The Tor Browser / file comparison
comparison: js/src/yarr/OSAllocatorPosix.cpp
js/src/yarr/OSAllocatorPosix.cpp
- branch
- TOR_BUG_3246
- changeset 5
- 4ab42b5ab56c
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| -1:000000000000 | 0:42584bd75459 |
|---|---|
| 1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- | |
| 2 * vim: set ts=8 sts=4 et sw=4 tw=99: | |
| 3 * | |
| 4 * ***** BEGIN LICENSE BLOCK ***** | |
| 5 * Copyright (C) 2010 Apple Inc. All rights reserved. | |
| 6 * | |
| 7 * Redistribution and use in source and binary forms, with or without | |
| 8 * modification, are permitted provided that the following conditions | |
| 9 * are met: | |
| 10 * 1. Redistributions of source code must retain the above copyright | |
| 11 * notice, this list of conditions and the following disclaimer. | |
| 12 * 2. Redistributions in binary form must reproduce the above copyright | |
| 13 * notice, this list of conditions and the following disclaimer in the | |
| 14 * documentation and/or other materials provided with the distribution. | |
| 15 * | |
| 16 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' | |
| 17 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, | |
| 18 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR | |
| 19 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS | |
| 20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR | |
| 21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF | |
| 22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS | |
| 23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN | |
| 24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | |
| 25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF | |
| 26 * THE POSSIBILITY OF SUCH DAMAGE. | |
| 27 * | |
| 28 * ***** END LICENSE BLOCK ***** */ | |
| 29 | |
| 30 #include "assembler/wtf/Platform.h" | |
| 31 | |
| 32 #if WTF_OS_UNIX && !WTF_OS_SYMBIAN | |
| 33 | |
| 34 #include "yarr/OSAllocator.h" | |
| 35 | |
| 36 #include <errno.h> | |
| 37 #include <sys/mman.h> | |
| 38 #include "assembler/wtf/Assertions.h" | |
| 39 | |
| 40 namespace WTF { | |
| 41 | |
| 42 void* OSAllocator::reserveUncommitted(size_t bytes, Usage usage, bool writable, bool executable) | |
| 43 { | |
| 44 void* result = reserveAndCommit(bytes, usage, writable, executable); | |
| 45 #if HAVE_MADV_FREE_REUSE | |
| 46 // To support the "reserve then commit" model, we have to initially decommit. | |
| 47 while (madvise(result, bytes, MADV_FREE_REUSABLE) == -1 && errno == EAGAIN) { } | |
| 48 #endif | |
| 49 return result; | |
| 50 } | |
| 51 | |
| 52 void* OSAllocator::reserveAndCommit(size_t bytes, Usage usage, bool writable, bool executable) | |
| 53 { | |
| 54 // All POSIX reservations start out logically committed. | |
| 55 int protection = PROT_READ; | |
| 56 if (writable) | |
| 57 protection |= PROT_WRITE; | |
| 58 if (executable) | |
| 59 protection |= PROT_EXEC; | |
| 60 | |
| 61 int flags = MAP_PRIVATE | MAP_ANON; | |
| 62 | |
| 63 #if WTF_OS_DARWIN && !defined(BUILDING_ON_TIGER) | |
| 64 int fd = usage; | |
| 65 #else | |
| 66 int fd = -1; | |
| 67 #endif | |
| 68 | |
| 69 void* result = 0; | |
| 70 #if (WTF_OS_DARWIN && WTF_CPU_X86_64) | |
| 71 if (executable) { | |
| 72 // Cook up an address to allocate at, using the following recipe: | |
| 73 // 17 bits of zero, stay in userspace kids. | |
| 74 // 26 bits of randomness for ASLR. | |
| 75 // 21 bits of zero, at least stay aligned within one level of the pagetables. | |
| 76 // | |
| 77 // But! - as a temporary workaround for some plugin problems (rdar://problem/6812854), | |
| 78 // for now instead of 2^26 bits of ASLR lets stick with 25 bits of randomization plus | |
| 79 // 2^24, which should put up somewhere in the middle of userspace (in the address range | |
| 80 // 0x200000000000 .. 0x5fffffffffff). | |
| 81 intptr_t randomLocation = 0; | |
| 82 randomLocation = arc4random() & ((1 << 25) - 1); | |
| 83 randomLocation += (1 << 24); | |
| 84 randomLocation <<= 21; | |
| 85 result = reinterpret_cast<void*>(randomLocation); | |
| 86 } | |
| 87 #endif | |
| 88 | |
| 89 result = mmap(result, bytes, protection, flags, fd, 0); | |
| 90 if (result == MAP_FAILED) | |
| 91 CRASH(); | |
| 92 return result; | |
| 93 } | |
| 94 | |
| 95 void OSAllocator::commit(void* address, size_t bytes, bool, bool) | |
| 96 { | |
| 97 #if HAVE_MADV_FREE_REUSE | |
| 98 while (madvise(address, bytes, MADV_FREE_REUSE) == -1 && errno == EAGAIN) { } | |
| 99 #else | |
| 100 // Non-MADV_FREE_REUSE reservations automatically commit on demand. | |
| 101 UNUSED_PARAM(address); | |
| 102 UNUSED_PARAM(bytes); | |
| 103 #endif | |
| 104 } | |
| 105 | |
| 106 void OSAllocator::decommit(void* address, size_t bytes) | |
| 107 { | |
| 108 #if HAVE_MADV_FREE_REUSE | |
| 109 while (madvise(address, bytes, MADV_FREE_REUSABLE) == -1 && errno == EAGAIN) { } | |
| 110 #elif HAVE_MADV_FREE | |
| 111 while (madvise(address, bytes, MADV_FREE) == -1 && errno == EAGAIN) { } | |
| 112 #elif HAVE_MADV_DONTNEED | |
| 113 while (madvise(address, bytes, MADV_DONTNEED) == -1 && errno == EAGAIN) { } | |
| 114 #else | |
| 115 UNUSED_PARAM(address); | |
| 116 UNUSED_PARAM(bytes); | |
| 117 #endif | |
| 118 } | |
| 119 | |
| 120 void OSAllocator::releaseDecommitted(void* address, size_t bytes) | |
| 121 { | |
| 122 int result = munmap(address, bytes); | |
| 123 if (result == -1) | |
| 124 CRASH(); | |
| 125 } | |
| 126 | |
| 127 } // namespace WTF | |
| 128 | |
| 129 #endif |
