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/*
* Copyright (C) 2014 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "quick_exception_handler.h"
#include "arch/context.h"
#include "dex_instruction.h"
#include "entrypoints/entrypoint_utils.h"
#include "handle_scope-inl.h"
#include "mirror/art_method-inl.h"
#include "mirror/class-inl.h"
#include "mirror/class_loader.h"
#include "mirror/throwable.h"
#include "verifier/method_verifier.h"
namespace art {
static constexpr bool kDebugExceptionDelivery = false;
static constexpr size_t kInvalidFrameId = 0xffffffff;
QuickExceptionHandler::QuickExceptionHandler(Thread* self, bool is_deoptimization)
: self_(self), context_(self->GetLongJumpContext()), is_deoptimization_(is_deoptimization),
method_tracing_active_(is_deoptimization ||
Runtime::Current()->GetInstrumentation()->AreExitStubsInstalled()),
handler_quick_frame_(nullptr), handler_quick_frame_pc_(0), handler_method_(nullptr),
handler_dex_pc_(0), clear_exception_(false), handler_frame_id_(kInvalidFrameId) {
}
// Finds catch handler or prepares for deoptimization.
class CatchBlockStackVisitor FINAL : public StackVisitor {
public:
CatchBlockStackVisitor(Thread* self, Context* context, Handle<mirror::Throwable>* exception,
QuickExceptionHandler* exception_handler)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_)
: StackVisitor(self, context), self_(self), exception_(exception),
exception_handler_(exception_handler) {
}
bool VisitFrame() OVERRIDE SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
mirror::ArtMethod* method = GetMethod();
exception_handler_->SetHandlerFrameId(GetFrameId());
if (method == nullptr) {
// This is the upcall, we remember the frame and last pc so that we may long jump to them.
exception_handler_->SetHandlerQuickFramePc(GetCurrentQuickFramePc());
exception_handler_->SetHandlerQuickFrame(GetCurrentQuickFrame());
uint32_t next_dex_pc;
mirror::ArtMethod* next_art_method;
bool has_next = GetNextMethodAndDexPc(&next_art_method, &next_dex_pc);
// Report the method that did the down call as the handler.
exception_handler_->SetHandlerDexPc(next_dex_pc);
exception_handler_->SetHandlerMethod(next_art_method);
if (!has_next) {
// No next method? Check exception handler is set up for the unhandled exception handler
// case.
DCHECK_EQ(0U, exception_handler_->GetHandlerDexPc());
DCHECK(nullptr == exception_handler_->GetHandlerMethod());
}
return false; // End stack walk.
}
if (method->IsRuntimeMethod()) {
// Ignore callee save method.
DCHECK(method->IsCalleeSaveMethod());
return true;
}
StackHandleScope<1> hs(self_);
return HandleTryItems(hs.NewHandle(method));
}
private:
bool HandleTryItems(Handle<mirror::ArtMethod> method)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
uint32_t dex_pc = DexFile::kDexNoIndex;
if (!method->IsNative()) {
dex_pc = GetDexPc();
}
if (dex_pc != DexFile::kDexNoIndex) {
bool clear_exception = false;
StackHandleScope<1> hs(Thread::Current());
Handle<mirror::Class> to_find(hs.NewHandle((*exception_)->GetClass()));
uint32_t found_dex_pc = mirror::ArtMethod::FindCatchBlock(method, to_find, dex_pc,
&clear_exception);
exception_handler_->SetClearException(clear_exception);
if (found_dex_pc != DexFile::kDexNoIndex) {
exception_handler_->SetHandlerMethod(method.Get());
exception_handler_->SetHandlerDexPc(found_dex_pc);
exception_handler_->SetHandlerQuickFramePc(method->ToNativePc(found_dex_pc));
exception_handler_->SetHandlerQuickFrame(GetCurrentQuickFrame());
return false; // End stack walk.
}
}
return true; // Continue stack walk.
}
Thread* const self_;
// The exception we're looking for the catch block of.
Handle<mirror::Throwable>* exception_;
// The quick exception handler we're visiting for.
QuickExceptionHandler* const exception_handler_;
DISALLOW_COPY_AND_ASSIGN(CatchBlockStackVisitor);
};
void QuickExceptionHandler::FindCatch(const ThrowLocation& throw_location,
mirror::Throwable* exception,
bool is_exception_reported) {
DCHECK(!is_deoptimization_);
if (kDebugExceptionDelivery) {
mirror::String* msg = exception->GetDetailMessage();
std::string str_msg(msg != nullptr ? msg->ToModifiedUtf8() : "");
self_->DumpStack(LOG(INFO) << "Delivering exception: " << PrettyTypeOf(exception)
<< ": " << str_msg << "\n");
}
StackHandleScope<1> hs(self_);
Handle<mirror::Throwable> exception_ref(hs.NewHandle(exception));
// Walk the stack to find catch handler or prepare for deoptimization.
CatchBlockStackVisitor visitor(self_, context_, &exception_ref, this);
visitor.WalkStack(true);
if (kDebugExceptionDelivery) {
if (handler_quick_frame_->AsMirrorPtr() == nullptr) {
LOG(INFO) << "Handler is upcall";
}
if (handler_method_ != nullptr) {
const DexFile& dex_file = *handler_method_->GetDeclaringClass()->GetDexCache()->GetDexFile();
int line_number = dex_file.GetLineNumFromPC(handler_method_, handler_dex_pc_);
LOG(INFO) << "Handler: " << PrettyMethod(handler_method_) << " (line: " << line_number << ")";
}
}
if (clear_exception_) {
// Exception was cleared as part of delivery.
DCHECK(!self_->IsExceptionPending());
} else {
// Put exception back in root set with clear throw location.
self_->SetException(ThrowLocation(), exception_ref.Get());
self_->SetExceptionReportedToInstrumentation(is_exception_reported);
}
// The debugger may suspend this thread and walk its stack. Let's do this before popping
// instrumentation frames.
if (!is_exception_reported) {
instrumentation::Instrumentation* instrumentation = Runtime::Current()->GetInstrumentation();
instrumentation->ExceptionCaughtEvent(self_, throw_location, handler_method_, handler_dex_pc_,
exception_ref.Get());
// We're not catching this exception but let's remind we already reported the exception above
// to avoid reporting it twice.
self_->SetExceptionReportedToInstrumentation(true);
}
bool caught_exception = (handler_method_ != nullptr && handler_dex_pc_ != DexFile::kDexNoIndex);
if (caught_exception) {
// We're catching this exception so we finish reporting it. We do it here to avoid doing it
// in the compiled code.
self_->SetExceptionReportedToInstrumentation(false);
}
}
// Prepares deoptimization.
class DeoptimizeStackVisitor FINAL : public StackVisitor {
public:
DeoptimizeStackVisitor(Thread* self, Context* context, QuickExceptionHandler* exception_handler)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_)
: StackVisitor(self, context), self_(self), exception_handler_(exception_handler),
prev_shadow_frame_(nullptr) {
CHECK(!self_->HasDeoptimizationShadowFrame());
}
bool VisitFrame() OVERRIDE SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
exception_handler_->SetHandlerFrameId(GetFrameId());
mirror::ArtMethod* method = GetMethod();
if (method == nullptr) {
// This is the upcall, we remember the frame and last pc so that we may long jump to them.
exception_handler_->SetHandlerQuickFramePc(GetCurrentQuickFramePc());
exception_handler_->SetHandlerQuickFrame(GetCurrentQuickFrame());
return false; // End stack walk.
} else if (method->IsRuntimeMethod()) {
// Ignore callee save method.
DCHECK(method->IsCalleeSaveMethod());
return true;
} else {
return HandleDeoptimization(method);
}
}
private:
static VRegKind GetVRegKind(uint16_t reg, const std::vector<int32_t>& kinds) {
return static_cast<VRegKind>(kinds.at(reg * 2));
}
bool HandleDeoptimization(mirror::ArtMethod* m) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
const DexFile::CodeItem* code_item = m->GetCodeItem();
CHECK(code_item != nullptr);
uint16_t num_regs = code_item->registers_size_;
uint32_t dex_pc = GetDexPc();
const Instruction* inst = Instruction::At(code_item->insns_ + dex_pc);
uint32_t new_dex_pc = dex_pc + inst->SizeInCodeUnits();
ShadowFrame* new_frame = ShadowFrame::Create(num_regs, nullptr, m, new_dex_pc);
StackHandleScope<2> hs(self_);
mirror::Class* declaring_class = m->GetDeclaringClass();
Handle<mirror::DexCache> h_dex_cache(hs.NewHandle(declaring_class->GetDexCache()));
Handle<mirror::ClassLoader> h_class_loader(hs.NewHandle(declaring_class->GetClassLoader()));
verifier::MethodVerifier verifier(h_dex_cache->GetDexFile(), &h_dex_cache, &h_class_loader,
&m->GetClassDef(), code_item, m->GetDexMethodIndex(), m,
m->GetAccessFlags(), false, true, true);
verifier.Verify();
const std::vector<int32_t> kinds(verifier.DescribeVRegs(dex_pc));
for (uint16_t reg = 0; reg < num_regs; ++reg) {
VRegKind kind = GetVRegKind(reg, kinds);
switch (kind) {
case kUndefined:
new_frame->SetVReg(reg, 0xEBADDE09);
break;
case kConstant:
new_frame->SetVReg(reg, kinds.at((reg * 2) + 1));
break;
case kReferenceVReg:
new_frame->SetVRegReference(reg,
reinterpret_cast<mirror::Object*>(GetVReg(m, reg, kind)));
break;
case kLongLoVReg:
if (GetVRegKind(reg + 1, kinds), kLongHiVReg) {
// Treat it as a "long" register pair.
new_frame->SetVRegLong(reg, GetVRegPair(m, reg, kLongLoVReg, kLongHiVReg));
} else {
new_frame->SetVReg(reg, GetVReg(m, reg, kind));
}
break;
case kLongHiVReg:
if (GetVRegKind(reg - 1, kinds), kLongLoVReg) {
// Nothing to do: we treated it as a "long" register pair.
} else {
new_frame->SetVReg(reg, GetVReg(m, reg, kind));
}
break;
case kDoubleLoVReg:
if (GetVRegKind(reg + 1, kinds), kDoubleHiVReg) {
// Treat it as a "double" register pair.
new_frame->SetVRegLong(reg, GetVRegPair(m, reg, kDoubleLoVReg, kDoubleHiVReg));
} else {
new_frame->SetVReg(reg, GetVReg(m, reg, kind));
}
break;
case kDoubleHiVReg:
if (GetVRegKind(reg - 1, kinds), kDoubleLoVReg) {
// Nothing to do: we treated it as a "double" register pair.
} else {
new_frame->SetVReg(reg, GetVReg(m, reg, kind));
}
break;
default:
new_frame->SetVReg(reg, GetVReg(m, reg, kind));
break;
}
}
if (prev_shadow_frame_ != nullptr) {
prev_shadow_frame_->SetLink(new_frame);
} else {
self_->SetDeoptimizationShadowFrame(new_frame);
}
prev_shadow_frame_ = new_frame;
return true;
}
Thread* const self_;
QuickExceptionHandler* const exception_handler_;
ShadowFrame* prev_shadow_frame_;
DISALLOW_COPY_AND_ASSIGN(DeoptimizeStackVisitor);
};
void QuickExceptionHandler::DeoptimizeStack() {
DCHECK(is_deoptimization_);
if (kDebugExceptionDelivery) {
self_->DumpStack(LOG(INFO) << "Deoptimizing: ");
}
DeoptimizeStackVisitor visitor(self_, context_, this);
visitor.WalkStack(true);
// Restore deoptimization exception
self_->SetException(ThrowLocation(), Thread::GetDeoptimizationException());
}
// Unwinds all instrumentation stack frame prior to catch handler or upcall.
class InstrumentationStackVisitor : public StackVisitor {
public:
InstrumentationStackVisitor(Thread* self, bool is_deoptimization, size_t frame_id)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_)
: StackVisitor(self, nullptr),
self_(self), frame_id_(frame_id),
instrumentation_frames_to_pop_(0) {
CHECK_NE(frame_id_, kInvalidFrameId);
}
bool VisitFrame() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
size_t current_frame_id = GetFrameId();
if (current_frame_id > frame_id_) {
CHECK(GetMethod() != nullptr);
if (UNLIKELY(GetQuickInstrumentationExitPc() == GetReturnPc())) {
++instrumentation_frames_to_pop_;
}
return true;
} else {
// We reached the frame of the catch handler or the upcall.
return false;
}
}
size_t GetInstrumentationFramesToPop() const {
return instrumentation_frames_to_pop_;
}
private:
Thread* const self_;
const size_t frame_id_;
size_t instrumentation_frames_to_pop_;
DISALLOW_COPY_AND_ASSIGN(InstrumentationStackVisitor);
};
void QuickExceptionHandler::UpdateInstrumentationStack() {
if (method_tracing_active_) {
InstrumentationStackVisitor visitor(self_, is_deoptimization_, handler_frame_id_);
visitor.WalkStack(true);
size_t instrumentation_frames_to_pop = visitor.GetInstrumentationFramesToPop();
instrumentation::Instrumentation* instrumentation = Runtime::Current()->GetInstrumentation();
for (size_t i = 0; i < instrumentation_frames_to_pop; ++i) {
instrumentation->PopMethodForUnwind(self_, is_deoptimization_);
}
}
}
void QuickExceptionHandler::DoLongJump() {
// Place context back on thread so it will be available when we continue.
self_->ReleaseLongJumpContext(context_);
context_->SetSP(reinterpret_cast<uintptr_t>(handler_quick_frame_));
CHECK_NE(handler_quick_frame_pc_, 0u);
context_->SetPC(handler_quick_frame_pc_);
context_->SmashCallerSaves();
context_->DoLongJump();
}
} // namespace art