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