1 : // -*- mode: c++ -*-
2 :
3 : // Copyright (c) 2010 Google Inc.
4 : // All rights reserved.
5 : //
6 : // Redistribution and use in source and binary forms, with or without
7 : // modification, are permitted provided that the following conditions are
8 : // met:
9 : //
10 : // * Redistributions of source code must retain the above copyright
11 : // notice, this list of conditions and the following disclaimer.
12 : // * Redistributions in binary form must reproduce the above
13 : // copyright notice, this list of conditions and the following disclaimer
14 : // in the documentation and/or other materials provided with the
15 : // distribution.
16 : // * Neither the name of Google Inc. nor the names of its
17 : // contributors may be used to endorse or promote products derived from
18 : // this software without specific prior written permission.
19 : //
20 : // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
21 : // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22 : // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
23 : // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
24 : // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
25 : // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
26 : // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27 : // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28 : // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29 : // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
30 : // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 :
32 : // Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
33 :
34 : // The DwarfLineToModule class accepts line number information from a
35 : // DWARF parser and adds it to a google_breakpad::Module. The Module
36 : // can write that data out as a Breakpad symbol file.
37 :
38 : #ifndef COMMON_LINUX_DWARF_LINE_TO_MODULE_H
39 : #define COMMON_LINUX_DWARF_LINE_TO_MODULE_H
40 :
41 : #include "common/module.h"
42 : #include "common/dwarf/dwarf2reader.h"
43 :
44 : namespace google_breakpad {
45 :
46 : // A class for producing a vector of google_breakpad::Module::Line
47 : // instances from parsed DWARF line number data.
48 : //
49 : // An instance of this class can be provided as a handler to a
50 : // dwarf2reader::LineInfo DWARF line number information parser. The
51 : // handler accepts source location information from the parser and
52 : // uses it to produce a vector of google_breakpad::Module::Line
53 : // objects, referring to google_breakpad::Module::File objects added
54 : // to a particular google_breakpad::Module.
55 : //
56 : // GNU toolchain omitted sections support:
57 : // ======================================
58 : //
59 : // Given the right options, the GNU toolchain will omit unreferenced
60 : // functions from the final executable. Unfortunately, when it does so, it
61 : // does not remove the associated portions of the DWARF line number
62 : // program; instead, it gives the DW_LNE_set_address instructions referring
63 : // to the now-deleted code addresses of zero. Given this input, the DWARF
64 : // line parser will call AddLine with a series of lines starting at address
65 : // zero. For example, here is the output from 'readelf -wl' for a program
66 : // with four functions, the first three of which have been omitted:
67 : //
68 : // Line Number Statements:
69 : // Extended opcode 2: set Address to 0x0
70 : // Advance Line by 14 to 15
71 : // Copy
72 : // Special opcode 48: advance Address by 3 to 0x3 and Line by 1 to 16
73 : // Special opcode 119: advance Address by 8 to 0xb and Line by 2 to 18
74 : // Advance PC by 2 to 0xd
75 : // Extended opcode 1: End of Sequence
76 : //
77 : // Extended opcode 2: set Address to 0x0
78 : // Advance Line by 14 to 15
79 : // Copy
80 : // Special opcode 48: advance Address by 3 to 0x3 and Line by 1 to 16
81 : // Special opcode 119: advance Address by 8 to 0xb and Line by 2 to 18
82 : // Advance PC by 2 to 0xd
83 : // Extended opcode 1: End of Sequence
84 : //
85 : // Extended opcode 2: set Address to 0x0
86 : // Advance Line by 19 to 20
87 : // Copy
88 : // Special opcode 48: advance Address by 3 to 0x3 and Line by 1 to 21
89 : // Special opcode 76: advance Address by 5 to 0x8 and Line by 1 to 22
90 : // Advance PC by 2 to 0xa
91 : // Extended opcode 1: End of Sequence
92 : //
93 : // Extended opcode 2: set Address to 0x80483a4
94 : // Advance Line by 23 to 24
95 : // Copy
96 : // Special opcode 202: advance Address by 14 to 0x80483b2 and Line by 1 to 25
97 : // Special opcode 76: advance Address by 5 to 0x80483b7 and Line by 1 to 26
98 : // Advance PC by 6 to 0x80483bd
99 : // Extended opcode 1: End of Sequence
100 : //
101 : // Instead of collecting runs of lines describing code that is not there,
102 : // we try to recognize and drop them. Since the linker doesn't explicitly
103 : // distinguish references to dropped sections from genuine references to
104 : // code at address zero, we must use a heuristic. We have chosen:
105 : //
106 : // - If a line starts at address zero, omit it. (On the platforms
107 : // breakpad targets, it is extremely unlikely that there will be code
108 : // at address zero.)
109 : //
110 : // - If a line starts immediately after an omitted line, omit it too.
111 : class DwarfLineToModule: public dwarf2reader::LineInfoHandler {
112 : public:
113 : // As the DWARF line info parser passes us line records, add source
114 : // files to MODULE, and add all lines to the end of LINES. LINES
115 : // need not be empty. If the parser hands us a zero-length line, we
116 : // omit it. If the parser hands us a line that extends beyond the
117 : // end of the address space, we clip it. It's up to our client to
118 : // sort out which lines belong to which functions; we don't add them
119 : // to any particular function in MODULE ourselves.
120 4723 : DwarfLineToModule(Module *module, vector<Module::Line> *lines)
121 : : module_(module),
122 : lines_(lines),
123 : highest_file_number_(-1),
124 : omitted_line_end_(0),
125 : warned_bad_file_number_(false),
126 4723 : warned_bad_directory_number_(false) { }
127 :
128 4723 : ~DwarfLineToModule() { }
129 :
130 : void DefineDir(const std::string &name, uint32 dir_num);
131 : void DefineFile(const std::string &name, int32 file_num,
132 : uint32 dir_num, uint64 mod_time,
133 : uint64 length);
134 : void AddLine(uint64 address, uint64 length,
135 : uint32 file_num, uint32 line_num, uint32 column_num);
136 :
137 : private:
138 :
139 : typedef std::map<uint32, std::string> DirectoryTable;
140 : typedef std::map<uint32, Module::File *> FileTable;
141 :
142 : // The module we're contributing debugging info to. Owned by our
143 : // client.
144 : Module *module_;
145 :
146 : // The vector of lines we're accumulating. Owned by our client.
147 : //
148 : // In a Module, as in a breakpad symbol file, lines belong to
149 : // specific functions, but DWARF simply assigns lines to addresses;
150 : // one must infer the line/function relationship using the
151 : // functions' beginning and ending addresses. So we can't add these
152 : // to the appropriate function from module_ until we've read the
153 : // function info as well. Instead, we accumulate lines here, and let
154 : // whoever constructed this sort it all out.
155 : vector<Module::Line> *lines_;
156 :
157 : // A table mapping directory numbers to paths.
158 : DirectoryTable directories_;
159 :
160 : // A table mapping file numbers to Module::File pointers.
161 : FileTable files_;
162 :
163 : // The highest file number we've seen so far, or -1 if we've seen
164 : // none. Used for dynamically defined file numbers.
165 : int32 highest_file_number_;
166 :
167 : // This is the ending address of the last line we omitted, or zero if we
168 : // didn't omit the previous line. It is zero before we have received any
169 : // AddLine calls.
170 : uint64 omitted_line_end_;
171 :
172 : // True if we've warned about:
173 : bool warned_bad_file_number_; // bad file numbers
174 : bool warned_bad_directory_number_; // bad directory numbers
175 : };
176 :
177 : } // namespace google_breakpad
178 :
179 : #endif // COMMON_LINUX_DWARF_LINE_TO_MODULE_H
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