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// Copyright 2022 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.
#include "src/common/code-memory-access-inl.h"
namespace v8 {
namespace internal {
#if V8_HAS_PTHREAD_JIT_WRITE_PROTECT || V8_HAS_PKU_JIT_WRITE_PROTECT
thread_local int RwxMemoryWriteScope::code_space_write_nesting_level_ = 0;
#endif // V8_HAS_PTHREAD_JIT_WRITE_PROTECT || V8_HAS_PKU_JIT_WRITE_PROTECT
#if V8_HAS_PKU_JIT_WRITE_PROTECT
int RwxMemoryWriteScope::memory_protection_key_ =
base::MemoryProtectionKey::kNoMemoryProtectionKey;
#if DEBUG
thread_local bool
RwxMemoryWriteScope::is_key_permissions_initialized_for_current_thread_ =
false;
bool RwxMemoryWriteScope::pkey_initialized = false;
bool RwxMemoryWriteScope::is_key_permissions_initialized_for_current_thread() {
return is_key_permissions_initialized_for_current_thread_;
}
#endif // DEBUG
void RwxMemoryWriteScope::InitializeMemoryProtectionKey() {
// Flip {pkey_initialized} (in debug mode) and check the new value.
DCHECK_EQ(true, pkey_initialized = !pkey_initialized);
memory_protection_key_ = base::MemoryProtectionKey::AllocateKey();
DCHECK(memory_protection_key_ > 0 ||
memory_protection_key_ ==
base::MemoryProtectionKey::kNoMemoryProtectionKey);
}
bool RwxMemoryWriteScope::IsPKUWritable() {
DCHECK(pkey_initialized);
return base::MemoryProtectionKey::GetKeyPermission(memory_protection_key_) ==
base::MemoryProtectionKey::kNoRestrictions;
}
ResetPKUPermissionsForThreadSpawning::ResetPKUPermissionsForThreadSpawning() {
if (!RwxMemoryWriteScope::IsSupported()) return;
was_writable_ = RwxMemoryWriteScope::IsPKUWritable();
if (was_writable_) {
base::MemoryProtectionKey::SetPermissionsForKey(
RwxMemoryWriteScope::memory_protection_key(),
base::MemoryProtectionKey::kDisableWrite);
}
}
ResetPKUPermissionsForThreadSpawning::~ResetPKUPermissionsForThreadSpawning() {
if (!RwxMemoryWriteScope::IsSupported()) return;
if (was_writable_) {
base::MemoryProtectionKey::SetPermissionsForKey(
RwxMemoryWriteScope::memory_protection_key(),
base::MemoryProtectionKey::kNoRestrictions);
}
}
void RwxMemoryWriteScope::SetDefaultPermissionsForNewThread() {
// TODO(v8:13023): consider initializing the permissions only once per thread
// if the SetPermissionsForKey() call is too heavy.
if (RwxMemoryWriteScope::IsSupported() &&
base::MemoryProtectionKey::GetKeyPermission(
RwxMemoryWriteScope::memory_protection_key()) ==
base::MemoryProtectionKey::kDisableAccess) {
base::MemoryProtectionKey::SetPermissionsForKey(
RwxMemoryWriteScope::memory_protection_key(),
base::MemoryProtectionKey::kDisableWrite);
}
#if DEBUG
is_key_permissions_initialized_for_current_thread_ = true;
#endif
}
void RwxMemoryWriteScope::SetDefaultPermissionsForSignalHandler() {
DCHECK(pkey_initialized);
DCHECK(is_key_permissions_initialized_for_current_thread_);
if (!RwxMemoryWriteScope::IsSupported()) return;
base::MemoryProtectionKey::SetPermissionsForKey(
memory_protection_key_, base::MemoryProtectionKey::kDisableWrite);
}
#else // !V8_HAS_PKU_JIT_WRITE_PROTECT
void RwxMemoryWriteScope::SetDefaultPermissionsForNewThread() {}
#if DEBUG
bool RwxMemoryWriteScope::is_key_permissions_initialized_for_current_thread() {
return true;
}
#endif // DEBUG
#endif // V8_HAS_PKU_JIT_WRITE_PROTECT
RwxMemoryWriteScopeForTesting::RwxMemoryWriteScopeForTesting()
: RwxMemoryWriteScope("For Testing") {}
RwxMemoryWriteScopeForTesting::~RwxMemoryWriteScopeForTesting() {}
} // namespace internal
} // namespace v8
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