sanitizer_stacktrace.cc revision e89f1846d58550f919a0ef9081b11d4b0405019d 
1//===-- sanitizer_stacktrace.cc -------------------------------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file is shared between AddressSanitizer and ThreadSanitizer
11// run-time libraries.
12//===----------------------------------------------------------------------===//
13
14#include "sanitizer_common.h"
15#include "sanitizer_procmaps.h"
16#include "sanitizer_stacktrace.h"
17#include "sanitizer_symbolizer.h"
18
19namespace __sanitizer {
20static const char *StripPathPrefix(const char *filepath,
21                                   const char *strip_file_prefix) {
22  if (filepath == internal_strstr(filepath, strip_file_prefix))
23    return filepath + internal_strlen(strip_file_prefix);
24  return filepath;
25}
26
27// ----------------------- StackTrace ----------------------------- {{{1
28// PCs in stack traces are actually the return addresses, that is,
29// addresses of the next instructions after the call. That's why we
30// decrement them.
31static uptr patch_pc(uptr pc) {
32#ifdef __arm__
33  // Cancel Thumb bit.
34  pc = pc & (~1);
35#endif
36#if defined(__powerpc__) || defined(__powerpc64__)
37  // PCs are always 4 byte aligned.
38  return pc - 4;
39#else
40  return pc - 1;
41#endif
42}
43
44static void PrintStackFramePrefix(uptr frame_num, uptr pc) {
45  Printf("    #%zu 0x%zx", frame_num, pc);
46}
47
48static void PrintSourceLocation(const char *file, int line, int column,
49                                const char *strip_file_prefix) {
50  CHECK(file);
51  Printf(" %s", StripPathPrefix(file, strip_file_prefix));
52  if (line > 0) {
53    Printf(":%d", line);
54    if (column > 0)
55      Printf(":%d", column);
56  }
57}
58
59static void PrintModuleAndOffset(const char *module, uptr offset,
60                                 const char *strip_file_prefix) {
61  Printf(" (%s+0x%zx)", StripPathPrefix(module, strip_file_prefix), offset);
62}
63
64void StackTrace::PrintStack(const uptr *addr, uptr size,
65                            bool symbolize, const char *strip_file_prefix,
66                            SymbolizeCallback symbolize_callback ) {
67  MemoryMappingLayout proc_maps;
68  InternalScopedBuffer<char> buff(GetPageSizeCached() * 2);
69  InternalScopedBuffer<AddressInfo> addr_frames(64);
70  uptr frame_num = 0;
71  for (uptr i = 0; i < size && addr[i]; i++) {
72    uptr pc = patch_pc(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
123uptr StackTrace::GetCurrentPc() {
124  return GET_CALLER_PC();
125}
126
127void 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;
133  while (frame >= prev_frame &&
134         frame < (uhwptr *)stack_top - 2 &&
135         frame > (uhwptr *)stack_bottom &&
136         size < max_size) {
137    uhwptr pc1 = frame[1];
138    if (pc1 != pc) {
139      trace[size++] = (uptr) pc1;
140    }
141    prev_frame = frame;
142    frame = (uhwptr *)frame[0];
143  }
144}
145
146void StackTrace::PopStackFrames(uptr count) {
147  CHECK(size >= count);
148  size -= count;
149  for (uptr i = 0; i < size; i++) {
150    trace[i] = trace[i + count];
151  }
152}
153
154// On 32-bits we don't compress stack traces.
155// On 64-bits we compress stack traces: if a given pc differes slightly from
156// the previous one, we record a 31-bit offset instead of the full pc.
157SANITIZER_INTERFACE_ATTRIBUTE
158uptr StackTrace::CompressStack(StackTrace *stack, u32 *compressed, uptr size) {
159#if SANITIZER_WORDSIZE == 32
160  // Don't compress, just copy.
161  uptr res = 0;
162  for (uptr i = 0; i < stack->size && i < size; i++) {
163    compressed[i] = stack->trace[i];
164    res++;
165  }
166  if (stack->size < size)
167    compressed[stack->size] = 0;
168#else  // 64 bits, compress.
169  uptr prev_pc = 0;
170  const uptr kMaxOffset = (1ULL << 30) - 1;
171  uptr c_index = 0;
172  uptr res = 0;
173  for (uptr i = 0, n = stack->size; i < n; i++) {
174    uptr pc = stack->trace[i];
175    if (!pc) break;
176    if ((s64)pc < 0) break;
177    // Printf("C pc[%zu] %zx\n", i, pc);
178    if (prev_pc - pc < kMaxOffset || pc - prev_pc < kMaxOffset) {
179      uptr offset = (s64)(pc - prev_pc);
180      offset |= (1U << 31);
181      if (c_index >= size) break;
182      // Printf("C co[%zu] offset %zx\n", i, offset);
183      compressed[c_index++] = offset;
184    } else {
185      uptr hi = pc >> 32;
186      uptr lo = (pc << 32) >> 32;
187      CHECK_EQ((hi & (1 << 31)), 0);
188      if (c_index + 1 >= size) break;
189      // Printf("C co[%zu] hi/lo: %zx %zx\n", c_index, hi, lo);
190      compressed[c_index++] = hi;
191      compressed[c_index++] = lo;
192    }
193    res++;
194    prev_pc = pc;
195  }
196  if (c_index < size)
197    compressed[c_index] = 0;
198  if (c_index + 1 < size)
199    compressed[c_index + 1] = 0;
200#endif  // SANITIZER_WORDSIZE
201
202  // debug-only code
203#if 0
204  StackTrace check_stack;
205  UncompressStack(&check_stack, compressed, size);
206  if (res < check_stack.size) {
207    Printf("res %zu check_stack.size %zu; c_size %zu\n", res,
208           check_stack.size, size);
209  }
210  // |res| may be greater than check_stack.size, because
211  // UncompressStack(CompressStack(stack)) eliminates the 0x0 frames.
212  CHECK(res >= check_stack.size);
213  CHECK_EQ(0, REAL(memcmp)(check_stack.trace, stack->trace,
214                          check_stack.size * sizeof(uptr)));
215#endif
216
217  return res;
218}
219
220SANITIZER_INTERFACE_ATTRIBUTE
221void StackTrace::UncompressStack(StackTrace *stack,
222                                 u32 *compressed, uptr size) {
223#if SANITIZER_WORDSIZE == 32
224  // Don't uncompress, just copy.
225  stack->size = 0;
226  for (uptr i = 0; i < size && i < kStackTraceMax; i++) {
227    if (!compressed[i]) break;
228    stack->size++;
229    stack->trace[i] = compressed[i];
230  }
231#else  // 64 bits, uncompress
232  uptr prev_pc = 0;
233  stack->size = 0;
234  for (uptr i = 0; i < size && stack->size < kStackTraceMax; i++) {
235    u32 x = compressed[i];
236    uptr pc = 0;
237    if (x & (1U << 31)) {
238      // Printf("U co[%zu] offset: %x\n", i, x);
239      // this is an offset
240      s32 offset = x;
241      offset = (offset << 1) >> 1;  // remove the 31-byte and sign-extend.
242      pc = prev_pc + offset;
243      CHECK(pc);
244    } else {
245      // CHECK(i + 1 < size);
246      if (i + 1 >= size) break;
247      uptr hi = x;
248      uptr lo = compressed[i+1];
249      // Printf("U co[%zu] hi/lo: %zx %zx\n", i, hi, lo);
250      i++;
251      pc = (hi << 32) | lo;
252      if (!pc) break;
253    }
254    // Printf("U pc[%zu] %zx\n", stack->size, pc);
255    stack->trace[stack->size++] = pc;
256    prev_pc = pc;
257  }
258#endif  // SANITIZER_WORDSIZE
259}
260
261}  // namespace __sanitizer
262