libasan/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 #if ASAN_FLEXIBLE_MAPPING_AND_OFFSET == 1
  21 extern __attribute__((visibility("default"))) uptr __asan_mapping_scale;
  22 extern __attribute__((visibility("default"))) uptr __asan_mapping_offset;
  23 # define SHADOW_SCALE (__asan_mapping_scale)
  24 # define SHADOW_OFFSET (__asan_mapping_offset)
  25 #else
  26 # if ASAN_ANDROID
  27 #  define SHADOW_SCALE (3)
  28 #  define SHADOW_OFFSET (0)
  29 # else
  30 #  define SHADOW_SCALE (3)
  31 #  if __WORDSIZE == 32
  32 #   define SHADOW_OFFSET (1 << 29)
  33 #  else
  34 #   define SHADOW_OFFSET (1ULL << 44)
  35 #  endif
  36 # endif
  37 #endif  // ASAN_FLEXIBLE_MAPPING_AND_OFFSET
  38
  39 #define SHADOW_GRANULARITY (1ULL << SHADOW_SCALE)
  40 #define MEM_TO_SHADOW(mem) (((mem) >> SHADOW_SCALE) | (SHADOW_OFFSET))
  41 #define SHADOW_TO_MEM(shadow) (((shadow) - SHADOW_OFFSET) << SHADOW_SCALE)
  42
  43 #if __WORDSIZE == 64
  44   static const uptr kHighMemEnd = 0x00007fffffffffffUL;
  45 #else  // __WORDSIZE == 32
  46   static const uptr kHighMemEnd = 0xffffffff;
  47 #endif  // __WORDSIZE
  48
  49
  50 #define kLowMemBeg      0
  51 #define kLowMemEnd      (SHADOW_OFFSET ? SHADOW_OFFSET - 1 : 0)
  52
  53 #define kLowShadowBeg   SHADOW_OFFSET
  54 #define kLowShadowEnd   MEM_TO_SHADOW(kLowMemEnd)
  55
  56 #define kHighMemBeg     (MEM_TO_SHADOW(kHighMemEnd) + 1)
  57
  58 #define kHighShadowBeg  MEM_TO_SHADOW(kHighMemBeg)
  59 #define kHighShadowEnd  MEM_TO_SHADOW(kHighMemEnd)
  60
  61 #define kShadowGapBeg   (kLowShadowEnd ? kLowShadowEnd + 1 : 16 * kPageSize)
  62 #define kShadowGapEnd   (kHighShadowBeg - 1)
  63
  64 #define kGlobalAndStackRedzone \
  65       (SHADOW_GRANULARITY < 32 ? 32 : SHADOW_GRANULARITY)
  66
  67 namespace __asan {
  68
  69 static inline bool AddrIsInLowMem(uptr a) {
  70   return a < kLowMemEnd;
  71 }
  72
  73 static inline bool AddrIsInLowShadow(uptr a) {
  74   return a >= kLowShadowBeg && a <= kLowShadowEnd;
  75 }
  76
  77 static inline bool AddrIsInHighMem(uptr a) {
  78   return a >= kHighMemBeg && a <= kHighMemEnd;
  79 }
  80
  81 static inline bool AddrIsInMem(uptr a) {
  82   return AddrIsInLowMem(a) || AddrIsInHighMem(a);
  83 }
  84
  85 static inline uptr MemToShadow(uptr p) {
  86   CHECK(AddrIsInMem(p));
  87   return MEM_TO_SHADOW(p);
  88 }
  89
  90 static inline bool AddrIsInHighShadow(uptr a) {
  91   return a >= kHighShadowBeg && a <=  kHighMemEnd;
  92 }
  93
  94 static inline bool AddrIsInShadow(uptr a) {
  95   return AddrIsInLowShadow(a) || AddrIsInHighShadow(a);
  96 }
  97
  98 static inline bool AddrIsInShadowGap(uptr a) {
  99   return a >= kShadowGapBeg && a <= kShadowGapEnd;
 100 }
 101
 102 static inline bool AddrIsAlignedByGranularity(uptr a) {
 103   return (a & (SHADOW_GRANULARITY - 1)) == 0;
 104 }
 105
 106 static inline bool AddressIsPoisoned(uptr a) {
 107   const uptr kAccessSize = 1;
 108   u8 *shadow_address = (u8*)MemToShadow(a);
 109   s8 shadow_value = *shadow_address;
 110   if (shadow_value) {
 111     u8 last_accessed_byte = (a & (SHADOW_GRANULARITY - 1))
 112                                  + kAccessSize - 1;
 113     return (last_accessed_byte >= shadow_value);
 114   }
 115   return false;
 116 }
 117
 118 }  // namespace __asan
 119
 120 #endif  // ASAN_MAPPING_H