1/* 2 * Copyright (C) 2013 Google Inc. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions are 6 * met: 7 * 8 * * Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * * Redistributions in binary form must reproduce the above 11 * copyright notice, this list of conditions and the following disclaimer 12 * in the documentation and/or other materials provided with the 13 * distribution. 14 * * Neither the name of Google Inc. nor the names of its 15 * contributors may be used to endorse or promote products derived from 16 * this software without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 */ 30 31#ifndef WTF_PageAllocator_h 32#define WTF_PageAllocator_h 33 34#include "wtf/Assertions.h" 35#include "wtf/CPU.h" 36#include "wtf/WTFExport.h" 37#include <stdint.h> 38 39namespace WTF { 40 41#if OS(WIN) 42static const size_t kPageAllocationGranularityShift = 16; // 64KB 43#else 44static const size_t kPageAllocationGranularityShift = 12; // 4KB 45#endif 46static const size_t kPageAllocationGranularity = 1 << kPageAllocationGranularityShift; 47static const size_t kPageAllocationGranularityOffsetMask = kPageAllocationGranularity - 1; 48static const size_t kPageAllocationGranularityBaseMask = ~kPageAllocationGranularityOffsetMask; 49 50// All Blink-supported systems have 4096 sized system pages and can handle 51// permissions and commit / decommit at this granularity. 52static const size_t kSystemPageSize = 4096; 53static const size_t kSystemPageOffsetMask = kSystemPageSize - 1; 54static const size_t kSystemPageBaseMask = ~kSystemPageOffsetMask; 55 56// Allocate one or more pages. Addresses in the range will be readable and 57// writeable but not executable. 58// The requested address is just a hint; the actual address returned may 59// differ. The returned address will be aligned at least to align bytes. 60// len is in bytes, and must be a multiple of kPageAllocationGranularity. 61// align is in bytes, and must be a power-of-two multiple of 62// kPageAllocationGranularity. 63// If addr is null, then a suitable and randomized address will be chosen 64// automatically. 65// This call will return null if the allocation cannot be satisfied. 66WTF_EXPORT void* allocPages(void* addr, size_t len, size_t align); 67 68// Free one or more pages. 69// addr and len must match a previous call to allocPages(). 70WTF_EXPORT void freePages(void* addr, size_t len); 71 72// Mark one or more system pages as being inaccessible. 73// Subsequently accessing any address in the range will fault, and the 74// addresses will not be re-used by future allocations. 75// len must be a multiple of kSystemPageSize bytes. 76WTF_EXPORT void setSystemPagesInaccessible(void* addr, size_t len); 77 78// Mark one or more system pages as being accessible. 79// The pages will be readable and writeable. 80// len must be a multiple of kSystemPageSize bytes. 81WTF_EXPORT void setSystemPagesAccessible(void* addr, size_t len); 82 83// Decommit one or more system pages. Decommitted means that the physical memory 84// is released to the system, but the virtual address space remains reserved. 85// System pages are re-committed by calling recommitSystemPages(). Touching 86// a decommitted page _may_ fault. 87// Clients should not make any assumptions about the contents of decommitted 88// system pages, before or after they write to the page. The only guarantee 89// provided is that the contents of the system page will be deterministic again 90// after recommitting and writing to it. In particlar note that system pages are// not guaranteed to be zero-filled upon re-commit. 91// len must be a multiple of kSystemPageSize bytes. 92WTF_EXPORT void decommitSystemPages(void* addr, size_t len); 93 94// Recommit one or more system pages. Decommitted system pages must be 95// recommitted before they are read are written again. 96// Note that this operation may be a no-op on some platforms. 97// len must be a multiple of kSystemPageSize bytes. 98WTF_EXPORT void recommitSystemPages(void* addr, size_t len); 99 100} // namespace WTF 101 102#endif // WTF_PageAllocator_h 103