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 on x86_64 machine:
47 // || `[0x40000000, 0xffffffff]` || HighMem ||
48 // || `[0x28000000, 0x3fffffff]` || HighShadow ||
49 // || `[0x24000000, 0x27ffffff]` || ShadowGap ||
50 // || `[0x20000000, 0x23ffffff]` || LowShadow ||
51 // || `[0x00000000, 0x1fffffff]` || LowMem ||
52 //
53 // Default Linux/i386 mapping on i386 machine
54 // (addresses starting with 0xc0000000 are reserved
55 // for kernel and thus not sanitized):
56 // || `[0x38000000, 0xbfffffff]` || HighMem ||
57 // || `[0x27000000, 0x37ffffff]` || HighShadow ||
58 // || `[0x24000000, 0x26ffffff]` || ShadowGap ||
59 // || `[0x20000000, 0x23ffffff]` || LowShadow ||
60 // || `[0x00000000, 0x1fffffff]` || LowMem ||
61 //
62 // Default Linux/MIPS mapping:
63 // || `[0x2aaa8000, 0xffffffff]` || HighMem ||
64 // || `[0x0fffd000, 0x2aaa7fff]` || HighShadow ||
65 // || `[0x0bffd000, 0x0fffcfff]` || ShadowGap ||
66 // || `[0x0aaa8000, 0x0bffcfff]` || LowShadow ||
67 // || `[0x00000000, 0x0aaa7fff]` || LowMem ||
68 //
69 // Shadow mapping on FreeBSD/x86-64 with SHADOW_OFFSET == 0x400000000000:
70 // || `[0x500000000000, 0x7fffffffffff]` || HighMem ||
71 // || `[0x4a0000000000, 0x4fffffffffff]` || HighShadow ||
72 // || `[0x480000000000, 0x49ffffffffff]` || ShadowGap ||
73 // || `[0x400000000000, 0x47ffffffffff]` || LowShadow ||
74 // || `[0x000000000000, 0x3fffffffffff]` || LowMem ||
75 //
76 // Shadow mapping on FreeBSD/i386 with SHADOW_OFFSET == 0x40000000:
77 // || `[0x60000000, 0xffffffff]` || HighMem ||
78 // || `[0x4c000000, 0x5fffffff]` || HighShadow ||
79 // || `[0x48000000, 0x4bffffff]` || ShadowGap ||
80 // || `[0x40000000, 0x47ffffff]` || LowShadow ||
81 // || `[0x00000000, 0x3fffffff]` || LowMem ||
82
83 static const u64 kDefaultShadowScale = 3;
84 static const u64 kDefaultShadowOffset32 = 1ULL << 29; // 0x20000000
85 static const u64 kIosShadowOffset32 = 1ULL << 30; // 0x40000000
86 static const u64 kDefaultShadowOffset64 = 1ULL << 44;
87 static const u64 kDefaultShort64bitShadowOffset = 0x7FFF8000; // < 2G.
88 static const u64 kAArch64_ShadowOffset64 = 1ULL << 36;
89 static const u64 kMIPS32_ShadowOffset32 = 0x0aaa8000;
90 static const u64 kPPC64_ShadowOffset64 = 1ULL << 41;
91 static const u64 kFreeBSD_ShadowOffset32 = 1ULL << 30; // 0x40000000
92 static const u64 kFreeBSD_ShadowOffset64 = 1ULL << 46; // 0x400000000000
93
94 #define SHADOW_SCALE kDefaultShadowScale
95 #if SANITIZER_ANDROID
96 # define SHADOW_OFFSET (0)
97 #else
98 # if SANITIZER_WORDSIZE == 32
99 # if defined(__mips__)
100 # define SHADOW_OFFSET kMIPS32_ShadowOffset32
101 # elif SANITIZER_FREEBSD
102 # define SHADOW_OFFSET kFreeBSD_ShadowOffset32
103 # else
104 # if SANITIZER_IOS
105 # define SHADOW_OFFSET kIosShadowOffset32
106 # else
107 # define SHADOW_OFFSET kDefaultShadowOffset32
108 # endif
109 # endif
110 # else
111 # if defined(__aarch64__)
112 # define SHADOW_OFFSET kAArch64_ShadowOffset64
113 # elif defined(__powerpc64__)
114 # define SHADOW_OFFSET kPPC64_ShadowOffset64
115 # elif SANITIZER_FREEBSD
116 # define SHADOW_OFFSET kFreeBSD_ShadowOffset64
117 # elif SANITIZER_MAC
118 # define SHADOW_OFFSET kDefaultShadowOffset64
119 # else
120 # define SHADOW_OFFSET kDefaultShort64bitShadowOffset
121 # endif
122 # endif
123 #endif
124
125 #define SHADOW_GRANULARITY (1ULL << SHADOW_SCALE)
126 #define MEM_TO_SHADOW(mem) (((mem) >> SHADOW_SCALE) + (SHADOW_OFFSET))
127 #define SHADOW_TO_MEM(shadow) (((shadow) - SHADOW_OFFSET) << SHADOW_SCALE)
128
129 #define kLowMemBeg 0
130 #define kLowMemEnd (SHADOW_OFFSET ? SHADOW_OFFSET - 1 : 0)
131
132 #define kLowShadowBeg SHADOW_OFFSET
133 #define kLowShadowEnd MEM_TO_SHADOW(kLowMemEnd)
134
135 #define kHighMemBeg (MEM_TO_SHADOW(kHighMemEnd) + 1)
136
137 #define kHighShadowBeg MEM_TO_SHADOW(kHighMemBeg)
138 #define kHighShadowEnd MEM_TO_SHADOW(kHighMemEnd)
139
140 # define kMidShadowBeg MEM_TO_SHADOW(kMidMemBeg)
141 # define kMidShadowEnd MEM_TO_SHADOW(kMidMemEnd)
142
143 // With the zero shadow base we can not actually map pages starting from 0.
144 // This constant is somewhat arbitrary.
145 #define kZeroBaseShadowStart (1 << 18)
146
147 #define kShadowGapBeg (kLowShadowEnd ? kLowShadowEnd + 1 \
148 : kZeroBaseShadowStart)
149 #define kShadowGapEnd ((kMidMemBeg ? kMidShadowBeg : kHighShadowBeg) - 1)
150
151 #define kShadowGap2Beg (kMidMemBeg ? kMidShadowEnd + 1 : 0)
152 #define kShadowGap2End (kMidMemBeg ? kMidMemBeg - 1 : 0)
153
154 #define kShadowGap3Beg (kMidMemBeg ? kMidMemEnd + 1 : 0)
155 #define kShadowGap3End (kMidMemBeg ? kHighShadowBeg - 1 : 0)
156
157 #define DO_ASAN_MAPPING_PROFILE 0 // Set to 1 to profile the functions below.
158
159 #if DO_ASAN_MAPPING_PROFILE
160 # define PROFILE_ASAN_MAPPING() AsanMappingProfile[__LINE__]++;
161 #else
162 # define PROFILE_ASAN_MAPPING()
163 #endif
164
165 // If 1, all shadow boundaries are constants.
166 // Don't set to 1 other than for testing.
167 #define ASAN_FIXED_MAPPING 0
168
169 namespace __asan {
170
171 extern uptr AsanMappingProfile[];
172
173 #if ASAN_FIXED_MAPPING
174 // Fixed mapping for 64-bit Linux. Mostly used for performance comparison
175 // with non-fixed mapping. As of r175253 (Feb 2013) the performance
176 // difference between fixed and non-fixed mapping is below the noise level.
177 static uptr kHighMemEnd = 0x7fffffffffffULL;
178 static uptr kMidMemBeg = 0x3000000000ULL;
179 static uptr kMidMemEnd = 0x4fffffffffULL;
180 #else
181 extern uptr kHighMemEnd, kMidMemBeg, kMidMemEnd; // Initialized in __asan_init.
182 #endif
183
AddrIsInLowMem(uptr a)184 static inline bool AddrIsInLowMem(uptr a) {
185 PROFILE_ASAN_MAPPING();
186 return a < kLowMemEnd;
187 }
188
AddrIsInLowShadow(uptr a)189 static inline bool AddrIsInLowShadow(uptr a) {
190 PROFILE_ASAN_MAPPING();
191 return a >= kLowShadowBeg && a <= kLowShadowEnd;
192 }
193
AddrIsInHighMem(uptr a)194 static inline bool AddrIsInHighMem(uptr a) {
195 PROFILE_ASAN_MAPPING();
196 return a >= kHighMemBeg && a <= kHighMemEnd;
197 }
198
AddrIsInMidMem(uptr a)199 static inline bool AddrIsInMidMem(uptr a) {
200 PROFILE_ASAN_MAPPING();
201 return kMidMemBeg && a >= kMidMemBeg && a <= kMidMemEnd;
202 }
203
AddrIsInMem(uptr a)204 static inline bool AddrIsInMem(uptr a) {
205 PROFILE_ASAN_MAPPING();
206 return AddrIsInLowMem(a) || AddrIsInMidMem(a) || AddrIsInHighMem(a);
207 }
208
MemToShadow(uptr p)209 static inline uptr MemToShadow(uptr p) {
210 PROFILE_ASAN_MAPPING();
211 CHECK(AddrIsInMem(p));
212 return MEM_TO_SHADOW(p);
213 }
214
AddrIsInHighShadow(uptr a)215 static inline bool AddrIsInHighShadow(uptr a) {
216 PROFILE_ASAN_MAPPING();
217 return a >= kHighShadowBeg && a <= kHighMemEnd;
218 }
219
AddrIsInMidShadow(uptr a)220 static inline bool AddrIsInMidShadow(uptr a) {
221 PROFILE_ASAN_MAPPING();
222 return kMidMemBeg && a >= kMidShadowBeg && a <= kMidMemEnd;
223 }
224
AddrIsInShadow(uptr a)225 static inline bool AddrIsInShadow(uptr a) {
226 PROFILE_ASAN_MAPPING();
227 return AddrIsInLowShadow(a) || AddrIsInMidShadow(a) || AddrIsInHighShadow(a);
228 }
229
AddrIsInShadowGap(uptr a)230 static inline bool AddrIsInShadowGap(uptr a) {
231 PROFILE_ASAN_MAPPING();
232 if (kMidMemBeg) {
233 if (a <= kShadowGapEnd)
234 return SHADOW_OFFSET == 0 || a >= kShadowGapBeg;
235 return (a >= kShadowGap2Beg && a <= kShadowGap2End) ||
236 (a >= kShadowGap3Beg && a <= kShadowGap3End);
237 }
238 // In zero-based shadow mode we treat addresses near zero as addresses
239 // in shadow gap as well.
240 if (SHADOW_OFFSET == 0)
241 return a <= kShadowGapEnd;
242 return a >= kShadowGapBeg && a <= kShadowGapEnd;
243 }
244
AddrIsAlignedByGranularity(uptr a)245 static inline bool AddrIsAlignedByGranularity(uptr a) {
246 PROFILE_ASAN_MAPPING();
247 return (a & (SHADOW_GRANULARITY - 1)) == 0;
248 }
249
AddressIsPoisoned(uptr a)250 static inline bool AddressIsPoisoned(uptr a) {
251 PROFILE_ASAN_MAPPING();
252 const uptr kAccessSize = 1;
253 u8 *shadow_address = (u8*)MEM_TO_SHADOW(a);
254 s8 shadow_value = *shadow_address;
255 if (shadow_value) {
256 u8 last_accessed_byte = (a & (SHADOW_GRANULARITY - 1))
257 + kAccessSize - 1;
258 return (last_accessed_byte >= shadow_value);
259 }
260 return false;
261 }
262
263 // Must be after all calls to PROFILE_ASAN_MAPPING().
264 static const uptr kAsanMappingProfileSize = __LINE__;
265
266 } // namespace __asan
267
268 #endif // ASAN_MAPPING_H
269