asan_mapping.h revision 1.3 
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 on x86_64 machine:
45// || `[0x40000000, 0xffffffff]` || HighMem    ||
46// || `[0x28000000, 0x3fffffff]` || HighShadow ||
47// || `[0x24000000, 0x27ffffff]` || ShadowGap  ||
48// || `[0x20000000, 0x23ffffff]` || LowShadow  ||
49// || `[0x00000000, 0x1fffffff]` || LowMem     ||
50//
51// Default Linux/i386 mapping on i386 machine
52// (addresses starting with 0xc0000000 are reserved
53// for kernel and thus not sanitized):
54// || `[0x38000000, 0xbfffffff]` || HighMem    ||
55// || `[0x27000000, 0x37ffffff]` || HighShadow ||
56// || `[0x24000000, 0x26ffffff]` || ShadowGap  ||
57// || `[0x20000000, 0x23ffffff]` || LowShadow  ||
58// || `[0x00000000, 0x1fffffff]` || LowMem     ||
59//
60// Default Linux/MIPS mapping:
61// || `[0x2aaa0000, 0xffffffff]` || HighMem    ||
62// || `[0x0fff4000, 0x2aa9ffff]` || HighShadow ||
63// || `[0x0bff4000, 0x0fff3fff]` || ShadowGap  ||
64// || `[0x0aaa0000, 0x0bff3fff]` || LowShadow  ||
65// || `[0x00000000, 0x0aa9ffff]` || LowMem     ||
66//
67// Shadow mapping on FreeBSD/x86-64 with SHADOW_OFFSET == 0x400000000000:
68// || `[0x500000000000, 0x7fffffffffff]` || HighMem    ||
69// || `[0x4a0000000000, 0x4fffffffffff]` || HighShadow ||
70// || `[0x480000000000, 0x49ffffffffff]` || ShadowGap  ||
71// || `[0x400000000000, 0x47ffffffffff]` || LowShadow  ||
72// || `[0x000000000000, 0x3fffffffffff]` || LowMem     ||
73//
74// Shadow mapping on FreeBSD/i386 with SHADOW_OFFSET == 0x40000000:
75// || `[0x60000000, 0xffffffff]` || HighMem    ||
76// || `[0x4c000000, 0x5fffffff]` || HighShadow ||
77// || `[0x48000000, 0x4bffffff]` || ShadowGap  ||
78// || `[0x40000000, 0x47ffffff]` || LowShadow  ||
79// || `[0x00000000, 0x3fffffff]` || LowMem     ||
80
81static const u64 kDefaultShadowScale = 3;
82static const u64 kDefaultShadowOffset32 = 1ULL << 29;  // 0x20000000
83static const u64 kIosShadowOffset32 = 1ULL << 30;  // 0x40000000
84static const u64 kDefaultShadowOffset64 = 1ULL << 44;
85static const u64 kDefaultShort64bitShadowOffset = 0x7FFF8000;  // < 2G.
86static const u64 kAArch64_ShadowOffset64 = 1ULL << 36;
87static const u64 kMIPS32_ShadowOffset32 = 0x0aaa0000;
88static const u64 kMIPS64_ShadowOffset64 = 1ULL << 36;
89static const u64 kPPC64_ShadowOffset64 = 1ULL << 41;
90static const u64 kFreeBSD_ShadowOffset32 = 1ULL << 30;  // 0x40000000
91static const u64 kFreeBSD_ShadowOffset64 = 1ULL << 46;  // 0x400000000000
92
93#define SHADOW_SCALE kDefaultShadowScale
94#if SANITIZER_ANDROID
95# define SHADOW_OFFSET (0)
96#else
97# if SANITIZER_WORDSIZE == 32
98#  if defined(__mips__)
99#    define SHADOW_OFFSET kMIPS32_ShadowOffset32
100#  elif SANITIZER_FREEBSD
101#    define SHADOW_OFFSET kFreeBSD_ShadowOffset32
102#  else
103#    if SANITIZER_IOS
104#      define SHADOW_OFFSET kIosShadowOffset32
105#    else
106#      define SHADOW_OFFSET kDefaultShadowOffset32
107#    endif
108#  endif
109# else
110#  if defined(__aarch64__)
111#    define SHADOW_OFFSET kAArch64_ShadowOffset64
112#  elif defined(__powerpc64__)
113#    define SHADOW_OFFSET kPPC64_ShadowOffset64
114#  elif SANITIZER_FREEBSD
115#    define SHADOW_OFFSET kFreeBSD_ShadowOffset64
116#  elif SANITIZER_MAC
117#   define SHADOW_OFFSET kDefaultShadowOffset64
118#  elif defined(__mips64)
119#   define SHADOW_OFFSET kMIPS64_ShadowOffset64
120#  else
121#   define SHADOW_OFFSET kDefaultShort64bitShadowOffset
122#  endif
123# endif
124#endif
125
126#define SHADOW_GRANULARITY (1ULL << SHADOW_SCALE)
127#define MEM_TO_SHADOW(mem) (((mem) >> SHADOW_SCALE) + (SHADOW_OFFSET))
128#define SHADOW_TO_MEM(shadow) (((shadow) - SHADOW_OFFSET) << SHADOW_SCALE)
129
130#define kLowMemBeg      0
131#define kLowMemEnd      (SHADOW_OFFSET ? SHADOW_OFFSET - 1 : 0)
132
133#define kLowShadowBeg   SHADOW_OFFSET
134#define kLowShadowEnd   MEM_TO_SHADOW(kLowMemEnd)
135
136#define kHighMemBeg     (MEM_TO_SHADOW(kHighMemEnd) + 1)
137
138#define kHighShadowBeg  MEM_TO_SHADOW(kHighMemBeg)
139#define kHighShadowEnd  MEM_TO_SHADOW(kHighMemEnd)
140
141# define kMidShadowBeg MEM_TO_SHADOW(kMidMemBeg)
142# define kMidShadowEnd MEM_TO_SHADOW(kMidMemEnd)
143
144// With the zero shadow base we can not actually map pages starting from 0.
145// This constant is somewhat arbitrary.
146#define kZeroBaseShadowStart (1 << 18)
147
148#define kShadowGapBeg   (kLowShadowEnd ? kLowShadowEnd + 1 \
149                                       : kZeroBaseShadowStart)
150#define kShadowGapEnd   ((kMidMemBeg ? kMidShadowBeg : kHighShadowBeg) - 1)
151
152#define kShadowGap2Beg (kMidMemBeg ? kMidShadowEnd + 1 : 0)
153#define kShadowGap2End (kMidMemBeg ? kMidMemBeg - 1 : 0)
154
155#define kShadowGap3Beg (kMidMemBeg ? kMidMemEnd + 1 : 0)
156#define kShadowGap3End (kMidMemBeg ? kHighShadowBeg - 1 : 0)
157
158#define DO_ASAN_MAPPING_PROFILE 0  // Set to 1 to profile the functions below.
159
160#if DO_ASAN_MAPPING_PROFILE
161# define PROFILE_ASAN_MAPPING() AsanMappingProfile[__LINE__]++;
162#else
163# define PROFILE_ASAN_MAPPING()
164#endif
165
166// If 1, all shadow boundaries are constants.
167// Don't set to 1 other than for testing.
168#define ASAN_FIXED_MAPPING 0
169
170namespace __asan {
171
172extern uptr AsanMappingProfile[];
173
174#if ASAN_FIXED_MAPPING
175// Fixed mapping for 64-bit Linux. Mostly used for performance comparison
176// with non-fixed mapping. As of r175253 (Feb 2013) the performance
177// difference between fixed and non-fixed mapping is below the noise level.
178static uptr kHighMemEnd = 0x7fffffffffffULL;
179static uptr kMidMemBeg =    0x3000000000ULL;
180static uptr kMidMemEnd =    0x4fffffffffULL;
181#else
182extern uptr kHighMemEnd, kMidMemBeg, kMidMemEnd;  // Initialized in __asan_init.
183#endif
184
185static inline bool AddrIsInLowMem(uptr a) {
186  PROFILE_ASAN_MAPPING();
187  return a < kLowMemEnd;
188}
189
190static inline bool AddrIsInLowShadow(uptr a) {
191  PROFILE_ASAN_MAPPING();
192  return a >= kLowShadowBeg && a <= kLowShadowEnd;
193}
194
195static inline bool AddrIsInHighMem(uptr a) {
196  PROFILE_ASAN_MAPPING();
197  return a >= kHighMemBeg && a <= kHighMemEnd;
198}
199
200static inline bool AddrIsInMidMem(uptr a) {
201  PROFILE_ASAN_MAPPING();
202  return kMidMemBeg && a >= kMidMemBeg && a <= kMidMemEnd;
203}
204
205static inline bool AddrIsInMem(uptr a) {
206  PROFILE_ASAN_MAPPING();
207  return AddrIsInLowMem(a) || AddrIsInMidMem(a) || AddrIsInHighMem(a);
208}
209
210static inline uptr MemToShadow(uptr p) {
211  PROFILE_ASAN_MAPPING();
212  CHECK(AddrIsInMem(p));
213  return MEM_TO_SHADOW(p);
214}
215
216static inline bool AddrIsInHighShadow(uptr a) {
217  PROFILE_ASAN_MAPPING();
218  return a >= kHighShadowBeg && a <= kHighMemEnd;
219}
220
221static inline bool AddrIsInMidShadow(uptr a) {
222  PROFILE_ASAN_MAPPING();
223  return kMidMemBeg && a >= kMidShadowBeg && a <= kMidMemEnd;
224}
225
226static inline bool AddrIsInShadow(uptr a) {
227  PROFILE_ASAN_MAPPING();
228  return AddrIsInLowShadow(a) || AddrIsInMidShadow(a) || AddrIsInHighShadow(a);
229}
230
231static inline bool AddrIsInShadowGap(uptr a) {
232  PROFILE_ASAN_MAPPING();
233  if (kMidMemBeg) {
234    if (a <= kShadowGapEnd)
235      return SHADOW_OFFSET == 0 || a >= kShadowGapBeg;
236    return (a >= kShadowGap2Beg && a <= kShadowGap2End) ||
237           (a >= kShadowGap3Beg && a <= kShadowGap3End);
238  }
239  // In zero-based shadow mode we treat addresses near zero as addresses
240  // in shadow gap as well.
241  if (SHADOW_OFFSET == 0)
242    return a <= kShadowGapEnd;
243  return a >= kShadowGapBeg && a <= kShadowGapEnd;
244}
245
246static inline bool AddrIsAlignedByGranularity(uptr a) {
247  PROFILE_ASAN_MAPPING();
248  return (a & (SHADOW_GRANULARITY - 1)) == 0;
249}
250
251static inline bool AddressIsPoisoned(uptr a) {
252  PROFILE_ASAN_MAPPING();
253  const uptr kAccessSize = 1;
254  u8 *shadow_address = (u8*)MEM_TO_SHADOW(a);
255  s8 shadow_value = *shadow_address;
256  if (shadow_value) {
257    u8 last_accessed_byte = (a & (SHADOW_GRANULARITY - 1))
258                                 + kAccessSize - 1;
259    return (last_accessed_byte >= shadow_value);
260  }
261  return false;
262}
263
264// Must be after all calls to PROFILE_ASAN_MAPPING().
265static const uptr kAsanMappingProfileSize = __LINE__;
266
267}  // namespace __asan
268
269#endif  // ASAN_MAPPING_H
270