| // Copyright 2023 the V8 project authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef V8_OBJECTS_INSTRUCTION_STREAM_H_ |
| #define V8_OBJECTS_INSTRUCTION_STREAM_H_ |
| |
| #ifdef DEBUG |
| #include <set> |
| #endif |
| |
| #include "src/codegen/code-desc.h" |
| #include "src/objects/trusted-object.h" |
| |
| // Has to be the last include (doesn't have include guards): |
| #include "src/objects/object-macros.h" |
| |
| namespace v8 { |
| namespace internal { |
| |
| class Code; |
| class WritableJitAllocation; |
| |
| // InstructionStream contains the instruction stream for V8-generated code |
| // objects. |
| // |
| // When V8_EXTERNAL_CODE_SPACE is enabled, InstructionStream objects are |
| // allocated in a separate pointer compression cage instead of the cage where |
| // all the other objects are allocated. |
| // |
| // An InstructionStream is a trusted object as it lives outside of the sandbox |
| // and contains trusted content (machine code). However, it is special in that |
| // it doesn't live in the trusted space but instead in the code space. |
| class InstructionStream : public TrustedObject { |
| public: |
| NEVER_READ_ONLY_SPACE |
| |
| // All InstructionStream objects have the following layout: |
| // |
| // +--------------------------+ |
| // | header | |
| // +--------------------------+ <-- body_start() |
| // | instructions | == instruction_start() |
| // | ... | |
| // | padded to meta alignment | see kMetadataAlignment |
| // +--------------------------+ <-- instruction_end() |
| // | metadata | == metadata_start() (MS) |
| // | ... | |
| // | | <-- MS + handler_table_offset() |
| // | | <-- MS + constant_pool_offset() |
| // | | <-- MS + code_comments_offset() |
| // | | <-- MS + unwinding_info_offset() |
| // | padded to obj alignment | |
| // +--------------------------+ <-- metadata_end() == body_end() |
| // | padded to kCodeAlignmentMinusCodeHeader |
| // +--------------------------+ |
| // |
| // In other words, the variable-size 'body' consists of 'instructions' and |
| // 'metadata'. |
| |
| // Constants for use in static asserts, stating whether the body is adjacent, |
| // i.e. instructions and metadata areas are adjacent. |
| static constexpr bool kOnHeapBodyIsContiguous = true; |
| static constexpr bool kOffHeapBodyIsContiguous = false; |
| static constexpr bool kBodyIsContiguous = |
| kOnHeapBodyIsContiguous && kOffHeapBodyIsContiguous; |
| |
| inline Address instruction_start() const; |
| |
| // The metadata section is aligned to this value. |
| static constexpr int kMetadataAlignment = kIntSize; |
| |
| // [code]: The associated Code object. |
| // |
| // Set to Smi::zero() during initialization. Heap iterators may see |
| // InstructionStream objects in this state. |
| inline Tagged<Code> code(AcquireLoadTag tag) const; |
| inline void set_code(Tagged<Code> value, ReleaseStoreTag tag); |
| inline Tagged<Object> raw_code(AcquireLoadTag tag) const; |
| // Use when the InstructionStream may be uninitialized: |
| inline bool TryGetCode(Tagged<Code>* code_out, AcquireLoadTag tag) const; |
| inline bool TryGetCodeUnchecked(Tagged<Code>* code_out, |
| AcquireLoadTag tag) const; |
| |
| inline Address constant_pool() const; |
| |
| // [relocation_info]: InstructionStream relocation information. |
| inline Tagged<ByteArray> relocation_info() const; |
| // Unchecked accessor to be used during GC. |
| inline Tagged<ByteArray> unchecked_relocation_info() const; |
| |
| inline uint8_t* relocation_start() const; |
| inline uint8_t* relocation_end() const; |
| inline int relocation_size() const; |
| |
| // The size of the entire body section, containing instructions and inlined |
| // metadata. |
| DECL_PRIMITIVE_GETTER(body_size, uint32_t) |
| inline Address body_end() const; |
| |
| static constexpr int TrailingPaddingSizeFor(uint32_t body_size) { |
| return RoundUp<kCodeAlignment>(kHeaderSize + body_size) - kHeaderSize - |
| body_size; |
| } |
| static constexpr int SizeFor(int body_size) { |
| return kHeaderSize + body_size + TrailingPaddingSizeFor(body_size); |
| } |
| inline int Size() const; |
| |
| static inline Tagged<InstructionStream> FromTargetAddress(Address address); |
| static inline Tagged<InstructionStream> FromEntryAddress( |
| Address location_of_address); |
| |
| // Relocate the code by delta bytes. |
| void Relocate(WritableJitAllocation& jit_allocation, intptr_t delta); |
| |
| static V8_INLINE Tagged<InstructionStream> Initialize( |
| Tagged<HeapObject> self, Tagged<Map> map, uint32_t body_size, |
| int constant_pool_offset, Tagged<ByteArray> reloc_info); |
| V8_INLINE void Finalize(Tagged<Code> code, Tagged<ByteArray> reloc_info, |
| CodeDesc desc, Heap* heap); |
| V8_INLINE bool IsFullyInitialized(); |
| |
| DECL_CAST(InstructionStream) |
| DECL_PRINTER(InstructionStream) |
| DECL_VERIFIER(InstructionStream) |
| |
| // Layout description. |
| #define ISTREAM_FIELDS(V) \ |
| V(kCodeOffset, kProtectedPointerSize) \ |
| V(kStartOfStrongFieldsOffset, 0) \ |
| V(kRelocationInfoOffset, kTaggedSize) \ |
| V(kEndOfStrongFieldsOffset, 0) \ |
| /* Data or code not directly visited by GC directly starts here. */ \ |
| V(kDataStart, 0) \ |
| V(kBodySizeOffset, kUInt32Size) \ |
| V(kConstantPoolOffsetOffset, V8_EMBEDDED_CONSTANT_POOL_BOOL ? kIntSize : 0) \ |
| V(kUnalignedSize, OBJECT_POINTER_PADDING(kUnalignedSize)) \ |
| V(kHeaderSize, 0) |
| DEFINE_FIELD_OFFSET_CONSTANTS(TrustedObject::kHeaderSize, ISTREAM_FIELDS) |
| #undef ISTREAM_FIELDS |
| |
| static_assert(kCodeAlignment >= kHeaderSize); |
| // We do two things to ensure kCodeAlignment of the entry address: |
| // 1) Add kCodeAlignmentMinusCodeHeader padding once in the beginning of every |
| // MemoryChunk. |
| // 2) Round up all IStream allocations to a multiple of kCodeAlignment, see |
| // TrailingPaddingSizeFor. |
| // Together, the IStream object itself will always start at offset |
| // kCodeAlignmentMinusCodeHeader, which aligns the entry to kCodeAlignment. |
| static constexpr int kCodeAlignmentMinusCodeHeader = |
| kCodeAlignment - kHeaderSize; |
| |
| class BodyDescriptor; |
| |
| private: |
| friend class Factory; |
| |
| class V8_NODISCARD WriteBarrierPromise { |
| public: |
| WriteBarrierPromise() = default; |
| WriteBarrierPromise(WriteBarrierPromise&&) V8_NOEXCEPT = default; |
| WriteBarrierPromise(const WriteBarrierPromise&) = delete; |
| WriteBarrierPromise& operator=(const WriteBarrierPromise&) = delete; |
| |
| #ifdef DEBUG |
| void RegisterAddress(Address address); |
| void ResolveAddress(Address address); |
| ~WriteBarrierPromise(); |
| |
| private: |
| std::set<Address> delayed_write_barriers_; |
| #else |
| void RegisterAddress(Address address) {} |
| void ResolveAddress(Address address) {} |
| #endif |
| }; |
| |
| // Migrate code from desc without flushing the instruction cache. This |
| // function will not trigger any write barriers and the caller needs to call |
| // RelocateFromDescWriteBarriers afterwards. This is split into two functions, |
| // since the former needs write access to executable memory and we need to |
| // keep this critical section minimal since any memory write poses attack |
| // surface for CFI and will require special validation. |
| WriteBarrierPromise RelocateFromDesc(WritableJitAllocation& jit_allocation, |
| Heap* heap, const CodeDesc& desc, |
| Address constant_pool, |
| const DisallowGarbageCollection& no_gc); |
| void RelocateFromDescWriteBarriers(Heap* heap, const CodeDesc& desc, |
| Address constant_pool, |
| WriteBarrierPromise& promise, |
| const DisallowGarbageCollection& no_gc); |
| |
| // Must be used when loading any of InstructionStream's tagged fields. |
| static inline PtrComprCageBase main_cage_base(); |
| |
| OBJECT_CONSTRUCTORS(InstructionStream, TrustedObject); |
| }; |
| |
| } // namespace internal |
| } // namespace v8 |
| |
| #include "src/objects/object-macros-undef.h" |
| |
| #endif // V8_OBJECTS_INSTRUCTION_STREAM_H_ |
