asan_mapping.h revision 22e21b044c9337a2fa921f268b7d221c693ad78b 
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 kPPC64_ShadowOffset64 = 1ULL << 41;
65static const u64 kMIPS32_ShadowOffset32 = 0x0aaa8000;
66
67#if ASAN_FLEXIBLE_MAPPING_AND_OFFSET == 1
68extern SANITIZER_INTERFACE_ATTRIBUTE uptr __asan_mapping_scale;
69extern SANITIZER_INTERFACE_ATTRIBUTE uptr __asan_mapping_offset;
70# define SHADOW_SCALE (__asan_mapping_scale)
71# define SHADOW_OFFSET (__asan_mapping_offset)
72#else
73# define SHADOW_SCALE kDefaultShadowScale
74# if SANITIZER_ANDROID
75#  define SHADOW_OFFSET (0)
76# else
77#  if SANITIZER_WORDSIZE == 32
78#   if defined(__mips__)
79#     define SHADOW_OFFSET kMIPS32_ShadowOffset32
80#   else
81#     define SHADOW_OFFSET kDefaultShadowOffset32
82#   endif
83#  else
84#   if defined(__powerpc64__)
85#    define SHADOW_OFFSET kPPC64_ShadowOffset64
86#   elif SANITIZER_MAC
87#    define SHADOW_OFFSET kDefaultShadowOffset64
88#   else
89#    define SHADOW_OFFSET kDefaultShort64bitShadowOffset
90#   endif
91#  endif
92# endif
93#endif  // ASAN_FLEXIBLE_MAPPING_AND_OFFSET
94
95#define SHADOW_GRANULARITY (1ULL << SHADOW_SCALE)
96#define MEM_TO_SHADOW(mem) (((mem) >> SHADOW_SCALE) + (SHADOW_OFFSET))
97#define SHADOW_TO_MEM(shadow) (((shadow) - SHADOW_OFFSET) << SHADOW_SCALE)
98
99#define kLowMemBeg      0
100#define kLowMemEnd      (SHADOW_OFFSET ? SHADOW_OFFSET - 1 : 0)
101
102#define kLowShadowBeg   SHADOW_OFFSET
103#define kLowShadowEnd   MEM_TO_SHADOW(kLowMemEnd)
104
105#define kHighMemBeg     (MEM_TO_SHADOW(kHighMemEnd) + 1)
106
107#define kHighShadowBeg  MEM_TO_SHADOW(kHighMemBeg)
108#define kHighShadowEnd  MEM_TO_SHADOW(kHighMemEnd)
109
110# define kMidShadowBeg MEM_TO_SHADOW(kMidMemBeg)
111# define kMidShadowEnd MEM_TO_SHADOW(kMidMemEnd)
112
113// With the zero shadow base we can not actually map pages starting from 0.
114// This constant is somewhat arbitrary.
115#define kZeroBaseShadowStart (1 << 18)
116
117#define kShadowGapBeg   (kLowShadowEnd ? kLowShadowEnd + 1 \
118                                       : kZeroBaseShadowStart)
119#define kShadowGapEnd   ((kMidMemBeg ? kMidShadowBeg : kHighShadowBeg) - 1)
120
121#define kShadowGap2Beg (kMidMemBeg ? kMidShadowEnd + 1 : 0)
122#define kShadowGap2End (kMidMemBeg ? kMidMemBeg - 1 : 0)
123
124#define kShadowGap3Beg (kMidMemBeg ? kMidMemEnd + 1 : 0)
125#define kShadowGap3End (kMidMemBeg ? kHighShadowBeg - 1 : 0)
126
127#define DO_ASAN_MAPPING_PROFILE 0  // Set to 1 to profile the functions below.
128
129#if DO_ASAN_MAPPING_PROFILE
130# define PROFILE_ASAN_MAPPING() AsanMappingProfile[__LINE__]++;
131#else
132# define PROFILE_ASAN_MAPPING()
133#endif
134
135// If 1, all shadow boundaries are constants.
136// Don't set to 1 other than for testing.
137#define ASAN_FIXED_MAPPING 0
138
139namespace __asan {
140
141extern uptr AsanMappingProfile[];
142
143#if ASAN_FIXED_MAPPING
144// Fixed mapping for 64-bit Linux. Mostly used for performance comparison
145// with non-fixed mapping. As of r175253 (Feb 2013) the performance
146// difference between fixed and non-fixed mapping is below the noise level.
147static uptr kHighMemEnd = 0x7fffffffffffULL;
148static uptr kMidMemBeg =    0x3000000000ULL;
149static uptr kMidMemEnd =    0x4fffffffffULL;
150#else
151SANITIZER_INTERFACE_ATTRIBUTE
152extern uptr kHighMemEnd, kMidMemBeg, kMidMemEnd;  // Initialized in __asan_init.
153#endif
154
155static inline bool AddrIsInLowMem(uptr a) {
156  PROFILE_ASAN_MAPPING();
157  return a < kLowMemEnd;
158}
159
160static inline bool AddrIsInLowShadow(uptr a) {
161  PROFILE_ASAN_MAPPING();
162  return a >= kLowShadowBeg && a <= kLowShadowEnd;
163}
164
165static inline bool AddrIsInHighMem(uptr a) {
166  PROFILE_ASAN_MAPPING();
167  return a >= kHighMemBeg && a <= kHighMemEnd;
168}
169
170static inline bool AddrIsInMidMem(uptr a) {
171  PROFILE_ASAN_MAPPING();
172  return kMidMemBeg && a >= kMidMemBeg && a <= kMidMemEnd;
173}
174
175static inline bool AddrIsInMem(uptr a) {
176  PROFILE_ASAN_MAPPING();
177  return AddrIsInLowMem(a) || AddrIsInMidMem(a) || AddrIsInHighMem(a);
178}
179
180static inline uptr MemToShadow(uptr p) {
181  PROFILE_ASAN_MAPPING();
182  CHECK(AddrIsInMem(p));
183  return MEM_TO_SHADOW(p);
184}
185
186static inline bool AddrIsInHighShadow(uptr a) {
187  PROFILE_ASAN_MAPPING();
188  return a >= kHighShadowBeg && a <= kHighMemEnd;
189}
190
191static inline bool AddrIsInMidShadow(uptr a) {
192  PROFILE_ASAN_MAPPING();
193  return kMidMemBeg && a >= kMidShadowBeg && a <= kMidMemEnd;
194}
195
196static inline bool AddrIsInShadow(uptr a) {
197  PROFILE_ASAN_MAPPING();
198  return AddrIsInLowShadow(a) || AddrIsInMidShadow(a) || AddrIsInHighShadow(a);
199}
200
201static inline bool AddrIsInShadowGap(uptr a) {
202  PROFILE_ASAN_MAPPING();
203  if (kMidMemBeg) {
204    if (a <= kShadowGapEnd)
205      return SHADOW_OFFSET == 0 || a >= kShadowGapBeg;
206    return (a >= kShadowGap2Beg && a <= kShadowGap2End) ||
207           (a >= kShadowGap3Beg && a <= kShadowGap3End);
208  }
209  // In zero-based shadow mode we treat addresses near zero as addresses
210  // in shadow gap as well.
211  if (SHADOW_OFFSET == 0)
212    return a <= kShadowGapEnd;
213  return a >= kShadowGapBeg && a <= kShadowGapEnd;
214}
215
216static inline bool AddrIsAlignedByGranularity(uptr a) {
217  PROFILE_ASAN_MAPPING();
218  return (a & (SHADOW_GRANULARITY - 1)) == 0;
219}
220
221static inline bool AddressIsPoisoned(uptr a) {
222  PROFILE_ASAN_MAPPING();
223  const uptr kAccessSize = 1;
224  u8 *shadow_address = (u8*)MEM_TO_SHADOW(a);
225  s8 shadow_value = *shadow_address;
226  if (shadow_value) {
227    u8 last_accessed_byte = (a & (SHADOW_GRANULARITY - 1))
228                                 + kAccessSize - 1;
229    return (last_accessed_byte >= shadow_value);
230  }
231  return false;
232}
233
234// Must be after all calls to PROFILE_ASAN_MAPPING().
235static const uptr kAsanMappingProfileSize = __LINE__;
236
237}  // namespace __asan
238
239#endif  // ASAN_MAPPING_H
240