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
107 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
108
109 // if RUSAGE_THREAD for getrusage() has not been defined, do it here. The code calling
110 // getrusage() is prepared to handle the associated failure.
111 #ifndef RUSAGE_THREAD
112 #define RUSAGE_THREAD (1) /* only the calling thread */
113 #endif
114
115 #define MAX_PATH (2 * K)
116
117 #define MAX_SECS 100000000
118
119 // for timer info max values which include all bits
120 #define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF)
121
122 #define LARGEPAGES_BIT (1 << 6)
123 ////////////////////////////////////////////////////////////////////////////////
124 // global variables
125 julong os::Linux::_physical_memory = 0;
126
127 address os::Linux::_initial_thread_stack_bottom = NULL;
128 uintptr_t os::Linux::_initial_thread_stack_size = 0;
129
130 int (*os::Linux::_clock_gettime)(clockid_t, struct timespec *) = NULL;
131 int (*os::Linux::_pthread_getcpuclockid)(pthread_t, clockid_t *) = NULL;
132 Mutex* os::Linux::_createThread_lock = NULL;
133 pthread_t os::Linux::_main_thread;
134 int os::Linux::_page_size = -1;
135 const int os::Linux::_vm_default_page_size = (8 * K);
136 bool os::Linux::_is_floating_stack = false;
137 bool os::Linux::_is_NPTL = false;
138 bool os::Linux::_supports_fast_thread_cpu_time = false;
139 const char * os::Linux::_glibc_version = NULL;
140 const char * os::Linux::_libpthread_version = NULL;
141 pthread_condattr_t os::Linux::_condattr[1];
142
143 static jlong initial_time_count=0;
144
145 static int clock_tics_per_sec = 100;
146
147 // For diagnostics to print a message once. see run_periodic_checks
148 static sigset_t check_signal_done;
149 static bool check_signals = true;
150
151 static pid_t _initial_pid = 0;
152
153 /* Signal number used to suspend/resume a thread */
154
155 /* do not use any signal number less than SIGSEGV, see 4355769 */
156 static int SR_signum = SIGUSR2;
157 sigset_t SR_sigset;
158
159 /* Used to protect dlsym() calls */
160 static pthread_mutex_t dl_mutex;
161
162 // Declarations
163 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time);
164
165 #ifdef JAVASE_EMBEDDED
166 class MemNotifyThread: public Thread {
167 friend class VMStructs;
168 public:
169 virtual void run();
170
171 private:
172 static MemNotifyThread* _memnotify_thread;
173 int _fd;
174
175 public:
176
177 // Constructor
178 MemNotifyThread(int fd);
179
180 // Tester
181 bool is_memnotify_thread() const { return true; }
182
183 // Printing
184 char* name() const { return (char*)"Linux MemNotify Thread"; }
185
186 // Returns the single instance of the MemNotifyThread
187 static MemNotifyThread* memnotify_thread() { return _memnotify_thread; }
188
189 // Create and start the single instance of MemNotifyThread
190 static void start();
191 };
192 #endif // JAVASE_EMBEDDED
193
194 // utility functions
195
196 static int SR_initialize();
197
198 julong os::available_memory() {
199 return Linux::available_memory();
200 }
201
202 julong os::Linux::available_memory() {
203 // values in struct sysinfo are "unsigned long"
204 struct sysinfo si;
205 sysinfo(&si);
206
207 return (julong)si.freeram * si.mem_unit;
208 }
209
210 julong os::physical_memory() {
211 return Linux::physical_memory();
212 }
213
214 ////////////////////////////////////////////////////////////////////////////////
215 // environment support
216
217 bool os::getenv(const char* name, char* buf, int len) {
218 const char* val = ::getenv(name);
219 if (val != NULL && strlen(val) < (size_t)len) {
220 strcpy(buf, val);
221 return true;
222 }
223 if (len > 0) buf[0] = 0; // return a null string
224 return false;
225 }
226
227
228 // Return true if user is running as root.
229
230 bool os::have_special_privileges() {
231 static bool init = false;
232 static bool privileges = false;
233 if (!init) {
234 privileges = (getuid() != geteuid()) || (getgid() != getegid());
235 init = true;
236 }
237 return privileges;
238 }
239
240
241 #ifndef SYS_gettid
242 // i386: 224, ia64: 1105, amd64: 186, sparc 143
243 #ifdef __ia64__
244 #define SYS_gettid 1105
245 #elif __i386__
246 #define SYS_gettid 224
247 #elif __amd64__
248 #define SYS_gettid 186
249 #elif __sparc__
250 #define SYS_gettid 143
251 #else
252 #error define gettid for the arch
253 #endif
254 #endif
255
256 // Cpu architecture string
257 #if defined(ZERO)
258 static char cpu_arch[] = ZERO_LIBARCH;
259 #elif defined(IA64)
260 static char cpu_arch[] = "ia64";
261 #elif defined(IA32)
262 static char cpu_arch[] = "i386";
263 #elif defined(AMD64)
264 static char cpu_arch[] = "amd64";
265 #elif defined(ARM)
266 static char cpu_arch[] = "arm";
267 #elif defined(PPC32)
268 static char cpu_arch[] = "ppc";
269 #elif defined(PPC64)
270 static char cpu_arch[] = "ppc64";
271 #elif defined(SPARC)
272 # ifdef _LP64
273 static char cpu_arch[] = "sparcv9";
274 # else
275 static char cpu_arch[] = "sparc";
276 # endif
277 #else
278 #error Add appropriate cpu_arch setting
279 #endif
280
281
282 // pid_t gettid()
283 //
284 // Returns the kernel thread id of the currently running thread. Kernel
285 // thread id is used to access /proc.
286 //
287 // (Note that getpid() on LinuxThreads returns kernel thread id too; but
288 // on NPTL, it returns the same pid for all threads, as required by POSIX.)
289 //
290 pid_t os::Linux::gettid() {
291 int rslt = syscall(SYS_gettid);
292 if (rslt == -1) {
293 // old kernel, no NPTL support
294 return getpid();
295 } else {
296 return (pid_t)rslt;
297 }
298 }
299
300 // Most versions of linux have a bug where the number of processors are
301 // determined by looking at the /proc file system. In a chroot environment,
302 // the system call returns 1. This causes the VM to act as if it is
303 // a single processor and elide locking (see is_MP() call).
304 static bool unsafe_chroot_detected = false;
305 static const char *unstable_chroot_error = "/proc file system not found.\n"
306 "Java may be unstable running multithreaded in a chroot "
307 "environment on Linux when /proc filesystem is not mounted.";
308
309 void os::Linux::initialize_system_info() {
310 set_processor_count(sysconf(_SC_NPROCESSORS_CONF));
311 if (processor_count() == 1) {
312 pid_t pid = os::Linux::gettid();
313 char fname[32];
314 jio_snprintf(fname, sizeof(fname), "/proc/%d", pid);
315 FILE *fp = fopen(fname, "r");
316 if (fp == NULL) {
317 unsafe_chroot_detected = true;
318 } else {
319 fclose(fp);
320 }
321 }
322 _physical_memory = (julong)sysconf(_SC_PHYS_PAGES) * (julong)sysconf(_SC_PAGESIZE);
323 assert(processor_count() > 0, "linux error");
324 }
325
326 void os::init_system_properties_values() {
327 // The next steps are taken in the product version:
328 //
329 // Obtain the JAVA_HOME value from the location of libjvm.so.
330 // This library should be located at:
331 // <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm.so.
332 //
333 // If "/jre/lib/" appears at the right place in the path, then we
334 // assume libjvm.so is installed in a JDK and we use this path.
335 //
336 // Otherwise exit with message: "Could not create the Java virtual machine."
337 //
338 // The following extra steps are taken in the debugging version:
339 //
340 // If "/jre/lib/" does NOT appear at the right place in the path
341 // instead of exit check for $JAVA_HOME environment variable.
342 //
343 // If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>,
344 // then we append a fake suffix "hotspot/libjvm.so" to this path so
345 // it looks like libjvm.so is installed there
346 // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm.so.
347 //
348 // Otherwise exit.
349 //
350 // Important note: if the location of libjvm.so changes this
351 // code needs to be changed accordingly.
352
353 // See ld(1):
354 // The linker uses the following search paths to locate required
355 // shared libraries:
356 // 1: ...
357 // ...
358 // 7: The default directories, normally /lib and /usr/lib.
359 #if defined(AMD64) || defined(_LP64) && (defined(SPARC) || defined(PPC) || defined(S390))
360 #define DEFAULT_LIBPATH "/usr/lib64:/lib64:/lib:/usr/lib"
361 #else
362 #define DEFAULT_LIBPATH "/lib:/usr/lib"
363 #endif
364
365 // Base path of extensions installed on the system.
366 #define SYS_EXT_DIR "/usr/java/packages"
367 #define EXTENSIONS_DIR "/lib/ext"
368 #define ENDORSED_DIR "/lib/endorsed"
369
370 // Buffer that fits several sprintfs.
371 // Note that the space for the colon and the trailing null are provided
372 // by the nulls included by the sizeof operator.
373 const size_t bufsize =
374 MAX3((size_t)MAXPATHLEN, // For dll_dir & friends.
375 (size_t)MAXPATHLEN + sizeof(EXTENSIONS_DIR) + sizeof(SYS_EXT_DIR) + sizeof(EXTENSIONS_DIR), // extensions dir
376 (size_t)MAXPATHLEN + sizeof(ENDORSED_DIR)); // endorsed dir
377 char *buf = (char *)NEW_C_HEAP_ARRAY(char, bufsize, mtInternal);
378
379 // sysclasspath, java_home, dll_dir
380 {
381 char *pslash;
382 os::jvm_path(buf, bufsize);
383
384 // Found the full path to libjvm.so.
385 // Now cut the path to <java_home>/jre if we can.
386 *(strrchr(buf, '/')) = '\0'; // Get rid of /libjvm.so.
387 pslash = strrchr(buf, '/');
388 if (pslash != NULL) {
389 *pslash = '\0'; // Get rid of /{client|server|hotspot}.
390 }
391 Arguments::set_dll_dir(buf);
392
393 if (pslash != NULL) {
394 pslash = strrchr(buf, '/');
395 if (pslash != NULL) {
396 *pslash = '\0'; // Get rid of /<arch>.
397 pslash = strrchr(buf, '/');
398 if (pslash != NULL) {
399 *pslash = '\0'; // Get rid of /lib.
400 }
401 }
402 }
403 Arguments::set_java_home(buf);
404 set_boot_path('/', ':');
405 }
406
407 // Where to look for native libraries.
408 //
409 // Note: Due to a legacy implementation, most of the library path
410 // is set in the launcher. This was to accomodate linking restrictions
411 // on legacy Linux implementations (which are no longer supported).
412 // Eventually, all the library path setting will be done here.
413 //
414 // However, to prevent the proliferation of improperly built native
415 // libraries, the new path component /usr/java/packages is added here.
416 // Eventually, all the library path setting will be done here.
417 {
418 // Get the user setting of LD_LIBRARY_PATH, and prepended it. It
419 // should always exist (until the legacy problem cited above is
420 // addressed).
421 const char *v = ::getenv("LD_LIBRARY_PATH");
422 const char *v_colon = ":";
423 if (v == NULL) { v = ""; v_colon = ""; }
424 // That's +1 for the colon and +1 for the trailing '\0'.
425 char *ld_library_path = (char *)NEW_C_HEAP_ARRAY(char,
426 strlen(v) + 1 +
427 sizeof(SYS_EXT_DIR) + sizeof("/lib/") + strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH) + 1,
428 mtInternal);
429 sprintf(ld_library_path, "%s%s" SYS_EXT_DIR "/lib/%s:" DEFAULT_LIBPATH, v, v_colon, cpu_arch);
430 Arguments::set_library_path(ld_library_path);
431 FREE_C_HEAP_ARRAY(char, ld_library_path, mtInternal);
432 }
433
434 // Extensions directories.
435 sprintf(buf, "%s" EXTENSIONS_DIR ":" SYS_EXT_DIR EXTENSIONS_DIR, Arguments::get_java_home());
436 Arguments::set_ext_dirs(buf);
437
438 // Endorsed standards default directory.
439 sprintf(buf, "%s" ENDORSED_DIR, Arguments::get_java_home());
440 Arguments::set_endorsed_dirs(buf);
441
442 FREE_C_HEAP_ARRAY(char, buf, mtInternal);
443
444 #undef DEFAULT_LIBPATH
445 #undef SYS_EXT_DIR
446 #undef EXTENSIONS_DIR
447 #undef ENDORSED_DIR
448 }
449
450 ////////////////////////////////////////////////////////////////////////////////
451 // breakpoint support
452
453 void os::breakpoint() {
454 BREAKPOINT;
455 }
456
457 extern "C" void breakpoint() {
458 // use debugger to set breakpoint here
459 }
460
461 ////////////////////////////////////////////////////////////////////////////////
462 // signal support
463
464 debug_only(static bool signal_sets_initialized = false);
465 static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs;
466
467 bool os::Linux::is_sig_ignored(int sig) {
468 struct sigaction oact;
469 sigaction(sig, (struct sigaction*)NULL, &oact);
470 void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*, oact.sa_sigaction)
471 : CAST_FROM_FN_PTR(void*, oact.sa_handler);
472 if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN))
473 return true;
474 else
475 return false;
476 }
477
478 void os::Linux::signal_sets_init() {
479 // Should also have an assertion stating we are still single-threaded.
480 assert(!signal_sets_initialized, "Already initialized");
481 // Fill in signals that are necessarily unblocked for all threads in
482 // the VM. Currently, we unblock the following signals:
483 // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden
484 // by -Xrs (=ReduceSignalUsage));
485 // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all
486 // other threads. The "ReduceSignalUsage" boolean tells us not to alter
487 // the dispositions or masks wrt these signals.
488 // Programs embedding the VM that want to use the above signals for their
489 // own purposes must, at this time, use the "-Xrs" option to prevent
490 // interference with shutdown hooks and BREAK_SIGNAL thread dumping.
491 // (See bug 4345157, and other related bugs).
492 // In reality, though, unblocking these signals is really a nop, since
493 // these signals are not blocked by default.
494 sigemptyset(&unblocked_sigs);
495 sigemptyset(&allowdebug_blocked_sigs);
496 sigaddset(&unblocked_sigs, SIGILL);
497 sigaddset(&unblocked_sigs, SIGSEGV);
498 sigaddset(&unblocked_sigs, SIGBUS);
499 sigaddset(&unblocked_sigs, SIGFPE);
500 #if defined(PPC64)
501 sigaddset(&unblocked_sigs, SIGTRAP);
502 #endif
503 sigaddset(&unblocked_sigs, SR_signum);
504
505 if (!ReduceSignalUsage) {
506 if (!os::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) {
507 sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL);
508 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL);
509 }
510 if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) {
511 sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL);
512 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL);
513 }
514 if (!os::Linux::is_sig_ignored(SHUTDOWN3_SIGNAL)) {
515 sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL);
516 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN3_SIGNAL);
517 }
518 }
519 // Fill in signals that are blocked by all but the VM thread.
520 sigemptyset(&vm_sigs);
521 if (!ReduceSignalUsage)
522 sigaddset(&vm_sigs, BREAK_SIGNAL);
523 debug_only(signal_sets_initialized = true);
524
525 }
526
527 // These are signals that are unblocked while a thread is running Java.
528 // (For some reason, they get blocked by default.)
529 sigset_t* os::Linux::unblocked_signals() {
530 assert(signal_sets_initialized, "Not initialized");
531 return &unblocked_sigs;
532 }
533
534 // These are the signals that are blocked while a (non-VM) thread is
535 // running Java. Only the VM thread handles these signals.
536 sigset_t* os::Linux::vm_signals() {
537 assert(signal_sets_initialized, "Not initialized");
538 return &vm_sigs;
539 }
540
541 // These are signals that are blocked during cond_wait to allow debugger in
542 sigset_t* os::Linux::allowdebug_blocked_signals() {
543 assert(signal_sets_initialized, "Not initialized");
544 return &allowdebug_blocked_sigs;
545 }
546
547 void os::Linux::hotspot_sigmask(Thread* thread) {
548
549 //Save caller's signal mask before setting VM signal mask
550 sigset_t caller_sigmask;
551 pthread_sigmask(SIG_BLOCK, NULL, &caller_sigmask);
552
553 OSThread* osthread = thread->osthread();
554 osthread->set_caller_sigmask(caller_sigmask);
555
556 pthread_sigmask(SIG_UNBLOCK, os::Linux::unblocked_signals(), NULL);
557
558 if (!ReduceSignalUsage) {
559 if (thread->is_VM_thread()) {
560 // Only the VM thread handles BREAK_SIGNAL ...
561 pthread_sigmask(SIG_UNBLOCK, vm_signals(), NULL);
562 } else {
563 // ... all other threads block BREAK_SIGNAL
564 pthread_sigmask(SIG_BLOCK, vm_signals(), NULL);
565 }
566 }
567 }
568
569 //////////////////////////////////////////////////////////////////////////////
570 // detecting pthread library
571
572 void os::Linux::libpthread_init() {
573 // Save glibc and pthread version strings. Note that _CS_GNU_LIBC_VERSION
574 // and _CS_GNU_LIBPTHREAD_VERSION are supported in glibc >= 2.3.2. Use a
575 // generic name for earlier versions.
576 // Define macros here so we can build HotSpot on old systems.
577 # ifndef _CS_GNU_LIBC_VERSION
578 # define _CS_GNU_LIBC_VERSION 2
579 # endif
580 # ifndef _CS_GNU_LIBPTHREAD_VERSION
581 # define _CS_GNU_LIBPTHREAD_VERSION 3
582 # endif
583
584 size_t n = confstr(_CS_GNU_LIBC_VERSION, NULL, 0);
585 if (n > 0) {
586 char *str = (char *)malloc(n, mtInternal);
587 confstr(_CS_GNU_LIBC_VERSION, str, n);
588 os::Linux::set_glibc_version(str);
589 } else {
590 // _CS_GNU_LIBC_VERSION is not supported, try gnu_get_libc_version()
591 static char _gnu_libc_version[32];
592 jio_snprintf(_gnu_libc_version, sizeof(_gnu_libc_version),
593 "glibc %s %s", gnu_get_libc_version(), gnu_get_libc_release());
594 os::Linux::set_glibc_version(_gnu_libc_version);
595 }
596
597 n = confstr(_CS_GNU_LIBPTHREAD_VERSION, NULL, 0);
598 if (n > 0) {
599 char *str = (char *)malloc(n, mtInternal);
600 confstr(_CS_GNU_LIBPTHREAD_VERSION, str, n);
601 // Vanilla RH-9 (glibc 2.3.2) has a bug that confstr() always tells
602 // us "NPTL-0.29" even we are running with LinuxThreads. Check if this
603 // is the case. LinuxThreads has a hard limit on max number of threads.
604 // So sysconf(_SC_THREAD_THREADS_MAX) will return a positive value.
605 // On the other hand, NPTL does not have such a limit, sysconf()
606 // will return -1 and errno is not changed. Check if it is really NPTL.
607 if (strcmp(os::Linux::glibc_version(), "glibc 2.3.2") == 0 &&
608 strstr(str, "NPTL") &&
609 sysconf(_SC_THREAD_THREADS_MAX) > 0) {
610 free(str);
611 os::Linux::set_libpthread_version("linuxthreads");
612 } else {
613 os::Linux::set_libpthread_version(str);
614 }
615 } else {
616 // glibc before 2.3.2 only has LinuxThreads.
617 os::Linux::set_libpthread_version("linuxthreads");
618 }
619
620 if (strstr(libpthread_version(), "NPTL")) {
621 os::Linux::set_is_NPTL();
622 } else {
623 os::Linux::set_is_LinuxThreads();
624 }
625
626 // LinuxThreads have two flavors: floating-stack mode, which allows variable
627 // stack size; and fixed-stack mode. NPTL is always floating-stack.
628 if (os::Linux::is_NPTL() || os::Linux::supports_variable_stack_size()) {
629 os::Linux::set_is_floating_stack();
630 }
631 }
632
633 /////////////////////////////////////////////////////////////////////////////
634 // thread stack
635
636 // Force Linux kernel to expand current thread stack. If "bottom" is close
637 // to the stack guard, caller should block all signals.
638 //
639 // MAP_GROWSDOWN:
640 // A special mmap() flag that is used to implement thread stacks. It tells
641 // kernel that the memory region should extend downwards when needed. This
642 // allows early versions of LinuxThreads to only mmap the first few pages
643 // when creating a new thread. Linux kernel will automatically expand thread
644 // stack as needed (on page faults).
645 //
646 // However, because the memory region of a MAP_GROWSDOWN stack can grow on
647 // demand, if a page fault happens outside an already mapped MAP_GROWSDOWN
648 // region, it's hard to tell if the fault is due to a legitimate stack
649 // access or because of reading/writing non-exist memory (e.g. buffer
650 // overrun). As a rule, if the fault happens below current stack pointer,
651 // Linux kernel does not expand stack, instead a SIGSEGV is sent to the
652 // application (see Linux kernel fault.c).
653 //
654 // This Linux feature can cause SIGSEGV when VM bangs thread stack for
655 // stack overflow detection.
656 //
657 // Newer version of LinuxThreads (since glibc-2.2, or, RH-7.x) and NPTL do
658 // not use this flag. However, the stack of initial thread is not created
659 // by pthread, it is still MAP_GROWSDOWN. Also it's possible (though
660 // unlikely) that user code can create a thread with MAP_GROWSDOWN stack
661 // and then attach the thread to JVM.
662 //
663 // To get around the problem and allow stack banging on Linux, we need to
664 // manually expand thread stack after receiving the SIGSEGV.
665 //
666 // There are two ways to expand thread stack to address "bottom", we used
667 // both of them in JVM before 1.5:
668 // 1. adjust stack pointer first so that it is below "bottom", and then
669 // touch "bottom"
670 // 2. mmap() the page in question
671 //
672 // Now alternate signal stack is gone, it's harder to use 2. For instance,
673 // if current sp is already near the lower end of page 101, and we need to
674 // call mmap() to map page 100, it is possible that part of the mmap() frame
675 // will be placed in page 100. When page 100 is mapped, it is zero-filled.
676 // That will destroy the mmap() frame and cause VM to crash.
677 //
678 // The following code works by adjusting sp first, then accessing the "bottom"
679 // page to force a page fault. Linux kernel will then automatically expand the
680 // stack mapping.
681 //
682 // _expand_stack_to() assumes its frame size is less than page size, which
683 // should always be true if the function is not inlined.
684
685 #if __GNUC__ < 3 // gcc 2.x does not support noinline attribute
686 #define NOINLINE
687 #else
688 #define NOINLINE __attribute__ ((noinline))
689 #endif
690
691 static void _expand_stack_to(address bottom) NOINLINE;
692
693 static void _expand_stack_to(address bottom) {
694 address sp;
695 size_t size;
696 volatile char *p;
697
698 // Adjust bottom to point to the largest address within the same page, it
699 // gives us a one-page buffer if alloca() allocates slightly more memory.
700 bottom = (address)align_size_down((uintptr_t)bottom, os::Linux::page_size());
701 bottom += os::Linux::page_size() - 1;
702
703 // sp might be slightly above current stack pointer; if that's the case, we
704 // will alloca() a little more space than necessary, which is OK. Don't use
705 // os::current_stack_pointer(), as its result can be slightly below current
706 // stack pointer, causing us to not alloca enough to reach "bottom".
707 sp = (address)&sp;
708
709 if (sp > bottom) {
710 size = sp - bottom;
711 p = (volatile char *)alloca(size);
712 assert(p != NULL && p <= (volatile char *)bottom, "alloca problem?");
713 p[0] = '\0';
714 }
715 }
716
717 bool os::Linux::manually_expand_stack(JavaThread * t, address addr) {
718 assert(t!=NULL, "just checking");
719 assert(t->osthread()->expanding_stack(), "expand should be set");
720 assert(t->stack_base() != NULL, "stack_base was not initialized");
721
722 if (addr < t->stack_base() && addr >= t->stack_yellow_zone_base()) {
723 sigset_t mask_all, old_sigset;
724 sigfillset(&mask_all);
725 pthread_sigmask(SIG_SETMASK, &mask_all, &old_sigset);
726 _expand_stack_to(addr);
727 pthread_sigmask(SIG_SETMASK, &old_sigset, NULL);
728 return true;
729 }
730 return false;
731 }
732
733 //////////////////////////////////////////////////////////////////////////////
734 // create new thread
735
736 static address highest_vm_reserved_address();
737
738 // check if it's safe to start a new thread
739 static bool _thread_safety_check(Thread* thread) {
740 if (os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack()) {
741 // Fixed stack LinuxThreads (SuSE Linux/x86, and some versions of Redhat)
742 // Heap is mmap'ed at lower end of memory space. Thread stacks are
743 // allocated (MAP_FIXED) from high address space. Every thread stack
744 // occupies a fixed size slot (usually 2Mbytes, but user can change
745 // it to other values if they rebuild LinuxThreads).
746 //
747 // Problem with MAP_FIXED is that mmap() can still succeed even part of
748 // the memory region has already been mmap'ed. That means if we have too
749 // many threads and/or very large heap, eventually thread stack will
750 // collide with heap.
751 //
752 // Here we try to prevent heap/stack collision by comparing current
753 // stack bottom with the highest address that has been mmap'ed by JVM
754 // plus a safety margin for memory maps created by native code.
755 //
756 // This feature can be disabled by setting ThreadSafetyMargin to 0
757 //
758 if (ThreadSafetyMargin > 0) {
759 address stack_bottom = os::current_stack_base() - os::current_stack_size();
760
761 // not safe if our stack extends below the safety margin
762 return stack_bottom - ThreadSafetyMargin >= highest_vm_reserved_address();
763 } else {
764 return true;
765 }
766 } else {
767 // Floating stack LinuxThreads or NPTL:
768 // Unlike fixed stack LinuxThreads, thread stacks are not MAP_FIXED. When
769 // there's not enough space left, pthread_create() will fail. If we come
770 // here, that means enough space has been reserved for stack.
771 return true;
772 }
773 }
774
775 // Thread start routine for all newly created threads
776 static void *java_start(Thread *thread) {
777 // Try to randomize the cache line index of hot stack frames.
778 // This helps when threads of the same stack traces evict each other's
779 // cache lines. The threads can be either from the same JVM instance, or
780 // from different JVM instances. The benefit is especially true for
781 // processors with hyperthreading technology.
782 static int counter = 0;
783 int pid = os::current_process_id();
784 alloca(((pid ^ counter++) & 7) * 128);
785
786 ThreadLocalStorage::set_thread(thread);
787
788 OSThread* osthread = thread->osthread();
789 Monitor* sync = osthread->startThread_lock();
790
791 // non floating stack LinuxThreads needs extra check, see above
792 if (!_thread_safety_check(thread)) {
793 // notify parent thread
794 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
795 osthread->set_state(ZOMBIE);
796 sync->notify_all();
797 return NULL;
798 }
799
800 // thread_id is kernel thread id (similar to Solaris LWP id)
801 osthread->set_thread_id(os::Linux::gettid());
802
803 if (UseNUMA) {
804 int lgrp_id = os::numa_get_group_id();
805 if (lgrp_id != -1) {
806 thread->set_lgrp_id(lgrp_id);
807 }
808 }
809 // initialize signal mask for this thread
810 os::Linux::hotspot_sigmask(thread);
811
812 // initialize floating point control register
813 os::Linux::init_thread_fpu_state();
814
815 // handshaking with parent thread
816 {
817 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
818
819 // notify parent thread
820 osthread->set_state(INITIALIZED);
821 sync->notify_all();
822
823 // wait until os::start_thread()
824 while (osthread->get_state() == INITIALIZED) {
825 sync->wait(Mutex::_no_safepoint_check_flag);
826 }
827 }
828
829 // call one more level start routine
830 thread->run();
831
832 return 0;
833 }
834
835 bool os::create_thread(Thread* thread, ThreadType thr_type, size_t stack_size) {
836 assert(thread->osthread() == NULL, "caller responsible");
837
838 // Allocate the OSThread object
839 OSThread* osthread = new OSThread(NULL, NULL);
840 if (osthread == NULL) {
841 return false;
842 }
843
844 // set the correct thread state
845 osthread->set_thread_type(thr_type);
846
847 // Initial state is ALLOCATED but not INITIALIZED
848 osthread->set_state(ALLOCATED);
849
850 thread->set_osthread(osthread);
851
852 // init thread attributes
853 pthread_attr_t attr;
854 pthread_attr_init(&attr);
855 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
856
857 // stack size
858 if (os::Linux::supports_variable_stack_size()) {
859 // calculate stack size if it's not specified by caller
860 if (stack_size == 0) {
861 stack_size = os::Linux::default_stack_size(thr_type);
862
863 switch (thr_type) {
864 case os::java_thread:
865 // Java threads use ThreadStackSize which default value can be
866 // changed with the flag -Xss
867 assert(JavaThread::stack_size_at_create() > 0, "this should be set");
868 stack_size = JavaThread::stack_size_at_create();
869 break;
870 case os::compiler_thread:
871 if (CompilerThreadStackSize > 0) {
872 stack_size = (size_t)(CompilerThreadStackSize * K);
873 break;
874 } // else fall through:
875 // use VMThreadStackSize if CompilerThreadStackSize is not defined
876 case os::vm_thread:
877 case os::pgc_thread:
878 case os::cgc_thread:
879 case os::watcher_thread:
880 if (VMThreadStackSize > 0) stack_size = (size_t)(VMThreadStackSize * K);
881 break;
882 }
883 }
884
885 stack_size = MAX2(stack_size, os::Linux::min_stack_allowed);
886 pthread_attr_setstacksize(&attr, stack_size);
887 } else {
888 // let pthread_create() pick the default value.
889 }
890
891 // glibc guard page
892 pthread_attr_setguardsize(&attr, os::Linux::default_guard_size(thr_type));
893
894 ThreadState state;
895
896 {
897 // Serialize thread creation if we are running with fixed stack LinuxThreads
898 bool lock = os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack();
899 if (lock) {
900 os::Linux::createThread_lock()->lock_without_safepoint_check();
901 }
902
903 pthread_t tid;
904 int ret = pthread_create(&tid, &attr, (void* (*)(void*)) java_start, thread);
905
906 pthread_attr_destroy(&attr);
907
908 if (ret != 0) {
909 if (PrintMiscellaneous && (Verbose || WizardMode)) {
910 perror("pthread_create()");
911 }
912 // Need to clean up stuff we've allocated so far
913 thread->set_osthread(NULL);
914 delete osthread;
915 if (lock) os::Linux::createThread_lock()->unlock();
916 return false;
917 }
918
919 // Store pthread info into the OSThread
920 osthread->set_pthread_id(tid);
921
922 // Wait until child thread is either initialized or aborted
923 {
924 Monitor* sync_with_child = osthread->startThread_lock();
925 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
926 while ((state = osthread->get_state()) == ALLOCATED) {
927 sync_with_child->wait(Mutex::_no_safepoint_check_flag);
928 }
929 }
930
931 if (lock) {
932 os::Linux::createThread_lock()->unlock();
933 }
934 }
935
936 // Aborted due to thread limit being reached
937 if (state == ZOMBIE) {
938 thread->set_osthread(NULL);
939 delete osthread;
940 return false;
941 }
942
943 // The thread is returned suspended (in state INITIALIZED),
944 // and is started higher up in the call chain
945 assert(state == INITIALIZED, "race condition");
946 return true;
947 }
948
949 /////////////////////////////////////////////////////////////////////////////
950 // attach existing thread
951
952 // bootstrap the main thread
953 bool os::create_main_thread(JavaThread* thread) {
954 assert(os::Linux::_main_thread == pthread_self(), "should be called inside main thread");
955 return create_attached_thread(thread);
956 }
957
958 bool os::create_attached_thread(JavaThread* thread) {
959 #ifdef ASSERT
960 thread->verify_not_published();
961 #endif
962
963 // Allocate the OSThread object
964 OSThread* osthread = new OSThread(NULL, NULL);
965
966 if (osthread == NULL) {
967 return false;
968 }
969
970 // Store pthread info into the OSThread
971 osthread->set_thread_id(os::Linux::gettid());
972 osthread->set_pthread_id(::pthread_self());
973
974 // initialize floating point control register
975 os::Linux::init_thread_fpu_state();
976
977 // Initial thread state is RUNNABLE
978 osthread->set_state(RUNNABLE);
979
980 thread->set_osthread(osthread);
981
982 if (UseNUMA) {
983 int lgrp_id = os::numa_get_group_id();
984 if (lgrp_id != -1) {
985 thread->set_lgrp_id(lgrp_id);
986 }
987 }
988
989 if (os::Linux::is_initial_thread()) {
990 // If current thread is initial thread, its stack is mapped on demand,
991 // see notes about MAP_GROWSDOWN. Here we try to force kernel to map
992 // the entire stack region to avoid SEGV in stack banging.
993 // It is also useful to get around the heap-stack-gap problem on SuSE
994 // kernel (see 4821821 for details). We first expand stack to the top
995 // of yellow zone, then enable stack yellow zone (order is significant,
996 // enabling yellow zone first will crash JVM on SuSE Linux), so there
997 // is no gap between the last two virtual memory regions.
998
999 JavaThread *jt = (JavaThread *)thread;
1000 address addr = jt->stack_yellow_zone_base();
1001 assert(addr != NULL, "initialization problem?");
1002 assert(jt->stack_available(addr) > 0, "stack guard should not be enabled");
1003
1004 osthread->set_expanding_stack();
1005 os::Linux::manually_expand_stack(jt, addr);
1006 osthread->clear_expanding_stack();
1007 }
1008
1009 // initialize signal mask for this thread
1010 // and save the caller's signal mask
1011 os::Linux::hotspot_sigmask(thread);
1012
1013 return true;
1014 }
1015
1016 void os::pd_start_thread(Thread* thread) {
1017 OSThread * osthread = thread->osthread();
1018 assert(osthread->get_state() != INITIALIZED, "just checking");
1019 Monitor* sync_with_child = osthread->startThread_lock();
1020 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
1021 sync_with_child->notify();
1022 }
1023
1024 // Free Linux resources related to the OSThread
1025 void os::free_thread(OSThread* osthread) {
1026 assert(osthread != NULL, "osthread not set");
1027
1028 if (Thread::current()->osthread() == osthread) {
1029 // Restore caller's signal mask
1030 sigset_t sigmask = osthread->caller_sigmask();
1031 pthread_sigmask(SIG_SETMASK, &sigmask, NULL);
1032 }
1033
1034 delete osthread;
1035 }
1036
1037 //////////////////////////////////////////////////////////////////////////////
1038 // thread local storage
1039
1040 // Restore the thread pointer if the destructor is called. This is in case
1041 // someone from JNI code sets up a destructor with pthread_key_create to run
1042 // detachCurrentThread on thread death. Unless we restore the thread pointer we
1043 // will hang or crash. When detachCurrentThread is called the key will be set
1044 // to null and we will not be called again. If detachCurrentThread is never
1045 // called we could loop forever depending on the pthread implementation.
1046 static void restore_thread_pointer(void* p) {
1047 Thread* thread = (Thread*) p;
1048 os::thread_local_storage_at_put(ThreadLocalStorage::thread_index(), thread);
1049 }
1050
1051 int os::allocate_thread_local_storage() {
1052 pthread_key_t key;
1053 int rslt = pthread_key_create(&key, restore_thread_pointer);
1054 assert(rslt == 0, "cannot allocate thread local storage");
1055 return (int)key;
1056 }
1057
1058 // Note: This is currently not used by VM, as we don't destroy TLS key
1059 // on VM exit.
1060 void os::free_thread_local_storage(int index) {
1061 int rslt = pthread_key_delete((pthread_key_t)index);
1062 assert(rslt == 0, "invalid index");
1063 }
1064
1065 void os::thread_local_storage_at_put(int index, void* value) {
1066 int rslt = pthread_setspecific((pthread_key_t)index, value);
1067 assert(rslt == 0, "pthread_setspecific failed");
1068 }
1069
1070 extern "C" Thread* get_thread() {
1071 return ThreadLocalStorage::thread();
1072 }
1073
1074 //////////////////////////////////////////////////////////////////////////////
1075 // initial thread
1076
1077 // Check if current thread is the initial thread, similar to Solaris thr_main.
1078 bool os::Linux::is_initial_thread(void) {
1079 char dummy;
1080 // If called before init complete, thread stack bottom will be null.
1081 // Can be called if fatal error occurs before initialization.
1082 if (initial_thread_stack_bottom() == NULL) return false;
1083 assert(initial_thread_stack_bottom() != NULL &&
1084 initial_thread_stack_size() != 0,
1085 "os::init did not locate initial thread's stack region");
1086 if ((address)&dummy >= initial_thread_stack_bottom() &&
1087 (address)&dummy < initial_thread_stack_bottom() + initial_thread_stack_size())
1088 return true;
1089 else return false;
1090 }
1091
1092 // Find the virtual memory area that contains addr
1093 static bool find_vma(address addr, address* vma_low, address* vma_high) {
1094 FILE *fp = fopen("/proc/self/maps", "r");
1095 if (fp) {
1096 address low, high;
1097 while (!feof(fp)) {
1098 if (fscanf(fp, "%p-%p", &low, &high) == 2) {
1099 if (low <= addr && addr < high) {
1100 if (vma_low) *vma_low = low;
1101 if (vma_high) *vma_high = high;
1102 fclose(fp);
1103 return true;
1104 }
1105 }
1106 for (;;) {
1107 int ch = fgetc(fp);
1108 if (ch == EOF || ch == (int)'\n') break;
1109 }
1110 }
1111 fclose(fp);
1112 }
1113 return false;
1114 }
1115
1116 // Locate initial thread stack. This special handling of initial thread stack
1117 // is needed because pthread_getattr_np() on most (all?) Linux distros returns
1118 // bogus value for initial thread.
1119 void os::Linux::capture_initial_stack(size_t max_size) {
1120 // stack size is the easy part, get it from RLIMIT_STACK
1121 size_t stack_size;
1122 struct rlimit rlim;
1123 getrlimit(RLIMIT_STACK, &rlim);
1124 stack_size = rlim.rlim_cur;
1125
1126 // 6308388: a bug in ld.so will relocate its own .data section to the
1127 // lower end of primordial stack; reduce ulimit -s value a little bit
1128 // so we won't install guard page on ld.so's data section.
1129 stack_size -= 2 * page_size();
1130
1131 // 4441425: avoid crash with "unlimited" stack size on SuSE 7.1 or Redhat
1132 // 7.1, in both cases we will get 2G in return value.
1133 // 4466587: glibc 2.2.x compiled w/o "--enable-kernel=2.4.0" (RH 7.0,
1134 // SuSE 7.2, Debian) can not handle alternate signal stack correctly
1135 // for initial thread if its stack size exceeds 6M. Cap it at 2M,
1136 // in case other parts in glibc still assumes 2M max stack size.
1137 // FIXME: alt signal stack is gone, maybe we can relax this constraint?
1138 // Problem still exists RH7.2 (IA64 anyway) but 2MB is a little small
1139 if (stack_size > 2 * K * K IA64_ONLY(*2))
1140 stack_size = 2 * K * K IA64_ONLY(*2);
1141 // Try to figure out where the stack base (top) is. This is harder.
1142 //
1143 // When an application is started, glibc saves the initial stack pointer in
1144 // a global variable "__libc_stack_end", which is then used by system
1145 // libraries. __libc_stack_end should be pretty close to stack top. The
1146 // variable is available since the very early days. However, because it is
1147 // a private interface, it could disappear in the future.
1148 //
1149 // Linux kernel saves start_stack information in /proc/<pid>/stat. Similar
1150 // to __libc_stack_end, it is very close to stack top, but isn't the real
1151 // stack top. Note that /proc may not exist if VM is running as a chroot
1152 // program, so reading /proc/<pid>/stat could fail. Also the contents of
1153 // /proc/<pid>/stat could change in the future (though unlikely).
1154 //
1155 // We try __libc_stack_end first. If that doesn't work, look for
1156 // /proc/<pid>/stat. If neither of them works, we use current stack pointer
1157 // as a hint, which should work well in most cases.
1158
1159 uintptr_t stack_start;
1160
1161 // try __libc_stack_end first
1162 uintptr_t *p = (uintptr_t *)dlsym(RTLD_DEFAULT, "__libc_stack_end");
1163 if (p && *p) {
1164 stack_start = *p;
1165 } else {
1166 // see if we can get the start_stack field from /proc/self/stat
1167 FILE *fp;
1168 int pid;
1169 char state;
1170 int ppid;
1171 int pgrp;
1172 int session;
1173 int nr;
1174 int tpgrp;
1175 unsigned long flags;
1176 unsigned long minflt;
1177 unsigned long cminflt;
1178 unsigned long majflt;
1179 unsigned long cmajflt;
1180 unsigned long utime;
1181 unsigned long stime;
1182 long cutime;
1183 long cstime;
1184 long prio;
1185 long nice;
1186 long junk;
1187 long it_real;
1188 uintptr_t start;
1189 uintptr_t vsize;
1190 intptr_t rss;
1191 uintptr_t rsslim;
1192 uintptr_t scodes;
1193 uintptr_t ecode;
1194 int i;
1195
1196 // Figure what the primordial thread stack base is. Code is inspired
1197 // by email from Hans Boehm. /proc/self/stat begins with current pid,
1198 // followed by command name surrounded by parentheses, state, etc.
1199 char stat[2048];
1200 int statlen;
1201
1202 fp = fopen("/proc/self/stat", "r");
1203 if (fp) {
1204 statlen = fread(stat, 1, 2047, fp);
1205 stat[statlen] = '\0';
1206 fclose(fp);
1207
1208 // Skip pid and the command string. Note that we could be dealing with
1209 // weird command names, e.g. user could decide to rename java launcher
1210 // to "java 1.4.2 :)", then the stat file would look like
1211 // 1234 (java 1.4.2 :)) R ... ...
1212 // We don't really need to know the command string, just find the last
1213 // occurrence of ")" and then start parsing from there. See bug 4726580.
1214 char * s = strrchr(stat, ')');
1215
1216 i = 0;
1217 if (s) {
1218 // Skip blank chars
1219 do s++; while (isspace(*s));
1220
1221 #define _UFM UINTX_FORMAT
1222 #define _DFM INTX_FORMAT
1223
1224 /* 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 */
1225 /* 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 */
1226 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,
1227 &state, /* 3 %c */
1228 &ppid, /* 4 %d */
1229 &pgrp, /* 5 %d */
1230 &session, /* 6 %d */
1231 &nr, /* 7 %d */
1232 &tpgrp, /* 8 %d */
1233 &flags, /* 9 %lu */
1234 &minflt, /* 10 %lu */
1235 &cminflt, /* 11 %lu */
1236 &majflt, /* 12 %lu */
1237 &cmajflt, /* 13 %lu */
1238 &utime, /* 14 %lu */
1239 &stime, /* 15 %lu */
1240 &cutime, /* 16 %ld */
1241 &cstime, /* 17 %ld */
1242 &prio, /* 18 %ld */
1243 &nice, /* 19 %ld */
1244 &junk, /* 20 %ld */
1245 &it_real, /* 21 %ld */
1246 &start, /* 22 UINTX_FORMAT */
1247 &vsize, /* 23 UINTX_FORMAT */
1248 &rss, /* 24 INTX_FORMAT */
1249 &rsslim, /* 25 UINTX_FORMAT */
1250 &scodes, /* 26 UINTX_FORMAT */
1251 &ecode, /* 27 UINTX_FORMAT */
1252 &stack_start); /* 28 UINTX_FORMAT */
1253 }
1254
1255 #undef _UFM
1256 #undef _DFM
1257
1258 if (i != 28 - 2) {
1259 assert(false, "Bad conversion from /proc/self/stat");
1260 // product mode - assume we are the initial thread, good luck in the
1261 // embedded case.
1262 warning("Can't detect initial thread stack location - bad conversion");
1263 stack_start = (uintptr_t) &rlim;
1264 }
1265 } else {
1266 // For some reason we can't open /proc/self/stat (for example, running on
1267 // FreeBSD with a Linux emulator, or inside chroot), this should work for
1268 // most cases, so don't abort:
1269 warning("Can't detect initial thread stack location - no /proc/self/stat");
1270 stack_start = (uintptr_t) &rlim;
1271 }
1272 }
1273
1274 // Now we have a pointer (stack_start) very close to the stack top, the
1275 // next thing to do is to figure out the exact location of stack top. We
1276 // can find out the virtual memory area that contains stack_start by
1277 // reading /proc/self/maps, it should be the last vma in /proc/self/maps,
1278 // and its upper limit is the real stack top. (again, this would fail if
1279 // running inside chroot, because /proc may not exist.)
1280
1281 uintptr_t stack_top;
1282 address low, high;
1283 if (find_vma((address)stack_start, &low, &high)) {
1284 // success, "high" is the true stack top. (ignore "low", because initial
1285 // thread stack grows on demand, its real bottom is high - RLIMIT_STACK.)
1286 stack_top = (uintptr_t)high;
1287 } else {
1288 // failed, likely because /proc/self/maps does not exist
1289 warning("Can't detect initial thread stack location - find_vma failed");
1290 // best effort: stack_start is normally within a few pages below the real
1291 // stack top, use it as stack top, and reduce stack size so we won't put
1292 // guard page outside stack.
1293 stack_top = stack_start;
1294 stack_size -= 16 * page_size();
1295 }
1296
1297 // stack_top could be partially down the page so align it
1298 stack_top = align_size_up(stack_top, page_size());
1299
1300 if (max_size && stack_size > max_size) {
1301 _initial_thread_stack_size = max_size;
1302 } else {
1303 _initial_thread_stack_size = stack_size;
1304 }
1305
1306 _initial_thread_stack_size = align_size_down(_initial_thread_stack_size, page_size());
1307 _initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size;
1308 }
1309
1310 ////////////////////////////////////////////////////////////////////////////////
1311 // time support
1312
1313 // Time since start-up in seconds to a fine granularity.
1314 // Used by VMSelfDestructTimer and the MemProfiler.
1315 double os::elapsedTime() {
1316
1317 return ((double)os::elapsed_counter()) / os::elapsed_frequency(); // nanosecond resolution
1318 }
1319
1320 jlong os::elapsed_counter() {
1321 return javaTimeNanos() - initial_time_count;
1322 }
1323
1324 jlong os::elapsed_frequency() {
1325 return NANOSECS_PER_SEC; // nanosecond resolution
1326 }
1327
1328 bool os::supports_vtime() { return true; }
1329 bool os::enable_vtime() { return false; }
1330 bool os::vtime_enabled() { return false; }
1331
1332 double os::elapsedVTime() {
1333 struct rusage usage;
1334 int retval = getrusage(RUSAGE_THREAD, &usage);
1335 if (retval == 0) {
1336 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);
1337 } else {
1338 // better than nothing, but not much
1339 return elapsedTime();
1340 }
1341 }
1342
1343 jlong os::javaTimeMillis() {
1344 timeval time;
1345 int status = gettimeofday(&time, NULL);
1346 assert(status != -1, "linux error");
1347 return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000);
1348 }
1349
1350 #ifndef CLOCK_MONOTONIC
1351 #define CLOCK_MONOTONIC (1)
1352 #endif
1353
1354 void os::Linux::clock_init() {
1355 // we do dlopen's in this particular order due to bug in linux
1356 // dynamical loader (see 6348968) leading to crash on exit
1357 void* handle = dlopen("librt.so.1", RTLD_LAZY);
1358 if (handle == NULL) {
1359 handle = dlopen("librt.so", RTLD_LAZY);
1360 }
1361
1362 if (handle) {
1363 int (*clock_getres_func)(clockid_t, struct timespec*) =
1364 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres");
1365 int (*clock_gettime_func)(clockid_t, struct timespec*) =
1366 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime");
1367 if (clock_getres_func && clock_gettime_func) {
1368 // See if monotonic clock is supported by the kernel. Note that some
1369 // early implementations simply return kernel jiffies (updated every
1370 // 1/100 or 1/1000 second). It would be bad to use such a low res clock
1371 // for nano time (though the monotonic property is still nice to have).
1372 // It's fixed in newer kernels, however clock_getres() still returns
1373 // 1/HZ. We check if clock_getres() works, but will ignore its reported
1374 // resolution for now. Hopefully as people move to new kernels, this
1375 // won't be a problem.
1376 struct timespec res;
1377 struct timespec tp;
1378 if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 &&
1379 clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) {
1380 // yes, monotonic clock is supported
1381 _clock_gettime = clock_gettime_func;
1382 return;
1383 } else {
1384 // close librt if there is no monotonic clock
1385 dlclose(handle);
1386 }
1387 }
1388 }
1389 warning("No monotonic clock was available - timed services may " \
1390 "be adversely affected if the time-of-day clock changes");
1391 }
1392
1393 #ifndef SYS_clock_getres
1394
1395 #if defined(IA32) || defined(AMD64)
1396 #define SYS_clock_getres IA32_ONLY(266) AMD64_ONLY(229)
1397 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y)
1398 #else
1399 #warning "SYS_clock_getres not defined for this platform, disabling fast_thread_cpu_time"
1400 #define sys_clock_getres(x,y) -1
1401 #endif
1402
1403 #else
1404 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y)
1405 #endif
1406
1407 void os::Linux::fast_thread_clock_init() {
1408 if (!UseLinuxPosixThreadCPUClocks) {
1409 return;
1410 }
1411 clockid_t clockid;
1412 struct timespec tp;
1413 int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) =
1414 (int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid");
1415
1416 // Switch to using fast clocks for thread cpu time if
1417 // the sys_clock_getres() returns 0 error code.
1418 // Note, that some kernels may support the current thread
1419 // clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks
1420 // returned by the pthread_getcpuclockid().
1421 // If the fast Posix clocks are supported then the sys_clock_getres()
1422 // must return at least tp.tv_sec == 0 which means a resolution
1423 // better than 1 sec. This is extra check for reliability.
1424
1425 if (pthread_getcpuclockid_func &&
1426 pthread_getcpuclockid_func(_main_thread, &clockid) == 0 &&
1427 sys_clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) {
1428
1429 _supports_fast_thread_cpu_time = true;
1430 _pthread_getcpuclockid = pthread_getcpuclockid_func;
1431 }
1432 }
1433
1434 jlong os::javaTimeNanos() {
1435 if (os::supports_monotonic_clock()) {
1436 struct timespec tp;
1437 int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp);
1438 assert(status == 0, "gettime error");
1439 jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec);
1440 return result;
1441 } else {
1442 timeval time;
1443 int status = gettimeofday(&time, NULL);
1444 assert(status != -1, "linux error");
1445 jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec);
1446 return 1000 * usecs;
1447 }
1448 }
1449
1450 void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) {
1451 if (os::supports_monotonic_clock()) {
1452 info_ptr->max_value = ALL_64_BITS;
1453
1454 // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past
1455 info_ptr->may_skip_backward = false; // not subject to resetting or drifting
1456 info_ptr->may_skip_forward = false; // not subject to resetting or drifting
1457 } else {
1458 // gettimeofday - based on time in seconds since the Epoch thus does not wrap
1459 info_ptr->max_value = ALL_64_BITS;
1460
1461 // gettimeofday is a real time clock so it skips
1462 info_ptr->may_skip_backward = true;
1463 info_ptr->may_skip_forward = true;
1464 }
1465
1466 info_ptr->kind = JVMTI_TIMER_ELAPSED; // elapsed not CPU time
1467 }
1468
1469 // Return the real, user, and system times in seconds from an
1470 // arbitrary fixed point in the past.
1471 bool os::getTimesSecs(double* process_real_time,
1472 double* process_user_time,
1473 double* process_system_time) {
1474 struct tms ticks;
1475 clock_t real_ticks = times(&ticks);
1476
1477 if (real_ticks == (clock_t) (-1)) {
1478 return false;
1479 } else {
1480 double ticks_per_second = (double) clock_tics_per_sec;
1481 *process_user_time = ((double) ticks.tms_utime) / ticks_per_second;
1482 *process_system_time = ((double) ticks.tms_stime) / ticks_per_second;
1483 *process_real_time = ((double) real_ticks) / ticks_per_second;
1484
1485 return true;
1486 }
1487 }
1488
1489
1490 char * os::local_time_string(char *buf, size_t buflen) {
1491 struct tm t;
1492 time_t long_time;
1493 time(&long_time);
1494 localtime_r(&long_time, &t);
1495 jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d",
1496 t.tm_year + 1900, t.tm_mon + 1, t.tm_mday,
1497 t.tm_hour, t.tm_min, t.tm_sec);
1498 return buf;
1499 }
1500
1501 struct tm* os::localtime_pd(const time_t* clock, struct tm* res) {
1502 return localtime_r(clock, res);
1503 }
1504
1505 ////////////////////////////////////////////////////////////////////////////////
1506 // runtime exit support
1507
1508 // Note: os::shutdown() might be called very early during initialization, or
1509 // called from signal handler. Before adding something to os::shutdown(), make
1510 // sure it is async-safe and can handle partially initialized VM.
1511 void os::shutdown() {
1512
1513 // allow PerfMemory to attempt cleanup of any persistent resources
1514 perfMemory_exit();
1515
1516 // needs to remove object in file system
1517 AttachListener::abort();
1518
1519 // flush buffered output, finish log files
1520 ostream_abort();
1521
1522 // Check for abort hook
1523 abort_hook_t abort_hook = Arguments::abort_hook();
1524 if (abort_hook != NULL) {
1525 abort_hook();
1526 }
1527
1528 }
1529
1530 // Note: os::abort() might be called very early during initialization, or
1531 // called from signal handler. Before adding something to os::abort(), make
1532 // sure it is async-safe and can handle partially initialized VM.
1533 void os::abort(bool dump_core) {
1534 os::shutdown();
1535 if (dump_core) {
1536 #ifndef PRODUCT
1537 fdStream out(defaultStream::output_fd());
1538 out.print_raw("Current thread is ");
1539 char buf[16];
1540 jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id());
1541 out.print_raw_cr(buf);
1542 out.print_raw_cr("Dumping core ...");
1543 #endif
1544 ::abort(); // dump core
1545 }
1546
1547 ::exit(1);
1548 }
1549
1550 // Die immediately, no exit hook, no abort hook, no cleanup.
1551 void os::die() {
1552 // _exit() on LinuxThreads only kills current thread
1553 ::abort();
1554 }
1555
1556
1557 // This method is a copy of JDK's sysGetLastErrorString
1558 // from src/solaris/hpi/src/system_md.c
1559
1560 size_t os::lasterror(char *buf, size_t len) {
1561
1562 if (errno == 0) return 0;
1563
1564 const char *s = ::strerror(errno);
1565 size_t n = ::strlen(s);
1566 if (n >= len) {
1567 n = len - 1;
1568 }
1569 ::strncpy(buf, s, n);
1570 buf[n] = '\0';
1571 return n;
1572 }
1573
1574 intx os::current_thread_id() { return (intx)pthread_self(); }
1575 int os::current_process_id() {
1576
1577 // Under the old linux thread library, linux gives each thread
1578 // its own process id. Because of this each thread will return
1579 // a different pid if this method were to return the result
1580 // of getpid(2). Linux provides no api that returns the pid
1581 // of the launcher thread for the vm. This implementation
1582 // returns a unique pid, the pid of the launcher thread
1583 // that starts the vm 'process'.
1584
1585 // Under the NPTL, getpid() returns the same pid as the
1586 // launcher thread rather than a unique pid per thread.
1587 // Use gettid() if you want the old pre NPTL behaviour.
1588
1589 // if you are looking for the result of a call to getpid() that
1590 // returns a unique pid for the calling thread, then look at the
1591 // OSThread::thread_id() method in osThread_linux.hpp file
1592
1593 return (int)(_initial_pid ? _initial_pid : getpid());
1594 }
1595
1596 // DLL functions
1597
1598 const char* os::dll_file_extension() { return ".so"; }
1599
1600 // This must be hard coded because it's the system's temporary
1601 // directory not the java application's temp directory, ala java.io.tmpdir.
1602 const char* os::get_temp_directory() { return "/tmp"; }
1603
1604 static bool file_exists(const char* filename) {
1605 struct stat statbuf;
1606 if (filename == NULL || strlen(filename) == 0) {
1607 return false;
1608 }
1609 return os::stat(filename, &statbuf) == 0;
1610 }
1611
1612 bool os::dll_build_name(char* buffer, size_t buflen,
1613 const char* pname, const char* fname) {
1614 bool retval = false;
1615 // Copied from libhpi
1616 const size_t pnamelen = pname ? strlen(pname) : 0;
1617
1618 // Return error on buffer overflow.
1619 if (pnamelen + strlen(fname) + 10 > (size_t) buflen) {
1620 return retval;
1621 }
1622
1623 if (pnamelen == 0) {
1624 snprintf(buffer, buflen, "lib%s.so", fname);
1625 retval = true;
1626 } else if (strchr(pname, *os::path_separator()) != NULL) {
1627 int n;
1628 char** pelements = split_path(pname, &n);
1629 if (pelements == NULL) {
1630 return false;
1631 }
1632 for (int i = 0; i < n; i++) {
1633 // Really shouldn't be NULL, but check can't hurt
1634 if (pelements[i] == NULL || strlen(pelements[i]) == 0) {
1635 continue; // skip the empty path values
1636 }
1637 snprintf(buffer, buflen, "%s/lib%s.so", pelements[i], fname);
1638 if (file_exists(buffer)) {
1639 retval = true;
1640 break;
1641 }
1642 }
1643 // release the storage
1644 for (int i = 0; i < n; i++) {
1645 if (pelements[i] != NULL) {
1646 FREE_C_HEAP_ARRAY(char, pelements[i], mtInternal);
1647 }
1648 }
1649 if (pelements != NULL) {
1650 FREE_C_HEAP_ARRAY(char*, pelements, mtInternal);
1651 }
1652 } else {
1653 snprintf(buffer, buflen, "%s/lib%s.so", pname, fname);
1654 retval = true;
1655 }
1656 return retval;
1657 }
1658
1659 // check if addr is inside libjvm.so
1660 bool os::address_is_in_vm(address addr) {
1661 static address libjvm_base_addr;
1662 Dl_info dlinfo;
1663
1664 if (libjvm_base_addr == NULL) {
1665 if (dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo) != 0) {
1666 libjvm_base_addr = (address)dlinfo.dli_fbase;
1667 }
1668 assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm");
1669 }
1670
1671 if (dladdr((void *)addr, &dlinfo) != 0) {
1672 if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true;
1673 }
1674
1675 return false;
1676 }
1677
1678 bool os::dll_address_to_function_name(address addr, char *buf,
1679 int buflen, int *offset) {
1680 // buf is not optional, but offset is optional
1681 assert(buf != NULL, "sanity check");
1682
1683 Dl_info dlinfo;
1684
1685 if (dladdr((void*)addr, &dlinfo) != 0) {
1686 // see if we have a matching symbol
1687 if (dlinfo.dli_saddr != NULL && dlinfo.dli_sname != NULL) {
1688 if (!Decoder::demangle(dlinfo.dli_sname, buf, buflen)) {
1689 jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname);
1690 }
1691 if (offset != NULL) *offset = addr - (address)dlinfo.dli_saddr;
1692 return true;
1693 }
1694 // no matching symbol so try for just file info
1695 if (dlinfo.dli_fname != NULL && dlinfo.dli_fbase != NULL) {
1696 if (Decoder::decode((address)(addr - (address)dlinfo.dli_fbase),
1697 buf, buflen, offset, dlinfo.dli_fname)) {
1698 return true;
1699 }
1700 }
1701 }
1702
1703 buf[0] = '\0';
1704 if (offset != NULL) *offset = -1;
1705 return false;
1706 }
1707
1708 struct _address_to_library_name {
1709 address addr; // input : memory address
1710 size_t buflen; // size of fname
1711 char* fname; // output: library name
1712 address base; // library base addr
1713 };
1714
1715 static int address_to_library_name_callback(struct dl_phdr_info *info,
1716 size_t size, void *data) {
1717 int i;
1718 bool found = false;
1719 address libbase = NULL;
1720 struct _address_to_library_name * d = (struct _address_to_library_name *)data;
1721
1722 // iterate through all loadable segments
1723 for (i = 0; i < info->dlpi_phnum; i++) {
1724 address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr);
1725 if (info->dlpi_phdr[i].p_type == PT_LOAD) {
1726 // base address of a library is the lowest address of its loaded
1727 // segments.
1728 if (libbase == NULL || libbase > segbase) {
1729 libbase = segbase;
1730 }
1731 // see if 'addr' is within current segment
1732 if (segbase <= d->addr &&
1733 d->addr < segbase + info->dlpi_phdr[i].p_memsz) {
1734 found = true;
1735 }
1736 }
1737 }
1738
1739 // dlpi_name is NULL or empty if the ELF file is executable, return 0
1740 // so dll_address_to_library_name() can fall through to use dladdr() which
1741 // can figure out executable name from argv[0].
1742 if (found && info->dlpi_name && info->dlpi_name[0]) {
1743 d->base = libbase;
1744 if (d->fname) {
1745 jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name);
1746 }
1747 return 1;
1748 }
1749 return 0;
1750 }
1751
1752 bool os::dll_address_to_library_name(address addr, char* buf,
1753 int buflen, int* offset) {
1754 // buf is not optional, but offset is optional
1755 assert(buf != NULL, "sanity check");
1756
1757 Dl_info dlinfo;
1758 struct _address_to_library_name data;
1759
1760 // There is a bug in old glibc dladdr() implementation that it could resolve
1761 // to wrong library name if the .so file has a base address != NULL. Here
1762 // we iterate through the program headers of all loaded libraries to find
1763 // out which library 'addr' really belongs to. This workaround can be
1764 // removed once the minimum requirement for glibc is moved to 2.3.x.
1765 data.addr = addr;
1766 data.fname = buf;
1767 data.buflen = buflen;
1768 data.base = NULL;
1769 int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data);
1770
1771 if (rslt) {
1772 // buf already contains library name
1773 if (offset) *offset = addr - data.base;
1774 return true;
1775 }
1776 if (dladdr((void*)addr, &dlinfo) != 0) {
1777 if (dlinfo.dli_fname != NULL) {
1778 jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname);
1779 }
1780 if (dlinfo.dli_fbase != NULL && offset != NULL) {
1781 *offset = addr - (address)dlinfo.dli_fbase;
1782 }
1783 return true;
1784 }
1785
1786 buf[0] = '\0';
1787 if (offset) *offset = -1;
1788 return false;
1789 }
1790
1791 // Loads .dll/.so and
1792 // in case of error it checks if .dll/.so was built for the
1793 // same architecture as Hotspot is running on
1794
1795
1796 // Remember the stack's state. The Linux dynamic linker will change
1797 // the stack to 'executable' at most once, so we must safepoint only once.
1798 bool os::Linux::_stack_is_executable = false;
1799
1800 // VM operation that loads a library. This is necessary if stack protection
1801 // of the Java stacks can be lost during loading the library. If we
1802 // do not stop the Java threads, they can stack overflow before the stacks
1803 // are protected again.
1804 class VM_LinuxDllLoad: public VM_Operation {
1805 private:
1806 const char *_filename;
1807 char *_ebuf;
1808 int _ebuflen;
1809 void *_lib;
1810 public:
1811 VM_LinuxDllLoad(const char *fn, char *ebuf, int ebuflen) :
1812 _filename(fn), _ebuf(ebuf), _ebuflen(ebuflen), _lib(NULL) {}
1813 VMOp_Type type() const { return VMOp_LinuxDllLoad; }
1814 void doit() {
1815 _lib = os::Linux::dll_load_in_vmthread(_filename, _ebuf, _ebuflen);
1816 os::Linux::_stack_is_executable = true;
1817 }
1818 void* loaded_library() { return _lib; }
1819 };
1820
1821 void * os::dll_load(const char *filename, char *ebuf, int ebuflen)
1822 {
1823 void * result = NULL;
1824 bool load_attempted = false;
1825
1826 // Check whether the library to load might change execution rights
1827 // of the stack. If they are changed, the protection of the stack
1828 // guard pages will be lost. We need a safepoint to fix this.
1829 //
1830 // See Linux man page execstack(8) for more info.
1831 if (os::uses_stack_guard_pages() && !os::Linux::_stack_is_executable) {
1832 ElfFile ef(filename);
1833 if (!ef.specifies_noexecstack()) {
1834 if (!is_init_completed()) {
1835 os::Linux::_stack_is_executable = true;
1836 // This is OK - No Java threads have been created yet, and hence no
1837 // stack guard pages to fix.
1838 //
1839 // This should happen only when you are building JDK7 using a very
1840 // old version of JDK6 (e.g., with JPRT) and running test_gamma.
1841 //
1842 // Dynamic loader will make all stacks executable after
1843 // this function returns, and will not do that again.
1844 assert(Threads::first() == NULL, "no Java threads should exist yet.");
1845 } else {
1846 warning("You have loaded library %s which might have disabled stack guard. "
1847 "The VM will try to fix the stack guard now.\n"
1848 "It's highly recommended that you fix the library with "
1849 "'execstack -c <libfile>', or link it with '-z noexecstack'.",
1850 filename);
1851
1852 assert(Thread::current()->is_Java_thread(), "must be Java thread");
1853 JavaThread *jt = JavaThread::current();
1854 if (jt->thread_state() != _thread_in_native) {
1855 // This happens when a compiler thread tries to load a hsdis-<arch>.so file
1856 // that requires ExecStack. Cannot enter safe point. Let's give up.
1857 warning("Unable to fix stack guard. Giving up.");
1858 } else {
1859 if (!LoadExecStackDllInVMThread) {
1860 // This is for the case where the DLL has an static
1861 // constructor function that executes JNI code. We cannot
1862 // load such DLLs in the VMThread.
1863 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen);
1864 }
1865
1866 ThreadInVMfromNative tiv(jt);
1867 debug_only(VMNativeEntryWrapper vew;)
1868
1869 VM_LinuxDllLoad op(filename, ebuf, ebuflen);
1870 VMThread::execute(&op);
1871 if (LoadExecStackDllInVMThread) {
1872 result = op.loaded_library();
1873 }
1874 load_attempted = true;
1875 }
1876 }
1877 }
1878 }
1879
1880 if (!load_attempted) {
1881 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen);
1882 }
1883
1884 if (result != NULL) {
1885 // Successful loading
1886 return result;
1887 }
1888
1889 Elf32_Ehdr elf_head;
1890 int diag_msg_max_length=ebuflen-strlen(ebuf);
1891 char* diag_msg_buf=ebuf+strlen(ebuf);
1892
1893 if (diag_msg_max_length==0) {
1894 // No more space in ebuf for additional diagnostics message
1895 return NULL;
1896 }
1897
1898
1899 int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK);
1900
1901 if (file_descriptor < 0) {
1902 // Can't open library, report dlerror() message
1903 return NULL;
1904 }
1905
1906 bool failed_to_read_elf_head=
1907 (sizeof(elf_head)!=
1908 (::read(file_descriptor, &elf_head,sizeof(elf_head))));
1909
1910 ::close(file_descriptor);
1911 if (failed_to_read_elf_head) {
1912 // file i/o error - report dlerror() msg
1913 return NULL;
1914 }
1915
1916 typedef struct {
1917 Elf32_Half code; // Actual value as defined in elf.h
1918 Elf32_Half compat_class; // Compatibility of archs at VM's sense
1919 char elf_class; // 32 or 64 bit
1920 char endianess; // MSB or LSB
1921 char* name; // String representation
1922 } arch_t;
1923
1924 #ifndef EM_486
1925 #define EM_486 6 /* Intel 80486 */
1926 #endif
1927
1928 static const arch_t arch_array[]={
1929 {EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
1930 {EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
1931 {EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"},
1932 {EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"},
1933 {EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
1934 {EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
1935 {EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"},
1936 {EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"},
1937 #if defined(VM_LITTLE_ENDIAN)
1938 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2LSB, (char*)"Power PC 64"},
1939 #else
1940 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"},
1941 #endif
1942 {EM_ARM, EM_ARM, ELFCLASS32, ELFDATA2LSB, (char*)"ARM"},
1943 {EM_S390, EM_S390, ELFCLASSNONE, ELFDATA2MSB, (char*)"IBM System/390"},
1944 {EM_ALPHA, EM_ALPHA, ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"},
1945 {EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"},
1946 {EM_MIPS, EM_MIPS, ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"},
1947 {EM_PARISC, EM_PARISC, ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"},
1948 {EM_68K, EM_68K, ELFCLASS32, ELFDATA2MSB, (char*)"M68k"}
1949 };
1950
1951 #if (defined IA32)
1952 static Elf32_Half running_arch_code=EM_386;
1953 #elif (defined AMD64)
1954 static Elf32_Half running_arch_code=EM_X86_64;
1955 #elif (defined IA64)
1956 static Elf32_Half running_arch_code=EM_IA_64;
1957 #elif (defined __sparc) && (defined _LP64)
1958 static Elf32_Half running_arch_code=EM_SPARCV9;
1959 #elif (defined __sparc) && (!defined _LP64)
1960 static Elf32_Half running_arch_code=EM_SPARC;
1961 #elif (defined __powerpc64__)
1962 static Elf32_Half running_arch_code=EM_PPC64;
1963 #elif (defined __powerpc__)
1964 static Elf32_Half running_arch_code=EM_PPC;
1965 #elif (defined ARM)
1966 static Elf32_Half running_arch_code=EM_ARM;
1967 #elif (defined S390)
1968 static Elf32_Half running_arch_code=EM_S390;
1969 #elif (defined ALPHA)
1970 static Elf32_Half running_arch_code=EM_ALPHA;
1971 #elif (defined MIPSEL)
1972 static Elf32_Half running_arch_code=EM_MIPS_RS3_LE;
1973 #elif (defined PARISC)
1974 static Elf32_Half running_arch_code=EM_PARISC;
1975 #elif (defined MIPS)
1976 static Elf32_Half running_arch_code=EM_MIPS;
1977 #elif (defined M68K)
1978 static Elf32_Half running_arch_code=EM_68K;
1979 #else
1980 #error Method os::dll_load requires that one of following is defined:\
1981 IA32, AMD64, IA64, __sparc, __powerpc__, ARM, S390, ALPHA, MIPS, MIPSEL, PARISC, M68K
1982 #endif
1983
1984 // Identify compatability class for VM's architecture and library's architecture
1985 // Obtain string descriptions for architectures
1986
1987 arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL};
1988 int running_arch_index=-1;
1989
1990 for (unsigned int i=0; i < ARRAY_SIZE(arch_array); i++) {
1991 if (running_arch_code == arch_array[i].code) {
1992 running_arch_index = i;
1993 }
1994 if (lib_arch.code == arch_array[i].code) {
1995 lib_arch.compat_class = arch_array[i].compat_class;
1996 lib_arch.name = arch_array[i].name;
1997 }
1998 }
1999
2000 assert(running_arch_index != -1,
2001 "Didn't find running architecture code (running_arch_code) in arch_array");
2002 if (running_arch_index == -1) {
2003 // Even though running architecture detection failed
2004 // we may still continue with reporting dlerror() message
2005 return NULL;
2006 }
2007
2008 if (lib_arch.endianess != arch_array[running_arch_index].endianess) {
2009 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)");
2010 return NULL;
2011 }
2012
2013 #ifndef S390
2014 if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) {
2015 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)");
2016 return NULL;
2017 }
2018 #endif // !S390
2019
2020 if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) {
2021 if (lib_arch.name!=NULL) {
2022 ::snprintf(diag_msg_buf, diag_msg_max_length-1,
2023 " (Possible cause: can't load %s-bit .so on a %s-bit platform)",
2024 lib_arch.name, arch_array[running_arch_index].name);
2025 } else {
2026 ::snprintf(diag_msg_buf, diag_msg_max_length-1,
2027 " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)",
2028 lib_arch.code,
2029 arch_array[running_arch_index].name);
2030 }
2031 }
2032
2033 return NULL;
2034 }
2035
2036 void * os::Linux::dlopen_helper(const char *filename, char *ebuf, int ebuflen) {
2037 void * result = ::dlopen(filename, RTLD_LAZY);
2038 if (result == NULL) {
2039 ::strncpy(ebuf, ::dlerror(), ebuflen - 1);
2040 ebuf[ebuflen-1] = '\0';
2041 }
2042 return result;
2043 }
2044
2045 void * os::Linux::dll_load_in_vmthread(const char *filename, char *ebuf, int ebuflen) {
2046 void * result = NULL;
2047 if (LoadExecStackDllInVMThread) {
2048 result = dlopen_helper(filename, ebuf, ebuflen);
2049 }
2050
2051 // Since 7019808, libjvm.so is linked with -noexecstack. If the VM loads a
2052 // library that requires an executable stack, or which does not have this
2053 // stack attribute set, dlopen changes the stack attribute to executable. The
2054 // read protection of the guard pages gets lost.
2055 //
2056 // Need to check _stack_is_executable again as multiple VM_LinuxDllLoad
2057 // may have been queued at the same time.
2058
2059 if (!_stack_is_executable) {
2060 JavaThread *jt = Threads::first();
2061
2062 while (jt) {
2063 if (!jt->stack_guard_zone_unused() && // Stack not yet fully initialized
2064 jt->stack_yellow_zone_enabled()) { // No pending stack overflow exceptions
2065 if (!os::guard_memory((char *) jt->stack_red_zone_base() - jt->stack_red_zone_size(),
2066 jt->stack_yellow_zone_size() + jt->stack_red_zone_size())) {
2067 warning("Attempt to reguard stack yellow zone failed.");
2068 }
2069 }
2070 jt = jt->next();
2071 }
2072 }
2073
2074 return result;
2075 }
2076
2077 /*
2078 * glibc-2.0 libdl is not MT safe. If you are building with any glibc,
2079 * chances are you might want to run the generated bits against glibc-2.0
2080 * libdl.so, so always use locking for any version of glibc.
2081 */
2082 void* os::dll_lookup(void* handle, const char* name) {
2083 pthread_mutex_lock(&dl_mutex);
2084 void* res = dlsym(handle, name);
2085 pthread_mutex_unlock(&dl_mutex);
2086 return res;
2087 }
2088
2089 void* os::get_default_process_handle() {
2090 return (void*)::dlopen(NULL, RTLD_LAZY);
2091 }
2092
2093 static bool _print_ascii_file(const char* filename, outputStream* st) {
2094 int fd = ::open(filename, O_RDONLY);
2095 if (fd == -1) {
2096 return false;
2097 }
2098
2099 char buf[32];
2100 int bytes;
2101 while ((bytes = ::read(fd, buf, sizeof(buf))) > 0) {
2102 st->print_raw(buf, bytes);
2103 }
2104
2105 ::close(fd);
2106
2107 return true;
2108 }
2109
2110 void os::print_dll_info(outputStream *st) {
2111 st->print_cr("Dynamic libraries:");
2112
2113 char fname[32];
2114 pid_t pid = os::Linux::gettid();
2115
2116 jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid);
2117
2118 if (!_print_ascii_file(fname, st)) {
2119 st->print("Can not get library information for pid = %d\n", pid);
2120 }
2121 }
2122
2123 void os::print_os_info_brief(outputStream* st) {
2124 os::Linux::print_distro_info(st);
2125
2126 os::Posix::print_uname_info(st);
2127
2128 os::Linux::print_libversion_info(st);
2129
2130 }
2131
2132 void os::print_os_info(outputStream* st) {
2133 st->print("OS:");
2134
2135 os::Linux::print_distro_info(st);
2136
2137 os::Posix::print_uname_info(st);
2138
2139 // Print warning if unsafe chroot environment detected
2140 if (unsafe_chroot_detected) {
2141 st->print("WARNING!! ");
2142 st->print_cr("%s", unstable_chroot_error);
2143 }
2144
2145 os::Linux::print_libversion_info(st);
2146
2147 os::Posix::print_rlimit_info(st);
2148
2149 os::Posix::print_load_average(st);
2150
2151 os::Linux::print_full_memory_info(st);
2152 }
2153
2154 // Try to identify popular distros.
2155 // Most Linux distributions have a /etc/XXX-release file, which contains
2156 // the OS version string. Newer Linux distributions have a /etc/lsb-release
2157 // file that also contains the OS version string. Some have more than one
2158 // /etc/XXX-release file (e.g. Mandrake has both /etc/mandrake-release and
2159 // /etc/redhat-release.), so the order is important.
2160 // Any Linux that is based on Redhat (i.e. Oracle, Mandrake, Sun JDS...) have
2161 // their own specific XXX-release file as well as a redhat-release file.
2162 // Because of this the XXX-release file needs to be searched for before the
2163 // redhat-release file.
2164 // Since Red Hat has a lsb-release file that is not very descriptive the
2165 // search for redhat-release needs to be before lsb-release.
2166 // Since the lsb-release file is the new standard it needs to be searched
2167 // before the older style release files.
2168 // Searching system-release (Red Hat) and os-release (other Linuxes) are a
2169 // next to last resort. The os-release file is a new standard that contains
2170 // distribution information and the system-release file seems to be an old
2171 // standard that has been replaced by the lsb-release and os-release files.
2172 // Searching for the debian_version file is the last resort. It contains
2173 // an informative string like "6.0.6" or "wheezy/sid". Because of this
2174 // "Debian " is printed before the contents of the debian_version file.
2175 void os::Linux::print_distro_info(outputStream* st) {
2176 if (!_print_ascii_file("/etc/oracle-release", st) &&
2177 !_print_ascii_file("/etc/mandriva-release", st) &&
2178 !_print_ascii_file("/etc/mandrake-release", st) &&
2179 !_print_ascii_file("/etc/sun-release", st) &&
2180 !_print_ascii_file("/etc/redhat-release", st) &&
2181 !_print_ascii_file("/etc/lsb-release", st) &&
2182 !_print_ascii_file("/etc/SuSE-release", st) &&
2183 !_print_ascii_file("/etc/turbolinux-release", st) &&
2184 !_print_ascii_file("/etc/gentoo-release", st) &&
2185 !_print_ascii_file("/etc/ltib-release", st) &&
2186 !_print_ascii_file("/etc/angstrom-version", st) &&
2187 !_print_ascii_file("/etc/system-release", st) &&
2188 !_print_ascii_file("/etc/os-release", st)) {
2189
2190 if (file_exists("/etc/debian_version")) {
2191 st->print("Debian ");
2192 _print_ascii_file("/etc/debian_version", st);
2193 } else {
2194 st->print("Linux");
2195 }
2196 }
2197 st->cr();
2198 }
2199
2200 void os::Linux::print_libversion_info(outputStream* st) {
2201 // libc, pthread
2202 st->print("libc:");
2203 st->print("%s ", os::Linux::glibc_version());
2204 st->print("%s ", os::Linux::libpthread_version());
2205 if (os::Linux::is_LinuxThreads()) {
2206 st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed");
2207 }
2208 st->cr();
2209 }
2210
2211 void os::Linux::print_full_memory_info(outputStream* st) {
2212 st->print("\n/proc/meminfo:\n");
2213 _print_ascii_file("/proc/meminfo", st);
2214 st->cr();
2215 }
2216
2217 void os::print_memory_info(outputStream* st) {
2218
2219 st->print("Memory:");
2220 st->print(" %dk page", os::vm_page_size()>>10);
2221
2222 // values in struct sysinfo are "unsigned long"
2223 struct sysinfo si;
2224 sysinfo(&si);
2225
2226 st->print(", physical " UINT64_FORMAT "k",
2227 os::physical_memory() >> 10);
2228 st->print("(" UINT64_FORMAT "k free)",
2229 os::available_memory() >> 10);
2230 st->print(", swap " UINT64_FORMAT "k",
2231 ((jlong)si.totalswap * si.mem_unit) >> 10);
2232 st->print("(" UINT64_FORMAT "k free)",
2233 ((jlong)si.freeswap * si.mem_unit) >> 10);
2234 st->cr();
2235 }
2236
2237 void os::pd_print_cpu_info(outputStream* st) {
2238 st->print("\n/proc/cpuinfo:\n");
2239 if (!_print_ascii_file("/proc/cpuinfo", st)) {
2240 st->print(" <Not Available>");
2241 }
2242 st->cr();
2243 }
2244
2245 void os::print_siginfo(outputStream* st, void* siginfo) {
2246 const siginfo_t* si = (const siginfo_t*)siginfo;
2247
2248 os::Posix::print_siginfo_brief(st, si);
2249 #if INCLUDE_CDS
2250 if (si && (si->si_signo == SIGBUS || si->si_signo == SIGSEGV) &&
2251 UseSharedSpaces) {
2252 FileMapInfo* mapinfo = FileMapInfo::current_info();
2253 if (mapinfo->is_in_shared_space(si->si_addr)) {
2254 st->print("\n\nError accessing class data sharing archive." \
2255 " Mapped file inaccessible during execution, " \
2256 " possible disk/network problem.");
2257 }
2258 }
2259 #endif
2260 st->cr();
2261 }
2262
2263
2264 static void print_signal_handler(outputStream* st, int sig,
2265 char* buf, size_t buflen);
2266
2267 void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) {
2268 st->print_cr("Signal Handlers:");
2269 print_signal_handler(st, SIGSEGV, buf, buflen);
2270 print_signal_handler(st, SIGBUS , buf, buflen);
2271 print_signal_handler(st, SIGFPE , buf, buflen);
2272 print_signal_handler(st, SIGPIPE, buf, buflen);
2273 print_signal_handler(st, SIGXFSZ, buf, buflen);
2274 print_signal_handler(st, SIGILL , buf, buflen);
2275 print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen);
2276 print_signal_handler(st, SR_signum, buf, buflen);
2277 print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen);
2278 print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen);
2279 print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen);
2280 print_signal_handler(st, BREAK_SIGNAL, buf, buflen);
2281 #if defined(PPC64)
2282 print_signal_handler(st, SIGTRAP, buf, buflen);
2283 #endif
2284 }
2285
2286 static char saved_jvm_path[MAXPATHLEN] = {0};
2287
2288 // Find the full path to the current module, libjvm.so
2289 void os::jvm_path(char *buf, jint buflen) {
2290 // Error checking.
2291 if (buflen < MAXPATHLEN) {
2292 assert(false, "must use a large-enough buffer");
2293 buf[0] = '\0';
2294 return;
2295 }
2296 // Lazy resolve the path to current module.
2297 if (saved_jvm_path[0] != 0) {
2298 strcpy(buf, saved_jvm_path);
2299 return;
2300 }
2301
2302 char dli_fname[MAXPATHLEN];
2303 bool ret = dll_address_to_library_name(
2304 CAST_FROM_FN_PTR(address, os::jvm_path),
2305 dli_fname, sizeof(dli_fname), NULL);
2306 assert(ret, "cannot locate libjvm");
2307 char *rp = NULL;
2308 if (ret && dli_fname[0] != '\0') {
2309 rp = realpath(dli_fname, buf);
2310 }
2311 if (rp == NULL)
2312 return;
2313
2314 if (Arguments::sun_java_launcher_is_altjvm()) {
2315 // Support for the java launcher's '-XXaltjvm=<path>' option. Typical
2316 // value for buf is "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so".
2317 // If "/jre/lib/" appears at the right place in the string, then
2318 // assume we are installed in a JDK and we're done. Otherwise, check
2319 // for a JAVA_HOME environment variable and fix up the path so it
2320 // looks like libjvm.so is installed there (append a fake suffix
2321 // hotspot/libjvm.so).
2322 const char *p = buf + strlen(buf) - 1;
2323 for (int count = 0; p > buf && count < 5; ++count) {
2324 for (--p; p > buf && *p != '/'; --p)
2325 /* empty */ ;
2326 }
2327
2328 if (strncmp(p, "/jre/lib/", 9) != 0) {
2329 // Look for JAVA_HOME in the environment.
2330 char* java_home_var = ::getenv("JAVA_HOME");
2331 if (java_home_var != NULL && java_home_var[0] != 0) {
2332 char* jrelib_p;
2333 int len;
2334
2335 // Check the current module name "libjvm.so".
2336 p = strrchr(buf, '/');
2337 assert(strstr(p, "/libjvm") == p, "invalid library name");
2338
2339 rp = realpath(java_home_var, buf);
2340 if (rp == NULL)
2341 return;
2342
2343 // determine if this is a legacy image or modules image
2344 // modules image doesn't have "jre" subdirectory
2345 len = strlen(buf);
2346 assert(len < buflen, "Ran out of buffer room");
2347 jrelib_p = buf + len;
2348 snprintf(jrelib_p, buflen-len, "/jre/lib/%s", cpu_arch);
2349 if (0 != access(buf, F_OK)) {
2350 snprintf(jrelib_p, buflen-len, "/lib/%s", cpu_arch);
2351 }
2352
2353 if (0 == access(buf, F_OK)) {
2354 // Use current module name "libjvm.so"
2355 len = strlen(buf);
2356 snprintf(buf + len, buflen-len, "/hotspot/libjvm.so");
2357 } else {
2358 // Go back to path of .so
2359 rp = realpath(dli_fname, buf);
2360 if (rp == NULL)
2361 return;
2362 }
2363 }
2364 }
2365 }
2366
2367 strncpy(saved_jvm_path, buf, MAXPATHLEN);
2368 }
2369
2370 void os::print_jni_name_prefix_on(outputStream* st, int args_size) {
2371 // no prefix required, not even "_"
2372 }
2373
2374 void os::print_jni_name_suffix_on(outputStream* st, int args_size) {
2375 // no suffix required
2376 }
2377
2378 ////////////////////////////////////////////////////////////////////////////////
2379 // sun.misc.Signal support
2380
2381 static volatile jint sigint_count = 0;
2382
2383 static void
2384 UserHandler(int sig, void *siginfo, void *context) {
2385 // 4511530 - sem_post is serialized and handled by the manager thread. When
2386 // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We
2387 // don't want to flood the manager thread with sem_post requests.
2388 if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1)
2389 return;
2390
2391 // Ctrl-C is pressed during error reporting, likely because the error
2392 // handler fails to abort. Let VM die immediately.
2393 if (sig == SIGINT && is_error_reported()) {
2394 os::die();
2395 }
2396
2397 os::signal_notify(sig);
2398 }
2399
2400 void* os::user_handler() {
2401 return CAST_FROM_FN_PTR(void*, UserHandler);
2402 }
2403
2404 class Semaphore : public StackObj {
2405 public:
2406 Semaphore();
2407 ~Semaphore();
2408 void signal();
2409 void wait();
2410 bool trywait();
2411 bool timedwait(unsigned int sec, int nsec);
2412 private:
2413 sem_t _semaphore;
2414 };
2415
2416 Semaphore::Semaphore() {
2417 sem_init(&_semaphore, 0, 0);
2418 }
2419
2420 Semaphore::~Semaphore() {
2421 sem_destroy(&_semaphore);
2422 }
2423
2424 void Semaphore::signal() {
2425 sem_post(&_semaphore);
2426 }
2427
2428 void Semaphore::wait() {
2429 sem_wait(&_semaphore);
2430 }
2431
2432 bool Semaphore::trywait() {
2433 return sem_trywait(&_semaphore) == 0;
2434 }
2435
2436 bool Semaphore::timedwait(unsigned int sec, int nsec) {
2437
2438 struct timespec ts;
2439 // Semaphore's are always associated with CLOCK_REALTIME
2440 os::Linux::clock_gettime(CLOCK_REALTIME, &ts);
2441 // see unpackTime for discussion on overflow checking
2442 if (sec >= MAX_SECS) {
2443 ts.tv_sec += MAX_SECS;
2444 ts.tv_nsec = 0;
2445 } else {
2446 ts.tv_sec += sec;
2447 ts.tv_nsec += nsec;
2448 if (ts.tv_nsec >= NANOSECS_PER_SEC) {
2449 ts.tv_nsec -= NANOSECS_PER_SEC;
2450 ++ts.tv_sec; // note: this must be <= max_secs
2451 }
2452 }
2453
2454 while (1) {
2455 int result = sem_timedwait(&_semaphore, &ts);
2456 if (result == 0) {
2457 return true;
2458 } else if (errno == EINTR) {
2459 continue;
2460 } else if (errno == ETIMEDOUT) {
2461 return false;
2462 } else {
2463 return false;
2464 }
2465 }
2466 }
2467
2468 extern "C" {
2469 typedef void (*sa_handler_t)(int);
2470 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *);
2471 }
2472
2473 void* os::signal(int signal_number, void* handler) {
2474 struct sigaction sigAct, oldSigAct;
2475
2476 sigfillset(&(sigAct.sa_mask));
2477 sigAct.sa_flags = SA_RESTART|SA_SIGINFO;
2478 sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler);
2479
2480 if (sigaction(signal_number, &sigAct, &oldSigAct)) {
2481 // -1 means registration failed
2482 return (void *)-1;
2483 }
2484
2485 return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler);
2486 }
2487
2488 void os::signal_raise(int signal_number) {
2489 ::raise(signal_number);
2490 }
2491
2492 /*
2493 * The following code is moved from os.cpp for making this
2494 * code platform specific, which it is by its very nature.
2495 */
2496
2497 // Will be modified when max signal is changed to be dynamic
2498 int os::sigexitnum_pd() {
2499 return NSIG;
2500 }
2501
2502 // a counter for each possible signal value
2503 static volatile jint pending_signals[NSIG+1] = { 0 };
2504
2505 // Linux(POSIX) specific hand shaking semaphore.
2506 static sem_t sig_sem;
2507 static Semaphore sr_semaphore;
2508
2509 void os::signal_init_pd() {
2510 // Initialize signal structures
2511 ::memset((void*)pending_signals, 0, sizeof(pending_signals));
2512
2513 // Initialize signal semaphore
2514 ::sem_init(&sig_sem, 0, 0);
2515 }
2516
2517 void os::signal_notify(int sig) {
2518 Atomic::inc(&pending_signals[sig]);
2519 ::sem_post(&sig_sem);
2520 }
2521
2522 static int check_pending_signals(bool wait) {
2523 Atomic::store(0, &sigint_count);
2524 for (;;) {
2525 for (int i = 0; i < NSIG + 1; i++) {
2526 jint n = pending_signals[i];
2527 if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) {
2528 return i;
2529 }
2530 }
2531 if (!wait) {
2532 return -1;
2533 }
2534 JavaThread *thread = JavaThread::current();
2535 ThreadBlockInVM tbivm(thread);
2536
2537 bool threadIsSuspended;
2538 do {
2539 thread->set_suspend_equivalent();
2540 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
2541 ::sem_wait(&sig_sem);
2542
2543 // were we externally suspended while we were waiting?
2544 threadIsSuspended = thread->handle_special_suspend_equivalent_condition();
2545 if (threadIsSuspended) {
2546 //
2547 // The semaphore has been incremented, but while we were waiting
2548 // another thread suspended us. We don't want to continue running
2549 // while suspended because that would surprise the thread that
2550 // suspended us.
2551 //
2552 ::sem_post(&sig_sem);
2553
2554 thread->java_suspend_self();
2555 }
2556 } while (threadIsSuspended);
2557 }
2558 }
2559
2560 int os::signal_lookup() {
2561 return check_pending_signals(false);
2562 }
2563
2564 int os::signal_wait() {
2565 return check_pending_signals(true);
2566 }
2567
2568 ////////////////////////////////////////////////////////////////////////////////
2569 // Virtual Memory
2570
2571 int os::vm_page_size() {
2572 // Seems redundant as all get out
2573 assert(os::Linux::page_size() != -1, "must call os::init");
2574 return os::Linux::page_size();
2575 }
2576
2577 // Solaris allocates memory by pages.
2578 int os::vm_allocation_granularity() {
2579 assert(os::Linux::page_size() != -1, "must call os::init");
2580 return os::Linux::page_size();
2581 }
2582
2583 // Rationale behind this function:
2584 // current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable
2585 // mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get
2586 // samples for JITted code. Here we create private executable mapping over the code cache
2587 // and then we can use standard (well, almost, as mapping can change) way to provide
2588 // info for the reporting script by storing timestamp and location of symbol
2589 void linux_wrap_code(char* base, size_t size) {
2590 static volatile jint cnt = 0;
2591
2592 if (!UseOprofile) {
2593 return;
2594 }
2595
2596 char buf[PATH_MAX+1];
2597 int num = Atomic::add(1, &cnt);
2598
2599 snprintf(buf, sizeof(buf), "%s/hs-vm-%d-%d",
2600 os::get_temp_directory(), os::current_process_id(), num);
2601 unlink(buf);
2602
2603 int fd = ::open(buf, O_CREAT | O_RDWR, S_IRWXU);
2604
2605 if (fd != -1) {
2606 off_t rv = ::lseek(fd, size-2, SEEK_SET);
2607 if (rv != (off_t)-1) {
2608 if (::write(fd, "", 1) == 1) {
2609 mmap(base, size,
2610 PROT_READ|PROT_WRITE|PROT_EXEC,
2611 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0);
2612 }
2613 }
2614 ::close(fd);
2615 unlink(buf);
2616 }
2617 }
2618
2619 static bool recoverable_mmap_error(int err) {
2620 // See if the error is one we can let the caller handle. This
2621 // list of errno values comes from JBS-6843484. I can't find a
2622 // Linux man page that documents this specific set of errno
2623 // values so while this list currently matches Solaris, it may
2624 // change as we gain experience with this failure mode.
2625 switch (err) {
2626 case EBADF:
2627 case EINVAL:
2628 case ENOTSUP:
2629 // let the caller deal with these errors
2630 return true;
2631
2632 default:
2633 // Any remaining errors on this OS can cause our reserved mapping
2634 // to be lost. That can cause confusion where different data
2635 // structures think they have the same memory mapped. The worst
2636 // scenario is if both the VM and a library think they have the
2637 // same memory mapped.
2638 return false;
2639 }
2640 }
2641
2642 static void warn_fail_commit_memory(char* addr, size_t size, bool exec,
2643 int err) {
2644 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT
2645 ", %d) failed; error='%s' (errno=%d)", addr, size, exec,
2646 strerror(err), err);
2647 }
2648
2649 static void warn_fail_commit_memory(char* addr, size_t size,
2650 size_t alignment_hint, bool exec,
2651 int err) {
2652 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT
2653 ", " SIZE_FORMAT ", %d) failed; error='%s' (errno=%d)", addr, size,
2654 alignment_hint, exec, strerror(err), err);
2655 }
2656
2657 // NOTE: Linux kernel does not really reserve the pages for us.
2658 // All it does is to check if there are enough free pages
2659 // left at the time of mmap(). This could be a potential
2660 // problem.
2661 int os::Linux::commit_memory_impl(char* addr, size_t size, bool exec) {
2662 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
2663 uintptr_t res = (uintptr_t) ::mmap(addr, size, prot,
2664 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0);
2665 if (res != (uintptr_t) MAP_FAILED) {
2666 if (UseNUMAInterleaving) {
2667 numa_make_global(addr, size);
2668 }
2669 return 0;
2670 }
2671
2672 int err = errno; // save errno from mmap() call above
2673
2674 if (!recoverable_mmap_error(err)) {
2675 warn_fail_commit_memory(addr, size, exec, err);
2676 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, "committing reserved memory.");
2677 }
2678
2679 return err;
2680 }
2681
2682 bool os::pd_commit_memory(char* addr, size_t size, bool exec) {
2683 return os::Linux::commit_memory_impl(addr, size, exec) == 0;
2684 }
2685
2686 void os::pd_commit_memory_or_exit(char* addr, size_t size, bool exec,
2687 const char* mesg) {
2688 assert(mesg != NULL, "mesg must be specified");
2689 int err = os::Linux::commit_memory_impl(addr, size, exec);
2690 if (err != 0) {
2691 // the caller wants all commit errors to exit with the specified mesg:
2692 warn_fail_commit_memory(addr, size, exec, err);
2693 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg);
2694 }
2695 }
2696
2697 // Define MAP_HUGETLB here so we can build HotSpot on old systems.
2698 #ifndef MAP_HUGETLB
2699 #define MAP_HUGETLB 0x40000
2700 #endif
2701
2702 // Define MADV_HUGEPAGE here so we can build HotSpot on old systems.
2703 #ifndef MADV_HUGEPAGE
2704 #define MADV_HUGEPAGE 14
2705 #endif
2706
2707 int os::Linux::commit_memory_impl(char* addr, size_t size,
2708 size_t alignment_hint, bool exec) {
2709 int err = os::Linux::commit_memory_impl(addr, size, exec);
2710 if (err == 0) {
2711 realign_memory(addr, size, alignment_hint);
2712 }
2713 return err;
2714 }
2715
2716 bool os::pd_commit_memory(char* addr, size_t size, size_t alignment_hint,
2717 bool exec) {
2718 return os::Linux::commit_memory_impl(addr, size, alignment_hint, exec) == 0;
2719 }
2720
2721 void os::pd_commit_memory_or_exit(char* addr, size_t size,
2722 size_t alignment_hint, bool exec,
2723 const char* mesg) {
2724 assert(mesg != NULL, "mesg must be specified");
2725 int err = os::Linux::commit_memory_impl(addr, size, alignment_hint, 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, alignment_hint, exec, err);
2729 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg);
2730 }
2731 }
2732
2733 void os::pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint) {
2734 if (UseTransparentHugePages && alignment_hint > (size_t)vm_page_size()) {
2735 // We don't check the return value: madvise(MADV_HUGEPAGE) may not
2736 // be supported or the memory may already be backed by huge pages.
2737 ::madvise(addr, bytes, MADV_HUGEPAGE);
2738 }
2739 }
2740
2741 void os::pd_free_memory(char *addr, size_t bytes, size_t alignment_hint) {
2742 // This method works by doing an mmap over an existing mmaping and effectively discarding
2743 // the existing pages. However it won't work for SHM-based large pages that cannot be
2744 // uncommitted at all. We don't do anything in this case to avoid creating a segment with
2745 // small pages on top of the SHM segment. This method always works for small pages, so we
2746 // allow that in any case.
2747 if (alignment_hint <= (size_t)os::vm_page_size() || can_commit_large_page_memory()) {
2748 commit_memory(addr, bytes, alignment_hint, !ExecMem);
2749 }
2750 }
2751
2752 void os::numa_make_global(char *addr, size_t bytes) {
2753 Linux::numa_interleave_memory(addr, bytes);
2754 }
2755
2756 // Define for numa_set_bind_policy(int). Setting the argument to 0 will set the
2757 // bind policy to MPOL_PREFERRED for the current thread.
2758 #define USE_MPOL_PREFERRED 0
2759
2760 void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) {
2761 // To make NUMA and large pages more robust when both enabled, we need to ease
2762 // the requirements on where the memory should be allocated. MPOL_BIND is the
2763 // default policy and it will force memory to be allocated on the specified
2764 // node. Changing this to MPOL_PREFERRED will prefer to allocate the memory on
2765 // the specified node, but will not force it. Using this policy will prevent
2766 // getting SIGBUS when trying to allocate large pages on NUMA nodes with no
2767 // free large pages.
2768 Linux::numa_set_bind_policy(USE_MPOL_PREFERRED);
2769 Linux::numa_tonode_memory(addr, bytes, lgrp_hint);
2770 }
2771
2772 bool os::numa_topology_changed() { return false; }
2773
2774 size_t os::numa_get_groups_num() {
2775 int max_node = Linux::numa_max_node();
2776 return max_node > 0 ? max_node + 1 : 1;
2777 }
2778
2779 int os::numa_get_group_id() {
2780 int cpu_id = Linux::sched_getcpu();
2781 if (cpu_id != -1) {
2782 int lgrp_id = Linux::get_node_by_cpu(cpu_id);
2783 if (lgrp_id != -1) {
2784 return lgrp_id;
2785 }
2786 }
2787 return 0;
2788 }
2789
2790 size_t os::numa_get_leaf_groups(int *ids, size_t size) {
2791 for (size_t i = 0; i < size; i++) {
2792 ids[i] = i;
2793 }
2794 return size;
2795 }
2796
2797 bool os::get_page_info(char *start, page_info* info) {
2798 return false;
2799 }
2800
2801 char *os::scan_pages(char *start, char* end, page_info* page_expected, page_info* page_found) {
2802 return end;
2803 }
2804
2805
2806 int os::Linux::sched_getcpu_syscall(void) {
2807 unsigned int cpu;
2808 int retval = -1;
2809
2810 #if defined(IA32)
2811 # ifndef SYS_getcpu
2812 # define SYS_getcpu 318
2813 # endif
2814 retval = syscall(SYS_getcpu, &cpu, NULL, NULL);
2815 #elif defined(AMD64)
2816 // Unfortunately we have to bring all these macros here from vsyscall.h
2817 // to be able to compile on old linuxes.
2818 # define __NR_vgetcpu 2
2819 # define VSYSCALL_START (-10UL << 20)
2820 # define VSYSCALL_SIZE 1024
2821 # define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr))
2822 typedef long (*vgetcpu_t)(unsigned int *cpu, unsigned int *node, unsigned long *tcache);
2823 vgetcpu_t vgetcpu = (vgetcpu_t)VSYSCALL_ADDR(__NR_vgetcpu);
2824 retval = vgetcpu(&cpu, NULL, NULL);
2825 #endif
2826
2827 return (retval == -1) ? retval : cpu;
2828 }
2829
2830 // Something to do with the numa-aware allocator needs these symbols
2831 extern "C" JNIEXPORT void numa_warn(int number, char *where, ...) { }
2832 extern "C" JNIEXPORT void numa_error(char *where) { }
2833 extern "C" JNIEXPORT int fork1() { return fork(); }
2834
2835
2836 // If we are running with libnuma version > 2, then we should
2837 // be trying to use symbols with versions 1.1
2838 // If we are running with earlier version, which did not have symbol versions,
2839 // we should use the base version.
2840 void* os::Linux::libnuma_dlsym(void* handle, const char *name) {
2841 void *f = dlvsym(handle, name, "libnuma_1.1");
2842 if (f == NULL) {
2843 f = dlsym(handle, name);
2844 }
2845 return f;
2846 }
2847
2848 bool os::Linux::libnuma_init() {
2849 // sched_getcpu() should be in libc.
2850 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t,
2851 dlsym(RTLD_DEFAULT, "sched_getcpu")));
2852
2853 // If it's not, try a direct syscall.
2854 if (sched_getcpu() == -1)
2855 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, (void*)&sched_getcpu_syscall));
2856
2857 if (sched_getcpu() != -1) { // Does it work?
2858 void *handle = dlopen("libnuma.so.1", RTLD_LAZY);
2859 if (handle != NULL) {
2860 set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t,
2861 libnuma_dlsym(handle, "numa_node_to_cpus")));
2862 set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t,
2863 libnuma_dlsym(handle, "numa_max_node")));
2864 set_numa_available(CAST_TO_FN_PTR(numa_available_func_t,
2865 libnuma_dlsym(handle, "numa_available")));
2866 set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t,
2867 libnuma_dlsym(handle, "numa_tonode_memory")));
2868 set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t,
2869 libnuma_dlsym(handle, "numa_interleave_memory")));
2870 set_numa_set_bind_policy(CAST_TO_FN_PTR(numa_set_bind_policy_func_t,
2871 libnuma_dlsym(handle, "numa_set_bind_policy")));
2872
2873
2874 if (numa_available() != -1) {
2875 set_numa_all_nodes((unsigned long*)libnuma_dlsym(handle, "numa_all_nodes"));
2876 // Create a cpu -> node mapping
2877 _cpu_to_node = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<int>(0, true);
2878 rebuild_cpu_to_node_map();
2879 return true;
2880 }
2881 }
2882 }
2883 return false;
2884 }
2885
2886 // rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id.
2887 // The table is later used in get_node_by_cpu().
2888 void os::Linux::rebuild_cpu_to_node_map() {
2889 const size_t NCPUS = 32768; // Since the buffer size computation is very obscure
2890 // in libnuma (possible values are starting from 16,
2891 // and continuing up with every other power of 2, but less
2892 // than the maximum number of CPUs supported by kernel), and
2893 // is a subject to change (in libnuma version 2 the requirements
2894 // are more reasonable) we'll just hardcode the number they use
2895 // in the library.
2896 const size_t BitsPerCLong = sizeof(long) * CHAR_BIT;
2897
2898 size_t cpu_num = os::active_processor_count();
2899 size_t cpu_map_size = NCPUS / BitsPerCLong;
2900 size_t cpu_map_valid_size =
2901 MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size);
2902
2903 cpu_to_node()->clear();
2904 cpu_to_node()->at_grow(cpu_num - 1);
2905 size_t node_num = numa_get_groups_num();
2906
2907 unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size, mtInternal);
2908 for (size_t i = 0; i < node_num; i++) {
2909 if (numa_node_to_cpus(i, cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) {
2910 for (size_t j = 0; j < cpu_map_valid_size; j++) {
2911 if (cpu_map[j] != 0) {
2912 for (size_t k = 0; k < BitsPerCLong; k++) {
2913 if (cpu_map[j] & (1UL << k)) {
2914 cpu_to_node()->at_put(j * BitsPerCLong + k, i);
2915 }
2916 }
2917 }
2918 }
2919 }
2920 }
2921 FREE_C_HEAP_ARRAY(unsigned long, cpu_map, mtInternal);
2922 }
2923
2924 int os::Linux::get_node_by_cpu(int cpu_id) {
2925 if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) {
2926 return cpu_to_node()->at(cpu_id);
2927 }
2928 return -1;
2929 }
2930
2931 GrowableArray<int>* os::Linux::_cpu_to_node;
2932 os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu;
2933 os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus;
2934 os::Linux::numa_max_node_func_t os::Linux::_numa_max_node;
2935 os::Linux::numa_available_func_t os::Linux::_numa_available;
2936 os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory;
2937 os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory;
2938 os::Linux::numa_set_bind_policy_func_t os::Linux::_numa_set_bind_policy;
2939 unsigned long* os::Linux::_numa_all_nodes;
2940
2941 bool os::pd_uncommit_memory(char* addr, size_t size) {
2942 uintptr_t res = (uintptr_t) ::mmap(addr, size, PROT_NONE,
2943 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0);
2944 return res != (uintptr_t) MAP_FAILED;
2945 }
2946
2947 static
2948 address get_stack_commited_bottom(address bottom, size_t size) {
2949 address nbot = bottom;
2950 address ntop = bottom + size;
2951
2952 size_t page_sz = os::vm_page_size();
2953 unsigned pages = size / page_sz;
2954
2955 unsigned char vec[1];
2956 unsigned imin = 1, imax = pages + 1, imid;
2957 int mincore_return_value = 0;
2958
2959 assert(imin <= imax, "Unexpected page size");
2960
2961 while (imin < imax) {
2962 imid = (imax + imin) / 2;
2963 nbot = ntop - (imid * page_sz);
2964
2965 // Use a trick with mincore to check whether the page is mapped or not.
2966 // mincore sets vec to 1 if page resides in memory and to 0 if page
2967 // is swapped output but if page we are asking for is unmapped
2968 // it returns -1,ENOMEM
2969 mincore_return_value = mincore(nbot, page_sz, vec);
2970
2971 if (mincore_return_value == -1) {
2972 // Page is not mapped go up
2973 // to find first mapped page
2974 if (errno != EAGAIN) {
2975 assert(errno == ENOMEM, "Unexpected mincore errno");
2976 imax = imid;
2977 }
2978 } else {
2979 // Page is mapped go down
2980 // to find first not mapped page
2981 imin = imid + 1;
2982 }
2983 }
2984
2985 nbot = nbot + page_sz;
2986
2987 // Adjust stack bottom one page up if last checked page is not mapped
2988 if (mincore_return_value == -1) {
2989 nbot = nbot + page_sz;
2990 }
2991
2992 return nbot;
2993 }
2994
2995
2996 // Linux uses a growable mapping for the stack, and if the mapping for
2997 // the stack guard pages is not removed when we detach a thread the
2998 // stack cannot grow beyond the pages where the stack guard was
2999 // mapped. If at some point later in the process the stack expands to
3000 // that point, the Linux kernel cannot expand the stack any further
3001 // because the guard pages are in the way, and a segfault occurs.
3002 //
3003 // However, it's essential not to split the stack region by unmapping
3004 // a region (leaving a hole) that's already part of the stack mapping,
3005 // so if the stack mapping has already grown beyond the guard pages at
3006 // the time we create them, we have to truncate the stack mapping.
3007 // So, we need to know the extent of the stack mapping when
3008 // create_stack_guard_pages() is called.
3009
3010 // We only need this for stacks that are growable: at the time of
3011 // writing thread stacks don't use growable mappings (i.e. those
3012 // creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this
3013 // only applies to the main thread.
3014
3015 // If the (growable) stack mapping already extends beyond the point
3016 // where we're going to put our guard pages, truncate the mapping at
3017 // that point by munmap()ping it. This ensures that when we later
3018 // munmap() the guard pages we don't leave a hole in the stack
3019 // mapping. This only affects the main/initial thread
3020
3021 bool os::pd_create_stack_guard_pages(char* addr, size_t size) {
3022
3023 if (os::Linux::is_initial_thread()) {
3024 // As we manually grow stack up to bottom inside create_attached_thread(),
3025 // it's likely that os::Linux::initial_thread_stack_bottom is mapped and
3026 // we don't need to do anything special.
3027 // Check it first, before calling heavy function.
3028 uintptr_t stack_extent = (uintptr_t) os::Linux::initial_thread_stack_bottom();
3029 unsigned char vec[1];
3030
3031 if (mincore((address)stack_extent, os::vm_page_size(), vec) == -1) {
3032 // Fallback to slow path on all errors, including EAGAIN
3033 stack_extent = (uintptr_t) get_stack_commited_bottom(
3034 os::Linux::initial_thread_stack_bottom(),
3035 (size_t)addr - stack_extent);
3036 }
3037
3038 if (stack_extent < (uintptr_t)addr) {
3039 ::munmap((void*)stack_extent, (uintptr_t)(addr - stack_extent));
3040 }
3041 }
3042
3043 return os::commit_memory(addr, size, !ExecMem);
3044 }
3045
3046 // If this is a growable mapping, remove the guard pages entirely by
3047 // munmap()ping them. If not, just call uncommit_memory(). This only
3048 // affects the main/initial thread, but guard against future OS changes
3049 // It's safe to always unmap guard pages for initial thread because we
3050 // always place it right after end of the mapped region
3051
3052 bool os::remove_stack_guard_pages(char* addr, size_t size) {
3053 uintptr_t stack_extent, stack_base;
3054
3055 if (os::Linux::is_initial_thread()) {
3056 return ::munmap(addr, size) == 0;
3057 }
3058
3059 return os::uncommit_memory(addr, size);
3060 }
3061
3062 static address _highest_vm_reserved_address = NULL;
3063
3064 // If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory
3065 // at 'requested_addr'. If there are existing memory mappings at the same
3066 // location, however, they will be overwritten. If 'fixed' is false,
3067 // 'requested_addr' is only treated as a hint, the return value may or
3068 // may not start from the requested address. Unlike Linux mmap(), this
3069 // function returns NULL to indicate failure.
3070 static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) {
3071 char * addr;
3072 int flags;
3073
3074 flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS;
3075 if (fixed) {
3076 assert((uintptr_t)requested_addr % os::Linux::page_size() == 0, "unaligned address");
3077 flags |= MAP_FIXED;
3078 }
3079
3080 // Map reserved/uncommitted pages PROT_NONE so we fail early if we
3081 // touch an uncommitted page. Otherwise, the read/write might
3082 // succeed if we have enough swap space to back the physical page.
3083 addr = (char*)::mmap(requested_addr, bytes, PROT_NONE,
3084 flags, -1, 0);
3085
3086 if (addr != MAP_FAILED) {
3087 // anon_mmap() should only get called during VM initialization,
3088 // don't need lock (actually we can skip locking even it can be called
3089 // from multiple threads, because _highest_vm_reserved_address is just a
3090 // hint about the upper limit of non-stack memory regions.)
3091 if ((address)addr + bytes > _highest_vm_reserved_address) {
3092 _highest_vm_reserved_address = (address)addr + bytes;
3093 }
3094 }
3095
3096 return addr == MAP_FAILED ? NULL : addr;
3097 }
3098
3099 // Don't update _highest_vm_reserved_address, because there might be memory
3100 // regions above addr + size. If so, releasing a memory region only creates
3101 // a hole in the address space, it doesn't help prevent heap-stack collision.
3102 //
3103 static int anon_munmap(char * addr, size_t size) {
3104 return ::munmap(addr, size) == 0;
3105 }
3106
3107 char* os::pd_reserve_memory(size_t bytes, char* requested_addr,
3108 size_t alignment_hint) {
3109 return anon_mmap(requested_addr, bytes, (requested_addr != NULL));
3110 }
3111
3112 bool os::pd_release_memory(char* addr, size_t size) {
3113 return anon_munmap(addr, size);
3114 }
3115
3116 static address highest_vm_reserved_address() {
3117 return _highest_vm_reserved_address;
3118 }
3119
3120 static bool linux_mprotect(char* addr, size_t size, int prot) {
3121 // Linux wants the mprotect address argument to be page aligned.
3122 char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::page_size());
3123
3124 // According to SUSv3, mprotect() should only be used with mappings
3125 // established by mmap(), and mmap() always maps whole pages. Unaligned
3126 // 'addr' likely indicates problem in the VM (e.g. trying to change
3127 // protection of malloc'ed or statically allocated memory). Check the
3128 // caller if you hit this assert.
3129 assert(addr == bottom, "sanity check");
3130
3131 size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Linux::page_size());
3132 return ::mprotect(bottom, size, prot) == 0;
3133 }
3134
3135 // Set protections specified
3136 bool os::protect_memory(char* addr, size_t bytes, ProtType prot,
3137 bool is_committed) {
3138 unsigned int p = 0;
3139 switch (prot) {
3140 case MEM_PROT_NONE: p = PROT_NONE; break;
3141 case MEM_PROT_READ: p = PROT_READ; break;
3142 case MEM_PROT_RW: p = PROT_READ|PROT_WRITE; break;
3143 case MEM_PROT_RWX: p = PROT_READ|PROT_WRITE|PROT_EXEC; break;
3144 default:
3145 ShouldNotReachHere();
3146 }
3147 // is_committed is unused.
3148 return linux_mprotect(addr, bytes, p);
3149 }
3150
3151 bool os::guard_memory(char* addr, size_t size) {
3152 return linux_mprotect(addr, size, PROT_NONE);
3153 }
3154
3155 bool os::unguard_memory(char* addr, size_t size) {
3156 return linux_mprotect(addr, size, PROT_READ|PROT_WRITE);
3157 }
3158
3159 bool os::Linux::transparent_huge_pages_sanity_check(bool warn, size_t page_size) {
3160 bool result = false;
3161 void *p = mmap(NULL, page_size * 2, PROT_READ|PROT_WRITE,
3162 MAP_ANONYMOUS|MAP_PRIVATE,
3163 -1, 0);
3164 if (p != MAP_FAILED) {
3165 void *aligned_p = align_ptr_up(p, page_size);
3166
3167 result = madvise(aligned_p, page_size, MADV_HUGEPAGE) == 0;
3168
3169 munmap(p, page_size * 2);
3170 }
3171
3172 if (warn && !result) {
3173 warning("TransparentHugePages is not supported by the operating system.");
3174 }
3175
3176 return result;
3177 }
3178
3179 bool os::Linux::hugetlbfs_sanity_check(bool warn, size_t page_size) {
3180 bool result = false;
3181 void *p = mmap(NULL, page_size, PROT_READ|PROT_WRITE,
3182 MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB,
3183 -1, 0);
3184
3185 if (p != MAP_FAILED) {
3186 // We don't know if this really is a huge page or not.
3187 FILE *fp = fopen("/proc/self/maps", "r");
3188 if (fp) {
3189 while (!feof(fp)) {
3190 char chars[257];
3191 long x = 0;
3192 if (fgets(chars, sizeof(chars), fp)) {
3193 if (sscanf(chars, "%lx-%*x", &x) == 1
3194 && x == (long)p) {
3195 if (strstr (chars, "hugepage")) {
3196 result = true;
3197 break;
3198 }
3199 }
3200 }
3201 }
3202 fclose(fp);
3203 }
3204 munmap(p, page_size);
3205 }
3206
3207 if (warn && !result) {
3208 warning("HugeTLBFS is not supported by the operating system.");
3209 }
3210
3211 return result;
3212 }
3213
3214 /*
3215 * Set the coredump_filter bits to include largepages in core dump (bit 6)
3216 *
3217 * From the coredump_filter documentation:
3218 *
3219 * - (bit 0) anonymous private memory
3220 * - (bit 1) anonymous shared memory
3221 * - (bit 2) file-backed private memory
3222 * - (bit 3) file-backed shared memory
3223 * - (bit 4) ELF header pages in file-backed private memory areas (it is
3224 * effective only if the bit 2 is cleared)
3225 * - (bit 5) hugetlb private memory
3226 * - (bit 6) hugetlb shared memory
3227 */
3228 static void set_coredump_filter(void) {
3229 FILE *f;
3230 long cdm;
3231
3232 if ((f = fopen("/proc/self/coredump_filter", "r+")) == NULL) {
3233 return;
3234 }
3235
3236 if (fscanf(f, "%lx", &cdm) != 1) {
3237 fclose(f);
3238 return;
3239 }
3240
3241 rewind(f);
3242
3243 if ((cdm & LARGEPAGES_BIT) == 0) {
3244 cdm |= LARGEPAGES_BIT;
3245 fprintf(f, "%#lx", cdm);
3246 }
3247
3248 fclose(f);
3249 }
3250
3251 // Large page support
3252
3253 static size_t _large_page_size = 0;
3254
3255 size_t os::Linux::find_large_page_size() {
3256 size_t large_page_size = 0;
3257
3258 // large_page_size on Linux is used to round up heap size. x86 uses either
3259 // 2M or 4M page, depending on whether PAE (Physical Address Extensions)
3260 // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use
3261 // page as large as 256M.
3262 //
3263 // Here we try to figure out page size by parsing /proc/meminfo and looking
3264 // for a line with the following format:
3265 // Hugepagesize: 2048 kB
3266 //
3267 // If we can't determine the value (e.g. /proc is not mounted, or the text
3268 // format has been changed), we'll use the largest page size supported by
3269 // the processor.
3270
3271 #ifndef ZERO
3272 large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M)
3273 ARM_ONLY(2 * M) PPC_ONLY(4 * M);
3274 #endif // ZERO
3275
3276 FILE *fp = fopen("/proc/meminfo", "r");
3277 if (fp) {
3278 while (!feof(fp)) {
3279 int x = 0;
3280 char buf[16];
3281 if (fscanf(fp, "Hugepagesize: %d", &x) == 1) {
3282 if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) {
3283 large_page_size = x * K;
3284 break;
3285 }
3286 } else {
3287 // skip to next line
3288 for (;;) {
3289 int ch = fgetc(fp);
3290 if (ch == EOF || ch == (int)'\n') break;
3291 }
3292 }
3293 }
3294 fclose(fp);
3295 }
3296
3297 if (!FLAG_IS_DEFAULT(LargePageSizeInBytes) && LargePageSizeInBytes != large_page_size) {
3298 warning("Setting LargePageSizeInBytes has no effect on this OS. Large page size is "
3299 SIZE_FORMAT "%s.", byte_size_in_proper_unit(large_page_size),
3300 proper_unit_for_byte_size(large_page_size));
3301 }
3302
3303 return large_page_size;
3304 }
3305
3306 size_t os::Linux::setup_large_page_size() {
3307 _large_page_size = Linux::find_large_page_size();
3308 const size_t default_page_size = (size_t)Linux::page_size();
3309 if (_large_page_size > default_page_size) {
3310 _page_sizes[0] = _large_page_size;
3311 _page_sizes[1] = default_page_size;
3312 _page_sizes[2] = 0;
3313 }
3314
3315 return _large_page_size;
3316 }
3317
3318 bool os::Linux::setup_large_page_type(size_t page_size) {
3319 if (FLAG_IS_DEFAULT(UseHugeTLBFS) &&
3320 FLAG_IS_DEFAULT(UseSHM) &&
3321 FLAG_IS_DEFAULT(UseTransparentHugePages)) {
3322
3323 // The type of large pages has not been specified by the user.
3324
3325 // Try UseHugeTLBFS and then UseSHM.
3326 UseHugeTLBFS = UseSHM = true;
3327
3328 // Don't try UseTransparentHugePages since there are known
3329 // performance issues with it turned on. This might change in the future.
3330 UseTransparentHugePages = false;
3331 }
3332
3333 if (UseTransparentHugePages) {
3334 bool warn_on_failure = !FLAG_IS_DEFAULT(UseTransparentHugePages);
3335 if (transparent_huge_pages_sanity_check(warn_on_failure, page_size)) {
3336 UseHugeTLBFS = false;
3337 UseSHM = false;
3338 return true;
3339 }
3340 UseTransparentHugePages = false;
3341 }
3342
3343 if (UseHugeTLBFS) {
3344 bool warn_on_failure = !FLAG_IS_DEFAULT(UseHugeTLBFS);
3345 if (hugetlbfs_sanity_check(warn_on_failure, page_size)) {
3346 UseSHM = false;
3347 return true;
3348 }
3349 UseHugeTLBFS = false;
3350 }
3351
3352 return UseSHM;
3353 }
3354
3355 void os::large_page_init() {
3356 if (!UseLargePages &&
3357 !UseTransparentHugePages &&
3358 !UseHugeTLBFS &&
3359 !UseSHM) {
3360 // Not using large pages.
3361 return;
3362 }
3363
3364 if (!FLAG_IS_DEFAULT(UseLargePages) && !UseLargePages) {
3365 // The user explicitly turned off large pages.
3366 // Ignore the rest of the large pages flags.
3367 UseTransparentHugePages = false;
3368 UseHugeTLBFS = false;
3369 UseSHM = false;
3370 return;
3371 }
3372
3373 size_t large_page_size = Linux::setup_large_page_size();
3374 UseLargePages = Linux::setup_large_page_type(large_page_size);
3375
3376 set_coredump_filter();
3377 }
3378
3379 #ifndef SHM_HUGETLB
3380 #define SHM_HUGETLB 04000
3381 #endif
3382
3383 char* os::Linux::reserve_memory_special_shm(size_t bytes, size_t alignment, char* req_addr, bool exec) {
3384 // "exec" is passed in but not used. Creating the shared image for
3385 // the code cache doesn't have an SHM_X executable permission to check.
3386 assert(UseLargePages && UseSHM, "only for SHM large pages");
3387 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address");
3388
3389 if (!is_size_aligned(bytes, os::large_page_size()) || alignment > os::large_page_size()) {
3390 return NULL; // Fallback to small pages.
3391 }
3392
3393 key_t key = IPC_PRIVATE;
3394 char *addr;
3395
3396 bool warn_on_failure = UseLargePages &&
3397 (!FLAG_IS_DEFAULT(UseLargePages) ||
3398 !FLAG_IS_DEFAULT(UseSHM) ||
3399 !FLAG_IS_DEFAULT(LargePageSizeInBytes)
3400 );
3401 char msg[128];
3402
3403 // Create a large shared memory region to attach to based on size.
3404 // Currently, size is the total size of the heap
3405 int shmid = shmget(key, bytes, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W);
3406 if (shmid == -1) {
3407 // Possible reasons for shmget failure:
3408 // 1. shmmax is too small for Java heap.
3409 // > check shmmax value: cat /proc/sys/kernel/shmmax
3410 // > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax
3411 // 2. not enough large page memory.
3412 // > check available large pages: cat /proc/meminfo
3413 // > increase amount of large pages:
3414 // echo new_value > /proc/sys/vm/nr_hugepages
3415 // Note 1: different Linux may use different name for this property,
3416 // e.g. on Redhat AS-3 it is "hugetlb_pool".
3417 // Note 2: it's possible there's enough physical memory available but
3418 // they are so fragmented after a long run that they can't
3419 // coalesce into large pages. Try to reserve large pages when
3420 // the system is still "fresh".
3421 if (warn_on_failure) {
3422 jio_snprintf(msg, sizeof(msg), "Failed to reserve shared memory (errno = %d).", errno);
3423 warning("%s", msg);
3424 }
3425 return NULL;
3426 }
3427
3428 // attach to the region
3429 addr = (char*)shmat(shmid, req_addr, 0);
3430 int err = errno;
3431
3432 // Remove shmid. If shmat() is successful, the actual shared memory segment
3433 // will be deleted when it's detached by shmdt() or when the process
3434 // terminates. If shmat() is not successful this will remove the shared
3435 // segment immediately.
3436 shmctl(shmid, IPC_RMID, NULL);
3437
3438 if ((intptr_t)addr == -1) {
3439 if (warn_on_failure) {
3440 jio_snprintf(msg, sizeof(msg), "Failed to attach shared memory (errno = %d).", err);
3441 warning("%s", msg);
3442 }
3443 return NULL;
3444 }
3445
3446 return addr;
3447 }
3448
3449 static void warn_on_large_pages_failure(char* req_addr, size_t bytes, int error) {
3450 assert(error == ENOMEM, "Only expect to fail if no memory is available");
3451
3452 bool warn_on_failure = UseLargePages &&
3453 (!FLAG_IS_DEFAULT(UseLargePages) ||
3454 !FLAG_IS_DEFAULT(UseHugeTLBFS) ||
3455 !FLAG_IS_DEFAULT(LargePageSizeInBytes));
3456
3457 if (warn_on_failure) {
3458 char msg[128];
3459 jio_snprintf(msg, sizeof(msg), "Failed to reserve large pages memory req_addr: "
3460 PTR_FORMAT " bytes: " SIZE_FORMAT " (errno = %d).", req_addr, bytes, error);
3461 warning("%s", msg);
3462 }
3463 }
3464
3465 char* os::Linux::reserve_memory_special_huge_tlbfs_only(size_t bytes, char* req_addr, bool exec) {
3466 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages");
3467 assert(is_size_aligned(bytes, os::large_page_size()), "Unaligned size");
3468 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address");
3469
3470 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
3471 char* addr = (char*)::mmap(req_addr, bytes, prot,
3472 MAP_PRIVATE|MAP_ANONYMOUS|MAP_HUGETLB,
3473 -1, 0);
3474
3475 if (addr == MAP_FAILED) {
3476 warn_on_large_pages_failure(req_addr, bytes, errno);
3477 return NULL;
3478 }
3479
3480 assert(is_ptr_aligned(addr, os::large_page_size()), "Must be");
3481
3482 return addr;
3483 }
3484
3485 char* os::Linux::reserve_memory_special_huge_tlbfs_mixed(size_t bytes, size_t alignment, char* req_addr, bool exec) {
3486 size_t large_page_size = os::large_page_size();
3487
3488 assert(bytes >= large_page_size, "Shouldn't allocate large pages for small sizes");
3489
3490 // Allocate small pages.
3491
3492 char* start;
3493 if (req_addr != NULL) {
3494 assert(is_ptr_aligned(req_addr, alignment), "Must be");
3495 assert(is_size_aligned(bytes, alignment), "Must be");
3496 start = os::reserve_memory(bytes, req_addr);
3497 assert(start == NULL || start == req_addr, "Must be");
3498 } else {
3499 start = os::reserve_memory_aligned(bytes, alignment);
3500 }
3501
3502 if (start == NULL) {
3503 return NULL;
3504 }
3505
3506 assert(is_ptr_aligned(start, alignment), "Must be");
3507
3508 if (MemTracker::tracking_level() > NMT_minimal) {
3509 // os::reserve_memory_special will record this memory area.
3510 // Need to release it here to prevent overlapping reservations.
3511 Tracker tkr = MemTracker::get_virtual_memory_release_tracker();
3512 tkr.record((address)start, bytes);
3513 }
3514
3515 char* end = start + bytes;
3516
3517 // Find the regions of the allocated chunk that can be promoted to large pages.
3518 char* lp_start = (char*)align_ptr_up(start, large_page_size);
3519 char* lp_end = (char*)align_ptr_down(end, large_page_size);
3520
3521 size_t lp_bytes = lp_end - lp_start;
3522
3523 assert(is_size_aligned(lp_bytes, large_page_size), "Must be");
3524
3525 if (lp_bytes == 0) {
3526 // The mapped region doesn't even span the start and the end of a large page.
3527 // Fall back to allocate a non-special area.
3528 ::munmap(start, end - start);
3529 return NULL;
3530 }
3531
3532 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
3533
3534
3535 void* result;
3536
3537 if (start != lp_start) {
3538 result = ::mmap(start, lp_start - start, prot,
3539 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED,
3540 -1, 0);
3541 if (result == MAP_FAILED) {
3542 ::munmap(lp_start, end - lp_start);
3543 return NULL;
3544 }
3545 }
3546
3547 result = ::mmap(lp_start, lp_bytes, prot,
3548 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED|MAP_HUGETLB,
3549 -1, 0);
3550 if (result == MAP_FAILED) {
3551 warn_on_large_pages_failure(req_addr, bytes, errno);
3552 // If the mmap above fails, the large pages region will be unmapped and we
3553 // have regions before and after with small pages. Release these regions.
3554 //
3555 // | mapped | unmapped | mapped |
3556 // ^ ^ ^ ^
3557 // start lp_start lp_end end
3558 //
3559 ::munmap(start, lp_start - start);
3560 ::munmap(lp_end, end - lp_end);
3561 return NULL;
3562 }
3563
3564 if (lp_end != end) {
3565 result = ::mmap(lp_end, end - lp_end, prot,
3566 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED,
3567 -1, 0);
3568 if (result == MAP_FAILED) {
3569 ::munmap(start, lp_end - start);
3570 return NULL;
3571 }
3572 }
3573
3574 return start;
3575 }
3576
3577 char* os::Linux::reserve_memory_special_huge_tlbfs(size_t bytes, size_t alignment, char* req_addr, bool exec) {
3578 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages");
3579 assert(is_ptr_aligned(req_addr, alignment), "Must be");
3580 assert(is_power_of_2(alignment), "Must be");
3581 assert(is_power_of_2(os::large_page_size()), "Must be");
3582 assert(bytes >= os::large_page_size(), "Shouldn't allocate large pages for small sizes");
3583
3584 if (is_size_aligned(bytes, os::large_page_size()) && alignment <= os::large_page_size()) {
3585 return reserve_memory_special_huge_tlbfs_only(bytes, req_addr, exec);
3586 } else {
3587 return reserve_memory_special_huge_tlbfs_mixed(bytes, alignment, req_addr, exec);
3588 }
3589 }
3590
3591 char* os::reserve_memory_special(size_t bytes, size_t alignment, char* req_addr, bool exec) {
3592 assert(UseLargePages, "only for large pages");
3593
3594 char* addr;
3595 if (UseSHM) {
3596 addr = os::Linux::reserve_memory_special_shm(bytes, alignment, req_addr, exec);
3597 } else {
3598 assert(UseHugeTLBFS, "must be");
3599 addr = os::Linux::reserve_memory_special_huge_tlbfs(bytes, alignment, req_addr, exec);
3600 }
3601
3602 if (addr != NULL) {
3603 if (UseNUMAInterleaving) {
3604 numa_make_global(addr, bytes);
3605 }
3606
3607 // The memory is committed
3608 MemTracker::record_virtual_memory_reserve_and_commit((address)addr, bytes, CALLER_PC);
3609 }
3610
3611 return addr;
3612 }
3613
3614 bool os::Linux::release_memory_special_shm(char* base, size_t bytes) {
3615 // detaching the SHM segment will also delete it, see reserve_memory_special_shm()
3616 return shmdt(base) == 0;
3617 }
3618
3619 bool os::Linux::release_memory_special_huge_tlbfs(char* base, size_t bytes) {
3620 return pd_release_memory(base, bytes);
3621 }
3622
3623 bool os::release_memory_special(char* base, size_t bytes) {
3624 bool res;
3625 if (MemTracker::tracking_level() > NMT_minimal) {
3626 Tracker tkr = MemTracker::get_virtual_memory_release_tracker();
3627 res = os::Linux::release_memory_special_impl(base, bytes);
3628 if (res) {
3629 tkr.record((address)base, bytes);
3630 }
3631
3632 } else {
3633 res = os::Linux::release_memory_special_impl(base, bytes);
3634 }
3635 return res;
3636 }
3637
3638 bool os::Linux::release_memory_special_impl(char* base, size_t bytes) {
3639 assert(UseLargePages, "only for large pages");
3640 bool res;
3641
3642 if (UseSHM) {
3643 res = os::Linux::release_memory_special_shm(base, bytes);
3644 } else {
3645 assert(UseHugeTLBFS, "must be");
3646 res = os::Linux::release_memory_special_huge_tlbfs(base, bytes);
3647 }
3648 return res;
3649 }
3650
3651 size_t os::large_page_size() {
3652 return _large_page_size;
3653 }
3654
3655 // With SysV SHM the entire memory region must be allocated as shared
3656 // memory.
3657 // HugeTLBFS allows application to commit large page memory on demand.
3658 // However, when committing memory with HugeTLBFS fails, the region
3659 // that was supposed to be committed will lose the old reservation
3660 // and allow other threads to steal that memory region. Because of this
3661 // behavior we can't commit HugeTLBFS memory.
3662 bool os::can_commit_large_page_memory() {
3663 return UseTransparentHugePages;
3664 }
3665
3666 bool os::can_execute_large_page_memory() {
3667 return UseTransparentHugePages || UseHugeTLBFS;
3668 }
3669
3670 // Reserve memory at an arbitrary address, only if that area is
3671 // available (and not reserved for something else).
3672
3673 char* os::pd_attempt_reserve_memory_at(size_t bytes, char* requested_addr) {
3674 const int max_tries = 10;
3675 char* base[max_tries];
3676 size_t size[max_tries];
3677 const size_t gap = 0x000000;
3678
3679 // Assert only that the size is a multiple of the page size, since
3680 // that's all that mmap requires, and since that's all we really know
3681 // about at this low abstraction level. If we need higher alignment,
3682 // we can either pass an alignment to this method or verify alignment
3683 // in one of the methods further up the call chain. See bug 5044738.
3684 assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block");
3685
3686 // Repeatedly allocate blocks until the block is allocated at the
3687 // right spot. Give up after max_tries. Note that reserve_memory() will
3688 // automatically update _highest_vm_reserved_address if the call is
3689 // successful. The variable tracks the highest memory address every reserved
3690 // by JVM. It is used to detect heap-stack collision if running with
3691 // fixed-stack LinuxThreads. Because here we may attempt to reserve more
3692 // space than needed, it could confuse the collision detecting code. To
3693 // solve the problem, save current _highest_vm_reserved_address and
3694 // calculate the correct value before return.
3695 address old_highest = _highest_vm_reserved_address;
3696
3697 // Linux mmap allows caller to pass an address as hint; give it a try first,
3698 // if kernel honors the hint then we can return immediately.
3699 char * addr = anon_mmap(requested_addr, bytes, false);
3700 if (addr == requested_addr) {
3701 return requested_addr;
3702 }
3703
3704 if (addr != NULL) {
3705 // mmap() is successful but it fails to reserve at the requested address
3706 anon_munmap(addr, bytes);
3707 }
3708
3709 int i;
3710 for (i = 0; i < max_tries; ++i) {
3711 base[i] = reserve_memory(bytes);
3712
3713 if (base[i] != NULL) {
3714 // Is this the block we wanted?
3715 if (base[i] == requested_addr) {
3716 size[i] = bytes;
3717 break;
3718 }
3719
3720 // Does this overlap the block we wanted? Give back the overlapped
3721 // parts and try again.
3722
3723 size_t top_overlap = requested_addr + (bytes + gap) - base[i];
3724 if (top_overlap >= 0 && top_overlap < bytes) {
3725 unmap_memory(base[i], top_overlap);
3726 base[i] += top_overlap;
3727 size[i] = bytes - top_overlap;
3728 } else {
3729 size_t bottom_overlap = base[i] + bytes - requested_addr;
3730 if (bottom_overlap >= 0 && bottom_overlap < bytes) {
3731 unmap_memory(requested_addr, bottom_overlap);
3732 size[i] = bytes - bottom_overlap;
3733 } else {
3734 size[i] = bytes;
3735 }
3736 }
3737 }
3738 }
3739
3740 // Give back the unused reserved pieces.
3741
3742 for (int j = 0; j < i; ++j) {
3743 if (base[j] != NULL) {
3744 unmap_memory(base[j], size[j]);
3745 }
3746 }
3747
3748 if (i < max_tries) {
3749 _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes);
3750 return requested_addr;
3751 } else {
3752 _highest_vm_reserved_address = old_highest;
3753 return NULL;
3754 }
3755 }
3756
3757 size_t os::read(int fd, void *buf, unsigned int nBytes) {
3758 return ::read(fd, buf, nBytes);
3759 }
3760
3761 //
3762 // Short sleep, direct OS call.
3763 //
3764 // Note: certain versions of Linux CFS scheduler (since 2.6.23) do not guarantee
3765 // sched_yield(2) will actually give up the CPU:
3766 //
3767 // * Alone on this pariticular CPU, keeps running.
3768 // * Before the introduction of "skip_buddy" with "compat_yield" disabled
3769 // (pre 2.6.39).
3770 //
3771 // So calling this with 0 is an alternative.
3772 //
3773 void os::naked_short_sleep(jlong ms) {
3774 struct timespec req;
3775
3776 assert(ms < 1000, "Un-interruptable sleep, short time use only");
3777 req.tv_sec = 0;
3778 if (ms > 0) {
3779 req.tv_nsec = (ms % 1000) * 1000000;
3780 }
3781 else {
3782 req.tv_nsec = 1;
3783 }
3784
3785 nanosleep(&req, NULL);
3786
3787 return;
3788 }
3789
3790 // Sleep forever; naked call to OS-specific sleep; use with CAUTION
3791 void os::infinite_sleep() {
3792 while (true) { // sleep forever ...
3793 ::sleep(100); // ... 100 seconds at a time
3794 }
3795 }
3796
3797 // Used to convert frequent JVM_Yield() to nops
3798 bool os::dont_yield() {
3799 return DontYieldALot;
3800 }
3801
3802 void os::naked_yield() {
3803 sched_yield();
3804 }
3805
3806 ////////////////////////////////////////////////////////////////////////////////
3807 // thread priority support
3808
3809 // Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER
3810 // only supports dynamic priority, static priority must be zero. For real-time
3811 // applications, Linux supports SCHED_RR which allows static priority (1-99).
3812 // However, for large multi-threaded applications, SCHED_RR is not only slower
3813 // than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out
3814 // of 5 runs - Sep 2005).
3815 //
3816 // The following code actually changes the niceness of kernel-thread/LWP. It
3817 // has an assumption that setpriority() only modifies one kernel-thread/LWP,
3818 // not the entire user process, and user level threads are 1:1 mapped to kernel
3819 // threads. It has always been the case, but could change in the future. For
3820 // this reason, the code should not be used as default (ThreadPriorityPolicy=0).
3821 // It is only used when ThreadPriorityPolicy=1 and requires root privilege.
3822
3823 int os::java_to_os_priority[CriticalPriority + 1] = {
3824 19, // 0 Entry should never be used
3825
3826 4, // 1 MinPriority
3827 3, // 2
3828 2, // 3
3829
3830 1, // 4
3831 0, // 5 NormPriority
3832 -1, // 6
3833
3834 -2, // 7
3835 -3, // 8
3836 -4, // 9 NearMaxPriority
3837
3838 -5, // 10 MaxPriority
3839
3840 -5 // 11 CriticalPriority
3841 };
3842
3843 static int prio_init() {
3844 if (ThreadPriorityPolicy == 1) {
3845 // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1
3846 // if effective uid is not root. Perhaps, a more elegant way of doing
3847 // this is to test CAP_SYS_NICE capability, but that will require libcap.so
3848 if (geteuid() != 0) {
3849 if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) {
3850 warning("-XX:ThreadPriorityPolicy requires root privilege on Linux");
3851 }
3852 ThreadPriorityPolicy = 0;
3853 }
3854 }
3855 if (UseCriticalJavaThreadPriority) {
3856 os::java_to_os_priority[MaxPriority] = os::java_to_os_priority[CriticalPriority];
3857 }
3858 return 0;
3859 }
3860
3861 OSReturn os::set_native_priority(Thread* thread, int newpri) {
3862 if (!UseThreadPriorities || ThreadPriorityPolicy == 0) return OS_OK;
3863
3864 int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri);
3865 return (ret == 0) ? OS_OK : OS_ERR;
3866 }
3867
3868 OSReturn os::get_native_priority(const Thread* const thread, int *priority_ptr) {
3869 if (!UseThreadPriorities || ThreadPriorityPolicy == 0) {
3870 *priority_ptr = java_to_os_priority[NormPriority];
3871 return OS_OK;
3872 }
3873
3874 errno = 0;
3875 *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id());
3876 return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR);
3877 }
3878
3879 // Hint to the underlying OS that a task switch would not be good.
3880 // Void return because it's a hint and can fail.
3881 void os::hint_no_preempt() {}
3882
3883 ////////////////////////////////////////////////////////////////////////////////
3884 // suspend/resume support
3885
3886 // the low-level signal-based suspend/resume support is a remnant from the
3887 // old VM-suspension that used to be for java-suspension, safepoints etc,
3888 // within hotspot. Now there is a single use-case for this:
3889 // - calling get_thread_pc() on the VMThread by the flat-profiler task
3890 // that runs in the watcher thread.
3891 // The remaining code is greatly simplified from the more general suspension
3892 // code that used to be used.
3893 //
3894 // The protocol is quite simple:
3895 // - suspend:
3896 // - sends a signal to the target thread
3897 // - polls the suspend state of the osthread using a yield loop
3898 // - target thread signal handler (SR_handler) sets suspend state
3899 // and blocks in sigsuspend until continued
3900 // - resume:
3901 // - sets target osthread state to continue
3902 // - sends signal to end the sigsuspend loop in the SR_handler
3903 //
3904 // Note that the SR_lock plays no role in this suspend/resume protocol.
3905 //
3906
3907 static void resume_clear_context(OSThread *osthread) {
3908 osthread->set_ucontext(NULL);
3909 osthread->set_siginfo(NULL);
3910 }
3911
3912 static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo, ucontext_t* context) {
3913 osthread->set_ucontext(context);
3914 osthread->set_siginfo(siginfo);
3915 }
3916
3917 //
3918 // Handler function invoked when a thread's execution is suspended or
3919 // resumed. We have to be careful that only async-safe functions are
3920 // called here (Note: most pthread functions are not async safe and
3921 // should be avoided.)
3922 //
3923 // Note: sigwait() is a more natural fit than sigsuspend() from an
3924 // interface point of view, but sigwait() prevents the signal hander
3925 // from being run. libpthread would get very confused by not having
3926 // its signal handlers run and prevents sigwait()'s use with the
3927 // mutex granting granting signal.
3928 //
3929 // Currently only ever called on the VMThread and JavaThreads (PC sampling)
3930 //
3931 static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) {
3932 // Save and restore errno to avoid confusing native code with EINTR
3933 // after sigsuspend.
3934 int old_errno = errno;
3935
3936 Thread* thread = Thread::current();
3937 OSThread* osthread = thread->osthread();
3938 assert(thread->is_VM_thread() || thread->is_Java_thread(), "Must be VMThread or JavaThread");
3939
3940 os::SuspendResume::State current = osthread->sr.state();
3941 if (current == os::SuspendResume::SR_SUSPEND_REQUEST) {
3942 suspend_save_context(osthread, siginfo, context);
3943
3944 // attempt to switch the state, we assume we had a SUSPEND_REQUEST
3945 os::SuspendResume::State state = osthread->sr.suspended();
3946 if (state == os::SuspendResume::SR_SUSPENDED) {
3947 sigset_t suspend_set; // signals for sigsuspend()
3948
3949 // get current set of blocked signals and unblock resume signal
3950 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set);
3951 sigdelset(&suspend_set, SR_signum);
3952
3953 sr_semaphore.signal();
3954 // wait here until we are resumed
3955 while (1) {
3956 sigsuspend(&suspend_set);
3957
3958 os::SuspendResume::State result = osthread->sr.running();
3959 if (result == os::SuspendResume::SR_RUNNING) {
3960 sr_semaphore.signal();
3961 break;
3962 }
3963 }
3964
3965 } else if (state == os::SuspendResume::SR_RUNNING) {
3966 // request was cancelled, continue
3967 } else {
3968 ShouldNotReachHere();
3969 }
3970
3971 resume_clear_context(osthread);
3972 } else if (current == os::SuspendResume::SR_RUNNING) {
3973 // request was cancelled, continue
3974 } else if (current == os::SuspendResume::SR_WAKEUP_REQUEST) {
3975 // ignore
3976 } else {
3977 // ignore
3978 }
3979
3980 errno = old_errno;
3981 }
3982
3983
3984 static int SR_initialize() {
3985 struct sigaction act;
3986 char *s;
3987 /* Get signal number to use for suspend/resume */
3988 if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) {
3989 int sig = ::strtol(s, 0, 10);
3990 if (sig > 0 || sig < _NSIG) {
3991 SR_signum = sig;
3992 }
3993 }
3994
3995 assert(SR_signum > SIGSEGV && SR_signum > SIGBUS,
3996 "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769");
3997
3998 sigemptyset(&SR_sigset);
3999 sigaddset(&SR_sigset, SR_signum);
4000
4001 /* Set up signal handler for suspend/resume */
4002 act.sa_flags = SA_RESTART|SA_SIGINFO;
4003 act.sa_handler = (void (*)(int)) SR_handler;
4004
4005 // SR_signum is blocked by default.
4006 // 4528190 - We also need to block pthread restart signal (32 on all
4007 // supported Linux platforms). Note that LinuxThreads need to block
4008 // this signal for all threads to work properly. So we don't have
4009 // to use hard-coded signal number when setting up the mask.
4010 pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask);
4011
4012 if (sigaction(SR_signum, &act, 0) == -1) {
4013 return -1;
4014 }
4015
4016 // Save signal flag
4017 os::Linux::set_our_sigflags(SR_signum, act.sa_flags);
4018 return 0;
4019 }
4020
4021 static int sr_notify(OSThread* osthread) {
4022 int status = pthread_kill(osthread->pthread_id(), SR_signum);
4023 assert_status(status == 0, status, "pthread_kill");
4024 return status;
4025 }
4026
4027 // "Randomly" selected value for how long we want to spin
4028 // before bailing out on suspending a thread, also how often
4029 // we send a signal to a thread we want to resume
4030 static const int RANDOMLY_LARGE_INTEGER = 1000000;
4031 static const int RANDOMLY_LARGE_INTEGER2 = 100;
4032
4033 // returns true on success and false on error - really an error is fatal
4034 // but this seems the normal response to library errors
4035 static bool do_suspend(OSThread* osthread) {
4036 assert(osthread->sr.is_running(), "thread should be running");
4037 assert(!sr_semaphore.trywait(), "semaphore has invalid state");
4038
4039 // mark as suspended and send signal
4040 if (osthread->sr.request_suspend() != os::SuspendResume::SR_SUSPEND_REQUEST) {
4041 // failed to switch, state wasn't running?
4042 ShouldNotReachHere();
4043 return false;
4044 }
4045
4046 if (sr_notify(osthread) != 0) {
4047 ShouldNotReachHere();
4048 }
4049
4050 // managed to send the signal and switch to SUSPEND_REQUEST, now wait for SUSPENDED
4051 while (true) {
4052 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) {
4053 break;
4054 } else {
4055 // timeout
4056 os::SuspendResume::State cancelled = osthread->sr.cancel_suspend();
4057 if (cancelled == os::SuspendResume::SR_RUNNING) {
4058 return false;
4059 } else if (cancelled == os::SuspendResume::SR_SUSPENDED) {
4060 // make sure that we consume the signal on the semaphore as well
4061 sr_semaphore.wait();
4062 break;
4063 } else {
4064 ShouldNotReachHere();
4065 return false;
4066 }
4067 }
4068 }
4069
4070 guarantee(osthread->sr.is_suspended(), "Must be suspended");
4071 return true;
4072 }
4073
4074 static void do_resume(OSThread* osthread) {
4075 assert(osthread->sr.is_suspended(), "thread should be suspended");
4076 assert(!sr_semaphore.trywait(), "invalid semaphore state");
4077
4078 if (osthread->sr.request_wakeup() != os::SuspendResume::SR_WAKEUP_REQUEST) {
4079 // failed to switch to WAKEUP_REQUEST
4080 ShouldNotReachHere();
4081 return;
4082 }
4083
4084 while (true) {
4085 if (sr_notify(osthread) == 0) {
4086 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) {
4087 if (osthread->sr.is_running()) {
4088 return;
4089 }
4090 }
4091 } else {
4092 ShouldNotReachHere();
4093 }
4094 }
4095
4096 guarantee(osthread->sr.is_running(), "Must be running!");
4097 }
4098
4099 ///////////////////////////////////////////////////////////////////////////////////
4100 // signal handling (except suspend/resume)
4101
4102 // This routine may be used by user applications as a "hook" to catch signals.
4103 // The user-defined signal handler must pass unrecognized signals to this
4104 // routine, and if it returns true (non-zero), then the signal handler must
4105 // return immediately. If the flag "abort_if_unrecognized" is true, then this
4106 // routine will never retun false (zero), but instead will execute a VM panic
4107 // routine kill the process.
4108 //
4109 // If this routine returns false, it is OK to call it again. This allows
4110 // the user-defined signal handler to perform checks either before or after
4111 // the VM performs its own checks. Naturally, the user code would be making
4112 // a serious error if it tried to handle an exception (such as a null check
4113 // or breakpoint) that the VM was generating for its own correct operation.
4114 //
4115 // This routine may recognize any of the following kinds of signals:
4116 // SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1.
4117 // It should be consulted by handlers for any of those signals.
4118 //
4119 // The caller of this routine must pass in the three arguments supplied
4120 // to the function referred to in the "sa_sigaction" (not the "sa_handler")
4121 // field of the structure passed to sigaction(). This routine assumes that
4122 // the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART.
4123 //
4124 // Note that the VM will print warnings if it detects conflicting signal
4125 // handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers".
4126 //
4127 extern "C" JNIEXPORT int
4128 JVM_handle_linux_signal(int signo, siginfo_t* siginfo,
4129 void* ucontext, int abort_if_unrecognized);
4130
4131 void signalHandler(int sig, siginfo_t* info, void* uc) {
4132 assert(info != NULL && uc != NULL, "it must be old kernel");
4133 int orig_errno = errno; // Preserve errno value over signal handler.
4134 JVM_handle_linux_signal(sig, info, uc, true);
4135 errno = orig_errno;
4136 }
4137
4138
4139 // This boolean allows users to forward their own non-matching signals
4140 // to JVM_handle_linux_signal, harmlessly.
4141 bool os::Linux::signal_handlers_are_installed = false;
4142
4143 // For signal-chaining
4144 struct sigaction os::Linux::sigact[MAXSIGNUM];
4145 unsigned int os::Linux::sigs = 0;
4146 bool os::Linux::libjsig_is_loaded = false;
4147 typedef struct sigaction *(*get_signal_t)(int);
4148 get_signal_t os::Linux::get_signal_action = NULL;
4149
4150 struct sigaction* os::Linux::get_chained_signal_action(int sig) {
4151 struct sigaction *actp = NULL;
4152
4153 if (libjsig_is_loaded) {
4154 // Retrieve the old signal handler from libjsig
4155 actp = (*get_signal_action)(sig);
4156 }
4157 if (actp == NULL) {
4158 // Retrieve the preinstalled signal handler from jvm
4159 actp = get_preinstalled_handler(sig);
4160 }
4161
4162 return actp;
4163 }
4164
4165 static bool call_chained_handler(struct sigaction *actp, int sig,
4166 siginfo_t *siginfo, void *context) {
4167 // Call the old signal handler
4168 if (actp->sa_handler == SIG_DFL) {
4169 // It's more reasonable to let jvm treat it as an unexpected exception
4170 // instead of taking the default action.
4171 return false;
4172 } else if (actp->sa_handler != SIG_IGN) {
4173 if ((actp->sa_flags & SA_NODEFER) == 0) {
4174 // automaticlly block the signal
4175 sigaddset(&(actp->sa_mask), sig);
4176 }
4177
4178 sa_handler_t hand;
4179 sa_sigaction_t sa;
4180 bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0;
4181 // retrieve the chained handler
4182 if (siginfo_flag_set) {
4183 sa = actp->sa_sigaction;
4184 } else {
4185 hand = actp->sa_handler;
4186 }
4187
4188 if ((actp->sa_flags & SA_RESETHAND) != 0) {
4189 actp->sa_handler = SIG_DFL;
4190 }
4191
4192 // try to honor the signal mask
4193 sigset_t oset;
4194 pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset);
4195
4196 // call into the chained handler
4197 if (siginfo_flag_set) {
4198 (*sa)(sig, siginfo, context);
4199 } else {
4200 (*hand)(sig);
4201 }
4202
4203 // restore the signal mask
4204 pthread_sigmask(SIG_SETMASK, &oset, 0);
4205 }
4206 // Tell jvm's signal handler the signal is taken care of.
4207 return true;
4208 }
4209
4210 bool os::Linux::chained_handler(int sig, siginfo_t* siginfo, void* context) {
4211 bool chained = false;
4212 // signal-chaining
4213 if (UseSignalChaining) {
4214 struct sigaction *actp = get_chained_signal_action(sig);
4215 if (actp != NULL) {
4216 chained = call_chained_handler(actp, sig, siginfo, context);
4217 }
4218 }
4219 return chained;
4220 }
4221
4222 struct sigaction* os::Linux::get_preinstalled_handler(int sig) {
4223 if ((((unsigned int)1 << sig) & sigs) != 0) {
4224 return &sigact[sig];
4225 }
4226 return NULL;
4227 }
4228
4229 void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) {
4230 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4231 sigact[sig] = oldAct;
4232 sigs |= (unsigned int)1 << sig;
4233 }
4234
4235 // for diagnostic
4236 int os::Linux::sigflags[MAXSIGNUM];
4237
4238 int os::Linux::get_our_sigflags(int sig) {
4239 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4240 return sigflags[sig];
4241 }
4242
4243 void os::Linux::set_our_sigflags(int sig, int flags) {
4244 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4245 sigflags[sig] = flags;
4246 }
4247
4248 void os::Linux::set_signal_handler(int sig, bool set_installed) {
4249 // Check for overwrite.
4250 struct sigaction oldAct;
4251 sigaction(sig, (struct sigaction*)NULL, &oldAct);
4252
4253 void* oldhand = oldAct.sa_sigaction
4254 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction)
4255 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler);
4256 if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) &&
4257 oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) &&
4258 oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) {
4259 if (AllowUserSignalHandlers || !set_installed) {
4260 // Do not overwrite; user takes responsibility to forward to us.
4261 return;
4262 } else if (UseSignalChaining) {
4263 // save the old handler in jvm
4264 save_preinstalled_handler(sig, oldAct);
4265 // libjsig also interposes the sigaction() call below and saves the
4266 // old sigaction on it own.
4267 } else {
4268 fatal(err_msg("Encountered unexpected pre-existing sigaction handler "
4269 "%#lx for signal %d.", (long)oldhand, sig));
4270 }
4271 }
4272
4273 struct sigaction sigAct;
4274 sigfillset(&(sigAct.sa_mask));
4275 sigAct.sa_handler = SIG_DFL;
4276 if (!set_installed) {
4277 sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
4278 } else {
4279 sigAct.sa_sigaction = signalHandler;
4280 sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
4281 }
4282 // Save flags, which are set by ours
4283 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4284 sigflags[sig] = sigAct.sa_flags;
4285
4286 int ret = sigaction(sig, &sigAct, &oldAct);
4287 assert(ret == 0, "check");
4288
4289 void* oldhand2 = oldAct.sa_sigaction
4290 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction)
4291 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler);
4292 assert(oldhand2 == oldhand, "no concurrent signal handler installation");
4293 }
4294
4295 // install signal handlers for signals that HotSpot needs to
4296 // handle in order to support Java-level exception handling.
4297
4298 void os::Linux::install_signal_handlers() {
4299 if (!signal_handlers_are_installed) {
4300 signal_handlers_are_installed = true;
4301
4302 // signal-chaining
4303 typedef void (*signal_setting_t)();
4304 signal_setting_t begin_signal_setting = NULL;
4305 signal_setting_t end_signal_setting = NULL;
4306 begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
4307 dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting"));
4308 if (begin_signal_setting != NULL) {
4309 end_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
4310 dlsym(RTLD_DEFAULT, "JVM_end_signal_setting"));
4311 get_signal_action = CAST_TO_FN_PTR(get_signal_t,
4312 dlsym(RTLD_DEFAULT, "JVM_get_signal_action"));
4313 libjsig_is_loaded = true;
4314 assert(UseSignalChaining, "should enable signal-chaining");
4315 }
4316 if (libjsig_is_loaded) {
4317 // Tell libjsig jvm is setting signal handlers
4318 (*begin_signal_setting)();
4319 }
4320
4321 set_signal_handler(SIGSEGV, true);
4322 set_signal_handler(SIGPIPE, true);
4323 set_signal_handler(SIGBUS, true);
4324 set_signal_handler(SIGILL, true);
4325 set_signal_handler(SIGFPE, true);
4326 #if defined(PPC64)
4327 set_signal_handler(SIGTRAP, true);
4328 #endif
4329 set_signal_handler(SIGXFSZ, true);
4330
4331 if (libjsig_is_loaded) {
4332 // Tell libjsig jvm finishes setting signal handlers
4333 (*end_signal_setting)();
4334 }
4335
4336 // We don't activate signal checker if libjsig is in place, we trust ourselves
4337 // and if UserSignalHandler is installed all bets are off.
4338 // Log that signal checking is off only if -verbose:jni is specified.
4339 if (CheckJNICalls) {
4340 if (libjsig_is_loaded) {
4341 if (PrintJNIResolving) {
4342 tty->print_cr("Info: libjsig is activated, all active signal checking is disabled");
4343 }
4344 check_signals = false;
4345 }
4346 if (AllowUserSignalHandlers) {
4347 if (PrintJNIResolving) {
4348 tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled");
4349 }
4350 check_signals = false;
4351 }
4352 }
4353 }
4354 }
4355
4356 // This is the fastest way to get thread cpu time on Linux.
4357 // Returns cpu time (user+sys) for any thread, not only for current.
4358 // POSIX compliant clocks are implemented in the kernels 2.6.16+.
4359 // It might work on 2.6.10+ with a special kernel/glibc patch.
4360 // For reference, please, see IEEE Std 1003.1-2004:
4361 // http://www.unix.org/single_unix_specification
4362
4363 jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) {
4364 struct timespec tp;
4365 int rc = os::Linux::clock_gettime(clockid, &tp);
4366 assert(rc == 0, "clock_gettime is expected to return 0 code");
4367
4368 return (tp.tv_sec * NANOSECS_PER_SEC) + tp.tv_nsec;
4369 }
4370
4371 /////
4372 // glibc on Linux platform uses non-documented flag
4373 // to indicate, that some special sort of signal
4374 // trampoline is used.
4375 // We will never set this flag, and we should
4376 // ignore this flag in our diagnostic
4377 #ifdef SIGNIFICANT_SIGNAL_MASK
4378 #undef SIGNIFICANT_SIGNAL_MASK
4379 #endif
4380 #define SIGNIFICANT_SIGNAL_MASK (~0x04000000)
4381
4382 static const char* get_signal_handler_name(address handler,
4383 char* buf, int buflen) {
4384 int offset;
4385 bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset);
4386 if (found) {
4387 // skip directory names
4388 const char *p1, *p2;
4389 p1 = buf;
4390 size_t len = strlen(os::file_separator());
4391 while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len;
4392 jio_snprintf(buf, buflen, "%s+0x%x", p1, offset);
4393 } else {
4394 jio_snprintf(buf, buflen, PTR_FORMAT, handler);
4395 }
4396 return buf;
4397 }
4398
4399 static void print_signal_handler(outputStream* st, int sig,
4400 char* buf, size_t buflen) {
4401 struct sigaction sa;
4402
4403 sigaction(sig, NULL, &sa);
4404
4405 // See comment for SIGNIFICANT_SIGNAL_MASK define
4406 sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
4407
4408 st->print("%s: ", os::exception_name(sig, buf, buflen));
4409
4410 address handler = (sa.sa_flags & SA_SIGINFO)
4411 ? CAST_FROM_FN_PTR(address, sa.sa_sigaction)
4412 : CAST_FROM_FN_PTR(address, sa.sa_handler);
4413
4414 if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) {
4415 st->print("SIG_DFL");
4416 } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) {
4417 st->print("SIG_IGN");
4418 } else {
4419 st->print("[%s]", get_signal_handler_name(handler, buf, buflen));
4420 }
4421
4422 st->print(", sa_mask[0]=");
4423 os::Posix::print_signal_set_short(st, &sa.sa_mask);
4424
4425 address rh = VMError::get_resetted_sighandler(sig);
4426 // May be, handler was resetted by VMError?
4427 if (rh != NULL) {
4428 handler = rh;
4429 sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK;
4430 }
4431
4432 st->print(", sa_flags=");
4433 os::Posix::print_sa_flags(st, sa.sa_flags);
4434
4435 // Check: is it our handler?
4436 if (handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) ||
4437 handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) {
4438 // It is our signal handler
4439 // check for flags, reset system-used one!
4440 if ((int)sa.sa_flags != os::Linux::get_our_sigflags(sig)) {
4441 st->print(
4442 ", flags was changed from " PTR32_FORMAT ", consider using jsig library",
4443 os::Linux::get_our_sigflags(sig));
4444 }
4445 }
4446 st->cr();
4447 }
4448
4449
4450 #define DO_SIGNAL_CHECK(sig) \
4451 if (!sigismember(&check_signal_done, sig)) \
4452 os::Linux::check_signal_handler(sig)
4453
4454 // This method is a periodic task to check for misbehaving JNI applications
4455 // under CheckJNI, we can add any periodic checks here
4456
4457 void os::run_periodic_checks() {
4458
4459 if (check_signals == false) return;
4460
4461 // SEGV and BUS if overridden could potentially prevent
4462 // generation of hs*.log in the event of a crash, debugging
4463 // such a case can be very challenging, so we absolutely
4464 // check the following for a good measure:
4465 DO_SIGNAL_CHECK(SIGSEGV);
4466 DO_SIGNAL_CHECK(SIGILL);
4467 DO_SIGNAL_CHECK(SIGFPE);
4468 DO_SIGNAL_CHECK(SIGBUS);
4469 DO_SIGNAL_CHECK(SIGPIPE);
4470 DO_SIGNAL_CHECK(SIGXFSZ);
4471 #if defined(PPC64)
4472 DO_SIGNAL_CHECK(SIGTRAP);
4473 #endif
4474
4475 // ReduceSignalUsage allows the user to override these handlers
4476 // see comments at the very top and jvm_solaris.h
4477 if (!ReduceSignalUsage) {
4478 DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL);
4479 DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL);
4480 DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL);
4481 DO_SIGNAL_CHECK(BREAK_SIGNAL);
4482 }
4483
4484 DO_SIGNAL_CHECK(SR_signum);
4485 DO_SIGNAL_CHECK(INTERRUPT_SIGNAL);
4486 }
4487
4488 typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *);
4489
4490 static os_sigaction_t os_sigaction = NULL;
4491
4492 void os::Linux::check_signal_handler(int sig) {
4493 char buf[O_BUFLEN];
4494 address jvmHandler = NULL;
4495
4496
4497 struct sigaction act;
4498 if (os_sigaction == NULL) {
4499 // only trust the default sigaction, in case it has been interposed
4500 os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction");
4501 if (os_sigaction == NULL) return;
4502 }
4503
4504 os_sigaction(sig, (struct sigaction*)NULL, &act);
4505
4506
4507 act.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
4508
4509 address thisHandler = (act.sa_flags & SA_SIGINFO)
4510 ? CAST_FROM_FN_PTR(address, act.sa_sigaction)
4511 : CAST_FROM_FN_PTR(address, act.sa_handler);
4512
4513
4514 switch (sig) {
4515 case SIGSEGV:
4516 case SIGBUS:
4517 case SIGFPE:
4518 case SIGPIPE:
4519 case SIGILL:
4520 case SIGXFSZ:
4521 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler);
4522 break;
4523
4524 case SHUTDOWN1_SIGNAL:
4525 case SHUTDOWN2_SIGNAL:
4526 case SHUTDOWN3_SIGNAL:
4527 case BREAK_SIGNAL:
4528 jvmHandler = (address)user_handler();
4529 break;
4530
4531 case INTERRUPT_SIGNAL:
4532 jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL);
4533 break;
4534
4535 default:
4536 if (sig == SR_signum) {
4537 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler);
4538 } else {
4539 return;
4540 }
4541 break;
4542 }
4543
4544 if (thisHandler != jvmHandler) {
4545 tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN));
4546 tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN));
4547 tty->print_cr(" found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN));
4548 // No need to check this sig any longer
4549 sigaddset(&check_signal_done, sig);
4550 // Running under non-interactive shell, SHUTDOWN2_SIGNAL will be reassigned SIG_IGN
4551 if (sig == SHUTDOWN2_SIGNAL && !isatty(fileno(stdin))) {
4552 tty->print_cr("Running in non-interactive shell, %s handler is replaced by shell",
4553 exception_name(sig, buf, O_BUFLEN));
4554 }
4555 } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) {
4556 tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN));
4557 tty->print("expected:" PTR32_FORMAT, os::Linux::get_our_sigflags(sig));
4558 tty->print_cr(" found:" PTR32_FORMAT, act.sa_flags);
4559 // No need to check this sig any longer
4560 sigaddset(&check_signal_done, sig);
4561 }
4562
4563 // Dump all the signal
4564 if (sigismember(&check_signal_done, sig)) {
4565 print_signal_handlers(tty, buf, O_BUFLEN);
4566 }
4567 }
4568
4569 extern void report_error(char* file_name, int line_no, char* title, char* format, ...);
4570
4571 extern bool signal_name(int signo, char* buf, size_t len);
4572
4573 const char* os::exception_name(int exception_code, char* buf, size_t size) {
4574 if (0 < exception_code && exception_code <= SIGRTMAX) {
4575 // signal
4576 if (!signal_name(exception_code, buf, size)) {
4577 jio_snprintf(buf, size, "SIG%d", exception_code);
4578 }
4579 return buf;
4580 } else {
4581 return NULL;
4582 }
4583 }
4584
4585 // this is called _before_ the most of global arguments have been parsed
4586 void os::init(void) {
4587 char dummy; /* used to get a guess on initial stack address */
4588 // first_hrtime = gethrtime();
4589
4590 // With LinuxThreads the JavaMain thread pid (primordial thread)
4591 // is different than the pid of the java launcher thread.
4592 // So, on Linux, the launcher thread pid is passed to the VM
4593 // via the sun.java.launcher.pid property.
4594 // Use this property instead of getpid() if it was correctly passed.
4595 // See bug 6351349.
4596 pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid();
4597
4598 _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid();
4599
4600 clock_tics_per_sec = sysconf(_SC_CLK_TCK);
4601
4602 init_random(1234567);
4603
4604 ThreadCritical::initialize();
4605
4606 Linux::set_page_size(sysconf(_SC_PAGESIZE));
4607 if (Linux::page_size() == -1) {
4608 fatal(err_msg("os_linux.cpp: os::init: sysconf failed (%s)",
4609 strerror(errno)));
4610 }
4611 init_page_sizes((size_t) Linux::page_size());
4612
4613 Linux::initialize_system_info();
4614
4615 // main_thread points to the aboriginal thread
4616 Linux::_main_thread = pthread_self();
4617
4618 Linux::clock_init();
4619 initial_time_count = javaTimeNanos();
4620
4621 // pthread_condattr initialization for monotonic clock
4622 int status;
4623 pthread_condattr_t* _condattr = os::Linux::condAttr();
4624 if ((status = pthread_condattr_init(_condattr)) != 0) {
4625 fatal(err_msg("pthread_condattr_init: %s", strerror(status)));
4626 }
4627 // Only set the clock if CLOCK_MONOTONIC is available
4628 if (os::supports_monotonic_clock()) {
4629 if ((status = pthread_condattr_setclock(_condattr, CLOCK_MONOTONIC)) != 0) {
4630 if (status == EINVAL) {
4631 warning("Unable to use monotonic clock with relative timed-waits" \
4632 " - changes to the time-of-day clock may have adverse affects");
4633 } else {
4634 fatal(err_msg("pthread_condattr_setclock: %s", strerror(status)));
4635 }
4636 }
4637 }
4638 // else it defaults to CLOCK_REALTIME
4639
4640 pthread_mutex_init(&dl_mutex, NULL);
4641
4642 // If the pagesize of the VM is greater than 8K determine the appropriate
4643 // number of initial guard pages. The user can change this with the
4644 // command line arguments, if needed.
4645 if (vm_page_size() > (int)Linux::vm_default_page_size()) {
4646 StackYellowPages = 1;
4647 StackRedPages = 1;
4648 StackShadowPages = round_to((StackShadowPages*Linux::vm_default_page_size()), vm_page_size()) / vm_page_size();
4649 }
4650 }
4651
4652 // To install functions for atexit system call
4653 extern "C" {
4654 static void perfMemory_exit_helper() {
4655 perfMemory_exit();
4656 }
4657 }
4658
4659 // this is called _after_ the global arguments have been parsed
4660 jint os::init_2(void)
4661 {
4662 Linux::fast_thread_clock_init();
4663
4664 // Allocate a single page and mark it as readable for safepoint polling
4665 address polling_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
4666 guarantee(polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page");
4667
4668 os::set_polling_page(polling_page);
4669
4670 #ifndef PRODUCT
4671 if (Verbose && PrintMiscellaneous)
4672 tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n", (intptr_t)polling_page);
4673 #endif
4674
4675 if (!UseMembar) {
4676 address mem_serialize_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
4677 guarantee(mem_serialize_page != MAP_FAILED, "mmap Failed for memory serialize page");
4678 os::set_memory_serialize_page(mem_serialize_page);
4679
4680 #ifndef PRODUCT
4681 if (Verbose && PrintMiscellaneous)
4682 tty->print("[Memory Serialize Page address: " INTPTR_FORMAT "]\n", (intptr_t)mem_serialize_page);
4683 #endif
4684 }
4685
4686 // initialize suspend/resume support - must do this before signal_sets_init()
4687 if (SR_initialize() != 0) {
4688 perror("SR_initialize failed");
4689 return JNI_ERR;
4690 }
4691
4692 Linux::signal_sets_init();
4693 Linux::install_signal_handlers();
4694
4695 // Check minimum allowable stack size for thread creation and to initialize
4696 // the java system classes, including StackOverflowError - depends on page
4697 // size. Add a page for compiler2 recursion in main thread.
4698 // Add in 2*BytesPerWord times page size to account for VM stack during
4699 // class initialization depending on 32 or 64 bit VM.
4700 os::Linux::min_stack_allowed = MAX2(os::Linux::min_stack_allowed,
4701 (size_t)(StackYellowPages+StackRedPages+StackShadowPages) * Linux::page_size() +
4702 (2*BytesPerWord COMPILER2_PRESENT(+1)) * Linux::vm_default_page_size());
4703
4704 size_t threadStackSizeInBytes = ThreadStackSize * K;
4705 if (threadStackSizeInBytes != 0 &&
4706 threadStackSizeInBytes < os::Linux::min_stack_allowed) {
4707 tty->print_cr("\nThe stack size specified is too small, "
4708 "Specify at least %dk",
4709 os::Linux::min_stack_allowed/ K);
4710 return JNI_ERR;
4711 }
4712
4713 // Make the stack size a multiple of the page size so that
4714 // the yellow/red zones can be guarded.
4715 JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes,
4716 vm_page_size()));
4717
4718 Linux::capture_initial_stack(JavaThread::stack_size_at_create());
4719
4720 #if defined(IA32)
4721 workaround_expand_exec_shield_cs_limit();
4722 #endif
4723
4724 Linux::libpthread_init();
4725 if (PrintMiscellaneous && (Verbose || WizardMode)) {
4726 tty->print_cr("[HotSpot is running with %s, %s(%s)]\n",
4727 Linux::glibc_version(), Linux::libpthread_version(),
4728 Linux::is_floating_stack() ? "floating stack" : "fixed stack");
4729 }
4730
4731 if (UseNUMA) {
4732 if (!Linux::libnuma_init()) {
4733 UseNUMA = false;
4734 } else {
4735 if ((Linux::numa_max_node() < 1)) {
4736 // There's only one node(they start from 0), disable NUMA.
4737 UseNUMA = false;
4738 }
4739 }
4740 // With SHM and HugeTLBFS large pages we cannot uncommit a page, so there's no way
4741 // we can make the adaptive lgrp chunk resizing work. If the user specified
4742 // both UseNUMA and UseLargePages (or UseSHM/UseHugeTLBFS) on the command line - warn and
4743 // disable adaptive resizing.
4744 if (UseNUMA && UseLargePages && !can_commit_large_page_memory()) {
4745 if (FLAG_IS_DEFAULT(UseNUMA)) {
4746 UseNUMA = false;
4747 } else {
4748 if (FLAG_IS_DEFAULT(UseLargePages) &&
4749 FLAG_IS_DEFAULT(UseSHM) &&
4750 FLAG_IS_DEFAULT(UseHugeTLBFS)) {
4751 UseLargePages = false;
4752 } else {
4753 warning("UseNUMA is not fully compatible with SHM/HugeTLBFS large pages, disabling adaptive resizing");
4754 UseAdaptiveSizePolicy = false;
4755 UseAdaptiveNUMAChunkSizing = false;
4756 }
4757 }
4758 }
4759 if (!UseNUMA && ForceNUMA) {
4760 UseNUMA = true;
4761 }
4762 }
4763
4764 if (MaxFDLimit) {
4765 // set the number of file descriptors to max. print out error
4766 // if getrlimit/setrlimit fails but continue regardless.
4767 struct rlimit nbr_files;
4768 int status = getrlimit(RLIMIT_NOFILE, &nbr_files);
4769 if (status != 0) {
4770 if (PrintMiscellaneous && (Verbose || WizardMode))
4771 perror("os::init_2 getrlimit failed");
4772 } else {
4773 nbr_files.rlim_cur = nbr_files.rlim_max;
4774 status = setrlimit(RLIMIT_NOFILE, &nbr_files);
4775 if (status != 0) {
4776 if (PrintMiscellaneous && (Verbose || WizardMode))
4777 perror("os::init_2 setrlimit failed");
4778 }
4779 }
4780 }
4781
4782 // Initialize lock used to serialize thread creation (see os::create_thread)
4783 Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false));
4784
4785 // at-exit methods are called in the reverse order of their registration.
4786 // atexit functions are called on return from main or as a result of a
4787 // call to exit(3C). There can be only 32 of these functions registered
4788 // and atexit() does not set errno.
4789
4790 if (PerfAllowAtExitRegistration) {
4791 // only register atexit functions if PerfAllowAtExitRegistration is set.
4792 // atexit functions can be delayed until process exit time, which
4793 // can be problematic for embedded VM situations. Embedded VMs should
4794 // call DestroyJavaVM() to assure that VM resources are released.
4795
4796 // note: perfMemory_exit_helper atexit function may be removed in
4797 // the future if the appropriate cleanup code can be added to the
4798 // VM_Exit VMOperation's doit method.
4799 if (atexit(perfMemory_exit_helper) != 0) {
4800 warning("os::init_2 atexit(perfMemory_exit_helper) failed");
4801 }
4802 }
4803
4804 // initialize thread priority policy
4805 prio_init();
4806
4807 return JNI_OK;
4808 }
4809
4810 // this is called at the end of vm_initialization
4811 void os::init_3(void) {
4812 #ifdef JAVASE_EMBEDDED
4813 // Start the MemNotifyThread
4814 if (LowMemoryProtection) {
4815 MemNotifyThread::start();
4816 }
4817 return;
4818 #endif
4819 }
4820
4821 // Mark the polling page as unreadable
4822 void os::make_polling_page_unreadable(void) {
4823 if (!guard_memory((char*)_polling_page, Linux::page_size()))
4824 fatal("Could not disable polling page");
4825 };
4826
4827 // Mark the polling page as readable
4828 void os::make_polling_page_readable(void) {
4829 if (!linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) {
4830 fatal("Could not enable polling page");
4831 }
4832 };
4833
4834 int os::active_processor_count() {
4835 // Linux doesn't yet have a (official) notion of processor sets,
4836 // so just return the number of online processors.
4837 int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN);
4838 assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check");
4839 return online_cpus;
4840 }
4841
4842 void os::set_native_thread_name(const char *name) {
4843 // Not yet implemented.
4844 return;
4845 }
4846
4847 bool os::distribute_processes(uint length, uint* distribution) {
4848 // Not yet implemented.
4849 return false;
4850 }
4851
4852 bool os::bind_to_processor(uint processor_id) {
4853 // Not yet implemented.
4854 return false;
4855 }
4856
4857 ///
4858
4859 void os::SuspendedThreadTask::internal_do_task() {
4860 if (do_suspend(_thread->osthread())) {
4861 SuspendedThreadTaskContext context(_thread, _thread->osthread()->ucontext());
4862 do_task(context);
4863 do_resume(_thread->osthread());
4864 }
4865 }
4866
4867 class PcFetcher : public os::SuspendedThreadTask {
4868 public:
4869 PcFetcher(Thread* thread) : os::SuspendedThreadTask(thread) {}
4870 ExtendedPC result();
4871 protected:
4872 void do_task(const os::SuspendedThreadTaskContext& context);
4873 private:
4874 ExtendedPC _epc;
4875 };
4876
4877 ExtendedPC PcFetcher::result() {
4878 guarantee(is_done(), "task is not done yet.");
4879 return _epc;
4880 }
4881
4882 void PcFetcher::do_task(const os::SuspendedThreadTaskContext& context) {
4883 Thread* thread = context.thread();
4884 OSThread* osthread = thread->osthread();
4885 if (osthread->ucontext() != NULL) {
4886 _epc = os::Linux::ucontext_get_pc((ucontext_t *) context.ucontext());
4887 } else {
4888 // NULL context is unexpected, double-check this is the VMThread
4889 guarantee(thread->is_VM_thread(), "can only be called for VMThread");
4890 }
4891 }
4892
4893 // Suspends the target using the signal mechanism and then grabs the PC before
4894 // resuming the target. Used by the flat-profiler only
4895 ExtendedPC os::get_thread_pc(Thread* thread) {
4896 // Make sure that it is called by the watcher for the VMThread
4897 assert(Thread::current()->is_Watcher_thread(), "Must be watcher");
4898 assert(thread->is_VM_thread(), "Can only be called for VMThread");
4899
4900 PcFetcher fetcher(thread);
4901 fetcher.run();
4902 return fetcher.result();
4903 }
4904
4905 int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond, pthread_mutex_t *_mutex, const struct timespec *_abstime)
4906 {
4907 if (is_NPTL()) {
4908 return pthread_cond_timedwait(_cond, _mutex, _abstime);
4909 } else {
4910 // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control
4911 // word back to default 64bit precision if condvar is signaled. Java
4912 // wants 53bit precision. Save and restore current value.
4913 int fpu = get_fpu_control_word();
4914 int status = pthread_cond_timedwait(_cond, _mutex, _abstime);
4915 set_fpu_control_word(fpu);
4916 return status;
4917 }
4918 }
4919
4920 ////////////////////////////////////////////////////////////////////////////////
4921 // debug support
4922
4923 bool os::find(address addr, outputStream* st) {
4924 Dl_info dlinfo;
4925 memset(&dlinfo, 0, sizeof(dlinfo));
4926 if (dladdr(addr, &dlinfo) != 0) {
4927 st->print(PTR_FORMAT ": ", addr);
4928 if (dlinfo.dli_sname != NULL && dlinfo.dli_saddr != NULL) {
4929 st->print("%s+%#x", dlinfo.dli_sname,
4930 addr - (intptr_t)dlinfo.dli_saddr);
4931 } else if (dlinfo.dli_fbase != NULL) {
4932 st->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase);
4933 } else {
4934 st->print("<absolute address>");
4935 }
4936 if (dlinfo.dli_fname != NULL) {
4937 st->print(" in %s", dlinfo.dli_fname);
4938 }
4939 if (dlinfo.dli_fbase != NULL) {
4940 st->print(" at " PTR_FORMAT, dlinfo.dli_fbase);
4941 }
4942 st->cr();
4943
4944 if (Verbose) {
4945 // decode some bytes around the PC
4946 address begin = clamp_address_in_page(addr-40, addr, os::vm_page_size());
4947 address end = clamp_address_in_page(addr+40, addr, os::vm_page_size());
4948 address lowest = (address) dlinfo.dli_sname;
4949 if (!lowest) lowest = (address) dlinfo.dli_fbase;
4950 if (begin < lowest) begin = lowest;
4951 Dl_info dlinfo2;
4952 if (dladdr(end, &dlinfo2) != 0 && dlinfo2.dli_saddr != dlinfo.dli_saddr
4953 && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin)
4954 end = (address) dlinfo2.dli_saddr;
4955 Disassembler::decode(begin, end, st);
4956 }
4957 return true;
4958 }
4959 return false;
4960 }
4961
4962 ////////////////////////////////////////////////////////////////////////////////
4963 // misc
4964
4965 // This does not do anything on Linux. This is basically a hook for being
4966 // able to use structured exception handling (thread-local exception filters)
4967 // on, e.g., Win32.
4968 void
4969 os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method,
4970 JavaCallArguments* args, Thread* thread) {
4971 f(value, method, args, thread);
4972 }
4973
4974 void os::print_statistics() {
4975 }
4976
4977 int os::message_box(const char* title, const char* message) {
4978 int i;
4979 fdStream err(defaultStream::error_fd());
4980 for (i = 0; i < 78; i++) err.print_raw("=");
4981 err.cr();
4982 err.print_raw_cr(title);
4983 for (i = 0; i < 78; i++) err.print_raw("-");
4984 err.cr();
4985 err.print_raw_cr(message);
4986 for (i = 0; i < 78; i++) err.print_raw("=");
4987 err.cr();
4988
4989 char buf[16];
4990 // Prevent process from exiting upon "read error" without consuming all CPU
4991 while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); }
4992
4993 return buf[0] == 'y' || buf[0] == 'Y';
4994 }
4995
4996 int os::stat(const char *path, struct stat *sbuf) {
4997 char pathbuf[MAX_PATH];
4998 if (strlen(path) > MAX_PATH - 1) {
4999 errno = ENAMETOOLONG;
5000 return -1;
5001 }
5002 os::native_path(strcpy(pathbuf, path));
5003 return ::stat(pathbuf, sbuf);
5004 }
5005
5006 bool os::check_heap(bool force) {
5007 return true;
5008 }
5009
5010 int local_vsnprintf(char* buf, size_t count, const char* format, va_list args) {
5011 return ::vsnprintf(buf, count, format, args);
5012 }
5013
5014 // Is a (classpath) directory empty?
5015 bool os::dir_is_empty(const char* path) {
5016 DIR *dir = NULL;
5017 struct dirent *ptr;
5018
5019 dir = opendir(path);
5020 if (dir == NULL) return true;
5021
5022 /* Scan the directory */
5023 bool result = true;
5024 char buf[sizeof(struct dirent) + MAX_PATH];
5025 while (result && (ptr = ::readdir(dir)) != NULL) {
5026 if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) {
5027 result = false;
5028 }
5029 }
5030 closedir(dir);
5031 return result;
5032 }
5033
5034 // This code originates from JDK's sysOpen and open64_w
5035 // from src/solaris/hpi/src/system_md.c
5036
5037 #ifndef O_DELETE
5038 #define O_DELETE 0x10000
5039 #endif
5040
5041 // Open a file. Unlink the file immediately after open returns
5042 // if the specified oflag has the O_DELETE flag set.
5043 // O_DELETE is used only in j2se/src/share/native/java/util/zip/ZipFile.c
5044
5045 int os::open(const char *path, int oflag, int mode) {
5046
5047 if (strlen(path) > MAX_PATH - 1) {
5048 errno = ENAMETOOLONG;
5049 return -1;
5050 }
5051 int fd;
5052 int o_delete = (oflag & O_DELETE);
5053 oflag = oflag & ~O_DELETE;
5054
5055 fd = ::open64(path, oflag, mode);
5056 if (fd == -1) return -1;
5057
5058 //If the open succeeded, the file might still be a directory
5059 {
5060 struct stat64 buf64;
5061 int ret = ::fstat64(fd, &buf64);
5062 int st_mode = buf64.st_mode;
5063
5064 if (ret != -1) {
5065 if ((st_mode & S_IFMT) == S_IFDIR) {
5066 errno = EISDIR;
5067 ::close(fd);
5068 return -1;
5069 }
5070 } else {
5071 ::close(fd);
5072 return -1;
5073 }
5074 }
5075
5076 /*
5077 * All file descriptors that are opened in the JVM and not
5078 * specifically destined for a subprocess should have the
5079 * close-on-exec flag set. If we don't set it, then careless 3rd
5080 * party native code might fork and exec without closing all
5081 * appropriate file descriptors (e.g. as we do in closeDescriptors in
5082 * UNIXProcess.c), and this in turn might:
5083 *
5084 * - cause end-of-file to fail to be detected on some file
5085 * descriptors, resulting in mysterious hangs, or
5086 *
5087 * - might cause an fopen in the subprocess to fail on a system
5088 * suffering from bug 1085341.
5089 *
5090 * (Yes, the default setting of the close-on-exec flag is a Unix
5091 * design flaw)
5092 *
5093 * See:
5094 * 1085341: 32-bit stdio routines should support file descriptors >255
5095 * 4843136: (process) pipe file descriptor from Runtime.exec not being closed
5096 * 6339493: (process) Runtime.exec does not close all file descriptors on Solaris 9
5097 */
5098 #ifdef FD_CLOEXEC
5099 {
5100 int flags = ::fcntl(fd, F_GETFD);
5101 if (flags != -1)
5102 ::fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
5103 }
5104 #endif
5105
5106 if (o_delete != 0) {
5107 ::unlink(path);
5108 }
5109 return fd;
5110 }
5111
5112
5113 // create binary file, rewriting existing file if required
5114 int os::create_binary_file(const char* path, bool rewrite_existing) {
5115 int oflags = O_WRONLY | O_CREAT;
5116 if (!rewrite_existing) {
5117 oflags |= O_EXCL;
5118 }
5119 return ::open64(path, oflags, S_IREAD | S_IWRITE);
5120 }
5121
5122 // return current position of file pointer
5123 jlong os::current_file_offset(int fd) {
5124 return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR);
5125 }
5126
5127 // move file pointer to the specified offset
5128 jlong os::seek_to_file_offset(int fd, jlong offset) {
5129 return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET);
5130 }
5131
5132 // This code originates from JDK's sysAvailable
5133 // from src/solaris/hpi/src/native_threads/src/sys_api_td.c
5134
5135 int os::available(int fd, jlong *bytes) {
5136 jlong cur, end;
5137 int mode;
5138 struct stat64 buf64;
5139
5140 if (::fstat64(fd, &buf64) >= 0) {
5141 mode = buf64.st_mode;
5142 if (S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) {
5143 /*
5144 * XXX: is the following call interruptible? If so, this might
5145 * need to go through the INTERRUPT_IO() wrapper as for other
5146 * blocking, interruptible calls in this file.
5147 */
5148 int n;
5149 if (::ioctl(fd, FIONREAD, &n) >= 0) {
5150 *bytes = n;
5151 return 1;
5152 }
5153 }
5154 }
5155 if ((cur = ::lseek64(fd, 0L, SEEK_CUR)) == -1) {
5156 return 0;
5157 } else if ((end = ::lseek64(fd, 0L, SEEK_END)) == -1) {
5158 return 0;
5159 } else if (::lseek64(fd, cur, SEEK_SET) == -1) {
5160 return 0;
5161 }
5162 *bytes = end - cur;
5163 return 1;
5164 }
5165
5166 int os::socket_available(int fd, jint *pbytes) {
5167 // Linux doc says EINTR not returned, unlike Solaris
5168 int ret = ::ioctl(fd, FIONREAD, pbytes);
5169
5170 //%% note ioctl can return 0 when successful, JVM_SocketAvailable
5171 // is expected to return 0 on failure and 1 on success to the jdk.
5172 return (ret < 0) ? 0 : 1;
5173 }
5174
5175 // Map a block of memory.
5176 char* os::pd_map_memory(int fd, const char* file_name, size_t file_offset,
5177 char *addr, size_t bytes, bool read_only,
5178 bool allow_exec) {
5179 int prot;
5180 int flags = MAP_PRIVATE;
5181
5182 if (read_only) {
5183 prot = PROT_READ;
5184 } else {
5185 prot = PROT_READ | PROT_WRITE;
5186 }
5187
5188 if (allow_exec) {
5189 prot |= PROT_EXEC;
5190 }
5191
5192 if (addr != NULL) {
5193 flags |= MAP_FIXED;
5194 }
5195
5196 char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags,
5197 fd, file_offset);
5198 if (mapped_address == MAP_FAILED) {
5199 return NULL;
5200 }
5201 return mapped_address;
5202 }
5203
5204
5205 // Remap a block of memory.
5206 char* os::pd_remap_memory(int fd, const char* file_name, size_t file_offset,
5207 char *addr, size_t bytes, bool read_only,
5208 bool allow_exec) {
5209 // same as map_memory() on this OS
5210 return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only,
5211 allow_exec);
5212 }
5213
5214
5215 // Unmap a block of memory.
5216 bool os::pd_unmap_memory(char* addr, size_t bytes) {
5217 return munmap(addr, bytes) == 0;
5218 }
5219
5220 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time);
5221
5222 static clockid_t thread_cpu_clockid(Thread* thread) {
5223 pthread_t tid = thread->osthread()->pthread_id();
5224 clockid_t clockid;
5225
5226 // Get thread clockid
5227 int rc = os::Linux::pthread_getcpuclockid(tid, &clockid);
5228 assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code");
5229 return clockid;
5230 }
5231
5232 // current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool)
5233 // are used by JVM M&M and JVMTI to get user+sys or user CPU time
5234 // of a thread.
5235 //
5236 // current_thread_cpu_time() and thread_cpu_time(Thread*) returns
5237 // the fast estimate available on the platform.
5238
5239 jlong os::current_thread_cpu_time() {
5240 if (os::Linux::supports_fast_thread_cpu_time()) {
5241 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
5242 } else {
5243 // return user + sys since the cost is the same
5244 return slow_thread_cpu_time(Thread::current(), true /* user + sys */);
5245 }
5246 }
5247
5248 jlong os::thread_cpu_time(Thread* thread) {
5249 // consistent with what current_thread_cpu_time() returns
5250 if (os::Linux::supports_fast_thread_cpu_time()) {
5251 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread));
5252 } else {
5253 return slow_thread_cpu_time(thread, true /* user + sys */);
5254 }
5255 }
5256
5257 jlong os::current_thread_cpu_time(bool user_sys_cpu_time) {
5258 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
5259 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
5260 } else {
5261 return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time);
5262 }
5263 }
5264
5265 jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
5266 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
5267 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread));
5268 } else {
5269 return slow_thread_cpu_time(thread, user_sys_cpu_time);
5270 }
5271 }
5272
5273 //
5274 // -1 on error.
5275 //
5276
5277 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
5278 pid_t tid = thread->osthread()->thread_id();
5279 char *s;
5280 char stat[2048];
5281 int statlen;
5282 char proc_name[64];
5283 int count;
5284 long sys_time, user_time;
5285 char cdummy;
5286 int idummy;
5287 long ldummy;
5288 FILE *fp;
5289
5290 snprintf(proc_name, 64, "/proc/self/task/%d/stat", tid);
5291 fp = fopen(proc_name, "r");
5292 if (fp == NULL) return -1;
5293 statlen = fread(stat, 1, 2047, fp);
5294 stat[statlen] = '\0';
5295 fclose(fp);
5296
5297 // Skip pid and the command string. Note that we could be dealing with
5298 // weird command names, e.g. user could decide to rename java launcher
5299 // to "java 1.4.2 :)", then the stat file would look like
5300 // 1234 (java 1.4.2 :)) R ... ...
5301 // We don't really need to know the command string, just find the last
5302 // occurrence of ")" and then start parsing from there. See bug 4726580.
5303 s = strrchr(stat, ')');
5304 if (s == NULL) return -1;
5305
5306 // Skip blank chars
5307 do s++; while (isspace(*s));
5308
5309 count = sscanf(s,"%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu",
5310 &cdummy, &idummy, &idummy, &idummy, &idummy, &idummy,
5311 &ldummy, &ldummy, &ldummy, &ldummy, &ldummy,
5312 &user_time, &sys_time);
5313 if (count != 13) return -1;
5314 if (user_sys_cpu_time) {
5315 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec);
5316 } else {
5317 return (jlong)user_time * (1000000000 / clock_tics_per_sec);
5318 }
5319 }
5320
5321 void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
5322 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits
5323 info_ptr->may_skip_backward = false; // elapsed time not wall time
5324 info_ptr->may_skip_forward = false; // elapsed time not wall time
5325 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned
5326 }
5327
5328 void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
5329 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits
5330 info_ptr->may_skip_backward = false; // elapsed time not wall time
5331 info_ptr->may_skip_forward = false; // elapsed time not wall time
5332 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned
5333 }
5334
5335 bool os::is_thread_cpu_time_supported() {
5336 return true;
5337 }
5338
5339 // System loadavg support. Returns -1 if load average cannot be obtained.
5340 // Linux doesn't yet have a (official) notion of processor sets,
5341 // so just return the system wide load average.
5342 int os::loadavg(double loadavg[], int nelem) {
5343 return ::getloadavg(loadavg, nelem);
5344 }
5345
5346 void os::pause() {
5347 char filename[MAX_PATH];
5348 if (PauseAtStartupFile && PauseAtStartupFile[0]) {
5349 jio_snprintf(filename, MAX_PATH, PauseAtStartupFile);
5350 } else {
5351 jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id());
5352 }
5353
5354 int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
5355 if (fd != -1) {
5356 struct stat buf;
5357 ::close(fd);
5358 while (::stat(filename, &buf) == 0) {
5359 (void)::poll(NULL, 0, 100);
5360 }
5361 } else {
5362 jio_fprintf(stderr,
5363 "Could not open pause file '%s', continuing immediately.\n", filename);
5364 }
5365 }
5366
5367
5368 // Refer to the comments in os_solaris.cpp park-unpark.
5369 //
5370 // Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can
5371 // hang indefinitely. For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable.
5372 // For specifics regarding the bug see GLIBC BUGID 261237 :
5373 // http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html.
5374 // Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future
5375 // will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar
5376 // is used. (The simple C test-case provided in the GLIBC bug report manifests the
5377 // hang). The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos()
5378 // and monitorenter when we're using 1-0 locking. All those operations may result in
5379 // calls to pthread_cond_timedwait(). Using LD_ASSUME_KERNEL to use an older version
5380 // of libpthread avoids the problem, but isn't practical.
5381 //
5382 // Possible remedies:
5383 //
5384 // 1. Establish a minimum relative wait time. 50 to 100 msecs seems to work.
5385 // This is palliative and probabilistic, however. If the thread is preempted
5386 // between the call to compute_abstime() and pthread_cond_timedwait(), more
5387 // than the minimum period may have passed, and the abstime may be stale (in the
5388 // past) resultin in a hang. Using this technique reduces the odds of a hang
5389 // but the JVM is still vulnerable, particularly on heavily loaded systems.
5390 //
5391 // 2. Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead
5392 // of the usual flag-condvar-mutex idiom. The write side of the pipe is set
5393 // NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo)
5394 // reduces to poll()+read(). This works well, but consumes 2 FDs per extant
5395 // thread.
5396 //
5397 // 3. Embargo pthread_cond_timedwait() and implement a native "chron" thread
5398 // that manages timeouts. We'd emulate pthread_cond_timedwait() by enqueuing
5399 // a timeout request to the chron thread and then blocking via pthread_cond_wait().
5400 // This also works well. In fact it avoids kernel-level scalability impediments
5401 // on certain platforms that don't handle lots of active pthread_cond_timedwait()
5402 // timers in a graceful fashion.
5403 //
5404 // 4. When the abstime value is in the past it appears that control returns
5405 // correctly from pthread_cond_timedwait(), but the condvar is left corrupt.
5406 // Subsequent timedwait/wait calls may hang indefinitely. Given that, we
5407 // can avoid the problem by reinitializing the condvar -- by cond_destroy()
5408 // followed by cond_init() -- after all calls to pthread_cond_timedwait().
5409 // It may be possible to avoid reinitialization by checking the return
5410 // value from pthread_cond_timedwait(). In addition to reinitializing the
5411 // condvar we must establish the invariant that cond_signal() is only called
5412 // within critical sections protected by the adjunct mutex. This prevents
5413 // cond_signal() from "seeing" a condvar that's in the midst of being
5414 // reinitialized or that is corrupt. Sadly, this invariant obviates the
5415 // desirable signal-after-unlock optimization that avoids futile context switching.
5416 //
5417 // I'm also concerned that some versions of NTPL might allocate an auxilliary
5418 // structure when a condvar is used or initialized. cond_destroy() would
5419 // release the helper structure. Our reinitialize-after-timedwait fix
5420 // put excessive stress on malloc/free and locks protecting the c-heap.
5421 //
5422 // We currently use (4). See the WorkAroundNTPLTimedWaitHang flag.
5423 // It may be possible to refine (4) by checking the kernel and NTPL verisons
5424 // and only enabling the work-around for vulnerable environments.
5425
5426 // utility to compute the abstime argument to timedwait:
5427 // millis is the relative timeout time
5428 // abstime will be the absolute timeout time
5429 // TODO: replace compute_abstime() with unpackTime()
5430
5431 static struct timespec* compute_abstime(timespec* abstime, jlong millis) {
5432 if (millis < 0) millis = 0;
5433
5434 jlong seconds = millis / 1000;
5435 millis %= 1000;
5436 if (seconds > 50000000) { // see man cond_timedwait(3T)
5437 seconds = 50000000;
5438 }
5439
5440 if (os::supports_monotonic_clock()) {
5441 struct timespec now;
5442 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now);
5443 assert_status(status == 0, status, "clock_gettime");
5444 abstime->tv_sec = now.tv_sec + seconds;
5445 long nanos = now.tv_nsec + millis * NANOSECS_PER_MILLISEC;
5446 if (nanos >= NANOSECS_PER_SEC) {
5447 abstime->tv_sec += 1;
5448 nanos -= NANOSECS_PER_SEC;
5449 }
5450 abstime->tv_nsec = nanos;
5451 } else {
5452 struct timeval now;
5453 int status = gettimeofday(&now, NULL);
5454 assert(status == 0, "gettimeofday");
5455 abstime->tv_sec = now.tv_sec + seconds;
5456 long usec = now.tv_usec + millis * 1000;
5457 if (usec >= 1000000) {
5458 abstime->tv_sec += 1;
5459 usec -= 1000000;
5460 }
5461 abstime->tv_nsec = usec * 1000;
5462 }
5463 return abstime;
5464 }
5465
5466 void os::PlatformEvent::park() { // AKA "down()"
5467 // Invariant: Only the thread associated with the Event/PlatformEvent
5468 // may call park().
5469 // TODO: assert that _Assoc != NULL or _Assoc == Self
5470 assert(_nParked == 0, "invariant");
5471
5472 int v;
5473 for (;;) {
5474 v = _Event;
5475 if (Atomic::cmpxchg(v-1, &_Event, v) == v) break;
5476 }
5477 guarantee(v >= 0, "invariant");
5478 if (v == 0) {
5479 // Do this the hard way by blocking ...
5480 int status = pthread_mutex_lock(_mutex);
5481 assert_status(status == 0, status, "mutex_lock");
5482 guarantee(_nParked == 0, "invariant");
5483 ++_nParked;
5484 while (_Event < 0) {
5485 status = pthread_cond_wait(_cond, _mutex);
5486 // for some reason, under 2.7 lwp_cond_wait() may return ETIME ...
5487 // Treat this the same as if the wait was interrupted
5488 if (status == ETIME) { status = EINTR; }
5489 assert_status(status == 0 || status == EINTR, status, "cond_wait");
5490 }
5491 --_nParked;
5492
5493 _Event = 0;
5494 status = pthread_mutex_unlock(_mutex);
5495 assert_status(status == 0, status, "mutex_unlock");
5496 // Paranoia to ensure our locked and lock-free paths interact
5497 // correctly with each other.
5498 OrderAccess::fence();
5499 }
5500 guarantee(_Event >= 0, "invariant");
5501 }
5502
5503 int os::PlatformEvent::park(jlong millis) {
5504 guarantee(_nParked == 0, "invariant");
5505
5506 int v;
5507 for (;;) {
5508 v = _Event;
5509 if (Atomic::cmpxchg(v-1, &_Event, v) == v) break;
5510 }
5511 guarantee(v >= 0, "invariant");
5512 if (v != 0) return OS_OK;
5513
5514 // We do this the hard way, by blocking the thread.
5515 // Consider enforcing a minimum timeout value.
5516 struct timespec abst;
5517 compute_abstime(&abst, millis);
5518
5519 int ret = OS_TIMEOUT;
5520 int status = pthread_mutex_lock(_mutex);
5521 assert_status(status == 0, status, "mutex_lock");
5522 guarantee(_nParked == 0, "invariant");
5523 ++_nParked;
5524
5525 // Object.wait(timo) will return because of
5526 // (a) notification
5527 // (b) timeout
5528 // (c) thread.interrupt
5529 //
5530 // Thread.interrupt and object.notify{All} both call Event::set.
5531 // That is, we treat thread.interrupt as a special case of notification.
5532 // We ignore spurious OS wakeups unless FilterSpuriousWakeups is false.
5533 // We assume all ETIME returns are valid.
5534 //
5535 // TODO: properly differentiate simultaneous notify+interrupt.
5536 // In that case, we should propagate the notify to another waiter.
5537
5538 while (_Event < 0) {
5539 status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst);
5540 if (status != 0 && WorkAroundNPTLTimedWaitHang) {
5541 pthread_cond_destroy(_cond);
5542 pthread_cond_init(_cond, os::Linux::condAttr());
5543 }
5544 assert_status(status == 0 || status == EINTR ||
5545 status == ETIME || status == ETIMEDOUT,
5546 status, "cond_timedwait");
5547 if (!FilterSpuriousWakeups) break; // previous semantics
5548 if (status == ETIME || status == ETIMEDOUT) break;
5549 // We consume and ignore EINTR and spurious wakeups.
5550 }
5551 --_nParked;
5552 if (_Event >= 0) {
5553 ret = OS_OK;
5554 }
5555 _Event = 0;
5556 status = pthread_mutex_unlock(_mutex);
5557 assert_status(status == 0, status, "mutex_unlock");
5558 assert(_nParked == 0, "invariant");
5559 // Paranoia to ensure our locked and lock-free paths interact
5560 // correctly with each other.
5561 OrderAccess::fence();
5562 return ret;
5563 }
5564
5565 void os::PlatformEvent::unpark() {
5566 // Transitions for _Event:
5567 // 0 :=> 1
5568 // 1 :=> 1
5569 // -1 :=> either 0 or 1; must signal target thread
5570 // That is, we can safely transition _Event from -1 to either
5571 // 0 or 1.
5572 // See also: "Semaphores in Plan 9" by Mullender & Cox
5573 //
5574 // Note: Forcing a transition from "-1" to "1" on an unpark() means
5575 // that it will take two back-to-back park() calls for the owning
5576 // thread to block. This has the benefit of forcing a spurious return
5577 // from the first park() call after an unpark() call which will help
5578 // shake out uses of park() and unpark() without condition variables.
5579
5580 if (Atomic::xchg(1, &_Event) >= 0) return;
5581
5582 // Wait for the thread associated with the event to vacate
5583 int status = pthread_mutex_lock(_mutex);
5584 assert_status(status == 0, status, "mutex_lock");
5585 int AnyWaiters = _nParked;
5586 assert(AnyWaiters == 0 || AnyWaiters == 1, "invariant");
5587 if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) {
5588 AnyWaiters = 0;
5589 pthread_cond_signal(_cond);
5590 }
5591 status = pthread_mutex_unlock(_mutex);
5592 assert_status(status == 0, status, "mutex_unlock");
5593 if (AnyWaiters != 0) {
5594 status = pthread_cond_signal(_cond);
5595 assert_status(status == 0, status, "cond_signal");
5596 }
5597
5598 // Note that we signal() _after dropping the lock for "immortal" Events.
5599 // This is safe and avoids a common class of futile wakeups. In rare
5600 // circumstances this can cause a thread to return prematurely from
5601 // cond_{timed}wait() but the spurious wakeup is benign and the victim will
5602 // simply re-test the condition and re-park itself.
5603 }
5604
5605
5606 // JSR166
5607 // -------------------------------------------------------
5608
5609 /*
5610 * The solaris and linux implementations of park/unpark are fairly
5611 * conservative for now, but can be improved. They currently use a
5612 * mutex/condvar pair, plus a a count.
5613 * Park decrements count if > 0, else does a condvar wait. Unpark
5614 * sets count to 1 and signals condvar. Only one thread ever waits
5615 * on the condvar. Contention seen when trying to park implies that someone
5616 * is unparking you, so don't wait. And spurious returns are fine, so there
5617 * is no need to track notifications.
5618 */
5619
5620 /*
5621 * This code is common to linux and solaris and will be moved to a
5622 * common place in dolphin.
5623 *
5624 * The passed in time value is either a relative time in nanoseconds
5625 * or an absolute time in milliseconds. Either way it has to be unpacked
5626 * into suitable seconds and nanoseconds components and stored in the
5627 * given timespec structure.
5628 * Given time is a 64-bit value and the time_t used in the timespec is only
5629 * a signed-32-bit value (except on 64-bit Linux) we have to watch for
5630 * overflow if times way in the future are given. Further on Solaris versions
5631 * prior to 10 there is a restriction (see cond_timedwait) that the specified
5632 * number of seconds, in abstime, is less than current_time + 100,000,000.
5633 * As it will be 28 years before "now + 100000000" will overflow we can
5634 * ignore overflow and just impose a hard-limit on seconds using the value
5635 * of "now + 100,000,000". This places a limit on the timeout of about 3.17
5636 * years from "now".
5637 */
5638
5639 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) {
5640 assert(time > 0, "convertTime");
5641 time_t max_secs = 0;
5642
5643 if (!os::supports_monotonic_clock() || isAbsolute) {
5644 struct timeval now;
5645 int status = gettimeofday(&now, NULL);
5646 assert(status == 0, "gettimeofday");
5647
5648 max_secs = now.tv_sec + MAX_SECS;
5649
5650 if (isAbsolute) {
5651 jlong secs = time / 1000;
5652 if (secs > max_secs) {
5653 absTime->tv_sec = max_secs;
5654 } else {
5655 absTime->tv_sec = secs;
5656 }
5657 absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC;
5658 } else {
5659 jlong secs = time / NANOSECS_PER_SEC;
5660 if (secs >= MAX_SECS) {
5661 absTime->tv_sec = max_secs;
5662 absTime->tv_nsec = 0;
5663 } else {
5664 absTime->tv_sec = now.tv_sec + secs;
5665 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000;
5666 if (absTime->tv_nsec >= NANOSECS_PER_SEC) {
5667 absTime->tv_nsec -= NANOSECS_PER_SEC;
5668 ++absTime->tv_sec; // note: this must be <= max_secs
5669 }
5670 }
5671 }
5672 } else {
5673 // must be relative using monotonic clock
5674 struct timespec now;
5675 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now);
5676 assert_status(status == 0, status, "clock_gettime");
5677 max_secs = now.tv_sec + MAX_SECS;
5678 jlong secs = time / NANOSECS_PER_SEC;
5679 if (secs >= MAX_SECS) {
5680 absTime->tv_sec = max_secs;
5681 absTime->tv_nsec = 0;
5682 } else {
5683 absTime->tv_sec = now.tv_sec + secs;
5684 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_nsec;
5685 if (absTime->tv_nsec >= NANOSECS_PER_SEC) {
5686 absTime->tv_nsec -= NANOSECS_PER_SEC;
5687 ++absTime->tv_sec; // note: this must be <= max_secs
5688 }
5689 }
5690 }
5691 assert(absTime->tv_sec >= 0, "tv_sec < 0");
5692 assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs");
5693 assert(absTime->tv_nsec >= 0, "tv_nsec < 0");
5694 assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec");
5695 }
5696
5697 void Parker::park(bool isAbsolute, jlong time) {
5698 // Ideally we'd do something useful while spinning, such
5699 // as calling unpackTime().
5700
5701 // Optional fast-path check:
5702 // Return immediately if a permit is available.
5703 // We depend on Atomic::xchg() having full barrier semantics
5704 // since we are doing a lock-free update to _counter.
5705 if (Atomic::xchg(0, &_counter) > 0) return;
5706
5707 Thread* thread = Thread::current();
5708 assert(thread->is_Java_thread(), "Must be JavaThread");
5709 JavaThread *jt = (JavaThread *)thread;
5710
5711 // Optional optimization -- avoid state transitions if there's an interrupt pending.
5712 // Check interrupt before trying to wait
5713 if (Thread::is_interrupted(thread, false)) {
5714 return;
5715 }
5716
5717 // Next, demultiplex/decode time arguments
5718 timespec absTime;
5719 if (time < 0 || (isAbsolute && time == 0)) { // don't wait at all
5720 return;
5721 }
5722 if (time > 0) {
5723 unpackTime(&absTime, isAbsolute, time);
5724 }
5725
5726
5727 // Enter safepoint region
5728 // Beware of deadlocks such as 6317397.
5729 // The per-thread Parker:: mutex is a classic leaf-lock.
5730 // In particular a thread must never block on the Threads_lock while
5731 // holding the Parker:: mutex. If safepoints are pending both the
5732 // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock.
5733 ThreadBlockInVM tbivm(jt);
5734
5735 // Don't wait if cannot get lock since interference arises from
5736 // unblocking. Also. check interrupt before trying wait
5737 if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) {
5738 return;
5739 }
5740
5741 int status;
5742 if (_counter > 0) { // no wait needed
5743 _counter = 0;
5744 status = pthread_mutex_unlock(_mutex);
5745 assert(status == 0, "invariant");
5746 // Paranoia to ensure our locked and lock-free paths interact
5747 // correctly with each other and Java-level accesses.
5748 OrderAccess::fence();
5749 return;
5750 }
5751
5752 #ifdef ASSERT
5753 // Don't catch signals while blocked; let the running threads have the signals.
5754 // (This allows a debugger to break into the running thread.)
5755 sigset_t oldsigs;
5756 sigset_t* allowdebug_blocked = os::Linux::allowdebug_blocked_signals();
5757 pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs);
5758 #endif
5759
5760 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */);
5761 jt->set_suspend_equivalent();
5762 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
5763
5764 assert(_cur_index == -1, "invariant");
5765 if (time == 0) {
5766 _cur_index = REL_INDEX; // arbitrary choice when not timed
5767 status = pthread_cond_wait(&_cond[_cur_index], _mutex);
5768 } else {
5769 _cur_index = isAbsolute ? ABS_INDEX : REL_INDEX;
5770 status = os::Linux::safe_cond_timedwait(&_cond[_cur_index], _mutex, &absTime);
5771 if (status != 0 && WorkAroundNPTLTimedWaitHang) {
5772 pthread_cond_destroy(&_cond[_cur_index]);
5773 pthread_cond_init(&_cond[_cur_index], isAbsolute ? NULL : os::Linux::condAttr());
5774 }
5775 }
5776 _cur_index = -1;
5777 assert_status(status == 0 || status == EINTR ||
5778 status == ETIME || status == ETIMEDOUT,
5779 status, "cond_timedwait");
5780
5781 #ifdef ASSERT
5782 pthread_sigmask(SIG_SETMASK, &oldsigs, NULL);
5783 #endif
5784
5785 _counter = 0;
5786 status = pthread_mutex_unlock(_mutex);
5787 assert_status(status == 0, status, "invariant");
5788 // Paranoia to ensure our locked and lock-free paths interact
5789 // correctly with each other and Java-level accesses.
5790 OrderAccess::fence();
5791
5792 // If externally suspended while waiting, re-suspend
5793 if (jt->handle_special_suspend_equivalent_condition()) {
5794 jt->java_suspend_self();
5795 }
5796 }
5797
5798 void Parker::unpark() {
5799 int status = pthread_mutex_lock(_mutex);
5800 assert(status == 0, "invariant");
5801 const int s = _counter;
5802 _counter = 1;
5803 if (s < 1) {
5804 // thread might be parked
5805 if (_cur_index != -1) {
5806 // thread is definitely parked
5807 if (WorkAroundNPTLTimedWaitHang) {
5808 status = pthread_cond_signal (&_cond[_cur_index]);
5809 assert(status == 0, "invariant");
5810 status = pthread_mutex_unlock(_mutex);
5811 assert(status == 0, "invariant");
5812 } else {
5813 status = pthread_mutex_unlock(_mutex);
5814 assert(status == 0, "invariant");
5815 status = pthread_cond_signal (&_cond[_cur_index]);
5816 assert(status == 0, "invariant");
5817 }
5818 } else {
5819 pthread_mutex_unlock(_mutex);
5820 assert(status == 0, "invariant");
5821 }
5822 } else {
5823 pthread_mutex_unlock(_mutex);
5824 assert(status == 0, "invariant");
5825 }
5826 }
5827
5828
5829 extern char** environ;
5830
5831 #ifndef __NR_fork
5832 #define __NR_fork IA32_ONLY(2) IA64_ONLY(not defined) AMD64_ONLY(57)
5833 #endif
5834
5835 #ifndef __NR_execve
5836 #define __NR_execve IA32_ONLY(11) IA64_ONLY(1033) AMD64_ONLY(59)
5837 #endif
5838
5839 // Run the specified command in a separate process. Return its exit value,
5840 // or -1 on failure (e.g. can't fork a new process).
5841 // Unlike system(), this function can be called from signal handler. It
5842 // doesn't block SIGINT et al.
5843 int os::fork_and_exec(char* cmd) {
5844 const char * argv[4] = {"sh", "-c", cmd, NULL};
5845
5846 // fork() in LinuxThreads/NPTL is not async-safe. It needs to run
5847 // pthread_atfork handlers and reset pthread library. All we need is a
5848 // separate process to execve. Make a direct syscall to fork process.
5849 // On IA64 there's no fork syscall, we have to use fork() and hope for
5850 // the best...
5851 pid_t pid = NOT_IA64(syscall(__NR_fork);)
5852 IA64_ONLY(fork();)
5853
5854 if (pid < 0) {
5855 // fork failed
5856 return -1;
5857
5858 } else if (pid == 0) {
5859 // child process
5860
5861 // execve() in LinuxThreads will call pthread_kill_other_threads_np()
5862 // first to kill every thread on the thread list. Because this list is
5863 // not reset by fork() (see notes above), execve() will instead kill
5864 // every thread in the parent process. We know this is the only thread
5865 // in the new process, so make a system call directly.
5866 // IA64 should use normal execve() from glibc to match the glibc fork()
5867 // above.
5868 NOT_IA64(syscall(__NR_execve, "/bin/sh", argv, environ);)
5869 IA64_ONLY(execve("/bin/sh", (char* const*)argv, environ);)
5870
5871 // execve failed
5872 _exit(-1);
5873
5874 } else {
5875 // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't
5876 // care about the actual exit code, for now.
5877
5878 int status;
5879
5880 // Wait for the child process to exit. This returns immediately if
5881 // the child has already exited. */
5882 while (waitpid(pid, &status, 0) < 0) {
5883 switch (errno) {
5884 case ECHILD: return 0;
5885 case EINTR: break;
5886 default: return -1;
5887 }
5888 }
5889
5890 if (WIFEXITED(status)) {
5891 // The child exited normally; get its exit code.
5892 return WEXITSTATUS(status);
5893 } else if (WIFSIGNALED(status)) {
5894 // The child exited because of a signal
5895 // The best value to return is 0x80 + signal number,
5896 // because that is what all Unix shells do, and because
5897 // it allows callers to distinguish between process exit and
5898 // process death by signal.
5899 return 0x80 + WTERMSIG(status);
5900 } else {
5901 // Unknown exit code; pass it through
5902 return status;
5903 }
5904 }
5905 }
5906
5907 // is_headless_jre()
5908 //
5909 // Test for the existence of xawt/libmawt.so or libawt_xawt.so
5910 // in order to report if we are running in a headless jre
5911 //
5912 // Since JDK8 xawt/libmawt.so was moved into the same directory
5913 // as libawt.so, and renamed libawt_xawt.so
5914 //
5915 bool os::is_headless_jre() {
5916 struct stat statbuf;
5917 char buf[MAXPATHLEN];
5918 char libmawtpath[MAXPATHLEN];
5919 const char *xawtstr = "/xawt/libmawt.so";
5920 const char *new_xawtstr = "/libawt_xawt.so";
5921 char *p;
5922
5923 // Get path to libjvm.so
5924 os::jvm_path(buf, sizeof(buf));
5925
5926 // Get rid of libjvm.so
5927 p = strrchr(buf, '/');
5928 if (p == NULL) return false;
5929 else *p = '\0';
5930
5931 // Get rid of client or server
5932 p = strrchr(buf, '/');
5933 if (p == NULL) return false;
5934 else *p = '\0';
5935
5936 // check xawt/libmawt.so
5937 strcpy(libmawtpath, buf);
5938 strcat(libmawtpath, xawtstr);
5939 if (::stat(libmawtpath, &statbuf) == 0) return false;
5940
5941 // check libawt_xawt.so
5942 strcpy(libmawtpath, buf);
5943 strcat(libmawtpath, new_xawtstr);
5944 if (::stat(libmawtpath, &statbuf) == 0) return false;
5945
5946 return true;
5947 }
5948
5949 // Get the default path to the core file
5950 // Returns the length of the string
5951 int os::get_core_path(char* buffer, size_t bufferSize) {
5952 const char* p = get_current_directory(buffer, bufferSize);
5953
5954 if (p == NULL) {
5955 assert(p != NULL, "failed to get current directory");
5956 return 0;
5957 }
5958
5959 return strlen(buffer);
5960 }
5961
5962 #ifdef JAVASE_EMBEDDED
5963 //
5964 // A thread to watch the '/dev/mem_notify' device, which will tell us when the OS is running low on memory.
5965 //
5966 MemNotifyThread* MemNotifyThread::_memnotify_thread = NULL;
5967
5968 // ctor
5969 //
5970 MemNotifyThread::MemNotifyThread(int fd): Thread() {
5971 assert(memnotify_thread() == NULL, "we can only allocate one MemNotifyThread");
5972 _fd = fd;
5973
5974 if (os::create_thread(this, os::os_thread)) {
5975 _memnotify_thread = this;
5976 os::set_priority(this, NearMaxPriority);
5977 os::start_thread(this);
5978 }
5979 }
5980
5981 // Where all the work gets done
5982 //
5983 void MemNotifyThread::run() {
5984 assert(this == memnotify_thread(), "expected the singleton MemNotifyThread");
5985
5986 // Set up the select arguments
5987 fd_set rfds;
5988 if (_fd != -1) {
5989 FD_ZERO(&rfds);
5990 FD_SET(_fd, &rfds);
5991 }
5992
5993 // Now wait for the mem_notify device to wake up
5994 while (1) {
5995 // Wait for the mem_notify device to signal us..
5996 int rc = select(_fd+1, _fd != -1 ? &rfds : NULL, NULL, NULL, NULL);
5997 if (rc == -1) {
5998 perror("select!\n");
5999 break;
6000 } else if (rc) {
6001 //ssize_t free_before = os::available_memory();
6002 //tty->print ("Notified: Free: %dK \n",os::available_memory()/1024);
6003
6004 // The kernel is telling us there is not much memory left...
6005 // try to do something about that
6006
6007 // If we are not already in a GC, try one.
6008 if (!Universe::heap()->is_gc_active()) {
6009 Universe::heap()->collect(GCCause::_allocation_failure);
6010
6011 //ssize_t free_after = os::available_memory();
6012 //tty->print ("Post-Notify: Free: %dK\n",free_after/1024);
6013 //tty->print ("GC freed: %dK\n", (free_after - free_before)/1024);
6014 }
6015 // We might want to do something like the following if we find the GC's are not helping...
6016 // Universe::heap()->size_policy()->set_gc_time_limit_exceeded(true);
6017 }
6018 }
6019 }
6020
6021 //
6022 // See if the /dev/mem_notify device exists, and if so, start a thread to monitor it.
6023 //
6024 void MemNotifyThread::start() {
6025 int fd;
6026 fd = open ("/dev/mem_notify", O_RDONLY, 0);
6027 if (fd < 0) {
6028 return;
6029 }
6030
6031 if (memnotify_thread() == NULL) {
6032 new MemNotifyThread(fd);
6033 }
6034 }
6035
6036 #endif // JAVASE_EMBEDDED
6037
6038
6039 /////////////// Unit tests ///////////////
6040
6041 #ifndef PRODUCT
6042
6043 #define test_log(...) \
6044 do {\
6045 if (VerboseInternalVMTests) { \
6046 tty->print_cr(__VA_ARGS__); \
6047 tty->flush(); \
6048 }\
6049 } while (false)
6050
6051 class TestReserveMemorySpecial : AllStatic {
6052 public:
6053 static void small_page_write(void* addr, size_t size) {
6054 size_t page_size = os::vm_page_size();
6055
6056 char* end = (char*)addr + size;
6057 for (char* p = (char*)addr; p < end; p += page_size) {
6058 *p = 1;
6059 }
6060 }
6061
6062 static void test_reserve_memory_special_huge_tlbfs_only(size_t size) {
6063 if (!UseHugeTLBFS) {
6064 return;
6065 }
6066
6067 test_log("test_reserve_memory_special_huge_tlbfs_only(" SIZE_FORMAT ")", size);
6068
6069 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_only(size, NULL, false);
6070
6071 if (addr != NULL) {
6072 small_page_write(addr, size);
6073
6074 os::Linux::release_memory_special_huge_tlbfs(addr, size);
6075 }
6076 }
6077
6078 static void test_reserve_memory_special_huge_tlbfs_only() {
6079 if (!UseHugeTLBFS) {
6080 return;
6081 }
6082
6083 size_t lp = os::large_page_size();
6084
6085 for (size_t size = lp; size <= lp * 10; size += lp) {
6086 test_reserve_memory_special_huge_tlbfs_only(size);
6087 }
6088 }
6089
6090 static void test_reserve_memory_special_huge_tlbfs_mixed(size_t size, size_t alignment) {
6091 if (!UseHugeTLBFS) {
6092 return;
6093 }
6094
6095 test_log("test_reserve_memory_special_huge_tlbfs_mixed(" SIZE_FORMAT ", " SIZE_FORMAT ")",
6096 size, alignment);
6097
6098 assert(size >= os::large_page_size(), "Incorrect input to test");
6099
6100 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, NULL, false);
6101
6102 if (addr != NULL) {
6103 small_page_write(addr, size);
6104
6105 os::Linux::release_memory_special_huge_tlbfs(addr, size);
6106 }
6107 }
6108
6109 static void test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(size_t size) {
6110 size_t lp = os::large_page_size();
6111 size_t ag = os::vm_allocation_granularity();
6112
6113 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) {
6114 test_reserve_memory_special_huge_tlbfs_mixed(size, alignment);
6115 }
6116 }
6117
6118 static void test_reserve_memory_special_huge_tlbfs_mixed() {
6119 size_t lp = os::large_page_size();
6120 size_t ag = os::vm_allocation_granularity();
6121
6122 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp);
6123 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + ag);
6124 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + lp / 2);
6125 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2);
6126 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 + ag);
6127 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 - ag);
6128 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 + lp / 2);
6129 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10);
6130 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10 + lp / 2);
6131 }
6132
6133 static void test_reserve_memory_special_huge_tlbfs() {
6134 if (!UseHugeTLBFS) {
6135 return;
6136 }
6137
6138 test_reserve_memory_special_huge_tlbfs_only();
6139 test_reserve_memory_special_huge_tlbfs_mixed();
6140 }
6141
6142 static void test_reserve_memory_special_shm(size_t size, size_t alignment) {
6143 if (!UseSHM) {
6144 return;
6145 }
6146
6147 test_log("test_reserve_memory_special_shm(" SIZE_FORMAT ", " SIZE_FORMAT ")", size, alignment);
6148
6149 char* addr = os::Linux::reserve_memory_special_shm(size, alignment, NULL, false);
6150
6151 if (addr != NULL) {
6152 assert(is_ptr_aligned(addr, alignment), "Check");
6153 assert(is_ptr_aligned(addr, os::large_page_size()), "Check");
6154
6155 small_page_write(addr, size);
6156
6157 os::Linux::release_memory_special_shm(addr, size);
6158 }
6159 }
6160
6161 static void test_reserve_memory_special_shm() {
6162 size_t lp = os::large_page_size();
6163 size_t ag = os::vm_allocation_granularity();
6164
6165 for (size_t size = ag; size < lp * 3; size += ag) {
6166 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) {
6167 test_reserve_memory_special_shm(size, alignment);
6168 }
6169 }
6170 }
6171
6172 static void test() {
6173 test_reserve_memory_special_huge_tlbfs();
6174 test_reserve_memory_special_shm();
6175 }
6176 };
6177
6178 void TestReserveMemorySpecial_test() {
6179 TestReserveMemorySpecial::test();
6180 }
6181
6182 #endif