libsanitizer/asan/asan_mapping.h

   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 0x004000000000 (e.g. when prelink is installed):
  34 // || `[0x10007fff8000, 0x7fffffffffff]` || HighMem    ||
  35 // || `[0x02008fff7000, 0x10007fff7fff]` || HighShadow ||
  36 // || `[0x004000000000, 0x02008fff6fff]` || ShadowGap3 ||
  37 // || `[0x003000000000, 0x003fffffffff]` || MidMem     ||
  38 // || `[0x00087fff8000, 0x002fffffffff]` || ShadowGap2 ||
  39 // || `[0x00067fff8000, 0x00087fff7fff]` || 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 =    0x3fffffffffULL;
 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