libsanitizer/sanitizer_common/sanitizer_procmaps_common.cpp

   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
  21 namespace __sanitizer {
  22
  23 static ProcSelfMapsBuff cached_proc_self_maps;
  24 static StaticSpinMutex cache_lock;
  25
  26 static 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.
  37 static uptr ParseNumber(const char **p, int base) {
  38   uptr n = 0;
  39   int d;
  40   CHECK(base >= 2 && base <= 16);
  41   while ((d = TranslateDigit(**p)) >= 0 && d < base) {
  42     n = n * base + d;
  43     (*p)++;
  44   }
  45   return n;
  46 }
  47
  48 bool IsDecimal(char c) {
  49   int d = TranslateDigit(c);
  50   return d >= 0 && d < 10;
  51 }
  52
  53 uptr ParseDecimal(const char **p) {
  54   return ParseNumber(p, 10);
  55 }
  56
  57 bool IsHex(char c) {
  58   int d = TranslateDigit(c);
  59   return d >= 0 && d < 16;
  60 }
  61
  62 uptr ParseHex(const char **p) {
  63   return ParseNumber(p, 16);
  64 }
  65
  66 void MemoryMappedSegment::AddAddressRanges(LoadedModule *module) {
  67   // data_ should be unused on this platform
  68   CHECK(!data_);
  69   module->addAddressRange(start, end, IsExecutable(), IsWritable());
  70 }
  71
  72 MemoryMappingLayout::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(&data_.proc_self_maps);
  80   if (cache_enabled && data_.proc_self_maps.mmaped_size == 0)
  81     LoadFromCache();
  82
  83   Reset();
  84 }
  85
  86 bool MemoryMappingLayout::Error() const {
  87   return data_.current == nullptr;
  88 }
  89
  90 MemoryMappingLayout::~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(data_.proc_self_maps.data, data_.proc_self_maps.mmaped_size);
  95 }
  96
  97 void MemoryMappingLayout::Reset() {
  98   data_.current = data_.proc_self_maps.data;
  99 }
 100
 101 // static
 102 void MemoryMappingLayout::CacheMemoryMappings() {
 103   ProcSelfMapsBuff new_proc_self_maps;
 104   ReadProcMaps(&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(cached_proc_self_maps.data, cached_proc_self_maps.mmaped_size);
 111   cached_proc_self_maps = new_proc_self_maps;
 112 }
 113
 114 void 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
 120 void 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); 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(cur_name, base_address);
 143     segment.AddAddressRanges(&cur_module);
 144     modules->push_back(cur_module);
 145   }
 146 }
 147
 148 #if SANITIZER_LINUX || SANITIZER_ANDROID || SANITIZER_SOLARIS || SANITIZER_NETBSD
 149 void GetMemoryProfile(fill_profile_f cb, uptr *stats) {
 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   ParseUnixMemoryProfile(cb, stats, smaps, smaps_len);
 156   UnmapOrDie(smaps, smaps_cap);
 157 }
 158
 159 void 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(pos[0])) {
 177       start = ParseHex(&pos);
 178       for (; *pos != '/' && *pos > '\n'; pos++) {}
 179       file = *pos == '/';
 180     } else if (internal_strncmp(pos, "Rss:", 4) == 0) {
 181       while (pos < end && !IsDecimal(*pos)) pos++;
 182       uptr rss = ParseDecimal(&pos) * 1024;
 183       cb(start, rss, file, stats);
 184     }
 185     while (*pos++ != '\n') {}
 186   }
 187 }
 188 #endif
 189
 190 } // namespace __sanitizer
 191
 192 #endif