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page-allocator.cc
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170 lines (142 loc) · 5.33 KB
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// Copyright 2017 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/base/page-allocator.h"
#include "src/base/platform/platform.h"
#if V8_OS_DARWIN
#include <sys/mman.h> // For MAP_JIT.
#endif
namespace v8 {
namespace base {
#define STATIC_ASSERT_ENUM(a, b) \
static_assert(static_cast<int>(a) == static_cast<int>(b), \
"mismatching enum: " #a)
STATIC_ASSERT_ENUM(PageAllocator::kNoAccess,
base::OS::MemoryPermission::kNoAccess);
STATIC_ASSERT_ENUM(PageAllocator::kReadWrite,
base::OS::MemoryPermission::kReadWrite);
STATIC_ASSERT_ENUM(PageAllocator::kReadWriteExecute,
base::OS::MemoryPermission::kReadWriteExecute);
STATIC_ASSERT_ENUM(PageAllocator::kReadExecute,
base::OS::MemoryPermission::kReadExecute);
STATIC_ASSERT_ENUM(PageAllocator::kNoAccessWillJitLater,
base::OS::MemoryPermission::kNoAccessWillJitLater);
#undef STATIC_ASSERT_ENUM
PageAllocator::PageAllocator()
: allocate_page_size_(base::OS::AllocatePageSize()),
commit_page_size_(base::OS::CommitPageSize()) {}
void PageAllocator::SetRandomMmapSeed(int64_t seed) {
base::OS::SetRandomMmapSeed(seed);
}
void* PageAllocator::GetRandomMmapAddr() {
return base::OS::GetRandomMmapAddr();
}
void* PageAllocator::AllocatePages(void* hint, size_t size, size_t alignment,
PageAllocator::Permission access) {
#if !V8_HAS_PTHREAD_JIT_WRITE_PROTECT && !V8_HAS_BECORE_JIT_WRITE_PROTECT
// kNoAccessWillJitLater is only used on Apple Silicon. Map it to regular
// kNoAccess on other platforms, so code doesn't have to handle both enum
// values.
if (access == PageAllocator::kNoAccessWillJitLater) {
access = PageAllocator::kNoAccess;
}
#endif
return base::OS::Allocate(hint, size, alignment,
static_cast<base::OS::MemoryPermission>(access));
}
class SharedMemoryMapping : public ::v8::PageAllocator::SharedMemoryMapping {
public:
explicit SharedMemoryMapping(PageAllocator* page_allocator, void* ptr,
size_t size)
: page_allocator_(page_allocator), ptr_(ptr), size_(size) {}
~SharedMemoryMapping() override { page_allocator_->FreePages(ptr_, size_); }
void* GetMemory() const override { return ptr_; }
private:
PageAllocator* page_allocator_;
void* ptr_;
size_t size_;
};
class SharedMemory : public ::v8::PageAllocator::SharedMemory {
public:
SharedMemory(PageAllocator* allocator, void* memory, size_t size)
: allocator_(allocator), ptr_(memory), size_(size) {}
void* GetMemory() const override { return ptr_; }
size_t GetSize() const override { return size_; }
std::unique_ptr<::v8::PageAllocator::SharedMemoryMapping> RemapTo(
void* new_address) const override {
if (allocator_->RemapShared(ptr_, new_address, size_)) {
return std::make_unique<SharedMemoryMapping>(allocator_, new_address,
size_);
} else {
return {};
}
}
~SharedMemory() override { allocator_->FreePages(ptr_, size_); }
private:
PageAllocator* allocator_;
void* ptr_;
size_t size_;
};
bool PageAllocator::CanAllocateSharedPages() {
#ifdef V8_OS_LINUX
return true;
#else
return false;
#endif
}
std::unique_ptr<v8::PageAllocator::SharedMemory>
PageAllocator::AllocateSharedPages(size_t size, const void* original_address) {
#ifdef V8_OS_LINUX
void* ptr =
base::OS::AllocateShared(size, base::OS::MemoryPermission::kReadWrite);
CHECK_NOT_NULL(ptr);
memcpy(ptr, original_address, size);
bool success = base::OS::SetPermissions(
ptr, size, base::OS::MemoryPermission::kReadWrite);
CHECK(success);
auto shared_memory =
std::make_unique<v8::base::SharedMemory>(this, ptr, size);
return shared_memory;
#else
return {};
#endif
}
void* PageAllocator::RemapShared(void* old_address, void* new_address,
size_t size) {
#ifdef V8_OS_LINUX
return base::OS::RemapShared(old_address, new_address, size);
#else
return nullptr;
#endif
}
bool PageAllocator::FreePages(void* address, size_t size) {
base::OS::Free(address, size);
return true;
}
bool PageAllocator::ReleasePages(void* address, size_t size, size_t new_size) {
DCHECK_LT(new_size, size);
base::OS::Release(reinterpret_cast<uint8_t*>(address) + new_size,
size - new_size);
return true;
}
bool PageAllocator::SetPermissions(void* address, size_t size,
PageAllocator::Permission access) {
return base::OS::SetPermissions(
address, size, static_cast<base::OS::MemoryPermission>(access));
}
bool PageAllocator::RecommitPages(void* address, size_t size,
PageAllocator::Permission access) {
return base::OS::RecommitPages(
address, size, static_cast<base::OS::MemoryPermission>(access));
}
bool PageAllocator::DiscardSystemPages(void* address, size_t size) {
return base::OS::DiscardSystemPages(address, size);
}
bool PageAllocator::DecommitPages(void* address, size_t size) {
return base::OS::DecommitPages(address, size);
}
bool PageAllocator::SealPages(void* address, size_t size) {
return base::OS::SealPages(address, size);
}
} // namespace base
} // namespace v8