// layout.h -- lay out output file sections for gold -*- C++ -*- // Copyright (C) 2006-2014 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_LAYOUT_H #define GOLD_LAYOUT_H #include #include #include #include #include #include #include "script.h" #include "workqueue.h" #include "object.h" #include "dynobj.h" #include "stringpool.h" namespace gold { class General_options; class Incremental_inputs; class Incremental_binary; class Input_objects; class Mapfile; class Symbol_table; class Output_section_data; class Output_section; class Output_section_headers; class Output_segment_headers; class Output_file_header; class Output_segment; class Output_data; class Output_data_reloc_generic; class Output_data_dynamic; class Output_symtab_xindex; class Output_reduced_debug_abbrev_section; class Output_reduced_debug_info_section; class Eh_frame; class Gdb_index; class Target; struct Timespec; // Return TRUE if SECNAME is the name of a compressed debug section. extern bool is_compressed_debug_section(const char* secname); // Maintain a list of free space within a section, segment, or file. // Used for incremental update links. class Free_list { public: struct Free_list_node { Free_list_node(off_t start, off_t end) : start_(start), end_(end) { } off_t start_; off_t end_; }; typedef std::list::const_iterator Const_iterator; Free_list() : list_(), last_remove_(list_.begin()), extend_(false), length_(0), min_hole_(0) { } // Initialize the free list for a section of length LEN. // If EXTEND is true, free space may be allocated past the end. void init(off_t len, bool extend); // Set the minimum hole size that is allowed when allocating // from the free list. void set_min_hole_size(off_t min_hole) { this->min_hole_ = min_hole; } // Remove a chunk from the free list. void remove(off_t start, off_t end); // Allocate a chunk of space from the free list of length LEN, // with alignment ALIGN, and minimum offset MINOFF. off_t allocate(off_t len, uint64_t align, off_t minoff); // Return an iterator for the beginning of the free list. Const_iterator begin() const { return this->list_.begin(); } // Return an iterator for the end of the free list. Const_iterator end() const { return this->list_.end(); } // Dump the free list (for debugging). void dump(); // Print usage statistics. static void print_stats(); private: typedef std::list::iterator Iterator; // The free list. std::list list_; // The last node visited during a remove operation. Iterator last_remove_; // Whether we can extend past the original length. bool extend_; // The total length of the section, segment, or file. off_t length_; // The minimum hole size allowed. When allocating from the free list, // we must not leave a hole smaller than this. off_t min_hole_; // Statistics: // The total number of free lists used. static unsigned int num_lists; // The total number of free list nodes used. static unsigned int num_nodes; // The total number of calls to Free_list::remove. static unsigned int num_removes; // The total number of nodes visited during calls to Free_list::remove. static unsigned int num_remove_visits; // The total number of calls to Free_list::allocate. static unsigned int num_allocates; // The total number of nodes visited during calls to Free_list::allocate. static unsigned int num_allocate_visits; }; // This task function handles mapping the input sections to output // sections and laying them out in memory. class Layout_task_runner : public Task_function_runner { public: // OPTIONS is the command line options, INPUT_OBJECTS is the list of // input objects, SYMTAB is the symbol table, LAYOUT is the layout // object. Layout_task_runner(const General_options& options, const Input_objects* input_objects, Symbol_table* symtab, Target* target, Layout* layout, Mapfile* mapfile) : options_(options), input_objects_(input_objects), symtab_(symtab), target_(target), layout_(layout), mapfile_(mapfile) { } // Run the operation. void run(Workqueue*, const Task*); private: Layout_task_runner(const Layout_task_runner&); Layout_task_runner& operator=(const Layout_task_runner&); const General_options& options_; const Input_objects* input_objects_; Symbol_table* symtab_; Target* target_; Layout* layout_; Mapfile* mapfile_; }; // This class holds information about the comdat group or // .gnu.linkonce section that will be kept for a given signature. class Kept_section { private: // For a comdat group, we build a mapping from the name of each // section in the group to the section index and the size in object. // When we discard a group in some other object file, we use this // map to figure out which kept section the discarded section is // associated with. We then use that mapping when processing relocs // against discarded sections. struct Comdat_section_info { // The section index. unsigned int shndx; // The section size. uint64_t size; Comdat_section_info(unsigned int a_shndx, uint64_t a_size) : shndx(a_shndx), size(a_size) { } }; // Most comdat groups have only one or two sections, so we use a // std::map rather than an Unordered_map to optimize for that case // without paying too heavily for groups with more sections. typedef std::map Comdat_group; public: Kept_section() : object_(NULL), shndx_(0), is_comdat_(false), is_group_name_(false) { this->u_.linkonce_size = 0; } // We need to support copies for the signature map in the Layout // object, but we should never copy an object after it has been // marked as a comdat section. Kept_section(const Kept_section& k) : object_(k.object_), shndx_(k.shndx_), is_comdat_(false), is_group_name_(k.is_group_name_) { gold_assert(!k.is_comdat_); this->u_.linkonce_size = 0; } ~Kept_section() { if (this->is_comdat_) delete this->u_.group_sections; } // The object where this section lives. Relobj* object() const { return this->object_; } // Set the object. void set_object(Relobj* object) { gold_assert(this->object_ == NULL); this->object_ = object; } // The section index. unsigned int shndx() const { return this->shndx_; } // Set the section index. void set_shndx(unsigned int shndx) { gold_assert(this->shndx_ == 0); this->shndx_ = shndx; } // Whether this is a comdat group. bool is_comdat() const { return this->is_comdat_; } // Set that this is a comdat group. void set_is_comdat() { gold_assert(!this->is_comdat_); this->is_comdat_ = true; this->u_.group_sections = new Comdat_group(); } // Whether this is associated with the name of a group or section // rather than the symbol name derived from a linkonce section. bool is_group_name() const { return this->is_group_name_; } // Note that this represents a comdat group rather than a single // linkonce section. void set_is_group_name() { this->is_group_name_ = true; } // Add a section to the group list. void add_comdat_section(const std::string& name, unsigned int shndx, uint64_t size) { gold_assert(this->is_comdat_); Comdat_section_info sinfo(shndx, size); this->u_.group_sections->insert(std::make_pair(name, sinfo)); } // Look for a section name in the group list, and return whether it // was found. If found, returns the section index and size. bool find_comdat_section(const std::string& name, unsigned int* pshndx, uint64_t* psize) const { gold_assert(this->is_comdat_); Comdat_group::const_iterator p = this->u_.group_sections->find(name); if (p == this->u_.group_sections->end()) return false; *pshndx = p->second.shndx; *psize = p->second.size; return true; } // If there is only one section in the group list, return true, and // return the section index and size. bool find_single_comdat_section(unsigned int* pshndx, uint64_t* psize) const { gold_assert(this->is_comdat_); if (this->u_.group_sections->size() != 1) return false; Comdat_group::const_iterator p = this->u_.group_sections->begin(); *pshndx = p->second.shndx; *psize = p->second.size; return true; } // Return the size of a linkonce section. uint64_t linkonce_size() const { gold_assert(!this->is_comdat_); return this->u_.linkonce_size; } // Set the size of a linkonce section. void set_linkonce_size(uint64_t size) { gold_assert(!this->is_comdat_); this->u_.linkonce_size = size; } private: // No assignment. Kept_section& operator=(const Kept_section&); // The object containing the comdat group or .gnu.linkonce section. Relobj* object_; // Index of the group section for comdats and the section itself for // .gnu.linkonce. unsigned int shndx_; // True if this is for a comdat group rather than a .gnu.linkonce // section. bool is_comdat_; // The Kept_sections are values of a mapping, that maps names to // them. This field is true if this struct is associated with the // name of a comdat or .gnu.linkonce, false if it is associated with // the name of a symbol obtained from the .gnu.linkonce.* name // through some heuristics. bool is_group_name_; union { // If the is_comdat_ field is true, this holds a map from names of // the sections in the group to section indexes in object_ and to // section sizes. Comdat_group* group_sections; // If the is_comdat_ field is false, this holds the size of the // single section. uint64_t linkonce_size; } u_; }; // The ordering for output sections. This controls how output // sections are ordered within a PT_LOAD output segment. enum Output_section_order { // Unspecified. Used for non-load segments. Also used for the file // and segment headers. ORDER_INVALID, // The PT_INTERP section should come first, so that the dynamic // linker can pick it up quickly. ORDER_INTERP, // Loadable read-only note sections come next so that the PT_NOTE // segment is on the first page of the executable. ORDER_RO_NOTE, // Put read-only sections used by the dynamic linker early in the // executable to minimize paging. ORDER_DYNAMIC_LINKER, // Put reloc sections used by the dynamic linker after other // sections used by the dynamic linker; otherwise, objcopy and strip // get confused. ORDER_DYNAMIC_RELOCS, // Put the PLT reloc section after the other dynamic relocs; // otherwise, prelink gets confused. ORDER_DYNAMIC_PLT_RELOCS, // The .init section. ORDER_INIT, // The PLT. ORDER_PLT, // The regular text sections. ORDER_TEXT, // The .fini section. ORDER_FINI, // The read-only sections. ORDER_READONLY, // The exception frame sections. ORDER_EHFRAME, // The TLS sections come first in the data section. ORDER_TLS_DATA, ORDER_TLS_BSS, // Local RELRO (read-only after relocation) sections come before // non-local RELRO sections. This data will be fully resolved by // the prelinker. ORDER_RELRO_LOCAL, // Non-local RELRO sections are grouped together after local RELRO // sections. All RELRO sections must be adjacent so that they can // all be put into a PT_GNU_RELRO segment. ORDER_RELRO, // We permit marking exactly one output section as the last RELRO // section. We do this so that the read-only GOT can be adjacent to // the writable GOT. ORDER_RELRO_LAST, // Similarly, we permit marking exactly one output section as the // first non-RELRO section. ORDER_NON_RELRO_FIRST, // The regular data sections come after the RELRO sections. ORDER_DATA, // Large data sections normally go in large data segments. ORDER_LARGE_DATA, // Group writable notes so that we can have a single PT_NOTE // segment. ORDER_RW_NOTE, // The small data sections must be at the end of the data sections, // so that they can be adjacent to the small BSS sections. ORDER_SMALL_DATA, // The BSS sections start here. // The small BSS sections must be at the start of the BSS sections, // so that they can be adjacent to the small data sections. ORDER_SMALL_BSS, // The regular BSS sections. ORDER_BSS, // The large BSS sections come after the other BSS sections. ORDER_LARGE_BSS, // Maximum value. ORDER_MAX }; // This class handles the details of laying out input sections. class Layout { public: Layout(int number_of_input_files, Script_options*); ~Layout() { delete this->relaxation_debug_check_; delete this->segment_states_; } // For incremental links, record the base file to be modified. void set_incremental_base(Incremental_binary* base); Incremental_binary* incremental_base() { return this->incremental_base_; } // For incremental links, record the initial fixed layout of a section // from the base file, and return a pointer to the Output_section. template Output_section* init_fixed_output_section(const char*, elfcpp::Shdr&); // Given an input section SHNDX, named NAME, with data in SHDR, from // the object file OBJECT, return the output section where this // input section should go. RELOC_SHNDX is the index of a // relocation section which applies to this section, or 0 if none, // or -1U if more than one. RELOC_TYPE is the type of the // relocation section if there is one. Set *OFFSET to the offset // within the output section. template Output_section* layout(Sized_relobj_file *object, unsigned int shndx, const char* name, const elfcpp::Shdr& shdr, unsigned int reloc_shndx, unsigned int reloc_type, off_t* offset); std::map* get_section_order_map() { return &this->section_order_map_; } // Struct to store segment info when mapping some input sections to // unique segments using linker plugins. Mapping an input section to // a unique segment is done by first placing such input sections in // unique output sections and then mapping the output section to a // unique segment. NAME is the name of the output section. FLAGS // and ALIGN are the extra flags and alignment of the segment. struct Unique_segment_info { // Identifier for the segment. ELF segments dont have names. This // is used as the name of the output section mapped to the segment. const char* name; // Additional segment flags. uint64_t flags; // Segment alignment. uint64_t align; }; // Mapping from input section to segment. typedef std::map Section_segment_map; // Maps section SECN to SEGMENT s. void insert_section_segment_map(Const_section_id secn, Unique_segment_info *s); // Some input sections require special ordering, for compatibility // with GNU ld. Given the name of an input section, return -1 if it // does not require special ordering. Otherwise, return the index // by which it should be ordered compared to other input sections // that require special ordering. static int special_ordering_of_input_section(const char* name); bool is_section_ordering_specified() { return this->section_ordering_specified_; } void set_section_ordering_specified() { this->section_ordering_specified_ = true; } bool is_unique_segment_for_sections_specified() const { return this->unique_segment_for_sections_specified_; } void set_unique_segment_for_sections_specified() { this->unique_segment_for_sections_specified_ = true; } // For incremental updates, allocate a block of memory from the // free list. Find a block starting at or after MINOFF. off_t allocate(off_t len, uint64_t align, off_t minoff) { return this->free_list_.allocate(len, align, minoff); } unsigned int find_section_order_index(const std::string&); // Read the sequence of input sections from the file specified with // linker option --section-ordering-file. void read_layout_from_file(); // Layout an input reloc section when doing a relocatable link. The // section is RELOC_SHNDX in OBJECT, with data in SHDR. // DATA_SECTION is the reloc section to which it refers. RR is the // relocatable information. template Output_section* layout_reloc(Sized_relobj_file* object, unsigned int reloc_shndx, const elfcpp::Shdr& shdr, Output_section* data_section, Relocatable_relocs* rr); // Layout a group section when doing a relocatable link. template void layout_group(Symbol_table* symtab, Sized_relobj_file* object, unsigned int group_shndx, const char* group_section_name, const char* signature, const elfcpp::Shdr& shdr, elfcpp::Elf_Word flags, std::vector* shndxes); // Like layout, only for exception frame sections. OBJECT is an // object file. SYMBOLS is the contents of the symbol table // section, with size SYMBOLS_SIZE. SYMBOL_NAMES is the contents of // the symbol name section, with size SYMBOL_NAMES_SIZE. SHNDX is a // .eh_frame section in OBJECT. SHDR is the section header. // RELOC_SHNDX is the index of a relocation section which applies to // this section, or 0 if none, or -1U if more than one. RELOC_TYPE // is the type of the relocation section if there is one. This // returns the output section, and sets *OFFSET to the offset. template Output_section* layout_eh_frame(Sized_relobj_file* object, const unsigned char* symbols, off_t symbols_size, const unsigned char* symbol_names, off_t symbol_names_size, unsigned int shndx, const elfcpp::Shdr& shdr, unsigned int reloc_shndx, unsigned int reloc_type, off_t* offset); // After processing all input files, we call this to make sure that // the optimized .eh_frame sections have been added to the output // section. void finalize_eh_frame_section(); // Add .eh_frame information for a PLT. The FDE must start with a // 4-byte PC-relative reference to the start of the PLT, followed by // a 4-byte size of PLT. void add_eh_frame_for_plt(Output_data* plt, const unsigned char* cie_data, size_t cie_length, const unsigned char* fde_data, size_t fde_length); // Scan a .debug_info or .debug_types section, and add summary // information to the .gdb_index section. template void add_to_gdb_index(bool is_type_unit, Sized_relobj* object, const unsigned char* symbols, off_t symbols_size, unsigned int shndx, unsigned int reloc_shndx, unsigned int reloc_type); // Handle a GNU stack note. This is called once per input object // file. SEEN_GNU_STACK is true if the object file has a // .note.GNU-stack section. GNU_STACK_FLAGS is the section flags // from that section if there was one. void layout_gnu_stack(bool seen_gnu_stack, uint64_t gnu_stack_flags, const Object*); // Add an Output_section_data to the layout. This is used for // special sections like the GOT section. ORDER is where the // section should wind up in the output segment. IS_RELRO is true // for relro sections. Output_section* add_output_section_data(const char* name, elfcpp::Elf_Word type, elfcpp::Elf_Xword flags, Output_section_data*, Output_section_order order, bool is_relro); // Increase the size of the relro segment by this much. void increase_relro(unsigned int s) { this->increase_relro_ += s; } // Create dynamic sections if necessary. void create_initial_dynamic_sections(Symbol_table*); // Define __start and __stop symbols for output sections. void define_section_symbols(Symbol_table*); // Create automatic note sections. void create_notes(); // Create sections for linker scripts. void create_script_sections() { this->script_options_->create_script_sections(this); } // Define symbols from any linker script. void define_script_symbols(Symbol_table* symtab) { this->script_options_->add_symbols_to_table(symtab); } // Define symbols for group signatures. void define_group_signatures(Symbol_table*); // Return the Stringpool used for symbol names. const Stringpool* sympool() const { return &this->sympool_; } // Return the Stringpool used for dynamic symbol names and dynamic // tags. const Stringpool* dynpool() const { return &this->dynpool_; } // Return the .dynamic output section. This is only valid after the // layout has been finalized. Output_section* dynamic_section() const { return this->dynamic_section_; } // Return the symtab_xindex section used to hold large section // indexes for the normal symbol table. Output_symtab_xindex* symtab_xindex() const { return this->symtab_xindex_; } // Return the dynsym_xindex section used to hold large section // indexes for the dynamic symbol table. Output_symtab_xindex* dynsym_xindex() const { return this->dynsym_xindex_; } // Return whether a section is a .gnu.linkonce section, given the // section name. static inline bool is_linkonce(const char* name) { return strncmp(name, ".gnu.linkonce", sizeof(".gnu.linkonce") - 1) == 0; } // Whether we have added an input section. bool have_added_input_section() const { return this->have_added_input_section_; } // Return true if a section is a debugging section. static inline bool is_debug_info_section(const char* name) { // Debugging sections can only be recognized by name. return (strncmp(name, ".debug", sizeof(".debug") - 1) == 0 || strncmp(name, ".zdebug", sizeof(".zdebug") - 1) == 0 || strncmp(name, ".gnu.linkonce.wi.", sizeof(".gnu.linkonce.wi.") - 1) == 0 || strncmp(name, ".line", sizeof(".line") - 1) == 0 || strncmp(name, ".stab", sizeof(".stab") - 1) == 0); } // Return true if RELOBJ is an input file whose base name matches // FILE_NAME. The base name must have an extension of ".o", and // must be exactly FILE_NAME.o or FILE_NAME, one character, ".o". static bool match_file_name(const Relobj* relobj, const char* file_name); // Return whether section SHNDX in RELOBJ is a .ctors/.dtors section // with more than one word being mapped to a .init_array/.fini_array // section. bool is_ctors_in_init_array(Relobj* relobj, unsigned int shndx) const; // Check if a comdat group or .gnu.linkonce section with the given // NAME is selected for the link. If there is already a section, // *KEPT_SECTION is set to point to the signature and the function // returns false. Otherwise, OBJECT, SHNDX,IS_COMDAT, and // IS_GROUP_NAME are recorded for this NAME in the layout object, // *KEPT_SECTION is set to the internal copy and the function return // false. bool find_or_add_kept_section(const std::string& name, Relobj* object, unsigned int shndx, bool is_comdat, bool is_group_name, Kept_section** kept_section); // Finalize the layout after all the input sections have been added. off_t finalize(const Input_objects*, Symbol_table*, Target*, const Task*); // Return whether any sections require postprocessing. bool any_postprocessing_sections() const { return this->any_postprocessing_sections_; } // Return the size of the output file. off_t output_file_size() const { return this->output_file_size_; } // Return the TLS segment. This will return NULL if there isn't // one. Output_segment* tls_segment() const { return this->tls_segment_; } // Return the normal symbol table. Output_section* symtab_section() const { gold_assert(this->symtab_section_ != NULL); return this->symtab_section_; } // Return the file offset of the normal symbol table. off_t symtab_section_offset() const; // Return the section index of the normal symbol tabl.e unsigned int symtab_section_shndx() const; // Return the dynamic symbol table. Output_section* dynsym_section() const { gold_assert(this->dynsym_section_ != NULL); return this->dynsym_section_; } // Return the dynamic tags. Output_data_dynamic* dynamic_data() const { return this->dynamic_data_; } // Write out the output sections. void write_output_sections(Output_file* of) const; // Write out data not associated with an input file or the symbol // table. void write_data(const Symbol_table*, Output_file*) const; // Write out output sections which can not be written until all the // input sections are complete. void write_sections_after_input_sections(Output_file* of); // Return an output section named NAME, or NULL if there is none. Output_section* find_output_section(const char* name) const; // Return an output segment of type TYPE, with segment flags SET set // and segment flags CLEAR clear. Return NULL if there is none. Output_segment* find_output_segment(elfcpp::PT type, elfcpp::Elf_Word set, elfcpp::Elf_Word clear) const; // Return the number of segments we expect to produce. size_t expected_segment_count() const; // Set a flag to indicate that an object file uses the static TLS model. void set_has_static_tls() { this->has_static_tls_ = true; } // Return true if any object file uses the static TLS model. bool has_static_tls() const { return this->has_static_tls_; } // Return the options which may be set by a linker script. Script_options* script_options() { return this->script_options_; } const Script_options* script_options() const { return this->script_options_; } // Return the object managing inputs in incremental build. NULL in // non-incremental builds. Incremental_inputs* incremental_inputs() const { return this->incremental_inputs_; } // For the target-specific code to add dynamic tags which are common // to most targets. void add_target_dynamic_tags(bool use_rel, const Output_data* plt_got, const Output_data* plt_rel, const Output_data_reloc_generic* dyn_rel, bool add_debug, bool dynrel_includes_plt); // If a treehash is necessary to compute the build ID, then queue // the necessary tasks and return a blocker that will unblock when // they finish. Otherwise return BUILD_ID_BLOCKER. Task_token* queue_build_id_tasks(Workqueue* workqueue, Task_token* build_id_blocker, Output_file* of); // Compute and write out the build ID if needed. void write_build_id(Output_file*) const; // Rewrite output file in binary format. void write_binary(Output_file* in) const; // Print output sections to the map file. void print_to_mapfile(Mapfile*) const; // Dump statistical information to stderr. void print_stats() const; // A list of segments. typedef std::vector Segment_list; // A list of sections. typedef std::vector Section_list; // The list of information to write out which is not attached to // either a section or a segment. typedef std::vector Data_list; // Store the allocated sections into the section list. This is used // by the linker script code. void get_allocated_sections(Section_list*) const; // Store the executable sections into the section list. void get_executable_sections(Section_list*) const; // Make a section for a linker script to hold data. Output_section* make_output_section_for_script(const char* name, Script_sections::Section_type section_type); // Make a segment. This is used by the linker script code. Output_segment* make_output_segment(elfcpp::Elf_Word type, elfcpp::Elf_Word flags); // Return the number of segments. size_t segment_count() const { return this->segment_list_.size(); } // Map from section flags to segment flags. static elfcpp::Elf_Word section_flags_to_segment(elfcpp::Elf_Xword flags); // Attach sections to segments. void attach_sections_to_segments(const Target*); // For relaxation clean up, we need to know output section data created // from a linker script. void new_output_section_data_from_script(Output_section_data* posd) { if (this->record_output_section_data_from_script_) this->script_output_section_data_list_.push_back(posd); } // Return section list. const Section_list& section_list() const { return this->section_list_; } // Returns TRUE iff NAME (an input section from RELOBJ) will // be mapped to an output section that should be KEPT. bool keep_input_section(const Relobj*, const char*); // Add a special output object that will be recreated afresh // if there is another relaxation iteration. void add_relax_output(Output_data* data) { this->relax_output_list_.push_back(data); } // Clear out (and free) everything added by add_relax_output. void reset_relax_output(); private: Layout(const Layout&); Layout& operator=(const Layout&); // Mapping from input section names to output section names. struct Section_name_mapping { const char* from; int fromlen; const char* to; int tolen; }; static const Section_name_mapping section_name_mapping[]; static const int section_name_mapping_count; // During a relocatable link, a list of group sections and // signatures. struct Group_signature { // The group section. Output_section* section; // The signature. const char* signature; Group_signature() : section(NULL), signature(NULL) { } Group_signature(Output_section* sectiona, const char* signaturea) : section(sectiona), signature(signaturea) { } }; typedef std::vector Group_signatures; // Create a note section, filling in the header. Output_section* create_note(const char* name, int note_type, const char* section_name, size_t descsz, bool allocate, size_t* trailing_padding); // Create a note section for gold version. void create_gold_note(); // Record whether the stack must be executable. void create_executable_stack_info(); // Create a build ID note if needed. void create_build_id(); // Link .stab and .stabstr sections. void link_stabs_sections(); // Create .gnu_incremental_inputs and .gnu_incremental_strtab sections needed // for the next run of incremental linking to check what has changed. void create_incremental_info_sections(Symbol_table*); // Find the first read-only PT_LOAD segment, creating one if // necessary. Output_segment* find_first_load_seg(const Target*); // Count the local symbols in the regular symbol table and the dynamic // symbol table, and build the respective string pools. void count_local_symbols(const Task*, const Input_objects*); // Create the output sections for the symbol table. void create_symtab_sections(const Input_objects*, Symbol_table*, unsigned int, off_t*); // Create the .shstrtab section. Output_section* create_shstrtab(); // Create the section header table. void create_shdrs(const Output_section* shstrtab_section, off_t*); // Create the dynamic symbol table. void create_dynamic_symtab(const Input_objects*, Symbol_table*, Output_section** pdynstr, unsigned int* plocal_dynamic_count, std::vector* pdynamic_symbols, Versions* versions); // Assign offsets to each local portion of the dynamic symbol table. void assign_local_dynsym_offsets(const Input_objects*); // Finish the .dynamic section and PT_DYNAMIC segment. void finish_dynamic_section(const Input_objects*, const Symbol_table*); // Set the size of the _DYNAMIC symbol. void set_dynamic_symbol_size(const Symbol_table*); // Create the .interp section and PT_INTERP segment. void create_interp(const Target* target); // Create the version sections. void create_version_sections(const Versions*, const Symbol_table*, unsigned int local_symcount, const std::vector& dynamic_symbols, const Output_section* dynstr); template void sized_create_version_sections(const Versions* versions, const Symbol_table*, unsigned int local_symcount, const std::vector& dynamic_symbols, const Output_section* dynstr); // Return whether to include this section in the link. template bool include_section(Sized_relobj_file* object, const char* name, const elfcpp::Shdr&); // Return the output section name to use given an input section // name. Set *PLEN to the length of the name. *PLEN must be // initialized to the length of NAME. static const char* output_section_name(const Relobj*, const char* name, size_t* plen); // Return the number of allocated output sections. size_t allocated_output_section_count() const; // Return the output section for NAME, TYPE and FLAGS. Output_section* get_output_section(const char* name, Stringpool::Key name_key, elfcpp::Elf_Word type, elfcpp::Elf_Xword flags, Output_section_order order, bool is_relro); // Clear the input section flags that should not be copied to the // output section. elfcpp::Elf_Xword get_output_section_flags (elfcpp::Elf_Xword input_section_flags); // Choose the output section for NAME in RELOBJ. Output_section* choose_output_section(const Relobj* relobj, const char* name, elfcpp::Elf_Word type, elfcpp::Elf_Xword flags, bool is_input_section, Output_section_order order, bool is_relro); // Create a new Output_section. Output_section* make_output_section(const char* name, elfcpp::Elf_Word type, elfcpp::Elf_Xword flags, Output_section_order order, bool is_relro); // Attach a section to a segment. void attach_section_to_segment(const Target*, Output_section*); // Get section order. Output_section_order default_section_order(Output_section*, bool is_relro_local); // Attach an allocated section to a segment. void attach_allocated_section_to_segment(const Target*, Output_section*); // Make the .eh_frame section. Output_section* make_eh_frame_section(const Relobj*); // Set the final file offsets of all the segments. off_t set_segment_offsets(const Target*, Output_segment*, unsigned int* pshndx); // Set the file offsets of the sections when doing a relocatable // link. off_t set_relocatable_section_offsets(Output_data*, unsigned int* pshndx); // Set the final file offsets of all the sections not associated // with a segment. We set section offsets in three passes: the // first handles all allocated sections, the second sections that // require postprocessing, and the last the late-bound STRTAB // sections (probably only shstrtab, which is the one we care about // because it holds section names). enum Section_offset_pass { BEFORE_INPUT_SECTIONS_PASS, POSTPROCESSING_SECTIONS_PASS, STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS }; off_t set_section_offsets(off_t, Section_offset_pass pass); // Set the final section indexes of all the sections not associated // with a segment. Returns the next unused index. unsigned int set_section_indexes(unsigned int pshndx); // Set the section addresses when using a script. Output_segment* set_section_addresses_from_script(Symbol_table*); // Find appropriate places or orphan sections in a script. void place_orphan_sections_in_script(); // Return whether SEG1 comes before SEG2 in the output file. bool segment_precedes(const Output_segment* seg1, const Output_segment* seg2); // Use to save and restore segments during relaxation. typedef Unordered_map Segment_states; // Save states of current output segments. void save_segments(Segment_states*); // Restore output segment states. void restore_segments(const Segment_states*); // Clean up after relaxation so that it is possible to lay out the // sections and segments again. void clean_up_after_relaxation(); // Doing preparation work for relaxation. This is factored out to make // Layout::finalized a bit smaller and easier to read. void prepare_for_relaxation(); // Main body of the relaxation loop, which lays out the section. off_t relaxation_loop_body(int, Target*, Symbol_table*, Output_segment**, Output_segment*, Output_segment_headers*, Output_file_header*, unsigned int*); // A mapping used for kept comdats/.gnu.linkonce group signatures. typedef Unordered_map Signatures; // Mapping from input section name/type/flags to output section. We // use canonicalized strings here. typedef std::pair > Key; struct Hash_key { size_t operator()(const Key& k) const; }; typedef Unordered_map Section_name_map; // A comparison class for segments. class Compare_segments { public: Compare_segments(Layout* layout) : layout_(layout) { } bool operator()(const Output_segment* seg1, const Output_segment* seg2) { return this->layout_->segment_precedes(seg1, seg2); } private: Layout* layout_; }; typedef std::vector Output_section_data_list; // Debug checker class. class Relaxation_debug_check { public: Relaxation_debug_check() : section_infos_() { } // Check that sections and special data are in reset states. void check_output_data_for_reset_values(const Layout::Section_list&, const Layout::Data_list& special_outputs, const Layout::Data_list& relax_outputs); // Record information of a section list. void read_sections(const Layout::Section_list&); // Verify a section list with recorded information. void verify_sections(const Layout::Section_list&); private: // Information we care about a section. struct Section_info { // Output section described by this. Output_section* output_section; // Load address. uint64_t address; // Data size. off_t data_size; // File offset. off_t offset; }; // Section information. std::vector section_infos_; }; // The number of input files, for sizing tables. int number_of_input_files_; // Information set by scripts or by command line options. Script_options* script_options_; // The output section names. Stringpool namepool_; // The output symbol names. Stringpool sympool_; // The dynamic strings, if needed. Stringpool dynpool_; // The list of group sections and linkonce sections which we have seen. Signatures signatures_; // The mapping from input section name/type/flags to output sections. Section_name_map section_name_map_; // The list of output segments. Segment_list segment_list_; // The list of output sections. Section_list section_list_; // The list of output sections which are not attached to any output // segment. Section_list unattached_section_list_; // The list of unattached Output_data objects which require special // handling because they are not Output_sections. Data_list special_output_list_; // Like special_output_list_, but cleared and recreated on each // iteration of relaxation. Data_list relax_output_list_; // The section headers. Output_section_headers* section_headers_; // A pointer to the PT_TLS segment if there is one. Output_segment* tls_segment_; // A pointer to the PT_GNU_RELRO segment if there is one. Output_segment* relro_segment_; // A pointer to the PT_INTERP segment if there is one. Output_segment* interp_segment_; // A backend may increase the size of the PT_GNU_RELRO segment if // there is one. This is the amount to increase it by. unsigned int increase_relro_; // The SHT_SYMTAB output section. Output_section* symtab_section_; // The SHT_SYMTAB_SHNDX for the regular symbol table if there is one. Output_symtab_xindex* symtab_xindex_; // The SHT_DYNSYM output section if there is one. Output_section* dynsym_section_; // The SHT_SYMTAB_SHNDX for the dynamic symbol table if there is one. Output_symtab_xindex* dynsym_xindex_; // The SHT_DYNAMIC output section if there is one. Output_section* dynamic_section_; // The _DYNAMIC symbol if there is one. Symbol* dynamic_symbol_; // The dynamic data which goes into dynamic_section_. Output_data_dynamic* dynamic_data_; // The exception frame output section if there is one. Output_section* eh_frame_section_; // The exception frame data for eh_frame_section_. Eh_frame* eh_frame_data_; // Whether we have added eh_frame_data_ to the .eh_frame section. bool added_eh_frame_data_; // The exception frame header output section if there is one. Output_section* eh_frame_hdr_section_; // The data for the .gdb_index section. Gdb_index* gdb_index_data_; // The space for the build ID checksum if there is one. Output_section_data* build_id_note_; // Temporary storage for tree hash of build ID. unsigned char* array_of_hashes_; // Size of array_of_hashes_ (in bytes). size_t size_of_array_of_hashes_; // Input view for computing tree hash of build ID. Freed in write_build_id(). const unsigned char* input_view_; // The output section containing dwarf abbreviations Output_reduced_debug_abbrev_section* debug_abbrev_; // The output section containing the dwarf debug info tree Output_reduced_debug_info_section* debug_info_; // A list of group sections and their signatures. Group_signatures group_signatures_; // The size of the output file. off_t output_file_size_; // Whether we have added an input section to an output section. bool have_added_input_section_; // Whether we have attached the sections to the segments. bool sections_are_attached_; // Whether we have seen an object file marked to require an // executable stack. bool input_requires_executable_stack_; // Whether we have seen at least one object file with an executable // stack marker. bool input_with_gnu_stack_note_; // Whether we have seen at least one object file without an // executable stack marker. bool input_without_gnu_stack_note_; // Whether we have seen an object file that uses the static TLS model. bool has_static_tls_; // Whether any sections require postprocessing. bool any_postprocessing_sections_; // Whether we have resized the signatures_ hash table. bool resized_signatures_; // Whether we have created a .stab*str output section. bool have_stabstr_section_; // True if the input sections in the output sections should be sorted // as specified in a section ordering file. bool section_ordering_specified_; // True if some input sections need to be mapped to a unique segment, // after being mapped to a unique Output_section. bool unique_segment_for_sections_specified_; // In incremental build, holds information check the inputs and build the // .gnu_incremental_inputs section. Incremental_inputs* incremental_inputs_; // Whether we record output section data created in script bool record_output_section_data_from_script_; // List of output data that needs to be removed at relaxation clean up. Output_section_data_list script_output_section_data_list_; // Structure to save segment states before entering the relaxation loop. Segment_states* segment_states_; // A relaxation debug checker. We only create one when in debugging mode. Relaxation_debug_check* relaxation_debug_check_; // Plugins specify section_ordering using this map. This is set in // update_section_order in plugin.cc std::map section_order_map_; // This maps an input section to a unique segment. This is done by first // placing such input sections in unique output sections and then mapping // the output section to a unique segment. Unique_segment_info stores // any additional flags and alignment of the new segment. Section_segment_map section_segment_map_; // Hash a pattern to its position in the section ordering file. Unordered_map input_section_position_; // Vector of glob only patterns in the section_ordering file. std::vector input_section_glob_; // For incremental links, the base file to be modified. Incremental_binary* incremental_base_; // For incremental links, a list of free space within the file. Free_list free_list_; }; // This task handles writing out data in output sections which is not // part of an input section, or which requires special handling. When // this is done, it unblocks both output_sections_blocker and // final_blocker. class Write_sections_task : public Task { public: Write_sections_task(const Layout* layout, Output_file* of, Task_token* output_sections_blocker, Task_token* input_sections_blocker, Task_token* final_blocker) : layout_(layout), of_(of), output_sections_blocker_(output_sections_blocker), input_sections_blocker_(input_sections_blocker), final_blocker_(final_blocker) { } // The standard Task methods. Task_token* is_runnable(); void locks(Task_locker*); void run(Workqueue*); std::string get_name() const { return "Write_sections_task"; } private: class Write_sections_locker; const Layout* layout_; Output_file* of_; Task_token* output_sections_blocker_; Task_token* input_sections_blocker_; Task_token* final_blocker_; }; // This task handles writing out data which is not part of a section // or segment. class Write_data_task : public Task { public: Write_data_task(const Layout* layout, const Symbol_table* symtab, Output_file* of, Task_token* final_blocker) : layout_(layout), symtab_(symtab), of_(of), final_blocker_(final_blocker) { } // The standard Task methods. Task_token* is_runnable(); void locks(Task_locker*); void run(Workqueue*); std::string get_name() const { return "Write_data_task"; } private: const Layout* layout_; const Symbol_table* symtab_; Output_file* of_; Task_token* final_blocker_; }; // This task handles writing out the global symbols. class Write_symbols_task : public Task { public: Write_symbols_task(const Layout* layout, const Symbol_table* symtab, const Input_objects* /*input_objects*/, const Stringpool* sympool, const Stringpool* dynpool, Output_file* of, Task_token* final_blocker) : layout_(layout), symtab_(symtab), sympool_(sympool), dynpool_(dynpool), of_(of), final_blocker_(final_blocker) { } // The standard Task methods. Task_token* is_runnable(); void locks(Task_locker*); void run(Workqueue*); std::string get_name() const { return "Write_symbols_task"; } private: const Layout* layout_; const Symbol_table* symtab_; const Stringpool* sympool_; const Stringpool* dynpool_; Output_file* of_; Task_token* final_blocker_; }; // This task handles writing out data in output sections which can't // be written out until all the input sections have been handled. // This is for sections whose contents is based on the contents of // other output sections. class Write_after_input_sections_task : public Task { public: Write_after_input_sections_task(Layout* layout, Output_file* of, Task_token* input_sections_blocker, Task_token* final_blocker) : layout_(layout), of_(of), input_sections_blocker_(input_sections_blocker), final_blocker_(final_blocker) { } // The standard Task methods. Task_token* is_runnable(); void locks(Task_locker*); void run(Workqueue*); std::string get_name() const { return "Write_after_input_sections_task"; } private: Layout* layout_; Output_file* of_; Task_token* input_sections_blocker_; Task_token* final_blocker_; }; // This task function handles closing the file. class Close_task_runner : public Task_function_runner { public: Close_task_runner(const General_options* options, const Layout* layout, Output_file* of) : options_(options), layout_(layout), of_(of) { } // Run the operation. void run(Workqueue*, const Task*); private: const General_options* options_; const Layout* layout_; Output_file* of_; }; // A small helper function to align an address. inline uint64_t align_address(uint64_t address, uint64_t addralign) { if (addralign != 0) address = (address + addralign - 1) &~ (addralign - 1); return address; } } // End namespace gold. #endif // !defined(GOLD_LAYOUT_H)