sanitizer_stacktrace.cc revision ae894455254b9a15b6f11df7c2362f5f45586862 
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 {
20const char *StripPathPrefix(const char *filepath,
21                            const char *strip_file_prefix) {
22  if (filepath == 0) return 0;
23  const char *prefix_beg = internal_strstr(filepath, strip_file_prefix);
24  if (prefix_beg)
25    return prefix_beg + internal_strlen(strip_file_prefix);
26  return filepath;
27}
28
29// ----------------------- StackTrace ----------------------------- {{{1
30uptr StackTrace::GetPreviousInstructionPc(uptr pc) {
31#ifdef __arm__
32  // Cancel Thumb bit.
33  pc = pc & (~1);
34#endif
35#if defined(__powerpc__) || defined(__powerpc64__)
36  // PCs are always 4 byte aligned.
37  return pc - 4;
38#elif defined(__sparc__)
39  return pc - 8;
40#else
41  return pc - 1;
42#endif
43}
44
45static void PrintStackFramePrefix(uptr frame_num, uptr pc) {
46  Printf("    #%zu 0x%zx", frame_num, pc);
47}
48
49static void PrintSourceLocation(const char *file, int line, int column,
50                                const char *strip_file_prefix) {
51  CHECK(file);
52  Printf(" %s", StripPathPrefix(file, strip_file_prefix));
53  if (line > 0) {
54    Printf(":%d", line);
55    if (column > 0)
56      Printf(":%d", column);
57  }
58}
59
60static void PrintModuleAndOffset(const char *module, uptr offset,
61                                 const char *strip_file_prefix) {
62  Printf(" (%s+0x%zx)", StripPathPrefix(module, strip_file_prefix), offset);
63}
64
65void StackTrace::PrintStack(const uptr *addr, uptr size,
66                            bool symbolize, const char *strip_file_prefix,
67                            SymbolizeCallback symbolize_callback ) {
68  MemoryMappingLayout proc_maps(/*cache_enabled*/true);
69  InternalScopedBuffer<char> buff(GetPageSizeCached() * 2);
70  InternalScopedBuffer<AddressInfo> addr_frames(64);
71  uptr frame_num = 0;
72  for (uptr i = 0; i < size && addr[i]; i++) {
73    // PCs in stack traces are actually the return addresses, that is,
74    // addresses of the next instructions after the call.
75    uptr pc = GetPreviousInstructionPc(addr[i]);
76    uptr addr_frames_num = 0;  // The number of stack frames for current
77                               // instruction address.
78    if (symbolize_callback) {
79      if (symbolize_callback((void*)pc, buff.data(), buff.size())) {
80        addr_frames_num = 1;
81        PrintStackFramePrefix(frame_num, pc);
82        // We can't know anything about the string returned by external
83        // symbolizer, but if it starts with filename, try to strip path prefix
84        // from it.
85        Printf(" %s\n", StripPathPrefix(buff.data(), strip_file_prefix));
86        frame_num++;
87      }
88    }
89    if (symbolize && addr_frames_num == 0 && &SymbolizeCode) {
90      // Use our own (online) symbolizer, if necessary.
91      addr_frames_num = SymbolizeCode(pc, addr_frames.data(),
92                                      addr_frames.size());
93      for (uptr j = 0; j < addr_frames_num; j++) {
94        AddressInfo &info = addr_frames[j];
95        PrintStackFramePrefix(frame_num, pc);
96        if (info.function) {
97          Printf(" in %s", info.function);
98        }
99        if (info.file) {
100          PrintSourceLocation(info.file, info.line, info.column,
101                              strip_file_prefix);
102        } else if (info.module) {
103          PrintModuleAndOffset(info.module, info.module_offset,
104                               strip_file_prefix);
105        }
106        Printf("\n");
107        info.Clear();
108        frame_num++;
109      }
110    }
111    if (addr_frames_num == 0) {
112      // If online symbolization failed, try to output at least module and
113      // offset for instruction.
114      PrintStackFramePrefix(frame_num, pc);
115      uptr offset;
116      if (proc_maps.GetObjectNameAndOffset(pc, &offset,
117                                           buff.data(), buff.size(),
118                                           /* protection */0)) {
119        PrintModuleAndOffset(buff.data(), offset, strip_file_prefix);
120      }
121      Printf("\n");
122      frame_num++;
123    }
124  }
125}
126
127uptr StackTrace::GetCurrentPc() {
128  return GET_CALLER_PC();
129}
130
131void StackTrace::FastUnwindStack(uptr pc, uptr bp,
132                                 uptr stack_top, uptr stack_bottom) {
133  CHECK(size == 0 && trace[0] == pc);
134  size = 1;
135  uhwptr *frame = (uhwptr *)bp;
136  uhwptr *prev_frame = frame - 1;
137  if (stack_top < 4096) return;  // Sanity check for stack top.
138  // Avoid infinite loop when frame == frame[0] by using frame > prev_frame.
139  while (frame > prev_frame &&
140         frame < (uhwptr *)stack_top - 2 &&
141         frame > (uhwptr *)stack_bottom &&
142         IsAligned((uptr)frame, sizeof(*frame)) &&
143         size < max_size) {
144    uhwptr pc1 = frame[1];
145    if (pc1 != pc) {
146      trace[size++] = (uptr) pc1;
147    }
148    prev_frame = frame;
149    frame = (uhwptr *)frame[0];
150  }
151}
152
153void StackTrace::PopStackFrames(uptr count) {
154  CHECK(size >= count);
155  size -= count;
156  for (uptr i = 0; i < size; i++) {
157    trace[i] = trace[i + count];
158  }
159}
160
161// On 32-bits we don't compress stack traces.
162// On 64-bits we compress stack traces: if a given pc differes slightly from
163// the previous one, we record a 31-bit offset instead of the full pc.
164SANITIZER_INTERFACE_ATTRIBUTE
165uptr StackTrace::CompressStack(StackTrace *stack, u32 *compressed, uptr size) {
166#if SANITIZER_WORDSIZE == 32
167  // Don't compress, just copy.
168  uptr res = 0;
169  for (uptr i = 0; i < stack->size && i < size; i++) {
170    compressed[i] = stack->trace[i];
171    res++;
172  }
173  if (stack->size < size)
174    compressed[stack->size] = 0;
175#else  // 64 bits, compress.
176  uptr prev_pc = 0;
177  const uptr kMaxOffset = (1ULL << 30) - 1;
178  uptr c_index = 0;
179  uptr res = 0;
180  for (uptr i = 0, n = stack->size; i < n; i++) {
181    uptr pc = stack->trace[i];
182    if (!pc) break;
183    if ((s64)pc < 0) break;
184    // Printf("C pc[%zu] %zx\n", i, pc);
185    if (prev_pc - pc < kMaxOffset || pc - prev_pc < kMaxOffset) {
186      uptr offset = (s64)(pc - prev_pc);
187      offset |= (1U << 31);
188      if (c_index >= size) break;
189      // Printf("C co[%zu] offset %zx\n", i, offset);
190      compressed[c_index++] = offset;
191    } else {
192      uptr hi = pc >> 32;
193      uptr lo = (pc << 32) >> 32;
194      CHECK_EQ((hi & (1 << 31)), 0);
195      if (c_index + 1 >= size) break;
196      // Printf("C co[%zu] hi/lo: %zx %zx\n", c_index, hi, lo);
197      compressed[c_index++] = hi;
198      compressed[c_index++] = lo;
199    }
200    res++;
201    prev_pc = pc;
202  }
203  if (c_index < size)
204    compressed[c_index] = 0;
205  if (c_index + 1 < size)
206    compressed[c_index + 1] = 0;
207#endif  // SANITIZER_WORDSIZE
208
209  // debug-only code
210#if 0
211  StackTrace check_stack;
212  UncompressStack(&check_stack, compressed, size);
213  if (res < check_stack.size) {
214    Printf("res %zu check_stack.size %zu; c_size %zu\n", res,
215           check_stack.size, size);
216  }
217  // |res| may be greater than check_stack.size, because
218  // UncompressStack(CompressStack(stack)) eliminates the 0x0 frames.
219  CHECK(res >= check_stack.size);
220  CHECK_EQ(0, REAL(memcmp)(check_stack.trace, stack->trace,
221                          check_stack.size * sizeof(uptr)));
222#endif
223
224  return res;
225}
226
227SANITIZER_INTERFACE_ATTRIBUTE
228void StackTrace::UncompressStack(StackTrace *stack,
229                                 u32 *compressed, uptr size) {
230#if SANITIZER_WORDSIZE == 32
231  // Don't uncompress, just copy.
232  stack->size = 0;
233  for (uptr i = 0; i < size && i < kStackTraceMax; i++) {
234    if (!compressed[i]) break;
235    stack->size++;
236    stack->trace[i] = compressed[i];
237  }
238#else  // 64 bits, uncompress
239  uptr prev_pc = 0;
240  stack->size = 0;
241  for (uptr i = 0; i < size && stack->size < kStackTraceMax; i++) {
242    u32 x = compressed[i];
243    uptr pc = 0;
244    if (x & (1U << 31)) {
245      // Printf("U co[%zu] offset: %x\n", i, x);
246      // this is an offset
247      s32 offset = x;
248      offset = (offset << 1) >> 1;  // remove the 31-byte and sign-extend.
249      pc = prev_pc + offset;
250      CHECK(pc);
251    } else {
252      // CHECK(i + 1 < size);
253      if (i + 1 >= size) break;
254      uptr hi = x;
255      uptr lo = compressed[i+1];
256      // Printf("U co[%zu] hi/lo: %zx %zx\n", i, hi, lo);
257      i++;
258      pc = (hi << 32) | lo;
259      if (!pc) break;
260    }
261    // Printf("U pc[%zu] %zx\n", stack->size, pc);
262    stack->trace[stack->size++] = pc;
263    prev_pc = pc;
264  }
265#endif  // SANITIZER_WORDSIZE
266}
267
268}  // namespace __sanitizer
269