sanitizer_stacktrace.cc revision 7996a2e2a1c461743c9216f13429c04d75050230 
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_procmaps.h"
17#include "sanitizer_stacktrace.h"
18#include "sanitizer_symbolizer.h"
19
20namespace __sanitizer {
21
22uptr StackTrace::GetPreviousInstructionPc(uptr pc) {
23#ifdef __arm__
24  // Cancel Thumb bit.
25  pc = pc & (~1);
26#endif
27#if defined(__powerpc__) || defined(__powerpc64__)
28  // PCs are always 4 byte aligned.
29  return pc - 4;
30#elif defined(__sparc__)
31  return pc - 8;
32#else
33  return pc - 1;
34#endif
35}
36
37static void PrintStackFramePrefix(uptr frame_num, uptr pc) {
38  Printf("    #%zu 0x%zx", frame_num, pc);
39}
40
41void StackTrace::PrintStack(const uptr *addr, uptr size,
42                            SymbolizeCallback symbolize_callback) {
43  MemoryMappingLayout proc_maps(/*cache_enabled*/true);
44  InternalScopedBuffer<char> buff(GetPageSizeCached() * 2);
45  InternalScopedBuffer<AddressInfo> addr_frames(64);
46  uptr frame_num = 0;
47  for (uptr i = 0; i < size && addr[i]; i++) {
48    // PCs in stack traces are actually the return addresses, that is,
49    // addresses of the next instructions after the call.
50    uptr pc = GetPreviousInstructionPc(addr[i]);
51    uptr addr_frames_num = 0;  // The number of stack frames for current
52                               // instruction address.
53    if (symbolize_callback) {
54      if (symbolize_callback((void*)pc, buff.data(), buff.size())) {
55        addr_frames_num = 1;
56        PrintStackFramePrefix(frame_num, pc);
57        // We can't know anything about the string returned by external
58        // symbolizer, but if it starts with filename, try to strip path prefix
59        // from it.
60        Printf(" %s\n",
61               StripPathPrefix(buff.data(), common_flags()->strip_path_prefix));
62        frame_num++;
63      }
64    }
65    if (common_flags()->symbolize && addr_frames_num == 0) {
66      // Use our own (online) symbolizer, if necessary.
67      if (Symbolizer *sym = Symbolizer::GetOrNull())
68        addr_frames_num =
69            sym->SymbolizeCode(pc, addr_frames.data(), addr_frames.size());
70      for (uptr j = 0; j < addr_frames_num; j++) {
71        AddressInfo &info = addr_frames[j];
72        PrintStackFramePrefix(frame_num, pc);
73        if (info.function) {
74          Printf(" in %s", info.function);
75        }
76        if (info.file) {
77          Printf(" ");
78          PrintSourceLocation(info.file, info.line, info.column);
79        } else if (info.module) {
80          Printf(" ");
81          PrintModuleAndOffset(info.module, info.module_offset);
82        }
83        Printf("\n");
84        info.Clear();
85        frame_num++;
86      }
87    }
88    if (addr_frames_num == 0) {
89      // If online symbolization failed, try to output at least module and
90      // offset for instruction.
91      PrintStackFramePrefix(frame_num, pc);
92      uptr offset;
93      if (proc_maps.GetObjectNameAndOffset(pc, &offset,
94                                           buff.data(), buff.size(),
95                                           /* protection */0)) {
96        Printf(" ");
97        PrintModuleAndOffset(buff.data(), offset);
98      }
99      Printf("\n");
100      frame_num++;
101    }
102  }
103}
104
105uptr StackTrace::GetCurrentPc() {
106  return GET_CALLER_PC();
107}
108
109void StackTrace::FastUnwindStack(uptr pc, uptr bp,
110                                 uptr stack_top, uptr stack_bottom,
111                                 uptr max_depth) {
112  if (max_depth == 0) {
113    size = 0;
114    return;
115  }
116  trace[0] = pc;
117  size = 1;
118  uhwptr *frame = (uhwptr *)bp;
119  uhwptr *prev_frame = frame - 1;
120  if (stack_top < 4096) return;  // Sanity check for stack top.
121  // Avoid infinite loop when frame == frame[0] by using frame > prev_frame.
122  while (frame > prev_frame &&
123         frame < (uhwptr *)stack_top - 2 &&
124         frame > (uhwptr *)stack_bottom &&
125         IsAligned((uptr)frame, sizeof(*frame)) &&
126         size < max_depth) {
127    uhwptr pc1 = frame[1];
128    if (pc1 != pc) {
129      trace[size++] = (uptr) pc1;
130    }
131    prev_frame = frame;
132    frame = (uhwptr *)frame[0];
133  }
134}
135
136void StackTrace::PopStackFrames(uptr count) {
137  CHECK(size >= count);
138  size -= count;
139  for (uptr i = 0; i < size; i++) {
140    trace[i] = trace[i + count];
141  }
142}
143
144// On 32-bits we don't compress stack traces.
145// On 64-bits we compress stack traces: if a given pc differes slightly from
146// the previous one, we record a 31-bit offset instead of the full pc.
147uptr StackTrace::CompressStack(StackTrace *stack, u32 *compressed, uptr size) {
148#if SANITIZER_WORDSIZE == 32
149  // Don't compress, just copy.
150  uptr res = 0;
151  for (uptr i = 0; i < stack->size && i < size; i++) {
152    compressed[i] = stack->trace[i];
153    res++;
154  }
155  if (stack->size < size)
156    compressed[stack->size] = 0;
157#else  // 64 bits, compress.
158  uptr prev_pc = 0;
159  const uptr kMaxOffset = (1ULL << 30) - 1;
160  uptr c_index = 0;
161  uptr res = 0;
162  for (uptr i = 0, n = stack->size; i < n; i++) {
163    uptr pc = stack->trace[i];
164    if (!pc) break;
165    if ((s64)pc < 0) break;
166    // Printf("C pc[%zu] %zx\n", i, pc);
167    if (prev_pc - pc < kMaxOffset || pc - prev_pc < kMaxOffset) {
168      uptr offset = (s64)(pc - prev_pc);
169      offset |= (1U << 31);
170      if (c_index >= size) break;
171      // Printf("C co[%zu] offset %zx\n", i, offset);
172      compressed[c_index++] = offset;
173    } else {
174      uptr hi = pc >> 32;
175      uptr lo = (pc << 32) >> 32;
176      CHECK_EQ((hi & (1 << 31)), 0);
177      if (c_index + 1 >= size) break;
178      // Printf("C co[%zu] hi/lo: %zx %zx\n", c_index, hi, lo);
179      compressed[c_index++] = hi;
180      compressed[c_index++] = lo;
181    }
182    res++;
183    prev_pc = pc;
184  }
185  if (c_index < size)
186    compressed[c_index] = 0;
187  if (c_index + 1 < size)
188    compressed[c_index + 1] = 0;
189#endif  // SANITIZER_WORDSIZE
190
191  // debug-only code
192#if 0
193  StackTrace check_stack;
194  UncompressStack(&check_stack, compressed, size);
195  if (res < check_stack.size) {
196    Printf("res %zu check_stack.size %zu; c_size %zu\n", res,
197           check_stack.size, size);
198  }
199  // |res| may be greater than check_stack.size, because
200  // UncompressStack(CompressStack(stack)) eliminates the 0x0 frames.
201  CHECK(res >= check_stack.size);
202  CHECK_EQ(0, REAL(memcmp)(check_stack.trace, stack->trace,
203                          check_stack.size * sizeof(uptr)));
204#endif
205
206  return res;
207}
208
209void StackTrace::UncompressStack(StackTrace *stack,
210                                 u32 *compressed, uptr size) {
211#if SANITIZER_WORDSIZE == 32
212  // Don't uncompress, just copy.
213  stack->size = 0;
214  for (uptr i = 0; i < size && i < kStackTraceMax; i++) {
215    if (!compressed[i]) break;
216    stack->size++;
217    stack->trace[i] = compressed[i];
218  }
219#else  // 64 bits, uncompress
220  uptr prev_pc = 0;
221  stack->size = 0;
222  for (uptr i = 0; i < size && stack->size < kStackTraceMax; i++) {
223    u32 x = compressed[i];
224    uptr pc = 0;
225    if (x & (1U << 31)) {
226      // Printf("U co[%zu] offset: %x\n", i, x);
227      // this is an offset
228      s32 offset = x;
229      offset = (offset << 1) >> 1;  // remove the 31-byte and sign-extend.
230      pc = prev_pc + offset;
231      CHECK(pc);
232    } else {
233      // CHECK(i + 1 < size);
234      if (i + 1 >= size) break;
235      uptr hi = x;
236      uptr lo = compressed[i+1];
237      // Printf("U co[%zu] hi/lo: %zx %zx\n", i, hi, lo);
238      i++;
239      pc = (hi << 32) | lo;
240      if (!pc) break;
241    }
242    // Printf("U pc[%zu] %zx\n", stack->size, pc);
243    stack->trace[stack->size++] = pc;
244    prev_pc = pc;
245  }
246#endif  // SANITIZER_WORDSIZE
247}
248
249}  // namespace __sanitizer
250