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295f920116
I wrote a script to do this which is attached to the bug. TBR=abarth@chromium.org BUG=435361 Review URL: https://codereview.chromium.org/736373003
103 lines
4.8 KiB
C++
103 lines
4.8 KiB
C++
/*
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* Copyright (C) 2013 Google Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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*
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following disclaimer
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* in the documentation and/or other materials provided with the
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* distribution.
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* * Neither the name of Google Inc. nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef SKY_ENGINE_WTF_PAGEALLOCATOR_H_
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#define SKY_ENGINE_WTF_PAGEALLOCATOR_H_
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#include <stdint.h>
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#include "sky/engine/wtf/Assertions.h"
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#include "sky/engine/wtf/CPU.h"
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#include "sky/engine/wtf/WTFExport.h"
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namespace WTF {
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#if OS(WIN)
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static const size_t kPageAllocationGranularityShift = 16; // 64KB
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#else
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static const size_t kPageAllocationGranularityShift = 12; // 4KB
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#endif
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static const size_t kPageAllocationGranularity = 1 << kPageAllocationGranularityShift;
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static const size_t kPageAllocationGranularityOffsetMask = kPageAllocationGranularity - 1;
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static const size_t kPageAllocationGranularityBaseMask = ~kPageAllocationGranularityOffsetMask;
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// All Blink-supported systems have 4096 sized system pages and can handle
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// permissions and commit / decommit at this granularity.
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static const size_t kSystemPageSize = 4096;
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static const size_t kSystemPageOffsetMask = kSystemPageSize - 1;
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static const size_t kSystemPageBaseMask = ~kSystemPageOffsetMask;
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// Allocate one or more pages. Addresses in the range will be readable and
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// writeable but not executable.
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// The requested address is just a hint; the actual address returned may
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// differ. The returned address will be aligned at least to align bytes.
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// len is in bytes, and must be a multiple of kPageAllocationGranularity.
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// align is in bytes, and must be a power-of-two multiple of
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// kPageAllocationGranularity.
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// If addr is null, then a suitable and randomized address will be chosen
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// automatically.
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// This call will return null if the allocation cannot be satisfied.
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WTF_EXPORT void* allocPages(void* addr, size_t len, size_t align);
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// Free one or more pages.
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// addr and len must match a previous call to allocPages().
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WTF_EXPORT void freePages(void* addr, size_t len);
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// Mark one or more system pages as being inaccessible.
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// Subsequently accessing any address in the range will fault, and the
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// addresses will not be re-used by future allocations.
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// len must be a multiple of kSystemPageSize bytes.
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WTF_EXPORT void setSystemPagesInaccessible(void* addr, size_t len);
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// Mark one or more system pages as being accessible.
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// The pages will be readable and writeable.
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// len must be a multiple of kSystemPageSize bytes.
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WTF_EXPORT void setSystemPagesAccessible(void* addr, size_t len);
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// Decommit one or more system pages. Decommitted means that the physical memory
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// is released to the system, but the virtual address space remains reserved.
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// System pages are re-committed by calling recommitSystemPages(). Touching
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// a decommitted page _may_ fault.
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// Clients should not make any assumptions about the contents of decommitted
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// system pages, before or after they write to the page. The only guarantee
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// provided is that the contents of the system page will be deterministic again
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// after recommitting and writing to it. In particlar note that system pages are// not guaranteed to be zero-filled upon re-commit.
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// len must be a multiple of kSystemPageSize bytes.
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WTF_EXPORT void decommitSystemPages(void* addr, size_t len);
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// Recommit one or more system pages. Decommitted system pages must be
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// recommitted before they are read are written again.
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// Note that this operation may be a no-op on some platforms.
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// len must be a multiple of kSystemPageSize bytes.
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WTF_EXPORT void recommitSystemPages(void* addr, size_t len);
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} // namespace WTF
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#endif // SKY_ENGINE_WTF_PAGEALLOCATOR_H_
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