Ben Konyi
07852532e3
Change-Id: I6dc02b3d9de16cc176eb97613bc0c7f0bb9b16eb Reviewed-on: https://dart-review.googlesource.com/77013 Commit-Queue: Ben Konyi <bkonyi@google.com> Commit-Queue: Ryan Macnak <rmacnak@google.com> Reviewed-by: Ryan Macnak <rmacnak@google.com> Auto-Submit: Ben Konyi <bkonyi@google.com>
96 lines
3.2 KiB
C++
96 lines
3.2 KiB
C++
// Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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#ifndef RUNTIME_VM_VIRTUAL_MEMORY_H_
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#define RUNTIME_VM_VIRTUAL_MEMORY_H_
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#include "platform/utils.h"
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#include "vm/globals.h"
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#include "vm/memory_region.h"
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namespace dart {
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class VirtualMemory {
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public:
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enum Protection {
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kNoAccess,
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kReadOnly,
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kReadWrite,
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kReadExecute,
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kReadWriteExecute
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};
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// The reserved memory is unmapped on destruction.
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~VirtualMemory();
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uword start() const { return region_.start(); }
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uword end() const { return region_.end(); }
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void* address() const { return region_.pointer(); }
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intptr_t size() const { return region_.size(); }
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static void Init();
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bool Contains(uword addr) const { return region_.Contains(addr); }
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// Changes the protection of the virtual memory area.
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static void Protect(void* address, intptr_t size, Protection mode);
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void Protect(Protection mode) { return Protect(address(), size(), mode); }
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// Reserves and commits a virtual memory segment with size. If a segment of
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// the requested size cannot be allocated, NULL is returned.
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static VirtualMemory* Allocate(intptr_t size,
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bool is_executable,
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const char* name);
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static VirtualMemory* AllocateAligned(intptr_t size,
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intptr_t alignment,
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bool is_executable,
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const char* name);
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static intptr_t PageSize() {
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ASSERT(page_size_ != 0);
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ASSERT(Utils::IsPowerOfTwo(page_size_));
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return page_size_;
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}
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static bool InSamePage(uword address0, uword address1);
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// Truncate this virtual memory segment. If try_unmap is false, the
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// memory beyond the new end is still accessible, but will be returned
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// upon destruction.
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void Truncate(intptr_t new_size, bool try_unmap = true);
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// False for a part of a snapshot added directly to the Dart heap, which
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// belongs to the embedder and must not be deallocated or have its
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// protection status changed by the VM.
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bool vm_owns_region() const { return reserved_.pointer() != NULL; }
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static VirtualMemory* ForImagePage(void* pointer, uword size);
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private:
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// Free a sub segment. On operating systems that support it this
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// can give back the virtual memory to the system. Returns true on success.
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static bool FreeSubSegment(void* address, intptr_t size);
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// This constructor is only used internally when reserving new virtual spaces.
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// It does not reserve any virtual address space on its own.
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VirtualMemory(const MemoryRegion& region,
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const MemoryRegion& reserved)
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: region_(region), reserved_(reserved) {}
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MemoryRegion region_;
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// The underlying reservation not yet given back to the OS.
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// Its address might disagree with region_ due to aligned allocations.
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// Its size might disagree with region_ due to Truncate.
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MemoryRegion reserved_;
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static uword page_size_;
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DISALLOW_IMPLICIT_CONSTRUCTORS(VirtualMemory);
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};
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} // namespace dart
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#endif // RUNTIME_VM_VIRTUAL_MEMORY_H_
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