1 /*
2 * Copyright (c) 1999, 2014, 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/init.hpp"
48 #include "runtime/java.hpp"
49 #include "runtime/javaCalls.hpp"
50 #include "runtime/mutexLocker.hpp"
51 #include "runtime/objectMonitor.hpp"
52 #include "runtime/osThread.hpp"
53 #include "runtime/perfMemory.hpp"
54 #include "runtime/sharedRuntime.hpp"
55 #include "runtime/statSampler.hpp"
56 #include "runtime/stubRoutines.hpp"
57 #include "runtime/thread.inline.hpp"
58 #include "runtime/threadCritical.hpp"
59 #include "runtime/timer.hpp"
60 #include "services/attachListener.hpp"
61 #include "services/memTracker.hpp"
62 #include "services/runtimeService.hpp"
63 #include "utilities/decoder.hpp"
64 #include "utilities/defaultStream.hpp"
65 #include "utilities/events.hpp"
66 #include "utilities/elfFile.hpp"
67 #include "utilities/growableArray.hpp"
68 #include "utilities/vmError.hpp"
69
70 // put OS-includes here
71 # include <sys/types.h>
72 # include <sys/mman.h>
73 # include <sys/stat.h>
74 # include <sys/select.h>
75 # include <pthread.h>
76 # include <signal.h>
77 # include <errno.h>
78 # include <dlfcn.h>
79 # include <stdio.h>
80 # include <unistd.h>
81 # include <sys/resource.h>
82 # include <pthread.h>
83 # include <sys/stat.h>
84 # include <sys/time.h>
85 # include <sys/times.h>
86 # include <sys/utsname.h>
87 # include <sys/socket.h>
88 # include <sys/wait.h>
89 # include <pwd.h>
90 # include <poll.h>
91 # include <semaphore.h>
92 # include <fcntl.h>
93 # include <string.h>
94 # include <syscall.h>
95 # include <sys/sysinfo.h>
96 # include <gnu/libc-version.h>
97 # include <sys/ipc.h>
98 # include <sys/shm.h>
99 # include <link.h>
100 # include <stdint.h>
101 # include <inttypes.h>
102 # include <sys/ioctl.h>
103
104 // if RUSAGE_THREAD for getrusage() has not been defined, do it here. The code calling
105 // getrusage() is prepared to handle the associated failure.
106 #ifndef RUSAGE_THREAD
107 #define RUSAGE_THREAD (1) /* only the calling thread */
108 #endif
109
110 #define MAX_PATH (2 * K)
111
112 #define MAX_SECS 100000000
113
114 // for timer info max values which include all bits
115 #define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF)
116
117 #define LARGEPAGES_BIT (1 << 6)
118 ////////////////////////////////////////////////////////////////////////////////
119 // global variables
120 julong os::Linux::_physical_memory = 0;
121
122 address os::Linux::_initial_thread_stack_bottom = NULL;
123 uintptr_t os::Linux::_initial_thread_stack_size = 0;
124
125 int (*os::Linux::_clock_gettime)(clockid_t, struct timespec *) = NULL;
126 int (*os::Linux::_pthread_getcpuclockid)(pthread_t, clockid_t *) = NULL;
127 Mutex* os::Linux::_createThread_lock = NULL;
128 pthread_t os::Linux::_main_thread;
129 int os::Linux::_page_size = -1;
130 const int os::Linux::_vm_default_page_size = (8 * K);
131 bool os::Linux::_is_floating_stack = false;
132 bool os::Linux::_is_NPTL = false;
133 bool os::Linux::_supports_fast_thread_cpu_time = false;
134 const char * os::Linux::_glibc_version = NULL;
135 const char * os::Linux::_libpthread_version = NULL;
136 pthread_condattr_t os::Linux::_condattr[1];
137
138 static jlong initial_time_count=0;
139
140 static int clock_tics_per_sec = 100;
141
142 // For diagnostics to print a message once. see run_periodic_checks
143 static sigset_t check_signal_done;
144 static bool check_signals = true;
145
146 static pid_t _initial_pid = 0;
147
148 /* Signal number used to suspend/resume a thread */
149
150 /* do not use any signal number less than SIGSEGV, see 4355769 */
151 static int SR_signum = SIGUSR2;
152 sigset_t SR_sigset;
153
154 /* Used to protect dlsym() calls */
155 static pthread_mutex_t dl_mutex;
156
157 // Declarations
158 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time);
159
160 #ifdef JAVASE_EMBEDDED
161 class MemNotifyThread: public Thread {
162 friend class VMStructs;
163 public:
164 virtual void run();
165
166 private:
167 static MemNotifyThread* _memnotify_thread;
168 int _fd;
169
170 public:
171
172 // Constructor
173 MemNotifyThread(int fd);
174
175 // Tester
176 bool is_memnotify_thread() const { return true; }
177
178 // Printing
179 char* name() const { return (char*)"Linux MemNotify Thread"; }
180
181 // Returns the single instance of the MemNotifyThread
182 static MemNotifyThread* memnotify_thread() { return _memnotify_thread; }
183
184 // Create and start the single instance of MemNotifyThread
185 static void start();
186 };
187 #endif // JAVASE_EMBEDDED
188
189 // utility functions
190
191 static int SR_initialize();
192
193 julong os::available_memory() {
194 return Linux::available_memory();
195 }
196
197 julong os::Linux::available_memory() {
198 // values in struct sysinfo are "unsigned long"
199 struct sysinfo si;
200 sysinfo(&si);
201
202 return (julong)si.freeram * si.mem_unit;
203 }
204
205 julong os::physical_memory() {
206 return Linux::physical_memory();
207 }
208
209 ////////////////////////////////////////////////////////////////////////////////
210 // environment support
211
212 bool os::getenv(const char* name, char* buf, int len) {
213 const char* val = ::getenv(name);
214 if (val != NULL && strlen(val) < (size_t)len) {
215 strcpy(buf, val);
216 return true;
217 }
218 if (len > 0) buf[0] = 0; // return a null string
219 return false;
220 }
221
222
223 // Return true if user is running as root.
224
225 bool os::have_special_privileges() {
226 static bool init = false;
227 static bool privileges = false;
228 if (!init) {
229 privileges = (getuid() != geteuid()) || (getgid() != getegid());
230 init = true;
231 }
232 return privileges;
233 }
234
235
236 #ifndef SYS_gettid
237 // i386: 224, ia64: 1105, amd64: 186, sparc 143
238 #ifdef __ia64__
239 #define SYS_gettid 1105
240 #elif __i386__
241 #define SYS_gettid 224
242 #elif __amd64__
243 #define SYS_gettid 186
244 #elif __sparc__
245 #define SYS_gettid 143
246 #else
247 #error define gettid for the arch
248 #endif
249 #endif
250
251 // Cpu architecture string
252 #if defined(ZERO)
253 static char cpu_arch[] = ZERO_LIBARCH;
254 #elif defined(IA64)
255 static char cpu_arch[] = "ia64";
256 #elif defined(IA32)
257 static char cpu_arch[] = "i386";
258 #elif defined(AMD64)
259 static char cpu_arch[] = "amd64";
260 #elif defined(ARM)
261 static char cpu_arch[] = "arm";
262 #elif defined(PPC32)
263 static char cpu_arch[] = "ppc";
264 #elif defined(PPC64)
265 static char cpu_arch[] = "ppc64";
266 #elif defined(SPARC)
267 # ifdef _LP64
268 static char cpu_arch[] = "sparcv9";
269 # else
270 static char cpu_arch[] = "sparc";
271 # endif
272 #else
273 #error Add appropriate cpu_arch setting
274 #endif
275
276
277 // pid_t gettid()
278 //
279 // Returns the kernel thread id of the currently running thread. Kernel
280 // thread id is used to access /proc.
281 //
282 // (Note that getpid() on LinuxThreads returns kernel thread id too; but
283 // on NPTL, it returns the same pid for all threads, as required by POSIX.)
284 //
285 pid_t os::Linux::gettid() {
286 int rslt = syscall(SYS_gettid);
287 if (rslt == -1) {
288 // old kernel, no NPTL support
289 return getpid();
290 } else {
291 return (pid_t)rslt;
292 }
293 }
294
295 // Most versions of linux have a bug where the number of processors are
296 // determined by looking at the /proc file system. In a chroot environment,
297 // the system call returns 1. This causes the VM to act as if it is
298 // a single processor and elide locking (see is_MP() call).
299 static bool unsafe_chroot_detected = false;
300 static const char *unstable_chroot_error = "/proc file system not found.\n"
301 "Java may be unstable running multithreaded in a chroot "
302 "environment on Linux when /proc filesystem is not mounted.";
303
304 void os::Linux::initialize_system_info() {
305 set_processor_count(sysconf(_SC_NPROCESSORS_CONF));
306 if (processor_count() == 1) {
307 pid_t pid = os::Linux::gettid();
308 char fname[32];
309 jio_snprintf(fname, sizeof(fname), "/proc/%d", pid);
310 FILE *fp = fopen(fname, "r");
311 if (fp == NULL) {
312 unsafe_chroot_detected = true;
313 } else {
314 fclose(fp);
315 }
316 }
317 _physical_memory = (julong)sysconf(_SC_PHYS_PAGES) * (julong)sysconf(_SC_PAGESIZE);
318 assert(processor_count() > 0, "linux error");
319 }
320
321 void os::init_system_properties_values() {
322 // char arch[12];
323 // sysinfo(SI_ARCHITECTURE, arch, sizeof(arch));
324
325 // The next steps are taken in the product version:
326 //
327 // Obtain the JAVA_HOME value from the location of libjvm.so.
328 // This library should be located at:
329 // <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm.so.
330 //
331 // If "/jre/lib/" appears at the right place in the path, then we
332 // assume libjvm.so is installed in a JDK and we use this path.
333 //
334 // Otherwise exit with message: "Could not create the Java virtual machine."
335 //
336 // The following extra steps are taken in the debugging version:
337 //
338 // If "/jre/lib/" does NOT appear at the right place in the path
339 // instead of exit check for $JAVA_HOME environment variable.
340 //
341 // If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>,
342 // then we append a fake suffix "hotspot/libjvm.so" to this path so
343 // it looks like libjvm.so is installed there
344 // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm.so.
345 //
346 // Otherwise exit.
347 //
348 // Important note: if the location of libjvm.so changes this
349 // code needs to be changed accordingly.
350
351 // The next few definitions allow the code to be verbatim:
352 #define malloc(n) (char*)NEW_C_HEAP_ARRAY(char, (n), mtInternal)
353 #define getenv(n) ::getenv(n)
354
355 /*
356 * See ld(1):
357 * The linker uses the following search paths to locate required
358 * shared libraries:
359 * 1: ...
360 * ...
361 * 7: The default directories, normally /lib and /usr/lib.
362 */
363 #if defined(AMD64) || defined(_LP64) && (defined(SPARC) || defined(PPC) || defined(S390))
364 #define DEFAULT_LIBPATH "/usr/lib64:/lib64:/lib:/usr/lib"
365 #else
366 #define DEFAULT_LIBPATH "/lib:/usr/lib"
367 #endif
368
369 #define EXTENSIONS_DIR "/lib/ext"
370 #define ENDORSED_DIR "/lib/endorsed"
371 #define REG_DIR "/usr/java/packages"
372
373 {
374 /* sysclasspath, java_home, dll_dir */
375 {
376 char *home_path;
377 char *dll_path;
378 char *pslash;
379 char buf[MAXPATHLEN];
380 os::jvm_path(buf, sizeof(buf));
381
382 // Found the full path to libjvm.so.
383 // Now cut the path to <java_home>/jre if we can.
384 *(strrchr(buf, '/')) = '\0'; /* get rid of /libjvm.so */
385 pslash = strrchr(buf, '/');
386 if (pslash != NULL)
387 *pslash = '\0'; /* get rid of /{client|server|hotspot} */
388 dll_path = malloc(strlen(buf) + 1);
389 if (dll_path == NULL)
390 return;
391 strcpy(dll_path, buf);
392 Arguments::set_dll_dir(dll_path);
393
394 if (pslash != NULL) {
395 pslash = strrchr(buf, '/');
396 if (pslash != NULL) {
397 *pslash = '\0'; /* get rid of /<arch> */
398 pslash = strrchr(buf, '/');
399 if (pslash != NULL)
400 *pslash = '\0'; /* get rid of /lib */
401 }
402 }
403
404 home_path = malloc(strlen(buf) + 1);
405 if (home_path == NULL)
406 return;
407 strcpy(home_path, buf);
408 Arguments::set_java_home(home_path);
409
410 if (!set_boot_path('/', ':'))
411 return;
412 }
413
414 /*
415 * Where to look for native libraries
416 *
417 * Note: Due to a legacy implementation, most of the library path
418 * is set in the launcher. This was to accomodate linking restrictions
419 * on legacy Linux implementations (which are no longer supported).
420 * Eventually, all the library path setting will be done here.
421 *
422 * However, to prevent the proliferation of improperly built native
423 * libraries, the new path component /usr/java/packages is added here.
424 * Eventually, all the library path setting will be done here.
425 */
426 {
427 char *ld_library_path;
428
429 /*
430 * Construct the invariant part of ld_library_path. Note that the
431 * space for the colon and the trailing null are provided by the
432 * nulls included by the sizeof operator (so actually we allocate
433 * a byte more than necessary).
434 */
435 ld_library_path = (char *) malloc(sizeof(REG_DIR) + sizeof("/lib/") +
436 strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH));
437 sprintf(ld_library_path, REG_DIR "/lib/%s:" DEFAULT_LIBPATH, cpu_arch);
438
439 /*
440 * Get the user setting of LD_LIBRARY_PATH, and prepended it. It
441 * should always exist (until the legacy problem cited above is
442 * addressed).
443 */
444 char *v = getenv("LD_LIBRARY_PATH");
445 if (v != NULL) {
446 char *t = ld_library_path;
447 /* That's +1 for the colon and +1 for the trailing '\0' */
448 ld_library_path = (char *) malloc(strlen(v) + 1 + strlen(t) + 1);
449 sprintf(ld_library_path, "%s:%s", v, t);
450 }
451 Arguments::set_library_path(ld_library_path);
452 }
453
454 /*
455 * Extensions directories.
456 *
457 * Note that the space for the colon and the trailing null are provided
458 * by the nulls included by the sizeof operator (so actually one byte more
459 * than necessary is allocated).
460 */
461 {
462 char *buf = malloc(strlen(Arguments::get_java_home()) +
463 sizeof(EXTENSIONS_DIR) + sizeof(REG_DIR) + sizeof(EXTENSIONS_DIR));
464 sprintf(buf, "%s" EXTENSIONS_DIR ":" REG_DIR EXTENSIONS_DIR,
465 Arguments::get_java_home());
466 Arguments::set_ext_dirs(buf);
467 }
468
469 /* Endorsed standards default directory. */
470 {
471 char * buf;
472 buf = malloc(strlen(Arguments::get_java_home()) + sizeof(ENDORSED_DIR));
473 sprintf(buf, "%s" ENDORSED_DIR, Arguments::get_java_home());
474 Arguments::set_endorsed_dirs(buf);
475 }
476 }
477
478 #undef malloc
479 #undef getenv
480 #undef EXTENSIONS_DIR
481 #undef ENDORSED_DIR
482
483 // Done
484 return;
485 }
486
487 ////////////////////////////////////////////////////////////////////////////////
488 // breakpoint support
489
490 void os::breakpoint() {
491 BREAKPOINT;
492 }
493
494 extern "C" void breakpoint() {
495 // use debugger to set breakpoint here
496 }
497
498 ////////////////////////////////////////////////////////////////////////////////
499 // signal support
500
501 debug_only(static bool signal_sets_initialized = false);
502 static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs;
503
504 bool os::Linux::is_sig_ignored(int sig) {
505 struct sigaction oact;
506 sigaction(sig, (struct sigaction*)NULL, &oact);
507 void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*, oact.sa_sigaction)
508 : CAST_FROM_FN_PTR(void*, oact.sa_handler);
509 if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN))
510 return true;
511 else
512 return false;
513 }
514
515 void os::Linux::signal_sets_init() {
516 // Should also have an assertion stating we are still single-threaded.
517 assert(!signal_sets_initialized, "Already initialized");
518 // Fill in signals that are necessarily unblocked for all threads in
519 // the VM. Currently, we unblock the following signals:
520 // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden
521 // by -Xrs (=ReduceSignalUsage));
522 // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all
523 // other threads. The "ReduceSignalUsage" boolean tells us not to alter
524 // the dispositions or masks wrt these signals.
525 // Programs embedding the VM that want to use the above signals for their
526 // own purposes must, at this time, use the "-Xrs" option to prevent
527 // interference with shutdown hooks and BREAK_SIGNAL thread dumping.
528 // (See bug 4345157, and other related bugs).
529 // In reality, though, unblocking these signals is really a nop, since
530 // these signals are not blocked by default.
531 sigemptyset(&unblocked_sigs);
532 sigemptyset(&allowdebug_blocked_sigs);
533 sigaddset(&unblocked_sigs, SIGILL);
534 sigaddset(&unblocked_sigs, SIGSEGV);
535 sigaddset(&unblocked_sigs, SIGBUS);
536 sigaddset(&unblocked_sigs, SIGFPE);
537 #if defined(PPC64)
538 sigaddset(&unblocked_sigs, SIGTRAP);
539 #endif
540 sigaddset(&unblocked_sigs, SR_signum);
541
542 if (!ReduceSignalUsage) {
543 if (!os::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) {
544 sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL);
545 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL);
546 }
547 if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) {
548 sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL);
549 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL);
550 }
551 if (!os::Linux::is_sig_ignored(SHUTDOWN3_SIGNAL)) {
552 sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL);
553 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN3_SIGNAL);
554 }
555 }
556 // Fill in signals that are blocked by all but the VM thread.
557 sigemptyset(&vm_sigs);
558 if (!ReduceSignalUsage)
559 sigaddset(&vm_sigs, BREAK_SIGNAL);
560 debug_only(signal_sets_initialized = true);
561
562 }
563
564 // These are signals that are unblocked while a thread is running Java.
565 // (For some reason, they get blocked by default.)
566 sigset_t* os::Linux::unblocked_signals() {
567 assert(signal_sets_initialized, "Not initialized");
568 return &unblocked_sigs;
569 }
570
571 // These are the signals that are blocked while a (non-VM) thread is
572 // running Java. Only the VM thread handles these signals.
573 sigset_t* os::Linux::vm_signals() {
574 assert(signal_sets_initialized, "Not initialized");
575 return &vm_sigs;
576 }
577
578 // These are signals that are blocked during cond_wait to allow debugger in
579 sigset_t* os::Linux::allowdebug_blocked_signals() {
580 assert(signal_sets_initialized, "Not initialized");
581 return &allowdebug_blocked_sigs;
582 }
583
584 void os::Linux::hotspot_sigmask(Thread* thread) {
585
586 //Save caller's signal mask before setting VM signal mask
587 sigset_t caller_sigmask;
588 pthread_sigmask(SIG_BLOCK, NULL, &caller_sigmask);
589
590 OSThread* osthread = thread->osthread();
591 osthread->set_caller_sigmask(caller_sigmask);
592
593 pthread_sigmask(SIG_UNBLOCK, os::Linux::unblocked_signals(), NULL);
594
595 if (!ReduceSignalUsage) {
596 if (thread->is_VM_thread()) {
597 // Only the VM thread handles BREAK_SIGNAL ...
598 pthread_sigmask(SIG_UNBLOCK, vm_signals(), NULL);
599 } else {
600 // ... all other threads block BREAK_SIGNAL
601 pthread_sigmask(SIG_BLOCK, vm_signals(), NULL);
602 }
603 }
604 }
605
606 //////////////////////////////////////////////////////////////////////////////
607 // detecting pthread library
608
609 void os::Linux::libpthread_init() {
610 // Save glibc and pthread version strings. Note that _CS_GNU_LIBC_VERSION
611 // and _CS_GNU_LIBPTHREAD_VERSION are supported in glibc >= 2.3.2. Use a
612 // generic name for earlier versions.
613 // Define macros here so we can build HotSpot on old systems.
614 # ifndef _CS_GNU_LIBC_VERSION
615 # define _CS_GNU_LIBC_VERSION 2
616 # endif
617 # ifndef _CS_GNU_LIBPTHREAD_VERSION
618 # define _CS_GNU_LIBPTHREAD_VERSION 3
619 # endif
620
621 size_t n = confstr(_CS_GNU_LIBC_VERSION, NULL, 0);
622 if (n > 0) {
623 char *str = (char *)malloc(n, mtInternal);
624 confstr(_CS_GNU_LIBC_VERSION, str, n);
625 os::Linux::set_glibc_version(str);
626 } else {
627 // _CS_GNU_LIBC_VERSION is not supported, try gnu_get_libc_version()
628 static char _gnu_libc_version[32];
629 jio_snprintf(_gnu_libc_version, sizeof(_gnu_libc_version),
630 "glibc %s %s", gnu_get_libc_version(), gnu_get_libc_release());
631 os::Linux::set_glibc_version(_gnu_libc_version);
632 }
633
634 n = confstr(_CS_GNU_LIBPTHREAD_VERSION, NULL, 0);
635 if (n > 0) {
636 char *str = (char *)malloc(n, mtInternal);
637 confstr(_CS_GNU_LIBPTHREAD_VERSION, str, n);
638 // Vanilla RH-9 (glibc 2.3.2) has a bug that confstr() always tells
639 // us "NPTL-0.29" even we are running with LinuxThreads. Check if this
640 // is the case. LinuxThreads has a hard limit on max number of threads.
641 // So sysconf(_SC_THREAD_THREADS_MAX) will return a positive value.
642 // On the other hand, NPTL does not have such a limit, sysconf()
643 // will return -1 and errno is not changed. Check if it is really NPTL.
644 if (strcmp(os::Linux::glibc_version(), "glibc 2.3.2") == 0 &&
645 strstr(str, "NPTL") &&
646 sysconf(_SC_THREAD_THREADS_MAX) > 0) {
647 free(str);
648 os::Linux::set_libpthread_version("linuxthreads");
649 } else {
650 os::Linux::set_libpthread_version(str);
651 }
652 } else {
653 // glibc before 2.3.2 only has LinuxThreads.
654 os::Linux::set_libpthread_version("linuxthreads");
655 }
656
657 if (strstr(libpthread_version(), "NPTL")) {
658 os::Linux::set_is_NPTL();
659 } else {
660 os::Linux::set_is_LinuxThreads();
661 }
662
663 // LinuxThreads have two flavors: floating-stack mode, which allows variable
664 // stack size; and fixed-stack mode. NPTL is always floating-stack.
665 if (os::Linux::is_NPTL() || os::Linux::supports_variable_stack_size()) {
666 os::Linux::set_is_floating_stack();
667 }
668 }
669
670 /////////////////////////////////////////////////////////////////////////////
671 // thread stack
672
673 // Force Linux kernel to expand current thread stack. If "bottom" is close
674 // to the stack guard, caller should block all signals.
675 //
676 // MAP_GROWSDOWN:
677 // A special mmap() flag that is used to implement thread stacks. It tells
678 // kernel that the memory region should extend downwards when needed. This
679 // allows early versions of LinuxThreads to only mmap the first few pages
680 // when creating a new thread. Linux kernel will automatically expand thread
681 // stack as needed (on page faults).
682 //
683 // However, because the memory region of a MAP_GROWSDOWN stack can grow on
684 // demand, if a page fault happens outside an already mapped MAP_GROWSDOWN
685 // region, it's hard to tell if the fault is due to a legitimate stack
686 // access or because of reading/writing non-exist memory (e.g. buffer
687 // overrun). As a rule, if the fault happens below current stack pointer,
688 // Linux kernel does not expand stack, instead a SIGSEGV is sent to the
689 // application (see Linux kernel fault.c).
690 //
691 // This Linux feature can cause SIGSEGV when VM bangs thread stack for
692 // stack overflow detection.
693 //
694 // Newer version of LinuxThreads (since glibc-2.2, or, RH-7.x) and NPTL do
695 // not use this flag. However, the stack of initial thread is not created
696 // by pthread, it is still MAP_GROWSDOWN. Also it's possible (though
697 // unlikely) that user code can create a thread with MAP_GROWSDOWN stack
698 // and then attach the thread to JVM.
699 //
700 // To get around the problem and allow stack banging on Linux, we need to
701 // manually expand thread stack after receiving the SIGSEGV.
702 //
703 // There are two ways to expand thread stack to address "bottom", we used
704 // both of them in JVM before 1.5:
705 // 1. adjust stack pointer first so that it is below "bottom", and then
706 // touch "bottom"
707 // 2. mmap() the page in question
708 //
709 // Now alternate signal stack is gone, it's harder to use 2. For instance,
710 // if current sp is already near the lower end of page 101, and we need to
711 // call mmap() to map page 100, it is possible that part of the mmap() frame
712 // will be placed in page 100. When page 100 is mapped, it is zero-filled.
713 // That will destroy the mmap() frame and cause VM to crash.
714 //
715 // The following code works by adjusting sp first, then accessing the "bottom"
716 // page to force a page fault. Linux kernel will then automatically expand the
717 // stack mapping.
718 //
719 // _expand_stack_to() assumes its frame size is less than page size, which
720 // should always be true if the function is not inlined.
721
722 #if __GNUC__ < 3 // gcc 2.x does not support noinline attribute
723 #define NOINLINE
724 #else
725 #define NOINLINE __attribute__ ((noinline))
726 #endif
727
728 static void _expand_stack_to(address bottom) NOINLINE;
729
730 static void _expand_stack_to(address bottom) {
731 address sp;
732 size_t size;
733 volatile char *p;
734
735 // Adjust bottom to point to the largest address within the same page, it
736 // gives us a one-page buffer if alloca() allocates slightly more memory.
737 bottom = (address)align_size_down((uintptr_t)bottom, os::Linux::page_size());
738 bottom += os::Linux::page_size() - 1;
739
740 // sp might be slightly above current stack pointer; if that's the case, we
741 // will alloca() a little more space than necessary, which is OK. Don't use
742 // os::current_stack_pointer(), as its result can be slightly below current
743 // stack pointer, causing us to not alloca enough to reach "bottom".
744 sp = (address)&sp;
745
746 if (sp > bottom) {
747 size = sp - bottom;
748 p = (volatile char *)alloca(size);
749 assert(p != NULL && p <= (volatile char *)bottom, "alloca problem?");
750 p[0] = '\0';
751 }
752 }
753
754 bool os::Linux::manually_expand_stack(JavaThread * t, address addr) {
755 assert(t!=NULL, "just checking");
756 assert(t->osthread()->expanding_stack(), "expand should be set");
757 assert(t->stack_base() != NULL, "stack_base was not initialized");
758
759 if (addr < t->stack_base() && addr >= t->stack_yellow_zone_base()) {
760 sigset_t mask_all, old_sigset;
761 sigfillset(&mask_all);
762 pthread_sigmask(SIG_SETMASK, &mask_all, &old_sigset);
763 _expand_stack_to(addr);
764 pthread_sigmask(SIG_SETMASK, &old_sigset, NULL);
765 return true;
766 }
767 return false;
768 }
769
770 //////////////////////////////////////////////////////////////////////////////
771 // create new thread
772
773 static address highest_vm_reserved_address();
774
775 // check if it's safe to start a new thread
776 static bool _thread_safety_check(Thread* thread) {
777 if (os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack()) {
778 // Fixed stack LinuxThreads (SuSE Linux/x86, and some versions of Redhat)
779 // Heap is mmap'ed at lower end of memory space. Thread stacks are
780 // allocated (MAP_FIXED) from high address space. Every thread stack
781 // occupies a fixed size slot (usually 2Mbytes, but user can change
782 // it to other values if they rebuild LinuxThreads).
783 //
784 // Problem with MAP_FIXED is that mmap() can still succeed even part of
785 // the memory region has already been mmap'ed. That means if we have too
786 // many threads and/or very large heap, eventually thread stack will
787 // collide with heap.
788 //
789 // Here we try to prevent heap/stack collision by comparing current
790 // stack bottom with the highest address that has been mmap'ed by JVM
791 // plus a safety margin for memory maps created by native code.
792 //
793 // This feature can be disabled by setting ThreadSafetyMargin to 0
794 //
795 if (ThreadSafetyMargin > 0) {
796 address stack_bottom = os::current_stack_base() - os::current_stack_size();
797
798 // not safe if our stack extends below the safety margin
799 return stack_bottom - ThreadSafetyMargin >= highest_vm_reserved_address();
800 } else {
801 return true;
802 }
803 } else {
804 // Floating stack LinuxThreads or NPTL:
805 // Unlike fixed stack LinuxThreads, thread stacks are not MAP_FIXED. When
806 // there's not enough space left, pthread_create() will fail. If we come
807 // here, that means enough space has been reserved for stack.
808 return true;
809 }
810 }
811
812 // Thread start routine for all newly created threads
813 static void *java_start(Thread *thread) {
814 // Try to randomize the cache line index of hot stack frames.
815 // This helps when threads of the same stack traces evict each other's
816 // cache lines. The threads can be either from the same JVM instance, or
817 // from different JVM instances. The benefit is especially true for
818 // processors with hyperthreading technology.
819 static int counter = 0;
820 int pid = os::current_process_id();
821 alloca(((pid ^ counter++) & 7) * 128);
822
823 ThreadLocalStorage::set_thread(thread);
824
825 OSThread* osthread = thread->osthread();
826 Monitor* sync = osthread->startThread_lock();
827
828 // non floating stack LinuxThreads needs extra check, see above
829 if (!_thread_safety_check(thread)) {
830 // notify parent thread
831 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
832 osthread->set_state(ZOMBIE);
833 sync->notify_all();
834 return NULL;
835 }
836
837 // thread_id is kernel thread id (similar to Solaris LWP id)
838 osthread->set_thread_id(os::Linux::gettid());
839
840 if (UseNUMA) {
841 int lgrp_id = os::numa_get_group_id();
842 if (lgrp_id != -1) {
843 thread->set_lgrp_id(lgrp_id);
844 }
845 }
846 // initialize signal mask for this thread
847 os::Linux::hotspot_sigmask(thread);
848
849 // initialize floating point control register
850 os::Linux::init_thread_fpu_state();
851
852 // handshaking with parent thread
853 {
854 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
855
856 // notify parent thread
857 osthread->set_state(INITIALIZED);
858 sync->notify_all();
859
860 // wait until os::start_thread()
861 while (osthread->get_state() == INITIALIZED) {
862 sync->wait(Mutex::_no_safepoint_check_flag);
863 }
864 }
865
866 // call one more level start routine
867 thread->run();
868
869 return 0;
870 }
871
872 bool os::create_thread(Thread* thread, ThreadType thr_type, size_t stack_size) {
873 assert(thread->osthread() == NULL, "caller responsible");
874
875 // Allocate the OSThread object
876 OSThread* osthread = new OSThread(NULL, NULL);
877 if (osthread == NULL) {
878 return false;
879 }
880
881 // set the correct thread state
882 osthread->set_thread_type(thr_type);
883
884 // Initial state is ALLOCATED but not INITIALIZED
885 osthread->set_state(ALLOCATED);
886
887 thread->set_osthread(osthread);
888
889 // init thread attributes
890 pthread_attr_t attr;
891 pthread_attr_init(&attr);
892 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
893
894 // stack size
895 if (os::Linux::supports_variable_stack_size()) {
896 // calculate stack size if it's not specified by caller
897 if (stack_size == 0) {
898 stack_size = os::Linux::default_stack_size(thr_type);
899
900 switch (thr_type) {
901 case os::java_thread:
902 // Java threads use ThreadStackSize which default value can be
903 // changed with the flag -Xss
904 assert (JavaThread::stack_size_at_create() > 0, "this should be set");
905 stack_size = JavaThread::stack_size_at_create();
906 break;
907 case os::compiler_thread:
908 if (CompilerThreadStackSize > 0) {
909 stack_size = (size_t)(CompilerThreadStackSize * K);
910 break;
911 } // else fall through:
912 // use VMThreadStackSize if CompilerThreadStackSize is not defined
913 case os::vm_thread:
914 case os::pgc_thread:
915 case os::cgc_thread:
916 case os::watcher_thread:
917 if (VMThreadStackSize > 0) stack_size = (size_t)(VMThreadStackSize * K);
918 break;
919 }
920 }
921
922 stack_size = MAX2(stack_size, os::Linux::min_stack_allowed);
923 pthread_attr_setstacksize(&attr, stack_size);
924 } else {
925 // let pthread_create() pick the default value.
926 }
927
928 // glibc guard page
929 pthread_attr_setguardsize(&attr, os::Linux::default_guard_size(thr_type));
930
931 ThreadState state;
932
933 {
934 // Serialize thread creation if we are running with fixed stack LinuxThreads
935 bool lock = os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack();
936 if (lock) {
937 os::Linux::createThread_lock()->lock_without_safepoint_check();
938 }
939
940 pthread_t tid;
941 int ret = pthread_create(&tid, &attr, (void* (*)(void*)) java_start, thread);
942
943 pthread_attr_destroy(&attr);
944
945 if (ret != 0) {
946 if (PrintMiscellaneous && (Verbose || WizardMode)) {
947 perror("pthread_create()");
948 }
949 // Need to clean up stuff we've allocated so far
950 thread->set_osthread(NULL);
951 delete osthread;
952 if (lock) os::Linux::createThread_lock()->unlock();
953 return false;
954 }
955
956 // Store pthread info into the OSThread
957 osthread->set_pthread_id(tid);
958
959 // Wait until child thread is either initialized or aborted
960 {
961 Monitor* sync_with_child = osthread->startThread_lock();
962 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
963 while ((state = osthread->get_state()) == ALLOCATED) {
964 sync_with_child->wait(Mutex::_no_safepoint_check_flag);
965 }
966 }
967
968 if (lock) {
969 os::Linux::createThread_lock()->unlock();
970 }
971 }
972
973 // Aborted due to thread limit being reached
974 if (state == ZOMBIE) {
975 thread->set_osthread(NULL);
976 delete osthread;
977 return false;
978 }
979
980 // The thread is returned suspended (in state INITIALIZED),
981 // and is started higher up in the call chain
982 assert(state == INITIALIZED, "race condition");
983 return true;
984 }
985
986 /////////////////////////////////////////////////////////////////////////////
987 // attach existing thread
988
989 // bootstrap the main thread
990 bool os::create_main_thread(JavaThread* thread) {
991 assert(os::Linux::_main_thread == pthread_self(), "should be called inside main thread");
992 return create_attached_thread(thread);
993 }
994
995 bool os::create_attached_thread(JavaThread* thread) {
996 #ifdef ASSERT
997 thread->verify_not_published();
998 #endif
999
1000 // Allocate the OSThread object
1001 OSThread* osthread = new OSThread(NULL, NULL);
1002
1003 if (osthread == NULL) {
1004 return false;
1005 }
1006
1007 // Store pthread info into the OSThread
1008 osthread->set_thread_id(os::Linux::gettid());
1009 osthread->set_pthread_id(::pthread_self());
1010
1011 // initialize floating point control register
1012 os::Linux::init_thread_fpu_state();
1013
1014 // Initial thread state is RUNNABLE
1015 osthread->set_state(RUNNABLE);
1016
1017 thread->set_osthread(osthread);
1018
1019 if (UseNUMA) {
1020 int lgrp_id = os::numa_get_group_id();
1021 if (lgrp_id != -1) {
1022 thread->set_lgrp_id(lgrp_id);
1023 }
1024 }
1025
1026 if (os::Linux::is_initial_thread()) {
1027 // If current thread is initial thread, its stack is mapped on demand,
1028 // see notes about MAP_GROWSDOWN. Here we try to force kernel to map
1029 // the entire stack region to avoid SEGV in stack banging.
1030 // It is also useful to get around the heap-stack-gap problem on SuSE
1031 // kernel (see 4821821 for details). We first expand stack to the top
1032 // of yellow zone, then enable stack yellow zone (order is significant,
1033 // enabling yellow zone first will crash JVM on SuSE Linux), so there
1034 // is no gap between the last two virtual memory regions.
1035
1036 JavaThread *jt = (JavaThread *)thread;
1037 address addr = jt->stack_yellow_zone_base();
1038 assert(addr != NULL, "initialization problem?");
1039 assert(jt->stack_available(addr) > 0, "stack guard should not be enabled");
1040
1041 osthread->set_expanding_stack();
1042 os::Linux::manually_expand_stack(jt, addr);
1043 osthread->clear_expanding_stack();
1044 }
1045
1046 // initialize signal mask for this thread
1047 // and save the caller's signal mask
1048 os::Linux::hotspot_sigmask(thread);
1049
1050 return true;
1051 }
1052
1053 void os::pd_start_thread(Thread* thread) {
1054 OSThread * osthread = thread->osthread();
1055 assert(osthread->get_state() != INITIALIZED, "just checking");
1056 Monitor* sync_with_child = osthread->startThread_lock();
1057 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
1058 sync_with_child->notify();
1059 }
1060
1061 // Free Linux resources related to the OSThread
1062 void os::free_thread(OSThread* osthread) {
1063 assert(osthread != NULL, "osthread not set");
1064
1065 if (Thread::current()->osthread() == osthread) {
1066 // Restore caller's signal mask
1067 sigset_t sigmask = osthread->caller_sigmask();
1068 pthread_sigmask(SIG_SETMASK, &sigmask, NULL);
1069 }
1070
1071 delete osthread;
1072 }
1073
1074 //////////////////////////////////////////////////////////////////////////////
1075 // thread local storage
1076
1077 int os::allocate_thread_local_storage() {
1078 pthread_key_t key;
1079 int rslt = pthread_key_create(&key, NULL);
1080 assert(rslt == 0, "cannot allocate thread local storage");
1081 return (int)key;
1082 }
1083
1084 // Note: This is currently not used by VM, as we don't destroy TLS key
1085 // on VM exit.
1086 void os::free_thread_local_storage(int index) {
1087 int rslt = pthread_key_delete((pthread_key_t)index);
1088 assert(rslt == 0, "invalid index");
1089 }
1090
1091 void os::thread_local_storage_at_put(int index, void* value) {
1092 int rslt = pthread_setspecific((pthread_key_t)index, value);
1093 assert(rslt == 0, "pthread_setspecific failed");
1094 }
1095
1096 extern "C" Thread* get_thread() {
1097 return ThreadLocalStorage::thread();
1098 }
1099
1100 //////////////////////////////////////////////////////////////////////////////
1101 // initial thread
1102
1103 // Check if current thread is the initial thread, similar to Solaris thr_main.
1104 bool os::Linux::is_initial_thread(void) {
1105 char dummy;
1106 // If called before init complete, thread stack bottom will be null.
1107 // Can be called if fatal error occurs before initialization.
1108 if (initial_thread_stack_bottom() == NULL) return false;
1109 assert(initial_thread_stack_bottom() != NULL &&
1110 initial_thread_stack_size() != 0,
1111 "os::init did not locate initial thread's stack region");
1112 if ((address)&dummy >= initial_thread_stack_bottom() &&
1113 (address)&dummy < initial_thread_stack_bottom() + initial_thread_stack_size())
1114 return true;
1115 else return false;
1116 }
1117
1118 // Find the virtual memory area that contains addr
1119 static bool find_vma(address addr, address* vma_low, address* vma_high) {
1120 FILE *fp = fopen("/proc/self/maps", "r");
1121 if (fp) {
1122 address low, high;
1123 while (!feof(fp)) {
1124 if (fscanf(fp, "%p-%p", &low, &high) == 2) {
1125 if (low <= addr && addr < high) {
1126 if (vma_low) *vma_low = low;
1127 if (vma_high) *vma_high = high;
1128 fclose (fp);
1129 return true;
1130 }
1131 }
1132 for (;;) {
1133 int ch = fgetc(fp);
1134 if (ch == EOF || ch == (int)'\n') break;
1135 }
1136 }
1137 fclose(fp);
1138 }
1139 return false;
1140 }
1141
1142 // Locate initial thread stack. This special handling of initial thread stack
1143 // is needed because pthread_getattr_np() on most (all?) Linux distros returns
1144 // bogus value for initial thread.
1145 void os::Linux::capture_initial_stack(size_t max_size) {
1146 // stack size is the easy part, get it from RLIMIT_STACK
1147 size_t stack_size;
1148 struct rlimit rlim;
1149 getrlimit(RLIMIT_STACK, &rlim);
1150 stack_size = rlim.rlim_cur;
1151
1152 // 6308388: a bug in ld.so will relocate its own .data section to the
1153 // lower end of primordial stack; reduce ulimit -s value a little bit
1154 // so we won't install guard page on ld.so's data section.
1155 stack_size -= 2 * page_size();
1156
1157 // 4441425: avoid crash with "unlimited" stack size on SuSE 7.1 or Redhat
1158 // 7.1, in both cases we will get 2G in return value.
1159 // 4466587: glibc 2.2.x compiled w/o "--enable-kernel=2.4.0" (RH 7.0,
1160 // SuSE 7.2, Debian) can not handle alternate signal stack correctly
1161 // for initial thread if its stack size exceeds 6M. Cap it at 2M,
1162 // in case other parts in glibc still assumes 2M max stack size.
1163 // FIXME: alt signal stack is gone, maybe we can relax this constraint?
1164 // Problem still exists RH7.2 (IA64 anyway) but 2MB is a little small
1165 if (stack_size > 2 * K * K IA64_ONLY(*2))
1166 stack_size = 2 * K * K IA64_ONLY(*2);
1167 // Try to figure out where the stack base (top) is. This is harder.
1168 //
1169 // When an application is started, glibc saves the initial stack pointer in
1170 // a global variable "__libc_stack_end", which is then used by system
1171 // libraries. __libc_stack_end should be pretty close to stack top. The
1172 // variable is available since the very early days. However, because it is
1173 // a private interface, it could disappear in the future.
1174 //
1175 // Linux kernel saves start_stack information in /proc/<pid>/stat. Similar
1176 // to __libc_stack_end, it is very close to stack top, but isn't the real
1177 // stack top. Note that /proc may not exist if VM is running as a chroot
1178 // program, so reading /proc/<pid>/stat could fail. Also the contents of
1179 // /proc/<pid>/stat could change in the future (though unlikely).
1180 //
1181 // We try __libc_stack_end first. If that doesn't work, look for
1182 // /proc/<pid>/stat. If neither of them works, we use current stack pointer
1183 // as a hint, which should work well in most cases.
1184
1185 uintptr_t stack_start;
1186
1187 // try __libc_stack_end first
1188 uintptr_t *p = (uintptr_t *)dlsym(RTLD_DEFAULT, "__libc_stack_end");
1189 if (p && *p) {
1190 stack_start = *p;
1191 } else {
1192 // see if we can get the start_stack field from /proc/self/stat
1193 FILE *fp;
1194 int pid;
1195 char state;
1196 int ppid;
1197 int pgrp;
1198 int session;
1199 int nr;
1200 int tpgrp;
1201 unsigned long flags;
1202 unsigned long minflt;
1203 unsigned long cminflt;
1204 unsigned long majflt;
1205 unsigned long cmajflt;
1206 unsigned long utime;
1207 unsigned long stime;
1208 long cutime;
1209 long cstime;
1210 long prio;
1211 long nice;
1212 long junk;
1213 long it_real;
1214 uintptr_t start;
1215 uintptr_t vsize;
1216 intptr_t rss;
1217 uintptr_t rsslim;
1218 uintptr_t scodes;
1219 uintptr_t ecode;
1220 int i;
1221
1222 // Figure what the primordial thread stack base is. Code is inspired
1223 // by email from Hans Boehm. /proc/self/stat begins with current pid,
1224 // followed by command name surrounded by parentheses, state, etc.
1225 char stat[2048];
1226 int statlen;
1227
1228 fp = fopen("/proc/self/stat", "r");
1229 if (fp) {
1230 statlen = fread(stat, 1, 2047, fp);
1231 stat[statlen] = '\0';
1232 fclose(fp);
1233
1234 // Skip pid and the command string. Note that we could be dealing with
1235 // weird command names, e.g. user could decide to rename java launcher
1236 // to "java 1.4.2 :)", then the stat file would look like
1237 // 1234 (java 1.4.2 :)) R ... ...
1238 // We don't really need to know the command string, just find the last
1239 // occurrence of ")" and then start parsing from there. See bug 4726580.
1240 char * s = strrchr(stat, ')');
1241
1242 i = 0;
1243 if (s) {
1244 // Skip blank chars
1245 do s++; while (isspace(*s));
1246
1247 #define _UFM UINTX_FORMAT
1248 #define _DFM INTX_FORMAT
1249
1250 /* 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 */
1251 /* 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 */
1252 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,
1253 &state, /* 3 %c */
1254 &ppid, /* 4 %d */
1255 &pgrp, /* 5 %d */
1256 &session, /* 6 %d */
1257 &nr, /* 7 %d */
1258 &tpgrp, /* 8 %d */
1259 &flags, /* 9 %lu */
1260 &minflt, /* 10 %lu */
1261 &cminflt, /* 11 %lu */
1262 &majflt, /* 12 %lu */
1263 &cmajflt, /* 13 %lu */
1264 &utime, /* 14 %lu */
1265 &stime, /* 15 %lu */
1266 &cutime, /* 16 %ld */
1267 &cstime, /* 17 %ld */
1268 &prio, /* 18 %ld */
1269 &nice, /* 19 %ld */
1270 &junk, /* 20 %ld */
1271 &it_real, /* 21 %ld */
1272 &start, /* 22 UINTX_FORMAT */
1273 &vsize, /* 23 UINTX_FORMAT */
1274 &rss, /* 24 INTX_FORMAT */
1275 &rsslim, /* 25 UINTX_FORMAT */
1276 &scodes, /* 26 UINTX_FORMAT */
1277 &ecode, /* 27 UINTX_FORMAT */
1278 &stack_start); /* 28 UINTX_FORMAT */
1279 }
1280
1281 #undef _UFM
1282 #undef _DFM
1283
1284 if (i != 28 - 2) {
1285 assert(false, "Bad conversion from /proc/self/stat");
1286 // product mode - assume we are the initial thread, good luck in the
1287 // embedded case.
1288 warning("Can't detect initial thread stack location - bad conversion");
1289 stack_start = (uintptr_t) &rlim;
1290 }
1291 } else {
1292 // For some reason we can't open /proc/self/stat (for example, running on
1293 // FreeBSD with a Linux emulator, or inside chroot), this should work for
1294 // most cases, so don't abort:
1295 warning("Can't detect initial thread stack location - no /proc/self/stat");
1296 stack_start = (uintptr_t) &rlim;
1297 }
1298 }
1299
1300 // Now we have a pointer (stack_start) very close to the stack top, the
1301 // next thing to do is to figure out the exact location of stack top. We
1302 // can find out the virtual memory area that contains stack_start by
1303 // reading /proc/self/maps, it should be the last vma in /proc/self/maps,
1304 // and its upper limit is the real stack top. (again, this would fail if
1305 // running inside chroot, because /proc may not exist.)
1306
1307 uintptr_t stack_top;
1308 address low, high;
1309 if (find_vma((address)stack_start, &low, &high)) {
1310 // success, "high" is the true stack top. (ignore "low", because initial
1311 // thread stack grows on demand, its real bottom is high - RLIMIT_STACK.)
1312 stack_top = (uintptr_t)high;
1313 } else {
1314 // failed, likely because /proc/self/maps does not exist
1315 warning("Can't detect initial thread stack location - find_vma failed");
1316 // best effort: stack_start is normally within a few pages below the real
1317 // stack top, use it as stack top, and reduce stack size so we won't put
1318 // guard page outside stack.
1319 stack_top = stack_start;
1320 stack_size -= 16 * page_size();
1321 }
1322
1323 // stack_top could be partially down the page so align it
1324 stack_top = align_size_up(stack_top, page_size());
1325
1326 if (max_size && stack_size > max_size) {
1327 _initial_thread_stack_size = max_size;
1328 } else {
1329 _initial_thread_stack_size = stack_size;
1330 }
1331
1332 _initial_thread_stack_size = align_size_down(_initial_thread_stack_size, page_size());
1333 _initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size;
1334 }
1335
1336 ////////////////////////////////////////////////////////////////////////////////
1337 // time support
1338
1339 // Time since start-up in seconds to a fine granularity.
1340 // Used by VMSelfDestructTimer and the MemProfiler.
1341 double os::elapsedTime() {
1342
1343 return ((double)os::elapsed_counter()) / os::elapsed_frequency(); // nanosecond resolution
1344 }
1345
1346 jlong os::elapsed_counter() {
1347 return javaTimeNanos() - initial_time_count;
1348 }
1349
1350 jlong os::elapsed_frequency() {
1351 return NANOSECS_PER_SEC; // nanosecond resolution
1352 }
1353
1354 bool os::supports_vtime() { return true; }
1355 bool os::enable_vtime() { return false; }
1356 bool os::vtime_enabled() { return false; }
1357
1358 double os::elapsedVTime() {
1359 struct rusage usage;
1360 int retval = getrusage(RUSAGE_THREAD, &usage);
1361 if (retval == 0) {
1362 return (double) (usage.ru_utime.tv_sec + usage.ru_stime.tv_sec) + (double) (usage.ru_utime.tv_usec + usage.ru_stime.tv_usec) / (1000 * 1000);
1363 } else {
1364 // better than nothing, but not much
1365 return elapsedTime();
1366 }
1367 }
1368
1369 jlong os::javaTimeMillis() {
1370 timeval time;
1371 int status = gettimeofday(&time, NULL);
1372 assert(status != -1, "linux error");
1373 return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000);
1374 }
1375
1376 #ifndef CLOCK_MONOTONIC
1377 #define CLOCK_MONOTONIC (1)
1378 #endif
1379
1380 void os::Linux::clock_init() {
1381 // we do dlopen's in this particular order due to bug in linux
1382 // dynamical loader (see 6348968) leading to crash on exit
1383 void* handle = dlopen("librt.so.1", RTLD_LAZY);
1384 if (handle == NULL) {
1385 handle = dlopen("librt.so", RTLD_LAZY);
1386 }
1387
1388 if (handle) {
1389 int (*clock_getres_func)(clockid_t, struct timespec*) =
1390 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres");
1391 int (*clock_gettime_func)(clockid_t, struct timespec*) =
1392 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime");
1393 if (clock_getres_func && clock_gettime_func) {
1394 // See if monotonic clock is supported by the kernel. Note that some
1395 // early implementations simply return kernel jiffies (updated every
1396 // 1/100 or 1/1000 second). It would be bad to use such a low res clock
1397 // for nano time (though the monotonic property is still nice to have).
1398 // It's fixed in newer kernels, however clock_getres() still returns
1399 // 1/HZ. We check if clock_getres() works, but will ignore its reported
1400 // resolution for now. Hopefully as people move to new kernels, this
1401 // won't be a problem.
1402 struct timespec res;
1403 struct timespec tp;
1404 if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 &&
1405 clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) {
1406 // yes, monotonic clock is supported
1407 _clock_gettime = clock_gettime_func;
1408 return;
1409 } else {
1410 // close librt if there is no monotonic clock
1411 dlclose(handle);
1412 }
1413 }
1414 }
1415 warning("No monotonic clock was available - timed services may " \
1416 "be adversely affected if the time-of-day clock changes");
1417 }
1418
1419 #ifndef SYS_clock_getres
1420
1421 #if defined(IA32) || defined(AMD64)
1422 #define SYS_clock_getres IA32_ONLY(266) AMD64_ONLY(229)
1423 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y)
1424 #else
1425 #warning "SYS_clock_getres not defined for this platform, disabling fast_thread_cpu_time"
1426 #define sys_clock_getres(x,y) -1
1427 #endif
1428
1429 #else
1430 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y)
1431 #endif
1432
1433 void os::Linux::fast_thread_clock_init() {
1434 if (!UseLinuxPosixThreadCPUClocks) {
1435 return;
1436 }
1437 clockid_t clockid;
1438 struct timespec tp;
1439 int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) =
1440 (int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid");
1441
1442 // Switch to using fast clocks for thread cpu time if
1443 // the sys_clock_getres() returns 0 error code.
1444 // Note, that some kernels may support the current thread
1445 // clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks
1446 // returned by the pthread_getcpuclockid().
1447 // If the fast Posix clocks are supported then the sys_clock_getres()
1448 // must return at least tp.tv_sec == 0 which means a resolution
1449 // better than 1 sec. This is extra check for reliability.
1450
1451 if(pthread_getcpuclockid_func &&
1452 pthread_getcpuclockid_func(_main_thread, &clockid) == 0 &&
1453 sys_clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) {
1454
1455 _supports_fast_thread_cpu_time = true;
1456 _pthread_getcpuclockid = pthread_getcpuclockid_func;
1457 }
1458 }
1459
1460 jlong os::javaTimeNanos() {
1461 if (os::supports_monotonic_clock()) {
1462 struct timespec tp;
1463 int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp);
1464 assert(status == 0, "gettime error");
1465 jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec);
1466 return result;
1467 } else {
1468 timeval time;
1469 int status = gettimeofday(&time, NULL);
1470 assert(status != -1, "linux error");
1471 jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec);
1472 return 1000 * usecs;
1473 }
1474 }
1475
1476 void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) {
1477 if (os::supports_monotonic_clock()) {
1478 info_ptr->max_value = ALL_64_BITS;
1479
1480 // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past
1481 info_ptr->may_skip_backward = false; // not subject to resetting or drifting
1482 info_ptr->may_skip_forward = false; // not subject to resetting or drifting
1483 } else {
1484 // gettimeofday - based on time in seconds since the Epoch thus does not wrap
1485 info_ptr->max_value = ALL_64_BITS;
1486
1487 // gettimeofday is a real time clock so it skips
1488 info_ptr->may_skip_backward = true;
1489 info_ptr->may_skip_forward = true;
1490 }
1491
1492 info_ptr->kind = JVMTI_TIMER_ELAPSED; // elapsed not CPU time
1493 }
1494
1495 // Return the real, user, and system times in seconds from an
1496 // arbitrary fixed point in the past.
1497 bool os::getTimesSecs(double* process_real_time,
1498 double* process_user_time,
1499 double* process_system_time) {
1500 struct tms ticks;
1501 clock_t real_ticks = times(&ticks);
1502
1503 if (real_ticks == (clock_t) (-1)) {
1504 return false;
1505 } else {
1506 double ticks_per_second = (double) clock_tics_per_sec;
1507 *process_user_time = ((double) ticks.tms_utime) / ticks_per_second;
1508 *process_system_time = ((double) ticks.tms_stime) / ticks_per_second;
1509 *process_real_time = ((double) real_ticks) / ticks_per_second;
1510
1511 return true;
1512 }
1513 }
1514
1515
1516 char * os::local_time_string(char *buf, size_t buflen) {
1517 struct tm t;
1518 time_t long_time;
1519 time(&long_time);
1520 localtime_r(&long_time, &t);
1521 jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d",
1522 t.tm_year + 1900, t.tm_mon + 1, t.tm_mday,
1523 t.tm_hour, t.tm_min, t.tm_sec);
1524 return buf;
1525 }
1526
1527 struct tm* os::localtime_pd(const time_t* clock, struct tm* res) {
1528 return localtime_r(clock, res);
1529 }
1530
1531 ////////////////////////////////////////////////////////////////////////////////
1532 // runtime exit support
1533
1534 // Note: os::shutdown() might be called very early during initialization, or
1535 // called from signal handler. Before adding something to os::shutdown(), make
1536 // sure it is async-safe and can handle partially initialized VM.
1537 void os::shutdown() {
1538
1539 // allow PerfMemory to attempt cleanup of any persistent resources
1540 perfMemory_exit();
1541
1542 // needs to remove object in file system
1543 AttachListener::abort();
1544
1545 // flush buffered output, finish log files
1546 ostream_abort();
1547
1548 // Check for abort hook
1549 abort_hook_t abort_hook = Arguments::abort_hook();
1550 if (abort_hook != NULL) {
1551 abort_hook();
1552 }
1553
1554 }
1555
1556 // Note: os::abort() might be called very early during initialization, or
1557 // called from signal handler. Before adding something to os::abort(), make
1558 // sure it is async-safe and can handle partially initialized VM.
1559 void os::abort(bool dump_core) {
1560 os::shutdown();
1561 if (dump_core) {
1562 #ifndef PRODUCT
1563 fdStream out(defaultStream::output_fd());
1564 out.print_raw("Current thread is ");
1565 char buf[16];
1566 jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id());
1567 out.print_raw_cr(buf);
1568 out.print_raw_cr("Dumping core ...");
1569 #endif
1570 ::abort(); // dump core
1571 }
1572
1573 ::exit(1);
1574 }
1575
1576 // Die immediately, no exit hook, no abort hook, no cleanup.
1577 void os::die() {
1578 // _exit() on LinuxThreads only kills current thread
1579 ::abort();
1580 }
1581
1582 // unused on linux for now.
1583 void os::set_error_file(const char *logfile) {}
1584
1585
1586 // This method is a copy of JDK's sysGetLastErrorString
1587 // from src/solaris/hpi/src/system_md.c
1588
1589 size_t os::lasterror(char *buf, size_t len) {
1590
1591 if (errno == 0) return 0;
1592
1593 const char *s = ::strerror(errno);
1594 size_t n = ::strlen(s);
1595 if (n >= len) {
1596 n = len - 1;
1597 }
1598 ::strncpy(buf, s, n);
1599 buf[n] = '\0';
1600 return n;
1601 }
1602
1603 intx os::current_thread_id() { return (intx)pthread_self(); }
1604 int os::current_process_id() {
1605
1606 // Under the old linux thread library, linux gives each thread
1607 // its own process id. Because of this each thread will return
1608 // a different pid if this method were to return the result
1609 // of getpid(2). Linux provides no api that returns the pid
1610 // of the launcher thread for the vm. This implementation
1611 // returns a unique pid, the pid of the launcher thread
1612 // that starts the vm 'process'.
1613
1614 // Under the NPTL, getpid() returns the same pid as the
1615 // launcher thread rather than a unique pid per thread.
1616 // Use gettid() if you want the old pre NPTL behaviour.
1617
1618 // if you are looking for the result of a call to getpid() that
1619 // returns a unique pid for the calling thread, then look at the
1620 // OSThread::thread_id() method in osThread_linux.hpp file
1621
1622 return (int)(_initial_pid ? _initial_pid : getpid());
1623 }
1624
1625 // DLL functions
1626
1627 const char* os::dll_file_extension() { return ".so"; }
1628
1629 // This must be hard coded because it's the system's temporary
1630 // directory not the java application's temp directory, ala java.io.tmpdir.
1631 const char* os::get_temp_directory() { return "/tmp"; }
1632
1633 static bool file_exists(const char* filename) {
1634 struct stat statbuf;
1635 if (filename == NULL || strlen(filename) == 0) {
1636 return false;
1637 }
1638 return os::stat(filename, &statbuf) == 0;
1639 }
1640
1641 bool os::dll_build_name(char* buffer, size_t buflen,
1642 const char* pname, const char* fname) {
1643 bool retval = false;
1644 // Copied from libhpi
1645 const size_t pnamelen = pname ? strlen(pname) : 0;
1646
1647 // Return error on buffer overflow.
1648 if (pnamelen + strlen(fname) + 10 > (size_t) buflen) {
1649 return retval;
1650 }
1651
1652 if (pnamelen == 0) {
1653 snprintf(buffer, buflen, "lib%s.so", fname);
1654 retval = true;
1655 } else if (strchr(pname, *os::path_separator()) != NULL) {
1656 int n;
1657 char** pelements = split_path(pname, &n);
1658 if (pelements == NULL) {
1659 return false;
1660 }
1661 for (int i = 0 ; i < n ; i++) {
1662 // Really shouldn't be NULL, but check can't hurt
1663 if (pelements[i] == NULL || strlen(pelements[i]) == 0) {
1664 continue; // skip the empty path values
1665 }
1666 snprintf(buffer, buflen, "%s/lib%s.so", pelements[i], fname);
1667 if (file_exists(buffer)) {
1668 retval = true;
1669 break;
1670 }
1671 }
1672 // release the storage
1673 for (int i = 0 ; i < n ; i++) {
1674 if (pelements[i] != NULL) {
1675 FREE_C_HEAP_ARRAY(char, pelements[i], mtInternal);
1676 }
1677 }
1678 if (pelements != NULL) {
1679 FREE_C_HEAP_ARRAY(char*, pelements, mtInternal);
1680 }
1681 } else {
1682 snprintf(buffer, buflen, "%s/lib%s.so", pname, fname);
1683 retval = true;
1684 }
1685 return retval;
1686 }
1687
1688 // check if addr is inside libjvm.so
1689 bool os::address_is_in_vm(address addr) {
1690 static address libjvm_base_addr;
1691 Dl_info dlinfo;
1692
1693 if (libjvm_base_addr == NULL) {
1694 if (dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo) != 0) {
1695 libjvm_base_addr = (address)dlinfo.dli_fbase;
1696 }
1697 assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm");
1698 }
1699
1700 if (dladdr((void *)addr, &dlinfo) != 0) {
1701 if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true;
1702 }
1703
1704 return false;
1705 }
1706
1707 bool os::dll_address_to_function_name(address addr, char *buf,
1708 int buflen, int *offset) {
1709 // buf is not optional, but offset is optional
1710 assert(buf != NULL, "sanity check");
1711
1712 Dl_info dlinfo;
1713
1714 if (dladdr((void*)addr, &dlinfo) != 0) {
1715 // see if we have a matching symbol
1716 if (dlinfo.dli_saddr != NULL && dlinfo.dli_sname != NULL) {
1717 if (!Decoder::demangle(dlinfo.dli_sname, buf, buflen)) {
1718 jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname);
1719 }
1720 if (offset != NULL) *offset = addr - (address)dlinfo.dli_saddr;
1721 return true;
1722 }
1723 // no matching symbol so try for just file info
1724 if (dlinfo.dli_fname != NULL && dlinfo.dli_fbase != NULL) {
1725 if (Decoder::decode((address)(addr - (address)dlinfo.dli_fbase),
1726 buf, buflen, offset, dlinfo.dli_fname)) {
1727 return true;
1728 }
1729 }
1730 }
1731
1732 buf[0] = '\0';
1733 if (offset != NULL) *offset = -1;
1734 return false;
1735 }
1736
1737 struct _address_to_library_name {
1738 address addr; // input : memory address
1739 size_t buflen; // size of fname
1740 char* fname; // output: library name
1741 address base; // library base addr
1742 };
1743
1744 static int address_to_library_name_callback(struct dl_phdr_info *info,
1745 size_t size, void *data) {
1746 int i;
1747 bool found = false;
1748 address libbase = NULL;
1749 struct _address_to_library_name * d = (struct _address_to_library_name *)data;
1750
1751 // iterate through all loadable segments
1752 for (i = 0; i < info->dlpi_phnum; i++) {
1753 address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr);
1754 if (info->dlpi_phdr[i].p_type == PT_LOAD) {
1755 // base address of a library is the lowest address of its loaded
1756 // segments.
1757 if (libbase == NULL || libbase > segbase) {
1758 libbase = segbase;
1759 }
1760 // see if 'addr' is within current segment
1761 if (segbase <= d->addr &&
1762 d->addr < segbase + info->dlpi_phdr[i].p_memsz) {
1763 found = true;
1764 }
1765 }
1766 }
1767
1768 // dlpi_name is NULL or empty if the ELF file is executable, return 0
1769 // so dll_address_to_library_name() can fall through to use dladdr() which
1770 // can figure out executable name from argv[0].
1771 if (found && info->dlpi_name && info->dlpi_name[0]) {
1772 d->base = libbase;
1773 if (d->fname) {
1774 jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name);
1775 }
1776 return 1;
1777 }
1778 return 0;
1779 }
1780
1781 bool os::dll_address_to_library_name(address addr, char* buf,
1782 int buflen, int* offset) {
1783 // buf is not optional, but offset is optional
1784 assert(buf != NULL, "sanity check");
1785
1786 Dl_info dlinfo;
1787 struct _address_to_library_name data;
1788
1789 // There is a bug in old glibc dladdr() implementation that it could resolve
1790 // to wrong library name if the .so file has a base address != NULL. Here
1791 // we iterate through the program headers of all loaded libraries to find
1792 // out which library 'addr' really belongs to. This workaround can be
1793 // removed once the minimum requirement for glibc is moved to 2.3.x.
1794 data.addr = addr;
1795 data.fname = buf;
1796 data.buflen = buflen;
1797 data.base = NULL;
1798 int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data);
1799
1800 if (rslt) {
1801 // buf already contains library name
1802 if (offset) *offset = addr - data.base;
1803 return true;
1804 }
1805 if (dladdr((void*)addr, &dlinfo) != 0) {
1806 if (dlinfo.dli_fname != NULL) {
1807 jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname);
1808 }
1809 if (dlinfo.dli_fbase != NULL && offset != NULL) {
1810 *offset = addr - (address)dlinfo.dli_fbase;
1811 }
1812 return true;
1813 }
1814
1815 buf[0] = '\0';
1816 if (offset) *offset = -1;
1817 return false;
1818 }
1819
1820 // Loads .dll/.so and
1821 // in case of error it checks if .dll/.so was built for the
1822 // same architecture as Hotspot is running on
1823
1824
1825 // Remember the stack's state. The Linux dynamic linker will change
1826 // the stack to 'executable' at most once, so we must safepoint only once.
1827 bool os::Linux::_stack_is_executable = false;
1828
1829 // VM operation that loads a library. This is necessary if stack protection
1830 // of the Java stacks can be lost during loading the library. If we
1831 // do not stop the Java threads, they can stack overflow before the stacks
1832 // are protected again.
1833 class VM_LinuxDllLoad: public VM_Operation {
1834 private:
1835 const char *_filename;
1836 char *_ebuf;
1837 int _ebuflen;
1838 void *_lib;
1839 public:
1840 VM_LinuxDllLoad(const char *fn, char *ebuf, int ebuflen) :
1841 _filename(fn), _ebuf(ebuf), _ebuflen(ebuflen), _lib(NULL) {}
1842 VMOp_Type type() const { return VMOp_LinuxDllLoad; }
1843 void doit() {
1844 _lib = os::Linux::dll_load_in_vmthread(_filename, _ebuf, _ebuflen);
1845 os::Linux::_stack_is_executable = true;
1846 }
1847 void* loaded_library() { return _lib; }
1848 };
1849
1850 void * os::dll_load(const char *filename, char *ebuf, int ebuflen)
1851 {
1852 void * result = NULL;
1853 bool load_attempted = false;
1854
1855 // Check whether the library to load might change execution rights
1856 // of the stack. If they are changed, the protection of the stack
1857 // guard pages will be lost. We need a safepoint to fix this.
1858 //
1859 // See Linux man page execstack(8) for more info.
1860 if (os::uses_stack_guard_pages() && !os::Linux::_stack_is_executable) {
1861 ElfFile ef(filename);
1862 if (!ef.specifies_noexecstack()) {
1863 if (!is_init_completed()) {
1864 os::Linux::_stack_is_executable = true;
1865 // This is OK - No Java threads have been created yet, and hence no
1866 // stack guard pages to fix.
1867 //
1868 // This should happen only when you are building JDK7 using a very
1869 // old version of JDK6 (e.g., with JPRT) and running test_gamma.
1870 //
1871 // Dynamic loader will make all stacks executable after
1872 // this function returns, and will not do that again.
1873 assert(Threads::first() == NULL, "no Java threads should exist yet.");
1874 } else {
1875 warning("You have loaded library %s which might have disabled stack guard. "
1876 "The VM will try to fix the stack guard now.\n"
1877 "It's highly recommended that you fix the library with "
1878 "'execstack -c <libfile>', or link it with '-z noexecstack'.",
1879 filename);
1880
1881 assert(Thread::current()->is_Java_thread(), "must be Java thread");
1882 JavaThread *jt = JavaThread::current();
1883 if (jt->thread_state() != _thread_in_native) {
1884 // This happens when a compiler thread tries to load a hsdis-<arch>.so file
1885 // that requires ExecStack. Cannot enter safe point. Let's give up.
1886 warning("Unable to fix stack guard. Giving up.");
1887 } else {
1888 if (!LoadExecStackDllInVMThread) {
1889 // This is for the case where the DLL has an static
1890 // constructor function that executes JNI code. We cannot
1891 // load such DLLs in the VMThread.
1892 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen);
1893 }
1894
1895 ThreadInVMfromNative tiv(jt);
1896 debug_only(VMNativeEntryWrapper vew;)
1897
1898 VM_LinuxDllLoad op(filename, ebuf, ebuflen);
1899 VMThread::execute(&op);
1900 if (LoadExecStackDllInVMThread) {
1901 result = op.loaded_library();
1902 }
1903 load_attempted = true;
1904 }
1905 }
1906 }
1907 }
1908
1909 if (!load_attempted) {
1910 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen);
1911 }
1912
1913 if (result != NULL) {
1914 // Successful loading
1915 return result;
1916 }
1917
1918 Elf32_Ehdr elf_head;
1919 int diag_msg_max_length=ebuflen-strlen(ebuf);
1920 char* diag_msg_buf=ebuf+strlen(ebuf);
1921
1922 if (diag_msg_max_length==0) {
1923 // No more space in ebuf for additional diagnostics message
1924 return NULL;
1925 }
1926
1927
1928 int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK);
1929
1930 if (file_descriptor < 0) {
1931 // Can't open library, report dlerror() message
1932 return NULL;
1933 }
1934
1935 bool failed_to_read_elf_head=
1936 (sizeof(elf_head)!=
1937 (::read(file_descriptor, &elf_head,sizeof(elf_head)))) ;
1938
1939 ::close(file_descriptor);
1940 if (failed_to_read_elf_head) {
1941 // file i/o error - report dlerror() msg
1942 return NULL;
1943 }
1944
1945 typedef struct {
1946 Elf32_Half code; // Actual value as defined in elf.h
1947 Elf32_Half compat_class; // Compatibility of archs at VM's sense
1948 char elf_class; // 32 or 64 bit
1949 char endianess; // MSB or LSB
1950 char* name; // String representation
1951 } arch_t;
1952
1953 #ifndef EM_486
1954 #define EM_486 6 /* Intel 80486 */
1955 #endif
1956
1957 static const arch_t arch_array[]={
1958 {EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
1959 {EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
1960 {EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"},
1961 {EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"},
1962 {EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
1963 {EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
1964 {EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"},
1965 {EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"},
1966 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"},
1967 {EM_ARM, EM_ARM, ELFCLASS32, ELFDATA2LSB, (char*)"ARM"},
1968 {EM_S390, EM_S390, ELFCLASSNONE, ELFDATA2MSB, (char*)"IBM System/390"},
1969 {EM_ALPHA, EM_ALPHA, ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"},
1970 {EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"},
1971 {EM_MIPS, EM_MIPS, ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"},
1972 {EM_PARISC, EM_PARISC, ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"},
1973 {EM_68K, EM_68K, ELFCLASS32, ELFDATA2MSB, (char*)"M68k"}
1974 };
1975
1976 #if (defined IA32)
1977 static Elf32_Half running_arch_code=EM_386;
1978 #elif (defined AMD64)
1979 static Elf32_Half running_arch_code=EM_X86_64;
1980 #elif (defined IA64)
1981 static Elf32_Half running_arch_code=EM_IA_64;
1982 #elif (defined __sparc) && (defined _LP64)
1983 static Elf32_Half running_arch_code=EM_SPARCV9;
1984 #elif (defined __sparc) && (!defined _LP64)
1985 static Elf32_Half running_arch_code=EM_SPARC;
1986 #elif (defined __powerpc64__)
1987 static Elf32_Half running_arch_code=EM_PPC64;
1988 #elif (defined __powerpc__)
1989 static Elf32_Half running_arch_code=EM_PPC;
1990 #elif (defined ARM)
1991 static Elf32_Half running_arch_code=EM_ARM;
1992 #elif (defined S390)
1993 static Elf32_Half running_arch_code=EM_S390;
1994 #elif (defined ALPHA)
1995 static Elf32_Half running_arch_code=EM_ALPHA;
1996 #elif (defined MIPSEL)
1997 static Elf32_Half running_arch_code=EM_MIPS_RS3_LE;
1998 #elif (defined PARISC)
1999 static Elf32_Half running_arch_code=EM_PARISC;
2000 #elif (defined MIPS)
2001 static Elf32_Half running_arch_code=EM_MIPS;
2002 #elif (defined M68K)
2003 static Elf32_Half running_arch_code=EM_68K;
2004 #else
2005 #error Method os::dll_load requires that one of following is defined:\
2006 IA32, AMD64, IA64, __sparc, __powerpc__, ARM, S390, ALPHA, MIPS, MIPSEL, PARISC, M68K
2007 #endif
2008
2009 // Identify compatability class for VM's architecture and library's architecture
2010 // Obtain string descriptions for architectures
2011
2012 arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL};
2013 int running_arch_index=-1;
2014
2015 for (unsigned int i=0 ; i < ARRAY_SIZE(arch_array) ; i++ ) {
2016 if (running_arch_code == arch_array[i].code) {
2017 running_arch_index = i;
2018 }
2019 if (lib_arch.code == arch_array[i].code) {
2020 lib_arch.compat_class = arch_array[i].compat_class;
2021 lib_arch.name = arch_array[i].name;
2022 }
2023 }
2024
2025 assert(running_arch_index != -1,
2026 "Didn't find running architecture code (running_arch_code) in arch_array");
2027 if (running_arch_index == -1) {
2028 // Even though running architecture detection failed
2029 // we may still continue with reporting dlerror() message
2030 return NULL;
2031 }
2032
2033 if (lib_arch.endianess != arch_array[running_arch_index].endianess) {
2034 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)");
2035 return NULL;
2036 }
2037
2038 #ifndef S390
2039 if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) {
2040 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)");
2041 return NULL;
2042 }
2043 #endif // !S390
2044
2045 if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) {
2046 if ( lib_arch.name!=NULL ) {
2047 ::snprintf(diag_msg_buf, diag_msg_max_length-1,
2048 " (Possible cause: can't load %s-bit .so on a %s-bit platform)",
2049 lib_arch.name, arch_array[running_arch_index].name);
2050 } else {
2051 ::snprintf(diag_msg_buf, diag_msg_max_length-1,
2052 " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)",
2053 lib_arch.code,
2054 arch_array[running_arch_index].name);
2055 }
2056 }
2057
2058 return NULL;
2059 }
2060
2061 void * os::Linux::dlopen_helper(const char *filename, char *ebuf, int ebuflen) {
2062 void * result = ::dlopen(filename, RTLD_LAZY);
2063 if (result == NULL) {
2064 ::strncpy(ebuf, ::dlerror(), ebuflen - 1);
2065 ebuf[ebuflen-1] = '\0';
2066 }
2067 return result;
2068 }
2069
2070 void * os::Linux::dll_load_in_vmthread(const char *filename, char *ebuf, int ebuflen) {
2071 void * result = NULL;
2072 if (LoadExecStackDllInVMThread) {
2073 result = dlopen_helper(filename, ebuf, ebuflen);
2074 }
2075
2076 // Since 7019808, libjvm.so is linked with -noexecstack. If the VM loads a
2077 // library that requires an executable stack, or which does not have this
2078 // stack attribute set, dlopen changes the stack attribute to executable. The
2079 // read protection of the guard pages gets lost.
2080 //
2081 // Need to check _stack_is_executable again as multiple VM_LinuxDllLoad
2082 // may have been queued at the same time.
2083
2084 if (!_stack_is_executable) {
2085 JavaThread *jt = Threads::first();
2086
2087 while (jt) {
2088 if (!jt->stack_guard_zone_unused() && // Stack not yet fully initialized
2089 jt->stack_yellow_zone_enabled()) { // No pending stack overflow exceptions
2090 if (!os::guard_memory((char *) jt->stack_red_zone_base() - jt->stack_red_zone_size(),
2091 jt->stack_yellow_zone_size() + jt->stack_red_zone_size())) {
2092 warning("Attempt to reguard stack yellow zone failed.");
2093 }
2094 }
2095 jt = jt->next();
2096 }
2097 }
2098
2099 return result;
2100 }
2101
2102 /*
2103 * glibc-2.0 libdl is not MT safe. If you are building with any glibc,
2104 * chances are you might want to run the generated bits against glibc-2.0
2105 * libdl.so, so always use locking for any version of glibc.
2106 */
2107 void* os::dll_lookup(void* handle, const char* name) {
2108 pthread_mutex_lock(&dl_mutex);
2109 void* res = dlsym(handle, name);
2110 pthread_mutex_unlock(&dl_mutex);
2111 return res;
2112 }
2113
2114 void* os::get_default_process_handle() {
2115 return (void*)::dlopen(NULL, RTLD_LAZY);
2116 }
2117
2118 static bool _print_ascii_file(const char* filename, outputStream* st) {
2119 int fd = ::open(filename, O_RDONLY);
2120 if (fd == -1) {
2121 return false;
2122 }
2123
2124 char buf[32];
2125 int bytes;
2126 while ((bytes = ::read(fd, buf, sizeof(buf))) > 0) {
2127 st->print_raw(buf, bytes);
2128 }
2129
2130 ::close(fd);
2131
2132 return true;
2133 }
2134
2135 void os::print_dll_info(outputStream *st) {
2136 st->print_cr("Dynamic libraries:");
2137
2138 char fname[32];
2139 pid_t pid = os::Linux::gettid();
2140
2141 jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid);
2142
2143 if (!_print_ascii_file(fname, st)) {
2144 st->print("Can not get library information for pid = %d\n", pid);
2145 }
2146 }
2147
2148 void os::print_os_info_brief(outputStream* st) {
2149 os::Linux::print_distro_info(st);
2150
2151 os::Posix::print_uname_info(st);
2152
2153 os::Linux::print_libversion_info(st);
2154
2155 }
2156
2157 void os::print_os_info(outputStream* st) {
2158 st->print("OS:");
2159
2160 os::Linux::print_distro_info(st);
2161
2162 os::Posix::print_uname_info(st);
2163
2164 // Print warning if unsafe chroot environment detected
2165 if (unsafe_chroot_detected) {
2166 st->print("WARNING!! ");
2167 st->print_cr(unstable_chroot_error);
2168 }
2169
2170 os::Linux::print_libversion_info(st);
2171
2172 os::Posix::print_rlimit_info(st);
2173
2174 os::Posix::print_load_average(st);
2175
2176 os::Linux::print_full_memory_info(st);
2177 }
2178
2179 // Try to identify popular distros.
2180 // Most Linux distributions have a /etc/XXX-release file, which contains
2181 // the OS version string. Newer Linux distributions have a /etc/lsb-release
2182 // file that also contains the OS version string. Some have more than one
2183 // /etc/XXX-release file (e.g. Mandrake has both /etc/mandrake-release and
2184 // /etc/redhat-release.), so the order is important.
2185 // Any Linux that is based on Redhat (i.e. Oracle, Mandrake, Sun JDS...) have
2186 // their own specific XXX-release file as well as a redhat-release file.
2187 // Because of this the XXX-release file needs to be searched for before the
2188 // redhat-release file.
2189 // Since Red Hat has a lsb-release file that is not very descriptive the
2190 // search for redhat-release needs to be before lsb-release.
2191 // Since the lsb-release file is the new standard it needs to be searched
2192 // before the older style release files.
2193 // Searching system-release (Red Hat) and os-release (other Linuxes) are a
2194 // next to last resort. The os-release file is a new standard that contains
2195 // distribution information and the system-release file seems to be an old
2196 // standard that has been replaced by the lsb-release and os-release files.
2197 // Searching for the debian_version file is the last resort. It contains
2198 // an informative string like "6.0.6" or "wheezy/sid". Because of this
2199 // "Debian " is printed before the contents of the debian_version file.
2200 void os::Linux::print_distro_info(outputStream* st) {
2201 if (!_print_ascii_file("/etc/oracle-release", st) &&
2202 !_print_ascii_file("/etc/mandriva-release", st) &&
2203 !_print_ascii_file("/etc/mandrake-release", st) &&
2204 !_print_ascii_file("/etc/sun-release", st) &&
2205 !_print_ascii_file("/etc/redhat-release", st) &&
2206 !_print_ascii_file("/etc/lsb-release", st) &&
2207 !_print_ascii_file("/etc/SuSE-release", st) &&
2208 !_print_ascii_file("/etc/turbolinux-release", st) &&
2209 !_print_ascii_file("/etc/gentoo-release", st) &&
2210 !_print_ascii_file("/etc/ltib-release", st) &&
2211 !_print_ascii_file("/etc/angstrom-version", st) &&
2212 !_print_ascii_file("/etc/system-release", st) &&
2213 !_print_ascii_file("/etc/os-release", st)) {
2214
2215 if (file_exists("/etc/debian_version")) {
2216 st->print("Debian ");
2217 _print_ascii_file("/etc/debian_version", st);
2218 } else {
2219 st->print("Linux");
2220 }
2221 }
2222 st->cr();
2223 }
2224
2225 void os::Linux::print_libversion_info(outputStream* st) {
2226 // libc, pthread
2227 st->print("libc:");
2228 st->print(os::Linux::glibc_version()); st->print(" ");
2229 st->print(os::Linux::libpthread_version()); st->print(" ");
2230 if (os::Linux::is_LinuxThreads()) {
2231 st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed");
2232 }
2233 st->cr();
2234 }
2235
2236 void os::Linux::print_full_memory_info(outputStream* st) {
2237 st->print("\n/proc/meminfo:\n");
2238 _print_ascii_file("/proc/meminfo", st);
2239 st->cr();
2240 }
2241
2242 void os::print_memory_info(outputStream* st) {
2243
2244 st->print("Memory:");
2245 st->print(" %dk page", os::vm_page_size()>>10);
2246
2247 // values in struct sysinfo are "unsigned long"
2248 struct sysinfo si;
2249 sysinfo(&si);
2250
2251 st->print(", physical " UINT64_FORMAT "k",
2252 os::physical_memory() >> 10);
2253 st->print("(" UINT64_FORMAT "k free)",
2254 os::available_memory() >> 10);
2255 st->print(", swap " UINT64_FORMAT "k",
2256 ((jlong)si.totalswap * si.mem_unit) >> 10);
2257 st->print("(" UINT64_FORMAT "k free)",
2258 ((jlong)si.freeswap * si.mem_unit) >> 10);
2259 st->cr();
2260 }
2261
2262 void os::pd_print_cpu_info(outputStream* st) {
2263 st->print("\n/proc/cpuinfo:\n");
2264 if (!_print_ascii_file("/proc/cpuinfo", st)) {
2265 st->print(" <Not Available>");
2266 }
2267 st->cr();
2268 }
2269
2270 void os::print_siginfo(outputStream* st, void* siginfo) {
2271 const siginfo_t* si = (const siginfo_t*)siginfo;
2272
2273 os::Posix::print_siginfo_brief(st, si);
2274
2275 if (si && (si->si_signo == SIGBUS || si->si_signo == SIGSEGV) &&
2276 UseSharedSpaces) {
2277 FileMapInfo* mapinfo = FileMapInfo::current_info();
2278 if (mapinfo->is_in_shared_space(si->si_addr)) {
2279 st->print("\n\nError accessing class data sharing archive." \
2280 " Mapped file inaccessible during execution, " \
2281 " possible disk/network problem.");
2282 }
2283 }
2284 st->cr();
2285 }
2286
2287
2288 static void print_signal_handler(outputStream* st, int sig,
2289 char* buf, size_t buflen);
2290
2291 void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) {
2292 st->print_cr("Signal Handlers:");
2293 print_signal_handler(st, SIGSEGV, buf, buflen);
2294 print_signal_handler(st, SIGBUS , buf, buflen);
2295 print_signal_handler(st, SIGFPE , buf, buflen);
2296 print_signal_handler(st, SIGPIPE, buf, buflen);
2297 print_signal_handler(st, SIGXFSZ, buf, buflen);
2298 print_signal_handler(st, SIGILL , buf, buflen);
2299 print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen);
2300 print_signal_handler(st, SR_signum, buf, buflen);
2301 print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen);
2302 print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen);
2303 print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen);
2304 print_signal_handler(st, BREAK_SIGNAL, buf, buflen);
2305 #if defined(PPC64)
2306 print_signal_handler(st, SIGTRAP, buf, buflen);
2307 #endif
2308 }
2309
2310 static char saved_jvm_path[MAXPATHLEN] = {0};
2311
2312 // Find the full path to the current module, libjvm.so
2313 void os::jvm_path(char *buf, jint buflen) {
2314 // Error checking.
2315 if (buflen < MAXPATHLEN) {
2316 assert(false, "must use a large-enough buffer");
2317 buf[0] = '\0';
2318 return;
2319 }
2320 // Lazy resolve the path to current module.
2321 if (saved_jvm_path[0] != 0) {
2322 strcpy(buf, saved_jvm_path);
2323 return;
2324 }
2325
2326 char dli_fname[MAXPATHLEN];
2327 bool ret = dll_address_to_library_name(
2328 CAST_FROM_FN_PTR(address, os::jvm_path),
2329 dli_fname, sizeof(dli_fname), NULL);
2330 assert(ret, "cannot locate libjvm");
2331 char *rp = NULL;
2332 if (ret && dli_fname[0] != '\0') {
2333 rp = realpath(dli_fname, buf);
2334 }
2335 if (rp == NULL)
2336 return;
2337
2338 if (Arguments::sun_java_launcher_is_altjvm()) {
2339 // Support for the java launcher's '-XXaltjvm=<path>' option. Typical
2340 // value for buf is "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so".
2341 // If "/jre/lib/" appears at the right place in the string, then
2342 // assume we are installed in a JDK and we're done. Otherwise, check
2343 // for a JAVA_HOME environment variable and fix up the path so it
2344 // looks like libjvm.so is installed there (append a fake suffix
2345 // hotspot/libjvm.so).
2346 const char *p = buf + strlen(buf) - 1;
2347 for (int count = 0; p > buf && count < 5; ++count) {
2348 for (--p; p > buf && *p != '/'; --p)
2349 /* empty */ ;
2350 }
2351
2352 if (strncmp(p, "/jre/lib/", 9) != 0) {
2353 // Look for JAVA_HOME in the environment.
2354 char* java_home_var = ::getenv("JAVA_HOME");
2355 if (java_home_var != NULL && java_home_var[0] != 0) {
2356 char* jrelib_p;
2357 int len;
2358
2359 // Check the current module name "libjvm.so".
2360 p = strrchr(buf, '/');
2361 assert(strstr(p, "/libjvm") == p, "invalid library name");
2362
2363 rp = realpath(java_home_var, buf);
2364 if (rp == NULL)
2365 return;
2366
2367 // determine if this is a legacy image or modules image
2368 // modules image doesn't have "jre" subdirectory
2369 len = strlen(buf);
2370 jrelib_p = buf + len;
2371 snprintf(jrelib_p, buflen-len, "/jre/lib/%s", cpu_arch);
2372 if (0 != access(buf, F_OK)) {
2373 snprintf(jrelib_p, buflen-len, "/lib/%s", cpu_arch);
2374 }
2375
2376 if (0 == access(buf, F_OK)) {
2377 // Use current module name "libjvm.so"
2378 len = strlen(buf);
2379 snprintf(buf + len, buflen-len, "/hotspot/libjvm.so");
2380 } else {
2381 // Go back to path of .so
2382 rp = realpath(dli_fname, buf);
2383 if (rp == NULL)
2384 return;
2385 }
2386 }
2387 }
2388 }
2389
2390 strcpy(saved_jvm_path, buf);
2391 }
2392
2393 void os::print_jni_name_prefix_on(outputStream* st, int args_size) {
2394 // no prefix required, not even "_"
2395 }
2396
2397 void os::print_jni_name_suffix_on(outputStream* st, int args_size) {
2398 // no suffix required
2399 }
2400
2401 ////////////////////////////////////////////////////////////////////////////////
2402 // sun.misc.Signal support
2403
2404 static volatile jint sigint_count = 0;
2405
2406 static void
2407 UserHandler(int sig, void *siginfo, void *context) {
2408 // 4511530 - sem_post is serialized and handled by the manager thread. When
2409 // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We
2410 // don't want to flood the manager thread with sem_post requests.
2411 if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1)
2412 return;
2413
2414 // Ctrl-C is pressed during error reporting, likely because the error
2415 // handler fails to abort. Let VM die immediately.
2416 if (sig == SIGINT && is_error_reported()) {
2417 os::die();
2418 }
2419
2420 os::signal_notify(sig);
2421 }
2422
2423 void* os::user_handler() {
2424 return CAST_FROM_FN_PTR(void*, UserHandler);
2425 }
2426
2427 class Semaphore : public StackObj {
2428 public:
2429 Semaphore();
2430 ~Semaphore();
2431 void signal();
2432 void wait();
2433 bool trywait();
2434 bool timedwait(unsigned int sec, int nsec);
2435 private:
2436 sem_t _semaphore;
2437 };
2438
2439 Semaphore::Semaphore() {
2440 sem_init(&_semaphore, 0, 0);
2441 }
2442
2443 Semaphore::~Semaphore() {
2444 sem_destroy(&_semaphore);
2445 }
2446
2447 void Semaphore::signal() {
2448 sem_post(&_semaphore);
2449 }
2450
2451 void Semaphore::wait() {
2452 sem_wait(&_semaphore);
2453 }
2454
2455 bool Semaphore::trywait() {
2456 return sem_trywait(&_semaphore) == 0;
2457 }
2458
2459 bool Semaphore::timedwait(unsigned int sec, int nsec) {
2460
2461 struct timespec ts;
2462 // Semaphore's are always associated with CLOCK_REALTIME
2463 os::Linux::clock_gettime(CLOCK_REALTIME, &ts);
2464 // see unpackTime for discussion on overflow checking
2465 if (sec >= MAX_SECS) {
2466 ts.tv_sec += MAX_SECS;
2467 ts.tv_nsec = 0;
2468 } else {
2469 ts.tv_sec += sec;
2470 ts.tv_nsec += nsec;
2471 if (ts.tv_nsec >= NANOSECS_PER_SEC) {
2472 ts.tv_nsec -= NANOSECS_PER_SEC;
2473 ++ts.tv_sec; // note: this must be <= max_secs
2474 }
2475 }
2476
2477 while (1) {
2478 int result = sem_timedwait(&_semaphore, &ts);
2479 if (result == 0) {
2480 return true;
2481 } else if (errno == EINTR) {
2482 continue;
2483 } else if (errno == ETIMEDOUT) {
2484 return false;
2485 } else {
2486 return false;
2487 }
2488 }
2489 }
2490
2491 extern "C" {
2492 typedef void (*sa_handler_t)(int);
2493 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *);
2494 }
2495
2496 void* os::signal(int signal_number, void* handler) {
2497 struct sigaction sigAct, oldSigAct;
2498
2499 sigfillset(&(sigAct.sa_mask));
2500 sigAct.sa_flags = SA_RESTART|SA_SIGINFO;
2501 sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler);
2502
2503 if (sigaction(signal_number, &sigAct, &oldSigAct)) {
2504 // -1 means registration failed
2505 return (void *)-1;
2506 }
2507
2508 return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler);
2509 }
2510
2511 void os::signal_raise(int signal_number) {
2512 ::raise(signal_number);
2513 }
2514
2515 /*
2516 * The following code is moved from os.cpp for making this
2517 * code platform specific, which it is by its very nature.
2518 */
2519
2520 // Will be modified when max signal is changed to be dynamic
2521 int os::sigexitnum_pd() {
2522 return NSIG;
2523 }
2524
2525 // a counter for each possible signal value
2526 static volatile jint pending_signals[NSIG+1] = { 0 };
2527
2528 // Linux(POSIX) specific hand shaking semaphore.
2529 static sem_t sig_sem;
2530 static Semaphore sr_semaphore;
2531
2532 void os::signal_init_pd() {
2533 // Initialize signal structures
2534 ::memset((void*)pending_signals, 0, sizeof(pending_signals));
2535
2536 // Initialize signal semaphore
2537 ::sem_init(&sig_sem, 0, 0);
2538 }
2539
2540 void os::signal_notify(int sig) {
2541 Atomic::inc(&pending_signals[sig]);
2542 ::sem_post(&sig_sem);
2543 }
2544
2545 static int check_pending_signals(bool wait) {
2546 Atomic::store(0, &sigint_count);
2547 for (;;) {
2548 for (int i = 0; i < NSIG + 1; i++) {
2549 jint n = pending_signals[i];
2550 if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) {
2551 return i;
2552 }
2553 }
2554 if (!wait) {
2555 return -1;
2556 }
2557 JavaThread *thread = JavaThread::current();
2558 ThreadBlockInVM tbivm(thread);
2559
2560 bool threadIsSuspended;
2561 do {
2562 thread->set_suspend_equivalent();
2563 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
2564 ::sem_wait(&sig_sem);
2565
2566 // were we externally suspended while we were waiting?
2567 threadIsSuspended = thread->handle_special_suspend_equivalent_condition();
2568 if (threadIsSuspended) {
2569 //
2570 // The semaphore has been incremented, but while we were waiting
2571 // another thread suspended us. We don't want to continue running
2572 // while suspended because that would surprise the thread that
2573 // suspended us.
2574 //
2575 ::sem_post(&sig_sem);
2576
2577 thread->java_suspend_self();
2578 }
2579 } while (threadIsSuspended);
2580 }
2581 }
2582
2583 int os::signal_lookup() {
2584 return check_pending_signals(false);
2585 }
2586
2587 int os::signal_wait() {
2588 return check_pending_signals(true);
2589 }
2590
2591 ////////////////////////////////////////////////////////////////////////////////
2592 // Virtual Memory
2593
2594 int os::vm_page_size() {
2595 // Seems redundant as all get out
2596 assert(os::Linux::page_size() != -1, "must call os::init");
2597 return os::Linux::page_size();
2598 }
2599
2600 // Solaris allocates memory by pages.
2601 int os::vm_allocation_granularity() {
2602 assert(os::Linux::page_size() != -1, "must call os::init");
2603 return os::Linux::page_size();
2604 }
2605
2606 // Rationale behind this function:
2607 // current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable
2608 // mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get
2609 // samples for JITted code. Here we create private executable mapping over the code cache
2610 // and then we can use standard (well, almost, as mapping can change) way to provide
2611 // info for the reporting script by storing timestamp and location of symbol
2612 void linux_wrap_code(char* base, size_t size) {
2613 static volatile jint cnt = 0;
2614
2615 if (!UseOprofile) {
2616 return;
2617 }
2618
2619 char buf[PATH_MAX+1];
2620 int num = Atomic::add(1, &cnt);
2621
2622 snprintf(buf, sizeof(buf), "%s/hs-vm-%d-%d",
2623 os::get_temp_directory(), os::current_process_id(), num);
2624 unlink(buf);
2625
2626 int fd = ::open(buf, O_CREAT | O_RDWR, S_IRWXU);
2627
2628 if (fd != -1) {
2629 off_t rv = ::lseek(fd, size-2, SEEK_SET);
2630 if (rv != (off_t)-1) {
2631 if (::write(fd, "", 1) == 1) {
2632 mmap(base, size,
2633 PROT_READ|PROT_WRITE|PROT_EXEC,
2634 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0);
2635 }
2636 }
2637 ::close(fd);
2638 unlink(buf);
2639 }
2640 }
2641
2642 static bool recoverable_mmap_error(int err) {
2643 // See if the error is one we can let the caller handle. This
2644 // list of errno values comes from JBS-6843484. I can't find a
2645 // Linux man page that documents this specific set of errno
2646 // values so while this list currently matches Solaris, it may
2647 // change as we gain experience with this failure mode.
2648 switch (err) {
2649 case EBADF:
2650 case EINVAL:
2651 case ENOTSUP:
2652 // let the caller deal with these errors
2653 return true;
2654
2655 default:
2656 // Any remaining errors on this OS can cause our reserved mapping
2657 // to be lost. That can cause confusion where different data
2658 // structures think they have the same memory mapped. The worst
2659 // scenario is if both the VM and a library think they have the
2660 // same memory mapped.
2661 return false;
2662 }
2663 }
2664
2665 static void warn_fail_commit_memory(char* addr, size_t size, bool exec,
2666 int err) {
2667 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT
2668 ", %d) failed; error='%s' (errno=%d)", addr, size, exec,
2669 strerror(err), err);
2670 }
2671
2672 static void warn_fail_commit_memory(char* addr, size_t size,
2673 size_t alignment_hint, bool exec,
2674 int err) {
2675 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT
2676 ", " SIZE_FORMAT ", %d) failed; error='%s' (errno=%d)", addr, size,
2677 alignment_hint, exec, strerror(err), err);
2678 }
2679
2680 // NOTE: Linux kernel does not really reserve the pages for us.
2681 // All it does is to check if there are enough free pages
2682 // left at the time of mmap(). This could be a potential
2683 // problem.
2684 int os::Linux::commit_memory_impl(char* addr, size_t size, bool exec) {
2685 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
2686 uintptr_t res = (uintptr_t) ::mmap(addr, size, prot,
2687 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0);
2688 if (res != (uintptr_t) MAP_FAILED) {
2689 if (UseNUMAInterleaving) {
2690 numa_make_global(addr, size);
2691 }
2692 return 0;
2693 }
2694
2695 int err = errno; // save errno from mmap() call above
2696
2697 if (!recoverable_mmap_error(err)) {
2698 warn_fail_commit_memory(addr, size, exec, err);
2699 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, "committing reserved memory.");
2700 }
2701
2702 return err;
2703 }
2704
2705 bool os::pd_commit_memory(char* addr, size_t size, bool exec) {
2706 return os::Linux::commit_memory_impl(addr, size, exec) == 0;
2707 }
2708
2709 void os::pd_commit_memory_or_exit(char* addr, size_t size, bool exec,
2710 const char* mesg) {
2711 assert(mesg != NULL, "mesg must be specified");
2712 int err = os::Linux::commit_memory_impl(addr, size, exec);
2713 if (err != 0) {
2714 // the caller wants all commit errors to exit with the specified mesg:
2715 warn_fail_commit_memory(addr, size, exec, err);
2716 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg);
2717 }
2718 }
2719
2720 // Define MAP_HUGETLB here so we can build HotSpot on old systems.
2721 #ifndef MAP_HUGETLB
2722 #define MAP_HUGETLB 0x40000
2723 #endif
2724
2725 // Define MADV_HUGEPAGE here so we can build HotSpot on old systems.
2726 #ifndef MADV_HUGEPAGE
2727 #define MADV_HUGEPAGE 14
2728 #endif
2729
2730 int os::Linux::commit_memory_impl(char* addr, size_t size,
2731 size_t alignment_hint, bool exec) {
2732 int err = os::Linux::commit_memory_impl(addr, size, exec);
2733 if (err == 0) {
2734 realign_memory(addr, size, alignment_hint);
2735 }
2736 return err;
2737 }
2738
2739 bool os::pd_commit_memory(char* addr, size_t size, size_t alignment_hint,
2740 bool exec) {
2741 return os::Linux::commit_memory_impl(addr, size, alignment_hint, exec) == 0;
2742 }
2743
2744 void os::pd_commit_memory_or_exit(char* addr, size_t size,
2745 size_t alignment_hint, bool exec,
2746 const char* mesg) {
2747 assert(mesg != NULL, "mesg must be specified");
2748 int err = os::Linux::commit_memory_impl(addr, size, alignment_hint, exec);
2749 if (err != 0) {
2750 // the caller wants all commit errors to exit with the specified mesg:
2751 warn_fail_commit_memory(addr, size, alignment_hint, exec, err);
2752 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg);
2753 }
2754 }
2755
2756 void os::pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint) {
2757 if (UseTransparentHugePages && alignment_hint > (size_t)vm_page_size()) {
2758 // We don't check the return value: madvise(MADV_HUGEPAGE) may not
2759 // be supported or the memory may already be backed by huge pages.
2760 ::madvise(addr, bytes, MADV_HUGEPAGE);
2761 }
2762 }
2763
2764 void os::pd_free_memory(char *addr, size_t bytes, size_t alignment_hint) {
2765 // This method works by doing an mmap over an existing mmaping and effectively discarding
2766 // the existing pages. However it won't work for SHM-based large pages that cannot be
2767 // uncommitted at all. We don't do anything in this case to avoid creating a segment with
2768 // small pages on top of the SHM segment. This method always works for small pages, so we
2769 // allow that in any case.
2770 if (alignment_hint <= (size_t)os::vm_page_size() || can_commit_large_page_memory()) {
2771 commit_memory(addr, bytes, alignment_hint, !ExecMem);
2772 }
2773 }
2774
2775 void os::numa_make_global(char *addr, size_t bytes) {
2776 Linux::numa_interleave_memory(addr, bytes);
2777 }
2778
2779 // Define for numa_set_bind_policy(int). Setting the argument to 0 will set the
2780 // bind policy to MPOL_PREFERRED for the current thread.
2781 #define USE_MPOL_PREFERRED 0
2782
2783 void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) {
2784 // To make NUMA and large pages more robust when both enabled, we need to ease
2785 // the requirements on where the memory should be allocated. MPOL_BIND is the
2786 // default policy and it will force memory to be allocated on the specified
2787 // node. Changing this to MPOL_PREFERRED will prefer to allocate the memory on
2788 // the specified node, but will not force it. Using this policy will prevent
2789 // getting SIGBUS when trying to allocate large pages on NUMA nodes with no
2790 // free large pages.
2791 Linux::numa_set_bind_policy(USE_MPOL_PREFERRED);
2792 Linux::numa_tonode_memory(addr, bytes, lgrp_hint);
2793 }
2794
2795 bool os::numa_topology_changed() { return false; }
2796
2797 size_t os::numa_get_groups_num() {
2798 int max_node = Linux::numa_max_node();
2799 return max_node > 0 ? max_node + 1 : 1;
2800 }
2801
2802 int os::numa_get_group_id() {
2803 int cpu_id = Linux::sched_getcpu();
2804 if (cpu_id != -1) {
2805 int lgrp_id = Linux::get_node_by_cpu(cpu_id);
2806 if (lgrp_id != -1) {
2807 return lgrp_id;
2808 }
2809 }
2810 return 0;
2811 }
2812
2813 size_t os::numa_get_leaf_groups(int *ids, size_t size) {
2814 for (size_t i = 0; i < size; i++) {
2815 ids[i] = i;
2816 }
2817 return size;
2818 }
2819
2820 bool os::get_page_info(char *start, page_info* info) {
2821 return false;
2822 }
2823
2824 char *os::scan_pages(char *start, char* end, page_info* page_expected, page_info* page_found) {
2825 return end;
2826 }
2827
2828
2829 int os::Linux::sched_getcpu_syscall(void) {
2830 unsigned int cpu;
2831 int retval = -1;
2832
2833 #if defined(IA32)
2834 # ifndef SYS_getcpu
2835 # define SYS_getcpu 318
2836 # endif
2837 retval = syscall(SYS_getcpu, &cpu, NULL, NULL);
2838 #elif defined(AMD64)
2839 // Unfortunately we have to bring all these macros here from vsyscall.h
2840 // to be able to compile on old linuxes.
2841 # define __NR_vgetcpu 2
2842 # define VSYSCALL_START (-10UL << 20)
2843 # define VSYSCALL_SIZE 1024
2844 # define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr))
2845 typedef long (*vgetcpu_t)(unsigned int *cpu, unsigned int *node, unsigned long *tcache);
2846 vgetcpu_t vgetcpu = (vgetcpu_t)VSYSCALL_ADDR(__NR_vgetcpu);
2847 retval = vgetcpu(&cpu, NULL, NULL);
2848 #endif
2849
2850 return (retval == -1) ? retval : cpu;
2851 }
2852
2853 // Something to do with the numa-aware allocator needs these symbols
2854 extern "C" JNIEXPORT void numa_warn(int number, char *where, ...) { }
2855 extern "C" JNIEXPORT void numa_error(char *where) { }
2856 extern "C" JNIEXPORT int fork1() { return fork(); }
2857
2858
2859 // If we are running with libnuma version > 2, then we should
2860 // be trying to use symbols with versions 1.1
2861 // If we are running with earlier version, which did not have symbol versions,
2862 // we should use the base version.
2863 void* os::Linux::libnuma_dlsym(void* handle, const char *name) {
2864 void *f = dlvsym(handle, name, "libnuma_1.1");
2865 if (f == NULL) {
2866 f = dlsym(handle, name);
2867 }
2868 return f;
2869 }
2870
2871 bool os::Linux::libnuma_init() {
2872 // sched_getcpu() should be in libc.
2873 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t,
2874 dlsym(RTLD_DEFAULT, "sched_getcpu")));
2875
2876 // If it's not, try a direct syscall.
2877 if (sched_getcpu() == -1)
2878 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, (void*)&sched_getcpu_syscall));
2879
2880 if (sched_getcpu() != -1) { // Does it work?
2881 void *handle = dlopen("libnuma.so.1", RTLD_LAZY);
2882 if (handle != NULL) {
2883 set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t,
2884 libnuma_dlsym(handle, "numa_node_to_cpus")));
2885 set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t,
2886 libnuma_dlsym(handle, "numa_max_node")));
2887 set_numa_available(CAST_TO_FN_PTR(numa_available_func_t,
2888 libnuma_dlsym(handle, "numa_available")));
2889 set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t,
2890 libnuma_dlsym(handle, "numa_tonode_memory")));
2891 set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t,
2892 libnuma_dlsym(handle, "numa_interleave_memory")));
2893 set_numa_set_bind_policy(CAST_TO_FN_PTR(numa_set_bind_policy_func_t,
2894 libnuma_dlsym(handle, "numa_set_bind_policy")));
2895
2896
2897 if (numa_available() != -1) {
2898 set_numa_all_nodes((unsigned long*)libnuma_dlsym(handle, "numa_all_nodes"));
2899 // Create a cpu -> node mapping
2900 _cpu_to_node = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<int>(0, true);
2901 rebuild_cpu_to_node_map();
2902 return true;
2903 }
2904 }
2905 }
2906 return false;
2907 }
2908
2909 // rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id.
2910 // The table is later used in get_node_by_cpu().
2911 void os::Linux::rebuild_cpu_to_node_map() {
2912 const size_t NCPUS = 32768; // Since the buffer size computation is very obscure
2913 // in libnuma (possible values are starting from 16,
2914 // and continuing up with every other power of 2, but less
2915 // than the maximum number of CPUs supported by kernel), and
2916 // is a subject to change (in libnuma version 2 the requirements
2917 // are more reasonable) we'll just hardcode the number they use
2918 // in the library.
2919 const size_t BitsPerCLong = sizeof(long) * CHAR_BIT;
2920
2921 size_t cpu_num = os::active_processor_count();
2922 size_t cpu_map_size = NCPUS / BitsPerCLong;
2923 size_t cpu_map_valid_size =
2924 MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size);
2925
2926 cpu_to_node()->clear();
2927 cpu_to_node()->at_grow(cpu_num - 1);
2928 size_t node_num = numa_get_groups_num();
2929
2930 unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size, mtInternal);
2931 for (size_t i = 0; i < node_num; i++) {
2932 if (numa_node_to_cpus(i, cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) {
2933 for (size_t j = 0; j < cpu_map_valid_size; j++) {
2934 if (cpu_map[j] != 0) {
2935 for (size_t k = 0; k < BitsPerCLong; k++) {
2936 if (cpu_map[j] & (1UL << k)) {
2937 cpu_to_node()->at_put(j * BitsPerCLong + k, i);
2938 }
2939 }
2940 }
2941 }
2942 }
2943 }
2944 FREE_C_HEAP_ARRAY(unsigned long, cpu_map, mtInternal);
2945 }
2946
2947 int os::Linux::get_node_by_cpu(int cpu_id) {
2948 if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) {
2949 return cpu_to_node()->at(cpu_id);
2950 }
2951 return -1;
2952 }
2953
2954 GrowableArray<int>* os::Linux::_cpu_to_node;
2955 os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu;
2956 os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus;
2957 os::Linux::numa_max_node_func_t os::Linux::_numa_max_node;
2958 os::Linux::numa_available_func_t os::Linux::_numa_available;
2959 os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory;
2960 os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory;
2961 os::Linux::numa_set_bind_policy_func_t os::Linux::_numa_set_bind_policy;
2962 unsigned long* os::Linux::_numa_all_nodes;
2963
2964 bool os::pd_uncommit_memory(char* addr, size_t size) {
2965 uintptr_t res = (uintptr_t) ::mmap(addr, size, PROT_NONE,
2966 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0);
2967 return res != (uintptr_t) MAP_FAILED;
2968 }
2969
2970 static
2971 address get_stack_commited_bottom(address bottom, size_t size) {
2972 address nbot = bottom;
2973 address ntop = bottom + size;
2974
2975 size_t page_sz = os::vm_page_size();
2976 unsigned pages = size / page_sz;
2977
2978 unsigned char vec[1];
2979 unsigned imin = 1, imax = pages + 1, imid;
2980 int mincore_return_value = 0;
2981
2982 assert(imin <= imax, "Unexpected page size");
2983
2984 while (imin < imax) {
2985 imid = (imax + imin) / 2;
2986 nbot = ntop - (imid * page_sz);
2987
2988 // Use a trick with mincore to check whether the page is mapped or not.
2989 // mincore sets vec to 1 if page resides in memory and to 0 if page
2990 // is swapped output but if page we are asking for is unmapped
2991 // it returns -1,ENOMEM
2992 mincore_return_value = mincore(nbot, page_sz, vec);
2993
2994 if (mincore_return_value == -1) {
2995 // Page is not mapped go up
2996 // to find first mapped page
2997 if (errno != EAGAIN) {
2998 assert(errno == ENOMEM, "Unexpected mincore errno");
2999 imax = imid;
3000 }
3001 } else {
3002 // Page is mapped go down
3003 // to find first not mapped page
3004 imin = imid + 1;
3005 }
3006 }
3007
3008 nbot = nbot + page_sz;
3009
3010 // Adjust stack bottom one page up if last checked page is not mapped
3011 if (mincore_return_value == -1) {
3012 nbot = nbot + page_sz;
3013 }
3014
3015 return nbot;
3016 }
3017
3018
3019 // Linux uses a growable mapping for the stack, and if the mapping for
3020 // the stack guard pages is not removed when we detach a thread the
3021 // stack cannot grow beyond the pages where the stack guard was
3022 // mapped. If at some point later in the process the stack expands to
3023 // that point, the Linux kernel cannot expand the stack any further
3024 // because the guard pages are in the way, and a segfault occurs.
3025 //
3026 // However, it's essential not to split the stack region by unmapping
3027 // a region (leaving a hole) that's already part of the stack mapping,
3028 // so if the stack mapping has already grown beyond the guard pages at
3029 // the time we create them, we have to truncate the stack mapping.
3030 // So, we need to know the extent of the stack mapping when
3031 // create_stack_guard_pages() is called.
3032
3033 // We only need this for stacks that are growable: at the time of
3034 // writing thread stacks don't use growable mappings (i.e. those
3035 // creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this
3036 // only applies to the main thread.
3037
3038 // If the (growable) stack mapping already extends beyond the point
3039 // where we're going to put our guard pages, truncate the mapping at
3040 // that point by munmap()ping it. This ensures that when we later
3041 // munmap() the guard pages we don't leave a hole in the stack
3042 // mapping. This only affects the main/initial thread
3043
3044 bool os::pd_create_stack_guard_pages(char* addr, size_t size) {
3045
3046 if (os::Linux::is_initial_thread()) {
3047 // As we manually grow stack up to bottom inside create_attached_thread(),
3048 // it's likely that os::Linux::initial_thread_stack_bottom is mapped and
3049 // we don't need to do anything special.
3050 // Check it first, before calling heavy function.
3051 uintptr_t stack_extent = (uintptr_t) os::Linux::initial_thread_stack_bottom();
3052 unsigned char vec[1];
3053
3054 if (mincore((address)stack_extent, os::vm_page_size(), vec) == -1) {
3055 // Fallback to slow path on all errors, including EAGAIN
3056 stack_extent = (uintptr_t) get_stack_commited_bottom(
3057 os::Linux::initial_thread_stack_bottom(),
3058 (size_t)addr - stack_extent);
3059 }
3060
3061 if (stack_extent < (uintptr_t)addr) {
3062 ::munmap((void*)stack_extent, (uintptr_t)(addr - stack_extent));
3063 }
3064 }
3065
3066 return os::commit_memory(addr, size, !ExecMem);
3067 }
3068
3069 // If this is a growable mapping, remove the guard pages entirely by
3070 // munmap()ping them. If not, just call uncommit_memory(). This only
3071 // affects the main/initial thread, but guard against future OS changes
3072 // It's safe to always unmap guard pages for initial thread because we
3073 // always place it right after end of the mapped region
3074
3075 bool os::remove_stack_guard_pages(char* addr, size_t size) {
3076 uintptr_t stack_extent, stack_base;
3077
3078 if (os::Linux::is_initial_thread()) {
3079 return ::munmap(addr, size) == 0;
3080 }
3081
3082 return os::uncommit_memory(addr, size);
3083 }
3084
3085 static address _highest_vm_reserved_address = NULL;
3086
3087 // If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory
3088 // at 'requested_addr'. If there are existing memory mappings at the same
3089 // location, however, they will be overwritten. If 'fixed' is false,
3090 // 'requested_addr' is only treated as a hint, the return value may or
3091 // may not start from the requested address. Unlike Linux mmap(), this
3092 // function returns NULL to indicate failure.
3093 static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) {
3094 char * addr;
3095 int flags;
3096
3097 flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS;
3098 if (fixed) {
3099 assert((uintptr_t)requested_addr % os::Linux::page_size() == 0, "unaligned address");
3100 flags |= MAP_FIXED;
3101 }
3102
3103 // Map reserved/uncommitted pages PROT_NONE so we fail early if we
3104 // touch an uncommitted page. Otherwise, the read/write might
3105 // succeed if we have enough swap space to back the physical page.
3106 addr = (char*)::mmap(requested_addr, bytes, PROT_NONE,
3107 flags, -1, 0);
3108
3109 if (addr != MAP_FAILED) {
3110 // anon_mmap() should only get called during VM initialization,
3111 // don't need lock (actually we can skip locking even it can be called
3112 // from multiple threads, because _highest_vm_reserved_address is just a
3113 // hint about the upper limit of non-stack memory regions.)
3114 if ((address)addr + bytes > _highest_vm_reserved_address) {
3115 _highest_vm_reserved_address = (address)addr + bytes;
3116 }
3117 }
3118
3119 return addr == MAP_FAILED ? NULL : addr;
3120 }
3121
3122 // Don't update _highest_vm_reserved_address, because there might be memory
3123 // regions above addr + size. If so, releasing a memory region only creates
3124 // a hole in the address space, it doesn't help prevent heap-stack collision.
3125 //
3126 static int anon_munmap(char * addr, size_t size) {
3127 return ::munmap(addr, size) == 0;
3128 }
3129
3130 char* os::pd_reserve_memory(size_t bytes, char* requested_addr,
3131 size_t alignment_hint) {
3132 return anon_mmap(requested_addr, bytes, (requested_addr != NULL));
3133 }
3134
3135 bool os::pd_release_memory(char* addr, size_t size) {
3136 return anon_munmap(addr, size);
3137 }
3138
3139 static address highest_vm_reserved_address() {
3140 return _highest_vm_reserved_address;
3141 }
3142
3143 static bool linux_mprotect(char* addr, size_t size, int prot) {
3144 // Linux wants the mprotect address argument to be page aligned.
3145 char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::page_size());
3146
3147 // According to SUSv3, mprotect() should only be used with mappings
3148 // established by mmap(), and mmap() always maps whole pages. Unaligned
3149 // 'addr' likely indicates problem in the VM (e.g. trying to change
3150 // protection of malloc'ed or statically allocated memory). Check the
3151 // caller if you hit this assert.
3152 assert(addr == bottom, "sanity check");
3153
3154 size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Linux::page_size());
3155 return ::mprotect(bottom, size, prot) == 0;
3156 }
3157
3158 // Set protections specified
3159 bool os::protect_memory(char* addr, size_t bytes, ProtType prot,
3160 bool is_committed) {
3161 unsigned int p = 0;
3162 switch (prot) {
3163 case MEM_PROT_NONE: p = PROT_NONE; break;
3164 case MEM_PROT_READ: p = PROT_READ; break;
3165 case MEM_PROT_RW: p = PROT_READ|PROT_WRITE; break;
3166 case MEM_PROT_RWX: p = PROT_READ|PROT_WRITE|PROT_EXEC; break;
3167 default:
3168 ShouldNotReachHere();
3169 }
3170 // is_committed is unused.
3171 return linux_mprotect(addr, bytes, p);
3172 }
3173
3174 bool os::guard_memory(char* addr, size_t size) {
3175 return linux_mprotect(addr, size, PROT_NONE);
3176 }
3177
3178 bool os::unguard_memory(char* addr, size_t size) {
3179 return linux_mprotect(addr, size, PROT_READ|PROT_WRITE);
3180 }
3181
3182 bool os::Linux::transparent_huge_pages_sanity_check(bool warn, size_t page_size) {
3183 bool result = false;
3184 void *p = mmap(NULL, page_size * 2, PROT_READ|PROT_WRITE,
3185 MAP_ANONYMOUS|MAP_PRIVATE,
3186 -1, 0);
3187 if (p != MAP_FAILED) {
3188 void *aligned_p = align_ptr_up(p, page_size);
3189
3190 result = madvise(aligned_p, page_size, MADV_HUGEPAGE) == 0;
3191
3192 munmap(p, page_size * 2);
3193 }
3194
3195 if (warn && !result) {
3196 warning("TransparentHugePages is not supported by the operating system.");
3197 }
3198
3199 return result;
3200 }
3201
3202 bool os::Linux::hugetlbfs_sanity_check(bool warn, size_t page_size) {
3203 bool result = false;
3204 void *p = mmap(NULL, page_size, PROT_READ|PROT_WRITE,
3205 MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB,
3206 -1, 0);
3207
3208 if (p != MAP_FAILED) {
3209 // We don't know if this really is a huge page or not.
3210 FILE *fp = fopen("/proc/self/maps", "r");
3211 if (fp) {
3212 while (!feof(fp)) {
3213 char chars[257];
3214 long x = 0;
3215 if (fgets(chars, sizeof(chars), fp)) {
3216 if (sscanf(chars, "%lx-%*x", &x) == 1
3217 && x == (long)p) {
3218 if (strstr (chars, "hugepage")) {
3219 result = true;
3220 break;
3221 }
3222 }
3223 }
3224 }
3225 fclose(fp);
3226 }
3227 munmap(p, page_size);
3228 }
3229
3230 if (warn && !result) {
3231 warning("HugeTLBFS is not supported by the operating system.");
3232 }
3233
3234 return result;
3235 }
3236
3237 /*
3238 * Set the coredump_filter bits to include largepages in core dump (bit 6)
3239 *
3240 * From the coredump_filter documentation:
3241 *
3242 * - (bit 0) anonymous private memory
3243 * - (bit 1) anonymous shared memory
3244 * - (bit 2) file-backed private memory
3245 * - (bit 3) file-backed shared memory
3246 * - (bit 4) ELF header pages in file-backed private memory areas (it is
3247 * effective only if the bit 2 is cleared)
3248 * - (bit 5) hugetlb private memory
3249 * - (bit 6) hugetlb shared memory
3250 */
3251 static void set_coredump_filter(void) {
3252 FILE *f;
3253 long cdm;
3254
3255 if ((f = fopen("/proc/self/coredump_filter", "r+")) == NULL) {
3256 return;
3257 }
3258
3259 if (fscanf(f, "%lx", &cdm) != 1) {
3260 fclose(f);
3261 return;
3262 }
3263
3264 rewind(f);
3265
3266 if ((cdm & LARGEPAGES_BIT) == 0) {
3267 cdm |= LARGEPAGES_BIT;
3268 fprintf(f, "%#lx", cdm);
3269 }
3270
3271 fclose(f);
3272 }
3273
3274 // Large page support
3275
3276 static size_t _large_page_size = 0;
3277
3278 size_t os::Linux::find_large_page_size() {
3279 size_t large_page_size = 0;
3280
3281 // large_page_size on Linux is used to round up heap size. x86 uses either
3282 // 2M or 4M page, depending on whether PAE (Physical Address Extensions)
3283 // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use
3284 // page as large as 256M.
3285 //
3286 // Here we try to figure out page size by parsing /proc/meminfo and looking
3287 // for a line with the following format:
3288 // Hugepagesize: 2048 kB
3289 //
3290 // If we can't determine the value (e.g. /proc is not mounted, or the text
3291 // format has been changed), we'll use the largest page size supported by
3292 // the processor.
3293
3294 #ifndef ZERO
3295 large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M)
3296 ARM_ONLY(2 * M) PPC_ONLY(4 * M);
3297 #endif // ZERO
3298
3299 FILE *fp = fopen("/proc/meminfo", "r");
3300 if (fp) {
3301 while (!feof(fp)) {
3302 int x = 0;
3303 char buf[16];
3304 if (fscanf(fp, "Hugepagesize: %d", &x) == 1) {
3305 if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) {
3306 large_page_size = x * K;
3307 break;
3308 }
3309 } else {
3310 // skip to next line
3311 for (;;) {
3312 int ch = fgetc(fp);
3313 if (ch == EOF || ch == (int)'\n') break;
3314 }
3315 }
3316 }
3317 fclose(fp);
3318 }
3319
3320 if (!FLAG_IS_DEFAULT(LargePageSizeInBytes) && LargePageSizeInBytes != large_page_size) {
3321 warning("Setting LargePageSizeInBytes has no effect on this OS. Large page size is "
3322 SIZE_FORMAT "%s.", byte_size_in_proper_unit(large_page_size),
3323 proper_unit_for_byte_size(large_page_size));
3324 }
3325
3326 return large_page_size;
3327 }
3328
3329 size_t os::Linux::setup_large_page_size() {
3330 _large_page_size = Linux::find_large_page_size();
3331 const size_t default_page_size = (size_t)Linux::page_size();
3332 if (_large_page_size > default_page_size) {
3333 _page_sizes[0] = _large_page_size;
3334 _page_sizes[1] = default_page_size;
3335 _page_sizes[2] = 0;
3336 }
3337
3338 return _large_page_size;
3339 }
3340
3341 bool os::Linux::setup_large_page_type(size_t page_size) {
3342 if (FLAG_IS_DEFAULT(UseHugeTLBFS) &&
3343 FLAG_IS_DEFAULT(UseSHM) &&
3344 FLAG_IS_DEFAULT(UseTransparentHugePages)) {
3345
3346 // The type of large pages has not been specified by the user.
3347
3348 // Try UseHugeTLBFS and then UseSHM.
3349 UseHugeTLBFS = UseSHM = true;
3350
3351 // Don't try UseTransparentHugePages since there are known
3352 // performance issues with it turned on. This might change in the future.
3353 UseTransparentHugePages = false;
3354 }
3355
3356 if (UseTransparentHugePages) {
3357 bool warn_on_failure = !FLAG_IS_DEFAULT(UseTransparentHugePages);
3358 if (transparent_huge_pages_sanity_check(warn_on_failure, page_size)) {
3359 UseHugeTLBFS = false;
3360 UseSHM = false;
3361 return true;
3362 }
3363 UseTransparentHugePages = false;
3364 }
3365
3366 if (UseHugeTLBFS) {
3367 bool warn_on_failure = !FLAG_IS_DEFAULT(UseHugeTLBFS);
3368 if (hugetlbfs_sanity_check(warn_on_failure, page_size)) {
3369 UseSHM = false;
3370 return true;
3371 }
3372 UseHugeTLBFS = false;
3373 }
3374
3375 return UseSHM;
3376 }
3377
3378 void os::large_page_init() {
3379 if (!UseLargePages &&
3380 !UseTransparentHugePages &&
3381 !UseHugeTLBFS &&
3382 !UseSHM) {
3383 // Not using large pages.
3384 return;
3385 }
3386
3387 if (!FLAG_IS_DEFAULT(UseLargePages) && !UseLargePages) {
3388 // The user explicitly turned off large pages.
3389 // Ignore the rest of the large pages flags.
3390 UseTransparentHugePages = false;
3391 UseHugeTLBFS = false;
3392 UseSHM = false;
3393 return;
3394 }
3395
3396 size_t large_page_size = Linux::setup_large_page_size();
3397 UseLargePages = Linux::setup_large_page_type(large_page_size);
3398
3399 set_coredump_filter();
3400 }
3401
3402 #ifndef SHM_HUGETLB
3403 #define SHM_HUGETLB 04000
3404 #endif
3405
3406 char* os::Linux::reserve_memory_special_shm(size_t bytes, size_t alignment, char* req_addr, bool exec) {
3407 // "exec" is passed in but not used. Creating the shared image for
3408 // the code cache doesn't have an SHM_X executable permission to check.
3409 assert(UseLargePages && UseSHM, "only for SHM large pages");
3410 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address");
3411
3412 if (!is_size_aligned(bytes, os::large_page_size()) || alignment > os::large_page_size()) {
3413 return NULL; // Fallback to small pages.
3414 }
3415
3416 key_t key = IPC_PRIVATE;
3417 char *addr;
3418
3419 bool warn_on_failure = UseLargePages &&
3420 (!FLAG_IS_DEFAULT(UseLargePages) ||
3421 !FLAG_IS_DEFAULT(UseSHM) ||
3422 !FLAG_IS_DEFAULT(LargePageSizeInBytes)
3423 );
3424 char msg[128];
3425
3426 // Create a large shared memory region to attach to based on size.
3427 // Currently, size is the total size of the heap
3428 int shmid = shmget(key, bytes, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W);
3429 if (shmid == -1) {
3430 // Possible reasons for shmget failure:
3431 // 1. shmmax is too small for Java heap.
3432 // > check shmmax value: cat /proc/sys/kernel/shmmax
3433 // > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax
3434 // 2. not enough large page memory.
3435 // > check available large pages: cat /proc/meminfo
3436 // > increase amount of large pages:
3437 // echo new_value > /proc/sys/vm/nr_hugepages
3438 // Note 1: different Linux may use different name for this property,
3439 // e.g. on Redhat AS-3 it is "hugetlb_pool".
3440 // Note 2: it's possible there's enough physical memory available but
3441 // they are so fragmented after a long run that they can't
3442 // coalesce into large pages. Try to reserve large pages when
3443 // the system is still "fresh".
3444 if (warn_on_failure) {
3445 jio_snprintf(msg, sizeof(msg), "Failed to reserve shared memory (errno = %d).", errno);
3446 warning(msg);
3447 }
3448 return NULL;
3449 }
3450
3451 // attach to the region
3452 addr = (char*)shmat(shmid, req_addr, 0);
3453 int err = errno;
3454
3455 // Remove shmid. If shmat() is successful, the actual shared memory segment
3456 // will be deleted when it's detached by shmdt() or when the process
3457 // terminates. If shmat() is not successful this will remove the shared
3458 // segment immediately.
3459 shmctl(shmid, IPC_RMID, NULL);
3460
3461 if ((intptr_t)addr == -1) {
3462 if (warn_on_failure) {
3463 jio_snprintf(msg, sizeof(msg), "Failed to attach shared memory (errno = %d).", err);
3464 warning(msg);
3465 }
3466 return NULL;
3467 }
3468
3469 return addr;
3470 }
3471
3472 static void warn_on_large_pages_failure(char* req_addr, size_t bytes, int error) {
3473 assert(error == ENOMEM, "Only expect to fail if no memory is available");
3474
3475 bool warn_on_failure = UseLargePages &&
3476 (!FLAG_IS_DEFAULT(UseLargePages) ||
3477 !FLAG_IS_DEFAULT(UseHugeTLBFS) ||
3478 !FLAG_IS_DEFAULT(LargePageSizeInBytes));
3479
3480 if (warn_on_failure) {
3481 char msg[128];
3482 jio_snprintf(msg, sizeof(msg), "Failed to reserve large pages memory req_addr: "
3483 PTR_FORMAT " bytes: " SIZE_FORMAT " (errno = %d).", req_addr, bytes, error);
3484 warning(msg);
3485 }
3486 }
3487
3488 char* os::Linux::reserve_memory_special_huge_tlbfs_only(size_t bytes, char* req_addr, bool exec) {
3489 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages");
3490 assert(is_size_aligned(bytes, os::large_page_size()), "Unaligned size");
3491 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address");
3492
3493 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
3494 char* addr = (char*)::mmap(req_addr, bytes, prot,
3495 MAP_PRIVATE|MAP_ANONYMOUS|MAP_HUGETLB,
3496 -1, 0);
3497
3498 if (addr == MAP_FAILED) {
3499 warn_on_large_pages_failure(req_addr, bytes, errno);
3500 return NULL;
3501 }
3502
3503 assert(is_ptr_aligned(addr, os::large_page_size()), "Must be");
3504
3505 return addr;
3506 }
3507
3508 char* os::Linux::reserve_memory_special_huge_tlbfs_mixed(size_t bytes, size_t alignment, char* req_addr, bool exec) {
3509 size_t large_page_size = os::large_page_size();
3510
3511 assert(bytes >= large_page_size, "Shouldn't allocate large pages for small sizes");
3512
3513 // Allocate small pages.
3514
3515 char* start;
3516 if (req_addr != NULL) {
3517 assert(is_ptr_aligned(req_addr, alignment), "Must be");
3518 assert(is_size_aligned(bytes, alignment), "Must be");
3519 start = os::reserve_memory(bytes, req_addr);
3520 assert(start == NULL || start == req_addr, "Must be");
3521 } else {
3522 start = os::reserve_memory_aligned(bytes, alignment);
3523 }
3524
3525 if (start == NULL) {
3526 return NULL;
3527 }
3528
3529 assert(is_ptr_aligned(start, alignment), "Must be");
3530
3531 // os::reserve_memory_special will record this memory area.
3532 // Need to release it here to prevent overlapping reservations.
3533 MemTracker::record_virtual_memory_release((address)start, bytes);
3534
3535 char* end = start + bytes;
3536
3537 // Find the regions of the allocated chunk that can be promoted to large pages.
3538 char* lp_start = (char*)align_ptr_up(start, large_page_size);
3539 char* lp_end = (char*)align_ptr_down(end, large_page_size);
3540
3541 size_t lp_bytes = lp_end - lp_start;
3542
3543 assert(is_size_aligned(lp_bytes, large_page_size), "Must be");
3544
3545 if (lp_bytes == 0) {
3546 // The mapped region doesn't even span the start and the end of a large page.
3547 // Fall back to allocate a non-special area.
3548 ::munmap(start, end - start);
3549 return NULL;
3550 }
3551
3552 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
3553
3554
3555 void* result;
3556
3557 if (start != lp_start) {
3558 result = ::mmap(start, lp_start - start, prot,
3559 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED,
3560 -1, 0);
3561 if (result == MAP_FAILED) {
3562 ::munmap(lp_start, end - lp_start);
3563 return NULL;
3564 }
3565 }
3566
3567 result = ::mmap(lp_start, lp_bytes, prot,
3568 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED|MAP_HUGETLB,
3569 -1, 0);
3570 if (result == MAP_FAILED) {
3571 warn_on_large_pages_failure(req_addr, bytes, errno);
3572 // If the mmap above fails, the large pages region will be unmapped and we
3573 // have regions before and after with small pages. Release these regions.
3574 //
3575 // | mapped | unmapped | mapped |
3576 // ^ ^ ^ ^
3577 // start lp_start lp_end end
3578 //
3579 ::munmap(start, lp_start - start);
3580 ::munmap(lp_end, end - lp_end);
3581 return NULL;
3582 }
3583
3584 if (lp_end != end) {
3585 result = ::mmap(lp_end, end - lp_end, prot,
3586 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED,
3587 -1, 0);
3588 if (result == MAP_FAILED) {
3589 ::munmap(start, lp_end - start);
3590 return NULL;
3591 }
3592 }
3593
3594 return start;
3595 }
3596
3597 char* os::Linux::reserve_memory_special_huge_tlbfs(size_t bytes, size_t alignment, char* req_addr, bool exec) {
3598 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages");
3599 assert(is_ptr_aligned(req_addr, alignment), "Must be");
3600 assert(is_power_of_2(alignment), "Must be");
3601 assert(is_power_of_2(os::large_page_size()), "Must be");
3602 assert(bytes >= os::large_page_size(), "Shouldn't allocate large pages for small sizes");
3603
3604 if (is_size_aligned(bytes, os::large_page_size()) && alignment <= os::large_page_size()) {
3605 return reserve_memory_special_huge_tlbfs_only(bytes, req_addr, exec);
3606 } else {
3607 return reserve_memory_special_huge_tlbfs_mixed(bytes, alignment, req_addr, exec);
3608 }
3609 }
3610
3611 char* os::reserve_memory_special(size_t bytes, size_t alignment, char* req_addr, bool exec) {
3612 assert(UseLargePages, "only for large pages");
3613
3614 char* addr;
3615 if (UseSHM) {
3616 addr = os::Linux::reserve_memory_special_shm(bytes, alignment, req_addr, exec);
3617 } else {
3618 assert(UseHugeTLBFS, "must be");
3619 addr = os::Linux::reserve_memory_special_huge_tlbfs(bytes, alignment, req_addr, exec);
3620 }
3621
3622 if (addr != NULL) {
3623 if (UseNUMAInterleaving) {
3624 numa_make_global(addr, bytes);
3625 }
3626
3627 // The memory is committed
3628 MemTracker::record_virtual_memory_reserve_and_commit((address)addr, bytes, mtNone, CALLER_PC);
3629 }
3630
3631 return addr;
3632 }
3633
3634 bool os::Linux::release_memory_special_shm(char* base, size_t bytes) {
3635 // detaching the SHM segment will also delete it, see reserve_memory_special_shm()
3636 return shmdt(base) == 0;
3637 }
3638
3639 bool os::Linux::release_memory_special_huge_tlbfs(char* base, size_t bytes) {
3640 return pd_release_memory(base, bytes);
3641 }
3642
3643 bool os::release_memory_special(char* base, size_t bytes) {
3644 assert(UseLargePages, "only for large pages");
3645
3646 MemTracker::Tracker tkr = MemTracker::get_virtual_memory_release_tracker();
3647
3648 bool res;
3649 if (UseSHM) {
3650 res = os::Linux::release_memory_special_shm(base, bytes);
3651 } else {
3652 assert(UseHugeTLBFS, "must be");
3653 res = os::Linux::release_memory_special_huge_tlbfs(base, bytes);
3654 }
3655
3656 if (res) {
3657 tkr.record((address)base, bytes);
3658 } else {
3659 tkr.discard();
3660 }
3661
3662 return res;
3663 }
3664
3665 size_t os::large_page_size() {
3666 return _large_page_size;
3667 }
3668
3669 // With SysV SHM the entire memory region must be allocated as shared
3670 // memory.
3671 // HugeTLBFS allows application to commit large page memory on demand.
3672 // However, when committing memory with HugeTLBFS fails, the region
3673 // that was supposed to be committed will lose the old reservation
3674 // and allow other threads to steal that memory region. Because of this
3675 // behavior we can't commit HugeTLBFS memory.
3676 bool os::can_commit_large_page_memory() {
3677 return UseTransparentHugePages;
3678 }
3679
3680 bool os::can_execute_large_page_memory() {
3681 return UseTransparentHugePages || UseHugeTLBFS;
3682 }
3683
3684 // Reserve memory at an arbitrary address, only if that area is
3685 // available (and not reserved for something else).
3686
3687 char* os::pd_attempt_reserve_memory_at(size_t bytes, char* requested_addr) {
3688 const int max_tries = 10;
3689 char* base[max_tries];
3690 size_t size[max_tries];
3691 const size_t gap = 0x000000;
3692
3693 // Assert only that the size is a multiple of the page size, since
3694 // that's all that mmap requires, and since that's all we really know
3695 // about at this low abstraction level. If we need higher alignment,
3696 // we can either pass an alignment to this method or verify alignment
3697 // in one of the methods further up the call chain. See bug 5044738.
3698 assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block");
3699
3700 // Repeatedly allocate blocks until the block is allocated at the
3701 // right spot. Give up after max_tries. Note that reserve_memory() will
3702 // automatically update _highest_vm_reserved_address if the call is
3703 // successful. The variable tracks the highest memory address every reserved
3704 // by JVM. It is used to detect heap-stack collision if running with
3705 // fixed-stack LinuxThreads. Because here we may attempt to reserve more
3706 // space than needed, it could confuse the collision detecting code. To
3707 // solve the problem, save current _highest_vm_reserved_address and
3708 // calculate the correct value before return.
3709 address old_highest = _highest_vm_reserved_address;
3710
3711 // Linux mmap allows caller to pass an address as hint; give it a try first,
3712 // if kernel honors the hint then we can return immediately.
3713 char * addr = anon_mmap(requested_addr, bytes, false);
3714 if (addr == requested_addr) {
3715 return requested_addr;
3716 }
3717
3718 if (addr != NULL) {
3719 // mmap() is successful but it fails to reserve at the requested address
3720 anon_munmap(addr, bytes);
3721 }
3722
3723 int i;
3724 for (i = 0; i < max_tries; ++i) {
3725 base[i] = reserve_memory(bytes);
3726
3727 if (base[i] != NULL) {
3728 // Is this the block we wanted?
3729 if (base[i] == requested_addr) {
3730 size[i] = bytes;
3731 break;
3732 }
3733
3734 // Does this overlap the block we wanted? Give back the overlapped
3735 // parts and try again.
3736
3737 size_t top_overlap = requested_addr + (bytes + gap) - base[i];
3738 if (top_overlap >= 0 && top_overlap < bytes) {
3739 unmap_memory(base[i], top_overlap);
3740 base[i] += top_overlap;
3741 size[i] = bytes - top_overlap;
3742 } else {
3743 size_t bottom_overlap = base[i] + bytes - requested_addr;
3744 if (bottom_overlap >= 0 && bottom_overlap < bytes) {
3745 unmap_memory(requested_addr, bottom_overlap);
3746 size[i] = bytes - bottom_overlap;
3747 } else {
3748 size[i] = bytes;
3749 }
3750 }
3751 }
3752 }
3753
3754 // Give back the unused reserved pieces.
3755
3756 for (int j = 0; j < i; ++j) {
3757 if (base[j] != NULL) {
3758 unmap_memory(base[j], size[j]);
3759 }
3760 }
3761
3762 if (i < max_tries) {
3763 _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes);
3764 return requested_addr;
3765 } else {
3766 _highest_vm_reserved_address = old_highest;
3767 return NULL;
3768 }
3769 }
3770
3771 size_t os::read(int fd, void *buf, unsigned int nBytes) {
3772 return ::read(fd, buf, nBytes);
3773 }
3774
3775 //
3776 // Short sleep, direct OS call.
3777 //
3778 // Note: certain versions of Linux CFS scheduler (since 2.6.23) do not guarantee
3779 // sched_yield(2) will actually give up the CPU:
3780 //
3781 // * Alone on this pariticular CPU, keeps running.
3782 // * Before the introduction of "skip_buddy" with "compat_yield" disabled
3783 // (pre 2.6.39).
3784 //
3785 // So calling this with 0 is an alternative.
3786 //
3787 void os::naked_short_sleep(jlong ms) {
3788 struct timespec req;
3789
3790 assert(ms < 1000, "Un-interruptable sleep, short time use only");
3791 req.tv_sec = 0;
3792 if (ms > 0) {
3793 req.tv_nsec = (ms % 1000) * 1000000;
3794 }
3795 else {
3796 req.tv_nsec = 1;
3797 }
3798
3799 nanosleep(&req, NULL);
3800
3801 return;
3802 }
3803
3804 // Sleep forever; naked call to OS-specific sleep; use with CAUTION
3805 void os::infinite_sleep() {
3806 while (true) { // sleep forever ...
3807 ::sleep(100); // ... 100 seconds at a time
3808 }
3809 }
3810
3811 // Used to convert frequent JVM_Yield() to nops
3812 bool os::dont_yield() {
3813 return DontYieldALot;
3814 }
3815
3816 void os::yield() {
3817 sched_yield();
3818 }
3819
3820 os::YieldResult os::NakedYield() { sched_yield(); return os::YIELD_UNKNOWN ;}
3821
3822 void os::yield_all() {
3823 // Yields to all threads, including threads with lower priorities
3824 // Threads on Linux are all with same priority. The Solaris style
3825 // os::yield_all() with nanosleep(1ms) is not necessary.
3826 sched_yield();
3827 }
3828
3829 ////////////////////////////////////////////////////////////////////////////////
3830 // thread priority support
3831
3832 // Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER
3833 // only supports dynamic priority, static priority must be zero. For real-time
3834 // applications, Linux supports SCHED_RR which allows static priority (1-99).
3835 // However, for large multi-threaded applications, SCHED_RR is not only slower
3836 // than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out
3837 // of 5 runs - Sep 2005).
3838 //
3839 // The following code actually changes the niceness of kernel-thread/LWP. It
3840 // has an assumption that setpriority() only modifies one kernel-thread/LWP,
3841 // not the entire user process, and user level threads are 1:1 mapped to kernel
3842 // threads. It has always been the case, but could change in the future. For
3843 // this reason, the code should not be used as default (ThreadPriorityPolicy=0).
3844 // It is only used when ThreadPriorityPolicy=1 and requires root privilege.
3845
3846 int os::java_to_os_priority[CriticalPriority + 1] = {
3847 19, // 0 Entry should never be used
3848
3849 4, // 1 MinPriority
3850 3, // 2
3851 2, // 3
3852
3853 1, // 4
3854 0, // 5 NormPriority
3855 -1, // 6
3856
3857 -2, // 7
3858 -3, // 8
3859 -4, // 9 NearMaxPriority
3860
3861 -5, // 10 MaxPriority
3862
3863 -5 // 11 CriticalPriority
3864 };
3865
3866 static int prio_init() {
3867 if (ThreadPriorityPolicy == 1) {
3868 // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1
3869 // if effective uid is not root. Perhaps, a more elegant way of doing
3870 // this is to test CAP_SYS_NICE capability, but that will require libcap.so
3871 if (geteuid() != 0) {
3872 if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) {
3873 warning("-XX:ThreadPriorityPolicy requires root privilege on Linux");
3874 }
3875 ThreadPriorityPolicy = 0;
3876 }
3877 }
3878 if (UseCriticalJavaThreadPriority) {
3879 os::java_to_os_priority[MaxPriority] = os::java_to_os_priority[CriticalPriority];
3880 }
3881 return 0;
3882 }
3883
3884 OSReturn os::set_native_priority(Thread* thread, int newpri) {
3885 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) return OS_OK;
3886
3887 int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri);
3888 return (ret == 0) ? OS_OK : OS_ERR;
3889 }
3890
3891 OSReturn os::get_native_priority(const Thread* const thread, int *priority_ptr) {
3892 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) {
3893 *priority_ptr = java_to_os_priority[NormPriority];
3894 return OS_OK;
3895 }
3896
3897 errno = 0;
3898 *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id());
3899 return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR);
3900 }
3901
3902 // Hint to the underlying OS that a task switch would not be good.
3903 // Void return because it's a hint and can fail.
3904 void os::hint_no_preempt() {}
3905
3906 ////////////////////////////////////////////////////////////////////////////////
3907 // suspend/resume support
3908
3909 // the low-level signal-based suspend/resume support is a remnant from the
3910 // old VM-suspension that used to be for java-suspension, safepoints etc,
3911 // within hotspot. Now there is a single use-case for this:
3912 // - calling get_thread_pc() on the VMThread by the flat-profiler task
3913 // that runs in the watcher thread.
3914 // The remaining code is greatly simplified from the more general suspension
3915 // code that used to be used.
3916 //
3917 // The protocol is quite simple:
3918 // - suspend:
3919 // - sends a signal to the target thread
3920 // - polls the suspend state of the osthread using a yield loop
3921 // - target thread signal handler (SR_handler) sets suspend state
3922 // and blocks in sigsuspend until continued
3923 // - resume:
3924 // - sets target osthread state to continue
3925 // - sends signal to end the sigsuspend loop in the SR_handler
3926 //
3927 // Note that the SR_lock plays no role in this suspend/resume protocol.
3928 //
3929
3930 static void resume_clear_context(OSThread *osthread) {
3931 osthread->set_ucontext(NULL);
3932 osthread->set_siginfo(NULL);
3933 }
3934
3935 static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo, ucontext_t* context) {
3936 osthread->set_ucontext(context);
3937 osthread->set_siginfo(siginfo);
3938 }
3939
3940 //
3941 // Handler function invoked when a thread's execution is suspended or
3942 // resumed. We have to be careful that only async-safe functions are
3943 // called here (Note: most pthread functions are not async safe and
3944 // should be avoided.)
3945 //
3946 // Note: sigwait() is a more natural fit than sigsuspend() from an
3947 // interface point of view, but sigwait() prevents the signal hander
3948 // from being run. libpthread would get very confused by not having
3949 // its signal handlers run and prevents sigwait()'s use with the
3950 // mutex granting granting signal.
3951 //
3952 // Currently only ever called on the VMThread and JavaThreads (PC sampling)
3953 //
3954 static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) {
3955 // Save and restore errno to avoid confusing native code with EINTR
3956 // after sigsuspend.
3957 int old_errno = errno;
3958
3959 Thread* thread = Thread::current();
3960 OSThread* osthread = thread->osthread();
3961 assert(thread->is_VM_thread() || thread->is_Java_thread(), "Must be VMThread or JavaThread");
3962
3963 os::SuspendResume::State current = osthread->sr.state();
3964 if (current == os::SuspendResume::SR_SUSPEND_REQUEST) {
3965 suspend_save_context(osthread, siginfo, context);
3966
3967 // attempt to switch the state, we assume we had a SUSPEND_REQUEST
3968 os::SuspendResume::State state = osthread->sr.suspended();
3969 if (state == os::SuspendResume::SR_SUSPENDED) {
3970 sigset_t suspend_set; // signals for sigsuspend()
3971
3972 // get current set of blocked signals and unblock resume signal
3973 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set);
3974 sigdelset(&suspend_set, SR_signum);
3975
3976 sr_semaphore.signal();
3977 // wait here until we are resumed
3978 while (1) {
3979 sigsuspend(&suspend_set);
3980
3981 os::SuspendResume::State result = osthread->sr.running();
3982 if (result == os::SuspendResume::SR_RUNNING) {
3983 sr_semaphore.signal();
3984 break;
3985 }
3986 }
3987
3988 } else if (state == os::SuspendResume::SR_RUNNING) {
3989 // request was cancelled, continue
3990 } else {
3991 ShouldNotReachHere();
3992 }
3993
3994 resume_clear_context(osthread);
3995 } else if (current == os::SuspendResume::SR_RUNNING) {
3996 // request was cancelled, continue
3997 } else if (current == os::SuspendResume::SR_WAKEUP_REQUEST) {
3998 // ignore
3999 } else {
4000 // ignore
4001 }
4002
4003 errno = old_errno;
4004 }
4005
4006
4007 static int SR_initialize() {
4008 struct sigaction act;
4009 char *s;
4010 /* Get signal number to use for suspend/resume */
4011 if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) {
4012 int sig = ::strtol(s, 0, 10);
4013 if (sig > 0 || sig < _NSIG) {
4014 SR_signum = sig;
4015 }
4016 }
4017
4018 assert(SR_signum > SIGSEGV && SR_signum > SIGBUS,
4019 "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769");
4020
4021 sigemptyset(&SR_sigset);
4022 sigaddset(&SR_sigset, SR_signum);
4023
4024 /* Set up signal handler for suspend/resume */
4025 act.sa_flags = SA_RESTART|SA_SIGINFO;
4026 act.sa_handler = (void (*)(int)) SR_handler;
4027
4028 // SR_signum is blocked by default.
4029 // 4528190 - We also need to block pthread restart signal (32 on all
4030 // supported Linux platforms). Note that LinuxThreads need to block
4031 // this signal for all threads to work properly. So we don't have
4032 // to use hard-coded signal number when setting up the mask.
4033 pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask);
4034
4035 if (sigaction(SR_signum, &act, 0) == -1) {
4036 return -1;
4037 }
4038
4039 // Save signal flag
4040 os::Linux::set_our_sigflags(SR_signum, act.sa_flags);
4041 return 0;
4042 }
4043
4044 static int sr_notify(OSThread* osthread) {
4045 int status = pthread_kill(osthread->pthread_id(), SR_signum);
4046 assert_status(status == 0, status, "pthread_kill");
4047 return status;
4048 }
4049
4050 // "Randomly" selected value for how long we want to spin
4051 // before bailing out on suspending a thread, also how often
4052 // we send a signal to a thread we want to resume
4053 static const int RANDOMLY_LARGE_INTEGER = 1000000;
4054 static const int RANDOMLY_LARGE_INTEGER2 = 100;
4055
4056 // returns true on success and false on error - really an error is fatal
4057 // but this seems the normal response to library errors
4058 static bool do_suspend(OSThread* osthread) {
4059 assert(osthread->sr.is_running(), "thread should be running");
4060 assert(!sr_semaphore.trywait(), "semaphore has invalid state");
4061
4062 // mark as suspended and send signal
4063 if (osthread->sr.request_suspend() != os::SuspendResume::SR_SUSPEND_REQUEST) {
4064 // failed to switch, state wasn't running?
4065 ShouldNotReachHere();
4066 return false;
4067 }
4068
4069 if (sr_notify(osthread) != 0) {
4070 ShouldNotReachHere();
4071 }
4072
4073 // managed to send the signal and switch to SUSPEND_REQUEST, now wait for SUSPENDED
4074 while (true) {
4075 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) {
4076 break;
4077 } else {
4078 // timeout
4079 os::SuspendResume::State cancelled = osthread->sr.cancel_suspend();
4080 if (cancelled == os::SuspendResume::SR_RUNNING) {
4081 return false;
4082 } else if (cancelled == os::SuspendResume::SR_SUSPENDED) {
4083 // make sure that we consume the signal on the semaphore as well
4084 sr_semaphore.wait();
4085 break;
4086 } else {
4087 ShouldNotReachHere();
4088 return false;
4089 }
4090 }
4091 }
4092
4093 guarantee(osthread->sr.is_suspended(), "Must be suspended");
4094 return true;
4095 }
4096
4097 static void do_resume(OSThread* osthread) {
4098 assert(osthread->sr.is_suspended(), "thread should be suspended");
4099 assert(!sr_semaphore.trywait(), "invalid semaphore state");
4100
4101 if (osthread->sr.request_wakeup() != os::SuspendResume::SR_WAKEUP_REQUEST) {
4102 // failed to switch to WAKEUP_REQUEST
4103 ShouldNotReachHere();
4104 return;
4105 }
4106
4107 while (true) {
4108 if (sr_notify(osthread) == 0) {
4109 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) {
4110 if (osthread->sr.is_running()) {
4111 return;
4112 }
4113 }
4114 } else {
4115 ShouldNotReachHere();
4116 }
4117 }
4118
4119 guarantee(osthread->sr.is_running(), "Must be running!");
4120 }
4121
4122 ///////////////////////////////////////////////////////////////////////////////////
4123 // signal handling (except suspend/resume)
4124
4125 // This routine may be used by user applications as a "hook" to catch signals.
4126 // The user-defined signal handler must pass unrecognized signals to this
4127 // routine, and if it returns true (non-zero), then the signal handler must
4128 // return immediately. If the flag "abort_if_unrecognized" is true, then this
4129 // routine will never retun false (zero), but instead will execute a VM panic
4130 // routine kill the process.
4131 //
4132 // If this routine returns false, it is OK to call it again. This allows
4133 // the user-defined signal handler to perform checks either before or after
4134 // the VM performs its own checks. Naturally, the user code would be making
4135 // a serious error if it tried to handle an exception (such as a null check
4136 // or breakpoint) that the VM was generating for its own correct operation.
4137 //
4138 // This routine may recognize any of the following kinds of signals:
4139 // SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1.
4140 // It should be consulted by handlers for any of those signals.
4141 //
4142 // The caller of this routine must pass in the three arguments supplied
4143 // to the function referred to in the "sa_sigaction" (not the "sa_handler")
4144 // field of the structure passed to sigaction(). This routine assumes that
4145 // the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART.
4146 //
4147 // Note that the VM will print warnings if it detects conflicting signal
4148 // handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers".
4149 //
4150 extern "C" JNIEXPORT int
4151 JVM_handle_linux_signal(int signo, siginfo_t* siginfo,
4152 void* ucontext, int abort_if_unrecognized);
4153
4154 void signalHandler(int sig, siginfo_t* info, void* uc) {
4155 assert(info != NULL && uc != NULL, "it must be old kernel");
4156 int orig_errno = errno; // Preserve errno value over signal handler.
4157 JVM_handle_linux_signal(sig, info, uc, true);
4158 errno = orig_errno;
4159 }
4160
4161
4162 // This boolean allows users to forward their own non-matching signals
4163 // to JVM_handle_linux_signal, harmlessly.
4164 bool os::Linux::signal_handlers_are_installed = false;
4165
4166 // For signal-chaining
4167 struct sigaction os::Linux::sigact[MAXSIGNUM];
4168 unsigned int os::Linux::sigs = 0;
4169 bool os::Linux::libjsig_is_loaded = false;
4170 typedef struct sigaction *(*get_signal_t)(int);
4171 get_signal_t os::Linux::get_signal_action = NULL;
4172
4173 struct sigaction* os::Linux::get_chained_signal_action(int sig) {
4174 struct sigaction *actp = NULL;
4175
4176 if (libjsig_is_loaded) {
4177 // Retrieve the old signal handler from libjsig
4178 actp = (*get_signal_action)(sig);
4179 }
4180 if (actp == NULL) {
4181 // Retrieve the preinstalled signal handler from jvm
4182 actp = get_preinstalled_handler(sig);
4183 }
4184
4185 return actp;
4186 }
4187
4188 static bool call_chained_handler(struct sigaction *actp, int sig,
4189 siginfo_t *siginfo, void *context) {
4190 // Call the old signal handler
4191 if (actp->sa_handler == SIG_DFL) {
4192 // It's more reasonable to let jvm treat it as an unexpected exception
4193 // instead of taking the default action.
4194 return false;
4195 } else if (actp->sa_handler != SIG_IGN) {
4196 if ((actp->sa_flags & SA_NODEFER) == 0) {
4197 // automaticlly block the signal
4198 sigaddset(&(actp->sa_mask), sig);
4199 }
4200
4201 sa_handler_t hand;
4202 sa_sigaction_t sa;
4203 bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0;
4204 // retrieve the chained handler
4205 if (siginfo_flag_set) {
4206 sa = actp->sa_sigaction;
4207 } else {
4208 hand = actp->sa_handler;
4209 }
4210
4211 if ((actp->sa_flags & SA_RESETHAND) != 0) {
4212 actp->sa_handler = SIG_DFL;
4213 }
4214
4215 // try to honor the signal mask
4216 sigset_t oset;
4217 pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset);
4218
4219 // call into the chained handler
4220 if (siginfo_flag_set) {
4221 (*sa)(sig, siginfo, context);
4222 } else {
4223 (*hand)(sig);
4224 }
4225
4226 // restore the signal mask
4227 pthread_sigmask(SIG_SETMASK, &oset, 0);
4228 }
4229 // Tell jvm's signal handler the signal is taken care of.
4230 return true;
4231 }
4232
4233 bool os::Linux::chained_handler(int sig, siginfo_t* siginfo, void* context) {
4234 bool chained = false;
4235 // signal-chaining
4236 if (UseSignalChaining) {
4237 struct sigaction *actp = get_chained_signal_action(sig);
4238 if (actp != NULL) {
4239 chained = call_chained_handler(actp, sig, siginfo, context);
4240 }
4241 }
4242 return chained;
4243 }
4244
4245 struct sigaction* os::Linux::get_preinstalled_handler(int sig) {
4246 if ((( (unsigned int)1 << sig ) & sigs) != 0) {
4247 return &sigact[sig];
4248 }
4249 return NULL;
4250 }
4251
4252 void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) {
4253 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4254 sigact[sig] = oldAct;
4255 sigs |= (unsigned int)1 << sig;
4256 }
4257
4258 // for diagnostic
4259 int os::Linux::sigflags[MAXSIGNUM];
4260
4261 int os::Linux::get_our_sigflags(int sig) {
4262 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4263 return sigflags[sig];
4264 }
4265
4266 void os::Linux::set_our_sigflags(int sig, int flags) {
4267 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4268 sigflags[sig] = flags;
4269 }
4270
4271 void os::Linux::set_signal_handler(int sig, bool set_installed) {
4272 // Check for overwrite.
4273 struct sigaction oldAct;
4274 sigaction(sig, (struct sigaction*)NULL, &oldAct);
4275
4276 void* oldhand = oldAct.sa_sigaction
4277 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction)
4278 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler);
4279 if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) &&
4280 oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) &&
4281 oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) {
4282 if (AllowUserSignalHandlers || !set_installed) {
4283 // Do not overwrite; user takes responsibility to forward to us.
4284 return;
4285 } else if (UseSignalChaining) {
4286 // save the old handler in jvm
4287 save_preinstalled_handler(sig, oldAct);
4288 // libjsig also interposes the sigaction() call below and saves the
4289 // old sigaction on it own.
4290 } else {
4291 fatal(err_msg("Encountered unexpected pre-existing sigaction handler "
4292 "%#lx for signal %d.", (long)oldhand, sig));
4293 }
4294 }
4295
4296 struct sigaction sigAct;
4297 sigfillset(&(sigAct.sa_mask));
4298 sigAct.sa_handler = SIG_DFL;
4299 if (!set_installed) {
4300 sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
4301 } else {
4302 sigAct.sa_sigaction = signalHandler;
4303 sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
4304 }
4305 // Save flags, which are set by ours
4306 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4307 sigflags[sig] = sigAct.sa_flags;
4308
4309 int ret = sigaction(sig, &sigAct, &oldAct);
4310 assert(ret == 0, "check");
4311
4312 void* oldhand2 = oldAct.sa_sigaction
4313 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction)
4314 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler);
4315 assert(oldhand2 == oldhand, "no concurrent signal handler installation");
4316 }
4317
4318 // install signal handlers for signals that HotSpot needs to
4319 // handle in order to support Java-level exception handling.
4320
4321 void os::Linux::install_signal_handlers() {
4322 if (!signal_handlers_are_installed) {
4323 signal_handlers_are_installed = true;
4324
4325 // signal-chaining
4326 typedef void (*signal_setting_t)();
4327 signal_setting_t begin_signal_setting = NULL;
4328 signal_setting_t end_signal_setting = NULL;
4329 begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
4330 dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting"));
4331 if (begin_signal_setting != NULL) {
4332 end_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
4333 dlsym(RTLD_DEFAULT, "JVM_end_signal_setting"));
4334 get_signal_action = CAST_TO_FN_PTR(get_signal_t,
4335 dlsym(RTLD_DEFAULT, "JVM_get_signal_action"));
4336 libjsig_is_loaded = true;
4337 assert(UseSignalChaining, "should enable signal-chaining");
4338 }
4339 if (libjsig_is_loaded) {
4340 // Tell libjsig jvm is setting signal handlers
4341 (*begin_signal_setting)();
4342 }
4343
4344 set_signal_handler(SIGSEGV, true);
4345 set_signal_handler(SIGPIPE, true);
4346 set_signal_handler(SIGBUS, true);
4347 set_signal_handler(SIGILL, true);
4348 set_signal_handler(SIGFPE, true);
4349 #if defined(PPC64)
4350 set_signal_handler(SIGTRAP, true);
4351 #endif
4352 set_signal_handler(SIGXFSZ, true);
4353
4354 if (libjsig_is_loaded) {
4355 // Tell libjsig jvm finishes setting signal handlers
4356 (*end_signal_setting)();
4357 }
4358
4359 // We don't activate signal checker if libjsig is in place, we trust ourselves
4360 // and if UserSignalHandler is installed all bets are off.
4361 // Log that signal checking is off only if -verbose:jni is specified.
4362 if (CheckJNICalls) {
4363 if (libjsig_is_loaded) {
4364 if (PrintJNIResolving) {
4365 tty->print_cr("Info: libjsig is activated, all active signal checking is disabled");
4366 }
4367 check_signals = false;
4368 }
4369 if (AllowUserSignalHandlers) {
4370 if (PrintJNIResolving) {
4371 tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled");
4372 }
4373 check_signals = false;
4374 }
4375 }
4376 }
4377 }
4378
4379 // This is the fastest way to get thread cpu time on Linux.
4380 // Returns cpu time (user+sys) for any thread, not only for current.
4381 // POSIX compliant clocks are implemented in the kernels 2.6.16+.
4382 // It might work on 2.6.10+ with a special kernel/glibc patch.
4383 // For reference, please, see IEEE Std 1003.1-2004:
4384 // http://www.unix.org/single_unix_specification
4385
4386 jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) {
4387 struct timespec tp;
4388 int rc = os::Linux::clock_gettime(clockid, &tp);
4389 assert(rc == 0, "clock_gettime is expected to return 0 code");
4390
4391 return (tp.tv_sec * NANOSECS_PER_SEC) + tp.tv_nsec;
4392 }
4393
4394 /////
4395 // glibc on Linux platform uses non-documented flag
4396 // to indicate, that some special sort of signal
4397 // trampoline is used.
4398 // We will never set this flag, and we should
4399 // ignore this flag in our diagnostic
4400 #ifdef SIGNIFICANT_SIGNAL_MASK
4401 #undef SIGNIFICANT_SIGNAL_MASK
4402 #endif
4403 #define SIGNIFICANT_SIGNAL_MASK (~0x04000000)
4404
4405 static const char* get_signal_handler_name(address handler,
4406 char* buf, int buflen) {
4407 int offset;
4408 bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset);
4409 if (found) {
4410 // skip directory names
4411 const char *p1, *p2;
4412 p1 = buf;
4413 size_t len = strlen(os::file_separator());
4414 while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len;
4415 jio_snprintf(buf, buflen, "%s+0x%x", p1, offset);
4416 } else {
4417 jio_snprintf(buf, buflen, PTR_FORMAT, handler);
4418 }
4419 return buf;
4420 }
4421
4422 static void print_signal_handler(outputStream* st, int sig,
4423 char* buf, size_t buflen) {
4424 struct sigaction sa;
4425
4426 sigaction(sig, NULL, &sa);
4427
4428 // See comment for SIGNIFICANT_SIGNAL_MASK define
4429 sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
4430
4431 st->print("%s: ", os::exception_name(sig, buf, buflen));
4432
4433 address handler = (sa.sa_flags & SA_SIGINFO)
4434 ? CAST_FROM_FN_PTR(address, sa.sa_sigaction)
4435 : CAST_FROM_FN_PTR(address, sa.sa_handler);
4436
4437 if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) {
4438 st->print("SIG_DFL");
4439 } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) {
4440 st->print("SIG_IGN");
4441 } else {
4442 st->print("[%s]", get_signal_handler_name(handler, buf, buflen));
4443 }
4444
4445 st->print(", sa_mask[0]=");
4446 os::Posix::print_signal_set_short(st, &sa.sa_mask);
4447
4448 address rh = VMError::get_resetted_sighandler(sig);
4449 // May be, handler was resetted by VMError?
4450 if(rh != NULL) {
4451 handler = rh;
4452 sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK;
4453 }
4454
4455 st->print(", sa_flags=");
4456 os::Posix::print_sa_flags(st, sa.sa_flags);
4457
4458 // Check: is it our handler?
4459 if(handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) ||
4460 handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) {
4461 // It is our signal handler
4462 // check for flags, reset system-used one!
4463 if((int)sa.sa_flags != os::Linux::get_our_sigflags(sig)) {
4464 st->print(
4465 ", flags was changed from " PTR32_FORMAT ", consider using jsig library",
4466 os::Linux::get_our_sigflags(sig));
4467 }
4468 }
4469 st->cr();
4470 }
4471
4472
4473 #define DO_SIGNAL_CHECK(sig) \
4474 if (!sigismember(&check_signal_done, sig)) \
4475 os::Linux::check_signal_handler(sig)
4476
4477 // This method is a periodic task to check for misbehaving JNI applications
4478 // under CheckJNI, we can add any periodic checks here
4479
4480 void os::run_periodic_checks() {
4481
4482 if (check_signals == false) return;
4483
4484 // SEGV and BUS if overridden could potentially prevent
4485 // generation of hs*.log in the event of a crash, debugging
4486 // such a case can be very challenging, so we absolutely
4487 // check the following for a good measure:
4488 DO_SIGNAL_CHECK(SIGSEGV);
4489 DO_SIGNAL_CHECK(SIGILL);
4490 DO_SIGNAL_CHECK(SIGFPE);
4491 DO_SIGNAL_CHECK(SIGBUS);
4492 DO_SIGNAL_CHECK(SIGPIPE);
4493 DO_SIGNAL_CHECK(SIGXFSZ);
4494 #if defined(PPC64)
4495 DO_SIGNAL_CHECK(SIGTRAP);
4496 #endif
4497
4498 // ReduceSignalUsage allows the user to override these handlers
4499 // see comments at the very top and jvm_solaris.h
4500 if (!ReduceSignalUsage) {
4501 DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL);
4502 DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL);
4503 DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL);
4504 DO_SIGNAL_CHECK(BREAK_SIGNAL);
4505 }
4506
4507 DO_SIGNAL_CHECK(SR_signum);
4508 DO_SIGNAL_CHECK(INTERRUPT_SIGNAL);
4509 }
4510
4511 typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *);
4512
4513 static os_sigaction_t os_sigaction = NULL;
4514
4515 void os::Linux::check_signal_handler(int sig) {
4516 char buf[O_BUFLEN];
4517 address jvmHandler = NULL;
4518
4519
4520 struct sigaction act;
4521 if (os_sigaction == NULL) {
4522 // only trust the default sigaction, in case it has been interposed
4523 os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction");
4524 if (os_sigaction == NULL) return;
4525 }
4526
4527 os_sigaction(sig, (struct sigaction*)NULL, &act);
4528
4529
4530 act.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
4531
4532 address thisHandler = (act.sa_flags & SA_SIGINFO)
4533 ? CAST_FROM_FN_PTR(address, act.sa_sigaction)
4534 : CAST_FROM_FN_PTR(address, act.sa_handler) ;
4535
4536
4537 switch(sig) {
4538 case SIGSEGV:
4539 case SIGBUS:
4540 case SIGFPE:
4541 case SIGPIPE:
4542 case SIGILL:
4543 case SIGXFSZ:
4544 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler);
4545 break;
4546
4547 case SHUTDOWN1_SIGNAL:
4548 case SHUTDOWN2_SIGNAL:
4549 case SHUTDOWN3_SIGNAL:
4550 case BREAK_SIGNAL:
4551 jvmHandler = (address)user_handler();
4552 break;
4553
4554 case INTERRUPT_SIGNAL:
4555 jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL);
4556 break;
4557
4558 default:
4559 if (sig == SR_signum) {
4560 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler);
4561 } else {
4562 return;
4563 }
4564 break;
4565 }
4566
4567 if (thisHandler != jvmHandler) {
4568 tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN));
4569 tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN));
4570 tty->print_cr(" found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN));
4571 // No need to check this sig any longer
4572 sigaddset(&check_signal_done, sig);
4573 // Running under non-interactive shell, SHUTDOWN2_SIGNAL will be reassigned SIG_IGN
4574 if (sig == SHUTDOWN2_SIGNAL && !isatty(fileno(stdin))) {
4575 tty->print_cr("Running in non-interactive shell, %s handler is replaced by shell",
4576 exception_name(sig, buf, O_BUFLEN));
4577 }
4578 } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) {
4579 tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN));
4580 tty->print("expected:" PTR32_FORMAT, os::Linux::get_our_sigflags(sig));
4581 tty->print_cr(" found:" PTR32_FORMAT, act.sa_flags);
4582 // No need to check this sig any longer
4583 sigaddset(&check_signal_done, sig);
4584 }
4585
4586 // Dump all the signal
4587 if (sigismember(&check_signal_done, sig)) {
4588 print_signal_handlers(tty, buf, O_BUFLEN);
4589 }
4590 }
4591
4592 extern void report_error(char* file_name, int line_no, char* title, char* format, ...);
4593
4594 extern bool signal_name(int signo, char* buf, size_t len);
4595
4596 const char* os::exception_name(int exception_code, char* buf, size_t size) {
4597 if (0 < exception_code && exception_code <= SIGRTMAX) {
4598 // signal
4599 if (!signal_name(exception_code, buf, size)) {
4600 jio_snprintf(buf, size, "SIG%d", exception_code);
4601 }
4602 return buf;
4603 } else {
4604 return NULL;
4605 }
4606 }
4607
4608 // this is called _before_ the most of global arguments have been parsed
4609 void os::init(void) {
4610 char dummy; /* used to get a guess on initial stack address */
4611 // first_hrtime = gethrtime();
4612
4613 // With LinuxThreads the JavaMain thread pid (primordial thread)
4614 // is different than the pid of the java launcher thread.
4615 // So, on Linux, the launcher thread pid is passed to the VM
4616 // via the sun.java.launcher.pid property.
4617 // Use this property instead of getpid() if it was correctly passed.
4618 // See bug 6351349.
4619 pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid();
4620
4621 _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid();
4622
4623 clock_tics_per_sec = sysconf(_SC_CLK_TCK);
4624
4625 init_random(1234567);
4626
4627 ThreadCritical::initialize();
4628
4629 Linux::set_page_size(sysconf(_SC_PAGESIZE));
4630 if (Linux::page_size() == -1) {
4631 fatal(err_msg("os_linux.cpp: os::init: sysconf failed (%s)",
4632 strerror(errno)));
4633 }
4634 init_page_sizes((size_t) Linux::page_size());
4635
4636 Linux::initialize_system_info();
4637
4638 // main_thread points to the aboriginal thread
4639 Linux::_main_thread = pthread_self();
4640
4641 Linux::clock_init();
4642 initial_time_count = javaTimeNanos();
4643
4644 // pthread_condattr initialization for monotonic clock
4645 int status;
4646 pthread_condattr_t* _condattr = os::Linux::condAttr();
4647 if ((status = pthread_condattr_init(_condattr)) != 0) {
4648 fatal(err_msg("pthread_condattr_init: %s", strerror(status)));
4649 }
4650 // Only set the clock if CLOCK_MONOTONIC is available
4651 if (os::supports_monotonic_clock()) {
4652 if ((status = pthread_condattr_setclock(_condattr, CLOCK_MONOTONIC)) != 0) {
4653 if (status == EINVAL) {
4654 warning("Unable to use monotonic clock with relative timed-waits" \
4655 " - changes to the time-of-day clock may have adverse affects");
4656 } else {
4657 fatal(err_msg("pthread_condattr_setclock: %s", strerror(status)));
4658 }
4659 }
4660 }
4661 // else it defaults to CLOCK_REALTIME
4662
4663 pthread_mutex_init(&dl_mutex, NULL);
4664
4665 // If the pagesize of the VM is greater than 8K determine the appropriate
4666 // number of initial guard pages. The user can change this with the
4667 // command line arguments, if needed.
4668 if (vm_page_size() > (int)Linux::vm_default_page_size()) {
4669 StackYellowPages = 1;
4670 StackRedPages = 1;
4671 StackShadowPages = round_to((StackShadowPages*Linux::vm_default_page_size()), vm_page_size()) / vm_page_size();
4672 }
4673 }
4674
4675 // To install functions for atexit system call
4676 extern "C" {
4677 static void perfMemory_exit_helper() {
4678 perfMemory_exit();
4679 }
4680 }
4681
4682 // this is called _after_ the global arguments have been parsed
4683 jint os::init_2(void)
4684 {
4685 Linux::fast_thread_clock_init();
4686
4687 // Allocate a single page and mark it as readable for safepoint polling
4688 address polling_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
4689 guarantee( polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page" );
4690
4691 os::set_polling_page( polling_page );
4692
4693 #ifndef PRODUCT
4694 if(Verbose && PrintMiscellaneous)
4695 tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n", (intptr_t)polling_page);
4696 #endif
4697
4698 if (!UseMembar) {
4699 address mem_serialize_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
4700 guarantee( mem_serialize_page != MAP_FAILED, "mmap Failed for memory serialize page");
4701 os::set_memory_serialize_page( mem_serialize_page );
4702
4703 #ifndef PRODUCT
4704 if(Verbose && PrintMiscellaneous)
4705 tty->print("[Memory Serialize Page address: " INTPTR_FORMAT "]\n", (intptr_t)mem_serialize_page);
4706 #endif
4707 }
4708
4709 // initialize suspend/resume support - must do this before signal_sets_init()
4710 if (SR_initialize() != 0) {
4711 perror("SR_initialize failed");
4712 return JNI_ERR;
4713 }
4714
4715 Linux::signal_sets_init();
4716 Linux::install_signal_handlers();
4717
4718 // Check minimum allowable stack size for thread creation and to initialize
4719 // the java system classes, including StackOverflowError - depends on page
4720 // size. Add a page for compiler2 recursion in main thread.
4721 // Add in 2*BytesPerWord times page size to account for VM stack during
4722 // class initialization depending on 32 or 64 bit VM.
4723 os::Linux::min_stack_allowed = MAX2(os::Linux::min_stack_allowed,
4724 (size_t)(StackYellowPages+StackRedPages+StackShadowPages) * Linux::page_size() +
4725 (2*BytesPerWord COMPILER2_PRESENT(+1)) * Linux::vm_default_page_size());
4726
4727 size_t threadStackSizeInBytes = ThreadStackSize * K;
4728 if (threadStackSizeInBytes != 0 &&
4729 threadStackSizeInBytes < os::Linux::min_stack_allowed) {
4730 tty->print_cr("\nThe stack size specified is too small, "
4731 "Specify at least %dk",
4732 os::Linux::min_stack_allowed/ K);
4733 return JNI_ERR;
4734 }
4735
4736 // Make the stack size a multiple of the page size so that
4737 // the yellow/red zones can be guarded.
4738 JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes,
4739 vm_page_size()));
4740
4741 Linux::capture_initial_stack(JavaThread::stack_size_at_create());
4742
4743 #if defined(IA32)
4744 workaround_expand_exec_shield_cs_limit();
4745 #endif
4746
4747 Linux::libpthread_init();
4748 if (PrintMiscellaneous && (Verbose || WizardMode)) {
4749 tty->print_cr("[HotSpot is running with %s, %s(%s)]\n",
4750 Linux::glibc_version(), Linux::libpthread_version(),
4751 Linux::is_floating_stack() ? "floating stack" : "fixed stack");
4752 }
4753
4754 if (UseNUMA) {
4755 if (!Linux::libnuma_init()) {
4756 UseNUMA = false;
4757 } else {
4758 if ((Linux::numa_max_node() < 1)) {
4759 // There's only one node(they start from 0), disable NUMA.
4760 UseNUMA = false;
4761 }
4762 }
4763 // With SHM and HugeTLBFS large pages we cannot uncommit a page, so there's no way
4764 // we can make the adaptive lgrp chunk resizing work. If the user specified
4765 // both UseNUMA and UseLargePages (or UseSHM/UseHugeTLBFS) on the command line - warn and
4766 // disable adaptive resizing.
4767 if (UseNUMA && UseLargePages && !can_commit_large_page_memory()) {
4768 if (FLAG_IS_DEFAULT(UseNUMA)) {
4769 UseNUMA = false;
4770 } else {
4771 if (FLAG_IS_DEFAULT(UseLargePages) &&
4772 FLAG_IS_DEFAULT(UseSHM) &&
4773 FLAG_IS_DEFAULT(UseHugeTLBFS)) {
4774 UseLargePages = false;
4775 } else {
4776 warning("UseNUMA is not fully compatible with SHM/HugeTLBFS large pages, disabling adaptive resizing");
4777 UseAdaptiveSizePolicy = false;
4778 UseAdaptiveNUMAChunkSizing = false;
4779 }
4780 }
4781 }
4782 if (!UseNUMA && ForceNUMA) {
4783 UseNUMA = true;
4784 }
4785 }
4786
4787 if (MaxFDLimit) {
4788 // set the number of file descriptors to max. print out error
4789 // if getrlimit/setrlimit fails but continue regardless.
4790 struct rlimit nbr_files;
4791 int status = getrlimit(RLIMIT_NOFILE, &nbr_files);
4792 if (status != 0) {
4793 if (PrintMiscellaneous && (Verbose || WizardMode))
4794 perror("os::init_2 getrlimit failed");
4795 } else {
4796 nbr_files.rlim_cur = nbr_files.rlim_max;
4797 status = setrlimit(RLIMIT_NOFILE, &nbr_files);
4798 if (status != 0) {
4799 if (PrintMiscellaneous && (Verbose || WizardMode))
4800 perror("os::init_2 setrlimit failed");
4801 }
4802 }
4803 }
4804
4805 // Initialize lock used to serialize thread creation (see os::create_thread)
4806 Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false));
4807
4808 // at-exit methods are called in the reverse order of their registration.
4809 // atexit functions are called on return from main or as a result of a
4810 // call to exit(3C). There can be only 32 of these functions registered
4811 // and atexit() does not set errno.
4812
4813 if (PerfAllowAtExitRegistration) {
4814 // only register atexit functions if PerfAllowAtExitRegistration is set.
4815 // atexit functions can be delayed until process exit time, which
4816 // can be problematic for embedded VM situations. Embedded VMs should
4817 // call DestroyJavaVM() to assure that VM resources are released.
4818
4819 // note: perfMemory_exit_helper atexit function may be removed in
4820 // the future if the appropriate cleanup code can be added to the
4821 // VM_Exit VMOperation's doit method.
4822 if (atexit(perfMemory_exit_helper) != 0) {
4823 warning("os::init_2 atexit(perfMemory_exit_helper) failed");
4824 }
4825 }
4826
4827 // initialize thread priority policy
4828 prio_init();
4829
4830 return JNI_OK;
4831 }
4832
4833 // this is called at the end of vm_initialization
4834 void os::init_3(void) {
4835 #ifdef JAVASE_EMBEDDED
4836 // Start the MemNotifyThread
4837 if (LowMemoryProtection) {
4838 MemNotifyThread::start();
4839 }
4840 return;
4841 #endif
4842 }
4843
4844 // Mark the polling page as unreadable
4845 void os::make_polling_page_unreadable(void) {
4846 if( !guard_memory((char*)_polling_page, Linux::page_size()) )
4847 fatal("Could not disable polling page");
4848 };
4849
4850 // Mark the polling page as readable
4851 void os::make_polling_page_readable(void) {
4852 if( !linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) {
4853 fatal("Could not enable polling page");
4854 }
4855 };
4856
4857 int os::active_processor_count() {
4858 // Linux doesn't yet have a (official) notion of processor sets,
4859 // so just return the number of online processors.
4860 int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN);
4861 assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check");
4862 return online_cpus;
4863 }
4864
4865 void os::set_native_thread_name(const char *name) {
4866 // Not yet implemented.
4867 return;
4868 }
4869
4870 bool os::distribute_processes(uint length, uint* distribution) {
4871 // Not yet implemented.
4872 return false;
4873 }
4874
4875 bool os::bind_to_processor(uint processor_id) {
4876 // Not yet implemented.
4877 return false;
4878 }
4879
4880 ///
4881
4882 void os::SuspendedThreadTask::internal_do_task() {
4883 if (do_suspend(_thread->osthread())) {
4884 SuspendedThreadTaskContext context(_thread, _thread->osthread()->ucontext());
4885 do_task(context);
4886 do_resume(_thread->osthread());
4887 }
4888 }
4889
4890 class PcFetcher : public os::SuspendedThreadTask {
4891 public:
4892 PcFetcher(Thread* thread) : os::SuspendedThreadTask(thread) {}
4893 ExtendedPC result();
4894 protected:
4895 void do_task(const os::SuspendedThreadTaskContext& context);
4896 private:
4897 ExtendedPC _epc;
4898 };
4899
4900 ExtendedPC PcFetcher::result() {
4901 guarantee(is_done(), "task is not done yet.");
4902 return _epc;
4903 }
4904
4905 void PcFetcher::do_task(const os::SuspendedThreadTaskContext& context) {
4906 Thread* thread = context.thread();
4907 OSThread* osthread = thread->osthread();
4908 if (osthread->ucontext() != NULL) {
4909 _epc = os::Linux::ucontext_get_pc((ucontext_t *) context.ucontext());
4910 } else {
4911 // NULL context is unexpected, double-check this is the VMThread
4912 guarantee(thread->is_VM_thread(), "can only be called for VMThread");
4913 }
4914 }
4915
4916 // Suspends the target using the signal mechanism and then grabs the PC before
4917 // resuming the target. Used by the flat-profiler only
4918 ExtendedPC os::get_thread_pc(Thread* thread) {
4919 // Make sure that it is called by the watcher for the VMThread
4920 assert(Thread::current()->is_Watcher_thread(), "Must be watcher");
4921 assert(thread->is_VM_thread(), "Can only be called for VMThread");
4922
4923 PcFetcher fetcher(thread);
4924 fetcher.run();
4925 return fetcher.result();
4926 }
4927
4928 int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond, pthread_mutex_t *_mutex, const struct timespec *_abstime)
4929 {
4930 if (is_NPTL()) {
4931 return pthread_cond_timedwait(_cond, _mutex, _abstime);
4932 } else {
4933 // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control
4934 // word back to default 64bit precision if condvar is signaled. Java
4935 // wants 53bit precision. Save and restore current value.
4936 int fpu = get_fpu_control_word();
4937 int status = pthread_cond_timedwait(_cond, _mutex, _abstime);
4938 set_fpu_control_word(fpu);
4939 return status;
4940 }
4941 }
4942
4943 ////////////////////////////////////////////////////////////////////////////////
4944 // debug support
4945
4946 bool os::find(address addr, outputStream* st) {
4947 Dl_info dlinfo;
4948 memset(&dlinfo, 0, sizeof(dlinfo));
4949 if (dladdr(addr, &dlinfo) != 0) {
4950 st->print(PTR_FORMAT ": ", addr);
4951 if (dlinfo.dli_sname != NULL && dlinfo.dli_saddr != NULL) {
4952 st->print("%s+%#x", dlinfo.dli_sname,
4953 addr - (intptr_t)dlinfo.dli_saddr);
4954 } else if (dlinfo.dli_fbase != NULL) {
4955 st->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase);
4956 } else {
4957 st->print("<absolute address>");
4958 }
4959 if (dlinfo.dli_fname != NULL) {
4960 st->print(" in %s", dlinfo.dli_fname);
4961 }
4962 if (dlinfo.dli_fbase != NULL) {
4963 st->print(" at " PTR_FORMAT, dlinfo.dli_fbase);
4964 }
4965 st->cr();
4966
4967 if (Verbose) {
4968 // decode some bytes around the PC
4969 address begin = clamp_address_in_page(addr-40, addr, os::vm_page_size());
4970 address end = clamp_address_in_page(addr+40, addr, os::vm_page_size());
4971 address lowest = (address) dlinfo.dli_sname;
4972 if (!lowest) lowest = (address) dlinfo.dli_fbase;
4973 if (begin < lowest) begin = lowest;
4974 Dl_info dlinfo2;
4975 if (dladdr(end, &dlinfo2) != 0 && dlinfo2.dli_saddr != dlinfo.dli_saddr
4976 && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin)
4977 end = (address) dlinfo2.dli_saddr;
4978 Disassembler::decode(begin, end, st);
4979 }
4980 return true;
4981 }
4982 return false;
4983 }
4984
4985 ////////////////////////////////////////////////////////////////////////////////
4986 // misc
4987
4988 // This does not do anything on Linux. This is basically a hook for being
4989 // able to use structured exception handling (thread-local exception filters)
4990 // on, e.g., Win32.
4991 void
4992 os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method,
4993 JavaCallArguments* args, Thread* thread) {
4994 f(value, method, args, thread);
4995 }
4996
4997 void os::print_statistics() {
4998 }
4999
5000 int os::message_box(const char* title, const char* message) {
5001 int i;
5002 fdStream err(defaultStream::error_fd());
5003 for (i = 0; i < 78; i++) err.print_raw("=");
5004 err.cr();
5005 err.print_raw_cr(title);
5006 for (i = 0; i < 78; i++) err.print_raw("-");
5007 err.cr();
5008 err.print_raw_cr(message);
5009 for (i = 0; i < 78; i++) err.print_raw("=");
5010 err.cr();
5011
5012 char buf[16];
5013 // Prevent process from exiting upon "read error" without consuming all CPU
5014 while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); }
5015
5016 return buf[0] == 'y' || buf[0] == 'Y';
5017 }
5018
5019 int os::stat(const char *path, struct stat *sbuf) {
5020 char pathbuf[MAX_PATH];
5021 if (strlen(path) > MAX_PATH - 1) {
5022 errno = ENAMETOOLONG;
5023 return -1;
5024 }
5025 os::native_path(strcpy(pathbuf, path));
5026 return ::stat(pathbuf, sbuf);
5027 }
5028
5029 bool os::check_heap(bool force) {
5030 return true;
5031 }
5032
5033 int local_vsnprintf(char* buf, size_t count, const char* format, va_list args) {
5034 return ::vsnprintf(buf, count, format, args);
5035 }
5036
5037 // Is a (classpath) directory empty?
5038 bool os::dir_is_empty(const char* path) {
5039 DIR *dir = NULL;
5040 struct dirent *ptr;
5041
5042 dir = opendir(path);
5043 if (dir == NULL) return true;
5044
5045 /* Scan the directory */
5046 bool result = true;
5047 char buf[sizeof(struct dirent) + MAX_PATH];
5048 while (result && (ptr = ::readdir(dir)) != NULL) {
5049 if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) {
5050 result = false;
5051 }
5052 }
5053 closedir(dir);
5054 return result;
5055 }
5056
5057 // This code originates from JDK's sysOpen and open64_w
5058 // from src/solaris/hpi/src/system_md.c
5059
5060 #ifndef O_DELETE
5061 #define O_DELETE 0x10000
5062 #endif
5063
5064 // Open a file. Unlink the file immediately after open returns
5065 // if the specified oflag has the O_DELETE flag set.
5066 // O_DELETE is used only in j2se/src/share/native/java/util/zip/ZipFile.c
5067
5068 int os::open(const char *path, int oflag, int mode) {
5069
5070 if (strlen(path) > MAX_PATH - 1) {
5071 errno = ENAMETOOLONG;
5072 return -1;
5073 }
5074 int fd;
5075 int o_delete = (oflag & O_DELETE);
5076 oflag = oflag & ~O_DELETE;
5077
5078 fd = ::open64(path, oflag, mode);
5079 if (fd == -1) return -1;
5080
5081 //If the open succeeded, the file might still be a directory
5082 {
5083 struct stat64 buf64;
5084 int ret = ::fstat64(fd, &buf64);
5085 int st_mode = buf64.st_mode;
5086
5087 if (ret != -1) {
5088 if ((st_mode & S_IFMT) == S_IFDIR) {
5089 errno = EISDIR;
5090 ::close(fd);
5091 return -1;
5092 }
5093 } else {
5094 ::close(fd);
5095 return -1;
5096 }
5097 }
5098
5099 /*
5100 * All file descriptors that are opened in the JVM and not
5101 * specifically destined for a subprocess should have the
5102 * close-on-exec flag set. If we don't set it, then careless 3rd
5103 * party native code might fork and exec without closing all
5104 * appropriate file descriptors (e.g. as we do in closeDescriptors in
5105 * UNIXProcess.c), and this in turn might:
5106 *
5107 * - cause end-of-file to fail to be detected on some file
5108 * descriptors, resulting in mysterious hangs, or
5109 *
5110 * - might cause an fopen in the subprocess to fail on a system
5111 * suffering from bug 1085341.
5112 *
5113 * (Yes, the default setting of the close-on-exec flag is a Unix
5114 * design flaw)
5115 *
5116 * See:
5117 * 1085341: 32-bit stdio routines should support file descriptors >255
5118 * 4843136: (process) pipe file descriptor from Runtime.exec not being closed
5119 * 6339493: (process) Runtime.exec does not close all file descriptors on Solaris 9
5120 */
5121 #ifdef FD_CLOEXEC
5122 {
5123 int flags = ::fcntl(fd, F_GETFD);
5124 if (flags != -1)
5125 ::fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
5126 }
5127 #endif
5128
5129 if (o_delete != 0) {
5130 ::unlink(path);
5131 }
5132 return fd;
5133 }
5134
5135
5136 // create binary file, rewriting existing file if required
5137 int os::create_binary_file(const char* path, bool rewrite_existing) {
5138 int oflags = O_WRONLY | O_CREAT;
5139 if (!rewrite_existing) {
5140 oflags |= O_EXCL;
5141 }
5142 return ::open64(path, oflags, S_IREAD | S_IWRITE);
5143 }
5144
5145 // return current position of file pointer
5146 jlong os::current_file_offset(int fd) {
5147 return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR);
5148 }
5149
5150 // move file pointer to the specified offset
5151 jlong os::seek_to_file_offset(int fd, jlong offset) {
5152 return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET);
5153 }
5154
5155 // This code originates from JDK's sysAvailable
5156 // from src/solaris/hpi/src/native_threads/src/sys_api_td.c
5157
5158 int os::available(int fd, jlong *bytes) {
5159 jlong cur, end;
5160 int mode;
5161 struct stat64 buf64;
5162
5163 if (::fstat64(fd, &buf64) >= 0) {
5164 mode = buf64.st_mode;
5165 if (S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) {
5166 /*
5167 * XXX: is the following call interruptible? If so, this might
5168 * need to go through the INTERRUPT_IO() wrapper as for other
5169 * blocking, interruptible calls in this file.
5170 */
5171 int n;
5172 if (::ioctl(fd, FIONREAD, &n) >= 0) {
5173 *bytes = n;
5174 return 1;
5175 }
5176 }
5177 }
5178 if ((cur = ::lseek64(fd, 0L, SEEK_CUR)) == -1) {
5179 return 0;
5180 } else if ((end = ::lseek64(fd, 0L, SEEK_END)) == -1) {
5181 return 0;
5182 } else if (::lseek64(fd, cur, SEEK_SET) == -1) {
5183 return 0;
5184 }
5185 *bytes = end - cur;
5186 return 1;
5187 }
5188
5189 int os::socket_available(int fd, jint *pbytes) {
5190 // Linux doc says EINTR not returned, unlike Solaris
5191 int ret = ::ioctl(fd, FIONREAD, pbytes);
5192
5193 //%% note ioctl can return 0 when successful, JVM_SocketAvailable
5194 // is expected to return 0 on failure and 1 on success to the jdk.
5195 return (ret < 0) ? 0 : 1;
5196 }
5197
5198 // Map a block of memory.
5199 char* os::pd_map_memory(int fd, const char* file_name, size_t file_offset,
5200 char *addr, size_t bytes, bool read_only,
5201 bool allow_exec) {
5202 int prot;
5203 int flags = MAP_PRIVATE;
5204
5205 if (read_only) {
5206 prot = PROT_READ;
5207 } else {
5208 prot = PROT_READ | PROT_WRITE;
5209 }
5210
5211 if (allow_exec) {
5212 prot |= PROT_EXEC;
5213 }
5214
5215 if (addr != NULL) {
5216 flags |= MAP_FIXED;
5217 }
5218
5219 char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags,
5220 fd, file_offset);
5221 if (mapped_address == MAP_FAILED) {
5222 return NULL;
5223 }
5224 return mapped_address;
5225 }
5226
5227
5228 // Remap a block of memory.
5229 char* os::pd_remap_memory(int fd, const char* file_name, size_t file_offset,
5230 char *addr, size_t bytes, bool read_only,
5231 bool allow_exec) {
5232 // same as map_memory() on this OS
5233 return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only,
5234 allow_exec);
5235 }
5236
5237
5238 // Unmap a block of memory.
5239 bool os::pd_unmap_memory(char* addr, size_t bytes) {
5240 return munmap(addr, bytes) == 0;
5241 }
5242
5243 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time);
5244
5245 static clockid_t thread_cpu_clockid(Thread* thread) {
5246 pthread_t tid = thread->osthread()->pthread_id();
5247 clockid_t clockid;
5248
5249 // Get thread clockid
5250 int rc = os::Linux::pthread_getcpuclockid(tid, &clockid);
5251 assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code");
5252 return clockid;
5253 }
5254
5255 // current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool)
5256 // are used by JVM M&M and JVMTI to get user+sys or user CPU time
5257 // of a thread.
5258 //
5259 // current_thread_cpu_time() and thread_cpu_time(Thread*) returns
5260 // the fast estimate available on the platform.
5261
5262 jlong os::current_thread_cpu_time() {
5263 if (os::Linux::supports_fast_thread_cpu_time()) {
5264 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
5265 } else {
5266 // return user + sys since the cost is the same
5267 return slow_thread_cpu_time(Thread::current(), true /* user + sys */);
5268 }
5269 }
5270
5271 jlong os::thread_cpu_time(Thread* thread) {
5272 // consistent with what current_thread_cpu_time() returns
5273 if (os::Linux::supports_fast_thread_cpu_time()) {
5274 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread));
5275 } else {
5276 return slow_thread_cpu_time(thread, true /* user + sys */);
5277 }
5278 }
5279
5280 jlong os::current_thread_cpu_time(bool user_sys_cpu_time) {
5281 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
5282 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
5283 } else {
5284 return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time);
5285 }
5286 }
5287
5288 jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
5289 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
5290 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread));
5291 } else {
5292 return slow_thread_cpu_time(thread, user_sys_cpu_time);
5293 }
5294 }
5295
5296 //
5297 // -1 on error.
5298 //
5299
5300 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
5301 static bool proc_task_unchecked = true;
5302 pid_t tid = thread->osthread()->thread_id();
5303 char *s;
5304 char stat[2048];
5305 int statlen;
5306 char proc_name[64];
5307 int count;
5308 long sys_time, user_time;
5309 char cdummy;
5310 int idummy;
5311 long ldummy;
5312 FILE *fp;
5313
5314 snprintf(proc_name, 64, "/proc/%d/stat", tid);
5315
5316 // The /proc/<tid>/stat aggregates per-process usage on
5317 // new Linux kernels 2.6+ where NPTL is supported.
5318 // The /proc/self/task/<tid>/stat still has the per-thread usage.
5319 // See bug 6328462.
5320 // There possibly can be cases where there is no directory
5321 // /proc/self/task, so we check its availability.
5322 if (proc_task_unchecked && os::Linux::is_NPTL()) {
5323 // This is executed only once
5324 proc_task_unchecked = false;
5325 fp = fopen("/proc/self/task", "r");
5326 if (fp != NULL) {
5327 snprintf(proc_name, 64, "/proc/self/task/%d/stat", tid);
5328 fclose(fp);
5329 }
5330 }
5331
5332 fp = fopen(proc_name, "r");
5333 if ( fp == NULL ) return -1;
5334 statlen = fread(stat, 1, 2047, fp);
5335 stat[statlen] = '\0';
5336 fclose(fp);
5337
5338 // Skip pid and the command string. Note that we could be dealing with
5339 // weird command names, e.g. user could decide to rename java launcher
5340 // to "java 1.4.2 :)", then the stat file would look like
5341 // 1234 (java 1.4.2 :)) R ... ...
5342 // We don't really need to know the command string, just find the last
5343 // occurrence of ")" and then start parsing from there. See bug 4726580.
5344 s = strrchr(stat, ')');
5345 if (s == NULL ) return -1;
5346
5347 // Skip blank chars
5348 do s++; while (isspace(*s));
5349
5350 count = sscanf(s,"%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu",
5351 &cdummy, &idummy, &idummy, &idummy, &idummy, &idummy,
5352 &ldummy, &ldummy, &ldummy, &ldummy, &ldummy,
5353 &user_time, &sys_time);
5354 if ( count != 13 ) return -1;
5355 if (user_sys_cpu_time) {
5356 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec);
5357 } else {
5358 return (jlong)user_time * (1000000000 / clock_tics_per_sec);
5359 }
5360 }
5361
5362 void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
5363 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits
5364 info_ptr->may_skip_backward = false; // elapsed time not wall time
5365 info_ptr->may_skip_forward = false; // elapsed time not wall time
5366 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned
5367 }
5368
5369 void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
5370 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits
5371 info_ptr->may_skip_backward = false; // elapsed time not wall time
5372 info_ptr->may_skip_forward = false; // elapsed time not wall time
5373 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned
5374 }
5375
5376 bool os::is_thread_cpu_time_supported() {
5377 return true;
5378 }
5379
5380 // System loadavg support. Returns -1 if load average cannot be obtained.
5381 // Linux doesn't yet have a (official) notion of processor sets,
5382 // so just return the system wide load average.
5383 int os::loadavg(double loadavg[], int nelem) {
5384 return ::getloadavg(loadavg, nelem);
5385 }
5386
5387 void os::pause() {
5388 char filename[MAX_PATH];
5389 if (PauseAtStartupFile && PauseAtStartupFile[0]) {
5390 jio_snprintf(filename, MAX_PATH, PauseAtStartupFile);
5391 } else {
5392 jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id());
5393 }
5394
5395 int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
5396 if (fd != -1) {
5397 struct stat buf;
5398 ::close(fd);
5399 while (::stat(filename, &buf) == 0) {
5400 (void)::poll(NULL, 0, 100);
5401 }
5402 } else {
5403 jio_fprintf(stderr,
5404 "Could not open pause file '%s', continuing immediately.\n", filename);
5405 }
5406 }
5407
5408
5409 // Refer to the comments in os_solaris.cpp park-unpark.
5410 //
5411 // Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can
5412 // hang indefinitely. For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable.
5413 // For specifics regarding the bug see GLIBC BUGID 261237 :
5414 // http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html.
5415 // Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future
5416 // will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar
5417 // is used. (The simple C test-case provided in the GLIBC bug report manifests the
5418 // hang). The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos()
5419 // and monitorenter when we're using 1-0 locking. All those operations may result in
5420 // calls to pthread_cond_timedwait(). Using LD_ASSUME_KERNEL to use an older version
5421 // of libpthread avoids the problem, but isn't practical.
5422 //
5423 // Possible remedies:
5424 //
5425 // 1. Establish a minimum relative wait time. 50 to 100 msecs seems to work.
5426 // This is palliative and probabilistic, however. If the thread is preempted
5427 // between the call to compute_abstime() and pthread_cond_timedwait(), more
5428 // than the minimum period may have passed, and the abstime may be stale (in the
5429 // past) resultin in a hang. Using this technique reduces the odds of a hang
5430 // but the JVM is still vulnerable, particularly on heavily loaded systems.
5431 //
5432 // 2. Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead
5433 // of the usual flag-condvar-mutex idiom. The write side of the pipe is set
5434 // NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo)
5435 // reduces to poll()+read(). This works well, but consumes 2 FDs per extant
5436 // thread.
5437 //
5438 // 3. Embargo pthread_cond_timedwait() and implement a native "chron" thread
5439 // that manages timeouts. We'd emulate pthread_cond_timedwait() by enqueuing
5440 // a timeout request to the chron thread and then blocking via pthread_cond_wait().
5441 // This also works well. In fact it avoids kernel-level scalability impediments
5442 // on certain platforms that don't handle lots of active pthread_cond_timedwait()
5443 // timers in a graceful fashion.
5444 //
5445 // 4. When the abstime value is in the past it appears that control returns
5446 // correctly from pthread_cond_timedwait(), but the condvar is left corrupt.
5447 // Subsequent timedwait/wait calls may hang indefinitely. Given that, we
5448 // can avoid the problem by reinitializing the condvar -- by cond_destroy()
5449 // followed by cond_init() -- after all calls to pthread_cond_timedwait().
5450 // It may be possible to avoid reinitialization by checking the return
5451 // value from pthread_cond_timedwait(). In addition to reinitializing the
5452 // condvar we must establish the invariant that cond_signal() is only called
5453 // within critical sections protected by the adjunct mutex. This prevents
5454 // cond_signal() from "seeing" a condvar that's in the midst of being
5455 // reinitialized or that is corrupt. Sadly, this invariant obviates the
5456 // desirable signal-after-unlock optimization that avoids futile context switching.
5457 //
5458 // I'm also concerned that some versions of NTPL might allocate an auxilliary
5459 // structure when a condvar is used or initialized. cond_destroy() would
5460 // release the helper structure. Our reinitialize-after-timedwait fix
5461 // put excessive stress on malloc/free and locks protecting the c-heap.
5462 //
5463 // We currently use (4). See the WorkAroundNTPLTimedWaitHang flag.
5464 // It may be possible to refine (4) by checking the kernel and NTPL verisons
5465 // and only enabling the work-around for vulnerable environments.
5466
5467 // utility to compute the abstime argument to timedwait:
5468 // millis is the relative timeout time
5469 // abstime will be the absolute timeout time
5470 // TODO: replace compute_abstime() with unpackTime()
5471
5472 static struct timespec* compute_abstime(timespec* abstime, jlong millis) {
5473 if (millis < 0) millis = 0;
5474
5475 jlong seconds = millis / 1000;
5476 millis %= 1000;
5477 if (seconds > 50000000) { // see man cond_timedwait(3T)
5478 seconds = 50000000;
5479 }
5480
5481 if (os::supports_monotonic_clock()) {
5482 struct timespec now;
5483 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now);
5484 assert_status(status == 0, status, "clock_gettime");
5485 abstime->tv_sec = now.tv_sec + seconds;
5486 long nanos = now.tv_nsec + millis * NANOSECS_PER_MILLISEC;
5487 if (nanos >= NANOSECS_PER_SEC) {
5488 abstime->tv_sec += 1;
5489 nanos -= NANOSECS_PER_SEC;
5490 }
5491 abstime->tv_nsec = nanos;
5492 } else {
5493 struct timeval now;
5494 int status = gettimeofday(&now, NULL);
5495 assert(status == 0, "gettimeofday");
5496 abstime->tv_sec = now.tv_sec + seconds;
5497 long usec = now.tv_usec + millis * 1000;
5498 if (usec >= 1000000) {
5499 abstime->tv_sec += 1;
5500 usec -= 1000000;
5501 }
5502 abstime->tv_nsec = usec * 1000;
5503 }
5504 return abstime;
5505 }
5506
5507
5508 // Test-and-clear _Event, always leaves _Event set to 0, returns immediately.
5509 // Conceptually TryPark() should be equivalent to park(0).
5510
5511 int os::PlatformEvent::TryPark() {
5512 for (;;) {
5513 const int v = _Event ;
5514 guarantee ((v == 0) || (v == 1), "invariant") ;
5515 if (Atomic::cmpxchg (0, &_Event, v) == v) return v ;
5516 }
5517 }
5518
5519 void os::PlatformEvent::park() { // AKA "down()"
5520 // Invariant: Only the thread associated with the Event/PlatformEvent
5521 // may call park().
5522 // TODO: assert that _Assoc != NULL or _Assoc == Self
5523 int v ;
5524 for (;;) {
5525 v = _Event ;
5526 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ;
5527 }
5528 guarantee (v >= 0, "invariant") ;
5529 if (v == 0) {
5530 // Do this the hard way by blocking ...
5531 int status = pthread_mutex_lock(_mutex);
5532 assert_status(status == 0, status, "mutex_lock");
5533 guarantee (_nParked == 0, "invariant") ;
5534 ++ _nParked ;
5535 while (_Event < 0) {
5536 status = pthread_cond_wait(_cond, _mutex);
5537 // for some reason, under 2.7 lwp_cond_wait() may return ETIME ...
5538 // Treat this the same as if the wait was interrupted
5539 if (status == ETIME) { status = EINTR; }
5540 assert_status(status == 0 || status == EINTR, status, "cond_wait");
5541 }
5542 -- _nParked ;
5543
5544 _Event = 0 ;
5545 status = pthread_mutex_unlock(_mutex);
5546 assert_status(status == 0, status, "mutex_unlock");
5547 // Paranoia to ensure our locked and lock-free paths interact
5548 // correctly with each other.
5549 OrderAccess::fence();
5550 }
5551 guarantee (_Event >= 0, "invariant") ;
5552 }
5553
5554 int os::PlatformEvent::park(jlong millis) {
5555 guarantee (_nParked == 0, "invariant") ;
5556
5557 int v ;
5558 for (;;) {
5559 v = _Event ;
5560 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ;
5561 }
5562 guarantee (v >= 0, "invariant") ;
5563 if (v != 0) return OS_OK ;
5564
5565 // We do this the hard way, by blocking the thread.
5566 // Consider enforcing a minimum timeout value.
5567 struct timespec abst;
5568 compute_abstime(&abst, millis);
5569
5570 int ret = OS_TIMEOUT;
5571 int status = pthread_mutex_lock(_mutex);
5572 assert_status(status == 0, status, "mutex_lock");
5573 guarantee (_nParked == 0, "invariant") ;
5574 ++_nParked ;
5575
5576 // Object.wait(timo) will return because of
5577 // (a) notification
5578 // (b) timeout
5579 // (c) thread.interrupt
5580 //
5581 // Thread.interrupt and object.notify{All} both call Event::set.
5582 // That is, we treat thread.interrupt as a special case of notification.
5583 // The underlying Solaris implementation, cond_timedwait, admits
5584 // spurious/premature wakeups, but the JLS/JVM spec prevents the
5585 // JVM from making those visible to Java code. As such, we must
5586 // filter out spurious wakeups. We assume all ETIME returns are valid.
5587 //
5588 // TODO: properly differentiate simultaneous notify+interrupt.
5589 // In that case, we should propagate the notify to another waiter.
5590
5591 while (_Event < 0) {
5592 status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst);
5593 if (status != 0 && WorkAroundNPTLTimedWaitHang) {
5594 pthread_cond_destroy (_cond);
5595 pthread_cond_init (_cond, os::Linux::condAttr()) ;
5596 }
5597 assert_status(status == 0 || status == EINTR ||
5598 status == ETIME || status == ETIMEDOUT,
5599 status, "cond_timedwait");
5600 if (!FilterSpuriousWakeups) break ; // previous semantics
5601 if (status == ETIME || status == ETIMEDOUT) break ;
5602 // We consume and ignore EINTR and spurious wakeups.
5603 }
5604 --_nParked ;
5605 if (_Event >= 0) {
5606 ret = OS_OK;
5607 }
5608 _Event = 0 ;
5609 status = pthread_mutex_unlock(_mutex);
5610 assert_status(status == 0, status, "mutex_unlock");
5611 assert (_nParked == 0, "invariant") ;
5612 // Paranoia to ensure our locked and lock-free paths interact
5613 // correctly with each other.
5614 OrderAccess::fence();
5615 return ret;
5616 }
5617
5618 void os::PlatformEvent::unpark() {
5619 // Transitions for _Event:
5620 // 0 :=> 1
5621 // 1 :=> 1
5622 // -1 :=> either 0 or 1; must signal target thread
5623 // That is, we can safely transition _Event from -1 to either
5624 // 0 or 1. Forcing 1 is slightly more efficient for back-to-back
5625 // unpark() calls.
5626 // See also: "Semaphores in Plan 9" by Mullender & Cox
5627 //
5628 // Note: Forcing a transition from "-1" to "1" on an unpark() means
5629 // that it will take two back-to-back park() calls for the owning
5630 // thread to block. This has the benefit of forcing a spurious return
5631 // from the first park() call after an unpark() call which will help
5632 // shake out uses of park() and unpark() without condition variables.
5633
5634 if (Atomic::xchg(1, &_Event) >= 0) return;
5635
5636 // Wait for the thread associated with the event to vacate
5637 int status = pthread_mutex_lock(_mutex);
5638 assert_status(status == 0, status, "mutex_lock");
5639 int AnyWaiters = _nParked;
5640 assert(AnyWaiters == 0 || AnyWaiters == 1, "invariant");
5641 if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) {
5642 AnyWaiters = 0;
5643 pthread_cond_signal(_cond);
5644 }
5645 status = pthread_mutex_unlock(_mutex);
5646 assert_status(status == 0, status, "mutex_unlock");
5647 if (AnyWaiters != 0) {
5648 status = pthread_cond_signal(_cond);
5649 assert_status(status == 0, status, "cond_signal");
5650 }
5651
5652 // Note that we signal() _after dropping the lock for "immortal" Events.
5653 // This is safe and avoids a common class of futile wakeups. In rare
5654 // circumstances this can cause a thread to return prematurely from
5655 // cond_{timed}wait() but the spurious wakeup is benign and the victim will
5656 // simply re-test the condition and re-park itself.
5657 }
5658
5659
5660 // JSR166
5661 // -------------------------------------------------------
5662
5663 /*
5664 * The solaris and linux implementations of park/unpark are fairly
5665 * conservative for now, but can be improved. They currently use a
5666 * mutex/condvar pair, plus a a count.
5667 * Park decrements count if > 0, else does a condvar wait. Unpark
5668 * sets count to 1 and signals condvar. Only one thread ever waits
5669 * on the condvar. Contention seen when trying to park implies that someone
5670 * is unparking you, so don't wait. And spurious returns are fine, so there
5671 * is no need to track notifications.
5672 */
5673
5674 /*
5675 * This code is common to linux and solaris and will be moved to a
5676 * common place in dolphin.
5677 *
5678 * The passed in time value is either a relative time in nanoseconds
5679 * or an absolute time in milliseconds. Either way it has to be unpacked
5680 * into suitable seconds and nanoseconds components and stored in the
5681 * given timespec structure.
5682 * Given time is a 64-bit value and the time_t used in the timespec is only
5683 * a signed-32-bit value (except on 64-bit Linux) we have to watch for
5684 * overflow if times way in the future are given. Further on Solaris versions
5685 * prior to 10 there is a restriction (see cond_timedwait) that the specified
5686 * number of seconds, in abstime, is less than current_time + 100,000,000.
5687 * As it will be 28 years before "now + 100000000" will overflow we can
5688 * ignore overflow and just impose a hard-limit on seconds using the value
5689 * of "now + 100,000,000". This places a limit on the timeout of about 3.17
5690 * years from "now".
5691 */
5692
5693 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) {
5694 assert (time > 0, "convertTime");
5695 time_t max_secs = 0;
5696
5697 if (!os::supports_monotonic_clock() || isAbsolute) {
5698 struct timeval now;
5699 int status = gettimeofday(&now, NULL);
5700 assert(status == 0, "gettimeofday");
5701
5702 max_secs = now.tv_sec + MAX_SECS;
5703
5704 if (isAbsolute) {
5705 jlong secs = time / 1000;
5706 if (secs > max_secs) {
5707 absTime->tv_sec = max_secs;
5708 } else {
5709 absTime->tv_sec = secs;
5710 }
5711 absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC;
5712 } else {
5713 jlong secs = time / NANOSECS_PER_SEC;
5714 if (secs >= MAX_SECS) {
5715 absTime->tv_sec = max_secs;
5716 absTime->tv_nsec = 0;
5717 } else {
5718 absTime->tv_sec = now.tv_sec + secs;
5719 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000;
5720 if (absTime->tv_nsec >= NANOSECS_PER_SEC) {
5721 absTime->tv_nsec -= NANOSECS_PER_SEC;
5722 ++absTime->tv_sec; // note: this must be <= max_secs
5723 }
5724 }
5725 }
5726 } else {
5727 // must be relative using monotonic clock
5728 struct timespec now;
5729 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now);
5730 assert_status(status == 0, status, "clock_gettime");
5731 max_secs = now.tv_sec + MAX_SECS;
5732 jlong secs = time / NANOSECS_PER_SEC;
5733 if (secs >= MAX_SECS) {
5734 absTime->tv_sec = max_secs;
5735 absTime->tv_nsec = 0;
5736 } else {
5737 absTime->tv_sec = now.tv_sec + secs;
5738 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_nsec;
5739 if (absTime->tv_nsec >= NANOSECS_PER_SEC) {
5740 absTime->tv_nsec -= NANOSECS_PER_SEC;
5741 ++absTime->tv_sec; // note: this must be <= max_secs
5742 }
5743 }
5744 }
5745 assert(absTime->tv_sec >= 0, "tv_sec < 0");
5746 assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs");
5747 assert(absTime->tv_nsec >= 0, "tv_nsec < 0");
5748 assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec");
5749 }
5750
5751 void Parker::park(bool isAbsolute, jlong time) {
5752 // Ideally we'd do something useful while spinning, such
5753 // as calling unpackTime().
5754
5755 // Optional fast-path check:
5756 // Return immediately if a permit is available.
5757 // We depend on Atomic::xchg() having full barrier semantics
5758 // since we are doing a lock-free update to _counter.
5759 if (Atomic::xchg(0, &_counter) > 0) return;
5760
5761 Thread* thread = Thread::current();
5762 assert(thread->is_Java_thread(), "Must be JavaThread");
5763 JavaThread *jt = (JavaThread *)thread;
5764
5765 // Optional optimization -- avoid state transitions if there's an interrupt pending.
5766 // Check interrupt before trying to wait
5767 if (Thread::is_interrupted(thread, false)) {
5768 return;
5769 }
5770
5771 // Next, demultiplex/decode time arguments
5772 timespec absTime;
5773 if (time < 0 || (isAbsolute && time == 0) ) { // don't wait at all
5774 return;
5775 }
5776 if (time > 0) {
5777 unpackTime(&absTime, isAbsolute, time);
5778 }
5779
5780
5781 // Enter safepoint region
5782 // Beware of deadlocks such as 6317397.
5783 // The per-thread Parker:: mutex is a classic leaf-lock.
5784 // In particular a thread must never block on the Threads_lock while
5785 // holding the Parker:: mutex. If safepoints are pending both the
5786 // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock.
5787 ThreadBlockInVM tbivm(jt);
5788
5789 // Don't wait if cannot get lock since interference arises from
5790 // unblocking. Also. check interrupt before trying wait
5791 if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) {
5792 return;
5793 }
5794
5795 int status ;
5796 if (_counter > 0) { // no wait needed
5797 _counter = 0;
5798 status = pthread_mutex_unlock(_mutex);
5799 assert (status == 0, "invariant") ;
5800 // Paranoia to ensure our locked and lock-free paths interact
5801 // correctly with each other and Java-level accesses.
5802 OrderAccess::fence();
5803 return;
5804 }
5805
5806 #ifdef ASSERT
5807 // Don't catch signals while blocked; let the running threads have the signals.
5808 // (This allows a debugger to break into the running thread.)
5809 sigset_t oldsigs;
5810 sigset_t* allowdebug_blocked = os::Linux::allowdebug_blocked_signals();
5811 pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs);
5812 #endif
5813
5814 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */);
5815 jt->set_suspend_equivalent();
5816 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
5817
5818 assert(_cur_index == -1, "invariant");
5819 if (time == 0) {
5820 _cur_index = REL_INDEX; // arbitrary choice when not timed
5821 status = pthread_cond_wait (&_cond[_cur_index], _mutex) ;
5822 } else {
5823 _cur_index = isAbsolute ? ABS_INDEX : REL_INDEX;
5824 status = os::Linux::safe_cond_timedwait (&_cond[_cur_index], _mutex, &absTime) ;
5825 if (status != 0 && WorkAroundNPTLTimedWaitHang) {
5826 pthread_cond_destroy (&_cond[_cur_index]) ;
5827 pthread_cond_init (&_cond[_cur_index], isAbsolute ? NULL : os::Linux::condAttr());
5828 }
5829 }
5830 _cur_index = -1;
5831 assert_status(status == 0 || status == EINTR ||
5832 status == ETIME || status == ETIMEDOUT,
5833 status, "cond_timedwait");
5834
5835 #ifdef ASSERT
5836 pthread_sigmask(SIG_SETMASK, &oldsigs, NULL);
5837 #endif
5838
5839 _counter = 0 ;
5840 status = pthread_mutex_unlock(_mutex) ;
5841 assert_status(status == 0, status, "invariant") ;
5842 // Paranoia to ensure our locked and lock-free paths interact
5843 // correctly with each other and Java-level accesses.
5844 OrderAccess::fence();
5845
5846 // If externally suspended while waiting, re-suspend
5847 if (jt->handle_special_suspend_equivalent_condition()) {
5848 jt->java_suspend_self();
5849 }
5850 }
5851
5852 void Parker::unpark() {
5853 int s, status ;
5854 status = pthread_mutex_lock(_mutex);
5855 assert (status == 0, "invariant") ;
5856 s = _counter;
5857 _counter = 1;
5858 if (s < 1) {
5859 // thread might be parked
5860 if (_cur_index != -1) {
5861 // thread is definitely parked
5862 if (WorkAroundNPTLTimedWaitHang) {
5863 status = pthread_cond_signal (&_cond[_cur_index]);
5864 assert (status == 0, "invariant");
5865 status = pthread_mutex_unlock(_mutex);
5866 assert (status == 0, "invariant");
5867 } else {
5868 status = pthread_mutex_unlock(_mutex);
5869 assert (status == 0, "invariant");
5870 status = pthread_cond_signal (&_cond[_cur_index]);
5871 assert (status == 0, "invariant");
5872 }
5873 } else {
5874 pthread_mutex_unlock(_mutex);
5875 assert (status == 0, "invariant") ;
5876 }
5877 } else {
5878 pthread_mutex_unlock(_mutex);
5879 assert (status == 0, "invariant") ;
5880 }
5881 }
5882
5883
5884 extern char** environ;
5885
5886 #ifndef __NR_fork
5887 #define __NR_fork IA32_ONLY(2) IA64_ONLY(not defined) AMD64_ONLY(57)
5888 #endif
5889
5890 #ifndef __NR_execve
5891 #define __NR_execve IA32_ONLY(11) IA64_ONLY(1033) AMD64_ONLY(59)
5892 #endif
5893
5894 // Run the specified command in a separate process. Return its exit value,
5895 // or -1 on failure (e.g. can't fork a new process).
5896 // Unlike system(), this function can be called from signal handler. It
5897 // doesn't block SIGINT et al.
5898 int os::fork_and_exec(char* cmd) {
5899 const char * argv[4] = {"sh", "-c", cmd, NULL};
5900
5901 // fork() in LinuxThreads/NPTL is not async-safe. It needs to run
5902 // pthread_atfork handlers and reset pthread library. All we need is a
5903 // separate process to execve. Make a direct syscall to fork process.
5904 // On IA64 there's no fork syscall, we have to use fork() and hope for
5905 // the best...
5906 pid_t pid = NOT_IA64(syscall(__NR_fork);)
5907 IA64_ONLY(fork();)
5908
5909 if (pid < 0) {
5910 // fork failed
5911 return -1;
5912
5913 } else if (pid == 0) {
5914 // child process
5915
5916 // execve() in LinuxThreads will call pthread_kill_other_threads_np()
5917 // first to kill every thread on the thread list. Because this list is
5918 // not reset by fork() (see notes above), execve() will instead kill
5919 // every thread in the parent process. We know this is the only thread
5920 // in the new process, so make a system call directly.
5921 // IA64 should use normal execve() from glibc to match the glibc fork()
5922 // above.
5923 NOT_IA64(syscall(__NR_execve, "/bin/sh", argv, environ);)
5924 IA64_ONLY(execve("/bin/sh", (char* const*)argv, environ);)
5925
5926 // execve failed
5927 _exit(-1);
5928
5929 } else {
5930 // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't
5931 // care about the actual exit code, for now.
5932
5933 int status;
5934
5935 // Wait for the child process to exit. This returns immediately if
5936 // the child has already exited. */
5937 while (waitpid(pid, &status, 0) < 0) {
5938 switch (errno) {
5939 case ECHILD: return 0;
5940 case EINTR: break;
5941 default: return -1;
5942 }
5943 }
5944
5945 if (WIFEXITED(status)) {
5946 // The child exited normally; get its exit code.
5947 return WEXITSTATUS(status);
5948 } else if (WIFSIGNALED(status)) {
5949 // The child exited because of a signal
5950 // The best value to return is 0x80 + signal number,
5951 // because that is what all Unix shells do, and because
5952 // it allows callers to distinguish between process exit and
5953 // process death by signal.
5954 return 0x80 + WTERMSIG(status);
5955 } else {
5956 // Unknown exit code; pass it through
5957 return status;
5958 }
5959 }
5960 }
5961
5962 // is_headless_jre()
5963 //
5964 // Test for the existence of xawt/libmawt.so or libawt_xawt.so
5965 // in order to report if we are running in a headless jre
5966 //
5967 // Since JDK8 xawt/libmawt.so was moved into the same directory
5968 // as libawt.so, and renamed libawt_xawt.so
5969 //
5970 bool os::is_headless_jre() {
5971 struct stat statbuf;
5972 char buf[MAXPATHLEN];
5973 char libmawtpath[MAXPATHLEN];
5974 const char *xawtstr = "/xawt/libmawt.so";
5975 const char *new_xawtstr = "/libawt_xawt.so";
5976 char *p;
5977
5978 // Get path to libjvm.so
5979 os::jvm_path(buf, sizeof(buf));
5980
5981 // Get rid of libjvm.so
5982 p = strrchr(buf, '/');
5983 if (p == NULL) return false;
5984 else *p = '\0';
5985
5986 // Get rid of client or server
5987 p = strrchr(buf, '/');
5988 if (p == NULL) return false;
5989 else *p = '\0';
5990
5991 // check xawt/libmawt.so
5992 strcpy(libmawtpath, buf);
5993 strcat(libmawtpath, xawtstr);
5994 if (::stat(libmawtpath, &statbuf) == 0) return false;
5995
5996 // check libawt_xawt.so
5997 strcpy(libmawtpath, buf);
5998 strcat(libmawtpath, new_xawtstr);
5999 if (::stat(libmawtpath, &statbuf) == 0) return false;
6000
6001 return true;
6002 }
6003
6004 // Get the default path to the core file
6005 // Returns the length of the string
6006 int os::get_core_path(char* buffer, size_t bufferSize) {
6007 const char* p = get_current_directory(buffer, bufferSize);
6008
6009 if (p == NULL) {
6010 assert(p != NULL, "failed to get current directory");
6011 return 0;
6012 }
6013
6014 return strlen(buffer);
6015 }
6016
6017 #ifdef JAVASE_EMBEDDED
6018 //
6019 // A thread to watch the '/dev/mem_notify' device, which will tell us when the OS is running low on memory.
6020 //
6021 MemNotifyThread* MemNotifyThread::_memnotify_thread = NULL;
6022
6023 // ctor
6024 //
6025 MemNotifyThread::MemNotifyThread(int fd): Thread() {
6026 assert(memnotify_thread() == NULL, "we can only allocate one MemNotifyThread");
6027 _fd = fd;
6028
6029 if (os::create_thread(this, os::os_thread)) {
6030 _memnotify_thread = this;
6031 os::set_priority(this, NearMaxPriority);
6032 os::start_thread(this);
6033 }
6034 }
6035
6036 // Where all the work gets done
6037 //
6038 void MemNotifyThread::run() {
6039 assert(this == memnotify_thread(), "expected the singleton MemNotifyThread");
6040
6041 // Set up the select arguments
6042 fd_set rfds;
6043 if (_fd != -1) {
6044 FD_ZERO(&rfds);
6045 FD_SET(_fd, &rfds);
6046 }
6047
6048 // Now wait for the mem_notify device to wake up
6049 while (1) {
6050 // Wait for the mem_notify device to signal us..
6051 int rc = select(_fd+1, _fd != -1 ? &rfds : NULL, NULL, NULL, NULL);
6052 if (rc == -1) {
6053 perror("select!\n");
6054 break;
6055 } else if (rc) {
6056 //ssize_t free_before = os::available_memory();
6057 //tty->print ("Notified: Free: %dK \n",os::available_memory()/1024);
6058
6059 // The kernel is telling us there is not much memory left...
6060 // try to do something about that
6061
6062 // If we are not already in a GC, try one.
6063 if (!Universe::heap()->is_gc_active()) {
6064 Universe::heap()->collect(GCCause::_allocation_failure);
6065
6066 //ssize_t free_after = os::available_memory();
6067 //tty->print ("Post-Notify: Free: %dK\n",free_after/1024);
6068 //tty->print ("GC freed: %dK\n", (free_after - free_before)/1024);
6069 }
6070 // We might want to do something like the following if we find the GC's are not helping...
6071 // Universe::heap()->size_policy()->set_gc_time_limit_exceeded(true);
6072 }
6073 }
6074 }
6075
6076 //
6077 // See if the /dev/mem_notify device exists, and if so, start a thread to monitor it.
6078 //
6079 void MemNotifyThread::start() {
6080 int fd;
6081 fd = open ("/dev/mem_notify", O_RDONLY, 0);
6082 if (fd < 0) {
6083 return;
6084 }
6085
6086 if (memnotify_thread() == NULL) {
6087 new MemNotifyThread(fd);
6088 }
6089 }
6090
6091 #endif // JAVASE_EMBEDDED
6092
6093
6094 /////////////// Unit tests ///////////////
6095
6096 #ifndef PRODUCT
6097
6098 #define test_log(...) \
6099 do {\
6100 if (VerboseInternalVMTests) { \
6101 tty->print_cr(__VA_ARGS__); \
6102 tty->flush(); \
6103 }\
6104 } while (false)
6105
6106 class TestReserveMemorySpecial : AllStatic {
6107 public:
6108 static void small_page_write(void* addr, size_t size) {
6109 size_t page_size = os::vm_page_size();
6110
6111 char* end = (char*)addr + size;
6112 for (char* p = (char*)addr; p < end; p += page_size) {
6113 *p = 1;
6114 }
6115 }
6116
6117 static void test_reserve_memory_special_huge_tlbfs_only(size_t size) {
6118 if (!UseHugeTLBFS) {
6119 return;
6120 }
6121
6122 test_log("test_reserve_memory_special_huge_tlbfs_only(" SIZE_FORMAT ")", size);
6123
6124 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_only(size, NULL, false);
6125
6126 if (addr != NULL) {
6127 small_page_write(addr, size);
6128
6129 os::Linux::release_memory_special_huge_tlbfs(addr, size);
6130 }
6131 }
6132
6133 static void test_reserve_memory_special_huge_tlbfs_only() {
6134 if (!UseHugeTLBFS) {
6135 return;
6136 }
6137
6138 size_t lp = os::large_page_size();
6139
6140 for (size_t size = lp; size <= lp * 10; size += lp) {
6141 test_reserve_memory_special_huge_tlbfs_only(size);
6142 }
6143 }
6144
6145 static void test_reserve_memory_special_huge_tlbfs_mixed(size_t size, size_t alignment) {
6146 if (!UseHugeTLBFS) {
6147 return;
6148 }
6149
6150 test_log("test_reserve_memory_special_huge_tlbfs_mixed(" SIZE_FORMAT ", " SIZE_FORMAT ")",
6151 size, alignment);
6152
6153 assert(size >= os::large_page_size(), "Incorrect input to test");
6154
6155 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, NULL, false);
6156
6157 if (addr != NULL) {
6158 small_page_write(addr, size);
6159
6160 os::Linux::release_memory_special_huge_tlbfs(addr, size);
6161 }
6162 }
6163
6164 static void test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(size_t size) {
6165 size_t lp = os::large_page_size();
6166 size_t ag = os::vm_allocation_granularity();
6167
6168 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) {
6169 test_reserve_memory_special_huge_tlbfs_mixed(size, alignment);
6170 }
6171 }
6172
6173 static void test_reserve_memory_special_huge_tlbfs_mixed() {
6174 size_t lp = os::large_page_size();
6175 size_t ag = os::vm_allocation_granularity();
6176
6177 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp);
6178 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + ag);
6179 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + lp / 2);
6180 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2);
6181 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 + ag);
6182 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 - ag);
6183 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 + lp / 2);
6184 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10);
6185 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10 + lp / 2);
6186 }
6187
6188 static void test_reserve_memory_special_huge_tlbfs() {
6189 if (!UseHugeTLBFS) {
6190 return;
6191 }
6192
6193 test_reserve_memory_special_huge_tlbfs_only();
6194 test_reserve_memory_special_huge_tlbfs_mixed();
6195 }
6196
6197 static void test_reserve_memory_special_shm(size_t size, size_t alignment) {
6198 if (!UseSHM) {
6199 return;
6200 }
6201
6202 test_log("test_reserve_memory_special_shm(" SIZE_FORMAT ", " SIZE_FORMAT ")", size, alignment);
6203
6204 char* addr = os::Linux::reserve_memory_special_shm(size, alignment, NULL, false);
6205
6206 if (addr != NULL) {
6207 assert(is_ptr_aligned(addr, alignment), "Check");
6208 assert(is_ptr_aligned(addr, os::large_page_size()), "Check");
6209
6210 small_page_write(addr, size);
6211
6212 os::Linux::release_memory_special_shm(addr, size);
6213 }
6214 }
6215
6216 static void test_reserve_memory_special_shm() {
6217 size_t lp = os::large_page_size();
6218 size_t ag = os::vm_allocation_granularity();
6219
6220 for (size_t size = ag; size < lp * 3; size += ag) {
6221 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) {
6222 test_reserve_memory_special_shm(size, alignment);
6223 }
6224 }
6225 }
6226
6227 static void test() {
6228 test_reserve_memory_special_huge_tlbfs();
6229 test_reserve_memory_special_shm();
6230 }
6231 };
6232
6233 void TestReserveMemorySpecial_test() {
6234 TestReserveMemorySpecial::test();
6235 }
6236
6237 #endif