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