examine_stack.cc (11453B)
1 // 2 // Copyright 2018 The Abseil Authors. 3 // 4 // Licensed under the Apache License, Version 2.0 (the "License"); 5 // you may not use this file except in compliance with the License. 6 // You may obtain a copy of the License at 7 // 8 // https://www.apache.org/licenses/LICENSE-2.0 9 // 10 // Unless required by applicable law or agreed to in writing, software 11 // distributed under the License is distributed on an "AS IS" BASIS, 12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 // See the License for the specific language governing permissions and 14 // limitations under the License. 15 // 16 17 #include "absl/debugging/internal/examine_stack.h" 18 19 #ifndef _WIN32 20 #include <unistd.h> 21 #endif 22 23 #include "absl/base/config.h" 24 25 #ifdef ABSL_HAVE_MMAP 26 #include <sys/mman.h> 27 #if defined(MAP_ANON) && !defined(MAP_ANONYMOUS) 28 #define MAP_ANONYMOUS MAP_ANON 29 #endif 30 #endif 31 32 #if defined(__linux__) || defined(__APPLE__) 33 #include <sys/ucontext.h> 34 #endif 35 36 #include <csignal> 37 #include <cstdio> 38 39 #include "absl/base/attributes.h" 40 #include "absl/base/internal/raw_logging.h" 41 #include "absl/base/macros.h" 42 #include "absl/debugging/stacktrace.h" 43 #include "absl/debugging/symbolize.h" 44 45 namespace absl { 46 ABSL_NAMESPACE_BEGIN 47 namespace debugging_internal { 48 49 namespace { 50 constexpr int kDefaultDumpStackFramesLimit = 64; 51 // The %p field width for printf() functions is two characters per byte, 52 // and two extra for the leading "0x". 53 constexpr int kPrintfPointerFieldWidth = 2 + 2 * sizeof(void*); 54 55 ABSL_CONST_INIT SymbolizeUrlEmitter debug_stack_trace_hook = nullptr; 56 57 // Async-signal safe mmap allocator. 58 void* Allocate(size_t num_bytes) { 59 #ifdef ABSL_HAVE_MMAP 60 void* p = ::mmap(nullptr, num_bytes, PROT_READ | PROT_WRITE, 61 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); 62 return p == MAP_FAILED ? nullptr : p; 63 #else 64 (void)num_bytes; 65 return nullptr; 66 #endif // ABSL_HAVE_MMAP 67 } 68 69 void Deallocate(void* p, size_t size) { 70 #ifdef ABSL_HAVE_MMAP 71 ::munmap(p, size); 72 #else 73 (void)p; 74 (void)size; 75 #endif // ABSL_HAVE_MMAP 76 } 77 78 // Print a program counter only. 79 void DumpPC(OutputWriter* writer, void* writer_arg, void* const pc, 80 const char* const prefix) { 81 char buf[100]; 82 snprintf(buf, sizeof(buf), "%s@ %*p\n", prefix, kPrintfPointerFieldWidth, pc); 83 writer(buf, writer_arg); 84 } 85 86 // Print a program counter and the corresponding stack frame size. 87 void DumpPCAndFrameSize(OutputWriter* writer, void* writer_arg, void* const pc, 88 int framesize, const char* const prefix) { 89 char buf[100]; 90 if (framesize <= 0) { 91 snprintf(buf, sizeof(buf), "%s@ %*p (unknown)\n", prefix, 92 kPrintfPointerFieldWidth, pc); 93 } else { 94 snprintf(buf, sizeof(buf), "%s@ %*p %9d\n", prefix, 95 kPrintfPointerFieldWidth, pc, framesize); 96 } 97 writer(buf, writer_arg); 98 } 99 100 // Print a program counter and the corresponding symbol. 101 void DumpPCAndSymbol(OutputWriter* writer, void* writer_arg, void* const pc, 102 const char* const prefix) { 103 char tmp[1024]; 104 const char* symbol = "(unknown)"; 105 // Symbolizes the previous address of pc because pc may be in the 106 // next function. The overrun happens when the function ends with 107 // a call to a function annotated noreturn (e.g. CHECK). 108 // If symbolization of pc-1 fails, also try pc on the off-chance 109 // that we crashed on the first instruction of a function (that 110 // actually happens very often for e.g. __restore_rt). 111 const uintptr_t prev_pc = reinterpret_cast<uintptr_t>(pc) - 1; 112 if (absl::Symbolize(reinterpret_cast<const char*>(prev_pc), tmp, 113 sizeof(tmp)) || 114 absl::Symbolize(pc, tmp, sizeof(tmp))) { 115 symbol = tmp; 116 } 117 char buf[1024]; 118 snprintf(buf, sizeof(buf), "%s@ %*p %s\n", prefix, kPrintfPointerFieldWidth, 119 pc, symbol); 120 writer(buf, writer_arg); 121 } 122 123 // Print a program counter, its stack frame size, and its symbol name. 124 // Note that there is a separate symbolize_pc argument. Return addresses may be 125 // at the end of the function, and this allows the caller to back up from pc if 126 // appropriate. 127 void DumpPCAndFrameSizeAndSymbol(OutputWriter* writer, void* writer_arg, 128 void* const pc, void* const symbolize_pc, 129 int framesize, const char* const prefix) { 130 char tmp[1024]; 131 const char* symbol = "(unknown)"; 132 if (absl::Symbolize(symbolize_pc, tmp, sizeof(tmp))) { 133 symbol = tmp; 134 } 135 char buf[1024]; 136 if (framesize <= 0) { 137 snprintf(buf, sizeof(buf), "%s@ %*p (unknown) %s\n", prefix, 138 kPrintfPointerFieldWidth, pc, symbol); 139 } else { 140 snprintf(buf, sizeof(buf), "%s@ %*p %9d %s\n", prefix, 141 kPrintfPointerFieldWidth, pc, framesize, symbol); 142 } 143 writer(buf, writer_arg); 144 } 145 146 } // namespace 147 148 void RegisterDebugStackTraceHook(SymbolizeUrlEmitter hook) { 149 debug_stack_trace_hook = hook; 150 } 151 152 SymbolizeUrlEmitter GetDebugStackTraceHook() { return debug_stack_trace_hook; } 153 154 // Returns the program counter from signal context, nullptr if 155 // unknown. vuc is a ucontext_t*. We use void* to avoid the use of 156 // ucontext_t on non-POSIX systems. 157 void* GetProgramCounter(void* const vuc) { 158 #ifdef __linux__ 159 if (vuc != nullptr) { 160 ucontext_t* context = reinterpret_cast<ucontext_t*>(vuc); 161 #if defined(__aarch64__) 162 return reinterpret_cast<void*>(context->uc_mcontext.pc); 163 #elif defined(__alpha__) 164 return reinterpret_cast<void*>(context->uc_mcontext.sc_pc); 165 #elif defined(__arm__) 166 return reinterpret_cast<void*>(context->uc_mcontext.arm_pc); 167 #elif defined(__hppa__) 168 return reinterpret_cast<void*>(context->uc_mcontext.sc_iaoq[0]); 169 #elif defined(__i386__) 170 if (14 < ABSL_ARRAYSIZE(context->uc_mcontext.gregs)) 171 return reinterpret_cast<void*>(context->uc_mcontext.gregs[14]); 172 #elif defined(__ia64__) 173 return reinterpret_cast<void*>(context->uc_mcontext.sc_ip); 174 #elif defined(__m68k__) 175 return reinterpret_cast<void*>(context->uc_mcontext.gregs[16]); 176 #elif defined(__mips__) 177 return reinterpret_cast<void*>(context->uc_mcontext.pc); 178 #elif defined(__powerpc64__) 179 return reinterpret_cast<void*>(context->uc_mcontext.gp_regs[32]); 180 #elif defined(__powerpc__) 181 return reinterpret_cast<void*>(context->uc_mcontext.uc_regs->gregs[32]); 182 #elif defined(__riscv) 183 return reinterpret_cast<void*>(context->uc_mcontext.__gregs[REG_PC]); 184 #elif defined(__s390__) && !defined(__s390x__) 185 return reinterpret_cast<void*>(context->uc_mcontext.psw.addr & 0x7fffffff); 186 #elif defined(__s390__) && defined(__s390x__) 187 return reinterpret_cast<void*>(context->uc_mcontext.psw.addr); 188 #elif defined(__sh__) 189 return reinterpret_cast<void*>(context->uc_mcontext.pc); 190 #elif defined(__sparc__) && !defined(__arch64__) 191 return reinterpret_cast<void*>(context->uc_mcontext.gregs[19]); 192 #elif defined(__sparc__) && defined(__arch64__) 193 return reinterpret_cast<void*>(context->uc_mcontext.mc_gregs[19]); 194 #elif defined(__x86_64__) 195 if (16 < ABSL_ARRAYSIZE(context->uc_mcontext.gregs)) 196 return reinterpret_cast<void*>(context->uc_mcontext.gregs[16]); 197 #elif defined(__e2k__) 198 return reinterpret_cast<void*>(context->uc_mcontext.cr0_hi); 199 #elif defined(__loongarch__) 200 return reinterpret_cast<void*>(context->uc_mcontext.__pc); 201 #else 202 #error "Undefined Architecture." 203 #endif 204 } 205 #elif defined(__APPLE__) 206 if (vuc != nullptr) { 207 ucontext_t* signal_ucontext = reinterpret_cast<ucontext_t*>(vuc); 208 #if defined(__aarch64__) 209 return reinterpret_cast<void*>( 210 __darwin_arm_thread_state64_get_pc(signal_ucontext->uc_mcontext->__ss)); 211 #elif defined(__arm__) 212 #if __DARWIN_UNIX03 213 return reinterpret_cast<void*>(signal_ucontext->uc_mcontext->__ss.__pc); 214 #else 215 return reinterpret_cast<void*>(signal_ucontext->uc_mcontext->ss.pc); 216 #endif 217 #elif defined(__i386__) 218 #if __DARWIN_UNIX03 219 return reinterpret_cast<void*>(signal_ucontext->uc_mcontext->__ss.__eip); 220 #else 221 return reinterpret_cast<void*>(signal_ucontext->uc_mcontext->ss.eip); 222 #endif 223 #elif defined(__x86_64__) 224 #if __DARWIN_UNIX03 225 return reinterpret_cast<void*>(signal_ucontext->uc_mcontext->__ss.__rip); 226 #else 227 return reinterpret_cast<void*>(signal_ucontext->uc_mcontext->ss.rip); 228 #endif 229 #endif 230 } 231 #elif defined(__akaros__) 232 auto* ctx = reinterpret_cast<struct user_context*>(vuc); 233 return reinterpret_cast<void*>(get_user_ctx_pc(ctx)); 234 #endif 235 static_cast<void>(vuc); 236 return nullptr; 237 } 238 239 void DumpPCAndFrameSizesAndStackTrace(void* const pc, void* const stack[], 240 int frame_sizes[], int depth, 241 int min_dropped_frames, 242 bool symbolize_stacktrace, 243 OutputWriter* writer, void* writer_arg) { 244 if (pc != nullptr) { 245 // We don't know the stack frame size for PC, use 0. 246 if (symbolize_stacktrace) { 247 DumpPCAndFrameSizeAndSymbol(writer, writer_arg, pc, pc, 0, "PC: "); 248 } else { 249 DumpPCAndFrameSize(writer, writer_arg, pc, 0, "PC: "); 250 } 251 } 252 for (int i = 0; i < depth; i++) { 253 if (symbolize_stacktrace) { 254 // Pass the previous address of pc as the symbol address because pc is a 255 // return address, and an overrun may occur when the function ends with a 256 // call to a function annotated noreturn (e.g. CHECK). Note that we don't 257 // do this for pc above, as the adjustment is only correct for return 258 // addresses. 259 DumpPCAndFrameSizeAndSymbol(writer, writer_arg, stack[i], 260 reinterpret_cast<char*>(stack[i]) - 1, 261 frame_sizes[i], " "); 262 } else { 263 DumpPCAndFrameSize(writer, writer_arg, stack[i], frame_sizes[i], " "); 264 } 265 } 266 if (min_dropped_frames > 0) { 267 char buf[100]; 268 snprintf(buf, sizeof(buf), " @ ... and at least %d more frames\n", 269 min_dropped_frames); 270 writer(buf, writer_arg); 271 } 272 } 273 274 // Dump current stack trace as directed by writer. 275 // Make sure this function is not inlined to avoid skipping too many top frames. 276 ABSL_ATTRIBUTE_NOINLINE 277 void DumpStackTrace(int min_dropped_frames, int max_num_frames, 278 bool symbolize_stacktrace, OutputWriter* writer, 279 void* writer_arg) { 280 // Print stack trace 281 void* stack_buf[kDefaultDumpStackFramesLimit]; 282 void** stack = stack_buf; 283 int num_stack = kDefaultDumpStackFramesLimit; 284 size_t allocated_bytes = 0; 285 286 if (num_stack >= max_num_frames) { 287 // User requested fewer frames than we already have space for. 288 num_stack = max_num_frames; 289 } else { 290 const size_t needed_bytes = 291 static_cast<size_t>(max_num_frames) * sizeof(stack[0]); 292 void* p = Allocate(needed_bytes); 293 if (p != nullptr) { // We got the space. 294 num_stack = max_num_frames; 295 stack = reinterpret_cast<void**>(p); 296 allocated_bytes = needed_bytes; 297 } 298 } 299 300 int depth = absl::GetStackTrace(stack, num_stack, min_dropped_frames + 1); 301 for (int i = 0; i < depth; i++) { 302 if (symbolize_stacktrace) { 303 DumpPCAndSymbol(writer, writer_arg, stack[static_cast<size_t>(i)], 304 " "); 305 } else { 306 DumpPC(writer, writer_arg, stack[static_cast<size_t>(i)], " "); 307 } 308 } 309 310 auto hook = GetDebugStackTraceHook(); 311 if (hook != nullptr) { 312 (*hook)(stack, depth, writer, writer_arg); 313 } 314 315 if (allocated_bytes != 0) Deallocate(stack, allocated_bytes); 316 } 317 318 } // namespace debugging_internal 319 ABSL_NAMESPACE_END 320 } // namespace absl