1 // target.h -- target support for gold -*- C++ -*-
3 // Copyright (C) 2006-2018 Free Software Foundation, Inc.
4 // Written by Ian Lance Taylor <iant@google.com>.
6 // This file is part of gold.
8 // This program is free software; you can redistribute it and/or modify
9 // it under the terms of the GNU General Public License as published by
10 // the Free Software Foundation; either version 3 of the License, or
11 // (at your option) any later version.
13 // This program is distributed in the hope that it will be useful,
14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 // GNU General Public License for more details.
18 // You should have received a copy of the GNU General Public License
19 // along with this program; if not, write to the Free Software
20 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
21 // MA 02110-1301, USA.
23 // The abstract class Target is the interface for target specific
24 // support. It defines abstract methods which each target must
25 // implement. Typically there will be one target per processor, but
26 // in some cases it may be necessary to have subclasses.
28 // For speed and consistency we want to use inline functions to handle
29 // relocation processing. So besides implementations of the abstract
30 // methods, each target is expected to define a template
31 // specialization of the relocation functions.
38 #include "parameters.h"
39 #include "stringpool.h"
47 template<int size, bool big_endian>
49 template<int size, bool big_endian>
50 class Sized_relobj_file;
51 class Relocatable_relocs;
52 template<int size, bool big_endian>
54 class Reloc_symbol_changes;
60 class Output_data_got_base;
64 struct Symbol_location;
67 // The abstract class for target specific handling.
75 // Return the bit size that this target implements. This should
79 { return this->pti_->size; }
81 // Return whether this target is big-endian.
84 { return this->pti_->is_big_endian; }
86 // Machine code to store in e_machine field of ELF header.
89 { return this->pti_->machine_code; }
91 // Processor specific flags to store in e_flags field of ELF header.
93 processor_specific_flags() const
94 { return this->processor_specific_flags_; }
96 // Whether processor specific flags are set at least once.
98 are_processor_specific_flags_set() const
99 { return this->are_processor_specific_flags_set_; }
101 // Whether this target has a specific make_symbol function.
103 has_make_symbol() const
104 { return this->pti_->has_make_symbol; }
106 // Whether this target has a specific resolve function.
109 { return this->pti_->has_resolve; }
111 // Whether this target has a specific code fill function.
113 has_code_fill() const
114 { return this->pti_->has_code_fill; }
116 // Return the default name of the dynamic linker.
118 dynamic_linker() const
119 { return this->pti_->dynamic_linker; }
121 // Return the default address to use for the text segment.
122 // If a -z max-page-size argument has set the ABI page size
123 // to a value larger than the default starting address,
124 // bump the starting address up to the page size, to avoid
125 // misaligning the text segment in the file.
127 default_text_segment_address() const
129 uint64_t addr = this->pti_->default_text_segment_address;
130 uint64_t pagesize = this->abi_pagesize();
136 // Return the ABI specified page size.
140 if (parameters->options().max_page_size() > 0)
141 return parameters->options().max_page_size();
143 return this->pti_->abi_pagesize;
146 // Return the common page size used on actual systems.
148 common_pagesize() const
150 if (parameters->options().common_page_size() > 0)
151 return std::min(parameters->options().common_page_size(),
152 this->abi_pagesize());
154 return std::min(this->pti_->common_pagesize,
155 this->abi_pagesize());
158 // Return whether PF_X segments must contain nothing but the contents of
159 // SHF_EXECINSTR sections (no non-executable data, no headers).
161 isolate_execinstr() const
162 { return this->pti_->isolate_execinstr; }
165 rosegment_gap() const
166 { return this->pti_->rosegment_gap; }
168 // If we see some object files with .note.GNU-stack sections, and
169 // some objects files without them, this returns whether we should
170 // consider the object files without them to imply that the stack
171 // should be executable.
173 is_default_stack_executable() const
174 { return this->pti_->is_default_stack_executable; }
176 // Return a character which may appear as a prefix for a wrap
177 // symbol. If this character appears, we strip it when checking for
178 // wrapping and add it back when forming the final symbol name.
179 // This should be '\0' if not special prefix is required, which is
183 { return this->pti_->wrap_char; }
185 // Return the special section index which indicates a small common
186 // symbol. This will return SHN_UNDEF if there are no small common
189 small_common_shndx() const
190 { return this->pti_->small_common_shndx; }
192 // Return values to add to the section flags for the section holding
193 // small common symbols.
195 small_common_section_flags() const
197 gold_assert(this->pti_->small_common_shndx != elfcpp::SHN_UNDEF);
198 return this->pti_->small_common_section_flags;
201 // Return the special section index which indicates a large common
202 // symbol. This will return SHN_UNDEF if there are no large common
205 large_common_shndx() const
206 { return this->pti_->large_common_shndx; }
208 // Return values to add to the section flags for the section holding
209 // large common symbols.
211 large_common_section_flags() const
213 gold_assert(this->pti_->large_common_shndx != elfcpp::SHN_UNDEF);
214 return this->pti_->large_common_section_flags;
217 // This hook is called when an output section is created.
219 new_output_section(Output_section* os) const
220 { this->do_new_output_section(os); }
222 // This is called to tell the target to complete any sections it is
223 // handling. After this all sections must have their final size.
225 finalize_sections(Layout* layout, const Input_objects* input_objects,
226 Symbol_table* symtab)
227 { return this->do_finalize_sections(layout, input_objects, symtab); }
229 // Return the value to use for a global symbol which needs a special
230 // value in the dynamic symbol table. This will only be called if
231 // the backend first calls symbol->set_needs_dynsym_value().
233 dynsym_value(const Symbol* sym) const
234 { return this->do_dynsym_value(sym); }
236 // Return a string to use to fill out a code section. This is
237 // basically one or more NOPS which must fill out the specified
240 code_fill(section_size_type length) const
241 { return this->do_code_fill(length); }
243 // Return whether SYM is known to be defined by the ABI. This is
244 // used to avoid inappropriate warnings about undefined symbols.
246 is_defined_by_abi(const Symbol* sym) const
247 { return this->do_is_defined_by_abi(sym); }
249 // Adjust the output file header before it is written out. VIEW
250 // points to the header in external form. LEN is the length.
252 adjust_elf_header(unsigned char* view, int len)
253 { return this->do_adjust_elf_header(view, len); }
255 // Return address and size to plug into eh_frame FDEs associated with a PLT.
257 plt_fde_location(const Output_data* plt, unsigned char* oview,
258 uint64_t* address, off_t* len) const
259 { return this->do_plt_fde_location(plt, oview, address, len); }
261 // Return whether NAME is a local label name. This is used to implement the
262 // --discard-locals options.
264 is_local_label_name(const char* name) const
265 { return this->do_is_local_label_name(name); }
267 // Get the symbol index to use for a target specific reloc.
269 reloc_symbol_index(void* arg, unsigned int type) const
270 { return this->do_reloc_symbol_index(arg, type); }
272 // Get the addend to use for a target specific reloc.
274 reloc_addend(void* arg, unsigned int type, uint64_t addend) const
275 { return this->do_reloc_addend(arg, type, addend); }
277 // Return the PLT address to use for a global symbol.
279 plt_address_for_global(const Symbol* sym) const
280 { return this->do_plt_address_for_global(sym); }
282 // Return the PLT address to use for a local symbol.
284 plt_address_for_local(const Relobj* object, unsigned int symndx) const
285 { return this->do_plt_address_for_local(object, symndx); }
287 // Return the offset to use for the GOT_INDX'th got entry which is
288 // for a local tls symbol specified by OBJECT, SYMNDX.
290 tls_offset_for_local(const Relobj* object,
292 unsigned int got_indx) const
293 { return do_tls_offset_for_local(object, symndx, got_indx); }
295 // Return the offset to use for the GOT_INDX'th got entry which is
296 // for global tls symbol GSYM.
298 tls_offset_for_global(Symbol* gsym, unsigned int got_indx) const
299 { return do_tls_offset_for_global(gsym, got_indx); }
301 // For targets that use function descriptors, if LOC is the location
302 // of a function, modify it to point at the function entry location.
304 function_location(Symbol_location* loc) const
305 { return do_function_location(loc); }
307 // Return whether this target can use relocation types to determine
308 // if a function's address is taken.
310 can_check_for_function_pointers() const
311 { return this->do_can_check_for_function_pointers(); }
313 // Return whether a relocation to a merged section can be processed
314 // to retrieve the contents.
316 can_icf_inline_merge_sections () const
317 { return this->pti_->can_icf_inline_merge_sections; }
319 // Whether a section called SECTION_NAME may have function pointers to
320 // sections not eligible for safe ICF folding.
322 section_may_have_icf_unsafe_pointers(const char* section_name) const
323 { return this->do_section_may_have_icf_unsafe_pointers(section_name); }
325 // Return the base to use for the PC value in an FDE when it is
326 // encoded using DW_EH_PE_datarel. This does not appear to be
327 // documented anywhere, but it is target specific. Any use of
328 // DW_EH_PE_datarel in gcc requires defining a special macro
329 // (ASM_MAYBE_OUTPUT_ENCODED_ADDR_RTX) to output the value.
331 ehframe_datarel_base() const
332 { return this->do_ehframe_datarel_base(); }
334 // Return true if a reference to SYM from a reloc at *PRELOC
335 // means that the current function may call an object compiled
336 // without -fsplit-stack. SYM is known to be defined in an object
337 // compiled without -fsplit-stack.
339 is_call_to_non_split(const Symbol* sym, const unsigned char* preloc,
340 const unsigned char* view,
341 section_size_type view_size) const
342 { return this->do_is_call_to_non_split(sym, preloc, view, view_size); }
344 // A function starts at OFFSET in section SHNDX in OBJECT. That
345 // function was compiled with -fsplit-stack, but it refers to a
346 // function which was compiled without -fsplit-stack. VIEW is a
347 // modifiable view of the section; VIEW_SIZE is the size of the
348 // view. The target has to adjust the function so that it allocates
351 calls_non_split(Relobj* object, unsigned int shndx,
352 section_offset_type fnoffset, section_size_type fnsize,
353 const unsigned char* prelocs, size_t reloc_count,
354 unsigned char* view, section_size_type view_size,
355 std::string* from, std::string* to) const
357 this->do_calls_non_split(object, shndx, fnoffset, fnsize,
358 prelocs, reloc_count, view, view_size,
362 // Make an ELF object.
363 template<int size, bool big_endian>
365 make_elf_object(const std::string& name, Input_file* input_file,
366 off_t offset, const elfcpp::Ehdr<size, big_endian>& ehdr)
367 { return this->do_make_elf_object(name, input_file, offset, ehdr); }
369 // Make an output section.
371 make_output_section(const char* name, elfcpp::Elf_Word type,
372 elfcpp::Elf_Xword flags)
373 { return this->do_make_output_section(name, type, flags); }
375 // Return true if target wants to perform relaxation.
379 // Run the dummy relaxation pass twice if relaxation debugging is enabled.
380 if (is_debugging_enabled(DEBUG_RELAXATION))
383 return this->do_may_relax();
386 // Perform a relaxation pass. Return true if layout may be changed.
388 relax(int pass, const Input_objects* input_objects, Symbol_table* symtab,
389 Layout* layout, const Task* task)
391 // Run the dummy relaxation pass twice if relaxation debugging is enabled.
392 if (is_debugging_enabled(DEBUG_RELAXATION))
395 return this->do_relax(pass, input_objects, symtab, layout, task);
398 // Return the target-specific name of attributes section. This is
399 // NULL if a target does not use attributes section or if it uses
400 // the default section name ".gnu.attributes".
402 attributes_section() const
403 { return this->pti_->attributes_section; }
405 // Return the vendor name of vendor attributes.
407 attributes_vendor() const
408 { return this->pti_->attributes_vendor; }
410 // Whether a section called NAME is an attribute section.
412 is_attributes_section(const char* name) const
414 return ((this->pti_->attributes_section != NULL
415 && strcmp(name, this->pti_->attributes_section) == 0)
416 || strcmp(name, ".gnu.attributes") == 0);
419 // Return a bit mask of argument types for attribute with TAG.
421 attribute_arg_type(int tag) const
422 { return this->do_attribute_arg_type(tag); }
424 // Return the attribute tag of the position NUM in the list of fixed
425 // attributes. Normally there is no reordering and
426 // attributes_order(NUM) == NUM.
428 attributes_order(int num) const
429 { return this->do_attributes_order(num); }
431 // When a target is selected as the default target, we call this method,
432 // which may be used for expensive, target-specific initialization.
434 select_as_default_target()
435 { this->do_select_as_default_target(); }
437 // Return the value to store in the EI_OSABI field in the ELF
441 { return this->osabi_; }
443 // Set the value to store in the EI_OSABI field in the ELF header.
445 set_osabi(elfcpp::ELFOSABI osabi)
446 { this->osabi_ = osabi; }
448 // Define target-specific standard symbols.
450 define_standard_symbols(Symbol_table* symtab, Layout* layout)
451 { this->do_define_standard_symbols(symtab, layout); }
453 // Return the output section name to use given an input section
454 // name, or NULL if no target specific name mapping is required.
455 // Set *PLEN to the length of the name if returning non-NULL.
457 output_section_name(const Relobj* relobj,
460 { return this->do_output_section_name(relobj, name, plen); }
462 // Add any special sections for this symbol to the gc work list.
464 gc_mark_symbol(Symbol_table* symtab, Symbol* sym) const
465 { this->do_gc_mark_symbol(symtab, sym); }
467 // Return the name of the entry point symbol.
469 entry_symbol_name() const
470 { return this->pti_->entry_symbol_name; }
472 // Return the size in bits of SHT_HASH entry.
474 hash_entry_size() const
475 { return this->pti_->hash_entry_size; }
477 // Return the section type to use for unwind sections.
479 unwind_section_type() const
480 { return this->pti_->unwind_section_type; }
482 // Whether the target has a custom set_dynsym_indexes method.
484 has_custom_set_dynsym_indexes() const
485 { return this->do_has_custom_set_dynsym_indexes(); }
487 // Custom set_dynsym_indexes method for a target.
489 set_dynsym_indexes(std::vector<Symbol*>* dyn_symbols, unsigned int index,
490 std::vector<Symbol*>* syms, Stringpool* dynpool,
491 Versions* versions, Symbol_table* symtab) const
493 return this->do_set_dynsym_indexes(dyn_symbols, index, syms, dynpool,
497 // Get the custom dynamic tag value.
499 dynamic_tag_custom_value(elfcpp::DT tag) const
500 { return this->do_dynamic_tag_custom_value(tag); }
502 // Adjust the value written to the dynamic symbol table.
504 adjust_dyn_symbol(const Symbol* sym, unsigned char* view) const
505 { this->do_adjust_dyn_symbol(sym, view); }
507 // Return whether to include the section in the link.
509 should_include_section(elfcpp::Elf_Word sh_type) const
510 { return this->do_should_include_section(sh_type); }
513 // This struct holds the constant information for a child class. We
514 // use a struct to avoid the overhead of virtual function calls for
515 // simple information.
518 // Address size (32 or 64).
520 // Whether the target is big endian.
522 // The code to store in the e_machine field of the ELF header.
523 elfcpp::EM machine_code;
524 // Whether this target has a specific make_symbol function.
525 bool has_make_symbol;
526 // Whether this target has a specific resolve function.
528 // Whether this target has a specific code fill function.
530 // Whether an object file with no .note.GNU-stack sections implies
531 // that the stack should be executable.
532 bool is_default_stack_executable;
533 // Whether a relocation to a merged section can be processed to
534 // retrieve the contents.
535 bool can_icf_inline_merge_sections;
536 // Prefix character to strip when checking for wrapping.
538 // The default dynamic linker name.
539 const char* dynamic_linker;
540 // The default text segment address.
541 uint64_t default_text_segment_address;
542 // The ABI specified page size.
543 uint64_t abi_pagesize;
544 // The common page size used by actual implementations.
545 uint64_t common_pagesize;
546 // Whether PF_X segments must contain nothing but the contents of
547 // SHF_EXECINSTR sections (no non-executable data, no headers).
548 bool isolate_execinstr;
549 // If nonzero, distance from the text segment to the read-only segment.
550 uint64_t rosegment_gap;
551 // The special section index for small common symbols; SHN_UNDEF
553 elfcpp::Elf_Half small_common_shndx;
554 // The special section index for large common symbols; SHN_UNDEF
556 elfcpp::Elf_Half large_common_shndx;
557 // Section flags for small common section.
558 elfcpp::Elf_Xword small_common_section_flags;
559 // Section flags for large common section.
560 elfcpp::Elf_Xword large_common_section_flags;
561 // Name of attributes section if it is not ".gnu.attributes".
562 const char* attributes_section;
563 // Vendor name of vendor attributes.
564 const char* attributes_vendor;
565 // Name of the main entry point to the program.
566 const char* entry_symbol_name;
567 // Size (in bits) of SHT_HASH entry. Always equal to 32, except for
569 const int hash_entry_size;
570 // Processor-specific section type for ".eh_frame" (unwind) sections.
571 // SHT_PROGBITS if there is no special section type.
572 const unsigned int unwind_section_type;
575 Target(const Target_info* pti)
576 : pti_(pti), processor_specific_flags_(0),
577 are_processor_specific_flags_set_(false), osabi_(elfcpp::ELFOSABI_NONE)
580 // Virtual function which may be implemented by the child class.
582 do_new_output_section(Output_section*) const
585 // Virtual function which may be implemented by the child class.
587 do_finalize_sections(Layout*, const Input_objects*, Symbol_table*)
590 // Virtual function which may be implemented by the child class.
592 do_dynsym_value(const Symbol*) const
593 { gold_unreachable(); }
595 // Virtual function which must be implemented by the child class if
598 do_code_fill(section_size_type) const
599 { gold_unreachable(); }
601 // Virtual function which may be implemented by the child class.
603 do_is_defined_by_abi(const Symbol*) const
606 // Adjust the output file header before it is written out. VIEW
607 // points to the header in external form. LEN is the length, and
608 // will be one of the values of elfcpp::Elf_sizes<size>::ehdr_size.
609 // By default, we set the EI_OSABI field if requested (in
612 do_adjust_elf_header(unsigned char*, int) = 0;
614 // Return address and size to plug into eh_frame FDEs associated with a PLT.
616 do_plt_fde_location(const Output_data* plt, unsigned char* oview,
617 uint64_t* address, off_t* len) const;
619 // Virtual function which may be overridden by the child class.
621 do_is_local_label_name(const char*) const;
623 // Virtual function that must be overridden by a target which uses
624 // target specific relocations.
626 do_reloc_symbol_index(void*, unsigned int) const
627 { gold_unreachable(); }
629 // Virtual function that must be overridden by a target which uses
630 // target specific relocations.
632 do_reloc_addend(void*, unsigned int, uint64_t) const
633 { gold_unreachable(); }
635 // Virtual functions that must be overridden by a target that uses
636 // STT_GNU_IFUNC symbols.
638 do_plt_address_for_global(const Symbol*) const
639 { gold_unreachable(); }
642 do_plt_address_for_local(const Relobj*, unsigned int) const
643 { gold_unreachable(); }
646 do_tls_offset_for_local(const Relobj*, unsigned int, unsigned int) const
647 { gold_unreachable(); }
650 do_tls_offset_for_global(Symbol*, unsigned int) const
651 { gold_unreachable(); }
654 do_function_location(Symbol_location*) const = 0;
656 // Virtual function which may be overriden by the child class.
658 do_can_check_for_function_pointers() const
661 // Virtual function which may be overridden by the child class. We
662 // recognize some default sections for which we don't care whether
663 // they have function pointers.
665 do_section_may_have_icf_unsafe_pointers(const char* section_name) const
667 // We recognize sections for normal vtables, construction vtables and
669 return (!is_prefix_of(".rodata._ZTV", section_name)
670 && !is_prefix_of(".data.rel.ro._ZTV", section_name)
671 && !is_prefix_of(".rodata._ZTC", section_name)
672 && !is_prefix_of(".data.rel.ro._ZTC", section_name)
673 && !is_prefix_of(".eh_frame", section_name));
677 do_ehframe_datarel_base() const
678 { gold_unreachable(); }
680 // Virtual function which may be overridden by the child class. The
681 // default implementation is that any function not defined by the
682 // ABI is a call to a non-split function.
684 do_is_call_to_non_split(const Symbol* sym, const unsigned char*,
685 const unsigned char*, section_size_type) const;
687 // Virtual function which may be overridden by the child class.
689 do_calls_non_split(Relobj* object, unsigned int, section_offset_type,
690 section_size_type, const unsigned char*, size_t,
691 unsigned char*, section_size_type,
692 std::string*, std::string*) const;
694 // make_elf_object hooks. There are four versions of these for
695 // different address sizes and endianness.
697 // Set processor specific flags.
699 set_processor_specific_flags(elfcpp::Elf_Word flags)
701 this->processor_specific_flags_ = flags;
702 this->are_processor_specific_flags_set_ = true;
705 #ifdef HAVE_TARGET_32_LITTLE
706 // Virtual functions which may be overridden by the child class.
708 do_make_elf_object(const std::string&, Input_file*, off_t,
709 const elfcpp::Ehdr<32, false>&);
712 #ifdef HAVE_TARGET_32_BIG
713 // Virtual functions which may be overridden by the child class.
715 do_make_elf_object(const std::string&, Input_file*, off_t,
716 const elfcpp::Ehdr<32, true>&);
719 #ifdef HAVE_TARGET_64_LITTLE
720 // Virtual functions which may be overridden by the child class.
722 do_make_elf_object(const std::string&, Input_file*, off_t,
723 const elfcpp::Ehdr<64, false>& ehdr);
726 #ifdef HAVE_TARGET_64_BIG
727 // Virtual functions which may be overridden by the child class.
729 do_make_elf_object(const std::string& name, Input_file* input_file,
730 off_t offset, const elfcpp::Ehdr<64, true>& ehdr);
733 // Virtual functions which may be overridden by the child class.
734 virtual Output_section*
735 do_make_output_section(const char* name, elfcpp::Elf_Word type,
736 elfcpp::Elf_Xword flags);
738 // Virtual function which may be overridden by the child class.
741 { return parameters->options().relax(); }
743 // Virtual function which may be overridden by the child class.
745 do_relax(int, const Input_objects*, Symbol_table*, Layout*, const Task*)
748 // A function for targets to call. Return whether BYTES/LEN matches
749 // VIEW/VIEW_SIZE at OFFSET.
751 match_view(const unsigned char* view, section_size_type view_size,
752 section_offset_type offset, const char* bytes, size_t len) const;
754 // Set the contents of a VIEW/VIEW_SIZE to nops starting at OFFSET
757 set_view_to_nop(unsigned char* view, section_size_type view_size,
758 section_offset_type offset, size_t len) const;
760 // This must be overridden by the child class if it has target-specific
761 // attributes subsection in the attribute section.
763 do_attribute_arg_type(int) const
764 { gold_unreachable(); }
766 // This may be overridden by the child class.
768 do_attributes_order(int num) const
771 // This may be overridden by the child class.
773 do_select_as_default_target()
776 // This may be overridden by the child class.
778 do_define_standard_symbols(Symbol_table*, Layout*)
781 // This may be overridden by the child class.
783 do_output_section_name(const Relobj*, const char*, size_t*) const
786 // This may be overridden by the child class.
788 do_gc_mark_symbol(Symbol_table*, Symbol*) const
791 // This may be overridden by the child class.
793 do_has_custom_set_dynsym_indexes() const
796 // This may be overridden by the child class.
798 do_set_dynsym_indexes(std::vector<Symbol*>*, unsigned int,
799 std::vector<Symbol*>*, Stringpool*, Versions*,
801 { gold_unreachable(); }
803 // This may be overridden by the child class.
805 do_dynamic_tag_custom_value(elfcpp::DT) const
806 { gold_unreachable(); }
808 // This may be overridden by the child class.
810 do_adjust_dyn_symbol(const Symbol*, unsigned char*) const
813 // This may be overridden by the child class.
815 do_should_include_section(elfcpp::Elf_Word) const
819 // The implementations of the four do_make_elf_object virtual functions are
820 // almost identical except for their sizes and endianness. We use a template.
821 // for their implementations.
822 template<int size, bool big_endian>
824 do_make_elf_object_implementation(const std::string&, Input_file*, off_t,
825 const elfcpp::Ehdr<size, big_endian>&);
827 Target(const Target&);
828 Target& operator=(const Target&);
830 // The target information.
831 const Target_info* pti_;
832 // Processor-specific flags.
833 elfcpp::Elf_Word processor_specific_flags_;
834 // Whether the processor-specific flags are set at least once.
835 bool are_processor_specific_flags_set_;
836 // If not ELFOSABI_NONE, the value to put in the EI_OSABI field of
837 // the ELF header. This is handled at this level because it is
838 // OS-specific rather than processor-specific.
839 elfcpp::ELFOSABI osabi_;
842 // The abstract class for a specific size and endianness of target.
843 // Each actual target implementation class should derive from an
844 // instantiation of Sized_target.
846 template<int size, bool big_endian>
847 class Sized_target : public Target
850 // Make a new symbol table entry for the target. This should be
851 // overridden by a target which needs additional information in the
852 // symbol table. This will only be called if has_make_symbol()
854 virtual Sized_symbol<size>*
855 make_symbol(const char*, elfcpp::STT, Object*, unsigned int, uint64_t)
856 { gold_unreachable(); }
858 // Resolve a symbol for the target. This should be overridden by a
859 // target which needs to take special action. TO is the
860 // pre-existing symbol. SYM is the new symbol, seen in OBJECT.
861 // VERSION is the version of SYM. This will only be called if
862 // has_resolve() returns true.
864 resolve(Symbol*, const elfcpp::Sym<size, big_endian>&, Object*,
866 { gold_unreachable(); }
868 // Process the relocs for a section, and record information of the
869 // mapping from source to destination sections. This mapping is later
870 // used to determine unreferenced garbage sections. This procedure is
871 // only called during garbage collection.
873 gc_process_relocs(Symbol_table* symtab,
875 Sized_relobj_file<size, big_endian>* object,
876 unsigned int data_shndx,
877 unsigned int sh_type,
878 const unsigned char* prelocs,
880 Output_section* output_section,
881 bool needs_special_offset_handling,
882 size_t local_symbol_count,
883 const unsigned char* plocal_symbols) = 0;
885 // Scan the relocs for a section, and record any information
886 // required for the symbol. SYMTAB is the symbol table. OBJECT is
887 // the object in which the section appears. DATA_SHNDX is the
888 // section index that these relocs apply to. SH_TYPE is the type of
889 // the relocation section, SHT_REL or SHT_RELA. PRELOCS points to
890 // the relocation data. RELOC_COUNT is the number of relocs.
891 // LOCAL_SYMBOL_COUNT is the number of local symbols.
892 // OUTPUT_SECTION is the output section.
893 // NEEDS_SPECIAL_OFFSET_HANDLING is true if offsets to the output
894 // sections are not mapped as usual. PLOCAL_SYMBOLS points to the
895 // local symbol data from OBJECT. GLOBAL_SYMBOLS is the array of
896 // pointers to the global symbol table from OBJECT.
898 scan_relocs(Symbol_table* symtab,
900 Sized_relobj_file<size, big_endian>* object,
901 unsigned int data_shndx,
902 unsigned int sh_type,
903 const unsigned char* prelocs,
905 Output_section* output_section,
906 bool needs_special_offset_handling,
907 size_t local_symbol_count,
908 const unsigned char* plocal_symbols) = 0;
910 // Relocate section data. SH_TYPE is the type of the relocation
911 // section, SHT_REL or SHT_RELA. PRELOCS points to the relocation
912 // information. RELOC_COUNT is the number of relocs.
913 // OUTPUT_SECTION is the output section.
914 // NEEDS_SPECIAL_OFFSET_HANDLING is true if offsets must be mapped
915 // to correspond to the output section. VIEW is a view into the
916 // output file holding the section contents, VIEW_ADDRESS is the
917 // virtual address of the view, and VIEW_SIZE is the size of the
918 // view. If NEEDS_SPECIAL_OFFSET_HANDLING is true, the VIEW_xx
919 // parameters refer to the complete output section data, not just
920 // the input section data.
922 relocate_section(const Relocate_info<size, big_endian>*,
923 unsigned int sh_type,
924 const unsigned char* prelocs,
926 Output_section* output_section,
927 bool needs_special_offset_handling,
929 typename elfcpp::Elf_types<size>::Elf_Addr view_address,
930 section_size_type view_size,
931 const Reloc_symbol_changes*) = 0;
933 // Scan the relocs during a relocatable link. The parameters are
934 // like scan_relocs, with an additional Relocatable_relocs
935 // parameter, used to record the disposition of the relocs.
937 scan_relocatable_relocs(Symbol_table* symtab,
939 Sized_relobj_file<size, big_endian>* object,
940 unsigned int data_shndx,
941 unsigned int sh_type,
942 const unsigned char* prelocs,
944 Output_section* output_section,
945 bool needs_special_offset_handling,
946 size_t local_symbol_count,
947 const unsigned char* plocal_symbols,
948 Relocatable_relocs*) = 0;
950 // Scan the relocs for --emit-relocs. The parameters are
951 // like scan_relocatable_relocs.
953 emit_relocs_scan(Symbol_table* symtab,
955 Sized_relobj_file<size, big_endian>* object,
956 unsigned int data_shndx,
957 unsigned int sh_type,
958 const unsigned char* prelocs,
960 Output_section* output_section,
961 bool needs_special_offset_handling,
962 size_t local_symbol_count,
963 const unsigned char* plocal_syms,
964 Relocatable_relocs* rr) = 0;
966 // Emit relocations for a section during a relocatable link, and for
967 // --emit-relocs. The parameters are like relocate_section, with
968 // additional parameters for the view of the output reloc section.
970 relocate_relocs(const Relocate_info<size, big_endian>*,
971 unsigned int sh_type,
972 const unsigned char* prelocs,
974 Output_section* output_section,
975 typename elfcpp::Elf_types<size>::Elf_Off
976 offset_in_output_section,
978 typename elfcpp::Elf_types<size>::Elf_Addr view_address,
979 section_size_type view_size,
980 unsigned char* reloc_view,
981 section_size_type reloc_view_size) = 0;
983 // Perform target-specific processing in a relocatable link. This is
984 // only used if we use the relocation strategy RELOC_SPECIAL.
985 // RELINFO points to a Relocation_info structure. SH_TYPE is the relocation
986 // section type. PRELOC_IN points to the original relocation. RELNUM is
987 // the index number of the relocation in the relocation section.
988 // OUTPUT_SECTION is the output section to which the relocation is applied.
989 // OFFSET_IN_OUTPUT_SECTION is the offset of the relocation input section
990 // within the output section. VIEW points to the output view of the
991 // output section. VIEW_ADDRESS is output address of the view. VIEW_SIZE
992 // is the size of the output view and PRELOC_OUT points to the new
993 // relocation in the output object.
995 // A target only needs to override this if the generic code in
996 // target-reloc.h cannot handle some relocation types.
999 relocate_special_relocatable(const Relocate_info<size, big_endian>*
1001 unsigned int /* sh_type */,
1002 const unsigned char* /* preloc_in */,
1003 size_t /* relnum */,
1004 Output_section* /* output_section */,
1005 typename elfcpp::Elf_types<size>::Elf_Off
1006 /* offset_in_output_section */,
1007 unsigned char* /* view */,
1008 typename elfcpp::Elf_types<size>::Elf_Addr
1010 section_size_type /* view_size */,
1011 unsigned char* /* preloc_out*/)
1012 { gold_unreachable(); }
1014 // Return the number of entries in the GOT. This is only used for
1015 // laying out the incremental link info sections. A target needs
1016 // to implement this to support incremental linking.
1018 virtual unsigned int
1019 got_entry_count() const
1020 { gold_unreachable(); }
1022 // Return the number of entries in the PLT. This is only used for
1023 // laying out the incremental link info sections. A target needs
1024 // to implement this to support incremental linking.
1026 virtual unsigned int
1027 plt_entry_count() const
1028 { gold_unreachable(); }
1030 // Return the offset of the first non-reserved PLT entry. This is
1031 // only used for laying out the incremental link info sections.
1032 // A target needs to implement this to support incremental linking.
1034 virtual unsigned int
1035 first_plt_entry_offset() const
1036 { gold_unreachable(); }
1038 // Return the size of each PLT entry. This is only used for
1039 // laying out the incremental link info sections. A target needs
1040 // to implement this to support incremental linking.
1042 virtual unsigned int
1043 plt_entry_size() const
1044 { gold_unreachable(); }
1046 // Return the size of each GOT entry. This is only used for
1047 // laying out the incremental link info sections. A target needs
1048 // to implement this if its GOT size is different.
1050 virtual unsigned int
1051 got_entry_size() const
1052 { return size / 8; }
1054 // Create the GOT and PLT sections for an incremental update.
1055 // A target needs to implement this to support incremental linking.
1057 virtual Output_data_got_base*
1058 init_got_plt_for_update(Symbol_table*,
1060 unsigned int /* got_count */,
1061 unsigned int /* plt_count */)
1062 { gold_unreachable(); }
1064 // Reserve a GOT entry for a local symbol, and regenerate any
1065 // necessary dynamic relocations.
1067 reserve_local_got_entry(unsigned int /* got_index */,
1068 Sized_relobj<size, big_endian>* /* obj */,
1069 unsigned int /* r_sym */,
1070 unsigned int /* got_type */)
1071 { gold_unreachable(); }
1073 // Reserve a GOT entry for a global symbol, and regenerate any
1074 // necessary dynamic relocations.
1076 reserve_global_got_entry(unsigned int /* got_index */, Symbol* /* gsym */,
1077 unsigned int /* got_type */)
1078 { gold_unreachable(); }
1080 // Register an existing PLT entry for a global symbol.
1081 // A target needs to implement this to support incremental linking.
1084 register_global_plt_entry(Symbol_table*, Layout*,
1085 unsigned int /* plt_index */,
1087 { gold_unreachable(); }
1089 // Force a COPY relocation for a given symbol.
1090 // A target needs to implement this to support incremental linking.
1093 emit_copy_reloc(Symbol_table*, Symbol*, Output_section*, off_t)
1094 { gold_unreachable(); }
1096 // Apply an incremental relocation.
1099 apply_relocation(const Relocate_info<size, big_endian>* /* relinfo */,
1100 typename elfcpp::Elf_types<size>::Elf_Addr /* r_offset */,
1101 unsigned int /* r_type */,
1102 typename elfcpp::Elf_types<size>::Elf_Swxword /* r_addend */,
1103 const Symbol* /* gsym */,
1104 unsigned char* /* view */,
1105 typename elfcpp::Elf_types<size>::Elf_Addr /* address */,
1106 section_size_type /* view_size */)
1107 { gold_unreachable(); }
1109 // Handle target specific gc actions when adding a gc reference from
1110 // SRC_OBJ, SRC_SHNDX to a location specified by DST_OBJ, DST_SHNDX
1113 gc_add_reference(Symbol_table* symtab,
1115 unsigned int src_shndx,
1117 unsigned int dst_shndx,
1118 typename elfcpp::Elf_types<size>::Elf_Addr dst_off) const
1120 this->do_gc_add_reference(symtab, src_obj, src_shndx,
1121 dst_obj, dst_shndx, dst_off);
1124 // Return the r_sym field from a relocation.
1125 // Most targets can use the default version of this routine,
1126 // but some targets have a non-standard r_info field, and will
1127 // need to provide a target-specific version.
1128 virtual unsigned int
1129 get_r_sym(const unsigned char* preloc) const
1131 // Since REL and RELA relocs share the same structure through
1132 // the r_info field, we can just use REL here.
1133 elfcpp::Rel<size, big_endian> rel(preloc);
1134 return elfcpp::elf_r_sym<size>(rel.get_r_info());
1138 Sized_target(const Target::Target_info* pti)
1141 gold_assert(pti->size == size);
1142 gold_assert(pti->is_big_endian ? big_endian : !big_endian);
1145 // Set the EI_OSABI field if requested.
1147 do_adjust_elf_header(unsigned char*, int);
1149 // Handle target specific gc actions when adding a gc reference.
1151 do_gc_add_reference(Symbol_table*, Relobj*, unsigned int,
1152 Relobj*, unsigned int,
1153 typename elfcpp::Elf_types<size>::Elf_Addr) const
1157 do_function_location(Symbol_location*) const
1161 } // End namespace gold.
1163 #endif // !defined(GOLD_TARGET_H)