aboutsummaryrefslogtreecommitdiff
path: root/gold/dwarf_reader.h
blob: 4d28518bcb66ee700eefd1c01d925d98e2b57672 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
// dwarf_reader.h -- parse dwarf2/3 debug information for gold  -*- C++ -*-

// Copyright 2007 Free Software Foundation, Inc.
// Written by Ian Lance Taylor <iant@google.com>.

// This file is part of gold.

// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
// MA 02110-1301, USA.

#ifndef GOLD_DWARF_READER_H
#define GOLD_DWARF_READER_H

#include <vector>
#include <map>

#include "elfcpp.h"
#include "elfcpp_swap.h"
#include "dwarf.h"
#include "reloc.h"

namespace gold
{

template<int size, bool big_endian>
class Track_relocs;
struct LineStateMachine;

// We can't do better than to keep the offsets in a sorted vector.
// Here, offset is the key, and file_num/line_num is the value.
struct Offset_to_lineno_entry
{
  off_t offset;
  int header_num;  // which file-list to use (i.e. which .o file are we in)
  int file_num;    // a pointer into files_
  int line_num;    // the line number in the source file
  // Offsets are unique within a section, so that's a sufficient sort key.
  bool operator<(const Offset_to_lineno_entry& that) const
  { return this->offset < that.offset; }
};

// This class is used to read the line information from the debugging
// section of an object file.

class Dwarf_line_info
{
 public:
  Dwarf_line_info()
  { }

  virtual
  ~Dwarf_line_info()
  { }

  // Given a section number and an offset, returns the associated
  // file and line-number, as a string: "file:lineno".  If unable
  // to do the mapping, returns the empty string.  You must call
  // read_line_mappings() before calling this function.
  std::string
  addr2line(unsigned int shndx, off_t offset)
  { return do_addr2line(shndx, offset); }

  // A helper function for a single addr2line lookup.  It uses
  // parameters() to figure out the size and endianness.  This is less
  // efficient than using the templatized size and endianness, so only
  // call this from an un-templatized context.
  static std::string
  one_addr2line(Object* object, unsigned int shndx, off_t offset);

 private:
  virtual std::string
  do_addr2line(unsigned int shndx, off_t offset) = 0;
};

template<int size, bool big_endian>
class Sized_dwarf_line_info : public Dwarf_line_info
{
 public:
  // Initializes a .debug_line reader for a given object file.
  // If SHNDX is specified and non-negative, only read the debug
  // information that pertains to the specified section.
  Sized_dwarf_line_info(Object* object, off_t read_shndx = -1U);

 private:
  std::string
  do_addr2line(unsigned int shndx, off_t offset);

  // Start processing line info, and populates the offset_map_.
  // If SHNDX is non-negative, only store debug information that
  // pertains to the specified section.
  void
  read_line_mappings(off_t shndx);

  // Reads the relocation section associated with .debug_line and
  // stores relocation information in reloc_map_.
  void
  read_relocs();

  // Looks in the symtab to see what section a symbol is in.
  unsigned int
  symbol_section(unsigned int sym,
                 typename elfcpp::Elf_types<size>::Elf_Addr* value);

  // Reads the DWARF2/3 header for this line info.  Each takes as input
  // a starting buffer position, and returns the ending position.
  const unsigned char*
  read_header_prolog(const unsigned char* lineptr);

  const unsigned char*
  read_header_tables(const unsigned char* lineptr);

  // Reads the DWARF2/3 line information.  If shndx is non-negative,
  // discard all line information that doesn't pertain to the given
  // section.
  const unsigned char*
  read_lines(const unsigned char* lineptr, off_t shndx);

  // Process a single line info opcode at START using the state
  // machine at LSM.  Return true if we should define a line using the
  // current state of the line state machine.  Place the length of the
  // opcode in LEN.
  bool
  process_one_opcode(const unsigned char* start,
                     struct LineStateMachine* lsm, size_t* len);

  // Some parts of processing differ depending on whether the input
  // was a .o file or not.
  bool input_is_relobj();

  // If we saw anything amiss while parsing, we set this to false.
  // Then addr2line will always fail (rather than return possibly-
  // corrupt data).
  bool data_valid_;

  // A DWARF2/3 line info header.  This is not the same size as in the
  // actual file, as the one in the file may have a 32 bit or 64 bit
  // lengths.

  struct Dwarf_line_infoHeader
  {
    off_t total_length;
    int version;
    off_t prologue_length;
    int min_insn_length; // insn stands for instructin
    bool default_is_stmt; // stmt stands for statement
    signed char line_base;
    int line_range;
    unsigned char opcode_base;
    std::vector<unsigned char> std_opcode_lengths;
    int offset_size;
  } header_;

  // buffer is the buffer for our line info, starting at exactly where
  // the line info to read is.
  const unsigned char* buffer_;
  const unsigned char* buffer_end_;

  // This has relocations that point into buffer.
  Track_relocs<size, big_endian> track_relocs_;

  // This is used to figure out what section to apply a relocation to.
  const unsigned char* symtab_buffer_;
  section_size_type symtab_buffer_size_;

  // Holds the directories and files as we see them.  We have an array
  // of directory-lists, one for each .o file we're reading (usually
  // there will just be one, but there may be more if input is a .so).
  std::vector<std::vector<std::string> > directories_;
  // The first part is an index into directories_, the second the filename.
  std::vector<std::vector< std::pair<int, std::string> > > files_;

  // An index into the current directories_ and files_ vectors.
  int current_header_index_;

  // A sorted map from offset of the relocation target to the shndx
  // and addend for the relocation.
  typedef std::map<typename elfcpp::Elf_types<size>::Elf_Addr,
                   std::pair<unsigned int,
                             typename elfcpp::Elf_types<size>::Elf_Swxword> >
  Reloc_map;
  Reloc_map reloc_map_;

  // We have a vector of offset->lineno entries for every input section.
  typedef Unordered_map<unsigned int, std::vector<Offset_to_lineno_entry> >
  Lineno_map;

  Lineno_map line_number_map_;
};

} // End namespace gold.

#endif // !defined(GOLD_DWARF_READER_H)