1 /*
   2  * Copyright (c) 1997, 2024, 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 "precompiled.hpp"
  27 #include "cds/dynamicArchive.hpp"
  28 #include "ci/ciEnv.hpp"
  29 #include "classfile/javaClasses.inline.hpp"
  30 #include "classfile/javaThreadStatus.hpp"
  31 #include "classfile/systemDictionary.hpp"
  32 #include "classfile/vmClasses.hpp"
  33 #include "classfile/vmSymbols.hpp"
  34 #include "code/codeCache.hpp"
  35 #include "code/scopeDesc.hpp"
  36 #include "compiler/compileTask.hpp"
  37 #include "compiler/compilerThread.hpp"
  38 #include "gc/shared/oopStorage.hpp"
  39 #include "gc/shared/oopStorageSet.hpp"
  40 #include "gc/shared/tlab_globals.hpp"
  41 #include "jfr/jfrEvents.hpp"
  42 #include "jvm.h"
  43 #include "jvmtifiles/jvmtiEnv.hpp"
  44 #include "logging/log.hpp"
  45 #include "logging/logAsyncWriter.hpp"
  46 #include "logging/logStream.hpp"
  47 #include "memory/allocation.inline.hpp"
  48 #include "memory/iterator.hpp"
  49 #include "memory/universe.hpp"
  50 #include "oops/access.inline.hpp"
  51 #include "oops/instanceKlass.hpp"
  52 #include "oops/klass.inline.hpp"
  53 #include "oops/oop.inline.hpp"
  54 #include "oops/oopHandle.inline.hpp"
  55 #include "oops/verifyOopClosure.hpp"
  56 #include "prims/jvm_misc.hpp"
  57 #include "prims/jvmtiDeferredUpdates.hpp"
  58 #include "prims/jvmtiExport.hpp"
  59 #include "prims/jvmtiThreadState.inline.hpp"
  60 #include "runtime/atomic.hpp"
  61 #include "runtime/continuation.hpp"
  62 #include "runtime/continuationEntry.inline.hpp"
  63 #include "runtime/continuationHelper.inline.hpp"
  64 #include "runtime/deoptimization.hpp"
  65 #include "runtime/frame.inline.hpp"
  66 #include "runtime/handles.inline.hpp"
  67 #include "runtime/handshake.hpp"
  68 #include "runtime/interfaceSupport.inline.hpp"
  69 #include "runtime/java.hpp"
  70 #include "runtime/javaCalls.hpp"
  71 #include "runtime/javaThread.inline.hpp"
  72 #include "runtime/jniHandles.inline.hpp"
  73 #include "runtime/lockStack.inline.hpp"
  74 #include "runtime/mutexLocker.hpp"
  75 #include "runtime/orderAccess.hpp"
  76 #include "runtime/os.inline.hpp"
  77 #include "runtime/osThread.hpp"
  78 #include "runtime/safepoint.hpp"
  79 #include "runtime/safepointMechanism.inline.hpp"
  80 #include "runtime/safepointVerifiers.hpp"
  81 #include "runtime/serviceThread.hpp"
  82 #include "runtime/stackFrameStream.inline.hpp"
  83 #include "runtime/stackWatermarkSet.hpp"
  84 #include "runtime/synchronizer.hpp"
  85 #include "runtime/threadCritical.hpp"
  86 #include "runtime/threadIdentifier.hpp"
  87 #include "runtime/threadSMR.inline.hpp"
  88 #include "runtime/threadStatisticalInfo.hpp"
  89 #include "runtime/threadWXSetters.inline.hpp"
  90 #include "runtime/timer.hpp"
  91 #include "runtime/timerTrace.hpp"
  92 #include "runtime/vframe.inline.hpp"
  93 #include "runtime/vframeArray.hpp"
  94 #include "runtime/vframe_hp.hpp"
  95 #include "runtime/vmThread.hpp"
  96 #include "runtime/vmOperations.hpp"
  97 #include "services/threadService.hpp"
  98 #include "utilities/copy.hpp"
  99 #include "utilities/defaultStream.hpp"
 100 #include "utilities/dtrace.hpp"
 101 #include "utilities/events.hpp"
 102 #include "utilities/macros.hpp"
 103 #include "utilities/preserveException.hpp"
 104 #include "utilities/spinYield.hpp"
 105 #include "utilities/vmError.hpp"
 106 #if INCLUDE_JVMCI
 107 #include "jvmci/jvmci.hpp"
 108 #include "jvmci/jvmciEnv.hpp"
 109 #endif
 110 #if INCLUDE_JFR
 111 #include "jfr/jfr.hpp"
 112 #endif
 113 
 114 // Set by os layer.
 115 size_t      JavaThread::_stack_size_at_create = 0;
 116 
 117 #ifdef DTRACE_ENABLED
 118 
 119 // Only bother with this argument setup if dtrace is available
 120 
 121   #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
 122   #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
 123 
 124   #define DTRACE_THREAD_PROBE(probe, javathread)                           \
 125     {                                                                      \
 126       ResourceMark rm(this);                                               \
 127       int len = 0;                                                         \
 128       const char* name = (javathread)->name();                             \
 129       len = strlen(name);                                                  \
 130       HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */               \
 131         (char *) name, len,                                                \
 132         java_lang_Thread::thread_id((javathread)->threadObj()),            \
 133         (uintptr_t) (javathread)->osthread()->thread_id(),                 \
 134         java_lang_Thread::is_daemon((javathread)->threadObj()));           \
 135     }
 136 
 137 #else //  ndef DTRACE_ENABLED
 138 
 139   #define DTRACE_THREAD_PROBE(probe, javathread)
 140 
 141 #endif // ndef DTRACE_ENABLED
 142 
 143 void JavaThread::smr_delete() {
 144   if (_on_thread_list) {
 145     ThreadsSMRSupport::smr_delete(this);
 146   } else {
 147     delete this;
 148   }
 149 }
 150 
 151 // Initialized by VMThread at vm_global_init
 152 OopStorage* JavaThread::_thread_oop_storage = nullptr;
 153 
 154 OopStorage* JavaThread::thread_oop_storage() {
 155   assert(_thread_oop_storage != nullptr, "not yet initialized");
 156   return _thread_oop_storage;
 157 }
 158 
 159 void JavaThread::set_threadOopHandles(oop p) {
 160   assert(_thread_oop_storage != nullptr, "not yet initialized");
 161   _threadObj   = OopHandle(_thread_oop_storage, p);
 162   _vthread     = OopHandle(_thread_oop_storage, p);
 163   _jvmti_vthread = OopHandle(_thread_oop_storage, p->is_a(vmClasses::BoundVirtualThread_klass()) ? p : nullptr);
 164   _scopedValueCache = OopHandle(_thread_oop_storage, nullptr);
 165 }
 166 
 167 oop JavaThread::threadObj() const {
 168   // Ideally we would verify the current thread is oop_safe when this is called, but as we can
 169   // be called from a signal handler we would have to use Thread::current_or_null_safe(). That
 170   // has overhead and also interacts poorly with GetLastError on Windows due to the use of TLS.
 171   // Instead callers must verify oop safe access.
 172   return _threadObj.resolve();
 173 }
 174 
 175 oop JavaThread::vthread() const {
 176   return _vthread.resolve();
 177 }
 178 
 179 void JavaThread::set_vthread(oop p) {
 180   assert(_thread_oop_storage != nullptr, "not yet initialized");
 181   _vthread.replace(p);
 182 }
 183 
 184 oop JavaThread::jvmti_vthread() const {
 185   return _jvmti_vthread.resolve();
 186 }
 187 
 188 void JavaThread::set_jvmti_vthread(oop p) {
 189   assert(_thread_oop_storage != nullptr, "not yet initialized");
 190   _jvmti_vthread.replace(p);
 191 }
 192 
 193 oop JavaThread::scopedValueCache() const {
 194   return _scopedValueCache.resolve();
 195 }
 196 
 197 void JavaThread::set_scopedValueCache(oop p) {
 198   if (!_scopedValueCache.is_empty()) { // i.e. if the OopHandle has been allocated
 199     _scopedValueCache.replace(p);
 200   } else {
 201     assert(p == nullptr, "not yet initialized");
 202   }
 203 }
 204 
 205 void JavaThread::clear_scopedValueBindings() {
 206   set_scopedValueCache(nullptr);
 207   oop vthread_oop = vthread();
 208   // vthread may be null here if we get a VM error during startup,
 209   // before the java.lang.Thread instance has been created.
 210   if (vthread_oop != nullptr) {
 211     java_lang_Thread::clear_scopedValueBindings(vthread_oop);
 212   }
 213 }
 214 
 215 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
 216                                     bool daemon, TRAPS) {
 217   assert(thread_group.not_null(), "thread group should be specified");
 218   assert(threadObj() == nullptr, "should only create Java thread object once");
 219 
 220   InstanceKlass* ik = vmClasses::Thread_klass();
 221   assert(ik->is_initialized(), "must be");
 222   instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
 223 
 224   // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
 225   // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
 226   // constructor calls Thread.current(), which must be set here.
 227   java_lang_Thread::set_thread(thread_oop(), this);
 228   set_threadOopHandles(thread_oop());
 229   // Set the lock_id to the next thread_id temporarily while initialization runs.
 230   set_lock_id(ThreadIdentifier::next());
 231 
 232   JavaValue result(T_VOID);
 233   if (thread_name != nullptr) {
 234     Handle name = java_lang_String::create_from_str(thread_name, CHECK);
 235     // Thread gets assigned specified name and null target
 236     JavaCalls::call_special(&result,
 237                             thread_oop,
 238                             ik,
 239                             vmSymbols::object_initializer_name(),
 240                             vmSymbols::threadgroup_string_void_signature(),
 241                             thread_group,
 242                             name,
 243                             CHECK);
 244   } else {
 245     // Thread gets assigned name "Thread-nnn" and null target
 246     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
 247     JavaCalls::call_special(&result,
 248                             thread_oop,
 249                             ik,
 250                             vmSymbols::object_initializer_name(),
 251                             vmSymbols::threadgroup_runnable_void_signature(),
 252                             thread_group,
 253                             Handle(),
 254                             CHECK);
 255   }
 256   // Update the lock_id with the tid value.
 257   set_lock_id(java_lang_Thread::thread_id(thread_oop()));
 258 
 259   os::set_priority(this, NormPriority);
 260 
 261   if (daemon) {
 262     java_lang_Thread::set_daemon(thread_oop());
 263   }
 264 }
 265 
 266 // ======= JavaThread ========
 267 
 268 #if INCLUDE_JVMCI
 269 
 270 jlong* JavaThread::_jvmci_old_thread_counters;
 271 
 272 static bool jvmci_counters_include(JavaThread* thread) {
 273   return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
 274 }
 275 
 276 void JavaThread::collect_counters(jlong* array, int length) {
 277   assert(length == JVMCICounterSize, "wrong value");
 278   for (int i = 0; i < length; i++) {
 279     array[i] = _jvmci_old_thread_counters[i];
 280   }
 281   for (JavaThread* tp : ThreadsListHandle()) {
 282     if (jvmci_counters_include(tp)) {
 283       for (int i = 0; i < length; i++) {
 284         array[i] += tp->_jvmci_counters[i];
 285       }
 286     }
 287   }
 288 }
 289 
 290 // Attempt to enlarge the array for per thread counters.
 291 static jlong* resize_counters_array(jlong* old_counters, int current_size, int new_size) {
 292   jlong* new_counters = NEW_C_HEAP_ARRAY_RETURN_NULL(jlong, new_size, mtJVMCI);
 293   if (new_counters == nullptr) {
 294     return nullptr;
 295   }
 296   if (old_counters == nullptr) {
 297     old_counters = new_counters;
 298     memset(old_counters, 0, sizeof(jlong) * new_size);
 299   } else {
 300     for (int i = 0; i < MIN2((int) current_size, new_size); i++) {
 301       new_counters[i] = old_counters[i];
 302     }
 303     if (new_size > current_size) {
 304       memset(new_counters + current_size, 0, sizeof(jlong) * (new_size - current_size));
 305     }
 306     FREE_C_HEAP_ARRAY(jlong, old_counters);
 307   }
 308   return new_counters;
 309 }
 310 
 311 // Attempt to enlarge the array for per thread counters.
 312 bool JavaThread::resize_counters(int current_size, int new_size) {
 313   jlong* new_counters = resize_counters_array(_jvmci_counters, current_size, new_size);
 314   if (new_counters == nullptr) {
 315     return false;
 316   } else {
 317     _jvmci_counters = new_counters;
 318     return true;
 319   }
 320 }
 321 
 322 class VM_JVMCIResizeCounters : public VM_Operation {
 323  private:
 324   int _new_size;
 325   bool _failed;
 326 
 327  public:
 328   VM_JVMCIResizeCounters(int new_size) : _new_size(new_size), _failed(false) { }
 329   VMOp_Type type()                  const        { return VMOp_JVMCIResizeCounters; }
 330   bool allow_nested_vm_operations() const        { return true; }
 331   void doit() {
 332     // Resize the old thread counters array
 333     jlong* new_counters = resize_counters_array(JavaThread::_jvmci_old_thread_counters, JVMCICounterSize, _new_size);
 334     if (new_counters == nullptr) {
 335       _failed = true;
 336       return;
 337     } else {
 338       JavaThread::_jvmci_old_thread_counters = new_counters;
 339     }
 340 
 341     // Now resize each threads array
 342     for (JavaThread* tp : ThreadsListHandle()) {
 343       if (!tp->resize_counters(JVMCICounterSize, _new_size)) {
 344         _failed = true;
 345         break;
 346       }
 347     }
 348     if (!_failed) {
 349       JVMCICounterSize = _new_size;
 350     }
 351   }
 352 
 353   bool failed() { return _failed; }
 354 };
 355 
 356 bool JavaThread::resize_all_jvmci_counters(int new_size) {
 357   VM_JVMCIResizeCounters op(new_size);
 358   VMThread::execute(&op);
 359   return !op.failed();
 360 }
 361 
 362 #endif // INCLUDE_JVMCI
 363 
 364 #ifdef ASSERT
 365 // Checks safepoint allowed and clears unhandled oops at potential safepoints.
 366 void JavaThread::check_possible_safepoint() {
 367   if (_no_safepoint_count > 0) {
 368     print_owned_locks();
 369     assert(false, "Possible safepoint reached by thread that does not allow it");
 370   }
 371 #ifdef CHECK_UNHANDLED_OOPS
 372   // Clear unhandled oops in JavaThreads so we get a crash right away.
 373   clear_unhandled_oops();
 374 #endif // CHECK_UNHANDLED_OOPS
 375 
 376   // Macos/aarch64 should be in the right state for safepoint (e.g.
 377   // deoptimization needs WXWrite).  Crashes caused by the wrong state rarely
 378   // happens in practice, making such issues hard to find and reproduce.
 379 #if defined(__APPLE__) && defined(AARCH64)
 380   if (AssertWXAtThreadSync) {
 381     assert_wx_state(WXWrite);
 382   }
 383 #endif
 384 }
 385 
 386 void JavaThread::check_for_valid_safepoint_state() {
 387   // Don't complain if running a debugging command.
 388   if (DebuggingContext::is_enabled()) return;
 389 
 390   // Check NoSafepointVerifier, which is implied by locks taken that can be
 391   // shared with the VM thread.  This makes sure that no locks with allow_vm_block
 392   // are held.
 393   check_possible_safepoint();
 394 
 395   if (thread_state() != _thread_in_vm) {
 396     fatal("LEAF method calling lock?");
 397   }
 398 
 399   if (GCALotAtAllSafepoints) {
 400     // We could enter a safepoint here and thus have a gc
 401     InterfaceSupport::check_gc_alot();
 402   }
 403 }
 404 #endif // ASSERT
 405 
 406 // A JavaThread is a normal Java thread
 407 
 408 JavaThread::JavaThread() :
 409   // Initialize fields
 410 
 411   _on_thread_list(false),
 412   DEBUG_ONLY(_java_call_counter(0) COMMA)
 413   _entry_point(nullptr),
 414   _deopt_mark(nullptr),
 415   _deopt_nmethod(nullptr),
 416   _vframe_array_head(nullptr),
 417   _vframe_array_last(nullptr),
 418   _jvmti_deferred_updates(nullptr),
 419   _callee_target(nullptr),
 420   _vm_result(nullptr),
 421   _vm_result_2(nullptr),
 422 
 423   _current_pending_monitor(nullptr),
 424   _current_pending_monitor_is_from_java(true),
 425   _current_waiting_monitor(nullptr),
 426   _active_handles(nullptr),
 427   _free_handle_block(nullptr),
 428   _lock_id(0),
 429   _Stalled(0),
 430   _on_monitorenter(false),
 431 
 432   _monitor_chunks(nullptr),
 433 
 434   _suspend_flags(0),
 435 
 436   _thread_state(_thread_new),
 437   _saved_exception_pc(nullptr),
 438 #ifdef ASSERT
 439   _no_safepoint_count(0),
 440   _visited_for_critical_count(false),
 441 #endif
 442 
 443   _terminated(_not_terminated),
 444   _in_deopt_handler(0),
 445   _doing_unsafe_access(false),
 446   _do_not_unlock_if_synchronized(false),
 447 #if INCLUDE_JVMTI
 448   _carrier_thread_suspended(false),
 449   _is_in_VTMS_transition(false),
 450   _is_in_tmp_VTMS_transition(false),
 451   _is_disable_suspend(false),
 452 #ifdef ASSERT
 453   _is_VTMS_transition_disabler(false),
 454 #endif
 455 #endif
 456   _jni_attach_state(_not_attaching_via_jni),
 457 #if INCLUDE_JVMCI
 458   _pending_deoptimization(-1),
 459   _pending_monitorenter(false),
 460   _pending_transfer_to_interpreter(false),
 461   _in_retryable_allocation(false),
 462   _pending_failed_speculation(0),
 463   _jvmci{nullptr},
 464   _libjvmci_runtime(nullptr),
 465   _jvmci_counters(nullptr),
 466   _jvmci_reserved0(0),
 467   _jvmci_reserved1(0),
 468   _jvmci_reserved_oop0(nullptr),
 469 #endif // INCLUDE_JVMCI
 470 
 471   _exception_oop(oop()),
 472   _exception_pc(0),
 473   _exception_handler_pc(0),
 474   _is_method_handle_return(0),
 475 
 476   _jni_active_critical(0),
 477   _pending_jni_exception_check_fn(nullptr),
 478   _depth_first_number(0),
 479 
 480   // JVMTI PopFrame support
 481   _popframe_condition(popframe_inactive),
 482   _frames_to_pop_failed_realloc(0),
 483 
 484   _cont_entry(nullptr),
 485   _cont_fastpath(0),
 486   _cont_fastpath_thread_state(1),
 487   _held_monitor_count(0),
 488   _jni_monitor_count(0),
 489   _preempting(false),
 490   _preemption_cancelled(false),
 491   _jvmti_unmount_event_pending(false),
 492   DEBUG_ONLY(_obj_locker_count(0) COMMA)
 493 
 494   _handshake(this),
 495 
 496   _popframe_preserved_args(nullptr),
 497   _popframe_preserved_args_size(0),
 498 
 499   _jvmti_thread_state(nullptr),
 500   _interp_only_mode(0),
 501   _should_post_on_exceptions_flag(JNI_FALSE),
 502   _thread_stat(new ThreadStatistics()),
 503 
 504   _parker(),
 505 
 506   _class_to_be_initialized(nullptr),
 507 
 508   _SleepEvent(ParkEvent::Allocate(this)),
 509 
 510   _lock_stack(this) {
 511   set_jni_functions(jni_functions());
 512 
 513 #if INCLUDE_JVMCI
 514   assert(_jvmci._implicit_exception_pc == nullptr, "must be");
 515   if (JVMCICounterSize > 0) {
 516     resize_counters(0, (int) JVMCICounterSize);
 517   }
 518 #endif // INCLUDE_JVMCI
 519 
 520   // Setup safepoint state info for this thread
 521   ThreadSafepointState::create(this);
 522 
 523   SafepointMechanism::initialize_header(this);
 524 
 525   set_requires_cross_modify_fence(false);
 526 
 527   pd_initialize();
 528   assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
 529 }
 530 
 531 JavaThread::JavaThread(bool is_attaching_via_jni) : JavaThread() {
 532   if (is_attaching_via_jni) {
 533     _jni_attach_state = _attaching_via_jni;
 534   }
 535 }
 536 
 537 
 538 // interrupt support
 539 
 540 void JavaThread::interrupt() {
 541   // All callers should have 'this' thread protected by a
 542   // ThreadsListHandle so that it cannot terminate and deallocate
 543   // itself.
 544   debug_only(check_for_dangling_thread_pointer(this);)
 545 
 546   // For Windows _interrupt_event
 547   WINDOWS_ONLY(osthread()->set_interrupted(true);)
 548 
 549   // For Thread.sleep
 550   _SleepEvent->unpark();
 551 
 552   // For JSR166 LockSupport.park
 553   parker()->unpark();
 554 
 555   // For ObjectMonitor and JvmtiRawMonitor
 556   _ParkEvent->unpark();
 557 }
 558 
 559 
 560 bool JavaThread::is_interrupted(bool clear_interrupted) {
 561   debug_only(check_for_dangling_thread_pointer(this);)
 562 
 563   if (_threadObj.peek() == nullptr) {
 564     // If there is no j.l.Thread then it is impossible to have
 565     // been interrupted. We can find null during VM initialization
 566     // or when a JNI thread is still in the process of attaching.
 567     // In such cases this must be the current thread.
 568     assert(this == Thread::current(), "invariant");
 569     return false;
 570   }
 571 
 572   bool interrupted = java_lang_Thread::interrupted(threadObj());
 573 
 574   // NOTE that since there is no "lock" around the interrupt and
 575   // is_interrupted operations, there is the possibility that the
 576   // interrupted flag will be "false" but that the
 577   // low-level events will be in the signaled state. This is
 578   // intentional. The effect of this is that Object.wait() and
 579   // LockSupport.park() will appear to have a spurious wakeup, which
 580   // is allowed and not harmful, and the possibility is so rare that
 581   // it is not worth the added complexity to add yet another lock.
 582   // For the sleep event an explicit reset is performed on entry
 583   // to JavaThread::sleep, so there is no early return. It has also been
 584   // recommended not to put the interrupted flag into the "event"
 585   // structure because it hides the issue.
 586   // Also, because there is no lock, we must only clear the interrupt
 587   // state if we are going to report that we were interrupted; otherwise
 588   // an interrupt that happens just after we read the field would be lost.
 589   if (interrupted && clear_interrupted) {
 590     assert(this == Thread::current(), "only the current thread can clear");
 591     java_lang_Thread::set_interrupted(threadObj(), false);
 592     WINDOWS_ONLY(osthread()->set_interrupted(false);)
 593   }
 594 
 595   return interrupted;
 596 }
 597 
 598 void JavaThread::block_if_vm_exited() {
 599   if (_terminated == _vm_exited) {
 600     // _vm_exited is set at safepoint, and Threads_lock is never released
 601     // so we will block here forever.
 602     // Here we can be doing a jump from a safe state to an unsafe state without
 603     // proper transition, but it happens after the final safepoint has begun so
 604     // this jump won't cause any safepoint problems.
 605     set_thread_state(_thread_in_vm);
 606     Threads_lock->lock();
 607     ShouldNotReachHere();
 608   }
 609 }
 610 
 611 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : JavaThread() {
 612   _jni_attach_state = _not_attaching_via_jni;
 613   set_entry_point(entry_point);
 614   // Create the native thread itself.
 615   // %note runtime_23
 616   os::ThreadType thr_type = os::java_thread;
 617   thr_type = entry_point == &CompilerThread::thread_entry ? os::compiler_thread :
 618                                                             os::java_thread;
 619   os::create_thread(this, thr_type, stack_sz);
 620   // The _osthread may be null here because we ran out of memory (too many threads active).
 621   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
 622   // may hold a lock and all locks must be unlocked before throwing the exception (throwing
 623   // the exception consists of creating the exception object & initializing it, initialization
 624   // will leave the VM via a JavaCall and then all locks must be unlocked).
 625   //
 626   // The thread is still suspended when we reach here. Thread must be explicit started
 627   // by creator! Furthermore, the thread must also explicitly be added to the Threads list
 628   // by calling Threads:add. The reason why this is not done here, is because the thread
 629   // object must be fully initialized (take a look at JVM_Start)
 630 }
 631 
 632 JavaThread::~JavaThread() {
 633 
 634   // Enqueue OopHandles for release by the service thread.
 635   add_oop_handles_for_release();
 636 
 637   // Return the sleep event to the free list
 638   ParkEvent::Release(_SleepEvent);
 639   _SleepEvent = nullptr;
 640 
 641   // Free any remaining  previous UnrollBlock
 642   vframeArray* old_array = vframe_array_last();
 643 
 644   if (old_array != nullptr) {
 645     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
 646     old_array->set_unroll_block(nullptr);
 647     delete old_info;
 648     delete old_array;
 649   }
 650 
 651   JvmtiDeferredUpdates* updates = deferred_updates();
 652   if (updates != nullptr) {
 653     // This can only happen if thread is destroyed before deoptimization occurs.
 654     assert(updates->count() > 0, "Updates holder not deleted");
 655     // free deferred updates.
 656     delete updates;
 657     set_deferred_updates(nullptr);
 658   }
 659 
 660   // All Java related clean up happens in exit
 661   ThreadSafepointState::destroy(this);
 662   if (_thread_stat != nullptr) delete _thread_stat;
 663 
 664 #if INCLUDE_JVMCI
 665   if (JVMCICounterSize > 0) {
 666     FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
 667   }
 668 #endif // INCLUDE_JVMCI
 669 }
 670 
 671 
 672 // First JavaThread specific code executed by a new Java thread.
 673 void JavaThread::pre_run() {
 674   // empty - see comments in run()
 675 }
 676 
 677 // The main routine called by a new Java thread. This isn't overridden
 678 // by subclasses, instead different subclasses define a different "entry_point"
 679 // which defines the actual logic for that kind of thread.
 680 void JavaThread::run() {
 681   // initialize thread-local alloc buffer related fields
 682   initialize_tlab();
 683 
 684   _stack_overflow_state.create_stack_guard_pages();
 685 
 686   cache_global_variables();
 687 
 688   // Thread is now sufficiently initialized to be handled by the safepoint code as being
 689   // in the VM. Change thread state from _thread_new to _thread_in_vm
 690   assert(this->thread_state() == _thread_new, "wrong thread state");
 691   set_thread_state(_thread_in_vm);
 692 
 693   // Before a thread is on the threads list it is always safe, so after leaving the
 694   // _thread_new we should emit a instruction barrier. The distance to modified code
 695   // from here is probably far enough, but this is consistent and safe.
 696   OrderAccess::cross_modify_fence();
 697 
 698   assert(JavaThread::current() == this, "sanity check");
 699   assert(!Thread::current()->owns_locks(), "sanity check");
 700 
 701   DTRACE_THREAD_PROBE(start, this);
 702 
 703   // This operation might block. We call that after all safepoint checks for a new thread has
 704   // been completed.
 705   set_active_handles(JNIHandleBlock::allocate_block());
 706 
 707   if (JvmtiExport::should_post_thread_life()) {
 708     JvmtiExport::post_thread_start(this);
 709 
 710   }
 711 
 712   if (AlwaysPreTouchStacks) {
 713     pretouch_stack();
 714   }
 715 
 716   // We call another function to do the rest so we are sure that the stack addresses used
 717   // from there will be lower than the stack base just computed.
 718   thread_main_inner();
 719 }
 720 
 721 void JavaThread::thread_main_inner() {
 722   assert(JavaThread::current() == this, "sanity check");
 723   assert(_threadObj.peek() != nullptr, "just checking");
 724 
 725   // Execute thread entry point unless this thread has a pending exception.
 726   // Note: Due to JVMTI StopThread we can have pending exceptions already!
 727   if (!this->has_pending_exception()) {
 728     {
 729       ResourceMark rm(this);
 730       this->set_native_thread_name(this->name());
 731     }
 732     HandleMark hm(this);
 733     this->entry_point()(this, this);
 734   }
 735 
 736   DTRACE_THREAD_PROBE(stop, this);
 737 
 738   // Cleanup is handled in post_run()
 739 }
 740 
 741 // Shared teardown for all JavaThreads
 742 void JavaThread::post_run() {
 743   this->exit(false);
 744   this->unregister_thread_stack_with_NMT();
 745   // Defer deletion to here to ensure 'this' is still referenceable in call_run
 746   // for any shared tear-down.
 747   this->smr_delete();
 748 }
 749 
 750 static void ensure_join(JavaThread* thread) {
 751   // We do not need to grab the Threads_lock, since we are operating on ourself.
 752   Handle threadObj(thread, thread->threadObj());
 753   assert(threadObj.not_null(), "java thread object must exist");
 754   ObjectLocker lock(threadObj, thread);
 755   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
 756   java_lang_Thread::set_thread_status(threadObj(), JavaThreadStatus::TERMINATED);
 757   // Clear the native thread instance - this makes isAlive return false and allows the join()
 758   // to complete once we've done the notify_all below. Needs a release() to obey Java Memory Model
 759   // requirements.
 760   assert(java_lang_Thread::thread(threadObj()) == thread, "must be alive");
 761   java_lang_Thread::release_set_thread(threadObj(), nullptr);
 762   lock.notify_all(thread);
 763   // Ignore pending exception, since we are exiting anyway
 764   thread->clear_pending_exception();
 765 }
 766 
 767 static bool is_daemon(oop threadObj) {
 768   return (threadObj != nullptr && java_lang_Thread::is_daemon(threadObj));
 769 }
 770 
 771 // For any new cleanup additions, please check to see if they need to be applied to
 772 // cleanup_failed_attach_current_thread as well.
 773 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
 774   assert(this == JavaThread::current(), "thread consistency check");
 775   assert(!is_exiting(), "should not be exiting or terminated already");
 776 
 777   elapsedTimer _timer_exit_phase1;
 778   elapsedTimer _timer_exit_phase2;
 779   elapsedTimer _timer_exit_phase3;
 780   elapsedTimer _timer_exit_phase4;
 781 
 782   if (log_is_enabled(Debug, os, thread, timer)) {
 783     _timer_exit_phase1.start();
 784   }
 785 
 786   HandleMark hm(this);
 787   Handle uncaught_exception(this, this->pending_exception());
 788   this->clear_pending_exception();
 789   Handle threadObj(this, this->threadObj());
 790   assert(threadObj.not_null(), "Java thread object should be created");
 791 
 792   if (!destroy_vm) {
 793     if (uncaught_exception.not_null()) {
 794       EXCEPTION_MARK;
 795       // Call method Thread.dispatchUncaughtException().
 796       Klass* thread_klass = vmClasses::Thread_klass();
 797       JavaValue result(T_VOID);
 798       JavaCalls::call_virtual(&result,
 799                               threadObj, thread_klass,
 800                               vmSymbols::dispatchUncaughtException_name(),
 801                               vmSymbols::throwable_void_signature(),
 802                               uncaught_exception,
 803                               THREAD);
 804       if (HAS_PENDING_EXCEPTION) {
 805         ResourceMark rm(this);
 806         jio_fprintf(defaultStream::error_stream(),
 807                     "\nException: %s thrown from the UncaughtExceptionHandler"
 808                     " in thread \"%s\"\n",
 809                     pending_exception()->klass()->external_name(),
 810                     name());
 811         CLEAR_PENDING_EXCEPTION;
 812       }
 813     }
 814 
 815     if (!is_Compiler_thread()) {
 816       // We have finished executing user-defined Java code and now have to do the
 817       // implementation specific clean-up by calling Thread.exit(). We prevent any
 818       // asynchronous exceptions from being delivered while in Thread.exit()
 819       // to ensure the clean-up is not corrupted.
 820       NoAsyncExceptionDeliveryMark _no_async(this);
 821 
 822       EXCEPTION_MARK;
 823       JavaValue result(T_VOID);
 824       Klass* thread_klass = vmClasses::Thread_klass();
 825       JavaCalls::call_virtual(&result,
 826                               threadObj, thread_klass,
 827                               vmSymbols::exit_method_name(),
 828                               vmSymbols::void_method_signature(),
 829                               THREAD);
 830       CLEAR_PENDING_EXCEPTION;
 831     }
 832 
 833     // notify JVMTI
 834     if (JvmtiExport::should_post_thread_life()) {
 835       JvmtiExport::post_thread_end(this);
 836     }
 837   } else {
 838     // before_exit() has already posted JVMTI THREAD_END events
 839   }
 840 
 841   // Cleanup any pending async exception now since we cannot access oops after
 842   // BarrierSet::barrier_set()->on_thread_detach() has been executed.
 843   if (has_async_exception_condition()) {
 844     handshake_state()->clean_async_exception_operation();
 845   }
 846 
 847   // The careful dance between thread suspension and exit is handled here.
 848   // Since we are in thread_in_vm state and suspension is done with handshakes,
 849   // we can just put in the exiting state and it will be correctly handled.
 850   // Also, no more async exceptions will be added to the queue after this point.
 851   set_terminated(_thread_exiting);
 852   ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
 853 
 854   if (log_is_enabled(Debug, os, thread, timer)) {
 855     _timer_exit_phase1.stop();
 856     _timer_exit_phase2.start();
 857   }
 858 
 859   // Capture daemon status before the thread is marked as terminated.
 860   bool daemon = is_daemon(threadObj());
 861 
 862   // Notify waiters on thread object. This has to be done after exit() is called
 863   // on the thread (if the thread is the last thread in a daemon ThreadGroup the
 864   // group should have the destroyed bit set before waiters are notified).
 865   ensure_join(this);
 866   assert(!this->has_pending_exception(), "ensure_join should have cleared");
 867 
 868   if (log_is_enabled(Debug, os, thread, timer)) {
 869     _timer_exit_phase2.stop();
 870     _timer_exit_phase3.start();
 871   }
 872   // 6282335 JNI DetachCurrentThread spec states that all Java monitors
 873   // held by this thread must be released. The spec does not distinguish
 874   // between JNI-acquired and regular Java monitors. We can only see
 875   // regular Java monitors here if monitor enter-exit matching is broken.
 876   //
 877   // ensure_join() ignores IllegalThreadStateExceptions, and so does
 878   // ObjectSynchronizer::release_monitors_owned_by_thread().
 879   if (exit_type == jni_detach) {
 880     // Sanity check even though JNI DetachCurrentThread() would have
 881     // returned JNI_ERR if there was a Java frame. JavaThread exit
 882     // should be done executing Java code by the time we get here.
 883     assert(!this->has_last_Java_frame(),
 884            "should not have a Java frame when detaching or exiting");
 885     ObjectSynchronizer::release_monitors_owned_by_thread(this);
 886     assert(!this->has_pending_exception(), "release_monitors should have cleared");
 887   }
 888 
 889   // Since above code may not release JNI monitors and if someone forgot to do an
 890   // JNI monitorexit, held count should be equal jni count.
 891   // Consider scan all object monitor for this owner if JNI count > 0 (at least on detach).
 892   assert(held_monitor_count() == jni_monitor_count(),
 893          "held monitor count should be equal to jni: " INTX_FORMAT " != " INTX_FORMAT,
 894          held_monitor_count(), jni_monitor_count());
 895   if (CheckJNICalls && jni_monitor_count() > 0) {
 896     // We would like a fatal here, but due to we never checked this before there
 897     // is a lot of tests which breaks, even with an error log.
 898     log_debug(jni)("JavaThread %s (tid: " UINTX_FORMAT ") with Objects still locked by JNI MonitorEnter.",
 899       exit_type == JavaThread::normal_exit ? "exiting" : "detaching", os::current_thread_id());
 900   }
 901   assert(obj_locker_count() == 0, "expected 0 but found: " INTX_FORMAT, obj_locker_count());
 902 
 903   // These things needs to be done while we are still a Java Thread. Make sure that thread
 904   // is in a consistent state, in case GC happens
 905   JFR_ONLY(Jfr::on_thread_exit(this);)
 906 
 907   if (active_handles() != nullptr) {
 908     JNIHandleBlock* block = active_handles();
 909     set_active_handles(nullptr);
 910     JNIHandleBlock::release_block(block);
 911   }
 912 
 913   if (free_handle_block() != nullptr) {
 914     JNIHandleBlock* block = free_handle_block();
 915     set_free_handle_block(nullptr);
 916     JNIHandleBlock::release_block(block);
 917   }
 918 
 919   // These have to be removed while this is still a valid thread.
 920   _stack_overflow_state.remove_stack_guard_pages();
 921 
 922   if (UseTLAB) {
 923     tlab().retire();
 924   }
 925 
 926   if (JvmtiEnv::environments_might_exist()) {
 927     JvmtiExport::cleanup_thread(this);
 928   }
 929 
 930   // We need to cache the thread name for logging purposes below as once
 931   // we have called on_thread_detach this thread must not access any oops.
 932   char* thread_name = nullptr;
 933   if (log_is_enabled(Debug, os, thread, timer)) {
 934     ResourceMark rm(this);
 935     thread_name = os::strdup(name());
 936   }
 937 
 938   log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
 939     exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
 940     os::current_thread_id());
 941 
 942   if (log_is_enabled(Debug, os, thread, timer)) {
 943     _timer_exit_phase3.stop();
 944     _timer_exit_phase4.start();
 945   }
 946 
 947 #if INCLUDE_JVMCI
 948   if (JVMCICounterSize > 0) {
 949     if (jvmci_counters_include(this)) {
 950       for (int i = 0; i < JVMCICounterSize; i++) {
 951         _jvmci_old_thread_counters[i] += _jvmci_counters[i];
 952       }
 953     }
 954   }
 955 #endif // INCLUDE_JVMCI
 956 
 957   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread.
 958   // We call BarrierSet::barrier_set()->on_thread_detach() here so no touching of oops after this point.
 959   Threads::remove(this, daemon);
 960 
 961   if (log_is_enabled(Debug, os, thread, timer)) {
 962     _timer_exit_phase4.stop();
 963     log_debug(os, thread, timer)("name='%s'"
 964                                  ", exit-phase1=" JLONG_FORMAT
 965                                  ", exit-phase2=" JLONG_FORMAT
 966                                  ", exit-phase3=" JLONG_FORMAT
 967                                  ", exit-phase4=" JLONG_FORMAT,
 968                                  thread_name,
 969                                  _timer_exit_phase1.milliseconds(),
 970                                  _timer_exit_phase2.milliseconds(),
 971                                  _timer_exit_phase3.milliseconds(),
 972                                  _timer_exit_phase4.milliseconds());
 973     os::free(thread_name);
 974   }
 975 }
 976 
 977 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) {
 978   if (active_handles() != nullptr) {
 979     JNIHandleBlock* block = active_handles();
 980     set_active_handles(nullptr);
 981     JNIHandleBlock::release_block(block);
 982   }
 983 
 984   if (free_handle_block() != nullptr) {
 985     JNIHandleBlock* block = free_handle_block();
 986     set_free_handle_block(nullptr);
 987     JNIHandleBlock::release_block(block);
 988   }
 989 
 990   // These have to be removed while this is still a valid thread.
 991   _stack_overflow_state.remove_stack_guard_pages();
 992 
 993   if (UseTLAB) {
 994     tlab().retire();
 995   }
 996 
 997   Threads::remove(this, is_daemon);
 998   this->smr_delete();
 999 }
1000 
1001 JavaThread* JavaThread::active() {
1002   Thread* thread = Thread::current();
1003   if (thread->is_Java_thread()) {
1004     return JavaThread::cast(thread);
1005   } else {
1006     assert(thread->is_VM_thread(), "this must be a vm thread");
1007     VM_Operation* op = ((VMThread*) thread)->vm_operation();
1008     JavaThread *ret = op == nullptr ? nullptr : JavaThread::cast(op->calling_thread());
1009     return ret;
1010   }
1011 }
1012 
1013 bool JavaThread::is_lock_owned(address adr) const {
1014   assert(LockingMode != LM_LIGHTWEIGHT, "should not be called with new lightweight locking");
1015   if (Thread::is_lock_owned(adr)) return true;
1016 
1017   for (MonitorChunk* chunk = monitor_chunks(); chunk != nullptr; chunk = chunk->next()) {
1018     if (chunk->contains(adr)) return true;
1019   }
1020 
1021   return false;
1022 }
1023 
1024 oop JavaThread::exception_oop() const {
1025   return Atomic::load(&_exception_oop);
1026 }
1027 
1028 void JavaThread::set_exception_oop(oop o) {
1029   Atomic::store(&_exception_oop, o);
1030 }
1031 
1032 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
1033   chunk->set_next(monitor_chunks());
1034   set_monitor_chunks(chunk);
1035 }
1036 
1037 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
1038   guarantee(monitor_chunks() != nullptr, "must be non empty");
1039   if (monitor_chunks() == chunk) {
1040     set_monitor_chunks(chunk->next());
1041   } else {
1042     MonitorChunk* prev = monitor_chunks();
1043     while (prev->next() != chunk) prev = prev->next();
1044     prev->set_next(chunk->next());
1045   }
1046 }
1047 
1048 void JavaThread::handle_special_runtime_exit_condition() {
1049   if (is_obj_deopt_suspend()) {
1050     frame_anchor()->make_walkable();
1051     wait_for_object_deoptimization();
1052   }
1053   JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
1054 }
1055 
1056 
1057 // Asynchronous exceptions support
1058 //
1059 void JavaThread::handle_async_exception(oop java_throwable) {
1060   assert(java_throwable != nullptr, "should have an _async_exception to throw");
1061   assert(!is_at_poll_safepoint(), "should have never called this method");
1062 
1063   if (has_last_Java_frame()) {
1064     frame f = last_frame();
1065     if (f.is_runtime_frame()) {
1066       // If the topmost frame is a runtime stub, then we are calling into
1067       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
1068       // must deoptimize the caller before continuing, as the compiled exception
1069       // handler table may not be valid.
1070       RegisterMap reg_map(this,
1071                           RegisterMap::UpdateMap::skip,
1072                           RegisterMap::ProcessFrames::include,
1073                           RegisterMap::WalkContinuation::skip);
1074       frame compiled_frame = f.sender(&reg_map);
1075       if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
1076         Deoptimization::deoptimize(this, compiled_frame);
1077       }
1078     }
1079   }
1080 
1081   // We cannot call Exceptions::_throw(...) here because we cannot block
1082   set_pending_exception(java_throwable, __FILE__, __LINE__);
1083 
1084   clear_scopedValueBindings();
1085 
1086   LogTarget(Info, exceptions) lt;
1087   if (lt.is_enabled()) {
1088     ResourceMark rm;
1089     LogStream ls(lt);
1090     ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
1091     if (has_last_Java_frame()) {
1092       frame f = last_frame();
1093       ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
1094     }
1095     ls.print_cr(" of type: %s", java_throwable->klass()->external_name());
1096   }
1097 }
1098 
1099 void JavaThread::install_async_exception(AsyncExceptionHandshake* aeh) {
1100   // Do not throw asynchronous exceptions against the compiler thread
1101   // or if the thread is already exiting.
1102   if (!can_call_java() || is_exiting()) {
1103     delete aeh;
1104     return;
1105   }
1106 
1107   oop exception = aeh->exception();
1108   Handshake::execute(aeh, this);  // Install asynchronous handshake
1109 
1110   ResourceMark rm;
1111   if (log_is_enabled(Info, exceptions)) {
1112     log_info(exceptions)("Pending Async. exception installed of type: %s",
1113                          InstanceKlass::cast(exception->klass())->external_name());
1114   }
1115   // for AbortVMOnException flag
1116   Exceptions::debug_check_abort(exception->klass()->external_name());
1117 
1118   oop vt_oop = vthread();
1119   if (vt_oop == nullptr || !vt_oop->is_a(vmClasses::BaseVirtualThread_klass())) {
1120     // Interrupt thread so it will wake up from a potential wait()/sleep()/park()
1121     java_lang_Thread::set_interrupted(threadObj(), true);
1122     this->interrupt();
1123   }
1124 }
1125 
1126 class InstallAsyncExceptionHandshake : public HandshakeClosure {
1127   AsyncExceptionHandshake* _aeh;
1128 public:
1129   InstallAsyncExceptionHandshake(AsyncExceptionHandshake* aeh) :
1130     HandshakeClosure("InstallAsyncException"), _aeh(aeh) {}
1131   ~InstallAsyncExceptionHandshake() {
1132     // If InstallAsyncExceptionHandshake was never executed we need to clean up _aeh.
1133     delete _aeh;
1134   }
1135   void do_thread(Thread* thr) {
1136     JavaThread* target = JavaThread::cast(thr);
1137     target->install_async_exception(_aeh);
1138     _aeh = nullptr;
1139   }
1140 };
1141 
1142 void JavaThread::send_async_exception(JavaThread* target, oop java_throwable) {
1143   OopHandle e(Universe::vm_global(), java_throwable);
1144   InstallAsyncExceptionHandshake iaeh(new AsyncExceptionHandshake(e));
1145   Handshake::execute(&iaeh, target);
1146 }
1147 
1148 #if INCLUDE_JVMTI
1149 void JavaThread::set_is_in_VTMS_transition(bool val) {
1150   assert(is_in_VTMS_transition() != val, "already %s transition", val ? "inside" : "outside");
1151   _is_in_VTMS_transition = val;
1152 }
1153 
1154 #ifdef ASSERT
1155 void JavaThread::set_is_VTMS_transition_disabler(bool val) {
1156   _is_VTMS_transition_disabler = val;
1157 }
1158 #endif
1159 #endif
1160 
1161 // External suspension mechanism.
1162 //
1163 // Guarantees on return (for a valid target thread):
1164 //   - Target thread will not execute any new bytecode.
1165 //   - Target thread will not enter any new monitors.
1166 //
1167 bool JavaThread::java_suspend() {
1168 #if INCLUDE_JVMTI
1169   // Suspending a JavaThread in VTMS transition or disabling VTMS transitions can cause deadlocks.
1170   assert(!is_in_VTMS_transition(), "no suspend allowed in VTMS transition");
1171   assert(!is_VTMS_transition_disabler(), "no suspend allowed for VTMS transition disablers");
1172 #endif
1173 
1174   guarantee(Thread::is_JavaThread_protected(/* target */ this),
1175             "target JavaThread is not protected in calling context.");
1176   return this->handshake_state()->suspend();
1177 }
1178 
1179 bool JavaThread::java_resume() {
1180   guarantee(Thread::is_JavaThread_protected_by_TLH(/* target */ this),
1181             "missing ThreadsListHandle in calling context.");
1182   return this->handshake_state()->resume();
1183 }
1184 
1185 // Wait for another thread to perform object reallocation and relocking on behalf of
1186 // this thread. The current thread is required to change to _thread_blocked in order
1187 // to be seen to be safepoint/handshake safe whilst suspended and only after becoming
1188 // handshake safe, the other thread can complete the handshake used to synchronize
1189 // with this thread and then perform the reallocation and relocking.
1190 // See EscapeBarrier::sync_and_suspend_*()
1191 
1192 void JavaThread::wait_for_object_deoptimization() {
1193   assert(!has_last_Java_frame() || frame_anchor()->walkable(), "should have walkable stack");
1194   assert(this == Thread::current(), "invariant");
1195 
1196   bool spin_wait = os::is_MP();
1197   do {
1198     ThreadBlockInVM tbivm(this, true /* allow_suspend */);
1199     // Wait for object deoptimization if requested.
1200     if (spin_wait) {
1201       // A single deoptimization is typically very short. Microbenchmarks
1202       // showed 5% better performance when spinning.
1203       const uint spin_limit = 10 * SpinYield::default_spin_limit;
1204       SpinYield spin(spin_limit);
1205       for (uint i = 0; is_obj_deopt_suspend() && i < spin_limit; i++) {
1206         spin.wait();
1207       }
1208       // Spin just once
1209       spin_wait = false;
1210     } else {
1211       MonitorLocker ml(this, EscapeBarrier_lock, Monitor::_no_safepoint_check_flag);
1212       if (is_obj_deopt_suspend()) {
1213         ml.wait();
1214       }
1215     }
1216     // A handshake for obj. deoptimization suspend could have been processed so
1217     // we must check after processing.
1218   } while (is_obj_deopt_suspend());
1219 }
1220 
1221 #ifdef ASSERT
1222 // Verify the JavaThread has not yet been published in the Threads::list, and
1223 // hence doesn't need protection from concurrent access at this stage.
1224 void JavaThread::verify_not_published() {
1225   // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
1226   // since an unpublished JavaThread doesn't participate in the
1227   // Thread-SMR protocol for keeping a ThreadsList alive.
1228   assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
1229 }
1230 #endif
1231 
1232 // Slow path when the native==>Java barriers detect a safepoint/handshake is
1233 // pending, when _suspend_flags is non-zero or when we need to process a stack
1234 // watermark. Also check for pending async exceptions (except unsafe access error).
1235 // Note only the native==>Java barriers can call this function when thread state
1236 // is _thread_in_native_trans.
1237 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
1238   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
1239   assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "Unwalkable stack in native->Java transition");
1240 
1241   thread->set_thread_state(_thread_in_vm);
1242 
1243   // Enable WXWrite: called directly from interpreter native wrapper.
1244   MACOS_AARCH64_ONLY(ThreadWXEnable wx(WXWrite, thread));
1245 
1246   SafepointMechanism::process_if_requested_with_exit_check(thread, true /* check asyncs */);
1247 
1248   // After returning from native, it could be that the stack frames are not
1249   // yet safe to use. We catch such situations in the subsequent stack watermark
1250   // barrier, which will trap unsafe stack frames.
1251   StackWatermarkSet::before_unwind(thread);
1252 }
1253 
1254 #ifndef PRODUCT
1255 // Deoptimization
1256 // Function for testing deoptimization
1257 void JavaThread::deoptimize() {
1258   StackFrameStream fst(this, false /* update */, true /* process_frames */);
1259   bool deopt = false;           // Dump stack only if a deopt actually happens.
1260   bool only_at = strlen(DeoptimizeOnlyAt) > 0;
1261   // Iterate over all frames in the thread and deoptimize
1262   for (; !fst.is_done(); fst.next()) {
1263     if (fst.current()->can_be_deoptimized()) {
1264 
1265       if (only_at) {
1266         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt
1267         // consists of comma or carriage return separated numbers so
1268         // search for the current bci in that string.
1269         address pc = fst.current()->pc();
1270         nmethod* nm =  (nmethod*) fst.current()->cb();
1271         ScopeDesc* sd = nm->scope_desc_at(pc);
1272         char buffer[8];
1273         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
1274         size_t len = strlen(buffer);
1275         const char * found = strstr(DeoptimizeOnlyAt, buffer);
1276         while (found != nullptr) {
1277           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
1278               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
1279             // Check that the bci found is bracketed by terminators.
1280             break;
1281           }
1282           found = strstr(found + 1, buffer);
1283         }
1284         if (!found) {
1285           continue;
1286         }
1287       }
1288 
1289       if (DebugDeoptimization && !deopt) {
1290         deopt = true; // One-time only print before deopt
1291         tty->print_cr("[BEFORE Deoptimization]");
1292         trace_frames();
1293         trace_stack();
1294       }
1295       Deoptimization::deoptimize(this, *fst.current());
1296     }
1297   }
1298 
1299   if (DebugDeoptimization && deopt) {
1300     tty->print_cr("[AFTER Deoptimization]");
1301     trace_frames();
1302   }
1303 }
1304 
1305 
1306 // Make zombies
1307 void JavaThread::make_zombies() {
1308   for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
1309     if (fst.current()->can_be_deoptimized()) {
1310       // it is a Java nmethod
1311       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
1312       nm->make_not_entrant();
1313     }
1314   }
1315 }
1316 #endif // PRODUCT
1317 
1318 
1319 void JavaThread::deoptimize_marked_methods() {
1320   if (!has_last_Java_frame()) return;
1321   StackFrameStream fst(this, false /* update */, true /* process_frames */);
1322   for (; !fst.is_done(); fst.next()) {
1323     if (fst.current()->should_be_deoptimized()) {
1324       Deoptimization::deoptimize(this, *fst.current());
1325     }
1326   }
1327 }
1328 
1329 #ifdef ASSERT
1330 void JavaThread::verify_frame_info() {
1331   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
1332          (has_last_Java_frame() && java_call_counter() > 0),
1333          "unexpected frame info: has_last_frame=%s, java_call_counter=%d",
1334          has_last_Java_frame() ? "true" : "false", java_call_counter());
1335 }
1336 #endif
1337 
1338 // Push on a new block of JNI handles.
1339 void JavaThread::push_jni_handle_block() {
1340   // Allocate a new block for JNI handles.
1341   // Inlined code from jni_PushLocalFrame()
1342   JNIHandleBlock* old_handles = active_handles();
1343   JNIHandleBlock* new_handles = JNIHandleBlock::allocate_block(this);
1344   assert(old_handles != nullptr && new_handles != nullptr, "should not be null");
1345   new_handles->set_pop_frame_link(old_handles);  // make sure java handles get gc'd.
1346   set_active_handles(new_handles);
1347 }
1348 
1349 // Pop off the current block of JNI handles.
1350 void JavaThread::pop_jni_handle_block() {
1351   // Release our JNI handle block
1352   JNIHandleBlock* old_handles = active_handles();
1353   JNIHandleBlock* new_handles = old_handles->pop_frame_link();
1354   assert(new_handles != nullptr, "should never set active handles to null");
1355   set_active_handles(new_handles);
1356   old_handles->set_pop_frame_link(nullptr);
1357   JNIHandleBlock::release_block(old_handles, this);
1358 }
1359 
1360 void JavaThread::oops_do_no_frames(OopClosure* f, CodeBlobClosure* cf) {
1361   // Verify that the deferred card marks have been flushed.
1362   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
1363 
1364   // Traverse the GCHandles
1365   Thread::oops_do_no_frames(f, cf);
1366 
1367   if (active_handles() != nullptr) {
1368     active_handles()->oops_do(f);
1369   }
1370 
1371   DEBUG_ONLY(verify_frame_info();)
1372 
1373   if (has_last_Java_frame()) {
1374     // Traverse the monitor chunks
1375     for (MonitorChunk* chunk = monitor_chunks(); chunk != nullptr; chunk = chunk->next()) {
1376       chunk->oops_do(f);
1377     }
1378   }
1379 
1380   assert(vframe_array_head() == nullptr, "deopt in progress at a safepoint!");
1381   // If we have deferred set_locals there might be oops waiting to be
1382   // written
1383   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = JvmtiDeferredUpdates::deferred_locals(this);
1384   if (list != nullptr) {
1385     for (int i = 0; i < list->length(); i++) {
1386       list->at(i)->oops_do(f);
1387     }
1388   }
1389 
1390   // Traverse instance variables at the end since the GC may be moving things
1391   // around using this function
1392   f->do_oop((oop*) &_vm_result);
1393   f->do_oop((oop*) &_exception_oop);
1394 #if INCLUDE_JVMCI
1395   f->do_oop((oop*) &_jvmci_reserved_oop0);
1396 #endif
1397 
1398   if (jvmti_thread_state() != nullptr) {
1399     jvmti_thread_state()->oops_do(f, cf);
1400   }
1401 
1402   // The continuation oops are really on the stack. But there is typically at most
1403   // one of those per thread, so we handle them here in the oops_do_no_frames part
1404   // so that we don't have to sprinkle as many stack watermark checks where these
1405   // oops are used. We just need to make sure the thread has started processing.
1406   ContinuationEntry* entry = _cont_entry;
1407   while (entry != nullptr) {
1408     f->do_oop((oop*)entry->cont_addr());
1409     f->do_oop((oop*)entry->chunk_addr());
1410     entry = entry->parent();
1411   }
1412 
1413   if (LockingMode == LM_LIGHTWEIGHT) {
1414     lock_stack().oops_do(f);
1415   }
1416 }
1417 
1418 void JavaThread::oops_do_frames(OopClosure* f, CodeBlobClosure* cf) {
1419   if (!has_last_Java_frame()) {
1420     return;
1421   }
1422   // Finish any pending lazy GC activity for the frames
1423   StackWatermarkSet::finish_processing(this, nullptr /* context */, StackWatermarkKind::gc);
1424   // Traverse the execution stack
1425   for (StackFrameStream fst(this, true /* update */, false /* process_frames */); !fst.is_done(); fst.next()) {
1426     fst.current()->oops_do(f, cf, fst.register_map());
1427   }
1428 }
1429 
1430 #ifdef ASSERT
1431 void JavaThread::verify_states_for_handshake() {
1432   // This checks that the thread has a correct frame state during a handshake.
1433   verify_frame_info();
1434 }
1435 #endif
1436 
1437 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
1438   DEBUG_ONLY(verify_frame_info();)
1439   MACOS_AARCH64_ONLY(ThreadWXEnable wx(WXWrite, Thread::current());)
1440 
1441   if (has_last_Java_frame()) {
1442     // Traverse the execution stack
1443     for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
1444       fst.current()->nmethods_do(cf);
1445     }
1446   }
1447 
1448   if (jvmti_thread_state() != nullptr) {
1449     jvmti_thread_state()->nmethods_do(cf);
1450   }
1451 }
1452 
1453 void JavaThread::metadata_do(MetadataClosure* f) {
1454   if (has_last_Java_frame()) {
1455     // Traverse the execution stack to call f() on the methods in the stack
1456     for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
1457       fst.current()->metadata_do(f);
1458     }
1459   } else if (is_Compiler_thread()) {
1460     // need to walk ciMetadata in current compile tasks to keep alive.
1461     CompilerThread* ct = (CompilerThread*)this;
1462     if (ct->env() != nullptr) {
1463       ct->env()->metadata_do(f);
1464     }
1465     CompileTask* task = ct->task();
1466     if (task != nullptr) {
1467       task->metadata_do(f);
1468     }
1469   }
1470 }
1471 
1472 // Printing
1473 static const char* _get_thread_state_name(JavaThreadState _thread_state) {
1474   switch (_thread_state) {
1475   case _thread_uninitialized:     return "_thread_uninitialized";
1476   case _thread_new:               return "_thread_new";
1477   case _thread_new_trans:         return "_thread_new_trans";
1478   case _thread_in_native:         return "_thread_in_native";
1479   case _thread_in_native_trans:   return "_thread_in_native_trans";
1480   case _thread_in_vm:             return "_thread_in_vm";
1481   case _thread_in_vm_trans:       return "_thread_in_vm_trans";
1482   case _thread_in_Java:           return "_thread_in_Java";
1483   case _thread_in_Java_trans:     return "_thread_in_Java_trans";
1484   case _thread_blocked:           return "_thread_blocked";
1485   case _thread_blocked_trans:     return "_thread_blocked_trans";
1486   default:                        return "unknown thread state";
1487   }
1488 }
1489 
1490 void JavaThread::print_thread_state_on(outputStream *st) const {
1491   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));
1492 }
1493 
1494 // Called by Threads::print() for VM_PrintThreads operation
1495 void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
1496   st->print_raw("\"");
1497   st->print_raw(name());
1498   st->print_raw("\" ");
1499   oop thread_oop = threadObj();
1500   if (thread_oop != nullptr) {
1501     st->print("#" INT64_FORMAT " [%ld] ", (int64_t)java_lang_Thread::thread_id(thread_oop), (long) osthread()->thread_id());
1502     if (java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");
1503     st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
1504   }
1505   Thread::print_on(st, print_extended_info);
1506   // print guess for valid stack memory region (assume 4K pages); helps lock debugging
1507   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
1508   if (thread_oop != nullptr) {
1509     if (is_vthread_mounted()) {
1510       oop vt = vthread();
1511       assert(vt != nullptr, "");
1512       st->print_cr("   Carrying virtual thread #" INT64_FORMAT, (int64_t)java_lang_Thread::thread_id(vt));
1513     } else {
1514       st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
1515     }
1516   }
1517 #ifndef PRODUCT
1518   _safepoint_state->print_on(st);
1519 #endif // PRODUCT
1520   if (is_Compiler_thread()) {
1521     CompileTask *task = ((CompilerThread*)this)->task();
1522     if (task != nullptr) {
1523       st->print("   Compiling: ");
1524       task->print(st, nullptr, true, false);
1525     } else {
1526       st->print("   No compile task");
1527     }
1528     st->cr();
1529   }
1530 }
1531 
1532 void JavaThread::print() const { print_on(tty); }
1533 
1534 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
1535   st->print("%s", get_thread_name_string(buf, buflen));
1536 }
1537 
1538 // Called by fatal error handler. The difference between this and
1539 // JavaThread::print() is that we can't grab lock or allocate memory.
1540 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
1541   st->print("%s \"%s\"", type_name(), get_thread_name_string(buf, buflen));
1542   Thread* current = Thread::current_or_null_safe();
1543   assert(current != nullptr, "cannot be called by a detached thread");
1544   st->fill_to(60);
1545   if (!current->is_Java_thread() || JavaThread::cast(current)->is_oop_safe()) {
1546     // Only access threadObj() if current thread is not a JavaThread
1547     // or if it is a JavaThread that can safely access oops.
1548     oop thread_obj = threadObj();
1549     if (thread_obj != nullptr) {
1550       st->print(java_lang_Thread::is_daemon(thread_obj) ? " daemon" : "       ");
1551     }
1552   }
1553   st->print(" [");
1554   st->print("%s", _get_thread_state_name(_thread_state));
1555   if (osthread()) {
1556     st->print(", id=%d", osthread()->thread_id());
1557   }
1558   st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ") (" PROPERFMT ")",
1559             p2i(stack_end()), p2i(stack_base()),
1560             PROPERFMTARGS(stack_size()));
1561   st->print("]");
1562 
1563   ThreadsSMRSupport::print_info_on(this, st);
1564   return;
1565 }
1566 
1567 
1568 // Verification
1569 
1570 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
1571   // ignore if there is no stack
1572   if (!has_last_Java_frame()) return;
1573   // traverse the stack frames. Starts from top frame.
1574   for (StackFrameStream fst(this, true /* update_map */, true /* process_frames */, false /* walk_cont */); !fst.is_done(); fst.next()) {
1575     frame* fr = fst.current();
1576     f(fr, fst.register_map());
1577   }
1578 }
1579 
1580 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
1581 
1582 void JavaThread::verify() {
1583   // Verify oops in the thread.
1584   oops_do(&VerifyOopClosure::verify_oop, nullptr);
1585 
1586   // Verify the stack frames.
1587   frames_do(frame_verify);
1588 }
1589 
1590 // CR 6300358 (sub-CR 2137150)
1591 // Most callers of this method assume that it can't return null but a
1592 // thread may not have a name whilst it is in the process of attaching to
1593 // the VM - see CR 6412693, and there are places where a JavaThread can be
1594 // seen prior to having its threadObj set (e.g., JNI attaching threads and
1595 // if vm exit occurs during initialization). These cases can all be accounted
1596 // for such that this method never returns null.
1597 const char* JavaThread::name() const  {
1598   if (Thread::is_JavaThread_protected(/* target */ this)) {
1599     // The target JavaThread is protected so get_thread_name_string() is safe:
1600     return get_thread_name_string();
1601   }
1602 
1603   // The target JavaThread is not protected so we return the default:
1604   return Thread::name();
1605 }
1606 
1607 // Like name() but doesn't include the protection check. This must only be
1608 // called when it is known to be safe, even though the protection check can't tell
1609 // that e.g. when this thread is the init_thread() - see instanceKlass.cpp.
1610 const char* JavaThread::name_raw() const  {
1611   return get_thread_name_string();
1612 }
1613 
1614 // Returns a non-null representation of this thread's name, or a suitable
1615 // descriptive string if there is no set name.
1616 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
1617   const char* name_str;
1618 #ifdef ASSERT
1619   Thread* current = Thread::current_or_null_safe();
1620   assert(current != nullptr, "cannot be called by a detached thread");
1621   if (!current->is_Java_thread() || JavaThread::cast(current)->is_oop_safe()) {
1622     // Only access threadObj() if current thread is not a JavaThread
1623     // or if it is a JavaThread that can safely access oops.
1624 #endif
1625     oop thread_obj = threadObj();
1626     if (thread_obj != nullptr) {
1627       oop name = java_lang_Thread::name(thread_obj);
1628       if (name != nullptr) {
1629         if (buf == nullptr) {
1630           name_str = java_lang_String::as_utf8_string(name);
1631         } else {
1632           name_str = java_lang_String::as_utf8_string(name, buf, buflen);
1633         }
1634       } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
1635         name_str = "<no-name - thread is attaching>";
1636       } else {
1637         name_str = "<un-named>";
1638       }
1639     } else {
1640       name_str = Thread::name();
1641     }
1642 #ifdef ASSERT
1643   } else {
1644     // Current JavaThread has exited...
1645     if (current == this) {
1646       // ... and is asking about itself:
1647       name_str = "<no-name - current JavaThread has exited>";
1648     } else {
1649       // ... and it can't safely determine this JavaThread's name so
1650       // use the default thread name.
1651       name_str = Thread::name();
1652     }
1653   }
1654 #endif
1655   assert(name_str != nullptr, "unexpected null thread name");
1656   return name_str;
1657 }
1658 
1659 // Helper to extract the name from the thread oop for logging.
1660 const char* JavaThread::name_for(oop thread_obj) {
1661   assert(thread_obj != nullptr, "precondition");
1662   oop name = java_lang_Thread::name(thread_obj);
1663   const char* name_str;
1664   if (name != nullptr) {
1665     name_str = java_lang_String::as_utf8_string(name);
1666   } else {
1667     name_str = "<un-named>";
1668   }
1669   return name_str;
1670 }
1671 
1672 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
1673 
1674   assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
1675   assert(NoPriority <= prio && prio <= MaxPriority, "sanity check");
1676   // Link Java Thread object <-> C++ Thread
1677 
1678   // Get the C++ thread object (an oop) from the JNI handle (a jthread)
1679   // and put it into a new Handle.  The Handle "thread_oop" can then
1680   // be used to pass the C++ thread object to other methods.
1681 
1682   // Set the Java level thread object (jthread) field of the
1683   // new thread (a JavaThread *) to C++ thread object using the
1684   // "thread_oop" handle.
1685 
1686   // Set the thread field (a JavaThread *) of the
1687   // oop representing the java_lang_Thread to the new thread (a JavaThread *).
1688 
1689   Handle thread_oop(Thread::current(),
1690                     JNIHandles::resolve_non_null(jni_thread));
1691   assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
1692          "must be initialized");
1693   set_threadOopHandles(thread_oop());
1694   set_lock_id(java_lang_Thread::thread_id(thread_oop()));
1695 
1696   if (prio == NoPriority) {
1697     prio = java_lang_Thread::priority(thread_oop());
1698     assert(prio != NoPriority, "A valid priority should be present");
1699   }
1700 
1701   // Push the Java priority down to the native thread; needs Threads_lock
1702   Thread::set_priority(this, prio);
1703 
1704   // Add the new thread to the Threads list and set it in motion.
1705   // We must have threads lock in order to call Threads::add.
1706   // It is crucial that we do not block before the thread is
1707   // added to the Threads list for if a GC happens, then the java_thread oop
1708   // will not be visited by GC.
1709   Threads::add(this);
1710   // Publish the JavaThread* in java.lang.Thread after the JavaThread* is
1711   // on a ThreadsList. We don't want to wait for the release when the
1712   // Theads_lock is dropped somewhere in the caller since the JavaThread*
1713   // is already visible to JVM/TI via the ThreadsList.
1714   java_lang_Thread::release_set_thread(thread_oop(), this);
1715 }
1716 
1717 oop JavaThread::current_park_blocker() {
1718   // Support for JSR-166 locks
1719   oop thread_oop = threadObj();
1720   if (thread_oop != nullptr) {
1721     return java_lang_Thread::park_blocker(thread_oop);
1722   }
1723   return nullptr;
1724 }
1725 
1726 // Print current stack trace for checked JNI warnings and JNI fatal errors.
1727 // This is the external format, selecting the platform or vthread
1728 // as applicable, and allowing for a native-only stack.
1729 void JavaThread::print_jni_stack() {
1730   assert(this == JavaThread::current(), "Can't print stack of other threads");
1731   if (!has_last_Java_frame()) {
1732     ResourceMark rm(this);
1733     char* buf = NEW_RESOURCE_ARRAY_RETURN_NULL(char, O_BUFLEN);
1734     if (buf == nullptr) {
1735       tty->print_cr("Unable to print native stack - out of memory");
1736       return;
1737     }
1738     address lastpc = nullptr;
1739     if (os::platform_print_native_stack(tty, nullptr, buf, O_BUFLEN, lastpc)) {
1740       // We have printed the native stack in platform-specific code,
1741       // so nothing else to do in this case.
1742     } else {
1743       frame f = os::current_frame();
1744       VMError::print_native_stack(tty, f, this, true /*print_source_info */,
1745                                   -1 /* max stack */, buf, O_BUFLEN);
1746     }
1747   } else {
1748     print_active_stack_on(tty);
1749   }
1750 }
1751 
1752 void JavaThread::print_stack_on(outputStream* st) {
1753   if (!has_last_Java_frame()) return;
1754 
1755   Thread* current_thread = Thread::current();
1756   ResourceMark rm(current_thread);
1757   HandleMark hm(current_thread);
1758 
1759   RegisterMap reg_map(this,
1760                       RegisterMap::UpdateMap::include,
1761                       RegisterMap::ProcessFrames::include,
1762                       RegisterMap::WalkContinuation::skip);
1763   vframe* start_vf = platform_thread_last_java_vframe(&reg_map);
1764   int count = 0;
1765   for (vframe* f = start_vf; f != nullptr; f = f->sender()) {
1766     if (f->is_java_frame()) {
1767       javaVFrame* jvf = javaVFrame::cast(f);
1768       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
1769 
1770       // Print out lock information
1771       if (JavaMonitorsInStackTrace) {
1772         jvf->print_lock_info_on(st, count);
1773       }
1774     } else {
1775       // Ignore non-Java frames
1776     }
1777 
1778     // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
1779     count++;
1780     if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
1781   }
1782 }
1783 
1784 void JavaThread::print_vthread_stack_on(outputStream* st) {
1785   assert(is_vthread_mounted(), "Caller should have checked this");
1786   assert(has_last_Java_frame(), "must be");
1787 
1788   Thread* current_thread = Thread::current();
1789   ResourceMark rm(current_thread);
1790   HandleMark hm(current_thread);
1791 
1792   RegisterMap reg_map(this,
1793                       RegisterMap::UpdateMap::include,
1794                       RegisterMap::ProcessFrames::include,
1795                       RegisterMap::WalkContinuation::include);
1796   ContinuationEntry* cont_entry = last_continuation();
1797   vframe* start_vf = last_java_vframe(&reg_map);
1798   int count = 0;
1799   for (vframe* f = start_vf; f != nullptr; f = f->sender()) {
1800     // Watch for end of vthread stack
1801     if (Continuation::is_continuation_enterSpecial(f->fr())) {
1802       assert(cont_entry == Continuation::get_continuation_entry_for_entry_frame(this, f->fr()), "");
1803       if (cont_entry->is_virtual_thread()) {
1804         break;
1805       }
1806       cont_entry = cont_entry->parent();
1807     }
1808     if (f->is_java_frame()) {
1809       javaVFrame* jvf = javaVFrame::cast(f);
1810       java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
1811 
1812       // Print out lock information
1813       if (JavaMonitorsInStackTrace) {
1814         jvf->print_lock_info_on(st, count);
1815       }
1816     } else {
1817       // Ignore non-Java frames
1818     }
1819 
1820     // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
1821     count++;
1822     if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
1823   }
1824 }
1825 
1826 void JavaThread::print_active_stack_on(outputStream* st) {
1827   if (is_vthread_mounted()) {
1828     print_vthread_stack_on(st);
1829   } else {
1830     print_stack_on(st);
1831   }
1832 }
1833 
1834 #if INCLUDE_JVMTI
1835 // Rebind JVMTI thread state from carrier to virtual or from virtual to carrier.
1836 JvmtiThreadState* JavaThread::rebind_to_jvmti_thread_state_of(oop thread_oop) {
1837   set_jvmti_vthread(thread_oop);
1838 
1839   // unbind current JvmtiThreadState from JavaThread
1840   JvmtiThreadState::unbind_from(jvmti_thread_state(), this);
1841 
1842   // bind new JvmtiThreadState to JavaThread
1843   JvmtiThreadState::bind_to(java_lang_Thread::jvmti_thread_state(thread_oop), this);
1844 
1845   return jvmti_thread_state();
1846 }
1847 #endif
1848 
1849 // JVMTI PopFrame support
1850 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
1851   assert(_popframe_preserved_args == nullptr, "should not wipe out old PopFrame preserved arguments");
1852   if (in_bytes(size_in_bytes) != 0) {
1853     _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
1854     _popframe_preserved_args_size = in_bytes(size_in_bytes);
1855     Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
1856   }
1857 }
1858 
1859 void* JavaThread::popframe_preserved_args() {
1860   return _popframe_preserved_args;
1861 }
1862 
1863 ByteSize JavaThread::popframe_preserved_args_size() {
1864   return in_ByteSize(_popframe_preserved_args_size);
1865 }
1866 
1867 WordSize JavaThread::popframe_preserved_args_size_in_words() {
1868   int sz = in_bytes(popframe_preserved_args_size());
1869   assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
1870   return in_WordSize(sz / wordSize);
1871 }
1872 
1873 void JavaThread::popframe_free_preserved_args() {
1874   assert(_popframe_preserved_args != nullptr, "should not free PopFrame preserved arguments twice");
1875   FREE_C_HEAP_ARRAY(char, (char*)_popframe_preserved_args);
1876   _popframe_preserved_args = nullptr;
1877   _popframe_preserved_args_size = 0;
1878 }
1879 
1880 #ifndef PRODUCT
1881 
1882 void JavaThread::trace_frames() {
1883   tty->print_cr("[Describe stack]");
1884   int frame_no = 1;
1885   for (StackFrameStream fst(this, true /* update */, true /* process_frames */); !fst.is_done(); fst.next()) {
1886     tty->print("  %d. ", frame_no++);
1887     fst.current()->print_value_on(tty, this);
1888     tty->cr();
1889   }
1890 }
1891 
1892 class PrintAndVerifyOopClosure: public OopClosure {
1893  protected:
1894   template <class T> inline void do_oop_work(T* p) {
1895     oop obj = RawAccess<>::oop_load(p);
1896     if (obj == nullptr) return;
1897     tty->print(INTPTR_FORMAT ": ", p2i(p));
1898     if (oopDesc::is_oop_or_null(obj)) {
1899       if (obj->is_objArray()) {
1900         tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
1901       } else {
1902         obj->print();
1903       }
1904     } else {
1905       tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
1906     }
1907     tty->cr();
1908   }
1909  public:
1910   virtual void do_oop(oop* p) { do_oop_work(p); }
1911   virtual void do_oop(narrowOop* p)  { do_oop_work(p); }
1912 };
1913 
1914 #ifdef ASSERT
1915 // Print or validate the layout of stack frames
1916 void JavaThread::print_frame_layout(int depth, bool validate_only) {
1917   ResourceMark rm;
1918   PreserveExceptionMark pm(this);
1919   FrameValues values;
1920   int frame_no = 0;
1921   for (StackFrameStream fst(this, true, true, true); !fst.is_done(); fst.next()) {
1922     fst.current()->describe(values, ++frame_no, fst.register_map());
1923     if (depth == frame_no) break;
1924   }
1925   Continuation::describe(values);
1926   if (validate_only) {
1927     values.validate();
1928   } else {
1929     tty->print_cr("[Describe stack layout]");
1930     values.print(this);
1931   }
1932 }
1933 #endif
1934 
1935 void JavaThread::trace_stack_from(vframe* start_vf) {
1936   ResourceMark rm;
1937   int vframe_no = 1;
1938   for (vframe* f = start_vf; f; f = f->sender()) {
1939     if (f->is_java_frame()) {
1940       javaVFrame::cast(f)->print_activation(vframe_no++);
1941     } else {
1942       f->print();
1943     }
1944     if (vframe_no > StackPrintLimit) {
1945       tty->print_cr("...<more frames>...");
1946       return;
1947     }
1948   }
1949 }
1950 
1951 
1952 void JavaThread::trace_stack() {
1953   if (!has_last_Java_frame()) return;
1954   Thread* current_thread = Thread::current();
1955   ResourceMark rm(current_thread);
1956   HandleMark hm(current_thread);
1957   RegisterMap reg_map(this,
1958                       RegisterMap::UpdateMap::include,
1959                       RegisterMap::ProcessFrames::include,
1960                       RegisterMap::WalkContinuation::skip);
1961   trace_stack_from(last_java_vframe(&reg_map));
1962 }
1963 
1964 
1965 #endif // PRODUCT
1966 
1967 void JavaThread::inc_held_monitor_count(intx i, bool jni) {
1968 #ifdef SUPPORT_MONITOR_COUNT
1969   assert(_held_monitor_count + 1 >= 0, "Must always be greater than 0: " INTX_FORMAT, _held_monitor_count + 1);
1970   _held_monitor_count += i;
1971   if (jni) {
1972     assert(_jni_monitor_count >= 0, "Must always be greater than 0: " INTX_FORMAT, _jni_monitor_count);
1973     _jni_monitor_count += i;
1974   }
1975 #endif
1976 }
1977 
1978 void JavaThread::dec_held_monitor_count(intx i, bool jni) {
1979 #ifdef SUPPORT_MONITOR_COUNT
1980   _held_monitor_count -= i;
1981   assert(_held_monitor_count + 1 >= 0, "Must always be greater than 0: " INTX_FORMAT, _held_monitor_count + 1);
1982   if (jni) {
1983     _jni_monitor_count -= i;
1984     assert(_jni_monitor_count >= 0, "Must always be greater than 0: " INTX_FORMAT, _jni_monitor_count);
1985   }
1986 #endif
1987 }
1988 
1989 frame JavaThread::vthread_last_frame() {
1990   assert (is_vthread_mounted(), "Virtual thread not mounted");
1991   return last_frame();
1992 }
1993 
1994 frame JavaThread::carrier_last_frame(RegisterMap* reg_map) {
1995   const ContinuationEntry* entry = vthread_continuation();
1996   guarantee (entry != nullptr, "Not a carrier thread");
1997   frame f = entry->to_frame();
1998   if (reg_map->process_frames()) {
1999     entry->flush_stack_processing(this);
2000   }
2001   entry->update_register_map(reg_map);
2002   return f.sender(reg_map);
2003 }
2004 
2005 frame JavaThread::platform_thread_last_frame(RegisterMap* reg_map) {
2006   return is_vthread_mounted() ? carrier_last_frame(reg_map) : last_frame();
2007 }
2008 
2009 javaVFrame* JavaThread::last_java_vframe(const frame f, RegisterMap *reg_map) {
2010   assert(reg_map != nullptr, "a map must be given");
2011   for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
2012     if (vf->is_java_frame()) return javaVFrame::cast(vf);
2013   }
2014   return nullptr;
2015 }
2016 
2017 Klass* JavaThread::security_get_caller_class(int depth) {
2018   ResetNoHandleMark rnhm;
2019   HandleMark hm(Thread::current());
2020 
2021   vframeStream vfst(this);
2022   vfst.security_get_caller_frame(depth);
2023   if (!vfst.at_end()) {
2024     return vfst.method()->method_holder();
2025   }
2026   return nullptr;
2027 }
2028 
2029 // Internal convenience function for millisecond resolution sleeps.
2030 bool JavaThread::sleep(jlong millis) {
2031   jlong nanos;
2032   if (millis > max_jlong / NANOUNITS_PER_MILLIUNIT) {
2033     // Conversion to nanos would overflow, saturate at max
2034     nanos = max_jlong;
2035   } else {
2036     nanos = millis * NANOUNITS_PER_MILLIUNIT;
2037   }
2038   return sleep_nanos(nanos);
2039 }
2040 
2041 // java.lang.Thread.sleep support
2042 // Returns true if sleep time elapsed as expected, and false
2043 // if the thread was interrupted.
2044 bool JavaThread::sleep_nanos(jlong nanos) {
2045   assert(this == Thread::current(),  "thread consistency check");
2046   assert(nanos >= 0, "nanos are in range");
2047 
2048   ParkEvent * const slp = this->_SleepEvent;
2049   // Because there can be races with thread interruption sending an unpark()
2050   // to the event, we explicitly reset it here to avoid an immediate return.
2051   // The actual interrupt state will be checked before we park().
2052   slp->reset();
2053   // Thread interruption establishes a happens-before ordering in the
2054   // Java Memory Model, so we need to ensure we synchronize with the
2055   // interrupt state.
2056   OrderAccess::fence();
2057 
2058   jlong prevtime = os::javaTimeNanos();
2059 
2060   jlong nanos_remaining = nanos;
2061 
2062   for (;;) {
2063     // interruption has precedence over timing out
2064     if (this->is_interrupted(true)) {
2065       return false;
2066     }
2067 
2068     if (nanos_remaining <= 0) {
2069       return true;
2070     }
2071 
2072     {
2073       ThreadBlockInVM tbivm(this);
2074       OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
2075       slp->park_nanos(nanos_remaining);
2076     }
2077 
2078     // Update elapsed time tracking
2079     jlong newtime = os::javaTimeNanos();
2080     if (newtime - prevtime < 0) {
2081       // time moving backwards, should only happen if no monotonic clock
2082       // not a guarantee() because JVM should not abort on kernel/glibc bugs
2083       assert(false,
2084              "unexpected time moving backwards detected in JavaThread::sleep()");
2085     } else {
2086       nanos_remaining -= (newtime - prevtime);
2087     }
2088     prevtime = newtime;
2089   }
2090 }
2091 
2092 // Last thread running calls java.lang.Shutdown.shutdown()
2093 void JavaThread::invoke_shutdown_hooks() {
2094   HandleMark hm(this);
2095 
2096   // We could get here with a pending exception, if so clear it now.
2097   if (this->has_pending_exception()) {
2098     this->clear_pending_exception();
2099   }
2100 
2101   EXCEPTION_MARK;
2102   Klass* shutdown_klass =
2103     SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
2104                                       THREAD);
2105   if (shutdown_klass != nullptr) {
2106     // SystemDictionary::resolve_or_null will return null if there was
2107     // an exception.  If we cannot load the Shutdown class, just don't
2108     // call Shutdown.shutdown() at all.  This will mean the shutdown hooks
2109     // won't be run.  Note that if a shutdown hook was registered,
2110     // the Shutdown class would have already been loaded
2111     // (Runtime.addShutdownHook will load it).
2112     JavaValue result(T_VOID);
2113     JavaCalls::call_static(&result,
2114                            shutdown_klass,
2115                            vmSymbols::shutdown_name(),
2116                            vmSymbols::void_method_signature(),
2117                            THREAD);
2118   }
2119   CLEAR_PENDING_EXCEPTION;
2120 }
2121 
2122 #ifndef PRODUCT
2123 void JavaThread::verify_cross_modify_fence_failure(JavaThread *thread) {
2124    report_vm_error(__FILE__, __LINE__, "Cross modify fence failure", "%p", thread);
2125 }
2126 #endif
2127 
2128 // Helper function to create the java.lang.Thread object for a
2129 // VM-internal thread. The thread will have the given name, and be
2130 // a member of the "system" ThreadGroup.
2131 Handle JavaThread::create_system_thread_object(const char* name, TRAPS) {
2132   Handle string = java_lang_String::create_from_str(name, CHECK_NH);
2133 
2134   // Initialize thread_oop to put it into the system threadGroup.
2135   // This is done by calling the Thread(ThreadGroup group, String name) constructor.
2136   Handle thread_group(THREAD, Universe::system_thread_group());
2137   Handle thread_oop =
2138     JavaCalls::construct_new_instance(vmClasses::Thread_klass(),
2139                                       vmSymbols::threadgroup_string_void_signature(),
2140                                       thread_group,
2141                                       string,
2142                                       CHECK_NH);
2143 
2144   return thread_oop;
2145 }
2146 
2147 // Starts the target JavaThread as a daemon of the given priority, and
2148 // bound to the given java.lang.Thread instance.
2149 // The Threads_lock is held for the duration.
2150 void JavaThread::start_internal_daemon(JavaThread* current, JavaThread* target,
2151                                        Handle thread_oop, ThreadPriority prio) {
2152 
2153   assert(target->osthread() != nullptr, "target thread is not properly initialized");
2154 
2155   MutexLocker mu(current, Threads_lock);
2156 
2157   // Initialize the fields of the thread_oop first.
2158   if (prio != NoPriority) {
2159     java_lang_Thread::set_priority(thread_oop(), prio);
2160     // Note: we don't call os::set_priority here. Possibly we should,
2161     // else all threads should call it themselves when they first run.
2162   }
2163 
2164   java_lang_Thread::set_daemon(thread_oop());
2165 
2166   // Now bind the thread_oop to the target JavaThread.
2167   target->set_threadOopHandles(thread_oop());
2168   target->set_lock_id(java_lang_Thread::thread_id(thread_oop()));
2169 
2170   Threads::add(target); // target is now visible for safepoint/handshake
2171   // Publish the JavaThread* in java.lang.Thread after the JavaThread* is
2172   // on a ThreadsList. We don't want to wait for the release when the
2173   // Theads_lock is dropped when the 'mu' destructor is run since the
2174   // JavaThread* is already visible to JVM/TI via the ThreadsList.
2175 
2176   assert(java_lang_Thread::thread(thread_oop()) == nullptr, "must not be alive");
2177   java_lang_Thread::release_set_thread(thread_oop(), target); // isAlive == true now
2178   Thread::start(target);
2179 }
2180 
2181 void JavaThread::vm_exit_on_osthread_failure(JavaThread* thread) {
2182   // At this point it may be possible that no osthread was created for the
2183   // JavaThread due to lack of resources. However, since this must work
2184   // for critical system threads just check and abort if this fails.
2185   if (thread->osthread() == nullptr) {
2186     // This isn't really an OOM condition, but historically this is what
2187     // we report.
2188     vm_exit_during_initialization("java.lang.OutOfMemoryError",
2189                                   os::native_thread_creation_failed_msg());
2190   }
2191 }
2192 
2193 void JavaThread::pretouch_stack() {
2194   // Given an established java thread stack with usable area followed by
2195   // shadow zone and reserved/yellow/red zone, pretouch the usable area ranging
2196   // from the current frame down to the start of the shadow zone.
2197   const address end = _stack_overflow_state.shadow_zone_safe_limit();
2198   if (is_in_full_stack(end)) {
2199     char* p1 = (char*) alloca(1);
2200     address here = (address) &p1;
2201     if (is_in_full_stack(here) && here > end) {
2202       size_t to_alloc = here - end;
2203       char* p2 = (char*) alloca(to_alloc);
2204       log_trace(os, thread)("Pretouching thread stack from " PTR_FORMAT " to " PTR_FORMAT ".",
2205                             p2i(p2), p2i(end));
2206       os::pretouch_memory(p2, p2 + to_alloc,
2207                           NOT_AIX(os::vm_page_size()) AIX_ONLY(4096));
2208     }
2209   }
2210 }
2211 
2212 // Deferred OopHandle release support.
2213 
2214 class OopHandleList : public CHeapObj<mtInternal> {
2215   static const int _count = 4;
2216   OopHandle _handles[_count];
2217   OopHandleList* _next;
2218   int _index;
2219  public:
2220   OopHandleList(OopHandleList* next) : _next(next), _index(0) {}
2221   void add(OopHandle h) {
2222     assert(_index < _count, "too many additions");
2223     _handles[_index++] = h;
2224   }
2225   ~OopHandleList() {
2226     assert(_index == _count, "usage error");
2227     for (int i = 0; i < _index; i++) {
2228       _handles[i].release(JavaThread::thread_oop_storage());
2229     }
2230   }
2231   OopHandleList* next() const { return _next; }
2232 };
2233 
2234 OopHandleList* JavaThread::_oop_handle_list = nullptr;
2235 
2236 // Called by the ServiceThread to do the work of releasing
2237 // the OopHandles.
2238 void JavaThread::release_oop_handles() {
2239   OopHandleList* list;
2240   {
2241     MutexLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
2242     list = _oop_handle_list;
2243     _oop_handle_list = nullptr;
2244   }
2245   assert(!SafepointSynchronize::is_at_safepoint(), "cannot be called at a safepoint");
2246 
2247   while (list != nullptr) {
2248     OopHandleList* l = list;
2249     list = l->next();
2250     delete l;
2251   }
2252 }
2253 
2254 // Add our OopHandles for later release.
2255 void JavaThread::add_oop_handles_for_release() {
2256   MutexLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
2257   OopHandleList* new_head = new OopHandleList(_oop_handle_list);
2258   new_head->add(_threadObj);
2259   new_head->add(_vthread);
2260   new_head->add(_jvmti_vthread);
2261   new_head->add(_scopedValueCache);
2262   _oop_handle_list = new_head;
2263   Service_lock->notify_all();
2264 }