asan_stack.cc revision c6f2223a8772262e5e682403f2d57f0b465a98fc 
1//===-- asan_stack.cc -------------------------------------------*- C++ -*-===//
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
20#include <string.h>
21
22#if ASAN_USE_SYSINFO == 1
23#include "sysinfo/sysinfo.h"
24#endif
25
26#ifdef ASAN_USE_EXTERNAL_SYMBOLIZER
27extern bool
28ASAN_USE_EXTERNAL_SYMBOLIZER(const void *pc, char *out, int out_size);
29#endif
30
31namespace __asan {
32
33// ----------------------- ProcSelfMaps ----------------------------- {{{1
34#if ASAN_USE_SYSINFO == 1
35class ProcSelfMaps {
36 public:
37  void Init() {
38    ScopedLock lock(&mu_);
39    if (map_size_ != 0) return;  // already inited
40    if (FLAG_v >= 2) {
41      Printf("ProcSelfMaps::Init()\n");
42    }
43    ProcMapsIterator it(0, &proc_self_maps_);   // 0 means "current pid"
44
45    uint64 start, end, offset;
46    int64 inode;
47    char *flags, *filename;
48    CHECK(map_size_ == 0);
49    while (it.Next(&start, &end, &flags, &offset, &inode, &filename)) {
50      CHECK(map_size_ < kMaxProcSelfMapsSize);
51      Mapping &mapping = memory_map[map_size_];
52      mapping.beg = start;
53      mapping.end = end;
54      mapping.offset = offset;
55      real_strncpy(mapping.name,
56                   filename, ASAN_ARRAY_SIZE(mapping.name));
57      mapping.name[ASAN_ARRAY_SIZE(mapping.name) - 1] = 0;
58      if (FLAG_v >= 2) {
59        Printf("[%ld] [%p,%p] off %p %s\n", map_size_,
60               mapping.beg, mapping.end, mapping.offset, mapping.name);
61      }
62      map_size_++;
63    }
64  }
65
66  void Print() {
67    Printf("%s\n", proc_self_maps_);
68  }
69
70  void PrintPc(uintptr_t pc, int idx) {
71    for (size_t i = 0; i < map_size_; i++) {
72      Mapping &m = memory_map[i];
73      if (pc >= m.beg && pc < m.end) {
74        uintptr_t offset = pc - m.beg;
75        if (i == 0) offset = pc;
76        Printf("    #%d 0x%lx (%s+0x%lx)\n", idx, pc, m.name, offset);
77        return;
78      }
79    }
80    Printf("  #%d 0x%lx\n", idx, pc);
81  }
82
83 private:
84  void copy_until_new_line(const char *str, char *dest, size_t max_size) {
85    size_t i = 0;
86    for (; str[i] && str[i] != '\n' && i < max_size - 1; i++) {
87      dest[i] = str[i];
88    }
89    dest[i] = 0;
90  }
91
92
93  struct Mapping {
94    uintptr_t beg, end, offset;
95    char name[1000];
96  };
97  static const size_t kMaxNumMapEntries = 4096;
98  static const size_t kMaxProcSelfMapsSize = 1 << 20;
99  ProcMapsIterator::Buffer proc_self_maps_;
100  size_t map_size_;
101  Mapping memory_map[kMaxNumMapEntries];
102
103  static AsanLock mu_;
104};
105
106static ProcSelfMaps proc_self_maps;
107AsanLock ProcSelfMaps::mu_(LINKER_INITIALIZED);
108
109
110void AsanStackTrace::PrintStack(uintptr_t *addr, size_t size) {
111  proc_self_maps.Init();
112  for (size_t i = 0; i < size && addr[i]; i++) {
113    uintptr_t pc = addr[i];
114    // int line;
115    proc_self_maps.PrintPc(pc, i);
116    // Printf("  #%ld 0x%lx %s\n", i, pc, rtn.c_str());
117  }
118}
119#elif defined(ASAN_USE_EXTERNAL_SYMBOLIZER)
120void AsanStackTrace::PrintStack(uintptr_t *addr, size_t size) {
121  for (size_t i = 0; i < size && addr[i]; i++) {
122    uintptr_t pc = addr[i];
123    char buff[4096];
124    ASAN_USE_EXTERNAL_SYMBOLIZER((void*)pc, buff, sizeof(buff));
125    Printf("  #%ld 0x%lx %s\n", i, pc, buff);
126  }
127}
128
129#else  // ASAN_USE_SYSINFO
130void AsanStackTrace::PrintStack(uintptr_t *addr, size_t size) {
131  for (size_t i = 0; i < size && addr[i]; i++) {
132    uintptr_t pc = addr[i];
133    Printf("  #%ld 0x%lx\n", i, pc);
134  }
135}
136#endif  // ASAN_USE_SYSINFO
137
138#ifdef __arm__
139#define UNWIND_STOP _URC_END_OF_STACK
140#define UNWIND_CONTINUE _URC_OK
141#else
142#define UNWIND_STOP _URC_NORMAL_STOP
143#define UNWIND_CONTINUE _URC_NO_REASON
144#endif
145
146// ----------------------- AsanStackTrace ----------------------------- {{{1
147uintptr_t AsanStackTrace::GetCurrentPc() {
148  return GET_CALLER_PC();
149}
150
151void AsanStackTrace::FastUnwindStack(uintptr_t pc, uintptr_t bp) {
152  CHECK(size == 0 && trace[0] == pc);
153  size = 1;
154  if (!asan_inited) return;
155  AsanThread *t = asanThreadRegistry().GetCurrent();
156  if (!t) return;
157  uintptr_t *frame = (uintptr_t*)bp;
158  uintptr_t *prev_frame = frame;
159  uintptr_t *top = (uintptr_t*)t->stack_top();
160  uintptr_t *bottom = (uintptr_t*)t->stack_bottom();
161  while (frame >= prev_frame &&
162         frame < top &&
163         frame > bottom &&
164         size < max_size) {
165    uintptr_t pc1 = frame[1];
166    if (pc1 != pc) {
167      trace[size++] = pc1;
168    }
169    prev_frame = frame;
170    frame = (uintptr_t*)frame[0];
171  }
172}
173
174// On 32-bits we don't compress stack traces.
175// On 64-bits we compress stack traces: if a given pc differes slightly from
176// the previous one, we record a 31-bit offset instead of the full pc.
177size_t AsanStackTrace::CompressStack(AsanStackTrace *stack,
178                                   uint32_t *compressed, size_t size) {
179#if __WORDSIZE == 32
180  // Don't compress, just copy.
181  size_t res = 0;
182  for (size_t i = 0; i < stack->size && i < size; i++) {
183    compressed[i] = stack->trace[i];
184    res++;
185  }
186  for (size_t i = stack->size; i < size; i++) {
187    compressed[i] = 0;
188  }
189#else  // 64 bits, compress.
190  uintptr_t prev_pc = 0;
191  const uintptr_t kMaxOffset = (1ULL << 30) - 1;
192  uintptr_t c_index = 0;
193  size_t res = 0;
194  for (size_t i = 0, n = stack->size; i < n; i++) {
195    uintptr_t pc = stack->trace[i];
196    if (!pc) break;
197    if ((int64_t)pc < 0) break;
198    // Printf("C pc[%ld] %lx\n", i, pc);
199    if (prev_pc - pc < kMaxOffset || pc - prev_pc < kMaxOffset) {
200      uintptr_t offset = (int64_t)(pc - prev_pc);
201      offset |= (1U << 31);
202      if (c_index >= size) break;
203      // Printf("C co[%ld] offset %lx\n", i, offset);
204      compressed[c_index++] = offset;
205    } else {
206      uintptr_t hi = pc >> 32;
207      uintptr_t lo = (pc << 32) >> 32;
208      CHECK((hi & (1 << 31)) == 0);
209      if (c_index + 1 >= size) break;
210      // Printf("C co[%ld] hi/lo: %lx %lx\n", c_index, hi, lo);
211      compressed[c_index++] = hi;
212      compressed[c_index++] = lo;
213    }
214    res++;
215    prev_pc = pc;
216  }
217  for (size_t i = c_index; i < size; i++) {
218    compressed[i] = 0;
219  }
220#endif  // __WORDSIZE
221
222  // debug-only code
223#if 0
224  AsanStackTrace check_stack;
225  UncompressStack(&check_stack, compressed, size);
226  if (res < check_stack.size) {
227    Printf("res %ld check_stack.size %ld; c_size %ld\n", res,
228           check_stack.size, size);
229  }
230  // |res| may be greater than check_stack.size, because
231  // UncompressStack(CompressStack(stack)) eliminates the 0x0 frames.
232  CHECK(res >= check_stack.size);
233  CHECK(0 == memcmp(check_stack.trace, stack->trace,
234                    check_stack.size * sizeof(uintptr_t)));
235#endif
236
237  return res;
238}
239
240void AsanStackTrace::UncompressStack(AsanStackTrace *stack,
241                                     uint32_t *compressed, size_t size) {
242#if __WORDSIZE == 32
243  // Don't uncompress, just copy.
244  stack->size = 0;
245  for (size_t i = 0; i < size && i < kStackTraceMax; i++) {
246    if (!compressed[i]) break;
247    stack->size++;
248    stack->trace[i] = compressed[i];
249  }
250#else  // 64 bits, uncompress
251  uintptr_t prev_pc = 0;
252  stack->size = 0;
253  for (size_t i = 0; i < size && stack->size < kStackTraceMax; i++) {
254    uint32_t x = compressed[i];
255    uintptr_t pc = 0;
256    if (x & (1U << 31)) {
257      // Printf("U co[%ld] offset: %x\n", i, x);
258      // this is an offset
259      int32_t offset = x;
260      offset = (offset << 1) >> 1;  // remove the 31-byte and sign-extend.
261      pc = prev_pc + offset;
262      CHECK(pc);
263    } else {
264      // CHECK(i + 1 < size);
265      if (i + 1 >= size) break;
266      uintptr_t hi = x;
267      uintptr_t lo = compressed[i+1];
268      // Printf("U co[%ld] hi/lo: %lx %lx\n", i, hi, lo);
269      i++;
270      pc = (hi << 32) | lo;
271      if (!pc) break;
272    }
273    // Printf("U pc[%ld] %lx\n", stack->size, pc);
274    stack->trace[stack->size++] = pc;
275    prev_pc = pc;
276  }
277#endif  // __WORDSIZE
278}
279
280}  // namespace __asan
281