/*
* 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 "art_method-inl.h"
#include "dex_instruction.h"
#include "entrypoints/entrypoint_utils.h"
#include "entrypoints/runtime_asm_entrypoints.h"
#include "handle_scope-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 kInvalidFrameDepth = 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_depth_(kInvalidFrameDepth) {
}
// 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, StackVisitor::StackWalkKind::kIncludeInlinedFrames),
self_(self),
exception_(exception),
exception_handler_(exception_handler) {
}
bool VisitFrame() OVERRIDE SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
ArtMethod* method = GetMethod();
exception_handler_->SetHandlerFrameDepth(GetFrameDepth());
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;
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;
}
return HandleTryItems(method);
}
private:
bool HandleTryItems(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(self_);
Handle<mirror::Class> to_find(hs.NewHandle((*exception_)->GetClass()));
uint32_t found_dex_pc = method->FindCatchBlock(to_find, dex_pc, &clear_exception);
exception_handler_->SetClearException(clear_exception);
if (found_dex_pc != DexFile::kDexNoIndex) {
exception_handler_->SetHandlerMethod(method);
exception_handler_->SetHandlerDexPc(found_dex_pc);
exception_handler_->SetHandlerQuickFramePc(method->ToNativeQuickPc(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(mirror::Throwable* exception) {
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_ == 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(exception_ref.Get());
}
// The debugger may suspend this thread and walk its stack. Let's do this before popping
// instrumentation frames.
instrumentation::Instrumentation* instrumentation = Runtime::Current()->GetInstrumentation();
if (instrumentation->HasExceptionCaughtListeners()
&& self_->IsExceptionThrownByCurrentMethod(exception)) {
instrumentation->ExceptionCaughtEvent(self_, exception_ref.Get());
}
}
// 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, StackVisitor::StackWalkKind::kIncludeInlinedFrames),
self_(self),
exception_handler_(exception_handler),
prev_shadow_frame_(nullptr),
stacked_shadow_frame_pushed_(false) {
}
bool VisitFrame() OVERRIDE SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
exception_handler_->SetHandlerFrameDepth(GetFrameDepth());
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());
if (!stacked_shadow_frame_pushed_) {
// In case there is no deoptimized shadow frame for this upcall, we still
// need to push a nullptr to the stack since there is always a matching pop after
// the long jump.
self_->PushStackedShadowFrame(nullptr, StackedShadowFrameType::kDeoptimizationShadowFrame);
stacked_shadow_frame_pushed_ = true;
}
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(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();
StackHandleScope<2> hs(self_); // Dex cache, class loader and method.
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(self_, h_dex_cache->GetDexFile(), h_dex_cache, h_class_loader,
&m->GetClassDef(), code_item, m->GetDexMethodIndex(),
m, m->GetAccessFlags(), true, true, true, true);
bool verifier_success = verifier.Verify();
CHECK(verifier_success) << PrettyMethod(m);
ShadowFrame* new_frame = ShadowFrame::CreateDeoptimizedFrame(num_regs, nullptr, m, dex_pc);
{
ScopedStackedShadowFramePusher pusher(self_, new_frame,
StackedShadowFrameType::kShadowFrameUnderConstruction);
const std::vector<int32_t> kinds(verifier.DescribeVRegs(dex_pc));
// Markers for dead values, used when the verifier knows a Dex register is undefined,
// or when the compiler knows the register has not been initialized, or is not used
// anymore in the method.
static constexpr uint32_t kDeadValue = 0xEBADDE09;
static constexpr uint64_t kLongDeadValue = 0xEBADDE09EBADDE09;
for (uint16_t reg = 0; reg < num_regs; ++reg) {
VRegKind kind = GetVRegKind(reg, kinds);
switch (kind) {
case kUndefined:
new_frame->SetVReg(reg, kDeadValue);
break;
case kConstant:
new_frame->SetVReg(reg, kinds.at((reg * 2) + 1));
break;
case kReferenceVReg: {
uint32_t value = 0;
// Check IsReferenceVReg in case the compiled GC map doesn't agree with the verifier.
// We don't want to copy a stale reference into the shadow frame as a reference.
// b/20736048
if (GetVReg(m, reg, kind, &value) && IsReferenceVReg(m, reg)) {
new_frame->SetVRegReference(reg, reinterpret_cast<mirror::Object*>(value));
} else {
new_frame->SetVReg(reg, kDeadValue);
}
break;
}
case kLongLoVReg:
if (GetVRegKind(reg + 1, kinds) == kLongHiVReg) {
// Treat it as a "long" register pair.
uint64_t value = 0;
if (GetVRegPair(m, reg, kLongLoVReg, kLongHiVReg, &value)) {
new_frame->SetVRegLong(reg, value);
} else {
new_frame->SetVRegLong(reg, kLongDeadValue);
}
} else {
uint32_t value = 0;
if (GetVReg(m, reg, kind, &value)) {
new_frame->SetVReg(reg, value);
} else {
new_frame->SetVReg(reg, kDeadValue);
}
}
break;
case kLongHiVReg:
if (GetVRegKind(reg - 1, kinds) == kLongLoVReg) {
// Nothing to do: we treated it as a "long" register pair.
} else {
uint32_t value = 0;
if (GetVReg(m, reg, kind, &value)) {
new_frame->SetVReg(reg, value);
} else {
new_frame->SetVReg(reg, kDeadValue);
}
}
break;
case kDoubleLoVReg:
if (GetVRegKind(reg + 1, kinds) == kDoubleHiVReg) {
uint64_t value = 0;
if (GetVRegPair(m, reg, kDoubleLoVReg, kDoubleHiVReg, &value)) {
// Treat it as a "double" register pair.
new_frame->SetVRegLong(reg, value);
} else {
new_frame->SetVRegLong(reg, kLongDeadValue);
}
} else {
uint32_t value = 0;
if (GetVReg(m, reg, kind, &value)) {
new_frame->SetVReg(reg, value);
} else {
new_frame->SetVReg(reg, kDeadValue);
}
}
break;
case kDoubleHiVReg:
if (GetVRegKind(reg - 1, kinds) == kDoubleLoVReg) {
// Nothing to do: we treated it as a "double" register pair.
} else {
uint32_t value = 0;
if (GetVReg(m, reg, kind, &value)) {
new_frame->SetVReg(reg, value);
} else {
new_frame->SetVReg(reg, kDeadValue);
}
}
break;
default:
uint32_t value = 0;
if (GetVReg(m, reg, kind, &value)) {
new_frame->SetVReg(reg, value);
} else {
new_frame->SetVReg(reg, kDeadValue);
}
break;
}
}
}
if (prev_shadow_frame_ != nullptr) {
prev_shadow_frame_->SetLink(new_frame);
} else {
// Will be popped after the long jump after DeoptimizeStack(),
// right before interpreter::EnterInterpreterFromDeoptimize().
stacked_shadow_frame_pushed_ = true;
self_->PushStackedShadowFrame(new_frame, StackedShadowFrameType::kDeoptimizationShadowFrame);
}
prev_shadow_frame_ = new_frame;
return true;
}
Thread* const self_;
QuickExceptionHandler* const exception_handler_;
ShadowFrame* prev_shadow_frame_;
bool stacked_shadow_frame_pushed_;
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(Thread::GetDeoptimizationException());
}
// Unwinds all instrumentation stack frame prior to catch handler or upcall.
class InstrumentationStackVisitor : public StackVisitor {
public:
InstrumentationStackVisitor(Thread* self, size_t frame_depth)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_)
: StackVisitor(self, nullptr, StackVisitor::StackWalkKind::kIncludeInlinedFrames),
frame_depth_(frame_depth),
instrumentation_frames_to_pop_(0) {
CHECK_NE(frame_depth_, kInvalidFrameDepth);
}
bool VisitFrame() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
size_t current_frame_depth = GetFrameDepth();
if (current_frame_depth < frame_depth_) {
CHECK(GetMethod() != nullptr);
if (UNLIKELY(reinterpret_cast<uintptr_t>(GetQuickInstrumentationExitPc()) == GetReturnPc())) {
if (!IsInInlinedFrame()) {
// We do not count inlined frames, because we do not instrument them. The reason we
// include them in the stack walking is the check against `frame_depth_`, which is
// given to us by a visitor that visits inlined frames.
++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:
const size_t frame_depth_;
size_t instrumentation_frames_to_pop_;
DISALLOW_COPY_AND_ASSIGN(InstrumentationStackVisitor);
};
void QuickExceptionHandler::UpdateInstrumentationStack() {
if (method_tracing_active_) {
InstrumentationStackVisitor visitor(self_, handler_frame_depth_);
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();
UNREACHABLE();
}
} // namespace art