lib/asan/asan_mapping.h

   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 on x86_64 machine:
  47 // || `[0x40000000, 0xffffffff]` || HighMem    ||
  48 // || `[0x28000000, 0x3fffffff]` || HighShadow ||
  49 // || `[0x24000000, 0x27ffffff]` || ShadowGap  ||
  50 // || `[0x20000000, 0x23ffffff]` || LowShadow  ||
  51 // || `[0x00000000, 0x1fffffff]` || LowMem     ||
  52 //
  53 // Default Linux/i386 mapping on i386 machine
  54 // (addresses starting with 0xc0000000 are reserved
  55 // for kernel and thus not sanitized):
  56 // || `[0x38000000, 0xbfffffff]` || HighMem    ||
  57 // || `[0x27000000, 0x37ffffff]` || HighShadow ||
  58 // || `[0x24000000, 0x26ffffff]` || ShadowGap  ||
  59 // || `[0x20000000, 0x23ffffff]` || LowShadow  ||
  60 // || `[0x00000000, 0x1fffffff]` || LowMem     ||
  61 //
  62 // Default Linux/MIPS mapping:
  63 // || `[0x2aaa8000, 0xffffffff]` || HighMem    ||
  64 // || `[0x0fffd000, 0x2aaa7fff]` || HighShadow ||
  65 // || `[0x0bffd000, 0x0fffcfff]` || ShadowGap  ||
  66 // || `[0x0aaa8000, 0x0bffcfff]` || LowShadow  ||
  67 // || `[0x00000000, 0x0aaa7fff]` || LowMem     ||
  68
  69 static const u64 kDefaultShadowScale = 3;
  70 static const u64 kDefaultShadowOffset32 = 1ULL << 29;  // 0x20000000
  71 static const u64 kIosShadowOffset32 = 1ULL << 30;  // 0x40000000
  72 static const u64 kDefaultShadowOffset64 = 1ULL << 44;
  73 static const u64 kDefaultShort64bitShadowOffset = 0x7FFF8000;  // < 2G.
  74 static const u64 kAArch64_ShadowOffset64 = 1ULL << 36;
  75 static const u64 kMIPS32_ShadowOffset32 = 0x0aaa8000;
  76
  77 #define SHADOW_SCALE kDefaultShadowScale
  78 #if SANITIZER_ANDROID
  79 # define SHADOW_OFFSET (0)
  80 #else
  81 # if SANITIZER_WORDSIZE == 32
  82 #  if defined(__mips__)
  83 #    define SHADOW_OFFSET kMIPS32_ShadowOffset32
  84 #  else
  85 #    if SANITIZER_IOS
  86 #      define SHADOW_OFFSET kIosShadowOffset32
  87 #    else
  88 #      define SHADOW_OFFSET kDefaultShadowOffset32
  89 #    endif
  90 #  endif
  91 # else
  92 #  if defined(__aarch64__)
  93 #    define SHADOW_OFFSET kAArch64_ShadowOffset64
  94 #  elif SANITIZER_MAC
  95 #   define SHADOW_OFFSET kDefaultShadowOffset64
  96 #  else
  97 #   define SHADOW_OFFSET kDefaultShort64bitShadowOffset
  98 #  endif
  99 # endif
 100 #endif
 101
 102 #define SHADOW_GRANULARITY (1ULL << SHADOW_SCALE)
 103 #define MEM_TO_SHADOW(mem) (((mem) >> SHADOW_SCALE) + (SHADOW_OFFSET))
 104 #define SHADOW_TO_MEM(shadow) (((shadow) - SHADOW_OFFSET) << SHADOW_SCALE)
 105
 106 #define kLowMemBeg      0
 107 #define kLowMemEnd      (SHADOW_OFFSET ? SHADOW_OFFSET - 1 : 0)
 108
 109 #define kLowShadowBeg   SHADOW_OFFSET
 110 #define kLowShadowEnd   MEM_TO_SHADOW(kLowMemEnd)
 111
 112 #define kHighMemBeg     (MEM_TO_SHADOW(kHighMemEnd) + 1)
 113
 114 #define kHighShadowBeg  MEM_TO_SHADOW(kHighMemBeg)
 115 #define kHighShadowEnd  MEM_TO_SHADOW(kHighMemEnd)
 116
 117 # define kMidShadowBeg MEM_TO_SHADOW(kMidMemBeg)
 118 # define kMidShadowEnd MEM_TO_SHADOW(kMidMemEnd)
 119
 120 // With the zero shadow base we can not actually map pages starting from 0.
 121 // This constant is somewhat arbitrary.
 122 #define kZeroBaseShadowStart (1 << 18)
 123
 124 #define kShadowGapBeg   (kLowShadowEnd ? kLowShadowEnd + 1 \
 125                                        : kZeroBaseShadowStart)
 126 #define kShadowGapEnd   ((kMidMemBeg ? kMidShadowBeg : kHighShadowBeg) - 1)
 127
 128 #define kShadowGap2Beg (kMidMemBeg ? kMidShadowEnd + 1 : 0)
 129 #define kShadowGap2End (kMidMemBeg ? kMidMemBeg - 1 : 0)
 130
 131 #define kShadowGap3Beg (kMidMemBeg ? kMidMemEnd + 1 : 0)
 132 #define kShadowGap3End (kMidMemBeg ? kHighShadowBeg - 1 : 0)
 133
 134 #define DO_ASAN_MAPPING_PROFILE 0  // Set to 1 to profile the functions below.
 135
 136 #if DO_ASAN_MAPPING_PROFILE
 137 # define PROFILE_ASAN_MAPPING() AsanMappingProfile[__LINE__]++;
 138 #else
 139 # define PROFILE_ASAN_MAPPING()
 140 #endif
 141
 142 // If 1, all shadow boundaries are constants.
 143 // Don't set to 1 other than for testing.
 144 #define ASAN_FIXED_MAPPING 0
 145
 146 namespace __asan {
 147
 148 extern uptr AsanMappingProfile[];
 149
 150 #if ASAN_FIXED_MAPPING
 151 // Fixed mapping for 64-bit Linux. Mostly used for performance comparison
 152 // with non-fixed mapping. As of r175253 (Feb 2013) the performance
 153 // difference between fixed and non-fixed mapping is below the noise level.
 154 static uptr kHighMemEnd = 0x7fffffffffffULL;
 155 static uptr kMidMemBeg =    0x3000000000ULL;
 156 static uptr kMidMemEnd =    0x4fffffffffULL;
 157 #else
 158 extern uptr kHighMemEnd, kMidMemBeg, kMidMemEnd;  // Initialized in __asan_init.
 159 #endif
 160
 161 static inline bool AddrIsInLowMem(uptr a) {
 162   PROFILE_ASAN_MAPPING();
 163   return a < kLowMemEnd;
 164 }
 165
 166 static inline bool AddrIsInLowShadow(uptr a) {
 167   PROFILE_ASAN_MAPPING();
 168   return a >= kLowShadowBeg && a <= kLowShadowEnd;
 169 }
 170
 171 static inline bool AddrIsInHighMem(uptr a) {
 172   PROFILE_ASAN_MAPPING();
 173   return a >= kHighMemBeg && a <= kHighMemEnd;
 174 }
 175
 176 static inline bool AddrIsInMidMem(uptr a) {
 177   PROFILE_ASAN_MAPPING();
 178   return kMidMemBeg && a >= kMidMemBeg && a <= kMidMemEnd;
 179 }
 180
 181 static inline bool AddrIsInMem(uptr a) {
 182   PROFILE_ASAN_MAPPING();
 183   return AddrIsInLowMem(a) || AddrIsInMidMem(a) || AddrIsInHighMem(a);
 184 }
 185
 186 static inline uptr MemToShadow(uptr p) {
 187   PROFILE_ASAN_MAPPING();
 188   CHECK(AddrIsInMem(p));
 189   return MEM_TO_SHADOW(p);
 190 }
 191
 192 static inline bool AddrIsInHighShadow(uptr a) {
 193   PROFILE_ASAN_MAPPING();
 194   return a >= kHighShadowBeg && a <= kHighMemEnd;
 195 }
 196
 197 static inline bool AddrIsInMidShadow(uptr a) {
 198   PROFILE_ASAN_MAPPING();
 199   return kMidMemBeg && a >= kMidShadowBeg && a <= kMidMemEnd;
 200 }
 201
 202 static inline bool AddrIsInShadow(uptr a) {
 203   PROFILE_ASAN_MAPPING();
 204   return AddrIsInLowShadow(a) || AddrIsInMidShadow(a) || AddrIsInHighShadow(a);
 205 }
 206
 207 static inline bool AddrIsInShadowGap(uptr a) {
 208   PROFILE_ASAN_MAPPING();
 209   if (kMidMemBeg) {
 210     if (a <= kShadowGapEnd)
 211       return SHADOW_OFFSET == 0 || a >= kShadowGapBeg;
 212     return (a >= kShadowGap2Beg && a <= kShadowGap2End) ||
 213            (a >= kShadowGap3Beg && a <= kShadowGap3End);
 214   }
 215   // In zero-based shadow mode we treat addresses near zero as addresses
 216   // in shadow gap as well.
 217   if (SHADOW_OFFSET == 0)
 218     return a <= kShadowGapEnd;
 219   return a >= kShadowGapBeg && a <= kShadowGapEnd;
 220 }
 221
 222 static inline bool AddrIsAlignedByGranularity(uptr a) {
 223   PROFILE_ASAN_MAPPING();
 224   return (a & (SHADOW_GRANULARITY - 1)) == 0;
 225 }
 226
 227 static inline bool AddressIsPoisoned(uptr a) {
 228   PROFILE_ASAN_MAPPING();
 229   const uptr kAccessSize = 1;
 230   u8 *shadow_address = (u8*)MEM_TO_SHADOW(a);
 231   s8 shadow_value = *shadow_address;
 232   if (shadow_value) {
 233     u8 last_accessed_byte = (a & (SHADOW_GRANULARITY - 1))
 234                                  + kAccessSize - 1;
 235     return (last_accessed_byte >= shadow_value);
 236   }
 237   return false;
 238 }
 239
 240 // Must be after all calls to PROFILE_ASAN_MAPPING().
 241 static const uptr kAsanMappingProfileSize = __LINE__;
 242
 243 }  // namespace __asan
 244
 245 #endif  // ASAN_MAPPING_H