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
52 extern SANITIZER_INTERFACE_ATTRIBUTE uptr __asan_mapping_scale;
53 extern 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
122 namespace __asan {
123
124 extern 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.
130 static uptr kHighMemEnd = 0x7fffffffffffULL;
131 static uptr kMidMemBeg = 0x3000000000ULL;
132 static uptr kMidMemEnd = 0x4fffffffffULL;
133 #else
134 SANITIZER_INTERFACE_ATTRIBUTE
135 extern uptr kHighMemEnd, kMidMemBeg, kMidMemEnd; // Initialized in __asan_init.
136 #endif
137
AddrIsInLowMem(uptr a)138 static inline bool AddrIsInLowMem(uptr a) {
139 PROFILE_ASAN_MAPPING();
140 return a < kLowMemEnd;
141 }
142
AddrIsInLowShadow(uptr a)143 static inline bool AddrIsInLowShadow(uptr a) {
144 PROFILE_ASAN_MAPPING();
145 return a >= kLowShadowBeg && a <= kLowShadowEnd;
146 }
147
AddrIsInHighMem(uptr a)148 static inline bool AddrIsInHighMem(uptr a) {
149 PROFILE_ASAN_MAPPING();
150 return a >= kHighMemBeg && a <= kHighMemEnd;
151 }
152
AddrIsInMidMem(uptr a)153 static inline bool AddrIsInMidMem(uptr a) {
154 PROFILE_ASAN_MAPPING();
155 return kMidMemBeg && a >= kMidMemBeg && a <= kMidMemEnd;
156 }
157
AddrIsInMem(uptr a)158 static inline bool AddrIsInMem(uptr a) {
159 PROFILE_ASAN_MAPPING();
160 return AddrIsInLowMem(a) || AddrIsInMidMem(a) || AddrIsInHighMem(a);
161 }
162
MemToShadow(uptr p)163 static inline uptr MemToShadow(uptr p) {
164 PROFILE_ASAN_MAPPING();
165 CHECK(AddrIsInMem(p));
166 return MEM_TO_SHADOW(p);
167 }
168
AddrIsInHighShadow(uptr a)169 static inline bool AddrIsInHighShadow(uptr a) {
170 PROFILE_ASAN_MAPPING();
171 return a >= kHighShadowBeg && a <= kHighMemEnd;
172 }
173
AddrIsInMidShadow(uptr a)174 static inline bool AddrIsInMidShadow(uptr a) {
175 PROFILE_ASAN_MAPPING();
176 return kMidMemBeg && a >= kMidShadowBeg && a <= kMidMemEnd;
177 }
178
AddrIsInShadow(uptr a)179 static inline bool AddrIsInShadow(uptr a) {
180 PROFILE_ASAN_MAPPING();
181 return AddrIsInLowShadow(a) || AddrIsInMidShadow(a) || AddrIsInHighShadow(a);
182 }
183
AddrIsInShadowGap(uptr a)184 static 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
AddrIsAlignedByGranularity(uptr a)199 static inline bool AddrIsAlignedByGranularity(uptr a) {
200 PROFILE_ASAN_MAPPING();
201 return (a & (SHADOW_GRANULARITY - 1)) == 0;
202 }
203
AddressIsPoisoned(uptr a)204 static 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().
218 static const uptr kAsanMappingProfileSize = __LINE__;
219
220 } // namespace __asan
221
222 #endif // ASAN_MAPPING_H
223