Quelle  jvmtiExport.cpp   Sprache: C

/*
 * Copyright (c) 2003, 2022, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

#include "precompiled.hpp"
#include "classfile/javaClasses.inline.hpp"
#include "classfile/moduleEntry.hpp"
#include "classfile/vmClasses.hpp"
#include "classfile/vmSymbols.hpp"
#include "code/nmethod.hpp"
#include "code/pcDesc.hpp"
#include "code/scopeDesc.hpp"
#include "gc/shared/oopStorageSet.hpp"
#include "interpreter/interpreter.hpp"
#include "jvmtifiles/jvmtiEnv.hpp"
#include "logging/log.hpp"
#include "logging/logStream.hpp"
#include "memory/allocation.inline.hpp"
#include "memory/resourceArea.hpp"
#include "memory/universe.hpp"
#include "oops/klass.inline.hpp"
#include "oops/objArrayKlass.hpp"
#include "oops/objArrayOop.hpp"
#include "oops/oop.inline.hpp"
#include "oops/oopHandle.inline.hpp"
#include "prims/jvmtiCodeBlobEvents.hpp"
#include "prims/jvmtiEventController.hpp"
#include "prims/jvmtiEventController.inline.hpp"
#include "prims/jvmtiExport.hpp"
#include "prims/jvmtiImpl.hpp"
#include "prims/jvmtiManageCapabilities.hpp"
#include "prims/jvmtiRawMonitor.hpp"
#include "prims/jvmtiRedefineClasses.hpp"
#include "prims/jvmtiTagMap.hpp"
#include "prims/jvmtiThreadState.inline.hpp"
#include "runtime/arguments.hpp"
#include "runtime/fieldDescriptor.inline.hpp"
#include "runtime/handles.inline.hpp"
#include "runtime/interfaceSupport.inline.hpp"
#include "runtime/javaCalls.hpp"
#include "runtime/javaThread.hpp"
#include "runtime/jniHandles.inline.hpp"
#include "runtime/keepStackGCProcessed.hpp"
#include "runtime/objectMonitor.hpp"
#include "runtime/objectMonitor.inline.hpp"
#include "runtime/os.hpp"
#include "runtime/osThread.hpp"
#include "runtime/safepointVerifiers.hpp"
#include "runtime/serviceThread.hpp"
#include "runtime/threads.hpp"
#include "runtime/threadSMR.hpp"
#include "runtime/vframe.inline.hpp"
#include "runtime/vm_version.hpp"
#include "utilities/macros.hpp"

#ifdef JVMTI_TRACE
#define EVT_TRACE(evt,out) if ((JvmtiTrace::event_trace_flags(evt) & JvmtiTrace::SHOW_EVENT_SENT) != 0) { SafeResourceMark rm; log_trace(jvmti) out; }
#define EVT_TRIG_TRACE(evt,out) if ((JvmtiTrace::event_trace_flags(evt) & JvmtiTrace::SHOW_EVENT_TRIGGER) != 0) { SafeResourceMark rm; log_trace(jvmti) out; }
#else
#define EVT_TRIG_TRACE(evt,out)
#define EVT_TRACE(evt,out)
#endif

///////////////////////////////////////////////////////////////
//
// JvmtiEventTransition
//
// TO DO --
//  more handle purging

// Use this for JavaThreads and state is  _thread_in_vm.
class JvmtiJavaThreadEventTransition : StackObj {
private:
  ResourceMark _rm;
  ThreadToNativeFromVM _transition;
  HandleMark _hm;

public:
  JvmtiJavaThreadEventTransition(JavaThread *thread) :
    _rm(),
    _transition(thread),
    _hm(thread)  {};
};

// For JavaThreads which are not in _thread_in_vm state
// and other system threads use this.
class JvmtiThreadEventTransition : StackObj {
private:
  ResourceMark _rm;
  HandleMark _hm;
  JavaThreadState _saved_state;
  JavaThread *_jthread;

public:
  JvmtiThreadEventTransition(Thread *thread) : _rm(), _hm(thread) {
    if (thread->is_Java_thread()) {
       _jthread = JavaThread::cast(thread);
       _saved_state = _jthread->thread_state();
       if (_saved_state == _thread_in_Java) {
         ThreadStateTransition::transition_from_java(_jthread, _thread_in_native);
       } else {
         ThreadStateTransition::transition_from_vm(_jthread, _thread_in_native);
       }
    } else {
      _jthread = NULL;
    }
  }

  ~JvmtiThreadEventTransition() {
    if (_jthread != NULL)
      ThreadStateTransition::transition_from_native(_jthread, _saved_state);
  }
};


///////////////////////////////////////////////////////////////
//
// JvmtiEventMark
//

class JvmtiEventMark : public StackObj {
private:
  JavaThread *_thread;
  JNIEnv* _jni_env;
  JvmtiThreadState::ExceptionState _saved_exception_state;

public:
  JvmtiEventMark(JavaThread *thread) :  _thread(thread),
                                        _jni_env(thread->jni_environment()),
                                        _saved_exception_state(JvmtiThreadState::ES_CLEARED) {
    JvmtiThreadState *state = thread->jvmti_thread_state();
    // we are before an event.
    // Save current jvmti thread exception state.
    if (state != NULL) {
      _saved_exception_state = state->get_exception_state();
    }

    thread->push_jni_handle_block();
    assert(thread == JavaThread::current(), "thread must be current!");
    thread->frame_anchor()->make_walkable();
  };

  ~JvmtiEventMark() {
    _thread->pop_jni_handle_block();

    JvmtiThreadState* state = _thread->jvmti_thread_state();
    // we are continuing after an event.
    if (state != NULL) {
      // Restore the jvmti thread exception state.
      state->restore_exception_state(_saved_exception_state);
    }
  }

  jobject to_jobject(oop obj) { return JNIHandles::make_local(_thread,obj); }

  jclass to_jclass(Klass* klass) { return (klass == NULL ? NULL : (jclass)to_jobject(klass->java_mirror())); }

  jmethodID to_jmethodID(const methodHandle& method) { return method->jmethod_id(); }

  JNIEnv* jni_env() { return _jni_env; }
};

class JvmtiThreadEventMark : public JvmtiEventMark {
private:
  jobject _jthread;

public:
  JvmtiThreadEventMark(JavaThread *thread) :
    JvmtiEventMark(thread) {
    _jthread = to_jobject(thread->threadObj());
  };
 jthread jni_thread() { return (jthread)_jthread; }
};

class JvmtiVirtualThreadEventMark : public JvmtiEventMark {
private:
  jobject _jthread;

public:
  JvmtiVirtualThreadEventMark(JavaThread *thread) :
    JvmtiEventMark(thread) {
    assert(thread->vthread() != NULL || thread->threadObj() == NULL, "sanity check");
    _jthread = to_jobject(thread->vthread());
  };
  jthread jni_thread() { return (jthread)_jthread; }
};

class JvmtiClassEventMark : public JvmtiVirtualThreadEventMark {
private:
  jclass _jc;

public:
  JvmtiClassEventMark(JavaThread *thread, Klass* klass) :
    JvmtiVirtualThreadEventMark(thread) {
    _jc = to_jclass(klass);
  };
  jclass jni_class() { return _jc; }
};

class JvmtiMethodEventMark : public JvmtiVirtualThreadEventMark {
private:
  jmethodID _mid;

public:
  JvmtiMethodEventMark(JavaThread *thread, const methodHandle& method) :
    JvmtiVirtualThreadEventMark(thread),
    _mid(to_jmethodID(method)) {};
  jmethodID jni_methodID() { return _mid; }
};

class JvmtiLocationEventMark : public JvmtiMethodEventMark {
private:
  jlocation _loc;

public:
  JvmtiLocationEventMark(JavaThread *thread, const methodHandle& method, address location) :
    JvmtiMethodEventMark(thread, method),
    _loc(location - method->code_base()) {};
  jlocation location() { return _loc; }
};

class JvmtiExceptionEventMark : public JvmtiLocationEventMark {
private:
  jobject _exc;

public:
  JvmtiExceptionEventMark(JavaThread *thread, const methodHandle& method, address location, Handle exception) :
    JvmtiLocationEventMark(thread, method, location),
    _exc(to_jobject(exception())) {};
  jobject exception() { return _exc; }
};

class JvmtiClassFileLoadEventMark : public JvmtiThreadEventMark {
private:
  const char *_class_name;
  jobject _jloader;
  jobject _protection_domain;
  jclass  _class_being_redefined;

public:
  JvmtiClassFileLoadEventMark(JavaThread *thread, Symbol* name,
     Handle class_loader, Handle prot_domain, Klass* class_being_redefined) : JvmtiThreadEventMark(thread) {
      _class_name = name != NULL? name->as_utf8() : NULL;
      _jloader = (jobject)to_jobject(class_loader());
      _protection_domain = (jobject)to_jobject(prot_domain());
      if (class_being_redefined == NULL) {
        _class_being_redefined = NULL;
      } else {
        _class_being_redefined = (jclass)to_jclass(class_being_redefined);
      }
  };
  const char *class_name() {
    return _class_name;
  }
  jobject jloader() {
    return _jloader;
  }
  jobject protection_domain() {
    return _protection_domain;
  }
  jclass class_being_redefined() {
    return _class_being_redefined;
  }
};

//////////////////////////////////////////////////////////////////////////////

int               JvmtiExport::_field_access_count                        = 0;
int               JvmtiExport::_field_modification_count                  = 0;

bool              JvmtiExport::_can_access_local_variables                = false;
bool              JvmtiExport::_can_hotswap_or_post_breakpoint            = false;
bool              JvmtiExport::_can_modify_any_class                      = false;
bool              JvmtiExport::_can_walk_any_space                        = false;

uint64_t          JvmtiExport::_redefinition_count                        = 0;
bool              JvmtiExport::_all_dependencies_are_recorded             = false;

//
// field access management
//

// interpreter generator needs the address of the counter
address JvmtiExport::get_field_access_count_addr() {
  // We don't grab a lock because we don't want to
  // serialize field access between all threads. This means that a
  // thread on another processor can see the wrong count value and
  // may either miss making a needed call into post_field_access()
  // or will make an unneeded call into post_field_access(). We pay
  // this price to avoid slowing down the VM when we aren't watching
  // field accesses.
  // Other access/mutation safe by virtue of being in VM state.
  return (address)(&_field_access_count);
}

//
// field modification management
//

// interpreter generator needs the address of the counter
address JvmtiExport::get_field_modification_count_addr() {
  // We don't grab a lock because we don't
  // want to serialize field modification between all threads. This
  // means that a thread on another processor can see the wrong
  // count value and may either miss making a needed call into
  // post_field_modification() or will make an unneeded call into
  // post_field_modification(). We pay this price to avoid slowing
  // down the VM when we aren't watching field modifications.
  // Other access/mutation safe by virtue of being in VM state.
  return (address)(&_field_modification_count);
}


///////////////////////////////////////////////////////////////
// Functions needed by java.lang.instrument for starting up javaagent.
///////////////////////////////////////////////////////////////

jint
JvmtiExport::get_jvmti_interface(JavaVM *jvm, void **penv, jint version) {
  // The JVMTI_VERSION_INTERFACE_JVMTI part of the version number
  // has already been validated in JNI GetEnv().
  int major, minor, micro;

  // micro version doesn't matter here (yet?)
  decode_version_values(version, &major, &minor, µ);
  switch (major) {
    case 1:
      switch (minor) {
        case 0:  // version 1.0.<micro> is recognized
        case 1:  // version 1.1.<micro> is recognized
        case 2:  // version 1.2.<micro> is recognized
          break;

        default:
          return JNI_EVERSION;  // unsupported minor version number
      }
      break;
    case 9:
      switch (minor) {
        case 0:  // version 9.0.<micro> is recognized
          break;
        default:
          return JNI_EVERSION;  // unsupported minor version number
      }
      break;
    case 11:
      switch (minor) {
        case 0:  // version 11.0.<micro> is recognized
          break;
        default:
          return JNI_EVERSION;  // unsupported minor version number
      }
      break;
    default:
      // Starting from 13 we do not care about minor version anymore
      if (major < 13 || major > VM_Version::vm_major_version()) {
        return JNI_EVERSION;  // unsupported major version number
      }
  }
  if (Continuations::enabled()) {
    // Virtual threads support. There is a performance impact when VTMS transitions are enabled.
    java_lang_VirtualThread::set_notify_jvmti_events(true);
    if (JvmtiEnv::get_phase() == JVMTI_PHASE_LIVE) {
      ThreadInVMfromNative __tiv(JavaThread::current());
      java_lang_VirtualThread::init_static_notify_jvmti_events();
    }
  }

  if (JvmtiEnv::get_phase() == JVMTI_PHASE_LIVE) {
    JavaThread* current_thread = JavaThread::current();
    // transition code: native to VM
    ThreadInVMfromNative __tiv(current_thread);
    VM_ENTRY_BASE(jvmtiEnv*, JvmtiExport::get_jvmti_interface, current_thread)
    debug_only(VMNativeEntryWrapper __vew;)

    JvmtiEnv *jvmti_env = JvmtiEnv::create_a_jvmti(version);
    *penv = jvmti_env->jvmti_external();  // actual type is jvmtiEnv* -- not to be confused with JvmtiEnv*
    return JNI_OK;

  } else if (JvmtiEnv::get_phase() == JVMTI_PHASE_ONLOAD) {
    // not live, no thread to transition
    JvmtiEnv *jvmti_env = JvmtiEnv::create_a_jvmti(version);
    *penv = jvmti_env->jvmti_external();  // actual type is jvmtiEnv* -- not to be confused with JvmtiEnv*
    return JNI_OK;

  } else {
    // Called at the wrong time
    *penv = NULL;
    return JNI_EDETACHED;
  }
}

void
JvmtiExport::add_default_read_edges(Handle h_module, TRAPS) {
  if (!Universe::is_module_initialized()) {
    return; // extra safety
  }
  assert(!h_module.is_null(), "module should always be set");

  // Invoke the transformedByAgent method
  JavaValue result(T_VOID);
  JavaCalls::call_static(&result,
                         vmClasses::module_Modules_klass(),
                         vmSymbols::transformedByAgent_name(),
                         vmSymbols::transformedByAgent_signature(),
                         h_module,
                         THREAD);

  if (HAS_PENDING_EXCEPTION) {
    LogTarget(Trace, jvmti) log;
    LogStream log_stream(log);
    java_lang_Throwable::print(PENDING_EXCEPTION, &log_stream);
    log_stream.cr();
    CLEAR_PENDING_EXCEPTION;
    return;
  }
}

jvmtiError
JvmtiExport::add_module_reads(Handle module, Handle to_module, TRAPS) {
  if (!Universe::is_module_initialized()) {
    return JVMTI_ERROR_NONE; // extra safety
  }
  assert(!module.is_null(), "module should always be set");
  assert(!to_module.is_null(), "to_module should always be set");

  // Invoke the addReads method
  JavaValue result(T_VOID);
  JavaCalls::call_static(&result,
                         vmClasses::module_Modules_klass(),
                         vmSymbols::addReads_name(),
                         vmSymbols::addReads_signature(),
                         module,
                         to_module,
                         THREAD);

  if (HAS_PENDING_EXCEPTION) {
    LogTarget(Trace, jvmti) log;
    LogStream log_stream(log);
    java_lang_Throwable::print(PENDING_EXCEPTION, &log_stream);
    log_stream.cr();
    CLEAR_PENDING_EXCEPTION;
    return JVMTI_ERROR_INTERNAL;
  }
  return JVMTI_ERROR_NONE;
}

jvmtiError
JvmtiExport::add_module_exports(Handle module, Handle pkg_name, Handle to_module, TRAPS) {
  if (!Universe::is_module_initialized()) {
    return JVMTI_ERROR_NONE; // extra safety
  }
  assert(!module.is_null(), "module should always be set");
  assert(!to_module.is_null(), "to_module should always be set");
  assert(!pkg_name.is_null(), "pkg_name should always be set");

  // Invoke the addExports method
  JavaValue result(T_VOID);
  JavaCalls::call_static(&result,
                         vmClasses::module_Modules_klass(),
                         vmSymbols::addExports_name(),
                         vmSymbols::addExports_signature(),
                         module,
                         pkg_name,
                         to_module,
                         THREAD);

  if (HAS_PENDING_EXCEPTION) {
    Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
    LogTarget(Trace, jvmti) log;
    LogStream log_stream(log);
    java_lang_Throwable::print(PENDING_EXCEPTION, &log_stream);
    log_stream.cr();
    CLEAR_PENDING_EXCEPTION;
    if (ex_name == vmSymbols::java_lang_IllegalArgumentException()) {
      return JVMTI_ERROR_ILLEGAL_ARGUMENT;
    }
    return JVMTI_ERROR_INTERNAL;
  }
  return JVMTI_ERROR_NONE;
}

jvmtiError
JvmtiExport::add_module_opens(Handle module, Handle pkg_name, Handle to_module, TRAPS) {
  if (!Universe::is_module_initialized()) {
    return JVMTI_ERROR_NONE; // extra safety
  }
  assert(!module.is_null(), "module should always be set");
  assert(!to_module.is_null(), "to_module should always be set");
  assert(!pkg_name.is_null(), "pkg_name should always be set");

  // Invoke the addOpens method
  JavaValue result(T_VOID);
  JavaCalls::call_static(&result,
                         vmClasses::module_Modules_klass(),
                         vmSymbols::addOpens_name(),
                         vmSymbols::addExports_signature(),
                         module,
                         pkg_name,
                         to_module,
                         THREAD);

  if (HAS_PENDING_EXCEPTION) {
    Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
    LogTarget(Trace, jvmti) log;
    LogStream log_stream(log);
    java_lang_Throwable::print(PENDING_EXCEPTION, &log_stream);
    log_stream.cr();
    CLEAR_PENDING_EXCEPTION;
    if (ex_name == vmSymbols::java_lang_IllegalArgumentException()) {
      return JVMTI_ERROR_ILLEGAL_ARGUMENT;
    }
    return JVMTI_ERROR_INTERNAL;
  }
  return JVMTI_ERROR_NONE;
}

jvmtiError
JvmtiExport::add_module_uses(Handle module, Handle service, TRAPS) {
  if (!Universe::is_module_initialized()) {
    return JVMTI_ERROR_NONE; // extra safety
  }
  assert(!module.is_null(), "module should always be set");
  assert(!service.is_null(), "service should always be set");

  // Invoke the addUses method
  JavaValue result(T_VOID);
  JavaCalls::call_static(&result,
                         vmClasses::module_Modules_klass(),
                         vmSymbols::addUses_name(),
                         vmSymbols::addUses_signature(),
                         module,
                         service,
                         THREAD);

  if (HAS_PENDING_EXCEPTION) {
    LogTarget(Trace, jvmti) log;
    LogStream log_stream(log);
    java_lang_Throwable::print(PENDING_EXCEPTION, &log_stream);
    log_stream.cr();
    CLEAR_PENDING_EXCEPTION;
    return JVMTI_ERROR_INTERNAL;
  }
  return JVMTI_ERROR_NONE;
}

jvmtiError
JvmtiExport::add_module_provides(Handle module, Handle service, Handle impl_class, TRAPS) {
  if (!Universe::is_module_initialized()) {
    return JVMTI_ERROR_NONE; // extra safety
  }
  assert(!module.is_null(), "module should always be set");
  assert(!service.is_null(), "service should always be set");
  assert(!impl_class.is_null(), "impl_class should always be set");

  // Invoke the addProvides method
  JavaValue result(T_VOID);
  JavaCalls::call_static(&result,
                         vmClasses::module_Modules_klass(),
                         vmSymbols::addProvides_name(),
                         vmSymbols::addProvides_signature(),
                         module,
                         service,
                         impl_class,
                         THREAD);

  if (HAS_PENDING_EXCEPTION) {
    LogTarget(Trace, jvmti) log;
    LogStream log_stream(log);
    java_lang_Throwable::print(PENDING_EXCEPTION, &log_stream);
    log_stream.cr();
    CLEAR_PENDING_EXCEPTION;
    return JVMTI_ERROR_INTERNAL;
  }
  return JVMTI_ERROR_NONE;
}

void
JvmtiExport::decode_version_values(jint version, int * major, int * minor,
                                   int * micro) {
  *major = (version & JVMTI_VERSION_MASK_MAJOR) >> JVMTI_VERSION_SHIFT_MAJOR;
  *minor = (version & JVMTI_VERSION_MASK_MINOR) >> JVMTI_VERSION_SHIFT_MINOR;
  *micro = (version & JVMTI_VERSION_MASK_MICRO) >> JVMTI_VERSION_SHIFT_MICRO;
}

void JvmtiExport::enter_primordial_phase() {
  JvmtiEnvBase::set_phase(JVMTI_PHASE_PRIMORDIAL);
}

void JvmtiExport::enter_early_start_phase() {
  set_early_vmstart_recorded(true);
}

void JvmtiExport::enter_start_phase() {
  JvmtiEnvBase::set_phase(JVMTI_PHASE_START);
}

void JvmtiExport::enter_onload_phase() {
  JvmtiEnvBase::set_phase(JVMTI_PHASE_ONLOAD);
}

void JvmtiExport::enter_live_phase() {
  JvmtiEnvBase::set_phase(JVMTI_PHASE_LIVE);
}

//
// JVMTI events that the VM posts to the debugger and also startup agent
// and call the agent's premain() for java.lang.instrument.
//

void JvmtiExport::post_early_vm_start() {
  EVT_TRIG_TRACE(JVMTI_EVENT_VM_START, ("Trg Early VM start event triggered" ));

  // can now enable some events
  JvmtiEventController::vm_start();

  JvmtiEnvIterator it;
  for (JvmtiEnv* env = it.first(); env != NULL; env = it.next(env)) {
    // Only early vmstart envs post early VMStart event
    if (env->early_vmstart_env() && env->is_enabled(JVMTI_EVENT_VM_START)) {
      EVT_TRACE(JVMTI_EVENT_VM_START, ("Evt Early VM start event sent" ));
      JavaThread *thread  = JavaThread::current();
      JvmtiThreadEventMark jem(thread);
      JvmtiJavaThreadEventTransition jet(thread);
      jvmtiEventVMStart callback = env->callbacks()->VMStart;
      if (callback != NULL) {
        (*callback)(env->jvmti_external(), jem.jni_env());
      }
    }
  }
}

void JvmtiExport::post_vm_start() {
  EVT_TRIG_TRACE(JVMTI_EVENT_VM_START, ("Trg VM start event triggered" ));

  // can now enable some events
  JvmtiEventController::vm_start();

  JvmtiEnvIterator it;
  for (JvmtiEnv* env = it.first(); env != NULL; env = it.next(env)) {
    // Early vmstart envs do not post normal VMStart event
    if (!env->early_vmstart_env() && env->is_enabled(JVMTI_EVENT_VM_START)) {
      EVT_TRACE(JVMTI_EVENT_VM_START, ("Evt VM start event sent" ));

      JavaThread *thread  = JavaThread::current();
      JvmtiThreadEventMark jem(thread);
      JvmtiJavaThreadEventTransition jet(thread);
      jvmtiEventVMStart callback = env->callbacks()->VMStart;
      if (callback != NULL) {
        (*callback)(env->jvmti_external(), jem.jni_env());
      }
    }
  }
}

static OopStorage* _jvmti_oop_storage = NULL;
static OopStorage* _weak_tag_storage = NULL;

OopStorage* JvmtiExport::jvmti_oop_storage() {
  assert(_jvmti_oop_storage != NULL, "not yet initialized");
  return _jvmti_oop_storage;
}

OopStorage* JvmtiExport::weak_tag_storage() {
  assert(_weak_tag_storage != NULL, "not yet initialized");
  return _weak_tag_storage;
}

void JvmtiExport::initialize_oop_storage() {
  // OopStorage needs to be created early in startup and unconditionally
  // because of OopStorageSet static array indices.
  _jvmti_oop_storage = OopStorageSet::create_strong("JVMTI OopStorage", mtServiceability);
  _weak_tag_storage  = OopStorageSet::create_weak("JVMTI Tag Weak OopStorage", mtServiceability);
  _weak_tag_storage->register_num_dead_callback(&JvmtiTagMap::gc_notification);
}

void JvmtiExport::post_vm_initialized() {
  EVT_TRIG_TRACE(JVMTI_EVENT_VM_INIT, ("Trg VM init event triggered" ));

  // can now enable events
  JvmtiEventController::vm_init();

  JvmtiEnvIterator it;
  for (JvmtiEnv* env = it.first(); env != NULL; env = it.next(env)) {
    if (env->is_enabled(JVMTI_EVENT_VM_INIT)) {
      EVT_TRACE(JVMTI_EVENT_VM_INIT, ("Evt VM init event sent" ));

      JavaThread *thread  = JavaThread::current();
      JvmtiThreadEventMark jem(thread);
      JvmtiJavaThreadEventTransition jet(thread);
      jvmtiEventVMInit callback = env->callbacks()->VMInit;
      if (callback != NULL) {
        (*callback)(env->jvmti_external(), jem.jni_env(), jem.jni_thread());
      }
    }
  }
}


void JvmtiExport::post_vm_death() {
  EVT_TRIG_TRACE(JVMTI_EVENT_VM_DEATH, ("Trg VM death event triggered" ));

  JvmtiTagMap::flush_all_object_free_events();

  JvmtiEnvIterator it;
  for (JvmtiEnv* env = it.first(); env != NULL; env = it.next(env)) {
    if (env->is_enabled(JVMTI_EVENT_VM_DEATH)) {
      EVT_TRACE(JVMTI_EVENT_VM_DEATH, ("Evt VM death event sent" ));

      JavaThread *thread  = JavaThread::current();
      JvmtiEventMark jem(thread);
      JvmtiJavaThreadEventTransition jet(thread);
      jvmtiEventVMDeath callback = env->callbacks()->VMDeath;
      if (callback != NULL) {
        (*callback)(env->jvmti_external(), jem.jni_env());
      }
    }
  }

  JvmtiEnvBase::set_phase(JVMTI_PHASE_DEAD);
  JvmtiEventController::vm_death();
}

char**
JvmtiExport::get_all_native_method_prefixes(int* count_ptr) {
  // Have to grab JVMTI thread state lock to be sure environment doesn't
  // go away while we iterate them.  No locks during VM bring-up.
  if (Threads::number_of_threads() == 0 || SafepointSynchronize::is_at_safepoint()) {
    return JvmtiEnvBase::get_all_native_method_prefixes(count_ptr);
  } else {
    MutexLocker mu(JvmtiThreadState_lock);
    return JvmtiEnvBase::get_all_native_method_prefixes(count_ptr);
  }
}

// Convert an external thread reference to a JavaThread found on the
// specified ThreadsList. The ThreadsListHandle in the caller "protects"
// the returned JavaThread *.
//
// If thread_oop_p is not NULL, then the caller wants to use the oop
// after this call so the oop is returned. On success, *jt_pp is set
// to the converted JavaThread * and JVMTI_ERROR_NONE is returned.
// On error, returns various JVMTI_ERROR_* values.
//
jvmtiError
JvmtiExport::cv_external_thread_to_JavaThread(ThreadsList * t_list,
                                              jthread thread,
                                              JavaThread ** jt_pp,
                                              oop * thread_oop_p) {
  assert(t_list != NULL, "must have a ThreadsList");
  assert(jt_pp != NULL, "must have a return JavaThread pointer");
  // thread_oop_p is optional so no assert()

  if (thread_oop_p != NULL) {
    *thread_oop_p = NULL;
  }

  oop thread_oop = JNIHandles::resolve_external_guard(thread);
  if (thread_oop == NULL) {
    // NULL jthread, GC'ed jthread or a bad JNI handle.
    return JVMTI_ERROR_INVALID_THREAD;
  }
  // Looks like an oop at this point.

  if (!thread_oop->is_a(vmClasses::Thread_klass())) {
    // The oop is not a java.lang.Thread.
    return JVMTI_ERROR_INVALID_THREAD;
  }
  // Looks like a java.lang.Thread oop at this point.

  if (thread_oop_p != NULL) {
    // Return the oop to the caller; the caller may still want
    // the oop even if this function returns an error.
    *thread_oop_p = thread_oop;
  }

  JavaThread * java_thread = java_lang_Thread::thread(thread_oop);
  if (java_thread == NULL) {
    if (java_lang_VirtualThread::is_instance(thread_oop)) {
      return JVMTI_ERROR_INVALID_THREAD;
    }
    // The java.lang.Thread does not contain a JavaThread * so it has
    // not yet run or it has died.
    return JVMTI_ERROR_THREAD_NOT_ALIVE;
  }
  // Looks like a live JavaThread at this point.

  // We do not check the EnableThreadSMRExtraValidityChecks option
  // for this includes() call because JVM/TI's spec is tighter.
  if (!t_list->includes(java_thread)) {
    // Not on the JavaThreads list so it is not alive.
    return JVMTI_ERROR_THREAD_NOT_ALIVE;
  }

  // Return a live JavaThread that is "protected" by the
  // ThreadsListHandle in the caller.
  *jt_pp = java_thread;

  return JVMTI_ERROR_NONE;
}

// Convert an oop to a JavaThread found on the specified ThreadsList.
// The ThreadsListHandle in the caller "protects" the returned
// JavaThread *.
//
// On success, *jt_pp is set to the converted JavaThread * and
// JVMTI_ERROR_NONE is returned. On error, returns various
// JVMTI_ERROR_* values.
//
jvmtiError
JvmtiExport::cv_oop_to_JavaThread(ThreadsList * t_list, oop thread_oop,
                                  JavaThread ** jt_pp) {
  assert(t_list != NULL, "must have a ThreadsList");
  assert(thread_oop != NULL, "must have an oop");
  assert(jt_pp != NULL, "must have a return JavaThread pointer");

  if (!thread_oop->is_a(vmClasses::Thread_klass())) {
    // The oop is not a java.lang.Thread.
    return JVMTI_ERROR_INVALID_THREAD;
  }
  // Looks like a java.lang.Thread oop at this point.

  JavaThread * java_thread = java_lang_Thread::thread(thread_oop);
  if (java_thread == NULL) {
    // The java.lang.Thread does not contain a JavaThread * so it has
    // not yet run or it has died.
    return JVMTI_ERROR_THREAD_NOT_ALIVE;
  }
  // Looks like a live JavaThread at this point.

  // We do not check the EnableThreadSMRExtraValidityChecks option
  // for this includes() call because JVM/TI's spec is tighter.
  if (!t_list->includes(java_thread)) {
    // Not on the JavaThreads list so it is not alive.
    return JVMTI_ERROR_THREAD_NOT_ALIVE;
  }

  // Return a live JavaThread that is "protected" by the
  // ThreadsListHandle in the caller.
  *jt_pp = java_thread;

  return JVMTI_ERROR_NONE;
}

class JvmtiClassFileLoadHookPoster : public StackObj {
 private:
  Symbol*            _h_name;
  Handle               _class_loader;
  Handle               _h_protection_domain;
  unsigned char **     _data_ptr;
  unsigned char **     _end_ptr;
  JavaThread *         _thread;
  jint                 _curr_len;
  unsigned char *      _curr_data;
  JvmtiEnv *           _curr_env;
  JvmtiCachedClassFileData ** _cached_class_file_ptr;
  JvmtiThreadState *   _state;
  Klass*               _class_being_redefined;
  JvmtiClassLoadKind   _load_kind;
  bool                 _has_been_modified;

 public:
  inline JvmtiClassFileLoadHookPoster(Symbol* h_name, Handle class_loader,
                                      Handle h_protection_domain,
                                      unsigned char **data_ptr, unsigned char **end_ptr,
                                      JvmtiCachedClassFileData **cache_ptr) {
    _h_name = h_name;
    _class_loader = class_loader;
    _h_protection_domain = h_protection_domain;
    _data_ptr = data_ptr;
    _end_ptr = end_ptr;
    _thread = JavaThread::current();
    _curr_len = *end_ptr - *data_ptr;
    _curr_data = *data_ptr;
    _curr_env = NULL;
    _cached_class_file_ptr = cache_ptr;
    _has_been_modified = false;

    assert(!_thread->is_in_any_VTMS_transition(), "CFLH events are not allowed in any VTMS transition");
    _state = _thread->jvmti_thread_state();
    if (_state != NULL) {
      _class_being_redefined = _state->get_class_being_redefined();
      _load_kind = _state->get_class_load_kind();
      Klass* klass = (_class_being_redefined == NULL) ? NULL : _class_being_redefined;
      if (_load_kind != jvmti_class_load_kind_load && klass != NULL) {
        ModuleEntry* module_entry = InstanceKlass::cast(klass)->module();
        assert(module_entry != NULL, "module_entry should always be set");
        if (module_entry->is_named() &&
            module_entry->module() != NULL &&
            !module_entry->has_default_read_edges()) {
          if (!module_entry->set_has_default_read_edges()) {
            // We won a potential race.
            // Add read edges to the unnamed modules of the bootstrap and app class loaders
            Handle class_module(_thread, module_entry->module()); // Obtain j.l.r.Module
            JvmtiExport::add_default_read_edges(class_module, _thread);
          }
        }
      }
      // Clear class_being_redefined flag here. The action
      // from agent handler could generate a new class file load
      // hook event and if it is not cleared the new event generated
      // from regular class file load could have this stale redefined
      // class handle info.
      _state->clear_class_being_redefined();
    } else {
      // redefine and retransform will always set the thread state
      _class_being_redefined = NULL;
      _load_kind = jvmti_class_load_kind_load;
    }
  }

  void post() {
    post_all_envs();
    copy_modified_data();
  }

  bool has_been_modified() { return _has_been_modified; }

 private:
  void post_all_envs() {
    if (_load_kind != jvmti_class_load_kind_retransform) {
      // for class load and redefine,
      // call the non-retransformable agents
      JvmtiEnvIterator it;
      for (JvmtiEnv* env = it.first(); env != NULL; env = it.next(env)) {
        if (!env->is_retransformable() && env->is_enabled(JVMTI_EVENT_CLASS_FILE_LOAD_HOOK)) {
          // non-retransformable agents cannot retransform back,
          // so no need to cache the original class file bytes
          post_to_env(env, false);
        }
      }
    }
    JvmtiEnvIterator it;
    for (JvmtiEnv* env = it.first(); env != NULL; env = it.next(env)) {
      // retransformable agents get all events
      if (env->is_retransformable() && env->is_enabled(JVMTI_EVENT_CLASS_FILE_LOAD_HOOK)) {
        // retransformable agents need to cache the original class file
        // bytes if changes are made via the ClassFileLoadHook
        post_to_env(env, true);
      }
    }
  }

  void post_to_env(JvmtiEnv* env, bool caching_needed) {
    if (env->phase() == JVMTI_PHASE_PRIMORDIAL && !env->early_class_hook_env()) {
      return;
    }
    unsigned char *new_data = NULL;
    jint new_len = 0;
    JvmtiClassFileLoadEventMark jem(_thread, _h_name, _class_loader,
                                    _h_protection_domain,
                                    _class_being_redefined);
    JvmtiJavaThreadEventTransition jet(_thread);
    jvmtiEventClassFileLoadHook callback = env->callbacks()->ClassFileLoadHook;
    if (callback != NULL) {
      (*callback)(env->jvmti_external(), jem.jni_env(),
                  jem.class_being_redefined(),
                  jem.jloader(), jem.class_name(),
                  jem.protection_domain(),
                  _curr_len, _curr_data,
                  &new_len, &new_data);
    }
    if (new_data != NULL) {
      // this agent has modified class data.
      _has_been_modified = true;
      if (caching_needed && *_cached_class_file_ptr == NULL) {
        // data has been changed by the new retransformable agent
        // and it hasn't already been cached, cache it
        JvmtiCachedClassFileData *p;
        p = (JvmtiCachedClassFileData *)os::malloc(
          offset_of(JvmtiCachedClassFileData, data) + _curr_len, mtInternal);
        if (p == NULL) {
          vm_exit_out_of_memory(offset_of(JvmtiCachedClassFileData, data) + _curr_len,
            OOM_MALLOC_ERROR,
            "unable to allocate cached copy of original class bytes");
        }
        p->length = _curr_len;
        memcpy(p->data, _curr_data, _curr_len);
        *_cached_class_file_ptr = p;
      }

      if (_curr_data != *_data_ptr) {
        // curr_data is previous agent modified class data.
        // And this has been changed by the new agent so
        // we can delete it now.
        _curr_env->Deallocate(_curr_data);
      }

      // Class file data has changed by the current agent.
      _curr_data = new_data;
      _curr_len = new_len;
      // Save the current agent env we need this to deallocate the
      // memory allocated by this agent.
      _curr_env = env;
    }
  }

  void copy_modified_data() {
    // if one of the agent has modified class file data.
    // Copy modified class data to new resources array.
    if (_curr_data != *_data_ptr) {
      *_data_ptr = NEW_RESOURCE_ARRAY(u1, _curr_len);
      memcpy(*_data_ptr, _curr_data, _curr_len);
      *_end_ptr = *_data_ptr + _curr_len;
      _curr_env->Deallocate(_curr_data);
    }
  }
};

bool JvmtiExport::is_early_phase() {
  return JvmtiEnvBase::get_phase() <= JVMTI_PHASE_PRIMORDIAL;
}

bool JvmtiExport::has_early_class_hook_env() {
  JvmtiEnvIterator it;
  for (JvmtiEnv* env = it.first(); env != NULL; env = it.next(env)) {
    if (env->early_class_hook_env()) {
      return true;
    }
  }
  return false;
}

bool JvmtiExport::_should_post_class_file_load_hook = false;

// this entry is for class file load hook on class load, redefine and retransform
bool JvmtiExport::post_class_file_load_hook(Symbol* h_name,
                                            Handle class_loader,
                                            Handle h_protection_domain,
                                            unsigned char **data_ptr,
                                            unsigned char **end_ptr,
                                            JvmtiCachedClassFileData **cache_ptr) {
  if (JvmtiEnv::get_phase() < JVMTI_PHASE_PRIMORDIAL) {
    return false;
  }
  if (JavaThread::current()->is_in_tmp_VTMS_transition()) {
    return false; // skip CFLH events in tmp VTMS transition
  }

  JvmtiClassFileLoadHookPoster poster(h_name, class_loader,
                                      h_protection_domain,
                                      data_ptr, end_ptr,
                                      cache_ptr);
  poster.post();
  return poster.has_been_modified();
}

void JvmtiExport::report_unsupported(bool on) {
  // If any JVMTI service is turned on, we need to exit before native code
  // tries to access nonexistent services.
  if (on) {
    vm_exit_during_initialization("Java Kernel does not support JVMTI.");
  }
}


static inline Klass* oop_to_klass(oop obj) {
  Klass* k = obj->klass();

  // if the object is a java.lang.Class then return the java mirror
  if (k == vmClasses::Class_klass()) {
    if (!java_lang_Class::is_primitive(obj)) {
      k = java_lang_Class::as_Klass(obj);
      assert(k != NULL, "class for non-primitive mirror must exist");
    }
  }
  return k;
}

class JvmtiObjectAllocEventMark : public JvmtiClassEventMark  {
 private:
   jobject _jobj;
   jlong    _size;
 public:
   JvmtiObjectAllocEventMark(JavaThread *thread, oop obj) : JvmtiClassEventMark(thread, oop_to_klass(obj)) {
     _jobj = (jobject)to_jobject(obj);
     _size = obj->size() * wordSize;
   };
   jobject jni_jobject() { return _jobj; }
   jlong size() { return _size; }
};

class JvmtiCompiledMethodLoadEventMark : public JvmtiMethodEventMark {
 private:
  jint _code_size;
  const void *_code_data;
  jint _map_length;
  jvmtiAddrLocationMap *_map;
  const void *_compile_info;
 public:
  JvmtiCompiledMethodLoadEventMark(JavaThread *thread, nmethod *nm, void* compile_info_ptr = NULL)
          : JvmtiMethodEventMark(thread,methodHandle(thread, nm->method())) {
    _code_data = nm->code_begin();
    _code_size = nm->code_size();
    _compile_info = compile_info_ptr; // Set void pointer of compiledMethodLoad Event. Default value is NULL.
    JvmtiCodeBlobEvents::build_jvmti_addr_location_map(nm, &_map, &_map_length);
  }
  ~JvmtiCompiledMethodLoadEventMark() {
     FREE_C_HEAP_ARRAY(jvmtiAddrLocationMap, _map);
  }

  jint code_size() { return _code_size; }
  const void *code_data() { return _code_data; }
  jint map_length() { return _map_length; }
  const jvmtiAddrLocationMap* map() { return _map; }
  const void *compile_info() { return _compile_info; }
};



class JvmtiMonitorEventMark : public JvmtiVirtualThreadEventMark {
private:
  jobject _jobj;
public:
  JvmtiMonitorEventMark(JavaThread *thread, oop object)
          : JvmtiVirtualThreadEventMark(thread){
     _jobj = to_jobject(object);
  }
  jobject jni_object() { return _jobj; }
};

///////////////////////////////////////////////////////////////
//
// pending CompiledMethodUnload support
//

void JvmtiExport::post_compiled_method_unload(
       jmethodID method, const void *code_begin) {
  if (JvmtiEnv::get_phase() < JVMTI_PHASE_PRIMORDIAL) {
    return;
  }
  JavaThread* thread = JavaThread::current();
  EVT_TRIG_TRACE(JVMTI_EVENT_COMPILED_METHOD_UNLOAD,
                 ("[%s] method compile unload event triggered",
                  JvmtiTrace::safe_get_thread_name(thread)));

  // post the event for each environment that has this event enabled.
  JvmtiEnvIterator it;
  for (JvmtiEnv* env = it.first(); env != NULL; env = it.next(env)) {
    if (env->is_enabled(JVMTI_EVENT_COMPILED_METHOD_UNLOAD)) {
      if (env->phase() == JVMTI_PHASE_PRIMORDIAL) {
        continue;
      }
      EVT_TRACE(JVMTI_EVENT_COMPILED_METHOD_UNLOAD,
                ("[%s] class compile method unload event sent jmethodID " PTR_FORMAT,
                 JvmtiTrace::safe_get_thread_name(thread), p2i(method)));

      ResourceMark rm(thread);

      JvmtiEventMark jem(thread);
      JvmtiJavaThreadEventTransition jet(thread);
      jvmtiEventCompiledMethodUnload callback = env->callbacks()->CompiledMethodUnload;
      if (callback != NULL) {
        (*callback)(env->jvmti_external(), method, code_begin);
      }
    }
  }
}

///////////////////////////////////////////////////////////////
//
// JvmtiExport
//

void JvmtiExport::post_raw_breakpoint(JavaThread *thread, Method* method, address location) {
  HandleMark hm(thread);
  methodHandle mh(thread, method);

  JvmtiThreadState *state = thread->jvmti_thread_state();
  if (state == NULL) {
    return;
  }
  if (thread->is_in_any_VTMS_transition()) {
    return; // no events should be posted if thread is in any VTMS transition
  }

  EVT_TRIG_TRACE(JVMTI_EVENT_BREAKPOINT, ("[%s] Trg Breakpoint triggered",
                      JvmtiTrace::safe_get_thread_name(thread)));
  JvmtiEnvThreadStateIterator it(state);
  for (JvmtiEnvThreadState* ets = it.first(); ets != NULL; ets = it.next(ets)) {
    ets->compare_and_set_current_location(mh(), location, JVMTI_EVENT_BREAKPOINT);
    if (!ets->breakpoint_posted() && ets->is_enabled(JVMTI_EVENT_BREAKPOINT)) {
      ThreadState old_os_state = thread->osthread()->get_state();
      thread->osthread()->set_state(BREAKPOINTED);
      EVT_TRACE(JVMTI_EVENT_BREAKPOINT, ("[%s] Evt Breakpoint sent %s.%s @ " INTX_FORMAT,
                     JvmtiTrace::safe_get_thread_name(thread),
                     (mh() == NULL) ? "NULL" : mh()->klass_name()->as_C_string(),
                     (mh() == NULL) ? "NULL" : mh()->name()->as_C_string(),
                     location - mh()->code_base() ));

      JvmtiEnv *env = ets->get_env();
      JvmtiLocationEventMark jem(thread, mh, location);
      JvmtiJavaThreadEventTransition jet(thread);
      jvmtiEventBreakpoint callback = env->callbacks()->Breakpoint;
      if (callback != NULL) {
        (*callback)(env->jvmti_external(), jem.jni_env(), jem.jni_thread(),
                    jem.jni_methodID(), jem.location());
      }

      ets->set_breakpoint_posted();
      thread->osthread()->set_state(old_os_state);
    }
  }
}

//////////////////////////////////////////////////////////////////////////////

bool              JvmtiExport::_can_get_source_debug_extension            = false;
bool              JvmtiExport::_can_maintain_original_method_order        = false;
bool              JvmtiExport::_can_post_interpreter_events               = false;
bool              JvmtiExport::_can_post_on_exceptions                    = false;
bool              JvmtiExport::_can_post_breakpoint                       = false;
bool              JvmtiExport::_can_post_field_access                     = false;
bool              JvmtiExport::_can_post_field_modification               = false;
bool              JvmtiExport::_can_post_method_entry                     = false;
bool              JvmtiExport::_can_post_method_exit                      = false;
bool              JvmtiExport::_can_post_frame_pop                        = false;
bool              JvmtiExport::_can_pop_frame                             = false;
bool              JvmtiExport::_can_force_early_return                    = false;
bool              JvmtiExport::_can_support_virtual_threads               = false;
bool              JvmtiExport::_can_get_owned_monitor_info                = false;

bool              JvmtiExport::_early_vmstart_recorded                    = false;

bool              JvmtiExport::_should_post_single_step                   = false;
bool              JvmtiExport::_should_post_field_access                  = false;
bool              JvmtiExport::_should_post_field_modification            = false;
bool              JvmtiExport::_should_post_class_load                    = false;
bool              JvmtiExport::_should_post_class_prepare                 = false;
bool              JvmtiExport::_should_post_class_unload                  = false;
bool              JvmtiExport::_should_post_thread_life                   = false;
bool              JvmtiExport::_should_clean_up_heap_objects              = false;
bool              JvmtiExport::_should_post_native_method_bind            = false;
bool              JvmtiExport::_should_post_dynamic_code_generated        = false;
bool              JvmtiExport::_should_post_data_dump                     = false;
bool              JvmtiExport::_should_post_compiled_method_load          = false;
bool              JvmtiExport::_should_post_compiled_method_unload        = false;
bool              JvmtiExport::_should_post_monitor_contended_enter       = false;
bool              JvmtiExport::_should_post_monitor_contended_entered     = false;
bool              JvmtiExport::_should_post_monitor_wait                  = false;
bool              JvmtiExport::_should_post_monitor_waited                = false;
bool              JvmtiExport::_should_post_garbage_collection_start      = false;
bool              JvmtiExport::_should_post_garbage_collection_finish     = false;
bool              JvmtiExport::_should_post_object_free                   = false;
bool              JvmtiExport::_should_post_resource_exhausted            = false;
bool              JvmtiExport::_should_post_vm_object_alloc               = false;
bool              JvmtiExport::_should_post_sampled_object_alloc          = false;
bool              JvmtiExport::_should_post_on_exceptions                 = false;
bool              JvmtiExport::_should_post_vthread_start                 = false;
bool              JvmtiExport::_should_post_vthread_end                   = false;
bool              JvmtiExport::_should_post_vthread_mount                 = false;
bool              JvmtiExport::_should_post_vthread_unmount               = false;

////////////////////////////////////////////////////////////////////////////////////////////////


void JvmtiExport::check_vthread_and_suspend_at_safepoint(JavaThread *thread) {
  oop vt = thread->jvmti_vthread();

  if (vt != NULL && java_lang_VirtualThread::is_instance(vt)) {
    int64_t id = java_lang_Thread::thread_id(vt);

    ThreadBlockInVM tbivm(thread);
    MonitorLocker ml(JvmtiVTMSTransition_lock, Mutex::_no_safepoint_check_flag);

    // block while vthread is externally suspended
    while (JvmtiVTSuspender::is_vthread_suspended(id)) {
      ml.wait();
    }
  }
}

//
// JVMTI single step management
//
void JvmtiExport::at_single_stepping_point(JavaThread *thread, Method* method, address location) {
  assert(JvmtiExport::should_post_single_step(), "must be single stepping");

  HandleMark hm(thread);
  methodHandle mh(thread, method);

  // update information about current location and post a step event
  JvmtiThreadState *state = thread->jvmti_thread_state();
  if (state == NULL) {
    return;
  }
  EVT_TRIG_TRACE(JVMTI_EVENT_SINGLE_STEP, ("[%s] Trg Single Step triggered",
                      JvmtiTrace::safe_get_thread_name(thread)));
  if (!state->hide_single_stepping()) {
    if (state->is_pending_step_for_popframe()) {
      state->process_pending_step_for_popframe();
    }
    if (state->is_pending_step_for_earlyret()) {
      state->process_pending_step_for_earlyret();
    }
    JvmtiExport::post_single_step(thread, mh(), location);
  }
}


void JvmtiExport::expose_single_stepping(JavaThread *thread) {
  JvmtiThreadState *state = thread->jvmti_thread_state();
  if (state != NULL) {
    state->clear_hide_single_stepping();
  }
}


bool JvmtiExport::hide_single_stepping(JavaThread *thread) {
  JvmtiThreadState *state = thread->jvmti_thread_state();
  if (state != NULL && state->is_enabled(JVMTI_EVENT_SINGLE_STEP)) {
    state->set_hide_single_stepping();
    return true;
  } else {
    return false;
  }
}

void JvmtiExport::post_class_load(JavaThread *thread, Klass* klass) {
  if (JvmtiEnv::get_phase() < JVMTI_PHASE_PRIMORDIAL) {
    return;
  }
  HandleMark hm(thread);

  JvmtiThreadState* state = thread->jvmti_thread_state();
  if (state == NULL) {
    return;
  }
  if (thread->is_in_tmp_VTMS_transition()) {
    return; // skip ClassLoad events in tmp VTMS transition
  }
  assert(!thread->is_in_any_VTMS_transition(), "class load events are not allowed in any VTMS transition");

  EVT_TRIG_TRACE(JVMTI_EVENT_CLASS_LOAD, ("[%s] Trg Class Load triggered",
                      JvmtiTrace::safe_get_thread_name(thread)));
  JvmtiEnvThreadStateIterator it(state);
  for (JvmtiEnvThreadState* ets = it.first(); ets != NULL; ets = it.next(ets)) {
    if (ets->is_enabled(JVMTI_EVENT_CLASS_LOAD)) {
      JvmtiEnv *env = ets->get_env();
      if (env->phase() == JVMTI_PHASE_PRIMORDIAL) {
        continue;
      }
      EVT_TRACE(JVMTI_EVENT_CLASS_LOAD, ("[%s] Evt Class Load sent %s",
                                         JvmtiTrace::safe_get_thread_name(thread),
                                         klass==NULL? "NULL" : klass->external_name() ));
      JvmtiClassEventMark jem(thread, klass);
      JvmtiJavaThreadEventTransition jet(thread);
      jvmtiEventClassLoad callback = env->callbacks()->ClassLoad;
      if (callback != NULL) {
        (*callback)(env->jvmti_external(), jem.jni_env(), jem.jni_thread(), jem.jni_class());
      }
    }
  }
}


void JvmtiExport::post_class_prepare(JavaThread *thread, Klass* klass) {
  if (JvmtiEnv::get_phase() < JVMTI_PHASE_PRIMORDIAL) {
    return;
  }
  HandleMark hm(thread);

  JvmtiThreadState* state = thread->jvmti_thread_state();
  if (state == NULL) {
    return;
  }
  if (thread->is_in_tmp_VTMS_transition()) {
    return; // skip ClassPrepare events in tmp VTMS transition
  }
  assert(!thread->is_in_any_VTMS_transition(), "class prepare events are not allowed in any VTMS transition");

  EVT_TRIG_TRACE(JVMTI_EVENT_CLASS_PREPARE, ("[%s] Trg Class Prepare triggered",
                      JvmtiTrace::safe_get_thread_name(thread)));
  JvmtiEnvThreadStateIterator it(state);
  for (JvmtiEnvThreadState* ets = it.first(); ets != NULL; ets = it.next(ets)) {
    if (ets->is_enabled(JVMTI_EVENT_CLASS_PREPARE)) {
      JvmtiEnv *env = ets->get_env();
      if (env->phase() == JVMTI_PHASE_PRIMORDIAL) {
        continue;
      }
      EVT_TRACE(JVMTI_EVENT_CLASS_PREPARE, ("[%s] Evt Class Prepare sent %s",
                                            JvmtiTrace::safe_get_thread_name(thread),
                                            klass==NULL? "NULL" : klass->external_name() ));
      JvmtiClassEventMark jem(thread, klass);
      JvmtiJavaThreadEventTransition jet(thread);
      jvmtiEventClassPrepare callback = env->callbacks()->ClassPrepare;
      if (callback != NULL) {
        (*callback)(env->jvmti_external(), jem.jni_env(), jem.jni_thread(), jem.jni_class());
      }
    }
  }
}

void JvmtiExport::post_class_unload(Klass* klass) {
  if (JvmtiEnv::get_phase() < JVMTI_PHASE_PRIMORDIAL) {
    return;
  }

  // postings to the service thread so that it can perform them in a safe
  // context and in-order.
  ResourceMark rm;
  // JvmtiDeferredEvent copies the string.
  JvmtiDeferredEvent event = JvmtiDeferredEvent::class_unload_event(klass->name()->as_C_string());
  ServiceThread::enqueue_deferred_event(&event);
}


void JvmtiExport::post_class_unload_internal(const char* name) {
  if (JvmtiEnv::get_phase() < JVMTI_PHASE_PRIMORDIAL) {
    return;
  }
  assert(Thread::current()->is_service_thread(), "must be called from ServiceThread");
  JavaThread *thread = JavaThread::current();
  HandleMark hm(thread);

  EVT_TRIG_TRACE(EXT_EVENT_CLASS_UNLOAD, ("[?] Trg Class Unload triggered" ));
  if (JvmtiEventController::is_enabled((jvmtiEvent)EXT_EVENT_CLASS_UNLOAD)) {

    JvmtiEnvIterator it;
    for (JvmtiEnv* env = it.first(); env != NULL; env = it.next(env)) {
      if (env->phase() == JVMTI_PHASE_PRIMORDIAL) {
        continue;
      }
      if (env->is_enabled((jvmtiEvent)EXT_EVENT_CLASS_UNLOAD)) {
        EVT_TRACE(EXT_EVENT_CLASS_UNLOAD, ("[?] Evt Class Unload sent %s", name));

        JvmtiEventMark jem(thread);
        JvmtiJavaThreadEventTransition jet(thread);
        jvmtiExtensionEvent callback = env->ext_callbacks()->ClassUnload;
        if (callback != NULL) {
          (*callback)(env->jvmti_external(), jem.jni_env(), name);
        }
      }
    }
  }
}


void JvmtiExport::post_thread_start(JavaThread *thread) {
  if (JvmtiEnv::get_phase() < JVMTI_PHASE_PRIMORDIAL) {
    return;
  }
  assert(thread->thread_state() == _thread_in_vm, "must be in vm state");

  EVT_TRIG_TRACE(JVMTI_EVENT_THREAD_START, ("[%s] Trg Thread Start event triggered",
                      JvmtiTrace::safe_get_thread_name(thread)));

  // do JVMTI thread initialization (if needed)
  JvmtiEventController::thread_started(thread);

  // Do not post thread start event for hidden java thread.
  if (JvmtiEventController::is_enabled(JVMTI_EVENT_THREAD_START) &&
      !thread->is_hidden_from_external_view()) {
    JvmtiEnvIterator it;
    for (JvmtiEnv* env = it.first(); env != NULL; env = it.next(env)) {
      if (env->phase() == JVMTI_PHASE_PRIMORDIAL) {
        continue;
      }
      if (env->is_enabled(JVMTI_EVENT_THREAD_START)) {
        EVT_TRACE(JVMTI_EVENT_THREAD_START, ("[%s] Evt Thread Start event sent",
                     JvmtiTrace::safe_get_thread_name(thread) ));

        JvmtiVirtualThreadEventMark jem(thread);
        JvmtiJavaThreadEventTransition jet(thread);
        jvmtiEventThreadStart callback = env->callbacks()->ThreadStart;
        if (callback != NULL) {
          (*callback)(env->jvmti_external(), jem.jni_env(), jem.jni_thread());
        }
      }
    }
  }
}


void JvmtiExport::post_thread_end(JavaThread *thread) {
  if (JvmtiEnv::get_phase() < JVMTI_PHASE_PRIMORDIAL) {
    return;
  }
  EVT_TRIG_TRACE(JVMTI_EVENT_THREAD_END, ("[%s] Trg Thread End event triggered",
                      JvmtiTrace::safe_get_thread_name(thread)));

  JvmtiThreadState *state = thread->jvmti_thread_state();
  if (state == NULL) {
    return;
  }

  // Do not post thread end event for hidden java thread.
  if (state->is_enabled(JVMTI_EVENT_THREAD_END) &&
      !thread->is_hidden_from_external_view()) {

    JvmtiEnvThreadStateIterator it(state);
    for (JvmtiEnvThreadState* ets = it.first(); ets != NULL; ets = it.next(ets)) {
      if (ets->is_enabled(JVMTI_EVENT_THREAD_END)) {
        JvmtiEnv *env = ets->get_env();
        if (env->phase() == JVMTI_PHASE_PRIMORDIAL) {
          continue;
        }
        EVT_TRACE(JVMTI_EVENT_THREAD_END, ("[%s] Evt Thread End event sent",
                     JvmtiTrace::safe_get_thread_name(thread) ));

        JvmtiVirtualThreadEventMark jem(thread);
        JvmtiJavaThreadEventTransition jet(thread);
        jvmtiEventThreadEnd callback = env->callbacks()->ThreadEnd;
        if (callback != NULL) {
          (*callback)(env->jvmti_external(), jem.jni_env(), jem.jni_thread());
        }
      }
    }
  }
}


void JvmtiExport::post_vthread_start(jobject vthread) {
  if (JvmtiEnv::get_phase() < JVMTI_PHASE_PRIMORDIAL) {
    return;
  }
  EVT_TRIG_TRACE(JVMTI_EVENT_VIRTUAL_THREAD_START, ("[%p] Trg Virtual Thread Start event triggered", vthread));

  JavaThread *cur_thread = JavaThread::current();
  JvmtiThreadState *state = cur_thread->jvmti_thread_state();
  if (state == NULL) {
    return;
  }

  if (state->is_enabled(JVMTI_EVENT_VIRTUAL_THREAD_START)) {
    JvmtiEnvThreadStateIterator it(state);

    for (JvmtiEnvThreadState* ets = it.first(); ets != NULL; ets = it.next(ets)) {
      JvmtiEnv *env = ets->get_env();
      if (env->phase() == JVMTI_PHASE_PRIMORDIAL) {
        continue;
      }
      if (ets->is_enabled(JVMTI_EVENT_VIRTUAL_THREAD_START)) {
        EVT_TRACE(JVMTI_EVENT_VIRTUAL_THREAD_START, ("[%p] Evt Virtual Thread Start event sent", vthread));

        JvmtiVirtualThreadEventMark jem(cur_thread);
        JvmtiJavaThreadEventTransition jet(cur_thread);
        jvmtiEventVirtualThreadStart callback = env->callbacks()->VirtualThreadStart;
        if (callback != NULL) {
          (*callback)(env->jvmti_external(), jem.jni_env(), jem.jni_thread());
        }
      }
    }
  }
}

void JvmtiExport::post_vthread_end(jobject vthread) {
  if (JvmtiEnv::get_phase() < JVMTI_PHASE_PRIMORDIAL) {
    return;
  }
  EVT_TRIG_TRACE(JVMTI_EVENT_VIRTUAL_THREAD_END, ("[%p] Trg Virtual Thread End event triggered", vthread));

  JavaThread *cur_thread = JavaThread::current();
  JvmtiThreadState *state = cur_thread->jvmti_thread_state();
  if (state == NULL) {
    return;
  }

  if (state->is_enabled(JVMTI_EVENT_VIRTUAL_THREAD_END)) {
    JvmtiEnvThreadStateIterator it(state);

    for (JvmtiEnvThreadState* ets = it.first(); ets != NULL; ets = it.next(ets)) {
      JvmtiEnv *env = ets->get_env();
      if (env->phase() == JVMTI_PHASE_PRIMORDIAL) {
        continue;
      }
      if (ets->is_enabled(JVMTI_EVENT_VIRTUAL_THREAD_END)) {
        EVT_TRACE(JVMTI_EVENT_VIRTUAL_THREAD_END, ("[%p] Evt Virtual Thread End event sent", vthread));

        JvmtiVirtualThreadEventMark jem(cur_thread);
        JvmtiJavaThreadEventTransition jet(cur_thread);
        jvmtiEventVirtualThreadEnd callback = env->callbacks()->VirtualThreadEnd;
        if (callback != NULL) {
          (*callback)(env->jvmti_external(), jem.jni_env(), vthread);
        }
      }
    }
  }
}

void JvmtiExport::post_vthread_mount(jobject vthread) {
  if (JvmtiEnv::get_phase() < JVMTI_PHASE_PRIMORDIAL) {
    return;
  }
  JavaThread *thread = JavaThread::current();
  HandleMark hm(thread);
  EVT_TRIG_TRACE(EXT_EVENT_VIRTUAL_THREAD_MOUNT, ("[%p] Trg Virtual Thread Mount event triggered", vthread));

  JvmtiThreadState *state = thread->jvmti_thread_state();
  if (state == NULL) {
    return;
  }

  if (state->is_enabled((jvmtiEvent)EXT_EVENT_VIRTUAL_THREAD_MOUNT)) {
    JvmtiEnvThreadStateIterator it(state);

    for (JvmtiEnvThreadState* ets = it.first(); ets != NULL; ets = it.next(ets)) {
      JvmtiEnv *env = ets->get_env();
      if (env->phase() == JVMTI_PHASE_PRIMORDIAL) {
        continue;
      }
      if (ets->is_enabled((jvmtiEvent)EXT_EVENT_VIRTUAL_THREAD_MOUNT)) {
        EVT_TRACE(EXT_EVENT_VIRTUAL_THREAD_MOUNT, ("[%p] Evt Virtual Thread Mount event sent", vthread));

        JvmtiVirtualThreadEventMark jem(thread);
        JvmtiJavaThreadEventTransition jet(thread);
        jvmtiExtensionEvent callback = env->ext_callbacks()->VirtualThreadMount;
        if (callback != NULL) {
          (*callback)(env->jvmti_external(), jem.jni_env(), jem.jni_thread());
        }
      }
    }
  }
}

void JvmtiExport::post_vthread_unmount(jobject vthread) {
  if (JvmtiEnv::get_phase() < JVMTI_PHASE_PRIMORDIAL) {
    return;
  }
  JavaThread *thread = JavaThread::current();
  HandleMark hm(thread);
  EVT_TRIG_TRACE(EXT_EVENT_VIRTUAL_THREAD_UNMOUNT, ("[%p] Trg Virtual Thread Unmount event triggered", vthread));

  JvmtiThreadState *state = thread->jvmti_thread_state();
  if (state == NULL) {
    return;
  }

  if (state->is_enabled((jvmtiEvent)EXT_EVENT_VIRTUAL_THREAD_UNMOUNT)) {
    JvmtiEnvThreadStateIterator it(state);

    for (JvmtiEnvThreadState* ets = it.first(); ets != NULL; ets = it.next(ets)) {
      JvmtiEnv *env = ets->get_env();
      if (env->phase() == JVMTI_PHASE_PRIMORDIAL) {
        continue;
      }
      if (ets->is_enabled((jvmtiEvent)EXT_EVENT_VIRTUAL_THREAD_UNMOUNT)) {
        EVT_TRACE(EXT_EVENT_VIRTUAL_THREAD_UNMOUNT, ("[%p] Evt Virtual Thread Unmount event sent", vthread));

        JvmtiVirtualThreadEventMark jem(thread);
        JvmtiJavaThreadEventTransition jet(thread);
        jvmtiExtensionEvent callback = env->ext_callbacks()->VirtualThreadUnmount;
        if (callback != NULL) {
          (*callback)(env->jvmti_external(), jem.jni_env(), jem.jni_thread());
        }
      }
    }
  }
}

void JvmtiExport::continuation_yield_cleanup(JavaThread* thread, jint continuation_frame_count) {
  if (JvmtiEnv::get_phase() < JVMTI_PHASE_PRIMORDIAL) {
    return;
  }

  assert(thread == JavaThread::current(), "must be");
  JvmtiThreadState *state = thread->jvmti_thread_state();
  if (state == NULL) {
    return;
  }
  state->invalidate_cur_stack_depth();

  // Clear frame_pop requests in frames popped by yield
  if (can_post_frame_pop()) {
    JvmtiEnvThreadStateIterator it(state);
    int top_frame_num = state->cur_stack_depth() + continuation_frame_count;

    for (JvmtiEnvThreadState* ets = it.first(); ets != NULL; ets = it.next(ets)) {
      if (!ets->has_frame_pops()) {
        continue;
      }
      for (int frame_idx = 0; frame_idx < continuation_frame_count; frame_idx++) {
        int frame_num = top_frame_num - frame_idx;

        if (!state->is_virtual() && ets->is_frame_pop(frame_num)) {
          // remove the frame's entry
          MutexLocker mu(JvmtiThreadState_lock);
          ets->clear_frame_pop(frame_num);
        }
      }
    }
  }
}

void JvmtiExport::post_object_free(JvmtiEnv* env, GrowableArray<jlong>* objects) {
  assert(objects != NULL, "Nothing to post");

  JavaThread *javaThread = JavaThread::current();
  if (javaThread->is_in_any_VTMS_transition()) {
    return; // no events should be posted if thread is in any VTMS transition
  }
  if (!env->is_enabled(JVMTI_EVENT_OBJECT_FREE)) {
    return; // the event type has been already disabled
  }

  EVT_TRIG_TRACE(JVMTI_EVENT_OBJECT_FREE, ("[?] Trg Object Free triggered" ));
  EVT_TRACE(JVMTI_EVENT_OBJECT_FREE, ("[?] Evt Object Free sent"));

  JvmtiThreadEventMark jem(javaThread);
  JvmtiJavaThreadEventTransition jet(javaThread);
  jvmtiEventObjectFree callback = env->callbacks()->ObjectFree;
  if (callback != NULL) {
    for (int index = 0; index < objects->length(); index++) {
      (*callback)(env->jvmti_external(), objects->at(index));
    }
  }
}

void JvmtiExport::post_resource_exhausted(jint resource_exhausted_flags, const char* description) {

  JavaThread *thread  = JavaThread::current();

  if (thread->is_in_any_VTMS_transition()) {
    return; // no events should be posted if thread is in any VTMS transition
  }

  log_error(jvmti)("Posting Resource Exhausted event: %s",
                   description != nullptr ? description : "unknown");

  // JDK-8213834: handlers of ResourceExhausted may attempt some analysis
  // which often requires running java.
  // This will cause problems on threads not able to run java, e.g. compiler
  // threads. To forestall these problems, we therefore suppress sending this
  // event from threads which are not able to run java.
  if (!thread->can_call_java()) {
    return;
  }

  EVT_TRIG_TRACE(JVMTI_EVENT_RESOURCE_EXHAUSTED, ("Trg resource exhausted event triggered" ));

  JvmtiEnvIterator it;
  for (JvmtiEnv* env = it.first(); env != NULL; env = it.next(env)) {
    if (env->is_enabled(JVMTI_EVENT_RESOURCE_EXHAUSTED)) {
      EVT_TRACE(JVMTI_EVENT_RESOURCE_EXHAUSTED, ("Evt resource exhausted event sent" ));

      JvmtiThreadEventMark jem(thread);
      JvmtiJavaThreadEventTransition jet(thread);
      jvmtiEventResourceExhausted callback = env->callbacks()->ResourceExhausted;
      if (callback != NULL) {
        (*callback)(env->jvmti_external(), jem.jni_env(),
                    resource_exhausted_flags, NULL, description);
      }
    }
  }
}

void JvmtiExport::post_method_entry(JavaThread *thread, Method* method, frame current_frame) {
  HandleMark hm(thread);
  methodHandle mh(thread, method);

  JvmtiThreadState* state = thread->jvmti_thread_state();
  if (state == NULL || !state->is_interp_only_mode()) {
    // for any thread that actually wants method entry, interp_only_mode is set
    return;
  }
  if (mh->jvmti_mount_transition() || thread->is_in_any_VTMS_transition()) {
    return; // no events should be posted if thread is in any VTMS transition
  }
  EVT_TRIG_TRACE(JVMTI_EVENT_METHOD_ENTRY, ("[%s] Trg Method Entry triggered %s.%s",
                     JvmtiTrace::safe_get_thread_name(thread),
                     (mh() == NULL) ? "NULL" : mh()->klass_name()->as_C_string(),
                     (mh() == NULL) ? "NULL" : mh()->name()->as_C_string() ));

  state->incr_cur_stack_depth();

  if (state->is_enabled(JVMTI_EVENT_METHOD_ENTRY)) {
    JvmtiEnvThreadStateIterator it(state);
    for (JvmtiEnvThreadState* ets = it.first(); ets != NULL; ets = it.next(ets)) {
      if (ets->is_enabled(JVMTI_EVENT_METHOD_ENTRY)) {
        EVT_TRACE(JVMTI_EVENT_METHOD_ENTRY, ("[%s] Evt Method Entry sent %s.%s",
                                             JvmtiTrace::safe_get_thread_name(thread),
                                             (mh() == NULL) ? "NULL" : mh()->klass_name()->as_C_string(),
                                             (mh() == NULL) ? "NULL" : mh()->name()->as_C_string() ));

        JvmtiEnv *env = ets->get_env();
        JvmtiMethodEventMark jem(thread, mh);
        JvmtiJavaThreadEventTransition jet(thread);
        jvmtiEventMethodEntry callback = env->callbacks()->MethodEntry;
        if (callback != NULL) {
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