asan_mapping.h revision 24861607cb3c606ad46e724456eb851558c85330 
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// Typical shadow mapping on Linux/x86_64 with SHADOW_OFFSET == 0x00007fff8000:
23// || `[0x10007fff8000, 0x7fffffffffff]` || HighMem    ||
24// || `[0x02008fff7000, 0x10007fff7fff]` || HighShadow ||
25// || `[0x00008fff7000, 0x02008fff6fff]` || ShadowGap  ||
26// || `[0x00007fff8000, 0x00008fff6fff]` || LowShadow  ||
27// || `[0x000000000000, 0x00007fff7fff]` || LowMem     ||
28//
29// When SHADOW_OFFSET is zero (-pie):
30// || `[0x100000000000, 0x7fffffffffff]` || HighMem    ||
31// || `[0x020000000000, 0x0fffffffffff]` || HighShadow ||
32// || `[0x000000040000, 0x01ffffffffff]` || ShadowGap  ||
33//
34// Special case when something is already mapped between
35// 0x003000000000 and 0x005000000000 (e.g. when prelink is installed):
36// || `[0x10007fff8000, 0x7fffffffffff]` || HighMem    ||
37// || `[0x02008fff7000, 0x10007fff7fff]` || HighShadow ||
38// || `[0x005000000000, 0x02008fff6fff]` || ShadowGap3 ||
39// || `[0x003000000000, 0x004fffffffff]` || MidMem     ||
40// || `[0x000a7fff8000, 0x002fffffffff]` || ShadowGap2 ||
41// || `[0x00067fff8000, 0x000a7fff7fff]` || MidShadow  ||
42// || `[0x00008fff7000, 0x00067fff7fff]` || ShadowGap  ||
43// || `[0x00007fff8000, 0x00008fff6fff]` || LowShadow  ||
44// || `[0x000000000000, 0x00007fff7fff]` || LowMem     ||
45//
46// Default Linux/i386 mapping:
47// || `[0x40000000, 0xffffffff]` || HighMem    ||
48// || `[0x28000000, 0x3fffffff]` || HighShadow ||
49// || `[0x24000000, 0x27ffffff]` || ShadowGap  ||
50// || `[0x20000000, 0x23ffffff]` || LowShadow  ||
51// || `[0x00000000, 0x1fffffff]` || LowMem     ||
52//
53// Default Linux/MIPS mapping:
54// || `[0x2aaa8000, 0xffffffff]` || HighMem    ||
55// || `[0x0fffd000, 0x2aaa7fff]` || HighShadow ||
56// || `[0x0bffd000, 0x0fffcfff]` || ShadowGap  ||
57// || `[0x0aaa8000, 0x0bffcfff]` || LowShadow  ||
58// || `[0x00000000, 0x0aaa7fff]` || LowMem     ||
59
60static const u64 kDefaultShadowScale = 3;
61static const u64 kDefaultShadowOffset32 = 1ULL << 29;
62static const u64 kDefaultShadowOffset64 = 1ULL << 44;
63static const u64 kDefaultShort64bitShadowOffset = 0x7FFF8000;  // < 2G.
64static const u64 kMIPS32_ShadowOffset32 = 0x0aaa8000;
65
66#if ASAN_FLEXIBLE_MAPPING_AND_OFFSET == 1
67extern SANITIZER_INTERFACE_ATTRIBUTE uptr __asan_mapping_scale;
68extern SANITIZER_INTERFACE_ATTRIBUTE uptr __asan_mapping_offset;
69# define SHADOW_SCALE (__asan_mapping_scale)
70# define SHADOW_OFFSET (__asan_mapping_offset)
71#else
72# define SHADOW_SCALE kDefaultShadowScale
73# if SANITIZER_ANDROID
74#  define SHADOW_OFFSET (0)
75# else
76#  if SANITIZER_WORDSIZE == 32
77#   if defined(__mips__)
78#     define SHADOW_OFFSET kMIPS32_ShadowOffset32
79#   else
80#     define SHADOW_OFFSET kDefaultShadowOffset32
81#   endif
82#  else
83#   if SANITIZER_MAC
84#    define SHADOW_OFFSET kDefaultShadowOffset64
85#   else
86#    define SHADOW_OFFSET kDefaultShort64bitShadowOffset
87#   endif
88#  endif
89# endif
90#endif  // ASAN_FLEXIBLE_MAPPING_AND_OFFSET
91
92#define SHADOW_GRANULARITY (1ULL << SHADOW_SCALE)
93#define MEM_TO_SHADOW(mem) (((mem) >> SHADOW_SCALE) + (SHADOW_OFFSET))
94#define SHADOW_TO_MEM(shadow) (((shadow) - SHADOW_OFFSET) << SHADOW_SCALE)
95
96#define kLowMemBeg      0
97#define kLowMemEnd      (SHADOW_OFFSET ? SHADOW_OFFSET - 1 : 0)
98
99#define kLowShadowBeg   SHADOW_OFFSET
100#define kLowShadowEnd   MEM_TO_SHADOW(kLowMemEnd)
101
102#define kHighMemBeg     (MEM_TO_SHADOW(kHighMemEnd) + 1)
103
104#define kHighShadowBeg  MEM_TO_SHADOW(kHighMemBeg)
105#define kHighShadowEnd  MEM_TO_SHADOW(kHighMemEnd)
106
107# define kMidShadowBeg MEM_TO_SHADOW(kMidMemBeg)
108# define kMidShadowEnd MEM_TO_SHADOW(kMidMemEnd)
109
110// With the zero shadow base we can not actually map pages starting from 0.
111// This constant is somewhat arbitrary.
112#define kZeroBaseShadowStart (1 << 18)
113
114#define kShadowGapBeg   (kLowShadowEnd ? kLowShadowEnd + 1 \
115                                       : kZeroBaseShadowStart)
116#define kShadowGapEnd   ((kMidMemBeg ? kMidShadowBeg : kHighShadowBeg) - 1)
117
118#define kShadowGap2Beg (kMidMemBeg ? kMidShadowEnd + 1 : 0)
119#define kShadowGap2End (kMidMemBeg ? kMidMemBeg - 1 : 0)
120
121#define kShadowGap3Beg (kMidMemBeg ? kMidMemEnd + 1 : 0)
122#define kShadowGap3End (kMidMemBeg ? kHighShadowBeg - 1 : 0)
123
124#define DO_ASAN_MAPPING_PROFILE 0  // Set to 1 to profile the functions below.
125
126#if DO_ASAN_MAPPING_PROFILE
127# define PROFILE_ASAN_MAPPING() AsanMappingProfile[__LINE__]++;
128#else
129# define PROFILE_ASAN_MAPPING()
130#endif
131
132// If 1, all shadow boundaries are constants.
133// Don't set to 1 other than for testing.
134#define ASAN_FIXED_MAPPING 0
135
136namespace __asan {
137
138extern uptr AsanMappingProfile[];
139
140#if ASAN_FIXED_MAPPING
141// Fixed mapping for 64-bit Linux. Mostly used for performance comparison
142// with non-fixed mapping. As of r175253 (Feb 2013) the performance
143// difference between fixed and non-fixed mapping is below the noise level.
144static uptr kHighMemEnd = 0x7fffffffffffULL;
145static uptr kMidMemBeg =    0x3000000000ULL;
146static uptr kMidMemEnd =    0x4fffffffffULL;
147#else
148extern uptr kHighMemEnd, kMidMemBeg, kMidMemEnd;  // Initialized in __asan_init.
149#endif
150
151static inline bool AddrIsInLowMem(uptr a) {
152  PROFILE_ASAN_MAPPING();
153  return a < kLowMemEnd;
154}
155
156static inline bool AddrIsInLowShadow(uptr a) {
157  PROFILE_ASAN_MAPPING();
158  return a >= kLowShadowBeg && a <= kLowShadowEnd;
159}
160
161static inline bool AddrIsInHighMem(uptr a) {
162  PROFILE_ASAN_MAPPING();
163  return a >= kHighMemBeg && a <= kHighMemEnd;
164}
165
166static inline bool AddrIsInMidMem(uptr a) {
167  PROFILE_ASAN_MAPPING();
168  return kMidMemBeg && a >= kMidMemBeg && a <= kMidMemEnd;
169}
170
171static inline bool AddrIsInMem(uptr a) {
172  PROFILE_ASAN_MAPPING();
173  return AddrIsInLowMem(a) || AddrIsInMidMem(a) || AddrIsInHighMem(a);
174}
175
176static inline uptr MemToShadow(uptr p) {
177  PROFILE_ASAN_MAPPING();
178  CHECK(AddrIsInMem(p));
179  return MEM_TO_SHADOW(p);
180}
181
182static inline bool AddrIsInHighShadow(uptr a) {
183  PROFILE_ASAN_MAPPING();
184  return a >= kHighShadowBeg && a <= kHighMemEnd;
185}
186
187static inline bool AddrIsInMidShadow(uptr a) {
188  PROFILE_ASAN_MAPPING();
189  return kMidMemBeg && a >= kMidShadowBeg && a <= kMidMemEnd;
190}
191
192static inline bool AddrIsInShadow(uptr a) {
193  PROFILE_ASAN_MAPPING();
194  return AddrIsInLowShadow(a) || AddrIsInMidShadow(a) || AddrIsInHighShadow(a);
195}
196
197static inline bool AddrIsInShadowGap(uptr a) {
198  PROFILE_ASAN_MAPPING();
199  if (kMidMemBeg) {
200    if (a <= kShadowGapEnd)
201      return SHADOW_OFFSET == 0 || a >= kShadowGapBeg;
202    return (a >= kShadowGap2Beg && a <= kShadowGap2End) ||
203           (a >= kShadowGap3Beg && a <= kShadowGap3End);
204  }
205  // In zero-based shadow mode we treat addresses near zero as addresses
206  // in shadow gap as well.
207  if (SHADOW_OFFSET == 0)
208    return a <= kShadowGapEnd;
209  return a >= kShadowGapBeg && a <= kShadowGapEnd;
210}
211
212static inline bool AddrIsAlignedByGranularity(uptr a) {
213  PROFILE_ASAN_MAPPING();
214  return (a & (SHADOW_GRANULARITY - 1)) == 0;
215}
216
217static inline bool AddressIsPoisoned(uptr a) {
218  PROFILE_ASAN_MAPPING();
219  const uptr kAccessSize = 1;
220  u8 *shadow_address = (u8*)MEM_TO_SHADOW(a);
221  s8 shadow_value = *shadow_address;
222  if (shadow_value) {
223    u8 last_accessed_byte = (a & (SHADOW_GRANULARITY - 1))
224                                 + kAccessSize - 1;
225    return (last_accessed_byte >= shadow_value);
226  }
227  return false;
228}
229
230// Must be after all calls to PROFILE_ASAN_MAPPING().
231static const uptr kAsanMappingProfileSize = __LINE__;
232
233}  // namespace __asan
234
235#endif  // ASAN_MAPPING_H
236