/* * Copyright (c) 1997, 2023, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code 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 * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ #ifndef SHARE_UTILITIES_ELFFILE_HPP #define SHARE_UTILITIES_ELFFILE_HPP #if !defined(_WINDOWS) && !defined(__APPLE__) && !defined(_AIX) #if defined(__OpenBSD__) #include #else #include #endif #include #ifdef _LP64 typedef Elf64_Half Elf_Half; typedef Elf64_Word Elf_Word; typedef Elf64_Off Elf_Off; typedef Elf64_Addr Elf_Addr; typedef Elf64_Ehdr Elf_Ehdr; typedef Elf64_Shdr Elf_Shdr; typedef Elf64_Phdr Elf_Phdr; typedef Elf64_Sym Elf_Sym; #if !defined(_ALLBSD_SOURCE) || defined(__APPLE__) #define ELF_ST_TYPE ELF64_ST_TYPE #endif #else typedef Elf32_Half Elf_Half; typedef Elf32_Word Elf_Word; typedef Elf32_Off Elf_Off; typedef Elf32_Addr Elf_Addr; typedef Elf32_Ehdr Elf_Ehdr; typedef Elf32_Shdr Elf_Shdr; typedef Elf32_Phdr Elf_Phdr; typedef Elf32_Sym Elf_Sym; #if !defined(_ALLBSD_SOURCE) || defined(__APPLE__) #define ELF_ST_TYPE ELF32_ST_TYPE #endif #endif #include "jvm_md.h" #include "globalDefinitions.hpp" #include "memory/allocation.hpp" #include "utilities/checkedCast.hpp" #include "utilities/decoder.hpp" #ifdef ASSERT // Helper macros to print different log levels during DWARF parsing #define DWARF_LOG_SUMMARY(format, ...) DWARF_LOG_WITH_LEVEL(1, format, ##__VA_ARGS__) // Same level as error logging #define DWARF_LOG_ERROR(format, ...) DWARF_LOG_WITH_LEVEL(1, format, ##__VA_ARGS__) #define DWARF_LOG_INFO(format, ...) DWARF_LOG_WITH_LEVEL(2, format, ##__VA_ARGS__) #define DWARF_LOG_DEBUG(format, ...) DWARF_LOG_WITH_LEVEL(3, format, ##__VA_ARGS__) #define DWARF_LOG_TRACE(format, ...) DWARF_LOG_WITH_LEVEL(4, format, ##__VA_ARGS__) #define DWARF_LOG_WITH_LEVEL(level, format, ...) \ if (TraceDwarfLevel >= level) { \ tty->print("[dwarf] "); \ tty->print_cr(format, ##__VA_ARGS__); \ } #else #define DWARF_LOG_SUMMARY(format, ...) #define DWARF_LOG_ERROR(format, ...) #define DWARF_LOG_INFO(format, ...) #define DWARF_LOG_DEBUG(format, ...) #define DWARF_LOG_TRACE(format, ...) #endif class ElfStringTable; class ElfSymbolTable; class ElfFuncDescTable; class DwarfFile; // ELF section, may or may not have cached data class ElfSection { private: Elf_Shdr _section_hdr; void* _section_data; NullDecoder::decoder_status _stat; public: ElfSection(FILE* fd, const Elf_Shdr& hdr); ~ElfSection(); NullDecoder::decoder_status status() const { return _stat; } const Elf_Shdr* section_header() const { return &_section_hdr; } const void* section_data() const { return (const void*)_section_data; } private: // load this section. // it return no_error, when it fails to cache the section data due to lack of memory NullDecoder::decoder_status load_section(FILE* const file, const Elf_Shdr& hdr); }; class FileReader : public StackObj { protected: FILE* const _fd; public: FileReader(FILE* const fd) : _fd(fd) {}; bool read(void* buf, size_t size); size_t read_buffer(void* buf, size_t size); virtual bool set_position(long offset); }; // Mark current position, so we can get back to it after // reads. class MarkedFileReader : public FileReader { protected: long _marked_pos; public: MarkedFileReader(FILE* const fd); ~MarkedFileReader(); bool has_mark() const { return _marked_pos >= 0; } }; // ElfFile is basically an elf file parser, which can lookup the symbol // that is the nearest to the given address. // Beware, this code is called from vm error reporting code, when vm is already // in "error" state, so there are scenarios, lookup will fail. We want this // part of code to be very defensive, and bait out if anything went wrong. class ElfFile: public CHeapObj { friend class ElfDecoder; private: // link ElfFiles ElfFile* _next; // Elf file char* _filepath; FILE* _file; // symbol tables ElfSymbolTable* _symbol_tables; // regular string tables ElfStringTable* _string_tables; // section header string table, used for finding section name ElfStringTable* _shdr_string_table; // function descriptors table ElfFuncDescTable* _funcDesc_table; NullDecoder::decoder_status _status; DwarfFile* _dwarf_file; static const char* USR_LIB_DEBUG_DIRECTORY; protected: // Elf header Elf_Ehdr _elfHdr; public: ElfFile(const char* filepath); virtual ~ElfFile(); bool decode(address addr, char* buf, int buflen, int* offset); bool same_elf_file(const char* filepath) const { assert(filepath != nullptr, "null file path"); return (_filepath != nullptr && !strcmp(filepath, _filepath)); } NullDecoder::decoder_status get_status() const { return _status; } // Returns true if the elf file is marked NOT to require an executable stack, // or if the file could not be opened. // Returns false if the elf file requires an executable stack, the stack flag // is not set at all, or if the file can not be read. // On systems other than linux it always returns false. static bool specifies_noexecstack(const char* filepath) NOT_LINUX({ return false; }); bool get_source_info(uint32_t offset_in_library, char* filename, size_t filename_len, int* line, bool is_pc_after_call); private: // sanity check, if the file is a real elf file static bool is_elf_file(Elf_Ehdr&); // parse this elf file NullDecoder::decoder_status parse_elf(const char* filename); // load string, symbol and function descriptor tables from the elf file NullDecoder::decoder_status load_tables(); ElfFile* next() const { return _next; } void set_next(ElfFile* file) { _next = file; } #if defined(PPC64) && !defined(ABI_ELFv2) // find a section by name, return section index // if there is no such section, return -1 int section_by_name(const char* name, Elf_Shdr& hdr); #endif // string tables are stored in a linked list void add_string_table(ElfStringTable* table); // symbol tables are stored in a linked list void add_symbol_table(ElfSymbolTable* table); // return a string table at specified section index ElfStringTable* get_string_table(int index); // Cleanup string, symbol and function descriptor tables void cleanup_tables(); bool create_new_dwarf_file(const char* filepath); // Struct to store the debug info read from the .gnu_debuglink section. struct DebugInfo { static const uint8_t CRC_LEN = 4; char _dwarf_filename[JVM_MAXPATHLEN]; uint32_t _crc; }; // Helper class to create DWARF paths when loading a DWARF file. class DwarfFilePath { private: static const uint16_t MAX_DWARF_PATH_LENGTH = JVM_MAXPATHLEN; const char* _filename; char _path[MAX_DWARF_PATH_LENGTH]; const uint32_t _crc; uint16_t _null_terminator_index; // Index for the current null terminator of the string stored in _path bool check_valid_path() const { return _path[MAX_DWARF_PATH_LENGTH - 1] == '\0'; } void update_null_terminator_index() { _null_terminator_index = checked_cast(strlen(_path)); } bool copy_to_path_index(uint16_t index_in_path, const char* src); public: DwarfFilePath(DebugInfo& debug_info) : _filename(debug_info._dwarf_filename), _crc(debug_info._crc), _null_terminator_index(0) { _path[MAX_DWARF_PATH_LENGTH - 1] = '\0'; // Ensures to have a null terminated string and not read beyond the buffer limit. } const char* path() const { return _path; } const char* filename() const { return _filename; } uint32_t crc() const { return _crc; } bool set(const char* src); bool set_filename_after_last_slash() { return set_after_last_slash(_filename); } bool set_after_last_slash(const char* src); bool append(const char* src); }; // Load the DWARF file (.debuginfo) that belongs to this file either from (checked in listed order): // - Same directory as the library file. // - User defined path in environmental variable _JVM_DWARF_PATH. // - Subdirectory .debug in same directory as the library file. // - /usr/lib/debug directory bool load_dwarf_file(); bool read_debug_info(DebugInfo* debug_info) const; bool load_dwarf_file_from_same_directory(DwarfFilePath& dwarf_file_path); bool load_dwarf_file_from_env_var_path(DwarfFilePath& dwarf_file_path); bool load_dwarf_file_from_env_path_folder(DwarfFilePath& dwarf_file_path, const char* dwarf_path_from_env, const char* folder); bool load_dwarf_file_from_debug_sub_directory(DwarfFilePath& dwarf_file_path); bool load_dwarf_file_from_usr_lib_debug(DwarfFilePath& dwarf_file_path); bool open_valid_debuginfo_file(const DwarfFilePath& dwarf_file_path); static uint32_t get_file_crc(FILE* const file); static uint gnu_debuglink_crc32(uint32_t crc, uint8_t* buf, size_t len); protected: FILE* fd() const { return _file; } // Read the section header of section 'name'. bool read_section_header(const char* name, Elf_Shdr& hdr) const; bool is_valid_dwarf_file() const; public: // For whitebox test static bool _do_not_cache_elf_section; }; /* * This class parses and reads filename and line number information from an associated .debuginfo file that belongs to * this ELF file or directly from this ELF file if there is no separate .debuginfo file. The debug info is written by GCC * in DWARF - a standardized debugging data format. There are special sections where the DWARF info is written to. These * sections can either be put into the same ELF file or a separate .debuginfo file. For simplicity, when referring to the * "DWARF file" or the ".debuginfo file" we just mean the file that contains the required DWARF sections. The current version * of GCC uses DWARF version 4 as default which is defined in the official standard: http://www.dwarfstd.org/doc/DWARF4.pdf. * This class is able to parse 32-bit DWARF version 4 for 32 and 64-bit Linux builds. GCC does not emit 64-bit DWARF and * therefore is not supported by this parser. For some reason, GCC emits DWARF version 3 for the .debug_line section as a * default. This parser was therefore adapted to support DWARF version 3 and 4 for the .debug_line section. Apart from that, * other DWARF versions, especially the newest version 5, are not (yet) supported. * * Description of used DWARF file sections: * - .debug_aranges: A table that consists of sets of variable length entries, each set describing the portion of the * program's address space that is covered by a single compilation unit. In other words, the entries * describe a mapping between addresses and compilation units. * - .debug_info: The core DWARF data containing DWARF Information Entries (DIEs). Each DIE consists of a tag and a * series of attributes. Each (normal) compilation unit is represented by a DIE with the tag * DW_TAG_compile_unit and contains children. For our purposes, we are only interested in this DIE to * get to the .debug_line section. We do not care about the children. This parser currently only * supports normal compilation units and no partial compilation or type units. * - .debug_abbrev: Represents abbreviation tables for all compilation units. A table for a specific compilation unit * consists of a series of abbreviation declarations. Each declaration specifies a tag and attributes * for a DIE. The DIEs from the compilation units in the .debug_info section need the abbreviation table * to decode their attributes (their meaning and size). * - .debug_line: Contains filename and line number information for each compilation unit. To get the information, a * state machine needs to be executed which generates a matrix. Each row of this matrix describes the * filename and line number (among other information) for a specific offset in the associated ELF library * file. The state machine is executed until the row for the requested offset is found. The filename and * line number information can then be fetched with the current register values of the state machine. * * Algorithm * --------- * Given: Offset into the ELF file library. * Return: Filename and line number for this offset. * (1) First, the path to the .debuginfo DWARF file is found by inspecting the .gnu_debuglink section of the library file. * The DWARF file is then opened by calling the constructor of this class. Once this is done, the processing of the * DWARF file is initiated by calling find_filename_and_line_number(). * (2) Find the compilation unit offset by reading entries from the section .debug_aranges, which contain address range * descriptors, until we find the correct descriptor that includes the library offset. * (3) Find the .debug_line offset for the line number information program from the .debug_info section: * (a) Parse the compilation unit header from the .debug_info section at the offset obtained by (2). * (b) Read the debug_abbrev_offset into the .debug_abbrev section that belongs to this compilation unit from the * header obtained in (3a). * (c) Read the abbreviation code that immediately follows the compilation unit header from (3a) which is needed to * find the correct entry in the .debug_abbrev section. * (d) Find the correct entry in the abbreviation table in the .debug_abbrev section by starting to parse entries at * the debug_abbrev_offset from (3b) until we find the correct one matching the abbreviation code from (3c). * (e) Read the specified attributes of the abbreviation entry from (3d) from the compilation unit (in the .debug_info * section) until we find the attribute DW_AT_stmt_list. This attributes represents an offset into the .debug_line * section which contains the line number program information to get the filename and the line number. * (4) Find the filename and line number belonging to the given library offset by running the line number program state * machine with its registers. This creates a matrix where each row stores information for specific addresses (library * offsets). The state machine executes different opcodes which modify the state machine registers. Certain opcodes * will add a new row to the matrix by taking the current values of state machine registers. As soon as the correct * matrix row matching the library offset is found, we can read the line number from the line register of the state * machine and parse the filename from the line number program header with the given file index from the file register * of the state machine. * * More details about the different phases can be found at the associated classes and methods. A visualization of the * algorithm inside the different sections can be found in the class comments for DebugAranges, DebugAbbrev and * LineNumberProgram further down in this file. * * Available (develop) log levels (-XX:TraceDwarfLevel=[1,4]) which are only present in debug builds. Each level prints * all the logs of the previous levels and adds some more fine-grained logging: * - Level 1 (summary + errors): * - Prints the path of parsed DWARF file together with the resulting source information. * - Prints all errors. * - Level 2 (info): * - Prints the found offsets of all DWARF sections * - Level 3 (debug): * - Prints the results of the steps (1) - (4) together with the generated line information matrix. * - Level 4 (trace): * - Complete information about intermediate states/results when parsing the DWARF file. */ class DwarfFile : public ElfFile { static constexpr uint8_t ADDRESS_SIZE = NOT_LP64(4) LP64_ONLY(8); // We only support 32-bit DWARF (emitted by GCC) which uses 32-bit values for DWARF section lengths and offsets // relative to the beginning of a section. static constexpr uint8_t DWARF_SECTION_OFFSET_SIZE = 4; class MarkedDwarfFileReader : public MarkedFileReader { private: long _current_pos; long _max_pos; // Used to guarantee that we stop reading in case we reached the end of a section. bool read_leb128(uint64_t* result, int8_t check_size, bool is_signed); public: MarkedDwarfFileReader(FILE* const fd) : MarkedFileReader(fd), _current_pos(-1), _max_pos(-1) {} virtual bool set_position(long new_pos); long get_position() const { return _current_pos; } void set_max_pos(long max_pos) { _max_pos = max_pos; } // Have we reached the limit of maximally allowable bytes to read? Used to ensure to stop reading when a section ends. bool has_bytes_left() const; // Call this if another file reader has changed the position of the same file handle. bool update_to_stored_position(); // Must be called to restore the old position before this file reader changed it with update_to_stored_position(). bool reset_to_previous_position(); bool move_position(long offset); bool read_byte(void* result); bool read_word(uint16_t* result); bool read_dword(uint32_t* result); bool read_qword(uint64_t* result); bool read_uleb128_ignore(int8_t check_size = -1); bool read_uleb128(uint64_t* result, int8_t check_size = -1); bool read_sleb128(int64_t* result, int8_t check_size = -1); // Reads 4 bytes for 32-bit and 8 bytes for 64-bit builds. bool read_address_sized(uintptr_t* result); bool read_string(char* result = nullptr, size_t result_len = 0); bool read_non_null_char(char* result); }; // (2) Processing the .debug_aranges section to find the compilation unit which covers offset_in_library. // This is specified in section 6.1.2 of the DWARF 4 spec. // // Structure of .debug_aranges: // Section Header // % Table of variable length sets describing the address space covered by a compilation unit // % Set 1 // ... // % Set i: // % Set header // ... // debug_info_offset -> offset to compilation unit // % Series of address range descriptors [beginning_address, range_length]: // % Descriptor 1 // ... // % Descriptor j: // beginning_address <= offset_in_library < beginning_address + range_length? // => Found the correct set covering offset_in_library. Take debug_info_offset from the set header to get // to the correct compilation unit in .debug_info. class DebugAranges { // The header is defined in section 6.1.2 of the DWARF 4 spec. struct DebugArangesSetHeader { // The total length of all of the entries for that set, not including the length field itself. uint32_t _unit_length; // This number is specific to the address lookup table and is independent of the DWARF version number. uint16_t _version; // The offset from the beginning of the .debug_info or .debug_types section of the compilation unit header referenced // by the set. In this parser we only use it as offset into .debug_info. This must be 4 bytes for 32-bit DWARF. uint32_t _debug_info_offset; // The size of an address in bytes on the target architecture, 4 bytes for 32-bit and 8 bytes for 64-bit Linux builds. uint8_t _address_size; // The size of a segment selector in bytes on the target architecture. This should be 0. uint8_t _segment_size; }; // Address descriptor defining a range that is covered by a compilation unit. It is defined in section 6.1.2 after // the set header in the DWARF 4 spec. struct AddressDescriptor { uintptr_t beginning_address = 0; uintptr_t range_length = 0; }; DwarfFile* _dwarf_file; MarkedDwarfFileReader _reader; uintptr_t _section_start_address; // a calculated end position long _entry_end; bool read_section_header(); bool read_set_header(DebugArangesSetHeader& header); bool read_address_descriptors(const DwarfFile::DebugAranges::DebugArangesSetHeader& header, uint32_t offset_in_library, bool& found_matching_set); bool read_address_descriptor(AddressDescriptor& descriptor); static bool does_match_offset(uint32_t offset_in_library, const AddressDescriptor& descriptor) ; bool is_terminating_entry(const DwarfFile::DebugAranges::DebugArangesSetHeader& header, const AddressDescriptor& descriptor); public: DebugAranges(DwarfFile* dwarf_file) : _dwarf_file(dwarf_file), _reader(dwarf_file->fd()), _section_start_address(0), _entry_end(0) {} bool find_compilation_unit_offset(uint32_t offset_in_library, uint32_t* compilation_unit_offset); }; // (3a-c,e) The compilation unit is read from the .debug_info section. The structure of .debug_info is shown in the // comments of class DebugAbbrev. class CompilationUnit { // Attribute form encodings from Figure 21 in section 7.5 of the DWARF 4 spec. static constexpr uint8_t DW_FORM_addr = 0x01; // address static constexpr uint8_t DW_FORM_block2 = 0x03; // block static constexpr uint8_t DW_FORM_block4 = 0x04; // block static constexpr uint8_t DW_FORM_data2 = 0x05; // constant static constexpr uint8_t DW_FORM_data4 = 0x06; // constant static constexpr uint8_t DW_FORM_data8 = 0x07; // constant static constexpr uint8_t DW_FORM_string = 0x08; // string static constexpr uint8_t DW_FORM_block = 0x09; // block static constexpr uint8_t DW_FORM_block1 = 0x0a; // block static constexpr uint8_t DW_FORM_data1 = 0x0b; // constant static constexpr uint8_t DW_FORM_flag = 0x0c; // flag static constexpr uint8_t DW_FORM_sdata = 0x0d; // constant static constexpr uint8_t DW_FORM_strp = 0x0e; // string static constexpr uint8_t DW_FORM_udata = 0x0f; // constant static constexpr uint8_t DW_FORM_ref_addr = 0x10; // reference0; static constexpr uint8_t DW_FORM_ref1 = 0x11; // reference static constexpr uint8_t DW_FORM_ref2 = 0x12; // reference static constexpr uint8_t DW_FORM_ref4 = 0x13; // reference static constexpr uint8_t DW_FORM_ref8 = 0x14; // reference static constexpr uint8_t DW_FORM_ref_udata = 0x15; // reference static constexpr uint8_t DW_FORM_indirect = 0x16; // see Section 7.5.3 static constexpr uint8_t DW_FORM_sec_offset = 0x17; // lineptr, loclistptr, macptr, rangelistptr static constexpr uint8_t DW_FORM_exprloc = 0x18;// exprloc static constexpr uint8_t DW_FORM_flag_present = 0x19; // flag static constexpr uint8_t DW_FORM_ref_sig8 = 0x20; // reference // The header is defined in section 7.5.1.1 of the DWARF 4 spec. struct CompilationUnitHeader { // The length of the .debug_info contribution for that compilation unit, not including the length field itself. uint32_t _unit_length; // The version of the DWARF information for the compilation unit. The value in this field is 4 for DWARF 4. uint16_t _version; // The offset into the .debug_abbrev section. This offset associates the compilation unit with a particular set of // debugging information entry abbreviations. uint32_t _debug_abbrev_offset; // The size in bytes of an address on the target architecture, 4 bytes for 32-bit and 8 bytes for 64-bit Linux builds. uint8_t _address_size; }; DwarfFile* _dwarf_file; MarkedDwarfFileReader _reader; CompilationUnitHeader _header; const uint32_t _compilation_unit_offset; // Result of a request initiated by find_debug_line_offset(). uint32_t _debug_line_offset; bool read_header(); public: CompilationUnit(DwarfFile* dwarf_file, uint32_t compilation_unit_offset) : _dwarf_file(dwarf_file), _reader(dwarf_file->fd()), _compilation_unit_offset(compilation_unit_offset), _debug_line_offset(0) {} bool find_debug_line_offset(uint32_t* debug_line_offset); bool read_attribute_value(uint64_t attribute_form, bool is_DW_AT_stmt_list_attribute); }; // (3d) Read from the .debug_abbrev section at the debug_abbrev_offset specified by the compilation unit header. // // The interplay between the .debug_info and .debug_abbrev sections is more complex. The following visualization of the structure // of both sections support the comments found in the parsing steps of the CompilationUnit and DebugAbbrev class. // // Structure of .debug_abbrev: // Section Header // % Series of abbreviation tables // % Abbreviation table 1 // ... // % Abbreviation table for compilation unit at debug_abbrev_offset: // % Series of declarations: // % Declaration 1: // abbreviation code // tag // DW_CHILDREN_yes/no // % Series of attribute specifications // % Attribute specification 1: // attribute name // attribute form // ... // % Last attribute specification: // 0 // 0 // ... // % Declaration i: // Abbrev code read from compilation unit [AC] // DW_TAG_compile_unit // DW_CHILDREN_yes // % Series of attribute specifications // % Attribute specification 1 [AS1] // ... // % Attribute specification j [ASj]: // DW_AT_stmt_list // DW_FORM_sec_offset // // // Structure of .debug_info: // Section Header // % Series of compilation units // % Compilation unit 1 // ... // % Compilation unit i for library offset fetched from .debug_aranges: // % Compilation unit header: // ... // debug_abbrev_offset -> offset for abbreviation table in .debug_abbrev for this compilation unit // ... // Abbrev code -> used in .debug_abbrev to find the correct declaration [AC] // % Series of attribute values // Attribute value 1 (in the format defined by attribute specification 1 [AS1]) // ... // Attribute value j (in the format defined by attribute specification j [ASj]): // => Specifies Offset to line number program for this compilation unit in .debug_line class DebugAbbrev { struct AbbreviationDeclaration { uint64_t _abbrev_code; uint64_t _tag; uint8_t _has_children; }; struct AttributeSpecification { uint64_t _name; uint64_t _form; }; // Tag encoding from Figure 18 in section 7.5 of the DWARF 4 spec. static constexpr uint8_t DW_TAG_compile_unit = 0x11; // Child determination encoding from Figure 19 in section 7.5 of the DWARF 4 spec. static constexpr uint8_t DW_CHILDREN_yes = 0x01; // Attribute encoding from Figure 20 in section 7.5 of the DWARF 4 spec. static constexpr uint8_t DW_AT_stmt_list = 0x10; /* There is no specific header for this section */ DwarfFile* _dwarf_file; MarkedDwarfFileReader _reader; CompilationUnit* _compilation_unit; // Need to read from compilation unit while parsing the entries in .debug_abbrev. // Result field of a request uint32_t* _debug_line_offset; bool read_declaration(AbbreviationDeclaration& declaration); static bool is_wrong_or_unsupported_format(const AbbreviationDeclaration& declaration); bool read_attribute_specifications(bool is_DW_TAG_compile_unit); bool read_attribute_specification(AttributeSpecification& specification); static bool is_terminating_specification(const AttributeSpecification& attribute_specification) ; public: DebugAbbrev(DwarfFile* dwarf_file, CompilationUnit* compilation_unit) : _dwarf_file(dwarf_file), _reader(_dwarf_file->fd()), _compilation_unit(compilation_unit), _debug_line_offset(nullptr) {} bool read_section_header(uint32_t debug_abbrev_offset); bool find_debug_line_offset(uint64_t abbrev_code); }; // (4) The line number program for the compilation unit at the offset of the .debug_line obtained by (3). // For some reason, earlier GCC versions emit the line number program in DWARF 2 or 3 format even though the // default is DWARF 4. It also mixes the standards (see comments in the parsing code). // // Therefore, this class supports DWARF 2, 3 and 4 parsing as specified in section 6.2 of the DWARF specs. // The parsing of DWARF 2 is already covered by the parsing of DWARF 3 as they use the shared opcodes in the same way. // The parsing of DWARF 4, however, needs some adaptation as it consumes more data for some shared opcodes. // // DWARF 2 standard: https://dwarfstd.org/doc/dwarf-2.0.0.pdf // DWARF 3 standard: https://dwarfstd.org/doc/Dwarf3.pdf // // // Structure of .debug_ling: // Section Header // % Series of line number program entries for each compilation unit // % Line number program 1 // ... // % Line number program i for our compilation unit: // % Line program header unit header: // ... // version -> currently emits version 3 by default // ... // file_name -> sequence of file names // % Sequence of opcodes as part of the line number program to build the line number information matrix: // % Format of matrix: [offset, line, directory_index, file_index] // % Line 1 // ... // % Line j: // [offset matching offset_in_library, line, directory_index, file_index] // => Get line number + look up file_index in file_name list (pick file_index'th string) class LineNumberProgram { // Standard opcodes for the line number program defined in section 6.2.5.2 of the DWARF 4 spec. static constexpr uint8_t DW_LNS_copy = 1; static constexpr uint8_t DW_LNS_advance_pc = 2; static constexpr uint8_t DW_LNS_advance_line = 3; static constexpr uint8_t DW_LNS_set_file = 4; static constexpr uint8_t DW_LNS_set_column = 5; static constexpr uint8_t DW_LNS_negate_stmt = 6; static constexpr uint8_t DW_LNS_set_basic_block = 7; static constexpr uint8_t DW_LNS_const_add_pc = 8; static constexpr uint8_t DW_LNS_fixed_advance_pc = 9; static constexpr uint8_t DW_LNS_set_prologue_end = 10; // Introduced with DWARF 3 static constexpr uint8_t DW_LNS_set_epilogue_begin = 11; // Introduced with DWARF 3 static constexpr uint8_t DW_LNS_set_isa = 12; // Introduced with DWARF 3 // Extended opcodes for the line number program defined in section 6.2.5.2 of the DWARF 4 spec. static constexpr uint8_t DW_LNE_end_sequence = 1; static constexpr uint8_t DW_LNE_set_address = 2; static constexpr uint8_t DW_LNE_define_file = 3; static constexpr uint8_t DW_LNE_set_discriminator = 4; // Introduced with DWARF 4 static constexpr const char* overflow_filename = ""; static constexpr const char minimal_overflow_filename = 'L'; // The header is defined in section 6.2.4 of the DWARF 4 spec. struct LineNumberProgramHeader { // The size in bytes of the line number information for this compilation unit, not including the unit_length // field itself. 32-bit DWARF uses 4 bytes. uint32_t _unit_length; // The version of the DWARF information for the line number program unit. The value in this field should be 4 for // DWARF 4 and version 3 as used for DWARF 3. uint16_t _version; // The number of bytes following the header_length field to the beginning of the first byte of the line number // program itself. 32-bit DWARF uses 4 bytes. uint32_t _header_length; // The size in bytes of the smallest target machine instruction. Line number program opcodes that alter the address // and op_index registers use this and maximum_operations_per_instruction in their calculations. uint8_t _minimum_instruction_length; // The maximum number of individual operations that may be encoded in an instruction. Line number program opcodes // that alter the address and op_index registers use this and minimum_instruction_length in their calculations. // For non-VLIW architectures, this field is 1, the op_index register is always 0, and the operation pointer is // simply the address register. This is only used with DWARF 4. uint8_t _maximum_operations_per_instruction; // The initial value of the is_stmt register. uint8_t _default_is_stmt; // This parameter affects the meaning of the special opcodes. int8_t _line_base; // This parameter affects the meaning of the special opcodes. uint8_t _line_range; // The number assigned to the first special opcode. uint8_t _opcode_base; // This array specifies the number of LEB128 operands for each of the standard opcodes. The first element of the // array corresponds to the opcode whose value is 1, and the last element corresponds to the opcode whose value is // opcode_base-1. DWARF 2 uses 9 standard opcodes while DWARF 3 and 4 use 12. uint8_t _standard_opcode_lengths[12]; /* * The following fields are not part of the real header and are only used for the implementation. */ // Offset where the filename strings are starting in header. long _file_names_offset; // _header_length only specifies the number of bytes following the _header_length field. It does not include // the size of _unit_length, _version and _header_length itself. This constant represents the number of missing // bytes to get the real size of the header: // sizeof(_unit_length) + sizeof(_version) + sizeof(_header_length) = 4 + 2 + 4 = 10 static constexpr uint8_t HEADER_DESCRIPTION_BYTES = 10; }; // The line number program state consists of several registers that hold the current state of the line number program // state machine. The state/different state registers are defined in section 6.2.2 of the DWARF 4 spec. Most of these // fields (state registers) are not used to get the filename and the line number information. struct LineNumberProgramState : public CHeapObj { // The program-counter value corresponding to a machine instruction generated by the compiler. // 4 bytes on 32-bit and 8 bytes on 64-bit. uintptr_t _address; // The index of an operation within a VLIW instruction. The index of the first operation is 0. For non-VLIW // architectures, this register will always be 0. // The address and op_index registers, taken together, form an operation pointer that can reference any // individual operation with the instruction stream. This field was introduced with DWARF 4. uint32_t _op_index; // The identity of the source file corresponding to a machine instruction. uint32_t _file; // A source line number. Lines are numbered beginning at 1. The compiler may emit the value 0 in cases where an // instruction cannot be attributed to any source line. uint32_t _line; // A column number within a source line. Columns are numbered beginning at 1. The value 0 is reserved to indicate // that a statement begins at the "left edge" of the line. uint32_t _column; // Indicates that the current instruction is a recommended breakpoint location. bool _is_stmt; // Indicates that the current instruction is the beginning of a basic block. bool _basic_block; // Indicates that the current address is that of the first byte after the end of a sequence of target machine // instructions. end_sequence terminates a sequence of lines. bool _end_sequence; // Indicates that the current address is one (of possibly many) where execution should be suspended for an entry // breakpoint of a function. This field was introduced with DWARF 3. bool _prologue_end; // Indicates that the current address is one (of possibly many) where execution should be suspended for an exit // breakpoint of a function. This field was introduced with DWARF 3. bool _epilogue_begin; // Encodes the applicable instruction set architecture for the current instruction. // This field was introduced with DWARF 3. uint32_t _isa; // Identifies the block to which the current instruction belongs. This field was introduced with DWARF 4. uint32_t _discriminator; /* * Additional fields which are not part of the actual state as described in DWARF spec. */ // Header fields // Specifies which DWARF version is used in the .debug_line section. Supported version: DWARF 2, 3, and 4. const uint16_t _dwarf_version; const bool _initial_is_stmt; // Implementation specific fields bool _append_row; bool _do_reset; bool _first_entry_in_sequence; bool _can_sequence_match_offset; bool _found_match; LineNumberProgramState(const LineNumberProgramHeader& header) : _is_stmt(header._default_is_stmt != 0), _dwarf_version(header._version), _initial_is_stmt(header._default_is_stmt != 0), _found_match(false) { reset_fields(); } void reset_fields(); // Defined in section 6.2.5.1 of the DWARF spec 4. add_to_address_register() must always be executed before set_index_register. void add_to_address_register(uint32_t operation_advance, const LineNumberProgramHeader& header); void set_index_register(uint32_t operation_advance, const LineNumberProgramHeader& header); }; DwarfFile* _dwarf_file; MarkedDwarfFileReader _reader; LineNumberProgramHeader _header; LineNumberProgramState* _state; const uint32_t _offset_in_library; const uint64_t _debug_line_offset; bool _is_pc_after_call; bool read_header(); bool run_line_number_program(char* filename, size_t filename_len, int* line); bool apply_opcode(); bool apply_extended_opcode(); bool apply_standard_opcode(uint8_t opcode); void apply_special_opcode(uint8_t opcode); bool does_offset_match_entry(uintptr_t previous_address, uint32_t previous_file, uint32_t previous_line); void print_and_store_prev_entry(uint32_t previous_file, uint32_t previous_line); bool get_filename_from_header(uint32_t file_index, char* filename, size_t filename_len); bool read_filename(char* filename, size_t filename_len); static void write_filename_for_overflow(char* filename, size_t filename_len) ; public: LineNumberProgram(DwarfFile* dwarf_file, uint32_t offset_in_library, uint64_t debug_line_offset, bool is_pc_after_call) : _dwarf_file(dwarf_file), _reader(dwarf_file->fd()), _offset_in_library(offset_in_library), _debug_line_offset(debug_line_offset), _is_pc_after_call(is_pc_after_call) {} ~LineNumberProgram() { delete _state; } bool find_filename_and_line_number(char* filename, size_t filename_len, int* line); }; public: DwarfFile(const char* filepath) : ElfFile(filepath) {} /* * Starting point of reading line number and filename information from the DWARF file. * * Given: Offset into the ELF library file, a filename buffer of size filename_size, a line number pointer. * Return: True: The filename is set in the 'filename' buffer and the line number at the address pointed to by 'line'. * False: Something went wrong either while reading from the file or during parsing due to an unexpected format. * This could happen if the DWARF file is in an unsupported or wrong format. * * More details about the different phases can be found at the associated methods. */ bool get_filename_and_line_number(uint32_t offset_in_library, char* filename, size_t filename_len, int* line, bool is_pc_after_call); }; #endif // !_WINDOWS && !__APPLE__ #endif // SHARE_UTILITIES_ELFFILE_HPP