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 // Declarations
162 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time);
163
164 // utility functions
165
166 static int SR_initialize();
167
168 julong os::available_memory() {
169 return Linux::available_memory();
170 }
171
172 julong os::Linux::available_memory() {
173 // values in struct sysinfo are "unsigned long"
174 struct sysinfo si;
175 sysinfo(&si);
176
177 return (julong)si.freeram * si.mem_unit;
178 }
179
180 julong os::physical_memory() {
181 return Linux::physical_memory();
182 }
183
184 // Return true if user is running as root.
185
186 bool os::have_special_privileges() {
187 static bool init = false;
188 static bool privileges = false;
189 if (!init) {
190 privileges = (getuid() != geteuid()) || (getgid() != getegid());
191 init = true;
192 }
193 return privileges;
194 }
195
196
197 #ifndef SYS_gettid
198 // i386: 224, ia64: 1105, amd64: 186, sparc 143
199 #ifdef __ia64__
200 #define SYS_gettid 1105
201 #else
202 #ifdef __i386__
203 #define SYS_gettid 224
204 #else
205 #ifdef __amd64__
206 #define SYS_gettid 186
207 #else
208 #ifdef __sparc__
209 #define SYS_gettid 143
210 #else
211 #error define gettid for the arch
212 #endif
213 #endif
214 #endif
215 #endif
216 #endif
217
218 // Cpu architecture string
219 static char cpu_arch[] = HOTSPOT_LIB_ARCH;
220
221
222 // pid_t gettid()
223 //
224 // Returns the kernel thread id of the currently running thread. Kernel
225 // thread id is used to access /proc.
226 //
227 // (Note that getpid() on LinuxThreads returns kernel thread id too; but
228 // on NPTL, it returns the same pid for all threads, as required by POSIX.)
229 //
230 pid_t os::Linux::gettid() {
231 int rslt = syscall(SYS_gettid);
232 if (rslt == -1) {
233 // old kernel, no NPTL support
234 return getpid();
235 } else {
236 return (pid_t)rslt;
237 }
238 }
239
240 // Most versions of linux have a bug where the number of processors are
241 // determined by looking at the /proc file system. In a chroot environment,
242 // the system call returns 1. This causes the VM to act as if it is
243 // a single processor and elide locking (see is_MP() call).
244 static bool unsafe_chroot_detected = false;
245 static const char *unstable_chroot_error = "/proc file system not found.\n"
246 "Java may be unstable running multithreaded in a chroot "
247 "environment on Linux when /proc filesystem is not mounted.";
248
249 void os::Linux::initialize_system_info() {
250 set_processor_count(sysconf(_SC_NPROCESSORS_CONF));
251 if (processor_count() == 1) {
252 pid_t pid = os::Linux::gettid();
253 char fname[32];
254 jio_snprintf(fname, sizeof(fname), "/proc/%d", pid);
255 FILE *fp = fopen(fname, "r");
256 if (fp == NULL) {
257 unsafe_chroot_detected = true;
258 } else {
259 fclose(fp);
260 }
261 }
262 _physical_memory = (julong)sysconf(_SC_PHYS_PAGES) * (julong)sysconf(_SC_PAGESIZE);
263 assert(processor_count() > 0, "linux error");
264 }
265
266 void os::init_system_properties_values() {
267 // The next steps are taken in the product version:
268 //
269 // Obtain the JAVA_HOME value from the location of libjvm.so.
270 // This library should be located at:
271 // <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm.so.
272 //
273 // If "/jre/lib/" appears at the right place in the path, then we
274 // assume libjvm.so is installed in a JDK and we use this path.
275 //
276 // Otherwise exit with message: "Could not create the Java virtual machine."
277 //
278 // The following extra steps are taken in the debugging version:
279 //
280 // If "/jre/lib/" does NOT appear at the right place in the path
281 // instead of exit check for $JAVA_HOME environment variable.
282 //
283 // If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>,
284 // then we append a fake suffix "hotspot/libjvm.so" to this path so
285 // it looks like libjvm.so is installed there
286 // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm.so.
287 //
288 // Otherwise exit.
289 //
290 // Important note: if the location of libjvm.so changes this
291 // code needs to be changed accordingly.
292
293 // See ld(1):
294 // The linker uses the following search paths to locate required
295 // shared libraries:
296 // 1: ...
297 // ...
298 // 7: The default directories, normally /lib and /usr/lib.
299 #if defined(AMD64) || defined(_LP64) && (defined(SPARC) || defined(PPC) || defined(S390))
300 #define DEFAULT_LIBPATH "/usr/lib64:/lib64:/lib:/usr/lib"
301 #else
302 #define DEFAULT_LIBPATH "/lib:/usr/lib"
303 #endif
304
305 // Base path of extensions installed on the system.
306 #define SYS_EXT_DIR "/usr/java/packages"
307 #define EXTENSIONS_DIR "/lib/ext"
308
309 // Buffer that fits several sprintfs.
310 // Note that the space for the colon and the trailing null are provided
311 // by the nulls included by the sizeof operator.
312 const size_t bufsize =
313 MAX2((size_t)MAXPATHLEN, // For dll_dir & friends.
314 (size_t)MAXPATHLEN + sizeof(EXTENSIONS_DIR) + sizeof(SYS_EXT_DIR) + sizeof(EXTENSIONS_DIR)); // extensions dir
315 char *buf = (char *)NEW_C_HEAP_ARRAY(char, bufsize, mtInternal);
316
317 // sysclasspath, java_home, dll_dir
318 {
319 char *pslash;
320 os::jvm_path(buf, bufsize);
321
322 // Found the full path to libjvm.so.
323 // Now cut the path to <java_home>/jre if we can.
324 pslash = strrchr(buf, '/');
325 if (pslash != NULL) {
326 *pslash = '\0'; // Get rid of /libjvm.so.
327 }
328 pslash = strrchr(buf, '/');
329 if (pslash != NULL) {
330 *pslash = '\0'; // Get rid of /{client|server|hotspot}.
331 }
332 Arguments::set_dll_dir(buf);
333
334 if (pslash != NULL) {
335 pslash = strrchr(buf, '/');
336 if (pslash != NULL) {
337 *pslash = '\0'; // Get rid of /<arch>.
338 pslash = strrchr(buf, '/');
339 if (pslash != NULL) {
340 *pslash = '\0'; // Get rid of /lib.
341 }
342 }
343 }
344 Arguments::set_java_home(buf);
345 set_boot_path('/', ':');
346 }
347
348 // Where to look for native libraries.
349 //
350 // Note: Due to a legacy implementation, most of the library path
351 // is set in the launcher. This was to accomodate linking restrictions
352 // on legacy Linux implementations (which are no longer supported).
353 // Eventually, all the library path setting will be done here.
354 //
355 // However, to prevent the proliferation of improperly built native
356 // libraries, the new path component /usr/java/packages is added here.
357 // Eventually, all the library path setting will be done here.
358 {
359 // Get the user setting of LD_LIBRARY_PATH, and prepended it. It
360 // should always exist (until the legacy problem cited above is
361 // addressed).
362 const char *v = ::getenv("LD_LIBRARY_PATH");
363 const char *v_colon = ":";
364 if (v == NULL) { v = ""; v_colon = ""; }
365 // That's +1 for the colon and +1 for the trailing '\0'.
366 char *ld_library_path = (char *)NEW_C_HEAP_ARRAY(char,
367 strlen(v) + 1 +
368 sizeof(SYS_EXT_DIR) + sizeof("/lib/") + strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH) + 1,
369 mtInternal);
370 sprintf(ld_library_path, "%s%s" SYS_EXT_DIR "/lib/%s:" DEFAULT_LIBPATH, v, v_colon, cpu_arch);
371 Arguments::set_library_path(ld_library_path);
372 FREE_C_HEAP_ARRAY(char, ld_library_path);
373 }
374
375 // Extensions directories.
376 sprintf(buf, "%s" EXTENSIONS_DIR ":" SYS_EXT_DIR EXTENSIONS_DIR, Arguments::get_java_home());
377 Arguments::set_ext_dirs(buf);
378
379 FREE_C_HEAP_ARRAY(char, buf);
380
381 #undef DEFAULT_LIBPATH
382 #undef SYS_EXT_DIR
383 #undef EXTENSIONS_DIR
384 }
385
386 ////////////////////////////////////////////////////////////////////////////////
387 // breakpoint support
388
389 void os::breakpoint() {
390 BREAKPOINT;
391 }
392
393 extern "C" void breakpoint() {
394 // use debugger to set breakpoint here
395 }
396
397 ////////////////////////////////////////////////////////////////////////////////
398 // signal support
399
400 debug_only(static bool signal_sets_initialized = false);
401 static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs;
402
403 bool os::Linux::is_sig_ignored(int sig) {
404 struct sigaction oact;
405 sigaction(sig, (struct sigaction*)NULL, &oact);
406 void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*, oact.sa_sigaction)
407 : CAST_FROM_FN_PTR(void*, oact.sa_handler);
408 if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN)) {
409 return true;
410 } else {
411 return false;
412 }
413 }
414
415 void os::Linux::signal_sets_init() {
416 // Should also have an assertion stating we are still single-threaded.
417 assert(!signal_sets_initialized, "Already initialized");
418 // Fill in signals that are necessarily unblocked for all threads in
419 // the VM. Currently, we unblock the following signals:
420 // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden
421 // by -Xrs (=ReduceSignalUsage));
422 // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all
423 // other threads. The "ReduceSignalUsage" boolean tells us not to alter
424 // the dispositions or masks wrt these signals.
425 // Programs embedding the VM that want to use the above signals for their
426 // own purposes must, at this time, use the "-Xrs" option to prevent
427 // interference with shutdown hooks and BREAK_SIGNAL thread dumping.
428 // (See bug 4345157, and other related bugs).
429 // In reality, though, unblocking these signals is really a nop, since
430 // these signals are not blocked by default.
431 sigemptyset(&unblocked_sigs);
432 sigemptyset(&allowdebug_blocked_sigs);
433 sigaddset(&unblocked_sigs, SIGILL);
434 sigaddset(&unblocked_sigs, SIGSEGV);
435 sigaddset(&unblocked_sigs, SIGBUS);
436 sigaddset(&unblocked_sigs, SIGFPE);
437 #if defined(PPC64)
438 sigaddset(&unblocked_sigs, SIGTRAP);
439 #endif
440 sigaddset(&unblocked_sigs, SR_signum);
441
442 if (!ReduceSignalUsage) {
443 if (!os::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) {
444 sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL);
445 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL);
446 }
447 if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) {
448 sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL);
449 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL);
450 }
451 if (!os::Linux::is_sig_ignored(SHUTDOWN3_SIGNAL)) {
452 sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL);
453 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN3_SIGNAL);
454 }
455 }
456 // Fill in signals that are blocked by all but the VM thread.
457 sigemptyset(&vm_sigs);
458 if (!ReduceSignalUsage) {
459 sigaddset(&vm_sigs, BREAK_SIGNAL);
460 }
461 debug_only(signal_sets_initialized = true);
462
463 }
464
465 // These are signals that are unblocked while a thread is running Java.
466 // (For some reason, they get blocked by default.)
467 sigset_t* os::Linux::unblocked_signals() {
468 assert(signal_sets_initialized, "Not initialized");
469 return &unblocked_sigs;
470 }
471
472 // These are the signals that are blocked while a (non-VM) thread is
473 // running Java. Only the VM thread handles these signals.
474 sigset_t* os::Linux::vm_signals() {
475 assert(signal_sets_initialized, "Not initialized");
476 return &vm_sigs;
477 }
478
479 // These are signals that are blocked during cond_wait to allow debugger in
480 sigset_t* os::Linux::allowdebug_blocked_signals() {
481 assert(signal_sets_initialized, "Not initialized");
482 return &allowdebug_blocked_sigs;
483 }
484
485 void os::Linux::hotspot_sigmask(Thread* thread) {
486
487 //Save caller's signal mask before setting VM signal mask
488 sigset_t caller_sigmask;
489 pthread_sigmask(SIG_BLOCK, NULL, &caller_sigmask);
490
491 OSThread* osthread = thread->osthread();
492 osthread->set_caller_sigmask(caller_sigmask);
493
494 pthread_sigmask(SIG_UNBLOCK, os::Linux::unblocked_signals(), NULL);
495
496 if (!ReduceSignalUsage) {
497 if (thread->is_VM_thread()) {
498 // Only the VM thread handles BREAK_SIGNAL ...
499 pthread_sigmask(SIG_UNBLOCK, vm_signals(), NULL);
500 } else {
501 // ... all other threads block BREAK_SIGNAL
502 pthread_sigmask(SIG_BLOCK, vm_signals(), NULL);
503 }
504 }
505 }
506
507 //////////////////////////////////////////////////////////////////////////////
508 // detecting pthread library
509
510 void os::Linux::libpthread_init() {
511 // Save glibc and pthread version strings. Note that _CS_GNU_LIBC_VERSION
512 // and _CS_GNU_LIBPTHREAD_VERSION are supported in glibc >= 2.3.2. Use a
513 // generic name for earlier versions.
514 // Define macros here so we can build HotSpot on old systems.
515 #ifndef _CS_GNU_LIBC_VERSION
516 #define _CS_GNU_LIBC_VERSION 2
517 #endif
518 #ifndef _CS_GNU_LIBPTHREAD_VERSION
519 #define _CS_GNU_LIBPTHREAD_VERSION 3
520 #endif
521
522 size_t n = confstr(_CS_GNU_LIBC_VERSION, NULL, 0);
523 if (n > 0) {
524 char *str = (char *)malloc(n, mtInternal);
525 confstr(_CS_GNU_LIBC_VERSION, str, n);
526 os::Linux::set_glibc_version(str);
527 } else {
528 // _CS_GNU_LIBC_VERSION is not supported, try gnu_get_libc_version()
529 static char _gnu_libc_version[32];
530 jio_snprintf(_gnu_libc_version, sizeof(_gnu_libc_version),
531 "glibc %s %s", gnu_get_libc_version(), gnu_get_libc_release());
532 os::Linux::set_glibc_version(_gnu_libc_version);
533 }
534
535 n = confstr(_CS_GNU_LIBPTHREAD_VERSION, NULL, 0);
536 if (n > 0) {
537 char *str = (char *)malloc(n, mtInternal);
538 confstr(_CS_GNU_LIBPTHREAD_VERSION, str, n);
539 // Vanilla RH-9 (glibc 2.3.2) has a bug that confstr() always tells
540 // us "NPTL-0.29" even we are running with LinuxThreads. Check if this
541 // is the case. LinuxThreads has a hard limit on max number of threads.
542 // So sysconf(_SC_THREAD_THREADS_MAX) will return a positive value.
543 // On the other hand, NPTL does not have such a limit, sysconf()
544 // will return -1 and errno is not changed. Check if it is really NPTL.
545 if (strcmp(os::Linux::glibc_version(), "glibc 2.3.2") == 0 &&
546 strstr(str, "NPTL") &&
547 sysconf(_SC_THREAD_THREADS_MAX) > 0) {
548 free(str);
549 os::Linux::set_libpthread_version("linuxthreads");
550 } else {
551 os::Linux::set_libpthread_version(str);
552 }
553 } else {
554 // glibc before 2.3.2 only has LinuxThreads.
555 os::Linux::set_libpthread_version("linuxthreads");
556 }
557
558 if (strstr(libpthread_version(), "NPTL")) {
559 os::Linux::set_is_NPTL();
560 } else {
561 os::Linux::set_is_LinuxThreads();
562 }
563
564 // LinuxThreads have two flavors: floating-stack mode, which allows variable
565 // stack size; and fixed-stack mode. NPTL is always floating-stack.
566 if (os::Linux::is_NPTL() || os::Linux::supports_variable_stack_size()) {
567 os::Linux::set_is_floating_stack();
568 }
569 }
570
571 /////////////////////////////////////////////////////////////////////////////
572 // thread stack
573
574 // Force Linux kernel to expand current thread stack. If "bottom" is close
575 // to the stack guard, caller should block all signals.
576 //
577 // MAP_GROWSDOWN:
578 // A special mmap() flag that is used to implement thread stacks. It tells
579 // kernel that the memory region should extend downwards when needed. This
580 // allows early versions of LinuxThreads to only mmap the first few pages
581 // when creating a new thread. Linux kernel will automatically expand thread
582 // stack as needed (on page faults).
583 //
584 // However, because the memory region of a MAP_GROWSDOWN stack can grow on
585 // demand, if a page fault happens outside an already mapped MAP_GROWSDOWN
586 // region, it's hard to tell if the fault is due to a legitimate stack
587 // access or because of reading/writing non-exist memory (e.g. buffer
588 // overrun). As a rule, if the fault happens below current stack pointer,
589 // Linux kernel does not expand stack, instead a SIGSEGV is sent to the
590 // application (see Linux kernel fault.c).
591 //
592 // This Linux feature can cause SIGSEGV when VM bangs thread stack for
593 // stack overflow detection.
594 //
595 // Newer version of LinuxThreads (since glibc-2.2, or, RH-7.x) and NPTL do
596 // not use this flag. However, the stack of initial thread is not created
597 // by pthread, it is still MAP_GROWSDOWN. Also it's possible (though
598 // unlikely) that user code can create a thread with MAP_GROWSDOWN stack
599 // and then attach the thread to JVM.
600 //
601 // To get around the problem and allow stack banging on Linux, we need to
602 // manually expand thread stack after receiving the SIGSEGV.
603 //
604 // There are two ways to expand thread stack to address "bottom", we used
605 // both of them in JVM before 1.5:
606 // 1. adjust stack pointer first so that it is below "bottom", and then
607 // touch "bottom"
608 // 2. mmap() the page in question
609 //
610 // Now alternate signal stack is gone, it's harder to use 2. For instance,
611 // if current sp is already near the lower end of page 101, and we need to
612 // call mmap() to map page 100, it is possible that part of the mmap() frame
613 // will be placed in page 100. When page 100 is mapped, it is zero-filled.
614 // That will destroy the mmap() frame and cause VM to crash.
615 //
616 // The following code works by adjusting sp first, then accessing the "bottom"
617 // page to force a page fault. Linux kernel will then automatically expand the
618 // stack mapping.
619 //
620 // _expand_stack_to() assumes its frame size is less than page size, which
621 // should always be true if the function is not inlined.
622
623 #if __GNUC__ < 3 // gcc 2.x does not support noinline attribute
624 #define NOINLINE
625 #else
626 #define NOINLINE __attribute__ ((noinline))
627 #endif
628
629 static void _expand_stack_to(address bottom) NOINLINE;
630
631 static void _expand_stack_to(address bottom) {
632 address sp;
633 size_t size;
634 volatile char *p;
635
636 // Adjust bottom to point to the largest address within the same page, it
637 // gives us a one-page buffer if alloca() allocates slightly more memory.
638 bottom = (address)align_size_down((uintptr_t)bottom, os::Linux::page_size());
639 bottom += os::Linux::page_size() - 1;
640
641 // sp might be slightly above current stack pointer; if that's the case, we
642 // will alloca() a little more space than necessary, which is OK. Don't use
643 // os::current_stack_pointer(), as its result can be slightly below current
644 // stack pointer, causing us to not alloca enough to reach "bottom".
645 sp = (address)&sp;
646
647 if (sp > bottom) {
648 size = sp - bottom;
649 p = (volatile char *)alloca(size);
650 assert(p != NULL && p <= (volatile char *)bottom, "alloca problem?");
651 p[0] = '\0';
652 }
653 }
654
655 bool os::Linux::manually_expand_stack(JavaThread * t, address addr) {
656 assert(t!=NULL, "just checking");
657 assert(t->osthread()->expanding_stack(), "expand should be set");
658 assert(t->stack_base() != NULL, "stack_base was not initialized");
659
660 if (addr < t->stack_base() && addr >= t->stack_yellow_zone_base()) {
661 sigset_t mask_all, old_sigset;
662 sigfillset(&mask_all);
663 pthread_sigmask(SIG_SETMASK, &mask_all, &old_sigset);
664 _expand_stack_to(addr);
665 pthread_sigmask(SIG_SETMASK, &old_sigset, NULL);
666 return true;
667 }
668 return false;
669 }
670
671 //////////////////////////////////////////////////////////////////////////////
672 // create new thread
673
674 static address highest_vm_reserved_address();
675
676 // check if it's safe to start a new thread
677 static bool _thread_safety_check(Thread* thread) {
678 if (os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack()) {
679 // Fixed stack LinuxThreads (SuSE Linux/x86, and some versions of Redhat)
680 // Heap is mmap'ed at lower end of memory space. Thread stacks are
681 // allocated (MAP_FIXED) from high address space. Every thread stack
682 // occupies a fixed size slot (usually 2Mbytes, but user can change
683 // it to other values if they rebuild LinuxThreads).
684 //
685 // Problem with MAP_FIXED is that mmap() can still succeed even part of
686 // the memory region has already been mmap'ed. That means if we have too
687 // many threads and/or very large heap, eventually thread stack will
688 // collide with heap.
689 //
690 // Here we try to prevent heap/stack collision by comparing current
691 // stack bottom with the highest address that has been mmap'ed by JVM
692 // plus a safety margin for memory maps created by native code.
693 //
694 // This feature can be disabled by setting ThreadSafetyMargin to 0
695 //
696 if (ThreadSafetyMargin > 0) {
697 address stack_bottom = os::current_stack_base() - os::current_stack_size();
698
699 // not safe if our stack extends below the safety margin
700 return stack_bottom - ThreadSafetyMargin >= highest_vm_reserved_address();
701 } else {
702 return true;
703 }
704 } else {
705 // Floating stack LinuxThreads or NPTL:
706 // Unlike fixed stack LinuxThreads, thread stacks are not MAP_FIXED. When
707 // there's not enough space left, pthread_create() will fail. If we come
708 // here, that means enough space has been reserved for stack.
709 return true;
710 }
711 }
712
713 // Thread start routine for all newly created threads
714 static void *java_start(Thread *thread) {
715 // Try to randomize the cache line index of hot stack frames.
716 // This helps when threads of the same stack traces evict each other's
717 // cache lines. The threads can be either from the same JVM instance, or
718 // from different JVM instances. The benefit is especially true for
719 // processors with hyperthreading technology.
720 static int counter = 0;
721 int pid = os::current_process_id();
722 alloca(((pid ^ counter++) & 7) * 128);
723
724 ThreadLocalStorage::set_thread(thread);
725
726 OSThread* osthread = thread->osthread();
727 Monitor* sync = osthread->startThread_lock();
728
729 // non floating stack LinuxThreads needs extra check, see above
730 if (!_thread_safety_check(thread)) {
731 // notify parent thread
732 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
733 osthread->set_state(ZOMBIE);
734 sync->notify_all();
735 return NULL;
736 }
737
738 // thread_id is kernel thread id (similar to Solaris LWP id)
739 osthread->set_thread_id(os::Linux::gettid());
740
741 if (UseNUMA) {
742 int lgrp_id = os::numa_get_group_id();
743 if (lgrp_id != -1) {
744 thread->set_lgrp_id(lgrp_id);
745 }
746 }
747 // initialize signal mask for this thread
748 os::Linux::hotspot_sigmask(thread);
749
750 // initialize floating point control register
751 os::Linux::init_thread_fpu_state();
752
753 // handshaking with parent thread
754 {
755 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
756
757 // notify parent thread
758 osthread->set_state(INITIALIZED);
759 sync->notify_all();
760
761 // wait until os::start_thread()
762 while (osthread->get_state() == INITIALIZED) {
763 sync->wait(Mutex::_no_safepoint_check_flag);
764 }
765 }
766
767 // call one more level start routine
768 thread->run();
769
770 return 0;
771 }
772
773 bool os::create_thread(Thread* thread, ThreadType thr_type,
774 size_t stack_size) {
775 assert(thread->osthread() == NULL, "caller responsible");
776
777 // Allocate the OSThread object
778 OSThread* osthread = new OSThread(NULL, NULL);
779 if (osthread == NULL) {
780 return false;
781 }
782
783 // set the correct thread state
784 osthread->set_thread_type(thr_type);
785
786 // Initial state is ALLOCATED but not INITIALIZED
787 osthread->set_state(ALLOCATED);
788
789 thread->set_osthread(osthread);
790
791 // init thread attributes
792 pthread_attr_t attr;
793 pthread_attr_init(&attr);
794 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
795
796 // stack size
797 if (os::Linux::supports_variable_stack_size()) {
798 // calculate stack size if it's not specified by caller
799 if (stack_size == 0) {
800 stack_size = os::Linux::default_stack_size(thr_type);
801
802 switch (thr_type) {
803 case os::java_thread:
804 // Java threads use ThreadStackSize which default value can be
805 // changed with the flag -Xss
806 assert(JavaThread::stack_size_at_create() > 0, "this should be set");
807 stack_size = JavaThread::stack_size_at_create();
808 break;
809 case os::compiler_thread:
810 if (CompilerThreadStackSize > 0) {
811 stack_size = (size_t)(CompilerThreadStackSize * K);
812 break;
813 } // else fall through:
814 // use VMThreadStackSize if CompilerThreadStackSize is not defined
815 case os::vm_thread:
816 case os::pgc_thread:
817 case os::cgc_thread:
818 case os::watcher_thread:
819 if (VMThreadStackSize > 0) stack_size = (size_t)(VMThreadStackSize * K);
820 break;
821 }
822 }
823
824 stack_size = MAX2(stack_size, os::Linux::min_stack_allowed);
825 pthread_attr_setstacksize(&attr, stack_size);
826 } else {
827 // let pthread_create() pick the default value.
828 }
829
830 // glibc guard page
831 pthread_attr_setguardsize(&attr, os::Linux::default_guard_size(thr_type));
832
833 ThreadState state;
834
835 {
836 // Serialize thread creation if we are running with fixed stack LinuxThreads
837 bool lock = os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack();
838 if (lock) {
839 os::Linux::createThread_lock()->lock_without_safepoint_check();
840 }
841
842 pthread_t tid;
843 int ret = pthread_create(&tid, &attr, (void* (*)(void*)) java_start, thread);
844
845 pthread_attr_destroy(&attr);
846
847 if (ret != 0) {
848 if (PrintMiscellaneous && (Verbose || WizardMode)) {
849 perror("pthread_create()");
850 }
851 // Need to clean up stuff we've allocated so far
852 thread->set_osthread(NULL);
853 delete osthread;
854 if (lock) os::Linux::createThread_lock()->unlock();
855 return false;
856 }
857
858 // Store pthread info into the OSThread
859 osthread->set_pthread_id(tid);
860
861 // Wait until child thread is either initialized or aborted
862 {
863 Monitor* sync_with_child = osthread->startThread_lock();
864 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
865 while ((state = osthread->get_state()) == ALLOCATED) {
866 sync_with_child->wait(Mutex::_no_safepoint_check_flag);
867 }
868 }
869
870 if (lock) {
871 os::Linux::createThread_lock()->unlock();
872 }
873 }
874
875 // Aborted due to thread limit being reached
876 if (state == ZOMBIE) {
877 thread->set_osthread(NULL);
878 delete osthread;
879 return false;
880 }
881
882 // The thread is returned suspended (in state INITIALIZED),
883 // and is started higher up in the call chain
884 assert(state == INITIALIZED, "race condition");
885 return true;
886 }
887
888 /////////////////////////////////////////////////////////////////////////////
889 // attach existing thread
890
891 // bootstrap the main thread
892 bool os::create_main_thread(JavaThread* thread) {
893 assert(os::Linux::_main_thread == pthread_self(), "should be called inside main thread");
894 return create_attached_thread(thread);
895 }
896
897 bool os::create_attached_thread(JavaThread* thread) {
898 #ifdef ASSERT
899 thread->verify_not_published();
900 #endif
901
902 // Allocate the OSThread object
903 OSThread* osthread = new OSThread(NULL, NULL);
904
905 if (osthread == NULL) {
906 return false;
907 }
908
909 // Store pthread info into the OSThread
910 osthread->set_thread_id(os::Linux::gettid());
911 osthread->set_pthread_id(::pthread_self());
912
913 // initialize floating point control register
914 os::Linux::init_thread_fpu_state();
915
916 // Initial thread state is RUNNABLE
917 osthread->set_state(RUNNABLE);
918
919 thread->set_osthread(osthread);
920
921 if (UseNUMA) {
922 int lgrp_id = os::numa_get_group_id();
923 if (lgrp_id != -1) {
924 thread->set_lgrp_id(lgrp_id);
925 }
926 }
927
928 if (os::Linux::is_initial_thread()) {
929 // If current thread is initial thread, its stack is mapped on demand,
930 // see notes about MAP_GROWSDOWN. Here we try to force kernel to map
931 // the entire stack region to avoid SEGV in stack banging.
932 // It is also useful to get around the heap-stack-gap problem on SuSE
933 // kernel (see 4821821 for details). We first expand stack to the top
934 // of yellow zone, then enable stack yellow zone (order is significant,
935 // enabling yellow zone first will crash JVM on SuSE Linux), so there
936 // is no gap between the last two virtual memory regions.
937
938 JavaThread *jt = (JavaThread *)thread;
939 address addr = jt->stack_yellow_zone_base();
940 assert(addr != NULL, "initialization problem?");
941 assert(jt->stack_available(addr) > 0, "stack guard should not be enabled");
942
943 osthread->set_expanding_stack();
944 os::Linux::manually_expand_stack(jt, addr);
945 osthread->clear_expanding_stack();
946 }
947
948 // initialize signal mask for this thread
949 // and save the caller's signal mask
950 os::Linux::hotspot_sigmask(thread);
951
952 return true;
953 }
954
955 void os::pd_start_thread(Thread* thread) {
956 OSThread * osthread = thread->osthread();
957 assert(osthread->get_state() != INITIALIZED, "just checking");
958 Monitor* sync_with_child = osthread->startThread_lock();
959 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
960 sync_with_child->notify();
961 }
962
963 // Free Linux resources related to the OSThread
964 void os::free_thread(OSThread* osthread) {
965 assert(osthread != NULL, "osthread not set");
966
967 if (Thread::current()->osthread() == osthread) {
968 // Restore caller's signal mask
969 sigset_t sigmask = osthread->caller_sigmask();
970 pthread_sigmask(SIG_SETMASK, &sigmask, NULL);
971 }
972
973 delete osthread;
974 }
975
976 //////////////////////////////////////////////////////////////////////////////
977 // thread local storage
978
979 // Restore the thread pointer if the destructor is called. This is in case
980 // someone from JNI code sets up a destructor with pthread_key_create to run
981 // detachCurrentThread on thread death. Unless we restore the thread pointer we
982 // will hang or crash. When detachCurrentThread is called the key will be set
983 // to null and we will not be called again. If detachCurrentThread is never
984 // called we could loop forever depending on the pthread implementation.
985 static void restore_thread_pointer(void* p) {
986 Thread* thread = (Thread*) p;
987 os::thread_local_storage_at_put(ThreadLocalStorage::thread_index(), thread);
988 }
989
990 int os::allocate_thread_local_storage() {
991 pthread_key_t key;
992 int rslt = pthread_key_create(&key, restore_thread_pointer);
993 assert(rslt == 0, "cannot allocate thread local storage");
994 return (int)key;
995 }
996
997 // Note: This is currently not used by VM, as we don't destroy TLS key
998 // on VM exit.
999 void os::free_thread_local_storage(int index) {
1000 int rslt = pthread_key_delete((pthread_key_t)index);
1001 assert(rslt == 0, "invalid index");
1002 }
1003
1004 void os::thread_local_storage_at_put(int index, void* value) {
1005 int rslt = pthread_setspecific((pthread_key_t)index, value);
1006 assert(rslt == 0, "pthread_setspecific failed");
1007 }
1008
1009 extern "C" Thread* get_thread() {
1010 return ThreadLocalStorage::thread();
1011 }
1012
1013 //////////////////////////////////////////////////////////////////////////////
1014 // initial thread
1015
1016 // Check if current thread is the initial thread, similar to Solaris thr_main.
1017 bool os::Linux::is_initial_thread(void) {
1018 char dummy;
1019 // If called before init complete, thread stack bottom will be null.
1020 // Can be called if fatal error occurs before initialization.
1021 if (initial_thread_stack_bottom() == NULL) return false;
1022 assert(initial_thread_stack_bottom() != NULL &&
1023 initial_thread_stack_size() != 0,
1024 "os::init did not locate initial thread's stack region");
1025 if ((address)&dummy >= initial_thread_stack_bottom() &&
1026 (address)&dummy < initial_thread_stack_bottom() + initial_thread_stack_size()) {
1027 return true;
1028 } else {
1029 return false;
1030 }
1031 }
1032
1033 // Find the virtual memory area that contains addr
1034 static bool find_vma(address addr, address* vma_low, address* vma_high) {
1035 FILE *fp = fopen("/proc/self/maps", "r");
1036 if (fp) {
1037 address low, high;
1038 while (!feof(fp)) {
1039 if (fscanf(fp, "%p-%p", &low, &high) == 2) {
1040 if (low <= addr && addr < high) {
1041 if (vma_low) *vma_low = low;
1042 if (vma_high) *vma_high = high;
1043 fclose(fp);
1044 return true;
1045 }
1046 }
1047 for (;;) {
1048 int ch = fgetc(fp);
1049 if (ch == EOF || ch == (int)'\n') break;
1050 }
1051 }
1052 fclose(fp);
1053 }
1054 return false;
1055 }
1056
1057 // Locate initial thread stack. This special handling of initial thread stack
1058 // is needed because pthread_getattr_np() on most (all?) Linux distros returns
1059 // bogus value for initial thread.
1060 void os::Linux::capture_initial_stack(size_t max_size) {
1061 // stack size is the easy part, get it from RLIMIT_STACK
1062 size_t stack_size;
1063 struct rlimit rlim;
1064 getrlimit(RLIMIT_STACK, &rlim);
1065 stack_size = rlim.rlim_cur;
1066
1067 // 6308388: a bug in ld.so will relocate its own .data section to the
1068 // lower end of primordial stack; reduce ulimit -s value a little bit
1069 // so we won't install guard page on ld.so's data section.
1070 stack_size -= 2 * page_size();
1071
1072 // 4441425: avoid crash with "unlimited" stack size on SuSE 7.1 or Redhat
1073 // 7.1, in both cases we will get 2G in return value.
1074 // 4466587: glibc 2.2.x compiled w/o "--enable-kernel=2.4.0" (RH 7.0,
1075 // SuSE 7.2, Debian) can not handle alternate signal stack correctly
1076 // for initial thread if its stack size exceeds 6M. Cap it at 2M,
1077 // in case other parts in glibc still assumes 2M max stack size.
1078 // FIXME: alt signal stack is gone, maybe we can relax this constraint?
1079 // Problem still exists RH7.2 (IA64 anyway) but 2MB is a little small
1080 if (stack_size > 2 * K * K IA64_ONLY(*2)) {
1081 stack_size = 2 * K * K IA64_ONLY(*2);
1082 }
1083 // Try to figure out where the stack base (top) is. This is harder.
1084 //
1085 // When an application is started, glibc saves the initial stack pointer in
1086 // a global variable "__libc_stack_end", which is then used by system
1087 // libraries. __libc_stack_end should be pretty close to stack top. The
1088 // variable is available since the very early days. However, because it is
1089 // a private interface, it could disappear in the future.
1090 //
1091 // Linux kernel saves start_stack information in /proc/<pid>/stat. Similar
1092 // to __libc_stack_end, it is very close to stack top, but isn't the real
1093 // stack top. Note that /proc may not exist if VM is running as a chroot
1094 // program, so reading /proc/<pid>/stat could fail. Also the contents of
1095 // /proc/<pid>/stat could change in the future (though unlikely).
1096 //
1097 // We try __libc_stack_end first. If that doesn't work, look for
1098 // /proc/<pid>/stat. If neither of them works, we use current stack pointer
1099 // as a hint, which should work well in most cases.
1100
1101 uintptr_t stack_start;
1102
1103 // try __libc_stack_end first
1104 uintptr_t *p = (uintptr_t *)dlsym(RTLD_DEFAULT, "__libc_stack_end");
1105 if (p && *p) {
1106 stack_start = *p;
1107 } else {
1108 // see if we can get the start_stack field from /proc/self/stat
1109 FILE *fp;
1110 int pid;
1111 char state;
1112 int ppid;
1113 int pgrp;
1114 int session;
1115 int nr;
1116 int tpgrp;
1117 unsigned long flags;
1118 unsigned long minflt;
1119 unsigned long cminflt;
1120 unsigned long majflt;
1121 unsigned long cmajflt;
1122 unsigned long utime;
1123 unsigned long stime;
1124 long cutime;
1125 long cstime;
1126 long prio;
1127 long nice;
1128 long junk;
1129 long it_real;
1130 uintptr_t start;
1131 uintptr_t vsize;
1132 intptr_t rss;
1133 uintptr_t rsslim;
1134 uintptr_t scodes;
1135 uintptr_t ecode;
1136 int i;
1137
1138 // Figure what the primordial thread stack base is. Code is inspired
1139 // by email from Hans Boehm. /proc/self/stat begins with current pid,
1140 // followed by command name surrounded by parentheses, state, etc.
1141 char stat[2048];
1142 int statlen;
1143
1144 fp = fopen("/proc/self/stat", "r");
1145 if (fp) {
1146 statlen = fread(stat, 1, 2047, fp);
1147 stat[statlen] = '\0';
1148 fclose(fp);
1149
1150 // Skip pid and the command string. Note that we could be dealing with
1151 // weird command names, e.g. user could decide to rename java launcher
1152 // to "java 1.4.2 :)", then the stat file would look like
1153 // 1234 (java 1.4.2 :)) R ... ...
1154 // We don't really need to know the command string, just find the last
1155 // occurrence of ")" and then start parsing from there. See bug 4726580.
1156 char * s = strrchr(stat, ')');
1157
1158 i = 0;
1159 if (s) {
1160 // Skip blank chars
1161 do { s++; } while (s && isspace(*s));
1162
1163 #define _UFM UINTX_FORMAT
1164 #define _DFM INTX_FORMAT
1165
1166 // 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2
1167 // 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
1168 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,
1169 &state, // 3 %c
1170 &ppid, // 4 %d
1171 &pgrp, // 5 %d
1172 &session, // 6 %d
1173 &nr, // 7 %d
1174 &tpgrp, // 8 %d
1175 &flags, // 9 %lu
1176 &minflt, // 10 %lu
1177 &cminflt, // 11 %lu
1178 &majflt, // 12 %lu
1179 &cmajflt, // 13 %lu
1180 &utime, // 14 %lu
1181 &stime, // 15 %lu
1182 &cutime, // 16 %ld
1183 &cstime, // 17 %ld
1184 &prio, // 18 %ld
1185 &nice, // 19 %ld
1186 &junk, // 20 %ld
1187 &it_real, // 21 %ld
1188 &start, // 22 UINTX_FORMAT
1189 &vsize, // 23 UINTX_FORMAT
1190 &rss, // 24 INTX_FORMAT
1191 &rsslim, // 25 UINTX_FORMAT
1192 &scodes, // 26 UINTX_FORMAT
1193 &ecode, // 27 UINTX_FORMAT
1194 &stack_start); // 28 UINTX_FORMAT
1195 }
1196
1197 #undef _UFM
1198 #undef _DFM
1199
1200 if (i != 28 - 2) {
1201 assert(false, "Bad conversion from /proc/self/stat");
1202 // product mode - assume we are the initial thread, good luck in the
1203 // embedded case.
1204 warning("Can't detect initial thread stack location - bad conversion");
1205 stack_start = (uintptr_t) &rlim;
1206 }
1207 } else {
1208 // For some reason we can't open /proc/self/stat (for example, running on
1209 // FreeBSD with a Linux emulator, or inside chroot), this should work for
1210 // most cases, so don't abort:
1211 warning("Can't detect initial thread stack location - no /proc/self/stat");
1212 stack_start = (uintptr_t) &rlim;
1213 }
1214 }
1215
1216 // Now we have a pointer (stack_start) very close to the stack top, the
1217 // next thing to do is to figure out the exact location of stack top. We
1218 // can find out the virtual memory area that contains stack_start by
1219 // reading /proc/self/maps, it should be the last vma in /proc/self/maps,
1220 // and its upper limit is the real stack top. (again, this would fail if
1221 // running inside chroot, because /proc may not exist.)
1222
1223 uintptr_t stack_top;
1224 address low, high;
1225 if (find_vma((address)stack_start, &low, &high)) {
1226 // success, "high" is the true stack top. (ignore "low", because initial
1227 // thread stack grows on demand, its real bottom is high - RLIMIT_STACK.)
1228 stack_top = (uintptr_t)high;
1229 } else {
1230 // failed, likely because /proc/self/maps does not exist
1231 warning("Can't detect initial thread stack location - find_vma failed");
1232 // best effort: stack_start is normally within a few pages below the real
1233 // stack top, use it as stack top, and reduce stack size so we won't put
1234 // guard page outside stack.
1235 stack_top = stack_start;
1236 stack_size -= 16 * page_size();
1237 }
1238
1239 // stack_top could be partially down the page so align it
1240 stack_top = align_size_up(stack_top, page_size());
1241
1242 if (max_size && stack_size > max_size) {
1243 _initial_thread_stack_size = max_size;
1244 } else {
1245 _initial_thread_stack_size = stack_size;
1246 }
1247
1248 _initial_thread_stack_size = align_size_down(_initial_thread_stack_size, page_size());
1249 _initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size;
1250 }
1251
1252 ////////////////////////////////////////////////////////////////////////////////
1253 // time support
1254
1255 // Time since start-up in seconds to a fine granularity.
1256 // Used by VMSelfDestructTimer and the MemProfiler.
1257 double os::elapsedTime() {
1258
1259 return ((double)os::elapsed_counter()) / os::elapsed_frequency(); // nanosecond resolution
1260 }
1261
1262 jlong os::elapsed_counter() {
1263 return javaTimeNanos() - initial_time_count;
1264 }
1265
1266 jlong os::elapsed_frequency() {
1267 return NANOSECS_PER_SEC; // nanosecond resolution
1268 }
1269
1270 bool os::supports_vtime() { return true; }
1271 bool os::enable_vtime() { return false; }
1272 bool os::vtime_enabled() { return false; }
1273
1274 double os::elapsedVTime() {
1275 struct rusage usage;
1276 int retval = getrusage(RUSAGE_THREAD, &usage);
1277 if (retval == 0) {
1278 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);
1279 } else {
1280 // better than nothing, but not much
1281 return elapsedTime();
1282 }
1283 }
1284
1285 jlong os::javaTimeMillis() {
1286 timeval time;
1287 int status = gettimeofday(&time, NULL);
1288 assert(status != -1, "linux error");
1289 return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000);
1290 }
1291
1292 void os::javaTimeSystemUTC(jlong &seconds, jlong &nanos) {
1293 timeval time;
1294 int status = gettimeofday(&time, NULL);
1295 assert(status != -1, "linux error");
1296 seconds = jlong(time.tv_sec);
1297 nanos = jlong(time.tv_usec) * 1000;
1298 }
1299
1300
1301 #ifndef CLOCK_MONOTONIC
1302 #define CLOCK_MONOTONIC (1)
1303 #endif
1304
1305 void os::Linux::clock_init() {
1306 // we do dlopen's in this particular order due to bug in linux
1307 // dynamical loader (see 6348968) leading to crash on exit
1308 void* handle = dlopen("librt.so.1", RTLD_LAZY);
1309 if (handle == NULL) {
1310 handle = dlopen("librt.so", RTLD_LAZY);
1311 }
1312
1313 if (handle) {
1314 int (*clock_getres_func)(clockid_t, struct timespec*) =
1315 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres");
1316 int (*clock_gettime_func)(clockid_t, struct timespec*) =
1317 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime");
1318 if (clock_getres_func && clock_gettime_func) {
1319 // See if monotonic clock is supported by the kernel. Note that some
1320 // early implementations simply return kernel jiffies (updated every
1321 // 1/100 or 1/1000 second). It would be bad to use such a low res clock
1322 // for nano time (though the monotonic property is still nice to have).
1323 // It's fixed in newer kernels, however clock_getres() still returns
1324 // 1/HZ. We check if clock_getres() works, but will ignore its reported
1325 // resolution for now. Hopefully as people move to new kernels, this
1326 // won't be a problem.
1327 struct timespec res;
1328 struct timespec tp;
1329 if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 &&
1330 clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) {
1331 // yes, monotonic clock is supported
1332 _clock_gettime = clock_gettime_func;
1333 return;
1334 } else {
1335 // close librt if there is no monotonic clock
1336 dlclose(handle);
1337 }
1338 }
1339 }
1340 warning("No monotonic clock was available - timed services may " \
1341 "be adversely affected if the time-of-day clock changes");
1342 }
1343
1344 #ifndef SYS_clock_getres
1345 #if defined(IA32) || defined(AMD64)
1346 #define SYS_clock_getres IA32_ONLY(266) AMD64_ONLY(229)
1347 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y)
1348 #else
1349 #warning "SYS_clock_getres not defined for this platform, disabling fast_thread_cpu_time"
1350 #define sys_clock_getres(x,y) -1
1351 #endif
1352 #else
1353 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y)
1354 #endif
1355
1356 void os::Linux::fast_thread_clock_init() {
1357 if (!UseLinuxPosixThreadCPUClocks) {
1358 return;
1359 }
1360 clockid_t clockid;
1361 struct timespec tp;
1362 int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) =
1363 (int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid");
1364
1365 // Switch to using fast clocks for thread cpu time if
1366 // the sys_clock_getres() returns 0 error code.
1367 // Note, that some kernels may support the current thread
1368 // clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks
1369 // returned by the pthread_getcpuclockid().
1370 // If the fast Posix clocks are supported then the sys_clock_getres()
1371 // must return at least tp.tv_sec == 0 which means a resolution
1372 // better than 1 sec. This is extra check for reliability.
1373
1374 if (pthread_getcpuclockid_func &&
1375 pthread_getcpuclockid_func(_main_thread, &clockid) == 0 &&
1376 sys_clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) {
1377 _supports_fast_thread_cpu_time = true;
1378 _pthread_getcpuclockid = pthread_getcpuclockid_func;
1379 }
1380 }
1381
1382 jlong os::javaTimeNanos() {
1383 if (os::supports_monotonic_clock()) {
1384 struct timespec tp;
1385 int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp);
1386 assert(status == 0, "gettime error");
1387 jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec);
1388 return result;
1389 } else {
1390 timeval time;
1391 int status = gettimeofday(&time, NULL);
1392 assert(status != -1, "linux error");
1393 jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec);
1394 return 1000 * usecs;
1395 }
1396 }
1397
1398 void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) {
1399 if (os::supports_monotonic_clock()) {
1400 info_ptr->max_value = ALL_64_BITS;
1401
1402 // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past
1403 info_ptr->may_skip_backward = false; // not subject to resetting or drifting
1404 info_ptr->may_skip_forward = false; // not subject to resetting or drifting
1405 } else {
1406 // gettimeofday - based on time in seconds since the Epoch thus does not wrap
1407 info_ptr->max_value = ALL_64_BITS;
1408
1409 // gettimeofday is a real time clock so it skips
1410 info_ptr->may_skip_backward = true;
1411 info_ptr->may_skip_forward = true;
1412 }
1413
1414 info_ptr->kind = JVMTI_TIMER_ELAPSED; // elapsed not CPU time
1415 }
1416
1417 // Return the real, user, and system times in seconds from an
1418 // arbitrary fixed point in the past.
1419 bool os::getTimesSecs(double* process_real_time,
1420 double* process_user_time,
1421 double* process_system_time) {
1422 struct tms ticks;
1423 clock_t real_ticks = times(&ticks);
1424
1425 if (real_ticks == (clock_t) (-1)) {
1426 return false;
1427 } else {
1428 double ticks_per_second = (double) clock_tics_per_sec;
1429 *process_user_time = ((double) ticks.tms_utime) / ticks_per_second;
1430 *process_system_time = ((double) ticks.tms_stime) / ticks_per_second;
1431 *process_real_time = ((double) real_ticks) / ticks_per_second;
1432
1433 return true;
1434 }
1435 }
1436
1437
1438 char * os::local_time_string(char *buf, size_t buflen) {
1439 struct tm t;
1440 time_t long_time;
1441 time(&long_time);
1442 localtime_r(&long_time, &t);
1443 jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d",
1444 t.tm_year + 1900, t.tm_mon + 1, t.tm_mday,
1445 t.tm_hour, t.tm_min, t.tm_sec);
1446 return buf;
1447 }
1448
1449 struct tm* os::localtime_pd(const time_t* clock, struct tm* res) {
1450 return localtime_r(clock, res);
1451 }
1452
1453 ////////////////////////////////////////////////////////////////////////////////
1454 // runtime exit support
1455
1456 // Note: os::shutdown() might be called very early during initialization, or
1457 // called from signal handler. Before adding something to os::shutdown(), make
1458 // sure it is async-safe and can handle partially initialized VM.
1459 void os::shutdown() {
1460
1461 // allow PerfMemory to attempt cleanup of any persistent resources
1462 perfMemory_exit();
1463
1464 // needs to remove object in file system
1465 AttachListener::abort();
1466
1467 // flush buffered output, finish log files
1468 ostream_abort();
1469
1470 // Check for abort hook
1471 abort_hook_t abort_hook = Arguments::abort_hook();
1472 if (abort_hook != NULL) {
1473 abort_hook();
1474 }
1475
1476 }
1477
1478 // Note: os::abort() might be called very early during initialization, or
1479 // called from signal handler. Before adding something to os::abort(), make
1480 // sure it is async-safe and can handle partially initialized VM.
1481 void os::abort(bool dump_core) {
1482 abort(dump_core, NULL, NULL);
1483 }
1484
1485 void os::abort(bool dump_core, void* siginfo, void* context) {
1486 os::shutdown();
1487 if (dump_core) {
1488 #ifndef PRODUCT
1489 fdStream out(defaultStream::output_fd());
1490 out.print_raw("Current thread is ");
1491 char buf[16];
1492 jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id());
1493 out.print_raw_cr(buf);
1494 out.print_raw_cr("Dumping core ...");
1495 #endif
1496 ::abort(); // dump core
1497 }
1498
1499 ::exit(1);
1500 }
1501
1502 // Die immediately, no exit hook, no abort hook, no cleanup.
1503 void os::die() {
1504 // _exit() on LinuxThreads only kills current thread
1505 ::abort();
1506 }
1507
1508
1509 // This method is a copy of JDK's sysGetLastErrorString
1510 // from src/solaris/hpi/src/system_md.c
1511
1512 size_t os::lasterror(char *buf, size_t len) {
1513 if (errno == 0) return 0;
1514
1515 const char *s = ::strerror(errno);
1516 size_t n = ::strlen(s);
1517 if (n >= len) {
1518 n = len - 1;
1519 }
1520 ::strncpy(buf, s, n);
1521 buf[n] = '\0';
1522 return n;
1523 }
1524
1525 intx os::current_thread_id() { return (intx)pthread_self(); }
1526 int os::current_process_id() {
1527
1528 // Under the old linux thread library, linux gives each thread
1529 // its own process id. Because of this each thread will return
1530 // a different pid if this method were to return the result
1531 // of getpid(2). Linux provides no api that returns the pid
1532 // of the launcher thread for the vm. This implementation
1533 // returns a unique pid, the pid of the launcher thread
1534 // that starts the vm 'process'.
1535
1536 // Under the NPTL, getpid() returns the same pid as the
1537 // launcher thread rather than a unique pid per thread.
1538 // Use gettid() if you want the old pre NPTL behaviour.
1539
1540 // if you are looking for the result of a call to getpid() that
1541 // returns a unique pid for the calling thread, then look at the
1542 // OSThread::thread_id() method in osThread_linux.hpp file
1543
1544 return (int)(_initial_pid ? _initial_pid : getpid());
1545 }
1546
1547 // DLL functions
1548
1549 const char* os::dll_file_extension() { return ".so"; }
1550
1551 // This must be hard coded because it's the system's temporary
1552 // directory not the java application's temp directory, ala java.io.tmpdir.
1553 const char* os::get_temp_directory() { return "/tmp"; }
1554
1555 static bool file_exists(const char* filename) {
1556 struct stat statbuf;
1557 if (filename == NULL || strlen(filename) == 0) {
1558 return false;
1559 }
1560 return os::stat(filename, &statbuf) == 0;
1561 }
1562
1563 bool os::dll_build_name(char* buffer, size_t buflen,
1564 const char* pname, const char* fname) {
1565 bool retval = false;
1566 // Copied from libhpi
1567 const size_t pnamelen = pname ? strlen(pname) : 0;
1568
1569 // Return error on buffer overflow.
1570 if (pnamelen + strlen(fname) + 10 > (size_t) buflen) {
1571 return retval;
1572 }
1573
1574 if (pnamelen == 0) {
1575 snprintf(buffer, buflen, "lib%s.so", fname);
1576 retval = true;
1577 } else if (strchr(pname, *os::path_separator()) != NULL) {
1578 int n;
1579 char** pelements = split_path(pname, &n);
1580 if (pelements == NULL) {
1581 return false;
1582 }
1583 for (int i = 0; i < n; i++) {
1584 // Really shouldn't be NULL, but check can't hurt
1585 if (pelements[i] == NULL || strlen(pelements[i]) == 0) {
1586 continue; // skip the empty path values
1587 }
1588 snprintf(buffer, buflen, "%s/lib%s.so", pelements[i], fname);
1589 if (file_exists(buffer)) {
1590 retval = true;
1591 break;
1592 }
1593 }
1594 // release the storage
1595 for (int i = 0; i < n; i++) {
1596 if (pelements[i] != NULL) {
1597 FREE_C_HEAP_ARRAY(char, pelements[i]);
1598 }
1599 }
1600 if (pelements != NULL) {
1601 FREE_C_HEAP_ARRAY(char*, pelements);
1602 }
1603 } else {
1604 snprintf(buffer, buflen, "%s/lib%s.so", pname, fname);
1605 retval = true;
1606 }
1607 return retval;
1608 }
1609
1610 // check if addr is inside libjvm.so
1611 bool os::address_is_in_vm(address addr) {
1612 static address libjvm_base_addr;
1613 Dl_info dlinfo;
1614
1615 if (libjvm_base_addr == NULL) {
1616 if (dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo) != 0) {
1617 libjvm_base_addr = (address)dlinfo.dli_fbase;
1618 }
1619 assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm");
1620 }
1621
1622 if (dladdr((void *)addr, &dlinfo) != 0) {
1623 if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true;
1624 }
1625
1626 return false;
1627 }
1628
1629 bool os::dll_address_to_function_name(address addr, char *buf,
1630 int buflen, int *offset) {
1631 // buf is not optional, but offset is optional
1632 assert(buf != NULL, "sanity check");
1633
1634 Dl_info dlinfo;
1635
1636 if (dladdr((void*)addr, &dlinfo) != 0) {
1637 // see if we have a matching symbol
1638 if (dlinfo.dli_saddr != NULL && dlinfo.dli_sname != NULL) {
1639 if (!Decoder::demangle(dlinfo.dli_sname, buf, buflen)) {
1640 jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname);
1641 }
1642 if (offset != NULL) *offset = addr - (address)dlinfo.dli_saddr;
1643 return true;
1644 }
1645 // no matching symbol so try for just file info
1646 if (dlinfo.dli_fname != NULL && dlinfo.dli_fbase != NULL) {
1647 if (Decoder::decode((address)(addr - (address)dlinfo.dli_fbase),
1648 buf, buflen, offset, dlinfo.dli_fname)) {
1649 return true;
1650 }
1651 }
1652 }
1653
1654 buf[0] = '\0';
1655 if (offset != NULL) *offset = -1;
1656 return false;
1657 }
1658
1659 struct _address_to_library_name {
1660 address addr; // input : memory address
1661 size_t buflen; // size of fname
1662 char* fname; // output: library name
1663 address base; // library base addr
1664 };
1665
1666 static int address_to_library_name_callback(struct dl_phdr_info *info,
1667 size_t size, void *data) {
1668 int i;
1669 bool found = false;
1670 address libbase = NULL;
1671 struct _address_to_library_name * d = (struct _address_to_library_name *)data;
1672
1673 // iterate through all loadable segments
1674 for (i = 0; i < info->dlpi_phnum; i++) {
1675 address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr);
1676 if (info->dlpi_phdr[i].p_type == PT_LOAD) {
1677 // base address of a library is the lowest address of its loaded
1678 // segments.
1679 if (libbase == NULL || libbase > segbase) {
1680 libbase = segbase;
1681 }
1682 // see if 'addr' is within current segment
1683 if (segbase <= d->addr &&
1684 d->addr < segbase + info->dlpi_phdr[i].p_memsz) {
1685 found = true;
1686 }
1687 }
1688 }
1689
1690 // dlpi_name is NULL or empty if the ELF file is executable, return 0
1691 // so dll_address_to_library_name() can fall through to use dladdr() which
1692 // can figure out executable name from argv[0].
1693 if (found && info->dlpi_name && info->dlpi_name[0]) {
1694 d->base = libbase;
1695 if (d->fname) {
1696 jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name);
1697 }
1698 return 1;
1699 }
1700 return 0;
1701 }
1702
1703 bool os::dll_address_to_library_name(address addr, char* buf,
1704 int buflen, int* offset) {
1705 // buf is not optional, but offset is optional
1706 assert(buf != NULL, "sanity check");
1707
1708 Dl_info dlinfo;
1709 struct _address_to_library_name data;
1710
1711 // There is a bug in old glibc dladdr() implementation that it could resolve
1712 // to wrong library name if the .so file has a base address != NULL. Here
1713 // we iterate through the program headers of all loaded libraries to find
1714 // out which library 'addr' really belongs to. This workaround can be
1715 // removed once the minimum requirement for glibc is moved to 2.3.x.
1716 data.addr = addr;
1717 data.fname = buf;
1718 data.buflen = buflen;
1719 data.base = NULL;
1720 int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data);
1721
1722 if (rslt) {
1723 // buf already contains library name
1724 if (offset) *offset = addr - data.base;
1725 return true;
1726 }
1727 if (dladdr((void*)addr, &dlinfo) != 0) {
1728 if (dlinfo.dli_fname != NULL) {
1729 jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname);
1730 }
1731 if (dlinfo.dli_fbase != NULL && offset != NULL) {
1732 *offset = addr - (address)dlinfo.dli_fbase;
1733 }
1734 return true;
1735 }
1736
1737 buf[0] = '\0';
1738 if (offset) *offset = -1;
1739 return false;
1740 }
1741
1742 // Loads .dll/.so and
1743 // in case of error it checks if .dll/.so was built for the
1744 // same architecture as Hotspot is running on
1745
1746
1747 // Remember the stack's state. The Linux dynamic linker will change
1748 // the stack to 'executable' at most once, so we must safepoint only once.
1749 bool os::Linux::_stack_is_executable = false;
1750
1751 // VM operation that loads a library. This is necessary if stack protection
1752 // of the Java stacks can be lost during loading the library. If we
1753 // do not stop the Java threads, they can stack overflow before the stacks
1754 // are protected again.
1755 class VM_LinuxDllLoad: public VM_Operation {
1756 private:
1757 const char *_filename;
1758 char *_ebuf;
1759 int _ebuflen;
1760 void *_lib;
1761 public:
1762 VM_LinuxDllLoad(const char *fn, char *ebuf, int ebuflen) :
1763 _filename(fn), _ebuf(ebuf), _ebuflen(ebuflen), _lib(NULL) {}
1764 VMOp_Type type() const { return VMOp_LinuxDllLoad; }
1765 void doit() {
1766 _lib = os::Linux::dll_load_in_vmthread(_filename, _ebuf, _ebuflen);
1767 os::Linux::_stack_is_executable = true;
1768 }
1769 void* loaded_library() { return _lib; }
1770 };
1771
1772 void * os::dll_load(const char *filename, char *ebuf, int ebuflen) {
1773 void * result = NULL;
1774 bool load_attempted = false;
1775
1776 // Check whether the library to load might change execution rights
1777 // of the stack. If they are changed, the protection of the stack
1778 // guard pages will be lost. We need a safepoint to fix this.
1779 //
1780 // See Linux man page execstack(8) for more info.
1781 if (os::uses_stack_guard_pages() && !os::Linux::_stack_is_executable) {
1782 ElfFile ef(filename);
1783 if (!ef.specifies_noexecstack()) {
1784 if (!is_init_completed()) {
1785 os::Linux::_stack_is_executable = true;
1786 // This is OK - No Java threads have been created yet, and hence no
1787 // stack guard pages to fix.
1788 //
1789 // This should happen only when you are building JDK7 using a very
1790 // old version of JDK6 (e.g., with JPRT) and running test_gamma.
1791 //
1792 // Dynamic loader will make all stacks executable after
1793 // this function returns, and will not do that again.
1794 assert(Threads::first() == NULL, "no Java threads should exist yet.");
1795 } else {
1796 warning("You have loaded library %s which might have disabled stack guard. "
1797 "The VM will try to fix the stack guard now.\n"
1798 "It's highly recommended that you fix the library with "
1799 "'execstack -c <libfile>', or link it with '-z noexecstack'.",
1800 filename);
1801
1802 assert(Thread::current()->is_Java_thread(), "must be Java thread");
1803 JavaThread *jt = JavaThread::current();
1804 if (jt->thread_state() != _thread_in_native) {
1805 // This happens when a compiler thread tries to load a hsdis-<arch>.so file
1806 // that requires ExecStack. Cannot enter safe point. Let's give up.
1807 warning("Unable to fix stack guard. Giving up.");
1808 } else {
1809 if (!LoadExecStackDllInVMThread) {
1810 // This is for the case where the DLL has an static
1811 // constructor function that executes JNI code. We cannot
1812 // load such DLLs in the VMThread.
1813 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen);
1814 }
1815
1816 ThreadInVMfromNative tiv(jt);
1817 debug_only(VMNativeEntryWrapper vew;)
1818
1819 VM_LinuxDllLoad op(filename, ebuf, ebuflen);
1820 VMThread::execute(&op);
1821 if (LoadExecStackDllInVMThread) {
1822 result = op.loaded_library();
1823 }
1824 load_attempted = true;
1825 }
1826 }
1827 }
1828 }
1829
1830 if (!load_attempted) {
1831 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen);
1832 }
1833
1834 if (result != NULL) {
1835 // Successful loading
1836 return result;
1837 }
1838
1839 Elf32_Ehdr elf_head;
1840 int diag_msg_max_length=ebuflen-strlen(ebuf);
1841 char* diag_msg_buf=ebuf+strlen(ebuf);
1842
1843 if (diag_msg_max_length==0) {
1844 // No more space in ebuf for additional diagnostics message
1845 return NULL;
1846 }
1847
1848
1849 int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK);
1850
1851 if (file_descriptor < 0) {
1852 // Can't open library, report dlerror() message
1853 return NULL;
1854 }
1855
1856 bool failed_to_read_elf_head=
1857 (sizeof(elf_head)!=
1858 (::read(file_descriptor, &elf_head,sizeof(elf_head))));
1859
1860 ::close(file_descriptor);
1861 if (failed_to_read_elf_head) {
1862 // file i/o error - report dlerror() msg
1863 return NULL;
1864 }
1865
1866 typedef struct {
1867 Elf32_Half code; // Actual value as defined in elf.h
1868 Elf32_Half compat_class; // Compatibility of archs at VM's sense
1869 char elf_class; // 32 or 64 bit
1870 char endianess; // MSB or LSB
1871 char* name; // String representation
1872 } arch_t;
1873
1874 #ifndef EM_486
1875 #define EM_486 6 /* Intel 80486 */
1876 #endif
1877 #ifndef EM_AARCH64
1878 #define EM_AARCH64 183 /* ARM AARCH64 */
1879 #endif
1880
1881 static const arch_t arch_array[]={
1882 {EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
1883 {EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
1884 {EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"},
1885 {EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"},
1886 {EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
1887 {EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
1888 {EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"},
1889 {EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"},
1890 #if defined(VM_LITTLE_ENDIAN)
1891 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2LSB, (char*)"Power PC 64"},
1892 #else
1893 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"},
1894 #endif
1895 {EM_ARM, EM_ARM, ELFCLASS32, ELFDATA2LSB, (char*)"ARM"},
1896 {EM_S390, EM_S390, ELFCLASSNONE, ELFDATA2MSB, (char*)"IBM System/390"},
1897 {EM_ALPHA, EM_ALPHA, ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"},
1898 {EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"},
1899 {EM_MIPS, EM_MIPS, ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"},
1900 {EM_PARISC, EM_PARISC, ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"},
1901 {EM_68K, EM_68K, ELFCLASS32, ELFDATA2MSB, (char*)"M68k"},
1902 {EM_AARCH64, EM_AARCH64, ELFCLASS64, ELFDATA2LSB, (char*)"AARCH64"},
1903 };
1904
1905 #if (defined IA32)
1906 static Elf32_Half running_arch_code=EM_386;
1907 #elif (defined AMD64)
1908 static Elf32_Half running_arch_code=EM_X86_64;
1909 #elif (defined IA64)
1910 static Elf32_Half running_arch_code=EM_IA_64;
1911 #elif (defined __sparc) && (defined _LP64)
1912 static Elf32_Half running_arch_code=EM_SPARCV9;
1913 #elif (defined __sparc) && (!defined _LP64)
1914 static Elf32_Half running_arch_code=EM_SPARC;
1915 #elif (defined __powerpc64__)
1916 static Elf32_Half running_arch_code=EM_PPC64;
1917 #elif (defined __powerpc__)
1918 static Elf32_Half running_arch_code=EM_PPC;
1919 #elif (defined ARM)
1920 static Elf32_Half running_arch_code=EM_ARM;
1921 #elif (defined S390)
1922 static Elf32_Half running_arch_code=EM_S390;
1923 #elif (defined ALPHA)
1924 static Elf32_Half running_arch_code=EM_ALPHA;
1925 #elif (defined MIPSEL)
1926 static Elf32_Half running_arch_code=EM_MIPS_RS3_LE;
1927 #elif (defined PARISC)
1928 static Elf32_Half running_arch_code=EM_PARISC;
1929 #elif (defined MIPS)
1930 static Elf32_Half running_arch_code=EM_MIPS;
1931 #elif (defined M68K)
1932 static Elf32_Half running_arch_code=EM_68K;
1933 #elif (defined AARCH64)
1934 static Elf32_Half running_arch_code=EM_AARCH64;
1935 #else
1936 #error Method os::dll_load requires that one of following is defined:\
1937 IA32, AMD64, IA64, __sparc, __powerpc__, ARM, S390, ALPHA, MIPS, MIPSEL, PARISC, M68K, AARCH64
1938 #endif
1939
1940 // Identify compatability class for VM's architecture and library's architecture
1941 // Obtain string descriptions for architectures
1942
1943 arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL};
1944 int running_arch_index=-1;
1945
1946 for (unsigned int i=0; i < ARRAY_SIZE(arch_array); i++) {
1947 if (running_arch_code == arch_array[i].code) {
1948 running_arch_index = i;
1949 }
1950 if (lib_arch.code == arch_array[i].code) {
1951 lib_arch.compat_class = arch_array[i].compat_class;
1952 lib_arch.name = arch_array[i].name;
1953 }
1954 }
1955
1956 assert(running_arch_index != -1,
1957 "Didn't find running architecture code (running_arch_code) in arch_array");
1958 if (running_arch_index == -1) {
1959 // Even though running architecture detection failed
1960 // we may still continue with reporting dlerror() message
1961 return NULL;
1962 }
1963
1964 if (lib_arch.endianess != arch_array[running_arch_index].endianess) {
1965 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)");
1966 return NULL;
1967 }
1968
1969 #ifndef S390
1970 if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) {
1971 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)");
1972 return NULL;
1973 }
1974 #endif // !S390
1975
1976 if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) {
1977 if (lib_arch.name!=NULL) {
1978 ::snprintf(diag_msg_buf, diag_msg_max_length-1,
1979 " (Possible cause: can't load %s-bit .so on a %s-bit platform)",
1980 lib_arch.name, arch_array[running_arch_index].name);
1981 } else {
1982 ::snprintf(diag_msg_buf, diag_msg_max_length-1,
1983 " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)",
1984 lib_arch.code,
1985 arch_array[running_arch_index].name);
1986 }
1987 }
1988
1989 return NULL;
1990 }
1991
1992 void * os::Linux::dlopen_helper(const char *filename, char *ebuf,
1993 int ebuflen) {
1994 void * result = ::dlopen(filename, RTLD_LAZY);
1995 if (result == NULL) {
1996 ::strncpy(ebuf, ::dlerror(), ebuflen - 1);
1997 ebuf[ebuflen-1] = '\0';
1998 }
1999 return result;
2000 }
2001
2002 void * os::Linux::dll_load_in_vmthread(const char *filename, char *ebuf,
2003 int ebuflen) {
2004 void * result = NULL;
2005 if (LoadExecStackDllInVMThread) {
2006 result = dlopen_helper(filename, ebuf, ebuflen);
2007 }
2008
2009 // Since 7019808, libjvm.so is linked with -noexecstack. If the VM loads a
2010 // library that requires an executable stack, or which does not have this
2011 // stack attribute set, dlopen changes the stack attribute to executable. The
2012 // read protection of the guard pages gets lost.
2013 //
2014 // Need to check _stack_is_executable again as multiple VM_LinuxDllLoad
2015 // may have been queued at the same time.
2016
2017 if (!_stack_is_executable) {
2018 JavaThread *jt = Threads::first();
2019
2020 while (jt) {
2021 if (!jt->stack_guard_zone_unused() && // Stack not yet fully initialized
2022 jt->stack_yellow_zone_enabled()) { // No pending stack overflow exceptions
2023 if (!os::guard_memory((char *) jt->stack_red_zone_base() - jt->stack_red_zone_size(),
2024 jt->stack_yellow_zone_size() + jt->stack_red_zone_size())) {
2025 warning("Attempt to reguard stack yellow zone failed.");
2026 }
2027 }
2028 jt = jt->next();
2029 }
2030 }
2031
2032 return result;
2033 }
2034
2035 void* os::dll_lookup(void* handle, const char* name) {
2036 void* res = dlsym(handle, name);
2037 return res;
2038 }
2039
2040 void* os::get_default_process_handle() {
2041 return (void*)::dlopen(NULL, RTLD_LAZY);
2042 }
2043
2044 static bool _print_ascii_file(const char* filename, outputStream* st) {
2045 int fd = ::open(filename, O_RDONLY);
2046 if (fd == -1) {
2047 return false;
2048 }
2049
2050 char buf[32];
2051 int bytes;
2052 while ((bytes = ::read(fd, buf, sizeof(buf))) > 0) {
2053 st->print_raw(buf, bytes);
2054 }
2055
2056 ::close(fd);
2057
2058 return true;
2059 }
2060
2061 void os::print_dll_info(outputStream *st) {
2062 st->print_cr("Dynamic libraries:");
2063
2064 char fname[32];
2065 pid_t pid = os::Linux::gettid();
2066
2067 jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid);
2068
2069 if (!_print_ascii_file(fname, st)) {
2070 st->print("Can not get library information for pid = %d\n", pid);
2071 }
2072 }
2073
2074 int os::get_loaded_modules_info(os::LoadedModulesCallbackFunc callback, void *param) {
2075 FILE *procmapsFile = NULL;
2076
2077 // Open the procfs maps file for the current process
2078 if ((procmapsFile = fopen("/proc/self/maps", "r")) != NULL) {
2079 // Allocate PATH_MAX for file name plus a reasonable size for other fields.
2080 char line[PATH_MAX + 100];
2081
2082 // Read line by line from 'file'
2083 while (fgets(line, sizeof(line), procmapsFile) != NULL) {
2084 u8 base, top, offset, inode;
2085 char permissions[5];
2086 char device[6];
2087 char name[PATH_MAX + 1];
2088
2089 // Parse fields from line
2090 sscanf(line, "%lx-%lx %4s %lx %5s %ld %s", &base, &top, permissions, &offset, device, &inode, name);
2091
2092 // Filter by device id '00:00' so that we only get file system mapped files.
2093 if (strcmp(device, "00:00") != 0) {
2094
2095 // Call callback with the fields of interest
2096 if(callback(name, (address)base, (address)top, param)) {
2097 // Oops abort, callback aborted
2098 fclose(procmapsFile);
2099 return 1;
2100 }
2101 }
2102 }
2103 fclose(procmapsFile);
2104 }
2105 return 0;
2106 }
2107
2108 void os::print_os_info_brief(outputStream* st) {
2109 os::Linux::print_distro_info(st);
2110
2111 os::Posix::print_uname_info(st);
2112
2113 os::Linux::print_libversion_info(st);
2114
2115 }
2116
2117 void os::print_os_info(outputStream* st) {
2118 st->print("OS:");
2119
2120 os::Linux::print_distro_info(st);
2121
2122 os::Posix::print_uname_info(st);
2123
2124 // Print warning if unsafe chroot environment detected
2125 if (unsafe_chroot_detected) {
2126 st->print("WARNING!! ");
2127 st->print_cr("%s", unstable_chroot_error);
2128 }
2129
2130 os::Linux::print_libversion_info(st);
2131
2132 os::Posix::print_rlimit_info(st);
2133
2134 os::Posix::print_load_average(st);
2135
2136 os::Linux::print_full_memory_info(st);
2137 }
2138
2139 // Try to identify popular distros.
2140 // Most Linux distributions have a /etc/XXX-release file, which contains
2141 // the OS version string. Newer Linux distributions have a /etc/lsb-release
2142 // file that also contains the OS version string. Some have more than one
2143 // /etc/XXX-release file (e.g. Mandrake has both /etc/mandrake-release and
2144 // /etc/redhat-release.), so the order is important.
2145 // Any Linux that is based on Redhat (i.e. Oracle, Mandrake, Sun JDS...) have
2146 // their own specific XXX-release file as well as a redhat-release file.
2147 // Because of this the XXX-release file needs to be searched for before the
2148 // redhat-release file.
2149 // Since Red Hat has a lsb-release file that is not very descriptive the
2150 // search for redhat-release needs to be before lsb-release.
2151 // Since the lsb-release file is the new standard it needs to be searched
2152 // before the older style release files.
2153 // Searching system-release (Red Hat) and os-release (other Linuxes) are a
2154 // next to last resort. The os-release file is a new standard that contains
2155 // distribution information and the system-release file seems to be an old
2156 // standard that has been replaced by the lsb-release and os-release files.
2157 // Searching for the debian_version file is the last resort. It contains
2158 // an informative string like "6.0.6" or "wheezy/sid". Because of this
2159 // "Debian " is printed before the contents of the debian_version file.
2160 void os::Linux::print_distro_info(outputStream* st) {
2161 if (!_print_ascii_file("/etc/oracle-release", st) &&
2162 !_print_ascii_file("/etc/mandriva-release", st) &&
2163 !_print_ascii_file("/etc/mandrake-release", st) &&
2164 !_print_ascii_file("/etc/sun-release", st) &&
2165 !_print_ascii_file("/etc/redhat-release", st) &&
2166 !_print_ascii_file("/etc/lsb-release", st) &&
2167 !_print_ascii_file("/etc/SuSE-release", st) &&
2168 !_print_ascii_file("/etc/turbolinux-release", st) &&
2169 !_print_ascii_file("/etc/gentoo-release", st) &&
2170 !_print_ascii_file("/etc/ltib-release", st) &&
2171 !_print_ascii_file("/etc/angstrom-version", st) &&
2172 !_print_ascii_file("/etc/system-release", st) &&
2173 !_print_ascii_file("/etc/os-release", st)) {
2174
2175 if (file_exists("/etc/debian_version")) {
2176 st->print("Debian ");
2177 _print_ascii_file("/etc/debian_version", st);
2178 } else {
2179 st->print("Linux");
2180 }
2181 }
2182 st->cr();
2183 }
2184
2185 void os::Linux::print_libversion_info(outputStream* st) {
2186 // libc, pthread
2187 st->print("libc:");
2188 st->print("%s ", os::Linux::glibc_version());
2189 st->print("%s ", os::Linux::libpthread_version());
2190 if (os::Linux::is_LinuxThreads()) {
2191 st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed");
2192 }
2193 st->cr();
2194 }
2195
2196 void os::Linux::print_full_memory_info(outputStream* st) {
2197 st->print("\n/proc/meminfo:\n");
2198 _print_ascii_file("/proc/meminfo", st);
2199 st->cr();
2200 }
2201
2202 void os::print_memory_info(outputStream* st) {
2203
2204 st->print("Memory:");
2205 st->print(" %dk page", os::vm_page_size()>>10);
2206
2207 // values in struct sysinfo are "unsigned long"
2208 struct sysinfo si;
2209 sysinfo(&si);
2210
2211 st->print(", physical " UINT64_FORMAT "k",
2212 os::physical_memory() >> 10);
2213 st->print("(" UINT64_FORMAT "k free)",
2214 os::available_memory() >> 10);
2215 st->print(", swap " UINT64_FORMAT "k",
2216 ((jlong)si.totalswap * si.mem_unit) >> 10);
2217 st->print("(" UINT64_FORMAT "k free)",
2218 ((jlong)si.freeswap * si.mem_unit) >> 10);
2219 st->cr();
2220 }
2221
2222 void os::pd_print_cpu_info(outputStream* st) {
2223 st->print("\n/proc/cpuinfo:\n");
2224 if (!_print_ascii_file("/proc/cpuinfo", st)) {
2225 st->print(" <Not Available>");
2226 }
2227 st->cr();
2228 }
2229
2230 void os::print_siginfo(outputStream* st, void* siginfo) {
2231 const siginfo_t* si = (const siginfo_t*)siginfo;
2232
2233 os::Posix::print_siginfo_brief(st, si);
2234 #if INCLUDE_CDS
2235 if (si && (si->si_signo == SIGBUS || si->si_signo == SIGSEGV) &&
2236 UseSharedSpaces) {
2237 FileMapInfo* mapinfo = FileMapInfo::current_info();
2238 if (mapinfo->is_in_shared_space(si->si_addr)) {
2239 st->print("\n\nError accessing class data sharing archive." \
2240 " Mapped file inaccessible during execution, " \
2241 " possible disk/network problem.");
2242 }
2243 }
2244 #endif
2245 st->cr();
2246 }
2247
2248
2249 static void print_signal_handler(outputStream* st, int sig,
2250 char* buf, size_t buflen);
2251
2252 void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) {
2253 st->print_cr("Signal Handlers:");
2254 print_signal_handler(st, SIGSEGV, buf, buflen);
2255 print_signal_handler(st, SIGBUS , buf, buflen);
2256 print_signal_handler(st, SIGFPE , buf, buflen);
2257 print_signal_handler(st, SIGPIPE, buf, buflen);
2258 print_signal_handler(st, SIGXFSZ, buf, buflen);
2259 print_signal_handler(st, SIGILL , buf, buflen);
2260 print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen);
2261 print_signal_handler(st, SR_signum, buf, buflen);
2262 print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen);
2263 print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen);
2264 print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen);
2265 print_signal_handler(st, BREAK_SIGNAL, buf, buflen);
2266 #if defined(PPC64)
2267 print_signal_handler(st, SIGTRAP, buf, buflen);
2268 #endif
2269 }
2270
2271 static char saved_jvm_path[MAXPATHLEN] = {0};
2272
2273 // Find the full path to the current module, libjvm.so
2274 void os::jvm_path(char *buf, jint buflen) {
2275 // Error checking.
2276 if (buflen < MAXPATHLEN) {
2277 assert(false, "must use a large-enough buffer");
2278 buf[0] = '\0';
2279 return;
2280 }
2281 // Lazy resolve the path to current module.
2282 if (saved_jvm_path[0] != 0) {
2283 strcpy(buf, saved_jvm_path);
2284 return;
2285 }
2286
2287 char dli_fname[MAXPATHLEN];
2288 bool ret = dll_address_to_library_name(
2289 CAST_FROM_FN_PTR(address, os::jvm_path),
2290 dli_fname, sizeof(dli_fname), NULL);
2291 assert(ret, "cannot locate libjvm");
2292 char *rp = NULL;
2293 if (ret && dli_fname[0] != '\0') {
2294 rp = realpath(dli_fname, buf);
2295 }
2296 if (rp == NULL) {
2297 return;
2298 }
2299
2300 if (Arguments::sun_java_launcher_is_altjvm()) {
2301 // Support for the java launcher's '-XXaltjvm=<path>' option. Typical
2302 // value for buf is "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so".
2303 // If "/jre/lib/" appears at the right place in the string, then
2304 // assume we are installed in a JDK and we're done. Otherwise, check
2305 // for a JAVA_HOME environment variable and fix up the path so it
2306 // looks like libjvm.so is installed there (append a fake suffix
2307 // hotspot/libjvm.so).
2308 const char *p = buf + strlen(buf) - 1;
2309 for (int count = 0; p > buf && count < 5; ++count) {
2310 for (--p; p > buf && *p != '/'; --p)
2311 /* empty */ ;
2312 }
2313
2314 if (strncmp(p, "/jre/lib/", 9) != 0) {
2315 // Look for JAVA_HOME in the environment.
2316 char* java_home_var = ::getenv("JAVA_HOME");
2317 if (java_home_var != NULL && java_home_var[0] != 0) {
2318 char* jrelib_p;
2319 int len;
2320
2321 // Check the current module name "libjvm.so".
2322 p = strrchr(buf, '/');
2323 if (p == NULL) {
2324 return;
2325 }
2326 assert(strstr(p, "/libjvm") == p, "invalid library name");
2327
2328 rp = realpath(java_home_var, buf);
2329 if (rp == NULL) {
2330 return;
2331 }
2332
2333 // determine if this is a legacy image or modules image
2334 // modules image doesn't have "jre" subdirectory
2335 len = strlen(buf);
2336 assert(len < buflen, "Ran out of buffer room");
2337 jrelib_p = buf + len;
2338 snprintf(jrelib_p, buflen-len, "/jre/lib/%s", cpu_arch);
2339 if (0 != access(buf, F_OK)) {
2340 snprintf(jrelib_p, buflen-len, "/lib/%s", cpu_arch);
2341 }
2342
2343 if (0 == access(buf, F_OK)) {
2344 // Use current module name "libjvm.so"
2345 len = strlen(buf);
2346 snprintf(buf + len, buflen-len, "/hotspot/libjvm.so");
2347 } else {
2348 // Go back to path of .so
2349 rp = realpath(dli_fname, buf);
2350 if (rp == NULL) {
2351 return;
2352 }
2353 }
2354 }
2355 }
2356 }
2357
2358 strncpy(saved_jvm_path, buf, MAXPATHLEN);
2359 saved_jvm_path[MAXPATHLEN - 1] = '\0';
2360 }
2361
2362 void os::print_jni_name_prefix_on(outputStream* st, int args_size) {
2363 // no prefix required, not even "_"
2364 }
2365
2366 void os::print_jni_name_suffix_on(outputStream* st, int args_size) {
2367 // no suffix required
2368 }
2369
2370 ////////////////////////////////////////////////////////////////////////////////
2371 // sun.misc.Signal support
2372
2373 static volatile jint sigint_count = 0;
2374
2375 static void UserHandler(int sig, void *siginfo, void *context) {
2376 // 4511530 - sem_post is serialized and handled by the manager thread. When
2377 // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We
2378 // don't want to flood the manager thread with sem_post requests.
2379 if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1) {
2380 return;
2381 }
2382
2383 // Ctrl-C is pressed during error reporting, likely because the error
2384 // handler fails to abort. Let VM die immediately.
2385 if (sig == SIGINT && is_error_reported()) {
2386 os::die();
2387 }
2388
2389 os::signal_notify(sig);
2390 }
2391
2392 void* os::user_handler() {
2393 return CAST_FROM_FN_PTR(void*, UserHandler);
2394 }
2395
2396 class LinuxSemaphore : public os::PosixSemaphore {
2397 public:
2398 LinuxSemaphore(uint value = 0) : os::PosixSemaphore(value) {}
2399
2400 bool timedwait(unsigned int sec, int nsec) {
2401 struct timespec ts;
2402 // Semaphore's are always associated with CLOCK_REALTIME
2403 os::Linux::clock_gettime(CLOCK_REALTIME, &ts);
2404 // see unpackTime for discussion on overflow checking
2405 if (sec >= MAX_SECS) {
2406 ts.tv_sec += MAX_SECS;
2407 ts.tv_nsec = 0;
2408 } else {
2409 ts.tv_sec += sec;
2410 ts.tv_nsec += nsec;
2411 if (ts.tv_nsec >= NANOSECS_PER_SEC) {
2412 ts.tv_nsec -= NANOSECS_PER_SEC;
2413 ++ts.tv_sec; // note: this must be <= max_secs
2414 }
2415 }
2416
2417 return os::PosixSemaphore::timedwait(ts);
2418 }
2419 };
2420
2421 extern "C" {
2422 typedef void (*sa_handler_t)(int);
2423 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *);
2424 }
2425
2426 void* os::signal(int signal_number, void* handler) {
2427 struct sigaction sigAct, oldSigAct;
2428
2429 sigfillset(&(sigAct.sa_mask));
2430 sigAct.sa_flags = SA_RESTART|SA_SIGINFO;
2431 sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler);
2432
2433 if (sigaction(signal_number, &sigAct, &oldSigAct)) {
2434 // -1 means registration failed
2435 return (void *)-1;
2436 }
2437
2438 return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler);
2439 }
2440
2441 void os::signal_raise(int signal_number) {
2442 ::raise(signal_number);
2443 }
2444
2445 // The following code is moved from os.cpp for making this
2446 // code platform specific, which it is by its very nature.
2447
2448 // Will be modified when max signal is changed to be dynamic
2449 int os::sigexitnum_pd() {
2450 return NSIG;
2451 }
2452
2453 // a counter for each possible signal value
2454 static volatile jint pending_signals[NSIG+1] = { 0 };
2455
2456 // Linux(POSIX) specific hand shaking semaphore.
2457 static sem_t sig_sem;
2458 static LinuxSemaphore sr_semaphore;
2459
2460 void os::signal_init_pd() {
2461 // Initialize signal structures
2462 ::memset((void*)pending_signals, 0, sizeof(pending_signals));
2463
2464 // Initialize signal semaphore
2465 ::sem_init(&sig_sem, 0, 0);
2466 }
2467
2468 void os::signal_notify(int sig) {
2469 Atomic::inc(&pending_signals[sig]);
2470 ::sem_post(&sig_sem);
2471 }
2472
2473 static int check_pending_signals(bool wait) {
2474 Atomic::store(0, &sigint_count);
2475 for (;;) {
2476 for (int i = 0; i < NSIG + 1; i++) {
2477 jint n = pending_signals[i];
2478 if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) {
2479 return i;
2480 }
2481 }
2482 if (!wait) {
2483 return -1;
2484 }
2485 JavaThread *thread = JavaThread::current();
2486 ThreadBlockInVM tbivm(thread);
2487
2488 bool threadIsSuspended;
2489 do {
2490 thread->set_suspend_equivalent();
2491 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
2492 ::sem_wait(&sig_sem);
2493
2494 // were we externally suspended while we were waiting?
2495 threadIsSuspended = thread->handle_special_suspend_equivalent_condition();
2496 if (threadIsSuspended) {
2497 // The semaphore has been incremented, but while we were waiting
2498 // another thread suspended us. We don't want to continue running
2499 // while suspended because that would surprise the thread that
2500 // suspended us.
2501 ::sem_post(&sig_sem);
2502
2503 thread->java_suspend_self();
2504 }
2505 } while (threadIsSuspended);
2506 }
2507 }
2508
2509 int os::signal_lookup() {
2510 return check_pending_signals(false);
2511 }
2512
2513 int os::signal_wait() {
2514 return check_pending_signals(true);
2515 }
2516
2517 ////////////////////////////////////////////////////////////////////////////////
2518 // Virtual Memory
2519
2520 int os::vm_page_size() {
2521 // Seems redundant as all get out
2522 assert(os::Linux::page_size() != -1, "must call os::init");
2523 return os::Linux::page_size();
2524 }
2525
2526 // Solaris allocates memory by pages.
2527 int os::vm_allocation_granularity() {
2528 assert(os::Linux::page_size() != -1, "must call os::init");
2529 return os::Linux::page_size();
2530 }
2531
2532 // Rationale behind this function:
2533 // current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable
2534 // mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get
2535 // samples for JITted code. Here we create private executable mapping over the code cache
2536 // and then we can use standard (well, almost, as mapping can change) way to provide
2537 // info for the reporting script by storing timestamp and location of symbol
2538 void linux_wrap_code(char* base, size_t size) {
2539 static volatile jint cnt = 0;
2540
2541 if (!UseOprofile) {
2542 return;
2543 }
2544
2545 char buf[PATH_MAX+1];
2546 int num = Atomic::add(1, &cnt);
2547
2548 snprintf(buf, sizeof(buf), "%s/hs-vm-%d-%d",
2549 os::get_temp_directory(), os::current_process_id(), num);
2550 unlink(buf);
2551
2552 int fd = ::open(buf, O_CREAT | O_RDWR, S_IRWXU);
2553
2554 if (fd != -1) {
2555 off_t rv = ::lseek(fd, size-2, SEEK_SET);
2556 if (rv != (off_t)-1) {
2557 if (::write(fd, "", 1) == 1) {
2558 mmap(base, size,
2559 PROT_READ|PROT_WRITE|PROT_EXEC,
2560 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0);
2561 }
2562 }
2563 ::close(fd);
2564 unlink(buf);
2565 }
2566 }
2567
2568 static bool recoverable_mmap_error(int err) {
2569 // See if the error is one we can let the caller handle. This
2570 // list of errno values comes from JBS-6843484. I can't find a
2571 // Linux man page that documents this specific set of errno
2572 // values so while this list currently matches Solaris, it may
2573 // change as we gain experience with this failure mode.
2574 switch (err) {
2575 case EBADF:
2576 case EINVAL:
2577 case ENOTSUP:
2578 // let the caller deal with these errors
2579 return true;
2580
2581 default:
2582 // Any remaining errors on this OS can cause our reserved mapping
2583 // to be lost. That can cause confusion where different data
2584 // structures think they have the same memory mapped. The worst
2585 // scenario is if both the VM and a library think they have the
2586 // same memory mapped.
2587 return false;
2588 }
2589 }
2590
2591 static void warn_fail_commit_memory(char* addr, size_t size, bool exec,
2592 int err) {
2593 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT
2594 ", %d) failed; error='%s' (errno=%d)", addr, size, exec,
2595 strerror(err), err);
2596 }
2597
2598 static void warn_fail_commit_memory(char* addr, size_t size,
2599 size_t alignment_hint, bool exec,
2600 int err) {
2601 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT
2602 ", " SIZE_FORMAT ", %d) failed; error='%s' (errno=%d)", addr, size,
2603 alignment_hint, exec, strerror(err), err);
2604 }
2605
2606 // NOTE: Linux kernel does not really reserve the pages for us.
2607 // All it does is to check if there are enough free pages
2608 // left at the time of mmap(). This could be a potential
2609 // problem.
2610 int os::Linux::commit_memory_impl(char* addr, size_t size, bool exec) {
2611 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
2612 uintptr_t res = (uintptr_t) ::mmap(addr, size, prot,
2613 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0);
2614 if (res != (uintptr_t) MAP_FAILED) {
2615 if (UseNUMAInterleaving) {
2616 numa_make_global(addr, size);
2617 }
2618 return 0;
2619 }
2620
2621 int err = errno; // save errno from mmap() call above
2622
2623 if (!recoverable_mmap_error(err)) {
2624 warn_fail_commit_memory(addr, size, exec, err);
2625 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, "committing reserved memory.");
2626 }
2627
2628 return err;
2629 }
2630
2631 bool os::pd_commit_memory(char* addr, size_t size, bool exec) {
2632 return os::Linux::commit_memory_impl(addr, size, exec) == 0;
2633 }
2634
2635 void os::pd_commit_memory_or_exit(char* addr, size_t size, bool exec,
2636 const char* mesg) {
2637 assert(mesg != NULL, "mesg must be specified");
2638 int err = os::Linux::commit_memory_impl(addr, size, exec);
2639 if (err != 0) {
2640 // the caller wants all commit errors to exit with the specified mesg:
2641 warn_fail_commit_memory(addr, size, exec, err);
2642 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg);
2643 }
2644 }
2645
2646 // Define MAP_HUGETLB here so we can build HotSpot on old systems.
2647 #ifndef MAP_HUGETLB
2648 #define MAP_HUGETLB 0x40000
2649 #endif
2650
2651 // Define MADV_HUGEPAGE here so we can build HotSpot on old systems.
2652 #ifndef MADV_HUGEPAGE
2653 #define MADV_HUGEPAGE 14
2654 #endif
2655
2656 int os::Linux::commit_memory_impl(char* addr, size_t size,
2657 size_t alignment_hint, bool exec) {
2658 int err = os::Linux::commit_memory_impl(addr, size, exec);
2659 if (err == 0) {
2660 realign_memory(addr, size, alignment_hint);
2661 }
2662 return err;
2663 }
2664
2665 bool os::pd_commit_memory(char* addr, size_t size, size_t alignment_hint,
2666 bool exec) {
2667 return os::Linux::commit_memory_impl(addr, size, alignment_hint, exec) == 0;
2668 }
2669
2670 void os::pd_commit_memory_or_exit(char* addr, size_t size,
2671 size_t alignment_hint, bool exec,
2672 const char* mesg) {
2673 assert(mesg != NULL, "mesg must be specified");
2674 int err = os::Linux::commit_memory_impl(addr, size, alignment_hint, exec);
2675 if (err != 0) {
2676 // the caller wants all commit errors to exit with the specified mesg:
2677 warn_fail_commit_memory(addr, size, alignment_hint, exec, err);
2678 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg);
2679 }
2680 }
2681
2682 void os::pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint) {
2683 if (UseTransparentHugePages && alignment_hint > (size_t)vm_page_size()) {
2684 // We don't check the return value: madvise(MADV_HUGEPAGE) may not
2685 // be supported or the memory may already be backed by huge pages.
2686 ::madvise(addr, bytes, MADV_HUGEPAGE);
2687 }
2688 }
2689
2690 void os::pd_free_memory(char *addr, size_t bytes, size_t alignment_hint) {
2691 // This method works by doing an mmap over an existing mmaping and effectively discarding
2692 // the existing pages. However it won't work for SHM-based large pages that cannot be
2693 // uncommitted at all. We don't do anything in this case to avoid creating a segment with
2694 // small pages on top of the SHM segment. This method always works for small pages, so we
2695 // allow that in any case.
2696 if (alignment_hint <= (size_t)os::vm_page_size() || can_commit_large_page_memory()) {
2697 commit_memory(addr, bytes, alignment_hint, !ExecMem);
2698 }
2699 }
2700
2701 void os::numa_make_global(char *addr, size_t bytes) {
2702 Linux::numa_interleave_memory(addr, bytes);
2703 }
2704
2705 // Define for numa_set_bind_policy(int). Setting the argument to 0 will set the
2706 // bind policy to MPOL_PREFERRED for the current thread.
2707 #define USE_MPOL_PREFERRED 0
2708
2709 void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) {
2710 // To make NUMA and large pages more robust when both enabled, we need to ease
2711 // the requirements on where the memory should be allocated. MPOL_BIND is the
2712 // default policy and it will force memory to be allocated on the specified
2713 // node. Changing this to MPOL_PREFERRED will prefer to allocate the memory on
2714 // the specified node, but will not force it. Using this policy will prevent
2715 // getting SIGBUS when trying to allocate large pages on NUMA nodes with no
2716 // free large pages.
2717 Linux::numa_set_bind_policy(USE_MPOL_PREFERRED);
2718 Linux::numa_tonode_memory(addr, bytes, lgrp_hint);
2719 }
2720
2721 bool os::numa_topology_changed() { return false; }
2722
2723 size_t os::numa_get_groups_num() {
2724 int max_node = Linux::numa_max_node();
2725 return max_node > 0 ? max_node + 1 : 1;
2726 }
2727
2728 int os::numa_get_group_id() {
2729 int cpu_id = Linux::sched_getcpu();
2730 if (cpu_id != -1) {
2731 int lgrp_id = Linux::get_node_by_cpu(cpu_id);
2732 if (lgrp_id != -1) {
2733 return lgrp_id;
2734 }
2735 }
2736 return 0;
2737 }
2738
2739 size_t os::numa_get_leaf_groups(int *ids, size_t size) {
2740 for (size_t i = 0; i < size; i++) {
2741 ids[i] = i;
2742 }
2743 return size;
2744 }
2745
2746 bool os::get_page_info(char *start, page_info* info) {
2747 return false;
2748 }
2749
2750 char *os::scan_pages(char *start, char* end, page_info* page_expected,
2751 page_info* page_found) {
2752 return end;
2753 }
2754
2755
2756 int os::Linux::sched_getcpu_syscall(void) {
2757 unsigned int cpu;
2758 int retval = -1;
2759
2760 #if defined(IA32)
2761 #ifndef SYS_getcpu
2762 #define SYS_getcpu 318
2763 #endif
2764 retval = syscall(SYS_getcpu, &cpu, NULL, NULL);
2765 #elif defined(AMD64)
2766 // Unfortunately we have to bring all these macros here from vsyscall.h
2767 // to be able to compile on old linuxes.
2768 #define __NR_vgetcpu 2
2769 #define VSYSCALL_START (-10UL << 20)
2770 #define VSYSCALL_SIZE 1024
2771 #define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr))
2772 typedef long (*vgetcpu_t)(unsigned int *cpu, unsigned int *node, unsigned long *tcache);
2773 vgetcpu_t vgetcpu = (vgetcpu_t)VSYSCALL_ADDR(__NR_vgetcpu);
2774 retval = vgetcpu(&cpu, NULL, NULL);
2775 #endif
2776
2777 return (retval == -1) ? retval : cpu;
2778 }
2779
2780 // Something to do with the numa-aware allocator needs these symbols
2781 extern "C" JNIEXPORT void numa_warn(int number, char *where, ...) { }
2782 extern "C" JNIEXPORT void numa_error(char *where) { }
2783 extern "C" JNIEXPORT int fork1() { return fork(); }
2784
2785
2786 // If we are running with libnuma version > 2, then we should
2787 // be trying to use symbols with versions 1.1
2788 // If we are running with earlier version, which did not have symbol versions,
2789 // we should use the base version.
2790 void* os::Linux::libnuma_dlsym(void* handle, const char *name) {
2791 void *f = dlvsym(handle, name, "libnuma_1.1");
2792 if (f == NULL) {
2793 f = dlsym(handle, name);
2794 }
2795 return f;
2796 }
2797
2798 bool os::Linux::libnuma_init() {
2799 // sched_getcpu() should be in libc.
2800 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t,
2801 dlsym(RTLD_DEFAULT, "sched_getcpu")));
2802
2803 // If it's not, try a direct syscall.
2804 if (sched_getcpu() == -1) {
2805 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t,
2806 (void*)&sched_getcpu_syscall));
2807 }
2808
2809 if (sched_getcpu() != -1) { // Does it work?
2810 void *handle = dlopen("libnuma.so.1", RTLD_LAZY);
2811 if (handle != NULL) {
2812 set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t,
2813 libnuma_dlsym(handle, "numa_node_to_cpus")));
2814 set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t,
2815 libnuma_dlsym(handle, "numa_max_node")));
2816 set_numa_available(CAST_TO_FN_PTR(numa_available_func_t,
2817 libnuma_dlsym(handle, "numa_available")));
2818 set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t,
2819 libnuma_dlsym(handle, "numa_tonode_memory")));
2820 set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t,
2821 libnuma_dlsym(handle, "numa_interleave_memory")));
2822 set_numa_set_bind_policy(CAST_TO_FN_PTR(numa_set_bind_policy_func_t,
2823 libnuma_dlsym(handle, "numa_set_bind_policy")));
2824
2825
2826 if (numa_available() != -1) {
2827 set_numa_all_nodes((unsigned long*)libnuma_dlsym(handle, "numa_all_nodes"));
2828 // Create a cpu -> node mapping
2829 _cpu_to_node = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<int>(0, true);
2830 rebuild_cpu_to_node_map();
2831 return true;
2832 }
2833 }
2834 }
2835 return false;
2836 }
2837
2838 // rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id.
2839 // The table is later used in get_node_by_cpu().
2840 void os::Linux::rebuild_cpu_to_node_map() {
2841 const size_t NCPUS = 32768; // Since the buffer size computation is very obscure
2842 // in libnuma (possible values are starting from 16,
2843 // and continuing up with every other power of 2, but less
2844 // than the maximum number of CPUs supported by kernel), and
2845 // is a subject to change (in libnuma version 2 the requirements
2846 // are more reasonable) we'll just hardcode the number they use
2847 // in the library.
2848 const size_t BitsPerCLong = sizeof(long) * CHAR_BIT;
2849
2850 size_t cpu_num = os::active_processor_count();
2851 size_t cpu_map_size = NCPUS / BitsPerCLong;
2852 size_t cpu_map_valid_size =
2853 MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size);
2854
2855 cpu_to_node()->clear();
2856 cpu_to_node()->at_grow(cpu_num - 1);
2857 size_t node_num = numa_get_groups_num();
2858
2859 unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size, mtInternal);
2860 for (size_t i = 0; i < node_num; i++) {
2861 if (numa_node_to_cpus(i, cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) {
2862 for (size_t j = 0; j < cpu_map_valid_size; j++) {
2863 if (cpu_map[j] != 0) {
2864 for (size_t k = 0; k < BitsPerCLong; k++) {
2865 if (cpu_map[j] & (1UL << k)) {
2866 cpu_to_node()->at_put(j * BitsPerCLong + k, i);
2867 }
2868 }
2869 }
2870 }
2871 }
2872 }
2873 FREE_C_HEAP_ARRAY(unsigned long, cpu_map);
2874 }
2875
2876 int os::Linux::get_node_by_cpu(int cpu_id) {
2877 if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) {
2878 return cpu_to_node()->at(cpu_id);
2879 }
2880 return -1;
2881 }
2882
2883 GrowableArray<int>* os::Linux::_cpu_to_node;
2884 os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu;
2885 os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus;
2886 os::Linux::numa_max_node_func_t os::Linux::_numa_max_node;
2887 os::Linux::numa_available_func_t os::Linux::_numa_available;
2888 os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory;
2889 os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory;
2890 os::Linux::numa_set_bind_policy_func_t os::Linux::_numa_set_bind_policy;
2891 unsigned long* os::Linux::_numa_all_nodes;
2892
2893 bool os::pd_uncommit_memory(char* addr, size_t size) {
2894 uintptr_t res = (uintptr_t) ::mmap(addr, size, PROT_NONE,
2895 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0);
2896 return res != (uintptr_t) MAP_FAILED;
2897 }
2898
2899 static address get_stack_commited_bottom(address bottom, size_t size) {
2900 address nbot = bottom;
2901 address ntop = bottom + size;
2902
2903 size_t page_sz = os::vm_page_size();
2904 unsigned pages = size / page_sz;
2905
2906 unsigned char vec[1];
2907 unsigned imin = 1, imax = pages + 1, imid;
2908 int mincore_return_value = 0;
2909
2910 assert(imin <= imax, "Unexpected page size");
2911
2912 while (imin < imax) {
2913 imid = (imax + imin) / 2;
2914 nbot = ntop - (imid * page_sz);
2915
2916 // Use a trick with mincore to check whether the page is mapped or not.
2917 // mincore sets vec to 1 if page resides in memory and to 0 if page
2918 // is swapped output but if page we are asking for is unmapped
2919 // it returns -1,ENOMEM
2920 mincore_return_value = mincore(nbot, page_sz, vec);
2921
2922 if (mincore_return_value == -1) {
2923 // Page is not mapped go up
2924 // to find first mapped page
2925 if (errno != EAGAIN) {
2926 assert(errno == ENOMEM, "Unexpected mincore errno");
2927 imax = imid;
2928 }
2929 } else {
2930 // Page is mapped go down
2931 // to find first not mapped page
2932 imin = imid + 1;
2933 }
2934 }
2935
2936 nbot = nbot + page_sz;
2937
2938 // Adjust stack bottom one page up if last checked page is not mapped
2939 if (mincore_return_value == -1) {
2940 nbot = nbot + page_sz;
2941 }
2942
2943 return nbot;
2944 }
2945
2946
2947 // Linux uses a growable mapping for the stack, and if the mapping for
2948 // the stack guard pages is not removed when we detach a thread the
2949 // stack cannot grow beyond the pages where the stack guard was
2950 // mapped. If at some point later in the process the stack expands to
2951 // that point, the Linux kernel cannot expand the stack any further
2952 // because the guard pages are in the way, and a segfault occurs.
2953 //
2954 // However, it's essential not to split the stack region by unmapping
2955 // a region (leaving a hole) that's already part of the stack mapping,
2956 // so if the stack mapping has already grown beyond the guard pages at
2957 // the time we create them, we have to truncate the stack mapping.
2958 // So, we need to know the extent of the stack mapping when
2959 // create_stack_guard_pages() is called.
2960
2961 // We only need this for stacks that are growable: at the time of
2962 // writing thread stacks don't use growable mappings (i.e. those
2963 // creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this
2964 // only applies to the main thread.
2965
2966 // If the (growable) stack mapping already extends beyond the point
2967 // where we're going to put our guard pages, truncate the mapping at
2968 // that point by munmap()ping it. This ensures that when we later
2969 // munmap() the guard pages we don't leave a hole in the stack
2970 // mapping. This only affects the main/initial thread
2971
2972 bool os::pd_create_stack_guard_pages(char* addr, size_t size) {
2973 if (os::Linux::is_initial_thread()) {
2974 // As we manually grow stack up to bottom inside create_attached_thread(),
2975 // it's likely that os::Linux::initial_thread_stack_bottom is mapped and
2976 // we don't need to do anything special.
2977 // Check it first, before calling heavy function.
2978 uintptr_t stack_extent = (uintptr_t) os::Linux::initial_thread_stack_bottom();
2979 unsigned char vec[1];
2980
2981 if (mincore((address)stack_extent, os::vm_page_size(), vec) == -1) {
2982 // Fallback to slow path on all errors, including EAGAIN
2983 stack_extent = (uintptr_t) get_stack_commited_bottom(
2984 os::Linux::initial_thread_stack_bottom(),
2985 (size_t)addr - stack_extent);
2986 }
2987
2988 if (stack_extent < (uintptr_t)addr) {
2989 ::munmap((void*)stack_extent, (uintptr_t)(addr - stack_extent));
2990 }
2991 }
2992
2993 return os::commit_memory(addr, size, !ExecMem);
2994 }
2995
2996 // If this is a growable mapping, remove the guard pages entirely by
2997 // munmap()ping them. If not, just call uncommit_memory(). This only
2998 // affects the main/initial thread, but guard against future OS changes
2999 // It's safe to always unmap guard pages for initial thread because we
3000 // always place it right after end of the mapped region
3001
3002 bool os::remove_stack_guard_pages(char* addr, size_t size) {
3003 uintptr_t stack_extent, stack_base;
3004
3005 if (os::Linux::is_initial_thread()) {
3006 return ::munmap(addr, size) == 0;
3007 }
3008
3009 return os::uncommit_memory(addr, size);
3010 }
3011
3012 static address _highest_vm_reserved_address = NULL;
3013
3014 // If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory
3015 // at 'requested_addr'. If there are existing memory mappings at the same
3016 // location, however, they will be overwritten. If 'fixed' is false,
3017 // 'requested_addr' is only treated as a hint, the return value may or
3018 // may not start from the requested address. Unlike Linux mmap(), this
3019 // function returns NULL to indicate failure.
3020 static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) {
3021 char * addr;
3022 int flags;
3023
3024 flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS;
3025 if (fixed) {
3026 assert((uintptr_t)requested_addr % os::Linux::page_size() == 0, "unaligned address");
3027 flags |= MAP_FIXED;
3028 }
3029
3030 // Map reserved/uncommitted pages PROT_NONE so we fail early if we
3031 // touch an uncommitted page. Otherwise, the read/write might
3032 // succeed if we have enough swap space to back the physical page.
3033 addr = (char*)::mmap(requested_addr, bytes, PROT_NONE,
3034 flags, -1, 0);
3035
3036 if (addr != MAP_FAILED) {
3037 // anon_mmap() should only get called during VM initialization,
3038 // don't need lock (actually we can skip locking even it can be called
3039 // from multiple threads, because _highest_vm_reserved_address is just a
3040 // hint about the upper limit of non-stack memory regions.)
3041 if ((address)addr + bytes > _highest_vm_reserved_address) {
3042 _highest_vm_reserved_address = (address)addr + bytes;
3043 }
3044 }
3045
3046 return addr == MAP_FAILED ? NULL : addr;
3047 }
3048
3049 // Don't update _highest_vm_reserved_address, because there might be memory
3050 // regions above addr + size. If so, releasing a memory region only creates
3051 // a hole in the address space, it doesn't help prevent heap-stack collision.
3052 //
3053 static int anon_munmap(char * addr, size_t size) {
3054 return ::munmap(addr, size) == 0;
3055 }
3056
3057 char* os::pd_reserve_memory(size_t bytes, char* requested_addr,
3058 size_t alignment_hint) {
3059 return anon_mmap(requested_addr, bytes, (requested_addr != NULL));
3060 }
3061
3062 bool os::pd_release_memory(char* addr, size_t size) {
3063 return anon_munmap(addr, size);
3064 }
3065
3066 static address highest_vm_reserved_address() {
3067 return _highest_vm_reserved_address;
3068 }
3069
3070 static bool linux_mprotect(char* addr, size_t size, int prot) {
3071 // Linux wants the mprotect address argument to be page aligned.
3072 char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::page_size());
3073
3074 // According to SUSv3, mprotect() should only be used with mappings
3075 // established by mmap(), and mmap() always maps whole pages. Unaligned
3076 // 'addr' likely indicates problem in the VM (e.g. trying to change
3077 // protection of malloc'ed or statically allocated memory). Check the
3078 // caller if you hit this assert.
3079 assert(addr == bottom, "sanity check");
3080
3081 size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Linux::page_size());
3082 return ::mprotect(bottom, size, prot) == 0;
3083 }
3084
3085 // Set protections specified
3086 bool os::protect_memory(char* addr, size_t bytes, ProtType prot,
3087 bool is_committed) {
3088 unsigned int p = 0;
3089 switch (prot) {
3090 case MEM_PROT_NONE: p = PROT_NONE; break;
3091 case MEM_PROT_READ: p = PROT_READ; break;
3092 case MEM_PROT_RW: p = PROT_READ|PROT_WRITE; break;
3093 case MEM_PROT_RWX: p = PROT_READ|PROT_WRITE|PROT_EXEC; break;
3094 default:
3095 ShouldNotReachHere();
3096 }
3097 // is_committed is unused.
3098 return linux_mprotect(addr, bytes, p);
3099 }
3100
3101 bool os::guard_memory(char* addr, size_t size) {
3102 return linux_mprotect(addr, size, PROT_NONE);
3103 }
3104
3105 bool os::unguard_memory(char* addr, size_t size) {
3106 return linux_mprotect(addr, size, PROT_READ|PROT_WRITE);
3107 }
3108
3109 bool os::Linux::transparent_huge_pages_sanity_check(bool warn,
3110 size_t page_size) {
3111 bool result = false;
3112 void *p = mmap(NULL, page_size * 2, PROT_READ|PROT_WRITE,
3113 MAP_ANONYMOUS|MAP_PRIVATE,
3114 -1, 0);
3115 if (p != MAP_FAILED) {
3116 void *aligned_p = align_ptr_up(p, page_size);
3117
3118 result = madvise(aligned_p, page_size, MADV_HUGEPAGE) == 0;
3119
3120 munmap(p, page_size * 2);
3121 }
3122
3123 if (warn && !result) {
3124 warning("TransparentHugePages is not supported by the operating system.");
3125 }
3126
3127 return result;
3128 }
3129
3130 bool os::Linux::hugetlbfs_sanity_check(bool warn, size_t page_size) {
3131 bool result = false;
3132 void *p = mmap(NULL, page_size, PROT_READ|PROT_WRITE,
3133 MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB,
3134 -1, 0);
3135
3136 if (p != MAP_FAILED) {
3137 // We don't know if this really is a huge page or not.
3138 FILE *fp = fopen("/proc/self/maps", "r");
3139 if (fp) {
3140 while (!feof(fp)) {
3141 char chars[257];
3142 long x = 0;
3143 if (fgets(chars, sizeof(chars), fp)) {
3144 if (sscanf(chars, "%lx-%*x", &x) == 1
3145 && x == (long)p) {
3146 if (strstr (chars, "hugepage")) {
3147 result = true;
3148 break;
3149 }
3150 }
3151 }
3152 }
3153 fclose(fp);
3154 }
3155 munmap(p, page_size);
3156 }
3157
3158 if (warn && !result) {
3159 warning("HugeTLBFS is not supported by the operating system.");
3160 }
3161
3162 return result;
3163 }
3164
3165 // Set the coredump_filter bits to include largepages in core dump (bit 6)
3166 //
3167 // From the coredump_filter documentation:
3168 //
3169 // - (bit 0) anonymous private memory
3170 // - (bit 1) anonymous shared memory
3171 // - (bit 2) file-backed private memory
3172 // - (bit 3) file-backed shared memory
3173 // - (bit 4) ELF header pages in file-backed private memory areas (it is
3174 // effective only if the bit 2 is cleared)
3175 // - (bit 5) hugetlb private memory
3176 // - (bit 6) hugetlb shared memory
3177 //
3178 static void set_coredump_filter(void) {
3179 FILE *f;
3180 long cdm;
3181
3182 if ((f = fopen("/proc/self/coredump_filter", "r+")) == NULL) {
3183 return;
3184 }
3185
3186 if (fscanf(f, "%lx", &cdm) != 1) {
3187 fclose(f);
3188 return;
3189 }
3190
3191 rewind(f);
3192
3193 if ((cdm & LARGEPAGES_BIT) == 0) {
3194 cdm |= LARGEPAGES_BIT;
3195 fprintf(f, "%#lx", cdm);
3196 }
3197
3198 fclose(f);
3199 }
3200
3201 // Large page support
3202
3203 static size_t _large_page_size = 0;
3204
3205 size_t os::Linux::find_large_page_size() {
3206 size_t large_page_size = 0;
3207
3208 // large_page_size on Linux is used to round up heap size. x86 uses either
3209 // 2M or 4M page, depending on whether PAE (Physical Address Extensions)
3210 // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use
3211 // page as large as 256M.
3212 //
3213 // Here we try to figure out page size by parsing /proc/meminfo and looking
3214 // for a line with the following format:
3215 // Hugepagesize: 2048 kB
3216 //
3217 // If we can't determine the value (e.g. /proc is not mounted, or the text
3218 // format has been changed), we'll use the largest page size supported by
3219 // the processor.
3220
3221 #ifndef ZERO
3222 large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M)
3223 ARM32_ONLY(2 * M) PPC_ONLY(4 * M) AARCH64_ONLY(2 * M);
3224 #endif // ZERO
3225
3226 FILE *fp = fopen("/proc/meminfo", "r");
3227 if (fp) {
3228 while (!feof(fp)) {
3229 int x = 0;
3230 char buf[16];
3231 if (fscanf(fp, "Hugepagesize: %d", &x) == 1) {
3232 if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) {
3233 large_page_size = x * K;
3234 break;
3235 }
3236 } else {
3237 // skip to next line
3238 for (;;) {
3239 int ch = fgetc(fp);
3240 if (ch == EOF || ch == (int)'\n') break;
3241 }
3242 }
3243 }
3244 fclose(fp);
3245 }
3246
3247 if (!FLAG_IS_DEFAULT(LargePageSizeInBytes) && LargePageSizeInBytes != large_page_size) {
3248 warning("Setting LargePageSizeInBytes has no effect on this OS. Large page size is "
3249 SIZE_FORMAT "%s.", byte_size_in_proper_unit(large_page_size),
3250 proper_unit_for_byte_size(large_page_size));
3251 }
3252
3253 return large_page_size;
3254 }
3255
3256 size_t os::Linux::setup_large_page_size() {
3257 _large_page_size = Linux::find_large_page_size();
3258 const size_t default_page_size = (size_t)Linux::page_size();
3259 if (_large_page_size > default_page_size) {
3260 _page_sizes[0] = _large_page_size;
3261 _page_sizes[1] = default_page_size;
3262 _page_sizes[2] = 0;
3263 }
3264
3265 return _large_page_size;
3266 }
3267
3268 bool os::Linux::setup_large_page_type(size_t page_size) {
3269 if (FLAG_IS_DEFAULT(UseHugeTLBFS) &&
3270 FLAG_IS_DEFAULT(UseSHM) &&
3271 FLAG_IS_DEFAULT(UseTransparentHugePages)) {
3272
3273 // The type of large pages has not been specified by the user.
3274
3275 // Try UseHugeTLBFS and then UseSHM.
3276 UseHugeTLBFS = UseSHM = true;
3277
3278 // Don't try UseTransparentHugePages since there are known
3279 // performance issues with it turned on. This might change in the future.
3280 UseTransparentHugePages = false;
3281 }
3282
3283 if (UseTransparentHugePages) {
3284 bool warn_on_failure = !FLAG_IS_DEFAULT(UseTransparentHugePages);
3285 if (transparent_huge_pages_sanity_check(warn_on_failure, page_size)) {
3286 UseHugeTLBFS = false;
3287 UseSHM = false;
3288 return true;
3289 }
3290 UseTransparentHugePages = false;
3291 }
3292
3293 if (UseHugeTLBFS) {
3294 bool warn_on_failure = !FLAG_IS_DEFAULT(UseHugeTLBFS);
3295 if (hugetlbfs_sanity_check(warn_on_failure, page_size)) {
3296 UseSHM = false;
3297 return true;
3298 }
3299 UseHugeTLBFS = false;
3300 }
3301
3302 return UseSHM;
3303 }
3304
3305 void os::large_page_init() {
3306 if (!UseLargePages &&
3307 !UseTransparentHugePages &&
3308 !UseHugeTLBFS &&
3309 !UseSHM) {
3310 // Not using large pages.
3311 return;
3312 }
3313
3314 if (!FLAG_IS_DEFAULT(UseLargePages) && !UseLargePages) {
3315 // The user explicitly turned off large pages.
3316 // Ignore the rest of the large pages flags.
3317 UseTransparentHugePages = false;
3318 UseHugeTLBFS = false;
3319 UseSHM = false;
3320 return;
3321 }
3322
3323 size_t large_page_size = Linux::setup_large_page_size();
3324 UseLargePages = Linux::setup_large_page_type(large_page_size);
3325
3326 set_coredump_filter();
3327 }
3328
3329 #ifndef SHM_HUGETLB
3330 #define SHM_HUGETLB 04000
3331 #endif
3332
3333 char* os::Linux::reserve_memory_special_shm(size_t bytes, size_t alignment,
3334 char* req_addr, bool exec) {
3335 // "exec" is passed in but not used. Creating the shared image for
3336 // the code cache doesn't have an SHM_X executable permission to check.
3337 assert(UseLargePages && UseSHM, "only for SHM large pages");
3338 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address");
3339
3340 if (!is_size_aligned(bytes, os::large_page_size()) || alignment > os::large_page_size()) {
3341 return NULL; // Fallback to small pages.
3342 }
3343
3344 key_t key = IPC_PRIVATE;
3345 char *addr;
3346
3347 bool warn_on_failure = UseLargePages &&
3348 (!FLAG_IS_DEFAULT(UseLargePages) ||
3349 !FLAG_IS_DEFAULT(UseSHM) ||
3350 !FLAG_IS_DEFAULT(LargePageSizeInBytes));
3351 char msg[128];
3352
3353 // Create a large shared memory region to attach to based on size.
3354 // Currently, size is the total size of the heap
3355 int shmid = shmget(key, bytes, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W);
3356 if (shmid == -1) {
3357 // Possible reasons for shmget failure:
3358 // 1. shmmax is too small for Java heap.
3359 // > check shmmax value: cat /proc/sys/kernel/shmmax
3360 // > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax
3361 // 2. not enough large page memory.
3362 // > check available large pages: cat /proc/meminfo
3363 // > increase amount of large pages:
3364 // echo new_value > /proc/sys/vm/nr_hugepages
3365 // Note 1: different Linux may use different name for this property,
3366 // e.g. on Redhat AS-3 it is "hugetlb_pool".
3367 // Note 2: it's possible there's enough physical memory available but
3368 // they are so fragmented after a long run that they can't
3369 // coalesce into large pages. Try to reserve large pages when
3370 // the system is still "fresh".
3371 if (warn_on_failure) {
3372 jio_snprintf(msg, sizeof(msg), "Failed to reserve shared memory (errno = %d).", errno);
3373 warning("%s", msg);
3374 }
3375 return NULL;
3376 }
3377
3378 // attach to the region
3379 addr = (char*)shmat(shmid, req_addr, 0);
3380 int err = errno;
3381
3382 // Remove shmid. If shmat() is successful, the actual shared memory segment
3383 // will be deleted when it's detached by shmdt() or when the process
3384 // terminates. If shmat() is not successful this will remove the shared
3385 // segment immediately.
3386 shmctl(shmid, IPC_RMID, NULL);
3387
3388 if ((intptr_t)addr == -1) {
3389 if (warn_on_failure) {
3390 jio_snprintf(msg, sizeof(msg), "Failed to attach shared memory (errno = %d).", err);
3391 warning("%s", msg);
3392 }
3393 return NULL;
3394 }
3395
3396 return addr;
3397 }
3398
3399 static void warn_on_large_pages_failure(char* req_addr, size_t bytes,
3400 int error) {
3401 assert(error == ENOMEM, "Only expect to fail if no memory is available");
3402
3403 bool warn_on_failure = UseLargePages &&
3404 (!FLAG_IS_DEFAULT(UseLargePages) ||
3405 !FLAG_IS_DEFAULT(UseHugeTLBFS) ||
3406 !FLAG_IS_DEFAULT(LargePageSizeInBytes));
3407
3408 if (warn_on_failure) {
3409 char msg[128];
3410 jio_snprintf(msg, sizeof(msg), "Failed to reserve large pages memory req_addr: "
3411 PTR_FORMAT " bytes: " SIZE_FORMAT " (errno = %d).", req_addr, bytes, error);
3412 warning("%s", msg);
3413 }
3414 }
3415
3416 char* os::Linux::reserve_memory_special_huge_tlbfs_only(size_t bytes,
3417 char* req_addr,
3418 bool exec) {
3419 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages");
3420 assert(is_size_aligned(bytes, os::large_page_size()), "Unaligned size");
3421 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address");
3422
3423 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
3424 char* addr = (char*)::mmap(req_addr, bytes, prot,
3425 MAP_PRIVATE|MAP_ANONYMOUS|MAP_HUGETLB,
3426 -1, 0);
3427
3428 if (addr == MAP_FAILED) {
3429 warn_on_large_pages_failure(req_addr, bytes, errno);
3430 return NULL;
3431 }
3432
3433 assert(is_ptr_aligned(addr, os::large_page_size()), "Must be");
3434
3435 return addr;
3436 }
3437
3438 // Helper for os::Linux::reserve_memory_special_huge_tlbfs_mixed().
3439 // Allocate (using mmap, NO_RESERVE, with small pages) at either a given request address
3440 // (req_addr != NULL) or with a given alignment.
3441 // - bytes shall be a multiple of alignment.
3442 // - req_addr can be NULL. If not NULL, it must be a multiple of alignment.
3443 // - alignment sets the alignment at which memory shall be allocated.
3444 // It must be a multiple of allocation granularity.
3445 // Returns address of memory or NULL. If req_addr was not NULL, will only return
3446 // req_addr or NULL.
3447 static char* anon_mmap_aligned(size_t bytes, size_t alignment, char* req_addr) {
3448
3449 size_t extra_size = bytes;
3450 if (req_addr == NULL && alignment > 0) {
3451 extra_size += alignment;
3452 }
3453
3454 char* start = (char*) ::mmap(req_addr, extra_size, PROT_NONE,
3455 MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE,
3456 -1, 0);
3457 if (start == MAP_FAILED) {
3458 start = NULL;
3459 } else {
3460 if (req_addr != NULL) {
3461 if (start != req_addr) {
3462 ::munmap(start, extra_size);
3463 start = NULL;
3464 }
3465 } else {
3466 char* const start_aligned = (char*) align_ptr_up(start, alignment);
3467 char* const end_aligned = start_aligned + bytes;
3468 char* const end = start + extra_size;
3469 if (start_aligned > start) {
3470 ::munmap(start, start_aligned - start);
3471 }
3472 if (end_aligned < end) {
3473 ::munmap(end_aligned, end - end_aligned);
3474 }
3475 start = start_aligned;
3476 }
3477 }
3478 return start;
3479
3480 }
3481
3482 // Reserve memory using mmap(MAP_HUGETLB).
3483 // - bytes shall be a multiple of alignment.
3484 // - req_addr can be NULL. If not NULL, it must be a multiple of alignment.
3485 // - alignment sets the alignment at which memory shall be allocated.
3486 // It must be a multiple of allocation granularity.
3487 // Returns address of memory or NULL. If req_addr was not NULL, will only return
3488 // req_addr or NULL.
3489 char* os::Linux::reserve_memory_special_huge_tlbfs_mixed(size_t bytes,
3490 size_t alignment,
3491 char* req_addr,
3492 bool exec) {
3493 size_t large_page_size = os::large_page_size();
3494 assert(bytes >= large_page_size, "Shouldn't allocate large pages for small sizes");
3495
3496 assert(is_ptr_aligned(req_addr, alignment), "Must be");
3497 assert(is_size_aligned(bytes, alignment), "Must be");
3498
3499 // First reserve - but not commit - the address range in small pages.
3500 char* const start = anon_mmap_aligned(bytes, alignment, req_addr);
3501
3502 if (start == NULL) {
3503 return NULL;
3504 }
3505
3506 assert(is_ptr_aligned(start, alignment), "Must be");
3507
3508 char* end = start + bytes;
3509
3510 // Find the regions of the allocated chunk that can be promoted to large pages.
3511 char* lp_start = (char*)align_ptr_up(start, large_page_size);
3512 char* lp_end = (char*)align_ptr_down(end, large_page_size);
3513
3514 size_t lp_bytes = lp_end - lp_start;
3515
3516 assert(is_size_aligned(lp_bytes, large_page_size), "Must be");
3517
3518 if (lp_bytes == 0) {
3519 // The mapped region doesn't even span the start and the end of a large page.
3520 // Fall back to allocate a non-special area.
3521 ::munmap(start, end - start);
3522 return NULL;
3523 }
3524
3525 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
3526
3527 void* result;
3528
3529 // Commit small-paged leading area.
3530 if (start != lp_start) {
3531 result = ::mmap(start, lp_start - start, prot,
3532 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED,
3533 -1, 0);
3534 if (result == MAP_FAILED) {
3535 ::munmap(lp_start, end - lp_start);
3536 return NULL;
3537 }
3538 }
3539
3540 // Commit large-paged area.
3541 result = ::mmap(lp_start, lp_bytes, prot,
3542 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED|MAP_HUGETLB,
3543 -1, 0);
3544 if (result == MAP_FAILED) {
3545 warn_on_large_pages_failure(lp_start, lp_bytes, errno);
3546 // If the mmap above fails, the large pages region will be unmapped and we
3547 // have regions before and after with small pages. Release these regions.
3548 //
3549 // | mapped | unmapped | mapped |
3550 // ^ ^ ^ ^
3551 // start lp_start lp_end end
3552 //
3553 ::munmap(start, lp_start - start);
3554 ::munmap(lp_end, end - lp_end);
3555 return NULL;
3556 }
3557
3558 // Commit small-paged trailing area.
3559 if (lp_end != end) {
3560 result = ::mmap(lp_end, end - lp_end, prot,
3561 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED,
3562 -1, 0);
3563 if (result == MAP_FAILED) {
3564 ::munmap(start, lp_end - start);
3565 return NULL;
3566 }
3567 }
3568
3569 return start;
3570 }
3571
3572 char* os::Linux::reserve_memory_special_huge_tlbfs(size_t bytes,
3573 size_t alignment,
3574 char* req_addr,
3575 bool exec) {
3576 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages");
3577 assert(is_ptr_aligned(req_addr, alignment), "Must be");
3578 assert(is_size_aligned(alignment, os::vm_allocation_granularity()), "Must be");
3579 assert(is_power_of_2(os::large_page_size()), "Must be");
3580 assert(bytes >= os::large_page_size(), "Shouldn't allocate large pages for small sizes");
3581
3582 if (is_size_aligned(bytes, os::large_page_size()) && alignment <= os::large_page_size()) {
3583 return reserve_memory_special_huge_tlbfs_only(bytes, req_addr, exec);
3584 } else {
3585 return reserve_memory_special_huge_tlbfs_mixed(bytes, alignment, req_addr, exec);
3586 }
3587 }
3588
3589 char* os::reserve_memory_special(size_t bytes, size_t alignment,
3590 char* req_addr, bool exec) {
3591 assert(UseLargePages, "only for large pages");
3592
3593 char* addr;
3594 if (UseSHM) {
3595 addr = os::Linux::reserve_memory_special_shm(bytes, alignment, req_addr, exec);
3596 } else {
3597 assert(UseHugeTLBFS, "must be");
3598 addr = os::Linux::reserve_memory_special_huge_tlbfs(bytes, alignment, req_addr, exec);
3599 }
3600
3601 if (addr != NULL) {
3602 if (UseNUMAInterleaving) {
3603 numa_make_global(addr, bytes);
3604 }
3605
3606 // The memory is committed
3607 MemTracker::record_virtual_memory_reserve_and_commit((address)addr, bytes, CALLER_PC);
3608 }
3609
3610 return addr;
3611 }
3612
3613 bool os::Linux::release_memory_special_shm(char* base, size_t bytes) {
3614 // detaching the SHM segment will also delete it, see reserve_memory_special_shm()
3615 return shmdt(base) == 0;
3616 }
3617
3618 bool os::Linux::release_memory_special_huge_tlbfs(char* base, size_t bytes) {
3619 return pd_release_memory(base, bytes);
3620 }
3621
3622 bool os::release_memory_special(char* base, size_t bytes) {
3623 bool res;
3624 if (MemTracker::tracking_level() > NMT_minimal) {
3625 Tracker tkr = MemTracker::get_virtual_memory_release_tracker();
3626 res = os::Linux::release_memory_special_impl(base, bytes);
3627 if (res) {
3628 tkr.record((address)base, bytes);
3629 }
3630
3631 } else {
3632 res = os::Linux::release_memory_special_impl(base, bytes);
3633 }
3634 return res;
3635 }
3636
3637 bool os::Linux::release_memory_special_impl(char* base, size_t bytes) {
3638 assert(UseLargePages, "only for large pages");
3639 bool res;
3640
3641 if (UseSHM) {
3642 res = os::Linux::release_memory_special_shm(base, bytes);
3643 } else {
3644 assert(UseHugeTLBFS, "must be");
3645 res = os::Linux::release_memory_special_huge_tlbfs(base, bytes);
3646 }
3647 return res;
3648 }
3649
3650 size_t os::large_page_size() {
3651 return _large_page_size;
3652 }
3653
3654 // With SysV SHM the entire memory region must be allocated as shared
3655 // memory.
3656 // HugeTLBFS allows application to commit large page memory on demand.
3657 // However, when committing memory with HugeTLBFS fails, the region
3658 // that was supposed to be committed will lose the old reservation
3659 // and allow other threads to steal that memory region. Because of this
3660 // behavior we can't commit HugeTLBFS memory.
3661 bool os::can_commit_large_page_memory() {
3662 return UseTransparentHugePages;
3663 }
3664
3665 bool os::can_execute_large_page_memory() {
3666 return UseTransparentHugePages || UseHugeTLBFS;
3667 }
3668
3669 // Reserve memory at an arbitrary address, only if that area is
3670 // available (and not reserved for something else).
3671
3672 char* os::pd_attempt_reserve_memory_at(size_t bytes, char* requested_addr) {
3673 const int max_tries = 10;
3674 char* base[max_tries];
3675 size_t size[max_tries];
3676 const size_t gap = 0x000000;
3677
3678 // Assert only that the size is a multiple of the page size, since
3679 // that's all that mmap requires, and since that's all we really know
3680 // about at this low abstraction level. If we need higher alignment,
3681 // we can either pass an alignment to this method or verify alignment
3682 // in one of the methods further up the call chain. See bug 5044738.
3683 assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block");
3684
3685 // Repeatedly allocate blocks until the block is allocated at the
3686 // right spot. Give up after max_tries. Note that reserve_memory() will
3687 // automatically update _highest_vm_reserved_address if the call is
3688 // successful. The variable tracks the highest memory address every reserved
3689 // by JVM. It is used to detect heap-stack collision if running with
3690 // fixed-stack LinuxThreads. Because here we may attempt to reserve more
3691 // space than needed, it could confuse the collision detecting code. To
3692 // solve the problem, save current _highest_vm_reserved_address and
3693 // calculate the correct value before return.
3694 address old_highest = _highest_vm_reserved_address;
3695
3696 // Linux mmap allows caller to pass an address as hint; give it a try first,
3697 // if kernel honors the hint then we can return immediately.
3698 char * addr = anon_mmap(requested_addr, bytes, false);
3699 if (addr == requested_addr) {
3700 return requested_addr;
3701 }
3702
3703 if (addr != NULL) {
3704 // mmap() is successful but it fails to reserve at the requested address
3705 anon_munmap(addr, bytes);
3706 }
3707
3708 int i;
3709 for (i = 0; i < max_tries; ++i) {
3710 base[i] = reserve_memory(bytes);
3711
3712 if (base[i] != NULL) {
3713 // Is this the block we wanted?
3714 if (base[i] == requested_addr) {
3715 size[i] = bytes;
3716 break;
3717 }
3718
3719 // Does this overlap the block we wanted? Give back the overlapped
3720 // parts and try again.
3721
3722 ptrdiff_t top_overlap = requested_addr + (bytes + gap) - base[i];
3723 if (top_overlap >= 0 && (size_t)top_overlap < bytes) {
3724 unmap_memory(base[i], top_overlap);
3725 base[i] += top_overlap;
3726 size[i] = bytes - top_overlap;
3727 } else {
3728 ptrdiff_t bottom_overlap = base[i] + bytes - requested_addr;
3729 if (bottom_overlap >= 0 && (size_t)bottom_overlap < bytes) {
3730 unmap_memory(requested_addr, bottom_overlap);
3731 size[i] = bytes - bottom_overlap;
3732 } else {
3733 size[i] = bytes;
3734 }
3735 }
3736 }
3737 }
3738
3739 // Give back the unused reserved pieces.
3740
3741 for (int j = 0; j < i; ++j) {
3742 if (base[j] != NULL) {
3743 unmap_memory(base[j], size[j]);
3744 }
3745 }
3746
3747 if (i < max_tries) {
3748 _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes);
3749 return requested_addr;
3750 } else {
3751 _highest_vm_reserved_address = old_highest;
3752 return NULL;
3753 }
3754 }
3755
3756 size_t os::read(int fd, void *buf, unsigned int nBytes) {
3757 return ::read(fd, buf, nBytes);
3758 }
3759
3760 size_t os::read_at(int fd, void *buf, unsigned int nBytes, jlong offset) {
3761 return ::pread(fd, buf, nBytes, offset);
3762 }
3763
3764 // Short sleep, direct OS call.
3765 //
3766 // Note: certain versions of Linux CFS scheduler (since 2.6.23) do not guarantee
3767 // sched_yield(2) will actually give up the CPU:
3768 //
3769 // * Alone on this pariticular CPU, keeps running.
3770 // * Before the introduction of "skip_buddy" with "compat_yield" disabled
3771 // (pre 2.6.39).
3772 //
3773 // So calling this with 0 is an alternative.
3774 //
3775 void os::naked_short_sleep(jlong ms) {
3776 struct timespec req;
3777
3778 assert(ms < 1000, "Un-interruptable sleep, short time use only");
3779 req.tv_sec = 0;
3780 if (ms > 0) {
3781 req.tv_nsec = (ms % 1000) * 1000000;
3782 } else {
3783 req.tv_nsec = 1;
3784 }
3785
3786 nanosleep(&req, NULL);
3787
3788 return;
3789 }
3790
3791 // Sleep forever; naked call to OS-specific sleep; use with CAUTION
3792 void os::infinite_sleep() {
3793 while (true) { // sleep forever ...
3794 ::sleep(100); // ... 100 seconds at a time
3795 }
3796 }
3797
3798 // Used to convert frequent JVM_Yield() to nops
3799 bool os::dont_yield() {
3800 return DontYieldALot;
3801 }
3802
3803 void os::naked_yield() {
3804 sched_yield();
3805 }
3806
3807 ////////////////////////////////////////////////////////////////////////////////
3808 // thread priority support
3809
3810 // Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER
3811 // only supports dynamic priority, static priority must be zero. For real-time
3812 // applications, Linux supports SCHED_RR which allows static priority (1-99).
3813 // However, for large multi-threaded applications, SCHED_RR is not only slower
3814 // than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out
3815 // of 5 runs - Sep 2005).
3816 //
3817 // The following code actually changes the niceness of kernel-thread/LWP. It
3818 // has an assumption that setpriority() only modifies one kernel-thread/LWP,
3819 // not the entire user process, and user level threads are 1:1 mapped to kernel
3820 // threads. It has always been the case, but could change in the future. For
3821 // this reason, the code should not be used as default (ThreadPriorityPolicy=0).
3822 // It is only used when ThreadPriorityPolicy=1 and requires root privilege.
3823
3824 int os::java_to_os_priority[CriticalPriority + 1] = {
3825 19, // 0 Entry should never be used
3826
3827 4, // 1 MinPriority
3828 3, // 2
3829 2, // 3
3830
3831 1, // 4
3832 0, // 5 NormPriority
3833 -1, // 6
3834
3835 -2, // 7
3836 -3, // 8
3837 -4, // 9 NearMaxPriority
3838
3839 -5, // 10 MaxPriority
3840
3841 -5 // 11 CriticalPriority
3842 };
3843
3844 static int prio_init() {
3845 if (ThreadPriorityPolicy == 1) {
3846 // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1
3847 // if effective uid is not root. Perhaps, a more elegant way of doing
3848 // this is to test CAP_SYS_NICE capability, but that will require libcap.so
3849 if (geteuid() != 0) {
3850 if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) {
3851 warning("-XX:ThreadPriorityPolicy requires root privilege on Linux");
3852 }
3853 ThreadPriorityPolicy = 0;
3854 }
3855 }
3856 if (UseCriticalJavaThreadPriority) {
3857 os::java_to_os_priority[MaxPriority] = os::java_to_os_priority[CriticalPriority];
3858 }
3859 return 0;
3860 }
3861
3862 OSReturn os::set_native_priority(Thread* thread, int newpri) {
3863 if (!UseThreadPriorities || ThreadPriorityPolicy == 0) return OS_OK;
3864
3865 int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri);
3866 return (ret == 0) ? OS_OK : OS_ERR;
3867 }
3868
3869 OSReturn os::get_native_priority(const Thread* const thread,
3870 int *priority_ptr) {
3871 if (!UseThreadPriorities || ThreadPriorityPolicy == 0) {
3872 *priority_ptr = java_to_os_priority[NormPriority];
3873 return OS_OK;
3874 }
3875
3876 errno = 0;
3877 *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id());
3878 return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR);
3879 }
3880
3881 // Hint to the underlying OS that a task switch would not be good.
3882 // Void return because it's a hint and can fail.
3883 void os::hint_no_preempt() {}
3884
3885 ////////////////////////////////////////////////////////////////////////////////
3886 // suspend/resume support
3887
3888 // the low-level signal-based suspend/resume support is a remnant from the
3889 // old VM-suspension that used to be for java-suspension, safepoints etc,
3890 // within hotspot. Now there is a single use-case for this:
3891 // - calling get_thread_pc() on the VMThread by the flat-profiler task
3892 // that runs in the watcher thread.
3893 // The remaining code is greatly simplified from the more general suspension
3894 // code that used to be used.
3895 //
3896 // The protocol is quite simple:
3897 // - suspend:
3898 // - sends a signal to the target thread
3899 // - polls the suspend state of the osthread using a yield loop
3900 // - target thread signal handler (SR_handler) sets suspend state
3901 // and blocks in sigsuspend until continued
3902 // - resume:
3903 // - sets target osthread state to continue
3904 // - sends signal to end the sigsuspend loop in the SR_handler
3905 //
3906 // Note that the SR_lock plays no role in this suspend/resume protocol.
3907
3908 static void resume_clear_context(OSThread *osthread) {
3909 osthread->set_ucontext(NULL);
3910 osthread->set_siginfo(NULL);
3911 }
3912
3913 static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo,
3914 ucontext_t* context) {
3915 osthread->set_ucontext(context);
3916 osthread->set_siginfo(siginfo);
3917 }
3918
3919 // Handler function invoked when a thread's execution is suspended or
3920 // resumed. We have to be careful that only async-safe functions are
3921 // called here (Note: most pthread functions are not async safe and
3922 // should be avoided.)
3923 //
3924 // Note: sigwait() is a more natural fit than sigsuspend() from an
3925 // interface point of view, but sigwait() prevents the signal hander
3926 // from being run. libpthread would get very confused by not having
3927 // its signal handlers run and prevents sigwait()'s use with the
3928 // mutex granting granting signal.
3929 //
3930 // Currently only ever called on the VMThread and JavaThreads (PC sampling)
3931 //
3932 static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) {
3933 // Save and restore errno to avoid confusing native code with EINTR
3934 // after sigsuspend.
3935 int old_errno = errno;
3936
3937 Thread* thread = Thread::current();
3938 OSThread* osthread = thread->osthread();
3939 assert(thread->is_VM_thread() || thread->is_Java_thread(), "Must be VMThread or JavaThread");
3940
3941 os::SuspendResume::State current = osthread->sr.state();
3942 if (current == os::SuspendResume::SR_SUSPEND_REQUEST) {
3943 suspend_save_context(osthread, siginfo, context);
3944
3945 // attempt to switch the state, we assume we had a SUSPEND_REQUEST
3946 os::SuspendResume::State state = osthread->sr.suspended();
3947 if (state == os::SuspendResume::SR_SUSPENDED) {
3948 sigset_t suspend_set; // signals for sigsuspend()
3949
3950 // get current set of blocked signals and unblock resume signal
3951 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set);
3952 sigdelset(&suspend_set, SR_signum);
3953
3954 sr_semaphore.signal();
3955 // wait here until we are resumed
3956 while (1) {
3957 sigsuspend(&suspend_set);
3958
3959 os::SuspendResume::State result = osthread->sr.running();
3960 if (result == os::SuspendResume::SR_RUNNING) {
3961 sr_semaphore.signal();
3962 break;
3963 }
3964 }
3965
3966 } else if (state == os::SuspendResume::SR_RUNNING) {
3967 // request was cancelled, continue
3968 } else {
3969 ShouldNotReachHere();
3970 }
3971
3972 resume_clear_context(osthread);
3973 } else if (current == os::SuspendResume::SR_RUNNING) {
3974 // request was cancelled, continue
3975 } else if (current == os::SuspendResume::SR_WAKEUP_REQUEST) {
3976 // ignore
3977 } else {
3978 // ignore
3979 }
3980
3981 errno = old_errno;
3982 }
3983
3984
3985 static int SR_initialize() {
3986 struct sigaction act;
3987 char *s;
3988 // Get signal number to use for suspend/resume
3989 if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) {
3990 int sig = ::strtol(s, 0, 10);
3991 if (sig > 0 || sig < _NSIG) {
3992 SR_signum = sig;
3993 }
3994 }
3995
3996 assert(SR_signum > SIGSEGV && SR_signum > SIGBUS,
3997 "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769");
3998
3999 sigemptyset(&SR_sigset);
4000 sigaddset(&SR_sigset, SR_signum);
4001
4002 // Set up signal handler for suspend/resume
4003 act.sa_flags = SA_RESTART|SA_SIGINFO;
4004 act.sa_handler = (void (*)(int)) SR_handler;
4005
4006 // SR_signum is blocked by default.
4007 // 4528190 - We also need to block pthread restart signal (32 on all
4008 // supported Linux platforms). Note that LinuxThreads need to block
4009 // this signal for all threads to work properly. So we don't have
4010 // to use hard-coded signal number when setting up the mask.
4011 pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask);
4012
4013 if (sigaction(SR_signum, &act, 0) == -1) {
4014 return -1;
4015 }
4016
4017 // Save signal flag
4018 os::Linux::set_our_sigflags(SR_signum, act.sa_flags);
4019 return 0;
4020 }
4021
4022 static int sr_notify(OSThread* osthread) {
4023 int status = pthread_kill(osthread->pthread_id(), SR_signum);
4024 assert_status(status == 0, status, "pthread_kill");
4025 return status;
4026 }
4027
4028 // "Randomly" selected value for how long we want to spin
4029 // before bailing out on suspending a thread, also how often
4030 // we send a signal to a thread we want to resume
4031 static const int RANDOMLY_LARGE_INTEGER = 1000000;
4032 static const int RANDOMLY_LARGE_INTEGER2 = 100;
4033
4034 // returns true on success and false on error - really an error is fatal
4035 // but this seems the normal response to library errors
4036 static bool do_suspend(OSThread* osthread) {
4037 assert(osthread->sr.is_running(), "thread should be running");
4038 assert(!sr_semaphore.trywait(), "semaphore has invalid state");
4039
4040 // mark as suspended and send signal
4041 if (osthread->sr.request_suspend() != os::SuspendResume::SR_SUSPEND_REQUEST) {
4042 // failed to switch, state wasn't running?
4043 ShouldNotReachHere();
4044 return false;
4045 }
4046
4047 if (sr_notify(osthread) != 0) {
4048 ShouldNotReachHere();
4049 }
4050
4051 // managed to send the signal and switch to SUSPEND_REQUEST, now wait for SUSPENDED
4052 while (true) {
4053 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) {
4054 break;
4055 } else {
4056 // timeout
4057 os::SuspendResume::State cancelled = osthread->sr.cancel_suspend();
4058 if (cancelled == os::SuspendResume::SR_RUNNING) {
4059 return false;
4060 } else if (cancelled == os::SuspendResume::SR_SUSPENDED) {
4061 // make sure that we consume the signal on the semaphore as well
4062 sr_semaphore.wait();
4063 break;
4064 } else {
4065 ShouldNotReachHere();
4066 return false;
4067 }
4068 }
4069 }
4070
4071 guarantee(osthread->sr.is_suspended(), "Must be suspended");
4072 return true;
4073 }
4074
4075 static void do_resume(OSThread* osthread) {
4076 assert(osthread->sr.is_suspended(), "thread should be suspended");
4077 assert(!sr_semaphore.trywait(), "invalid semaphore state");
4078
4079 if (osthread->sr.request_wakeup() != os::SuspendResume::SR_WAKEUP_REQUEST) {
4080 // failed to switch to WAKEUP_REQUEST
4081 ShouldNotReachHere();
4082 return;
4083 }
4084
4085 while (true) {
4086 if (sr_notify(osthread) == 0) {
4087 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) {
4088 if (osthread->sr.is_running()) {
4089 return;
4090 }
4091 }
4092 } else {
4093 ShouldNotReachHere();
4094 }
4095 }
4096
4097 guarantee(osthread->sr.is_running(), "Must be running!");
4098 }
4099
4100 ///////////////////////////////////////////////////////////////////////////////////
4101 // signal handling (except suspend/resume)
4102
4103 // This routine may be used by user applications as a "hook" to catch signals.
4104 // The user-defined signal handler must pass unrecognized signals to this
4105 // routine, and if it returns true (non-zero), then the signal handler must
4106 // return immediately. If the flag "abort_if_unrecognized" is true, then this
4107 // routine will never retun false (zero), but instead will execute a VM panic
4108 // routine kill the process.
4109 //
4110 // If this routine returns false, it is OK to call it again. This allows
4111 // the user-defined signal handler to perform checks either before or after
4112 // the VM performs its own checks. Naturally, the user code would be making
4113 // a serious error if it tried to handle an exception (such as a null check
4114 // or breakpoint) that the VM was generating for its own correct operation.
4115 //
4116 // This routine may recognize any of the following kinds of signals:
4117 // SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1.
4118 // It should be consulted by handlers for any of those signals.
4119 //
4120 // The caller of this routine must pass in the three arguments supplied
4121 // to the function referred to in the "sa_sigaction" (not the "sa_handler")
4122 // field of the structure passed to sigaction(). This routine assumes that
4123 // the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART.
4124 //
4125 // Note that the VM will print warnings if it detects conflicting signal
4126 // handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers".
4127 //
4128 extern "C" JNIEXPORT int JVM_handle_linux_signal(int signo,
4129 siginfo_t* siginfo,
4130 void* ucontext,
4131 int abort_if_unrecognized);
4132
4133 void signalHandler(int sig, siginfo_t* info, void* uc) {
4134 assert(info != NULL && uc != NULL, "it must be old kernel");
4135 int orig_errno = errno; // Preserve errno value over signal handler.
4136 JVM_handle_linux_signal(sig, info, uc, true);
4137 errno = orig_errno;
4138 }
4139
4140
4141 // This boolean allows users to forward their own non-matching signals
4142 // to JVM_handle_linux_signal, harmlessly.
4143 bool os::Linux::signal_handlers_are_installed = false;
4144
4145 // For signal-chaining
4146 struct sigaction os::Linux::sigact[MAXSIGNUM];
4147 unsigned int os::Linux::sigs = 0;
4148 bool os::Linux::libjsig_is_loaded = false;
4149 typedef struct sigaction *(*get_signal_t)(int);
4150 get_signal_t os::Linux::get_signal_action = NULL;
4151
4152 struct sigaction* os::Linux::get_chained_signal_action(int sig) {
4153 struct sigaction *actp = NULL;
4154
4155 if (libjsig_is_loaded) {
4156 // Retrieve the old signal handler from libjsig
4157 actp = (*get_signal_action)(sig);
4158 }
4159 if (actp == NULL) {
4160 // Retrieve the preinstalled signal handler from jvm
4161 actp = get_preinstalled_handler(sig);
4162 }
4163
4164 return actp;
4165 }
4166
4167 static bool call_chained_handler(struct sigaction *actp, int sig,
4168 siginfo_t *siginfo, void *context) {
4169 // Call the old signal handler
4170 if (actp->sa_handler == SIG_DFL) {
4171 // It's more reasonable to let jvm treat it as an unexpected exception
4172 // instead of taking the default action.
4173 return false;
4174 } else if (actp->sa_handler != SIG_IGN) {
4175 if ((actp->sa_flags & SA_NODEFER) == 0) {
4176 // automaticlly block the signal
4177 sigaddset(&(actp->sa_mask), sig);
4178 }
4179
4180 sa_handler_t hand;
4181 sa_sigaction_t sa;
4182 bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0;
4183 // retrieve the chained handler
4184 if (siginfo_flag_set) {
4185 sa = actp->sa_sigaction;
4186 } else {
4187 hand = actp->sa_handler;
4188 }
4189
4190 if ((actp->sa_flags & SA_RESETHAND) != 0) {
4191 actp->sa_handler = SIG_DFL;
4192 }
4193
4194 // try to honor the signal mask
4195 sigset_t oset;
4196 pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset);
4197
4198 // call into the chained handler
4199 if (siginfo_flag_set) {
4200 (*sa)(sig, siginfo, context);
4201 } else {
4202 (*hand)(sig);
4203 }
4204
4205 // restore the signal mask
4206 pthread_sigmask(SIG_SETMASK, &oset, 0);
4207 }
4208 // Tell jvm's signal handler the signal is taken care of.
4209 return true;
4210 }
4211
4212 bool os::Linux::chained_handler(int sig, siginfo_t* siginfo, void* context) {
4213 bool chained = false;
4214 // signal-chaining
4215 if (UseSignalChaining) {
4216 struct sigaction *actp = get_chained_signal_action(sig);
4217 if (actp != NULL) {
4218 chained = call_chained_handler(actp, sig, siginfo, context);
4219 }
4220 }
4221 return chained;
4222 }
4223
4224 struct sigaction* os::Linux::get_preinstalled_handler(int sig) {
4225 if ((((unsigned int)1 << sig) & sigs) != 0) {
4226 return &sigact[sig];
4227 }
4228 return NULL;
4229 }
4230
4231 void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) {
4232 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4233 sigact[sig] = oldAct;
4234 sigs |= (unsigned int)1 << sig;
4235 }
4236
4237 // for diagnostic
4238 int os::Linux::sigflags[MAXSIGNUM];
4239
4240 int os::Linux::get_our_sigflags(int sig) {
4241 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4242 return sigflags[sig];
4243 }
4244
4245 void os::Linux::set_our_sigflags(int sig, int flags) {
4246 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4247 sigflags[sig] = flags;
4248 }
4249
4250 void os::Linux::set_signal_handler(int sig, bool set_installed) {
4251 // Check for overwrite.
4252 struct sigaction oldAct;
4253 sigaction(sig, (struct sigaction*)NULL, &oldAct);
4254
4255 void* oldhand = oldAct.sa_sigaction
4256 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction)
4257 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler);
4258 if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) &&
4259 oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) &&
4260 oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) {
4261 if (AllowUserSignalHandlers || !set_installed) {
4262 // Do not overwrite; user takes responsibility to forward to us.
4263 return;
4264 } else if (UseSignalChaining) {
4265 // save the old handler in jvm
4266 save_preinstalled_handler(sig, oldAct);
4267 // libjsig also interposes the sigaction() call below and saves the
4268 // old sigaction on it own.
4269 } else {
4270 fatal(err_msg("Encountered unexpected pre-existing sigaction handler "
4271 "%#lx for signal %d.", (long)oldhand, sig));
4272 }
4273 }
4274
4275 struct sigaction sigAct;
4276 sigfillset(&(sigAct.sa_mask));
4277 sigAct.sa_handler = SIG_DFL;
4278 if (!set_installed) {
4279 sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
4280 } else {
4281 sigAct.sa_sigaction = signalHandler;
4282 sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
4283 }
4284 // Save flags, which are set by ours
4285 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4286 sigflags[sig] = sigAct.sa_flags;
4287
4288 int ret = sigaction(sig, &sigAct, &oldAct);
4289 assert(ret == 0, "check");
4290
4291 void* oldhand2 = oldAct.sa_sigaction
4292 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction)
4293 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler);
4294 assert(oldhand2 == oldhand, "no concurrent signal handler installation");
4295 }
4296
4297 // install signal handlers for signals that HotSpot needs to
4298 // handle in order to support Java-level exception handling.
4299
4300 void os::Linux::install_signal_handlers() {
4301 if (!signal_handlers_are_installed) {
4302 signal_handlers_are_installed = true;
4303
4304 // signal-chaining
4305 typedef void (*signal_setting_t)();
4306 signal_setting_t begin_signal_setting = NULL;
4307 signal_setting_t end_signal_setting = NULL;
4308 begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
4309 dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting"));
4310 if (begin_signal_setting != NULL) {
4311 end_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
4312 dlsym(RTLD_DEFAULT, "JVM_end_signal_setting"));
4313 get_signal_action = CAST_TO_FN_PTR(get_signal_t,
4314 dlsym(RTLD_DEFAULT, "JVM_get_signal_action"));
4315 libjsig_is_loaded = true;
4316 assert(UseSignalChaining, "should enable signal-chaining");
4317 }
4318 if (libjsig_is_loaded) {
4319 // Tell libjsig jvm is setting signal handlers
4320 (*begin_signal_setting)();
4321 }
4322
4323 set_signal_handler(SIGSEGV, true);
4324 set_signal_handler(SIGPIPE, true);
4325 set_signal_handler(SIGBUS, true);
4326 set_signal_handler(SIGILL, true);
4327 set_signal_handler(SIGFPE, true);
4328 #if defined(PPC64)
4329 set_signal_handler(SIGTRAP, true);
4330 #endif
4331 set_signal_handler(SIGXFSZ, true);
4332
4333 if (libjsig_is_loaded) {
4334 // Tell libjsig jvm finishes setting signal handlers
4335 (*end_signal_setting)();
4336 }
4337
4338 // We don't activate signal checker if libjsig is in place, we trust ourselves
4339 // and if UserSignalHandler is installed all bets are off.
4340 // Log that signal checking is off only if -verbose:jni is specified.
4341 if (CheckJNICalls) {
4342 if (libjsig_is_loaded) {
4343 if (PrintJNIResolving) {
4344 tty->print_cr("Info: libjsig is activated, all active signal checking is disabled");
4345 }
4346 check_signals = false;
4347 }
4348 if (AllowUserSignalHandlers) {
4349 if (PrintJNIResolving) {
4350 tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled");
4351 }
4352 check_signals = false;
4353 }
4354 }
4355 }
4356 }
4357
4358 // This is the fastest way to get thread cpu time on Linux.
4359 // Returns cpu time (user+sys) for any thread, not only for current.
4360 // POSIX compliant clocks are implemented in the kernels 2.6.16+.
4361 // It might work on 2.6.10+ with a special kernel/glibc patch.
4362 // For reference, please, see IEEE Std 1003.1-2004:
4363 // http://www.unix.org/single_unix_specification
4364
4365 jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) {
4366 struct timespec tp;
4367 int rc = os::Linux::clock_gettime(clockid, &tp);
4368 assert(rc == 0, "clock_gettime is expected to return 0 code");
4369
4370 return (tp.tv_sec * NANOSECS_PER_SEC) + tp.tv_nsec;
4371 }
4372
4373 /////
4374 // glibc on Linux platform uses non-documented flag
4375 // to indicate, that some special sort of signal
4376 // trampoline is used.
4377 // We will never set this flag, and we should
4378 // ignore this flag in our diagnostic
4379 #ifdef SIGNIFICANT_SIGNAL_MASK
4380 #undef SIGNIFICANT_SIGNAL_MASK
4381 #endif
4382 #define SIGNIFICANT_SIGNAL_MASK (~0x04000000)
4383
4384 static const char* get_signal_handler_name(address handler,
4385 char* buf, int buflen) {
4386 int offset;
4387 bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset);
4388 if (found) {
4389 // skip directory names
4390 const char *p1, *p2;
4391 p1 = buf;
4392 size_t len = strlen(os::file_separator());
4393 while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len;
4394 jio_snprintf(buf, buflen, "%s+0x%x", p1, offset);
4395 } else {
4396 jio_snprintf(buf, buflen, PTR_FORMAT, handler);
4397 }
4398 return buf;
4399 }
4400
4401 static void print_signal_handler(outputStream* st, int sig,
4402 char* buf, size_t buflen) {
4403 struct sigaction sa;
4404
4405 sigaction(sig, NULL, &sa);
4406
4407 // See comment for SIGNIFICANT_SIGNAL_MASK define
4408 sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
4409
4410 st->print("%s: ", os::exception_name(sig, buf, buflen));
4411
4412 address handler = (sa.sa_flags & SA_SIGINFO)
4413 ? CAST_FROM_FN_PTR(address, sa.sa_sigaction)
4414 : CAST_FROM_FN_PTR(address, sa.sa_handler);
4415
4416 if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) {
4417 st->print("SIG_DFL");
4418 } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) {
4419 st->print("SIG_IGN");
4420 } else {
4421 st->print("[%s]", get_signal_handler_name(handler, buf, buflen));
4422 }
4423
4424 st->print(", sa_mask[0]=");
4425 os::Posix::print_signal_set_short(st, &sa.sa_mask);
4426
4427 address rh = VMError::get_resetted_sighandler(sig);
4428 // May be, handler was resetted by VMError?
4429 if (rh != NULL) {
4430 handler = rh;
4431 sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK;
4432 }
4433
4434 st->print(", sa_flags=");
4435 os::Posix::print_sa_flags(st, sa.sa_flags);
4436
4437 // Check: is it our handler?
4438 if (handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) ||
4439 handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) {
4440 // It is our signal handler
4441 // check for flags, reset system-used one!
4442 if ((int)sa.sa_flags != os::Linux::get_our_sigflags(sig)) {
4443 st->print(
4444 ", flags was changed from " PTR32_FORMAT ", consider using jsig library",
4445 os::Linux::get_our_sigflags(sig));
4446 }
4447 }
4448 st->cr();
4449 }
4450
4451
4452 #define DO_SIGNAL_CHECK(sig) \
4453 do { \
4454 if (!sigismember(&check_signal_done, sig)) { \
4455 os::Linux::check_signal_handler(sig); \
4456 } \
4457 } while (0)
4458
4459 // This method is a periodic task to check for misbehaving JNI applications
4460 // under CheckJNI, we can add any periodic checks here
4461
4462 void os::run_periodic_checks() {
4463 if (check_signals == false) return;
4464
4465 // SEGV and BUS if overridden could potentially prevent
4466 // generation of hs*.log in the event of a crash, debugging
4467 // such a case can be very challenging, so we absolutely
4468 // check the following for a good measure:
4469 DO_SIGNAL_CHECK(SIGSEGV);
4470 DO_SIGNAL_CHECK(SIGILL);
4471 DO_SIGNAL_CHECK(SIGFPE);
4472 DO_SIGNAL_CHECK(SIGBUS);
4473 DO_SIGNAL_CHECK(SIGPIPE);
4474 DO_SIGNAL_CHECK(SIGXFSZ);
4475 #if defined(PPC64)
4476 DO_SIGNAL_CHECK(SIGTRAP);
4477 #endif
4478
4479 // ReduceSignalUsage allows the user to override these handlers
4480 // see comments at the very top and jvm_solaris.h
4481 if (!ReduceSignalUsage) {
4482 DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL);
4483 DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL);
4484 DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL);
4485 DO_SIGNAL_CHECK(BREAK_SIGNAL);
4486 }
4487
4488 DO_SIGNAL_CHECK(SR_signum);
4489 DO_SIGNAL_CHECK(INTERRUPT_SIGNAL);
4490 }
4491
4492 typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *);
4493
4494 static os_sigaction_t os_sigaction = NULL;
4495
4496 void os::Linux::check_signal_handler(int sig) {
4497 char buf[O_BUFLEN];
4498 address jvmHandler = NULL;
4499
4500
4501 struct sigaction act;
4502 if (os_sigaction == NULL) {
4503 // only trust the default sigaction, in case it has been interposed
4504 os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction");
4505 if (os_sigaction == NULL) return;
4506 }
4507
4508 os_sigaction(sig, (struct sigaction*)NULL, &act);
4509
4510
4511 act.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
4512
4513 address thisHandler = (act.sa_flags & SA_SIGINFO)
4514 ? CAST_FROM_FN_PTR(address, act.sa_sigaction)
4515 : CAST_FROM_FN_PTR(address, act.sa_handler);
4516
4517
4518 switch (sig) {
4519 case SIGSEGV:
4520 case SIGBUS:
4521 case SIGFPE:
4522 case SIGPIPE:
4523 case SIGILL:
4524 case SIGXFSZ:
4525 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler);
4526 break;
4527
4528 case SHUTDOWN1_SIGNAL:
4529 case SHUTDOWN2_SIGNAL:
4530 case SHUTDOWN3_SIGNAL:
4531 case BREAK_SIGNAL:
4532 jvmHandler = (address)user_handler();
4533 break;
4534
4535 case INTERRUPT_SIGNAL:
4536 jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL);
4537 break;
4538
4539 default:
4540 if (sig == SR_signum) {
4541 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler);
4542 } else {
4543 return;
4544 }
4545 break;
4546 }
4547
4548 if (thisHandler != jvmHandler) {
4549 tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN));
4550 tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN));
4551 tty->print_cr(" found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN));
4552 // No need to check this sig any longer
4553 sigaddset(&check_signal_done, sig);
4554 // Running under non-interactive shell, SHUTDOWN2_SIGNAL will be reassigned SIG_IGN
4555 if (sig == SHUTDOWN2_SIGNAL && !isatty(fileno(stdin))) {
4556 tty->print_cr("Running in non-interactive shell, %s handler is replaced by shell",
4557 exception_name(sig, buf, O_BUFLEN));
4558 }
4559 } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) {
4560 tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN));
4561 tty->print("expected:" PTR32_FORMAT, os::Linux::get_our_sigflags(sig));
4562 tty->print_cr(" found:" PTR32_FORMAT, act.sa_flags);
4563 // No need to check this sig any longer
4564 sigaddset(&check_signal_done, sig);
4565 }
4566
4567 // Dump all the signal
4568 if (sigismember(&check_signal_done, sig)) {
4569 print_signal_handlers(tty, buf, O_BUFLEN);
4570 }
4571 }
4572
4573 extern void report_error(char* file_name, int line_no, char* title,
4574 char* format, ...);
4575
4576 extern bool signal_name(int signo, char* buf, size_t len);
4577
4578 const char* os::exception_name(int exception_code, char* buf, size_t size) {
4579 if (0 < exception_code && exception_code <= SIGRTMAX) {
4580 // signal
4581 if (!signal_name(exception_code, buf, size)) {
4582 jio_snprintf(buf, size, "SIG%d", exception_code);
4583 }
4584 return buf;
4585 } else {
4586 return NULL;
4587 }
4588 }
4589
4590 // this is called _before_ the most of global arguments have been parsed
4591 void os::init(void) {
4592 char dummy; // used to get a guess on initial stack address
4593 // first_hrtime = gethrtime();
4594
4595 // With LinuxThreads the JavaMain thread pid (primordial thread)
4596 // is different than the pid of the java launcher thread.
4597 // So, on Linux, the launcher thread pid is passed to the VM
4598 // via the sun.java.launcher.pid property.
4599 // Use this property instead of getpid() if it was correctly passed.
4600 // See bug 6351349.
4601 pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid();
4602
4603 _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid();
4604
4605 clock_tics_per_sec = sysconf(_SC_CLK_TCK);
4606
4607 init_random(1234567);
4608
4609 ThreadCritical::initialize();
4610
4611 Linux::set_page_size(sysconf(_SC_PAGESIZE));
4612 if (Linux::page_size() == -1) {
4613 fatal(err_msg("os_linux.cpp: os::init: sysconf failed (%s)",
4614 strerror(errno)));
4615 }
4616 init_page_sizes((size_t) Linux::page_size());
4617
4618 Linux::initialize_system_info();
4619
4620 // main_thread points to the aboriginal thread
4621 Linux::_main_thread = pthread_self();
4622
4623 Linux::clock_init();
4624 initial_time_count = javaTimeNanos();
4625
4626 // pthread_condattr initialization for monotonic clock
4627 int status;
4628 pthread_condattr_t* _condattr = os::Linux::condAttr();
4629 if ((status = pthread_condattr_init(_condattr)) != 0) {
4630 fatal(err_msg("pthread_condattr_init: %s", strerror(status)));
4631 }
4632 // Only set the clock if CLOCK_MONOTONIC is available
4633 if (os::supports_monotonic_clock()) {
4634 if ((status = pthread_condattr_setclock(_condattr, CLOCK_MONOTONIC)) != 0) {
4635 if (status == EINVAL) {
4636 warning("Unable to use monotonic clock with relative timed-waits" \
4637 " - changes to the time-of-day clock may have adverse affects");
4638 } else {
4639 fatal(err_msg("pthread_condattr_setclock: %s", strerror(status)));
4640 }
4641 }
4642 }
4643 // else it defaults to CLOCK_REALTIME
4644
4645 // If the pagesize of the VM is greater than 8K determine the appropriate
4646 // number of initial guard pages. The user can change this with the
4647 // command line arguments, if needed.
4648 if (vm_page_size() > (int)Linux::vm_default_page_size()) {
4649 StackYellowPages = 1;
4650 StackRedPages = 1;
4651 StackShadowPages = round_to((StackShadowPages*Linux::vm_default_page_size()), vm_page_size()) / vm_page_size();
4652 }
4653
4654 // retrieve entry point for pthread_setname_np
4655 Linux::_pthread_setname_np =
4656 (int(*)(pthread_t, const char*))dlsym(RTLD_DEFAULT, "pthread_setname_np");
4657
4658 }
4659
4660 // To install functions for atexit system call
4661 extern "C" {
4662 static void perfMemory_exit_helper() {
4663 perfMemory_exit();
4664 }
4665 }
4666
4667 // this is called _after_ the global arguments have been parsed
4668 jint os::init_2(void) {
4669 Linux::fast_thread_clock_init();
4670
4671 // Allocate a single page and mark it as readable for safepoint polling
4672 address polling_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
4673 guarantee(polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page");
4674
4675 os::set_polling_page(polling_page);
4676
4677 #ifndef PRODUCT
4678 if (Verbose && PrintMiscellaneous) {
4679 tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n",
4680 (intptr_t)polling_page);
4681 }
4682 #endif
4683
4684 if (!UseMembar) {
4685 address mem_serialize_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
4686 guarantee(mem_serialize_page != MAP_FAILED, "mmap Failed for memory serialize page");
4687 os::set_memory_serialize_page(mem_serialize_page);
4688
4689 #ifndef PRODUCT
4690 if (Verbose && PrintMiscellaneous) {
4691 tty->print("[Memory Serialize Page address: " INTPTR_FORMAT "]\n",
4692 (intptr_t)mem_serialize_page);
4693 }
4694 #endif
4695 }
4696
4697 // initialize suspend/resume support - must do this before signal_sets_init()
4698 if (SR_initialize() != 0) {
4699 perror("SR_initialize failed");
4700 return JNI_ERR;
4701 }
4702
4703 Linux::signal_sets_init();
4704 Linux::install_signal_handlers();
4705
4706 // Check minimum allowable stack size for thread creation and to initialize
4707 // the java system classes, including StackOverflowError - depends on page
4708 // size. Add a page for compiler2 recursion in main thread.
4709 // Add in 2*BytesPerWord times page size to account for VM stack during
4710 // class initialization depending on 32 or 64 bit VM.
4711 os::Linux::min_stack_allowed = MAX2(os::Linux::min_stack_allowed,
4712 (size_t)(StackYellowPages+StackRedPages+StackShadowPages) * Linux::page_size() +
4713 (2*BytesPerWord COMPILER2_PRESENT(+1)) * Linux::vm_default_page_size());
4714
4715 size_t threadStackSizeInBytes = ThreadStackSize * K;
4716 if (threadStackSizeInBytes != 0 &&
4717 threadStackSizeInBytes < os::Linux::min_stack_allowed) {
4718 tty->print_cr("\nThe stack size specified is too small, "
4719 "Specify at least %dk",
4720 os::Linux::min_stack_allowed/ K);
4721 return JNI_ERR;
4722 }
4723
4724 // Make the stack size a multiple of the page size so that
4725 // the yellow/red zones can be guarded.
4726 JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes,
4727 vm_page_size()));
4728
4729 Linux::capture_initial_stack(JavaThread::stack_size_at_create());
4730
4731 #if defined(IA32)
4732 workaround_expand_exec_shield_cs_limit();
4733 #endif
4734
4735 Linux::libpthread_init();
4736 if (PrintMiscellaneous && (Verbose || WizardMode)) {
4737 tty->print_cr("[HotSpot is running with %s, %s(%s)]\n",
4738 Linux::glibc_version(), Linux::libpthread_version(),
4739 Linux::is_floating_stack() ? "floating stack" : "fixed stack");
4740 }
4741
4742 if (UseNUMA) {
4743 if (!Linux::libnuma_init()) {
4744 UseNUMA = false;
4745 } else {
4746 if ((Linux::numa_max_node() < 1)) {
4747 // There's only one node(they start from 0), disable NUMA.
4748 UseNUMA = false;
4749 }
4750 }
4751 // With SHM and HugeTLBFS large pages we cannot uncommit a page, so there's no way
4752 // we can make the adaptive lgrp chunk resizing work. If the user specified
4753 // both UseNUMA and UseLargePages (or UseSHM/UseHugeTLBFS) on the command line - warn and
4754 // disable adaptive resizing.
4755 if (UseNUMA && UseLargePages && !can_commit_large_page_memory()) {
4756 if (FLAG_IS_DEFAULT(UseNUMA)) {
4757 UseNUMA = false;
4758 } else {
4759 if (FLAG_IS_DEFAULT(UseLargePages) &&
4760 FLAG_IS_DEFAULT(UseSHM) &&
4761 FLAG_IS_DEFAULT(UseHugeTLBFS)) {
4762 UseLargePages = false;
4763 } else if (UseAdaptiveSizePolicy || UseAdaptiveNUMAChunkSizing) {
4764 warning("UseNUMA is not fully compatible with SHM/HugeTLBFS large pages, disabling adaptive resizing (-XX:-UseAdaptiveSizePolicy -XX:-UseAdaptiveNUMAChunkSizing)");
4765 UseAdaptiveSizePolicy = false;
4766 UseAdaptiveNUMAChunkSizing = false;
4767 }
4768 }
4769 }
4770 if (!UseNUMA && ForceNUMA) {
4771 UseNUMA = true;
4772 }
4773 }
4774
4775 if (MaxFDLimit) {
4776 // set the number of file descriptors to max. print out error
4777 // if getrlimit/setrlimit fails but continue regardless.
4778 struct rlimit nbr_files;
4779 int status = getrlimit(RLIMIT_NOFILE, &nbr_files);
4780 if (status != 0) {
4781 if (PrintMiscellaneous && (Verbose || WizardMode)) {
4782 perror("os::init_2 getrlimit failed");
4783 }
4784 } else {
4785 nbr_files.rlim_cur = nbr_files.rlim_max;
4786 status = setrlimit(RLIMIT_NOFILE, &nbr_files);
4787 if (status != 0) {
4788 if (PrintMiscellaneous && (Verbose || WizardMode)) {
4789 perror("os::init_2 setrlimit failed");
4790 }
4791 }
4792 }
4793 }
4794
4795 // Initialize lock used to serialize thread creation (see os::create_thread)
4796 Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false));
4797
4798 // at-exit methods are called in the reverse order of their registration.
4799 // atexit functions are called on return from main or as a result of a
4800 // call to exit(3C). There can be only 32 of these functions registered
4801 // and atexit() does not set errno.
4802
4803 if (PerfAllowAtExitRegistration) {
4804 // only register atexit functions if PerfAllowAtExitRegistration is set.
4805 // atexit functions can be delayed until process exit time, which
4806 // can be problematic for embedded VM situations. Embedded VMs should
4807 // call DestroyJavaVM() to assure that VM resources are released.
4808
4809 // note: perfMemory_exit_helper atexit function may be removed in
4810 // the future if the appropriate cleanup code can be added to the
4811 // VM_Exit VMOperation's doit method.
4812 if (atexit(perfMemory_exit_helper) != 0) {
4813 warning("os::init_2 atexit(perfMemory_exit_helper) failed");
4814 }
4815 }
4816
4817 // initialize thread priority policy
4818 prio_init();
4819
4820 return JNI_OK;
4821 }
4822
4823 // Mark the polling page as unreadable
4824 void os::make_polling_page_unreadable(void) {
4825 if (!guard_memory((char*)_polling_page, Linux::page_size())) {
4826 fatal("Could not disable polling page");
4827 }
4828 }
4829
4830 // Mark the polling page as readable
4831 void os::make_polling_page_readable(void) {
4832 if (!linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) {
4833 fatal("Could not enable polling page");
4834 }
4835 }
4836
4837 int os::active_processor_count() {
4838 // Linux doesn't yet have a (official) notion of processor sets,
4839 // so just return the number of online processors.
4840 int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN);
4841 assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check");
4842 return online_cpus;
4843 }
4844
4845 void os::set_native_thread_name(const char *name) {
4846 if (Linux::_pthread_setname_np) {
4847 char buf [16]; // according to glibc manpage, 16 chars incl. '/0'
4848 snprintf(buf, sizeof(buf), "%s", name);
4849 buf[sizeof(buf) - 1] = '\0';
4850 const int rc = Linux::_pthread_setname_np(pthread_self(), buf);
4851 // ERANGE should not happen; all other errors should just be ignored.
4852 assert(rc != ERANGE, "pthread_setname_np failed");
4853 }
4854 }
4855
4856 bool os::distribute_processes(uint length, uint* distribution) {
4857 // Not yet implemented.
4858 return false;
4859 }
4860
4861 bool os::bind_to_processor(uint processor_id) {
4862 // Not yet implemented.
4863 return false;
4864 }
4865
4866 ///
4867
4868 void os::SuspendedThreadTask::internal_do_task() {
4869 if (do_suspend(_thread->osthread())) {
4870 SuspendedThreadTaskContext context(_thread, _thread->osthread()->ucontext());
4871 do_task(context);
4872 do_resume(_thread->osthread());
4873 }
4874 }
4875
4876 class PcFetcher : public os::SuspendedThreadTask {
4877 public:
4878 PcFetcher(Thread* thread) : os::SuspendedThreadTask(thread) {}
4879 ExtendedPC result();
4880 protected:
4881 void do_task(const os::SuspendedThreadTaskContext& context);
4882 private:
4883 ExtendedPC _epc;
4884 };
4885
4886 ExtendedPC PcFetcher::result() {
4887 guarantee(is_done(), "task is not done yet.");
4888 return _epc;
4889 }
4890
4891 void PcFetcher::do_task(const os::SuspendedThreadTaskContext& context) {
4892 Thread* thread = context.thread();
4893 OSThread* osthread = thread->osthread();
4894 if (osthread->ucontext() != NULL) {
4895 _epc = os::Linux::ucontext_get_pc((ucontext_t *) context.ucontext());
4896 } else {
4897 // NULL context is unexpected, double-check this is the VMThread
4898 guarantee(thread->is_VM_thread(), "can only be called for VMThread");
4899 }
4900 }
4901
4902 // Suspends the target using the signal mechanism and then grabs the PC before
4903 // resuming the target. Used by the flat-profiler only
4904 ExtendedPC os::get_thread_pc(Thread* thread) {
4905 // Make sure that it is called by the watcher for the VMThread
4906 assert(Thread::current()->is_Watcher_thread(), "Must be watcher");
4907 assert(thread->is_VM_thread(), "Can only be called for VMThread");
4908
4909 PcFetcher fetcher(thread);
4910 fetcher.run();
4911 return fetcher.result();
4912 }
4913
4914 int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond,
4915 pthread_mutex_t *_mutex,
4916 const struct timespec *_abstime) {
4917 if (is_NPTL()) {
4918 return pthread_cond_timedwait(_cond, _mutex, _abstime);
4919 } else {
4920 // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control
4921 // word back to default 64bit precision if condvar is signaled. Java
4922 // wants 53bit precision. Save and restore current value.
4923 int fpu = get_fpu_control_word();
4924 int status = pthread_cond_timedwait(_cond, _mutex, _abstime);
4925 set_fpu_control_word(fpu);
4926 return status;
4927 }
4928 }
4929
4930 ////////////////////////////////////////////////////////////////////////////////
4931 // debug support
4932
4933 bool os::find(address addr, outputStream* st) {
4934 Dl_info dlinfo;
4935 memset(&dlinfo, 0, sizeof(dlinfo));
4936 if (dladdr(addr, &dlinfo) != 0) {
4937 st->print(PTR_FORMAT ": ", addr);
4938 if (dlinfo.dli_sname != NULL && dlinfo.dli_saddr != NULL) {
4939 st->print("%s+%#x", dlinfo.dli_sname,
4940 addr - (intptr_t)dlinfo.dli_saddr);
4941 } else if (dlinfo.dli_fbase != NULL) {
4942 st->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase);
4943 } else {
4944 st->print("<absolute address>");
4945 }
4946 if (dlinfo.dli_fname != NULL) {
4947 st->print(" in %s", dlinfo.dli_fname);
4948 }
4949 if (dlinfo.dli_fbase != NULL) {
4950 st->print(" at " PTR_FORMAT, dlinfo.dli_fbase);
4951 }
4952 st->cr();
4953
4954 if (Verbose) {
4955 // decode some bytes around the PC
4956 address begin = clamp_address_in_page(addr-40, addr, os::vm_page_size());
4957 address end = clamp_address_in_page(addr+40, addr, os::vm_page_size());
4958 address lowest = (address) dlinfo.dli_sname;
4959 if (!lowest) lowest = (address) dlinfo.dli_fbase;
4960 if (begin < lowest) begin = lowest;
4961 Dl_info dlinfo2;
4962 if (dladdr(end, &dlinfo2) != 0 && dlinfo2.dli_saddr != dlinfo.dli_saddr
4963 && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin) {
4964 end = (address) dlinfo2.dli_saddr;
4965 }
4966 Disassembler::decode(begin, end, st);
4967 }
4968 return true;
4969 }
4970 return false;
4971 }
4972
4973 ////////////////////////////////////////////////////////////////////////////////
4974 // misc
4975
4976 // This does not do anything on Linux. This is basically a hook for being
4977 // able to use structured exception handling (thread-local exception filters)
4978 // on, e.g., Win32.
4979 void
4980 os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method,
4981 JavaCallArguments* args, Thread* thread) {
4982 f(value, method, args, thread);
4983 }
4984
4985 void os::print_statistics() {
4986 }
4987
4988 int os::message_box(const char* title, const char* message) {
4989 int i;
4990 fdStream err(defaultStream::error_fd());
4991 for (i = 0; i < 78; i++) err.print_raw("=");
4992 err.cr();
4993 err.print_raw_cr(title);
4994 for (i = 0; i < 78; i++) err.print_raw("-");
4995 err.cr();
4996 err.print_raw_cr(message);
4997 for (i = 0; i < 78; i++) err.print_raw("=");
4998 err.cr();
4999
5000 char buf[16];
5001 // Prevent process from exiting upon "read error" without consuming all CPU
5002 while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); }
5003
5004 return buf[0] == 'y' || buf[0] == 'Y';
5005 }
5006
5007 int os::stat(const char *path, struct stat *sbuf) {
5008 char pathbuf[MAX_PATH];
5009 if (strlen(path) > MAX_PATH - 1) {
5010 errno = ENAMETOOLONG;
5011 return -1;
5012 }
5013 os::native_path(strcpy(pathbuf, path));
5014 return ::stat(pathbuf, sbuf);
5015 }
5016
5017 bool os::check_heap(bool force) {
5018 return true;
5019 }
5020
5021 // Is a (classpath) directory empty?
5022 bool os::dir_is_empty(const char* path) {
5023 DIR *dir = NULL;
5024 struct dirent *ptr;
5025
5026 dir = opendir(path);
5027 if (dir == NULL) return true;
5028
5029 // Scan the directory
5030 bool result = true;
5031 char buf[sizeof(struct dirent) + MAX_PATH];
5032 while (result && (ptr = ::readdir(dir)) != NULL) {
5033 if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) {
5034 result = false;
5035 }
5036 }
5037 closedir(dir);
5038 return result;
5039 }
5040
5041 // This code originates from JDK's sysOpen and open64_w
5042 // from src/solaris/hpi/src/system_md.c
5043
5044 int os::open(const char *path, int oflag, int mode) {
5045 if (strlen(path) > MAX_PATH - 1) {
5046 errno = ENAMETOOLONG;
5047 return -1;
5048 }
5049
5050 // All file descriptors that are opened in the Java process and not
5051 // specifically destined for a subprocess should have the close-on-exec
5052 // flag set. If we don't set it, then careless 3rd party native code
5053 // might fork and exec without closing all appropriate file descriptors
5054 // (e.g. as we do in closeDescriptors in UNIXProcess.c), and this in
5055 // turn might:
5056 //
5057 // - cause end-of-file to fail to be detected on some file
5058 // descriptors, resulting in mysterious hangs, or
5059 //
5060 // - might cause an fopen in the subprocess to fail on a system
5061 // suffering from bug 1085341.
5062 //
5063 // (Yes, the default setting of the close-on-exec flag is a Unix
5064 // design flaw)
5065 //
5066 // See:
5067 // 1085341: 32-bit stdio routines should support file descriptors >255
5068 // 4843136: (process) pipe file descriptor from Runtime.exec not being closed
5069 // 6339493: (process) Runtime.exec does not close all file descriptors on Solaris 9
5070 //
5071 // Modern Linux kernels (after 2.6.23 2007) support O_CLOEXEC with open().
5072 // O_CLOEXEC is preferable to using FD_CLOEXEC on an open file descriptor
5073 // because it saves a system call and removes a small window where the flag
5074 // is unset. On ancient Linux kernels the O_CLOEXEC flag will be ignored
5075 // and we fall back to using FD_CLOEXEC (see below).
5076 #ifdef O_CLOEXEC
5077 oflag |= O_CLOEXEC;
5078 #endif
5079
5080 int fd = ::open64(path, oflag, mode);
5081 if (fd == -1) return -1;
5082
5083 //If the open succeeded, the file might still be a directory
5084 {
5085 struct stat64 buf64;
5086 int ret = ::fstat64(fd, &buf64);
5087 int st_mode = buf64.st_mode;
5088
5089 if (ret != -1) {
5090 if ((st_mode & S_IFMT) == S_IFDIR) {
5091 errno = EISDIR;
5092 ::close(fd);
5093 return -1;
5094 }
5095 } else {
5096 ::close(fd);
5097 return -1;
5098 }
5099 }
5100
5101 #ifdef FD_CLOEXEC
5102 // Validate that the use of the O_CLOEXEC flag on open above worked.
5103 // With recent kernels, we will perform this check exactly once.
5104 static sig_atomic_t O_CLOEXEC_is_known_to_work = 0;
5105 if (!O_CLOEXEC_is_known_to_work) {
5106 int flags = ::fcntl(fd, F_GETFD);
5107 if (flags != -1) {
5108 if ((flags & FD_CLOEXEC) != 0)
5109 O_CLOEXEC_is_known_to_work = 1;
5110 else
5111 ::fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
5112 }
5113 }
5114 #endif
5115
5116 return fd;
5117 }
5118
5119
5120 // create binary file, rewriting existing file if required
5121 int os::create_binary_file(const char* path, bool rewrite_existing) {
5122 int oflags = O_WRONLY | O_CREAT;
5123 if (!rewrite_existing) {
5124 oflags |= O_EXCL;
5125 }
5126 return ::open64(path, oflags, S_IREAD | S_IWRITE);
5127 }
5128
5129 // return current position of file pointer
5130 jlong os::current_file_offset(int fd) {
5131 return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR);
5132 }
5133
5134 // move file pointer to the specified offset
5135 jlong os::seek_to_file_offset(int fd, jlong offset) {
5136 return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET);
5137 }
5138
5139 // This code originates from JDK's sysAvailable
5140 // from src/solaris/hpi/src/native_threads/src/sys_api_td.c
5141
5142 int os::available(int fd, jlong *bytes) {
5143 jlong cur, end;
5144 int mode;
5145 struct stat64 buf64;
5146
5147 if (::fstat64(fd, &buf64) >= 0) {
5148 mode = buf64.st_mode;
5149 if (S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) {
5150 // XXX: is the following call interruptible? If so, this might
5151 // need to go through the INTERRUPT_IO() wrapper as for other
5152 // blocking, interruptible calls in this file.
5153 int n;
5154 if (::ioctl(fd, FIONREAD, &n) >= 0) {
5155 *bytes = n;
5156 return 1;
5157 }
5158 }
5159 }
5160 if ((cur = ::lseek64(fd, 0L, SEEK_CUR)) == -1) {
5161 return 0;
5162 } else if ((end = ::lseek64(fd, 0L, SEEK_END)) == -1) {
5163 return 0;
5164 } else if (::lseek64(fd, cur, SEEK_SET) == -1) {
5165 return 0;
5166 }
5167 *bytes = end - cur;
5168 return 1;
5169 }
5170
5171 // Map a block of memory.
5172 char* os::pd_map_memory(int fd, const char* file_name, size_t file_offset,
5173 char *addr, size_t bytes, bool read_only,
5174 bool allow_exec) {
5175 int prot;
5176 int flags = MAP_PRIVATE;
5177
5178 if (read_only) {
5179 prot = PROT_READ;
5180 } else {
5181 prot = PROT_READ | PROT_WRITE;
5182 }
5183
5184 if (allow_exec) {
5185 prot |= PROT_EXEC;
5186 }
5187
5188 if (addr != NULL) {
5189 flags |= MAP_FIXED;
5190 }
5191
5192 char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags,
5193 fd, file_offset);
5194 if (mapped_address == MAP_FAILED) {
5195 return NULL;
5196 }
5197 return mapped_address;
5198 }
5199
5200
5201 // Remap a block of memory.
5202 char* os::pd_remap_memory(int fd, const char* file_name, size_t file_offset,
5203 char *addr, size_t bytes, bool read_only,
5204 bool allow_exec) {
5205 // same as map_memory() on this OS
5206 return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only,
5207 allow_exec);
5208 }
5209
5210
5211 // Unmap a block of memory.
5212 bool os::pd_unmap_memory(char* addr, size_t bytes) {
5213 return munmap(addr, bytes) == 0;
5214 }
5215
5216 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time);
5217
5218 static clockid_t thread_cpu_clockid(Thread* thread) {
5219 pthread_t tid = thread->osthread()->pthread_id();
5220 clockid_t clockid;
5221
5222 // Get thread clockid
5223 int rc = os::Linux::pthread_getcpuclockid(tid, &clockid);
5224 assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code");
5225 return clockid;
5226 }
5227
5228 // current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool)
5229 // are used by JVM M&M and JVMTI to get user+sys or user CPU time
5230 // of a thread.
5231 //
5232 // current_thread_cpu_time() and thread_cpu_time(Thread*) returns
5233 // the fast estimate available on the platform.
5234
5235 jlong os::current_thread_cpu_time() {
5236 if (os::Linux::supports_fast_thread_cpu_time()) {
5237 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
5238 } else {
5239 // return user + sys since the cost is the same
5240 return slow_thread_cpu_time(Thread::current(), true /* user + sys */);
5241 }
5242 }
5243
5244 jlong os::thread_cpu_time(Thread* thread) {
5245 // consistent with what current_thread_cpu_time() returns
5246 if (os::Linux::supports_fast_thread_cpu_time()) {
5247 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread));
5248 } else {
5249 return slow_thread_cpu_time(thread, true /* user + sys */);
5250 }
5251 }
5252
5253 jlong os::current_thread_cpu_time(bool user_sys_cpu_time) {
5254 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
5255 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
5256 } else {
5257 return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time);
5258 }
5259 }
5260
5261 jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
5262 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
5263 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread));
5264 } else {
5265 return slow_thread_cpu_time(thread, user_sys_cpu_time);
5266 }
5267 }
5268
5269 // -1 on error.
5270 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
5271 pid_t tid = thread->osthread()->thread_id();
5272 char *s;
5273 char stat[2048];
5274 int statlen;
5275 char proc_name[64];
5276 int count;
5277 long sys_time, user_time;
5278 char cdummy;
5279 int idummy;
5280 long ldummy;
5281 FILE *fp;
5282
5283 snprintf(proc_name, 64, "/proc/self/task/%d/stat", tid);
5284 fp = fopen(proc_name, "r");
5285 if (fp == NULL) return -1;
5286 statlen = fread(stat, 1, 2047, fp);
5287 stat[statlen] = '\0';
5288 fclose(fp);
5289
5290 // Skip pid and the command string. Note that we could be dealing with
5291 // weird command names, e.g. user could decide to rename java launcher
5292 // to "java 1.4.2 :)", then the stat file would look like
5293 // 1234 (java 1.4.2 :)) R ... ...
5294 // We don't really need to know the command string, just find the last
5295 // occurrence of ")" and then start parsing from there. See bug 4726580.
5296 s = strrchr(stat, ')');
5297 if (s == NULL) return -1;
5298
5299 // Skip blank chars
5300 do { s++; } while (s && isspace(*s));
5301
5302 count = sscanf(s,"%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu",
5303 &cdummy, &idummy, &idummy, &idummy, &idummy, &idummy,
5304 &ldummy, &ldummy, &ldummy, &ldummy, &ldummy,
5305 &user_time, &sys_time);
5306 if (count != 13) return -1;
5307 if (user_sys_cpu_time) {
5308 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec);
5309 } else {
5310 return (jlong)user_time * (1000000000 / clock_tics_per_sec);
5311 }
5312 }
5313
5314 void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
5315 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits
5316 info_ptr->may_skip_backward = false; // elapsed time not wall time
5317 info_ptr->may_skip_forward = false; // elapsed time not wall time
5318 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned
5319 }
5320
5321 void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
5322 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits
5323 info_ptr->may_skip_backward = false; // elapsed time not wall time
5324 info_ptr->may_skip_forward = false; // elapsed time not wall time
5325 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned
5326 }
5327
5328 bool os::is_thread_cpu_time_supported() {
5329 return true;
5330 }
5331
5332 // System loadavg support. Returns -1 if load average cannot be obtained.
5333 // Linux doesn't yet have a (official) notion of processor sets,
5334 // so just return the system wide load average.
5335 int os::loadavg(double loadavg[], int nelem) {
5336 return ::getloadavg(loadavg, nelem);
5337 }
5338
5339 void os::pause() {
5340 char filename[MAX_PATH];
5341 if (PauseAtStartupFile && PauseAtStartupFile[0]) {
5342 jio_snprintf(filename, MAX_PATH, PauseAtStartupFile);
5343 } else {
5344 jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id());
5345 }
5346
5347 int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
5348 if (fd != -1) {
5349 struct stat buf;
5350 ::close(fd);
5351 while (::stat(filename, &buf) == 0) {
5352 (void)::poll(NULL, 0, 100);
5353 }
5354 } else {
5355 jio_fprintf(stderr,
5356 "Could not open pause file '%s', continuing immediately.\n", filename);
5357 }
5358 }
5359
5360
5361 // Refer to the comments in os_solaris.cpp park-unpark. The next two
5362 // comment paragraphs are worth repeating here:
5363 //
5364 // Assumption:
5365 // Only one parker can exist on an event, which is why we allocate
5366 // them per-thread. Multiple unparkers can coexist.
5367 //
5368 // _Event serves as a restricted-range semaphore.
5369 // -1 : thread is blocked, i.e. there is a waiter
5370 // 0 : neutral: thread is running or ready,
5371 // could have been signaled after a wait started
5372 // 1 : signaled - thread is running or ready
5373 //
5374 // Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can
5375 // hang indefinitely. For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable.
5376 // For specifics regarding the bug see GLIBC BUGID 261237 :
5377 // http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html.
5378 // Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future
5379 // will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar
5380 // is used. (The simple C test-case provided in the GLIBC bug report manifests the
5381 // hang). The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos()
5382 // and monitorenter when we're using 1-0 locking. All those operations may result in
5383 // calls to pthread_cond_timedwait(). Using LD_ASSUME_KERNEL to use an older version
5384 // of libpthread avoids the problem, but isn't practical.
5385 //
5386 // Possible remedies:
5387 //
5388 // 1. Establish a minimum relative wait time. 50 to 100 msecs seems to work.
5389 // This is palliative and probabilistic, however. If the thread is preempted
5390 // between the call to compute_abstime() and pthread_cond_timedwait(), more
5391 // than the minimum period may have passed, and the abstime may be stale (in the
5392 // past) resultin in a hang. Using this technique reduces the odds of a hang
5393 // but the JVM is still vulnerable, particularly on heavily loaded systems.
5394 //
5395 // 2. Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead
5396 // of the usual flag-condvar-mutex idiom. The write side of the pipe is set
5397 // NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo)
5398 // reduces to poll()+read(). This works well, but consumes 2 FDs per extant
5399 // thread.
5400 //
5401 // 3. Embargo pthread_cond_timedwait() and implement a native "chron" thread
5402 // that manages timeouts. We'd emulate pthread_cond_timedwait() by enqueuing
5403 // a timeout request to the chron thread and then blocking via pthread_cond_wait().
5404 // This also works well. In fact it avoids kernel-level scalability impediments
5405 // on certain platforms that don't handle lots of active pthread_cond_timedwait()
5406 // timers in a graceful fashion.
5407 //
5408 // 4. When the abstime value is in the past it appears that control returns
5409 // correctly from pthread_cond_timedwait(), but the condvar is left corrupt.
5410 // Subsequent timedwait/wait calls may hang indefinitely. Given that, we
5411 // can avoid the problem by reinitializing the condvar -- by cond_destroy()
5412 // followed by cond_init() -- after all calls to pthread_cond_timedwait().
5413 // It may be possible to avoid reinitialization by checking the return
5414 // value from pthread_cond_timedwait(). In addition to reinitializing the
5415 // condvar we must establish the invariant that cond_signal() is only called
5416 // within critical sections protected by the adjunct mutex. This prevents
5417 // cond_signal() from "seeing" a condvar that's in the midst of being
5418 // reinitialized or that is corrupt. Sadly, this invariant obviates the
5419 // desirable signal-after-unlock optimization that avoids futile context switching.
5420 //
5421 // I'm also concerned that some versions of NTPL might allocate an auxilliary
5422 // structure when a condvar is used or initialized. cond_destroy() would
5423 // release the helper structure. Our reinitialize-after-timedwait fix
5424 // put excessive stress on malloc/free and locks protecting the c-heap.
5425 //
5426 // We currently use (4). See the WorkAroundNTPLTimedWaitHang flag.
5427 // It may be possible to refine (4) by checking the kernel and NTPL verisons
5428 // and only enabling the work-around for vulnerable environments.
5429
5430 // utility to compute the abstime argument to timedwait:
5431 // millis is the relative timeout time
5432 // abstime will be the absolute timeout time
5433 // TODO: replace compute_abstime() with unpackTime()
5434
5435 static struct timespec* compute_abstime(timespec* abstime, jlong millis) {
5436 if (millis < 0) millis = 0;
5437
5438 jlong seconds = millis / 1000;
5439 millis %= 1000;
5440 if (seconds > 50000000) { // see man cond_timedwait(3T)
5441 seconds = 50000000;
5442 }
5443
5444 if (os::supports_monotonic_clock()) {
5445 struct timespec now;
5446 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now);
5447 assert_status(status == 0, status, "clock_gettime");
5448 abstime->tv_sec = now.tv_sec + seconds;
5449 long nanos = now.tv_nsec + millis * NANOSECS_PER_MILLISEC;
5450 if (nanos >= NANOSECS_PER_SEC) {
5451 abstime->tv_sec += 1;
5452 nanos -= NANOSECS_PER_SEC;
5453 }
5454 abstime->tv_nsec = nanos;
5455 } else {
5456 struct timeval now;
5457 int status = gettimeofday(&now, NULL);
5458 assert(status == 0, "gettimeofday");
5459 abstime->tv_sec = now.tv_sec + seconds;
5460 long usec = now.tv_usec + millis * 1000;
5461 if (usec >= 1000000) {
5462 abstime->tv_sec += 1;
5463 usec -= 1000000;
5464 }
5465 abstime->tv_nsec = usec * 1000;
5466 }
5467 return abstime;
5468 }
5469
5470 void os::PlatformEvent::park() { // AKA "down()"
5471 // Transitions for _Event:
5472 // -1 => -1 : illegal
5473 // 1 => 0 : pass - return immediately
5474 // 0 => -1 : block; then set _Event to 0 before returning
5475
5476 // Invariant: Only the thread associated with the Event/PlatformEvent
5477 // may call park().
5478 // TODO: assert that _Assoc != NULL or _Assoc == Self
5479 assert(_nParked == 0, "invariant");
5480
5481 int v;
5482 for (;;) {
5483 v = _Event;
5484 if (Atomic::cmpxchg(v-1, &_Event, v) == v) break;
5485 }
5486 guarantee(v >= 0, "invariant");
5487 if (v == 0) {
5488 // Do this the hard way by blocking ...
5489 int status = pthread_mutex_lock(_mutex);
5490 assert_status(status == 0, status, "mutex_lock");
5491 guarantee(_nParked == 0, "invariant");
5492 ++_nParked;
5493 while (_Event < 0) {
5494 status = pthread_cond_wait(_cond, _mutex);
5495 // for some reason, under 2.7 lwp_cond_wait() may return ETIME ...
5496 // Treat this the same as if the wait was interrupted
5497 if (status == ETIME) { status = EINTR; }
5498 assert_status(status == 0 || status == EINTR, status, "cond_wait");
5499 }
5500 --_nParked;
5501
5502 _Event = 0;
5503 status = pthread_mutex_unlock(_mutex);
5504 assert_status(status == 0, status, "mutex_unlock");
5505 // Paranoia to ensure our locked and lock-free paths interact
5506 // correctly with each other.
5507 OrderAccess::fence();
5508 }
5509 guarantee(_Event >= 0, "invariant");
5510 }
5511
5512 int os::PlatformEvent::park(jlong millis) {
5513 // Transitions for _Event:
5514 // -1 => -1 : illegal
5515 // 1 => 0 : pass - return immediately
5516 // 0 => -1 : block; then set _Event to 0 before returning
5517
5518 guarantee(_nParked == 0, "invariant");
5519
5520 int v;
5521 for (;;) {
5522 v = _Event;
5523 if (Atomic::cmpxchg(v-1, &_Event, v) == v) break;
5524 }
5525 guarantee(v >= 0, "invariant");
5526 if (v != 0) return OS_OK;
5527
5528 // We do this the hard way, by blocking the thread.
5529 // Consider enforcing a minimum timeout value.
5530 struct timespec abst;
5531 compute_abstime(&abst, millis);
5532
5533 int ret = OS_TIMEOUT;
5534 int status = pthread_mutex_lock(_mutex);
5535 assert_status(status == 0, status, "mutex_lock");
5536 guarantee(_nParked == 0, "invariant");
5537 ++_nParked;
5538
5539 // Object.wait(timo) will return because of
5540 // (a) notification
5541 // (b) timeout
5542 // (c) thread.interrupt
5543 //
5544 // Thread.interrupt and object.notify{All} both call Event::set.
5545 // That is, we treat thread.interrupt as a special case of notification.
5546 // We ignore spurious OS wakeups unless FilterSpuriousWakeups is false.
5547 // We assume all ETIME returns are valid.
5548 //
5549 // TODO: properly differentiate simultaneous notify+interrupt.
5550 // In that case, we should propagate the notify to another waiter.
5551
5552 while (_Event < 0) {
5553 status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst);
5554 if (status != 0 && WorkAroundNPTLTimedWaitHang) {
5555 pthread_cond_destroy(_cond);
5556 pthread_cond_init(_cond, os::Linux::condAttr());
5557 }
5558 assert_status(status == 0 || status == EINTR ||
5559 status == ETIME || status == ETIMEDOUT,
5560 status, "cond_timedwait");
5561 if (!FilterSpuriousWakeups) break; // previous semantics
5562 if (status == ETIME || status == ETIMEDOUT) break;
5563 // We consume and ignore EINTR and spurious wakeups.
5564 }
5565 --_nParked;
5566 if (_Event >= 0) {
5567 ret = OS_OK;
5568 }
5569 _Event = 0;
5570 status = pthread_mutex_unlock(_mutex);
5571 assert_status(status == 0, status, "mutex_unlock");
5572 assert(_nParked == 0, "invariant");
5573 // Paranoia to ensure our locked and lock-free paths interact
5574 // correctly with each other.
5575 OrderAccess::fence();
5576 return ret;
5577 }
5578
5579 void os::PlatformEvent::unpark() {
5580 // Transitions for _Event:
5581 // 0 => 1 : just return
5582 // 1 => 1 : just return
5583 // -1 => either 0 or 1; must signal target thread
5584 // That is, we can safely transition _Event from -1 to either
5585 // 0 or 1.
5586 // See also: "Semaphores in Plan 9" by Mullender & Cox
5587 //
5588 // Note: Forcing a transition from "-1" to "1" on an unpark() means
5589 // that it will take two back-to-back park() calls for the owning
5590 // thread to block. This has the benefit of forcing a spurious return
5591 // from the first park() call after an unpark() call which will help
5592 // shake out uses of park() and unpark() without condition variables.
5593
5594 if (Atomic::xchg(1, &_Event) >= 0) return;
5595
5596 // Wait for the thread associated with the event to vacate
5597 int status = pthread_mutex_lock(_mutex);
5598 assert_status(status == 0, status, "mutex_lock");
5599 int AnyWaiters = _nParked;
5600 assert(AnyWaiters == 0 || AnyWaiters == 1, "invariant");
5601 if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) {
5602 AnyWaiters = 0;
5603 pthread_cond_signal(_cond);
5604 }
5605 status = pthread_mutex_unlock(_mutex);
5606 assert_status(status == 0, status, "mutex_unlock");
5607 if (AnyWaiters != 0) {
5608 // Note that we signal() *after* dropping the lock for "immortal" Events.
5609 // This is safe and avoids a common class of futile wakeups. In rare
5610 // circumstances this can cause a thread to return prematurely from
5611 // cond_{timed}wait() but the spurious wakeup is benign and the victim
5612 // will simply re-test the condition and re-park itself.
5613 // This provides particular benefit if the underlying platform does not
5614 // provide wait morphing.
5615 status = pthread_cond_signal(_cond);
5616 assert_status(status == 0, status, "cond_signal");
5617 }
5618 }
5619
5620
5621 // JSR166
5622 // -------------------------------------------------------
5623
5624 // The solaris and linux implementations of park/unpark are fairly
5625 // conservative for now, but can be improved. They currently use a
5626 // mutex/condvar pair, plus a a count.
5627 // Park decrements count if > 0, else does a condvar wait. Unpark
5628 // sets count to 1 and signals condvar. Only one thread ever waits
5629 // on the condvar. Contention seen when trying to park implies that someone
5630 // is unparking you, so don't wait. And spurious returns are fine, so there
5631 // is no need to track notifications.
5632
5633 // This code is common to linux and solaris and will be moved to a
5634 // common place in dolphin.
5635 //
5636 // The passed in time value is either a relative time in nanoseconds
5637 // or an absolute time in milliseconds. Either way it has to be unpacked
5638 // into suitable seconds and nanoseconds components and stored in the
5639 // given timespec structure.
5640 // Given time is a 64-bit value and the time_t used in the timespec is only
5641 // a signed-32-bit value (except on 64-bit Linux) we have to watch for
5642 // overflow if times way in the future are given. Further on Solaris versions
5643 // prior to 10 there is a restriction (see cond_timedwait) that the specified
5644 // number of seconds, in abstime, is less than current_time + 100,000,000.
5645 // As it will be 28 years before "now + 100000000" will overflow we can
5646 // ignore overflow and just impose a hard-limit on seconds using the value
5647 // of "now + 100,000,000". This places a limit on the timeout of about 3.17
5648 // years from "now".
5649
5650 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) {
5651 assert(time > 0, "convertTime");
5652 time_t max_secs = 0;
5653
5654 if (!os::supports_monotonic_clock() || isAbsolute) {
5655 struct timeval now;
5656 int status = gettimeofday(&now, NULL);
5657 assert(status == 0, "gettimeofday");
5658
5659 max_secs = now.tv_sec + MAX_SECS;
5660
5661 if (isAbsolute) {
5662 jlong secs = time / 1000;
5663 if (secs > max_secs) {
5664 absTime->tv_sec = max_secs;
5665 } else {
5666 absTime->tv_sec = secs;
5667 }
5668 absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC;
5669 } else {
5670 jlong secs = time / NANOSECS_PER_SEC;
5671 if (secs >= MAX_SECS) {
5672 absTime->tv_sec = max_secs;
5673 absTime->tv_nsec = 0;
5674 } else {
5675 absTime->tv_sec = now.tv_sec + secs;
5676 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000;
5677 if (absTime->tv_nsec >= NANOSECS_PER_SEC) {
5678 absTime->tv_nsec -= NANOSECS_PER_SEC;
5679 ++absTime->tv_sec; // note: this must be <= max_secs
5680 }
5681 }
5682 }
5683 } else {
5684 // must be relative using monotonic clock
5685 struct timespec now;
5686 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now);
5687 assert_status(status == 0, status, "clock_gettime");
5688 max_secs = now.tv_sec + MAX_SECS;
5689 jlong secs = time / NANOSECS_PER_SEC;
5690 if (secs >= MAX_SECS) {
5691 absTime->tv_sec = max_secs;
5692 absTime->tv_nsec = 0;
5693 } else {
5694 absTime->tv_sec = now.tv_sec + secs;
5695 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_nsec;
5696 if (absTime->tv_nsec >= NANOSECS_PER_SEC) {
5697 absTime->tv_nsec -= NANOSECS_PER_SEC;
5698 ++absTime->tv_sec; // note: this must be <= max_secs
5699 }
5700 }
5701 }
5702 assert(absTime->tv_sec >= 0, "tv_sec < 0");
5703 assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs");
5704 assert(absTime->tv_nsec >= 0, "tv_nsec < 0");
5705 assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec");
5706 }
5707
5708 void Parker::park(bool isAbsolute, jlong time) {
5709 // Ideally we'd do something useful while spinning, such
5710 // as calling unpackTime().
5711
5712 // Optional fast-path check:
5713 // Return immediately if a permit is available.
5714 // We depend on Atomic::xchg() having full barrier semantics
5715 // since we are doing a lock-free update to _counter.
5716 if (Atomic::xchg(0, &_counter) > 0) return;
5717
5718 Thread* thread = Thread::current();
5719 assert(thread->is_Java_thread(), "Must be JavaThread");
5720 JavaThread *jt = (JavaThread *)thread;
5721
5722 // Optional optimization -- avoid state transitions if there's an interrupt pending.
5723 // Check interrupt before trying to wait
5724 if (Thread::is_interrupted(thread, false)) {
5725 return;
5726 }
5727
5728 // Next, demultiplex/decode time arguments
5729 timespec absTime;
5730 if (time < 0 || (isAbsolute && time == 0)) { // don't wait at all
5731 return;
5732 }
5733 if (time > 0) {
5734 unpackTime(&absTime, isAbsolute, time);
5735 }
5736
5737
5738 // Enter safepoint region
5739 // Beware of deadlocks such as 6317397.
5740 // The per-thread Parker:: mutex is a classic leaf-lock.
5741 // In particular a thread must never block on the Threads_lock while
5742 // holding the Parker:: mutex. If safepoints are pending both the
5743 // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock.
5744 ThreadBlockInVM tbivm(jt);
5745
5746 // Don't wait if cannot get lock since interference arises from
5747 // unblocking. Also. check interrupt before trying wait
5748 if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) {
5749 return;
5750 }
5751
5752 int status;
5753 if (_counter > 0) { // no wait needed
5754 _counter = 0;
5755 status = pthread_mutex_unlock(_mutex);
5756 assert(status == 0, "invariant");
5757 // Paranoia to ensure our locked and lock-free paths interact
5758 // correctly with each other and Java-level accesses.
5759 OrderAccess::fence();
5760 return;
5761 }
5762
5763 #ifdef ASSERT
5764 // Don't catch signals while blocked; let the running threads have the signals.
5765 // (This allows a debugger to break into the running thread.)
5766 sigset_t oldsigs;
5767 sigset_t* allowdebug_blocked = os::Linux::allowdebug_blocked_signals();
5768 pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs);
5769 #endif
5770
5771 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */);
5772 jt->set_suspend_equivalent();
5773 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
5774
5775 assert(_cur_index == -1, "invariant");
5776 if (time == 0) {
5777 _cur_index = REL_INDEX; // arbitrary choice when not timed
5778 status = pthread_cond_wait(&_cond[_cur_index], _mutex);
5779 } else {
5780 _cur_index = isAbsolute ? ABS_INDEX : REL_INDEX;
5781 status = os::Linux::safe_cond_timedwait(&_cond[_cur_index], _mutex, &absTime);
5782 if (status != 0 && WorkAroundNPTLTimedWaitHang) {
5783 pthread_cond_destroy(&_cond[_cur_index]);
5784 pthread_cond_init(&_cond[_cur_index], isAbsolute ? NULL : os::Linux::condAttr());
5785 }
5786 }
5787 _cur_index = -1;
5788 assert_status(status == 0 || status == EINTR ||
5789 status == ETIME || status == ETIMEDOUT,
5790 status, "cond_timedwait");
5791
5792 #ifdef ASSERT
5793 pthread_sigmask(SIG_SETMASK, &oldsigs, NULL);
5794 #endif
5795
5796 _counter = 0;
5797 status = pthread_mutex_unlock(_mutex);
5798 assert_status(status == 0, status, "invariant");
5799 // Paranoia to ensure our locked and lock-free paths interact
5800 // correctly with each other and Java-level accesses.
5801 OrderAccess::fence();
5802
5803 // If externally suspended while waiting, re-suspend
5804 if (jt->handle_special_suspend_equivalent_condition()) {
5805 jt->java_suspend_self();
5806 }
5807 }
5808
5809 void Parker::unpark() {
5810 int status = pthread_mutex_lock(_mutex);
5811 assert(status == 0, "invariant");
5812 const int s = _counter;
5813 _counter = 1;
5814 if (s < 1) {
5815 // thread might be parked
5816 if (_cur_index != -1) {
5817 // thread is definitely parked
5818 if (WorkAroundNPTLTimedWaitHang) {
5819 status = pthread_cond_signal(&_cond[_cur_index]);
5820 assert(status == 0, "invariant");
5821 status = pthread_mutex_unlock(_mutex);
5822 assert(status == 0, "invariant");
5823 } else {
5824 status = pthread_mutex_unlock(_mutex);
5825 assert(status == 0, "invariant");
5826 status = pthread_cond_signal(&_cond[_cur_index]);
5827 assert(status == 0, "invariant");
5828 }
5829 } else {
5830 pthread_mutex_unlock(_mutex);
5831 assert(status == 0, "invariant");
5832 }
5833 } else {
5834 pthread_mutex_unlock(_mutex);
5835 assert(status == 0, "invariant");
5836 }
5837 }
5838
5839
5840 extern char** environ;
5841
5842 // Run the specified command in a separate process. Return its exit value,
5843 // or -1 on failure (e.g. can't fork a new process).
5844 // Unlike system(), this function can be called from signal handler. It
5845 // doesn't block SIGINT et al.
5846 int os::fork_and_exec(char* cmd) {
5847 const char * argv[4] = {"sh", "-c", cmd, NULL};
5848
5849 pid_t pid = fork();
5850
5851 if (pid < 0) {
5852 // fork failed
5853 return -1;
5854
5855 } else if (pid == 0) {
5856 // child process
5857
5858 execve("/bin/sh", (char* const*)argv, environ);
5859
5860 // execve failed
5861 _exit(-1);
5862
5863 } else {
5864 // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't
5865 // care about the actual exit code, for now.
5866
5867 int status;
5868
5869 // Wait for the child process to exit. This returns immediately if
5870 // the child has already exited. */
5871 while (waitpid(pid, &status, 0) < 0) {
5872 switch (errno) {
5873 case ECHILD: return 0;
5874 case EINTR: break;
5875 default: return -1;
5876 }
5877 }
5878
5879 if (WIFEXITED(status)) {
5880 // The child exited normally; get its exit code.
5881 return WEXITSTATUS(status);
5882 } else if (WIFSIGNALED(status)) {
5883 // The child exited because of a signal
5884 // The best value to return is 0x80 + signal number,
5885 // because that is what all Unix shells do, and because
5886 // it allows callers to distinguish between process exit and
5887 // process death by signal.
5888 return 0x80 + WTERMSIG(status);
5889 } else {
5890 // Unknown exit code; pass it through
5891 return status;
5892 }
5893 }
5894 }
5895
5896 // is_headless_jre()
5897 //
5898 // Test for the existence of xawt/libmawt.so or libawt_xawt.so
5899 // in order to report if we are running in a headless jre
5900 //
5901 // Since JDK8 xawt/libmawt.so was moved into the same directory
5902 // as libawt.so, and renamed libawt_xawt.so
5903 //
5904 bool os::is_headless_jre() {
5905 struct stat statbuf;
5906 char buf[MAXPATHLEN];
5907 char libmawtpath[MAXPATHLEN];
5908 const char *xawtstr = "/xawt/libmawt.so";
5909 const char *new_xawtstr = "/libawt_xawt.so";
5910 char *p;
5911
5912 // Get path to libjvm.so
5913 os::jvm_path(buf, sizeof(buf));
5914
5915 // Get rid of libjvm.so
5916 p = strrchr(buf, '/');
5917 if (p == NULL) {
5918 return false;
5919 } else {
5920 *p = '\0';
5921 }
5922
5923 // Get rid of client or server
5924 p = strrchr(buf, '/');
5925 if (p == NULL) {
5926 return false;
5927 } else {
5928 *p = '\0';
5929 }
5930
5931 // check xawt/libmawt.so
5932 strcpy(libmawtpath, buf);
5933 strcat(libmawtpath, xawtstr);
5934 if (::stat(libmawtpath, &statbuf) == 0) return false;
5935
5936 // check libawt_xawt.so
5937 strcpy(libmawtpath, buf);
5938 strcat(libmawtpath, new_xawtstr);
5939 if (::stat(libmawtpath, &statbuf) == 0) return false;
5940
5941 return true;
5942 }
5943
5944 // Get the default path to the core file
5945 // Returns the length of the string
5946 int os::get_core_path(char* buffer, size_t bufferSize) {
5947 /*
5948 * Max length of /proc/sys/kernel/core_pattern is 128 characters.
5949 * See https://www.kernel.org/doc/Documentation/sysctl/kernel.txt
5950 */
5951 const int core_pattern_len = 129;
5952 char core_pattern[core_pattern_len] = {0};
5953
5954 int core_pattern_file = ::open("/proc/sys/kernel/core_pattern", O_RDONLY);
5955 if (core_pattern_file != -1) {
5956 ssize_t ret = ::read(core_pattern_file, core_pattern, core_pattern_len);
5957 ::close(core_pattern_file);
5958
5959 if (ret > 0) {
5960 char *last_char = core_pattern + strlen(core_pattern) - 1;
5961
5962 if (*last_char == '\n') {
5963 *last_char = '\0';
5964 }
5965 }
5966 }
5967
5968 if (strlen(core_pattern) == 0) {
5969 return -1;
5970 }
5971
5972 char *pid_pos = strstr(core_pattern, "%p");
5973 int written;
5974
5975 if (core_pattern[0] == '/') {
5976 written = jio_snprintf(buffer, bufferSize, core_pattern);
5977 } else {
5978 char cwd[PATH_MAX];
5979
5980 const char* p = get_current_directory(cwd, PATH_MAX);
5981 if (p == NULL) {
5982 return -1;
5983 }
5984
5985 if (core_pattern[0] == '|') {
5986 written = jio_snprintf(buffer, bufferSize,
5987 "\"%s\" (or dumping to %s/core.%d)",
5988 &core_pattern[1], p, current_process_id());
5989 } else {
5990 written = jio_snprintf(buffer, bufferSize, "%s/%s", p, core_pattern);
5991 }
5992 }
5993
5994 if (written < 0) {
5995 return -1;
5996 }
5997
5998 if (((size_t)written < bufferSize) && (pid_pos == NULL) && (core_pattern[0] != '|')) {
5999 int core_uses_pid_file = ::open("/proc/sys/kernel/core_uses_pid", O_RDONLY);
6000
6001 if (core_uses_pid_file != -1) {
6002 char core_uses_pid = 0;
6003 ssize_t ret = ::read(core_uses_pid_file, &core_uses_pid, 1);
6004 ::close(core_uses_pid_file);
6005
6006 if (core_uses_pid == '1') {
6007 jio_snprintf(buffer + written, bufferSize - written,
6008 ".%d", current_process_id());
6009 }
6010 }
6011 }
6012
6013 return strlen(buffer);
6014 }
6015
6016 /////////////// Unit tests ///////////////
6017
6018 #ifndef PRODUCT
6019
6020 #define test_log(...) \
6021 do { \
6022 if (VerboseInternalVMTests) { \
6023 tty->print_cr(__VA_ARGS__); \
6024 tty->flush(); \
6025 } \
6026 } while (false)
6027
6028 class TestReserveMemorySpecial : AllStatic {
6029 public:
6030 static void small_page_write(void* addr, size_t size) {
6031 size_t page_size = os::vm_page_size();
6032
6033 char* end = (char*)addr + size;
6034 for (char* p = (char*)addr; p < end; p += page_size) {
6035 *p = 1;
6036 }
6037 }
6038
6039 static void test_reserve_memory_special_huge_tlbfs_only(size_t size) {
6040 if (!UseHugeTLBFS) {
6041 return;
6042 }
6043
6044 test_log("test_reserve_memory_special_huge_tlbfs_only(" SIZE_FORMAT ")", size);
6045
6046 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_only(size, NULL, false);
6047
6048 if (addr != NULL) {
6049 small_page_write(addr, size);
6050
6051 os::Linux::release_memory_special_huge_tlbfs(addr, size);
6052 }
6053 }
6054
6055 static void test_reserve_memory_special_huge_tlbfs_only() {
6056 if (!UseHugeTLBFS) {
6057 return;
6058 }
6059
6060 size_t lp = os::large_page_size();
6061
6062 for (size_t size = lp; size <= lp * 10; size += lp) {
6063 test_reserve_memory_special_huge_tlbfs_only(size);
6064 }
6065 }
6066
6067 static void test_reserve_memory_special_huge_tlbfs_mixed() {
6068 size_t lp = os::large_page_size();
6069 size_t ag = os::vm_allocation_granularity();
6070
6071 // sizes to test
6072 const size_t sizes[] = {
6073 lp, lp + ag, lp + lp / 2, lp * 2,
6074 lp * 2 + ag, lp * 2 - ag, lp * 2 + lp / 2,
6075 lp * 10, lp * 10 + lp / 2
6076 };
6077 const int num_sizes = sizeof(sizes) / sizeof(size_t);
6078
6079 // For each size/alignment combination, we test three scenarios:
6080 // 1) with req_addr == NULL
6081 // 2) with a non-null req_addr at which we expect to successfully allocate
6082 // 3) with a non-null req_addr which contains a pre-existing mapping, at which we
6083 // expect the allocation to either fail or to ignore req_addr
6084
6085 // Pre-allocate two areas; they shall be as large as the largest allocation
6086 // and aligned to the largest alignment we will be testing.
6087 const size_t mapping_size = sizes[num_sizes - 1] * 2;
6088 char* const mapping1 = (char*) ::mmap(NULL, mapping_size,
6089 PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE,
6090 -1, 0);
6091 assert(mapping1 != MAP_FAILED, "should work");
6092
6093 char* const mapping2 = (char*) ::mmap(NULL, mapping_size,
6094 PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE,
6095 -1, 0);
6096 assert(mapping2 != MAP_FAILED, "should work");
6097
6098 // Unmap the first mapping, but leave the second mapping intact: the first
6099 // mapping will serve as a value for a "good" req_addr (case 2). The second
6100 // mapping, still intact, as "bad" req_addr (case 3).
6101 ::munmap(mapping1, mapping_size);
6102
6103 // Case 1
6104 test_log("%s, req_addr NULL:", __FUNCTION__);
6105 test_log("size align result");
6106
6107 for (int i = 0; i < num_sizes; i++) {
6108 const size_t size = sizes[i];
6109 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) {
6110 char* p = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, NULL, false);
6111 test_log(SIZE_FORMAT_HEX " " SIZE_FORMAT_HEX " -> " PTR_FORMAT " %s",
6112 size, alignment, p, (p != NULL ? "" : "(failed)"));
6113 if (p != NULL) {
6114 assert(is_ptr_aligned(p, alignment), "must be");
6115 small_page_write(p, size);
6116 os::Linux::release_memory_special_huge_tlbfs(p, size);
6117 }
6118 }
6119 }
6120
6121 // Case 2
6122 test_log("%s, req_addr non-NULL:", __FUNCTION__);
6123 test_log("size align req_addr result");
6124
6125 for (int i = 0; i < num_sizes; i++) {
6126 const size_t size = sizes[i];
6127 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) {
6128 char* const req_addr = (char*) align_ptr_up(mapping1, alignment);
6129 char* p = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, req_addr, false);
6130 test_log(SIZE_FORMAT_HEX " " SIZE_FORMAT_HEX " " PTR_FORMAT " -> " PTR_FORMAT " %s",
6131 size, alignment, req_addr, p,
6132 ((p != NULL ? (p == req_addr ? "(exact match)" : "") : "(failed)")));
6133 if (p != NULL) {
6134 assert(p == req_addr, "must be");
6135 small_page_write(p, size);
6136 os::Linux::release_memory_special_huge_tlbfs(p, size);
6137 }
6138 }
6139 }
6140
6141 // Case 3
6142 test_log("%s, req_addr non-NULL with preexisting mapping:", __FUNCTION__);
6143 test_log("size align req_addr result");
6144
6145 for (int i = 0; i < num_sizes; i++) {
6146 const size_t size = sizes[i];
6147 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) {
6148 char* const req_addr = (char*) align_ptr_up(mapping2, alignment);
6149 char* p = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, req_addr, false);
6150 test_log(SIZE_FORMAT_HEX " " SIZE_FORMAT_HEX " " PTR_FORMAT " -> " PTR_FORMAT " %s",
6151 size, alignment, req_addr, p,
6152 ((p != NULL ? "" : "(failed)")));
6153 // as the area around req_addr contains already existing mappings, the API should always
6154 // return NULL (as per contract, it cannot return another address)
6155 assert(p == NULL, "must be");
6156 }
6157 }
6158
6159 ::munmap(mapping2, mapping_size);
6160
6161 }
6162
6163 static void test_reserve_memory_special_huge_tlbfs() {
6164 if (!UseHugeTLBFS) {
6165 return;
6166 }
6167
6168 test_reserve_memory_special_huge_tlbfs_only();
6169 test_reserve_memory_special_huge_tlbfs_mixed();
6170 }
6171
6172 static void test_reserve_memory_special_shm(size_t size, size_t alignment) {
6173 if (!UseSHM) {
6174 return;
6175 }
6176
6177 test_log("test_reserve_memory_special_shm(" SIZE_FORMAT ", " SIZE_FORMAT ")", size, alignment);
6178
6179 char* addr = os::Linux::reserve_memory_special_shm(size, alignment, NULL, false);
6180
6181 if (addr != NULL) {
6182 assert(is_ptr_aligned(addr, alignment), "Check");
6183 assert(is_ptr_aligned(addr, os::large_page_size()), "Check");
6184
6185 small_page_write(addr, size);
6186
6187 os::Linux::release_memory_special_shm(addr, size);
6188 }
6189 }
6190
6191 static void test_reserve_memory_special_shm() {
6192 size_t lp = os::large_page_size();
6193 size_t ag = os::vm_allocation_granularity();
6194
6195 for (size_t size = ag; size < lp * 3; size += ag) {
6196 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) {
6197 test_reserve_memory_special_shm(size, alignment);
6198 }
6199 }
6200 }
6201
6202 static void test() {
6203 test_reserve_memory_special_huge_tlbfs();
6204 test_reserve_memory_special_shm();
6205 }
6206 };
6207
6208 void TestReserveMemorySpecial_test() {
6209 TestReserveMemorySpecial::test();
6210 }
6211
6212 #endif