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
61 extern SANITIZER_INTERFACE_ATTRIBUTE uptr __asan_mapping_scale;
62 extern 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
135 namespace __asan {
136
137 extern 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.
143 static uptr kHighMemEnd = 0x7fffffffffffULL;
144 static uptr kMidMemBeg = 0x3000000000ULL;
145 static uptr kMidMemEnd = 0x4fffffffffULL;
146 #else
147 SANITIZER_INTERFACE_ATTRIBUTE
148 extern uptr kHighMemEnd, kMidMemBeg, kMidMemEnd; // Initialized in __asan_init.
149 #endif
150
AddrIsInLowMem(uptr a)151 static inline bool AddrIsInLowMem(uptr a) {
152 PROFILE_ASAN_MAPPING();
153 return a < kLowMemEnd;
154 }
155
AddrIsInLowShadow(uptr a)156 static inline bool AddrIsInLowShadow(uptr a) {
157 PROFILE_ASAN_MAPPING();
158 return a >= kLowShadowBeg && a <= kLowShadowEnd;
159 }
160
AddrIsInHighMem(uptr a)161 static inline bool AddrIsInHighMem(uptr a) {
162 PROFILE_ASAN_MAPPING();
163 return a >= kHighMemBeg && a <= kHighMemEnd;
164 }
165
AddrIsInMidMem(uptr a)166 static inline bool AddrIsInMidMem(uptr a) {
167 PROFILE_ASAN_MAPPING();
168 return kMidMemBeg && a >= kMidMemBeg && a <= kMidMemEnd;
169 }
170
AddrIsInMem(uptr a)171 static inline bool AddrIsInMem(uptr a) {
172 PROFILE_ASAN_MAPPING();
173 return AddrIsInLowMem(a) || AddrIsInMidMem(a) || AddrIsInHighMem(a);
174 }
175
MemToShadow(uptr p)176 static inline uptr MemToShadow(uptr p) {
177 PROFILE_ASAN_MAPPING();
178 CHECK(AddrIsInMem(p));
179 return MEM_TO_SHADOW(p);
180 }
181
AddrIsInHighShadow(uptr a)182 static inline bool AddrIsInHighShadow(uptr a) {
183 PROFILE_ASAN_MAPPING();
184 return a >= kHighShadowBeg && a <= kHighMemEnd;
185 }
186
AddrIsInMidShadow(uptr a)187 static inline bool AddrIsInMidShadow(uptr a) {
188 PROFILE_ASAN_MAPPING();
189 return kMidMemBeg && a >= kMidShadowBeg && a <= kMidMemEnd;
190 }
191
AddrIsInShadow(uptr a)192 static inline bool AddrIsInShadow(uptr a) {
193 PROFILE_ASAN_MAPPING();
194 return AddrIsInLowShadow(a) || AddrIsInMidShadow(a) || AddrIsInHighShadow(a);
195 }
196
AddrIsInShadowGap(uptr a)197 static 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
AddrIsAlignedByGranularity(uptr a)212 static inline bool AddrIsAlignedByGranularity(uptr a) {
213 PROFILE_ASAN_MAPPING();
214 return (a & (SHADOW_GRANULARITY - 1)) == 0;
215 }
216
AddressIsPoisoned(uptr a)217 static 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().
231 static const uptr kAsanMappingProfileSize = __LINE__;
232
233 } // namespace __asan
234
235 #endif // ASAN_MAPPING_H
236