dart-sdk/runtime/vm/virtual_memory_win.cc
Ryan Macnak b247090c9e [vm] Align old-space pages.
Allows quick access to the page header for any old-space object, which is a convenient place to keep forwarding information.

Also combine the reserve and commit operations of VirtualMemory.

Bug: https://github.com/dart-lang/sdk/issues/30978
Change-Id: Id3fe06932f7bef882bb1cc29d72441b0a3602eb6
Reviewed-on: https://dart-review.googlesource.com/17046
Reviewed-by: Erik Corry <erikcorry@google.com>
Reviewed-by: Zach Anderson <zra@google.com>
2017-10-30 22:02:20 +00:00

115 lines
3.5 KiB
C++

// 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 {
uword VirtualMemory::page_size_ = 0;
void VirtualMemory::InitOnce() {
SYSTEM_INFO info;
GetSystemInfo(&info);
page_size_ = info.dwPageSize;
}
VirtualMemory* VirtualMemory::Allocate(intptr_t size,
bool is_executable,
const char* name) {
ASSERT(Utils::IsAligned(size, page_size_));
int prot = is_executable ? PAGE_EXECUTE_READWRITE : PAGE_READWRITE;
void* address = VirtualAlloc(NULL, size, MEM_RESERVE | MEM_COMMIT, prot);
if (address == NULL) {
return NULL;
}
MemoryRegion region(address, size);
return new VirtualMemory(region, region);
}
VirtualMemory* VirtualMemory::AllocateAligned(intptr_t size,
intptr_t alignment,
bool is_executable,
const char* name) {
ASSERT(Utils::IsAligned(size, page_size_));
ASSERT(Utils::IsAligned(alignment, page_size_));
intptr_t reserved_size = size + alignment;
int prot = is_executable ? 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() {
if (!vm_owns_region() || (reserved_.size() == 0)) {
return;
}
if (VirtualFree(reserved_.pointer(), 0, MEM_RELEASE) == 0) {
FATAL("VirtualFree failed");
}
}
bool VirtualMemory::FreeSubSegment(int32_t handle,
void* address,
intptr_t size) {
// On Windows only the entire segment returned by VirtualAlloc
// can be freed. Therefore we will have to waste these unused
// virtual memory sub-segments.
return false;
}
bool VirtualMemory::Protect(void* address, intptr_t size, Protection mode) {
ASSERT(Thread::Current()->IsMutatorThread() ||
Isolate::Current()->mutator_thread()->IsAtSafepoint());
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;
bool result = VirtualProtect(reinterpret_cast<void*>(page_address),
end_address - page_address, prot, &old_prot);
return result;
}
} // namespace dart
#endif // defined(HOST_OS_WINDOWS)