1 //===-- sanitizer_coverage_libcdep_new.cpp --------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 // Sanitizer Coverage Controller for Trace PC Guard.
9 
10 #include "sanitizer_platform.h"
11 
12 #if !SANITIZER_FUCHSIA
13 #include "sancov_flags.h"
14 #include "sanitizer_allocator_internal.h"
15 #include "sanitizer_atomic.h"
16 #include "sanitizer_common.h"
17 #include "sanitizer_file.h"
18 
19 using namespace __sanitizer;
20 
21 using AddressRange = LoadedModule::AddressRange;
22 
23 namespace __sancov {
24 namespace {
25 
26 static const u64 Magic64 = 0xC0BFFFFFFFFFFF64ULL;
27 static const u64 Magic32 = 0xC0BFFFFFFFFFFF32ULL;
28 static const u64 Magic = SANITIZER_WORDSIZE == 64 ? Magic64 : Magic32;
29 
30 static fd_t OpenFile(const char* path) {
31   error_t err;
32   fd_t fd = OpenFile(path, WrOnly, &err);
33   if (fd == kInvalidFd)
34     Report("SanitizerCoverage: failed to open %s for writing (reason: %d)\n",
35            path, err);
36   return fd;
37 }
38 
39 static void GetCoverageFilename(char* path, const char* name,
40                                 const char* extension) {
41   CHECK(name);
42   internal_snprintf(path, kMaxPathLength, "%s/%s.%zd.%s",
43                     common_flags()->coverage_dir, name, internal_getpid(),
44                     extension);
45 }
46 
47 static void WriteModuleCoverage(char* file_path, const char* module_name,
48                                 const uptr* pcs, uptr len) {
49   GetCoverageFilename(file_path, StripModuleName(module_name), "sancov");
50   fd_t fd = OpenFile(file_path);
51   WriteToFile(fd, &Magic, sizeof(Magic));
52   WriteToFile(fd, pcs, len * sizeof(*pcs));
53   CloseFile(fd);
54   Printf("SanitizerCoverage: %s: %zd PCs written\n", file_path, len);
55 }
56 
57 static void SanitizerDumpCoverage(const uptr* unsorted_pcs, uptr len) {
58   if (!len) return;
59 
60   char* file_path = static_cast<char*>(InternalAlloc(kMaxPathLength));
61   char* module_name = static_cast<char*>(InternalAlloc(kMaxPathLength));
62   uptr* pcs = static_cast<uptr*>(InternalAlloc(len * sizeof(uptr)));
63 
64   internal_memcpy(pcs, unsorted_pcs, len * sizeof(uptr));
65   Sort(pcs, len);
66 
67   bool module_found = false;
68   uptr last_base = 0;
69   uptr module_start_idx = 0;
70 
71   for (uptr i = 0; i < len; ++i) {
72     const uptr pc = pcs[i];
73     if (!pc) continue;
74 
75     if (!GetModuleAndOffsetForPc(pc, nullptr, 0, &pcs[i])) {
76       Printf("ERROR: unknown pc 0x%zx (may happen if dlclose is used)\n", pc);
77       continue;
78     }
79     uptr module_base = pc - pcs[i];
80 
81     if (module_base != last_base || !module_found) {
82       if (module_found) {
83         WriteModuleCoverage(file_path, module_name, &pcs[module_start_idx],
84                             i - module_start_idx);
85       }
86 
87       last_base = module_base;
88       module_start_idx = i;
89       module_found = true;
90       GetModuleAndOffsetForPc(pc, module_name, kMaxPathLength, &pcs[i]);
91     }
92   }
93 
94   if (module_found) {
95     WriteModuleCoverage(file_path, module_name, &pcs[module_start_idx],
96                         len - module_start_idx);
97   }
98 
99   InternalFree(file_path);
100   InternalFree(module_name);
101   InternalFree(pcs);
102 }
103 
104 // Collects trace-pc guard coverage.
105 // This class relies on zero-initialization.
106 class TracePcGuardController {
107  public:
108   void Initialize() {
109     CHECK(!initialized);
110 
111     initialized = true;
112     InitializeSancovFlags();
113 
114     pc_vector.Initialize(0);
115   }
116 
117   void InitTracePcGuard(u32* start, u32* end) {
118     if (!initialized) Initialize();
119     CHECK(!*start);
120     CHECK_NE(start, end);
121 
122     u32 i = pc_vector.size();
123     for (u32* p = start; p < end; p++) *p = ++i;
124     pc_vector.resize(i);
125   }
126 
127   void TracePcGuard(u32* guard, uptr pc) {
128     u32 idx = *guard;
129     if (!idx) return;
130     // we start indices from 1.
131     atomic_uintptr_t* pc_ptr =
132         reinterpret_cast<atomic_uintptr_t*>(&pc_vector[idx - 1]);
133     if (atomic_load(pc_ptr, memory_order_relaxed) == 0)
134       atomic_store(pc_ptr, pc, memory_order_relaxed);
135   }
136 
137   void Reset() {
138     internal_memset(&pc_vector[0], 0, sizeof(pc_vector[0]) * pc_vector.size());
139   }
140 
141   void Dump() {
142     if (!initialized || !common_flags()->coverage) return;
143     __sanitizer_dump_coverage(pc_vector.data(), pc_vector.size());
144   }
145 
146  private:
147   bool initialized;
148   InternalMmapVectorNoCtor<uptr> pc_vector;
149 };
150 
151 static TracePcGuardController pc_guard_controller;
152 
153 // A basic default implementation of callbacks for
154 // -fsanitize-coverage=inline-8bit-counters,pc-table.
155 // Use TOOL_OPTIONS (UBSAN_OPTIONS, etc) to dump the coverage data:
156 // * cov_8bit_counters_out=PATH to dump the 8bit counters.
157 // * cov_pcs_out=PATH to dump the pc table.
158 //
159 // Most users will still need to define their own callbacks for greater
160 // flexibility.
161 namespace SingletonCounterCoverage {
162 
163 static char *counters_beg, *counters_end;
164 static const uptr *pcs_beg, *pcs_end;
165 
166 static void DumpCoverage() {
167   const char* file_path = common_flags()->cov_8bit_counters_out;
168   if (file_path && internal_strlen(file_path)) {
169     fd_t fd = OpenFile(file_path);
170     FileCloser file_closer(fd);
171     uptr size = counters_end - counters_beg;
172     WriteToFile(fd, counters_beg, size);
173     if (common_flags()->verbosity)
174       __sanitizer::Printf("cov_8bit_counters_out: written %zd bytes to %s\n",
175                           size, file_path);
176   }
177   file_path = common_flags()->cov_pcs_out;
178   if (file_path && internal_strlen(file_path)) {
179     fd_t fd = OpenFile(file_path);
180     FileCloser file_closer(fd);
181     uptr size = (pcs_end - pcs_beg) * sizeof(uptr);
182     WriteToFile(fd, pcs_beg, size);
183     if (common_flags()->verbosity)
184       __sanitizer::Printf("cov_pcs_out: written %zd bytes to %s\n", size,
185                           file_path);
186   }
187 }
188 
189 static void Cov8bitCountersInit(char* beg, char* end) {
190   counters_beg = beg;
191   counters_end = end;
192   Atexit(DumpCoverage);
193 }
194 
195 static void CovPcsInit(const uptr* beg, const uptr* end) {
196   pcs_beg = beg;
197   pcs_end = end;
198 }
199 
200 }  // namespace SingletonCounterCoverage
201 
202 }  // namespace
203 }  // namespace __sancov
204 
205 namespace __sanitizer {
206 void InitializeCoverage(bool enabled, const char *dir) {
207   static bool coverage_enabled = false;
208   if (coverage_enabled)
209     return;  // May happen if two sanitizer enable coverage in the same process.
210   coverage_enabled = enabled;
211   Atexit(__sanitizer_cov_dump);
212   AddDieCallback(__sanitizer_cov_dump);
213 }
214 } // namespace __sanitizer
215 
216 extern "C" {
217 SANITIZER_INTERFACE_ATTRIBUTE void __sanitizer_dump_coverage(const uptr* pcs,
218                                                              uptr len) {
219   return __sancov::SanitizerDumpCoverage(pcs, len);
220 }
221 
222 SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_trace_pc_guard, u32* guard) {
223   if (!*guard) return;
224   __sancov::pc_guard_controller.TracePcGuard(guard, GET_CALLER_PC() - 1);
225 }
226 
227 SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_trace_pc_guard_init,
228                              u32* start, u32* end) {
229   if (start == end || *start) return;
230   __sancov::pc_guard_controller.InitTracePcGuard(start, end);
231 }
232 
233 SANITIZER_INTERFACE_ATTRIBUTE void __sanitizer_dump_trace_pc_guard_coverage() {
234   __sancov::pc_guard_controller.Dump();
235 }
236 SANITIZER_INTERFACE_ATTRIBUTE void __sanitizer_cov_dump() {
237   __sanitizer_dump_trace_pc_guard_coverage();
238 }
239 SANITIZER_INTERFACE_ATTRIBUTE void __sanitizer_cov_reset() {
240   __sancov::pc_guard_controller.Reset();
241 }
242 // Default implementations (weak).
243 // Either empty or very simple.
244 // Most users should redefine them.
245 SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_trace_cmp, void) {}
246 SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_trace_cmp1, void) {}
247 SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_trace_cmp2, void) {}
248 SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_trace_cmp4, void) {}
249 SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_trace_cmp8, void) {}
250 SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_trace_const_cmp1, void) {}
251 SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_trace_const_cmp2, void) {}
252 SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_trace_const_cmp4, void) {}
253 SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_trace_const_cmp8, void) {}
254 SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_trace_switch, void) {}
255 SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_trace_div4, void) {}
256 SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_trace_div8, void) {}
257 SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_trace_gep, void) {}
258 SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_trace_pc_indir, void) {}
259 SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_8bit_counters_init,
260                              char* start, char* end) {
261   __sancov::SingletonCounterCoverage::Cov8bitCountersInit(start, end);
262 }
263 SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_bool_flag_init, void) {}
264 SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_pcs_init, const uptr* beg,
265                              const uptr* end) {
266   __sancov::SingletonCounterCoverage::CovPcsInit(beg, end);
267 }
268 }  // extern "C"
269 // Weak definition for code instrumented with -fsanitize-coverage=stack-depth
270 // and later linked with code containing a strong definition.
271 // E.g., -fsanitize=fuzzer-no-link
272 SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
273 SANITIZER_TLS_INITIAL_EXEC_ATTRIBUTE uptr __sancov_lowest_stack;
274 
275 #endif  // !SANITIZER_FUCHSIA
276