| // 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/flags.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(); |
| |
| 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(); } |
| intptr_t AliasOffset() const { return alias_.start() - region_.start(); } |
| |
| static void Init(); |
| static void Cleanup(); |
| |
| // Returns true if dual mapping is enabled. |
| static bool DualMappingEnabled(); |
| |
| bool Contains(uword addr) const { return region_.Contains(addr); } |
| bool ContainsAlias(uword addr) const { |
| return (AliasOffset() != 0) && alias_.Contains(addr); |
| } |
| |
| // Changes the protection of the virtual memory area. |
| static void Protect(void* address, intptr_t size, Protection mode); |
| void 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) { |
| return AllocateAligned(size, PageSize(), is_executable, name); |
| } |
| static VirtualMemory* AllocateAligned(intptr_t size, |
| intptr_t alignment, |
| bool is_executable, |
| const char* name); |
| |
| // Returns the cached page size. Use only if Init() has been called. |
| static intptr_t PageSize() { |
| ASSERT(page_size_ != 0); |
| return page_size_; |
| } |
| |
| static bool InSamePage(uword address0, uword address1); |
| |
| // Truncate this virtual memory segment. |
| void Truncate(intptr_t new_size); |
| |
| // 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); |
| |
| void release() { |
| // Make sure no pages would be leaked. |
| const uword size_ = size(); |
| ASSERT(address() == reserved_.pointer() && size_ == reserved_.size()); |
| reserved_ = MemoryRegion(nullptr, 0); |
| } |
| |
| private: |
| static intptr_t CalculatePageSize(); |
| |
| // 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(void* address, intptr_t size); |
| |
| // These constructors are only used internally when reserving new virtual |
| // spaces. They do not reserve any virtual address space on their own. |
| VirtualMemory(const MemoryRegion& region, |
| const MemoryRegion& alias, |
| const MemoryRegion& reserved) |
| : region_(region), alias_(alias), reserved_(reserved) {} |
| |
| VirtualMemory(const MemoryRegion& region, const MemoryRegion& reserved) |
| : region_(region), alias_(region), reserved_(reserved) {} |
| |
| MemoryRegion region_; |
| |
| // Optional secondary mapping of region_ to a virtual space with different |
| // protection, e.g. allowing code execution. |
| MemoryRegion alias_; |
| |
| // 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_; |
| |
| static uword page_size_; |
| |
| DISALLOW_IMPLICIT_CONSTRUCTORS(VirtualMemory); |
| }; |
| |
| } // namespace dart |
| |
| #endif // RUNTIME_VM_VIRTUAL_MEMORY_H_ |