asan_stack.cc revision 238901 
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// PCs in stack traces are actually the return addresses, that is,
31// addresses of the next instructions after the call. That's why we
32// decrement them.
33static uptr patch_pc(uptr pc) {
34#ifdef __arm__
35  // Cancel Thumb bit.
36  pc = pc & (~1);
37#endif
38  return pc - 1;
39}
40
41#if defined(ASAN_USE_EXTERNAL_SYMBOLIZER)
42void AsanStackTrace::PrintStack(uptr *addr, uptr size) {
43  for (uptr i = 0; i < size && addr[i]; i++) {
44    uptr pc = addr[i];
45    if (i < size - 1 && addr[i + 1])
46      pc = patch_pc(pc);
47    char buff[4096];
48    ASAN_USE_EXTERNAL_SYMBOLIZER((void*)pc, buff, sizeof(buff));
49    AsanPrintf("  #%zu 0x%zx %s\n", i, pc, buff);
50  }
51}
52
53#else  // ASAN_USE_EXTERNAL_SYMBOLIZER
54void AsanStackTrace::PrintStack(uptr *addr, uptr size) {
55  ProcessMaps proc_maps;
56  uptr frame_num = 0;
57  for (uptr i = 0; i < size && addr[i]; i++) {
58    uptr pc = addr[i];
59    if (i < size - 1 && addr[i + 1])
60      pc = patch_pc(pc);
61    AddressInfo addr_frames[64];
62    uptr addr_frames_num = 0;
63    if (flags()->symbolize) {
64      addr_frames_num = SymbolizeCode(pc, addr_frames,
65                                      ASAN_ARRAY_SIZE(addr_frames));
66    }
67    if (addr_frames_num > 0) {
68      for (uptr j = 0; j < addr_frames_num; j++) {
69        AddressInfo &info = addr_frames[j];
70        AsanPrintf("    #%zu 0x%zx", frame_num, pc);
71        if (info.function) {
72          AsanPrintf(" in %s", info.function);
73        }
74        if (info.file) {
75          AsanPrintf(" %s:%d:%d", info.file, info.line, info.column);
76        } else if (info.module) {
77          AsanPrintf(" (%s+0x%zx)", info.module, info.module_offset);
78        }
79        AsanPrintf("\n");
80        info.Clear();
81        frame_num++;
82      }
83    } else {
84      uptr offset;
85      char filename[4096];
86      if (proc_maps.GetObjectNameAndOffset(pc, &offset,
87                                           filename, sizeof(filename))) {
88        AsanPrintf("    #%zu 0x%zx (%s+0x%zx)\n", frame_num, pc, filename,
89                                                  offset);
90      } else {
91        AsanPrintf("    #%zu 0x%zx\n", frame_num, pc);
92      }
93      frame_num++;
94    }
95  }
96}
97#endif  // ASAN_USE_EXTERNAL_SYMBOLIZER
98
99uptr AsanStackTrace::GetCurrentPc() {
100  return GET_CALLER_PC();
101}
102
103void AsanStackTrace::FastUnwindStack(uptr pc, uptr bp) {
104  CHECK(size == 0 && trace[0] == pc);
105  size = 1;
106  if (!asan_inited) return;
107  AsanThread *t = asanThreadRegistry().GetCurrent();
108  if (!t) return;
109  uptr *frame = (uptr*)bp;
110  uptr *prev_frame = frame;
111  uptr *top = (uptr*)t->stack_top();
112  uptr *bottom = (uptr*)t->stack_bottom();
113  while (frame >= prev_frame &&
114         frame < top - 2 &&
115         frame > bottom &&
116         size < max_size) {
117    uptr pc1 = frame[1];
118    if (pc1 != pc) {
119      trace[size++] = pc1;
120    }
121    prev_frame = frame;
122    frame = (uptr*)frame[0];
123  }
124}
125
126// On 32-bits we don't compress stack traces.
127// On 64-bits we compress stack traces: if a given pc differes slightly from
128// the previous one, we record a 31-bit offset instead of the full pc.
129uptr AsanStackTrace::CompressStack(AsanStackTrace *stack,
130                                   u32 *compressed, uptr size) {
131#if __WORDSIZE == 32
132  // Don't compress, just copy.
133  uptr res = 0;
134  for (uptr i = 0; i < stack->size && i < size; i++) {
135    compressed[i] = stack->trace[i];
136    res++;
137  }
138  if (stack->size < size)
139    compressed[stack->size] = 0;
140#else  // 64 bits, compress.
141  uptr prev_pc = 0;
142  const uptr kMaxOffset = (1ULL << 30) - 1;
143  uptr c_index = 0;
144  uptr res = 0;
145  for (uptr i = 0, n = stack->size; i < n; i++) {
146    uptr pc = stack->trace[i];
147    if (!pc) break;
148    if ((s64)pc < 0) break;
149    // Printf("C pc[%zu] %zx\n", i, pc);
150    if (prev_pc - pc < kMaxOffset || pc - prev_pc < kMaxOffset) {
151      uptr offset = (s64)(pc - prev_pc);
152      offset |= (1U << 31);
153      if (c_index >= size) break;
154      // Printf("C co[%zu] offset %zx\n", i, offset);
155      compressed[c_index++] = offset;
156    } else {
157      uptr hi = pc >> 32;
158      uptr lo = (pc << 32) >> 32;
159      CHECK((hi & (1 << 31)) == 0);
160      if (c_index + 1 >= size) break;
161      // Printf("C co[%zu] hi/lo: %zx %zx\n", c_index, hi, lo);
162      compressed[c_index++] = hi;
163      compressed[c_index++] = lo;
164    }
165    res++;
166    prev_pc = pc;
167  }
168  if (c_index < size)
169    compressed[c_index] = 0;
170  if (c_index + 1 < size)
171    compressed[c_index + 1] = 0;
172#endif  // __WORDSIZE
173
174  // debug-only code
175#if 0
176  AsanStackTrace check_stack;
177  UncompressStack(&check_stack, compressed, size);
178  if (res < check_stack.size) {
179    Printf("res %zu check_stack.size %zu; c_size %zu\n", res,
180           check_stack.size, size);
181  }
182  // |res| may be greater than check_stack.size, because
183  // UncompressStack(CompressStack(stack)) eliminates the 0x0 frames.
184  CHECK(res >= check_stack.size);
185  CHECK(0 == REAL(memcmp)(check_stack.trace, stack->trace,
186                          check_stack.size * sizeof(uptr)));
187#endif
188
189  return res;
190}
191
192void AsanStackTrace::UncompressStack(AsanStackTrace *stack,
193                                     u32 *compressed, uptr size) {
194#if __WORDSIZE == 32
195  // Don't uncompress, just copy.
196  stack->size = 0;
197  for (uptr i = 0; i < size && i < kStackTraceMax; i++) {
198    if (!compressed[i]) break;
199    stack->size++;
200    stack->trace[i] = compressed[i];
201  }
202#else  // 64 bits, uncompress
203  uptr prev_pc = 0;
204  stack->size = 0;
205  for (uptr i = 0; i < size && stack->size < kStackTraceMax; i++) {
206    u32 x = compressed[i];
207    uptr pc = 0;
208    if (x & (1U << 31)) {
209      // Printf("U co[%zu] offset: %x\n", i, x);
210      // this is an offset
211      s32 offset = x;
212      offset = (offset << 1) >> 1;  // remove the 31-byte and sign-extend.
213      pc = prev_pc + offset;
214      CHECK(pc);
215    } else {
216      // CHECK(i + 1 < size);
217      if (i + 1 >= size) break;
218      uptr hi = x;
219      uptr lo = compressed[i+1];
220      // Printf("U co[%zu] hi/lo: %zx %zx\n", i, hi, lo);
221      i++;
222      pc = (hi << 32) | lo;
223      if (!pc) break;
224    }
225    // Printf("U pc[%zu] %zx\n", stack->size, pc);
226    stack->trace[stack->size++] = pc;
227    prev_pc = pc;
228  }
229#endif  // __WORDSIZE
230}
231
232}  // namespace __asan
233