libsanitizer/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 #if ASAN_FLEXIBLE_MAPPING_AND_OFFSET == 1
  23 extern SANITIZER_INTERFACE_ATTRIBUTE uptr __asan_mapping_scale;
  24 extern SANITIZER_INTERFACE_ATTRIBUTE uptr __asan_mapping_offset;
  25 # define SHADOW_SCALE (__asan_mapping_scale)
  26 # define SHADOW_OFFSET (__asan_mapping_offset)
  27 #else
  28 # if ASAN_ANDROID
  29 #  define SHADOW_SCALE (3)
  30 #  define SHADOW_OFFSET (0)
  31 # else
  32 #  define SHADOW_SCALE (3)
  33 #  if SANITIZER_WORDSIZE == 32
  34 #   define SHADOW_OFFSET (1 << 29)
  35 #  else
  36 #   if defined(__powerpc64__)
  37 #    define SHADOW_OFFSET (1ULL << 41)
  38 #   else
  39 #    define SHADOW_OFFSET (1ULL << 44)
  40 #   endif
  41 #  endif
  42 # endif
  43 #endif  // ASAN_FLEXIBLE_MAPPING_AND_OFFSET
  44
  45 #define SHADOW_GRANULARITY (1ULL << SHADOW_SCALE)
  46 #define MEM_TO_SHADOW(mem) (((mem) >> SHADOW_SCALE) + (SHADOW_OFFSET))
  47 #define SHADOW_TO_MEM(shadow) (((shadow) - SHADOW_OFFSET) << SHADOW_SCALE)
  48
  49 #define kLowMemBeg      0
  50 #define kLowMemEnd      (SHADOW_OFFSET ? SHADOW_OFFSET - 1 : 0)
  51
  52 #define kLowShadowBeg   SHADOW_OFFSET
  53 #define kLowShadowEnd   MEM_TO_SHADOW(kLowMemEnd)
  54
  55 #define kHighMemBeg     (MEM_TO_SHADOW(kHighMemEnd) + 1)
  56
  57 #define kHighShadowBeg  MEM_TO_SHADOW(kHighMemBeg)
  58 #define kHighShadowEnd  MEM_TO_SHADOW(kHighMemEnd)
  59
  60 // With the zero shadow base we can not actually map pages starting from 0.
  61 // This constant is somewhat arbitrary.
  62 #define kZeroBaseShadowStart (1 << 18)
  63
  64 #define kShadowGapBeg   (kLowShadowEnd ? kLowShadowEnd + 1 \
  65                                        : kZeroBaseShadowStart)
  66 #define kShadowGapEnd   (kHighShadowBeg - 1)
  67
  68 namespace __asan {
  69
  70 SANITIZER_INTERFACE_ATTRIBUTE
  71 extern uptr kHighMemEnd;  // Initialized in __asan_init.
  72
  73 static inline bool AddrIsInLowMem(uptr a) {
  74   return a < kLowMemEnd;
  75 }
  76
  77 static inline bool AddrIsInLowShadow(uptr a) {
  78   return a >= kLowShadowBeg && a <= kLowShadowEnd;
  79 }
  80
  81 static inline bool AddrIsInHighMem(uptr a) {
  82   return a >= kHighMemBeg && a <= kHighMemEnd;
  83 }
  84
  85 static inline bool AddrIsInMem(uptr a) {
  86   return AddrIsInLowMem(a) || AddrIsInHighMem(a);
  87 }
  88
  89 static inline uptr MemToShadow(uptr p) {
  90   CHECK(AddrIsInMem(p));
  91   return MEM_TO_SHADOW(p);
  92 }
  93
  94 static inline bool AddrIsInHighShadow(uptr a) {
  95   return a >= kHighShadowBeg && a <=  kHighMemEnd;
  96 }
  97
  98 static inline bool AddrIsInShadow(uptr a) {
  99   return AddrIsInLowShadow(a) || AddrIsInHighShadow(a);
 100 }
 101
 102 static inline bool AddrIsInShadowGap(uptr a) {
 103   // In zero-based shadow mode we treat addresses near zero as addresses
 104   // in shadow gap as well.
 105   if (SHADOW_OFFSET == 0)
 106     return a <= kShadowGapEnd;
 107   return a >= kShadowGapBeg && a <= kShadowGapEnd;
 108 }
 109
 110 static inline bool AddrIsAlignedByGranularity(uptr a) {
 111   return (a & (SHADOW_GRANULARITY - 1)) == 0;
 112 }
 113
 114 static inline bool AddressIsPoisoned(uptr a) {
 115   const uptr kAccessSize = 1;
 116   u8 *shadow_address = (u8*)MemToShadow(a);
 117   s8 shadow_value = *shadow_address;
 118   if (shadow_value) {
 119     u8 last_accessed_byte = (a & (SHADOW_GRANULARITY - 1))
 120                                  + kAccessSize - 1;
 121     return (last_accessed_byte >= shadow_value);
 122   }
 123   return false;
 124 }
 125
 126 }  // namespace __asan
 127
 128 #endif  // ASAN_MAPPING_H