1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/js/src/assembler/jit/ExecutableAllocatorWin.cpp Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,134 @@
1.4 +/*
1.5 + * Copyright (C) 2008 Apple Inc. All rights reserved.
1.6 + *
1.7 + * Redistribution and use in source and binary forms, with or without
1.8 + * modification, are permitted provided that the following conditions
1.9 + * are met:
1.10 + * 1. Redistributions of source code must retain the above copyright
1.11 + * notice, this list of conditions and the following disclaimer.
1.12 + * 2. Redistributions in binary form must reproduce the above copyright
1.13 + * notice, this list of conditions and the following disclaimer in the
1.14 + * documentation and/or other materials provided with the distribution.
1.15 + *
1.16 + * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
1.17 + * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
1.18 + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
1.19 + * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
1.20 + * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
1.21 + * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
1.22 + * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
1.23 + * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
1.24 + * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
1.25 + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
1.26 + * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
1.27 + */
1.28 +
1.29 +#include "assembler/jit/ExecutableAllocator.h"
1.30 +
1.31 +#if ENABLE_ASSEMBLER && WTF_OS_WINDOWS
1.32 +
1.33 +#include "jswin.h"
1.34 +#include "mozilla/WindowsVersion.h"
1.35 +
1.36 +extern uint64_t random_next(uint64_t *, int);
1.37 +
1.38 +namespace JSC {
1.39 +
1.40 +uint64_t ExecutableAllocator::rngSeed;
1.41 +
1.42 +size_t ExecutableAllocator::determinePageSize()
1.43 +{
1.44 + SYSTEM_INFO system_info;
1.45 + GetSystemInfo(&system_info);
1.46 + return system_info.dwPageSize;
1.47 +}
1.48 +
1.49 +void *ExecutableAllocator::computeRandomAllocationAddress()
1.50 +{
1.51 + /*
1.52 + * Inspiration is V8's OS::Allocate in platform-win32.cc.
1.53 + *
1.54 + * VirtualAlloc takes 64K chunks out of the virtual address space, so we
1.55 + * keep 16b alignment.
1.56 + *
1.57 + * x86: V8 comments say that keeping addresses in the [64MiB, 1GiB) range
1.58 + * tries to avoid system default DLL mapping space. In the end, we get 13
1.59 + * bits of randomness in our selection.
1.60 + * x64: [2GiB, 4TiB), with 25 bits of randomness.
1.61 + */
1.62 + static const unsigned chunkBits = 16;
1.63 +#if WTF_CPU_X86_64
1.64 + static const uintptr_t base = 0x0000000080000000;
1.65 + static const uintptr_t mask = 0x000003ffffff0000;
1.66 +#elif WTF_CPU_X86
1.67 + static const uintptr_t base = 0x04000000;
1.68 + static const uintptr_t mask = 0x3fff0000;
1.69 +#else
1.70 +# error "Unsupported architecture"
1.71 +#endif
1.72 + uint64_t rand = random_next(&rngSeed, 32) << chunkBits;
1.73 + return (void *) (base | rand & mask);
1.74 +}
1.75 +
1.76 +static bool
1.77 +RandomizeIsBrokenImpl()
1.78 +{
1.79 + // We disable everything before Vista, for now.
1.80 + return !mozilla::IsVistaOrLater();
1.81 +}
1.82 +
1.83 +static bool
1.84 +RandomizeIsBroken()
1.85 +{
1.86 + // Use the compiler's intrinsic guards for |static type value = expr| to avoid some potential
1.87 + // races if runtimes are created from multiple threads.
1.88 + static int result = RandomizeIsBrokenImpl();
1.89 + return !!result;
1.90 +}
1.91 +
1.92 +ExecutablePool::Allocation ExecutableAllocator::systemAlloc(size_t n)
1.93 +{
1.94 + void *allocation = NULL;
1.95 + // Randomization disabled to avoid a performance fault on x64 builds.
1.96 + // See bug 728623.
1.97 +#ifndef JS_CPU_X64
1.98 + if (!RandomizeIsBroken()) {
1.99 + void *randomAddress = computeRandomAllocationAddress();
1.100 + allocation = VirtualAlloc(randomAddress, n, MEM_COMMIT | MEM_RESERVE,
1.101 + PAGE_EXECUTE_READWRITE);
1.102 + }
1.103 +#endif
1.104 + if (!allocation)
1.105 + allocation = VirtualAlloc(0, n, MEM_COMMIT | MEM_RESERVE, PAGE_EXECUTE_READWRITE);
1.106 + ExecutablePool::Allocation alloc = { reinterpret_cast<char*>(allocation), n };
1.107 + return alloc;
1.108 +}
1.109 +
1.110 +void ExecutableAllocator::systemRelease(const ExecutablePool::Allocation& alloc)
1.111 +{
1.112 + VirtualFree(alloc.pages, 0, MEM_RELEASE);
1.113 +}
1.114 +
1.115 +void
1.116 +ExecutablePool::toggleAllCodeAsAccessible(bool accessible)
1.117 +{
1.118 + char* begin = m_allocation.pages;
1.119 + size_t size = m_freePtr - begin;
1.120 +
1.121 + if (size) {
1.122 + // N.B. DEP is not on automatically in Windows XP, so be sure to use
1.123 + // PAGE_NOACCESS instead of PAGE_READWRITE when making inaccessible.
1.124 + DWORD oldProtect;
1.125 + int flags = accessible ? PAGE_EXECUTE_READWRITE : PAGE_NOACCESS;
1.126 + if (!VirtualProtect(begin, size, flags, &oldProtect))
1.127 + MOZ_CRASH();
1.128 + }
1.129 +}
1.130 +
1.131 +#if ENABLE_ASSEMBLER_WX_EXCLUSIVE
1.132 +#error "ASSEMBLER_WX_EXCLUSIVE not yet suported on this platform."
1.133 +#endif
1.134 +
1.135 +}
1.136 +
1.137 +#endif // HAVE(ASSEMBLER)
