1 // layout.cc -- lay out output file sections for gold
3 // Copyright 2006, 2007, 2008, 2009, 2010, 2011 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.
34 #include "libiberty.h"
38 #include "parameters.h"
42 #include "script-sections.h"
47 #include "compressed_output.h"
48 #include "reduced_debug_output.h"
50 #include "descriptors.h"
52 #include "incremental.h"
58 // Layout::Relaxation_debug_check methods.
60 // Check that sections and special data are in reset states.
61 // We do not save states for Output_sections and special Output_data.
62 // So we check that they have not assigned any addresses or offsets.
63 // clean_up_after_relaxation simply resets their addresses and offsets.
65 Layout::Relaxation_debug_check::check_output_data_for_reset_values(
66 const Layout::Section_list& sections,
67 const Layout::Data_list& special_outputs)
69 for(Layout::Section_list::const_iterator p = sections.begin();
72 gold_assert((*p)->address_and_file_offset_have_reset_values());
74 for(Layout::Data_list::const_iterator p = special_outputs.begin();
75 p != special_outputs.end();
77 gold_assert((*p)->address_and_file_offset_have_reset_values());
80 // Save information of SECTIONS for checking later.
83 Layout::Relaxation_debug_check::read_sections(
84 const Layout::Section_list& sections)
86 for(Layout::Section_list::const_iterator p = sections.begin();
90 Output_section* os = *p;
92 info.output_section = os;
93 info.address = os->is_address_valid() ? os->address() : 0;
94 info.data_size = os->is_data_size_valid() ? os->data_size() : -1;
95 info.offset = os->is_offset_valid()? os->offset() : -1 ;
96 this->section_infos_.push_back(info);
100 // Verify SECTIONS using previously recorded information.
103 Layout::Relaxation_debug_check::verify_sections(
104 const Layout::Section_list& sections)
107 for(Layout::Section_list::const_iterator p = sections.begin();
111 Output_section* os = *p;
112 uint64_t address = os->is_address_valid() ? os->address() : 0;
113 off_t data_size = os->is_data_size_valid() ? os->data_size() : -1;
114 off_t offset = os->is_offset_valid()? os->offset() : -1 ;
116 if (i >= this->section_infos_.size())
118 gold_fatal("Section_info of %s missing.\n", os->name());
120 const Section_info& info = this->section_infos_[i];
121 if (os != info.output_section)
122 gold_fatal("Section order changed. Expecting %s but see %s\n",
123 info.output_section->name(), os->name());
124 if (address != info.address
125 || data_size != info.data_size
126 || offset != info.offset)
127 gold_fatal("Section %s changed.\n", os->name());
131 // Layout_task_runner methods.
133 // Lay out the sections. This is called after all the input objects
137 Layout_task_runner::run(Workqueue* workqueue, const Task* task)
139 off_t file_size = this->layout_->finalize(this->input_objects_,
144 // Now we know the final size of the output file and we know where
145 // each piece of information goes.
147 if (this->mapfile_ != NULL)
149 this->mapfile_->print_discarded_sections(this->input_objects_);
150 this->layout_->print_to_mapfile(this->mapfile_);
153 Output_file* of = new Output_file(parameters->options().output_file_name());
154 if (this->options_.oformat_enum() != General_options::OBJECT_FORMAT_ELF)
155 of->set_is_temporary();
158 // Queue up the final set of tasks.
159 gold::queue_final_tasks(this->options_, this->input_objects_,
160 this->symtab_, this->layout_, workqueue, of);
165 Layout::Layout(int number_of_input_files, Script_options* script_options)
166 : number_of_input_files_(number_of_input_files),
167 script_options_(script_options),
175 unattached_section_list_(),
176 special_output_list_(),
177 section_headers_(NULL),
179 relro_segment_(NULL),
181 symtab_section_(NULL),
182 symtab_xindex_(NULL),
183 dynsym_section_(NULL),
184 dynsym_xindex_(NULL),
185 dynamic_section_(NULL),
186 dynamic_symbol_(NULL),
188 eh_frame_section_(NULL),
189 eh_frame_data_(NULL),
190 added_eh_frame_data_(false),
191 eh_frame_hdr_section_(NULL),
192 build_id_note_(NULL),
196 output_file_size_(-1),
197 have_added_input_section_(false),
198 sections_are_attached_(false),
199 input_requires_executable_stack_(false),
200 input_with_gnu_stack_note_(false),
201 input_without_gnu_stack_note_(false),
202 has_static_tls_(false),
203 any_postprocessing_sections_(false),
204 resized_signatures_(false),
205 have_stabstr_section_(false),
206 incremental_inputs_(NULL),
207 record_output_section_data_from_script_(false),
208 script_output_section_data_list_(),
209 segment_states_(NULL),
210 relaxation_debug_check_(NULL)
212 // Make space for more than enough segments for a typical file.
213 // This is just for efficiency--it's OK if we wind up needing more.
214 this->segment_list_.reserve(12);
216 // We expect two unattached Output_data objects: the file header and
217 // the segment headers.
218 this->special_output_list_.reserve(2);
220 // Initialize structure needed for an incremental build.
221 if (parameters->incremental())
222 this->incremental_inputs_ = new Incremental_inputs;
224 // The section name pool is worth optimizing in all cases, because
225 // it is small, but there are often overlaps due to .rel sections.
226 this->namepool_.set_optimize();
229 // Hash a key we use to look up an output section mapping.
232 Layout::Hash_key::operator()(const Layout::Key& k) const
234 return k.first + k.second.first + k.second.second;
237 // Returns whether the given section is in the list of
238 // debug-sections-used-by-some-version-of-gdb. Currently,
239 // we've checked versions of gdb up to and including 6.7.1.
241 static const char* gdb_sections[] =
243 // ".debug_aranges", // not used by gdb as of 6.7.1
250 // ".debug_pubnames", // not used by gdb as of 6.7.1
255 static const char* lines_only_debug_sections[] =
257 // ".debug_aranges", // not used by gdb as of 6.7.1
264 // ".debug_pubnames", // not used by gdb as of 6.7.1
270 is_gdb_debug_section(const char* str)
272 // We can do this faster: binary search or a hashtable. But why bother?
273 for (size_t i = 0; i < sizeof(gdb_sections)/sizeof(*gdb_sections); ++i)
274 if (strcmp(str, gdb_sections[i]) == 0)
280 is_lines_only_debug_section(const char* str)
282 // We can do this faster: binary search or a hashtable. But why bother?
284 i < sizeof(lines_only_debug_sections)/sizeof(*lines_only_debug_sections);
286 if (strcmp(str, lines_only_debug_sections[i]) == 0)
291 // Whether to include this section in the link.
293 template<int size, bool big_endian>
295 Layout::include_section(Sized_relobj<size, big_endian>*, const char* name,
296 const elfcpp::Shdr<size, big_endian>& shdr)
298 if (shdr.get_sh_flags() & elfcpp::SHF_EXCLUDE)
301 switch (shdr.get_sh_type())
303 case elfcpp::SHT_NULL:
304 case elfcpp::SHT_SYMTAB:
305 case elfcpp::SHT_DYNSYM:
306 case elfcpp::SHT_HASH:
307 case elfcpp::SHT_DYNAMIC:
308 case elfcpp::SHT_SYMTAB_SHNDX:
311 case elfcpp::SHT_STRTAB:
312 // Discard the sections which have special meanings in the ELF
313 // ABI. Keep others (e.g., .stabstr). We could also do this by
314 // checking the sh_link fields of the appropriate sections.
315 return (strcmp(name, ".dynstr") != 0
316 && strcmp(name, ".strtab") != 0
317 && strcmp(name, ".shstrtab") != 0);
319 case elfcpp::SHT_RELA:
320 case elfcpp::SHT_REL:
321 case elfcpp::SHT_GROUP:
322 // If we are emitting relocations these should be handled
324 gold_assert(!parameters->options().relocatable()
325 && !parameters->options().emit_relocs());
328 case elfcpp::SHT_PROGBITS:
329 if (parameters->options().strip_debug()
330 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
332 if (is_debug_info_section(name))
335 if (parameters->options().strip_debug_non_line()
336 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
338 // Debugging sections can only be recognized by name.
339 if (is_prefix_of(".debug", name)
340 && !is_lines_only_debug_section(name))
343 if (parameters->options().strip_debug_gdb()
344 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
346 // Debugging sections can only be recognized by name.
347 if (is_prefix_of(".debug", name)
348 && !is_gdb_debug_section(name))
351 if (parameters->options().strip_lto_sections()
352 && !parameters->options().relocatable()
353 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
355 // Ignore LTO sections containing intermediate code.
356 if (is_prefix_of(".gnu.lto_", name))
359 // The GNU linker strips .gnu_debuglink sections, so we do too.
360 // This is a feature used to keep debugging information in
362 if (strcmp(name, ".gnu_debuglink") == 0)
371 // Return an output section named NAME, or NULL if there is none.
374 Layout::find_output_section(const char* name) const
376 for (Section_list::const_iterator p = this->section_list_.begin();
377 p != this->section_list_.end();
379 if (strcmp((*p)->name(), name) == 0)
384 // Return an output segment of type TYPE, with segment flags SET set
385 // and segment flags CLEAR clear. Return NULL if there is none.
388 Layout::find_output_segment(elfcpp::PT type, elfcpp::Elf_Word set,
389 elfcpp::Elf_Word clear) const
391 for (Segment_list::const_iterator p = this->segment_list_.begin();
392 p != this->segment_list_.end();
394 if (static_cast<elfcpp::PT>((*p)->type()) == type
395 && ((*p)->flags() & set) == set
396 && ((*p)->flags() & clear) == 0)
401 // Return the output section to use for section NAME with type TYPE
402 // and section flags FLAGS. NAME must be canonicalized in the string
403 // pool, and NAME_KEY is the key. IS_INTERP is true if this is the
404 // .interp section. IS_DYNAMIC_LINKER_SECTION is true if this section
405 // is used by the dynamic linker. IS_RELRO is true for a relro
406 // section. IS_LAST_RELRO is true for the last relro section.
407 // IS_FIRST_NON_RELRO is true for the first non-relro section.
410 Layout::get_output_section(const char* name, Stringpool::Key name_key,
411 elfcpp::Elf_Word type, elfcpp::Elf_Xword flags,
412 Output_section_order order, bool is_relro)
414 elfcpp::Elf_Xword lookup_flags = flags;
416 // Ignoring SHF_WRITE and SHF_EXECINSTR here means that we combine
417 // read-write with read-only sections. Some other ELF linkers do
418 // not do this. FIXME: Perhaps there should be an option
420 lookup_flags &= ~(elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR);
422 const Key key(name_key, std::make_pair(type, lookup_flags));
423 const std::pair<Key, Output_section*> v(key, NULL);
424 std::pair<Section_name_map::iterator, bool> ins(
425 this->section_name_map_.insert(v));
428 return ins.first->second;
431 // This is the first time we've seen this name/type/flags
432 // combination. For compatibility with the GNU linker, we
433 // combine sections with contents and zero flags with sections
434 // with non-zero flags. This is a workaround for cases where
435 // assembler code forgets to set section flags. FIXME: Perhaps
436 // there should be an option to control this.
437 Output_section* os = NULL;
439 if (type == elfcpp::SHT_PROGBITS)
443 Output_section* same_name = this->find_output_section(name);
444 if (same_name != NULL
445 && same_name->type() == elfcpp::SHT_PROGBITS
446 && (same_name->flags() & elfcpp::SHF_TLS) == 0)
449 else if ((flags & elfcpp::SHF_TLS) == 0)
451 elfcpp::Elf_Xword zero_flags = 0;
452 const Key zero_key(name_key, std::make_pair(type, zero_flags));
453 Section_name_map::iterator p =
454 this->section_name_map_.find(zero_key);
455 if (p != this->section_name_map_.end())
461 os = this->make_output_section(name, type, flags, order, is_relro);
463 ins.first->second = os;
468 // Pick the output section to use for section NAME, in input file
469 // RELOBJ, with type TYPE and flags FLAGS. RELOBJ may be NULL for a
470 // linker created section. IS_INPUT_SECTION is true if we are
471 // choosing an output section for an input section found in a input
472 // file. IS_INTERP is true if this is the .interp section.
473 // IS_DYNAMIC_LINKER_SECTION is true if this section is used by the
474 // dynamic linker. IS_RELRO is true for a relro section.
475 // IS_LAST_RELRO is true for the last relro section.
476 // IS_FIRST_NON_RELRO is true for the first non-relro section. This
477 // will return NULL if the input section should be discarded.
480 Layout::choose_output_section(const Relobj* relobj, const char* name,
481 elfcpp::Elf_Word type, elfcpp::Elf_Xword flags,
482 bool is_input_section, Output_section_order order,
485 // We should not see any input sections after we have attached
486 // sections to segments.
487 gold_assert(!is_input_section || !this->sections_are_attached_);
489 // Some flags in the input section should not be automatically
490 // copied to the output section.
491 flags &= ~ (elfcpp::SHF_INFO_LINK
494 | elfcpp::SHF_STRINGS);
496 // We only clear the SHF_LINK_ORDER flag in for
497 // a non-relocatable link.
498 if (!parameters->options().relocatable())
499 flags &= ~elfcpp::SHF_LINK_ORDER;
501 if (this->script_options_->saw_sections_clause())
503 // We are using a SECTIONS clause, so the output section is
504 // chosen based only on the name.
506 Script_sections* ss = this->script_options_->script_sections();
507 const char* file_name = relobj == NULL ? NULL : relobj->name().c_str();
508 Output_section** output_section_slot;
509 Script_sections::Section_type script_section_type;
510 const char* orig_name = name;
511 name = ss->output_section_name(file_name, name, &output_section_slot,
512 &script_section_type);
515 gold_debug(DEBUG_SCRIPT, _("Unable to create output section '%s' "
516 "because it is not allowed by the "
517 "SECTIONS clause of the linker script"),
519 // The SECTIONS clause says to discard this input section.
523 // We can only handle script section types ST_NONE and ST_NOLOAD.
524 switch (script_section_type)
526 case Script_sections::ST_NONE:
528 case Script_sections::ST_NOLOAD:
529 flags &= elfcpp::SHF_ALLOC;
535 // If this is an orphan section--one not mentioned in the linker
536 // script--then OUTPUT_SECTION_SLOT will be NULL, and we do the
537 // default processing below.
539 if (output_section_slot != NULL)
541 if (*output_section_slot != NULL)
543 (*output_section_slot)->update_flags_for_input_section(flags);
544 return *output_section_slot;
547 // We don't put sections found in the linker script into
548 // SECTION_NAME_MAP_. That keeps us from getting confused
549 // if an orphan section is mapped to a section with the same
550 // name as one in the linker script.
552 name = this->namepool_.add(name, false, NULL);
554 Output_section* os = this->make_output_section(name, type, flags,
557 os->set_found_in_sections_clause();
559 // Special handling for NOLOAD sections.
560 if (script_section_type == Script_sections::ST_NOLOAD)
564 // The constructor of Output_section sets addresses of non-ALLOC
565 // sections to 0 by default. We don't want that for NOLOAD
566 // sections even if they have no SHF_ALLOC flag.
567 if ((os->flags() & elfcpp::SHF_ALLOC) == 0
568 && os->is_address_valid())
570 gold_assert(os->address() == 0
571 && !os->is_offset_valid()
572 && !os->is_data_size_valid());
573 os->reset_address_and_file_offset();
577 *output_section_slot = os;
582 // FIXME: Handle SHF_OS_NONCONFORMING somewhere.
584 // Turn NAME from the name of the input section into the name of the
587 size_t len = strlen(name);
589 && !this->script_options_->saw_sections_clause()
590 && !parameters->options().relocatable())
591 name = Layout::output_section_name(name, &len);
593 Stringpool::Key name_key;
594 name = this->namepool_.add_with_length(name, len, true, &name_key);
596 // Find or make the output section. The output section is selected
597 // based on the section name, type, and flags.
598 return this->get_output_section(name, name_key, type, flags, order, is_relro);
601 // Return the output section to use for input section SHNDX, with name
602 // NAME, with header HEADER, from object OBJECT. RELOC_SHNDX is the
603 // index of a relocation section which applies to this section, or 0
604 // if none, or -1U if more than one. RELOC_TYPE is the type of the
605 // relocation section if there is one. Set *OFF to the offset of this
606 // input section without the output section. Return NULL if the
607 // section should be discarded. Set *OFF to -1 if the section
608 // contents should not be written directly to the output file, but
609 // will instead receive special handling.
611 template<int size, bool big_endian>
613 Layout::layout(Sized_relobj<size, big_endian>* object, unsigned int shndx,
614 const char* name, const elfcpp::Shdr<size, big_endian>& shdr,
615 unsigned int reloc_shndx, unsigned int, off_t* off)
619 if (!this->include_section(object, name, shdr))
624 // Sometimes .init_array*, .preinit_array* and .fini_array* do not have
625 // correct section types. Force them here.
626 elfcpp::Elf_Word sh_type = shdr.get_sh_type();
627 if (sh_type == elfcpp::SHT_PROGBITS)
629 static const char init_array_prefix[] = ".init_array";
630 static const char preinit_array_prefix[] = ".preinit_array";
631 static const char fini_array_prefix[] = ".fini_array";
632 static size_t init_array_prefix_size = sizeof(init_array_prefix) - 1;
633 static size_t preinit_array_prefix_size =
634 sizeof(preinit_array_prefix) - 1;
635 static size_t fini_array_prefix_size = sizeof(fini_array_prefix) - 1;
637 if (strncmp(name, init_array_prefix, init_array_prefix_size) == 0)
638 sh_type = elfcpp::SHT_INIT_ARRAY;
639 else if (strncmp(name, preinit_array_prefix, preinit_array_prefix_size)
641 sh_type = elfcpp::SHT_PREINIT_ARRAY;
642 else if (strncmp(name, fini_array_prefix, fini_array_prefix_size) == 0)
643 sh_type = elfcpp::SHT_FINI_ARRAY;
646 // In a relocatable link a grouped section must not be combined with
647 // any other sections.
648 if (parameters->options().relocatable()
649 && (shdr.get_sh_flags() & elfcpp::SHF_GROUP) != 0)
651 name = this->namepool_.add(name, true, NULL);
652 os = this->make_output_section(name, sh_type, shdr.get_sh_flags(),
653 ORDER_INVALID, false);
657 os = this->choose_output_section(object, name, sh_type,
658 shdr.get_sh_flags(), true,
659 ORDER_INVALID, false);
664 // By default the GNU linker sorts input sections whose names match
665 // .ctor.*, .dtor.*, .init_array.*, or .fini_array.*. The sections
666 // are sorted by name. This is used to implement constructor
667 // priority ordering. We are compatible.
668 if (!this->script_options_->saw_sections_clause()
669 && (is_prefix_of(".ctors.", name)
670 || is_prefix_of(".dtors.", name)
671 || is_prefix_of(".init_array.", name)
672 || is_prefix_of(".fini_array.", name)))
673 os->set_must_sort_attached_input_sections();
675 // FIXME: Handle SHF_LINK_ORDER somewhere.
677 elfcpp::Elf_Xword orig_flags = os->flags();
679 *off = os->add_input_section(this, object, shndx, name, shdr, reloc_shndx,
680 this->script_options_->saw_sections_clause());
682 // If the flags changed, we may have to change the order.
683 if ((orig_flags & elfcpp::SHF_ALLOC) != 0)
685 orig_flags &= (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR);
686 elfcpp::Elf_Xword new_flags =
687 os->flags() & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR);
688 if (orig_flags != new_flags)
689 os->set_order(this->default_section_order(os, false));
692 this->have_added_input_section_ = true;
697 // Handle a relocation section when doing a relocatable link.
699 template<int size, bool big_endian>
701 Layout::layout_reloc(Sized_relobj<size, big_endian>* object,
703 const elfcpp::Shdr<size, big_endian>& shdr,
704 Output_section* data_section,
705 Relocatable_relocs* rr)
707 gold_assert(parameters->options().relocatable()
708 || parameters->options().emit_relocs());
710 int sh_type = shdr.get_sh_type();
713 if (sh_type == elfcpp::SHT_REL)
715 else if (sh_type == elfcpp::SHT_RELA)
719 name += data_section->name();
721 // In a relocatable link relocs for a grouped section must not be
722 // combined with other reloc sections.
724 if (!parameters->options().relocatable()
725 || (data_section->flags() & elfcpp::SHF_GROUP) == 0)
726 os = this->choose_output_section(object, name.c_str(), sh_type,
727 shdr.get_sh_flags(), false,
728 ORDER_INVALID, false);
731 const char* n = this->namepool_.add(name.c_str(), true, NULL);
732 os = this->make_output_section(n, sh_type, shdr.get_sh_flags(),
733 ORDER_INVALID, false);
736 os->set_should_link_to_symtab();
737 os->set_info_section(data_section);
739 Output_section_data* posd;
740 if (sh_type == elfcpp::SHT_REL)
742 os->set_entsize(elfcpp::Elf_sizes<size>::rel_size);
743 posd = new Output_relocatable_relocs<elfcpp::SHT_REL,
747 else if (sh_type == elfcpp::SHT_RELA)
749 os->set_entsize(elfcpp::Elf_sizes<size>::rela_size);
750 posd = new Output_relocatable_relocs<elfcpp::SHT_RELA,
757 os->add_output_section_data(posd);
758 rr->set_output_data(posd);
763 // Handle a group section when doing a relocatable link.
765 template<int size, bool big_endian>
767 Layout::layout_group(Symbol_table* symtab,
768 Sized_relobj<size, big_endian>* object,
770 const char* group_section_name,
771 const char* signature,
772 const elfcpp::Shdr<size, big_endian>& shdr,
773 elfcpp::Elf_Word flags,
774 std::vector<unsigned int>* shndxes)
776 gold_assert(parameters->options().relocatable());
777 gold_assert(shdr.get_sh_type() == elfcpp::SHT_GROUP);
778 group_section_name = this->namepool_.add(group_section_name, true, NULL);
779 Output_section* os = this->make_output_section(group_section_name,
782 ORDER_INVALID, false);
784 // We need to find a symbol with the signature in the symbol table.
785 // If we don't find one now, we need to look again later.
786 Symbol* sym = symtab->lookup(signature, NULL);
788 os->set_info_symndx(sym);
791 // Reserve some space to minimize reallocations.
792 if (this->group_signatures_.empty())
793 this->group_signatures_.reserve(this->number_of_input_files_ * 16);
795 // We will wind up using a symbol whose name is the signature.
796 // So just put the signature in the symbol name pool to save it.
797 signature = symtab->canonicalize_name(signature);
798 this->group_signatures_.push_back(Group_signature(os, signature));
801 os->set_should_link_to_symtab();
804 section_size_type entry_count =
805 convert_to_section_size_type(shdr.get_sh_size() / 4);
806 Output_section_data* posd =
807 new Output_data_group<size, big_endian>(object, entry_count, flags,
809 os->add_output_section_data(posd);
812 // Special GNU handling of sections name .eh_frame. They will
813 // normally hold exception frame data as defined by the C++ ABI
814 // (http://codesourcery.com/cxx-abi/).
816 template<int size, bool big_endian>
818 Layout::layout_eh_frame(Sized_relobj<size, big_endian>* object,
819 const unsigned char* symbols,
821 const unsigned char* symbol_names,
822 off_t symbol_names_size,
824 const elfcpp::Shdr<size, big_endian>& shdr,
825 unsigned int reloc_shndx, unsigned int reloc_type,
828 gold_assert(shdr.get_sh_type() == elfcpp::SHT_PROGBITS);
829 gold_assert((shdr.get_sh_flags() & elfcpp::SHF_ALLOC) != 0);
831 const char* const name = ".eh_frame";
832 Output_section* os = this->choose_output_section(object, name,
833 elfcpp::SHT_PROGBITS,
834 elfcpp::SHF_ALLOC, false,
835 ORDER_EHFRAME, false);
839 if (this->eh_frame_section_ == NULL)
841 this->eh_frame_section_ = os;
842 this->eh_frame_data_ = new Eh_frame();
844 if (parameters->options().eh_frame_hdr())
846 Output_section* hdr_os =
847 this->choose_output_section(NULL, ".eh_frame_hdr",
848 elfcpp::SHT_PROGBITS,
849 elfcpp::SHF_ALLOC, false,
850 ORDER_EHFRAME, false);
854 Eh_frame_hdr* hdr_posd = new Eh_frame_hdr(os,
855 this->eh_frame_data_);
856 hdr_os->add_output_section_data(hdr_posd);
858 hdr_os->set_after_input_sections();
860 if (!this->script_options_->saw_phdrs_clause())
862 Output_segment* hdr_oseg;
863 hdr_oseg = this->make_output_segment(elfcpp::PT_GNU_EH_FRAME,
865 hdr_oseg->add_output_section_to_nonload(hdr_os,
869 this->eh_frame_data_->set_eh_frame_hdr(hdr_posd);
874 gold_assert(this->eh_frame_section_ == os);
876 if (this->eh_frame_data_->add_ehframe_input_section(object,
885 os->update_flags_for_input_section(shdr.get_sh_flags());
887 // A writable .eh_frame section is a RELRO section.
888 if ((shdr.get_sh_flags() & elfcpp::SHF_WRITE) != 0)
891 // We found a .eh_frame section we are going to optimize, so now
892 // we can add the set of optimized sections to the output
893 // section. We need to postpone adding this until we've found a
894 // section we can optimize so that the .eh_frame section in
895 // crtbegin.o winds up at the start of the output section.
896 if (!this->added_eh_frame_data_)
898 os->add_output_section_data(this->eh_frame_data_);
899 this->added_eh_frame_data_ = true;
905 // We couldn't handle this .eh_frame section for some reason.
906 // Add it as a normal section.
907 bool saw_sections_clause = this->script_options_->saw_sections_clause();
908 *off = os->add_input_section(this, object, shndx, name, shdr, reloc_shndx,
909 saw_sections_clause);
910 this->have_added_input_section_ = true;
916 // Add POSD to an output section using NAME, TYPE, and FLAGS. Return
917 // the output section.
920 Layout::add_output_section_data(const char* name, elfcpp::Elf_Word type,
921 elfcpp::Elf_Xword flags,
922 Output_section_data* posd,
923 Output_section_order order, bool is_relro)
925 Output_section* os = this->choose_output_section(NULL, name, type, flags,
926 false, order, is_relro);
928 os->add_output_section_data(posd);
932 // Map section flags to segment flags.
935 Layout::section_flags_to_segment(elfcpp::Elf_Xword flags)
937 elfcpp::Elf_Word ret = elfcpp::PF_R;
938 if ((flags & elfcpp::SHF_WRITE) != 0)
940 if ((flags & elfcpp::SHF_EXECINSTR) != 0)
945 // Sometimes we compress sections. This is typically done for
946 // sections that are not part of normal program execution (such as
947 // .debug_* sections), and where the readers of these sections know
948 // how to deal with compressed sections. This routine doesn't say for
949 // certain whether we'll compress -- it depends on commandline options
950 // as well -- just whether this section is a candidate for compression.
951 // (The Output_compressed_section class decides whether to compress
952 // a given section, and picks the name of the compressed section.)
955 is_compressible_debug_section(const char* secname)
957 return (is_prefix_of(".debug", secname));
960 // We may see compressed debug sections in input files. Return TRUE
961 // if this is the name of a compressed debug section.
964 is_compressed_debug_section(const char* secname)
966 return (is_prefix_of(".zdebug", secname));
969 // Make a new Output_section, and attach it to segments as
970 // appropriate. ORDER is the order in which this section should
971 // appear in the output segment. IS_RELRO is true if this is a relro
972 // (read-only after relocations) section.
975 Layout::make_output_section(const char* name, elfcpp::Elf_Word type,
976 elfcpp::Elf_Xword flags,
977 Output_section_order order, bool is_relro)
980 if ((flags & elfcpp::SHF_ALLOC) == 0
981 && strcmp(parameters->options().compress_debug_sections(), "none") != 0
982 && is_compressible_debug_section(name))
983 os = new Output_compressed_section(¶meters->options(), name, type,
985 else if ((flags & elfcpp::SHF_ALLOC) == 0
986 && parameters->options().strip_debug_non_line()
987 && strcmp(".debug_abbrev", name) == 0)
989 os = this->debug_abbrev_ = new Output_reduced_debug_abbrev_section(
991 if (this->debug_info_)
992 this->debug_info_->set_abbreviations(this->debug_abbrev_);
994 else if ((flags & elfcpp::SHF_ALLOC) == 0
995 && parameters->options().strip_debug_non_line()
996 && strcmp(".debug_info", name) == 0)
998 os = this->debug_info_ = new Output_reduced_debug_info_section(
1000 if (this->debug_abbrev_)
1001 this->debug_info_->set_abbreviations(this->debug_abbrev_);
1005 // FIXME: const_cast is ugly.
1006 Target* target = const_cast<Target*>(¶meters->target());
1007 os = target->make_output_section(name, type, flags);
1010 // With -z relro, we have to recognize the special sections by name.
1011 // There is no other way.
1012 bool is_relro_local = false;
1013 if (!this->script_options_->saw_sections_clause()
1014 && parameters->options().relro()
1015 && type == elfcpp::SHT_PROGBITS
1016 && (flags & elfcpp::SHF_ALLOC) != 0
1017 && (flags & elfcpp::SHF_WRITE) != 0)
1019 if (strcmp(name, ".data.rel.ro") == 0)
1021 else if (strcmp(name, ".data.rel.ro.local") == 0)
1024 is_relro_local = true;
1026 else if (type == elfcpp::SHT_INIT_ARRAY
1027 || type == elfcpp::SHT_FINI_ARRAY
1028 || type == elfcpp::SHT_PREINIT_ARRAY)
1030 else if (strcmp(name, ".ctors") == 0
1031 || strcmp(name, ".dtors") == 0
1032 || strcmp(name, ".jcr") == 0)
1039 if (order == ORDER_INVALID && (flags & elfcpp::SHF_ALLOC) != 0)
1040 order = this->default_section_order(os, is_relro_local);
1042 os->set_order(order);
1044 parameters->target().new_output_section(os);
1046 this->section_list_.push_back(os);
1048 // The GNU linker by default sorts some sections by priority, so we
1049 // do the same. We need to know that this might happen before we
1050 // attach any input sections.
1051 if (!this->script_options_->saw_sections_clause()
1052 && (strcmp(name, ".ctors") == 0
1053 || strcmp(name, ".dtors") == 0
1054 || strcmp(name, ".init_array") == 0
1055 || strcmp(name, ".fini_array") == 0))
1056 os->set_may_sort_attached_input_sections();
1058 // Check for .stab*str sections, as .stab* sections need to link to
1060 if (type == elfcpp::SHT_STRTAB
1061 && !this->have_stabstr_section_
1062 && strncmp(name, ".stab", 5) == 0
1063 && strcmp(name + strlen(name) - 3, "str") == 0)
1064 this->have_stabstr_section_ = true;
1066 // If we have already attached the sections to segments, then we
1067 // need to attach this one now. This happens for sections created
1068 // directly by the linker.
1069 if (this->sections_are_attached_)
1070 this->attach_section_to_segment(os);
1075 // Return the default order in which a section should be placed in an
1076 // output segment. This function captures a lot of the ideas in
1077 // ld/scripttempl/elf.sc in the GNU linker. Note that the order of a
1078 // linker created section is normally set when the section is created;
1079 // this function is used for input sections.
1081 Output_section_order
1082 Layout::default_section_order(Output_section* os, bool is_relro_local)
1084 gold_assert((os->flags() & elfcpp::SHF_ALLOC) != 0);
1085 bool is_write = (os->flags() & elfcpp::SHF_WRITE) != 0;
1086 bool is_execinstr = (os->flags() & elfcpp::SHF_EXECINSTR) != 0;
1087 bool is_bss = false;
1092 case elfcpp::SHT_PROGBITS:
1094 case elfcpp::SHT_NOBITS:
1097 case elfcpp::SHT_RELA:
1098 case elfcpp::SHT_REL:
1100 return ORDER_DYNAMIC_RELOCS;
1102 case elfcpp::SHT_HASH:
1103 case elfcpp::SHT_DYNAMIC:
1104 case elfcpp::SHT_SHLIB:
1105 case elfcpp::SHT_DYNSYM:
1106 case elfcpp::SHT_GNU_HASH:
1107 case elfcpp::SHT_GNU_verdef:
1108 case elfcpp::SHT_GNU_verneed:
1109 case elfcpp::SHT_GNU_versym:
1111 return ORDER_DYNAMIC_LINKER;
1113 case elfcpp::SHT_NOTE:
1114 return is_write ? ORDER_RW_NOTE : ORDER_RO_NOTE;
1117 if ((os->flags() & elfcpp::SHF_TLS) != 0)
1118 return is_bss ? ORDER_TLS_BSS : ORDER_TLS_DATA;
1120 if (!is_bss && !is_write)
1124 if (strcmp(os->name(), ".init") == 0)
1126 else if (strcmp(os->name(), ".fini") == 0)
1129 return is_execinstr ? ORDER_TEXT : ORDER_READONLY;
1133 return is_relro_local ? ORDER_RELRO_LOCAL : ORDER_RELRO;
1135 if (os->is_small_section())
1136 return is_bss ? ORDER_SMALL_BSS : ORDER_SMALL_DATA;
1137 if (os->is_large_section())
1138 return is_bss ? ORDER_LARGE_BSS : ORDER_LARGE_DATA;
1140 return is_bss ? ORDER_BSS : ORDER_DATA;
1143 // Attach output sections to segments. This is called after we have
1144 // seen all the input sections.
1147 Layout::attach_sections_to_segments()
1149 for (Section_list::iterator p = this->section_list_.begin();
1150 p != this->section_list_.end();
1152 this->attach_section_to_segment(*p);
1154 this->sections_are_attached_ = true;
1157 // Attach an output section to a segment.
1160 Layout::attach_section_to_segment(Output_section* os)
1162 if ((os->flags() & elfcpp::SHF_ALLOC) == 0)
1163 this->unattached_section_list_.push_back(os);
1165 this->attach_allocated_section_to_segment(os);
1168 // Attach an allocated output section to a segment.
1171 Layout::attach_allocated_section_to_segment(Output_section* os)
1173 elfcpp::Elf_Xword flags = os->flags();
1174 gold_assert((flags & elfcpp::SHF_ALLOC) != 0);
1176 if (parameters->options().relocatable())
1179 // If we have a SECTIONS clause, we can't handle the attachment to
1180 // segments until after we've seen all the sections.
1181 if (this->script_options_->saw_sections_clause())
1184 gold_assert(!this->script_options_->saw_phdrs_clause());
1186 // This output section goes into a PT_LOAD segment.
1188 elfcpp::Elf_Word seg_flags = Layout::section_flags_to_segment(flags);
1190 // Check for --section-start.
1192 bool is_address_set = parameters->options().section_start(os->name(), &addr);
1194 // In general the only thing we really care about for PT_LOAD
1195 // segments is whether or not they are writable or executable,
1196 // so that is how we search for them.
1197 // Large data sections also go into their own PT_LOAD segment.
1198 // People who need segments sorted on some other basis will
1199 // have to use a linker script.
1201 Segment_list::const_iterator p;
1202 for (p = this->segment_list_.begin();
1203 p != this->segment_list_.end();
1206 if ((*p)->type() != elfcpp::PT_LOAD)
1208 if (!parameters->options().omagic()
1209 && ((*p)->flags() & elfcpp::PF_W) != (seg_flags & elfcpp::PF_W))
1211 if (parameters->options().rosegment()
1212 && ((*p)->flags() & elfcpp::PF_X) != (seg_flags & elfcpp::PF_X))
1214 // If -Tbss was specified, we need to separate the data and BSS
1216 if (parameters->options().user_set_Tbss())
1218 if ((os->type() == elfcpp::SHT_NOBITS)
1219 == (*p)->has_any_data_sections())
1222 if (os->is_large_data_section() && !(*p)->is_large_data_segment())
1227 if ((*p)->are_addresses_set())
1230 (*p)->add_initial_output_data(os);
1231 (*p)->update_flags_for_output_section(seg_flags);
1232 (*p)->set_addresses(addr, addr);
1236 (*p)->add_output_section_to_load(this, os, seg_flags);
1240 if (p == this->segment_list_.end())
1242 Output_segment* oseg = this->make_output_segment(elfcpp::PT_LOAD,
1244 if (os->is_large_data_section())
1245 oseg->set_is_large_data_segment();
1246 oseg->add_output_section_to_load(this, os, seg_flags);
1248 oseg->set_addresses(addr, addr);
1251 // If we see a loadable SHT_NOTE section, we create a PT_NOTE
1253 if (os->type() == elfcpp::SHT_NOTE)
1255 // See if we already have an equivalent PT_NOTE segment.
1256 for (p = this->segment_list_.begin();
1257 p != segment_list_.end();
1260 if ((*p)->type() == elfcpp::PT_NOTE
1261 && (((*p)->flags() & elfcpp::PF_W)
1262 == (seg_flags & elfcpp::PF_W)))
1264 (*p)->add_output_section_to_nonload(os, seg_flags);
1269 if (p == this->segment_list_.end())
1271 Output_segment* oseg = this->make_output_segment(elfcpp::PT_NOTE,
1273 oseg->add_output_section_to_nonload(os, seg_flags);
1277 // If we see a loadable SHF_TLS section, we create a PT_TLS
1278 // segment. There can only be one such segment.
1279 if ((flags & elfcpp::SHF_TLS) != 0)
1281 if (this->tls_segment_ == NULL)
1282 this->make_output_segment(elfcpp::PT_TLS, seg_flags);
1283 this->tls_segment_->add_output_section_to_nonload(os, seg_flags);
1286 // If -z relro is in effect, and we see a relro section, we create a
1287 // PT_GNU_RELRO segment. There can only be one such segment.
1288 if (os->is_relro() && parameters->options().relro())
1290 gold_assert(seg_flags == (elfcpp::PF_R | elfcpp::PF_W));
1291 if (this->relro_segment_ == NULL)
1292 this->make_output_segment(elfcpp::PT_GNU_RELRO, seg_flags);
1293 this->relro_segment_->add_output_section_to_nonload(os, seg_flags);
1297 // Make an output section for a script.
1300 Layout::make_output_section_for_script(
1302 Script_sections::Section_type section_type)
1304 name = this->namepool_.add(name, false, NULL);
1305 elfcpp::Elf_Xword sh_flags = elfcpp::SHF_ALLOC;
1306 if (section_type == Script_sections::ST_NOLOAD)
1308 Output_section* os = this->make_output_section(name, elfcpp::SHT_PROGBITS,
1309 sh_flags, ORDER_INVALID,
1311 os->set_found_in_sections_clause();
1312 if (section_type == Script_sections::ST_NOLOAD)
1313 os->set_is_noload();
1317 // Return the number of segments we expect to see.
1320 Layout::expected_segment_count() const
1322 size_t ret = this->segment_list_.size();
1324 // If we didn't see a SECTIONS clause in a linker script, we should
1325 // already have the complete list of segments. Otherwise we ask the
1326 // SECTIONS clause how many segments it expects, and add in the ones
1327 // we already have (PT_GNU_STACK, PT_GNU_EH_FRAME, etc.)
1329 if (!this->script_options_->saw_sections_clause())
1333 const Script_sections* ss = this->script_options_->script_sections();
1334 return ret + ss->expected_segment_count(this);
1338 // Handle the .note.GNU-stack section at layout time. SEEN_GNU_STACK
1339 // is whether we saw a .note.GNU-stack section in the object file.
1340 // GNU_STACK_FLAGS is the section flags. The flags give the
1341 // protection required for stack memory. We record this in an
1342 // executable as a PT_GNU_STACK segment. If an object file does not
1343 // have a .note.GNU-stack segment, we must assume that it is an old
1344 // object. On some targets that will force an executable stack.
1347 Layout::layout_gnu_stack(bool seen_gnu_stack, uint64_t gnu_stack_flags)
1349 if (!seen_gnu_stack)
1350 this->input_without_gnu_stack_note_ = true;
1353 this->input_with_gnu_stack_note_ = true;
1354 if ((gnu_stack_flags & elfcpp::SHF_EXECINSTR) != 0)
1355 this->input_requires_executable_stack_ = true;
1359 // Create automatic note sections.
1362 Layout::create_notes()
1364 this->create_gold_note();
1365 this->create_executable_stack_info();
1366 this->create_build_id();
1369 // Create the dynamic sections which are needed before we read the
1373 Layout::create_initial_dynamic_sections(Symbol_table* symtab)
1375 if (parameters->doing_static_link())
1378 this->dynamic_section_ = this->choose_output_section(NULL, ".dynamic",
1379 elfcpp::SHT_DYNAMIC,
1381 | elfcpp::SHF_WRITE),
1385 this->dynamic_symbol_ =
1386 symtab->define_in_output_data("_DYNAMIC", NULL, Symbol_table::PREDEFINED,
1387 this->dynamic_section_, 0, 0,
1388 elfcpp::STT_OBJECT, elfcpp::STB_LOCAL,
1389 elfcpp::STV_HIDDEN, 0, false, false);
1391 this->dynamic_data_ = new Output_data_dynamic(&this->dynpool_);
1393 this->dynamic_section_->add_output_section_data(this->dynamic_data_);
1396 // For each output section whose name can be represented as C symbol,
1397 // define __start and __stop symbols for the section. This is a GNU
1401 Layout::define_section_symbols(Symbol_table* symtab)
1403 for (Section_list::const_iterator p = this->section_list_.begin();
1404 p != this->section_list_.end();
1407 const char* const name = (*p)->name();
1408 if (is_cident(name))
1410 const std::string name_string(name);
1411 const std::string start_name(cident_section_start_prefix
1413 const std::string stop_name(cident_section_stop_prefix
1416 symtab->define_in_output_data(start_name.c_str(),
1418 Symbol_table::PREDEFINED,
1424 elfcpp::STV_DEFAULT,
1426 false, // offset_is_from_end
1427 true); // only_if_ref
1429 symtab->define_in_output_data(stop_name.c_str(),
1431 Symbol_table::PREDEFINED,
1437 elfcpp::STV_DEFAULT,
1439 true, // offset_is_from_end
1440 true); // only_if_ref
1445 // Define symbols for group signatures.
1448 Layout::define_group_signatures(Symbol_table* symtab)
1450 for (Group_signatures::iterator p = this->group_signatures_.begin();
1451 p != this->group_signatures_.end();
1454 Symbol* sym = symtab->lookup(p->signature, NULL);
1456 p->section->set_info_symndx(sym);
1459 // Force the name of the group section to the group
1460 // signature, and use the group's section symbol as the
1461 // signature symbol.
1462 if (strcmp(p->section->name(), p->signature) != 0)
1464 const char* name = this->namepool_.add(p->signature,
1466 p->section->set_name(name);
1468 p->section->set_needs_symtab_index();
1469 p->section->set_info_section_symndx(p->section);
1473 this->group_signatures_.clear();
1476 // Find the first read-only PT_LOAD segment, creating one if
1480 Layout::find_first_load_seg()
1482 Output_segment* best = NULL;
1483 for (Segment_list::const_iterator p = this->segment_list_.begin();
1484 p != this->segment_list_.end();
1487 if ((*p)->type() == elfcpp::PT_LOAD
1488 && ((*p)->flags() & elfcpp::PF_R) != 0
1489 && (parameters->options().omagic()
1490 || ((*p)->flags() & elfcpp::PF_W) == 0))
1492 if (best == NULL || this->segment_precedes(*p, best))
1499 gold_assert(!this->script_options_->saw_phdrs_clause());
1501 Output_segment* load_seg = this->make_output_segment(elfcpp::PT_LOAD,
1506 // Save states of all current output segments. Store saved states
1507 // in SEGMENT_STATES.
1510 Layout::save_segments(Segment_states* segment_states)
1512 for (Segment_list::const_iterator p = this->segment_list_.begin();
1513 p != this->segment_list_.end();
1516 Output_segment* segment = *p;
1518 Output_segment* copy = new Output_segment(*segment);
1519 (*segment_states)[segment] = copy;
1523 // Restore states of output segments and delete any segment not found in
1527 Layout::restore_segments(const Segment_states* segment_states)
1529 // Go through the segment list and remove any segment added in the
1531 this->tls_segment_ = NULL;
1532 this->relro_segment_ = NULL;
1533 Segment_list::iterator list_iter = this->segment_list_.begin();
1534 while (list_iter != this->segment_list_.end())
1536 Output_segment* segment = *list_iter;
1537 Segment_states::const_iterator states_iter =
1538 segment_states->find(segment);
1539 if (states_iter != segment_states->end())
1541 const Output_segment* copy = states_iter->second;
1542 // Shallow copy to restore states.
1545 // Also fix up TLS and RELRO segment pointers as appropriate.
1546 if (segment->type() == elfcpp::PT_TLS)
1547 this->tls_segment_ = segment;
1548 else if (segment->type() == elfcpp::PT_GNU_RELRO)
1549 this->relro_segment_ = segment;
1555 list_iter = this->segment_list_.erase(list_iter);
1556 // This is a segment created during section layout. It should be
1557 // safe to remove it since we should have removed all pointers to it.
1563 // Clean up after relaxation so that sections can be laid out again.
1566 Layout::clean_up_after_relaxation()
1568 // Restore the segments to point state just prior to the relaxation loop.
1569 Script_sections* script_section = this->script_options_->script_sections();
1570 script_section->release_segments();
1571 this->restore_segments(this->segment_states_);
1573 // Reset section addresses and file offsets
1574 for (Section_list::iterator p = this->section_list_.begin();
1575 p != this->section_list_.end();
1578 (*p)->restore_states();
1580 // If an input section changes size because of relaxation,
1581 // we need to adjust the section offsets of all input sections.
1582 // after such a section.
1583 if ((*p)->section_offsets_need_adjustment())
1584 (*p)->adjust_section_offsets();
1586 (*p)->reset_address_and_file_offset();
1589 // Reset special output object address and file offsets.
1590 for (Data_list::iterator p = this->special_output_list_.begin();
1591 p != this->special_output_list_.end();
1593 (*p)->reset_address_and_file_offset();
1595 // A linker script may have created some output section data objects.
1596 // They are useless now.
1597 for (Output_section_data_list::const_iterator p =
1598 this->script_output_section_data_list_.begin();
1599 p != this->script_output_section_data_list_.end();
1602 this->script_output_section_data_list_.clear();
1605 // Prepare for relaxation.
1608 Layout::prepare_for_relaxation()
1610 // Create an relaxation debug check if in debugging mode.
1611 if (is_debugging_enabled(DEBUG_RELAXATION))
1612 this->relaxation_debug_check_ = new Relaxation_debug_check();
1614 // Save segment states.
1615 this->segment_states_ = new Segment_states();
1616 this->save_segments(this->segment_states_);
1618 for(Section_list::const_iterator p = this->section_list_.begin();
1619 p != this->section_list_.end();
1621 (*p)->save_states();
1623 if (is_debugging_enabled(DEBUG_RELAXATION))
1624 this->relaxation_debug_check_->check_output_data_for_reset_values(
1625 this->section_list_, this->special_output_list_);
1627 // Also enable recording of output section data from scripts.
1628 this->record_output_section_data_from_script_ = true;
1631 // Relaxation loop body: If target has no relaxation, this runs only once
1632 // Otherwise, the target relaxation hook is called at the end of
1633 // each iteration. If the hook returns true, it means re-layout of
1634 // section is required.
1636 // The number of segments created by a linking script without a PHDRS
1637 // clause may be affected by section sizes and alignments. There is
1638 // a remote chance that relaxation causes different number of PT_LOAD
1639 // segments are created and sections are attached to different segments.
1640 // Therefore, we always throw away all segments created during section
1641 // layout. In order to be able to restart the section layout, we keep
1642 // a copy of the segment list right before the relaxation loop and use
1643 // that to restore the segments.
1645 // PASS is the current relaxation pass number.
1646 // SYMTAB is a symbol table.
1647 // PLOAD_SEG is the address of a pointer for the load segment.
1648 // PHDR_SEG is a pointer to the PHDR segment.
1649 // SEGMENT_HEADERS points to the output segment header.
1650 // FILE_HEADER points to the output file header.
1651 // PSHNDX is the address to store the output section index.
1654 Layout::relaxation_loop_body(
1657 Symbol_table* symtab,
1658 Output_segment** pload_seg,
1659 Output_segment* phdr_seg,
1660 Output_segment_headers* segment_headers,
1661 Output_file_header* file_header,
1662 unsigned int* pshndx)
1664 // If this is not the first iteration, we need to clean up after
1665 // relaxation so that we can lay out the sections again.
1667 this->clean_up_after_relaxation();
1669 // If there is a SECTIONS clause, put all the input sections into
1670 // the required order.
1671 Output_segment* load_seg;
1672 if (this->script_options_->saw_sections_clause())
1673 load_seg = this->set_section_addresses_from_script(symtab);
1674 else if (parameters->options().relocatable())
1677 load_seg = this->find_first_load_seg();
1679 if (parameters->options().oformat_enum()
1680 != General_options::OBJECT_FORMAT_ELF)
1683 // If the user set the address of the text segment, that may not be
1684 // compatible with putting the segment headers and file headers into
1686 if (parameters->options().user_set_Ttext())
1689 gold_assert(phdr_seg == NULL
1691 || this->script_options_->saw_sections_clause());
1693 // If the address of the load segment we found has been set by
1694 // --section-start rather than by a script, then adjust the VMA and
1695 // LMA downward if possible to include the file and section headers.
1696 uint64_t header_gap = 0;
1697 if (load_seg != NULL
1698 && load_seg->are_addresses_set()
1699 && !this->script_options_->saw_sections_clause()
1700 && !parameters->options().relocatable())
1702 file_header->finalize_data_size();
1703 segment_headers->finalize_data_size();
1704 size_t sizeof_headers = (file_header->data_size()
1705 + segment_headers->data_size());
1706 const uint64_t abi_pagesize = target->abi_pagesize();
1707 uint64_t hdr_paddr = load_seg->paddr() - sizeof_headers;
1708 hdr_paddr &= ~(abi_pagesize - 1);
1709 uint64_t subtract = load_seg->paddr() - hdr_paddr;
1710 if (load_seg->paddr() < subtract || load_seg->vaddr() < subtract)
1714 load_seg->set_addresses(load_seg->vaddr() - subtract,
1715 load_seg->paddr() - subtract);
1716 header_gap = subtract - sizeof_headers;
1720 // Lay out the segment headers.
1721 if (!parameters->options().relocatable())
1723 gold_assert(segment_headers != NULL);
1724 if (header_gap != 0 && load_seg != NULL)
1726 Output_data_zero_fill* z = new Output_data_zero_fill(header_gap, 1);
1727 load_seg->add_initial_output_data(z);
1729 if (load_seg != NULL)
1730 load_seg->add_initial_output_data(segment_headers);
1731 if (phdr_seg != NULL)
1732 phdr_seg->add_initial_output_data(segment_headers);
1735 // Lay out the file header.
1736 if (load_seg != NULL)
1737 load_seg->add_initial_output_data(file_header);
1739 if (this->script_options_->saw_phdrs_clause()
1740 && !parameters->options().relocatable())
1742 // Support use of FILEHDRS and PHDRS attachments in a PHDRS
1743 // clause in a linker script.
1744 Script_sections* ss = this->script_options_->script_sections();
1745 ss->put_headers_in_phdrs(file_header, segment_headers);
1748 // We set the output section indexes in set_segment_offsets and
1749 // set_section_indexes.
1752 // Set the file offsets of all the segments, and all the sections
1755 if (!parameters->options().relocatable())
1756 off = this->set_segment_offsets(target, load_seg, pshndx);
1758 off = this->set_relocatable_section_offsets(file_header, pshndx);
1760 // Verify that the dummy relaxation does not change anything.
1761 if (is_debugging_enabled(DEBUG_RELAXATION))
1764 this->relaxation_debug_check_->read_sections(this->section_list_);
1766 this->relaxation_debug_check_->verify_sections(this->section_list_);
1769 *pload_seg = load_seg;
1773 // Search the list of patterns and find the postion of the given section
1774 // name in the output section. If the section name matches a glob
1775 // pattern and a non-glob name, then the non-glob position takes
1776 // precedence. Return 0 if no match is found.
1779 Layout::find_section_order_index(const std::string& section_name)
1781 Unordered_map<std::string, unsigned int>::iterator map_it;
1782 map_it = this->input_section_position_.find(section_name);
1783 if (map_it != this->input_section_position_.end())
1784 return map_it->second;
1786 // Absolute match failed. Linear search the glob patterns.
1787 std::vector<std::string>::iterator it;
1788 for (it = this->input_section_glob_.begin();
1789 it != this->input_section_glob_.end();
1792 if (fnmatch((*it).c_str(), section_name.c_str(), FNM_NOESCAPE) == 0)
1794 map_it = this->input_section_position_.find(*it);
1795 gold_assert(map_it != this->input_section_position_.end());
1796 return map_it->second;
1802 // Read the sequence of input sections from the file specified with
1803 // --section-ordering-file.
1806 Layout::read_layout_from_file()
1808 const char* filename = parameters->options().section_ordering_file();
1814 gold_fatal(_("unable to open --section-ordering-file file %s: %s"),
1815 filename, strerror(errno));
1817 std::getline(in, line); // this chops off the trailing \n, if any
1818 unsigned int position = 1;
1822 if (!line.empty() && line[line.length() - 1] == '\r') // Windows
1823 line.resize(line.length() - 1);
1824 // Ignore comments, beginning with '#'
1827 std::getline(in, line);
1830 this->input_section_position_[line] = position;
1831 // Store all glob patterns in a vector.
1832 if (is_wildcard_string(line.c_str()))
1833 this->input_section_glob_.push_back(line);
1835 std::getline(in, line);
1839 // Finalize the layout. When this is called, we have created all the
1840 // output sections and all the output segments which are based on
1841 // input sections. We have several things to do, and we have to do
1842 // them in the right order, so that we get the right results correctly
1845 // 1) Finalize the list of output segments and create the segment
1848 // 2) Finalize the dynamic symbol table and associated sections.
1850 // 3) Determine the final file offset of all the output segments.
1852 // 4) Determine the final file offset of all the SHF_ALLOC output
1855 // 5) Create the symbol table sections and the section name table
1858 // 6) Finalize the symbol table: set symbol values to their final
1859 // value and make a final determination of which symbols are going
1860 // into the output symbol table.
1862 // 7) Create the section table header.
1864 // 8) Determine the final file offset of all the output sections which
1865 // are not SHF_ALLOC, including the section table header.
1867 // 9) Finalize the ELF file header.
1869 // This function returns the size of the output file.
1872 Layout::finalize(const Input_objects* input_objects, Symbol_table* symtab,
1873 Target* target, const Task* task)
1875 target->finalize_sections(this, input_objects, symtab);
1877 this->count_local_symbols(task, input_objects);
1879 this->link_stabs_sections();
1881 Output_segment* phdr_seg = NULL;
1882 if (!parameters->options().relocatable() && !parameters->doing_static_link())
1884 // There was a dynamic object in the link. We need to create
1885 // some information for the dynamic linker.
1887 // Create the PT_PHDR segment which will hold the program
1889 if (!this->script_options_->saw_phdrs_clause())
1890 phdr_seg = this->make_output_segment(elfcpp::PT_PHDR, elfcpp::PF_R);
1892 // Create the dynamic symbol table, including the hash table.
1893 Output_section* dynstr;
1894 std::vector<Symbol*> dynamic_symbols;
1895 unsigned int local_dynamic_count;
1896 Versions versions(*this->script_options()->version_script_info(),
1898 this->create_dynamic_symtab(input_objects, symtab, &dynstr,
1899 &local_dynamic_count, &dynamic_symbols,
1902 // Create the .interp section to hold the name of the
1903 // interpreter, and put it in a PT_INTERP segment.
1904 if (!parameters->options().shared())
1905 this->create_interp(target);
1907 // Finish the .dynamic section to hold the dynamic data, and put
1908 // it in a PT_DYNAMIC segment.
1909 this->finish_dynamic_section(input_objects, symtab);
1911 // We should have added everything we need to the dynamic string
1913 this->dynpool_.set_string_offsets();
1915 // Create the version sections. We can't do this until the
1916 // dynamic string table is complete.
1917 this->create_version_sections(&versions, symtab, local_dynamic_count,
1918 dynamic_symbols, dynstr);
1920 // Set the size of the _DYNAMIC symbol. We can't do this until
1921 // after we call create_version_sections.
1922 this->set_dynamic_symbol_size(symtab);
1925 // Create segment headers.
1926 Output_segment_headers* segment_headers =
1927 (parameters->options().relocatable()
1929 : new Output_segment_headers(this->segment_list_));
1931 // Lay out the file header.
1932 Output_file_header* file_header
1933 = new Output_file_header(target, symtab, segment_headers,
1934 parameters->options().entry());
1936 this->special_output_list_.push_back(file_header);
1937 if (segment_headers != NULL)
1938 this->special_output_list_.push_back(segment_headers);
1940 // Find approriate places for orphan output sections if we are using
1942 if (this->script_options_->saw_sections_clause())
1943 this->place_orphan_sections_in_script();
1945 Output_segment* load_seg;
1950 // Take a snapshot of the section layout as needed.
1951 if (target->may_relax())
1952 this->prepare_for_relaxation();
1954 // Run the relaxation loop to lay out sections.
1957 off = this->relaxation_loop_body(pass, target, symtab, &load_seg,
1958 phdr_seg, segment_headers, file_header,
1962 while (target->may_relax()
1963 && target->relax(pass, input_objects, symtab, this));
1965 // Set the file offsets of all the non-data sections we've seen so
1966 // far which don't have to wait for the input sections. We need
1967 // this in order to finalize local symbols in non-allocated
1969 off = this->set_section_offsets(off, BEFORE_INPUT_SECTIONS_PASS);
1971 // Set the section indexes of all unallocated sections seen so far,
1972 // in case any of them are somehow referenced by a symbol.
1973 shndx = this->set_section_indexes(shndx);
1975 // Create the symbol table sections.
1976 this->create_symtab_sections(input_objects, symtab, shndx, &off);
1977 if (!parameters->doing_static_link())
1978 this->assign_local_dynsym_offsets(input_objects);
1980 // Process any symbol assignments from a linker script. This must
1981 // be called after the symbol table has been finalized.
1982 this->script_options_->finalize_symbols(symtab, this);
1984 // Create the incremental inputs sections.
1985 if (this->incremental_inputs_)
1987 this->incremental_inputs_->finalize();
1988 this->create_incremental_info_sections(symtab);
1991 // Create the .shstrtab section.
1992 Output_section* shstrtab_section = this->create_shstrtab();
1994 // Set the file offsets of the rest of the non-data sections which
1995 // don't have to wait for the input sections.
1996 off = this->set_section_offsets(off, BEFORE_INPUT_SECTIONS_PASS);
1998 // Now that all sections have been created, set the section indexes
1999 // for any sections which haven't been done yet.
2000 shndx = this->set_section_indexes(shndx);
2002 // Create the section table header.
2003 this->create_shdrs(shstrtab_section, &off);
2005 // If there are no sections which require postprocessing, we can
2006 // handle the section names now, and avoid a resize later.
2007 if (!this->any_postprocessing_sections_)
2009 off = this->set_section_offsets(off,
2010 POSTPROCESSING_SECTIONS_PASS);
2012 this->set_section_offsets(off,
2013 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS);
2016 file_header->set_section_info(this->section_headers_, shstrtab_section);
2018 // Now we know exactly where everything goes in the output file
2019 // (except for non-allocated sections which require postprocessing).
2020 Output_data::layout_complete();
2022 this->output_file_size_ = off;
2027 // Create a note header following the format defined in the ELF ABI.
2028 // NAME is the name, NOTE_TYPE is the type, SECTION_NAME is the name
2029 // of the section to create, DESCSZ is the size of the descriptor.
2030 // ALLOCATE is true if the section should be allocated in memory.
2031 // This returns the new note section. It sets *TRAILING_PADDING to
2032 // the number of trailing zero bytes required.
2035 Layout::create_note(const char* name, int note_type,
2036 const char* section_name, size_t descsz,
2037 bool allocate, size_t* trailing_padding)
2039 // Authorities all agree that the values in a .note field should
2040 // be aligned on 4-byte boundaries for 32-bit binaries. However,
2041 // they differ on what the alignment is for 64-bit binaries.
2042 // The GABI says unambiguously they take 8-byte alignment:
2043 // http://sco.com/developers/gabi/latest/ch5.pheader.html#note_section
2044 // Other documentation says alignment should always be 4 bytes:
2045 // http://www.netbsd.org/docs/kernel/elf-notes.html#note-format
2046 // GNU ld and GNU readelf both support the latter (at least as of
2047 // version 2.16.91), and glibc always generates the latter for
2048 // .note.ABI-tag (as of version 1.6), so that's the one we go with
2050 #ifdef GABI_FORMAT_FOR_DOTNOTE_SECTION // This is not defined by default.
2051 const int size = parameters->target().get_size();
2053 const int size = 32;
2056 // The contents of the .note section.
2057 size_t namesz = strlen(name) + 1;
2058 size_t aligned_namesz = align_address(namesz, size / 8);
2059 size_t aligned_descsz = align_address(descsz, size / 8);
2061 size_t notehdrsz = 3 * (size / 8) + aligned_namesz;
2063 unsigned char* buffer = new unsigned char[notehdrsz];
2064 memset(buffer, 0, notehdrsz);
2066 bool is_big_endian = parameters->target().is_big_endian();
2072 elfcpp::Swap<32, false>::writeval(buffer, namesz);
2073 elfcpp::Swap<32, false>::writeval(buffer + 4, descsz);
2074 elfcpp::Swap<32, false>::writeval(buffer + 8, note_type);
2078 elfcpp::Swap<32, true>::writeval(buffer, namesz);
2079 elfcpp::Swap<32, true>::writeval(buffer + 4, descsz);
2080 elfcpp::Swap<32, true>::writeval(buffer + 8, note_type);
2083 else if (size == 64)
2087 elfcpp::Swap<64, false>::writeval(buffer, namesz);
2088 elfcpp::Swap<64, false>::writeval(buffer + 8, descsz);
2089 elfcpp::Swap<64, false>::writeval(buffer + 16, note_type);
2093 elfcpp::Swap<64, true>::writeval(buffer, namesz);
2094 elfcpp::Swap<64, true>::writeval(buffer + 8, descsz);
2095 elfcpp::Swap<64, true>::writeval(buffer + 16, note_type);
2101 memcpy(buffer + 3 * (size / 8), name, namesz);
2103 elfcpp::Elf_Xword flags = 0;
2104 Output_section_order order = ORDER_INVALID;
2107 flags = elfcpp::SHF_ALLOC;
2108 order = ORDER_RO_NOTE;
2110 Output_section* os = this->choose_output_section(NULL, section_name,
2112 flags, false, order, false);
2116 Output_section_data* posd = new Output_data_const_buffer(buffer, notehdrsz,
2119 os->add_output_section_data(posd);
2121 *trailing_padding = aligned_descsz - descsz;
2126 // For an executable or shared library, create a note to record the
2127 // version of gold used to create the binary.
2130 Layout::create_gold_note()
2132 if (parameters->options().relocatable())
2135 std::string desc = std::string("gold ") + gold::get_version_string();
2137 size_t trailing_padding;
2138 Output_section* os = this->create_note("GNU", elfcpp::NT_GNU_GOLD_VERSION,
2139 ".note.gnu.gold-version", desc.size(),
2140 false, &trailing_padding);
2144 Output_section_data* posd = new Output_data_const(desc, 4);
2145 os->add_output_section_data(posd);
2147 if (trailing_padding > 0)
2149 posd = new Output_data_zero_fill(trailing_padding, 0);
2150 os->add_output_section_data(posd);
2154 // Record whether the stack should be executable. This can be set
2155 // from the command line using the -z execstack or -z noexecstack
2156 // options. Otherwise, if any input file has a .note.GNU-stack
2157 // section with the SHF_EXECINSTR flag set, the stack should be
2158 // executable. Otherwise, if at least one input file a
2159 // .note.GNU-stack section, and some input file has no .note.GNU-stack
2160 // section, we use the target default for whether the stack should be
2161 // executable. Otherwise, we don't generate a stack note. When
2162 // generating a object file, we create a .note.GNU-stack section with
2163 // the appropriate marking. When generating an executable or shared
2164 // library, we create a PT_GNU_STACK segment.
2167 Layout::create_executable_stack_info()
2169 bool is_stack_executable;
2170 if (parameters->options().is_execstack_set())
2171 is_stack_executable = parameters->options().is_stack_executable();
2172 else if (!this->input_with_gnu_stack_note_)
2176 if (this->input_requires_executable_stack_)
2177 is_stack_executable = true;
2178 else if (this->input_without_gnu_stack_note_)
2179 is_stack_executable =
2180 parameters->target().is_default_stack_executable();
2182 is_stack_executable = false;
2185 if (parameters->options().relocatable())
2187 const char* name = this->namepool_.add(".note.GNU-stack", false, NULL);
2188 elfcpp::Elf_Xword flags = 0;
2189 if (is_stack_executable)
2190 flags |= elfcpp::SHF_EXECINSTR;
2191 this->make_output_section(name, elfcpp::SHT_PROGBITS, flags,
2192 ORDER_INVALID, false);
2196 if (this->script_options_->saw_phdrs_clause())
2198 int flags = elfcpp::PF_R | elfcpp::PF_W;
2199 if (is_stack_executable)
2200 flags |= elfcpp::PF_X;
2201 this->make_output_segment(elfcpp::PT_GNU_STACK, flags);
2205 // If --build-id was used, set up the build ID note.
2208 Layout::create_build_id()
2210 if (!parameters->options().user_set_build_id())
2213 const char* style = parameters->options().build_id();
2214 if (strcmp(style, "none") == 0)
2217 // Set DESCSZ to the size of the note descriptor. When possible,
2218 // set DESC to the note descriptor contents.
2221 if (strcmp(style, "md5") == 0)
2223 else if (strcmp(style, "sha1") == 0)
2225 else if (strcmp(style, "uuid") == 0)
2227 const size_t uuidsz = 128 / 8;
2229 char buffer[uuidsz];
2230 memset(buffer, 0, uuidsz);
2232 int descriptor = open_descriptor(-1, "/dev/urandom", O_RDONLY);
2234 gold_error(_("--build-id=uuid failed: could not open /dev/urandom: %s"),
2238 ssize_t got = ::read(descriptor, buffer, uuidsz);
2239 release_descriptor(descriptor, true);
2241 gold_error(_("/dev/urandom: read failed: %s"), strerror(errno));
2242 else if (static_cast<size_t>(got) != uuidsz)
2243 gold_error(_("/dev/urandom: expected %zu bytes, got %zd bytes"),
2247 desc.assign(buffer, uuidsz);
2250 else if (strncmp(style, "0x", 2) == 0)
2253 const char* p = style + 2;
2256 if (hex_p(p[0]) && hex_p(p[1]))
2258 char c = (hex_value(p[0]) << 4) | hex_value(p[1]);
2262 else if (*p == '-' || *p == ':')
2265 gold_fatal(_("--build-id argument '%s' not a valid hex number"),
2268 descsz = desc.size();
2271 gold_fatal(_("unrecognized --build-id argument '%s'"), style);
2274 size_t trailing_padding;
2275 Output_section* os = this->create_note("GNU", elfcpp::NT_GNU_BUILD_ID,
2276 ".note.gnu.build-id", descsz, true,
2283 // We know the value already, so we fill it in now.
2284 gold_assert(desc.size() == descsz);
2286 Output_section_data* posd = new Output_data_const(desc, 4);
2287 os->add_output_section_data(posd);
2289 if (trailing_padding != 0)
2291 posd = new Output_data_zero_fill(trailing_padding, 0);
2292 os->add_output_section_data(posd);
2297 // We need to compute a checksum after we have completed the
2299 gold_assert(trailing_padding == 0);
2300 this->build_id_note_ = new Output_data_zero_fill(descsz, 4);
2301 os->add_output_section_data(this->build_id_note_);
2305 // If we have both .stabXX and .stabXXstr sections, then the sh_link
2306 // field of the former should point to the latter. I'm not sure who
2307 // started this, but the GNU linker does it, and some tools depend
2311 Layout::link_stabs_sections()
2313 if (!this->have_stabstr_section_)
2316 for (Section_list::iterator p = this->section_list_.begin();
2317 p != this->section_list_.end();
2320 if ((*p)->type() != elfcpp::SHT_STRTAB)
2323 const char* name = (*p)->name();
2324 if (strncmp(name, ".stab", 5) != 0)
2327 size_t len = strlen(name);
2328 if (strcmp(name + len - 3, "str") != 0)
2331 std::string stab_name(name, len - 3);
2332 Output_section* stab_sec;
2333 stab_sec = this->find_output_section(stab_name.c_str());
2334 if (stab_sec != NULL)
2335 stab_sec->set_link_section(*p);
2339 // Create .gnu_incremental_inputs and related sections needed
2340 // for the next run of incremental linking to check what has changed.
2343 Layout::create_incremental_info_sections(Symbol_table* symtab)
2345 Incremental_inputs* incr = this->incremental_inputs_;
2347 gold_assert(incr != NULL);
2349 // Create the .gnu_incremental_inputs, _symtab, and _relocs input sections.
2350 incr->create_data_sections(symtab);
2352 // Add the .gnu_incremental_inputs section.
2353 const char* incremental_inputs_name =
2354 this->namepool_.add(".gnu_incremental_inputs", false, NULL);
2355 Output_section* incremental_inputs_os =
2356 this->make_output_section(incremental_inputs_name,
2357 elfcpp::SHT_GNU_INCREMENTAL_INPUTS, 0,
2358 ORDER_INVALID, false);
2359 incremental_inputs_os->add_output_section_data(incr->inputs_section());
2361 // Add the .gnu_incremental_symtab section.
2362 const char* incremental_symtab_name =
2363 this->namepool_.add(".gnu_incremental_symtab", false, NULL);
2364 Output_section* incremental_symtab_os =
2365 this->make_output_section(incremental_symtab_name,
2366 elfcpp::SHT_GNU_INCREMENTAL_SYMTAB, 0,
2367 ORDER_INVALID, false);
2368 incremental_symtab_os->add_output_section_data(incr->symtab_section());
2369 incremental_symtab_os->set_entsize(4);
2371 // Add the .gnu_incremental_relocs section.
2372 const char* incremental_relocs_name =
2373 this->namepool_.add(".gnu_incremental_relocs", false, NULL);
2374 Output_section* incremental_relocs_os =
2375 this->make_output_section(incremental_relocs_name,
2376 elfcpp::SHT_GNU_INCREMENTAL_RELOCS, 0,
2377 ORDER_INVALID, false);
2378 incremental_relocs_os->add_output_section_data(incr->relocs_section());
2379 incremental_relocs_os->set_entsize(incr->relocs_entsize());
2381 // Add the .gnu_incremental_got_plt section.
2382 const char* incremental_got_plt_name =
2383 this->namepool_.add(".gnu_incremental_got_plt", false, NULL);
2384 Output_section* incremental_got_plt_os =
2385 this->make_output_section(incremental_got_plt_name,
2386 elfcpp::SHT_GNU_INCREMENTAL_GOT_PLT, 0,
2387 ORDER_INVALID, false);
2388 incremental_got_plt_os->add_output_section_data(incr->got_plt_section());
2390 // Add the .gnu_incremental_strtab section.
2391 const char* incremental_strtab_name =
2392 this->namepool_.add(".gnu_incremental_strtab", false, NULL);
2393 Output_section* incremental_strtab_os = this->make_output_section(incremental_strtab_name,
2394 elfcpp::SHT_STRTAB, 0,
2395 ORDER_INVALID, false);
2396 Output_data_strtab* strtab_data =
2397 new Output_data_strtab(incr->get_stringpool());
2398 incremental_strtab_os->add_output_section_data(strtab_data);
2400 incremental_inputs_os->set_after_input_sections();
2401 incremental_symtab_os->set_after_input_sections();
2402 incremental_relocs_os->set_after_input_sections();
2403 incremental_got_plt_os->set_after_input_sections();
2405 incremental_inputs_os->set_link_section(incremental_strtab_os);
2406 incremental_symtab_os->set_link_section(incremental_inputs_os);
2407 incremental_relocs_os->set_link_section(incremental_inputs_os);
2408 incremental_got_plt_os->set_link_section(incremental_inputs_os);
2411 // Return whether SEG1 should be before SEG2 in the output file. This
2412 // is based entirely on the segment type and flags. When this is
2413 // called the segment addresses has normally not yet been set.
2416 Layout::segment_precedes(const Output_segment* seg1,
2417 const Output_segment* seg2)
2419 elfcpp::Elf_Word type1 = seg1->type();
2420 elfcpp::Elf_Word type2 = seg2->type();
2422 // The single PT_PHDR segment is required to precede any loadable
2423 // segment. We simply make it always first.
2424 if (type1 == elfcpp::PT_PHDR)
2426 gold_assert(type2 != elfcpp::PT_PHDR);
2429 if (type2 == elfcpp::PT_PHDR)
2432 // The single PT_INTERP segment is required to precede any loadable
2433 // segment. We simply make it always second.
2434 if (type1 == elfcpp::PT_INTERP)
2436 gold_assert(type2 != elfcpp::PT_INTERP);
2439 if (type2 == elfcpp::PT_INTERP)
2442 // We then put PT_LOAD segments before any other segments.
2443 if (type1 == elfcpp::PT_LOAD && type2 != elfcpp::PT_LOAD)
2445 if (type2 == elfcpp::PT_LOAD && type1 != elfcpp::PT_LOAD)
2448 // We put the PT_TLS segment last except for the PT_GNU_RELRO
2449 // segment, because that is where the dynamic linker expects to find
2450 // it (this is just for efficiency; other positions would also work
2452 if (type1 == elfcpp::PT_TLS
2453 && type2 != elfcpp::PT_TLS
2454 && type2 != elfcpp::PT_GNU_RELRO)
2456 if (type2 == elfcpp::PT_TLS
2457 && type1 != elfcpp::PT_TLS
2458 && type1 != elfcpp::PT_GNU_RELRO)
2461 // We put the PT_GNU_RELRO segment last, because that is where the
2462 // dynamic linker expects to find it (as with PT_TLS, this is just
2464 if (type1 == elfcpp::PT_GNU_RELRO && type2 != elfcpp::PT_GNU_RELRO)
2466 if (type2 == elfcpp::PT_GNU_RELRO && type1 != elfcpp::PT_GNU_RELRO)
2469 const elfcpp::Elf_Word flags1 = seg1->flags();
2470 const elfcpp::Elf_Word flags2 = seg2->flags();
2472 // The order of non-PT_LOAD segments is unimportant. We simply sort
2473 // by the numeric segment type and flags values. There should not
2474 // be more than one segment with the same type and flags.
2475 if (type1 != elfcpp::PT_LOAD)
2478 return type1 < type2;
2479 gold_assert(flags1 != flags2);
2480 return flags1 < flags2;
2483 // If the addresses are set already, sort by load address.
2484 if (seg1->are_addresses_set())
2486 if (!seg2->are_addresses_set())
2489 unsigned int section_count1 = seg1->output_section_count();
2490 unsigned int section_count2 = seg2->output_section_count();
2491 if (section_count1 == 0 && section_count2 > 0)
2493 if (section_count1 > 0 && section_count2 == 0)
2496 uint64_t paddr1 = (seg1->are_addresses_set()
2498 : seg1->first_section_load_address());
2499 uint64_t paddr2 = (seg2->are_addresses_set()
2501 : seg2->first_section_load_address());
2503 if (paddr1 != paddr2)
2504 return paddr1 < paddr2;
2506 else if (seg2->are_addresses_set())
2509 // A segment which holds large data comes after a segment which does
2510 // not hold large data.
2511 if (seg1->is_large_data_segment())
2513 if (!seg2->is_large_data_segment())
2516 else if (seg2->is_large_data_segment())
2519 // Otherwise, we sort PT_LOAD segments based on the flags. Readonly
2520 // segments come before writable segments. Then writable segments
2521 // with data come before writable segments without data. Then
2522 // executable segments come before non-executable segments. Then
2523 // the unlikely case of a non-readable segment comes before the
2524 // normal case of a readable segment. If there are multiple
2525 // segments with the same type and flags, we require that the
2526 // address be set, and we sort by virtual address and then physical
2528 if ((flags1 & elfcpp::PF_W) != (flags2 & elfcpp::PF_W))
2529 return (flags1 & elfcpp::PF_W) == 0;
2530 if ((flags1 & elfcpp::PF_W) != 0
2531 && seg1->has_any_data_sections() != seg2->has_any_data_sections())
2532 return seg1->has_any_data_sections();
2533 if ((flags1 & elfcpp::PF_X) != (flags2 & elfcpp::PF_X))
2534 return (flags1 & elfcpp::PF_X) != 0;
2535 if ((flags1 & elfcpp::PF_R) != (flags2 & elfcpp::PF_R))
2536 return (flags1 & elfcpp::PF_R) == 0;
2538 // We shouldn't get here--we shouldn't create segments which we
2539 // can't distinguish.
2543 // Increase OFF so that it is congruent to ADDR modulo ABI_PAGESIZE.
2546 align_file_offset(off_t off, uint64_t addr, uint64_t abi_pagesize)
2548 uint64_t unsigned_off = off;
2549 uint64_t aligned_off = ((unsigned_off & ~(abi_pagesize - 1))
2550 | (addr & (abi_pagesize - 1)));
2551 if (aligned_off < unsigned_off)
2552 aligned_off += abi_pagesize;
2556 // Set the file offsets of all the segments, and all the sections they
2557 // contain. They have all been created. LOAD_SEG must be be laid out
2558 // first. Return the offset of the data to follow.
2561 Layout::set_segment_offsets(const Target* target, Output_segment* load_seg,
2562 unsigned int* pshndx)
2564 // Sort them into the final order.
2565 std::sort(this->segment_list_.begin(), this->segment_list_.end(),
2566 Layout::Compare_segments());
2568 // Find the PT_LOAD segments, and set their addresses and offsets
2569 // and their section's addresses and offsets.
2571 if (parameters->options().user_set_Ttext())
2572 addr = parameters->options().Ttext();
2573 else if (parameters->options().output_is_position_independent())
2576 addr = target->default_text_segment_address();
2579 // If LOAD_SEG is NULL, then the file header and segment headers
2580 // will not be loadable. But they still need to be at offset 0 in
2581 // the file. Set their offsets now.
2582 if (load_seg == NULL)
2584 for (Data_list::iterator p = this->special_output_list_.begin();
2585 p != this->special_output_list_.end();
2588 off = align_address(off, (*p)->addralign());
2589 (*p)->set_address_and_file_offset(0, off);
2590 off += (*p)->data_size();
2594 unsigned int increase_relro = this->increase_relro_;
2595 if (this->script_options_->saw_sections_clause())
2598 const bool check_sections = parameters->options().check_sections();
2599 Output_segment* last_load_segment = NULL;
2601 for (Segment_list::iterator p = this->segment_list_.begin();
2602 p != this->segment_list_.end();
2605 if ((*p)->type() == elfcpp::PT_LOAD)
2607 if (load_seg != NULL && load_seg != *p)
2611 bool are_addresses_set = (*p)->are_addresses_set();
2612 if (are_addresses_set)
2614 // When it comes to setting file offsets, we care about
2615 // the physical address.
2616 addr = (*p)->paddr();
2618 else if (parameters->options().user_set_Tdata()
2619 && ((*p)->flags() & elfcpp::PF_W) != 0
2620 && (!parameters->options().user_set_Tbss()
2621 || (*p)->has_any_data_sections()))
2623 addr = parameters->options().Tdata();
2624 are_addresses_set = true;
2626 else if (parameters->options().user_set_Tbss()
2627 && ((*p)->flags() & elfcpp::PF_W) != 0
2628 && !(*p)->has_any_data_sections())
2630 addr = parameters->options().Tbss();
2631 are_addresses_set = true;
2634 uint64_t orig_addr = addr;
2635 uint64_t orig_off = off;
2637 uint64_t aligned_addr = 0;
2638 uint64_t abi_pagesize = target->abi_pagesize();
2639 uint64_t common_pagesize = target->common_pagesize();
2641 if (!parameters->options().nmagic()
2642 && !parameters->options().omagic())
2643 (*p)->set_minimum_p_align(common_pagesize);
2645 if (!are_addresses_set)
2647 // Skip the address forward one page, maintaining the same
2648 // position within the page. This lets us store both segments
2649 // overlapping on a single page in the file, but the loader will
2650 // put them on different pages in memory. We will revisit this
2651 // decision once we know the size of the segment.
2653 addr = align_address(addr, (*p)->maximum_alignment());
2654 aligned_addr = addr;
2656 if ((addr & (abi_pagesize - 1)) != 0)
2657 addr = addr + abi_pagesize;
2659 off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
2662 if (!parameters->options().nmagic()
2663 && !parameters->options().omagic())
2664 off = align_file_offset(off, addr, abi_pagesize);
2665 else if (load_seg == NULL)
2667 // This is -N or -n with a section script which prevents
2668 // us from using a load segment. We need to ensure that
2669 // the file offset is aligned to the alignment of the
2670 // segment. This is because the linker script
2671 // implicitly assumed a zero offset. If we don't align
2672 // here, then the alignment of the sections in the
2673 // linker script may not match the alignment of the
2674 // sections in the set_section_addresses call below,
2675 // causing an error about dot moving backward.
2676 off = align_address(off, (*p)->maximum_alignment());
2679 unsigned int shndx_hold = *pshndx;
2680 bool has_relro = false;
2681 uint64_t new_addr = (*p)->set_section_addresses(this, false, addr,
2686 // Now that we know the size of this segment, we may be able
2687 // to save a page in memory, at the cost of wasting some
2688 // file space, by instead aligning to the start of a new
2689 // page. Here we use the real machine page size rather than
2690 // the ABI mandated page size. If the segment has been
2691 // aligned so that the relro data ends at a page boundary,
2692 // we do not try to realign it.
2694 if (!are_addresses_set && !has_relro && aligned_addr != addr)
2696 uint64_t first_off = (common_pagesize
2698 & (common_pagesize - 1)));
2699 uint64_t last_off = new_addr & (common_pagesize - 1);
2702 && ((aligned_addr & ~ (common_pagesize - 1))
2703 != (new_addr & ~ (common_pagesize - 1)))
2704 && first_off + last_off <= common_pagesize)
2706 *pshndx = shndx_hold;
2707 addr = align_address(aligned_addr, common_pagesize);
2708 addr = align_address(addr, (*p)->maximum_alignment());
2709 off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
2710 off = align_file_offset(off, addr, abi_pagesize);
2712 increase_relro = this->increase_relro_;
2713 if (this->script_options_->saw_sections_clause())
2717 new_addr = (*p)->set_section_addresses(this, true, addr,
2726 // Implement --check-sections. We know that the segments
2727 // are sorted by LMA.
2728 if (check_sections && last_load_segment != NULL)
2730 gold_assert(last_load_segment->paddr() <= (*p)->paddr());
2731 if (last_load_segment->paddr() + last_load_segment->memsz()
2734 unsigned long long lb1 = last_load_segment->paddr();
2735 unsigned long long le1 = lb1 + last_load_segment->memsz();
2736 unsigned long long lb2 = (*p)->paddr();
2737 unsigned long long le2 = lb2 + (*p)->memsz();
2738 gold_error(_("load segment overlap [0x%llx -> 0x%llx] and "
2739 "[0x%llx -> 0x%llx]"),
2740 lb1, le1, lb2, le2);
2743 last_load_segment = *p;
2747 // Handle the non-PT_LOAD segments, setting their offsets from their
2748 // section's offsets.
2749 for (Segment_list::iterator p = this->segment_list_.begin();
2750 p != this->segment_list_.end();
2753 if ((*p)->type() != elfcpp::PT_LOAD)
2754 (*p)->set_offset((*p)->type() == elfcpp::PT_GNU_RELRO
2759 // Set the TLS offsets for each section in the PT_TLS segment.
2760 if (this->tls_segment_ != NULL)
2761 this->tls_segment_->set_tls_offsets();
2766 // Set the offsets of all the allocated sections when doing a
2767 // relocatable link. This does the same jobs as set_segment_offsets,
2768 // only for a relocatable link.
2771 Layout::set_relocatable_section_offsets(Output_data* file_header,
2772 unsigned int* pshndx)
2776 file_header->set_address_and_file_offset(0, 0);
2777 off += file_header->data_size();
2779 for (Section_list::iterator p = this->section_list_.begin();
2780 p != this->section_list_.end();
2783 // We skip unallocated sections here, except that group sections
2784 // have to come first.
2785 if (((*p)->flags() & elfcpp::SHF_ALLOC) == 0
2786 && (*p)->type() != elfcpp::SHT_GROUP)
2789 off = align_address(off, (*p)->addralign());
2791 // The linker script might have set the address.
2792 if (!(*p)->is_address_valid())
2793 (*p)->set_address(0);
2794 (*p)->set_file_offset(off);
2795 (*p)->finalize_data_size();
2796 off += (*p)->data_size();
2798 (*p)->set_out_shndx(*pshndx);
2805 // Set the file offset of all the sections not associated with a
2809 Layout::set_section_offsets(off_t off, Layout::Section_offset_pass pass)
2811 for (Section_list::iterator p = this->unattached_section_list_.begin();
2812 p != this->unattached_section_list_.end();
2815 // The symtab section is handled in create_symtab_sections.
2816 if (*p == this->symtab_section_)
2819 // If we've already set the data size, don't set it again.
2820 if ((*p)->is_offset_valid() && (*p)->is_data_size_valid())
2823 if (pass == BEFORE_INPUT_SECTIONS_PASS
2824 && (*p)->requires_postprocessing())
2826 (*p)->create_postprocessing_buffer();
2827 this->any_postprocessing_sections_ = true;
2830 if (pass == BEFORE_INPUT_SECTIONS_PASS
2831 && (*p)->after_input_sections())
2833 else if (pass == POSTPROCESSING_SECTIONS_PASS
2834 && (!(*p)->after_input_sections()
2835 || (*p)->type() == elfcpp::SHT_STRTAB))
2837 else if (pass == STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
2838 && (!(*p)->after_input_sections()
2839 || (*p)->type() != elfcpp::SHT_STRTAB))
2842 off = align_address(off, (*p)->addralign());
2843 (*p)->set_file_offset(off);
2844 (*p)->finalize_data_size();
2845 off += (*p)->data_size();
2847 // At this point the name must be set.
2848 if (pass != STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS)
2849 this->namepool_.add((*p)->name(), false, NULL);
2854 // Set the section indexes of all the sections not associated with a
2858 Layout::set_section_indexes(unsigned int shndx)
2860 for (Section_list::iterator p = this->unattached_section_list_.begin();
2861 p != this->unattached_section_list_.end();
2864 if (!(*p)->has_out_shndx())
2866 (*p)->set_out_shndx(shndx);
2873 // Set the section addresses according to the linker script. This is
2874 // only called when we see a SECTIONS clause. This returns the
2875 // program segment which should hold the file header and segment
2876 // headers, if any. It will return NULL if they should not be in a
2880 Layout::set_section_addresses_from_script(Symbol_table* symtab)
2882 Script_sections* ss = this->script_options_->script_sections();
2883 gold_assert(ss->saw_sections_clause());
2884 return this->script_options_->set_section_addresses(symtab, this);
2887 // Place the orphan sections in the linker script.
2890 Layout::place_orphan_sections_in_script()
2892 Script_sections* ss = this->script_options_->script_sections();
2893 gold_assert(ss->saw_sections_clause());
2895 // Place each orphaned output section in the script.
2896 for (Section_list::iterator p = this->section_list_.begin();
2897 p != this->section_list_.end();
2900 if (!(*p)->found_in_sections_clause())
2901 ss->place_orphan(*p);
2905 // Count the local symbols in the regular symbol table and the dynamic
2906 // symbol table, and build the respective string pools.
2909 Layout::count_local_symbols(const Task* task,
2910 const Input_objects* input_objects)
2912 // First, figure out an upper bound on the number of symbols we'll
2913 // be inserting into each pool. This helps us create the pools with
2914 // the right size, to avoid unnecessary hashtable resizing.
2915 unsigned int symbol_count = 0;
2916 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
2917 p != input_objects->relobj_end();
2919 symbol_count += (*p)->local_symbol_count();
2921 // Go from "upper bound" to "estimate." We overcount for two
2922 // reasons: we double-count symbols that occur in more than one
2923 // object file, and we count symbols that are dropped from the
2924 // output. Add it all together and assume we overcount by 100%.
2927 // We assume all symbols will go into both the sympool and dynpool.
2928 this->sympool_.reserve(symbol_count);
2929 this->dynpool_.reserve(symbol_count);
2931 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
2932 p != input_objects->relobj_end();
2935 Task_lock_obj<Object> tlo(task, *p);
2936 (*p)->count_local_symbols(&this->sympool_, &this->dynpool_);
2940 // Create the symbol table sections. Here we also set the final
2941 // values of the symbols. At this point all the loadable sections are
2942 // fully laid out. SHNUM is the number of sections so far.
2945 Layout::create_symtab_sections(const Input_objects* input_objects,
2946 Symbol_table* symtab,
2952 if (parameters->target().get_size() == 32)
2954 symsize = elfcpp::Elf_sizes<32>::sym_size;
2957 else if (parameters->target().get_size() == 64)
2959 symsize = elfcpp::Elf_sizes<64>::sym_size;
2966 off = align_address(off, align);
2967 off_t startoff = off;
2969 // Save space for the dummy symbol at the start of the section. We
2970 // never bother to write this out--it will just be left as zero.
2972 unsigned int local_symbol_index = 1;
2974 // Add STT_SECTION symbols for each Output section which needs one.
2975 for (Section_list::iterator p = this->section_list_.begin();
2976 p != this->section_list_.end();
2979 if (!(*p)->needs_symtab_index())
2980 (*p)->set_symtab_index(-1U);
2983 (*p)->set_symtab_index(local_symbol_index);
2984 ++local_symbol_index;
2989 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
2990 p != input_objects->relobj_end();
2993 unsigned int index = (*p)->finalize_local_symbols(local_symbol_index,
2995 off += (index - local_symbol_index) * symsize;
2996 local_symbol_index = index;
2999 unsigned int local_symcount = local_symbol_index;
3000 gold_assert(static_cast<off_t>(local_symcount * symsize) == off - startoff);
3003 size_t dyn_global_index;
3005 if (this->dynsym_section_ == NULL)
3008 dyn_global_index = 0;
3013 dyn_global_index = this->dynsym_section_->info();
3014 off_t locsize = dyn_global_index * this->dynsym_section_->entsize();
3015 dynoff = this->dynsym_section_->offset() + locsize;
3016 dyncount = (this->dynsym_section_->data_size() - locsize) / symsize;
3017 gold_assert(static_cast<off_t>(dyncount * symsize)
3018 == this->dynsym_section_->data_size() - locsize);
3021 off = symtab->finalize(off, dynoff, dyn_global_index, dyncount,
3022 &this->sympool_, &local_symcount);
3024 if (!parameters->options().strip_all())
3026 this->sympool_.set_string_offsets();
3028 const char* symtab_name = this->namepool_.add(".symtab", false, NULL);
3029 Output_section* osymtab = this->make_output_section(symtab_name,
3033 this->symtab_section_ = osymtab;
3035 Output_section_data* pos = new Output_data_fixed_space(off - startoff,
3038 osymtab->add_output_section_data(pos);
3040 // We generate a .symtab_shndx section if we have more than
3041 // SHN_LORESERVE sections. Technically it is possible that we
3042 // don't need one, because it is possible that there are no
3043 // symbols in any of sections with indexes larger than
3044 // SHN_LORESERVE. That is probably unusual, though, and it is
3045 // easier to always create one than to compute section indexes
3046 // twice (once here, once when writing out the symbols).
3047 if (shnum >= elfcpp::SHN_LORESERVE)
3049 const char* symtab_xindex_name = this->namepool_.add(".symtab_shndx",
3051 Output_section* osymtab_xindex =
3052 this->make_output_section(symtab_xindex_name,
3053 elfcpp::SHT_SYMTAB_SHNDX, 0,
3054 ORDER_INVALID, false);
3056 size_t symcount = (off - startoff) / symsize;
3057 this->symtab_xindex_ = new Output_symtab_xindex(symcount);
3059 osymtab_xindex->add_output_section_data(this->symtab_xindex_);
3061 osymtab_xindex->set_link_section(osymtab);
3062 osymtab_xindex->set_addralign(4);
3063 osymtab_xindex->set_entsize(4);
3065 osymtab_xindex->set_after_input_sections();
3067 // This tells the driver code to wait until the symbol table
3068 // has written out before writing out the postprocessing
3069 // sections, including the .symtab_shndx section.
3070 this->any_postprocessing_sections_ = true;
3073 const char* strtab_name = this->namepool_.add(".strtab", false, NULL);
3074 Output_section* ostrtab = this->make_output_section(strtab_name,
3079 Output_section_data* pstr = new Output_data_strtab(&this->sympool_);
3080 ostrtab->add_output_section_data(pstr);
3082 osymtab->set_file_offset(startoff);
3083 osymtab->finalize_data_size();
3084 osymtab->set_link_section(ostrtab);
3085 osymtab->set_info(local_symcount);
3086 osymtab->set_entsize(symsize);
3092 // Create the .shstrtab section, which holds the names of the
3093 // sections. At the time this is called, we have created all the
3094 // output sections except .shstrtab itself.
3097 Layout::create_shstrtab()
3099 // FIXME: We don't need to create a .shstrtab section if we are
3100 // stripping everything.
3102 const char* name = this->namepool_.add(".shstrtab", false, NULL);
3104 Output_section* os = this->make_output_section(name, elfcpp::SHT_STRTAB, 0,
3105 ORDER_INVALID, false);
3107 if (strcmp(parameters->options().compress_debug_sections(), "none") != 0)
3109 // We can't write out this section until we've set all the
3110 // section names, and we don't set the names of compressed
3111 // output sections until relocations are complete. FIXME: With
3112 // the current names we use, this is unnecessary.
3113 os->set_after_input_sections();
3116 Output_section_data* posd = new Output_data_strtab(&this->namepool_);
3117 os->add_output_section_data(posd);
3122 // Create the section headers. SIZE is 32 or 64. OFF is the file
3126 Layout::create_shdrs(const Output_section* shstrtab_section, off_t* poff)
3128 Output_section_headers* oshdrs;
3129 oshdrs = new Output_section_headers(this,
3130 &this->segment_list_,
3131 &this->section_list_,
3132 &this->unattached_section_list_,
3135 off_t off = align_address(*poff, oshdrs->addralign());
3136 oshdrs->set_address_and_file_offset(0, off);
3137 off += oshdrs->data_size();
3139 this->section_headers_ = oshdrs;
3142 // Count the allocated sections.
3145 Layout::allocated_output_section_count() const
3147 size_t section_count = 0;
3148 for (Segment_list::const_iterator p = this->segment_list_.begin();
3149 p != this->segment_list_.end();
3151 section_count += (*p)->output_section_count();
3152 return section_count;
3155 // Create the dynamic symbol table.
3158 Layout::create_dynamic_symtab(const Input_objects* input_objects,
3159 Symbol_table* symtab,
3160 Output_section** pdynstr,
3161 unsigned int* plocal_dynamic_count,
3162 std::vector<Symbol*>* pdynamic_symbols,
3163 Versions* pversions)
3165 // Count all the symbols in the dynamic symbol table, and set the
3166 // dynamic symbol indexes.
3168 // Skip symbol 0, which is always all zeroes.
3169 unsigned int index = 1;
3171 // Add STT_SECTION symbols for each Output section which needs one.
3172 for (Section_list::iterator p = this->section_list_.begin();
3173 p != this->section_list_.end();
3176 if (!(*p)->needs_dynsym_index())
3177 (*p)->set_dynsym_index(-1U);
3180 (*p)->set_dynsym_index(index);
3185 // Count the local symbols that need to go in the dynamic symbol table,
3186 // and set the dynamic symbol indexes.
3187 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
3188 p != input_objects->relobj_end();
3191 unsigned int new_index = (*p)->set_local_dynsym_indexes(index);
3195 unsigned int local_symcount = index;
3196 *plocal_dynamic_count = local_symcount;
3198 index = symtab->set_dynsym_indexes(index, pdynamic_symbols,
3199 &this->dynpool_, pversions);
3203 const int size = parameters->target().get_size();
3206 symsize = elfcpp::Elf_sizes<32>::sym_size;
3209 else if (size == 64)
3211 symsize = elfcpp::Elf_sizes<64>::sym_size;
3217 // Create the dynamic symbol table section.
3219 Output_section* dynsym = this->choose_output_section(NULL, ".dynsym",
3223 ORDER_DYNAMIC_LINKER,
3226 Output_section_data* odata = new Output_data_fixed_space(index * symsize,
3229 dynsym->add_output_section_data(odata);
3231 dynsym->set_info(local_symcount);
3232 dynsym->set_entsize(symsize);
3233 dynsym->set_addralign(align);
3235 this->dynsym_section_ = dynsym;
3237 Output_data_dynamic* const odyn = this->dynamic_data_;
3238 odyn->add_section_address(elfcpp::DT_SYMTAB, dynsym);
3239 odyn->add_constant(elfcpp::DT_SYMENT, symsize);
3241 // If there are more than SHN_LORESERVE allocated sections, we
3242 // create a .dynsym_shndx section. It is possible that we don't
3243 // need one, because it is possible that there are no dynamic
3244 // symbols in any of the sections with indexes larger than
3245 // SHN_LORESERVE. This is probably unusual, though, and at this
3246 // time we don't know the actual section indexes so it is
3247 // inconvenient to check.
3248 if (this->allocated_output_section_count() >= elfcpp::SHN_LORESERVE)
3250 Output_section* dynsym_xindex =
3251 this->choose_output_section(NULL, ".dynsym_shndx",
3252 elfcpp::SHT_SYMTAB_SHNDX,
3254 false, ORDER_DYNAMIC_LINKER, false);
3256 this->dynsym_xindex_ = new Output_symtab_xindex(index);
3258 dynsym_xindex->add_output_section_data(this->dynsym_xindex_);
3260 dynsym_xindex->set_link_section(dynsym);
3261 dynsym_xindex->set_addralign(4);
3262 dynsym_xindex->set_entsize(4);
3264 dynsym_xindex->set_after_input_sections();
3266 // This tells the driver code to wait until the symbol table has
3267 // written out before writing out the postprocessing sections,
3268 // including the .dynsym_shndx section.
3269 this->any_postprocessing_sections_ = true;
3272 // Create the dynamic string table section.
3274 Output_section* dynstr = this->choose_output_section(NULL, ".dynstr",
3278 ORDER_DYNAMIC_LINKER,
3281 Output_section_data* strdata = new Output_data_strtab(&this->dynpool_);
3282 dynstr->add_output_section_data(strdata);
3284 dynsym->set_link_section(dynstr);
3285 this->dynamic_section_->set_link_section(dynstr);
3287 odyn->add_section_address(elfcpp::DT_STRTAB, dynstr);
3288 odyn->add_section_size(elfcpp::DT_STRSZ, dynstr);
3292 // Create the hash tables.
3294 if (strcmp(parameters->options().hash_style(), "sysv") == 0
3295 || strcmp(parameters->options().hash_style(), "both") == 0)
3297 unsigned char* phash;
3298 unsigned int hashlen;
3299 Dynobj::create_elf_hash_table(*pdynamic_symbols, local_symcount,
3302 Output_section* hashsec =
3303 this->choose_output_section(NULL, ".hash", elfcpp::SHT_HASH,
3304 elfcpp::SHF_ALLOC, false,
3305 ORDER_DYNAMIC_LINKER, false);
3307 Output_section_data* hashdata = new Output_data_const_buffer(phash,
3311 hashsec->add_output_section_data(hashdata);
3313 hashsec->set_link_section(dynsym);
3314 hashsec->set_entsize(4);
3316 odyn->add_section_address(elfcpp::DT_HASH, hashsec);
3319 if (strcmp(parameters->options().hash_style(), "gnu") == 0
3320 || strcmp(parameters->options().hash_style(), "both") == 0)
3322 unsigned char* phash;
3323 unsigned int hashlen;
3324 Dynobj::create_gnu_hash_table(*pdynamic_symbols, local_symcount,
3327 Output_section* hashsec =
3328 this->choose_output_section(NULL, ".gnu.hash", elfcpp::SHT_GNU_HASH,
3329 elfcpp::SHF_ALLOC, false,
3330 ORDER_DYNAMIC_LINKER, false);
3332 Output_section_data* hashdata = new Output_data_const_buffer(phash,
3336 hashsec->add_output_section_data(hashdata);
3338 hashsec->set_link_section(dynsym);
3340 // For a 64-bit target, the entries in .gnu.hash do not have a
3341 // uniform size, so we only set the entry size for a 32-bit
3343 if (parameters->target().get_size() == 32)
3344 hashsec->set_entsize(4);
3346 odyn->add_section_address(elfcpp::DT_GNU_HASH, hashsec);
3350 // Assign offsets to each local portion of the dynamic symbol table.
3353 Layout::assign_local_dynsym_offsets(const Input_objects* input_objects)
3355 Output_section* dynsym = this->dynsym_section_;
3356 gold_assert(dynsym != NULL);
3358 off_t off = dynsym->offset();
3360 // Skip the dummy symbol at the start of the section.
3361 off += dynsym->entsize();
3363 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
3364 p != input_objects->relobj_end();
3367 unsigned int count = (*p)->set_local_dynsym_offset(off);
3368 off += count * dynsym->entsize();
3372 // Create the version sections.
3375 Layout::create_version_sections(const Versions* versions,
3376 const Symbol_table* symtab,
3377 unsigned int local_symcount,
3378 const std::vector<Symbol*>& dynamic_symbols,
3379 const Output_section* dynstr)
3381 if (!versions->any_defs() && !versions->any_needs())
3384 switch (parameters->size_and_endianness())
3386 #ifdef HAVE_TARGET_32_LITTLE
3387 case Parameters::TARGET_32_LITTLE:
3388 this->sized_create_version_sections<32, false>(versions, symtab,
3390 dynamic_symbols, dynstr);
3393 #ifdef HAVE_TARGET_32_BIG
3394 case Parameters::TARGET_32_BIG:
3395 this->sized_create_version_sections<32, true>(versions, symtab,
3397 dynamic_symbols, dynstr);
3400 #ifdef HAVE_TARGET_64_LITTLE
3401 case Parameters::TARGET_64_LITTLE:
3402 this->sized_create_version_sections<64, false>(versions, symtab,
3404 dynamic_symbols, dynstr);
3407 #ifdef HAVE_TARGET_64_BIG
3408 case Parameters::TARGET_64_BIG:
3409 this->sized_create_version_sections<64, true>(versions, symtab,
3411 dynamic_symbols, dynstr);
3419 // Create the version sections, sized version.
3421 template<int size, bool big_endian>
3423 Layout::sized_create_version_sections(
3424 const Versions* versions,
3425 const Symbol_table* symtab,
3426 unsigned int local_symcount,
3427 const std::vector<Symbol*>& dynamic_symbols,
3428 const Output_section* dynstr)
3430 Output_section* vsec = this->choose_output_section(NULL, ".gnu.version",
3431 elfcpp::SHT_GNU_versym,
3434 ORDER_DYNAMIC_LINKER,
3437 unsigned char* vbuf;
3439 versions->symbol_section_contents<size, big_endian>(symtab, &this->dynpool_,
3444 Output_section_data* vdata = new Output_data_const_buffer(vbuf, vsize, 2,
3447 vsec->add_output_section_data(vdata);
3448 vsec->set_entsize(2);
3449 vsec->set_link_section(this->dynsym_section_);
3451 Output_data_dynamic* const odyn = this->dynamic_data_;
3452 odyn->add_section_address(elfcpp::DT_VERSYM, vsec);
3454 if (versions->any_defs())
3456 Output_section* vdsec;
3457 vdsec= this->choose_output_section(NULL, ".gnu.version_d",
3458 elfcpp::SHT_GNU_verdef,
3460 false, ORDER_DYNAMIC_LINKER, false);
3462 unsigned char* vdbuf;
3463 unsigned int vdsize;
3464 unsigned int vdentries;
3465 versions->def_section_contents<size, big_endian>(&this->dynpool_, &vdbuf,
3466 &vdsize, &vdentries);
3468 Output_section_data* vddata =
3469 new Output_data_const_buffer(vdbuf, vdsize, 4, "** version defs");
3471 vdsec->add_output_section_data(vddata);
3472 vdsec->set_link_section(dynstr);
3473 vdsec->set_info(vdentries);
3475 odyn->add_section_address(elfcpp::DT_VERDEF, vdsec);
3476 odyn->add_constant(elfcpp::DT_VERDEFNUM, vdentries);
3479 if (versions->any_needs())
3481 Output_section* vnsec;
3482 vnsec = this->choose_output_section(NULL, ".gnu.version_r",
3483 elfcpp::SHT_GNU_verneed,
3485 false, ORDER_DYNAMIC_LINKER, false);
3487 unsigned char* vnbuf;
3488 unsigned int vnsize;
3489 unsigned int vnentries;
3490 versions->need_section_contents<size, big_endian>(&this->dynpool_,
3494 Output_section_data* vndata =
3495 new Output_data_const_buffer(vnbuf, vnsize, 4, "** version refs");
3497 vnsec->add_output_section_data(vndata);
3498 vnsec->set_link_section(dynstr);
3499 vnsec->set_info(vnentries);
3501 odyn->add_section_address(elfcpp::DT_VERNEED, vnsec);
3502 odyn->add_constant(elfcpp::DT_VERNEEDNUM, vnentries);
3506 // Create the .interp section and PT_INTERP segment.
3509 Layout::create_interp(const Target* target)
3511 const char* interp = parameters->options().dynamic_linker();
3514 interp = target->dynamic_linker();
3515 gold_assert(interp != NULL);
3518 size_t len = strlen(interp) + 1;
3520 Output_section_data* odata = new Output_data_const(interp, len, 1);
3522 Output_section* osec = this->choose_output_section(NULL, ".interp",
3523 elfcpp::SHT_PROGBITS,
3525 false, ORDER_INTERP,
3527 osec->add_output_section_data(odata);
3529 if (!this->script_options_->saw_phdrs_clause())
3531 Output_segment* oseg = this->make_output_segment(elfcpp::PT_INTERP,
3533 oseg->add_output_section_to_nonload(osec, elfcpp::PF_R);
3537 // Add dynamic tags for the PLT and the dynamic relocs. This is
3538 // called by the target-specific code. This does nothing if not doing
3541 // USE_REL is true for REL relocs rather than RELA relocs.
3543 // If PLT_GOT is not NULL, then DT_PLTGOT points to it.
3545 // If PLT_REL is not NULL, it is used for DT_PLTRELSZ, and DT_JMPREL,
3546 // and we also set DT_PLTREL. We use PLT_REL's output section, since
3547 // some targets have multiple reloc sections in PLT_REL.
3549 // If DYN_REL is not NULL, it is used for DT_REL/DT_RELA,
3550 // DT_RELSZ/DT_RELASZ, DT_RELENT/DT_RELAENT.
3552 // If ADD_DEBUG is true, we add a DT_DEBUG entry when generating an
3556 Layout::add_target_dynamic_tags(bool use_rel, const Output_data* plt_got,
3557 const Output_data* plt_rel,
3558 const Output_data_reloc_generic* dyn_rel,
3559 bool add_debug, bool dynrel_includes_plt)
3561 Output_data_dynamic* odyn = this->dynamic_data_;
3565 if (plt_got != NULL && plt_got->output_section() != NULL)
3566 odyn->add_section_address(elfcpp::DT_PLTGOT, plt_got);
3568 if (plt_rel != NULL && plt_rel->output_section() != NULL)
3570 odyn->add_section_size(elfcpp::DT_PLTRELSZ, plt_rel->output_section());
3571 odyn->add_section_address(elfcpp::DT_JMPREL, plt_rel->output_section());
3572 odyn->add_constant(elfcpp::DT_PLTREL,
3573 use_rel ? elfcpp::DT_REL : elfcpp::DT_RELA);
3576 if (dyn_rel != NULL && dyn_rel->output_section() != NULL)
3578 odyn->add_section_address(use_rel ? elfcpp::DT_REL : elfcpp::DT_RELA,
3580 if (plt_rel != NULL && dynrel_includes_plt)
3581 odyn->add_section_size(use_rel ? elfcpp::DT_RELSZ : elfcpp::DT_RELASZ,
3584 odyn->add_section_size(use_rel ? elfcpp::DT_RELSZ : elfcpp::DT_RELASZ,
3586 const int size = parameters->target().get_size();
3591 rel_tag = elfcpp::DT_RELENT;
3593 rel_size = Reloc_types<elfcpp::SHT_REL, 32, false>::reloc_size;
3594 else if (size == 64)
3595 rel_size = Reloc_types<elfcpp::SHT_REL, 64, false>::reloc_size;
3601 rel_tag = elfcpp::DT_RELAENT;
3603 rel_size = Reloc_types<elfcpp::SHT_RELA, 32, false>::reloc_size;
3604 else if (size == 64)
3605 rel_size = Reloc_types<elfcpp::SHT_RELA, 64, false>::reloc_size;
3609 odyn->add_constant(rel_tag, rel_size);
3611 if (parameters->options().combreloc())
3613 size_t c = dyn_rel->relative_reloc_count();
3615 odyn->add_constant((use_rel
3616 ? elfcpp::DT_RELCOUNT
3617 : elfcpp::DT_RELACOUNT),
3622 if (add_debug && !parameters->options().shared())
3624 // The value of the DT_DEBUG tag is filled in by the dynamic
3625 // linker at run time, and used by the debugger.
3626 odyn->add_constant(elfcpp::DT_DEBUG, 0);
3630 // Finish the .dynamic section and PT_DYNAMIC segment.
3633 Layout::finish_dynamic_section(const Input_objects* input_objects,
3634 const Symbol_table* symtab)
3636 if (!this->script_options_->saw_phdrs_clause())
3638 Output_segment* oseg = this->make_output_segment(elfcpp::PT_DYNAMIC,
3641 oseg->add_output_section_to_nonload(this->dynamic_section_,
3642 elfcpp::PF_R | elfcpp::PF_W);
3645 Output_data_dynamic* const odyn = this->dynamic_data_;
3647 for (Input_objects::Dynobj_iterator p = input_objects->dynobj_begin();
3648 p != input_objects->dynobj_end();
3651 if (!(*p)->is_needed()
3652 && (*p)->input_file()->options().as_needed())
3654 // This dynamic object was linked with --as-needed, but it
3659 odyn->add_string(elfcpp::DT_NEEDED, (*p)->soname());
3662 if (parameters->options().shared())
3664 const char* soname = parameters->options().soname();
3666 odyn->add_string(elfcpp::DT_SONAME, soname);
3669 Symbol* sym = symtab->lookup(parameters->options().init());
3670 if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj())
3671 odyn->add_symbol(elfcpp::DT_INIT, sym);
3673 sym = symtab->lookup(parameters->options().fini());
3674 if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj())
3675 odyn->add_symbol(elfcpp::DT_FINI, sym);
3677 // Look for .init_array, .preinit_array and .fini_array by checking
3679 for(Layout::Section_list::const_iterator p = this->section_list_.begin();
3680 p != this->section_list_.end();
3682 switch((*p)->type())
3684 case elfcpp::SHT_FINI_ARRAY:
3685 odyn->add_section_address(elfcpp::DT_FINI_ARRAY, *p);
3686 odyn->add_section_size(elfcpp::DT_FINI_ARRAYSZ, *p);
3688 case elfcpp::SHT_INIT_ARRAY:
3689 odyn->add_section_address(elfcpp::DT_INIT_ARRAY, *p);
3690 odyn->add_section_size(elfcpp::DT_INIT_ARRAYSZ, *p);
3692 case elfcpp::SHT_PREINIT_ARRAY:
3693 odyn->add_section_address(elfcpp::DT_PREINIT_ARRAY, *p);
3694 odyn->add_section_size(elfcpp::DT_PREINIT_ARRAYSZ, *p);
3700 // Add a DT_RPATH entry if needed.
3701 const General_options::Dir_list& rpath(parameters->options().rpath());
3704 std::string rpath_val;
3705 for (General_options::Dir_list::const_iterator p = rpath.begin();
3709 if (rpath_val.empty())
3710 rpath_val = p->name();
3713 // Eliminate duplicates.
3714 General_options::Dir_list::const_iterator q;
3715 for (q = rpath.begin(); q != p; ++q)
3716 if (q->name() == p->name())
3721 rpath_val += p->name();
3726 odyn->add_string(elfcpp::DT_RPATH, rpath_val);
3727 if (parameters->options().enable_new_dtags())
3728 odyn->add_string(elfcpp::DT_RUNPATH, rpath_val);
3731 // Look for text segments that have dynamic relocations.
3732 bool have_textrel = false;
3733 if (!this->script_options_->saw_sections_clause())
3735 for (Segment_list::const_iterator p = this->segment_list_.begin();
3736 p != this->segment_list_.end();
3739 if (((*p)->flags() & elfcpp::PF_W) == 0
3740 && (*p)->has_dynamic_reloc())
3742 have_textrel = true;
3749 // We don't know the section -> segment mapping, so we are
3750 // conservative and just look for readonly sections with
3751 // relocations. If those sections wind up in writable segments,
3752 // then we have created an unnecessary DT_TEXTREL entry.
3753 for (Section_list::const_iterator p = this->section_list_.begin();
3754 p != this->section_list_.end();
3757 if (((*p)->flags() & elfcpp::SHF_ALLOC) != 0
3758 && ((*p)->flags() & elfcpp::SHF_WRITE) == 0
3759 && ((*p)->has_dynamic_reloc()))
3761 have_textrel = true;
3767 // Add a DT_FLAGS entry. We add it even if no flags are set so that
3768 // post-link tools can easily modify these flags if desired.
3769 unsigned int flags = 0;
3772 // Add a DT_TEXTREL for compatibility with older loaders.
3773 odyn->add_constant(elfcpp::DT_TEXTREL, 0);
3774 flags |= elfcpp::DF_TEXTREL;
3776 if (parameters->options().text())
3777 gold_error(_("read-only segment has dynamic relocations"));
3778 else if (parameters->options().warn_shared_textrel()
3779 && parameters->options().shared())
3780 gold_warning(_("shared library text segment is not shareable"));
3782 if (parameters->options().shared() && this->has_static_tls())
3783 flags |= elfcpp::DF_STATIC_TLS;
3784 if (parameters->options().origin())
3785 flags |= elfcpp::DF_ORIGIN;
3786 if (parameters->options().Bsymbolic())
3788 flags |= elfcpp::DF_SYMBOLIC;
3789 // Add DT_SYMBOLIC for compatibility with older loaders.
3790 odyn->add_constant(elfcpp::DT_SYMBOLIC, 0);
3792 if (parameters->options().now())
3793 flags |= elfcpp::DF_BIND_NOW;
3794 odyn->add_constant(elfcpp::DT_FLAGS, flags);
3797 if (parameters->options().initfirst())
3798 flags |= elfcpp::DF_1_INITFIRST;
3799 if (parameters->options().interpose())
3800 flags |= elfcpp::DF_1_INTERPOSE;
3801 if (parameters->options().loadfltr())
3802 flags |= elfcpp::DF_1_LOADFLTR;
3803 if (parameters->options().nodefaultlib())
3804 flags |= elfcpp::DF_1_NODEFLIB;
3805 if (parameters->options().nodelete())
3806 flags |= elfcpp::DF_1_NODELETE;
3807 if (parameters->options().nodlopen())
3808 flags |= elfcpp::DF_1_NOOPEN;
3809 if (parameters->options().nodump())
3810 flags |= elfcpp::DF_1_NODUMP;
3811 if (!parameters->options().shared())
3812 flags &= ~(elfcpp::DF_1_INITFIRST
3813 | elfcpp::DF_1_NODELETE
3814 | elfcpp::DF_1_NOOPEN);
3815 if (parameters->options().origin())
3816 flags |= elfcpp::DF_1_ORIGIN;
3817 if (parameters->options().now())
3818 flags |= elfcpp::DF_1_NOW;
3820 odyn->add_constant(elfcpp::DT_FLAGS_1, flags);
3823 // Set the size of the _DYNAMIC symbol table to be the size of the
3827 Layout::set_dynamic_symbol_size(const Symbol_table* symtab)
3829 Output_data_dynamic* const odyn = this->dynamic_data_;
3830 odyn->finalize_data_size();
3831 off_t data_size = odyn->data_size();
3832 const int size = parameters->target().get_size();
3834 symtab->get_sized_symbol<32>(this->dynamic_symbol_)->set_symsize(data_size);
3835 else if (size == 64)
3836 symtab->get_sized_symbol<64>(this->dynamic_symbol_)->set_symsize(data_size);
3841 // The mapping of input section name prefixes to output section names.
3842 // In some cases one prefix is itself a prefix of another prefix; in
3843 // such a case the longer prefix must come first. These prefixes are
3844 // based on the GNU linker default ELF linker script.
3846 #define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 }
3847 const Layout::Section_name_mapping Layout::section_name_mapping[] =
3849 MAPPING_INIT(".text.", ".text"),
3850 MAPPING_INIT(".ctors.", ".ctors"),
3851 MAPPING_INIT(".dtors.", ".dtors"),
3852 MAPPING_INIT(".rodata.", ".rodata"),
3853 MAPPING_INIT(".data.rel.ro.local", ".data.rel.ro.local"),
3854 MAPPING_INIT(".data.rel.ro", ".data.rel.ro"),
3855 MAPPING_INIT(".data.", ".data"),
3856 MAPPING_INIT(".bss.", ".bss"),
3857 MAPPING_INIT(".tdata.", ".tdata"),
3858 MAPPING_INIT(".tbss.", ".tbss"),
3859 MAPPING_INIT(".init_array.", ".init_array"),
3860 MAPPING_INIT(".fini_array.", ".fini_array"),
3861 MAPPING_INIT(".sdata.", ".sdata"),
3862 MAPPING_INIT(".sbss.", ".sbss"),
3863 // FIXME: In the GNU linker, .sbss2 and .sdata2 are handled
3864 // differently depending on whether it is creating a shared library.
3865 MAPPING_INIT(".sdata2.", ".sdata"),
3866 MAPPING_INIT(".sbss2.", ".sbss"),
3867 MAPPING_INIT(".lrodata.", ".lrodata"),
3868 MAPPING_INIT(".ldata.", ".ldata"),
3869 MAPPING_INIT(".lbss.", ".lbss"),
3870 MAPPING_INIT(".gcc_except_table.", ".gcc_except_table"),
3871 MAPPING_INIT(".gnu.linkonce.d.rel.ro.local.", ".data.rel.ro.local"),
3872 MAPPING_INIT(".gnu.linkonce.d.rel.ro.", ".data.rel.ro"),
3873 MAPPING_INIT(".gnu.linkonce.t.", ".text"),
3874 MAPPING_INIT(".gnu.linkonce.r.", ".rodata"),
3875 MAPPING_INIT(".gnu.linkonce.d.", ".data"),
3876 MAPPING_INIT(".gnu.linkonce.b.", ".bss"),
3877 MAPPING_INIT(".gnu.linkonce.s.", ".sdata"),
3878 MAPPING_INIT(".gnu.linkonce.sb.", ".sbss"),
3879 MAPPING_INIT(".gnu.linkonce.s2.", ".sdata"),
3880 MAPPING_INIT(".gnu.linkonce.sb2.", ".sbss"),
3881 MAPPING_INIT(".gnu.linkonce.wi.", ".debug_info"),
3882 MAPPING_INIT(".gnu.linkonce.td.", ".tdata"),
3883 MAPPING_INIT(".gnu.linkonce.tb.", ".tbss"),
3884 MAPPING_INIT(".gnu.linkonce.lr.", ".lrodata"),
3885 MAPPING_INIT(".gnu.linkonce.l.", ".ldata"),
3886 MAPPING_INIT(".gnu.linkonce.lb.", ".lbss"),
3887 MAPPING_INIT(".ARM.extab", ".ARM.extab"),
3888 MAPPING_INIT(".gnu.linkonce.armextab.", ".ARM.extab"),
3889 MAPPING_INIT(".ARM.exidx", ".ARM.exidx"),
3890 MAPPING_INIT(".gnu.linkonce.armexidx.", ".ARM.exidx"),
3894 const int Layout::section_name_mapping_count =
3895 (sizeof(Layout::section_name_mapping)
3896 / sizeof(Layout::section_name_mapping[0]));
3898 // Choose the output section name to use given an input section name.
3899 // Set *PLEN to the length of the name. *PLEN is initialized to the
3903 Layout::output_section_name(const char* name, size_t* plen)
3905 // gcc 4.3 generates the following sorts of section names when it
3906 // needs a section name specific to a function:
3912 // .data.rel.local.FN
3914 // .data.rel.ro.local.FN
3921 // The GNU linker maps all of those to the part before the .FN,
3922 // except that .data.rel.local.FN is mapped to .data, and
3923 // .data.rel.ro.local.FN is mapped to .data.rel.ro. The sections
3924 // beginning with .data.rel.ro.local are grouped together.
3926 // For an anonymous namespace, the string FN can contain a '.'.
3928 // Also of interest: .rodata.strN.N, .rodata.cstN, both of which the
3929 // GNU linker maps to .rodata.
3931 // The .data.rel.ro sections are used with -z relro. The sections
3932 // are recognized by name. We use the same names that the GNU
3933 // linker does for these sections.
3935 // It is hard to handle this in a principled way, so we don't even
3936 // try. We use a table of mappings. If the input section name is
3937 // not found in the table, we simply use it as the output section
3940 const Section_name_mapping* psnm = section_name_mapping;
3941 for (int i = 0; i < section_name_mapping_count; ++i, ++psnm)
3943 if (strncmp(name, psnm->from, psnm->fromlen) == 0)
3945 *plen = psnm->tolen;
3950 // Compressed debug sections should be mapped to the corresponding
3951 // uncompressed section.
3952 if (is_compressed_debug_section(name))
3954 size_t len = strlen(name);
3955 char* uncompressed_name = new char[len];
3956 uncompressed_name[0] = '.';
3957 gold_assert(name[0] == '.' && name[1] == 'z');
3958 strncpy(&uncompressed_name[1], &name[2], len - 2);
3959 uncompressed_name[len - 1] = '\0';
3961 return uncompressed_name;
3967 // Check if a comdat group or .gnu.linkonce section with the given
3968 // NAME is selected for the link. If there is already a section,
3969 // *KEPT_SECTION is set to point to the existing section and the
3970 // function returns false. Otherwise, OBJECT, SHNDX, IS_COMDAT, and
3971 // IS_GROUP_NAME are recorded for this NAME in the layout object,
3972 // *KEPT_SECTION is set to the internal copy and the function returns
3976 Layout::find_or_add_kept_section(const std::string& name,
3981 Kept_section** kept_section)
3983 // It's normal to see a couple of entries here, for the x86 thunk
3984 // sections. If we see more than a few, we're linking a C++
3985 // program, and we resize to get more space to minimize rehashing.
3986 if (this->signatures_.size() > 4
3987 && !this->resized_signatures_)
3989 reserve_unordered_map(&this->signatures_,
3990 this->number_of_input_files_ * 64);
3991 this->resized_signatures_ = true;
3994 Kept_section candidate;
3995 std::pair<Signatures::iterator, bool> ins =
3996 this->signatures_.insert(std::make_pair(name, candidate));
3998 if (kept_section != NULL)
3999 *kept_section = &ins.first->second;
4002 // This is the first time we've seen this signature.
4003 ins.first->second.set_object(object);
4004 ins.first->second.set_shndx(shndx);
4006 ins.first->second.set_is_comdat();
4008 ins.first->second.set_is_group_name();
4012 // We have already seen this signature.
4014 if (ins.first->second.is_group_name())
4016 // We've already seen a real section group with this signature.
4017 // If the kept group is from a plugin object, and we're in the
4018 // replacement phase, accept the new one as a replacement.
4019 if (ins.first->second.object() == NULL
4020 && parameters->options().plugins()->in_replacement_phase())
4022 ins.first->second.set_object(object);
4023 ins.first->second.set_shndx(shndx);
4028 else if (is_group_name)
4030 // This is a real section group, and we've already seen a
4031 // linkonce section with this signature. Record that we've seen
4032 // a section group, and don't include this section group.
4033 ins.first->second.set_is_group_name();
4038 // We've already seen a linkonce section and this is a linkonce
4039 // section. These don't block each other--this may be the same
4040 // symbol name with different section types.
4045 // Store the allocated sections into the section list.
4048 Layout::get_allocated_sections(Section_list* section_list) const
4050 for (Section_list::const_iterator p = this->section_list_.begin();
4051 p != this->section_list_.end();
4053 if (((*p)->flags() & elfcpp::SHF_ALLOC) != 0)
4054 section_list->push_back(*p);
4057 // Create an output segment.
4060 Layout::make_output_segment(elfcpp::Elf_Word type, elfcpp::Elf_Word flags)
4062 gold_assert(!parameters->options().relocatable());
4063 Output_segment* oseg = new Output_segment(type, flags);
4064 this->segment_list_.push_back(oseg);
4066 if (type == elfcpp::PT_TLS)
4067 this->tls_segment_ = oseg;
4068 else if (type == elfcpp::PT_GNU_RELRO)
4069 this->relro_segment_ = oseg;
4074 // Write out the Output_sections. Most won't have anything to write,
4075 // since most of the data will come from input sections which are
4076 // handled elsewhere. But some Output_sections do have Output_data.
4079 Layout::write_output_sections(Output_file* of) const
4081 for (Section_list::const_iterator p = this->section_list_.begin();
4082 p != this->section_list_.end();
4085 if (!(*p)->after_input_sections())
4090 // Write out data not associated with a section or the symbol table.
4093 Layout::write_data(const Symbol_table* symtab, Output_file* of) const
4095 if (!parameters->options().strip_all())
4097 const Output_section* symtab_section = this->symtab_section_;
4098 for (Section_list::const_iterator p = this->section_list_.begin();
4099 p != this->section_list_.end();
4102 if ((*p)->needs_symtab_index())
4104 gold_assert(symtab_section != NULL);
4105 unsigned int index = (*p)->symtab_index();
4106 gold_assert(index > 0 && index != -1U);
4107 off_t off = (symtab_section->offset()
4108 + index * symtab_section->entsize());
4109 symtab->write_section_symbol(*p, this->symtab_xindex_, of, off);
4114 const Output_section* dynsym_section = this->dynsym_section_;
4115 for (Section_list::const_iterator p = this->section_list_.begin();
4116 p != this->section_list_.end();
4119 if ((*p)->needs_dynsym_index())
4121 gold_assert(dynsym_section != NULL);
4122 unsigned int index = (*p)->dynsym_index();
4123 gold_assert(index > 0 && index != -1U);
4124 off_t off = (dynsym_section->offset()
4125 + index * dynsym_section->entsize());
4126 symtab->write_section_symbol(*p, this->dynsym_xindex_, of, off);
4130 // Write out the Output_data which are not in an Output_section.
4131 for (Data_list::const_iterator p = this->special_output_list_.begin();
4132 p != this->special_output_list_.end();
4137 // Write out the Output_sections which can only be written after the
4138 // input sections are complete.
4141 Layout::write_sections_after_input_sections(Output_file* of)
4143 // Determine the final section offsets, and thus the final output
4144 // file size. Note we finalize the .shstrab last, to allow the
4145 // after_input_section sections to modify their section-names before
4147 if (this->any_postprocessing_sections_)
4149 off_t off = this->output_file_size_;
4150 off = this->set_section_offsets(off, POSTPROCESSING_SECTIONS_PASS);
4152 // Now that we've finalized the names, we can finalize the shstrab.
4154 this->set_section_offsets(off,
4155 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS);
4157 if (off > this->output_file_size_)
4160 this->output_file_size_ = off;
4164 for (Section_list::const_iterator p = this->section_list_.begin();
4165 p != this->section_list_.end();
4168 if ((*p)->after_input_sections())
4172 this->section_headers_->write(of);
4175 // If the build ID requires computing a checksum, do so here, and
4176 // write it out. We compute a checksum over the entire file because
4177 // that is simplest.
4180 Layout::write_build_id(Output_file* of) const
4182 if (this->build_id_note_ == NULL)
4185 const unsigned char* iv = of->get_input_view(0, this->output_file_size_);
4187 unsigned char* ov = of->get_output_view(this->build_id_note_->offset(),
4188 this->build_id_note_->data_size());
4190 const char* style = parameters->options().build_id();
4191 if (strcmp(style, "sha1") == 0)
4194 sha1_init_ctx(&ctx);
4195 sha1_process_bytes(iv, this->output_file_size_, &ctx);
4196 sha1_finish_ctx(&ctx, ov);
4198 else if (strcmp(style, "md5") == 0)
4202 md5_process_bytes(iv, this->output_file_size_, &ctx);
4203 md5_finish_ctx(&ctx, ov);
4208 of->write_output_view(this->build_id_note_->offset(),
4209 this->build_id_note_->data_size(),
4212 of->free_input_view(0, this->output_file_size_, iv);
4215 // Write out a binary file. This is called after the link is
4216 // complete. IN is the temporary output file we used to generate the
4217 // ELF code. We simply walk through the segments, read them from
4218 // their file offset in IN, and write them to their load address in
4219 // the output file. FIXME: with a bit more work, we could support
4220 // S-records and/or Intel hex format here.
4223 Layout::write_binary(Output_file* in) const
4225 gold_assert(parameters->options().oformat_enum()
4226 == General_options::OBJECT_FORMAT_BINARY);
4228 // Get the size of the binary file.
4229 uint64_t max_load_address = 0;
4230 for (Segment_list::const_iterator p = this->segment_list_.begin();
4231 p != this->segment_list_.end();
4234 if ((*p)->type() == elfcpp::PT_LOAD && (*p)->filesz() > 0)
4236 uint64_t max_paddr = (*p)->paddr() + (*p)->filesz();
4237 if (max_paddr > max_load_address)
4238 max_load_address = max_paddr;
4242 Output_file out(parameters->options().output_file_name());
4243 out.open(max_load_address);
4245 for (Segment_list::const_iterator p = this->segment_list_.begin();
4246 p != this->segment_list_.end();
4249 if ((*p)->type() == elfcpp::PT_LOAD && (*p)->filesz() > 0)
4251 const unsigned char* vin = in->get_input_view((*p)->offset(),
4253 unsigned char* vout = out.get_output_view((*p)->paddr(),
4255 memcpy(vout, vin, (*p)->filesz());
4256 out.write_output_view((*p)->paddr(), (*p)->filesz(), vout);
4257 in->free_input_view((*p)->offset(), (*p)->filesz(), vin);
4264 // Print the output sections to the map file.
4267 Layout::print_to_mapfile(Mapfile* mapfile) const
4269 for (Segment_list::const_iterator p = this->segment_list_.begin();
4270 p != this->segment_list_.end();
4272 (*p)->print_sections_to_mapfile(mapfile);
4275 // Print statistical information to stderr. This is used for --stats.
4278 Layout::print_stats() const
4280 this->namepool_.print_stats("section name pool");
4281 this->sympool_.print_stats("output symbol name pool");
4282 this->dynpool_.print_stats("dynamic name pool");
4284 for (Section_list::const_iterator p = this->section_list_.begin();
4285 p != this->section_list_.end();
4287 (*p)->print_merge_stats();
4290 // Write_sections_task methods.
4292 // We can always run this task.
4295 Write_sections_task::is_runnable()
4300 // We need to unlock both OUTPUT_SECTIONS_BLOCKER and FINAL_BLOCKER
4304 Write_sections_task::locks(Task_locker* tl)
4306 tl->add(this, this->output_sections_blocker_);
4307 tl->add(this, this->final_blocker_);
4310 // Run the task--write out the data.
4313 Write_sections_task::run(Workqueue*)
4315 this->layout_->write_output_sections(this->of_);
4318 // Write_data_task methods.
4320 // We can always run this task.
4323 Write_data_task::is_runnable()
4328 // We need to unlock FINAL_BLOCKER when finished.
4331 Write_data_task::locks(Task_locker* tl)
4333 tl->add(this, this->final_blocker_);
4336 // Run the task--write out the data.
4339 Write_data_task::run(Workqueue*)
4341 this->layout_->write_data(this->symtab_, this->of_);
4344 // Write_symbols_task methods.
4346 // We can always run this task.
4349 Write_symbols_task::is_runnable()
4354 // We need to unlock FINAL_BLOCKER when finished.
4357 Write_symbols_task::locks(Task_locker* tl)
4359 tl->add(this, this->final_blocker_);
4362 // Run the task--write out the symbols.
4365 Write_symbols_task::run(Workqueue*)
4367 this->symtab_->write_globals(this->sympool_, this->dynpool_,
4368 this->layout_->symtab_xindex(),
4369 this->layout_->dynsym_xindex(), this->of_);
4372 // Write_after_input_sections_task methods.
4374 // We can only run this task after the input sections have completed.
4377 Write_after_input_sections_task::is_runnable()
4379 if (this->input_sections_blocker_->is_blocked())
4380 return this->input_sections_blocker_;
4384 // We need to unlock FINAL_BLOCKER when finished.
4387 Write_after_input_sections_task::locks(Task_locker* tl)
4389 tl->add(this, this->final_blocker_);
4395 Write_after_input_sections_task::run(Workqueue*)
4397 this->layout_->write_sections_after_input_sections(this->of_);
4400 // Close_task_runner methods.
4402 // Run the task--close the file.
4405 Close_task_runner::run(Workqueue*, const Task*)
4407 // If we need to compute a checksum for the BUILD if, we do so here.
4408 this->layout_->write_build_id(this->of_);
4410 // If we've been asked to create a binary file, we do so here.
4411 if (this->options_->oformat_enum() != General_options::OBJECT_FORMAT_ELF)
4412 this->layout_->write_binary(this->of_);
4417 // Instantiate the templates we need. We could use the configure
4418 // script to restrict this to only the ones for implemented targets.
4420 #ifdef HAVE_TARGET_32_LITTLE
4423 Layout::layout<32, false>(Sized_relobj<32, false>* object, unsigned int shndx,
4425 const elfcpp::Shdr<32, false>& shdr,
4426 unsigned int, unsigned int, off_t*);
4429 #ifdef HAVE_TARGET_32_BIG
4432 Layout::layout<32, true>(Sized_relobj<32, true>* object, unsigned int shndx,
4434 const elfcpp::Shdr<32, true>& shdr,
4435 unsigned int, unsigned int, off_t*);
4438 #ifdef HAVE_TARGET_64_LITTLE
4441 Layout::layout<64, false>(Sized_relobj<64, false>* object, unsigned int shndx,
4443 const elfcpp::Shdr<64, false>& shdr,
4444 unsigned int, unsigned int, off_t*);
4447 #ifdef HAVE_TARGET_64_BIG
4450 Layout::layout<64, true>(Sized_relobj<64, true>* object, unsigned int shndx,
4452 const elfcpp::Shdr<64, true>& shdr,
4453 unsigned int, unsigned int, off_t*);
4456 #ifdef HAVE_TARGET_32_LITTLE
4459 Layout::layout_reloc<32, false>(Sized_relobj<32, false>* object,
4460 unsigned int reloc_shndx,
4461 const elfcpp::Shdr<32, false>& shdr,
4462 Output_section* data_section,
4463 Relocatable_relocs* rr);
4466 #ifdef HAVE_TARGET_32_BIG
4469 Layout::layout_reloc<32, true>(Sized_relobj<32, true>* object,
4470 unsigned int reloc_shndx,
4471 const elfcpp::Shdr<32, true>& shdr,
4472 Output_section* data_section,
4473 Relocatable_relocs* rr);
4476 #ifdef HAVE_TARGET_64_LITTLE
4479 Layout::layout_reloc<64, false>(Sized_relobj<64, false>* object,
4480 unsigned int reloc_shndx,
4481 const elfcpp::Shdr<64, false>& shdr,
4482 Output_section* data_section,
4483 Relocatable_relocs* rr);
4486 #ifdef HAVE_TARGET_64_BIG
4489 Layout::layout_reloc<64, true>(Sized_relobj<64, true>* object,
4490 unsigned int reloc_shndx,
4491 const elfcpp::Shdr<64, true>& shdr,
4492 Output_section* data_section,
4493 Relocatable_relocs* rr);
4496 #ifdef HAVE_TARGET_32_LITTLE
4499 Layout::layout_group<32, false>(Symbol_table* symtab,
4500 Sized_relobj<32, false>* object,
4502 const char* group_section_name,
4503 const char* signature,
4504 const elfcpp::Shdr<32, false>& shdr,
4505 elfcpp::Elf_Word flags,
4506 std::vector<unsigned int>* shndxes);
4509 #ifdef HAVE_TARGET_32_BIG
4512 Layout::layout_group<32, true>(Symbol_table* symtab,
4513 Sized_relobj<32, true>* object,
4515 const char* group_section_name,
4516 const char* signature,
4517 const elfcpp::Shdr<32, true>& shdr,
4518 elfcpp::Elf_Word flags,
4519 std::vector<unsigned int>* shndxes);
4522 #ifdef HAVE_TARGET_64_LITTLE
4525 Layout::layout_group<64, false>(Symbol_table* symtab,
4526 Sized_relobj<64, false>* object,
4528 const char* group_section_name,
4529 const char* signature,
4530 const elfcpp::Shdr<64, false>& shdr,
4531 elfcpp::Elf_Word flags,
4532 std::vector<unsigned int>* shndxes);
4535 #ifdef HAVE_TARGET_64_BIG
4538 Layout::layout_group<64, true>(Symbol_table* symtab,
4539 Sized_relobj<64, true>* object,
4541 const char* group_section_name,
4542 const char* signature,
4543 const elfcpp::Shdr<64, true>& shdr,
4544 elfcpp::Elf_Word flags,
4545 std::vector<unsigned int>* shndxes);
4548 #ifdef HAVE_TARGET_32_LITTLE
4551 Layout::layout_eh_frame<32, false>(Sized_relobj<32, false>* object,
4552 const unsigned char* symbols,
4554 const unsigned char* symbol_names,
4555 off_t symbol_names_size,
4557 const elfcpp::Shdr<32, false>& shdr,
4558 unsigned int reloc_shndx,
4559 unsigned int reloc_type,
4563 #ifdef HAVE_TARGET_32_BIG
4566 Layout::layout_eh_frame<32, true>(Sized_relobj<32, true>* object,
4567 const unsigned char* symbols,
4569 const unsigned char* symbol_names,
4570 off_t symbol_names_size,
4572 const elfcpp::Shdr<32, true>& shdr,
4573 unsigned int reloc_shndx,
4574 unsigned int reloc_type,
4578 #ifdef HAVE_TARGET_64_LITTLE
4581 Layout::layout_eh_frame<64, false>(Sized_relobj<64, false>* object,
4582 const unsigned char* symbols,
4584 const unsigned char* symbol_names,
4585 off_t symbol_names_size,
4587 const elfcpp::Shdr<64, false>& shdr,
4588 unsigned int reloc_shndx,
4589 unsigned int reloc_type,
4593 #ifdef HAVE_TARGET_64_BIG
4596 Layout::layout_eh_frame<64, true>(Sized_relobj<64, true>* object,
4597 const unsigned char* symbols,
4599 const unsigned char* symbol_names,
4600 off_t symbol_names_size,
4602 const elfcpp::Shdr<64, true>& shdr,
4603 unsigned int reloc_shndx,
4604 unsigned int reloc_type,
4608 } // End namespace gold.