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/*
* Copyright (C) 2012 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 "art_method-inl.h"
#include "base/callee_save_type.h"
#include "callee_save_frame.h"
#include "class_linker-inl.h"
#include "class_table-inl.h"
#include "dex/dex_file-inl.h"
#include "dex/dex_file_types.h"
#include "entrypoints/entrypoint_utils-inl.h"
#include "gc/heap.h"
#include "mirror/class-inl.h"
#include "mirror/class_loader.h"
#include "mirror/object-inl.h"
#include "mirror/object_array-inl.h"
#include "oat_file.h"
#include "runtime.h"
namespace art {
static void StoreObjectInBss(ArtMethod* outer_method,
const OatFile* oat_file,
size_t bss_offset,
ObjPtr<mirror::Object> object) REQUIRES_SHARED(Locks::mutator_lock_) {
// Used for storing Class or String in .bss GC roots.
static_assert(sizeof(GcRoot<mirror::Class>) == sizeof(GcRoot<mirror::Object>), "Size check.");
static_assert(sizeof(GcRoot<mirror::String>) == sizeof(GcRoot<mirror::Object>), "Size check.");
DCHECK_NE(bss_offset, IndexBssMappingLookup::npos);
DCHECK_ALIGNED(bss_offset, sizeof(GcRoot<mirror::Object>));
if (UNLIKELY(!oat_file->IsExecutable())) {
// There are situations where we execute bytecode tied to an oat file opened
// as non-executable (i.e. the AOT-compiled code cannot be executed) and we
// can JIT that bytecode and get here without the .bss being mmapped.
return;
}
GcRoot<mirror::Object>* slot = reinterpret_cast<GcRoot<mirror::Object>*>(
const_cast<uint8_t*>(oat_file->BssBegin() + bss_offset));
DCHECK_GE(slot, oat_file->GetBssGcRoots().data());
DCHECK_LT(slot, oat_file->GetBssGcRoots().data() + oat_file->GetBssGcRoots().size());
if (slot->IsNull()) {
// This may race with another thread trying to store the very same value but that's OK.
std::atomic<GcRoot<mirror::Object>>* atomic_slot =
reinterpret_cast<std::atomic<GcRoot<mirror::Object>>*>(slot);
static_assert(sizeof(*slot) == sizeof(*atomic_slot), "Size check");
atomic_slot->store(GcRoot<mirror::Object>(object), std::memory_order_release);
// We need a write barrier for the class loader that holds the GC roots in the .bss.
ObjPtr<mirror::ClassLoader> class_loader = outer_method->GetClassLoader();
Runtime* runtime = Runtime::Current();
if (kIsDebugBuild) {
ClassTable* class_table = runtime->GetClassLinker()->ClassTableForClassLoader(class_loader);
CHECK(class_table != nullptr && !class_table->InsertOatFile(oat_file))
<< "Oat file with .bss GC roots was not registered in class table: "
<< oat_file->GetLocation();
}
if (class_loader != nullptr) {
WriteBarrier::ForEveryFieldWrite(class_loader);
} else {
runtime->GetClassLinker()->WriteBarrierForBootOatFileBssRoots(oat_file);
}
} else {
// Each slot serves to store exactly one Class or String.
DCHECK_EQ(object, slot->Read());
}
}
static inline void StoreTypeInBss(ArtMethod* outer_method,
dex::TypeIndex type_idx,
ObjPtr<mirror::Class> resolved_type)
REQUIRES_SHARED(Locks::mutator_lock_) {
const DexFile* dex_file = outer_method->GetDexFile();
DCHECK(dex_file != nullptr);
const OatDexFile* oat_dex_file = dex_file->GetOatDexFile();
if (oat_dex_file != nullptr) {
size_t bss_offset = IndexBssMappingLookup::GetBssOffset(oat_dex_file->GetTypeBssMapping(),
type_idx.index_,
dex_file->NumTypeIds(),
sizeof(GcRoot<mirror::Class>));
if (bss_offset != IndexBssMappingLookup::npos) {
StoreObjectInBss(outer_method, oat_dex_file->GetOatFile(), bss_offset, resolved_type);
}
}
}
static inline void StoreStringInBss(ArtMethod* outer_method,
dex::StringIndex string_idx,
ObjPtr<mirror::String> resolved_string)
REQUIRES_SHARED(Locks::mutator_lock_) {
const DexFile* dex_file = outer_method->GetDexFile();
DCHECK(dex_file != nullptr);
const OatDexFile* oat_dex_file = dex_file->GetOatDexFile();
if (oat_dex_file != nullptr) {
size_t bss_offset = IndexBssMappingLookup::GetBssOffset(oat_dex_file->GetStringBssMapping(),
string_idx.index_,
dex_file->NumStringIds(),
sizeof(GcRoot<mirror::Class>));
if (bss_offset != IndexBssMappingLookup::npos) {
StoreObjectInBss(outer_method, oat_dex_file->GetOatFile(), bss_offset, resolved_string);
}
}
}
static ALWAYS_INLINE bool CanReferenceBss(ArtMethod* outer_method, ArtMethod* caller)
REQUIRES_SHARED(Locks::mutator_lock_) {
// .bss references are used only for AOT-compiled code and only when the instruction
// originates from the outer method's dex file and the type or string index is tied to
// that dex file. As we do not want to check if the call is coming from AOT-compiled
// code (that could be expensive), simply check if the caller has the same dex file.
//
// If we've accepted running AOT-compiled code despite the runtime class loader
// resolving the caller to a different dex file, this check shall prevent us from
// filling the .bss slot and we shall keep going through the slow path. This is slow
// but correct; we do not really care that much about performance in this odd case.
//
// JIT can inline throwing instructions across dex files and this check prevents
// looking up the index in the wrong dex file in that case. If the caller and outer
// method have the same dex file, we may or may not find a .bss slot to update;
// if we do, this can still benefit AOT-compiled code executed later.
return outer_method->GetDexFile() == caller->GetDexFile();
}
extern "C" mirror::Class* artInitializeStaticStorageFromCode(mirror::Class* klass, Thread* self)
REQUIRES_SHARED(Locks::mutator_lock_) {
// Called to ensure static storage base is initialized for direct static field reads and writes.
// A class may be accessing another class' fields when it doesn't have access, as access has been
// given by inheritance.
ScopedQuickEntrypointChecks sqec(self);
DCHECK(klass != nullptr);
ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
StackHandleScope<1> hs(self);
Handle<mirror::Class> h_klass = hs.NewHandle(klass);
bool success = class_linker->EnsureInitialized(
self, h_klass, /* can_init_fields= */ true, /* can_init_parents= */ true);
if (UNLIKELY(!success)) {
return nullptr;
}
return h_klass.Get();
}
extern "C" mirror::Class* artResolveTypeFromCode(uint32_t type_idx, Thread* self)
REQUIRES_SHARED(Locks::mutator_lock_) {
// Called when the .bss slot was empty or for main-path runtime call.
ScopedQuickEntrypointChecks sqec(self);
auto caller_and_outer = GetCalleeSaveMethodCallerAndOuterMethod(
self, CalleeSaveType::kSaveEverythingForClinit);
ArtMethod* caller = caller_and_outer.caller;
ObjPtr<mirror::Class> result = ResolveVerifyAndClinit(dex::TypeIndex(type_idx),
caller,
self,
/* can_run_clinit= */ false,
/* verify_access= */ false);
if (LIKELY(result != nullptr) && CanReferenceBss(caller_and_outer.outer_method, caller)) {
StoreTypeInBss(caller_and_outer.outer_method, dex::TypeIndex(type_idx), result);
}
return result.Ptr();
}
extern "C" mirror::Class* artResolveTypeAndVerifyAccessFromCode(uint32_t type_idx, Thread* self)
REQUIRES_SHARED(Locks::mutator_lock_) {
// Called when caller isn't guaranteed to have access to a type.
ScopedQuickEntrypointChecks sqec(self);
auto caller_and_outer = GetCalleeSaveMethodCallerAndOuterMethod(self,
CalleeSaveType::kSaveEverything);
ArtMethod* caller = caller_and_outer.caller;
ObjPtr<mirror::Class> result = ResolveVerifyAndClinit(dex::TypeIndex(type_idx),
caller,
self,
/* can_run_clinit= */ false,
/* verify_access= */ true);
// Do not StoreTypeInBss(); access check entrypoint is never used together with .bss.
return result.Ptr();
}
extern "C" mirror::MethodHandle* artResolveMethodHandleFromCode(uint32_t method_handle_idx,
Thread* self)
REQUIRES_SHARED(Locks::mutator_lock_) {
ScopedQuickEntrypointChecks sqec(self);
auto caller_and_outer =
GetCalleeSaveMethodCallerAndOuterMethod(self, CalleeSaveType::kSaveEverything);
ArtMethod* caller = caller_and_outer.caller;
ObjPtr<mirror::MethodHandle> result = ResolveMethodHandleFromCode(caller, method_handle_idx);
return result.Ptr();
}
extern "C" mirror::MethodType* artResolveMethodTypeFromCode(uint32_t proto_idx, Thread* self)
REQUIRES_SHARED(Locks::mutator_lock_) {
ScopedQuickEntrypointChecks sqec(self);
auto caller_and_outer = GetCalleeSaveMethodCallerAndOuterMethod(self,
CalleeSaveType::kSaveEverything);
ArtMethod* caller = caller_and_outer.caller;
ObjPtr<mirror::MethodType> result = ResolveMethodTypeFromCode(caller, dex::ProtoIndex(proto_idx));
return result.Ptr();
}
extern "C" mirror::String* artResolveStringFromCode(int32_t string_idx, Thread* self)
REQUIRES_SHARED(Locks::mutator_lock_) {
ScopedQuickEntrypointChecks sqec(self);
auto caller_and_outer = GetCalleeSaveMethodCallerAndOuterMethod(self,
CalleeSaveType::kSaveEverything);
ArtMethod* caller = caller_and_outer.caller;
ObjPtr<mirror::String> result =
Runtime::Current()->GetClassLinker()->ResolveString(dex::StringIndex(string_idx), caller);
if (LIKELY(result != nullptr) && CanReferenceBss(caller_and_outer.outer_method, caller)) {
StoreStringInBss(caller_and_outer.outer_method, dex::StringIndex(string_idx), result);
}
return result.Ptr();
}
} // namespace art
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