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 #if ASAN_FLEXIBLE_MAPPING_AND_OFFSET == 1
54 extern SANITIZER_INTERFACE_ATTRIBUTE uptr __asan_mapping_scale;
55 extern SANITIZER_INTERFACE_ATTRIBUTE uptr __asan_mapping_offset;
56 # define SHADOW_SCALE (__asan_mapping_scale)
57 # define SHADOW_OFFSET (__asan_mapping_offset)
58 #else
59 # if ASAN_ANDROID
60 # define SHADOW_SCALE (3)
61 # define SHADOW_OFFSET (0)
62 # else
63 # define SHADOW_SCALE (3)
64 # if SANITIZER_WORDSIZE == 32
65 # define SHADOW_OFFSET (1 << 29)
66 # else
67 # if defined(__powerpc64__)
68 # define SHADOW_OFFSET (1ULL << 41)
69 # else
70 # if ASAN_MAC
71 # define SHADOW_OFFSET (1ULL << 44)
72 # else
73 # define SHADOW_OFFSET 0x7fff8000ULL
74 # endif
75 # endif
76 # endif
77 # endif
78 #endif // ASAN_FLEXIBLE_MAPPING_AND_OFFSET
79
80 #define SHADOW_GRANULARITY (1ULL << SHADOW_SCALE)
81 #define MEM_TO_SHADOW(mem) (((mem) >> SHADOW_SCALE) + (SHADOW_OFFSET))
82 #define SHADOW_TO_MEM(shadow) (((shadow) - SHADOW_OFFSET) << SHADOW_SCALE)
83
84 #define kLowMemBeg 0
85 #define kLowMemEnd (SHADOW_OFFSET ? SHADOW_OFFSET - 1 : 0)
86
87 #define kLowShadowBeg SHADOW_OFFSET
88 #define kLowShadowEnd MEM_TO_SHADOW(kLowMemEnd)
89
90 #define kHighMemBeg (MEM_TO_SHADOW(kHighMemEnd) + 1)
91
92 #define kHighShadowBeg MEM_TO_SHADOW(kHighMemBeg)
93 #define kHighShadowEnd MEM_TO_SHADOW(kHighMemEnd)
94
95 # define kMidShadowBeg MEM_TO_SHADOW(kMidMemBeg)
96 # define kMidShadowEnd MEM_TO_SHADOW(kMidMemEnd)
97
98 // With the zero shadow base we can not actually map pages starting from 0.
99 // This constant is somewhat arbitrary.
100 #define kZeroBaseShadowStart (1 << 18)
101
102 #define kShadowGapBeg (kLowShadowEnd ? kLowShadowEnd + 1 \
103 : kZeroBaseShadowStart)
104 #define kShadowGapEnd ((kMidMemBeg ? kMidShadowBeg : kHighShadowBeg) - 1)
105
106 #define kShadowGap2Beg (kMidMemBeg ? kMidShadowEnd + 1 : 0)
107 #define kShadowGap2End (kMidMemBeg ? kMidMemBeg - 1 : 0)
108
109 #define kShadowGap3Beg (kMidMemBeg ? kMidMemEnd + 1 : 0)
110 #define kShadowGap3End (kMidMemBeg ? kHighShadowBeg - 1 : 0)
111
112 #define DO_ASAN_MAPPING_PROFILE 0 // Set to 1 to profile the functions below.
113
114 #if DO_ASAN_MAPPING_PROFILE
115 # define PROFILE_ASAN_MAPPING() AsanMappingProfile[__LINE__]++;
116 #else
117 # define PROFILE_ASAN_MAPPING()
118 #endif
119
120 // If 1, all shadow boundaries are constants.
121 // Don't set to 1 other than for testing.
122 #define ASAN_FIXED_MAPPING 0
123
124 namespace __asan {
125
126 extern uptr AsanMappingProfile[];
127
128 #if ASAN_FIXED_MAPPING
129 // Fixed mapping for 64-bit Linux. Mostly used for performance comparison
130 // with non-fixed mapping. As of r175253 (Feb 2013) the performance
131 // difference between fixed and non-fixed mapping is below the noise level.
132 static uptr kHighMemEnd = 0x7fffffffffffULL;
133 static uptr kMidMemBeg = 0x3000000000ULL;
134 static uptr kMidMemEnd = 0x4fffffffffULL;
135 #else
136 SANITIZER_INTERFACE_ATTRIBUTE
137 extern uptr kHighMemEnd, kMidMemBeg, kMidMemEnd; // Initialized in __asan_init.
138 #endif
139
AddrIsInLowMem(uptr a)140 static inline bool AddrIsInLowMem(uptr a) {
141 PROFILE_ASAN_MAPPING();
142 return a < kLowMemEnd;
143 }
144
AddrIsInLowShadow(uptr a)145 static inline bool AddrIsInLowShadow(uptr a) {
146 PROFILE_ASAN_MAPPING();
147 return a >= kLowShadowBeg && a <= kLowShadowEnd;
148 }
149
AddrIsInHighMem(uptr a)150 static inline bool AddrIsInHighMem(uptr a) {
151 PROFILE_ASAN_MAPPING();
152 return a >= kHighMemBeg && a <= kHighMemEnd;
153 }
154
AddrIsInMidMem(uptr a)155 static inline bool AddrIsInMidMem(uptr a) {
156 PROFILE_ASAN_MAPPING();
157 return kMidMemBeg && a >= kMidMemBeg && a <= kMidMemEnd;
158 }
159
AddrIsInMem(uptr a)160 static inline bool AddrIsInMem(uptr a) {
161 PROFILE_ASAN_MAPPING();
162 return AddrIsInLowMem(a) || AddrIsInMidMem(a) || AddrIsInHighMem(a);
163 }
164
MemToShadow(uptr p)165 static inline uptr MemToShadow(uptr p) {
166 PROFILE_ASAN_MAPPING();
167 CHECK(AddrIsInMem(p));
168 return MEM_TO_SHADOW(p);
169 }
170
AddrIsInHighShadow(uptr a)171 static inline bool AddrIsInHighShadow(uptr a) {
172 PROFILE_ASAN_MAPPING();
173 return a >= kHighShadowBeg && a <= kHighMemEnd;
174 }
175
AddrIsInMidShadow(uptr a)176 static inline bool AddrIsInMidShadow(uptr a) {
177 PROFILE_ASAN_MAPPING();
178 return kMidMemBeg && a >= kMidShadowBeg && a <= kMidMemEnd;
179 }
180
AddrIsInShadow(uptr a)181 static inline bool AddrIsInShadow(uptr a) {
182 PROFILE_ASAN_MAPPING();
183 return AddrIsInLowShadow(a) || AddrIsInMidShadow(a) || AddrIsInHighShadow(a);
184 }
185
AddrIsInShadowGap(uptr a)186 static inline bool AddrIsInShadowGap(uptr a) {
187 PROFILE_ASAN_MAPPING();
188 if (kMidMemBeg) {
189 if (a <= kShadowGapEnd)
190 return SHADOW_OFFSET == 0 || a >= kShadowGapBeg;
191 return (a >= kShadowGap2Beg && a <= kShadowGap2End) ||
192 (a >= kShadowGap3Beg && a <= kShadowGap3End);
193 }
194 // In zero-based shadow mode we treat addresses near zero as addresses
195 // in shadow gap as well.
196 if (SHADOW_OFFSET == 0)
197 return a <= kShadowGapEnd;
198 return a >= kShadowGapBeg && a <= kShadowGapEnd;
199 }
200
AddrIsAlignedByGranularity(uptr a)201 static inline bool AddrIsAlignedByGranularity(uptr a) {
202 PROFILE_ASAN_MAPPING();
203 return (a & (SHADOW_GRANULARITY - 1)) == 0;
204 }
205
AddressIsPoisoned(uptr a)206 static inline bool AddressIsPoisoned(uptr a) {
207 PROFILE_ASAN_MAPPING();
208 const uptr kAccessSize = 1;
209 u8 *shadow_address = (u8*)MEM_TO_SHADOW(a);
210 s8 shadow_value = *shadow_address;
211 if (shadow_value) {
212 u8 last_accessed_byte = (a & (SHADOW_GRANULARITY - 1))
213 + kAccessSize - 1;
214 return (last_accessed_byte >= shadow_value);
215 }
216 return false;
217 }
218
219 // Must be after all calls to PROFILE_ASAN_MAPPING().
220 static const uptr kAsanMappingProfileSize = __LINE__;
221
222 } // namespace __asan
223
224 #endif // ASAN_MAPPING_H
225