1 //===-- asan_mapping.h ------------------------------------------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file is a part of AddressSanitizer, an address sanity checker. 11 // 12 // Defines ASan memory mapping. 13 //===----------------------------------------------------------------------===// 14 #ifndef ASAN_MAPPING_H 15 #define ASAN_MAPPING_H 16 17 #include "asan_internal.h" 18 19 // The full explanation of the memory mapping could be found here: 20 // http://code.google.com/p/address-sanitizer/wiki/AddressSanitizerAlgorithm 21 // 22 // Typical shadow mapping on Linux/x86_64 with SHADOW_OFFSET == 0x00007fff8000: 23 // || `[0x10007fff8000, 0x7fffffffffff]` || HighMem || 24 // || `[0x02008fff7000, 0x10007fff7fff]` || HighShadow || 25 // || `[0x00008fff7000, 0x02008fff6fff]` || ShadowGap || 26 // || `[0x00007fff8000, 0x00008fff6fff]` || LowShadow || 27 // || `[0x000000000000, 0x00007fff7fff]` || LowMem || 28 // 29 // When SHADOW_OFFSET is zero (-pie): 30 // || `[0x100000000000, 0x7fffffffffff]` || HighMem || 31 // || `[0x020000000000, 0x0fffffffffff]` || HighShadow || 32 // || `[0x000000040000, 0x01ffffffffff]` || ShadowGap || 33 // 34 // Special case when something is already mapped between 35 // 0x003000000000 and 0x005000000000 (e.g. when prelink is installed): 36 // || `[0x10007fff8000, 0x7fffffffffff]` || HighMem || 37 // || `[0x02008fff7000, 0x10007fff7fff]` || HighShadow || 38 // || `[0x005000000000, 0x02008fff6fff]` || ShadowGap3 || 39 // || `[0x003000000000, 0x004fffffffff]` || MidMem || 40 // || `[0x000a7fff8000, 0x002fffffffff]` || ShadowGap2 || 41 // || `[0x00067fff8000, 0x000a7fff7fff]` || MidShadow || 42 // || `[0x00008fff7000, 0x00067fff7fff]` || ShadowGap || 43 // || `[0x00007fff8000, 0x00008fff6fff]` || LowShadow || 44 // || `[0x000000000000, 0x00007fff7fff]` || LowMem || 45 // 46 // Default Linux/i386 mapping: 47 // || `[0x40000000, 0xffffffff]` || HighMem || 48 // || `[0x28000000, 0x3fffffff]` || HighShadow || 49 // || `[0x24000000, 0x27ffffff]` || ShadowGap || 50 // || `[0x20000000, 0x23ffffff]` || LowShadow || 51 // || `[0x00000000, 0x1fffffff]` || LowMem || 52 53 #if ASAN_FLEXIBLE_MAPPING_AND_OFFSET == 1 54 extern SANITIZER_INTERFACE_ATTRIBUTE uptr __asan_mapping_scale; 55 extern SANITIZER_INTERFACE_ATTRIBUTE uptr __asan_mapping_offset; 56 # define SHADOW_SCALE (__asan_mapping_scale) 57 # define SHADOW_OFFSET (__asan_mapping_offset) 58 #else 59 # if ASAN_ANDROID 60 # define SHADOW_SCALE (3) 61 # define SHADOW_OFFSET (0) 62 # else 63 # define SHADOW_SCALE (3) 64 # if SANITIZER_WORDSIZE == 32 65 # define SHADOW_OFFSET (1 << 29) 66 # else 67 # if defined(__powerpc64__) 68 # define SHADOW_OFFSET (1ULL << 41) 69 # else 70 # if ASAN_MAC 71 # define SHADOW_OFFSET (1ULL << 44) 72 # else 73 # define SHADOW_OFFSET 0x7fff8000ULL 74 # endif 75 # endif 76 # endif 77 # endif 78 #endif // ASAN_FLEXIBLE_MAPPING_AND_OFFSET 79 80 #define SHADOW_GRANULARITY (1ULL << SHADOW_SCALE) 81 #define MEM_TO_SHADOW(mem) (((mem) >> SHADOW_SCALE) + (SHADOW_OFFSET)) 82 #define SHADOW_TO_MEM(shadow) (((shadow) - SHADOW_OFFSET) << SHADOW_SCALE) 83 84 #define kLowMemBeg 0 85 #define kLowMemEnd (SHADOW_OFFSET ? SHADOW_OFFSET - 1 : 0) 86 87 #define kLowShadowBeg SHADOW_OFFSET 88 #define kLowShadowEnd MEM_TO_SHADOW(kLowMemEnd) 89 90 #define kHighMemBeg (MEM_TO_SHADOW(kHighMemEnd) + 1) 91 92 #define kHighShadowBeg MEM_TO_SHADOW(kHighMemBeg) 93 #define kHighShadowEnd MEM_TO_SHADOW(kHighMemEnd) 94 95 # define kMidShadowBeg MEM_TO_SHADOW(kMidMemBeg) 96 # define kMidShadowEnd MEM_TO_SHADOW(kMidMemEnd) 97 98 // With the zero shadow base we can not actually map pages starting from 0. 99 // This constant is somewhat arbitrary. 100 #define kZeroBaseShadowStart (1 << 18) 101 102 #define kShadowGapBeg (kLowShadowEnd ? kLowShadowEnd + 1 \ 103 : kZeroBaseShadowStart) 104 #define kShadowGapEnd ((kMidMemBeg ? kMidShadowBeg : kHighShadowBeg) - 1) 105 106 #define kShadowGap2Beg (kMidMemBeg ? kMidShadowEnd + 1 : 0) 107 #define kShadowGap2End (kMidMemBeg ? kMidMemBeg - 1 : 0) 108 109 #define kShadowGap3Beg (kMidMemBeg ? kMidMemEnd + 1 : 0) 110 #define kShadowGap3End (kMidMemBeg ? kHighShadowBeg - 1 : 0) 111 112 #define DO_ASAN_MAPPING_PROFILE 0 // Set to 1 to profile the functions below. 113 114 #if DO_ASAN_MAPPING_PROFILE 115 # define PROFILE_ASAN_MAPPING() AsanMappingProfile[__LINE__]++; 116 #else 117 # define PROFILE_ASAN_MAPPING() 118 #endif 119 120 // If 1, all shadow boundaries are constants. 121 // Don't set to 1 other than for testing. 122 #define ASAN_FIXED_MAPPING 0 123 124 namespace __asan { 125 126 extern uptr AsanMappingProfile[]; 127 128 #if ASAN_FIXED_MAPPING 129 // Fixed mapping for 64-bit Linux. Mostly used for performance comparison 130 // with non-fixed mapping. As of r175253 (Feb 2013) the performance 131 // difference between fixed and non-fixed mapping is below the noise level. 132 static uptr kHighMemEnd = 0x7fffffffffffULL; 133 static uptr kMidMemBeg = 0x3000000000ULL; 134 static uptr kMidMemEnd = 0x4fffffffffULL; 135 #else 136 SANITIZER_INTERFACE_ATTRIBUTE 137 extern uptr kHighMemEnd, kMidMemBeg, kMidMemEnd; // Initialized in __asan_init. 138 #endif 139 140 static inline bool AddrIsInLowMem(uptr a) { 141 PROFILE_ASAN_MAPPING(); 142 return a < kLowMemEnd; 143 } 144 145 static inline bool AddrIsInLowShadow(uptr a) { 146 PROFILE_ASAN_MAPPING(); 147 return a >= kLowShadowBeg && a <= kLowShadowEnd; 148 } 149 150 static inline bool AddrIsInHighMem(uptr a) { 151 PROFILE_ASAN_MAPPING(); 152 return a >= kHighMemBeg && a <= kHighMemEnd; 153 } 154 155 static inline bool AddrIsInMidMem(uptr a) { 156 PROFILE_ASAN_MAPPING(); 157 return kMidMemBeg && a >= kMidMemBeg && a <= kMidMemEnd; 158 } 159 160 static inline bool AddrIsInMem(uptr a) { 161 PROFILE_ASAN_MAPPING(); 162 return AddrIsInLowMem(a) || AddrIsInMidMem(a) || AddrIsInHighMem(a); 163 } 164 165 static inline uptr MemToShadow(uptr p) { 166 PROFILE_ASAN_MAPPING(); 167 CHECK(AddrIsInMem(p)); 168 return MEM_TO_SHADOW(p); 169 } 170 171 static inline bool AddrIsInHighShadow(uptr a) { 172 PROFILE_ASAN_MAPPING(); 173 return a >= kHighShadowBeg && a <= kHighMemEnd; 174 } 175 176 static inline bool AddrIsInMidShadow(uptr a) { 177 PROFILE_ASAN_MAPPING(); 178 return kMidMemBeg && a >= kMidShadowBeg && a <= kMidMemEnd; 179 } 180 181 static inline bool AddrIsInShadow(uptr a) { 182 PROFILE_ASAN_MAPPING(); 183 return AddrIsInLowShadow(a) || AddrIsInMidShadow(a) || AddrIsInHighShadow(a); 184 } 185 186 static inline bool AddrIsInShadowGap(uptr a) { 187 PROFILE_ASAN_MAPPING(); 188 if (kMidMemBeg) { 189 if (a <= kShadowGapEnd) 190 return SHADOW_OFFSET == 0 || a >= kShadowGapBeg; 191 return (a >= kShadowGap2Beg && a <= kShadowGap2End) || 192 (a >= kShadowGap3Beg && a <= kShadowGap3End); 193 } 194 // In zero-based shadow mode we treat addresses near zero as addresses 195 // in shadow gap as well. 196 if (SHADOW_OFFSET == 0) 197 return a <= kShadowGapEnd; 198 return a >= kShadowGapBeg && a <= kShadowGapEnd; 199 } 200 201 static inline bool AddrIsAlignedByGranularity(uptr a) { 202 PROFILE_ASAN_MAPPING(); 203 return (a & (SHADOW_GRANULARITY - 1)) == 0; 204 } 205 206 static inline bool AddressIsPoisoned(uptr a) { 207 PROFILE_ASAN_MAPPING(); 208 const uptr kAccessSize = 1; 209 u8 *shadow_address = (u8*)MEM_TO_SHADOW(a); 210 s8 shadow_value = *shadow_address; 211 if (shadow_value) { 212 u8 last_accessed_byte = (a & (SHADOW_GRANULARITY - 1)) 213 + kAccessSize - 1; 214 return (last_accessed_byte >= shadow_value); 215 } 216 return false; 217 } 218 219 // Must be after all calls to PROFILE_ASAN_MAPPING(). 220 static const uptr kAsanMappingProfileSize = __LINE__; 221 222 } // namespace __asan 223 224 #endif // ASAN_MAPPING_H 225
