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 <string> 42 43#include "common/module.h" 44#include "common/dwarf/dwarf2reader.h" 45#include "common/using_std_string.h" 46 47namespace google_breakpad { 48 49// A class for producing a vector of google_breakpad::Module::Line 50// instances from parsed DWARF line number data. 51// 52// An instance of this class can be provided as a handler to a 53// dwarf2reader::LineInfo DWARF line number information parser. The 54// handler accepts source location information from the parser and 55// uses it to produce a vector of google_breakpad::Module::Line 56// objects, referring to google_breakpad::Module::File objects added 57// to a particular google_breakpad::Module. 58// 59// GNU toolchain omitted sections support: 60// ====================================== 61// 62// Given the right options, the GNU toolchain will omit unreferenced 63// functions from the final executable. Unfortunately, when it does so, it 64// does not remove the associated portions of the DWARF line number 65// program; instead, it gives the DW_LNE_set_address instructions referring 66// to the now-deleted code addresses of zero. Given this input, the DWARF 67// line parser will call AddLine with a series of lines starting at address 68// zero. For example, here is the output from 'readelf -wl' for a program 69// with four functions, the first three of which have been omitted: 70// 71// Line Number Statements: 72// Extended opcode 2: set Address to 0x0 73// Advance Line by 14 to 15 74// Copy 75// Special opcode 48: advance Address by 3 to 0x3 and Line by 1 to 16 76// Special opcode 119: advance Address by 8 to 0xb and Line by 2 to 18 77// Advance PC by 2 to 0xd 78// Extended opcode 1: End of Sequence 79// 80// Extended opcode 2: set Address to 0x0 81// Advance Line by 14 to 15 82// Copy 83// Special opcode 48: advance Address by 3 to 0x3 and Line by 1 to 16 84// Special opcode 119: advance Address by 8 to 0xb and Line by 2 to 18 85// Advance PC by 2 to 0xd 86// Extended opcode 1: End of Sequence 87// 88// Extended opcode 2: set Address to 0x0 89// Advance Line by 19 to 20 90// Copy 91// Special opcode 48: advance Address by 3 to 0x3 and Line by 1 to 21 92// Special opcode 76: advance Address by 5 to 0x8 and Line by 1 to 22 93// Advance PC by 2 to 0xa 94// Extended opcode 1: End of Sequence 95// 96// Extended opcode 2: set Address to 0x80483a4 97// Advance Line by 23 to 24 98// Copy 99// Special opcode 202: advance Address by 14 to 0x80483b2 and Line by 1 to 25 100// Special opcode 76: advance Address by 5 to 0x80483b7 and Line by 1 to 26 101// Advance PC by 6 to 0x80483bd 102// Extended opcode 1: End of Sequence 103// 104// Instead of collecting runs of lines describing code that is not there, 105// we try to recognize and drop them. Since the linker doesn't explicitly 106// distinguish references to dropped sections from genuine references to 107// code at address zero, we must use a heuristic. We have chosen: 108// 109// - If a line starts at address zero, omit it. (On the platforms 110// breakpad targets, it is extremely unlikely that there will be code 111// at address zero.) 112// 113// - If a line starts immediately after an omitted line, omit it too. 114class DwarfLineToModule: public dwarf2reader::LineInfoHandler { 115 public: 116 // As the DWARF line info parser passes us line records, add source 117 // files to MODULE, and add all lines to the end of LINES. LINES 118 // need not be empty. If the parser hands us a zero-length line, we 119 // omit it. If the parser hands us a line that extends beyond the 120 // end of the address space, we clip it. It's up to our client to 121 // sort out which lines belong to which functions; we don't add them 122 // to any particular function in MODULE ourselves. 123 DwarfLineToModule(Module *module, const string& compilation_dir, 124 vector<Module::Line> *lines) 125 : module_(module), 126 compilation_dir_(compilation_dir), 127 lines_(lines), 128 highest_file_number_(-1), 129 omitted_line_end_(0), 130 warned_bad_file_number_(false), 131 warned_bad_directory_number_(false) { } 132 133 ~DwarfLineToModule() { } 134 135 void DefineDir(const string &name, uint32 dir_num); 136 void DefineFile(const string &name, int32 file_num, 137 uint32 dir_num, uint64 mod_time, 138 uint64 length); 139 void AddLine(uint64 address, uint64 length, 140 uint32 file_num, uint32 line_num, uint32 column_num); 141 142 private: 143 144 typedef std::map<uint32, string> DirectoryTable; 145 typedef std::map<uint32, Module::File *> FileTable; 146 147 // The module we're contributing debugging info to. Owned by our 148 // client. 149 Module *module_; 150 151 // The compilation directory for the current compilation unit whose 152 // lines are being accumulated. 153 string compilation_dir_; 154 155 // The vector of lines we're accumulating. Owned by our client. 156 // 157 // In a Module, as in a breakpad symbol file, lines belong to 158 // specific functions, but DWARF simply assigns lines to addresses; 159 // one must infer the line/function relationship using the 160 // functions' beginning and ending addresses. So we can't add these 161 // to the appropriate function from module_ until we've read the 162 // function info as well. Instead, we accumulate lines here, and let 163 // whoever constructed this sort it all out. 164 vector<Module::Line> *lines_; 165 166 // A table mapping directory numbers to paths. 167 DirectoryTable directories_; 168 169 // A table mapping file numbers to Module::File pointers. 170 FileTable files_; 171 172 // The highest file number we've seen so far, or -1 if we've seen 173 // none. Used for dynamically defined file numbers. 174 int32 highest_file_number_; 175 176 // This is the ending address of the last line we omitted, or zero if we 177 // didn't omit the previous line. It is zero before we have received any 178 // AddLine calls. 179 uint64 omitted_line_end_; 180 181 // True if we've warned about: 182 bool warned_bad_file_number_; // bad file numbers 183 bool warned_bad_directory_number_; // bad directory numbers 184}; 185 186} // namespace google_breakpad 187 188#endif // COMMON_LINUX_DWARF_LINE_TO_MODULE_H 189