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:
NeedsUpdate__sanitizer::CachedMapping42 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
SetModuleRange__sanitizer::CachedMapping51 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
CovUpdateMapping(const char * coverage_dir,uptr caller_pc)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 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