chromium/v8/src/wasm/wasm-code-pointer-table.h

// Copyright 2024 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_WASM_WASM_CODE_POINTER_TABLE_H_
#define V8_WASM_WASM_CODE_POINTER_TABLE_H_

#include "include/v8-internal.h"
#include "src/common/segmented-table.h"

#if !V8_ENABLE_WEBASSEMBLY
#error This header should only be included if WebAssembly is enabled.
#endif  // !V8_ENABLE_WEBASSEMBLY

namespace v8::internal::wasm {

// Defines the entries in the WasmCodePointerTable and specifies the encoding.
// When entries are in use, they contain the address of a valid Wasm code entry,
// while free entries contain an index to the next element in the freelist.
//
// All reads and writes use relaxed memory ordering and need to be synchronized
// by the caller.
struct WasmCodePointerTableEntry { … };

// A table for storing valid Wasm code entrypoints. This table allows enforcing
// forward-edge CFI for Wasm calls:
// * The table gets write-protected (e.g. with pkeys) to prevent corruption of
//   entries.
// * At write time, we will check that the value is a valid entrypoint as
//   tracked in our CFI metadata.
// * Wasm calls can then be replaced with a bounds-checked table lookup + call
//   to enforce that only valid entrypoints can be called.
//
// All methods are thread-safe if not specified otherwise.
class V8_EXPORT_PRIVATE WasmCodePointerTable
    : public SegmentedTable<WasmCodePointerTableEntry,
                            kCodePointerTableReservationSize> { … };

V8_EXPORT_PRIVATE WasmCodePointerTable* GetProcessWideWasmCodePointerTable();

}  // namespace v8::internal::wasm

#endif  // V8_WASM_WASM_CODE_POINTER_TABLE_H_