1 /*
2 * Copyright (c) 1997, 2018, 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 #include "precompiled.hpp"
26 #include "jvm.h"
27 #include "classfile/classLoader.hpp"
28 #include "classfile/javaClasses.hpp"
29 #include "classfile/moduleEntry.hpp"
30 #include "classfile/systemDictionary.hpp"
31 #include "classfile/vmSymbols.hpp"
32 #include "code/codeCache.hpp"
33 #include "code/icBuffer.hpp"
34 #include "code/vtableStubs.hpp"
35 #include "gc/shared/vmGCOperations.hpp"
36 #include "logging/log.hpp"
37 #include "interpreter/interpreter.hpp"
38 #include "logging/log.hpp"
39 #include "logging/logStream.hpp"
40 #include "memory/allocation.inline.hpp"
41 #ifdef ASSERT
42 #include "memory/guardedMemory.hpp"
43 #endif
44 #include "memory/resourceArea.hpp"
45 #include "oops/oop.inline.hpp"
46 #include "prims/jvm_misc.hpp"
47 #include "prims/privilegedStack.hpp"
48 #include "runtime/arguments.hpp"
49 #include "runtime/atomic.hpp"
50 #include "runtime/frame.inline.hpp"
51 #include "runtime/interfaceSupport.inline.hpp"
52 #include "runtime/java.hpp"
53 #include "runtime/javaCalls.hpp"
54 #include "runtime/mutexLocker.hpp"
55 #include "runtime/os.inline.hpp"
56 #include "runtime/sharedRuntime.hpp"
57 #include "runtime/stubRoutines.hpp"
58 #include "runtime/thread.inline.hpp"
59 #include "runtime/threadSMR.hpp"
60 #include "runtime/vm_version.hpp"
61 #include "services/attachListener.hpp"
62 #include "services/mallocTracker.hpp"
63 #include "services/memTracker.hpp"
64 #include "services/nmtCommon.hpp"
65 #include "services/threadService.hpp"
66 #include "utilities/align.hpp"
67 #include "utilities/defaultStream.hpp"
68 #include "utilities/events.hpp"
69
70 # include <signal.h>
71 # include <errno.h>
72
73 OSThread* os::_starting_thread = NULL;
74 address os::_polling_page = NULL;
75 volatile int32_t* os::_mem_serialize_page = NULL;
76 uintptr_t os::_serialize_page_mask = 0;
77 volatile unsigned int os::_rand_seed = 1;
78 int os::_processor_count = 0;
79 int os::_initial_active_processor_count = 0;
80 size_t os::_page_sizes[os::page_sizes_max];
81
82 #ifndef PRODUCT
83 julong os::num_mallocs = 0; // # of calls to malloc/realloc
84 julong os::alloc_bytes = 0; // # of bytes allocated
85 julong os::num_frees = 0; // # of calls to free
86 julong os::free_bytes = 0; // # of bytes freed
87 #endif
88
89 static size_t cur_malloc_words = 0; // current size for MallocMaxTestWords
90
91 void os_init_globals() {
92 // Called from init_globals().
93 // See Threads::create_vm() in thread.cpp, and init.cpp.
94 os::init_globals();
95 }
96
97 static time_t get_timezone(const struct tm* time_struct) {
98 #if defined(_ALLBSD_SOURCE)
99 return time_struct->tm_gmtoff;
100 #elif defined(_WINDOWS)
101 long zone;
102 _get_timezone(&zone);
103 return static_cast<time_t>(zone);
104 #else
105 return timezone;
106 #endif
107 }
108
109 int os::snprintf(char* buf, size_t len, const char* fmt, ...) {
110 va_list args;
111 va_start(args, fmt);
112 int result = os::vsnprintf(buf, len, fmt, args);
113 va_end(args);
114 return result;
115 }
116
117 // Fill in buffer with current local time as an ISO-8601 string.
118 // E.g., yyyy-mm-ddThh:mm:ss-zzzz.
119 // Returns buffer, or NULL if it failed.
120 // This would mostly be a call to
121 // strftime(...., "%Y-%m-%d" "T" "%H:%M:%S" "%z", ....)
122 // except that on Windows the %z behaves badly, so we do it ourselves.
123 // Also, people wanted milliseconds on there,
124 // and strftime doesn't do milliseconds.
125 char* os::iso8601_time(char* buffer, size_t buffer_length, bool utc) {
126 // Output will be of the form "YYYY-MM-DDThh:mm:ss.mmm+zzzz\0"
127 // 1 2
128 // 12345678901234567890123456789
129 // format string: "%04d-%02d-%02dT%02d:%02d:%02d.%03d%c%02d%02d"
130 static const size_t needed_buffer = 29;
131
132 // Sanity check the arguments
133 if (buffer == NULL) {
134 assert(false, "NULL buffer");
135 return NULL;
136 }
137 if (buffer_length < needed_buffer) {
138 assert(false, "buffer_length too small");
139 return NULL;
140 }
141 // Get the current time
142 jlong milliseconds_since_19700101 = javaTimeMillis();
143 const int milliseconds_per_microsecond = 1000;
144 const time_t seconds_since_19700101 =
145 milliseconds_since_19700101 / milliseconds_per_microsecond;
146 const int milliseconds_after_second =
147 milliseconds_since_19700101 % milliseconds_per_microsecond;
148 // Convert the time value to a tm and timezone variable
149 struct tm time_struct;
150 if (utc) {
151 if (gmtime_pd(&seconds_since_19700101, &time_struct) == NULL) {
152 assert(false, "Failed gmtime_pd");
153 return NULL;
154 }
155 } else {
156 if (localtime_pd(&seconds_since_19700101, &time_struct) == NULL) {
157 assert(false, "Failed localtime_pd");
158 return NULL;
159 }
160 }
161 const time_t zone = get_timezone(&time_struct);
162
163 // If daylight savings time is in effect,
164 // we are 1 hour East of our time zone
165 const time_t seconds_per_minute = 60;
166 const time_t minutes_per_hour = 60;
167 const time_t seconds_per_hour = seconds_per_minute * minutes_per_hour;
168 time_t UTC_to_local = zone;
169 if (time_struct.tm_isdst > 0) {
170 UTC_to_local = UTC_to_local - seconds_per_hour;
171 }
172
173 // No offset when dealing with UTC
174 if (utc) {
175 UTC_to_local = 0;
176 }
177
178 // Compute the time zone offset.
179 // localtime_pd() sets timezone to the difference (in seconds)
180 // between UTC and and local time.
181 // ISO 8601 says we need the difference between local time and UTC,
182 // we change the sign of the localtime_pd() result.
183 const time_t local_to_UTC = -(UTC_to_local);
184 // Then we have to figure out if if we are ahead (+) or behind (-) UTC.
185 char sign_local_to_UTC = '+';
186 time_t abs_local_to_UTC = local_to_UTC;
187 if (local_to_UTC < 0) {
188 sign_local_to_UTC = '-';
189 abs_local_to_UTC = -(abs_local_to_UTC);
190 }
191 // Convert time zone offset seconds to hours and minutes.
192 const time_t zone_hours = (abs_local_to_UTC / seconds_per_hour);
193 const time_t zone_min =
194 ((abs_local_to_UTC % seconds_per_hour) / seconds_per_minute);
195
196 // Print an ISO 8601 date and time stamp into the buffer
197 const int year = 1900 + time_struct.tm_year;
198 const int month = 1 + time_struct.tm_mon;
199 const int printed = jio_snprintf(buffer, buffer_length,
200 "%04d-%02d-%02dT%02d:%02d:%02d.%03d%c%02d%02d",
201 year,
202 month,
203 time_struct.tm_mday,
204 time_struct.tm_hour,
205 time_struct.tm_min,
206 time_struct.tm_sec,
207 milliseconds_after_second,
208 sign_local_to_UTC,
209 zone_hours,
210 zone_min);
211 if (printed == 0) {
212 assert(false, "Failed jio_printf");
213 return NULL;
214 }
215 return buffer;
216 }
217
218 OSReturn os::set_priority(Thread* thread, ThreadPriority p) {
219 debug_only(Thread::check_for_dangling_thread_pointer(thread);)
220
221 if (p >= MinPriority && p <= MaxPriority) {
222 int priority = java_to_os_priority[p];
223 return set_native_priority(thread, priority);
224 } else {
225 assert(false, "Should not happen");
226 return OS_ERR;
227 }
228 }
229
230 // The mapping from OS priority back to Java priority may be inexact because
231 // Java priorities can map M:1 with native priorities. If you want the definite
232 // Java priority then use JavaThread::java_priority()
233 OSReturn os::get_priority(const Thread* const thread, ThreadPriority& priority) {
234 int p;
235 int os_prio;
236 OSReturn ret = get_native_priority(thread, &os_prio);
237 if (ret != OS_OK) return ret;
238
239 if (java_to_os_priority[MaxPriority] > java_to_os_priority[MinPriority]) {
240 for (p = MaxPriority; p > MinPriority && java_to_os_priority[p] > os_prio; p--) ;
241 } else {
242 // niceness values are in reverse order
243 for (p = MaxPriority; p > MinPriority && java_to_os_priority[p] < os_prio; p--) ;
244 }
245 priority = (ThreadPriority)p;
246 return OS_OK;
247 }
248
249 bool os::dll_build_name(char* buffer, size_t size, const char* fname) {
250 int n = jio_snprintf(buffer, size, "%s%s%s", JNI_LIB_PREFIX, fname, JNI_LIB_SUFFIX);
251 return (n != -1);
252 }
253
254 #if !defined(LINUX) && !defined(_WINDOWS)
255 bool os::committed_in_range(address start, size_t size, address& committed_start, size_t& committed_size) {
256 committed_start = start;
257 committed_size = size;
258 return true;
259 }
260 #endif
261
262 // Helper for dll_locate_lib.
263 // Pass buffer and printbuffer as we already printed the path to buffer
264 // when we called get_current_directory. This way we avoid another buffer
265 // of size MAX_PATH.
266 static bool conc_path_file_and_check(char *buffer, char *printbuffer, size_t printbuflen,
267 const char* pname, char lastchar, const char* fname) {
268
269 // Concatenate path and file name, but don't print double path separators.
270 const char *filesep = (WINDOWS_ONLY(lastchar == ':' ||) lastchar == os::file_separator()[0]) ?
271 "" : os::file_separator();
272 int ret = jio_snprintf(printbuffer, printbuflen, "%s%s%s", pname, filesep, fname);
273 // Check whether file exists.
274 if (ret != -1) {
275 struct stat statbuf;
276 return os::stat(buffer, &statbuf) == 0;
277 }
278 return false;
279 }
280
281 bool os::dll_locate_lib(char *buffer, size_t buflen,
282 const char* pname, const char* fname) {
283 bool retval = false;
284
285 size_t fullfnamelen = strlen(JNI_LIB_PREFIX) + strlen(fname) + strlen(JNI_LIB_SUFFIX);
286 char* fullfname = (char*)NEW_C_HEAP_ARRAY(char, fullfnamelen + 1, mtInternal);
287 if (dll_build_name(fullfname, fullfnamelen + 1, fname)) {
288 const size_t pnamelen = pname ? strlen(pname) : 0;
289
290 if (pnamelen == 0) {
291 // If no path given, use current working directory.
292 const char* p = get_current_directory(buffer, buflen);
293 if (p != NULL) {
294 const size_t plen = strlen(buffer);
295 const char lastchar = buffer[plen - 1];
296 retval = conc_path_file_and_check(buffer, &buffer[plen], buflen - plen,
297 "", lastchar, fullfname);
298 }
299 } else if (strchr(pname, *os::path_separator()) != NULL) {
300 // A list of paths. Search for the path that contains the library.
301 int n;
302 char** pelements = split_path(pname, &n);
303 if (pelements != NULL) {
304 for (int i = 0; i < n; i++) {
305 char* path = pelements[i];
306 // Really shouldn't be NULL, but check can't hurt.
307 size_t plen = (path == NULL) ? 0 : strlen(path);
308 if (plen == 0) {
309 continue; // Skip the empty path values.
310 }
311 const char lastchar = path[plen - 1];
312 retval = conc_path_file_and_check(buffer, buffer, buflen, path, lastchar, fullfname);
313 if (retval) break;
314 }
315 // Release the storage allocated by split_path.
316 for (int i = 0; i < n; i++) {
317 if (pelements[i] != NULL) {
318 FREE_C_HEAP_ARRAY(char, pelements[i]);
319 }
320 }
321 FREE_C_HEAP_ARRAY(char*, pelements);
322 }
323 } else {
324 // A definite path.
325 const char lastchar = pname[pnamelen-1];
326 retval = conc_path_file_and_check(buffer, buffer, buflen, pname, lastchar, fullfname);
327 }
328 }
329
330 FREE_C_HEAP_ARRAY(char*, fullfname);
331 return retval;
332 }
333
334 // --------------------- sun.misc.Signal (optional) ---------------------
335
336
337 // SIGBREAK is sent by the keyboard to query the VM state
338 #ifndef SIGBREAK
339 #define SIGBREAK SIGQUIT
340 #endif
341
342 // sigexitnum_pd is a platform-specific special signal used for terminating the Signal thread.
343
344
345 static void signal_thread_entry(JavaThread* thread, TRAPS) {
346 os::set_priority(thread, NearMaxPriority);
347 while (true) {
348 int sig;
349 {
350 // FIXME : Currently we have not decided what should be the status
351 // for this java thread blocked here. Once we decide about
352 // that we should fix this.
353 sig = os::signal_wait();
354 }
355 if (sig == os::sigexitnum_pd()) {
356 // Terminate the signal thread
357 return;
358 }
359
360 switch (sig) {
361 case SIGBREAK: {
362 // Check if the signal is a trigger to start the Attach Listener - in that
363 // case don't print stack traces.
364 if (!DisableAttachMechanism && AttachListener::is_init_trigger()) {
365 continue;
366 }
367 // Print stack traces
368 // Any SIGBREAK operations added here should make sure to flush
369 // the output stream (e.g. tty->flush()) after output. See 4803766.
370 // Each module also prints an extra carriage return after its output.
371 VM_PrintThreads op;
372 VMThread::execute(&op);
373 VM_PrintJNI jni_op;
374 VMThread::execute(&jni_op);
375 VM_FindDeadlocks op1(tty);
376 VMThread::execute(&op1);
377 Universe::print_heap_at_SIGBREAK();
378 if (PrintClassHistogram) {
379 VM_GC_HeapInspection op1(tty, true /* force full GC before heap inspection */);
380 VMThread::execute(&op1);
381 }
382 if (JvmtiExport::should_post_data_dump()) {
383 JvmtiExport::post_data_dump();
384 }
385 break;
386 }
387 default: {
388 // Dispatch the signal to java
389 HandleMark hm(THREAD);
390 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_misc_Signal(), THREAD);
391 if (klass != NULL) {
392 JavaValue result(T_VOID);
393 JavaCallArguments args;
394 args.push_int(sig);
395 JavaCalls::call_static(
396 &result,
397 klass,
398 vmSymbols::dispatch_name(),
399 vmSymbols::int_void_signature(),
400 &args,
401 THREAD
402 );
403 }
404 if (HAS_PENDING_EXCEPTION) {
405 // tty is initialized early so we don't expect it to be null, but
406 // if it is we can't risk doing an initialization that might
407 // trigger additional out-of-memory conditions
408 if (tty != NULL) {
409 char klass_name[256];
410 char tmp_sig_name[16];
411 const char* sig_name = "UNKNOWN";
412 InstanceKlass::cast(PENDING_EXCEPTION->klass())->
413 name()->as_klass_external_name(klass_name, 256);
414 if (os::exception_name(sig, tmp_sig_name, 16) != NULL)
415 sig_name = tmp_sig_name;
416 warning("Exception %s occurred dispatching signal %s to handler"
417 "- the VM may need to be forcibly terminated",
418 klass_name, sig_name );
419 }
420 CLEAR_PENDING_EXCEPTION;
421 }
422 }
423 }
424 }
425 }
426
427 void os::init_before_ergo() {
428 initialize_initial_active_processor_count();
429 // We need to initialize large page support here because ergonomics takes some
430 // decisions depending on large page support and the calculated large page size.
431 large_page_init();
432
433 // We need to adapt the configured number of stack protection pages given
434 // in 4K pages to the actual os page size. We must do this before setting
435 // up minimal stack sizes etc. in os::init_2().
436 JavaThread::set_stack_red_zone_size (align_up(StackRedPages * 4 * K, vm_page_size()));
437 JavaThread::set_stack_yellow_zone_size (align_up(StackYellowPages * 4 * K, vm_page_size()));
438 JavaThread::set_stack_reserved_zone_size(align_up(StackReservedPages * 4 * K, vm_page_size()));
439 JavaThread::set_stack_shadow_zone_size (align_up(StackShadowPages * 4 * K, vm_page_size()));
440
441 // VM version initialization identifies some characteristics of the
442 // platform that are used during ergonomic decisions.
443 VM_Version::init_before_ergo();
444 }
445
446 void os::initialize_jdk_signal_support(TRAPS) {
447 if (!ReduceSignalUsage) {
448 // Setup JavaThread for processing signals
449 const char thread_name[] = "Signal Dispatcher";
450 Handle string = java_lang_String::create_from_str(thread_name, CHECK);
451
452 // Initialize thread_oop to put it into the system threadGroup
453 Handle thread_group (THREAD, Universe::system_thread_group());
454 Handle thread_oop = JavaCalls::construct_new_instance(SystemDictionary::Thread_klass(),
455 vmSymbols::threadgroup_string_void_signature(),
456 thread_group,
457 string,
458 CHECK);
459
460 Klass* group = SystemDictionary::ThreadGroup_klass();
461 JavaValue result(T_VOID);
462 JavaCalls::call_special(&result,
463 thread_group,
464 group,
465 vmSymbols::add_method_name(),
466 vmSymbols::thread_void_signature(),
467 thread_oop,
468 CHECK);
469
470 { MutexLocker mu(Threads_lock);
471 JavaThread* signal_thread = new JavaThread(&signal_thread_entry);
472
473 // At this point it may be possible that no osthread was created for the
474 // JavaThread due to lack of memory. We would have to throw an exception
475 // in that case. However, since this must work and we do not allow
476 // exceptions anyway, check and abort if this fails.
477 if (signal_thread == NULL || signal_thread->osthread() == NULL) {
478 vm_exit_during_initialization("java.lang.OutOfMemoryError",
479 os::native_thread_creation_failed_msg());
480 }
481
482 java_lang_Thread::set_thread(thread_oop(), signal_thread);
483 java_lang_Thread::set_priority(thread_oop(), NearMaxPriority);
484 java_lang_Thread::set_daemon(thread_oop());
485
486 signal_thread->set_threadObj(thread_oop());
487 Threads::add(signal_thread);
488 Thread::start(signal_thread);
489 }
490 // Handle ^BREAK
491 os::signal(SIGBREAK, os::user_handler());
492 }
493 }
494
495
496 void os::terminate_signal_thread() {
497 if (!ReduceSignalUsage)
498 signal_notify(sigexitnum_pd());
499 }
500
501
502 // --------------------- loading libraries ---------------------
503
504 typedef jint (JNICALL *JNI_OnLoad_t)(JavaVM *, void *);
505 extern struct JavaVM_ main_vm;
506
507 static void* _native_java_library = NULL;
508
509 void* os::native_java_library() {
510 if (_native_java_library == NULL) {
511 char buffer[JVM_MAXPATHLEN];
512 char ebuf[1024];
513
514 // Try to load verify dll first. In 1.3 java dll depends on it and is not
515 // always able to find it when the loading executable is outside the JDK.
516 // In order to keep working with 1.2 we ignore any loading errors.
517 if (dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
518 "verify")) {
519 dll_load(buffer, ebuf, sizeof(ebuf));
520 }
521
522 // Load java dll
523 if (dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
524 "java")) {
525 _native_java_library = dll_load(buffer, ebuf, sizeof(ebuf));
526 }
527 if (_native_java_library == NULL) {
528 vm_exit_during_initialization("Unable to load native library", ebuf);
529 }
530
531 #if defined(__OpenBSD__)
532 // Work-around OpenBSD's lack of $ORIGIN support by pre-loading libnet.so
533 // ignore errors
534 if (dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
535 "net")) {
536 dll_load(buffer, ebuf, sizeof(ebuf));
537 }
538 #endif
539 }
540 return _native_java_library;
541 }
542
543 /*
544 * Support for finding Agent_On(Un)Load/Attach<_lib_name> if it exists.
545 * If check_lib == true then we are looking for an
546 * Agent_OnLoad_lib_name or Agent_OnAttach_lib_name function to determine if
547 * this library is statically linked into the image.
548 * If check_lib == false then we will look for the appropriate symbol in the
549 * executable if agent_lib->is_static_lib() == true or in the shared library
550 * referenced by 'handle'.
551 */
552 void* os::find_agent_function(AgentLibrary *agent_lib, bool check_lib,
553 const char *syms[], size_t syms_len) {
554 assert(agent_lib != NULL, "sanity check");
555 const char *lib_name;
556 void *handle = agent_lib->os_lib();
557 void *entryName = NULL;
558 char *agent_function_name;
559 size_t i;
560
561 // If checking then use the agent name otherwise test is_static_lib() to
562 // see how to process this lookup
563 lib_name = ((check_lib || agent_lib->is_static_lib()) ? agent_lib->name() : NULL);
564 for (i = 0; i < syms_len; i++) {
565 agent_function_name = build_agent_function_name(syms[i], lib_name, agent_lib->is_absolute_path());
566 if (agent_function_name == NULL) {
567 break;
568 }
569 entryName = dll_lookup(handle, agent_function_name);
570 FREE_C_HEAP_ARRAY(char, agent_function_name);
571 if (entryName != NULL) {
572 break;
573 }
574 }
575 return entryName;
576 }
577
578 // See if the passed in agent is statically linked into the VM image.
579 bool os::find_builtin_agent(AgentLibrary *agent_lib, const char *syms[],
580 size_t syms_len) {
581 void *ret;
582 void *proc_handle;
583 void *save_handle;
584
585 assert(agent_lib != NULL, "sanity check");
586 if (agent_lib->name() == NULL) {
587 return false;
588 }
589 proc_handle = get_default_process_handle();
590 // Check for Agent_OnLoad/Attach_lib_name function
591 save_handle = agent_lib->os_lib();
592 // We want to look in this process' symbol table.
593 agent_lib->set_os_lib(proc_handle);
594 ret = find_agent_function(agent_lib, true, syms, syms_len);
595 if (ret != NULL) {
596 // Found an entry point like Agent_OnLoad_lib_name so we have a static agent
597 agent_lib->set_valid();
598 agent_lib->set_static_lib(true);
599 return true;
600 }
601 agent_lib->set_os_lib(save_handle);
602 return false;
603 }
604
605 // --------------------- heap allocation utilities ---------------------
606
607 char *os::strdup(const char *str, MEMFLAGS flags) {
608 size_t size = strlen(str);
609 char *dup_str = (char *)malloc(size + 1, flags);
610 if (dup_str == NULL) return NULL;
611 strcpy(dup_str, str);
612 return dup_str;
613 }
614
615 char* os::strdup_check_oom(const char* str, MEMFLAGS flags) {
616 char* p = os::strdup(str, flags);
617 if (p == NULL) {
618 vm_exit_out_of_memory(strlen(str) + 1, OOM_MALLOC_ERROR, "os::strdup_check_oom");
619 }
620 return p;
621 }
622
623
624 #define paranoid 0 /* only set to 1 if you suspect checking code has bug */
625
626 #ifdef ASSERT
627
628 static void verify_memory(void* ptr) {
629 GuardedMemory guarded(ptr);
630 if (!guarded.verify_guards()) {
631 LogTarget(Warning, malloc, free) lt;
632 ResourceMark rm;
633 LogStream ls(lt);
634 ls.print_cr("## nof_mallocs = " UINT64_FORMAT ", nof_frees = " UINT64_FORMAT, os::num_mallocs, os::num_frees);
635 ls.print_cr("## memory stomp:");
636 guarded.print_on(&ls);
637 fatal("memory stomping error");
638 }
639 }
640
641 #endif
642
643 //
644 // This function supports testing of the malloc out of memory
645 // condition without really running the system out of memory.
646 //
647 static bool has_reached_max_malloc_test_peak(size_t alloc_size) {
648 if (MallocMaxTestWords > 0) {
649 size_t words = (alloc_size / BytesPerWord);
650
651 if ((cur_malloc_words + words) > MallocMaxTestWords) {
652 return true;
653 }
654 Atomic::add(words, &cur_malloc_words);
655 }
656 return false;
657 }
658
659 void* os::malloc(size_t size, MEMFLAGS flags) {
660 return os::malloc(size, flags, CALLER_PC);
661 }
662
663 void* os::malloc(size_t size, MEMFLAGS memflags, const NativeCallStack& stack) {
664 NOT_PRODUCT(inc_stat_counter(&num_mallocs, 1));
665 NOT_PRODUCT(inc_stat_counter(&alloc_bytes, size));
666
667 // Since os::malloc can be called when the libjvm.{dll,so} is
668 // first loaded and we don't have a thread yet we must accept NULL also here.
669 assert(!os::ThreadCrashProtection::is_crash_protected(Thread::current_or_null()),
670 "malloc() not allowed when crash protection is set");
671
672 if (size == 0) {
673 // return a valid pointer if size is zero
674 // if NULL is returned the calling functions assume out of memory.
675 size = 1;
676 }
677
678 // NMT support
679 NMT_TrackingLevel level = MemTracker::tracking_level();
680 size_t nmt_header_size = MemTracker::malloc_header_size(level);
681
682 #ifndef ASSERT
683 const size_t alloc_size = size + nmt_header_size;
684 #else
685 const size_t alloc_size = GuardedMemory::get_total_size(size + nmt_header_size);
686 if (size + nmt_header_size > alloc_size) { // Check for rollover.
687 return NULL;
688 }
689 #endif
690
691 // For the test flag -XX:MallocMaxTestWords
692 if (has_reached_max_malloc_test_peak(size)) {
693 return NULL;
694 }
695
696 u_char* ptr;
697 ptr = (u_char*)::malloc(alloc_size);
698
699 #ifdef ASSERT
700 if (ptr == NULL) {
701 return NULL;
702 }
703 // Wrap memory with guard
704 GuardedMemory guarded(ptr, size + nmt_header_size);
705 ptr = guarded.get_user_ptr();
706 #endif
707 if ((intptr_t)ptr == (intptr_t)MallocCatchPtr) {
708 log_warning(malloc, free)("os::malloc caught, " SIZE_FORMAT " bytes --> " PTR_FORMAT, size, p2i(ptr));
709 breakpoint();
710 }
711 debug_only(if (paranoid) verify_memory(ptr));
712
713 // we do not track guard memory
714 return MemTracker::record_malloc((address)ptr, size, memflags, stack, level);
715 }
716
717 void* os::realloc(void *memblock, size_t size, MEMFLAGS flags) {
718 return os::realloc(memblock, size, flags, CALLER_PC);
719 }
720
721 void* os::realloc(void *memblock, size_t size, MEMFLAGS memflags, const NativeCallStack& stack) {
722
723 // For the test flag -XX:MallocMaxTestWords
724 if (has_reached_max_malloc_test_peak(size)) {
725 return NULL;
726 }
727
728 if (size == 0) {
729 // return a valid pointer if size is zero
730 // if NULL is returned the calling functions assume out of memory.
731 size = 1;
732 }
733
734 #ifndef ASSERT
735 NOT_PRODUCT(inc_stat_counter(&num_mallocs, 1));
736 NOT_PRODUCT(inc_stat_counter(&alloc_bytes, size));
737 // NMT support
738 void* membase = MemTracker::record_free(memblock);
739 NMT_TrackingLevel level = MemTracker::tracking_level();
740 size_t nmt_header_size = MemTracker::malloc_header_size(level);
741 void* ptr = ::realloc(membase, size + nmt_header_size);
742 return MemTracker::record_malloc(ptr, size, memflags, stack, level);
743 #else
744 if (memblock == NULL) {
745 return os::malloc(size, memflags, stack);
746 }
747 if ((intptr_t)memblock == (intptr_t)MallocCatchPtr) {
748 log_warning(malloc, free)("os::realloc caught " PTR_FORMAT, p2i(memblock));
749 breakpoint();
750 }
751 // NMT support
752 void* membase = MemTracker::malloc_base(memblock);
753 verify_memory(membase);
754 // always move the block
755 void* ptr = os::malloc(size, memflags, stack);
756 // Copy to new memory if malloc didn't fail
757 if (ptr != NULL ) {
758 GuardedMemory guarded(MemTracker::malloc_base(memblock));
759 // Guard's user data contains NMT header
760 size_t memblock_size = guarded.get_user_size() - MemTracker::malloc_header_size(memblock);
761 memcpy(ptr, memblock, MIN2(size, memblock_size));
762 if (paranoid) verify_memory(MemTracker::malloc_base(ptr));
763 if ((intptr_t)ptr == (intptr_t)MallocCatchPtr) {
764 log_warning(malloc, free)("os::realloc caught, " SIZE_FORMAT " bytes --> " PTR_FORMAT, size, p2i(ptr));
765 breakpoint();
766 }
767 os::free(memblock);
768 }
769 return ptr;
770 #endif
771 }
772
773
774 void os::free(void *memblock) {
775 NOT_PRODUCT(inc_stat_counter(&num_frees, 1));
776 #ifdef ASSERT
777 if (memblock == NULL) return;
778 if ((intptr_t)memblock == (intptr_t)MallocCatchPtr) {
779 log_warning(malloc, free)("os::free caught " PTR_FORMAT, p2i(memblock));
780 breakpoint();
781 }
782 void* membase = MemTracker::record_free(memblock);
783 verify_memory(membase);
784
785 GuardedMemory guarded(membase);
786 size_t size = guarded.get_user_size();
787 inc_stat_counter(&free_bytes, size);
788 membase = guarded.release_for_freeing();
789 ::free(membase);
790 #else
791 void* membase = MemTracker::record_free(memblock);
792 ::free(membase);
793 #endif
794 }
795
796 void os::init_random(unsigned int initval) {
797 _rand_seed = initval;
798 }
799
800
801 static int random_helper(unsigned int rand_seed) {
802 /* standard, well-known linear congruential random generator with
803 * next_rand = (16807*seed) mod (2**31-1)
804 * see
805 * (1) "Random Number Generators: Good Ones Are Hard to Find",
806 * S.K. Park and K.W. Miller, Communications of the ACM 31:10 (Oct 1988),
807 * (2) "Two Fast Implementations of the 'Minimal Standard' Random
808 * Number Generator", David G. Carta, Comm. ACM 33, 1 (Jan 1990), pp. 87-88.
809 */
810 const unsigned int a = 16807;
811 const unsigned int m = 2147483647;
812 const int q = m / a; assert(q == 127773, "weird math");
813 const int r = m % a; assert(r == 2836, "weird math");
814
815 // compute az=2^31p+q
816 unsigned int lo = a * (rand_seed & 0xFFFF);
817 unsigned int hi = a * (rand_seed >> 16);
818 lo += (hi & 0x7FFF) << 16;
819
820 // if q overflowed, ignore the overflow and increment q
821 if (lo > m) {
822 lo &= m;
823 ++lo;
824 }
825 lo += hi >> 15;
826
827 // if (p+q) overflowed, ignore the overflow and increment (p+q)
828 if (lo > m) {
829 lo &= m;
830 ++lo;
831 }
832 return lo;
833 }
834
835 int os::random() {
836 // Make updating the random seed thread safe.
837 while (true) {
838 unsigned int seed = _rand_seed;
839 unsigned int rand = random_helper(seed);
840 if (Atomic::cmpxchg(rand, &_rand_seed, seed) == seed) {
841 return static_cast<int>(rand);
842 }
843 }
844 }
845
846 // The INITIALIZED state is distinguished from the SUSPENDED state because the
847 // conditions in which a thread is first started are different from those in which
848 // a suspension is resumed. These differences make it hard for us to apply the
849 // tougher checks when starting threads that we want to do when resuming them.
850 // However, when start_thread is called as a result of Thread.start, on a Java
851 // thread, the operation is synchronized on the Java Thread object. So there
852 // cannot be a race to start the thread and hence for the thread to exit while
853 // we are working on it. Non-Java threads that start Java threads either have
854 // to do so in a context in which races are impossible, or should do appropriate
855 // locking.
856
857 void os::start_thread(Thread* thread) {
858 // guard suspend/resume
859 MutexLockerEx ml(thread->SR_lock(), Mutex::_no_safepoint_check_flag);
860 OSThread* osthread = thread->osthread();
861 osthread->set_state(RUNNABLE);
862 pd_start_thread(thread);
863 }
864
865 void os::abort(bool dump_core) {
866 abort(dump_core && CreateCoredumpOnCrash, NULL, NULL);
867 }
868
869 //---------------------------------------------------------------------------
870 // Helper functions for fatal error handler
871
872 void os::print_hex_dump(outputStream* st, address start, address end, int unitsize) {
873 assert(unitsize == 1 || unitsize == 2 || unitsize == 4 || unitsize == 8, "just checking");
874
875 int cols = 0;
876 int cols_per_line = 0;
877 switch (unitsize) {
878 case 1: cols_per_line = 16; break;
879 case 2: cols_per_line = 8; break;
880 case 4: cols_per_line = 4; break;
881 case 8: cols_per_line = 2; break;
882 default: return;
883 }
884
885 address p = start;
886 st->print(PTR_FORMAT ": ", p2i(start));
887 while (p < end) {
888 switch (unitsize) {
889 case 1: st->print("%02x", *(u1*)p); break;
890 case 2: st->print("%04x", *(u2*)p); break;
891 case 4: st->print("%08x", *(u4*)p); break;
892 case 8: st->print("%016" FORMAT64_MODIFIER "x", *(u8*)p); break;
893 }
894 p += unitsize;
895 cols++;
896 if (cols >= cols_per_line && p < end) {
897 cols = 0;
898 st->cr();
899 st->print(PTR_FORMAT ": ", p2i(p));
900 } else {
901 st->print(" ");
902 }
903 }
904 st->cr();
905 }
906
907 void os::print_environment_variables(outputStream* st, const char** env_list) {
908 if (env_list) {
909 st->print_cr("Environment Variables:");
910
911 for (int i = 0; env_list[i] != NULL; i++) {
912 char *envvar = ::getenv(env_list[i]);
913 if (envvar != NULL) {
914 st->print("%s", env_list[i]);
915 st->print("=");
916 st->print_cr("%s", envvar);
917 }
918 }
919 }
920 }
921
922 void os::print_cpu_info(outputStream* st, char* buf, size_t buflen) {
923 // cpu
924 st->print("CPU:");
925 st->print("total %d", os::processor_count());
926 // It's not safe to query number of active processors after crash
927 // st->print("(active %d)", os::active_processor_count()); but we can
928 // print the initial number of active processors.
929 // We access the raw value here because the assert in the accessor will
930 // fail if the crash occurs before initialization of this value.
931 st->print(" (initial active %d)", _initial_active_processor_count);
932 st->print(" %s", VM_Version::features_string());
933 st->cr();
934 pd_print_cpu_info(st, buf, buflen);
935 }
936
937 // Print a one line string summarizing the cpu, number of cores, memory, and operating system version
938 void os::print_summary_info(outputStream* st, char* buf, size_t buflen) {
939 st->print("Host: ");
940 #ifndef PRODUCT
941 if (get_host_name(buf, buflen)) {
942 st->print("%s, ", buf);
943 }
944 #endif // PRODUCT
945 get_summary_cpu_info(buf, buflen);
946 st->print("%s, ", buf);
947 size_t mem = physical_memory()/G;
948 if (mem == 0) { // for low memory systems
949 mem = physical_memory()/M;
950 st->print("%d cores, " SIZE_FORMAT "M, ", processor_count(), mem);
951 } else {
952 st->print("%d cores, " SIZE_FORMAT "G, ", processor_count(), mem);
953 }
954 get_summary_os_info(buf, buflen);
955 st->print_raw(buf);
956 st->cr();
957 }
958
959 void os::print_date_and_time(outputStream *st, char* buf, size_t buflen) {
960 const int secs_per_day = 86400;
961 const int secs_per_hour = 3600;
962 const int secs_per_min = 60;
963
964 time_t tloc;
965 (void)time(&tloc);
966 char* timestring = ctime(&tloc); // ctime adds newline.
967 // edit out the newline
968 char* nl = strchr(timestring, '\n');
969 if (nl != NULL) {
970 *nl = '\0';
971 }
972
973 struct tm tz;
974 if (localtime_pd(&tloc, &tz) != NULL) {
975 ::strftime(buf, buflen, "%Z", &tz);
976 st->print("Time: %s %s", timestring, buf);
977 } else {
978 st->print("Time: %s", timestring);
979 }
980
981 double t = os::elapsedTime();
982 // NOTE: It tends to crash after a SEGV if we want to printf("%f",...) in
983 // Linux. Must be a bug in glibc ? Workaround is to round "t" to int
984 // before printf. We lost some precision, but who cares?
985 int eltime = (int)t; // elapsed time in seconds
986
987 // print elapsed time in a human-readable format:
988 int eldays = eltime / secs_per_day;
989 int day_secs = eldays * secs_per_day;
990 int elhours = (eltime - day_secs) / secs_per_hour;
991 int hour_secs = elhours * secs_per_hour;
992 int elmins = (eltime - day_secs - hour_secs) / secs_per_min;
993 int minute_secs = elmins * secs_per_min;
994 int elsecs = (eltime - day_secs - hour_secs - minute_secs);
995 st->print_cr(" elapsed time: %d seconds (%dd %dh %dm %ds)", eltime, eldays, elhours, elmins, elsecs);
996 }
997
998
999 // Check if pointer can be read from (4-byte read access).
1000 // Helps to prove validity of a not-NULL pointer.
1001 // Returns true in very early stages of VM life when stub is not yet generated.
1002 #define SAFEFETCH_DEFAULT true
1003 bool os::is_readable_pointer(const void* p) {
1004 if (!CanUseSafeFetch32()) {
1005 return SAFEFETCH_DEFAULT;
1006 }
1007 int* const aligned = (int*) align_down((intptr_t)p, 4);
1008 int cafebabe = 0xcafebabe; // tester value 1
1009 int deadbeef = 0xdeadbeef; // tester value 2
1010 return (SafeFetch32(aligned, cafebabe) != cafebabe) || (SafeFetch32(aligned, deadbeef) != deadbeef);
1011 }
1012
1013 bool os::is_readable_range(const void* from, const void* to) {
1014 for (address p = align_down((address)from, min_page_size()); p < to; p += min_page_size()) {
1015 if (!is_readable_pointer(p)) {
1016 return false;
1017 }
1018 }
1019 return true;
1020 }
1021
1022
1023 // moved from debug.cpp (used to be find()) but still called from there
1024 // The verbose parameter is only set by the debug code in one case
1025 void os::print_location(outputStream* st, intptr_t x, bool verbose) {
1026 address addr = (address)x;
1027 // Handle NULL first, so later checks don't need to protect against it.
1028 if (addr == NULL) {
1029 st->print_cr("0x0 is NULL");
1030 return;
1031 }
1032
1033 // Check if addr points into a code blob.
1034 CodeBlob* b = CodeCache::find_blob_unsafe(addr);
1035 if (b != NULL) {
1036 b->dump_for_addr(addr, st, verbose);
1037 return;
1038 }
1039
1040 // Check if addr points into Java heap.
1041 if (Universe::heap()->is_in(addr)) {
1042 oop o = oopDesc::oop_or_null(addr);
1043 if (o != NULL) {
1044 if ((HeapWord*)o == (HeapWord*)addr) {
1045 st->print(INTPTR_FORMAT " is an oop: ", p2i(addr));
1046 } else {
1047 st->print(INTPTR_FORMAT " is pointing into object: " , p2i(addr));
1048 }
1049 o->print_on(st);
1050 return;
1051 }
1052 } else if (Universe::heap()->is_in_reserved(addr)) {
1053 st->print_cr(INTPTR_FORMAT " is an unallocated location in the heap", p2i(addr));
1054 return;
1055 }
1056
1057 // Compressed oop needs to be decoded first.
1058 #ifdef _LP64
1059 if (UseCompressedOops && ((uintptr_t)addr &~ (uintptr_t)max_juint) == 0) {
1060 narrowOop narrow_oop = (narrowOop)(uintptr_t)addr;
1061 oop o = oopDesc::decode_oop_raw(narrow_oop);
1062
1063 if (oopDesc::is_valid(o)) {
1064 st->print(UINT32_FORMAT " is a compressed pointer to object: ", narrow_oop);
1065 o->print_on(st);
1066 return;
1067 }
1068 }
1069 #endif
1070
1071 bool accessible = is_readable_pointer(addr);
1072
1073 // Check if addr is a JNI handle.
1074 if (align_down((intptr_t)addr, sizeof(intptr_t)) != 0 && accessible) {
1075 if (JNIHandles::is_global_handle((jobject) addr)) {
1076 st->print_cr(INTPTR_FORMAT " is a global jni handle", p2i(addr));
1077 return;
1078 }
1079 if (JNIHandles::is_weak_global_handle((jobject) addr)) {
1080 st->print_cr(INTPTR_FORMAT " is a weak global jni handle", p2i(addr));
1081 return;
1082 }
1083 #ifndef PRODUCT
1084 // we don't keep the block list in product mode
1085 if (JNIHandles::is_local_handle((jobject) addr)) {
1086 st->print_cr(INTPTR_FORMAT " is a local jni handle", p2i(addr));
1087 return;
1088 }
1089 #endif
1090 }
1091
1092 // Check if addr belongs to a Java thread.
1093 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next(); ) {
1094 // Check for privilege stack
1095 if (thread->privileged_stack_top() != NULL &&
1096 thread->privileged_stack_top()->contains(addr)) {
1097 st->print_cr(INTPTR_FORMAT " is pointing into the privilege stack "
1098 "for thread: " INTPTR_FORMAT, p2i(addr), p2i(thread));
1099 if (verbose) thread->print_on(st);
1100 return;
1101 }
1102 // If the addr is a java thread print information about that.
1103 if (addr == (address)thread) {
1104 if (verbose) {
1105 thread->print_on(st);
1106 } else {
1107 st->print_cr(INTPTR_FORMAT " is a thread", p2i(addr));
1108 }
1109 return;
1110 }
1111 // If the addr is in the stack region for this thread then report that
1112 // and print thread info
1113 if (thread->on_local_stack(addr)) {
1114 st->print_cr(INTPTR_FORMAT " is pointing into the stack for thread: "
1115 INTPTR_FORMAT, p2i(addr), p2i(thread));
1116 if (verbose) thread->print_on(st);
1117 return;
1118 }
1119 }
1120
1121 // Check if in metaspace and print types that have vptrs
1122 if (Metaspace::contains(addr)) {
1123 if (Klass::is_valid((Klass*)addr)) {
1124 st->print_cr(INTPTR_FORMAT " is a pointer to class: ", p2i(addr));
1125 ((Klass*)addr)->print_on(st);
1126 } else if (Method::is_valid_method((const Method*)addr)) {
1127 ((Method*)addr)->print_value_on(st);
1128 st->cr();
1129 } else {
1130 // Use addr->print() from the debugger instead (not here)
1131 st->print_cr(INTPTR_FORMAT " is pointing into metadata", p2i(addr));
1132 }
1133 return;
1134 }
1135
1136 // Compressed klass needs to be decoded first.
1137 #ifdef _LP64
1138 if (UseCompressedClassPointers && ((uintptr_t)addr &~ (uintptr_t)max_juint) == 0) {
1139 narrowKlass narrow_klass = (narrowKlass)(uintptr_t)addr;
1140 Klass* k = Klass::decode_klass_raw(narrow_klass);
1141
1142 if (Klass::is_valid(k)) {
1143 st->print_cr(UINT32_FORMAT " is a compressed pointer to class: " INTPTR_FORMAT, narrow_klass, p2i((HeapWord*)k));
1144 k->print_on(st);
1145 return;
1146 }
1147 }
1148 #endif
1149
1150 // Try an OS specific find
1151 if (os::find(addr, st)) {
1152 return;
1153 }
1154
1155 if (accessible) {
1156 st->print(INTPTR_FORMAT " points into unknown readable memory:", p2i(addr));
1157 for (address p = addr; p < align_up(addr + 1, sizeof(intptr_t)); ++p) {
1158 st->print(" %02x", *(u1*)p);
1159 }
1160 st->cr();
1161 return;
1162 }
1163
1164 st->print_cr(INTPTR_FORMAT " is an unknown value", p2i(addr));
1165 }
1166
1167 // Looks like all platforms can use the same function to check if C
1168 // stack is walkable beyond current frame. The check for fp() is not
1169 // necessary on Sparc, but it's harmless.
1170 bool os::is_first_C_frame(frame* fr) {
1171 // Load up sp, fp, sender sp and sender fp, check for reasonable values.
1172 // Check usp first, because if that's bad the other accessors may fault
1173 // on some architectures. Ditto ufp second, etc.
1174 uintptr_t fp_align_mask = (uintptr_t)(sizeof(address)-1);
1175 // sp on amd can be 32 bit aligned.
1176 uintptr_t sp_align_mask = (uintptr_t)(sizeof(int)-1);
1177
1178 uintptr_t usp = (uintptr_t)fr->sp();
1179 if ((usp & sp_align_mask) != 0) return true;
1180
1181 uintptr_t ufp = (uintptr_t)fr->fp();
1182 if ((ufp & fp_align_mask) != 0) return true;
1183
1184 uintptr_t old_sp = (uintptr_t)fr->sender_sp();
1185 if ((old_sp & sp_align_mask) != 0) return true;
1186 if (old_sp == 0 || old_sp == (uintptr_t)-1) return true;
1187
1188 uintptr_t old_fp = (uintptr_t)fr->link();
1189 if ((old_fp & fp_align_mask) != 0) return true;
1190 if (old_fp == 0 || old_fp == (uintptr_t)-1 || old_fp == ufp) return true;
1191
1192 // stack grows downwards; if old_fp is below current fp or if the stack
1193 // frame is too large, either the stack is corrupted or fp is not saved
1194 // on stack (i.e. on x86, ebp may be used as general register). The stack
1195 // is not walkable beyond current frame.
1196 if (old_fp < ufp) return true;
1197 if (old_fp - ufp > 64 * K) return true;
1198
1199 return false;
1200 }
1201
1202
1203 // Set up the boot classpath.
1204
1205 char* os::format_boot_path(const char* format_string,
1206 const char* home,
1207 int home_len,
1208 char fileSep,
1209 char pathSep) {
1210 assert((fileSep == '/' && pathSep == ':') ||
1211 (fileSep == '\\' && pathSep == ';'), "unexpected separator chars");
1212
1213 // Scan the format string to determine the length of the actual
1214 // boot classpath, and handle platform dependencies as well.
1215 int formatted_path_len = 0;
1216 const char* p;
1217 for (p = format_string; *p != 0; ++p) {
1218 if (*p == '%') formatted_path_len += home_len - 1;
1219 ++formatted_path_len;
1220 }
1221
1222 char* formatted_path = NEW_C_HEAP_ARRAY(char, formatted_path_len + 1, mtInternal);
1223 if (formatted_path == NULL) {
1224 return NULL;
1225 }
1226
1227 // Create boot classpath from format, substituting separator chars and
1228 // java home directory.
1229 char* q = formatted_path;
1230 for (p = format_string; *p != 0; ++p) {
1231 switch (*p) {
1232 case '%':
1233 strcpy(q, home);
1234 q += home_len;
1235 break;
1236 case '/':
1237 *q++ = fileSep;
1238 break;
1239 case ':':
1240 *q++ = pathSep;
1241 break;
1242 default:
1243 *q++ = *p;
1244 }
1245 }
1246 *q = '\0';
1247
1248 assert((q - formatted_path) == formatted_path_len, "formatted_path size botched");
1249 return formatted_path;
1250 }
1251
1252 // This function is a proxy to fopen, it tries to add a non standard flag ('e' or 'N')
1253 // that ensures automatic closing of the file on exec. If it can not find support in
1254 // the underlying c library, it will make an extra system call (fcntl) to ensure automatic
1255 // closing of the file on exec.
1256 FILE* os::fopen(const char* path, const char* mode) {
1257 char modified_mode[20];
1258 assert(strlen(mode) + 1 < sizeof(modified_mode), "mode chars plus one extra must fit in buffer");
1259 sprintf(modified_mode, "%s" LINUX_ONLY("e") BSD_ONLY("e") WINDOWS_ONLY("N"), mode);
1260 FILE* file = ::fopen(path, modified_mode);
1261
1262 #if !(defined LINUX || defined BSD || defined _WINDOWS)
1263 // assume fcntl FD_CLOEXEC support as a backup solution when 'e' or 'N'
1264 // is not supported as mode in fopen
1265 if (file != NULL) {
1266 int fd = fileno(file);
1267 if (fd != -1) {
1268 int fd_flags = fcntl(fd, F_GETFD);
1269 if (fd_flags != -1) {
1270 fcntl(fd, F_SETFD, fd_flags | FD_CLOEXEC);
1271 }
1272 }
1273 }
1274 #endif
1275
1276 return file;
1277 }
1278
1279 bool os::set_boot_path(char fileSep, char pathSep) {
1280 const char* home = Arguments::get_java_home();
1281 int home_len = (int)strlen(home);
1282
1283 struct stat st;
1284
1285 // modular image if "modules" jimage exists
1286 char* jimage = format_boot_path("%/lib/" MODULES_IMAGE_NAME, home, home_len, fileSep, pathSep);
1287 if (jimage == NULL) return false;
1288 bool has_jimage = (os::stat(jimage, &st) == 0);
1289 if (has_jimage) {
1290 Arguments::set_sysclasspath(jimage, true);
1291 FREE_C_HEAP_ARRAY(char, jimage);
1292 return true;
1293 }
1294 FREE_C_HEAP_ARRAY(char, jimage);
1295
1296 // check if developer build with exploded modules
1297 char* base_classes = format_boot_path("%/modules/" JAVA_BASE_NAME, home, home_len, fileSep, pathSep);
1298 if (base_classes == NULL) return false;
1299 if (os::stat(base_classes, &st) == 0) {
1300 Arguments::set_sysclasspath(base_classes, false);
1301 FREE_C_HEAP_ARRAY(char, base_classes);
1302 return true;
1303 }
1304 FREE_C_HEAP_ARRAY(char, base_classes);
1305
1306 return false;
1307 }
1308
1309 /*
1310 * Splits a path, based on its separator, the number of
1311 * elements is returned back in n.
1312 * It is the callers responsibility to:
1313 * a> check the value of n, and n may be 0.
1314 * b> ignore any empty path elements
1315 * c> free up the data.
1316 */
1317 char** os::split_path(const char* path, int* n) {
1318 *n = 0;
1319 if (path == NULL || strlen(path) == 0) {
1320 return NULL;
1321 }
1322 const char psepchar = *os::path_separator();
1323 char* inpath = (char*)NEW_C_HEAP_ARRAY(char, strlen(path) + 1, mtInternal);
1324 if (inpath == NULL) {
1325 return NULL;
1326 }
1327 strcpy(inpath, path);
1328 int count = 1;
1329 char* p = strchr(inpath, psepchar);
1330 // Get a count of elements to allocate memory
1331 while (p != NULL) {
1332 count++;
1333 p++;
1334 p = strchr(p, psepchar);
1335 }
1336 char** opath = (char**) NEW_C_HEAP_ARRAY(char*, count, mtInternal);
1337 if (opath == NULL) {
1338 return NULL;
1339 }
1340
1341 // do the actual splitting
1342 p = inpath;
1343 for (int i = 0 ; i < count ; i++) {
1344 size_t len = strcspn(p, os::path_separator());
1345 if (len > JVM_MAXPATHLEN) {
1346 return NULL;
1347 }
1348 // allocate the string and add terminator storage
1349 char* s = (char*)NEW_C_HEAP_ARRAY(char, len + 1, mtInternal);
1350 if (s == NULL) {
1351 return NULL;
1352 }
1353 strncpy(s, p, len);
1354 s[len] = '\0';
1355 opath[i] = s;
1356 p += len + 1;
1357 }
1358 FREE_C_HEAP_ARRAY(char, inpath);
1359 *n = count;
1360 return opath;
1361 }
1362
1363 void os::set_memory_serialize_page(address page) {
1364 int count = log2_intptr(sizeof(class JavaThread)) - log2_intptr(64);
1365 _mem_serialize_page = (volatile int32_t *)page;
1366 // We initialize the serialization page shift count here
1367 // We assume a cache line size of 64 bytes
1368 assert(SerializePageShiftCount == count, "JavaThread size changed; "
1369 "SerializePageShiftCount constant should be %d", count);
1370 set_serialize_page_mask((uintptr_t)(vm_page_size() - sizeof(int32_t)));
1371 }
1372
1373 static volatile intptr_t SerializePageLock = 0;
1374
1375 // This method is called from signal handler when SIGSEGV occurs while the current
1376 // thread tries to store to the "read-only" memory serialize page during state
1377 // transition.
1378 void os::block_on_serialize_page_trap() {
1379 log_debug(safepoint)("Block until the serialize page permission restored");
1380
1381 // When VMThread is holding the SerializePageLock during modifying the
1382 // access permission of the memory serialize page, the following call
1383 // will block until the permission of that page is restored to rw.
1384 // Generally, it is unsafe to manipulate locks in signal handlers, but in
1385 // this case, it's OK as the signal is synchronous and we know precisely when
1386 // it can occur.
1387 Thread::muxAcquire(&SerializePageLock, "set_memory_serialize_page");
1388 Thread::muxRelease(&SerializePageLock);
1389 }
1390
1391 // Serialize all thread state variables
1392 void os::serialize_thread_states() {
1393 // On some platforms such as Solaris & Linux, the time duration of the page
1394 // permission restoration is observed to be much longer than expected due to
1395 // scheduler starvation problem etc. To avoid the long synchronization
1396 // time and expensive page trap spinning, 'SerializePageLock' is used to block
1397 // the mutator thread if such case is encountered. See bug 6546278 for details.
1398 Thread::muxAcquire(&SerializePageLock, "serialize_thread_states");
1399 os::protect_memory((char *)os::get_memory_serialize_page(),
1400 os::vm_page_size(), MEM_PROT_READ);
1401 os::protect_memory((char *)os::get_memory_serialize_page(),
1402 os::vm_page_size(), MEM_PROT_RW);
1403 Thread::muxRelease(&SerializePageLock);
1404 }
1405
1406 // Returns true if the current stack pointer is above the stack shadow
1407 // pages, false otherwise.
1408 bool os::stack_shadow_pages_available(Thread *thread, const methodHandle& method, address sp) {
1409 if (!thread->is_Java_thread()) return false;
1410 // Check if we have StackShadowPages above the yellow zone. This parameter
1411 // is dependent on the depth of the maximum VM call stack possible from
1412 // the handler for stack overflow. 'instanceof' in the stack overflow
1413 // handler or a println uses at least 8k stack of VM and native code
1414 // respectively.
1415 const int framesize_in_bytes =
1416 Interpreter::size_top_interpreter_activation(method()) * wordSize;
1417
1418 address limit = ((JavaThread*)thread)->stack_end() +
1419 (JavaThread::stack_guard_zone_size() + JavaThread::stack_shadow_zone_size());
1420
1421 return sp > (limit + framesize_in_bytes);
1422 }
1423
1424 size_t os::page_size_for_region(size_t region_size, size_t min_pages, bool must_be_aligned) {
1425 assert(min_pages > 0, "sanity");
1426 if (UseLargePages) {
1427 const size_t max_page_size = region_size / min_pages;
1428
1429 for (size_t i = 0; _page_sizes[i] != 0; ++i) {
1430 const size_t page_size = _page_sizes[i];
1431 if (page_size <= max_page_size) {
1432 if (!must_be_aligned || is_aligned(region_size, page_size)) {
1433 return page_size;
1434 }
1435 }
1436 }
1437 }
1438
1439 return vm_page_size();
1440 }
1441
1442 size_t os::page_size_for_region_aligned(size_t region_size, size_t min_pages) {
1443 return page_size_for_region(region_size, min_pages, true);
1444 }
1445
1446 size_t os::page_size_for_region_unaligned(size_t region_size, size_t min_pages) {
1447 return page_size_for_region(region_size, min_pages, false);
1448 }
1449
1450 static const char* errno_to_string (int e, bool short_text) {
1451 #define ALL_SHARED_ENUMS(X) \
1452 X(E2BIG, "Argument list too long") \
1453 X(EACCES, "Permission denied") \
1454 X(EADDRINUSE, "Address in use") \
1455 X(EADDRNOTAVAIL, "Address not available") \
1456 X(EAFNOSUPPORT, "Address family not supported") \
1457 X(EAGAIN, "Resource unavailable, try again") \
1458 X(EALREADY, "Connection already in progress") \
1459 X(EBADF, "Bad file descriptor") \
1460 X(EBADMSG, "Bad message") \
1461 X(EBUSY, "Device or resource busy") \
1462 X(ECANCELED, "Operation canceled") \
1463 X(ECHILD, "No child processes") \
1464 X(ECONNABORTED, "Connection aborted") \
1465 X(ECONNREFUSED, "Connection refused") \
1466 X(ECONNRESET, "Connection reset") \
1467 X(EDEADLK, "Resource deadlock would occur") \
1468 X(EDESTADDRREQ, "Destination address required") \
1469 X(EDOM, "Mathematics argument out of domain of function") \
1470 X(EEXIST, "File exists") \
1471 X(EFAULT, "Bad address") \
1472 X(EFBIG, "File too large") \
1473 X(EHOSTUNREACH, "Host is unreachable") \
1474 X(EIDRM, "Identifier removed") \
1475 X(EILSEQ, "Illegal byte sequence") \
1476 X(EINPROGRESS, "Operation in progress") \
1477 X(EINTR, "Interrupted function") \
1478 X(EINVAL, "Invalid argument") \
1479 X(EIO, "I/O error") \
1480 X(EISCONN, "Socket is connected") \
1481 X(EISDIR, "Is a directory") \
1482 X(ELOOP, "Too many levels of symbolic links") \
1483 X(EMFILE, "Too many open files") \
1484 X(EMLINK, "Too many links") \
1485 X(EMSGSIZE, "Message too large") \
1486 X(ENAMETOOLONG, "Filename too long") \
1487 X(ENETDOWN, "Network is down") \
1488 X(ENETRESET, "Connection aborted by network") \
1489 X(ENETUNREACH, "Network unreachable") \
1490 X(ENFILE, "Too many files open in system") \
1491 X(ENOBUFS, "No buffer space available") \
1492 X(ENODATA, "No message is available on the STREAM head read queue") \
1493 X(ENODEV, "No such device") \
1494 X(ENOENT, "No such file or directory") \
1495 X(ENOEXEC, "Executable file format error") \
1496 X(ENOLCK, "No locks available") \
1497 X(ENOLINK, "Reserved") \
1498 X(ENOMEM, "Not enough space") \
1499 X(ENOMSG, "No message of the desired type") \
1500 X(ENOPROTOOPT, "Protocol not available") \
1501 X(ENOSPC, "No space left on device") \
1502 X(ENOSR, "No STREAM resources") \
1503 X(ENOSTR, "Not a STREAM") \
1504 X(ENOSYS, "Function not supported") \
1505 X(ENOTCONN, "The socket is not connected") \
1506 X(ENOTDIR, "Not a directory") \
1507 X(ENOTEMPTY, "Directory not empty") \
1508 X(ENOTSOCK, "Not a socket") \
1509 X(ENOTSUP, "Not supported") \
1510 X(ENOTTY, "Inappropriate I/O control operation") \
1511 X(ENXIO, "No such device or address") \
1512 X(EOPNOTSUPP, "Operation not supported on socket") \
1513 X(EOVERFLOW, "Value too large to be stored in data type") \
1514 X(EPERM, "Operation not permitted") \
1515 X(EPIPE, "Broken pipe") \
1516 X(EPROTO, "Protocol error") \
1517 X(EPROTONOSUPPORT, "Protocol not supported") \
1518 X(EPROTOTYPE, "Protocol wrong type for socket") \
1519 X(ERANGE, "Result too large") \
1520 X(EROFS, "Read-only file system") \
1521 X(ESPIPE, "Invalid seek") \
1522 X(ESRCH, "No such process") \
1523 X(ETIME, "Stream ioctl() timeout") \
1524 X(ETIMEDOUT, "Connection timed out") \
1525 X(ETXTBSY, "Text file busy") \
1526 X(EWOULDBLOCK, "Operation would block") \
1527 X(EXDEV, "Cross-device link")
1528
1529 #define DEFINE_ENTRY(e, text) { e, #e, text },
1530
1531 static const struct {
1532 int v;
1533 const char* short_text;
1534 const char* long_text;
1535 } table [] = {
1536
1537 ALL_SHARED_ENUMS(DEFINE_ENTRY)
1538
1539 // The following enums are not defined on all platforms.
1540 #ifdef ESTALE
1541 DEFINE_ENTRY(ESTALE, "Reserved")
1542 #endif
1543 #ifdef EDQUOT
1544 DEFINE_ENTRY(EDQUOT, "Reserved")
1545 #endif
1546 #ifdef EMULTIHOP
1547 DEFINE_ENTRY(EMULTIHOP, "Reserved")
1548 #endif
1549
1550 // End marker.
1551 { -1, "Unknown errno", "Unknown error" }
1552
1553 };
1554
1555 #undef DEFINE_ENTRY
1556 #undef ALL_FLAGS
1557
1558 int i = 0;
1559 while (table[i].v != -1 && table[i].v != e) {
1560 i ++;
1561 }
1562
1563 return short_text ? table[i].short_text : table[i].long_text;
1564
1565 }
1566
1567 const char* os::strerror(int e) {
1568 return errno_to_string(e, false);
1569 }
1570
1571 const char* os::errno_name(int e) {
1572 return errno_to_string(e, true);
1573 }
1574
1575 void os::trace_page_sizes(const char* str, const size_t* page_sizes, int count) {
1576 LogTarget(Info, pagesize) log;
1577 if (log.is_enabled()) {
1578 LogStream out(log);
1579
1580 out.print("%s: ", str);
1581 for (int i = 0; i < count; ++i) {
1582 out.print(" " SIZE_FORMAT, page_sizes[i]);
1583 }
1584 out.cr();
1585 }
1586 }
1587
1588 #define trace_page_size_params(size) byte_size_in_exact_unit(size), exact_unit_for_byte_size(size)
1589
1590 void os::trace_page_sizes(const char* str,
1591 const size_t region_min_size,
1592 const size_t region_max_size,
1593 const size_t page_size,
1594 const char* base,
1595 const size_t size) {
1596
1597 log_info(pagesize)("%s: "
1598 " min=" SIZE_FORMAT "%s"
1599 " max=" SIZE_FORMAT "%s"
1600 " base=" PTR_FORMAT
1601 " page_size=" SIZE_FORMAT "%s"
1602 " size=" SIZE_FORMAT "%s",
1603 str,
1604 trace_page_size_params(region_min_size),
1605 trace_page_size_params(region_max_size),
1606 p2i(base),
1607 trace_page_size_params(page_size),
1608 trace_page_size_params(size));
1609 }
1610
1611 void os::trace_page_sizes_for_requested_size(const char* str,
1612 const size_t requested_size,
1613 const size_t page_size,
1614 const size_t alignment,
1615 const char* base,
1616 const size_t size) {
1617
1618 log_info(pagesize)("%s:"
1619 " req_size=" SIZE_FORMAT "%s"
1620 " base=" PTR_FORMAT
1621 " page_size=" SIZE_FORMAT "%s"
1622 " alignment=" SIZE_FORMAT "%s"
1623 " size=" SIZE_FORMAT "%s",
1624 str,
1625 trace_page_size_params(requested_size),
1626 p2i(base),
1627 trace_page_size_params(page_size),
1628 trace_page_size_params(alignment),
1629 trace_page_size_params(size));
1630 }
1631
1632
1633 // This is the working definition of a server class machine:
1634 // >= 2 physical CPU's and >=2GB of memory, with some fuzz
1635 // because the graphics memory (?) sometimes masks physical memory.
1636 // If you want to change the definition of a server class machine
1637 // on some OS or platform, e.g., >=4GB on Windows platforms,
1638 // then you'll have to parameterize this method based on that state,
1639 // as was done for logical processors here, or replicate and
1640 // specialize this method for each platform. (Or fix os to have
1641 // some inheritance structure and use subclassing. Sigh.)
1642 // If you want some platform to always or never behave as a server
1643 // class machine, change the setting of AlwaysActAsServerClassMachine
1644 // and NeverActAsServerClassMachine in globals*.hpp.
1645 bool os::is_server_class_machine() {
1646 // First check for the early returns
1647 if (NeverActAsServerClassMachine) {
1648 return false;
1649 }
1650 if (AlwaysActAsServerClassMachine) {
1651 return true;
1652 }
1653 // Then actually look at the machine
1654 bool result = false;
1655 const unsigned int server_processors = 2;
1656 const julong server_memory = 2UL * G;
1657 // We seem not to get our full complement of memory.
1658 // We allow some part (1/8?) of the memory to be "missing",
1659 // based on the sizes of DIMMs, and maybe graphics cards.
1660 const julong missing_memory = 256UL * M;
1661
1662 /* Is this a server class machine? */
1663 if ((os::active_processor_count() >= (int)server_processors) &&
1664 (os::physical_memory() >= (server_memory - missing_memory))) {
1665 const unsigned int logical_processors =
1666 VM_Version::logical_processors_per_package();
1667 if (logical_processors > 1) {
1668 const unsigned int physical_packages =
1669 os::active_processor_count() / logical_processors;
1670 if (physical_packages >= server_processors) {
1671 result = true;
1672 }
1673 } else {
1674 result = true;
1675 }
1676 }
1677 return result;
1678 }
1679
1680 void os::initialize_initial_active_processor_count() {
1681 assert(_initial_active_processor_count == 0, "Initial active processor count already set.");
1682 _initial_active_processor_count = active_processor_count();
1683 log_debug(os)("Initial active processor count set to %d" , _initial_active_processor_count);
1684 }
1685
1686 void os::SuspendedThreadTask::run() {
1687 internal_do_task();
1688 _done = true;
1689 }
1690
1691 bool os::create_stack_guard_pages(char* addr, size_t bytes) {
1692 return os::pd_create_stack_guard_pages(addr, bytes);
1693 }
1694
1695 char* os::reserve_memory(size_t bytes, char* addr, size_t alignment_hint, int file_desc) {
1696 char* result = NULL;
1697
1698 if (file_desc != -1) {
1699 // Could have called pd_reserve_memory() followed by replace_existing_mapping_with_file_mapping(),
1700 // but AIX may use SHM in which case its more trouble to detach the segment and remap memory to the file.
1701 result = os::map_memory_to_file(addr, bytes, file_desc);
1702 if (result != NULL) {
1703 MemTracker::record_virtual_memory_reserve_and_commit((address)result, bytes, CALLER_PC);
1704 }
1705 } else {
1706 result = pd_reserve_memory(bytes, addr, alignment_hint);
1707 if (result != NULL) {
1708 MemTracker::record_virtual_memory_reserve((address)result, bytes, CALLER_PC);
1709 }
1710 }
1711
1712 return result;
1713 }
1714
1715 char* os::reserve_memory(size_t bytes, char* addr, size_t alignment_hint,
1716 MEMFLAGS flags) {
1717 char* result = pd_reserve_memory(bytes, addr, alignment_hint);
1718 if (result != NULL) {
1719 MemTracker::record_virtual_memory_reserve((address)result, bytes, CALLER_PC);
1720 MemTracker::record_virtual_memory_type((address)result, flags);
1721 }
1722
1723 return result;
1724 }
1725
1726 char* os::attempt_reserve_memory_at(size_t bytes, char* addr, int file_desc) {
1727 char* result = NULL;
1728 if (file_desc != -1) {
1729 result = pd_attempt_reserve_memory_at(bytes, addr, file_desc);
1730 if (result != NULL) {
1731 MemTracker::record_virtual_memory_reserve_and_commit((address)result, bytes, CALLER_PC);
1732 }
1733 } else {
1734 result = pd_attempt_reserve_memory_at(bytes, addr);
1735 if (result != NULL) {
1736 MemTracker::record_virtual_memory_reserve((address)result, bytes, CALLER_PC);
1737 }
1738 }
1739 return result;
1740 }
1741
1742 void os::split_reserved_memory(char *base, size_t size,
1743 size_t split, bool realloc) {
1744 pd_split_reserved_memory(base, size, split, realloc);
1745 }
1746
1747 bool os::commit_memory(char* addr, size_t bytes, bool executable) {
1748 bool res = pd_commit_memory(addr, bytes, executable);
1749 if (res) {
1750 MemTracker::record_virtual_memory_commit((address)addr, bytes, CALLER_PC);
1751 }
1752 return res;
1753 }
1754
1755 bool os::commit_memory(char* addr, size_t size, size_t alignment_hint,
1756 bool executable) {
1757 bool res = os::pd_commit_memory(addr, size, alignment_hint, executable);
1758 if (res) {
1759 MemTracker::record_virtual_memory_commit((address)addr, size, CALLER_PC);
1760 }
1761 return res;
1762 }
1763
1764 void os::commit_memory_or_exit(char* addr, size_t bytes, bool executable,
1765 const char* mesg) {
1766 pd_commit_memory_or_exit(addr, bytes, executable, mesg);
1767 MemTracker::record_virtual_memory_commit((address)addr, bytes, CALLER_PC);
1768 }
1769
1770 void os::commit_memory_or_exit(char* addr, size_t size, size_t alignment_hint,
1771 bool executable, const char* mesg) {
1772 os::pd_commit_memory_or_exit(addr, size, alignment_hint, executable, mesg);
1773 MemTracker::record_virtual_memory_commit((address)addr, size, CALLER_PC);
1774 }
1775
1776 bool os::uncommit_memory(char* addr, size_t bytes) {
1777 bool res;
1778 if (MemTracker::tracking_level() > NMT_minimal) {
1779 Tracker tkr(Tracker::uncommit);
1780 res = pd_uncommit_memory(addr, bytes);
1781 if (res) {
1782 tkr.record((address)addr, bytes);
1783 }
1784 } else {
1785 res = pd_uncommit_memory(addr, bytes);
1786 }
1787 return res;
1788 }
1789
1790 bool os::release_memory(char* addr, size_t bytes) {
1791 bool res;
1792 if (MemTracker::tracking_level() > NMT_minimal) {
1793 Tracker tkr(Tracker::release);
1794 res = pd_release_memory(addr, bytes);
1795 if (res) {
1796 tkr.record((address)addr, bytes);
1797 }
1798 } else {
1799 res = pd_release_memory(addr, bytes);
1800 }
1801 return res;
1802 }
1803
1804 void os::pretouch_memory(void* start, void* end, size_t page_size) {
1805 for (volatile char *p = (char*)start; p < (char*)end; p += page_size) {
1806 *p = 0;
1807 }
1808 }
1809
1810 char* os::map_memory(int fd, const char* file_name, size_t file_offset,
1811 char *addr, size_t bytes, bool read_only,
1812 bool allow_exec) {
1813 char* result = pd_map_memory(fd, file_name, file_offset, addr, bytes, read_only, allow_exec);
1814 if (result != NULL) {
1815 MemTracker::record_virtual_memory_reserve_and_commit((address)result, bytes, CALLER_PC);
1816 }
1817 return result;
1818 }
1819
1820 char* os::remap_memory(int fd, const char* file_name, size_t file_offset,
1821 char *addr, size_t bytes, bool read_only,
1822 bool allow_exec) {
1823 return pd_remap_memory(fd, file_name, file_offset, addr, bytes,
1824 read_only, allow_exec);
1825 }
1826
1827 bool os::unmap_memory(char *addr, size_t bytes) {
1828 bool result;
1829 if (MemTracker::tracking_level() > NMT_minimal) {
1830 Tracker tkr(Tracker::release);
1831 result = pd_unmap_memory(addr, bytes);
1832 if (result) {
1833 tkr.record((address)addr, bytes);
1834 }
1835 } else {
1836 result = pd_unmap_memory(addr, bytes);
1837 }
1838 return result;
1839 }
1840
1841 void os::free_memory(char *addr, size_t bytes, size_t alignment_hint) {
1842 pd_free_memory(addr, bytes, alignment_hint);
1843 }
1844
1845 void os::realign_memory(char *addr, size_t bytes, size_t alignment_hint) {
1846 pd_realign_memory(addr, bytes, alignment_hint);
1847 }
1848
1849 #ifndef _WINDOWS
1850 /* try to switch state from state "from" to state "to"
1851 * returns the state set after the method is complete
1852 */
1853 os::SuspendResume::State os::SuspendResume::switch_state(os::SuspendResume::State from,
1854 os::SuspendResume::State to)
1855 {
1856 os::SuspendResume::State result = Atomic::cmpxchg(to, &_state, from);
1857 if (result == from) {
1858 // success
1859 return to;
1860 }
1861 return result;
1862 }
1863 #endif