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// Copyright 2021 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_HEAP_CPPGC_MEMORY_H_
#define V8_HEAP_CPPGC_MEMORY_H_
#include <cstddef>
#include <cstdint>
#include <cstring>
#include "src/base/macros.h"
#include "src/base/sanitizer/asan.h"
#include "src/base/sanitizer/msan.h"
#include "src/heap/cppgc/globals.h"
namespace cppgc {
namespace internal {
V8_NOINLINE DISABLE_ASAN void NoSanitizeMemset(void* address, char c,
size_t bytes);
static constexpr uint8_t kZappedValue = 0xdc;
V8_INLINE void ZapMemory(void* address, size_t size) {
// The lowest bit of the zapped value should be 0 so that zapped object are
// never viewed as fully constructed objects.
memset(address, kZappedValue, size);
}
V8_INLINE void CheckMemoryIsZapped(const void* address, size_t size) {
for (size_t i = 0; i < size; i++) {
CHECK_EQ(kZappedValue, reinterpret_cast<ConstAddress>(address)[i]);
}
}
V8_INLINE void CheckMemoryIsZero(const void* address, size_t size) {
for (size_t i = 0; i < size; i++) {
CHECK_EQ(0, reinterpret_cast<ConstAddress>(address)[i]);
}
}
// Together `SetMemoryAccessible()` and `SetMemoryInaccessible()` form the
// memory access model for allocation and free.
V8_INLINE void SetMemoryAccessible(void* address, size_t size) {
#if defined(V8_USE_MEMORY_SANITIZER)
MSAN_MEMORY_IS_INITIALIZED(address, size);
#elif defined(V8_USE_ADDRESS_SANITIZER)
ASAN_UNPOISON_MEMORY_REGION(address, size);
#elif DEBUG
memset(address, 0, size);
#else // Release builds.
// Nothing to be done for release builds.
#endif // Release builds.
}
V8_INLINE void SetMemoryInaccessible(void* address, size_t size) {
#if defined(V8_USE_MEMORY_SANITIZER)
memset(address, 0, size);
MSAN_ALLOCATED_UNINITIALIZED_MEMORY(address, size);
#elif defined(V8_USE_ADDRESS_SANITIZER)
NoSanitizeMemset(address, 0, size);
ASAN_POISON_MEMORY_REGION(address, size);
#elif DEBUG
::cppgc::internal::ZapMemory(address, size);
#else // Release builds.
memset(address, 0, size);
#endif // Release builds.
}
constexpr bool CheckMemoryIsInaccessibleIsNoop() {
#if defined(V8_USE_MEMORY_SANITIZER)
return true;
#elif defined(V8_USE_ADDRESS_SANITIZER)
return false;
#elif DEBUG
return false;
#else // Release builds.
return true;
#endif // Release builds.
}
V8_INLINE void CheckMemoryIsInaccessible(const void* address, size_t size) {
#if defined(V8_USE_MEMORY_SANITIZER)
static_assert(CheckMemoryIsInaccessibleIsNoop(),
"CheckMemoryIsInaccessibleIsNoop() needs to reflect "
"CheckMemoryIsInaccessible().");
// Unable to check that memory is marked as uninitialized by MSAN.
#elif defined(V8_USE_ADDRESS_SANITIZER)
static_assert(!CheckMemoryIsInaccessibleIsNoop(),
"CheckMemoryIsInaccessibleIsNoop() needs to reflect "
"CheckMemoryIsInaccessible().");
// Only check if memory is poisoned on 64 bit, since there we make sure that
// object sizes and alignments are multiple of shadow memory granularity.
#if defined(V8_TARGET_ARCH_64_BIT)
ASAN_CHECK_WHOLE_MEMORY_REGION_IS_POISONED(address, size);
#endif
ASAN_UNPOISON_MEMORY_REGION(address, size);
CheckMemoryIsZero(address, size);
ASAN_POISON_MEMORY_REGION(address, size);
#elif DEBUG
static_assert(!CheckMemoryIsInaccessibleIsNoop(),
"CheckMemoryIsInaccessibleIsNoop() needs to reflect "
"CheckMemoryIsInaccessible().");
CheckMemoryIsZapped(address, size);
#else // Release builds.
static_assert(CheckMemoryIsInaccessibleIsNoop(),
"CheckMemoryIsInaccessibleIsNoop() needs to reflect "
"CheckMemoryIsInaccessible().");
// No check in release builds.
#endif // Release builds.
}
} // namespace internal
} // namespace cppgc
#endif // V8_HEAP_CPPGC_MEMORY_H_
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