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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     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
128