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 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 // Default Linux/MIPS mapping:
  52 // || `[0x2aaa8000, 0xffffffff]` || HighMem    ||
  53 // || `[0x0fffd000, 0x2aaa7fff]` || HighShadow ||
  54 // || `[0x0bffd000, 0x0fffcfff]` || ShadowGap  ||
  55 // || `[0x0aaa8000, 0x0bffcfff]` || LowShadow  ||
  56 // || `[0x00000000, 0x0aaa7fff]` || LowMem     ||
  57
  58 static const u64 kDefaultShadowScale = 3;
  59 static const u64 kDefaultShadowOffset32 = 1ULL << 29;
  60 static const u64 kDefaultShadowOffset64 = 1ULL << 44;
  61 static const u64 kDefaultShort64bitShadowOffset = 0x7FFF8000;  // < 2G.
  62 static const u64 kPPC64_ShadowOffset64 = 1ULL << 41;
  63 static const u64 kMIPS32_ShadowOffset32 = 0x0aaa8000;
  64
  65 #if ASAN_FLEXIBLE_MAPPING_AND_OFFSET == 1
  66 extern SANITIZER_INTERFACE_ATTRIBUTE uptr __asan_mapping_scale;
  67 extern SANITIZER_INTERFACE_ATTRIBUTE uptr __asan_mapping_offset;
  68 # define SHADOW_SCALE (__asan_mapping_scale)
  69 # define SHADOW_OFFSET (__asan_mapping_offset)
  70 #else
  71 # define SHADOW_SCALE kDefaultShadowScale
  72 # if SANITIZER_ANDROID
  73 #  define SHADOW_OFFSET (0)
  74 # else
  75 #  if SANITIZER_WORDSIZE == 32
  76 #   if defined(__mips__)
  77 #     define SHADOW_OFFSET kMIPS32_ShadowOffset32
  78 #   else
  79 #     define SHADOW_OFFSET kDefaultShadowOffset32
  80 #   endif
  81 #  else
  82 #   if defined(__powerpc64__)
  83 #    define SHADOW_OFFSET kPPC64_ShadowOffset64
  84 #   elif SANITIZER_MAC
  85 #    define SHADOW_OFFSET kDefaultShadowOffset64
  86 #   else
  87 #    define SHADOW_OFFSET kDefaultShort64bitShadowOffset
  88 #   endif
  89 #  endif
  90 # endif
  91 #endif  // ASAN_FLEXIBLE_MAPPING_AND_OFFSET
  92
  93 #define SHADOW_GRANULARITY (1ULL << SHADOW_SCALE)
  94 #define MEM_TO_SHADOW(mem) (((mem) >> SHADOW_SCALE) + (SHADOW_OFFSET))
  95 #define SHADOW_TO_MEM(shadow) (((shadow) - SHADOW_OFFSET) << SHADOW_SCALE)
  96
  97 #define kLowMemBeg      0
  98 #define kLowMemEnd      (SHADOW_OFFSET ? SHADOW_OFFSET - 1 : 0)
  99
 100 #define kLowShadowBeg   SHADOW_OFFSET
 101 #define kLowShadowEnd   MEM_TO_SHADOW(kLowMemEnd)
 102
 103 #define kHighMemBeg     (MEM_TO_SHADOW(kHighMemEnd) + 1)
 104
 105 #define kHighShadowBeg  MEM_TO_SHADOW(kHighMemBeg)
 106 #define kHighShadowEnd  MEM_TO_SHADOW(kHighMemEnd)
 107
 108 # define kMidShadowBeg MEM_TO_SHADOW(kMidMemBeg)
 109 # define kMidShadowEnd MEM_TO_SHADOW(kMidMemEnd)
 110
 111 // With the zero shadow base we can not actually map pages starting from 0.
 112 // This constant is somewhat arbitrary.
 113 #define kZeroBaseShadowStart (1 << 18)
 114
 115 #define kShadowGapBeg   (kLowShadowEnd ? kLowShadowEnd + 1 \
 116                                        : kZeroBaseShadowStart)
 117 #define kShadowGapEnd   ((kMidMemBeg ? kMidShadowBeg : kHighShadowBeg) - 1)
 118
 119 #define kShadowGap2Beg (kMidMemBeg ? kMidShadowEnd + 1 : 0)
 120 #define kShadowGap2End (kMidMemBeg ? kMidMemBeg - 1 : 0)
 121
 122 #define kShadowGap3Beg (kMidMemBeg ? kMidMemEnd + 1 : 0)
 123 #define kShadowGap3End (kMidMemBeg ? kHighShadowBeg - 1 : 0)
 124
 125 #define DO_ASAN_MAPPING_PROFILE 0  // Set to 1 to profile the functions below.
 126
 127 #if DO_ASAN_MAPPING_PROFILE
 128 # define PROFILE_ASAN_MAPPING() AsanMappingProfile[__LINE__]++;
 129 #else
 130 # define PROFILE_ASAN_MAPPING()
 131 #endif
 132
 133 // If 1, all shadow boundaries are constants.
 134 // Don't set to 1 other than for testing.
 135 #define ASAN_FIXED_MAPPING 0
 136
 137 namespace __asan {
 138
 139 extern uptr AsanMappingProfile[];
 140
 141 #if ASAN_FIXED_MAPPING
 142 // Fixed mapping for 64-bit Linux. Mostly used for performance comparison
 143 // with non-fixed mapping. As of r175253 (Feb 2013) the performance
 144 // difference between fixed and non-fixed mapping is below the noise level.
 145 static uptr kHighMemEnd = 0x7fffffffffffULL;
 146 static uptr kMidMemBeg =    0x3000000000ULL;
 147 static uptr kMidMemEnd =    0x4fffffffffULL;
 148 #else
 149 extern uptr kHighMemEnd, kMidMemBeg, kMidMemEnd;  // Initialized in __asan_init.
 150 #endif
 151
 152 static inline bool AddrIsInLowMem(uptr a) {
 153   PROFILE_ASAN_MAPPING();
 154   return a < kLowMemEnd;
 155 }
 156
 157 static inline bool AddrIsInLowShadow(uptr a) {
 158   PROFILE_ASAN_MAPPING();
 159   return a >= kLowShadowBeg && a <= kLowShadowEnd;
 160 }
 161
 162 static inline bool AddrIsInHighMem(uptr a) {
 163   PROFILE_ASAN_MAPPING();
 164   return a >= kHighMemBeg && a <= kHighMemEnd;
 165 }
 166
 167 static inline bool AddrIsInMidMem(uptr a) {
 168   PROFILE_ASAN_MAPPING();
 169   return kMidMemBeg && a >= kMidMemBeg && a <= kMidMemEnd;
 170 }
 171
 172 static inline bool AddrIsInMem(uptr a) {
 173   PROFILE_ASAN_MAPPING();
 174   return AddrIsInLowMem(a) || AddrIsInMidMem(a) || AddrIsInHighMem(a);
 175 }
 176
 177 static inline uptr MemToShadow(uptr p) {
 178   PROFILE_ASAN_MAPPING();
 179   CHECK(AddrIsInMem(p));
 180   return MEM_TO_SHADOW(p);
 181 }
 182
 183 static inline bool AddrIsInHighShadow(uptr a) {
 184   PROFILE_ASAN_MAPPING();
 185   return a >= kHighShadowBeg && a <= kHighMemEnd;
 186 }
 187
 188 static inline bool AddrIsInMidShadow(uptr a) {
 189   PROFILE_ASAN_MAPPING();
 190   return kMidMemBeg && a >= kMidShadowBeg && a <= kMidMemEnd;
 191 }
 192
 193 static inline bool AddrIsInShadow(uptr a) {
 194   PROFILE_ASAN_MAPPING();
 195   return AddrIsInLowShadow(a) || AddrIsInMidShadow(a) || AddrIsInHighShadow(a);
 196 }
 197
 198 static inline bool AddrIsInShadowGap(uptr a) {
 199   PROFILE_ASAN_MAPPING();
 200   if (kMidMemBeg) {
 201     if (a <= kShadowGapEnd)
 202       return SHADOW_OFFSET == 0 || a >= kShadowGapBeg;
 203     return (a >= kShadowGap2Beg && a <= kShadowGap2End) ||
 204            (a >= kShadowGap3Beg && a <= kShadowGap3End);
 205   }
 206   // In zero-based shadow mode we treat addresses near zero as addresses
 207   // in shadow gap as well.
 208   if (SHADOW_OFFSET == 0)
 209     return a <= kShadowGapEnd;
 210   return a >= kShadowGapBeg && a <= kShadowGapEnd;
 211 }
 212
 213 static inline bool AddrIsAlignedByGranularity(uptr a) {
 214   PROFILE_ASAN_MAPPING();
 215   return (a & (SHADOW_GRANULARITY - 1)) == 0;
 216 }
 217
 218 static inline bool AddressIsPoisoned(uptr a) {
 219   PROFILE_ASAN_MAPPING();
 220   const uptr kAccessSize = 1;
 221   u8 *shadow_address = (u8*)MEM_TO_SHADOW(a);
 222   s8 shadow_value = *shadow_address;
 223   if (shadow_value) {
 224     u8 last_accessed_byte = (a & (SHADOW_GRANULARITY - 1))
 225                                  + kAccessSize - 1;
 226     return (last_accessed_byte >= shadow_value);
 227   }
 228   return false;
 229 }
 230
 231 // Must be after all calls to PROFILE_ASAN_MAPPING().
 232 static const uptr kAsanMappingProfileSize = __LINE__;
 233
 234 }  // namespace __asan
 235
 236 #endif  // ASAN_MAPPING_H