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