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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/allocator/PageAllocator.h" | |
| 32 | |
| 33 #include "wtf/Assertions.h" | |
| 34 #include "wtf/Atomics.h" | |
| 35 #include "wtf/allocator/AddressSpaceRandomization.h" | |
| 36 | |
| 37 #include <limits.h> | |
| 38 | |
| 39 #if OS(POSIX) | |
| 40 | |
| 41 #include <errno.h> | |
| 42 #include <sys/mman.h> | |
| 43 | |
| 44 #ifndef MADV_FREE | |
| 45 #define MADV_FREE MADV_DONTNEED | |
| 46 #endif | |
| 47 | |
| 48 #ifndef MAP_ANONYMOUS | |
| 49 #define MAP_ANONYMOUS MAP_ANON | |
| 50 #endif | |
| 51 | |
| 52 // On POSIX memmap uses a nearby address if the hint address is blocked. | |
| 53 static const bool kHintIsAdvisory = true; | |
| 54 static uint32_t s_allocPageErrorCode = 0; | |
| 55 | |
| 56 #elif OS(WIN) | |
| 57 | |
| 58 #include <windows.h> | |
| 59 | |
| 60 // VirtualAlloc will fail if allocation at the hint address is blocked. | |
| 61 static const bool kHintIsAdvisory = false; | |
| 62 static uint32_t s_allocPageErrorCode = ERROR_SUCCESS; | |
| 63 | |
| 64 #else | |
| 65 #error Unknown OS | |
| 66 #endif // OS(POSIX) | |
| 67 | |
| 68 namespace WTF { | |
| 69 | |
| 70 // This internal function wraps the OS-specific page allocation call. The | |
| 71 // behavior of the hint address is determined by the kHintIsAdvisory constant. | |
| 72 // If true, a non-zero hint is advisory and the returned address may differ from | |
| 73 // the hint. If false, the hint is mandatory and a successful allocation will | |
| 74 // not differ from the hint. | |
| 75 static void* systemAllocPages( | |
| 76 void* hint, | |
| 77 size_t len, | |
| 78 PageAccessibilityConfiguration pageAccessibility) { | |
| 79 ASSERT(!(len & kPageAllocationGranularityOffsetMask)); | |
| 80 ASSERT(!(reinterpret_cast<uintptr_t>(hint) & | |
| 81 kPageAllocationGranularityOffsetMask)); | |
| 82 void* ret; | |
| 83 #if OS(WIN) | |
| 84 DWORD accessFlag = | |
| 85 pageAccessibility == PageAccessible ? PAGE_READWRITE : PAGE_NOACCESS; | |
| 86 ret = VirtualAlloc(hint, len, MEM_RESERVE | MEM_COMMIT, accessFlag); | |
| 87 if (!ret) | |
| 88 releaseStore(&s_allocPageErrorCode, GetLastError()); | |
| 89 #else | |
| 90 int accessFlag = pageAccessibility == PageAccessible | |
| 91 ? (PROT_READ | PROT_WRITE) | |
| 92 : PROT_NONE; | |
| 93 ret = mmap(hint, len, accessFlag, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0); | |
| 94 if (ret == MAP_FAILED) { | |
| 95 releaseStore(&s_allocPageErrorCode, errno); | |
| 96 ret = 0; | |
| 97 } | |
| 98 #endif | |
| 99 return ret; | |
| 100 } | |
| 101 | |
| 102 // Trims base to given length and alignment. Windows returns null on failure and | |
| 103 // frees base. | |
| 104 static void* trimMapping(void* base, | |
| 105 size_t baseLen, | |
| 106 size_t trimLen, | |
| 107 uintptr_t align, | |
| 108 PageAccessibilityConfiguration pageAccessibility) { | |
| 109 size_t preSlack = reinterpret_cast<uintptr_t>(base) & (align - 1); | |
| 110 if (preSlack) | |
| 111 preSlack = align - preSlack; | |
| 112 size_t postSlack = baseLen - preSlack - trimLen; | |
| 113 ASSERT(baseLen >= trimLen || preSlack || postSlack); | |
| 114 ASSERT(preSlack < baseLen); | |
| 115 ASSERT(postSlack < baseLen); | |
| 116 void* ret = base; | |
| 117 | |
| 118 #if OS(POSIX) // On POSIX we can resize the allocation run. | |
| 119 (void)pageAccessibility; | |
| 120 if (preSlack) { | |
| 121 int res = munmap(base, preSlack); | |
| 122 RELEASE_ASSERT(!res); | |
| 123 ret = reinterpret_cast<char*>(base) + preSlack; | |
| 124 } | |
| 125 if (postSlack) { | |
| 126 int res = munmap(reinterpret_cast<char*>(ret) + trimLen, postSlack); | |
| 127 RELEASE_ASSERT(!res); | |
| 128 } | |
| 129 #else // On Windows we can't resize the allocation run. | |
| 130 if (preSlack || postSlack) { | |
| 131 ret = reinterpret_cast<char*>(base) + preSlack; | |
| 132 freePages(base, baseLen); | |
| 133 ret = systemAllocPages(ret, trimLen, pageAccessibility); | |
| 134 } | |
| 135 #endif | |
| 136 | |
| 137 return ret; | |
| 138 } | |
| 139 | |
| 140 void* allocPages(void* addr, | |
| 141 size_t len, | |
| 142 size_t align, | |
| 143 PageAccessibilityConfiguration pageAccessibility) { | |
| 144 ASSERT(len >= kPageAllocationGranularity); | |
| 145 ASSERT(!(len & kPageAllocationGranularityOffsetMask)); | |
| 146 ASSERT(align >= kPageAllocationGranularity); | |
| 147 ASSERT(!(align & kPageAllocationGranularityOffsetMask)); | |
| 148 ASSERT(!(reinterpret_cast<uintptr_t>(addr) & | |
| 149 kPageAllocationGranularityOffsetMask)); | |
| 150 uintptr_t alignOffsetMask = align - 1; | |
| 151 uintptr_t alignBaseMask = ~alignOffsetMask; | |
| 152 ASSERT(!(reinterpret_cast<uintptr_t>(addr) & alignOffsetMask)); | |
| 153 | |
| 154 // If the client passed null as the address, choose a good one. | |
| 155 if (!addr) { | |
| 156 addr = getRandomPageBase(); | |
| 157 addr = reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(addr) & | |
| 158 alignBaseMask); | |
| 159 } | |
| 160 | |
| 161 // First try to force an exact-size, aligned allocation from our random base. | |
| 162 for (int count = 0; count < 3; ++count) { | |
| 163 void* ret = systemAllocPages(addr, len, pageAccessibility); | |
| 164 if (kHintIsAdvisory || ret) { | |
| 165 // If the alignment is to our liking, we're done. | |
| 166 if (!(reinterpret_cast<uintptr_t>(ret) & alignOffsetMask)) | |
| 167 return ret; | |
| 168 freePages(ret, len); | |
| 169 #if CPU(32BIT) | |
| 170 addr = reinterpret_cast<void*>( | |
| 171 (reinterpret_cast<uintptr_t>(ret) + align) & alignBaseMask); | |
| 172 #endif | |
| 173 } else if (!addr) { // We know we're OOM when an unhinted allocation fails. | |
| 174 return nullptr; | |
| 175 | |
| 176 } else { | |
| 177 #if CPU(32BIT) | |
| 178 addr = reinterpret_cast<char*>(addr) + align; | |
| 179 #endif | |
| 180 } | |
| 181 | |
| 182 #if !CPU(32BIT) | |
| 183 // Keep trying random addresses on systems that have a large address space. | |
| 184 addr = getRandomPageBase(); | |
| 185 addr = reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(addr) & | |
| 186 alignBaseMask); | |
| 187 #endif | |
| 188 } | |
| 189 | |
| 190 // Map a larger allocation so we can force alignment, but continue randomizing | |
| 191 // only on 64-bit POSIX. | |
| 192 size_t tryLen = len + (align - kPageAllocationGranularity); | |
| 193 RELEASE_ASSERT(tryLen >= len); | |
| 194 void* ret; | |
| 195 | |
| 196 do { | |
| 197 // Don't continue to burn cycles on mandatory hints (Windows). | |
| 198 addr = kHintIsAdvisory ? getRandomPageBase() : nullptr; | |
| 199 ret = systemAllocPages(addr, tryLen, pageAccessibility); | |
| 200 // The retries are for Windows, where a race can steal our mapping on | |
| 201 // resize. | |
| 202 } while (ret && | |
| 203 !(ret = trimMapping(ret, tryLen, len, align, pageAccessibility))); | |
| 204 | |
| 205 return ret; | |
| 206 } | |
| 207 | |
| 208 void freePages(void* addr, size_t len) { | |
| 209 ASSERT(!(reinterpret_cast<uintptr_t>(addr) & | |
| 210 kPageAllocationGranularityOffsetMask)); | |
| 211 ASSERT(!(len & kPageAllocationGranularityOffsetMask)); | |
| 212 #if OS(POSIX) | |
| 213 int ret = munmap(addr, len); | |
| 214 RELEASE_ASSERT(!ret); | |
| 215 #else | |
| 216 BOOL ret = VirtualFree(addr, 0, MEM_RELEASE); | |
| 217 RELEASE_ASSERT(ret); | |
| 218 #endif | |
| 219 } | |
| 220 | |
| 221 void setSystemPagesInaccessible(void* addr, size_t len) { | |
| 222 ASSERT(!(len & kSystemPageOffsetMask)); | |
| 223 #if OS(POSIX) | |
| 224 int ret = mprotect(addr, len, PROT_NONE); | |
| 225 RELEASE_ASSERT(!ret); | |
| 226 #else | |
| 227 BOOL ret = VirtualFree(addr, len, MEM_DECOMMIT); | |
| 228 RELEASE_ASSERT(ret); | |
| 229 #endif | |
| 230 } | |
| 231 | |
| 232 bool setSystemPagesAccessible(void* addr, size_t len) { | |
| 233 ASSERT(!(len & kSystemPageOffsetMask)); | |
| 234 #if OS(POSIX) | |
| 235 return !mprotect(addr, len, PROT_READ | PROT_WRITE); | |
| 236 #else | |
| 237 return !!VirtualAlloc(addr, len, MEM_COMMIT, PAGE_READWRITE); | |
| 238 #endif | |
| 239 } | |
| 240 | |
| 241 void decommitSystemPages(void* addr, size_t len) { | |
| 242 ASSERT(!(len & kSystemPageOffsetMask)); | |
| 243 #if OS(POSIX) | |
| 244 int ret = madvise(addr, len, MADV_FREE); | |
| 245 RELEASE_ASSERT(!ret); | |
| 246 #else | |
| 247 setSystemPagesInaccessible(addr, len); | |
| 248 #endif | |
| 249 } | |
| 250 | |
| 251 void recommitSystemPages(void* addr, size_t len) { | |
| 252 ASSERT(!(len & kSystemPageOffsetMask)); | |
| 253 #if OS(POSIX) | |
| 254 (void)addr; | |
| 255 #else | |
| 256 RELEASE_ASSERT(setSystemPagesAccessible(addr, len)); | |
| 257 #endif | |
| 258 } | |
| 259 | |
| 260 void discardSystemPages(void* addr, size_t len) { | |
| 261 ASSERT(!(len & kSystemPageOffsetMask)); | |
| 262 #if OS(POSIX) | |
| 263 // On POSIX, the implementation detail is that discard and decommit are the | |
| 264 // same, and lead to pages that are returned to the system immediately and | |
| 265 // get replaced with zeroed pages when touched. So we just call | |
| 266 // decommitSystemPages() here to avoid code duplication. | |
| 267 decommitSystemPages(addr, len); | |
| 268 #else | |
| 269 // On Windows discarded pages are not returned to the system immediately and | |
| 270 // not guaranteed to be zeroed when returned to the application. | |
| 271 using DiscardVirtualMemoryFunction = | |
| 272 DWORD(WINAPI*)(PVOID virtualAddress, SIZE_T size); | |
| 273 static DiscardVirtualMemoryFunction discardVirtualMemory = | |
| 274 reinterpret_cast<DiscardVirtualMemoryFunction>(-1); | |
| 275 if (discardVirtualMemory == | |
| 276 reinterpret_cast<DiscardVirtualMemoryFunction>(-1)) | |
| 277 discardVirtualMemory = | |
| 278 reinterpret_cast<DiscardVirtualMemoryFunction>(GetProcAddress( | |
| 279 GetModuleHandle(L"Kernel32.dll"), "DiscardVirtualMemory")); | |
| 280 // Use DiscardVirtualMemory when available because it releases faster than | |
| 281 // MEM_RESET. | |
| 282 DWORD ret = 1; | |
| 283 if (discardVirtualMemory) | |
| 284 ret = discardVirtualMemory(addr, len); | |
| 285 // DiscardVirtualMemory is buggy in Win10 SP0, so fall back to MEM_RESET on | |
| 286 // failure. | |
| 287 if (ret) { | |
| 288 void* ret = VirtualAlloc(addr, len, MEM_RESET, PAGE_READWRITE); | |
| 289 RELEASE_ASSERT(ret); | |
| 290 } | |
| 291 #endif | |
| 292 } | |
| 293 | |
| 294 uint32_t getAllocPageErrorCode() { | |
| 295 return acquireLoad(&s_allocPageErrorCode); | |
| 296 } | |
| 297 | |
| 298 } // namespace WTF | |
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Chromium Code Reviews
Issue 2518253002:
Move Partition Allocator into Chromium base. (Closed)
