asan_mapping.h revision ed847e39a3f993e52fd0a290d08cadf723951ea3 
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 SANITIZER_INTERFACE_ATTRIBUTE uptr __asan_mapping_scale;
24extern 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
68namespace __asan {
69
70SANITIZER_INTERFACE_ATTRIBUTE
71extern uptr kHighMemEnd;  // Initialized in __asan_init.
72
73static inline bool AddrIsInLowMem(uptr a) {
74  return a < kLowMemEnd;
75}
76
77static inline bool AddrIsInLowShadow(uptr a) {
78  return a >= kLowShadowBeg && a <= kLowShadowEnd;
79}
80
81static inline bool AddrIsInHighMem(uptr a) {
82  return a >= kHighMemBeg && a <= kHighMemEnd;
83}
84
85static inline bool AddrIsInMem(uptr a) {
86  return AddrIsInLowMem(a) || AddrIsInHighMem(a);
87}
88
89static inline uptr MemToShadow(uptr p) {
90  CHECK(AddrIsInMem(p));
91  return MEM_TO_SHADOW(p);
92}
93
94static inline bool AddrIsInHighShadow(uptr a) {
95  return a >= kHighShadowBeg && a <=  kHighMemEnd;
96}
97
98static inline bool AddrIsInShadow(uptr a) {
99  return AddrIsInLowShadow(a) || AddrIsInHighShadow(a);
100}
101
102static 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
110static inline bool AddrIsAlignedByGranularity(uptr a) {
111  return (a & (SHADOW_GRANULARITY - 1)) == 0;
112}
113
114static 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
129