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comparison: js/src/assembler/jit/ExecutableAllocatorWin.cpp
js/src/assembler/jit/ExecutableAllocatorWin.cpp
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| 1 /* | |
| 2 * Copyright (C) 2008 Apple 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 | |
| 6 * are met: | |
| 7 * 1. Redistributions of source code must retain the above copyright | |
| 8 * notice, this list of conditions and the following disclaimer. | |
| 9 * 2. Redistributions in binary form must reproduce the above copyright | |
| 10 * notice, this list of conditions and the following disclaimer in the | |
| 11 * documentation and/or other materials provided with the distribution. | |
| 12 * | |
| 13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY | |
| 14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
| 15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR | |
| 16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR | |
| 17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, | |
| 18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, | |
| 19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR | |
| 20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY | |
| 21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
| 22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE | |
| 23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
| 24 */ | |
| 25 | |
| 26 #include "assembler/jit/ExecutableAllocator.h" | |
| 27 | |
| 28 #if ENABLE_ASSEMBLER && WTF_OS_WINDOWS | |
| 29 | |
| 30 #include "jswin.h" | |
| 31 #include "mozilla/WindowsVersion.h" | |
| 32 | |
| 33 extern uint64_t random_next(uint64_t *, int); | |
| 34 | |
| 35 namespace JSC { | |
| 36 | |
| 37 uint64_t ExecutableAllocator::rngSeed; | |
| 38 | |
| 39 size_t ExecutableAllocator::determinePageSize() | |
| 40 { | |
| 41 SYSTEM_INFO system_info; | |
| 42 GetSystemInfo(&system_info); | |
| 43 return system_info.dwPageSize; | |
| 44 } | |
| 45 | |
| 46 void *ExecutableAllocator::computeRandomAllocationAddress() | |
| 47 { | |
| 48 /* | |
| 49 * Inspiration is V8's OS::Allocate in platform-win32.cc. | |
| 50 * | |
| 51 * VirtualAlloc takes 64K chunks out of the virtual address space, so we | |
| 52 * keep 16b alignment. | |
| 53 * | |
| 54 * x86: V8 comments say that keeping addresses in the [64MiB, 1GiB) range | |
| 55 * tries to avoid system default DLL mapping space. In the end, we get 13 | |
| 56 * bits of randomness in our selection. | |
| 57 * x64: [2GiB, 4TiB), with 25 bits of randomness. | |
| 58 */ | |
| 59 static const unsigned chunkBits = 16; | |
| 60 #if WTF_CPU_X86_64 | |
| 61 static const uintptr_t base = 0x0000000080000000; | |
| 62 static const uintptr_t mask = 0x000003ffffff0000; | |
| 63 #elif WTF_CPU_X86 | |
| 64 static const uintptr_t base = 0x04000000; | |
| 65 static const uintptr_t mask = 0x3fff0000; | |
| 66 #else | |
| 67 # error "Unsupported architecture" | |
| 68 #endif | |
| 69 uint64_t rand = random_next(&rngSeed, 32) << chunkBits; | |
| 70 return (void *) (base | rand & mask); | |
| 71 } | |
| 72 | |
| 73 static bool | |
| 74 RandomizeIsBrokenImpl() | |
| 75 { | |
| 76 // We disable everything before Vista, for now. | |
| 77 return !mozilla::IsVistaOrLater(); | |
| 78 } | |
| 79 | |
| 80 static bool | |
| 81 RandomizeIsBroken() | |
| 82 { | |
| 83 // Use the compiler's intrinsic guards for |static type value = expr| to avoid some potential | |
| 84 // races if runtimes are created from multiple threads. | |
| 85 static int result = RandomizeIsBrokenImpl(); | |
| 86 return !!result; | |
| 87 } | |
| 88 | |
| 89 ExecutablePool::Allocation ExecutableAllocator::systemAlloc(size_t n) | |
| 90 { | |
| 91 void *allocation = NULL; | |
| 92 // Randomization disabled to avoid a performance fault on x64 builds. | |
| 93 // See bug 728623. | |
| 94 #ifndef JS_CPU_X64 | |
| 95 if (!RandomizeIsBroken()) { | |
| 96 void *randomAddress = computeRandomAllocationAddress(); | |
| 97 allocation = VirtualAlloc(randomAddress, n, MEM_COMMIT | MEM_RESERVE, | |
| 98 PAGE_EXECUTE_READWRITE); | |
| 99 } | |
| 100 #endif | |
| 101 if (!allocation) | |
| 102 allocation = VirtualAlloc(0, n, MEM_COMMIT | MEM_RESERVE, PAGE_EXECUTE_READWRITE); | |
| 103 ExecutablePool::Allocation alloc = { reinterpret_cast<char*>(allocation), n }; | |
| 104 return alloc; | |
| 105 } | |
| 106 | |
| 107 void ExecutableAllocator::systemRelease(const ExecutablePool::Allocation& alloc) | |
| 108 { | |
| 109 VirtualFree(alloc.pages, 0, MEM_RELEASE); | |
| 110 } | |
| 111 | |
| 112 void | |
| 113 ExecutablePool::toggleAllCodeAsAccessible(bool accessible) | |
| 114 { | |
| 115 char* begin = m_allocation.pages; | |
| 116 size_t size = m_freePtr - begin; | |
| 117 | |
| 118 if (size) { | |
| 119 // N.B. DEP is not on automatically in Windows XP, so be sure to use | |
| 120 // PAGE_NOACCESS instead of PAGE_READWRITE when making inaccessible. | |
| 121 DWORD oldProtect; | |
| 122 int flags = accessible ? PAGE_EXECUTE_READWRITE : PAGE_NOACCESS; | |
| 123 if (!VirtualProtect(begin, size, flags, &oldProtect)) | |
| 124 MOZ_CRASH(); | |
| 125 } | |
| 126 } | |
| 127 | |
| 128 #if ENABLE_ASSEMBLER_WX_EXCLUSIVE | |
| 129 #error "ASSEMBLER_WX_EXCLUSIVE not yet suported on this platform." | |
| 130 #endif | |
| 131 | |
| 132 } | |
| 133 | |
| 134 #endif // HAVE(ASSEMBLER) |
