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1 //===-- sanitizer_procmaps_common.cc --------------------------------------===//
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 // Information about the process mappings (common parts).
11 //===----------------------------------------------------------------------===//
12 
13 #include "sanitizer_platform.h"
14 
15 #if SANITIZER_FREEBSD || SANITIZER_LINUX
16 
17 #include "sanitizer_common.h"
18 #include "sanitizer_placement_new.h"
19 #include "sanitizer_procmaps.h"
20 
21 namespace __sanitizer {
22 
23 // Linker initialized.
24 ProcSelfMapsBuff MemoryMappingLayout::cached_proc_self_maps_;
25 StaticSpinMutex MemoryMappingLayout::cache_lock_;  // Linker initialized.
26 
TranslateDigit(char c)27 static int TranslateDigit(char c) {
28   if (c >= '0' && c <= '9')
29     return c - '0';
30   if (c >= 'a' && c <= 'f')
31     return c - 'a' + 10;
32   if (c >= 'A' && c <= 'F')
33     return c - 'A' + 10;
34   return -1;
35 }
36 
37 // Parse a number and promote 'p' up to the first non-digit character.
ParseNumber(const char ** p,int base)38 static uptr ParseNumber(const char **p, int base) {
39   uptr n = 0;
40   int d;
41   CHECK(base >= 2 && base <= 16);
42   while ((d = TranslateDigit(**p)) >= 0 && d < base) {
43     n = n * base + d;
44     (*p)++;
45   }
46   return n;
47 }
48 
IsDecimal(char c)49 bool IsDecimal(char c) {
50   int d = TranslateDigit(c);
51   return d >= 0 && d < 10;
52 }
53 
ParseDecimal(const char ** p)54 uptr ParseDecimal(const char **p) {
55   return ParseNumber(p, 10);
56 }
57 
IsHex(char c)58 bool IsHex(char c) {
59   int d = TranslateDigit(c);
60   return d >= 0 && d < 16;
61 }
62 
ParseHex(const char ** p)63 uptr ParseHex(const char **p) {
64   return ParseNumber(p, 16);
65 }
66 
MemoryMappingLayout(bool cache_enabled)67 MemoryMappingLayout::MemoryMappingLayout(bool cache_enabled) {
68   ReadProcMaps(&proc_self_maps_);
69   if (cache_enabled) {
70     if (proc_self_maps_.mmaped_size == 0) {
71       LoadFromCache();
72       CHECK_GT(proc_self_maps_.len, 0);
73     }
74   } else {
75     CHECK_GT(proc_self_maps_.mmaped_size, 0);
76   }
77   Reset();
78   // FIXME: in the future we may want to cache the mappings on demand only.
79   if (cache_enabled)
80     CacheMemoryMappings();
81 }
82 
~MemoryMappingLayout()83 MemoryMappingLayout::~MemoryMappingLayout() {
84   // Only unmap the buffer if it is different from the cached one. Otherwise
85   // it will be unmapped when the cache is refreshed.
86   if (proc_self_maps_.data != cached_proc_self_maps_.data) {
87     UnmapOrDie(proc_self_maps_.data, proc_self_maps_.mmaped_size);
88   }
89 }
90 
Reset()91 void MemoryMappingLayout::Reset() {
92   current_ = proc_self_maps_.data;
93 }
94 
95 // static
CacheMemoryMappings()96 void MemoryMappingLayout::CacheMemoryMappings() {
97   SpinMutexLock l(&cache_lock_);
98   // Don't invalidate the cache if the mappings are unavailable.
99   ProcSelfMapsBuff old_proc_self_maps;
100   old_proc_self_maps = cached_proc_self_maps_;
101   ReadProcMaps(&cached_proc_self_maps_);
102   if (cached_proc_self_maps_.mmaped_size == 0) {
103     cached_proc_self_maps_ = old_proc_self_maps;
104   } else {
105     if (old_proc_self_maps.mmaped_size) {
106       UnmapOrDie(old_proc_self_maps.data,
107                  old_proc_self_maps.mmaped_size);
108     }
109   }
110 }
111 
LoadFromCache()112 void MemoryMappingLayout::LoadFromCache() {
113   SpinMutexLock l(&cache_lock_);
114   if (cached_proc_self_maps_.data) {
115     proc_self_maps_ = cached_proc_self_maps_;
116   }
117 }
118 
DumpListOfModules(InternalMmapVector<LoadedModule> * modules)119 void MemoryMappingLayout::DumpListOfModules(
120     InternalMmapVector<LoadedModule> *modules) {
121   Reset();
122   uptr cur_beg, cur_end, cur_offset, prot;
123   InternalScopedString module_name(kMaxPathLength);
124   for (uptr i = 0; Next(&cur_beg, &cur_end, &cur_offset, module_name.data(),
125                         module_name.size(), &prot);
126        i++) {
127     const char *cur_name = module_name.data();
128     if (cur_name[0] == '\0')
129       continue;
130     // Don't subtract 'cur_beg' from the first entry:
131     // * If a binary is compiled w/o -pie, then the first entry in
132     //   process maps is likely the binary itself (all dynamic libs
133     //   are mapped higher in address space). For such a binary,
134     //   instruction offset in binary coincides with the actual
135     //   instruction address in virtual memory (as code section
136     //   is mapped to a fixed memory range).
137     // * If a binary is compiled with -pie, all the modules are
138     //   mapped high at address space (in particular, higher than
139     //   shadow memory of the tool), so the module can't be the
140     //   first entry.
141     uptr base_address = (i ? cur_beg : 0) - cur_offset;
142     LoadedModule cur_module;
143     cur_module.set(cur_name, base_address);
144     cur_module.addAddressRange(cur_beg, cur_end, prot & kProtectionExecute);
145     modules->push_back(cur_module);
146   }
147 }
148 
GetMemoryProfile(fill_profile_f cb,uptr * stats,uptr stats_size)149 void GetMemoryProfile(fill_profile_f cb, uptr *stats, uptr stats_size) {
150   char *smaps = nullptr;
151   uptr smaps_cap = 0;
152   uptr smaps_len = 0;
153   if (!ReadFileToBuffer("/proc/self/smaps", &smaps, &smaps_cap, &smaps_len))
154     return;
155   uptr start = 0;
156   bool file = false;
157   const char *pos = smaps;
158   while (pos < smaps + smaps_len) {
159     if (IsHex(pos[0])) {
160       start = ParseHex(&pos);
161       for (; *pos != '/' && *pos > '\n'; pos++) {}
162       file = *pos == '/';
163     } else if (internal_strncmp(pos, "Rss:", 4) == 0) {
164       while (!IsDecimal(*pos)) pos++;
165       uptr rss = ParseDecimal(&pos) * 1024;
166       cb(start, rss, file, stats, stats_size);
167     }
168     while (*pos++ != '\n') {}
169   }
170   UnmapOrDie(smaps, smaps_cap);
171 }
172 
173 } // namespace __sanitizer
174 
175 #endif // SANITIZER_FREEBSD || SANITIZER_LINUX
176