asan_mapping.h revision 79d12e87fbcc1b2342d76367b99b83adf9cbf499 
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# ifdef ANDROID
29#  define SHADOW_SCALE (3)
30#  define SHADOW_OFFSET (0)
31# else
32#  define SHADOW_SCALE (3)
33#  if __WORDSIZE == 32
34#   define SHADOW_OFFSET (1 << 29)
35#  else
36#   define SHADOW_OFFSET (1ULL << 44)
37#  endif
38# endif
39#endif  // ASAN_FLEXIBLE_MAPPING_AND_OFFSET
40
41#define SHADOW_GRANULARITY (1ULL << SHADOW_SCALE)
42#define MEM_TO_SHADOW(mem) (((mem) >> SHADOW_SCALE) | (SHADOW_OFFSET))
43#define SHADOW_TO_MEM(shadow) (((shadow) - SHADOW_OFFSET) << SHADOW_SCALE)
44
45#if __WORDSIZE == 64
46  static const uptr kHighMemEnd = 0x00007fffffffffffUL;
47#else  // __WORDSIZE == 32
48  static const uptr kHighMemEnd = 0xffffffff;
49#endif  // __WORDSIZE
50
51
52#define kLowMemBeg      0
53#define kLowMemEnd      (SHADOW_OFFSET ? SHADOW_OFFSET - 1 : 0)
54
55#define kLowShadowBeg   SHADOW_OFFSET
56#define kLowShadowEnd   MEM_TO_SHADOW(kLowMemEnd)
57
58#define kHighMemBeg     (MEM_TO_SHADOW(kHighMemEnd) + 1)
59
60#define kHighShadowBeg  MEM_TO_SHADOW(kHighMemBeg)
61#define kHighShadowEnd  MEM_TO_SHADOW(kHighMemEnd)
62
63#define kShadowGapBeg   (kLowShadowEnd ? kLowShadowEnd + 1 : 16 * kPageSize)
64#define kShadowGapEnd   (kHighShadowBeg - 1)
65
66#define kGlobalAndStackRedzone \
67      (SHADOW_GRANULARITY < 32 ? 32 : SHADOW_GRANULARITY)
68
69namespace __asan {
70
71static inline bool AddrIsInLowMem(uptr a) {
72  return a < kLowMemEnd;
73}
74
75static inline bool AddrIsInLowShadow(uptr a) {
76  return a >= kLowShadowBeg && a <= kLowShadowEnd;
77}
78
79static inline bool AddrIsInHighMem(uptr a) {
80  return a >= kHighMemBeg && a <= kHighMemEnd;
81}
82
83static inline bool AddrIsInMem(uptr a) {
84  return AddrIsInLowMem(a) || AddrIsInHighMem(a);
85}
86
87static inline uptr MemToShadow(uptr p) {
88  CHECK(AddrIsInMem(p));
89  return MEM_TO_SHADOW(p);
90}
91
92static inline bool AddrIsInHighShadow(uptr a) {
93  return a >= kHighShadowBeg && a <=  kHighMemEnd;
94}
95
96static inline bool AddrIsInShadow(uptr a) {
97  return AddrIsInLowShadow(a) || AddrIsInHighShadow(a);
98}
99
100static inline bool AddrIsInShadowGap(uptr a) {
101  return a >= kShadowGapBeg && a <= kShadowGapEnd;
102}
103
104static inline bool AddrIsAlignedByGranularity(uptr a) {
105  return (a & (SHADOW_GRANULARITY - 1)) == 0;
106}
107
108static inline bool AddressIsPoisoned(uptr a) {
109  const uptr kAccessSize = 1;
110  u8 *shadow_address = (u8*)MemToShadow(a);
111  s8 shadow_value = *shadow_address;
112  if (shadow_value) {
113    u8 last_accessed_byte = (a & (SHADOW_GRANULARITY - 1))
114                                 + kAccessSize - 1;
115    return (last_accessed_byte >= shadow_value);
116  }
117  return false;
118}
119
120}  // namespace __asan
121
122#endif  // ASAN_MAPPING_H
123