// object.h -- support for an object file for linking in gold -*- C++ -*- // Copyright 2006, 2007, 2008, 2009 Free Software Foundation, Inc. // Written by Ian Lance Taylor . // 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_OBJECT_H #define GOLD_OBJECT_H #include #include #include "elfcpp.h" #include "elfcpp_file.h" #include "fileread.h" #include "target.h" namespace gold { class General_options; class Task; class Cref; class Archive; class Layout; class Output_section; class Output_file; class Output_symtab_xindex; class Pluginobj; class Dynobj; class Object_merge_map; class Relocatable_relocs; class Symbols_data; template class Stringpool_template; // Data to pass from read_symbols() to add_symbols(). struct Read_symbols_data { // Section headers. File_view* section_headers; // Section names. File_view* section_names; // Size of section name data in bytes. section_size_type section_names_size; // Symbol data. File_view* symbols; // Size of symbol data in bytes. section_size_type symbols_size; // Offset of external symbols within symbol data. This structure // sometimes contains only external symbols, in which case this will // be zero. Sometimes it contains all symbols. section_offset_type external_symbols_offset; // Symbol names. File_view* symbol_names; // Size of symbol name data in bytes. section_size_type symbol_names_size; // Version information. This is only used on dynamic objects. // Version symbol data (from SHT_GNU_versym section). File_view* versym; section_size_type versym_size; // Version definition data (from SHT_GNU_verdef section). File_view* verdef; section_size_type verdef_size; unsigned int verdef_info; // Needed version data (from SHT_GNU_verneed section). File_view* verneed; section_size_type verneed_size; unsigned int verneed_info; }; // Information used to print error messages. struct Symbol_location_info { std::string source_file; std::string enclosing_symbol_name; int line_number; }; // Data about a single relocation section. This is read in // read_relocs and processed in scan_relocs. struct Section_relocs { // Index of reloc section. unsigned int reloc_shndx; // Index of section that relocs apply to. unsigned int data_shndx; // Contents of reloc section. File_view* contents; // Reloc section type. unsigned int sh_type; // Number of reloc entries. size_t reloc_count; // Output section. Output_section* output_section; // Whether this section has special handling for offsets. bool needs_special_offset_handling; // Whether the data section is allocated (has the SHF_ALLOC flag set). bool is_data_section_allocated; }; // Relocations in an object file. This is read in read_relocs and // processed in scan_relocs. struct Read_relocs_data { typedef std::vector Relocs_list; // The relocations. Relocs_list relocs; // The local symbols. File_view* local_symbols; }; // The Xindex class manages section indexes for objects with more than // 0xff00 sections. class Xindex { public: Xindex(int large_shndx_offset) : large_shndx_offset_(large_shndx_offset), symtab_xindex_() { } // Initialize the symtab_xindex_ array, given the object and the // section index of the symbol table to use. template void initialize_symtab_xindex(Object*, unsigned int symtab_shndx); // Read in the symtab_xindex_ array, given its section index. // PSHDRS may optionally point to the section headers. template void read_symtab_xindex(Object*, unsigned int xindex_shndx, const unsigned char* pshdrs); // Symbol SYMNDX in OBJECT has a section of SHN_XINDEX; return the // real section index. unsigned int sym_xindex_to_shndx(Object* object, unsigned int symndx); private: // The type of the array giving the real section index for symbols // whose st_shndx field holds SHN_XINDEX. typedef std::vector Symtab_xindex; // Adjust a section index if necessary. This should only be called // for ordinary section indexes. unsigned int adjust_shndx(unsigned int shndx) { if (shndx >= elfcpp::SHN_LORESERVE) shndx += this->large_shndx_offset_; return shndx; } // Adjust to apply to large section indexes. int large_shndx_offset_; // The data from the SHT_SYMTAB_SHNDX section. Symtab_xindex symtab_xindex_; }; // Object is an abstract base class which represents either a 32-bit // or a 64-bit input object. This can be a regular object file // (ET_REL) or a shared object (ET_DYN). class Object { public: // NAME is the name of the object as we would report it to the user // (e.g., libfoo.a(bar.o) if this is in an archive. INPUT_FILE is // used to read the file. OFFSET is the offset within the input // file--0 for a .o or .so file, something else for a .a file. Object(const std::string& name, Input_file* input_file, bool is_dynamic, off_t offset = 0) : name_(name), input_file_(input_file), offset_(offset), shnum_(-1U), is_dynamic_(is_dynamic), xindex_(NULL), no_export_(false) { input_file->file().add_object(); } virtual ~Object() { this->input_file_->file().remove_object(); } // Return the name of the object as we would report it to the tuser. const std::string& name() const { return this->name_; } // Get the offset into the file. off_t offset() const { return this->offset_; } // Return whether this is a dynamic object. bool is_dynamic() const { return this->is_dynamic_; } // Returns NULL for Objects that are not plugin objects. This method // is overridden in the Pluginobj class. Pluginobj* pluginobj() { return this->do_pluginobj(); } // Get the file. We pass on const-ness. Input_file* input_file() { return this->input_file_; } const Input_file* input_file() const { return this->input_file_; } // Lock the underlying file. void lock(const Task* t) { this->input_file()->file().lock(t); } // Unlock the underlying file. void unlock(const Task* t) { this->input_file()->file().unlock(t); } // Return whether the underlying file is locked. bool is_locked() const { return this->input_file()->file().is_locked(); } // Return the token, so that the task can be queued. Task_token* token() { return this->input_file()->file().token(); } // Release the underlying file. void release() { this->input_file_->file().release(); } // Return whether we should just read symbols from this file. bool just_symbols() const { return this->input_file()->just_symbols(); } // Get the number of sections. unsigned int shnum() const { return this->shnum_; } // Return a view of the contents of a section. Set *PLEN to the // size. CACHE is a hint as in File_read::get_view. const unsigned char* section_contents(unsigned int shndx, section_size_type* plen, bool cache); // Adjust a symbol's section index as needed. SYMNDX is the index // of the symbol and SHNDX is the symbol's section from // get_st_shndx. This returns the section index. It sets // *IS_ORDINARY to indicate whether this is a normal section index, // rather than a special code between SHN_LORESERVE and // SHN_HIRESERVE. unsigned int adjust_sym_shndx(unsigned int symndx, unsigned int shndx, bool* is_ordinary) { if (shndx < elfcpp::SHN_LORESERVE) *is_ordinary = true; else if (shndx == elfcpp::SHN_XINDEX) { if (this->xindex_ == NULL) this->xindex_ = this->do_initialize_xindex(); shndx = this->xindex_->sym_xindex_to_shndx(this, symndx); *is_ordinary = true; } else *is_ordinary = false; return shndx; } // Return the size of a section given a section index. uint64_t section_size(unsigned int shndx) { return this->do_section_size(shndx); } // Return the name of a section given a section index. std::string section_name(unsigned int shndx) { return this->do_section_name(shndx); } // Return the section flags given a section index. uint64_t section_flags(unsigned int shndx) { return this->do_section_flags(shndx); } // Return the section entsize given a section index. uint64_t section_entsize(unsigned int shndx) { return this->do_section_entsize(shndx); } // Return the section address given a section index. uint64_t section_address(unsigned int shndx) { return this->do_section_address(shndx); } // Return the section type given a section index. unsigned int section_type(unsigned int shndx) { return this->do_section_type(shndx); } // Return the section link field given a section index. unsigned int section_link(unsigned int shndx) { return this->do_section_link(shndx); } // Return the section info field given a section index. unsigned int section_info(unsigned int shndx) { return this->do_section_info(shndx); } // Return the required section alignment given a section index. uint64_t section_addralign(unsigned int shndx) { return this->do_section_addralign(shndx); } // Read the symbol information. void read_symbols(Read_symbols_data* sd) { return this->do_read_symbols(sd); } // Pass sections which should be included in the link to the Layout // object, and record where the sections go in the output file. void layout(Symbol_table* symtab, Layout* layout, Read_symbols_data* sd) { this->do_layout(symtab, layout, sd); } // Add symbol information to the global symbol table. void add_symbols(Symbol_table* symtab, Read_symbols_data* sd, Layout *layout) { this->do_add_symbols(symtab, sd, layout); } // Functions and types for the elfcpp::Elf_file interface. This // permit us to use Object as the File template parameter for // elfcpp::Elf_file. // The View class is returned by view. It must support a single // method, data(). This is trivial, because get_view does what we // need. class View { public: View(const unsigned char* p) : p_(p) { } const unsigned char* data() const { return this->p_; } private: const unsigned char* p_; }; // Return a View. View view(off_t file_offset, section_size_type data_size) { return View(this->get_view(file_offset, data_size, true, true)); } // Report an error. void error(const char* format, ...) const ATTRIBUTE_PRINTF_2; // A location in the file. struct Location { off_t file_offset; off_t data_size; Location(off_t fo, section_size_type ds) : file_offset(fo), data_size(ds) { } }; // Get a View given a Location. View view(Location loc) { return View(this->get_view(loc.file_offset, loc.data_size, true, true)); } // Get a view into the underlying file. const unsigned char* get_view(off_t start, section_size_type size, bool aligned, bool cache) { return this->input_file()->file().get_view(this->offset_, start, size, aligned, cache); } // Get a lasting view into the underlying file. File_view* get_lasting_view(off_t start, section_size_type size, bool aligned, bool cache) { return this->input_file()->file().get_lasting_view(this->offset_, start, size, aligned, cache); } // Read data from the underlying file. void read(off_t start, section_size_type size, void* p) { this->input_file()->file().read(start + this->offset_, size, p); } // Read multiple data from the underlying file. void read_multiple(const File_read::Read_multiple& rm) { this->input_file()->file().read_multiple(this->offset_, rm); } // Stop caching views in the underlying file. void clear_view_cache_marks() { this->input_file()->file().clear_view_cache_marks(); } // Get the number of global symbols defined by this object, and the // number of the symbols whose final definition came from this // object. void get_global_symbol_counts(const Symbol_table* symtab, size_t* defined, size_t* used) const { this->do_get_global_symbol_counts(symtab, defined, used); } // Return whether this object was found in a system directory. bool is_in_system_directory() const { return this->input_file()->is_in_system_directory(); } // Return whether we found this object by searching a directory. bool searched_for() const { return this->input_file()->will_search_for(); } bool no_export() const { return this->no_export_; } void set_no_export(bool value) { this->no_export_ = value; } protected: // Returns NULL for Objects that are not plugin objects. This method // is overridden in the Pluginobj class. virtual Pluginobj* do_pluginobj() { return NULL; } // Read the symbols--implemented by child class. virtual void do_read_symbols(Read_symbols_data*) = 0; // Lay out sections--implemented by child class. virtual void do_layout(Symbol_table*, Layout*, Read_symbols_data*) = 0; // Add symbol information to the global symbol table--implemented by // child class. virtual void do_add_symbols(Symbol_table*, Read_symbols_data*, Layout*) = 0; // Return the location of the contents of a section. Implemented by // child class. virtual Location do_section_contents(unsigned int shndx) = 0; // Get the size of a section--implemented by child class. virtual uint64_t do_section_size(unsigned int shndx) = 0; // Get the name of a section--implemented by child class. virtual std::string do_section_name(unsigned int shndx) = 0; // Get section flags--implemented by child class. virtual uint64_t do_section_flags(unsigned int shndx) = 0; // Get section entsize--implemented by child class. virtual uint64_t do_section_entsize(unsigned int shndx) = 0; // Get section address--implemented by child class. virtual uint64_t do_section_address(unsigned int shndx) = 0; // Get section type--implemented by child class. virtual unsigned int do_section_type(unsigned int shndx) = 0; // Get section link field--implemented by child class. virtual unsigned int do_section_link(unsigned int shndx) = 0; // Get section info field--implemented by child class. virtual unsigned int do_section_info(unsigned int shndx) = 0; // Get section alignment--implemented by child class. virtual uint64_t do_section_addralign(unsigned int shndx) = 0; // Return the Xindex structure to use. virtual Xindex* do_initialize_xindex() = 0; // Implement get_global_symbol_counts--implemented by child class. virtual void do_get_global_symbol_counts(const Symbol_table*, size_t*, size_t*) const = 0; // Set the number of sections. void set_shnum(int shnum) { this->shnum_ = shnum; } // Functions used by both Sized_relobj and Sized_dynobj. // Read the section data into a Read_symbols_data object. template void read_section_data(elfcpp::Elf_file*, Read_symbols_data*); // Let the child class initialize the xindex object directly. void set_xindex(Xindex* xindex) { gold_assert(this->xindex_ == NULL); this->xindex_ = xindex; } // If NAME is the name of a special .gnu.warning section, arrange // for the warning to be issued. SHNDX is the section index. // Return whether it is a warning section. bool handle_gnu_warning_section(const char* name, unsigned int shndx, Symbol_table*); private: // This class may not be copied. Object(const Object&); Object& operator=(const Object&); // Name of object as printed to user. std::string name_; // For reading the file. Input_file* input_file_; // Offset within the file--0 for an object file, non-0 for an // archive. off_t offset_; // Number of input sections. unsigned int shnum_; // Whether this is a dynamic object. bool is_dynamic_; // Many sections for objects with more than SHN_LORESERVE sections. Xindex* xindex_; // True if exclude this object from automatic symbol export. // This is used only for archive objects. bool no_export_; }; // A regular object (ET_REL). This is an abstract base class itself. // The implementation is the template class Sized_relobj. class Relobj : public Object { public: Relobj(const std::string& name, Input_file* input_file, off_t offset = 0) : Object(name, input_file, false, offset), output_sections_(), map_to_relocatable_relocs_(NULL), object_merge_map_(NULL), relocs_must_follow_section_writes_(false), sd_(NULL) { } // During garbage collection, the Read_symbols_data pass for // each object is stored as layout needs to be done after // reloc processing. Symbols_data* get_symbols_data() { return this->sd_; } // Decides which section names have to be included in the worklist // as roots. bool is_section_name_included(const char *name); void copy_symbols_data(Symbols_data* gc_sd, Read_symbols_data* sd, unsigned int section_header_size); void set_symbols_data(Symbols_data* sd) { this->sd_ = sd; } // During garbage collection, the Read_relocs pass for all objects // is done before scanning the relocs. In that case, this->rd_ is // used to store the information from Read_relocs for each object. // This data is also used to compute the list of relevant sections. Read_relocs_data* get_relocs_data() { return this->rd_; } void set_relocs_data(Read_relocs_data* rd) { this->rd_ = rd; } virtual bool is_output_section_offset_invalid(unsigned int shndx) const = 0; // Read the relocs. void read_relocs(Read_relocs_data* rd) { return this->do_read_relocs(rd); } // Process the relocs, during garbage collection only. void gc_process_relocs(const General_options& options, Symbol_table* symtab, Layout* layout, Read_relocs_data* rd) { return this->do_gc_process_relocs(options, symtab, layout, rd); } // Scan the relocs and adjust the symbol table. void scan_relocs(const General_options& options, Symbol_table* symtab, Layout* layout, Read_relocs_data* rd) { return this->do_scan_relocs(options, symtab, layout, rd); } // The number of local symbols in the input symbol table. virtual unsigned int local_symbol_count() const { return this->do_local_symbol_count(); } // Initial local symbol processing: count the number of local symbols // in the output symbol table and dynamic symbol table; add local symbol // names to *POOL and *DYNPOOL. void count_local_symbols(Stringpool_template* pool, Stringpool_template* dynpool) { return this->do_count_local_symbols(pool, dynpool); } // Set the values of the local symbols, set the output symbol table // indexes for the local variables, and set the offset where local // symbol information will be stored. Returns the new local symbol index. unsigned int finalize_local_symbols(unsigned int index, off_t off, Symbol_table* symtab) { return this->do_finalize_local_symbols(index, off, symtab); } // Set the output dynamic symbol table indexes for the local variables. unsigned int set_local_dynsym_indexes(unsigned int index) { return this->do_set_local_dynsym_indexes(index); } // Set the offset where local dynamic symbol information will be stored. unsigned int set_local_dynsym_offset(off_t off) { return this->do_set_local_dynsym_offset(off); } // Relocate the input sections and write out the local symbols. void relocate(const General_options& options, const Symbol_table* symtab, const Layout* layout, Output_file* of) { return this->do_relocate(options, symtab, layout, of); } // Return whether an input section is being included in the link. bool is_section_included(unsigned int shndx) const { gold_assert(shndx < this->output_sections_.size()); return this->output_sections_[shndx] != NULL; } // Given a section index, return the corresponding Output_section. // The return value will be NULL if the section is not included in // the link. Output_section* output_section(unsigned int shndx) const { gold_assert(shndx < this->output_sections_.size()); return this->output_sections_[shndx]; } // Given a section index, return the offset in the Output_section. // The return value will be -1U if the section is specially mapped, // such as a merge section. uint64_t output_section_offset(unsigned int shndx) const { return this->do_output_section_offset(shndx); } // Set the offset of an input section within its output section. void set_section_offset(unsigned int shndx, uint64_t off) { this->do_set_section_offset(shndx, off); } // Return true if we need to wait for output sections to be written // before we can apply relocations. This is true if the object has // any relocations for sections which require special handling, such // as the exception frame section. bool relocs_must_follow_section_writes() const { return this->relocs_must_follow_section_writes_; } // Return the object merge map. Object_merge_map* merge_map() const { return this->object_merge_map_; } // Set the object merge map. void set_merge_map(Object_merge_map* object_merge_map) { gold_assert(this->object_merge_map_ == NULL); this->object_merge_map_ = object_merge_map; } // Record the relocatable reloc info for an input reloc section. void set_relocatable_relocs(unsigned int reloc_shndx, Relocatable_relocs* rr) { gold_assert(reloc_shndx < this->shnum()); (*this->map_to_relocatable_relocs_)[reloc_shndx] = rr; } // Get the relocatable reloc info for an input reloc section. Relocatable_relocs* relocatable_relocs(unsigned int reloc_shndx) { gold_assert(reloc_shndx < this->shnum()); return (*this->map_to_relocatable_relocs_)[reloc_shndx]; } // Layout sections whose layout was deferred while waiting for // input files from a plugin. void layout_deferred_sections(Layout* layout) { this->do_layout_deferred_sections(layout); } protected: // The output section to be used for each input section, indexed by // the input section number. The output section is NULL if the // input section is to be discarded. typedef std::vector Output_sections; // Read the relocs--implemented by child class. virtual void do_read_relocs(Read_relocs_data*) = 0; // Process the relocs--implemented by child class. virtual void do_gc_process_relocs(const General_options&, Symbol_table*, Layout*, Read_relocs_data*) = 0; // Scan the relocs--implemented by child class. virtual void do_scan_relocs(const General_options&, Symbol_table*, Layout*, Read_relocs_data*) = 0; // Return the number of local symbols--implemented by child class. virtual unsigned int do_local_symbol_count() const = 0; // Count local symbols--implemented by child class. virtual void do_count_local_symbols(Stringpool_template*, Stringpool_template*) = 0; // Finalize the local symbols. Set the output symbol table indexes // for the local variables, and set the offset where local symbol // information will be stored. virtual unsigned int do_finalize_local_symbols(unsigned int, off_t, Symbol_table*) = 0; // Set the output dynamic symbol table indexes for the local variables. virtual unsigned int do_set_local_dynsym_indexes(unsigned int) = 0; // Set the offset where local dynamic symbol information will be stored. virtual unsigned int do_set_local_dynsym_offset(off_t) = 0; // Relocate the input sections and write out the local // symbols--implemented by child class. virtual void do_relocate(const General_options& options, const Symbol_table* symtab, const Layout*, Output_file* of) = 0; // Get the offset of a section--implemented by child class. virtual uint64_t do_output_section_offset(unsigned int shndx) const = 0; // Set the offset of a section--implemented by child class. virtual void do_set_section_offset(unsigned int shndx, uint64_t off) = 0; // Layout sections whose layout was deferred while waiting for // input files from a plugin--implemented by child class. virtual void do_layout_deferred_sections(Layout*) = 0; // Return the vector mapping input sections to output sections. Output_sections& output_sections() { return this->output_sections_; } const Output_sections& output_sections() const { return this->output_sections_; } // Set the size of the relocatable relocs array. void size_relocatable_relocs() { this->map_to_relocatable_relocs_ = new std::vector(this->shnum()); } // Record that we must wait for the output sections to be written // before applying relocations. void set_relocs_must_follow_section_writes() { this->relocs_must_follow_section_writes_ = true; } private: // Mapping from input sections to output section. Output_sections output_sections_; // Mapping from input section index to the information recorded for // the relocations. This is only used for a relocatable link. std::vector* map_to_relocatable_relocs_; // Mappings for merge sections. This is managed by the code in the // Merge_map class. Object_merge_map* object_merge_map_; // Whether we need to wait for output sections to be written before // we can apply relocations. bool relocs_must_follow_section_writes_; // Used to store the relocs data computed by the Read_relocs pass. // Used during garbage collection of unused sections. Read_relocs_data* rd_; // Used to store the symbols data computed by the Read_symbols pass. // Again used during garbage collection when laying out referenced // sections. gold::Symbols_data *sd_; }; // This class is used to handle relocations against a section symbol // in an SHF_MERGE section. For such a symbol, we need to know the // addend of the relocation before we can determine the final value. // The addend gives us the location in the input section, and we can // determine how it is mapped to the output section. For a // non-section symbol, we apply the addend to the final value of the // symbol; that is done in finalize_local_symbols, and does not use // this class. template class Merged_symbol_value { public: typedef typename elfcpp::Elf_types::Elf_Addr Value; // We use a hash table to map offsets in the input section to output // addresses. typedef Unordered_map Output_addresses; Merged_symbol_value(Value input_value, Value output_start_address) : input_value_(input_value), output_start_address_(output_start_address), output_addresses_() { } // Initialize the hash table. void initialize_input_to_output_map(const Relobj*, unsigned int input_shndx); // Release the hash table to save space. void free_input_to_output_map() { this->output_addresses_.clear(); } // Get the output value corresponding to an addend. The object and // input section index are passed in because the caller will have // them; otherwise we could store them here. Value value(const Relobj* object, unsigned int input_shndx, Value addend) const { // This is a relocation against a section symbol. ADDEND is the // offset in the section. The result should be the start of some // merge area. If the object file wants something else, it should // use a regular symbol rather than a section symbol. // Unfortunately, PR 6658 shows a case in which the object file // refers to the section symbol, but uses a negative ADDEND to // compensate for a PC relative reloc. We can't handle the // general case. However, we can handle the special case of a // negative addend, by assuming that it refers to the start of the // section. Of course, that means that we have to guess when // ADDEND is negative. It is normal to see a 32-bit value here // even when the template parameter size is 64, as 64-bit object // file formats have 32-bit relocations. We know this is a merge // section, so we know it has to fit into memory. So we assume // that we won't see a value larger than a large 32-bit unsigned // value. This will break objects with very very large merge // sections; they probably break in other ways anyhow. Value input_offset = this->input_value_; if (addend < 0xffffff00) { input_offset += addend; addend = 0; } typename Output_addresses::const_iterator p = this->output_addresses_.find(input_offset); if (p != this->output_addresses_.end()) return p->second + addend; return (this->value_from_output_section(object, input_shndx, input_offset) + addend); } private: // Get the output value for an input offset if we couldn't find it // in the hash table. Value value_from_output_section(const Relobj*, unsigned int input_shndx, Value input_offset) const; // The value of the section symbol in the input file. This is // normally zero, but could in principle be something else. Value input_value_; // The start address of this merged section in the output file. Value output_start_address_; // A hash table which maps offsets in the input section to output // addresses. This only maps specific offsets, not all offsets. Output_addresses output_addresses_; }; // This POD class is holds the value of a symbol. This is used for // local symbols, and for all symbols during relocation processing. // For special sections, such as SHF_MERGE sections, this calls a // function to get the final symbol value. template class Symbol_value { public: typedef typename elfcpp::Elf_types::Elf_Addr Value; Symbol_value() : output_symtab_index_(0), output_dynsym_index_(-1U), input_shndx_(0), is_ordinary_shndx_(false), is_section_symbol_(false), is_tls_symbol_(false), has_output_value_(true) { this->u_.value = 0; } // Get the value of this symbol. OBJECT is the object in which this // symbol is defined, and ADDEND is an addend to add to the value. template Value value(const Sized_relobj* object, Value addend) const { if (this->has_output_value_) return this->u_.value + addend; else { gold_assert(this->is_ordinary_shndx_); return this->u_.merged_symbol_value->value(object, this->input_shndx_, addend); } } // Set the value of this symbol in the output symbol table. void set_output_value(Value value) { this->u_.value = value; } // For a section symbol in a merged section, we need more // information. void set_merged_symbol_value(Merged_symbol_value* msv) { gold_assert(this->is_section_symbol_); this->has_output_value_ = false; this->u_.merged_symbol_value = msv; } // Initialize the input to output map for a section symbol in a // merged section. We also initialize the value of a non-section // symbol in a merged section. void initialize_input_to_output_map(const Relobj* object) { if (!this->has_output_value_) { gold_assert(this->is_section_symbol_ && this->is_ordinary_shndx_); Merged_symbol_value* msv = this->u_.merged_symbol_value; msv->initialize_input_to_output_map(object, this->input_shndx_); } } // Free the input to output map for a section symbol in a merged // section. void free_input_to_output_map() { if (!this->has_output_value_) this->u_.merged_symbol_value->free_input_to_output_map(); } // Set the value of the symbol from the input file. This is only // called by count_local_symbols, to communicate the value to // finalize_local_symbols. void set_input_value(Value value) { this->u_.value = value; } // Return the input value. This is only called by // finalize_local_symbols and (in special cases) relocate_section. Value input_value() const { return this->u_.value; } // Return whether this symbol should go into the output symbol // table. bool needs_output_symtab_entry() const { return this->output_symtab_index_ != -1U; } // Return the index in the output symbol table. unsigned int output_symtab_index() const { gold_assert(this->output_symtab_index_ != 0); return this->output_symtab_index_; } // Set the index in the output symbol table. void set_output_symtab_index(unsigned int i) { gold_assert(this->output_symtab_index_ == 0); this->output_symtab_index_ = i; } // Record that this symbol should not go into the output symbol // table. void set_no_output_symtab_entry() { gold_assert(this->output_symtab_index_ == 0); this->output_symtab_index_ = -1U; } // Set the index in the output dynamic symbol table. void set_needs_output_dynsym_entry() { gold_assert(!this->is_section_symbol()); this->output_dynsym_index_ = 0; } // Return whether this symbol should go into the output symbol // table. bool needs_output_dynsym_entry() const { return this->output_dynsym_index_ != -1U; } // Record that this symbol should go into the dynamic symbol table. void set_output_dynsym_index(unsigned int i) { gold_assert(this->output_dynsym_index_ == 0); this->output_dynsym_index_ = i; } // Return the index in the output dynamic symbol table. unsigned int output_dynsym_index() const { gold_assert(this->output_dynsym_index_ != 0 && this->output_dynsym_index_ != -1U); return this->output_dynsym_index_; } // Set the index of the input section in the input file. void set_input_shndx(unsigned int i, bool is_ordinary) { this->input_shndx_ = i; // input_shndx_ field is a bitfield, so make sure that the value // fits. gold_assert(this->input_shndx_ == i); this->is_ordinary_shndx_ = is_ordinary; } // Return the index of the input section in the input file. unsigned int input_shndx(bool* is_ordinary) const { *is_ordinary = this->is_ordinary_shndx_; return this->input_shndx_; } // Whether this is a section symbol. bool is_section_symbol() const { return this->is_section_symbol_; } // Record that this is a section symbol. void set_is_section_symbol() { gold_assert(!this->needs_output_dynsym_entry()); this->is_section_symbol_ = true; } // Record that this is a TLS symbol. void set_is_tls_symbol() { this->is_tls_symbol_ = true; } // Return TRUE if this is a TLS symbol. bool is_tls_symbol() const { return this->is_tls_symbol_; } private: // The index of this local symbol in the output symbol table. This // will be -1 if the symbol should not go into the symbol table. unsigned int output_symtab_index_; // The index of this local symbol in the dynamic symbol table. This // will be -1 if the symbol should not go into the symbol table. unsigned int output_dynsym_index_; // The section index in the input file in which this symbol is // defined. unsigned int input_shndx_ : 28; // Whether the section index is an ordinary index, not a special // value. bool is_ordinary_shndx_ : 1; // Whether this is a STT_SECTION symbol. bool is_section_symbol_ : 1; // Whether this is a STT_TLS symbol. bool is_tls_symbol_ : 1; // Whether this symbol has a value for the output file. This is // normally set to true during Layout::finalize, by // finalize_local_symbols. It will be false for a section symbol in // a merge section, as for such symbols we can not determine the // value to use in a relocation until we see the addend. bool has_output_value_ : 1; union { // This is used if has_output_value_ is true. Between // count_local_symbols and finalize_local_symbols, this is the // value in the input file. After finalize_local_symbols, it is // the value in the output file. Value value; // This is used if has_output_value_ is false. It points to the // information we need to get the value for a merge section. Merged_symbol_value* merged_symbol_value; } u_; }; // A GOT offset list. A symbol may have more than one GOT offset // (e.g., when mixing modules compiled with two different TLS models), // but will usually have at most one. GOT_TYPE identifies the type of // GOT entry; its values are specific to each target. class Got_offset_list { public: Got_offset_list() : got_type_(-1U), got_offset_(0), got_next_(NULL) { } Got_offset_list(unsigned int got_type, unsigned int got_offset) : got_type_(got_type), got_offset_(got_offset), got_next_(NULL) { } ~Got_offset_list() { if (this->got_next_ != NULL) { delete this->got_next_; this->got_next_ = NULL; } } // Initialize the fields to their default values. void init() { this->got_type_ = -1U; this->got_offset_ = 0; this->got_next_ = NULL; } // Set the offset for the GOT entry of type GOT_TYPE. void set_offset(unsigned int got_type, unsigned int got_offset) { if (this->got_type_ == -1U) { this->got_type_ = got_type; this->got_offset_ = got_offset; } else { for (Got_offset_list* g = this; g != NULL; g = g->got_next_) { if (g->got_type_ == got_type) { g->got_offset_ = got_offset; return; } } Got_offset_list* g = new Got_offset_list(got_type, got_offset); g->got_next_ = this->got_next_; this->got_next_ = g; } } // Return the offset for a GOT entry of type GOT_TYPE. unsigned int get_offset(unsigned int got_type) const { for (const Got_offset_list* g = this; g != NULL; g = g->got_next_) { if (g->got_type_ == got_type) return g->got_offset_; } return -1U; } private: unsigned int got_type_; unsigned int got_offset_; Got_offset_list* got_next_; }; // A regular object file. This is size and endian specific. template class Sized_relobj : public Relobj { public: typedef typename elfcpp::Elf_types::Elf_Addr Address; typedef std::vector Symbols; typedef std::vector > Local_values; static const Address invalid_address = static_cast
(0) - 1; Sized_relobj(const std::string& name, Input_file* input_file, off_t offset, const typename elfcpp::Ehdr&); ~Sized_relobj(); // Checks if the offset of input section SHNDX within its output // section is invalid. bool is_output_section_offset_invalid(unsigned int shndx) const { return this->get_output_section_offset(shndx) == invalid_address; } // Set up the object file based on TARGET. void setup(); // Return the number of symbols. This is only valid after // Object::add_symbols has been called. unsigned int symbol_count() const { return this->local_symbol_count_ + this->symbols_.size(); } // If SYM is the index of a global symbol in the object file's // symbol table, return the Symbol object. Otherwise, return NULL. Symbol* global_symbol(unsigned int sym) const { if (sym >= this->local_symbol_count_) { gold_assert(sym - this->local_symbol_count_ < this->symbols_.size()); return this->symbols_[sym - this->local_symbol_count_]; } return NULL; } // Return the section index of symbol SYM. Set *VALUE to its value // in the object file. Set *IS_ORDINARY if this is an ordinary // section index, not a special code between SHN_LORESERVE and // SHN_HIRESERVE. Note that for a symbol which is not defined in // this object file, this will set *VALUE to 0 and return SHN_UNDEF; // it will not return the final value of the symbol in the link. unsigned int symbol_section_and_value(unsigned int sym, Address* value, bool* is_ordinary); // Return a pointer to the Symbol_value structure which holds the // value of a local symbol. const Symbol_value* local_symbol(unsigned int sym) const { gold_assert(sym < this->local_values_.size()); return &this->local_values_[sym]; } // Return the index of local symbol SYM in the ordinary symbol // table. A value of -1U means that the symbol is not being output. unsigned int symtab_index(unsigned int sym) const { gold_assert(sym < this->local_values_.size()); return this->local_values_[sym].output_symtab_index(); } // Return the index of local symbol SYM in the dynamic symbol // table. A value of -1U means that the symbol is not being output. unsigned int dynsym_index(unsigned int sym) const { gold_assert(sym < this->local_values_.size()); return this->local_values_[sym].output_dynsym_index(); } // Return the input section index of local symbol SYM. unsigned int local_symbol_input_shndx(unsigned int sym, bool* is_ordinary) const { gold_assert(sym < this->local_values_.size()); return this->local_values_[sym].input_shndx(is_ordinary); } // Record that local symbol SYM needs a dynamic symbol entry. void set_needs_output_dynsym_entry(unsigned int sym) { gold_assert(sym < this->local_values_.size()); this->local_values_[sym].set_needs_output_dynsym_entry(); } // Return whether the local symbol SYMNDX has a GOT offset. // For TLS symbols, the GOT entry will hold its tp-relative offset. bool local_has_got_offset(unsigned int symndx, unsigned int got_type) const { Local_got_offsets::const_iterator p = this->local_got_offsets_.find(symndx); return (p != this->local_got_offsets_.end() && p->second->get_offset(got_type) != -1U); } // Return the GOT offset of the local symbol SYMNDX. unsigned int local_got_offset(unsigned int symndx, unsigned int got_type) const { Local_got_offsets::const_iterator p = this->local_got_offsets_.find(symndx); gold_assert(p != this->local_got_offsets_.end()); unsigned int off = p->second->get_offset(got_type); gold_assert(off != -1U); return off; } // Set the GOT offset of the local symbol SYMNDX to GOT_OFFSET. void set_local_got_offset(unsigned int symndx, unsigned int got_type, unsigned int got_offset) { Local_got_offsets::const_iterator p = this->local_got_offsets_.find(symndx); if (p != this->local_got_offsets_.end()) p->second->set_offset(got_type, got_offset); else { Got_offset_list* g = new Got_offset_list(got_type, got_offset); std::pair ins = this->local_got_offsets_.insert(std::make_pair(symndx, g)); gold_assert(ins.second); } } // Get the offset of input section SHNDX within its output section. // This is -1 if the input section requires a special mapping, such // as a merge section. The output section can be found in the // output_sections_ field of the parent class Relobj. Address get_output_section_offset(unsigned int shndx) const { gold_assert(shndx < this->section_offsets_.size()); return this->section_offsets_[shndx]; } // Return the name of the symbol that spans the given offset in the // specified section in this object. This is used only for error // messages and is not particularly efficient. bool get_symbol_location_info(unsigned int shndx, off_t offset, Symbol_location_info* info); // Look for a kept section corresponding to the given discarded section, // and return its output address. This is used only for relocations in // debugging sections. Address map_to_kept_section(unsigned int shndx, bool* found) const; protected: // Read the symbols. void do_read_symbols(Read_symbols_data*); // Return the number of local symbols. unsigned int do_local_symbol_count() const { return this->local_symbol_count_; } // Lay out the input sections. void do_layout(Symbol_table*, Layout*, Read_symbols_data*); // Layout sections whose layout was deferred while waiting for // input files from a plugin. void do_layout_deferred_sections(Layout*); // Add the symbols to the symbol table. void do_add_symbols(Symbol_table*, Read_symbols_data*, Layout*); // Read the relocs. void do_read_relocs(Read_relocs_data*); // Process the relocs to find list of referenced sections. Used only // during garbage collection. void do_gc_process_relocs(const General_options&, Symbol_table*, Layout*, Read_relocs_data*); // Scan the relocs and adjust the symbol table. void do_scan_relocs(const General_options&, Symbol_table*, Layout*, Read_relocs_data*); // Count the local symbols. void do_count_local_symbols(Stringpool_template*, Stringpool_template*); // Finalize the local symbols. unsigned int do_finalize_local_symbols(unsigned int, off_t, Symbol_table*); // Set the offset where local dynamic symbol information will be stored. unsigned int do_set_local_dynsym_indexes(unsigned int); // Set the offset where local dynamic symbol information will be stored. unsigned int do_set_local_dynsym_offset(off_t); // Relocate the input sections and write out the local symbols. void do_relocate(const General_options& options, const Symbol_table* symtab, const Layout*, Output_file* of); // Get the size of a section. uint64_t do_section_size(unsigned int shndx) { return this->elf_file_.section_size(shndx); } // Get the name of a section. std::string do_section_name(unsigned int shndx) { return this->elf_file_.section_name(shndx); } // Return the location of the contents of a section. Object::Location do_section_contents(unsigned int shndx) { return this->elf_file_.section_contents(shndx); } // Return section flags. uint64_t do_section_flags(unsigned int shndx); // Return section entsize. uint64_t do_section_entsize(unsigned int shndx); // Return section address. uint64_t do_section_address(unsigned int shndx) { return this->elf_file_.section_addr(shndx); } // Return section type. unsigned int do_section_type(unsigned int shndx) { return this->elf_file_.section_type(shndx); } // Return the section link field. unsigned int do_section_link(unsigned int shndx) { return this->elf_file_.section_link(shndx); } // Return the section info field. unsigned int do_section_info(unsigned int shndx) { return this->elf_file_.section_info(shndx); } // Return the section alignment. uint64_t do_section_addralign(unsigned int shndx) { return this->elf_file_.section_addralign(shndx); } // Return the Xindex structure to use. Xindex* do_initialize_xindex(); // Get symbol counts. void do_get_global_symbol_counts(const Symbol_table*, size_t*, size_t*) const; // Get the offset of a section. uint64_t do_output_section_offset(unsigned int shndx) const { Address off = this->get_output_section_offset(shndx); if (off == invalid_address) return -1ULL; return off; } // Set the offset of a section. void do_set_section_offset(unsigned int shndx, uint64_t off) { gold_assert(shndx < this->section_offsets_.size()); this->section_offsets_[shndx] = convert_types(off); } private: // For convenience. typedef Sized_relobj This; static const int ehdr_size = elfcpp::Elf_sizes::ehdr_size; static const int shdr_size = elfcpp::Elf_sizes::shdr_size; static const int sym_size = elfcpp::Elf_sizes::sym_size; typedef elfcpp::Shdr Shdr; // To keep track of discarded comdat sections, we need to map a member // section index to the object and section index of the corresponding // kept section. struct Kept_comdat_section { Kept_comdat_section(Relobj* a_object, unsigned int a_shndx) : object(a_object), shndx(a_shndx) { } Relobj* object; unsigned int shndx; }; typedef std::map Kept_comdat_section_table; // Adjust a section index if necessary. unsigned int adjust_shndx(unsigned int shndx) { if (shndx >= elfcpp::SHN_LORESERVE) shndx += this->elf_file_.large_shndx_offset(); return shndx; } // Find the SHT_SYMTAB section, given the section headers. void find_symtab(const unsigned char* pshdrs); // Return whether SHDR has the right flags for a GNU style exception // frame section. bool check_eh_frame_flags(const elfcpp::Shdr* shdr) const; // Return whether there is a section named .eh_frame which might be // a GNU style exception frame section. bool find_eh_frame(const unsigned char* pshdrs, const char* names, section_size_type names_size) const; // Whether to include a section group in the link. bool include_section_group(Symbol_table*, Layout*, unsigned int, const char*, const unsigned char*, const char *, section_size_type, std::vector*); // Whether to include a linkonce section in the link. bool include_linkonce_section(Layout*, unsigned int, const char*, const elfcpp::Shdr&); // Layout an input section. void layout_section(Layout* layout, unsigned int shndx, const char* name, typename This::Shdr& shdr, unsigned int reloc_shndx, unsigned int reloc_type); // Views and sizes when relocating. struct View_size { unsigned char* view; typename elfcpp::Elf_types::Elf_Addr address; off_t offset; section_size_type view_size; bool is_input_output_view; bool is_postprocessing_view; }; typedef std::vector Views; // Write section data to the output file. Record the views and // sizes in VIEWS for use when relocating. void write_sections(const unsigned char* pshdrs, Output_file*, Views*); // Relocate the sections in the output file. void relocate_sections(const General_options& options, const Symbol_table*, const Layout*, const unsigned char* pshdrs, Views*); // Scan the input relocations for --emit-relocs. void emit_relocs_scan(const General_options&, Symbol_table*, Layout*, const unsigned char* plocal_syms, const Read_relocs_data::Relocs_list::iterator&); // Scan the input relocations for --emit-relocs, templatized on the // type of the relocation section. template void emit_relocs_scan_reltype(const General_options&, Symbol_table*, Layout*, const unsigned char* plocal_syms, const Read_relocs_data::Relocs_list::iterator&, Relocatable_relocs*); // Emit the relocs for --emit-relocs. void emit_relocs(const Relocate_info*, unsigned int, unsigned int sh_type, const unsigned char* prelocs, size_t reloc_count, Output_section*, Address output_offset, unsigned char* view, Address address, section_size_type view_size, unsigned char* reloc_view, section_size_type reloc_view_size); // Emit the relocs for --emit-relocs, templatized on the type of the // relocation section. template void emit_relocs_reltype(const Relocate_info*, unsigned int, const unsigned char* prelocs, size_t reloc_count, Output_section*, Address output_offset, unsigned char* view, Address address, section_size_type view_size, unsigned char* reloc_view, section_size_type reloc_view_size); // Initialize input to output maps for section symbols in merged // sections. void initialize_input_to_output_maps(); // Free the input to output maps for section symbols in merged // sections. void free_input_to_output_maps(); // Write out the local symbols. void write_local_symbols(Output_file*, const Stringpool_template*, const Stringpool_template*, Output_symtab_xindex*, Output_symtab_xindex*); // Clear the local symbol information. void clear_local_symbols() { this->local_values_.clear(); this->local_got_offsets_.clear(); } // Record a mapping from discarded section SHNDX to the corresponding // kept section. void set_kept_comdat_section(unsigned int shndx, Relobj* kept_object, unsigned int kept_shndx) { Kept_comdat_section kept(kept_object, kept_shndx); this->kept_comdat_sections_.insert(std::make_pair(shndx, kept)); } // Find the kept section corresponding to the discarded section // SHNDX. Return true if found. bool get_kept_comdat_section(unsigned int shndx, Relobj** kept_object, unsigned int* kept_shndx) const { typename Kept_comdat_section_table::const_iterator p = this->kept_comdat_sections_.find(shndx); if (p == this->kept_comdat_sections_.end()) return false; *kept_object = p->second.object; *kept_shndx = p->second.shndx; return true; } // The GOT offsets of local symbols. This map also stores GOT offsets // for tp-relative offsets for TLS symbols. typedef Unordered_map Local_got_offsets; // The TLS GOT offsets of local symbols. The map stores the offsets // for either a single GOT entry that holds the module index of a TLS // symbol, or a pair of GOT entries containing the module index and // dtv-relative offset. struct Tls_got_entry { Tls_got_entry(int got_offset, bool have_pair) : got_offset_(got_offset), have_pair_(have_pair) { } int got_offset_; bool have_pair_; }; typedef Unordered_map Local_tls_got_offsets; // Saved information for sections whose layout was deferred. struct Deferred_layout { static const int shdr_size = elfcpp::Elf_sizes::shdr_size; Deferred_layout(unsigned int shndx, const char* name, const unsigned char* pshdr, unsigned int reloc_shndx, unsigned int reloc_type) : shndx_(shndx), name_(name), reloc_shndx_(reloc_shndx), reloc_type_(reloc_type) { memcpy(this->shdr_data_, pshdr, shdr_size); } unsigned int shndx_; std::string name_; unsigned int reloc_shndx_; unsigned int reloc_type_; unsigned char shdr_data_[shdr_size]; }; // General access to the ELF file. elfcpp::Elf_file elf_file_; // Index of SHT_SYMTAB section. unsigned int symtab_shndx_; // The number of local symbols. unsigned int local_symbol_count_; // The number of local symbols which go into the output file. unsigned int output_local_symbol_count_; // The number of local symbols which go into the output file's dynamic // symbol table. unsigned int output_local_dynsym_count_; // The entries in the symbol table for the external symbols. Symbols symbols_; // Number of symbols defined in object file itself. size_t defined_count_; // File offset for local symbols. off_t local_symbol_offset_; // File offset for local dynamic symbols. off_t local_dynsym_offset_; // Values of local symbols. Local_values local_values_; // GOT offsets for local non-TLS symbols, and tp-relative offsets // for TLS symbols, indexed by symbol number. Local_got_offsets local_got_offsets_; // For each input section, the offset of the input section in its // output section. This is INVALID_ADDRESS if the input section requires a // special mapping. std::vector
section_offsets_; // Table mapping discarded comdat sections to corresponding kept sections. Kept_comdat_section_table kept_comdat_sections_; // Whether this object has a GNU style .eh_frame section. bool has_eh_frame_; // If this object has a GNU style .eh_frame section that is discarded in // output, record the index here. Otherwise it is -1U. unsigned int discarded_eh_frame_shndx_; // The list of sections whose layout was deferred. std::vector deferred_layout_; }; // A class to manage the list of all objects. class Input_objects { public: Input_objects() : relobj_list_(), dynobj_list_(), sonames_(), cref_(NULL) { } // The type of the list of input relocateable objects. typedef std::vector Relobj_list; typedef Relobj_list::const_iterator Relobj_iterator; // The type of the list of input dynamic objects. typedef std::vector Dynobj_list; typedef Dynobj_list::const_iterator Dynobj_iterator; // Add an object to the list. Return true if all is well, or false // if this object should be ignored. bool add_object(Object*); // Start processing an archive. void archive_start(Archive*); // Stop processing an archive. void archive_stop(Archive*); // For each dynamic object, check whether we've seen all of its // explicit dependencies. void check_dynamic_dependencies() const; // Return whether an object was found in the system library // directory. bool found_in_system_library_directory(const Object*) const; // Print symbol counts. void print_symbol_counts(const Symbol_table*) const; // Iterate over all regular objects. Relobj_iterator relobj_begin() const { return this->relobj_list_.begin(); } Relobj_iterator relobj_end() const { return this->relobj_list_.end(); } // Iterate over all dynamic objects. Dynobj_iterator dynobj_begin() const { return this->dynobj_list_.begin(); } Dynobj_iterator dynobj_end() const { return this->dynobj_list_.end(); } // Return whether we have seen any dynamic objects. bool any_dynamic() const { return !this->dynobj_list_.empty(); } // Return the number of input objects. int number_of_input_objects() const { return this->relobj_list_.size() + this->dynobj_list_.size(); } private: Input_objects(const Input_objects&); Input_objects& operator=(const Input_objects&); // The list of ordinary objects included in the link. Relobj_list relobj_list_; // The list of dynamic objects included in the link. Dynobj_list dynobj_list_; // SONAMEs that we have seen. Unordered_set sonames_; // Manage cross-references if requested. Cref* cref_; }; // Some of the information we pass to the relocation routines. We // group this together to avoid passing a dozen different arguments. template struct Relocate_info { // Command line options. const General_options* options; // Symbol table. const Symbol_table* symtab; // Layout. const Layout* layout; // Object being relocated. Sized_relobj* object; // Section index of relocation section. unsigned int reloc_shndx; // Section index of section being relocated. unsigned int data_shndx; // Return a string showing the location of a relocation. This is // only used for error messages. std::string location(size_t relnum, off_t reloffset) const; }; // Return whether INPUT_FILE contains an ELF object start at file // offset OFFSET. This sets *START to point to a view of the start of // the file. It sets *READ_SIZE to the number of bytes in the view. extern bool is_elf_object(Input_file* input_file, off_t offset, const unsigned char** start, int *read_size); // Return an Object appropriate for the input file. P is BYTES long, // and holds the ELF header. If PUNCONFIGURED is not NULL, then if // this sees an object the linker is not configured to support, it // sets *PUNCONFIGURED to true and returns NULL without giving an // error message. extern Object* make_elf_object(const std::string& name, Input_file*, off_t offset, const unsigned char* p, section_offset_type bytes, bool* punconfigured); } // end namespace gold #endif // !defined(GOLD_OBJECT_H)