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// Copyright 2018 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_SNAPSHOT_EMBEDDED_EMBEDDED_DATA_H_
#define V8_SNAPSHOT_EMBEDDED_EMBEDDED_DATA_H_
#include "src/base/macros.h"
#include "src/builtins/builtins.h"
#include "src/common/globals.h"
#include "src/execution/isolate.h"
#include "src/heap/code-range.h"
namespace v8 {
namespace internal {
class Code;
class Isolate;
// Wraps an off-heap instruction stream.
// TODO(jgruber,v8:6666): Remove this class.
class InstructionStream final : public AllStatic {
public:
// Returns true, iff the given pc points into an off-heap instruction stream.
static bool PcIsOffHeap(Isolate* isolate, Address pc);
// If the address belongs to the embedded code blob, predictably converts it
// to uint32 by calculating offset from the embedded code blob start and
// returns true, and false otherwise.
static bool TryGetAddressForHashing(Isolate* isolate, Address address,
uint32_t* hashable_address);
// Returns the corresponding builtin ID if lookup succeeds, and kNoBuiltinId
// otherwise.
static Builtin TryLookupCode(Isolate* isolate, Address address);
// During snapshot creation, we first create an executable off-heap area
// containing all off-heap code. The area is guaranteed to be contiguous.
// Note that this only applies when building the snapshot, e.g. for
// mksnapshot. Otherwise, off-heap code is embedded directly into the binary.
static void CreateOffHeapInstructionStream(Isolate* isolate, uint8_t** code,
uint32_t* code_size,
uint8_t** data,
uint32_t* data_size);
static void FreeOffHeapInstructionStream(uint8_t* code, uint32_t code_size,
uint8_t* data, uint32_t data_size);
};
class EmbeddedData final {
public:
static EmbeddedData FromIsolate(Isolate* isolate);
static EmbeddedData FromBlob() {
return EmbeddedData(Isolate::CurrentEmbeddedBlobCode(),
Isolate::CurrentEmbeddedBlobCodeSize(),
Isolate::CurrentEmbeddedBlobData(),
Isolate::CurrentEmbeddedBlobDataSize());
}
static EmbeddedData FromBlob(Isolate* isolate) {
return EmbeddedData(
isolate->embedded_blob_code(), isolate->embedded_blob_code_size(),
isolate->embedded_blob_data(), isolate->embedded_blob_data_size());
}
static EmbeddedData FromBlob(CodeRange* code_range) {
return EmbeddedData(code_range->embedded_blob_code_copy(),
Isolate::CurrentEmbeddedBlobCodeSize(),
Isolate::CurrentEmbeddedBlobData(),
Isolate::CurrentEmbeddedBlobDataSize());
}
const uint8_t* code() const { return code_; }
uint32_t code_size() const { return code_size_; }
const uint8_t* data() const { return data_; }
uint32_t data_size() const { return data_size_; }
bool IsInCodeRange(Address pc) const {
Address start = reinterpret_cast<Address>(code_);
return (start <= pc) && (pc < start + code_size_);
}
// When short builtin calls optimization is enabled for the Isolate, there
// will be two builtins instruction streams executed: the embedded one and
// the one un-embedded into the per-Isolate code range. In most of the cases,
// the per-Isolate instructions will be used but in some cases (like builtin
// calls from Wasm) the embedded instruction stream could be used.
// If the requested PC belongs to the embedded code blob - it'll be returned,
// and the per-Isolate blob otherwise.
// See http://crbug.com/v8/11527 for details.
inline static EmbeddedData GetEmbeddedDataForPC(Isolate* isolate,
Address maybe_builtin_pc) {
EmbeddedData d = EmbeddedData::FromBlob(isolate);
if (isolate->is_short_builtin_calls_enabled() &&
!d.IsInCodeRange(maybe_builtin_pc)) {
EmbeddedData global_d = EmbeddedData::FromBlob();
// If the pc does not belong to the embedded code blob we should be using
// the un-embedded one.
if (global_d.IsInCodeRange(maybe_builtin_pc)) return global_d;
}
return d;
}
void Dispose() {
delete[] code_;
code_ = nullptr;
delete[] data_;
data_ = nullptr;
}
Address InstructionStartOfBuiltin(Builtin builtin) const;
uint32_t InstructionSizeOfBuiltin(Builtin builtin) const;
Address InstructionStartOfBytecodeHandlers() const;
Address InstructionEndOfBytecodeHandlers() const;
Address MetadataStartOfBuiltin(Builtin builtin) const;
uint32_t MetadataSizeOfBuiltin(Builtin builtin) const;
uint32_t AddressForHashing(Address addr) {
DCHECK(IsInCodeRange(addr));
Address start = reinterpret_cast<Address>(code_);
return static_cast<uint32_t>(addr - start);
}
// Padded with kCodeAlignment.
// TODO(v8:11045): Consider removing code alignment.
uint32_t PaddedInstructionSizeOfBuiltin(Builtin builtin) const {
uint32_t size = InstructionSizeOfBuiltin(builtin);
CHECK_NE(size, 0);
return PadAndAlignCode(size);
}
size_t CreateEmbeddedBlobDataHash() const;
size_t CreateEmbeddedBlobCodeHash() const;
size_t EmbeddedBlobDataHash() const {
return *reinterpret_cast<const size_t*>(data_ +
EmbeddedBlobDataHashOffset());
}
size_t EmbeddedBlobCodeHash() const {
return *reinterpret_cast<const size_t*>(data_ +
EmbeddedBlobCodeHashOffset());
}
size_t IsolateHash() const {
return *reinterpret_cast<const size_t*>(data_ + IsolateHashOffset());
}
// Blob layout information for a single instruction stream. Corresponds
// roughly to Code object layout (see the instruction and metadata area).
struct LayoutDescription {
// The offset and (unpadded) length of this builtin's instruction area
// from the start of the embedded code section.
uint32_t instruction_offset;
uint32_t instruction_length;
// The offset and (unpadded) length of this builtin's metadata area
// from the start of the embedded code section.
uint32_t metadata_offset;
uint32_t metadata_length;
};
STATIC_ASSERT(offsetof(LayoutDescription, instruction_offset) ==
0 * kUInt32Size);
STATIC_ASSERT(offsetof(LayoutDescription, instruction_length) ==
1 * kUInt32Size);
STATIC_ASSERT(offsetof(LayoutDescription, metadata_offset) ==
2 * kUInt32Size);
STATIC_ASSERT(offsetof(LayoutDescription, metadata_length) ==
3 * kUInt32Size);
STATIC_ASSERT(sizeof(LayoutDescription) == 4 * kUInt32Size);
// The layout of the blob is as follows:
//
// data:
// [0] hash of the data section
// [1] hash of the code section
// [2] hash of embedded-blob-relevant heap objects
// [3] layout description of instruction stream 0
// ... layout descriptions
// [x] metadata section of builtin 0
// ... metadata sections
//
// code:
// [0] instruction section of builtin 0
// ... instruction sections
static constexpr uint32_t kTableSize = Builtins::kBuiltinCount;
static constexpr uint32_t EmbeddedBlobDataHashOffset() { return 0; }
static constexpr uint32_t EmbeddedBlobDataHashSize() { return kSizetSize; }
static constexpr uint32_t EmbeddedBlobCodeHashOffset() {
return EmbeddedBlobDataHashOffset() + EmbeddedBlobDataHashSize();
}
static constexpr uint32_t EmbeddedBlobCodeHashSize() { return kSizetSize; }
static constexpr uint32_t IsolateHashOffset() {
return EmbeddedBlobCodeHashOffset() + EmbeddedBlobCodeHashSize();
}
static constexpr uint32_t IsolateHashSize() { return kSizetSize; }
static constexpr uint32_t LayoutDescriptionTableOffset() {
return IsolateHashOffset() + IsolateHashSize();
}
static constexpr uint32_t LayoutDescriptionTableSize() {
return sizeof(struct LayoutDescription) * kTableSize;
}
static constexpr uint32_t FixedDataSize() {
return LayoutDescriptionTableOffset() + LayoutDescriptionTableSize();
}
// The variable-size data section starts here.
static constexpr uint32_t RawMetadataOffset() { return FixedDataSize(); }
// Code is in its own dedicated section.
static constexpr uint32_t RawCodeOffset() { return 0; }
private:
EmbeddedData(const uint8_t* code, uint32_t code_size, const uint8_t* data,
uint32_t data_size)
: code_(code), code_size_(code_size), data_(data), data_size_(data_size) {
DCHECK_NOT_NULL(code);
DCHECK_LT(0, code_size);
DCHECK_NOT_NULL(data);
DCHECK_LT(0, data_size);
}
const uint8_t* RawCode() const { return code_ + RawCodeOffset(); }
const LayoutDescription* LayoutDescription() const {
return reinterpret_cast<const struct LayoutDescription*>(
data_ + LayoutDescriptionTableOffset());
}
const uint8_t* RawMetadata() const { return data_ + RawMetadataOffset(); }
static constexpr int PadAndAlignCode(int size) {
// Ensure we have at least one byte trailing the actual builtin
// instructions which we can later fill with int3.
return RoundUp<kCodeAlignment>(size + 1);
}
static constexpr int PadAndAlignData(int size) {
// Ensure we have at least one byte trailing the actual builtin
// instructions which we can later fill with int3.
return RoundUp<Code::kMetadataAlignment>(size);
}
void PrintStatistics() const;
// The code section contains instruction streams. It is guaranteed to have
// execute permissions, and may have read permissions.
const uint8_t* code_;
uint32_t code_size_;
// The data section contains both descriptions of the code section (hashes,
// offsets, sizes) and metadata describing Code objects (see
// Code::MetadataStart()). It is guaranteed to have read permissions.
const uint8_t* data_;
uint32_t data_size_;
};
} // namespace internal
} // namespace v8
#endif // V8_SNAPSHOT_EMBEDDED_EMBEDDED_DATA_H_
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