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// 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_SANDBOX_CODE_POINTER_INL_H_
#define V8_SANDBOX_CODE_POINTER_INL_H_
#include "include/v8-internal.h"
#include "src/base/atomic-utils.h"
#include "src/execution/isolate.h"
#include "src/sandbox/code-pointer-table-inl.h"
#include "src/sandbox/code-pointer.h"
namespace v8 {
namespace internal {
V8_INLINE void InitCodePointerTableEntryField(Address field_address,
Isolate* isolate,
Tagged<HeapObject> owning_code,
Address entrypoint) {
#ifdef V8_ENABLE_SANDBOX
CodePointerTable::Space* space =
ReadOnlyHeap::Contains(field_address)
? isolate->read_only_heap()->code_pointer_space()
: isolate->heap()->code_pointer_space();
CodePointerHandle handle =
GetProcessWideCodePointerTable()->AllocateAndInitializeEntry(
space, owning_code.ptr(), entrypoint);
// Use a Release_Store to ensure that the store of the pointer into the
// table is not reordered after the store of the handle. Otherwise, other
// threads may access an uninitialized table entry and crash.
auto location = reinterpret_cast<CodePointerHandle*>(field_address);
base::AsAtomic32::Release_Store(location, handle);
#else
UNREACHABLE();
#endif // V8_ENABLE_SANDBOX
}
V8_INLINE Address
ReadCodeEntrypointViaIndirectPointerField(Address field_address) {
#ifdef V8_ENABLE_SANDBOX
// Handles may be written to objects from other threads so the handle needs
// to be loaded atomically. We assume that the load from the table cannot
// be reordered before the load of the handle due to the data dependency
// between the two loads and therefore use relaxed memory ordering, but
// technically we should use memory_order_consume here.
auto location = reinterpret_cast<CodePointerHandle*>(field_address);
CodePointerHandle handle = base::AsAtomic32::Relaxed_Load(location);
return GetProcessWideCodePointerTable()->GetEntrypoint(handle);
#else
UNREACHABLE();
#endif // V8_ENABLE_SANDBOX
}
V8_INLINE void WriteCodeEntrypointViaIndirectPointerField(Address field_address,
Address value) {
#ifdef V8_ENABLE_SANDBOX
// See comment above for why this is a Relaxed_Load.
auto location = reinterpret_cast<CodePointerHandle*>(field_address);
CodePointerHandle handle = base::AsAtomic32::Relaxed_Load(location);
GetProcessWideCodePointerTable()->SetEntrypoint(handle, value);
#else
UNREACHABLE();
#endif // V8_ENABLE_SANDBOX
}
} // namespace internal
} // namespace v8
#endif // V8_SANDBOX_CODE_POINTER_INL_H_
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