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_share_linux.hpp"
40 #include "prims/jniFastGetField.hpp"
41 #include "prims/jvm.h"
42 #include "prims/jvm_misc.hpp"
43 #include "runtime/arguments.hpp"
44 #include "runtime/extendedPC.hpp"
45 #include "runtime/globals.hpp"
46 #include "runtime/interfaceSupport.hpp"
47 #include "runtime/init.hpp"
48 #include "runtime/java.hpp"
49 #include "runtime/javaCalls.hpp"
50 #include "runtime/mutexLocker.hpp"
51 #include "runtime/objectMonitor.hpp"
52 #include "runtime/osThread.hpp"
53 #include "runtime/perfMemory.hpp"
54 #include "runtime/sharedRuntime.hpp"
55 #include "runtime/statSampler.hpp"
56 #include "runtime/stubRoutines.hpp"
57 #include "runtime/thread.inline.hpp"
58 #include "runtime/threadCritical.hpp"
59 #include "runtime/timer.hpp"
60 #include "services/attachListener.hpp"
61 #include "services/memTracker.hpp"
62 #include "services/runtimeService.hpp"
63 #include "utilities/decoder.hpp"
64 #include "utilities/defaultStream.hpp"
65 #include "utilities/events.hpp"
66 #include "utilities/elfFile.hpp"
67 #include "utilities/growableArray.hpp"
68 #include "utilities/vmError.hpp"
69
70 // put OS-includes here
71 # include <sys/types.h>
72 # include <sys/mman.h>
73 # include <sys/stat.h>
74 # include <sys/select.h>
75 # include <pthread.h>
76 # include <signal.h>
77 # include <errno.h>
78 # include <dlfcn.h>
79 # include <stdio.h>
80 # include <unistd.h>
81 # include <sys/resource.h>
82 # include <pthread.h>
83 # include <sys/stat.h>
84 # include <sys/time.h>
85 # include <sys/times.h>
86 # include <sys/utsname.h>
87 # include <sys/socket.h>
88 # include <sys/wait.h>
89 # include <pwd.h>
90 # include <poll.h>
91 # include <semaphore.h>
92 # include <fcntl.h>
93 # include <string.h>
94 # include <syscall.h>
95 # include <sys/sysinfo.h>
96 # include <gnu/libc-version.h>
97 # include <sys/ipc.h>
98 # include <sys/shm.h>
99 # include <link.h>
100 # include <stdint.h>
101 # include <inttypes.h>
102 # include <sys/ioctl.h>
103
104 // if RUSAGE_THREAD for getrusage() has not been defined, do it here. The code calling
105 // getrusage() is prepared to handle the associated failure.
106 #ifndef RUSAGE_THREAD
107 #define RUSAGE_THREAD (1) /* only the calling thread */
108 #endif
109
110 #define MAX_PATH (2 * K)
111
112 #define MAX_SECS 100000000
113
114 // for timer info max values which include all bits
115 #define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF)
116
117 #define LARGEPAGES_BIT (1 << 6)
118 ////////////////////////////////////////////////////////////////////////////////
119 // global variables
120 julong os::Linux::_physical_memory = 0;
121
122 address os::Linux::_initial_thread_stack_bottom = NULL;
123 uintptr_t os::Linux::_initial_thread_stack_size = 0;
124
125 int (*os::Linux::_clock_gettime)(clockid_t, struct timespec *) = NULL;
126 int (*os::Linux::_pthread_getcpuclockid)(pthread_t, clockid_t *) = NULL;
127 Mutex* os::Linux::_createThread_lock = NULL;
128 pthread_t os::Linux::_main_thread;
129 int os::Linux::_page_size = -1;
130 const int os::Linux::_vm_default_page_size = (8 * K);
131 bool os::Linux::_is_floating_stack = false;
132 bool os::Linux::_is_NPTL = false;
133 bool os::Linux::_supports_fast_thread_cpu_time = false;
134 const char * os::Linux::_glibc_version = NULL;
135 const char * os::Linux::_libpthread_version = NULL;
136 pthread_condattr_t os::Linux::_condattr[1];
137
138 static jlong initial_time_count=0;
139
140 static int clock_tics_per_sec = 100;
141
142 // For diagnostics to print a message once. see run_periodic_checks
143 static sigset_t check_signal_done;
144 static bool check_signals = true;
145
146 static pid_t _initial_pid = 0;
147
148 /* Signal number used to suspend/resume a thread */
149
150 /* do not use any signal number less than SIGSEGV, see 4355769 */
151 static int SR_signum = SIGUSR2;
152 sigset_t SR_sigset;
153
154 /* Used to protect dlsym() calls */
155 static pthread_mutex_t dl_mutex;
156
157 // Declarations
158 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time);
159
160 #ifdef JAVASE_EMBEDDED
161 class MemNotifyThread: public Thread {
162 friend class VMStructs;
163 public:
164 virtual void run();
165
166 private:
167 static MemNotifyThread* _memnotify_thread;
168 int _fd;
169
170 public:
171
172 // Constructor
173 MemNotifyThread(int fd);
174
175 // Tester
176 bool is_memnotify_thread() const { return true; }
177
178 // Printing
179 char* name() const { return (char*)"Linux MemNotify Thread"; }
180
181 // Returns the single instance of the MemNotifyThread
182 static MemNotifyThread* memnotify_thread() { return _memnotify_thread; }
183
184 // Create and start the single instance of MemNotifyThread
185 static void start();
186 };
187 #endif // JAVASE_EMBEDDED
188
189 // utility functions
190
191 static int SR_initialize();
192
193 julong os::available_memory() {
194 return Linux::available_memory();
195 }
196
197 julong os::Linux::available_memory() {
198 // values in struct sysinfo are "unsigned long"
199 struct sysinfo si;
200 sysinfo(&si);
201
202 return (julong)si.freeram * si.mem_unit;
203 }
204
205 julong os::physical_memory() {
206 return Linux::physical_memory();
207 }
208
209 ////////////////////////////////////////////////////////////////////////////////
210 // environment support
211
212 bool os::getenv(const char* name, char* buf, int len) {
213 const char* val = ::getenv(name);
214 if (val != NULL && strlen(val) < (size_t)len) {
215 strcpy(buf, val);
216 return true;
217 }
218 if (len > 0) buf[0] = 0; // return a null string
219 return false;
220 }
221
222
223 // Return true if user is running as root.
224
225 bool os::have_special_privileges() {
226 static bool init = false;
227 static bool privileges = false;
228 if (!init) {
229 privileges = (getuid() != geteuid()) || (getgid() != getegid());
230 init = true;
231 }
232 return privileges;
233 }
234
235
236 #ifndef SYS_gettid
237 // i386: 224, ia64: 1105, amd64: 186, sparc 143
238 #ifdef __ia64__
239 #define SYS_gettid 1105
240 #elif __i386__
241 #define SYS_gettid 224
242 #elif __amd64__
243 #define SYS_gettid 186
244 #elif __sparc__
245 #define SYS_gettid 143
246 #else
247 #error define gettid for the arch
248 #endif
249 #endif
250
251 // Cpu architecture string
252 #if defined(ZERO)
253 static char cpu_arch[] = ZERO_LIBARCH;
254 #elif defined(IA64)
255 static char cpu_arch[] = "ia64";
256 #elif defined(IA32)
257 static char cpu_arch[] = "i386";
258 #elif defined(AMD64)
259 static char cpu_arch[] = "amd64";
260 #elif defined(ARM)
261 static char cpu_arch[] = "arm";
262 #elif defined(PPC32)
263 static char cpu_arch[] = "ppc";
264 #elif defined(PPC64)
265 static char cpu_arch[] = "ppc64";
266 #elif defined(SPARC)
267 # ifdef _LP64
268 static char cpu_arch[] = "sparcv9";
269 # else
270 static char cpu_arch[] = "sparc";
271 # endif
272 #else
273 #error Add appropriate cpu_arch setting
274 #endif
275
276
277 // pid_t gettid()
278 //
279 // Returns the kernel thread id of the currently running thread. Kernel
280 // thread id is used to access /proc.
281 //
282 // (Note that getpid() on LinuxThreads returns kernel thread id too; but
283 // on NPTL, it returns the same pid for all threads, as required by POSIX.)
284 //
285 pid_t os::Linux::gettid() {
286 int rslt = syscall(SYS_gettid);
287 if (rslt == -1) {
288 // old kernel, no NPTL support
289 return getpid();
290 } else {
291 return (pid_t)rslt;
292 }
293 }
294
295 // Most versions of linux have a bug where the number of processors are
296 // determined by looking at the /proc file system. In a chroot environment,
297 // the system call returns 1. This causes the VM to act as if it is
298 // a single processor and elide locking (see is_MP() call).
299 static bool unsafe_chroot_detected = false;
300 static const char *unstable_chroot_error = "/proc file system not found.\n"
301 "Java may be unstable running multithreaded in a chroot "
302 "environment on Linux when /proc filesystem is not mounted.";
303
304 void os::Linux::initialize_system_info() {
305 set_processor_count(sysconf(_SC_NPROCESSORS_CONF));
306 if (processor_count() == 1) {
307 pid_t pid = os::Linux::gettid();
308 char fname[32];
309 jio_snprintf(fname, sizeof(fname), "/proc/%d", pid);
310 FILE *fp = fopen(fname, "r");
311 if (fp == NULL) {
312 unsafe_chroot_detected = true;
313 } else {
314 fclose(fp);
315 }
316 }
317 _physical_memory = (julong)sysconf(_SC_PHYS_PAGES) * (julong)sysconf(_SC_PAGESIZE);
318 assert(processor_count() > 0, "linux error");
319 }
320
321 void os::init_system_properties_values() {
322 // The next steps are taken in the product version:
323 //
324 // Obtain the JAVA_HOME value from the location of libjvm.so.
325 // This library should be located at:
326 // <JAVA_HOME>/jre/lib/<arch>/{client|server}/libjvm.so.
327 //
328 // If "/jre/lib/" appears at the right place in the path, then we
329 // assume libjvm.so is installed in a JDK and we use this path.
330 //
331 // Otherwise exit with message: "Could not create the Java virtual machine."
332 //
333 // The following extra steps are taken in the debugging version:
334 //
335 // If "/jre/lib/" does NOT appear at the right place in the path
336 // instead of exit check for $JAVA_HOME environment variable.
337 //
338 // If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>,
339 // then we append a fake suffix "hotspot/libjvm.so" to this path so
340 // it looks like libjvm.so is installed there
341 // <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm.so.
342 //
343 // Otherwise exit.
344 //
345 // Important note: if the location of libjvm.so changes this
346 // code needs to be changed accordingly.
347
348 // See ld(1):
349 // The linker uses the following search paths to locate required
350 // shared libraries:
351 // 1: ...
352 // ...
353 // 7: The default directories, normally /lib and /usr/lib.
354 #if defined(AMD64) || defined(_LP64) && (defined(SPARC) || defined(PPC) || defined(S390))
355 #define DEFAULT_LIBPATH "/usr/lib64:/lib64:/lib:/usr/lib"
356 #else
357 #define DEFAULT_LIBPATH "/lib:/usr/lib"
358 #endif
359
360 // Base path of extensions installed on the system.
361 #define SYS_EXT_DIR "/usr/java/packages"
362 #define EXTENSIONS_DIR "/lib/ext"
363 #define ENDORSED_DIR "/lib/endorsed"
364
365 // Buffer that fits several sprintfs.
366 // Note that the space for the colon and the trailing null are provided
367 // by the nulls included by the sizeof operator.
368 const size_t bufsize =
369 MAX3((size_t)MAXPATHLEN, // For dll_dir & friends.
370 (size_t)MAXPATHLEN + sizeof(EXTENSIONS_DIR) + sizeof(SYS_EXT_DIR) + sizeof(EXTENSIONS_DIR), // extensions dir
371 (size_t)MAXPATHLEN + sizeof(ENDORSED_DIR)); // endorsed dir
372 char *buf = (char *)NEW_C_HEAP_ARRAY(char, bufsize, mtInternal);
373
374 // sysclasspath, java_home, dll_dir
375 {
376 char *pslash;
377 os::jvm_path(buf, bufsize);
378
379 // Found the full path to libjvm.so.
380 // Now cut the path to <java_home>/jre if we can.
381 *(strrchr(buf, '/')) = '\0'; // Get rid of /libjvm.so.
382 pslash = strrchr(buf, '/');
383 if (pslash != NULL) {
384 *pslash = '\0'; // Get rid of /{client|server|hotspot}.
385 }
386 Arguments::set_dll_dir(buf);
387
388 if (pslash != NULL) {
389 pslash = strrchr(buf, '/');
390 if (pslash != NULL) {
391 *pslash = '\0'; // Get rid of /<arch>.
392 pslash = strrchr(buf, '/');
393 if (pslash != NULL) {
394 *pslash = '\0'; // Get rid of /lib.
395 }
396 }
397 }
398 Arguments::set_java_home(buf);
399 set_boot_path('/', ':');
400 }
401
402 // Where to look for native libraries.
403 //
404 // Note: Due to a legacy implementation, most of the library path
405 // is set in the launcher. This was to accomodate linking restrictions
406 // on legacy Linux implementations (which are no longer supported).
407 // Eventually, all the library path setting will be done here.
408 //
409 // However, to prevent the proliferation of improperly built native
410 // libraries, the new path component /usr/java/packages is added here.
411 // Eventually, all the library path setting will be done here.
412 {
413 // Get the user setting of LD_LIBRARY_PATH, and prepended it. It
414 // should always exist (until the legacy problem cited above is
415 // addressed).
416 const char *v = ::getenv("LD_LIBRARY_PATH");
417 const char *v_colon = ":";
418 if (v == NULL) { v = ""; v_colon = ""; }
419 // That's +1 for the colon and +1 for the trailing '\0'.
420 char *ld_library_path = (char *)NEW_C_HEAP_ARRAY(char,
421 strlen(v) + 1 +
422 sizeof(SYS_EXT_DIR) + sizeof("/lib/") + strlen(cpu_arch) + sizeof(DEFAULT_LIBPATH) + 1,
423 mtInternal);
424 sprintf(ld_library_path, "%s%s" SYS_EXT_DIR "/lib/%s:" DEFAULT_LIBPATH, v, v_colon, cpu_arch);
425 Arguments::set_library_path(ld_library_path);
426 FREE_C_HEAP_ARRAY(char, ld_library_path, mtInternal);
427 }
428
429 // Extensions directories.
430 sprintf(buf, "%s" EXTENSIONS_DIR ":" SYS_EXT_DIR EXTENSIONS_DIR, Arguments::get_java_home());
431 Arguments::set_ext_dirs(buf);
432
433 // Endorsed standards default directory.
434 sprintf(buf, "%s" ENDORSED_DIR, Arguments::get_java_home());
435 Arguments::set_endorsed_dirs(buf);
436
437 FREE_C_HEAP_ARRAY(char, buf, mtInternal);
438
439 #undef DEFAULT_LIBPATH
440 #undef SYS_EXT_DIR
441 #undef EXTENSIONS_DIR
442 #undef ENDORSED_DIR
443 }
444
445 ////////////////////////////////////////////////////////////////////////////////
446 // breakpoint support
447
448 void os::breakpoint() {
449 BREAKPOINT;
450 }
451
452 extern "C" void breakpoint() {
453 // use debugger to set breakpoint here
454 }
455
456 ////////////////////////////////////////////////////////////////////////////////
457 // signal support
458
459 debug_only(static bool signal_sets_initialized = false);
460 static sigset_t unblocked_sigs, vm_sigs, allowdebug_blocked_sigs;
461
462 bool os::Linux::is_sig_ignored(int sig) {
463 struct sigaction oact;
464 sigaction(sig, (struct sigaction*)NULL, &oact);
465 void* ohlr = oact.sa_sigaction ? CAST_FROM_FN_PTR(void*, oact.sa_sigaction)
466 : CAST_FROM_FN_PTR(void*, oact.sa_handler);
467 if (ohlr == CAST_FROM_FN_PTR(void*, SIG_IGN))
468 return true;
469 else
470 return false;
471 }
472
473 void os::Linux::signal_sets_init() {
474 // Should also have an assertion stating we are still single-threaded.
475 assert(!signal_sets_initialized, "Already initialized");
476 // Fill in signals that are necessarily unblocked for all threads in
477 // the VM. Currently, we unblock the following signals:
478 // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden
479 // by -Xrs (=ReduceSignalUsage));
480 // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all
481 // other threads. The "ReduceSignalUsage" boolean tells us not to alter
482 // the dispositions or masks wrt these signals.
483 // Programs embedding the VM that want to use the above signals for their
484 // own purposes must, at this time, use the "-Xrs" option to prevent
485 // interference with shutdown hooks and BREAK_SIGNAL thread dumping.
486 // (See bug 4345157, and other related bugs).
487 // In reality, though, unblocking these signals is really a nop, since
488 // these signals are not blocked by default.
489 sigemptyset(&unblocked_sigs);
490 sigemptyset(&allowdebug_blocked_sigs);
491 sigaddset(&unblocked_sigs, SIGILL);
492 sigaddset(&unblocked_sigs, SIGSEGV);
493 sigaddset(&unblocked_sigs, SIGBUS);
494 sigaddset(&unblocked_sigs, SIGFPE);
495 #if defined(PPC64)
496 sigaddset(&unblocked_sigs, SIGTRAP);
497 #endif
498 sigaddset(&unblocked_sigs, SR_signum);
499
500 if (!ReduceSignalUsage) {
501 if (!os::Linux::is_sig_ignored(SHUTDOWN1_SIGNAL)) {
502 sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL);
503 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN1_SIGNAL);
504 }
505 if (!os::Linux::is_sig_ignored(SHUTDOWN2_SIGNAL)) {
506 sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL);
507 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN2_SIGNAL);
508 }
509 if (!os::Linux::is_sig_ignored(SHUTDOWN3_SIGNAL)) {
510 sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL);
511 sigaddset(&allowdebug_blocked_sigs, SHUTDOWN3_SIGNAL);
512 }
513 }
514 // Fill in signals that are blocked by all but the VM thread.
515 sigemptyset(&vm_sigs);
516 if (!ReduceSignalUsage)
517 sigaddset(&vm_sigs, BREAK_SIGNAL);
518 debug_only(signal_sets_initialized = true);
519
520 }
521
522 // These are signals that are unblocked while a thread is running Java.
523 // (For some reason, they get blocked by default.)
524 sigset_t* os::Linux::unblocked_signals() {
525 assert(signal_sets_initialized, "Not initialized");
526 return &unblocked_sigs;
527 }
528
529 // These are the signals that are blocked while a (non-VM) thread is
530 // running Java. Only the VM thread handles these signals.
531 sigset_t* os::Linux::vm_signals() {
532 assert(signal_sets_initialized, "Not initialized");
533 return &vm_sigs;
534 }
535
536 // These are signals that are blocked during cond_wait to allow debugger in
537 sigset_t* os::Linux::allowdebug_blocked_signals() {
538 assert(signal_sets_initialized, "Not initialized");
539 return &allowdebug_blocked_sigs;
540 }
541
542 void os::Linux::hotspot_sigmask(Thread* thread) {
543
544 //Save caller's signal mask before setting VM signal mask
545 sigset_t caller_sigmask;
546 pthread_sigmask(SIG_BLOCK, NULL, &caller_sigmask);
547
548 OSThread* osthread = thread->osthread();
549 osthread->set_caller_sigmask(caller_sigmask);
550
551 pthread_sigmask(SIG_UNBLOCK, os::Linux::unblocked_signals(), NULL);
552
553 if (!ReduceSignalUsage) {
554 if (thread->is_VM_thread()) {
555 // Only the VM thread handles BREAK_SIGNAL ...
556 pthread_sigmask(SIG_UNBLOCK, vm_signals(), NULL);
557 } else {
558 // ... all other threads block BREAK_SIGNAL
559 pthread_sigmask(SIG_BLOCK, vm_signals(), NULL);
560 }
561 }
562 }
563
564 //////////////////////////////////////////////////////////////////////////////
565 // detecting pthread library
566
567 void os::Linux::libpthread_init() {
568 // Save glibc and pthread version strings. Note that _CS_GNU_LIBC_VERSION
569 // and _CS_GNU_LIBPTHREAD_VERSION are supported in glibc >= 2.3.2. Use a
570 // generic name for earlier versions.
571 // Define macros here so we can build HotSpot on old systems.
572 # ifndef _CS_GNU_LIBC_VERSION
573 # define _CS_GNU_LIBC_VERSION 2
574 # endif
575 # ifndef _CS_GNU_LIBPTHREAD_VERSION
576 # define _CS_GNU_LIBPTHREAD_VERSION 3
577 # endif
578
579 size_t n = confstr(_CS_GNU_LIBC_VERSION, NULL, 0);
580 if (n > 0) {
581 char *str = (char *)malloc(n, mtInternal);
582 confstr(_CS_GNU_LIBC_VERSION, str, n);
583 os::Linux::set_glibc_version(str);
584 } else {
585 // _CS_GNU_LIBC_VERSION is not supported, try gnu_get_libc_version()
586 static char _gnu_libc_version[32];
587 jio_snprintf(_gnu_libc_version, sizeof(_gnu_libc_version),
588 "glibc %s %s", gnu_get_libc_version(), gnu_get_libc_release());
589 os::Linux::set_glibc_version(_gnu_libc_version);
590 }
591
592 n = confstr(_CS_GNU_LIBPTHREAD_VERSION, NULL, 0);
593 if (n > 0) {
594 char *str = (char *)malloc(n, mtInternal);
595 confstr(_CS_GNU_LIBPTHREAD_VERSION, str, n);
596 // Vanilla RH-9 (glibc 2.3.2) has a bug that confstr() always tells
597 // us "NPTL-0.29" even we are running with LinuxThreads. Check if this
598 // is the case. LinuxThreads has a hard limit on max number of threads.
599 // So sysconf(_SC_THREAD_THREADS_MAX) will return a positive value.
600 // On the other hand, NPTL does not have such a limit, sysconf()
601 // will return -1 and errno is not changed. Check if it is really NPTL.
602 if (strcmp(os::Linux::glibc_version(), "glibc 2.3.2") == 0 &&
603 strstr(str, "NPTL") &&
604 sysconf(_SC_THREAD_THREADS_MAX) > 0) {
605 free(str);
606 os::Linux::set_libpthread_version("linuxthreads");
607 } else {
608 os::Linux::set_libpthread_version(str);
609 }
610 } else {
611 // glibc before 2.3.2 only has LinuxThreads.
612 os::Linux::set_libpthread_version("linuxthreads");
613 }
614
615 if (strstr(libpthread_version(), "NPTL")) {
616 os::Linux::set_is_NPTL();
617 } else {
618 os::Linux::set_is_LinuxThreads();
619 }
620
621 // LinuxThreads have two flavors: floating-stack mode, which allows variable
622 // stack size; and fixed-stack mode. NPTL is always floating-stack.
623 if (os::Linux::is_NPTL() || os::Linux::supports_variable_stack_size()) {
624 os::Linux::set_is_floating_stack();
625 }
626 }
627
628 /////////////////////////////////////////////////////////////////////////////
629 // thread stack
630
631 // Force Linux kernel to expand current thread stack. If "bottom" is close
632 // to the stack guard, caller should block all signals.
633 //
634 // MAP_GROWSDOWN:
635 // A special mmap() flag that is used to implement thread stacks. It tells
636 // kernel that the memory region should extend downwards when needed. This
637 // allows early versions of LinuxThreads to only mmap the first few pages
638 // when creating a new thread. Linux kernel will automatically expand thread
639 // stack as needed (on page faults).
640 //
641 // However, because the memory region of a MAP_GROWSDOWN stack can grow on
642 // demand, if a page fault happens outside an already mapped MAP_GROWSDOWN
643 // region, it's hard to tell if the fault is due to a legitimate stack
644 // access or because of reading/writing non-exist memory (e.g. buffer
645 // overrun). As a rule, if the fault happens below current stack pointer,
646 // Linux kernel does not expand stack, instead a SIGSEGV is sent to the
647 // application (see Linux kernel fault.c).
648 //
649 // This Linux feature can cause SIGSEGV when VM bangs thread stack for
650 // stack overflow detection.
651 //
652 // Newer version of LinuxThreads (since glibc-2.2, or, RH-7.x) and NPTL do
653 // not use this flag. However, the stack of initial thread is not created
654 // by pthread, it is still MAP_GROWSDOWN. Also it's possible (though
655 // unlikely) that user code can create a thread with MAP_GROWSDOWN stack
656 // and then attach the thread to JVM.
657 //
658 // To get around the problem and allow stack banging on Linux, we need to
659 // manually expand thread stack after receiving the SIGSEGV.
660 //
661 // There are two ways to expand thread stack to address "bottom", we used
662 // both of them in JVM before 1.5:
663 // 1. adjust stack pointer first so that it is below "bottom", and then
664 // touch "bottom"
665 // 2. mmap() the page in question
666 //
667 // Now alternate signal stack is gone, it's harder to use 2. For instance,
668 // if current sp is already near the lower end of page 101, and we need to
669 // call mmap() to map page 100, it is possible that part of the mmap() frame
670 // will be placed in page 100. When page 100 is mapped, it is zero-filled.
671 // That will destroy the mmap() frame and cause VM to crash.
672 //
673 // The following code works by adjusting sp first, then accessing the "bottom"
674 // page to force a page fault. Linux kernel will then automatically expand the
675 // stack mapping.
676 //
677 // _expand_stack_to() assumes its frame size is less than page size, which
678 // should always be true if the function is not inlined.
679
680 #if __GNUC__ < 3 // gcc 2.x does not support noinline attribute
681 #define NOINLINE
682 #else
683 #define NOINLINE __attribute__ ((noinline))
684 #endif
685
686 static void _expand_stack_to(address bottom) NOINLINE;
687
688 static void _expand_stack_to(address bottom) {
689 address sp;
690 size_t size;
691 volatile char *p;
692
693 // Adjust bottom to point to the largest address within the same page, it
694 // gives us a one-page buffer if alloca() allocates slightly more memory.
695 bottom = (address)align_size_down((uintptr_t)bottom, os::Linux::page_size());
696 bottom += os::Linux::page_size() - 1;
697
698 // sp might be slightly above current stack pointer; if that's the case, we
699 // will alloca() a little more space than necessary, which is OK. Don't use
700 // os::current_stack_pointer(), as its result can be slightly below current
701 // stack pointer, causing us to not alloca enough to reach "bottom".
702 sp = (address)&sp;
703
704 if (sp > bottom) {
705 size = sp - bottom;
706 p = (volatile char *)alloca(size);
707 assert(p != NULL && p <= (volatile char *)bottom, "alloca problem?");
708 p[0] = '\0';
709 }
710 }
711
712 bool os::Linux::manually_expand_stack(JavaThread * t, address addr) {
713 assert(t!=NULL, "just checking");
714 assert(t->osthread()->expanding_stack(), "expand should be set");
715 assert(t->stack_base() != NULL, "stack_base was not initialized");
716
717 if (addr < t->stack_base() && addr >= t->stack_yellow_zone_base()) {
718 sigset_t mask_all, old_sigset;
719 sigfillset(&mask_all);
720 pthread_sigmask(SIG_SETMASK, &mask_all, &old_sigset);
721 _expand_stack_to(addr);
722 pthread_sigmask(SIG_SETMASK, &old_sigset, NULL);
723 return true;
724 }
725 return false;
726 }
727
728 //////////////////////////////////////////////////////////////////////////////
729 // create new thread
730
731 static address highest_vm_reserved_address();
732
733 // check if it's safe to start a new thread
734 static bool _thread_safety_check(Thread* thread) {
735 if (os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack()) {
736 // Fixed stack LinuxThreads (SuSE Linux/x86, and some versions of Redhat)
737 // Heap is mmap'ed at lower end of memory space. Thread stacks are
738 // allocated (MAP_FIXED) from high address space. Every thread stack
739 // occupies a fixed size slot (usually 2Mbytes, but user can change
740 // it to other values if they rebuild LinuxThreads).
741 //
742 // Problem with MAP_FIXED is that mmap() can still succeed even part of
743 // the memory region has already been mmap'ed. That means if we have too
744 // many threads and/or very large heap, eventually thread stack will
745 // collide with heap.
746 //
747 // Here we try to prevent heap/stack collision by comparing current
748 // stack bottom with the highest address that has been mmap'ed by JVM
749 // plus a safety margin for memory maps created by native code.
750 //
751 // This feature can be disabled by setting ThreadSafetyMargin to 0
752 //
753 if (ThreadSafetyMargin > 0) {
754 address stack_bottom = os::current_stack_base() - os::current_stack_size();
755
756 // not safe if our stack extends below the safety margin
757 return stack_bottom - ThreadSafetyMargin >= highest_vm_reserved_address();
758 } else {
759 return true;
760 }
761 } else {
762 // Floating stack LinuxThreads or NPTL:
763 // Unlike fixed stack LinuxThreads, thread stacks are not MAP_FIXED. When
764 // there's not enough space left, pthread_create() will fail. If we come
765 // here, that means enough space has been reserved for stack.
766 return true;
767 }
768 }
769
770 // Thread start routine for all newly created threads
771 static void *java_start(Thread *thread) {
772 // Try to randomize the cache line index of hot stack frames.
773 // This helps when threads of the same stack traces evict each other's
774 // cache lines. The threads can be either from the same JVM instance, or
775 // from different JVM instances. The benefit is especially true for
776 // processors with hyperthreading technology.
777 static int counter = 0;
778 int pid = os::current_process_id();
779 alloca(((pid ^ counter++) & 7) * 128);
780
781 ThreadLocalStorage::set_thread(thread);
782
783 OSThread* osthread = thread->osthread();
784 Monitor* sync = osthread->startThread_lock();
785
786 // non floating stack LinuxThreads needs extra check, see above
787 if (!_thread_safety_check(thread)) {
788 // notify parent thread
789 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
790 osthread->set_state(ZOMBIE);
791 sync->notify_all();
792 return NULL;
793 }
794
795 // thread_id is kernel thread id (similar to Solaris LWP id)
796 osthread->set_thread_id(os::Linux::gettid());
797
798 if (UseNUMA) {
799 int lgrp_id = os::numa_get_group_id();
800 if (lgrp_id != -1) {
801 thread->set_lgrp_id(lgrp_id);
802 }
803 }
804 // initialize signal mask for this thread
805 os::Linux::hotspot_sigmask(thread);
806
807 // initialize floating point control register
808 os::Linux::init_thread_fpu_state();
809
810 // handshaking with parent thread
811 {
812 MutexLockerEx ml(sync, Mutex::_no_safepoint_check_flag);
813
814 // notify parent thread
815 osthread->set_state(INITIALIZED);
816 sync->notify_all();
817
818 // wait until os::start_thread()
819 while (osthread->get_state() == INITIALIZED) {
820 sync->wait(Mutex::_no_safepoint_check_flag);
821 }
822 }
823
824 // call one more level start routine
825 thread->run();
826
827 return 0;
828 }
829
830 bool os::create_thread(Thread* thread, ThreadType thr_type, size_t stack_size) {
831 assert(thread->osthread() == NULL, "caller responsible");
832
833 // Allocate the OSThread object
834 OSThread* osthread = new OSThread(NULL, NULL);
835 if (osthread == NULL) {
836 return false;
837 }
838
839 // set the correct thread state
840 osthread->set_thread_type(thr_type);
841
842 // Initial state is ALLOCATED but not INITIALIZED
843 osthread->set_state(ALLOCATED);
844
845 thread->set_osthread(osthread);
846
847 // init thread attributes
848 pthread_attr_t attr;
849 pthread_attr_init(&attr);
850 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
851
852 // stack size
853 if (os::Linux::supports_variable_stack_size()) {
854 // calculate stack size if it's not specified by caller
855 if (stack_size == 0) {
856 stack_size = os::Linux::default_stack_size(thr_type);
857
858 switch (thr_type) {
859 case os::java_thread:
860 // Java threads use ThreadStackSize which default value can be
861 // changed with the flag -Xss
862 assert (JavaThread::stack_size_at_create() > 0, "this should be set");
863 stack_size = JavaThread::stack_size_at_create();
864 break;
865 case os::compiler_thread:
866 if (CompilerThreadStackSize > 0) {
867 stack_size = (size_t)(CompilerThreadStackSize * K);
868 break;
869 } // else fall through:
870 // use VMThreadStackSize if CompilerThreadStackSize is not defined
871 case os::vm_thread:
872 case os::pgc_thread:
873 case os::cgc_thread:
874 case os::watcher_thread:
875 if (VMThreadStackSize > 0) stack_size = (size_t)(VMThreadStackSize * K);
876 break;
877 }
878 }
879
880 stack_size = MAX2(stack_size, os::Linux::min_stack_allowed);
881 pthread_attr_setstacksize(&attr, stack_size);
882 } else {
883 // let pthread_create() pick the default value.
884 }
885
886 // glibc guard page
887 pthread_attr_setguardsize(&attr, os::Linux::default_guard_size(thr_type));
888
889 ThreadState state;
890
891 {
892 // Serialize thread creation if we are running with fixed stack LinuxThreads
893 bool lock = os::Linux::is_LinuxThreads() && !os::Linux::is_floating_stack();
894 if (lock) {
895 os::Linux::createThread_lock()->lock_without_safepoint_check();
896 }
897
898 pthread_t tid;
899 int ret = pthread_create(&tid, &attr, (void* (*)(void*)) java_start, thread);
900
901 pthread_attr_destroy(&attr);
902
903 if (ret != 0) {
904 if (PrintMiscellaneous && (Verbose || WizardMode)) {
905 perror("pthread_create()");
906 }
907 // Need to clean up stuff we've allocated so far
908 thread->set_osthread(NULL);
909 delete osthread;
910 if (lock) os::Linux::createThread_lock()->unlock();
911 return false;
912 }
913
914 // Store pthread info into the OSThread
915 osthread->set_pthread_id(tid);
916
917 // Wait until child thread is either initialized or aborted
918 {
919 Monitor* sync_with_child = osthread->startThread_lock();
920 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
921 while ((state = osthread->get_state()) == ALLOCATED) {
922 sync_with_child->wait(Mutex::_no_safepoint_check_flag);
923 }
924 }
925
926 if (lock) {
927 os::Linux::createThread_lock()->unlock();
928 }
929 }
930
931 // Aborted due to thread limit being reached
932 if (state == ZOMBIE) {
933 thread->set_osthread(NULL);
934 delete osthread;
935 return false;
936 }
937
938 // The thread is returned suspended (in state INITIALIZED),
939 // and is started higher up in the call chain
940 assert(state == INITIALIZED, "race condition");
941 return true;
942 }
943
944 /////////////////////////////////////////////////////////////////////////////
945 // attach existing thread
946
947 // bootstrap the main thread
948 bool os::create_main_thread(JavaThread* thread) {
949 assert(os::Linux::_main_thread == pthread_self(), "should be called inside main thread");
950 return create_attached_thread(thread);
951 }
952
953 bool os::create_attached_thread(JavaThread* thread) {
954 #ifdef ASSERT
955 thread->verify_not_published();
956 #endif
957
958 // Allocate the OSThread object
959 OSThread* osthread = new OSThread(NULL, NULL);
960
961 if (osthread == NULL) {
962 return false;
963 }
964
965 // Store pthread info into the OSThread
966 osthread->set_thread_id(os::Linux::gettid());
967 osthread->set_pthread_id(::pthread_self());
968
969 // initialize floating point control register
970 os::Linux::init_thread_fpu_state();
971
972 // Initial thread state is RUNNABLE
973 osthread->set_state(RUNNABLE);
974
975 thread->set_osthread(osthread);
976
977 if (UseNUMA) {
978 int lgrp_id = os::numa_get_group_id();
979 if (lgrp_id != -1) {
980 thread->set_lgrp_id(lgrp_id);
981 }
982 }
983
984 if (os::Linux::is_initial_thread()) {
985 // If current thread is initial thread, its stack is mapped on demand,
986 // see notes about MAP_GROWSDOWN. Here we try to force kernel to map
987 // the entire stack region to avoid SEGV in stack banging.
988 // It is also useful to get around the heap-stack-gap problem on SuSE
989 // kernel (see 4821821 for details). We first expand stack to the top
990 // of yellow zone, then enable stack yellow zone (order is significant,
991 // enabling yellow zone first will crash JVM on SuSE Linux), so there
992 // is no gap between the last two virtual memory regions.
993
994 JavaThread *jt = (JavaThread *)thread;
995 address addr = jt->stack_yellow_zone_base();
996 assert(addr != NULL, "initialization problem?");
997 assert(jt->stack_available(addr) > 0, "stack guard should not be enabled");
998
999 osthread->set_expanding_stack();
1000 os::Linux::manually_expand_stack(jt, addr);
1001 osthread->clear_expanding_stack();
1002 }
1003
1004 // initialize signal mask for this thread
1005 // and save the caller's signal mask
1006 os::Linux::hotspot_sigmask(thread);
1007
1008 return true;
1009 }
1010
1011 void os::pd_start_thread(Thread* thread) {
1012 OSThread * osthread = thread->osthread();
1013 assert(osthread->get_state() != INITIALIZED, "just checking");
1014 Monitor* sync_with_child = osthread->startThread_lock();
1015 MutexLockerEx ml(sync_with_child, Mutex::_no_safepoint_check_flag);
1016 sync_with_child->notify();
1017 }
1018
1019 // Free Linux resources related to the OSThread
1020 void os::free_thread(OSThread* osthread) {
1021 assert(osthread != NULL, "osthread not set");
1022
1023 if (Thread::current()->osthread() == osthread) {
1024 // Restore caller's signal mask
1025 sigset_t sigmask = osthread->caller_sigmask();
1026 pthread_sigmask(SIG_SETMASK, &sigmask, NULL);
1027 }
1028
1029 delete osthread;
1030 }
1031
1032 //////////////////////////////////////////////////////////////////////////////
1033 // thread local storage
1034
1035 // Restore the thread pointer if the destructor is called. This is in case
1036 // someone from JNI code sets up a destructor with pthread_key_create to run
1037 // detachCurrentThread on thread death. Unless we restore the thread pointer we
1038 // will hang or crash. When detachCurrentThread is called the key will be set
1039 // to null and we will not be called again. If detachCurrentThread is never
1040 // called we could loop forever depending on the pthread implementation.
1041 static void restore_thread_pointer(void* p) {
1042 Thread* thread = (Thread*) p;
1043 os::thread_local_storage_at_put(ThreadLocalStorage::thread_index(), thread);
1044 }
1045
1046 int os::allocate_thread_local_storage() {
1047 pthread_key_t key;
1048 int rslt = pthread_key_create(&key, restore_thread_pointer);
1049 assert(rslt == 0, "cannot allocate thread local storage");
1050 return (int)key;
1051 }
1052
1053 // Note: This is currently not used by VM, as we don't destroy TLS key
1054 // on VM exit.
1055 void os::free_thread_local_storage(int index) {
1056 int rslt = pthread_key_delete((pthread_key_t)index);
1057 assert(rslt == 0, "invalid index");
1058 }
1059
1060 void os::thread_local_storage_at_put(int index, void* value) {
1061 int rslt = pthread_setspecific((pthread_key_t)index, value);
1062 assert(rslt == 0, "pthread_setspecific failed");
1063 }
1064
1065 extern "C" Thread* get_thread() {
1066 return ThreadLocalStorage::thread();
1067 }
1068
1069 //////////////////////////////////////////////////////////////////////////////
1070 // initial thread
1071
1072 // Check if current thread is the initial thread, similar to Solaris thr_main.
1073 bool os::Linux::is_initial_thread(void) {
1074 char dummy;
1075 // If called before init complete, thread stack bottom will be null.
1076 // Can be called if fatal error occurs before initialization.
1077 if (initial_thread_stack_bottom() == NULL) return false;
1078 assert(initial_thread_stack_bottom() != NULL &&
1079 initial_thread_stack_size() != 0,
1080 "os::init did not locate initial thread's stack region");
1081 if ((address)&dummy >= initial_thread_stack_bottom() &&
1082 (address)&dummy < initial_thread_stack_bottom() + initial_thread_stack_size())
1083 return true;
1084 else return false;
1085 }
1086
1087 // Find the virtual memory area that contains addr
1088 static bool find_vma(address addr, address* vma_low, address* vma_high) {
1089 FILE *fp = fopen("/proc/self/maps", "r");
1090 if (fp) {
1091 address low, high;
1092 while (!feof(fp)) {
1093 if (fscanf(fp, "%p-%p", &low, &high) == 2) {
1094 if (low <= addr && addr < high) {
1095 if (vma_low) *vma_low = low;
1096 if (vma_high) *vma_high = high;
1097 fclose (fp);
1098 return true;
1099 }
1100 }
1101 for (;;) {
1102 int ch = fgetc(fp);
1103 if (ch == EOF || ch == (int)'\n') break;
1104 }
1105 }
1106 fclose(fp);
1107 }
1108 return false;
1109 }
1110
1111 // Locate initial thread stack. This special handling of initial thread stack
1112 // is needed because pthread_getattr_np() on most (all?) Linux distros returns
1113 // bogus value for initial thread.
1114 void os::Linux::capture_initial_stack(size_t max_size) {
1115 // stack size is the easy part, get it from RLIMIT_STACK
1116 size_t stack_size;
1117 struct rlimit rlim;
1118 getrlimit(RLIMIT_STACK, &rlim);
1119 stack_size = rlim.rlim_cur;
1120
1121 // 6308388: a bug in ld.so will relocate its own .data section to the
1122 // lower end of primordial stack; reduce ulimit -s value a little bit
1123 // so we won't install guard page on ld.so's data section.
1124 stack_size -= 2 * page_size();
1125
1126 // 4441425: avoid crash with "unlimited" stack size on SuSE 7.1 or Redhat
1127 // 7.1, in both cases we will get 2G in return value.
1128 // 4466587: glibc 2.2.x compiled w/o "--enable-kernel=2.4.0" (RH 7.0,
1129 // SuSE 7.2, Debian) can not handle alternate signal stack correctly
1130 // for initial thread if its stack size exceeds 6M. Cap it at 2M,
1131 // in case other parts in glibc still assumes 2M max stack size.
1132 // FIXME: alt signal stack is gone, maybe we can relax this constraint?
1133 // Problem still exists RH7.2 (IA64 anyway) but 2MB is a little small
1134 if (stack_size > 2 * K * K IA64_ONLY(*2))
1135 stack_size = 2 * K * K IA64_ONLY(*2);
1136 // Try to figure out where the stack base (top) is. This is harder.
1137 //
1138 // When an application is started, glibc saves the initial stack pointer in
1139 // a global variable "__libc_stack_end", which is then used by system
1140 // libraries. __libc_stack_end should be pretty close to stack top. The
1141 // variable is available since the very early days. However, because it is
1142 // a private interface, it could disappear in the future.
1143 //
1144 // Linux kernel saves start_stack information in /proc/<pid>/stat. Similar
1145 // to __libc_stack_end, it is very close to stack top, but isn't the real
1146 // stack top. Note that /proc may not exist if VM is running as a chroot
1147 // program, so reading /proc/<pid>/stat could fail. Also the contents of
1148 // /proc/<pid>/stat could change in the future (though unlikely).
1149 //
1150 // We try __libc_stack_end first. If that doesn't work, look for
1151 // /proc/<pid>/stat. If neither of them works, we use current stack pointer
1152 // as a hint, which should work well in most cases.
1153
1154 uintptr_t stack_start;
1155
1156 // try __libc_stack_end first
1157 uintptr_t *p = (uintptr_t *)dlsym(RTLD_DEFAULT, "__libc_stack_end");
1158 if (p && *p) {
1159 stack_start = *p;
1160 } else {
1161 // see if we can get the start_stack field from /proc/self/stat
1162 FILE *fp;
1163 int pid;
1164 char state;
1165 int ppid;
1166 int pgrp;
1167 int session;
1168 int nr;
1169 int tpgrp;
1170 unsigned long flags;
1171 unsigned long minflt;
1172 unsigned long cminflt;
1173 unsigned long majflt;
1174 unsigned long cmajflt;
1175 unsigned long utime;
1176 unsigned long stime;
1177 long cutime;
1178 long cstime;
1179 long prio;
1180 long nice;
1181 long junk;
1182 long it_real;
1183 uintptr_t start;
1184 uintptr_t vsize;
1185 intptr_t rss;
1186 uintptr_t rsslim;
1187 uintptr_t scodes;
1188 uintptr_t ecode;
1189 int i;
1190
1191 // Figure what the primordial thread stack base is. Code is inspired
1192 // by email from Hans Boehm. /proc/self/stat begins with current pid,
1193 // followed by command name surrounded by parentheses, state, etc.
1194 char stat[2048];
1195 int statlen;
1196
1197 fp = fopen("/proc/self/stat", "r");
1198 if (fp) {
1199 statlen = fread(stat, 1, 2047, fp);
1200 stat[statlen] = '\0';
1201 fclose(fp);
1202
1203 // Skip pid and the command string. Note that we could be dealing with
1204 // weird command names, e.g. user could decide to rename java launcher
1205 // to "java 1.4.2 :)", then the stat file would look like
1206 // 1234 (java 1.4.2 :)) R ... ...
1207 // We don't really need to know the command string, just find the last
1208 // occurrence of ")" and then start parsing from there. See bug 4726580.
1209 char * s = strrchr(stat, ')');
1210
1211 i = 0;
1212 if (s) {
1213 // Skip blank chars
1214 do s++; while (isspace(*s));
1215
1216 #define _UFM UINTX_FORMAT
1217 #define _DFM INTX_FORMAT
1218
1219 /* 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 */
1220 /* 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 */
1221 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,
1222 &state, /* 3 %c */
1223 &ppid, /* 4 %d */
1224 &pgrp, /* 5 %d */
1225 &session, /* 6 %d */
1226 &nr, /* 7 %d */
1227 &tpgrp, /* 8 %d */
1228 &flags, /* 9 %lu */
1229 &minflt, /* 10 %lu */
1230 &cminflt, /* 11 %lu */
1231 &majflt, /* 12 %lu */
1232 &cmajflt, /* 13 %lu */
1233 &utime, /* 14 %lu */
1234 &stime, /* 15 %lu */
1235 &cutime, /* 16 %ld */
1236 &cstime, /* 17 %ld */
1237 &prio, /* 18 %ld */
1238 &nice, /* 19 %ld */
1239 &junk, /* 20 %ld */
1240 &it_real, /* 21 %ld */
1241 &start, /* 22 UINTX_FORMAT */
1242 &vsize, /* 23 UINTX_FORMAT */
1243 &rss, /* 24 INTX_FORMAT */
1244 &rsslim, /* 25 UINTX_FORMAT */
1245 &scodes, /* 26 UINTX_FORMAT */
1246 &ecode, /* 27 UINTX_FORMAT */
1247 &stack_start); /* 28 UINTX_FORMAT */
1248 }
1249
1250 #undef _UFM
1251 #undef _DFM
1252
1253 if (i != 28 - 2) {
1254 assert(false, "Bad conversion from /proc/self/stat");
1255 // product mode - assume we are the initial thread, good luck in the
1256 // embedded case.
1257 warning("Can't detect initial thread stack location - bad conversion");
1258 stack_start = (uintptr_t) &rlim;
1259 }
1260 } else {
1261 // For some reason we can't open /proc/self/stat (for example, running on
1262 // FreeBSD with a Linux emulator, or inside chroot), this should work for
1263 // most cases, so don't abort:
1264 warning("Can't detect initial thread stack location - no /proc/self/stat");
1265 stack_start = (uintptr_t) &rlim;
1266 }
1267 }
1268
1269 // Now we have a pointer (stack_start) very close to the stack top, the
1270 // next thing to do is to figure out the exact location of stack top. We
1271 // can find out the virtual memory area that contains stack_start by
1272 // reading /proc/self/maps, it should be the last vma in /proc/self/maps,
1273 // and its upper limit is the real stack top. (again, this would fail if
1274 // running inside chroot, because /proc may not exist.)
1275
1276 uintptr_t stack_top;
1277 address low, high;
1278 if (find_vma((address)stack_start, &low, &high)) {
1279 // success, "high" is the true stack top. (ignore "low", because initial
1280 // thread stack grows on demand, its real bottom is high - RLIMIT_STACK.)
1281 stack_top = (uintptr_t)high;
1282 } else {
1283 // failed, likely because /proc/self/maps does not exist
1284 warning("Can't detect initial thread stack location - find_vma failed");
1285 // best effort: stack_start is normally within a few pages below the real
1286 // stack top, use it as stack top, and reduce stack size so we won't put
1287 // guard page outside stack.
1288 stack_top = stack_start;
1289 stack_size -= 16 * page_size();
1290 }
1291
1292 // stack_top could be partially down the page so align it
1293 stack_top = align_size_up(stack_top, page_size());
1294
1295 if (max_size && stack_size > max_size) {
1296 _initial_thread_stack_size = max_size;
1297 } else {
1298 _initial_thread_stack_size = stack_size;
1299 }
1300
1301 _initial_thread_stack_size = align_size_down(_initial_thread_stack_size, page_size());
1302 _initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size;
1303 }
1304
1305 ////////////////////////////////////////////////////////////////////////////////
1306 // time support
1307
1308 // Time since start-up in seconds to a fine granularity.
1309 // Used by VMSelfDestructTimer and the MemProfiler.
1310 double os::elapsedTime() {
1311
1312 return ((double)os::elapsed_counter()) / os::elapsed_frequency(); // nanosecond resolution
1313 }
1314
1315 jlong os::elapsed_counter() {
1316 return javaTimeNanos() - initial_time_count;
1317 }
1318
1319 jlong os::elapsed_frequency() {
1320 return NANOSECS_PER_SEC; // nanosecond resolution
1321 }
1322
1323 bool os::supports_vtime() { return true; }
1324 bool os::enable_vtime() { return false; }
1325 bool os::vtime_enabled() { return false; }
1326
1327 double os::elapsedVTime() {
1328 struct rusage usage;
1329 int retval = getrusage(RUSAGE_THREAD, &usage);
1330 if (retval == 0) {
1331 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);
1332 } else {
1333 // better than nothing, but not much
1334 return elapsedTime();
1335 }
1336 }
1337
1338 jlong os::javaTimeMillis() {
1339 timeval time;
1340 int status = gettimeofday(&time, NULL);
1341 assert(status != -1, "linux error");
1342 return jlong(time.tv_sec) * 1000 + jlong(time.tv_usec / 1000);
1343 }
1344
1345 #ifndef CLOCK_MONOTONIC
1346 #define CLOCK_MONOTONIC (1)
1347 #endif
1348
1349 void os::Linux::clock_init() {
1350 // we do dlopen's in this particular order due to bug in linux
1351 // dynamical loader (see 6348968) leading to crash on exit
1352 void* handle = dlopen("librt.so.1", RTLD_LAZY);
1353 if (handle == NULL) {
1354 handle = dlopen("librt.so", RTLD_LAZY);
1355 }
1356
1357 if (handle) {
1358 int (*clock_getres_func)(clockid_t, struct timespec*) =
1359 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_getres");
1360 int (*clock_gettime_func)(clockid_t, struct timespec*) =
1361 (int(*)(clockid_t, struct timespec*))dlsym(handle, "clock_gettime");
1362 if (clock_getres_func && clock_gettime_func) {
1363 // See if monotonic clock is supported by the kernel. Note that some
1364 // early implementations simply return kernel jiffies (updated every
1365 // 1/100 or 1/1000 second). It would be bad to use such a low res clock
1366 // for nano time (though the monotonic property is still nice to have).
1367 // It's fixed in newer kernels, however clock_getres() still returns
1368 // 1/HZ. We check if clock_getres() works, but will ignore its reported
1369 // resolution for now. Hopefully as people move to new kernels, this
1370 // won't be a problem.
1371 struct timespec res;
1372 struct timespec tp;
1373 if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 &&
1374 clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) {
1375 // yes, monotonic clock is supported
1376 _clock_gettime = clock_gettime_func;
1377 return;
1378 } else {
1379 // close librt if there is no monotonic clock
1380 dlclose(handle);
1381 }
1382 }
1383 }
1384 warning("No monotonic clock was available - timed services may " \
1385 "be adversely affected if the time-of-day clock changes");
1386 }
1387
1388 #ifndef SYS_clock_getres
1389
1390 #if defined(IA32) || defined(AMD64)
1391 #define SYS_clock_getres IA32_ONLY(266) AMD64_ONLY(229)
1392 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y)
1393 #else
1394 #warning "SYS_clock_getres not defined for this platform, disabling fast_thread_cpu_time"
1395 #define sys_clock_getres(x,y) -1
1396 #endif
1397
1398 #else
1399 #define sys_clock_getres(x,y) ::syscall(SYS_clock_getres, x, y)
1400 #endif
1401
1402 void os::Linux::fast_thread_clock_init() {
1403 if (!UseLinuxPosixThreadCPUClocks) {
1404 return;
1405 }
1406 clockid_t clockid;
1407 struct timespec tp;
1408 int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) =
1409 (int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid");
1410
1411 // Switch to using fast clocks for thread cpu time if
1412 // the sys_clock_getres() returns 0 error code.
1413 // Note, that some kernels may support the current thread
1414 // clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks
1415 // returned by the pthread_getcpuclockid().
1416 // If the fast Posix clocks are supported then the sys_clock_getres()
1417 // must return at least tp.tv_sec == 0 which means a resolution
1418 // better than 1 sec. This is extra check for reliability.
1419
1420 if(pthread_getcpuclockid_func &&
1421 pthread_getcpuclockid_func(_main_thread, &clockid) == 0 &&
1422 sys_clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) {
1423
1424 _supports_fast_thread_cpu_time = true;
1425 _pthread_getcpuclockid = pthread_getcpuclockid_func;
1426 }
1427 }
1428
1429 jlong os::javaTimeNanos() {
1430 if (os::supports_monotonic_clock()) {
1431 struct timespec tp;
1432 int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp);
1433 assert(status == 0, "gettime error");
1434 jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec);
1435 return result;
1436 } else {
1437 timeval time;
1438 int status = gettimeofday(&time, NULL);
1439 assert(status != -1, "linux error");
1440 jlong usecs = jlong(time.tv_sec) * (1000 * 1000) + jlong(time.tv_usec);
1441 return 1000 * usecs;
1442 }
1443 }
1444
1445 void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) {
1446 if (os::supports_monotonic_clock()) {
1447 info_ptr->max_value = ALL_64_BITS;
1448
1449 // CLOCK_MONOTONIC - amount of time since some arbitrary point in the past
1450 info_ptr->may_skip_backward = false; // not subject to resetting or drifting
1451 info_ptr->may_skip_forward = false; // not subject to resetting or drifting
1452 } else {
1453 // gettimeofday - based on time in seconds since the Epoch thus does not wrap
1454 info_ptr->max_value = ALL_64_BITS;
1455
1456 // gettimeofday is a real time clock so it skips
1457 info_ptr->may_skip_backward = true;
1458 info_ptr->may_skip_forward = true;
1459 }
1460
1461 info_ptr->kind = JVMTI_TIMER_ELAPSED; // elapsed not CPU time
1462 }
1463
1464 // Return the real, user, and system times in seconds from an
1465 // arbitrary fixed point in the past.
1466 bool os::getTimesSecs(double* process_real_time,
1467 double* process_user_time,
1468 double* process_system_time) {
1469 struct tms ticks;
1470 clock_t real_ticks = times(&ticks);
1471
1472 if (real_ticks == (clock_t) (-1)) {
1473 return false;
1474 } else {
1475 double ticks_per_second = (double) clock_tics_per_sec;
1476 *process_user_time = ((double) ticks.tms_utime) / ticks_per_second;
1477 *process_system_time = ((double) ticks.tms_stime) / ticks_per_second;
1478 *process_real_time = ((double) real_ticks) / ticks_per_second;
1479
1480 return true;
1481 }
1482 }
1483
1484
1485 char * os::local_time_string(char *buf, size_t buflen) {
1486 struct tm t;
1487 time_t long_time;
1488 time(&long_time);
1489 localtime_r(&long_time, &t);
1490 jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d",
1491 t.tm_year + 1900, t.tm_mon + 1, t.tm_mday,
1492 t.tm_hour, t.tm_min, t.tm_sec);
1493 return buf;
1494 }
1495
1496 struct tm* os::localtime_pd(const time_t* clock, struct tm* res) {
1497 return localtime_r(clock, res);
1498 }
1499
1500 ////////////////////////////////////////////////////////////////////////////////
1501 // runtime exit support
1502
1503 // Note: os::shutdown() might be called very early during initialization, or
1504 // called from signal handler. Before adding something to os::shutdown(), make
1505 // sure it is async-safe and can handle partially initialized VM.
1506 void os::shutdown() {
1507
1508 // allow PerfMemory to attempt cleanup of any persistent resources
1509 perfMemory_exit();
1510
1511 // needs to remove object in file system
1512 AttachListener::abort();
1513
1514 // flush buffered output, finish log files
1515 ostream_abort();
1516
1517 // Check for abort hook
1518 abort_hook_t abort_hook = Arguments::abort_hook();
1519 if (abort_hook != NULL) {
1520 abort_hook();
1521 }
1522
1523 }
1524
1525 // Note: os::abort() might be called very early during initialization, or
1526 // called from signal handler. Before adding something to os::abort(), make
1527 // sure it is async-safe and can handle partially initialized VM.
1528 void os::abort(bool dump_core) {
1529 os::shutdown();
1530 if (dump_core) {
1531 #ifndef PRODUCT
1532 fdStream out(defaultStream::output_fd());
1533 out.print_raw("Current thread is ");
1534 char buf[16];
1535 jio_snprintf(buf, sizeof(buf), UINTX_FORMAT, os::current_thread_id());
1536 out.print_raw_cr(buf);
1537 out.print_raw_cr("Dumping core ...");
1538 #endif
1539 ::abort(); // dump core
1540 }
1541
1542 ::exit(1);
1543 }
1544
1545 // Die immediately, no exit hook, no abort hook, no cleanup.
1546 void os::die() {
1547 // _exit() on LinuxThreads only kills current thread
1548 ::abort();
1549 }
1550
1551 // unused on linux for now.
1552 void os::set_error_file(const char *logfile) {}
1553
1554
1555 // This method is a copy of JDK's sysGetLastErrorString
1556 // from src/solaris/hpi/src/system_md.c
1557
1558 size_t os::lasterror(char *buf, size_t len) {
1559
1560 if (errno == 0) return 0;
1561
1562 const char *s = ::strerror(errno);
1563 size_t n = ::strlen(s);
1564 if (n >= len) {
1565 n = len - 1;
1566 }
1567 ::strncpy(buf, s, n);
1568 buf[n] = '\0';
1569 return n;
1570 }
1571
1572 intx os::current_thread_id() { return (intx)pthread_self(); }
1573 int os::current_process_id() {
1574
1575 // Under the old linux thread library, linux gives each thread
1576 // its own process id. Because of this each thread will return
1577 // a different pid if this method were to return the result
1578 // of getpid(2). Linux provides no api that returns the pid
1579 // of the launcher thread for the vm. This implementation
1580 // returns a unique pid, the pid of the launcher thread
1581 // that starts the vm 'process'.
1582
1583 // Under the NPTL, getpid() returns the same pid as the
1584 // launcher thread rather than a unique pid per thread.
1585 // Use gettid() if you want the old pre NPTL behaviour.
1586
1587 // if you are looking for the result of a call to getpid() that
1588 // returns a unique pid for the calling thread, then look at the
1589 // OSThread::thread_id() method in osThread_linux.hpp file
1590
1591 return (int)(_initial_pid ? _initial_pid : getpid());
1592 }
1593
1594 // DLL functions
1595
1596 const char* os::dll_file_extension() { return ".so"; }
1597
1598 // This must be hard coded because it's the system's temporary
1599 // directory not the java application's temp directory, ala java.io.tmpdir.
1600 const char* os::get_temp_directory() { return "/tmp"; }
1601
1602 static bool file_exists(const char* filename) {
1603 struct stat statbuf;
1604 if (filename == NULL || strlen(filename) == 0) {
1605 return false;
1606 }
1607 return os::stat(filename, &statbuf) == 0;
1608 }
1609
1610 bool os::dll_build_name(char* buffer, size_t buflen,
1611 const char* pname, const char* fname) {
1612 bool retval = false;
1613 // Copied from libhpi
1614 const size_t pnamelen = pname ? strlen(pname) : 0;
1615
1616 // Return error on buffer overflow.
1617 if (pnamelen + strlen(fname) + 10 > (size_t) buflen) {
1618 return retval;
1619 }
1620
1621 if (pnamelen == 0) {
1622 snprintf(buffer, buflen, "lib%s.so", fname);
1623 retval = true;
1624 } else if (strchr(pname, *os::path_separator()) != NULL) {
1625 int n;
1626 char** pelements = split_path(pname, &n);
1627 if (pelements == NULL) {
1628 return false;
1629 }
1630 for (int i = 0 ; i < n ; i++) {
1631 // Really shouldn't be NULL, but check can't hurt
1632 if (pelements[i] == NULL || strlen(pelements[i]) == 0) {
1633 continue; // skip the empty path values
1634 }
1635 snprintf(buffer, buflen, "%s/lib%s.so", pelements[i], fname);
1636 if (file_exists(buffer)) {
1637 retval = true;
1638 break;
1639 }
1640 }
1641 // release the storage
1642 for (int i = 0 ; i < n ; i++) {
1643 if (pelements[i] != NULL) {
1644 FREE_C_HEAP_ARRAY(char, pelements[i], mtInternal);
1645 }
1646 }
1647 if (pelements != NULL) {
1648 FREE_C_HEAP_ARRAY(char*, pelements, mtInternal);
1649 }
1650 } else {
1651 snprintf(buffer, buflen, "%s/lib%s.so", pname, fname);
1652 retval = true;
1653 }
1654 return retval;
1655 }
1656
1657 // check if addr is inside libjvm.so
1658 bool os::address_is_in_vm(address addr) {
1659 static address libjvm_base_addr;
1660 Dl_info dlinfo;
1661
1662 if (libjvm_base_addr == NULL) {
1663 if (dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo) != 0) {
1664 libjvm_base_addr = (address)dlinfo.dli_fbase;
1665 }
1666 assert(libjvm_base_addr !=NULL, "Cannot obtain base address for libjvm");
1667 }
1668
1669 if (dladdr((void *)addr, &dlinfo) != 0) {
1670 if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true;
1671 }
1672
1673 return false;
1674 }
1675
1676 bool os::dll_address_to_function_name(address addr, char *buf,
1677 int buflen, int *offset) {
1678 // buf is not optional, but offset is optional
1679 assert(buf != NULL, "sanity check");
1680
1681 Dl_info dlinfo;
1682
1683 if (dladdr((void*)addr, &dlinfo) != 0) {
1684 // see if we have a matching symbol
1685 if (dlinfo.dli_saddr != NULL && dlinfo.dli_sname != NULL) {
1686 if (!Decoder::demangle(dlinfo.dli_sname, buf, buflen)) {
1687 jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname);
1688 }
1689 if (offset != NULL) *offset = addr - (address)dlinfo.dli_saddr;
1690 return true;
1691 }
1692 // no matching symbol so try for just file info
1693 if (dlinfo.dli_fname != NULL && dlinfo.dli_fbase != NULL) {
1694 if (Decoder::decode((address)(addr - (address)dlinfo.dli_fbase),
1695 buf, buflen, offset, dlinfo.dli_fname)) {
1696 return true;
1697 }
1698 }
1699 }
1700
1701 buf[0] = '\0';
1702 if (offset != NULL) *offset = -1;
1703 return false;
1704 }
1705
1706 struct _address_to_library_name {
1707 address addr; // input : memory address
1708 size_t buflen; // size of fname
1709 char* fname; // output: library name
1710 address base; // library base addr
1711 };
1712
1713 static int address_to_library_name_callback(struct dl_phdr_info *info,
1714 size_t size, void *data) {
1715 int i;
1716 bool found = false;
1717 address libbase = NULL;
1718 struct _address_to_library_name * d = (struct _address_to_library_name *)data;
1719
1720 // iterate through all loadable segments
1721 for (i = 0; i < info->dlpi_phnum; i++) {
1722 address segbase = (address)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr);
1723 if (info->dlpi_phdr[i].p_type == PT_LOAD) {
1724 // base address of a library is the lowest address of its loaded
1725 // segments.
1726 if (libbase == NULL || libbase > segbase) {
1727 libbase = segbase;
1728 }
1729 // see if 'addr' is within current segment
1730 if (segbase <= d->addr &&
1731 d->addr < segbase + info->dlpi_phdr[i].p_memsz) {
1732 found = true;
1733 }
1734 }
1735 }
1736
1737 // dlpi_name is NULL or empty if the ELF file is executable, return 0
1738 // so dll_address_to_library_name() can fall through to use dladdr() which
1739 // can figure out executable name from argv[0].
1740 if (found && info->dlpi_name && info->dlpi_name[0]) {
1741 d->base = libbase;
1742 if (d->fname) {
1743 jio_snprintf(d->fname, d->buflen, "%s", info->dlpi_name);
1744 }
1745 return 1;
1746 }
1747 return 0;
1748 }
1749
1750 bool os::dll_address_to_library_name(address addr, char* buf,
1751 int buflen, int* offset) {
1752 // buf is not optional, but offset is optional
1753 assert(buf != NULL, "sanity check");
1754
1755 Dl_info dlinfo;
1756 struct _address_to_library_name data;
1757
1758 // There is a bug in old glibc dladdr() implementation that it could resolve
1759 // to wrong library name if the .so file has a base address != NULL. Here
1760 // we iterate through the program headers of all loaded libraries to find
1761 // out which library 'addr' really belongs to. This workaround can be
1762 // removed once the minimum requirement for glibc is moved to 2.3.x.
1763 data.addr = addr;
1764 data.fname = buf;
1765 data.buflen = buflen;
1766 data.base = NULL;
1767 int rslt = dl_iterate_phdr(address_to_library_name_callback, (void *)&data);
1768
1769 if (rslt) {
1770 // buf already contains library name
1771 if (offset) *offset = addr - data.base;
1772 return true;
1773 }
1774 if (dladdr((void*)addr, &dlinfo) != 0) {
1775 if (dlinfo.dli_fname != NULL) {
1776 jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname);
1777 }
1778 if (dlinfo.dli_fbase != NULL && offset != NULL) {
1779 *offset = addr - (address)dlinfo.dli_fbase;
1780 }
1781 return true;
1782 }
1783
1784 buf[0] = '\0';
1785 if (offset) *offset = -1;
1786 return false;
1787 }
1788
1789 // Loads .dll/.so and
1790 // in case of error it checks if .dll/.so was built for the
1791 // same architecture as Hotspot is running on
1792
1793
1794 // Remember the stack's state. The Linux dynamic linker will change
1795 // the stack to 'executable' at most once, so we must safepoint only once.
1796 bool os::Linux::_stack_is_executable = false;
1797
1798 // VM operation that loads a library. This is necessary if stack protection
1799 // of the Java stacks can be lost during loading the library. If we
1800 // do not stop the Java threads, they can stack overflow before the stacks
1801 // are protected again.
1802 class VM_LinuxDllLoad: public VM_Operation {
1803 private:
1804 const char *_filename;
1805 char *_ebuf;
1806 int _ebuflen;
1807 void *_lib;
1808 public:
1809 VM_LinuxDllLoad(const char *fn, char *ebuf, int ebuflen) :
1810 _filename(fn), _ebuf(ebuf), _ebuflen(ebuflen), _lib(NULL) {}
1811 VMOp_Type type() const { return VMOp_LinuxDllLoad; }
1812 void doit() {
1813 _lib = os::Linux::dll_load_in_vmthread(_filename, _ebuf, _ebuflen);
1814 os::Linux::_stack_is_executable = true;
1815 }
1816 void* loaded_library() { return _lib; }
1817 };
1818
1819 void * os::dll_load(const char *filename, char *ebuf, int ebuflen)
1820 {
1821 void * result = NULL;
1822 bool load_attempted = false;
1823
1824 // Check whether the library to load might change execution rights
1825 // of the stack. If they are changed, the protection of the stack
1826 // guard pages will be lost. We need a safepoint to fix this.
1827 //
1828 // See Linux man page execstack(8) for more info.
1829 if (os::uses_stack_guard_pages() && !os::Linux::_stack_is_executable) {
1830 ElfFile ef(filename);
1831 if (!ef.specifies_noexecstack()) {
1832 if (!is_init_completed()) {
1833 os::Linux::_stack_is_executable = true;
1834 // This is OK - No Java threads have been created yet, and hence no
1835 // stack guard pages to fix.
1836 //
1837 // This should happen only when you are building JDK7 using a very
1838 // old version of JDK6 (e.g., with JPRT) and running test_gamma.
1839 //
1840 // Dynamic loader will make all stacks executable after
1841 // this function returns, and will not do that again.
1842 assert(Threads::first() == NULL, "no Java threads should exist yet.");
1843 } else {
1844 warning("You have loaded library %s which might have disabled stack guard. "
1845 "The VM will try to fix the stack guard now.\n"
1846 "It's highly recommended that you fix the library with "
1847 "'execstack -c <libfile>', or link it with '-z noexecstack'.",
1848 filename);
1849
1850 assert(Thread::current()->is_Java_thread(), "must be Java thread");
1851 JavaThread *jt = JavaThread::current();
1852 if (jt->thread_state() != _thread_in_native) {
1853 // This happens when a compiler thread tries to load a hsdis-<arch>.so file
1854 // that requires ExecStack. Cannot enter safe point. Let's give up.
1855 warning("Unable to fix stack guard. Giving up.");
1856 } else {
1857 if (!LoadExecStackDllInVMThread) {
1858 // This is for the case where the DLL has an static
1859 // constructor function that executes JNI code. We cannot
1860 // load such DLLs in the VMThread.
1861 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen);
1862 }
1863
1864 ThreadInVMfromNative tiv(jt);
1865 debug_only(VMNativeEntryWrapper vew;)
1866
1867 VM_LinuxDllLoad op(filename, ebuf, ebuflen);
1868 VMThread::execute(&op);
1869 if (LoadExecStackDllInVMThread) {
1870 result = op.loaded_library();
1871 }
1872 load_attempted = true;
1873 }
1874 }
1875 }
1876 }
1877
1878 if (!load_attempted) {
1879 result = os::Linux::dlopen_helper(filename, ebuf, ebuflen);
1880 }
1881
1882 if (result != NULL) {
1883 // Successful loading
1884 return result;
1885 }
1886
1887 Elf32_Ehdr elf_head;
1888 int diag_msg_max_length=ebuflen-strlen(ebuf);
1889 char* diag_msg_buf=ebuf+strlen(ebuf);
1890
1891 if (diag_msg_max_length==0) {
1892 // No more space in ebuf for additional diagnostics message
1893 return NULL;
1894 }
1895
1896
1897 int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK);
1898
1899 if (file_descriptor < 0) {
1900 // Can't open library, report dlerror() message
1901 return NULL;
1902 }
1903
1904 bool failed_to_read_elf_head=
1905 (sizeof(elf_head)!=
1906 (::read(file_descriptor, &elf_head,sizeof(elf_head)))) ;
1907
1908 ::close(file_descriptor);
1909 if (failed_to_read_elf_head) {
1910 // file i/o error - report dlerror() msg
1911 return NULL;
1912 }
1913
1914 typedef struct {
1915 Elf32_Half code; // Actual value as defined in elf.h
1916 Elf32_Half compat_class; // Compatibility of archs at VM's sense
1917 char elf_class; // 32 or 64 bit
1918 char endianess; // MSB or LSB
1919 char* name; // String representation
1920 } arch_t;
1921
1922 #ifndef EM_486
1923 #define EM_486 6 /* Intel 80486 */
1924 #endif
1925
1926 static const arch_t arch_array[]={
1927 {EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
1928 {EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
1929 {EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"},
1930 {EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"},
1931 {EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
1932 {EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
1933 {EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"},
1934 {EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"},
1935 #if defined(VM_LITTLE_ENDIAN)
1936 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2LSB, (char*)"Power PC 64"},
1937 #else
1938 {EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"},
1939 #endif
1940 {EM_ARM, EM_ARM, ELFCLASS32, ELFDATA2LSB, (char*)"ARM"},
1941 {EM_S390, EM_S390, ELFCLASSNONE, ELFDATA2MSB, (char*)"IBM System/390"},
1942 {EM_ALPHA, EM_ALPHA, ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"},
1943 {EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"},
1944 {EM_MIPS, EM_MIPS, ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"},
1945 {EM_PARISC, EM_PARISC, ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"},
1946 {EM_68K, EM_68K, ELFCLASS32, ELFDATA2MSB, (char*)"M68k"}
1947 };
1948
1949 #if (defined IA32)
1950 static Elf32_Half running_arch_code=EM_386;
1951 #elif (defined AMD64)
1952 static Elf32_Half running_arch_code=EM_X86_64;
1953 #elif (defined IA64)
1954 static Elf32_Half running_arch_code=EM_IA_64;
1955 #elif (defined __sparc) && (defined _LP64)
1956 static Elf32_Half running_arch_code=EM_SPARCV9;
1957 #elif (defined __sparc) && (!defined _LP64)
1958 static Elf32_Half running_arch_code=EM_SPARC;
1959 #elif (defined __powerpc64__)
1960 static Elf32_Half running_arch_code=EM_PPC64;
1961 #elif (defined __powerpc__)
1962 static Elf32_Half running_arch_code=EM_PPC;
1963 #elif (defined ARM)
1964 static Elf32_Half running_arch_code=EM_ARM;
1965 #elif (defined S390)
1966 static Elf32_Half running_arch_code=EM_S390;
1967 #elif (defined ALPHA)
1968 static Elf32_Half running_arch_code=EM_ALPHA;
1969 #elif (defined MIPSEL)
1970 static Elf32_Half running_arch_code=EM_MIPS_RS3_LE;
1971 #elif (defined PARISC)
1972 static Elf32_Half running_arch_code=EM_PARISC;
1973 #elif (defined MIPS)
1974 static Elf32_Half running_arch_code=EM_MIPS;
1975 #elif (defined M68K)
1976 static Elf32_Half running_arch_code=EM_68K;
1977 #else
1978 #error Method os::dll_load requires that one of following is defined:\
1979 IA32, AMD64, IA64, __sparc, __powerpc__, ARM, S390, ALPHA, MIPS, MIPSEL, PARISC, M68K
1980 #endif
1981
1982 // Identify compatability class for VM's architecture and library's architecture
1983 // Obtain string descriptions for architectures
1984
1985 arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL};
1986 int running_arch_index=-1;
1987
1988 for (unsigned int i=0 ; i < ARRAY_SIZE(arch_array) ; i++ ) {
1989 if (running_arch_code == arch_array[i].code) {
1990 running_arch_index = i;
1991 }
1992 if (lib_arch.code == arch_array[i].code) {
1993 lib_arch.compat_class = arch_array[i].compat_class;
1994 lib_arch.name = arch_array[i].name;
1995 }
1996 }
1997
1998 assert(running_arch_index != -1,
1999 "Didn't find running architecture code (running_arch_code) in arch_array");
2000 if (running_arch_index == -1) {
2001 // Even though running architecture detection failed
2002 // we may still continue with reporting dlerror() message
2003 return NULL;
2004 }
2005
2006 if (lib_arch.endianess != arch_array[running_arch_index].endianess) {
2007 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)");
2008 return NULL;
2009 }
2010
2011 #ifndef S390
2012 if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) {
2013 ::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)");
2014 return NULL;
2015 }
2016 #endif // !S390
2017
2018 if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) {
2019 if ( lib_arch.name!=NULL ) {
2020 ::snprintf(diag_msg_buf, diag_msg_max_length-1,
2021 " (Possible cause: can't load %s-bit .so on a %s-bit platform)",
2022 lib_arch.name, arch_array[running_arch_index].name);
2023 } else {
2024 ::snprintf(diag_msg_buf, diag_msg_max_length-1,
2025 " (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)",
2026 lib_arch.code,
2027 arch_array[running_arch_index].name);
2028 }
2029 }
2030
2031 return NULL;
2032 }
2033
2034 void * os::Linux::dlopen_helper(const char *filename, char *ebuf, int ebuflen) {
2035 void * result = ::dlopen(filename, RTLD_LAZY);
2036 if (result == NULL) {
2037 ::strncpy(ebuf, ::dlerror(), ebuflen - 1);
2038 ebuf[ebuflen-1] = '\0';
2039 }
2040 return result;
2041 }
2042
2043 void * os::Linux::dll_load_in_vmthread(const char *filename, char *ebuf, int ebuflen) {
2044 void * result = NULL;
2045 if (LoadExecStackDllInVMThread) {
2046 result = dlopen_helper(filename, ebuf, ebuflen);
2047 }
2048
2049 // Since 7019808, libjvm.so is linked with -noexecstack. If the VM loads a
2050 // library that requires an executable stack, or which does not have this
2051 // stack attribute set, dlopen changes the stack attribute to executable. The
2052 // read protection of the guard pages gets lost.
2053 //
2054 // Need to check _stack_is_executable again as multiple VM_LinuxDllLoad
2055 // may have been queued at the same time.
2056
2057 if (!_stack_is_executable) {
2058 JavaThread *jt = Threads::first();
2059
2060 while (jt) {
2061 if (!jt->stack_guard_zone_unused() && // Stack not yet fully initialized
2062 jt->stack_yellow_zone_enabled()) { // No pending stack overflow exceptions
2063 if (!os::guard_memory((char *) jt->stack_red_zone_base() - jt->stack_red_zone_size(),
2064 jt->stack_yellow_zone_size() + jt->stack_red_zone_size())) {
2065 warning("Attempt to reguard stack yellow zone failed.");
2066 }
2067 }
2068 jt = jt->next();
2069 }
2070 }
2071
2072 return result;
2073 }
2074
2075 /*
2076 * glibc-2.0 libdl is not MT safe. If you are building with any glibc,
2077 * chances are you might want to run the generated bits against glibc-2.0
2078 * libdl.so, so always use locking for any version of glibc.
2079 */
2080 void* os::dll_lookup(void* handle, const char* name) {
2081 pthread_mutex_lock(&dl_mutex);
2082 void* res = dlsym(handle, name);
2083 pthread_mutex_unlock(&dl_mutex);
2084 return res;
2085 }
2086
2087 void* os::get_default_process_handle() {
2088 return (void*)::dlopen(NULL, RTLD_LAZY);
2089 }
2090
2091 static bool _print_ascii_file(const char* filename, outputStream* st) {
2092 int fd = ::open(filename, O_RDONLY);
2093 if (fd == -1) {
2094 return false;
2095 }
2096
2097 char buf[32];
2098 int bytes;
2099 while ((bytes = ::read(fd, buf, sizeof(buf))) > 0) {
2100 st->print_raw(buf, bytes);
2101 }
2102
2103 ::close(fd);
2104
2105 return true;
2106 }
2107
2108 void os::print_dll_info(outputStream *st) {
2109 st->print_cr("Dynamic libraries:");
2110
2111 char fname[32];
2112 pid_t pid = os::Linux::gettid();
2113
2114 jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid);
2115
2116 if (!_print_ascii_file(fname, st)) {
2117 st->print("Can not get library information for pid = %d\n", pid);
2118 }
2119 }
2120
2121 void os::print_os_info_brief(outputStream* st) {
2122 os::Linux::print_distro_info(st);
2123
2124 os::Posix::print_uname_info(st);
2125
2126 os::Linux::print_libversion_info(st);
2127
2128 }
2129
2130 void os::print_os_info(outputStream* st) {
2131 st->print("OS:");
2132
2133 os::Linux::print_distro_info(st);
2134
2135 os::Posix::print_uname_info(st);
2136
2137 // Print warning if unsafe chroot environment detected
2138 if (unsafe_chroot_detected) {
2139 st->print("WARNING!! ");
2140 st->print_cr(unstable_chroot_error);
2141 }
2142
2143 os::Linux::print_libversion_info(st);
2144
2145 os::Posix::print_rlimit_info(st);
2146
2147 os::Posix::print_load_average(st);
2148
2149 os::Linux::print_full_memory_info(st);
2150 }
2151
2152 // Try to identify popular distros.
2153 // Most Linux distributions have a /etc/XXX-release file, which contains
2154 // the OS version string. Newer Linux distributions have a /etc/lsb-release
2155 // file that also contains the OS version string. Some have more than one
2156 // /etc/XXX-release file (e.g. Mandrake has both /etc/mandrake-release and
2157 // /etc/redhat-release.), so the order is important.
2158 // Any Linux that is based on Redhat (i.e. Oracle, Mandrake, Sun JDS...) have
2159 // their own specific XXX-release file as well as a redhat-release file.
2160 // Because of this the XXX-release file needs to be searched for before the
2161 // redhat-release file.
2162 // Since Red Hat has a lsb-release file that is not very descriptive the
2163 // search for redhat-release needs to be before lsb-release.
2164 // Since the lsb-release file is the new standard it needs to be searched
2165 // before the older style release files.
2166 // Searching system-release (Red Hat) and os-release (other Linuxes) are a
2167 // next to last resort. The os-release file is a new standard that contains
2168 // distribution information and the system-release file seems to be an old
2169 // standard that has been replaced by the lsb-release and os-release files.
2170 // Searching for the debian_version file is the last resort. It contains
2171 // an informative string like "6.0.6" or "wheezy/sid". Because of this
2172 // "Debian " is printed before the contents of the debian_version file.
2173 void os::Linux::print_distro_info(outputStream* st) {
2174 if (!_print_ascii_file("/etc/oracle-release", st) &&
2175 !_print_ascii_file("/etc/mandriva-release", st) &&
2176 !_print_ascii_file("/etc/mandrake-release", st) &&
2177 !_print_ascii_file("/etc/sun-release", st) &&
2178 !_print_ascii_file("/etc/redhat-release", st) &&
2179 !_print_ascii_file("/etc/lsb-release", st) &&
2180 !_print_ascii_file("/etc/SuSE-release", st) &&
2181 !_print_ascii_file("/etc/turbolinux-release", st) &&
2182 !_print_ascii_file("/etc/gentoo-release", st) &&
2183 !_print_ascii_file("/etc/ltib-release", st) &&
2184 !_print_ascii_file("/etc/angstrom-version", st) &&
2185 !_print_ascii_file("/etc/system-release", st) &&
2186 !_print_ascii_file("/etc/os-release", st)) {
2187
2188 if (file_exists("/etc/debian_version")) {
2189 st->print("Debian ");
2190 _print_ascii_file("/etc/debian_version", st);
2191 } else {
2192 st->print("Linux");
2193 }
2194 }
2195 st->cr();
2196 }
2197
2198 void os::Linux::print_libversion_info(outputStream* st) {
2199 // libc, pthread
2200 st->print("libc:");
2201 st->print(os::Linux::glibc_version()); st->print(" ");
2202 st->print(os::Linux::libpthread_version()); st->print(" ");
2203 if (os::Linux::is_LinuxThreads()) {
2204 st->print("(%s stack)", os::Linux::is_floating_stack() ? "floating" : "fixed");
2205 }
2206 st->cr();
2207 }
2208
2209 void os::Linux::print_full_memory_info(outputStream* st) {
2210 st->print("\n/proc/meminfo:\n");
2211 _print_ascii_file("/proc/meminfo", st);
2212 st->cr();
2213 }
2214
2215 void os::print_memory_info(outputStream* st) {
2216
2217 st->print("Memory:");
2218 st->print(" %dk page", os::vm_page_size()>>10);
2219
2220 // values in struct sysinfo are "unsigned long"
2221 struct sysinfo si;
2222 sysinfo(&si);
2223
2224 st->print(", physical " UINT64_FORMAT "k",
2225 os::physical_memory() >> 10);
2226 st->print("(" UINT64_FORMAT "k free)",
2227 os::available_memory() >> 10);
2228 st->print(", swap " UINT64_FORMAT "k",
2229 ((jlong)si.totalswap * si.mem_unit) >> 10);
2230 st->print("(" UINT64_FORMAT "k free)",
2231 ((jlong)si.freeswap * si.mem_unit) >> 10);
2232 st->cr();
2233 }
2234
2235 void os::pd_print_cpu_info(outputStream* st) {
2236 st->print("\n/proc/cpuinfo:\n");
2237 if (!_print_ascii_file("/proc/cpuinfo", st)) {
2238 st->print(" <Not Available>");
2239 }
2240 st->cr();
2241 }
2242
2243 void os::print_siginfo(outputStream* st, void* siginfo) {
2244 const siginfo_t* si = (const siginfo_t*)siginfo;
2245
2246 os::Posix::print_siginfo_brief(st, si);
2247
2248 if (si && (si->si_signo == SIGBUS || si->si_signo == SIGSEGV) &&
2249 UseSharedSpaces) {
2250 FileMapInfo* mapinfo = FileMapInfo::current_info();
2251 if (mapinfo->is_in_shared_space(si->si_addr)) {
2252 st->print("\n\nError accessing class data sharing archive." \
2253 " Mapped file inaccessible during execution, " \
2254 " possible disk/network problem.");
2255 }
2256 }
2257 st->cr();
2258 }
2259
2260
2261 static void print_signal_handler(outputStream* st, int sig,
2262 char* buf, size_t buflen);
2263
2264 void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) {
2265 st->print_cr("Signal Handlers:");
2266 print_signal_handler(st, SIGSEGV, buf, buflen);
2267 print_signal_handler(st, SIGBUS , buf, buflen);
2268 print_signal_handler(st, SIGFPE , buf, buflen);
2269 print_signal_handler(st, SIGPIPE, buf, buflen);
2270 print_signal_handler(st, SIGXFSZ, buf, buflen);
2271 print_signal_handler(st, SIGILL , buf, buflen);
2272 print_signal_handler(st, INTERRUPT_SIGNAL, buf, buflen);
2273 print_signal_handler(st, SR_signum, buf, buflen);
2274 print_signal_handler(st, SHUTDOWN1_SIGNAL, buf, buflen);
2275 print_signal_handler(st, SHUTDOWN2_SIGNAL , buf, buflen);
2276 print_signal_handler(st, SHUTDOWN3_SIGNAL , buf, buflen);
2277 print_signal_handler(st, BREAK_SIGNAL, buf, buflen);
2278 #if defined(PPC64)
2279 print_signal_handler(st, SIGTRAP, buf, buflen);
2280 #endif
2281 }
2282
2283 static char saved_jvm_path[MAXPATHLEN] = {0};
2284
2285 // Find the full path to the current module, libjvm.so
2286 void os::jvm_path(char *buf, jint buflen) {
2287 // Error checking.
2288 if (buflen < MAXPATHLEN) {
2289 assert(false, "must use a large-enough buffer");
2290 buf[0] = '\0';
2291 return;
2292 }
2293 // Lazy resolve the path to current module.
2294 if (saved_jvm_path[0] != 0) {
2295 strcpy(buf, saved_jvm_path);
2296 return;
2297 }
2298
2299 char dli_fname[MAXPATHLEN];
2300 bool ret = dll_address_to_library_name(
2301 CAST_FROM_FN_PTR(address, os::jvm_path),
2302 dli_fname, sizeof(dli_fname), NULL);
2303 assert(ret, "cannot locate libjvm");
2304 char *rp = NULL;
2305 if (ret && dli_fname[0] != '\0') {
2306 rp = realpath(dli_fname, buf);
2307 }
2308 if (rp == NULL)
2309 return;
2310
2311 if (Arguments::sun_java_launcher_is_altjvm()) {
2312 // Support for the java launcher's '-XXaltjvm=<path>' option. Typical
2313 // value for buf is "<JAVA_HOME>/jre/lib/<arch>/<vmtype>/libjvm.so".
2314 // If "/jre/lib/" appears at the right place in the string, then
2315 // assume we are installed in a JDK and we're done. Otherwise, check
2316 // for a JAVA_HOME environment variable and fix up the path so it
2317 // looks like libjvm.so is installed there (append a fake suffix
2318 // hotspot/libjvm.so).
2319 const char *p = buf + strlen(buf) - 1;
2320 for (int count = 0; p > buf && count < 5; ++count) {
2321 for (--p; p > buf && *p != '/'; --p)
2322 /* empty */ ;
2323 }
2324
2325 if (strncmp(p, "/jre/lib/", 9) != 0) {
2326 // Look for JAVA_HOME in the environment.
2327 char* java_home_var = ::getenv("JAVA_HOME");
2328 if (java_home_var != NULL && java_home_var[0] != 0) {
2329 char* jrelib_p;
2330 int len;
2331
2332 // Check the current module name "libjvm.so".
2333 p = strrchr(buf, '/');
2334 assert(strstr(p, "/libjvm") == p, "invalid library name");
2335
2336 rp = realpath(java_home_var, buf);
2337 if (rp == NULL)
2338 return;
2339
2340 // determine if this is a legacy image or modules image
2341 // modules image doesn't have "jre" subdirectory
2342 len = strlen(buf);
2343 jrelib_p = buf + len;
2344 snprintf(jrelib_p, buflen-len, "/jre/lib/%s", cpu_arch);
2345 if (0 != access(buf, F_OK)) {
2346 snprintf(jrelib_p, buflen-len, "/lib/%s", cpu_arch);
2347 }
2348
2349 if (0 == access(buf, F_OK)) {
2350 // Use current module name "libjvm.so"
2351 len = strlen(buf);
2352 snprintf(buf + len, buflen-len, "/hotspot/libjvm.so");
2353 } else {
2354 // Go back to path of .so
2355 rp = realpath(dli_fname, buf);
2356 if (rp == NULL)
2357 return;
2358 }
2359 }
2360 }
2361 }
2362
2363 strcpy(saved_jvm_path, buf);
2364 }
2365
2366 void os::print_jni_name_prefix_on(outputStream* st, int args_size) {
2367 // no prefix required, not even "_"
2368 }
2369
2370 void os::print_jni_name_suffix_on(outputStream* st, int args_size) {
2371 // no suffix required
2372 }
2373
2374 ////////////////////////////////////////////////////////////////////////////////
2375 // sun.misc.Signal support
2376
2377 static volatile jint sigint_count = 0;
2378
2379 static void
2380 UserHandler(int sig, void *siginfo, void *context) {
2381 // 4511530 - sem_post is serialized and handled by the manager thread. When
2382 // the program is interrupted by Ctrl-C, SIGINT is sent to every thread. We
2383 // don't want to flood the manager thread with sem_post requests.
2384 if (sig == SIGINT && Atomic::add(1, &sigint_count) > 1)
2385 return;
2386
2387 // Ctrl-C is pressed during error reporting, likely because the error
2388 // handler fails to abort. Let VM die immediately.
2389 if (sig == SIGINT && is_error_reported()) {
2390 os::die();
2391 }
2392
2393 os::signal_notify(sig);
2394 }
2395
2396 void* os::user_handler() {
2397 return CAST_FROM_FN_PTR(void*, UserHandler);
2398 }
2399
2400 class Semaphore : public StackObj {
2401 public:
2402 Semaphore();
2403 ~Semaphore();
2404 void signal();
2405 void wait();
2406 bool trywait();
2407 bool timedwait(unsigned int sec, int nsec);
2408 private:
2409 sem_t _semaphore;
2410 };
2411
2412 Semaphore::Semaphore() {
2413 sem_init(&_semaphore, 0, 0);
2414 }
2415
2416 Semaphore::~Semaphore() {
2417 sem_destroy(&_semaphore);
2418 }
2419
2420 void Semaphore::signal() {
2421 sem_post(&_semaphore);
2422 }
2423
2424 void Semaphore::wait() {
2425 sem_wait(&_semaphore);
2426 }
2427
2428 bool Semaphore::trywait() {
2429 return sem_trywait(&_semaphore) == 0;
2430 }
2431
2432 bool Semaphore::timedwait(unsigned int sec, int nsec) {
2433
2434 struct timespec ts;
2435 // Semaphore's are always associated with CLOCK_REALTIME
2436 os::Linux::clock_gettime(CLOCK_REALTIME, &ts);
2437 // see unpackTime for discussion on overflow checking
2438 if (sec >= MAX_SECS) {
2439 ts.tv_sec += MAX_SECS;
2440 ts.tv_nsec = 0;
2441 } else {
2442 ts.tv_sec += sec;
2443 ts.tv_nsec += nsec;
2444 if (ts.tv_nsec >= NANOSECS_PER_SEC) {
2445 ts.tv_nsec -= NANOSECS_PER_SEC;
2446 ++ts.tv_sec; // note: this must be <= max_secs
2447 }
2448 }
2449
2450 while (1) {
2451 int result = sem_timedwait(&_semaphore, &ts);
2452 if (result == 0) {
2453 return true;
2454 } else if (errno == EINTR) {
2455 continue;
2456 } else if (errno == ETIMEDOUT) {
2457 return false;
2458 } else {
2459 return false;
2460 }
2461 }
2462 }
2463
2464 extern "C" {
2465 typedef void (*sa_handler_t)(int);
2466 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *);
2467 }
2468
2469 void* os::signal(int signal_number, void* handler) {
2470 struct sigaction sigAct, oldSigAct;
2471
2472 sigfillset(&(sigAct.sa_mask));
2473 sigAct.sa_flags = SA_RESTART|SA_SIGINFO;
2474 sigAct.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler);
2475
2476 if (sigaction(signal_number, &sigAct, &oldSigAct)) {
2477 // -1 means registration failed
2478 return (void *)-1;
2479 }
2480
2481 return CAST_FROM_FN_PTR(void*, oldSigAct.sa_handler);
2482 }
2483
2484 void os::signal_raise(int signal_number) {
2485 ::raise(signal_number);
2486 }
2487
2488 /*
2489 * The following code is moved from os.cpp for making this
2490 * code platform specific, which it is by its very nature.
2491 */
2492
2493 // Will be modified when max signal is changed to be dynamic
2494 int os::sigexitnum_pd() {
2495 return NSIG;
2496 }
2497
2498 // a counter for each possible signal value
2499 static volatile jint pending_signals[NSIG+1] = { 0 };
2500
2501 // Linux(POSIX) specific hand shaking semaphore.
2502 static sem_t sig_sem;
2503 static Semaphore sr_semaphore;
2504
2505 void os::signal_init_pd() {
2506 // Initialize signal structures
2507 ::memset((void*)pending_signals, 0, sizeof(pending_signals));
2508
2509 // Initialize signal semaphore
2510 ::sem_init(&sig_sem, 0, 0);
2511 }
2512
2513 void os::signal_notify(int sig) {
2514 Atomic::inc(&pending_signals[sig]);
2515 ::sem_post(&sig_sem);
2516 }
2517
2518 static int check_pending_signals(bool wait) {
2519 Atomic::store(0, &sigint_count);
2520 for (;;) {
2521 for (int i = 0; i < NSIG + 1; i++) {
2522 jint n = pending_signals[i];
2523 if (n > 0 && n == Atomic::cmpxchg(n - 1, &pending_signals[i], n)) {
2524 return i;
2525 }
2526 }
2527 if (!wait) {
2528 return -1;
2529 }
2530 JavaThread *thread = JavaThread::current();
2531 ThreadBlockInVM tbivm(thread);
2532
2533 bool threadIsSuspended;
2534 do {
2535 thread->set_suspend_equivalent();
2536 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
2537 ::sem_wait(&sig_sem);
2538
2539 // were we externally suspended while we were waiting?
2540 threadIsSuspended = thread->handle_special_suspend_equivalent_condition();
2541 if (threadIsSuspended) {
2542 //
2543 // The semaphore has been incremented, but while we were waiting
2544 // another thread suspended us. We don't want to continue running
2545 // while suspended because that would surprise the thread that
2546 // suspended us.
2547 //
2548 ::sem_post(&sig_sem);
2549
2550 thread->java_suspend_self();
2551 }
2552 } while (threadIsSuspended);
2553 }
2554 }
2555
2556 int os::signal_lookup() {
2557 return check_pending_signals(false);
2558 }
2559
2560 int os::signal_wait() {
2561 return check_pending_signals(true);
2562 }
2563
2564 ////////////////////////////////////////////////////////////////////////////////
2565 // Virtual Memory
2566
2567 int os::vm_page_size() {
2568 // Seems redundant as all get out
2569 assert(os::Linux::page_size() != -1, "must call os::init");
2570 return os::Linux::page_size();
2571 }
2572
2573 // Solaris allocates memory by pages.
2574 int os::vm_allocation_granularity() {
2575 assert(os::Linux::page_size() != -1, "must call os::init");
2576 return os::Linux::page_size();
2577 }
2578
2579 // Rationale behind this function:
2580 // current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable
2581 // mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get
2582 // samples for JITted code. Here we create private executable mapping over the code cache
2583 // and then we can use standard (well, almost, as mapping can change) way to provide
2584 // info for the reporting script by storing timestamp and location of symbol
2585 void linux_wrap_code(char* base, size_t size) {
2586 static volatile jint cnt = 0;
2587
2588 if (!UseOprofile) {
2589 return;
2590 }
2591
2592 char buf[PATH_MAX+1];
2593 int num = Atomic::add(1, &cnt);
2594
2595 snprintf(buf, sizeof(buf), "%s/hs-vm-%d-%d",
2596 os::get_temp_directory(), os::current_process_id(), num);
2597 unlink(buf);
2598
2599 int fd = ::open(buf, O_CREAT | O_RDWR, S_IRWXU);
2600
2601 if (fd != -1) {
2602 off_t rv = ::lseek(fd, size-2, SEEK_SET);
2603 if (rv != (off_t)-1) {
2604 if (::write(fd, "", 1) == 1) {
2605 mmap(base, size,
2606 PROT_READ|PROT_WRITE|PROT_EXEC,
2607 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0);
2608 }
2609 }
2610 ::close(fd);
2611 unlink(buf);
2612 }
2613 }
2614
2615 static bool recoverable_mmap_error(int err) {
2616 // See if the error is one we can let the caller handle. This
2617 // list of errno values comes from JBS-6843484. I can't find a
2618 // Linux man page that documents this specific set of errno
2619 // values so while this list currently matches Solaris, it may
2620 // change as we gain experience with this failure mode.
2621 switch (err) {
2622 case EBADF:
2623 case EINVAL:
2624 case ENOTSUP:
2625 // let the caller deal with these errors
2626 return true;
2627
2628 default:
2629 // Any remaining errors on this OS can cause our reserved mapping
2630 // to be lost. That can cause confusion where different data
2631 // structures think they have the same memory mapped. The worst
2632 // scenario is if both the VM and a library think they have the
2633 // same memory mapped.
2634 return false;
2635 }
2636 }
2637
2638 static void warn_fail_commit_memory(char* addr, size_t size, bool exec,
2639 int err) {
2640 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT
2641 ", %d) failed; error='%s' (errno=%d)", addr, size, exec,
2642 strerror(err), err);
2643 }
2644
2645 static void warn_fail_commit_memory(char* addr, size_t size,
2646 size_t alignment_hint, bool exec,
2647 int err) {
2648 warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT
2649 ", " SIZE_FORMAT ", %d) failed; error='%s' (errno=%d)", addr, size,
2650 alignment_hint, exec, strerror(err), err);
2651 }
2652
2653 // NOTE: Linux kernel does not really reserve the pages for us.
2654 // All it does is to check if there are enough free pages
2655 // left at the time of mmap(). This could be a potential
2656 // problem.
2657 int os::Linux::commit_memory_impl(char* addr, size_t size, bool exec) {
2658 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
2659 uintptr_t res = (uintptr_t) ::mmap(addr, size, prot,
2660 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0);
2661 if (res != (uintptr_t) MAP_FAILED) {
2662 if (UseNUMAInterleaving) {
2663 numa_make_global(addr, size);
2664 }
2665 return 0;
2666 }
2667
2668 int err = errno; // save errno from mmap() call above
2669
2670 if (!recoverable_mmap_error(err)) {
2671 warn_fail_commit_memory(addr, size, exec, err);
2672 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, "committing reserved memory.");
2673 }
2674
2675 return err;
2676 }
2677
2678 bool os::pd_commit_memory(char* addr, size_t size, bool exec) {
2679 return os::Linux::commit_memory_impl(addr, size, exec) == 0;
2680 }
2681
2682 void os::pd_commit_memory_or_exit(char* addr, size_t size, bool exec,
2683 const char* mesg) {
2684 assert(mesg != NULL, "mesg must be specified");
2685 int err = os::Linux::commit_memory_impl(addr, size, exec);
2686 if (err != 0) {
2687 // the caller wants all commit errors to exit with the specified mesg:
2688 warn_fail_commit_memory(addr, size, exec, err);
2689 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg);
2690 }
2691 }
2692
2693 // Define MAP_HUGETLB here so we can build HotSpot on old systems.
2694 #ifndef MAP_HUGETLB
2695 #define MAP_HUGETLB 0x40000
2696 #endif
2697
2698 // Define MADV_HUGEPAGE here so we can build HotSpot on old systems.
2699 #ifndef MADV_HUGEPAGE
2700 #define MADV_HUGEPAGE 14
2701 #endif
2702
2703 int os::Linux::commit_memory_impl(char* addr, size_t size,
2704 size_t alignment_hint, bool exec) {
2705 int err = os::Linux::commit_memory_impl(addr, size, exec);
2706 if (err == 0) {
2707 realign_memory(addr, size, alignment_hint);
2708 }
2709 return err;
2710 }
2711
2712 bool os::pd_commit_memory(char* addr, size_t size, size_t alignment_hint,
2713 bool exec) {
2714 return os::Linux::commit_memory_impl(addr, size, alignment_hint, exec) == 0;
2715 }
2716
2717 void os::pd_commit_memory_or_exit(char* addr, size_t size,
2718 size_t alignment_hint, bool exec,
2719 const char* mesg) {
2720 assert(mesg != NULL, "mesg must be specified");
2721 int err = os::Linux::commit_memory_impl(addr, size, alignment_hint, exec);
2722 if (err != 0) {
2723 // the caller wants all commit errors to exit with the specified mesg:
2724 warn_fail_commit_memory(addr, size, alignment_hint, exec, err);
2725 vm_exit_out_of_memory(size, OOM_MMAP_ERROR, mesg);
2726 }
2727 }
2728
2729 void os::pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint) {
2730 if (UseTransparentHugePages && alignment_hint > (size_t)vm_page_size()) {
2731 // We don't check the return value: madvise(MADV_HUGEPAGE) may not
2732 // be supported or the memory may already be backed by huge pages.
2733 ::madvise(addr, bytes, MADV_HUGEPAGE);
2734 }
2735 }
2736
2737 void os::pd_free_memory(char *addr, size_t bytes, size_t alignment_hint) {
2738 // This method works by doing an mmap over an existing mmaping and effectively discarding
2739 // the existing pages. However it won't work for SHM-based large pages that cannot be
2740 // uncommitted at all. We don't do anything in this case to avoid creating a segment with
2741 // small pages on top of the SHM segment. This method always works for small pages, so we
2742 // allow that in any case.
2743 if (alignment_hint <= (size_t)os::vm_page_size() || can_commit_large_page_memory()) {
2744 commit_memory(addr, bytes, alignment_hint, !ExecMem);
2745 }
2746 }
2747
2748 void os::numa_make_global(char *addr, size_t bytes) {
2749 Linux::numa_interleave_memory(addr, bytes);
2750 }
2751
2752 // Define for numa_set_bind_policy(int). Setting the argument to 0 will set the
2753 // bind policy to MPOL_PREFERRED for the current thread.
2754 #define USE_MPOL_PREFERRED 0
2755
2756 void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) {
2757 // To make NUMA and large pages more robust when both enabled, we need to ease
2758 // the requirements on where the memory should be allocated. MPOL_BIND is the
2759 // default policy and it will force memory to be allocated on the specified
2760 // node. Changing this to MPOL_PREFERRED will prefer to allocate the memory on
2761 // the specified node, but will not force it. Using this policy will prevent
2762 // getting SIGBUS when trying to allocate large pages on NUMA nodes with no
2763 // free large pages.
2764 Linux::numa_set_bind_policy(USE_MPOL_PREFERRED);
2765 Linux::numa_tonode_memory(addr, bytes, lgrp_hint);
2766 }
2767
2768 bool os::numa_topology_changed() { return false; }
2769
2770 size_t os::numa_get_groups_num() {
2771 int max_node = Linux::numa_max_node();
2772 return max_node > 0 ? max_node + 1 : 1;
2773 }
2774
2775 int os::numa_get_group_id() {
2776 int cpu_id = Linux::sched_getcpu();
2777 if (cpu_id != -1) {
2778 int lgrp_id = Linux::get_node_by_cpu(cpu_id);
2779 if (lgrp_id != -1) {
2780 return lgrp_id;
2781 }
2782 }
2783 return 0;
2784 }
2785
2786 size_t os::numa_get_leaf_groups(int *ids, size_t size) {
2787 for (size_t i = 0; i < size; i++) {
2788 ids[i] = i;
2789 }
2790 return size;
2791 }
2792
2793 bool os::get_page_info(char *start, page_info* info) {
2794 return false;
2795 }
2796
2797 char *os::scan_pages(char *start, char* end, page_info* page_expected, page_info* page_found) {
2798 return end;
2799 }
2800
2801
2802 int os::Linux::sched_getcpu_syscall(void) {
2803 unsigned int cpu;
2804 int retval = -1;
2805
2806 #if defined(IA32)
2807 # ifndef SYS_getcpu
2808 # define SYS_getcpu 318
2809 # endif
2810 retval = syscall(SYS_getcpu, &cpu, NULL, NULL);
2811 #elif defined(AMD64)
2812 // Unfortunately we have to bring all these macros here from vsyscall.h
2813 // to be able to compile on old linuxes.
2814 # define __NR_vgetcpu 2
2815 # define VSYSCALL_START (-10UL << 20)
2816 # define VSYSCALL_SIZE 1024
2817 # define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr))
2818 typedef long (*vgetcpu_t)(unsigned int *cpu, unsigned int *node, unsigned long *tcache);
2819 vgetcpu_t vgetcpu = (vgetcpu_t)VSYSCALL_ADDR(__NR_vgetcpu);
2820 retval = vgetcpu(&cpu, NULL, NULL);
2821 #endif
2822
2823 return (retval == -1) ? retval : cpu;
2824 }
2825
2826 // Something to do with the numa-aware allocator needs these symbols
2827 extern "C" JNIEXPORT void numa_warn(int number, char *where, ...) { }
2828 extern "C" JNIEXPORT void numa_error(char *where) { }
2829 extern "C" JNIEXPORT int fork1() { return fork(); }
2830
2831
2832 // If we are running with libnuma version > 2, then we should
2833 // be trying to use symbols with versions 1.1
2834 // If we are running with earlier version, which did not have symbol versions,
2835 // we should use the base version.
2836 void* os::Linux::libnuma_dlsym(void* handle, const char *name) {
2837 void *f = dlvsym(handle, name, "libnuma_1.1");
2838 if (f == NULL) {
2839 f = dlsym(handle, name);
2840 }
2841 return f;
2842 }
2843
2844 bool os::Linux::libnuma_init() {
2845 // sched_getcpu() should be in libc.
2846 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t,
2847 dlsym(RTLD_DEFAULT, "sched_getcpu")));
2848
2849 // If it's not, try a direct syscall.
2850 if (sched_getcpu() == -1)
2851 set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t, (void*)&sched_getcpu_syscall));
2852
2853 if (sched_getcpu() != -1) { // Does it work?
2854 void *handle = dlopen("libnuma.so.1", RTLD_LAZY);
2855 if (handle != NULL) {
2856 set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t,
2857 libnuma_dlsym(handle, "numa_node_to_cpus")));
2858 set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t,
2859 libnuma_dlsym(handle, "numa_max_node")));
2860 set_numa_available(CAST_TO_FN_PTR(numa_available_func_t,
2861 libnuma_dlsym(handle, "numa_available")));
2862 set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t,
2863 libnuma_dlsym(handle, "numa_tonode_memory")));
2864 set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t,
2865 libnuma_dlsym(handle, "numa_interleave_memory")));
2866 set_numa_set_bind_policy(CAST_TO_FN_PTR(numa_set_bind_policy_func_t,
2867 libnuma_dlsym(handle, "numa_set_bind_policy")));
2868
2869
2870 if (numa_available() != -1) {
2871 set_numa_all_nodes((unsigned long*)libnuma_dlsym(handle, "numa_all_nodes"));
2872 // Create a cpu -> node mapping
2873 _cpu_to_node = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<int>(0, true);
2874 rebuild_cpu_to_node_map();
2875 return true;
2876 }
2877 }
2878 }
2879 return false;
2880 }
2881
2882 // rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id.
2883 // The table is later used in get_node_by_cpu().
2884 void os::Linux::rebuild_cpu_to_node_map() {
2885 const size_t NCPUS = 32768; // Since the buffer size computation is very obscure
2886 // in libnuma (possible values are starting from 16,
2887 // and continuing up with every other power of 2, but less
2888 // than the maximum number of CPUs supported by kernel), and
2889 // is a subject to change (in libnuma version 2 the requirements
2890 // are more reasonable) we'll just hardcode the number they use
2891 // in the library.
2892 const size_t BitsPerCLong = sizeof(long) * CHAR_BIT;
2893
2894 size_t cpu_num = os::active_processor_count();
2895 size_t cpu_map_size = NCPUS / BitsPerCLong;
2896 size_t cpu_map_valid_size =
2897 MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size);
2898
2899 cpu_to_node()->clear();
2900 cpu_to_node()->at_grow(cpu_num - 1);
2901 size_t node_num = numa_get_groups_num();
2902
2903 unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size, mtInternal);
2904 for (size_t i = 0; i < node_num; i++) {
2905 if (numa_node_to_cpus(i, cpu_map, cpu_map_size * sizeof(unsigned long)) != -1) {
2906 for (size_t j = 0; j < cpu_map_valid_size; j++) {
2907 if (cpu_map[j] != 0) {
2908 for (size_t k = 0; k < BitsPerCLong; k++) {
2909 if (cpu_map[j] & (1UL << k)) {
2910 cpu_to_node()->at_put(j * BitsPerCLong + k, i);
2911 }
2912 }
2913 }
2914 }
2915 }
2916 }
2917 FREE_C_HEAP_ARRAY(unsigned long, cpu_map, mtInternal);
2918 }
2919
2920 int os::Linux::get_node_by_cpu(int cpu_id) {
2921 if (cpu_to_node() != NULL && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) {
2922 return cpu_to_node()->at(cpu_id);
2923 }
2924 return -1;
2925 }
2926
2927 GrowableArray<int>* os::Linux::_cpu_to_node;
2928 os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu;
2929 os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus;
2930 os::Linux::numa_max_node_func_t os::Linux::_numa_max_node;
2931 os::Linux::numa_available_func_t os::Linux::_numa_available;
2932 os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory;
2933 os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory;
2934 os::Linux::numa_set_bind_policy_func_t os::Linux::_numa_set_bind_policy;
2935 unsigned long* os::Linux::_numa_all_nodes;
2936
2937 bool os::pd_uncommit_memory(char* addr, size_t size) {
2938 uintptr_t res = (uintptr_t) ::mmap(addr, size, PROT_NONE,
2939 MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0);
2940 return res != (uintptr_t) MAP_FAILED;
2941 }
2942
2943 static
2944 address get_stack_commited_bottom(address bottom, size_t size) {
2945 address nbot = bottom;
2946 address ntop = bottom + size;
2947
2948 size_t page_sz = os::vm_page_size();
2949 unsigned pages = size / page_sz;
2950
2951 unsigned char vec[1];
2952 unsigned imin = 1, imax = pages + 1, imid;
2953 int mincore_return_value = 0;
2954
2955 assert(imin <= imax, "Unexpected page size");
2956
2957 while (imin < imax) {
2958 imid = (imax + imin) / 2;
2959 nbot = ntop - (imid * page_sz);
2960
2961 // Use a trick with mincore to check whether the page is mapped or not.
2962 // mincore sets vec to 1 if page resides in memory and to 0 if page
2963 // is swapped output but if page we are asking for is unmapped
2964 // it returns -1,ENOMEM
2965 mincore_return_value = mincore(nbot, page_sz, vec);
2966
2967 if (mincore_return_value == -1) {
2968 // Page is not mapped go up
2969 // to find first mapped page
2970 if (errno != EAGAIN) {
2971 assert(errno == ENOMEM, "Unexpected mincore errno");
2972 imax = imid;
2973 }
2974 } else {
2975 // Page is mapped go down
2976 // to find first not mapped page
2977 imin = imid + 1;
2978 }
2979 }
2980
2981 nbot = nbot + page_sz;
2982
2983 // Adjust stack bottom one page up if last checked page is not mapped
2984 if (mincore_return_value == -1) {
2985 nbot = nbot + page_sz;
2986 }
2987
2988 return nbot;
2989 }
2990
2991
2992 // Linux uses a growable mapping for the stack, and if the mapping for
2993 // the stack guard pages is not removed when we detach a thread the
2994 // stack cannot grow beyond the pages where the stack guard was
2995 // mapped. If at some point later in the process the stack expands to
2996 // that point, the Linux kernel cannot expand the stack any further
2997 // because the guard pages are in the way, and a segfault occurs.
2998 //
2999 // However, it's essential not to split the stack region by unmapping
3000 // a region (leaving a hole) that's already part of the stack mapping,
3001 // so if the stack mapping has already grown beyond the guard pages at
3002 // the time we create them, we have to truncate the stack mapping.
3003 // So, we need to know the extent of the stack mapping when
3004 // create_stack_guard_pages() is called.
3005
3006 // We only need this for stacks that are growable: at the time of
3007 // writing thread stacks don't use growable mappings (i.e. those
3008 // creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this
3009 // only applies to the main thread.
3010
3011 // If the (growable) stack mapping already extends beyond the point
3012 // where we're going to put our guard pages, truncate the mapping at
3013 // that point by munmap()ping it. This ensures that when we later
3014 // munmap() the guard pages we don't leave a hole in the stack
3015 // mapping. This only affects the main/initial thread
3016
3017 bool os::pd_create_stack_guard_pages(char* addr, size_t size) {
3018
3019 if (os::Linux::is_initial_thread()) {
3020 // As we manually grow stack up to bottom inside create_attached_thread(),
3021 // it's likely that os::Linux::initial_thread_stack_bottom is mapped and
3022 // we don't need to do anything special.
3023 // Check it first, before calling heavy function.
3024 uintptr_t stack_extent = (uintptr_t) os::Linux::initial_thread_stack_bottom();
3025 unsigned char vec[1];
3026
3027 if (mincore((address)stack_extent, os::vm_page_size(), vec) == -1) {
3028 // Fallback to slow path on all errors, including EAGAIN
3029 stack_extent = (uintptr_t) get_stack_commited_bottom(
3030 os::Linux::initial_thread_stack_bottom(),
3031 (size_t)addr - stack_extent);
3032 }
3033
3034 if (stack_extent < (uintptr_t)addr) {
3035 ::munmap((void*)stack_extent, (uintptr_t)(addr - stack_extent));
3036 }
3037 }
3038
3039 return os::commit_memory(addr, size, !ExecMem);
3040 }
3041
3042 // If this is a growable mapping, remove the guard pages entirely by
3043 // munmap()ping them. If not, just call uncommit_memory(). This only
3044 // affects the main/initial thread, but guard against future OS changes
3045 // It's safe to always unmap guard pages for initial thread because we
3046 // always place it right after end of the mapped region
3047
3048 bool os::remove_stack_guard_pages(char* addr, size_t size) {
3049 uintptr_t stack_extent, stack_base;
3050
3051 if (os::Linux::is_initial_thread()) {
3052 return ::munmap(addr, size) == 0;
3053 }
3054
3055 return os::uncommit_memory(addr, size);
3056 }
3057
3058 static address _highest_vm_reserved_address = NULL;
3059
3060 // If 'fixed' is true, anon_mmap() will attempt to reserve anonymous memory
3061 // at 'requested_addr'. If there are existing memory mappings at the same
3062 // location, however, they will be overwritten. If 'fixed' is false,
3063 // 'requested_addr' is only treated as a hint, the return value may or
3064 // may not start from the requested address. Unlike Linux mmap(), this
3065 // function returns NULL to indicate failure.
3066 static char* anon_mmap(char* requested_addr, size_t bytes, bool fixed) {
3067 char * addr;
3068 int flags;
3069
3070 flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS;
3071 if (fixed) {
3072 assert((uintptr_t)requested_addr % os::Linux::page_size() == 0, "unaligned address");
3073 flags |= MAP_FIXED;
3074 }
3075
3076 // Map reserved/uncommitted pages PROT_NONE so we fail early if we
3077 // touch an uncommitted page. Otherwise, the read/write might
3078 // succeed if we have enough swap space to back the physical page.
3079 addr = (char*)::mmap(requested_addr, bytes, PROT_NONE,
3080 flags, -1, 0);
3081
3082 if (addr != MAP_FAILED) {
3083 // anon_mmap() should only get called during VM initialization,
3084 // don't need lock (actually we can skip locking even it can be called
3085 // from multiple threads, because _highest_vm_reserved_address is just a
3086 // hint about the upper limit of non-stack memory regions.)
3087 if ((address)addr + bytes > _highest_vm_reserved_address) {
3088 _highest_vm_reserved_address = (address)addr + bytes;
3089 }
3090 }
3091
3092 return addr == MAP_FAILED ? NULL : addr;
3093 }
3094
3095 // Don't update _highest_vm_reserved_address, because there might be memory
3096 // regions above addr + size. If so, releasing a memory region only creates
3097 // a hole in the address space, it doesn't help prevent heap-stack collision.
3098 //
3099 static int anon_munmap(char * addr, size_t size) {
3100 return ::munmap(addr, size) == 0;
3101 }
3102
3103 char* os::pd_reserve_memory(size_t bytes, char* requested_addr,
3104 size_t alignment_hint) {
3105 return anon_mmap(requested_addr, bytes, (requested_addr != NULL));
3106 }
3107
3108 bool os::pd_release_memory(char* addr, size_t size) {
3109 return anon_munmap(addr, size);
3110 }
3111
3112 static address highest_vm_reserved_address() {
3113 return _highest_vm_reserved_address;
3114 }
3115
3116 static bool linux_mprotect(char* addr, size_t size, int prot) {
3117 // Linux wants the mprotect address argument to be page aligned.
3118 char* bottom = (char*)align_size_down((intptr_t)addr, os::Linux::page_size());
3119
3120 // According to SUSv3, mprotect() should only be used with mappings
3121 // established by mmap(), and mmap() always maps whole pages. Unaligned
3122 // 'addr' likely indicates problem in the VM (e.g. trying to change
3123 // protection of malloc'ed or statically allocated memory). Check the
3124 // caller if you hit this assert.
3125 assert(addr == bottom, "sanity check");
3126
3127 size = align_size_up(pointer_delta(addr, bottom, 1) + size, os::Linux::page_size());
3128 return ::mprotect(bottom, size, prot) == 0;
3129 }
3130
3131 // Set protections specified
3132 bool os::protect_memory(char* addr, size_t bytes, ProtType prot,
3133 bool is_committed) {
3134 unsigned int p = 0;
3135 switch (prot) {
3136 case MEM_PROT_NONE: p = PROT_NONE; break;
3137 case MEM_PROT_READ: p = PROT_READ; break;
3138 case MEM_PROT_RW: p = PROT_READ|PROT_WRITE; break;
3139 case MEM_PROT_RWX: p = PROT_READ|PROT_WRITE|PROT_EXEC; break;
3140 default:
3141 ShouldNotReachHere();
3142 }
3143 // is_committed is unused.
3144 return linux_mprotect(addr, bytes, p);
3145 }
3146
3147 bool os::guard_memory(char* addr, size_t size) {
3148 return linux_mprotect(addr, size, PROT_NONE);
3149 }
3150
3151 bool os::unguard_memory(char* addr, size_t size) {
3152 return linux_mprotect(addr, size, PROT_READ|PROT_WRITE);
3153 }
3154
3155 bool os::Linux::transparent_huge_pages_sanity_check(bool warn, size_t page_size) {
3156 bool result = false;
3157 void *p = mmap(NULL, page_size * 2, PROT_READ|PROT_WRITE,
3158 MAP_ANONYMOUS|MAP_PRIVATE,
3159 -1, 0);
3160 if (p != MAP_FAILED) {
3161 void *aligned_p = align_ptr_up(p, page_size);
3162
3163 result = madvise(aligned_p, page_size, MADV_HUGEPAGE) == 0;
3164
3165 munmap(p, page_size * 2);
3166 }
3167
3168 if (warn && !result) {
3169 warning("TransparentHugePages is not supported by the operating system.");
3170 }
3171
3172 return result;
3173 }
3174
3175 bool os::Linux::hugetlbfs_sanity_check(bool warn, size_t page_size) {
3176 bool result = false;
3177 void *p = mmap(NULL, page_size, PROT_READ|PROT_WRITE,
3178 MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB,
3179 -1, 0);
3180
3181 if (p != MAP_FAILED) {
3182 // We don't know if this really is a huge page or not.
3183 FILE *fp = fopen("/proc/self/maps", "r");
3184 if (fp) {
3185 while (!feof(fp)) {
3186 char chars[257];
3187 long x = 0;
3188 if (fgets(chars, sizeof(chars), fp)) {
3189 if (sscanf(chars, "%lx-%*x", &x) == 1
3190 && x == (long)p) {
3191 if (strstr (chars, "hugepage")) {
3192 result = true;
3193 break;
3194 }
3195 }
3196 }
3197 }
3198 fclose(fp);
3199 }
3200 munmap(p, page_size);
3201 }
3202
3203 if (warn && !result) {
3204 warning("HugeTLBFS is not supported by the operating system.");
3205 }
3206
3207 return result;
3208 }
3209
3210 /*
3211 * Set the coredump_filter bits to include largepages in core dump (bit 6)
3212 *
3213 * From the coredump_filter documentation:
3214 *
3215 * - (bit 0) anonymous private memory
3216 * - (bit 1) anonymous shared memory
3217 * - (bit 2) file-backed private memory
3218 * - (bit 3) file-backed shared memory
3219 * - (bit 4) ELF header pages in file-backed private memory areas (it is
3220 * effective only if the bit 2 is cleared)
3221 * - (bit 5) hugetlb private memory
3222 * - (bit 6) hugetlb shared memory
3223 */
3224 static void set_coredump_filter(void) {
3225 FILE *f;
3226 long cdm;
3227
3228 if ((f = fopen("/proc/self/coredump_filter", "r+")) == NULL) {
3229 return;
3230 }
3231
3232 if (fscanf(f, "%lx", &cdm) != 1) {
3233 fclose(f);
3234 return;
3235 }
3236
3237 rewind(f);
3238
3239 if ((cdm & LARGEPAGES_BIT) == 0) {
3240 cdm |= LARGEPAGES_BIT;
3241 fprintf(f, "%#lx", cdm);
3242 }
3243
3244 fclose(f);
3245 }
3246
3247 // Large page support
3248
3249 static size_t _large_page_size = 0;
3250
3251 size_t os::Linux::find_large_page_size() {
3252 size_t large_page_size = 0;
3253
3254 // large_page_size on Linux is used to round up heap size. x86 uses either
3255 // 2M or 4M page, depending on whether PAE (Physical Address Extensions)
3256 // mode is enabled. AMD64/EM64T uses 2M page in 64bit mode. IA64 can use
3257 // page as large as 256M.
3258 //
3259 // Here we try to figure out page size by parsing /proc/meminfo and looking
3260 // for a line with the following format:
3261 // Hugepagesize: 2048 kB
3262 //
3263 // If we can't determine the value (e.g. /proc is not mounted, or the text
3264 // format has been changed), we'll use the largest page size supported by
3265 // the processor.
3266
3267 #ifndef ZERO
3268 large_page_size = IA32_ONLY(4 * M) AMD64_ONLY(2 * M) IA64_ONLY(256 * M) SPARC_ONLY(4 * M)
3269 ARM_ONLY(2 * M) PPC_ONLY(4 * M);
3270 #endif // ZERO
3271
3272 FILE *fp = fopen("/proc/meminfo", "r");
3273 if (fp) {
3274 while (!feof(fp)) {
3275 int x = 0;
3276 char buf[16];
3277 if (fscanf(fp, "Hugepagesize: %d", &x) == 1) {
3278 if (x && fgets(buf, sizeof(buf), fp) && strcmp(buf, " kB\n") == 0) {
3279 large_page_size = x * K;
3280 break;
3281 }
3282 } else {
3283 // skip to next line
3284 for (;;) {
3285 int ch = fgetc(fp);
3286 if (ch == EOF || ch == (int)'\n') break;
3287 }
3288 }
3289 }
3290 fclose(fp);
3291 }
3292
3293 if (!FLAG_IS_DEFAULT(LargePageSizeInBytes) && LargePageSizeInBytes != large_page_size) {
3294 warning("Setting LargePageSizeInBytes has no effect on this OS. Large page size is "
3295 SIZE_FORMAT "%s.", byte_size_in_proper_unit(large_page_size),
3296 proper_unit_for_byte_size(large_page_size));
3297 }
3298
3299 return large_page_size;
3300 }
3301
3302 size_t os::Linux::setup_large_page_size() {
3303 _large_page_size = Linux::find_large_page_size();
3304 const size_t default_page_size = (size_t)Linux::page_size();
3305 if (_large_page_size > default_page_size) {
3306 _page_sizes[0] = _large_page_size;
3307 _page_sizes[1] = default_page_size;
3308 _page_sizes[2] = 0;
3309 }
3310
3311 return _large_page_size;
3312 }
3313
3314 bool os::Linux::setup_large_page_type(size_t page_size) {
3315 if (FLAG_IS_DEFAULT(UseHugeTLBFS) &&
3316 FLAG_IS_DEFAULT(UseSHM) &&
3317 FLAG_IS_DEFAULT(UseTransparentHugePages)) {
3318
3319 // The type of large pages has not been specified by the user.
3320
3321 // Try UseHugeTLBFS and then UseSHM.
3322 UseHugeTLBFS = UseSHM = true;
3323
3324 // Don't try UseTransparentHugePages since there are known
3325 // performance issues with it turned on. This might change in the future.
3326 UseTransparentHugePages = false;
3327 }
3328
3329 if (UseTransparentHugePages) {
3330 bool warn_on_failure = !FLAG_IS_DEFAULT(UseTransparentHugePages);
3331 if (transparent_huge_pages_sanity_check(warn_on_failure, page_size)) {
3332 UseHugeTLBFS = false;
3333 UseSHM = false;
3334 return true;
3335 }
3336 UseTransparentHugePages = false;
3337 }
3338
3339 if (UseHugeTLBFS) {
3340 bool warn_on_failure = !FLAG_IS_DEFAULT(UseHugeTLBFS);
3341 if (hugetlbfs_sanity_check(warn_on_failure, page_size)) {
3342 UseSHM = false;
3343 return true;
3344 }
3345 UseHugeTLBFS = false;
3346 }
3347
3348 return UseSHM;
3349 }
3350
3351 void os::large_page_init() {
3352 if (!UseLargePages &&
3353 !UseTransparentHugePages &&
3354 !UseHugeTLBFS &&
3355 !UseSHM) {
3356 // Not using large pages.
3357 return;
3358 }
3359
3360 if (!FLAG_IS_DEFAULT(UseLargePages) && !UseLargePages) {
3361 // The user explicitly turned off large pages.
3362 // Ignore the rest of the large pages flags.
3363 UseTransparentHugePages = false;
3364 UseHugeTLBFS = false;
3365 UseSHM = false;
3366 return;
3367 }
3368
3369 size_t large_page_size = Linux::setup_large_page_size();
3370 UseLargePages = Linux::setup_large_page_type(large_page_size);
3371
3372 set_coredump_filter();
3373 }
3374
3375 #ifndef SHM_HUGETLB
3376 #define SHM_HUGETLB 04000
3377 #endif
3378
3379 char* os::Linux::reserve_memory_special_shm(size_t bytes, size_t alignment, char* req_addr, bool exec) {
3380 // "exec" is passed in but not used. Creating the shared image for
3381 // the code cache doesn't have an SHM_X executable permission to check.
3382 assert(UseLargePages && UseSHM, "only for SHM large pages");
3383 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address");
3384
3385 if (!is_size_aligned(bytes, os::large_page_size()) || alignment > os::large_page_size()) {
3386 return NULL; // Fallback to small pages.
3387 }
3388
3389 key_t key = IPC_PRIVATE;
3390 char *addr;
3391
3392 bool warn_on_failure = UseLargePages &&
3393 (!FLAG_IS_DEFAULT(UseLargePages) ||
3394 !FLAG_IS_DEFAULT(UseSHM) ||
3395 !FLAG_IS_DEFAULT(LargePageSizeInBytes)
3396 );
3397 char msg[128];
3398
3399 // Create a large shared memory region to attach to based on size.
3400 // Currently, size is the total size of the heap
3401 int shmid = shmget(key, bytes, SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W);
3402 if (shmid == -1) {
3403 // Possible reasons for shmget failure:
3404 // 1. shmmax is too small for Java heap.
3405 // > check shmmax value: cat /proc/sys/kernel/shmmax
3406 // > increase shmmax value: echo "0xffffffff" > /proc/sys/kernel/shmmax
3407 // 2. not enough large page memory.
3408 // > check available large pages: cat /proc/meminfo
3409 // > increase amount of large pages:
3410 // echo new_value > /proc/sys/vm/nr_hugepages
3411 // Note 1: different Linux may use different name for this property,
3412 // e.g. on Redhat AS-3 it is "hugetlb_pool".
3413 // Note 2: it's possible there's enough physical memory available but
3414 // they are so fragmented after a long run that they can't
3415 // coalesce into large pages. Try to reserve large pages when
3416 // the system is still "fresh".
3417 if (warn_on_failure) {
3418 jio_snprintf(msg, sizeof(msg), "Failed to reserve shared memory (errno = %d).", errno);
3419 warning(msg);
3420 }
3421 return NULL;
3422 }
3423
3424 // attach to the region
3425 addr = (char*)shmat(shmid, req_addr, 0);
3426 int err = errno;
3427
3428 // Remove shmid. If shmat() is successful, the actual shared memory segment
3429 // will be deleted when it's detached by shmdt() or when the process
3430 // terminates. If shmat() is not successful this will remove the shared
3431 // segment immediately.
3432 shmctl(shmid, IPC_RMID, NULL);
3433
3434 if ((intptr_t)addr == -1) {
3435 if (warn_on_failure) {
3436 jio_snprintf(msg, sizeof(msg), "Failed to attach shared memory (errno = %d).", err);
3437 warning(msg);
3438 }
3439 return NULL;
3440 }
3441
3442 return addr;
3443 }
3444
3445 static void warn_on_large_pages_failure(char* req_addr, size_t bytes, int error) {
3446 assert(error == ENOMEM, "Only expect to fail if no memory is available");
3447
3448 bool warn_on_failure = UseLargePages &&
3449 (!FLAG_IS_DEFAULT(UseLargePages) ||
3450 !FLAG_IS_DEFAULT(UseHugeTLBFS) ||
3451 !FLAG_IS_DEFAULT(LargePageSizeInBytes));
3452
3453 if (warn_on_failure) {
3454 char msg[128];
3455 jio_snprintf(msg, sizeof(msg), "Failed to reserve large pages memory req_addr: "
3456 PTR_FORMAT " bytes: " SIZE_FORMAT " (errno = %d).", req_addr, bytes, error);
3457 warning(msg);
3458 }
3459 }
3460
3461 char* os::Linux::reserve_memory_special_huge_tlbfs_only(size_t bytes, char* req_addr, bool exec) {
3462 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages");
3463 assert(is_size_aligned(bytes, os::large_page_size()), "Unaligned size");
3464 assert(is_ptr_aligned(req_addr, os::large_page_size()), "Unaligned address");
3465
3466 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
3467 char* addr = (char*)::mmap(req_addr, bytes, prot,
3468 MAP_PRIVATE|MAP_ANONYMOUS|MAP_HUGETLB,
3469 -1, 0);
3470
3471 if (addr == MAP_FAILED) {
3472 warn_on_large_pages_failure(req_addr, bytes, errno);
3473 return NULL;
3474 }
3475
3476 assert(is_ptr_aligned(addr, os::large_page_size()), "Must be");
3477
3478 return addr;
3479 }
3480
3481 char* os::Linux::reserve_memory_special_huge_tlbfs_mixed(size_t bytes, size_t alignment, char* req_addr, bool exec) {
3482 size_t large_page_size = os::large_page_size();
3483
3484 assert(bytes >= large_page_size, "Shouldn't allocate large pages for small sizes");
3485
3486 // Allocate small pages.
3487
3488 char* start;
3489 if (req_addr != NULL) {
3490 assert(is_ptr_aligned(req_addr, alignment), "Must be");
3491 assert(is_size_aligned(bytes, alignment), "Must be");
3492 start = os::reserve_memory(bytes, req_addr);
3493 assert(start == NULL || start == req_addr, "Must be");
3494 } else {
3495 start = os::reserve_memory_aligned(bytes, alignment);
3496 }
3497
3498 if (start == NULL) {
3499 return NULL;
3500 }
3501
3502 assert(is_ptr_aligned(start, alignment), "Must be");
3503
3504 // os::reserve_memory_special will record this memory area.
3505 // Need to release it here to prevent overlapping reservations.
3506 MemTracker::record_virtual_memory_release((address)start, bytes);
3507
3508 char* end = start + bytes;
3509
3510 // Find the regions of the allocated chunk that can be promoted to large pages.
3511 char* lp_start = (char*)align_ptr_up(start, large_page_size);
3512 char* lp_end = (char*)align_ptr_down(end, large_page_size);
3513
3514 size_t lp_bytes = lp_end - lp_start;
3515
3516 assert(is_size_aligned(lp_bytes, large_page_size), "Must be");
3517
3518 if (lp_bytes == 0) {
3519 // The mapped region doesn't even span the start and the end of a large page.
3520 // Fall back to allocate a non-special area.
3521 ::munmap(start, end - start);
3522 return NULL;
3523 }
3524
3525 int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
3526
3527
3528 void* result;
3529
3530 if (start != lp_start) {
3531 result = ::mmap(start, lp_start - start, prot,
3532 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED,
3533 -1, 0);
3534 if (result == MAP_FAILED) {
3535 ::munmap(lp_start, end - lp_start);
3536 return NULL;
3537 }
3538 }
3539
3540 result = ::mmap(lp_start, lp_bytes, prot,
3541 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED|MAP_HUGETLB,
3542 -1, 0);
3543 if (result == MAP_FAILED) {
3544 warn_on_large_pages_failure(req_addr, bytes, errno);
3545 // If the mmap above fails, the large pages region will be unmapped and we
3546 // have regions before and after with small pages. Release these regions.
3547 //
3548 // | mapped | unmapped | mapped |
3549 // ^ ^ ^ ^
3550 // start lp_start lp_end end
3551 //
3552 ::munmap(start, lp_start - start);
3553 ::munmap(lp_end, end - lp_end);
3554 return NULL;
3555 }
3556
3557 if (lp_end != end) {
3558 result = ::mmap(lp_end, end - lp_end, prot,
3559 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED,
3560 -1, 0);
3561 if (result == MAP_FAILED) {
3562 ::munmap(start, lp_end - start);
3563 return NULL;
3564 }
3565 }
3566
3567 return start;
3568 }
3569
3570 char* os::Linux::reserve_memory_special_huge_tlbfs(size_t bytes, size_t alignment, char* req_addr, bool exec) {
3571 assert(UseLargePages && UseHugeTLBFS, "only for Huge TLBFS large pages");
3572 assert(is_ptr_aligned(req_addr, alignment), "Must be");
3573 assert(is_power_of_2(alignment), "Must be");
3574 assert(is_power_of_2(os::large_page_size()), "Must be");
3575 assert(bytes >= os::large_page_size(), "Shouldn't allocate large pages for small sizes");
3576
3577 if (is_size_aligned(bytes, os::large_page_size()) && alignment <= os::large_page_size()) {
3578 return reserve_memory_special_huge_tlbfs_only(bytes, req_addr, exec);
3579 } else {
3580 return reserve_memory_special_huge_tlbfs_mixed(bytes, alignment, req_addr, exec);
3581 }
3582 }
3583
3584 char* os::reserve_memory_special(size_t bytes, size_t alignment, char* req_addr, bool exec) {
3585 assert(UseLargePages, "only for large pages");
3586
3587 char* addr;
3588 if (UseSHM) {
3589 addr = os::Linux::reserve_memory_special_shm(bytes, alignment, req_addr, exec);
3590 } else {
3591 assert(UseHugeTLBFS, "must be");
3592 addr = os::Linux::reserve_memory_special_huge_tlbfs(bytes, alignment, req_addr, exec);
3593 }
3594
3595 if (addr != NULL) {
3596 if (UseNUMAInterleaving) {
3597 numa_make_global(addr, bytes);
3598 }
3599
3600 // The memory is committed
3601 MemTracker::record_virtual_memory_reserve_and_commit((address)addr, bytes, mtNone, CALLER_PC);
3602 }
3603
3604 return addr;
3605 }
3606
3607 bool os::Linux::release_memory_special_shm(char* base, size_t bytes) {
3608 // detaching the SHM segment will also delete it, see reserve_memory_special_shm()
3609 return shmdt(base) == 0;
3610 }
3611
3612 bool os::Linux::release_memory_special_huge_tlbfs(char* base, size_t bytes) {
3613 return pd_release_memory(base, bytes);
3614 }
3615
3616 bool os::release_memory_special(char* base, size_t bytes) {
3617 assert(UseLargePages, "only for large pages");
3618
3619 MemTracker::Tracker tkr = MemTracker::get_virtual_memory_release_tracker();
3620
3621 bool res;
3622 if (UseSHM) {
3623 res = os::Linux::release_memory_special_shm(base, bytes);
3624 } else {
3625 assert(UseHugeTLBFS, "must be");
3626 res = os::Linux::release_memory_special_huge_tlbfs(base, bytes);
3627 }
3628
3629 if (res) {
3630 tkr.record((address)base, bytes);
3631 } else {
3632 tkr.discard();
3633 }
3634
3635 return res;
3636 }
3637
3638 size_t os::large_page_size() {
3639 return _large_page_size;
3640 }
3641
3642 // With SysV SHM the entire memory region must be allocated as shared
3643 // memory.
3644 // HugeTLBFS allows application to commit large page memory on demand.
3645 // However, when committing memory with HugeTLBFS fails, the region
3646 // that was supposed to be committed will lose the old reservation
3647 // and allow other threads to steal that memory region. Because of this
3648 // behavior we can't commit HugeTLBFS memory.
3649 bool os::can_commit_large_page_memory() {
3650 return UseTransparentHugePages;
3651 }
3652
3653 bool os::can_execute_large_page_memory() {
3654 return UseTransparentHugePages || UseHugeTLBFS;
3655 }
3656
3657 // Reserve memory at an arbitrary address, only if that area is
3658 // available (and not reserved for something else).
3659
3660 char* os::pd_attempt_reserve_memory_at(size_t bytes, char* requested_addr) {
3661 const int max_tries = 10;
3662 char* base[max_tries];
3663 size_t size[max_tries];
3664 const size_t gap = 0x000000;
3665
3666 // Assert only that the size is a multiple of the page size, since
3667 // that's all that mmap requires, and since that's all we really know
3668 // about at this low abstraction level. If we need higher alignment,
3669 // we can either pass an alignment to this method or verify alignment
3670 // in one of the methods further up the call chain. See bug 5044738.
3671 assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block");
3672
3673 // Repeatedly allocate blocks until the block is allocated at the
3674 // right spot. Give up after max_tries. Note that reserve_memory() will
3675 // automatically update _highest_vm_reserved_address if the call is
3676 // successful. The variable tracks the highest memory address every reserved
3677 // by JVM. It is used to detect heap-stack collision if running with
3678 // fixed-stack LinuxThreads. Because here we may attempt to reserve more
3679 // space than needed, it could confuse the collision detecting code. To
3680 // solve the problem, save current _highest_vm_reserved_address and
3681 // calculate the correct value before return.
3682 address old_highest = _highest_vm_reserved_address;
3683
3684 // Linux mmap allows caller to pass an address as hint; give it a try first,
3685 // if kernel honors the hint then we can return immediately.
3686 char * addr = anon_mmap(requested_addr, bytes, false);
3687 if (addr == requested_addr) {
3688 return requested_addr;
3689 }
3690
3691 if (addr != NULL) {
3692 // mmap() is successful but it fails to reserve at the requested address
3693 anon_munmap(addr, bytes);
3694 }
3695
3696 int i;
3697 for (i = 0; i < max_tries; ++i) {
3698 base[i] = reserve_memory(bytes);
3699
3700 if (base[i] != NULL) {
3701 // Is this the block we wanted?
3702 if (base[i] == requested_addr) {
3703 size[i] = bytes;
3704 break;
3705 }
3706
3707 // Does this overlap the block we wanted? Give back the overlapped
3708 // parts and try again.
3709
3710 size_t top_overlap = requested_addr + (bytes + gap) - base[i];
3711 if (top_overlap >= 0 && top_overlap < bytes) {
3712 unmap_memory(base[i], top_overlap);
3713 base[i] += top_overlap;
3714 size[i] = bytes - top_overlap;
3715 } else {
3716 size_t bottom_overlap = base[i] + bytes - requested_addr;
3717 if (bottom_overlap >= 0 && bottom_overlap < bytes) {
3718 unmap_memory(requested_addr, bottom_overlap);
3719 size[i] = bytes - bottom_overlap;
3720 } else {
3721 size[i] = bytes;
3722 }
3723 }
3724 }
3725 }
3726
3727 // Give back the unused reserved pieces.
3728
3729 for (int j = 0; j < i; ++j) {
3730 if (base[j] != NULL) {
3731 unmap_memory(base[j], size[j]);
3732 }
3733 }
3734
3735 if (i < max_tries) {
3736 _highest_vm_reserved_address = MAX2(old_highest, (address)requested_addr + bytes);
3737 return requested_addr;
3738 } else {
3739 _highest_vm_reserved_address = old_highest;
3740 return NULL;
3741 }
3742 }
3743
3744 size_t os::read(int fd, void *buf, unsigned int nBytes) {
3745 return ::read(fd, buf, nBytes);
3746 }
3747
3748 //
3749 // Short sleep, direct OS call.
3750 //
3751 // Note: certain versions of Linux CFS scheduler (since 2.6.23) do not guarantee
3752 // sched_yield(2) will actually give up the CPU:
3753 //
3754 // * Alone on this pariticular CPU, keeps running.
3755 // * Before the introduction of "skip_buddy" with "compat_yield" disabled
3756 // (pre 2.6.39).
3757 //
3758 // So calling this with 0 is an alternative.
3759 //
3760 void os::naked_short_sleep(jlong ms) {
3761 struct timespec req;
3762
3763 assert(ms < 1000, "Un-interruptable sleep, short time use only");
3764 req.tv_sec = 0;
3765 if (ms > 0) {
3766 req.tv_nsec = (ms % 1000) * 1000000;
3767 }
3768 else {
3769 req.tv_nsec = 1;
3770 }
3771
3772 nanosleep(&req, NULL);
3773
3774 return;
3775 }
3776
3777 // Sleep forever; naked call to OS-specific sleep; use with CAUTION
3778 void os::infinite_sleep() {
3779 while (true) { // sleep forever ...
3780 ::sleep(100); // ... 100 seconds at a time
3781 }
3782 }
3783
3784 // Used to convert frequent JVM_Yield() to nops
3785 bool os::dont_yield() {
3786 return DontYieldALot;
3787 }
3788
3789 void os::yield() {
3790 sched_yield();
3791 }
3792
3793 os::YieldResult os::NakedYield() { sched_yield(); return os::YIELD_UNKNOWN ;}
3794
3795 void os::yield_all() {
3796 // Yields to all threads, including threads with lower priorities
3797 // Threads on Linux are all with same priority. The Solaris style
3798 // os::yield_all() with nanosleep(1ms) is not necessary.
3799 sched_yield();
3800 }
3801
3802 ////////////////////////////////////////////////////////////////////////////////
3803 // thread priority support
3804
3805 // Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER
3806 // only supports dynamic priority, static priority must be zero. For real-time
3807 // applications, Linux supports SCHED_RR which allows static priority (1-99).
3808 // However, for large multi-threaded applications, SCHED_RR is not only slower
3809 // than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out
3810 // of 5 runs - Sep 2005).
3811 //
3812 // The following code actually changes the niceness of kernel-thread/LWP. It
3813 // has an assumption that setpriority() only modifies one kernel-thread/LWP,
3814 // not the entire user process, and user level threads are 1:1 mapped to kernel
3815 // threads. It has always been the case, but could change in the future. For
3816 // this reason, the code should not be used as default (ThreadPriorityPolicy=0).
3817 // It is only used when ThreadPriorityPolicy=1 and requires root privilege.
3818
3819 int os::java_to_os_priority[CriticalPriority + 1] = {
3820 19, // 0 Entry should never be used
3821
3822 4, // 1 MinPriority
3823 3, // 2
3824 2, // 3
3825
3826 1, // 4
3827 0, // 5 NormPriority
3828 -1, // 6
3829
3830 -2, // 7
3831 -3, // 8
3832 -4, // 9 NearMaxPriority
3833
3834 -5, // 10 MaxPriority
3835
3836 -5 // 11 CriticalPriority
3837 };
3838
3839 static int prio_init() {
3840 if (ThreadPriorityPolicy == 1) {
3841 // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1
3842 // if effective uid is not root. Perhaps, a more elegant way of doing
3843 // this is to test CAP_SYS_NICE capability, but that will require libcap.so
3844 if (geteuid() != 0) {
3845 if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) {
3846 warning("-XX:ThreadPriorityPolicy requires root privilege on Linux");
3847 }
3848 ThreadPriorityPolicy = 0;
3849 }
3850 }
3851 if (UseCriticalJavaThreadPriority) {
3852 os::java_to_os_priority[MaxPriority] = os::java_to_os_priority[CriticalPriority];
3853 }
3854 return 0;
3855 }
3856
3857 OSReturn os::set_native_priority(Thread* thread, int newpri) {
3858 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) return OS_OK;
3859
3860 int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri);
3861 return (ret == 0) ? OS_OK : OS_ERR;
3862 }
3863
3864 OSReturn os::get_native_priority(const Thread* const thread, int *priority_ptr) {
3865 if ( !UseThreadPriorities || ThreadPriorityPolicy == 0 ) {
3866 *priority_ptr = java_to_os_priority[NormPriority];
3867 return OS_OK;
3868 }
3869
3870 errno = 0;
3871 *priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id());
3872 return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR);
3873 }
3874
3875 // Hint to the underlying OS that a task switch would not be good.
3876 // Void return because it's a hint and can fail.
3877 void os::hint_no_preempt() {}
3878
3879 ////////////////////////////////////////////////////////////////////////////////
3880 // suspend/resume support
3881
3882 // the low-level signal-based suspend/resume support is a remnant from the
3883 // old VM-suspension that used to be for java-suspension, safepoints etc,
3884 // within hotspot. Now there is a single use-case for this:
3885 // - calling get_thread_pc() on the VMThread by the flat-profiler task
3886 // that runs in the watcher thread.
3887 // The remaining code is greatly simplified from the more general suspension
3888 // code that used to be used.
3889 //
3890 // The protocol is quite simple:
3891 // - suspend:
3892 // - sends a signal to the target thread
3893 // - polls the suspend state of the osthread using a yield loop
3894 // - target thread signal handler (SR_handler) sets suspend state
3895 // and blocks in sigsuspend until continued
3896 // - resume:
3897 // - sets target osthread state to continue
3898 // - sends signal to end the sigsuspend loop in the SR_handler
3899 //
3900 // Note that the SR_lock plays no role in this suspend/resume protocol.
3901 //
3902
3903 static void resume_clear_context(OSThread *osthread) {
3904 osthread->set_ucontext(NULL);
3905 osthread->set_siginfo(NULL);
3906 }
3907
3908 static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo, ucontext_t* context) {
3909 osthread->set_ucontext(context);
3910 osthread->set_siginfo(siginfo);
3911 }
3912
3913 //
3914 // Handler function invoked when a thread's execution is suspended or
3915 // resumed. We have to be careful that only async-safe functions are
3916 // called here (Note: most pthread functions are not async safe and
3917 // should be avoided.)
3918 //
3919 // Note: sigwait() is a more natural fit than sigsuspend() from an
3920 // interface point of view, but sigwait() prevents the signal hander
3921 // from being run. libpthread would get very confused by not having
3922 // its signal handlers run and prevents sigwait()'s use with the
3923 // mutex granting granting signal.
3924 //
3925 // Currently only ever called on the VMThread and JavaThreads (PC sampling)
3926 //
3927 static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) {
3928 // Save and restore errno to avoid confusing native code with EINTR
3929 // after sigsuspend.
3930 int old_errno = errno;
3931
3932 Thread* thread = Thread::current();
3933 OSThread* osthread = thread->osthread();
3934 assert(thread->is_VM_thread() || thread->is_Java_thread(), "Must be VMThread or JavaThread");
3935
3936 os::SuspendResume::State current = osthread->sr.state();
3937 if (current == os::SuspendResume::SR_SUSPEND_REQUEST) {
3938 suspend_save_context(osthread, siginfo, context);
3939
3940 // attempt to switch the state, we assume we had a SUSPEND_REQUEST
3941 os::SuspendResume::State state = osthread->sr.suspended();
3942 if (state == os::SuspendResume::SR_SUSPENDED) {
3943 sigset_t suspend_set; // signals for sigsuspend()
3944
3945 // get current set of blocked signals and unblock resume signal
3946 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set);
3947 sigdelset(&suspend_set, SR_signum);
3948
3949 sr_semaphore.signal();
3950 // wait here until we are resumed
3951 while (1) {
3952 sigsuspend(&suspend_set);
3953
3954 os::SuspendResume::State result = osthread->sr.running();
3955 if (result == os::SuspendResume::SR_RUNNING) {
3956 sr_semaphore.signal();
3957 break;
3958 }
3959 }
3960
3961 } else if (state == os::SuspendResume::SR_RUNNING) {
3962 // request was cancelled, continue
3963 } else {
3964 ShouldNotReachHere();
3965 }
3966
3967 resume_clear_context(osthread);
3968 } else if (current == os::SuspendResume::SR_RUNNING) {
3969 // request was cancelled, continue
3970 } else if (current == os::SuspendResume::SR_WAKEUP_REQUEST) {
3971 // ignore
3972 } else {
3973 // ignore
3974 }
3975
3976 errno = old_errno;
3977 }
3978
3979
3980 static int SR_initialize() {
3981 struct sigaction act;
3982 char *s;
3983 /* Get signal number to use for suspend/resume */
3984 if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) {
3985 int sig = ::strtol(s, 0, 10);
3986 if (sig > 0 || sig < _NSIG) {
3987 SR_signum = sig;
3988 }
3989 }
3990
3991 assert(SR_signum > SIGSEGV && SR_signum > SIGBUS,
3992 "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769");
3993
3994 sigemptyset(&SR_sigset);
3995 sigaddset(&SR_sigset, SR_signum);
3996
3997 /* Set up signal handler for suspend/resume */
3998 act.sa_flags = SA_RESTART|SA_SIGINFO;
3999 act.sa_handler = (void (*)(int)) SR_handler;
4000
4001 // SR_signum is blocked by default.
4002 // 4528190 - We also need to block pthread restart signal (32 on all
4003 // supported Linux platforms). Note that LinuxThreads need to block
4004 // this signal for all threads to work properly. So we don't have
4005 // to use hard-coded signal number when setting up the mask.
4006 pthread_sigmask(SIG_BLOCK, NULL, &act.sa_mask);
4007
4008 if (sigaction(SR_signum, &act, 0) == -1) {
4009 return -1;
4010 }
4011
4012 // Save signal flag
4013 os::Linux::set_our_sigflags(SR_signum, act.sa_flags);
4014 return 0;
4015 }
4016
4017 static int sr_notify(OSThread* osthread) {
4018 int status = pthread_kill(osthread->pthread_id(), SR_signum);
4019 assert_status(status == 0, status, "pthread_kill");
4020 return status;
4021 }
4022
4023 // "Randomly" selected value for how long we want to spin
4024 // before bailing out on suspending a thread, also how often
4025 // we send a signal to a thread we want to resume
4026 static const int RANDOMLY_LARGE_INTEGER = 1000000;
4027 static const int RANDOMLY_LARGE_INTEGER2 = 100;
4028
4029 // returns true on success and false on error - really an error is fatal
4030 // but this seems the normal response to library errors
4031 static bool do_suspend(OSThread* osthread) {
4032 assert(osthread->sr.is_running(), "thread should be running");
4033 assert(!sr_semaphore.trywait(), "semaphore has invalid state");
4034
4035 // mark as suspended and send signal
4036 if (osthread->sr.request_suspend() != os::SuspendResume::SR_SUSPEND_REQUEST) {
4037 // failed to switch, state wasn't running?
4038 ShouldNotReachHere();
4039 return false;
4040 }
4041
4042 if (sr_notify(osthread) != 0) {
4043 ShouldNotReachHere();
4044 }
4045
4046 // managed to send the signal and switch to SUSPEND_REQUEST, now wait for SUSPENDED
4047 while (true) {
4048 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) {
4049 break;
4050 } else {
4051 // timeout
4052 os::SuspendResume::State cancelled = osthread->sr.cancel_suspend();
4053 if (cancelled == os::SuspendResume::SR_RUNNING) {
4054 return false;
4055 } else if (cancelled == os::SuspendResume::SR_SUSPENDED) {
4056 // make sure that we consume the signal on the semaphore as well
4057 sr_semaphore.wait();
4058 break;
4059 } else {
4060 ShouldNotReachHere();
4061 return false;
4062 }
4063 }
4064 }
4065
4066 guarantee(osthread->sr.is_suspended(), "Must be suspended");
4067 return true;
4068 }
4069
4070 static void do_resume(OSThread* osthread) {
4071 assert(osthread->sr.is_suspended(), "thread should be suspended");
4072 assert(!sr_semaphore.trywait(), "invalid semaphore state");
4073
4074 if (osthread->sr.request_wakeup() != os::SuspendResume::SR_WAKEUP_REQUEST) {
4075 // failed to switch to WAKEUP_REQUEST
4076 ShouldNotReachHere();
4077 return;
4078 }
4079
4080 while (true) {
4081 if (sr_notify(osthread) == 0) {
4082 if (sr_semaphore.timedwait(0, 2 * NANOSECS_PER_MILLISEC)) {
4083 if (osthread->sr.is_running()) {
4084 return;
4085 }
4086 }
4087 } else {
4088 ShouldNotReachHere();
4089 }
4090 }
4091
4092 guarantee(osthread->sr.is_running(), "Must be running!");
4093 }
4094
4095 ///////////////////////////////////////////////////////////////////////////////////
4096 // signal handling (except suspend/resume)
4097
4098 // This routine may be used by user applications as a "hook" to catch signals.
4099 // The user-defined signal handler must pass unrecognized signals to this
4100 // routine, and if it returns true (non-zero), then the signal handler must
4101 // return immediately. If the flag "abort_if_unrecognized" is true, then this
4102 // routine will never retun false (zero), but instead will execute a VM panic
4103 // routine kill the process.
4104 //
4105 // If this routine returns false, it is OK to call it again. This allows
4106 // the user-defined signal handler to perform checks either before or after
4107 // the VM performs its own checks. Naturally, the user code would be making
4108 // a serious error if it tried to handle an exception (such as a null check
4109 // or breakpoint) that the VM was generating for its own correct operation.
4110 //
4111 // This routine may recognize any of the following kinds of signals:
4112 // SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1.
4113 // It should be consulted by handlers for any of those signals.
4114 //
4115 // The caller of this routine must pass in the three arguments supplied
4116 // to the function referred to in the "sa_sigaction" (not the "sa_handler")
4117 // field of the structure passed to sigaction(). This routine assumes that
4118 // the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART.
4119 //
4120 // Note that the VM will print warnings if it detects conflicting signal
4121 // handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers".
4122 //
4123 extern "C" JNIEXPORT int
4124 JVM_handle_linux_signal(int signo, siginfo_t* siginfo,
4125 void* ucontext, int abort_if_unrecognized);
4126
4127 void signalHandler(int sig, siginfo_t* info, void* uc) {
4128 assert(info != NULL && uc != NULL, "it must be old kernel");
4129 int orig_errno = errno; // Preserve errno value over signal handler.
4130 JVM_handle_linux_signal(sig, info, uc, true);
4131 errno = orig_errno;
4132 }
4133
4134
4135 // This boolean allows users to forward their own non-matching signals
4136 // to JVM_handle_linux_signal, harmlessly.
4137 bool os::Linux::signal_handlers_are_installed = false;
4138
4139 // For signal-chaining
4140 struct sigaction os::Linux::sigact[MAXSIGNUM];
4141 unsigned int os::Linux::sigs = 0;
4142 bool os::Linux::libjsig_is_loaded = false;
4143 typedef struct sigaction *(*get_signal_t)(int);
4144 get_signal_t os::Linux::get_signal_action = NULL;
4145
4146 struct sigaction* os::Linux::get_chained_signal_action(int sig) {
4147 struct sigaction *actp = NULL;
4148
4149 if (libjsig_is_loaded) {
4150 // Retrieve the old signal handler from libjsig
4151 actp = (*get_signal_action)(sig);
4152 }
4153 if (actp == NULL) {
4154 // Retrieve the preinstalled signal handler from jvm
4155 actp = get_preinstalled_handler(sig);
4156 }
4157
4158 return actp;
4159 }
4160
4161 static bool call_chained_handler(struct sigaction *actp, int sig,
4162 siginfo_t *siginfo, void *context) {
4163 // Call the old signal handler
4164 if (actp->sa_handler == SIG_DFL) {
4165 // It's more reasonable to let jvm treat it as an unexpected exception
4166 // instead of taking the default action.
4167 return false;
4168 } else if (actp->sa_handler != SIG_IGN) {
4169 if ((actp->sa_flags & SA_NODEFER) == 0) {
4170 // automaticlly block the signal
4171 sigaddset(&(actp->sa_mask), sig);
4172 }
4173
4174 sa_handler_t hand;
4175 sa_sigaction_t sa;
4176 bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO) != 0;
4177 // retrieve the chained handler
4178 if (siginfo_flag_set) {
4179 sa = actp->sa_sigaction;
4180 } else {
4181 hand = actp->sa_handler;
4182 }
4183
4184 if ((actp->sa_flags & SA_RESETHAND) != 0) {
4185 actp->sa_handler = SIG_DFL;
4186 }
4187
4188 // try to honor the signal mask
4189 sigset_t oset;
4190 pthread_sigmask(SIG_SETMASK, &(actp->sa_mask), &oset);
4191
4192 // call into the chained handler
4193 if (siginfo_flag_set) {
4194 (*sa)(sig, siginfo, context);
4195 } else {
4196 (*hand)(sig);
4197 }
4198
4199 // restore the signal mask
4200 pthread_sigmask(SIG_SETMASK, &oset, 0);
4201 }
4202 // Tell jvm's signal handler the signal is taken care of.
4203 return true;
4204 }
4205
4206 bool os::Linux::chained_handler(int sig, siginfo_t* siginfo, void* context) {
4207 bool chained = false;
4208 // signal-chaining
4209 if (UseSignalChaining) {
4210 struct sigaction *actp = get_chained_signal_action(sig);
4211 if (actp != NULL) {
4212 chained = call_chained_handler(actp, sig, siginfo, context);
4213 }
4214 }
4215 return chained;
4216 }
4217
4218 struct sigaction* os::Linux::get_preinstalled_handler(int sig) {
4219 if ((( (unsigned int)1 << sig ) & sigs) != 0) {
4220 return &sigact[sig];
4221 }
4222 return NULL;
4223 }
4224
4225 void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) {
4226 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4227 sigact[sig] = oldAct;
4228 sigs |= (unsigned int)1 << sig;
4229 }
4230
4231 // for diagnostic
4232 int os::Linux::sigflags[MAXSIGNUM];
4233
4234 int os::Linux::get_our_sigflags(int sig) {
4235 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4236 return sigflags[sig];
4237 }
4238
4239 void os::Linux::set_our_sigflags(int sig, int flags) {
4240 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4241 sigflags[sig] = flags;
4242 }
4243
4244 void os::Linux::set_signal_handler(int sig, bool set_installed) {
4245 // Check for overwrite.
4246 struct sigaction oldAct;
4247 sigaction(sig, (struct sigaction*)NULL, &oldAct);
4248
4249 void* oldhand = oldAct.sa_sigaction
4250 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction)
4251 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler);
4252 if (oldhand != CAST_FROM_FN_PTR(void*, SIG_DFL) &&
4253 oldhand != CAST_FROM_FN_PTR(void*, SIG_IGN) &&
4254 oldhand != CAST_FROM_FN_PTR(void*, (sa_sigaction_t)signalHandler)) {
4255 if (AllowUserSignalHandlers || !set_installed) {
4256 // Do not overwrite; user takes responsibility to forward to us.
4257 return;
4258 } else if (UseSignalChaining) {
4259 // save the old handler in jvm
4260 save_preinstalled_handler(sig, oldAct);
4261 // libjsig also interposes the sigaction() call below and saves the
4262 // old sigaction on it own.
4263 } else {
4264 fatal(err_msg("Encountered unexpected pre-existing sigaction handler "
4265 "%#lx for signal %d.", (long)oldhand, sig));
4266 }
4267 }
4268
4269 struct sigaction sigAct;
4270 sigfillset(&(sigAct.sa_mask));
4271 sigAct.sa_handler = SIG_DFL;
4272 if (!set_installed) {
4273 sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
4274 } else {
4275 sigAct.sa_sigaction = signalHandler;
4276 sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
4277 }
4278 // Save flags, which are set by ours
4279 assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
4280 sigflags[sig] = sigAct.sa_flags;
4281
4282 int ret = sigaction(sig, &sigAct, &oldAct);
4283 assert(ret == 0, "check");
4284
4285 void* oldhand2 = oldAct.sa_sigaction
4286 ? CAST_FROM_FN_PTR(void*, oldAct.sa_sigaction)
4287 : CAST_FROM_FN_PTR(void*, oldAct.sa_handler);
4288 assert(oldhand2 == oldhand, "no concurrent signal handler installation");
4289 }
4290
4291 // install signal handlers for signals that HotSpot needs to
4292 // handle in order to support Java-level exception handling.
4293
4294 void os::Linux::install_signal_handlers() {
4295 if (!signal_handlers_are_installed) {
4296 signal_handlers_are_installed = true;
4297
4298 // signal-chaining
4299 typedef void (*signal_setting_t)();
4300 signal_setting_t begin_signal_setting = NULL;
4301 signal_setting_t end_signal_setting = NULL;
4302 begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
4303 dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting"));
4304 if (begin_signal_setting != NULL) {
4305 end_signal_setting = CAST_TO_FN_PTR(signal_setting_t,
4306 dlsym(RTLD_DEFAULT, "JVM_end_signal_setting"));
4307 get_signal_action = CAST_TO_FN_PTR(get_signal_t,
4308 dlsym(RTLD_DEFAULT, "JVM_get_signal_action"));
4309 libjsig_is_loaded = true;
4310 assert(UseSignalChaining, "should enable signal-chaining");
4311 }
4312 if (libjsig_is_loaded) {
4313 // Tell libjsig jvm is setting signal handlers
4314 (*begin_signal_setting)();
4315 }
4316
4317 set_signal_handler(SIGSEGV, true);
4318 set_signal_handler(SIGPIPE, true);
4319 set_signal_handler(SIGBUS, true);
4320 set_signal_handler(SIGILL, true);
4321 set_signal_handler(SIGFPE, true);
4322 #if defined(PPC64)
4323 set_signal_handler(SIGTRAP, true);
4324 #endif
4325 set_signal_handler(SIGXFSZ, true);
4326
4327 if (libjsig_is_loaded) {
4328 // Tell libjsig jvm finishes setting signal handlers
4329 (*end_signal_setting)();
4330 }
4331
4332 // We don't activate signal checker if libjsig is in place, we trust ourselves
4333 // and if UserSignalHandler is installed all bets are off.
4334 // Log that signal checking is off only if -verbose:jni is specified.
4335 if (CheckJNICalls) {
4336 if (libjsig_is_loaded) {
4337 if (PrintJNIResolving) {
4338 tty->print_cr("Info: libjsig is activated, all active signal checking is disabled");
4339 }
4340 check_signals = false;
4341 }
4342 if (AllowUserSignalHandlers) {
4343 if (PrintJNIResolving) {
4344 tty->print_cr("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled");
4345 }
4346 check_signals = false;
4347 }
4348 }
4349 }
4350 }
4351
4352 // This is the fastest way to get thread cpu time on Linux.
4353 // Returns cpu time (user+sys) for any thread, not only for current.
4354 // POSIX compliant clocks are implemented in the kernels 2.6.16+.
4355 // It might work on 2.6.10+ with a special kernel/glibc patch.
4356 // For reference, please, see IEEE Std 1003.1-2004:
4357 // http://www.unix.org/single_unix_specification
4358
4359 jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) {
4360 struct timespec tp;
4361 int rc = os::Linux::clock_gettime(clockid, &tp);
4362 assert(rc == 0, "clock_gettime is expected to return 0 code");
4363
4364 return (tp.tv_sec * NANOSECS_PER_SEC) + tp.tv_nsec;
4365 }
4366
4367 /////
4368 // glibc on Linux platform uses non-documented flag
4369 // to indicate, that some special sort of signal
4370 // trampoline is used.
4371 // We will never set this flag, and we should
4372 // ignore this flag in our diagnostic
4373 #ifdef SIGNIFICANT_SIGNAL_MASK
4374 #undef SIGNIFICANT_SIGNAL_MASK
4375 #endif
4376 #define SIGNIFICANT_SIGNAL_MASK (~0x04000000)
4377
4378 static const char* get_signal_handler_name(address handler,
4379 char* buf, int buflen) {
4380 int offset;
4381 bool found = os::dll_address_to_library_name(handler, buf, buflen, &offset);
4382 if (found) {
4383 // skip directory names
4384 const char *p1, *p2;
4385 p1 = buf;
4386 size_t len = strlen(os::file_separator());
4387 while ((p2 = strstr(p1, os::file_separator())) != NULL) p1 = p2 + len;
4388 jio_snprintf(buf, buflen, "%s+0x%x", p1, offset);
4389 } else {
4390 jio_snprintf(buf, buflen, PTR_FORMAT, handler);
4391 }
4392 return buf;
4393 }
4394
4395 static void print_signal_handler(outputStream* st, int sig,
4396 char* buf, size_t buflen) {
4397 struct sigaction sa;
4398
4399 sigaction(sig, NULL, &sa);
4400
4401 // See comment for SIGNIFICANT_SIGNAL_MASK define
4402 sa.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
4403
4404 st->print("%s: ", os::exception_name(sig, buf, buflen));
4405
4406 address handler = (sa.sa_flags & SA_SIGINFO)
4407 ? CAST_FROM_FN_PTR(address, sa.sa_sigaction)
4408 : CAST_FROM_FN_PTR(address, sa.sa_handler);
4409
4410 if (handler == CAST_FROM_FN_PTR(address, SIG_DFL)) {
4411 st->print("SIG_DFL");
4412 } else if (handler == CAST_FROM_FN_PTR(address, SIG_IGN)) {
4413 st->print("SIG_IGN");
4414 } else {
4415 st->print("[%s]", get_signal_handler_name(handler, buf, buflen));
4416 }
4417
4418 st->print(", sa_mask[0]=");
4419 os::Posix::print_signal_set_short(st, &sa.sa_mask);
4420
4421 address rh = VMError::get_resetted_sighandler(sig);
4422 // May be, handler was resetted by VMError?
4423 if(rh != NULL) {
4424 handler = rh;
4425 sa.sa_flags = VMError::get_resetted_sigflags(sig) & SIGNIFICANT_SIGNAL_MASK;
4426 }
4427
4428 st->print(", sa_flags=");
4429 os::Posix::print_sa_flags(st, sa.sa_flags);
4430
4431 // Check: is it our handler?
4432 if(handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler) ||
4433 handler == CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler)) {
4434 // It is our signal handler
4435 // check for flags, reset system-used one!
4436 if((int)sa.sa_flags != os::Linux::get_our_sigflags(sig)) {
4437 st->print(
4438 ", flags was changed from " PTR32_FORMAT ", consider using jsig library",
4439 os::Linux::get_our_sigflags(sig));
4440 }
4441 }
4442 st->cr();
4443 }
4444
4445
4446 #define DO_SIGNAL_CHECK(sig) \
4447 if (!sigismember(&check_signal_done, sig)) \
4448 os::Linux::check_signal_handler(sig)
4449
4450 // This method is a periodic task to check for misbehaving JNI applications
4451 // under CheckJNI, we can add any periodic checks here
4452
4453 void os::run_periodic_checks() {
4454
4455 if (check_signals == false) return;
4456
4457 // SEGV and BUS if overridden could potentially prevent
4458 // generation of hs*.log in the event of a crash, debugging
4459 // such a case can be very challenging, so we absolutely
4460 // check the following for a good measure:
4461 DO_SIGNAL_CHECK(SIGSEGV);
4462 DO_SIGNAL_CHECK(SIGILL);
4463 DO_SIGNAL_CHECK(SIGFPE);
4464 DO_SIGNAL_CHECK(SIGBUS);
4465 DO_SIGNAL_CHECK(SIGPIPE);
4466 DO_SIGNAL_CHECK(SIGXFSZ);
4467 #if defined(PPC64)
4468 DO_SIGNAL_CHECK(SIGTRAP);
4469 #endif
4470
4471 // ReduceSignalUsage allows the user to override these handlers
4472 // see comments at the very top and jvm_solaris.h
4473 if (!ReduceSignalUsage) {
4474 DO_SIGNAL_CHECK(SHUTDOWN1_SIGNAL);
4475 DO_SIGNAL_CHECK(SHUTDOWN2_SIGNAL);
4476 DO_SIGNAL_CHECK(SHUTDOWN3_SIGNAL);
4477 DO_SIGNAL_CHECK(BREAK_SIGNAL);
4478 }
4479
4480 DO_SIGNAL_CHECK(SR_signum);
4481 DO_SIGNAL_CHECK(INTERRUPT_SIGNAL);
4482 }
4483
4484 typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *);
4485
4486 static os_sigaction_t os_sigaction = NULL;
4487
4488 void os::Linux::check_signal_handler(int sig) {
4489 char buf[O_BUFLEN];
4490 address jvmHandler = NULL;
4491
4492
4493 struct sigaction act;
4494 if (os_sigaction == NULL) {
4495 // only trust the default sigaction, in case it has been interposed
4496 os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT, "sigaction");
4497 if (os_sigaction == NULL) return;
4498 }
4499
4500 os_sigaction(sig, (struct sigaction*)NULL, &act);
4501
4502
4503 act.sa_flags &= SIGNIFICANT_SIGNAL_MASK;
4504
4505 address thisHandler = (act.sa_flags & SA_SIGINFO)
4506 ? CAST_FROM_FN_PTR(address, act.sa_sigaction)
4507 : CAST_FROM_FN_PTR(address, act.sa_handler) ;
4508
4509
4510 switch(sig) {
4511 case SIGSEGV:
4512 case SIGBUS:
4513 case SIGFPE:
4514 case SIGPIPE:
4515 case SIGILL:
4516 case SIGXFSZ:
4517 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)signalHandler);
4518 break;
4519
4520 case SHUTDOWN1_SIGNAL:
4521 case SHUTDOWN2_SIGNAL:
4522 case SHUTDOWN3_SIGNAL:
4523 case BREAK_SIGNAL:
4524 jvmHandler = (address)user_handler();
4525 break;
4526
4527 case INTERRUPT_SIGNAL:
4528 jvmHandler = CAST_FROM_FN_PTR(address, SIG_DFL);
4529 break;
4530
4531 default:
4532 if (sig == SR_signum) {
4533 jvmHandler = CAST_FROM_FN_PTR(address, (sa_sigaction_t)SR_handler);
4534 } else {
4535 return;
4536 }
4537 break;
4538 }
4539
4540 if (thisHandler != jvmHandler) {
4541 tty->print("Warning: %s handler ", exception_name(sig, buf, O_BUFLEN));
4542 tty->print("expected:%s", get_signal_handler_name(jvmHandler, buf, O_BUFLEN));
4543 tty->print_cr(" found:%s", get_signal_handler_name(thisHandler, buf, O_BUFLEN));
4544 // No need to check this sig any longer
4545 sigaddset(&check_signal_done, sig);
4546 // Running under non-interactive shell, SHUTDOWN2_SIGNAL will be reassigned SIG_IGN
4547 if (sig == SHUTDOWN2_SIGNAL && !isatty(fileno(stdin))) {
4548 tty->print_cr("Running in non-interactive shell, %s handler is replaced by shell",
4549 exception_name(sig, buf, O_BUFLEN));
4550 }
4551 } else if(os::Linux::get_our_sigflags(sig) != 0 && (int)act.sa_flags != os::Linux::get_our_sigflags(sig)) {
4552 tty->print("Warning: %s handler flags ", exception_name(sig, buf, O_BUFLEN));
4553 tty->print("expected:" PTR32_FORMAT, os::Linux::get_our_sigflags(sig));
4554 tty->print_cr(" found:" PTR32_FORMAT, act.sa_flags);
4555 // No need to check this sig any longer
4556 sigaddset(&check_signal_done, sig);
4557 }
4558
4559 // Dump all the signal
4560 if (sigismember(&check_signal_done, sig)) {
4561 print_signal_handlers(tty, buf, O_BUFLEN);
4562 }
4563 }
4564
4565 extern void report_error(char* file_name, int line_no, char* title, char* format, ...);
4566
4567 extern bool signal_name(int signo, char* buf, size_t len);
4568
4569 const char* os::exception_name(int exception_code, char* buf, size_t size) {
4570 if (0 < exception_code && exception_code <= SIGRTMAX) {
4571 // signal
4572 if (!signal_name(exception_code, buf, size)) {
4573 jio_snprintf(buf, size, "SIG%d", exception_code);
4574 }
4575 return buf;
4576 } else {
4577 return NULL;
4578 }
4579 }
4580
4581 // this is called _before_ the most of global arguments have been parsed
4582 void os::init(void) {
4583 char dummy; /* used to get a guess on initial stack address */
4584 // first_hrtime = gethrtime();
4585
4586 // With LinuxThreads the JavaMain thread pid (primordial thread)
4587 // is different than the pid of the java launcher thread.
4588 // So, on Linux, the launcher thread pid is passed to the VM
4589 // via the sun.java.launcher.pid property.
4590 // Use this property instead of getpid() if it was correctly passed.
4591 // See bug 6351349.
4592 pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid();
4593
4594 _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid();
4595
4596 clock_tics_per_sec = sysconf(_SC_CLK_TCK);
4597
4598 init_random(1234567);
4599
4600 ThreadCritical::initialize();
4601
4602 Linux::set_page_size(sysconf(_SC_PAGESIZE));
4603 if (Linux::page_size() == -1) {
4604 fatal(err_msg("os_linux.cpp: os::init: sysconf failed (%s)",
4605 strerror(errno)));
4606 }
4607 init_page_sizes((size_t) Linux::page_size());
4608
4609 Linux::initialize_system_info();
4610
4611 // main_thread points to the aboriginal thread
4612 Linux::_main_thread = pthread_self();
4613
4614 Linux::clock_init();
4615 initial_time_count = javaTimeNanos();
4616
4617 // pthread_condattr initialization for monotonic clock
4618 int status;
4619 pthread_condattr_t* _condattr = os::Linux::condAttr();
4620 if ((status = pthread_condattr_init(_condattr)) != 0) {
4621 fatal(err_msg("pthread_condattr_init: %s", strerror(status)));
4622 }
4623 // Only set the clock if CLOCK_MONOTONIC is available
4624 if (os::supports_monotonic_clock()) {
4625 if ((status = pthread_condattr_setclock(_condattr, CLOCK_MONOTONIC)) != 0) {
4626 if (status == EINVAL) {
4627 warning("Unable to use monotonic clock with relative timed-waits" \
4628 " - changes to the time-of-day clock may have adverse affects");
4629 } else {
4630 fatal(err_msg("pthread_condattr_setclock: %s", strerror(status)));
4631 }
4632 }
4633 }
4634 // else it defaults to CLOCK_REALTIME
4635
4636 pthread_mutex_init(&dl_mutex, NULL);
4637
4638 // If the pagesize of the VM is greater than 8K determine the appropriate
4639 // number of initial guard pages. The user can change this with the
4640 // command line arguments, if needed.
4641 if (vm_page_size() > (int)Linux::vm_default_page_size()) {
4642 StackYellowPages = 1;
4643 StackRedPages = 1;
4644 StackShadowPages = round_to((StackShadowPages*Linux::vm_default_page_size()), vm_page_size()) / vm_page_size();
4645 }
4646 }
4647
4648 // To install functions for atexit system call
4649 extern "C" {
4650 static void perfMemory_exit_helper() {
4651 perfMemory_exit();
4652 }
4653 }
4654
4655 // this is called _after_ the global arguments have been parsed
4656 jint os::init_2(void)
4657 {
4658 Linux::fast_thread_clock_init();
4659
4660 // Allocate a single page and mark it as readable for safepoint polling
4661 address polling_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
4662 guarantee( polling_page != MAP_FAILED, "os::init_2: failed to allocate polling page" );
4663
4664 os::set_polling_page( polling_page );
4665
4666 #ifndef PRODUCT
4667 if(Verbose && PrintMiscellaneous)
4668 tty->print("[SafePoint Polling address: " INTPTR_FORMAT "]\n", (intptr_t)polling_page);
4669 #endif
4670
4671 if (!UseMembar) {
4672 address mem_serialize_page = (address) ::mmap(NULL, Linux::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
4673 guarantee( mem_serialize_page != MAP_FAILED, "mmap Failed for memory serialize page");
4674 os::set_memory_serialize_page( mem_serialize_page );
4675
4676 #ifndef PRODUCT
4677 if(Verbose && PrintMiscellaneous)
4678 tty->print("[Memory Serialize Page address: " INTPTR_FORMAT "]\n", (intptr_t)mem_serialize_page);
4679 #endif
4680 }
4681
4682 // initialize suspend/resume support - must do this before signal_sets_init()
4683 if (SR_initialize() != 0) {
4684 perror("SR_initialize failed");
4685 return JNI_ERR;
4686 }
4687
4688 Linux::signal_sets_init();
4689 Linux::install_signal_handlers();
4690
4691 // Check minimum allowable stack size for thread creation and to initialize
4692 // the java system classes, including StackOverflowError - depends on page
4693 // size. Add a page for compiler2 recursion in main thread.
4694 // Add in 2*BytesPerWord times page size to account for VM stack during
4695 // class initialization depending on 32 or 64 bit VM.
4696 os::Linux::min_stack_allowed = MAX2(os::Linux::min_stack_allowed,
4697 (size_t)(StackYellowPages+StackRedPages+StackShadowPages) * Linux::page_size() +
4698 (2*BytesPerWord COMPILER2_PRESENT(+1)) * Linux::vm_default_page_size());
4699
4700 size_t threadStackSizeInBytes = ThreadStackSize * K;
4701 if (threadStackSizeInBytes != 0 &&
4702 threadStackSizeInBytes < os::Linux::min_stack_allowed) {
4703 tty->print_cr("\nThe stack size specified is too small, "
4704 "Specify at least %dk",
4705 os::Linux::min_stack_allowed/ K);
4706 return JNI_ERR;
4707 }
4708
4709 // Make the stack size a multiple of the page size so that
4710 // the yellow/red zones can be guarded.
4711 JavaThread::set_stack_size_at_create(round_to(threadStackSizeInBytes,
4712 vm_page_size()));
4713
4714 Linux::capture_initial_stack(JavaThread::stack_size_at_create());
4715
4716 #if defined(IA32)
4717 workaround_expand_exec_shield_cs_limit();
4718 #endif
4719
4720 Linux::libpthread_init();
4721 if (PrintMiscellaneous && (Verbose || WizardMode)) {
4722 tty->print_cr("[HotSpot is running with %s, %s(%s)]\n",
4723 Linux::glibc_version(), Linux::libpthread_version(),
4724 Linux::is_floating_stack() ? "floating stack" : "fixed stack");
4725 }
4726
4727 if (UseNUMA) {
4728 if (!Linux::libnuma_init()) {
4729 UseNUMA = false;
4730 } else {
4731 if ((Linux::numa_max_node() < 1)) {
4732 // There's only one node(they start from 0), disable NUMA.
4733 UseNUMA = false;
4734 }
4735 }
4736 // With SHM and HugeTLBFS large pages we cannot uncommit a page, so there's no way
4737 // we can make the adaptive lgrp chunk resizing work. If the user specified
4738 // both UseNUMA and UseLargePages (or UseSHM/UseHugeTLBFS) on the command line - warn and
4739 // disable adaptive resizing.
4740 if (UseNUMA && UseLargePages && !can_commit_large_page_memory()) {
4741 if (FLAG_IS_DEFAULT(UseNUMA)) {
4742 UseNUMA = false;
4743 } else {
4744 if (FLAG_IS_DEFAULT(UseLargePages) &&
4745 FLAG_IS_DEFAULT(UseSHM) &&
4746 FLAG_IS_DEFAULT(UseHugeTLBFS)) {
4747 UseLargePages = false;
4748 } else {
4749 warning("UseNUMA is not fully compatible with SHM/HugeTLBFS large pages, disabling adaptive resizing");
4750 UseAdaptiveSizePolicy = false;
4751 UseAdaptiveNUMAChunkSizing = false;
4752 }
4753 }
4754 }
4755 if (!UseNUMA && ForceNUMA) {
4756 UseNUMA = true;
4757 }
4758 }
4759
4760 if (MaxFDLimit) {
4761 // set the number of file descriptors to max. print out error
4762 // if getrlimit/setrlimit fails but continue regardless.
4763 struct rlimit nbr_files;
4764 int status = getrlimit(RLIMIT_NOFILE, &nbr_files);
4765 if (status != 0) {
4766 if (PrintMiscellaneous && (Verbose || WizardMode))
4767 perror("os::init_2 getrlimit failed");
4768 } else {
4769 nbr_files.rlim_cur = nbr_files.rlim_max;
4770 status = setrlimit(RLIMIT_NOFILE, &nbr_files);
4771 if (status != 0) {
4772 if (PrintMiscellaneous && (Verbose || WizardMode))
4773 perror("os::init_2 setrlimit failed");
4774 }
4775 }
4776 }
4777
4778 // Initialize lock used to serialize thread creation (see os::create_thread)
4779 Linux::set_createThread_lock(new Mutex(Mutex::leaf, "createThread_lock", false));
4780
4781 // at-exit methods are called in the reverse order of their registration.
4782 // atexit functions are called on return from main or as a result of a
4783 // call to exit(3C). There can be only 32 of these functions registered
4784 // and atexit() does not set errno.
4785
4786 if (PerfAllowAtExitRegistration) {
4787 // only register atexit functions if PerfAllowAtExitRegistration is set.
4788 // atexit functions can be delayed until process exit time, which
4789 // can be problematic for embedded VM situations. Embedded VMs should
4790 // call DestroyJavaVM() to assure that VM resources are released.
4791
4792 // note: perfMemory_exit_helper atexit function may be removed in
4793 // the future if the appropriate cleanup code can be added to the
4794 // VM_Exit VMOperation's doit method.
4795 if (atexit(perfMemory_exit_helper) != 0) {
4796 warning("os::init_2 atexit(perfMemory_exit_helper) failed");
4797 }
4798 }
4799
4800 // initialize thread priority policy
4801 prio_init();
4802
4803 return JNI_OK;
4804 }
4805
4806 // this is called at the end of vm_initialization
4807 void os::init_3(void) {
4808 #ifdef JAVASE_EMBEDDED
4809 // Start the MemNotifyThread
4810 if (LowMemoryProtection) {
4811 MemNotifyThread::start();
4812 }
4813 return;
4814 #endif
4815 }
4816
4817 // Mark the polling page as unreadable
4818 void os::make_polling_page_unreadable(void) {
4819 if( !guard_memory((char*)_polling_page, Linux::page_size()) )
4820 fatal("Could not disable polling page");
4821 };
4822
4823 // Mark the polling page as readable
4824 void os::make_polling_page_readable(void) {
4825 if( !linux_mprotect((char *)_polling_page, Linux::page_size(), PROT_READ)) {
4826 fatal("Could not enable polling page");
4827 }
4828 };
4829
4830 int os::active_processor_count() {
4831 // Linux doesn't yet have a (official) notion of processor sets,
4832 // so just return the number of online processors.
4833 int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN);
4834 assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check");
4835 return online_cpus;
4836 }
4837
4838 void os::set_native_thread_name(const char *name) {
4839 // Not yet implemented.
4840 return;
4841 }
4842
4843 bool os::distribute_processes(uint length, uint* distribution) {
4844 // Not yet implemented.
4845 return false;
4846 }
4847
4848 bool os::bind_to_processor(uint processor_id) {
4849 // Not yet implemented.
4850 return false;
4851 }
4852
4853 ///
4854
4855 void os::SuspendedThreadTask::internal_do_task() {
4856 if (do_suspend(_thread->osthread())) {
4857 SuspendedThreadTaskContext context(_thread, _thread->osthread()->ucontext());
4858 do_task(context);
4859 do_resume(_thread->osthread());
4860 }
4861 }
4862
4863 class PcFetcher : public os::SuspendedThreadTask {
4864 public:
4865 PcFetcher(Thread* thread) : os::SuspendedThreadTask(thread) {}
4866 ExtendedPC result();
4867 protected:
4868 void do_task(const os::SuspendedThreadTaskContext& context);
4869 private:
4870 ExtendedPC _epc;
4871 };
4872
4873 ExtendedPC PcFetcher::result() {
4874 guarantee(is_done(), "task is not done yet.");
4875 return _epc;
4876 }
4877
4878 void PcFetcher::do_task(const os::SuspendedThreadTaskContext& context) {
4879 Thread* thread = context.thread();
4880 OSThread* osthread = thread->osthread();
4881 if (osthread->ucontext() != NULL) {
4882 _epc = os::Linux::ucontext_get_pc((ucontext_t *) context.ucontext());
4883 } else {
4884 // NULL context is unexpected, double-check this is the VMThread
4885 guarantee(thread->is_VM_thread(), "can only be called for VMThread");
4886 }
4887 }
4888
4889 // Suspends the target using the signal mechanism and then grabs the PC before
4890 // resuming the target. Used by the flat-profiler only
4891 ExtendedPC os::get_thread_pc(Thread* thread) {
4892 // Make sure that it is called by the watcher for the VMThread
4893 assert(Thread::current()->is_Watcher_thread(), "Must be watcher");
4894 assert(thread->is_VM_thread(), "Can only be called for VMThread");
4895
4896 PcFetcher fetcher(thread);
4897 fetcher.run();
4898 return fetcher.result();
4899 }
4900
4901 int os::Linux::safe_cond_timedwait(pthread_cond_t *_cond, pthread_mutex_t *_mutex, const struct timespec *_abstime)
4902 {
4903 if (is_NPTL()) {
4904 return pthread_cond_timedwait(_cond, _mutex, _abstime);
4905 } else {
4906 // 6292965: LinuxThreads pthread_cond_timedwait() resets FPU control
4907 // word back to default 64bit precision if condvar is signaled. Java
4908 // wants 53bit precision. Save and restore current value.
4909 int fpu = get_fpu_control_word();
4910 int status = pthread_cond_timedwait(_cond, _mutex, _abstime);
4911 set_fpu_control_word(fpu);
4912 return status;
4913 }
4914 }
4915
4916 ////////////////////////////////////////////////////////////////////////////////
4917 // debug support
4918
4919 bool os::find(address addr, outputStream* st) {
4920 Dl_info dlinfo;
4921 memset(&dlinfo, 0, sizeof(dlinfo));
4922 if (dladdr(addr, &dlinfo) != 0) {
4923 st->print(PTR_FORMAT ": ", addr);
4924 if (dlinfo.dli_sname != NULL && dlinfo.dli_saddr != NULL) {
4925 st->print("%s+%#x", dlinfo.dli_sname,
4926 addr - (intptr_t)dlinfo.dli_saddr);
4927 } else if (dlinfo.dli_fbase != NULL) {
4928 st->print("<offset %#x>", addr - (intptr_t)dlinfo.dli_fbase);
4929 } else {
4930 st->print("<absolute address>");
4931 }
4932 if (dlinfo.dli_fname != NULL) {
4933 st->print(" in %s", dlinfo.dli_fname);
4934 }
4935 if (dlinfo.dli_fbase != NULL) {
4936 st->print(" at " PTR_FORMAT, dlinfo.dli_fbase);
4937 }
4938 st->cr();
4939
4940 if (Verbose) {
4941 // decode some bytes around the PC
4942 address begin = clamp_address_in_page(addr-40, addr, os::vm_page_size());
4943 address end = clamp_address_in_page(addr+40, addr, os::vm_page_size());
4944 address lowest = (address) dlinfo.dli_sname;
4945 if (!lowest) lowest = (address) dlinfo.dli_fbase;
4946 if (begin < lowest) begin = lowest;
4947 Dl_info dlinfo2;
4948 if (dladdr(end, &dlinfo2) != 0 && dlinfo2.dli_saddr != dlinfo.dli_saddr
4949 && end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin)
4950 end = (address) dlinfo2.dli_saddr;
4951 Disassembler::decode(begin, end, st);
4952 }
4953 return true;
4954 }
4955 return false;
4956 }
4957
4958 ////////////////////////////////////////////////////////////////////////////////
4959 // misc
4960
4961 // This does not do anything on Linux. This is basically a hook for being
4962 // able to use structured exception handling (thread-local exception filters)
4963 // on, e.g., Win32.
4964 void
4965 os::os_exception_wrapper(java_call_t f, JavaValue* value, methodHandle* method,
4966 JavaCallArguments* args, Thread* thread) {
4967 f(value, method, args, thread);
4968 }
4969
4970 void os::print_statistics() {
4971 }
4972
4973 int os::message_box(const char* title, const char* message) {
4974 int i;
4975 fdStream err(defaultStream::error_fd());
4976 for (i = 0; i < 78; i++) err.print_raw("=");
4977 err.cr();
4978 err.print_raw_cr(title);
4979 for (i = 0; i < 78; i++) err.print_raw("-");
4980 err.cr();
4981 err.print_raw_cr(message);
4982 for (i = 0; i < 78; i++) err.print_raw("=");
4983 err.cr();
4984
4985 char buf[16];
4986 // Prevent process from exiting upon "read error" without consuming all CPU
4987 while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); }
4988
4989 return buf[0] == 'y' || buf[0] == 'Y';
4990 }
4991
4992 int os::stat(const char *path, struct stat *sbuf) {
4993 char pathbuf[MAX_PATH];
4994 if (strlen(path) > MAX_PATH - 1) {
4995 errno = ENAMETOOLONG;
4996 return -1;
4997 }
4998 os::native_path(strcpy(pathbuf, path));
4999 return ::stat(pathbuf, sbuf);
5000 }
5001
5002 bool os::check_heap(bool force) {
5003 return true;
5004 }
5005
5006 int local_vsnprintf(char* buf, size_t count, const char* format, va_list args) {
5007 return ::vsnprintf(buf, count, format, args);
5008 }
5009
5010 // Is a (classpath) directory empty?
5011 bool os::dir_is_empty(const char* path) {
5012 DIR *dir = NULL;
5013 struct dirent *ptr;
5014
5015 dir = opendir(path);
5016 if (dir == NULL) return true;
5017
5018 /* Scan the directory */
5019 bool result = true;
5020 char buf[sizeof(struct dirent) + MAX_PATH];
5021 while (result && (ptr = ::readdir(dir)) != NULL) {
5022 if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) {
5023 result = false;
5024 }
5025 }
5026 closedir(dir);
5027 return result;
5028 }
5029
5030 // This code originates from JDK's sysOpen and open64_w
5031 // from src/solaris/hpi/src/system_md.c
5032
5033 #ifndef O_DELETE
5034 #define O_DELETE 0x10000
5035 #endif
5036
5037 // Open a file. Unlink the file immediately after open returns
5038 // if the specified oflag has the O_DELETE flag set.
5039 // O_DELETE is used only in j2se/src/share/native/java/util/zip/ZipFile.c
5040
5041 int os::open(const char *path, int oflag, int mode) {
5042
5043 if (strlen(path) > MAX_PATH - 1) {
5044 errno = ENAMETOOLONG;
5045 return -1;
5046 }
5047 int fd;
5048 int o_delete = (oflag & O_DELETE);
5049 oflag = oflag & ~O_DELETE;
5050
5051 fd = ::open64(path, oflag, mode);
5052 if (fd == -1) return -1;
5053
5054 //If the open succeeded, the file might still be a directory
5055 {
5056 struct stat64 buf64;
5057 int ret = ::fstat64(fd, &buf64);
5058 int st_mode = buf64.st_mode;
5059
5060 if (ret != -1) {
5061 if ((st_mode & S_IFMT) == S_IFDIR) {
5062 errno = EISDIR;
5063 ::close(fd);
5064 return -1;
5065 }
5066 } else {
5067 ::close(fd);
5068 return -1;
5069 }
5070 }
5071
5072 /*
5073 * All file descriptors that are opened in the JVM and not
5074 * specifically destined for a subprocess should have the
5075 * close-on-exec flag set. If we don't set it, then careless 3rd
5076 * party native code might fork and exec without closing all
5077 * appropriate file descriptors (e.g. as we do in closeDescriptors in
5078 * UNIXProcess.c), and this in turn might:
5079 *
5080 * - cause end-of-file to fail to be detected on some file
5081 * descriptors, resulting in mysterious hangs, or
5082 *
5083 * - might cause an fopen in the subprocess to fail on a system
5084 * suffering from bug 1085341.
5085 *
5086 * (Yes, the default setting of the close-on-exec flag is a Unix
5087 * design flaw)
5088 *
5089 * See:
5090 * 1085341: 32-bit stdio routines should support file descriptors >255
5091 * 4843136: (process) pipe file descriptor from Runtime.exec not being closed
5092 * 6339493: (process) Runtime.exec does not close all file descriptors on Solaris 9
5093 */
5094 #ifdef FD_CLOEXEC
5095 {
5096 int flags = ::fcntl(fd, F_GETFD);
5097 if (flags != -1)
5098 ::fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
5099 }
5100 #endif
5101
5102 if (o_delete != 0) {
5103 ::unlink(path);
5104 }
5105 return fd;
5106 }
5107
5108
5109 // create binary file, rewriting existing file if required
5110 int os::create_binary_file(const char* path, bool rewrite_existing) {
5111 int oflags = O_WRONLY | O_CREAT;
5112 if (!rewrite_existing) {
5113 oflags |= O_EXCL;
5114 }
5115 return ::open64(path, oflags, S_IREAD | S_IWRITE);
5116 }
5117
5118 // return current position of file pointer
5119 jlong os::current_file_offset(int fd) {
5120 return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR);
5121 }
5122
5123 // move file pointer to the specified offset
5124 jlong os::seek_to_file_offset(int fd, jlong offset) {
5125 return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET);
5126 }
5127
5128 // This code originates from JDK's sysAvailable
5129 // from src/solaris/hpi/src/native_threads/src/sys_api_td.c
5130
5131 int os::available(int fd, jlong *bytes) {
5132 jlong cur, end;
5133 int mode;
5134 struct stat64 buf64;
5135
5136 if (::fstat64(fd, &buf64) >= 0) {
5137 mode = buf64.st_mode;
5138 if (S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) {
5139 /*
5140 * XXX: is the following call interruptible? If so, this might
5141 * need to go through the INTERRUPT_IO() wrapper as for other
5142 * blocking, interruptible calls in this file.
5143 */
5144 int n;
5145 if (::ioctl(fd, FIONREAD, &n) >= 0) {
5146 *bytes = n;
5147 return 1;
5148 }
5149 }
5150 }
5151 if ((cur = ::lseek64(fd, 0L, SEEK_CUR)) == -1) {
5152 return 0;
5153 } else if ((end = ::lseek64(fd, 0L, SEEK_END)) == -1) {
5154 return 0;
5155 } else if (::lseek64(fd, cur, SEEK_SET) == -1) {
5156 return 0;
5157 }
5158 *bytes = end - cur;
5159 return 1;
5160 }
5161
5162 int os::socket_available(int fd, jint *pbytes) {
5163 // Linux doc says EINTR not returned, unlike Solaris
5164 int ret = ::ioctl(fd, FIONREAD, pbytes);
5165
5166 //%% note ioctl can return 0 when successful, JVM_SocketAvailable
5167 // is expected to return 0 on failure and 1 on success to the jdk.
5168 return (ret < 0) ? 0 : 1;
5169 }
5170
5171 // Map a block of memory.
5172 char* os::pd_map_memory(int fd, const char* file_name, size_t file_offset,
5173 char *addr, size_t bytes, bool read_only,
5174 bool allow_exec) {
5175 int prot;
5176 int flags = MAP_PRIVATE;
5177
5178 if (read_only) {
5179 prot = PROT_READ;
5180 } else {
5181 prot = PROT_READ | PROT_WRITE;
5182 }
5183
5184 if (allow_exec) {
5185 prot |= PROT_EXEC;
5186 }
5187
5188 if (addr != NULL) {
5189 flags |= MAP_FIXED;
5190 }
5191
5192 char* mapped_address = (char*)mmap(addr, (size_t)bytes, prot, flags,
5193 fd, file_offset);
5194 if (mapped_address == MAP_FAILED) {
5195 return NULL;
5196 }
5197 return mapped_address;
5198 }
5199
5200
5201 // Remap a block of memory.
5202 char* os::pd_remap_memory(int fd, const char* file_name, size_t file_offset,
5203 char *addr, size_t bytes, bool read_only,
5204 bool allow_exec) {
5205 // same as map_memory() on this OS
5206 return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only,
5207 allow_exec);
5208 }
5209
5210
5211 // Unmap a block of memory.
5212 bool os::pd_unmap_memory(char* addr, size_t bytes) {
5213 return munmap(addr, bytes) == 0;
5214 }
5215
5216 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time);
5217
5218 static clockid_t thread_cpu_clockid(Thread* thread) {
5219 pthread_t tid = thread->osthread()->pthread_id();
5220 clockid_t clockid;
5221
5222 // Get thread clockid
5223 int rc = os::Linux::pthread_getcpuclockid(tid, &clockid);
5224 assert(rc == 0, "pthread_getcpuclockid is expected to return 0 code");
5225 return clockid;
5226 }
5227
5228 // current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool)
5229 // are used by JVM M&M and JVMTI to get user+sys or user CPU time
5230 // of a thread.
5231 //
5232 // current_thread_cpu_time() and thread_cpu_time(Thread*) returns
5233 // the fast estimate available on the platform.
5234
5235 jlong os::current_thread_cpu_time() {
5236 if (os::Linux::supports_fast_thread_cpu_time()) {
5237 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
5238 } else {
5239 // return user + sys since the cost is the same
5240 return slow_thread_cpu_time(Thread::current(), true /* user + sys */);
5241 }
5242 }
5243
5244 jlong os::thread_cpu_time(Thread* thread) {
5245 // consistent with what current_thread_cpu_time() returns
5246 if (os::Linux::supports_fast_thread_cpu_time()) {
5247 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread));
5248 } else {
5249 return slow_thread_cpu_time(thread, true /* user + sys */);
5250 }
5251 }
5252
5253 jlong os::current_thread_cpu_time(bool user_sys_cpu_time) {
5254 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
5255 return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
5256 } else {
5257 return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time);
5258 }
5259 }
5260
5261 jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
5262 if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
5263 return os::Linux::fast_thread_cpu_time(thread_cpu_clockid(thread));
5264 } else {
5265 return slow_thread_cpu_time(thread, user_sys_cpu_time);
5266 }
5267 }
5268
5269 //
5270 // -1 on error.
5271 //
5272
5273 static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
5274 static bool proc_task_unchecked = true;
5275 pid_t tid = thread->osthread()->thread_id();
5276 char *s;
5277 char stat[2048];
5278 int statlen;
5279 char proc_name[64];
5280 int count;
5281 long sys_time, user_time;
5282 char cdummy;
5283 int idummy;
5284 long ldummy;
5285 FILE *fp;
5286
5287 snprintf(proc_name, 64, "/proc/%d/stat", tid);
5288
5289 // The /proc/<tid>/stat aggregates per-process usage on
5290 // new Linux kernels 2.6+ where NPTL is supported.
5291 // The /proc/self/task/<tid>/stat still has the per-thread usage.
5292 // See bug 6328462.
5293 // There possibly can be cases where there is no directory
5294 // /proc/self/task, so we check its availability.
5295 if (proc_task_unchecked && os::Linux::is_NPTL()) {
5296 // This is executed only once
5297 proc_task_unchecked = false;
5298 fp = fopen("/proc/self/task", "r");
5299 if (fp != NULL) {
5300 snprintf(proc_name, 64, "/proc/self/task/%d/stat", tid);
5301 fclose(fp);
5302 }
5303 }
5304
5305 fp = fopen(proc_name, "r");
5306 if ( fp == NULL ) return -1;
5307 statlen = fread(stat, 1, 2047, fp);
5308 stat[statlen] = '\0';
5309 fclose(fp);
5310
5311 // Skip pid and the command string. Note that we could be dealing with
5312 // weird command names, e.g. user could decide to rename java launcher
5313 // to "java 1.4.2 :)", then the stat file would look like
5314 // 1234 (java 1.4.2 :)) R ... ...
5315 // We don't really need to know the command string, just find the last
5316 // occurrence of ")" and then start parsing from there. See bug 4726580.
5317 s = strrchr(stat, ')');
5318 if (s == NULL ) return -1;
5319
5320 // Skip blank chars
5321 do s++; while (isspace(*s));
5322
5323 count = sscanf(s,"%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu",
5324 &cdummy, &idummy, &idummy, &idummy, &idummy, &idummy,
5325 &ldummy, &ldummy, &ldummy, &ldummy, &ldummy,
5326 &user_time, &sys_time);
5327 if ( count != 13 ) return -1;
5328 if (user_sys_cpu_time) {
5329 return ((jlong)sys_time + (jlong)user_time) * (1000000000 / clock_tics_per_sec);
5330 } else {
5331 return (jlong)user_time * (1000000000 / clock_tics_per_sec);
5332 }
5333 }
5334
5335 void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
5336 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits
5337 info_ptr->may_skip_backward = false; // elapsed time not wall time
5338 info_ptr->may_skip_forward = false; // elapsed time not wall time
5339 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned
5340 }
5341
5342 void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
5343 info_ptr->max_value = ALL_64_BITS; // will not wrap in less than 64 bits
5344 info_ptr->may_skip_backward = false; // elapsed time not wall time
5345 info_ptr->may_skip_forward = false; // elapsed time not wall time
5346 info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned
5347 }
5348
5349 bool os::is_thread_cpu_time_supported() {
5350 return true;
5351 }
5352
5353 // System loadavg support. Returns -1 if load average cannot be obtained.
5354 // Linux doesn't yet have a (official) notion of processor sets,
5355 // so just return the system wide load average.
5356 int os::loadavg(double loadavg[], int nelem) {
5357 return ::getloadavg(loadavg, nelem);
5358 }
5359
5360 void os::pause() {
5361 char filename[MAX_PATH];
5362 if (PauseAtStartupFile && PauseAtStartupFile[0]) {
5363 jio_snprintf(filename, MAX_PATH, PauseAtStartupFile);
5364 } else {
5365 jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id());
5366 }
5367
5368 int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
5369 if (fd != -1) {
5370 struct stat buf;
5371 ::close(fd);
5372 while (::stat(filename, &buf) == 0) {
5373 (void)::poll(NULL, 0, 100);
5374 }
5375 } else {
5376 jio_fprintf(stderr,
5377 "Could not open pause file '%s', continuing immediately.\n", filename);
5378 }
5379 }
5380
5381
5382 // Refer to the comments in os_solaris.cpp park-unpark.
5383 //
5384 // Beware -- Some versions of NPTL embody a flaw where pthread_cond_timedwait() can
5385 // hang indefinitely. For instance NPTL 0.60 on 2.4.21-4ELsmp is vulnerable.
5386 // For specifics regarding the bug see GLIBC BUGID 261237 :
5387 // http://www.mail-archive.com/debian-glibc@lists.debian.org/msg10837.html.
5388 // Briefly, pthread_cond_timedwait() calls with an expiry time that's not in the future
5389 // will either hang or corrupt the condvar, resulting in subsequent hangs if the condvar
5390 // is used. (The simple C test-case provided in the GLIBC bug report manifests the
5391 // hang). The JVM is vulernable via sleep(), Object.wait(timo), LockSupport.parkNanos()
5392 // and monitorenter when we're using 1-0 locking. All those operations may result in
5393 // calls to pthread_cond_timedwait(). Using LD_ASSUME_KERNEL to use an older version
5394 // of libpthread avoids the problem, but isn't practical.
5395 //
5396 // Possible remedies:
5397 //
5398 // 1. Establish a minimum relative wait time. 50 to 100 msecs seems to work.
5399 // This is palliative and probabilistic, however. If the thread is preempted
5400 // between the call to compute_abstime() and pthread_cond_timedwait(), more
5401 // than the minimum period may have passed, and the abstime may be stale (in the
5402 // past) resultin in a hang. Using this technique reduces the odds of a hang
5403 // but the JVM is still vulnerable, particularly on heavily loaded systems.
5404 //
5405 // 2. Modify park-unpark to use per-thread (per ParkEvent) pipe-pairs instead
5406 // of the usual flag-condvar-mutex idiom. The write side of the pipe is set
5407 // NDELAY. unpark() reduces to write(), park() reduces to read() and park(timo)
5408 // reduces to poll()+read(). This works well, but consumes 2 FDs per extant
5409 // thread.
5410 //
5411 // 3. Embargo pthread_cond_timedwait() and implement a native "chron" thread
5412 // that manages timeouts. We'd emulate pthread_cond_timedwait() by enqueuing
5413 // a timeout request to the chron thread and then blocking via pthread_cond_wait().
5414 // This also works well. In fact it avoids kernel-level scalability impediments
5415 // on certain platforms that don't handle lots of active pthread_cond_timedwait()
5416 // timers in a graceful fashion.
5417 //
5418 // 4. When the abstime value is in the past it appears that control returns
5419 // correctly from pthread_cond_timedwait(), but the condvar is left corrupt.
5420 // Subsequent timedwait/wait calls may hang indefinitely. Given that, we
5421 // can avoid the problem by reinitializing the condvar -- by cond_destroy()
5422 // followed by cond_init() -- after all calls to pthread_cond_timedwait().
5423 // It may be possible to avoid reinitialization by checking the return
5424 // value from pthread_cond_timedwait(). In addition to reinitializing the
5425 // condvar we must establish the invariant that cond_signal() is only called
5426 // within critical sections protected by the adjunct mutex. This prevents
5427 // cond_signal() from "seeing" a condvar that's in the midst of being
5428 // reinitialized or that is corrupt. Sadly, this invariant obviates the
5429 // desirable signal-after-unlock optimization that avoids futile context switching.
5430 //
5431 // I'm also concerned that some versions of NTPL might allocate an auxilliary
5432 // structure when a condvar is used or initialized. cond_destroy() would
5433 // release the helper structure. Our reinitialize-after-timedwait fix
5434 // put excessive stress on malloc/free and locks protecting the c-heap.
5435 //
5436 // We currently use (4). See the WorkAroundNTPLTimedWaitHang flag.
5437 // It may be possible to refine (4) by checking the kernel and NTPL verisons
5438 // and only enabling the work-around for vulnerable environments.
5439
5440 // utility to compute the abstime argument to timedwait:
5441 // millis is the relative timeout time
5442 // abstime will be the absolute timeout time
5443 // TODO: replace compute_abstime() with unpackTime()
5444
5445 static struct timespec* compute_abstime(timespec* abstime, jlong millis) {
5446 if (millis < 0) millis = 0;
5447
5448 jlong seconds = millis / 1000;
5449 millis %= 1000;
5450 if (seconds > 50000000) { // see man cond_timedwait(3T)
5451 seconds = 50000000;
5452 }
5453
5454 if (os::supports_monotonic_clock()) {
5455 struct timespec now;
5456 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now);
5457 assert_status(status == 0, status, "clock_gettime");
5458 abstime->tv_sec = now.tv_sec + seconds;
5459 long nanos = now.tv_nsec + millis * NANOSECS_PER_MILLISEC;
5460 if (nanos >= NANOSECS_PER_SEC) {
5461 abstime->tv_sec += 1;
5462 nanos -= NANOSECS_PER_SEC;
5463 }
5464 abstime->tv_nsec = nanos;
5465 } else {
5466 struct timeval now;
5467 int status = gettimeofday(&now, NULL);
5468 assert(status == 0, "gettimeofday");
5469 abstime->tv_sec = now.tv_sec + seconds;
5470 long usec = now.tv_usec + millis * 1000;
5471 if (usec >= 1000000) {
5472 abstime->tv_sec += 1;
5473 usec -= 1000000;
5474 }
5475 abstime->tv_nsec = usec * 1000;
5476 }
5477 return abstime;
5478 }
5479
5480
5481 // Test-and-clear _Event, always leaves _Event set to 0, returns immediately.
5482 // Conceptually TryPark() should be equivalent to park(0).
5483
5484 int os::PlatformEvent::TryPark() {
5485 for (;;) {
5486 const int v = _Event ;
5487 guarantee ((v == 0) || (v == 1), "invariant") ;
5488 if (Atomic::cmpxchg (0, &_Event, v) == v) return v ;
5489 }
5490 }
5491
5492 void os::PlatformEvent::park() { // AKA "down()"
5493 // Invariant: Only the thread associated with the Event/PlatformEvent
5494 // may call park().
5495 // TODO: assert that _Assoc != NULL or _Assoc == Self
5496 int v ;
5497 for (;;) {
5498 v = _Event ;
5499 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ;
5500 }
5501 guarantee (v >= 0, "invariant") ;
5502 if (v == 0) {
5503 // Do this the hard way by blocking ...
5504 int status = pthread_mutex_lock(_mutex);
5505 assert_status(status == 0, status, "mutex_lock");
5506 guarantee (_nParked == 0, "invariant") ;
5507 ++ _nParked ;
5508 while (_Event < 0) {
5509 status = pthread_cond_wait(_cond, _mutex);
5510 // for some reason, under 2.7 lwp_cond_wait() may return ETIME ...
5511 // Treat this the same as if the wait was interrupted
5512 if (status == ETIME) { status = EINTR; }
5513 assert_status(status == 0 || status == EINTR, status, "cond_wait");
5514 }
5515 -- _nParked ;
5516
5517 _Event = 0 ;
5518 status = pthread_mutex_unlock(_mutex);
5519 assert_status(status == 0, status, "mutex_unlock");
5520 // Paranoia to ensure our locked and lock-free paths interact
5521 // correctly with each other.
5522 OrderAccess::fence();
5523 }
5524 guarantee (_Event >= 0, "invariant") ;
5525 }
5526
5527 int os::PlatformEvent::park(jlong millis) {
5528 guarantee (_nParked == 0, "invariant") ;
5529
5530 int v ;
5531 for (;;) {
5532 v = _Event ;
5533 if (Atomic::cmpxchg (v-1, &_Event, v) == v) break ;
5534 }
5535 guarantee (v >= 0, "invariant") ;
5536 if (v != 0) return OS_OK ;
5537
5538 // We do this the hard way, by blocking the thread.
5539 // Consider enforcing a minimum timeout value.
5540 struct timespec abst;
5541 compute_abstime(&abst, millis);
5542
5543 int ret = OS_TIMEOUT;
5544 int status = pthread_mutex_lock(_mutex);
5545 assert_status(status == 0, status, "mutex_lock");
5546 guarantee (_nParked == 0, "invariant") ;
5547 ++_nParked ;
5548
5549 // Object.wait(timo) will return because of
5550 // (a) notification
5551 // (b) timeout
5552 // (c) thread.interrupt
5553 //
5554 // Thread.interrupt and object.notify{All} both call Event::set.
5555 // That is, we treat thread.interrupt as a special case of notification.
5556 // The underlying Solaris implementation, cond_timedwait, admits
5557 // spurious/premature wakeups, but the JLS/JVM spec prevents the
5558 // JVM from making those visible to Java code. As such, we must
5559 // filter out spurious wakeups. We assume all ETIME returns are valid.
5560 //
5561 // TODO: properly differentiate simultaneous notify+interrupt.
5562 // In that case, we should propagate the notify to another waiter.
5563
5564 while (_Event < 0) {
5565 status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst);
5566 if (status != 0 && WorkAroundNPTLTimedWaitHang) {
5567 pthread_cond_destroy (_cond);
5568 pthread_cond_init (_cond, os::Linux::condAttr()) ;
5569 }
5570 assert_status(status == 0 || status == EINTR ||
5571 status == ETIME || status == ETIMEDOUT,
5572 status, "cond_timedwait");
5573 if (!FilterSpuriousWakeups) break ; // previous semantics
5574 if (status == ETIME || status == ETIMEDOUT) break ;
5575 // We consume and ignore EINTR and spurious wakeups.
5576 }
5577 --_nParked ;
5578 if (_Event >= 0) {
5579 ret = OS_OK;
5580 }
5581 _Event = 0 ;
5582 status = pthread_mutex_unlock(_mutex);
5583 assert_status(status == 0, status, "mutex_unlock");
5584 assert (_nParked == 0, "invariant") ;
5585 // Paranoia to ensure our locked and lock-free paths interact
5586 // correctly with each other.
5587 OrderAccess::fence();
5588 return ret;
5589 }
5590
5591 void os::PlatformEvent::unpark() {
5592 // Transitions for _Event:
5593 // 0 :=> 1
5594 // 1 :=> 1
5595 // -1 :=> either 0 or 1; must signal target thread
5596 // That is, we can safely transition _Event from -1 to either
5597 // 0 or 1. Forcing 1 is slightly more efficient for back-to-back
5598 // unpark() calls.
5599 // See also: "Semaphores in Plan 9" by Mullender & Cox
5600 //
5601 // Note: Forcing a transition from "-1" to "1" on an unpark() means
5602 // that it will take two back-to-back park() calls for the owning
5603 // thread to block. This has the benefit of forcing a spurious return
5604 // from the first park() call after an unpark() call which will help
5605 // shake out uses of park() and unpark() without condition variables.
5606
5607 if (Atomic::xchg(1, &_Event) >= 0) return;
5608
5609 // Wait for the thread associated with the event to vacate
5610 int status = pthread_mutex_lock(_mutex);
5611 assert_status(status == 0, status, "mutex_lock");
5612 int AnyWaiters = _nParked;
5613 assert(AnyWaiters == 0 || AnyWaiters == 1, "invariant");
5614 if (AnyWaiters != 0 && WorkAroundNPTLTimedWaitHang) {
5615 AnyWaiters = 0;
5616 pthread_cond_signal(_cond);
5617 }
5618 status = pthread_mutex_unlock(_mutex);
5619 assert_status(status == 0, status, "mutex_unlock");
5620 if (AnyWaiters != 0) {
5621 status = pthread_cond_signal(_cond);
5622 assert_status(status == 0, status, "cond_signal");
5623 }
5624
5625 // Note that we signal() _after dropping the lock for "immortal" Events.
5626 // This is safe and avoids a common class of futile wakeups. In rare
5627 // circumstances this can cause a thread to return prematurely from
5628 // cond_{timed}wait() but the spurious wakeup is benign and the victim will
5629 // simply re-test the condition and re-park itself.
5630 }
5631
5632
5633 // JSR166
5634 // -------------------------------------------------------
5635
5636 /*
5637 * The solaris and linux implementations of park/unpark are fairly
5638 * conservative for now, but can be improved. They currently use a
5639 * mutex/condvar pair, plus a a count.
5640 * Park decrements count if > 0, else does a condvar wait. Unpark
5641 * sets count to 1 and signals condvar. Only one thread ever waits
5642 * on the condvar. Contention seen when trying to park implies that someone
5643 * is unparking you, so don't wait. And spurious returns are fine, so there
5644 * is no need to track notifications.
5645 */
5646
5647 /*
5648 * This code is common to linux and solaris and will be moved to a
5649 * common place in dolphin.
5650 *
5651 * The passed in time value is either a relative time in nanoseconds
5652 * or an absolute time in milliseconds. Either way it has to be unpacked
5653 * into suitable seconds and nanoseconds components and stored in the
5654 * given timespec structure.
5655 * Given time is a 64-bit value and the time_t used in the timespec is only
5656 * a signed-32-bit value (except on 64-bit Linux) we have to watch for
5657 * overflow if times way in the future are given. Further on Solaris versions
5658 * prior to 10 there is a restriction (see cond_timedwait) that the specified
5659 * number of seconds, in abstime, is less than current_time + 100,000,000.
5660 * As it will be 28 years before "now + 100000000" will overflow we can
5661 * ignore overflow and just impose a hard-limit on seconds using the value
5662 * of "now + 100,000,000". This places a limit on the timeout of about 3.17
5663 * years from "now".
5664 */
5665
5666 static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) {
5667 assert (time > 0, "convertTime");
5668 time_t max_secs = 0;
5669
5670 if (!os::supports_monotonic_clock() || isAbsolute) {
5671 struct timeval now;
5672 int status = gettimeofday(&now, NULL);
5673 assert(status == 0, "gettimeofday");
5674
5675 max_secs = now.tv_sec + MAX_SECS;
5676
5677 if (isAbsolute) {
5678 jlong secs = time / 1000;
5679 if (secs > max_secs) {
5680 absTime->tv_sec = max_secs;
5681 } else {
5682 absTime->tv_sec = secs;
5683 }
5684 absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC;
5685 } else {
5686 jlong secs = time / NANOSECS_PER_SEC;
5687 if (secs >= MAX_SECS) {
5688 absTime->tv_sec = max_secs;
5689 absTime->tv_nsec = 0;
5690 } else {
5691 absTime->tv_sec = now.tv_sec + secs;
5692 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000;
5693 if (absTime->tv_nsec >= NANOSECS_PER_SEC) {
5694 absTime->tv_nsec -= NANOSECS_PER_SEC;
5695 ++absTime->tv_sec; // note: this must be <= max_secs
5696 }
5697 }
5698 }
5699 } else {
5700 // must be relative using monotonic clock
5701 struct timespec now;
5702 int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now);
5703 assert_status(status == 0, status, "clock_gettime");
5704 max_secs = now.tv_sec + MAX_SECS;
5705 jlong secs = time / NANOSECS_PER_SEC;
5706 if (secs >= MAX_SECS) {
5707 absTime->tv_sec = max_secs;
5708 absTime->tv_nsec = 0;
5709 } else {
5710 absTime->tv_sec = now.tv_sec + secs;
5711 absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_nsec;
5712 if (absTime->tv_nsec >= NANOSECS_PER_SEC) {
5713 absTime->tv_nsec -= NANOSECS_PER_SEC;
5714 ++absTime->tv_sec; // note: this must be <= max_secs
5715 }
5716 }
5717 }
5718 assert(absTime->tv_sec >= 0, "tv_sec < 0");
5719 assert(absTime->tv_sec <= max_secs, "tv_sec > max_secs");
5720 assert(absTime->tv_nsec >= 0, "tv_nsec < 0");
5721 assert(absTime->tv_nsec < NANOSECS_PER_SEC, "tv_nsec >= nanos_per_sec");
5722 }
5723
5724 void Parker::park(bool isAbsolute, jlong time) {
5725 // Ideally we'd do something useful while spinning, such
5726 // as calling unpackTime().
5727
5728 // Optional fast-path check:
5729 // Return immediately if a permit is available.
5730 // We depend on Atomic::xchg() having full barrier semantics
5731 // since we are doing a lock-free update to _counter.
5732 if (Atomic::xchg(0, &_counter) > 0) return;
5733
5734 Thread* thread = Thread::current();
5735 assert(thread->is_Java_thread(), "Must be JavaThread");
5736 JavaThread *jt = (JavaThread *)thread;
5737
5738 // Optional optimization -- avoid state transitions if there's an interrupt pending.
5739 // Check interrupt before trying to wait
5740 if (Thread::is_interrupted(thread, false)) {
5741 return;
5742 }
5743
5744 // Next, demultiplex/decode time arguments
5745 timespec absTime;
5746 if (time < 0 || (isAbsolute && time == 0) ) { // don't wait at all
5747 return;
5748 }
5749 if (time > 0) {
5750 unpackTime(&absTime, isAbsolute, time);
5751 }
5752
5753
5754 // Enter safepoint region
5755 // Beware of deadlocks such as 6317397.
5756 // The per-thread Parker:: mutex is a classic leaf-lock.
5757 // In particular a thread must never block on the Threads_lock while
5758 // holding the Parker:: mutex. If safepoints are pending both the
5759 // the ThreadBlockInVM() CTOR and DTOR may grab Threads_lock.
5760 ThreadBlockInVM tbivm(jt);
5761
5762 // Don't wait if cannot get lock since interference arises from
5763 // unblocking. Also. check interrupt before trying wait
5764 if (Thread::is_interrupted(thread, false) || pthread_mutex_trylock(_mutex) != 0) {
5765 return;
5766 }
5767
5768 int status ;
5769 if (_counter > 0) { // no wait needed
5770 _counter = 0;
5771 status = pthread_mutex_unlock(_mutex);
5772 assert (status == 0, "invariant") ;
5773 // Paranoia to ensure our locked and lock-free paths interact
5774 // correctly with each other and Java-level accesses.
5775 OrderAccess::fence();
5776 return;
5777 }
5778
5779 #ifdef ASSERT
5780 // Don't catch signals while blocked; let the running threads have the signals.
5781 // (This allows a debugger to break into the running thread.)
5782 sigset_t oldsigs;
5783 sigset_t* allowdebug_blocked = os::Linux::allowdebug_blocked_signals();
5784 pthread_sigmask(SIG_BLOCK, allowdebug_blocked, &oldsigs);
5785 #endif
5786
5787 OSThreadWaitState osts(thread->osthread(), false /* not Object.wait() */);
5788 jt->set_suspend_equivalent();
5789 // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
5790
5791 assert(_cur_index == -1, "invariant");
5792 if (time == 0) {
5793 _cur_index = REL_INDEX; // arbitrary choice when not timed
5794 status = pthread_cond_wait (&_cond[_cur_index], _mutex) ;
5795 } else {
5796 _cur_index = isAbsolute ? ABS_INDEX : REL_INDEX;
5797 status = os::Linux::safe_cond_timedwait (&_cond[_cur_index], _mutex, &absTime) ;
5798 if (status != 0 && WorkAroundNPTLTimedWaitHang) {
5799 pthread_cond_destroy (&_cond[_cur_index]) ;
5800 pthread_cond_init (&_cond[_cur_index], isAbsolute ? NULL : os::Linux::condAttr());
5801 }
5802 }
5803 _cur_index = -1;
5804 assert_status(status == 0 || status == EINTR ||
5805 status == ETIME || status == ETIMEDOUT,
5806 status, "cond_timedwait");
5807
5808 #ifdef ASSERT
5809 pthread_sigmask(SIG_SETMASK, &oldsigs, NULL);
5810 #endif
5811
5812 _counter = 0 ;
5813 status = pthread_mutex_unlock(_mutex) ;
5814 assert_status(status == 0, status, "invariant") ;
5815 // Paranoia to ensure our locked and lock-free paths interact
5816 // correctly with each other and Java-level accesses.
5817 OrderAccess::fence();
5818
5819 // If externally suspended while waiting, re-suspend
5820 if (jt->handle_special_suspend_equivalent_condition()) {
5821 jt->java_suspend_self();
5822 }
5823 }
5824
5825 void Parker::unpark() {
5826 int s, status ;
5827 status = pthread_mutex_lock(_mutex);
5828 assert (status == 0, "invariant") ;
5829 s = _counter;
5830 _counter = 1;
5831 if (s < 1) {
5832 // thread might be parked
5833 if (_cur_index != -1) {
5834 // thread is definitely parked
5835 if (WorkAroundNPTLTimedWaitHang) {
5836 status = pthread_cond_signal (&_cond[_cur_index]);
5837 assert (status == 0, "invariant");
5838 status = pthread_mutex_unlock(_mutex);
5839 assert (status == 0, "invariant");
5840 } else {
5841 status = pthread_mutex_unlock(_mutex);
5842 assert (status == 0, "invariant");
5843 status = pthread_cond_signal (&_cond[_cur_index]);
5844 assert (status == 0, "invariant");
5845 }
5846 } else {
5847 pthread_mutex_unlock(_mutex);
5848 assert (status == 0, "invariant") ;
5849 }
5850 } else {
5851 pthread_mutex_unlock(_mutex);
5852 assert (status == 0, "invariant") ;
5853 }
5854 }
5855
5856
5857 extern char** environ;
5858
5859 #ifndef __NR_fork
5860 #define __NR_fork IA32_ONLY(2) IA64_ONLY(not defined) AMD64_ONLY(57)
5861 #endif
5862
5863 #ifndef __NR_execve
5864 #define __NR_execve IA32_ONLY(11) IA64_ONLY(1033) AMD64_ONLY(59)
5865 #endif
5866
5867 // Run the specified command in a separate process. Return its exit value,
5868 // or -1 on failure (e.g. can't fork a new process).
5869 // Unlike system(), this function can be called from signal handler. It
5870 // doesn't block SIGINT et al.
5871 int os::fork_and_exec(char* cmd) {
5872 const char * argv[4] = {"sh", "-c", cmd, NULL};
5873
5874 // fork() in LinuxThreads/NPTL is not async-safe. It needs to run
5875 // pthread_atfork handlers and reset pthread library. All we need is a
5876 // separate process to execve. Make a direct syscall to fork process.
5877 // On IA64 there's no fork syscall, we have to use fork() and hope for
5878 // the best...
5879 pid_t pid = NOT_IA64(syscall(__NR_fork);)
5880 IA64_ONLY(fork();)
5881
5882 if (pid < 0) {
5883 // fork failed
5884 return -1;
5885
5886 } else if (pid == 0) {
5887 // child process
5888
5889 // execve() in LinuxThreads will call pthread_kill_other_threads_np()
5890 // first to kill every thread on the thread list. Because this list is
5891 // not reset by fork() (see notes above), execve() will instead kill
5892 // every thread in the parent process. We know this is the only thread
5893 // in the new process, so make a system call directly.
5894 // IA64 should use normal execve() from glibc to match the glibc fork()
5895 // above.
5896 NOT_IA64(syscall(__NR_execve, "/bin/sh", argv, environ);)
5897 IA64_ONLY(execve("/bin/sh", (char* const*)argv, environ);)
5898
5899 // execve failed
5900 _exit(-1);
5901
5902 } else {
5903 // copied from J2SE ..._waitForProcessExit() in UNIXProcess_md.c; we don't
5904 // care about the actual exit code, for now.
5905
5906 int status;
5907
5908 // Wait for the child process to exit. This returns immediately if
5909 // the child has already exited. */
5910 while (waitpid(pid, &status, 0) < 0) {
5911 switch (errno) {
5912 case ECHILD: return 0;
5913 case EINTR: break;
5914 default: return -1;
5915 }
5916 }
5917
5918 if (WIFEXITED(status)) {
5919 // The child exited normally; get its exit code.
5920 return WEXITSTATUS(status);
5921 } else if (WIFSIGNALED(status)) {
5922 // The child exited because of a signal
5923 // The best value to return is 0x80 + signal number,
5924 // because that is what all Unix shells do, and because
5925 // it allows callers to distinguish between process exit and
5926 // process death by signal.
5927 return 0x80 + WTERMSIG(status);
5928 } else {
5929 // Unknown exit code; pass it through
5930 return status;
5931 }
5932 }
5933 }
5934
5935 // is_headless_jre()
5936 //
5937 // Test for the existence of xawt/libmawt.so or libawt_xawt.so
5938 // in order to report if we are running in a headless jre
5939 //
5940 // Since JDK8 xawt/libmawt.so was moved into the same directory
5941 // as libawt.so, and renamed libawt_xawt.so
5942 //
5943 bool os::is_headless_jre() {
5944 struct stat statbuf;
5945 char buf[MAXPATHLEN];
5946 char libmawtpath[MAXPATHLEN];
5947 const char *xawtstr = "/xawt/libmawt.so";
5948 const char *new_xawtstr = "/libawt_xawt.so";
5949 char *p;
5950
5951 // Get path to libjvm.so
5952 os::jvm_path(buf, sizeof(buf));
5953
5954 // Get rid of libjvm.so
5955 p = strrchr(buf, '/');
5956 if (p == NULL) return false;
5957 else *p = '\0';
5958
5959 // Get rid of client or server
5960 p = strrchr(buf, '/');
5961 if (p == NULL) return false;
5962 else *p = '\0';
5963
5964 // check xawt/libmawt.so
5965 strcpy(libmawtpath, buf);
5966 strcat(libmawtpath, xawtstr);
5967 if (::stat(libmawtpath, &statbuf) == 0) return false;
5968
5969 // check libawt_xawt.so
5970 strcpy(libmawtpath, buf);
5971 strcat(libmawtpath, new_xawtstr);
5972 if (::stat(libmawtpath, &statbuf) == 0) return false;
5973
5974 return true;
5975 }
5976
5977 // Get the default path to the core file
5978 // Returns the length of the string
5979 int os::get_core_path(char* buffer, size_t bufferSize) {
5980 const char* p = get_current_directory(buffer, bufferSize);
5981
5982 if (p == NULL) {
5983 assert(p != NULL, "failed to get current directory");
5984 return 0;
5985 }
5986
5987 return strlen(buffer);
5988 }
5989
5990 #ifdef JAVASE_EMBEDDED
5991 //
5992 // A thread to watch the '/dev/mem_notify' device, which will tell us when the OS is running low on memory.
5993 //
5994 MemNotifyThread* MemNotifyThread::_memnotify_thread = NULL;
5995
5996 // ctor
5997 //
5998 MemNotifyThread::MemNotifyThread(int fd): Thread() {
5999 assert(memnotify_thread() == NULL, "we can only allocate one MemNotifyThread");
6000 _fd = fd;
6001
6002 if (os::create_thread(this, os::os_thread)) {
6003 _memnotify_thread = this;
6004 os::set_priority(this, NearMaxPriority);
6005 os::start_thread(this);
6006 }
6007 }
6008
6009 // Where all the work gets done
6010 //
6011 void MemNotifyThread::run() {
6012 assert(this == memnotify_thread(), "expected the singleton MemNotifyThread");
6013
6014 // Set up the select arguments
6015 fd_set rfds;
6016 if (_fd != -1) {
6017 FD_ZERO(&rfds);
6018 FD_SET(_fd, &rfds);
6019 }
6020
6021 // Now wait for the mem_notify device to wake up
6022 while (1) {
6023 // Wait for the mem_notify device to signal us..
6024 int rc = select(_fd+1, _fd != -1 ? &rfds : NULL, NULL, NULL, NULL);
6025 if (rc == -1) {
6026 perror("select!\n");
6027 break;
6028 } else if (rc) {
6029 //ssize_t free_before = os::available_memory();
6030 //tty->print ("Notified: Free: %dK \n",os::available_memory()/1024);
6031
6032 // The kernel is telling us there is not much memory left...
6033 // try to do something about that
6034
6035 // If we are not already in a GC, try one.
6036 if (!Universe::heap()->is_gc_active()) {
6037 Universe::heap()->collect(GCCause::_allocation_failure);
6038
6039 //ssize_t free_after = os::available_memory();
6040 //tty->print ("Post-Notify: Free: %dK\n",free_after/1024);
6041 //tty->print ("GC freed: %dK\n", (free_after - free_before)/1024);
6042 }
6043 // We might want to do something like the following if we find the GC's are not helping...
6044 // Universe::heap()->size_policy()->set_gc_time_limit_exceeded(true);
6045 }
6046 }
6047 }
6048
6049 //
6050 // See if the /dev/mem_notify device exists, and if so, start a thread to monitor it.
6051 //
6052 void MemNotifyThread::start() {
6053 int fd;
6054 fd = open ("/dev/mem_notify", O_RDONLY, 0);
6055 if (fd < 0) {
6056 return;
6057 }
6058
6059 if (memnotify_thread() == NULL) {
6060 new MemNotifyThread(fd);
6061 }
6062 }
6063
6064 #endif // JAVASE_EMBEDDED
6065
6066
6067 /////////////// Unit tests ///////////////
6068
6069 #ifndef PRODUCT
6070
6071 #define test_log(...) \
6072 do {\
6073 if (VerboseInternalVMTests) { \
6074 tty->print_cr(__VA_ARGS__); \
6075 tty->flush(); \
6076 }\
6077 } while (false)
6078
6079 class TestReserveMemorySpecial : AllStatic {
6080 public:
6081 static void small_page_write(void* addr, size_t size) {
6082 size_t page_size = os::vm_page_size();
6083
6084 char* end = (char*)addr + size;
6085 for (char* p = (char*)addr; p < end; p += page_size) {
6086 *p = 1;
6087 }
6088 }
6089
6090 static void test_reserve_memory_special_huge_tlbfs_only(size_t size) {
6091 if (!UseHugeTLBFS) {
6092 return;
6093 }
6094
6095 test_log("test_reserve_memory_special_huge_tlbfs_only(" SIZE_FORMAT ")", size);
6096
6097 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_only(size, NULL, false);
6098
6099 if (addr != NULL) {
6100 small_page_write(addr, size);
6101
6102 os::Linux::release_memory_special_huge_tlbfs(addr, size);
6103 }
6104 }
6105
6106 static void test_reserve_memory_special_huge_tlbfs_only() {
6107 if (!UseHugeTLBFS) {
6108 return;
6109 }
6110
6111 size_t lp = os::large_page_size();
6112
6113 for (size_t size = lp; size <= lp * 10; size += lp) {
6114 test_reserve_memory_special_huge_tlbfs_only(size);
6115 }
6116 }
6117
6118 static void test_reserve_memory_special_huge_tlbfs_mixed(size_t size, size_t alignment) {
6119 if (!UseHugeTLBFS) {
6120 return;
6121 }
6122
6123 test_log("test_reserve_memory_special_huge_tlbfs_mixed(" SIZE_FORMAT ", " SIZE_FORMAT ")",
6124 size, alignment);
6125
6126 assert(size >= os::large_page_size(), "Incorrect input to test");
6127
6128 char* addr = os::Linux::reserve_memory_special_huge_tlbfs_mixed(size, alignment, NULL, false);
6129
6130 if (addr != NULL) {
6131 small_page_write(addr, size);
6132
6133 os::Linux::release_memory_special_huge_tlbfs(addr, size);
6134 }
6135 }
6136
6137 static void test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(size_t size) {
6138 size_t lp = os::large_page_size();
6139 size_t ag = os::vm_allocation_granularity();
6140
6141 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) {
6142 test_reserve_memory_special_huge_tlbfs_mixed(size, alignment);
6143 }
6144 }
6145
6146 static void test_reserve_memory_special_huge_tlbfs_mixed() {
6147 size_t lp = os::large_page_size();
6148 size_t ag = os::vm_allocation_granularity();
6149
6150 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp);
6151 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + ag);
6152 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp + lp / 2);
6153 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2);
6154 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 + ag);
6155 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 - ag);
6156 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 2 + lp / 2);
6157 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10);
6158 test_reserve_memory_special_huge_tlbfs_mixed_all_alignments(lp * 10 + lp / 2);
6159 }
6160
6161 static void test_reserve_memory_special_huge_tlbfs() {
6162 if (!UseHugeTLBFS) {
6163 return;
6164 }
6165
6166 test_reserve_memory_special_huge_tlbfs_only();
6167 test_reserve_memory_special_huge_tlbfs_mixed();
6168 }
6169
6170 static void test_reserve_memory_special_shm(size_t size, size_t alignment) {
6171 if (!UseSHM) {
6172 return;
6173 }
6174
6175 test_log("test_reserve_memory_special_shm(" SIZE_FORMAT ", " SIZE_FORMAT ")", size, alignment);
6176
6177 char* addr = os::Linux::reserve_memory_special_shm(size, alignment, NULL, false);
6178
6179 if (addr != NULL) {
6180 assert(is_ptr_aligned(addr, alignment), "Check");
6181 assert(is_ptr_aligned(addr, os::large_page_size()), "Check");
6182
6183 small_page_write(addr, size);
6184
6185 os::Linux::release_memory_special_shm(addr, size);
6186 }
6187 }
6188
6189 static void test_reserve_memory_special_shm() {
6190 size_t lp = os::large_page_size();
6191 size_t ag = os::vm_allocation_granularity();
6192
6193 for (size_t size = ag; size < lp * 3; size += ag) {
6194 for (size_t alignment = ag; is_size_aligned(size, alignment); alignment *= 2) {
6195 test_reserve_memory_special_shm(size, alignment);
6196 }
6197 }
6198 }
6199
6200 static void test() {
6201 test_reserve_memory_special_huge_tlbfs();
6202 test_reserve_memory_special_shm();
6203 }
6204 };
6205
6206 void TestReserveMemorySpecial_test() {
6207 TestReserveMemorySpecial::test();
6208 }
6209
6210 #endif