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
31 typedef uint64_t word_t;
32 #else
33 #define PRIPTR "08" PRIxPTR
34 typedef uint32_t word_t;
35 #endif
36 
37 enum 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 
55 struct 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__)
66 struct __darwin_ucontext;
67 typedef __darwin_ucontext ucontext_t;
68 #else
69 struct ucontext;
70 typedef ucontext ucontext_t;
71 #endif
72 
73 struct backtrace_stackinfo_t {
74   uint64_t start;
75   uint64_t end;
76   const uint8_t* data;
77 };
78 
79 class Backtrace {
80 public:
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   virtual std::string GetFunctionName(uintptr_t pc, uintptr_t* offset);
109 
110   // Fill in the map data associated with the given pc.
111   virtual void FillInMap(uintptr_t pc, backtrace_map_t* map);
112 
113   // Read the data at a specific address.
114   virtual bool ReadWord(uintptr_t ptr, word_t* out_value) = 0;
115 
116   // Read arbitrary data from a specific address. If a read request would
117   // span from one map to another, this call only reads up until the end
118   // of the current map.
119   // Returns the total number of bytes actually read.
120   virtual size_t Read(uintptr_t addr, uint8_t* buffer, size_t bytes) = 0;
121 
122   // Create a string representing the formatted line of backtrace information
123   // for a single frame.
124   virtual std::string FormatFrameData(size_t frame_num);
125   virtual std::string FormatFrameData(const backtrace_frame_data_t* frame);
126 
Pid()127   pid_t Pid() const { return pid_; }
Tid()128   pid_t Tid() const { return tid_; }
NumFrames()129   size_t NumFrames() const { return frames_.size(); }
130 
GetFrame(size_t frame_num)131   const backtrace_frame_data_t* GetFrame(size_t frame_num) {
132     if (frame_num >= frames_.size()) {
133       return NULL;
134     }
135     return &frames_[frame_num];
136   }
137 
138   typedef std::vector<backtrace_frame_data_t>::iterator iterator;
begin()139   iterator begin() { return frames_.begin(); }
end()140   iterator end() { return frames_.end(); }
141 
142   typedef std::vector<backtrace_frame_data_t>::const_iterator const_iterator;
begin()143   const_iterator begin() const { return frames_.begin(); }
end()144   const_iterator end() const { return frames_.end(); }
145 
GetMap()146   BacktraceMap* GetMap() { return map_; }
147 
GetError()148   BacktraceUnwindError GetError() { return error_; }
149 
150   std::string GetErrorString(BacktraceUnwindError error);
151 
152 protected:
153   Backtrace(pid_t pid, pid_t tid, BacktraceMap* map);
154 
155   // The name returned is not demangled, GetFunctionName() takes care of
156   // demangling the name.
157   virtual std::string GetFunctionNameRaw(uintptr_t pc, uintptr_t* offset) = 0;
158 
159   virtual bool VerifyReadWordArgs(uintptr_t ptr, word_t* out_value);
160 
161   bool BuildMap();
162 
163   pid_t pid_;
164   pid_t tid_;
165 
166   BacktraceMap* map_;
167   bool map_shared_;
168 
169   std::vector<backtrace_frame_data_t> frames_;
170 
171   BacktraceUnwindError error_;
172 };
173 
174 #endif // _BACKTRACE_BACKTRACE_H
175