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1 // Copyright 2014 The Chromium Authors. All rights reserved. | 1 // Copyright 2014 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #include "wtf/AddressSpaceRandomization.h" | 5 #include "wtf/AddressSpaceRandomization.h" |
6 | 6 |
7 #include "wtf/PageAllocator.h" | 7 #include "wtf/PageAllocator.h" |
8 #include "wtf/SpinLock.h" | 8 #include "wtf/SpinLock.h" |
9 | 9 |
10 #if OS(WIN) | 10 #if OS(WIN) |
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70 for (int i = 0; i < 20; ++i) { | 70 for (int i = 0; i < 20; ++i) { |
71 (void) ranvalInternal(x); | 71 (void) ranvalInternal(x); |
72 } | 72 } |
73 } | 73 } |
74 uint32_t ret = ranvalInternal(x); | 74 uint32_t ret = ranvalInternal(x); |
75 return ret; | 75 return ret; |
76 } | 76 } |
77 | 77 |
78 static struct ranctx s_ranctx; | 78 static struct ranctx s_ranctx; |
79 | 79 |
80 } | 80 } // namespace |
81 | 81 |
82 // Calculates a random preferred mapping address. In calculating an | 82 // Calculates a random preferred mapping address. In calculating an |
83 // address, we balance good ASLR against not fragmenting the address | 83 // address, we balance good ASLR against not fragmenting the address |
84 // space too badly. | 84 // space too badly. |
85 void* getRandomPageBase() | 85 void* getRandomPageBase() |
86 { | 86 { |
87 uintptr_t random; | 87 uintptr_t random; |
88 random = static_cast<uintptr_t>(ranval(&s_ranctx)); | 88 random = static_cast<uintptr_t>(ranval(&s_ranctx)); |
89 #if CPU(X86_64) | 89 #if CPU(X86_64) |
90 random <<= 32UL; | 90 random <<= 32UL; |
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123 #endif // OS(WIN) | 123 #endif // OS(WIN) |
124 // This is a good range on Windows, Linux and Mac. | 124 // This is a good range on Windows, Linux and Mac. |
125 // Allocates in the 0.5-1.5GB region. | 125 // Allocates in the 0.5-1.5GB region. |
126 random &= 0x3fffffff; | 126 random &= 0x3fffffff; |
127 random += 0x20000000; | 127 random += 0x20000000; |
128 #endif // CPU(X86_64) | 128 #endif // CPU(X86_64) |
129 random &= kPageAllocationGranularityBaseMask; | 129 random &= kPageAllocationGranularityBaseMask; |
130 return reinterpret_cast<void*>(random); | 130 return reinterpret_cast<void*>(random); |
131 } | 131 } |
132 | 132 |
133 } | 133 } // namespace WTF |
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