sanitizer_stacktrace.cc revision 80175018541984bdcfe6a304bb189bd30592fa8a 
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_flags.h"
16#include "sanitizer_libc.h"
17#include "sanitizer_procmaps.h"
18#include "sanitizer_stacktrace.h"
19#include "sanitizer_symbolizer.h"
20
21namespace __sanitizer {
22
23uptr StackTrace::GetPreviousInstructionPc(uptr pc) {
24#ifdef __arm__
25  // Cancel Thumb bit.
26  pc = pc & (~1);
27#endif
28#if defined(__powerpc__) || defined(__powerpc64__)
29  // PCs are always 4 byte aligned.
30  return pc - 4;
31#elif defined(__sparc__)
32  return pc - 8;
33#else
34  return pc - 1;
35#endif
36}
37
38void StackTrace::CopyFrom(const uptr *src, uptr src_size) {
39  size = Min(src_size, kStackTraceMax);
40  internal_memcpy(trace, src, sizeof(trace[0]) * size);
41}
42
43static void PrintStackFramePrefix(uptr frame_num, uptr pc) {
44  Printf("    #%zu 0x%zx", frame_num, pc);
45}
46
47void StackTrace::PrintStack(const uptr *addr, uptr size, bool symbolize,
48                            SymbolizeCallback symbolize_callback) {
49  MemoryMappingLayout proc_maps(/*cache_enabled*/true);
50  InternalScopedBuffer<char> buff(GetPageSizeCached() * 2);
51  InternalScopedBuffer<AddressInfo> addr_frames(64);
52  uptr frame_num = 0;
53  for (uptr i = 0; i < size && addr[i]; i++) {
54    // PCs in stack traces are actually the return addresses, that is,
55    // addresses of the next instructions after the call.
56    uptr pc = GetPreviousInstructionPc(addr[i]);
57    uptr addr_frames_num = 0;  // The number of stack frames for current
58                               // instruction address.
59    if (symbolize_callback) {
60      if (symbolize_callback((void*)pc, buff.data(), buff.size())) {
61        addr_frames_num = 1;
62        PrintStackFramePrefix(frame_num, pc);
63        // We can't know anything about the string returned by external
64        // symbolizer, but if it starts with filename, try to strip path prefix
65        // from it.
66        Printf(" %s\n",
67               StripPathPrefix(buff.data(), common_flags()->strip_path_prefix));
68        frame_num++;
69      }
70    }
71    if (symbolize && addr_frames_num == 0 && &getSymbolizer) {
72      // Use our own (online) symbolizer, if necessary.
73      addr_frames_num = getSymbolizer()->SymbolizeCode(
74          pc, addr_frames.data(), addr_frames.size());
75      for (uptr j = 0; j < addr_frames_num; j++) {
76        AddressInfo &info = addr_frames[j];
77        PrintStackFramePrefix(frame_num, pc);
78        if (info.function) {
79          Printf(" in %s", info.function);
80        }
81        if (info.file) {
82          Printf(" ");
83          PrintSourceLocation(info.file, info.line, info.column);
84        } else if (info.module) {
85          Printf(" ");
86          PrintModuleAndOffset(info.module, info.module_offset);
87        }
88        Printf("\n");
89        info.Clear();
90        frame_num++;
91      }
92    }
93    if (addr_frames_num == 0) {
94      // If online symbolization failed, try to output at least module and
95      // offset for instruction.
96      PrintStackFramePrefix(frame_num, pc);
97      uptr offset;
98      if (proc_maps.GetObjectNameAndOffset(pc, &offset,
99                                           buff.data(), buff.size(),
100                                           /* protection */0)) {
101        Printf(" ");
102        PrintModuleAndOffset(buff.data(), offset);
103      }
104      Printf("\n");
105      frame_num++;
106    }
107  }
108}
109
110uptr StackTrace::GetCurrentPc() {
111  return GET_CALLER_PC();
112}
113
114void StackTrace::FastUnwindStack(uptr pc, uptr bp,
115                                 uptr stack_top, uptr stack_bottom,
116                                 uptr max_depth) {
117  max_size = max_depth;
118  if (max_size == 0) {
119    size = 0;
120    return;
121  }
122  trace[0] = pc;
123  size = 1;
124  uhwptr *frame = (uhwptr *)bp;
125  uhwptr *prev_frame = frame - 1;
126  if (stack_top < 4096) return;  // Sanity check for stack top.
127  // Avoid infinite loop when frame == frame[0] by using frame > prev_frame.
128  while (frame > prev_frame &&
129         frame < (uhwptr *)stack_top - 2 &&
130         frame > (uhwptr *)stack_bottom &&
131         IsAligned((uptr)frame, sizeof(*frame)) &&
132         size < max_size) {
133    uhwptr pc1 = frame[1];
134    if (pc1 != pc) {
135      trace[size++] = (uptr) pc1;
136    }
137    prev_frame = frame;
138    frame = (uhwptr *)frame[0];
139  }
140}
141
142void StackTrace::PopStackFrames(uptr count) {
143  CHECK(size >= count);
144  size -= count;
145  for (uptr i = 0; i < size; i++) {
146    trace[i] = trace[i + count];
147  }
148}
149
150// On 32-bits we don't compress stack traces.
151// On 64-bits we compress stack traces: if a given pc differes slightly from
152// the previous one, we record a 31-bit offset instead of the full pc.
153uptr StackTrace::CompressStack(StackTrace *stack, u32 *compressed, uptr size) {
154#if SANITIZER_WORDSIZE == 32
155  // Don't compress, just copy.
156  uptr res = 0;
157  for (uptr i = 0; i < stack->size && i < size; i++) {
158    compressed[i] = stack->trace[i];
159    res++;
160  }
161  if (stack->size < size)
162    compressed[stack->size] = 0;
163#else  // 64 bits, compress.
164  uptr prev_pc = 0;
165  const uptr kMaxOffset = (1ULL << 30) - 1;
166  uptr c_index = 0;
167  uptr res = 0;
168  for (uptr i = 0, n = stack->size; i < n; i++) {
169    uptr pc = stack->trace[i];
170    if (!pc) break;
171    if ((s64)pc < 0) break;
172    // Printf("C pc[%zu] %zx\n", i, pc);
173    if (prev_pc - pc < kMaxOffset || pc - prev_pc < kMaxOffset) {
174      uptr offset = (s64)(pc - prev_pc);
175      offset |= (1U << 31);
176      if (c_index >= size) break;
177      // Printf("C co[%zu] offset %zx\n", i, offset);
178      compressed[c_index++] = offset;
179    } else {
180      uptr hi = pc >> 32;
181      uptr lo = (pc << 32) >> 32;
182      CHECK_EQ((hi & (1 << 31)), 0);
183      if (c_index + 1 >= size) break;
184      // Printf("C co[%zu] hi/lo: %zx %zx\n", c_index, hi, lo);
185      compressed[c_index++] = hi;
186      compressed[c_index++] = lo;
187    }
188    res++;
189    prev_pc = pc;
190  }
191  if (c_index < size)
192    compressed[c_index] = 0;
193  if (c_index + 1 < size)
194    compressed[c_index + 1] = 0;
195#endif  // SANITIZER_WORDSIZE
196
197  // debug-only code
198#if 0
199  StackTrace check_stack;
200  UncompressStack(&check_stack, compressed, size);
201  if (res < check_stack.size) {
202    Printf("res %zu check_stack.size %zu; c_size %zu\n", res,
203           check_stack.size, size);
204  }
205  // |res| may be greater than check_stack.size, because
206  // UncompressStack(CompressStack(stack)) eliminates the 0x0 frames.
207  CHECK(res >= check_stack.size);
208  CHECK_EQ(0, REAL(memcmp)(check_stack.trace, stack->trace,
209                          check_stack.size * sizeof(uptr)));
210#endif
211
212  return res;
213}
214
215void StackTrace::UncompressStack(StackTrace *stack,
216                                 u32 *compressed, uptr size) {
217#if SANITIZER_WORDSIZE == 32
218  // Don't uncompress, just copy.
219  stack->size = 0;
220  for (uptr i = 0; i < size && i < kStackTraceMax; i++) {
221    if (!compressed[i]) break;
222    stack->size++;
223    stack->trace[i] = compressed[i];
224  }
225#else  // 64 bits, uncompress
226  uptr prev_pc = 0;
227  stack->size = 0;
228  for (uptr i = 0; i < size && stack->size < kStackTraceMax; i++) {
229    u32 x = compressed[i];
230    uptr pc = 0;
231    if (x & (1U << 31)) {
232      // Printf("U co[%zu] offset: %x\n", i, x);
233      // this is an offset
234      s32 offset = x;
235      offset = (offset << 1) >> 1;  // remove the 31-byte and sign-extend.
236      pc = prev_pc + offset;
237      CHECK(pc);
238    } else {
239      // CHECK(i + 1 < size);
240      if (i + 1 >= size) break;
241      uptr hi = x;
242      uptr lo = compressed[i+1];
243      // Printf("U co[%zu] hi/lo: %zx %zx\n", i, hi, lo);
244      i++;
245      pc = (hi << 32) | lo;
246      if (!pc) break;
247    }
248    // Printf("U pc[%zu] %zx\n", stack->size, pc);
249    stack->trace[stack->size++] = pc;
250    prev_pc = pc;
251  }
252#endif  // SANITIZER_WORDSIZE
253}
254
255}  // namespace __sanitizer
256