asan_mapping.h revision 02a063660153ab4d0430b211f4dd0b3606bcbff7 
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"))) uintptr_t __asan_mapping_scale;
24extern __attribute__((visibility("default"))) uintptr_t __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
44#if __WORDSIZE == 64
45  static const size_t kHighMemEnd = 0x00007fffffffffffUL;
46#else  // __WORDSIZE == 32
47  static const size_t kHighMemEnd = 0xffffffff;
48#endif  // __WORDSIZE
49
50
51#define kLowMemBeg      0
52#define kLowMemEnd      (SHADOW_OFFSET ? SHADOW_OFFSET - 1 : 0)
53
54#define kLowShadowBeg   SHADOW_OFFSET
55#define kLowShadowEnd   MEM_TO_SHADOW(kLowMemEnd)
56
57#define kHighMemBeg     (MEM_TO_SHADOW(kHighMemEnd) + 1)
58
59#define kHighShadowBeg  MEM_TO_SHADOW(kHighMemBeg)
60#define kHighShadowEnd  MEM_TO_SHADOW(kHighMemEnd)
61
62#define kShadowGapBeg   (kLowShadowEnd ? kLowShadowEnd + 1 : 16 * kPageSize)
63#define kShadowGapEnd   (kHighShadowBeg - 1)
64
65#define kGlobalAndStackRedzone \
66      (SHADOW_GRANULARITY < 32 ? 32 : SHADOW_GRANULARITY)
67
68namespace __asan {
69
70static inline bool AddrIsInLowMem(uintptr_t a) {
71  return a < kLowMemEnd;
72}
73
74static inline bool AddrIsInLowShadow(uintptr_t a) {
75  return a >= kLowShadowBeg && a <= kLowShadowEnd;
76}
77
78static inline bool AddrIsInHighMem(uintptr_t a) {
79  return a >= kHighMemBeg && a <= kHighMemEnd;
80}
81
82static inline bool AddrIsInMem(uintptr_t a) {
83  return AddrIsInLowMem(a) || AddrIsInHighMem(a);
84}
85
86static inline uintptr_t MemToShadow(uintptr_t p) {
87  CHECK(AddrIsInMem(p));
88  return MEM_TO_SHADOW(p);
89}
90
91static inline bool AddrIsInHighShadow(uintptr_t a) {
92  return a >= kHighShadowBeg && a <=  kHighMemEnd;
93}
94
95static inline bool AddrIsInShadow(uintptr_t a) {
96  return AddrIsInLowShadow(a) || AddrIsInHighShadow(a);
97}
98
99static inline bool AddrIsAlignedByGranularity(uintptr_t a) {
100  return (a & (SHADOW_GRANULARITY - 1)) == 0;
101}
102
103static inline bool AddressIsPoisoned(uintptr_t a) {
104  const size_t kAccessSize = 1;
105  uint8_t *shadow_address = (uint8_t*)MemToShadow(a);
106  int8_t shadow_value = *shadow_address;
107  if (shadow_value) {
108    uint8_t last_accessed_byte = (a & (SHADOW_GRANULARITY - 1))
109                                 + kAccessSize - 1;
110    return (last_accessed_byte >= shadow_value);
111  }
112  return false;
113}
114
115}  // namespace __asan
116
117#endif  // ASAN_MAPPING_H
118