1/*
2 * Copyright (C) 2013 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef _BACKTRACE_BACKTRACE_H
18#define _BACKTRACE_BACKTRACE_H
19
20#include <inttypes.h>
21#include <stdint.h>
22
23#include <string>
24#include <vector>
25
26#include <backtrace/backtrace_constants.h>
27#include <backtrace/BacktraceMap.h>
28
29#if __LP64__
30#define PRIPTR "016" PRIxPTR
31typedef uint64_t word_t;
32#else
33#define PRIPTR "08" PRIxPTR
34typedef uint32_t word_t;
35#endif
36
37enum BacktraceUnwindError : uint32_t {
38  BACKTRACE_UNWIND_NO_ERROR,
39  // Something failed while trying to perform the setup to begin the unwind.
40  BACKTRACE_UNWIND_ERROR_SETUP_FAILED,
41  // There is no map information to use with the unwind.
42  BACKTRACE_UNWIND_ERROR_MAP_MISSING,
43  // An error occurred that indicates a programming error.
44  BACKTRACE_UNWIND_ERROR_INTERNAL,
45  // The thread to unwind has disappeared before the unwind can begin.
46  BACKTRACE_UNWIND_ERROR_THREAD_DOESNT_EXIST,
47  // The thread to unwind has not responded to a signal in a timely manner.
48  BACKTRACE_UNWIND_ERROR_THREAD_TIMEOUT,
49  // Attempt to do an unsupported operation.
50  BACKTRACE_UNWIND_ERROR_UNSUPPORTED_OPERATION,
51  // Attempt to do an offline unwind without a context.
52  BACKTRACE_UNWIND_ERROR_NO_CONTEXT,
53};
54
55struct backtrace_frame_data_t {
56  size_t num;             // The current fame number.
57  uintptr_t pc;           // The absolute pc.
58  uintptr_t sp;           // The top of the stack.
59  size_t stack_size;      // The size of the stack, zero indicate an unknown stack size.
60  backtrace_map_t map;    // The map associated with the given pc.
61  std::string func_name;  // The function name associated with this pc, NULL if not found.
62  uintptr_t func_offset;  // pc relative to the start of the function, only valid if func_name is not NULL.
63};
64
65#if defined(__APPLE__)
66struct __darwin_ucontext;
67typedef __darwin_ucontext ucontext_t;
68#else
69struct ucontext;
70typedef ucontext ucontext_t;
71#endif
72
73struct backtrace_stackinfo_t {
74  uint64_t start;
75  uint64_t end;
76  const uint8_t* data;
77};
78
79class Backtrace {
80public:
81  // Create the correct Backtrace object based on what is to be unwound.
82  // If pid < 0 or equals the current pid, then the Backtrace object
83  // corresponds to the current process.
84  // If pid < 0 or equals the current pid and tid >= 0, then the Backtrace
85  // object corresponds to a thread in the current process.
86  // If pid >= 0 and tid < 0, then the Backtrace object corresponds to a
87  // different process.
88  // Tracing a thread in a different process is not supported.
89  // If map is NULL, then create the map and manage it internally.
90  // If map is not NULL, the map is still owned by the caller.
91  static Backtrace* Create(pid_t pid, pid_t tid, BacktraceMap* map = NULL);
92
93  // Create an offline Backtrace object that can be used to do an unwind without a process
94  // that is still running. If cache_file is set to true, then elf information will be cached
95  // for this call. The cached information survives until the calling process ends. This means
96  // that subsequent calls to create offline Backtrace objects will continue to use the same
97  // cache. It also assumes that the elf files used for each offline unwind are the same.
98  static Backtrace* CreateOffline(pid_t pid, pid_t tid, BacktraceMap* map,
99                                  const backtrace_stackinfo_t& stack, bool cache_file = false);
100
101  virtual ~Backtrace();
102
103  // Get the current stack trace and store in the backtrace_ structure.
104  virtual bool Unwind(size_t num_ignore_frames, ucontext_t* context = NULL) = 0;
105
106  // Get the function name and offset into the function given the pc.
107  // If the string is empty, then no valid function name was found,
108  // or the pc is not in any valid map.
109  virtual std::string GetFunctionName(uintptr_t pc, uintptr_t* offset,
110                                      const backtrace_map_t* map = NULL);
111
112  // Fill in the map data associated with the given pc.
113  virtual void FillInMap(uintptr_t pc, backtrace_map_t* map);
114
115  // Read the data at a specific address.
116  virtual bool ReadWord(uintptr_t ptr, word_t* out_value) = 0;
117
118  // Read arbitrary data from a specific address. If a read request would
119  // span from one map to another, this call only reads up until the end
120  // of the current map.
121  // Returns the total number of bytes actually read.
122  virtual size_t Read(uintptr_t addr, uint8_t* buffer, size_t bytes) = 0;
123
124  // Create a string representing the formatted line of backtrace information
125  // for a single frame.
126  virtual std::string FormatFrameData(size_t frame_num);
127  virtual std::string FormatFrameData(const backtrace_frame_data_t* frame);
128
129  pid_t Pid() const { return pid_; }
130  pid_t Tid() const { return tid_; }
131  size_t NumFrames() const { return frames_.size(); }
132
133  const backtrace_frame_data_t* GetFrame(size_t frame_num) {
134    if (frame_num >= frames_.size()) {
135      return NULL;
136    }
137    return &frames_[frame_num];
138  }
139
140  typedef std::vector<backtrace_frame_data_t>::iterator iterator;
141  iterator begin() { return frames_.begin(); }
142  iterator end() { return frames_.end(); }
143
144  typedef std::vector<backtrace_frame_data_t>::const_iterator const_iterator;
145  const_iterator begin() const { return frames_.begin(); }
146  const_iterator end() const { return frames_.end(); }
147
148  BacktraceMap* GetMap() { return map_; }
149
150  BacktraceUnwindError GetError() { return error_; }
151
152  std::string GetErrorString(BacktraceUnwindError error);
153
154protected:
155  Backtrace(pid_t pid, pid_t tid, BacktraceMap* map);
156
157  // The name returned is not demangled, GetFunctionName() takes care of
158  // demangling the name.
159  virtual std::string GetFunctionNameRaw(uintptr_t pc, uintptr_t* offset) = 0;
160
161  virtual bool VerifyReadWordArgs(uintptr_t ptr, word_t* out_value);
162
163  bool BuildMap();
164
165  pid_t pid_;
166  pid_t tid_;
167
168  BacktraceMap* map_;
169  bool map_shared_;
170
171  std::vector<backtrace_frame_data_t> frames_;
172
173  BacktraceUnwindError error_;
174};
175
176#endif // _BACKTRACE_BACKTRACE_H
177