asan_mapping.h revision 280031 
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/MIPS32 mapping:
63// || `[0x2aaa0000, 0xffffffff]` || HighMem    ||
64// || `[0x0fff4000, 0x2aa9ffff]` || HighShadow ||
65// || `[0x0bff4000, 0x0fff3fff]` || ShadowGap  ||
66// || `[0x0aaa0000, 0x0bff3fff]` || LowShadow  ||
67// || `[0x00000000, 0x0aa9ffff]` || LowMem     ||
68//
69// Default Linux/MIPS64 mapping:
70// || `[0x4000000000, 0xffffffffff]` || HighMem    ||
71// || `[0x2800000000, 0x3fffffffff]` || HighShadow ||
72// || `[0x2400000000, 0x27ffffffff]` || ShadowGap  ||
73// || `[0x2000000000, 0x23ffffffff]` || LowShadow  ||
74// || `[0x0000000000, 0x1fffffffff]` || LowMem     ||
75//
76// Shadow mapping on FreeBSD/x86-64 with SHADOW_OFFSET == 0x400000000000:
77// || `[0x500000000000, 0x7fffffffffff]` || HighMem    ||
78// || `[0x4a0000000000, 0x4fffffffffff]` || HighShadow ||
79// || `[0x480000000000, 0x49ffffffffff]` || ShadowGap  ||
80// || `[0x400000000000, 0x47ffffffffff]` || LowShadow  ||
81// || `[0x000000000000, 0x3fffffffffff]` || LowMem     ||
82//
83// Shadow mapping on FreeBSD/i386 with SHADOW_OFFSET == 0x40000000:
84// || `[0x60000000, 0xffffffff]` || HighMem    ||
85// || `[0x4c000000, 0x5fffffff]` || HighShadow ||
86// || `[0x48000000, 0x4bffffff]` || ShadowGap  ||
87// || `[0x40000000, 0x47ffffff]` || LowShadow  ||
88// || `[0x00000000, 0x3fffffff]` || LowMem     ||
89//
90// Default Windows/i386 mapping:
91// (the exact location of HighShadow/HighMem may vary depending
92//  on WoW64, /LARGEADDRESSAWARE, etc).
93// || `[0x50000000, 0xffffffff]` || HighMem    ||
94// || `[0x3a000000, 0x4fffffff]` || HighShadow ||
95// || `[0x36000000, 0x39ffffff]` || ShadowGap  ||
96// || `[0x30000000, 0x35ffffff]` || LowShadow  ||
97// || `[0x00000000, 0x2fffffff]` || LowMem     ||
98
99static const u64 kDefaultShadowScale = 3;
100static const u64 kDefaultShadowOffset32 = 1ULL << 29;  // 0x20000000
101static const u64 kIosShadowOffset32 = 1ULL << 30;  // 0x40000000
102static const u64 kDefaultShadowOffset64 = 1ULL << 44;
103static const u64 kDefaultShort64bitShadowOffset = 0x7FFF8000;  // < 2G.
104static const u64 kAArch64_ShadowOffset64 = 1ULL << 36;
105static const u64 kMIPS32_ShadowOffset32 = 0x0aaa0000;
106static const u64 kMIPS64_ShadowOffset64 = 1ULL << 37;
107static const u64 kPPC64_ShadowOffset64 = 1ULL << 41;
108static const u64 kFreeBSD_ShadowOffset32 = 1ULL << 30;  // 0x40000000
109static const u64 kFreeBSD_ShadowOffset64 = 1ULL << 46;  // 0x400000000000
110static const u64 kWindowsShadowOffset32 = 3ULL << 28;  // 0x30000000
111
112#define SHADOW_SCALE kDefaultShadowScale
113#if SANITIZER_ANDROID
114# define SHADOW_OFFSET (0)
115#else
116# if SANITIZER_WORDSIZE == 32
117#  if defined(__mips__)
118#    define SHADOW_OFFSET kMIPS32_ShadowOffset32
119#  elif SANITIZER_FREEBSD
120#    define SHADOW_OFFSET kFreeBSD_ShadowOffset32
121#  elif SANITIZER_IOS
122#    define SHADOW_OFFSET kIosShadowOffset32
123#  elif SANITIZER_WINDOWS
124#    define SHADOW_OFFSET kWindowsShadowOffset32
125#  else
126#    define SHADOW_OFFSET kDefaultShadowOffset32
127#  endif
128# else
129#  if defined(__aarch64__)
130#    define SHADOW_OFFSET kAArch64_ShadowOffset64
131#  elif defined(__powerpc64__)
132#    define SHADOW_OFFSET kPPC64_ShadowOffset64
133#  elif SANITIZER_FREEBSD
134#    define SHADOW_OFFSET kFreeBSD_ShadowOffset64
135#  elif SANITIZER_MAC
136#   define SHADOW_OFFSET kDefaultShadowOffset64
137#  elif defined(__mips64)
138#   define SHADOW_OFFSET kMIPS64_ShadowOffset64
139#  else
140#   define SHADOW_OFFSET kDefaultShort64bitShadowOffset
141#  endif
142# endif
143#endif
144
145#define SHADOW_GRANULARITY (1ULL << SHADOW_SCALE)
146#define MEM_TO_SHADOW(mem) (((mem) >> SHADOW_SCALE) + (SHADOW_OFFSET))
147#define SHADOW_TO_MEM(shadow) (((shadow) - SHADOW_OFFSET) << SHADOW_SCALE)
148
149#define kLowMemBeg      0
150#define kLowMemEnd      (SHADOW_OFFSET ? SHADOW_OFFSET - 1 : 0)
151
152#define kLowShadowBeg   SHADOW_OFFSET
153#define kLowShadowEnd   MEM_TO_SHADOW(kLowMemEnd)
154
155#define kHighMemBeg     (MEM_TO_SHADOW(kHighMemEnd) + 1)
156
157#define kHighShadowBeg  MEM_TO_SHADOW(kHighMemBeg)
158#define kHighShadowEnd  MEM_TO_SHADOW(kHighMemEnd)
159
160# define kMidShadowBeg MEM_TO_SHADOW(kMidMemBeg)
161# define kMidShadowEnd MEM_TO_SHADOW(kMidMemEnd)
162
163// With the zero shadow base we can not actually map pages starting from 0.
164// This constant is somewhat arbitrary.
165#define kZeroBaseShadowStart (1 << 18)
166
167#define kShadowGapBeg   (kLowShadowEnd ? kLowShadowEnd + 1 \
168                                       : kZeroBaseShadowStart)
169#define kShadowGapEnd   ((kMidMemBeg ? kMidShadowBeg : kHighShadowBeg) - 1)
170
171#define kShadowGap2Beg (kMidMemBeg ? kMidShadowEnd + 1 : 0)
172#define kShadowGap2End (kMidMemBeg ? kMidMemBeg - 1 : 0)
173
174#define kShadowGap3Beg (kMidMemBeg ? kMidMemEnd + 1 : 0)
175#define kShadowGap3End (kMidMemBeg ? kHighShadowBeg - 1 : 0)
176
177#define DO_ASAN_MAPPING_PROFILE 0  // Set to 1 to profile the functions below.
178
179#if DO_ASAN_MAPPING_PROFILE
180# define PROFILE_ASAN_MAPPING() AsanMappingProfile[__LINE__]++;
181#else
182# define PROFILE_ASAN_MAPPING()
183#endif
184
185// If 1, all shadow boundaries are constants.
186// Don't set to 1 other than for testing.
187#define ASAN_FIXED_MAPPING 0
188
189namespace __asan {
190
191extern uptr AsanMappingProfile[];
192
193#if ASAN_FIXED_MAPPING
194// Fixed mapping for 64-bit Linux. Mostly used for performance comparison
195// with non-fixed mapping. As of r175253 (Feb 2013) the performance
196// difference between fixed and non-fixed mapping is below the noise level.
197static uptr kHighMemEnd = 0x7fffffffffffULL;
198static uptr kMidMemBeg =    0x3000000000ULL;
199static uptr kMidMemEnd =    0x4fffffffffULL;
200#else
201extern uptr kHighMemEnd, kMidMemBeg, kMidMemEnd;  // Initialized in __asan_init.
202#endif
203
204static inline bool AddrIsInLowMem(uptr a) {
205  PROFILE_ASAN_MAPPING();
206  return a < kLowMemEnd;
207}
208
209static inline bool AddrIsInLowShadow(uptr a) {
210  PROFILE_ASAN_MAPPING();
211  return a >= kLowShadowBeg && a <= kLowShadowEnd;
212}
213
214static inline bool AddrIsInHighMem(uptr a) {
215  PROFILE_ASAN_MAPPING();
216  return a >= kHighMemBeg && a <= kHighMemEnd;
217}
218
219static inline bool AddrIsInMidMem(uptr a) {
220  PROFILE_ASAN_MAPPING();
221  return kMidMemBeg && a >= kMidMemBeg && a <= kMidMemEnd;
222}
223
224static inline bool AddrIsInMem(uptr a) {
225  PROFILE_ASAN_MAPPING();
226  return AddrIsInLowMem(a) || AddrIsInMidMem(a) || AddrIsInHighMem(a);
227}
228
229static inline uptr MemToShadow(uptr p) {
230  PROFILE_ASAN_MAPPING();
231  CHECK(AddrIsInMem(p));
232  return MEM_TO_SHADOW(p);
233}
234
235static inline bool AddrIsInHighShadow(uptr a) {
236  PROFILE_ASAN_MAPPING();
237  return a >= kHighShadowBeg && a <= kHighMemEnd;
238}
239
240static inline bool AddrIsInMidShadow(uptr a) {
241  PROFILE_ASAN_MAPPING();
242  return kMidMemBeg && a >= kMidShadowBeg && a <= kMidMemEnd;
243}
244
245static inline bool AddrIsInShadow(uptr a) {
246  PROFILE_ASAN_MAPPING();
247  return AddrIsInLowShadow(a) || AddrIsInMidShadow(a) || AddrIsInHighShadow(a);
248}
249
250static inline bool AddrIsInShadowGap(uptr a) {
251  PROFILE_ASAN_MAPPING();
252  if (kMidMemBeg) {
253    if (a <= kShadowGapEnd)
254      return SHADOW_OFFSET == 0 || a >= kShadowGapBeg;
255    return (a >= kShadowGap2Beg && a <= kShadowGap2End) ||
256           (a >= kShadowGap3Beg && a <= kShadowGap3End);
257  }
258  // In zero-based shadow mode we treat addresses near zero as addresses
259  // in shadow gap as well.
260  if (SHADOW_OFFSET == 0)
261    return a <= kShadowGapEnd;
262  return a >= kShadowGapBeg && a <= kShadowGapEnd;
263}
264
265static inline bool AddrIsAlignedByGranularity(uptr a) {
266  PROFILE_ASAN_MAPPING();
267  return (a & (SHADOW_GRANULARITY - 1)) == 0;
268}
269
270static inline bool AddressIsPoisoned(uptr a) {
271  PROFILE_ASAN_MAPPING();
272  const uptr kAccessSize = 1;
273  u8 *shadow_address = (u8*)MEM_TO_SHADOW(a);
274  s8 shadow_value = *shadow_address;
275  if (shadow_value) {
276    u8 last_accessed_byte = (a & (SHADOW_GRANULARITY - 1))
277                                 + kAccessSize - 1;
278    return (last_accessed_byte >= shadow_value);
279  }
280  return false;
281}
282
283// Must be after all calls to PROFILE_ASAN_MAPPING().
284static const uptr kAsanMappingProfileSize = __LINE__;
285
286}  // namespace __asan
287
288#endif  // ASAN_MAPPING_H
289