Tue, 04 Sep 2018 21:25:12 +0800
#7517 mRegP match a0_RegP
1 /*
2 * Copyright (c) 1999, 2016, 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 */
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/orderAccess.inline.hpp"
53 #include "runtime/osThread.hpp"
54 #include "runtime/perfMemory.hpp"
55 #include "runtime/sharedRuntime.hpp"
56 #include "runtime/statSampler.hpp"
57 #include "runtime/stubRoutines.hpp"
58 #include "runtime/thread.inline.hpp"
59 #include "runtime/threadCritical.hpp"
60 #include "runtime/timer.hpp"
61 #include "services/attachListener.hpp"
62 #include "services/memTracker.hpp"
63 #include "services/runtimeService.hpp"
64 #include "utilities/decoder.hpp"
65 #include "utilities/defaultStream.hpp"
66 #include "utilities/events.hpp"
67 #include "utilities/elfFile.hpp"
68 #include "utilities/growableArray.hpp"
69 #include "utilities/vmError.hpp"
71 // put OS-includes here
72 # include <sys/types.h>
73 # include <sys/mman.h>
74 # include <sys/stat.h>
75 # include <sys/select.h>
76 # include <pthread.h>
77 # include <signal.h>
78 # include <errno.h>
79 # include <dlfcn.h>
80 # include <stdio.h>
81 # include <unistd.h>
82 # include <sys/resource.h>
83 # include <pthread.h>
84 # include <sys/stat.h>
85 # include <sys/time.h>
86 # include <sys/times.h>
87 # include <sys/utsname.h>
88 # include <sys/socket.h>
89 # include <sys/wait.h>
90 # include <pwd.h>
91 # include <poll.h>
92 # include <semaphore.h>
93 # include <fcntl.h>
94 # include <string.h>
95 # include <syscall.h>
96 # include <sys/sysinfo.h>
97 # include <gnu/libc-version.h>
98 # include <sys/ipc.h>
99 # include <sys/shm.h>
100 # include <link.h>
101 # include <stdint.h>
102 # include <inttypes.h>
103 # include <sys/ioctl.h>
105 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
107 #ifndef _GNU_SOURCE
108 #define _GNU_SOURCE
109 #include <sched.h>
110 #undef _GNU_SOURCE
111 #else
112 #include <sched.h>
113 #endif
115 // if RUSAGE_THREAD for getrusage() has not been defined, do it here. The code calling
116 // getrusage() is prepared to handle the associated failure.
117 #ifndef RUSAGE_THREAD
118 #define RUSAGE_THREAD (1) /* only the calling thread */
119 #endif
121 #define MAX_PATH (2 * K)
123 #define MAX_SECS 100000000
125 // for timer info max values which include all bits
126 #define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF)
128 #define LARGEPAGES_BIT (1 << 6)
129 ////////////////////////////////////////////////////////////////////////////////
130 // global variables
131 julong os::Linux::_physical_memory = 0;
133 address os::Linux::_initial_thread_stack_bottom = NULL;
134 uintptr_t os::Linux::_initial_thread_stack_size = 0;
136 int (*os::Linux::_clock_gettime)(clockid_t, struct timespec *) = NULL;
137 int (*os::Linux::_pthread_getcpuclockid)(pthread_t, clockid_t *) = NULL;
138 Mutex* os::Linux::_createThread_lock = NULL;
139 pthread_t os::Linux::_main_thread;
140 int os::Linux::_page_size = -1;
141 const int os::Linux::_vm_default_page_size = (8 * K);
142 bool os::Linux::_is_floating_stack = false;
143 bool os::Linux::_is_NPTL = false;
144 bool os::Linux::_supports_fast_thread_cpu_time = false;
145 const char * os::Linux::_glibc_version = NULL;
146 const char * os::Linux::_libpthread_version = NULL;
147 pthread_condattr_t os::Linux::_condattr[1];
149 static jlong initial_time_count=0;
151 static int clock_tics_per_sec = 100;
153 // For diagnostics to print a message once. see run_periodic_checks
154 static sigset_t check_signal_done;
155 static bool check_signals = true;
157 static pid_t _initial_pid = 0;
159 /* Signal number used to suspend/resume a thread */
161 /* do not use any signal number less than SIGSEGV, see 4355769 */
162 static int SR_signum = SIGUSR2;
163 sigset_t SR_sigset;
165 /* Used to protect dlsym() calls */
166 static pthread_mutex_t dl_mutex;
168 // Declarations
169 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time);
171 // utility functions
173 static int SR_initialize();
175 julong os::available_memory() {
176 return Linux::available_memory();
177 }
179 julong os::Linux::available_memory() {
180 // values in struct sysinfo are "unsigned long"
181 struct sysinfo si;
182 sysinfo(&si);
184 return (julong)si.freeram * si.mem_unit;
185 }
187 julong os::physical_memory() {
188 return Linux::physical_memory();
189 }
191 ////////////////////////////////////////////////////////////////////////////////
192 // environment support
194 bool os::getenv(const char* name, char* buf, int len) {
195 const char* val = ::getenv(name);
196 if (val != NULL && strlen(val) < (size_t)len) {
197 strcpy(buf, val);
198 return true;
199 }
200 if (len > 0) buf[0] = 0; // return a null string
201 return false;
202 }
205 // Return true if user is running as root.
207 bool os::have_special_privileges() {
208 static bool init = false;
209 static bool privileges = false;
210 if (!init) {
211 privileges = (getuid() != geteuid()) || (getgid() != getegid());
212 init = true;
213 }
214 return privileges;
215 }
218 #ifndef SYS_gettid
219 // i386: 224, ia64: 1105, amd64: 186, sparc 143
220 #ifdef __ia64__
221 #define SYS_gettid 1105
222 #else
223 #ifdef __i386__
224 #define SYS_gettid 224
225 #else
226 #ifdef __amd64__
227 #define SYS_gettid 186
228 #else
229 #ifdef __sparc__
230 #define SYS_gettid 143
231 #else
232 #error define gettid for the arch
233 #endif
234 #endif
235 #endif
236 #endif
237 #endif
239 // Cpu architecture string
240 static char cpu_arch[] = HOTSPOT_LIB_ARCH;
242 // pid_t gettid()
243 //
244 // Returns the kernel thread id of the currently running thread. Kernel
245 // thread id is used to access /proc.
246 //
247 // (Note that getpid() on LinuxThreads returns kernel thread id too; but
248 // on NPTL, it returns the same pid for all threads, as required by POSIX.)
249 //
250 pid_t os::Linux::gettid() {
251 int rslt = syscall(SYS_gettid);
252 if (rslt == -1) {
253 // old kernel, no NPTL support
254 return getpid();
255 } else {
256 return (pid_t)rslt;
257 }
258 }
260 // Most versions of linux have a bug where the number of processors are
261 // determined by looking at the /proc file system. In a chroot environment,
262 // the system call returns 1. This causes the VM to act as if it is
263 // a single processor and elide locking (see is_MP() call).
264 static bool unsafe_chroot_detected = false;
265 static const char *unstable_chroot_error = "/proc file system not found.\n"
266 "Java may be unstable running multithreaded in a chroot "
267 "environment on Linux when /proc filesystem is not mounted.";
269 void os::Linux::initialize_system_info() {
270 set_processor_count(sysconf(_SC_NPROCESSORS_CONF));
271 if (processor_count() == 1) {
272 pid_t pid = os::Linux::gettid();
273 char fname[32];
274 jio_snprintf(fname, sizeof(fname), "/proc/%d", pid);
275 FILE *fp = fopen(fname, "r");
276 if (fp == NULL) {
277 unsafe_chroot_detected = true;
278 } else {
279 fclose(fp);
280 }
281 }
282 _physical_memory = (julong)sysconf(_SC_PHYS_PAGES) * (julong)sysconf(_SC_PAGESIZE);
283 assert(processor_count() > 0, "linux error");
284 }
286 void os::init_system_properties_values() {
287 // The next steps are taken in the product version:
288 //
289 // Obtain the JAVA_HOME value from the location of libjvm.so.
290 // This library should be located at:
291 // <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm.so.
292 //
293 // If "/jre/lib/" appears at the right place in the path, then we
294 // assume libjvm.so is installed in a JDK and we use this path.
295 //
296 // Otherwise exit with message: "Could not create the Java virtual machine."
297 //
298 // The following extra steps are taken in the debugging version:
299 //
300 // If "/jre/lib/" does NOT appear at the right place in the path
301 // instead of exit check for $JAVA_HOME environment variable.
302 //
303 // If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>,
304 // then we append a fake suffix "hotspot/libjvm.so" to this path so
305 // it looks like libjvm.so is installed there
306 // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm.so.
307 //
308 // Otherwise exit.
309 //
310 // Important note: if the location of libjvm.so changes this
311 // code needs to be changed accordingly.
313 // See ld(1):
314 // The linker uses the following search paths to locate required
315 // shared libraries:
316 // 1: ...
317 // ...
318 // 7: The default directories, normally /lib and /usr/lib.
319 #if defined(AMD64) || defined(_LP64) && (defined(SPARC) || defined(PPC) || defined(S390))
320 #define DEFAULT_LIBPATH "/usr/lib64:/lib64:/lib:/usr/lib"
321 #else
322 #define DEFAULT_LIBPATH "/lib:/usr/lib"
323 #endif
325 // Base path of extensions installed on the system.
326 #define SYS_EXT_DIR "/usr/java/packages"
327 #define EXTENSIONS_DIR "/lib/ext"
328 #define ENDORSED_DIR "/lib/endorsed"
330 // Buffer that fits several sprintfs.
331 // Note that the space for the colon and the trailing null are provided
332 // by the nulls included by the sizeof operator.
333 const size_t bufsize =
334 MAX3((size_t)MAXPATHLEN, // For dll_dir & friends.
335 (size_t)MAXPATHLEN + sizeof(EXTENSIONS_DIR) + sizeof(SYS_EXT_DIR) + sizeof(EXTENSIONS_DIR), // extensions dir
336 (size_t)MAXPATHLEN + sizeof(ENDORSED_DIR)); // endorsed dir
337 char *buf = (char *)NEW_C_HEAP_ARRAY(char, bufsize, mtInternal);
339 // sysclasspath, java_home, dll_dir
340 {
341 char *pslash;
342 os::jvm_path(buf, bufsize);
344 // Found the full path to libjvm.so.
345 // Now cut the path to <java_home>/jre if we can.
346 *(strrchr(buf, '/')) = '\0'; // Get rid of /libjvm.so.
347 pslash = strrchr(buf, '/');
348 if (pslash != NULL) {
349 *pslash = '\0'; // Get rid of /{client|server|hotspot}.
350 }
351 Arguments::set_dll_dir(buf);
353 if (pslash != NULL) {
354 pslash = strrchr(buf, '/');
355 if (pslash != NULL) {
356 *pslash = '\0'; // Get rid of /<arch>.
357 pslash = strrchr(buf, '/');
358 if (pslash != NULL) {
359 *pslash = '\0'; // Get rid of /lib.
360 }
361 }
362 }
363 Arguments::set_java_home(buf);
364 set_boot_path('/', ':');
365 }
367 // Where to look for native libraries.
368 //
369 // Note: Due to a legacy implementation, most of the library path
370 // is set in the launcher. This was to accomodate linking restrictions
371 // on legacy Linux implementations (which are no longer supported).
372 // Eventually, all the library path setting will be done here.
373 //
374 // However, to prevent the proliferation of improperly built native
375 // libraries, the new path component /usr/java/packages is added here.
376 // Eventually, all the library path setting will be done here.
377 {
378 // Get the user setting of LD_LIBRARY_PATH, and prepended it. It
379 // should always exist (until the legacy problem cited above is
380 // addressed).
381 const char *v = ::getenv("LD_LIBRARY_PATH");
382 const char *v_colon = ":";
383 if (v == NULL) { v = ""; v_colon = ""; }
384 // That's +1 for the colon and +1 for the trailing '\0'.
385 char *ld_library_path = (char *)NEW_C_HEAP_ARRAY(char,
386 strlen(v) + 1 +
387 sizeof(SYS_EXT_DIR) + sizeof("/lib/") + strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH) + 1,
388 mtInternal);
389 sprintf(ld_library_path, "%s%s" SYS_EXT_DIR "/lib/%s:" DEFAULT_LIBPATH, v, v_colon, cpu_arch);
390 Arguments::set_library_path(ld_library_path);
391 FREE_C_HEAP_ARRAY(char, ld_library_path, mtInternal);
392 }
394 // Extensions directories.
395 sprintf(buf, "%s" EXTENSIONS_DIR ":" SYS_EXT_DIR EXTENSIONS_DIR, Arguments::get_java_home());
396 Arguments::set_ext_dirs(buf);
398 // Endorsed standards default directory.
399 sprintf(buf, "%s" ENDORSED_DIR, Arguments::get_java_home());
400 Arguments::set_endorsed_dirs(buf);
402 FREE_C_HEAP_ARRAY(char, buf, mtInternal);
404 #undef DEFAULT_LIBPATH
405 #undef SYS_EXT_DIR
406 #undef EXTENSIONS_DIR
407 #undef ENDORSED_DIR
408 }
410 ////////////////////////////////////////////////////////////////////////////////
411 // breakpoint support
413 void os::breakpoint() {
414 BREAKPOINT;
415 }
417 extern "C" void breakpoint() {
418 // use debugger to set breakpoint here
419 }
421 ////////////////////////////////////////////////////////////////////////////////
422 // signal support
424 debug_only(static bool signal_sets_initialized = false);
425 static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs;
427 bool os::Linux::is_sig_ignored(int sig) {
428 struct sigaction oact;
429 sigaction(sig, (struct sigaction*)NULL, &oact);
430 void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*, oact.sa_sigaction)
431 : CAST_FROM_FN_PTR(void*, oact.sa_handler);
432 if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN))
433 return true;
434 else
435 return false;
436 }
438 void os::Linux::signal_sets_init() {
439 // Should also have an assertion stating we are still single-threaded.
440 assert(!signal_sets_initialized, "Already initialized");
441 // Fill in signals that are necessarily unblocked for all threads in
442 // the VM. Currently, we unblock the following signals:
443 // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden
444 // by -Xrs (=ReduceSignalUsage));
445 // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all
446 // other threads. The "ReduceSignalUsage" boolean tells us not to alter
447 // the dispositions or masks wrt these signals.
448 // Programs embedding the VM that want to use the above signals for their
449 // own purposes must, at this time, use the "-Xrs" option to prevent
450 // interference with shutdown hooks and BREAK_SIGNAL thread dumping.
451 // (See bug 4345157, and other related bugs).
452 // In reality, though, unblocking these signals is really a nop, since
453 // these signals are not blocked by default.
454 sigemptyset(&unblocked_sigs);
455 sigemptyset(&allowdebug_blocked_sigs);
456 sigaddset(&unblocked_sigs, SIGILL);
457 sigaddset(&unblocked_sigs, SIGSEGV);
458 sigaddset(&unblocked_sigs, SIGBUS);
459 sigaddset(&unblocked_sigs, SIGFPE);
460 #if defined(PPC64)
461 sigaddset(&unblocked_sigs, SIGTRAP);
462 #endif
463 sigaddset(&unblocked_sigs, SR_signum);
465 if (!ReduceSignalUsage) {
466 if (!os::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) {
467 sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL);
468 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL);
469 }
470 if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) {
471 sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL);
472 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL);
473 }
474 if (!os::Linux::is_sig_ignored(SHUTDOWN3_SIGNAL)) {
475 sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL);
476 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN3_SIGNAL);
477 }
478 }
479 // Fill in signals that are blocked by all but the VM thread.
480 sigemptyset(&vm_sigs);
481 if (!ReduceSignalUsage)
482 sigaddset(&vm_sigs, BREAK_SIGNAL);
483 debug_only(signal_sets_initialized = true);
485 }
487 // These are signals that are unblocked while a thread is running Java.
488 // (For some reason, they get blocked by default.)
489 sigset_t* os::Linux::unblocked_signals() {
490 assert(signal_sets_initialized, "Not initialized");
491 return &unblocked_sigs;
492 }
494 // These are the signals that are blocked while a (non-VM) thread is
495 // running Java. Only the VM thread handles these signals.
496 sigset_t* os::Linux::vm_signals() {
497 assert(signal_sets_initialized, "Not initialized");
498 return &vm_sigs;
499 }
501 // These are signals that are blocked during cond_wait to allow debugger in
502 sigset_t* os::Linux::allowdebug_blocked_signals() {
503 assert(signal_sets_initialized, "Not initialized");
504 return &allowdebug_blocked_sigs;
505 }
507 void os::Linux::hotspot_sigmask(Thread* thread) {
509 //Save caller's signal mask before setting VM signal mask
510 sigset_t caller_sigmask;
511 pthread_sigmask(SIG_BLOCK, NULL, &caller_sigmask);
513 OSThread* osthread = thread->osthread();
514 osthread->set_caller_sigmask(caller_sigmask);
516 pthread_sigmask(SIG_UNBLOCK, os::Linux::unblocked_signals(), NULL);
518 if (!ReduceSignalUsage) {
519 if (thread->is_VM_thread()) {
520 // Only the VM thread handles BREAK_SIGNAL ...
521 pthread_sigmask(SIG_UNBLOCK, vm_signals(), NULL);
522 } else {
523 // ... all other threads block BREAK_SIGNAL
524 pthread_sigmask(SIG_BLOCK, vm_signals(), NULL);
525 }
526 }
527 }
529 //////////////////////////////////////////////////////////////////////////////
530 // detecting pthread library
532 void os::Linux::libpthread_init() {
533 // Save glibc and pthread version strings. Note that _CS_GNU_LIBC_VERSION
534 // and _CS_GNU_LIBPTHREAD_VERSION are supported in glibc >= 2.3.2. Use a
535 // generic name for earlier versions.
536 // Define macros here so we can build HotSpot on old systems.
537 # ifndef _CS_GNU_LIBC_VERSION
538 # define _CS_GNU_LIBC_VERSION 2
539 # endif
540 # ifndef _CS_GNU_LIBPTHREAD_VERSION
541 # define _CS_GNU_LIBPTHREAD_VERSION 3
542 # endif
544 size_t n = confstr(_CS_GNU_LIBC_VERSION, NULL, 0);
545 if (n > 0) {
546 char *str = (char *)malloc(n, mtInternal);
547 confstr(_CS_GNU_LIBC_VERSION, str, n);
548 os::Linux::set_glibc_version(str);
549 } else {
550 // _CS_GNU_LIBC_VERSION is not supported, try gnu_get_libc_version()
551 static char _gnu_libc_version[32];
552 jio_snprintf(_gnu_libc_version, sizeof(_gnu_libc_version),
553 "glibc %s %s", gnu_get_libc_version(), gnu_get_libc_release());
554 os::Linux::set_glibc_version(_gnu_libc_version);
555 }
557 n = confstr(_CS_GNU_LIBPTHREAD_VERSION, NULL, 0);
558 if (n > 0) {
559 char *str = (char *)malloc(n, mtInternal);
560 confstr(_CS_GNU_LIBPTHREAD_VERSION, str, n);
561 // Vanilla RH-9 (glibc 2.3.2) has a bug that confstr() always tells
562 // us "NPTL-0.29" even we are running with LinuxThreads. Check if this
563 // is the case. LinuxThreads has a hard limit on max number of threads.
564 // So sysconf(_SC_THREAD_THREADS_MAX) will return a positive value.
565 // On the other hand, NPTL does not have such a limit, sysconf()
566 // will return -1 and errno is not changed. Check if it is really NPTL.
567 if (strcmp(os::Linux::glibc_version(), "glibc 2.3.2") == 0 &&
568 strstr(str, "NPTL") &&
569 sysconf(_SC_THREAD_THREADS_MAX) > 0) {
570 free(str);
571 os::Linux::set_libpthread_version("linuxthreads");
572 } else {
573 os::Linux::set_libpthread_version(str);
574 }
575 } else {
576 // glibc before 2.3.2 only has LinuxThreads.
577 os::Linux::set_libpthread_version("linuxthreads");
578 }
580 if (strstr(libpthread_version(), "NPTL")) {
581 os::Linux::set_is_NPTL();
582 } else {
583 os::Linux::set_is_LinuxThreads();
584 }
586 // LinuxThreads have two flavors: floating-stack mode, which allows variable
587 // stack size; and fixed-stack mode. NPTL is always floating-stack.
588 if (os::Linux::is_NPTL() || os::Linux::supports_variable_stack_size()) {
589 os::Linux::set_is_floating_stack();
590 }
591 }
593 /////////////////////////////////////////////////////////////////////////////
594 // thread stack
596 // Force Linux kernel to expand current thread stack. If "bottom" is close
597 // to the stack guard, caller should block all signals.
598 //
599 // MAP_GROWSDOWN:
600 // A special mmap() flag that is used to implement thread stacks. It tells
601 // kernel that the memory region should extend downwards when needed. This
602 // allows early versions of LinuxThreads to only mmap the first few pages
603 // when creating a new thread. Linux kernel will automatically expand thread
604 // stack as needed (on page faults).
605 //
606 // However, because the memory region of a MAP_GROWSDOWN stack can grow on
607 // demand, if a page fault happens outside an already mapped MAP_GROWSDOWN
608 // region, it's hard to tell if the fault is due to a legitimate stack
609 // access or because of reading/writing non-exist memory (e.g. buffer
610 // overrun). As a rule, if the fault happens below current stack pointer,
611 // Linux kernel does not expand stack, instead a SIGSEGV is sent to the
612 // application (see Linux kernel fault.c).
613 //
614 // This Linux feature can cause SIGSEGV when VM bangs thread stack for
615 // stack overflow detection.
616 //
617 // Newer version of LinuxThreads (since glibc-2.2, or, RH-7.x) and NPTL do
618 // not use this flag. However, the stack of initial thread is not created
619 // by pthread, it is still MAP_GROWSDOWN. Also it's possible (though
620 // unlikely) that user code can create a thread with MAP_GROWSDOWN stack
621 // and then attach the thread to JVM.
622 //
623 // To get around the problem and allow stack banging on Linux, we need to
624 // manually expand thread stack after receiving the SIGSEGV.
625 //
626 // There are two ways to expand thread stack to address "bottom", we used
627 // both of them in JVM before 1.5:
628 // 1. adjust stack pointer first so that it is below "bottom", and then
629 // touch "bottom"
630 // 2. mmap() the page in question
631 //
632 // Now alternate signal stack is gone, it's harder to use 2. For instance,
633 // if current sp is already near the lower end of page 101, and we need to
634 // call mmap() to map page 100, it is possible that part of the mmap() frame
635 // will be placed in page 100. When page 100 is mapped, it is zero-filled.
636 // That will destroy the mmap() frame and cause VM to crash.
637 //
638 // The following code works by adjusting sp first, then accessing the "bottom"
639 // page to force a page fault. Linux kernel will then automatically expand the
640 // stack mapping.
641 //
642 // _expand_stack_to() assumes its frame size is less than page size, which
643 // should always be true if the function is not inlined.
645 #if __GNUC__ < 3 // gcc 2.x does not support noinline attribute
646 #define NOINLINE
647 #else
648 #define NOINLINE __attribute__ ((noinline))
649 #endif
651 static void _expand_stack_to(address bottom) NOINLINE;
653 static void _expand_stack_to(address bottom) {
654 address sp;
655 size_t size;
656 volatile char *p;
658 // Adjust bottom to point to the largest address within the same page, it
659 // gives us a one-page buffer if alloca() allocates slightly more memory.
660 bottom = (address)align_size_down((uintptr_t)bottom, os::Linux::page_size());
661 bottom += os::Linux::page_size() - 1;
663 // sp might be slightly above current stack pointer; if that's the case, we
664 // will alloca() a little more space than necessary, which is OK. Don't use
665 // os::current_stack_pointer(), as its result can be slightly below current
666 // stack pointer, causing us to not alloca enough to reach "bottom".
667 sp = (address)&sp;
669 if (sp > bottom) {
670 size = sp - bottom;
671 p = (volatile char *)alloca(size);
672 assert(p != NULL && p <= (volatile char *)bottom, "alloca problem?");
673 p[0] = '\0';
674 }
675 }
677 bool os::Linux::manually_expand_stack(JavaThread * t, address addr) {
678 assert(t!=NULL, "just checking");
679 assert(t->osthread()->expanding_stack(), "expand should be set");
680 assert(t->stack_base() != NULL, "stack_base was not initialized");
682 if (addr < t->stack_base() && addr >= t->stack_yellow_zone_base()) {
683 sigset_t mask_all, old_sigset;
684 sigfillset(&mask_all);
685 pthread_sigmask(SIG_SETMASK, &mask_all, &old_sigset);
686 _expand_stack_to(addr);
687 pthread_sigmask(SIG_SETMASK, &old_sigset, NULL);
688 return true;
689 }
690 return false;
691 }
693 //////////////////////////////////////////////////////////////////////////////
694 // create new thread
696 static address highest_vm_reserved_address();
698 // check if it's safe to start a new thread
699 static bool _thread_safety_check(Thread* thread) {
700 if (os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack()) {
701 // Fixed stack LinuxThreads (SuSE Linux/x86, and some versions of Redhat)
702 // Heap is mmap'ed at lower end of memory space. Thread stacks are
703 // allocated (MAP_FIXED) from high address space. Every thread stack
704 // occupies a fixed size slot (usually 2Mbytes, but user can change
705 // it to other values if they rebuild LinuxThreads).
706 //
707 // Problem with MAP_FIXED is that mmap() can still succeed even part of
708 // the memory region has already been mmap'ed. That means if we have too
709 // many threads and/or very large heap, eventually thread stack will
710 // collide with heap.
711 //
712 // Here we try to prevent heap/stack collision by comparing current
713 // stack bottom with the highest address that has been mmap'ed by JVM
714 // plus a safety margin for memory maps created by native code.
715 //
716 // This feature can be disabled by setting ThreadSafetyMargin to 0
717 //
718 if (ThreadSafetyMargin > 0) {
719 address stack_bottom = os::current_stack_base() - os::current_stack_size();
721 // not safe if our stack extends below the safety margin
722 return stack_bottom - ThreadSafetyMargin >= highest_vm_reserved_address();
723 } else {
724 return true;
725 }
726 } else {
727 // Floating stack LinuxThreads or NPTL:
728 // Unlike fixed stack LinuxThreads, thread stacks are not MAP_FIXED. When
729 // there's not enough space left, pthread_create() will fail. If we come
730 // here, that means enough space has been reserved for stack.
731 return true;
732 }
733 }
735 // Thread start routine for all newly created threads
736 static void *java_start(Thread *thread) {
737 // Try to randomize the cache line index of hot stack frames.
738 // This helps when threads of the same stack traces evict each other's
739 // cache lines. The threads can be either from the same JVM instance, or
740 // from different JVM instances. The benefit is especially true for
741 // processors with hyperthreading technology.
742 static int counter = 0;
743 int pid = os::current_process_id();
744 alloca(((pid ^ counter++) & 7) * 128);
746 ThreadLocalStorage::set_thread(thread);
748 OSThread* osthread = thread->osthread();
749 Monitor* sync = osthread->startThread_lock();
751 // non floating stack LinuxThreads needs extra check, see above
752 if (!_thread_safety_check(thread)) {
753 // notify parent thread
754 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
755 osthread->set_state(ZOMBIE);
756 sync->notify_all();
757 return NULL;
758 }
760 // thread_id is kernel thread id (similar to Solaris LWP id)
761 osthread->set_thread_id(os::Linux::gettid());
763 if (UseNUMA) {
764 int lgrp_id = os::numa_get_group_id();
765 if (lgrp_id != -1) {
766 thread->set_lgrp_id(lgrp_id);
767 }
768 }
769 // initialize signal mask for this thread
770 os::Linux::hotspot_sigmask(thread);
772 // initialize floating point control register
773 os::Linux::init_thread_fpu_state();
775 // handshaking with parent thread
776 {
777 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
779 // notify parent thread
780 osthread->set_state(INITIALIZED);
781 sync->notify_all();
783 // wait until os::start_thread()
784 while (osthread->get_state() == INITIALIZED) {
785 sync->wait(Mutex::_no_safepoint_check_flag);
786 }
787 }
789 // call one more level start routine
790 thread->run();
792 return 0;
793 }
795 bool os::create_thread(Thread* thread, ThreadType thr_type, size_t stack_size) {
796 assert(thread->osthread() == NULL, "caller responsible");
798 // Allocate the OSThread object
799 OSThread* osthread = new OSThread(NULL, NULL);
800 if (osthread == NULL) {
801 return false;
802 }
804 // set the correct thread state
805 osthread->set_thread_type(thr_type);
807 // Initial state is ALLOCATED but not INITIALIZED
808 osthread->set_state(ALLOCATED);
810 thread->set_osthread(osthread);
812 // init thread attributes
813 pthread_attr_t attr;
814 pthread_attr_init(&attr);
815 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
817 // stack size
818 if (os::Linux::supports_variable_stack_size()) {
819 // calculate stack size if it's not specified by caller
820 if (stack_size == 0) {
821 stack_size = os::Linux::default_stack_size(thr_type);
823 switch (thr_type) {
824 case os::java_thread:
825 // Java threads use ThreadStackSize which default value can be
826 // changed with the flag -Xss
827 assert (JavaThread::stack_size_at_create() > 0, "this should be set");
828 stack_size = JavaThread::stack_size_at_create();
829 break;
830 case os::compiler_thread:
831 if (CompilerThreadStackSize > 0) {
832 stack_size = (size_t)(CompilerThreadStackSize * K);
833 break;
834 } // else fall through:
835 // use VMThreadStackSize if CompilerThreadStackSize is not defined
836 case os::vm_thread:
837 case os::pgc_thread:
838 case os::cgc_thread:
839 case os::watcher_thread:
840 if (VMThreadStackSize > 0) stack_size = (size_t)(VMThreadStackSize * K);
841 break;
842 }
843 }
845 stack_size = MAX2(stack_size, os::Linux::min_stack_allowed);
846 pthread_attr_setstacksize(&attr, stack_size);
847 } else {
848 // let pthread_create() pick the default value.
849 }
851 // glibc guard page
852 pthread_attr_setguardsize(&attr, os::Linux::default_guard_size(thr_type));
854 ThreadState state;
856 {
857 // Serialize thread creation if we are running with fixed stack LinuxThreads
858 bool lock = os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack();
859 if (lock) {
860 os::Linux::createThread_lock()->lock_without_safepoint_check();
861 }
863 pthread_t tid;
864 int ret = pthread_create(&tid, &attr, (void* (*)(void*)) java_start, thread);
866 pthread_attr_destroy(&attr);
868 if (ret != 0) {
869 if (PrintMiscellaneous && (Verbose || WizardMode)) {
870 perror("pthread_create()");
871 }
872 // Need to clean up stuff we've allocated so far
873 thread->set_osthread(NULL);
874 delete osthread;
875 if (lock) os::Linux::createThread_lock()->unlock();
876 return false;
877 }
879 // Store pthread info into the OSThread
880 osthread->set_pthread_id(tid);
882 // Wait until child thread is either initialized or aborted
883 {
884 Monitor* sync_with_child = osthread->startThread_lock();
885 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
886 while ((state = osthread->get_state()) == ALLOCATED) {
887 sync_with_child->wait(Mutex::_no_safepoint_check_flag);
888 }
889 }
891 if (lock) {
892 os::Linux::createThread_lock()->unlock();
893 }
894 }
896 // Aborted due to thread limit being reached
897 if (state == ZOMBIE) {
898 thread->set_osthread(NULL);
899 delete osthread;
900 return false;
901 }
903 // The thread is returned suspended (in state INITIALIZED),
904 // and is started higher up in the call chain
905 assert(state == INITIALIZED, "race condition");
906 return true;
907 }
909 /////////////////////////////////////////////////////////////////////////////
910 // attach existing thread
912 // bootstrap the main thread
913 bool os::create_main_thread(JavaThread* thread) {
914 assert(os::Linux::_main_thread == pthread_self(), "should be called inside main thread");
915 return create_attached_thread(thread);
916 }
918 bool os::create_attached_thread(JavaThread* thread) {
919 #ifdef ASSERT
920 thread->verify_not_published();
921 #endif
923 // Allocate the OSThread object
924 OSThread* osthread = new OSThread(NULL, NULL);
926 if (osthread == NULL) {
927 return false;
928 }
930 // Store pthread info into the OSThread
931 osthread->set_thread_id(os::Linux::gettid());
932 osthread->set_pthread_id(::pthread_self());
934 // initialize floating point control register
935 os::Linux::init_thread_fpu_state();
937 // Initial thread state is RUNNABLE
938 osthread->set_state(RUNNABLE);
940 thread->set_osthread(osthread);
942 if (UseNUMA) {
943 int lgrp_id = os::numa_get_group_id();
944 if (lgrp_id != -1) {
945 thread->set_lgrp_id(lgrp_id);
946 }
947 }
949 if (os::Linux::is_initial_thread()) {
950 // If current thread is initial thread, its stack is mapped on demand,
951 // see notes about MAP_GROWSDOWN. Here we try to force kernel to map
952 // the entire stack region to avoid SEGV in stack banging.
953 // It is also useful to get around the heap-stack-gap problem on SuSE
954 // kernel (see 4821821 for details). We first expand stack to the top
955 // of yellow zone, then enable stack yellow zone (order is significant,
956 // enabling yellow zone first will crash JVM on SuSE Linux), so there
957 // is no gap between the last two virtual memory regions.
959 JavaThread *jt = (JavaThread *)thread;
960 address addr = jt->stack_yellow_zone_base();
961 assert(addr != NULL, "initialization problem?");
962 assert(jt->stack_available(addr) > 0, "stack guard should not be enabled");
964 osthread->set_expanding_stack();
965 os::Linux::manually_expand_stack(jt, addr);
966 osthread->clear_expanding_stack();
967 }
969 // initialize signal mask for this thread
970 // and save the caller's signal mask
971 os::Linux::hotspot_sigmask(thread);
973 return true;
974 }
976 void os::pd_start_thread(Thread* thread) {
977 OSThread * osthread = thread->osthread();
978 assert(osthread->get_state() != INITIALIZED, "just checking");
979 Monitor* sync_with_child = osthread->startThread_lock();
980 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
981 sync_with_child->notify();
983 #ifdef MIPS64
984 //To be accessed in NativeGeneralJump::patch_verified_entry()
985 if (thread->is_Java_thread())
986 {
987 ((JavaThread*)thread)->set_handle_wrong_method_stub(SharedRuntime::get_handle_wrong_method_stub());
988 }
989 #endif
990 }
992 // Free Linux resources related to the OSThread
993 void os::free_thread(OSThread* osthread) {
994 assert(osthread != NULL, "osthread not set");
996 if (Thread::current()->osthread() == osthread) {
997 // Restore caller's signal mask
998 sigset_t sigmask = osthread->caller_sigmask();
999 pthread_sigmask(SIG_SETMASK, &sigmask, NULL);
1000 }
1002 delete osthread;
1003 }
1005 //////////////////////////////////////////////////////////////////////////////
1006 // thread local storage
1008 // Restore the thread pointer if the destructor is called. This is in case
1009 // someone from JNI code sets up a destructor with pthread_key_create to run
1010 // detachCurrentThread on thread death. Unless we restore the thread pointer we
1011 // will hang or crash. When detachCurrentThread is called the key will be set
1012 // to null and we will not be called again. If detachCurrentThread is never
1013 // called we could loop forever depending on the pthread implementation.
1014 static void restore_thread_pointer(void* p) {
1015 Thread* thread = (Thread*) p;
1016 os::thread_local_storage_at_put(ThreadLocalStorage::thread_index(), thread);
1017 }
1019 int os::allocate_thread_local_storage() {
1020 pthread_key_t key;
1021 int rslt = pthread_key_create(&key, restore_thread_pointer);
1022 assert(rslt == 0, "cannot allocate thread local storage");
1023 return (int)key;
1024 }
1026 // Note: This is currently not used by VM, as we don't destroy TLS key
1027 // on VM exit.
1028 void os::free_thread_local_storage(int index) {
1029 int rslt = pthread_key_delete((pthread_key_t)index);
1030 assert(rslt == 0, "invalid index");
1031 }
1033 void os::thread_local_storage_at_put(int index, void* value) {
1034 int rslt = pthread_setspecific((pthread_key_t)index, value);
1035 assert(rslt == 0, "pthread_setspecific failed");
1036 }
1038 extern "C" Thread* get_thread() {
1039 return ThreadLocalStorage::thread();
1040 }
1042 //////////////////////////////////////////////////////////////////////////////
1043 // initial thread
1045 // Check if current thread is the initial thread, similar to Solaris thr_main.
1046 bool os::Linux::is_initial_thread(void) {
1047 char dummy;
1048 // If called before init complete, thread stack bottom will be null.
1049 // Can be called if fatal error occurs before initialization.
1050 if (initial_thread_stack_bottom() == NULL) return false;
1051 assert(initial_thread_stack_bottom() != NULL &&
1052 initial_thread_stack_size() != 0,
1053 "os::init did not locate initial thread's stack region");
1054 if ((address)&dummy >= initial_thread_stack_bottom() &&
1055 (address)&dummy < initial_thread_stack_bottom() + initial_thread_stack_size())
1056 return true;
1057 else return false;
1058 }
1060 // Find the virtual memory area that contains addr
1061 static bool find_vma(address addr, address* vma_low, address* vma_high) {
1062 FILE *fp = fopen("/proc/self/maps", "r");
1063 if (fp) {
1064 address low, high;
1065 while (!feof(fp)) {
1066 if (fscanf(fp, "%p-%p", &low, &high) == 2) {
1067 if (low <= addr && addr < high) {
1068 if (vma_low) *vma_low = low;
1069 if (vma_high) *vma_high = high;
1070 fclose (fp);
1071 return true;
1072 }
1073 }
1074 for (;;) {
1075 int ch = fgetc(fp);
1076 if (ch == EOF || ch == (int)'\n') break;
1077 }
1078 }
1079 fclose(fp);
1080 }
1081 return false;
1082 }
1084 // Locate initial thread stack. This special handling of initial thread stack
1085 // is needed because pthread_getattr_np() on most (all?) Linux distros returns
1086 // bogus value for the primordial process thread. While the launcher has created
1087 // the VM in a new thread since JDK 6, we still have to allow for the use of the
1088 // JNI invocation API from a primordial thread.
1089 void os::Linux::capture_initial_stack(size_t max_size) {
1091 // max_size is either 0 (which means accept OS default for thread stacks) or
1092 // a user-specified value known to be at least the minimum needed. If we
1093 // are actually on the primordial thread we can make it appear that we have a
1094 // smaller max_size stack by inserting the guard pages at that location. But we
1095 // cannot do anything to emulate a larger stack than what has been provided by
1096 // the OS or threading library. In fact if we try to use a stack greater than
1097 // what is set by rlimit then we will crash the hosting process.
1099 // Maximum stack size is the easy part, get it from RLIMIT_STACK.
1100 // If this is "unlimited" then it will be a huge value.
1101 struct rlimit rlim;
1102 getrlimit(RLIMIT_STACK, &rlim);
1103 size_t stack_size = rlim.rlim_cur;
1105 // 6308388: a bug in ld.so will relocate its own .data section to the
1106 // lower end of primordial stack; reduce ulimit -s value a little bit
1107 // so we won't install guard page on ld.so's data section.
1108 stack_size -= 2 * page_size();
1110 // Try to figure out where the stack base (top) is. This is harder.
1111 //
1112 // When an application is started, glibc saves the initial stack pointer in
1113 // a global variable "__libc_stack_end", which is then used by system
1114 // libraries. __libc_stack_end should be pretty close to stack top. The
1115 // variable is available since the very early days. However, because it is
1116 // a private interface, it could disappear in the future.
1117 //
1118 // Linux kernel saves start_stack information in /proc/<pid>/stat. Similar
1119 // to __libc_stack_end, it is very close to stack top, but isn't the real
1120 // stack top. Note that /proc may not exist if VM is running as a chroot
1121 // program, so reading /proc/<pid>/stat could fail. Also the contents of
1122 // /proc/<pid>/stat could change in the future (though unlikely).
1123 //
1124 // We try __libc_stack_end first. If that doesn't work, look for
1125 // /proc/<pid>/stat. If neither of them works, we use current stack pointer
1126 // as a hint, which should work well in most cases.
1128 uintptr_t stack_start;
1130 // try __libc_stack_end first
1131 uintptr_t *p = (uintptr_t *)dlsym(RTLD_DEFAULT, "__libc_stack_end");
1132 if (p && *p) {
1133 stack_start = *p;
1134 } else {
1135 // see if we can get the start_stack field from /proc/self/stat
1136 FILE *fp;
1137 int pid;
1138 char state;
1139 int ppid;
1140 int pgrp;
1141 int session;
1142 int nr;
1143 int tpgrp;
1144 unsigned long flags;
1145 unsigned long minflt;
1146 unsigned long cminflt;
1147 unsigned long majflt;
1148 unsigned long cmajflt;
1149 unsigned long utime;
1150 unsigned long stime;
1151 long cutime;
1152 long cstime;
1153 long prio;
1154 long nice;
1155 long junk;
1156 long it_real;
1157 uintptr_t start;
1158 uintptr_t vsize;
1159 intptr_t rss;
1160 uintptr_t rsslim;
1161 uintptr_t scodes;
1162 uintptr_t ecode;
1163 int i;
1165 // Figure what the primordial thread stack base is. Code is inspired
1166 // by email from Hans Boehm. /proc/self/stat begins with current pid,
1167 // followed by command name surrounded by parentheses, state, etc.
1168 char stat[2048];
1169 int statlen;
1171 fp = fopen("/proc/self/stat", "r");
1172 if (fp) {
1173 statlen = fread(stat, 1, 2047, fp);
1174 stat[statlen] = '\0';
1175 fclose(fp);
1177 // Skip pid and the command string. Note that we could be dealing with
1178 // weird command names, e.g. user could decide to rename java launcher
1179 // to "java 1.4.2 :)", then the stat file would look like
1180 // 1234 (java 1.4.2 :)) R ... ...
1181 // We don't really need to know the command string, just find the last
1182 // occurrence of ")" and then start parsing from there. See bug 4726580.
1183 char * s = strrchr(stat, ')');
1185 i = 0;
1186 if (s) {
1187 // Skip blank chars
1188 do s++; while (isspace(*s));
1190 #define _UFM UINTX_FORMAT
1191 #define _DFM INTX_FORMAT
1193 /* 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 */
1194 /* 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 */
1195 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,
1196 &state, /* 3 %c */
1197 &ppid, /* 4 %d */
1198 &pgrp, /* 5 %d */
1199 &session, /* 6 %d */
1200 &nr, /* 7 %d */
1201 &tpgrp, /* 8 %d */
1202 &flags, /* 9 %lu */
1203 &minflt, /* 10 %lu */
1204 &cminflt, /* 11 %lu */
1205 &majflt, /* 12 %lu */
1206 &cmajflt, /* 13 %lu */
1207 &utime, /* 14 %lu */
1208 &stime, /* 15 %lu */
1209 &cutime, /* 16 %ld */
1210 &cstime, /* 17 %ld */
1211 &prio, /* 18 %ld */
1212 &nice, /* 19 %ld */
1213 &junk, /* 20 %ld */
1214 &it_real, /* 21 %ld */
1215 &start, /* 22 UINTX_FORMAT */
1216 &vsize, /* 23 UINTX_FORMAT */
1217 &rss, /* 24 INTX_FORMAT */
1218 &rsslim, /* 25 UINTX_FORMAT */
1219 &scodes, /* 26 UINTX_FORMAT */
1220 &ecode, /* 27 UINTX_FORMAT */
1221 &stack_start); /* 28 UINTX_FORMAT */
1222 }
1224 #undef _UFM
1225 #undef _DFM
1227 if (i != 28 - 2) {
1228 assert(false, "Bad conversion from /proc/self/stat");
1229 // product mode - assume we are the initial thread, good luck in the
1230 // embedded case.
1231 warning("Can't detect initial thread stack location - bad conversion");
1232 stack_start = (uintptr_t) &rlim;
1233 }
1234 } else {
1235 // For some reason we can't open /proc/self/stat (for example, running on
1236 // FreeBSD with a Linux emulator, or inside chroot), this should work for
1237 // most cases, so don't abort:
1238 warning("Can't detect initial thread stack location - no /proc/self/stat");
1239 stack_start = (uintptr_t) &rlim;
1240 }
1241 }
1243 // Now we have a pointer (stack_start) very close to the stack top, the
1244 // next thing to do is to figure out the exact location of stack top. We
1245 // can find out the virtual memory area that contains stack_start by
1246 // reading /proc/self/maps, it should be the last vma in /proc/self/maps,
1247 // and its upper limit is the real stack top. (again, this would fail if
1248 // running inside chroot, because /proc may not exist.)
1250 uintptr_t stack_top;
1251 address low, high;
1252 if (find_vma((address)stack_start, &low, &high)) {
1253 // success, "high" is the true stack top. (ignore "low", because initial
1254 // thread stack grows on demand, its real bottom is high - RLIMIT_STACK.)
1255 stack_top = (uintptr_t)high;
1256 } else {
1257 // failed, likely because /proc/self/maps does not exist
1258 warning("Can't detect initial thread stack location - find_vma failed");
1259 // best effort: stack_start is normally within a few pages below the real
1260 // stack top, use it as stack top, and reduce stack size so we won't put
1261 // guard page outside stack.
1262 stack_top = stack_start;
1263 stack_size -= 16 * page_size();
1264 }
1266 // stack_top could be partially down the page so align it
1267 stack_top = align_size_up(stack_top, page_size());
1269 // Allowed stack value is minimum of max_size and what we derived from rlimit
1270 if (max_size > 0) {
1271 _initial_thread_stack_size = MIN2(max_size, stack_size);
1272 } else {
1273 // Accept the rlimit max, but if stack is unlimited then it will be huge, so
1274 // clamp it at 8MB as we do on Solaris
1275 _initial_thread_stack_size = MIN2(stack_size, 8*M);
1276 }
1278 _initial_thread_stack_size = align_size_down(_initial_thread_stack_size, page_size());
1279 _initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size;
1280 assert(_initial_thread_stack_bottom < (address)stack_top, "overflow!");
1281 }
1283 ////////////////////////////////////////////////////////////////////////////////
1284 // time support
1286 // Time since start-up in seconds to a fine granularity.
1287 // Used by VMSelfDestructTimer and the MemProfiler.
1288 double os::elapsedTime() {
1290 return ((double)os::elapsed_counter()) / os::elapsed_frequency(); // nanosecond resolution
1291 }
1293 jlong os::elapsed_counter() {
1294 return javaTimeNanos() - initial_time_count;
1295 }
1297 jlong os::elapsed_frequency() {
1298 return NANOSECS_PER_SEC; // nanosecond resolution
1299 }
1301 bool os::supports_vtime() { return true; }
1302 bool os::enable_vtime() { return false; }
1303 bool os::vtime_enabled() { return false; }
1305 double os::elapsedVTime() {
1306 struct rusage usage;
1307 int retval = getrusage(RUSAGE_THREAD, &usage);
1308 if (retval == 0) {
1309 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);
1310 } else {
1311 // better than nothing, but not much
1312 return elapsedTime();
1313 }
1314 }
1316 jlong os::javaTimeMillis() {
1317 timeval time;
1318 int status = gettimeofday(&time, NULL);
1319 assert(status != -1, "linux error");
1320 return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000);
1321 }
1323 #ifndef CLOCK_MONOTONIC
1324 #define CLOCK_MONOTONIC (1)
1325 #endif
1327 void os::Linux::clock_init() {
1328 // we do dlopen's in this particular order due to bug in linux
1329 // dynamical loader (see 6348968) leading to crash on exit
1330 void* handle = dlopen("librt.so.1", RTLD_LAZY);
1331 if (handle == NULL) {
1332 handle = dlopen("librt.so", RTLD_LAZY);
1333 }
1335 if (handle) {
1336 int (*clock_getres_func)(clockid_t, struct timespec*) =
1337 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres");
1338 int (*clock_gettime_func)(clockid_t, struct timespec*) =
1339 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime");
1340 if (clock_getres_func && clock_gettime_func) {
1341 // See if monotonic clock is supported by the kernel. Note that some
1342 // early implementations simply return kernel jiffies (updated every
1343 // 1/100 or 1/1000 second). It would be bad to use such a low res clock
1344 // for nano time (though the monotonic property is still nice to have).
1345 // It's fixed in newer kernels, however clock_getres() still returns
1346 // 1/HZ. We check if clock_getres() works, but will ignore its reported
1347 // resolution for now. Hopefully as people move to new kernels, this
1348 // won't be a problem.
1349 struct timespec res;
1350 struct timespec tp;
1351 if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 &&
1352 clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) {
1353 // yes, monotonic clock is supported
1354 _clock_gettime = clock_gettime_func;
1355 return;
1356 } else {
1357 // close librt if there is no monotonic clock
1358 dlclose(handle);
1359 }
1360 }
1361 }
1362 warning("No monotonic clock was available - timed services may " \
1363 "be adversely affected if the time-of-day clock changes");
1364 }
1366 #ifndef SYS_clock_getres
1368 #if defined(IA32) || defined(AMD64)
1369 #define SYS_clock_getres IA32_ONLY(266) AMD64_ONLY(229)
1370 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y)
1371 #else
1372 #warning "SYS_clock_getres not defined for this platform, disabling fast_thread_cpu_time"
1373 #define sys_clock_getres(x,y) -1
1374 #endif
1376 #else
1377 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y)
1378 #endif
1380 void os::Linux::fast_thread_clock_init() {
1381 if (!UseLinuxPosixThreadCPUClocks) {
1382 return;
1383 }
1384 clockid_t clockid;
1385 struct timespec tp;
1386 int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) =
1387 (int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid");
1389 // Switch to using fast clocks for thread cpu time if
1390 // the sys_clock_getres() returns 0 error code.
1391 // Note, that some kernels may support the current thread
1392 // clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks
1393 // returned by the pthread_getcpuclockid().
1394 // If the fast Posix clocks are supported then the sys_clock_getres()
1395 // must return at least tp.tv_sec == 0 which means a resolution
1396 // better than 1 sec. This is extra check for reliability.
1398 if(pthread_getcpuclockid_func &&
1399 pthread_getcpuclockid_func(_main_thread, &clockid) == 0 &&
1400 sys_clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) {
1402 _supports_fast_thread_cpu_time = true;
1403 _pthread_getcpuclockid = pthread_getcpuclockid_func;
1404 }
1405 }
1407 jlong os::javaTimeNanos() {
1408 if (Linux::supports_monotonic_clock()) {
1409 struct timespec tp;
1410 int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp);
1411 assert(status == 0, "gettime error");
1412 jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec);
1413 return result;
1414 } else {
1415 timeval time;
1416 int status = gettimeofday(&time, NULL);
1417 assert(status != -1, "linux error");
1418 jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec);
1419 return 1000 * usecs;
1420 }
1421 }
1423 void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) {
1424 if (Linux::supports_monotonic_clock()) {
1425 info_ptr->max_value = ALL_64_BITS;
1427 // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past
1428 info_ptr->may_skip_backward = false; // not subject to resetting or drifting
1429 info_ptr->may_skip_forward = false; // not subject to resetting or drifting
1430 } else {
1431 // gettimeofday - based on time in seconds since the Epoch thus does not wrap
1432 info_ptr->max_value = ALL_64_BITS;
1434 // gettimeofday is a real time clock so it skips
1435 info_ptr->may_skip_backward = true;
1436 info_ptr->may_skip_forward = true;
1437 }
1439 info_ptr->kind = JVMTI_TIMER_ELAPSED; // elapsed not CPU time
1440 }
1442 // Return the real, user, and system times in seconds from an
1443 // arbitrary fixed point in the past.
1444 bool os::getTimesSecs(double* process_real_time,
1445 double* process_user_time,
1446 double* process_system_time) {
1447 struct tms ticks;
1448 clock_t real_ticks = times(&ticks);
1450 if (real_ticks == (clock_t) (-1)) {
1451 return false;
1452 } else {
1453 double ticks_per_second = (double) clock_tics_per_sec;
1454 *process_user_time = ((double) ticks.tms_utime) / ticks_per_second;
1455 *process_system_time = ((double) ticks.tms_stime) / ticks_per_second;
1456 *process_real_time = ((double) real_ticks) / ticks_per_second;
1458 return true;
1459 }
1460 }
1463 char * os::local_time_string(char *buf, size_t buflen) {
1464 struct tm t;
1465 time_t long_time;
1466 time(&long_time);
1467 localtime_r(&long_time, &t);
1468 jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d",
1469 t.tm_year + 1900, t.tm_mon + 1, t.tm_mday,
1470 t.tm_hour, t.tm_min, t.tm_sec);
1471 return buf;
1472 }
1474 struct tm* os::localtime_pd(const time_t* clock, struct tm* res) {
1475 return localtime_r(clock, res);
1476 }
1478 ////////////////////////////////////////////////////////////////////////////////
1479 // runtime exit support
1481 // Note: os::shutdown() might be called very early during initialization, or
1482 // called from signal handler. Before adding something to os::shutdown(), make
1483 // sure it is async-safe and can handle partially initialized VM.
1484 void os::shutdown() {
1486 // allow PerfMemory to attempt cleanup of any persistent resources
1487 perfMemory_exit();
1489 // needs to remove object in file system
1490 AttachListener::abort();
1492 // flush buffered output, finish log files
1493 ostream_abort();
1495 // Check for abort hook
1496 abort_hook_t abort_hook = Arguments::abort_hook();
1497 if (abort_hook != NULL) {
1498 abort_hook();
1499 }
1501 }
1503 // Note: os::abort() might be called very early during initialization, or
1504 // called from signal handler. Before adding something to os::abort(), make
1505 // sure it is async-safe and can handle partially initialized VM.
1506 void os::abort(bool dump_core) {
1507 os::shutdown();
1508 if (dump_core) {
1509 #ifndef PRODUCT
1510 fdStream out(defaultStream::output_fd());
1511 out.print_raw("Current thread is ");
1512 char buf[16];
1513 jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id());
1514 out.print_raw_cr(buf);
1515 out.print_raw_cr("Dumping core ...");
1516 #endif
1517 ::abort(); // dump core
1518 }
1520 ::exit(1);
1521 }
1523 // Die immediately, no exit hook, no abort hook, no cleanup.
1524 void os::die() {
1525 // _exit() on LinuxThreads only kills current thread
1526 ::abort();
1527 }
1530 // This method is a copy of JDK's sysGetLastErrorString
1531 // from src/solaris/hpi/src/system_md.c
1533 size_t os::lasterror(char *buf, size_t len) {
1535 if (errno == 0) return 0;
1537 const char *s = ::strerror(errno);
1538 size_t n = ::strlen(s);
1539 if (n >= len) {
1540 n = len - 1;
1541 }
1542 ::strncpy(buf, s, n);
1543 buf[n] = '\0';
1544 return n;
1545 }
1547 intx os::current_thread_id() { return (intx)pthread_self(); }
1548 int os::current_process_id() {
1550 // Under the old linux thread library, linux gives each thread
1551 // its own process id. Because of this each thread will return
1552 // a different pid if this method were to return the result
1553 // of getpid(2). Linux provides no api that returns the pid
1554 // of the launcher thread for the vm. This implementation
1555 // returns a unique pid, the pid of the launcher thread
1556 // that starts the vm 'process'.
1558 // Under the NPTL, getpid() returns the same pid as the
1559 // launcher thread rather than a unique pid per thread.
1560 // Use gettid() if you want the old pre NPTL behaviour.
1562 // if you are looking for the result of a call to getpid() that
1563 // returns a unique pid for the calling thread, then look at the
1564 // OSThread::thread_id() method in osThread_linux.hpp file
1566 return (int)(_initial_pid ? _initial_pid : getpid());
1567 }
1569 // DLL functions
1571 const char* os::dll_file_extension() { return ".so"; }
1573 // This must be hard coded because it's the system's temporary
1574 // directory not the java application's temp directory, ala java.io.tmpdir.
1575 const char* os::get_temp_directory() { return "/tmp"; }
1577 static bool file_exists(const char* filename) {
1578 struct stat statbuf;
1579 if (filename == NULL || strlen(filename) == 0) {
1580 return false;
1581 }
1582 return os::stat(filename, &statbuf) == 0;
1583 }
1585 bool os::dll_build_name(char* buffer, size_t buflen,
1586 const char* pname, const char* fname) {
1587 bool retval = false;
1588 // Copied from libhpi
1589 const size_t pnamelen = pname ? strlen(pname) : 0;
1591 // Return error on buffer overflow.
1592 if (pnamelen + strlen(fname) + 10 > (size_t) buflen) {
1593 return retval;
1594 }
1596 if (pnamelen == 0) {
1597 snprintf(buffer, buflen, "lib%s.so", fname);
1598 retval = true;
1599 } else if (strchr(pname, *os::path_separator()) != NULL) {
1600 int n;
1601 char** pelements = split_path(pname, &n);
1602 if (pelements == NULL) {
1603 return false;
1604 }
1605 for (int i = 0 ; i < n ; i++) {
1606 // Really shouldn't be NULL, but check can't hurt
1607 if (pelements[i] == NULL || strlen(pelements[i]) == 0) {
1608 continue; // skip the empty path values
1609 }
1610 snprintf(buffer, buflen, "%s/lib%s.so", pelements[i], fname);
1611 if (file_exists(buffer)) {
1612 retval = true;
1613 break;
1614 }
1615 }
1616 // release the storage
1617 for (int i = 0 ; i < n ; i++) {
1618 if (pelements[i] != NULL) {
1619 FREE_C_HEAP_ARRAY(char, pelements[i], mtInternal);
1620 }
1621 }
1622 if (pelements != NULL) {
1623 FREE_C_HEAP_ARRAY(char*, pelements, mtInternal);
1624 }
1625 } else {
1626 snprintf(buffer, buflen, "%s/lib%s.so", pname, fname);
1627 retval = true;
1628 }
1629 return retval;
1630 }
1632 // check if addr is inside libjvm.so
1633 bool os::address_is_in_vm(address addr) {
1634 static address libjvm_base_addr;
1635 Dl_info dlinfo;
1637 if (libjvm_base_addr == NULL) {
1638 if (dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo) != 0) {
1639 libjvm_base_addr = (address)dlinfo.dli_fbase;
1640 }
1641 assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm");
1642 }
1644 if (dladdr((void *)addr, &dlinfo) != 0) {
1645 if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true;
1646 }
1648 return false;
1649 }
1651 bool os::dll_address_to_function_name(address addr, char *buf,
1652 int buflen, int *offset) {
1653 // buf is not optional, but offset is optional
1654 assert(buf != NULL, "sanity check");
1656 Dl_info dlinfo;
1658 if (dladdr((void*)addr, &dlinfo) != 0) {
1659 // see if we have a matching symbol
1660 if (dlinfo.dli_saddr != NULL && dlinfo.dli_sname != NULL) {
1661 if (!Decoder::demangle(dlinfo.dli_sname, buf, buflen)) {
1662 jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname);
1663 }
1664 if (offset != NULL) *offset = addr - (address)dlinfo.dli_saddr;
1665 return true;
1666 }
1667 // no matching symbol so try for just file info
1668 if (dlinfo.dli_fname != NULL && dlinfo.dli_fbase != NULL) {
1669 if (Decoder::decode((address)(addr - (address)dlinfo.dli_fbase),
1670 buf, buflen, offset, dlinfo.dli_fname)) {
1671 return true;
1672 }
1673 }
1674 }
1676 buf[0] = '\0';
1677 if (offset != NULL) *offset = -1;
1678 return false;
1679 }
1681 struct _address_to_library_name {
1682 address addr; // input : memory address
1683 size_t buflen; // size of fname
1684 char* fname; // output: library name
1685 address base; // library base addr
1686 };
1688 static int address_to_library_name_callback(struct dl_phdr_info *info,
1689 size_t size, void *data) {
1690 int i;
1691 bool found = false;
1692 address libbase = NULL;
1693 struct _address_to_library_name * d = (struct _address_to_library_name *)data;
1695 // iterate through all loadable segments
1696 for (i = 0; i < info->dlpi_phnum; i++) {
1697 address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr);
1698 if (info->dlpi_phdr[i].p_type == PT_LOAD) {
1699 // base address of a library is the lowest address of its loaded
1700 // segments.
1701 if (libbase == NULL || libbase > segbase) {
1702 libbase = segbase;
1703 }
1704 // see if 'addr' is within current segment
1705 if (segbase <= d->addr &&
1706 d->addr < segbase + info->dlpi_phdr[i].p_memsz) {
1707 found = true;
1708 }
1709 }
1710 }
1712 // dlpi_name is NULL or empty if the ELF file is executable, return 0
1713 // so dll_address_to_library_name() can fall through to use dladdr() which
1714 // can figure out executable name from argv[0].
1715 if (found && info->dlpi_name && info->dlpi_name[0]) {
1716 d->base = libbase;
1717 if (d->fname) {
1718 jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name);
1719 }
1720 return 1;
1721 }
1722 return 0;
1723 }
1725 bool os::dll_address_to_library_name(address addr, char* buf,
1726 int buflen, int* offset) {
1727 // buf is not optional, but offset is optional
1728 assert(buf != NULL, "sanity check");
1730 Dl_info dlinfo;
1731 struct _address_to_library_name data;
1733 // There is a bug in old glibc dladdr() implementation that it could resolve
1734 // to wrong library name if the .so file has a base address != NULL. Here
1735 // we iterate through the program headers of all loaded libraries to find
1736 // out which library 'addr' really belongs to. This workaround can be
1737 // removed once the minimum requirement for glibc is moved to 2.3.x.
1738 data.addr = addr;
1739 data.fname = buf;
1740 data.buflen = buflen;
1741 data.base = NULL;
1742 int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data);
1744 if (rslt) {
1745 // buf already contains library name
1746 if (offset) *offset = addr - data.base;
1747 return true;
1748 }
1749 if (dladdr((void*)addr, &dlinfo) != 0) {
1750 if (dlinfo.dli_fname != NULL) {
1751 jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname);
1752 }
1753 if (dlinfo.dli_fbase != NULL && offset != NULL) {
1754 *offset = addr - (address)dlinfo.dli_fbase;
1755 }
1756 return true;
1757 }
1759 buf[0] = '\0';
1760 if (offset) *offset = -1;
1761 return false;
1762 }
1764 // Loads .dll/.so and
1765 // in case of error it checks if .dll/.so was built for the
1766 // same architecture as Hotspot is running on
1769 // Remember the stack's state. The Linux dynamic linker will change
1770 // the stack to 'executable' at most once, so we must safepoint only once.
1771 bool os::Linux::_stack_is_executable = false;
1773 // VM operation that loads a library. This is necessary if stack protection
1774 // of the Java stacks can be lost during loading the library. If we
1775 // do not stop the Java threads, they can stack overflow before the stacks
1776 // are protected again.
1777 class VM_LinuxDllLoad: public VM_Operation {
1778 private:
1779 const char *_filename;
1780 char *_ebuf;
1781 int _ebuflen;
1782 void *_lib;
1783 public:
1784 VM_LinuxDllLoad(const char *fn, char *ebuf, int ebuflen) :
1785 _filename(fn), _ebuf(ebuf), _ebuflen(ebuflen), _lib(NULL) {}
1786 VMOp_Type type() const { return VMOp_LinuxDllLoad; }
1787 void doit() {
1788 _lib = os::Linux::dll_load_in_vmthread(_filename, _ebuf, _ebuflen);
1789 os::Linux::_stack_is_executable = true;
1790 }
1791 void* loaded_library() { return _lib; }
1792 };
1794 void * os::dll_load(const char *filename, char *ebuf, int ebuflen)
1795 {
1796 void * result = NULL;
1797 bool load_attempted = false;
1799 // Check whether the library to load might change execution rights
1800 // of the stack. If they are changed, the protection of the stack
1801 // guard pages will be lost. We need a safepoint to fix this.
1802 //
1803 // See Linux man page execstack(8) for more info.
1804 if (os::uses_stack_guard_pages() && !os::Linux::_stack_is_executable) {
1805 ElfFile ef(filename);
1806 if (!ef.specifies_noexecstack()) {
1807 if (!is_init_completed()) {
1808 os::Linux::_stack_is_executable = true;
1809 // This is OK - No Java threads have been created yet, and hence no
1810 // stack guard pages to fix.
1811 //
1812 // This should happen only when you are building JDK7 using a very
1813 // old version of JDK6 (e.g., with JPRT) and running test_gamma.
1814 //
1815 // Dynamic loader will make all stacks executable after
1816 // this function returns, and will not do that again.
1817 assert(Threads::first() == NULL, "no Java threads should exist yet.");
1818 } else {
1819 warning("You have loaded library %s which might have disabled stack guard. "
1820 "The VM will try to fix the stack guard now.\n"
1821 "It's highly recommended that you fix the library with "
1822 "'execstack -c <libfile>', or link it with '-z noexecstack'.",
1823 filename);
1825 assert(Thread::current()->is_Java_thread(), "must be Java thread");
1826 JavaThread *jt = JavaThread::current();
1827 if (jt->thread_state() != _thread_in_native) {
1828 // This happens when a compiler thread tries to load a hsdis-<arch>.so file
1829 // that requires ExecStack. Cannot enter safe point. Let's give up.
1830 warning("Unable to fix stack guard. Giving up.");
1831 } else {
1832 if (!LoadExecStackDllInVMThread) {
1833 // This is for the case where the DLL has an static
1834 // constructor function that executes JNI code. We cannot
1835 // load such DLLs in the VMThread.
1836 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen);
1837 }
1839 ThreadInVMfromNative tiv(jt);
1840 debug_only(VMNativeEntryWrapper vew;)
1842 VM_LinuxDllLoad op(filename, ebuf, ebuflen);
1843 VMThread::execute(&op);
1844 if (LoadExecStackDllInVMThread) {
1845 result = op.loaded_library();
1846 }
1847 load_attempted = true;
1848 }
1849 }
1850 }
1851 }
1853 if (!load_attempted) {
1854 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen);
1855 }
1857 if (result != NULL) {
1858 // Successful loading
1859 return result;
1860 }
1862 Elf32_Ehdr elf_head;
1863 int diag_msg_max_length=ebuflen-strlen(ebuf);
1864 char* diag_msg_buf=ebuf+strlen(ebuf);
1866 if (diag_msg_max_length==0) {
1867 // No more space in ebuf for additional diagnostics message
1868 return NULL;
1869 }
1872 int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK);
1874 if (file_descriptor < 0) {
1875 // Can't open library, report dlerror() message
1876 return NULL;
1877 }
1879 bool failed_to_read_elf_head=
1880 (sizeof(elf_head)!=
1881 (::read(file_descriptor, &elf_head,sizeof(elf_head)))) ;
1883 ::close(file_descriptor);
1884 if (failed_to_read_elf_head) {
1885 // file i/o error - report dlerror() msg
1886 return NULL;
1887 }
1889 typedef struct {
1890 Elf32_Half code; // Actual value as defined in elf.h
1891 Elf32_Half compat_class; // Compatibility of archs at VM's sense
1892 char elf_class; // 32 or 64 bit
1893 char endianess; // MSB or LSB
1894 char* name; // String representation
1895 } arch_t;
1897 #ifndef EM_486
1898 #define EM_486 6 /* Intel 80486 */
1899 #endif
1901 static const arch_t arch_array[]={
1902 {EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
1903 {EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
1904 {EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"},
1905 {EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"},
1906 {EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
1907 {EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
1908 {EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"},
1909 {EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"},
1910 #if defined(VM_LITTLE_ENDIAN)
1911 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2LSB, (char*)"Power PC 64"},
1912 #else
1913 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"},
1914 #endif
1915 {EM_ARM, EM_ARM, ELFCLASS32, ELFDATA2LSB, (char*)"ARM"},
1916 {EM_S390, EM_S390, ELFCLASSNONE, ELFDATA2MSB, (char*)"IBM System/390"},
1917 {EM_ALPHA, EM_ALPHA, ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"},
1918 {EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"},
1919 {EM_MIPS, EM_MIPS, ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"},
1920 {EM_MIPS, EM_MIPS, ELFCLASS64, ELFDATA2LSB, (char*)"MIPS64 LE"},
1921 {EM_PARISC, EM_PARISC, ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"},
1922 {EM_68K, EM_68K, ELFCLASS32, ELFDATA2MSB, (char*)"M68k"}
1923 };
1925 #if (defined IA32)
1926 static Elf32_Half running_arch_code=EM_386;
1927 #elif (defined AMD64)
1928 static Elf32_Half running_arch_code=EM_X86_64;
1929 #elif (defined IA64)
1930 static Elf32_Half running_arch_code=EM_IA_64;
1931 #elif (defined __sparc) && (defined _LP64)
1932 static Elf32_Half running_arch_code=EM_SPARCV9;
1933 #elif (defined __sparc) && (!defined _LP64)
1934 static Elf32_Half running_arch_code=EM_SPARC;
1935 #elif (defined MIPS64)
1936 static Elf32_Half running_arch_code=EM_MIPS;
1937 #elif (defined __powerpc64__)
1938 static Elf32_Half running_arch_code=EM_PPC64;
1939 #elif (defined __powerpc__)
1940 static Elf32_Half running_arch_code=EM_PPC;
1941 #elif (defined ARM)
1942 static Elf32_Half running_arch_code=EM_ARM;
1943 #elif (defined S390)
1944 static Elf32_Half running_arch_code=EM_S390;
1945 #elif (defined ALPHA)
1946 static Elf32_Half running_arch_code=EM_ALPHA;
1947 #elif (defined MIPSEL)
1948 static Elf32_Half running_arch_code=EM_MIPS_RS3_LE;
1949 #elif (defined PARISC)
1950 static Elf32_Half running_arch_code=EM_PARISC;
1951 #elif (defined MIPS)
1952 static Elf32_Half running_arch_code=EM_MIPS;
1953 #elif (defined M68K)
1954 static Elf32_Half running_arch_code=EM_68K;
1955 #else
1956 #error Method os::dll_load requires that one of following is defined:\
1957 IA32, AMD64, IA64, __sparc, __powerpc__, ARM, S390, ALPHA, MIPS, MIPSEL, __mips64, PARISC, M68K
1958 #endif
1960 // Identify compatability class for VM's architecture and library's architecture
1961 // Obtain string descriptions for architectures
1963 arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL};
1964 int running_arch_index=-1;
1966 for (unsigned int i=0 ; i < ARRAY_SIZE(arch_array) ; i++ ) {
1967 if (running_arch_code == arch_array[i].code) {
1968 running_arch_index = i;
1969 }
1970 if (lib_arch.code == arch_array[i].code) {
1971 lib_arch.compat_class = arch_array[i].compat_class;
1972 lib_arch.name = arch_array[i].name;
1973 }
1974 }
1976 assert(running_arch_index != -1,
1977 "Didn't find running architecture code (running_arch_code) in arch_array");
1978 if (running_arch_index == -1) {
1979 // Even though running architecture detection failed
1980 // we may still continue with reporting dlerror() message
1981 return NULL;
1982 }
1984 if (lib_arch.endianess != arch_array[running_arch_index].endianess) {
1985 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)");
1986 return NULL;
1987 }
1989 #ifndef S390
1990 if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) {
1991 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)");
1992 return NULL;
1993 }
1994 #endif // !S390
1996 if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) {
1997 if ( lib_arch.name!=NULL ) {
1998 ::snprintf(diag_msg_buf, diag_msg_max_length-1,
1999 " (Possible cause: can't load %s-bit .so on a %s-bit platform)",
2000 lib_arch.name, arch_array[running_arch_index].name);
2001 } else {
2002 ::snprintf(diag_msg_buf, diag_msg_max_length-1,
2003 " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)",
2004 lib_arch.code,
2005 arch_array[running_arch_index].name);
2006 }
2007 }
2009 return NULL;
2010 }
2012 void * os::Linux::dlopen_helper(const char *filename, char *ebuf, int ebuflen) {
2013 void * result = ::dlopen(filename, RTLD_LAZY);
2014 if (result == NULL) {
2015 ::strncpy(ebuf, ::dlerror(), ebuflen - 1);
2016 ebuf[ebuflen-1] = '\0';
2017 }
2018 return result;
2019 }
2021 void * os::Linux::dll_load_in_vmthread(const char *filename, char *ebuf, int ebuflen) {
2022 void * result = NULL;
2023 if (LoadExecStackDllInVMThread) {
2024 result = dlopen_helper(filename, ebuf, ebuflen);
2025 }
2027 // Since 7019808, libjvm.so is linked with -noexecstack. If the VM loads a
2028 // library that requires an executable stack, or which does not have this
2029 // stack attribute set, dlopen changes the stack attribute to executable. The
2030 // read protection of the guard pages gets lost.
2031 //
2032 // Need to check _stack_is_executable again as multiple VM_LinuxDllLoad
2033 // may have been queued at the same time.
2035 if (!_stack_is_executable) {
2036 JavaThread *jt = Threads::first();
2038 while (jt) {
2039 if (!jt->stack_guard_zone_unused() && // Stack not yet fully initialized
2040 jt->stack_yellow_zone_enabled()) { // No pending stack overflow exceptions
2041 if (!os::guard_memory((char *) jt->stack_red_zone_base() - jt->stack_red_zone_size(),
2042 jt->stack_yellow_zone_size() + jt->stack_red_zone_size())) {
2043 warning("Attempt to reguard stack yellow zone failed.");
2044 }
2045 }
2046 jt = jt->next();
2047 }
2048 }
2050 return result;
2051 }
2053 /*
2054 * glibc-2.0 libdl is not MT safe. If you are building with any glibc,
2055 * chances are you might want to run the generated bits against glibc-2.0
2056 * libdl.so, so always use locking for any version of glibc.
2057 */
2058 void* os::dll_lookup(void* handle, const char* name) {
2059 pthread_mutex_lock(&dl_mutex);
2060 void* res = dlsym(handle, name);
2061 pthread_mutex_unlock(&dl_mutex);
2062 return res;
2063 }
2065 void* os::get_default_process_handle() {
2066 return (void*)::dlopen(NULL, RTLD_LAZY);
2067 }
2069 static bool _print_ascii_file(const char* filename, outputStream* st) {
2070 int fd = ::open(filename, O_RDONLY);
2071 if (fd == -1) {
2072 return false;
2073 }
2075 char buf[32];
2076 int bytes;
2077 while ((bytes = ::read(fd, buf, sizeof(buf))) > 0) {
2078 st->print_raw(buf, bytes);
2079 }
2081 ::close(fd);
2083 return true;
2084 }
2086 void os::print_dll_info(outputStream *st) {
2087 st->print_cr("Dynamic libraries:");
2089 char fname[32];
2090 pid_t pid = os::Linux::gettid();
2092 jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid);
2094 if (!_print_ascii_file(fname, st)) {
2095 st->print("Can not get library information for pid = %d\n", pid);
2096 }
2097 }
2099 void os::print_os_info_brief(outputStream* st) {
2100 os::Linux::print_distro_info(st);
2102 os::Posix::print_uname_info(st);
2104 os::Linux::print_libversion_info(st);
2106 }
2108 void os::print_os_info(outputStream* st) {
2109 st->print("OS:");
2111 os::Linux::print_distro_info(st);
2113 os::Posix::print_uname_info(st);
2115 // Print warning if unsafe chroot environment detected
2116 if (unsafe_chroot_detected) {
2117 st->print("WARNING!! ");
2118 st->print_cr("%s", unstable_chroot_error);
2119 }
2121 os::Linux::print_libversion_info(st);
2123 os::Posix::print_rlimit_info(st);
2125 os::Posix::print_load_average(st);
2127 os::Linux::print_full_memory_info(st);
2128 }
2130 // Try to identify popular distros.
2131 // Most Linux distributions have a /etc/XXX-release file, which contains
2132 // the OS version string. Newer Linux distributions have a /etc/lsb-release
2133 // file that also contains the OS version string. Some have more than one
2134 // /etc/XXX-release file (e.g. Mandrake has both /etc/mandrake-release and
2135 // /etc/redhat-release.), so the order is important.
2136 // Any Linux that is based on Redhat (i.e. Oracle, Mandrake, Sun JDS...) have
2137 // their own specific XXX-release file as well as a redhat-release file.
2138 // Because of this the XXX-release file needs to be searched for before the
2139 // redhat-release file.
2140 // Since Red Hat has a lsb-release file that is not very descriptive the
2141 // search for redhat-release needs to be before lsb-release.
2142 // Since the lsb-release file is the new standard it needs to be searched
2143 // before the older style release files.
2144 // Searching system-release (Red Hat) and os-release (other Linuxes) are a
2145 // next to last resort. The os-release file is a new standard that contains
2146 // distribution information and the system-release file seems to be an old
2147 // standard that has been replaced by the lsb-release and os-release files.
2148 // Searching for the debian_version file is the last resort. It contains
2149 // an informative string like "6.0.6" or "wheezy/sid". Because of this
2150 // "Debian " is printed before the contents of the debian_version file.
2151 void os::Linux::print_distro_info(outputStream* st) {
2152 if (!_print_ascii_file("/etc/oracle-release", st) &&
2153 !_print_ascii_file("/etc/mandriva-release", st) &&
2154 !_print_ascii_file("/etc/mandrake-release", st) &&
2155 !_print_ascii_file("/etc/sun-release", st) &&
2156 !_print_ascii_file("/etc/redhat-release", st) &&
2157 !_print_ascii_file("/etc/lsb-release", st) &&
2158 !_print_ascii_file("/etc/SuSE-release", st) &&
2159 !_print_ascii_file("/etc/turbolinux-release", st) &&
2160 !_print_ascii_file("/etc/gentoo-release", st) &&
2161 !_print_ascii_file("/etc/ltib-release", st) &&
2162 !_print_ascii_file("/etc/angstrom-version", st) &&
2163 !_print_ascii_file("/etc/system-release", st) &&
2164 !_print_ascii_file("/etc/os-release", st)) {
2166 if (file_exists("/etc/debian_version")) {
2167 st->print("Debian ");
2168 _print_ascii_file("/etc/debian_version", st);
2169 } else {
2170 st->print("Linux");
2171 }
2172 }
2173 st->cr();
2174 }
2176 void os::Linux::print_libversion_info(outputStream* st) {
2177 // libc, pthread
2178 st->print("libc:");
2179 st->print("%s ", os::Linux::glibc_version());
2180 st->print("%s ", os::Linux::libpthread_version());
2181 if (os::Linux::is_LinuxThreads()) {
2182 st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed");
2183 }
2184 st->cr();
2185 }
2187 void os::Linux::print_full_memory_info(outputStream* st) {
2188 st->print("\n/proc/meminfo:\n");
2189 _print_ascii_file("/proc/meminfo", st);
2190 st->cr();
2191 }
2193 void os::print_memory_info(outputStream* st) {
2195 st->print("Memory:");
2196 st->print(" %dk page", os::vm_page_size()>>10);
2198 // values in struct sysinfo are "unsigned long"
2199 struct sysinfo si;
2200 sysinfo(&si);
2202 st->print(", physical " UINT64_FORMAT "k",
2203 os::physical_memory() >> 10);
2204 st->print("(" UINT64_FORMAT "k free)",
2205 os::available_memory() >> 10);
2206 st->print(", swap " UINT64_FORMAT "k",
2207 ((jlong)si.totalswap * si.mem_unit) >> 10);
2208 st->print("(" UINT64_FORMAT "k free)",
2209 ((jlong)si.freeswap * si.mem_unit) >> 10);
2210 st->cr();
2211 }
2213 void os::pd_print_cpu_info(outputStream* st) {
2214 st->print("\n/proc/cpuinfo:\n");
2215 if (!_print_ascii_file("/proc/cpuinfo", st)) {
2216 st->print(" <Not Available>");
2217 }
2218 st->cr();
2219 }
2221 void os::print_siginfo(outputStream* st, void* siginfo) {
2222 const siginfo_t* si = (const siginfo_t*)siginfo;
2224 os::Posix::print_siginfo_brief(st, si);
2225 #if INCLUDE_CDS
2226 if (si && (si->si_signo == SIGBUS || si->si_signo == SIGSEGV) &&
2227 UseSharedSpaces) {
2228 FileMapInfo* mapinfo = FileMapInfo::current_info();
2229 if (mapinfo->is_in_shared_space(si->si_addr)) {
2230 st->print("\n\nError accessing class data sharing archive." \
2231 " Mapped file inaccessible during execution, " \
2232 " possible disk/network problem.");
2233 }
2234 }
2235 #endif
2236 st->cr();
2237 }
2240 static void print_signal_handler(outputStream* st, int sig,
2241 char* buf, size_t buflen);
2243 void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) {
2244 st->print_cr("Signal Handlers:");
2245 print_signal_handler(st, SIGSEGV, buf, buflen);
2246 print_signal_handler(st, SIGBUS , buf, buflen);
2247 print_signal_handler(st, SIGFPE , buf, buflen);
2248 print_signal_handler(st, SIGPIPE, buf, buflen);
2249 print_signal_handler(st, SIGXFSZ, buf, buflen);
2250 print_signal_handler(st, SIGILL , buf, buflen);
2251 print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen);
2252 print_signal_handler(st, SR_signum, buf, buflen);
2253 print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen);
2254 print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen);
2255 print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen);
2256 print_signal_handler(st, BREAK_SIGNAL, buf, buflen);
2257 #if defined(PPC64)
2258 print_signal_handler(st, SIGTRAP, buf, buflen);
2259 #endif
2260 }
2262 static char saved_jvm_path[MAXPATHLEN] = {0};
2264 // Find the full path to the current module, libjvm.so
2265 void os::jvm_path(char *buf, jint buflen) {
2266 // Error checking.
2267 if (buflen < MAXPATHLEN) {
2268 assert(false, "must use a large-enough buffer");
2269 buf[0] = '\0';
2270 return;
2271 }
2272 // Lazy resolve the path to current module.
2273 if (saved_jvm_path[0] != 0) {
2274 strcpy(buf, saved_jvm_path);
2275 return;
2276 }
2278 char dli_fname[MAXPATHLEN];
2279 bool ret = dll_address_to_library_name(
2280 CAST_FROM_FN_PTR(address, os::jvm_path),
2281 dli_fname, sizeof(dli_fname), NULL);
2282 assert(ret, "cannot locate libjvm");
2283 char *rp = NULL;
2284 if (ret && dli_fname[0] != '\0') {
2285 rp = realpath(dli_fname, buf);
2286 }
2287 if (rp == NULL)
2288 return;
2290 if (Arguments::created_by_gamma_launcher()) {
2291 // Support for the gamma launcher. Typical value for buf is
2292 // "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so". If "/jre/lib/" appears at
2293 // the right place in the string, then assume we are installed in a JDK and
2294 // we're done. Otherwise, check for a JAVA_HOME environment variable and fix
2295 // up the path so it looks like libjvm.so is installed there (append a
2296 // fake suffix hotspot/libjvm.so).
2297 const char *p = buf + strlen(buf) - 1;
2298 for (int count = 0; p > buf && count < 5; ++count) {
2299 for (--p; p > buf && *p != '/'; --p)
2300 /* empty */ ;
2301 }
2303 if (strncmp(p, "/jre/lib/", 9) != 0) {
2304 // Look for JAVA_HOME in the environment.
2305 char* java_home_var = ::getenv("JAVA_HOME");
2306 if (java_home_var != NULL && java_home_var[0] != 0) {
2307 char* jrelib_p;
2308 int len;
2310 // Check the current module name "libjvm.so".
2311 p = strrchr(buf, '/');
2312 assert(strstr(p, "/libjvm") == p, "invalid library name");
2314 rp = realpath(java_home_var, buf);
2315 if (rp == NULL)
2316 return;
2318 // determine if this is a legacy image or modules image
2319 // modules image doesn't have "jre" subdirectory
2320 len = strlen(buf);
2321 assert(len < buflen, "Ran out of buffer room");
2322 jrelib_p = buf + len;
2323 snprintf(jrelib_p, buflen-len, "/jre/lib/%s", cpu_arch);
2324 if (0 != access(buf, F_OK)) {
2325 snprintf(jrelib_p, buflen-len, "/lib/%s", cpu_arch);
2326 }
2328 if (0 == access(buf, F_OK)) {
2329 // Use current module name "libjvm.so"
2330 len = strlen(buf);
2331 snprintf(buf + len, buflen-len, "/hotspot/libjvm.so");
2332 } else {
2333 // Go back to path of .so
2334 rp = realpath(dli_fname, buf);
2335 if (rp == NULL)
2336 return;
2337 }
2338 }
2339 }
2340 }
2342 strncpy(saved_jvm_path, buf, MAXPATHLEN);
2343 }
2345 void os::print_jni_name_prefix_on(outputStream* st, int args_size) {
2346 // no prefix required, not even "_"
2347 }
2349 void os::print_jni_name_suffix_on(outputStream* st, int args_size) {
2350 // no suffix required
2351 }
2353 ////////////////////////////////////////////////////////////////////////////////
2354 // sun.misc.Signal support
2356 static volatile jint sigint_count = 0;
2358 static void
2359 UserHandler(int sig, void *siginfo, void *context) {
2360 // 4511530 - sem_post is serialized and handled by the manager thread. When
2361 // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We
2362 // don't want to flood the manager thread with sem_post requests.
2363 if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1)
2364 return;
2366 // Ctrl-C is pressed during error reporting, likely because the error
2367 // handler fails to abort. Let VM die immediately.
2368 if (sig == SIGINT && is_error_reported()) {
2369 os::die();
2370 }
2372 os::signal_notify(sig);
2373 }
2375 void* os::user_handler() {
2376 return CAST_FROM_FN_PTR(void*, UserHandler);
2377 }
2379 class Semaphore : public StackObj {
2380 public:
2381 Semaphore();
2382 ~Semaphore();
2383 void signal();
2384 void wait();
2385 bool trywait();
2386 bool timedwait(unsigned int sec, int nsec);
2387 private:
2388 sem_t _semaphore;
2389 };
2391 Semaphore::Semaphore() {
2392 sem_init(&_semaphore, 0, 0);
2393 }
2395 Semaphore::~Semaphore() {
2396 sem_destroy(&_semaphore);
2397 }
2399 void Semaphore::signal() {
2400 sem_post(&_semaphore);
2401 }
2403 void Semaphore::wait() {
2404 sem_wait(&_semaphore);
2405 }
2407 bool Semaphore::trywait() {
2408 return sem_trywait(&_semaphore) == 0;
2409 }
2411 bool Semaphore::timedwait(unsigned int sec, int nsec) {
2413 struct timespec ts;
2414 // Semaphore's are always associated with CLOCK_REALTIME
2415 os::Linux::clock_gettime(CLOCK_REALTIME, &ts);
2416 // see unpackTime for discussion on overflow checking
2417 if (sec >= MAX_SECS) {
2418 ts.tv_sec += MAX_SECS;
2419 ts.tv_nsec = 0;
2420 } else {
2421 ts.tv_sec += sec;
2422 ts.tv_nsec += nsec;
2423 if (ts.tv_nsec >= NANOSECS_PER_SEC) {
2424 ts.tv_nsec -= NANOSECS_PER_SEC;
2425 ++ts.tv_sec; // note: this must be <= max_secs
2426 }
2427 }
2429 while (1) {
2430 int result = sem_timedwait(&_semaphore, &ts);
2431 if (result == 0) {
2432 return true;
2433 } else if (errno == EINTR) {
2434 continue;
2435 } else if (errno == ETIMEDOUT) {
2436 return false;
2437 } else {
2438 return false;
2439 }
2440 }
2441 }
2443 extern "C" {
2444 typedef void (*sa_handler_t)(int);
2445 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *);
2446 }
2448 void* os::signal(int signal_number, void* handler) {
2449 struct sigaction sigAct, oldSigAct;
2451 sigfillset(&(sigAct.sa_mask));
2452 sigAct.sa_flags = SA_RESTART|SA_SIGINFO;
2453 sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler);
2455 if (sigaction(signal_number, &sigAct, &oldSigAct)) {
2456 // -1 means registration failed
2457 return (void *)-1;
2458 }
2460 return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler);
2461 }
2463 void os::signal_raise(int signal_number) {
2464 ::raise(signal_number);
2465 }
2467 /*
2468 * The following code is moved from os.cpp for making this
2469 * code platform specific, which it is by its very nature.
2470 */
2472 // Will be modified when max signal is changed to be dynamic
2473 int os::sigexitnum_pd() {
2474 return NSIG;
2475 }
2477 // a counter for each possible signal value
2478 static volatile jint pending_signals[NSIG+1] = { 0 };
2480 // Linux(POSIX) specific hand shaking semaphore.
2481 static sem_t sig_sem;
2482 static Semaphore sr_semaphore;
2484 void os::signal_init_pd() {
2485 // Initialize signal structures
2486 ::memset((void*)pending_signals, 0, sizeof(pending_signals));
2488 // Initialize signal semaphore
2489 ::sem_init(&sig_sem, 0, 0);
2490 }
2492 void os::signal_notify(int sig) {
2493 Atomic::inc(&pending_signals[sig]);
2494 ::sem_post(&sig_sem);
2495 }
2497 static int check_pending_signals(bool wait) {
2498 Atomic::store(0, &sigint_count);
2499 for (;;) {
2500 for (int i = 0; i < NSIG + 1; i++) {
2501 jint n = pending_signals[i];
2502 if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) {
2503 return i;
2504 }
2505 }
2506 if (!wait) {
2507 return -1;
2508 }
2509 JavaThread *thread = JavaThread::current();
2510 ThreadBlockInVM tbivm(thread);
2512 bool threadIsSuspended;
2513 do {
2514 thread->set_suspend_equivalent();
2515 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
2516 ::sem_wait(&sig_sem);
2518 // were we externally suspended while we were waiting?
2519 threadIsSuspended = thread->handle_special_suspend_equivalent_condition();
2520 if (threadIsSuspended) {
2521 //
2522 // The semaphore has been incremented, but while we were waiting
2523 // another thread suspended us. We don't want to continue running
2524 // while suspended because that would surprise the thread that
2525 // suspended us.
2526 //
2527 ::sem_post(&sig_sem);
2529 thread->java_suspend_self();
2530 }
2531 } while (threadIsSuspended);
2532 }
2533 }
2535 int os::signal_lookup() {
2536 return check_pending_signals(false);
2537 }
2539 int os::signal_wait() {
2540 return check_pending_signals(true);
2541 }
2543 ////////////////////////////////////////////////////////////////////////////////
2544 // Virtual Memory
2546 int os::vm_page_size() {
2547 // Seems redundant as all get out
2548 assert(os::Linux::page_size() != -1, "must call os::init");
2549 return os::Linux::page_size();
2550 }
2552 // Solaris allocates memory by pages.
2553 int os::vm_allocation_granularity() {
2554 assert(os::Linux::page_size() != -1, "must call os::init");
2555 return os::Linux::page_size();
2556 }
2558 // Rationale behind this function:
2559 // current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable
2560 // mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get
2561 // samples for JITted code. Here we create private executable mapping over the code cache
2562 // and then we can use standard (well, almost, as mapping can change) way to provide
2563 // info for the reporting script by storing timestamp and location of symbol
2564 void linux_wrap_code(char* base, size_t size) {
2565 static volatile jint cnt = 0;
2567 if (!UseOprofile) {
2568 return;
2569 }
2571 char buf[PATH_MAX+1];
2572 int num = Atomic::add(1, &cnt);
2574 snprintf(buf, sizeof(buf), "%s/hs-vm-%d-%d",
2575 os::get_temp_directory(), os::current_process_id(), num);
2576 unlink(buf);
2578 int fd = ::open(buf, O_CREAT | O_RDWR, S_IRWXU);
2580 if (fd != -1) {
2581 off_t rv = ::lseek(fd, size-2, SEEK_SET);
2582 if (rv != (off_t)-1) {
2583 if (::write(fd, "", 1) == 1) {
2584 mmap(base, size,
2585 PROT_READ|PROT_WRITE|PROT_EXEC,
2586 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0);
2587 }
2588 }
2589 ::close(fd);
2590 unlink(buf);
2591 }
2592 }
2594 static bool recoverable_mmap_error(int err) {
2595 // See if the error is one we can let the caller handle. This
2596 // list of errno values comes from JBS-6843484. I can't find a
2597 // Linux man page that documents this specific set of errno
2598 // values so while this list currently matches Solaris, it may
2599 // change as we gain experience with this failure mode.
2600 switch (err) {
2601 case EBADF:
2602 case EINVAL:
2603 case ENOTSUP:
2604 // let the caller deal with these errors
2605 return true;
2607 default:
2608 // Any remaining errors on this OS can cause our reserved mapping
2609 // to be lost. That can cause confusion where different data
2610 // structures think they have the same memory mapped. The worst
2611 // scenario is if both the VM and a library think they have the
2612 // same memory mapped.
2613 return false;
2614 }
2615 }
2617 static void warn_fail_commit_memory(char* addr, size_t size, bool exec,
2618 int err) {
2619 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT
2620 ", %d) failed; error='%s' (errno=%d)", addr, size, exec,
2621 strerror(err), err);
2622 }
2624 static void warn_fail_commit_memory(char* addr, size_t size,
2625 size_t alignment_hint, bool exec,
2626 int err) {
2627 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT
2628 ", " SIZE_FORMAT ", %d) failed; error='%s' (errno=%d)", addr, size,
2629 alignment_hint, exec, strerror(err), err);
2630 }
2632 // NOTE: Linux kernel does not really reserve the pages for us.
2633 // All it does is to check if there are enough free pages
2634 // left at the time of mmap(). This could be a potential
2635 // problem.
2636 int os::Linux::commit_memory_impl(char* addr, size_t size, bool exec) {
2637 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
2638 uintptr_t res = (uintptr_t) ::mmap(addr, size, prot,
2639 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0);
2640 if (res != (uintptr_t) MAP_FAILED) {
2641 if (UseNUMAInterleaving) {
2642 numa_make_global(addr, size);
2643 }
2644 return 0;
2645 }
2647 int err = errno; // save errno from mmap() call above
2649 if (!recoverable_mmap_error(err)) {
2650 warn_fail_commit_memory(addr, size, exec, err);
2651 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, "committing reserved memory.");
2652 }
2654 return err;
2655 }
2657 bool os::pd_commit_memory(char* addr, size_t size, bool exec) {
2658 return os::Linux::commit_memory_impl(addr, size, exec) == 0;
2659 }
2661 void os::pd_commit_memory_or_exit(char* addr, size_t size, bool exec,
2662 const char* mesg) {
2663 assert(mesg != NULL, "mesg must be specified");
2664 int err = os::Linux::commit_memory_impl(addr, size, exec);
2665 if (err != 0) {
2666 // the caller wants all commit errors to exit with the specified mesg:
2667 warn_fail_commit_memory(addr, size, exec, err);
2668 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg);
2669 }
2670 }
2672 // Define MAP_HUGETLB here so we can build HotSpot on old systems.
2673 #ifndef MAP_HUGETLB
2674 #define MAP_HUGETLB 0x40000
2675 #endif
2677 // Define MADV_HUGEPAGE here so we can build HotSpot on old systems.
2678 #ifndef MADV_HUGEPAGE
2679 #define MADV_HUGEPAGE 14
2680 #endif
2682 int os::Linux::commit_memory_impl(char* addr, size_t size,
2683 size_t alignment_hint, bool exec) {
2684 int err = os::Linux::commit_memory_impl(addr, size, exec);
2685 if (err == 0) {
2686 realign_memory(addr, size, alignment_hint);
2687 }
2688 return err;
2689 }
2691 bool os::pd_commit_memory(char* addr, size_t size, size_t alignment_hint,
2692 bool exec) {
2693 return os::Linux::commit_memory_impl(addr, size, alignment_hint, exec) == 0;
2694 }
2696 void os::pd_commit_memory_or_exit(char* addr, size_t size,
2697 size_t alignment_hint, bool exec,
2698 const char* mesg) {
2699 assert(mesg != NULL, "mesg must be specified");
2700 int err = os::Linux::commit_memory_impl(addr, size, alignment_hint, exec);
2701 if (err != 0) {
2702 // the caller wants all commit errors to exit with the specified mesg:
2703 warn_fail_commit_memory(addr, size, alignment_hint, exec, err);
2704 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg);
2705 }
2706 }
2708 void os::pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint) {
2709 if (UseTransparentHugePages && alignment_hint > (size_t)vm_page_size()) {
2710 // We don't check the return value: madvise(MADV_HUGEPAGE) may not
2711 // be supported or the memory may already be backed by huge pages.
2712 ::madvise(addr, bytes, MADV_HUGEPAGE);
2713 }
2714 }
2716 void os::pd_free_memory(char *addr, size_t bytes, size_t alignment_hint) {
2717 // This method works by doing an mmap over an existing mmaping and effectively discarding
2718 // the existing pages. However it won't work for SHM-based large pages that cannot be
2719 // uncommitted at all. We don't do anything in this case to avoid creating a segment with
2720 // small pages on top of the SHM segment. This method always works for small pages, so we
2721 // allow that in any case.
2722 if (alignment_hint <= (size_t)os::vm_page_size() || can_commit_large_page_memory()) {
2723 commit_memory(addr, bytes, alignment_hint, !ExecMem);
2724 }
2725 }
2727 void os::numa_make_global(char *addr, size_t bytes) {
2728 Linux::numa_interleave_memory(addr, bytes);
2729 }
2731 // Define for numa_set_bind_policy(int). Setting the argument to 0 will set the
2732 // bind policy to MPOL_PREFERRED for the current thread.
2733 #define USE_MPOL_PREFERRED 0
2735 void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) {
2736 // To make NUMA and large pages more robust when both enabled, we need to ease
2737 // the requirements on where the memory should be allocated. MPOL_BIND is the
2738 // default policy and it will force memory to be allocated on the specified
2739 // node. Changing this to MPOL_PREFERRED will prefer to allocate the memory on
2740 // the specified node, but will not force it. Using this policy will prevent
2741 // getting SIGBUS when trying to allocate large pages on NUMA nodes with no
2742 // free large pages.
2743 Linux::numa_set_bind_policy(USE_MPOL_PREFERRED);
2744 Linux::numa_tonode_memory(addr, bytes, lgrp_hint);
2745 }
2747 bool os::numa_topology_changed() { return false; }
2749 size_t os::numa_get_groups_num() {
2750 // Return just the number of nodes in which it's possible to allocate memory
2751 // (in numa terminology, configured nodes).
2752 return Linux::numa_num_configured_nodes();
2753 }
2755 int os::numa_get_group_id() {
2756 int cpu_id = Linux::sched_getcpu();
2757 if (cpu_id != -1) {
2758 int lgrp_id = Linux::get_node_by_cpu(cpu_id);
2759 if (lgrp_id != -1) {
2760 return lgrp_id;
2761 }
2762 }
2763 return 0;
2764 }
2766 int os::Linux::get_existing_num_nodes() {
2767 size_t node;
2768 size_t highest_node_number = Linux::numa_max_node();
2769 int num_nodes = 0;
2771 // Get the total number of nodes in the system including nodes without memory.
2772 for (node = 0; node <= highest_node_number; node++) {
2773 if (isnode_in_existing_nodes(node)) {
2774 num_nodes++;
2775 }
2776 }
2777 return num_nodes;
2778 }
2780 size_t os::numa_get_leaf_groups(int *ids, size_t size) {
2781 size_t highest_node_number = Linux::numa_max_node();
2782 size_t i = 0;
2784 // Map all node ids in which is possible to allocate memory. Also nodes are
2785 // not always consecutively available, i.e. available from 0 to the highest
2786 // node number.
2787 for (size_t node = 0; node <= highest_node_number; node++) {
2788 if (Linux::isnode_in_configured_nodes(node)) {
2789 ids[i++] = node;
2790 }
2791 }
2792 return i;
2793 }
2795 bool os::get_page_info(char *start, page_info* info) {
2796 return false;
2797 }
2799 char *os::scan_pages(char *start, char* end, page_info* page_expected, page_info* page_found) {
2800 return end;
2801 }
2804 int os::Linux::sched_getcpu_syscall(void) {
2805 unsigned int cpu = 0;
2806 int retval = -1;
2808 #if defined(IA32)
2809 # ifndef SYS_getcpu
2810 # define SYS_getcpu 318
2811 # endif
2812 retval = syscall(SYS_getcpu, &cpu, NULL, NULL);
2813 #elif defined(AMD64)
2814 // Unfortunately we have to bring all these macros here from vsyscall.h
2815 // to be able to compile on old linuxes.
2816 # define __NR_vgetcpu 2
2817 # define VSYSCALL_START (-10UL << 20)
2818 # define VSYSCALL_SIZE 1024
2819 # define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr))
2820 typedef long (*vgetcpu_t)(unsigned int *cpu, unsigned int *node, unsigned long *tcache);
2821 vgetcpu_t vgetcpu = (vgetcpu_t)VSYSCALL_ADDR(__NR_vgetcpu);
2822 retval = vgetcpu(&cpu, NULL, NULL);
2823 #endif
2825 return (retval == -1) ? retval : cpu;
2826 }
2828 // Something to do with the numa-aware allocator needs these symbols
2829 extern "C" JNIEXPORT void numa_warn(int number, char *where, ...) { }
2830 extern "C" JNIEXPORT void numa_error(char *where) { }
2831 extern "C" JNIEXPORT int fork1() { return fork(); }
2833 // Handle request to load libnuma symbol version 1.1 (API v1). If it fails
2834 // load symbol from base version instead.
2835 void* os::Linux::libnuma_dlsym(void* handle, const char *name) {
2836 void *f = dlvsym(handle, name, "libnuma_1.1");
2837 if (f == NULL) {
2838 f = dlsym(handle, name);
2839 }
2840 return f;
2841 }
2843 // Handle request to load libnuma symbol version 1.2 (API v2) only.
2844 // Return NULL if the symbol is not defined in this particular version.
2845 void* os::Linux::libnuma_v2_dlsym(void* handle, const char* name) {
2846 return dlvsym(handle, name, "libnuma_1.2");
2847 }
2849 bool os::Linux::libnuma_init() {
2850 // sched_getcpu() should be in libc.
2851 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t,
2852 dlsym(RTLD_DEFAULT, "sched_getcpu")));
2854 // If it's not, try a direct syscall.
2855 if (sched_getcpu() == -1)
2856 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, (void*)&sched_getcpu_syscall));
2858 if (sched_getcpu() != -1) { // Does it work?
2859 void *handle = dlopen("libnuma.so.1", RTLD_LAZY);
2860 if (handle != NULL) {
2861 set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t,
2862 libnuma_dlsym(handle, "numa_node_to_cpus")));
2863 set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t,
2864 libnuma_dlsym(handle, "numa_max_node")));
2865 set_numa_num_configured_nodes(CAST_TO_FN_PTR(numa_num_configured_nodes_func_t,
2866 libnuma_dlsym(handle, "numa_num_configured_nodes")));
2867 set_numa_available(CAST_TO_FN_PTR(numa_available_func_t,
2868 libnuma_dlsym(handle, "numa_available")));
2869 set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t,
2870 libnuma_dlsym(handle, "numa_tonode_memory")));
2871 set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t,
2872 libnuma_dlsym(handle, "numa_interleave_memory")));
2873 set_numa_interleave_memory_v2(CAST_TO_FN_PTR(numa_interleave_memory_v2_func_t,
2874 libnuma_v2_dlsym(handle, "numa_interleave_memory")));
2875 set_numa_set_bind_policy(CAST_TO_FN_PTR(numa_set_bind_policy_func_t,
2876 libnuma_dlsym(handle, "numa_set_bind_policy")));
2877 set_numa_bitmask_isbitset(CAST_TO_FN_PTR(numa_bitmask_isbitset_func_t,
2878 libnuma_dlsym(handle, "numa_bitmask_isbitset")));
2879 set_numa_distance(CAST_TO_FN_PTR(numa_distance_func_t,
2880 libnuma_dlsym(handle, "numa_distance")));
2882 if (numa_available() != -1) {
2883 set_numa_all_nodes((unsigned long*)libnuma_dlsym(handle, "numa_all_nodes"));
2884 set_numa_all_nodes_ptr((struct bitmask **)libnuma_dlsym(handle, "numa_all_nodes_ptr"));
2885 set_numa_nodes_ptr((struct bitmask **)libnuma_dlsym(handle, "numa_nodes_ptr"));
2886 // Create an index -> node mapping, since nodes are not always consecutive
2887 _nindex_to_node = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<int>(0, true);
2888 rebuild_nindex_to_node_map();
2889 // Create a cpu -> node mapping
2890 _cpu_to_node = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<int>(0, true);
2891 rebuild_cpu_to_node_map();
2892 return true;
2893 }
2894 }
2895 }
2896 return false;
2897 }
2899 void os::Linux::rebuild_nindex_to_node_map() {
2900 int highest_node_number = Linux::numa_max_node();
2902 nindex_to_node()->clear();
2903 for (int node = 0; node <= highest_node_number; node++) {
2904 if (Linux::isnode_in_existing_nodes(node)) {
2905 nindex_to_node()->append(node);
2906 }
2907 }
2908 }
2910 // rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id.
2911 // The table is later used in get_node_by_cpu().
2912 void os::Linux::rebuild_cpu_to_node_map() {
2913 const size_t NCPUS = 32768; // Since the buffer size computation is very obscure
2914 // in libnuma (possible values are starting from 16,
2915 // and continuing up with every other power of 2, but less
2916 // than the maximum number of CPUs supported by kernel), and
2917 // is a subject to change (in libnuma version 2 the requirements
2918 // are more reasonable) we'll just hardcode the number they use
2919 // in the library.
2920 const size_t BitsPerCLong = sizeof(long) * CHAR_BIT;
2922 size_t cpu_num = processor_count();
2923 size_t cpu_map_size = NCPUS / BitsPerCLong;
2924 size_t cpu_map_valid_size =
2925 MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size);
2927 cpu_to_node()->clear();
2928 cpu_to_node()->at_grow(cpu_num - 1);
2930 size_t node_num = get_existing_num_nodes();
2932 int distance = 0;
2933 int closest_distance = INT_MAX;
2934 int closest_node = 0;
2935 unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size, mtInternal);
2936 for (size_t i = 0; i < node_num; i++) {
2937 // Check if node is configured (not a memory-less node). If it is not, find
2938 // the closest configured node.
2939 if (!isnode_in_configured_nodes(nindex_to_node()->at(i))) {
2940 closest_distance = INT_MAX;
2941 // Check distance from all remaining nodes in the system. Ignore distance
2942 // from itself and from another non-configured node.
2943 for (size_t m = 0; m < node_num; m++) {
2944 if (m != i && isnode_in_configured_nodes(nindex_to_node()->at(m))) {
2945 distance = numa_distance(nindex_to_node()->at(i), nindex_to_node()->at(m));
2946 // If a closest node is found, update. There is always at least one
2947 // configured node in the system so there is always at least one node
2948 // close.
2949 if (distance != 0 && distance < closest_distance) {
2950 closest_distance = distance;
2951 closest_node = nindex_to_node()->at(m);
2952 }
2953 }
2954 }
2955 } else {
2956 // Current node is already a configured node.
2957 closest_node = nindex_to_node()->at(i);
2958 }
2960 // Get cpus from the original node and map them to the closest node. If node
2961 // is a configured node (not a memory-less node), then original node and
2962 // closest node are the same.
2963 if (numa_node_to_cpus(nindex_to_node()->at(i), cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) {
2964 for (size_t j = 0; j < cpu_map_valid_size; j++) {
2965 if (cpu_map[j] != 0) {
2966 for (size_t k = 0; k < BitsPerCLong; k++) {
2967 if (cpu_map[j] & (1UL << k)) {
2968 cpu_to_node()->at_put(j * BitsPerCLong + k, closest_node);
2969 }
2970 }
2971 }
2972 }
2973 }
2974 }
2975 FREE_C_HEAP_ARRAY(unsigned long, cpu_map, mtInternal);
2976 }
2978 int os::Linux::get_node_by_cpu(int cpu_id) {
2979 if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) {
2980 return cpu_to_node()->at(cpu_id);
2981 }
2982 return -1;
2983 }
2985 GrowableArray<int>* os::Linux::_cpu_to_node;
2986 GrowableArray<int>* os::Linux::_nindex_to_node;
2987 os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu;
2988 os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus;
2989 os::Linux::numa_max_node_func_t os::Linux::_numa_max_node;
2990 os::Linux::numa_num_configured_nodes_func_t os::Linux::_numa_num_configured_nodes;
2991 os::Linux::numa_available_func_t os::Linux::_numa_available;
2992 os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory;
2993 os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory;
2994 os::Linux::numa_interleave_memory_v2_func_t os::Linux::_numa_interleave_memory_v2;
2995 os::Linux::numa_set_bind_policy_func_t os::Linux::_numa_set_bind_policy;
2996 os::Linux::numa_bitmask_isbitset_func_t os::Linux::_numa_bitmask_isbitset;
2997 os::Linux::numa_distance_func_t os::Linux::_numa_distance;
2998 unsigned long* os::Linux::_numa_all_nodes;
2999 struct bitmask* os::Linux::_numa_all_nodes_ptr;
3000 struct bitmask* os::Linux::_numa_nodes_ptr;
3002 bool os::pd_uncommit_memory(char* addr, size_t size) {
3003 uintptr_t res = (uintptr_t) ::mmap(addr, size, PROT_NONE,
3004 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0);
3005 return res != (uintptr_t) MAP_FAILED;
3006 }
3008 static
3009 address get_stack_commited_bottom(address bottom, size_t size) {
3010 address nbot = bottom;
3011 address ntop = bottom + size;
3013 size_t page_sz = os::vm_page_size();
3014 unsigned pages = size / page_sz;
3016 unsigned char vec[1];
3017 unsigned imin = 1, imax = pages + 1, imid;
3018 int mincore_return_value = 0;
3020 assert(imin <= imax, "Unexpected page size");
3022 while (imin < imax) {
3023 imid = (imax + imin) / 2;
3024 nbot = ntop - (imid * page_sz);
3026 // Use a trick with mincore to check whether the page is mapped or not.
3027 // mincore sets vec to 1 if page resides in memory and to 0 if page
3028 // is swapped output but if page we are asking for is unmapped
3029 // it returns -1,ENOMEM
3030 mincore_return_value = mincore(nbot, page_sz, vec);
3032 if (mincore_return_value == -1) {
3033 // Page is not mapped go up
3034 // to find first mapped page
3035 if (errno != EAGAIN) {
3036 assert(errno == ENOMEM, "Unexpected mincore errno");
3037 imax = imid;
3038 }
3039 } else {
3040 // Page is mapped go down
3041 // to find first not mapped page
3042 imin = imid + 1;
3043 }
3044 }
3046 nbot = nbot + page_sz;
3048 // Adjust stack bottom one page up if last checked page is not mapped
3049 if (mincore_return_value == -1) {
3050 nbot = nbot + page_sz;
3051 }
3053 return nbot;
3054 }
3057 // Linux uses a growable mapping for the stack, and if the mapping for
3058 // the stack guard pages is not removed when we detach a thread the
3059 // stack cannot grow beyond the pages where the stack guard was
3060 // mapped. If at some point later in the process the stack expands to
3061 // that point, the Linux kernel cannot expand the stack any further
3062 // because the guard pages are in the way, and a segfault occurs.
3063 //
3064 // However, it's essential not to split the stack region by unmapping
3065 // a region (leaving a hole) that's already part of the stack mapping,
3066 // so if the stack mapping has already grown beyond the guard pages at
3067 // the time we create them, we have to truncate the stack mapping.
3068 // So, we need to know the extent of the stack mapping when
3069 // create_stack_guard_pages() is called.
3071 // We only need this for stacks that are growable: at the time of
3072 // writing thread stacks don't use growable mappings (i.e. those
3073 // creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this
3074 // only applies to the main thread.
3076 // If the (growable) stack mapping already extends beyond the point
3077 // where we're going to put our guard pages, truncate the mapping at
3078 // that point by munmap()ping it. This ensures that when we later
3079 // munmap() the guard pages we don't leave a hole in the stack
3080 // mapping. This only affects the main/initial thread
3082 bool os::pd_create_stack_guard_pages(char* addr, size_t size) {
3084 if (os::Linux::is_initial_thread()) {
3085 // As we manually grow stack up to bottom inside create_attached_thread(),
3086 // it's likely that os::Linux::initial_thread_stack_bottom is mapped and
3087 // we don't need to do anything special.
3088 // Check it first, before calling heavy function.
3089 uintptr_t stack_extent = (uintptr_t) os::Linux::initial_thread_stack_bottom();
3090 unsigned char vec[1];
3092 if (mincore((address)stack_extent, os::vm_page_size(), vec) == -1) {
3093 // Fallback to slow path on all errors, including EAGAIN
3094 stack_extent = (uintptr_t) get_stack_commited_bottom(
3095 os::Linux::initial_thread_stack_bottom(),
3096 (size_t)addr - stack_extent);
3097 }
3099 if (stack_extent < (uintptr_t)addr) {
3100 ::munmap((void*)stack_extent, (uintptr_t)(addr - stack_extent));
3101 }
3102 }
3104 return os::commit_memory(addr, size, !ExecMem);
3105 }
3107 // If this is a growable mapping, remove the guard pages entirely by
3108 // munmap()ping them. If not, just call uncommit_memory(). This only
3109 // affects the main/initial thread, but guard against future OS changes
3110 // It's safe to always unmap guard pages for initial thread because we
3111 // always place it right after end of the mapped region
3113 bool os::remove_stack_guard_pages(char* addr, size_t size) {
3114 uintptr_t stack_extent, stack_base;
3116 if (os::Linux::is_initial_thread()) {
3117 return ::munmap(addr, size) == 0;
3118 }
3120 return os::uncommit_memory(addr, size);
3121 }
3123 static address _highest_vm_reserved_address = NULL;
3125 // If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory
3126 // at 'requested_addr'. If there are existing memory mappings at the same
3127 // location, however, they will be overwritten. If 'fixed' is false,
3128 // 'requested_addr' is only treated as a hint, the return value may or
3129 // may not start from the requested address. Unlike Linux mmap(), this
3130 // function returns NULL to indicate failure.
3131 static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) {
3132 char * addr;
3133 int flags;
3135 flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS;
3136 if (fixed) {
3137 assert((uintptr_t)requested_addr % os::Linux::page_size() == 0, "unaligned address");
3138 flags |= MAP_FIXED;
3139 }
3141 // Map reserved/uncommitted pages PROT_NONE so we fail early if we
3142 // touch an uncommitted page. Otherwise, the read/write might
3143 // succeed if we have enough swap space to back the physical page.
3144 addr = (char*)::mmap(requested_addr, bytes, PROT_NONE,
3145 flags, -1, 0);
3147 if (addr != MAP_FAILED) {
3148 // anon_mmap() should only get called during VM initialization,
3149 // don't need lock (actually we can skip locking even it can be called
3150 // from multiple threads, because _highest_vm_reserved_address is just a
3151 // hint about the upper limit of non-stack memory regions.)
3152 if ((address)addr + bytes > _highest_vm_reserved_address) {
3153 _highest_vm_reserved_address = (address)addr + bytes;
3154 }
3155 }
3157 return addr == MAP_FAILED ? NULL : addr;
3158 }
3160 // Allocate (using mmap, NO_RESERVE, with small pages) at either a given request address
3161 // (req_addr != NULL) or with a given alignment.
3162 // - bytes shall be a multiple of alignment.
3163 // - req_addr can be NULL. If not NULL, it must be a multiple of alignment.
3164 // - alignment sets the alignment at which memory shall be allocated.
3165 // It must be a multiple of allocation granularity.
3166 // Returns address of memory or NULL. If req_addr was not NULL, will only return
3167 // req_addr or NULL.
3168 static char* anon_mmap_aligned(size_t bytes, size_t alignment, char* req_addr) {
3170 size_t extra_size = bytes;
3171 if (req_addr == NULL && alignment > 0) {
3172 extra_size += alignment;
3173 }
3175 char* start = (char*) ::mmap(req_addr, extra_size, PROT_NONE,
3176 MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE,
3177 -1, 0);
3178 if (start == MAP_FAILED) {
3179 start = NULL;
3180 } else {
3181 if (req_addr != NULL) {
3182 if (start != req_addr) {
3183 ::munmap(start, extra_size);
3184 start = NULL;
3185 }
3186 } else {
3187 char* const start_aligned = (char*) align_ptr_up(start, alignment);
3188 char* const end_aligned = start_aligned + bytes;
3189 char* const end = start + extra_size;
3190 if (start_aligned > start) {
3191 ::munmap(start, start_aligned - start);
3192 }
3193 if (end_aligned < end) {
3194 ::munmap(end_aligned, end - end_aligned);
3195 }
3196 start = start_aligned;
3197 }
3198 }
3199 return start;
3200 }
3202 // Don't update _highest_vm_reserved_address, because there might be memory
3203 // regions above addr + size. If so, releasing a memory region only creates
3204 // a hole in the address space, it doesn't help prevent heap-stack collision.
3205 //
3206 static int anon_munmap(char * addr, size_t size) {
3207 return ::munmap(addr, size) == 0;
3208 }
3210 char* os::pd_reserve_memory(size_t bytes, char* requested_addr,
3211 size_t alignment_hint) {
3212 return anon_mmap(requested_addr, bytes, (requested_addr != NULL));
3213 }
3215 bool os::pd_release_memory(char* addr, size_t size) {
3216 return anon_munmap(addr, size);
3217 }
3219 static address highest_vm_reserved_address() {
3220 return _highest_vm_reserved_address;
3221 }
3223 static bool linux_mprotect(char* addr, size_t size, int prot) {
3224 // Linux wants the mprotect address argument to be page aligned.
3225 char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::page_size());
3227 // According to SUSv3, mprotect() should only be used with mappings
3228 // established by mmap(), and mmap() always maps whole pages. Unaligned
3229 // 'addr' likely indicates problem in the VM (e.g. trying to change
3230 // protection of malloc'ed or statically allocated memory). Check the
3231 // caller if you hit this assert.
3232 assert(addr == bottom, "sanity check");
3234 size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Linux::page_size());
3235 return ::mprotect(bottom, size, prot) == 0;
3236 }
3238 // Set protections specified
3239 bool os::protect_memory(char* addr, size_t bytes, ProtType prot,
3240 bool is_committed) {
3241 unsigned int p = 0;
3242 switch (prot) {
3243 case MEM_PROT_NONE: p = PROT_NONE; break;
3244 case MEM_PROT_READ: p = PROT_READ; break;
3245 case MEM_PROT_RW: p = PROT_READ|PROT_WRITE; break;
3246 case MEM_PROT_RWX: p = PROT_READ|PROT_WRITE|PROT_EXEC; break;
3247 default:
3248 ShouldNotReachHere();
3249 }
3250 // is_committed is unused.
3251 return linux_mprotect(addr, bytes, p);
3252 }
3254 bool os::guard_memory(char* addr, size_t size) {
3255 return linux_mprotect(addr, size, PROT_NONE);
3256 }
3258 bool os::unguard_memory(char* addr, size_t size) {
3259 return linux_mprotect(addr, size, PROT_READ|PROT_WRITE);
3260 }
3262 bool os::Linux::transparent_huge_pages_sanity_check(bool warn, size_t page_size) {
3263 bool result = false;
3264 void *p = mmap(NULL, page_size * 2, PROT_READ|PROT_WRITE,
3265 MAP_ANONYMOUS|MAP_PRIVATE,
3266 -1, 0);
3267 if (p != MAP_FAILED) {
3268 void *aligned_p = align_ptr_up(p, page_size);
3270 result = madvise(aligned_p, page_size, MADV_HUGEPAGE) == 0;
3272 munmap(p, page_size * 2);
3273 }
3275 if (warn && !result) {
3276 warning("TransparentHugePages is not supported by the operating system.");
3277 }
3279 return result;
3280 }
3282 bool os::Linux::hugetlbfs_sanity_check(bool warn, size_t page_size) {
3283 bool result = false;
3284 void *p = mmap(NULL, page_size, PROT_READ|PROT_WRITE,
3285 MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB,
3286 -1, 0);
3288 if (p != MAP_FAILED) {
3289 // We don't know if this really is a huge page or not.
3290 FILE *fp = fopen("/proc/self/maps", "r");
3291 if (fp) {
3292 while (!feof(fp)) {
3293 char chars[257];
3294 long x = 0;
3295 if (fgets(chars, sizeof(chars), fp)) {
3296 if (sscanf(chars, "%lx-%*x", &x) == 1
3297 && x == (long)p) {
3298 if (strstr (chars, "hugepage")) {
3299 result = true;
3300 break;
3301 }
3302 }
3303 }
3304 }
3305 fclose(fp);
3306 }
3307 munmap(p, page_size);
3308 }
3310 if (warn && !result) {
3311 warning("HugeTLBFS is not supported by the operating system.");
3312 }
3314 return result;
3315 }
3317 /*
3318 * Set the coredump_filter bits to include largepages in core dump (bit 6)
3319 *
3320 * From the coredump_filter documentation:
3321 *
3322 * - (bit 0) anonymous private memory
3323 * - (bit 1) anonymous shared memory
3324 * - (bit 2) file-backed private memory
3325 * - (bit 3) file-backed shared memory
3326 * - (bit 4) ELF header pages in file-backed private memory areas (it is
3327 * effective only if the bit 2 is cleared)
3328 * - (bit 5) hugetlb private memory
3329 * - (bit 6) hugetlb shared memory
3330 */
3331 static void set_coredump_filter(void) {
3332 FILE *f;
3333 long cdm;
3335 if ((f = fopen("/proc/self/coredump_filter", "r+")) == NULL) {
3336 return;
3337 }
3339 if (fscanf(f, "%lx", &cdm) != 1) {
3340 fclose(f);
3341 return;
3342 }
3344 rewind(f);
3346 if ((cdm & LARGEPAGES_BIT) == 0) {
3347 cdm |= LARGEPAGES_BIT;
3348 fprintf(f, "%#lx", cdm);
3349 }
3351 fclose(f);
3352 }
3354 // Large page support
3356 static size_t _large_page_size = 0;
3358 size_t os::Linux::find_large_page_size() {
3359 size_t large_page_size = 0;
3361 // large_page_size on Linux is used to round up heap size. x86 uses either
3362 // 2M or 4M page, depending on whether PAE (Physical Address Extensions)
3363 // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use
3364 // page as large as 256M.
3365 //
3366 // Here we try to figure out page size by parsing /proc/meminfo and looking
3367 // for a line with the following format:
3368 // Hugepagesize: 2048 kB
3369 //
3370 // If we can't determine the value (e.g. /proc is not mounted, or the text
3371 // format has been changed), we'll use the largest page size supported by
3372 // the processor.
3374 #ifndef ZERO
3375 large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M)
3376 ARM_ONLY(2 * M) PPC_ONLY(4 * M) MIPS64_ONLY(4 * M); //In MIPS _large_page_size is seted 4*M.
3377 #endif // ZERO
3379 FILE *fp = fopen("/proc/meminfo", "r");
3380 if (fp) {
3381 while (!feof(fp)) {
3382 int x = 0;
3383 char buf[16];
3384 if (fscanf(fp, "Hugepagesize: %d", &x) == 1) {
3385 if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) {
3386 large_page_size = x * K;
3387 break;
3388 }
3389 } else {
3390 // skip to next line
3391 for (;;) {
3392 int ch = fgetc(fp);
3393 if (ch == EOF || ch == (int)'\n') break;
3394 }
3395 }
3396 }
3397 fclose(fp);
3398 }
3400 if (!FLAG_IS_DEFAULT(LargePageSizeInBytes) && LargePageSizeInBytes != large_page_size) {
3401 warning("Setting LargePageSizeInBytes has no effect on this OS. Large page size is "
3402 SIZE_FORMAT "%s.", byte_size_in_proper_unit(large_page_size),
3403 proper_unit_for_byte_size(large_page_size));
3404 }
3406 return large_page_size;
3407 }
3409 size_t os::Linux::setup_large_page_size() {
3410 _large_page_size = Linux::find_large_page_size();
3411 const size_t default_page_size = (size_t)Linux::page_size();
3412 if (_large_page_size > default_page_size) {
3413 _page_sizes[0] = _large_page_size;
3414 _page_sizes[1] = default_page_size;
3415 _page_sizes[2] = 0;
3416 }
3418 return _large_page_size;
3419 }
3421 bool os::Linux::setup_large_page_type(size_t page_size) {
3422 if (FLAG_IS_DEFAULT(UseHugeTLBFS) &&
3423 FLAG_IS_DEFAULT(UseSHM) &&
3424 FLAG_IS_DEFAULT(UseTransparentHugePages)) {
3426 // The type of large pages has not been specified by the user.
3428 // Try UseHugeTLBFS and then UseSHM.
3429 UseHugeTLBFS = UseSHM = true;
3431 // Don't try UseTransparentHugePages since there are known
3432 // performance issues with it turned on. This might change in the future.
3433 UseTransparentHugePages = false;
3434 }
3436 if (UseTransparentHugePages) {
3437 bool warn_on_failure = !FLAG_IS_DEFAULT(UseTransparentHugePages);
3438 if (transparent_huge_pages_sanity_check(warn_on_failure, page_size)) {
3439 UseHugeTLBFS = false;
3440 UseSHM = false;
3441 return true;
3442 }
3443 UseTransparentHugePages = false;
3444 }
3446 if (UseHugeTLBFS) {
3447 bool warn_on_failure = !FLAG_IS_DEFAULT(UseHugeTLBFS);
3448 if (hugetlbfs_sanity_check(warn_on_failure, page_size)) {
3449 UseSHM = false;
3450 return true;
3451 }
3452 UseHugeTLBFS = false;
3453 }
3455 return UseSHM;
3456 }
3458 void os::large_page_init() {
3459 if (!UseLargePages &&
3460 !UseTransparentHugePages &&
3461 !UseHugeTLBFS &&
3462 !UseSHM) {
3463 // Not using large pages.
3464 return;
3465 }
3467 if (!FLAG_IS_DEFAULT(UseLargePages) && !UseLargePages) {
3468 // The user explicitly turned off large pages.
3469 // Ignore the rest of the large pages flags.
3470 UseTransparentHugePages = false;
3471 UseHugeTLBFS = false;
3472 UseSHM = false;
3473 return;
3474 }
3476 size_t large_page_size = Linux::setup_large_page_size();
3477 UseLargePages = Linux::setup_large_page_type(large_page_size);
3479 set_coredump_filter();
3480 }
3482 #ifndef SHM_HUGETLB
3483 #define SHM_HUGETLB 04000
3484 #endif
3486 #define shm_warning_format(format, ...) \
3487 do { \
3488 if (UseLargePages && \
3489 (!FLAG_IS_DEFAULT(UseLargePages) || \
3490 !FLAG_IS_DEFAULT(UseSHM) || \
3491 !FLAG_IS_DEFAULT(LargePageSizeInBytes))) { \
3492 warning(format, __VA_ARGS__); \
3493 } \
3494 } while (0)
3496 #define shm_warning(str) shm_warning_format("%s", str)
3498 #define shm_warning_with_errno(str) \
3499 do { \
3500 int err = errno; \
3501 shm_warning_format(str " (error = %d)", err); \
3502 } while (0)
3504 static char* shmat_with_alignment(int shmid, size_t bytes, size_t alignment) {
3505 assert(is_size_aligned(bytes, alignment), "Must be divisible by the alignment");
3507 if (!is_size_aligned(alignment, SHMLBA)) {
3508 assert(false, "Code below assumes that alignment is at least SHMLBA aligned");
3509 return NULL;
3510 }
3512 // To ensure that we get 'alignment' aligned memory from shmat,
3513 // we pre-reserve aligned virtual memory and then attach to that.
3515 char* pre_reserved_addr = anon_mmap_aligned(bytes, alignment, NULL);
3516 if (pre_reserved_addr == NULL) {
3517 // Couldn't pre-reserve aligned memory.
3518 shm_warning("Failed to pre-reserve aligned memory for shmat.");
3519 return NULL;
3520 }
3522 // SHM_REMAP is needed to allow shmat to map over an existing mapping.
3523 char* addr = (char*)shmat(shmid, pre_reserved_addr, SHM_REMAP);
3525 if ((intptr_t)addr == -1) {
3526 int err = errno;
3527 shm_warning_with_errno("Failed to attach shared memory.");
3529 assert(err != EACCES, "Unexpected error");
3530 assert(err != EIDRM, "Unexpected error");
3531 assert(err != EINVAL, "Unexpected error");
3533 // Since we don't know if the kernel unmapped the pre-reserved memory area
3534 // we can't unmap it, since that would potentially unmap memory that was
3535 // mapped from other threads.
3536 return NULL;
3537 }
3539 return addr;
3540 }
3542 static char* shmat_at_address(int shmid, char* req_addr) {
3543 if (!is_ptr_aligned(req_addr, SHMLBA)) {
3544 assert(false, "Requested address needs to be SHMLBA aligned");
3545 return NULL;
3546 }
3548 char* addr = (char*)shmat(shmid, req_addr, 0);
3550 if ((intptr_t)addr == -1) {
3551 shm_warning_with_errno("Failed to attach shared memory.");
3552 return NULL;
3553 }
3555 return addr;
3556 }
3558 static char* shmat_large_pages(int shmid, size_t bytes, size_t alignment, char* req_addr) {
3559 // If a req_addr has been provided, we assume that the caller has already aligned the address.
3560 if (req_addr != NULL) {
3561 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Must be divisible by the large page size");
3562 assert(is_ptr_aligned(req_addr, alignment), "Must be divisible by given alignment");
3563 return shmat_at_address(shmid, req_addr);
3564 }
3566 // Since shmid has been setup with SHM_HUGETLB, shmat will automatically
3567 // return large page size aligned memory addresses when req_addr == NULL.
3568 // However, if the alignment is larger than the large page size, we have
3569 // to manually ensure that the memory returned is 'alignment' aligned.
3570 if (alignment > os::large_page_size()) {
3571 assert(is_size_aligned(alignment, os::large_page_size()), "Must be divisible by the large page size");
3572 return shmat_with_alignment(shmid, bytes, alignment);
3573 } else {
3574 return shmat_at_address(shmid, NULL);
3575 }
3576 }
3578 char* os::Linux::reserve_memory_special_shm(size_t bytes, size_t alignment, char* req_addr, bool exec) {
3579 // "exec" is passed in but not used. Creating the shared image for
3580 // the code cache doesn't have an SHM_X executable permission to check.
3581 assert(UseLargePages && UseSHM, "only for SHM large pages");
3582 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address");
3583 assert(is_ptr_aligned(req_addr, alignment), "Unaligned address");
3585 if (!is_size_aligned(bytes, os::large_page_size())) {
3586 return NULL; // Fallback to small pages.
3587 }
3589 // Create a large shared memory region to attach to based on size.
3590 // Currently, size is the total size of the heap.
3591 int shmid = shmget(IPC_PRIVATE, bytes, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W);
3592 if (shmid == -1) {
3593 // Possible reasons for shmget failure:
3594 // 1. shmmax is too small for Java heap.
3595 // > check shmmax value: cat /proc/sys/kernel/shmmax
3596 // > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax
3597 // 2. not enough large page memory.
3598 // > check available large pages: cat /proc/meminfo
3599 // > increase amount of large pages:
3600 // echo new_value > /proc/sys/vm/nr_hugepages
3601 // Note 1: different Linux may use different name for this property,
3602 // e.g. on Redhat AS-3 it is "hugetlb_pool".
3603 // Note 2: it's possible there's enough physical memory available but
3604 // they are so fragmented after a long run that they can't
3605 // coalesce into large pages. Try to reserve large pages when
3606 // the system is still "fresh".
3607 shm_warning_with_errno("Failed to reserve shared memory.");
3608 return NULL;
3609 }
3611 // Attach to the region.
3612 char* addr = shmat_large_pages(shmid, bytes, alignment, req_addr);
3614 // Remove shmid. If shmat() is successful, the actual shared memory segment
3615 // will be deleted when it's detached by shmdt() or when the process
3616 // terminates. If shmat() is not successful this will remove the shared
3617 // segment immediately.
3618 shmctl(shmid, IPC_RMID, NULL);
3620 return addr;
3621 }
3623 static void warn_on_large_pages_failure(char* req_addr, size_t bytes, int error) {
3624 assert(error == ENOMEM, "Only expect to fail if no memory is available");
3626 bool warn_on_failure = UseLargePages &&
3627 (!FLAG_IS_DEFAULT(UseLargePages) ||
3628 !FLAG_IS_DEFAULT(UseHugeTLBFS) ||
3629 !FLAG_IS_DEFAULT(LargePageSizeInBytes));
3631 if (warn_on_failure) {
3632 char msg[128];
3633 jio_snprintf(msg, sizeof(msg), "Failed to reserve large pages memory req_addr: "
3634 PTR_FORMAT " bytes: " SIZE_FORMAT " (errno = %d).", req_addr, bytes, error);
3635 warning("%s", msg);
3636 }
3637 }
3639 char* os::Linux::reserve_memory_special_huge_tlbfs_only(size_t bytes, char* req_addr, bool exec) {
3640 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages");
3641 assert(is_size_aligned(bytes, os::large_page_size()), "Unaligned size");
3642 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address");
3644 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
3645 char* addr = (char*)::mmap(req_addr, bytes, prot,
3646 MAP_PRIVATE|MAP_ANONYMOUS|MAP_HUGETLB,
3647 -1, 0);
3649 if (addr == MAP_FAILED) {
3650 warn_on_large_pages_failure(req_addr, bytes, errno);
3651 return NULL;
3652 }
3654 assert(is_ptr_aligned(addr, os::large_page_size()), "Must be");
3656 return addr;
3657 }
3659 // Reserve memory using mmap(MAP_HUGETLB).
3660 // - bytes shall be a multiple of alignment.
3661 // - req_addr can be NULL. If not NULL, it must be a multiple of alignment.
3662 // - alignment sets the alignment at which memory shall be allocated.
3663 // It must be a multiple of allocation granularity.
3664 // Returns address of memory or NULL. If req_addr was not NULL, will only return
3665 // req_addr or NULL.
3666 char* os::Linux::reserve_memory_special_huge_tlbfs_mixed(size_t bytes, size_t alignment, char* req_addr, bool exec) {
3667 size_t large_page_size = os::large_page_size();
3668 assert(bytes >= large_page_size, "Shouldn't allocate large pages for small sizes");
3670 assert(is_ptr_aligned(req_addr, alignment), "Must be");
3671 assert(is_size_aligned(bytes, alignment), "Must be");
3673 // First reserve - but not commit - the address range in small pages.
3674 char* const start = anon_mmap_aligned(bytes, alignment, req_addr);
3676 if (start == NULL) {
3677 return NULL;
3678 }
3680 assert(is_ptr_aligned(start, alignment), "Must be");
3682 char* end = start + bytes;
3684 // Find the regions of the allocated chunk that can be promoted to large pages.
3685 char* lp_start = (char*)align_ptr_up(start, large_page_size);
3686 char* lp_end = (char*)align_ptr_down(end, large_page_size);
3688 size_t lp_bytes = lp_end - lp_start;
3690 assert(is_size_aligned(lp_bytes, large_page_size), "Must be");
3692 if (lp_bytes == 0) {
3693 // The mapped region doesn't even span the start and the end of a large page.
3694 // Fall back to allocate a non-special area.
3695 ::munmap(start, end - start);
3696 return NULL;
3697 }
3699 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
3701 void* result;
3703 // Commit small-paged leading area.
3704 if (start != lp_start) {
3705 result = ::mmap(start, lp_start - start, prot,
3706 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED,
3707 -1, 0);
3708 if (result == MAP_FAILED) {
3709 ::munmap(lp_start, end - lp_start);
3710 return NULL;
3711 }
3712 }
3714 // Commit large-paged area.
3715 result = ::mmap(lp_start, lp_bytes, prot,
3716 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED|MAP_HUGETLB,
3717 -1, 0);
3718 if (result == MAP_FAILED) {
3719 warn_on_large_pages_failure(lp_start, lp_bytes, errno);
3720 // If the mmap above fails, the large pages region will be unmapped and we
3721 // have regions before and after with small pages. Release these regions.
3722 //
3723 // | mapped | unmapped | mapped |
3724 // ^ ^ ^ ^
3725 // start lp_start lp_end end
3726 //
3727 ::munmap(start, lp_start - start);
3728 ::munmap(lp_end, end - lp_end);
3729 return NULL;
3730 }
3732 // Commit small-paged trailing area.
3733 if (lp_end != end) {
3734 result = ::mmap(lp_end, end - lp_end, prot,
3735 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED,
3736 -1, 0);
3737 if (result == MAP_FAILED) {
3738 ::munmap(start, lp_end - start);
3739 return NULL;
3740 }
3741 }
3743 return start;
3744 }
3746 char* os::Linux::reserve_memory_special_huge_tlbfs(size_t bytes, size_t alignment, char* req_addr, bool exec) {
3747 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages");
3748 assert(is_ptr_aligned(req_addr, alignment), "Must be");
3749 assert(is_size_aligned(alignment, os::vm_allocation_granularity()), "Must be");
3750 assert(is_power_of_2(os::large_page_size()), "Must be");
3751 assert(bytes >= os::large_page_size(), "Shouldn't allocate large pages for small sizes");
3753 if (is_size_aligned(bytes, os::large_page_size()) && alignment <= os::large_page_size()) {
3754 return reserve_memory_special_huge_tlbfs_only(bytes, req_addr, exec);
3755 } else {
3756 return reserve_memory_special_huge_tlbfs_mixed(bytes, alignment, req_addr, exec);
3757 }
3758 }
3760 char* os::reserve_memory_special(size_t bytes, size_t alignment, char* req_addr, bool exec) {
3761 assert(UseLargePages, "only for large pages");
3763 char* addr;
3764 if (UseSHM) {
3765 addr = os::Linux::reserve_memory_special_shm(bytes, alignment, req_addr, exec);
3766 } else {
3767 assert(UseHugeTLBFS, "must be");
3768 addr = os::Linux::reserve_memory_special_huge_tlbfs(bytes, alignment, req_addr, exec);
3769 }
3771 if (addr != NULL) {
3772 if (UseNUMAInterleaving) {
3773 numa_make_global(addr, bytes);
3774 }
3776 // The memory is committed
3777 MemTracker::record_virtual_memory_reserve_and_commit((address)addr, bytes, CALLER_PC);
3778 }
3780 return addr;
3781 }
3783 bool os::Linux::release_memory_special_shm(char* base, size_t bytes) {
3784 // detaching the SHM segment will also delete it, see reserve_memory_special_shm()
3785 return shmdt(base) == 0;
3786 }
3788 bool os::Linux::release_memory_special_huge_tlbfs(char* base, size_t bytes) {
3789 return pd_release_memory(base, bytes);
3790 }
3792 bool os::release_memory_special(char* base, size_t bytes) {
3793 bool res;
3794 if (MemTracker::tracking_level() > NMT_minimal) {
3795 Tracker tkr = MemTracker::get_virtual_memory_release_tracker();
3796 res = os::Linux::release_memory_special_impl(base, bytes);
3797 if (res) {
3798 tkr.record((address)base, bytes);
3799 }
3801 } else {
3802 res = os::Linux::release_memory_special_impl(base, bytes);
3803 }
3804 return res;
3805 }
3807 bool os::Linux::release_memory_special_impl(char* base, size_t bytes) {
3808 assert(UseLargePages, "only for large pages");
3809 bool res;
3811 if (UseSHM) {
3812 res = os::Linux::release_memory_special_shm(base, bytes);
3813 } else {
3814 assert(UseHugeTLBFS, "must be");
3815 res = os::Linux::release_memory_special_huge_tlbfs(base, bytes);
3816 }
3817 return res;
3818 }
3820 size_t os::large_page_size() {
3821 return _large_page_size;
3822 }
3824 // With SysV SHM the entire memory region must be allocated as shared
3825 // memory.
3826 // HugeTLBFS allows application to commit large page memory on demand.
3827 // However, when committing memory with HugeTLBFS fails, the region
3828 // that was supposed to be committed will lose the old reservation
3829 // and allow other threads to steal that memory region. Because of this
3830 // behavior we can't commit HugeTLBFS memory.
3831 bool os::can_commit_large_page_memory() {
3832 return UseTransparentHugePages;
3833 }
3835 bool os::can_execute_large_page_memory() {
3836 return UseTransparentHugePages || UseHugeTLBFS;
3837 }
3839 // Reserve memory at an arbitrary address, only if that area is
3840 // available (and not reserved for something else).
3842 char* os::pd_attempt_reserve_memory_at(size_t bytes, char* requested_addr) {
3843 const int max_tries = 10;
3844 char* base[max_tries];
3845 size_t size[max_tries];
3846 const size_t gap = 0x000000;
3848 // Assert only that the size is a multiple of the page size, since
3849 // that's all that mmap requires, and since that's all we really know
3850 // about at this low abstraction level. If we need higher alignment,
3851 // we can either pass an alignment to this method or verify alignment
3852 // in one of the methods further up the call chain. See bug 5044738.
3853 assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block");
3855 // Repeatedly allocate blocks until the block is allocated at the
3856 // right spot. Give up after max_tries. Note that reserve_memory() will
3857 // automatically update _highest_vm_reserved_address if the call is
3858 // successful. The variable tracks the highest memory address every reserved
3859 // by JVM. It is used to detect heap-stack collision if running with
3860 // fixed-stack LinuxThreads. Because here we may attempt to reserve more
3861 // space than needed, it could confuse the collision detecting code. To
3862 // solve the problem, save current _highest_vm_reserved_address and
3863 // calculate the correct value before return.
3864 address old_highest = _highest_vm_reserved_address;
3866 // Linux mmap allows caller to pass an address as hint; give it a try first,
3867 // if kernel honors the hint then we can return immediately.
3868 char * addr = anon_mmap(requested_addr, bytes, false);
3869 if (addr == requested_addr) {
3870 return requested_addr;
3871 }
3873 if (addr != NULL) {
3874 // mmap() is successful but it fails to reserve at the requested address
3875 anon_munmap(addr, bytes);
3876 }
3878 int i;
3879 for (i = 0; i < max_tries; ++i) {
3880 base[i] = reserve_memory(bytes);
3882 if (base[i] != NULL) {
3883 // Is this the block we wanted?
3884 if (base[i] == requested_addr) {
3885 size[i] = bytes;
3886 break;
3887 }
3889 // Does this overlap the block we wanted? Give back the overlapped
3890 // parts and try again.
3892 size_t top_overlap = requested_addr + (bytes + gap) - base[i];
3893 if (top_overlap >= 0 && top_overlap < bytes) {
3894 unmap_memory(base[i], top_overlap);
3895 base[i] += top_overlap;
3896 size[i] = bytes - top_overlap;
3897 } else {
3898 size_t bottom_overlap = base[i] + bytes - requested_addr;
3899 if (bottom_overlap >= 0 && bottom_overlap < bytes) {
3900 unmap_memory(requested_addr, bottom_overlap);
3901 size[i] = bytes - bottom_overlap;
3902 } else {
3903 size[i] = bytes;
3904 }
3905 }
3906 }
3907 }
3909 // Give back the unused reserved pieces.
3911 for (int j = 0; j < i; ++j) {
3912 if (base[j] != NULL) {
3913 unmap_memory(base[j], size[j]);
3914 }
3915 }
3917 if (i < max_tries) {
3918 _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes);
3919 return requested_addr;
3920 } else {
3921 _highest_vm_reserved_address = old_highest;
3922 return NULL;
3923 }
3924 }
3926 size_t os::read(int fd, void *buf, unsigned int nBytes) {
3927 return ::read(fd, buf, nBytes);
3928 }
3930 // TODO-FIXME: reconcile Solaris' os::sleep with the linux variation.
3931 // Solaris uses poll(), linux uses park().
3932 // Poll() is likely a better choice, assuming that Thread.interrupt()
3933 // generates a SIGUSRx signal. Note that SIGUSR1 can interfere with
3934 // SIGSEGV, see 4355769.
3936 int os::sleep(Thread* thread, jlong millis, bool interruptible) {
3937 assert(thread == Thread::current(), "thread consistency check");
3939 ParkEvent * const slp = thread->_SleepEvent ;
3940 slp->reset() ;
3941 OrderAccess::fence() ;
3943 if (interruptible) {
3944 jlong prevtime = javaTimeNanos();
3946 for (;;) {
3947 if (os::is_interrupted(thread, true)) {
3948 return OS_INTRPT;
3949 }
3951 jlong newtime = javaTimeNanos();
3953 if (newtime - prevtime < 0) {
3954 // time moving backwards, should only happen if no monotonic clock
3955 // not a guarantee() because JVM should not abort on kernel/glibc bugs
3956 assert(!Linux::supports_monotonic_clock(), "time moving backwards");
3957 } else {
3958 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC;
3959 }
3961 if(millis <= 0) {
3962 return OS_OK;
3963 }
3965 prevtime = newtime;
3967 {
3968 assert(thread->is_Java_thread(), "sanity check");
3969 JavaThread *jt = (JavaThread *) thread;
3970 ThreadBlockInVM tbivm(jt);
3971 OSThreadWaitState osts(jt->osthread(), false /* not Object.wait() */);
3973 jt->set_suspend_equivalent();
3974 // cleared by handle_special_suspend_equivalent_condition() or
3975 // java_suspend_self() via check_and_wait_while_suspended()
3977 slp->park(millis);
3979 // were we externally suspended while we were waiting?
3980 jt->check_and_wait_while_suspended();
3981 }
3982 }
3983 } else {
3984 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */);
3985 jlong prevtime = javaTimeNanos();
3987 for (;;) {
3988 // It'd be nice to avoid the back-to-back javaTimeNanos() calls on
3989 // the 1st iteration ...
3990 jlong newtime = javaTimeNanos();
3992 if (newtime - prevtime < 0) {
3993 // time moving backwards, should only happen if no monotonic clock
3994 // not a guarantee() because JVM should not abort on kernel/glibc bugs
3995 assert(!Linux::supports_monotonic_clock(), "time moving backwards");
3996 } else {
3997 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC;
3998 }
4000 if(millis <= 0) break ;
4002 prevtime = newtime;
4003 slp->park(millis);
4004 }
4005 return OS_OK ;
4006 }
4007 }
4009 //
4010 // Short sleep, direct OS call.
4011 //
4012 // Note: certain versions of Linux CFS scheduler (since 2.6.23) do not guarantee
4013 // sched_yield(2) will actually give up the CPU:
4014 //
4015 // * Alone on this pariticular CPU, keeps running.
4016 // * Before the introduction of "skip_buddy" with "compat_yield" disabled
4017 // (pre 2.6.39).
4018 //
4019 // So calling this with 0 is an alternative.
4020 //
4021 void os::naked_short_sleep(jlong ms) {
4022 struct timespec req;
4024 assert(ms < 1000, "Un-interruptable sleep, short time use only");
4025 req.tv_sec = 0;
4026 if (ms > 0) {
4027 req.tv_nsec = (ms % 1000) * 1000000;
4028 }
4029 else {
4030 req.tv_nsec = 1;
4031 }
4033 nanosleep(&req, NULL);
4035 return;
4036 }
4038 // Sleep forever; naked call to OS-specific sleep; use with CAUTION
4039 void os::infinite_sleep() {
4040 while (true) { // sleep forever ...
4041 ::sleep(100); // ... 100 seconds at a time
4042 }
4043 }
4045 // Used to convert frequent JVM_Yield() to nops
4046 bool os::dont_yield() {
4047 return DontYieldALot;
4048 }
4050 void os::yield() {
4051 sched_yield();
4052 }
4054 os::YieldResult os::NakedYield() { sched_yield(); return os::YIELD_UNKNOWN ;}
4056 void os::yield_all(int attempts) {
4057 // Yields to all threads, including threads with lower priorities
4058 // Threads on Linux are all with same priority. The Solaris style
4059 // os::yield_all() with nanosleep(1ms) is not necessary.
4060 sched_yield();
4061 }
4063 // Called from the tight loops to possibly influence time-sharing heuristics
4064 void os::loop_breaker(int attempts) {
4065 os::yield_all(attempts);
4066 }
4068 ////////////////////////////////////////////////////////////////////////////////
4069 // thread priority support
4071 // Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER
4072 // only supports dynamic priority, static priority must be zero. For real-time
4073 // applications, Linux supports SCHED_RR which allows static priority (1-99).
4074 // However, for large multi-threaded applications, SCHED_RR is not only slower
4075 // than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out
4076 // of 5 runs - Sep 2005).
4077 //
4078 // The following code actually changes the niceness of kernel-thread/LWP. It
4079 // has an assumption that setpriority() only modifies one kernel-thread/LWP,
4080 // not the entire user process, and user level threads are 1:1 mapped to kernel
4081 // threads. It has always been the case, but could change in the future. For
4082 // this reason, the code should not be used as default (ThreadPriorityPolicy=0).
4083 // It is only used when ThreadPriorityPolicy=1 and requires root privilege.
4085 int os::java_to_os_priority[CriticalPriority + 1] = {
4086 19, // 0 Entry should never be used
4088 4, // 1 MinPriority
4089 3, // 2
4090 2, // 3
4092 1, // 4
4093 0, // 5 NormPriority
4094 -1, // 6
4096 -2, // 7
4097 -3, // 8
4098 -4, // 9 NearMaxPriority
4100 -5, // 10 MaxPriority
4102 -5 // 11 CriticalPriority
4103 };
4105 static int prio_init() {
4106 if (ThreadPriorityPolicy == 1) {
4107 // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1
4108 // if effective uid is not root. Perhaps, a more elegant way of doing
4109 // this is to test CAP_SYS_NICE capability, but that will require libcap.so
4110 if (geteuid() != 0) {
4111 if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) {
4112 warning("-XX:ThreadPriorityPolicy requires root privilege on Linux");
4113 }
4114 ThreadPriorityPolicy = 0;
4115 }
4116 }
4117 if (UseCriticalJavaThreadPriority) {
4118 os::java_to_os_priority[MaxPriority] = os::java_to_os_priority[CriticalPriority];
4119 }
4120 return 0;
4121 }
4123 OSReturn os::set_native_priority(Thread* thread, int newpri) {
4124 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) return OS_OK;
4126 int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri);
4127 return (ret == 0) ? OS_OK : OS_ERR;
4128 }
4130 OSReturn os::get_native_priority(const Thread* const thread, int *priority_ptr) {
4131 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) {
4132 *priority_ptr = java_to_os_priority[NormPriority];
4133 return OS_OK;
4134 }
4136 errno = 0;
4137 *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id());
4138 return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR);
4139 }
4141 // Hint to the underlying OS that a task switch would not be good.
4142 // Void return because it's a hint and can fail.
4143 void os::hint_no_preempt() {}
4145 ////////////////////////////////////////////////////////////////////////////////
4146 // suspend/resume support
4148 // the low-level signal-based suspend/resume support is a remnant from the
4149 // old VM-suspension that used to be for java-suspension, safepoints etc,
4150 // within hotspot. Now there is a single use-case for this:
4151 // - calling get_thread_pc() on the VMThread by the flat-profiler task
4152 // that runs in the watcher thread.
4153 // The remaining code is greatly simplified from the more general suspension
4154 // code that used to be used.
4155 //
4156 // The protocol is quite simple:
4157 // - suspend:
4158 // - sends a signal to the target thread
4159 // - polls the suspend state of the osthread using a yield loop
4160 // - target thread signal handler (SR_handler) sets suspend state
4161 // and blocks in sigsuspend until continued
4162 // - resume:
4163 // - sets target osthread state to continue
4164 // - sends signal to end the sigsuspend loop in the SR_handler
4165 //
4166 // Note that the SR_lock plays no role in this suspend/resume protocol.
4167 //
4169 static void resume_clear_context(OSThread *osthread) {
4170 osthread->set_ucontext(NULL);
4171 osthread->set_siginfo(NULL);
4172 }
4174 static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo, ucontext_t* context) {
4175 osthread->set_ucontext(context);
4176 osthread->set_siginfo(siginfo);
4177 }
4179 //
4180 // Handler function invoked when a thread's execution is suspended or
4181 // resumed. We have to be careful that only async-safe functions are
4182 // called here (Note: most pthread functions are not async safe and
4183 // should be avoided.)
4184 //
4185 // Note: sigwait() is a more natural fit than sigsuspend() from an
4186 // interface point of view, but sigwait() prevents the signal hander
4187 // from being run. libpthread would get very confused by not having
4188 // its signal handlers run and prevents sigwait()'s use with the
4189 // mutex granting granting signal.
4190 //
4191 // Currently only ever called on the VMThread and JavaThreads (PC sampling)
4192 //
4193 static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) {
4194 // Save and restore errno to avoid confusing native code with EINTR
4195 // after sigsuspend.
4196 int old_errno = errno;
4198 Thread* thread = Thread::current();
4199 OSThread* osthread = thread->osthread();
4200 assert(thread->is_VM_thread() || thread->is_Java_thread(), "Must be VMThread or JavaThread");
4202 os::SuspendResume::State current = osthread->sr.state();
4203 if (current == os::SuspendResume::SR_SUSPEND_REQUEST) {
4204 suspend_save_context(osthread, siginfo, context);
4206 // attempt to switch the state, we assume we had a SUSPEND_REQUEST
4207 os::SuspendResume::State state = osthread->sr.suspended();
4208 if (state == os::SuspendResume::SR_SUSPENDED) {
4209 sigset_t suspend_set; // signals for sigsuspend()
4211 // get current set of blocked signals and unblock resume signal
4212 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set);
4213 sigdelset(&suspend_set, SR_signum);
4215 sr_semaphore.signal();
4216 // wait here until we are resumed
4217 while (1) {
4218 sigsuspend(&suspend_set);
4220 os::SuspendResume::State result = osthread->sr.running();
4221 if (result == os::SuspendResume::SR_RUNNING) {
4222 sr_semaphore.signal();
4223 break;
4224 }
4225 }
4227 } else if (state == os::SuspendResume::SR_RUNNING) {
4228 // request was cancelled, continue
4229 } else {
4230 ShouldNotReachHere();
4231 }
4233 resume_clear_context(osthread);
4234 } else if (current == os::SuspendResume::SR_RUNNING) {
4235 // request was cancelled, continue
4236 } else if (current == os::SuspendResume::SR_WAKEUP_REQUEST) {
4237 // ignore
4238 } else {
4239 // ignore
4240 }
4242 errno = old_errno;
4243 }
4246 static int SR_initialize() {
4247 struct sigaction act;
4248 char *s;
4249 /* Get signal number to use for suspend/resume */
4250 if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) {
4251 int sig = ::strtol(s, 0, 10);
4252 if (sig > 0 || sig < _NSIG) {
4253 SR_signum = sig;
4254 }
4255 }
4257 assert(SR_signum > SIGSEGV && SR_signum > SIGBUS,
4258 "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769");
4260 sigemptyset(&SR_sigset);
4261 sigaddset(&SR_sigset, SR_signum);
4263 /* Set up signal handler for suspend/resume */
4264 act.sa_flags = SA_RESTART|SA_SIGINFO;
4265 act.sa_handler = (void (*)(int)) SR_handler;
4267 // SR_signum is blocked by default.
4268 // 4528190 - We also need to block pthread restart signal (32 on all
4269 // supported Linux platforms). Note that LinuxThreads need to block
4270 // this signal for all threads to work properly. So we don't have
4271 // to use hard-coded signal number when setting up the mask.
4272 pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask);
4274 if (sigaction(SR_signum, &act, 0) == -1) {
4275 return -1;
4276 }
4278 // Save signal flag
4279 os::Linux::set_our_sigflags(SR_signum, act.sa_flags);
4280 return 0;
4281 }
4283 static int sr_notify(OSThread* osthread) {
4284 int status = pthread_kill(osthread->pthread_id(), SR_signum);
4285 assert_status(status == 0, status, "pthread_kill");
4286 return status;
4287 }
4289 // "Randomly" selected value for how long we want to spin
4290 // before bailing out on suspending a thread, also how often
4291 // we send a signal to a thread we want to resume
4292 static const int RANDOMLY_LARGE_INTEGER = 1000000;
4293 static const int RANDOMLY_LARGE_INTEGER2 = 100;
4295 // returns true on success and false on error - really an error is fatal
4296 // but this seems the normal response to library errors
4297 static bool do_suspend(OSThread* osthread) {
4298 assert(osthread->sr.is_running(), "thread should be running");
4299 assert(!sr_semaphore.trywait(), "semaphore has invalid state");
4301 // mark as suspended and send signal
4302 if (osthread->sr.request_suspend() != os::SuspendResume::SR_SUSPEND_REQUEST) {
4303 // failed to switch, state wasn't running?
4304 ShouldNotReachHere();
4305 return false;
4306 }
4308 if (sr_notify(osthread) != 0) {
4309 ShouldNotReachHere();
4310 }
4312 // managed to send the signal and switch to SUSPEND_REQUEST, now wait for SUSPENDED
4313 while (true) {
4314 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) {
4315 break;
4316 } else {
4317 // timeout
4318 os::SuspendResume::State cancelled = osthread->sr.cancel_suspend();
4319 if (cancelled == os::SuspendResume::SR_RUNNING) {
4320 return false;
4321 } else if (cancelled == os::SuspendResume::SR_SUSPENDED) {
4322 // make sure that we consume the signal on the semaphore as well
4323 sr_semaphore.wait();
4324 break;
4325 } else {
4326 ShouldNotReachHere();
4327 return false;
4328 }
4329 }
4330 }
4332 guarantee(osthread->sr.is_suspended(), "Must be suspended");
4333 return true;
4334 }
4336 static void do_resume(OSThread* osthread) {
4337 assert(osthread->sr.is_suspended(), "thread should be suspended");
4338 assert(!sr_semaphore.trywait(), "invalid semaphore state");
4340 if (osthread->sr.request_wakeup() != os::SuspendResume::SR_WAKEUP_REQUEST) {
4341 // failed to switch to WAKEUP_REQUEST
4342 ShouldNotReachHere();
4343 return;
4344 }
4346 while (true) {
4347 if (sr_notify(osthread) == 0) {
4348 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) {
4349 if (osthread->sr.is_running()) {
4350 return;
4351 }
4352 }
4353 } else {
4354 ShouldNotReachHere();
4355 }
4356 }
4358 guarantee(osthread->sr.is_running(), "Must be running!");
4359 }
4361 ////////////////////////////////////////////////////////////////////////////////
4362 // interrupt support
4364 void os::interrupt(Thread* thread) {
4365 assert(Thread::current() == thread || Threads_lock->owned_by_self(),
4366 "possibility of dangling Thread pointer");
4368 OSThread* osthread = thread->osthread();
4370 if (!osthread->interrupted()) {
4371 osthread->set_interrupted(true);
4372 // More than one thread can get here with the same value of osthread,
4373 // resulting in multiple notifications. We do, however, want the store
4374 // to interrupted() to be visible to other threads before we execute unpark().
4375 OrderAccess::fence();
4376 ParkEvent * const slp = thread->_SleepEvent ;
4377 if (slp != NULL) slp->unpark() ;
4378 }
4380 // For JSR166. Unpark even if interrupt status already was set
4381 if (thread->is_Java_thread())
4382 ((JavaThread*)thread)->parker()->unpark();
4384 ParkEvent * ev = thread->_ParkEvent ;
4385 if (ev != NULL) ev->unpark() ;
4387 }
4389 bool os::is_interrupted(Thread* thread, bool clear_interrupted) {
4390 assert(Thread::current() == thread || Threads_lock->owned_by_self(),
4391 "possibility of dangling Thread pointer");
4393 OSThread* osthread = thread->osthread();
4395 bool interrupted = osthread->interrupted();
4397 if (interrupted && clear_interrupted) {
4398 osthread->set_interrupted(false);
4399 // consider thread->_SleepEvent->reset() ... optional optimization
4400 }
4402 return interrupted;
4403 }
4405 ///////////////////////////////////////////////////////////////////////////////////
4406 // signal handling (except suspend/resume)
4408 // This routine may be used by user applications as a "hook" to catch signals.
4409 // The user-defined signal handler must pass unrecognized signals to this
4410 // routine, and if it returns true (non-zero), then the signal handler must
4411 // return immediately. If the flag "abort_if_unrecognized" is true, then this
4412 // routine will never retun false (zero), but instead will execute a VM panic
4413 // routine kill the process.
4414 //
4415 // If this routine returns false, it is OK to call it again. This allows
4416 // the user-defined signal handler to perform checks either before or after
4417 // the VM performs its own checks. Naturally, the user code would be making
4418 // a serious error if it tried to handle an exception (such as a null check
4419 // or breakpoint) that the VM was generating for its own correct operation.
4420 //
4421 // This routine may recognize any of the following kinds of signals:
4422 // SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1.
4423 // It should be consulted by handlers for any of those signals.
4424 //
4425 // The caller of this routine must pass in the three arguments supplied
4426 // to the function referred to in the "sa_sigaction" (not the "sa_handler")
4427 // field of the structure passed to sigaction(). This routine assumes that
4428 // the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART.
4429 //
4430 // Note that the VM will print warnings if it detects conflicting signal
4431 // handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers".
4432 //
4433 extern "C" JNIEXPORT int
4434 JVM_handle_linux_signal(int signo, siginfo_t* siginfo,
4435 void* ucontext, int abort_if_unrecognized);
4437 void signalHandler(int sig, siginfo_t* info, void* uc) {
4438 assert(info != NULL && uc != NULL, "it must be old kernel");
4439 int orig_errno = errno; // Preserve errno value over signal handler.
4440 JVM_handle_linux_signal(sig, info, uc, true);
4441 errno = orig_errno;
4442 }
4445 // This boolean allows users to forward their own non-matching signals
4446 // to JVM_handle_linux_signal, harmlessly.
4447 bool os::Linux::signal_handlers_are_installed = false;
4449 // For signal-chaining
4450 struct sigaction os::Linux::sigact[MAXSIGNUM];
4451 unsigned int os::Linux::sigs = 0;
4452 bool os::Linux::libjsig_is_loaded = false;
4453 typedef struct sigaction *(*get_signal_t)(int);
4454 get_signal_t os::Linux::get_signal_action = NULL;
4456 struct sigaction* os::Linux::get_chained_signal_action(int sig) {
4457 struct sigaction *actp = NULL;
4459 if (libjsig_is_loaded) {
4460 // Retrieve the old signal handler from libjsig
4461 actp = (*get_signal_action)(sig);
4462 }
4463 if (actp == NULL) {
4464 // Retrieve the preinstalled signal handler from jvm
4465 actp = get_preinstalled_handler(sig);
4466 }
4468 return actp;
4469 }
4471 static bool call_chained_handler(struct sigaction *actp, int sig,
4472 siginfo_t *siginfo, void *context) {
4473 // Call the old signal handler
4474 if (actp->sa_handler == SIG_DFL) {
4475 // It's more reasonable to let jvm treat it as an unexpected exception
4476 // instead of taking the default action.
4477 return false;
4478 } else if (actp->sa_handler != SIG_IGN) {
4479 if ((actp->sa_flags & SA_NODEFER) == 0) {
4480 // automaticlly block the signal
4481 sigaddset(&(actp->sa_mask), sig);
4482 }
4484 sa_handler_t hand = NULL;
4485 sa_sigaction_t sa = NULL;
4486 bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0;
4487 // retrieve the chained handler
4488 if (siginfo_flag_set) {
4489 sa = actp->sa_sigaction;
4490 } else {
4491 hand = actp->sa_handler;
4492 }
4494 if ((actp->sa_flags & SA_RESETHAND) != 0) {
4495 actp->sa_handler = SIG_DFL;
4496 }
4498 // try to honor the signal mask
4499 sigset_t oset;
4500 pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset);
4502 // call into the chained handler
4503 if (siginfo_flag_set) {
4504 (*sa)(sig, siginfo, context);
4505 } else {
4506 (*hand)(sig);
4507 }
4509 // restore the signal mask
4510 pthread_sigmask(SIG_SETMASK, &oset, 0);
4511 }
4512 // Tell jvm's signal handler the signal is taken care of.
4513 return true;
4514 }
4516 bool os::Linux::chained_handler(int sig, siginfo_t* siginfo, void* context) {
4517 bool chained = false;
4518 // signal-chaining
4519 if (UseSignalChaining) {
4520 struct sigaction *actp = get_chained_signal_action(sig);
4521 if (actp != NULL) {
4522 chained = call_chained_handler(actp, sig, siginfo, context);
4523 }
4524 }
4525 return chained;
4526 }
4528 struct sigaction* os::Linux::get_preinstalled_handler(int sig) {
4529 if ((( (unsigned int)1 << sig ) & sigs) != 0) {
4530 return &sigact[sig];
4531 }
4532 return NULL;
4533 }
4535 void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) {
4536 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4537 sigact[sig] = oldAct;
4538 sigs |= (unsigned int)1 << sig;
4539 }
4541 // for diagnostic
4542 int os::Linux::sigflags[MAXSIGNUM];
4544 int os::Linux::get_our_sigflags(int sig) {
4545 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4546 return sigflags[sig];
4547 }
4549 void os::Linux::set_our_sigflags(int sig, int flags) {
4550 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4551 sigflags[sig] = flags;
4552 }
4554 void os::Linux::set_signal_handler(int sig, bool set_installed) {
4555 // Check for overwrite.
4556 struct sigaction oldAct;
4557 sigaction(sig, (struct sigaction*)NULL, &oldAct);
4559 void* oldhand = oldAct.sa_sigaction
4560 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction)
4561 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler);
4562 if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) &&
4563 oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) &&
4564 oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) {
4565 if (AllowUserSignalHandlers || !set_installed) {
4566 // Do not overwrite; user takes responsibility to forward to us.
4567 return;
4568 } else if (UseSignalChaining) {
4569 // save the old handler in jvm
4570 save_preinstalled_handler(sig, oldAct);
4571 // libjsig also interposes the sigaction() call below and saves the
4572 // old sigaction on it own.
4573 } else {
4574 fatal(err_msg("Encountered unexpected pre-existing sigaction handler "
4575 "%#lx for signal %d.", (long)oldhand, sig));
4576 }
4577 }
4579 struct sigaction sigAct;
4580 sigfillset(&(sigAct.sa_mask));
4581 sigAct.sa_handler = SIG_DFL;
4582 if (!set_installed) {
4583 sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
4584 } else {
4585 sigAct.sa_sigaction = signalHandler;
4586 sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
4587 }
4588 // Save flags, which are set by ours
4589 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4590 sigflags[sig] = sigAct.sa_flags;
4592 int ret = sigaction(sig, &sigAct, &oldAct);
4593 assert(ret == 0, "check");
4595 void* oldhand2 = oldAct.sa_sigaction
4596 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction)
4597 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler);
4598 assert(oldhand2 == oldhand, "no concurrent signal handler installation");
4599 }
4601 // install signal handlers for signals that HotSpot needs to
4602 // handle in order to support Java-level exception handling.
4604 void os::Linux::install_signal_handlers() {
4605 if (!signal_handlers_are_installed) {
4606 signal_handlers_are_installed = true;
4608 // signal-chaining
4609 typedef void (*signal_setting_t)();
4610 signal_setting_t begin_signal_setting = NULL;
4611 signal_setting_t end_signal_setting = NULL;
4612 begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
4613 dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting"));
4614 if (begin_signal_setting != NULL) {
4615 end_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
4616 dlsym(RTLD_DEFAULT, "JVM_end_signal_setting"));
4617 get_signal_action = CAST_TO_FN_PTR(get_signal_t,
4618 dlsym(RTLD_DEFAULT, "JVM_get_signal_action"));
4619 libjsig_is_loaded = true;
4620 assert(UseSignalChaining, "should enable signal-chaining");
4621 }
4622 if (libjsig_is_loaded) {
4623 // Tell libjsig jvm is setting signal handlers
4624 (*begin_signal_setting)();
4625 }
4627 set_signal_handler(SIGSEGV, true);
4628 set_signal_handler(SIGPIPE, true);
4629 set_signal_handler(SIGBUS, true);
4630 set_signal_handler(SIGILL, true);
4631 set_signal_handler(SIGFPE, true);
4632 #if defined(PPC64)
4633 set_signal_handler(SIGTRAP, true);
4634 #endif
4635 set_signal_handler(SIGXFSZ, true);
4637 if (libjsig_is_loaded) {
4638 // Tell libjsig jvm finishes setting signal handlers
4639 (*end_signal_setting)();
4640 }
4642 // We don't activate signal checker if libjsig is in place, we trust ourselves
4643 // and if UserSignalHandler is installed all bets are off.
4644 // Log that signal checking is off only if -verbose:jni is specified.
4645 if (CheckJNICalls) {
4646 if (libjsig_is_loaded) {
4647 if (PrintJNIResolving) {
4648 tty->print_cr("Info: libjsig is activated, all active signal checking is disabled");
4649 }
4650 check_signals = false;
4651 }
4652 if (AllowUserSignalHandlers) {
4653 if (PrintJNIResolving) {
4654 tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled");
4655 }
4656 check_signals = false;
4657 }
4658 }
4659 }
4660 }
4662 // This is the fastest way to get thread cpu time on Linux.
4663 // Returns cpu time (user+sys) for any thread, not only for current.
4664 // POSIX compliant clocks are implemented in the kernels 2.6.16+.
4665 // It might work on 2.6.10+ with a special kernel/glibc patch.
4666 // For reference, please, see IEEE Std 1003.1-2004:
4667 // http://www.unix.org/single_unix_specification
4669 jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) {
4670 struct timespec tp;
4671 int rc = os::Linux::clock_gettime(clockid, &tp);
4672 assert(rc == 0, "clock_gettime is expected to return 0 code");
4674 return (tp.tv_sec * NANOSECS_PER_SEC) + tp.tv_nsec;
4675 }
4677 /////
4678 // glibc on Linux platform uses non-documented flag
4679 // to indicate, that some special sort of signal
4680 // trampoline is used.
4681 // We will never set this flag, and we should
4682 // ignore this flag in our diagnostic
4683 #ifdef SIGNIFICANT_SIGNAL_MASK
4684 #undef SIGNIFICANT_SIGNAL_MASK
4685 #endif
4686 #define SIGNIFICANT_SIGNAL_MASK (~0x04000000)
4688 static const char* get_signal_handler_name(address handler,
4689 char* buf, int buflen) {
4690 int offset = 0;
4691 bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset);
4692 if (found) {
4693 // skip directory names
4694 const char *p1, *p2;
4695 p1 = buf;
4696 size_t len = strlen(os::file_separator());
4697 while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len;
4698 jio_snprintf(buf, buflen, "%s+0x%x", p1, offset);
4699 } else {
4700 jio_snprintf(buf, buflen, PTR_FORMAT, handler);
4701 }
4702 return buf;
4703 }
4705 static void print_signal_handler(outputStream* st, int sig,
4706 char* buf, size_t buflen) {
4707 struct sigaction sa;
4709 sigaction(sig, NULL, &sa);
4711 // See comment for SIGNIFICANT_SIGNAL_MASK define
4712 sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
4714 st->print("%s: ", os::exception_name(sig, buf, buflen));
4716 address handler = (sa.sa_flags & SA_SIGINFO)
4717 ? CAST_FROM_FN_PTR(address, sa.sa_sigaction)
4718 : CAST_FROM_FN_PTR(address, sa.sa_handler);
4720 if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) {
4721 st->print("SIG_DFL");
4722 } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) {
4723 st->print("SIG_IGN");
4724 } else {
4725 st->print("[%s]", get_signal_handler_name(handler, buf, buflen));
4726 }
4728 st->print(", sa_mask[0]=");
4729 os::Posix::print_signal_set_short(st, &sa.sa_mask);
4731 address rh = VMError::get_resetted_sighandler(sig);
4732 // May be, handler was resetted by VMError?
4733 if(rh != NULL) {
4734 handler = rh;
4735 sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK;
4736 }
4738 st->print(", sa_flags=");
4739 os::Posix::print_sa_flags(st, sa.sa_flags);
4741 // Check: is it our handler?
4742 if(handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) ||
4743 handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) {
4744 // It is our signal handler
4745 // check for flags, reset system-used one!
4746 if((int)sa.sa_flags != os::Linux::get_our_sigflags(sig)) {
4747 st->print(
4748 ", flags was changed from " PTR32_FORMAT ", consider using jsig library",
4749 os::Linux::get_our_sigflags(sig));
4750 }
4751 }
4752 st->cr();
4753 }
4756 #define DO_SIGNAL_CHECK(sig) \
4757 if (!sigismember(&check_signal_done, sig)) \
4758 os::Linux::check_signal_handler(sig)
4760 // This method is a periodic task to check for misbehaving JNI applications
4761 // under CheckJNI, we can add any periodic checks here
4763 void os::run_periodic_checks() {
4765 if (check_signals == false) return;
4767 // SEGV and BUS if overridden could potentially prevent
4768 // generation of hs*.log in the event of a crash, debugging
4769 // such a case can be very challenging, so we absolutely
4770 // check the following for a good measure:
4771 DO_SIGNAL_CHECK(SIGSEGV);
4772 DO_SIGNAL_CHECK(SIGILL);
4773 DO_SIGNAL_CHECK(SIGFPE);
4774 DO_SIGNAL_CHECK(SIGBUS);
4775 DO_SIGNAL_CHECK(SIGPIPE);
4776 DO_SIGNAL_CHECK(SIGXFSZ);
4777 #if defined(PPC64)
4778 DO_SIGNAL_CHECK(SIGTRAP);
4779 #endif
4781 // ReduceSignalUsage allows the user to override these handlers
4782 // see comments at the very top and jvm_solaris.h
4783 if (!ReduceSignalUsage) {
4784 DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL);
4785 DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL);
4786 DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL);
4787 DO_SIGNAL_CHECK(BREAK_SIGNAL);
4788 }
4790 DO_SIGNAL_CHECK(SR_signum);
4791 DO_SIGNAL_CHECK(INTERRUPT_SIGNAL);
4792 }
4794 typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *);
4796 static os_sigaction_t os_sigaction = NULL;
4798 void os::Linux::check_signal_handler(int sig) {
4799 char buf[O_BUFLEN];
4800 address jvmHandler = NULL;
4803 struct sigaction act;
4804 if (os_sigaction == NULL) {
4805 // only trust the default sigaction, in case it has been interposed
4806 os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction");
4807 if (os_sigaction == NULL) return;
4808 }
4810 os_sigaction(sig, (struct sigaction*)NULL, &act);
4813 act.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
4815 address thisHandler = (act.sa_flags & SA_SIGINFO)
4816 ? CAST_FROM_FN_PTR(address, act.sa_sigaction)
4817 : CAST_FROM_FN_PTR(address, act.sa_handler) ;
4820 switch(sig) {
4821 case SIGSEGV:
4822 case SIGBUS:
4823 case SIGFPE:
4824 case SIGPIPE:
4825 case SIGILL:
4826 case SIGXFSZ:
4827 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler);
4828 break;
4830 case SHUTDOWN1_SIGNAL:
4831 case SHUTDOWN2_SIGNAL:
4832 case SHUTDOWN3_SIGNAL:
4833 case BREAK_SIGNAL:
4834 jvmHandler = (address)user_handler();
4835 break;
4837 case INTERRUPT_SIGNAL:
4838 jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL);
4839 break;
4841 default:
4842 if (sig == SR_signum) {
4843 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler);
4844 } else {
4845 return;
4846 }
4847 break;
4848 }
4850 if (thisHandler != jvmHandler) {
4851 tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN));
4852 tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN));
4853 tty->print_cr(" found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN));
4854 // No need to check this sig any longer
4855 sigaddset(&check_signal_done, sig);
4856 // Running under non-interactive shell, SHUTDOWN2_SIGNAL will be reassigned SIG_IGN
4857 if (sig == SHUTDOWN2_SIGNAL && !isatty(fileno(stdin))) {
4858 tty->print_cr("Running in non-interactive shell, %s handler is replaced by shell",
4859 exception_name(sig, buf, O_BUFLEN));
4860 }
4861 } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) {
4862 tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN));
4863 tty->print("expected:" PTR32_FORMAT, os::Linux::get_our_sigflags(sig));
4864 tty->print_cr(" found:" PTR32_FORMAT, act.sa_flags);
4865 // No need to check this sig any longer
4866 sigaddset(&check_signal_done, sig);
4867 }
4869 // Dump all the signal
4870 if (sigismember(&check_signal_done, sig)) {
4871 print_signal_handlers(tty, buf, O_BUFLEN);
4872 }
4873 }
4875 extern void report_error(char* file_name, int line_no, char* title, char* format, ...);
4877 extern bool signal_name(int signo, char* buf, size_t len);
4879 const char* os::exception_name(int exception_code, char* buf, size_t size) {
4880 if (0 < exception_code && exception_code <= SIGRTMAX) {
4881 // signal
4882 if (!signal_name(exception_code, buf, size)) {
4883 jio_snprintf(buf, size, "SIG%d", exception_code);
4884 }
4885 return buf;
4886 } else {
4887 return NULL;
4888 }
4889 }
4891 // this is called _before_ the most of global arguments have been parsed
4892 void os::init(void) {
4893 char dummy; /* used to get a guess on initial stack address */
4894 // first_hrtime = gethrtime();
4896 // With LinuxThreads the JavaMain thread pid (primordial thread)
4897 // is different than the pid of the java launcher thread.
4898 // So, on Linux, the launcher thread pid is passed to the VM
4899 // via the sun.java.launcher.pid property.
4900 // Use this property instead of getpid() if it was correctly passed.
4901 // See bug 6351349.
4902 pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid();
4904 _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid();
4906 clock_tics_per_sec = sysconf(_SC_CLK_TCK);
4908 init_random(1234567);
4910 ThreadCritical::initialize();
4912 Linux::set_page_size(sysconf(_SC_PAGESIZE));
4913 if (Linux::page_size() == -1) {
4914 fatal(err_msg("os_linux.cpp: os::init: sysconf failed (%s)",
4915 strerror(errno)));
4916 }
4917 init_page_sizes((size_t) Linux::page_size());
4919 Linux::initialize_system_info();
4921 // main_thread points to the aboriginal thread
4922 Linux::_main_thread = pthread_self();
4924 Linux::clock_init();
4925 initial_time_count = javaTimeNanos();
4927 // pthread_condattr initialization for monotonic clock
4928 int status;
4929 pthread_condattr_t* _condattr = os::Linux::condAttr();
4930 if ((status = pthread_condattr_init(_condattr)) != 0) {
4931 fatal(err_msg("pthread_condattr_init: %s", strerror(status)));
4932 }
4933 // Only set the clock if CLOCK_MONOTONIC is available
4934 if (Linux::supports_monotonic_clock()) {
4935 if ((status = pthread_condattr_setclock(_condattr, CLOCK_MONOTONIC)) != 0) {
4936 if (status == EINVAL) {
4937 warning("Unable to use monotonic clock with relative timed-waits" \
4938 " - changes to the time-of-day clock may have adverse affects");
4939 } else {
4940 fatal(err_msg("pthread_condattr_setclock: %s", strerror(status)));
4941 }
4942 }
4943 }
4944 // else it defaults to CLOCK_REALTIME
4946 pthread_mutex_init(&dl_mutex, NULL);
4948 // If the pagesize of the VM is greater than 8K determine the appropriate
4949 // number of initial guard pages. The user can change this with the
4950 // command line arguments, if needed.
4951 if (vm_page_size() > (int)Linux::vm_default_page_size()) {
4952 StackYellowPages = 1;
4953 StackRedPages = 1;
4954 StackShadowPages = round_to((StackShadowPages*Linux::vm_default_page_size()), vm_page_size()) / vm_page_size();
4955 }
4956 }
4958 // To install functions for atexit system call
4959 extern "C" {
4960 static void perfMemory_exit_helper() {
4961 perfMemory_exit();
4962 }
4963 }
4965 // this is called _after_ the global arguments have been parsed
4966 jint os::init_2(void)
4967 {
4968 Linux::fast_thread_clock_init();
4970 // Allocate a single page and mark it as readable for safepoint polling
4971 #ifdef OPT_SAFEPOINT
4972 void * p = (void *)(0x10000);
4973 address polling_page = (address) ::mmap(p, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
4974 #else
4975 address polling_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
4976 #endif
4977 guarantee( polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page" );
4979 os::set_polling_page( polling_page );
4981 #ifndef PRODUCT
4982 if(Verbose && PrintMiscellaneous)
4983 tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n", (intptr_t)polling_page);
4984 #endif
4986 if (!UseMembar) {
4987 address mem_serialize_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
4988 guarantee( mem_serialize_page != MAP_FAILED, "mmap Failed for memory serialize page");
4989 os::set_memory_serialize_page( mem_serialize_page );
4991 #ifndef PRODUCT
4992 if(Verbose && PrintMiscellaneous)
4993 tty->print("[Memory Serialize Page address: " INTPTR_FORMAT "]\n", (intptr_t)mem_serialize_page);
4994 #endif
4995 }
4997 // initialize suspend/resume support - must do this before signal_sets_init()
4998 if (SR_initialize() != 0) {
4999 perror("SR_initialize failed");
5000 return JNI_ERR;
5001 }
5003 Linux::signal_sets_init();
5004 Linux::install_signal_handlers();
5006 // Check minimum allowable stack size for thread creation and to initialize
5007 // the java system classes, including StackOverflowError - depends on page
5008 // size. Add a page for compiler2 recursion in main thread.
5009 // Add in 2*BytesPerWord times page size to account for VM stack during
5010 // class initialization depending on 32 or 64 bit VM.
5012 /* 2014/1/2 Liao: JDK8 requires larger -Xss option.
5013 * TongWeb cannot run with -Xss192K.
5014 * We are not sure whether this causes errors, so simply print a warning. */
5015 size_t min_stack_allowed_jdk6 = os::Linux::min_stack_allowed;
5016 os::Linux::min_stack_allowed = MAX2(os::Linux::min_stack_allowed,
5017 (size_t)(StackYellowPages+StackRedPages+StackShadowPages) * Linux::page_size() +
5018 (2*BytesPerWord COMPILER2_PRESENT(+1)) * Linux::vm_default_page_size());
5020 size_t threadStackSizeInBytes = ThreadStackSize * K;
5021 if (threadStackSizeInBytes != 0 &&
5022 threadStackSizeInBytes < min_stack_allowed_jdk6) {
5023 tty->print_cr("\nThe stack size specified is too small, "
5024 "Specify at least %dk",
5025 os::Linux::min_stack_allowed/ K);
5026 return JNI_ERR;
5027 }
5029 // Make the stack size a multiple of the page size so that
5030 // the yellow/red zones can be guarded.
5031 JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes,
5032 vm_page_size()));
5034 Linux::capture_initial_stack(JavaThread::stack_size_at_create());
5036 #if defined(IA32)
5037 workaround_expand_exec_shield_cs_limit();
5038 #endif
5040 Linux::libpthread_init();
5041 if (PrintMiscellaneous && (Verbose || WizardMode)) {
5042 tty->print_cr("[HotSpot is running with %s, %s(%s)]\n",
5043 Linux::glibc_version(), Linux::libpthread_version(),
5044 Linux::is_floating_stack() ? "floating stack" : "fixed stack");
5045 }
5047 if (UseNUMA) {
5048 if (!Linux::libnuma_init()) {
5049 UseNUMA = false;
5050 } else {
5051 if ((Linux::numa_max_node() < 1)) {
5052 // There's only one node(they start from 0), disable NUMA.
5053 UseNUMA = false;
5054 }
5055 }
5056 // With SHM and HugeTLBFS large pages we cannot uncommit a page, so there's no way
5057 // we can make the adaptive lgrp chunk resizing work. If the user specified
5058 // both UseNUMA and UseLargePages (or UseSHM/UseHugeTLBFS) on the command line - warn and
5059 // disable adaptive resizing.
5060 if (UseNUMA && UseLargePages && !can_commit_large_page_memory()) {
5061 if (FLAG_IS_DEFAULT(UseNUMA)) {
5062 UseNUMA = false;
5063 } else {
5064 if (FLAG_IS_DEFAULT(UseLargePages) &&
5065 FLAG_IS_DEFAULT(UseSHM) &&
5066 FLAG_IS_DEFAULT(UseHugeTLBFS)) {
5067 UseLargePages = false;
5068 } else {
5069 warning("UseNUMA is not fully compatible with SHM/HugeTLBFS large pages, disabling adaptive resizing");
5070 UseAdaptiveSizePolicy = false;
5071 UseAdaptiveNUMAChunkSizing = false;
5072 }
5073 }
5074 }
5075 if (!UseNUMA && ForceNUMA) {
5076 UseNUMA = true;
5077 }
5078 }
5080 if (MaxFDLimit) {
5081 // set the number of file descriptors to max. print out error
5082 // if getrlimit/setrlimit fails but continue regardless.
5083 struct rlimit nbr_files;
5084 int status = getrlimit(RLIMIT_NOFILE, &nbr_files);
5085 if (status != 0) {
5086 if (PrintMiscellaneous && (Verbose || WizardMode))
5087 perror("os::init_2 getrlimit failed");
5088 } else {
5089 nbr_files.rlim_cur = nbr_files.rlim_max;
5090 status = setrlimit(RLIMIT_NOFILE, &nbr_files);
5091 if (status != 0) {
5092 if (PrintMiscellaneous && (Verbose || WizardMode))
5093 perror("os::init_2 setrlimit failed");
5094 }
5095 }
5096 }
5098 // Initialize lock used to serialize thread creation (see os::create_thread)
5099 Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false));
5101 // at-exit methods are called in the reverse order of their registration.
5102 // atexit functions are called on return from main or as a result of a
5103 // call to exit(3C). There can be only 32 of these functions registered
5104 // and atexit() does not set errno.
5106 if (PerfAllowAtExitRegistration) {
5107 // only register atexit functions if PerfAllowAtExitRegistration is set.
5108 // atexit functions can be delayed until process exit time, which
5109 // can be problematic for embedded VM situations. Embedded VMs should
5110 // call DestroyJavaVM() to assure that VM resources are released.
5112 // note: perfMemory_exit_helper atexit function may be removed in
5113 // the future if the appropriate cleanup code can be added to the
5114 // VM_Exit VMOperation's doit method.
5115 if (atexit(perfMemory_exit_helper) != 0) {
5116 warning("os::init_2 atexit(perfMemory_exit_helper) failed");
5117 }
5118 }
5120 // initialize thread priority policy
5121 prio_init();
5123 return JNI_OK;
5124 }
5126 // Mark the polling page as unreadable
5127 void os::make_polling_page_unreadable(void) {
5128 if( !guard_memory((char*)_polling_page, Linux::page_size()) )
5129 fatal("Could not disable polling page");
5130 };
5132 // Mark the polling page as readable
5133 void os::make_polling_page_readable(void) {
5134 if( !linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) {
5135 fatal("Could not enable polling page");
5136 }
5137 };
5139 static int os_cpu_count(const cpu_set_t* cpus) {
5140 int count = 0;
5141 // only look up to the number of configured processors
5142 for (int i = 0; i < os::processor_count(); i++) {
5143 if (CPU_ISSET(i, cpus)) {
5144 count++;
5145 }
5146 }
5147 return count;
5148 }
5150 // Get the current number of available processors for this process.
5151 // This value can change at any time during a process's lifetime.
5152 // sched_getaffinity gives an accurate answer as it accounts for cpusets.
5153 // If anything goes wrong we fallback to returning the number of online
5154 // processors - which can be greater than the number available to the process.
5155 int os::active_processor_count() {
5156 cpu_set_t cpus; // can represent at most 1024 (CPU_SETSIZE) processors
5157 int cpus_size = sizeof(cpu_set_t);
5158 int cpu_count = 0;
5160 // pid 0 means the current thread - which we have to assume represents the process
5161 if (sched_getaffinity(0, cpus_size, &cpus) == 0) {
5162 cpu_count = os_cpu_count(&cpus);
5163 if (PrintActiveCpus) {
5164 tty->print_cr("active_processor_count: sched_getaffinity processor count: %d", cpu_count);
5165 }
5166 }
5167 else {
5168 cpu_count = ::sysconf(_SC_NPROCESSORS_ONLN);
5169 warning("sched_getaffinity failed (%s)- using online processor count (%d) "
5170 "which may exceed available processors", strerror(errno), cpu_count);
5171 }
5173 assert(cpu_count > 0 && cpu_count <= processor_count(), "sanity check");
5174 return cpu_count;
5175 }
5177 void os::set_native_thread_name(const char *name) {
5178 // Not yet implemented.
5179 return;
5180 }
5182 bool os::distribute_processes(uint length, uint* distribution) {
5183 // Not yet implemented.
5184 return false;
5185 }
5187 bool os::bind_to_processor(uint processor_id) {
5188 // Not yet implemented.
5189 return false;
5190 }
5192 ///
5194 void os::SuspendedThreadTask::internal_do_task() {
5195 if (do_suspend(_thread->osthread())) {
5196 SuspendedThreadTaskContext context(_thread, _thread->osthread()->ucontext());
5197 do_task(context);
5198 do_resume(_thread->osthread());
5199 }
5200 }
5202 class PcFetcher : public os::SuspendedThreadTask {
5203 public:
5204 PcFetcher(Thread* thread) : os::SuspendedThreadTask(thread) {}
5205 ExtendedPC result();
5206 protected:
5207 void do_task(const os::SuspendedThreadTaskContext& context);
5208 private:
5209 ExtendedPC _epc;
5210 };
5212 ExtendedPC PcFetcher::result() {
5213 guarantee(is_done(), "task is not done yet.");
5214 return _epc;
5215 }
5217 void PcFetcher::do_task(const os::SuspendedThreadTaskContext& context) {
5218 Thread* thread = context.thread();
5219 OSThread* osthread = thread->osthread();
5220 if (osthread->ucontext() != NULL) {
5221 _epc = os::Linux::ucontext_get_pc((ucontext_t *) context.ucontext());
5222 } else {
5223 // NULL context is unexpected, double-check this is the VMThread
5224 guarantee(thread->is_VM_thread(), "can only be called for VMThread");
5225 }
5226 }
5228 // Suspends the target using the signal mechanism and then grabs the PC before
5229 // resuming the target. Used by the flat-profiler only
5230 ExtendedPC os::get_thread_pc(Thread* thread) {
5231 // Make sure that it is called by the watcher for the VMThread
5232 assert(Thread::current()->is_Watcher_thread(), "Must be watcher");
5233 assert(thread->is_VM_thread(), "Can only be called for VMThread");
5235 PcFetcher fetcher(thread);
5236 fetcher.run();
5237 return fetcher.result();
5238 }
5240 int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond, pthread_mutex_t *_mutex, const struct timespec *_abstime)
5241 {
5242 if (is_NPTL()) {
5243 return pthread_cond_timedwait(_cond, _mutex, _abstime);
5244 } else {
5245 // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control
5246 // word back to default 64bit precision if condvar is signaled. Java
5247 // wants 53bit precision. Save and restore current value.
5248 int fpu = get_fpu_control_word();
5249 int status = pthread_cond_timedwait(_cond, _mutex, _abstime);
5250 set_fpu_control_word(fpu);
5251 return status;
5252 }
5253 }
5255 ////////////////////////////////////////////////////////////////////////////////
5256 // debug support
5258 bool os::find(address addr, outputStream* st) {
5259 Dl_info dlinfo;
5260 memset(&dlinfo, 0, sizeof(dlinfo));
5261 if (dladdr(addr, &dlinfo) != 0) {
5262 st->print(PTR_FORMAT ": ", addr);
5263 if (dlinfo.dli_sname != NULL && dlinfo.dli_saddr != NULL) {
5264 st->print("%s+%#x", dlinfo.dli_sname,
5265 addr - (intptr_t)dlinfo.dli_saddr);
5266 } else if (dlinfo.dli_fbase != NULL) {
5267 st->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase);
5268 } else {
5269 st->print("<absolute address>");
5270 }
5271 if (dlinfo.dli_fname != NULL) {
5272 st->print(" in %s", dlinfo.dli_fname);
5273 }
5274 if (dlinfo.dli_fbase != NULL) {
5275 st->print(" at " PTR_FORMAT, dlinfo.dli_fbase);
5276 }
5277 st->cr();
5279 if (Verbose) {
5280 // decode some bytes around the PC
5281 address begin = clamp_address_in_page(addr-40, addr, os::vm_page_size());
5282 address end = clamp_address_in_page(addr+40, addr, os::vm_page_size());
5283 address lowest = (address) dlinfo.dli_sname;
5284 if (!lowest) lowest = (address) dlinfo.dli_fbase;
5285 if (begin < lowest) begin = lowest;
5286 Dl_info dlinfo2;
5287 if (dladdr(end, &dlinfo2) != 0 && dlinfo2.dli_saddr != dlinfo.dli_saddr
5288 && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin)
5289 end = (address) dlinfo2.dli_saddr;
5290 Disassembler::decode(begin, end, st);
5291 }
5292 return true;
5293 }
5294 return false;
5295 }
5297 ////////////////////////////////////////////////////////////////////////////////
5298 // misc
5300 // This does not do anything on Linux. This is basically a hook for being
5301 // able to use structured exception handling (thread-local exception filters)
5302 // on, e.g., Win32.
5303 void
5304 os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method,
5305 JavaCallArguments* args, Thread* thread) {
5306 f(value, method, args, thread);
5307 }
5309 void os::print_statistics() {
5310 }
5312 int os::message_box(const char* title, const char* message) {
5313 int i;
5314 fdStream err(defaultStream::error_fd());
5315 for (i = 0; i < 78; i++) err.print_raw("=");
5316 err.cr();
5317 err.print_raw_cr(title);
5318 for (i = 0; i < 78; i++) err.print_raw("-");
5319 err.cr();
5320 err.print_raw_cr(message);
5321 for (i = 0; i < 78; i++) err.print_raw("=");
5322 err.cr();
5324 char buf[16];
5325 // Prevent process from exiting upon "read error" without consuming all CPU
5326 while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); }
5328 return buf[0] == 'y' || buf[0] == 'Y';
5329 }
5331 int os::stat(const char *path, struct stat *sbuf) {
5332 char pathbuf[MAX_PATH];
5333 if (strlen(path) > MAX_PATH - 1) {
5334 errno = ENAMETOOLONG;
5335 return -1;
5336 }
5337 os::native_path(strcpy(pathbuf, path));
5338 return ::stat(pathbuf, sbuf);
5339 }
5341 bool os::check_heap(bool force) {
5342 return true;
5343 }
5345 int local_vsnprintf(char* buf, size_t count, const char* format, va_list args) {
5346 return ::vsnprintf(buf, count, format, args);
5347 }
5349 // Is a (classpath) directory empty?
5350 bool os::dir_is_empty(const char* path) {
5351 DIR *dir = NULL;
5352 struct dirent *ptr;
5354 dir = opendir(path);
5355 if (dir == NULL) return true;
5357 /* Scan the directory */
5358 bool result = true;
5359 char buf[sizeof(struct dirent) + MAX_PATH];
5360 while (result && (ptr = ::readdir(dir)) != NULL) {
5361 if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) {
5362 result = false;
5363 }
5364 }
5365 closedir(dir);
5366 return result;
5367 }
5369 // This code originates from JDK's sysOpen and open64_w
5370 // from src/solaris/hpi/src/system_md.c
5372 #ifndef O_DELETE
5373 #define O_DELETE 0x10000
5374 #endif
5376 // Open a file. Unlink the file immediately after open returns
5377 // if the specified oflag has the O_DELETE flag set.
5378 // O_DELETE is used only in j2se/src/share/native/java/util/zip/ZipFile.c
5380 int os::open(const char *path, int oflag, int mode) {
5382 if (strlen(path) > MAX_PATH - 1) {
5383 errno = ENAMETOOLONG;
5384 return -1;
5385 }
5386 int fd;
5387 int o_delete = (oflag & O_DELETE);
5388 oflag = oflag & ~O_DELETE;
5390 fd = ::open64(path, oflag, mode);
5391 if (fd == -1) return -1;
5393 //If the open succeeded, the file might still be a directory
5394 {
5395 struct stat64 buf64;
5396 int ret = ::fstat64(fd, &buf64);
5397 int st_mode = buf64.st_mode;
5399 if (ret != -1) {
5400 if ((st_mode & S_IFMT) == S_IFDIR) {
5401 errno = EISDIR;
5402 ::close(fd);
5403 return -1;
5404 }
5405 } else {
5406 ::close(fd);
5407 return -1;
5408 }
5409 }
5411 /*
5412 * All file descriptors that are opened in the JVM and not
5413 * specifically destined for a subprocess should have the
5414 * close-on-exec flag set. If we don't set it, then careless 3rd
5415 * party native code might fork and exec without closing all
5416 * appropriate file descriptors (e.g. as we do in closeDescriptors in
5417 * UNIXProcess.c), and this in turn might:
5418 *
5419 * - cause end-of-file to fail to be detected on some file
5420 * descriptors, resulting in mysterious hangs, or
5421 *
5422 * - might cause an fopen in the subprocess to fail on a system
5423 * suffering from bug 1085341.
5424 *
5425 * (Yes, the default setting of the close-on-exec flag is a Unix
5426 * design flaw)
5427 *
5428 * See:
5429 * 1085341: 32-bit stdio routines should support file descriptors >255
5430 * 4843136: (process) pipe file descriptor from Runtime.exec not being closed
5431 * 6339493: (process) Runtime.exec does not close all file descriptors on Solaris 9
5432 */
5433 #ifdef FD_CLOEXEC
5434 {
5435 int flags = ::fcntl(fd, F_GETFD);
5436 if (flags != -1)
5437 ::fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
5438 }
5439 #endif
5441 if (o_delete != 0) {
5442 ::unlink(path);
5443 }
5444 return fd;
5445 }
5448 // create binary file, rewriting existing file if required
5449 int os::create_binary_file(const char* path, bool rewrite_existing) {
5450 int oflags = O_WRONLY | O_CREAT;
5451 if (!rewrite_existing) {
5452 oflags |= O_EXCL;
5453 }
5454 return ::open64(path, oflags, S_IREAD | S_IWRITE);
5455 }
5457 // return current position of file pointer
5458 jlong os::current_file_offset(int fd) {
5459 return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR);
5460 }
5462 // move file pointer to the specified offset
5463 jlong os::seek_to_file_offset(int fd, jlong offset) {
5464 return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET);
5465 }
5467 // This code originates from JDK's sysAvailable
5468 // from src/solaris/hpi/src/native_threads/src/sys_api_td.c
5470 int os::available(int fd, jlong *bytes) {
5471 jlong cur, end;
5472 int mode;
5473 struct stat64 buf64;
5475 if (::fstat64(fd, &buf64) >= 0) {
5476 mode = buf64.st_mode;
5477 if (S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) {
5478 /*
5479 * XXX: is the following call interruptible? If so, this might
5480 * need to go through the INTERRUPT_IO() wrapper as for other
5481 * blocking, interruptible calls in this file.
5482 */
5483 int n;
5484 if (::ioctl(fd, FIONREAD, &n) >= 0) {
5485 *bytes = n;
5486 return 1;
5487 }
5488 }
5489 }
5490 if ((cur = ::lseek64(fd, 0L, SEEK_CUR)) == -1) {
5491 return 0;
5492 } else if ((end = ::lseek64(fd, 0L, SEEK_END)) == -1) {
5493 return 0;
5494 } else if (::lseek64(fd, cur, SEEK_SET) == -1) {
5495 return 0;
5496 }
5497 *bytes = end - cur;
5498 return 1;
5499 }
5501 int os::socket_available(int fd, jint *pbytes) {
5502 // Linux doc says EINTR not returned, unlike Solaris
5503 int ret = ::ioctl(fd, FIONREAD, pbytes);
5505 //%% note ioctl can return 0 when successful, JVM_SocketAvailable
5506 // is expected to return 0 on failure and 1 on success to the jdk.
5507 return (ret < 0) ? 0 : 1;
5508 }
5510 // Map a block of memory.
5511 char* os::pd_map_memory(int fd, const char* file_name, size_t file_offset,
5512 char *addr, size_t bytes, bool read_only,
5513 bool allow_exec) {
5514 int prot;
5515 int flags = MAP_PRIVATE;
5517 if (read_only) {
5518 prot = PROT_READ;
5519 } else {
5520 prot = PROT_READ | PROT_WRITE;
5521 }
5523 if (allow_exec) {
5524 prot |= PROT_EXEC;
5525 }
5527 if (addr != NULL) {
5528 flags |= MAP_FIXED;
5529 }
5531 char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags,
5532 fd, file_offset);
5533 if (mapped_address == MAP_FAILED) {
5534 return NULL;
5535 }
5536 return mapped_address;
5537 }
5540 // Remap a block of memory.
5541 char* os::pd_remap_memory(int fd, const char* file_name, size_t file_offset,
5542 char *addr, size_t bytes, bool read_only,
5543 bool allow_exec) {
5544 // same as map_memory() on this OS
5545 return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only,
5546 allow_exec);
5547 }
5550 // Unmap a block of memory.
5551 bool os::pd_unmap_memory(char* addr, size_t bytes) {
5552 return munmap(addr, bytes) == 0;
5553 }
5555 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time);
5557 static clockid_t thread_cpu_clockid(Thread* thread) {
5558 pthread_t tid = thread->osthread()->pthread_id();
5559 clockid_t clockid;
5561 // Get thread clockid
5562 int rc = os::Linux::pthread_getcpuclockid(tid, &clockid);
5563 assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code");
5564 return clockid;
5565 }
5567 // current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool)
5568 // are used by JVM M&M and JVMTI to get user+sys or user CPU time
5569 // of a thread.
5570 //
5571 // current_thread_cpu_time() and thread_cpu_time(Thread*) returns
5572 // the fast estimate available on the platform.
5574 jlong os::current_thread_cpu_time() {
5575 if (os::Linux::supports_fast_thread_cpu_time()) {
5576 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
5577 } else {
5578 // return user + sys since the cost is the same
5579 return slow_thread_cpu_time(Thread::current(), true /* user + sys */);
5580 }
5581 }
5583 jlong os::thread_cpu_time(Thread* thread) {
5584 // consistent with what current_thread_cpu_time() returns
5585 if (os::Linux::supports_fast_thread_cpu_time()) {
5586 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread));
5587 } else {
5588 return slow_thread_cpu_time(thread, true /* user + sys */);
5589 }
5590 }
5592 jlong os::current_thread_cpu_time(bool user_sys_cpu_time) {
5593 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
5594 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
5595 } else {
5596 return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time);
5597 }
5598 }
5600 jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
5601 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
5602 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread));
5603 } else {
5604 return slow_thread_cpu_time(thread, user_sys_cpu_time);
5605 }
5606 }
5608 //
5609 // -1 on error.
5610 //
5612 PRAGMA_DIAG_PUSH
5613 PRAGMA_FORMAT_NONLITERAL_IGNORED
5614 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
5615 static bool proc_task_unchecked = true;
5616 static const char *proc_stat_path = "/proc/%d/stat";
5617 pid_t tid = thread->osthread()->thread_id();
5618 char *s;
5619 char stat[2048];
5620 int statlen;
5621 char proc_name[64];
5622 int count;
5623 long sys_time, user_time;
5624 char cdummy;
5625 int idummy;
5626 long ldummy;
5627 FILE *fp;
5629 // The /proc/<tid>/stat aggregates per-process usage on
5630 // new Linux kernels 2.6+ where NPTL is supported.
5631 // The /proc/self/task/<tid>/stat still has the per-thread usage.
5632 // See bug 6328462.
5633 // There possibly can be cases where there is no directory
5634 // /proc/self/task, so we check its availability.
5635 if (proc_task_unchecked && os::Linux::is_NPTL()) {
5636 // This is executed only once
5637 proc_task_unchecked = false;
5638 fp = fopen("/proc/self/task", "r");
5639 if (fp != NULL) {
5640 proc_stat_path = "/proc/self/task/%d/stat";
5641 fclose(fp);
5642 }
5643 }
5645 sprintf(proc_name, proc_stat_path, tid);
5646 fp = fopen(proc_name, "r");
5647 if ( fp == NULL ) return -1;
5648 statlen = fread(stat, 1, 2047, fp);
5649 stat[statlen] = '\0';
5650 fclose(fp);
5652 // Skip pid and the command string. Note that we could be dealing with
5653 // weird command names, e.g. user could decide to rename java launcher
5654 // to "java 1.4.2 :)", then the stat file would look like
5655 // 1234 (java 1.4.2 :)) R ... ...
5656 // We don't really need to know the command string, just find the last
5657 // occurrence of ")" and then start parsing from there. See bug 4726580.
5658 s = strrchr(stat, ')');
5659 if (s == NULL ) return -1;
5661 // Skip blank chars
5662 do s++; while (isspace(*s));
5664 count = sscanf(s,"%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu",
5665 &cdummy, &idummy, &idummy, &idummy, &idummy, &idummy,
5666 &ldummy, &ldummy, &ldummy, &ldummy, &ldummy,
5667 &user_time, &sys_time);
5668 if ( count != 13 ) return -1;
5669 if (user_sys_cpu_time) {
5670 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec);
5671 } else {
5672 return (jlong)user_time * (1000000000 / clock_tics_per_sec);
5673 }
5674 }
5675 PRAGMA_DIAG_POP
5677 void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
5678 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits
5679 info_ptr->may_skip_backward = false; // elapsed time not wall time
5680 info_ptr->may_skip_forward = false; // elapsed time not wall time
5681 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned
5682 }
5684 void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
5685 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits
5686 info_ptr->may_skip_backward = false; // elapsed time not wall time
5687 info_ptr->may_skip_forward = false; // elapsed time not wall time
5688 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned
5689 }
5691 bool os::is_thread_cpu_time_supported() {
5692 return true;
5693 }
5695 // System loadavg support. Returns -1 if load average cannot be obtained.
5696 // Linux doesn't yet have a (official) notion of processor sets,
5697 // so just return the system wide load average.
5698 int os::loadavg(double loadavg[], int nelem) {
5699 return ::getloadavg(loadavg, nelem);
5700 }
5702 void os::pause() {
5703 char filename[MAX_PATH];
5704 if (PauseAtStartupFile && PauseAtStartupFile[0]) {
5705 jio_snprintf(filename, MAX_PATH, PauseAtStartupFile);
5706 } else {
5707 jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id());
5708 }
5710 int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
5711 if (fd != -1) {
5712 struct stat buf;
5713 ::close(fd);
5714 while (::stat(filename, &buf) == 0) {
5715 (void)::poll(NULL, 0, 100);
5716 }
5717 } else {
5718 jio_fprintf(stderr,
5719 "Could not open pause file '%s', continuing immediately.\n", filename);
5720 }
5721 }
5724 // Refer to the comments in os_solaris.cpp park-unpark.
5725 //
5726 // Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can
5727 // hang indefinitely. For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable.
5728 // For specifics regarding the bug see GLIBC BUGID 261237 :
5729 // http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html.
5730 // Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future
5731 // will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar
5732 // is used. (The simple C test-case provided in the GLIBC bug report manifests the
5733 // hang). The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos()
5734 // and monitorenter when we're using 1-0 locking. All those operations may result in
5735 // calls to pthread_cond_timedwait(). Using LD_ASSUME_KERNEL to use an older version
5736 // of libpthread avoids the problem, but isn't practical.
5737 //
5738 // Possible remedies:
5739 //
5740 // 1. Establish a minimum relative wait time. 50 to 100 msecs seems to work.
5741 // This is palliative and probabilistic, however. If the thread is preempted
5742 // between the call to compute_abstime() and pthread_cond_timedwait(), more
5743 // than the minimum period may have passed, and the abstime may be stale (in the
5744 // past) resultin in a hang. Using this technique reduces the odds of a hang
5745 // but the JVM is still vulnerable, particularly on heavily loaded systems.
5746 //
5747 // 2. Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead
5748 // of the usual flag-condvar-mutex idiom. The write side of the pipe is set
5749 // NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo)
5750 // reduces to poll()+read(). This works well, but consumes 2 FDs per extant
5751 // thread.
5752 //
5753 // 3. Embargo pthread_cond_timedwait() and implement a native "chron" thread
5754 // that manages timeouts. We'd emulate pthread_cond_timedwait() by enqueuing
5755 // a timeout request to the chron thread and then blocking via pthread_cond_wait().
5756 // This also works well. In fact it avoids kernel-level scalability impediments
5757 // on certain platforms that don't handle lots of active pthread_cond_timedwait()
5758 // timers in a graceful fashion.
5759 //
5760 // 4. When the abstime value is in the past it appears that control returns
5761 // correctly from pthread_cond_timedwait(), but the condvar is left corrupt.
5762 // Subsequent timedwait/wait calls may hang indefinitely. Given that, we
5763 // can avoid the problem by reinitializing the condvar -- by cond_destroy()
5764 // followed by cond_init() -- after all calls to pthread_cond_timedwait().
5765 // It may be possible to avoid reinitialization by checking the return
5766 // value from pthread_cond_timedwait(). In addition to reinitializing the
5767 // condvar we must establish the invariant that cond_signal() is only called
5768 // within critical sections protected by the adjunct mutex. This prevents
5769 // cond_signal() from "seeing" a condvar that's in the midst of being
5770 // reinitialized or that is corrupt. Sadly, this invariant obviates the
5771 // desirable signal-after-unlock optimization that avoids futile context switching.
5772 //
5773 // I'm also concerned that some versions of NTPL might allocate an auxilliary
5774 // structure when a condvar is used or initialized. cond_destroy() would
5775 // release the helper structure. Our reinitialize-after-timedwait fix
5776 // put excessive stress on malloc/free and locks protecting the c-heap.
5777 //
5778 // We currently use (4). See the WorkAroundNTPLTimedWaitHang flag.
5779 // It may be possible to refine (4) by checking the kernel and NTPL verisons
5780 // and only enabling the work-around for vulnerable environments.
5782 // utility to compute the abstime argument to timedwait:
5783 // millis is the relative timeout time
5784 // abstime will be the absolute timeout time
5785 // TODO: replace compute_abstime() with unpackTime()
5787 static struct timespec* compute_abstime(timespec* abstime, jlong millis) {
5788 if (millis < 0) millis = 0;
5790 jlong seconds = millis / 1000;
5791 millis %= 1000;
5792 if (seconds > 50000000) { // see man cond_timedwait(3T)
5793 seconds = 50000000;
5794 }
5796 if (os::Linux::supports_monotonic_clock()) {
5797 struct timespec now;
5798 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now);
5799 assert_status(status == 0, status, "clock_gettime");
5800 abstime->tv_sec = now.tv_sec + seconds;
5801 long nanos = now.tv_nsec + millis * NANOSECS_PER_MILLISEC;
5802 if (nanos >= NANOSECS_PER_SEC) {
5803 abstime->tv_sec += 1;
5804 nanos -= NANOSECS_PER_SEC;
5805 }
5806 abstime->tv_nsec = nanos;
5807 } else {
5808 struct timeval now;
5809 int status = gettimeofday(&now, NULL);
5810 assert(status == 0, "gettimeofday");
5811 abstime->tv_sec = now.tv_sec + seconds;
5812 long usec = now.tv_usec + millis * 1000;
5813 if (usec >= 1000000) {
5814 abstime->tv_sec += 1;
5815 usec -= 1000000;
5816 }
5817 abstime->tv_nsec = usec * 1000;
5818 }
5819 return abstime;
5820 }
5823 // Test-and-clear _Event, always leaves _Event set to 0, returns immediately.
5824 // Conceptually TryPark() should be equivalent to park(0).
5826 int os::PlatformEvent::TryPark() {
5827 for (;;) {
5828 const int v = _Event ;
5829 guarantee ((v == 0) || (v == 1), "invariant") ;
5830 if (Atomic::cmpxchg (0, &_Event, v) == v) return v ;
5831 }
5832 }
5834 void os::PlatformEvent::park() { // AKA "down()"
5835 // Invariant: Only the thread associated with the Event/PlatformEvent
5836 // may call park().
5837 // TODO: assert that _Assoc != NULL or _Assoc == Self
5838 int v ;
5839 for (;;) {
5840 v = _Event ;
5841 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ;
5842 }
5843 guarantee (v >= 0, "invariant") ;
5844 if (v == 0) {
5845 // Do this the hard way by blocking ...
5846 int status = pthread_mutex_lock(_mutex);
5847 assert_status(status == 0, status, "mutex_lock");
5848 guarantee (_nParked == 0, "invariant") ;
5849 ++ _nParked ;
5850 while (_Event < 0) {
5851 status = pthread_cond_wait(_cond, _mutex);
5852 // for some reason, under 2.7 lwp_cond_wait() may return ETIME ...
5853 // Treat this the same as if the wait was interrupted
5854 if (status == ETIME) { status = EINTR; }
5855 assert_status(status == 0 || status == EINTR, status, "cond_wait");
5856 }
5857 -- _nParked ;
5859 _Event = 0 ;
5860 status = pthread_mutex_unlock(_mutex);
5861 assert_status(status == 0, status, "mutex_unlock");
5862 // Paranoia to ensure our locked and lock-free paths interact
5863 // correctly with each other.
5864 OrderAccess::fence();
5865 }
5866 guarantee (_Event >= 0, "invariant") ;
5867 }
5869 int os::PlatformEvent::park(jlong millis) {
5870 guarantee (_nParked == 0, "invariant") ;
5872 int v ;
5873 for (;;) {
5874 v = _Event ;
5875 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ;
5876 }
5877 guarantee (v >= 0, "invariant") ;
5878 if (v != 0) return OS_OK ;
5880 // We do this the hard way, by blocking the thread.
5881 // Consider enforcing a minimum timeout value.
5882 struct timespec abst;
5883 compute_abstime(&abst, millis);
5885 int ret = OS_TIMEOUT;
5886 int status = pthread_mutex_lock(_mutex);
5887 assert_status(status == 0, status, "mutex_lock");
5888 guarantee (_nParked == 0, "invariant") ;
5889 ++_nParked ;
5891 // Object.wait(timo) will return because of
5892 // (a) notification
5893 // (b) timeout
5894 // (c) thread.interrupt
5895 //
5896 // Thread.interrupt and object.notify{All} both call Event::set.
5897 // That is, we treat thread.interrupt as a special case of notification.
5898 // The underlying Solaris implementation, cond_timedwait, admits
5899 // spurious/premature wakeups, but the JLS/JVM spec prevents the
5900 // JVM from making those visible to Java code. As such, we must
5901 // filter out spurious wakeups. We assume all ETIME returns are valid.
5902 //
5903 // TODO: properly differentiate simultaneous notify+interrupt.
5904 // In that case, we should propagate the notify to another waiter.
5906 while (_Event < 0) {
5907 status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst);
5908 if (status != 0 && WorkAroundNPTLTimedWaitHang) {
5909 pthread_cond_destroy (_cond);
5910 pthread_cond_init (_cond, os::Linux::condAttr()) ;
5911 }
5912 assert_status(status == 0 || status == EINTR ||
5913 status == ETIME || status == ETIMEDOUT,
5914 status, "cond_timedwait");
5915 if (!FilterSpuriousWakeups) break ; // previous semantics
5916 if (status == ETIME || status == ETIMEDOUT) break ;
5917 // We consume and ignore EINTR and spurious wakeups.
5918 }
5919 --_nParked ;
5920 if (_Event >= 0) {
5921 ret = OS_OK;
5922 }
5923 _Event = 0 ;
5924 status = pthread_mutex_unlock(_mutex);
5925 assert_status(status == 0, status, "mutex_unlock");
5926 assert (_nParked == 0, "invariant") ;
5927 // Paranoia to ensure our locked and lock-free paths interact
5928 // correctly with each other.
5929 OrderAccess::fence();
5930 return ret;
5931 }
5933 void os::PlatformEvent::unpark() {
5934 // Transitions for _Event:
5935 // 0 :=> 1
5936 // 1 :=> 1
5937 // -1 :=> either 0 or 1; must signal target thread
5938 // That is, we can safely transition _Event from -1 to either
5939 // 0 or 1. Forcing 1 is slightly more efficient for back-to-back
5940 // unpark() calls.
5941 // See also: "Semaphores in Plan 9" by Mullender & Cox
5942 //
5943 // Note: Forcing a transition from "-1" to "1" on an unpark() means
5944 // that it will take two back-to-back park() calls for the owning
5945 // thread to block. This has the benefit of forcing a spurious return
5946 // from the first park() call after an unpark() call which will help
5947 // shake out uses of park() and unpark() without condition variables.
5949 if (Atomic::xchg(1, &_Event) >= 0) return;
5951 // Wait for the thread associated with the event to vacate
5952 int status = pthread_mutex_lock(_mutex);
5953 assert_status(status == 0, status, "mutex_lock");
5954 int AnyWaiters = _nParked;
5955 assert(AnyWaiters == 0 || AnyWaiters == 1, "invariant");
5956 if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) {
5957 AnyWaiters = 0;
5958 pthread_cond_signal(_cond);
5959 }
5960 status = pthread_mutex_unlock(_mutex);
5961 assert_status(status == 0, status, "mutex_unlock");
5962 if (AnyWaiters != 0) {
5963 status = pthread_cond_signal(_cond);
5964 assert_status(status == 0, status, "cond_signal");
5965 }
5967 // Note that we signal() _after dropping the lock for "immortal" Events.
5968 // This is safe and avoids a common class of futile wakeups. In rare
5969 // circumstances this can cause a thread to return prematurely from
5970 // cond_{timed}wait() but the spurious wakeup is benign and the victim will
5971 // simply re-test the condition and re-park itself.
5972 }
5975 // JSR166
5976 // -------------------------------------------------------
5978 /*
5979 * The solaris and linux implementations of park/unpark are fairly
5980 * conservative for now, but can be improved. They currently use a
5981 * mutex/condvar pair, plus a a count.
5982 * Park decrements count if > 0, else does a condvar wait. Unpark
5983 * sets count to 1 and signals condvar. Only one thread ever waits
5984 * on the condvar. Contention seen when trying to park implies that someone
5985 * is unparking you, so don't wait. And spurious returns are fine, so there
5986 * is no need to track notifications.
5987 */
5989 /*
5990 * This code is common to linux and solaris and will be moved to a
5991 * common place in dolphin.
5992 *
5993 * The passed in time value is either a relative time in nanoseconds
5994 * or an absolute time in milliseconds. Either way it has to be unpacked
5995 * into suitable seconds and nanoseconds components and stored in the
5996 * given timespec structure.
5997 * Given time is a 64-bit value and the time_t used in the timespec is only
5998 * a signed-32-bit value (except on 64-bit Linux) we have to watch for
5999 * overflow if times way in the future are given. Further on Solaris versions
6000 * prior to 10 there is a restriction (see cond_timedwait) that the specified
6001 * number of seconds, in abstime, is less than current_time + 100,000,000.
6002 * As it will be 28 years before "now + 100000000" will overflow we can
6003 * ignore overflow and just impose a hard-limit on seconds using the value
6004 * of "now + 100,000,000". This places a limit on the timeout of about 3.17
6005 * years from "now".
6006 */
6008 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) {
6009 assert (time > 0, "convertTime");
6010 time_t max_secs = 0;
6012 if (!os::Linux::supports_monotonic_clock() || isAbsolute) {
6013 struct timeval now;
6014 int status = gettimeofday(&now, NULL);
6015 assert(status == 0, "gettimeofday");
6017 max_secs = now.tv_sec + MAX_SECS;
6019 if (isAbsolute) {
6020 jlong secs = time / 1000;
6021 if (secs > max_secs) {
6022 absTime->tv_sec = max_secs;
6023 } else {
6024 absTime->tv_sec = secs;
6025 }
6026 absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC;
6027 } else {
6028 jlong secs = time / NANOSECS_PER_SEC;
6029 if (secs >= MAX_SECS) {
6030 absTime->tv_sec = max_secs;
6031 absTime->tv_nsec = 0;
6032 } else {
6033 absTime->tv_sec = now.tv_sec + secs;
6034 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000;
6035 if (absTime->tv_nsec >= NANOSECS_PER_SEC) {
6036 absTime->tv_nsec -= NANOSECS_PER_SEC;
6037 ++absTime->tv_sec; // note: this must be <= max_secs
6038 }
6039 }
6040 }
6041 } else {
6042 // must be relative using monotonic clock
6043 struct timespec now;
6044 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now);
6045 assert_status(status == 0, status, "clock_gettime");
6046 max_secs = now.tv_sec + MAX_SECS;
6047 jlong secs = time / NANOSECS_PER_SEC;
6048 if (secs >= MAX_SECS) {
6049 absTime->tv_sec = max_secs;
6050 absTime->tv_nsec = 0;
6051 } else {
6052 absTime->tv_sec = now.tv_sec + secs;
6053 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_nsec;
6054 if (absTime->tv_nsec >= NANOSECS_PER_SEC) {
6055 absTime->tv_nsec -= NANOSECS_PER_SEC;
6056 ++absTime->tv_sec; // note: this must be <= max_secs
6057 }
6058 }
6059 }
6060 assert(absTime->tv_sec >= 0, "tv_sec < 0");
6061 assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs");
6062 assert(absTime->tv_nsec >= 0, "tv_nsec < 0");
6063 assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec");
6064 }
6066 void Parker::park(bool isAbsolute, jlong time) {
6067 // Ideally we'd do something useful while spinning, such
6068 // as calling unpackTime().
6070 // Optional fast-path check:
6071 // Return immediately if a permit is available.
6072 // We depend on Atomic::xchg() having full barrier semantics
6073 // since we are doing a lock-free update to _counter.
6074 if (Atomic::xchg(0, &_counter) > 0) return;
6076 Thread* thread = Thread::current();
6077 assert(thread->is_Java_thread(), "Must be JavaThread");
6078 JavaThread *jt = (JavaThread *)thread;
6080 // Optional optimization -- avoid state transitions if there's an interrupt pending.
6081 // Check interrupt before trying to wait
6082 if (Thread::is_interrupted(thread, false)) {
6083 return;
6084 }
6086 // Next, demultiplex/decode time arguments
6087 timespec absTime;
6088 if (time < 0 || (isAbsolute && time == 0) ) { // don't wait at all
6089 return;
6090 }
6091 if (time > 0) {
6092 unpackTime(&absTime, isAbsolute, time);
6093 }
6096 // Enter safepoint region
6097 // Beware of deadlocks such as 6317397.
6098 // The per-thread Parker:: mutex is a classic leaf-lock.
6099 // In particular a thread must never block on the Threads_lock while
6100 // holding the Parker:: mutex. If safepoints are pending both the
6101 // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock.
6102 ThreadBlockInVM tbivm(jt);
6104 // Don't wait if cannot get lock since interference arises from
6105 // unblocking. Also. check interrupt before trying wait
6106 if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) {
6107 return;
6108 }
6110 int status ;
6111 if (_counter > 0) { // no wait needed
6112 _counter = 0;
6113 status = pthread_mutex_unlock(_mutex);
6114 assert (status == 0, "invariant") ;
6115 // Paranoia to ensure our locked and lock-free paths interact
6116 // correctly with each other and Java-level accesses.
6117 OrderAccess::fence();
6118 return;
6119 }
6121 #ifdef ASSERT
6122 // Don't catch signals while blocked; let the running threads have the signals.
6123 // (This allows a debugger to break into the running thread.)
6124 sigset_t oldsigs;
6125 sigset_t* allowdebug_blocked = os::Linux::allowdebug_blocked_signals();
6126 pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs);
6127 #endif
6129 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */);
6130 jt->set_suspend_equivalent();
6131 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
6133 assert(_cur_index == -1, "invariant");
6134 if (time == 0) {
6135 _cur_index = REL_INDEX; // arbitrary choice when not timed
6136 status = pthread_cond_wait (&_cond[_cur_index], _mutex) ;
6137 } else {
6138 _cur_index = isAbsolute ? ABS_INDEX : REL_INDEX;
6139 status = os::Linux::safe_cond_timedwait (&_cond[_cur_index], _mutex, &absTime) ;
6140 if (status != 0 && WorkAroundNPTLTimedWaitHang) {
6141 pthread_cond_destroy (&_cond[_cur_index]) ;
6142 pthread_cond_init (&_cond[_cur_index], isAbsolute ? NULL : os::Linux::condAttr());
6143 }
6144 }
6145 _cur_index = -1;
6146 assert_status(status == 0 || status == EINTR ||
6147 status == ETIME || status == ETIMEDOUT,
6148 status, "cond_timedwait");
6150 #ifdef ASSERT
6151 pthread_sigmask(SIG_SETMASK, &oldsigs, NULL);
6152 #endif
6154 _counter = 0 ;
6155 status = pthread_mutex_unlock(_mutex) ;
6156 assert_status(status == 0, status, "invariant") ;
6157 // Paranoia to ensure our locked and lock-free paths interact
6158 // correctly with each other and Java-level accesses.
6159 OrderAccess::fence();
6161 // If externally suspended while waiting, re-suspend
6162 if (jt->handle_special_suspend_equivalent_condition()) {
6163 jt->java_suspend_self();
6164 }
6165 }
6167 void Parker::unpark() {
6168 int s, status ;
6169 status = pthread_mutex_lock(_mutex);
6170 assert (status == 0, "invariant") ;
6171 s = _counter;
6172 _counter = 1;
6173 if (s < 1) {
6174 // thread might be parked
6175 if (_cur_index != -1) {
6176 // thread is definitely parked
6177 if (WorkAroundNPTLTimedWaitHang) {
6178 status = pthread_cond_signal (&_cond[_cur_index]);
6179 assert (status == 0, "invariant");
6180 status = pthread_mutex_unlock(_mutex);
6181 assert (status == 0, "invariant");
6182 } else {
6183 // must capture correct index before unlocking
6184 int index = _cur_index;
6185 status = pthread_mutex_unlock(_mutex);
6186 assert (status == 0, "invariant");
6187 status = pthread_cond_signal (&_cond[index]);
6188 assert (status == 0, "invariant");
6189 }
6190 } else {
6191 pthread_mutex_unlock(_mutex);
6192 assert (status == 0, "invariant") ;
6193 }
6194 } else {
6195 pthread_mutex_unlock(_mutex);
6196 assert (status == 0, "invariant") ;
6197 }
6198 }
6201 extern char** environ;
6203 // Run the specified command in a separate process. Return its exit value,
6204 // or -1 on failure (e.g. can't fork a new process).
6205 // Unlike system(), this function can be called from signal handler. It
6206 // doesn't block SIGINT et al.
6207 int os::fork_and_exec(char* cmd) {
6208 const char * argv[4] = {"sh", "-c", cmd, NULL};
6210 pid_t pid = fork();
6212 if (pid < 0) {
6213 // fork failed
6214 return -1;
6216 } else if (pid == 0) {
6217 // child process
6219 execve("/bin/sh", (char* const*)argv, environ);
6221 // execve failed
6222 _exit(-1);
6224 } else {
6225 // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't
6226 // care about the actual exit code, for now.
6228 int status;
6230 // Wait for the child process to exit. This returns immediately if
6231 // the child has already exited. */
6232 while (waitpid(pid, &status, 0) < 0) {
6233 switch (errno) {
6234 case ECHILD: return 0;
6235 case EINTR: break;
6236 default: return -1;
6237 }
6238 }
6240 if (WIFEXITED(status)) {
6241 // The child exited normally; get its exit code.
6242 return WEXITSTATUS(status);
6243 } else if (WIFSIGNALED(status)) {
6244 // The child exited because of a signal
6245 // The best value to return is 0x80 + signal number,
6246 // because that is what all Unix shells do, and because
6247 // it allows callers to distinguish between process exit and
6248 // process death by signal.
6249 return 0x80 + WTERMSIG(status);
6250 } else {
6251 // Unknown exit code; pass it through
6252 return status;
6253 }
6254 }
6255 }
6257 // is_headless_jre()
6258 //
6259 // Test for the existence of xawt/libmawt.so or libawt_xawt.so
6260 // in order to report if we are running in a headless jre
6261 //
6262 // Since JDK8 xawt/libmawt.so was moved into the same directory
6263 // as libawt.so, and renamed libawt_xawt.so
6264 //
6265 bool os::is_headless_jre() {
6266 struct stat statbuf;
6267 char buf[MAXPATHLEN];
6268 char libmawtpath[MAXPATHLEN];
6269 const char *xawtstr = "/xawt/libmawt.so";
6270 const char *new_xawtstr = "/libawt_xawt.so";
6271 char *p;
6273 // Get path to libjvm.so
6274 os::jvm_path(buf, sizeof(buf));
6276 // Get rid of libjvm.so
6277 p = strrchr(buf, '/');
6278 if (p == NULL) return false;
6279 else *p = '\0';
6281 // Get rid of client or server
6282 p = strrchr(buf, '/');
6283 if (p == NULL) return false;
6284 else *p = '\0';
6286 // check xawt/libmawt.so
6287 strcpy(libmawtpath, buf);
6288 strcat(libmawtpath, xawtstr);
6289 if (::stat(libmawtpath, &statbuf) == 0) return false;
6291 // check libawt_xawt.so
6292 strcpy(libmawtpath, buf);
6293 strcat(libmawtpath, new_xawtstr);
6294 if (::stat(libmawtpath, &statbuf) == 0) return false;
6296 return true;
6297 }
6299 // Get the default path to the core file
6300 // Returns the length of the string
6301 int os::get_core_path(char* buffer, size_t bufferSize) {
6302 const char* p = get_current_directory(buffer, bufferSize);
6304 if (p == NULL) {
6305 assert(p != NULL, "failed to get current directory");
6306 return 0;
6307 }
6309 return strlen(buffer);
6310 }
6312 /////////////// Unit tests ///////////////
6314 #ifndef PRODUCT
6316 #define test_log(...) \
6317 do {\
6318 if (VerboseInternalVMTests) { \
6319 tty->print_cr(__VA_ARGS__); \
6320 tty->flush(); \
6321 }\
6322 } while (false)
6324 class TestReserveMemorySpecial : AllStatic {
6325 public:
6326 static void small_page_write(void* addr, size_t size) {
6327 size_t page_size = os::vm_page_size();
6329 char* end = (char*)addr + size;
6330 for (char* p = (char*)addr; p < end; p += page_size) {
6331 *p = 1;
6332 }
6333 }
6335 static void test_reserve_memory_special_huge_tlbfs_only(size_t size) {
6336 if (!UseHugeTLBFS) {
6337 return;
6338 }
6340 test_log("test_reserve_memory_special_huge_tlbfs_only(" SIZE_FORMAT ")", size);
6342 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_only(size, NULL, false);
6344 if (addr != NULL) {
6345 small_page_write(addr, size);
6347 os::Linux::release_memory_special_huge_tlbfs(addr, size);
6348 }
6349 }
6351 static void test_reserve_memory_special_huge_tlbfs_only() {
6352 if (!UseHugeTLBFS) {
6353 return;
6354 }
6356 size_t lp = os::large_page_size();
6358 for (size_t size = lp; size <= lp * 10; size += lp) {
6359 test_reserve_memory_special_huge_tlbfs_only(size);
6360 }
6361 }
6363 static void test_reserve_memory_special_huge_tlbfs_mixed() {
6364 size_t lp = os::large_page_size();
6365 size_t ag = os::vm_allocation_granularity();
6367 // sizes to test
6368 const size_t sizes[] = {
6369 lp, lp + ag, lp + lp / 2, lp * 2,
6370 lp * 2 + ag, lp * 2 - ag, lp * 2 + lp / 2,
6371 lp * 10, lp * 10 + lp / 2
6372 };
6373 const int num_sizes = sizeof(sizes) / sizeof(size_t);
6375 // For each size/alignment combination, we test three scenarios:
6376 // 1) with req_addr == NULL
6377 // 2) with a non-null req_addr at which we expect to successfully allocate
6378 // 3) with a non-null req_addr which contains a pre-existing mapping, at which we
6379 // expect the allocation to either fail or to ignore req_addr
6381 // Pre-allocate two areas; they shall be as large as the largest allocation
6382 // and aligned to the largest alignment we will be testing.
6383 const size_t mapping_size = sizes[num_sizes - 1] * 2;
6384 char* const mapping1 = (char*) ::mmap(NULL, mapping_size,
6385 PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE,
6386 -1, 0);
6387 assert(mapping1 != MAP_FAILED, "should work");
6389 char* const mapping2 = (char*) ::mmap(NULL, mapping_size,
6390 PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE,
6391 -1, 0);
6392 assert(mapping2 != MAP_FAILED, "should work");
6394 // Unmap the first mapping, but leave the second mapping intact: the first
6395 // mapping will serve as a value for a "good" req_addr (case 2). The second
6396 // mapping, still intact, as "bad" req_addr (case 3).
6397 ::munmap(mapping1, mapping_size);
6399 // Case 1
6400 test_log("%s, req_addr NULL:", __FUNCTION__);
6401 test_log("size align result");
6403 for (int i = 0; i < num_sizes; i++) {
6404 const size_t size = sizes[i];
6405 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) {
6406 char* p = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, NULL, false);
6407 test_log(SIZE_FORMAT_HEX " " SIZE_FORMAT_HEX " -> " PTR_FORMAT " %s",
6408 size, alignment, p, (p != NULL ? "" : "(failed)"));
6409 if (p != NULL) {
6410 assert(is_ptr_aligned(p, alignment), "must be");
6411 small_page_write(p, size);
6412 os::Linux::release_memory_special_huge_tlbfs(p, size);
6413 }
6414 }
6415 }
6417 // Case 2
6418 test_log("%s, req_addr non-NULL:", __FUNCTION__);
6419 test_log("size align req_addr result");
6421 for (int i = 0; i < num_sizes; i++) {
6422 const size_t size = sizes[i];
6423 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) {
6424 char* const req_addr = (char*) align_ptr_up(mapping1, alignment);
6425 char* p = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, req_addr, false);
6426 test_log(SIZE_FORMAT_HEX " " SIZE_FORMAT_HEX " " PTR_FORMAT " -> " PTR_FORMAT " %s",
6427 size, alignment, req_addr, p,
6428 ((p != NULL ? (p == req_addr ? "(exact match)" : "") : "(failed)")));
6429 if (p != NULL) {
6430 assert(p == req_addr, "must be");
6431 small_page_write(p, size);
6432 os::Linux::release_memory_special_huge_tlbfs(p, size);
6433 }
6434 }
6435 }
6437 // Case 3
6438 test_log("%s, req_addr non-NULL with preexisting mapping:", __FUNCTION__);
6439 test_log("size align req_addr result");
6441 for (int i = 0; i < num_sizes; i++) {
6442 const size_t size = sizes[i];
6443 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) {
6444 char* const req_addr = (char*) align_ptr_up(mapping2, alignment);
6445 char* p = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, req_addr, false);
6446 test_log(SIZE_FORMAT_HEX " " SIZE_FORMAT_HEX " " PTR_FORMAT " -> " PTR_FORMAT " %s",
6447 size, alignment, req_addr, p,
6448 ((p != NULL ? "" : "(failed)")));
6449 // as the area around req_addr contains already existing mappings, the API should always
6450 // return NULL (as per contract, it cannot return another address)
6451 assert(p == NULL, "must be");
6452 }
6453 }
6455 ::munmap(mapping2, mapping_size);
6457 }
6459 static void test_reserve_memory_special_huge_tlbfs() {
6460 if (!UseHugeTLBFS) {
6461 return;
6462 }
6464 test_reserve_memory_special_huge_tlbfs_only();
6465 test_reserve_memory_special_huge_tlbfs_mixed();
6466 }
6468 static void test_reserve_memory_special_shm(size_t size, size_t alignment) {
6469 if (!UseSHM) {
6470 return;
6471 }
6473 test_log("test_reserve_memory_special_shm(" SIZE_FORMAT ", " SIZE_FORMAT ")", size, alignment);
6475 char* addr = os::Linux::reserve_memory_special_shm(size, alignment, NULL, false);
6477 if (addr != NULL) {
6478 assert(is_ptr_aligned(addr, alignment), "Check");
6479 assert(is_ptr_aligned(addr, os::large_page_size()), "Check");
6481 small_page_write(addr, size);
6483 os::Linux::release_memory_special_shm(addr, size);
6484 }
6485 }
6487 static void test_reserve_memory_special_shm() {
6488 size_t lp = os::large_page_size();
6489 size_t ag = os::vm_allocation_granularity();
6491 for (size_t size = ag; size < lp * 3; size += ag) {
6492 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) {
6493 test_reserve_memory_special_shm(size, alignment);
6494 }
6495 }
6496 }
6498 static void test() {
6499 test_reserve_memory_special_huge_tlbfs();
6500 test_reserve_memory_special_shm();
6501 }
6502 };
6504 void TestReserveMemorySpecial_test() {
6505 TestReserveMemorySpecial::test();
6506 }
6508 #endif