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| 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 #include "wtf/PageAllocator.h" | |
| 32 | |
| 33 #include "wtf/AddressSpaceRandomization.h" | |
| 34 #include "wtf/Assertions.h" | |
| 35 | |
| 36 #include <limits.h> | |
| 37 | |
| 38 #if OS(POSIX) | |
| 39 | |
| 40 #include <errno.h> | |
| 41 #include <sys/mman.h> | |
| 42 | |
| 43 #ifndef MADV_FREE | |
| 44 #define MADV_FREE MADV_DONTNEED | |
| 45 #endif | |
| 46 | |
| 47 #ifndef MAP_ANONYMOUS | |
| 48 #define MAP_ANONYMOUS MAP_ANON | |
| 49 #endif | |
| 50 | |
| 51 // On POSIX memmap uses a nearby address if the hint address is blocked. | |
| 52 static const bool kHintIsAdvisory = true; | |
| 53 static uint32_t allocPageErrorCode = 0; | |
| 54 | |
| 55 #elif OS(WIN) | |
| 56 | |
| 57 #include <windows.h> | |
| 58 | |
| 59 // VirtualAlloc will fail if allocation at the hint address is blocked. | |
| 60 static const bool kHintIsAdvisory = false; | |
| 61 static uint32_t allocPageErrorCode = ERROR_SUCCESS; | |
| 62 | |
| 63 #else | |
| 64 #error Unknown OS | |
| 65 #endif // OS(POSIX) | |
| 66 | |
| 67 namespace WTF { | |
| 68 | |
| 69 // This internal function wraps the OS-specific page allocation call. The | |
| 70 // behavior of the hint address is determined by the kHintIsAdvisory constant. | |
| 71 // If true, a non-zero hint is advisory and the returned address may differ from | |
| 72 // the hint. If false, the hint is mandatory and a successful allocation will | |
| 73 // not differ from the hint. | |
| 74 static void* systemAllocPages(void* hint, size_t len, PageAccessibilityConfigura
tion pageAccessibility) | |
| 75 { | |
| 76 ASSERT(!(len & kPageAllocationGranularityOffsetMask)); | |
| 77 ASSERT(!(reinterpret_cast<uintptr_t>(hint) & kPageAllocationGranularityOffse
tMask)); | |
| 78 void* ret; | |
| 79 #if OS(WIN) | |
| 80 DWORD accessFlag = pageAccessibility == PageAccessible ? PAGE_READWRITE : PA
GE_NOACCESS; | |
| 81 ret = VirtualAlloc(hint, len, MEM_RESERVE | MEM_COMMIT, accessFlag); | |
| 82 if (!ret) | |
| 83 allocPageErrorCode = GetLastError(); | |
| 84 #else | |
| 85 int accessFlag = pageAccessibility == PageAccessible ? (PROT_READ | PROT_WRI
TE) : PROT_NONE; | |
| 86 ret = mmap(hint, len, accessFlag, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0); | |
| 87 if (ret == MAP_FAILED) { | |
| 88 allocPageErrorCode = errno; | |
| 89 ret = 0; | |
| 90 } | |
| 91 #endif | |
| 92 return ret; | |
| 93 } | |
| 94 | |
| 95 // Trims base to given length and alignment. Windows returns null on failure and
frees base. | |
| 96 static void* trimMapping(void *base, size_t baseLen, size_t trimLen, uintptr_t a
lign, PageAccessibilityConfiguration pageAccessibility) | |
| 97 { | |
| 98 size_t preSlack = reinterpret_cast<uintptr_t>(base) & (align - 1); | |
| 99 if (preSlack) | |
| 100 preSlack = align - preSlack; | |
| 101 size_t postSlack = baseLen - preSlack - trimLen; | |
| 102 ASSERT(baseLen >= trimLen || preSlack || postSlack); | |
| 103 ASSERT(preSlack < baseLen); | |
| 104 ASSERT(postSlack < baseLen); | |
| 105 void* ret = base; | |
| 106 | |
| 107 #if OS(POSIX) // On POSIX we can resize the allocation run. | |
| 108 (void) pageAccessibility; | |
| 109 if (preSlack) { | |
| 110 int res = munmap(base, preSlack); | |
| 111 RELEASE_ASSERT(!res); | |
| 112 ret = reinterpret_cast<char*>(base) + preSlack; | |
| 113 } | |
| 114 if (postSlack) { | |
| 115 int res = munmap(reinterpret_cast<char*>(ret) + trimLen, postSlack); | |
| 116 RELEASE_ASSERT(!res); | |
| 117 } | |
| 118 #else // On Windows we can't resize the allocation run. | |
| 119 if (preSlack || postSlack) { | |
| 120 ret = reinterpret_cast<char*>(base) + preSlack; | |
| 121 freePages(base, baseLen); | |
| 122 ret = systemAllocPages(ret, trimLen, pageAccessibility); | |
| 123 } | |
| 124 #endif | |
| 125 | |
| 126 return ret; | |
| 127 } | |
| 128 | |
| 129 void* allocPages(void* addr, size_t len, size_t align, PageAccessibilityConfigur
ation pageAccessibility) | |
| 130 { | |
| 131 ASSERT(len >= kPageAllocationGranularity); | |
| 132 ASSERT(!(len & kPageAllocationGranularityOffsetMask)); | |
| 133 ASSERT(align >= kPageAllocationGranularity); | |
| 134 ASSERT(!(align & kPageAllocationGranularityOffsetMask)); | |
| 135 ASSERT(!(reinterpret_cast<uintptr_t>(addr) & kPageAllocationGranularityOffse
tMask)); | |
| 136 uintptr_t alignOffsetMask = align - 1; | |
| 137 uintptr_t alignBaseMask = ~alignOffsetMask; | |
| 138 ASSERT(!(reinterpret_cast<uintptr_t>(addr) & alignOffsetMask)); | |
| 139 | |
| 140 // If the client passed null as the address, choose a good one. | |
| 141 if (!addr) { | |
| 142 addr = getRandomPageBase(); | |
| 143 addr = reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(addr) & align
BaseMask); | |
| 144 } | |
| 145 | |
| 146 // First try to force an exact-size, aligned allocation from our random base
. | |
| 147 for (int count = 0; count < 3; ++count) { | |
| 148 void* ret = systemAllocPages(addr, len, pageAccessibility); | |
| 149 if (kHintIsAdvisory || ret) { | |
| 150 // If the alignment is to our liking, we're done. | |
| 151 if (!(reinterpret_cast<uintptr_t>(ret)& alignOffsetMask)) | |
| 152 return ret; | |
| 153 freePages(ret, len); | |
| 154 #if CPU(32BIT) | |
| 155 addr = reinterpret_cast<void*>((reinterpret_cast<uintptr_t>(ret)+ali
gn) & alignBaseMask); | |
| 156 #endif | |
| 157 } else if (!addr) { // We know we're OOM when an unhinted allocation fai
ls. | |
| 158 return nullptr; | |
| 159 | |
| 160 } else { | |
| 161 #if CPU(32BIT) | |
| 162 addr = reinterpret_cast<char*>(addr) + align; | |
| 163 #endif | |
| 164 } | |
| 165 | |
| 166 #if !CPU(32BIT) // Keep trying random addresses on systems that have a large add
ress space. | |
| 167 addr = getRandomPageBase(); | |
| 168 addr = reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(addr) & align
BaseMask); | |
| 169 #endif | |
| 170 } | |
| 171 | |
| 172 // Map a larger allocation so we can force alignment, but continue randomizi
ng only on 64-bit POSIX. | |
| 173 size_t tryLen = len + (align - kPageAllocationGranularity); | |
| 174 RELEASE_ASSERT(tryLen >= len); | |
| 175 void* ret; | |
| 176 | |
| 177 do { | |
| 178 // Don't continue to burn cycles on mandatory hints (Windows). | |
| 179 addr = kHintIsAdvisory ? getRandomPageBase() : nullptr; | |
| 180 ret = systemAllocPages(addr, tryLen, pageAccessibility); | |
| 181 // The retries are for Windows, where a race can steal our mapping on resize
. | |
| 182 } while (ret && !(ret = trimMapping(ret, tryLen, len, align, pageAccessibili
ty))); | |
| 183 | |
| 184 return ret; | |
| 185 } | |
| 186 | |
| 187 void freePages(void* addr, size_t len) | |
| 188 { | |
| 189 ASSERT(!(reinterpret_cast<uintptr_t>(addr) & kPageAllocationGranularityOffse
tMask)); | |
| 190 ASSERT(!(len & kPageAllocationGranularityOffsetMask)); | |
| 191 #if OS(POSIX) | |
| 192 int ret = munmap(addr, len); | |
| 193 RELEASE_ASSERT(!ret); | |
| 194 #else | |
| 195 BOOL ret = VirtualFree(addr, 0, MEM_RELEASE); | |
| 196 RELEASE_ASSERT(ret); | |
| 197 #endif | |
| 198 } | |
| 199 | |
| 200 void setSystemPagesInaccessible(void* addr, size_t len) | |
| 201 { | |
| 202 ASSERT(!(len & kSystemPageOffsetMask)); | |
| 203 #if OS(POSIX) | |
| 204 int ret = mprotect(addr, len, PROT_NONE); | |
| 205 RELEASE_ASSERT(!ret); | |
| 206 #else | |
| 207 BOOL ret = VirtualFree(addr, len, MEM_DECOMMIT); | |
| 208 RELEASE_ASSERT(ret); | |
| 209 #endif | |
| 210 } | |
| 211 | |
| 212 bool setSystemPagesAccessible(void* addr, size_t len) | |
| 213 { | |
| 214 ASSERT(!(len & kSystemPageOffsetMask)); | |
| 215 #if OS(POSIX) | |
| 216 return !mprotect(addr, len, PROT_READ | PROT_WRITE); | |
| 217 #else | |
| 218 return !!VirtualAlloc(addr, len, MEM_COMMIT, PAGE_READWRITE); | |
| 219 #endif | |
| 220 } | |
| 221 | |
| 222 void decommitSystemPages(void* addr, size_t len) | |
| 223 { | |
| 224 ASSERT(!(len & kSystemPageOffsetMask)); | |
| 225 #if OS(POSIX) | |
| 226 int ret = madvise(addr, len, MADV_FREE); | |
| 227 RELEASE_ASSERT(!ret); | |
| 228 #else | |
| 229 setSystemPagesInaccessible(addr, len); | |
| 230 #endif | |
| 231 } | |
| 232 | |
| 233 void recommitSystemPages(void* addr, size_t len) | |
| 234 { | |
| 235 ASSERT(!(len & kSystemPageOffsetMask)); | |
| 236 #if OS(POSIX) | |
| 237 (void) addr; | |
| 238 #else | |
| 239 RELEASE_ASSERT(setSystemPagesAccessible(addr, len)); | |
| 240 #endif | |
| 241 } | |
| 242 | |
| 243 void discardSystemPages(void* addr, size_t len) | |
| 244 { | |
| 245 ASSERT(!(len & kSystemPageOffsetMask)); | |
| 246 #if OS(POSIX) | |
| 247 // On POSIX, the implementation detail is that discard and decommit are the | |
| 248 // same, and lead to pages that are returned to the system immediately and | |
| 249 // get replaced with zeroed pages when touched. So we just call | |
| 250 // decommitSystemPages() here to avoid code duplication. | |
| 251 decommitSystemPages(addr, len); | |
| 252 #else | |
| 253 // On Windows discarded pages are not returned to the system immediately and | |
| 254 // not guaranteed to be zeroed when returned to the application. | |
| 255 using DiscardVirtualMemoryFunction = DWORD(WINAPI*)(PVOID virtualAddress, SI
ZE_T size); | |
| 256 static DiscardVirtualMemoryFunction discardVirtualMemory = reinterpret_cast<
DiscardVirtualMemoryFunction>(-1); | |
| 257 if (discardVirtualMemory == reinterpret_cast<DiscardVirtualMemoryFunction>(-
1)) | |
| 258 discardVirtualMemory = reinterpret_cast<DiscardVirtualMemoryFunction>(Ge
tProcAddress(GetModuleHandle(L"Kernel32.dll"), "DiscardVirtualMemory")); | |
| 259 // Use DiscardVirtualMemory when available because it releases faster than M
EM_RESET. | |
| 260 DWORD ret = 1; | |
| 261 if (discardVirtualMemory) | |
| 262 ret = discardVirtualMemory(addr, len); | |
| 263 // DiscardVirtualMemory is buggy in Win10 SP0, so fall back to MEM_RESET on
failure. | |
| 264 if (ret) { | |
| 265 void* ret = VirtualAlloc(addr, len, MEM_RESET, PAGE_READWRITE); | |
| 266 RELEASE_ASSERT(ret); | |
| 267 } | |
| 268 #endif | |
| 269 } | |
| 270 | |
| 271 uint32_t getAllocPageErrorCode() | |
| 272 { | |
| 273 return allocPageErrorCode; | |
| 274 } | |
| 275 | |
| 276 } // namespace WTF | |
| 277 | |
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Chromium Code Reviews
Issue 1881983003:
Move PartitionAlloc related things into wtf/allocator. (Closed)
Base URL: https://chromium.googlesource.com/chromium/src.git@master