1 /*
2 * Copyright (c) 1997, 2025, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2021, Azul Systems, Inc. All rights reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 *
24 */
25
26 #include "cds/cdsConfig.hpp"
27 #include "classfile/javaClasses.hpp"
28 #include "classfile/javaThreadStatus.hpp"
29 #include "gc/shared/barrierSet.hpp"
30 #include "jfr/jfrEvents.hpp"
31 #include "jvm.h"
32 #include "jvmtifiles/jvmtiEnv.hpp"
33 #include "logging/log.hpp"
34 #include "memory/allocation.inline.hpp"
35 #include "memory/iterator.hpp"
36 #include "memory/resourceArea.hpp"
37 #include "nmt/memTracker.hpp"
38 #include "oops/oop.inline.hpp"
39 #include "runtime/atomicAccess.hpp"
40 #include "runtime/handles.inline.hpp"
41 #include "runtime/javaThread.inline.hpp"
42 #include "runtime/nonJavaThread.hpp"
43 #include "runtime/orderAccess.hpp"
44 #include "runtime/osThread.hpp"
45 #include "runtime/safepoint.hpp"
46 #include "runtime/safepointMechanism.inline.hpp"
47 #include "runtime/thread.inline.hpp"
48 #include "runtime/threadSMR.inline.hpp"
49 #include "utilities/macros.hpp"
50 #include "utilities/spinYield.hpp"
51 #if INCLUDE_JFR
52 #include "jfr/jfr.hpp"
53 #endif
54
55 THREAD_LOCAL Thread* Thread::_thr_current = nullptr;
56
57 // ======= Thread ========
58 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
59 // JavaThread
60
61 Thread::Thread(MemTag mem_tag) {
62
63 DEBUG_ONLY(_run_state = PRE_CALL_RUN;)
64
65 // stack and get_thread
66 set_stack_base(nullptr);
67 set_stack_size(0);
68 DEBUG_ONLY(clear_suspendible_thread();)
69 DEBUG_ONLY(clear_indirectly_suspendible_thread();)
70 DEBUG_ONLY(clear_indirectly_safepoint_thread();)
71
72 // allocated data structures
73 set_osthread(nullptr);
74 set_resource_area(new (mem_tag) ResourceArea(mem_tag));
75 DEBUG_ONLY(_current_resource_mark = nullptr;)
76 set_handle_area(new (mem_tag) HandleArea(mem_tag));
77 set_metadata_handles(new (mtClass) GrowableArray<Metadata*>(30, mtClass));
78 set_last_handle_mark(nullptr);
79
80 // Initial value of zero ==> never claimed.
81 _threads_do_token = 0;
82 _threads_hazard_ptr = nullptr;
83 _threads_list_ptr = nullptr;
84 _nested_threads_hazard_ptr_cnt = 0;
85 _rcu_counter = 0;
86
87 // the handle mark links itself to last_handle_mark
88 new HandleMark(this);
89
90 // plain initialization
91 DEBUG_ONLY(_owned_locks = nullptr;)
92 NOT_PRODUCT(_skip_gcalot = false;)
93 _jvmti_env_iteration_count = 0;
94 set_allocated_bytes(0);
95 _current_pending_raw_monitor = nullptr;
96 _vm_error_callbacks = nullptr;
97
98 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
99 // If we are dumping, keep ihashes constant. Note that during dumping we only
100 // ever run one java thread, and no other thread should generate ihashes either,
101 // so using a constant seed should work fine.
102 _hashStateX = CDSConfig::is_dumping_static_archive() ? 0x12345678 : os::random();
103 _hashStateY = 842502087;
104 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
105 _hashStateW = 273326509;
106
107 // Many of the following fields are effectively final - immutable
108 // Note that nascent threads can't use the Native Monitor-Mutex
109 // construct until the _MutexEvent is initialized ...
110 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
111 // we might instead use a stack of ParkEvents that we could provision on-demand.
112 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
113 // and ::Release()
114 _ParkEvent = ParkEvent::Allocate(this);
115
116 #ifdef CHECK_UNHANDLED_OOPS
117 if (CheckUnhandledOops) {
118 _unhandled_oops = new UnhandledOops(this);
119 }
120 #endif // CHECK_UNHANDLED_OOPS
121
122 // Notify the barrier set that a thread is being created. The initial
123 // thread is created before the barrier set is available. The call to
124 // BarrierSet::on_thread_create() for this thread is therefore deferred
125 // to BarrierSet::set_barrier_set().
126 BarrierSet* const barrier_set = BarrierSet::barrier_set();
127 if (barrier_set != nullptr) {
128 barrier_set->on_thread_create(this);
129 } else {
130 // Only the main thread should be created before the barrier set
131 // and that happens just before Thread::current is set. No other thread
132 // can attach as the VM is not created yet, so they can't execute this code.
133 // If the main thread creates other threads before the barrier set that is an error.
134 assert(Thread::current_or_null() == nullptr, "creating thread before barrier set");
135 }
136
137 MACOS_AARCH64_ONLY(DEBUG_ONLY(_wx_init = false));
138
139 _profile_vm_locks = false;
140 _profile_vm_calls = false;
141 _profile_vm_ops = false;
142 _profile_rt_calls = false;
143 _profile_upcalls = false;
144
145 _all_bc_counter_value = 0;
146 _clinit_bc_counter_value = 0;
147
148 _current_rt_call_timer = nullptr;
149 }
150
151 #ifdef ASSERT
152 address Thread::stack_base() const {
153 // Note: can't report Thread::name() here as that can require a ResourceMark which we
154 // can't use because this gets called too early in the thread initialization.
155 assert(_stack_base != nullptr, "Stack base not yet set for thread id:%d (0 if not set)",
156 osthread() != nullptr ? osthread()->thread_id() : 0);
157 return _stack_base;
158 }
159 #endif
160
161 void Thread::initialize_tlab() {
162 if (UseTLAB) {
163 tlab().initialize();
164 }
165 }
166
167 void Thread::retire_tlab(ThreadLocalAllocStats* stats) {
168 // Sampling and serviceability support
169 if (tlab().end() != nullptr) {
170 incr_allocated_bytes(tlab().used_bytes());
171 heap_sampler().retire_tlab(tlab().top());
172 }
173
174 // Retire the TLAB
175 tlab().retire(stats);
176 }
177
178 void Thread::fill_tlab(HeapWord* start, size_t pre_reserved, size_t new_size) {
179 // Thread allocation sampling support
180 heap_sampler().set_tlab_top_at_sample_start(start);
181
182 // Fill the TLAB
183 tlab().fill(start, start + pre_reserved, new_size);
184 }
185
186 void Thread::initialize_thread_current() {
187 assert(_thr_current == nullptr, "Thread::current already initialized");
188 _thr_current = this;
189 assert(ThreadLocalStorage::thread() == nullptr, "ThreadLocalStorage::thread already initialized");
190 ThreadLocalStorage::set_thread(this);
191 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
192 }
193
194 void Thread::clear_thread_current() {
195 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
196 _thr_current = nullptr;
197 ThreadLocalStorage::set_thread(nullptr);
198 }
199
200 void Thread::record_stack_base_and_size() {
201 // Note: at this point, Thread object is not yet initialized. Do not rely on
202 // any members being initialized. Do not rely on Thread::current() being set.
203 // If possible, refrain from doing anything which may crash or assert since
204 // quite probably those crash dumps will be useless.
205 address base;
206 size_t size;
207 os::current_stack_base_and_size(&base, &size);
208 set_stack_base(base);
209 set_stack_size(size);
210
211 // Set stack limits after thread is initialized.
212 if (is_Java_thread()) {
213 JavaThread::cast(this)->stack_overflow_state()->initialize(stack_base(), stack_end());
214 }
215 }
216
217 void Thread::register_thread_stack_with_NMT() {
218 MemTracker::record_thread_stack(stack_end(), stack_size());
219 }
220
221 void Thread::unregister_thread_stack_with_NMT() {
222 MemTracker::release_thread_stack(stack_end(), stack_size());
223 }
224
225 void Thread::call_run() {
226 DEBUG_ONLY(_run_state = CALL_RUN;)
227
228 // At this point, Thread object should be fully initialized and
229 // Thread::current() should be set.
230
231 assert(Thread::current_or_null() != nullptr, "current thread is unset");
232 assert(Thread::current_or_null() == this, "current thread is wrong");
233
234 // Perform common initialization actions
235
236 MACOS_AARCH64_ONLY(this->init_wx());
237
238 register_thread_stack_with_NMT();
239
240 JFR_ONLY(Jfr::on_thread_start(this);)
241
242 log_debug(os, thread)("Thread %zu stack dimensions: "
243 PTR_FORMAT "-" PTR_FORMAT " (%zuk).",
244 os::current_thread_id(), p2i(stack_end()),
245 p2i(stack_base()), stack_size()/1024);
246
247 // Perform <ChildClass> initialization actions
248 DEBUG_ONLY(_run_state = PRE_RUN;)
249 this->pre_run();
250
251 // Invoke <ChildClass>::run()
252 DEBUG_ONLY(_run_state = RUN;)
253 this->run();
254 // Returned from <ChildClass>::run(). Thread finished.
255
256 // Perform common tear-down actions
257
258 assert(Thread::current_or_null() != nullptr, "current thread is unset");
259 assert(Thread::current_or_null() == this, "current thread is wrong");
260
261 // Perform <ChildClass> tear-down actions
262 DEBUG_ONLY(_run_state = POST_RUN;)
263 this->post_run();
264
265 // Note: at this point the thread object may already have deleted itself,
266 // so from here on do not dereference *this*. Not all thread types currently
267 // delete themselves when they terminate. But no thread should ever be deleted
268 // asynchronously with respect to its termination - that is what _run_state can
269 // be used to check.
270
271 // Logically we should do this->unregister_thread_stack_with_NMT() here, but we
272 // had to move that into post_run() because of the `this` deletion issue.
273
274 assert(Thread::current_or_null() == nullptr, "current thread still present");
275 }
276
277 Thread::~Thread() {
278
279 // Attached threads will remain in PRE_CALL_RUN, as will threads that don't actually
280 // get started due to errors etc. Any active thread should at least reach post_run
281 // before it is deleted (usually in post_run()).
282 assert(_run_state == PRE_CALL_RUN ||
283 _run_state == POST_RUN, "Active Thread deleted before post_run(): "
284 "_run_state=%d", (int)_run_state);
285
286 // Notify the barrier set that a thread is being destroyed. Note that a barrier
287 // set might not be available if we encountered errors during bootstrapping.
288 BarrierSet* const barrier_set = BarrierSet::barrier_set();
289 if (barrier_set != nullptr) {
290 barrier_set->on_thread_destroy(this);
291 }
292
293 // deallocate data structures
294 delete resource_area();
295 // since the handle marks are using the handle area, we have to deallocated the root
296 // handle mark before deallocating the thread's handle area,
297 assert(last_handle_mark() != nullptr, "check we have an element");
298 delete last_handle_mark();
299 assert(last_handle_mark() == nullptr, "check we have reached the end");
300
301 ParkEvent::Release(_ParkEvent);
302 // Set to null as a termination indicator for has_terminated().
303 AtomicAccess::store(&_ParkEvent, (ParkEvent*)nullptr);
304
305 delete handle_area();
306 delete metadata_handles();
307
308 // osthread() can be null, if creation of thread failed.
309 if (osthread() != nullptr) os::free_thread(osthread());
310
311 // Clear Thread::current if thread is deleting itself and it has not
312 // already been done. This must be done before the memory is deallocated.
313 // Needed to ensure JNI correctly detects non-attached threads.
314 if (this == Thread::current_or_null()) {
315 Thread::clear_thread_current();
316 }
317
318 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
319 }
320
321 #ifdef ASSERT
322 // A JavaThread is considered dangling if it not handshake-safe with respect to
323 // the current thread, it is not on a ThreadsList, or not at safepoint.
324 void Thread::check_for_dangling_thread_pointer(Thread *thread) {
325 assert(!thread->is_Java_thread() ||
326 JavaThread::cast(thread)->is_handshake_safe_for(Thread::current()) ||
327 !JavaThread::cast(thread)->on_thread_list() ||
328 SafepointSynchronize::is_at_safepoint() ||
329 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock(JavaThread::cast(thread)),
330 "possibility of dangling Thread pointer");
331 }
332 #endif
333
334 // Is the target JavaThread protected by the calling Thread or by some other
335 // mechanism?
336 //
337 bool Thread::is_JavaThread_protected(const JavaThread* target) {
338 Thread* current_thread = Thread::current();
339
340 // Do the simplest check first:
341 if (SafepointSynchronize::is_at_safepoint()) {
342 // The target is protected since JavaThreads cannot exit
343 // while we're at a safepoint.
344 return true;
345 }
346
347 // If the target hasn't been started yet then it is trivially
348 // "protected". We assume the caller is the thread that will do
349 // the starting.
350 if (target->osthread() == nullptr || target->osthread()->get_state() <= INITIALIZED) {
351 return true;
352 }
353
354 // Now make the simple checks based on who the caller is:
355 if (current_thread == target || Threads_lock->owner() == current_thread) {
356 // Target JavaThread is self or calling thread owns the Threads_lock.
357 // Second check is the same as Threads_lock->owner_is_self(),
358 // but we already have the current thread so check directly.
359 return true;
360 }
361
362 // Check the ThreadsLists associated with the calling thread (if any)
363 // to see if one of them protects the target JavaThread:
364 if (is_JavaThread_protected_by_TLH(target)) {
365 return true;
366 }
367
368 // Use this debug code with -XX:+UseNewCode to diagnose locations that
369 // are missing a ThreadsListHandle or other protection mechanism:
370 // guarantee(!UseNewCode, "current_thread=" INTPTR_FORMAT " is not protecting target="
371 // INTPTR_FORMAT, p2i(current_thread), p2i(target));
372
373 // Note: Since 'target' isn't protected by a TLH, the call to
374 // target->is_handshake_safe_for() may crash, but we have debug bits so
375 // we'll be able to figure out what protection mechanism is missing.
376 assert(target->is_handshake_safe_for(current_thread), "JavaThread=" INTPTR_FORMAT
377 " is not protected and not handshake safe.", p2i(target));
378
379 // The target JavaThread is not protected so it is not safe to query:
380 return false;
381 }
382
383 // Is the target JavaThread protected by a ThreadsListHandle (TLH) associated
384 // with the calling Thread?
385 //
386 bool Thread::is_JavaThread_protected_by_TLH(const JavaThread* target) {
387 Thread* current_thread = Thread::current();
388
389 // Check the ThreadsLists associated with the calling thread (if any)
390 // to see if one of them protects the target JavaThread:
391 for (SafeThreadsListPtr* stlp = current_thread->_threads_list_ptr;
392 stlp != nullptr; stlp = stlp->previous()) {
393 if (stlp->list()->includes(target)) {
394 // The target JavaThread is protected by this ThreadsList:
395 return true;
396 }
397 }
398
399 // The target JavaThread is not protected by a TLH so it is not safe to query:
400 return false;
401 }
402
403 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
404 DEBUG_ONLY(check_for_dangling_thread_pointer(thread);)
405 // Can return an error!
406 (void)os::set_priority(thread, priority);
407 }
408
409
410 void Thread::start(Thread* thread) {
411 // Start is different from resume in that its safety is guaranteed by context or
412 // being called from a Java method synchronized on the Thread object.
413 if (thread->is_Java_thread()) {
414 // Initialize the thread state to RUNNABLE before starting this thread.
415 // Can not set it after the thread started because we do not know the
416 // exact thread state at that time. It could be in MONITOR_WAIT or
417 // in SLEEPING or some other state.
418 java_lang_Thread::set_thread_status(JavaThread::cast(thread)->threadObj(),
419 JavaThreadStatus::RUNNABLE);
420 }
421 os::start_thread(thread);
422 }
423
424 // GC Support
425 bool Thread::claim_par_threads_do(uintx claim_token) {
426 uintx token = _threads_do_token;
427 if (token != claim_token) {
428 uintx res = AtomicAccess::cmpxchg(&_threads_do_token, token, claim_token);
429 if (res == token) {
430 return true;
431 }
432 guarantee(res == claim_token, "invariant");
433 }
434 return false;
435 }
436
437 void Thread::oops_do_no_frames(OopClosure* f, NMethodClosure* cf) {
438 // Do oop for ThreadShadow
439 f->do_oop((oop*)&_pending_exception);
440 handle_area()->oops_do(f);
441 }
442
443 // If the caller is a NamedThread, then remember, in the current scope,
444 // the given JavaThread in its _processed_thread field.
445 class RememberProcessedThread: public StackObj {
446 NamedThread* _cur_thr;
447 public:
448 RememberProcessedThread(Thread* thread) {
449 Thread* self = Thread::current();
450 if (self->is_Named_thread()) {
451 _cur_thr = (NamedThread *)self;
452 assert(_cur_thr->processed_thread() == nullptr, "nesting not supported");
453 _cur_thr->set_processed_thread(thread);
454 } else {
455 _cur_thr = nullptr;
456 }
457 }
458
459 ~RememberProcessedThread() {
460 if (_cur_thr) {
461 assert(_cur_thr->processed_thread() != nullptr, "nesting not supported");
462 _cur_thr->set_processed_thread(nullptr);
463 }
464 }
465 };
466
467 void Thread::oops_do(OopClosure* f, NMethodClosure* cf) {
468 // Record JavaThread to GC thread
469 RememberProcessedThread rpt(this);
470 oops_do_no_frames(f, cf);
471 oops_do_frames(f, cf);
472 }
473
474 void Thread::metadata_handles_do(void f(Metadata*)) {
475 // Only walk the Handles in Thread.
476 if (metadata_handles() != nullptr) {
477 for (int i = 0; i< metadata_handles()->length(); i++) {
478 f(metadata_handles()->at(i));
479 }
480 }
481 }
482
483 void Thread::print_on(outputStream* st, bool print_extended_info) const {
484 // get_priority assumes osthread initialized
485 if (osthread() != nullptr) {
486 int os_prio;
487 if (os::get_native_priority(this, &os_prio) == OS_OK) {
488 st->print("os_prio=%d ", os_prio);
489 }
490
491 st->print("cpu=%.2fms ",
492 (double)os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0
493 );
494 st->print("elapsed=%.2fs ",
495 (double)_statistical_info.getElapsedTime() / 1000.0
496 );
497 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) {
498 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes();
499 st->print("allocated=%zu%s ",
500 byte_size_in_proper_unit(allocated_bytes),
501 proper_unit_for_byte_size(allocated_bytes)
502 );
503 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount());
504 }
505
506 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
507 if (!is_Java_thread() || !JavaThread::cast(this)->is_vthread_mounted()) {
508 osthread()->print_on(st);
509 }
510 }
511 ThreadsSMRSupport::print_info_on(this, st);
512 st->print(" ");
513 DEBUG_ONLY(if (WizardMode) print_owned_locks_on(st);)
514 }
515
516 void Thread::print() const { print_on(tty); }
517
518 // Thread::print_on_error() is called by fatal error handler. Don't use
519 // any lock or allocate memory.
520 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
521 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
522
523 st->print("%s \"%s\"", type_name(), name());
524
525 OSThread* os_thr = osthread();
526 if (os_thr != nullptr) {
527 st->fill_to(67);
528 if (os_thr->get_state() != ZOMBIE) {
529 // Use raw field members for stack base/size as this could be
530 // called before a thread has run enough to initialize them.
531 st->print(" [id=%d, stack(" PTR_FORMAT "," PTR_FORMAT ") (" PROPERFMT ")]",
532 osthread()->thread_id(), p2i(_stack_base - _stack_size), p2i(_stack_base),
533 PROPERFMTARGS(_stack_size));
534 } else {
535 st->print(" terminated");
536 }
537 } else {
538 st->print(" unknown state (no osThread)");
539 }
540 ThreadsSMRSupport::print_info_on(this, st);
541 }
542
543 void Thread::print_value_on(outputStream* st) const {
544 if (is_Named_thread()) {
545 st->print(" \"%s\" ", name());
546 }
547 st->print(INTPTR_FORMAT, p2i(this)); // print address
548 }
549
550 #ifdef ASSERT
551 void Thread::print_owned_locks_on(outputStream* st) const {
552 Mutex* cur = _owned_locks;
553 if (cur == nullptr) {
554 st->print(" (no locks) ");
555 } else {
556 st->print_cr(" Locks owned:");
557 while (cur) {
558 cur->print_on(st);
559 cur = cur->next();
560 }
561 }
562 }
563
564 Thread* Thread::_starting_thread = nullptr;
565
566 bool Thread::is_starting_thread(const Thread* t) {
567 assert(_starting_thread != nullptr, "invariant");
568 return t == _starting_thread;
569 }
570 #endif // ASSERT
571
572 bool Thread::set_as_starting_thread(JavaThread* jt) {
573 assert(jt != nullptr, "invariant");
574 assert(_starting_thread == nullptr, "already initialized: "
575 "_starting_thread=" INTPTR_FORMAT, p2i(_starting_thread));
576 // NOTE: this must be called from Threads::create_vm().
577 DEBUG_ONLY(_starting_thread = jt;)
578 return os::create_main_thread(jt);
579 }
580
581 // Ad-hoc mutual exclusion primitive: spin lock
582 //
583 // We employ a spin lock _only for low-contention, fixed-length
584 // short-duration critical sections where we're concerned
585 // about native mutex_t or HotSpot Mutex:: latency.
586
587 void Thread::SpinAcquire(volatile int * adr) {
588 if (AtomicAccess::cmpxchg(adr, 0, 1) == 0) {
589 return; // normal fast-path return
590 }
591
592 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
593 int ctr = 0;
594 int Yields = 0;
595 for (;;) {
596 while (*adr != 0) {
597 ++ctr;
598 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
599 if (Yields > 5) {
600 os::naked_short_sleep(1);
601 } else {
602 os::naked_yield();
603 ++Yields;
604 }
605 } else {
606 SpinPause();
607 }
608 }
609 if (AtomicAccess::cmpxchg(adr, 0, 1) == 0) return;
610 }
611 }
612
613 void Thread::SpinRelease(volatile int * adr) {
614 assert(*adr != 0, "invariant");
615 // Roach-motel semantics.
616 // It's safe if subsequent LDs and STs float "up" into the critical section,
617 // but prior LDs and STs within the critical section can't be allowed
618 // to reorder or float past the ST that releases the lock.
619 // Loads and stores in the critical section - which appear in program
620 // order before the store that releases the lock - must also appear
621 // before the store that releases the lock in memory visibility order.
622 // So we need a #loadstore|#storestore "release" memory barrier before
623 // the ST of 0 into the lock-word which releases the lock.
624 AtomicAccess::release_store(adr, 0);
625 }
626
627 const char* ProfileVMCallContext::name(PerfTraceTime* t) {
628 return t->name();
629 }
630
631 int ProfileVMCallContext::_perf_nested_runtime_calls_count = 0;
632
633 void ProfileVMCallContext::notify_nested_rt_call(PerfTraceTime* outer_timer, PerfTraceTime* inner_timer) {
634 log_debug(init)("Nested runtime call: inner=%s outer=%s", inner_timer->name(), outer_timer->name());
635 AtomicAccess::inc(&ProfileVMCallContext::_perf_nested_runtime_calls_count);
636 }
637