epoch thus does not wrap
1474 info_ptr->max_value = ALL_64_BITS;
1475
1476 // gettimeofday is a real time clock so it skips
1477 info_ptr->may_skip_backward = true;
1478 info_ptr->may_skip_forward = true;
1479 }
1480
1481 info_ptr->kind = JVMTI_TIMER_ELAPSED; // elapsed not CPU time
1482 }
1483
1484 // Return the real, user, and system times in seconds from an
1485 // arbitrary fixed point in the past.
1486 bool os::getTimesSecs(double* process_real_time,
1487 double* process_user_time,
1488 double* process_system_time) {
1489 struct tms ticks;
1490 clock_t real_ticks = times(&ticks);
1491
1492 if (real_ticks == (clock_t) (-1)) {
1493 return false;
1494 } else {
1495 double ticks_per_second = (double) clock_tics_per_sec;
1496 *process_user_time = ((double) ticks.tms_utime) / ticks_per_second;
1497 *process_system_time = ((double) ticks.tms_stime) / ticks_per_second;
1498 *process_real_time = ((double) real_ticks) / ticks_per_second;
1499
1500 return true;
1501 }
1502 }
1503
1504
1505 char * os::local_time_string(char *buf, size_t buflen) {
1506 struct tm t;
1507 time_t long_time;
1508 time(&long_time);
1509 localtime_r(&long_time, &t);
1510 jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d",
1511 t.tm_year + 1900, t.tm_mon + 1, t.tm_mday,
1512 t.tm_hour, t.tm_min, t.tm_sec);
1513 return buf;
1514 }
1515
1516 struct tm* os::localtime_pd(const time_t* clock, struct tm* res) {
1517 return localtime_r(clock, res);
1518 }
1519
1520 ////////////////////////////////////////////////////////////////////////////////
1521 // runtime exit support
1522
1523 // Note: os::shutdown() might be called very early during initialization, or
1524 // called from signal handler. Before adding something to os::shutdown(), make
1525 // sure it is async-safe and can handle partially initialized VM.
1526 void os::shutdown() {
1527
1528 // allow PerfMemory to attempt cleanup of any persistent resources
1529 perfMemory_exit();
1530
1531 // needs to remove object in file system
1532 AttachListener::abort();
1533
1534 // flush buffered output, finish log files
1535 ostream_abort();
1536
1537 // Check for abort hook
1538 abort_hook_t abort_hook = Arguments::abort_hook();
1539 if (abort_hook != NULL) {
1540 abort_hook();
1541 }
1542
1543 }
1544
1545 // Note: os::abort() might be called very early during initialization, or
1546 // called from signal handler. Before adding something to os::abort(), make
1547 // sure it is async-safe and can handle partially initialized VM.
1548 void os::abort(bool dump_core) {
1549 os::shutdown();
1550 if (dump_core) {
1551 #ifndef PRODUCT
1552 fdStream out(defaultStream::output_fd());
1553 out.print_raw("Current thread is ");
1554 char buf[16];
1555 jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id());
1556 out.print_raw_cr(buf);
1557 out.print_raw_cr("Dumping core ...");
1558 #endif
1559 ::abort(); // dump core
1560 }
1561
1562 ::exit(1);
1563 }
1564
1565 // Die immediately, no exit hook, no abort hook, no cleanup.
1566 void os::die() {
1567 // _exit() on LinuxThreads only kills current thread
1568 ::abort();
1569 }
1570
1571 // unused on linux for now.
1572 void os::set_error_file(const char *logfile) {}
1573
1574
1575 // This method is a copy of JDK's sysGetLastErrorString
1576 // from src/solaris/hpi/src/system_md.c
1577
1578 size_t os::lasterror(char *buf, size_t len) {
1579
1580 if (errno == 0) return 0;
1581
1582 const char *s = ::strerror(errno);
1583 size_t n = ::strlen(s);
1584 if (n >= len) {
1585 n = len - 1;
1586 }
1587 ::strncpy(buf, s, n);
1588 buf[n] = '\0';
1589 return n;
1590 }
1591
1592 intx os::current_thread_id() { return (intx)pthread_self(); }
1593 int os::current_process_id() {
1594
1595 // Under the old linux thread library, linux gives each thread
1596 // its own process id. Because of this each thread will return
1597 // a different pid if this method were to return the result
1598 // of getpid(2). Linux provides no api that returns the pid
1599 // of the launcher thread for the vm. This implementation
1600 // returns a unique pid, the pid of the launcher thread
1601 // that starts the vm 'process'.
1602
1603 // Under the NPTL, getpid() returns the same pid as the
1604 // launcher thread rather than a unique pid per thread.
1605 // Use gettid() if you want the old pre NPTL behaviour.
1606
1607 // if you are looking for the result of a call to getpid() that
1608 // returns a unique pid for the calling thread, then look at the
1609 // OSThread::thread_id() method in osThread_linux.hpp file
1610
1611 return (int)(_initial_pid ? _initial_pid : getpid());
1612 }
1613
1614 // DLL functions
1615
1616 const char* os::dll_file_extension() { return ".so"; }
1617
1618 // This must be hard coded because it's the system's temporary
1619 // directory not the java application's temp directory, ala java.io.tmpdir.
1620 const char* os::get_temp_directory() { return "/tmp"; }
1621
1622 static bool file_exists(const char* filename) {
1623 struct stat statbuf;
1624 if (filename == NULL || strlen(filename) == 0) {
1625 return false;
1626 }
1627 return os::stat(filename, &statbuf) == 0;
1628 }
1629
1630 bool os::dll_build_name(char* buffer, size_t buflen,
1631 const char* pname, const char* fname) {
1632 bool retval = false;
1633 // Copied from libhpi
1634 const size_t pnamelen = pname ? strlen(pname) : 0;
1635
1636 // Return error on buffer overflow.
1637 if (pnamelen + strlen(fname) + 10 > (size_t) buflen) {
1638 return retval;
1639 }
1640
1641 if (pnamelen == 0) {
1642 snprintf(buffer, buflen, "lib%s.so", fname);
1643 retval = true;
1644 } else if (strchr(pname, *os::path_separator()) != NULL) {
1645 int n;
1646 char** pelements = split_path(pname, &n);
1647 for (int i = 0 ; i < n ; i++) {
1648 // Really shouldn't be NULL, but check can't hurt
1649 if (pelements[i] == NULL || strlen(pelements[i]) == 0) {
1650 continue; // skip the empty path values
1651 }
1652 snprintf(buffer, buflen, "%s/lib%s.so", pelements[i], fname);
1653 if (file_exists(buffer)) {
1654 retval = true;
1655 break;
1656 }
1657 }
1658 // release the storage
1659 for (int i = 0 ; i < n ; i++) {
1660 if (pelements[i] != NULL) {
1661 FREE_C_HEAP_ARRAY(char, pelements[i], mtInternal);
1662 }
1663 }
1664 if (pelements != NULL) {
1665 FREE_C_HEAP_ARRAY(char*, pelements, mtInternal);
1666 }
1667 } else {
1668 snprintf(buffer, buflen, "%s/lib%s.so", pname, fname);
1669 retval = true;
1670 }
1671 return retval;
1672 }
1673
1674 const char* os::get_current_directory(char *buf, int buflen) {
1675 return getcwd(buf, buflen);
1676 }
1677
1678 // check if addr is inside libjvm.so
1679 bool os::address_is_in_vm(address addr) {
1680 static address libjvm_base_addr;
1681 Dl_info dlinfo;
1682
1683 if (libjvm_base_addr == NULL) {
1684 dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo);
1685 libjvm_base_addr = (address)dlinfo.dli_fbase;
1686 assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm");
1687 }
1688
1689 if (dladdr((void *)addr, &dlinfo)) {
1690 if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true;
1691 }
1692
1693 return false;
1694 }
1695
1696 bool os::dll_address_to_function_name(address addr, char *buf,
1697 int buflen, int *offset) {
1698 Dl_info dlinfo;
1699
1700 if (dladdr((void*)addr, &dlinfo) && dlinfo.dli_sname != NULL) {
1701 if (buf != NULL) {
1702 if(!Decoder::demangle(dlinfo.dli_sname, buf, buflen)) {
1703 jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname);
1704 }
1705 }
1706 if (offset != NULL) *offset = addr - (address)dlinfo.dli_saddr;
1707 return true;
1708 } else if (dlinfo.dli_fname != NULL && dlinfo.dli_fbase != 0) {
1709 if (Decoder::decode((address)(addr - (address)dlinfo.dli_fbase),
1710 buf, buflen, offset, dlinfo.dli_fname)) {
1711 return true;
1712 }
1713 }
1714
1715 if (buf != NULL) buf[0] = '\0';
1716 if (offset != NULL) *offset = -1;
1717 return false;
1718 }
1719
1720 struct _address_to_library_name {
1721 address addr; // input : memory address
1722 size_t buflen; // size of fname
1723 char* fname; // output: library name
1724 address base; // library base addr
1725 };
1726
1727 static int address_to_library_name_callback(struct dl_phdr_info *info,
1728 size_t size, void *data) {
1729 int i;
1730 bool found = false;
1731 address libbase = NULL;
1732 struct _address_to_library_name * d = (struct _address_to_library_name *)data;
1733
1734 // iterate through all loadable segments
1735 for (i = 0; i < info->dlpi_phnum; i++) {
1736 address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr);
1737 if (info->dlpi_phdr[i].p_type == PT_LOAD) {
1738 // base address of a library is the lowest address of its loaded
1739 // segments.
1740 if (libbase == NULL || libbase > segbase) {
1741 libbase = segbase;
1742 }
1743 // see if 'addr' is within current segment
1744 if (segbase <= d->addr &&
1745 d->addr < segbase + info->dlpi_phdr[i].p_memsz) {
1746 found = true;
1747 }
1748 }
1749 }
1750
1751 // dlpi_name is NULL or empty if the ELF file is executable, return 0
1752 // so dll_address_to_library_name() can fall through to use dladdr() which
1753 // can figure out executable name from argv[0].
1754 if (found && info->dlpi_name && info->dlpi_name[0]) {
1755 d->base = libbase;
1756 if (d->fname) {
1757 jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name);
1758 }
1759 return 1;
1760 }
1761 return 0;
1762 }
1763
1764 bool os::dll_address_to_library_name(address addr, char* buf,
1765 int buflen, int* offset) {
1766 Dl_info dlinfo;
1767 struct _address_to_library_name data;
1768
1769 // There is a bug in old glibc dladdr() implementation that it could resolve
1770 // to wrong library name if the .so file has a base address != NULL. Here
1771 // we iterate through the program headers of all loaded libraries to find
1772 // out which library 'addr' really belongs to. This workaround can be
1773 // removed once the minimum requirement for glibc is moved to 2.3.x.
1774 data.addr = addr;
1775 data.fname = buf;
1776 data.buflen = buflen;
1777 data.base = NULL;
1778 int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data);
1779
1780 if (rslt) {
1781 // buf already contains library name
1782 if (offset) *offset = addr - data.base;
1783 return true;
1784 } else if (dladdr((void*)addr, &dlinfo)){
1785 if (buf) jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname);
1786 if (offset) *offset = addr - (address)dlinfo.dli_fbase;
1787 return true;
1788 } else {
1789 if (buf) buf[0] = '\0';
1790 if (offset) *offset = -1;
1791 return false;
1792 }
1793 }
1794
1795 // Loads .dll/.so and
1796 // in case of error it checks if .dll/.so was built for the
1797 // same architecture as Hotspot is running on
1798
1799 void * os::dll_load(const char *filename, char *ebuf, int ebuflen)
1800 {
1801 void * result= ::dlopen(filename, RTLD_LAZY);
1802 if (result != NULL) {
1803 // Successful loading
1804 return result;
1805 }
1806
1807 Elf32_Ehdr elf_head;
1808
1809 // Read system error message into ebuf
1810 // It may or may not be overwritten below
1811 ::strncpy(ebuf, ::dlerror(), ebuflen-1);
1812 ebuf[ebuflen-1]='\0';
1813 int diag_msg_max_length=ebuflen-strlen(ebuf);
1814 char* diag_msg_buf=ebuf+strlen(ebuf);
1815
1816 if (diag_msg_max_length==0) {
1817 // No more space in ebuf for additional diagnostics message
1818 return NULL;
1819 }
1820
1821
1822 int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK);
1823
1824 if (file_descriptor < 0) {
1825 // Can't open library, report dlerror() message
1826 return NULL;
1827 }
1828
1829 bool failed_to_read_elf_head=
1830 (sizeof(elf_head)!=
1831 (::read(file_descriptor, &elf_head,sizeof(elf_head)))) ;
1832
1833 ::close(file_descriptor);
1834 if (failed_to_read_elf_head) {
1835 // file i/o error - report dlerror() msg
1836 return NULL;
1837 }
1838
1839 typedef struct {
1840 Elf32_Half code; // Actual value as defined in elf.h
1841 Elf32_Half compat_class; // Compatibility of archs at VM's sense
1842 char elf_class; // 32 or 64 bit
1843 char endianess; // MSB or LSB
1844 char* name; // String representation
1845 } arch_t;
1846
1847 #ifndef EM_486
1848 #define EM_486 6 /* Intel 80486 */
1849 #endif
1850
1851 static const arch_t arch_array[]={
1852 {EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
1853 {EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
1854 {EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"},
1855 {EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"},
1856 {EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
1857 {EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
1858 {EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"},
1859 {EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"},
1860 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"},
1861 {EM_ARM, EM_ARM, ELFCLASS32, ELFDATA2LSB, (char*)"ARM"},
1862 {EM_S390, EM_S390, ELFCLASSNONE, ELFDATA2MSB, (char*)"IBM System/390"},
1863 {EM_ALPHA, EM_ALPHA, ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"},
1864 {EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"},
1865 {EM_MIPS, EM_MIPS, ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"},
1866 {EM_PARISC, EM_PARISC, ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"},
1867 {EM_68K, EM_68K, ELFCLASS32, ELFDATA2MSB, (char*)"M68k"}
1868 };
1869
1870 #if (defined IA32)
1871 static Elf32_Half running_arch_code=EM_386;
1872 #elif (defined AMD64)
1873 static Elf32_Half running_arch_code=EM_X86_64;
1874 #elif (defined IA64)
1875 static Elf32_Half running_arch_code=EM_IA_64;
1876 #elif (defined __sparc) && (defined _LP64)
1877 static Elf32_Half running_arch_code=EM_SPARCV9;
1878 #elif (defined __sparc) && (!defined _LP64)
1879 static Elf32_Half running_arch_code=EM_SPARC;
1880 #elif (defined __powerpc64__)
1881 static Elf32_Half running_arch_code=EM_PPC64;
1882 #elif (defined __powerpc__)
1883 static Elf32_Half running_arch_code=EM_PPC;
1884 #elif (defined ARM)
1885 static Elf32_Half running_arch_code=EM_ARM;
1886 #elif (defined S390)
1887 static Elf32_Half running_arch_code=EM_S390;
1888 #elif (defined ALPHA)
1889 static Elf32_Half running_arch_code=EM_ALPHA;
1890 #elif (defined MIPSEL)
1891 static Elf32_Half running_arch_code=EM_MIPS_RS3_LE;
1892 #elif (defined PARISC)
1893 static Elf32_Half running_arch_code=EM_PARISC;
1894 #elif (defined MIPS)
1895 static Elf32_Half running_arch_code=EM_MIPS;
1896 #elif (defined M68K)
1897 static Elf32_Half running_arch_code=EM_68K;
1898 #else
1899 #error Method os::dll_load requires that one of following is defined:\
1900 IA32, AMD64, IA64, __sparc, __powerpc__, ARM, S390, ALPHA, MIPS, MIPSEL, PARISC, M68K
1901 #endif
1902
1903 // Identify compatability class for VM's architecture and library's architecture
1904 // Obtain string descriptions for architectures
1905
1906 arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL};
1907 int running_arch_index=-1;
1908
1909 for (unsigned int i=0 ; i < ARRAY_SIZE(arch_array) ; i++ ) {
1910 if (running_arch_code == arch_array[i].code) {
1911 running_arch_index = i;
1912 }
1913 if (lib_arch.code == arch_array[i].code) {
1914 lib_arch.compat_class = arch_array[i].compat_class;
1915 lib_arch.name = arch_array[i].name;
1916 }
1917 }
1918
1919 assert(running_arch_index != -1,
1920 "Didn't find running architecture code (running_arch_code) in arch_array");
1921 if (running_arch_index == -1) {
1922 // Even though running architecture detection failed
1923 // we may still continue with reporting dlerror() message
1924 return NULL;
1925 }
1926
1927 if (lib_arch.endianess != arch_array[running_arch_index].endianess) {
1928 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)");
1929 return NULL;
1930 }
1931
1932 #ifndef S390
1933 if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) {
1934 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)");
1935 return NULL;
1936 }
1937 #endif // !S390
1938
1939 if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) {
1940 if ( lib_arch.name!=NULL ) {
1941 ::snprintf(diag_msg_buf, diag_msg_max_length-1,
1942 " (Possible cause: can't load %s-bit .so on a %s-bit platform)",
1943 lib_arch.name, arch_array[running_arch_index].name);
1944 } else {
1945 ::snprintf(diag_msg_buf, diag_msg_max_length-1,
1946 " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)",
1947 lib_arch.code,
1948 arch_array[running_arch_index].name);
1949 }
1950 }
1951
1952 return NULL;
1953 }
1954
1955 /*
1956 * glibc-2.0 libdl is not MT safe. If you are building with any glibc,
1957 * chances are you might want to run the generated bits against glibc-2.0
1958 * libdl.so, so always use locking for any version of glibc.
1959 */
1960 void* os::dll_lookup(void* handle, const char* name) {
1961 pthread_mutex_lock(&dl_mutex);
1962 void* res = dlsym(handle, name);
1963 pthread_mutex_unlock(&dl_mutex);
1964 return res;
1965 }
1966
1967
1968 static bool _print_ascii_file(const char* filename, outputStream* st) {
1969 int fd = ::open(filename, O_RDONLY);
1970 if (fd == -1) {
1971 return false;
1972 }
1973
1974 char buf[32];
1975 int bytes;
1976 while ((bytes = ::read(fd, buf, sizeof(buf))) > 0) {
1977 st->print_raw(buf, bytes);
1978 }
1979
1980 ::close(fd);
1981
1982 return true;
1983 }
1984
1985 void os::print_dll_info(outputStream *st) {
1986 st->print_cr("Dynamic libraries:");
1987
1988 char fname[32];
1989 pid_t pid = os::Linux::gettid();
1990
1991 jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid);
1992
1993 if (!_print_ascii_file(fname, st)) {
1994 st->print("Can not get library information for pid = %d\n", pid);
1995 }
1996 }
1997
1998 void os::print_os_info_brief(outputStream* st) {
1999 os::Linux::print_distro_info(st);
2000
2001 os::Posix::print_uname_info(st);
2002
2003 os::Linux::print_libversion_info(st);
2004
2005 }
2006
2007 void os::print_os_info(outputStream* st) {
2008 st->print("OS:");
2009
2010 os::Linux::print_distro_info(st);
2011
2012 os::Posix::print_uname_info(st);
2013
2014 // Print warning if unsafe chroot environment detected
2015 if (unsafe_chroot_detected) {
2016 st->print("WARNING!! ");
2017 st->print_cr(unstable_chroot_error);
2018 }
2019
2020 os::Linux::print_libversion_info(st);
2021
2022 os::Posix::print_rlimit_info(st);
2023
2024 os::Posix::print_load_average(st);
2025
2026 os::Linux::print_full_memory_info(st);
2027 }
2028
2029 // Try to identify popular distros.
2030 // Most Linux distributions have /etc/XXX-release file, which contains
2031 // the OS version string. Some have more than one /etc/XXX-release file
2032 // (e.g. Mandrake has both /etc/mandrake-release and /etc/redhat-release.),
2033 // so the order is important.
2034 void os::Linux::print_distro_info(outputStream* st) {
2035 if (!_print_ascii_file("/etc/mandrake-release", st) &&
2036 !_print_ascii_file("/etc/sun-release", st) &&
2037 !_print_ascii_file("/etc/redhat-release", st) &&
2038 !_print_ascii_file("/etc/SuSE-release", st) &&
2039 !_print_ascii_file("/etc/turbolinux-release", st) &&
2040 !_print_ascii_file("/etc/gentoo-release", st) &&
2041 !_print_ascii_file("/etc/debian_version", st) &&
2042 !_print_ascii_file("/etc/ltib-release", st) &&
2043 !_print_ascii_file("/etc/angstrom-version", st)) {
2044 st->print("Linux");
2045 }
2046 st->cr();
2047 }
2048
2049 void os::Linux::print_libversion_info(outputStream* st) {
2050 // libc, pthread
2051 st->print("libc:");
2052 st->print(os::Linux::glibc_version()); st->print(" ");
2053 st->print(os::Linux::libpthread_version()); st->print(" ");
2054 if (os::Linux::is_LinuxThreads()) {
2055 st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed");
2056 }
2057 st->cr();
2058 }
2059
2060 void os::Linux::print_full_memory_info(outputStream* st) {
2061 st->print("\n/proc/meminfo:\n");
2062 _print_ascii_file("/proc/meminfo", st);
2063 st->cr();
2064 }
2065
2066 void os::print_memory_info(outputStream* st) {
2067
2068 st->print("Memory:");
2069 st->print(" %dk page", os::vm_page_size()>>10);
2070
2071 // values in struct sysinfo are "unsigned long"
2072 struct sysinfo si;
2073 sysinfo(&si);
2074
2075 st->print(", physical " UINT64_FORMAT "k",
2076 os::physical_memory() >> 10);
2077 st->print("(" UINT64_FORMAT "k free)",
2078 os::available_memory() >> 10);
2079 st->print(", swap " UINT64_FORMAT "k",
2080 ((jlong)si.totalswap * si.mem_unit) >> 10);
2081 st->print("(" UINT64_FORMAT "k free)",
2082 ((jlong)si.freeswap * si.mem_unit) >> 10);
2083 st->cr();
2084 }
2085
2086 void os::pd_print_cpu_info(outputStream* st) {
2087 st->print("\n/proc/cpuinfo:\n");
2088 if (!_print_ascii_file("/proc/cpuinfo", st)) {
2089 st->print(" <Not Available>");
2090 }
2091 st->cr();
2092 }
2093
2094 // Taken from /usr/include/bits/siginfo.h Supposed to be architecture specific
2095 // but they're the same for all the linux arch that we support
2096 // and they're the same for solaris but there's no common place to put this.
2097 const char *ill_names[] = { "ILL0", "ILL_ILLOPC", "ILL_ILLOPN", "ILL_ILLADR",
2098 "ILL_ILLTRP", "ILL_PRVOPC", "ILL_PRVREG",
2099 "ILL_COPROC", "ILL_BADSTK" };
2100
2101 const char *fpe_names[] = { "FPE0", "FPE_INTDIV", "FPE_INTOVF", "FPE_FLTDIV",
2102 "FPE_FLTOVF", "FPE_FLTUND", "FPE_FLTRES",
2103 "FPE_FLTINV", "FPE_FLTSUB", "FPE_FLTDEN" };
2104
2105 const char *segv_names[] = { "SEGV0", "SEGV_MAPERR", "SEGV_ACCERR" };
2106
2107 const char *bus_names[] = { "BUS0", "BUS_ADRALN", "BUS_ADRERR", "BUS_OBJERR" };
2108
2109 void os::print_siginfo(outputStream* st, void* siginfo) {
2110 st->print("siginfo:");
2111
2112 const int buflen = 100;
2113 char buf[buflen];
2114 siginfo_t *si = (siginfo_t*)siginfo;
2115 st->print("si_signo=%s: ", os::exception_name(si->si_signo, buf, buflen));
2116 if (si->si_errno != 0 && strerror_r(si->si_errno, buf, buflen) == 0) {
2117 st->print("si_errno=%s", buf);
2118 } else {
2119 st->print("si_errno=%d", si->si_errno);
2120 }
2121 const int c = si->si_code;
2122 assert(c > 0, "unexpected si_code");
2123 switch (si->si_signo) {
2124 case SIGILL:
2125 st->print(", si_code=%d (%s)", c, c > 8 ? "" : ill_names[c]);
2126 st->print(", si_addr=" PTR_FORMAT, si->si_addr);
2127 break;
2128 case SIGFPE:
2129 st->print(", si_code=%d (%s)", c, c > 9 ? "" : fpe_names[c]);
2130 st->print(", si_addr=" PTR_FORMAT, si->si_addr);
2131 break;
2132 case SIGSEGV:
2133 st->print(", si_code=%d (%s)", c, c > 2 ? "" : segv_names[c]);
2134 st->print(", si_addr=" PTR_FORMAT, si->si_addr);
2135 break;
2136 case SIGBUS:
2137 st->print(", si_code=%d (%s)", c, c > 3 ? "" : bus_names[c]);
2138 st->print(", si_addr=" PTR_FORMAT, si->si_addr);
2139 break;
2140 default:
2141 st->print(", si_code=%d", si->si_code);
2142 // no si_addr
2143 }
2144
2145 if ((si->si_signo == SIGBUS || si->si_signo == SIGSEGV) &&
2146 UseSharedSpaces) {
2147 FileMapInfo* mapinfo = FileMapInfo::current_info();
2148 if (mapinfo->is_in_shared_space(si->si_addr)) {
2149 st->print("\n\nError accessing class data sharing archive." \
2150 " Mapped file inaccessible during execution, " \
2151 " possible disk/network problem.");
2152 }
2153 }
2154 st->cr();
2155 }
2156
2157
2158 static void print_signal_handler(outputStream* st, int sig,
2159 char* buf, size_t buflen);
2160
2161 void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) {
2162 st->print_cr("Signal Handlers:");
2163 print_signal_handler(st, SIGSEGV, buf, buflen);
2164 print_signal_handler(st, SIGBUS , buf, buflen);
2165 print_signal_handler(st, SIGFPE , buf, buflen);
2166 print_signal_handler(st, SIGPIPE, buf, buflen);
2167 print_signal_handler(st, SIGXFSZ, buf, buflen);
2168 print_signal_handler(st, SIGILL , buf, buflen);
2169 print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen);
2170 print_signal_handler(st, SR_signum, buf, buflen);
2171 print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen);
2172 print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen);
2173 print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen);
2174 print_signal_handler(st, BREAK_SIGNAL, buf, buflen);
2175 }
2176
2177 static char saved_jvm_path[MAXPATHLEN] = {0};
2178
2179 // Find the full path to the current module, libjvm.so
2180 void os::jvm_path(char *buf, jint buflen) {
2181 // Error checking.
2182 if (buflen < MAXPATHLEN) {
2183 assert(false, "must use a large-enough buffer");
2184 buf[0] = '\0';
2185 return;
2186 }
2187 // Lazy resolve the path to current module.
2188 if (saved_jvm_path[0] != 0) {
2189 strcpy(buf, saved_jvm_path);
2190 return;
2191 }
2192
2193 char dli_fname[MAXPATHLEN];
2194 bool ret = dll_address_to_library_name(
2195 CAST_FROM_FN_PTR(address, os::jvm_path),
2196 dli_fname, sizeof(dli_fname), NULL);
2197 assert(ret != 0, "cannot locate libjvm");
2198 char *rp = realpath(dli_fname, buf);
2199 if (rp == NULL)
2200 return;
2201
2202 if (Arguments::created_by_gamma_launcher()) {
2203 // Support for the gamma launcher. Typical value for buf is
2204 // "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so". If "/jre/lib/" appears at
2205 // the right place in the string, then assume we are installed in a JDK and
2206 // we're done. Otherwise, check for a JAVA_HOME environment variable and fix
2207 // up the path so it looks like libjvm.so is installed there (append a
2208 // fake suffix hotspot/libjvm.so).
2209 const char *p = buf + strlen(buf) - 1;
2210 for (int count = 0; p > buf && count < 5; ++count) {
2211 for (--p; p > buf && *p != '/'; --p)
2212 /* empty */ ;
2213 }
2214
2215 if (strncmp(p, "/jre/lib/", 9) != 0) {
2216 // Look for JAVA_HOME in the environment.
2217 char* java_home_var = ::getenv("JAVA_HOME");
2218 if (java_home_var != NULL && java_home_var[0] != 0) {
2219 char* jrelib_p;
2220 int len;
2221
2222 // Check the current module name "libjvm.so".
2223 p = strrchr(buf, '/');
2224 assert(strstr(p, "/libjvm") == p, "invalid library name");
2225
2226 rp = realpath(java_home_var, buf);
2227 if (rp == NULL)
2228 return;
2229
2230 // determine if this is a legacy image or modules image
2231 // modules image doesn't have "jre" subdirectory
2232 len = strlen(buf);
2233 jrelib_p = buf + len;
2234 snprintf(jrelib_p, buflen-len, "/jre/lib/%s", cpu_arch);
2235 if (0 != access(buf, F_OK)) {
2236 snprintf(jrelib_p, buflen-len, "/lib/%s", cpu_arch);
2237 }
2238
2239 if (0 == access(buf, F_OK)) {
2240 // Use current module name "libjvm.so"
2241 len = strlen(buf);
2242 snprintf(buf + len, buflen-len, "/hotspot/libjvm.so");
2243 } else {
2244 // Go back to path of .so
2245 rp = realpath(dli_fname, buf);
2246 if (rp == NULL)
2247 return;
2248 }
2249 }
2250 }
2251 }
2252
2253 strcpy(saved_jvm_path, buf);
2254 }
2255
2256 void os::print_jni_name_prefix_on(outputStream* st, int args_size) {
2257 // no prefix required, not even "_"
2258 }
2259
2260 void os::print_jni_name_suffix_on(outputStream* st, int args_size) {
2261 // no suffix required
2262 }
2263
2264 ////////////////////////////////////////////////////////////////////////////////
2265 // sun.misc.Signal support
2266
2267 static volatile jint sigint_count = 0;
2268
2269 static void
2270 UserHandler(int sig, void *siginfo, void *context) {
2271 // 4511530 - sem_post is serialized and handled by the manager thread. When
2272 // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We
2273 // don't want to flood the manager thread with sem_post requests.
2274 if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1)
2275 return;
2276
2277 // Ctrl-C is pressed during error reporting, likely because the error
2278 // handler fails to abort. Let VM die immediately.
2279 if (sig == SIGINT && is_error_reported()) {
2280 os::die();
2281 }
2282
2283 os::signal_notify(sig);
2284 }
2285
2286 void* os::user_handler() {
2287 return CAST_FROM_FN_PTR(void*, UserHandler);
2288 }
2289
2290 extern "C" {
2291 typedef void (*sa_handler_t)(int);
2292 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *);
2293 }
2294
2295 void* os::signal(int signal_number, void* handler) {
2296 struct sigaction sigAct, oldSigAct;
2297
2298 sigfillset(&(sigAct.sa_mask));
2299 sigAct.sa_flags = SA_RESTART|SA_SIGINFO;
2300 sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler);
2301
2302 if (sigaction(signal_number, &sigAct, &oldSigAct)) {
2303 // -1 means registration failed
2304 return (void *)-1;
2305 }
2306
2307 return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler);
2308 }
2309
2310 void os::signal_raise(int signal_number) {
2311 ::raise(signal_number);
2312 }
2313
2314 /*
2315 * The following code is moved from os.cpp for making this
2316 * code platform specific, which it is by its very nature.
2317 */
2318
2319 // Will be modified when max signal is changed to be dynamic
2320 int os::sigexitnum_pd() {
2321 return NSIG;
2322 }
2323
2324 // a counter for each possible signal value
2325 static volatile jint pending_signals[NSIG+1] = { 0 };
2326
2327 // Linux(POSIX) specific hand shaking semaphore.
2328 static sem_t sig_sem;
2329
2330 void os::signal_init_pd() {
2331 // Initialize signal structures
2332 ::memset((void*)pending_signals, 0, sizeof(pending_signals));
2333
2334 // Initialize signal semaphore
2335 ::sem_init(&sig_sem, 0, 0);
2336 }
2337
2338 void os::signal_notify(int sig) {
2339 Atomic::inc(&pending_signals[sig]);
2340 ::sem_post(&sig_sem);
2341 }
2342
2343 static int check_pending_signals(bool wait) {
2344 Atomic::store(0, &sigint_count);
2345 for (;;) {
2346 for (int i = 0; i < NSIG + 1; i++) {
2347 jint n = pending_signals[i];
2348 if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) {
2349 return i;
2350 }
2351 }
2352 if (!wait) {
2353 return -1;
2354 }
2355 JavaThread *thread = JavaThread::current();
2356 ThreadBlockInVM tbivm(thread);
2357
2358 bool threadIsSuspended;
2359 do {
2360 thread->set_suspend_equivalent();
2361 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
2362 ::sem_wait(&sig_sem);
2363
2364 // were we externally suspended while we were waiting?
2365 threadIsSuspended = thread->handle_special_suspend_equivalent_condition();
2366 if (threadIsSuspended) {
2367 //
2368 // The semaphore has been incremented, but while we were waiting
2369 // another thread suspended us. We don't want to continue running
2370 // while suspended because that would surprise the thread that
2371 // suspended us.
2372 //
2373 ::sem_post(&sig_sem);
2374
2375 thread->java_suspend_self();
2376 }
2377 } while (threadIsSuspended);
2378 }
2379 }
2380
2381 int os::signal_lookup() {
2382 return check_pending_signals(false);
2383 }
2384
2385 int os::signal_wait() {
2386 return check_pending_signals(true);
2387 }
2388
2389 ////////////////////////////////////////////////////////////////////////////////
2390 // Virtual Memory
2391
2392 int os::vm_page_size() {
2393 // Seems redundant as all get out
2394 assert(os::Linux::page_size() != -1, "must call os::init");
2395 return os::Linux::page_size();
2396 }
2397
2398 // Solaris allocates memory by pages.
2399 int os::vm_allocation_granularity() {
2400 assert(os::Linux::page_size() != -1, "must call os::init");
2401 return os::Linux::page_size();
2402 }
2403
2404 // Rationale behind this function:
2405 // current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable
2406 // mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get
2407 // samples for JITted code. Here we create private executable mapping over the code cache
2408 // and then we can use standard (well, almost, as mapping can change) way to provide
2409 // info for the reporting script by storing timestamp and location of symbol
2410 void linux_wrap_code(char* base, size_t size) {
2411 static volatile jint cnt = 0;
2412
2413 if (!UseOprofile) {
2414 return;
2415 }
2416
2417 char buf[PATH_MAX+1];
2418 int num = Atomic::add(1, &cnt);
2419
2420 snprintf(buf, sizeof(buf), "%s/hs-vm-%d-%d",
2421 os::get_temp_directory(), os::current_process_id(), num);
2422 unlink(buf);
2423
2424 int fd = ::open(buf, O_CREAT | O_RDWR, S_IRWXU);
2425
2426 if (fd != -1) {
2427 off_t rv = ::lseek(fd, size-2, SEEK_SET);
2428 if (rv != (off_t)-1) {
2429 if (::write(fd, "", 1) == 1) {
2430 mmap(base, size,
2431 PROT_READ|PROT_WRITE|PROT_EXEC,
2432 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0);
2433 }
2434 }
2435 ::close(fd);
2436 unlink(buf);
2437 }
2438 }
2439
2440 // NOTE: Linux kernel does not really reserve the pages for us.
2441 // All it does is to check if there are enough free pages
2442 // left at the time of mmap(). This could be a potential
2443 // problem.
2444 bool os::pd_commit_memory(char* addr, size_t size, bool exec) {
2445 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
2446 uintptr_t res = (uintptr_t) ::mmap(addr, size, prot,
2447 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0);
2448 if (res != (uintptr_t) MAP_FAILED) {
2449 if (UseNUMAInterleaving) {
2450 numa_make_global(addr, size);
2451 }
2452 return true;
2453 }
2454 return false;
2455 }
2456
2457 // Define MAP_HUGETLB here so we can build HotSpot on old systems.
2458 #ifndef MAP_HUGETLB
2459 #define MAP_HUGETLB 0x40000
2460 #endif
2461
2462 // Define MADV_HUGEPAGE here so we can build HotSpot on old systems.
2463 #ifndef MADV_HUGEPAGE
2464 #define MADV_HUGEPAGE 14
2465 #endif
2466
2467 bool os::pd_commit_memory(char* addr, size_t size, size_t alignment_hint,
2468 bool exec) {
2469 if (UseHugeTLBFS && alignment_hint > (size_t)vm_page_size()) {
2470 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
2471 uintptr_t res =
2472 (uintptr_t) ::mmap(addr, size, prot,
2473 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS|MAP_HUGETLB,
2474 -1, 0);
2475 if (res != (uintptr_t) MAP_FAILED) {
2476 if (UseNUMAInterleaving) {
2477 numa_make_global(addr, size);
2478 }
2479 return true;
2480 }
2481 // Fall through and try to use small pages
2482 }
2483
2484 if (commit_memory(addr, size, exec)) {
2485 realign_memory(addr, size, alignment_hint);
2486 return true;
2487 }
2488 return false;
2489 }
2490
2491 void os::pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint) {
2492 if (UseHugeTLBFS && alignment_hint > (size_t)vm_page_size()) {
2493 // We don't check the return value: madvise(MADV_HUGEPAGE) may not
2494 // be supported or the memory may already be backed by huge pages.
2495 ::madvise(addr, bytes, MADV_HUGEPAGE);
2496 }
2497 }
2498
2499 void os::pd_free_memory(char *addr, size_t bytes, size_t alignment_hint) {
2500 // This method works by doing an mmap over an existing mmaping and effectively discarding
2501 // the existing pages. However it won't work for SHM-based large pages that cannot be
2502 // uncommitted at all. We don't do anything in this case to avoid creating a segment with
2503 // small pages on top of the SHM segment. This method always works for small pages, so we
2504 // allow that in any case.
2505 if (alignment_hint <= (size_t)os::vm_page_size() || !UseSHM) {
2506 commit_memory(addr, bytes, alignment_hint, false);
2507 }
2508 }
2509
2510 void os::numa_make_global(char *addr, size_t bytes) {
2511 Linux::numa_interleave_memory(addr, bytes);
2512 }
2513
2514 void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) {
2515 Linux::numa_tonode_memory(addr, bytes, lgrp_hint);
2516 }
2517
2518 bool os::numa_topology_changed() { return false; }
2519
2520 size_t os::numa_get_groups_num() {
2521 int max_node = Linux::numa_max_node();
2522 return max_node > 0 ? max_node + 1 : 1;
2523 }
2524
2525 int os::numa_get_group_id() {
2526 int cpu_id = Linux::sched_getcpu();
2527 if (cpu_id != -1) {
2528 int lgrp_id = Linux::get_node_by_cpu(cpu_id);
2529 if (lgrp_id != -1) {
2530 return lgrp_id;
2531 }
2532 }
2533 return 0;
2534 }
2535
2536 size_t os::numa_get_leaf_groups(int *ids, size_t size) {
2537 for (size_t i = 0; i < size; i++) {
2538 ids[i] = i;
2539 }
2540 return size;
2541 }
2542
2543 bool os::get_page_info(char *start, page_info* info) {
2544 return false;
2545 }
2546
2547 char *os::scan_pages(char *start, char* end, page_info* page_expected, page_info* page_found) {
2548 return end;
2549 }
2550
2551
2552 int os::Linux::sched_getcpu_syscall(void) {
2553 unsigned int cpu;
2554 int retval = -1;
2555
2556 #if defined(IA32)
2557 # ifndef SYS_getcpu
2558 # define SYS_getcpu 318
2559 # endif
2560 retval = syscall(SYS_getcpu, &cpu, NULL, NULL);
2561 #elif defined(AMD64)
2562 // Unfortunately we have to bring all these macros here from vsyscall.h
2563 // to be able to compile on old linuxes.
2564 # define __NR_vgetcpu 2
2565 # define VSYSCALL_START (-10UL << 20)
2566 # define VSYSCALL_SIZE 1024
2567 # define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr))
2568 typedef long (*vgetcpu_t)(unsigned int *cpu, unsigned int *node, unsigned long *tcache);
2569 vgetcpu_t vgetcpu = (vgetcpu_t)VSYSCALL_ADDR(__NR_vgetcpu);
2570 retval = vgetcpu(&cpu, NULL, NULL);
2571 #endif
2572
2573 return (retval == -1) ? retval : cpu;
2574 }
2575
2576 // Something to do with the numa-aware allocator needs these symbols
2577 extern "C" JNIEXPORT void numa_warn(int number, char *where, ...) { }
2578 extern "C" JNIEXPORT void numa_error(char *where) { }
2579 extern "C" JNIEXPORT int fork1() { return fork(); }
2580
2581
2582 // If we are running with libnuma version > 2, then we should
2583 // be trying to use symbols with versions 1.1
2584 // If we are running with earlier version, which did not have symbol versions,
2585 // we should use the base version.
2586 void* os::Linux::libnuma_dlsym(void* handle, const char *name) {
2587 void *f = dlvsym(handle, name, "libnuma_1.1");
2588 if (f == NULL) {
2589 f = dlsym(handle, name);
2590 }
2591 return f;
2592 }
2593
2594 bool os::Linux::libnuma_init() {
2595 // sched_getcpu() should be in libc.
2596 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t,
2597 dlsym(RTLD_DEFAULT, "sched_getcpu")));
2598
2599 // If it's not, try a direct syscall.
2600 if (sched_getcpu() == -1)
2601 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, (void*)&sched_getcpu_syscall));
2602
2603 if (sched_getcpu() != -1) { // Does it work?
2604 void *handle = dlopen("libnuma.so.1", RTLD_LAZY);
2605 if (handle != NULL) {
2606 set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t,
2607 libnuma_dlsym(handle, "numa_node_to_cpus")));
2608 set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t,
2609 libnuma_dlsym(handle, "numa_max_node")));
2610 set_numa_available(CAST_TO_FN_PTR(numa_available_func_t,
2611 libnuma_dlsym(handle, "numa_available")));
2612 set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t,
2613 libnuma_dlsym(handle, "numa_tonode_memory")));
2614 set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t,
2615 libnuma_dlsym(handle, "numa_interleave_memory")));
2616
2617
2618 if (numa_available() != -1) {
2619 set_numa_all_nodes((unsigned long*)libnuma_dlsym(handle, "numa_all_nodes"));
2620 // Create a cpu -> node mapping
2621 _cpu_to_node = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<int>(0, true);
2622 rebuild_cpu_to_node_map();
2623 return true;
2624 }
2625 }
2626 }
2627 return false;
2628 }
2629
2630 // rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id.
2631 // The table is later used in get_node_by_cpu().
2632 void os::Linux::rebuild_cpu_to_node_map() {
2633 const size_t NCPUS = 32768; // Since the buffer size computation is very obscure
2634 // in libnuma (possible values are starting from 16,
2635 // and continuing up with every other power of 2, but less
2636 // than the maximum number of CPUs supported by kernel), and
2637 // is a subject to change (in libnuma version 2 the requirements
2638 // are more reasonable) we'll just hardcode the number they use
2639 // in the library.
2640 const size_t BitsPerCLong = sizeof(long) * CHAR_BIT;
2641
2642 size_t cpu_num = os::active_processor_count();
2643 size_t cpu_map_size = NCPUS / BitsPerCLong;
2644 size_t cpu_map_valid_size =
2645 MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size);
2646
2647 cpu_to_node()->clear();
2648 cpu_to_node()->at_grow(cpu_num - 1);
2649 size_t node_num = numa_get_groups_num();
2650
2651 unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size, mtInternal);
2652 for (size_t i = 0; i < node_num; i++) {
2653 if (numa_node_to_cpus(i, cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) {
2654 for (size_t j = 0; j < cpu_map_valid_size; j++) {
2655 if (cpu_map[j] != 0) {
2656 for (size_t k = 0; k < BitsPerCLong; k++) {
2657 if (cpu_map[j] & (1UL << k)) {
2658 cpu_to_node()->at_put(j * BitsPerCLong + k, i);
2659 }
2660 }
2661 }
2662 }
2663 }
2664 }
2665 FREE_C_HEAP_ARRAY(unsigned long, cpu_map, mtInternal);
2666 }
2667
2668 int os::Linux::get_node_by_cpu(int cpu_id) {
2669 if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) {
2670 return cpu_to_node()->at(cpu_id);
2671 }
2672 return -1;
2673 }
2674
2675 GrowableArray<int>* os::Linux::_cpu_to_node;
2676 os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu;
2677 os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus;
2678 os::Linux::numa_max_node_func_t os::Linux::_numa_max_node;
2679 os::Linux::numa_available_func_t os::Linux::_numa_available;
2680 os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory;
2681 os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory;
2682 unsigned long* os::Linux::_numa_all_nodes;
2683
2684 bool os::pd_uncommit_memory(char* addr, size_t size) {
2685 uintptr_t res = (uintptr_t) ::mmap(addr, size, PROT_NONE,
2686 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0);
2687 return res != (uintptr_t) MAP_FAILED;
2688 }
2689
2690 // Linux uses a growable mapping for the stack, and if the mapping for
2691 // the stack guard pages is not removed when we detach a thread the
2692 // stack cannot grow beyond the pages where the stack guard was
2693 // mapped. If at some point later in the process the stack expands to
2694 // that point, the Linux kernel cannot expand the stack any further
2695 // because the guard pages are in the way, and a segfault occurs.
2696 //
2697 // However, it's essential not to split the stack region by unmapping
2698 // a region (leaving a hole) that's already part of the stack mapping,
2699 // so if the stack mapping has already grown beyond the guard pages at
2700 // the time we create them, we have to truncate the stack mapping.
2701 // So, we need to know the extent of the stack mapping when
2702 // create_stack_guard_pages() is called.
2703
2704 // Find the bounds of the stack mapping. Return true for success.
2705 //
2706 // We only need this for stacks that are growable: at the time of
2707 // writing thread stacks don't use growable mappings (i.e. those
2708 // creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this
2709 // only applies to the main thread.
2710
2711 static
2712 bool get_stack_bounds(uintptr_t *bottom, uintptr_t *top) {
2713
2714 char buf[128];
2715 int fd, sz;
2716
2717 if ((fd = ::open("/proc/self/maps", O_RDONLY)) < 0) {
2718 return false;
2719 }
2720
2721 const char kw[] = "[stack]";
2722 const int kwlen = sizeof(kw)-1;
2723
2724 // Address part of /proc/self/maps couldn't be more than 128 bytes
2725 while ((sz = os::get_line_chars(fd, buf, sizeof(buf))) > 0) {
2726 if (sz > kwlen && ::memcmp(buf+sz-kwlen, kw, kwlen) == 0) {
2727 // Extract addresses
2728 if (sscanf(buf, "%" SCNxPTR "-%" SCNxPTR, bottom, top) == 2) {
2729 uintptr_t sp = (uintptr_t) __builtin_frame_address(0);
2730 if (sp >= *bottom && sp <= *top) {
2731 ::close(fd);
2732 return true;
2733 }
2734 }
2735 }
2736 }
2737
2738 ::close(fd);
2739 return false;
2740 }
2741
2742
2743 // If the (growable) stack mapping already extends beyond the point
2744 // where we're going to put our guard pages, truncate the mapping at
2745 // that point by munmap()ping it. This ensures that when we later
2746 // munmap() the guard pages we don't leave a hole in the stack
2747 // mapping. This only affects the main/initial thread, but guard
2748 // against future OS changes
2749 bool os::pd_create_stack_guard_pages(char* addr, size_t size) {
2750 uintptr_t stack_extent, stack_base;
2751 bool chk_bounds = NOT_DEBUG(os::Linux::is_initial_thread()) DEBUG_ONLY(true);
2752 if (chk_bounds && get_stack_bounds(&stack_extent, &stack_base)) {
2753 assert(os::Linux::is_initial_thread(),
2754 "growable stack in non-initial thread");
2755 if (stack_extent < (uintptr_t)addr)
2756 ::munmap((void*)stack_extent, (uintptr_t)addr - stack_extent);
2757 }
2758
2759 return os::commit_memory(addr, size);
2760 }
2761
2762 // If this is a growable mapping, remove the guard pages entirely by
2763 // munmap()ping them. If not, just call uncommit_memory(). This only
2764 // affects the main/initial thread, but guard against future OS changes
2765 bool os::remove_stack_guard_pages(char* addr, size_t size) {
2766 uintptr_t stack_extent, stack_base;
2767 bool chk_bounds = NOT_DEBUG(os::Linux::is_initial_thread()) DEBUG_ONLY(true);
2768 if (chk_bounds && get_stack_bounds(&stack_extent, &stack_base)) {
2769 assert(os::Linux::is_initial_thread(),
2770 "growable stack in non-initial thread");
2771
2772 return ::munmap(addr, size) == 0;
2773 }
2774
2775 return os::uncommit_memory(addr, size);
2776 }
2777
2778 static address _highest_vm_reserved_address = NULL;
2779
2780 // If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory
2781 // at 'requested_addr'. If there are existing memory mappings at the same
2782 // location, however, they will be overwritten. If 'fixed' is false,
2783 // 'requested_addr' is only treated as a hint, the return value may or
2784 // may not start from the requested address. Unlike Linux mmap(), this
2785 // function returns NULL to indicate failure.
2786 static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) {
2787 char * addr;
2788 int flags;
2789
2790 flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS;
2791 if (fixed) {
2792 assert((uintptr_t)requested_addr % os::Linux::page_size() == 0, "unaligned address");
2793 flags |= MAP_FIXED;
2794 }
2795
2796 // Map uncommitted pages PROT_READ and PROT_WRITE, change access
2797 // to PROT_EXEC if executable when we commit the page.
2798 addr = (char*)::mmap(requested_addr, bytes, PROT_READ|PROT_WRITE,
2799 flags, -1, 0);
2800
2801 if (addr != MAP_FAILED) {
2802 // anon_mmap() should only get called during VM initialization,
2803 // don't need lock (actually we can skip locking even it can be called
2804 // from multiple threads, because _highest_vm_reserved_address is just a
2805 // hint about the upper limit of non-stack memory regions.)
2806 if ((address)addr + bytes > _highest_vm_reserved_address) {
2807 _highest_vm_reserved_address = (address)addr + bytes;
2808 }
2809 }
2810
2811 return addr == MAP_FAILED ? NULL : addr;
2812 }
2813
2814 // Don't update _highest_vm_reserved_address, because there might be memory
2815 // regions above addr + size. If so, releasing a memory region only creates
2816 // a hole in the address space, it doesn't help prevent heap-stack collision.
2817 //
2818 static int anon_munmap(char * addr, size_t size) {
2819 return ::munmap(addr, size) == 0;
2820 }
2821
2822 char* os::pd_reserve_memory(size_t bytes, char* requested_addr,
2823 size_t alignment_hint) {
2824 return anon_mmap(requested_addr, bytes, (requested_addr != NULL));
2825 }
2826
2827 bool os::pd_release_memory(char* addr, size_t size) {
2828 return anon_munmap(addr, size);
2829 }
2830
2831 static address highest_vm_reserved_address() {
2832 return _highest_vm_reserved_address;
2833 }
2834
2835 static bool linux_mprotect(char* addr, size_t size, int prot) {
2836 // Linux wants the mprotect address argument to be page aligned.
2837 char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::page_size());
2838
2839 // According to SUSv3, mprotect() should only be used with mappings
2840 // established by mmap(), and mmap() always maps whole pages. Unaligned
2841 // 'addr' likely indicates problem in the VM (e.g. trying to change
2842 // protection of malloc'ed or statically allocated memory). Check the
2843 // caller if you hit this assert.
2844 assert(addr == bottom, "sanity check");
2845
2846 size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Linux::page_size());
2847 return ::mprotect(bottom, size, prot) == 0;
2848 }
2849
2850 // Set protections specified
2851 bool os::protect_memory(char* addr, size_t bytes, ProtType prot,
2852 bool is_committed) {
2853 unsigned int p = 0;
2854 switch (prot) {
2855 case MEM_PROT_NONE: p = PROT_NONE; break;
2856 case MEM_PROT_READ: p = PROT_READ; break;
2857 case MEM_PROT_RW: p = PROT_READ|PROT_WRITE; break;
2858 case MEM_PROT_RWX: p = PROT_READ|PROT_WRITE|PROT_EXEC; break;
2859 default:
2860 ShouldNotReachHere();
2861 }
2862 // is_committed is unused.
2863 return linux_mprotect(addr, bytes, p);
2864 }
2865
2866 bool os::guard_memory(char* addr, size_t size) {
2867 return linux_mprotect(addr, size, PROT_NONE);
2868 }
2869
2870 bool os::unguard_memory(char* addr, size_t size) {
2871 return linux_mprotect(addr, size, PROT_READ|PROT_WRITE);
2872 }
2873
2874 bool os::Linux::hugetlbfs_sanity_check(bool warn, size_t page_size) {
2875 bool result = false;
2876 void *p = mmap (NULL, page_size, PROT_READ|PROT_WRITE,
2877 MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB,
2878 -1, 0);
2879
2880 if (p != (void *) -1) {
2881 // We don't know if this really is a huge page or not.
2882 FILE *fp = fopen("/proc/self/maps", "r");
2883 if (fp) {
2884 while (!feof(fp)) {
2885 char chars[257];
2886 long x = 0;
2887 if (fgets(chars, sizeof(chars), fp)) {
2888 if (sscanf(chars, "%lx-%*x", &x) == 1
2889 && x == (long)p) {
2890 if (strstr (chars, "hugepage")) {
2891 result = true;
2892 break;
2893 }
2894 }
2895 }
2896 }
2897 fclose(fp);
2898 }
2899 munmap (p, page_size);
2900 if (result)
2901 return true;
2902 }
2903
2904 if (warn) {
2905 warning("HugeTLBFS is not supported by the operating system.");
2906 }
2907
2908 return result;
2909 }
2910
2911 /*
2912 * Set the coredump_filter bits to include largepages in core dump (bit 6)
2913 *
2914 * From the coredump_filter documentation:
2915 *
2916 * - (bit 0) anonymous private memory
2917 * - (bit 1) anonymous shared memory
2918 * - (bit 2) file-backed private memory
2919 * - (bit 3) file-backed shared memory
2920 * - (bit 4) ELF header pages in file-backed private memory areas (it is
2921 * effective only if the bit 2 is cleared)
2922 * - (bit 5) hugetlb private memory
2923 * - (bit 6) hugetlb shared memory
2924 */
2925 static void set_coredump_filter(void) {
2926 FILE *f;
2927 long cdm;
2928
2929 if ((f = fopen("/proc/self/coredump_filter", "r+")) == NULL) {
2930 return;
2931 }
2932
2933 if (fscanf(f, "%lx", &cdm) != 1) {
2934 fclose(f);
2935 return;
2936 }
2937
2938 rewind(f);
2939
2940 if ((cdm & LARGEPAGES_BIT) == 0) {
2941 cdm |= LARGEPAGES_BIT;
2942 fprintf(f, "%#lx", cdm);
2943 }
2944
2945 fclose(f);
2946 }
2947
2948 // Large page support
2949
2950 static size_t _large_page_size = 0;
2951
2952 void os::large_page_init() {
2953 if (!UseLargePages) {
2954 UseHugeTLBFS = false;
2955 UseSHM = false;
2956 return;
2957 }
2958
2959 if (FLAG_IS_DEFAULT(UseHugeTLBFS) && FLAG_IS_DEFAULT(UseSHM)) {
2960 // If UseLargePages is specified on the command line try both methods,
2961 // if it's default, then try only HugeTLBFS.
2962 if (FLAG_IS_DEFAULT(UseLargePages)) {
2963 UseHugeTLBFS = true;
2964 } else {
2965 UseHugeTLBFS = UseSHM = true;
2966 }
2967 }
2968
2969 if (LargePageSizeInBytes) {
2970 _large_page_size = LargePageSizeInBytes;
2971 } else {
2972 // large_page_size on Linux is used to round up heap size. x86 uses either
2973 // 2M or 4M page, depending on whether PAE (Physical Address Extensions)
2974 // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use
2975 // page as large as 256M.
2976 //
2977 // Here we try to figure out page size by parsing /proc/meminfo and looking
2978 // for a line with the following format:
2979 // Hugepagesize: 2048 kB
2980 //
2981 // If we can't determine the value (e.g. /proc is not mounted, or the text
2982 // format has been changed), we'll use the largest page size supported by
2983 // the processor.
2984
2985 #ifndef ZERO
2986 _large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M)
2987 ARM_ONLY(2 * M) PPC_ONLY(4 * M);
2988 #endif // ZERO
2989
2990 FILE *fp = fopen("/proc/meminfo", "r");
2991 if (fp) {
2992 while (!feof(fp)) {
2993 int x = 0;
2994 char buf[16];
2995 if (fscanf(fp, "Hugepagesize: %d", &x) == 1) {
2996 if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) {
2997 _large_page_size = x * K;
2998 break;
2999 }
3000 } else {
3001 // skip to next line
3002 for (;;) {
3003 int ch = fgetc(fp);
3004 if (ch == EOF || ch == (int)'\n') break;
3005 }
3006 }
3007 }
3008 fclose(fp);
3009 }
3010 }
3011
3012 // print a warning if any large page related flag is specified on command line
3013 bool warn_on_failure = !FLAG_IS_DEFAULT(UseHugeTLBFS);
3014
3015 const size_t default_page_size = (size_t)Linux::page_size();
3016 if (_large_page_size > default_page_size) {
3017 _page_sizes[0] = _large_page_size;
3018 _page_sizes[1] = default_page_size;
3019 _page_sizes[2] = 0;
3020 }
3021 UseHugeTLBFS = UseHugeTLBFS &&
3022 Linux::hugetlbfs_sanity_check(warn_on_failure, _large_page_size);
3023
3024 if (UseHugeTLBFS)
3025 UseSHM = false;
3026
3027 UseLargePages = UseHugeTLBFS || UseSHM;
3028
3029 set_coredump_filter();
3030 }
3031
3032 #ifndef SHM_HUGETLB
3033 #define SHM_HUGETLB 04000
3034 #endif
3035
3036 char* os::reserve_memory_special(size_t bytes, char* req_addr, bool exec) {
3037 // "exec" is passed in but not used. Creating the shared image for
3038 // the code cache doesn't have an SHM_X executable permission to check.
3039 assert(UseLargePages && UseSHM, "only for SHM large pages");
3040
3041 key_t key = IPC_PRIVATE;
3042 char *addr;
3043
3044 bool warn_on_failure = UseLargePages &&
3045 (!FLAG_IS_DEFAULT(UseLargePages) ||
3046 !FLAG_IS_DEFAULT(LargePageSizeInBytes)
3047 );
3048 char msg[128];
3049
3050 // Create a large shared memory region to attach to based on size.
3051 // Currently, size is the total size of the heap
3052 int shmid = shmget(key, bytes, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W);
3053 if (shmid == -1) {
3054 // Possible reasons for shmget failure:
3055 // 1. shmmax is too small for Java heap.
3056 // > check shmmax value: cat /proc/sys/kernel/shmmax
3057 // > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax
3058 // 2. not enough large page memory.
3059 // > check available large pages: cat /proc/meminfo
3060 // > increase amount of large pages:
3061 // echo new_value > /proc/sys/vm/nr_hugepages
3062 // Note 1: different Linux may use different name for this property,
3063 // e.g. on Redhat AS-3 it is "hugetlb_pool".
3064 // Note 2: it's possible there's enough physical memory available but
3065 // they are so fragmented after a long run that they can't
3066 // coalesce into large pages. Try to reserve large pages when
3067 // the system is still "fresh".
3068 if (warn_on_failure) {
3069 jio_snprintf(msg, sizeof(msg), "Failed to reserve shared memory (errno = %d).", errno);
3070 warning(msg);
3071 }
3072 return NULL;
3073 }
3074
3075 // attach to the region
3076 addr = (char*)shmat(shmid, req_addr, 0);
3077 int err = errno;
3078
3079 // Remove shmid. If shmat() is successful, the actual shared memory segment
3080 // will be deleted when it's detached by shmdt() or when the process
3081 // terminates. If shmat() is not successful this will remove the shared
3082 // segment immediately.
3083 shmctl(shmid, IPC_RMID, NULL);
3084
3085 if ((intptr_t)addr == -1) {
3086 if (warn_on_failure) {
3087 jio_snprintf(msg, sizeof(msg), "Failed to attach shared memory (errno = %d).", err);
3088 warning(msg);
3089 }
3090 return NULL;
3091 }
3092
3093 if ((addr != NULL) && UseNUMAInterleaving) {
3094 numa_make_global(addr, bytes);
3095 }
3096
3097 return addr;
3098 }
3099
3100 bool os::release_memory_special(char* base, size_t bytes) {
3101 // detaching the SHM segment will also delete it, see reserve_memory_special()
3102 int rslt = shmdt(base);
3103 return rslt == 0;
3104 }
3105
3106 size_t os::large_page_size() {
3107 return _large_page_size;
3108 }
3109
3110 // HugeTLBFS allows application to commit large page memory on demand;
3111 // with SysV SHM the entire memory region must be allocated as shared
3112 // memory.
3113 bool os::can_commit_large_page_memory() {
3114 return UseHugeTLBFS;
3115 }
3116
3117 bool os::can_execute_large_page_memory() {
3118 return UseHugeTLBFS;
3119 }
3120
3121 // Reserve memory at an arbitrary address, only if that area is
3122 // available (and not reserved for something else).
3123
3124 char* os::pd_attempt_reserve_memory_at(size_t bytes, char* requested_addr) {
3125 const int max_tries = 10;
3126 char* base[max_tries];
3127 size_t size[max_tries];
3128 const size_t gap = 0x000000;
3129
3130 // Assert only that the size is a multiple of the page size, since
3131 // that's all that mmap requires, and since that's all we really know
3132 // about at this low abstraction level. If we need higher alignment,
3133 // we can either pass an alignment to this method or verify alignment
3134 // in one of the methods further up the call chain. See bug 5044738.
3135 assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block");
3136
3137 // Repeatedly allocate blocks until the block is allocated at the
3138 // right spot. Give up after max_tries. Note that reserve_memory() will
3139 // automatically update _highest_vm_reserved_address if the call is
3140 // successful. The variable tracks the highest memory address every reserved
3141 // by JVM. It is used to detect heap-stack collision if running with
3142 // fixed-stack LinuxThreads. Because here we may attempt to reserve more
3143 // space than needed, it could confuse the collision detecting code. To
3144 // solve the problem, save current _highest_vm_reserved_address and
3145 // calculate the correct value before return.
3146 address old_highest = _highest_vm_reserved_address;
3147
3148 // Linux mmap allows caller to pass an address as hint; give it a try first,
3149 // if kernel honors the hint then we can return immediately.
3150 char * addr = anon_mmap(requested_addr, bytes, false);
3151 if (addr == requested_addr) {
3152 return requested_addr;
3153 }
3154
3155 if (addr != NULL) {
3156 // mmap() is successful but it fails to reserve at the requested address
3157 anon_munmap(addr, bytes);
3158 }
3159
3160 int i;
3161 for (i = 0; i < max_tries; ++i) {
3162 base[i] = reserve_memory(bytes);
3163
3164 if (base[i] != NULL) {
3165 // Is this the block we wanted?
3166 if (base[i] == requested_addr) {
3167 size[i] = bytes;
3168 break;
3169 }
3170
3171 // Does this overlap the block we wanted? Give back the overlapped
3172 // parts and try again.
3173
3174 size_t top_overlap = requested_addr + (bytes + gap) - base[i];
3175 if (top_overlap >= 0 && top_overlap < bytes) {
3176 unmap_memory(base[i], top_overlap);
3177 base[i] += top_overlap;
3178 size[i] = bytes - top_overlap;
3179 } else {
3180 size_t bottom_overlap = base[i] + bytes - requested_addr;
3181 if (bottom_overlap >= 0 && bottom_overlap < bytes) {
3182 unmap_memory(requested_addr, bottom_overlap);
3183 size[i] = bytes - bottom_overlap;
3184 } else {
3185 size[i] = bytes;
3186 }
3187 }
3188 }
3189 }
3190
3191 // Give back the unused reserved pieces.
3192
3193 for (int j = 0; j < i; ++j) {
3194 if (base[j] != NULL) {
3195 unmap_memory(base[j], size[j]);
3196 }
3197 }
3198
3199 if (i < max_tries) {
3200 _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes);
3201 return requested_addr;
3202 } else {
3203 _highest_vm_reserved_address = old_highest;
3204 return NULL;
3205 }
3206 }
3207
3208 size_t os::read(int fd, void *buf, unsigned int nBytes) {
3209 return ::read(fd, buf, nBytes);
3210 }
3211
3212 // TODO-FIXME: reconcile Solaris' os::sleep with the linux variation.
3213 // Solaris uses poll(), linux uses park().
3214 // Poll() is likely a better choice, assuming that Thread.interrupt()
3215 // generates a SIGUSRx signal. Note that SIGUSR1 can interfere with
3216 // SIGSEGV, see 4355769.
3217
3218 int os::sleep(Thread* thread, jlong millis, bool interruptible) {
3219 assert(thread == Thread::current(), "thread consistency check");
3220
3221 ParkEvent * const slp = thread->_SleepEvent ;
3222 slp->reset() ;
3223 OrderAccess::fence() ;
3224
3225 if (interruptible) {
3226 jlong prevtime = javaTimeNanos();
3227
3228 for (;;) {
3229 if (os::is_interrupted(thread, true)) {
3230 return OS_INTRPT;
3231 }
3232
3233 jlong newtime = javaTimeNanos();
3234
3235 if (newtime - prevtime < 0) {
3236 // time moving backwards, should only happen if no monotonic clock
3237 // not a guarantee() because JVM should not abort on kernel/glibc bugs
3238 assert(!Linux::supports_monotonic_clock(), "time moving backwards");
3239 } else {
3240 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC;
3241 }
3242
3243 if(millis <= 0) {
3244 return OS_OK;
3245 }
3246
3247 prevtime = newtime;
3248
3249 {
3250 assert(thread->is_Java_thread(), "sanity check");
3251 JavaThread *jt = (JavaThread *) thread;
3252 ThreadBlockInVM tbivm(jt);
3253 OSThreadWaitState osts(jt->osthread(), false /* not Object.wait() */);
3254
3255 jt->set_suspend_equivalent();
3256 // cleared by handle_special_suspend_equivalent_condition() or
3257 // java_suspend_self() via check_and_wait_while_suspended()
3258
3259 slp->park(millis);
3260
3261 // were we externally suspended while we were waiting?
3262 jt->check_and_wait_while_suspended();
3263 }
3264 }
3265 } else {
3266 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */);
3267 jlong prevtime = javaTimeNanos();
3268
3269 for (;;) {
3270 // It'd be nice to avoid the back-to-back javaTimeNanos() calls on
3271 // the 1st iteration ...
3272 jlong newtime = javaTimeNanos();
3273
3274 if (newtime - prevtime < 0) {
3275 // time moving backwards, should only happen if no monotonic clock
3276 // not a guarantee() because JVM should not abort on kernel/glibc bugs
3277 assert(!Linux::supports_monotonic_clock(), "time moving backwards");
3278 } else {
3279 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC;
3280 }
3281
3282 if(millis <= 0) break ;
3283
3284 prevtime = newtime;
3285 slp->park(millis);
3286 }
3287 return OS_OK ;
3288 }
3289 }
3290
3291 int os::naked_sleep() {
3292 // %% make the sleep time an integer flag. for now use 1 millisec.
3293 return os::sleep(Thread::current(), 1, false);
3294 }
3295
3296 // Sleep forever; naked call to OS-specific sleep; use with CAUTION
3297 void os::infinite_sleep() {
3298 while (true) { // sleep forever ...
3299 ::sleep(100); // ... 100 seconds at a time
3300 }
3301 }
3302
3303 // Used to convert frequent JVM_Yield() to nops
3304 bool os::dont_yield() {
3305 return DontYieldALot;
3306 }
3307
3308 void os::yield() {
3309 sched_yield();
3310 }
3311
3312 os::YieldResult os::NakedYield() { sched_yield(); return os::YIELD_UNKNOWN ;}
3313
3314 void os::yield_all(int attempts) {
3315 // Yields to all threads, including threads with lower priorities
3316 // Threads on Linux are all with same priority. The Solaris style
3317 // os::yield_all() with nanosleep(1ms) is not necessary.
3318 sched_yield();
3319 }
3320
3321 // Called from the tight loops to possibly influence time-sharing heuristics
3322 void os::loop_breaker(int attempts) {
3323 os::yield_all(attempts);
3324 }
3325
3326 ////////////////////////////////////////////////////////////////////////////////
3327 // thread priority support
3328
3329 // Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER
3330 // only supports dynamic priority, static priority must be zero. For real-time
3331 // applications, Linux supports SCHED_RR which allows static priority (1-99).
3332 // However, for large multi-threaded applications, SCHED_RR is not only slower
3333 // than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out
3334 // of 5 runs - Sep 2005).
3335 //
3336 // The following code actually changes the niceness of kernel-thread/LWP. It
3337 // has an assumption that setpriority() only modifies one kernel-thread/LWP,
3338 // not the entire user process, and user level threads are 1:1 mapped to kernel
3339 // threads. It has always been the case, but could change in the future. For
3340 // this reason, the code should not be used as default (ThreadPriorityPolicy=0).
3341 // It is only used when ThreadPriorityPolicy=1 and requires root privilege.
3342
3343 int os::java_to_os_priority[CriticalPriority + 1] = {
3344 19, // 0 Entry should never be used
3345
3346 4, // 1 MinPriority
3347 3, // 2
3348 2, // 3
3349
3350 1, // 4
3351 0, // 5 NormPriority
3352 -1, // 6
3353
3354 -2, // 7
3355 -3, // 8
3356 -4, // 9 NearMaxPriority
3357
3358 -5, // 10 MaxPriority
3359
3360 -5 // 11 CriticalPriority
3361 };
3362
3363 static int prio_init() {
3364 if (ThreadPriorityPolicy == 1) {
3365 // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1
3366 // if effective uid is not root. Perhaps, a more elegant way of doing
3367 // this is to test CAP_SYS_NICE capability, but that will require libcap.so
3368 if (geteuid() != 0) {
3369 if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) {
3370 warning("-XX:ThreadPriorityPolicy requires root privilege on Linux");
3371 }
3372 ThreadPriorityPolicy = 0;
3373 }
3374 }
3375 if (UseCriticalJavaThreadPriority) {
3376 os::java_to_os_priority[MaxPriority] = os::java_to_os_priority[CriticalPriority];
3377 }
3378 return 0;
3379 }
3380
3381 OSReturn os::set_native_priority(Thread* thread, int newpri) {
3382 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) return OS_OK;
3383
3384 int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri);
3385 return (ret == 0) ? OS_OK : OS_ERR;
3386 }
3387
3388 OSReturn os::get_native_priority(const Thread* const thread, int *priority_ptr) {
3389 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) {
3390 *priority_ptr = java_to_os_priority[NormPriority];
3391 return OS_OK;
3392 }
3393
3394 errno = 0;
3395 *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id());
3396 return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR);
3397 }
3398
3399 // Hint to the underlying OS that a task switch would not be good.
3400 // Void return because it's a hint and can fail.
3401 void os::hint_no_preempt() {}
3402
3403 ////////////////////////////////////////////////////////////////////////////////
3404 // suspend/resume support
3405
3406 // the low-level signal-based suspend/resume support is a remnant from the
3407 // old VM-suspension that used to be for java-suspension, safepoints etc,
3408 // within hotspot. Now there is a single use-case for this:
3409 // - calling get_thread_pc() on the VMThread by the flat-profiler task
3410 // that runs in the watcher thread.
3411 // The remaining code is greatly simplified from the more general suspension
3412 // code that used to be used.
3413 //
3414 // The protocol is quite simple:
3415 // - suspend:
3416 // - sends a signal to the target thread
3417 // - polls the suspend state of the osthread using a yield loop
3418 // - target thread signal handler (SR_handler) sets suspend state
3419 // and blocks in sigsuspend until continued
3420 // - resume:
3421 // - sets target osthread state to continue
3422 // - sends signal to end the sigsuspend loop in the SR_handler
3423 //
3424 // Note that the SR_lock plays no role in this suspend/resume protocol.
3425 //
3426
3427 static void resume_clear_context(OSThread *osthread) {
3428 osthread->set_ucontext(NULL);
3429 osthread->set_siginfo(NULL);
3430
3431 // notify the suspend action is completed, we have now resumed
3432 osthread->sr.clear_suspended();
3433 }
3434
3435 static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo, ucontext_t* context) {
3436 osthread->set_ucontext(context);
3437 osthread->set_siginfo(siginfo);
3438 }
3439
3440 //
3441 // Handler function invoked when a thread's execution is suspended or
3442 // resumed. We have to be careful that only async-safe functions are
3443 // called here (Note: most pthread functions are not async safe and
3444 // should be avoided.)
3445 //
3446 // Note: sigwait() is a more natural fit than sigsuspend() from an
3447 // interface point of view, but sigwait() prevents the signal hander
3448 // from being run. libpthread would get very confused by not having
3449 // its signal handlers run and prevents sigwait()'s use with the
3450 // mutex granting granting signal.
3451 //
3452 // Currently only ever called on the VMThread
3453 //
3454 static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) {
3455 // Save and restore errno to avoid confusing native code with EINTR
3456 // after sigsuspend.
3457 int old_errno = errno;
3458
3459 Thread* thread = Thread::current();
3460 OSThread* osthread = thread->osthread();
3461 assert(thread->is_VM_thread(), "Must be VMThread");
3462 // read current suspend action
3463 int action = osthread->sr.suspend_action();
3464 if (action == SR_SUSPEND) {
3465 suspend_save_context(osthread, siginfo, context);
3466
3467 // Notify the suspend action is about to be completed. do_suspend()
3468 // waits until SR_SUSPENDED is set and then returns. We will wait
3469 // here for a resume signal and that completes the suspend-other
3470 // action. do_suspend/do_resume is always called as a pair from
3471 // the same thread - so there are no races
3472
3473 // notify the caller
3474 osthread->sr.set_suspended();
3475
3476 sigset_t suspend_set; // signals for sigsuspend()
3477
3478 // get current set of blocked signals and unblock resume signal
3479 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set);
3480 sigdelset(&suspend_set, SR_signum);
3481
3482 // wait here until we are resumed
3483 do {
3484 sigsuspend(&suspend_set);
3485 // ignore all returns until we get a resume signal
3486 } while (osthread->sr.suspend_action() != SR_CONTINUE);
3487
3488 resume_clear_context(osthread);
3489
3490 } else {
3491 assert(action == SR_CONTINUE, "unexpected sr action");
3492 // nothing special to do - just leave the handler
3493 }
3494
3495 errno = old_errno;
3496 }
3497
3498
3499 static int SR_initialize() {
3500 struct sigaction act;
3501 char *s;
3502 /* Get signal number to use for suspend/resume */
3503 if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) {
3504 int sig = ::strtol(s, 0, 10);
3505 if (sig > 0 || sig < _NSIG) {
3506 SR_signum = sig;
3507 }
3508 }
3509
3510 assert(SR_signum > SIGSEGV && SR_signum > SIGBUS,
3511 "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769");
3512
3513 sigemptyset(&SR_sigset);
3514 sigaddset(&SR_sigset, SR_signum);
3515
3516 /* Set up signal handler for suspend/resume */
3517 act.sa_flags = SA_RESTART|SA_SIGINFO;
3518 act.sa_handler = (void (*)(int)) SR_handler;
3519
3520 // SR_signum is blocked by default.
3521 // 4528190 - We also need to block pthread restart signal (32 on all
3522 // supported Linux platforms). Note that LinuxThreads need to block
3523 // this signal for all threads to work properly. So we don't have
3524 // to use hard-coded signal number when setting up the mask.
3525 pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask);
3526
3527 if (sigaction(SR_signum, &act, 0) == -1) {
3528 return -1;
3529 }
3530
3531 // Save signal flag
3532 os::Linux::set_our_sigflags(SR_signum, act.sa_flags);
3533 return 0;
3534 }
3535
3536 static int SR_finalize() {
3537 return 0;
3538 }
3539
3540
3541 // returns true on success and false on error - really an error is fatal
3542 // but this seems the normal response to library errors
3543 static bool do_suspend(OSThread* osthread) {
3544 // mark as suspended and send signal
3545 osthread->sr.set_suspend_action(SR_SUSPEND);
3546 int status = pthread_kill(osthread->pthread_id(), SR_signum);
3547 assert_status(status == 0, status, "pthread_kill");
3548
3549 // check status and wait until notified of suspension
3550 if (status == 0) {
3551 for (int i = 0; !osthread->sr.is_suspended(); i++) {
3552 os::yield_all(i);
3553 }
3554 osthread->sr.set_suspend_action(SR_NONE);
3555 return true;
3556 }
3557 else {
3558 osthread->sr.set_suspend_action(SR_NONE);
3559 return false;
3560 }
3561 }
3562
3563 static void do_resume(OSThread* osthread) {
3564 assert(osthread->sr.is_suspended(), "thread should be suspended");
3565 osthread->sr.set_suspend_action(SR_CONTINUE);
3566
3567 int status = pthread_kill(osthread->pthread_id(), SR_signum);
3568 assert_status(status == 0, status, "pthread_kill");
3569 // check status and wait unit notified of resumption
3570 if (status == 0) {
3571 for (int i = 0; osthread->sr.is_suspended(); i++) {
3572 os::yield_all(i);
3573 }
3574 }
3575 osthread->sr.set_suspend_action(SR_NONE);
3576 }
3577
3578 ////////////////////////////////////////////////////////////////////////////////
3579 // interrupt support
3580
3581 void os::interrupt(Thread* thread) {
3582 assert(Thread::current() == thread || Threads_lock->owned_by_self(),
3583 "possibility of dangling Thread pointer");
3584
3585 OSThread* osthread = thread->osthread();
3586
3587 if (!osthread->interrupted()) {
3588 osthread->set_interrupted(true);
3589 // More than one thread can get here with the same value of osthread,
3590 // resulting in multiple notifications. We do, however, want the store
3591 // to interrupted() to be visible to other threads before we execute unpark().
3592 OrderAccess::fence();
3593 ParkEvent * const slp = thread->_SleepEvent ;
3594 if (slp != NULL) slp->unpark() ;
3595 }
3596
3597 // For JSR166. Unpark even if interrupt status already was set
3598 if (thread->is_Java_thread())
3599 ((JavaThread*)thread)->parker()->unpark();
3600
3601 ParkEvent * ev = thread->_ParkEvent ;
3602 if (ev != NULL) ev->unpark() ;
3603
3604 }
3605
3606 bool os::is_interrupted(Thread* thread, bool clear_interrupted) {
3607 assert(Thread::current() == thread || Threads_lock->owned_by_self(),
3608 "possibility of dangling Thread pointer");
3609
3610 OSThread* osthread = thread->osthread();
3611
3612 bool interrupted = osthread->interrupted();
3613
3614 if (interrupted && clear_interrupted) {
3615 osthread->set_interrupted(false);
3616 // consider thread->_SleepEvent->reset() ... optional optimization
3617 }
3618
3619 return interrupted;
3620 }
3621
3622 ///////////////////////////////////////////////////////////////////////////////////
3623 // signal handling (except suspend/resume)
3624
3625 // This routine may be used by user applications as a "hook" to catch signals.
3626 // The user-defined signal handler must pass unrecognized signals to this
3627 // routine, and if it returns true (non-zero), then the signal handler must
3628 // return immediately. If the flag "abort_if_unrecognized" is true, then this
3629 // routine will never retun false (zero), but instead will execute a VM panic
3630 // routine kill the process.
3631 //
3632 // If this routine returns false, it is OK to call it again. This allows
3633 // the user-defined signal handler to perform checks either before or after
3634 // the VM performs its own checks. Naturally, the user code would be making
3635 // a serious error if it tried to handle an exception (such as a null check
3636 // or breakpoint) that the VM was generating for its own correct operation.
3637 //
3638 // This routine may recognize any of the following kinds of signals:
3639 // SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1.
3640 // It should be consulted by handlers for any of those signals.
3641 //
3642 // The caller of this routine must pass in the three arguments supplied
3643 // to the function referred to in the "sa_sigaction" (not the "sa_handler")
3644 // field of the structure passed to sigaction(). This routine assumes that
3645 // the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART.
3646 //
3647 // Note that the VM will print warnings if it detects conflicting signal
3648 // handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers".
3649 //
3650 extern "C" JNIEXPORT int
3651 JVM_handle_linux_signal(int signo, siginfo_t* siginfo,
3652 void* ucontext, int abort_if_unrecognized);
3653
3654 void signalHandler(int sig, siginfo_t* info, void* uc) {
3655 assert(info != NULL && uc != NULL, "it must be old kernel");
3656 int orig_errno = errno; // Preserve errno value over signal handler.
3657 JVM_handle_linux_signal(sig, info, uc, true);
3658 errno = orig_errno;
3659 }
3660
3661
3662 // This boolean allows users to forward their own non-matching signals
3663 // to JVM_handle_linux_signal, harmlessly.
3664 bool os::Linux::signal_handlers_are_installed = false;
3665
3666 // For signal-chaining
3667 struct sigaction os::Linux::sigact[MAXSIGNUM];
3668 unsigned int os::Linux::sigs = 0;
3669 bool os::Linux::libjsig_is_loaded = false;
3670 typedef struct sigaction *(*get_signal_t)(int);
3671 get_signal_t os::Linux::get_signal_action = NULL;
3672
3673 struct sigaction* os::Linux::get_chained_signal_action(int sig) {
3674 struct sigaction *actp = NULL;
3675
3676 if (libjsig_is_loaded) {
3677 // Retrieve the old signal handler from libjsig
3678 actp = (*get_signal_action)(sig);
3679 }
3680 if (actp == NULL) {
3681 // Retrieve the preinstalled signal handler from jvm
3682 actp = get_preinstalled_handler(sig);
3683 }
3684
3685 return actp;
3686 }
3687
3688 static bool call_chained_handler(struct sigaction *actp, int sig,
3689 siginfo_t *siginfo, void *context) {
3690 // Call the old signal handler
3691 if (actp->sa_handler == SIG_DFL) {
3692 // It's more reasonable to let jvm treat it as an unexpected exception
3693 // instead of taking the default action.
3694 return false;
3695 } else if (actp->sa_handler != SIG_IGN) {
3696 if ((actp->sa_flags & SA_NODEFER) == 0) {
3697 // automaticlly block the signal
3698 sigaddset(&(actp->sa_mask), sig);
3699 }
3700
3701 sa_handler_t hand;
3702 sa_sigaction_t sa;
3703 bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0;
3704 // retrieve the chained handler
3705 if (siginfo_flag_set) {
3706 sa = actp->sa_sigaction;
3707 } else {
3708 hand = actp->sa_handler;
3709 }
3710
3711 if ((actp->sa_flags & SA_RESETHAND) != 0) {
3712 actp->sa_handler = SIG_DFL;
3713 }
3714
3715 // try to honor the signal mask
3716 sigset_t oset;
3717 pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset);
3718
3719 // call into the chained handler
3720 if (siginfo_flag_set) {
3721 (*sa)(sig, siginfo, context);
3722 } else {
3723 (*hand)(sig);
3724 }
3725
3726 // restore the signal mask
3727 pthread_sigmask(SIG_SETMASK, &oset, 0);
3728 }
3729 // Tell jvm's signal handler the signal is taken care of.
3730 return true;
3731 }
3732
3733 bool os::Linux::chained_handler(int sig, siginfo_t* siginfo, void* context) {
3734 bool chained = false;
3735 // signal-chaining
3736 if (UseSignalChaining) {
3737 struct sigaction *actp = get_chained_signal_action(sig);
3738 if (actp != NULL) {
3739 chained = call_chained_handler(actp, sig, siginfo, context);
3740 }
3741 }
3742 return chained;
3743 }
3744
3745 struct sigaction* os::Linux::get_preinstalled_handler(int sig) {
3746 if ((( (unsigned int)1 << sig ) & sigs) != 0) {
3747 return &sigact[sig];
3748 }
3749 return NULL;
3750 }
3751
3752 void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) {
3753 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
3754 sigact[sig] = oldAct;
3755 sigs |= (unsigned int)1 << sig;
3756 }
3757
3758 // for diagnostic
3759 int os::Linux::sigflags[MAXSIGNUM];
3760
3761 int os::Linux::get_our_sigflags(int sig) {
3762 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
3763 return sigflags[sig];
3764 }
3765
3766 void os::Linux::set_our_sigflags(int sig, int flags) {
3767 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
3768 sigflags[sig] = flags;
3769 }
3770
3771 void os::Linux::set_signal_handler(int sig, bool set_installed) {
3772 // Check for overwrite.
3773 struct sigaction oldAct;
3774 sigaction(sig, (struct sigaction*)NULL, &oldAct);
3775
3776 void* oldhand = oldAct.sa_sigaction
3777 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction)
3778 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler);
3779 if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) &&
3780 oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) &&
3781 oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) {
3782 if (AllowUserSignalHandlers || !set_installed) {
3783 // Do not overwrite; user takes responsibility to forward to us.
3784 return;
3785 } else if (UseSignalChaining) {
3786 // save the old handler in jvm
3787 save_preinstalled_handler(sig, oldAct);
3788 // libjsig also interposes the sigaction() call below and saves the
3789 // old sigaction on it own.
3790 } else {
3791 fatal(err_msg("Encountered unexpected pre-existing sigaction handler "
3792 "%#lx for signal %d.", (long)oldhand, sig));
3793 }
3794 }
3795
3796 struct sigaction sigAct;
3797 sigfillset(&(sigAct.sa_mask));
3798 sigAct.sa_handler = SIG_DFL;
3799 if (!set_installed) {
3800 sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
3801 } else {
3802 sigAct.sa_sigaction = signalHandler;
3803 sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
3804 }
3805 // Save flags, which are set by ours
3806 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
3807 sigflags[sig] = sigAct.sa_flags;
3808
3809 int ret = sigaction(sig, &sigAct, &oldAct);
3810 assert(ret == 0, "check");
3811
3812 void* oldhand2 = oldAct.sa_sigaction
3813 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction)
3814 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler);
3815 assert(oldhand2 == oldhand, "no concurrent signal handler installation");
3816 }
3817
3818 // install signal handlers for signals that HotSpot needs to
3819 // handle in order to support Java-level exception handling.
3820
3821 void os::Linux::install_signal_handlers() {
3822 if (!signal_handlers_are_installed) {
3823 signal_handlers_are_installed = true;
3824
3825 // signal-chaining
3826 typedef void (*signal_setting_t)();
3827 signal_setting_t begin_signal_setting = NULL;
3828 signal_setting_t end_signal_setting = NULL;
3829 begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
3830 dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting"));
3831 if (begin_signal_setting != NULL) {
3832 end_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
3833 dlsym(RTLD_DEFAULT, "JVM_end_signal_setting"));
3834 get_signal_action = CAST_TO_FN_PTR(get_signal_t,
3835 dlsym(RTLD_DEFAULT, "JVM_get_signal_action"));
3836 libjsig_is_loaded = true;
3837 assert(UseSignalChaining, "should enable signal-chaining");
3838 }
3839 if (libjsig_is_loaded) {
3840 // Tell libjsig jvm is setting signal handlers
3841 (*begin_signal_setting)();
3842 }
3843
3844 set_signal_handler(SIGSEGV, true);
3845 set_signal_handler(SIGPIPE, true);
3846 set_signal_handler(SIGBUS, true);
3847 set_signal_handler(SIGILL, true);
3848 set_signal_handler(SIGFPE, true);
3849 set_signal_handler(SIGXFSZ, true);
3850
3851 if (libjsig_is_loaded) {
3852 // Tell libjsig jvm finishes setting signal handlers
3853 (*end_signal_setting)();
3854 }
3855
3856 // We don't activate signal checker if libjsig is in place, we trust ourselves
3857 // and if UserSignalHandler is installed all bets are off.
3858 // Log that signal checking is off only if -verbose:jni is specified.
3859 if (CheckJNICalls) {
3860 if (libjsig_is_loaded) {
3861 if (PrintJNIResolving) {
3862 tty->print_cr("Info: libjsig is activated, all active signal checking is disabled");
3863 }
3864 check_signals = false;
3865 }
3866 if (AllowUserSignalHandlers) {
3867 if (PrintJNIResolving) {
3868 tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled");
3869 }
3870 check_signals = false;
3871 }
3872 }
3873 }
3874 }
3875
3876 // This is the fastest way to get thread cpu time on Linux.
3877 // Returns cpu time (user+sys) for any thread, not only for current.
3878 // POSIX compliant clocks are implemented in the kernels 2.6.16+.
3879 // It might work on 2.6.10+ with a special kernel/glibc patch.
3880 // For reference, please, see IEEE Std 1003.1-2004:
3881 // http://www.unix.org/single_unix_specification
3882
3883 jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) {
3884 struct timespec tp;
3885 int rc = os::Linux::clock_gettime(clockid, &tp);
3886 assert(rc == 0, "clock_gettime is expected to return 0 code");
3887
3888 return (tp.tv_sec * NANOSECS_PER_SEC) + tp.tv_nsec;
3889 }
3890
3891 /////
3892 // glibc on Linux platform uses non-documented flag
3893 // to indicate, that some special sort of signal
3894 // trampoline is used.
3895 // We will never set this flag, and we should
3896 // ignore this flag in our diagnostic
3897 #ifdef SIGNIFICANT_SIGNAL_MASK
3898 #undef SIGNIFICANT_SIGNAL_MASK
3899 #endif
3900 #define SIGNIFICANT_SIGNAL_MASK (~0x04000000)
3901
3902 static const char* get_signal_handler_name(address handler,
3903 char* buf, int buflen) {
3904 int offset;
3905 bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset);
3906 if (found) {
3907 // skip directory names
3908 const char *p1, *p2;
3909 p1 = buf;
3910 size_t len = strlen(os::file_separator());
3911 while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len;
3912 jio_snprintf(buf, buflen, "%s+0x%x", p1, offset);
3913 } else {
3914 jio_snprintf(buf, buflen, PTR_FORMAT, handler);
3915 }
3916 return buf;
3917 }
3918
3919 static void print_signal_handler(outputStream* st, int sig,
3920 char* buf, size_t buflen) {
3921 struct sigaction sa;
3922
3923 sigaction(sig, NULL, &sa);
3924
3925 // See comment for SIGNIFICANT_SIGNAL_MASK define
3926 sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
3927
3928 st->print("%s: ", os::exception_name(sig, buf, buflen));
3929
3930 address handler = (sa.sa_flags & SA_SIGINFO)
3931 ? CAST_FROM_FN_PTR(address, sa.sa_sigaction)
3932 : CAST_FROM_FN_PTR(address, sa.sa_handler);
3933
3934 if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) {
3935 st->print("SIG_DFL");
3936 } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) {
3937 st->print("SIG_IGN");
3938 } else {
3939 st->print("[%s]", get_signal_handler_name(handler, buf, buflen));
3940 }
3941
3942 st->print(", sa_mask[0]=" PTR32_FORMAT, *(uint32_t*)&sa.sa_mask);
3943
3944 address rh = VMError::get_resetted_sighandler(sig);
3945 // May be, handler was resetted by VMError?
3946 if(rh != NULL) {
3947 handler = rh;
3948 sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK;
3949 }
3950
3951 st->print(", sa_flags=" PTR32_FORMAT, sa.sa_flags);
3952
3953 // Check: is it our handler?
3954 if(handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) ||
3955 handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) {
3956 // It is our signal handler
3957 // check for flags, reset system-used one!
3958 if((int)sa.sa_flags != os::Linux::get_our_sigflags(sig)) {
3959 st->print(
3960 ", flags was changed from " PTR32_FORMAT ", consider using jsig library",
3961 os::Linux::get_our_sigflags(sig));
3962 }
3963 }
3964 st->cr();
3965 }
3966
3967
3968 #define DO_SIGNAL_CHECK(sig) \
3969 if (!sigismember(&check_signal_done, sig)) \
3970 os::Linux::check_signal_handler(sig)
3971
3972 // This method is a periodic task to check for misbehaving JNI applications
3973 // under CheckJNI, we can add any periodic checks here
3974
3975 void os::run_periodic_checks() {
3976
3977 if (check_signals == false) return;
3978
3979 // SEGV and BUS if overridden could potentially prevent
3980 // generation of hs*.log in the event of a crash, debugging
3981 // such a case can be very challenging, so we absolutely
3982 // check the following for a good measure:
3983 DO_SIGNAL_CHECK(SIGSEGV);
3984 DO_SIGNAL_CHECK(SIGILL);
3985 DO_SIGNAL_CHECK(SIGFPE);
3986 DO_SIGNAL_CHECK(SIGBUS);
3987 DO_SIGNAL_CHECK(SIGPIPE);
3988 DO_SIGNAL_CHECK(SIGXFSZ);
3989
3990
3991 // ReduceSignalUsage allows the user to override these handlers
3992 // see comments at the very top and jvm_solaris.h
3993 if (!ReduceSignalUsage) {
3994 DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL);
3995 DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL);
3996 DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL);
3997 DO_SIGNAL_CHECK(BREAK_SIGNAL);
3998 }
3999
4000 DO_SIGNAL_CHECK(SR_signum);
4001 DO_SIGNAL_CHECK(INTERRUPT_SIGNAL);
4002 }
4003
4004 typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *);
4005
4006 static os_sigaction_t os_sigaction = NULL;
4007
4008 void os::Linux::check_signal_handler(int sig) {
4009 char buf[O_BUFLEN];
4010 address jvmHandler = NULL;
4011
4012
4013 struct sigaction act;
4014 if (os_sigaction == NULL) {
4015 // only trust the default sigaction, in case it has been interposed
4016 os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction");
4017 if (os_sigaction == NULL) return;
4018 }
4019
4020 os_sigaction(sig, (struct sigaction*)NULL, &act);
4021
4022
4023 act.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
4024
4025 address thisHandler = (act.sa_flags & SA_SIGINFO)
4026 ? CAST_FROM_FN_PTR(address, act.sa_sigaction)
4027 : CAST_FROM_FN_PTR(address, act.sa_handler) ;
4028
4029
4030 switch(sig) {
4031 case SIGSEGV:
4032 case SIGBUS:
4033 case SIGFPE:
4034 case SIGPIPE:
4035 case SIGILL:
4036 case SIGXFSZ:
4037 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler);
4038 break;
4039
4040 case SHUTDOWN1_SIGNAL:
4041 case SHUTDOWN2_SIGNAL:
4042 case SHUTDOWN3_SIGNAL:
4043 case BREAK_SIGNAL:
4044 jvmHandler = (address)user_handler();
4045 break;
4046
4047 case INTERRUPT_SIGNAL:
4048 jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL);
4049 break;
4050
4051 default:
4052 if (sig == SR_signum) {
4053 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler);
4054 } else {
4055 return;
4056 }
4057 break;
4058 }
4059
4060 if (thisHandler != jvmHandler) {
4061 tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN));
4062 tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN));
4063 tty->print_cr(" found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN));
4064 // No need to check this sig any longer
4065 sigaddset(&check_signal_done, sig);
4066 } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) {
4067 tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN));
4068 tty->print("expected:" PTR32_FORMAT, os::Linux::get_our_sigflags(sig));
4069 tty->print_cr(" found:" PTR32_FORMAT, act.sa_flags);
4070 // No need to check this sig any longer
4071 sigaddset(&check_signal_done, sig);
4072 }
4073
4074 // Dump all the signal
4075 if (sigismember(&check_signal_done, sig)) {
4076 print_signal_handlers(tty, buf, O_BUFLEN);
4077 }
4078 }
4079
4080 extern void report_error(char* file_name, int line_no, char* title, char* format, ...);
4081
4082 extern bool signal_name(int signo, char* buf, size_t len);
4083
4084 const char* os::exception_name(int exception_code, char* buf, size_t size) {
4085 if (0 < exception_code && exception_code <= SIGRTMAX) {
4086 // signal
4087 if (!signal_name(exception_code, buf, size)) {
4088 jio_snprintf(buf, size, "SIG%d", exception_code);
4089 }
4090 return buf;
4091 } else {
4092 return NULL;
4093 }
4094 }
4095
4096 // this is called _before_ the most of global arguments have been parsed
4097 void os::init(void) {
4098 char dummy; /* used to get a guess on initial stack address */
4099 // first_hrtime = gethrtime();
4100
4101 // With LinuxThreads the JavaMain thread pid (primordial thread)
4102 // is different than the pid of the java launcher thread.
4103 // So, on Linux, the launcher thread pid is passed to the VM
4104 // via the sun.java.launcher.pid property.
4105 // Use this property instead of getpid() if it was correctly passed.
4106 // See bug 6351349.
4107 pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid();
4108
4109 _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid();
4110
4111 clock_tics_per_sec = sysconf(_SC_CLK_TCK);
4112
4113 init_random(1234567);
4114
4115 ThreadCritical::initialize();
4116
4117 Linux::set_page_size(sysconf(_SC_PAGESIZE));
4118 if (Linux::page_size() == -1) {
4119 fatal(err_msg("os_linux.cpp: os::init: sysconf failed (%s)",
4120 strerror(errno)));
4121 }
4122 init_page_sizes((size_t) Linux::page_size());
4123
4124 Linux::initialize_system_info();
4125
4126 // main_thread points to the aboriginal thread
4127 Linux::_main_thread = pthread_self();
4128
4129 Linux::clock_init();
4130 initial_time_count = os::elapsed_counter();
4131 pthread_mutex_init(&dl_mutex, NULL);
4132 }
4133
4134 // To install functions for atexit system call
4135 extern "C" {
4136 static void perfMemory_exit_helper() {
4137 perfMemory_exit();
4138 }
4139 }
4140
4141 // this is called _after_ the global arguments have been parsed
4142 jint os::init_2(void)
4143 {
4144 Linux::fast_thread_clock_init();
4145
4146 // Allocate a single page and mark it as readable for safepoint polling
4147 address polling_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
4148 guarantee( polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page" );
4149
4150 os::set_polling_page( polling_page );
4151
4152 #ifndef PRODUCT
4153 if(Verbose && PrintMiscellaneous)
4154 tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n", (intptr_t)polling_page);
4155 #endif
4156
4157 if (!UseMembar) {
4158 address mem_serialize_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
4159 guarantee( mem_serialize_page != NULL, "mmap Failed for memory serialize page");
4160 os::set_memory_serialize_page( mem_serialize_page );
4161
4162 #ifndef PRODUCT
4163 if(Verbose && PrintMiscellaneous)
4164 tty->print("[Memory Serialize Page address: " INTPTR_FORMAT "]\n", (intptr_t)mem_serialize_page);
4165 #endif
4166 }
4167
4168 os::large_page_init();
4169
4170 // initialize suspend/resume support - must do this before signal_sets_init()
4171 if (SR_initialize() != 0) {
4172 perror("SR_initialize failed");
4173 return JNI_ERR;
4174 }
4175
4176 Linux::signal_sets_init();
4177 Linux::install_signal_handlers();
4178
4179 // Check minimum allowable stack size for thread creation and to initialize
4180 // the java system classes, including StackOverflowError - depends on page
4181 // size. Add a page for compiler2 recursion in main thread.
4182 // Add in 2*BytesPerWord times page size to account for VM stack during
4183 // class initialization depending on 32 or 64 bit VM.
4184 os::Linux::min_stack_allowed = MAX2(os::Linux::min_stack_allowed,
4185 (size_t)(StackYellowPages+StackRedPages+StackShadowPages+
4186 2*BytesPerWord COMPILER2_PRESENT(+1)) * Linux::page_size());
4187
4188 size_t threadStackSizeInBytes = ThreadStackSize * K;
4189 if (threadStackSizeInBytes != 0 &&
4190 threadStackSizeInBytes < os::Linux::min_stack_allowed) {
4191 tty->print_cr("\nThe stack size specified is too small, "
4192 "Specify at least %dk",
4193 os::Linux::min_stack_allowed/ K);
4194 return JNI_ERR;
4195 }
4196
4197 // Make the stack size a multiple of the page size so that
4198 // the yellow/red zones can be guarded.
4199 JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes,
4200 vm_page_size()));
4201
4202 Linux::capture_initial_stack(JavaThread::stack_size_at_create());
4203
4204 Linux::libpthread_init();
4205 if (PrintMiscellaneous && (Verbose || WizardMode)) {
4206 tty->print_cr("[HotSpot is running with %s, %s(%s)]\n",
4207 Linux::glibc_version(), Linux::libpthread_version(),
4208 Linux::is_floating_stack() ? "floating stack" : "fixed stack");
4209 }
4210
4211 if (UseNUMA) {
4212 if (!Linux::libnuma_init()) {
4213 UseNUMA = false;
4214 } else {
4215 if ((Linux::numa_max_node() < 1)) {
4216 // There's only one node(they start from 0), disable NUMA.
4217 UseNUMA = false;
4218 }
4219 }
4220 // With SHM large pages we cannot uncommit a page, so there's not way
4221 // we can make the adaptive lgrp chunk resizing work. If the user specified
4222 // both UseNUMA and UseLargePages (or UseSHM) on the command line - warn and
4223 // disable adaptive resizing.
4224 if (UseNUMA && UseLargePages && UseSHM) {
4225 if (!FLAG_IS_DEFAULT(UseNUMA)) {
4226 if (FLAG_IS_DEFAULT(UseLargePages) && FLAG_IS_DEFAULT(UseSHM)) {
4227 UseLargePages = false;
4228 } else {
4229 warning("UseNUMA is not fully compatible with SHM large pages, disabling adaptive resizing");
4230 UseAdaptiveSizePolicy = false;
4231 UseAdaptiveNUMAChunkSizing = false;
4232 }
4233 } else {
4234 UseNUMA = false;
4235 }
4236 }
4237 if (!UseNUMA && ForceNUMA) {
4238 UseNUMA = true;
4239 }
4240 }
4241
4242 if (MaxFDLimit) {
4243 // set the number of file descriptors to max. print out error
4244 // if getrlimit/setrlimit fails but continue regardless.
4245 struct rlimit nbr_files;
4246 int status = getrlimit(RLIMIT_NOFILE, &nbr_files);
4247 if (status != 0) {
4248 if (PrintMiscellaneous && (Verbose || WizardMode))
4249 perror("os::init_2 getrlimit failed");
4250 } else {
4251 nbr_files.rlim_cur = nbr_files.rlim_max;
4252 status = setrlimit(RLIMIT_NOFILE, &nbr_files);
4253 if (status != 0) {
4254 if (PrintMiscellaneous && (Verbose || WizardMode))
4255 perror("os::init_2 setrlimit failed");
4256 }
4257 }
4258 }
4259
4260 // Initialize lock used to serialize thread creation (see os::create_thread)
4261 Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false));
4262
4263 // at-exit methods are called in the reverse order of their registration.
4264 // atexit functions are called on return from main or as a result of a
4265 // call to exit(3C). There can be only 32 of these functions registered
4266 // and atexit() does not set errno.
4267
4268 if (PerfAllowAtExitRegistration) {
4269 // only register atexit functions if PerfAllowAtExitRegistration is set.
4270 // atexit functions can be delayed until process exit time, which
4271 // can be problematic for embedded VM situations. Embedded VMs should
4272 // call DestroyJavaVM() to assure that VM resources are released.
4273
4274 // note: perfMemory_exit_helper atexit function may be removed in
4275 // the future if the appropriate cleanup code can be added to the
4276 // VM_Exit VMOperation's doit method.
4277 if (atexit(perfMemory_exit_helper) != 0) {
4278 warning("os::init2 atexit(perfMemory_exit_helper) failed");
4279 }
4280 }
4281
4282 // initialize thread priority policy
4283 prio_init();
4284
4285 return JNI_OK;
4286 }
4287
4288 // this is called at the end of vm_initialization
4289 void os::init_3(void)
4290 {
4291 #ifdef JAVASE_EMBEDDED
4292 // Start the MemNotifyThread
4293 if (LowMemoryProtection) {
4294 MemNotifyThread::start();
4295 }
4296 return;
4297 #endif
4298 }
4299
4300 // Mark the polling page as unreadable
4301 void os::make_polling_page_unreadable(void) {
4302 if( !guard_memory((char*)_polling_page, Linux::page_size()) )
4303 fatal("Could not disable polling page");
4304 };
4305
4306 // Mark the polling page as readable
4307 void os::make_polling_page_readable(void) {
4308 if( !linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) {
4309 fatal("Could not enable polling page");
4310 }
4311 };
4312
4313 int os::active_processor_count() {
4314 // Linux doesn't yet have a (official) notion of processor sets,
4315 // so just return the number of online processors.
4316 int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN);
4317 assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check");
4318 return online_cpus;
4319 }
4320
4321 void os::set_native_thread_name(const char *name) {
4322 // Not yet implemented.
4323 return;
4324 }
4325
4326 bool os::distribute_processes(uint length, uint* distribution) {
4327 // Not yet implemented.
4328 return false;
4329 }
4330
4331 bool os::bind_to_processor(uint processor_id) {
4332 // Not yet implemented.
4333 return false;
4334 }
4335
4336 ///
4337
4338 // Suspends the target using the signal mechanism and then grabs the PC before
4339 // resuming the target. Used by the flat-profiler only
4340 ExtendedPC os::get_thread_pc(Thread* thread) {
4341 // Make sure that it is called by the watcher for the VMThread
4342 assert(Thread::current()->is_Watcher_thread(), "Must be watcher");
4343 assert(thread->is_VM_thread(), "Can only be called for VMThread");
4344
4345 ExtendedPC epc;
4346
4347 OSThread* osthread = thread->osthread();
4348 if (do_suspend(osthread)) {
4349 if (osthread->ucontext() != NULL) {
4350 epc = os::Linux::ucontext_get_pc(osthread->ucontext());
4351 } else {
4352 // NULL context is unexpected, double-check this is the VMThread
4353 guarantee(thread->is_VM_thread(), "can only be called for VMThread");
4354 }
4355 do_resume(osthread);
4356 }
4357 // failure means pthread_kill failed for some reason - arguably this is
4358 // a fatal problem, but such problems are ignored elsewhere
4359
4360 return epc;
4361 }
4362
4363 int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond, pthread_mutex_t *_mutex, const struct timespec *_abstime)
4364 {
4365 if (is_NPTL()) {
4366 return pthread_cond_timedwait(_cond, _mutex, _abstime);
4367 } else {
4368 // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control
4369 // word back to default 64bit precision if condvar is signaled. Java
4370 // wants 53bit precision. Save and restore current value.
4371 int fpu = get_fpu_control_word();
4372 int status = pthread_cond_timedwait(_cond, _mutex, _abstime);
4373 set_fpu_control_word(fpu);
4374 return status;
4375 }
4376 }
4377
4378 ////////////////////////////////////////////////////////////////////////////////
4379 // debug support
4380
4381 static address same_page(address x, address y) {
4382 int page_bits = -os::vm_page_size();
4383 if ((intptr_t(x) & page_bits) == (intptr_t(y) & page_bits))
4384 return x;
4385 else if (x > y)
4386 return (address)(intptr_t(y) | ~page_bits) + 1;
4387 else
4388 return (address)(intptr_t(y) & page_bits);
4389 }
4390
4391 bool os::find(address addr, outputStream* st) {
4392 Dl_info dlinfo;
4393 memset(&dlinfo, 0, sizeof(dlinfo));
4394 if (dladdr(addr, &dlinfo)) {
4395 st->print(PTR_FORMAT ": ", addr);
4396 if (dlinfo.dli_sname != NULL) {
4397 st->print("%s+%#x", dlinfo.dli_sname,
4398 addr - (intptr_t)dlinfo.dli_saddr);
4399 } else if (dlinfo.dli_fname) {
4400 st->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase);
4401 } else {
4402 st->print("<absolute address>");
4403 }
4404 if (dlinfo.dli_fname) {
4405 st->print(" in %s", dlinfo.dli_fname);
4406 }
4407 if (dlinfo.dli_fbase) {
4408 st->print(" at " PTR_FORMAT, dlinfo.dli_fbase);
4409 }
4410 st->cr();
4411
4412 if (Verbose) {
4413 // decode some bytes around the PC
4414 address begin = same_page(addr-40, addr);
4415 address end = same_page(addr+40, addr);
4416 address lowest = (address) dlinfo.dli_sname;
4417 if (!lowest) lowest = (address) dlinfo.dli_fbase;
4418 if (begin < lowest) begin = lowest;
4419 Dl_info dlinfo2;
4420 if (dladdr(end, &dlinfo2) && dlinfo2.dli_saddr != dlinfo.dli_saddr
4421 && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin)
4422 end = (address) dlinfo2.dli_saddr;
4423 Disassembler::decode(begin, end, st);
4424 }
4425 return true;
4426 }
4427 return false;
4428 }
4429
4430 ////////////////////////////////////////////////////////////////////////////////
4431 // misc
4432
4433 // This does not do anything on Linux. This is basically a hook for being
4434 // able to use structured exception handling (thread-local exception filters)
4435 // on, e.g., Win32.
4436 void
4437 os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method,
4438 JavaCallArguments* args, Thread* thread) {
4439 f(value, method, args, thread);
4440 }
4441
4442 void os::print_statistics() {
4443 }
4444
4445 int os::message_box(const char* title, const char* message) {
4446 int i;
4447 fdStream err(defaultStream::error_fd());
4448 for (i = 0; i < 78; i++) err.print_raw("=");
4449 err.cr();
4450 err.print_raw_cr(title);
4451 for (i = 0; i < 78; i++) err.print_raw("-");
4452 err.cr();
4453 err.print_raw_cr(message);
4454 for (i = 0; i < 78; i++) err.print_raw("=");
4455 err.cr();
4456
4457 char buf[16];
4458 // Prevent process from exiting upon "read error" without consuming all CPU
4459 while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); }
4460
4461 return buf[0] == 'y' || buf[0] == 'Y';
4462 }
4463
4464 int os::stat(const char *path, struct stat *sbuf) {
4465 char pathbuf[MAX_PATH];
4466 if (strlen(path) > MAX_PATH - 1) {
4467 errno = ENAMETOOLONG;
4468 return -1;
4469 }
4470 os::native_path(strcpy(pathbuf, path));
4471 return ::stat(pathbuf, sbuf);
4472 }
4473
4474 bool os::check_heap(bool force) {
4475 return true;
4476 }
4477
4478 int local_vsnprintf(char* buf, size_t count, const char* format, va_list args) {
4479 return ::vsnprintf(buf, count, format, args);
4480 }
4481
4482 // Is a (classpath) directory empty?
4483 bool os::dir_is_empty(const char* path) {
4484 DIR *dir = NULL;
4485 struct dirent *ptr;
4486
4487 dir = opendir(path);
4488 if (dir == NULL) return true;
4489
4490 /* Scan the directory */
4491 bool result = true;
4492 char buf[sizeof(struct dirent) + MAX_PATH];
4493 while (result && (ptr = ::readdir(dir)) != NULL) {
4494 if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) {
4495 result = false;
4496 }
4497 }
4498 closedir(dir);
4499 return result;
4500 }
4501
4502 // This code originates from JDK's sysOpen and open64_w
4503 // from src/solaris/hpi/src/system_md.c
4504
4505 #ifndef O_DELETE
4506 #define O_DELETE 0x10000
4507 #endif
4508
4509 // Open a file. Unlink the file immediately after open returns
4510 // if the specified oflag has the O_DELETE flag set.
4511 // O_DELETE is used only in j2se/src/share/native/java/util/zip/ZipFile.c
4512
4513 int os::open(const char *path, int oflag, int mode) {
4514
4515 if (strlen(path) > MAX_PATH - 1) {
4516 errno = ENAMETOOLONG;
4517 return -1;
4518 }
4519 int fd;
4520 int o_delete = (oflag & O_DELETE);
4521 oflag = oflag & ~O_DELETE;
4522
4523 fd = ::open64(path, oflag, mode);
4524 if (fd == -1) return -1;
4525
4526 //If the open succeeded, the file might still be a directory
4527 {
4528 struct stat64 buf64;
4529 int ret = ::fstat64(fd, &buf64);
4530 int st_mode = buf64.st_mode;
4531
4532 if (ret != -1) {
4533 if ((st_mode & S_IFMT) == S_IFDIR) {
4534 errno = EISDIR;
4535 ::close(fd);
4536 return -1;
4537 }
4538 } else {
4539 ::close(fd);
4540 return -1;
4541 }
4542 }
4543
4544 /*
4545 * All file descriptors that are opened in the JVM and not
4546 * specifically destined for a subprocess should have the
4547 * close-on-exec flag set. If we don't set it, then careless 3rd
4548 * party native code might fork and exec without closing all
4549 * appropriate file descriptors (e.g. as we do in closeDescriptors in
4550 * UNIXProcess.c), and this in turn might:
4551 *
4552 * - cause end-of-file to fail to be detected on some file
4553 * descriptors, resulting in mysterious hangs, or
4554 *
4555 * - might cause an fopen in the subprocess to fail on a system
4556 * suffering from bug 1085341.
4557 *
4558 * (Yes, the default setting of the close-on-exec flag is a Unix
4559 * design flaw)
4560 *
4561 * See:
4562 * 1085341: 32-bit stdio routines should support file descriptors >255
4563 * 4843136: (process) pipe file descriptor from Runtime.exec not being closed
4564 * 6339493: (process) Runtime.exec does not close all file descriptors on Solaris 9
4565 */
4566 #ifdef FD_CLOEXEC
4567 {
4568 int flags = ::fcntl(fd, F_GETFD);
4569 if (flags != -1)
4570 ::fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
4571 }
4572 #endif
4573
4574 if (o_delete != 0) {
4575 ::unlink(path);
4576 }
4577 return fd;
4578 }
4579
4580
4581 // create binary file, rewriting existing file if required
4582 int os::create_binary_file(const char* path, bool rewrite_existing) {
4583 int oflags = O_WRONLY | O_CREAT;
4584 if (!rewrite_existing) {
4585 oflags |= O_EXCL;
4586 }
4587 return ::open64(path, oflags, S_IREAD | S_IWRITE);
4588 }
4589
4590 // return current position of file pointer
4591 jlong os::current_file_offset(int fd) {
4592 return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR);
4593 }
4594
4595 // move file pointer to the specified offset
4596 jlong os::seek_to_file_offset(int fd, jlong offset) {
4597 return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET);
4598 }
4599
4600 // This code originates from JDK's sysAvailable
4601 // from src/solaris/hpi/src/native_threads/src/sys_api_td.c
4602
4603 int os::available(int fd, jlong *bytes) {
4604 jlong cur, end;
4605 int mode;
4606 struct stat64 buf64;
4607
4608 if (::fstat64(fd, &buf64) >= 0) {
4609 mode = buf64.st_mode;
4610 if (S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) {
4611 /*
4612 * XXX: is the following call interruptible? If so, this might
4613 * need to go through the INTERRUPT_IO() wrapper as for other
4614 * blocking, interruptible calls in this file.
4615 */
4616 int n;
4617 if (::ioctl(fd, FIONREAD, &n) >= 0) {
4618 *bytes = n;
4619 return 1;
4620 }
4621 }
4622 }
4623 if ((cur = ::lseek64(fd, 0L, SEEK_CUR)) == -1) {
4624 return 0;
4625 } else if ((end = ::lseek64(fd, 0L, SEEK_END)) == -1) {
4626 return 0;
4627 } else if (::lseek64(fd, cur, SEEK_SET) == -1) {
4628 return 0;
4629 }
4630 *bytes = end - cur;
4631 return 1;
4632 }
4633
4634 int os::socket_available(int fd, jint *pbytes) {
4635 // Linux doc says EINTR not returned, unlike Solaris
4636 int ret = ::ioctl(fd, FIONREAD, pbytes);
4637
4638 //%% note ioctl can return 0 when successful, JVM_SocketAvailable
4639 // is expected to return 0 on failure and 1 on success to the jdk.
4640 return (ret < 0) ? 0 : 1;
4641 }
4642
4643 // Map a block of memory.
4644 char* os::pd_map_memory(int fd, const char* file_name, size_t file_offset,
4645 char *addr, size_t bytes, bool read_only,
4646 bool allow_exec) {
4647 int prot;
4648 int flags = MAP_PRIVATE;
4649
4650 if (read_only) {
4651 prot = PROT_READ;
4652 } else {
4653 prot = PROT_READ | PROT_WRITE;
4654 }
4655
4656 if (allow_exec) {
4657 prot |= PROT_EXEC;
4658 }
4659
4660 if (addr != NULL) {
4661 flags |= MAP_FIXED;
4662 }
4663
4664 char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags,
4665 fd, file_offset);
4666 if (mapped_address == MAP_FAILED) {
4667 return NULL;
4668 }
4669 return mapped_address;
4670 }
4671
4672
4673 // Remap a block of memory.
4674 char* os::pd_remap_memory(int fd, const char* file_name, size_t file_offset,
4675 char *addr, size_t bytes, bool read_only,
4676 bool allow_exec) {
4677 // same as map_memory() on this OS
4678 return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only,
4679 allow_exec);
4680 }
4681
4682
4683 // Unmap a block of memory.
4684 bool os::pd_unmap_memory(char* addr, size_t bytes) {
4685 return munmap(addr, bytes) == 0;
4686 }
4687
4688 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time);
4689
4690 static clockid_t thread_cpu_clockid(Thread* thread) {
4691 pthread_t tid = thread->osthread()->pthread_id();
4692 clockid_t clockid;
4693
4694 // Get thread clockid
4695 int rc = os::Linux::pthread_getcpuclockid(tid, &clockid);
4696 assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code");
4697 return clockid;
4698 }
4699
4700 // current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool)
4701 // are used by JVM M&M and JVMTI to get user+sys or user CPU time
4702 // of a thread.
4703 //
4704 // current_thread_cpu_time() and thread_cpu_time(Thread*) returns
4705 // the fast estimate available on the platform.
4706
4707 jlong os::current_thread_cpu_time() {
4708 if (os::Linux::supports_fast_thread_cpu_time()) {
4709 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
4710 } else {
4711 // return user + sys since the cost is the same
4712 return slow_thread_cpu_time(Thread::current(), true /* user + sys */);
4713 }
4714 }
4715
4716 jlong os::thread_cpu_time(Thread* thread) {
4717 // consistent with what current_thread_cpu_time() returns
4718 if (os::Linux::supports_fast_thread_cpu_time()) {
4719 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread));
4720 } else {
4721 return slow_thread_cpu_time(thread, true /* user + sys */);
4722 }
4723 }
4724
4725 jlong os::current_thread_cpu_time(bool user_sys_cpu_time) {
4726 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
4727 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
4728 } else {
4729 return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time);
4730 }
4731 }
4732
4733 jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
4734 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
4735 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread));
4736 } else {
4737 return slow_thread_cpu_time(thread, user_sys_cpu_time);
4738 }
4739 }
4740
4741 //
4742 // -1 on error.
4743 //
4744
4745 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
4746 static bool proc_task_unchecked = true;
4747 static const char *proc_stat_path = "/proc/%d/stat";
4748 pid_t tid = thread->osthread()->thread_id();
4749 char *s;
4750 char stat[2048];
4751 int statlen;
4752 char proc_name[64];
4753 int count;
4754 long sys_time, user_time;
4755 char cdummy;
4756 int idummy;
4757 long ldummy;
4758 FILE *fp;
4759
4760 // The /proc/<tid>/stat aggregates per-process usage on
4761 // new Linux kernels 2.6+ where NPTL is supported.
4762 // The /proc/self/task/<tid>/stat still has the per-thread usage.
4763 // See bug 6328462.
4764 // There possibly can be cases where there is no directory
4765 // /proc/self/task, so we check its availability.
4766 if (proc_task_unchecked && os::Linux::is_NPTL()) {
4767 // This is executed only once
4768 proc_task_unchecked = false;
4769 fp = fopen("/proc/self/task", "r");
4770 if (fp != NULL) {
4771 proc_stat_path = "/proc/self/task/%d/stat";
4772 fclose(fp);
4773 }
4774 }
4775
4776 sprintf(proc_name, proc_stat_path, tid);
4777 fp = fopen(proc_name, "r");
4778 if ( fp == NULL ) return -1;
4779 statlen = fread(stat, 1, 2047, fp);
4780 stat[statlen] = '\0';
4781 fclose(fp);
4782
4783 // Skip pid and the command string. Note that we could be dealing with
4784 // weird command names, e.g. user could decide to rename java launcher
4785 // to "java 1.4.2 :)", then the stat file would look like
4786 // 1234 (java 1.4.2 :)) R ... ...
4787 // We don't really need to know the command string, just find the last
4788 // occurrence of ")" and then start parsing from there. See bug 4726580.
4789 s = strrchr(stat, ')');
4790 if (s == NULL ) return -1;
4791
4792 // Skip blank chars
4793 do s++; while (isspace(*s));
4794
4795 count = sscanf(s,"%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu",
4796 &cdummy, &idummy, &idummy, &idummy, &idummy, &idummy,
4797 &ldummy, &ldummy, &ldummy, &ldummy, &ldummy,
4798 &user_time, &sys_time);
4799 if ( count != 13 ) return -1;
4800 if (user_sys_cpu_time) {
4801 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec);
4802 } else {
4803 return (jlong)user_time * (1000000000 / clock_tics_per_sec);
4804 }
4805 }
4806
4807 void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
4808 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits
4809 info_ptr->may_skip_backward = false; // elapsed time not wall time
4810 info_ptr->may_skip_forward = false; // elapsed time not wall time
4811 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned
4812 }
4813
4814 void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
4815 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits
4816 info_ptr->may_skip_backward = false; // elapsed time not wall time
4817 info_ptr->may_skip_forward = false; // elapsed time not wall time
4818 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned
4819 }
4820
4821 bool os::is_thread_cpu_time_supported() {
4822 return true;
4823 }
4824
4825 // System loadavg support. Returns -1 if load average cannot be obtained.
4826 // Linux doesn't yet have a (official) notion of processor sets,
4827 // so just return the system wide load average.
4828 int os::loadavg(double loadavg[], int nelem) {
4829 return ::getloadavg(loadavg, nelem);
4830 }
4831
4832 void os::pause() {
4833 char filename[MAX_PATH];
4834 if (PauseAtStartupFile && PauseAtStartupFile[0]) {
4835 jio_snprintf(filename, MAX_PATH, PauseAtStartupFile);
4836 } else {
4837 jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id());
4838 }
4839
4840 int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
4841 if (fd != -1) {
4842 struct stat buf;
4843 ::close(fd);
4844 while (::stat(filename, &buf) == 0) {
4845 (void)::poll(NULL, 0, 100);
4846 }
4847 } else {
4848 jio_fprintf(stderr,
4849 "Could not open pause file '%s', continuing immediately.\n", filename);
4850 }
4851 }
4852
4853
4854 // Refer to the comments in os_solaris.cpp park-unpark.
4855 //
4856 // Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can
4857 // hang indefinitely. For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable.
4858 // For specifics regarding the bug see GLIBC BUGID 261237 :
4859 // http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html.
4860 // Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future
4861 // will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar
4862 // is used. (The simple C test-case provided in the GLIBC bug report manifests the
4863 // hang). The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos()
4864 // and monitorenter when we're using 1-0 locking. All those operations may result in
4865 // calls to pthread_cond_timedwait(). Using LD_ASSUME_KERNEL to use an older version
4866 // of libpthread avoids the problem, but isn't practical.
4867 //
4868 // Possible remedies:
4869 //
4870 // 1. Establish a minimum relative wait time. 50 to 100 msecs seems to work.
4871 // This is palliative and probabilistic, however. If the thread is preempted
4872 // between the call to compute_abstime() and pthread_cond_timedwait(), more
4873 // than the minimum period may have passed, and the abstime may be stale (in the
4874 // past) resultin in a hang. Using this technique reduces the odds of a hang
4875 // but the JVM is still vulnerable, particularly on heavily loaded systems.
4876 //
4877 // 2. Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead
4878 // of the usual flag-condvar-mutex idiom. The write side of the pipe is set
4879 // NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo)
4880 // reduces to poll()+read(). This works well, but consumes 2 FDs per extant
4881 // thread.
4882 //
4883 // 3. Embargo pthread_cond_timedwait() and implement a native "chron" thread
4884 // that manages timeouts. We'd emulate pthread_cond_timedwait() by enqueuing
4885 // a timeout request to the chron thread and then blocking via pthread_cond_wait().
4886 // This also works well. In fact it avoids kernel-level scalability impediments
4887 // on certain platforms that don't handle lots of active pthread_cond_timedwait()
4888 // timers in a graceful fashion.
4889 //
4890 // 4. When the abstime value is in the past it appears that control returns
4891 // correctly from pthread_cond_timedwait(), but the condvar is left corrupt.
4892 // Subsequent timedwait/wait calls may hang indefinitely. Given that, we
4893 // can avoid the problem by reinitializing the condvar -- by cond_destroy()
4894 // followed by cond_init() -- after all calls to pthread_cond_timedwait().
4895 // It may be possible to avoid reinitialization by checking the return
4896 // value from pthread_cond_timedwait(). In addition to reinitializing the
4897 // condvar we must establish the invariant that cond_signal() is only called
4898 // within critical sections protected by the adjunct mutex. This prevents
4899 // cond_signal() from "seeing" a condvar that's in the midst of being
4900 // reinitialized or that is corrupt. Sadly, this invariant obviates the
4901 // desirable signal-after-unlock optimization that avoids futile context switching.
4902 //
4903 // I'm also concerned that some versions of NTPL might allocate an auxilliary
4904 // structure when a condvar is used or initialized. cond_destroy() would
4905 // release the helper structure. Our reinitialize-after-timedwait fix
4906 // put excessive stress on malloc/free and locks protecting the c-heap.
4907 //
4908 // We currently use (4). See the WorkAroundNTPLTimedWaitHang flag.
4909 // It may be possible to refine (4) by checking the kernel and NTPL verisons
4910 // and only enabling the work-around for vulnerable environments.
4911
4912 // utility to compute the abstime argument to timedwait:
4913 // millis is the relative timeout time
4914 // abstime will be the absolute timeout time
4915 // TODO: replace compute_abstime() with unpackTime()
4916
4917 static struct timespec* compute_abstime(timespec* abstime, jlong millis) {
4918 if (millis < 0) millis = 0;
4919 struct timeval now;
4920 int status = gettimeofday(&now, NULL);
4921 assert(status == 0, "gettimeofday");
4922 jlong seconds = millis / 1000;
4923 millis %= 1000;
4924 if (seconds > 50000000) { // see man cond_timedwait(3T)
4925 seconds = 50000000;
4926 }
4927 abstime->tv_sec = now.tv_sec + seconds;
4928 long usec = now.tv_usec + millis * 1000;
4929 if (usec >= 1000000) {
4930 abstime->tv_sec += 1;
4931 usec -= 1000000;
4932 }
4933 abstime->tv_nsec = usec * 1000;
4934 return abstime;
4935 }
4936
4937
4938 // Test-and-clear _Event, always leaves _Event set to 0, returns immediately.
4939 // Conceptually TryPark() should be equivalent to park(0).
4940
4941 int os::PlatformEvent::TryPark() {
4942 for (;;) {
4943 const int v = _Event ;
4944 guarantee ((v == 0) || (v == 1), "invariant") ;
4945 if (Atomic::cmpxchg (0, &_Event, v) == v) return v ;
4946 }
4947 }
4948
4949 void os::PlatformEvent::park() { // AKA "down()"
4950 // Invariant: Only the thread associated with the Event/PlatformEvent
4951 // may call park().
4952 // TODO: assert that _Assoc != NULL or _Assoc == Self
4953 int v ;
4954 for (;;) {
4955 v = _Event ;
4956 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ;
4957 }
4958 guarantee (v >= 0, "invariant") ;
4959 if (v == 0) {
4960 // Do this the hard way by blocking ...
4961 int status = pthread_mutex_lock(_mutex);
4962 assert_status(status == 0, status, "mutex_lock");
4963 guarantee (_nParked == 0, "invariant") ;
4964 ++ _nParked ;
4965 while (_Event < 0) {
4966 status = pthread_cond_wait(_cond, _mutex);
4967 // for some reason, under 2.7 lwp_cond_wait() may return ETIME ...
4968 // Treat this the same as if the wait was interrupted
4969 if (status == ETIME) { status = EINTR; }
4970 assert_status(status == 0 || status == EINTR, status, "cond_wait");
4971 }
4972 -- _nParked ;
4973
4974 _Event = 0 ;
4975 status = pthread_mutex_unlock(_mutex);
4976 assert_status(status == 0, status, "mutex_unlock");
4977 // Paranoia to ensure our locked and lock-free paths interact
4978 // correctly with each other.
4979 OrderAccess::fence();
4980 }
4981 guarantee (_Event >= 0, "invariant") ;
4982 }
4983
4984 int os::PlatformEvent::park(jlong millis) {
4985 guarantee (_nParked == 0, "invariant") ;
4986
4987 int v ;
4988 for (;;) {
4989 v = _Event ;
4990 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ;
4991 }
4992 guarantee (v >= 0, "invariant") ;
4993 if (v != 0) return OS_OK ;
4994
4995 // We do this the hard way, by blocking the thread.
4996 // Consider enforcing a minimum timeout value.
4997 struct timespec abst;
4998 compute_abstime(&abst, millis);
4999
5000 int ret = OS_TIMEOUT;
5001 int status = pthread_mutex_lock(_mutex);
5002 assert_status(status == 0, status, "mutex_lock");
5003 guarantee (_nParked == 0, "invariant") ;
5004 ++_nParked ;
5005
5006 // Object.wait(timo) will return because of
5007 // (a) notification
5008 // (b) timeout
5009 // (c) thread.interrupt
5010 //
5011 // Thread.interrupt and object.notify{All} both call Event::set.
5012 // That is, we treat thread.interrupt as a special case of notification.
5013 // The underlying Solaris implementation, cond_timedwait, admits
5014 // spurious/premature wakeups, but the JLS/JVM spec prevents the
5015 // JVM from making those visible to Java code. As such, we must
5016 // filter out spurious wakeups. We assume all ETIME returns are valid.
5017 //
5018 // TODO: properly differentiate simultaneous notify+interrupt.
5019 // In that case, we should propagate the notify to another waiter.
5020
5021 while (_Event < 0) {
5022 status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst);
5023 if (status != 0 && WorkAroundNPTLTimedWaitHang) {
5024 pthread_cond_destroy (_cond);
5025 pthread_cond_init (_cond, NULL) ;
5026 }
5027 assert_status(status == 0 || status == EINTR ||
5028 status == ETIME || status == ETIMEDOUT,
5029 status, "cond_timedwait");
5030 if (!FilterSpuriousWakeups) break ; // previous semantics
5031 if (status == ETIME || status == ETIMEDOUT) break ;
5032 // We consume and ignore EINTR and spurious wakeups.
5033 }
5034 --_nParked ;
5035 if (_Event >= 0) {
5036 ret = OS_OK;
5037 }
5038 _Event = 0 ;
5039 status = pthread_mutex_unlock(_mutex);
5040 assert_status(status == 0, status, "mutex_unlock");
5041 assert (_nParked == 0, "invariant") ;
5042 // Paranoia to ensure our locked and lock-free paths interact
5043 // correctly with each other.
5044 OrderAccess::fence();
5045 return ret;
5046 }
5047
5048 void os::PlatformEvent::unpark() {
5049 // Transitions for _Event:
5050 // 0 :=> 1
5051 // 1 :=> 1
5052 // -1 :=> either 0 or 1; must signal target thread
5053 // That is, we can safely transition _Event from -1 to either
5054 // 0 or 1. Forcing 1 is slightly more efficient for back-to-back
5055 // unpark() calls.
5056 // See also: "Semaphores in Plan 9" by Mullender & Cox
5057 //
5058 // Note: Forcing a transition from "-1" to "1" on an unpark() means
5059 // that it will take two back-to-back park() calls for the owning
5060 // thread to block. This has the benefit of forcing a spurious return
5061 // from the first park() call after an unpark() call which will help
5062 // shake out uses of park() and unpark() without condition variables.
5063
5064 if (Atomic::xchg(1, &_Event) >= 0) return;
5065
5066 // Wait for the thread associated with the event to vacate
5067 int status = pthread_mutex_lock(_mutex);
5068 assert_status(status == 0, status, "mutex_lock");
5069 int AnyWaiters = _nParked;
5070 assert(AnyWaiters == 0 || AnyWaiters == 1, "invariant");
5071 if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) {
5072 AnyWaiters = 0;
5073 pthread_cond_signal(_cond);
5074 }
5075 status = pthread_mutex_unlock(_mutex);
5076 assert_status(status == 0, status, "mutex_unlock");
5077 if (AnyWaiters != 0) {
5078 status = pthread_cond_signal(_cond);
5079 assert_status(status == 0, status, "cond_signal");
5080 }
5081
5082 // Note that we signal() _after dropping the lock for "immortal" Events.
5083 // This is safe and avoids a common class of futile wakeups. In rare
5084 // circumstances this can cause a thread to return prematurely from
5085 // cond_{timed}wait() but the spurious wakeup is benign and the victim will
5086 // simply re-test the condition and re-park itself.
5087 }
5088
5089
5090 // JSR166
5091 // -------------------------------------------------------
5092
5093 /*
5094 * The solaris and linux implementations of park/unpark are fairly
5095 * conservative for now, but can be improved. They currently use a
5096 * mutex/condvar pair, plus a a count.
5097 * Park decrements count if > 0, else does a condvar wait. Unpark
5098 * sets count to 1 and signals condvar. Only one thread ever waits
5099 * on the condvar. Contention seen when trying to park implies that someone
5100 * is unparking you, so don't wait. And spurious returns are fine, so there
5101 * is no need to track notifications.
5102 */
5103
5104 #define MAX_SECS 100000000
5105 /*
5106 * This code is common to linux and solaris and will be moved to a
5107 * common place in dolphin.
5108 *
5109 * The passed in time value is either a relative time in nanoseconds
5110 * or an absolute time in milliseconds. Either way it has to be unpacked
5111 * into suitable seconds and nanoseconds components and stored in the
5112 * given timespec structure.
5113 * Given time is a 64-bit value and the time_t used in the timespec is only
5114 * a signed-32-bit value (except on 64-bit Linux) we have to watch for
5115 * overflow if times way in the future are given. Further on Solaris versions
5116 * prior to 10 there is a restriction (see cond_timedwait) that the specified
5117 * number of seconds, in abstime, is less than current_time + 100,000,000.
5118 * As it will be 28 years before "now + 100000000" will overflow we can
5119 * ignore overflow and just impose a hard-limit on seconds using the value
5120 * of "now + 100,000,000". This places a limit on the timeout of about 3.17
5121 * years from "now".
5122 */
5123
5124 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) {
5125 assert (time > 0, "convertTime");
5126
5127 struct timeval now;
5128 int status = gettimeofday(&now, NULL);
5129 assert(status == 0, "gettimeofday");
5130
5131 time_t max_secs = now.tv_sec + MAX_SECS;
5132
5133 if (isAbsolute) {
5134 jlong secs = time / 1000;
5135 if (secs > max_secs) {
5136 absTime->tv_sec = max_secs;
5137 }
5138 else {
5139 absTime->tv_sec = secs;
5140 }
5141 absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC;
5142 }
5143 else {
5144 jlong secs = time / NANOSECS_PER_SEC;
5145 if (secs >= MAX_SECS) {
5146 absTime->tv_sec = max_secs;
5147 absTime->tv_nsec = 0;
5148 }
5149 else {
5150 absTime->tv_sec = now.tv_sec + secs;
5151 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000;
5152 if (absTime->tv_nsec >= NANOSECS_PER_SEC) {
5153 absTime->tv_nsec -= NANOSECS_PER_SEC;
5154 ++absTime->tv_sec; // note: this must be <= max_secs
5155 }
5156 }
5157 }
5158 assert(absTime->tv_sec >= 0, "tv_sec < 0");
5159 assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs");
5160 assert(absTime->tv_nsec >= 0, "tv_nsec < 0");
5161 assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec");
5162 }
5163
5164 void Parker::park(bool isAbsolute, jlong time) {
5165 // Ideally we'd do something useful while spinning, such
5166 // as calling unpackTime().
5167
5168 // Optional fast-path check:
5169 // Return immediately if a permit is available.
5170 // We depend on Atomic::xchg() having full barrier semantics
5171 // since we are doing a lock-free update to _counter.
5172 if (Atomic::xchg(0, &_counter) > 0) return;
5173
5174 Thread* thread = Thread::current();
5175 assert(thread->is_Java_thread(), "Must be JavaThread");
5176 JavaThread *jt = (JavaThread *)thread;
5177
5178 // Optional optimization -- avoid state transitions if there's an interrupt pending.
5179 // Check interrupt before trying to wait
5180 if (Thread::is_interrupted(thread, false)) {
5181 return;
5182 }
5183
5184 // Next, demultiplex/decode time arguments
5185 timespec absTime;
5186 if (time < 0 || (isAbsolute && time == 0) ) { // don't wait at all
5187 return;
5188 }
5189 if (time > 0) {
5190 unpackTime(&absTime, isAbsolute, time);
5191 }
5192
5193
5194 // Enter safepoint region
5195 // Beware of deadlocks such as 6317397.
5196 // The per-thread Parker:: mutex is a classic leaf-lock.
5197 // In particular a thread must never block on the Threads_lock while
5198 // holding the Parker:: mutex. If safepoints are pending both the
5199 // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock.
5200 ThreadBlockInVM tbivm(jt);
5201
5202 // Don't wait if cannot get lock since interference arises from
5203 // unblocking. Also. check interrupt before trying wait
5204 if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) {
5205 return;
5206 }
5207
5208 int status ;
5209 if (_counter > 0) { // no wait needed
5210 _counter = 0;
5211 status = pthread_mutex_unlock(_mutex);
5212 assert (status == 0, "invariant") ;
5213 // Paranoia to ensure our locked and lock-free paths interact
5214 // correctly with each other and Java-level accesses.
5215 OrderAccess::fence();
5216 return;
5217 }
5218
5219 #ifdef ASSERT
5220 // Don't catch signals while blocked; let the running threads have the signals.
5221 // (This allows a debugger to break into the running thread.)
5222 sigset_t oldsigs;
5223 sigset_t* allowdebug_blocked = os::Linux::allowdebug_blocked_signals();
5224 pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs);
5225 #endif
5226
5227 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */);
5228 jt->set_suspend_equivalent();
5229 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
5230
5231 if (time == 0) {
5232 status = pthread_cond_wait (_cond, _mutex) ;
5233 } else {
5234 status = os::Linux::safe_cond_timedwait (_cond, _mutex, &absTime) ;
5235 if (status != 0 && WorkAroundNPTLTimedWaitHang) {
5236 pthread_cond_destroy (_cond) ;
5237 pthread_cond_init (_cond, NULL);
5238 }
5239 }
5240 assert_status(status == 0 || status == EINTR ||
5241 status == ETIME || status == ETIMEDOUT,
5242 status, "cond_timedwait");
5243
5244 #ifdef ASSERT
5245 pthread_sigmask(SIG_SETMASK, &oldsigs, NULL);
5246 #endif
5247
5248 _counter = 0 ;
5249 status = pthread_mutex_unlock(_mutex) ;
5250 assert_status(status == 0, status, "invariant") ;
5251 // Paranoia to ensure our locked and lock-free paths interact
5252 // correctly with each other and Java-level accesses.
5253 OrderAccess::fence();
5254
5255 // If externally suspended while waiting, re-suspend
5256 if (jt->handle_special_suspend_equivalent_condition()) {
5257 jt->java_suspend_self();
5258 }
5259 }
5260
5261 void Parker::unpark() {
5262 int s, status ;
5263 status = pthread_mutex_lock(_mutex);
5264 assert (status == 0, "invariant") ;
5265 s = _counter;
5266 _counter = 1;
5267 if (s < 1) {
5268 if (WorkAroundNPTLTimedWaitHang) {
5269 status = pthread_cond_signal (_cond) ;
5270 assert (status == 0, "invariant") ;
5271 status = pthread_mutex_unlock(_mutex);
5272 assert (status == 0, "invariant") ;
5273 } else {
5274 status = pthread_mutex_unlock(_mutex);
5275 assert (status == 0, "invariant") ;
5276 status = pthread_cond_signal (_cond) ;
5277 assert (status == 0, "invariant") ;
5278 }
5279 } else {
5280 pthread_mutex_unlock(_mutex);
5281 assert (status == 0, "invariant") ;
5282 }
5283 }
5284
5285
5286 extern char** environ;
5287
5288 #ifndef __NR_fork
5289 #define __NR_fork IA32_ONLY(2) IA64_ONLY(not defined) AMD64_ONLY(57)
5290 #endif
5291
5292 #ifndef __NR_execve
5293 #define __NR_execve IA32_ONLY(11) IA64_ONLY(1033) AMD64_ONLY(59)
5294 #endif
5295
5296 // Run the specified command in a separate process. Return its exit value,
5297 // or -1 on failure (e.g. can't fork a new process).
5298 // Unlike system(), this function can be called from signal handler. It
5299 // doesn't block SIGINT et al.
5300 int os::fork_and_exec(char* cmd) {
5301 const char * argv[4] = {"sh", "-c", cmd, NULL};
5302
5303 // fork() in LinuxThreads/NPTL is not async-safe. It needs to run
5304 // pthread_atfork handlers and reset pthread library. All we need is a
5305 // separate process to execve. Make a direct syscall to fork process.
5306 // On IA64 there's no fork syscall, we have to use fork() and hope for
5307 // the best...
5308 pid_t pid = NOT_IA64(syscall(__NR_fork);)
5309 IA64_ONLY(fork();)
5310
5311 if (pid < 0) {
5312 // fork failed
5313 return -1;
5314
5315 } else if (pid == 0) {
5316 // child process
5317
5318 // execve() in LinuxThreads will call pthread_kill_other_threads_np()
5319 // first to kill every thread on the thread list. Because this list is
5320 // not reset by fork() (see notes above), execve() will instead kill
5321 // every thread in the parent process. We know this is the only thread
5322 // in the new process, so make a system call directly.
5323 // IA64 should use normal execve() from glibc to match the glibc fork()
5324 // above.
5325 NOT_IA64(syscall(__NR_execve, "/bin/sh", argv, environ);)
5326 IA64_ONLY(execve("/bin/sh", (char* const*)argv, environ);)
5327
5328 // execve failed
5329 _exit(-1);
5330
5331 } else {
5332 // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't
5333 // care about the actual exit code, for now.
5334
5335 int status;
5336
5337 // Wait for the child process to exit. This returns immediately if
5338 // the child has already exited. */
5339 while (waitpid(pid, &status, 0) < 0) {
5340 switch (errno) {
5341 case ECHILD: return 0;
5342 case EINTR: break;
5343 default: return -1;
5344 }
5345 }
5346
5347 if (WIFEXITED(status)) {
5348 // The child exited normally; get its exit code.
5349 return WEXITSTATUS(status);
5350 } else if (WIFSIGNALED(status)) {
5351 // The child exited because of a signal
5352 // The best value to return is 0x80 + signal number,
5353 // because that is what all Unix shells do, and because
5354 // it allows callers to distinguish between process exit and
5355 // process death by signal.
5356 return 0x80 + WTERMSIG(status);
5357 } else {
5358 // Unknown exit code; pass it through
5359 return status;
5360 }
5361 }
5362 }
5363
5364 // is_headless_jre()
5365 //
5366 // Test for the existence of xawt/libmawt.so or libawt_xawt.so
5367 // in order to report if we are running in a headless jre
5368 //
5369 // Since JDK8 xawt/libmawt.so was moved into the same directory
5370 // as libawt.so, and renamed libawt_xawt.so
5371 //
5372 bool os::is_headless_jre() {
5373 struct stat statbuf;
5374 char buf[MAXPATHLEN];
5375 char libmawtpath[MAXPATHLEN];
5376 const char *xawtstr = "/xawt/libmawt.so";
5377 const char *new_xawtstr = "/libawt_xawt.so";
5378 char *p;
5379
5380 // Get path to libjvm.so
5381 os::jvm_path(buf, sizeof(buf));
5382
5383 // Get rid of libjvm.so
5384 p = strrchr(buf, '/');
5385 if (p == NULL) return false;
5386 else *p = '\0';
5387
5388 // Get rid of client or server
5389 p = strrchr(buf, '/');
5390 if (p == NULL) return false;
5391 else *p = '\0';
5392
5393 // check xawt/libmawt.so
5394 strcpy(libmawtpath, buf);
5395 strcat(libmawtpath, xawtstr);
5396 if (::stat(libmawtpath, &statbuf) == 0) return false;
5397
5398 // check libawt_xawt.so
5399 strcpy(libmawtpath, buf);
5400 strcat(libmawtpath, new_xawtstr);
5401 if (::stat(libmawtpath, &statbuf) == 0) return false;
5402
5403 return true;
5404 }
5405
5406 // Get the default path to the core file
5407 // Returns the length of the string
5408 int os::get_core_path(char* buffer, size_t bufferSize) {
5409 const char* p = get_current_directory(buffer, bufferSize);
5410
5411 if (p == NULL) {
5412 assert(p != NULL, "failed to get current directory");
5413 return 0;
5414 }
5415
5416 return strlen(buffer);
5417 }
5418
5419 #ifdef JAVASE_EMBEDDED
5420 //
5421 // A thread to watch the '/dev/mem_notify' device, which will tell us when the OS is running low on memory.
5422 //
5423 MemNotifyThread* MemNotifyThread::_memnotify_thread = NULL;
5424
5425 // ctor
5426 //
5427 MemNotifyThread::MemNotifyThread(int fd): Thread() {
5428 assert(memnotify_thread() == NULL, "we can only allocate one MemNotifyThread");
5429 _fd = fd;
5430
5431 if (os::create_thread(this, os::os_thread)) {
5432 _memnotify_thread = this;
5433 os::set_priority(this, NearMaxPriority);
5434 os::start_thread(this);
5435 }
5436 }
5437
5438 // Where all the work gets done
5439 //
5440 void MemNotifyThread::run() {
5441 assert(this == memnotify_thread(), "expected the singleton MemNotifyThread");
5442
5443 // Set up the select arguments
5444 fd_set rfds;
5445 if (_fd != -1) {
5446 FD_ZERO(&rfds);
5447 FD_SET(_fd, &rfds);
5448 }
5449
5450 // Now wait for the mem_notify device to wake up
5451 while (1) {
5452 // Wait for the mem_notify device to signal us..
5453 int rc = select(_fd+1, _fd != -1 ? &rfds : NULL, NULL, NULL, NULL);
5454 if (rc == -1) {
5455 perror("select!\n");
5456 break;
5457 } else if (rc) {
5458 //ssize_t free_before = os::available_memory();
5459 //tty->print ("Notified: Free: %dK \n",os::available_memory()/1024);
5460
5461 // The kernel is telling us there is not much memory left...
5462 // try to do something about that
5463
5464 // If we are not already in a GC, try one.
5465 if (!Universe::heap()->is_gc_active()) {
5466 Universe::heap()->collect(GCCause::_allocation_failure);
5467
5468 //ssize_t free_after = os::available_memory();
5469 //tty->print ("Post-Notify: Free: %dK\n",free_after/1024);
5470 //tty->print ("GC freed: %dK\n", (free_after - free_before)/1024);
5471 }
5472 // We might want to do something like the following if we find the GC's are not helping...
5473 // Universe::heap()->size_policy()->set_gc_time_limit_exceeded(true);
5474 }
5475 }
5476 }
5477
5478 //
5479 // See if the /dev/mem_notify device exists, and if so, start a thread to monitor it.
5480 //
5481 void MemNotifyThread::start() {
5482 int fd;
5483 fd = open ("/dev/mem_notify", O_RDONLY, 0);
5484 if (fd < 0) {
5485 return;
5486 }
5487
5488 if (memnotify_thread() == NULL) {
5489 new MemNotifyThread(fd);
5490 }
5491 }
5492 #endif // JAVASE_EMBEDDED