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
36namespace __sanitizer {
37
38static const uptr kMaxTextSize = 64 * 1024;
39
40struct 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
61static CachedMapping cached_mapping;
62static StaticSpinMutex mapping_mu;
63
64void 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    text.append("%d\n", sizeof(uptr) * 8);
76    ListOfModules modules;
77    modules.init();
78    for (const LoadedModule &module : modules) {
79      const char *module_name = StripModuleName(module.full_name());
80      uptr base = module.base_address();
81      for (const auto &range : module.ranges()) {
82        if (range.executable) {
83          uptr start = range.beg;
84          uptr end = range.end;
85          text.append("%zx %zx %zx %s\n", start, end, base, module_name);
86          if (caller_pc && caller_pc >= start && caller_pc < end)
87            cached_mapping.SetModuleRange(start, end);
88        }
89      }
90    }
91  }
92
93  error_t err;
94  InternalScopedString tmp_path(64 + internal_strlen(coverage_dir));
95  uptr res = internal_snprintf((char *)tmp_path.data(), tmp_path.size(),
96                               "%s/%zd.sancov.map.tmp", coverage_dir,
97                               internal_getpid());
98  CHECK_LE(res, tmp_path.size());
99  fd_t map_fd = OpenFile(tmp_path.data(), WrOnly, &err);
100  if (map_fd == kInvalidFd) {
101    Report("Coverage: failed to open %s for writing: %d\n", tmp_path.data(),
102           err);
103    Die();
104  }
105
106  if (!WriteToFile(map_fd, text.data(), text.length(), nullptr, &err)) {
107    Printf("sancov.map write failed: %d\n", err);
108    Die();
109  }
110  CloseFile(map_fd);
111
112  InternalScopedString path(64 + internal_strlen(coverage_dir));
113  res = internal_snprintf((char *)path.data(), path.size(), "%s/%zd.sancov.map",
114                          coverage_dir, internal_getpid());
115  CHECK_LE(res, path.size());
116  if (!RenameFile(tmp_path.data(), path.data(), &err)) {
117    Printf("sancov.map rename failed: %d\n", err);
118    Die();
119  }
120}
121
122} // namespace __sanitizer
123