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 #if defined(__powerpc__) || defined(__powerpc64__)
  35   // PCs are always 4 byte aligned.
  36   return pc - 4;
  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     uptr pc = patch_pc(addr[i]);
  71     uptr addr_frames_num = 0;  // The number of stack frames for current
  72                                // instruction address.
  73     if (symbolize_callback) {
  74       if (symbolize_callback((void*)pc, buff.data(), buff.size())) {
  75         addr_frames_num = 1;
  76         PrintStackFramePrefix(frame_num, pc);
  77         // We can't know anything about the string returned by external
  78         // symbolizer, but if it starts with filename, try to strip path prefix
  79         // from it.
  80         Printf(" %s\n", StripPathPrefix(buff.data(), strip_file_prefix));
  81         frame_num++;
  82       }
  83     }
  84     if (symbolize && addr_frames_num == 0) {
  85       // Use our own (online) symbolizer, if necessary.
  86       addr_frames_num = SymbolizeCode(pc, addr_frames.data(),
  87                                       addr_frames.size());
  88       for (uptr j = 0; j < addr_frames_num; j++) {
  89         AddressInfo &info = addr_frames[j];
  90         PrintStackFramePrefix(frame_num, pc);
  91         if (info.function) {
  92           Printf(" in %s", info.function);
  93         }
  94         if (info.file) {
  95           PrintSourceLocation(info.file, info.line, info.column,
  96                               strip_file_prefix);
  97         } else if (info.module) {
  98           PrintModuleAndOffset(info.module, info.module_offset,
  99                                strip_file_prefix);
 100         }
 101         Printf("\n");
 102         info.Clear();
 103         frame_num++;
 104       }
 105     }
 106     if (addr_frames_num == 0) {
 107       // If online symbolization failed, try to output at least module and
 108       // offset for instruction.
 109       PrintStackFramePrefix(frame_num, pc);
 110       uptr offset;
 111       if (proc_maps.GetObjectNameAndOffset(pc, &offset,
 112                                            buff.data(), buff.size())) {
 113         PrintModuleAndOffset(buff.data(), offset, strip_file_prefix);
 114       }
 115       Printf("\n");
 116       frame_num++;
 117     }
 118   }
 119 }
 120
 121 uptr StackTrace::GetCurrentPc() {
 122   return GET_CALLER_PC();
 123 }
 124
 125 void StackTrace::FastUnwindStack(uptr pc, uptr bp,
 126                                  uptr stack_top, uptr stack_bottom) {
 127   CHECK(size == 0 && trace[0] == pc);
 128   size = 1;
 129   uhwptr *frame = (uhwptr *)bp;
 130   uhwptr *prev_frame = frame;
 131   while (frame >= prev_frame &&
 132          frame < (uhwptr *)stack_top - 2 &&
 133          frame > (uhwptr *)stack_bottom &&
 134          size < max_size) {
 135     uhwptr pc1 = frame[1];
 136     if (pc1 != pc) {
 137       trace[size++] = (uptr) pc1;
 138     }
 139     prev_frame = frame;
 140     frame = (uhwptr *)frame[0];
 141   }
 142 }
 143
 144 void StackTrace::PopStackFrames(uptr count) {
 145   CHECK(size >= count);
 146   size -= count;
 147   for (uptr i = 0; i < size; i++) {
 148     trace[i] = trace[i + count];
 149   }
 150 }
 151
 152 // On 32-bits we don't compress stack traces.
 153 // On 64-bits we compress stack traces: if a given pc differes slightly from
 154 // the previous one, we record a 31-bit offset instead of the full pc.
 155 SANITIZER_INTERFACE_ATTRIBUTE
 156 uptr StackTrace::CompressStack(StackTrace *stack, u32 *compressed, uptr size) {
 157 #if SANITIZER_WORDSIZE == 32
 158   // Don't compress, just copy.
 159   uptr res = 0;
 160   for (uptr i = 0; i < stack->size && i < size; i++) {
 161     compressed[i] = stack->trace[i];
 162     res++;
 163   }
 164   if (stack->size < size)
 165     compressed[stack->size] = 0;
 166 #else  // 64 bits, compress.
 167   uptr prev_pc = 0;
 168   const uptr kMaxOffset = (1ULL << 30) - 1;
 169   uptr c_index = 0;
 170   uptr res = 0;
 171   for (uptr i = 0, n = stack->size; i < n; i++) {
 172     uptr pc = stack->trace[i];
 173     if (!pc) break;
 174     if ((s64)pc < 0) break;
 175     // Printf("C pc[%zu] %zx\n", i, pc);
 176     if (prev_pc - pc < kMaxOffset || pc - prev_pc < kMaxOffset) {
 177       uptr offset = (s64)(pc - prev_pc);
 178       offset |= (1U << 31);
 179       if (c_index >= size) break;
 180       // Printf("C co[%zu] offset %zx\n", i, offset);
 181       compressed[c_index++] = offset;
 182     } else {
 183       uptr hi = pc >> 32;
 184       uptr lo = (pc << 32) >> 32;
 185       CHECK_EQ((hi & (1 << 31)), 0);
 186       if (c_index + 1 >= size) break;
 187       // Printf("C co[%zu] hi/lo: %zx %zx\n", c_index, hi, lo);
 188       compressed[c_index++] = hi;
 189       compressed[c_index++] = lo;
 190     }
 191     res++;
 192     prev_pc = pc;
 193   }
 194   if (c_index < size)
 195     compressed[c_index] = 0;
 196   if (c_index + 1 < size)
 197     compressed[c_index + 1] = 0;
 198 #endif  // SANITIZER_WORDSIZE
 199
 200   // debug-only code
 201 #if 0
 202   StackTrace check_stack;
 203   UncompressStack(&check_stack, compressed, size);
 204   if (res < check_stack.size) {
 205     Printf("res %zu check_stack.size %zu; c_size %zu\n", res,
 206            check_stack.size, size);
 207   }
 208   // |res| may be greater than check_stack.size, because
 209   // UncompressStack(CompressStack(stack)) eliminates the 0x0 frames.
 210   CHECK(res >= check_stack.size);
 211   CHECK_EQ(0, REAL(memcmp)(check_stack.trace, stack->trace,
 212                           check_stack.size * sizeof(uptr)));
 213 #endif
 214
 215   return res;
 216 }
 217
 218 SANITIZER_INTERFACE_ATTRIBUTE
 219 void StackTrace::UncompressStack(StackTrace *stack,
 220                                  u32 *compressed, uptr size) {
 221 #if SANITIZER_WORDSIZE == 32
 222   // Don't uncompress, just copy.
 223   stack->size = 0;
 224   for (uptr i = 0; i < size && i < kStackTraceMax; i++) {
 225     if (!compressed[i]) break;
 226     stack->size++;
 227     stack->trace[i] = compressed[i];
 228   }
 229 #else  // 64 bits, uncompress
 230   uptr prev_pc = 0;
 231   stack->size = 0;
 232   for (uptr i = 0; i < size && stack->size < kStackTraceMax; i++) {
 233     u32 x = compressed[i];
 234     uptr pc = 0;
 235     if (x & (1U << 31)) {
 236       // Printf("U co[%zu] offset: %x\n", i, x);
 237       // this is an offset
 238       s32 offset = x;
 239       offset = (offset << 1) >> 1;  // remove the 31-byte and sign-extend.
 240       pc = prev_pc + offset;
 241       CHECK(pc);
 242     } else {
 243       // CHECK(i + 1 < size);
 244       if (i + 1 >= size) break;
 245       uptr hi = x;
 246       uptr lo = compressed[i+1];
 247       // Printf("U co[%zu] hi/lo: %zx %zx\n", i, hi, lo);
 248       i++;
 249       pc = (hi << 32) | lo;
 250       if (!pc) break;
 251     }
 252     // Printf("U pc[%zu] %zx\n", stack->size, pc);
 253     stack->trace[stack->size++] = pc;
 254     prev_pc = pc;
 255   }
 256 #endif  // SANITIZER_WORDSIZE
 257 }
 258
 259 }  // namespace __sanitizer