asan_mapping.h revision 1.1 
1//===-- asan_mapping.h ------------------------------------------*- C++ -*-===//
2//
3// This file is distributed under the University of Illinois Open Source
4// License. See LICENSE.TXT for details.
5//
6//===----------------------------------------------------------------------===//
7//
8// This file is a part of AddressSanitizer, an address sanity checker.
9//
10// Defines ASan memory mapping.
11//===----------------------------------------------------------------------===//
12#ifndef ASAN_MAPPING_H
13#define ASAN_MAPPING_H
14
15#include "asan_internal.h"
16
17// The full explanation of the memory mapping could be found here:
18// http://code.google.com/p/address-sanitizer/wiki/AddressSanitizerAlgorithm
19//
20// Typical shadow mapping on Linux/x86_64 with SHADOW_OFFSET == 0x00007fff8000:
21// || `[0x10007fff8000, 0x7fffffffffff]` || HighMem    ||
22// || `[0x02008fff7000, 0x10007fff7fff]` || HighShadow ||
23// || `[0x00008fff7000, 0x02008fff6fff]` || ShadowGap  ||
24// || `[0x00007fff8000, 0x00008fff6fff]` || LowShadow  ||
25// || `[0x000000000000, 0x00007fff7fff]` || LowMem     ||
26//
27// When SHADOW_OFFSET is zero (-pie):
28// || `[0x100000000000, 0x7fffffffffff]` || HighMem    ||
29// || `[0x020000000000, 0x0fffffffffff]` || HighShadow ||
30// || `[0x000000040000, 0x01ffffffffff]` || ShadowGap  ||
31//
32// Special case when something is already mapped between
33// 0x003000000000 and 0x005000000000 (e.g. when prelink is installed):
34// || `[0x10007fff8000, 0x7fffffffffff]` || HighMem    ||
35// || `[0x02008fff7000, 0x10007fff7fff]` || HighShadow ||
36// || `[0x005000000000, 0x02008fff6fff]` || ShadowGap3 ||
37// || `[0x003000000000, 0x004fffffffff]` || MidMem     ||
38// || `[0x000a7fff8000, 0x002fffffffff]` || ShadowGap2 ||
39// || `[0x00067fff8000, 0x000a7fff7fff]` || MidShadow  ||
40// || `[0x00008fff7000, 0x00067fff7fff]` || ShadowGap  ||
41// || `[0x00007fff8000, 0x00008fff6fff]` || LowShadow  ||
42// || `[0x000000000000, 0x00007fff7fff]` || LowMem     ||
43//
44// Default Linux/i386 mapping:
45// || `[0x40000000, 0xffffffff]` || HighMem    ||
46// || `[0x28000000, 0x3fffffff]` || HighShadow ||
47// || `[0x24000000, 0x27ffffff]` || ShadowGap  ||
48// || `[0x20000000, 0x23ffffff]` || LowShadow  ||
49// || `[0x00000000, 0x1fffffff]` || LowMem     ||
50
51#if ASAN_FLEXIBLE_MAPPING_AND_OFFSET == 1
52extern SANITIZER_INTERFACE_ATTRIBUTE uptr __asan_mapping_scale;
53extern SANITIZER_INTERFACE_ATTRIBUTE uptr __asan_mapping_offset;
54# define SHADOW_SCALE (__asan_mapping_scale)
55# define SHADOW_OFFSET (__asan_mapping_offset)
56#else
57# if ASAN_ANDROID
58#  define SHADOW_SCALE (3)
59#  define SHADOW_OFFSET (0)
60# else
61#  define SHADOW_SCALE (3)
62#  if SANITIZER_WORDSIZE == 32
63#   define SHADOW_OFFSET (1 << 29)
64#  else
65#   if defined(__powerpc64__)
66#    define SHADOW_OFFSET (1ULL << 41)
67#   else
68#    if ASAN_MAC
69#     define SHADOW_OFFSET (1ULL << 44)
70#    else
71#     define SHADOW_OFFSET 0x7fff8000ULL
72#    endif
73#   endif
74#  endif
75# endif
76#endif  // ASAN_FLEXIBLE_MAPPING_AND_OFFSET
77
78#define SHADOW_GRANULARITY (1ULL << SHADOW_SCALE)
79#define MEM_TO_SHADOW(mem) (((mem) >> SHADOW_SCALE) + (SHADOW_OFFSET))
80#define SHADOW_TO_MEM(shadow) (((shadow) - SHADOW_OFFSET) << SHADOW_SCALE)
81
82#define kLowMemBeg      0
83#define kLowMemEnd      (SHADOW_OFFSET ? SHADOW_OFFSET - 1 : 0)
84
85#define kLowShadowBeg   SHADOW_OFFSET
86#define kLowShadowEnd   MEM_TO_SHADOW(kLowMemEnd)
87
88#define kHighMemBeg     (MEM_TO_SHADOW(kHighMemEnd) + 1)
89
90#define kHighShadowBeg  MEM_TO_SHADOW(kHighMemBeg)
91#define kHighShadowEnd  MEM_TO_SHADOW(kHighMemEnd)
92
93# define kMidShadowBeg MEM_TO_SHADOW(kMidMemBeg)
94# define kMidShadowEnd MEM_TO_SHADOW(kMidMemEnd)
95
96// With the zero shadow base we can not actually map pages starting from 0.
97// This constant is somewhat arbitrary.
98#define kZeroBaseShadowStart (1 << 18)
99
100#define kShadowGapBeg   (kLowShadowEnd ? kLowShadowEnd + 1 \
101                                       : kZeroBaseShadowStart)
102#define kShadowGapEnd   ((kMidMemBeg ? kMidShadowBeg : kHighShadowBeg) - 1)
103
104#define kShadowGap2Beg (kMidMemBeg ? kMidShadowEnd + 1 : 0)
105#define kShadowGap2End (kMidMemBeg ? kMidMemBeg - 1 : 0)
106
107#define kShadowGap3Beg (kMidMemBeg ? kMidMemEnd + 1 : 0)
108#define kShadowGap3End (kMidMemBeg ? kHighShadowBeg - 1 : 0)
109
110#define DO_ASAN_MAPPING_PROFILE 0  // Set to 1 to profile the functions below.
111
112#if DO_ASAN_MAPPING_PROFILE
113# define PROFILE_ASAN_MAPPING() AsanMappingProfile[__LINE__]++;
114#else
115# define PROFILE_ASAN_MAPPING()
116#endif
117
118// If 1, all shadow boundaries are constants.
119// Don't set to 1 other than for testing.
120#define ASAN_FIXED_MAPPING 0
121
122namespace __asan {
123
124extern uptr AsanMappingProfile[];
125
126#if ASAN_FIXED_MAPPING
127// Fixed mapping for 64-bit Linux. Mostly used for performance comparison
128// with non-fixed mapping. As of r175253 (Feb 2013) the performance
129// difference between fixed and non-fixed mapping is below the noise level.
130static uptr kHighMemEnd = 0x7fffffffffffULL;
131static uptr kMidMemBeg =    0x3000000000ULL;
132static uptr kMidMemEnd =    0x4fffffffffULL;
133#else
134SANITIZER_INTERFACE_ATTRIBUTE
135extern uptr kHighMemEnd, kMidMemBeg, kMidMemEnd;  // Initialized in __asan_init.
136#endif
137
138static inline bool AddrIsInLowMem(uptr a) {
139  PROFILE_ASAN_MAPPING();
140  return a < kLowMemEnd;
141}
142
143static inline bool AddrIsInLowShadow(uptr a) {
144  PROFILE_ASAN_MAPPING();
145  return a >= kLowShadowBeg && a <= kLowShadowEnd;
146}
147
148static inline bool AddrIsInHighMem(uptr a) {
149  PROFILE_ASAN_MAPPING();
150  return a >= kHighMemBeg && a <= kHighMemEnd;
151}
152
153static inline bool AddrIsInMidMem(uptr a) {
154  PROFILE_ASAN_MAPPING();
155  return kMidMemBeg && a >= kMidMemBeg && a <= kMidMemEnd;
156}
157
158static inline bool AddrIsInMem(uptr a) {
159  PROFILE_ASAN_MAPPING();
160  return AddrIsInLowMem(a) || AddrIsInMidMem(a) || AddrIsInHighMem(a);
161}
162
163static inline uptr MemToShadow(uptr p) {
164  PROFILE_ASAN_MAPPING();
165  CHECK(AddrIsInMem(p));
166  return MEM_TO_SHADOW(p);
167}
168
169static inline bool AddrIsInHighShadow(uptr a) {
170  PROFILE_ASAN_MAPPING();
171  return a >= kHighShadowBeg && a <= kHighMemEnd;
172}
173
174static inline bool AddrIsInMidShadow(uptr a) {
175  PROFILE_ASAN_MAPPING();
176  return kMidMemBeg && a >= kMidShadowBeg && a <= kMidMemEnd;
177}
178
179static inline bool AddrIsInShadow(uptr a) {
180  PROFILE_ASAN_MAPPING();
181  return AddrIsInLowShadow(a) || AddrIsInMidShadow(a) || AddrIsInHighShadow(a);
182}
183
184static inline bool AddrIsInShadowGap(uptr a) {
185  PROFILE_ASAN_MAPPING();
186  if (kMidMemBeg) {
187    if (a <= kShadowGapEnd)
188      return SHADOW_OFFSET == 0 || a >= kShadowGapBeg;
189    return (a >= kShadowGap2Beg && a <= kShadowGap2End) ||
190           (a >= kShadowGap3Beg && a <= kShadowGap3End);
191  }
192  // In zero-based shadow mode we treat addresses near zero as addresses
193  // in shadow gap as well.
194  if (SHADOW_OFFSET == 0)
195    return a <= kShadowGapEnd;
196  return a >= kShadowGapBeg && a <= kShadowGapEnd;
197}
198
199static inline bool AddrIsAlignedByGranularity(uptr a) {
200  PROFILE_ASAN_MAPPING();
201  return (a & (SHADOW_GRANULARITY - 1)) == 0;
202}
203
204static inline bool AddressIsPoisoned(uptr a) {
205  PROFILE_ASAN_MAPPING();
206  const uptr kAccessSize = 1;
207  u8 *shadow_address = (u8*)MEM_TO_SHADOW(a);
208  s8 shadow_value = *shadow_address;
209  if (shadow_value) {
210    u8 last_accessed_byte = (a & (SHADOW_GRANULARITY - 1))
211                                 + kAccessSize - 1;
212    return (last_accessed_byte >= shadow_value);
213  }
214  return false;
215}
216
217// Must be after all calls to PROFILE_ASAN_MAPPING().
218static const uptr kAsanMappingProfileSize = __LINE__;
219
220}  // namespace __asan
221
222#endif  // ASAN_MAPPING_H
223