1 /*
2 * Copyright (c) 1999, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 // no precompiled headers
26 #include "classfile/classLoader.hpp"
27 #include "classfile/systemDictionary.hpp"
28 #include "classfile/vmSymbols.hpp"
29 #include "code/icBuffer.hpp"
30 #include "code/vtableStubs.hpp"
31 #include "compiler/compileBroker.hpp"
32 #include "compiler/disassembler.hpp"
33 #include "interpreter/interpreter.hpp"
34 #include "jvm_linux.h"
35 #include "memory/allocation.inline.hpp"
36 #include "memory/filemap.hpp"
37 #include "mutex_linux.inline.hpp"
38 #include "oops/oop.inline.hpp"
39 #include "os_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/vmError.hpp"
72
73 // put OS-includes here
74 # include <sys/types.h>
75 # include <sys/mman.h>
76 # include <sys/stat.h>
77 # include <sys/select.h>
78 # include <pthread.h>
79 # include <signal.h>
80 # include <errno.h>
81 # include <dlfcn.h>
82 # include <stdio.h>
83 # include <unistd.h>
84 # include <sys/resource.h>
85 # include <pthread.h>
86 # include <sys/stat.h>
87 # include <sys/time.h>
88 # include <sys/times.h>
89 # include <sys/utsname.h>
90 # include <sys/socket.h>
91 # include <sys/wait.h>
92 # include <pwd.h>
93 # include <poll.h>
94 # include <semaphore.h>
95 # include <fcntl.h>
96 # include <string.h>
97 # include <syscall.h>
98 # include <sys/sysinfo.h>
99 # include <gnu/libc-version.h>
100 # include <sys/ipc.h>
101 # include <sys/shm.h>
102 # include <link.h>
103 # include <stdint.h>
104 # include <inttypes.h>
105 # include <sys/ioctl.h>
106 # include <sys/prctl.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 Mutex* os::Linux::_createThread_lock = NULL;
134 pthread_t os::Linux::_main_thread;
135 int os::Linux::_page_size = -1;
136 const int os::Linux::_vm_default_page_size = (8 * K);
137 bool os::Linux::_is_floating_stack = false;
138 bool os::Linux::_is_NPTL = false;
139 bool os::Linux::_supports_fast_thread_cpu_time = false;
140 const char * os::Linux::_glibc_version = NULL;
141 const char * os::Linux::_libpthread_version = NULL;
142 pthread_condattr_t os::Linux::_condattr[1];
143
144 static jlong initial_time_count=0;
145
146 static int clock_tics_per_sec = 100;
147
148 // For diagnostics to print a message once. see run_periodic_checks
149 static sigset_t check_signal_done;
150 static bool check_signals = true;
151
152 static pid_t _initial_pid = 0;
153
154 // Signal number used to suspend/resume a thread
155
156 // do not use any signal number less than SIGSEGV, see 4355769
157 static int SR_signum = SIGUSR2;
158 sigset_t SR_sigset;
159
160 // Used to protect dlsym() calls
161 static pthread_mutex_t dl_mutex;
162
163 // Declarations
164 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time);
165
166 #ifdef JAVASE_EMBEDDED
167 class MemNotifyThread: public Thread {
168 friend class VMStructs;
169 public:
170 virtual void run();
171
172 private:
173 static MemNotifyThread* _memnotify_thread;
174 int _fd;
175
176 public:
177
178 // Constructor
179 MemNotifyThread(int fd);
180
181 // Tester
182 bool is_memnotify_thread() const { return true; }
183
184 // Printing
185 char* name() const { return (char*)"Linux MemNotify Thread"; }
186
187 // Returns the single instance of the MemNotifyThread
188 static MemNotifyThread* memnotify_thread() { return _memnotify_thread; }
189
190 // Create and start the single instance of MemNotifyThread
191 static void start();
192 };
193 #endif // JAVASE_EMBEDDED
194
195 // utility functions
196
197 static int SR_initialize();
198
199 julong os::available_memory() {
200 return Linux::available_memory();
201 }
202
203 julong os::Linux::available_memory() {
204 // values in struct sysinfo are "unsigned long"
205 struct sysinfo si;
206 sysinfo(&si);
207
208 return (julong)si.freeram * si.mem_unit;
209 }
210
211 julong os::physical_memory() {
212 return Linux::physical_memory();
213 }
214
215 ////////////////////////////////////////////////////////////////////////////////
216 // environment support
217
218 bool os::getenv(const char* name, char* buf, int len) {
219 const char* val = ::getenv(name);
220 if (val != NULL && strlen(val) < (size_t)len) {
221 strcpy(buf, val);
222 return true;
223 }
224 if (len > 0) buf[0] = 0; // return a null string
225 return false;
226 }
227
228
229 // Return true if user is running as root.
230
231 bool os::have_special_privileges() {
232 static bool init = false;
233 static bool privileges = false;
234 if (!init) {
235 privileges = (getuid() != geteuid()) || (getgid() != getegid());
236 init = true;
237 }
238 return privileges;
239 }
240
241
242 #ifndef SYS_gettid
243 // i386: 224, ia64: 1105, amd64: 186, sparc 143
244 #ifdef __ia64__
245 #define SYS_gettid 1105
246 #elif __i386__
247 #define SYS_gettid 224
248 #elif __amd64__
249 #define SYS_gettid 186
250 #elif __sparc__
251 #define SYS_gettid 143
252 #else
253 #error define gettid for the arch
254 #endif
255 #endif
256
257 // Cpu architecture string
258 #if defined(ZERO)
259 static char cpu_arch[] = ZERO_LIBARCH;
260 #elif defined(IA64)
261 static char cpu_arch[] = "ia64";
262 #elif defined(IA32)
263 static char cpu_arch[] = "i386";
264 #elif defined(AMD64)
265 static char cpu_arch[] = "amd64";
266 #elif defined(ARM)
267 static char cpu_arch[] = "arm";
268 #elif defined(PPC32)
269 static char cpu_arch[] = "ppc";
270 #elif defined(PPC64)
271 static char cpu_arch[] = "ppc64";
272 #elif defined(SPARC)
273 #ifdef _LP64
274 static char cpu_arch[] = "sparcv9";
275 #else
276 static char cpu_arch[] = "sparc";
277 #endif
278 #else
279 #error Add appropriate cpu_arch setting
280 #endif
281
282
283 // pid_t gettid()
284 //
285 // Returns the kernel thread id of the currently running thread. Kernel
286 // thread id is used to access /proc.
287 //
288 // (Note that getpid() on LinuxThreads returns kernel thread id too; but
289 // on NPTL, it returns the same pid for all threads, as required by POSIX.)
290 //
291 pid_t os::Linux::gettid() {
292 int rslt = syscall(SYS_gettid);
293 if (rslt == -1) {
294 // old kernel, no NPTL support
295 return getpid();
296 } else {
297 return (pid_t)rslt;
298 }
299 }
300
301 // Most versions of linux have a bug where the number of processors are
302 // determined by looking at the /proc file system. In a chroot environment,
303 // the system call returns 1. This causes the VM to act as if it is
304 // a single processor and elide locking (see is_MP() call).
305 static bool unsafe_chroot_detected = false;
306 static const char *unstable_chroot_error = "/proc file system not found.\n"
307 "Java may be unstable running multithreaded in a chroot "
308 "environment on Linux when /proc filesystem is not mounted.";
309
310 void os::Linux::initialize_system_info() {
311 set_processor_count(sysconf(_SC_NPROCESSORS_CONF));
312 if (processor_count() == 1) {
313 pid_t pid = os::Linux::gettid();
314 char fname[32];
315 jio_snprintf(fname, sizeof(fname), "/proc/%d", pid);
316 FILE *fp = fopen(fname, "r");
317 if (fp == NULL) {
318 unsafe_chroot_detected = true;
319 } else {
320 fclose(fp);
321 }
322 }
323 _physical_memory = (julong)sysconf(_SC_PHYS_PAGES) * (julong)sysconf(_SC_PAGESIZE);
324 assert(processor_count() > 0, "linux error");
325 }
326
327 void os::init_system_properties_values() {
328 // The next steps are taken in the product version:
329 //
330 // Obtain the JAVA_HOME value from the location of libjvm.so.
331 // This library should be located at:
332 // <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm.so.
333 //
334 // If "/jre/lib/" appears at the right place in the path, then we
335 // assume libjvm.so is installed in a JDK and we use this path.
336 //
337 // Otherwise exit with message: "Could not create the Java virtual machine."
338 //
339 // The following extra steps are taken in the debugging version:
340 //
341 // If "/jre/lib/" does NOT appear at the right place in the path
342 // instead of exit check for $JAVA_HOME environment variable.
343 //
344 // If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>,
345 // then we append a fake suffix "hotspot/libjvm.so" to this path so
346 // it looks like libjvm.so is installed there
347 // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm.so.
348 //
349 // Otherwise exit.
350 //
351 // Important note: if the location of libjvm.so changes this
352 // code needs to be changed accordingly.
353
354 // See ld(1):
355 // The linker uses the following search paths to locate required
356 // shared libraries:
357 // 1: ...
358 // ...
359 // 7: The default directories, normally /lib and /usr/lib.
360 #if defined(AMD64) || defined(_LP64) && (defined(SPARC) || defined(PPC) || defined(S390))
361 #define DEFAULT_LIBPATH "/usr/lib64:/lib64:/lib:/usr/lib"
362 #else
363 #define DEFAULT_LIBPATH "/lib:/usr/lib"
364 #endif
365
366 // Base path of extensions installed on the system.
367 #define SYS_EXT_DIR "/usr/java/packages"
368 #define EXTENSIONS_DIR "/lib/ext"
369 #define ENDORSED_DIR "/lib/endorsed"
370
371 // Buffer that fits several sprintfs.
372 // Note that the space for the colon and the trailing null are provided
373 // by the nulls included by the sizeof operator.
374 const size_t bufsize =
375 MAX3((size_t)MAXPATHLEN, // For dll_dir & friends.
376 (size_t)MAXPATHLEN + sizeof(EXTENSIONS_DIR) + sizeof(SYS_EXT_DIR) + sizeof(EXTENSIONS_DIR), // extensions dir
377 (size_t)MAXPATHLEN + sizeof(ENDORSED_DIR)); // endorsed dir
378 char *buf = (char *)NEW_C_HEAP_ARRAY(char, bufsize, mtInternal);
379
380 // sysclasspath, java_home, dll_dir
381 {
382 char *pslash;
383 os::jvm_path(buf, bufsize);
384
385 // Found the full path to libjvm.so.
386 // Now cut the path to <java_home>/jre if we can.
387 *(strrchr(buf, '/')) = '\0'; // Get rid of /libjvm.so.
388 pslash = strrchr(buf, '/');
389 if (pslash != NULL) {
390 *pslash = '\0'; // Get rid of /{client|server|hotspot}.
391 }
392 Arguments::set_dll_dir(buf);
393
394 if (pslash != NULL) {
395 pslash = strrchr(buf, '/');
396 if (pslash != NULL) {
397 *pslash = '\0'; // Get rid of /<arch>.
398 pslash = strrchr(buf, '/');
399 if (pslash != NULL) {
400 *pslash = '\0'; // Get rid of /lib.
401 }
402 }
403 }
404 Arguments::set_java_home(buf);
405 set_boot_path('/', ':');
406 }
407
408 // Where to look for native libraries.
409 //
410 // Note: Due to a legacy implementation, most of the library path
411 // is set in the launcher. This was to accomodate linking restrictions
412 // on legacy Linux implementations (which are no longer supported).
413 // Eventually, all the library path setting will be done here.
414 //
415 // However, to prevent the proliferation of improperly built native
416 // libraries, the new path component /usr/java/packages is added here.
417 // Eventually, all the library path setting will be done here.
418 {
419 // Get the user setting of LD_LIBRARY_PATH, and prepended it. It
420 // should always exist (until the legacy problem cited above is
421 // addressed).
422 const char *v = ::getenv("LD_LIBRARY_PATH");
423 const char *v_colon = ":";
424 if (v == NULL) { v = ""; v_colon = ""; }
425 // That's +1 for the colon and +1 for the trailing '\0'.
426 char *ld_library_path = (char *)NEW_C_HEAP_ARRAY(char,
427 strlen(v) + 1 +
428 sizeof(SYS_EXT_DIR) + sizeof("/lib/") + strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH) + 1,
429 mtInternal);
430 sprintf(ld_library_path, "%s%s" SYS_EXT_DIR "/lib/%s:" DEFAULT_LIBPATH, v, v_colon, cpu_arch);
431 Arguments::set_library_path(ld_library_path);
432 FREE_C_HEAP_ARRAY(char, ld_library_path, mtInternal);
433 }
434
435 // Extensions directories.
436 sprintf(buf, "%s" EXTENSIONS_DIR ":" SYS_EXT_DIR EXTENSIONS_DIR, Arguments::get_java_home());
437 Arguments::set_ext_dirs(buf);
438
439 // Endorsed standards default directory.
440 sprintf(buf, "%s" ENDORSED_DIR, Arguments::get_java_home());
441 Arguments::set_endorsed_dirs(buf);
442
443 FREE_C_HEAP_ARRAY(char, buf, mtInternal);
444
445 #undef DEFAULT_LIBPATH
446 #undef SYS_EXT_DIR
447 #undef EXTENSIONS_DIR
448 #undef ENDORSED_DIR
449 }
450
451 ////////////////////////////////////////////////////////////////////////////////
452 // breakpoint support
453
454 void os::breakpoint() {
455 BREAKPOINT;
456 }
457
458 extern "C" void breakpoint() {
459 // use debugger to set breakpoint here
460 }
461
462 ////////////////////////////////////////////////////////////////////////////////
463 // signal support
464
465 debug_only(static bool signal_sets_initialized = false);
466 static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs;
467
468 bool os::Linux::is_sig_ignored(int sig) {
469 struct sigaction oact;
470 sigaction(sig, (struct sigaction*)NULL, &oact);
471 void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*, oact.sa_sigaction)
472 : CAST_FROM_FN_PTR(void*, oact.sa_handler);
473 if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN)) {
474 return true;
475 } else {
476 return false;
477 }
478 }
479
480 void os::Linux::signal_sets_init() {
481 // Should also have an assertion stating we are still single-threaded.
482 assert(!signal_sets_initialized, "Already initialized");
483 // Fill in signals that are necessarily unblocked for all threads in
484 // the VM. Currently, we unblock the following signals:
485 // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden
486 // by -Xrs (=ReduceSignalUsage));
487 // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all
488 // other threads. The "ReduceSignalUsage" boolean tells us not to alter
489 // the dispositions or masks wrt these signals.
490 // Programs embedding the VM that want to use the above signals for their
491 // own purposes must, at this time, use the "-Xrs" option to prevent
492 // interference with shutdown hooks and BREAK_SIGNAL thread dumping.
493 // (See bug 4345157, and other related bugs).
494 // In reality, though, unblocking these signals is really a nop, since
495 // these signals are not blocked by default.
496 sigemptyset(&unblocked_sigs);
497 sigemptyset(&allowdebug_blocked_sigs);
498 sigaddset(&unblocked_sigs, SIGILL);
499 sigaddset(&unblocked_sigs, SIGSEGV);
500 sigaddset(&unblocked_sigs, SIGBUS);
501 sigaddset(&unblocked_sigs, SIGFPE);
502 #if defined(PPC64)
503 sigaddset(&unblocked_sigs, SIGTRAP);
504 #endif
505 sigaddset(&unblocked_sigs, SR_signum);
506
507 if (!ReduceSignalUsage) {
508 if (!os::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) {
509 sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL);
510 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL);
511 }
512 if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) {
513 sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL);
514 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL);
515 }
516 if (!os::Linux::is_sig_ignored(SHUTDOWN3_SIGNAL)) {
517 sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL);
518 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN3_SIGNAL);
519 }
520 }
521 // Fill in signals that are blocked by all but the VM thread.
522 sigemptyset(&vm_sigs);
523 if (!ReduceSignalUsage) {
524 sigaddset(&vm_sigs, BREAK_SIGNAL);
525 }
526 debug_only(signal_sets_initialized = true);
527
528 }
529
530 // These are signals that are unblocked while a thread is running Java.
531 // (For some reason, they get blocked by default.)
532 sigset_t* os::Linux::unblocked_signals() {
533 assert(signal_sets_initialized, "Not initialized");
534 return &unblocked_sigs;
535 }
536
537 // These are the signals that are blocked while a (non-VM) thread is
538 // running Java. Only the VM thread handles these signals.
539 sigset_t* os::Linux::vm_signals() {
540 assert(signal_sets_initialized, "Not initialized");
541 return &vm_sigs;
542 }
543
544 // These are signals that are blocked during cond_wait to allow debugger in
545 sigset_t* os::Linux::allowdebug_blocked_signals() {
546 assert(signal_sets_initialized, "Not initialized");
547 return &allowdebug_blocked_sigs;
548 }
549
550 void os::Linux::hotspot_sigmask(Thread* thread) {
551
552 //Save caller's signal mask before setting VM signal mask
553 sigset_t caller_sigmask;
554 pthread_sigmask(SIG_BLOCK, NULL, &caller_sigmask);
555
556 OSThread* osthread = thread->osthread();
557 osthread->set_caller_sigmask(caller_sigmask);
558
559 pthread_sigmask(SIG_UNBLOCK, os::Linux::unblocked_signals(), NULL);
560
561 if (!ReduceSignalUsage) {
562 if (thread->is_VM_thread()) {
563 // Only the VM thread handles BREAK_SIGNAL ...
564 pthread_sigmask(SIG_UNBLOCK, vm_signals(), NULL);
565 } else {
566 // ... all other threads block BREAK_SIGNAL
567 pthread_sigmask(SIG_BLOCK, vm_signals(), NULL);
568 }
569 }
570 }
571
572 //////////////////////////////////////////////////////////////////////////////
573 // detecting pthread library
574
575 void os::Linux::libpthread_init() {
576 // Save glibc and pthread version strings. Note that _CS_GNU_LIBC_VERSION
577 // and _CS_GNU_LIBPTHREAD_VERSION are supported in glibc >= 2.3.2. Use a
578 // generic name for earlier versions.
579 // Define macros here so we can build HotSpot on old systems.
580 #ifndef _CS_GNU_LIBC_VERSION
581 #define _CS_GNU_LIBC_VERSION 2
582 #endif
583 #ifndef _CS_GNU_LIBPTHREAD_VERSION
584 #define _CS_GNU_LIBPTHREAD_VERSION 3
585 #endif
586
587 size_t n = confstr(_CS_GNU_LIBC_VERSION, NULL, 0);
588 if (n > 0) {
589 char *str = (char *)malloc(n, mtInternal);
590 confstr(_CS_GNU_LIBC_VERSION, str, n);
591 os::Linux::set_glibc_version(str);
592 } else {
593 // _CS_GNU_LIBC_VERSION is not supported, try gnu_get_libc_version()
594 static char _gnu_libc_version[32];
595 jio_snprintf(_gnu_libc_version, sizeof(_gnu_libc_version),
596 "glibc %s %s", gnu_get_libc_version(), gnu_get_libc_release());
597 os::Linux::set_glibc_version(_gnu_libc_version);
598 }
599
600 n = confstr(_CS_GNU_LIBPTHREAD_VERSION, NULL, 0);
601 if (n > 0) {
602 char *str = (char *)malloc(n, mtInternal);
603 confstr(_CS_GNU_LIBPTHREAD_VERSION, str, n);
604 // Vanilla RH-9 (glibc 2.3.2) has a bug that confstr() always tells
605 // us "NPTL-0.29" even we are running with LinuxThreads. Check if this
606 // is the case. LinuxThreads has a hard limit on max number of threads.
607 // So sysconf(_SC_THREAD_THREADS_MAX) will return a positive value.
608 // On the other hand, NPTL does not have such a limit, sysconf()
609 // will return -1 and errno is not changed. Check if it is really NPTL.
610 if (strcmp(os::Linux::glibc_version(), "glibc 2.3.2") == 0 &&
611 strstr(str, "NPTL") &&
612 sysconf(_SC_THREAD_THREADS_MAX) > 0) {
613 free(str);
614 os::Linux::set_libpthread_version("linuxthreads");
615 } else {
616 os::Linux::set_libpthread_version(str);
617 }
618 } else {
619 // glibc before 2.3.2 only has LinuxThreads.
620 os::Linux::set_libpthread_version("linuxthreads");
621 }
622
623 if (strstr(libpthread_version(), "NPTL")) {
624 os::Linux::set_is_NPTL();
625 } else {
626 os::Linux::set_is_LinuxThreads();
627 }
628
629 // LinuxThreads have two flavors: floating-stack mode, which allows variable
630 // stack size; and fixed-stack mode. NPTL is always floating-stack.
631 if (os::Linux::is_NPTL() || os::Linux::supports_variable_stack_size()) {
632 os::Linux::set_is_floating_stack();
633 }
634 }
635
636 /////////////////////////////////////////////////////////////////////////////
637 // thread stack
638
639 // Force Linux kernel to expand current thread stack. If "bottom" is close
640 // to the stack guard, caller should block all signals.
641 //
642 // MAP_GROWSDOWN:
643 // A special mmap() flag that is used to implement thread stacks. It tells
644 // kernel that the memory region should extend downwards when needed. This
645 // allows early versions of LinuxThreads to only mmap the first few pages
646 // when creating a new thread. Linux kernel will automatically expand thread
647 // stack as needed (on page faults).
648 //
649 // However, because the memory region of a MAP_GROWSDOWN stack can grow on
650 // demand, if a page fault happens outside an already mapped MAP_GROWSDOWN
651 // region, it's hard to tell if the fault is due to a legitimate stack
652 // access or because of reading/writing non-exist memory (e.g. buffer
653 // overrun). As a rule, if the fault happens below current stack pointer,
654 // Linux kernel does not expand stack, instead a SIGSEGV is sent to the
655 // application (see Linux kernel fault.c).
656 //
657 // This Linux feature can cause SIGSEGV when VM bangs thread stack for
658 // stack overflow detection.
659 //
660 // Newer version of LinuxThreads (since glibc-2.2, or, RH-7.x) and NPTL do
661 // not use this flag. However, the stack of initial thread is not created
662 // by pthread, it is still MAP_GROWSDOWN. Also it's possible (though
663 // unlikely) that user code can create a thread with MAP_GROWSDOWN stack
664 // and then attach the thread to JVM.
665 //
666 // To get around the problem and allow stack banging on Linux, we need to
667 // manually expand thread stack after receiving the SIGSEGV.
668 //
669 // There are two ways to expand thread stack to address "bottom", we used
670 // both of them in JVM before 1.5:
671 // 1. adjust stack pointer first so that it is below "bottom", and then
672 // touch "bottom"
673 // 2. mmap() the page in question
674 //
675 // Now alternate signal stack is gone, it's harder to use 2. For instance,
676 // if current sp is already near the lower end of page 101, and we need to
677 // call mmap() to map page 100, it is possible that part of the mmap() frame
678 // will be placed in page 100. When page 100 is mapped, it is zero-filled.
679 // That will destroy the mmap() frame and cause VM to crash.
680 //
681 // The following code works by adjusting sp first, then accessing the "bottom"
682 // page to force a page fault. Linux kernel will then automatically expand the
683 // stack mapping.
684 //
685 // _expand_stack_to() assumes its frame size is less than page size, which
686 // should always be true if the function is not inlined.
687
688 #if __GNUC__ < 3 // gcc 2.x does not support noinline attribute
689 #define NOINLINE
690 #else
691 #define NOINLINE __attribute__ ((noinline))
692 #endif
693
694 static void _expand_stack_to(address bottom) NOINLINE;
695
696 static void _expand_stack_to(address bottom) {
697 address sp;
698 size_t size;
699 volatile char *p;
700
701 // Adjust bottom to point to the largest address within the same page, it
702 // gives us a one-page buffer if alloca() allocates slightly more memory.
703 bottom = (address)align_size_down((uintptr_t)bottom, os::Linux::page_size());
704 bottom += os::Linux::page_size() - 1;
705
706 // sp might be slightly above current stack pointer; if that's the case, we
707 // will alloca() a little more space than necessary, which is OK. Don't use
708 // os::current_stack_pointer(), as its result can be slightly below current
709 // stack pointer, causing us to not alloca enough to reach "bottom".
710 sp = (address)&sp;
711
712 if (sp > bottom) {
713 size = sp - bottom;
714 p = (volatile char *)alloca(size);
715 assert(p != NULL && p <= (volatile char *)bottom, "alloca problem?");
716 p[0] = '\0';
717 }
718 }
719
720 bool os::Linux::manually_expand_stack(JavaThread * t, address addr) {
721 assert(t!=NULL, "just checking");
722 assert(t->osthread()->expanding_stack(), "expand should be set");
723 assert(t->stack_base() != NULL, "stack_base was not initialized");
724
725 if (addr < t->stack_base() && addr >= t->stack_yellow_zone_base()) {
726 sigset_t mask_all, old_sigset;
727 sigfillset(&mask_all);
728 pthread_sigmask(SIG_SETMASK, &mask_all, &old_sigset);
729 _expand_stack_to(addr);
730 pthread_sigmask(SIG_SETMASK, &old_sigset, NULL);
731 return true;
732 }
733 return false;
734 }
735
736 //////////////////////////////////////////////////////////////////////////////
737 // create new thread
738
739 static address highest_vm_reserved_address();
740
741 // check if it's safe to start a new thread
742 static bool _thread_safety_check(Thread* thread) {
743 if (os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack()) {
744 // Fixed stack LinuxThreads (SuSE Linux/x86, and some versions of Redhat)
745 // Heap is mmap'ed at lower end of memory space. Thread stacks are
746 // allocated (MAP_FIXED) from high address space. Every thread stack
747 // occupies a fixed size slot (usually 2Mbytes, but user can change
748 // it to other values if they rebuild LinuxThreads).
749 //
750 // Problem with MAP_FIXED is that mmap() can still succeed even part of
751 // the memory region has already been mmap'ed. That means if we have too
752 // many threads and/or very large heap, eventually thread stack will
753 // collide with heap.
754 //
755 // Here we try to prevent heap/stack collision by comparing current
756 // stack bottom with the highest address that has been mmap'ed by JVM
757 // plus a safety margin for memory maps created by native code.
758 //
759 // This feature can be disabled by setting ThreadSafetyMargin to 0
760 //
761 if (ThreadSafetyMargin > 0) {
762 address stack_bottom = os::current_stack_base() - os::current_stack_size();
763
764 // not safe if our stack extends below the safety margin
765 return stack_bottom - ThreadSafetyMargin >= highest_vm_reserved_address();
766 } else {
767 return true;
768 }
769 } else {
770 // Floating stack LinuxThreads or NPTL:
771 // Unlike fixed stack LinuxThreads, thread stacks are not MAP_FIXED. When
772 // there's not enough space left, pthread_create() will fail. If we come
773 // here, that means enough space has been reserved for stack.
774 return true;
775 }
776 }
777
778 // Thread start routine for all newly created threads
779 static void *java_start(Thread *thread) {
780 // Try to randomize the cache line index of hot stack frames.
781 // This helps when threads of the same stack traces evict each other's
782 // cache lines. The threads can be either from the same JVM instance, or
783 // from different JVM instances. The benefit is especially true for
784 // processors with hyperthreading technology.
785 static int counter = 0;
786 int pid = os::current_process_id();
787 alloca(((pid ^ counter++) & 7) * 128);
788
789 ThreadLocalStorage::set_thread(thread);
790
791 OSThread* osthread = thread->osthread();
792 Monitor* sync = osthread->startThread_lock();
793
794 // non floating stack LinuxThreads needs extra check, see above
795 if (!_thread_safety_check(thread)) {
796 // notify parent thread
797 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
798 osthread->set_state(ZOMBIE);
799 sync->notify_all();
800 return NULL;
801 }
802
803 // thread_id is kernel thread id (similar to Solaris LWP id)
804 osthread->set_thread_id(os::Linux::gettid());
805
806 if (UseNUMA) {
807 int lgrp_id = os::numa_get_group_id();
808 if (lgrp_id != -1) {
809 thread->set_lgrp_id(lgrp_id);
810 }
811 }
812 // initialize signal mask for this thread
813 os::Linux::hotspot_sigmask(thread);
814
815 // initialize floating point control register
816 os::Linux::init_thread_fpu_state();
817
818 // handshaking with parent thread
819 {
820 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
821
822 // notify parent thread
823 osthread->set_state(INITIALIZED);
824 sync->notify_all();
825
826 // wait until os::start_thread()
827 while (osthread->get_state() == INITIALIZED) {
828 sync->wait(Mutex::_no_safepoint_check_flag);
829 }
830 }
831
832 // call one more level start routine
833 thread->run();
834
835 return 0;
836 }
837
838 bool os::create_thread(Thread* thread, ThreadType thr_type,
839 size_t stack_size) {
840 assert(thread->osthread() == NULL, "caller responsible");
841
842 // Allocate the OSThread object
843 OSThread* osthread = new OSThread(NULL, NULL);
844 if (osthread == NULL) {
845 return false;
846 }
847
848 // set the correct thread state
849 osthread->set_thread_type(thr_type);
850
851 // Initial state is ALLOCATED but not INITIALIZED
852 osthread->set_state(ALLOCATED);
853
854 thread->set_osthread(osthread);
855
856 // init thread attributes
857 pthread_attr_t attr;
858 pthread_attr_init(&attr);
859 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
860
861 // stack size
862 if (os::Linux::supports_variable_stack_size()) {
863 // calculate stack size if it's not specified by caller
864 if (stack_size == 0) {
865 stack_size = os::Linux::default_stack_size(thr_type);
866
867 switch (thr_type) {
868 case os::java_thread:
869 // Java threads use ThreadStackSize which default value can be
870 // changed with the flag -Xss
871 assert(JavaThread::stack_size_at_create() > 0, "this should be set");
872 stack_size = JavaThread::stack_size_at_create();
873 break;
874 case os::compiler_thread:
875 if (CompilerThreadStackSize > 0) {
876 stack_size = (size_t)(CompilerThreadStackSize * K);
877 break;
878 } // else fall through:
879 // use VMThreadStackSize if CompilerThreadStackSize is not defined
880 case os::vm_thread:
881 case os::pgc_thread:
882 case os::cgc_thread:
883 case os::watcher_thread:
884 if (VMThreadStackSize > 0) stack_size = (size_t)(VMThreadStackSize * K);
885 break;
886 }
887 }
888
889 stack_size = MAX2(stack_size, os::Linux::min_stack_allowed);
890 pthread_attr_setstacksize(&attr, stack_size);
891 } else {
892 // let pthread_create() pick the default value.
893 }
894
895 // glibc guard page
896 pthread_attr_setguardsize(&attr, os::Linux::default_guard_size(thr_type));
897
898 ThreadState state;
899
900 {
901 // Serialize thread creation if we are running with fixed stack LinuxThreads
902 bool lock = os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack();
903 if (lock) {
904 os::Linux::createThread_lock()->lock_without_safepoint_check();
905 }
906
907 pthread_t tid;
908 int ret = pthread_create(&tid, &attr, (void* (*)(void*)) java_start, thread);
909
910 pthread_attr_destroy(&attr);
911
912 if (ret != 0) {
913 if (PrintMiscellaneous && (Verbose || WizardMode)) {
914 perror("pthread_create()");
915 }
916 // Need to clean up stuff we've allocated so far
917 thread->set_osthread(NULL);
918 delete osthread;
919 if (lock) os::Linux::createThread_lock()->unlock();
920 return false;
921 }
922
923 // Store pthread info into the OSThread
924 osthread->set_pthread_id(tid);
925
926 // Wait until child thread is either initialized or aborted
927 {
928 Monitor* sync_with_child = osthread->startThread_lock();
929 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
930 while ((state = osthread->get_state()) == ALLOCATED) {
931 sync_with_child->wait(Mutex::_no_safepoint_check_flag);
932 }
933 }
934
935 if (lock) {
936 os::Linux::createThread_lock()->unlock();
937 }
938 }
939
940 // Aborted due to thread limit being reached
941 if (state == ZOMBIE) {
942 thread->set_osthread(NULL);
943 delete osthread;
944 return false;
945 }
946
947 // The thread is returned suspended (in state INITIALIZED),
948 // and is started higher up in the call chain
949 assert(state == INITIALIZED, "race condition");
950 return true;
951 }
952
953 /////////////////////////////////////////////////////////////////////////////
954 // attach existing thread
955
956 // bootstrap the main thread
957 bool os::create_main_thread(JavaThread* thread) {
958 assert(os::Linux::_main_thread == pthread_self(), "should be called inside main thread");
959 return create_attached_thread(thread);
960 }
961
962 bool os::create_attached_thread(JavaThread* thread) {
963 #ifdef ASSERT
964 thread->verify_not_published();
965 #endif
966
967 // Allocate the OSThread object
968 OSThread* osthread = new OSThread(NULL, NULL);
969
970 if (osthread == NULL) {
971 return false;
972 }
973
974 // Store pthread info into the OSThread
975 osthread->set_thread_id(os::Linux::gettid());
976 osthread->set_pthread_id(::pthread_self());
977
978 // initialize floating point control register
979 os::Linux::init_thread_fpu_state();
980
981 // Initial thread state is RUNNABLE
982 osthread->set_state(RUNNABLE);
983
984 thread->set_osthread(osthread);
985
986 if (UseNUMA) {
987 int lgrp_id = os::numa_get_group_id();
988 if (lgrp_id != -1) {
989 thread->set_lgrp_id(lgrp_id);
990 }
991 }
992
993 if (os::Linux::is_initial_thread()) {
994 // If current thread is initial thread, its stack is mapped on demand,
995 // see notes about MAP_GROWSDOWN. Here we try to force kernel to map
996 // the entire stack region to avoid SEGV in stack banging.
997 // It is also useful to get around the heap-stack-gap problem on SuSE
998 // kernel (see 4821821 for details). We first expand stack to the top
999 // of yellow zone, then enable stack yellow zone (order is significant,
1000 // enabling yellow zone first will crash JVM on SuSE Linux), so there
1001 // is no gap between the last two virtual memory regions.
1002
1003 JavaThread *jt = (JavaThread *)thread;
1004 address addr = jt->stack_yellow_zone_base();
1005 assert(addr != NULL, "initialization problem?");
1006 assert(jt->stack_available(addr) > 0, "stack guard should not be enabled");
1007
1008 osthread->set_expanding_stack();
1009 os::Linux::manually_expand_stack(jt, addr);
1010 osthread->clear_expanding_stack();
1011 }
1012
1013 // initialize signal mask for this thread
1014 // and save the caller's signal mask
1015 os::Linux::hotspot_sigmask(thread);
1016
1017 return true;
1018 }
1019
1020 void os::pd_start_thread(Thread* thread) {
1021 OSThread * osthread = thread->osthread();
1022 assert(osthread->get_state() != INITIALIZED, "just checking");
1023 Monitor* sync_with_child = osthread->startThread_lock();
1024 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
1025 sync_with_child->notify();
1026 }
1027
1028 // Free Linux resources related to the OSThread
1029 void os::free_thread(OSThread* osthread) {
1030 assert(osthread != NULL, "osthread not set");
1031
1032 if (Thread::current()->osthread() == osthread) {
1033 // Restore caller's signal mask
1034 sigset_t sigmask = osthread->caller_sigmask();
1035 pthread_sigmask(SIG_SETMASK, &sigmask, NULL);
1036 }
1037
1038 delete osthread;
1039 }
1040
1041 //////////////////////////////////////////////////////////////////////////////
1042 // thread local storage
1043
1044 // Restore the thread pointer if the destructor is called. This is in case
1045 // someone from JNI code sets up a destructor with pthread_key_create to run
1046 // detachCurrentThread on thread death. Unless we restore the thread pointer we
1047 // will hang or crash. When detachCurrentThread is called the key will be set
1048 // to null and we will not be called again. If detachCurrentThread is never
1049 // called we could loop forever depending on the pthread implementation.
1050 static void restore_thread_pointer(void* p) {
1051 Thread* thread = (Thread*) p;
1052 os::thread_local_storage_at_put(ThreadLocalStorage::thread_index(), thread);
1053 }
1054
1055 int os::allocate_thread_local_storage() {
1056 pthread_key_t key;
1057 int rslt = pthread_key_create(&key, restore_thread_pointer);
1058 assert(rslt == 0, "cannot allocate thread local storage");
1059 return (int)key;
1060 }
1061
1062 // Note: This is currently not used by VM, as we don't destroy TLS key
1063 // on VM exit.
1064 void os::free_thread_local_storage(int index) {
1065 int rslt = pthread_key_delete((pthread_key_t)index);
1066 assert(rslt == 0, "invalid index");
1067 }
1068
1069 void os::thread_local_storage_at_put(int index, void* value) {
1070 int rslt = pthread_setspecific((pthread_key_t)index, value);
1071 assert(rslt == 0, "pthread_setspecific failed");
1072 }
1073
1074 extern "C" Thread* get_thread() {
1075 return ThreadLocalStorage::thread();
1076 }
1077
1078 //////////////////////////////////////////////////////////////////////////////
1079 // initial thread
1080
1081 // Check if current thread is the initial thread, similar to Solaris thr_main.
1082 bool os::Linux::is_initial_thread(void) {
1083 char dummy;
1084 // If called before init complete, thread stack bottom will be null.
1085 // Can be called if fatal error occurs before initialization.
1086 if (initial_thread_stack_bottom() == NULL) return false;
1087 assert(initial_thread_stack_bottom() != NULL &&
1088 initial_thread_stack_size() != 0,
1089 "os::init did not locate initial thread's stack region");
1090 if ((address)&dummy >= initial_thread_stack_bottom() &&
1091 (address)&dummy < initial_thread_stack_bottom() + initial_thread_stack_size()) {
1092 return true;
1093 } else {
1094 return false;
1095 }
1096 }
1097
1098 // Find the virtual memory area that contains addr
1099 static bool find_vma(address addr, address* vma_low, address* vma_high) {
1100 FILE *fp = fopen("/proc/self/maps", "r");
1101 if (fp) {
1102 address low, high;
1103 while (!feof(fp)) {
1104 if (fscanf(fp, "%p-%p", &low, &high) == 2) {
1105 if (low <= addr && addr < high) {
1106 if (vma_low) *vma_low = low;
1107 if (vma_high) *vma_high = high;
1108 fclose(fp);
1109 return true;
1110 }
1111 }
1112 for (;;) {
1113 int ch = fgetc(fp);
1114 if (ch == EOF || ch == (int)'\n') break;
1115 }
1116 }
1117 fclose(fp);
1118 }
1119 return false;
1120 }
1121
1122 // Locate initial thread stack. This special handling of initial thread stack
1123 // is needed because pthread_getattr_np() on most (all?) Linux distros returns
1124 // bogus value for initial thread.
1125 void os::Linux::capture_initial_stack(size_t max_size) {
1126 // stack size is the easy part, get it from RLIMIT_STACK
1127 size_t stack_size;
1128 struct rlimit rlim;
1129 getrlimit(RLIMIT_STACK, &rlim);
1130 stack_size = rlim.rlim_cur;
1131
1132 // 6308388: a bug in ld.so will relocate its own .data section to the
1133 // lower end of primordial stack; reduce ulimit -s value a little bit
1134 // so we won't install guard page on ld.so's data section.
1135 stack_size -= 2 * page_size();
1136
1137 // 4441425: avoid crash with "unlimited" stack size on SuSE 7.1 or Redhat
1138 // 7.1, in both cases we will get 2G in return value.
1139 // 4466587: glibc 2.2.x compiled w/o "--enable-kernel=2.4.0" (RH 7.0,
1140 // SuSE 7.2, Debian) can not handle alternate signal stack correctly
1141 // for initial thread if its stack size exceeds 6M. Cap it at 2M,
1142 // in case other parts in glibc still assumes 2M max stack size.
1143 // FIXME: alt signal stack is gone, maybe we can relax this constraint?
1144 // Problem still exists RH7.2 (IA64 anyway) but 2MB is a little small
1145 if (stack_size > 2 * K * K IA64_ONLY(*2)) {
1146 stack_size = 2 * K * K IA64_ONLY(*2);
1147 }
1148 // Try to figure out where the stack base (top) is. This is harder.
1149 //
1150 // When an application is started, glibc saves the initial stack pointer in
1151 // a global variable "__libc_stack_end", which is then used by system
1152 // libraries. __libc_stack_end should be pretty close to stack top. The
1153 // variable is available since the very early days. However, because it is
1154 // a private interface, it could disappear in the future.
1155 //
1156 // Linux kernel saves start_stack information in /proc/<pid>/stat. Similar
1157 // to __libc_stack_end, it is very close to stack top, but isn't the real
1158 // stack top. Note that /proc may not exist if VM is running as a chroot
1159 // program, so reading /proc/<pid>/stat could fail. Also the contents of
1160 // /proc/<pid>/stat could change in the future (though unlikely).
1161 //
1162 // We try __libc_stack_end first. If that doesn't work, look for
1163 // /proc/<pid>/stat. If neither of them works, we use current stack pointer
1164 // as a hint, which should work well in most cases.
1165
1166 uintptr_t stack_start;
1167
1168 // try __libc_stack_end first
1169 uintptr_t *p = (uintptr_t *)dlsym(RTLD_DEFAULT, "__libc_stack_end");
1170 if (p && *p) {
1171 stack_start = *p;
1172 } else {
1173 // see if we can get the start_stack field from /proc/self/stat
1174 FILE *fp;
1175 int pid;
1176 char state;
1177 int ppid;
1178 int pgrp;
1179 int session;
1180 int nr;
1181 int tpgrp;
1182 unsigned long flags;
1183 unsigned long minflt;
1184 unsigned long cminflt;
1185 unsigned long majflt;
1186 unsigned long cmajflt;
1187 unsigned long utime;
1188 unsigned long stime;
1189 long cutime;
1190 long cstime;
1191 long prio;
1192 long nice;
1193 long junk;
1194 long it_real;
1195 uintptr_t start;
1196 uintptr_t vsize;
1197 intptr_t rss;
1198 uintptr_t rsslim;
1199 uintptr_t scodes;
1200 uintptr_t ecode;
1201 int i;
1202
1203 // Figure what the primordial thread stack base is. Code is inspired
1204 // by email from Hans Boehm. /proc/self/stat begins with current pid,
1205 // followed by command name surrounded by parentheses, state, etc.
1206 char stat[2048];
1207 int statlen;
1208
1209 fp = fopen("/proc/self/stat", "r");
1210 if (fp) {
1211 statlen = fread(stat, 1, 2047, fp);
1212 stat[statlen] = '\0';
1213 fclose(fp);
1214
1215 // Skip pid and the command string. Note that we could be dealing with
1216 // weird command names, e.g. user could decide to rename java launcher
1217 // to "java 1.4.2 :)", then the stat file would look like
1218 // 1234 (java 1.4.2 :)) R ... ...
1219 // We don't really need to know the command string, just find the last
1220 // occurrence of ")" and then start parsing from there. See bug 4726580.
1221 char * s = strrchr(stat, ')');
1222
1223 i = 0;
1224 if (s) {
1225 // Skip blank chars
1226 do s++; while (isspace(*s));
1227
1228 #define _UFM UINTX_FORMAT
1229 #define _DFM INTX_FORMAT
1230
1231 // 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2
1232 // 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
1233 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,
1234 &state, // 3 %c
1235 &ppid, // 4 %d
1236 &pgrp, // 5 %d
1237 &session, // 6 %d
1238 &nr, // 7 %d
1239 &tpgrp, // 8 %d
1240 &flags, // 9 %lu
1241 &minflt, // 10 %lu
1242 &cminflt, // 11 %lu
1243 &majflt, // 12 %lu
1244 &cmajflt, // 13 %lu
1245 &utime, // 14 %lu
1246 &stime, // 15 %lu
1247 &cutime, // 16 %ld
1248 &cstime, // 17 %ld
1249 &prio, // 18 %ld
1250 &nice, // 19 %ld
1251 &junk, // 20 %ld
1252 &it_real, // 21 %ld
1253 &start, // 22 UINTX_FORMAT
1254 &vsize, // 23 UINTX_FORMAT
1255 &rss, // 24 INTX_FORMAT
1256 &rsslim, // 25 UINTX_FORMAT
1257 &scodes, // 26 UINTX_FORMAT
1258 &ecode, // 27 UINTX_FORMAT
1259 &stack_start); // 28 UINTX_FORMAT
1260 }
1261
1262 #undef _UFM
1263 #undef _DFM
1264
1265 if (i != 28 - 2) {
1266 assert(false, "Bad conversion from /proc/self/stat");
1267 // product mode - assume we are the initial thread, good luck in the
1268 // embedded case.
1269 warning("Can't detect initial thread stack location - bad conversion");
1270 stack_start = (uintptr_t) &rlim;
1271 }
1272 } else {
1273 // For some reason we can't open /proc/self/stat (for example, running on
1274 // FreeBSD with a Linux emulator, or inside chroot), this should work for
1275 // most cases, so don't abort:
1276 warning("Can't detect initial thread stack location - no /proc/self/stat");
1277 stack_start = (uintptr_t) &rlim;
1278 }
1279 }
1280
1281 // Now we have a pointer (stack_start) very close to the stack top, the
1282 // next thing to do is to figure out the exact location of stack top. We
1283 // can find out the virtual memory area that contains stack_start by
1284 // reading /proc/self/maps, it should be the last vma in /proc/self/maps,
1285 // and its upper limit is the real stack top. (again, this would fail if
1286 // running inside chroot, because /proc may not exist.)
1287
1288 uintptr_t stack_top;
1289 address low, high;
1290 if (find_vma((address)stack_start, &low, &high)) {
1291 // success, "high" is the true stack top. (ignore "low", because initial
1292 // thread stack grows on demand, its real bottom is high - RLIMIT_STACK.)
1293 stack_top = (uintptr_t)high;
1294 } else {
1295 // failed, likely because /proc/self/maps does not exist
1296 warning("Can't detect initial thread stack location - find_vma failed");
1297 // best effort: stack_start is normally within a few pages below the real
1298 // stack top, use it as stack top, and reduce stack size so we won't put
1299 // guard page outside stack.
1300 stack_top = stack_start;
1301 stack_size -= 16 * page_size();
1302 }
1303
1304 // stack_top could be partially down the page so align it
1305 stack_top = align_size_up(stack_top, page_size());
1306
1307 if (max_size && stack_size > max_size) {
1308 _initial_thread_stack_size = max_size;
1309 } else {
1310 _initial_thread_stack_size = stack_size;
1311 }
1312
1313 _initial_thread_stack_size = align_size_down(_initial_thread_stack_size, page_size());
1314 _initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size;
1315 }
1316
1317 ////////////////////////////////////////////////////////////////////////////////
1318 // time support
1319
1320 // Time since start-up in seconds to a fine granularity.
1321 // Used by VMSelfDestructTimer and the MemProfiler.
1322 double os::elapsedTime() {
1323
1324 return ((double)os::elapsed_counter()) / os::elapsed_frequency(); // nanosecond resolution
1325 }
1326
1327 jlong os::elapsed_counter() {
1328 return javaTimeNanos() - initial_time_count;
1329 }
1330
1331 jlong os::elapsed_frequency() {
1332 return NANOSECS_PER_SEC; // nanosecond resolution
1333 }
1334
1335 bool os::supports_vtime() { return true; }
1336 bool os::enable_vtime() { return false; }
1337 bool os::vtime_enabled() { return false; }
1338
1339 double os::elapsedVTime() {
1340 struct rusage usage;
1341 int retval = getrusage(RUSAGE_THREAD, &usage);
1342 if (retval == 0) {
1343 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);
1344 } else {
1345 // better than nothing, but not much
1346 return elapsedTime();
1347 }
1348 }
1349
1350 jlong os::javaTimeMillis() {
1351 timeval time;
1352 int status = gettimeofday(&time, NULL);
1353 assert(status != -1, "linux error");
1354 return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000);
1355 }
1356
1357 #ifndef CLOCK_MONOTONIC
1358 #define CLOCK_MONOTONIC (1)
1359 #endif
1360
1361 void os::Linux::clock_init() {
1362 // we do dlopen's in this particular order due to bug in linux
1363 // dynamical loader (see 6348968) leading to crash on exit
1364 void* handle = dlopen("librt.so.1", RTLD_LAZY);
1365 if (handle == NULL) {
1366 handle = dlopen("librt.so", RTLD_LAZY);
1367 }
1368
1369 if (handle) {
1370 int (*clock_getres_func)(clockid_t, struct timespec*) =
1371 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres");
1372 int (*clock_gettime_func)(clockid_t, struct timespec*) =
1373 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime");
1374 if (clock_getres_func && clock_gettime_func) {
1375 // See if monotonic clock is supported by the kernel. Note that some
1376 // early implementations simply return kernel jiffies (updated every
1377 // 1/100 or 1/1000 second). It would be bad to use such a low res clock
1378 // for nano time (though the monotonic property is still nice to have).
1379 // It's fixed in newer kernels, however clock_getres() still returns
1380 // 1/HZ. We check if clock_getres() works, but will ignore its reported
1381 // resolution for now. Hopefully as people move to new kernels, this
1382 // won't be a problem.
1383 struct timespec res;
1384 struct timespec tp;
1385 if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 &&
1386 clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) {
1387 // yes, monotonic clock is supported
1388 _clock_gettime = clock_gettime_func;
1389 return;
1390 } else {
1391 // close librt if there is no monotonic clock
1392 dlclose(handle);
1393 }
1394 }
1395 }
1396 warning("No monotonic clock was available - timed services may " \
1397 "be adversely affected if the time-of-day clock changes");
1398 }
1399
1400 #ifndef SYS_clock_getres
1401 #if defined(IA32) || defined(AMD64)
1402 #define SYS_clock_getres IA32_ONLY(266) AMD64_ONLY(229)
1403 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y)
1404 #else
1405 #warning "SYS_clock_getres not defined for this platform, disabling fast_thread_cpu_time"
1406 #define sys_clock_getres(x,y) -1
1407 #endif
1408 #else
1409 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y)
1410 #endif
1411
1412 void os::Linux::fast_thread_clock_init() {
1413 if (!UseLinuxPosixThreadCPUClocks) {
1414 return;
1415 }
1416 clockid_t clockid;
1417 struct timespec tp;
1418 int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) =
1419 (int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid");
1420
1421 // Switch to using fast clocks for thread cpu time if
1422 // the sys_clock_getres() returns 0 error code.
1423 // Note, that some kernels may support the current thread
1424 // clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks
1425 // returned by the pthread_getcpuclockid().
1426 // If the fast Posix clocks are supported then the sys_clock_getres()
1427 // must return at least tp.tv_sec == 0 which means a resolution
1428 // better than 1 sec. This is extra check for reliability.
1429
1430 if (pthread_getcpuclockid_func &&
1431 pthread_getcpuclockid_func(_main_thread, &clockid) == 0 &&
1432 sys_clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) {
1433 _supports_fast_thread_cpu_time = true;
1434 _pthread_getcpuclockid = pthread_getcpuclockid_func;
1435 }
1436 }
1437
1438 jlong os::javaTimeNanos() {
1439 if (os::supports_monotonic_clock()) {
1440 struct timespec tp;
1441 int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp);
1442 assert(status == 0, "gettime error");
1443 jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec);
1444 return result;
1445 } else {
1446 timeval time;
1447 int status = gettimeofday(&time, NULL);
1448 assert(status != -1, "linux error");
1449 jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec);
1450 return 1000 * usecs;
1451 }
1452 }
1453
1454 void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) {
1455 if (os::supports_monotonic_clock()) {
1456 info_ptr->max_value = ALL_64_BITS;
1457
1458 // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past
1459 info_ptr->may_skip_backward = false; // not subject to resetting or drifting
1460 info_ptr->may_skip_forward = false; // not subject to resetting or drifting
1461 } else {
1462 // gettimeofday - based on time in seconds since the Epoch thus does not wrap
1463 info_ptr->max_value = ALL_64_BITS;
1464
1465 // gettimeofday is a real time clock so it skips
1466 info_ptr->may_skip_backward = true;
1467 info_ptr->may_skip_forward = true;
1468 }
1469
1470 info_ptr->kind = JVMTI_TIMER_ELAPSED; // elapsed not CPU time
1471 }
1472
1473 // Return the real, user, and system times in seconds from an
1474 // arbitrary fixed point in the past.
1475 bool os::getTimesSecs(double* process_real_time,
1476 double* process_user_time,
1477 double* process_system_time) {
1478 struct tms ticks;
1479 clock_t real_ticks = times(&ticks);
1480
1481 if (real_ticks == (clock_t) (-1)) {
1482 return false;
1483 } else {
1484 double ticks_per_second = (double) clock_tics_per_sec;
1485 *process_user_time = ((double) ticks.tms_utime) / ticks_per_second;
1486 *process_system_time = ((double) ticks.tms_stime) / ticks_per_second;
1487 *process_real_time = ((double) real_ticks) / ticks_per_second;
1488
1489 return true;
1490 }
1491 }
1492
1493
1494 char * os::local_time_string(char *buf, size_t buflen) {
1495 struct tm t;
1496 time_t long_time;
1497 time(&long_time);
1498 localtime_r(&long_time, &t);
1499 jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d",
1500 t.tm_year + 1900, t.tm_mon + 1, t.tm_mday,
1501 t.tm_hour, t.tm_min, t.tm_sec);
1502 return buf;
1503 }
1504
1505 struct tm* os::localtime_pd(const time_t* clock, struct tm* res) {
1506 return localtime_r(clock, res);
1507 }
1508
1509 ////////////////////////////////////////////////////////////////////////////////
1510 // runtime exit support
1511
1512 // Note: os::shutdown() might be called very early during initialization, or
1513 // called from signal handler. Before adding something to os::shutdown(), make
1514 // sure it is async-safe and can handle partially initialized VM.
1515 void os::shutdown() {
1516
1517 // allow PerfMemory to attempt cleanup of any persistent resources
1518 perfMemory_exit();
1519
1520 // needs to remove object in file system
1521 AttachListener::abort();
1522
1523 // flush buffered output, finish log files
1524 ostream_abort();
1525
1526 // Check for abort hook
1527 abort_hook_t abort_hook = Arguments::abort_hook();
1528 if (abort_hook != NULL) {
1529 abort_hook();
1530 }
1531
1532 }
1533
1534 // Note: os::abort() might be called very early during initialization, or
1535 // called from signal handler. Before adding something to os::abort(), make
1536 // sure it is async-safe and can handle partially initialized VM.
1537 void os::abort(bool dump_core) {
1538 os::shutdown();
1539 if (dump_core) {
1540 #ifndef PRODUCT
1541 fdStream out(defaultStream::output_fd());
1542 out.print_raw("Current thread is ");
1543 char buf[16];
1544 jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id());
1545 out.print_raw_cr(buf);
1546 out.print_raw_cr("Dumping core ...");
1547 #endif
1548 ::abort(); // dump core
1549 }
1550
1551 ::exit(1);
1552 }
1553
1554 // Die immediately, no exit hook, no abort hook, no cleanup.
1555 void os::die() {
1556 // _exit() on LinuxThreads only kills current thread
1557 ::abort();
1558 }
1559
1560
1561 // This method is a copy of JDK's sysGetLastErrorString
1562 // from src/solaris/hpi/src/system_md.c
1563
1564 size_t os::lasterror(char *buf, size_t len) {
1565 if (errno == 0) return 0;
1566
1567 const char *s = ::strerror(errno);
1568 size_t n = ::strlen(s);
1569 if (n >= len) {
1570 n = len - 1;
1571 }
1572 ::strncpy(buf, s, n);
1573 buf[n] = '\0';
1574 return n;
1575 }
1576
1577 intx os::current_thread_id() { return (intx)pthread_self(); }
1578 int os::current_process_id() {
1579
1580 // Under the old linux thread library, linux gives each thread
1581 // its own process id. Because of this each thread will return
1582 // a different pid if this method were to return the result
1583 // of getpid(2). Linux provides no api that returns the pid
1584 // of the launcher thread for the vm. This implementation
1585 // returns a unique pid, the pid of the launcher thread
1586 // that starts the vm 'process'.
1587
1588 // Under the NPTL, getpid() returns the same pid as the
1589 // launcher thread rather than a unique pid per thread.
1590 // Use gettid() if you want the old pre NPTL behaviour.
1591
1592 // if you are looking for the result of a call to getpid() that
1593 // returns a unique pid for the calling thread, then look at the
1594 // OSThread::thread_id() method in osThread_linux.hpp file
1595
1596 return (int)(_initial_pid ? _initial_pid : getpid());
1597 }
1598
1599 // DLL functions
1600
1601 const char* os::dll_file_extension() { return ".so"; }
1602
1603 // This must be hard coded because it's the system's temporary
1604 // directory not the java application's temp directory, ala java.io.tmpdir.
1605 const char* os::get_temp_directory() { return "/tmp"; }
1606
1607 static bool file_exists(const char* filename) {
1608 struct stat statbuf;
1609 if (filename == NULL || strlen(filename) == 0) {
1610 return false;
1611 }
1612 return os::stat(filename, &statbuf) == 0;
1613 }
1614
1615 bool os::dll_build_name(char* buffer, size_t buflen,
1616 const char* pname, const char* fname) {
1617 bool retval = false;
1618 // Copied from libhpi
1619 const size_t pnamelen = pname ? strlen(pname) : 0;
1620
1621 // Return error on buffer overflow.
1622 if (pnamelen + strlen(fname) + 10 > (size_t) buflen) {
1623 return retval;
1624 }
1625
1626 if (pnamelen == 0) {
1627 snprintf(buffer, buflen, "lib%s.so", fname);
1628 retval = true;
1629 } else if (strchr(pname, *os::path_separator()) != NULL) {
1630 int n;
1631 char** pelements = split_path(pname, &n);
1632 if (pelements == NULL) {
1633 return false;
1634 }
1635 for (int i = 0; i < n; i++) {
1636 // Really shouldn't be NULL, but check can't hurt
1637 if (pelements[i] == NULL || strlen(pelements[i]) == 0) {
1638 continue; // skip the empty path values
1639 }
1640 snprintf(buffer, buflen, "%s/lib%s.so", pelements[i], fname);
1641 if (file_exists(buffer)) {
1642 retval = true;
1643 break;
1644 }
1645 }
1646 // release the storage
1647 for (int i = 0; i < n; i++) {
1648 if (pelements[i] != NULL) {
1649 FREE_C_HEAP_ARRAY(char, pelements[i], mtInternal);
1650 }
1651 }
1652 if (pelements != NULL) {
1653 FREE_C_HEAP_ARRAY(char*, pelements, mtInternal);
1654 }
1655 } else {
1656 snprintf(buffer, buflen, "%s/lib%s.so", pname, fname);
1657 retval = true;
1658 }
1659 return retval;
1660 }
1661
1662 // check if addr is inside libjvm.so
1663 bool os::address_is_in_vm(address addr) {
1664 static address libjvm_base_addr;
1665 Dl_info dlinfo;
1666
1667 if (libjvm_base_addr == NULL) {
1668 if (dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo) != 0) {
1669 libjvm_base_addr = (address)dlinfo.dli_fbase;
1670 }
1671 assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm");
1672 }
1673
1674 if (dladdr((void *)addr, &dlinfo) != 0) {
1675 if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true;
1676 }
1677
1678 return false;
1679 }
1680
1681 bool os::dll_address_to_function_name(address addr, char *buf,
1682 int buflen, int *offset) {
1683 // buf is not optional, but offset is optional
1684 assert(buf != NULL, "sanity check");
1685
1686 Dl_info dlinfo;
1687
1688 if (dladdr((void*)addr, &dlinfo) != 0) {
1689 // see if we have a matching symbol
1690 if (dlinfo.dli_saddr != NULL && dlinfo.dli_sname != NULL) {
1691 if (!Decoder::demangle(dlinfo.dli_sname, buf, buflen)) {
1692 jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname);
1693 }
1694 if (offset != NULL) *offset = addr - (address)dlinfo.dli_saddr;
1695 return true;
1696 }
1697 // no matching symbol so try for just file info
1698 if (dlinfo.dli_fname != NULL && dlinfo.dli_fbase != NULL) {
1699 if (Decoder::decode((address)(addr - (address)dlinfo.dli_fbase),
1700 buf, buflen, offset, dlinfo.dli_fname)) {
1701 return true;
1702 }
1703 }
1704 }
1705
1706 buf[0] = '\0';
1707 if (offset != NULL) *offset = -1;
1708 return false;
1709 }
1710
1711 struct _address_to_library_name {
1712 address addr; // input : memory address
1713 size_t buflen; // size of fname
1714 char* fname; // output: library name
1715 address base; // library base addr
1716 };
1717
1718 static int address_to_library_name_callback(struct dl_phdr_info *info,
1719 size_t size, void *data) {
1720 int i;
1721 bool found = false;
1722 address libbase = NULL;
1723 struct _address_to_library_name * d = (struct _address_to_library_name *)data;
1724
1725 // iterate through all loadable segments
1726 for (i = 0; i < info->dlpi_phnum; i++) {
1727 address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr);
1728 if (info->dlpi_phdr[i].p_type == PT_LOAD) {
1729 // base address of a library is the lowest address of its loaded
1730 // segments.
1731 if (libbase == NULL || libbase > segbase) {
1732 libbase = segbase;
1733 }
1734 // see if 'addr' is within current segment
1735 if (segbase <= d->addr &&
1736 d->addr < segbase + info->dlpi_phdr[i].p_memsz) {
1737 found = true;
1738 }
1739 }
1740 }
1741
1742 // dlpi_name is NULL or empty if the ELF file is executable, return 0
1743 // so dll_address_to_library_name() can fall through to use dladdr() which
1744 // can figure out executable name from argv[0].
1745 if (found && info->dlpi_name && info->dlpi_name[0]) {
1746 d->base = libbase;
1747 if (d->fname) {
1748 jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name);
1749 }
1750 return 1;
1751 }
1752 return 0;
1753 }
1754
1755 bool os::dll_address_to_library_name(address addr, char* buf,
1756 int buflen, int* offset) {
1757 // buf is not optional, but offset is optional
1758 assert(buf != NULL, "sanity check");
1759
1760 Dl_info dlinfo;
1761 struct _address_to_library_name data;
1762
1763 // There is a bug in old glibc dladdr() implementation that it could resolve
1764 // to wrong library name if the .so file has a base address != NULL. Here
1765 // we iterate through the program headers of all loaded libraries to find
1766 // out which library 'addr' really belongs to. This workaround can be
1767 // removed once the minimum requirement for glibc is moved to 2.3.x.
1768 data.addr = addr;
1769 data.fname = buf;
1770 data.buflen = buflen;
1771 data.base = NULL;
1772 int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data);
1773
1774 if (rslt) {
1775 // buf already contains library name
1776 if (offset) *offset = addr - data.base;
1777 return true;
1778 }
1779 if (dladdr((void*)addr, &dlinfo) != 0) {
1780 if (dlinfo.dli_fname != NULL) {
1781 jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname);
1782 }
1783 if (dlinfo.dli_fbase != NULL && offset != NULL) {
1784 *offset = addr - (address)dlinfo.dli_fbase;
1785 }
1786 return true;
1787 }
1788
1789 buf[0] = '\0';
1790 if (offset) *offset = -1;
1791 return false;
1792 }
1793
1794 // Loads .dll/.so and
1795 // in case of error it checks if .dll/.so was built for the
1796 // same architecture as Hotspot is running on
1797
1798
1799 // Remember the stack's state. The Linux dynamic linker will change
1800 // the stack to 'executable' at most once, so we must safepoint only once.
1801 bool os::Linux::_stack_is_executable = false;
1802
1803 // VM operation that loads a library. This is necessary if stack protection
1804 // of the Java stacks can be lost during loading the library. If we
1805 // do not stop the Java threads, they can stack overflow before the stacks
1806 // are protected again.
1807 class VM_LinuxDllLoad: public VM_Operation {
1808 private:
1809 const char *_filename;
1810 char *_ebuf;
1811 int _ebuflen;
1812 void *_lib;
1813 public:
1814 VM_LinuxDllLoad(const char *fn, char *ebuf, int ebuflen) :
1815 _filename(fn), _ebuf(ebuf), _ebuflen(ebuflen), _lib(NULL) {}
1816 VMOp_Type type() const { return VMOp_LinuxDllLoad; }
1817 void doit() {
1818 _lib = os::Linux::dll_load_in_vmthread(_filename, _ebuf, _ebuflen);
1819 os::Linux::_stack_is_executable = true;
1820 }
1821 void* loaded_library() { return _lib; }
1822 };
1823
1824 void * os::dll_load(const char *filename, char *ebuf, int ebuflen) {
1825 void * result = NULL;
1826 bool load_attempted = false;
1827
1828 // Check whether the library to load might change execution rights
1829 // of the stack. If they are changed, the protection of the stack
1830 // guard pages will be lost. We need a safepoint to fix this.
1831 //
1832 // See Linux man page execstack(8) for more info.
1833 if (os::uses_stack_guard_pages() && !os::Linux::_stack_is_executable) {
1834 ElfFile ef(filename);
1835 if (!ef.specifies_noexecstack()) {
1836 if (!is_init_completed()) {
1837 os::Linux::_stack_is_executable = true;
1838 // This is OK - No Java threads have been created yet, and hence no
1839 // stack guard pages to fix.
1840 //
1841 // This should happen only when you are building JDK7 using a very
1842 // old version of JDK6 (e.g., with JPRT) and running test_gamma.
1843 //
1844 // Dynamic loader will make all stacks executable after
1845 // this function returns, and will not do that again.
1846 assert(Threads::first() == NULL, "no Java threads should exist yet.");
1847 } else {
1848 warning("You have loaded library %s which might have disabled stack guard. "
1849 "The VM will try to fix the stack guard now.\n"
1850 "It's highly recommended that you fix the library with "
1851 "'execstack -c <libfile>', or link it with '-z noexecstack'.",
1852 filename);
1853
1854 assert(Thread::current()->is_Java_thread(), "must be Java thread");
1855 JavaThread *jt = JavaThread::current();
1856 if (jt->thread_state() != _thread_in_native) {
1857 // This happens when a compiler thread tries to load a hsdis-<arch>.so file
1858 // that requires ExecStack. Cannot enter safe point. Let's give up.
1859 warning("Unable to fix stack guard. Giving up.");
1860 } else {
1861 if (!LoadExecStackDllInVMThread) {
1862 // This is for the case where the DLL has an static
1863 // constructor function that executes JNI code. We cannot
1864 // load such DLLs in the VMThread.
1865 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen);
1866 }
1867
1868 ThreadInVMfromNative tiv(jt);
1869 debug_only(VMNativeEntryWrapper vew;)
1870
1871 VM_LinuxDllLoad op(filename, ebuf, ebuflen);
1872 VMThread::execute(&op);
1873 if (LoadExecStackDllInVMThread) {
1874 result = op.loaded_library();
1875 }
1876 load_attempted = true;
1877 }
1878 }
1879 }
1880 }
1881
1882 if (!load_attempted) {
1883 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen);
1884 }
1885
1886 if (result != NULL) {
1887 // Successful loading
1888 return result;
1889 }
1890
1891 Elf32_Ehdr elf_head;
1892 int diag_msg_max_length=ebuflen-strlen(ebuf);
1893 char* diag_msg_buf=ebuf+strlen(ebuf);
1894
1895 if (diag_msg_max_length==0) {
1896 // No more space in ebuf for additional diagnostics message
1897 return NULL;
1898 }
1899
1900
1901 int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK);
1902
1903 if (file_descriptor < 0) {
1904 // Can't open library, report dlerror() message
1905 return NULL;
1906 }
1907
1908 bool failed_to_read_elf_head=
1909 (sizeof(elf_head)!=
1910 (::read(file_descriptor, &elf_head,sizeof(elf_head))));
1911
1912 ::close(file_descriptor);
1913 if (failed_to_read_elf_head) {
1914 // file i/o error - report dlerror() msg
1915 return NULL;
1916 }
1917
1918 typedef struct {
1919 Elf32_Half code; // Actual value as defined in elf.h
1920 Elf32_Half compat_class; // Compatibility of archs at VM's sense
1921 char elf_class; // 32 or 64 bit
1922 char endianess; // MSB or LSB
1923 char* name; // String representation
1924 } arch_t;
1925
1926 #ifndef EM_486
1927 #define EM_486 6 /* Intel 80486 */
1928 #endif
1929
1930 static const arch_t arch_array[]={
1931 {EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
1932 {EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
1933 {EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"},
1934 {EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"},
1935 {EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
1936 {EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
1937 {EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"},
1938 {EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"},
1939 #if defined(VM_LITTLE_ENDIAN)
1940 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2LSB, (char*)"Power PC 64"},
1941 #else
1942 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"},
1943 #endif
1944 {EM_ARM, EM_ARM, ELFCLASS32, ELFDATA2LSB, (char*)"ARM"},
1945 {EM_S390, EM_S390, ELFCLASSNONE, ELFDATA2MSB, (char*)"IBM System/390"},
1946 {EM_ALPHA, EM_ALPHA, ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"},
1947 {EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"},
1948 {EM_MIPS, EM_MIPS, ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"},
1949 {EM_PARISC, EM_PARISC, ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"},
1950 {EM_68K, EM_68K, ELFCLASS32, ELFDATA2MSB, (char*)"M68k"}
1951 };
1952
1953 #if (defined IA32)
1954 static Elf32_Half running_arch_code=EM_386;
1955 #elif (defined AMD64)
1956 static Elf32_Half running_arch_code=EM_X86_64;
1957 #elif (defined IA64)
1958 static Elf32_Half running_arch_code=EM_IA_64;
1959 #elif (defined __sparc) && (defined _LP64)
1960 static Elf32_Half running_arch_code=EM_SPARCV9;
1961 #elif (defined __sparc) && (!defined _LP64)
1962 static Elf32_Half running_arch_code=EM_SPARC;
1963 #elif (defined __powerpc64__)
1964 static Elf32_Half running_arch_code=EM_PPC64;
1965 #elif (defined __powerpc__)
1966 static Elf32_Half running_arch_code=EM_PPC;
1967 #elif (defined ARM)
1968 static Elf32_Half running_arch_code=EM_ARM;
1969 #elif (defined S390)
1970 static Elf32_Half running_arch_code=EM_S390;
1971 #elif (defined ALPHA)
1972 static Elf32_Half running_arch_code=EM_ALPHA;
1973 #elif (defined MIPSEL)
1974 static Elf32_Half running_arch_code=EM_MIPS_RS3_LE;
1975 #elif (defined PARISC)
1976 static Elf32_Half running_arch_code=EM_PARISC;
1977 #elif (defined MIPS)
1978 static Elf32_Half running_arch_code=EM_MIPS;
1979 #elif (defined M68K)
1980 static Elf32_Half running_arch_code=EM_68K;
1981 #else
1982 #error Method os::dll_load requires that one of following is defined:\
1983 IA32, AMD64, IA64, __sparc, __powerpc__, ARM, S390, ALPHA, MIPS, MIPSEL, PARISC, M68K
1984 #endif
1985
1986 // Identify compatability class for VM's architecture and library's architecture
1987 // Obtain string descriptions for architectures
1988
1989 arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL};
1990 int running_arch_index=-1;
1991
1992 for (unsigned int i=0; i < ARRAY_SIZE(arch_array); i++) {
1993 if (running_arch_code == arch_array[i].code) {
1994 running_arch_index = i;
1995 }
1996 if (lib_arch.code == arch_array[i].code) {
1997 lib_arch.compat_class = arch_array[i].compat_class;
1998 lib_arch.name = arch_array[i].name;
1999 }
2000 }
2001
2002 assert(running_arch_index != -1,
2003 "Didn't find running architecture code (running_arch_code) in arch_array");
2004 if (running_arch_index == -1) {
2005 // Even though running architecture detection failed
2006 // we may still continue with reporting dlerror() message
2007 return NULL;
2008 }
2009
2010 if (lib_arch.endianess != arch_array[running_arch_index].endianess) {
2011 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)");
2012 return NULL;
2013 }
2014
2015 #ifndef S390
2016 if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) {
2017 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)");
2018 return NULL;
2019 }
2020 #endif // !S390
2021
2022 if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) {
2023 if (lib_arch.name!=NULL) {
2024 ::snprintf(diag_msg_buf, diag_msg_max_length-1,
2025 " (Possible cause: can't load %s-bit .so on a %s-bit platform)",
2026 lib_arch.name, arch_array[running_arch_index].name);
2027 } else {
2028 ::snprintf(diag_msg_buf, diag_msg_max_length-1,
2029 " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)",
2030 lib_arch.code,
2031 arch_array[running_arch_index].name);
2032 }
2033 }
2034
2035 return NULL;
2036 }
2037
2038 void * os::Linux::dlopen_helper(const char *filename, char *ebuf,
2039 int ebuflen) {
2040 void * result = ::dlopen(filename, RTLD_LAZY);
2041 if (result == NULL) {
2042 ::strncpy(ebuf, ::dlerror(), ebuflen - 1);
2043 ebuf[ebuflen-1] = '\0';
2044 }
2045 return result;
2046 }
2047
2048 void * os::Linux::dll_load_in_vmthread(const char *filename, char *ebuf,
2049 int ebuflen) {
2050 void * result = NULL;
2051 if (LoadExecStackDllInVMThread) {
2052 result = dlopen_helper(filename, ebuf, ebuflen);
2053 }
2054
2055 // Since 7019808, libjvm.so is linked with -noexecstack. If the VM loads a
2056 // library that requires an executable stack, or which does not have this
2057 // stack attribute set, dlopen changes the stack attribute to executable. The
2058 // read protection of the guard pages gets lost.
2059 //
2060 // Need to check _stack_is_executable again as multiple VM_LinuxDllLoad
2061 // may have been queued at the same time.
2062
2063 if (!_stack_is_executable) {
2064 JavaThread *jt = Threads::first();
2065
2066 while (jt) {
2067 if (!jt->stack_guard_zone_unused() && // Stack not yet fully initialized
2068 jt->stack_yellow_zone_enabled()) { // No pending stack overflow exceptions
2069 if (!os::guard_memory((char *) jt->stack_red_zone_base() - jt->stack_red_zone_size(),
2070 jt->stack_yellow_zone_size() + jt->stack_red_zone_size())) {
2071 warning("Attempt to reguard stack yellow zone failed.");
2072 }
2073 }
2074 jt = jt->next();
2075 }
2076 }
2077
2078 return result;
2079 }
2080
2081 // glibc-2.0 libdl is not MT safe. If you are building with any glibc,
2082 // chances are you might want to run the generated bits against glibc-2.0
2083 // libdl.so, so always use locking for any version of glibc.
2084 //
2085 void* os::dll_lookup(void* handle, const char* name) {
2086 pthread_mutex_lock(&dl_mutex);
2087 void* res = dlsym(handle, name);
2088 pthread_mutex_unlock(&dl_mutex);
2089 return res;
2090 }
2091
2092 void* os::get_default_process_handle() {
2093 return (void*)::dlopen(NULL, RTLD_LAZY);
2094 }
2095
2096 static bool _print_ascii_file(const char* filename, outputStream* st) {
2097 int fd = ::open(filename, O_RDONLY);
2098 if (fd == -1) {
2099 return false;
2100 }
2101
2102 char buf[32];
2103 int bytes;
2104 while ((bytes = ::read(fd, buf, sizeof(buf))) > 0) {
2105 st->print_raw(buf, bytes);
2106 }
2107
2108 ::close(fd);
2109
2110 return true;
2111 }
2112
2113 void os::print_dll_info(outputStream *st) {
2114 st->print_cr("Dynamic libraries:");
2115
2116 char fname[32];
2117 pid_t pid = os::Linux::gettid();
2118
2119 jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid);
2120
2121 if (!_print_ascii_file(fname, st)) {
2122 st->print("Can not get library information for pid = %d\n", pid);
2123 }
2124 }
2125
2126 int os::get_loaded_modules_info(os::LoadedModulesCallbackFunc callback, void *param) {
2127 FILE *procmapsFile = NULL;
2128
2129 // Open the procfs maps file for the current process
2130 if ((procmapsFile = fopen("/proc/self/maps", "r")) != NULL) {
2131 // Allocate PATH_MAX for file name plus a reasonable size for other fields.
2132 char line[PATH_MAX + 100];
2133
2134 // Read line by line from 'file'
2135 while (fgets(line, sizeof(line), procmapsFile) != NULL) {
2136 u8 base, top, offset, inode;
2137 char permissions[5];
2138 char device[6];
2139 char name[PATH_MAX + 1];
2140
2141 // Parse fields from line
2142 sscanf(line, "%lx-%lx %4s %lx %5s %ld %s", &base, &top, permissions, &offset, device, &inode, name);
2143
2144 // Filter by device id '00:00' so that we only get file system mapped files.
2145 if (strcmp(device, "00:00") != 0) {
2146
2147 // Call callback with the fields of interest
2148 if(callback(name, (address)base, (address)top, param)) {
2149 // Oops abort, callback aborted
2150 fclose(procmapsFile);
2151 return 1;
2152 }
2153 }
2154 }
2155 fclose(procmapsFile);
2156 }
2157 return 0;
2158 }
2159
2160 void os::print_os_info_brief(outputStream* st) {
2161 os::Linux::print_distro_info(st);
2162
2163 os::Posix::print_uname_info(st);
2164
2165 os::Linux::print_libversion_info(st);
2166
2167 }
2168
2169 void os::print_os_info(outputStream* st) {
2170 st->print("OS:");
2171
2172 os::Linux::print_distro_info(st);
2173
2174 os::Posix::print_uname_info(st);
2175
2176 // Print warning if unsafe chroot environment detected
2177 if (unsafe_chroot_detected) {
2178 st->print("WARNING!! ");
2179 st->print_cr("%s", unstable_chroot_error);
2180 }
2181
2182 os::Linux::print_libversion_info(st);
2183
2184 os::Posix::print_rlimit_info(st);
2185
2186 os::Posix::print_load_average(st);
2187
2188 os::Linux::print_full_memory_info(st);
2189 }
2190
2191 // Try to identify popular distros.
2192 // Most Linux distributions have a /etc/XXX-release file, which contains
2193 // the OS version string. Newer Linux distributions have a /etc/lsb-release
2194 // file that also contains the OS version string. Some have more than one
2195 // /etc/XXX-release file (e.g. Mandrake has both /etc/mandrake-release and
2196 // /etc/redhat-release.), so the order is important.
2197 // Any Linux that is based on Redhat (i.e. Oracle, Mandrake, Sun JDS...) have
2198 // their own specific XXX-release file as well as a redhat-release file.
2199 // Because of this the XXX-release file needs to be searched for before the
2200 // redhat-release file.
2201 // Since Red Hat has a lsb-release file that is not very descriptive the
2202 // search for redhat-release needs to be before lsb-release.
2203 // Since the lsb-release file is the new standard it needs to be searched
2204 // before the older style release files.
2205 // Searching system-release (Red Hat) and os-release (other Linuxes) are a
2206 // next to last resort. The os-release file is a new standard that contains
2207 // distribution information and the system-release file seems to be an old
2208 // standard that has been replaced by the lsb-release and os-release files.
2209 // Searching for the debian_version file is the last resort. It contains
2210 // an informative string like "6.0.6" or "wheezy/sid". Because of this
2211 // "Debian " is printed before the contents of the debian_version file.
2212 void os::Linux::print_distro_info(outputStream* st) {
2213 if (!_print_ascii_file("/etc/oracle-release", st) &&
2214 !_print_ascii_file("/etc/mandriva-release", st) &&
2215 !_print_ascii_file("/etc/mandrake-release", st) &&
2216 !_print_ascii_file("/etc/sun-release", st) &&
2217 !_print_ascii_file("/etc/redhat-release", st) &&
2218 !_print_ascii_file("/etc/lsb-release", st) &&
2219 !_print_ascii_file("/etc/SuSE-release", st) &&
2220 !_print_ascii_file("/etc/turbolinux-release", st) &&
2221 !_print_ascii_file("/etc/gentoo-release", st) &&
2222 !_print_ascii_file("/etc/ltib-release", st) &&
2223 !_print_ascii_file("/etc/angstrom-version", st) &&
2224 !_print_ascii_file("/etc/system-release", st) &&
2225 !_print_ascii_file("/etc/os-release", st)) {
2226
2227 if (file_exists("/etc/debian_version")) {
2228 st->print("Debian ");
2229 _print_ascii_file("/etc/debian_version", st);
2230 } else {
2231 st->print("Linux");
2232 }
2233 }
2234 st->cr();
2235 }
2236
2237 void os::Linux::print_libversion_info(outputStream* st) {
2238 // libc, pthread
2239 st->print("libc:");
2240 st->print("%s ", os::Linux::glibc_version());
2241 st->print("%s ", os::Linux::libpthread_version());
2242 if (os::Linux::is_LinuxThreads()) {
2243 st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed");
2244 }
2245 st->cr();
2246 }
2247
2248 void os::Linux::print_full_memory_info(outputStream* st) {
2249 st->print("\n/proc/meminfo:\n");
2250 _print_ascii_file("/proc/meminfo", st);
2251 st->cr();
2252 }
2253
2254 void os::print_memory_info(outputStream* st) {
2255
2256 st->print("Memory:");
2257 st->print(" %dk page", os::vm_page_size()>>10);
2258
2259 // values in struct sysinfo are "unsigned long"
2260 struct sysinfo si;
2261 sysinfo(&si);
2262
2263 st->print(", physical " UINT64_FORMAT "k",
2264 os::physical_memory() >> 10);
2265 st->print("(" UINT64_FORMAT "k free)",
2266 os::available_memory() >> 10);
2267 st->print(", swap " UINT64_FORMAT "k",
2268 ((jlong)si.totalswap * si.mem_unit) >> 10);
2269 st->print("(" UINT64_FORMAT "k free)",
2270 ((jlong)si.freeswap * si.mem_unit) >> 10);
2271 st->cr();
2272 }
2273
2274 void os::pd_print_cpu_info(outputStream* st) {
2275 st->print("\n/proc/cpuinfo:\n");
2276 if (!_print_ascii_file("/proc/cpuinfo", st)) {
2277 st->print(" <Not Available>");
2278 }
2279 st->cr();
2280 }
2281
2282 void os::print_siginfo(outputStream* st, void* siginfo) {
2283 const siginfo_t* si = (const siginfo_t*)siginfo;
2284
2285 os::Posix::print_siginfo_brief(st, si);
2286 #if INCLUDE_CDS
2287 if (si && (si->si_signo == SIGBUS || si->si_signo == SIGSEGV) &&
2288 UseSharedSpaces) {
2289 FileMapInfo* mapinfo = FileMapInfo::current_info();
2290 if (mapinfo->is_in_shared_space(si->si_addr)) {
2291 st->print("\n\nError accessing class data sharing archive." \
2292 " Mapped file inaccessible during execution, " \
2293 " possible disk/network problem.");
2294 }
2295 }
2296 #endif
2297 st->cr();
2298 }
2299
2300
2301 static void print_signal_handler(outputStream* st, int sig,
2302 char* buf, size_t buflen);
2303
2304 void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) {
2305 st->print_cr("Signal Handlers:");
2306 print_signal_handler(st, SIGSEGV, buf, buflen);
2307 print_signal_handler(st, SIGBUS , buf, buflen);
2308 print_signal_handler(st, SIGFPE , buf, buflen);
2309 print_signal_handler(st, SIGPIPE, buf, buflen);
2310 print_signal_handler(st, SIGXFSZ, buf, buflen);
2311 print_signal_handler(st, SIGILL , buf, buflen);
2312 print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen);
2313 print_signal_handler(st, SR_signum, buf, buflen);
2314 print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen);
2315 print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen);
2316 print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen);
2317 print_signal_handler(st, BREAK_SIGNAL, buf, buflen);
2318 #if defined(PPC64)
2319 print_signal_handler(st, SIGTRAP, buf, buflen);
2320 #endif
2321 }
2322
2323 static char saved_jvm_path[MAXPATHLEN] = {0};
2324
2325 // Find the full path to the current module, libjvm.so
2326 void os::jvm_path(char *buf, jint buflen) {
2327 // Error checking.
2328 if (buflen < MAXPATHLEN) {
2329 assert(false, "must use a large-enough buffer");
2330 buf[0] = '\0';
2331 return;
2332 }
2333 // Lazy resolve the path to current module.
2334 if (saved_jvm_path[0] != 0) {
2335 strcpy(buf, saved_jvm_path);
2336 return;
2337 }
2338
2339 char dli_fname[MAXPATHLEN];
2340 bool ret = dll_address_to_library_name(
2341 CAST_FROM_FN_PTR(address, os::jvm_path),
2342 dli_fname, sizeof(dli_fname), NULL);
2343 assert(ret, "cannot locate libjvm");
2344 char *rp = NULL;
2345 if (ret && dli_fname[0] != '\0') {
2346 rp = realpath(dli_fname, buf);
2347 }
2348 if (rp == NULL) {
2349 return;
2350 }
2351
2352 if (Arguments::sun_java_launcher_is_altjvm()) {
2353 // Support for the java launcher's '-XXaltjvm=<path>' option. Typical
2354 // value for buf is "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so".
2355 // If "/jre/lib/" appears at the right place in the string, then
2356 // assume we are installed in a JDK and we're done. Otherwise, check
2357 // for a JAVA_HOME environment variable and fix up the path so it
2358 // looks like libjvm.so is installed there (append a fake suffix
2359 // hotspot/libjvm.so).
2360 const char *p = buf + strlen(buf) - 1;
2361 for (int count = 0; p > buf && count < 5; ++count) {
2362 for (--p; p > buf && *p != '/'; --p)
2363 /* empty */ ;
2364 }
2365
2366 if (strncmp(p, "/jre/lib/", 9) != 0) {
2367 // Look for JAVA_HOME in the environment.
2368 char* java_home_var = ::getenv("JAVA_HOME");
2369 if (java_home_var != NULL && java_home_var[0] != 0) {
2370 char* jrelib_p;
2371 int len;
2372
2373 // Check the current module name "libjvm.so".
2374 p = strrchr(buf, '/');
2375 assert(strstr(p, "/libjvm") == p, "invalid library name");
2376
2377 rp = realpath(java_home_var, buf);
2378 if (rp == NULL) {
2379 return;
2380 }
2381
2382 // determine if this is a legacy image or modules image
2383 // modules image doesn't have "jre" subdirectory
2384 len = strlen(buf);
2385 assert(len < buflen, "Ran out of buffer room");
2386 jrelib_p = buf + len;
2387 snprintf(jrelib_p, buflen-len, "/jre/lib/%s", cpu_arch);
2388 if (0 != access(buf, F_OK)) {
2389 snprintf(jrelib_p, buflen-len, "/lib/%s", cpu_arch);
2390 }
2391
2392 if (0 == access(buf, F_OK)) {
2393 // Use current module name "libjvm.so"
2394 len = strlen(buf);
2395 snprintf(buf + len, buflen-len, "/hotspot/libjvm.so");
2396 } else {
2397 // Go back to path of .so
2398 rp = realpath(dli_fname, buf);
2399 if (rp == NULL) {
2400 return;
2401 }
2402 }
2403 }
2404 }
2405 }
2406
2407 strncpy(saved_jvm_path, buf, MAXPATHLEN);
2408 }
2409
2410 void os::print_jni_name_prefix_on(outputStream* st, int args_size) {
2411 // no prefix required, not even "_"
2412 }
2413
2414 void os::print_jni_name_suffix_on(outputStream* st, int args_size) {
2415 // no suffix required
2416 }
2417
2418 ////////////////////////////////////////////////////////////////////////////////
2419 // sun.misc.Signal support
2420
2421 static volatile jint sigint_count = 0;
2422
2423 static void UserHandler(int sig, void *siginfo, void *context) {
2424 // 4511530 - sem_post is serialized and handled by the manager thread. When
2425 // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We
2426 // don't want to flood the manager thread with sem_post requests.
2427 if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1) {
2428 return;
2429 }
2430
2431 // Ctrl-C is pressed during error reporting, likely because the error
2432 // handler fails to abort. Let VM die immediately.
2433 if (sig == SIGINT && is_error_reported()) {
2434 os::die();
2435 }
2436
2437 os::signal_notify(sig);
2438 }
2439
2440 void* os::user_handler() {
2441 return CAST_FROM_FN_PTR(void*, UserHandler);
2442 }
2443
2444 class Semaphore : public StackObj {
2445 public:
2446 Semaphore();
2447 ~Semaphore();
2448 void signal();
2449 void wait();
2450 bool trywait();
2451 bool timedwait(unsigned int sec, int nsec);
2452 private:
2453 sem_t _semaphore;
2454 };
2455
2456 Semaphore::Semaphore() {
2457 sem_init(&_semaphore, 0, 0);
2458 }
2459
2460 Semaphore::~Semaphore() {
2461 sem_destroy(&_semaphore);
2462 }
2463
2464 void Semaphore::signal() {
2465 sem_post(&_semaphore);
2466 }
2467
2468 void Semaphore::wait() {
2469 sem_wait(&_semaphore);
2470 }
2471
2472 bool Semaphore::trywait() {
2473 return sem_trywait(&_semaphore) == 0;
2474 }
2475
2476 bool Semaphore::timedwait(unsigned int sec, int nsec) {
2477
2478 struct timespec ts;
2479 // Semaphore's are always associated with CLOCK_REALTIME
2480 os::Linux::clock_gettime(CLOCK_REALTIME, &ts);
2481 // see unpackTime for discussion on overflow checking
2482 if (sec >= MAX_SECS) {
2483 ts.tv_sec += MAX_SECS;
2484 ts.tv_nsec = 0;
2485 } else {
2486 ts.tv_sec += sec;
2487 ts.tv_nsec += nsec;
2488 if (ts.tv_nsec >= NANOSECS_PER_SEC) {
2489 ts.tv_nsec -= NANOSECS_PER_SEC;
2490 ++ts.tv_sec; // note: this must be <= max_secs
2491 }
2492 }
2493
2494 while (1) {
2495 int result = sem_timedwait(&_semaphore, &ts);
2496 if (result == 0) {
2497 return true;
2498 } else if (errno == EINTR) {
2499 continue;
2500 } else if (errno == ETIMEDOUT) {
2501 return false;
2502 } else {
2503 return false;
2504 }
2505 }
2506 }
2507
2508 extern "C" {
2509 typedef void (*sa_handler_t)(int);
2510 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *);
2511 }
2512
2513 void* os::signal(int signal_number, void* handler) {
2514 struct sigaction sigAct, oldSigAct;
2515
2516 sigfillset(&(sigAct.sa_mask));
2517 sigAct.sa_flags = SA_RESTART|SA_SIGINFO;
2518 sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler);
2519
2520 if (sigaction(signal_number, &sigAct, &oldSigAct)) {
2521 // -1 means registration failed
2522 return (void *)-1;
2523 }
2524
2525 return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler);
2526 }
2527
2528 void os::signal_raise(int signal_number) {
2529 ::raise(signal_number);
2530 }
2531
2532 // The following code is moved from os.cpp for making this
2533 // code platform specific, which it is by its very nature.
2534
2535 // Will be modified when max signal is changed to be dynamic
2536 int os::sigexitnum_pd() {
2537 return NSIG;
2538 }
2539
2540 // a counter for each possible signal value
2541 static volatile jint pending_signals[NSIG+1] = { 0 };
2542
2543 // Linux(POSIX) specific hand shaking semaphore.
2544 static sem_t sig_sem;
2545 static Semaphore sr_semaphore;
2546
2547 void os::signal_init_pd() {
2548 // Initialize signal structures
2549 ::memset((void*)pending_signals, 0, sizeof(pending_signals));
2550
2551 // Initialize signal semaphore
2552 ::sem_init(&sig_sem, 0, 0);
2553 }
2554
2555 void os::signal_notify(int sig) {
2556 Atomic::inc(&pending_signals[sig]);
2557 ::sem_post(&sig_sem);
2558 }
2559
2560 static int check_pending_signals(bool wait) {
2561 Atomic::store(0, &sigint_count);
2562 for (;;) {
2563 for (int i = 0; i < NSIG + 1; i++) {
2564 jint n = pending_signals[i];
2565 if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) {
2566 return i;
2567 }
2568 }
2569 if (!wait) {
2570 return -1;
2571 }
2572 JavaThread *thread = JavaThread::current();
2573 ThreadBlockInVM tbivm(thread);
2574
2575 bool threadIsSuspended;
2576 do {
2577 thread->set_suspend_equivalent();
2578 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
2579 ::sem_wait(&sig_sem);
2580
2581 // were we externally suspended while we were waiting?
2582 threadIsSuspended = thread->handle_special_suspend_equivalent_condition();
2583 if (threadIsSuspended) {
2584 // The semaphore has been incremented, but while we were waiting
2585 // another thread suspended us. We don't want to continue running
2586 // while suspended because that would surprise the thread that
2587 // suspended us.
2588 ::sem_post(&sig_sem);
2589
2590 thread->java_suspend_self();
2591 }
2592 } while (threadIsSuspended);
2593 }
2594 }
2595
2596 int os::signal_lookup() {
2597 return check_pending_signals(false);
2598 }
2599
2600 int os::signal_wait() {
2601 return check_pending_signals(true);
2602 }
2603
2604 ////////////////////////////////////////////////////////////////////////////////
2605 // Virtual Memory
2606
2607 int os::vm_page_size() {
2608 // Seems redundant as all get out
2609 assert(os::Linux::page_size() != -1, "must call os::init");
2610 return os::Linux::page_size();
2611 }
2612
2613 // Solaris allocates memory by pages.
2614 int os::vm_allocation_granularity() {
2615 assert(os::Linux::page_size() != -1, "must call os::init");
2616 return os::Linux::page_size();
2617 }
2618
2619 // Rationale behind this function:
2620 // current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable
2621 // mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get
2622 // samples for JITted code. Here we create private executable mapping over the code cache
2623 // and then we can use standard (well, almost, as mapping can change) way to provide
2624 // info for the reporting script by storing timestamp and location of symbol
2625 void linux_wrap_code(char* base, size_t size) {
2626 static volatile jint cnt = 0;
2627
2628 if (!UseOprofile) {
2629 return;
2630 }
2631
2632 char buf[PATH_MAX+1];
2633 int num = Atomic::add(1, &cnt);
2634
2635 snprintf(buf, sizeof(buf), "%s/hs-vm-%d-%d",
2636 os::get_temp_directory(), os::current_process_id(), num);
2637 unlink(buf);
2638
2639 int fd = ::open(buf, O_CREAT | O_RDWR, S_IRWXU);
2640
2641 if (fd != -1) {
2642 off_t rv = ::lseek(fd, size-2, SEEK_SET);
2643 if (rv != (off_t)-1) {
2644 if (::write(fd, "", 1) == 1) {
2645 mmap(base, size,
2646 PROT_READ|PROT_WRITE|PROT_EXEC,
2647 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0);
2648 }
2649 }
2650 ::close(fd);
2651 unlink(buf);
2652 }
2653 }
2654
2655 static bool recoverable_mmap_error(int err) {
2656 // See if the error is one we can let the caller handle. This
2657 // list of errno values comes from JBS-6843484. I can't find a
2658 // Linux man page that documents this specific set of errno
2659 // values so while this list currently matches Solaris, it may
2660 // change as we gain experience with this failure mode.
2661 switch (err) {
2662 case EBADF:
2663 case EINVAL:
2664 case ENOTSUP:
2665 // let the caller deal with these errors
2666 return true;
2667
2668 default:
2669 // Any remaining errors on this OS can cause our reserved mapping
2670 // to be lost. That can cause confusion where different data
2671 // structures think they have the same memory mapped. The worst
2672 // scenario is if both the VM and a library think they have the
2673 // same memory mapped.
2674 return false;
2675 }
2676 }
2677
2678 static void warn_fail_commit_memory(char* addr, size_t size, bool exec,
2679 int err) {
2680 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT
2681 ", %d) failed; error='%s' (errno=%d)", addr, size, exec,
2682 strerror(err), err);
2683 }
2684
2685 static void warn_fail_commit_memory(char* addr, size_t size,
2686 size_t alignment_hint, bool exec,
2687 int err) {
2688 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT
2689 ", " SIZE_FORMAT ", %d) failed; error='%s' (errno=%d)", addr, size,
2690 alignment_hint, exec, strerror(err), err);
2691 }
2692
2693 // NOTE: Linux kernel does not really reserve the pages for us.
2694 // All it does is to check if there are enough free pages
2695 // left at the time of mmap(). This could be a potential
2696 // problem.
2697 int os::Linux::commit_memory_impl(char* addr, size_t size, bool exec) {
2698 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
2699 uintptr_t res = (uintptr_t) ::mmap(addr, size, prot,
2700 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0);
2701 if (res != (uintptr_t) MAP_FAILED) {
2702 if (UseNUMAInterleaving) {
2703 numa_make_global(addr, size);
2704 }
2705 return 0;
2706 }
2707
2708 int err = errno; // save errno from mmap() call above
2709
2710 if (!recoverable_mmap_error(err)) {
2711 warn_fail_commit_memory(addr, size, exec, err);
2712 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, "committing reserved memory.");
2713 }
2714
2715 return err;
2716 }
2717
2718 bool os::pd_commit_memory(char* addr, size_t size, bool exec) {
2719 return os::Linux::commit_memory_impl(addr, size, exec) == 0;
2720 }
2721
2722 void os::pd_commit_memory_or_exit(char* addr, size_t size, bool exec,
2723 const char* mesg) {
2724 assert(mesg != NULL, "mesg must be specified");
2725 int err = os::Linux::commit_memory_impl(addr, size, exec);
2726 if (err != 0) {
2727 // the caller wants all commit errors to exit with the specified mesg:
2728 warn_fail_commit_memory(addr, size, exec, err);
2729 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg);
2730 }
2731 }
2732
2733 // Define MAP_HUGETLB here so we can build HotSpot on old systems.
2734 #ifndef MAP_HUGETLB
2735 #define MAP_HUGETLB 0x40000
2736 #endif
2737
2738 // Define MADV_HUGEPAGE here so we can build HotSpot on old systems.
2739 #ifndef MADV_HUGEPAGE
2740 #define MADV_HUGEPAGE 14
2741 #endif
2742
2743 int os::Linux::commit_memory_impl(char* addr, size_t size,
2744 size_t alignment_hint, bool exec) {
2745 int err = os::Linux::commit_memory_impl(addr, size, exec);
2746 if (err == 0) {
2747 realign_memory(addr, size, alignment_hint);
2748 }
2749 return err;
2750 }
2751
2752 bool os::pd_commit_memory(char* addr, size_t size, size_t alignment_hint,
2753 bool exec) {
2754 return os::Linux::commit_memory_impl(addr, size, alignment_hint, exec) == 0;
2755 }
2756
2757 void os::pd_commit_memory_or_exit(char* addr, size_t size,
2758 size_t alignment_hint, bool exec,
2759 const char* mesg) {
2760 assert(mesg != NULL, "mesg must be specified");
2761 int err = os::Linux::commit_memory_impl(addr, size, alignment_hint, exec);
2762 if (err != 0) {
2763 // the caller wants all commit errors to exit with the specified mesg:
2764 warn_fail_commit_memory(addr, size, alignment_hint, exec, err);
2765 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg);
2766 }
2767 }
2768
2769 void os::pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint) {
2770 if (UseTransparentHugePages && alignment_hint > (size_t)vm_page_size()) {
2771 // We don't check the return value: madvise(MADV_HUGEPAGE) may not
2772 // be supported or the memory may already be backed by huge pages.
2773 ::madvise(addr, bytes, MADV_HUGEPAGE);
2774 }
2775 }
2776
2777 void os::pd_free_memory(char *addr, size_t bytes, size_t alignment_hint) {
2778 // This method works by doing an mmap over an existing mmaping and effectively discarding
2779 // the existing pages. However it won't work for SHM-based large pages that cannot be
2780 // uncommitted at all. We don't do anything in this case to avoid creating a segment with
2781 // small pages on top of the SHM segment. This method always works for small pages, so we
2782 // allow that in any case.
2783 if (alignment_hint <= (size_t)os::vm_page_size() || can_commit_large_page_memory()) {
2784 commit_memory(addr, bytes, alignment_hint, !ExecMem);
2785 }
2786 }
2787
2788 void os::numa_make_global(char *addr, size_t bytes) {
2789 Linux::numa_interleave_memory(addr, bytes);
2790 }
2791
2792 // Define for numa_set_bind_policy(int). Setting the argument to 0 will set the
2793 // bind policy to MPOL_PREFERRED for the current thread.
2794 #define USE_MPOL_PREFERRED 0
2795
2796 void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) {
2797 // To make NUMA and large pages more robust when both enabled, we need to ease
2798 // the requirements on where the memory should be allocated. MPOL_BIND is the
2799 // default policy and it will force memory to be allocated on the specified
2800 // node. Changing this to MPOL_PREFERRED will prefer to allocate the memory on
2801 // the specified node, but will not force it. Using this policy will prevent
2802 // getting SIGBUS when trying to allocate large pages on NUMA nodes with no
2803 // free large pages.
2804 Linux::numa_set_bind_policy(USE_MPOL_PREFERRED);
2805 Linux::numa_tonode_memory(addr, bytes, lgrp_hint);
2806 }
2807
2808 bool os::numa_topology_changed() { return false; }
2809
2810 size_t os::numa_get_groups_num() {
2811 int max_node = Linux::numa_max_node();
2812 return max_node > 0 ? max_node + 1 : 1;
2813 }
2814
2815 int os::numa_get_group_id() {
2816 int cpu_id = Linux::sched_getcpu();
2817 if (cpu_id != -1) {
2818 int lgrp_id = Linux::get_node_by_cpu(cpu_id);
2819 if (lgrp_id != -1) {
2820 return lgrp_id;
2821 }
2822 }
2823 return 0;
2824 }
2825
2826 size_t os::numa_get_leaf_groups(int *ids, size_t size) {
2827 for (size_t i = 0; i < size; i++) {
2828 ids[i] = i;
2829 }
2830 return size;
2831 }
2832
2833 bool os::get_page_info(char *start, page_info* info) {
2834 return false;
2835 }
2836
2837 char *os::scan_pages(char *start, char* end, page_info* page_expected,
2838 page_info* page_found) {
2839 return end;
2840 }
2841
2842
2843 int os::Linux::sched_getcpu_syscall(void) {
2844 unsigned int cpu;
2845 int retval = -1;
2846
2847 #if defined(IA32)
2848 #ifndef SYS_getcpu
2849 #define SYS_getcpu 318
2850 #endif
2851 retval = syscall(SYS_getcpu, &cpu, NULL, NULL);
2852 #elif defined(AMD64)
2853 // Unfortunately we have to bring all these macros here from vsyscall.h
2854 // to be able to compile on old linuxes.
2855 #define __NR_vgetcpu 2
2856 #define VSYSCALL_START (-10UL << 20)
2857 #define VSYSCALL_SIZE 1024
2858 #define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr))
2859 typedef long (*vgetcpu_t)(unsigned int *cpu, unsigned int *node, unsigned long *tcache);
2860 vgetcpu_t vgetcpu = (vgetcpu_t)VSYSCALL_ADDR(__NR_vgetcpu);
2861 retval = vgetcpu(&cpu, NULL, NULL);
2862 #endif
2863
2864 return (retval == -1) ? retval : cpu;
2865 }
2866
2867 // Something to do with the numa-aware allocator needs these symbols
2868 extern "C" JNIEXPORT void numa_warn(int number, char *where, ...) { }
2869 extern "C" JNIEXPORT void numa_error(char *where) { }
2870 extern "C" JNIEXPORT int fork1() { return fork(); }
2871
2872
2873 // If we are running with libnuma version > 2, then we should
2874 // be trying to use symbols with versions 1.1
2875 // If we are running with earlier version, which did not have symbol versions,
2876 // we should use the base version.
2877 void* os::Linux::libnuma_dlsym(void* handle, const char *name) {
2878 void *f = dlvsym(handle, name, "libnuma_1.1");
2879 if (f == NULL) {
2880 f = dlsym(handle, name);
2881 }
2882 return f;
2883 }
2884
2885 bool os::Linux::libnuma_init() {
2886 // sched_getcpu() should be in libc.
2887 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t,
2888 dlsym(RTLD_DEFAULT, "sched_getcpu")));
2889
2890 // If it's not, try a direct syscall.
2891 if (sched_getcpu() == -1) {
2892 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t,
2893 (void*)&sched_getcpu_syscall));
2894 }
2895
2896 if (sched_getcpu() != -1) { // Does it work?
2897 void *handle = dlopen("libnuma.so.1", RTLD_LAZY);
2898 if (handle != NULL) {
2899 set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t,
2900 libnuma_dlsym(handle, "numa_node_to_cpus")));
2901 set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t,
2902 libnuma_dlsym(handle, "numa_max_node")));
2903 set_numa_available(CAST_TO_FN_PTR(numa_available_func_t,
2904 libnuma_dlsym(handle, "numa_available")));
2905 set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t,
2906 libnuma_dlsym(handle, "numa_tonode_memory")));
2907 set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t,
2908 libnuma_dlsym(handle, "numa_interleave_memory")));
2909 set_numa_set_bind_policy(CAST_TO_FN_PTR(numa_set_bind_policy_func_t,
2910 libnuma_dlsym(handle, "numa_set_bind_policy")));
2911
2912
2913 if (numa_available() != -1) {
2914 set_numa_all_nodes((unsigned long*)libnuma_dlsym(handle, "numa_all_nodes"));
2915 // Create a cpu -> node mapping
2916 _cpu_to_node = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<int>(0, true);
2917 rebuild_cpu_to_node_map();
2918 return true;
2919 }
2920 }
2921 }
2922 return false;
2923 }
2924
2925 // rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id.
2926 // The table is later used in get_node_by_cpu().
2927 void os::Linux::rebuild_cpu_to_node_map() {
2928 const size_t NCPUS = 32768; // Since the buffer size computation is very obscure
2929 // in libnuma (possible values are starting from 16,
2930 // and continuing up with every other power of 2, but less
2931 // than the maximum number of CPUs supported by kernel), and
2932 // is a subject to change (in libnuma version 2 the requirements
2933 // are more reasonable) we'll just hardcode the number they use
2934 // in the library.
2935 const size_t BitsPerCLong = sizeof(long) * CHAR_BIT;
2936
2937 size_t cpu_num = os::active_processor_count();
2938 size_t cpu_map_size = NCPUS / BitsPerCLong;
2939 size_t cpu_map_valid_size =
2940 MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size);
2941
2942 cpu_to_node()->clear();
2943 cpu_to_node()->at_grow(cpu_num - 1);
2944 size_t node_num = numa_get_groups_num();
2945
2946 unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size, mtInternal);
2947 for (size_t i = 0; i < node_num; i++) {
2948 if (numa_node_to_cpus(i, cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) {
2949 for (size_t j = 0; j < cpu_map_valid_size; j++) {
2950 if (cpu_map[j] != 0) {
2951 for (size_t k = 0; k < BitsPerCLong; k++) {
2952 if (cpu_map[j] & (1UL << k)) {
2953 cpu_to_node()->at_put(j * BitsPerCLong + k, i);
2954 }
2955 }
2956 }
2957 }
2958 }
2959 }
2960 FREE_C_HEAP_ARRAY(unsigned long, cpu_map, mtInternal);
2961 }
2962
2963 int os::Linux::get_node_by_cpu(int cpu_id) {
2964 if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) {
2965 return cpu_to_node()->at(cpu_id);
2966 }
2967 return -1;
2968 }
2969
2970 GrowableArray<int>* os::Linux::_cpu_to_node;
2971 os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu;
2972 os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus;
2973 os::Linux::numa_max_node_func_t os::Linux::_numa_max_node;
2974 os::Linux::numa_available_func_t os::Linux::_numa_available;
2975 os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory;
2976 os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory;
2977 os::Linux::numa_set_bind_policy_func_t os::Linux::_numa_set_bind_policy;
2978 unsigned long* os::Linux::_numa_all_nodes;
2979
2980 bool os::pd_uncommit_memory(char* addr, size_t size) {
2981 uintptr_t res = (uintptr_t) ::mmap(addr, size, PROT_NONE,
2982 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0);
2983 return res != (uintptr_t) MAP_FAILED;
2984 }
2985
2986 static address get_stack_commited_bottom(address bottom, size_t size) {
2987 address nbot = bottom;
2988 address ntop = bottom + size;
2989
2990 size_t page_sz = os::vm_page_size();
2991 unsigned pages = size / page_sz;
2992
2993 unsigned char vec[1];
2994 unsigned imin = 1, imax = pages + 1, imid;
2995 int mincore_return_value = 0;
2996
2997 assert(imin <= imax, "Unexpected page size");
2998
2999 while (imin < imax) {
3000 imid = (imax + imin) / 2;
3001 nbot = ntop - (imid * page_sz);
3002
3003 // Use a trick with mincore to check whether the page is mapped or not.
3004 // mincore sets vec to 1 if page resides in memory and to 0 if page
3005 // is swapped output but if page we are asking for is unmapped
3006 // it returns -1,ENOMEM
3007 mincore_return_value = mincore(nbot, page_sz, vec);
3008
3009 if (mincore_return_value == -1) {
3010 // Page is not mapped go up
3011 // to find first mapped page
3012 if (errno != EAGAIN) {
3013 assert(errno == ENOMEM, "Unexpected mincore errno");
3014 imax = imid;
3015 }
3016 } else {
3017 // Page is mapped go down
3018 // to find first not mapped page
3019 imin = imid + 1;
3020 }
3021 }
3022
3023 nbot = nbot + page_sz;
3024
3025 // Adjust stack bottom one page up if last checked page is not mapped
3026 if (mincore_return_value == -1) {
3027 nbot = nbot + page_sz;
3028 }
3029
3030 return nbot;
3031 }
3032
3033
3034 // Linux uses a growable mapping for the stack, and if the mapping for
3035 // the stack guard pages is not removed when we detach a thread the
3036 // stack cannot grow beyond the pages where the stack guard was
3037 // mapped. If at some point later in the process the stack expands to
3038 // that point, the Linux kernel cannot expand the stack any further
3039 // because the guard pages are in the way, and a segfault occurs.
3040 //
3041 // However, it's essential not to split the stack region by unmapping
3042 // a region (leaving a hole) that's already part of the stack mapping,
3043 // so if the stack mapping has already grown beyond the guard pages at
3044 // the time we create them, we have to truncate the stack mapping.
3045 // So, we need to know the extent of the stack mapping when
3046 // create_stack_guard_pages() is called.
3047
3048 // We only need this for stacks that are growable: at the time of
3049 // writing thread stacks don't use growable mappings (i.e. those
3050 // creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this
3051 // only applies to the main thread.
3052
3053 // If the (growable) stack mapping already extends beyond the point
3054 // where we're going to put our guard pages, truncate the mapping at
3055 // that point by munmap()ping it. This ensures that when we later
3056 // munmap() the guard pages we don't leave a hole in the stack
3057 // mapping. This only affects the main/initial thread
3058
3059 bool os::pd_create_stack_guard_pages(char* addr, size_t size) {
3060 if (os::Linux::is_initial_thread()) {
3061 // As we manually grow stack up to bottom inside create_attached_thread(),
3062 // it's likely that os::Linux::initial_thread_stack_bottom is mapped and
3063 // we don't need to do anything special.
3064 // Check it first, before calling heavy function.
3065 uintptr_t stack_extent = (uintptr_t) os::Linux::initial_thread_stack_bottom();
3066 unsigned char vec[1];
3067
3068 if (mincore((address)stack_extent, os::vm_page_size(), vec) == -1) {
3069 // Fallback to slow path on all errors, including EAGAIN
3070 stack_extent = (uintptr_t) get_stack_commited_bottom(
3071 os::Linux::initial_thread_stack_bottom(),
3072 (size_t)addr - stack_extent);
3073 }
3074
3075 if (stack_extent < (uintptr_t)addr) {
3076 ::munmap((void*)stack_extent, (uintptr_t)(addr - stack_extent));
3077 }
3078 }
3079
3080 return os::commit_memory(addr, size, !ExecMem);
3081 }
3082
3083 // If this is a growable mapping, remove the guard pages entirely by
3084 // munmap()ping them. If not, just call uncommit_memory(). This only
3085 // affects the main/initial thread, but guard against future OS changes
3086 // It's safe to always unmap guard pages for initial thread because we
3087 // always place it right after end of the mapped region
3088
3089 bool os::remove_stack_guard_pages(char* addr, size_t size) {
3090 uintptr_t stack_extent, stack_base;
3091
3092 if (os::Linux::is_initial_thread()) {
3093 return ::munmap(addr, size) == 0;
3094 }
3095
3096 return os::uncommit_memory(addr, size);
3097 }
3098
3099 static address _highest_vm_reserved_address = NULL;
3100
3101 // If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory
3102 // at 'requested_addr'. If there are existing memory mappings at the same
3103 // location, however, they will be overwritten. If 'fixed' is false,
3104 // 'requested_addr' is only treated as a hint, the return value may or
3105 // may not start from the requested address. Unlike Linux mmap(), this
3106 // function returns NULL to indicate failure.
3107 static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) {
3108 char * addr;
3109 int flags;
3110
3111 flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS;
3112 if (fixed) {
3113 assert((uintptr_t)requested_addr % os::Linux::page_size() == 0, "unaligned address");
3114 flags |= MAP_FIXED;
3115 }
3116
3117 // Map reserved/uncommitted pages PROT_NONE so we fail early if we
3118 // touch an uncommitted page. Otherwise, the read/write might
3119 // succeed if we have enough swap space to back the physical page.
3120 addr = (char*)::mmap(requested_addr, bytes, PROT_NONE,
3121 flags, -1, 0);
3122
3123 if (addr != MAP_FAILED) {
3124 // anon_mmap() should only get called during VM initialization,
3125 // don't need lock (actually we can skip locking even it can be called
3126 // from multiple threads, because _highest_vm_reserved_address is just a
3127 // hint about the upper limit of non-stack memory regions.)
3128 if ((address)addr + bytes > _highest_vm_reserved_address) {
3129 _highest_vm_reserved_address = (address)addr + bytes;
3130 }
3131 }
3132
3133 return addr == MAP_FAILED ? NULL : addr;
3134 }
3135
3136 // Don't update _highest_vm_reserved_address, because there might be memory
3137 // regions above addr + size. If so, releasing a memory region only creates
3138 // a hole in the address space, it doesn't help prevent heap-stack collision.
3139 //
3140 static int anon_munmap(char * addr, size_t size) {
3141 return ::munmap(addr, size) == 0;
3142 }
3143
3144 char* os::pd_reserve_memory(size_t bytes, char* requested_addr,
3145 size_t alignment_hint) {
3146 return anon_mmap(requested_addr, bytes, (requested_addr != NULL));
3147 }
3148
3149 bool os::pd_release_memory(char* addr, size_t size) {
3150 return anon_munmap(addr, size);
3151 }
3152
3153 static address highest_vm_reserved_address() {
3154 return _highest_vm_reserved_address;
3155 }
3156
3157 static bool linux_mprotect(char* addr, size_t size, int prot) {
3158 // Linux wants the mprotect address argument to be page aligned.
3159 char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::page_size());
3160
3161 // According to SUSv3, mprotect() should only be used with mappings
3162 // established by mmap(), and mmap() always maps whole pages. Unaligned
3163 // 'addr' likely indicates problem in the VM (e.g. trying to change
3164 // protection of malloc'ed or statically allocated memory). Check the
3165 // caller if you hit this assert.
3166 assert(addr == bottom, "sanity check");
3167
3168 size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Linux::page_size());
3169 return ::mprotect(bottom, size, prot) == 0;
3170 }
3171
3172 // Set protections specified
3173 bool os::protect_memory(char* addr, size_t bytes, ProtType prot,
3174 bool is_committed) {
3175 unsigned int p = 0;
3176 switch (prot) {
3177 case MEM_PROT_NONE: p = PROT_NONE; break;
3178 case MEM_PROT_READ: p = PROT_READ; break;
3179 case MEM_PROT_RW: p = PROT_READ|PROT_WRITE; break;
3180 case MEM_PROT_RWX: p = PROT_READ|PROT_WRITE|PROT_EXEC; break;
3181 default:
3182 ShouldNotReachHere();
3183 }
3184 // is_committed is unused.
3185 return linux_mprotect(addr, bytes, p);
3186 }
3187
3188 bool os::guard_memory(char* addr, size_t size) {
3189 return linux_mprotect(addr, size, PROT_NONE);
3190 }
3191
3192 bool os::unguard_memory(char* addr, size_t size) {
3193 return linux_mprotect(addr, size, PROT_READ|PROT_WRITE);
3194 }
3195
3196 bool os::Linux::transparent_huge_pages_sanity_check(bool warn,
3197 size_t page_size) {
3198 bool result = false;
3199 void *p = mmap(NULL, page_size * 2, PROT_READ|PROT_WRITE,
3200 MAP_ANONYMOUS|MAP_PRIVATE,
3201 -1, 0);
3202 if (p != MAP_FAILED) {
3203 void *aligned_p = align_ptr_up(p, page_size);
3204
3205 result = madvise(aligned_p, page_size, MADV_HUGEPAGE) == 0;
3206
3207 munmap(p, page_size * 2);
3208 }
3209
3210 if (warn && !result) {
3211 warning("TransparentHugePages is not supported by the operating system.");
3212 }
3213
3214 return result;
3215 }
3216
3217 bool os::Linux::hugetlbfs_sanity_check(bool warn, size_t page_size) {
3218 bool result = false;
3219 void *p = mmap(NULL, page_size, PROT_READ|PROT_WRITE,
3220 MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB,
3221 -1, 0);
3222
3223 if (p != MAP_FAILED) {
3224 // We don't know if this really is a huge page or not.
3225 FILE *fp = fopen("/proc/self/maps", "r");
3226 if (fp) {
3227 while (!feof(fp)) {
3228 char chars[257];
3229 long x = 0;
3230 if (fgets(chars, sizeof(chars), fp)) {
3231 if (sscanf(chars, "%lx-%*x", &x) == 1
3232 && x == (long)p) {
3233 if (strstr (chars, "hugepage")) {
3234 result = true;
3235 break;
3236 }
3237 }
3238 }
3239 }
3240 fclose(fp);
3241 }
3242 munmap(p, page_size);
3243 }
3244
3245 if (warn && !result) {
3246 warning("HugeTLBFS is not supported by the operating system.");
3247 }
3248
3249 return result;
3250 }
3251
3252 // Set the coredump_filter bits to include largepages in core dump (bit 6)
3253 //
3254 // From the coredump_filter documentation:
3255 //
3256 // - (bit 0) anonymous private memory
3257 // - (bit 1) anonymous shared memory
3258 // - (bit 2) file-backed private memory
3259 // - (bit 3) file-backed shared memory
3260 // - (bit 4) ELF header pages in file-backed private memory areas (it is
3261 // effective only if the bit 2 is cleared)
3262 // - (bit 5) hugetlb private memory
3263 // - (bit 6) hugetlb shared memory
3264 //
3265 static void set_coredump_filter(void) {
3266 FILE *f;
3267 long cdm;
3268
3269 if ((f = fopen("/proc/self/coredump_filter", "r+")) == NULL) {
3270 return;
3271 }
3272
3273 if (fscanf(f, "%lx", &cdm) != 1) {
3274 fclose(f);
3275 return;
3276 }
3277
3278 rewind(f);
3279
3280 if ((cdm & LARGEPAGES_BIT) == 0) {
3281 cdm |= LARGEPAGES_BIT;
3282 fprintf(f, "%#lx", cdm);
3283 }
3284
3285 fclose(f);
3286 }
3287
3288 // Large page support
3289
3290 static size_t _large_page_size = 0;
3291
3292 size_t os::Linux::find_large_page_size() {
3293 size_t large_page_size = 0;
3294
3295 // large_page_size on Linux is used to round up heap size. x86 uses either
3296 // 2M or 4M page, depending on whether PAE (Physical Address Extensions)
3297 // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use
3298 // page as large as 256M.
3299 //
3300 // Here we try to figure out page size by parsing /proc/meminfo and looking
3301 // for a line with the following format:
3302 // Hugepagesize: 2048 kB
3303 //
3304 // If we can't determine the value (e.g. /proc is not mounted, or the text
3305 // format has been changed), we'll use the largest page size supported by
3306 // the processor.
3307
3308 #ifndef ZERO
3309 large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M)
3310 ARM_ONLY(2 * M) PPC_ONLY(4 * M);
3311 #endif // ZERO
3312
3313 FILE *fp = fopen("/proc/meminfo", "r");
3314 if (fp) {
3315 while (!feof(fp)) {
3316 int x = 0;
3317 char buf[16];
3318 if (fscanf(fp, "Hugepagesize: %d", &x) == 1) {
3319 if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) {
3320 large_page_size = x * K;
3321 break;
3322 }
3323 } else {
3324 // skip to next line
3325 for (;;) {
3326 int ch = fgetc(fp);
3327 if (ch == EOF || ch == (int)'\n') break;
3328 }
3329 }
3330 }
3331 fclose(fp);
3332 }
3333
3334 if (!FLAG_IS_DEFAULT(LargePageSizeInBytes) && LargePageSizeInBytes != large_page_size) {
3335 warning("Setting LargePageSizeInBytes has no effect on this OS. Large page size is "
3336 SIZE_FORMAT "%s.", byte_size_in_proper_unit(large_page_size),
3337 proper_unit_for_byte_size(large_page_size));
3338 }
3339
3340 return large_page_size;
3341 }
3342
3343 size_t os::Linux::setup_large_page_size() {
3344 _large_page_size = Linux::find_large_page_size();
3345 const size_t default_page_size = (size_t)Linux::page_size();
3346 if (_large_page_size > default_page_size) {
3347 _page_sizes[0] = _large_page_size;
3348 _page_sizes[1] = default_page_size;
3349 _page_sizes[2] = 0;
3350 }
3351
3352 return _large_page_size;
3353 }
3354
3355 bool os::Linux::setup_large_page_type(size_t page_size) {
3356 if (FLAG_IS_DEFAULT(UseHugeTLBFS) &&
3357 FLAG_IS_DEFAULT(UseSHM) &&
3358 FLAG_IS_DEFAULT(UseTransparentHugePages)) {
3359
3360 // The type of large pages has not been specified by the user.
3361
3362 // Try UseHugeTLBFS and then UseSHM.
3363 UseHugeTLBFS = UseSHM = true;
3364
3365 // Don't try UseTransparentHugePages since there are known
3366 // performance issues with it turned on. This might change in the future.
3367 UseTransparentHugePages = false;
3368 }
3369
3370 if (UseTransparentHugePages) {
3371 bool warn_on_failure = !FLAG_IS_DEFAULT(UseTransparentHugePages);
3372 if (transparent_huge_pages_sanity_check(warn_on_failure, page_size)) {
3373 UseHugeTLBFS = false;
3374 UseSHM = false;
3375 return true;
3376 }
3377 UseTransparentHugePages = false;
3378 }
3379
3380 if (UseHugeTLBFS) {
3381 bool warn_on_failure = !FLAG_IS_DEFAULT(UseHugeTLBFS);
3382 if (hugetlbfs_sanity_check(warn_on_failure, page_size)) {
3383 UseSHM = false;
3384 return true;
3385 }
3386 UseHugeTLBFS = false;
3387 }
3388
3389 return UseSHM;
3390 }
3391
3392 void os::large_page_init() {
3393 if (!UseLargePages &&
3394 !UseTransparentHugePages &&
3395 !UseHugeTLBFS &&
3396 !UseSHM) {
3397 // Not using large pages.
3398 return;
3399 }
3400
3401 if (!FLAG_IS_DEFAULT(UseLargePages) && !UseLargePages) {
3402 // The user explicitly turned off large pages.
3403 // Ignore the rest of the large pages flags.
3404 UseTransparentHugePages = false;
3405 UseHugeTLBFS = false;
3406 UseSHM = false;
3407 return;
3408 }
3409
3410 size_t large_page_size = Linux::setup_large_page_size();
3411 UseLargePages = Linux::setup_large_page_type(large_page_size);
3412
3413 set_coredump_filter();
3414 }
3415
3416 #ifndef SHM_HUGETLB
3417 #define SHM_HUGETLB 04000
3418 #endif
3419
3420 char* os::Linux::reserve_memory_special_shm(size_t bytes, size_t alignment,
3421 char* req_addr, bool exec) {
3422 // "exec" is passed in but not used. Creating the shared image for
3423 // the code cache doesn't have an SHM_X executable permission to check.
3424 assert(UseLargePages && UseSHM, "only for SHM large pages");
3425 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address");
3426
3427 if (!is_size_aligned(bytes, os::large_page_size()) || alignment > os::large_page_size()) {
3428 return NULL; // Fallback to small pages.
3429 }
3430
3431 key_t key = IPC_PRIVATE;
3432 char *addr;
3433
3434 bool warn_on_failure = UseLargePages &&
3435 (!FLAG_IS_DEFAULT(UseLargePages) ||
3436 !FLAG_IS_DEFAULT(UseSHM) ||
3437 !FLAG_IS_DEFAULT(LargePageSizeInBytes));
3438 char msg[128];
3439
3440 // Create a large shared memory region to attach to based on size.
3441 // Currently, size is the total size of the heap
3442 int shmid = shmget(key, bytes, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W);
3443 if (shmid == -1) {
3444 // Possible reasons for shmget failure:
3445 // 1. shmmax is too small for Java heap.
3446 // > check shmmax value: cat /proc/sys/kernel/shmmax
3447 // > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax
3448 // 2. not enough large page memory.
3449 // > check available large pages: cat /proc/meminfo
3450 // > increase amount of large pages:
3451 // echo new_value > /proc/sys/vm/nr_hugepages
3452 // Note 1: different Linux may use different name for this property,
3453 // e.g. on Redhat AS-3 it is "hugetlb_pool".
3454 // Note 2: it's possible there's enough physical memory available but
3455 // they are so fragmented after a long run that they can't
3456 // coalesce into large pages. Try to reserve large pages when
3457 // the system is still "fresh".
3458 if (warn_on_failure) {
3459 jio_snprintf(msg, sizeof(msg), "Failed to reserve shared memory (errno = %d).", errno);
3460 warning("%s", msg);
3461 }
3462 return NULL;
3463 }
3464
3465 // attach to the region
3466 addr = (char*)shmat(shmid, req_addr, 0);
3467 int err = errno;
3468
3469 // Remove shmid. If shmat() is successful, the actual shared memory segment
3470 // will be deleted when it's detached by shmdt() or when the process
3471 // terminates. If shmat() is not successful this will remove the shared
3472 // segment immediately.
3473 shmctl(shmid, IPC_RMID, NULL);
3474
3475 if ((intptr_t)addr == -1) {
3476 if (warn_on_failure) {
3477 jio_snprintf(msg, sizeof(msg), "Failed to attach shared memory (errno = %d).", err);
3478 warning("%s", msg);
3479 }
3480 return NULL;
3481 }
3482
3483 return addr;
3484 }
3485
3486 static void warn_on_large_pages_failure(char* req_addr, size_t bytes,
3487 int error) {
3488 assert(error == ENOMEM, "Only expect to fail if no memory is available");
3489
3490 bool warn_on_failure = UseLargePages &&
3491 (!FLAG_IS_DEFAULT(UseLargePages) ||
3492 !FLAG_IS_DEFAULT(UseHugeTLBFS) ||
3493 !FLAG_IS_DEFAULT(LargePageSizeInBytes));
3494
3495 if (warn_on_failure) {
3496 char msg[128];
3497 jio_snprintf(msg, sizeof(msg), "Failed to reserve large pages memory req_addr: "
3498 PTR_FORMAT " bytes: " SIZE_FORMAT " (errno = %d).", req_addr, bytes, error);
3499 warning("%s", msg);
3500 }
3501 }
3502
3503 char* os::Linux::reserve_memory_special_huge_tlbfs_only(size_t bytes,
3504 char* req_addr,
3505 bool exec) {
3506 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages");
3507 assert(is_size_aligned(bytes, os::large_page_size()), "Unaligned size");
3508 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address");
3509
3510 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
3511 char* addr = (char*)::mmap(req_addr, bytes, prot,
3512 MAP_PRIVATE|MAP_ANONYMOUS|MAP_HUGETLB,
3513 -1, 0);
3514
3515 if (addr == MAP_FAILED) {
3516 warn_on_large_pages_failure(req_addr, bytes, errno);
3517 return NULL;
3518 }
3519
3520 assert(is_ptr_aligned(addr, os::large_page_size()), "Must be");
3521
3522 return addr;
3523 }
3524
3525 char* os::Linux::reserve_memory_special_huge_tlbfs_mixed(size_t bytes,
3526 size_t alignment,
3527 char* req_addr,
3528 bool exec) {
3529 size_t large_page_size = os::large_page_size();
3530
3531 assert(bytes >= large_page_size, "Shouldn't allocate large pages for small sizes");
3532
3533 // Allocate small pages.
3534
3535 char* start;
3536 if (req_addr != NULL) {
3537 assert(is_ptr_aligned(req_addr, alignment), "Must be");
3538 assert(is_size_aligned(bytes, alignment), "Must be");
3539 start = os::reserve_memory(bytes, req_addr);
3540 assert(start == NULL || start == req_addr, "Must be");
3541 } else {
3542 start = os::reserve_memory_aligned(bytes, alignment);
3543 }
3544
3545 if (start == NULL) {
3546 return NULL;
3547 }
3548
3549 assert(is_ptr_aligned(start, alignment), "Must be");
3550
3551 if (MemTracker::tracking_level() > NMT_minimal) {
3552 // os::reserve_memory_special will record this memory area.
3553 // Need to release it here to prevent overlapping reservations.
3554 Tracker tkr = MemTracker::get_virtual_memory_release_tracker();
3555 tkr.record((address)start, bytes);
3556 }
3557
3558 char* end = start + bytes;
3559
3560 // Find the regions of the allocated chunk that can be promoted to large pages.
3561 char* lp_start = (char*)align_ptr_up(start, large_page_size);
3562 char* lp_end = (char*)align_ptr_down(end, large_page_size);
3563
3564 size_t lp_bytes = lp_end - lp_start;
3565
3566 assert(is_size_aligned(lp_bytes, large_page_size), "Must be");
3567
3568 if (lp_bytes == 0) {
3569 // The mapped region doesn't even span the start and the end of a large page.
3570 // Fall back to allocate a non-special area.
3571 ::munmap(start, end - start);
3572 return NULL;
3573 }
3574
3575 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
3576
3577
3578 void* result;
3579
3580 if (start != lp_start) {
3581 result = ::mmap(start, lp_start - start, prot,
3582 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED,
3583 -1, 0);
3584 if (result == MAP_FAILED) {
3585 ::munmap(lp_start, end - lp_start);
3586 return NULL;
3587 }
3588 }
3589
3590 result = ::mmap(lp_start, lp_bytes, prot,
3591 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED|MAP_HUGETLB,
3592 -1, 0);
3593 if (result == MAP_FAILED) {
3594 warn_on_large_pages_failure(req_addr, bytes, errno);
3595 // If the mmap above fails, the large pages region will be unmapped and we
3596 // have regions before and after with small pages. Release these regions.
3597 //
3598 // | mapped | unmapped | mapped |
3599 // ^ ^ ^ ^
3600 // start lp_start lp_end end
3601 //
3602 ::munmap(start, lp_start - start);
3603 ::munmap(lp_end, end - lp_end);
3604 return NULL;
3605 }
3606
3607 if (lp_end != end) {
3608 result = ::mmap(lp_end, end - lp_end, prot,
3609 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED,
3610 -1, 0);
3611 if (result == MAP_FAILED) {
3612 ::munmap(start, lp_end - start);
3613 return NULL;
3614 }
3615 }
3616
3617 return start;
3618 }
3619
3620 char* os::Linux::reserve_memory_special_huge_tlbfs(size_t bytes,
3621 size_t alignment,
3622 char* req_addr,
3623 bool exec) {
3624 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages");
3625 assert(is_ptr_aligned(req_addr, alignment), "Must be");
3626 assert(is_power_of_2(alignment), "Must be");
3627 assert(is_power_of_2(os::large_page_size()), "Must be");
3628 assert(bytes >= os::large_page_size(), "Shouldn't allocate large pages for small sizes");
3629
3630 if (is_size_aligned(bytes, os::large_page_size()) && alignment <= os::large_page_size()) {
3631 return reserve_memory_special_huge_tlbfs_only(bytes, req_addr, exec);
3632 } else {
3633 return reserve_memory_special_huge_tlbfs_mixed(bytes, alignment, req_addr, exec);
3634 }
3635 }
3636
3637 char* os::reserve_memory_special(size_t bytes, size_t alignment,
3638 char* req_addr, bool exec) {
3639 assert(UseLargePages, "only for large pages");
3640
3641 char* addr;
3642 if (UseSHM) {
3643 addr = os::Linux::reserve_memory_special_shm(bytes, alignment, req_addr, exec);
3644 } else {
3645 assert(UseHugeTLBFS, "must be");
3646 addr = os::Linux::reserve_memory_special_huge_tlbfs(bytes, alignment, req_addr, exec);
3647 }
3648
3649 if (addr != NULL) {
3650 if (UseNUMAInterleaving) {
3651 numa_make_global(addr, bytes);
3652 }
3653
3654 // The memory is committed
3655 MemTracker::record_virtual_memory_reserve_and_commit((address)addr, bytes, CALLER_PC);
3656 }
3657
3658 return addr;
3659 }
3660
3661 bool os::Linux::release_memory_special_shm(char* base, size_t bytes) {
3662 // detaching the SHM segment will also delete it, see reserve_memory_special_shm()
3663 return shmdt(base) == 0;
3664 }
3665
3666 bool os::Linux::release_memory_special_huge_tlbfs(char* base, size_t bytes) {
3667 return pd_release_memory(base, bytes);
3668 }
3669
3670 bool os::release_memory_special(char* base, size_t bytes) {
3671 bool res;
3672 if (MemTracker::tracking_level() > NMT_minimal) {
3673 Tracker tkr = MemTracker::get_virtual_memory_release_tracker();
3674 res = os::Linux::release_memory_special_impl(base, bytes);
3675 if (res) {
3676 tkr.record((address)base, bytes);
3677 }
3678
3679 } else {
3680 res = os::Linux::release_memory_special_impl(base, bytes);
3681 }
3682 return res;
3683 }
3684
3685 bool os::Linux::release_memory_special_impl(char* base, size_t bytes) {
3686 assert(UseLargePages, "only for large pages");
3687 bool res;
3688
3689 if (UseSHM) {
3690 res = os::Linux::release_memory_special_shm(base, bytes);
3691 } else {
3692 assert(UseHugeTLBFS, "must be");
3693 res = os::Linux::release_memory_special_huge_tlbfs(base, bytes);
3694 }
3695 return res;
3696 }
3697
3698 size_t os::large_page_size() {
3699 return _large_page_size;
3700 }
3701
3702 // With SysV SHM the entire memory region must be allocated as shared
3703 // memory.
3704 // HugeTLBFS allows application to commit large page memory on demand.
3705 // However, when committing memory with HugeTLBFS fails, the region
3706 // that was supposed to be committed will lose the old reservation
3707 // and allow other threads to steal that memory region. Because of this
3708 // behavior we can't commit HugeTLBFS memory.
3709 bool os::can_commit_large_page_memory() {
3710 return UseTransparentHugePages;
3711 }
3712
3713 bool os::can_execute_large_page_memory() {
3714 return UseTransparentHugePages || UseHugeTLBFS;
3715 }
3716
3717 // Reserve memory at an arbitrary address, only if that area is
3718 // available (and not reserved for something else).
3719
3720 char* os::pd_attempt_reserve_memory_at(size_t bytes, char* requested_addr) {
3721 const int max_tries = 10;
3722 char* base[max_tries];
3723 size_t size[max_tries];
3724 const size_t gap = 0x000000;
3725
3726 // Assert only that the size is a multiple of the page size, since
3727 // that's all that mmap requires, and since that's all we really know
3728 // about at this low abstraction level. If we need higher alignment,
3729 // we can either pass an alignment to this method or verify alignment
3730 // in one of the methods further up the call chain. See bug 5044738.
3731 assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block");
3732
3733 // Repeatedly allocate blocks until the block is allocated at the
3734 // right spot. Give up after max_tries. Note that reserve_memory() will
3735 // automatically update _highest_vm_reserved_address if the call is
3736 // successful. The variable tracks the highest memory address every reserved
3737 // by JVM. It is used to detect heap-stack collision if running with
3738 // fixed-stack LinuxThreads. Because here we may attempt to reserve more
3739 // space than needed, it could confuse the collision detecting code. To
3740 // solve the problem, save current _highest_vm_reserved_address and
3741 // calculate the correct value before return.
3742 address old_highest = _highest_vm_reserved_address;
3743
3744 // Linux mmap allows caller to pass an address as hint; give it a try first,
3745 // if kernel honors the hint then we can return immediately.
3746 char * addr = anon_mmap(requested_addr, bytes, false);
3747 if (addr == requested_addr) {
3748 return requested_addr;
3749 }
3750
3751 if (addr != NULL) {
3752 // mmap() is successful but it fails to reserve at the requested address
3753 anon_munmap(addr, bytes);
3754 }
3755
3756 int i;
3757 for (i = 0; i < max_tries; ++i) {
3758 base[i] = reserve_memory(bytes);
3759
3760 if (base[i] != NULL) {
3761 // Is this the block we wanted?
3762 if (base[i] == requested_addr) {
3763 size[i] = bytes;
3764 break;
3765 }
3766
3767 // Does this overlap the block we wanted? Give back the overlapped
3768 // parts and try again.
3769
3770 size_t top_overlap = requested_addr + (bytes + gap) - base[i];
3771 if (top_overlap >= 0 && top_overlap < bytes) {
3772 unmap_memory(base[i], top_overlap);
3773 base[i] += top_overlap;
3774 size[i] = bytes - top_overlap;
3775 } else {
3776 size_t bottom_overlap = base[i] + bytes - requested_addr;
3777 if (bottom_overlap >= 0 && bottom_overlap < bytes) {
3778 unmap_memory(requested_addr, bottom_overlap);
3779 size[i] = bytes - bottom_overlap;
3780 } else {
3781 size[i] = bytes;
3782 }
3783 }
3784 }
3785 }
3786
3787 // Give back the unused reserved pieces.
3788
3789 for (int j = 0; j < i; ++j) {
3790 if (base[j] != NULL) {
3791 unmap_memory(base[j], size[j]);
3792 }
3793 }
3794
3795 if (i < max_tries) {
3796 _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes);
3797 return requested_addr;
3798 } else {
3799 _highest_vm_reserved_address = old_highest;
3800 return NULL;
3801 }
3802 }
3803
3804 size_t os::read(int fd, void *buf, unsigned int nBytes) {
3805 return ::read(fd, buf, nBytes);
3806 }
3807
3808 // Short sleep, direct OS call.
3809 //
3810 // Note: certain versions of Linux CFS scheduler (since 2.6.23) do not guarantee
3811 // sched_yield(2) will actually give up the CPU:
3812 //
3813 // * Alone on this pariticular CPU, keeps running.
3814 // * Before the introduction of "skip_buddy" with "compat_yield" disabled
3815 // (pre 2.6.39).
3816 //
3817 // So calling this with 0 is an alternative.
3818 //
3819 void os::naked_short_sleep(jlong ms) {
3820 struct timespec req;
3821
3822 assert(ms < 1000, "Un-interruptable sleep, short time use only");
3823 req.tv_sec = 0;
3824 if (ms > 0) {
3825 req.tv_nsec = (ms % 1000) * 1000000;
3826 } else {
3827 req.tv_nsec = 1;
3828 }
3829
3830 nanosleep(&req, NULL);
3831
3832 return;
3833 }
3834
3835 // Sleep forever; naked call to OS-specific sleep; use with CAUTION
3836 void os::infinite_sleep() {
3837 while (true) { // sleep forever ...
3838 ::sleep(100); // ... 100 seconds at a time
3839 }
3840 }
3841
3842 // Used to convert frequent JVM_Yield() to nops
3843 bool os::dont_yield() {
3844 return DontYieldALot;
3845 }
3846
3847 void os::naked_yield() {
3848 sched_yield();
3849 }
3850
3851 ////////////////////////////////////////////////////////////////////////////////
3852 // thread priority support
3853
3854 // Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER
3855 // only supports dynamic priority, static priority must be zero. For real-time
3856 // applications, Linux supports SCHED_RR which allows static priority (1-99).
3857 // However, for large multi-threaded applications, SCHED_RR is not only slower
3858 // than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out
3859 // of 5 runs - Sep 2005).
3860 //
3861 // The following code actually changes the niceness of kernel-thread/LWP. It
3862 // has an assumption that setpriority() only modifies one kernel-thread/LWP,
3863 // not the entire user process, and user level threads are 1:1 mapped to kernel
3864 // threads. It has always been the case, but could change in the future. For
3865 // this reason, the code should not be used as default (ThreadPriorityPolicy=0).
3866 // It is only used when ThreadPriorityPolicy=1 and requires root privilege.
3867
3868 int os::java_to_os_priority[CriticalPriority + 1] = {
3869 19, // 0 Entry should never be used
3870
3871 4, // 1 MinPriority
3872 3, // 2
3873 2, // 3
3874
3875 1, // 4
3876 0, // 5 NormPriority
3877 -1, // 6
3878
3879 -2, // 7
3880 -3, // 8
3881 -4, // 9 NearMaxPriority
3882
3883 -5, // 10 MaxPriority
3884
3885 -5 // 11 CriticalPriority
3886 };
3887
3888 static int prio_init() {
3889 if (ThreadPriorityPolicy == 1) {
3890 // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1
3891 // if effective uid is not root. Perhaps, a more elegant way of doing
3892 // this is to test CAP_SYS_NICE capability, but that will require libcap.so
3893 if (geteuid() != 0) {
3894 if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) {
3895 warning("-XX:ThreadPriorityPolicy requires root privilege on Linux");
3896 }
3897 ThreadPriorityPolicy = 0;
3898 }
3899 }
3900 if (UseCriticalJavaThreadPriority) {
3901 os::java_to_os_priority[MaxPriority] = os::java_to_os_priority[CriticalPriority];
3902 }
3903 return 0;
3904 }
3905
3906 OSReturn os::set_native_priority(Thread* thread, int newpri) {
3907 if (!UseThreadPriorities || ThreadPriorityPolicy == 0) return OS_OK;
3908
3909 int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri);
3910 return (ret == 0) ? OS_OK : OS_ERR;
3911 }
3912
3913 OSReturn os::get_native_priority(const Thread* const thread,
3914 int *priority_ptr) {
3915 if (!UseThreadPriorities || ThreadPriorityPolicy == 0) {
3916 *priority_ptr = java_to_os_priority[NormPriority];
3917 return OS_OK;
3918 }
3919
3920 errno = 0;
3921 *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id());
3922 return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR);
3923 }
3924
3925 // Hint to the underlying OS that a task switch would not be good.
3926 // Void return because it's a hint and can fail.
3927 void os::hint_no_preempt() {}
3928
3929 ////////////////////////////////////////////////////////////////////////////////
3930 // suspend/resume support
3931
3932 // the low-level signal-based suspend/resume support is a remnant from the
3933 // old VM-suspension that used to be for java-suspension, safepoints etc,
3934 // within hotspot. Now there is a single use-case for this:
3935 // - calling get_thread_pc() on the VMThread by the flat-profiler task
3936 // that runs in the watcher thread.
3937 // The remaining code is greatly simplified from the more general suspension
3938 // code that used to be used.
3939 //
3940 // The protocol is quite simple:
3941 // - suspend:
3942 // - sends a signal to the target thread
3943 // - polls the suspend state of the osthread using a yield loop
3944 // - target thread signal handler (SR_handler) sets suspend state
3945 // and blocks in sigsuspend until continued
3946 // - resume:
3947 // - sets target osthread state to continue
3948 // - sends signal to end the sigsuspend loop in the SR_handler
3949 //
3950 // Note that the SR_lock plays no role in this suspend/resume protocol.
3951
3952 static void resume_clear_context(OSThread *osthread) {
3953 osthread->set_ucontext(NULL);
3954 osthread->set_siginfo(NULL);
3955 }
3956
3957 static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo,
3958 ucontext_t* context) {
3959 osthread->set_ucontext(context);
3960 osthread->set_siginfo(siginfo);
3961 }
3962
3963 // Handler function invoked when a thread's execution is suspended or
3964 // resumed. We have to be careful that only async-safe functions are
3965 // called here (Note: most pthread functions are not async safe and
3966 // should be avoided.)
3967 //
3968 // Note: sigwait() is a more natural fit than sigsuspend() from an
3969 // interface point of view, but sigwait() prevents the signal hander
3970 // from being run. libpthread would get very confused by not having
3971 // its signal handlers run and prevents sigwait()'s use with the
3972 // mutex granting granting signal.
3973 //
3974 // Currently only ever called on the VMThread and JavaThreads (PC sampling)
3975 //
3976 static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) {
3977 // Save and restore errno to avoid confusing native code with EINTR
3978 // after sigsuspend.
3979 int old_errno = errno;
3980
3981 Thread* thread = Thread::current();
3982 OSThread* osthread = thread->osthread();
3983 assert(thread->is_VM_thread() || thread->is_Java_thread(), "Must be VMThread or JavaThread");
3984
3985 os::SuspendResume::State current = osthread->sr.state();
3986 if (current == os::SuspendResume::SR_SUSPEND_REQUEST) {
3987 suspend_save_context(osthread, siginfo, context);
3988
3989 // attempt to switch the state, we assume we had a SUSPEND_REQUEST
3990 os::SuspendResume::State state = osthread->sr.suspended();
3991 if (state == os::SuspendResume::SR_SUSPENDED) {
3992 sigset_t suspend_set; // signals for sigsuspend()
3993
3994 // get current set of blocked signals and unblock resume signal
3995 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set);
3996 sigdelset(&suspend_set, SR_signum);
3997
3998 sr_semaphore.signal();
3999 // wait here until we are resumed
4000 while (1) {
4001 sigsuspend(&suspend_set);
4002
4003 os::SuspendResume::State result = osthread->sr.running();
4004 if (result == os::SuspendResume::SR_RUNNING) {
4005 sr_semaphore.signal();
4006 break;
4007 }
4008 }
4009
4010 } else if (state == os::SuspendResume::SR_RUNNING) {
4011 // request was cancelled, continue
4012 } else {
4013 ShouldNotReachHere();
4014 }
4015
4016 resume_clear_context(osthread);
4017 } else if (current == os::SuspendResume::SR_RUNNING) {
4018 // request was cancelled, continue
4019 } else if (current == os::SuspendResume::SR_WAKEUP_REQUEST) {
4020 // ignore
4021 } else {
4022 // ignore
4023 }
4024
4025 errno = old_errno;
4026 }
4027
4028
4029 static int SR_initialize() {
4030 struct sigaction act;
4031 char *s;
4032 // Get signal number to use for suspend/resume
4033 if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) {
4034 int sig = ::strtol(s, 0, 10);
4035 if (sig > 0 || sig < _NSIG) {
4036 SR_signum = sig;
4037 }
4038 }
4039
4040 assert(SR_signum > SIGSEGV && SR_signum > SIGBUS,
4041 "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769");
4042
4043 sigemptyset(&SR_sigset);
4044 sigaddset(&SR_sigset, SR_signum);
4045
4046 // Set up signal handler for suspend/resume
4047 act.sa_flags = SA_RESTART|SA_SIGINFO;
4048 act.sa_handler = (void (*)(int)) SR_handler;
4049
4050 // SR_signum is blocked by default.
4051 // 4528190 - We also need to block pthread restart signal (32 on all
4052 // supported Linux platforms). Note that LinuxThreads need to block
4053 // this signal for all threads to work properly. So we don't have
4054 // to use hard-coded signal number when setting up the mask.
4055 pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask);
4056
4057 if (sigaction(SR_signum, &act, 0) == -1) {
4058 return -1;
4059 }
4060
4061 // Save signal flag
4062 os::Linux::set_our_sigflags(SR_signum, act.sa_flags);
4063 return 0;
4064 }
4065
4066 static int sr_notify(OSThread* osthread) {
4067 int status = pthread_kill(osthread->pthread_id(), SR_signum);
4068 assert_status(status == 0, status, "pthread_kill");
4069 return status;
4070 }
4071
4072 // "Randomly" selected value for how long we want to spin
4073 // before bailing out on suspending a thread, also how often
4074 // we send a signal to a thread we want to resume
4075 static const int RANDOMLY_LARGE_INTEGER = 1000000;
4076 static const int RANDOMLY_LARGE_INTEGER2 = 100;
4077
4078 // returns true on success and false on error - really an error is fatal
4079 // but this seems the normal response to library errors
4080 static bool do_suspend(OSThread* osthread) {
4081 assert(osthread->sr.is_running(), "thread should be running");
4082 assert(!sr_semaphore.trywait(), "semaphore has invalid state");
4083
4084 // mark as suspended and send signal
4085 if (osthread->sr.request_suspend() != os::SuspendResume::SR_SUSPEND_REQUEST) {
4086 // failed to switch, state wasn't running?
4087 ShouldNotReachHere();
4088 return false;
4089 }
4090
4091 if (sr_notify(osthread) != 0) {
4092 ShouldNotReachHere();
4093 }
4094
4095 // managed to send the signal and switch to SUSPEND_REQUEST, now wait for SUSPENDED
4096 while (true) {
4097 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) {
4098 break;
4099 } else {
4100 // timeout
4101 os::SuspendResume::State cancelled = osthread->sr.cancel_suspend();
4102 if (cancelled == os::SuspendResume::SR_RUNNING) {
4103 return false;
4104 } else if (cancelled == os::SuspendResume::SR_SUSPENDED) {
4105 // make sure that we consume the signal on the semaphore as well
4106 sr_semaphore.wait();
4107 break;
4108 } else {
4109 ShouldNotReachHere();
4110 return false;
4111 }
4112 }
4113 }
4114
4115 guarantee(osthread->sr.is_suspended(), "Must be suspended");
4116 return true;
4117 }
4118
4119 static void do_resume(OSThread* osthread) {
4120 assert(osthread->sr.is_suspended(), "thread should be suspended");
4121 assert(!sr_semaphore.trywait(), "invalid semaphore state");
4122
4123 if (osthread->sr.request_wakeup() != os::SuspendResume::SR_WAKEUP_REQUEST) {
4124 // failed to switch to WAKEUP_REQUEST
4125 ShouldNotReachHere();
4126 return;
4127 }
4128
4129 while (true) {
4130 if (sr_notify(osthread) == 0) {
4131 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) {
4132 if (osthread->sr.is_running()) {
4133 return;
4134 }
4135 }
4136 } else {
4137 ShouldNotReachHere();
4138 }
4139 }
4140
4141 guarantee(osthread->sr.is_running(), "Must be running!");
4142 }
4143
4144 ///////////////////////////////////////////////////////////////////////////////////
4145 // signal handling (except suspend/resume)
4146
4147 // This routine may be used by user applications as a "hook" to catch signals.
4148 // The user-defined signal handler must pass unrecognized signals to this
4149 // routine, and if it returns true (non-zero), then the signal handler must
4150 // return immediately. If the flag "abort_if_unrecognized" is true, then this
4151 // routine will never retun false (zero), but instead will execute a VM panic
4152 // routine kill the process.
4153 //
4154 // If this routine returns false, it is OK to call it again. This allows
4155 // the user-defined signal handler to perform checks either before or after
4156 // the VM performs its own checks. Naturally, the user code would be making
4157 // a serious error if it tried to handle an exception (such as a null check
4158 // or breakpoint) that the VM was generating for its own correct operation.
4159 //
4160 // This routine may recognize any of the following kinds of signals:
4161 // SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1.
4162 // It should be consulted by handlers for any of those signals.
4163 //
4164 // The caller of this routine must pass in the three arguments supplied
4165 // to the function referred to in the "sa_sigaction" (not the "sa_handler")
4166 // field of the structure passed to sigaction(). This routine assumes that
4167 // the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART.
4168 //
4169 // Note that the VM will print warnings if it detects conflicting signal
4170 // handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers".
4171 //
4172 extern "C" JNIEXPORT int JVM_handle_linux_signal(int signo,
4173 siginfo_t* siginfo,
4174 void* ucontext,
4175 int abort_if_unrecognized);
4176
4177 void signalHandler(int sig, siginfo_t* info, void* uc) {
4178 assert(info != NULL && uc != NULL, "it must be old kernel");
4179 int orig_errno = errno; // Preserve errno value over signal handler.
4180 JVM_handle_linux_signal(sig, info, uc, true);
4181 errno = orig_errno;
4182 }
4183
4184
4185 // This boolean allows users to forward their own non-matching signals
4186 // to JVM_handle_linux_signal, harmlessly.
4187 bool os::Linux::signal_handlers_are_installed = false;
4188
4189 // For signal-chaining
4190 struct sigaction os::Linux::sigact[MAXSIGNUM];
4191 unsigned int os::Linux::sigs = 0;
4192 bool os::Linux::libjsig_is_loaded = false;
4193 typedef struct sigaction *(*get_signal_t)(int);
4194 get_signal_t os::Linux::get_signal_action = NULL;
4195
4196 struct sigaction* os::Linux::get_chained_signal_action(int sig) {
4197 struct sigaction *actp = NULL;
4198
4199 if (libjsig_is_loaded) {
4200 // Retrieve the old signal handler from libjsig
4201 actp = (*get_signal_action)(sig);
4202 }
4203 if (actp == NULL) {
4204 // Retrieve the preinstalled signal handler from jvm
4205 actp = get_preinstalled_handler(sig);
4206 }
4207
4208 return actp;
4209 }
4210
4211 static bool call_chained_handler(struct sigaction *actp, int sig,
4212 siginfo_t *siginfo, void *context) {
4213 // Call the old signal handler
4214 if (actp->sa_handler == SIG_DFL) {
4215 // It's more reasonable to let jvm treat it as an unexpected exception
4216 // instead of taking the default action.
4217 return false;
4218 } else if (actp->sa_handler != SIG_IGN) {
4219 if ((actp->sa_flags & SA_NODEFER) == 0) {
4220 // automaticlly block the signal
4221 sigaddset(&(actp->sa_mask), sig);
4222 }
4223
4224 sa_handler_t hand;
4225 sa_sigaction_t sa;
4226 bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0;
4227 // retrieve the chained handler
4228 if (siginfo_flag_set) {
4229 sa = actp->sa_sigaction;
4230 } else {
4231 hand = actp->sa_handler;
4232 }
4233
4234 if ((actp->sa_flags & SA_RESETHAND) != 0) {
4235 actp->sa_handler = SIG_DFL;
4236 }
4237
4238 // try to honor the signal mask
4239 sigset_t oset;
4240 pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset);
4241
4242 // call into the chained handler
4243 if (siginfo_flag_set) {
4244 (*sa)(sig, siginfo, context);
4245 } else {
4246 (*hand)(sig);
4247 }
4248
4249 // restore the signal mask
4250 pthread_sigmask(SIG_SETMASK, &oset, 0);
4251 }
4252 // Tell jvm's signal handler the signal is taken care of.
4253 return true;
4254 }
4255
4256 bool os::Linux::chained_handler(int sig, siginfo_t* siginfo, void* context) {
4257 bool chained = false;
4258 // signal-chaining
4259 if (UseSignalChaining) {
4260 struct sigaction *actp = get_chained_signal_action(sig);
4261 if (actp != NULL) {
4262 chained = call_chained_handler(actp, sig, siginfo, context);
4263 }
4264 }
4265 return chained;
4266 }
4267
4268 struct sigaction* os::Linux::get_preinstalled_handler(int sig) {
4269 if ((((unsigned int)1 << sig) & sigs) != 0) {
4270 return &sigact[sig];
4271 }
4272 return NULL;
4273 }
4274
4275 void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) {
4276 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4277 sigact[sig] = oldAct;
4278 sigs |= (unsigned int)1 << sig;
4279 }
4280
4281 // for diagnostic
4282 int os::Linux::sigflags[MAXSIGNUM];
4283
4284 int os::Linux::get_our_sigflags(int sig) {
4285 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4286 return sigflags[sig];
4287 }
4288
4289 void os::Linux::set_our_sigflags(int sig, int flags) {
4290 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4291 sigflags[sig] = flags;
4292 }
4293
4294 void os::Linux::set_signal_handler(int sig, bool set_installed) {
4295 // Check for overwrite.
4296 struct sigaction oldAct;
4297 sigaction(sig, (struct sigaction*)NULL, &oldAct);
4298
4299 void* oldhand = oldAct.sa_sigaction
4300 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction)
4301 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler);
4302 if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) &&
4303 oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) &&
4304 oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) {
4305 if (AllowUserSignalHandlers || !set_installed) {
4306 // Do not overwrite; user takes responsibility to forward to us.
4307 return;
4308 } else if (UseSignalChaining) {
4309 // save the old handler in jvm
4310 save_preinstalled_handler(sig, oldAct);
4311 // libjsig also interposes the sigaction() call below and saves the
4312 // old sigaction on it own.
4313 } else {
4314 fatal(err_msg("Encountered unexpected pre-existing sigaction handler "
4315 "%#lx for signal %d.", (long)oldhand, sig));
4316 }
4317 }
4318
4319 struct sigaction sigAct;
4320 sigfillset(&(sigAct.sa_mask));
4321 sigAct.sa_handler = SIG_DFL;
4322 if (!set_installed) {
4323 sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
4324 } else {
4325 sigAct.sa_sigaction = signalHandler;
4326 sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
4327 }
4328 // Save flags, which are set by ours
4329 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4330 sigflags[sig] = sigAct.sa_flags;
4331
4332 int ret = sigaction(sig, &sigAct, &oldAct);
4333 assert(ret == 0, "check");
4334
4335 void* oldhand2 = oldAct.sa_sigaction
4336 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction)
4337 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler);
4338 assert(oldhand2 == oldhand, "no concurrent signal handler installation");
4339 }
4340
4341 // install signal handlers for signals that HotSpot needs to
4342 // handle in order to support Java-level exception handling.
4343
4344 void os::Linux::install_signal_handlers() {
4345 if (!signal_handlers_are_installed) {
4346 signal_handlers_are_installed = true;
4347
4348 // signal-chaining
4349 typedef void (*signal_setting_t)();
4350 signal_setting_t begin_signal_setting = NULL;
4351 signal_setting_t end_signal_setting = NULL;
4352 begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
4353 dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting"));
4354 if (begin_signal_setting != NULL) {
4355 end_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
4356 dlsym(RTLD_DEFAULT, "JVM_end_signal_setting"));
4357 get_signal_action = CAST_TO_FN_PTR(get_signal_t,
4358 dlsym(RTLD_DEFAULT, "JVM_get_signal_action"));
4359 libjsig_is_loaded = true;
4360 assert(UseSignalChaining, "should enable signal-chaining");
4361 }
4362 if (libjsig_is_loaded) {
4363 // Tell libjsig jvm is setting signal handlers
4364 (*begin_signal_setting)();
4365 }
4366
4367 set_signal_handler(SIGSEGV, true);
4368 set_signal_handler(SIGPIPE, true);
4369 set_signal_handler(SIGBUS, true);
4370 set_signal_handler(SIGILL, true);
4371 set_signal_handler(SIGFPE, true);
4372 #if defined(PPC64)
4373 set_signal_handler(SIGTRAP, true);
4374 #endif
4375 set_signal_handler(SIGXFSZ, true);
4376
4377 if (libjsig_is_loaded) {
4378 // Tell libjsig jvm finishes setting signal handlers
4379 (*end_signal_setting)();
4380 }
4381
4382 // We don't activate signal checker if libjsig is in place, we trust ourselves
4383 // and if UserSignalHandler is installed all bets are off.
4384 // Log that signal checking is off only if -verbose:jni is specified.
4385 if (CheckJNICalls) {
4386 if (libjsig_is_loaded) {
4387 if (PrintJNIResolving) {
4388 tty->print_cr("Info: libjsig is activated, all active signal checking is disabled");
4389 }
4390 check_signals = false;
4391 }
4392 if (AllowUserSignalHandlers) {
4393 if (PrintJNIResolving) {
4394 tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled");
4395 }
4396 check_signals = false;
4397 }
4398 }
4399 }
4400 }
4401
4402 // This is the fastest way to get thread cpu time on Linux.
4403 // Returns cpu time (user+sys) for any thread, not only for current.
4404 // POSIX compliant clocks are implemented in the kernels 2.6.16+.
4405 // It might work on 2.6.10+ with a special kernel/glibc patch.
4406 // For reference, please, see IEEE Std 1003.1-2004:
4407 // http://www.unix.org/single_unix_specification
4408
4409 jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) {
4410 struct timespec tp;
4411 int rc = os::Linux::clock_gettime(clockid, &tp);
4412 assert(rc == 0, "clock_gettime is expected to return 0 code");
4413
4414 return (tp.tv_sec * NANOSECS_PER_SEC) + tp.tv_nsec;
4415 }
4416
4417 /////
4418 // glibc on Linux platform uses non-documented flag
4419 // to indicate, that some special sort of signal
4420 // trampoline is used.
4421 // We will never set this flag, and we should
4422 // ignore this flag in our diagnostic
4423 #ifdef SIGNIFICANT_SIGNAL_MASK
4424 #undef SIGNIFICANT_SIGNAL_MASK
4425 #endif
4426 #define SIGNIFICANT_SIGNAL_MASK (~0x04000000)
4427
4428 static const char* get_signal_handler_name(address handler,
4429 char* buf, int buflen) {
4430 int offset;
4431 bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset);
4432 if (found) {
4433 // skip directory names
4434 const char *p1, *p2;
4435 p1 = buf;
4436 size_t len = strlen(os::file_separator());
4437 while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len;
4438 jio_snprintf(buf, buflen, "%s+0x%x", p1, offset);
4439 } else {
4440 jio_snprintf(buf, buflen, PTR_FORMAT, handler);
4441 }
4442 return buf;
4443 }
4444
4445 static void print_signal_handler(outputStream* st, int sig,
4446 char* buf, size_t buflen) {
4447 struct sigaction sa;
4448
4449 sigaction(sig, NULL, &sa);
4450
4451 // See comment for SIGNIFICANT_SIGNAL_MASK define
4452 sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
4453
4454 st->print("%s: ", os::exception_name(sig, buf, buflen));
4455
4456 address handler = (sa.sa_flags & SA_SIGINFO)
4457 ? CAST_FROM_FN_PTR(address, sa.sa_sigaction)
4458 : CAST_FROM_FN_PTR(address, sa.sa_handler);
4459
4460 if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) {
4461 st->print("SIG_DFL");
4462 } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) {
4463 st->print("SIG_IGN");
4464 } else {
4465 st->print("[%s]", get_signal_handler_name(handler, buf, buflen));
4466 }
4467
4468 st->print(", sa_mask[0]=");
4469 os::Posix::print_signal_set_short(st, &sa.sa_mask);
4470
4471 address rh = VMError::get_resetted_sighandler(sig);
4472 // May be, handler was resetted by VMError?
4473 if (rh != NULL) {
4474 handler = rh;
4475 sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK;
4476 }
4477
4478 st->print(", sa_flags=");
4479 os::Posix::print_sa_flags(st, sa.sa_flags);
4480
4481 // Check: is it our handler?
4482 if (handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) ||
4483 handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) {
4484 // It is our signal handler
4485 // check for flags, reset system-used one!
4486 if ((int)sa.sa_flags != os::Linux::get_our_sigflags(sig)) {
4487 st->print(
4488 ", flags was changed from " PTR32_FORMAT ", consider using jsig library",
4489 os::Linux::get_our_sigflags(sig));
4490 }
4491 }
4492 st->cr();
4493 }
4494
4495
4496 #define DO_SIGNAL_CHECK(sig) \
4497 do { \
4498 if (!sigismember(&check_signal_done, sig)) { \
4499 os::Linux::check_signal_handler(sig); \
4500 } \
4501 } while (0)
4502
4503 // This method is a periodic task to check for misbehaving JNI applications
4504 // under CheckJNI, we can add any periodic checks here
4505
4506 void os::run_periodic_checks() {
4507 if (check_signals == false) return;
4508
4509 // SEGV and BUS if overridden could potentially prevent
4510 // generation of hs*.log in the event of a crash, debugging
4511 // such a case can be very challenging, so we absolutely
4512 // check the following for a good measure:
4513 DO_SIGNAL_CHECK(SIGSEGV);
4514 DO_SIGNAL_CHECK(SIGILL);
4515 DO_SIGNAL_CHECK(SIGFPE);
4516 DO_SIGNAL_CHECK(SIGBUS);
4517 DO_SIGNAL_CHECK(SIGPIPE);
4518 DO_SIGNAL_CHECK(SIGXFSZ);
4519 #if defined(PPC64)
4520 DO_SIGNAL_CHECK(SIGTRAP);
4521 #endif
4522
4523 // ReduceSignalUsage allows the user to override these handlers
4524 // see comments at the very top and jvm_solaris.h
4525 if (!ReduceSignalUsage) {
4526 DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL);
4527 DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL);
4528 DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL);
4529 DO_SIGNAL_CHECK(BREAK_SIGNAL);
4530 }
4531
4532 DO_SIGNAL_CHECK(SR_signum);
4533 DO_SIGNAL_CHECK(INTERRUPT_SIGNAL);
4534 }
4535
4536 typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *);
4537
4538 static os_sigaction_t os_sigaction = NULL;
4539
4540 void os::Linux::check_signal_handler(int sig) {
4541 char buf[O_BUFLEN];
4542 address jvmHandler = NULL;
4543
4544
4545 struct sigaction act;
4546 if (os_sigaction == NULL) {
4547 // only trust the default sigaction, in case it has been interposed
4548 os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction");
4549 if (os_sigaction == NULL) return;
4550 }
4551
4552 os_sigaction(sig, (struct sigaction*)NULL, &act);
4553
4554
4555 act.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
4556
4557 address thisHandler = (act.sa_flags & SA_SIGINFO)
4558 ? CAST_FROM_FN_PTR(address, act.sa_sigaction)
4559 : CAST_FROM_FN_PTR(address, act.sa_handler);
4560
4561
4562 switch (sig) {
4563 case SIGSEGV:
4564 case SIGBUS:
4565 case SIGFPE:
4566 case SIGPIPE:
4567 case SIGILL:
4568 case SIGXFSZ:
4569 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler);
4570 break;
4571
4572 case SHUTDOWN1_SIGNAL:
4573 case SHUTDOWN2_SIGNAL:
4574 case SHUTDOWN3_SIGNAL:
4575 case BREAK_SIGNAL:
4576 jvmHandler = (address)user_handler();
4577 break;
4578
4579 case INTERRUPT_SIGNAL:
4580 jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL);
4581 break;
4582
4583 default:
4584 if (sig == SR_signum) {
4585 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler);
4586 } else {
4587 return;
4588 }
4589 break;
4590 }
4591
4592 if (thisHandler != jvmHandler) {
4593 tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN));
4594 tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN));
4595 tty->print_cr(" found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN));
4596 // No need to check this sig any longer
4597 sigaddset(&check_signal_done, sig);
4598 // Running under non-interactive shell, SHUTDOWN2_SIGNAL will be reassigned SIG_IGN
4599 if (sig == SHUTDOWN2_SIGNAL && !isatty(fileno(stdin))) {
4600 tty->print_cr("Running in non-interactive shell, %s handler is replaced by shell",
4601 exception_name(sig, buf, O_BUFLEN));
4602 }
4603 } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) {
4604 tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN));
4605 tty->print("expected:" PTR32_FORMAT, os::Linux::get_our_sigflags(sig));
4606 tty->print_cr(" found:" PTR32_FORMAT, act.sa_flags);
4607 // No need to check this sig any longer
4608 sigaddset(&check_signal_done, sig);
4609 }
4610
4611 // Dump all the signal
4612 if (sigismember(&check_signal_done, sig)) {
4613 print_signal_handlers(tty, buf, O_BUFLEN);
4614 }
4615 }
4616
4617 extern void report_error(char* file_name, int line_no, char* title,
4618 char* format, ...);
4619
4620 extern bool signal_name(int signo, char* buf, size_t len);
4621
4622 const char* os::exception_name(int exception_code, char* buf, size_t size) {
4623 if (0 < exception_code && exception_code <= SIGRTMAX) {
4624 // signal
4625 if (!signal_name(exception_code, buf, size)) {
4626 jio_snprintf(buf, size, "SIG%d", exception_code);
4627 }
4628 return buf;
4629 } else {
4630 return NULL;
4631 }
4632 }
4633
4634 // this is called _before_ the most of global arguments have been parsed
4635 void os::init(void) {
4636 char dummy; // used to get a guess on initial stack address
4637 // first_hrtime = gethrtime();
4638
4639 // With LinuxThreads the JavaMain thread pid (primordial thread)
4640 // is different than the pid of the java launcher thread.
4641 // So, on Linux, the launcher thread pid is passed to the VM
4642 // via the sun.java.launcher.pid property.
4643 // Use this property instead of getpid() if it was correctly passed.
4644 // See bug 6351349.
4645 pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid();
4646
4647 _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid();
4648
4649 clock_tics_per_sec = sysconf(_SC_CLK_TCK);
4650
4651 init_random(1234567);
4652
4653 ThreadCritical::initialize();
4654
4655 Linux::set_page_size(sysconf(_SC_PAGESIZE));
4656 if (Linux::page_size() == -1) {
4657 fatal(err_msg("os_linux.cpp: os::init: sysconf failed (%s)",
4658 strerror(errno)));
4659 }
4660 init_page_sizes((size_t) Linux::page_size());
4661
4662 Linux::initialize_system_info();
4663
4664 // main_thread points to the aboriginal thread
4665 Linux::_main_thread = pthread_self();
4666
4667 Linux::clock_init();
4668 initial_time_count = javaTimeNanos();
4669
4670 // pthread_condattr initialization for monotonic clock
4671 int status;
4672 pthread_condattr_t* _condattr = os::Linux::condAttr();
4673 if ((status = pthread_condattr_init(_condattr)) != 0) {
4674 fatal(err_msg("pthread_condattr_init: %s", strerror(status)));
4675 }
4676 // Only set the clock if CLOCK_MONOTONIC is available
4677 if (os::supports_monotonic_clock()) {
4678 if ((status = pthread_condattr_setclock(_condattr, CLOCK_MONOTONIC)) != 0) {
4679 if (status == EINVAL) {
4680 warning("Unable to use monotonic clock with relative timed-waits" \
4681 " - changes to the time-of-day clock may have adverse affects");
4682 } else {
4683 fatal(err_msg("pthread_condattr_setclock: %s", strerror(status)));
4684 }
4685 }
4686 }
4687 // else it defaults to CLOCK_REALTIME
4688
4689 pthread_mutex_init(&dl_mutex, NULL);
4690
4691 // If the pagesize of the VM is greater than 8K determine the appropriate
4692 // number of initial guard pages. The user can change this with the
4693 // command line arguments, if needed.
4694 if (vm_page_size() > (int)Linux::vm_default_page_size()) {
4695 StackYellowPages = 1;
4696 StackRedPages = 1;
4697 StackShadowPages = round_to((StackShadowPages*Linux::vm_default_page_size()), vm_page_size()) / vm_page_size();
4698 }
4699 }
4700
4701 // To install functions for atexit system call
4702 extern "C" {
4703 static void perfMemory_exit_helper() {
4704 perfMemory_exit();
4705 }
4706 }
4707
4708 // this is called _after_ the global arguments have been parsed
4709 jint os::init_2(void) {
4710 Linux::fast_thread_clock_init();
4711
4712 // Allocate a single page and mark it as readable for safepoint polling
4713 address polling_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
4714 guarantee(polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page");
4715
4716 os::set_polling_page(polling_page);
4717
4718 #ifndef PRODUCT
4719 if (Verbose && PrintMiscellaneous) {
4720 tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n",
4721 (intptr_t)polling_page);
4722 }
4723 #endif
4724
4725 if (!UseMembar) {
4726 address mem_serialize_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
4727 guarantee(mem_serialize_page != MAP_FAILED, "mmap Failed for memory serialize page");
4728 os::set_memory_serialize_page(mem_serialize_page);
4729
4730 #ifndef PRODUCT
4731 if (Verbose && PrintMiscellaneous) {
4732 tty->print("[Memory Serialize Page address: " INTPTR_FORMAT "]\n",
4733 (intptr_t)mem_serialize_page);
4734 }
4735 #endif
4736 }
4737
4738 // initialize suspend/resume support - must do this before signal_sets_init()
4739 if (SR_initialize() != 0) {
4740 perror("SR_initialize failed");
4741 return JNI_ERR;
4742 }
4743
4744 Linux::signal_sets_init();
4745 Linux::install_signal_handlers();
4746
4747 // Check minimum allowable stack size for thread creation and to initialize
4748 // the java system classes, including StackOverflowError - depends on page
4749 // size. Add a page for compiler2 recursion in main thread.
4750 // Add in 2*BytesPerWord times page size to account for VM stack during
4751 // class initialization depending on 32 or 64 bit VM.
4752 os::Linux::min_stack_allowed = MAX2(os::Linux::min_stack_allowed,
4753 (size_t)(StackYellowPages+StackRedPages+StackShadowPages) * Linux::page_size() +
4754 (2*BytesPerWord COMPILER2_PRESENT(+1)) * Linux::vm_default_page_size());
4755
4756 size_t threadStackSizeInBytes = ThreadStackSize * K;
4757 if (threadStackSizeInBytes != 0 &&
4758 threadStackSizeInBytes < os::Linux::min_stack_allowed) {
4759 tty->print_cr("\nThe stack size specified is too small, "
4760 "Specify at least %dk",
4761 os::Linux::min_stack_allowed/ K);
4762 return JNI_ERR;
4763 }
4764
4765 // Make the stack size a multiple of the page size so that
4766 // the yellow/red zones can be guarded.
4767 JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes,
4768 vm_page_size()));
4769
4770 Linux::capture_initial_stack(JavaThread::stack_size_at_create());
4771
4772 #if defined(IA32)
4773 workaround_expand_exec_shield_cs_limit();
4774 #endif
4775
4776 Linux::libpthread_init();
4777 if (PrintMiscellaneous && (Verbose || WizardMode)) {
4778 tty->print_cr("[HotSpot is running with %s, %s(%s)]\n",
4779 Linux::glibc_version(), Linux::libpthread_version(),
4780 Linux::is_floating_stack() ? "floating stack" : "fixed stack");
4781 }
4782
4783 if (UseNUMA) {
4784 if (!Linux::libnuma_init()) {
4785 UseNUMA = false;
4786 } else {
4787 if ((Linux::numa_max_node() < 1)) {
4788 // There's only one node(they start from 0), disable NUMA.
4789 UseNUMA = false;
4790 }
4791 }
4792 // With SHM and HugeTLBFS large pages we cannot uncommit a page, so there's no way
4793 // we can make the adaptive lgrp chunk resizing work. If the user specified
4794 // both UseNUMA and UseLargePages (or UseSHM/UseHugeTLBFS) on the command line - warn and
4795 // disable adaptive resizing.
4796 if (UseNUMA && UseLargePages && !can_commit_large_page_memory()) {
4797 if (FLAG_IS_DEFAULT(UseNUMA)) {
4798 UseNUMA = false;
4799 } else {
4800 if (FLAG_IS_DEFAULT(UseLargePages) &&
4801 FLAG_IS_DEFAULT(UseSHM) &&
4802 FLAG_IS_DEFAULT(UseHugeTLBFS)) {
4803 UseLargePages = false;
4804 } else {
4805 warning("UseNUMA is not fully compatible with SHM/HugeTLBFS large pages, disabling adaptive resizing");
4806 UseAdaptiveSizePolicy = false;
4807 UseAdaptiveNUMAChunkSizing = false;
4808 }
4809 }
4810 }
4811 if (!UseNUMA && ForceNUMA) {
4812 UseNUMA = true;
4813 }
4814 }
4815
4816 if (MaxFDLimit) {
4817 // set the number of file descriptors to max. print out error
4818 // if getrlimit/setrlimit fails but continue regardless.
4819 struct rlimit nbr_files;
4820 int status = getrlimit(RLIMIT_NOFILE, &nbr_files);
4821 if (status != 0) {
4822 if (PrintMiscellaneous && (Verbose || WizardMode)) {
4823 perror("os::init_2 getrlimit failed");
4824 }
4825 } else {
4826 nbr_files.rlim_cur = nbr_files.rlim_max;
4827 status = setrlimit(RLIMIT_NOFILE, &nbr_files);
4828 if (status != 0) {
4829 if (PrintMiscellaneous && (Verbose || WizardMode)) {
4830 perror("os::init_2 setrlimit failed");
4831 }
4832 }
4833 }
4834 }
4835
4836 // Initialize lock used to serialize thread creation (see os::create_thread)
4837 Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false));
4838
4839 // at-exit methods are called in the reverse order of their registration.
4840 // atexit functions are called on return from main or as a result of a
4841 // call to exit(3C). There can be only 32 of these functions registered
4842 // and atexit() does not set errno.
4843
4844 if (PerfAllowAtExitRegistration) {
4845 // only register atexit functions if PerfAllowAtExitRegistration is set.
4846 // atexit functions can be delayed until process exit time, which
4847 // can be problematic for embedded VM situations. Embedded VMs should
4848 // call DestroyJavaVM() to assure that VM resources are released.
4849
4850 // note: perfMemory_exit_helper atexit function may be removed in
4851 // the future if the appropriate cleanup code can be added to the
4852 // VM_Exit VMOperation's doit method.
4853 if (atexit(perfMemory_exit_helper) != 0) {
4854 warning("os::init_2 atexit(perfMemory_exit_helper) failed");
4855 }
4856 }
4857
4858 // initialize thread priority policy
4859 prio_init();
4860
4861 return JNI_OK;
4862 }
4863
4864 // this is called at the end of vm_initialization
4865 void os::init_3(void) {
4866 #ifdef JAVASE_EMBEDDED
4867 // Start the MemNotifyThread
4868 if (LowMemoryProtection) {
4869 MemNotifyThread::start();
4870 }
4871 return;
4872 #endif
4873 }
4874
4875 // Mark the polling page as unreadable
4876 void os::make_polling_page_unreadable(void) {
4877 if (!guard_memory((char*)_polling_page, Linux::page_size())) {
4878 fatal("Could not disable polling page");
4879 }
4880 }
4881
4882 // Mark the polling page as readable
4883 void os::make_polling_page_readable(void) {
4884 if (!linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) {
4885 fatal("Could not enable polling page");
4886 }
4887 }
4888
4889 int os::active_processor_count() {
4890 // Linux doesn't yet have a (official) notion of processor sets,
4891 // so just return the number of online processors.
4892 int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN);
4893 assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check");
4894 return online_cpus;
4895 }
4896
4897 void os::set_native_thread_name(const char *name) {
4898 // Not yet implemented.
4899 return;
4900 }
4901
4902 bool os::distribute_processes(uint length, uint* distribution) {
4903 // Not yet implemented.
4904 return false;
4905 }
4906
4907 bool os::bind_to_processor(uint processor_id) {
4908 // Not yet implemented.
4909 return false;
4910 }
4911
4912 ///
4913
4914 void os::SuspendedThreadTask::internal_do_task() {
4915 if (do_suspend(_thread->osthread())) {
4916 SuspendedThreadTaskContext context(_thread, _thread->osthread()->ucontext());
4917 do_task(context);
4918 do_resume(_thread->osthread());
4919 }
4920 }
4921
4922 class PcFetcher : public os::SuspendedThreadTask {
4923 public:
4924 PcFetcher(Thread* thread) : os::SuspendedThreadTask(thread) {}
4925 ExtendedPC result();
4926 protected:
4927 void do_task(const os::SuspendedThreadTaskContext& context);
4928 private:
4929 ExtendedPC _epc;
4930 };
4931
4932 ExtendedPC PcFetcher::result() {
4933 guarantee(is_done(), "task is not done yet.");
4934 return _epc;
4935 }
4936
4937 void PcFetcher::do_task(const os::SuspendedThreadTaskContext& context) {
4938 Thread* thread = context.thread();
4939 OSThread* osthread = thread->osthread();
4940 if (osthread->ucontext() != NULL) {
4941 _epc = os::Linux::ucontext_get_pc((ucontext_t *) context.ucontext());
4942 } else {
4943 // NULL context is unexpected, double-check this is the VMThread
4944 guarantee(thread->is_VM_thread(), "can only be called for VMThread");
4945 }
4946 }
4947
4948 // Suspends the target using the signal mechanism and then grabs the PC before
4949 // resuming the target. Used by the flat-profiler only
4950 ExtendedPC os::get_thread_pc(Thread* thread) {
4951 // Make sure that it is called by the watcher for the VMThread
4952 assert(Thread::current()->is_Watcher_thread(), "Must be watcher");
4953 assert(thread->is_VM_thread(), "Can only be called for VMThread");
4954
4955 PcFetcher fetcher(thread);
4956 fetcher.run();
4957 return fetcher.result();
4958 }
4959
4960 int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond,
4961 pthread_mutex_t *_mutex,
4962 const struct timespec *_abstime) {
4963 if (is_NPTL()) {
4964 return pthread_cond_timedwait(_cond, _mutex, _abstime);
4965 } else {
4966 // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control
4967 // word back to default 64bit precision if condvar is signaled. Java
4968 // wants 53bit precision. Save and restore current value.
4969 int fpu = get_fpu_control_word();
4970 int status = pthread_cond_timedwait(_cond, _mutex, _abstime);
4971 set_fpu_control_word(fpu);
4972 return status;
4973 }
4974 }
4975
4976 ////////////////////////////////////////////////////////////////////////////////
4977 // debug support
4978
4979 bool os::find(address addr, outputStream* st) {
4980 Dl_info dlinfo;
4981 memset(&dlinfo, 0, sizeof(dlinfo));
4982 if (dladdr(addr, &dlinfo) != 0) {
4983 st->print(PTR_FORMAT ": ", addr);
4984 if (dlinfo.dli_sname != NULL && dlinfo.dli_saddr != NULL) {
4985 st->print("%s+%#x", dlinfo.dli_sname,
4986 addr - (intptr_t)dlinfo.dli_saddr);
4987 } else if (dlinfo.dli_fbase != NULL) {
4988 st->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase);
4989 } else {
4990 st->print("<absolute address>");
4991 }
4992 if (dlinfo.dli_fname != NULL) {
4993 st->print(" in %s", dlinfo.dli_fname);
4994 }
4995 if (dlinfo.dli_fbase != NULL) {
4996 st->print(" at " PTR_FORMAT, dlinfo.dli_fbase);
4997 }
4998 st->cr();
4999
5000 if (Verbose) {
5001 // decode some bytes around the PC
5002 address begin = clamp_address_in_page(addr-40, addr, os::vm_page_size());
5003 address end = clamp_address_in_page(addr+40, addr, os::vm_page_size());
5004 address lowest = (address) dlinfo.dli_sname;
5005 if (!lowest) lowest = (address) dlinfo.dli_fbase;
5006 if (begin < lowest) begin = lowest;
5007 Dl_info dlinfo2;
5008 if (dladdr(end, &dlinfo2) != 0 && dlinfo2.dli_saddr != dlinfo.dli_saddr
5009 && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin) {
5010 end = (address) dlinfo2.dli_saddr;
5011 }
5012 Disassembler::decode(begin, end, st);
5013 }
5014 return true;
5015 }
5016 return false;
5017 }
5018
5019 ////////////////////////////////////////////////////////////////////////////////
5020 // misc
5021
5022 // This does not do anything on Linux. This is basically a hook for being
5023 // able to use structured exception handling (thread-local exception filters)
5024 // on, e.g., Win32.
5025 void
5026 os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method,
5027 JavaCallArguments* args, Thread* thread) {
5028 f(value, method, args, thread);
5029 }
5030
5031 void os::print_statistics() {
5032 }
5033
5034 int os::message_box(const char* title, const char* message) {
5035 int i;
5036 fdStream err(defaultStream::error_fd());
5037 for (i = 0; i < 78; i++) err.print_raw("=");
5038 err.cr();
5039 err.print_raw_cr(title);
5040 for (i = 0; i < 78; i++) err.print_raw("-");
5041 err.cr();
5042 err.print_raw_cr(message);
5043 for (i = 0; i < 78; i++) err.print_raw("=");
5044 err.cr();
5045
5046 char buf[16];
5047 // Prevent process from exiting upon "read error" without consuming all CPU
5048 while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); }
5049
5050 return buf[0] == 'y' || buf[0] == 'Y';
5051 }
5052
5053 int os::stat(const char *path, struct stat *sbuf) {
5054 char pathbuf[MAX_PATH];
5055 if (strlen(path) > MAX_PATH - 1) {
5056 errno = ENAMETOOLONG;
5057 return -1;
5058 }
5059 os::native_path(strcpy(pathbuf, path));
5060 return ::stat(pathbuf, sbuf);
5061 }
5062
5063 bool os::check_heap(bool force) {
5064 return true;
5065 }
5066
5067 // Is a (classpath) directory empty?
5068 bool os::dir_is_empty(const char* path) {
5069 DIR *dir = NULL;
5070 struct dirent *ptr;
5071
5072 dir = opendir(path);
5073 if (dir == NULL) return true;
5074
5075 // Scan the directory
5076 bool result = true;
5077 char buf[sizeof(struct dirent) + MAX_PATH];
5078 while (result && (ptr = ::readdir(dir)) != NULL) {
5079 if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) {
5080 result = false;
5081 }
5082 }
5083 closedir(dir);
5084 return result;
5085 }
5086
5087 // This code originates from JDK's sysOpen and open64_w
5088 // from src/solaris/hpi/src/system_md.c
5089
5090 #ifndef O_DELETE
5091 #define O_DELETE 0x10000
5092 #endif
5093
5094 // Open a file. Unlink the file immediately after open returns
5095 // if the specified oflag has the O_DELETE flag set.
5096 // O_DELETE is used only in j2se/src/share/native/java/util/zip/ZipFile.c
5097
5098 int os::open(const char *path, int oflag, int mode) {
5099 if (strlen(path) > MAX_PATH - 1) {
5100 errno = ENAMETOOLONG;
5101 return -1;
5102 }
5103 int fd;
5104 int o_delete = (oflag & O_DELETE);
5105 oflag = oflag & ~O_DELETE;
5106
5107 fd = ::open64(path, oflag, mode);
5108 if (fd == -1) return -1;
5109
5110 //If the open succeeded, the file might still be a directory
5111 {
5112 struct stat64 buf64;
5113 int ret = ::fstat64(fd, &buf64);
5114 int st_mode = buf64.st_mode;
5115
5116 if (ret != -1) {
5117 if ((st_mode & S_IFMT) == S_IFDIR) {
5118 errno = EISDIR;
5119 ::close(fd);
5120 return -1;
5121 }
5122 } else {
5123 ::close(fd);
5124 return -1;
5125 }
5126 }
5127
5128 // All file descriptors that are opened in the JVM and not
5129 // specifically destined for a subprocess should have the
5130 // close-on-exec flag set. If we don't set it, then careless 3rd
5131 // party native code might fork and exec without closing all
5132 // appropriate file descriptors (e.g. as we do in closeDescriptors in
5133 // UNIXProcess.c), and this in turn might:
5134 //
5135 // - cause end-of-file to fail to be detected on some file
5136 // descriptors, resulting in mysterious hangs, or
5137 //
5138 // - might cause an fopen in the subprocess to fail on a system
5139 // suffering from bug 1085341.
5140 //
5141 // (Yes, the default setting of the close-on-exec flag is a Unix
5142 // design flaw)
5143 //
5144 // See:
5145 // 1085341: 32-bit stdio routines should support file descriptors >255
5146 // 4843136: (process) pipe file descriptor from Runtime.exec not being closed
5147 // 6339493: (process) Runtime.exec does not close all file descriptors on Solaris 9
5148 //
5149 #ifdef FD_CLOEXEC
5150 {
5151 int flags = ::fcntl(fd, F_GETFD);
5152 if (flags != -1) {
5153 ::fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
5154 }
5155 }
5156 #endif
5157
5158 if (o_delete != 0) {
5159 ::unlink(path);
5160 }
5161 return fd;
5162 }
5163
5164
5165 // create binary file, rewriting existing file if required
5166 int os::create_binary_file(const char* path, bool rewrite_existing) {
5167 int oflags = O_WRONLY | O_CREAT;
5168 if (!rewrite_existing) {
5169 oflags |= O_EXCL;
5170 }
5171 return ::open64(path, oflags, S_IREAD | S_IWRITE);
5172 }
5173
5174 // return current position of file pointer
5175 jlong os::current_file_offset(int fd) {
5176 return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR);
5177 }
5178
5179 // move file pointer to the specified offset
5180 jlong os::seek_to_file_offset(int fd, jlong offset) {
5181 return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET);
5182 }
5183
5184 // This code originates from JDK's sysAvailable
5185 // from src/solaris/hpi/src/native_threads/src/sys_api_td.c
5186
5187 int os::available(int fd, jlong *bytes) {
5188 jlong cur, end;
5189 int mode;
5190 struct stat64 buf64;
5191
5192 if (::fstat64(fd, &buf64) >= 0) {
5193 mode = buf64.st_mode;
5194 if (S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) {
5195 // XXX: is the following call interruptible? If so, this might
5196 // need to go through the INTERRUPT_IO() wrapper as for other
5197 // blocking, interruptible calls in this file.
5198 int n;
5199 if (::ioctl(fd, FIONREAD, &n) >= 0) {
5200 *bytes = n;
5201 return 1;
5202 }
5203 }
5204 }
5205 if ((cur = ::lseek64(fd, 0L, SEEK_CUR)) == -1) {
5206 return 0;
5207 } else if ((end = ::lseek64(fd, 0L, SEEK_END)) == -1) {
5208 return 0;
5209 } else if (::lseek64(fd, cur, SEEK_SET) == -1) {
5210 return 0;
5211 }
5212 *bytes = end - cur;
5213 return 1;
5214 }
5215
5216 int os::socket_available(int fd, jint *pbytes) {
5217 // Linux doc says EINTR not returned, unlike Solaris
5218 int ret = ::ioctl(fd, FIONREAD, pbytes);
5219
5220 //%% note ioctl can return 0 when successful, JVM_SocketAvailable
5221 // is expected to return 0 on failure and 1 on success to the jdk.
5222 return (ret < 0) ? 0 : 1;
5223 }
5224
5225 // Map a block of memory.
5226 char* os::pd_map_memory(int fd, const char* file_name, size_t file_offset,
5227 char *addr, size_t bytes, bool read_only,
5228 bool allow_exec) {
5229 int prot;
5230 int flags = MAP_PRIVATE;
5231
5232 if (read_only) {
5233 prot = PROT_READ;
5234 } else {
5235 prot = PROT_READ | PROT_WRITE;
5236 }
5237
5238 if (allow_exec) {
5239 prot |= PROT_EXEC;
5240 }
5241
5242 if (addr != NULL) {
5243 flags |= MAP_FIXED;
5244 }
5245
5246 char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags,
5247 fd, file_offset);
5248 if (mapped_address == MAP_FAILED) {
5249 return NULL;
5250 }
5251 return mapped_address;
5252 }
5253
5254
5255 // Remap a block of memory.
5256 char* os::pd_remap_memory(int fd, const char* file_name, size_t file_offset,
5257 char *addr, size_t bytes, bool read_only,
5258 bool allow_exec) {
5259 // same as map_memory() on this OS
5260 return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only,
5261 allow_exec);
5262 }
5263
5264
5265 // Unmap a block of memory.
5266 bool os::pd_unmap_memory(char* addr, size_t bytes) {
5267 return munmap(addr, bytes) == 0;
5268 }
5269
5270 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time);
5271
5272 static clockid_t thread_cpu_clockid(Thread* thread) {
5273 pthread_t tid = thread->osthread()->pthread_id();
5274 clockid_t clockid;
5275
5276 // Get thread clockid
5277 int rc = os::Linux::pthread_getcpuclockid(tid, &clockid);
5278 assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code");
5279 return clockid;
5280 }
5281
5282 // current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool)
5283 // are used by JVM M&M and JVMTI to get user+sys or user CPU time
5284 // of a thread.
5285 //
5286 // current_thread_cpu_time() and thread_cpu_time(Thread*) returns
5287 // the fast estimate available on the platform.
5288
5289 jlong os::current_thread_cpu_time() {
5290 if (os::Linux::supports_fast_thread_cpu_time()) {
5291 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
5292 } else {
5293 // return user + sys since the cost is the same
5294 return slow_thread_cpu_time(Thread::current(), true /* user + sys */);
5295 }
5296 }
5297
5298 jlong os::thread_cpu_time(Thread* thread) {
5299 // consistent with what current_thread_cpu_time() returns
5300 if (os::Linux::supports_fast_thread_cpu_time()) {
5301 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread));
5302 } else {
5303 return slow_thread_cpu_time(thread, true /* user + sys */);
5304 }
5305 }
5306
5307 jlong os::current_thread_cpu_time(bool user_sys_cpu_time) {
5308 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
5309 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
5310 } else {
5311 return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time);
5312 }
5313 }
5314
5315 jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
5316 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
5317 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread));
5318 } else {
5319 return slow_thread_cpu_time(thread, user_sys_cpu_time);
5320 }
5321 }
5322
5323 // -1 on error.
5324 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
5325 pid_t tid = thread->osthread()->thread_id();
5326 char *s;
5327 char stat[2048];
5328 int statlen;
5329 char proc_name[64];
5330 int count;
5331 long sys_time, user_time;
5332 char cdummy;
5333 int idummy;
5334 long ldummy;
5335 FILE *fp;
5336
5337 snprintf(proc_name, 64, "/proc/self/task/%d/stat", tid);
5338 fp = fopen(proc_name, "r");
5339 if (fp == NULL) return -1;
5340 statlen = fread(stat, 1, 2047, fp);
5341 stat[statlen] = '\0';
5342 fclose(fp);
5343
5344 // Skip pid and the command string. Note that we could be dealing with
5345 // weird command names, e.g. user could decide to rename java launcher
5346 // to "java 1.4.2 :)", then the stat file would look like
5347 // 1234 (java 1.4.2 :)) R ... ...
5348 // We don't really need to know the command string, just find the last
5349 // occurrence of ")" and then start parsing from there. See bug 4726580.
5350 s = strrchr(stat, ')');
5351 if (s == NULL) return -1;
5352
5353 // Skip blank chars
5354 do s++; while (isspace(*s));
5355
5356 count = sscanf(s,"%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu",
5357 &cdummy, &idummy, &idummy, &idummy, &idummy, &idummy,
5358 &ldummy, &ldummy, &ldummy, &ldummy, &ldummy,
5359 &user_time, &sys_time);
5360 if (count != 13) return -1;
5361 if (user_sys_cpu_time) {
5362 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec);
5363 } else {
5364 return (jlong)user_time * (1000000000 / clock_tics_per_sec);
5365 }
5366 }
5367
5368 void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
5369 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits
5370 info_ptr->may_skip_backward = false; // elapsed time not wall time
5371 info_ptr->may_skip_forward = false; // elapsed time not wall time
5372 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned
5373 }
5374
5375 void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
5376 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits
5377 info_ptr->may_skip_backward = false; // elapsed time not wall time
5378 info_ptr->may_skip_forward = false; // elapsed time not wall time
5379 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned
5380 }
5381
5382 bool os::is_thread_cpu_time_supported() {
5383 return true;
5384 }
5385
5386 // System loadavg support. Returns -1 if load average cannot be obtained.
5387 // Linux doesn't yet have a (official) notion of processor sets,
5388 // so just return the system wide load average.
5389 int os::loadavg(double loadavg[], int nelem) {
5390 return ::getloadavg(loadavg, nelem);
5391 }
5392
5393 void os::pause() {
5394 char filename[MAX_PATH];
5395 if (PauseAtStartupFile && PauseAtStartupFile[0]) {
5396 jio_snprintf(filename, MAX_PATH, PauseAtStartupFile);
5397 } else {
5398 jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id());
5399 }
5400
5401 int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
5402 if (fd != -1) {
5403 struct stat buf;
5404 ::close(fd);
5405 while (::stat(filename, &buf) == 0) {
5406 (void)::poll(NULL, 0, 100);
5407 }
5408 } else {
5409 jio_fprintf(stderr,
5410 "Could not open pause file '%s', continuing immediately.\n", filename);
5411 }
5412 }
5413
5414
5415 // Refer to the comments in os_solaris.cpp park-unpark.
5416 //
5417 // Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can
5418 // hang indefinitely. For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable.
5419 // For specifics regarding the bug see GLIBC BUGID 261237 :
5420 // http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html.
5421 // Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future
5422 // will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar
5423 // is used. (The simple C test-case provided in the GLIBC bug report manifests the
5424 // hang). The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos()
5425 // and monitorenter when we're using 1-0 locking. All those operations may result in
5426 // calls to pthread_cond_timedwait(). Using LD_ASSUME_KERNEL to use an older version
5427 // of libpthread avoids the problem, but isn't practical.
5428 //
5429 // Possible remedies:
5430 //
5431 // 1. Establish a minimum relative wait time. 50 to 100 msecs seems to work.
5432 // This is palliative and probabilistic, however. If the thread is preempted
5433 // between the call to compute_abstime() and pthread_cond_timedwait(), more
5434 // than the minimum period may have passed, and the abstime may be stale (in the
5435 // past) resultin in a hang. Using this technique reduces the odds of a hang
5436 // but the JVM is still vulnerable, particularly on heavily loaded systems.
5437 //
5438 // 2. Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead
5439 // of the usual flag-condvar-mutex idiom. The write side of the pipe is set
5440 // NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo)
5441 // reduces to poll()+read(). This works well, but consumes 2 FDs per extant
5442 // thread.
5443 //
5444 // 3. Embargo pthread_cond_timedwait() and implement a native "chron" thread
5445 // that manages timeouts. We'd emulate pthread_cond_timedwait() by enqueuing
5446 // a timeout request to the chron thread and then blocking via pthread_cond_wait().
5447 // This also works well. In fact it avoids kernel-level scalability impediments
5448 // on certain platforms that don't handle lots of active pthread_cond_timedwait()
5449 // timers in a graceful fashion.
5450 //
5451 // 4. When the abstime value is in the past it appears that control returns
5452 // correctly from pthread_cond_timedwait(), but the condvar is left corrupt.
5453 // Subsequent timedwait/wait calls may hang indefinitely. Given that, we
5454 // can avoid the problem by reinitializing the condvar -- by cond_destroy()
5455 // followed by cond_init() -- after all calls to pthread_cond_timedwait().
5456 // It may be possible to avoid reinitialization by checking the return
5457 // value from pthread_cond_timedwait(). In addition to reinitializing the
5458 // condvar we must establish the invariant that cond_signal() is only called
5459 // within critical sections protected by the adjunct mutex. This prevents
5460 // cond_signal() from "seeing" a condvar that's in the midst of being
5461 // reinitialized or that is corrupt. Sadly, this invariant obviates the
5462 // desirable signal-after-unlock optimization that avoids futile context switching.
5463 //
5464 // I'm also concerned that some versions of NTPL might allocate an auxilliary
5465 // structure when a condvar is used or initialized. cond_destroy() would
5466 // release the helper structure. Our reinitialize-after-timedwait fix
5467 // put excessive stress on malloc/free and locks protecting the c-heap.
5468 //
5469 // We currently use (4). See the WorkAroundNTPLTimedWaitHang flag.
5470 // It may be possible to refine (4) by checking the kernel and NTPL verisons
5471 // and only enabling the work-around for vulnerable environments.
5472
5473 // utility to compute the abstime argument to timedwait:
5474 // millis is the relative timeout time
5475 // abstime will be the absolute timeout time
5476 // TODO: replace compute_abstime() with unpackTime()
5477
5478 static struct timespec* compute_abstime(timespec* abstime, jlong millis) {
5479 if (millis < 0) millis = 0;
5480
5481 jlong seconds = millis / 1000;
5482 millis %= 1000;
5483 if (seconds > 50000000) { // see man cond_timedwait(3T)
5484 seconds = 50000000;
5485 }
5486
5487 if (os::supports_monotonic_clock()) {
5488 struct timespec now;
5489 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now);
5490 assert_status(status == 0, status, "clock_gettime");
5491 abstime->tv_sec = now.tv_sec + seconds;
5492 long nanos = now.tv_nsec + millis * NANOSECS_PER_MILLISEC;
5493 if (nanos >= NANOSECS_PER_SEC) {
5494 abstime->tv_sec += 1;
5495 nanos -= NANOSECS_PER_SEC;
5496 }
5497 abstime->tv_nsec = nanos;
5498 } else {
5499 struct timeval now;
5500 int status = gettimeofday(&now, NULL);
5501 assert(status == 0, "gettimeofday");
5502 abstime->tv_sec = now.tv_sec + seconds;
5503 long usec = now.tv_usec + millis * 1000;
5504 if (usec >= 1000000) {
5505 abstime->tv_sec += 1;
5506 usec -= 1000000;
5507 }
5508 abstime->tv_nsec = usec * 1000;
5509 }
5510 return abstime;
5511 }
5512
5513 void os::PlatformEvent::park() { // AKA "down()"
5514 // Invariant: Only the thread associated with the Event/PlatformEvent
5515 // may call park().
5516 // TODO: assert that _Assoc != NULL or _Assoc == Self
5517 assert(_nParked == 0, "invariant");
5518
5519 int v;
5520 for (;;) {
5521 v = _Event;
5522 if (Atomic::cmpxchg(v-1, &_Event, v) == v) break;
5523 }
5524 guarantee(v >= 0, "invariant");
5525 if (v == 0) {
5526 // Do this the hard way by blocking ...
5527 int status = pthread_mutex_lock(_mutex);
5528 assert_status(status == 0, status, "mutex_lock");
5529 guarantee(_nParked == 0, "invariant");
5530 ++_nParked;
5531 while (_Event < 0) {
5532 status = pthread_cond_wait(_cond, _mutex);
5533 // for some reason, under 2.7 lwp_cond_wait() may return ETIME ...
5534 // Treat this the same as if the wait was interrupted
5535 if (status == ETIME) { status = EINTR; }
5536 assert_status(status == 0 || status == EINTR, status, "cond_wait");
5537 }
5538 --_nParked;
5539
5540 _Event = 0;
5541 status = pthread_mutex_unlock(_mutex);
5542 assert_status(status == 0, status, "mutex_unlock");
5543 // Paranoia to ensure our locked and lock-free paths interact
5544 // correctly with each other.
5545 OrderAccess::fence();
5546 }
5547 guarantee(_Event >= 0, "invariant");
5548 }
5549
5550 int os::PlatformEvent::park(jlong millis) {
5551 guarantee(_nParked == 0, "invariant");
5552
5553 int v;
5554 for (;;) {
5555 v = _Event;
5556 if (Atomic::cmpxchg(v-1, &_Event, v) == v) break;
5557 }
5558 guarantee(v >= 0, "invariant");
5559 if (v != 0) return OS_OK;
5560
5561 // We do this the hard way, by blocking the thread.
5562 // Consider enforcing a minimum timeout value.
5563 struct timespec abst;
5564 compute_abstime(&abst, millis);
5565
5566 int ret = OS_TIMEOUT;
5567 int status = pthread_mutex_lock(_mutex);
5568 assert_status(status == 0, status, "mutex_lock");
5569 guarantee(_nParked == 0, "invariant");
5570 ++_nParked;
5571
5572 // Object.wait(timo) will return because of
5573 // (a) notification
5574 // (b) timeout
5575 // (c) thread.interrupt
5576 //
5577 // Thread.interrupt and object.notify{All} both call Event::set.
5578 // That is, we treat thread.interrupt as a special case of notification.
5579 // We ignore spurious OS wakeups unless FilterSpuriousWakeups is false.
5580 // We assume all ETIME returns are valid.
5581 //
5582 // TODO: properly differentiate simultaneous notify+interrupt.
5583 // In that case, we should propagate the notify to another waiter.
5584
5585 while (_Event < 0) {
5586 status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst);
5587 if (status != 0 && WorkAroundNPTLTimedWaitHang) {
5588 pthread_cond_destroy(_cond);
5589 pthread_cond_init(_cond, os::Linux::condAttr());
5590 }
5591 assert_status(status == 0 || status == EINTR ||
5592 status == ETIME || status == ETIMEDOUT,
5593 status, "cond_timedwait");
5594 if (!FilterSpuriousWakeups) break; // previous semantics
5595 if (status == ETIME || status == ETIMEDOUT) break;
5596 // We consume and ignore EINTR and spurious wakeups.
5597 }
5598 --_nParked;
5599 if (_Event >= 0) {
5600 ret = OS_OK;
5601 }
5602 _Event = 0;
5603 status = pthread_mutex_unlock(_mutex);
5604 assert_status(status == 0, status, "mutex_unlock");
5605 assert(_nParked == 0, "invariant");
5606 // Paranoia to ensure our locked and lock-free paths interact
5607 // correctly with each other.
5608 OrderAccess::fence();
5609 return ret;
5610 }
5611
5612 void os::PlatformEvent::unpark() {
5613 // Transitions for _Event:
5614 // 0 :=> 1
5615 // 1 :=> 1
5616 // -1 :=> either 0 or 1; must signal target thread
5617 // That is, we can safely transition _Event from -1 to either
5618 // 0 or 1.
5619 // See also: "Semaphores in Plan 9" by Mullender & Cox
5620 //
5621 // Note: Forcing a transition from "-1" to "1" on an unpark() means
5622 // that it will take two back-to-back park() calls for the owning
5623 // thread to block. This has the benefit of forcing a spurious return
5624 // from the first park() call after an unpark() call which will help
5625 // shake out uses of park() and unpark() without condition variables.
5626
5627 if (Atomic::xchg(1, &_Event) >= 0) return;
5628
5629 // Wait for the thread associated with the event to vacate
5630 int status = pthread_mutex_lock(_mutex);
5631 assert_status(status == 0, status, "mutex_lock");
5632 int AnyWaiters = _nParked;
5633 assert(AnyWaiters == 0 || AnyWaiters == 1, "invariant");
5634 if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) {
5635 AnyWaiters = 0;
5636 pthread_cond_signal(_cond);
5637 }
5638 status = pthread_mutex_unlock(_mutex);
5639 assert_status(status == 0, status, "mutex_unlock");
5640 if (AnyWaiters != 0) {
5641 status = pthread_cond_signal(_cond);
5642 assert_status(status == 0, status, "cond_signal");
5643 }
5644
5645 // Note that we signal() _after dropping the lock for "immortal" Events.
5646 // This is safe and avoids a common class of futile wakeups. In rare
5647 // circumstances this can cause a thread to return prematurely from
5648 // cond_{timed}wait() but the spurious wakeup is benign and the victim will
5649 // simply re-test the condition and re-park itself.
5650 }
5651
5652
5653 // JSR166
5654 // -------------------------------------------------------
5655
5656 // The solaris and linux implementations of park/unpark are fairly
5657 // conservative for now, but can be improved. They currently use a
5658 // mutex/condvar pair, plus a a count.
5659 // Park decrements count if > 0, else does a condvar wait. Unpark
5660 // sets count to 1 and signals condvar. Only one thread ever waits
5661 // on the condvar. Contention seen when trying to park implies that someone
5662 // is unparking you, so don't wait. And spurious returns are fine, so there
5663 // is no need to track notifications.
5664
5665 // This code is common to linux and solaris and will be moved to a
5666 // common place in dolphin.
5667 //
5668 // The passed in time value is either a relative time in nanoseconds
5669 // or an absolute time in milliseconds. Either way it has to be unpacked
5670 // into suitable seconds and nanoseconds components and stored in the
5671 // given timespec structure.
5672 // Given time is a 64-bit value and the time_t used in the timespec is only
5673 // a signed-32-bit value (except on 64-bit Linux) we have to watch for
5674 // overflow if times way in the future are given. Further on Solaris versions
5675 // prior to 10 there is a restriction (see cond_timedwait) that the specified
5676 // number of seconds, in abstime, is less than current_time + 100,000,000.
5677 // As it will be 28 years before "now + 100000000" will overflow we can
5678 // ignore overflow and just impose a hard-limit on seconds using the value
5679 // of "now + 100,000,000". This places a limit on the timeout of about 3.17
5680 // years from "now".
5681
5682 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) {
5683 assert(time > 0, "convertTime");
5684 time_t max_secs = 0;
5685
5686 if (!os::supports_monotonic_clock() || isAbsolute) {
5687 struct timeval now;
5688 int status = gettimeofday(&now, NULL);
5689 assert(status == 0, "gettimeofday");
5690
5691 max_secs = now.tv_sec + MAX_SECS;
5692
5693 if (isAbsolute) {
5694 jlong secs = time / 1000;
5695 if (secs > max_secs) {
5696 absTime->tv_sec = max_secs;
5697 } else {
5698 absTime->tv_sec = secs;
5699 }
5700 absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC;
5701 } else {
5702 jlong secs = time / NANOSECS_PER_SEC;
5703 if (secs >= MAX_SECS) {
5704 absTime->tv_sec = max_secs;
5705 absTime->tv_nsec = 0;
5706 } else {
5707 absTime->tv_sec = now.tv_sec + secs;
5708 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000;
5709 if (absTime->tv_nsec >= NANOSECS_PER_SEC) {
5710 absTime->tv_nsec -= NANOSECS_PER_SEC;
5711 ++absTime->tv_sec; // note: this must be <= max_secs
5712 }
5713 }
5714 }
5715 } else {
5716 // must be relative using monotonic clock
5717 struct timespec now;
5718 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now);
5719 assert_status(status == 0, status, "clock_gettime");
5720 max_secs = now.tv_sec + MAX_SECS;
5721 jlong secs = time / NANOSECS_PER_SEC;
5722 if (secs >= MAX_SECS) {
5723 absTime->tv_sec = max_secs;
5724 absTime->tv_nsec = 0;
5725 } else {
5726 absTime->tv_sec = now.tv_sec + secs;
5727 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_nsec;
5728 if (absTime->tv_nsec >= NANOSECS_PER_SEC) {
5729 absTime->tv_nsec -= NANOSECS_PER_SEC;
5730 ++absTime->tv_sec; // note: this must be <= max_secs
5731 }
5732 }
5733 }
5734 assert(absTime->tv_sec >= 0, "tv_sec < 0");
5735 assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs");
5736 assert(absTime->tv_nsec >= 0, "tv_nsec < 0");
5737 assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec");
5738 }
5739
5740 void Parker::park(bool isAbsolute, jlong time) {
5741 // Ideally we'd do something useful while spinning, such
5742 // as calling unpackTime().
5743
5744 // Optional fast-path check:
5745 // Return immediately if a permit is available.
5746 // We depend on Atomic::xchg() having full barrier semantics
5747 // since we are doing a lock-free update to _counter.
5748 if (Atomic::xchg(0, &_counter) > 0) return;
5749
5750 Thread* thread = Thread::current();
5751 assert(thread->is_Java_thread(), "Must be JavaThread");
5752 JavaThread *jt = (JavaThread *)thread;
5753
5754 // Optional optimization -- avoid state transitions if there's an interrupt pending.
5755 // Check interrupt before trying to wait
5756 if (Thread::is_interrupted(thread, false)) {
5757 return;
5758 }
5759
5760 // Next, demultiplex/decode time arguments
5761 timespec absTime;
5762 if (time < 0 || (isAbsolute && time == 0)) { // don't wait at all
5763 return;
5764 }
5765 if (time > 0) {
5766 unpackTime(&absTime, isAbsolute, time);
5767 }
5768
5769
5770 // Enter safepoint region
5771 // Beware of deadlocks such as 6317397.
5772 // The per-thread Parker:: mutex is a classic leaf-lock.
5773 // In particular a thread must never block on the Threads_lock while
5774 // holding the Parker:: mutex. If safepoints are pending both the
5775 // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock.
5776 ThreadBlockInVM tbivm(jt);
5777
5778 // Don't wait if cannot get lock since interference arises from
5779 // unblocking. Also. check interrupt before trying wait
5780 if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) {
5781 return;
5782 }
5783
5784 int status;
5785 if (_counter > 0) { // no wait needed
5786 _counter = 0;
5787 status = pthread_mutex_unlock(_mutex);
5788 assert(status == 0, "invariant");
5789 // Paranoia to ensure our locked and lock-free paths interact
5790 // correctly with each other and Java-level accesses.
5791 OrderAccess::fence();
5792 return;
5793 }
5794
5795 #ifdef ASSERT
5796 // Don't catch signals while blocked; let the running threads have the signals.
5797 // (This allows a debugger to break into the running thread.)
5798 sigset_t oldsigs;
5799 sigset_t* allowdebug_blocked = os::Linux::allowdebug_blocked_signals();
5800 pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs);
5801 #endif
5802
5803 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */);
5804 jt->set_suspend_equivalent();
5805 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
5806
5807 assert(_cur_index == -1, "invariant");
5808 if (time == 0) {
5809 _cur_index = REL_INDEX; // arbitrary choice when not timed
5810 status = pthread_cond_wait(&_cond[_cur_index], _mutex);
5811 } else {
5812 _cur_index = isAbsolute ? ABS_INDEX : REL_INDEX;
5813 status = os::Linux::safe_cond_timedwait(&_cond[_cur_index], _mutex, &absTime);
5814 if (status != 0 && WorkAroundNPTLTimedWaitHang) {
5815 pthread_cond_destroy(&_cond[_cur_index]);
5816 pthread_cond_init(&_cond[_cur_index], isAbsolute ? NULL : os::Linux::condAttr());
5817 }
5818 }
5819 _cur_index = -1;
5820 assert_status(status == 0 || status == EINTR ||
5821 status == ETIME || status == ETIMEDOUT,
5822 status, "cond_timedwait");
5823
5824 #ifdef ASSERT
5825 pthread_sigmask(SIG_SETMASK, &oldsigs, NULL);
5826 #endif
5827
5828 _counter = 0;
5829 status = pthread_mutex_unlock(_mutex);
5830 assert_status(status == 0, status, "invariant");
5831 // Paranoia to ensure our locked and lock-free paths interact
5832 // correctly with each other and Java-level accesses.
5833 OrderAccess::fence();
5834
5835 // If externally suspended while waiting, re-suspend
5836 if (jt->handle_special_suspend_equivalent_condition()) {
5837 jt->java_suspend_self();
5838 }
5839 }
5840
5841 void Parker::unpark() {
5842 int status = pthread_mutex_lock(_mutex);
5843 assert(status == 0, "invariant");
5844 const int s = _counter;
5845 _counter = 1;
5846 if (s < 1) {
5847 // thread might be parked
5848 if (_cur_index != -1) {
5849 // thread is definitely parked
5850 if (WorkAroundNPTLTimedWaitHang) {
5851 status = pthread_cond_signal(&_cond[_cur_index]);
5852 assert(status == 0, "invariant");
5853 status = pthread_mutex_unlock(_mutex);
5854 assert(status == 0, "invariant");
5855 } else {
5856 status = pthread_mutex_unlock(_mutex);
5857 assert(status == 0, "invariant");
5858 status = pthread_cond_signal(&_cond[_cur_index]);
5859 assert(status == 0, "invariant");
5860 }
5861 } else {
5862 pthread_mutex_unlock(_mutex);
5863 assert(status == 0, "invariant");
5864 }
5865 } else {
5866 pthread_mutex_unlock(_mutex);
5867 assert(status == 0, "invariant");
5868 }
5869 }
5870
5871
5872 extern char** environ;
5873
5874 #ifndef __NR_fork
5875 #define __NR_fork IA32_ONLY(2) IA64_ONLY(not defined) AMD64_ONLY(57)
5876 #endif
5877
5878 #ifndef __NR_execve
5879 #define __NR_execve IA32_ONLY(11) IA64_ONLY(1033) AMD64_ONLY(59)
5880 #endif
5881
5882 // Run the specified command in a separate process. Return its exit value,
5883 // or -1 on failure (e.g. can't fork a new process).
5884 // Unlike system(), this function can be called from signal handler. It
5885 // doesn't block SIGINT et al.
5886 int os::fork_and_exec(char* cmd) {
5887 const char * argv[4] = {"sh", "-c", cmd, NULL};
5888
5889 // fork() in LinuxThreads/NPTL is not async-safe. It needs to run
5890 // pthread_atfork handlers and reset pthread library. All we need is a
5891 // separate process to execve. Make a direct syscall to fork process.
5892 // On IA64 there's no fork syscall, we have to use fork() and hope for
5893 // the best...
5894 pid_t pid = NOT_IA64(syscall(__NR_fork);)
5895 IA64_ONLY(fork();)
5896
5897 if (pid < 0) {
5898 // fork failed
5899 return -1;
5900
5901 } else if (pid == 0) {
5902 // child process
5903
5904 // execve() in LinuxThreads will call pthread_kill_other_threads_np()
5905 // first to kill every thread on the thread list. Because this list is
5906 // not reset by fork() (see notes above), execve() will instead kill
5907 // every thread in the parent process. We know this is the only thread
5908 // in the new process, so make a system call directly.
5909 // IA64 should use normal execve() from glibc to match the glibc fork()
5910 // above.
5911 NOT_IA64(syscall(__NR_execve, "/bin/sh", argv, environ);)
5912 IA64_ONLY(execve("/bin/sh", (char* const*)argv, environ);)
5913
5914 // execve failed
5915 _exit(-1);
5916
5917 } else {
5918 // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't
5919 // care about the actual exit code, for now.
5920
5921 int status;
5922
5923 // Wait for the child process to exit. This returns immediately if
5924 // the child has already exited. */
5925 while (waitpid(pid, &status, 0) < 0) {
5926 switch (errno) {
5927 case ECHILD: return 0;
5928 case EINTR: break;
5929 default: return -1;
5930 }
5931 }
5932
5933 if (WIFEXITED(status)) {
5934 // The child exited normally; get its exit code.
5935 return WEXITSTATUS(status);
5936 } else if (WIFSIGNALED(status)) {
5937 // The child exited because of a signal
5938 // The best value to return is 0x80 + signal number,
5939 // because that is what all Unix shells do, and because
5940 // it allows callers to distinguish between process exit and
5941 // process death by signal.
5942 return 0x80 + WTERMSIG(status);
5943 } else {
5944 // Unknown exit code; pass it through
5945 return status;
5946 }
5947 }
5948 }
5949
5950 // is_headless_jre()
5951 //
5952 // Test for the existence of xawt/libmawt.so or libawt_xawt.so
5953 // in order to report if we are running in a headless jre
5954 //
5955 // Since JDK8 xawt/libmawt.so was moved into the same directory
5956 // as libawt.so, and renamed libawt_xawt.so
5957 //
5958 bool os::is_headless_jre() {
5959 struct stat statbuf;
5960 char buf[MAXPATHLEN];
5961 char libmawtpath[MAXPATHLEN];
5962 const char *xawtstr = "/xawt/libmawt.so";
5963 const char *new_xawtstr = "/libawt_xawt.so";
5964 char *p;
5965
5966 // Get path to libjvm.so
5967 os::jvm_path(buf, sizeof(buf));
5968
5969 // Get rid of libjvm.so
5970 p = strrchr(buf, '/');
5971 if (p == NULL) {
5972 return false;
5973 } else {
5974 *p = '\0';
5975 }
5976
5977 // Get rid of client or server
5978 p = strrchr(buf, '/');
5979 if (p == NULL) {
5980 return false;
5981 } else {
5982 *p = '\0';
5983 }
5984
5985 // check xawt/libmawt.so
5986 strcpy(libmawtpath, buf);
5987 strcat(libmawtpath, xawtstr);
5988 if (::stat(libmawtpath, &statbuf) == 0) return false;
5989
5990 // check libawt_xawt.so
5991 strcpy(libmawtpath, buf);
5992 strcat(libmawtpath, new_xawtstr);
5993 if (::stat(libmawtpath, &statbuf) == 0) return false;
5994
5995 return true;
5996 }
5997
5998 // Get the default path to the core file
5999 // Returns the length of the string
6000 int os::get_core_path(char* buffer, size_t bufferSize) {
6001 /*
6002 * Max length of /proc/sys/kernel/core_pattern is 128 characters.
6003 * See https://www.kernel.org/doc/Documentation/sysctl/kernel.txt
6004 */
6005 const int core_pattern_len = 129;
6006 char core_pattern[core_pattern_len] = {0};
6007
6008 FILE *core_pattern_file = fopen("/proc/sys/kernel/core_pattern", "r");
6009 if (core_pattern_file != NULL) {
6010 char *ret_ptr = fgets(core_pattern, core_pattern_len, core_pattern_file);
6011 fclose(core_pattern_file);
6012
6013 if (ret_ptr != NULL) {
6014 char *last_char = core_pattern + strlen(core_pattern) - 1;
6015 if (*last_char == '\n') {
6016 *last_char = '\0';
6017 }
6018 }
6019
6020 }
6021
6022 if (strlen(core_pattern) == 0) {
6023 return 0;
6024 }
6025
6026 // Get executable path for 'e' and 'E'
6027 char exe_path[PATH_MAX] = {0};
6028 readlink("/proc/self/exe", exe_path, PATH_MAX);
6029
6030 char core_path[PATH_MAX] = {0};
6031 bool with_pid = false;
6032 size_t n = 0;
6033 char *core_pattern_seq = core_pattern;
6034 while (*core_pattern_seq) {
6035
6036 if (*core_pattern_seq == '%') {
6037 int written = 0;
6038 core_pattern_seq++; // Get format character
6039
6040 switch (*core_pattern_seq) {
6041
6042 case '\0': // NULL termination
6043 break;
6044
6045 case '%': // double percent
6046 written = jio_snprintf(&core_path[n], PATH_MAX - n, "%%");
6047 break;
6048
6049 case 'p': // pid
6050 with_pid = true;
6051 written = jio_snprintf(&core_path[n], PATH_MAX - n, "%d", current_process_id());
6052 break;
6053
6054 case 'u': // uid
6055 written = jio_snprintf(&core_path[n], PATH_MAX - n, "%d", getuid());
6056 break;
6057
6058 case 'g': // gid
6059 written = jio_snprintf(&core_path[n], PATH_MAX - n, "%d", getgid());
6060 break;
6061
6062 case 'd': // dump mode
6063 written = jio_snprintf(&core_path[n], PATH_MAX - n, "%d",
6064 prctl(PR_GET_DUMPABLE, NULL, NULL, NULL, NULL));
6065 break;
6066
6067 case 'h': // hostname
6068 struct utsname un;
6069 uname(&un); // This call will be succeeded.
6070 written = jio_snprintf(&core_path[n], PATH_MAX - n, "%s", un.nodename);
6071 break;
6072
6073 case 'e': // executable filename (shorten)
6074 written = jio_snprintf(&core_path[n], PATH_MAX - n, "%s", basename(exe_path));
6075 break;
6076
6077 case 'E': // executable filename (path)
6078 written = jio_snprintf(&core_path[n], PATH_MAX - n, "%s", exe_path);
6079 break;
6080
6081 case 'c': // core limit size
6082 struct rlimit rlim;
6083 getrlimit(RLIMIT_CORE, &rlim); // Calling getrlimit() to myself will be succeeded.
6084 written = jio_snprintf(&core_path[n], PATH_MAX - n, "%lu", rlim.rlim_cur);
6085 break;
6086
6087 /*
6088 * We cannot other values.
6089 * e.g. 'P' (global pid), 's' (signal), 't' (UNIX time of dump)
6090 *
6091 * - 't' will set to core dump time in Linux kernel.
6092 * Thus we cannot set it in this function.
6093 * - If user set undefined character, Linux kernel will drop it.
6094 * We remain it because Linux kernel may define it in the future.
6095 */
6096 default:
6097 written = jio_snprintf(&core_path[n], PATH_MAX - n, "%%%c", *core_pattern_seq);
6098 break;
6099
6100 }
6101
6102 n += written;
6103 } else {
6104 core_path[n] = *core_pattern_seq;
6105 n++;
6106 }
6107
6108 core_pattern_seq++; // Get next character
6109 }
6110
6111 if (!with_pid && (core_path[0] != '|')) {
6112 char val[2] = {0};
6113 FILE *core_uses_pid_file = fopen("/proc/sys/kernel/core_uses_pid", "r");
6114 if (core_uses_pid_file != NULL) {
6115 fgets(val, 2, core_uses_pid_file);
6116 fclose(core_uses_pid_file);
6117 }
6118
6119 if (val[0] == '1') {
6120 n += jio_snprintf(&core_path[n], PATH_MAX - n, ".%d", current_process_id());
6121 }
6122
6123 }
6124
6125 if (n > bufferSize) {
6126 n = bufferSize;
6127 }
6128
6129 if (core_path[0] == '/') {
6130 jio_snprintf(buffer, n, core_path);
6131 } else {
6132 char cwd[PATH_MAX];
6133 const char* p = get_current_directory(cwd, PATH_MAX);
6134
6135 if (p == NULL) {
6136 assert(p != NULL, "failed to get current directory");
6137 return 0;
6138 }
6139
6140 if (core_path[0] == '|') {
6141 jio_snprintf(buffer, bufferSize, "%s (or dumping to %s/core.%d)",
6142 core_path, p, current_process_id());
6143 } else {
6144 jio_snprintf(buffer, bufferSize, "%s/%s", p, core_path);
6145 }
6146
6147 }
6148
6149 return strlen(buffer);
6150 }
6151
6152 // Check core dump limit and report possible place where core can be found
6153 void os::check_or_create_dump(void* exceptionRecord, void* contextRecord, char* buffer, size_t bufferSize) {
6154 int n;
6155 bool success;
6156 char core_path[PATH_MAX];
6157
6158 n = get_core_path(core_path, PATH_MAX);
6159
6160 if (n == 0) {
6161 jio_snprintf(buffer, bufferSize, "/core or core.%d (may not exist)", current_process_id());
6162 success = true;
6163 } else if (core_path[0] == '|') {
6164 jio_snprintf(buffer, bufferSize, "Core dumps may be processed with \"%s\"", &core_path[1]);
6165 success = true;
6166 } else {
6167 struct rlimit rlim;
6168 getrlimit(RLIMIT_CORE, &rlim); // Calling getrlimit() to myself will be succeeded.
6169
6170 switch(rlim.rlim_cur) {
6171 case RLIM_INFINITY:
6172 jio_snprintf(buffer, bufferSize, "%s", core_path);
6173 success = true;
6174 break;
6175 case 0:
6176 jio_snprintf(buffer, bufferSize, "Core dumps have been disabled. To enable core dumping, try \"ulimit -c unlimited\" before starting Java again");
6177 success = false;
6178 break;
6179 default:
6180 jio_snprintf(buffer, bufferSize, "%s (max size %lu kB). To ensure a full core dump, try \"ulimit -c unlimited\" before starting Java again", core_path, (unsigned long)(rlim.rlim_cur >> 10));
6181 success = true;
6182 break;
6183 }
6184 }
6185 VMError::report_coredump_status(buffer, success);
6186 }
6187
6188
6189 #ifdef JAVASE_EMBEDDED
6190 //
6191 // A thread to watch the '/dev/mem_notify' device, which will tell us when the OS is running low on memory.
6192 //
6193 MemNotifyThread* MemNotifyThread::_memnotify_thread = NULL;
6194
6195 // ctor
6196 //
6197 MemNotifyThread::MemNotifyThread(int fd): Thread() {
6198 assert(memnotify_thread() == NULL, "we can only allocate one MemNotifyThread");
6199 _fd = fd;
6200
6201 if (os::create_thread(this, os::os_thread)) {
6202 _memnotify_thread = this;
6203 os::set_priority(this, NearMaxPriority);
6204 os::start_thread(this);
6205 }
6206 }
6207
6208 // Where all the work gets done
6209 //
6210 void MemNotifyThread::run() {
6211 assert(this == memnotify_thread(), "expected the singleton MemNotifyThread");
6212
6213 // Set up the select arguments
6214 fd_set rfds;
6215 if (_fd != -1) {
6216 FD_ZERO(&rfds);
6217 FD_SET(_fd, &rfds);
6218 }
6219
6220 // Now wait for the mem_notify device to wake up
6221 while (1) {
6222 // Wait for the mem_notify device to signal us..
6223 int rc = select(_fd+1, _fd != -1 ? &rfds : NULL, NULL, NULL, NULL);
6224 if (rc == -1) {
6225 perror("select!\n");
6226 break;
6227 } else if (rc) {
6228 //ssize_t free_before = os::available_memory();
6229 //tty->print ("Notified: Free: %dK \n",os::available_memory()/1024);
6230
6231 // The kernel is telling us there is not much memory left...
6232 // try to do something about that
6233
6234 // If we are not already in a GC, try one.
6235 if (!Universe::heap()->is_gc_active()) {
6236 Universe::heap()->collect(GCCause::_allocation_failure);
6237
6238 //ssize_t free_after = os::available_memory();
6239 //tty->print ("Post-Notify: Free: %dK\n",free_after/1024);
6240 //tty->print ("GC freed: %dK\n", (free_after - free_before)/1024);
6241 }
6242 // We might want to do something like the following if we find the GC's are not helping...
6243 // Universe::heap()->size_policy()->set_gc_time_limit_exceeded(true);
6244 }
6245 }
6246 }
6247
6248 // See if the /dev/mem_notify device exists, and if so, start a thread to monitor it.
6249 //
6250 void MemNotifyThread::start() {
6251 int fd;
6252 fd = open("/dev/mem_notify", O_RDONLY, 0);
6253 if (fd < 0) {
6254 return;
6255 }
6256
6257 if (memnotify_thread() == NULL) {
6258 new MemNotifyThread(fd);
6259 }
6260 }
6261
6262 #endif // JAVASE_EMBEDDED
6263
6264
6265 /////////////// Unit tests ///////////////
6266
6267 #ifndef PRODUCT
6268
6269 #define test_log(...) \
6270 do { \
6271 if (VerboseInternalVMTests) { \
6272 tty->print_cr(__VA_ARGS__); \
6273 tty->flush(); \
6274 } \
6275 } while (false)
6276
6277 class TestReserveMemorySpecial : AllStatic {
6278 public:
6279 static void small_page_write(void* addr, size_t size) {
6280 size_t page_size = os::vm_page_size();
6281
6282 char* end = (char*)addr + size;
6283 for (char* p = (char*)addr; p < end; p += page_size) {
6284 *p = 1;
6285 }
6286 }
6287
6288 static void test_reserve_memory_special_huge_tlbfs_only(size_t size) {
6289 if (!UseHugeTLBFS) {
6290 return;
6291 }
6292
6293 test_log("test_reserve_memory_special_huge_tlbfs_only(" SIZE_FORMAT ")", size);
6294
6295 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_only(size, NULL, false);
6296
6297 if (addr != NULL) {
6298 small_page_write(addr, size);
6299
6300 os::Linux::release_memory_special_huge_tlbfs(addr, size);
6301 }
6302 }
6303
6304 static void test_reserve_memory_special_huge_tlbfs_only() {
6305 if (!UseHugeTLBFS) {
6306 return;
6307 }
6308
6309 size_t lp = os::large_page_size();
6310
6311 for (size_t size = lp; size <= lp * 10; size += lp) {
6312 test_reserve_memory_special_huge_tlbfs_only(size);
6313 }
6314 }
6315
6316 static void test_reserve_memory_special_huge_tlbfs_mixed(size_t size, size_t alignment) {
6317 if (!UseHugeTLBFS) {
6318 return;
6319 }
6320
6321 test_log("test_reserve_memory_special_huge_tlbfs_mixed(" SIZE_FORMAT ", " SIZE_FORMAT ")",
6322 size, alignment);
6323
6324 assert(size >= os::large_page_size(), "Incorrect input to test");
6325
6326 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, NULL, false);
6327
6328 if (addr != NULL) {
6329 small_page_write(addr, size);
6330
6331 os::Linux::release_memory_special_huge_tlbfs(addr, size);
6332 }
6333 }
6334
6335 static void test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(size_t size) {
6336 size_t lp = os::large_page_size();
6337 size_t ag = os::vm_allocation_granularity();
6338
6339 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) {
6340 test_reserve_memory_special_huge_tlbfs_mixed(size, alignment);
6341 }
6342 }
6343
6344 static void test_reserve_memory_special_huge_tlbfs_mixed() {
6345 size_t lp = os::large_page_size();
6346 size_t ag = os::vm_allocation_granularity();
6347
6348 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp);
6349 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + ag);
6350 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + lp / 2);
6351 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2);
6352 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 + ag);
6353 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 - ag);
6354 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 + lp / 2);
6355 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10);
6356 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10 + lp / 2);
6357 }
6358
6359 static void test_reserve_memory_special_huge_tlbfs() {
6360 if (!UseHugeTLBFS) {
6361 return;
6362 }
6363
6364 test_reserve_memory_special_huge_tlbfs_only();
6365 test_reserve_memory_special_huge_tlbfs_mixed();
6366 }
6367
6368 static void test_reserve_memory_special_shm(size_t size, size_t alignment) {
6369 if (!UseSHM) {
6370 return;
6371 }
6372
6373 test_log("test_reserve_memory_special_shm(" SIZE_FORMAT ", " SIZE_FORMAT ")", size, alignment);
6374
6375 char* addr = os::Linux::reserve_memory_special_shm(size, alignment, NULL, false);
6376
6377 if (addr != NULL) {
6378 assert(is_ptr_aligned(addr, alignment), "Check");
6379 assert(is_ptr_aligned(addr, os::large_page_size()), "Check");
6380
6381 small_page_write(addr, size);
6382
6383 os::Linux::release_memory_special_shm(addr, size);
6384 }
6385 }
6386
6387 static void test_reserve_memory_special_shm() {
6388 size_t lp = os::large_page_size();
6389 size_t ag = os::vm_allocation_granularity();
6390
6391 for (size_t size = ag; size < lp * 3; size += ag) {
6392 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) {
6393 test_reserve_memory_special_shm(size, alignment);
6394 }
6395 }
6396 }
6397
6398 static void test() {
6399 test_reserve_memory_special_huge_tlbfs();
6400 test_reserve_memory_special_shm();
6401 }
6402 };
6403
6404 void TestReserveMemorySpecial_test() {
6405 TestReserveMemorySpecial::test();
6406 }
6407
6408 #endif