libsanitizer/sanitizer_common/sanitizer_coverage_mapping_libcdep.cc

   1 //===-- sanitizer_coverage_mapping.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 // Mmap-based implementation of sanitizer coverage.
   9 //
  10 // This is part of the implementation of code coverage that does not require
  11 // __sanitizer_cov_dump() call. Data is stored in 2 files per process.
  12 //
  13 // $pid.sancov.map describes process memory layout in the following text-based
  14 // format:
  15 // <pointer size in bits>  // 1 line, 32 or 64
  16 // <mapping start> <mapping end> <base address> <dso name> // repeated
  17 // ...
  18 // Mapping lines are NOT sorted. This file is updated every time memory layout
  19 // is changed (i.e. in dlopen() and dlclose() interceptors).
  20 //
  21 // $pid.sancov.raw is a binary dump of PC values, sizeof(uptr) each. Again, not
  22 // sorted. This file is extended by 64Kb at a time and mapped into memory. It
  23 // contains one or more 0 words at the end, up to the next 64Kb aligned offset.
  24 //
  25 // To convert these 2 files to the usual .sancov format, run sancov.py rawunpack
  26 // $pid.sancov.raw.
  27 //
  28 //===----------------------------------------------------------------------===//
  29
  30 #include "sanitizer_allocator_internal.h"
  31 #include "sanitizer_libc.h"
  32 #include "sanitizer_procmaps.h"
  33
  34 namespace __sanitizer {
  35
  36 static const uptr kMaxTextSize = 64 * 1024;
  37
  38 struct CachedMapping {
  39  public:
  40   bool NeedsUpdate(uptr pc) {
  41     int new_pid = internal_getpid();
  42     if (last_pid == new_pid && pc && pc >= last_range_start &&
  43         pc < last_range_end)
  44       return false;
  45     last_pid = new_pid;
  46     return true;
  47   }
  48
  49   void SetModuleRange(uptr start, uptr end) {
  50     last_range_start = start;
  51     last_range_end = end;
  52   }
  53
  54  private:
  55   uptr last_range_start, last_range_end;
  56   int last_pid;
  57 };
  58
  59 static CachedMapping cached_mapping;
  60 static StaticSpinMutex mapping_mu;
  61
  62 void CovUpdateMapping(const char *coverage_dir, uptr caller_pc) {
  63   if (!common_flags()->coverage_direct) return;
  64
  65   SpinMutexLock l(&mapping_mu);
  66
  67   if (!cached_mapping.NeedsUpdate(caller_pc))
  68     return;
  69
  70   InternalScopedString text(kMaxTextSize);
  71
  72   {
  73     text.append("%d\n", sizeof(uptr) * 8);
  74     ListOfModules modules;
  75     modules.init();
  76     for (const LoadedModule &module : modules) {
  77       const char *module_name = StripModuleName(module.full_name());
  78       uptr base = module.base_address();
  79       for (const auto &range : module.ranges()) {
  80         if (range.executable) {
  81           uptr start = range.beg;
  82           uptr end = range.end;
  83           text.append("%zx %zx %zx %s\n", start, end, base, module_name);
  84           if (caller_pc && caller_pc >= start && caller_pc < end)
  85             cached_mapping.SetModuleRange(start, end);
  86         }
  87       }
  88     }
  89   }
  90
  91   error_t err;
  92   InternalScopedString tmp_path(64 + internal_strlen(coverage_dir));
  93   uptr res = internal_snprintf((char *)tmp_path.data(), tmp_path.size(),
  94                                "%s/%zd.sancov.map.tmp", coverage_dir,
  95                                internal_getpid());
  96   CHECK_LE(res, tmp_path.size());
  97   fd_t map_fd = OpenFile(tmp_path.data(), WrOnly, &err);
  98   if (map_fd == kInvalidFd) {
  99     Report("Coverage: failed to open %s for writing: %d\n", tmp_path.data(),
 100            err);
 101     Die();
 102   }
 103
 104   if (!WriteToFile(map_fd, text.data(), text.length(), nullptr, &err)) {
 105     Printf("sancov.map write failed: %d\n", err);
 106     Die();
 107   }
 108   CloseFile(map_fd);
 109
 110   InternalScopedString path(64 + internal_strlen(coverage_dir));
 111   res = internal_snprintf((char *)path.data(), path.size(), "%s/%zd.sancov.map",
 112                           coverage_dir, internal_getpid());
 113   CHECK_LE(res, path.size());
 114   if (!RenameFile(tmp_path.data(), path.data(), &err)) {
 115     Printf("sancov.map rename failed: %d\n", err);
 116     Die();
 117   }
 118 }
 119
 120 } // namespace __sanitizer