asan_mapping.h revision 606d3bc68a071c35acd0490678ce9ebc4c7e6332 
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#    if ASAN_MAC
40#     define SHADOW_OFFSET (1ULL << 44)
41#    else
42#     define SHADOW_OFFSET 0x7fff8000ULL
43#    endif
44#   endif
45#  endif
46# endif
47#endif  // ASAN_FLEXIBLE_MAPPING_AND_OFFSET
48
49#define SHADOW_GRANULARITY (1ULL << SHADOW_SCALE)
50#define MEM_TO_SHADOW(mem) (((mem) >> SHADOW_SCALE) + (SHADOW_OFFSET))
51#define SHADOW_TO_MEM(shadow) (((shadow) - SHADOW_OFFSET) << SHADOW_SCALE)
52
53#define kLowMemBeg      0
54#define kLowMemEnd      (SHADOW_OFFSET ? SHADOW_OFFSET - 1 : 0)
55
56#define kLowShadowBeg   SHADOW_OFFSET
57#define kLowShadowEnd   MEM_TO_SHADOW(kLowMemEnd)
58
59#define kHighMemBeg     (MEM_TO_SHADOW(kHighMemEnd) + 1)
60
61#define kHighShadowBeg  MEM_TO_SHADOW(kHighMemBeg)
62#define kHighShadowEnd  MEM_TO_SHADOW(kHighMemEnd)
63
64// With the zero shadow base we can not actually map pages starting from 0.
65// This constant is somewhat arbitrary.
66#define kZeroBaseShadowStart (1 << 18)
67
68#define kShadowGapBeg   (kLowShadowEnd ? kLowShadowEnd + 1 \
69                                       : kZeroBaseShadowStart)
70#define kShadowGapEnd   (kHighShadowBeg - 1)
71
72namespace __asan {
73
74SANITIZER_INTERFACE_ATTRIBUTE
75extern uptr kHighMemEnd;  // Initialized in __asan_init.
76
77static inline bool AddrIsInLowMem(uptr a) {
78  return a < kLowMemEnd;
79}
80
81static inline bool AddrIsInLowShadow(uptr a) {
82  return a >= kLowShadowBeg && a <= kLowShadowEnd;
83}
84
85static inline bool AddrIsInHighMem(uptr a) {
86  return a >= kHighMemBeg && a <= kHighMemEnd;
87}
88
89static inline bool AddrIsInMem(uptr a) {
90  return AddrIsInLowMem(a) || AddrIsInHighMem(a);
91}
92
93static inline uptr MemToShadow(uptr p) {
94  CHECK(AddrIsInMem(p));
95  return MEM_TO_SHADOW(p);
96}
97
98static inline bool AddrIsInHighShadow(uptr a) {
99  return a >= kHighShadowBeg && a <=  kHighMemEnd;
100}
101
102static inline bool AddrIsInShadow(uptr a) {
103  return AddrIsInLowShadow(a) || AddrIsInHighShadow(a);
104}
105
106static inline bool AddrIsInShadowGap(uptr a) {
107  // In zero-based shadow mode we treat addresses near zero as addresses
108  // in shadow gap as well.
109  if (SHADOW_OFFSET == 0)
110    return a <= kShadowGapEnd;
111  return a >= kShadowGapBeg && a <= kShadowGapEnd;
112}
113
114static inline bool AddrIsAlignedByGranularity(uptr a) {
115  return (a & (SHADOW_GRANULARITY - 1)) == 0;
116}
117
118static inline bool AddressIsPoisoned(uptr a) {
119  const uptr kAccessSize = 1;
120  u8 *shadow_address = (u8*)MemToShadow(a);
121  s8 shadow_value = *shadow_address;
122  if (shadow_value) {
123    u8 last_accessed_byte = (a & (SHADOW_GRANULARITY - 1))
124                                 + kAccessSize - 1;
125    return (last_accessed_byte >= shadow_value);
126  }
127  return false;
128}
129
130}  // namespace __asan
131
132#endif  // ASAN_MAPPING_H
133