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/* 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 <iosfwd>
#include <mutex>
#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 "gc/collector_type.h"
#include "gc/heap.h"
#include "gc/scoped_gc_critical_section.h"
#include "instrumentation.h"
#include "jit/jit.h"
#include "jni/jni_internal.h"
#include "mirror/class-inl.h"
#include "mirror/object_array-inl.h"
#include "nativehelper/scoped_local_ref.h"
#include "read_barrier_config.h"
#include "runtime_callbacks.h"
#include "scoped_thread_state_change-inl.h"
#include "scoped_thread_state_change.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::DumpDeoptInfo(art::Thread* self, std::ostream& stream) {
art::ScopedObjectAccess soa(self);
art::MutexLock mutll(self, *art::Locks::thread_list_lock_);
art::MutexLock mudsl(self, deoptimization_status_lock_);
art::MutexLock mubsl(self, breakpoint_status_lock_);
stream << "Deoptimizer count: " << deopter_count_ << "\n";
stream << "Global deopt count: " << global_deopt_count_ << "\n";
stream << "Can perform OSR: " << !set_local_variable_called_.load() << "\n";
for (const auto& [bp, loc] : this->breakpoint_status_) {
stream << "Breakpoint: " << bp->PrettyMethod() << " @ 0x" << std::hex << loc << "\n";
}
struct DumpThreadDeoptCount : public art::Closure {
public:
DumpThreadDeoptCount(std::ostream& stream, std::mutex& mu)
: cnt_(0), stream_(stream), mu_(mu) {}
void Run(art::Thread* self) override {
{
std::lock_guard<std::mutex> lg(mu_);
std::string name;
self->GetThreadName(name);
stream_ << "Thread " << name << " (id: " << std::dec << self->GetThreadId()
<< ") force interpreter count " << self->ForceInterpreterCount() << "\n";
}
// Increment this after unlocking the mutex so we won't race its destructor.
cnt_++;
}
void WaitForCount(size_t threads) {
while (cnt_.load() != threads) {
sched_yield();
}
}
private:
std::atomic<size_t> cnt_;
std::ostream& stream_;
std::mutex& mu_;
};
std::mutex mu;
DumpThreadDeoptCount dtdc(stream, mu);
auto func = [](art::Thread* thread, void* ctx) {
reinterpret_cast<DumpThreadDeoptCount*>(ctx)->Run(thread);
};
art::Runtime::Current()->GetThreadList()->ForEach(func, &dtdc);
}
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.";
// Note: use rwx allowed = true, because if this is the system server, we will not be
// allowed to allocate any JIT code cache, anyways.
runtime->CreateJitCodeCache(/*rwx_memory_allowed=*/true);
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::ThreadState::kSuspended);
deoptimization_status_lock_.ExclusiveLock(self);
RemoveDeoptimizeAllMethodsLocked(self);
}
void DeoptManager::AddDeoptimizeAllMethods() {
art::Thread* self = art::Thread::Current();
art::ScopedThreadSuspension sts(self, art::ThreadState::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::ThreadState::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::ThreadState::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);
}
// Users should make sure that only gc-critical-section safe code is used while a
// ScopedDeoptimizationContext exists.
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),
critical_section_(self_, "JVMTI Deoptimizing methods"),
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_);
uninterruptible_cause_ = critical_section_.Enter(art::gc::kGcCauseInstrumentation,
art::gc::kCollectorTypeCriticalSection);
art::Runtime::Current()->GetThreadList()->SuspendAll("JMVTI Deoptimizing methods",
/*long_suspend=*/ false);
}
~ScopedDeoptimizationContext()
RELEASE(art::Locks::mutator_lock_)
RELEASE(art::Roles::uninterruptible_) {
// Can be suspended again.
critical_section_.Exit(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_;
art::gc::GCCriticalSection critical_section_;
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);
}
jvmtiError DeoptManager::AddDeoptimizeThreadMethods(art::ScopedObjectAccessUnchecked& soa, jthread jtarget) {
art::Locks::thread_list_lock_->ExclusiveLock(soa.Self());
art::Thread* target = nullptr;
jvmtiError err = OK;
if (!ThreadUtil::GetNativeThread(jtarget, soa, &target, &err)) {
art::Locks::thread_list_lock_->ExclusiveUnlock(soa.Self());
return err;
}
// We don't need additional locking here because we hold the Thread_list_lock_.
if (target->IncrementForceInterpreterCount() == 1) {
struct DeoptClosure : public art::Closure {
public:
explicit DeoptClosure(DeoptManager* manager) : manager_(manager) {}
void Run(art::Thread* self) override REQUIRES_SHARED(art::Locks::mutator_lock_) {
manager_->DeoptimizeThread(self);
}
private:
DeoptManager* manager_;
};
DeoptClosure c(this);
target->RequestSynchronousCheckpoint(&c);
} else {
art::Locks::thread_list_lock_->ExclusiveUnlock(soa.Self());
}
return OK;
}
jvmtiError DeoptManager::RemoveDeoptimizeThreadMethods(art::ScopedObjectAccessUnchecked& soa, jthread jtarget) {
art::MutexLock mu(soa.Self(), *art::Locks::thread_list_lock_);
art::Thread* target = nullptr;
jvmtiError err = OK;
if (!ThreadUtil::GetNativeThread(jtarget, soa, &target, &err)) {
return err;
}
// We don't need additional locking here because we hold the Thread_list_lock_.
DCHECK_GT(target->ForceInterpreterCount(), 0u);
target->DecrementForceInterpreterCount();
return OK;
}
void DeoptManager::RemoveDeoptimizationRequester() {
art::Thread* self = art::Thread::Current();
art::ScopedThreadStateChange sts(self, art::ThreadState::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::ThreadState::kSuspended);
deoptimization_status_lock_.ExclusiveLock(self);
deopter_count_++;
if (deopter_count_ == 1) {
ScopedDeoptimizationContext sdc(self, this);
art::instrumentation::Instrumentation* instrumentation =
art::Runtime::Current()->GetInstrumentation();
// Enable deoptimization
instrumentation->EnableDeoptimization();
// Tell instrumentation we will be deopting single threads.
instrumentation->EnableSingleThreadDeopt();
} else {
deoptimization_status_lock_.ExclusiveUnlock(self);
}
}
void DeoptManager::DeoptimizeThread(art::Thread* target) {
// We might or might not be running on the target thread (self) so get Thread::Current
// directly.
art::ScopedThreadSuspension sts(art::Thread::Current(), art::ThreadState::kSuspended);
art::gc::ScopedGCCriticalSection sgccs(art::Thread::Current(),
art::gc::GcCause::kGcCauseDebugger,
art::gc::CollectorType::kCollectorTypeDebugger);
art::ScopedSuspendAll ssa("Instrument thread stack");
// Prepare the stack so methods can be deoptimized as and when required.
// This by itself doesn't cause any methods to deoptimize but enables
// deoptimization on demand.
art::Runtime::Current()->GetInstrumentation()->InstrumentThreadStack(
target,
/* deopt_all_frames= */ false);
}
extern DeoptManager* gDeoptManager;
DeoptManager* DeoptManager::Get() {
return gDeoptManager;
}
} // namespace openjdkjvmti