1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "base/debug/stack_trace.h"
6
7#include <android/log.h>
8#include <unwind.h>
9
10#include "base/debug/proc_maps_linux.h"
11#include "base/strings/stringprintf.h"
12#include "base/threading/thread_restrictions.h"
13
14namespace {
15
16struct StackCrawlState {
17  StackCrawlState(uintptr_t* frames, size_t max_depth)
18      : frames(frames),
19        frame_count(0),
20        max_depth(max_depth),
21        have_skipped_self(false) {}
22
23  uintptr_t* frames;
24  size_t frame_count;
25  size_t max_depth;
26  bool have_skipped_self;
27};
28
29// Clang's unwind.h doesn't provide _Unwind_GetIP on ARM, refer to
30// http://llvm.org/bugs/show_bug.cgi?id=16564 for details.
31#if defined(__clang__)
32uintptr_t _Unwind_GetIP(_Unwind_Context* context) {
33  uintptr_t ip = 0;
34  _Unwind_VRS_Get(context, _UVRSC_CORE, 15, _UVRSD_UINT32, &ip);
35  return ip & ~static_cast<uintptr_t>(0x1);  // Remove thumb mode bit.
36}
37#endif
38
39_Unwind_Reason_Code TraceStackFrame(_Unwind_Context* context, void* arg) {
40  StackCrawlState* state = static_cast<StackCrawlState*>(arg);
41  uintptr_t ip = _Unwind_GetIP(context);
42
43  // The first stack frame is this function itself.  Skip it.
44  if (ip != 0 && !state->have_skipped_self) {
45    state->have_skipped_self = true;
46    return _URC_NO_REASON;
47  }
48
49  state->frames[state->frame_count++] = ip;
50  if (state->frame_count >= state->max_depth)
51    return _URC_END_OF_STACK;
52  return _URC_NO_REASON;
53}
54
55}  // namespace
56
57namespace base {
58namespace debug {
59
60bool EnableInProcessStackDumping() {
61  // When running in an application, our code typically expects SIGPIPE
62  // to be ignored.  Therefore, when testing that same code, it should run
63  // with SIGPIPE ignored as well.
64  // TODO(phajdan.jr): De-duplicate this SIGPIPE code.
65  struct sigaction action;
66  memset(&action, 0, sizeof(action));
67  action.sa_handler = SIG_IGN;
68  sigemptyset(&action.sa_mask);
69  return (sigaction(SIGPIPE, &action, NULL) == 0);
70}
71
72StackTrace::StackTrace() {
73  StackCrawlState state(reinterpret_cast<uintptr_t*>(trace_), kMaxTraces);
74  _Unwind_Backtrace(&TraceStackFrame, &state);
75  count_ = state.frame_count;
76}
77
78void StackTrace::PrintBacktrace() const {
79  std::string backtrace = ToString();
80  __android_log_write(ANDROID_LOG_ERROR, "chromium", backtrace.c_str());
81}
82
83// NOTE: Native libraries in APKs are stripped before installing. Print out the
84// relocatable address and library names so host computers can use tools to
85// symbolize and demangle (e.g., addr2line, c++filt).
86void StackTrace::OutputToStream(std::ostream* os) const {
87  std::string proc_maps;
88  std::vector<MappedMemoryRegion> regions;
89  // Allow IO to read /proc/self/maps. Reading this file doesn't hit the disk
90  // since it lives in procfs, and this is currently used to print a stack trace
91  // on fatal log messages in debug builds only. If the restriction is enabled
92  // then it will recursively trigger fatal failures when this enters on the
93  // UI thread.
94  base::ThreadRestrictions::ScopedAllowIO allow_io;
95  if (!ReadProcMaps(&proc_maps)) {
96    __android_log_write(
97        ANDROID_LOG_ERROR, "chromium", "Failed to read /proc/self/maps");
98  } else if (!ParseProcMaps(proc_maps, &regions)) {
99    __android_log_write(
100        ANDROID_LOG_ERROR, "chromium", "Failed to parse /proc/self/maps");
101  }
102
103  for (size_t i = 0; i < count_; ++i) {
104    // Subtract one as return address of function may be in the next
105    // function when a function is annotated as noreturn.
106    uintptr_t address = reinterpret_cast<uintptr_t>(trace_[i]) - 1;
107
108    std::vector<MappedMemoryRegion>::iterator iter = regions.begin();
109    while (iter != regions.end()) {
110      if (address >= iter->start && address < iter->end &&
111          !iter->path.empty()) {
112        break;
113      }
114      ++iter;
115    }
116
117    *os << base::StringPrintf("#%02d 0x%08x ", i, address);
118
119    if (iter != regions.end()) {
120      uintptr_t rel_pc = address - iter->start + iter->offset;
121      const char* path = iter->path.c_str();
122      *os << base::StringPrintf("%s+0x%08x", path, rel_pc);
123    } else {
124      *os << "<unknown>";
125    }
126
127    *os << "\n";
128  }
129}
130
131}  // namespace debug
132}  // namespace base
133