blob: fd7c5d117739e073dad3b41d9047d717ce39deaf [file] [log] [blame]
// Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
#include "vm/globals.h"
#if defined(HOST_OS_WINDOWS)
#include "vm/virtual_memory.h"
#include "platform/assert.h"
#include "vm/os.h"
#include "vm/isolate.h"
namespace dart {
DECLARE_FLAG(bool, write_protect_code);
uword VirtualMemory::page_size_ = 0;
intptr_t VirtualMemory::CalculatePageSize() {
SYSTEM_INFO info;
GetSystemInfo(&info);
const intptr_t page_size = info.dwPageSize;
ASSERT(page_size != 0);
ASSERT(Utils::IsPowerOfTwo(page_size));
return page_size;
}
void VirtualMemory::Init() {
page_size_ = CalculatePageSize();
}
bool VirtualMemory::DualMappingEnabled() {
return false;
}
VirtualMemory* VirtualMemory::AllocateAligned(intptr_t size,
intptr_t alignment,
bool is_executable,
const char* name) {
// When FLAG_write_protect_code is active, code memory (indicated by
// is_executable = true) is allocated as non-executable and later
// changed to executable via VirtualMemory::Protect.
ASSERT(Utils::IsAligned(size, PageSize()));
ASSERT(Utils::IsPowerOfTwo(alignment));
ASSERT(Utils::IsAligned(alignment, PageSize()));
intptr_t reserved_size = size + alignment - PageSize();
int prot = (is_executable && !FLAG_write_protect_code)
? PAGE_EXECUTE_READWRITE
: PAGE_READWRITE;
void* address = VirtualAlloc(NULL, reserved_size, MEM_RESERVE, prot);
if (address == NULL) {
return NULL;
}
void* aligned_address = reinterpret_cast<void*>(
Utils::RoundUp(reinterpret_cast<uword>(address), alignment));
if (VirtualAlloc(aligned_address, size, MEM_COMMIT, prot) !=
aligned_address) {
VirtualFree(address, reserved_size, MEM_RELEASE);
return NULL;
}
MemoryRegion region(aligned_address, size);
MemoryRegion reserved(address, reserved_size);
return new VirtualMemory(region, reserved);
}
VirtualMemory::~VirtualMemory() {
// Note that the size of the reserved region might be set to 0 by
// Truncate(0, true) but that does not actually release the mapping
// itself. The only way to release the mapping is to invoke VirtualFree
// with original base pointer and MEM_RELEASE.
if (!vm_owns_region()) {
return;
}
if (VirtualFree(reserved_.pointer(), 0, MEM_RELEASE) == 0) {
FATAL1("VirtualFree failed: Error code %d\n", GetLastError());
}
}
void VirtualMemory::FreeSubSegment(void* address,
intptr_t size) {
if (VirtualFree(address, size, MEM_DECOMMIT) == 0) {
FATAL1("VirtualFree failed: Error code %d\n", GetLastError());
}
}
void VirtualMemory::Protect(void* address, intptr_t size, Protection mode) {
#if defined(DEBUG)
Thread* thread = Thread::Current();
ASSERT(thread == nullptr || thread->IsMutatorThread() ||
thread->isolate() == nullptr ||
thread->isolate()->mutator_thread()->IsAtSafepoint());
#endif
uword start_address = reinterpret_cast<uword>(address);
uword end_address = start_address + size;
uword page_address = Utils::RoundDown(start_address, PageSize());
DWORD prot = 0;
switch (mode) {
case kNoAccess:
prot = PAGE_NOACCESS;
break;
case kReadOnly:
prot = PAGE_READONLY;
break;
case kReadWrite:
prot = PAGE_READWRITE;
break;
case kReadExecute:
prot = PAGE_EXECUTE_READ;
break;
case kReadWriteExecute:
prot = PAGE_EXECUTE_READWRITE;
break;
}
DWORD old_prot = 0;
if (VirtualProtect(reinterpret_cast<void*>(page_address),
end_address - page_address, prot, &old_prot) == 0) {
FATAL1("VirtualProtect failed %d\n", GetLastError());
}
}
} // namespace dart
#endif // defined(HOST_OS_WINDOWS)