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
83static const u64 kDefaultShadowScale = 3;
84static const u64 kDefaultShadowOffset32 = 1ULL << 29;  // 0x20000000
85static const u64 kIosShadowOffset32 = 1ULL << 30;  // 0x40000000
86static const u64 kDefaultShadowOffset64 = 1ULL << 44;
87static const u64 kDefaultShort64bitShadowOffset = 0x7FFF8000;  // < 2G.
88static const u64 kAArch64_ShadowOffset64 = 1ULL << 36;
89static const u64 kMIPS32_ShadowOffset32 = 0x0aaa8000;
90static const u64 kPPC64_ShadowOffset64 = 1ULL << 41;
91static const u64 kFreeBSD_ShadowOffset32 = 1ULL << 30;  // 0x40000000
92static 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
169namespace __asan {
170
171extern 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.
177static uptr kHighMemEnd = 0x7fffffffffffULL;
178static uptr kMidMemBeg =    0x3000000000ULL;
179static uptr kMidMemEnd =    0x4fffffffffULL;
180#else
181extern uptr kHighMemEnd, kMidMemBeg, kMidMemEnd;  // Initialized in __asan_init.
182#endif
183
184static inline bool AddrIsInLowMem(uptr a) {
185  PROFILE_ASAN_MAPPING();
186  return a < kLowMemEnd;
187}
188
189static inline bool AddrIsInLowShadow(uptr a) {
190  PROFILE_ASAN_MAPPING();
191  return a >= kLowShadowBeg && a <= kLowShadowEnd;
192}
193
194static inline bool AddrIsInHighMem(uptr a) {
195  PROFILE_ASAN_MAPPING();
196  return a >= kHighMemBeg && a <= kHighMemEnd;
197}
198
199static inline bool AddrIsInMidMem(uptr a) {
200  PROFILE_ASAN_MAPPING();
201  return kMidMemBeg && a >= kMidMemBeg && a <= kMidMemEnd;
202}
203
204static inline bool AddrIsInMem(uptr a) {
205  PROFILE_ASAN_MAPPING();
206  return AddrIsInLowMem(a) || AddrIsInMidMem(a) || AddrIsInHighMem(a);
207}
208
209static inline uptr MemToShadow(uptr p) {
210  PROFILE_ASAN_MAPPING();
211  CHECK(AddrIsInMem(p));
212  return MEM_TO_SHADOW(p);
213}
214
215static inline bool AddrIsInHighShadow(uptr a) {
216  PROFILE_ASAN_MAPPING();
217  return a >= kHighShadowBeg && a <= kHighMemEnd;
218}
219
220static inline bool AddrIsInMidShadow(uptr a) {
221  PROFILE_ASAN_MAPPING();
222  return kMidMemBeg && a >= kMidShadowBeg && a <= kMidMemEnd;
223}
224
225static inline bool AddrIsInShadow(uptr a) {
226  PROFILE_ASAN_MAPPING();
227  return AddrIsInLowShadow(a) || AddrIsInMidShadow(a) || AddrIsInHighShadow(a);
228}
229
230static 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
245static inline bool AddrIsAlignedByGranularity(uptr a) {
246  PROFILE_ASAN_MAPPING();
247  return (a & (SHADOW_GRANULARITY - 1)) == 0;
248}
249
250static 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().
264static const uptr kAsanMappingProfileSize = __LINE__;
265
266}  // namespace __asan
267
268#endif  // ASAN_MAPPING_H
269