Ryan Macnak
b247090c9e
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>
100 lines
3.3 KiB
C++
100 lines
3.3 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.
|
|
|
|
#ifndef RUNTIME_VM_VIRTUAL_MEMORY_H_
|
|
#define RUNTIME_VM_VIRTUAL_MEMORY_H_
|
|
|
|
#include "platform/utils.h"
|
|
#include "vm/globals.h"
|
|
#include "vm/memory_region.h"
|
|
|
|
namespace dart {
|
|
|
|
class VirtualMemory {
|
|
public:
|
|
enum Protection {
|
|
kNoAccess,
|
|
kReadOnly,
|
|
kReadWrite,
|
|
kReadExecute,
|
|
kReadWriteExecute
|
|
};
|
|
|
|
// The reserved memory is unmapped on destruction.
|
|
~VirtualMemory();
|
|
|
|
int32_t handle() const { return handle_; }
|
|
uword start() const { return region_.start(); }
|
|
uword end() const { return region_.end(); }
|
|
void* address() const { return region_.pointer(); }
|
|
intptr_t size() const { return region_.size(); }
|
|
|
|
static void InitOnce();
|
|
|
|
bool Contains(uword addr) const { return region_.Contains(addr); }
|
|
|
|
// Changes the protection of the virtual memory area.
|
|
static bool Protect(void* address, intptr_t size, Protection mode);
|
|
bool Protect(Protection mode) { return Protect(address(), size(), mode); }
|
|
|
|
// Reserves and commits a virtual memory segment with size. If a segment of
|
|
// the requested size cannot be allocated, NULL is returned.
|
|
static VirtualMemory* Allocate(intptr_t size,
|
|
bool is_executable,
|
|
const char* name);
|
|
static VirtualMemory* AllocateAligned(intptr_t size,
|
|
intptr_t alignment,
|
|
bool is_executable,
|
|
const char* name);
|
|
|
|
static intptr_t PageSize() {
|
|
ASSERT(page_size_ != 0);
|
|
ASSERT(Utils::IsPowerOfTwo(page_size_));
|
|
return page_size_;
|
|
}
|
|
|
|
static bool InSamePage(uword address0, uword address1);
|
|
|
|
// Truncate this virtual memory segment. If try_unmap is false, the
|
|
// memory beyond the new end is still accessible, but will be returned
|
|
// upon destruction.
|
|
void Truncate(intptr_t new_size, bool try_unmap = true);
|
|
|
|
// False for a part of a snapshot added directly to the Dart heap, which
|
|
// belongs to the embedder and must not be deallocated or have its
|
|
// protection status changed by the VM.
|
|
bool vm_owns_region() const { return reserved_.pointer() != NULL; }
|
|
|
|
static VirtualMemory* ForImagePage(void* pointer, uword size);
|
|
|
|
private:
|
|
// Free a sub segment. On operating systems that support it this
|
|
// can give back the virtual memory to the system. Returns true on success.
|
|
static bool FreeSubSegment(int32_t handle, void* address, intptr_t size);
|
|
|
|
// This constructor is only used internally when reserving new virtual spaces.
|
|
// It does not reserve any virtual address space on its own.
|
|
VirtualMemory(const MemoryRegion& region,
|
|
const MemoryRegion& reserved,
|
|
int32_t handle = 0)
|
|
: region_(region), reserved_(reserved), handle_(handle) {}
|
|
|
|
MemoryRegion region_;
|
|
|
|
// The underlying reservation not yet given back to the OS.
|
|
// Its address might disagree with region_ due to aligned allocations.
|
|
// Its size might disagree with region_ due to Truncate.
|
|
MemoryRegion reserved_;
|
|
|
|
int32_t handle_;
|
|
|
|
static uword page_size_;
|
|
|
|
DISALLOW_IMPLICIT_CONSTRUCTORS(VirtualMemory);
|
|
};
|
|
|
|
} // namespace dart
|
|
|
|
#endif // RUNTIME_VM_VIRTUAL_MEMORY_H_
|