// dwarf_reader.h -- parse dwarf2/3 debug information for gold -*- C++ -*- // Copyright 2007, 2008 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; uint64_t read_unsigned_LEB_128(const unsigned char* buffer, size_t* len); int64_t read_signed_LEB_128(const unsigned char* buffer, size_t* len); // 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 also keeps a // cache of the last CACHE_SIZE Dwarf_line_info objects it created; // set to 0 not to cache at all. The larger CACHE_SIZE is, the more // chance this routine won't have to re-create a Dwarf_line_info // object for its addr2line computation; such creations are slow. // NOTE: Not thread-safe, so only call from one thread at a time. static std::string one_addr2line(Object* object, unsigned int shndx, off_t offset, size_t cache_size); // This reclaims all the memory that one_addr2line may have cached. // Use this when you know you will not be calling one_addr2line again. static void clear_addr2line_cache(); 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(Object*, off_t shndx); // Reads the relocation section associated with .debug_line and // stores relocation information in reloc_map_. void read_relocs(Object*); // Looks in the symtab to see what section a symbol is in. unsigned int symbol_section(Object*, unsigned int sym, typename elfcpp::Elf_types<size>::Elf_Addr* value, bool* is_ordinary); // 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)