libsanitizer/sanitizer_common/sanitizer_procmaps_common.cc

   1 //===-- sanitizer_procmaps_common.cc --------------------------------------===//
   2 //
   3 // This file is distributed under the University of Illinois Open Source
   4 // License. See LICENSE.TXT for details.
   5 //
   6 //===----------------------------------------------------------------------===//
   7 //
   8 // Information about the process mappings (common parts).
   9 //===----------------------------------------------------------------------===//
  10
  11 #include "sanitizer_platform.h"
  12
  13 #if SANITIZER_FREEBSD || SANITIZER_LINUX
  14
  15 #include "sanitizer_common.h"
  16 #include "sanitizer_placement_new.h"
  17 #include "sanitizer_procmaps.h"
  18
  19 namespace __sanitizer {
  20
  21 // Linker initialized.
  22 ProcSelfMapsBuff MemoryMappingLayout::cached_proc_self_maps_;
  23 StaticSpinMutex MemoryMappingLayout::cache_lock_;  // Linker initialized.
  24
  25 static int TranslateDigit(char c) {
  26   if (c >= '0' && c <= '9')
  27     return c - '0';
  28   if (c >= 'a' && c <= 'f')
  29     return c - 'a' + 10;
  30   if (c >= 'A' && c <= 'F')
  31     return c - 'A' + 10;
  32   return -1;
  33 }
  34
  35 // Parse a number and promote 'p' up to the first non-digit character.
  36 static uptr ParseNumber(const char **p, int base) {
  37   uptr n = 0;
  38   int d;
  39   CHECK(base >= 2 && base <= 16);
  40   while ((d = TranslateDigit(**p)) >= 0 && d < base) {
  41     n = n * base + d;
  42     (*p)++;
  43   }
  44   return n;
  45 }
  46
  47 bool IsDecimal(char c) {
  48   int d = TranslateDigit(c);
  49   return d >= 0 && d < 10;
  50 }
  51
  52 uptr ParseDecimal(const char **p) {
  53   return ParseNumber(p, 10);
  54 }
  55
  56 bool IsHex(char c) {
  57   int d = TranslateDigit(c);
  58   return d >= 0 && d < 16;
  59 }
  60
  61 uptr ParseHex(const char **p) {
  62   return ParseNumber(p, 16);
  63 }
  64
  65 MemoryMappingLayout::MemoryMappingLayout(bool cache_enabled) {
  66   ReadProcMaps(&proc_self_maps_);
  67   if (cache_enabled) {
  68     if (proc_self_maps_.mmaped_size == 0) {
  69       LoadFromCache();
  70       CHECK_GT(proc_self_maps_.len, 0);
  71     }
  72   } else {
  73     CHECK_GT(proc_self_maps_.mmaped_size, 0);
  74   }
  75   Reset();
  76   // FIXME: in the future we may want to cache the mappings on demand only.
  77   if (cache_enabled)
  78     CacheMemoryMappings();
  79 }
  80
  81 MemoryMappingLayout::~MemoryMappingLayout() {
  82   // Only unmap the buffer if it is different from the cached one. Otherwise
  83   // it will be unmapped when the cache is refreshed.
  84   if (proc_self_maps_.data != cached_proc_self_maps_.data) {
  85     UnmapOrDie(proc_self_maps_.data, proc_self_maps_.mmaped_size);
  86   }
  87 }
  88
  89 void MemoryMappingLayout::Reset() {
  90   current_ = proc_self_maps_.data;
  91 }
  92
  93 // static
  94 void MemoryMappingLayout::CacheMemoryMappings() {
  95   SpinMutexLock l(&cache_lock_);
  96   // Don't invalidate the cache if the mappings are unavailable.
  97   ProcSelfMapsBuff old_proc_self_maps;
  98   old_proc_self_maps = cached_proc_self_maps_;
  99   ReadProcMaps(&cached_proc_self_maps_);
 100   if (cached_proc_self_maps_.mmaped_size == 0) {
 101     cached_proc_self_maps_ = old_proc_self_maps;
 102   } else {
 103     if (old_proc_self_maps.mmaped_size) {
 104       UnmapOrDie(old_proc_self_maps.data,
 105                  old_proc_self_maps.mmaped_size);
 106     }
 107   }
 108 }
 109
 110 void MemoryMappingLayout::LoadFromCache() {
 111   SpinMutexLock l(&cache_lock_);
 112   if (cached_proc_self_maps_.data) {
 113     proc_self_maps_ = cached_proc_self_maps_;
 114   }
 115 }
 116
 117 void MemoryMappingLayout::DumpListOfModules(
 118     InternalMmapVector<LoadedModule> *modules) {
 119   Reset();
 120   uptr cur_beg, cur_end, cur_offset, prot;
 121   InternalScopedString module_name(kMaxPathLength);
 122   for (uptr i = 0; Next(&cur_beg, &cur_end, &cur_offset, module_name.data(),
 123                         module_name.size(), &prot);
 124        i++) {
 125     const char *cur_name = module_name.data();
 126     if (cur_name[0] == '\0')
 127       continue;
 128     // Don't subtract 'cur_beg' from the first entry:
 129     // * If a binary is compiled w/o -pie, then the first entry in
 130     //   process maps is likely the binary itself (all dynamic libs
 131     //   are mapped higher in address space). For such a binary,
 132     //   instruction offset in binary coincides with the actual
 133     //   instruction address in virtual memory (as code section
 134     //   is mapped to a fixed memory range).
 135     // * If a binary is compiled with -pie, all the modules are
 136     //   mapped high at address space (in particular, higher than
 137     //   shadow memory of the tool), so the module can't be the
 138     //   first entry.
 139     uptr base_address = (i ? cur_beg : 0) - cur_offset;
 140     LoadedModule cur_module;
 141     cur_module.set(cur_name, base_address);
 142     cur_module.addAddressRange(cur_beg, cur_end, prot & kProtectionExecute);
 143     modules->push_back(cur_module);
 144   }
 145 }
 146
 147 void GetMemoryProfile(fill_profile_f cb, uptr *stats, uptr stats_size) {
 148   char *smaps = nullptr;
 149   uptr smaps_cap = 0;
 150   uptr smaps_len = 0;
 151   if (!ReadFileToBuffer("/proc/self/smaps", &smaps, &smaps_cap, &smaps_len))
 152     return;
 153   uptr start = 0;
 154   bool file = false;
 155   const char *pos = smaps;
 156   while (pos < smaps + smaps_len) {
 157     if (IsHex(pos[0])) {
 158       start = ParseHex(&pos);
 159       for (; *pos != '/' && *pos > '\n'; pos++) {}
 160       file = *pos == '/';
 161     } else if (internal_strncmp(pos, "Rss:", 4) == 0) {
 162       while (!IsDecimal(*pos)) pos++;
 163       uptr rss = ParseDecimal(&pos) * 1024;
 164       cb(start, rss, file, stats, stats_size);
 165     }
 166     while (*pos++ != '\n') {}
 167   }
 168   UnmapOrDie(smaps, smaps_cap);
 169 }
 170
 171 } // namespace __sanitizer
 172
 173 #endif // SANITIZER_FREEBSD || SANITIZER_LINUX