1//===-- sanitizer_procmaps_common.cpp -------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// Information about the process mappings (common parts).
10//===----------------------------------------------------------------------===//
11
12#include "sanitizer_platform.h"
13
14#if SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD || \
15 SANITIZER_SOLARIS
16
17#include "sanitizer_common.h"
18#include "sanitizer_placement_new.h"
19#include "sanitizer_procmaps.h"
20
21namespace __sanitizer {
22
23static ProcSelfMapsBuff cached_proc_self_maps;
24static StaticSpinMutex cache_lock;
25
26static int TranslateDigit(char c) {
27 if (c >= '0' && c <= '9')
28 return c - '0';
29 if (c >= 'a' && c <= 'f')
30 return c - 'a' + 10;
31 if (c >= 'A' && c <= 'F')
32 return c - 'A' + 10;
33 return -1;
34}
35
36// Parse a number and promote 'p' up to the first non-digit character.
37static uptr ParseNumber(const char **p, int base) {
38 uptr n = 0;
39 int d;
40 CHECK(base >= 2 && base <= 16);
41 while ((d = TranslateDigit(c: **p)) >= 0 && d < base) {
42 n = n * base + d;
43 (*p)++;
44 }
45 return n;
46}
47
48bool IsDecimal(char c) {
49 int d = TranslateDigit(c);
50 return d >= 0 && d < 10;
51}
52
53uptr ParseDecimal(const char **p) {
54 return ParseNumber(p, base: 10);
55}
56
57bool IsHex(char c) {
58 int d = TranslateDigit(c);
59 return d >= 0 && d < 16;
60}
61
62uptr ParseHex(const char **p) {
63 return ParseNumber(p, base: 16);
64}
65
66void MemoryMappedSegment::AddAddressRanges(LoadedModule *module) {
67 // data_ should be unused on this platform
68 CHECK(!data_);
69 module->addAddressRange(beg: start, end, executable: IsExecutable(), writable: IsWritable());
70}
71
72MemoryMappingLayout::MemoryMappingLayout(bool cache_enabled) {
73 // FIXME: in the future we may want to cache the mappings on demand only.
74 if (cache_enabled)
75 CacheMemoryMappings();
76
77 // Read maps after the cache update to capture the maps/unmaps happening in
78 // the process of updating.
79 ReadProcMaps(proc_maps: &data_.proc_self_maps);
80 if (cache_enabled && data_.proc_self_maps.mmaped_size == 0)
81 LoadFromCache();
82
83 Reset();
84}
85
86bool MemoryMappingLayout::Error() const {
87 return data_.current == nullptr;
88}
89
90MemoryMappingLayout::~MemoryMappingLayout() {
91 // Only unmap the buffer if it is different from the cached one. Otherwise
92 // it will be unmapped when the cache is refreshed.
93 if (data_.proc_self_maps.data != cached_proc_self_maps.data)
94 UnmapOrDie(addr: data_.proc_self_maps.data, size: data_.proc_self_maps.mmaped_size);
95}
96
97void MemoryMappingLayout::Reset() {
98 data_.current = data_.proc_self_maps.data;
99}
100
101// static
102void MemoryMappingLayout::CacheMemoryMappings() {
103 ProcSelfMapsBuff new_proc_self_maps;
104 ReadProcMaps(proc_maps: &new_proc_self_maps);
105 // Don't invalidate the cache if the mappings are unavailable.
106 if (new_proc_self_maps.mmaped_size == 0)
107 return;
108 SpinMutexLock l(&cache_lock);
109 if (cached_proc_self_maps.mmaped_size)
110 UnmapOrDie(addr: cached_proc_self_maps.data, size: cached_proc_self_maps.mmaped_size);
111 cached_proc_self_maps = new_proc_self_maps;
112}
113
114void MemoryMappingLayout::LoadFromCache() {
115 SpinMutexLock l(&cache_lock);
116 if (cached_proc_self_maps.data)
117 data_.proc_self_maps = cached_proc_self_maps;
118}
119
120void MemoryMappingLayout::DumpListOfModules(
121 InternalMmapVectorNoCtor<LoadedModule> *modules) {
122 Reset();
123 InternalMmapVector<char> module_name(kMaxPathLength);
124 MemoryMappedSegment segment(module_name.data(), module_name.size());
125 for (uptr i = 0; Next(segment: &segment); i++) {
126 const char *cur_name = segment.filename;
127 if (cur_name[0] == '\0')
128 continue;
129 // Don't subtract 'cur_beg' from the first entry:
130 // * If a binary is compiled w/o -pie, then the first entry in
131 // process maps is likely the binary itself (all dynamic libs
132 // are mapped higher in address space). For such a binary,
133 // instruction offset in binary coincides with the actual
134 // instruction address in virtual memory (as code section
135 // is mapped to a fixed memory range).
136 // * If a binary is compiled with -pie, all the modules are
137 // mapped high at address space (in particular, higher than
138 // shadow memory of the tool), so the module can't be the
139 // first entry.
140 uptr base_address = (i ? segment.start : 0) - segment.offset;
141 LoadedModule cur_module;
142 cur_module.set(module_name: cur_name, base_address);
143 segment.AddAddressRanges(module: &cur_module);
144 modules->push_back(element: cur_module);
145 }
146}
147
148#if SANITIZER_LINUX || SANITIZER_ANDROID || SANITIZER_SOLARIS
149void GetMemoryProfile(fill_profile_f cb, uptr *stats) {
150 char *smaps = nullptr;
151 uptr smaps_cap = 0;
152 uptr smaps_len = 0;
153 if (!ReadFileToBuffer(file_name: "/proc/self/smaps", buff: &smaps, buff_size: &smaps_cap, read_len: &smaps_len))
154 return;
155 ParseUnixMemoryProfile(cb, stats, smaps, smaps_len);
156 UnmapOrDie(addr: smaps, size: smaps_cap);
157}
158
159void ParseUnixMemoryProfile(fill_profile_f cb, uptr *stats, char *smaps,
160 uptr smaps_len) {
161 uptr start = 0;
162 bool file = false;
163 const char *pos = smaps;
164 char *end = smaps + smaps_len;
165 if (smaps_len < 2)
166 return;
167 // The following parsing can crash on almost every line
168 // in the case of malformed/truncated input.
169 // Fixing that is hard b/c e.g. ParseDecimal does not
170 // even accept end of the buffer and assumes well-formed input.
171 // So instead we patch end of the input a bit,
172 // it does not affect well-formed complete inputs.
173 *--end = 0;
174 *--end = '\n';
175 while (pos < end) {
176 if (IsHex(c: pos[0])) {
177 start = ParseHex(p: &pos);
178 for (; *pos != '/' && *pos > '\n'; pos++) {}
179 file = *pos == '/';
180 } else if (internal_strncmp(s1: pos, s2: "Rss:", n: 4) == 0) {
181 while (pos < end && !IsDecimal(c: *pos)) pos++;
182 uptr rss = ParseDecimal(p: &pos) * 1024;
183 cb(start, rss, file, stats);
184 }
185 while (*pos++ != '\n') {}
186 }
187}
188#endif
189
190} // namespace __sanitizer
191
192#endif
193