asan_stack.cc revision cb8c4dce691097718d5af41b36899b72ef4b1d84 
1//===-- asan_stack.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 a part of AddressSanitizer, an address sanity checker.
11//
12// Code for ASan stack trace.
13//===----------------------------------------------------------------------===//
14#include "asan_interceptors.h"
15#include "asan_lock.h"
16#include "asan_stack.h"
17#include "asan_thread.h"
18#include "asan_thread_registry.h"
19#include "sanitizer_common/sanitizer_procmaps.h"
20#include "sanitizer_common/sanitizer_symbolizer.h"
21
22#ifdef ASAN_USE_EXTERNAL_SYMBOLIZER
23extern bool
24ASAN_USE_EXTERNAL_SYMBOLIZER(const void *pc, char *out, int out_size);
25#endif
26
27namespace __asan {
28
29// ----------------------- AsanStackTrace ----------------------------- {{{1
30#if defined(ASAN_USE_EXTERNAL_SYMBOLIZER)
31void AsanStackTrace::PrintStack(uptr *addr, uptr size) {
32  for (uptr i = 0; i < size && addr[i]; i++) {
33    uptr pc = addr[i];
34    char buff[4096];
35    ASAN_USE_EXTERNAL_SYMBOLIZER((void*)pc, buff, sizeof(buff));
36    AsanPrintf("  #%zu 0x%zx %s\n", i, pc, buff);
37  }
38}
39
40#else  // ASAN_USE_EXTERNAL_SYMBOLIZER
41void AsanStackTrace::PrintStack(uptr *addr, uptr size) {
42  ProcessMaps proc_maps;
43  uptr frame_num = 0;
44  for (uptr i = 0; i < size && addr[i]; i++) {
45    uptr pc = addr[i];
46    AddressInfo addr_frames[64];
47    uptr addr_frames_num = 0;
48    if (flags()->symbolize) {
49      bool last_frame = (i == size - 1) || !addr[i + 1];
50      addr_frames_num = SymbolizeCode(pc - !last_frame, addr_frames,
51                                      ASAN_ARRAY_SIZE(addr_frames));
52    }
53    if (addr_frames_num > 0) {
54      for (uptr j = 0; j < addr_frames_num; j++) {
55        AddressInfo &info = addr_frames[j];
56        AsanPrintf("    #%zu 0x%zx", frame_num, pc);
57        if (info.function) {
58          AsanPrintf(" in %s", info.function);
59        }
60        if (info.file) {
61          AsanPrintf(" %s:%d:%d", info.file, info.line, info.column);
62        } else if (info.module) {
63          AsanPrintf(" (%s+0x%zx)", info.module, info.module_offset);
64        }
65        AsanPrintf("\n");
66        info.Clear();
67        frame_num++;
68      }
69    } else {
70      uptr offset;
71      char filename[4096];
72      if (proc_maps.GetObjectNameAndOffset(pc, &offset,
73                                           filename, sizeof(filename))) {
74        AsanPrintf("    #%zu 0x%zx (%s+0x%zx)\n", frame_num, pc, filename,
75                                                  offset);
76      } else {
77        AsanPrintf("    #%zu 0x%zx\n", frame_num, pc);
78      }
79      frame_num++;
80    }
81  }
82}
83#endif  // ASAN_USE_EXTERNAL_SYMBOLIZER
84
85uptr AsanStackTrace::GetCurrentPc() {
86  return GET_CALLER_PC();
87}
88
89void AsanStackTrace::FastUnwindStack(uptr pc, uptr bp) {
90  CHECK(size == 0 && trace[0] == pc);
91  size = 1;
92  if (!asan_inited) return;
93  AsanThread *t = asanThreadRegistry().GetCurrent();
94  if (!t) return;
95  uptr *frame = (uptr*)bp;
96  uptr *prev_frame = frame;
97  uptr *top = (uptr*)t->stack_top();
98  uptr *bottom = (uptr*)t->stack_bottom();
99  while (frame >= prev_frame &&
100         frame < top - 2 &&
101         frame > bottom &&
102         size < max_size) {
103    uptr pc1 = frame[1];
104    if (pc1 != pc) {
105      trace[size++] = pc1;
106    }
107    prev_frame = frame;
108    frame = (uptr*)frame[0];
109  }
110}
111
112// On 32-bits we don't compress stack traces.
113// On 64-bits we compress stack traces: if a given pc differes slightly from
114// the previous one, we record a 31-bit offset instead of the full pc.
115uptr AsanStackTrace::CompressStack(AsanStackTrace *stack,
116                                   u32 *compressed, uptr size) {
117#if __WORDSIZE == 32
118  // Don't compress, just copy.
119  uptr res = 0;
120  for (uptr i = 0; i < stack->size && i < size; i++) {
121    compressed[i] = stack->trace[i];
122    res++;
123  }
124  if (stack->size < size)
125    compressed[stack->size] = 0;
126#else  // 64 bits, compress.
127  uptr prev_pc = 0;
128  const uptr kMaxOffset = (1ULL << 30) - 1;
129  uptr c_index = 0;
130  uptr res = 0;
131  for (uptr i = 0, n = stack->size; i < n; i++) {
132    uptr pc = stack->trace[i];
133    if (!pc) break;
134    if ((s64)pc < 0) break;
135    // Printf("C pc[%zu] %zx\n", i, pc);
136    if (prev_pc - pc < kMaxOffset || pc - prev_pc < kMaxOffset) {
137      uptr offset = (s64)(pc - prev_pc);
138      offset |= (1U << 31);
139      if (c_index >= size) break;
140      // Printf("C co[%zu] offset %zx\n", i, offset);
141      compressed[c_index++] = offset;
142    } else {
143      uptr hi = pc >> 32;
144      uptr lo = (pc << 32) >> 32;
145      CHECK((hi & (1 << 31)) == 0);
146      if (c_index + 1 >= size) break;
147      // Printf("C co[%zu] hi/lo: %zx %zx\n", c_index, hi, lo);
148      compressed[c_index++] = hi;
149      compressed[c_index++] = lo;
150    }
151    res++;
152    prev_pc = pc;
153  }
154  if (c_index < size)
155    compressed[c_index] = 0;
156  if (c_index + 1 < size)
157    compressed[c_index + 1] = 0;
158#endif  // __WORDSIZE
159
160  // debug-only code
161#if 0
162  AsanStackTrace check_stack;
163  UncompressStack(&check_stack, compressed, size);
164  if (res < check_stack.size) {
165    Printf("res %zu check_stack.size %zu; c_size %zu\n", res,
166           check_stack.size, size);
167  }
168  // |res| may be greater than check_stack.size, because
169  // UncompressStack(CompressStack(stack)) eliminates the 0x0 frames.
170  CHECK(res >= check_stack.size);
171  CHECK(0 == REAL(memcmp)(check_stack.trace, stack->trace,
172                          check_stack.size * sizeof(uptr)));
173#endif
174
175  return res;
176}
177
178void AsanStackTrace::UncompressStack(AsanStackTrace *stack,
179                                     u32 *compressed, uptr size) {
180#if __WORDSIZE == 32
181  // Don't uncompress, just copy.
182  stack->size = 0;
183  for (uptr i = 0; i < size && i < kStackTraceMax; i++) {
184    if (!compressed[i]) break;
185    stack->size++;
186    stack->trace[i] = compressed[i];
187  }
188#else  // 64 bits, uncompress
189  uptr prev_pc = 0;
190  stack->size = 0;
191  for (uptr i = 0; i < size && stack->size < kStackTraceMax; i++) {
192    u32 x = compressed[i];
193    uptr pc = 0;
194    if (x & (1U << 31)) {
195      // Printf("U co[%zu] offset: %x\n", i, x);
196      // this is an offset
197      s32 offset = x;
198      offset = (offset << 1) >> 1;  // remove the 31-byte and sign-extend.
199      pc = prev_pc + offset;
200      CHECK(pc);
201    } else {
202      // CHECK(i + 1 < size);
203      if (i + 1 >= size) break;
204      uptr hi = x;
205      uptr lo = compressed[i+1];
206      // Printf("U co[%zu] hi/lo: %zx %zx\n", i, hi, lo);
207      i++;
208      pc = (hi << 32) | lo;
209      if (!pc) break;
210    }
211    // Printf("U pc[%zu] %zx\n", stack->size, pc);
212    stack->trace[stack->size++] = pc;
213    prev_pc = pc;
214  }
215#endif  // __WORDSIZE
216}
217
218}  // namespace __asan
219