asan_mapping.h revision 40527a579131210fcfa2373620a0c2200800e7c4 
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
60#if ASAN_FLEXIBLE_MAPPING_AND_OFFSET == 1
61extern SANITIZER_INTERFACE_ATTRIBUTE uptr __asan_mapping_scale;
62extern SANITIZER_INTERFACE_ATTRIBUTE uptr __asan_mapping_offset;
63# define SHADOW_SCALE (__asan_mapping_scale)
64# define SHADOW_OFFSET (__asan_mapping_offset)
65#else
66# if SANITIZER_ANDROID
67#  define SHADOW_SCALE (3)
68#  define SHADOW_OFFSET (0)
69# else
70#  define SHADOW_SCALE (3)
71#  if SANITIZER_WORDSIZE == 32
72#   if defined(__mips__)
73#     define SHADOW_OFFSET 0x0aaa8000
74#   else
75#     define SHADOW_OFFSET (1 << 29)
76#   endif
77#  else
78#   if defined(__powerpc64__)
79#    define SHADOW_OFFSET (1ULL << 41)
80#   else
81#    if SANITIZER_MAC
82#     define SHADOW_OFFSET (1ULL << 44)
83#    else
84#     define SHADOW_OFFSET 0x7fff8000ULL
85#    endif
86#   endif
87#  endif
88# endif
89#endif  // ASAN_FLEXIBLE_MAPPING_AND_OFFSET
90
91#define SHADOW_GRANULARITY (1ULL << SHADOW_SCALE)
92#define MEM_TO_SHADOW(mem) (((mem) >> SHADOW_SCALE) + (SHADOW_OFFSET))
93#define SHADOW_TO_MEM(shadow) (((shadow) - SHADOW_OFFSET) << SHADOW_SCALE)
94
95#define kLowMemBeg      0
96#define kLowMemEnd      (SHADOW_OFFSET ? SHADOW_OFFSET - 1 : 0)
97
98#define kLowShadowBeg   SHADOW_OFFSET
99#define kLowShadowEnd   MEM_TO_SHADOW(kLowMemEnd)
100
101#define kHighMemBeg     (MEM_TO_SHADOW(kHighMemEnd) + 1)
102
103#define kHighShadowBeg  MEM_TO_SHADOW(kHighMemBeg)
104#define kHighShadowEnd  MEM_TO_SHADOW(kHighMemEnd)
105
106# define kMidShadowBeg MEM_TO_SHADOW(kMidMemBeg)
107# define kMidShadowEnd MEM_TO_SHADOW(kMidMemEnd)
108
109// With the zero shadow base we can not actually map pages starting from 0.
110// This constant is somewhat arbitrary.
111#define kZeroBaseShadowStart (1 << 18)
112
113#define kShadowGapBeg   (kLowShadowEnd ? kLowShadowEnd + 1 \
114                                       : kZeroBaseShadowStart)
115#define kShadowGapEnd   ((kMidMemBeg ? kMidShadowBeg : kHighShadowBeg) - 1)
116
117#define kShadowGap2Beg (kMidMemBeg ? kMidShadowEnd + 1 : 0)
118#define kShadowGap2End (kMidMemBeg ? kMidMemBeg - 1 : 0)
119
120#define kShadowGap3Beg (kMidMemBeg ? kMidMemEnd + 1 : 0)
121#define kShadowGap3End (kMidMemBeg ? kHighShadowBeg - 1 : 0)
122
123#define DO_ASAN_MAPPING_PROFILE 0  // Set to 1 to profile the functions below.
124
125#if DO_ASAN_MAPPING_PROFILE
126# define PROFILE_ASAN_MAPPING() AsanMappingProfile[__LINE__]++;
127#else
128# define PROFILE_ASAN_MAPPING()
129#endif
130
131// If 1, all shadow boundaries are constants.
132// Don't set to 1 other than for testing.
133#define ASAN_FIXED_MAPPING 0
134
135namespace __asan {
136
137extern uptr AsanMappingProfile[];
138
139#if ASAN_FIXED_MAPPING
140// Fixed mapping for 64-bit Linux. Mostly used for performance comparison
141// with non-fixed mapping. As of r175253 (Feb 2013) the performance
142// difference between fixed and non-fixed mapping is below the noise level.
143static uptr kHighMemEnd = 0x7fffffffffffULL;
144static uptr kMidMemBeg =    0x3000000000ULL;
145static uptr kMidMemEnd =    0x4fffffffffULL;
146#else
147SANITIZER_INTERFACE_ATTRIBUTE
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