// target.h -- target support for gold -*- C++ -*- // Copyright (C) 2006-2021 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. // The abstract class Target is the interface for target specific // support. It defines abstract methods which each target must // implement. Typically there will be one target per processor, but // in some cases it may be necessary to have subclasses. // For speed and consistency we want to use inline functions to handle // relocation processing. So besides implementations of the abstract // methods, each target is expected to define a template // specialization of the relocation functions. #ifndef GOLD_TARGET_H #define GOLD_TARGET_H #include "elfcpp.h" #include "options.h" #include "parameters.h" #include "stringpool.h" #include "debug.h" namespace gold { class Object; class Relobj; template class Sized_relobj; template class Sized_relobj_file; class Relocatable_relocs; template struct Relocate_info; class Reloc_symbol_changes; class Symbol; template class Sized_symbol; class Symbol_table; class Output_data; class Output_data_got_base; class Output_section; class Input_objects; class Task; struct Symbol_location; class Versions; // The abstract class for target specific handling. class Target { public: virtual ~Target() { } // Return the bit size that this target implements. This should // return 32 or 64. int get_size() const { return this->pti_->size; } // Return whether this target is big-endian. bool is_big_endian() const { return this->pti_->is_big_endian; } // Machine code to store in e_machine field of ELF header. elfcpp::EM machine_code() const { return this->pti_->machine_code; } // Processor specific flags to store in e_flags field of ELF header. elfcpp::Elf_Word processor_specific_flags() const { return this->processor_specific_flags_; } // Whether processor specific flags are set at least once. bool are_processor_specific_flags_set() const { return this->are_processor_specific_flags_set_; } // Whether this target has a specific make_symbol function. bool has_make_symbol() const { return this->pti_->has_make_symbol; } // Whether this target has a specific resolve function. bool has_resolve() const { return this->pti_->has_resolve; } // Whether this target has a specific code fill function. bool has_code_fill() const { return this->pti_->has_code_fill; } // Return the default name of the dynamic linker. const char* dynamic_linker() const { return this->pti_->dynamic_linker; } // Return the default address to use for the text segment. // If a -z max-page-size argument has set the ABI page size // to a value larger than the default starting address, // bump the starting address up to the page size, to avoid // misaligning the text segment in the file. uint64_t default_text_segment_address() const { uint64_t addr = this->pti_->default_text_segment_address; uint64_t pagesize = this->abi_pagesize(); if (addr < pagesize) addr = pagesize; return addr; } // Return the ABI specified page size. uint64_t abi_pagesize() const { if (parameters->options().max_page_size() > 0) return parameters->options().max_page_size(); else return this->pti_->abi_pagesize; } // Return the common page size used on actual systems. uint64_t common_pagesize() const { if (parameters->options().common_page_size() > 0) return std::min(parameters->options().common_page_size(), this->abi_pagesize()); else return std::min(this->pti_->common_pagesize, this->abi_pagesize()); } // Return whether PF_X segments must contain nothing but the contents of // SHF_EXECINSTR sections (no non-executable data, no headers). bool isolate_execinstr() const { return this->pti_->isolate_execinstr; } uint64_t rosegment_gap() const { return this->pti_->rosegment_gap; } // If we see some object files with .note.GNU-stack sections, and // some objects files without them, this returns whether we should // consider the object files without them to imply that the stack // should be executable. bool is_default_stack_executable() const { return this->pti_->is_default_stack_executable; } // Return a character which may appear as a prefix for a wrap // symbol. If this character appears, we strip it when checking for // wrapping and add it back when forming the final symbol name. // This should be '\0' if not special prefix is required, which is // the normal case. char wrap_char() const { return this->pti_->wrap_char; } // Return the special section index which indicates a small common // symbol. This will return SHN_UNDEF if there are no small common // symbols. elfcpp::Elf_Half small_common_shndx() const { return this->pti_->small_common_shndx; } // Return values to add to the section flags for the section holding // small common symbols. elfcpp::Elf_Xword small_common_section_flags() const { gold_assert(this->pti_->small_common_shndx != elfcpp::SHN_UNDEF); return this->pti_->small_common_section_flags; } // Return the special section index which indicates a large common // symbol. This will return SHN_UNDEF if there are no large common // symbols. elfcpp::Elf_Half large_common_shndx() const { return this->pti_->large_common_shndx; } // Return values to add to the section flags for the section holding // large common symbols. elfcpp::Elf_Xword large_common_section_flags() const { gold_assert(this->pti_->large_common_shndx != elfcpp::SHN_UNDEF); return this->pti_->large_common_section_flags; } // This hook is called when an output section is created. void new_output_section(Output_section* os) const { this->do_new_output_section(os); } // This is called to tell the target to complete any sections it is // handling. After this all sections must have their final size. void finalize_sections(Layout* layout, const Input_objects* input_objects, Symbol_table* symtab) { return this->do_finalize_sections(layout, input_objects, symtab); } // Return the value to use for a global symbol which needs a special // value in the dynamic symbol table. This will only be called if // the backend first calls symbol->set_needs_dynsym_value(). uint64_t dynsym_value(const Symbol* sym) const { return this->do_dynsym_value(sym); } // Return a string to use to fill out a code section. This is // basically one or more NOPS which must fill out the specified // length in bytes. std::string code_fill(section_size_type length) const { return this->do_code_fill(length); } // Return whether SYM is known to be defined by the ABI. This is // used to avoid inappropriate warnings about undefined symbols. bool is_defined_by_abi(const Symbol* sym) const { return this->do_is_defined_by_abi(sym); } // Adjust the output file header before it is written out. VIEW // points to the header in external form. LEN is the length. void adjust_elf_header(unsigned char* view, int len) { return this->do_adjust_elf_header(view, len); } // Return address and size to plug into eh_frame FDEs associated with a PLT. void plt_fde_location(const Output_data* plt, unsigned char* oview, uint64_t* address, off_t* len) const { return this->do_plt_fde_location(plt, oview, address, len); } // Return whether NAME is a local label name. This is used to implement the // --discard-locals options. bool is_local_label_name(const char* name) const { return this->do_is_local_label_name(name); } // Get the symbol index to use for a target specific reloc. unsigned int reloc_symbol_index(void* arg, unsigned int type) const { return this->do_reloc_symbol_index(arg, type); } // Get the addend to use for a target specific reloc. uint64_t reloc_addend(void* arg, unsigned int type, uint64_t addend) const { return this->do_reloc_addend(arg, type, addend); } // Return the PLT address to use for a global symbol. uint64_t plt_address_for_global(const Symbol* sym) const { return this->do_plt_address_for_global(sym); } // Return the PLT address to use for a local symbol. uint64_t plt_address_for_local(const Relobj* object, unsigned int symndx) const { return this->do_plt_address_for_local(object, symndx); } // Return the offset to use for the GOT_INDX'th got entry which is // for a local tls symbol specified by OBJECT, SYMNDX. int64_t tls_offset_for_local(const Relobj* object, unsigned int symndx, Output_data_got_base* got, unsigned int got_indx, uint64_t addend) const { return do_tls_offset_for_local(object, symndx, got, got_indx, addend); } // Return the offset to use for the GOT_INDX'th got entry which is // for global tls symbol GSYM. int64_t tls_offset_for_global(Symbol* gsym, Output_data_got_base* got, unsigned int got_indx, uint64_t addend) const { return do_tls_offset_for_global(gsym, got, got_indx, addend); } // For targets that use function descriptors, if LOC is the location // of a function, modify it to point at the function entry location. void function_location(Symbol_location* loc) const { return do_function_location(loc); } // Return whether this target can use relocation types to determine // if a function's address is taken. bool can_check_for_function_pointers() const { return this->do_can_check_for_function_pointers(); } // Return whether a relocation to a merged section can be processed // to retrieve the contents. bool can_icf_inline_merge_sections () const { return this->pti_->can_icf_inline_merge_sections; } // Whether a section called SECTION_NAME may have function pointers to // sections not eligible for safe ICF folding. virtual bool section_may_have_icf_unsafe_pointers(const char* section_name) const { return this->do_section_may_have_icf_unsafe_pointers(section_name); } // Return the base to use for the PC value in an FDE when it is // encoded using DW_EH_PE_datarel. This does not appear to be // documented anywhere, but it is target specific. Any use of // DW_EH_PE_datarel in gcc requires defining a special macro // (ASM_MAYBE_OUTPUT_ENCODED_ADDR_RTX) to output the value. uint64_t ehframe_datarel_base() const { return this->do_ehframe_datarel_base(); } // Return true if a reference to SYM from a reloc at *PRELOC // means that the current function may call an object compiled // without -fsplit-stack. SYM is known to be defined in an object // compiled without -fsplit-stack. bool is_call_to_non_split(const Symbol* sym, const unsigned char* preloc, const unsigned char* view, section_size_type view_size) const { return this->do_is_call_to_non_split(sym, preloc, view, view_size); } // A function starts at OFFSET in section SHNDX in OBJECT. That // function was compiled with -fsplit-stack, but it refers to a // function which was compiled without -fsplit-stack. VIEW is a // modifiable view of the section; VIEW_SIZE is the size of the // view. The target has to adjust the function so that it allocates // enough stack. void calls_non_split(Relobj* object, unsigned int shndx, section_offset_type fnoffset, section_size_type fnsize, const unsigned char* prelocs, size_t reloc_count, unsigned char* view, section_size_type view_size, std::string* from, std::string* to) const { this->do_calls_non_split(object, shndx, fnoffset, fnsize, prelocs, reloc_count, view, view_size, from, to); } // Make an ELF object. template Object* make_elf_object(const std::string& name, Input_file* input_file, off_t offset, const elfcpp::Ehdr& ehdr) { return this->do_make_elf_object(name, input_file, offset, ehdr); } // Make an output section. Output_section* make_output_section(const char* name, elfcpp::Elf_Word type, elfcpp::Elf_Xword flags) { return this->do_make_output_section(name, type, flags); } // Return true if target wants to perform relaxation. bool may_relax() const { // Run the dummy relaxation pass twice if relaxation debugging is enabled. if (is_debugging_enabled(DEBUG_RELAXATION)) return true; return this->do_may_relax(); } // Perform a relaxation pass. Return true if layout may be changed. bool relax(int pass, const Input_objects* input_objects, Symbol_table* symtab, Layout* layout, const Task* task) { // Run the dummy relaxation pass twice if relaxation debugging is enabled. if (is_debugging_enabled(DEBUG_RELAXATION)) return pass < 2; return this->do_relax(pass, input_objects, symtab, layout, task); } // Return the target-specific name of attributes section. This is // NULL if a target does not use attributes section or if it uses // the default section name ".gnu.attributes". const char* attributes_section() const { return this->pti_->attributes_section; } // Return the vendor name of vendor attributes. const char* attributes_vendor() const { return this->pti_->attributes_vendor; } // Whether a section called NAME is an attribute section. bool is_attributes_section(const char* name) const { return ((this->pti_->attributes_section != NULL && strcmp(name, this->pti_->attributes_section) == 0) || strcmp(name, ".gnu.attributes") == 0); } // Return a bit mask of argument types for attribute with TAG. int attribute_arg_type(int tag) const { return this->do_attribute_arg_type(tag); } // Return the attribute tag of the position NUM in the list of fixed // attributes. Normally there is no reordering and // attributes_order(NUM) == NUM. int attributes_order(int num) const { return this->do_attributes_order(num); } // When a target is selected as the default target, we call this method, // which may be used for expensive, target-specific initialization. void select_as_default_target() { this->do_select_as_default_target(); } // Return the value to store in the EI_OSABI field in the ELF // header. elfcpp::ELFOSABI osabi() const { return this->osabi_; } // Set the value to store in the EI_OSABI field in the ELF header. void set_osabi(elfcpp::ELFOSABI osabi) { this->osabi_ = osabi; } // Define target-specific standard symbols. void define_standard_symbols(Symbol_table* symtab, Layout* layout) { this->do_define_standard_symbols(symtab, layout); } // Return the output section name to use given an input section // name, or NULL if no target specific name mapping is required. // Set *PLEN to the length of the name if returning non-NULL. const char* output_section_name(const Relobj* relobj, const char* name, size_t* plen) const { return this->do_output_section_name(relobj, name, plen); } // Add any special sections for this symbol to the gc work list. void gc_mark_symbol(Symbol_table* symtab, Symbol* sym) const { this->do_gc_mark_symbol(symtab, sym); } // Return the name of the entry point symbol. const char* entry_symbol_name() const { return this->pti_->entry_symbol_name; } // Return the size in bits of SHT_HASH entry. int hash_entry_size() const { return this->pti_->hash_entry_size; } // Return the section type to use for unwind sections. unsigned int unwind_section_type() const { return this->pti_->unwind_section_type; } // Whether the target has a custom set_dynsym_indexes method. bool has_custom_set_dynsym_indexes() const { return this->do_has_custom_set_dynsym_indexes(); } // Custom set_dynsym_indexes method for a target. unsigned int set_dynsym_indexes(std::vector* dyn_symbols, unsigned int index, std::vector* syms, Stringpool* dynpool, Versions* versions, Symbol_table* symtab) const { return this->do_set_dynsym_indexes(dyn_symbols, index, syms, dynpool, versions, symtab); } // Get the custom dynamic tag value. unsigned int dynamic_tag_custom_value(elfcpp::DT tag) const { return this->do_dynamic_tag_custom_value(tag); } // Adjust the value written to the dynamic symbol table. void adjust_dyn_symbol(const Symbol* sym, unsigned char* view) const { this->do_adjust_dyn_symbol(sym, view); } // Return whether to include the section in the link. bool should_include_section(elfcpp::Elf_Word sh_type) const { return this->do_should_include_section(sh_type); } // Finalize the target-specific properties in the .note.gnu.property section. void finalize_gnu_properties(Layout* layout) const { this->do_finalize_gnu_properties(layout); } protected: // This struct holds the constant information for a child class. We // use a struct to avoid the overhead of virtual function calls for // simple information. struct Target_info { // Address size (32 or 64). int size; // Whether the target is big endian. bool is_big_endian; // The code to store in the e_machine field of the ELF header. elfcpp::EM machine_code; // Whether this target has a specific make_symbol function. bool has_make_symbol; // Whether this target has a specific resolve function. bool has_resolve; // Whether this target has a specific code fill function. bool has_code_fill; // Whether an object file with no .note.GNU-stack sections implies // that the stack should be executable. bool is_default_stack_executable; // Whether a relocation to a merged section can be processed to // retrieve the contents. bool can_icf_inline_merge_sections; // Prefix character to strip when checking for wrapping. char wrap_char; // The default dynamic linker name. const char* dynamic_linker; // The default text segment address. uint64_t default_text_segment_address; // The ABI specified page size. uint64_t abi_pagesize; // The common page size used by actual implementations. uint64_t common_pagesize; // Whether PF_X segments must contain nothing but the contents of // SHF_EXECINSTR sections (no non-executable data, no headers). bool isolate_execinstr; // If nonzero, distance from the text segment to the read-only segment. uint64_t rosegment_gap; // The special section index for small common symbols; SHN_UNDEF // if none. elfcpp::Elf_Half small_common_shndx; // The special section index for large common symbols; SHN_UNDEF // if none. elfcpp::Elf_Half large_common_shndx; // Section flags for small common section. elfcpp::Elf_Xword small_common_section_flags; // Section flags for large common section. elfcpp::Elf_Xword large_common_section_flags; // Name of attributes section if it is not ".gnu.attributes". const char* attributes_section; // Vendor name of vendor attributes. const char* attributes_vendor; // Name of the main entry point to the program. const char* entry_symbol_name; // Size (in bits) of SHT_HASH entry. Always equal to 32, except for // 64-bit S/390. const int hash_entry_size; // Processor-specific section type for ".eh_frame" (unwind) sections. // SHT_PROGBITS if there is no special section type. const unsigned int unwind_section_type; }; Target(const Target_info* pti) : pti_(pti), processor_specific_flags_(0), are_processor_specific_flags_set_(false), osabi_(elfcpp::ELFOSABI_NONE) { } // Virtual function which may be implemented by the child class. virtual void do_new_output_section(Output_section*) const { } // Virtual function which may be implemented by the child class. virtual void do_finalize_sections(Layout*, const Input_objects*, Symbol_table*) { } // Virtual function which may be implemented by the child class. virtual uint64_t do_dynsym_value(const Symbol*) const { gold_unreachable(); } // Virtual function which must be implemented by the child class if // needed. virtual std::string do_code_fill(section_size_type) const { gold_unreachable(); } // Virtual function which may be implemented by the child class. virtual bool do_is_defined_by_abi(const Symbol*) const { return false; } // Adjust the output file header before it is written out. VIEW // points to the header in external form. LEN is the length, and // will be one of the values of elfcpp::Elf_sizes::ehdr_size. // By default, we set the EI_OSABI field if requested (in // Sized_target). virtual void do_adjust_elf_header(unsigned char*, int) = 0; // Return address and size to plug into eh_frame FDEs associated with a PLT. virtual void do_plt_fde_location(const Output_data* plt, unsigned char* oview, uint64_t* address, off_t* len) const; // Virtual function which may be overridden by the child class. virtual bool do_is_local_label_name(const char*) const; // Virtual function that must be overridden by a target which uses // target specific relocations. virtual unsigned int do_reloc_symbol_index(void*, unsigned int) const { gold_unreachable(); } // Virtual function that must be overridden by a target which uses // target specific relocations. virtual uint64_t do_reloc_addend(void*, unsigned int, uint64_t) const { gold_unreachable(); } // Virtual functions that must be overridden by a target that uses // STT_GNU_IFUNC symbols. virtual uint64_t do_plt_address_for_global(const Symbol*) const { gold_unreachable(); } virtual uint64_t do_plt_address_for_local(const Relobj*, unsigned int) const { gold_unreachable(); } virtual int64_t do_tls_offset_for_local(const Relobj*, unsigned int, Output_data_got_base*, unsigned int, uint64_t) const { gold_unreachable(); } virtual int64_t do_tls_offset_for_global(Symbol*, Output_data_got_base*, unsigned int, uint64_t) const { gold_unreachable(); } virtual void do_function_location(Symbol_location*) const = 0; // Virtual function which may be overriden by the child class. virtual bool do_can_check_for_function_pointers() const { return false; } // Virtual function which may be overridden by the child class. We // recognize some default sections for which we don't care whether // they have function pointers. virtual bool do_section_may_have_icf_unsafe_pointers(const char* section_name) const { // We recognize sections for normal vtables, construction vtables and // EH frames. return (!is_prefix_of(".rodata._ZTV", section_name) && !is_prefix_of(".data.rel.ro._ZTV", section_name) && !is_prefix_of(".rodata._ZTC", section_name) && !is_prefix_of(".data.rel.ro._ZTC", section_name) && !is_prefix_of(".eh_frame", section_name)); } virtual uint64_t do_ehframe_datarel_base() const { gold_unreachable(); } // Virtual function which may be overridden by the child class. The // default implementation is that any function not defined by the // ABI is a call to a non-split function. virtual bool do_is_call_to_non_split(const Symbol* sym, const unsigned char*, const unsigned char*, section_size_type) const; // Virtual function which may be overridden by the child class. virtual void do_calls_non_split(Relobj* object, unsigned int, section_offset_type, section_size_type, const unsigned char*, size_t, unsigned char*, section_size_type, std::string*, std::string*) const; // make_elf_object hooks. There are four versions of these for // different address sizes and endianness. // Set processor specific flags. void set_processor_specific_flags(elfcpp::Elf_Word flags) { this->processor_specific_flags_ = flags; this->are_processor_specific_flags_set_ = true; } #ifdef HAVE_TARGET_32_LITTLE // Virtual functions which may be overridden by the child class. virtual Object* do_make_elf_object(const std::string&, Input_file*, off_t, const elfcpp::Ehdr<32, false>&); #endif #ifdef HAVE_TARGET_32_BIG // Virtual functions which may be overridden by the child class. virtual Object* do_make_elf_object(const std::string&, Input_file*, off_t, const elfcpp::Ehdr<32, true>&); #endif #ifdef HAVE_TARGET_64_LITTLE // Virtual functions which may be overridden by the child class. virtual Object* do_make_elf_object(const std::string&, Input_file*, off_t, const elfcpp::Ehdr<64, false>& ehdr); #endif #ifdef HAVE_TARGET_64_BIG // Virtual functions which may be overridden by the child class. virtual Object* do_make_elf_object(const std::string& name, Input_file* input_file, off_t offset, const elfcpp::Ehdr<64, true>& ehdr); #endif // Virtual functions which may be overridden by the child class. virtual Output_section* do_make_output_section(const char* name, elfcpp::Elf_Word type, elfcpp::Elf_Xword flags); // Virtual function which may be overridden by the child class. virtual bool do_may_relax() const { return parameters->options().relax(); } // Virtual function which may be overridden by the child class. virtual bool do_relax(int, const Input_objects*, Symbol_table*, Layout*, const Task*) { return false; } // A function for targets to call. Return whether BYTES/LEN matches // VIEW/VIEW_SIZE at OFFSET. bool match_view(const unsigned char* view, section_size_type view_size, section_offset_type offset, const char* bytes, size_t len) const; // Set the contents of a VIEW/VIEW_SIZE to nops starting at OFFSET // for LEN bytes. void set_view_to_nop(unsigned char* view, section_size_type view_size, section_offset_type offset, size_t len) const; // This must be overridden by the child class if it has target-specific // attributes subsection in the attribute section. virtual int do_attribute_arg_type(int) const { gold_unreachable(); } // This may be overridden by the child class. virtual int do_attributes_order(int num) const { return num; } // This may be overridden by the child class. virtual void do_select_as_default_target() { } // This may be overridden by the child class. virtual void do_define_standard_symbols(Symbol_table*, Layout*) { } // This may be overridden by the child class. virtual const char* do_output_section_name(const Relobj*, const char*, size_t*) const { return NULL; } // This may be overridden by the child class. virtual void do_gc_mark_symbol(Symbol_table*, Symbol*) const { } // This may be overridden by the child class. virtual bool do_has_custom_set_dynsym_indexes() const { return false; } // This may be overridden by the child class. virtual unsigned int do_set_dynsym_indexes(std::vector*, unsigned int, std::vector*, Stringpool*, Versions*, Symbol_table*) const { gold_unreachable(); } // This may be overridden by the child class. virtual unsigned int do_dynamic_tag_custom_value(elfcpp::DT) const { gold_unreachable(); } // This may be overridden by the child class. virtual void do_adjust_dyn_symbol(const Symbol*, unsigned char*) const { } // This may be overridden by the child class. virtual bool do_should_include_section(elfcpp::Elf_Word) const { return true; } // Finalize the target-specific properties in the .note.gnu.property section. virtual void do_finalize_gnu_properties(Layout*) const { } private: // The implementations of the four do_make_elf_object virtual functions are // almost identical except for their sizes and endianness. We use a template. // for their implementations. template inline Object* do_make_elf_object_implementation(const std::string&, Input_file*, off_t, const elfcpp::Ehdr&); Target(const Target&); Target& operator=(const Target&); // The target information. const Target_info* pti_; // Processor-specific flags. elfcpp::Elf_Word processor_specific_flags_; // Whether the processor-specific flags are set at least once. bool are_processor_specific_flags_set_; // If not ELFOSABI_NONE, the value to put in the EI_OSABI field of // the ELF header. This is handled at this level because it is // OS-specific rather than processor-specific. elfcpp::ELFOSABI osabi_; }; // The abstract class for a specific size and endianness of target. // Each actual target implementation class should derive from an // instantiation of Sized_target. template class Sized_target : public Target { public: // Make a new symbol table entry for the target. This should be // overridden by a target which needs additional information in the // symbol table. This will only be called if has_make_symbol() // returns true. virtual Sized_symbol* make_symbol(const char*, elfcpp::STT, Object*, unsigned int, uint64_t) { gold_unreachable(); } // Resolve a symbol for the target. This should be overridden by a // target which needs to take special action. TO is the // pre-existing symbol. SYM is the new symbol, seen in OBJECT. // VERSION is the version of SYM. This will only be called if // has_resolve() returns true. virtual bool resolve(Symbol*, const elfcpp::Sym&, Object*, const char*) { gold_unreachable(); } // Process the relocs for a section, and record information of the // mapping from source to destination sections. This mapping is later // used to determine unreferenced garbage sections. This procedure is // only called during garbage collection. virtual void gc_process_relocs(Symbol_table* symtab, Layout* layout, Sized_relobj_file* object, unsigned int data_shndx, unsigned int sh_type, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, bool needs_special_offset_handling, size_t local_symbol_count, const unsigned char* plocal_symbols) = 0; // Scan the relocs for a section, and record any information // required for the symbol. SYMTAB is the symbol table. OBJECT is // the object in which the section appears. DATA_SHNDX is the // section index that these relocs apply to. SH_TYPE is the type of // the relocation section, SHT_REL or SHT_RELA. PRELOCS points to // the relocation data. RELOC_COUNT is the number of relocs. // LOCAL_SYMBOL_COUNT is the number of local symbols. // OUTPUT_SECTION is the output section. // NEEDS_SPECIAL_OFFSET_HANDLING is true if offsets to the output // sections are not mapped as usual. PLOCAL_SYMBOLS points to the // local symbol data from OBJECT. GLOBAL_SYMBOLS is the array of // pointers to the global symbol table from OBJECT. virtual void scan_relocs(Symbol_table* symtab, Layout* layout, Sized_relobj_file* object, unsigned int data_shndx, unsigned int sh_type, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, bool needs_special_offset_handling, size_t local_symbol_count, const unsigned char* plocal_symbols) = 0; // Relocate section data. SH_TYPE is the type of the relocation // section, SHT_REL or SHT_RELA. PRELOCS points to the relocation // information. RELOC_COUNT is the number of relocs. // OUTPUT_SECTION is the output section. // NEEDS_SPECIAL_OFFSET_HANDLING is true if offsets must be mapped // to correspond to the output section. VIEW is a view into the // output file holding the section contents, VIEW_ADDRESS is the // virtual address of the view, and VIEW_SIZE is the size of the // view. If NEEDS_SPECIAL_OFFSET_HANDLING is true, the VIEW_xx // parameters refer to the complete output section data, not just // the input section data. virtual void relocate_section(const Relocate_info*, unsigned int sh_type, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, bool needs_special_offset_handling, unsigned char* view, typename elfcpp::Elf_types::Elf_Addr view_address, section_size_type view_size, const Reloc_symbol_changes*) = 0; // Scan the relocs during a relocatable link. The parameters are // like scan_relocs, with an additional Relocatable_relocs // parameter, used to record the disposition of the relocs. virtual void scan_relocatable_relocs(Symbol_table* symtab, Layout* layout, Sized_relobj_file* object, unsigned int data_shndx, unsigned int sh_type, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, bool needs_special_offset_handling, size_t local_symbol_count, const unsigned char* plocal_symbols, Relocatable_relocs*) = 0; // Scan the relocs for --emit-relocs. The parameters are // like scan_relocatable_relocs. virtual void emit_relocs_scan(Symbol_table* symtab, Layout* layout, Sized_relobj_file* object, unsigned int data_shndx, unsigned int sh_type, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, bool needs_special_offset_handling, size_t local_symbol_count, const unsigned char* plocal_syms, Relocatable_relocs* rr) = 0; // Emit relocations for a section during a relocatable link, and for // --emit-relocs. The parameters are like relocate_section, with // additional parameters for the view of the output reloc section. virtual void relocate_relocs(const Relocate_info*, unsigned int sh_type, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, typename elfcpp::Elf_types::Elf_Off offset_in_output_section, unsigned char* view, typename elfcpp::Elf_types::Elf_Addr view_address, section_size_type view_size, unsigned char* reloc_view, section_size_type reloc_view_size) = 0; // Perform target-specific processing in a relocatable link. This is // only used if we use the relocation strategy RELOC_SPECIAL. // RELINFO points to a Relocation_info structure. SH_TYPE is the relocation // section type. PRELOC_IN points to the original relocation. RELNUM is // the index number of the relocation in the relocation section. // OUTPUT_SECTION is the output section to which the relocation is applied. // OFFSET_IN_OUTPUT_SECTION is the offset of the relocation input section // within the output section. VIEW points to the output view of the // output section. VIEW_ADDRESS is output address of the view. VIEW_SIZE // is the size of the output view and PRELOC_OUT points to the new // relocation in the output object. // // A target only needs to override this if the generic code in // target-reloc.h cannot handle some relocation types. virtual void relocate_special_relocatable(const Relocate_info* /*relinfo */, unsigned int /* sh_type */, const unsigned char* /* preloc_in */, size_t /* relnum */, Output_section* /* output_section */, typename elfcpp::Elf_types::Elf_Off /* offset_in_output_section */, unsigned char* /* view */, typename elfcpp::Elf_types::Elf_Addr /* view_address */, section_size_type /* view_size */, unsigned char* /* preloc_out*/) { gold_unreachable(); } // Return the number of entries in the GOT. This is only used for // laying out the incremental link info sections. A target needs // to implement this to support incremental linking. virtual unsigned int got_entry_count() const { gold_unreachable(); } // Return the number of entries in the PLT. This is only used for // laying out the incremental link info sections. A target needs // to implement this to support incremental linking. virtual unsigned int plt_entry_count() const { gold_unreachable(); } // Return the offset of the first non-reserved PLT entry. This is // only used for laying out the incremental link info sections. // A target needs to implement this to support incremental linking. virtual unsigned int first_plt_entry_offset() const { gold_unreachable(); } // Return the size of each PLT entry. This is only used for // laying out the incremental link info sections. A target needs // to implement this to support incremental linking. virtual unsigned int plt_entry_size() const { gold_unreachable(); } // Return the size of each GOT entry. This is only used for // laying out the incremental link info sections. A target needs // to implement this if its GOT size is different. virtual unsigned int got_entry_size() const { return size / 8; } // Create the GOT and PLT sections for an incremental update. // A target needs to implement this to support incremental linking. virtual Output_data_got_base* init_got_plt_for_update(Symbol_table*, Layout*, unsigned int /* got_count */, unsigned int /* plt_count */) { gold_unreachable(); } // Reserve a GOT entry for a local symbol, and regenerate any // necessary dynamic relocations. virtual void reserve_local_got_entry(unsigned int /* got_index */, Sized_relobj* /* obj */, unsigned int /* r_sym */, unsigned int /* got_type */) { gold_unreachable(); } // Reserve a GOT entry for a global symbol, and regenerate any // necessary dynamic relocations. virtual void reserve_global_got_entry(unsigned int /* got_index */, Symbol* /* gsym */, unsigned int /* got_type */) { gold_unreachable(); } // Register an existing PLT entry for a global symbol. // A target needs to implement this to support incremental linking. virtual void register_global_plt_entry(Symbol_table*, Layout*, unsigned int /* plt_index */, Symbol*) { gold_unreachable(); } // Force a COPY relocation for a given symbol. // A target needs to implement this to support incremental linking. virtual void emit_copy_reloc(Symbol_table*, Symbol*, Output_section*, off_t) { gold_unreachable(); } // Apply an incremental relocation. virtual void apply_relocation(const Relocate_info* /* relinfo */, typename elfcpp::Elf_types::Elf_Addr /* r_offset */, unsigned int /* r_type */, typename elfcpp::Elf_types::Elf_Swxword /* r_addend */, const Symbol* /* gsym */, unsigned char* /* view */, typename elfcpp::Elf_types::Elf_Addr /* address */, section_size_type /* view_size */) { gold_unreachable(); } // Handle target specific gc actions when adding a gc reference from // SRC_OBJ, SRC_SHNDX to a location specified by DST_OBJ, DST_SHNDX // and DST_OFF. void gc_add_reference(Symbol_table* symtab, Relobj* src_obj, unsigned int src_shndx, Relobj* dst_obj, unsigned int dst_shndx, typename elfcpp::Elf_types::Elf_Addr dst_off) const { this->do_gc_add_reference(symtab, src_obj, src_shndx, dst_obj, dst_shndx, dst_off); } // Return the r_sym field from a relocation. // Most targets can use the default version of this routine, // but some targets have a non-standard r_info field, and will // need to provide a target-specific version. virtual unsigned int get_r_sym(const unsigned char* preloc) const { // Since REL and RELA relocs share the same structure through // the r_info field, we can just use REL here. elfcpp::Rel rel(preloc); return elfcpp::elf_r_sym(rel.get_r_info()); } // Record a target-specific program property in the .note.gnu.property // section. virtual void record_gnu_property(unsigned int, unsigned int, size_t, const unsigned char*, const Object*) { } // Merge the target-specific program properties from the current object. virtual void merge_gnu_properties(const Object*) { } protected: Sized_target(const Target::Target_info* pti) : Target(pti) { gold_assert(pti->size == size); gold_assert(pti->is_big_endian ? big_endian : !big_endian); } // Set the EI_OSABI field if requested. virtual void do_adjust_elf_header(unsigned char*, int); // Handle target specific gc actions when adding a gc reference. virtual void do_gc_add_reference(Symbol_table*, Relobj*, unsigned int, Relobj*, unsigned int, typename elfcpp::Elf_types::Elf_Addr) const { } virtual void do_function_location(Symbol_location*) const { } }; } // End namespace gold. #endif // !defined(GOLD_TARGET_H)