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 #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 SANITIZER_WORDSIZE == 32
  32 #   define SHADOW_OFFSET (1 << 29)
  33 #  else
  34 #   if defined(__powerpc64__)
  35 #    define SHADOW_OFFSET (1ULL << 41)
  36 #   else
  37 #    define SHADOW_OFFSET (1ULL << 44)
  38 #   endif
  39 #  endif
  40 # endif
  41 #endif  // ASAN_FLEXIBLE_MAPPING_AND_OFFSET
  42
  43 #define SHADOW_GRANULARITY (1ULL << SHADOW_SCALE)
  44 #define MEM_TO_SHADOW(mem) (((mem) >> SHADOW_SCALE) | (SHADOW_OFFSET))
  45 #define SHADOW_TO_MEM(shadow) (((shadow) - SHADOW_OFFSET) << SHADOW_SCALE)
  46
  47 #if SANITIZER_WORDSIZE == 64
  48 # if defined(__powerpc64__)
  49   static const uptr kHighMemEnd = 0x00000fffffffffffUL;
  50 # else
  51   static const uptr kHighMemEnd = 0x00007fffffffffffUL;
  52 # endif
  53 #else  // SANITIZER_WORDSIZE == 32
  54   static const uptr kHighMemEnd = 0xffffffff;
  55 #endif  // SANITIZER_WORDSIZE
  56
  57
  58 #define kLowMemBeg      0
  59 #define kLowMemEnd      (SHADOW_OFFSET ? SHADOW_OFFSET - 1 : 0)
  60
  61 #define kLowShadowBeg   SHADOW_OFFSET
  62 #define kLowShadowEnd   MEM_TO_SHADOW(kLowMemEnd)
  63
  64 #define kHighMemBeg     (MEM_TO_SHADOW(kHighMemEnd) + 1)
  65
  66 #define kHighShadowBeg  MEM_TO_SHADOW(kHighMemBeg)
  67 #define kHighShadowEnd  MEM_TO_SHADOW(kHighMemEnd)
  68
  69 // With the zero shadow base we can not actually map pages starting from 0.
  70 // This constant is somewhat arbitrary.
  71 #define kZeroBaseShadowStart (1 << 18)
  72
  73 #define kShadowGapBeg   (kLowShadowEnd ? kLowShadowEnd + 1 \
  74                                        : kZeroBaseShadowStart)
  75 #define kShadowGapEnd   (kHighShadowBeg - 1)
  76
  77 #define kGlobalAndStackRedzone \
  78       (SHADOW_GRANULARITY < 32 ? 32 : SHADOW_GRANULARITY)
  79
  80 namespace __asan {
  81
  82 static inline bool AddrIsInLowMem(uptr a) {
  83   return a < kLowMemEnd;
  84 }
  85
  86 static inline bool AddrIsInLowShadow(uptr a) {
  87   return a >= kLowShadowBeg && a <= kLowShadowEnd;
  88 }
  89
  90 static inline bool AddrIsInHighMem(uptr a) {
  91   return a >= kHighMemBeg && a <= kHighMemEnd;
  92 }
  93
  94 static inline bool AddrIsInMem(uptr a) {
  95   return AddrIsInLowMem(a) || AddrIsInHighMem(a);
  96 }
  97
  98 static inline uptr MemToShadow(uptr p) {
  99   CHECK(AddrIsInMem(p));
 100   return MEM_TO_SHADOW(p);
 101 }
 102
 103 static inline bool AddrIsInHighShadow(uptr a) {
 104   return a >= kHighShadowBeg && a <=  kHighMemEnd;
 105 }
 106
 107 static inline bool AddrIsInShadow(uptr a) {
 108   return AddrIsInLowShadow(a) || AddrIsInHighShadow(a);
 109 }
 110
 111 static inline bool AddrIsInShadowGap(uptr a) {
 112   return a >= kShadowGapBeg && a <= kShadowGapEnd;
 113 }
 114
 115 static inline bool AddrIsAlignedByGranularity(uptr a) {
 116   return (a & (SHADOW_GRANULARITY - 1)) == 0;
 117 }
 118
 119 static inline bool AddressIsPoisoned(uptr a) {
 120   const uptr kAccessSize = 1;
 121   u8 *shadow_address = (u8*)MemToShadow(a);
 122   s8 shadow_value = *shadow_address;
 123   if (shadow_value) {
 124     u8 last_accessed_byte = (a & (SHADOW_GRANULARITY - 1))
 125                                  + kAccessSize - 1;
 126     return (last_accessed_byte >= shadow_value);
 127   }
 128   return false;
 129 }
 130
 131 }  // namespace __asan
 132
 133 #endif  // ASAN_MAPPING_H