1 /*
2 * Copyright (c) 1999, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 // no precompiled headers
26 #include "classfile/classLoader.hpp"
27 #include "classfile/systemDictionary.hpp"
28 #include "classfile/vmSymbols.hpp"
29 #include "code/icBuffer.hpp"
30 #include "code/vtableStubs.hpp"
31 #include "compiler/compileBroker.hpp"
32 #include "compiler/disassembler.hpp"
33 #include "interpreter/interpreter.hpp"
34 #include "jvm_linux.h"
35 #include "memory/allocation.inline.hpp"
36 #include "memory/filemap.hpp"
37 #include "mutex_linux.inline.hpp"
38 #include "oops/oop.inline.hpp"
39 #include "os_linux.inline.hpp"
40 #include "os_share_linux.hpp"
41 #include "prims/jniFastGetField.hpp"
42 #include "prims/jvm.h"
43 #include "prims/jvm_misc.hpp"
44 #include "runtime/arguments.hpp"
45 #include "runtime/atomic.inline.hpp"
46 #include "runtime/extendedPC.hpp"
47 #include "runtime/globals.hpp"
48 #include "runtime/interfaceSupport.hpp"
49 #include "runtime/init.hpp"
50 #include "runtime/java.hpp"
51 #include "runtime/javaCalls.hpp"
52 #include "runtime/mutexLocker.hpp"
53 #include "runtime/objectMonitor.hpp"
54 #include "runtime/orderAccess.inline.hpp"
55 #include "runtime/osThread.hpp"
56 #include "runtime/perfMemory.hpp"
57 #include "runtime/sharedRuntime.hpp"
58 #include "runtime/statSampler.hpp"
59 #include "runtime/stubRoutines.hpp"
60 #include "runtime/thread.inline.hpp"
61 #include "runtime/threadCritical.hpp"
62 #include "runtime/timer.hpp"
63 #include "services/attachListener.hpp"
64 #include "services/memTracker.hpp"
65 #include "services/runtimeService.hpp"
66 #include "utilities/decoder.hpp"
67 #include "utilities/defaultStream.hpp"
68 #include "utilities/events.hpp"
69 #include "utilities/elfFile.hpp"
70 #include "utilities/growableArray.hpp"
71 #include "utilities/macros.hpp"
72 #include "utilities/vmError.hpp"
73
74 // put OS-includes here
75 # include <sys/types.h>
76 # include <sys/mman.h>
77 # include <sys/stat.h>
78 # include <sys/select.h>
79 # include <pthread.h>
80 # include <signal.h>
81 # include <errno.h>
82 # include <dlfcn.h>
83 # include <stdio.h>
84 # include <unistd.h>
85 # include <sys/resource.h>
86 # include <pthread.h>
87 # include <sys/stat.h>
88 # include <sys/time.h>
89 # include <sys/times.h>
90 # include <sys/utsname.h>
91 # include <sys/socket.h>
92 # include <sys/wait.h>
93 # include <pwd.h>
94 # include <poll.h>
95 # include <semaphore.h>
96 # include <fcntl.h>
97 # include <string.h>
98 # include <syscall.h>
99 # include <sys/sysinfo.h>
100 # include <gnu/libc-version.h>
101 # include <sys/ipc.h>
102 # include <sys/shm.h>
103 # include <link.h>
104 # include <stdint.h>
105 # include <inttypes.h>
106 # include <sys/ioctl.h>
107
108 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
109
110 // if RUSAGE_THREAD for getrusage() has not been defined, do it here. The code calling
111 // getrusage() is prepared to handle the associated failure.
112 #ifndef RUSAGE_THREAD
113 #define RUSAGE_THREAD (1) /* only the calling thread */
114 #endif
115
116 #define MAX_PATH (2 * K)
117
118 #define MAX_SECS 100000000
119
120 // for timer info max values which include all bits
121 #define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF)
122
123 #define LARGEPAGES_BIT (1 << 6)
124 ////////////////////////////////////////////////////////////////////////////////
125 // global variables
126 julong os::Linux::_physical_memory = 0;
127
128 address os::Linux::_initial_thread_stack_bottom = NULL;
129 uintptr_t os::Linux::_initial_thread_stack_size = 0;
130
131 int (*os::Linux::_clock_gettime)(clockid_t, struct timespec *) = NULL;
132 int (*os::Linux::_pthread_getcpuclockid)(pthread_t, clockid_t *) = NULL;
133 int (*os::Linux::_pthread_setname_np)(pthread_t, const char*) = NULL;
134 Mutex* os::Linux::_createThread_lock = NULL;
135 pthread_t os::Linux::_main_thread;
136 int os::Linux::_page_size = -1;
137 const int os::Linux::_vm_default_page_size = (8 * K);
138 bool os::Linux::_is_floating_stack = false;
139 bool os::Linux::_is_NPTL = false;
140 bool os::Linux::_supports_fast_thread_cpu_time = false;
141 const char * os::Linux::_glibc_version = NULL;
142 const char * os::Linux::_libpthread_version = NULL;
143 pthread_condattr_t os::Linux::_condattr[1];
144
145 static jlong initial_time_count=0;
146
147 static int clock_tics_per_sec = 100;
148
149 // For diagnostics to print a message once. see run_periodic_checks
150 static sigset_t check_signal_done;
151 static bool check_signals = true;
152
153 static pid_t _initial_pid = 0;
154
155 // Signal number used to suspend/resume a thread
156
157 // do not use any signal number less than SIGSEGV, see 4355769
158 static int SR_signum = SIGUSR2;
159 sigset_t SR_sigset;
160
161 // Used to protect dlsym() calls
162 static pthread_mutex_t dl_mutex;
163
164 // Declarations
165 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time);
166
167 // utility functions
168
169 static int SR_initialize();
170
171 julong os::available_memory() {
172 return Linux::available_memory();
173 }
174
175 julong os::Linux::available_memory() {
176 // values in struct sysinfo are "unsigned long"
177 struct sysinfo si;
178 sysinfo(&si);
179
180 return (julong)si.freeram * si.mem_unit;
181 }
182
183 julong os::physical_memory() {
184 return Linux::physical_memory();
185 }
186
187 ////////////////////////////////////////////////////////////////////////////////
188 // environment support
189
190 bool os::getenv(const char* name, char* buf, int len) {
191 const char* val = ::getenv(name);
192 if (val != NULL && strlen(val) < (size_t)len) {
193 strcpy(buf, val);
194 return true;
195 }
196 if (len > 0) buf[0] = 0; // return a null string
197 return false;
198 }
199
200
201 // Return true if user is running as root.
202
203 bool os::have_special_privileges() {
204 static bool init = false;
205 static bool privileges = false;
206 if (!init) {
207 privileges = (getuid() != geteuid()) || (getgid() != getegid());
208 init = true;
209 }
210 return privileges;
211 }
212
213
214 #ifndef SYS_gettid
215 // i386: 224, ia64: 1105, amd64: 186, sparc 143
216 #ifdef __ia64__
217 #define SYS_gettid 1105
218 #elif __i386__
219 #define SYS_gettid 224
220 #elif __amd64__
221 #define SYS_gettid 186
222 #elif __sparc__
223 #define SYS_gettid 143
224 #else
225 #error define gettid for the arch
226 #endif
227 #endif
228
229 // Cpu architecture string
230 #if defined(ZERO)
231 static char cpu_arch[] = ZERO_LIBARCH;
232 #elif defined(IA64)
233 static char cpu_arch[] = "ia64";
234 #elif defined(IA32)
235 static char cpu_arch[] = "i386";
236 #elif defined(AMD64)
237 static char cpu_arch[] = "amd64";
238 #elif defined(ARM)
239 static char cpu_arch[] = "arm";
240 #elif defined(PPC32)
241 static char cpu_arch[] = "ppc";
242 #elif defined(PPC64)
243 static char cpu_arch[] = "ppc64";
244 #elif defined(SPARC)
245 #ifdef _LP64
246 static char cpu_arch[] = "sparcv9";
247 #else
248 static char cpu_arch[] = "sparc";
249 #endif
250 #else
251 #error Add appropriate cpu_arch setting
252 #endif
253
254
255 // pid_t gettid()
256 //
257 // Returns the kernel thread id of the currently running thread. Kernel
258 // thread id is used to access /proc.
259 //
260 // (Note that getpid() on LinuxThreads returns kernel thread id too; but
261 // on NPTL, it returns the same pid for all threads, as required by POSIX.)
262 //
263 pid_t os::Linux::gettid() {
264 int rslt = syscall(SYS_gettid);
265 if (rslt == -1) {
266 // old kernel, no NPTL support
267 return getpid();
268 } else {
269 return (pid_t)rslt;
270 }
271 }
272
273 // Most versions of linux have a bug where the number of processors are
274 // determined by looking at the /proc file system. In a chroot environment,
275 // the system call returns 1. This causes the VM to act as if it is
276 // a single processor and elide locking (see is_MP() call).
277 static bool unsafe_chroot_detected = false;
278 static const char *unstable_chroot_error = "/proc file system not found.\n"
279 "Java may be unstable running multithreaded in a chroot "
280 "environment on Linux when /proc filesystem is not mounted.";
281
282 void os::Linux::initialize_system_info() {
283 set_processor_count(sysconf(_SC_NPROCESSORS_CONF));
284 if (processor_count() == 1) {
285 pid_t pid = os::Linux::gettid();
286 char fname[32];
287 jio_snprintf(fname, sizeof(fname), "/proc/%d", pid);
288 FILE *fp = fopen(fname, "r");
289 if (fp == NULL) {
290 unsafe_chroot_detected = true;
291 } else {
292 fclose(fp);
293 }
294 }
295 _physical_memory = (julong)sysconf(_SC_PHYS_PAGES) * (julong)sysconf(_SC_PAGESIZE);
296 assert(processor_count() > 0, "linux error");
297 }
298
299 void os::init_system_properties_values() {
300 // The next steps are taken in the product version:
301 //
302 // Obtain the JAVA_HOME value from the location of libjvm.so.
303 // This library should be located at:
304 // <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm.so.
305 //
306 // If "/jre/lib/" appears at the right place in the path, then we
307 // assume libjvm.so is installed in a JDK and we use this path.
308 //
309 // Otherwise exit with message: "Could not create the Java virtual machine."
310 //
311 // The following extra steps are taken in the debugging version:
312 //
313 // If "/jre/lib/" does NOT appear at the right place in the path
314 // instead of exit check for $JAVA_HOME environment variable.
315 //
316 // If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>,
317 // then we append a fake suffix "hotspot/libjvm.so" to this path so
318 // it looks like libjvm.so is installed there
319 // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm.so.
320 //
321 // Otherwise exit.
322 //
323 // Important note: if the location of libjvm.so changes this
324 // code needs to be changed accordingly.
325
326 // See ld(1):
327 // The linker uses the following search paths to locate required
328 // shared libraries:
329 // 1: ...
330 // ...
331 // 7: The default directories, normally /lib and /usr/lib.
332 #if defined(AMD64) || defined(_LP64) && (defined(SPARC) || defined(PPC) || defined(S390))
333 #define DEFAULT_LIBPATH "/usr/lib64:/lib64:/lib:/usr/lib"
334 #else
335 #define DEFAULT_LIBPATH "/lib:/usr/lib"
336 #endif
337
338 // Base path of extensions installed on the system.
339 #define SYS_EXT_DIR "/usr/java/packages"
340 #define EXTENSIONS_DIR "/lib/ext"
341
342 // Buffer that fits several sprintfs.
343 // Note that the space for the colon and the trailing null are provided
344 // by the nulls included by the sizeof operator.
345 const size_t bufsize =
346 MAX2((size_t)MAXPATHLEN, // For dll_dir & friends.
347 (size_t)MAXPATHLEN + sizeof(EXTENSIONS_DIR) + sizeof(SYS_EXT_DIR) + sizeof(EXTENSIONS_DIR)); // extensions dir
348 char *buf = (char *)NEW_C_HEAP_ARRAY(char, bufsize, mtInternal);
349
350 // sysclasspath, java_home, dll_dir
351 {
352 char *pslash;
353 os::jvm_path(buf, bufsize);
354
355 // Found the full path to libjvm.so.
356 // Now cut the path to <java_home>/jre if we can.
357 pslash = strrchr(buf, '/');
358 if (pslash != NULL) {
359 *pslash = '\0'; // Get rid of /libjvm.so.
360 }
361 pslash = strrchr(buf, '/');
362 if (pslash != NULL) {
363 *pslash = '\0'; // Get rid of /{client|server|hotspot}.
364 }
365 Arguments::set_dll_dir(buf);
366
367 if (pslash != NULL) {
368 pslash = strrchr(buf, '/');
369 if (pslash != NULL) {
370 *pslash = '\0'; // Get rid of /<arch>.
371 pslash = strrchr(buf, '/');
372 if (pslash != NULL) {
373 *pslash = '\0'; // Get rid of /lib.
374 }
375 }
376 }
377 Arguments::set_java_home(buf);
378 set_boot_path('/', ':');
379 }
380
381 // Where to look for native libraries.
382 //
383 // Note: Due to a legacy implementation, most of the library path
384 // is set in the launcher. This was to accomodate linking restrictions
385 // on legacy Linux implementations (which are no longer supported).
386 // Eventually, all the library path setting will be done here.
387 //
388 // However, to prevent the proliferation of improperly built native
389 // libraries, the new path component /usr/java/packages is added here.
390 // Eventually, all the library path setting will be done here.
391 {
392 // Get the user setting of LD_LIBRARY_PATH, and prepended it. It
393 // should always exist (until the legacy problem cited above is
394 // addressed).
395 const char *v = ::getenv("LD_LIBRARY_PATH");
396 const char *v_colon = ":";
397 if (v == NULL) { v = ""; v_colon = ""; }
398 // That's +1 for the colon and +1 for the trailing '\0'.
399 char *ld_library_path = (char *)NEW_C_HEAP_ARRAY(char,
400 strlen(v) + 1 +
401 sizeof(SYS_EXT_DIR) + sizeof("/lib/") + strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH) + 1,
402 mtInternal);
403 sprintf(ld_library_path, "%s%s" SYS_EXT_DIR "/lib/%s:" DEFAULT_LIBPATH, v, v_colon, cpu_arch);
404 Arguments::set_library_path(ld_library_path);
405 FREE_C_HEAP_ARRAY(char, ld_library_path);
406 }
407
408 // Extensions directories.
409 sprintf(buf, "%s" EXTENSIONS_DIR ":" SYS_EXT_DIR EXTENSIONS_DIR, Arguments::get_java_home());
410 Arguments::set_ext_dirs(buf);
411
412 FREE_C_HEAP_ARRAY(char, buf);
413
414 #undef DEFAULT_LIBPATH
415 #undef SYS_EXT_DIR
416 #undef EXTENSIONS_DIR
417 }
418
419 ////////////////////////////////////////////////////////////////////////////////
420 // breakpoint support
421
422 void os::breakpoint() {
423 BREAKPOINT;
424 }
425
426 extern "C" void breakpoint() {
427 // use debugger to set breakpoint here
428 }
429
430 ////////////////////////////////////////////////////////////////////////////////
431 // signal support
432
433 debug_only(static bool signal_sets_initialized = false);
434 static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs;
435
436 bool os::Linux::is_sig_ignored(int sig) {
437 struct sigaction oact;
438 sigaction(sig, (struct sigaction*)NULL, &oact);
439 void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*, oact.sa_sigaction)
440 : CAST_FROM_FN_PTR(void*, oact.sa_handler);
441 if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN)) {
442 return true;
443 } else {
444 return false;
445 }
446 }
447
448 void os::Linux::signal_sets_init() {
449 // Should also have an assertion stating we are still single-threaded.
450 assert(!signal_sets_initialized, "Already initialized");
451 // Fill in signals that are necessarily unblocked for all threads in
452 // the VM. Currently, we unblock the following signals:
453 // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden
454 // by -Xrs (=ReduceSignalUsage));
455 // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all
456 // other threads. The "ReduceSignalUsage" boolean tells us not to alter
457 // the dispositions or masks wrt these signals.
458 // Programs embedding the VM that want to use the above signals for their
459 // own purposes must, at this time, use the "-Xrs" option to prevent
460 // interference with shutdown hooks and BREAK_SIGNAL thread dumping.
461 // (See bug 4345157, and other related bugs).
462 // In reality, though, unblocking these signals is really a nop, since
463 // these signals are not blocked by default.
464 sigemptyset(&unblocked_sigs);
465 sigemptyset(&allowdebug_blocked_sigs);
466 sigaddset(&unblocked_sigs, SIGILL);
467 sigaddset(&unblocked_sigs, SIGSEGV);
468 sigaddset(&unblocked_sigs, SIGBUS);
469 sigaddset(&unblocked_sigs, SIGFPE);
470 #if defined(PPC64)
471 sigaddset(&unblocked_sigs, SIGTRAP);
472 #endif
473 sigaddset(&unblocked_sigs, SR_signum);
474
475 if (!ReduceSignalUsage) {
476 if (!os::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) {
477 sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL);
478 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL);
479 }
480 if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) {
481 sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL);
482 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL);
483 }
484 if (!os::Linux::is_sig_ignored(SHUTDOWN3_SIGNAL)) {
485 sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL);
486 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN3_SIGNAL);
487 }
488 }
489 // Fill in signals that are blocked by all but the VM thread.
490 sigemptyset(&vm_sigs);
491 if (!ReduceSignalUsage) {
492 sigaddset(&vm_sigs, BREAK_SIGNAL);
493 }
494 debug_only(signal_sets_initialized = true);
495
496 }
497
498 // These are signals that are unblocked while a thread is running Java.
499 // (For some reason, they get blocked by default.)
500 sigset_t* os::Linux::unblocked_signals() {
501 assert(signal_sets_initialized, "Not initialized");
502 return &unblocked_sigs;
503 }
504
505 // These are the signals that are blocked while a (non-VM) thread is
506 // running Java. Only the VM thread handles these signals.
507 sigset_t* os::Linux::vm_signals() {
508 assert(signal_sets_initialized, "Not initialized");
509 return &vm_sigs;
510 }
511
512 // These are signals that are blocked during cond_wait to allow debugger in
513 sigset_t* os::Linux::allowdebug_blocked_signals() {
514 assert(signal_sets_initialized, "Not initialized");
515 return &allowdebug_blocked_sigs;
516 }
517
518 void os::Linux::hotspot_sigmask(Thread* thread) {
519
520 //Save caller's signal mask before setting VM signal mask
521 sigset_t caller_sigmask;
522 pthread_sigmask(SIG_BLOCK, NULL, &caller_sigmask);
523
524 OSThread* osthread = thread->osthread();
525 osthread->set_caller_sigmask(caller_sigmask);
526
527 pthread_sigmask(SIG_UNBLOCK, os::Linux::unblocked_signals(), NULL);
528
529 if (!ReduceSignalUsage) {
530 if (thread->is_VM_thread()) {
531 // Only the VM thread handles BREAK_SIGNAL ...
532 pthread_sigmask(SIG_UNBLOCK, vm_signals(), NULL);
533 } else {
534 // ... all other threads block BREAK_SIGNAL
535 pthread_sigmask(SIG_BLOCK, vm_signals(), NULL);
536 }
537 }
538 }
539
540 //////////////////////////////////////////////////////////////////////////////
541 // detecting pthread library
542
543 void os::Linux::libpthread_init() {
544 // Save glibc and pthread version strings. Note that _CS_GNU_LIBC_VERSION
545 // and _CS_GNU_LIBPTHREAD_VERSION are supported in glibc >= 2.3.2. Use a
546 // generic name for earlier versions.
547 // Define macros here so we can build HotSpot on old systems.
548 #ifndef _CS_GNU_LIBC_VERSION
549 #define _CS_GNU_LIBC_VERSION 2
550 #endif
551 #ifndef _CS_GNU_LIBPTHREAD_VERSION
552 #define _CS_GNU_LIBPTHREAD_VERSION 3
553 #endif
554
555 size_t n = confstr(_CS_GNU_LIBC_VERSION, NULL, 0);
556 if (n > 0) {
557 char *str = (char *)malloc(n, mtInternal);
558 confstr(_CS_GNU_LIBC_VERSION, str, n);
559 os::Linux::set_glibc_version(str);
560 } else {
561 // _CS_GNU_LIBC_VERSION is not supported, try gnu_get_libc_version()
562 static char _gnu_libc_version[32];
563 jio_snprintf(_gnu_libc_version, sizeof(_gnu_libc_version),
564 "glibc %s %s", gnu_get_libc_version(), gnu_get_libc_release());
565 os::Linux::set_glibc_version(_gnu_libc_version);
566 }
567
568 n = confstr(_CS_GNU_LIBPTHREAD_VERSION, NULL, 0);
569 if (n > 0) {
570 char *str = (char *)malloc(n, mtInternal);
571 confstr(_CS_GNU_LIBPTHREAD_VERSION, str, n);
572 // Vanilla RH-9 (glibc 2.3.2) has a bug that confstr() always tells
573 // us "NPTL-0.29" even we are running with LinuxThreads. Check if this
574 // is the case. LinuxThreads has a hard limit on max number of threads.
575 // So sysconf(_SC_THREAD_THREADS_MAX) will return a positive value.
576 // On the other hand, NPTL does not have such a limit, sysconf()
577 // will return -1 and errno is not changed. Check if it is really NPTL.
578 if (strcmp(os::Linux::glibc_version(), "glibc 2.3.2") == 0 &&
579 strstr(str, "NPTL") &&
580 sysconf(_SC_THREAD_THREADS_MAX) > 0) {
581 free(str);
582 os::Linux::set_libpthread_version("linuxthreads");
583 } else {
584 os::Linux::set_libpthread_version(str);
585 }
586 } else {
587 // glibc before 2.3.2 only has LinuxThreads.
588 os::Linux::set_libpthread_version("linuxthreads");
589 }
590
591 if (strstr(libpthread_version(), "NPTL")) {
592 os::Linux::set_is_NPTL();
593 } else {
594 os::Linux::set_is_LinuxThreads();
595 }
596
597 // LinuxThreads have two flavors: floating-stack mode, which allows variable
598 // stack size; and fixed-stack mode. NPTL is always floating-stack.
599 if (os::Linux::is_NPTL() || os::Linux::supports_variable_stack_size()) {
600 os::Linux::set_is_floating_stack();
601 }
602 }
603
604 /////////////////////////////////////////////////////////////////////////////
605 // thread stack
606
607 // Force Linux kernel to expand current thread stack. If "bottom" is close
608 // to the stack guard, caller should block all signals.
609 //
610 // MAP_GROWSDOWN:
611 // A special mmap() flag that is used to implement thread stacks. It tells
612 // kernel that the memory region should extend downwards when needed. This
613 // allows early versions of LinuxThreads to only mmap the first few pages
614 // when creating a new thread. Linux kernel will automatically expand thread
615 // stack as needed (on page faults).
616 //
617 // However, because the memory region of a MAP_GROWSDOWN stack can grow on
618 // demand, if a page fault happens outside an already mapped MAP_GROWSDOWN
619 // region, it's hard to tell if the fault is due to a legitimate stack
620 // access or because of reading/writing non-exist memory (e.g. buffer
621 // overrun). As a rule, if the fault happens below current stack pointer,
622 // Linux kernel does not expand stack, instead a SIGSEGV is sent to the
623 // application (see Linux kernel fault.c).
624 //
625 // This Linux feature can cause SIGSEGV when VM bangs thread stack for
626 // stack overflow detection.
627 //
628 // Newer version of LinuxThreads (since glibc-2.2, or, RH-7.x) and NPTL do
629 // not use this flag. However, the stack of initial thread is not created
630 // by pthread, it is still MAP_GROWSDOWN. Also it's possible (though
631 // unlikely) that user code can create a thread with MAP_GROWSDOWN stack
632 // and then attach the thread to JVM.
633 //
634 // To get around the problem and allow stack banging on Linux, we need to
635 // manually expand thread stack after receiving the SIGSEGV.
636 //
637 // There are two ways to expand thread stack to address "bottom", we used
638 // both of them in JVM before 1.5:
639 // 1. adjust stack pointer first so that it is below "bottom", and then
640 // touch "bottom"
641 // 2. mmap() the page in question
642 //
643 // Now alternate signal stack is gone, it's harder to use 2. For instance,
644 // if current sp is already near the lower end of page 101, and we need to
645 // call mmap() to map page 100, it is possible that part of the mmap() frame
646 // will be placed in page 100. When page 100 is mapped, it is zero-filled.
647 // That will destroy the mmap() frame and cause VM to crash.
648 //
649 // The following code works by adjusting sp first, then accessing the "bottom"
650 // page to force a page fault. Linux kernel will then automatically expand the
651 // stack mapping.
652 //
653 // _expand_stack_to() assumes its frame size is less than page size, which
654 // should always be true if the function is not inlined.
655
656 #if __GNUC__ < 3 // gcc 2.x does not support noinline attribute
657 #define NOINLINE
658 #else
659 #define NOINLINE __attribute__ ((noinline))
660 #endif
661
662 static void _expand_stack_to(address bottom) NOINLINE;
663
664 static void _expand_stack_to(address bottom) {
665 address sp;
666 size_t size;
667 volatile char *p;
668
669 // Adjust bottom to point to the largest address within the same page, it
670 // gives us a one-page buffer if alloca() allocates slightly more memory.
671 bottom = (address)align_size_down((uintptr_t)bottom, os::Linux::page_size());
672 bottom += os::Linux::page_size() - 1;
673
674 // sp might be slightly above current stack pointer; if that's the case, we
675 // will alloca() a little more space than necessary, which is OK. Don't use
676 // os::current_stack_pointer(), as its result can be slightly below current
677 // stack pointer, causing us to not alloca enough to reach "bottom".
678 sp = (address)&sp;
679
680 if (sp > bottom) {
681 size = sp - bottom;
682 p = (volatile char *)alloca(size);
683 assert(p != NULL && p <= (volatile char *)bottom, "alloca problem?");
684 p[0] = '\0';
685 }
686 }
687
688 bool os::Linux::manually_expand_stack(JavaThread * t, address addr) {
689 assert(t!=NULL, "just checking");
690 assert(t->osthread()->expanding_stack(), "expand should be set");
691 assert(t->stack_base() != NULL, "stack_base was not initialized");
692
693 if (addr < t->stack_base() && addr >= t->stack_yellow_zone_base()) {
694 sigset_t mask_all, old_sigset;
695 sigfillset(&mask_all);
696 pthread_sigmask(SIG_SETMASK, &mask_all, &old_sigset);
697 _expand_stack_to(addr);
698 pthread_sigmask(SIG_SETMASK, &old_sigset, NULL);
699 return true;
700 }
701 return false;
702 }
703
704 //////////////////////////////////////////////////////////////////////////////
705 // create new thread
706
707 static address highest_vm_reserved_address();
708
709 // check if it's safe to start a new thread
710 static bool _thread_safety_check(Thread* thread) {
711 if (os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack()) {
712 // Fixed stack LinuxThreads (SuSE Linux/x86, and some versions of Redhat)
713 // Heap is mmap'ed at lower end of memory space. Thread stacks are
714 // allocated (MAP_FIXED) from high address space. Every thread stack
715 // occupies a fixed size slot (usually 2Mbytes, but user can change
716 // it to other values if they rebuild LinuxThreads).
717 //
718 // Problem with MAP_FIXED is that mmap() can still succeed even part of
719 // the memory region has already been mmap'ed. That means if we have too
720 // many threads and/or very large heap, eventually thread stack will
721 // collide with heap.
722 //
723 // Here we try to prevent heap/stack collision by comparing current
724 // stack bottom with the highest address that has been mmap'ed by JVM
725 // plus a safety margin for memory maps created by native code.
726 //
727 // This feature can be disabled by setting ThreadSafetyMargin to 0
728 //
729 if (ThreadSafetyMargin > 0) {
730 address stack_bottom = os::current_stack_base() - os::current_stack_size();
731
732 // not safe if our stack extends below the safety margin
733 return stack_bottom - ThreadSafetyMargin >= highest_vm_reserved_address();
734 } else {
735 return true;
736 }
737 } else {
738 // Floating stack LinuxThreads or NPTL:
739 // Unlike fixed stack LinuxThreads, thread stacks are not MAP_FIXED. When
740 // there's not enough space left, pthread_create() will fail. If we come
741 // here, that means enough space has been reserved for stack.
742 return true;
743 }
744 }
745
746 // Thread start routine for all newly created threads
747 static void *java_start(Thread *thread) {
748 // Try to randomize the cache line index of hot stack frames.
749 // This helps when threads of the same stack traces evict each other's
750 // cache lines. The threads can be either from the same JVM instance, or
751 // from different JVM instances. The benefit is especially true for
752 // processors with hyperthreading technology.
753 static int counter = 0;
754 int pid = os::current_process_id();
755 alloca(((pid ^ counter++) & 7) * 128);
756
757 ThreadLocalStorage::set_thread(thread);
758
759 OSThread* osthread = thread->osthread();
760 Monitor* sync = osthread->startThread_lock();
761
762 // non floating stack LinuxThreads needs extra check, see above
763 if (!_thread_safety_check(thread)) {
764 // notify parent thread
765 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
766 osthread->set_state(ZOMBIE);
767 sync->notify_all();
768 return NULL;
769 }
770
771 // thread_id is kernel thread id (similar to Solaris LWP id)
772 osthread->set_thread_id(os::Linux::gettid());
773
774 if (UseNUMA) {
775 int lgrp_id = os::numa_get_group_id();
776 if (lgrp_id != -1) {
777 thread->set_lgrp_id(lgrp_id);
778 }
779 }
780 // initialize signal mask for this thread
781 os::Linux::hotspot_sigmask(thread);
782
783 // initialize floating point control register
784 os::Linux::init_thread_fpu_state();
785
786 // handshaking with parent thread
787 {
788 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
789
790 // notify parent thread
791 osthread->set_state(INITIALIZED);
792 sync->notify_all();
793
794 // wait until os::start_thread()
795 while (osthread->get_state() == INITIALIZED) {
796 sync->wait(Mutex::_no_safepoint_check_flag);
797 }
798 }
799
800 // call one more level start routine
801 thread->run();
802
803 return 0;
804 }
805
806 bool os::create_thread(Thread* thread, ThreadType thr_type,
807 size_t stack_size) {
808 assert(thread->osthread() == NULL, "caller responsible");
809
810 // Allocate the OSThread object
811 OSThread* osthread = new OSThread(NULL, NULL);
812 if (osthread == NULL) {
813 return false;
814 }
815
816 // set the correct thread state
817 osthread->set_thread_type(thr_type);
818
819 // Initial state is ALLOCATED but not INITIALIZED
820 osthread->set_state(ALLOCATED);
821
822 thread->set_osthread(osthread);
823
824 // init thread attributes
825 pthread_attr_t attr;
826 pthread_attr_init(&attr);
827 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
828
829 // stack size
830 if (os::Linux::supports_variable_stack_size()) {
831 // calculate stack size if it's not specified by caller
832 if (stack_size == 0) {
833 stack_size = os::Linux::default_stack_size(thr_type);
834
835 switch (thr_type) {
836 case os::java_thread:
837 // Java threads use ThreadStackSize which default value can be
838 // changed with the flag -Xss
839 assert(JavaThread::stack_size_at_create() > 0, "this should be set");
840 stack_size = JavaThread::stack_size_at_create();
841 break;
842 case os::compiler_thread:
843 if (CompilerThreadStackSize > 0) {
844 stack_size = (size_t)(CompilerThreadStackSize * K);
845 break;
846 } // else fall through:
847 // use VMThreadStackSize if CompilerThreadStackSize is not defined
848 case os::vm_thread:
849 case os::pgc_thread:
850 case os::cgc_thread:
851 case os::watcher_thread:
852 if (VMThreadStackSize > 0) stack_size = (size_t)(VMThreadStackSize * K);
853 break;
854 }
855 }
856
857 stack_size = MAX2(stack_size, os::Linux::min_stack_allowed);
858 pthread_attr_setstacksize(&attr, stack_size);
859 } else {
860 // let pthread_create() pick the default value.
861 }
862
863 // glibc guard page
864 pthread_attr_setguardsize(&attr, os::Linux::default_guard_size(thr_type));
865
866 ThreadState state;
867
868 {
869 // Serialize thread creation if we are running with fixed stack LinuxThreads
870 bool lock = os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack();
871 if (lock) {
872 os::Linux::createThread_lock()->lock_without_safepoint_check();
873 }
874
875 pthread_t tid;
876 int ret = pthread_create(&tid, &attr, (void* (*)(void*)) java_start, thread);
877
878 pthread_attr_destroy(&attr);
879
880 if (ret != 0) {
881 if (PrintMiscellaneous && (Verbose || WizardMode)) {
882 perror("pthread_create()");
883 }
884 // Need to clean up stuff we've allocated so far
885 thread->set_osthread(NULL);
886 delete osthread;
887 if (lock) os::Linux::createThread_lock()->unlock();
888 return false;
889 }
890
891 // Store pthread info into the OSThread
892 osthread->set_pthread_id(tid);
893
894 // Wait until child thread is either initialized or aborted
895 {
896 Monitor* sync_with_child = osthread->startThread_lock();
897 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
898 while ((state = osthread->get_state()) == ALLOCATED) {
899 sync_with_child->wait(Mutex::_no_safepoint_check_flag);
900 }
901 }
902
903 if (lock) {
904 os::Linux::createThread_lock()->unlock();
905 }
906 }
907
908 // Aborted due to thread limit being reached
909 if (state == ZOMBIE) {
910 thread->set_osthread(NULL);
911 delete osthread;
912 return false;
913 }
914
915 // The thread is returned suspended (in state INITIALIZED),
916 // and is started higher up in the call chain
917 assert(state == INITIALIZED, "race condition");
918 return true;
919 }
920
921 /////////////////////////////////////////////////////////////////////////////
922 // attach existing thread
923
924 // bootstrap the main thread
925 bool os::create_main_thread(JavaThread* thread) {
926 assert(os::Linux::_main_thread == pthread_self(), "should be called inside main thread");
927 return create_attached_thread(thread);
928 }
929
930 bool os::create_attached_thread(JavaThread* thread) {
931 #ifdef ASSERT
932 thread->verify_not_published();
933 #endif
934
935 // Allocate the OSThread object
936 OSThread* osthread = new OSThread(NULL, NULL);
937
938 if (osthread == NULL) {
939 return false;
940 }
941
942 // Store pthread info into the OSThread
943 osthread->set_thread_id(os::Linux::gettid());
944 osthread->set_pthread_id(::pthread_self());
945
946 // initialize floating point control register
947 os::Linux::init_thread_fpu_state();
948
949 // Initial thread state is RUNNABLE
950 osthread->set_state(RUNNABLE);
951
952 thread->set_osthread(osthread);
953
954 if (UseNUMA) {
955 int lgrp_id = os::numa_get_group_id();
956 if (lgrp_id != -1) {
957 thread->set_lgrp_id(lgrp_id);
958 }
959 }
960
961 if (os::Linux::is_initial_thread()) {
962 // If current thread is initial thread, its stack is mapped on demand,
963 // see notes about MAP_GROWSDOWN. Here we try to force kernel to map
964 // the entire stack region to avoid SEGV in stack banging.
965 // It is also useful to get around the heap-stack-gap problem on SuSE
966 // kernel (see 4821821 for details). We first expand stack to the top
967 // of yellow zone, then enable stack yellow zone (order is significant,
968 // enabling yellow zone first will crash JVM on SuSE Linux), so there
969 // is no gap between the last two virtual memory regions.
970
971 JavaThread *jt = (JavaThread *)thread;
972 address addr = jt->stack_yellow_zone_base();
973 assert(addr != NULL, "initialization problem?");
974 assert(jt->stack_available(addr) > 0, "stack guard should not be enabled");
975
976 osthread->set_expanding_stack();
977 os::Linux::manually_expand_stack(jt, addr);
978 osthread->clear_expanding_stack();
979 }
980
981 // initialize signal mask for this thread
982 // and save the caller's signal mask
983 os::Linux::hotspot_sigmask(thread);
984
985 return true;
986 }
987
988 void os::pd_start_thread(Thread* thread) {
989 OSThread * osthread = thread->osthread();
990 assert(osthread->get_state() != INITIALIZED, "just checking");
991 Monitor* sync_with_child = osthread->startThread_lock();
992 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
993 sync_with_child->notify();
994 }
995
996 // Free Linux resources related to the OSThread
997 void os::free_thread(OSThread* osthread) {
998 assert(osthread != NULL, "osthread not set");
999
1000 if (Thread::current()->osthread() == osthread) {
1001 // Restore caller's signal mask
1002 sigset_t sigmask = osthread->caller_sigmask();
1003 pthread_sigmask(SIG_SETMASK, &sigmask, NULL);
1004 }
1005
1006 delete osthread;
1007 }
1008
1009 //////////////////////////////////////////////////////////////////////////////
1010 // thread local storage
1011
1012 // Restore the thread pointer if the destructor is called. This is in case
1013 // someone from JNI code sets up a destructor with pthread_key_create to run
1014 // detachCurrentThread on thread death. Unless we restore the thread pointer we
1015 // will hang or crash. When detachCurrentThread is called the key will be set
1016 // to null and we will not be called again. If detachCurrentThread is never
1017 // called we could loop forever depending on the pthread implementation.
1018 static void restore_thread_pointer(void* p) {
1019 Thread* thread = (Thread*) p;
1020 os::thread_local_storage_at_put(ThreadLocalStorage::thread_index(), thread);
1021 }
1022
1023 int os::allocate_thread_local_storage() {
1024 pthread_key_t key;
1025 int rslt = pthread_key_create(&key, restore_thread_pointer);
1026 assert(rslt == 0, "cannot allocate thread local storage");
1027 return (int)key;
1028 }
1029
1030 // Note: This is currently not used by VM, as we don't destroy TLS key
1031 // on VM exit.
1032 void os::free_thread_local_storage(int index) {
1033 int rslt = pthread_key_delete((pthread_key_t)index);
1034 assert(rslt == 0, "invalid index");
1035 }
1036
1037 void os::thread_local_storage_at_put(int index, void* value) {
1038 int rslt = pthread_setspecific((pthread_key_t)index, value);
1039 assert(rslt == 0, "pthread_setspecific failed");
1040 }
1041
1042 extern "C" Thread* get_thread() {
1043 return ThreadLocalStorage::thread();
1044 }
1045
1046 //////////////////////////////////////////////////////////////////////////////
1047 // initial thread
1048
1049 // Check if current thread is the initial thread, similar to Solaris thr_main.
1050 bool os::Linux::is_initial_thread(void) {
1051 char dummy;
1052 // If called before init complete, thread stack bottom will be null.
1053 // Can be called if fatal error occurs before initialization.
1054 if (initial_thread_stack_bottom() == NULL) return false;
1055 assert(initial_thread_stack_bottom() != NULL &&
1056 initial_thread_stack_size() != 0,
1057 "os::init did not locate initial thread's stack region");
1058 if ((address)&dummy >= initial_thread_stack_bottom() &&
1059 (address)&dummy < initial_thread_stack_bottom() + initial_thread_stack_size()) {
1060 return true;
1061 } else {
1062 return false;
1063 }
1064 }
1065
1066 // Find the virtual memory area that contains addr
1067 static bool find_vma(address addr, address* vma_low, address* vma_high) {
1068 FILE *fp = fopen("/proc/self/maps", "r");
1069 if (fp) {
1070 address low, high;
1071 while (!feof(fp)) {
1072 if (fscanf(fp, "%p-%p", &low, &high) == 2) {
1073 if (low <= addr && addr < high) {
1074 if (vma_low) *vma_low = low;
1075 if (vma_high) *vma_high = high;
1076 fclose(fp);
1077 return true;
1078 }
1079 }
1080 for (;;) {
1081 int ch = fgetc(fp);
1082 if (ch == EOF || ch == (int)'\n') break;
1083 }
1084 }
1085 fclose(fp);
1086 }
1087 return false;
1088 }
1089
1090 // Locate initial thread stack. This special handling of initial thread stack
1091 // is needed because pthread_getattr_np() on most (all?) Linux distros returns
1092 // bogus value for initial thread.
1093 void os::Linux::capture_initial_stack(size_t max_size) {
1094 // stack size is the easy part, get it from RLIMIT_STACK
1095 size_t stack_size;
1096 struct rlimit rlim;
1097 getrlimit(RLIMIT_STACK, &rlim);
1098 stack_size = rlim.rlim_cur;
1099
1100 // 6308388: a bug in ld.so will relocate its own .data section to the
1101 // lower end of primordial stack; reduce ulimit -s value a little bit
1102 // so we won't install guard page on ld.so's data section.
1103 stack_size -= 2 * page_size();
1104
1105 // 4441425: avoid crash with "unlimited" stack size on SuSE 7.1 or Redhat
1106 // 7.1, in both cases we will get 2G in return value.
1107 // 4466587: glibc 2.2.x compiled w/o "--enable-kernel=2.4.0" (RH 7.0,
1108 // SuSE 7.2, Debian) can not handle alternate signal stack correctly
1109 // for initial thread if its stack size exceeds 6M. Cap it at 2M,
1110 // in case other parts in glibc still assumes 2M max stack size.
1111 // FIXME: alt signal stack is gone, maybe we can relax this constraint?
1112 // Problem still exists RH7.2 (IA64 anyway) but 2MB is a little small
1113 if (stack_size > 2 * K * K IA64_ONLY(*2)) {
1114 stack_size = 2 * K * K IA64_ONLY(*2);
1115 }
1116 // Try to figure out where the stack base (top) is. This is harder.
1117 //
1118 // When an application is started, glibc saves the initial stack pointer in
1119 // a global variable "__libc_stack_end", which is then used by system
1120 // libraries. __libc_stack_end should be pretty close to stack top. The
1121 // variable is available since the very early days. However, because it is
1122 // a private interface, it could disappear in the future.
1123 //
1124 // Linux kernel saves start_stack information in /proc/<pid>/stat. Similar
1125 // to __libc_stack_end, it is very close to stack top, but isn't the real
1126 // stack top. Note that /proc may not exist if VM is running as a chroot
1127 // program, so reading /proc/<pid>/stat could fail. Also the contents of
1128 // /proc/<pid>/stat could change in the future (though unlikely).
1129 //
1130 // We try __libc_stack_end first. If that doesn't work, look for
1131 // /proc/<pid>/stat. If neither of them works, we use current stack pointer
1132 // as a hint, which should work well in most cases.
1133
1134 uintptr_t stack_start;
1135
1136 // try __libc_stack_end first
1137 uintptr_t *p = (uintptr_t *)dlsym(RTLD_DEFAULT, "__libc_stack_end");
1138 if (p && *p) {
1139 stack_start = *p;
1140 } else {
1141 // see if we can get the start_stack field from /proc/self/stat
1142 FILE *fp;
1143 int pid;
1144 char state;
1145 int ppid;
1146 int pgrp;
1147 int session;
1148 int nr;
1149 int tpgrp;
1150 unsigned long flags;
1151 unsigned long minflt;
1152 unsigned long cminflt;
1153 unsigned long majflt;
1154 unsigned long cmajflt;
1155 unsigned long utime;
1156 unsigned long stime;
1157 long cutime;
1158 long cstime;
1159 long prio;
1160 long nice;
1161 long junk;
1162 long it_real;
1163 uintptr_t start;
1164 uintptr_t vsize;
1165 intptr_t rss;
1166 uintptr_t rsslim;
1167 uintptr_t scodes;
1168 uintptr_t ecode;
1169 int i;
1170
1171 // Figure what the primordial thread stack base is. Code is inspired
1172 // by email from Hans Boehm. /proc/self/stat begins with current pid,
1173 // followed by command name surrounded by parentheses, state, etc.
1174 char stat[2048];
1175 int statlen;
1176
1177 fp = fopen("/proc/self/stat", "r");
1178 if (fp) {
1179 statlen = fread(stat, 1, 2047, fp);
1180 stat[statlen] = '\0';
1181 fclose(fp);
1182
1183 // Skip pid and the command string. Note that we could be dealing with
1184 // weird command names, e.g. user could decide to rename java launcher
1185 // to "java 1.4.2 :)", then the stat file would look like
1186 // 1234 (java 1.4.2 :)) R ... ...
1187 // We don't really need to know the command string, just find the last
1188 // occurrence of ")" and then start parsing from there. See bug 4726580.
1189 char * s = strrchr(stat, ')');
1190
1191 i = 0;
1192 if (s) {
1193 // Skip blank chars
1194 do { s++; } while (s && isspace(*s));
1195
1196 #define _UFM UINTX_FORMAT
1197 #define _DFM INTX_FORMAT
1198
1199 // 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2
1200 // 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
1201 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,
1202 &state, // 3 %c
1203 &ppid, // 4 %d
1204 &pgrp, // 5 %d
1205 &session, // 6 %d
1206 &nr, // 7 %d
1207 &tpgrp, // 8 %d
1208 &flags, // 9 %lu
1209 &minflt, // 10 %lu
1210 &cminflt, // 11 %lu
1211 &majflt, // 12 %lu
1212 &cmajflt, // 13 %lu
1213 &utime, // 14 %lu
1214 &stime, // 15 %lu
1215 &cutime, // 16 %ld
1216 &cstime, // 17 %ld
1217 &prio, // 18 %ld
1218 &nice, // 19 %ld
1219 &junk, // 20 %ld
1220 &it_real, // 21 %ld
1221 &start, // 22 UINTX_FORMAT
1222 &vsize, // 23 UINTX_FORMAT
1223 &rss, // 24 INTX_FORMAT
1224 &rsslim, // 25 UINTX_FORMAT
1225 &scodes, // 26 UINTX_FORMAT
1226 &ecode, // 27 UINTX_FORMAT
1227 &stack_start); // 28 UINTX_FORMAT
1228 }
1229
1230 #undef _UFM
1231 #undef _DFM
1232
1233 if (i != 28 - 2) {
1234 assert(false, "Bad conversion from /proc/self/stat");
1235 // product mode - assume we are the initial thread, good luck in the
1236 // embedded case.
1237 warning("Can't detect initial thread stack location - bad conversion");
1238 stack_start = (uintptr_t) &rlim;
1239 }
1240 } else {
1241 // For some reason we can't open /proc/self/stat (for example, running on
1242 // FreeBSD with a Linux emulator, or inside chroot), this should work for
1243 // most cases, so don't abort:
1244 warning("Can't detect initial thread stack location - no /proc/self/stat");
1245 stack_start = (uintptr_t) &rlim;
1246 }
1247 }
1248
1249 // Now we have a pointer (stack_start) very close to the stack top, the
1250 // next thing to do is to figure out the exact location of stack top. We
1251 // can find out the virtual memory area that contains stack_start by
1252 // reading /proc/self/maps, it should be the last vma in /proc/self/maps,
1253 // and its upper limit is the real stack top. (again, this would fail if
1254 // running inside chroot, because /proc may not exist.)
1255
1256 uintptr_t stack_top;
1257 address low, high;
1258 if (find_vma((address)stack_start, &low, &high)) {
1259 // success, "high" is the true stack top. (ignore "low", because initial
1260 // thread stack grows on demand, its real bottom is high - RLIMIT_STACK.)
1261 stack_top = (uintptr_t)high;
1262 } else {
1263 // failed, likely because /proc/self/maps does not exist
1264 warning("Can't detect initial thread stack location - find_vma failed");
1265 // best effort: stack_start is normally within a few pages below the real
1266 // stack top, use it as stack top, and reduce stack size so we won't put
1267 // guard page outside stack.
1268 stack_top = stack_start;
1269 stack_size -= 16 * page_size();
1270 }
1271
1272 // stack_top could be partially down the page so align it
1273 stack_top = align_size_up(stack_top, page_size());
1274
1275 if (max_size && stack_size > max_size) {
1276 _initial_thread_stack_size = max_size;
1277 } else {
1278 _initial_thread_stack_size = stack_size;
1279 }
1280
1281 _initial_thread_stack_size = align_size_down(_initial_thread_stack_size, page_size());
1282 _initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size;
1283 }
1284
1285 ////////////////////////////////////////////////////////////////////////////////
1286 // time support
1287
1288 // Time since start-up in seconds to a fine granularity.
1289 // Used by VMSelfDestructTimer and the MemProfiler.
1290 double os::elapsedTime() {
1291
1292 return ((double)os::elapsed_counter()) / os::elapsed_frequency(); // nanosecond resolution
1293 }
1294
1295 jlong os::elapsed_counter() {
1296 return javaTimeNanos() - initial_time_count;
1297 }
1298
1299 jlong os::elapsed_frequency() {
1300 return NANOSECS_PER_SEC; // nanosecond resolution
1301 }
1302
1303 bool os::supports_vtime() { return true; }
1304 bool os::enable_vtime() { return false; }
1305 bool os::vtime_enabled() { return false; }
1306
1307 double os::elapsedVTime() {
1308 struct rusage usage;
1309 int retval = getrusage(RUSAGE_THREAD, &usage);
1310 if (retval == 0) {
1311 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);
1312 } else {
1313 // better than nothing, but not much
1314 return elapsedTime();
1315 }
1316 }
1317
1318 jlong os::javaTimeMillis() {
1319 timeval time;
1320 int status = gettimeofday(&time, NULL);
1321 assert(status != -1, "linux error");
1322 return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000);
1323 }
1324
1325 void os::javaTimeSystemUTC(jlong &seconds, jlong &nanos) {
1326 timeval time;
1327 int status = gettimeofday(&time, NULL);
1328 assert(status != -1, "linux error");
1329 seconds = jlong(time.tv_sec);
1330 nanos = jlong(time.tv_usec) * 1000;
1331 }
1332
1333
1334 #ifndef CLOCK_MONOTONIC
1335 #define CLOCK_MONOTONIC (1)
1336 #endif
1337
1338 void os::Linux::clock_init() {
1339 // we do dlopen's in this particular order due to bug in linux
1340 // dynamical loader (see 6348968) leading to crash on exit
1341 void* handle = dlopen("librt.so.1", RTLD_LAZY);
1342 if (handle == NULL) {
1343 handle = dlopen("librt.so", RTLD_LAZY);
1344 }
1345
1346 if (handle) {
1347 int (*clock_getres_func)(clockid_t, struct timespec*) =
1348 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres");
1349 int (*clock_gettime_func)(clockid_t, struct timespec*) =
1350 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime");
1351 if (clock_getres_func && clock_gettime_func) {
1352 // See if monotonic clock is supported by the kernel. Note that some
1353 // early implementations simply return kernel jiffies (updated every
1354 // 1/100 or 1/1000 second). It would be bad to use such a low res clock
1355 // for nano time (though the monotonic property is still nice to have).
1356 // It's fixed in newer kernels, however clock_getres() still returns
1357 // 1/HZ. We check if clock_getres() works, but will ignore its reported
1358 // resolution for now. Hopefully as people move to new kernels, this
1359 // won't be a problem.
1360 struct timespec res;
1361 struct timespec tp;
1362 if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 &&
1363 clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) {
1364 // yes, monotonic clock is supported
1365 _clock_gettime = clock_gettime_func;
1366 return;
1367 } else {
1368 // close librt if there is no monotonic clock
1369 dlclose(handle);
1370 }
1371 }
1372 }
1373 warning("No monotonic clock was available - timed services may " \
1374 "be adversely affected if the time-of-day clock changes");
1375 }
1376
1377 #ifndef SYS_clock_getres
1378 #if defined(IA32) || defined(AMD64)
1379 #define SYS_clock_getres IA32_ONLY(266) AMD64_ONLY(229)
1380 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y)
1381 #else
1382 #warning "SYS_clock_getres not defined for this platform, disabling fast_thread_cpu_time"
1383 #define sys_clock_getres(x,y) -1
1384 #endif
1385 #else
1386 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y)
1387 #endif
1388
1389 void os::Linux::fast_thread_clock_init() {
1390 if (!UseLinuxPosixThreadCPUClocks) {
1391 return;
1392 }
1393 clockid_t clockid;
1394 struct timespec tp;
1395 int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) =
1396 (int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid");
1397
1398 // Switch to using fast clocks for thread cpu time if
1399 // the sys_clock_getres() returns 0 error code.
1400 // Note, that some kernels may support the current thread
1401 // clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks
1402 // returned by the pthread_getcpuclockid().
1403 // If the fast Posix clocks are supported then the sys_clock_getres()
1404 // must return at least tp.tv_sec == 0 which means a resolution
1405 // better than 1 sec. This is extra check for reliability.
1406
1407 if (pthread_getcpuclockid_func &&
1408 pthread_getcpuclockid_func(_main_thread, &clockid) == 0 &&
1409 sys_clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) {
1410 _supports_fast_thread_cpu_time = true;
1411 _pthread_getcpuclockid = pthread_getcpuclockid_func;
1412 }
1413 }
1414
1415 jlong os::javaTimeNanos() {
1416 if (os::supports_monotonic_clock()) {
1417 struct timespec tp;
1418 int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp);
1419 assert(status == 0, "gettime error");
1420 jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec);
1421 return result;
1422 } else {
1423 timeval time;
1424 int status = gettimeofday(&time, NULL);
1425 assert(status != -1, "linux error");
1426 jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec);
1427 return 1000 * usecs;
1428 }
1429 }
1430
1431 void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) {
1432 if (os::supports_monotonic_clock()) {
1433 info_ptr->max_value = ALL_64_BITS;
1434
1435 // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past
1436 info_ptr->may_skip_backward = false; // not subject to resetting or drifting
1437 info_ptr->may_skip_forward = false; // not subject to resetting or drifting
1438 } else {
1439 // gettimeofday - based on time in seconds since the Epoch thus does not wrap
1440 info_ptr->max_value = ALL_64_BITS;
1441
1442 // gettimeofday is a real time clock so it skips
1443 info_ptr->may_skip_backward = true;
1444 info_ptr->may_skip_forward = true;
1445 }
1446
1447 info_ptr->kind = JVMTI_TIMER_ELAPSED; // elapsed not CPU time
1448 }
1449
1450 // Return the real, user, and system times in seconds from an
1451 // arbitrary fixed point in the past.
1452 bool os::getTimesSecs(double* process_real_time,
1453 double* process_user_time,
1454 double* process_system_time) {
1455 struct tms ticks;
1456 clock_t real_ticks = times(&ticks);
1457
1458 if (real_ticks == (clock_t) (-1)) {
1459 return false;
1460 } else {
1461 double ticks_per_second = (double) clock_tics_per_sec;
1462 *process_user_time = ((double) ticks.tms_utime) / ticks_per_second;
1463 *process_system_time = ((double) ticks.tms_stime) / ticks_per_second;
1464 *process_real_time = ((double) real_ticks) / ticks_per_second;
1465
1466 return true;
1467 }
1468 }
1469
1470
1471 char * os::local_time_string(char *buf, size_t buflen) {
1472 struct tm t;
1473 time_t long_time;
1474 time(&long_time);
1475 localtime_r(&long_time, &t);
1476 jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d",
1477 t.tm_year + 1900, t.tm_mon + 1, t.tm_mday,
1478 t.tm_hour, t.tm_min, t.tm_sec);
1479 return buf;
1480 }
1481
1482 struct tm* os::localtime_pd(const time_t* clock, struct tm* res) {
1483 return localtime_r(clock, res);
1484 }
1485
1486 ////////////////////////////////////////////////////////////////////////////////
1487 // runtime exit support
1488
1489 // Note: os::shutdown() might be called very early during initialization, or
1490 // called from signal handler. Before adding something to os::shutdown(), make
1491 // sure it is async-safe and can handle partially initialized VM.
1492 void os::shutdown() {
1493
1494 // allow PerfMemory to attempt cleanup of any persistent resources
1495 perfMemory_exit();
1496
1497 // needs to remove object in file system
1498 AttachListener::abort();
1499
1500 // flush buffered output, finish log files
1501 ostream_abort();
1502
1503 // Check for abort hook
1504 abort_hook_t abort_hook = Arguments::abort_hook();
1505 if (abort_hook != NULL) {
1506 abort_hook();
1507 }
1508
1509 }
1510
1511 // Note: os::abort() might be called very early during initialization, or
1512 // called from signal handler. Before adding something to os::abort(), make
1513 // sure it is async-safe and can handle partially initialized VM.
1514 void os::abort(bool dump_core) {
1515 os::shutdown();
1516 if (dump_core) {
1517 #ifndef PRODUCT
1518 fdStream out(defaultStream::output_fd());
1519 out.print_raw("Current thread is ");
1520 char buf[16];
1521 jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id());
1522 out.print_raw_cr(buf);
1523 out.print_raw_cr("Dumping core ...");
1524 #endif
1525 ::abort(); // dump core
1526 }
1527
1528 ::exit(1);
1529 }
1530
1531 // Die immediately, no exit hook, no abort hook, no cleanup.
1532 void os::die() {
1533 // _exit() on LinuxThreads only kills current thread
1534 ::abort();
1535 }
1536
1537
1538 // This method is a copy of JDK's sysGetLastErrorString
1539 // from src/solaris/hpi/src/system_md.c
1540
1541 size_t os::lasterror(char *buf, size_t len) {
1542 if (errno == 0) return 0;
1543
1544 const char *s = ::strerror(errno);
1545 size_t n = ::strlen(s);
1546 if (n >= len) {
1547 n = len - 1;
1548 }
1549 ::strncpy(buf, s, n);
1550 buf[n] = '\0';
1551 return n;
1552 }
1553
1554 intx os::current_thread_id() { return (intx)pthread_self(); }
1555 int os::current_process_id() {
1556
1557 // Under the old linux thread library, linux gives each thread
1558 // its own process id. Because of this each thread will return
1559 // a different pid if this method were to return the result
1560 // of getpid(2). Linux provides no api that returns the pid
1561 // of the launcher thread for the vm. This implementation
1562 // returns a unique pid, the pid of the launcher thread
1563 // that starts the vm 'process'.
1564
1565 // Under the NPTL, getpid() returns the same pid as the
1566 // launcher thread rather than a unique pid per thread.
1567 // Use gettid() if you want the old pre NPTL behaviour.
1568
1569 // if you are looking for the result of a call to getpid() that
1570 // returns a unique pid for the calling thread, then look at the
1571 // OSThread::thread_id() method in osThread_linux.hpp file
1572
1573 return (int)(_initial_pid ? _initial_pid : getpid());
1574 }
1575
1576 // DLL functions
1577
1578 const char* os::dll_file_extension() { return ".so"; }
1579
1580 // This must be hard coded because it's the system's temporary
1581 // directory not the java application's temp directory, ala java.io.tmpdir.
1582 const char* os::get_temp_directory() { return "/tmp"; }
1583
1584 static bool file_exists(const char* filename) {
1585 struct stat statbuf;
1586 if (filename == NULL || strlen(filename) == 0) {
1587 return false;
1588 }
1589 return os::stat(filename, &statbuf) == 0;
1590 }
1591
1592 bool os::dll_build_name(char* buffer, size_t buflen,
1593 const char* pname, const char* fname) {
1594 bool retval = false;
1595 // Copied from libhpi
1596 const size_t pnamelen = pname ? strlen(pname) : 0;
1597
1598 // Return error on buffer overflow.
1599 if (pnamelen + strlen(fname) + 10 > (size_t) buflen) {
1600 return retval;
1601 }
1602
1603 if (pnamelen == 0) {
1604 snprintf(buffer, buflen, "lib%s.so", fname);
1605 retval = true;
1606 } else if (strchr(pname, *os::path_separator()) != NULL) {
1607 int n;
1608 char** pelements = split_path(pname, &n);
1609 if (pelements == NULL) {
1610 return false;
1611 }
1612 for (int i = 0; i < n; i++) {
1613 // Really shouldn't be NULL, but check can't hurt
1614 if (pelements[i] == NULL || strlen(pelements[i]) == 0) {
1615 continue; // skip the empty path values
1616 }
1617 snprintf(buffer, buflen, "%s/lib%s.so", pelements[i], fname);
1618 if (file_exists(buffer)) {
1619 retval = true;
1620 break;
1621 }
1622 }
1623 // release the storage
1624 for (int i = 0; i < n; i++) {
1625 if (pelements[i] != NULL) {
1626 FREE_C_HEAP_ARRAY(char, pelements[i]);
1627 }
1628 }
1629 if (pelements != NULL) {
1630 FREE_C_HEAP_ARRAY(char*, pelements);
1631 }
1632 } else {
1633 snprintf(buffer, buflen, "%s/lib%s.so", pname, fname);
1634 retval = true;
1635 }
1636 return retval;
1637 }
1638
1639 // check if addr is inside libjvm.so
1640 bool os::address_is_in_vm(address addr) {
1641 static address libjvm_base_addr;
1642 Dl_info dlinfo;
1643
1644 if (libjvm_base_addr == NULL) {
1645 if (dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo) != 0) {
1646 libjvm_base_addr = (address)dlinfo.dli_fbase;
1647 }
1648 assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm");
1649 }
1650
1651 if (dladdr((void *)addr, &dlinfo) != 0) {
1652 if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true;
1653 }
1654
1655 return false;
1656 }
1657
1658 bool os::dll_address_to_function_name(address addr, char *buf,
1659 int buflen, int *offset) {
1660 // buf is not optional, but offset is optional
1661 assert(buf != NULL, "sanity check");
1662
1663 Dl_info dlinfo;
1664
1665 if (dladdr((void*)addr, &dlinfo) != 0) {
1666 // see if we have a matching symbol
1667 if (dlinfo.dli_saddr != NULL && dlinfo.dli_sname != NULL) {
1668 if (!Decoder::demangle(dlinfo.dli_sname, buf, buflen)) {
1669 jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname);
1670 }
1671 if (offset != NULL) *offset = addr - (address)dlinfo.dli_saddr;
1672 return true;
1673 }
1674 // no matching symbol so try for just file info
1675 if (dlinfo.dli_fname != NULL && dlinfo.dli_fbase != NULL) {
1676 if (Decoder::decode((address)(addr - (address)dlinfo.dli_fbase),
1677 buf, buflen, offset, dlinfo.dli_fname)) {
1678 return true;
1679 }
1680 }
1681 }
1682
1683 buf[0] = '\0';
1684 if (offset != NULL) *offset = -1;
1685 return false;
1686 }
1687
1688 struct _address_to_library_name {
1689 address addr; // input : memory address
1690 size_t buflen; // size of fname
1691 char* fname; // output: library name
1692 address base; // library base addr
1693 };
1694
1695 static int address_to_library_name_callback(struct dl_phdr_info *info,
1696 size_t size, void *data) {
1697 int i;
1698 bool found = false;
1699 address libbase = NULL;
1700 struct _address_to_library_name * d = (struct _address_to_library_name *)data;
1701
1702 // iterate through all loadable segments
1703 for (i = 0; i < info->dlpi_phnum; i++) {
1704 address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr);
1705 if (info->dlpi_phdr[i].p_type == PT_LOAD) {
1706 // base address of a library is the lowest address of its loaded
1707 // segments.
1708 if (libbase == NULL || libbase > segbase) {
1709 libbase = segbase;
1710 }
1711 // see if 'addr' is within current segment
1712 if (segbase <= d->addr &&
1713 d->addr < segbase + info->dlpi_phdr[i].p_memsz) {
1714 found = true;
1715 }
1716 }
1717 }
1718
1719 // dlpi_name is NULL or empty if the ELF file is executable, return 0
1720 // so dll_address_to_library_name() can fall through to use dladdr() which
1721 // can figure out executable name from argv[0].
1722 if (found && info->dlpi_name && info->dlpi_name[0]) {
1723 d->base = libbase;
1724 if (d->fname) {
1725 jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name);
1726 }
1727 return 1;
1728 }
1729 return 0;
1730 }
1731
1732 bool os::dll_address_to_library_name(address addr, char* buf,
1733 int buflen, int* offset) {
1734 // buf is not optional, but offset is optional
1735 assert(buf != NULL, "sanity check");
1736
1737 Dl_info dlinfo;
1738 struct _address_to_library_name data;
1739
1740 // There is a bug in old glibc dladdr() implementation that it could resolve
1741 // to wrong library name if the .so file has a base address != NULL. Here
1742 // we iterate through the program headers of all loaded libraries to find
1743 // out which library 'addr' really belongs to. This workaround can be
1744 // removed once the minimum requirement for glibc is moved to 2.3.x.
1745 data.addr = addr;
1746 data.fname = buf;
1747 data.buflen = buflen;
1748 data.base = NULL;
1749 int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data);
1750
1751 if (rslt) {
1752 // buf already contains library name
1753 if (offset) *offset = addr - data.base;
1754 return true;
1755 }
1756 if (dladdr((void*)addr, &dlinfo) != 0) {
1757 if (dlinfo.dli_fname != NULL) {
1758 jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname);
1759 }
1760 if (dlinfo.dli_fbase != NULL && offset != NULL) {
1761 *offset = addr - (address)dlinfo.dli_fbase;
1762 }
1763 return true;
1764 }
1765
1766 buf[0] = '\0';
1767 if (offset) *offset = -1;
1768 return false;
1769 }
1770
1771 // Loads .dll/.so and
1772 // in case of error it checks if .dll/.so was built for the
1773 // same architecture as Hotspot is running on
1774
1775
1776 // Remember the stack's state. The Linux dynamic linker will change
1777 // the stack to 'executable' at most once, so we must safepoint only once.
1778 bool os::Linux::_stack_is_executable = false;
1779
1780 // VM operation that loads a library. This is necessary if stack protection
1781 // of the Java stacks can be lost during loading the library. If we
1782 // do not stop the Java threads, they can stack overflow before the stacks
1783 // are protected again.
1784 class VM_LinuxDllLoad: public VM_Operation {
1785 private:
1786 const char *_filename;
1787 char *_ebuf;
1788 int _ebuflen;
1789 void *_lib;
1790 public:
1791 VM_LinuxDllLoad(const char *fn, char *ebuf, int ebuflen) :
1792 _filename(fn), _ebuf(ebuf), _ebuflen(ebuflen), _lib(NULL) {}
1793 VMOp_Type type() const { return VMOp_LinuxDllLoad; }
1794 void doit() {
1795 _lib = os::Linux::dll_load_in_vmthread(_filename, _ebuf, _ebuflen);
1796 os::Linux::_stack_is_executable = true;
1797 }
1798 void* loaded_library() { return _lib; }
1799 };
1800
1801 void * os::dll_load(const char *filename, char *ebuf, int ebuflen) {
1802 void * result = NULL;
1803 bool load_attempted = false;
1804
1805 // Check whether the library to load might change execution rights
1806 // of the stack. If they are changed, the protection of the stack
1807 // guard pages will be lost. We need a safepoint to fix this.
1808 //
1809 // See Linux man page execstack(8) for more info.
1810 if (os::uses_stack_guard_pages() && !os::Linux::_stack_is_executable) {
1811 ElfFile ef(filename);
1812 if (!ef.specifies_noexecstack()) {
1813 if (!is_init_completed()) {
1814 os::Linux::_stack_is_executable = true;
1815 // This is OK - No Java threads have been created yet, and hence no
1816 // stack guard pages to fix.
1817 //
1818 // This should happen only when you are building JDK7 using a very
1819 // old version of JDK6 (e.g., with JPRT) and running test_gamma.
1820 //
1821 // Dynamic loader will make all stacks executable after
1822 // this function returns, and will not do that again.
1823 assert(Threads::first() == NULL, "no Java threads should exist yet.");
1824 } else {
1825 warning("You have loaded library %s which might have disabled stack guard. "
1826 "The VM will try to fix the stack guard now.\n"
1827 "It's highly recommended that you fix the library with "
1828 "'execstack -c <libfile>', or link it with '-z noexecstack'.",
1829 filename);
1830
1831 assert(Thread::current()->is_Java_thread(), "must be Java thread");
1832 JavaThread *jt = JavaThread::current();
1833 if (jt->thread_state() != _thread_in_native) {
1834 // This happens when a compiler thread tries to load a hsdis-<arch>.so file
1835 // that requires ExecStack. Cannot enter safe point. Let's give up.
1836 warning("Unable to fix stack guard. Giving up.");
1837 } else {
1838 if (!LoadExecStackDllInVMThread) {
1839 // This is for the case where the DLL has an static
1840 // constructor function that executes JNI code. We cannot
1841 // load such DLLs in the VMThread.
1842 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen);
1843 }
1844
1845 ThreadInVMfromNative tiv(jt);
1846 debug_only(VMNativeEntryWrapper vew;)
1847
1848 VM_LinuxDllLoad op(filename, ebuf, ebuflen);
1849 VMThread::execute(&op);
1850 if (LoadExecStackDllInVMThread) {
1851 result = op.loaded_library();
1852 }
1853 load_attempted = true;
1854 }
1855 }
1856 }
1857 }
1858
1859 if (!load_attempted) {
1860 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen);
1861 }
1862
1863 if (result != NULL) {
1864 // Successful loading
1865 return result;
1866 }
1867
1868 Elf32_Ehdr elf_head;
1869 int diag_msg_max_length=ebuflen-strlen(ebuf);
1870 char* diag_msg_buf=ebuf+strlen(ebuf);
1871
1872 if (diag_msg_max_length==0) {
1873 // No more space in ebuf for additional diagnostics message
1874 return NULL;
1875 }
1876
1877
1878 int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK);
1879
1880 if (file_descriptor < 0) {
1881 // Can't open library, report dlerror() message
1882 return NULL;
1883 }
1884
1885 bool failed_to_read_elf_head=
1886 (sizeof(elf_head)!=
1887 (::read(file_descriptor, &elf_head,sizeof(elf_head))));
1888
1889 ::close(file_descriptor);
1890 if (failed_to_read_elf_head) {
1891 // file i/o error - report dlerror() msg
1892 return NULL;
1893 }
1894
1895 typedef struct {
1896 Elf32_Half code; // Actual value as defined in elf.h
1897 Elf32_Half compat_class; // Compatibility of archs at VM's sense
1898 char elf_class; // 32 or 64 bit
1899 char endianess; // MSB or LSB
1900 char* name; // String representation
1901 } arch_t;
1902
1903 #ifndef EM_486
1904 #define EM_486 6 /* Intel 80486 */
1905 #endif
1906
1907 static const arch_t arch_array[]={
1908 {EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
1909 {EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
1910 {EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"},
1911 {EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"},
1912 {EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
1913 {EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
1914 {EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"},
1915 {EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"},
1916 #if defined(VM_LITTLE_ENDIAN)
1917 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2LSB, (char*)"Power PC 64"},
1918 #else
1919 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"},
1920 #endif
1921 {EM_ARM, EM_ARM, ELFCLASS32, ELFDATA2LSB, (char*)"ARM"},
1922 {EM_S390, EM_S390, ELFCLASSNONE, ELFDATA2MSB, (char*)"IBM System/390"},
1923 {EM_ALPHA, EM_ALPHA, ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"},
1924 {EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"},
1925 {EM_MIPS, EM_MIPS, ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"},
1926 {EM_PARISC, EM_PARISC, ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"},
1927 {EM_68K, EM_68K, ELFCLASS32, ELFDATA2MSB, (char*)"M68k"}
1928 };
1929
1930 #if (defined IA32)
1931 static Elf32_Half running_arch_code=EM_386;
1932 #elif (defined AMD64)
1933 static Elf32_Half running_arch_code=EM_X86_64;
1934 #elif (defined IA64)
1935 static Elf32_Half running_arch_code=EM_IA_64;
1936 #elif (defined __sparc) && (defined _LP64)
1937 static Elf32_Half running_arch_code=EM_SPARCV9;
1938 #elif (defined __sparc) && (!defined _LP64)
1939 static Elf32_Half running_arch_code=EM_SPARC;
1940 #elif (defined __powerpc64__)
1941 static Elf32_Half running_arch_code=EM_PPC64;
1942 #elif (defined __powerpc__)
1943 static Elf32_Half running_arch_code=EM_PPC;
1944 #elif (defined ARM)
1945 static Elf32_Half running_arch_code=EM_ARM;
1946 #elif (defined S390)
1947 static Elf32_Half running_arch_code=EM_S390;
1948 #elif (defined ALPHA)
1949 static Elf32_Half running_arch_code=EM_ALPHA;
1950 #elif (defined MIPSEL)
1951 static Elf32_Half running_arch_code=EM_MIPS_RS3_LE;
1952 #elif (defined PARISC)
1953 static Elf32_Half running_arch_code=EM_PARISC;
1954 #elif (defined MIPS)
1955 static Elf32_Half running_arch_code=EM_MIPS;
1956 #elif (defined M68K)
1957 static Elf32_Half running_arch_code=EM_68K;
1958 #else
1959 #error Method os::dll_load requires that one of following is defined:\
1960 IA32, AMD64, IA64, __sparc, __powerpc__, ARM, S390, ALPHA, MIPS, MIPSEL, PARISC, M68K
1961 #endif
1962
1963 // Identify compatability class for VM's architecture and library's architecture
1964 // Obtain string descriptions for architectures
1965
1966 arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL};
1967 int running_arch_index=-1;
1968
1969 for (unsigned int i=0; i < ARRAY_SIZE(arch_array); i++) {
1970 if (running_arch_code == arch_array[i].code) {
1971 running_arch_index = i;
1972 }
1973 if (lib_arch.code == arch_array[i].code) {
1974 lib_arch.compat_class = arch_array[i].compat_class;
1975 lib_arch.name = arch_array[i].name;
1976 }
1977 }
1978
1979 assert(running_arch_index != -1,
1980 "Didn't find running architecture code (running_arch_code) in arch_array");
1981 if (running_arch_index == -1) {
1982 // Even though running architecture detection failed
1983 // we may still continue with reporting dlerror() message
1984 return NULL;
1985 }
1986
1987 if (lib_arch.endianess != arch_array[running_arch_index].endianess) {
1988 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)");
1989 return NULL;
1990 }
1991
1992 #ifndef S390
1993 if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) {
1994 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)");
1995 return NULL;
1996 }
1997 #endif // !S390
1998
1999 if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) {
2000 if (lib_arch.name!=NULL) {
2001 ::snprintf(diag_msg_buf, diag_msg_max_length-1,
2002 " (Possible cause: can't load %s-bit .so on a %s-bit platform)",
2003 lib_arch.name, arch_array[running_arch_index].name);
2004 } else {
2005 ::snprintf(diag_msg_buf, diag_msg_max_length-1,
2006 " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)",
2007 lib_arch.code,
2008 arch_array[running_arch_index].name);
2009 }
2010 }
2011
2012 return NULL;
2013 }
2014
2015 void * os::Linux::dlopen_helper(const char *filename, char *ebuf,
2016 int ebuflen) {
2017 void * result = ::dlopen(filename, RTLD_LAZY);
2018 if (result == NULL) {
2019 ::strncpy(ebuf, ::dlerror(), ebuflen - 1);
2020 ebuf[ebuflen-1] = '\0';
2021 }
2022 return result;
2023 }
2024
2025 void * os::Linux::dll_load_in_vmthread(const char *filename, char *ebuf,
2026 int ebuflen) {
2027 void * result = NULL;
2028 if (LoadExecStackDllInVMThread) {
2029 result = dlopen_helper(filename, ebuf, ebuflen);
2030 }
2031
2032 // Since 7019808, libjvm.so is linked with -noexecstack. If the VM loads a
2033 // library that requires an executable stack, or which does not have this
2034 // stack attribute set, dlopen changes the stack attribute to executable. The
2035 // read protection of the guard pages gets lost.
2036 //
2037 // Need to check _stack_is_executable again as multiple VM_LinuxDllLoad
2038 // may have been queued at the same time.
2039
2040 if (!_stack_is_executable) {
2041 JavaThread *jt = Threads::first();
2042
2043 while (jt) {
2044 if (!jt->stack_guard_zone_unused() && // Stack not yet fully initialized
2045 jt->stack_yellow_zone_enabled()) { // No pending stack overflow exceptions
2046 if (!os::guard_memory((char *) jt->stack_red_zone_base() - jt->stack_red_zone_size(),
2047 jt->stack_yellow_zone_size() + jt->stack_red_zone_size())) {
2048 warning("Attempt to reguard stack yellow zone failed.");
2049 }
2050 }
2051 jt = jt->next();
2052 }
2053 }
2054
2055 return result;
2056 }
2057
2058 // glibc-2.0 libdl is not MT safe. If you are building with any glibc,
2059 // chances are you might want to run the generated bits against glibc-2.0
2060 // libdl.so, so always use locking for any version of glibc.
2061 //
2062 void* os::dll_lookup(void* handle, const char* name) {
2063 pthread_mutex_lock(&dl_mutex);
2064 void* res = dlsym(handle, name);
2065 pthread_mutex_unlock(&dl_mutex);
2066 return res;
2067 }
2068
2069 void* os::get_default_process_handle() {
2070 return (void*)::dlopen(NULL, RTLD_LAZY);
2071 }
2072
2073 static bool _print_ascii_file(const char* filename, outputStream* st) {
2074 int fd = ::open(filename, O_RDONLY);
2075 if (fd == -1) {
2076 return false;
2077 }
2078
2079 char buf[32];
2080 int bytes;
2081 while ((bytes = ::read(fd, buf, sizeof(buf))) > 0) {
2082 st->print_raw(buf, bytes);
2083 }
2084
2085 ::close(fd);
2086
2087 return true;
2088 }
2089
2090 void os::print_dll_info(outputStream *st) {
2091 st->print_cr("Dynamic libraries:");
2092
2093 char fname[32];
2094 pid_t pid = os::Linux::gettid();
2095
2096 jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid);
2097
2098 if (!_print_ascii_file(fname, st)) {
2099 st->print("Can not get library information for pid = %d\n", pid);
2100 }
2101 }
2102
2103 int os::get_loaded_modules_info(os::LoadedModulesCallbackFunc callback, void *param) {
2104 FILE *procmapsFile = NULL;
2105
2106 // Open the procfs maps file for the current process
2107 if ((procmapsFile = fopen("/proc/self/maps", "r")) != NULL) {
2108 // Allocate PATH_MAX for file name plus a reasonable size for other fields.
2109 char line[PATH_MAX + 100];
2110
2111 // Read line by line from 'file'
2112 while (fgets(line, sizeof(line), procmapsFile) != NULL) {
2113 u8 base, top, offset, inode;
2114 char permissions[5];
2115 char device[6];
2116 char name[PATH_MAX + 1];
2117
2118 // Parse fields from line
2119 sscanf(line, "%lx-%lx %4s %lx %5s %ld %s", &base, &top, permissions, &offset, device, &inode, name);
2120
2121 // Filter by device id '00:00' so that we only get file system mapped files.
2122 if (strcmp(device, "00:00") != 0) {
2123
2124 // Call callback with the fields of interest
2125 if(callback(name, (address)base, (address)top, param)) {
2126 // Oops abort, callback aborted
2127 fclose(procmapsFile);
2128 return 1;
2129 }
2130 }
2131 }
2132 fclose(procmapsFile);
2133 }
2134 return 0;
2135 }
2136
2137 void os::print_os_info_brief(outputStream* st) {
2138 os::Linux::print_distro_info(st);
2139
2140 os::Posix::print_uname_info(st);
2141
2142 os::Linux::print_libversion_info(st);
2143
2144 }
2145
2146 void os::print_os_info(outputStream* st) {
2147 st->print("OS:");
2148
2149 os::Linux::print_distro_info(st);
2150
2151 os::Posix::print_uname_info(st);
2152
2153 // Print warning if unsafe chroot environment detected
2154 if (unsafe_chroot_detected) {
2155 st->print("WARNING!! ");
2156 st->print_cr("%s", unstable_chroot_error);
2157 }
2158
2159 os::Linux::print_libversion_info(st);
2160
2161 os::Posix::print_rlimit_info(st);
2162
2163 os::Posix::print_load_average(st);
2164
2165 os::Linux::print_full_memory_info(st);
2166 }
2167
2168 // Try to identify popular distros.
2169 // Most Linux distributions have a /etc/XXX-release file, which contains
2170 // the OS version string. Newer Linux distributions have a /etc/lsb-release
2171 // file that also contains the OS version string. Some have more than one
2172 // /etc/XXX-release file (e.g. Mandrake has both /etc/mandrake-release and
2173 // /etc/redhat-release.), so the order is important.
2174 // Any Linux that is based on Redhat (i.e. Oracle, Mandrake, Sun JDS...) have
2175 // their own specific XXX-release file as well as a redhat-release file.
2176 // Because of this the XXX-release file needs to be searched for before the
2177 // redhat-release file.
2178 // Since Red Hat has a lsb-release file that is not very descriptive the
2179 // search for redhat-release needs to be before lsb-release.
2180 // Since the lsb-release file is the new standard it needs to be searched
2181 // before the older style release files.
2182 // Searching system-release (Red Hat) and os-release (other Linuxes) are a
2183 // next to last resort. The os-release file is a new standard that contains
2184 // distribution information and the system-release file seems to be an old
2185 // standard that has been replaced by the lsb-release and os-release files.
2186 // Searching for the debian_version file is the last resort. It contains
2187 // an informative string like "6.0.6" or "wheezy/sid". Because of this
2188 // "Debian " is printed before the contents of the debian_version file.
2189 void os::Linux::print_distro_info(outputStream* st) {
2190 if (!_print_ascii_file("/etc/oracle-release", st) &&
2191 !_print_ascii_file("/etc/mandriva-release", st) &&
2192 !_print_ascii_file("/etc/mandrake-release", st) &&
2193 !_print_ascii_file("/etc/sun-release", st) &&
2194 !_print_ascii_file("/etc/redhat-release", st) &&
2195 !_print_ascii_file("/etc/lsb-release", st) &&
2196 !_print_ascii_file("/etc/SuSE-release", st) &&
2197 !_print_ascii_file("/etc/turbolinux-release", st) &&
2198 !_print_ascii_file("/etc/gentoo-release", st) &&
2199 !_print_ascii_file("/etc/ltib-release", st) &&
2200 !_print_ascii_file("/etc/angstrom-version", st) &&
2201 !_print_ascii_file("/etc/system-release", st) &&
2202 !_print_ascii_file("/etc/os-release", st)) {
2203
2204 if (file_exists("/etc/debian_version")) {
2205 st->print("Debian ");
2206 _print_ascii_file("/etc/debian_version", st);
2207 } else {
2208 st->print("Linux");
2209 }
2210 }
2211 st->cr();
2212 }
2213
2214 void os::Linux::print_libversion_info(outputStream* st) {
2215 // libc, pthread
2216 st->print("libc:");
2217 st->print("%s ", os::Linux::glibc_version());
2218 st->print("%s ", os::Linux::libpthread_version());
2219 if (os::Linux::is_LinuxThreads()) {
2220 st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed");
2221 }
2222 st->cr();
2223 }
2224
2225 void os::Linux::print_full_memory_info(outputStream* st) {
2226 st->print("\n/proc/meminfo:\n");
2227 _print_ascii_file("/proc/meminfo", st);
2228 st->cr();
2229 }
2230
2231 void os::print_memory_info(outputStream* st) {
2232
2233 st->print("Memory:");
2234 st->print(" %dk page", os::vm_page_size()>>10);
2235
2236 // values in struct sysinfo are "unsigned long"
2237 struct sysinfo si;
2238 sysinfo(&si);
2239
2240 st->print(", physical " UINT64_FORMAT "k",
2241 os::physical_memory() >> 10);
2242 st->print("(" UINT64_FORMAT "k free)",
2243 os::available_memory() >> 10);
2244 st->print(", swap " UINT64_FORMAT "k",
2245 ((jlong)si.totalswap * si.mem_unit) >> 10);
2246 st->print("(" UINT64_FORMAT "k free)",
2247 ((jlong)si.freeswap * si.mem_unit) >> 10);
2248 st->cr();
2249 }
2250
2251 void os::pd_print_cpu_info(outputStream* st) {
2252 st->print("\n/proc/cpuinfo:\n");
2253 if (!_print_ascii_file("/proc/cpuinfo", st)) {
2254 st->print(" <Not Available>");
2255 }
2256 st->cr();
2257 }
2258
2259 void os::print_siginfo(outputStream* st, void* siginfo) {
2260 const siginfo_t* si = (const siginfo_t*)siginfo;
2261
2262 os::Posix::print_siginfo_brief(st, si);
2263 #if INCLUDE_CDS
2264 if (si && (si->si_signo == SIGBUS || si->si_signo == SIGSEGV) &&
2265 UseSharedSpaces) {
2266 FileMapInfo* mapinfo = FileMapInfo::current_info();
2267 if (mapinfo->is_in_shared_space(si->si_addr)) {
2268 st->print("\n\nError accessing class data sharing archive." \
2269 " Mapped file inaccessible during execution, " \
2270 " possible disk/network problem.");
2271 }
2272 }
2273 #endif
2274 st->cr();
2275 }
2276
2277
2278 static void print_signal_handler(outputStream* st, int sig,
2279 char* buf, size_t buflen);
2280
2281 void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) {
2282 st->print_cr("Signal Handlers:");
2283 print_signal_handler(st, SIGSEGV, buf, buflen);
2284 print_signal_handler(st, SIGBUS , buf, buflen);
2285 print_signal_handler(st, SIGFPE , buf, buflen);
2286 print_signal_handler(st, SIGPIPE, buf, buflen);
2287 print_signal_handler(st, SIGXFSZ, buf, buflen);
2288 print_signal_handler(st, SIGILL , buf, buflen);
2289 print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen);
2290 print_signal_handler(st, SR_signum, buf, buflen);
2291 print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen);
2292 print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen);
2293 print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen);
2294 print_signal_handler(st, BREAK_SIGNAL, buf, buflen);
2295 #if defined(PPC64)
2296 print_signal_handler(st, SIGTRAP, buf, buflen);
2297 #endif
2298 }
2299
2300 static char saved_jvm_path[MAXPATHLEN] = {0};
2301
2302 // Find the full path to the current module, libjvm.so
2303 void os::jvm_path(char *buf, jint buflen) {
2304 // Error checking.
2305 if (buflen < MAXPATHLEN) {
2306 assert(false, "must use a large-enough buffer");
2307 buf[0] = '\0';
2308 return;
2309 }
2310 // Lazy resolve the path to current module.
2311 if (saved_jvm_path[0] != 0) {
2312 strcpy(buf, saved_jvm_path);
2313 return;
2314 }
2315
2316 char dli_fname[MAXPATHLEN];
2317 bool ret = dll_address_to_library_name(
2318 CAST_FROM_FN_PTR(address, os::jvm_path),
2319 dli_fname, sizeof(dli_fname), NULL);
2320 assert(ret, "cannot locate libjvm");
2321 char *rp = NULL;
2322 if (ret && dli_fname[0] != '\0') {
2323 rp = realpath(dli_fname, buf);
2324 }
2325 if (rp == NULL) {
2326 return;
2327 }
2328
2329 if (Arguments::sun_java_launcher_is_altjvm()) {
2330 // Support for the java launcher's '-XXaltjvm=<path>' option. Typical
2331 // value for buf is "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so".
2332 // If "/jre/lib/" appears at the right place in the string, then
2333 // assume we are installed in a JDK and we're done. Otherwise, check
2334 // for a JAVA_HOME environment variable and fix up the path so it
2335 // looks like libjvm.so is installed there (append a fake suffix
2336 // hotspot/libjvm.so).
2337 const char *p = buf + strlen(buf) - 1;
2338 for (int count = 0; p > buf && count < 5; ++count) {
2339 for (--p; p > buf && *p != '/'; --p)
2340 /* empty */ ;
2341 }
2342
2343 if (strncmp(p, "/jre/lib/", 9) != 0) {
2344 // Look for JAVA_HOME in the environment.
2345 char* java_home_var = ::getenv("JAVA_HOME");
2346 if (java_home_var != NULL && java_home_var[0] != 0) {
2347 char* jrelib_p;
2348 int len;
2349
2350 // Check the current module name "libjvm.so".
2351 p = strrchr(buf, '/');
2352 if (p == NULL) {
2353 return;
2354 }
2355 assert(strstr(p, "/libjvm") == p, "invalid library name");
2356
2357 rp = realpath(java_home_var, buf);
2358 if (rp == NULL) {
2359 return;
2360 }
2361
2362 // determine if this is a legacy image or modules image
2363 // modules image doesn't have "jre" subdirectory
2364 len = strlen(buf);
2365 assert(len < buflen, "Ran out of buffer room");
2366 jrelib_p = buf + len;
2367 snprintf(jrelib_p, buflen-len, "/jre/lib/%s", cpu_arch);
2368 if (0 != access(buf, F_OK)) {
2369 snprintf(jrelib_p, buflen-len, "/lib/%s", cpu_arch);
2370 }
2371
2372 if (0 == access(buf, F_OK)) {
2373 // Use current module name "libjvm.so"
2374 len = strlen(buf);
2375 snprintf(buf + len, buflen-len, "/hotspot/libjvm.so");
2376 } else {
2377 // Go back to path of .so
2378 rp = realpath(dli_fname, buf);
2379 if (rp == NULL) {
2380 return;
2381 }
2382 }
2383 }
2384 }
2385 }
2386
2387 strncpy(saved_jvm_path, buf, MAXPATHLEN);
2388 saved_jvm_path[MAXPATHLEN - 1] = '\0';
2389 }
2390
2391 void os::print_jni_name_prefix_on(outputStream* st, int args_size) {
2392 // no prefix required, not even "_"
2393 }
2394
2395 void os::print_jni_name_suffix_on(outputStream* st, int args_size) {
2396 // no suffix required
2397 }
2398
2399 ////////////////////////////////////////////////////////////////////////////////
2400 // sun.misc.Signal support
2401
2402 static volatile jint sigint_count = 0;
2403
2404 static void UserHandler(int sig, void *siginfo, void *context) {
2405 // 4511530 - sem_post is serialized and handled by the manager thread. When
2406 // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We
2407 // don't want to flood the manager thread with sem_post requests.
2408 if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1) {
2409 return;
2410 }
2411
2412 // Ctrl-C is pressed during error reporting, likely because the error
2413 // handler fails to abort. Let VM die immediately.
2414 if (sig == SIGINT && is_error_reported()) {
2415 os::die();
2416 }
2417
2418 os::signal_notify(sig);
2419 }
2420
2421 void* os::user_handler() {
2422 return CAST_FROM_FN_PTR(void*, UserHandler);
2423 }
2424
2425 class Semaphore : public StackObj {
2426 public:
2427 Semaphore();
2428 ~Semaphore();
2429 void signal();
2430 void wait();
2431 bool trywait();
2432 bool timedwait(unsigned int sec, int nsec);
2433 private:
2434 sem_t _semaphore;
2435 };
2436
2437 Semaphore::Semaphore() {
2438 sem_init(&_semaphore, 0, 0);
2439 }
2440
2441 Semaphore::~Semaphore() {
2442 sem_destroy(&_semaphore);
2443 }
2444
2445 void Semaphore::signal() {
2446 sem_post(&_semaphore);
2447 }
2448
2449 void Semaphore::wait() {
2450 sem_wait(&_semaphore);
2451 }
2452
2453 bool Semaphore::trywait() {
2454 return sem_trywait(&_semaphore) == 0;
2455 }
2456
2457 bool Semaphore::timedwait(unsigned int sec, int nsec) {
2458
2459 struct timespec ts;
2460 // Semaphore's are always associated with CLOCK_REALTIME
2461 os::Linux::clock_gettime(CLOCK_REALTIME, &ts);
2462 // see unpackTime for discussion on overflow checking
2463 if (sec >= MAX_SECS) {
2464 ts.tv_sec += MAX_SECS;
2465 ts.tv_nsec = 0;
2466 } else {
2467 ts.tv_sec += sec;
2468 ts.tv_nsec += nsec;
2469 if (ts.tv_nsec >= NANOSECS_PER_SEC) {
2470 ts.tv_nsec -= NANOSECS_PER_SEC;
2471 ++ts.tv_sec; // note: this must be <= max_secs
2472 }
2473 }
2474
2475 while (1) {
2476 int result = sem_timedwait(&_semaphore, &ts);
2477 if (result == 0) {
2478 return true;
2479 } else if (errno == EINTR) {
2480 continue;
2481 } else if (errno == ETIMEDOUT) {
2482 return false;
2483 } else {
2484 return false;
2485 }
2486 }
2487 }
2488
2489 extern "C" {
2490 typedef void (*sa_handler_t)(int);
2491 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *);
2492 }
2493
2494 void* os::signal(int signal_number, void* handler) {
2495 struct sigaction sigAct, oldSigAct;
2496
2497 sigfillset(&(sigAct.sa_mask));
2498 sigAct.sa_flags = SA_RESTART|SA_SIGINFO;
2499 sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler);
2500
2501 if (sigaction(signal_number, &sigAct, &oldSigAct)) {
2502 // -1 means registration failed
2503 return (void *)-1;
2504 }
2505
2506 return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler);
2507 }
2508
2509 void os::signal_raise(int signal_number) {
2510 ::raise(signal_number);
2511 }
2512
2513 // The following code is moved from os.cpp for making this
2514 // code platform specific, which it is by its very nature.
2515
2516 // Will be modified when max signal is changed to be dynamic
2517 int os::sigexitnum_pd() {
2518 return NSIG;
2519 }
2520
2521 // a counter for each possible signal value
2522 static volatile jint pending_signals[NSIG+1] = { 0 };
2523
2524 // Linux(POSIX) specific hand shaking semaphore.
2525 static sem_t sig_sem;
2526 static Semaphore sr_semaphore;
2527
2528 void os::signal_init_pd() {
2529 // Initialize signal structures
2530 ::memset((void*)pending_signals, 0, sizeof(pending_signals));
2531
2532 // Initialize signal semaphore
2533 ::sem_init(&sig_sem, 0, 0);
2534 }
2535
2536 void os::signal_notify(int sig) {
2537 Atomic::inc(&pending_signals[sig]);
2538 ::sem_post(&sig_sem);
2539 }
2540
2541 static int check_pending_signals(bool wait) {
2542 Atomic::store(0, &sigint_count);
2543 for (;;) {
2544 for (int i = 0; i < NSIG + 1; i++) {
2545 jint n = pending_signals[i];
2546 if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) {
2547 return i;
2548 }
2549 }
2550 if (!wait) {
2551 return -1;
2552 }
2553 JavaThread *thread = JavaThread::current();
2554 ThreadBlockInVM tbivm(thread);
2555
2556 bool threadIsSuspended;
2557 do {
2558 thread->set_suspend_equivalent();
2559 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
2560 ::sem_wait(&sig_sem);
2561
2562 // were we externally suspended while we were waiting?
2563 threadIsSuspended = thread->handle_special_suspend_equivalent_condition();
2564 if (threadIsSuspended) {
2565 // The semaphore has been incremented, but while we were waiting
2566 // another thread suspended us. We don't want to continue running
2567 // while suspended because that would surprise the thread that
2568 // suspended us.
2569 ::sem_post(&sig_sem);
2570
2571 thread->java_suspend_self();
2572 }
2573 } while (threadIsSuspended);
2574 }
2575 }
2576
2577 int os::signal_lookup() {
2578 return check_pending_signals(false);
2579 }
2580
2581 int os::signal_wait() {
2582 return check_pending_signals(true);
2583 }
2584
2585 ////////////////////////////////////////////////////////////////////////////////
2586 // Virtual Memory
2587
2588 int os::vm_page_size() {
2589 // Seems redundant as all get out
2590 assert(os::Linux::page_size() != -1, "must call os::init");
2591 return os::Linux::page_size();
2592 }
2593
2594 // Solaris allocates memory by pages.
2595 int os::vm_allocation_granularity() {
2596 assert(os::Linux::page_size() != -1, "must call os::init");
2597 return os::Linux::page_size();
2598 }
2599
2600 // Rationale behind this function:
2601 // current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable
2602 // mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get
2603 // samples for JITted code. Here we create private executable mapping over the code cache
2604 // and then we can use standard (well, almost, as mapping can change) way to provide
2605 // info for the reporting script by storing timestamp and location of symbol
2606 void linux_wrap_code(char* base, size_t size) {
2607 static volatile jint cnt = 0;
2608
2609 if (!UseOprofile) {
2610 return;
2611 }
2612
2613 char buf[PATH_MAX+1];
2614 int num = Atomic::add(1, &cnt);
2615
2616 snprintf(buf, sizeof(buf), "%s/hs-vm-%d-%d",
2617 os::get_temp_directory(), os::current_process_id(), num);
2618 unlink(buf);
2619
2620 int fd = ::open(buf, O_CREAT | O_RDWR, S_IRWXU);
2621
2622 if (fd != -1) {
2623 off_t rv = ::lseek(fd, size-2, SEEK_SET);
2624 if (rv != (off_t)-1) {
2625 if (::write(fd, "", 1) == 1) {
2626 mmap(base, size,
2627 PROT_READ|PROT_WRITE|PROT_EXEC,
2628 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0);
2629 }
2630 }
2631 ::close(fd);
2632 unlink(buf);
2633 }
2634 }
2635
2636 static bool recoverable_mmap_error(int err) {
2637 // See if the error is one we can let the caller handle. This
2638 // list of errno values comes from JBS-6843484. I can't find a
2639 // Linux man page that documents this specific set of errno
2640 // values so while this list currently matches Solaris, it may
2641 // change as we gain experience with this failure mode.
2642 switch (err) {
2643 case EBADF:
2644 case EINVAL:
2645 case ENOTSUP:
2646 // let the caller deal with these errors
2647 return true;
2648
2649 default:
2650 // Any remaining errors on this OS can cause our reserved mapping
2651 // to be lost. That can cause confusion where different data
2652 // structures think they have the same memory mapped. The worst
2653 // scenario is if both the VM and a library think they have the
2654 // same memory mapped.
2655 return false;
2656 }
2657 }
2658
2659 static void warn_fail_commit_memory(char* addr, size_t size, bool exec,
2660 int err) {
2661 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT
2662 ", %d) failed; error='%s' (errno=%d)", addr, size, exec,
2663 strerror(err), err);
2664 }
2665
2666 static void warn_fail_commit_memory(char* addr, size_t size,
2667 size_t alignment_hint, bool exec,
2668 int err) {
2669 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT
2670 ", " SIZE_FORMAT ", %d) failed; error='%s' (errno=%d)", addr, size,
2671 alignment_hint, exec, strerror(err), err);
2672 }
2673
2674 // NOTE: Linux kernel does not really reserve the pages for us.
2675 // All it does is to check if there are enough free pages
2676 // left at the time of mmap(). This could be a potential
2677 // problem.
2678 int os::Linux::commit_memory_impl(char* addr, size_t size, bool exec) {
2679 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
2680 uintptr_t res = (uintptr_t) ::mmap(addr, size, prot,
2681 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0);
2682 if (res != (uintptr_t) MAP_FAILED) {
2683 if (UseNUMAInterleaving) {
2684 numa_make_global(addr, size);
2685 }
2686 return 0;
2687 }
2688
2689 int err = errno; // save errno from mmap() call above
2690
2691 if (!recoverable_mmap_error(err)) {
2692 warn_fail_commit_memory(addr, size, exec, err);
2693 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, "committing reserved memory.");
2694 }
2695
2696 return err;
2697 }
2698
2699 bool os::pd_commit_memory(char* addr, size_t size, bool exec) {
2700 return os::Linux::commit_memory_impl(addr, size, exec) == 0;
2701 }
2702
2703 void os::pd_commit_memory_or_exit(char* addr, size_t size, bool exec,
2704 const char* mesg) {
2705 assert(mesg != NULL, "mesg must be specified");
2706 int err = os::Linux::commit_memory_impl(addr, size, exec);
2707 if (err != 0) {
2708 // the caller wants all commit errors to exit with the specified mesg:
2709 warn_fail_commit_memory(addr, size, exec, err);
2710 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg);
2711 }
2712 }
2713
2714 // Define MAP_HUGETLB here so we can build HotSpot on old systems.
2715 #ifndef MAP_HUGETLB
2716 #define MAP_HUGETLB 0x40000
2717 #endif
2718
2719 // Define MADV_HUGEPAGE here so we can build HotSpot on old systems.
2720 #ifndef MADV_HUGEPAGE
2721 #define MADV_HUGEPAGE 14
2722 #endif
2723
2724 int os::Linux::commit_memory_impl(char* addr, size_t size,
2725 size_t alignment_hint, bool exec) {
2726 int err = os::Linux::commit_memory_impl(addr, size, exec);
2727 if (err == 0) {
2728 realign_memory(addr, size, alignment_hint);
2729 }
2730 return err;
2731 }
2732
2733 bool os::pd_commit_memory(char* addr, size_t size, size_t alignment_hint,
2734 bool exec) {
2735 return os::Linux::commit_memory_impl(addr, size, alignment_hint, exec) == 0;
2736 }
2737
2738 void os::pd_commit_memory_or_exit(char* addr, size_t size,
2739 size_t alignment_hint, bool exec,
2740 const char* mesg) {
2741 assert(mesg != NULL, "mesg must be specified");
2742 int err = os::Linux::commit_memory_impl(addr, size, alignment_hint, exec);
2743 if (err != 0) {
2744 // the caller wants all commit errors to exit with the specified mesg:
2745 warn_fail_commit_memory(addr, size, alignment_hint, exec, err);
2746 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg);
2747 }
2748 }
2749
2750 void os::pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint) {
2751 if (UseTransparentHugePages && alignment_hint > (size_t)vm_page_size()) {
2752 // We don't check the return value: madvise(MADV_HUGEPAGE) may not
2753 // be supported or the memory may already be backed by huge pages.
2754 ::madvise(addr, bytes, MADV_HUGEPAGE);
2755 }
2756 }
2757
2758 void os::pd_free_memory(char *addr, size_t bytes, size_t alignment_hint) {
2759 // This method works by doing an mmap over an existing mmaping and effectively discarding
2760 // the existing pages. However it won't work for SHM-based large pages that cannot be
2761 // uncommitted at all. We don't do anything in this case to avoid creating a segment with
2762 // small pages on top of the SHM segment. This method always works for small pages, so we
2763 // allow that in any case.
2764 if (alignment_hint <= (size_t)os::vm_page_size() || can_commit_large_page_memory()) {
2765 commit_memory(addr, bytes, alignment_hint, !ExecMem);
2766 }
2767 }
2768
2769 void os::numa_make_global(char *addr, size_t bytes) {
2770 Linux::numa_interleave_memory(addr, bytes);
2771 }
2772
2773 // Define for numa_set_bind_policy(int). Setting the argument to 0 will set the
2774 // bind policy to MPOL_PREFERRED for the current thread.
2775 #define USE_MPOL_PREFERRED 0
2776
2777 void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) {
2778 // To make NUMA and large pages more robust when both enabled, we need to ease
2779 // the requirements on where the memory should be allocated. MPOL_BIND is the
2780 // default policy and it will force memory to be allocated on the specified
2781 // node. Changing this to MPOL_PREFERRED will prefer to allocate the memory on
2782 // the specified node, but will not force it. Using this policy will prevent
2783 // getting SIGBUS when trying to allocate large pages on NUMA nodes with no
2784 // free large pages.
2785 Linux::numa_set_bind_policy(USE_MPOL_PREFERRED);
2786 Linux::numa_tonode_memory(addr, bytes, lgrp_hint);
2787 }
2788
2789 bool os::numa_topology_changed() { return false; }
2790
2791 size_t os::numa_get_groups_num() {
2792 int max_node = Linux::numa_max_node();
2793 return max_node > 0 ? max_node + 1 : 1;
2794 }
2795
2796 int os::numa_get_group_id() {
2797 int cpu_id = Linux::sched_getcpu();
2798 if (cpu_id != -1) {
2799 int lgrp_id = Linux::get_node_by_cpu(cpu_id);
2800 if (lgrp_id != -1) {
2801 return lgrp_id;
2802 }
2803 }
2804 return 0;
2805 }
2806
2807 size_t os::numa_get_leaf_groups(int *ids, size_t size) {
2808 for (size_t i = 0; i < size; i++) {
2809 ids[i] = i;
2810 }
2811 return size;
2812 }
2813
2814 bool os::get_page_info(char *start, page_info* info) {
2815 return false;
2816 }
2817
2818 char *os::scan_pages(char *start, char* end, page_info* page_expected,
2819 page_info* page_found) {
2820 return end;
2821 }
2822
2823
2824 int os::Linux::sched_getcpu_syscall(void) {
2825 unsigned int cpu;
2826 int retval = -1;
2827
2828 #if defined(IA32)
2829 #ifndef SYS_getcpu
2830 #define SYS_getcpu 318
2831 #endif
2832 retval = syscall(SYS_getcpu, &cpu, NULL, NULL);
2833 #elif defined(AMD64)
2834 // Unfortunately we have to bring all these macros here from vsyscall.h
2835 // to be able to compile on old linuxes.
2836 #define __NR_vgetcpu 2
2837 #define VSYSCALL_START (-10UL << 20)
2838 #define VSYSCALL_SIZE 1024
2839 #define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr))
2840 typedef long (*vgetcpu_t)(unsigned int *cpu, unsigned int *node, unsigned long *tcache);
2841 vgetcpu_t vgetcpu = (vgetcpu_t)VSYSCALL_ADDR(__NR_vgetcpu);
2842 retval = vgetcpu(&cpu, NULL, NULL);
2843 #endif
2844
2845 return (retval == -1) ? retval : cpu;
2846 }
2847
2848 // Something to do with the numa-aware allocator needs these symbols
2849 extern "C" JNIEXPORT void numa_warn(int number, char *where, ...) { }
2850 extern "C" JNIEXPORT void numa_error(char *where) { }
2851 extern "C" JNIEXPORT int fork1() { return fork(); }
2852
2853
2854 // If we are running with libnuma version > 2, then we should
2855 // be trying to use symbols with versions 1.1
2856 // If we are running with earlier version, which did not have symbol versions,
2857 // we should use the base version.
2858 void* os::Linux::libnuma_dlsym(void* handle, const char *name) {
2859 void *f = dlvsym(handle, name, "libnuma_1.1");
2860 if (f == NULL) {
2861 f = dlsym(handle, name);
2862 }
2863 return f;
2864 }
2865
2866 bool os::Linux::libnuma_init() {
2867 // sched_getcpu() should be in libc.
2868 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t,
2869 dlsym(RTLD_DEFAULT, "sched_getcpu")));
2870
2871 // If it's not, try a direct syscall.
2872 if (sched_getcpu() == -1) {
2873 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t,
2874 (void*)&sched_getcpu_syscall));
2875 }
2876
2877 if (sched_getcpu() != -1) { // Does it work?
2878 void *handle = dlopen("libnuma.so.1", RTLD_LAZY);
2879 if (handle != NULL) {
2880 set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t,
2881 libnuma_dlsym(handle, "numa_node_to_cpus")));
2882 set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t,
2883 libnuma_dlsym(handle, "numa_max_node")));
2884 set_numa_available(CAST_TO_FN_PTR(numa_available_func_t,
2885 libnuma_dlsym(handle, "numa_available")));
2886 set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t,
2887 libnuma_dlsym(handle, "numa_tonode_memory")));
2888 set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t,
2889 libnuma_dlsym(handle, "numa_interleave_memory")));
2890 set_numa_set_bind_policy(CAST_TO_FN_PTR(numa_set_bind_policy_func_t,
2891 libnuma_dlsym(handle, "numa_set_bind_policy")));
2892
2893
2894 if (numa_available() != -1) {
2895 set_numa_all_nodes((unsigned long*)libnuma_dlsym(handle, "numa_all_nodes"));
2896 // Create a cpu -> node mapping
2897 _cpu_to_node = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<int>(0, true);
2898 rebuild_cpu_to_node_map();
2899 return true;
2900 }
2901 }
2902 }
2903 return false;
2904 }
2905
2906 // rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id.
2907 // The table is later used in get_node_by_cpu().
2908 void os::Linux::rebuild_cpu_to_node_map() {
2909 const size_t NCPUS = 32768; // Since the buffer size computation is very obscure
2910 // in libnuma (possible values are starting from 16,
2911 // and continuing up with every other power of 2, but less
2912 // than the maximum number of CPUs supported by kernel), and
2913 // is a subject to change (in libnuma version 2 the requirements
2914 // are more reasonable) we'll just hardcode the number they use
2915 // in the library.
2916 const size_t BitsPerCLong = sizeof(long) * CHAR_BIT;
2917
2918 size_t cpu_num = os::active_processor_count();
2919 size_t cpu_map_size = NCPUS / BitsPerCLong;
2920 size_t cpu_map_valid_size =
2921 MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size);
2922
2923 cpu_to_node()->clear();
2924 cpu_to_node()->at_grow(cpu_num - 1);
2925 size_t node_num = numa_get_groups_num();
2926
2927 unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size, mtInternal);
2928 for (size_t i = 0; i < node_num; i++) {
2929 if (numa_node_to_cpus(i, cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) {
2930 for (size_t j = 0; j < cpu_map_valid_size; j++) {
2931 if (cpu_map[j] != 0) {
2932 for (size_t k = 0; k < BitsPerCLong; k++) {
2933 if (cpu_map[j] & (1UL << k)) {
2934 cpu_to_node()->at_put(j * BitsPerCLong + k, i);
2935 }
2936 }
2937 }
2938 }
2939 }
2940 }
2941 FREE_C_HEAP_ARRAY(unsigned long, cpu_map);
2942 }
2943
2944 int os::Linux::get_node_by_cpu(int cpu_id) {
2945 if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) {
2946 return cpu_to_node()->at(cpu_id);
2947 }
2948 return -1;
2949 }
2950
2951 GrowableArray<int>* os::Linux::_cpu_to_node;
2952 os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu;
2953 os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus;
2954 os::Linux::numa_max_node_func_t os::Linux::_numa_max_node;
2955 os::Linux::numa_available_func_t os::Linux::_numa_available;
2956 os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory;
2957 os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory;
2958 os::Linux::numa_set_bind_policy_func_t os::Linux::_numa_set_bind_policy;
2959 unsigned long* os::Linux::_numa_all_nodes;
2960
2961 bool os::pd_uncommit_memory(char* addr, size_t size) {
2962 uintptr_t res = (uintptr_t) ::mmap(addr, size, PROT_NONE,
2963 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0);
2964 return res != (uintptr_t) MAP_FAILED;
2965 }
2966
2967 static address get_stack_commited_bottom(address bottom, size_t size) {
2968 address nbot = bottom;
2969 address ntop = bottom + size;
2970
2971 size_t page_sz = os::vm_page_size();
2972 unsigned pages = size / page_sz;
2973
2974 unsigned char vec[1];
2975 unsigned imin = 1, imax = pages + 1, imid;
2976 int mincore_return_value = 0;
2977
2978 assert(imin <= imax, "Unexpected page size");
2979
2980 while (imin < imax) {
2981 imid = (imax + imin) / 2;
2982 nbot = ntop - (imid * page_sz);
2983
2984 // Use a trick with mincore to check whether the page is mapped or not.
2985 // mincore sets vec to 1 if page resides in memory and to 0 if page
2986 // is swapped output but if page we are asking for is unmapped
2987 // it returns -1,ENOMEM
2988 mincore_return_value = mincore(nbot, page_sz, vec);
2989
2990 if (mincore_return_value == -1) {
2991 // Page is not mapped go up
2992 // to find first mapped page
2993 if (errno != EAGAIN) {
2994 assert(errno == ENOMEM, "Unexpected mincore errno");
2995 imax = imid;
2996 }
2997 } else {
2998 // Page is mapped go down
2999 // to find first not mapped page
3000 imin = imid + 1;
3001 }
3002 }
3003
3004 nbot = nbot + page_sz;
3005
3006 // Adjust stack bottom one page up if last checked page is not mapped
3007 if (mincore_return_value == -1) {
3008 nbot = nbot + page_sz;
3009 }
3010
3011 return nbot;
3012 }
3013
3014
3015 // Linux uses a growable mapping for the stack, and if the mapping for
3016 // the stack guard pages is not removed when we detach a thread the
3017 // stack cannot grow beyond the pages where the stack guard was
3018 // mapped. If at some point later in the process the stack expands to
3019 // that point, the Linux kernel cannot expand the stack any further
3020 // because the guard pages are in the way, and a segfault occurs.
3021 //
3022 // However, it's essential not to split the stack region by unmapping
3023 // a region (leaving a hole) that's already part of the stack mapping,
3024 // so if the stack mapping has already grown beyond the guard pages at
3025 // the time we create them, we have to truncate the stack mapping.
3026 // So, we need to know the extent of the stack mapping when
3027 // create_stack_guard_pages() is called.
3028
3029 // We only need this for stacks that are growable: at the time of
3030 // writing thread stacks don't use growable mappings (i.e. those
3031 // creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this
3032 // only applies to the main thread.
3033
3034 // If the (growable) stack mapping already extends beyond the point
3035 // where we're going to put our guard pages, truncate the mapping at
3036 // that point by munmap()ping it. This ensures that when we later
3037 // munmap() the guard pages we don't leave a hole in the stack
3038 // mapping. This only affects the main/initial thread
3039
3040 bool os::pd_create_stack_guard_pages(char* addr, size_t size) {
3041 if (os::Linux::is_initial_thread()) {
3042 // As we manually grow stack up to bottom inside create_attached_thread(),
3043 // it's likely that os::Linux::initial_thread_stack_bottom is mapped and
3044 // we don't need to do anything special.
3045 // Check it first, before calling heavy function.
3046 uintptr_t stack_extent = (uintptr_t) os::Linux::initial_thread_stack_bottom();
3047 unsigned char vec[1];
3048
3049 if (mincore((address)stack_extent, os::vm_page_size(), vec) == -1) {
3050 // Fallback to slow path on all errors, including EAGAIN
3051 stack_extent = (uintptr_t) get_stack_commited_bottom(
3052 os::Linux::initial_thread_stack_bottom(),
3053 (size_t)addr - stack_extent);
3054 }
3055
3056 if (stack_extent < (uintptr_t)addr) {
3057 ::munmap((void*)stack_extent, (uintptr_t)(addr - stack_extent));
3058 }
3059 }
3060
3061 return os::commit_memory(addr, size, !ExecMem);
3062 }
3063
3064 // If this is a growable mapping, remove the guard pages entirely by
3065 // munmap()ping them. If not, just call uncommit_memory(). This only
3066 // affects the main/initial thread, but guard against future OS changes
3067 // It's safe to always unmap guard pages for initial thread because we
3068 // always place it right after end of the mapped region
3069
3070 bool os::remove_stack_guard_pages(char* addr, size_t size) {
3071 uintptr_t stack_extent, stack_base;
3072
3073 if (os::Linux::is_initial_thread()) {
3074 return ::munmap(addr, size) == 0;
3075 }
3076
3077 return os::uncommit_memory(addr, size);
3078 }
3079
3080 static address _highest_vm_reserved_address = NULL;
3081
3082 // If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory
3083 // at 'requested_addr'. If there are existing memory mappings at the same
3084 // location, however, they will be overwritten. If 'fixed' is false,
3085 // 'requested_addr' is only treated as a hint, the return value may or
3086 // may not start from the requested address. Unlike Linux mmap(), this
3087 // function returns NULL to indicate failure.
3088 static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) {
3089 char * addr;
3090 int flags;
3091
3092 flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS;
3093 if (fixed) {
3094 assert((uintptr_t)requested_addr % os::Linux::page_size() == 0, "unaligned address");
3095 flags |= MAP_FIXED;
3096 }
3097
3098 // Map reserved/uncommitted pages PROT_NONE so we fail early if we
3099 // touch an uncommitted page. Otherwise, the read/write might
3100 // succeed if we have enough swap space to back the physical page.
3101 addr = (char*)::mmap(requested_addr, bytes, PROT_NONE,
3102 flags, -1, 0);
3103
3104 if (addr != MAP_FAILED) {
3105 // anon_mmap() should only get called during VM initialization,
3106 // don't need lock (actually we can skip locking even it can be called
3107 // from multiple threads, because _highest_vm_reserved_address is just a
3108 // hint about the upper limit of non-stack memory regions.)
3109 if ((address)addr + bytes > _highest_vm_reserved_address) {
3110 _highest_vm_reserved_address = (address)addr + bytes;
3111 }
3112 }
3113
3114 return addr == MAP_FAILED ? NULL : addr;
3115 }
3116
3117 // Don't update _highest_vm_reserved_address, because there might be memory
3118 // regions above addr + size. If so, releasing a memory region only creates
3119 // a hole in the address space, it doesn't help prevent heap-stack collision.
3120 //
3121 static int anon_munmap(char * addr, size_t size) {
3122 return ::munmap(addr, size) == 0;
3123 }
3124
3125 char* os::pd_reserve_memory(size_t bytes, char* requested_addr,
3126 size_t alignment_hint) {
3127 return anon_mmap(requested_addr, bytes, (requested_addr != NULL));
3128 }
3129
3130 bool os::pd_release_memory(char* addr, size_t size) {
3131 return anon_munmap(addr, size);
3132 }
3133
3134 static address highest_vm_reserved_address() {
3135 return _highest_vm_reserved_address;
3136 }
3137
3138 static bool linux_mprotect(char* addr, size_t size, int prot) {
3139 // Linux wants the mprotect address argument to be page aligned.
3140 char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::page_size());
3141
3142 // According to SUSv3, mprotect() should only be used with mappings
3143 // established by mmap(), and mmap() always maps whole pages. Unaligned
3144 // 'addr' likely indicates problem in the VM (e.g. trying to change
3145 // protection of malloc'ed or statically allocated memory). Check the
3146 // caller if you hit this assert.
3147 assert(addr == bottom, "sanity check");
3148
3149 size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Linux::page_size());
3150 return ::mprotect(bottom, size, prot) == 0;
3151 }
3152
3153 // Set protections specified
3154 bool os::protect_memory(char* addr, size_t bytes, ProtType prot,
3155 bool is_committed) {
3156 unsigned int p = 0;
3157 switch (prot) {
3158 case MEM_PROT_NONE: p = PROT_NONE; break;
3159 case MEM_PROT_READ: p = PROT_READ; break;
3160 case MEM_PROT_RW: p = PROT_READ|PROT_WRITE; break;
3161 case MEM_PROT_RWX: p = PROT_READ|PROT_WRITE|PROT_EXEC; break;
3162 default:
3163 ShouldNotReachHere();
3164 }
3165 // is_committed is unused.
3166 return linux_mprotect(addr, bytes, p);
3167 }
3168
3169 bool os::guard_memory(char* addr, size_t size) {
3170 return linux_mprotect(addr, size, PROT_NONE);
3171 }
3172
3173 bool os::unguard_memory(char* addr, size_t size) {
3174 return linux_mprotect(addr, size, PROT_READ|PROT_WRITE);
3175 }
3176
3177 bool os::Linux::transparent_huge_pages_sanity_check(bool warn,
3178 size_t page_size) {
3179 bool result = false;
3180 void *p = mmap(NULL, page_size * 2, PROT_READ|PROT_WRITE,
3181 MAP_ANONYMOUS|MAP_PRIVATE,
3182 -1, 0);
3183 if (p != MAP_FAILED) {
3184 void *aligned_p = align_ptr_up(p, page_size);
3185
3186 result = madvise(aligned_p, page_size, MADV_HUGEPAGE) == 0;
3187
3188 munmap(p, page_size * 2);
3189 }
3190
3191 if (warn && !result) {
3192 warning("TransparentHugePages is not supported by the operating system.");
3193 }
3194
3195 return result;
3196 }
3197
3198 bool os::Linux::hugetlbfs_sanity_check(bool warn, size_t page_size) {
3199 bool result = false;
3200 void *p = mmap(NULL, page_size, PROT_READ|PROT_WRITE,
3201 MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB,
3202 -1, 0);
3203
3204 if (p != MAP_FAILED) {
3205 // We don't know if this really is a huge page or not.
3206 FILE *fp = fopen("/proc/self/maps", "r");
3207 if (fp) {
3208 while (!feof(fp)) {
3209 char chars[257];
3210 long x = 0;
3211 if (fgets(chars, sizeof(chars), fp)) {
3212 if (sscanf(chars, "%lx-%*x", &x) == 1
3213 && x == (long)p) {
3214 if (strstr (chars, "hugepage")) {
3215 result = true;
3216 break;
3217 }
3218 }
3219 }
3220 }
3221 fclose(fp);
3222 }
3223 munmap(p, page_size);
3224 }
3225
3226 if (warn && !result) {
3227 warning("HugeTLBFS is not supported by the operating system.");
3228 }
3229
3230 return result;
3231 }
3232
3233 // Set the coredump_filter bits to include largepages in core dump (bit 6)
3234 //
3235 // From the coredump_filter documentation:
3236 //
3237 // - (bit 0) anonymous private memory
3238 // - (bit 1) anonymous shared memory
3239 // - (bit 2) file-backed private memory
3240 // - (bit 3) file-backed shared memory
3241 // - (bit 4) ELF header pages in file-backed private memory areas (it is
3242 // effective only if the bit 2 is cleared)
3243 // - (bit 5) hugetlb private memory
3244 // - (bit 6) hugetlb shared memory
3245 //
3246 static void set_coredump_filter(void) {
3247 FILE *f;
3248 long cdm;
3249
3250 if ((f = fopen("/proc/self/coredump_filter", "r+")) == NULL) {
3251 return;
3252 }
3253
3254 if (fscanf(f, "%lx", &cdm) != 1) {
3255 fclose(f);
3256 return;
3257 }
3258
3259 rewind(f);
3260
3261 if ((cdm & LARGEPAGES_BIT) == 0) {
3262 cdm |= LARGEPAGES_BIT;
3263 fprintf(f, "%#lx", cdm);
3264 }
3265
3266 fclose(f);
3267 }
3268
3269 // Large page support
3270
3271 static size_t _large_page_size = 0;
3272
3273 size_t os::Linux::find_large_page_size() {
3274 size_t large_page_size = 0;
3275
3276 // large_page_size on Linux is used to round up heap size. x86 uses either
3277 // 2M or 4M page, depending on whether PAE (Physical Address Extensions)
3278 // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use
3279 // page as large as 256M.
3280 //
3281 // Here we try to figure out page size by parsing /proc/meminfo and looking
3282 // for a line with the following format:
3283 // Hugepagesize: 2048 kB
3284 //
3285 // If we can't determine the value (e.g. /proc is not mounted, or the text
3286 // format has been changed), we'll use the largest page size supported by
3287 // the processor.
3288
3289 #ifndef ZERO
3290 large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M)
3291 ARM_ONLY(2 * M) PPC_ONLY(4 * M);
3292 #endif // ZERO
3293
3294 FILE *fp = fopen("/proc/meminfo", "r");
3295 if (fp) {
3296 while (!feof(fp)) {
3297 int x = 0;
3298 char buf[16];
3299 if (fscanf(fp, "Hugepagesize: %d", &x) == 1) {
3300 if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) {
3301 large_page_size = x * K;
3302 break;
3303 }
3304 } else {
3305 // skip to next line
3306 for (;;) {
3307 int ch = fgetc(fp);
3308 if (ch == EOF || ch == (int)'\n') break;
3309 }
3310 }
3311 }
3312 fclose(fp);
3313 }
3314
3315 if (!FLAG_IS_DEFAULT(LargePageSizeInBytes) && LargePageSizeInBytes != large_page_size) {
3316 warning("Setting LargePageSizeInBytes has no effect on this OS. Large page size is "
3317 SIZE_FORMAT "%s.", byte_size_in_proper_unit(large_page_size),
3318 proper_unit_for_byte_size(large_page_size));
3319 }
3320
3321 return large_page_size;
3322 }
3323
3324 size_t os::Linux::setup_large_page_size() {
3325 _large_page_size = Linux::find_large_page_size();
3326 const size_t default_page_size = (size_t)Linux::page_size();
3327 if (_large_page_size > default_page_size) {
3328 _page_sizes[0] = _large_page_size;
3329 _page_sizes[1] = default_page_size;
3330 _page_sizes[2] = 0;
3331 }
3332
3333 return _large_page_size;
3334 }
3335
3336 bool os::Linux::setup_large_page_type(size_t page_size) {
3337 if (FLAG_IS_DEFAULT(UseHugeTLBFS) &&
3338 FLAG_IS_DEFAULT(UseSHM) &&
3339 FLAG_IS_DEFAULT(UseTransparentHugePages)) {
3340
3341 // The type of large pages has not been specified by the user.
3342
3343 // Try UseHugeTLBFS and then UseSHM.
3344 UseHugeTLBFS = UseSHM = true;
3345
3346 // Don't try UseTransparentHugePages since there are known
3347 // performance issues with it turned on. This might change in the future.
3348 UseTransparentHugePages = false;
3349 }
3350
3351 if (UseTransparentHugePages) {
3352 bool warn_on_failure = !FLAG_IS_DEFAULT(UseTransparentHugePages);
3353 if (transparent_huge_pages_sanity_check(warn_on_failure, page_size)) {
3354 UseHugeTLBFS = false;
3355 UseSHM = false;
3356 return true;
3357 }
3358 UseTransparentHugePages = false;
3359 }
3360
3361 if (UseHugeTLBFS) {
3362 bool warn_on_failure = !FLAG_IS_DEFAULT(UseHugeTLBFS);
3363 if (hugetlbfs_sanity_check(warn_on_failure, page_size)) {
3364 UseSHM = false;
3365 return true;
3366 }
3367 UseHugeTLBFS = false;
3368 }
3369
3370 return UseSHM;
3371 }
3372
3373 void os::large_page_init() {
3374 if (!UseLargePages &&
3375 !UseTransparentHugePages &&
3376 !UseHugeTLBFS &&
3377 !UseSHM) {
3378 // Not using large pages.
3379 return;
3380 }
3381
3382 if (!FLAG_IS_DEFAULT(UseLargePages) && !UseLargePages) {
3383 // The user explicitly turned off large pages.
3384 // Ignore the rest of the large pages flags.
3385 UseTransparentHugePages = false;
3386 UseHugeTLBFS = false;
3387 UseSHM = false;
3388 return;
3389 }
3390
3391 size_t large_page_size = Linux::setup_large_page_size();
3392 UseLargePages = Linux::setup_large_page_type(large_page_size);
3393
3394 set_coredump_filter();
3395 }
3396
3397 #ifndef SHM_HUGETLB
3398 #define SHM_HUGETLB 04000
3399 #endif
3400
3401 char* os::Linux::reserve_memory_special_shm(size_t bytes, size_t alignment,
3402 char* req_addr, bool exec) {
3403 // "exec" is passed in but not used. Creating the shared image for
3404 // the code cache doesn't have an SHM_X executable permission to check.
3405 assert(UseLargePages && UseSHM, "only for SHM large pages");
3406 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address");
3407
3408 if (!is_size_aligned(bytes, os::large_page_size()) || alignment > os::large_page_size()) {
3409 return NULL; // Fallback to small pages.
3410 }
3411
3412 key_t key = IPC_PRIVATE;
3413 char *addr;
3414
3415 bool warn_on_failure = UseLargePages &&
3416 (!FLAG_IS_DEFAULT(UseLargePages) ||
3417 !FLAG_IS_DEFAULT(UseSHM) ||
3418 !FLAG_IS_DEFAULT(LargePageSizeInBytes));
3419 char msg[128];
3420
3421 // Create a large shared memory region to attach to based on size.
3422 // Currently, size is the total size of the heap
3423 int shmid = shmget(key, bytes, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W);
3424 if (shmid == -1) {
3425 // Possible reasons for shmget failure:
3426 // 1. shmmax is too small for Java heap.
3427 // > check shmmax value: cat /proc/sys/kernel/shmmax
3428 // > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax
3429 // 2. not enough large page memory.
3430 // > check available large pages: cat /proc/meminfo
3431 // > increase amount of large pages:
3432 // echo new_value > /proc/sys/vm/nr_hugepages
3433 // Note 1: different Linux may use different name for this property,
3434 // e.g. on Redhat AS-3 it is "hugetlb_pool".
3435 // Note 2: it's possible there's enough physical memory available but
3436 // they are so fragmented after a long run that they can't
3437 // coalesce into large pages. Try to reserve large pages when
3438 // the system is still "fresh".
3439 if (warn_on_failure) {
3440 jio_snprintf(msg, sizeof(msg), "Failed to reserve shared memory (errno = %d).", errno);
3441 warning("%s", msg);
3442 }
3443 return NULL;
3444 }
3445
3446 // attach to the region
3447 addr = (char*)shmat(shmid, req_addr, 0);
3448 int err = errno;
3449
3450 // Remove shmid. If shmat() is successful, the actual shared memory segment
3451 // will be deleted when it's detached by shmdt() or when the process
3452 // terminates. If shmat() is not successful this will remove the shared
3453 // segment immediately.
3454 shmctl(shmid, IPC_RMID, NULL);
3455
3456 if ((intptr_t)addr == -1) {
3457 if (warn_on_failure) {
3458 jio_snprintf(msg, sizeof(msg), "Failed to attach shared memory (errno = %d).", err);
3459 warning("%s", msg);
3460 }
3461 return NULL;
3462 }
3463
3464 return addr;
3465 }
3466
3467 static void warn_on_large_pages_failure(char* req_addr, size_t bytes,
3468 int error) {
3469 assert(error == ENOMEM, "Only expect to fail if no memory is available");
3470
3471 bool warn_on_failure = UseLargePages &&
3472 (!FLAG_IS_DEFAULT(UseLargePages) ||
3473 !FLAG_IS_DEFAULT(UseHugeTLBFS) ||
3474 !FLAG_IS_DEFAULT(LargePageSizeInBytes));
3475
3476 if (warn_on_failure) {
3477 char msg[128];
3478 jio_snprintf(msg, sizeof(msg), "Failed to reserve large pages memory req_addr: "
3479 PTR_FORMAT " bytes: " SIZE_FORMAT " (errno = %d).", req_addr, bytes, error);
3480 warning("%s", msg);
3481 }
3482 }
3483
3484 char* os::Linux::reserve_memory_special_huge_tlbfs_only(size_t bytes,
3485 char* req_addr,
3486 bool exec) {
3487 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages");
3488 assert(is_size_aligned(bytes, os::large_page_size()), "Unaligned size");
3489 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address");
3490
3491 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
3492 char* addr = (char*)::mmap(req_addr, bytes, prot,
3493 MAP_PRIVATE|MAP_ANONYMOUS|MAP_HUGETLB,
3494 -1, 0);
3495
3496 if (addr == MAP_FAILED) {
3497 warn_on_large_pages_failure(req_addr, bytes, errno);
3498 return NULL;
3499 }
3500
3501 assert(is_ptr_aligned(addr, os::large_page_size()), "Must be");
3502
3503 return addr;
3504 }
3505
3506 char* os::Linux::reserve_memory_special_huge_tlbfs_mixed(size_t bytes,
3507 size_t alignment,
3508 char* req_addr,
3509 bool exec) {
3510 size_t large_page_size = os::large_page_size();
3511
3512 assert(bytes >= large_page_size, "Shouldn't allocate large pages for small sizes");
3513
3514 // Allocate small pages.
3515
3516 char* start;
3517 if (req_addr != NULL) {
3518 assert(is_ptr_aligned(req_addr, alignment), "Must be");
3519 assert(is_size_aligned(bytes, alignment), "Must be");
3520 start = os::reserve_memory(bytes, req_addr);
3521 assert(start == NULL || start == req_addr, "Must be");
3522 } else {
3523 start = os::reserve_memory_aligned(bytes, alignment);
3524 }
3525
3526 if (start == NULL) {
3527 return NULL;
3528 }
3529
3530 assert(is_ptr_aligned(start, alignment), "Must be");
3531
3532 if (MemTracker::tracking_level() > NMT_minimal) {
3533 // os::reserve_memory_special will record this memory area.
3534 // Need to release it here to prevent overlapping reservations.
3535 Tracker tkr = MemTracker::get_virtual_memory_release_tracker();
3536 tkr.record((address)start, bytes);
3537 }
3538
3539 char* end = start + bytes;
3540
3541 // Find the regions of the allocated chunk that can be promoted to large pages.
3542 char* lp_start = (char*)align_ptr_up(start, large_page_size);
3543 char* lp_end = (char*)align_ptr_down(end, large_page_size);
3544
3545 size_t lp_bytes = lp_end - lp_start;
3546
3547 assert(is_size_aligned(lp_bytes, large_page_size), "Must be");
3548
3549 if (lp_bytes == 0) {
3550 // The mapped region doesn't even span the start and the end of a large page.
3551 // Fall back to allocate a non-special area.
3552 ::munmap(start, end - start);
3553 return NULL;
3554 }
3555
3556 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
3557
3558
3559 void* result;
3560
3561 if (start != lp_start) {
3562 result = ::mmap(start, lp_start - start, prot,
3563 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED,
3564 -1, 0);
3565 if (result == MAP_FAILED) {
3566 ::munmap(lp_start, end - lp_start);
3567 return NULL;
3568 }
3569 }
3570
3571 result = ::mmap(lp_start, lp_bytes, prot,
3572 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED|MAP_HUGETLB,
3573 -1, 0);
3574 if (result == MAP_FAILED) {
3575 warn_on_large_pages_failure(req_addr, bytes, errno);
3576 // If the mmap above fails, the large pages region will be unmapped and we
3577 // have regions before and after with small pages. Release these regions.
3578 //
3579 // | mapped | unmapped | mapped |
3580 // ^ ^ ^ ^
3581 // start lp_start lp_end end
3582 //
3583 ::munmap(start, lp_start - start);
3584 ::munmap(lp_end, end - lp_end);
3585 return NULL;
3586 }
3587
3588 if (lp_end != end) {
3589 result = ::mmap(lp_end, end - lp_end, prot,
3590 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED,
3591 -1, 0);
3592 if (result == MAP_FAILED) {
3593 ::munmap(start, lp_end - start);
3594 return NULL;
3595 }
3596 }
3597
3598 return start;
3599 }
3600
3601 char* os::Linux::reserve_memory_special_huge_tlbfs(size_t bytes,
3602 size_t alignment,
3603 char* req_addr,
3604 bool exec) {
3605 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages");
3606 assert(is_ptr_aligned(req_addr, alignment), "Must be");
3607 assert(is_power_of_2(alignment), "Must be");
3608 assert(is_power_of_2(os::large_page_size()), "Must be");
3609 assert(bytes >= os::large_page_size(), "Shouldn't allocate large pages for small sizes");
3610
3611 if (is_size_aligned(bytes, os::large_page_size()) && alignment <= os::large_page_size()) {
3612 return reserve_memory_special_huge_tlbfs_only(bytes, req_addr, exec);
3613 } else {
3614 return reserve_memory_special_huge_tlbfs_mixed(bytes, alignment, req_addr, exec);
3615 }
3616 }
3617
3618 char* os::reserve_memory_special(size_t bytes, size_t alignment,
3619 char* req_addr, bool exec) {
3620 assert(UseLargePages, "only for large pages");
3621
3622 char* addr;
3623 if (UseSHM) {
3624 addr = os::Linux::reserve_memory_special_shm(bytes, alignment, req_addr, exec);
3625 } else {
3626 assert(UseHugeTLBFS, "must be");
3627 addr = os::Linux::reserve_memory_special_huge_tlbfs(bytes, alignment, req_addr, exec);
3628 }
3629
3630 if (addr != NULL) {
3631 if (UseNUMAInterleaving) {
3632 numa_make_global(addr, bytes);
3633 }
3634
3635 // The memory is committed
3636 MemTracker::record_virtual_memory_reserve_and_commit((address)addr, bytes, CALLER_PC);
3637 }
3638
3639 return addr;
3640 }
3641
3642 bool os::Linux::release_memory_special_shm(char* base, size_t bytes) {
3643 // detaching the SHM segment will also delete it, see reserve_memory_special_shm()
3644 return shmdt(base) == 0;
3645 }
3646
3647 bool os::Linux::release_memory_special_huge_tlbfs(char* base, size_t bytes) {
3648 return pd_release_memory(base, bytes);
3649 }
3650
3651 bool os::release_memory_special(char* base, size_t bytes) {
3652 bool res;
3653 if (MemTracker::tracking_level() > NMT_minimal) {
3654 Tracker tkr = MemTracker::get_virtual_memory_release_tracker();
3655 res = os::Linux::release_memory_special_impl(base, bytes);
3656 if (res) {
3657 tkr.record((address)base, bytes);
3658 }
3659
3660 } else {
3661 res = os::Linux::release_memory_special_impl(base, bytes);
3662 }
3663 return res;
3664 }
3665
3666 bool os::Linux::release_memory_special_impl(char* base, size_t bytes) {
3667 assert(UseLargePages, "only for large pages");
3668 bool res;
3669
3670 if (UseSHM) {
3671 res = os::Linux::release_memory_special_shm(base, bytes);
3672 } else {
3673 assert(UseHugeTLBFS, "must be");
3674 res = os::Linux::release_memory_special_huge_tlbfs(base, bytes);
3675 }
3676 return res;
3677 }
3678
3679 size_t os::large_page_size() {
3680 return _large_page_size;
3681 }
3682
3683 // With SysV SHM the entire memory region must be allocated as shared
3684 // memory.
3685 // HugeTLBFS allows application to commit large page memory on demand.
3686 // However, when committing memory with HugeTLBFS fails, the region
3687 // that was supposed to be committed will lose the old reservation
3688 // and allow other threads to steal that memory region. Because of this
3689 // behavior we can't commit HugeTLBFS memory.
3690 bool os::can_commit_large_page_memory() {
3691 return UseTransparentHugePages;
3692 }
3693
3694 bool os::can_execute_large_page_memory() {
3695 return UseTransparentHugePages || UseHugeTLBFS;
3696 }
3697
3698 // Reserve memory at an arbitrary address, only if that area is
3699 // available (and not reserved for something else).
3700
3701 char* os::pd_attempt_reserve_memory_at(size_t bytes, char* requested_addr) {
3702 const int max_tries = 10;
3703 char* base[max_tries];
3704 size_t size[max_tries];
3705 const size_t gap = 0x000000;
3706
3707 // Assert only that the size is a multiple of the page size, since
3708 // that's all that mmap requires, and since that's all we really know
3709 // about at this low abstraction level. If we need higher alignment,
3710 // we can either pass an alignment to this method or verify alignment
3711 // in one of the methods further up the call chain. See bug 5044738.
3712 assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block");
3713
3714 // Repeatedly allocate blocks until the block is allocated at the
3715 // right spot. Give up after max_tries. Note that reserve_memory() will
3716 // automatically update _highest_vm_reserved_address if the call is
3717 // successful. The variable tracks the highest memory address every reserved
3718 // by JVM. It is used to detect heap-stack collision if running with
3719 // fixed-stack LinuxThreads. Because here we may attempt to reserve more
3720 // space than needed, it could confuse the collision detecting code. To
3721 // solve the problem, save current _highest_vm_reserved_address and
3722 // calculate the correct value before return.
3723 address old_highest = _highest_vm_reserved_address;
3724
3725 // Linux mmap allows caller to pass an address as hint; give it a try first,
3726 // if kernel honors the hint then we can return immediately.
3727 char * addr = anon_mmap(requested_addr, bytes, false);
3728 if (addr == requested_addr) {
3729 return requested_addr;
3730 }
3731
3732 if (addr != NULL) {
3733 // mmap() is successful but it fails to reserve at the requested address
3734 anon_munmap(addr, bytes);
3735 }
3736
3737 int i;
3738 for (i = 0; i < max_tries; ++i) {
3739 base[i] = reserve_memory(bytes);
3740
3741 if (base[i] != NULL) {
3742 // Is this the block we wanted?
3743 if (base[i] == requested_addr) {
3744 size[i] = bytes;
3745 break;
3746 }
3747
3748 // Does this overlap the block we wanted? Give back the overlapped
3749 // parts and try again.
3750
3751 size_t top_overlap = requested_addr + (bytes + gap) - base[i];
3752 if (top_overlap >= 0 && top_overlap < bytes) {
3753 unmap_memory(base[i], top_overlap);
3754 base[i] += top_overlap;
3755 size[i] = bytes - top_overlap;
3756 } else {
3757 size_t bottom_overlap = base[i] + bytes - requested_addr;
3758 if (bottom_overlap >= 0 && bottom_overlap < bytes) {
3759 unmap_memory(requested_addr, bottom_overlap);
3760 size[i] = bytes - bottom_overlap;
3761 } else {
3762 size[i] = bytes;
3763 }
3764 }
3765 }
3766 }
3767
3768 // Give back the unused reserved pieces.
3769
3770 for (int j = 0; j < i; ++j) {
3771 if (base[j] != NULL) {
3772 unmap_memory(base[j], size[j]);
3773 }
3774 }
3775
3776 if (i < max_tries) {
3777 _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes);
3778 return requested_addr;
3779 } else {
3780 _highest_vm_reserved_address = old_highest;
3781 return NULL;
3782 }
3783 }
3784
3785 size_t os::read(int fd, void *buf, unsigned int nBytes) {
3786 return ::read(fd, buf, nBytes);
3787 }
3788
3789 size_t os::read_at(int fd, void *buf, unsigned int nBytes, jlong offset) {
3790 return ::pread(fd, buf, nBytes, offset);
3791 }
3792
3793 // Short sleep, direct OS call.
3794 //
3795 // Note: certain versions of Linux CFS scheduler (since 2.6.23) do not guarantee
3796 // sched_yield(2) will actually give up the CPU:
3797 //
3798 // * Alone on this pariticular CPU, keeps running.
3799 // * Before the introduction of "skip_buddy" with "compat_yield" disabled
3800 // (pre 2.6.39).
3801 //
3802 // So calling this with 0 is an alternative.
3803 //
3804 void os::naked_short_sleep(jlong ms) {
3805 struct timespec req;
3806
3807 assert(ms < 1000, "Un-interruptable sleep, short time use only");
3808 req.tv_sec = 0;
3809 if (ms > 0) {
3810 req.tv_nsec = (ms % 1000) * 1000000;
3811 } else {
3812 req.tv_nsec = 1;
3813 }
3814
3815 nanosleep(&req, NULL);
3816
3817 return;
3818 }
3819
3820 // Sleep forever; naked call to OS-specific sleep; use with CAUTION
3821 void os::infinite_sleep() {
3822 while (true) { // sleep forever ...
3823 ::sleep(100); // ... 100 seconds at a time
3824 }
3825 }
3826
3827 // Used to convert frequent JVM_Yield() to nops
3828 bool os::dont_yield() {
3829 return DontYieldALot;
3830 }
3831
3832 void os::naked_yield() {
3833 sched_yield();
3834 }
3835
3836 ////////////////////////////////////////////////////////////////////////////////
3837 // thread priority support
3838
3839 // Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER
3840 // only supports dynamic priority, static priority must be zero. For real-time
3841 // applications, Linux supports SCHED_RR which allows static priority (1-99).
3842 // However, for large multi-threaded applications, SCHED_RR is not only slower
3843 // than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out
3844 // of 5 runs - Sep 2005).
3845 //
3846 // The following code actually changes the niceness of kernel-thread/LWP. It
3847 // has an assumption that setpriority() only modifies one kernel-thread/LWP,
3848 // not the entire user process, and user level threads are 1:1 mapped to kernel
3849 // threads. It has always been the case, but could change in the future. For
3850 // this reason, the code should not be used as default (ThreadPriorityPolicy=0).
3851 // It is only used when ThreadPriorityPolicy=1 and requires root privilege.
3852
3853 int os::java_to_os_priority[CriticalPriority + 1] = {
3854 19, // 0 Entry should never be used
3855
3856 4, // 1 MinPriority
3857 3, // 2
3858 2, // 3
3859
3860 1, // 4
3861 0, // 5 NormPriority
3862 -1, // 6
3863
3864 -2, // 7
3865 -3, // 8
3866 -4, // 9 NearMaxPriority
3867
3868 -5, // 10 MaxPriority
3869
3870 -5 // 11 CriticalPriority
3871 };
3872
3873 static int prio_init() {
3874 if (ThreadPriorityPolicy == 1) {
3875 // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1
3876 // if effective uid is not root. Perhaps, a more elegant way of doing
3877 // this is to test CAP_SYS_NICE capability, but that will require libcap.so
3878 if (geteuid() != 0) {
3879 if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) {
3880 warning("-XX:ThreadPriorityPolicy requires root privilege on Linux");
3881 }
3882 ThreadPriorityPolicy = 0;
3883 }
3884 }
3885 if (UseCriticalJavaThreadPriority) {
3886 os::java_to_os_priority[MaxPriority] = os::java_to_os_priority[CriticalPriority];
3887 }
3888 return 0;
3889 }
3890
3891 OSReturn os::set_native_priority(Thread* thread, int newpri) {
3892 if (!UseThreadPriorities || ThreadPriorityPolicy == 0) return OS_OK;
3893
3894 int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri);
3895 return (ret == 0) ? OS_OK : OS_ERR;
3896 }
3897
3898 OSReturn os::get_native_priority(const Thread* const thread,
3899 int *priority_ptr) {
3900 if (!UseThreadPriorities || ThreadPriorityPolicy == 0) {
3901 *priority_ptr = java_to_os_priority[NormPriority];
3902 return OS_OK;
3903 }
3904
3905 errno = 0;
3906 *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id());
3907 return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR);
3908 }
3909
3910 // Hint to the underlying OS that a task switch would not be good.
3911 // Void return because it's a hint and can fail.
3912 void os::hint_no_preempt() {}
3913
3914 ////////////////////////////////////////////////////////////////////////////////
3915 // suspend/resume support
3916
3917 // the low-level signal-based suspend/resume support is a remnant from the
3918 // old VM-suspension that used to be for java-suspension, safepoints etc,
3919 // within hotspot. Now there is a single use-case for this:
3920 // - calling get_thread_pc() on the VMThread by the flat-profiler task
3921 // that runs in the watcher thread.
3922 // The remaining code is greatly simplified from the more general suspension
3923 // code that used to be used.
3924 //
3925 // The protocol is quite simple:
3926 // - suspend:
3927 // - sends a signal to the target thread
3928 // - polls the suspend state of the osthread using a yield loop
3929 // - target thread signal handler (SR_handler) sets suspend state
3930 // and blocks in sigsuspend until continued
3931 // - resume:
3932 // - sets target osthread state to continue
3933 // - sends signal to end the sigsuspend loop in the SR_handler
3934 //
3935 // Note that the SR_lock plays no role in this suspend/resume protocol.
3936
3937 static void resume_clear_context(OSThread *osthread) {
3938 osthread->set_ucontext(NULL);
3939 osthread->set_siginfo(NULL);
3940 }
3941
3942 static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo,
3943 ucontext_t* context) {
3944 osthread->set_ucontext(context);
3945 osthread->set_siginfo(siginfo);
3946 }
3947
3948 // Handler function invoked when a thread's execution is suspended or
3949 // resumed. We have to be careful that only async-safe functions are
3950 // called here (Note: most pthread functions are not async safe and
3951 // should be avoided.)
3952 //
3953 // Note: sigwait() is a more natural fit than sigsuspend() from an
3954 // interface point of view, but sigwait() prevents the signal hander
3955 // from being run. libpthread would get very confused by not having
3956 // its signal handlers run and prevents sigwait()'s use with the
3957 // mutex granting granting signal.
3958 //
3959 // Currently only ever called on the VMThread and JavaThreads (PC sampling)
3960 //
3961 static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) {
3962 // Save and restore errno to avoid confusing native code with EINTR
3963 // after sigsuspend.
3964 int old_errno = errno;
3965
3966 Thread* thread = Thread::current();
3967 OSThread* osthread = thread->osthread();
3968 assert(thread->is_VM_thread() || thread->is_Java_thread(), "Must be VMThread or JavaThread");
3969
3970 os::SuspendResume::State current = osthread->sr.state();
3971 if (current == os::SuspendResume::SR_SUSPEND_REQUEST) {
3972 suspend_save_context(osthread, siginfo, context);
3973
3974 // attempt to switch the state, we assume we had a SUSPEND_REQUEST
3975 os::SuspendResume::State state = osthread->sr.suspended();
3976 if (state == os::SuspendResume::SR_SUSPENDED) {
3977 sigset_t suspend_set; // signals for sigsuspend()
3978
3979 // get current set of blocked signals and unblock resume signal
3980 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set);
3981 sigdelset(&suspend_set, SR_signum);
3982
3983 sr_semaphore.signal();
3984 // wait here until we are resumed
3985 while (1) {
3986 sigsuspend(&suspend_set);
3987
3988 os::SuspendResume::State result = osthread->sr.running();
3989 if (result == os::SuspendResume::SR_RUNNING) {
3990 sr_semaphore.signal();
3991 break;
3992 }
3993 }
3994
3995 } else if (state == os::SuspendResume::SR_RUNNING) {
3996 // request was cancelled, continue
3997 } else {
3998 ShouldNotReachHere();
3999 }
4000
4001 resume_clear_context(osthread);
4002 } else if (current == os::SuspendResume::SR_RUNNING) {
4003 // request was cancelled, continue
4004 } else if (current == os::SuspendResume::SR_WAKEUP_REQUEST) {
4005 // ignore
4006 } else {
4007 // ignore
4008 }
4009
4010 errno = old_errno;
4011 }
4012
4013
4014 static int SR_initialize() {
4015 struct sigaction act;
4016 char *s;
4017 // Get signal number to use for suspend/resume
4018 if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) {
4019 int sig = ::strtol(s, 0, 10);
4020 if (sig > 0 || sig < _NSIG) {
4021 SR_signum = sig;
4022 }
4023 }
4024
4025 assert(SR_signum > SIGSEGV && SR_signum > SIGBUS,
4026 "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769");
4027
4028 sigemptyset(&SR_sigset);
4029 sigaddset(&SR_sigset, SR_signum);
4030
4031 // Set up signal handler for suspend/resume
4032 act.sa_flags = SA_RESTART|SA_SIGINFO;
4033 act.sa_handler = (void (*)(int)) SR_handler;
4034
4035 // SR_signum is blocked by default.
4036 // 4528190 - We also need to block pthread restart signal (32 on all
4037 // supported Linux platforms). Note that LinuxThreads need to block
4038 // this signal for all threads to work properly. So we don't have
4039 // to use hard-coded signal number when setting up the mask.
4040 pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask);
4041
4042 if (sigaction(SR_signum, &act, 0) == -1) {
4043 return -1;
4044 }
4045
4046 // Save signal flag
4047 os::Linux::set_our_sigflags(SR_signum, act.sa_flags);
4048 return 0;
4049 }
4050
4051 static int sr_notify(OSThread* osthread) {
4052 int status = pthread_kill(osthread->pthread_id(), SR_signum);
4053 assert_status(status == 0, status, "pthread_kill");
4054 return status;
4055 }
4056
4057 // "Randomly" selected value for how long we want to spin
4058 // before bailing out on suspending a thread, also how often
4059 // we send a signal to a thread we want to resume
4060 static const int RANDOMLY_LARGE_INTEGER = 1000000;
4061 static const int RANDOMLY_LARGE_INTEGER2 = 100;
4062
4063 // returns true on success and false on error - really an error is fatal
4064 // but this seems the normal response to library errors
4065 static bool do_suspend(OSThread* osthread) {
4066 assert(osthread->sr.is_running(), "thread should be running");
4067 assert(!sr_semaphore.trywait(), "semaphore has invalid state");
4068
4069 // mark as suspended and send signal
4070 if (osthread->sr.request_suspend() != os::SuspendResume::SR_SUSPEND_REQUEST) {
4071 // failed to switch, state wasn't running?
4072 ShouldNotReachHere();
4073 return false;
4074 }
4075
4076 if (sr_notify(osthread) != 0) {
4077 ShouldNotReachHere();
4078 }
4079
4080 // managed to send the signal and switch to SUSPEND_REQUEST, now wait for SUSPENDED
4081 while (true) {
4082 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) {
4083 break;
4084 } else {
4085 // timeout
4086 os::SuspendResume::State cancelled = osthread->sr.cancel_suspend();
4087 if (cancelled == os::SuspendResume::SR_RUNNING) {
4088 return false;
4089 } else if (cancelled == os::SuspendResume::SR_SUSPENDED) {
4090 // make sure that we consume the signal on the semaphore as well
4091 sr_semaphore.wait();
4092 break;
4093 } else {
4094 ShouldNotReachHere();
4095 return false;
4096 }
4097 }
4098 }
4099
4100 guarantee(osthread->sr.is_suspended(), "Must be suspended");
4101 return true;
4102 }
4103
4104 static void do_resume(OSThread* osthread) {
4105 assert(osthread->sr.is_suspended(), "thread should be suspended");
4106 assert(!sr_semaphore.trywait(), "invalid semaphore state");
4107
4108 if (osthread->sr.request_wakeup() != os::SuspendResume::SR_WAKEUP_REQUEST) {
4109 // failed to switch to WAKEUP_REQUEST
4110 ShouldNotReachHere();
4111 return;
4112 }
4113
4114 while (true) {
4115 if (sr_notify(osthread) == 0) {
4116 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) {
4117 if (osthread->sr.is_running()) {
4118 return;
4119 }
4120 }
4121 } else {
4122 ShouldNotReachHere();
4123 }
4124 }
4125
4126 guarantee(osthread->sr.is_running(), "Must be running!");
4127 }
4128
4129 ///////////////////////////////////////////////////////////////////////////////////
4130 // signal handling (except suspend/resume)
4131
4132 // This routine may be used by user applications as a "hook" to catch signals.
4133 // The user-defined signal handler must pass unrecognized signals to this
4134 // routine, and if it returns true (non-zero), then the signal handler must
4135 // return immediately. If the flag "abort_if_unrecognized" is true, then this
4136 // routine will never retun false (zero), but instead will execute a VM panic
4137 // routine kill the process.
4138 //
4139 // If this routine returns false, it is OK to call it again. This allows
4140 // the user-defined signal handler to perform checks either before or after
4141 // the VM performs its own checks. Naturally, the user code would be making
4142 // a serious error if it tried to handle an exception (such as a null check
4143 // or breakpoint) that the VM was generating for its own correct operation.
4144 //
4145 // This routine may recognize any of the following kinds of signals:
4146 // SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1.
4147 // It should be consulted by handlers for any of those signals.
4148 //
4149 // The caller of this routine must pass in the three arguments supplied
4150 // to the function referred to in the "sa_sigaction" (not the "sa_handler")
4151 // field of the structure passed to sigaction(). This routine assumes that
4152 // the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART.
4153 //
4154 // Note that the VM will print warnings if it detects conflicting signal
4155 // handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers".
4156 //
4157 extern "C" JNIEXPORT int JVM_handle_linux_signal(int signo,
4158 siginfo_t* siginfo,
4159 void* ucontext,
4160 int abort_if_unrecognized);
4161
4162 void signalHandler(int sig, siginfo_t* info, void* uc) {
4163 assert(info != NULL && uc != NULL, "it must be old kernel");
4164 int orig_errno = errno; // Preserve errno value over signal handler.
4165 JVM_handle_linux_signal(sig, info, uc, true);
4166 errno = orig_errno;
4167 }
4168
4169
4170 // This boolean allows users to forward their own non-matching signals
4171 // to JVM_handle_linux_signal, harmlessly.
4172 bool os::Linux::signal_handlers_are_installed = false;
4173
4174 // For signal-chaining
4175 struct sigaction os::Linux::sigact[MAXSIGNUM];
4176 unsigned int os::Linux::sigs = 0;
4177 bool os::Linux::libjsig_is_loaded = false;
4178 typedef struct sigaction *(*get_signal_t)(int);
4179 get_signal_t os::Linux::get_signal_action = NULL;
4180
4181 struct sigaction* os::Linux::get_chained_signal_action(int sig) {
4182 struct sigaction *actp = NULL;
4183
4184 if (libjsig_is_loaded) {
4185 // Retrieve the old signal handler from libjsig
4186 actp = (*get_signal_action)(sig);
4187 }
4188 if (actp == NULL) {
4189 // Retrieve the preinstalled signal handler from jvm
4190 actp = get_preinstalled_handler(sig);
4191 }
4192
4193 return actp;
4194 }
4195
4196 static bool call_chained_handler(struct sigaction *actp, int sig,
4197 siginfo_t *siginfo, void *context) {
4198 // Call the old signal handler
4199 if (actp->sa_handler == SIG_DFL) {
4200 // It's more reasonable to let jvm treat it as an unexpected exception
4201 // instead of taking the default action.
4202 return false;
4203 } else if (actp->sa_handler != SIG_IGN) {
4204 if ((actp->sa_flags & SA_NODEFER) == 0) {
4205 // automaticlly block the signal
4206 sigaddset(&(actp->sa_mask), sig);
4207 }
4208
4209 sa_handler_t hand;
4210 sa_sigaction_t sa;
4211 bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0;
4212 // retrieve the chained handler
4213 if (siginfo_flag_set) {
4214 sa = actp->sa_sigaction;
4215 } else {
4216 hand = actp->sa_handler;
4217 }
4218
4219 if ((actp->sa_flags & SA_RESETHAND) != 0) {
4220 actp->sa_handler = SIG_DFL;
4221 }
4222
4223 // try to honor the signal mask
4224 sigset_t oset;
4225 pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset);
4226
4227 // call into the chained handler
4228 if (siginfo_flag_set) {
4229 (*sa)(sig, siginfo, context);
4230 } else {
4231 (*hand)(sig);
4232 }
4233
4234 // restore the signal mask
4235 pthread_sigmask(SIG_SETMASK, &oset, 0);
4236 }
4237 // Tell jvm's signal handler the signal is taken care of.
4238 return true;
4239 }
4240
4241 bool os::Linux::chained_handler(int sig, siginfo_t* siginfo, void* context) {
4242 bool chained = false;
4243 // signal-chaining
4244 if (UseSignalChaining) {
4245 struct sigaction *actp = get_chained_signal_action(sig);
4246 if (actp != NULL) {
4247 chained = call_chained_handler(actp, sig, siginfo, context);
4248 }
4249 }
4250 return chained;
4251 }
4252
4253 struct sigaction* os::Linux::get_preinstalled_handler(int sig) {
4254 if ((((unsigned int)1 << sig) & sigs) != 0) {
4255 return &sigact[sig];
4256 }
4257 return NULL;
4258 }
4259
4260 void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) {
4261 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4262 sigact[sig] = oldAct;
4263 sigs |= (unsigned int)1 << sig;
4264 }
4265
4266 // for diagnostic
4267 int os::Linux::sigflags[MAXSIGNUM];
4268
4269 int os::Linux::get_our_sigflags(int sig) {
4270 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4271 return sigflags[sig];
4272 }
4273
4274 void os::Linux::set_our_sigflags(int sig, int flags) {
4275 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4276 sigflags[sig] = flags;
4277 }
4278
4279 void os::Linux::set_signal_handler(int sig, bool set_installed) {
4280 // Check for overwrite.
4281 struct sigaction oldAct;
4282 sigaction(sig, (struct sigaction*)NULL, &oldAct);
4283
4284 void* oldhand = oldAct.sa_sigaction
4285 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction)
4286 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler);
4287 if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) &&
4288 oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) &&
4289 oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) {
4290 if (AllowUserSignalHandlers || !set_installed) {
4291 // Do not overwrite; user takes responsibility to forward to us.
4292 return;
4293 } else if (UseSignalChaining) {
4294 // save the old handler in jvm
4295 save_preinstalled_handler(sig, oldAct);
4296 // libjsig also interposes the sigaction() call below and saves the
4297 // old sigaction on it own.
4298 } else {
4299 fatal(err_msg("Encountered unexpected pre-existing sigaction handler "
4300 "%#lx for signal %d.", (long)oldhand, sig));
4301 }
4302 }
4303
4304 struct sigaction sigAct;
4305 sigfillset(&(sigAct.sa_mask));
4306 sigAct.sa_handler = SIG_DFL;
4307 if (!set_installed) {
4308 sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
4309 } else {
4310 sigAct.sa_sigaction = signalHandler;
4311 sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
4312 }
4313 // Save flags, which are set by ours
4314 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4315 sigflags[sig] = sigAct.sa_flags;
4316
4317 int ret = sigaction(sig, &sigAct, &oldAct);
4318 assert(ret == 0, "check");
4319
4320 void* oldhand2 = oldAct.sa_sigaction
4321 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction)
4322 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler);
4323 assert(oldhand2 == oldhand, "no concurrent signal handler installation");
4324 }
4325
4326 // install signal handlers for signals that HotSpot needs to
4327 // handle in order to support Java-level exception handling.
4328
4329 void os::Linux::install_signal_handlers() {
4330 if (!signal_handlers_are_installed) {
4331 signal_handlers_are_installed = true;
4332
4333 // signal-chaining
4334 typedef void (*signal_setting_t)();
4335 signal_setting_t begin_signal_setting = NULL;
4336 signal_setting_t end_signal_setting = NULL;
4337 begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
4338 dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting"));
4339 if (begin_signal_setting != NULL) {
4340 end_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
4341 dlsym(RTLD_DEFAULT, "JVM_end_signal_setting"));
4342 get_signal_action = CAST_TO_FN_PTR(get_signal_t,
4343 dlsym(RTLD_DEFAULT, "JVM_get_signal_action"));
4344 libjsig_is_loaded = true;
4345 assert(UseSignalChaining, "should enable signal-chaining");
4346 }
4347 if (libjsig_is_loaded) {
4348 // Tell libjsig jvm is setting signal handlers
4349 (*begin_signal_setting)();
4350 }
4351
4352 set_signal_handler(SIGSEGV, true);
4353 set_signal_handler(SIGPIPE, true);
4354 set_signal_handler(SIGBUS, true);
4355 set_signal_handler(SIGILL, true);
4356 set_signal_handler(SIGFPE, true);
4357 #if defined(PPC64)
4358 set_signal_handler(SIGTRAP, true);
4359 #endif
4360 set_signal_handler(SIGXFSZ, true);
4361
4362 if (libjsig_is_loaded) {
4363 // Tell libjsig jvm finishes setting signal handlers
4364 (*end_signal_setting)();
4365 }
4366
4367 // We don't activate signal checker if libjsig is in place, we trust ourselves
4368 // and if UserSignalHandler is installed all bets are off.
4369 // Log that signal checking is off only if -verbose:jni is specified.
4370 if (CheckJNICalls) {
4371 if (libjsig_is_loaded) {
4372 if (PrintJNIResolving) {
4373 tty->print_cr("Info: libjsig is activated, all active signal checking is disabled");
4374 }
4375 check_signals = false;
4376 }
4377 if (AllowUserSignalHandlers) {
4378 if (PrintJNIResolving) {
4379 tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled");
4380 }
4381 check_signals = false;
4382 }
4383 }
4384 }
4385 }
4386
4387 // This is the fastest way to get thread cpu time on Linux.
4388 // Returns cpu time (user+sys) for any thread, not only for current.
4389 // POSIX compliant clocks are implemented in the kernels 2.6.16+.
4390 // It might work on 2.6.10+ with a special kernel/glibc patch.
4391 // For reference, please, see IEEE Std 1003.1-2004:
4392 // http://www.unix.org/single_unix_specification
4393
4394 jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) {
4395 struct timespec tp;
4396 int rc = os::Linux::clock_gettime(clockid, &tp);
4397 assert(rc == 0, "clock_gettime is expected to return 0 code");
4398
4399 return (tp.tv_sec * NANOSECS_PER_SEC) + tp.tv_nsec;
4400 }
4401
4402 /////
4403 // glibc on Linux platform uses non-documented flag
4404 // to indicate, that some special sort of signal
4405 // trampoline is used.
4406 // We will never set this flag, and we should
4407 // ignore this flag in our diagnostic
4408 #ifdef SIGNIFICANT_SIGNAL_MASK
4409 #undef SIGNIFICANT_SIGNAL_MASK
4410 #endif
4411 #define SIGNIFICANT_SIGNAL_MASK (~0x04000000)
4412
4413 static const char* get_signal_handler_name(address handler,
4414 char* buf, int buflen) {
4415 int offset;
4416 bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset);
4417 if (found) {
4418 // skip directory names
4419 const char *p1, *p2;
4420 p1 = buf;
4421 size_t len = strlen(os::file_separator());
4422 while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len;
4423 jio_snprintf(buf, buflen, "%s+0x%x", p1, offset);
4424 } else {
4425 jio_snprintf(buf, buflen, PTR_FORMAT, handler);
4426 }
4427 return buf;
4428 }
4429
4430 static void print_signal_handler(outputStream* st, int sig,
4431 char* buf, size_t buflen) {
4432 struct sigaction sa;
4433
4434 sigaction(sig, NULL, &sa);
4435
4436 // See comment for SIGNIFICANT_SIGNAL_MASK define
4437 sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
4438
4439 st->print("%s: ", os::exception_name(sig, buf, buflen));
4440
4441 address handler = (sa.sa_flags & SA_SIGINFO)
4442 ? CAST_FROM_FN_PTR(address, sa.sa_sigaction)
4443 : CAST_FROM_FN_PTR(address, sa.sa_handler);
4444
4445 if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) {
4446 st->print("SIG_DFL");
4447 } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) {
4448 st->print("SIG_IGN");
4449 } else {
4450 st->print("[%s]", get_signal_handler_name(handler, buf, buflen));
4451 }
4452
4453 st->print(", sa_mask[0]=");
4454 os::Posix::print_signal_set_short(st, &sa.sa_mask);
4455
4456 address rh = VMError::get_resetted_sighandler(sig);
4457 // May be, handler was resetted by VMError?
4458 if (rh != NULL) {
4459 handler = rh;
4460 sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK;
4461 }
4462
4463 st->print(", sa_flags=");
4464 os::Posix::print_sa_flags(st, sa.sa_flags);
4465
4466 // Check: is it our handler?
4467 if (handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) ||
4468 handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) {
4469 // It is our signal handler
4470 // check for flags, reset system-used one!
4471 if ((int)sa.sa_flags != os::Linux::get_our_sigflags(sig)) {
4472 st->print(
4473 ", flags was changed from " PTR32_FORMAT ", consider using jsig library",
4474 os::Linux::get_our_sigflags(sig));
4475 }
4476 }
4477 st->cr();
4478 }
4479
4480
4481 #define DO_SIGNAL_CHECK(sig) \
4482 do { \
4483 if (!sigismember(&check_signal_done, sig)) { \
4484 os::Linux::check_signal_handler(sig); \
4485 } \
4486 } while (0)
4487
4488 // This method is a periodic task to check for misbehaving JNI applications
4489 // under CheckJNI, we can add any periodic checks here
4490
4491 void os::run_periodic_checks() {
4492 if (check_signals == false) return;
4493
4494 // SEGV and BUS if overridden could potentially prevent
4495 // generation of hs*.log in the event of a crash, debugging
4496 // such a case can be very challenging, so we absolutely
4497 // check the following for a good measure:
4498 DO_SIGNAL_CHECK(SIGSEGV);
4499 DO_SIGNAL_CHECK(SIGILL);
4500 DO_SIGNAL_CHECK(SIGFPE);
4501 DO_SIGNAL_CHECK(SIGBUS);
4502 DO_SIGNAL_CHECK(SIGPIPE);
4503 DO_SIGNAL_CHECK(SIGXFSZ);
4504 #if defined(PPC64)
4505 DO_SIGNAL_CHECK(SIGTRAP);
4506 #endif
4507
4508 // ReduceSignalUsage allows the user to override these handlers
4509 // see comments at the very top and jvm_solaris.h
4510 if (!ReduceSignalUsage) {
4511 DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL);
4512 DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL);
4513 DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL);
4514 DO_SIGNAL_CHECK(BREAK_SIGNAL);
4515 }
4516
4517 DO_SIGNAL_CHECK(SR_signum);
4518 DO_SIGNAL_CHECK(INTERRUPT_SIGNAL);
4519 }
4520
4521 typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *);
4522
4523 static os_sigaction_t os_sigaction = NULL;
4524
4525 void os::Linux::check_signal_handler(int sig) {
4526 char buf[O_BUFLEN];
4527 address jvmHandler = NULL;
4528
4529
4530 struct sigaction act;
4531 if (os_sigaction == NULL) {
4532 // only trust the default sigaction, in case it has been interposed
4533 os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction");
4534 if (os_sigaction == NULL) return;
4535 }
4536
4537 os_sigaction(sig, (struct sigaction*)NULL, &act);
4538
4539
4540 act.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
4541
4542 address thisHandler = (act.sa_flags & SA_SIGINFO)
4543 ? CAST_FROM_FN_PTR(address, act.sa_sigaction)
4544 : CAST_FROM_FN_PTR(address, act.sa_handler);
4545
4546
4547 switch (sig) {
4548 case SIGSEGV:
4549 case SIGBUS:
4550 case SIGFPE:
4551 case SIGPIPE:
4552 case SIGILL:
4553 case SIGXFSZ:
4554 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler);
4555 break;
4556
4557 case SHUTDOWN1_SIGNAL:
4558 case SHUTDOWN2_SIGNAL:
4559 case SHUTDOWN3_SIGNAL:
4560 case BREAK_SIGNAL:
4561 jvmHandler = (address)user_handler();
4562 break;
4563
4564 case INTERRUPT_SIGNAL:
4565 jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL);
4566 break;
4567
4568 default:
4569 if (sig == SR_signum) {
4570 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler);
4571 } else {
4572 return;
4573 }
4574 break;
4575 }
4576
4577 if (thisHandler != jvmHandler) {
4578 tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN));
4579 tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN));
4580 tty->print_cr(" found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN));
4581 // No need to check this sig any longer
4582 sigaddset(&check_signal_done, sig);
4583 // Running under non-interactive shell, SHUTDOWN2_SIGNAL will be reassigned SIG_IGN
4584 if (sig == SHUTDOWN2_SIGNAL && !isatty(fileno(stdin))) {
4585 tty->print_cr("Running in non-interactive shell, %s handler is replaced by shell",
4586 exception_name(sig, buf, O_BUFLEN));
4587 }
4588 } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) {
4589 tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN));
4590 tty->print("expected:" PTR32_FORMAT, os::Linux::get_our_sigflags(sig));
4591 tty->print_cr(" found:" PTR32_FORMAT, act.sa_flags);
4592 // No need to check this sig any longer
4593 sigaddset(&check_signal_done, sig);
4594 }
4595
4596 // Dump all the signal
4597 if (sigismember(&check_signal_done, sig)) {
4598 print_signal_handlers(tty, buf, O_BUFLEN);
4599 }
4600 }
4601
4602 extern void report_error(char* file_name, int line_no, char* title,
4603 char* format, ...);
4604
4605 extern bool signal_name(int signo, char* buf, size_t len);
4606
4607 const char* os::exception_name(int exception_code, char* buf, size_t size) {
4608 if (0 < exception_code && exception_code <= SIGRTMAX) {
4609 // signal
4610 if (!signal_name(exception_code, buf, size)) {
4611 jio_snprintf(buf, size, "SIG%d", exception_code);
4612 }
4613 return buf;
4614 } else {
4615 return NULL;
4616 }
4617 }
4618
4619 // this is called _before_ the most of global arguments have been parsed
4620 void os::init(void) {
4621 char dummy; // used to get a guess on initial stack address
4622 // first_hrtime = gethrtime();
4623
4624 // With LinuxThreads the JavaMain thread pid (primordial thread)
4625 // is different than the pid of the java launcher thread.
4626 // So, on Linux, the launcher thread pid is passed to the VM
4627 // via the sun.java.launcher.pid property.
4628 // Use this property instead of getpid() if it was correctly passed.
4629 // See bug 6351349.
4630 pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid();
4631
4632 _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid();
4633
4634 clock_tics_per_sec = sysconf(_SC_CLK_TCK);
4635
4636 init_random(1234567);
4637
4638 ThreadCritical::initialize();
4639
4640 Linux::set_page_size(sysconf(_SC_PAGESIZE));
4641 if (Linux::page_size() == -1) {
4642 fatal(err_msg("os_linux.cpp: os::init: sysconf failed (%s)",
4643 strerror(errno)));
4644 }
4645 init_page_sizes((size_t) Linux::page_size());
4646
4647 Linux::initialize_system_info();
4648
4649 // main_thread points to the aboriginal thread
4650 Linux::_main_thread = pthread_self();
4651
4652 Linux::clock_init();
4653 initial_time_count = javaTimeNanos();
4654
4655 // pthread_condattr initialization for monotonic clock
4656 int status;
4657 pthread_condattr_t* _condattr = os::Linux::condAttr();
4658 if ((status = pthread_condattr_init(_condattr)) != 0) {
4659 fatal(err_msg("pthread_condattr_init: %s", strerror(status)));
4660 }
4661 // Only set the clock if CLOCK_MONOTONIC is available
4662 if (os::supports_monotonic_clock()) {
4663 if ((status = pthread_condattr_setclock(_condattr, CLOCK_MONOTONIC)) != 0) {
4664 if (status == EINVAL) {
4665 warning("Unable to use monotonic clock with relative timed-waits" \
4666 " - changes to the time-of-day clock may have adverse affects");
4667 } else {
4668 fatal(err_msg("pthread_condattr_setclock: %s", strerror(status)));
4669 }
4670 }
4671 }
4672 // else it defaults to CLOCK_REALTIME
4673
4674 pthread_mutex_init(&dl_mutex, NULL);
4675
4676 // If the pagesize of the VM is greater than 8K determine the appropriate
4677 // number of initial guard pages. The user can change this with the
4678 // command line arguments, if needed.
4679 if (vm_page_size() > (int)Linux::vm_default_page_size()) {
4680 StackYellowPages = 1;
4681 StackRedPages = 1;
4682 StackShadowPages = round_to((StackShadowPages*Linux::vm_default_page_size()), vm_page_size()) / vm_page_size();
4683 }
4684
4685 // retrieve entry point for pthread_setname_np
4686 Linux::_pthread_setname_np =
4687 (int(*)(pthread_t, const char*))dlsym(RTLD_DEFAULT, "pthread_setname_np");
4688
4689 }
4690
4691 // To install functions for atexit system call
4692 extern "C" {
4693 static void perfMemory_exit_helper() {
4694 perfMemory_exit();
4695 }
4696 }
4697
4698 // this is called _after_ the global arguments have been parsed
4699 jint os::init_2(void) {
4700 Linux::fast_thread_clock_init();
4701
4702 // Allocate a single page and mark it as readable for safepoint polling
4703 address polling_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
4704 guarantee(polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page");
4705
4706 os::set_polling_page(polling_page);
4707
4708 #ifndef PRODUCT
4709 if (Verbose && PrintMiscellaneous) {
4710 tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n",
4711 (intptr_t)polling_page);
4712 }
4713 #endif
4714
4715 if (!UseMembar) {
4716 address mem_serialize_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
4717 guarantee(mem_serialize_page != MAP_FAILED, "mmap Failed for memory serialize page");
4718 os::set_memory_serialize_page(mem_serialize_page);
4719
4720 #ifndef PRODUCT
4721 if (Verbose && PrintMiscellaneous) {
4722 tty->print("[Memory Serialize Page address: " INTPTR_FORMAT "]\n",
4723 (intptr_t)mem_serialize_page);
4724 }
4725 #endif
4726 }
4727
4728 // initialize suspend/resume support - must do this before signal_sets_init()
4729 if (SR_initialize() != 0) {
4730 perror("SR_initialize failed");
4731 return JNI_ERR;
4732 }
4733
4734 Linux::signal_sets_init();
4735 Linux::install_signal_handlers();
4736
4737 // Check minimum allowable stack size for thread creation and to initialize
4738 // the java system classes, including StackOverflowError - depends on page
4739 // size. Add a page for compiler2 recursion in main thread.
4740 // Add in 2*BytesPerWord times page size to account for VM stack during
4741 // class initialization depending on 32 or 64 bit VM.
4742 os::Linux::min_stack_allowed = MAX2(os::Linux::min_stack_allowed,
4743 (size_t)(StackYellowPages+StackRedPages+StackShadowPages) * Linux::page_size() +
4744 (2*BytesPerWord COMPILER2_PRESENT(+1)) * Linux::vm_default_page_size());
4745
4746 size_t threadStackSizeInBytes = ThreadStackSize * K;
4747 if (threadStackSizeInBytes != 0 &&
4748 threadStackSizeInBytes < os::Linux::min_stack_allowed) {
4749 tty->print_cr("\nThe stack size specified is too small, "
4750 "Specify at least %dk",
4751 os::Linux::min_stack_allowed/ K);
4752 return JNI_ERR;
4753 }
4754
4755 // Make the stack size a multiple of the page size so that
4756 // the yellow/red zones can be guarded.
4757 JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes,
4758 vm_page_size()));
4759
4760 Linux::capture_initial_stack(JavaThread::stack_size_at_create());
4761
4762 #if defined(IA32)
4763 workaround_expand_exec_shield_cs_limit();
4764 #endif
4765
4766 Linux::libpthread_init();
4767 if (PrintMiscellaneous && (Verbose || WizardMode)) {
4768 tty->print_cr("[HotSpot is running with %s, %s(%s)]\n",
4769 Linux::glibc_version(), Linux::libpthread_version(),
4770 Linux::is_floating_stack() ? "floating stack" : "fixed stack");
4771 }
4772
4773 if (UseNUMA) {
4774 if (!Linux::libnuma_init()) {
4775 UseNUMA = false;
4776 } else {
4777 if ((Linux::numa_max_node() < 1)) {
4778 // There's only one node(they start from 0), disable NUMA.
4779 UseNUMA = false;
4780 }
4781 }
4782 // With SHM and HugeTLBFS large pages we cannot uncommit a page, so there's no way
4783 // we can make the adaptive lgrp chunk resizing work. If the user specified
4784 // both UseNUMA and UseLargePages (or UseSHM/UseHugeTLBFS) on the command line - warn and
4785 // disable adaptive resizing.
4786 if (UseNUMA && UseLargePages && !can_commit_large_page_memory()) {
4787 if (FLAG_IS_DEFAULT(UseNUMA)) {
4788 UseNUMA = false;
4789 } else {
4790 if (FLAG_IS_DEFAULT(UseLargePages) &&
4791 FLAG_IS_DEFAULT(UseSHM) &&
4792 FLAG_IS_DEFAULT(UseHugeTLBFS)) {
4793 UseLargePages = false;
4794 } else {
4795 warning("UseNUMA is not fully compatible with SHM/HugeTLBFS large pages, disabling adaptive resizing");
4796 UseAdaptiveSizePolicy = false;
4797 UseAdaptiveNUMAChunkSizing = false;
4798 }
4799 }
4800 }
4801 if (!UseNUMA && ForceNUMA) {
4802 UseNUMA = true;
4803 }
4804 }
4805
4806 if (MaxFDLimit) {
4807 // set the number of file descriptors to max. print out error
4808 // if getrlimit/setrlimit fails but continue regardless.
4809 struct rlimit nbr_files;
4810 int status = getrlimit(RLIMIT_NOFILE, &nbr_files);
4811 if (status != 0) {
4812 if (PrintMiscellaneous && (Verbose || WizardMode)) {
4813 perror("os::init_2 getrlimit failed");
4814 }
4815 } else {
4816 nbr_files.rlim_cur = nbr_files.rlim_max;
4817 status = setrlimit(RLIMIT_NOFILE, &nbr_files);
4818 if (status != 0) {
4819 if (PrintMiscellaneous && (Verbose || WizardMode)) {
4820 perror("os::init_2 setrlimit failed");
4821 }
4822 }
4823 }
4824 }
4825
4826 // Initialize lock used to serialize thread creation (see os::create_thread)
4827 Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false));
4828
4829 // at-exit methods are called in the reverse order of their registration.
4830 // atexit functions are called on return from main or as a result of a
4831 // call to exit(3C). There can be only 32 of these functions registered
4832 // and atexit() does not set errno.
4833
4834 if (PerfAllowAtExitRegistration) {
4835 // only register atexit functions if PerfAllowAtExitRegistration is set.
4836 // atexit functions can be delayed until process exit time, which
4837 // can be problematic for embedded VM situations. Embedded VMs should
4838 // call DestroyJavaVM() to assure that VM resources are released.
4839
4840 // note: perfMemory_exit_helper atexit function may be removed in
4841 // the future if the appropriate cleanup code can be added to the
4842 // VM_Exit VMOperation's doit method.
4843 if (atexit(perfMemory_exit_helper) != 0) {
4844 warning("os::init_2 atexit(perfMemory_exit_helper) failed");
4845 }
4846 }
4847
4848 // initialize thread priority policy
4849 prio_init();
4850
4851 return JNI_OK;
4852 }
4853
4854 // Mark the polling page as unreadable
4855 void os::make_polling_page_unreadable(void) {
4856 if (!guard_memory((char*)_polling_page, Linux::page_size())) {
4857 fatal("Could not disable polling page");
4858 }
4859 }
4860
4861 // Mark the polling page as readable
4862 void os::make_polling_page_readable(void) {
4863 if (!linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) {
4864 fatal("Could not enable polling page");
4865 }
4866 }
4867
4868 int os::active_processor_count() {
4869 // Linux doesn't yet have a (official) notion of processor sets,
4870 // so just return the number of online processors.
4871 int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN);
4872 assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check");
4873 return online_cpus;
4874 }
4875
4876 void os::set_native_thread_name(const char *name) {
4877 if (Linux::_pthread_setname_np) {
4878 char buf [16]; // according to glibc manpage, 16 chars incl. '/0'
4879 snprintf(buf, sizeof(buf), "%s", name);
4880 buf[sizeof(buf) - 1] = '\0';
4881 const int rc = Linux::_pthread_setname_np(pthread_self(), buf);
4882 // ERANGE should not happen; all other errors should just be ignored.
4883 assert(rc != ERANGE, "pthread_setname_np failed");
4884 }
4885 }
4886
4887 bool os::distribute_processes(uint length, uint* distribution) {
4888 // Not yet implemented.
4889 return false;
4890 }
4891
4892 bool os::bind_to_processor(uint processor_id) {
4893 // Not yet implemented.
4894 return false;
4895 }
4896
4897 ///
4898
4899 void os::SuspendedThreadTask::internal_do_task() {
4900 if (do_suspend(_thread->osthread())) {
4901 SuspendedThreadTaskContext context(_thread, _thread->osthread()->ucontext());
4902 do_task(context);
4903 do_resume(_thread->osthread());
4904 }
4905 }
4906
4907 class PcFetcher : public os::SuspendedThreadTask {
4908 public:
4909 PcFetcher(Thread* thread) : os::SuspendedThreadTask(thread) {}
4910 ExtendedPC result();
4911 protected:
4912 void do_task(const os::SuspendedThreadTaskContext& context);
4913 private:
4914 ExtendedPC _epc;
4915 };
4916
4917 ExtendedPC PcFetcher::result() {
4918 guarantee(is_done(), "task is not done yet.");
4919 return _epc;
4920 }
4921
4922 void PcFetcher::do_task(const os::SuspendedThreadTaskContext& context) {
4923 Thread* thread = context.thread();
4924 OSThread* osthread = thread->osthread();
4925 if (osthread->ucontext() != NULL) {
4926 _epc = os::Linux::ucontext_get_pc((ucontext_t *) context.ucontext());
4927 } else {
4928 // NULL context is unexpected, double-check this is the VMThread
4929 guarantee(thread->is_VM_thread(), "can only be called for VMThread");
4930 }
4931 }
4932
4933 // Suspends the target using the signal mechanism and then grabs the PC before
4934 // resuming the target. Used by the flat-profiler only
4935 ExtendedPC os::get_thread_pc(Thread* thread) {
4936 // Make sure that it is called by the watcher for the VMThread
4937 assert(Thread::current()->is_Watcher_thread(), "Must be watcher");
4938 assert(thread->is_VM_thread(), "Can only be called for VMThread");
4939
4940 PcFetcher fetcher(thread);
4941 fetcher.run();
4942 return fetcher.result();
4943 }
4944
4945 int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond,
4946 pthread_mutex_t *_mutex,
4947 const struct timespec *_abstime) {
4948 if (is_NPTL()) {
4949 return pthread_cond_timedwait(_cond, _mutex, _abstime);
4950 } else {
4951 // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control
4952 // word back to default 64bit precision if condvar is signaled. Java
4953 // wants 53bit precision. Save and restore current value.
4954 int fpu = get_fpu_control_word();
4955 int status = pthread_cond_timedwait(_cond, _mutex, _abstime);
4956 set_fpu_control_word(fpu);
4957 return status;
4958 }
4959 }
4960
4961 ////////////////////////////////////////////////////////////////////////////////
4962 // debug support
4963
4964 bool os::find(address addr, outputStream* st) {
4965 Dl_info dlinfo;
4966 memset(&dlinfo, 0, sizeof(dlinfo));
4967 if (dladdr(addr, &dlinfo) != 0) {
4968 st->print(PTR_FORMAT ": ", addr);
4969 if (dlinfo.dli_sname != NULL && dlinfo.dli_saddr != NULL) {
4970 st->print("%s+%#x", dlinfo.dli_sname,
4971 addr - (intptr_t)dlinfo.dli_saddr);
4972 } else if (dlinfo.dli_fbase != NULL) {
4973 st->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase);
4974 } else {
4975 st->print("<absolute address>");
4976 }
4977 if (dlinfo.dli_fname != NULL) {
4978 st->print(" in %s", dlinfo.dli_fname);
4979 }
4980 if (dlinfo.dli_fbase != NULL) {
4981 st->print(" at " PTR_FORMAT, dlinfo.dli_fbase);
4982 }
4983 st->cr();
4984
4985 if (Verbose) {
4986 // decode some bytes around the PC
4987 address begin = clamp_address_in_page(addr-40, addr, os::vm_page_size());
4988 address end = clamp_address_in_page(addr+40, addr, os::vm_page_size());
4989 address lowest = (address) dlinfo.dli_sname;
4990 if (!lowest) lowest = (address) dlinfo.dli_fbase;
4991 if (begin < lowest) begin = lowest;
4992 Dl_info dlinfo2;
4993 if (dladdr(end, &dlinfo2) != 0 && dlinfo2.dli_saddr != dlinfo.dli_saddr
4994 && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin) {
4995 end = (address) dlinfo2.dli_saddr;
4996 }
4997 Disassembler::decode(begin, end, st);
4998 }
4999 return true;
5000 }
5001 return false;
5002 }
5003
5004 ////////////////////////////////////////////////////////////////////////////////
5005 // misc
5006
5007 // This does not do anything on Linux. This is basically a hook for being
5008 // able to use structured exception handling (thread-local exception filters)
5009 // on, e.g., Win32.
5010 void
5011 os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method,
5012 JavaCallArguments* args, Thread* thread) {
5013 f(value, method, args, thread);
5014 }
5015
5016 void os::print_statistics() {
5017 }
5018
5019 int os::message_box(const char* title, const char* message) {
5020 int i;
5021 fdStream err(defaultStream::error_fd());
5022 for (i = 0; i < 78; i++) err.print_raw("=");
5023 err.cr();
5024 err.print_raw_cr(title);
5025 for (i = 0; i < 78; i++) err.print_raw("-");
5026 err.cr();
5027 err.print_raw_cr(message);
5028 for (i = 0; i < 78; i++) err.print_raw("=");
5029 err.cr();
5030
5031 char buf[16];
5032 // Prevent process from exiting upon "read error" without consuming all CPU
5033 while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); }
5034
5035 return buf[0] == 'y' || buf[0] == 'Y';
5036 }
5037
5038 int os::stat(const char *path, struct stat *sbuf) {
5039 char pathbuf[MAX_PATH];
5040 if (strlen(path) > MAX_PATH - 1) {
5041 errno = ENAMETOOLONG;
5042 return -1;
5043 }
5044 os::native_path(strcpy(pathbuf, path));
5045 return ::stat(pathbuf, sbuf);
5046 }
5047
5048 bool os::check_heap(bool force) {
5049 return true;
5050 }
5051
5052 // Is a (classpath) directory empty?
5053 bool os::dir_is_empty(const char* path) {
5054 DIR *dir = NULL;
5055 struct dirent *ptr;
5056
5057 dir = opendir(path);
5058 if (dir == NULL) return true;
5059
5060 // Scan the directory
5061 bool result = true;
5062 char buf[sizeof(struct dirent) + MAX_PATH];
5063 while (result && (ptr = ::readdir(dir)) != NULL) {
5064 if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) {
5065 result = false;
5066 }
5067 }
5068 closedir(dir);
5069 return result;
5070 }
5071
5072 // This code originates from JDK's sysOpen and open64_w
5073 // from src/solaris/hpi/src/system_md.c
5074
5075 int os::open(const char *path, int oflag, int mode) {
5076 if (strlen(path) > MAX_PATH - 1) {
5077 errno = ENAMETOOLONG;
5078 return -1;
5079 }
5080
5081 // All file descriptors that are opened in the Java process and not
5082 // specifically destined for a subprocess should have the close-on-exec
5083 // flag set. If we don't set it, then careless 3rd party native code
5084 // might fork and exec without closing all appropriate file descriptors
5085 // (e.g. as we do in closeDescriptors in UNIXProcess.c), and this in
5086 // turn might:
5087 //
5088 // - cause end-of-file to fail to be detected on some file
5089 // descriptors, resulting in mysterious hangs, or
5090 //
5091 // - might cause an fopen in the subprocess to fail on a system
5092 // suffering from bug 1085341.
5093 //
5094 // (Yes, the default setting of the close-on-exec flag is a Unix
5095 // design flaw)
5096 //
5097 // See:
5098 // 1085341: 32-bit stdio routines should support file descriptors >255
5099 // 4843136: (process) pipe file descriptor from Runtime.exec not being closed
5100 // 6339493: (process) Runtime.exec does not close all file descriptors on Solaris 9
5101 //
5102 // Modern Linux kernels (after 2.6.23 2007) support O_CLOEXEC with open().
5103 // O_CLOEXEC is preferable to using FD_CLOEXEC on an open file descriptor
5104 // because it saves a system call and removes a small window where the flag
5105 // is unset. On ancient Linux kernels the O_CLOEXEC flag will be ignored
5106 // and we fall back to using FD_CLOEXEC (see below).
5107 #ifdef O_CLOEXEC
5108 oflag |= O_CLOEXEC;
5109 #endif
5110
5111 int fd = ::open64(path, oflag, mode);
5112 if (fd == -1) return -1;
5113
5114 //If the open succeeded, the file might still be a directory
5115 {
5116 struct stat64 buf64;
5117 int ret = ::fstat64(fd, &buf64);
5118 int st_mode = buf64.st_mode;
5119
5120 if (ret != -1) {
5121 if ((st_mode & S_IFMT) == S_IFDIR) {
5122 errno = EISDIR;
5123 ::close(fd);
5124 return -1;
5125 }
5126 } else {
5127 ::close(fd);
5128 return -1;
5129 }
5130 }
5131
5132 #ifdef FD_CLOEXEC
5133 // Validate that the use of the O_CLOEXEC flag on open above worked.
5134 // With recent kernels, we will perform this check exactly once.
5135 static sig_atomic_t O_CLOEXEC_is_known_to_work = 0;
5136 if (!O_CLOEXEC_is_known_to_work) {
5137 int flags = ::fcntl(fd, F_GETFD);
5138 if (flags != -1) {
5139 if ((flags & FD_CLOEXEC) != 0)
5140 O_CLOEXEC_is_known_to_work = 1;
5141 else
5142 ::fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
5143 }
5144 }
5145 #endif
5146
5147 return fd;
5148 }
5149
5150
5151 // create binary file, rewriting existing file if required
5152 int os::create_binary_file(const char* path, bool rewrite_existing) {
5153 int oflags = O_WRONLY | O_CREAT;
5154 if (!rewrite_existing) {
5155 oflags |= O_EXCL;
5156 }
5157 return ::open64(path, oflags, S_IREAD | S_IWRITE);
5158 }
5159
5160 // return current position of file pointer
5161 jlong os::current_file_offset(int fd) {
5162 return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR);
5163 }
5164
5165 // move file pointer to the specified offset
5166 jlong os::seek_to_file_offset(int fd, jlong offset) {
5167 return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET);
5168 }
5169
5170 // This code originates from JDK's sysAvailable
5171 // from src/solaris/hpi/src/native_threads/src/sys_api_td.c
5172
5173 int os::available(int fd, jlong *bytes) {
5174 jlong cur, end;
5175 int mode;
5176 struct stat64 buf64;
5177
5178 if (::fstat64(fd, &buf64) >= 0) {
5179 mode = buf64.st_mode;
5180 if (S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) {
5181 // XXX: is the following call interruptible? If so, this might
5182 // need to go through the INTERRUPT_IO() wrapper as for other
5183 // blocking, interruptible calls in this file.
5184 int n;
5185 if (::ioctl(fd, FIONREAD, &n) >= 0) {
5186 *bytes = n;
5187 return 1;
5188 }
5189 }
5190 }
5191 if ((cur = ::lseek64(fd, 0L, SEEK_CUR)) == -1) {
5192 return 0;
5193 } else if ((end = ::lseek64(fd, 0L, SEEK_END)) == -1) {
5194 return 0;
5195 } else if (::lseek64(fd, cur, SEEK_SET) == -1) {
5196 return 0;
5197 }
5198 *bytes = end - cur;
5199 return 1;
5200 }
5201
5202 // Map a block of memory.
5203 char* os::pd_map_memory(int fd, const char* file_name, size_t file_offset,
5204 char *addr, size_t bytes, bool read_only,
5205 bool allow_exec) {
5206 int prot;
5207 int flags = MAP_PRIVATE;
5208
5209 if (read_only) {
5210 prot = PROT_READ;
5211 } else {
5212 prot = PROT_READ | PROT_WRITE;
5213 }
5214
5215 if (allow_exec) {
5216 prot |= PROT_EXEC;
5217 }
5218
5219 if (addr != NULL) {
5220 flags |= MAP_FIXED;
5221 }
5222
5223 char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags,
5224 fd, file_offset);
5225 if (mapped_address == MAP_FAILED) {
5226 return NULL;
5227 }
5228 return mapped_address;
5229 }
5230
5231
5232 // Remap a block of memory.
5233 char* os::pd_remap_memory(int fd, const char* file_name, size_t file_offset,
5234 char *addr, size_t bytes, bool read_only,
5235 bool allow_exec) {
5236 // same as map_memory() on this OS
5237 return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only,
5238 allow_exec);
5239 }
5240
5241
5242 // Unmap a block of memory.
5243 bool os::pd_unmap_memory(char* addr, size_t bytes) {
5244 return munmap(addr, bytes) == 0;
5245 }
5246
5247 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time);
5248
5249 static clockid_t thread_cpu_clockid(Thread* thread) {
5250 pthread_t tid = thread->osthread()->pthread_id();
5251 clockid_t clockid;
5252
5253 // Get thread clockid
5254 int rc = os::Linux::pthread_getcpuclockid(tid, &clockid);
5255 assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code");
5256 return clockid;
5257 }
5258
5259 // current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool)
5260 // are used by JVM M&M and JVMTI to get user+sys or user CPU time
5261 // of a thread.
5262 //
5263 // current_thread_cpu_time() and thread_cpu_time(Thread*) returns
5264 // the fast estimate available on the platform.
5265
5266 jlong os::current_thread_cpu_time() {
5267 if (os::Linux::supports_fast_thread_cpu_time()) {
5268 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
5269 } else {
5270 // return user + sys since the cost is the same
5271 return slow_thread_cpu_time(Thread::current(), true /* user + sys */);
5272 }
5273 }
5274
5275 jlong os::thread_cpu_time(Thread* thread) {
5276 // consistent with what current_thread_cpu_time() returns
5277 if (os::Linux::supports_fast_thread_cpu_time()) {
5278 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread));
5279 } else {
5280 return slow_thread_cpu_time(thread, true /* user + sys */);
5281 }
5282 }
5283
5284 jlong os::current_thread_cpu_time(bool user_sys_cpu_time) {
5285 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
5286 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
5287 } else {
5288 return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time);
5289 }
5290 }
5291
5292 jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
5293 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
5294 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread));
5295 } else {
5296 return slow_thread_cpu_time(thread, user_sys_cpu_time);
5297 }
5298 }
5299
5300 // -1 on error.
5301 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
5302 pid_t tid = thread->osthread()->thread_id();
5303 char *s;
5304 char stat[2048];
5305 int statlen;
5306 char proc_name[64];
5307 int count;
5308 long sys_time, user_time;
5309 char cdummy;
5310 int idummy;
5311 long ldummy;
5312 FILE *fp;
5313
5314 snprintf(proc_name, 64, "/proc/self/task/%d/stat", tid);
5315 fp = fopen(proc_name, "r");
5316 if (fp == NULL) return -1;
5317 statlen = fread(stat, 1, 2047, fp);
5318 stat[statlen] = '\0';
5319 fclose(fp);
5320
5321 // Skip pid and the command string. Note that we could be dealing with
5322 // weird command names, e.g. user could decide to rename java launcher
5323 // to "java 1.4.2 :)", then the stat file would look like
5324 // 1234 (java 1.4.2 :)) R ... ...
5325 // We don't really need to know the command string, just find the last
5326 // occurrence of ")" and then start parsing from there. See bug 4726580.
5327 s = strrchr(stat, ')');
5328 if (s == NULL) return -1;
5329
5330 // Skip blank chars
5331 do { s++; } while (s && isspace(*s));
5332
5333 count = sscanf(s,"%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu",
5334 &cdummy, &idummy, &idummy, &idummy, &idummy, &idummy,
5335 &ldummy, &ldummy, &ldummy, &ldummy, &ldummy,
5336 &user_time, &sys_time);
5337 if (count != 13) return -1;
5338 if (user_sys_cpu_time) {
5339 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec);
5340 } else {
5341 return (jlong)user_time * (1000000000 / clock_tics_per_sec);
5342 }
5343 }
5344
5345 void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
5346 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits
5347 info_ptr->may_skip_backward = false; // elapsed time not wall time
5348 info_ptr->may_skip_forward = false; // elapsed time not wall time
5349 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned
5350 }
5351
5352 void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
5353 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits
5354 info_ptr->may_skip_backward = false; // elapsed time not wall time
5355 info_ptr->may_skip_forward = false; // elapsed time not wall time
5356 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned
5357 }
5358
5359 bool os::is_thread_cpu_time_supported() {
5360 return true;
5361 }
5362
5363 // System loadavg support. Returns -1 if load average cannot be obtained.
5364 // Linux doesn't yet have a (official) notion of processor sets,
5365 // so just return the system wide load average.
5366 int os::loadavg(double loadavg[], int nelem) {
5367 return ::getloadavg(loadavg, nelem);
5368 }
5369
5370 void os::pause() {
5371 char filename[MAX_PATH];
5372 if (PauseAtStartupFile && PauseAtStartupFile[0]) {
5373 jio_snprintf(filename, MAX_PATH, PauseAtStartupFile);
5374 } else {
5375 jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id());
5376 }
5377
5378 int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
5379 if (fd != -1) {
5380 struct stat buf;
5381 ::close(fd);
5382 while (::stat(filename, &buf) == 0) {
5383 (void)::poll(NULL, 0, 100);
5384 }
5385 } else {
5386 jio_fprintf(stderr,
5387 "Could not open pause file '%s', continuing immediately.\n", filename);
5388 }
5389 }
5390
5391
5392 // Refer to the comments in os_solaris.cpp park-unpark. The next two
5393 // comment paragraphs are worth repeating here:
5394 //
5395 // Assumption:
5396 // Only one parker can exist on an event, which is why we allocate
5397 // them per-thread. Multiple unparkers can coexist.
5398 //
5399 // _Event serves as a restricted-range semaphore.
5400 // -1 : thread is blocked, i.e. there is a waiter
5401 // 0 : neutral: thread is running or ready,
5402 // could have been signaled after a wait started
5403 // 1 : signaled - thread is running or ready
5404 //
5405 // Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can
5406 // hang indefinitely. For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable.
5407 // For specifics regarding the bug see GLIBC BUGID 261237 :
5408 // http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html.
5409 // Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future
5410 // will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar
5411 // is used. (The simple C test-case provided in the GLIBC bug report manifests the
5412 // hang). The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos()
5413 // and monitorenter when we're using 1-0 locking. All those operations may result in
5414 // calls to pthread_cond_timedwait(). Using LD_ASSUME_KERNEL to use an older version
5415 // of libpthread avoids the problem, but isn't practical.
5416 //
5417 // Possible remedies:
5418 //
5419 // 1. Establish a minimum relative wait time. 50 to 100 msecs seems to work.
5420 // This is palliative and probabilistic, however. If the thread is preempted
5421 // between the call to compute_abstime() and pthread_cond_timedwait(), more
5422 // than the minimum period may have passed, and the abstime may be stale (in the
5423 // past) resultin in a hang. Using this technique reduces the odds of a hang
5424 // but the JVM is still vulnerable, particularly on heavily loaded systems.
5425 //
5426 // 2. Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead
5427 // of the usual flag-condvar-mutex idiom. The write side of the pipe is set
5428 // NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo)
5429 // reduces to poll()+read(). This works well, but consumes 2 FDs per extant
5430 // thread.
5431 //
5432 // 3. Embargo pthread_cond_timedwait() and implement a native "chron" thread
5433 // that manages timeouts. We'd emulate pthread_cond_timedwait() by enqueuing
5434 // a timeout request to the chron thread and then blocking via pthread_cond_wait().
5435 // This also works well. In fact it avoids kernel-level scalability impediments
5436 // on certain platforms that don't handle lots of active pthread_cond_timedwait()
5437 // timers in a graceful fashion.
5438 //
5439 // 4. When the abstime value is in the past it appears that control returns
5440 // correctly from pthread_cond_timedwait(), but the condvar is left corrupt.
5441 // Subsequent timedwait/wait calls may hang indefinitely. Given that, we
5442 // can avoid the problem by reinitializing the condvar -- by cond_destroy()
5443 // followed by cond_init() -- after all calls to pthread_cond_timedwait().
5444 // It may be possible to avoid reinitialization by checking the return
5445 // value from pthread_cond_timedwait(). In addition to reinitializing the
5446 // condvar we must establish the invariant that cond_signal() is only called
5447 // within critical sections protected by the adjunct mutex. This prevents
5448 // cond_signal() from "seeing" a condvar that's in the midst of being
5449 // reinitialized or that is corrupt. Sadly, this invariant obviates the
5450 // desirable signal-after-unlock optimization that avoids futile context switching.
5451 //
5452 // I'm also concerned that some versions of NTPL might allocate an auxilliary
5453 // structure when a condvar is used or initialized. cond_destroy() would
5454 // release the helper structure. Our reinitialize-after-timedwait fix
5455 // put excessive stress on malloc/free and locks protecting the c-heap.
5456 //
5457 // We currently use (4). See the WorkAroundNTPLTimedWaitHang flag.
5458 // It may be possible to refine (4) by checking the kernel and NTPL verisons
5459 // and only enabling the work-around for vulnerable environments.
5460
5461 // utility to compute the abstime argument to timedwait:
5462 // millis is the relative timeout time
5463 // abstime will be the absolute timeout time
5464 // TODO: replace compute_abstime() with unpackTime()
5465
5466 static struct timespec* compute_abstime(timespec* abstime, jlong millis) {
5467 if (millis < 0) millis = 0;
5468
5469 jlong seconds = millis / 1000;
5470 millis %= 1000;
5471 if (seconds > 50000000) { // see man cond_timedwait(3T)
5472 seconds = 50000000;
5473 }
5474
5475 if (os::supports_monotonic_clock()) {
5476 struct timespec now;
5477 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now);
5478 assert_status(status == 0, status, "clock_gettime");
5479 abstime->tv_sec = now.tv_sec + seconds;
5480 long nanos = now.tv_nsec + millis * NANOSECS_PER_MILLISEC;
5481 if (nanos >= NANOSECS_PER_SEC) {
5482 abstime->tv_sec += 1;
5483 nanos -= NANOSECS_PER_SEC;
5484 }
5485 abstime->tv_nsec = nanos;
5486 } else {
5487 struct timeval now;
5488 int status = gettimeofday(&now, NULL);
5489 assert(status == 0, "gettimeofday");
5490 abstime->tv_sec = now.tv_sec + seconds;
5491 long usec = now.tv_usec + millis * 1000;
5492 if (usec >= 1000000) {
5493 abstime->tv_sec += 1;
5494 usec -= 1000000;
5495 }
5496 abstime->tv_nsec = usec * 1000;
5497 }
5498 return abstime;
5499 }
5500
5501 void os::PlatformEvent::park() { // AKA "down()"
5502 // Transitions for _Event:
5503 // -1 => -1 : illegal
5504 // 1 => 0 : pass - return immediately
5505 // 0 => -1 : block; then set _Event to 0 before returning
5506
5507 // Invariant: Only the thread associated with the Event/PlatformEvent
5508 // may call park().
5509 // TODO: assert that _Assoc != NULL or _Assoc == Self
5510 assert(_nParked == 0, "invariant");
5511
5512 int v;
5513 for (;;) {
5514 v = _Event;
5515 if (Atomic::cmpxchg(v-1, &_Event, v) == v) break;
5516 }
5517 guarantee(v >= 0, "invariant");
5518 if (v == 0) {
5519 // Do this the hard way by blocking ...
5520 int status = pthread_mutex_lock(_mutex);
5521 assert_status(status == 0, status, "mutex_lock");
5522 guarantee(_nParked == 0, "invariant");
5523 ++_nParked;
5524 while (_Event < 0) {
5525 status = pthread_cond_wait(_cond, _mutex);
5526 // for some reason, under 2.7 lwp_cond_wait() may return ETIME ...
5527 // Treat this the same as if the wait was interrupted
5528 if (status == ETIME) { status = EINTR; }
5529 assert_status(status == 0 || status == EINTR, status, "cond_wait");
5530 }
5531 --_nParked;
5532
5533 _Event = 0;
5534 status = pthread_mutex_unlock(_mutex);
5535 assert_status(status == 0, status, "mutex_unlock");
5536 // Paranoia to ensure our locked and lock-free paths interact
5537 // correctly with each other.
5538 OrderAccess::fence();
5539 }
5540 guarantee(_Event >= 0, "invariant");
5541 }
5542
5543 int os::PlatformEvent::park(jlong millis) {
5544 // Transitions for _Event:
5545 // -1 => -1 : illegal
5546 // 1 => 0 : pass - return immediately
5547 // 0 => -1 : block; then set _Event to 0 before returning
5548
5549 guarantee(_nParked == 0, "invariant");
5550
5551 int v;
5552 for (;;) {
5553 v = _Event;
5554 if (Atomic::cmpxchg(v-1, &_Event, v) == v) break;
5555 }
5556 guarantee(v >= 0, "invariant");
5557 if (v != 0) return OS_OK;
5558
5559 // We do this the hard way, by blocking the thread.
5560 // Consider enforcing a minimum timeout value.
5561 struct timespec abst;
5562 compute_abstime(&abst, millis);
5563
5564 int ret = OS_TIMEOUT;
5565 int status = pthread_mutex_lock(_mutex);
5566 assert_status(status == 0, status, "mutex_lock");
5567 guarantee(_nParked == 0, "invariant");
5568 ++_nParked;
5569
5570 // Object.wait(timo) will return because of
5571 // (a) notification
5572 // (b) timeout
5573 // (c) thread.interrupt
5574 //
5575 // Thread.interrupt and object.notify{All} both call Event::set.
5576 // That is, we treat thread.interrupt as a special case of notification.
5577 // We ignore spurious OS wakeups unless FilterSpuriousWakeups is false.
5578 // We assume all ETIME returns are valid.
5579 //
5580 // TODO: properly differentiate simultaneous notify+interrupt.
5581 // In that case, we should propagate the notify to another waiter.
5582
5583 while (_Event < 0) {
5584 status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst);
5585 if (status != 0 && WorkAroundNPTLTimedWaitHang) {
5586 pthread_cond_destroy(_cond);
5587 pthread_cond_init(_cond, os::Linux::condAttr());
5588 }
5589 assert_status(status == 0 || status == EINTR ||
5590 status == ETIME || status == ETIMEDOUT,
5591 status, "cond_timedwait");
5592 if (!FilterSpuriousWakeups) break; // previous semantics
5593 if (status == ETIME || status == ETIMEDOUT) break;
5594 // We consume and ignore EINTR and spurious wakeups.
5595 }
5596 --_nParked;
5597 if (_Event >= 0) {
5598 ret = OS_OK;
5599 }
5600 _Event = 0;
5601 status = pthread_mutex_unlock(_mutex);
5602 assert_status(status == 0, status, "mutex_unlock");
5603 assert(_nParked == 0, "invariant");
5604 // Paranoia to ensure our locked and lock-free paths interact
5605 // correctly with each other.
5606 OrderAccess::fence();
5607 return ret;
5608 }
5609
5610 void os::PlatformEvent::unpark() {
5611 // Transitions for _Event:
5612 // 0 => 1 : just return
5613 // 1 => 1 : just return
5614 // -1 => either 0 or 1; must signal target thread
5615 // That is, we can safely transition _Event from -1 to either
5616 // 0 or 1.
5617 // See also: "Semaphores in Plan 9" by Mullender & Cox
5618 //
5619 // Note: Forcing a transition from "-1" to "1" on an unpark() means
5620 // that it will take two back-to-back park() calls for the owning
5621 // thread to block. This has the benefit of forcing a spurious return
5622 // from the first park() call after an unpark() call which will help
5623 // shake out uses of park() and unpark() without condition variables.
5624
5625 if (Atomic::xchg(1, &_Event) >= 0) return;
5626
5627 // Wait for the thread associated with the event to vacate
5628 int status = pthread_mutex_lock(_mutex);
5629 assert_status(status == 0, status, "mutex_lock");
5630 int AnyWaiters = _nParked;
5631 assert(AnyWaiters == 0 || AnyWaiters == 1, "invariant");
5632 if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) {
5633 AnyWaiters = 0;
5634 pthread_cond_signal(_cond);
5635 }
5636 status = pthread_mutex_unlock(_mutex);
5637 assert_status(status == 0, status, "mutex_unlock");
5638 if (AnyWaiters != 0) {
5639 // Note that we signal() *after* dropping the lock for "immortal" Events.
5640 // This is safe and avoids a common class of futile wakeups. In rare
5641 // circumstances this can cause a thread to return prematurely from
5642 // cond_{timed}wait() but the spurious wakeup is benign and the victim
5643 // will simply re-test the condition and re-park itself.
5644 // This provides particular benefit if the underlying platform does not
5645 // provide wait morphing.
5646 status = pthread_cond_signal(_cond);
5647 assert_status(status == 0, status, "cond_signal");
5648 }
5649 }
5650
5651
5652 // JSR166
5653 // -------------------------------------------------------
5654
5655 // The solaris and linux implementations of park/unpark are fairly
5656 // conservative for now, but can be improved. They currently use a
5657 // mutex/condvar pair, plus a a count.
5658 // Park decrements count if > 0, else does a condvar wait. Unpark
5659 // sets count to 1 and signals condvar. Only one thread ever waits
5660 // on the condvar. Contention seen when trying to park implies that someone
5661 // is unparking you, so don't wait. And spurious returns are fine, so there
5662 // is no need to track notifications.
5663
5664 // This code is common to linux and solaris and will be moved to a
5665 // common place in dolphin.
5666 //
5667 // The passed in time value is either a relative time in nanoseconds
5668 // or an absolute time in milliseconds. Either way it has to be unpacked
5669 // into suitable seconds and nanoseconds components and stored in the
5670 // given timespec structure.
5671 // Given time is a 64-bit value and the time_t used in the timespec is only
5672 // a signed-32-bit value (except on 64-bit Linux) we have to watch for
5673 // overflow if times way in the future are given. Further on Solaris versions
5674 // prior to 10 there is a restriction (see cond_timedwait) that the specified
5675 // number of seconds, in abstime, is less than current_time + 100,000,000.
5676 // As it will be 28 years before "now + 100000000" will overflow we can
5677 // ignore overflow and just impose a hard-limit on seconds using the value
5678 // of "now + 100,000,000". This places a limit on the timeout of about 3.17
5679 // years from "now".
5680
5681 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) {
5682 assert(time > 0, "convertTime");
5683 time_t max_secs = 0;
5684
5685 if (!os::supports_monotonic_clock() || isAbsolute) {
5686 struct timeval now;
5687 int status = gettimeofday(&now, NULL);
5688 assert(status == 0, "gettimeofday");
5689
5690 max_secs = now.tv_sec + MAX_SECS;
5691
5692 if (isAbsolute) {
5693 jlong secs = time / 1000;
5694 if (secs > max_secs) {
5695 absTime->tv_sec = max_secs;
5696 } else {
5697 absTime->tv_sec = secs;
5698 }
5699 absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC;
5700 } else {
5701 jlong secs = time / NANOSECS_PER_SEC;
5702 if (secs >= MAX_SECS) {
5703 absTime->tv_sec = max_secs;
5704 absTime->tv_nsec = 0;
5705 } else {
5706 absTime->tv_sec = now.tv_sec + secs;
5707 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000;
5708 if (absTime->tv_nsec >= NANOSECS_PER_SEC) {
5709 absTime->tv_nsec -= NANOSECS_PER_SEC;
5710 ++absTime->tv_sec; // note: this must be <= max_secs
5711 }
5712 }
5713 }
5714 } else {
5715 // must be relative using monotonic clock
5716 struct timespec now;
5717 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now);
5718 assert_status(status == 0, status, "clock_gettime");
5719 max_secs = now.tv_sec + MAX_SECS;
5720 jlong secs = time / NANOSECS_PER_SEC;
5721 if (secs >= MAX_SECS) {
5722 absTime->tv_sec = max_secs;
5723 absTime->tv_nsec = 0;
5724 } else {
5725 absTime->tv_sec = now.tv_sec + secs;
5726 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_nsec;
5727 if (absTime->tv_nsec >= NANOSECS_PER_SEC) {
5728 absTime->tv_nsec -= NANOSECS_PER_SEC;
5729 ++absTime->tv_sec; // note: this must be <= max_secs
5730 }
5731 }
5732 }
5733 assert(absTime->tv_sec >= 0, "tv_sec < 0");
5734 assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs");
5735 assert(absTime->tv_nsec >= 0, "tv_nsec < 0");
5736 assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec");
5737 }
5738
5739 void Parker::park(bool isAbsolute, jlong time) {
5740 // Ideally we'd do something useful while spinning, such
5741 // as calling unpackTime().
5742
5743 // Optional fast-path check:
5744 // Return immediately if a permit is available.
5745 // We depend on Atomic::xchg() having full barrier semantics
5746 // since we are doing a lock-free update to _counter.
5747 if (Atomic::xchg(0, &_counter) > 0) return;
5748
5749 Thread* thread = Thread::current();
5750 assert(thread->is_Java_thread(), "Must be JavaThread");
5751 JavaThread *jt = (JavaThread *)thread;
5752
5753 // Optional optimization -- avoid state transitions if there's an interrupt pending.
5754 // Check interrupt before trying to wait
5755 if (Thread::is_interrupted(thread, false)) {
5756 return;
5757 }
5758
5759 // Next, demultiplex/decode time arguments
5760 timespec absTime;
5761 if (time < 0 || (isAbsolute && time == 0)) { // don't wait at all
5762 return;
5763 }
5764 if (time > 0) {
5765 unpackTime(&absTime, isAbsolute, time);
5766 }
5767
5768
5769 // Enter safepoint region
5770 // Beware of deadlocks such as 6317397.
5771 // The per-thread Parker:: mutex is a classic leaf-lock.
5772 // In particular a thread must never block on the Threads_lock while
5773 // holding the Parker:: mutex. If safepoints are pending both the
5774 // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock.
5775 ThreadBlockInVM tbivm(jt);
5776
5777 // Don't wait if cannot get lock since interference arises from
5778 // unblocking. Also. check interrupt before trying wait
5779 if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) {
5780 return;
5781 }
5782
5783 int status;
5784 if (_counter > 0) { // no wait needed
5785 _counter = 0;
5786 status = pthread_mutex_unlock(_mutex);
5787 assert(status == 0, "invariant");
5788 // Paranoia to ensure our locked and lock-free paths interact
5789 // correctly with each other and Java-level accesses.
5790 OrderAccess::fence();
5791 return;
5792 }
5793
5794 #ifdef ASSERT
5795 // Don't catch signals while blocked; let the running threads have the signals.
5796 // (This allows a debugger to break into the running thread.)
5797 sigset_t oldsigs;
5798 sigset_t* allowdebug_blocked = os::Linux::allowdebug_blocked_signals();
5799 pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs);
5800 #endif
5801
5802 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */);
5803 jt->set_suspend_equivalent();
5804 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
5805
5806 assert(_cur_index == -1, "invariant");
5807 if (time == 0) {
5808 _cur_index = REL_INDEX; // arbitrary choice when not timed
5809 status = pthread_cond_wait(&_cond[_cur_index], _mutex);
5810 } else {
5811 _cur_index = isAbsolute ? ABS_INDEX : REL_INDEX;
5812 status = os::Linux::safe_cond_timedwait(&_cond[_cur_index], _mutex, &absTime);
5813 if (status != 0 && WorkAroundNPTLTimedWaitHang) {
5814 pthread_cond_destroy(&_cond[_cur_index]);
5815 pthread_cond_init(&_cond[_cur_index], isAbsolute ? NULL : os::Linux::condAttr());
5816 }
5817 }
5818 _cur_index = -1;
5819 assert_status(status == 0 || status == EINTR ||
5820 status == ETIME || status == ETIMEDOUT,
5821 status, "cond_timedwait");
5822
5823 #ifdef ASSERT
5824 pthread_sigmask(SIG_SETMASK, &oldsigs, NULL);
5825 #endif
5826
5827 _counter = 0;
5828 status = pthread_mutex_unlock(_mutex);
5829 assert_status(status == 0, status, "invariant");
5830 // Paranoia to ensure our locked and lock-free paths interact
5831 // correctly with each other and Java-level accesses.
5832 OrderAccess::fence();
5833
5834 // If externally suspended while waiting, re-suspend
5835 if (jt->handle_special_suspend_equivalent_condition()) {
5836 jt->java_suspend_self();
5837 }
5838 }
5839
5840 void Parker::unpark() {
5841 int status = pthread_mutex_lock(_mutex);
5842 assert(status == 0, "invariant");
5843 const int s = _counter;
5844 _counter = 1;
5845 if (s < 1) {
5846 // thread might be parked
5847 if (_cur_index != -1) {
5848 // thread is definitely parked
5849 if (WorkAroundNPTLTimedWaitHang) {
5850 status = pthread_cond_signal(&_cond[_cur_index]);
5851 assert(status == 0, "invariant");
5852 status = pthread_mutex_unlock(_mutex);
5853 assert(status == 0, "invariant");
5854 } else {
5855 status = pthread_mutex_unlock(_mutex);
5856 assert(status == 0, "invariant");
5857 status = pthread_cond_signal(&_cond[_cur_index]);
5858 assert(status == 0, "invariant");
5859 }
5860 } else {
5861 pthread_mutex_unlock(_mutex);
5862 assert(status == 0, "invariant");
5863 }
5864 } else {
5865 pthread_mutex_unlock(_mutex);
5866 assert(status == 0, "invariant");
5867 }
5868 }
5869
5870
5871 extern char** environ;
5872
5873 #ifndef __NR_fork
5874 #define __NR_fork IA32_ONLY(2) IA64_ONLY(not defined) AMD64_ONLY(57)
5875 #endif
5876
5877 #ifndef __NR_execve
5878 #define __NR_execve IA32_ONLY(11) IA64_ONLY(1033) AMD64_ONLY(59)
5879 #endif
5880
5881 // Run the specified command in a separate process. Return its exit value,
5882 // or -1 on failure (e.g. can't fork a new process).
5883 // Unlike system(), this function can be called from signal handler. It
5884 // doesn't block SIGINT et al.
5885 int os::fork_and_exec(char* cmd) {
5886 const char * argv[4] = {"sh", "-c", cmd, NULL};
5887
5888 // fork() in LinuxThreads/NPTL is not async-safe. It needs to run
5889 // pthread_atfork handlers and reset pthread library. All we need is a
5890 // separate process to execve. Make a direct syscall to fork process.
5891 // On IA64 there's no fork syscall, we have to use fork() and hope for
5892 // the best...
5893 pid_t pid = NOT_IA64(syscall(__NR_fork);)
5894 IA64_ONLY(fork();)
5895
5896 if (pid < 0) {
5897 // fork failed
5898 return -1;
5899
5900 } else if (pid == 0) {
5901 // child process
5902
5903 // execve() in LinuxThreads will call pthread_kill_other_threads_np()
5904 // first to kill every thread on the thread list. Because this list is
5905 // not reset by fork() (see notes above), execve() will instead kill
5906 // every thread in the parent process. We know this is the only thread
5907 // in the new process, so make a system call directly.
5908 // IA64 should use normal execve() from glibc to match the glibc fork()
5909 // above.
5910 NOT_IA64(syscall(__NR_execve, "/bin/sh", argv, environ);)
5911 IA64_ONLY(execve("/bin/sh", (char* const*)argv, environ);)
5912
5913 // execve failed
5914 _exit(-1);
5915
5916 } else {
5917 // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't
5918 // care about the actual exit code, for now.
5919
5920 int status;
5921
5922 // Wait for the child process to exit. This returns immediately if
5923 // the child has already exited. */
5924 while (waitpid(pid, &status, 0) < 0) {
5925 switch (errno) {
5926 case ECHILD: return 0;
5927 case EINTR: break;
5928 default: return -1;
5929 }
5930 }
5931
5932 if (WIFEXITED(status)) {
5933 // The child exited normally; get its exit code.
5934 return WEXITSTATUS(status);
5935 } else if (WIFSIGNALED(status)) {
5936 // The child exited because of a signal
5937 // The best value to return is 0x80 + signal number,
5938 // because that is what all Unix shells do, and because
5939 // it allows callers to distinguish between process exit and
5940 // process death by signal.
5941 return 0x80 + WTERMSIG(status);
5942 } else {
5943 // Unknown exit code; pass it through
5944 return status;
5945 }
5946 }
5947 }
5948
5949 // is_headless_jre()
5950 //
5951 // Test for the existence of xawt/libmawt.so or libawt_xawt.so
5952 // in order to report if we are running in a headless jre
5953 //
5954 // Since JDK8 xawt/libmawt.so was moved into the same directory
5955 // as libawt.so, and renamed libawt_xawt.so
5956 //
5957 bool os::is_headless_jre() {
5958 struct stat statbuf;
5959 char buf[MAXPATHLEN];
5960 char libmawtpath[MAXPATHLEN];
5961 const char *xawtstr = "/xawt/libmawt.so";
5962 const char *new_xawtstr = "/libawt_xawt.so";
5963 char *p;
5964
5965 // Get path to libjvm.so
5966 os::jvm_path(buf, sizeof(buf));
5967
5968 // Get rid of libjvm.so
5969 p = strrchr(buf, '/');
5970 if (p == NULL) {
5971 return false;
5972 } else {
5973 *p = '\0';
5974 }
5975
5976 // Get rid of client or server
5977 p = strrchr(buf, '/');
5978 if (p == NULL) {
5979 return false;
5980 } else {
5981 *p = '\0';
5982 }
5983
5984 // check xawt/libmawt.so
5985 strcpy(libmawtpath, buf);
5986 strcat(libmawtpath, xawtstr);
5987 if (::stat(libmawtpath, &statbuf) == 0) return false;
5988
5989 // check libawt_xawt.so
5990 strcpy(libmawtpath, buf);
5991 strcat(libmawtpath, new_xawtstr);
5992 if (::stat(libmawtpath, &statbuf) == 0) return false;
5993
5994 return true;
5995 }
5996
5997 // Get the default path to the core file
5998 // Returns the length of the string
5999 int os::get_core_path(char* buffer, size_t bufferSize) {
6000 /*
6001 * Max length of /proc/sys/kernel/core_pattern is 128 characters.
6002 * See https://www.kernel.org/doc/Documentation/sysctl/kernel.txt
6003 */
6004 const int core_pattern_len = 129;
6005 char core_pattern[core_pattern_len] = {0};
6006
6007 int core_pattern_file = ::open("/proc/sys/kernel/core_pattern", O_RDONLY);
6008 if (core_pattern_file != -1) {
6009 ssize_t ret = ::read(core_pattern_file, core_pattern, core_pattern_len);
6010 ::close(core_pattern_file);
6011
6012 if (ret > 0) {
6013 char *last_char = core_pattern + strlen(core_pattern) - 1;
6014
6015 if (*last_char == '\n') {
6016 *last_char = '\0';
6017 }
6018 }
6019 }
6020
6021 if (strlen(core_pattern) == 0) {
6022 return 0;
6023 }
6024
6025 char *pid_pos = strstr(core_pattern, "%p");
6026 size_t written;
6027
6028 if (core_pattern[0] == '/') {
6029 written = jio_snprintf(buffer, bufferSize, core_pattern);
6030 } else {
6031 char cwd[PATH_MAX];
6032
6033 const char* p = get_current_directory(cwd, PATH_MAX);
6034 if (p == NULL) {
6035 assert(p != NULL, "failed to get current directory");
6036 return 0;
6037 }
6038
6039 if (core_pattern[0] == '|') {
6040 written = jio_snprintf(buffer, bufferSize,
6041 "\"%s\" (or dumping to %s/core.%d)",
6042 &core_pattern[1], p, current_process_id());
6043 } else {
6044 written = jio_snprintf(buffer, bufferSize, "%s/%s", p, core_pattern);
6045 }
6046 }
6047
6048 if ((written >= 0) && (written < bufferSize)
6049 && (pid_pos == NULL) && (core_pattern[0] != '|')) {
6050 int core_uses_pid_file = ::open("/proc/sys/kernel/core_uses_pid", O_RDONLY);
6051
6052 if (core_uses_pid_file != -1) {
6053 char core_uses_pid = 0;
6054 ssize_t ret = ::read(core_uses_pid_file, &core_uses_pid, 1);
6055 ::close(core_uses_pid_file);
6056
6057 if (core_uses_pid == '1'){
6058 jio_snprintf(buffer + written, bufferSize - written,
6059 ".%d", current_process_id());
6060 }
6061 }
6062 }
6063
6064 return strlen(buffer);
6065 }
6066
6067 /////////////// Unit tests ///////////////
6068
6069 #ifndef PRODUCT
6070
6071 #define test_log(...) \
6072 do { \
6073 if (VerboseInternalVMTests) { \
6074 tty->print_cr(__VA_ARGS__); \
6075 tty->flush(); \
6076 } \
6077 } while (false)
6078
6079 class TestReserveMemorySpecial : AllStatic {
6080 public:
6081 static void small_page_write(void* addr, size_t size) {
6082 size_t page_size = os::vm_page_size();
6083
6084 char* end = (char*)addr + size;
6085 for (char* p = (char*)addr; p < end; p += page_size) {
6086 *p = 1;
6087 }
6088 }
6089
6090 static void test_reserve_memory_special_huge_tlbfs_only(size_t size) {
6091 if (!UseHugeTLBFS) {
6092 return;
6093 }
6094
6095 test_log("test_reserve_memory_special_huge_tlbfs_only(" SIZE_FORMAT ")", size);
6096
6097 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_only(size, NULL, false);
6098
6099 if (addr != NULL) {
6100 small_page_write(addr, size);
6101
6102 os::Linux::release_memory_special_huge_tlbfs(addr, size);
6103 }
6104 }
6105
6106 static void test_reserve_memory_special_huge_tlbfs_only() {
6107 if (!UseHugeTLBFS) {
6108 return;
6109 }
6110
6111 size_t lp = os::large_page_size();
6112
6113 for (size_t size = lp; size <= lp * 10; size += lp) {
6114 test_reserve_memory_special_huge_tlbfs_only(size);
6115 }
6116 }
6117
6118 static void test_reserve_memory_special_huge_tlbfs_mixed(size_t size, size_t alignment) {
6119 if (!UseHugeTLBFS) {
6120 return;
6121 }
6122
6123 test_log("test_reserve_memory_special_huge_tlbfs_mixed(" SIZE_FORMAT ", " SIZE_FORMAT ")",
6124 size, alignment);
6125
6126 assert(size >= os::large_page_size(), "Incorrect input to test");
6127
6128 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, NULL, false);
6129
6130 if (addr != NULL) {
6131 small_page_write(addr, size);
6132
6133 os::Linux::release_memory_special_huge_tlbfs(addr, size);
6134 }
6135 }
6136
6137 static void test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(size_t size) {
6138 size_t lp = os::large_page_size();
6139 size_t ag = os::vm_allocation_granularity();
6140
6141 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) {
6142 test_reserve_memory_special_huge_tlbfs_mixed(size, alignment);
6143 }
6144 }
6145
6146 static void test_reserve_memory_special_huge_tlbfs_mixed() {
6147 size_t lp = os::large_page_size();
6148 size_t ag = os::vm_allocation_granularity();
6149
6150 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp);
6151 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + ag);
6152 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + lp / 2);
6153 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2);
6154 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 + ag);
6155 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 - ag);
6156 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 + lp / 2);
6157 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10);
6158 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10 + lp / 2);
6159 }
6160
6161 static void test_reserve_memory_special_huge_tlbfs() {
6162 if (!UseHugeTLBFS) {
6163 return;
6164 }
6165
6166 test_reserve_memory_special_huge_tlbfs_only();
6167 test_reserve_memory_special_huge_tlbfs_mixed();
6168 }
6169
6170 static void test_reserve_memory_special_shm(size_t size, size_t alignment) {
6171 if (!UseSHM) {
6172 return;
6173 }
6174
6175 test_log("test_reserve_memory_special_shm(" SIZE_FORMAT ", " SIZE_FORMAT ")", size, alignment);
6176
6177 char* addr = os::Linux::reserve_memory_special_shm(size, alignment, NULL, false);
6178
6179 if (addr != NULL) {
6180 assert(is_ptr_aligned(addr, alignment), "Check");
6181 assert(is_ptr_aligned(addr, os::large_page_size()), "Check");
6182
6183 small_page_write(addr, size);
6184
6185 os::Linux::release_memory_special_shm(addr, size);
6186 }
6187 }
6188
6189 static void test_reserve_memory_special_shm() {
6190 size_t lp = os::large_page_size();
6191 size_t ag = os::vm_allocation_granularity();
6192
6193 for (size_t size = ag; size < lp * 3; size += ag) {
6194 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) {
6195 test_reserve_memory_special_shm(size, alignment);
6196 }
6197 }
6198 }
6199
6200 static void test() {
6201 test_reserve_memory_special_huge_tlbfs();
6202 test_reserve_memory_special_shm();
6203 }
6204 };
6205
6206 void TestReserveMemorySpecial_test() {
6207 TestReserveMemorySpecial::test();
6208 }
6209
6210 #endif