asan_mapping.h revision 3972ea03aa52d81ca324945ba94eea22d403df12 
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#define SHADOW_SCALE (3)
29#if __WORDSIZE == 32
30#define SHADOW_OFFSET (1 << 29)
31#else
32#define SHADOW_OFFSET (1ULL << 44)
33#endif
34#endif  // ASAN_FLEXIBLE_MAPPING_AND_OFFSET
35
36#define SHADOW_GRANULARITY (1ULL << SHADOW_SCALE)
37#define MEM_TO_SHADOW(mem) (((mem) >> SHADOW_SCALE) | (SHADOW_OFFSET))
38#define SHADOW_TO_MEM(shadow) (((shadow) - SHADOW_OFFSET) << SHADOW_SCALE)
39
40#if __WORDSIZE == 64
41  static const size_t kHighMemEnd = 0x00007fffffffffffUL;
42#else  // __WORDSIZE == 32
43  static const size_t kHighMemEnd = 0xffffffff;
44#endif  // __WORDSIZE
45
46
47#define kLowMemBeg      0
48#define kLowMemEnd      (SHADOW_OFFSET ? SHADOW_OFFSET - 1 : 0)
49
50#define kLowShadowBeg   SHADOW_OFFSET
51#define kLowShadowEnd   MEM_TO_SHADOW(kLowMemEnd)
52
53#define kHighMemBeg     (MEM_TO_SHADOW(kHighMemEnd) + 1)
54
55#define kHighShadowBeg  MEM_TO_SHADOW(kHighMemBeg)
56#define kHighShadowEnd  MEM_TO_SHADOW(kHighMemEnd)
57
58#define kShadowGapBeg   (kLowShadowEnd ? kLowShadowEnd + 1 : 16 * kPageSize)
59#define kShadowGapEnd   (kHighShadowBeg - 1)
60
61#define kGlobalAndStackRedzone \
62      (SHADOW_GRANULARITY < 32 ? 32 : SHADOW_GRANULARITY)
63
64namespace __asan {
65
66static inline bool AddrIsInLowMem(uintptr_t a) {
67  return a < kLowMemEnd;
68}
69
70static inline bool AddrIsInLowShadow(uintptr_t a) {
71  return a >= kLowShadowBeg && a <= kLowShadowEnd;
72}
73
74static inline bool AddrIsInHighMem(uintptr_t a) {
75  return a >= kHighMemBeg && a <= kHighMemEnd;
76}
77
78static inline bool AddrIsInMem(uintptr_t a) {
79  return AddrIsInLowMem(a) || AddrIsInHighMem(a);
80}
81
82static inline uintptr_t MemToShadow(uintptr_t p) {
83  CHECK(AddrIsInMem(p));
84  return MEM_TO_SHADOW(p);
85}
86
87static inline bool AddrIsInHighShadow(uintptr_t a) {
88  return a >= kHighShadowBeg && a <=  kHighMemEnd;
89}
90
91static inline bool AddrIsInShadow(uintptr_t a) {
92  return AddrIsInLowShadow(a) || AddrIsInHighShadow(a);
93}
94
95static inline bool AddrIsAlignedByGranularity(uintptr_t a) {
96  return (a & (SHADOW_GRANULARITY - 1)) == 0;
97}
98
99static inline bool AddressIsPoisoned(uintptr_t a) {
100  const size_t kAccessSize = 1;
101  uint8_t *shadow_address = (uint8_t*)MemToShadow(a);
102  int8_t shadow_value = *shadow_address;
103  if (shadow_value) {
104    uint8_t last_accessed_byte = (a & (SHADOW_GRANULARITY - 1))
105                                 + kAccessSize - 1;
106    return (last_accessed_byte >= shadow_value);
107  }
108  return false;
109}
110
111}  // namespace __asan
112
113#endif  // ASAN_MAPPING_H
114