1 // object.h -- support for an object file for linking in gold -*- C++ -*-
3 // Copyright 2006, 2007, 2008 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.
30 #include "elfcpp_file.h"
37 class General_options;
42 class Output_symtab_xindex;
44 class Object_merge_map;
45 class Relocatable_relocs;
47 template<typename Stringpool_char>
48 class Stringpool_template;
50 // Data to pass from read_symbols() to add_symbols().
52 struct Read_symbols_data
55 File_view* section_headers;
57 File_view* section_names;
58 // Size of section name data in bytes.
59 section_size_type section_names_size;
62 // Size of symbol data in bytes.
63 section_size_type symbols_size;
64 // Offset of external symbols within symbol data. This structure
65 // sometimes contains only external symbols, in which case this will
66 // be zero. Sometimes it contains all symbols.
67 section_offset_type external_symbols_offset;
69 File_view* symbol_names;
70 // Size of symbol name data in bytes.
71 section_size_type symbol_names_size;
73 // Version information. This is only used on dynamic objects.
74 // Version symbol data (from SHT_GNU_versym section).
76 section_size_type versym_size;
77 // Version definition data (from SHT_GNU_verdef section).
79 section_size_type verdef_size;
80 unsigned int verdef_info;
81 // Needed version data (from SHT_GNU_verneed section).
83 section_size_type verneed_size;
84 unsigned int verneed_info;
87 // Information used to print error messages.
89 struct Symbol_location_info
91 std::string source_file;
92 std::string enclosing_symbol_name;
96 // Data about a single relocation section. This is read in
97 // read_relocs and processed in scan_relocs.
101 // Index of reloc section.
102 unsigned int reloc_shndx;
103 // Index of section that relocs apply to.
104 unsigned int data_shndx;
105 // Contents of reloc section.
107 // Reloc section type.
108 unsigned int sh_type;
109 // Number of reloc entries.
112 Output_section* output_section;
113 // Whether this section has special handling for offsets.
114 bool needs_special_offset_handling;
115 // Whether the data section is allocated (has the SHF_ALLOC flag set).
116 bool is_data_section_allocated;
119 // Relocations in an object file. This is read in read_relocs and
120 // processed in scan_relocs.
122 struct Read_relocs_data
124 typedef std::vector<Section_relocs> Relocs_list;
127 // The local symbols.
128 File_view* local_symbols;
131 // The Xindex class manages section indexes for objects with more than
137 Xindex(int large_shndx_offset)
138 : large_shndx_offset_(large_shndx_offset), symtab_xindex_()
141 // Initialize the symtab_xindex_ array, given the object and the
142 // section index of the symbol table to use.
143 template<int size, bool big_endian>
145 initialize_symtab_xindex(Object*, unsigned int symtab_shndx);
147 // Read in the symtab_xindex_ array, given its section index.
148 // PSHDRS may optionally point to the section headers.
149 template<int size, bool big_endian>
151 read_symtab_xindex(Object*, unsigned int xindex_shndx,
152 const unsigned char* pshdrs);
154 // Symbol SYMNDX in OBJECT has a section of SHN_XINDEX; return the
155 // real section index.
157 sym_xindex_to_shndx(Object* object, unsigned int symndx);
160 // The type of the array giving the real section index for symbols
161 // whose st_shndx field holds SHN_XINDEX.
162 typedef std::vector<unsigned int> Symtab_xindex;
164 // Adjust a section index if necessary. This should only be called
165 // for ordinary section indexes.
167 adjust_shndx(unsigned int shndx)
169 if (shndx >= elfcpp::SHN_LORESERVE)
170 shndx += this->large_shndx_offset_;
174 // Adjust to apply to large section indexes.
175 int large_shndx_offset_;
176 // The data from the SHT_SYMTAB_SHNDX section.
177 Symtab_xindex symtab_xindex_;
180 // Object is an abstract base class which represents either a 32-bit
181 // or a 64-bit input object. This can be a regular object file
182 // (ET_REL) or a shared object (ET_DYN).
187 // NAME is the name of the object as we would report it to the user
188 // (e.g., libfoo.a(bar.o) if this is in an archive. INPUT_FILE is
189 // used to read the file. OFFSET is the offset within the input
190 // file--0 for a .o or .so file, something else for a .a file.
191 Object(const std::string& name, Input_file* input_file, bool is_dynamic,
193 : name_(name), input_file_(input_file), offset_(offset), shnum_(-1U),
194 is_dynamic_(is_dynamic), target_(NULL), xindex_(NULL)
195 { input_file->file().add_object(); }
198 { this->input_file_->file().remove_object(); }
200 // Return the name of the object as we would report it to the tuser.
203 { return this->name_; }
205 // Get the offset into the file.
208 { return this->offset_; }
210 // Return whether this is a dynamic object.
213 { return this->is_dynamic_; }
215 // Return the target structure associated with this object.
218 { return this->target_; }
220 // Lock the underlying file.
223 { this->input_file()->file().lock(t); }
225 // Unlock the underlying file.
227 unlock(const Task* t)
228 { this->input_file()->file().unlock(t); }
230 // Return whether the underlying file is locked.
233 { return this->input_file()->file().is_locked(); }
235 // Return the token, so that the task can be queued.
238 { return this->input_file()->file().token(); }
240 // Release the underlying file.
243 { this->input_file_->file().release(); }
245 // Return whether we should just read symbols from this file.
248 { return this->input_file()->just_symbols(); }
250 // Return the sized target structure associated with this object.
251 // This is like the target method but it returns a pointer of
252 // appropriate checked type.
253 template<int size, bool big_endian>
254 Sized_target<size, big_endian>*
255 sized_target() const;
257 // Get the number of sections.
260 { return this->shnum_; }
262 // Return a view of the contents of a section. Set *PLEN to the
263 // size. CACHE is a hint as in File_read::get_view.
265 section_contents(unsigned int shndx, section_size_type* plen, bool cache);
267 // Adjust a symbol's section index as needed. SYMNDX is the index
268 // of the symbol and SHNDX is the symbol's section from
269 // get_st_shndx. This returns the section index. It sets
270 // *IS_ORDINARY to indicate whether this is a normal section index,
271 // rather than a special code between SHN_LORESERVE and
274 adjust_sym_shndx(unsigned int symndx, unsigned int shndx, bool* is_ordinary)
276 if (shndx < elfcpp::SHN_LORESERVE)
278 else if (shndx == elfcpp::SHN_XINDEX)
280 if (this->xindex_ == NULL)
281 this->xindex_ = this->do_initialize_xindex();
282 shndx = this->xindex_->sym_xindex_to_shndx(this, symndx);
286 *is_ordinary = false;
290 // Return the size of a section given a section index.
292 section_size(unsigned int shndx)
293 { return this->do_section_size(shndx); }
295 // Return the name of a section given a section index.
297 section_name(unsigned int shndx)
298 { return this->do_section_name(shndx); }
300 // Return the section flags given a section index.
302 section_flags(unsigned int shndx)
303 { return this->do_section_flags(shndx); }
305 // Return the section address given a section index.
307 section_address(unsigned int shndx)
308 { return this->do_section_address(shndx); }
310 // Return the section type given a section index.
312 section_type(unsigned int shndx)
313 { return this->do_section_type(shndx); }
315 // Return the section link field given a section index.
317 section_link(unsigned int shndx)
318 { return this->do_section_link(shndx); }
320 // Return the section info field given a section index.
322 section_info(unsigned int shndx)
323 { return this->do_section_info(shndx); }
325 // Return the required section alignment given a section index.
327 section_addralign(unsigned int shndx)
328 { return this->do_section_addralign(shndx); }
330 // Read the symbol information.
332 read_symbols(Read_symbols_data* sd)
333 { return this->do_read_symbols(sd); }
335 // Pass sections which should be included in the link to the Layout
336 // object, and record where the sections go in the output file.
338 layout(Symbol_table* symtab, Layout* layout, Read_symbols_data* sd)
339 { this->do_layout(symtab, layout, sd); }
341 // Add symbol information to the global symbol table.
343 add_symbols(Symbol_table* symtab, Read_symbols_data* sd)
344 { this->do_add_symbols(symtab, sd); }
346 // Functions and types for the elfcpp::Elf_file interface. This
347 // permit us to use Object as the File template parameter for
350 // The View class is returned by view. It must support a single
351 // method, data(). This is trivial, because get_view does what we
356 View(const unsigned char* p)
365 const unsigned char* p_;
370 view(off_t file_offset, section_size_type data_size)
371 { return View(this->get_view(file_offset, data_size, true, true)); }
375 error(const char* format, ...) const ATTRIBUTE_PRINTF_2;
377 // A location in the file.
383 Location(off_t fo, section_size_type ds)
384 : file_offset(fo), data_size(ds)
388 // Get a View given a Location.
389 View view(Location loc)
390 { return View(this->get_view(loc.file_offset, loc.data_size, true, true)); }
392 // Get a view into the underlying file.
394 get_view(off_t start, section_size_type size, bool aligned, bool cache)
396 return this->input_file()->file().get_view(this->offset_, start, size,
400 // Get a lasting view into the underlying file.
402 get_lasting_view(off_t start, section_size_type size, bool aligned,
405 return this->input_file()->file().get_lasting_view(this->offset_, start,
406 size, aligned, cache);
409 // Read data from the underlying file.
411 read(off_t start, section_size_type size, void* p) const
412 { this->input_file()->file().read(start + this->offset_, size, p); }
414 // Read multiple data from the underlying file.
416 read_multiple(const File_read::Read_multiple& rm)
417 { this->input_file()->file().read_multiple(this->offset_, rm); }
419 // Stop caching views in the underlying file.
421 clear_view_cache_marks()
422 { this->input_file()->file().clear_view_cache_marks(); }
425 // Read the symbols--implemented by child class.
427 do_read_symbols(Read_symbols_data*) = 0;
429 // Lay out sections--implemented by child class.
431 do_layout(Symbol_table*, Layout*, Read_symbols_data*) = 0;
433 // Add symbol information to the global symbol table--implemented by
436 do_add_symbols(Symbol_table*, Read_symbols_data*) = 0;
438 // Return the location of the contents of a section. Implemented by
441 do_section_contents(unsigned int shndx) = 0;
443 // Get the size of a section--implemented by child class.
445 do_section_size(unsigned int shndx) = 0;
447 // Get the name of a section--implemented by child class.
449 do_section_name(unsigned int shndx) = 0;
451 // Get section flags--implemented by child class.
453 do_section_flags(unsigned int shndx) = 0;
455 // Get section address--implemented by child class.
457 do_section_address(unsigned int shndx) = 0;
459 // Get section type--implemented by child class.
461 do_section_type(unsigned int shndx) = 0;
463 // Get section link field--implemented by child class.
465 do_section_link(unsigned int shndx) = 0;
467 // Get section info field--implemented by child class.
469 do_section_info(unsigned int shndx) = 0;
471 // Get section alignment--implemented by child class.
473 do_section_addralign(unsigned int shndx) = 0;
475 // Return the Xindex structure to use.
477 do_initialize_xindex() = 0;
479 // Get the file. We pass on const-ness.
482 { return this->input_file_; }
486 { return this->input_file_; }
490 set_target(int machine, int size, bool big_endian, int osabi,
493 // Set the number of sections.
496 { this->shnum_ = shnum; }
498 // Functions used by both Sized_relobj and Sized_dynobj.
500 // Read the section data into a Read_symbols_data object.
501 template<int size, bool big_endian>
503 read_section_data(elfcpp::Elf_file<size, big_endian, Object>*,
506 // Let the child class initialize the xindex object directly.
508 set_xindex(Xindex* xindex)
510 gold_assert(this->xindex_ == NULL);
511 this->xindex_ = xindex;
514 // If NAME is the name of a special .gnu.warning section, arrange
515 // for the warning to be issued. SHNDX is the section index.
516 // Return whether it is a warning section.
518 handle_gnu_warning_section(const char* name, unsigned int shndx,
522 // This class may not be copied.
523 Object(const Object&);
524 Object& operator=(const Object&);
526 // Name of object as printed to user.
528 // For reading the file.
529 Input_file* input_file_;
530 // Offset within the file--0 for an object file, non-0 for an
533 // Number of input sections.
535 // Whether this is a dynamic object.
537 // Target functions--may be NULL if the target is not known.
539 // Many sections for objects with more than SHN_LORESERVE sections.
543 // Implement sized_target inline for efficiency. This approach breaks
544 // static type checking, but is made safe using asserts.
546 template<int size, bool big_endian>
547 inline Sized_target<size, big_endian>*
548 Object::sized_target() const
550 gold_assert(this->target_->get_size() == size);
551 gold_assert(this->target_->is_big_endian() ? big_endian : !big_endian);
552 return static_cast<Sized_target<size, big_endian>*>(this->target_);
555 // A regular object (ET_REL). This is an abstract base class itself.
556 // The implementation is the template class Sized_relobj.
558 class Relobj : public Object
561 Relobj(const std::string& name, Input_file* input_file, off_t offset = 0)
562 : Object(name, input_file, false, offset),
564 map_to_relocatable_relocs_(NULL),
565 object_merge_map_(NULL),
566 relocs_must_follow_section_writes_(false)
571 read_relocs(Read_relocs_data* rd)
572 { return this->do_read_relocs(rd); }
574 // Scan the relocs and adjust the symbol table.
576 scan_relocs(const General_options& options, Symbol_table* symtab,
577 Layout* layout, Read_relocs_data* rd)
578 { return this->do_scan_relocs(options, symtab, layout, rd); }
580 // The number of local symbols in the input symbol table.
582 local_symbol_count() const
583 { return this->do_local_symbol_count(); }
585 // Initial local symbol processing: count the number of local symbols
586 // in the output symbol table and dynamic symbol table; add local symbol
587 // names to *POOL and *DYNPOOL.
589 count_local_symbols(Stringpool_template<char>* pool,
590 Stringpool_template<char>* dynpool)
591 { return this->do_count_local_symbols(pool, dynpool); }
593 // Set the values of the local symbols, set the output symbol table
594 // indexes for the local variables, and set the offset where local
595 // symbol information will be stored. Returns the new local symbol index.
597 finalize_local_symbols(unsigned int index, off_t off)
598 { return this->do_finalize_local_symbols(index, off); }
600 // Set the output dynamic symbol table indexes for the local variables.
602 set_local_dynsym_indexes(unsigned int index)
603 { return this->do_set_local_dynsym_indexes(index); }
605 // Set the offset where local dynamic symbol information will be stored.
607 set_local_dynsym_offset(off_t off)
608 { return this->do_set_local_dynsym_offset(off); }
610 // Relocate the input sections and write out the local symbols.
612 relocate(const General_options& options, const Symbol_table* symtab,
613 const Layout* layout, Output_file* of)
614 { return this->do_relocate(options, symtab, layout, of); }
616 // Return whether an input section is being included in the link.
618 is_section_included(unsigned int shndx) const
620 gold_assert(shndx < this->map_to_output_.size());
621 return this->map_to_output_[shndx].output_section != NULL;
624 // Return whether an input section requires special
625 // handling--whether it is not simply mapped from the input file to
628 is_section_specially_mapped(unsigned int shndx) const
630 gold_assert(shndx < this->map_to_output_.size());
631 return (this->map_to_output_[shndx].output_section != NULL
632 && this->map_to_output_[shndx].offset == -1);
635 // Given a section index, return the corresponding Output_section
636 // (which will be NULL if the section is not included in the link)
637 // and set *POFF to the offset within that section. *POFF will be
638 // set to -1 if the section requires special handling.
639 inline Output_section*
640 output_section(unsigned int shndx, section_offset_type* poff) const;
642 // Set the offset of an input section within its output section.
644 set_section_offset(unsigned int shndx, section_offset_type off)
646 gold_assert(shndx < this->map_to_output_.size());
647 this->map_to_output_[shndx].offset = off;
650 // Return true if we need to wait for output sections to be written
651 // before we can apply relocations. This is true if the object has
652 // any relocations for sections which require special handling, such
653 // as the exception frame section.
655 relocs_must_follow_section_writes() const
656 { return this->relocs_must_follow_section_writes_; }
658 // Return the object merge map.
661 { return this->object_merge_map_; }
663 // Set the object merge map.
665 set_merge_map(Object_merge_map* object_merge_map)
667 gold_assert(this->object_merge_map_ == NULL);
668 this->object_merge_map_ = object_merge_map;
671 // Record the relocatable reloc info for an input reloc section.
673 set_relocatable_relocs(unsigned int reloc_shndx, Relocatable_relocs* rr)
675 gold_assert(reloc_shndx < this->shnum());
676 (*this->map_to_relocatable_relocs_)[reloc_shndx] = rr;
679 // Get the relocatable reloc info for an input reloc section.
681 relocatable_relocs(unsigned int reloc_shndx)
683 gold_assert(reloc_shndx < this->shnum());
684 return (*this->map_to_relocatable_relocs_)[reloc_shndx];
688 // What we need to know to map an input section to an output
689 // section. We keep an array of these, one for each input section,
690 // indexed by the input section number.
693 // The output section. This is NULL if the input section is to be
695 Output_section* output_section;
696 // The offset within the output section. This is -1 if the
697 // section requires special handling.
698 section_offset_type offset;
701 // Read the relocs--implemented by child class.
703 do_read_relocs(Read_relocs_data*) = 0;
705 // Scan the relocs--implemented by child class.
707 do_scan_relocs(const General_options&, Symbol_table*, Layout*,
708 Read_relocs_data*) = 0;
710 // Return the number of local symbols--implemented by child class.
712 do_local_symbol_count() const = 0;
714 // Count local symbols--implemented by child class.
716 do_count_local_symbols(Stringpool_template<char>*,
717 Stringpool_template<char>*) = 0;
719 // Finalize the local symbols. Set the output symbol table indexes
720 // for the local variables, and set the offset where local symbol
721 // information will be stored.
723 do_finalize_local_symbols(unsigned int, off_t) = 0;
725 // Set the output dynamic symbol table indexes for the local variables.
727 do_set_local_dynsym_indexes(unsigned int) = 0;
729 // Set the offset where local dynamic symbol information will be stored.
731 do_set_local_dynsym_offset(off_t) = 0;
733 // Relocate the input sections and write out the local
734 // symbols--implemented by child class.
736 do_relocate(const General_options& options, const Symbol_table* symtab,
737 const Layout*, Output_file* of) = 0;
739 // Return the vector mapping input sections to output sections.
740 std::vector<Map_to_output>&
742 { return this->map_to_output_; }
744 const std::vector<Map_to_output>&
745 map_to_output() const
746 { return this->map_to_output_; }
748 // Set the size of the relocatable relocs array.
750 size_relocatable_relocs()
752 this->map_to_relocatable_relocs_ =
753 new std::vector<Relocatable_relocs*>(this->shnum());
756 // Record that we must wait for the output sections to be written
757 // before applying relocations.
759 set_relocs_must_follow_section_writes()
760 { this->relocs_must_follow_section_writes_ = true; }
763 // Mapping from input sections to output section.
764 std::vector<Map_to_output> map_to_output_;
765 // Mapping from input section index to the information recorded for
766 // the relocations. This is only used for a relocatable link.
767 std::vector<Relocatable_relocs*>* map_to_relocatable_relocs_;
768 // Mappings for merge sections. This is managed by the code in the
770 Object_merge_map* object_merge_map_;
771 // Whether we need to wait for output sections to be written before
772 // we can apply relocations.
773 bool relocs_must_follow_section_writes_;
776 // Implement Object::output_section inline for efficiency.
777 inline Output_section*
778 Relobj::output_section(unsigned int shndx, section_offset_type* poff) const
780 gold_assert(shndx < this->map_to_output_.size());
781 const Map_to_output& mo(this->map_to_output_[shndx]);
783 return mo.output_section;
786 // This class is used to handle relocations against a section symbol
787 // in an SHF_MERGE section. For such a symbol, we need to know the
788 // addend of the relocation before we can determine the final value.
789 // The addend gives us the location in the input section, and we can
790 // determine how it is mapped to the output section. For a
791 // non-section symbol, we apply the addend to the final value of the
792 // symbol; that is done in finalize_local_symbols, and does not use
796 class Merged_symbol_value
799 typedef typename elfcpp::Elf_types<size>::Elf_Addr Value;
801 // We use a hash table to map offsets in the input section to output
803 typedef Unordered_map<section_offset_type, Value> Output_addresses;
805 Merged_symbol_value(Value input_value, Value output_start_address)
806 : input_value_(input_value), output_start_address_(output_start_address),
810 // Initialize the hash table.
812 initialize_input_to_output_map(const Relobj*, unsigned int input_shndx);
814 // Release the hash table to save space.
816 free_input_to_output_map()
817 { this->output_addresses_.clear(); }
819 // Get the output value corresponding to an addend. The object and
820 // input section index are passed in because the caller will have
821 // them; otherwise we could store them here.
823 value(const Relobj* object, unsigned int input_shndx, Value addend) const
825 Value input_offset = this->input_value_ + addend;
826 typename Output_addresses::const_iterator p =
827 this->output_addresses_.find(input_offset);
828 if (p != this->output_addresses_.end())
831 return this->value_from_output_section(object, input_shndx, input_offset);
835 // Get the output value for an input offset if we couldn't find it
836 // in the hash table.
838 value_from_output_section(const Relobj*, unsigned int input_shndx,
839 Value input_offset) const;
841 // The value of the section symbol in the input file. This is
842 // normally zero, but could in principle be something else.
844 // The start address of this merged section in the output file.
845 Value output_start_address_;
846 // A hash table which maps offsets in the input section to output
847 // addresses. This only maps specific offsets, not all offsets.
848 Output_addresses output_addresses_;
851 // This POD class is holds the value of a symbol. This is used for
852 // local symbols, and for all symbols during relocation processing.
853 // For special sections, such as SHF_MERGE sections, this calls a
854 // function to get the final symbol value.
860 typedef typename elfcpp::Elf_types<size>::Elf_Addr Value;
863 : output_symtab_index_(0), output_dynsym_index_(-1U), input_shndx_(0),
864 is_ordinary_shndx_(false), is_section_symbol_(false),
865 is_tls_symbol_(false), has_output_value_(true)
866 { this->u_.value = 0; }
868 // Get the value of this symbol. OBJECT is the object in which this
869 // symbol is defined, and ADDEND is an addend to add to the value.
870 template<bool big_endian>
872 value(const Sized_relobj<size, big_endian>* object, Value addend) const
874 if (this->has_output_value_)
875 return this->u_.value + addend;
878 gold_assert(this->is_ordinary_shndx_);
879 return this->u_.merged_symbol_value->value(object, this->input_shndx_,
884 // Set the value of this symbol in the output symbol table.
886 set_output_value(Value value)
887 { this->u_.value = value; }
889 // For a section symbol in a merged section, we need more
892 set_merged_symbol_value(Merged_symbol_value<size>* msv)
894 gold_assert(this->is_section_symbol_);
895 this->has_output_value_ = false;
896 this->u_.merged_symbol_value = msv;
899 // Initialize the input to output map for a section symbol in a
900 // merged section. We also initialize the value of a non-section
901 // symbol in a merged section.
903 initialize_input_to_output_map(const Relobj* object)
905 if (!this->has_output_value_)
907 gold_assert(this->is_section_symbol_ && this->is_ordinary_shndx_);
908 Merged_symbol_value<size>* msv = this->u_.merged_symbol_value;
909 msv->initialize_input_to_output_map(object, this->input_shndx_);
913 // Free the input to output map for a section symbol in a merged
916 free_input_to_output_map()
918 if (!this->has_output_value_)
919 this->u_.merged_symbol_value->free_input_to_output_map();
922 // Set the value of the symbol from the input file. This is only
923 // called by count_local_symbols, to communicate the value to
924 // finalize_local_symbols.
926 set_input_value(Value value)
927 { this->u_.value = value; }
929 // Return the input value. This is only called by
930 // finalize_local_symbols.
933 { return this->u_.value; }
935 // Return whether this symbol should go into the output symbol
938 needs_output_symtab_entry() const
939 { return this->output_symtab_index_ != -1U; }
941 // Return the index in the output symbol table.
943 output_symtab_index() const
945 gold_assert(this->output_symtab_index_ != 0);
946 return this->output_symtab_index_;
949 // Set the index in the output symbol table.
951 set_output_symtab_index(unsigned int i)
953 gold_assert(this->output_symtab_index_ == 0);
954 this->output_symtab_index_ = i;
957 // Record that this symbol should not go into the output symbol
960 set_no_output_symtab_entry()
962 gold_assert(this->output_symtab_index_ == 0);
963 this->output_symtab_index_ = -1U;
966 // Set the index in the output dynamic symbol table.
968 set_needs_output_dynsym_entry()
970 gold_assert(!this->is_section_symbol());
971 this->output_dynsym_index_ = 0;
974 // Return whether this symbol should go into the output symbol
977 needs_output_dynsym_entry() const
979 return this->output_dynsym_index_ != -1U;
982 // Record that this symbol should go into the dynamic symbol table.
984 set_output_dynsym_index(unsigned int i)
986 gold_assert(this->output_dynsym_index_ == 0);
987 this->output_dynsym_index_ = i;
990 // Return the index in the output dynamic symbol table.
992 output_dynsym_index() const
994 gold_assert(this->output_dynsym_index_ != 0
995 && this->output_dynsym_index_ != -1U);
996 return this->output_dynsym_index_;
999 // Set the index of the input section in the input file.
1001 set_input_shndx(unsigned int i, bool is_ordinary)
1003 this->input_shndx_ = i;
1004 // input_shndx_ field is a bitfield, so make sure that the value
1006 gold_assert(this->input_shndx_ == i);
1007 this->is_ordinary_shndx_ = is_ordinary;
1010 // Return the index of the input section in the input file.
1012 input_shndx(bool* is_ordinary) const
1014 *is_ordinary = this->is_ordinary_shndx_;
1015 return this->input_shndx_;
1018 // Whether this is a section symbol.
1020 is_section_symbol() const
1021 { return this->is_section_symbol_; }
1023 // Record that this is a section symbol.
1025 set_is_section_symbol()
1027 gold_assert(!this->needs_output_dynsym_entry());
1028 this->is_section_symbol_ = true;
1031 // Record that this is a TLS symbol.
1034 { this->is_tls_symbol_ = true; }
1036 // Return TRUE if this is a TLS symbol.
1038 is_tls_symbol() const
1039 { return this->is_tls_symbol_; }
1042 // The index of this local symbol in the output symbol table. This
1043 // will be -1 if the symbol should not go into the symbol table.
1044 unsigned int output_symtab_index_;
1045 // The index of this local symbol in the dynamic symbol table. This
1046 // will be -1 if the symbol should not go into the symbol table.
1047 unsigned int output_dynsym_index_;
1048 // The section index in the input file in which this symbol is
1050 unsigned int input_shndx_ : 28;
1051 // Whether the section index is an ordinary index, not a special
1053 bool is_ordinary_shndx_ : 1;
1054 // Whether this is a STT_SECTION symbol.
1055 bool is_section_symbol_ : 1;
1056 // Whether this is a STT_TLS symbol.
1057 bool is_tls_symbol_ : 1;
1058 // Whether this symbol has a value for the output file. This is
1059 // normally set to true during Layout::finalize, by
1060 // finalize_local_symbols. It will be false for a section symbol in
1061 // a merge section, as for such symbols we can not determine the
1062 // value to use in a relocation until we see the addend.
1063 bool has_output_value_ : 1;
1066 // This is used if has_output_value_ is true. Between
1067 // count_local_symbols and finalize_local_symbols, this is the
1068 // value in the input file. After finalize_local_symbols, it is
1069 // the value in the output file.
1071 // This is used if has_output_value_ is false. It points to the
1072 // information we need to get the value for a merge section.
1073 Merged_symbol_value<size>* merged_symbol_value;
1077 // A GOT offset list. A symbol may have more than one GOT offset
1078 // (e.g., when mixing modules compiled with two different TLS models),
1079 // but will usually have at most one. GOT_TYPE identifies the type of
1080 // GOT entry; its values are specific to each target.
1082 class Got_offset_list
1086 : got_type_(-1U), got_offset_(0), got_next_(NULL)
1089 Got_offset_list(unsigned int got_type, unsigned int got_offset)
1090 : got_type_(got_type), got_offset_(got_offset), got_next_(NULL)
1095 if (this->got_next_ != NULL)
1097 delete this->got_next_;
1098 this->got_next_ = NULL;
1102 // Initialize the fields to their default values.
1106 this->got_type_ = -1U;
1107 this->got_offset_ = 0;
1108 this->got_next_ = NULL;
1111 // Set the offset for the GOT entry of type GOT_TYPE.
1113 set_offset(unsigned int got_type, unsigned int got_offset)
1115 if (this->got_type_ == -1U)
1117 this->got_type_ = got_type;
1118 this->got_offset_ = got_offset;
1122 for (Got_offset_list* g = this; g != NULL; g = g->got_next_)
1124 if (g->got_type_ == got_type)
1126 g->got_offset_ = got_offset;
1130 Got_offset_list* g = new Got_offset_list(got_type, got_offset);
1131 g->got_next_ = this->got_next_;
1132 this->got_next_ = g;
1136 // Return the offset for a GOT entry of type GOT_TYPE.
1138 get_offset(unsigned int got_type) const
1140 for (const Got_offset_list* g = this; g != NULL; g = g->got_next_)
1142 if (g->got_type_ == got_type)
1143 return g->got_offset_;
1149 unsigned int got_type_;
1150 unsigned int got_offset_;
1151 Got_offset_list* got_next_;
1154 // A regular object file. This is size and endian specific.
1156 template<int size, bool big_endian>
1157 class Sized_relobj : public Relobj
1160 typedef typename elfcpp::Elf_types<size>::Elf_Addr Address;
1161 typedef std::vector<Symbol*> Symbols;
1162 typedef std::vector<Symbol_value<size> > Local_values;
1164 Sized_relobj(const std::string& name, Input_file* input_file, off_t offset,
1165 const typename elfcpp::Ehdr<size, big_endian>&);
1169 // Set up the object file based on the ELF header.
1171 setup(const typename elfcpp::Ehdr<size, big_endian>&);
1173 // If SYM is the index of a global symbol in the object file's
1174 // symbol table, return the Symbol object. Otherwise, return NULL.
1176 global_symbol(unsigned int sym) const
1178 if (sym >= this->local_symbol_count_)
1180 gold_assert(sym - this->local_symbol_count_ < this->symbols_.size());
1181 return this->symbols_[sym - this->local_symbol_count_];
1186 // Return the section index of symbol SYM. Set *VALUE to its value
1187 // in the object file. Set *IS_ORDINARY if this is an ordinary
1188 // section index, not a special code between SHN_LORESERVE and
1189 // SHN_HIRESERVE. Note that for a symbol which is not defined in
1190 // this object file, this will set *VALUE to 0 and return SHN_UNDEF;
1191 // it will not return the final value of the symbol in the link.
1193 symbol_section_and_value(unsigned int sym, Address* value, bool* is_ordinary);
1195 // Return a pointer to the Symbol_value structure which holds the
1196 // value of a local symbol.
1197 const Symbol_value<size>*
1198 local_symbol(unsigned int sym) const
1200 gold_assert(sym < this->local_values_.size());
1201 return &this->local_values_[sym];
1204 // Return the index of local symbol SYM in the ordinary symbol
1205 // table. A value of -1U means that the symbol is not being output.
1207 symtab_index(unsigned int sym) const
1209 gold_assert(sym < this->local_values_.size());
1210 return this->local_values_[sym].output_symtab_index();
1213 // Return the index of local symbol SYM in the dynamic symbol
1214 // table. A value of -1U means that the symbol is not being output.
1216 dynsym_index(unsigned int sym) const
1218 gold_assert(sym < this->local_values_.size());
1219 return this->local_values_[sym].output_dynsym_index();
1222 // Return the input section index of local symbol SYM.
1224 local_symbol_input_shndx(unsigned int sym, bool* is_ordinary) const
1226 gold_assert(sym < this->local_values_.size());
1227 return this->local_values_[sym].input_shndx(is_ordinary);
1230 // Return the appropriate Sized_target structure.
1231 Sized_target<size, big_endian>*
1233 { return this->Object::sized_target<size, big_endian>(); }
1235 // Record that local symbol SYM needs a dynamic symbol entry.
1237 set_needs_output_dynsym_entry(unsigned int sym)
1239 gold_assert(sym < this->local_values_.size());
1240 this->local_values_[sym].set_needs_output_dynsym_entry();
1243 // Return whether the local symbol SYMNDX has a GOT offset.
1244 // For TLS symbols, the GOT entry will hold its tp-relative offset.
1246 local_has_got_offset(unsigned int symndx, unsigned int got_type) const
1248 Local_got_offsets::const_iterator p =
1249 this->local_got_offsets_.find(symndx);
1250 return (p != this->local_got_offsets_.end()
1251 && p->second->get_offset(got_type) != -1U);
1254 // Return the GOT offset of the local symbol SYMNDX.
1256 local_got_offset(unsigned int symndx, unsigned int got_type) const
1258 Local_got_offsets::const_iterator p =
1259 this->local_got_offsets_.find(symndx);
1260 gold_assert(p != this->local_got_offsets_.end());
1261 unsigned int off = p->second->get_offset(got_type);
1262 gold_assert(off != -1U);
1266 // Set the GOT offset of the local symbol SYMNDX to GOT_OFFSET.
1268 set_local_got_offset(unsigned int symndx, unsigned int got_type,
1269 unsigned int got_offset)
1271 Local_got_offsets::const_iterator p =
1272 this->local_got_offsets_.find(symndx);
1273 if (p != this->local_got_offsets_.end())
1274 p->second->set_offset(got_type, got_offset);
1277 Got_offset_list* g = new Got_offset_list(got_type, got_offset);
1278 std::pair<Local_got_offsets::iterator, bool> ins =
1279 this->local_got_offsets_.insert(std::make_pair(symndx, g));
1280 gold_assert(ins.second);
1284 // Return the name of the symbol that spans the given offset in the
1285 // specified section in this object. This is used only for error
1286 // messages and is not particularly efficient.
1288 get_symbol_location_info(unsigned int shndx, off_t offset,
1289 Symbol_location_info* info);
1292 // Read the symbols.
1294 do_read_symbols(Read_symbols_data*);
1296 // Return the number of local symbols.
1298 do_local_symbol_count() const
1299 { return this->local_symbol_count_; }
1301 // Lay out the input sections.
1303 do_layout(Symbol_table*, Layout*, Read_symbols_data*);
1305 // Add the symbols to the symbol table.
1307 do_add_symbols(Symbol_table*, Read_symbols_data*);
1311 do_read_relocs(Read_relocs_data*);
1313 // Scan the relocs and adjust the symbol table.
1315 do_scan_relocs(const General_options&, Symbol_table*, Layout*,
1318 // Count the local symbols.
1320 do_count_local_symbols(Stringpool_template<char>*,
1321 Stringpool_template<char>*);
1323 // Finalize the local symbols.
1325 do_finalize_local_symbols(unsigned int, off_t);
1327 // Set the offset where local dynamic symbol information will be stored.
1329 do_set_local_dynsym_indexes(unsigned int);
1331 // Set the offset where local dynamic symbol information will be stored.
1333 do_set_local_dynsym_offset(off_t);
1335 // Relocate the input sections and write out the local symbols.
1337 do_relocate(const General_options& options, const Symbol_table* symtab,
1338 const Layout*, Output_file* of);
1340 // Get the size of a section.
1342 do_section_size(unsigned int shndx)
1343 { return this->elf_file_.section_size(shndx); }
1345 // Get the name of a section.
1347 do_section_name(unsigned int shndx)
1348 { return this->elf_file_.section_name(shndx); }
1350 // Return the location of the contents of a section.
1352 do_section_contents(unsigned int shndx)
1353 { return this->elf_file_.section_contents(shndx); }
1355 // Return section flags.
1357 do_section_flags(unsigned int shndx)
1358 { return this->elf_file_.section_flags(shndx); }
1360 // Return section address.
1362 do_section_address(unsigned int shndx)
1363 { return this->elf_file_.section_addr(shndx); }
1365 // Return section type.
1367 do_section_type(unsigned int shndx)
1368 { return this->elf_file_.section_type(shndx); }
1370 // Return the section link field.
1372 do_section_link(unsigned int shndx)
1373 { return this->elf_file_.section_link(shndx); }
1375 // Return the section info field.
1377 do_section_info(unsigned int shndx)
1378 { return this->elf_file_.section_info(shndx); }
1380 // Return the section alignment.
1382 do_section_addralign(unsigned int shndx)
1383 { return this->elf_file_.section_addralign(shndx); }
1385 // Return the Xindex structure to use.
1387 do_initialize_xindex();
1391 typedef Sized_relobj<size, big_endian> This;
1392 static const int ehdr_size = elfcpp::Elf_sizes<size>::ehdr_size;
1393 static const int shdr_size = elfcpp::Elf_sizes<size>::shdr_size;
1394 static const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
1395 typedef elfcpp::Shdr<size, big_endian> Shdr;
1397 // Adjust a section index if necessary.
1399 adjust_shndx(unsigned int shndx)
1401 if (shndx >= elfcpp::SHN_LORESERVE)
1402 shndx += this->elf_file_.large_shndx_offset();
1406 // Find the SHT_SYMTAB section, given the section headers.
1408 find_symtab(const unsigned char* pshdrs);
1410 // Return whether SHDR has the right flags for a GNU style exception
1413 check_eh_frame_flags(const elfcpp::Shdr<size, big_endian>* shdr) const;
1415 // Return whether there is a section named .eh_frame which might be
1416 // a GNU style exception frame section.
1418 find_eh_frame(const unsigned char* pshdrs, const char* names,
1419 section_size_type names_size) const;
1421 // Whether to include a section group in the link.
1423 include_section_group(Symbol_table*, Layout*, unsigned int, const char*,
1424 const elfcpp::Shdr<size, big_endian>&,
1425 std::vector<bool>*);
1427 // Whether to include a linkonce section in the link.
1429 include_linkonce_section(Layout*, const char*,
1430 const elfcpp::Shdr<size, big_endian>&);
1432 // Views and sizes when relocating.
1435 unsigned char* view;
1436 typename elfcpp::Elf_types<size>::Elf_Addr address;
1438 section_size_type view_size;
1439 bool is_input_output_view;
1440 bool is_postprocessing_view;
1443 typedef std::vector<View_size> Views;
1445 // Write section data to the output file. Record the views and
1446 // sizes in VIEWS for use when relocating.
1448 write_sections(const unsigned char* pshdrs, Output_file*, Views*);
1450 // Relocate the sections in the output file.
1452 relocate_sections(const General_options& options, const Symbol_table*,
1453 const Layout*, const unsigned char* pshdrs, Views*);
1455 // Scan the input relocations for --emit-relocs.
1457 emit_relocs_scan(const General_options&, Symbol_table*, Layout*,
1458 const unsigned char* plocal_syms,
1459 const Read_relocs_data::Relocs_list::iterator&);
1461 // Scan the input relocations for --emit-relocs, templatized on the
1462 // type of the relocation section.
1463 template<int sh_type>
1465 emit_relocs_scan_reltype(const General_options&, Symbol_table*, Layout*,
1466 const unsigned char* plocal_syms,
1467 const Read_relocs_data::Relocs_list::iterator&,
1468 Relocatable_relocs*);
1470 // Emit the relocs for --emit-relocs.
1472 emit_relocs(const Relocate_info<size, big_endian>*, unsigned int,
1473 unsigned int sh_type, const unsigned char* prelocs,
1474 size_t reloc_count, Output_section*, off_t output_offset,
1475 unsigned char* view, Address address,
1476 section_size_type view_size,
1477 unsigned char* reloc_view, section_size_type reloc_view_size);
1479 // Emit the relocs for --emit-relocs, templatized on the type of the
1480 // relocation section.
1481 template<int sh_type>
1483 emit_relocs_reltype(const Relocate_info<size, big_endian>*, unsigned int,
1484 const unsigned char* prelocs, size_t reloc_count,
1485 Output_section*, off_t output_offset,
1486 unsigned char* view, Address address,
1487 section_size_type view_size,
1488 unsigned char* reloc_view,
1489 section_size_type reloc_view_size);
1491 // Initialize input to output maps for section symbols in merged
1494 initialize_input_to_output_maps();
1496 // Free the input to output maps for section symbols in merged
1499 free_input_to_output_maps();
1501 // Write out the local symbols.
1503 write_local_symbols(Output_file*,
1504 const Stringpool_template<char>*,
1505 const Stringpool_template<char>*,
1506 Output_symtab_xindex*,
1507 Output_symtab_xindex*);
1509 // Clear the local symbol information.
1511 clear_local_symbols()
1513 this->local_values_.clear();
1514 this->local_got_offsets_.clear();
1517 // The GOT offsets of local symbols. This map also stores GOT offsets
1518 // for tp-relative offsets for TLS symbols.
1519 typedef Unordered_map<unsigned int, Got_offset_list*> Local_got_offsets;
1521 // The TLS GOT offsets of local symbols. The map stores the offsets
1522 // for either a single GOT entry that holds the module index of a TLS
1523 // symbol, or a pair of GOT entries containing the module index and
1524 // dtv-relative offset.
1525 struct Tls_got_entry
1527 Tls_got_entry(int got_offset, bool have_pair)
1528 : got_offset_(got_offset),
1529 have_pair_(have_pair)
1534 typedef Unordered_map<unsigned int, Tls_got_entry> Local_tls_got_offsets;
1536 // General access to the ELF file.
1537 elfcpp::Elf_file<size, big_endian, Object> elf_file_;
1538 // Index of SHT_SYMTAB section.
1539 unsigned int symtab_shndx_;
1540 // The number of local symbols.
1541 unsigned int local_symbol_count_;
1542 // The number of local symbols which go into the output file.
1543 unsigned int output_local_symbol_count_;
1544 // The number of local symbols which go into the output file's dynamic
1546 unsigned int output_local_dynsym_count_;
1547 // The entries in the symbol table for the external symbols.
1549 // File offset for local symbols.
1550 off_t local_symbol_offset_;
1551 // File offset for local dynamic symbols.
1552 off_t local_dynsym_offset_;
1553 // Values of local symbols.
1554 Local_values local_values_;
1555 // GOT offsets for local non-TLS symbols, and tp-relative offsets
1556 // for TLS symbols, indexed by symbol number.
1557 Local_got_offsets local_got_offsets_;
1558 // Whether this object has a GNU style .eh_frame section.
1562 // A class to manage the list of all objects.
1568 : relobj_list_(), dynobj_list_(), sonames_(), system_library_directory_()
1571 // The type of the list of input relocateable objects.
1572 typedef std::vector<Relobj*> Relobj_list;
1573 typedef Relobj_list::const_iterator Relobj_iterator;
1575 // The type of the list of input dynamic objects.
1576 typedef std::vector<Dynobj*> Dynobj_list;
1577 typedef Dynobj_list::const_iterator Dynobj_iterator;
1579 // Add an object to the list. Return true if all is well, or false
1580 // if this object should be ignored.
1582 add_object(Object*);
1584 // For each dynamic object, check whether we've seen all of its
1585 // explicit dependencies.
1587 check_dynamic_dependencies() const;
1589 // Return whether an object was found in the system library
1592 found_in_system_library_directory(const Object*) const;
1594 // Iterate over all regular objects.
1597 relobj_begin() const
1598 { return this->relobj_list_.begin(); }
1602 { return this->relobj_list_.end(); }
1604 // Iterate over all dynamic objects.
1607 dynobj_begin() const
1608 { return this->dynobj_list_.begin(); }
1612 { return this->dynobj_list_.end(); }
1614 // Return whether we have seen any dynamic objects.
1617 { return !this->dynobj_list_.empty(); }
1619 // Return the number of input objects.
1621 number_of_input_objects() const
1622 { return this->relobj_list_.size() + this->dynobj_list_.size(); }
1625 Input_objects(const Input_objects&);
1626 Input_objects& operator=(const Input_objects&);
1628 // The list of ordinary objects included in the link.
1629 Relobj_list relobj_list_;
1630 // The list of dynamic objects included in the link.
1631 Dynobj_list dynobj_list_;
1632 // SONAMEs that we have seen.
1633 Unordered_set<std::string> sonames_;
1634 // The directory in which we find the libc.so.
1635 std::string system_library_directory_;
1638 // Some of the information we pass to the relocation routines. We
1639 // group this together to avoid passing a dozen different arguments.
1641 template<int size, bool big_endian>
1642 struct Relocate_info
1644 // Command line options.
1645 const General_options* options;
1647 const Symbol_table* symtab;
1649 const Layout* layout;
1650 // Object being relocated.
1651 Sized_relobj<size, big_endian>* object;
1652 // Section index of relocation section.
1653 unsigned int reloc_shndx;
1654 // Section index of section being relocated.
1655 unsigned int data_shndx;
1657 // Return a string showing the location of a relocation. This is
1658 // only used for error messages.
1660 location(size_t relnum, off_t reloffset) const;
1663 // Return an Object appropriate for the input file. P is BYTES long,
1664 // and holds the ELF header.
1667 make_elf_object(const std::string& name, Input_file*,
1668 off_t offset, const unsigned char* p,
1669 section_offset_type bytes);
1671 } // end namespace gold
1673 #endif // !defined(GOLD_OBJECT_H)