/*

 * Copyright (c) 1997, 2017, 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 "gc/shared/gcLocker.hpp"

#include "runtime/handles.inline.hpp"

#include "runtime/mutexLocker.hpp"

#include "runtime/orderAccess.hpp"

#include "runtime/os.hpp"

#include "runtime/safepointMechanism.inline.hpp"

#include "utilities/globalDefinitions.hpp"

#include "utilities/macros.hpp"

#include "utilities/preserveException.hpp"

// Wrapper for all entry points to the virtual machine.

// InterfaceSupport provides functionality used by the VM_LEAF_BASE and

// VM_ENTRY_BASE macros. These macros are used to guard entry points into

// the VM and perform checks upon leave of the VM.

class InterfaceSupport: AllStatic {

# ifdef ASSERT

 public:

  static long _scavenge_alot_counter;

  static long _fullgc_alot_counter;

  static long _number_of_calls;

  static long _fullgc_alot_invocation;

  // Helper methods used to implement +ScavengeALot and +FullGCALot

  static void check_gc_alot() { if (ScavengeALot || FullGCALot) gc_alot(); }

  static void gc_alot();

  static void walk_stack_from(vframe* start_vf);

  static void walk_stack();

  static void zombieAll();

  static void unlinkSymbols();

  static void deoptimizeAll();

  static void stress_derived_pointers();

  static void verify_stack();

  static void verify_last_frame();

# endif

 public:

  static void serialize_thread_state_with_handler(JavaThread* thread) {

    serialize_thread_state_internal(thread, true);

  }

  // Should only call this if we know that we have a proper SEH set up.

  static void serialize_thread_state(JavaThread* thread) {

    serialize_thread_state_internal(thread, false);

  }

 private:

  static void serialize_thread_state_internal(JavaThread* thread, bool needs_exception_handler) {

    // Make sure new state is seen by VM thread

    if (os::is_MP()) {

      if (UseMembar) {

        // Force a fence between the write above and read below

        OrderAccess::fence();

      } else {

        // store to serialize page so VM thread can do pseudo remote membar

        if (needs_exception_handler) {

          os::write_memory_serialize_page_with_handler(thread);

        } else {

          os::write_memory_serialize_page(thread);

        }

      }

    }

  }

};

// Basic class for all thread transition classes.

class ThreadStateTransition : public StackObj {

 protected:

  JavaThread* _thread;

 public:

  ThreadStateTransition(JavaThread *thread) {

    _thread = thread;

    assert(thread != NULL && thread->is_Java_thread(), "must be Java thread");

  }

  // Change threadstate in a manner, so safepoint can detect changes.

  // Time-critical: called on exit from every runtime routine

  static inline void transition(JavaThread *thread, JavaThreadState from, JavaThreadState to) {

    assert(from != _thread_in_Java, "use transition_from_java");

    assert(from != _thread_in_native, "use transition_from_native");

    assert((from & 1) == 0 && (to & 1) == 0, "odd numbers are transitions states");

    assert(thread->thread_state() == from, "coming from wrong thread state");

    // Change to transition state

    thread->set_thread_state((JavaThreadState)(from + 1));

    InterfaceSupport::serialize_thread_state(thread);

    SafepointMechanism::block_if_requested(thread);

    thread->set_thread_state(to);

    CHECK_UNHANDLED_OOPS_ONLY(thread->clear_unhandled_oops();)

  }

  // transition_and_fence must be used on any thread state transition

  // where there might not be a Java call stub on the stack, in

  // particular on Windows where the Structured Exception Handler is

  // set up in the call stub. os::write_memory_serialize_page() can

  // fault and we can't recover from it on Windows without a SEH in

  // place.

  static inline void transition_and_fence(JavaThread *thread, JavaThreadState from, JavaThreadState to) {

    assert(thread->thread_state() == from, "coming from wrong thread state");

    assert((from & 1) == 0 && (to & 1) == 0, "odd numbers are transitions states");

    // Change to transition state

    thread->set_thread_state((JavaThreadState)(from + 1));

    InterfaceSupport::serialize_thread_state_with_handler(thread);

    SafepointMechanism::block_if_requested(thread);

    thread->set_thread_state(to);

    CHECK_UNHANDLED_OOPS_ONLY(thread->clear_unhandled_oops();)

  }

  // Same as above, but assumes from = _thread_in_Java. This is simpler, since we

  // never block on entry to the VM. This will break the code, since e.g. preserve arguments

  // have not been setup.

  static inline void transition_from_java(JavaThread *thread, JavaThreadState to) {

    assert(thread->thread_state() == _thread_in_Java, "coming from wrong thread state");

    thread->set_thread_state(to);

  }

  static inline void transition_from_native(JavaThread *thread, JavaThreadState to) {

    assert((to & 1) == 0, "odd numbers are transitions states");

    assert(thread->thread_state() == _thread_in_native, "coming from wrong thread state");

    // Change to transition state

    thread->set_thread_state(_thread_in_native_trans);

    InterfaceSupport::serialize_thread_state_with_handler(thread);

    // We never install asynchronous exceptions when coming (back) in

    // to the runtime from native code because the runtime is not set

    // up to handle exceptions floating around at arbitrary points.

    if (SafepointMechanism::poll(thread) || thread->is_suspend_after_native()) {

      JavaThread::check_safepoint_and_suspend_for_native_trans(thread);

      // Clear unhandled oops anywhere where we could block, even if we don't.

      CHECK_UNHANDLED_OOPS_ONLY(thread->clear_unhandled_oops();)

    }

    thread->set_thread_state(to);

  }

 protected:

   void trans(JavaThreadState from, JavaThreadState to)  { transition(_thread, from, to); }

   void trans_from_java(JavaThreadState to)              { transition_from_java(_thread, to); }

   void trans_from_native(JavaThreadState to)            { transition_from_native(_thread, to); }

   void trans_and_fence(JavaThreadState from, JavaThreadState to) { transition_and_fence(_thread, from, to); }

};

class ThreadInVMForHandshake : public ThreadStateTransition {

  const JavaThreadState _original_state;

  void transition_back() {

    // This can be invoked from transition states and must return to the original state properly

    assert(_thread->thread_state() == _thread_in_vm, "should only call when leaving VM after handshake");

    _thread->set_thread_state(_thread_in_vm_trans);

    InterfaceSupport::serialize_thread_state(_thread);

    SafepointMechanism::block_if_requested(_thread);

    _thread->set_thread_state(_original_state);

  }

 public:

  ThreadInVMForHandshake(JavaThread* thread) : ThreadStateTransition(thread),

      _original_state(thread->thread_state()) {

    if (thread->has_last_Java_frame()) {

      thread->frame_anchor()->make_walkable(thread);

    }

    thread->set_thread_state(_thread_in_vm);

  }

  ~ThreadInVMForHandshake() {

    transition_back();

  }

};

class ThreadInVMfromJava : public ThreadStateTransition {

 public:

  ThreadInVMfromJava(JavaThread* thread) : ThreadStateTransition(thread) {

    trans_from_java(_thread_in_vm);

  }

  ~ThreadInVMfromJava()  {

    if (_thread->stack_yellow_reserved_zone_disabled()) {

      _thread->enable_stack_yellow_reserved_zone();

    }

    trans(_thread_in_vm, _thread_in_Java);

    // Check for pending. async. exceptions or suspends.

    if (_thread->has_special_runtime_exit_condition()) _thread->handle_special_runtime_exit_condition();

  }

};

class ThreadInVMfromUnknown {

 private:

  JavaThread* _thread;

 public:

  ThreadInVMfromUnknown() : _thread(NULL) {

    Thread* t = Thread::current();

    if (t->is_Java_thread()) {

      JavaThread* t2 = (JavaThread*) t;

      if (t2->thread_state() == _thread_in_native) {

        _thread = t2;

        ThreadStateTransition::transition_from_native(t2, _thread_in_vm);

        // Used to have a HandleMarkCleaner but that is dangerous as

        // it could free a handle in our (indirect, nested) caller.

        // We expect any handles will be short lived and figure we

        // don't need an actual HandleMark.

      }

    }

  }

  ~ThreadInVMfromUnknown()  {

    if (_thread) {

      ThreadStateTransition::transition_and_fence(_thread, _thread_in_vm, _thread_in_native);

    }

  }

};

class ThreadInVMfromNative : public ThreadStateTransition {

 public:

  ThreadInVMfromNative(JavaThread* thread) : ThreadStateTransition(thread) {

    trans_from_native(_thread_in_vm);

  }

  ~ThreadInVMfromNative() {

    trans_and_fence(_thread_in_vm, _thread_in_native);

  }

};

class ThreadToNativeFromVM : public ThreadStateTransition {

 public:

  ThreadToNativeFromVM(JavaThread *thread) : ThreadStateTransition(thread) {

    // We are leaving the VM at this point and going directly to native code.

    // Block, if we are in the middle of a safepoint synchronization.

    assert(!thread->owns_locks(), "must release all locks when leaving VM");

    thread->frame_anchor()->make_walkable(thread);

    trans_and_fence(_thread_in_vm, _thread_in_native);

    // Check for pending. async. exceptions or suspends.

    if (_thread->has_special_runtime_exit_condition()) _thread->handle_special_runtime_exit_condition(false);

  }

  ~ThreadToNativeFromVM() {

    trans_from_native(_thread_in_vm);

    assert(!_thread->is_pending_jni_exception_check(), "Pending JNI Exception Check");

    // We don't need to clear_walkable because it will happen automagically when we return to java

  }

};

class ThreadBlockInVM : public ThreadStateTransition {

 public:

  ThreadBlockInVM(JavaThread *thread)

  : ThreadStateTransition(thread) {

    // Once we are blocked vm expects stack to be walkable

    thread->frame_anchor()->make_walkable(thread);

    trans_and_fence(_thread_in_vm, _thread_blocked);

  }

  ~ThreadBlockInVM() {

    trans_and_fence(_thread_blocked, _thread_in_vm);

    // We don't need to clear_walkable because it will happen automagically when we return to java

  }

};

// This special transition class is only used to prevent asynchronous exceptions

// from being installed on vm exit in situations where we can't tolerate them.

// See bugs: 4324348, 4854693, 4998314, 5040492, 5050705.

class ThreadInVMfromJavaNoAsyncException : public ThreadStateTransition {

 public:

  ThreadInVMfromJavaNoAsyncException(JavaThread* thread) : ThreadStateTransition(thread) {

    trans_from_java(_thread_in_vm);

  }

  ~ThreadInVMfromJavaNoAsyncException()  {

    if (_thread->stack_yellow_reserved_zone_disabled()) {

      _thread->enable_stack_yellow_reserved_zone();

    }

    trans(_thread_in_vm, _thread_in_Java);

    // NOTE: We do not check for pending. async. exceptions.

    // If we did and moved the pending async exception over into the

    // pending exception field, we would need to deopt (currently C2

    // only). However, to do so would require that we transition back

    // to the _thread_in_vm state. Instead we postpone the handling of

    // the async exception.

    // Check for pending. suspends only.

    if (_thread->has_special_runtime_exit_condition())

      _thread->handle_special_runtime_exit_condition(false);

  }

};

// Debug class instantiated in JRT_ENTRY and ITR_ENTRY macro.

// Can be used to verify properties on enter/exit of the VM.

#ifdef ASSERT

class VMEntryWrapper {

 public:

};

class VMNativeEntryWrapper {

 public:

  VMNativeEntryWrapper() {

    if (GCALotAtAllSafepoints) InterfaceSupport::check_gc_alot();

  }

  ~VMNativeEntryWrapper() {

    if (GCALotAtAllSafepoints) InterfaceSupport::check_gc_alot();

  }

};

#endif

// VM-internal runtime interface support

#ifdef ASSERT

class RuntimeHistogramElement : public HistogramElement {

  public:

   RuntimeHistogramElement(const char* name);

};

#define TRACE_CALL(result_type, header)                            \

  InterfaceSupport::_number_of_calls++;                            \

  if (CountRuntimeCalls) {                                         \

    static RuntimeHistogramElement* e = new RuntimeHistogramElement(#header); \

    if (e != NULL) e->increment_count();                           \

  }

#else

#define TRACE_CALL(result_type, header)                            \

  /* do nothing */

#endif

// LEAF routines do not lock, GC or throw exceptions

#define VM_LEAF_BASE(result_type, header)                            \

  TRACE_CALL(result_type, header)                                    \

  debug_only(NoHandleMark __hm;)                                     \

  os::verify_stack_alignment();                                      \

  /* begin of body */

#define VM_ENTRY_BASE_FROM_LEAF(result_type, header, thread)         \

  TRACE_CALL(result_type, header)                                    \

  debug_only(ResetNoHandleMark __rnhm;)                              \

  HandleMarkCleaner __hm(thread);                                    \

  Thread* THREAD = thread;                                           \

  os::verify_stack_alignment();                                      \

  /* begin of body */

// ENTRY routines may lock, GC and throw exceptions

#define VM_ENTRY_BASE(result_type, header, thread)                   \

  TRACE_CALL(result_type, header)                                    \

  HandleMarkCleaner __hm(thread);                                    \

  Thread* THREAD = thread;                                           \

  os::verify_stack_alignment();                                      \

  /* begin of body */

// QUICK_ENTRY routines behave like ENTRY but without a handle mark

#define VM_QUICK_ENTRY_BASE(result_type, header, thread)             \

  TRACE_CALL(result_type, header)                                    \

  debug_only(NoHandleMark __hm;)                                     \

  Thread* THREAD = thread;                                           \

  os::verify_stack_alignment();                                      \

  /* begin of body */

// Definitions for IRT (Interpreter Runtime)

// (thread is an argument passed in to all these routines)

#define IRT_ENTRY(result_type, header)                               \

  result_type header {                                               \

    ThreadInVMfromJava __tiv(thread);                                \

    VM_ENTRY_BASE(result_type, header, thread)                       \

    debug_only(VMEntryWrapper __vew;)

#define IRT_LEAF(result_type, header)                                \

  result_type header {                                               \

    VM_LEAF_BASE(result_type, header)                                \

    debug_only(NoSafepointVerifier __nspv(true);)

#define IRT_ENTRY_NO_ASYNC(result_type, header)                      \

  result_type header {                                               \

    ThreadInVMfromJavaNoAsyncException __tiv(thread);                \

    VM_ENTRY_BASE(result_type, header, thread)                       \

    debug_only(VMEntryWrapper __vew;)

#define IRT_END }

// Definitions for JRT (Java (Compiler/Shared) Runtime)

#define JRT_ENTRY(result_type, header)                               \

  result_type header {                                               \

    ThreadInVMfromJava __tiv(thread);                                \

    VM_ENTRY_BASE(result_type, header, thread)                       \

    debug_only(VMEntryWrapper __vew;)

#define JRT_LEAF(result_type, header)                                \

  result_type header {                                               \

  VM_LEAF_BASE(result_type, header)                                  \

  debug_only(JRTLeafVerifier __jlv;)

#define JRT_ENTRY_NO_ASYNC(result_type, header)                      \

  result_type header {                                               \

    ThreadInVMfromJavaNoAsyncException __tiv(thread);                \

    VM_ENTRY_BASE(result_type, header, thread)                       \

    debug_only(VMEntryWrapper __vew;)

// Same as JRT Entry but allows for return value after the safepoint

// to get back into Java from the VM

#define JRT_BLOCK_ENTRY(result_type, header)                         \

  result_type header {                                               \

    TRACE_CALL(result_type, header)                                  \

    HandleMarkCleaner __hm(thread);

#define JRT_BLOCK                                                    \

    {                                                                \

    ThreadInVMfromJava __tiv(thread);                                \

    Thread* THREAD = thread;                                         \

    debug_only(VMEntryWrapper __vew;)

#define JRT_BLOCK_NO_ASYNC                                           \

    {                                                                \

    ThreadInVMfromJavaNoAsyncException __tiv(thread);                \

    Thread* THREAD = thread;                                         \

    debug_only(VMEntryWrapper __vew;)

#define JRT_BLOCK_END }

#define JRT_END }

// Definitions for JNI

#define JNI_ENTRY(result_type, header)                               \

    JNI_ENTRY_NO_PRESERVE(result_type, header)                       \

    WeakPreserveExceptionMark __wem(thread);

#define JNI_ENTRY_NO_PRESERVE(result_type, header)                   \

extern "C" {                                                         \

  result_type JNICALL header {                                       \

    JavaThread* thread=JavaThread::thread_from_jni_environment(env); \

    assert( !VerifyJNIEnvThread || (thread == Thread::current()), "JNIEnv is only valid in same thread"); \

    ThreadInVMfromNative __tiv(thread);                              \

    debug_only(VMNativeEntryWrapper __vew;)                          \

    VM_ENTRY_BASE(result_type, header, thread)

// Ensure that the VMNativeEntryWrapper constructor, which can cause

// a GC, is called outside the NoHandleMark (set via VM_QUICK_ENTRY_BASE).

#define JNI_QUICK_ENTRY(result_type, header)                         \

extern "C" {                                                         \

  result_type JNICALL header {                                       \

    JavaThread* thread=JavaThread::thread_from_jni_environment(env); \

    assert( !VerifyJNIEnvThread || (thread == Thread::current()), "JNIEnv is only valid in same thread"); \

    ThreadInVMfromNative __tiv(thread);                              \

    debug_only(VMNativeEntryWrapper __vew;)                          \

    VM_QUICK_ENTRY_BASE(result_type, header, thread)

#define JNI_LEAF(result_type, header)                                \

extern "C" {                                                         \