asan_mapping.h revision 5af39e50366f1aacbebc284f572f08ad1ad07357 
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
23extern __attribute__((visibility("default"))) uptr __asan_mapping_scale;
24extern __attribute__((visibility("default"))) 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#if SANITIZER_WORDSIZE == 64
50# if defined(__powerpc64__)
51  static const uptr kHighMemEnd = 0x00000fffffffffffUL;
52# else
53  static const uptr kHighMemEnd = 0x00007fffffffffffUL;
54# endif
55#else  // SANITIZER_WORDSIZE == 32
56  static const uptr kHighMemEnd = 0xffffffff;
57#endif  // SANITIZER_WORDSIZE
58
59
60#define kLowMemBeg      0
61#define kLowMemEnd      (SHADOW_OFFSET ? SHADOW_OFFSET - 1 : 0)
62
63#define kLowShadowBeg   SHADOW_OFFSET
64#define kLowShadowEnd   MEM_TO_SHADOW(kLowMemEnd)
65
66#define kHighMemBeg     (MEM_TO_SHADOW(kHighMemEnd) + 1)
67
68#define kHighShadowBeg  MEM_TO_SHADOW(kHighMemBeg)
69#define kHighShadowEnd  MEM_TO_SHADOW(kHighMemEnd)
70
71#define kShadowGapBeg   (kLowShadowEnd ? kLowShadowEnd + 1 : 16 * kPageSize)
72#define kShadowGapEnd   (kHighShadowBeg - 1)
73
74#define kGlobalAndStackRedzone \
75      (SHADOW_GRANULARITY < 32 ? 32 : SHADOW_GRANULARITY)
76
77namespace __asan {
78
79static inline bool AddrIsInLowMem(uptr a) {
80  return a < kLowMemEnd;
81}
82
83static inline bool AddrIsInLowShadow(uptr a) {
84  return a >= kLowShadowBeg && a <= kLowShadowEnd;
85}
86
87static inline bool AddrIsInHighMem(uptr a) {
88  return a >= kHighMemBeg && a <= kHighMemEnd;
89}
90
91static inline bool AddrIsInMem(uptr a) {
92  return AddrIsInLowMem(a) || AddrIsInHighMem(a);
93}
94
95static inline uptr MemToShadow(uptr p) {
96  CHECK(AddrIsInMem(p));
97  return MEM_TO_SHADOW(p);
98}
99
100static inline bool AddrIsInHighShadow(uptr a) {
101  return a >= kHighShadowBeg && a <=  kHighMemEnd;
102}
103
104static inline bool AddrIsInShadow(uptr a) {
105  return AddrIsInLowShadow(a) || AddrIsInHighShadow(a);
106}
107
108static inline bool AddrIsInShadowGap(uptr a) {
109  return a >= kShadowGapBeg && a <= kShadowGapEnd;
110}
111
112static inline bool AddrIsAlignedByGranularity(uptr a) {
113  return (a & (SHADOW_GRANULARITY - 1)) == 0;
114}
115
116static inline bool AddressIsPoisoned(uptr a) {
117  const uptr kAccessSize = 1;
118  u8 *shadow_address = (u8*)MemToShadow(a);
119  s8 shadow_value = *shadow_address;
120  if (shadow_value) {
121    u8 last_accessed_byte = (a & (SHADOW_GRANULARITY - 1))
122                                 + kAccessSize - 1;
123    return (last_accessed_byte >= shadow_value);
124  }
125  return false;
126}
127
128}  // namespace __asan
129
130#endif  // ASAN_MAPPING_H
131