src/compiler-rt/lib/sanitizer_common/sanitizer_coverage_mapping_libcdep.cc

   1 //===-- sanitizer_coverage_mapping.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 // Mmap-based implementation of sanitizer coverage.
  11 //
  12 // This is part of the implementation of code coverage that does not require
  13 // __sanitizer_cov_dump() call. Data is stored in 2 files per process.
  14 //
  15 // $pid.sancov.map describes process memory layout in the following text-based
  16 // format:
  17 // <pointer size in bits>  // 1 line, 32 or 64
  18 // <mapping start> <mapping end> <base address> <dso name> // repeated
  19 // ...
  20 // Mapping lines are NOT sorted. This file is updated every time memory layout
  21 // is changed (i.e. in dlopen() and dlclose() interceptors).
  22 //
  23 // $pid.sancov.raw is a binary dump of PC values, sizeof(uptr) each. Again, not
  24 // sorted. This file is extended by 64Kb at a time and mapped into memory. It
  25 // contains one or more 0 words at the end, up to the next 64Kb aligned offset.
  26 //
  27 // To convert these 2 files to the usual .sancov format, run sancov.py rawunpack
  28 // $pid.sancov.raw.
  29 //
  30 //===----------------------------------------------------------------------===//
  31
  32 #include "sanitizer_allocator_internal.h"
  33 #include "sanitizer_libc.h"
  34 #include "sanitizer_procmaps.h"
  35
  36 namespace __sanitizer {
  37
  38 static const uptr kMaxTextSize = 64 * 1024;
  39
  40 struct CachedMapping {
  41  public:
  42   bool NeedsUpdate(uptr pc) {
  43     int new_pid = internal_getpid();
  44     if (last_pid == new_pid && pc && pc >= last_range_start &&
  45         pc < last_range_end)
  46       return false;
  47     last_pid = new_pid;
  48     return true;
  49   }
  50
  51   void SetModuleRange(uptr start, uptr end) {
  52     last_range_start = start;
  53     last_range_end = end;
  54   }
  55
  56  private:
  57   uptr last_range_start, last_range_end;
  58   int last_pid;
  59 };
  60
  61 static CachedMapping cached_mapping;
  62 static StaticSpinMutex mapping_mu;
  63
  64 void CovUpdateMapping(const char *coverage_dir, uptr caller_pc) {
  65   if (!common_flags()->coverage_direct) return;
  66
  67   SpinMutexLock l(&mapping_mu);
  68
  69   if (!cached_mapping.NeedsUpdate(caller_pc))
  70     return;
  71
  72   InternalScopedString text(kMaxTextSize);
  73
  74   {
  75     InternalScopedBuffer<LoadedModule> modules(kMaxNumberOfModules);
  76     CHECK(modules.data());
  77     int n_modules = GetListOfModules(modules.data(), kMaxNumberOfModules,
  78                                      /* filter */ nullptr);
  79
  80     text.append("%d\n", sizeof(uptr) * 8);
  81     for (int i = 0; i < n_modules; ++i) {
  82       const char *module_name = StripModuleName(modules[i].full_name());
  83       uptr base = modules[i].base_address();
  84       for (auto iter = modules[i].ranges(); iter.hasNext();) {
  85         const auto *range = iter.next();
  86         if (range->executable) {
  87           uptr start = range->beg;
  88           uptr end = range->end;
  89           text.append("%zx %zx %zx %s\n", start, end, base, module_name);
  90           if (caller_pc && caller_pc >= start && caller_pc < end)
  91             cached_mapping.SetModuleRange(start, end);
  92         }
  93       }
  94       modules[i].clear();
  95     }
  96   }
  97
  98   error_t err;
  99   InternalScopedString tmp_path(64 + internal_strlen(coverage_dir));
 100   uptr res = internal_snprintf((char *)tmp_path.data(), tmp_path.size(),
 101                                "%s/%zd.sancov.map.tmp", coverage_dir,
 102                                internal_getpid());
 103   CHECK_LE(res, tmp_path.size());
 104   fd_t map_fd = OpenFile(tmp_path.data(), WrOnly, &err);
 105   if (map_fd == kInvalidFd) {
 106     Report("Coverage: failed to open %s for writing: %d\n", tmp_path.data(),
 107            err);
 108     Die();
 109   }
 110
 111   if (!WriteToFile(map_fd, text.data(), text.length(), nullptr, &err)) {
 112     Printf("sancov.map write failed: %d\n", err);
 113     Die();
 114   }
 115   CloseFile(map_fd);
 116
 117   InternalScopedString path(64 + internal_strlen(coverage_dir));
 118   res = internal_snprintf((char *)path.data(), path.size(), "%s/%zd.sancov.map",
 119                           coverage_dir, internal_getpid());
 120   CHECK_LE(res, path.size());
 121   if (!RenameFile(tmp_path.data(), path.data(), &err)) {
 122     Printf("sancov.map rename failed: %d\n", err);
 123     Die();
 124   }
 125 }
 126
 127 } // namespace __sanitizer