text: /* Copyright (C) 2017 The Android Open Source Project
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This file implements interfaces from the file jvmti.h. This implementation
   * is licensed under the same terms as the file jvmti.h.  The
   * copyright and license information for the file jvmti.h follows.
   *
   * Copyright (c) 2003, 2011, 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.  Oracle designates this
   * particular file as subject to the "Classpath" exception as provided
   * by Oracle in the LICENSE file that accompanied this code.
   *
   * 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 <functional>
  
  #include "deopt_manager.h"
  
  #include "art_jvmti.h"
  #include "art_method-inl.h"
  #include "base/enums.h"
  #include "base/mutex-inl.h"
  #include "dex/dex_file_annotations.h"
  #include "dex/modifiers.h"
  #include "events-inl.h"
  #include "jit/jit.h"
  #include "jni_internal.h"
  #include "mirror/class-inl.h"
  #include "mirror/object_array-inl.h"
  #include "nativehelper/scoped_local_ref.h"
  #include "runtime_callbacks.h"
  #include "scoped_thread_state_change-inl.h"
  #include "thread-current-inl.h"
  #include "thread_list.h"
  #include "ti_phase.h"
  
  namespace openjdkjvmti {
  
  // TODO We should make this much more selective in the future so we only return true when we
  // actually care about the method at this time (ie active frames had locals changed). For now we
  // just assume that if anything has changed any frame's locals we care about all methods. If nothing
  // has we only care about methods with active breakpoints on them. In the future we should probably
  // rewrite all of this to instead do this at the ShadowFrame or thread granularity.
  bool JvmtiMethodInspectionCallback::IsMethodBeingInspected(art::ArtMethod* method) {
    // Non-java-debuggable runtimes we need to assume that any method might not be debuggable and
    // therefore potentially being inspected (due to inlines). If we are debuggable we rely hard on
    // inlining not being done since we don't keep track of which methods get inlined where and simply
    // look to see if the method is breakpointed.
    return !art::Runtime::Current()->IsJavaDebuggable() ||
        manager_->HaveLocalsChanged() ||
        manager_->MethodHasBreakpoints(method);
  }
  
  bool JvmtiMethodInspectionCallback::IsMethodSafeToJit(art::ArtMethod* method) {
    return !manager_->MethodHasBreakpoints(method);
  }
  
  bool JvmtiMethodInspectionCallback::MethodNeedsDebugVersion(
      art::ArtMethod* method ATTRIBUTE_UNUSED) {
    return true;
  }
  
  DeoptManager::DeoptManager()
    : deoptimization_status_lock_("JVMTI_DeoptimizationStatusLock",
                                  static_cast<art::LockLevel>(
                                      art::LockLevel::kClassLinkerClassesLock + 1)),
      deoptimization_condition_("JVMTI_DeoptimizationCondition", deoptimization_status_lock_),
      performing_deoptimization_(false),
      global_deopt_count_(0),
      deopter_count_(0),
      breakpoint_status_lock_("JVMTI_BreakpointStatusLock",
                              static_cast<art::LockLevel>(art::LockLevel::kAbortLock + 1)),
      inspection_callback_(this),
      set_local_variable_called_(false) { }
  
  void DeoptManager::Setup() {
    art::ScopedThreadStateChange stsc(art::Thread::Current(),
                                      art::ThreadState::kWaitingForDebuggerToAttach);
    art::ScopedSuspendAll ssa("Add method Inspection Callback");
    art::RuntimeCallbacks* callbacks = art::Runtime::Current()->GetRuntimeCallbacks();
    callbacks->AddMethodInspectionCallback(&inspection_callback_);
  }
  
  void DeoptManager::Shutdown() {
    art::ScopedThreadStateChange stsc(art::Thread::Current(),
                                      art::ThreadState::kWaitingForDebuggerToAttach);
    art::ScopedSuspendAll ssa("remove method Inspection Callback");
    art::RuntimeCallbacks* callbacks = art::Runtime::Current()->GetRuntimeCallbacks();
    callbacks->RemoveMethodInspectionCallback(&inspection_callback_);
  }
  
  void DeoptManager::FinishSetup() {
    art::Thread* self = art::Thread::Current();
    art::MutexLock mu(self, deoptimization_status_lock_);
  
    art::Runtime* runtime = art::Runtime::Current();
    // See if we need to do anything.
    if (!runtime->IsJavaDebuggable()) {
      // See if we can enable all JVMTI functions. If this is false, only kArtTiVersion agents can be
      // retrieved and they will all be best-effort.
      if (PhaseUtil::GetPhaseUnchecked() == JVMTI_PHASE_ONLOAD) {
        // We are still early enough to change the compiler options and get full JVMTI support.
        LOG(INFO) << "Openjdkjvmti plugin loaded on a non-debuggable runtime. Changing runtime to "
                  << "debuggable state. Please pass '--debuggable' to dex2oat and "
                  << "'-Xcompiler-option --debuggable' to dalvikvm in the future.";
        DCHECK(runtime->GetJit() == nullptr) << "Jit should not be running yet!";
        runtime->AddCompilerOption("--debuggable");
        runtime->SetJavaDebuggable(true);
      } else {
        LOG(WARNING) << "Openjdkjvmti plugin was loaded on a non-debuggable Runtime. Plugin was "
                     << "loaded too late to change runtime state to DEBUGGABLE. Only kArtTiVersion "
                     << "(0x" << std::hex << kArtTiVersion << ") environments are available. Some "
                     << "functionality might not work properly.";
        if (runtime->GetJit() == nullptr &&
            runtime->GetJITOptions()->UseJitCompilation() &&
            !runtime->GetInstrumentation()->IsForcedInterpretOnly()) {
          // If we don't have a jit we should try to start the jit for performance reasons. We only
          // need to do this for late attach on non-debuggable processes because for debuggable
          // processes we already rely on jit and we cannot force this jit to start if we are still in
          // OnLoad since the runtime hasn't started up sufficiently. This is only expected to happen
          // on userdebug/eng builds.
          LOG(INFO) << "Attempting to start jit for openjdkjvmti plugin.";
          runtime->CreateJit();
          if (runtime->GetJit() == nullptr) {
            LOG(WARNING) << "Could not start jit for openjdkjvmti plugin. This process might be "
                         << "quite slow as it is running entirely in the interpreter. Try running "
                         << "'setenforce 0' and restarting this process.";
          }
        }
      }
      runtime->DeoptimizeBootImage();
    }
  }
  
  bool DeoptManager::MethodHasBreakpoints(art::ArtMethod* method) {
    art::MutexLock lk(art::Thread::Current(), breakpoint_status_lock_);
    return MethodHasBreakpointsLocked(method);
  }
  
  bool DeoptManager::MethodHasBreakpointsLocked(art::ArtMethod* method) {
    auto elem = breakpoint_status_.find(method);
    return elem != breakpoint_status_.end() && elem->second != 0;
  }
  
  void DeoptManager::RemoveDeoptimizeAllMethods() {
    art::Thread* self = art::Thread::Current();
    art::ScopedThreadSuspension sts(self, art::kSuspended);
    deoptimization_status_lock_.ExclusiveLock(self);
    RemoveDeoptimizeAllMethodsLocked(self);
  }
  
  void DeoptManager::AddDeoptimizeAllMethods() {
    art::Thread* self = art::Thread::Current();
    art::ScopedThreadSuspension sts(self, art::kSuspended);
    deoptimization_status_lock_.ExclusiveLock(self);
    AddDeoptimizeAllMethodsLocked(self);
  }
  
  void DeoptManager::AddMethodBreakpoint(art::ArtMethod* method) {
    DCHECK(method->IsInvokable());
    DCHECK(!method->IsProxyMethod()) << method->PrettyMethod();
    DCHECK(!method->IsNative()) << method->PrettyMethod();
  
    art::Thread* self = art::Thread::Current();
    method = method->GetCanonicalMethod();
    bool is_default = method->IsDefault();
  
    art::ScopedThreadSuspension sts(self, art::kSuspended);
    deoptimization_status_lock_.ExclusiveLock(self);
    {
      breakpoint_status_lock_.ExclusiveLock(self);
  
      DCHECK_GT(deopter_count_, 0u) << "unexpected deotpimization request";
  
      if (MethodHasBreakpointsLocked(method)) {
        // Don't need to do anything extra.
        breakpoint_status_[method]++;
        // Another thread might be deoptimizing the very method we just added new breakpoints for.
        // Wait for any deopts to finish before moving on.
        breakpoint_status_lock_.ExclusiveUnlock(self);
        WaitForDeoptimizationToFinish(self);
        return;
      }
      breakpoint_status_[method] = 1;
      breakpoint_status_lock_.ExclusiveUnlock(self);
    }
    auto instrumentation = art::Runtime::Current()->GetInstrumentation();
    if (instrumentation->IsForcedInterpretOnly()) {
      // We are already interpreting everything so no need to do anything.
      deoptimization_status_lock_.ExclusiveUnlock(self);
      return;
    } else if (is_default) {
      AddDeoptimizeAllMethodsLocked(self);
    } else {
      PerformLimitedDeoptimization(self, method);
    }
  }
  
  void DeoptManager::RemoveMethodBreakpoint(art::ArtMethod* method) {
    DCHECK(method->IsInvokable()) << method->PrettyMethod();
    DCHECK(!method->IsProxyMethod()) << method->PrettyMethod();
    DCHECK(!method->IsNative()) << method->PrettyMethod();
  
    art::Thread* self = art::Thread::Current();
    method = method->GetCanonicalMethod();
    bool is_default = method->IsDefault();
  
    art::ScopedThreadSuspension sts(self, art::kSuspended);
    // Ideally we should do a ScopedSuspendAll right here to get the full mutator_lock_ that we might
    // need but since that is very heavy we will instead just use a condition variable to make sure we
    // don't race with ourselves.
    deoptimization_status_lock_.ExclusiveLock(self);
    bool is_last_breakpoint;
    {
      art::MutexLock mu(self, breakpoint_status_lock_);
  
      DCHECK_GT(deopter_count_, 0u) << "unexpected deotpimization request";
      DCHECK(MethodHasBreakpointsLocked(method)) << "Breakpoint on a method was removed without "
                                                << "breakpoints present!";
      breakpoint_status_[method] -= 1;
      is_last_breakpoint = (breakpoint_status_[method] == 0);
    }
    auto instrumentation = art::Runtime::Current()->GetInstrumentation();
    if (UNLIKELY(instrumentation->IsForcedInterpretOnly())) {
      // We don't need to do anything since we are interpreting everything anyway.
      deoptimization_status_lock_.ExclusiveUnlock(self);
      return;
    } else if (is_last_breakpoint) {
      if (UNLIKELY(is_default)) {
        RemoveDeoptimizeAllMethodsLocked(self);
      } else {
        PerformLimitedUndeoptimization(self, method);
      }
    } else {
      // Another thread might be deoptimizing the very methods we just removed breakpoints from. Wait
      // for any deopts to finish before moving on.
      WaitForDeoptimizationToFinish(self);
    }
  }
  
  void DeoptManager::WaitForDeoptimizationToFinishLocked(art::Thread* self) {
    while (performing_deoptimization_) {
      deoptimization_condition_.Wait(self);
    }
  }
  
  void DeoptManager::WaitForDeoptimizationToFinish(art::Thread* self) {
    WaitForDeoptimizationToFinishLocked(self);
    deoptimization_status_lock_.ExclusiveUnlock(self);
  }
  
  class ScopedDeoptimizationContext : public art::ValueObject {
   public:
    ScopedDeoptimizationContext(art::Thread* self, DeoptManager* deopt)
        RELEASE(deopt->deoptimization_status_lock_)
        ACQUIRE(art::Locks::mutator_lock_)
        ACQUIRE(art::Roles::uninterruptible_)
        : self_(self), deopt_(deopt), uninterruptible_cause_(nullptr) {
      deopt_->WaitForDeoptimizationToFinishLocked(self_);
      DCHECK(!deopt->performing_deoptimization_)
          << "Already performing deoptimization on another thread!";
      // Use performing_deoptimization_ to keep track of the lock.
      deopt_->performing_deoptimization_ = true;
      deopt_->deoptimization_status_lock_.Unlock(self_);
      art::Runtime::Current()->GetThreadList()->SuspendAll("JMVTI Deoptimizing methods",
                                                           /*long_suspend*/ false);
      uninterruptible_cause_ = self_->StartAssertNoThreadSuspension("JVMTI deoptimizing methods");
    }
  
    ~ScopedDeoptimizationContext()
        RELEASE(art::Locks::mutator_lock_)
        RELEASE(art::Roles::uninterruptible_) {
      // Can be suspended again.
      self_->EndAssertNoThreadSuspension(uninterruptible_cause_);
      // Release the mutator lock.
      art::Runtime::Current()->GetThreadList()->ResumeAll();
      // Let other threads know it's fine to proceed.
      art::MutexLock lk(self_, deopt_->deoptimization_status_lock_);
      deopt_->performing_deoptimization_ = false;
      deopt_->deoptimization_condition_.Broadcast(self_);
    }
  
   private:
    art::Thread* self_;
    DeoptManager* deopt_;
    const char* uninterruptible_cause_;
  };
  
  void DeoptManager::AddDeoptimizeAllMethodsLocked(art::Thread* self) {
    global_deopt_count_++;
    if (global_deopt_count_ == 1) {
      PerformGlobalDeoptimization(self);
    } else {
      WaitForDeoptimizationToFinish(self);
    }
  }
  
  void DeoptManager::RemoveDeoptimizeAllMethodsLocked(art::Thread* self) {
    DCHECK_GT(global_deopt_count_, 0u) << "Request to remove non-existent global deoptimization!";
    global_deopt_count_--;
    if (global_deopt_count_ == 0) {
      PerformGlobalUndeoptimization(self);
    } else {
      WaitForDeoptimizationToFinish(self);
    }
  }
  
  void DeoptManager::PerformLimitedDeoptimization(art::Thread* self, art::ArtMethod* method) {
    ScopedDeoptimizationContext sdc(self, this);
    art::Runtime::Current()->GetInstrumentation()->Deoptimize(method);
  }
  
  void DeoptManager::PerformLimitedUndeoptimization(art::Thread* self, art::ArtMethod* method) {
    ScopedDeoptimizationContext sdc(self, this);
    art::Runtime::Current()->GetInstrumentation()->Undeoptimize(method);
  }
  
  void DeoptManager::PerformGlobalDeoptimization(art::Thread* self) {
    ScopedDeoptimizationContext sdc(self, this);
    art::Runtime::Current()->GetInstrumentation()->DeoptimizeEverything(
        kDeoptManagerInstrumentationKey);
  }
  
  void DeoptManager::PerformGlobalUndeoptimization(art::Thread* self) {
    ScopedDeoptimizationContext sdc(self, this);
    art::Runtime::Current()->GetInstrumentation()->UndeoptimizeEverything(
        kDeoptManagerInstrumentationKey);
  }
  
  
  void DeoptManager::RemoveDeoptimizationRequester() {
    art::Thread* self = art::Thread::Current();
    art::ScopedThreadStateChange sts(self, art::kSuspended);
    deoptimization_status_lock_.ExclusiveLock(self);
    DCHECK_GT(deopter_count_, 0u) << "Removing deoptimization requester without any being present";
    deopter_count_--;
    if (deopter_count_ == 0) {
      ScopedDeoptimizationContext sdc(self, this);
      // TODO Give this a real key.
      art::Runtime::Current()->GetInstrumentation()->DisableDeoptimization("");
      return;
    } else {
      deoptimization_status_lock_.ExclusiveUnlock(self);
    }
  }
  
  void DeoptManager::AddDeoptimizationRequester() {
    art::Thread* self = art::Thread::Current();
    art::ScopedThreadStateChange stsc(self, art::kSuspended);
    deoptimization_status_lock_.ExclusiveLock(self);
    deopter_count_++;
    if (deopter_count_ == 1) {
      ScopedDeoptimizationContext sdc(self, this);
      art::Runtime::Current()->GetInstrumentation()->EnableDeoptimization();
      return;
    } else {
      deoptimization_status_lock_.ExclusiveUnlock(self);
    }
  }
  
  void DeoptManager::DeoptimizeThread(art::Thread* target) {
    art::Runtime::Current()->GetInstrumentation()->InstrumentThreadStack(target);
  }
  
  extern DeoptManager* gDeoptManager;
  DeoptManager* DeoptManager::Get() {
    return gDeoptManager;
  }
  
  }  // namespace openjdkjvmti
  