1// dwarf_reader.h -- parse dwarf2/3 debug information for gold -*- C++ -*- 2 3// Copyright 2007, 2008, 2009 Free Software Foundation, Inc. 4// Written by Ian Lance Taylor <iant@google.com>. 5 6// This file is part of gold. 7 8// This program is free software; you can redistribute it and/or modify 9// it under the terms of the GNU General Public License as published by 10// the Free Software Foundation; either version 3 of the License, or 11// (at your option) any later version. 12 13// This program is distributed in the hope that it will be useful, 14// but WITHOUT ANY WARRANTY; without even the implied warranty of 15// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16// GNU General Public License for more details. 17 18// You should have received a copy of the GNU General Public License 19// along with this program; if not, write to the Free Software 20// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, 21// MA 02110-1301, USA. 22 23#ifndef GOLD_DWARF_READER_H 24#define GOLD_DWARF_READER_H 25 26#include <vector> 27#include <map> 28 29#include "elfcpp.h" 30#include "elfcpp_swap.h" 31#include "dwarf.h" 32#include "reloc.h" 33 34namespace gold 35{ 36 37template<int size, bool big_endian> 38class Track_relocs; 39struct LineStateMachine; 40 41// We can't do better than to keep the offsets in a sorted vector. 42// Here, offset is the key, and file_num/line_num is the value. 43struct Offset_to_lineno_entry 44{ 45 off_t offset; 46 int header_num; // which file-list to use (i.e. which .o file are we in) 47 int file_num; // a pointer into files_ 48 int line_num; // the line number in the source file 49 // Offsets are unique within a section, so that's a sufficient sort key. 50 bool operator<(const Offset_to_lineno_entry& that) const 51 { return this->offset < that.offset; } 52}; 53 54// This class is used to read the line information from the debugging 55// section of an object file. 56 57class Dwarf_line_info 58{ 59 public: 60 Dwarf_line_info() 61 { } 62 63 virtual 64 ~Dwarf_line_info() 65 { } 66 67 // Given a section number and an offset, returns the associated 68 // file and line-number, as a string: "file:lineno". If unable 69 // to do the mapping, returns the empty string. You must call 70 // read_line_mappings() before calling this function. 71 std::string 72 addr2line(unsigned int shndx, off_t offset) 73 { return do_addr2line(shndx, offset); } 74 75 // A helper function for a single addr2line lookup. It also keeps a 76 // cache of the last CACHE_SIZE Dwarf_line_info objects it created; 77 // set to 0 not to cache at all. The larger CACHE_SIZE is, the more 78 // chance this routine won't have to re-create a Dwarf_line_info 79 // object for its addr2line computation; such creations are slow. 80 // NOTE: Not thread-safe, so only call from one thread at a time. 81 static std::string 82 one_addr2line(Object* object, unsigned int shndx, off_t offset, 83 size_t cache_size); 84 85 // This reclaims all the memory that one_addr2line may have cached. 86 // Use this when you know you will not be calling one_addr2line again. 87 static void 88 clear_addr2line_cache(); 89 90 private: 91 virtual std::string 92 do_addr2line(unsigned int shndx, off_t offset) = 0; 93}; 94 95template<int size, bool big_endian> 96class Sized_dwarf_line_info : public Dwarf_line_info 97{ 98 public: 99 // Initializes a .debug_line reader for a given object file. 100 // If SHNDX is specified and non-negative, only read the debug 101 // information that pertains to the specified section. 102 Sized_dwarf_line_info(Object* object, unsigned int read_shndx = -1U); 103 104 private: 105 std::string 106 do_addr2line(unsigned int shndx, off_t offset); 107 108 // Start processing line info, and populates the offset_map_. 109 // If SHNDX is non-negative, only store debug information that 110 // pertains to the specified section. 111 void 112 read_line_mappings(Object*, unsigned int shndx); 113 114 // Reads the relocation section associated with .debug_line and 115 // stores relocation information in reloc_map_. 116 void 117 read_relocs(Object*); 118 119 // Looks in the symtab to see what section a symbol is in. 120 unsigned int 121 symbol_section(Object*, unsigned int sym, 122 typename elfcpp::Elf_types<size>::Elf_Addr* value, 123 bool* is_ordinary); 124 125 // Reads the DWARF2/3 header for this line info. Each takes as input 126 // a starting buffer position, and returns the ending position. 127 const unsigned char* 128 read_header_prolog(const unsigned char* lineptr); 129 130 const unsigned char* 131 read_header_tables(const unsigned char* lineptr); 132 133 // Reads the DWARF2/3 line information. If shndx is non-negative, 134 // discard all line information that doesn't pertain to the given 135 // section. 136 const unsigned char* 137 read_lines(const unsigned char* lineptr, unsigned int shndx); 138 139 // Process a single line info opcode at START using the state 140 // machine at LSM. Return true if we should define a line using the 141 // current state of the line state machine. Place the length of the 142 // opcode in LEN. 143 bool 144 process_one_opcode(const unsigned char* start, 145 struct LineStateMachine* lsm, size_t* len); 146 147 // Some parts of processing differ depending on whether the input 148 // was a .o file or not. 149 bool input_is_relobj(); 150 151 // If we saw anything amiss while parsing, we set this to false. 152 // Then addr2line will always fail (rather than return possibly- 153 // corrupt data). 154 bool data_valid_; 155 156 // A DWARF2/3 line info header. This is not the same size as in the 157 // actual file, as the one in the file may have a 32 bit or 64 bit 158 // lengths. 159 160 struct Dwarf_line_infoHeader 161 { 162 off_t total_length; 163 int version; 164 off_t prologue_length; 165 int min_insn_length; // insn stands for instructin 166 bool default_is_stmt; // stmt stands for statement 167 signed char line_base; 168 int line_range; 169 unsigned char opcode_base; 170 std::vector<unsigned char> std_opcode_lengths; 171 int offset_size; 172 } header_; 173 174 // buffer is the buffer for our line info, starting at exactly where 175 // the line info to read is. 176 const unsigned char* buffer_; 177 const unsigned char* buffer_end_; 178 179 // This has relocations that point into buffer. 180 Track_relocs<size, big_endian> track_relocs_; 181 182 // This is used to figure out what section to apply a relocation to. 183 const unsigned char* symtab_buffer_; 184 section_size_type symtab_buffer_size_; 185 186 // Holds the directories and files as we see them. We have an array 187 // of directory-lists, one for each .o file we're reading (usually 188 // there will just be one, but there may be more if input is a .so). 189 std::vector<std::vector<std::string> > directories_; 190 // The first part is an index into directories_, the second the filename. 191 std::vector<std::vector< std::pair<int, std::string> > > files_; 192 193 // An index into the current directories_ and files_ vectors. 194 int current_header_index_; 195 196 // A sorted map from offset of the relocation target to the shndx 197 // and addend for the relocation. 198 typedef std::map<typename elfcpp::Elf_types<size>::Elf_Addr, 199 std::pair<unsigned int, 200 typename elfcpp::Elf_types<size>::Elf_Swxword> > 201 Reloc_map; 202 Reloc_map reloc_map_; 203 204 // We have a vector of offset->lineno entries for every input section. 205 typedef Unordered_map<unsigned int, std::vector<Offset_to_lineno_entry> > 206 Lineno_map; 207 208 Lineno_map line_number_map_; 209}; 210 211} // End namespace gold. 212 213#endif // !defined(GOLD_DWARF_READER_H) 214