asan_mapping.h revision 13577fed9ac2ebe5e4800b8f83e3a80832907de2 
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
54extern SANITIZER_INTERFACE_ATTRIBUTE uptr __asan_mapping_scale;
55extern 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
124namespace __asan {
125
126extern 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.
132static uptr kHighMemEnd = 0x7fffffffffffULL;
133static uptr kMidMemBeg =    0x3000000000ULL;
134static uptr kMidMemEnd =    0x4fffffffffULL;
135#else
136SANITIZER_INTERFACE_ATTRIBUTE
137extern uptr kHighMemEnd, kMidMemBeg, kMidMemEnd;  // Initialized in __asan_init.
138#endif
139
140static inline bool AddrIsInLowMem(uptr a) {
141  PROFILE_ASAN_MAPPING();
142  return a < kLowMemEnd;
143}
144
145static inline bool AddrIsInLowShadow(uptr a) {
146  PROFILE_ASAN_MAPPING();
147  return a >= kLowShadowBeg && a <= kLowShadowEnd;
148}
149
150static inline bool AddrIsInHighMem(uptr a) {
151  PROFILE_ASAN_MAPPING();
152  return a >= kHighMemBeg && a <= kHighMemEnd;
153}
154
155static inline bool AddrIsInMidMem(uptr a) {
156  PROFILE_ASAN_MAPPING();
157  return kMidMemBeg && a >= kMidMemBeg && a <= kMidMemEnd;
158}
159
160static inline bool AddrIsInMem(uptr a) {
161  PROFILE_ASAN_MAPPING();
162  return AddrIsInLowMem(a) || AddrIsInMidMem(a) || AddrIsInHighMem(a);
163}
164
165static inline uptr MemToShadow(uptr p) {
166  PROFILE_ASAN_MAPPING();
167  CHECK(AddrIsInMem(p));
168  return MEM_TO_SHADOW(p);
169}
170
171static inline bool AddrIsInHighShadow(uptr a) {
172  PROFILE_ASAN_MAPPING();
173  return a >= kHighShadowBeg && a <= kHighMemEnd;
174}
175
176static inline bool AddrIsInMidShadow(uptr a) {
177  PROFILE_ASAN_MAPPING();
178  return kMidMemBeg && a >= kMidShadowBeg && a <= kMidMemEnd;
179}
180
181static inline bool AddrIsInShadow(uptr a) {
182  PROFILE_ASAN_MAPPING();
183  return AddrIsInLowShadow(a) || AddrIsInMidShadow(a) || AddrIsInHighShadow(a);
184}
185
186static 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
201static inline bool AddrIsAlignedByGranularity(uptr a) {
202  PROFILE_ASAN_MAPPING();
203  return (a & (SHADOW_GRANULARITY - 1)) == 0;
204}
205
206static 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().
220static const uptr kAsanMappingProfileSize = __LINE__;
221
222}  // namespace __asan
223
224#endif  // ASAN_MAPPING_H
225