asan_mapping.h revision e89f1846d58550f919a0ef9081b11d4b0405019d 
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// With the zero shadow base we can not actually map pages starting from 0.
72// This constant is somewhat arbitrary.
73#define kZeroBaseShadowStart (1 << 18)
74
75#define kShadowGapBeg   (kLowShadowEnd ? kLowShadowEnd + 1 \
76                                       : kZeroBaseShadowStart)
77#define kShadowGapEnd   (kHighShadowBeg - 1)
78
79#define kGlobalAndStackRedzone \
80      (SHADOW_GRANULARITY < 32 ? 32 : SHADOW_GRANULARITY)
81
82namespace __asan {
83
84static inline bool AddrIsInLowMem(uptr a) {
85  return a < kLowMemEnd;
86}
87
88static inline bool AddrIsInLowShadow(uptr a) {
89  return a >= kLowShadowBeg && a <= kLowShadowEnd;
90}
91
92static inline bool AddrIsInHighMem(uptr a) {
93  return a >= kHighMemBeg && a <= kHighMemEnd;
94}
95
96static inline bool AddrIsInMem(uptr a) {
97  return AddrIsInLowMem(a) || AddrIsInHighMem(a);
98}
99
100static inline uptr MemToShadow(uptr p) {
101  CHECK(AddrIsInMem(p));
102  return MEM_TO_SHADOW(p);
103}
104
105static inline bool AddrIsInHighShadow(uptr a) {
106  return a >= kHighShadowBeg && a <=  kHighMemEnd;
107}
108
109static inline bool AddrIsInShadow(uptr a) {
110  return AddrIsInLowShadow(a) || AddrIsInHighShadow(a);
111}
112
113static inline bool AddrIsInShadowGap(uptr a) {
114  return a >= kShadowGapBeg && a <= kShadowGapEnd;
115}
116
117static inline bool AddrIsAlignedByGranularity(uptr a) {
118  return (a & (SHADOW_GRANULARITY - 1)) == 0;
119}
120
121static inline bool AddressIsPoisoned(uptr a) {
122  const uptr kAccessSize = 1;
123  u8 *shadow_address = (u8*)MemToShadow(a);
124  s8 shadow_value = *shadow_address;
125  if (shadow_value) {
126    u8 last_accessed_byte = (a & (SHADOW_GRANULARITY - 1))
127                                 + kAccessSize - 1;
128    return (last_accessed_byte >= shadow_value);
129  }
130  return false;
131}
132
133}  // namespace __asan
134
135#endif  // ASAN_MAPPING_H
136