libsanitizer/sanitizer_common/sanitizer_stacktrace.cc

   1 //===-- sanitizer_stacktrace.cc -------------------------------------------===//
   2 //
   3 // This file is distributed under the University of Illinois Open Source
   4 // License. See LICENSE.TXT for details.
   5 //
   6 //===----------------------------------------------------------------------===//
   7 //
   8 // This file is shared between AddressSanitizer and ThreadSanitizer
   9 // run-time libraries.
  10 //===----------------------------------------------------------------------===//
  11
  12 #include "sanitizer_common.h"
  13 #include "sanitizer_procmaps.h"
  14 #include "sanitizer_stacktrace.h"
  15 #include "sanitizer_symbolizer.h"
  16
  17 namespace __sanitizer {
  18 const char *StripPathPrefix(const char *filepath,
  19                             const char *strip_file_prefix) {
  20   if (filepath == 0) return 0;
  21   if (filepath == internal_strstr(filepath, strip_file_prefix))
  22     return filepath + internal_strlen(strip_file_prefix);
  23   return filepath;
  24 }
  25
  26 // ----------------------- StackTrace ----------------------------- {{{1
  27 uptr StackTrace::GetPreviousInstructionPc(uptr pc) {
  28 #ifdef __arm__
  29   // Cancel Thumb bit.
  30   pc = pc & (~1);
  31 #endif
  32 #if defined(__powerpc__) || defined(__powerpc64__)
  33   // PCs are always 4 byte aligned.
  34   return pc - 4;
  35 #elif defined(__sparc__)
  36   return pc - 8;
  37 #else
  38   return pc - 1;
  39 #endif
  40 }
  41
  42 static void PrintStackFramePrefix(uptr frame_num, uptr pc) {
  43   Printf("    #%zu 0x%zx", frame_num, pc);
  44 }
  45
  46 static void PrintSourceLocation(const char *file, int line, int column,
  47                                 const char *strip_file_prefix) {
  48   CHECK(file);
  49   Printf(" %s", StripPathPrefix(file, strip_file_prefix));
  50   if (line > 0) {
  51     Printf(":%d", line);
  52     if (column > 0)
  53       Printf(":%d", column);
  54   }
  55 }
  56
  57 static void PrintModuleAndOffset(const char *module, uptr offset,
  58                                  const char *strip_file_prefix) {
  59   Printf(" (%s+0x%zx)", StripPathPrefix(module, strip_file_prefix), offset);
  60 }
  61
  62 void StackTrace::PrintStack(const uptr *addr, uptr size,
  63                             bool symbolize, const char *strip_file_prefix,
  64                             SymbolizeCallback symbolize_callback ) {
  65   MemoryMappingLayout proc_maps;
  66   InternalScopedBuffer<char> buff(GetPageSizeCached() * 2);
  67   InternalScopedBuffer<AddressInfo> addr_frames(64);
  68   uptr frame_num = 0;
  69   for (uptr i = 0; i < size && addr[i]; i++) {
  70     // PCs in stack traces are actually the return addresses, that is,
  71     // addresses of the next instructions after the call.
  72     uptr pc = GetPreviousInstructionPc(addr[i]);
  73     uptr addr_frames_num = 0;  // The number of stack frames for current
  74                                // instruction address.
  75     if (symbolize_callback) {
  76       if (symbolize_callback((void*)pc, buff.data(), buff.size())) {
  77         addr_frames_num = 1;
  78         PrintStackFramePrefix(frame_num, pc);
  79         // We can't know anything about the string returned by external
  80         // symbolizer, but if it starts with filename, try to strip path prefix
  81         // from it.
  82         Printf(" %s\n", StripPathPrefix(buff.data(), strip_file_prefix));
  83         frame_num++;
  84       }
  85     }
  86     if (symbolize && addr_frames_num == 0) {
  87       // Use our own (online) symbolizer, if necessary.
  88       addr_frames_num = SymbolizeCode(pc, addr_frames.data(),
  89                                       addr_frames.size());
  90       for (uptr j = 0; j < addr_frames_num; j++) {
  91         AddressInfo &info = addr_frames[j];
  92         PrintStackFramePrefix(frame_num, pc);
  93         if (info.function) {
  94           Printf(" in %s", info.function);
  95         }
  96         if (info.file) {
  97           PrintSourceLocation(info.file, info.line, info.column,
  98                               strip_file_prefix);
  99         } else if (info.module) {
 100           PrintModuleAndOffset(info.module, info.module_offset,
 101                                strip_file_prefix);
 102         }
 103         Printf("\n");
 104         info.Clear();
 105         frame_num++;
 106       }
 107     }
 108     if (addr_frames_num == 0) {
 109       // If online symbolization failed, try to output at least module and
 110       // offset for instruction.
 111       PrintStackFramePrefix(frame_num, pc);
 112       uptr offset;
 113       if (proc_maps.GetObjectNameAndOffset(pc, &offset,
 114                                            buff.data(), buff.size())) {
 115         PrintModuleAndOffset(buff.data(), offset, strip_file_prefix);
 116       }
 117       Printf("\n");
 118       frame_num++;
 119     }
 120   }
 121 }
 122
 123 uptr StackTrace::GetCurrentPc() {
 124   return GET_CALLER_PC();
 125 }
 126
 127 void StackTrace::FastUnwindStack(uptr pc, uptr bp,
 128                                  uptr stack_top, uptr stack_bottom) {
 129   CHECK(size == 0 && trace[0] == pc);
 130   size = 1;
 131   uhwptr *frame = (uhwptr *)bp;
 132   uhwptr *prev_frame = frame - 1;
 133   // Avoid infinite loop when frame == frame[0] by using frame > prev_frame.
 134   while (frame > prev_frame &&
 135          frame < (uhwptr *)stack_top - 2 &&
 136          frame > (uhwptr *)stack_bottom &&
 137          size < max_size) {
 138     uhwptr pc1 = frame[1];
 139     if (pc1 != pc) {
 140       trace[size++] = (uptr) pc1;
 141     }
 142     prev_frame = frame;
 143     frame = (uhwptr *)frame[0];
 144   }
 145 }
 146
 147 void StackTrace::PopStackFrames(uptr count) {
 148   CHECK(size >= count);
 149   size -= count;
 150   for (uptr i = 0; i < size; i++) {
 151     trace[i] = trace[i + count];
 152   }
 153 }
 154
 155 // On 32-bits we don't compress stack traces.
 156 // On 64-bits we compress stack traces: if a given pc differes slightly from
 157 // the previous one, we record a 31-bit offset instead of the full pc.
 158 SANITIZER_INTERFACE_ATTRIBUTE
 159 uptr StackTrace::CompressStack(StackTrace *stack, u32 *compressed, uptr size) {
 160 #if SANITIZER_WORDSIZE == 32
 161   // Don't compress, just copy.
 162   uptr res = 0;
 163   for (uptr i = 0; i < stack->size && i < size; i++) {
 164     compressed[i] = stack->trace[i];
 165     res++;
 166   }
 167   if (stack->size < size)
 168     compressed[stack->size] = 0;
 169 #else  // 64 bits, compress.
 170   uptr prev_pc = 0;
 171   const uptr kMaxOffset = (1ULL << 30) - 1;
 172   uptr c_index = 0;
 173   uptr res = 0;
 174   for (uptr i = 0, n = stack->size; i < n; i++) {
 175     uptr pc = stack->trace[i];
 176     if (!pc) break;
 177     if ((s64)pc < 0) break;
 178     // Printf("C pc[%zu] %zx\n", i, pc);
 179     if (prev_pc - pc < kMaxOffset || pc - prev_pc < kMaxOffset) {
 180       uptr offset = (s64)(pc - prev_pc);
 181       offset |= (1U << 31);
 182       if (c_index >= size) break;
 183       // Printf("C co[%zu] offset %zx\n", i, offset);
 184       compressed[c_index++] = offset;
 185     } else {
 186       uptr hi = pc >> 32;
 187       uptr lo = (pc << 32) >> 32;
 188       CHECK_EQ((hi & (1 << 31)), 0);
 189       if (c_index + 1 >= size) break;
 190       // Printf("C co[%zu] hi/lo: %zx %zx\n", c_index, hi, lo);
 191       compressed[c_index++] = hi;
 192       compressed[c_index++] = lo;
 193     }
 194     res++;
 195     prev_pc = pc;
 196   }
 197   if (c_index < size)
 198     compressed[c_index] = 0;
 199   if (c_index + 1 < size)
 200     compressed[c_index + 1] = 0;
 201 #endif  // SANITIZER_WORDSIZE
 202
 203   // debug-only code
 204 #if 0
 205   StackTrace check_stack;
 206   UncompressStack(&check_stack, compressed, size);
 207   if (res < check_stack.size) {
 208     Printf("res %zu check_stack.size %zu; c_size %zu\n", res,
 209            check_stack.size, size);
 210   }
 211   // |res| may be greater than check_stack.size, because
 212   // UncompressStack(CompressStack(stack)) eliminates the 0x0 frames.
 213   CHECK(res >= check_stack.size);
 214   CHECK_EQ(0, REAL(memcmp)(check_stack.trace, stack->trace,
 215                           check_stack.size * sizeof(uptr)));
 216 #endif
 217
 218   return res;
 219 }
 220
 221 SANITIZER_INTERFACE_ATTRIBUTE
 222 void StackTrace::UncompressStack(StackTrace *stack,
 223                                  u32 *compressed, uptr size) {
 224 #if SANITIZER_WORDSIZE == 32
 225   // Don't uncompress, just copy.
 226   stack->size = 0;
 227   for (uptr i = 0; i < size && i < kStackTraceMax; i++) {
 228     if (!compressed[i]) break;
 229     stack->size++;
 230     stack->trace[i] = compressed[i];
 231   }
 232 #else  // 64 bits, uncompress
 233   uptr prev_pc = 0;
 234   stack->size = 0;
 235   for (uptr i = 0; i < size && stack->size < kStackTraceMax; i++) {
 236     u32 x = compressed[i];
 237     uptr pc = 0;
 238     if (x & (1U << 31)) {
 239       // Printf("U co[%zu] offset: %x\n", i, x);
 240       // this is an offset
 241       s32 offset = x;
 242       offset = (offset << 1) >> 1;  // remove the 31-byte and sign-extend.
 243       pc = prev_pc + offset;
 244       CHECK(pc);
 245     } else {
 246       // CHECK(i + 1 < size);
 247       if (i + 1 >= size) break;
 248       uptr hi = x;
 249       uptr lo = compressed[i+1];
 250       // Printf("U co[%zu] hi/lo: %zx %zx\n", i, hi, lo);
 251       i++;
 252       pc = (hi << 32) | lo;
 253       if (!pc) break;
 254     }
 255     // Printf("U pc[%zu] %zx\n", stack->size, pc);
 256     stack->trace[stack->size++] = pc;
 257     prev_pc = pc;
 258   }
 259 #endif  // SANITIZER_WORDSIZE
 260 }
 261
 262 }  // namespace __sanitizer