1 // layout.cc -- lay out output file sections for gold
3 // Copyright (C) 2006-2016 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"
42 #include "parameters.h"
46 #include "script-sections.h"
51 #include "gdb-index.h"
52 #include "compressed_output.h"
53 #include "reduced_debug_output.h"
56 #include "descriptors.h"
58 #include "incremental.h"
66 // The total number of free lists used.
67 unsigned int Free_list::num_lists = 0;
68 // The total number of free list nodes used.
69 unsigned int Free_list::num_nodes = 0;
70 // The total number of calls to Free_list::remove.
71 unsigned int Free_list::num_removes = 0;
72 // The total number of nodes visited during calls to Free_list::remove.
73 unsigned int Free_list::num_remove_visits = 0;
74 // The total number of calls to Free_list::allocate.
75 unsigned int Free_list::num_allocates = 0;
76 // The total number of nodes visited during calls to Free_list::allocate.
77 unsigned int Free_list::num_allocate_visits = 0;
79 // Initialize the free list. Creates a single free list node that
80 // describes the entire region of length LEN. If EXTEND is true,
81 // allocate() is allowed to extend the region beyond its initial
85 Free_list::init(off_t len, bool extend)
87 this->list_.push_front(Free_list_node(0, len));
88 this->last_remove_ = this->list_.begin();
89 this->extend_ = extend;
91 ++Free_list::num_lists;
92 ++Free_list::num_nodes;
95 // Remove a chunk from the free list. Because we start with a single
96 // node that covers the entire section, and remove chunks from it one
97 // at a time, we do not need to coalesce chunks or handle cases that
98 // span more than one free node. We expect to remove chunks from the
99 // free list in order, and we expect to have only a few chunks of free
100 // space left (corresponding to files that have changed since the last
101 // incremental link), so a simple linear list should provide sufficient
105 Free_list::remove(off_t start, off_t end)
109 gold_assert(start < end);
111 ++Free_list::num_removes;
113 Iterator p = this->last_remove_;
114 if (p->start_ > start)
115 p = this->list_.begin();
117 for (; p != this->list_.end(); ++p)
119 ++Free_list::num_remove_visits;
120 // Find a node that wholly contains the indicated region.
121 if (p->start_ <= start && p->end_ >= end)
123 // Case 1: the indicated region spans the whole node.
124 // Add some fuzz to avoid creating tiny free chunks.
125 if (p->start_ + 3 >= start && p->end_ <= end + 3)
126 p = this->list_.erase(p);
127 // Case 2: remove a chunk from the start of the node.
128 else if (p->start_ + 3 >= start)
130 // Case 3: remove a chunk from the end of the node.
131 else if (p->end_ <= end + 3)
133 // Case 4: remove a chunk from the middle, and split
134 // the node into two.
137 Free_list_node newnode(p->start_, start);
139 this->list_.insert(p, newnode);
140 ++Free_list::num_nodes;
142 this->last_remove_ = p;
147 // Did not find a node containing the given chunk. This could happen
148 // because a small chunk was already removed due to the fuzz.
149 gold_debug(DEBUG_INCREMENTAL,
150 "Free_list::remove(%d,%d) not found",
151 static_cast<int>(start), static_cast<int>(end));
154 // Allocate a chunk of size LEN from the free list. Returns -1ULL
155 // if a sufficiently large chunk of free space is not found.
156 // We use a simple first-fit algorithm.
159 Free_list::allocate(off_t len, uint64_t align, off_t minoff)
161 gold_debug(DEBUG_INCREMENTAL,
162 "Free_list::allocate(%08lx, %d, %08lx)",
163 static_cast<long>(len), static_cast<int>(align),
164 static_cast<long>(minoff));
166 return align_address(minoff, align);
168 ++Free_list::num_allocates;
170 // We usually want to drop free chunks smaller than 4 bytes.
171 // If we need to guarantee a minimum hole size, though, we need
172 // to keep track of all free chunks.
173 const int fuzz = this->min_hole_ > 0 ? 0 : 3;
175 for (Iterator p = this->list_.begin(); p != this->list_.end(); ++p)
177 ++Free_list::num_allocate_visits;
178 off_t start = p->start_ > minoff ? p->start_ : minoff;
179 start = align_address(start, align);
180 off_t end = start + len;
181 if (end > p->end_ && p->end_ == this->length_ && this->extend_)
186 if (end == p->end_ || (end <= p->end_ - this->min_hole_))
188 if (p->start_ + fuzz >= start && p->end_ <= end + fuzz)
189 this->list_.erase(p);
190 else if (p->start_ + fuzz >= start)
192 else if (p->end_ <= end + fuzz)
196 Free_list_node newnode(p->start_, start);
198 this->list_.insert(p, newnode);
199 ++Free_list::num_nodes;
206 off_t start = align_address(this->length_, align);
207 this->length_ = start + len;
213 // Dump the free list (for debugging).
217 gold_info("Free list:\n start end length\n");
218 for (Iterator p = this->list_.begin(); p != this->list_.end(); ++p)
219 gold_info(" %08lx %08lx %08lx", static_cast<long>(p->start_),
220 static_cast<long>(p->end_),
221 static_cast<long>(p->end_ - p->start_));
224 // Print the statistics for the free lists.
226 Free_list::print_stats()
228 fprintf(stderr, _("%s: total free lists: %u\n"),
229 program_name, Free_list::num_lists);
230 fprintf(stderr, _("%s: total free list nodes: %u\n"),
231 program_name, Free_list::num_nodes);
232 fprintf(stderr, _("%s: calls to Free_list::remove: %u\n"),
233 program_name, Free_list::num_removes);
234 fprintf(stderr, _("%s: nodes visited: %u\n"),
235 program_name, Free_list::num_remove_visits);
236 fprintf(stderr, _("%s: calls to Free_list::allocate: %u\n"),
237 program_name, Free_list::num_allocates);
238 fprintf(stderr, _("%s: nodes visited: %u\n"),
239 program_name, Free_list::num_allocate_visits);
242 // A Hash_task computes the MD5 checksum of an array of char.
244 class Hash_task : public Task
247 Hash_task(Output_file* of,
251 Task_token* final_blocker)
252 : of_(of), offset_(offset), size_(size), dst_(dst),
253 final_blocker_(final_blocker)
259 const unsigned char* iv =
260 this->of_->get_input_view(this->offset_, this->size_);
261 md5_buffer(reinterpret_cast<const char*>(iv), this->size_, this->dst_);
262 this->of_->free_input_view(this->offset_, this->size_, iv);
269 // Unblock FINAL_BLOCKER_ when done.
271 locks(Task_locker* tl)
272 { tl->add(this, this->final_blocker_); }
276 { return "Hash_task"; }
280 const size_t offset_;
282 unsigned char* const dst_;
283 Task_token* const final_blocker_;
286 // Layout::Relaxation_debug_check methods.
288 // Check that sections and special data are in reset states.
289 // We do not save states for Output_sections and special Output_data.
290 // So we check that they have not assigned any addresses or offsets.
291 // clean_up_after_relaxation simply resets their addresses and offsets.
293 Layout::Relaxation_debug_check::check_output_data_for_reset_values(
294 const Layout::Section_list& sections,
295 const Layout::Data_list& special_outputs,
296 const Layout::Data_list& relax_outputs)
298 for(Layout::Section_list::const_iterator p = sections.begin();
301 gold_assert((*p)->address_and_file_offset_have_reset_values());
303 for(Layout::Data_list::const_iterator p = special_outputs.begin();
304 p != special_outputs.end();
306 gold_assert((*p)->address_and_file_offset_have_reset_values());
308 gold_assert(relax_outputs.empty());
311 // Save information of SECTIONS for checking later.
314 Layout::Relaxation_debug_check::read_sections(
315 const Layout::Section_list& sections)
317 for(Layout::Section_list::const_iterator p = sections.begin();
321 Output_section* os = *p;
323 info.output_section = os;
324 info.address = os->is_address_valid() ? os->address() : 0;
325 info.data_size = os->is_data_size_valid() ? os->data_size() : -1;
326 info.offset = os->is_offset_valid()? os->offset() : -1 ;
327 this->section_infos_.push_back(info);
331 // Verify SECTIONS using previously recorded information.
334 Layout::Relaxation_debug_check::verify_sections(
335 const Layout::Section_list& sections)
338 for(Layout::Section_list::const_iterator p = sections.begin();
342 Output_section* os = *p;
343 uint64_t address = os->is_address_valid() ? os->address() : 0;
344 off_t data_size = os->is_data_size_valid() ? os->data_size() : -1;
345 off_t offset = os->is_offset_valid()? os->offset() : -1 ;
347 if (i >= this->section_infos_.size())
349 gold_fatal("Section_info of %s missing.\n", os->name());
351 const Section_info& info = this->section_infos_[i];
352 if (os != info.output_section)
353 gold_fatal("Section order changed. Expecting %s but see %s\n",
354 info.output_section->name(), os->name());
355 if (address != info.address
356 || data_size != info.data_size
357 || offset != info.offset)
358 gold_fatal("Section %s changed.\n", os->name());
362 // Layout_task_runner methods.
364 // Lay out the sections. This is called after all the input objects
368 Layout_task_runner::run(Workqueue* workqueue, const Task* task)
370 // See if any of the input definitions violate the One Definition Rule.
371 // TODO: if this is too slow, do this as a task, rather than inline.
372 this->symtab_->detect_odr_violations(task, this->options_.output_file_name());
374 Layout* layout = this->layout_;
375 off_t file_size = layout->finalize(this->input_objects_,
380 // Now we know the final size of the output file and we know where
381 // each piece of information goes.
383 if (this->mapfile_ != NULL)
385 this->mapfile_->print_discarded_sections(this->input_objects_);
386 layout->print_to_mapfile(this->mapfile_);
390 if (layout->incremental_base() == NULL)
392 of = new Output_file(parameters->options().output_file_name());
393 if (this->options_.oformat_enum() != General_options::OBJECT_FORMAT_ELF)
394 of->set_is_temporary();
399 of = layout->incremental_base()->output_file();
401 // Apply the incremental relocations for symbols whose values
402 // have changed. We do this before we resize the file and start
403 // writing anything else to it, so that we can read the old
404 // incremental information from the file before (possibly)
406 if (parameters->incremental_update())
407 layout->incremental_base()->apply_incremental_relocs(this->symtab_,
411 of->resize(file_size);
414 // Queue up the final set of tasks.
415 gold::queue_final_tasks(this->options_, this->input_objects_,
416 this->symtab_, layout, workqueue, of);
421 Layout::Layout(int number_of_input_files, Script_options* script_options)
422 : number_of_input_files_(number_of_input_files),
423 script_options_(script_options),
431 unattached_section_list_(),
432 special_output_list_(),
433 relax_output_list_(),
434 section_headers_(NULL),
436 relro_segment_(NULL),
437 interp_segment_(NULL),
439 symtab_section_(NULL),
440 symtab_xindex_(NULL),
441 dynsym_section_(NULL),
442 dynsym_xindex_(NULL),
443 dynamic_section_(NULL),
444 dynamic_symbol_(NULL),
446 eh_frame_section_(NULL),
447 eh_frame_data_(NULL),
448 added_eh_frame_data_(false),
449 eh_frame_hdr_section_(NULL),
450 gdb_index_data_(NULL),
451 build_id_note_(NULL),
455 output_file_size_(-1),
456 have_added_input_section_(false),
457 sections_are_attached_(false),
458 input_requires_executable_stack_(false),
459 input_with_gnu_stack_note_(false),
460 input_without_gnu_stack_note_(false),
461 has_static_tls_(false),
462 any_postprocessing_sections_(false),
463 resized_signatures_(false),
464 have_stabstr_section_(false),
465 section_ordering_specified_(false),
466 unique_segment_for_sections_specified_(false),
467 incremental_inputs_(NULL),
468 record_output_section_data_from_script_(false),
469 script_output_section_data_list_(),
470 segment_states_(NULL),
471 relaxation_debug_check_(NULL),
472 section_order_map_(),
473 section_segment_map_(),
474 input_section_position_(),
475 input_section_glob_(),
476 incremental_base_(NULL),
479 // Make space for more than enough segments for a typical file.
480 // This is just for efficiency--it's OK if we wind up needing more.
481 this->segment_list_.reserve(12);
483 // We expect two unattached Output_data objects: the file header and
484 // the segment headers.
485 this->special_output_list_.reserve(2);
487 // Initialize structure needed for an incremental build.
488 if (parameters->incremental())
489 this->incremental_inputs_ = new Incremental_inputs;
491 // The section name pool is worth optimizing in all cases, because
492 // it is small, but there are often overlaps due to .rel sections.
493 this->namepool_.set_optimize();
496 // For incremental links, record the base file to be modified.
499 Layout::set_incremental_base(Incremental_binary* base)
501 this->incremental_base_ = base;
502 this->free_list_.init(base->output_file()->filesize(), true);
505 // Hash a key we use to look up an output section mapping.
508 Layout::Hash_key::operator()(const Layout::Key& k) const
510 return k.first + k.second.first + k.second.second;
513 // These are the debug sections that are actually used by gdb.
514 // Currently, we've checked versions of gdb up to and including 7.4.
515 // We only check the part of the name that follows ".debug_" or
518 static const char* gdb_sections[] =
521 "addr", // Fission extension
522 // "aranges", // not used by gdb as of 7.4
531 // "pubnames", // not used by gdb as of 7.4
532 // "pubtypes", // not used by gdb as of 7.4
533 // "gnu_pubnames", // Fission extension
534 // "gnu_pubtypes", // Fission extension
540 // This is the minimum set of sections needed for line numbers.
542 static const char* lines_only_debug_sections[] =
545 // "addr", // Fission extension
546 // "aranges", // not used by gdb as of 7.4
555 // "pubnames", // not used by gdb as of 7.4
556 // "pubtypes", // not used by gdb as of 7.4
557 // "gnu_pubnames", // Fission extension
558 // "gnu_pubtypes", // Fission extension
561 "str_offsets", // Fission extension
564 // These sections are the DWARF fast-lookup tables, and are not needed
565 // when building a .gdb_index section.
567 static const char* gdb_fast_lookup_sections[] =
576 // Returns whether the given debug section is in the list of
577 // debug-sections-used-by-some-version-of-gdb. SUFFIX is the
578 // portion of the name following ".debug_" or ".zdebug_".
581 is_gdb_debug_section(const char* suffix)
583 // We can do this faster: binary search or a hashtable. But why bother?
584 for (size_t i = 0; i < sizeof(gdb_sections)/sizeof(*gdb_sections); ++i)
585 if (strcmp(suffix, gdb_sections[i]) == 0)
590 // Returns whether the given section is needed for lines-only debugging.
593 is_lines_only_debug_section(const char* suffix)
595 // We can do this faster: binary search or a hashtable. But why bother?
597 i < sizeof(lines_only_debug_sections)/sizeof(*lines_only_debug_sections);
599 if (strcmp(suffix, lines_only_debug_sections[i]) == 0)
604 // Returns whether the given section is a fast-lookup section that
605 // will not be needed when building a .gdb_index section.
608 is_gdb_fast_lookup_section(const char* suffix)
610 // We can do this faster: binary search or a hashtable. But why bother?
612 i < sizeof(gdb_fast_lookup_sections)/sizeof(*gdb_fast_lookup_sections);
614 if (strcmp(suffix, gdb_fast_lookup_sections[i]) == 0)
619 // Sometimes we compress sections. This is typically done for
620 // sections that are not part of normal program execution (such as
621 // .debug_* sections), and where the readers of these sections know
622 // how to deal with compressed sections. This routine doesn't say for
623 // certain whether we'll compress -- it depends on commandline options
624 // as well -- just whether this section is a candidate for compression.
625 // (The Output_compressed_section class decides whether to compress
626 // a given section, and picks the name of the compressed section.)
629 is_compressible_debug_section(const char* secname)
631 return (is_prefix_of(".debug", secname));
634 // We may see compressed debug sections in input files. Return TRUE
635 // if this is the name of a compressed debug section.
638 is_compressed_debug_section(const char* secname)
640 return (is_prefix_of(".zdebug", secname));
644 corresponding_uncompressed_section_name(std::string secname)
646 gold_assert(secname[0] == '.' && secname[1] == 'z');
647 std::string ret(".");
648 ret.append(secname, 2, std::string::npos);
652 // Whether to include this section in the link.
654 template<int size, bool big_endian>
656 Layout::include_section(Sized_relobj_file<size, big_endian>*, const char* name,
657 const elfcpp::Shdr<size, big_endian>& shdr)
659 if (!parameters->options().relocatable()
660 && (shdr.get_sh_flags() & elfcpp::SHF_EXCLUDE))
663 elfcpp::Elf_Word sh_type = shdr.get_sh_type();
665 if ((sh_type >= elfcpp::SHT_LOOS && sh_type <= elfcpp::SHT_HIOS)
666 || (sh_type >= elfcpp::SHT_LOPROC && sh_type <= elfcpp::SHT_HIPROC))
667 return parameters->target().should_include_section(sh_type);
671 case elfcpp::SHT_NULL:
672 case elfcpp::SHT_SYMTAB:
673 case elfcpp::SHT_DYNSYM:
674 case elfcpp::SHT_HASH:
675 case elfcpp::SHT_DYNAMIC:
676 case elfcpp::SHT_SYMTAB_SHNDX:
679 case elfcpp::SHT_STRTAB:
680 // Discard the sections which have special meanings in the ELF
681 // ABI. Keep others (e.g., .stabstr). We could also do this by
682 // checking the sh_link fields of the appropriate sections.
683 return (strcmp(name, ".dynstr") != 0
684 && strcmp(name, ".strtab") != 0
685 && strcmp(name, ".shstrtab") != 0);
687 case elfcpp::SHT_RELA:
688 case elfcpp::SHT_REL:
689 case elfcpp::SHT_GROUP:
690 // If we are emitting relocations these should be handled
692 gold_assert(!parameters->options().relocatable());
695 case elfcpp::SHT_PROGBITS:
696 if (parameters->options().strip_debug()
697 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
699 if (is_debug_info_section(name))
702 if (parameters->options().strip_debug_non_line()
703 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
705 // Debugging sections can only be recognized by name.
706 if (is_prefix_of(".debug_", name)
707 && !is_lines_only_debug_section(name + 7))
709 if (is_prefix_of(".zdebug_", name)
710 && !is_lines_only_debug_section(name + 8))
713 if (parameters->options().strip_debug_gdb()
714 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
716 // Debugging sections can only be recognized by name.
717 if (is_prefix_of(".debug_", name)
718 && !is_gdb_debug_section(name + 7))
720 if (is_prefix_of(".zdebug_", name)
721 && !is_gdb_debug_section(name + 8))
724 if (parameters->options().gdb_index()
725 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
727 // When building .gdb_index, we can strip .debug_pubnames,
728 // .debug_pubtypes, and .debug_aranges sections.
729 if (is_prefix_of(".debug_", name)
730 && is_gdb_fast_lookup_section(name + 7))
732 if (is_prefix_of(".zdebug_", name)
733 && is_gdb_fast_lookup_section(name + 8))
736 if (parameters->options().strip_lto_sections()
737 && !parameters->options().relocatable()
738 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
740 // Ignore LTO sections containing intermediate code.
741 if (is_prefix_of(".gnu.lto_", name))
744 // The GNU linker strips .gnu_debuglink sections, so we do too.
745 // This is a feature used to keep debugging information in
747 if (strcmp(name, ".gnu_debuglink") == 0)
756 // Return an output section named NAME, or NULL if there is none.
759 Layout::find_output_section(const char* name) const
761 for (Section_list::const_iterator p = this->section_list_.begin();
762 p != this->section_list_.end();
764 if (strcmp((*p)->name(), name) == 0)
769 // Return an output segment of type TYPE, with segment flags SET set
770 // and segment flags CLEAR clear. Return NULL if there is none.
773 Layout::find_output_segment(elfcpp::PT type, elfcpp::Elf_Word set,
774 elfcpp::Elf_Word clear) const
776 for (Segment_list::const_iterator p = this->segment_list_.begin();
777 p != this->segment_list_.end();
779 if (static_cast<elfcpp::PT>((*p)->type()) == type
780 && ((*p)->flags() & set) == set
781 && ((*p)->flags() & clear) == 0)
786 // When we put a .ctors or .dtors section with more than one word into
787 // a .init_array or .fini_array section, we need to reverse the words
788 // in the .ctors/.dtors section. This is because .init_array executes
789 // constructors front to back, where .ctors executes them back to
790 // front, and vice-versa for .fini_array/.dtors. Although we do want
791 // to remap .ctors/.dtors into .init_array/.fini_array because it can
792 // be more efficient, we don't want to change the order in which
793 // constructors/destructors are run. This set just keeps track of
794 // these sections which need to be reversed. It is only changed by
795 // Layout::layout. It should be a private member of Layout, but that
796 // would require layout.h to #include object.h to get the definition
798 static Unordered_set<Section_id, Section_id_hash> ctors_sections_in_init_array;
800 // Return whether OBJECT/SHNDX is a .ctors/.dtors section mapped to a
801 // .init_array/.fini_array section.
804 Layout::is_ctors_in_init_array(Relobj* relobj, unsigned int shndx) const
806 return (ctors_sections_in_init_array.find(Section_id(relobj, shndx))
807 != ctors_sections_in_init_array.end());
810 // Return the output section to use for section NAME with type TYPE
811 // and section flags FLAGS. NAME must be canonicalized in the string
812 // pool, and NAME_KEY is the key. ORDER is where this should appear
813 // in the output sections. IS_RELRO is true for a relro section.
816 Layout::get_output_section(const char* name, Stringpool::Key name_key,
817 elfcpp::Elf_Word type, elfcpp::Elf_Xword flags,
818 Output_section_order order, bool is_relro)
820 elfcpp::Elf_Word lookup_type = type;
822 // For lookup purposes, treat INIT_ARRAY, FINI_ARRAY, and
823 // PREINIT_ARRAY like PROGBITS. This ensures that we combine
824 // .init_array, .fini_array, and .preinit_array sections by name
825 // whatever their type in the input file. We do this because the
826 // types are not always right in the input files.
827 if (lookup_type == elfcpp::SHT_INIT_ARRAY
828 || lookup_type == elfcpp::SHT_FINI_ARRAY
829 || lookup_type == elfcpp::SHT_PREINIT_ARRAY)
830 lookup_type = elfcpp::SHT_PROGBITS;
832 elfcpp::Elf_Xword lookup_flags = flags;
834 // Ignoring SHF_WRITE and SHF_EXECINSTR here means that we combine
835 // read-write with read-only sections. Some other ELF linkers do
836 // not do this. FIXME: Perhaps there should be an option
838 lookup_flags &= ~(elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR);
840 const Key key(name_key, std::make_pair(lookup_type, lookup_flags));
841 const std::pair<Key, Output_section*> v(key, NULL);
842 std::pair<Section_name_map::iterator, bool> ins(
843 this->section_name_map_.insert(v));
846 return ins.first->second;
849 // This is the first time we've seen this name/type/flags
850 // combination. For compatibility with the GNU linker, we
851 // combine sections with contents and zero flags with sections
852 // with non-zero flags. This is a workaround for cases where
853 // assembler code forgets to set section flags. FIXME: Perhaps
854 // there should be an option to control this.
855 Output_section* os = NULL;
857 if (lookup_type == elfcpp::SHT_PROGBITS)
861 Output_section* same_name = this->find_output_section(name);
862 if (same_name != NULL
863 && (same_name->type() == elfcpp::SHT_PROGBITS
864 || same_name->type() == elfcpp::SHT_INIT_ARRAY
865 || same_name->type() == elfcpp::SHT_FINI_ARRAY
866 || same_name->type() == elfcpp::SHT_PREINIT_ARRAY)
867 && (same_name->flags() & elfcpp::SHF_TLS) == 0)
870 else if ((flags & elfcpp::SHF_TLS) == 0)
872 elfcpp::Elf_Xword zero_flags = 0;
873 const Key zero_key(name_key, std::make_pair(lookup_type,
875 Section_name_map::iterator p =
876 this->section_name_map_.find(zero_key);
877 if (p != this->section_name_map_.end())
883 os = this->make_output_section(name, type, flags, order, is_relro);
885 ins.first->second = os;
890 // Returns TRUE iff NAME (an input section from RELOBJ) will
891 // be mapped to an output section that should be KEPT.
894 Layout::keep_input_section(const Relobj* relobj, const char* name)
896 if (! this->script_options_->saw_sections_clause())
899 Script_sections* ss = this->script_options_->script_sections();
900 const char* file_name = relobj == NULL ? NULL : relobj->name().c_str();
901 Output_section** output_section_slot;
902 Script_sections::Section_type script_section_type;
905 name = ss->output_section_name(file_name, name, &output_section_slot,
906 &script_section_type, &keep, true);
907 return name != NULL && keep;
910 // Clear the input section flags that should not be copied to the
914 Layout::get_output_section_flags(elfcpp::Elf_Xword input_section_flags)
916 // Some flags in the input section should not be automatically
917 // copied to the output section.
918 input_section_flags &= ~ (elfcpp::SHF_INFO_LINK
920 | elfcpp::SHF_COMPRESSED
922 | elfcpp::SHF_STRINGS);
924 // We only clear the SHF_LINK_ORDER flag in for
925 // a non-relocatable link.
926 if (!parameters->options().relocatable())
927 input_section_flags &= ~elfcpp::SHF_LINK_ORDER;
929 return input_section_flags;
932 // Pick the output section to use for section NAME, in input file
933 // RELOBJ, with type TYPE and flags FLAGS. RELOBJ may be NULL for a
934 // linker created section. IS_INPUT_SECTION is true if we are
935 // choosing an output section for an input section found in a input
936 // file. ORDER is where this section should appear in the output
937 // sections. IS_RELRO is true for a relro section. This will return
938 // NULL if the input section should be discarded. MATCH_INPUT_SPEC
939 // is true if the section name should be matched against input specs
940 // in a linker script.
943 Layout::choose_output_section(const Relobj* relobj, const char* name,
944 elfcpp::Elf_Word type, elfcpp::Elf_Xword flags,
945 bool is_input_section, Output_section_order order,
946 bool is_relro, bool is_reloc,
947 bool match_input_spec)
949 // We should not see any input sections after we have attached
950 // sections to segments.
951 gold_assert(!is_input_section || !this->sections_are_attached_);
953 flags = this->get_output_section_flags(flags);
955 if (this->script_options_->saw_sections_clause() && !is_reloc)
957 // We are using a SECTIONS clause, so the output section is
958 // chosen based only on the name.
960 Script_sections* ss = this->script_options_->script_sections();
961 const char* file_name = relobj == NULL ? NULL : relobj->name().c_str();
962 Output_section** output_section_slot;
963 Script_sections::Section_type script_section_type;
964 const char* orig_name = name;
966 name = ss->output_section_name(file_name, name, &output_section_slot,
967 &script_section_type, &keep,
972 gold_debug(DEBUG_SCRIPT, _("Unable to create output section '%s' "
973 "because it is not allowed by the "
974 "SECTIONS clause of the linker script"),
976 // The SECTIONS clause says to discard this input section.
980 // We can only handle script section types ST_NONE and ST_NOLOAD.
981 switch (script_section_type)
983 case Script_sections::ST_NONE:
985 case Script_sections::ST_NOLOAD:
986 flags &= elfcpp::SHF_ALLOC;
992 // If this is an orphan section--one not mentioned in the linker
993 // script--then OUTPUT_SECTION_SLOT will be NULL, and we do the
994 // default processing below.
996 if (output_section_slot != NULL)
998 if (*output_section_slot != NULL)
1000 (*output_section_slot)->update_flags_for_input_section(flags);
1001 return *output_section_slot;
1004 // We don't put sections found in the linker script into
1005 // SECTION_NAME_MAP_. That keeps us from getting confused
1006 // if an orphan section is mapped to a section with the same
1007 // name as one in the linker script.
1009 name = this->namepool_.add(name, false, NULL);
1011 Output_section* os = this->make_output_section(name, type, flags,
1014 os->set_found_in_sections_clause();
1016 // Special handling for NOLOAD sections.
1017 if (script_section_type == Script_sections::ST_NOLOAD)
1019 os->set_is_noload();
1021 // The constructor of Output_section sets addresses of non-ALLOC
1022 // sections to 0 by default. We don't want that for NOLOAD
1023 // sections even if they have no SHF_ALLOC flag.
1024 if ((os->flags() & elfcpp::SHF_ALLOC) == 0
1025 && os->is_address_valid())
1027 gold_assert(os->address() == 0
1028 && !os->is_offset_valid()
1029 && !os->is_data_size_valid());
1030 os->reset_address_and_file_offset();
1034 *output_section_slot = os;
1039 // FIXME: Handle SHF_OS_NONCONFORMING somewhere.
1041 size_t len = strlen(name);
1042 std::string uncompressed_name;
1044 // Compressed debug sections should be mapped to the corresponding
1045 // uncompressed section.
1046 if (is_compressed_debug_section(name))
1049 corresponding_uncompressed_section_name(std::string(name, len));
1050 name = uncompressed_name.c_str();
1051 len = uncompressed_name.length();
1054 // Turn NAME from the name of the input section into the name of the
1056 if (is_input_section
1057 && !this->script_options_->saw_sections_clause()
1058 && !parameters->options().relocatable())
1060 const char *orig_name = name;
1061 name = parameters->target().output_section_name(relobj, name, &len);
1063 name = Layout::output_section_name(relobj, orig_name, &len);
1066 Stringpool::Key name_key;
1067 name = this->namepool_.add_with_length(name, len, true, &name_key);
1069 // Find or make the output section. The output section is selected
1070 // based on the section name, type, and flags.
1071 return this->get_output_section(name, name_key, type, flags, order, is_relro);
1074 // For incremental links, record the initial fixed layout of a section
1075 // from the base file, and return a pointer to the Output_section.
1077 template<int size, bool big_endian>
1079 Layout::init_fixed_output_section(const char* name,
1080 elfcpp::Shdr<size, big_endian>& shdr)
1082 unsigned int sh_type = shdr.get_sh_type();
1084 // We preserve the layout of PROGBITS, NOBITS, INIT_ARRAY, FINI_ARRAY,
1085 // PRE_INIT_ARRAY, and NOTE sections.
1086 // All others will be created from scratch and reallocated.
1087 if (!can_incremental_update(sh_type))
1090 // If we're generating a .gdb_index section, we need to regenerate
1092 if (parameters->options().gdb_index()
1093 && sh_type == elfcpp::SHT_PROGBITS
1094 && strcmp(name, ".gdb_index") == 0)
1097 typename elfcpp::Elf_types<size>::Elf_Addr sh_addr = shdr.get_sh_addr();
1098 typename elfcpp::Elf_types<size>::Elf_Off sh_offset = shdr.get_sh_offset();
1099 typename elfcpp::Elf_types<size>::Elf_WXword sh_size = shdr.get_sh_size();
1100 typename elfcpp::Elf_types<size>::Elf_WXword sh_flags = shdr.get_sh_flags();
1101 typename elfcpp::Elf_types<size>::Elf_WXword sh_addralign =
1102 shdr.get_sh_addralign();
1104 // Make the output section.
1105 Stringpool::Key name_key;
1106 name = this->namepool_.add(name, true, &name_key);
1107 Output_section* os = this->get_output_section(name, name_key, sh_type,
1108 sh_flags, ORDER_INVALID, false);
1109 os->set_fixed_layout(sh_addr, sh_offset, sh_size, sh_addralign);
1110 if (sh_type != elfcpp::SHT_NOBITS)
1111 this->free_list_.remove(sh_offset, sh_offset + sh_size);
1115 // Return the index by which an input section should be ordered. This
1116 // is used to sort some .text sections, for compatibility with GNU ld.
1119 Layout::special_ordering_of_input_section(const char* name)
1121 // The GNU linker has some special handling for some sections that
1122 // wind up in the .text section. Sections that start with these
1123 // prefixes must appear first, and must appear in the order listed
1125 static const char* const text_section_sort[] =
1134 i < sizeof(text_section_sort) / sizeof(text_section_sort[0]);
1136 if (is_prefix_of(text_section_sort[i], name))
1142 // Return the output section to use for input section SHNDX, with name
1143 // NAME, with header HEADER, from object OBJECT. RELOC_SHNDX is the
1144 // index of a relocation section which applies to this section, or 0
1145 // if none, or -1U if more than one. RELOC_TYPE is the type of the
1146 // relocation section if there is one. Set *OFF to the offset of this
1147 // input section without the output section. Return NULL if the
1148 // section should be discarded. Set *OFF to -1 if the section
1149 // contents should not be written directly to the output file, but
1150 // will instead receive special handling.
1152 template<int size, bool big_endian>
1154 Layout::layout(Sized_relobj_file<size, big_endian>* object, unsigned int shndx,
1155 const char* name, const elfcpp::Shdr<size, big_endian>& shdr,
1156 unsigned int reloc_shndx, unsigned int, off_t* off)
1160 if (!this->include_section(object, name, shdr))
1163 elfcpp::Elf_Word sh_type = shdr.get_sh_type();
1165 // In a relocatable link a grouped section must not be combined with
1166 // any other sections.
1168 if (parameters->options().relocatable()
1169 && (shdr.get_sh_flags() & elfcpp::SHF_GROUP) != 0)
1171 // Some flags in the input section should not be automatically
1172 // copied to the output section.
1173 elfcpp::Elf_Xword flags = (shdr.get_sh_flags()
1174 & ~ elfcpp::SHF_COMPRESSED);
1175 name = this->namepool_.add(name, true, NULL);
1176 os = this->make_output_section(name, sh_type, flags,
1177 ORDER_INVALID, false);
1181 // Plugins can choose to place one or more subsets of sections in
1182 // unique segments and this is done by mapping these section subsets
1183 // to unique output sections. Check if this section needs to be
1184 // remapped to a unique output section.
1185 Section_segment_map::iterator it
1186 = this->section_segment_map_.find(Const_section_id(object, shndx));
1187 if (it == this->section_segment_map_.end())
1189 os = this->choose_output_section(object, name, sh_type,
1190 shdr.get_sh_flags(), true,
1191 ORDER_INVALID, false, false,
1196 // We know the name of the output section, directly call
1197 // get_output_section here by-passing choose_output_section.
1198 elfcpp::Elf_Xword flags
1199 = this->get_output_section_flags(shdr.get_sh_flags());
1201 const char* os_name = it->second->name;
1202 Stringpool::Key name_key;
1203 os_name = this->namepool_.add(os_name, true, &name_key);
1204 os = this->get_output_section(os_name, name_key, sh_type, flags,
1205 ORDER_INVALID, false);
1206 if (!os->is_unique_segment())
1208 os->set_is_unique_segment();
1209 os->set_extra_segment_flags(it->second->flags);
1210 os->set_segment_alignment(it->second->align);
1217 // By default the GNU linker sorts input sections whose names match
1218 // .ctors.*, .dtors.*, .init_array.*, or .fini_array.*. The
1219 // sections are sorted by name. This is used to implement
1220 // constructor priority ordering. We are compatible. When we put
1221 // .ctor sections in .init_array and .dtor sections in .fini_array,
1222 // we must also sort plain .ctor and .dtor sections.
1223 if (!this->script_options_->saw_sections_clause()
1224 && !parameters->options().relocatable()
1225 && (is_prefix_of(".ctors.", name)
1226 || is_prefix_of(".dtors.", name)
1227 || is_prefix_of(".init_array.", name)
1228 || is_prefix_of(".fini_array.", name)
1229 || (parameters->options().ctors_in_init_array()
1230 && (strcmp(name, ".ctors") == 0
1231 || strcmp(name, ".dtors") == 0))))
1232 os->set_must_sort_attached_input_sections();
1234 // By default the GNU linker sorts some special text sections ahead
1235 // of others. We are compatible.
1236 if (parameters->options().text_reorder()
1237 && !this->script_options_->saw_sections_clause()
1238 && !this->is_section_ordering_specified()
1239 && !parameters->options().relocatable()
1240 && Layout::special_ordering_of_input_section(name) >= 0)
1241 os->set_must_sort_attached_input_sections();
1243 // If this is a .ctors or .ctors.* section being mapped to a
1244 // .init_array section, or a .dtors or .dtors.* section being mapped
1245 // to a .fini_array section, we will need to reverse the words if
1246 // there is more than one. Record this section for later. See
1247 // ctors_sections_in_init_array above.
1248 if (!this->script_options_->saw_sections_clause()
1249 && !parameters->options().relocatable()
1250 && shdr.get_sh_size() > size / 8
1251 && (((strcmp(name, ".ctors") == 0
1252 || is_prefix_of(".ctors.", name))
1253 && strcmp(os->name(), ".init_array") == 0)
1254 || ((strcmp(name, ".dtors") == 0
1255 || is_prefix_of(".dtors.", name))
1256 && strcmp(os->name(), ".fini_array") == 0)))
1257 ctors_sections_in_init_array.insert(Section_id(object, shndx));
1259 // FIXME: Handle SHF_LINK_ORDER somewhere.
1261 elfcpp::Elf_Xword orig_flags = os->flags();
1263 *off = os->add_input_section(this, object, shndx, name, shdr, reloc_shndx,
1264 this->script_options_->saw_sections_clause());
1266 // If the flags changed, we may have to change the order.
1267 if ((orig_flags & elfcpp::SHF_ALLOC) != 0)
1269 orig_flags &= (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR);
1270 elfcpp::Elf_Xword new_flags =
1271 os->flags() & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR);
1272 if (orig_flags != new_flags)
1273 os->set_order(this->default_section_order(os, false));
1276 this->have_added_input_section_ = true;
1281 // Maps section SECN to SEGMENT s.
1283 Layout::insert_section_segment_map(Const_section_id secn,
1284 Unique_segment_info *s)
1286 gold_assert(this->unique_segment_for_sections_specified_);
1287 this->section_segment_map_[secn] = s;
1290 // Handle a relocation section when doing a relocatable link.
1292 template<int size, bool big_endian>
1294 Layout::layout_reloc(Sized_relobj_file<size, big_endian>* object,
1296 const elfcpp::Shdr<size, big_endian>& shdr,
1297 Output_section* data_section,
1298 Relocatable_relocs* rr)
1300 gold_assert(parameters->options().relocatable()
1301 || parameters->options().emit_relocs());
1303 int sh_type = shdr.get_sh_type();
1306 if (sh_type == elfcpp::SHT_REL)
1308 else if (sh_type == elfcpp::SHT_RELA)
1312 name += data_section->name();
1314 // In a relocatable link relocs for a grouped section must not be
1315 // combined with other reloc sections.
1317 if (!parameters->options().relocatable()
1318 || (data_section->flags() & elfcpp::SHF_GROUP) == 0)
1319 os = this->choose_output_section(object, name.c_str(), sh_type,
1320 shdr.get_sh_flags(), false,
1321 ORDER_INVALID, false, true, false);
1324 const char* n = this->namepool_.add(name.c_str(), true, NULL);
1325 os = this->make_output_section(n, sh_type, shdr.get_sh_flags(),
1326 ORDER_INVALID, false);
1329 os->set_should_link_to_symtab();
1330 os->set_info_section(data_section);
1332 Output_section_data* posd;
1333 if (sh_type == elfcpp::SHT_REL)
1335 os->set_entsize(elfcpp::Elf_sizes<size>::rel_size);
1336 posd = new Output_relocatable_relocs<elfcpp::SHT_REL,
1340 else if (sh_type == elfcpp::SHT_RELA)
1342 os->set_entsize(elfcpp::Elf_sizes<size>::rela_size);
1343 posd = new Output_relocatable_relocs<elfcpp::SHT_RELA,
1350 os->add_output_section_data(posd);
1351 rr->set_output_data(posd);
1356 // Handle a group section when doing a relocatable link.
1358 template<int size, bool big_endian>
1360 Layout::layout_group(Symbol_table* symtab,
1361 Sized_relobj_file<size, big_endian>* object,
1363 const char* group_section_name,
1364 const char* signature,
1365 const elfcpp::Shdr<size, big_endian>& shdr,
1366 elfcpp::Elf_Word flags,
1367 std::vector<unsigned int>* shndxes)
1369 gold_assert(parameters->options().relocatable());
1370 gold_assert(shdr.get_sh_type() == elfcpp::SHT_GROUP);
1371 group_section_name = this->namepool_.add(group_section_name, true, NULL);
1372 Output_section* os = this->make_output_section(group_section_name,
1374 shdr.get_sh_flags(),
1375 ORDER_INVALID, false);
1377 // We need to find a symbol with the signature in the symbol table.
1378 // If we don't find one now, we need to look again later.
1379 Symbol* sym = symtab->lookup(signature, NULL);
1381 os->set_info_symndx(sym);
1384 // Reserve some space to minimize reallocations.
1385 if (this->group_signatures_.empty())
1386 this->group_signatures_.reserve(this->number_of_input_files_ * 16);
1388 // We will wind up using a symbol whose name is the signature.
1389 // So just put the signature in the symbol name pool to save it.
1390 signature = symtab->canonicalize_name(signature);
1391 this->group_signatures_.push_back(Group_signature(os, signature));
1394 os->set_should_link_to_symtab();
1397 section_size_type entry_count =
1398 convert_to_section_size_type(shdr.get_sh_size() / 4);
1399 Output_section_data* posd =
1400 new Output_data_group<size, big_endian>(object, entry_count, flags,
1402 os->add_output_section_data(posd);
1405 // Special GNU handling of sections name .eh_frame. They will
1406 // normally hold exception frame data as defined by the C++ ABI
1407 // (http://codesourcery.com/cxx-abi/).
1409 template<int size, bool big_endian>
1411 Layout::layout_eh_frame(Sized_relobj_file<size, big_endian>* object,
1412 const unsigned char* symbols,
1414 const unsigned char* symbol_names,
1415 off_t symbol_names_size,
1417 const elfcpp::Shdr<size, big_endian>& shdr,
1418 unsigned int reloc_shndx, unsigned int reloc_type,
1421 gold_assert(shdr.get_sh_type() == elfcpp::SHT_PROGBITS
1422 || shdr.get_sh_type() == elfcpp::SHT_X86_64_UNWIND);
1423 gold_assert((shdr.get_sh_flags() & elfcpp::SHF_ALLOC) != 0);
1425 Output_section* os = this->make_eh_frame_section(object);
1429 gold_assert(this->eh_frame_section_ == os);
1431 elfcpp::Elf_Xword orig_flags = os->flags();
1433 Eh_frame::Eh_frame_section_disposition disp =
1434 Eh_frame::EH_UNRECOGNIZED_SECTION;
1435 if (!parameters->incremental())
1437 disp = this->eh_frame_data_->add_ehframe_input_section(object,
1447 if (disp == Eh_frame::EH_OPTIMIZABLE_SECTION)
1449 os->update_flags_for_input_section(shdr.get_sh_flags());
1451 // A writable .eh_frame section is a RELRO section.
1452 if ((orig_flags & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR))
1453 != (os->flags() & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR)))
1456 os->set_order(ORDER_RELRO);
1463 if (disp == Eh_frame::EH_END_MARKER_SECTION && !this->added_eh_frame_data_)
1465 // We found the end marker section, so now we can add the set of
1466 // optimized sections to the output section. We need to postpone
1467 // adding this until we've found a section we can optimize so that
1468 // the .eh_frame section in crtbeginT.o winds up at the start of
1469 // the output section.
1470 os->add_output_section_data(this->eh_frame_data_);
1471 this->added_eh_frame_data_ = true;
1474 // We couldn't handle this .eh_frame section for some reason.
1475 // Add it as a normal section.
1476 bool saw_sections_clause = this->script_options_->saw_sections_clause();
1477 *off = os->add_input_section(this, object, shndx, ".eh_frame", shdr,
1478 reloc_shndx, saw_sections_clause);
1479 this->have_added_input_section_ = true;
1481 if ((orig_flags & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR))
1482 != (os->flags() & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR)))
1483 os->set_order(this->default_section_order(os, false));
1489 Layout::finalize_eh_frame_section()
1491 // If we never found an end marker section, we need to add the
1492 // optimized eh sections to the output section now.
1493 if (!parameters->incremental()
1494 && this->eh_frame_section_ != NULL
1495 && !this->added_eh_frame_data_)
1497 this->eh_frame_section_->add_output_section_data(this->eh_frame_data_);
1498 this->added_eh_frame_data_ = true;
1502 // Create and return the magic .eh_frame section. Create
1503 // .eh_frame_hdr also if appropriate. OBJECT is the object with the
1504 // input .eh_frame section; it may be NULL.
1507 Layout::make_eh_frame_section(const Relobj* object)
1509 // FIXME: On x86_64, this could use SHT_X86_64_UNWIND rather than
1511 Output_section* os = this->choose_output_section(object, ".eh_frame",
1512 elfcpp::SHT_PROGBITS,
1513 elfcpp::SHF_ALLOC, false,
1514 ORDER_EHFRAME, false, false,
1519 if (this->eh_frame_section_ == NULL)
1521 this->eh_frame_section_ = os;
1522 this->eh_frame_data_ = new Eh_frame();
1524 // For incremental linking, we do not optimize .eh_frame sections
1525 // or create a .eh_frame_hdr section.
1526 if (parameters->options().eh_frame_hdr() && !parameters->incremental())
1528 Output_section* hdr_os =
1529 this->choose_output_section(NULL, ".eh_frame_hdr",
1530 elfcpp::SHT_PROGBITS,
1531 elfcpp::SHF_ALLOC, false,
1532 ORDER_EHFRAME, false, false,
1537 Eh_frame_hdr* hdr_posd = new Eh_frame_hdr(os,
1538 this->eh_frame_data_);
1539 hdr_os->add_output_section_data(hdr_posd);
1541 hdr_os->set_after_input_sections();
1543 if (!this->script_options_->saw_phdrs_clause())
1545 Output_segment* hdr_oseg;
1546 hdr_oseg = this->make_output_segment(elfcpp::PT_GNU_EH_FRAME,
1548 hdr_oseg->add_output_section_to_nonload(hdr_os,
1552 this->eh_frame_data_->set_eh_frame_hdr(hdr_posd);
1560 // Add an exception frame for a PLT. This is called from target code.
1563 Layout::add_eh_frame_for_plt(Output_data* plt, const unsigned char* cie_data,
1564 size_t cie_length, const unsigned char* fde_data,
1567 if (parameters->incremental())
1569 // FIXME: Maybe this could work some day....
1572 Output_section* os = this->make_eh_frame_section(NULL);
1575 this->eh_frame_data_->add_ehframe_for_plt(plt, cie_data, cie_length,
1576 fde_data, fde_length);
1577 if (!this->added_eh_frame_data_)
1579 os->add_output_section_data(this->eh_frame_data_);
1580 this->added_eh_frame_data_ = true;
1584 // Scan a .debug_info or .debug_types section, and add summary
1585 // information to the .gdb_index section.
1587 template<int size, bool big_endian>
1589 Layout::add_to_gdb_index(bool is_type_unit,
1590 Sized_relobj<size, big_endian>* object,
1591 const unsigned char* symbols,
1594 unsigned int reloc_shndx,
1595 unsigned int reloc_type)
1597 if (this->gdb_index_data_ == NULL)
1599 Output_section* os = this->choose_output_section(NULL, ".gdb_index",
1600 elfcpp::SHT_PROGBITS, 0,
1601 false, ORDER_INVALID,
1602 false, false, false);
1606 this->gdb_index_data_ = new Gdb_index(os);
1607 os->add_output_section_data(this->gdb_index_data_);
1608 os->set_after_input_sections();
1611 this->gdb_index_data_->scan_debug_info(is_type_unit, object, symbols,
1612 symbols_size, shndx, reloc_shndx,
1616 // Add POSD to an output section using NAME, TYPE, and FLAGS. Return
1617 // the output section.
1620 Layout::add_output_section_data(const char* name, elfcpp::Elf_Word type,
1621 elfcpp::Elf_Xword flags,
1622 Output_section_data* posd,
1623 Output_section_order order, bool is_relro)
1625 Output_section* os = this->choose_output_section(NULL, name, type, flags,
1626 false, order, is_relro,
1629 os->add_output_section_data(posd);
1633 // Map section flags to segment flags.
1636 Layout::section_flags_to_segment(elfcpp::Elf_Xword flags)
1638 elfcpp::Elf_Word ret = elfcpp::PF_R;
1639 if ((flags & elfcpp::SHF_WRITE) != 0)
1640 ret |= elfcpp::PF_W;
1641 if ((flags & elfcpp::SHF_EXECINSTR) != 0)
1642 ret |= elfcpp::PF_X;
1646 // Make a new Output_section, and attach it to segments as
1647 // appropriate. ORDER is the order in which this section should
1648 // appear in the output segment. IS_RELRO is true if this is a relro
1649 // (read-only after relocations) section.
1652 Layout::make_output_section(const char* name, elfcpp::Elf_Word type,
1653 elfcpp::Elf_Xword flags,
1654 Output_section_order order, bool is_relro)
1657 if ((flags & elfcpp::SHF_ALLOC) == 0
1658 && strcmp(parameters->options().compress_debug_sections(), "none") != 0
1659 && is_compressible_debug_section(name))
1660 os = new Output_compressed_section(¶meters->options(), name, type,
1662 else if ((flags & elfcpp::SHF_ALLOC) == 0
1663 && parameters->options().strip_debug_non_line()
1664 && strcmp(".debug_abbrev", name) == 0)
1666 os = this->debug_abbrev_ = new Output_reduced_debug_abbrev_section(
1668 if (this->debug_info_)
1669 this->debug_info_->set_abbreviations(this->debug_abbrev_);
1671 else if ((flags & elfcpp::SHF_ALLOC) == 0
1672 && parameters->options().strip_debug_non_line()
1673 && strcmp(".debug_info", name) == 0)
1675 os = this->debug_info_ = new Output_reduced_debug_info_section(
1677 if (this->debug_abbrev_)
1678 this->debug_info_->set_abbreviations(this->debug_abbrev_);
1682 // Sometimes .init_array*, .preinit_array* and .fini_array* do
1683 // not have correct section types. Force them here.
1684 if (type == elfcpp::SHT_PROGBITS)
1686 if (is_prefix_of(".init_array", name))
1687 type = elfcpp::SHT_INIT_ARRAY;
1688 else if (is_prefix_of(".preinit_array", name))
1689 type = elfcpp::SHT_PREINIT_ARRAY;
1690 else if (is_prefix_of(".fini_array", name))
1691 type = elfcpp::SHT_FINI_ARRAY;
1694 // FIXME: const_cast is ugly.
1695 Target* target = const_cast<Target*>(¶meters->target());
1696 os = target->make_output_section(name, type, flags);
1699 // With -z relro, we have to recognize the special sections by name.
1700 // There is no other way.
1701 bool is_relro_local = false;
1702 if (!this->script_options_->saw_sections_clause()
1703 && parameters->options().relro()
1704 && (flags & elfcpp::SHF_ALLOC) != 0
1705 && (flags & elfcpp::SHF_WRITE) != 0)
1707 if (type == elfcpp::SHT_PROGBITS)
1709 if ((flags & elfcpp::SHF_TLS) != 0)
1711 else if (strcmp(name, ".data.rel.ro") == 0)
1713 else if (strcmp(name, ".data.rel.ro.local") == 0)
1716 is_relro_local = true;
1718 else if (strcmp(name, ".ctors") == 0
1719 || strcmp(name, ".dtors") == 0
1720 || strcmp(name, ".jcr") == 0)
1723 else if (type == elfcpp::SHT_INIT_ARRAY
1724 || type == elfcpp::SHT_FINI_ARRAY
1725 || type == elfcpp::SHT_PREINIT_ARRAY)
1732 if (order == ORDER_INVALID && (flags & elfcpp::SHF_ALLOC) != 0)
1733 order = this->default_section_order(os, is_relro_local);
1735 os->set_order(order);
1737 parameters->target().new_output_section(os);
1739 this->section_list_.push_back(os);
1741 // The GNU linker by default sorts some sections by priority, so we
1742 // do the same. We need to know that this might happen before we
1743 // attach any input sections.
1744 if (!this->script_options_->saw_sections_clause()
1745 && !parameters->options().relocatable()
1746 && (strcmp(name, ".init_array") == 0
1747 || strcmp(name, ".fini_array") == 0
1748 || (!parameters->options().ctors_in_init_array()
1749 && (strcmp(name, ".ctors") == 0
1750 || strcmp(name, ".dtors") == 0))))
1751 os->set_may_sort_attached_input_sections();
1753 // The GNU linker by default sorts .text.{unlikely,exit,startup,hot}
1754 // sections before other .text sections. We are compatible. We
1755 // need to know that this might happen before we attach any input
1757 if (parameters->options().text_reorder()
1758 && !this->script_options_->saw_sections_clause()
1759 && !this->is_section_ordering_specified()
1760 && !parameters->options().relocatable()
1761 && strcmp(name, ".text") == 0)
1762 os->set_may_sort_attached_input_sections();
1764 // GNU linker sorts section by name with --sort-section=name.
1765 if (strcmp(parameters->options().sort_section(), "name") == 0)
1766 os->set_must_sort_attached_input_sections();
1768 // Check for .stab*str sections, as .stab* sections need to link to
1770 if (type == elfcpp::SHT_STRTAB
1771 && !this->have_stabstr_section_
1772 && strncmp(name, ".stab", 5) == 0
1773 && strcmp(name + strlen(name) - 3, "str") == 0)
1774 this->have_stabstr_section_ = true;
1776 // During a full incremental link, we add patch space to most
1777 // PROGBITS and NOBITS sections. Flag those that may be
1778 // arbitrarily padded.
1779 if ((type == elfcpp::SHT_PROGBITS || type == elfcpp::SHT_NOBITS)
1780 && order != ORDER_INTERP
1781 && order != ORDER_INIT
1782 && order != ORDER_PLT
1783 && order != ORDER_FINI
1784 && order != ORDER_RELRO_LAST
1785 && order != ORDER_NON_RELRO_FIRST
1786 && strcmp(name, ".eh_frame") != 0
1787 && strcmp(name, ".ctors") != 0
1788 && strcmp(name, ".dtors") != 0
1789 && strcmp(name, ".jcr") != 0)
1791 os->set_is_patch_space_allowed();
1793 // Certain sections require "holes" to be filled with
1794 // specific fill patterns. These fill patterns may have
1795 // a minimum size, so we must prevent allocations from the
1796 // free list that leave a hole smaller than the minimum.
1797 if (strcmp(name, ".debug_info") == 0)
1798 os->set_free_space_fill(new Output_fill_debug_info(false));
1799 else if (strcmp(name, ".debug_types") == 0)
1800 os->set_free_space_fill(new Output_fill_debug_info(true));
1801 else if (strcmp(name, ".debug_line") == 0)
1802 os->set_free_space_fill(new Output_fill_debug_line());
1805 // If we have already attached the sections to segments, then we
1806 // need to attach this one now. This happens for sections created
1807 // directly by the linker.
1808 if (this->sections_are_attached_)
1809 this->attach_section_to_segment(¶meters->target(), os);
1814 // Return the default order in which a section should be placed in an
1815 // output segment. This function captures a lot of the ideas in
1816 // ld/scripttempl/elf.sc in the GNU linker. Note that the order of a
1817 // linker created section is normally set when the section is created;
1818 // this function is used for input sections.
1820 Output_section_order
1821 Layout::default_section_order(Output_section* os, bool is_relro_local)
1823 gold_assert((os->flags() & elfcpp::SHF_ALLOC) != 0);
1824 bool is_write = (os->flags() & elfcpp::SHF_WRITE) != 0;
1825 bool is_execinstr = (os->flags() & elfcpp::SHF_EXECINSTR) != 0;
1826 bool is_bss = false;
1831 case elfcpp::SHT_PROGBITS:
1833 case elfcpp::SHT_NOBITS:
1836 case elfcpp::SHT_RELA:
1837 case elfcpp::SHT_REL:
1839 return ORDER_DYNAMIC_RELOCS;
1841 case elfcpp::SHT_HASH:
1842 case elfcpp::SHT_DYNAMIC:
1843 case elfcpp::SHT_SHLIB:
1844 case elfcpp::SHT_DYNSYM:
1845 case elfcpp::SHT_GNU_HASH:
1846 case elfcpp::SHT_GNU_verdef:
1847 case elfcpp::SHT_GNU_verneed:
1848 case elfcpp::SHT_GNU_versym:
1850 return ORDER_DYNAMIC_LINKER;
1852 case elfcpp::SHT_NOTE:
1853 return is_write ? ORDER_RW_NOTE : ORDER_RO_NOTE;
1856 if ((os->flags() & elfcpp::SHF_TLS) != 0)
1857 return is_bss ? ORDER_TLS_BSS : ORDER_TLS_DATA;
1859 if (!is_bss && !is_write)
1863 if (strcmp(os->name(), ".init") == 0)
1865 else if (strcmp(os->name(), ".fini") == 0)
1868 return is_execinstr ? ORDER_TEXT : ORDER_READONLY;
1872 return is_relro_local ? ORDER_RELRO_LOCAL : ORDER_RELRO;
1874 if (os->is_small_section())
1875 return is_bss ? ORDER_SMALL_BSS : ORDER_SMALL_DATA;
1876 if (os->is_large_section())
1877 return is_bss ? ORDER_LARGE_BSS : ORDER_LARGE_DATA;
1879 return is_bss ? ORDER_BSS : ORDER_DATA;
1882 // Attach output sections to segments. This is called after we have
1883 // seen all the input sections.
1886 Layout::attach_sections_to_segments(const Target* target)
1888 for (Section_list::iterator p = this->section_list_.begin();
1889 p != this->section_list_.end();
1891 this->attach_section_to_segment(target, *p);
1893 this->sections_are_attached_ = true;
1896 // Attach an output section to a segment.
1899 Layout::attach_section_to_segment(const Target* target, Output_section* os)
1901 if ((os->flags() & elfcpp::SHF_ALLOC) == 0)
1902 this->unattached_section_list_.push_back(os);
1904 this->attach_allocated_section_to_segment(target, os);
1907 // Attach an allocated output section to a segment.
1910 Layout::attach_allocated_section_to_segment(const Target* target,
1913 elfcpp::Elf_Xword flags = os->flags();
1914 gold_assert((flags & elfcpp::SHF_ALLOC) != 0);
1916 if (parameters->options().relocatable())
1919 // If we have a SECTIONS clause, we can't handle the attachment to
1920 // segments until after we've seen all the sections.
1921 if (this->script_options_->saw_sections_clause())
1924 gold_assert(!this->script_options_->saw_phdrs_clause());
1926 // This output section goes into a PT_LOAD segment.
1928 elfcpp::Elf_Word seg_flags = Layout::section_flags_to_segment(flags);
1930 // If this output section's segment has extra flags that need to be set,
1931 // coming from a linker plugin, do that.
1932 seg_flags |= os->extra_segment_flags();
1934 // Check for --section-start.
1936 bool is_address_set = parameters->options().section_start(os->name(), &addr);
1938 // In general the only thing we really care about for PT_LOAD
1939 // segments is whether or not they are writable or executable,
1940 // so that is how we search for them.
1941 // Large data sections also go into their own PT_LOAD segment.
1942 // People who need segments sorted on some other basis will
1943 // have to use a linker script.
1945 Segment_list::const_iterator p;
1946 if (!os->is_unique_segment())
1948 for (p = this->segment_list_.begin();
1949 p != this->segment_list_.end();
1952 if ((*p)->type() != elfcpp::PT_LOAD)
1954 if ((*p)->is_unique_segment())
1956 if (!parameters->options().omagic()
1957 && ((*p)->flags() & elfcpp::PF_W) != (seg_flags & elfcpp::PF_W))
1959 if ((target->isolate_execinstr() || parameters->options().rosegment())
1960 && ((*p)->flags() & elfcpp::PF_X) != (seg_flags & elfcpp::PF_X))
1962 // If -Tbss was specified, we need to separate the data and BSS
1964 if (parameters->options().user_set_Tbss())
1966 if ((os->type() == elfcpp::SHT_NOBITS)
1967 == (*p)->has_any_data_sections())
1970 if (os->is_large_data_section() && !(*p)->is_large_data_segment())
1975 if ((*p)->are_addresses_set())
1978 (*p)->add_initial_output_data(os);
1979 (*p)->update_flags_for_output_section(seg_flags);
1980 (*p)->set_addresses(addr, addr);
1984 (*p)->add_output_section_to_load(this, os, seg_flags);
1989 if (p == this->segment_list_.end()
1990 || os->is_unique_segment())
1992 Output_segment* oseg = this->make_output_segment(elfcpp::PT_LOAD,
1994 if (os->is_large_data_section())
1995 oseg->set_is_large_data_segment();
1996 oseg->add_output_section_to_load(this, os, seg_flags);
1998 oseg->set_addresses(addr, addr);
1999 // Check if segment should be marked unique. For segments marked
2000 // unique by linker plugins, set the new alignment if specified.
2001 if (os->is_unique_segment())
2003 oseg->set_is_unique_segment();
2004 if (os->segment_alignment() != 0)
2005 oseg->set_minimum_p_align(os->segment_alignment());
2009 // If we see a loadable SHT_NOTE section, we create a PT_NOTE
2011 if (os->type() == elfcpp::SHT_NOTE)
2013 // See if we already have an equivalent PT_NOTE segment.
2014 for (p = this->segment_list_.begin();
2015 p != segment_list_.end();
2018 if ((*p)->type() == elfcpp::PT_NOTE
2019 && (((*p)->flags() & elfcpp::PF_W)
2020 == (seg_flags & elfcpp::PF_W)))
2022 (*p)->add_output_section_to_nonload(os, seg_flags);
2027 if (p == this->segment_list_.end())
2029 Output_segment* oseg = this->make_output_segment(elfcpp::PT_NOTE,
2031 oseg->add_output_section_to_nonload(os, seg_flags);
2035 // If we see a loadable SHF_TLS section, we create a PT_TLS
2036 // segment. There can only be one such segment.
2037 if ((flags & elfcpp::SHF_TLS) != 0)
2039 if (this->tls_segment_ == NULL)
2040 this->make_output_segment(elfcpp::PT_TLS, seg_flags);
2041 this->tls_segment_->add_output_section_to_nonload(os, seg_flags);
2044 // If -z relro is in effect, and we see a relro section, we create a
2045 // PT_GNU_RELRO segment. There can only be one such segment.
2046 if (os->is_relro() && parameters->options().relro())
2048 gold_assert(seg_flags == (elfcpp::PF_R | elfcpp::PF_W));
2049 if (this->relro_segment_ == NULL)
2050 this->make_output_segment(elfcpp::PT_GNU_RELRO, seg_flags);
2051 this->relro_segment_->add_output_section_to_nonload(os, seg_flags);
2054 // If we see a section named .interp, put it into a PT_INTERP
2055 // segment. This seems broken to me, but this is what GNU ld does,
2056 // and glibc expects it.
2057 if (strcmp(os->name(), ".interp") == 0
2058 && !this->script_options_->saw_phdrs_clause())
2060 if (this->interp_segment_ == NULL)
2061 this->make_output_segment(elfcpp::PT_INTERP, seg_flags);
2063 gold_warning(_("multiple '.interp' sections in input files "
2064 "may cause confusing PT_INTERP segment"));
2065 this->interp_segment_->add_output_section_to_nonload(os, seg_flags);
2069 // Make an output section for a script.
2072 Layout::make_output_section_for_script(
2074 Script_sections::Section_type section_type)
2076 name = this->namepool_.add(name, false, NULL);
2077 elfcpp::Elf_Xword sh_flags = elfcpp::SHF_ALLOC;
2078 if (section_type == Script_sections::ST_NOLOAD)
2080 Output_section* os = this->make_output_section(name, elfcpp::SHT_PROGBITS,
2081 sh_flags, ORDER_INVALID,
2083 os->set_found_in_sections_clause();
2084 if (section_type == Script_sections::ST_NOLOAD)
2085 os->set_is_noload();
2089 // Return the number of segments we expect to see.
2092 Layout::expected_segment_count() const
2094 size_t ret = this->segment_list_.size();
2096 // If we didn't see a SECTIONS clause in a linker script, we should
2097 // already have the complete list of segments. Otherwise we ask the
2098 // SECTIONS clause how many segments it expects, and add in the ones
2099 // we already have (PT_GNU_STACK, PT_GNU_EH_FRAME, etc.)
2101 if (!this->script_options_->saw_sections_clause())
2105 const Script_sections* ss = this->script_options_->script_sections();
2106 return ret + ss->expected_segment_count(this);
2110 // Handle the .note.GNU-stack section at layout time. SEEN_GNU_STACK
2111 // is whether we saw a .note.GNU-stack section in the object file.
2112 // GNU_STACK_FLAGS is the section flags. The flags give the
2113 // protection required for stack memory. We record this in an
2114 // executable as a PT_GNU_STACK segment. If an object file does not
2115 // have a .note.GNU-stack segment, we must assume that it is an old
2116 // object. On some targets that will force an executable stack.
2119 Layout::layout_gnu_stack(bool seen_gnu_stack, uint64_t gnu_stack_flags,
2122 if (!seen_gnu_stack)
2124 this->input_without_gnu_stack_note_ = true;
2125 if (parameters->options().warn_execstack()
2126 && parameters->target().is_default_stack_executable())
2127 gold_warning(_("%s: missing .note.GNU-stack section"
2128 " implies executable stack"),
2129 obj->name().c_str());
2133 this->input_with_gnu_stack_note_ = true;
2134 if ((gnu_stack_flags & elfcpp::SHF_EXECINSTR) != 0)
2136 this->input_requires_executable_stack_ = true;
2137 if (parameters->options().warn_execstack())
2138 gold_warning(_("%s: requires executable stack"),
2139 obj->name().c_str());
2144 // Create automatic note sections.
2147 Layout::create_notes()
2149 this->create_gold_note();
2150 this->create_stack_segment();
2151 this->create_build_id();
2154 // Create the dynamic sections which are needed before we read the
2158 Layout::create_initial_dynamic_sections(Symbol_table* symtab)
2160 if (parameters->doing_static_link())
2163 this->dynamic_section_ = this->choose_output_section(NULL, ".dynamic",
2164 elfcpp::SHT_DYNAMIC,
2166 | elfcpp::SHF_WRITE),
2168 true, false, false);
2170 // A linker script may discard .dynamic, so check for NULL.
2171 if (this->dynamic_section_ != NULL)
2173 this->dynamic_symbol_ =
2174 symtab->define_in_output_data("_DYNAMIC", NULL,
2175 Symbol_table::PREDEFINED,
2176 this->dynamic_section_, 0, 0,
2177 elfcpp::STT_OBJECT, elfcpp::STB_LOCAL,
2178 elfcpp::STV_HIDDEN, 0, false, false);
2180 this->dynamic_data_ = new Output_data_dynamic(&this->dynpool_);
2182 this->dynamic_section_->add_output_section_data(this->dynamic_data_);
2186 // For each output section whose name can be represented as C symbol,
2187 // define __start and __stop symbols for the section. This is a GNU
2191 Layout::define_section_symbols(Symbol_table* symtab)
2193 for (Section_list::const_iterator p = this->section_list_.begin();
2194 p != this->section_list_.end();
2197 const char* const name = (*p)->name();
2198 if (is_cident(name))
2200 const std::string name_string(name);
2201 const std::string start_name(cident_section_start_prefix
2203 const std::string stop_name(cident_section_stop_prefix
2206 symtab->define_in_output_data(start_name.c_str(),
2208 Symbol_table::PREDEFINED,
2214 elfcpp::STV_DEFAULT,
2216 false, // offset_is_from_end
2217 true); // only_if_ref
2219 symtab->define_in_output_data(stop_name.c_str(),
2221 Symbol_table::PREDEFINED,
2227 elfcpp::STV_DEFAULT,
2229 true, // offset_is_from_end
2230 true); // only_if_ref
2235 // Define symbols for group signatures.
2238 Layout::define_group_signatures(Symbol_table* symtab)
2240 for (Group_signatures::iterator p = this->group_signatures_.begin();
2241 p != this->group_signatures_.end();
2244 Symbol* sym = symtab->lookup(p->signature, NULL);
2246 p->section->set_info_symndx(sym);
2249 // Force the name of the group section to the group
2250 // signature, and use the group's section symbol as the
2251 // signature symbol.
2252 if (strcmp(p->section->name(), p->signature) != 0)
2254 const char* name = this->namepool_.add(p->signature,
2256 p->section->set_name(name);
2258 p->section->set_needs_symtab_index();
2259 p->section->set_info_section_symndx(p->section);
2263 this->group_signatures_.clear();
2266 // Find the first read-only PT_LOAD segment, creating one if
2270 Layout::find_first_load_seg(const Target* target)
2272 Output_segment* best = NULL;
2273 for (Segment_list::const_iterator p = this->segment_list_.begin();
2274 p != this->segment_list_.end();
2277 if ((*p)->type() == elfcpp::PT_LOAD
2278 && ((*p)->flags() & elfcpp::PF_R) != 0
2279 && (parameters->options().omagic()
2280 || ((*p)->flags() & elfcpp::PF_W) == 0)
2281 && (!target->isolate_execinstr()
2282 || ((*p)->flags() & elfcpp::PF_X) == 0))
2284 if (best == NULL || this->segment_precedes(*p, best))
2291 gold_assert(!this->script_options_->saw_phdrs_clause());
2293 Output_segment* load_seg = this->make_output_segment(elfcpp::PT_LOAD,
2298 // Save states of all current output segments. Store saved states
2299 // in SEGMENT_STATES.
2302 Layout::save_segments(Segment_states* segment_states)
2304 for (Segment_list::const_iterator p = this->segment_list_.begin();
2305 p != this->segment_list_.end();
2308 Output_segment* segment = *p;
2310 Output_segment* copy = new Output_segment(*segment);
2311 (*segment_states)[segment] = copy;
2315 // Restore states of output segments and delete any segment not found in
2319 Layout::restore_segments(const Segment_states* segment_states)
2321 // Go through the segment list and remove any segment added in the
2323 this->tls_segment_ = NULL;
2324 this->relro_segment_ = NULL;
2325 Segment_list::iterator list_iter = this->segment_list_.begin();
2326 while (list_iter != this->segment_list_.end())
2328 Output_segment* segment = *list_iter;
2329 Segment_states::const_iterator states_iter =
2330 segment_states->find(segment);
2331 if (states_iter != segment_states->end())
2333 const Output_segment* copy = states_iter->second;
2334 // Shallow copy to restore states.
2337 // Also fix up TLS and RELRO segment pointers as appropriate.
2338 if (segment->type() == elfcpp::PT_TLS)
2339 this->tls_segment_ = segment;
2340 else if (segment->type() == elfcpp::PT_GNU_RELRO)
2341 this->relro_segment_ = segment;
2347 list_iter = this->segment_list_.erase(list_iter);
2348 // This is a segment created during section layout. It should be
2349 // safe to remove it since we should have removed all pointers to it.
2355 // Clean up after relaxation so that sections can be laid out again.
2358 Layout::clean_up_after_relaxation()
2360 // Restore the segments to point state just prior to the relaxation loop.
2361 Script_sections* script_section = this->script_options_->script_sections();
2362 script_section->release_segments();
2363 this->restore_segments(this->segment_states_);
2365 // Reset section addresses and file offsets
2366 for (Section_list::iterator p = this->section_list_.begin();
2367 p != this->section_list_.end();
2370 (*p)->restore_states();
2372 // If an input section changes size because of relaxation,
2373 // we need to adjust the section offsets of all input sections.
2374 // after such a section.
2375 if ((*p)->section_offsets_need_adjustment())
2376 (*p)->adjust_section_offsets();
2378 (*p)->reset_address_and_file_offset();
2381 // Reset special output object address and file offsets.
2382 for (Data_list::iterator p = this->special_output_list_.begin();
2383 p != this->special_output_list_.end();
2385 (*p)->reset_address_and_file_offset();
2387 // A linker script may have created some output section data objects.
2388 // They are useless now.
2389 for (Output_section_data_list::const_iterator p =
2390 this->script_output_section_data_list_.begin();
2391 p != this->script_output_section_data_list_.end();
2394 this->script_output_section_data_list_.clear();
2396 // Special-case fill output objects are recreated each time through
2397 // the relaxation loop.
2398 this->reset_relax_output();
2402 Layout::reset_relax_output()
2404 for (Data_list::const_iterator p = this->relax_output_list_.begin();
2405 p != this->relax_output_list_.end();
2408 this->relax_output_list_.clear();
2411 // Prepare for relaxation.
2414 Layout::prepare_for_relaxation()
2416 // Create an relaxation debug check if in debugging mode.
2417 if (is_debugging_enabled(DEBUG_RELAXATION))
2418 this->relaxation_debug_check_ = new Relaxation_debug_check();
2420 // Save segment states.
2421 this->segment_states_ = new Segment_states();
2422 this->save_segments(this->segment_states_);
2424 for(Section_list::const_iterator p = this->section_list_.begin();
2425 p != this->section_list_.end();
2427 (*p)->save_states();
2429 if (is_debugging_enabled(DEBUG_RELAXATION))
2430 this->relaxation_debug_check_->check_output_data_for_reset_values(
2431 this->section_list_, this->special_output_list_,
2432 this->relax_output_list_);
2434 // Also enable recording of output section data from scripts.
2435 this->record_output_section_data_from_script_ = true;
2438 // If the user set the address of the text segment, that may not be
2439 // compatible with putting the segment headers and file headers into
2440 // that segment. For isolate_execinstr() targets, it's the rodata
2441 // segment rather than text where we might put the headers.
2443 load_seg_unusable_for_headers(const Target* target)
2445 const General_options& options = parameters->options();
2446 if (target->isolate_execinstr())
2447 return (options.user_set_Trodata_segment()
2448 && options.Trodata_segment() % target->abi_pagesize() != 0);
2450 return (options.user_set_Ttext()
2451 && options.Ttext() % target->abi_pagesize() != 0);
2454 // Relaxation loop body: If target has no relaxation, this runs only once
2455 // Otherwise, the target relaxation hook is called at the end of
2456 // each iteration. If the hook returns true, it means re-layout of
2457 // section is required.
2459 // The number of segments created by a linking script without a PHDRS
2460 // clause may be affected by section sizes and alignments. There is
2461 // a remote chance that relaxation causes different number of PT_LOAD
2462 // segments are created and sections are attached to different segments.
2463 // Therefore, we always throw away all segments created during section
2464 // layout. In order to be able to restart the section layout, we keep
2465 // a copy of the segment list right before the relaxation loop and use
2466 // that to restore the segments.
2468 // PASS is the current relaxation pass number.
2469 // SYMTAB is a symbol table.
2470 // PLOAD_SEG is the address of a pointer for the load segment.
2471 // PHDR_SEG is a pointer to the PHDR segment.
2472 // SEGMENT_HEADERS points to the output segment header.
2473 // FILE_HEADER points to the output file header.
2474 // PSHNDX is the address to store the output section index.
2477 Layout::relaxation_loop_body(
2480 Symbol_table* symtab,
2481 Output_segment** pload_seg,
2482 Output_segment* phdr_seg,
2483 Output_segment_headers* segment_headers,
2484 Output_file_header* file_header,
2485 unsigned int* pshndx)
2487 // If this is not the first iteration, we need to clean up after
2488 // relaxation so that we can lay out the sections again.
2490 this->clean_up_after_relaxation();
2492 // If there is a SECTIONS clause, put all the input sections into
2493 // the required order.
2494 Output_segment* load_seg;
2495 if (this->script_options_->saw_sections_clause())
2496 load_seg = this->set_section_addresses_from_script(symtab);
2497 else if (parameters->options().relocatable())
2500 load_seg = this->find_first_load_seg(target);
2502 if (parameters->options().oformat_enum()
2503 != General_options::OBJECT_FORMAT_ELF)
2506 if (load_seg_unusable_for_headers(target))
2512 gold_assert(phdr_seg == NULL
2514 || this->script_options_->saw_sections_clause());
2516 // If the address of the load segment we found has been set by
2517 // --section-start rather than by a script, then adjust the VMA and
2518 // LMA downward if possible to include the file and section headers.
2519 uint64_t header_gap = 0;
2520 if (load_seg != NULL
2521 && load_seg->are_addresses_set()
2522 && !this->script_options_->saw_sections_clause()
2523 && !parameters->options().relocatable())
2525 file_header->finalize_data_size();
2526 segment_headers->finalize_data_size();
2527 size_t sizeof_headers = (file_header->data_size()
2528 + segment_headers->data_size());
2529 const uint64_t abi_pagesize = target->abi_pagesize();
2530 uint64_t hdr_paddr = load_seg->paddr() - sizeof_headers;
2531 hdr_paddr &= ~(abi_pagesize - 1);
2532 uint64_t subtract = load_seg->paddr() - hdr_paddr;
2533 if (load_seg->paddr() < subtract || load_seg->vaddr() < subtract)
2537 load_seg->set_addresses(load_seg->vaddr() - subtract,
2538 load_seg->paddr() - subtract);
2539 header_gap = subtract - sizeof_headers;
2543 // Lay out the segment headers.
2544 if (!parameters->options().relocatable())
2546 gold_assert(segment_headers != NULL);
2547 if (header_gap != 0 && load_seg != NULL)
2549 Output_data_zero_fill* z = new Output_data_zero_fill(header_gap, 1);
2550 load_seg->add_initial_output_data(z);
2552 if (load_seg != NULL)
2553 load_seg->add_initial_output_data(segment_headers);
2554 if (phdr_seg != NULL)
2555 phdr_seg->add_initial_output_data(segment_headers);
2558 // Lay out the file header.
2559 if (load_seg != NULL)
2560 load_seg->add_initial_output_data(file_header);
2562 if (this->script_options_->saw_phdrs_clause()
2563 && !parameters->options().relocatable())
2565 // Support use of FILEHDRS and PHDRS attachments in a PHDRS
2566 // clause in a linker script.
2567 Script_sections* ss = this->script_options_->script_sections();
2568 ss->put_headers_in_phdrs(file_header, segment_headers);
2571 // We set the output section indexes in set_segment_offsets and
2572 // set_section_indexes.
2575 // Set the file offsets of all the segments, and all the sections
2578 if (!parameters->options().relocatable())
2579 off = this->set_segment_offsets(target, load_seg, pshndx);
2581 off = this->set_relocatable_section_offsets(file_header, pshndx);
2583 // Verify that the dummy relaxation does not change anything.
2584 if (is_debugging_enabled(DEBUG_RELAXATION))
2587 this->relaxation_debug_check_->read_sections(this->section_list_);
2589 this->relaxation_debug_check_->verify_sections(this->section_list_);
2592 *pload_seg = load_seg;
2596 // Search the list of patterns and find the position of the given section
2597 // name in the output section. If the section name matches a glob
2598 // pattern and a non-glob name, then the non-glob position takes
2599 // precedence. Return 0 if no match is found.
2602 Layout::find_section_order_index(const std::string& section_name)
2604 Unordered_map<std::string, unsigned int>::iterator map_it;
2605 map_it = this->input_section_position_.find(section_name);
2606 if (map_it != this->input_section_position_.end())
2607 return map_it->second;
2609 // Absolute match failed. Linear search the glob patterns.
2610 std::vector<std::string>::iterator it;
2611 for (it = this->input_section_glob_.begin();
2612 it != this->input_section_glob_.end();
2615 if (fnmatch((*it).c_str(), section_name.c_str(), FNM_NOESCAPE) == 0)
2617 map_it = this->input_section_position_.find(*it);
2618 gold_assert(map_it != this->input_section_position_.end());
2619 return map_it->second;
2625 // Read the sequence of input sections from the file specified with
2626 // option --section-ordering-file.
2629 Layout::read_layout_from_file()
2631 const char* filename = parameters->options().section_ordering_file();
2637 gold_fatal(_("unable to open --section-ordering-file file %s: %s"),
2638 filename, strerror(errno));
2640 std::getline(in, line); // this chops off the trailing \n, if any
2641 unsigned int position = 1;
2642 this->set_section_ordering_specified();
2646 if (!line.empty() && line[line.length() - 1] == '\r') // Windows
2647 line.resize(line.length() - 1);
2648 // Ignore comments, beginning with '#'
2651 std::getline(in, line);
2654 this->input_section_position_[line] = position;
2655 // Store all glob patterns in a vector.
2656 if (is_wildcard_string(line.c_str()))
2657 this->input_section_glob_.push_back(line);
2659 std::getline(in, line);
2663 // Finalize the layout. When this is called, we have created all the
2664 // output sections and all the output segments which are based on
2665 // input sections. We have several things to do, and we have to do
2666 // them in the right order, so that we get the right results correctly
2669 // 1) Finalize the list of output segments and create the segment
2672 // 2) Finalize the dynamic symbol table and associated sections.
2674 // 3) Determine the final file offset of all the output segments.
2676 // 4) Determine the final file offset of all the SHF_ALLOC output
2679 // 5) Create the symbol table sections and the section name table
2682 // 6) Finalize the symbol table: set symbol values to their final
2683 // value and make a final determination of which symbols are going
2684 // into the output symbol table.
2686 // 7) Create the section table header.
2688 // 8) Determine the final file offset of all the output sections which
2689 // are not SHF_ALLOC, including the section table header.
2691 // 9) Finalize the ELF file header.
2693 // This function returns the size of the output file.
2696 Layout::finalize(const Input_objects* input_objects, Symbol_table* symtab,
2697 Target* target, const Task* task)
2699 unsigned int local_dynamic_count = 0;
2700 unsigned int forced_local_dynamic_count = 0;
2702 target->finalize_sections(this, input_objects, symtab);
2704 this->count_local_symbols(task, input_objects);
2706 this->link_stabs_sections();
2708 Output_segment* phdr_seg = NULL;
2709 if (!parameters->options().relocatable() && !parameters->doing_static_link())
2711 // There was a dynamic object in the link. We need to create
2712 // some information for the dynamic linker.
2714 // Create the PT_PHDR segment which will hold the program
2716 if (!this->script_options_->saw_phdrs_clause())
2717 phdr_seg = this->make_output_segment(elfcpp::PT_PHDR, elfcpp::PF_R);
2719 // Create the dynamic symbol table, including the hash table.
2720 Output_section* dynstr;
2721 std::vector<Symbol*> dynamic_symbols;
2722 Versions versions(*this->script_options()->version_script_info(),
2724 this->create_dynamic_symtab(input_objects, symtab, &dynstr,
2725 &local_dynamic_count,
2726 &forced_local_dynamic_count,
2730 // Create the .interp section to hold the name of the
2731 // interpreter, and put it in a PT_INTERP segment. Don't do it
2732 // if we saw a .interp section in an input file.
2733 if ((!parameters->options().shared()
2734 || parameters->options().dynamic_linker() != NULL)
2735 && this->interp_segment_ == NULL)
2736 this->create_interp(target);
2738 // Finish the .dynamic section to hold the dynamic data, and put
2739 // it in a PT_DYNAMIC segment.
2740 this->finish_dynamic_section(input_objects, symtab);
2742 // We should have added everything we need to the dynamic string
2744 this->dynpool_.set_string_offsets();
2746 // Create the version sections. We can't do this until the
2747 // dynamic string table is complete.
2748 this->create_version_sections(&versions, symtab,
2749 (local_dynamic_count
2750 + forced_local_dynamic_count),
2751 dynamic_symbols, dynstr);
2753 // Set the size of the _DYNAMIC symbol. We can't do this until
2754 // after we call create_version_sections.
2755 this->set_dynamic_symbol_size(symtab);
2758 // Create segment headers.
2759 Output_segment_headers* segment_headers =
2760 (parameters->options().relocatable()
2762 : new Output_segment_headers(this->segment_list_));
2764 // Lay out the file header.
2765 Output_file_header* file_header = new Output_file_header(target, symtab,
2768 this->special_output_list_.push_back(file_header);
2769 if (segment_headers != NULL)
2770 this->special_output_list_.push_back(segment_headers);
2772 // Find approriate places for orphan output sections if we are using
2774 if (this->script_options_->saw_sections_clause())
2775 this->place_orphan_sections_in_script();
2777 Output_segment* load_seg;
2782 // Take a snapshot of the section layout as needed.
2783 if (target->may_relax())
2784 this->prepare_for_relaxation();
2786 // Run the relaxation loop to lay out sections.
2789 off = this->relaxation_loop_body(pass, target, symtab, &load_seg,
2790 phdr_seg, segment_headers, file_header,
2794 while (target->may_relax()
2795 && target->relax(pass, input_objects, symtab, this, task));
2797 // If there is a load segment that contains the file and program headers,
2798 // provide a symbol __ehdr_start pointing there.
2799 // A program can use this to examine itself robustly.
2800 Symbol *ehdr_start = symtab->lookup("__ehdr_start");
2801 if (ehdr_start != NULL && ehdr_start->is_predefined())
2803 if (load_seg != NULL)
2804 ehdr_start->set_output_segment(load_seg, Symbol::SEGMENT_START);
2806 ehdr_start->set_undefined();
2809 // Set the file offsets of all the non-data sections we've seen so
2810 // far which don't have to wait for the input sections. We need
2811 // this in order to finalize local symbols in non-allocated
2813 off = this->set_section_offsets(off, BEFORE_INPUT_SECTIONS_PASS);
2815 // Set the section indexes of all unallocated sections seen so far,
2816 // in case any of them are somehow referenced by a symbol.
2817 shndx = this->set_section_indexes(shndx);
2819 // Create the symbol table sections.
2820 this->create_symtab_sections(input_objects, symtab, shndx, &off,
2821 local_dynamic_count);
2822 if (!parameters->doing_static_link())
2823 this->assign_local_dynsym_offsets(input_objects);
2825 // Process any symbol assignments from a linker script. This must
2826 // be called after the symbol table has been finalized.
2827 this->script_options_->finalize_symbols(symtab, this);
2829 // Create the incremental inputs sections.
2830 if (this->incremental_inputs_)
2832 this->incremental_inputs_->finalize();
2833 this->create_incremental_info_sections(symtab);
2836 // Create the .shstrtab section.
2837 Output_section* shstrtab_section = this->create_shstrtab();
2839 // Set the file offsets of the rest of the non-data sections which
2840 // don't have to wait for the input sections.
2841 off = this->set_section_offsets(off, BEFORE_INPUT_SECTIONS_PASS);
2843 // Now that all sections have been created, set the section indexes
2844 // for any sections which haven't been done yet.
2845 shndx = this->set_section_indexes(shndx);
2847 // Create the section table header.
2848 this->create_shdrs(shstrtab_section, &off);
2850 // If there are no sections which require postprocessing, we can
2851 // handle the section names now, and avoid a resize later.
2852 if (!this->any_postprocessing_sections_)
2854 off = this->set_section_offsets(off,
2855 POSTPROCESSING_SECTIONS_PASS);
2857 this->set_section_offsets(off,
2858 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS);
2861 file_header->set_section_info(this->section_headers_, shstrtab_section);
2863 // Now we know exactly where everything goes in the output file
2864 // (except for non-allocated sections which require postprocessing).
2865 Output_data::layout_complete();
2867 this->output_file_size_ = off;
2872 // Create a note header following the format defined in the ELF ABI.
2873 // NAME is the name, NOTE_TYPE is the type, SECTION_NAME is the name
2874 // of the section to create, DESCSZ is the size of the descriptor.
2875 // ALLOCATE is true if the section should be allocated in memory.
2876 // This returns the new note section. It sets *TRAILING_PADDING to
2877 // the number of trailing zero bytes required.
2880 Layout::create_note(const char* name, int note_type,
2881 const char* section_name, size_t descsz,
2882 bool allocate, size_t* trailing_padding)
2884 // Authorities all agree that the values in a .note field should
2885 // be aligned on 4-byte boundaries for 32-bit binaries. However,
2886 // they differ on what the alignment is for 64-bit binaries.
2887 // The GABI says unambiguously they take 8-byte alignment:
2888 // http://sco.com/developers/gabi/latest/ch5.pheader.html#note_section
2889 // Other documentation says alignment should always be 4 bytes:
2890 // http://www.netbsd.org/docs/kernel/elf-notes.html#note-format
2891 // GNU ld and GNU readelf both support the latter (at least as of
2892 // version 2.16.91), and glibc always generates the latter for
2893 // .note.ABI-tag (as of version 1.6), so that's the one we go with
2895 #ifdef GABI_FORMAT_FOR_DOTNOTE_SECTION // This is not defined by default.
2896 const int size = parameters->target().get_size();
2898 const int size = 32;
2901 // The contents of the .note section.
2902 size_t namesz = strlen(name) + 1;
2903 size_t aligned_namesz = align_address(namesz, size / 8);
2904 size_t aligned_descsz = align_address(descsz, size / 8);
2906 size_t notehdrsz = 3 * (size / 8) + aligned_namesz;
2908 unsigned char* buffer = new unsigned char[notehdrsz];
2909 memset(buffer, 0, notehdrsz);
2911 bool is_big_endian = parameters->target().is_big_endian();
2917 elfcpp::Swap<32, false>::writeval(buffer, namesz);
2918 elfcpp::Swap<32, false>::writeval(buffer + 4, descsz);
2919 elfcpp::Swap<32, false>::writeval(buffer + 8, note_type);
2923 elfcpp::Swap<32, true>::writeval(buffer, namesz);
2924 elfcpp::Swap<32, true>::writeval(buffer + 4, descsz);
2925 elfcpp::Swap<32, true>::writeval(buffer + 8, note_type);
2928 else if (size == 64)
2932 elfcpp::Swap<64, false>::writeval(buffer, namesz);
2933 elfcpp::Swap<64, false>::writeval(buffer + 8, descsz);
2934 elfcpp::Swap<64, false>::writeval(buffer + 16, note_type);
2938 elfcpp::Swap<64, true>::writeval(buffer, namesz);
2939 elfcpp::Swap<64, true>::writeval(buffer + 8, descsz);
2940 elfcpp::Swap<64, true>::writeval(buffer + 16, note_type);
2946 memcpy(buffer + 3 * (size / 8), name, namesz);
2948 elfcpp::Elf_Xword flags = 0;
2949 Output_section_order order = ORDER_INVALID;
2952 flags = elfcpp::SHF_ALLOC;
2953 order = ORDER_RO_NOTE;
2955 Output_section* os = this->choose_output_section(NULL, section_name,
2957 flags, false, order, false,
2962 Output_section_data* posd = new Output_data_const_buffer(buffer, notehdrsz,
2965 os->add_output_section_data(posd);
2967 *trailing_padding = aligned_descsz - descsz;
2972 // For an executable or shared library, create a note to record the
2973 // version of gold used to create the binary.
2976 Layout::create_gold_note()
2978 if (parameters->options().relocatable()
2979 || parameters->incremental_update())
2982 std::string desc = std::string("gold ") + gold::get_version_string();
2984 size_t trailing_padding;
2985 Output_section* os = this->create_note("GNU", elfcpp::NT_GNU_GOLD_VERSION,
2986 ".note.gnu.gold-version", desc.size(),
2987 false, &trailing_padding);
2991 Output_section_data* posd = new Output_data_const(desc, 4);
2992 os->add_output_section_data(posd);
2994 if (trailing_padding > 0)
2996 posd = new Output_data_zero_fill(trailing_padding, 0);
2997 os->add_output_section_data(posd);
3001 // Record whether the stack should be executable. This can be set
3002 // from the command line using the -z execstack or -z noexecstack
3003 // options. Otherwise, if any input file has a .note.GNU-stack
3004 // section with the SHF_EXECINSTR flag set, the stack should be
3005 // executable. Otherwise, if at least one input file a
3006 // .note.GNU-stack section, and some input file has no .note.GNU-stack
3007 // section, we use the target default for whether the stack should be
3008 // executable. If -z stack-size was used to set a p_memsz value for
3009 // PT_GNU_STACK, we generate the segment regardless. Otherwise, we
3010 // don't generate a stack note. When generating a object file, we
3011 // create a .note.GNU-stack section with the appropriate marking.
3012 // When generating an executable or shared library, we create a
3013 // PT_GNU_STACK segment.
3016 Layout::create_stack_segment()
3018 bool is_stack_executable;
3019 if (parameters->options().is_execstack_set())
3021 is_stack_executable = parameters->options().is_stack_executable();
3022 if (!is_stack_executable
3023 && this->input_requires_executable_stack_
3024 && parameters->options().warn_execstack())
3025 gold_warning(_("one or more inputs require executable stack, "
3026 "but -z noexecstack was given"));
3028 else if (!this->input_with_gnu_stack_note_
3029 && (!parameters->options().user_set_stack_size()
3030 || parameters->options().relocatable()))
3034 if (this->input_requires_executable_stack_)
3035 is_stack_executable = true;
3036 else if (this->input_without_gnu_stack_note_)
3037 is_stack_executable =
3038 parameters->target().is_default_stack_executable();
3040 is_stack_executable = false;
3043 if (parameters->options().relocatable())
3045 const char* name = this->namepool_.add(".note.GNU-stack", false, NULL);
3046 elfcpp::Elf_Xword flags = 0;
3047 if (is_stack_executable)
3048 flags |= elfcpp::SHF_EXECINSTR;
3049 this->make_output_section(name, elfcpp::SHT_PROGBITS, flags,
3050 ORDER_INVALID, false);
3054 if (this->script_options_->saw_phdrs_clause())
3056 int flags = elfcpp::PF_R | elfcpp::PF_W;
3057 if (is_stack_executable)
3058 flags |= elfcpp::PF_X;
3059 Output_segment* seg =
3060 this->make_output_segment(elfcpp::PT_GNU_STACK, flags);
3061 seg->set_size(parameters->options().stack_size());
3062 // BFD lets targets override this default alignment, but the only
3063 // targets that do so are ones that Gold does not support so far.
3064 seg->set_minimum_p_align(16);
3068 // If --build-id was used, set up the build ID note.
3071 Layout::create_build_id()
3073 if (!parameters->options().user_set_build_id())
3076 const char* style = parameters->options().build_id();
3077 if (strcmp(style, "none") == 0)
3080 // Set DESCSZ to the size of the note descriptor. When possible,
3081 // set DESC to the note descriptor contents.
3084 if (strcmp(style, "md5") == 0)
3086 else if ((strcmp(style, "sha1") == 0) || (strcmp(style, "tree") == 0))
3088 else if (strcmp(style, "uuid") == 0)
3091 const size_t uuidsz = 128 / 8;
3093 char buffer[uuidsz];
3094 memset(buffer, 0, uuidsz);
3096 int descriptor = open_descriptor(-1, "/dev/urandom", O_RDONLY);
3098 gold_error(_("--build-id=uuid failed: could not open /dev/urandom: %s"),
3102 ssize_t got = ::read(descriptor, buffer, uuidsz);
3103 release_descriptor(descriptor, true);
3105 gold_error(_("/dev/urandom: read failed: %s"), strerror(errno));
3106 else if (static_cast<size_t>(got) != uuidsz)
3107 gold_error(_("/dev/urandom: expected %zu bytes, got %zd bytes"),
3111 desc.assign(buffer, uuidsz);
3113 #else // __MINGW32__
3115 typedef RPC_STATUS (RPC_ENTRY *UuidCreateFn)(UUID *Uuid);
3117 HMODULE rpc_library = LoadLibrary("rpcrt4.dll");
3119 gold_error(_("--build-id=uuid failed: could not load rpcrt4.dll"));
3122 UuidCreateFn uuid_create = reinterpret_cast<UuidCreateFn>(
3123 GetProcAddress(rpc_library, "UuidCreate"));
3125 gold_error(_("--build-id=uuid failed: could not find UuidCreate"));
3126 else if (uuid_create(&uuid) != RPC_S_OK)
3127 gold_error(_("__build_id=uuid failed: call UuidCreate() failed"));
3128 FreeLibrary(rpc_library);
3130 desc.assign(reinterpret_cast<const char *>(&uuid), sizeof(UUID));
3131 descsz = sizeof(UUID);
3132 #endif // __MINGW32__
3134 else if (strncmp(style, "0x", 2) == 0)
3137 const char* p = style + 2;
3140 if (hex_p(p[0]) && hex_p(p[1]))
3142 char c = (hex_value(p[0]) << 4) | hex_value(p[1]);
3146 else if (*p == '-' || *p == ':')
3149 gold_fatal(_("--build-id argument '%s' not a valid hex number"),
3152 descsz = desc.size();
3155 gold_fatal(_("unrecognized --build-id argument '%s'"), style);
3158 size_t trailing_padding;
3159 Output_section* os = this->create_note("GNU", elfcpp::NT_GNU_BUILD_ID,
3160 ".note.gnu.build-id", descsz, true,
3167 // We know the value already, so we fill it in now.
3168 gold_assert(desc.size() == descsz);
3170 Output_section_data* posd = new Output_data_const(desc, 4);
3171 os->add_output_section_data(posd);
3173 if (trailing_padding != 0)
3175 posd = new Output_data_zero_fill(trailing_padding, 0);
3176 os->add_output_section_data(posd);
3181 // We need to compute a checksum after we have completed the
3183 gold_assert(trailing_padding == 0);
3184 this->build_id_note_ = new Output_data_zero_fill(descsz, 4);
3185 os->add_output_section_data(this->build_id_note_);
3189 // If we have both .stabXX and .stabXXstr sections, then the sh_link
3190 // field of the former should point to the latter. I'm not sure who
3191 // started this, but the GNU linker does it, and some tools depend
3195 Layout::link_stabs_sections()
3197 if (!this->have_stabstr_section_)
3200 for (Section_list::iterator p = this->section_list_.begin();
3201 p != this->section_list_.end();
3204 if ((*p)->type() != elfcpp::SHT_STRTAB)
3207 const char* name = (*p)->name();
3208 if (strncmp(name, ".stab", 5) != 0)
3211 size_t len = strlen(name);
3212 if (strcmp(name + len - 3, "str") != 0)
3215 std::string stab_name(name, len - 3);
3216 Output_section* stab_sec;
3217 stab_sec = this->find_output_section(stab_name.c_str());
3218 if (stab_sec != NULL)
3219 stab_sec->set_link_section(*p);
3223 // Create .gnu_incremental_inputs and related sections needed
3224 // for the next run of incremental linking to check what has changed.
3227 Layout::create_incremental_info_sections(Symbol_table* symtab)
3229 Incremental_inputs* incr = this->incremental_inputs_;
3231 gold_assert(incr != NULL);
3233 // Create the .gnu_incremental_inputs, _symtab, and _relocs input sections.
3234 incr->create_data_sections(symtab);
3236 // Add the .gnu_incremental_inputs section.
3237 const char* incremental_inputs_name =
3238 this->namepool_.add(".gnu_incremental_inputs", false, NULL);
3239 Output_section* incremental_inputs_os =
3240 this->make_output_section(incremental_inputs_name,
3241 elfcpp::SHT_GNU_INCREMENTAL_INPUTS, 0,
3242 ORDER_INVALID, false);
3243 incremental_inputs_os->add_output_section_data(incr->inputs_section());
3245 // Add the .gnu_incremental_symtab section.
3246 const char* incremental_symtab_name =
3247 this->namepool_.add(".gnu_incremental_symtab", false, NULL);
3248 Output_section* incremental_symtab_os =
3249 this->make_output_section(incremental_symtab_name,
3250 elfcpp::SHT_GNU_INCREMENTAL_SYMTAB, 0,
3251 ORDER_INVALID, false);
3252 incremental_symtab_os->add_output_section_data(incr->symtab_section());
3253 incremental_symtab_os->set_entsize(4);
3255 // Add the .gnu_incremental_relocs section.
3256 const char* incremental_relocs_name =
3257 this->namepool_.add(".gnu_incremental_relocs", false, NULL);
3258 Output_section* incremental_relocs_os =
3259 this->make_output_section(incremental_relocs_name,
3260 elfcpp::SHT_GNU_INCREMENTAL_RELOCS, 0,
3261 ORDER_INVALID, false);
3262 incremental_relocs_os->add_output_section_data(incr->relocs_section());
3263 incremental_relocs_os->set_entsize(incr->relocs_entsize());
3265 // Add the .gnu_incremental_got_plt section.
3266 const char* incremental_got_plt_name =
3267 this->namepool_.add(".gnu_incremental_got_plt", false, NULL);
3268 Output_section* incremental_got_plt_os =
3269 this->make_output_section(incremental_got_plt_name,
3270 elfcpp::SHT_GNU_INCREMENTAL_GOT_PLT, 0,
3271 ORDER_INVALID, false);
3272 incremental_got_plt_os->add_output_section_data(incr->got_plt_section());
3274 // Add the .gnu_incremental_strtab section.
3275 const char* incremental_strtab_name =
3276 this->namepool_.add(".gnu_incremental_strtab", false, NULL);
3277 Output_section* incremental_strtab_os = this->make_output_section(incremental_strtab_name,
3278 elfcpp::SHT_STRTAB, 0,
3279 ORDER_INVALID, false);
3280 Output_data_strtab* strtab_data =
3281 new Output_data_strtab(incr->get_stringpool());
3282 incremental_strtab_os->add_output_section_data(strtab_data);
3284 incremental_inputs_os->set_after_input_sections();
3285 incremental_symtab_os->set_after_input_sections();
3286 incremental_relocs_os->set_after_input_sections();
3287 incremental_got_plt_os->set_after_input_sections();
3289 incremental_inputs_os->set_link_section(incremental_strtab_os);
3290 incremental_symtab_os->set_link_section(incremental_inputs_os);
3291 incremental_relocs_os->set_link_section(incremental_inputs_os);
3292 incremental_got_plt_os->set_link_section(incremental_inputs_os);
3295 // Return whether SEG1 should be before SEG2 in the output file. This
3296 // is based entirely on the segment type and flags. When this is
3297 // called the segment addresses have normally not yet been set.
3300 Layout::segment_precedes(const Output_segment* seg1,
3301 const Output_segment* seg2)
3303 elfcpp::Elf_Word type1 = seg1->type();
3304 elfcpp::Elf_Word type2 = seg2->type();
3306 // The single PT_PHDR segment is required to precede any loadable
3307 // segment. We simply make it always first.
3308 if (type1 == elfcpp::PT_PHDR)
3310 gold_assert(type2 != elfcpp::PT_PHDR);
3313 if (type2 == elfcpp::PT_PHDR)
3316 // The single PT_INTERP segment is required to precede any loadable
3317 // segment. We simply make it always second.
3318 if (type1 == elfcpp::PT_INTERP)
3320 gold_assert(type2 != elfcpp::PT_INTERP);
3323 if (type2 == elfcpp::PT_INTERP)
3326 // We then put PT_LOAD segments before any other segments.
3327 if (type1 == elfcpp::PT_LOAD && type2 != elfcpp::PT_LOAD)
3329 if (type2 == elfcpp::PT_LOAD && type1 != elfcpp::PT_LOAD)
3332 // We put the PT_TLS segment last except for the PT_GNU_RELRO
3333 // segment, because that is where the dynamic linker expects to find
3334 // it (this is just for efficiency; other positions would also work
3336 if (type1 == elfcpp::PT_TLS
3337 && type2 != elfcpp::PT_TLS
3338 && type2 != elfcpp::PT_GNU_RELRO)
3340 if (type2 == elfcpp::PT_TLS
3341 && type1 != elfcpp::PT_TLS
3342 && type1 != elfcpp::PT_GNU_RELRO)
3345 // We put the PT_GNU_RELRO segment last, because that is where the
3346 // dynamic linker expects to find it (as with PT_TLS, this is just
3348 if (type1 == elfcpp::PT_GNU_RELRO && type2 != elfcpp::PT_GNU_RELRO)
3350 if (type2 == elfcpp::PT_GNU_RELRO && type1 != elfcpp::PT_GNU_RELRO)
3353 const elfcpp::Elf_Word flags1 = seg1->flags();
3354 const elfcpp::Elf_Word flags2 = seg2->flags();
3356 // The order of non-PT_LOAD segments is unimportant. We simply sort
3357 // by the numeric segment type and flags values. There should not
3358 // be more than one segment with the same type and flags, except
3359 // when a linker script specifies such.
3360 if (type1 != elfcpp::PT_LOAD)
3363 return type1 < type2;
3364 gold_assert(flags1 != flags2
3365 || this->script_options_->saw_phdrs_clause());
3366 return flags1 < flags2;
3369 // If the addresses are set already, sort by load address.
3370 if (seg1->are_addresses_set())
3372 if (!seg2->are_addresses_set())
3375 unsigned int section_count1 = seg1->output_section_count();
3376 unsigned int section_count2 = seg2->output_section_count();
3377 if (section_count1 == 0 && section_count2 > 0)
3379 if (section_count1 > 0 && section_count2 == 0)
3382 uint64_t paddr1 = (seg1->are_addresses_set()
3384 : seg1->first_section_load_address());
3385 uint64_t paddr2 = (seg2->are_addresses_set()
3387 : seg2->first_section_load_address());
3389 if (paddr1 != paddr2)
3390 return paddr1 < paddr2;
3392 else if (seg2->are_addresses_set())
3395 // A segment which holds large data comes after a segment which does
3396 // not hold large data.
3397 if (seg1->is_large_data_segment())
3399 if (!seg2->is_large_data_segment())
3402 else if (seg2->is_large_data_segment())
3405 // Otherwise, we sort PT_LOAD segments based on the flags. Readonly
3406 // segments come before writable segments. Then writable segments
3407 // with data come before writable segments without data. Then
3408 // executable segments come before non-executable segments. Then
3409 // the unlikely case of a non-readable segment comes before the
3410 // normal case of a readable segment. If there are multiple
3411 // segments with the same type and flags, we require that the
3412 // address be set, and we sort by virtual address and then physical
3414 if ((flags1 & elfcpp::PF_W) != (flags2 & elfcpp::PF_W))
3415 return (flags1 & elfcpp::PF_W) == 0;
3416 if ((flags1 & elfcpp::PF_W) != 0
3417 && seg1->has_any_data_sections() != seg2->has_any_data_sections())
3418 return seg1->has_any_data_sections();
3419 if ((flags1 & elfcpp::PF_X) != (flags2 & elfcpp::PF_X))
3420 return (flags1 & elfcpp::PF_X) != 0;
3421 if ((flags1 & elfcpp::PF_R) != (flags2 & elfcpp::PF_R))
3422 return (flags1 & elfcpp::PF_R) == 0;
3424 // We shouldn't get here--we shouldn't create segments which we
3425 // can't distinguish. Unless of course we are using a weird linker
3426 // script or overlapping --section-start options. We could also get
3427 // here if plugins want unique segments for subsets of sections.
3428 gold_assert(this->script_options_->saw_phdrs_clause()
3429 || parameters->options().any_section_start()
3430 || this->is_unique_segment_for_sections_specified());
3434 // Increase OFF so that it is congruent to ADDR modulo ABI_PAGESIZE.
3437 align_file_offset(off_t off, uint64_t addr, uint64_t abi_pagesize)
3439 uint64_t unsigned_off = off;
3440 uint64_t aligned_off = ((unsigned_off & ~(abi_pagesize - 1))
3441 | (addr & (abi_pagesize - 1)));
3442 if (aligned_off < unsigned_off)
3443 aligned_off += abi_pagesize;
3447 // On targets where the text segment contains only executable code,
3448 // a non-executable segment is never the text segment.
3451 is_text_segment(const Target* target, const Output_segment* seg)
3453 elfcpp::Elf_Xword flags = seg->flags();
3454 if ((flags & elfcpp::PF_W) != 0)
3456 if ((flags & elfcpp::PF_X) == 0)
3457 return !target->isolate_execinstr();
3461 // Set the file offsets of all the segments, and all the sections they
3462 // contain. They have all been created. LOAD_SEG must be be laid out
3463 // first. Return the offset of the data to follow.
3466 Layout::set_segment_offsets(const Target* target, Output_segment* load_seg,
3467 unsigned int* pshndx)
3469 // Sort them into the final order. We use a stable sort so that we
3470 // don't randomize the order of indistinguishable segments created
3471 // by linker scripts.
3472 std::stable_sort(this->segment_list_.begin(), this->segment_list_.end(),
3473 Layout::Compare_segments(this));
3475 // Find the PT_LOAD segments, and set their addresses and offsets
3476 // and their section's addresses and offsets.
3477 uint64_t start_addr;
3478 if (parameters->options().user_set_Ttext())
3479 start_addr = parameters->options().Ttext();
3480 else if (parameters->options().output_is_position_independent())
3483 start_addr = target->default_text_segment_address();
3485 uint64_t addr = start_addr;
3488 // If LOAD_SEG is NULL, then the file header and segment headers
3489 // will not be loadable. But they still need to be at offset 0 in
3490 // the file. Set their offsets now.
3491 if (load_seg == NULL)
3493 for (Data_list::iterator p = this->special_output_list_.begin();
3494 p != this->special_output_list_.end();
3497 off = align_address(off, (*p)->addralign());
3498 (*p)->set_address_and_file_offset(0, off);
3499 off += (*p)->data_size();
3503 unsigned int increase_relro = this->increase_relro_;
3504 if (this->script_options_->saw_sections_clause())
3507 const bool check_sections = parameters->options().check_sections();
3508 Output_segment* last_load_segment = NULL;
3510 unsigned int shndx_begin = *pshndx;
3511 unsigned int shndx_load_seg = *pshndx;
3513 for (Segment_list::iterator p = this->segment_list_.begin();
3514 p != this->segment_list_.end();
3517 if ((*p)->type() == elfcpp::PT_LOAD)
3519 if (target->isolate_execinstr())
3521 // When we hit the segment that should contain the
3522 // file headers, reset the file offset so we place
3523 // it and subsequent segments appropriately.
3524 // We'll fix up the preceding segments below.
3532 shndx_load_seg = *pshndx;
3538 // Verify that the file headers fall into the first segment.
3539 if (load_seg != NULL && load_seg != *p)
3544 bool are_addresses_set = (*p)->are_addresses_set();
3545 if (are_addresses_set)
3547 // When it comes to setting file offsets, we care about
3548 // the physical address.
3549 addr = (*p)->paddr();
3551 else if (parameters->options().user_set_Ttext()
3552 && (parameters->options().omagic()
3553 || is_text_segment(target, *p)))
3555 are_addresses_set = true;
3557 else if (parameters->options().user_set_Trodata_segment()
3558 && ((*p)->flags() & (elfcpp::PF_W | elfcpp::PF_X)) == 0)
3560 addr = parameters->options().Trodata_segment();
3561 are_addresses_set = true;
3563 else if (parameters->options().user_set_Tdata()
3564 && ((*p)->flags() & elfcpp::PF_W) != 0
3565 && (!parameters->options().user_set_Tbss()
3566 || (*p)->has_any_data_sections()))
3568 addr = parameters->options().Tdata();
3569 are_addresses_set = true;
3571 else if (parameters->options().user_set_Tbss()
3572 && ((*p)->flags() & elfcpp::PF_W) != 0
3573 && !(*p)->has_any_data_sections())
3575 addr = parameters->options().Tbss();
3576 are_addresses_set = true;
3579 uint64_t orig_addr = addr;
3580 uint64_t orig_off = off;
3582 uint64_t aligned_addr = 0;
3583 uint64_t abi_pagesize = target->abi_pagesize();
3584 uint64_t common_pagesize = target->common_pagesize();
3586 if (!parameters->options().nmagic()
3587 && !parameters->options().omagic())
3588 (*p)->set_minimum_p_align(abi_pagesize);
3590 if (!are_addresses_set)
3592 // Skip the address forward one page, maintaining the same
3593 // position within the page. This lets us store both segments
3594 // overlapping on a single page in the file, but the loader will
3595 // put them on different pages in memory. We will revisit this
3596 // decision once we know the size of the segment.
3598 uint64_t max_align = (*p)->maximum_alignment();
3599 if (max_align > abi_pagesize)
3600 addr = align_address(addr, max_align);
3601 aligned_addr = addr;
3605 // This is the segment that will contain the file
3606 // headers, so its offset will have to be exactly zero.
3607 gold_assert(orig_off == 0);
3609 // If the target wants a fixed minimum distance from the
3610 // text segment to the read-only segment, move up now.
3612 start_addr + (parameters->options().user_set_rosegment_gap()
3613 ? parameters->options().rosegment_gap()
3614 : target->rosegment_gap());
3615 if (addr < min_addr)
3618 // But this is not the first segment! To make its
3619 // address congruent with its offset, that address better
3620 // be aligned to the ABI-mandated page size.
3621 addr = align_address(addr, abi_pagesize);
3622 aligned_addr = addr;
3626 if ((addr & (abi_pagesize - 1)) != 0)
3627 addr = addr + abi_pagesize;
3629 off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
3633 if (!parameters->options().nmagic()
3634 && !parameters->options().omagic())
3636 // Here we are also taking care of the case when
3637 // the maximum segment alignment is larger than the page size.
3638 off = align_file_offset(off, addr,
3639 std::max(abi_pagesize,
3640 (*p)->maximum_alignment()));
3644 // This is -N or -n with a section script which prevents
3645 // us from using a load segment. We need to ensure that
3646 // the file offset is aligned to the alignment of the
3647 // segment. This is because the linker script
3648 // implicitly assumed a zero offset. If we don't align
3649 // here, then the alignment of the sections in the
3650 // linker script may not match the alignment of the
3651 // sections in the set_section_addresses call below,
3652 // causing an error about dot moving backward.
3653 off = align_address(off, (*p)->maximum_alignment());
3656 unsigned int shndx_hold = *pshndx;
3657 bool has_relro = false;
3658 uint64_t new_addr = (*p)->set_section_addresses(target, this,
3664 // Now that we know the size of this segment, we may be able
3665 // to save a page in memory, at the cost of wasting some
3666 // file space, by instead aligning to the start of a new
3667 // page. Here we use the real machine page size rather than
3668 // the ABI mandated page size. If the segment has been
3669 // aligned so that the relro data ends at a page boundary,
3670 // we do not try to realign it.
3672 if (!are_addresses_set
3674 && aligned_addr != addr
3675 && !parameters->incremental())
3677 uint64_t first_off = (common_pagesize
3679 & (common_pagesize - 1)));
3680 uint64_t last_off = new_addr & (common_pagesize - 1);
3683 && ((aligned_addr & ~ (common_pagesize - 1))
3684 != (new_addr & ~ (common_pagesize - 1)))
3685 && first_off + last_off <= common_pagesize)
3687 *pshndx = shndx_hold;
3688 addr = align_address(aligned_addr, common_pagesize);
3689 addr = align_address(addr, (*p)->maximum_alignment());
3690 if ((addr & (abi_pagesize - 1)) != 0)
3691 addr = addr + abi_pagesize;
3692 off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
3693 off = align_file_offset(off, addr, abi_pagesize);
3695 increase_relro = this->increase_relro_;
3696 if (this->script_options_->saw_sections_clause())
3700 new_addr = (*p)->set_section_addresses(target, this,
3710 // Implement --check-sections. We know that the segments
3711 // are sorted by LMA.
3712 if (check_sections && last_load_segment != NULL)
3714 gold_assert(last_load_segment->paddr() <= (*p)->paddr());
3715 if (last_load_segment->paddr() + last_load_segment->memsz()
3718 unsigned long long lb1 = last_load_segment->paddr();
3719 unsigned long long le1 = lb1 + last_load_segment->memsz();
3720 unsigned long long lb2 = (*p)->paddr();
3721 unsigned long long le2 = lb2 + (*p)->memsz();
3722 gold_error(_("load segment overlap [0x%llx -> 0x%llx] and "
3723 "[0x%llx -> 0x%llx]"),
3724 lb1, le1, lb2, le2);
3727 last_load_segment = *p;
3731 if (load_seg != NULL && target->isolate_execinstr())
3733 // Process the early segments again, setting their file offsets
3734 // so they land after the segments starting at LOAD_SEG.
3735 off = align_file_offset(off, 0, target->abi_pagesize());
3737 this->reset_relax_output();
3739 for (Segment_list::iterator p = this->segment_list_.begin();
3743 if ((*p)->type() == elfcpp::PT_LOAD)
3745 // We repeat the whole job of assigning addresses and
3746 // offsets, but we really only want to change the offsets and
3747 // must ensure that the addresses all come out the same as
3748 // they did the first time through.
3749 bool has_relro = false;
3750 const uint64_t old_addr = (*p)->vaddr();
3751 const uint64_t old_end = old_addr + (*p)->memsz();
3752 uint64_t new_addr = (*p)->set_section_addresses(target, this,
3758 gold_assert(new_addr == old_end);
3762 gold_assert(shndx_begin == shndx_load_seg);
3765 // Handle the non-PT_LOAD segments, setting their offsets from their
3766 // section's offsets.
3767 for (Segment_list::iterator p = this->segment_list_.begin();
3768 p != this->segment_list_.end();
3771 // PT_GNU_STACK was set up correctly when it was created.
3772 if ((*p)->type() != elfcpp::PT_LOAD
3773 && (*p)->type() != elfcpp::PT_GNU_STACK)
3774 (*p)->set_offset((*p)->type() == elfcpp::PT_GNU_RELRO
3779 // Set the TLS offsets for each section in the PT_TLS segment.
3780 if (this->tls_segment_ != NULL)
3781 this->tls_segment_->set_tls_offsets();
3786 // Set the offsets of all the allocated sections when doing a
3787 // relocatable link. This does the same jobs as set_segment_offsets,
3788 // only for a relocatable link.
3791 Layout::set_relocatable_section_offsets(Output_data* file_header,
3792 unsigned int* pshndx)
3796 file_header->set_address_and_file_offset(0, 0);
3797 off += file_header->data_size();
3799 for (Section_list::iterator p = this->section_list_.begin();
3800 p != this->section_list_.end();
3803 // We skip unallocated sections here, except that group sections
3804 // have to come first.
3805 if (((*p)->flags() & elfcpp::SHF_ALLOC) == 0
3806 && (*p)->type() != elfcpp::SHT_GROUP)
3809 off = align_address(off, (*p)->addralign());
3811 // The linker script might have set the address.
3812 if (!(*p)->is_address_valid())
3813 (*p)->set_address(0);
3814 (*p)->set_file_offset(off);
3815 (*p)->finalize_data_size();
3816 if ((*p)->type() != elfcpp::SHT_NOBITS)
3817 off += (*p)->data_size();
3819 (*p)->set_out_shndx(*pshndx);
3826 // Set the file offset of all the sections not associated with a
3830 Layout::set_section_offsets(off_t off, Layout::Section_offset_pass pass)
3832 off_t startoff = off;
3835 for (Section_list::iterator p = this->unattached_section_list_.begin();
3836 p != this->unattached_section_list_.end();
3839 // The symtab section is handled in create_symtab_sections.
3840 if (*p == this->symtab_section_)
3843 // If we've already set the data size, don't set it again.
3844 if ((*p)->is_offset_valid() && (*p)->is_data_size_valid())
3847 if (pass == BEFORE_INPUT_SECTIONS_PASS
3848 && (*p)->requires_postprocessing())
3850 (*p)->create_postprocessing_buffer();
3851 this->any_postprocessing_sections_ = true;
3854 if (pass == BEFORE_INPUT_SECTIONS_PASS
3855 && (*p)->after_input_sections())
3857 else if (pass == POSTPROCESSING_SECTIONS_PASS
3858 && (!(*p)->after_input_sections()
3859 || (*p)->type() == elfcpp::SHT_STRTAB))
3861 else if (pass == STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
3862 && (!(*p)->after_input_sections()
3863 || (*p)->type() != elfcpp::SHT_STRTAB))
3866 if (!parameters->incremental_update())
3868 off = align_address(off, (*p)->addralign());
3869 (*p)->set_file_offset(off);
3870 (*p)->finalize_data_size();
3874 // Incremental update: allocate file space from free list.
3875 (*p)->pre_finalize_data_size();
3876 off_t current_size = (*p)->current_data_size();
3877 off = this->allocate(current_size, (*p)->addralign(), startoff);
3880 if (is_debugging_enabled(DEBUG_INCREMENTAL))
3881 this->free_list_.dump();
3882 gold_assert((*p)->output_section() != NULL);
3883 gold_fallback(_("out of patch space for section %s; "
3884 "relink with --incremental-full"),
3885 (*p)->output_section()->name());
3887 (*p)->set_file_offset(off);
3888 (*p)->finalize_data_size();
3889 if ((*p)->data_size() > current_size)
3891 gold_assert((*p)->output_section() != NULL);
3892 gold_fallback(_("%s: section changed size; "
3893 "relink with --incremental-full"),
3894 (*p)->output_section()->name());
3896 gold_debug(DEBUG_INCREMENTAL,
3897 "set_section_offsets: %08lx %08lx %s",
3898 static_cast<long>(off),
3899 static_cast<long>((*p)->data_size()),
3900 ((*p)->output_section() != NULL
3901 ? (*p)->output_section()->name() : "(special)"));
3904 off += (*p)->data_size();
3908 // At this point the name must be set.
3909 if (pass != STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS)
3910 this->namepool_.add((*p)->name(), false, NULL);
3915 // Set the section indexes of all the sections not associated with a
3919 Layout::set_section_indexes(unsigned int shndx)
3921 for (Section_list::iterator p = this->unattached_section_list_.begin();
3922 p != this->unattached_section_list_.end();
3925 if (!(*p)->has_out_shndx())
3927 (*p)->set_out_shndx(shndx);
3934 // Set the section addresses according to the linker script. This is
3935 // only called when we see a SECTIONS clause. This returns the
3936 // program segment which should hold the file header and segment
3937 // headers, if any. It will return NULL if they should not be in a
3941 Layout::set_section_addresses_from_script(Symbol_table* symtab)
3943 Script_sections* ss = this->script_options_->script_sections();
3944 gold_assert(ss->saw_sections_clause());
3945 return this->script_options_->set_section_addresses(symtab, this);
3948 // Place the orphan sections in the linker script.
3951 Layout::place_orphan_sections_in_script()
3953 Script_sections* ss = this->script_options_->script_sections();
3954 gold_assert(ss->saw_sections_clause());
3956 // Place each orphaned output section in the script.
3957 for (Section_list::iterator p = this->section_list_.begin();
3958 p != this->section_list_.end();
3961 if (!(*p)->found_in_sections_clause())
3962 ss->place_orphan(*p);
3966 // Count the local symbols in the regular symbol table and the dynamic
3967 // symbol table, and build the respective string pools.
3970 Layout::count_local_symbols(const Task* task,
3971 const Input_objects* input_objects)
3973 // First, figure out an upper bound on the number of symbols we'll
3974 // be inserting into each pool. This helps us create the pools with
3975 // the right size, to avoid unnecessary hashtable resizing.
3976 unsigned int symbol_count = 0;
3977 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
3978 p != input_objects->relobj_end();
3980 symbol_count += (*p)->local_symbol_count();
3982 // Go from "upper bound" to "estimate." We overcount for two
3983 // reasons: we double-count symbols that occur in more than one
3984 // object file, and we count symbols that are dropped from the
3985 // output. Add it all together and assume we overcount by 100%.
3988 // We assume all symbols will go into both the sympool and dynpool.
3989 this->sympool_.reserve(symbol_count);
3990 this->dynpool_.reserve(symbol_count);
3992 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
3993 p != input_objects->relobj_end();
3996 Task_lock_obj<Object> tlo(task, *p);
3997 (*p)->count_local_symbols(&this->sympool_, &this->dynpool_);
4001 // Create the symbol table sections. Here we also set the final
4002 // values of the symbols. At this point all the loadable sections are
4003 // fully laid out. SHNUM is the number of sections so far.
4006 Layout::create_symtab_sections(const Input_objects* input_objects,
4007 Symbol_table* symtab,
4010 unsigned int local_dynamic_count)
4014 if (parameters->target().get_size() == 32)
4016 symsize = elfcpp::Elf_sizes<32>::sym_size;
4019 else if (parameters->target().get_size() == 64)
4021 symsize = elfcpp::Elf_sizes<64>::sym_size;
4027 // Compute file offsets relative to the start of the symtab section.
4030 // Save space for the dummy symbol at the start of the section. We
4031 // never bother to write this out--it will just be left as zero.
4033 unsigned int local_symbol_index = 1;
4035 // Add STT_SECTION symbols for each Output section which needs one.
4036 for (Section_list::iterator p = this->section_list_.begin();
4037 p != this->section_list_.end();
4040 if (!(*p)->needs_symtab_index())
4041 (*p)->set_symtab_index(-1U);
4044 (*p)->set_symtab_index(local_symbol_index);
4045 ++local_symbol_index;
4050 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
4051 p != input_objects->relobj_end();
4054 unsigned int index = (*p)->finalize_local_symbols(local_symbol_index,
4056 off += (index - local_symbol_index) * symsize;
4057 local_symbol_index = index;
4060 unsigned int local_symcount = local_symbol_index;
4061 gold_assert(static_cast<off_t>(local_symcount * symsize) == off);
4065 if (this->dynsym_section_ == NULL)
4072 off_t locsize = local_dynamic_count * this->dynsym_section_->entsize();
4073 dynoff = this->dynsym_section_->offset() + locsize;
4074 dyncount = (this->dynsym_section_->data_size() - locsize) / symsize;
4075 gold_assert(static_cast<off_t>(dyncount * symsize)
4076 == this->dynsym_section_->data_size() - locsize);
4079 off_t global_off = off;
4080 off = symtab->finalize(off, dynoff, local_dynamic_count, dyncount,
4081 &this->sympool_, &local_symcount);
4083 if (!parameters->options().strip_all())
4085 this->sympool_.set_string_offsets();
4087 const char* symtab_name = this->namepool_.add(".symtab", false, NULL);
4088 Output_section* osymtab = this->make_output_section(symtab_name,
4092 this->symtab_section_ = osymtab;
4094 Output_section_data* pos = new Output_data_fixed_space(off, align,
4096 osymtab->add_output_section_data(pos);
4098 // We generate a .symtab_shndx section if we have more than
4099 // SHN_LORESERVE sections. Technically it is possible that we
4100 // don't need one, because it is possible that there are no
4101 // symbols in any of sections with indexes larger than
4102 // SHN_LORESERVE. That is probably unusual, though, and it is
4103 // easier to always create one than to compute section indexes
4104 // twice (once here, once when writing out the symbols).
4105 if (shnum >= elfcpp::SHN_LORESERVE)
4107 const char* symtab_xindex_name = this->namepool_.add(".symtab_shndx",
4109 Output_section* osymtab_xindex =
4110 this->make_output_section(symtab_xindex_name,
4111 elfcpp::SHT_SYMTAB_SHNDX, 0,
4112 ORDER_INVALID, false);
4114 size_t symcount = off / symsize;
4115 this->symtab_xindex_ = new Output_symtab_xindex(symcount);
4117 osymtab_xindex->add_output_section_data(this->symtab_xindex_);
4119 osymtab_xindex->set_link_section(osymtab);
4120 osymtab_xindex->set_addralign(4);
4121 osymtab_xindex->set_entsize(4);
4123 osymtab_xindex->set_after_input_sections();
4125 // This tells the driver code to wait until the symbol table
4126 // has written out before writing out the postprocessing
4127 // sections, including the .symtab_shndx section.
4128 this->any_postprocessing_sections_ = true;
4131 const char* strtab_name = this->namepool_.add(".strtab", false, NULL);
4132 Output_section* ostrtab = this->make_output_section(strtab_name,
4137 Output_section_data* pstr = new Output_data_strtab(&this->sympool_);
4138 ostrtab->add_output_section_data(pstr);
4141 if (!parameters->incremental_update())
4142 symtab_off = align_address(*poff, align);
4145 symtab_off = this->allocate(off, align, *poff);
4147 gold_fallback(_("out of patch space for symbol table; "
4148 "relink with --incremental-full"));
4149 gold_debug(DEBUG_INCREMENTAL,
4150 "create_symtab_sections: %08lx %08lx .symtab",
4151 static_cast<long>(symtab_off),
4152 static_cast<long>(off));
4155 symtab->set_file_offset(symtab_off + global_off);
4156 osymtab->set_file_offset(symtab_off);
4157 osymtab->finalize_data_size();
4158 osymtab->set_link_section(ostrtab);
4159 osymtab->set_info(local_symcount);
4160 osymtab->set_entsize(symsize);
4162 if (symtab_off + off > *poff)
4163 *poff = symtab_off + off;
4167 // Create the .shstrtab section, which holds the names of the
4168 // sections. At the time this is called, we have created all the
4169 // output sections except .shstrtab itself.
4172 Layout::create_shstrtab()
4174 // FIXME: We don't need to create a .shstrtab section if we are
4175 // stripping everything.
4177 const char* name = this->namepool_.add(".shstrtab", false, NULL);
4179 Output_section* os = this->make_output_section(name, elfcpp::SHT_STRTAB, 0,
4180 ORDER_INVALID, false);
4182 if (strcmp(parameters->options().compress_debug_sections(), "none") != 0)
4184 // We can't write out this section until we've set all the
4185 // section names, and we don't set the names of compressed
4186 // output sections until relocations are complete. FIXME: With
4187 // the current names we use, this is unnecessary.
4188 os->set_after_input_sections();
4191 Output_section_data* posd = new Output_data_strtab(&this->namepool_);
4192 os->add_output_section_data(posd);
4197 // Create the section headers. SIZE is 32 or 64. OFF is the file
4201 Layout::create_shdrs(const Output_section* shstrtab_section, off_t* poff)
4203 Output_section_headers* oshdrs;
4204 oshdrs = new Output_section_headers(this,
4205 &this->segment_list_,
4206 &this->section_list_,
4207 &this->unattached_section_list_,
4211 if (!parameters->incremental_update())
4212 off = align_address(*poff, oshdrs->addralign());
4215 oshdrs->pre_finalize_data_size();
4216 off = this->allocate(oshdrs->data_size(), oshdrs->addralign(), *poff);
4218 gold_fallback(_("out of patch space for section header table; "
4219 "relink with --incremental-full"));
4220 gold_debug(DEBUG_INCREMENTAL,
4221 "create_shdrs: %08lx %08lx (section header table)",
4222 static_cast<long>(off),
4223 static_cast<long>(off + oshdrs->data_size()));
4225 oshdrs->set_address_and_file_offset(0, off);
4226 off += oshdrs->data_size();
4229 this->section_headers_ = oshdrs;
4232 // Count the allocated sections.
4235 Layout::allocated_output_section_count() const
4237 size_t section_count = 0;
4238 for (Segment_list::const_iterator p = this->segment_list_.begin();
4239 p != this->segment_list_.end();
4241 section_count += (*p)->output_section_count();
4242 return section_count;
4245 // Create the dynamic symbol table.
4246 // *PLOCAL_DYNAMIC_COUNT will be set to the number of local symbols
4247 // from input objects, and *PFORCED_LOCAL_DYNAMIC_COUNT will be set
4248 // to the number of global symbols that have been forced local.
4249 // We need to remember the former because the forced-local symbols are
4250 // written along with the global symbols in Symtab::write_globals().
4253 Layout::create_dynamic_symtab(const Input_objects* input_objects,
4254 Symbol_table* symtab,
4255 Output_section** pdynstr,
4256 unsigned int* plocal_dynamic_count,
4257 unsigned int* pforced_local_dynamic_count,
4258 std::vector<Symbol*>* pdynamic_symbols,
4259 Versions* pversions)
4261 // Count all the symbols in the dynamic symbol table, and set the
4262 // dynamic symbol indexes.
4264 // Skip symbol 0, which is always all zeroes.
4265 unsigned int index = 1;
4267 // Add STT_SECTION symbols for each Output section which needs one.
4268 for (Section_list::iterator p = this->section_list_.begin();
4269 p != this->section_list_.end();
4272 if (!(*p)->needs_dynsym_index())
4273 (*p)->set_dynsym_index(-1U);
4276 (*p)->set_dynsym_index(index);
4281 // Count the local symbols that need to go in the dynamic symbol table,
4282 // and set the dynamic symbol indexes.
4283 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
4284 p != input_objects->relobj_end();
4287 unsigned int new_index = (*p)->set_local_dynsym_indexes(index);
4291 unsigned int local_symcount = index;
4292 unsigned int forced_local_count = 0;
4294 index = symtab->set_dynsym_indexes(index, &forced_local_count,
4295 pdynamic_symbols, &this->dynpool_,
4298 *plocal_dynamic_count = local_symcount;
4299 *pforced_local_dynamic_count = forced_local_count;
4303 const int size = parameters->target().get_size();
4306 symsize = elfcpp::Elf_sizes<32>::sym_size;
4309 else if (size == 64)
4311 symsize = elfcpp::Elf_sizes<64>::sym_size;
4317 // Create the dynamic symbol table section.
4319 Output_section* dynsym = this->choose_output_section(NULL, ".dynsym",
4323 ORDER_DYNAMIC_LINKER,
4324 false, false, false);
4326 // Check for NULL as a linker script may discard .dynsym.
4329 Output_section_data* odata = new Output_data_fixed_space(index * symsize,
4332 dynsym->add_output_section_data(odata);
4334 dynsym->set_info(local_symcount + forced_local_count);
4335 dynsym->set_entsize(symsize);
4336 dynsym->set_addralign(align);
4338 this->dynsym_section_ = dynsym;
4341 Output_data_dynamic* const odyn = this->dynamic_data_;
4344 odyn->add_section_address(elfcpp::DT_SYMTAB, dynsym);
4345 odyn->add_constant(elfcpp::DT_SYMENT, symsize);
4348 // If there are more than SHN_LORESERVE allocated sections, we
4349 // create a .dynsym_shndx section. It is possible that we don't
4350 // need one, because it is possible that there are no dynamic
4351 // symbols in any of the sections with indexes larger than
4352 // SHN_LORESERVE. This is probably unusual, though, and at this
4353 // time we don't know the actual section indexes so it is
4354 // inconvenient to check.
4355 if (this->allocated_output_section_count() >= elfcpp::SHN_LORESERVE)
4357 Output_section* dynsym_xindex =
4358 this->choose_output_section(NULL, ".dynsym_shndx",
4359 elfcpp::SHT_SYMTAB_SHNDX,
4361 false, ORDER_DYNAMIC_LINKER, false, false,
4364 if (dynsym_xindex != NULL)
4366 this->dynsym_xindex_ = new Output_symtab_xindex(index);
4368 dynsym_xindex->add_output_section_data(this->dynsym_xindex_);
4370 dynsym_xindex->set_link_section(dynsym);
4371 dynsym_xindex->set_addralign(4);
4372 dynsym_xindex->set_entsize(4);
4374 dynsym_xindex->set_after_input_sections();
4376 // This tells the driver code to wait until the symbol table
4377 // has written out before writing out the postprocessing
4378 // sections, including the .dynsym_shndx section.
4379 this->any_postprocessing_sections_ = true;
4383 // Create the dynamic string table section.
4385 Output_section* dynstr = this->choose_output_section(NULL, ".dynstr",
4389 ORDER_DYNAMIC_LINKER,
4390 false, false, false);
4394 Output_section_data* strdata = new Output_data_strtab(&this->dynpool_);
4395 dynstr->add_output_section_data(strdata);
4398 dynsym->set_link_section(dynstr);
4399 if (this->dynamic_section_ != NULL)
4400 this->dynamic_section_->set_link_section(dynstr);
4404 odyn->add_section_address(elfcpp::DT_STRTAB, dynstr);
4405 odyn->add_section_size(elfcpp::DT_STRSZ, dynstr);
4409 // Create the hash tables. The Gnu-style hash table must be
4410 // built first, because it changes the order of the symbols
4411 // in the dynamic symbol table.
4413 if (strcmp(parameters->options().hash_style(), "gnu") == 0
4414 || strcmp(parameters->options().hash_style(), "both") == 0)
4416 unsigned char* phash;
4417 unsigned int hashlen;
4418 Dynobj::create_gnu_hash_table(*pdynamic_symbols,
4419 local_symcount + forced_local_count,
4422 Output_section* hashsec =
4423 this->choose_output_section(NULL, ".gnu.hash", elfcpp::SHT_GNU_HASH,
4424 elfcpp::SHF_ALLOC, false,
4425 ORDER_DYNAMIC_LINKER, false, false,
4428 Output_section_data* hashdata = new Output_data_const_buffer(phash,
4432 if (hashsec != NULL && hashdata != NULL)
4433 hashsec->add_output_section_data(hashdata);
4435 if (hashsec != NULL)
4438 hashsec->set_link_section(dynsym);
4440 // For a 64-bit target, the entries in .gnu.hash do not have
4441 // a uniform size, so we only set the entry size for a
4443 if (parameters->target().get_size() == 32)
4444 hashsec->set_entsize(4);
4447 odyn->add_section_address(elfcpp::DT_GNU_HASH, hashsec);
4451 if (strcmp(parameters->options().hash_style(), "sysv") == 0
4452 || strcmp(parameters->options().hash_style(), "both") == 0)
4454 unsigned char* phash;
4455 unsigned int hashlen;
4456 Dynobj::create_elf_hash_table(*pdynamic_symbols,
4457 local_symcount + forced_local_count,
4460 Output_section* hashsec =
4461 this->choose_output_section(NULL, ".hash", elfcpp::SHT_HASH,
4462 elfcpp::SHF_ALLOC, false,
4463 ORDER_DYNAMIC_LINKER, false, false,
4466 Output_section_data* hashdata = new Output_data_const_buffer(phash,
4470 if (hashsec != NULL && hashdata != NULL)
4471 hashsec->add_output_section_data(hashdata);
4473 if (hashsec != NULL)
4476 hashsec->set_link_section(dynsym);
4477 hashsec->set_entsize(parameters->target().hash_entry_size() / 8);
4481 odyn->add_section_address(elfcpp::DT_HASH, hashsec);
4485 // Assign offsets to each local portion of the dynamic symbol table.
4488 Layout::assign_local_dynsym_offsets(const Input_objects* input_objects)
4490 Output_section* dynsym = this->dynsym_section_;
4494 off_t off = dynsym->offset();
4496 // Skip the dummy symbol at the start of the section.
4497 off += dynsym->entsize();
4499 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
4500 p != input_objects->relobj_end();
4503 unsigned int count = (*p)->set_local_dynsym_offset(off);
4504 off += count * dynsym->entsize();
4508 // Create the version sections.
4511 Layout::create_version_sections(const Versions* versions,
4512 const Symbol_table* symtab,
4513 unsigned int local_symcount,
4514 const std::vector<Symbol*>& dynamic_symbols,
4515 const Output_section* dynstr)
4517 if (!versions->any_defs() && !versions->any_needs())
4520 switch (parameters->size_and_endianness())
4522 #ifdef HAVE_TARGET_32_LITTLE
4523 case Parameters::TARGET_32_LITTLE:
4524 this->sized_create_version_sections<32, false>(versions, symtab,
4526 dynamic_symbols, dynstr);
4529 #ifdef HAVE_TARGET_32_BIG
4530 case Parameters::TARGET_32_BIG:
4531 this->sized_create_version_sections<32, true>(versions, symtab,
4533 dynamic_symbols, dynstr);
4536 #ifdef HAVE_TARGET_64_LITTLE
4537 case Parameters::TARGET_64_LITTLE:
4538 this->sized_create_version_sections<64, false>(versions, symtab,
4540 dynamic_symbols, dynstr);
4543 #ifdef HAVE_TARGET_64_BIG
4544 case Parameters::TARGET_64_BIG:
4545 this->sized_create_version_sections<64, true>(versions, symtab,
4547 dynamic_symbols, dynstr);
4555 // Create the version sections, sized version.
4557 template<int size, bool big_endian>
4559 Layout::sized_create_version_sections(
4560 const Versions* versions,
4561 const Symbol_table* symtab,
4562 unsigned int local_symcount,
4563 const std::vector<Symbol*>& dynamic_symbols,
4564 const Output_section* dynstr)
4566 Output_section* vsec = this->choose_output_section(NULL, ".gnu.version",
4567 elfcpp::SHT_GNU_versym,
4570 ORDER_DYNAMIC_LINKER,
4571 false, false, false);
4573 // Check for NULL since a linker script may discard this section.
4576 unsigned char* vbuf;
4578 versions->symbol_section_contents<size, big_endian>(symtab,
4584 Output_section_data* vdata = new Output_data_const_buffer(vbuf, vsize, 2,
4587 vsec->add_output_section_data(vdata);
4588 vsec->set_entsize(2);
4589 vsec->set_link_section(this->dynsym_section_);
4592 Output_data_dynamic* const odyn = this->dynamic_data_;
4593 if (odyn != NULL && vsec != NULL)
4594 odyn->add_section_address(elfcpp::DT_VERSYM, vsec);
4596 if (versions->any_defs())
4598 Output_section* vdsec;
4599 vdsec = this->choose_output_section(NULL, ".gnu.version_d",
4600 elfcpp::SHT_GNU_verdef,
4602 false, ORDER_DYNAMIC_LINKER, false,
4607 unsigned char* vdbuf;
4608 unsigned int vdsize;
4609 unsigned int vdentries;
4610 versions->def_section_contents<size, big_endian>(&this->dynpool_,
4614 Output_section_data* vddata =
4615 new Output_data_const_buffer(vdbuf, vdsize, 4, "** version defs");
4617 vdsec->add_output_section_data(vddata);
4618 vdsec->set_link_section(dynstr);
4619 vdsec->set_info(vdentries);
4623 odyn->add_section_address(elfcpp::DT_VERDEF, vdsec);
4624 odyn->add_constant(elfcpp::DT_VERDEFNUM, vdentries);
4629 if (versions->any_needs())
4631 Output_section* vnsec;
4632 vnsec = this->choose_output_section(NULL, ".gnu.version_r",
4633 elfcpp::SHT_GNU_verneed,
4635 false, ORDER_DYNAMIC_LINKER, false,
4640 unsigned char* vnbuf;
4641 unsigned int vnsize;
4642 unsigned int vnentries;
4643 versions->need_section_contents<size, big_endian>(&this->dynpool_,
4647 Output_section_data* vndata =
4648 new Output_data_const_buffer(vnbuf, vnsize, 4, "** version refs");
4650 vnsec->add_output_section_data(vndata);
4651 vnsec->set_link_section(dynstr);
4652 vnsec->set_info(vnentries);
4656 odyn->add_section_address(elfcpp::DT_VERNEED, vnsec);
4657 odyn->add_constant(elfcpp::DT_VERNEEDNUM, vnentries);
4663 // Create the .interp section and PT_INTERP segment.
4666 Layout::create_interp(const Target* target)
4668 gold_assert(this->interp_segment_ == NULL);
4670 const char* interp = parameters->options().dynamic_linker();
4673 interp = target->dynamic_linker();
4674 gold_assert(interp != NULL);
4677 size_t len = strlen(interp) + 1;
4679 Output_section_data* odata = new Output_data_const(interp, len, 1);
4681 Output_section* osec = this->choose_output_section(NULL, ".interp",
4682 elfcpp::SHT_PROGBITS,
4684 false, ORDER_INTERP,
4685 false, false, false);
4687 osec->add_output_section_data(odata);
4690 // Add dynamic tags for the PLT and the dynamic relocs. This is
4691 // called by the target-specific code. This does nothing if not doing
4694 // USE_REL is true for REL relocs rather than RELA relocs.
4696 // If PLT_GOT is not NULL, then DT_PLTGOT points to it.
4698 // If PLT_REL is not NULL, it is used for DT_PLTRELSZ, and DT_JMPREL,
4699 // and we also set DT_PLTREL. We use PLT_REL's output section, since
4700 // some targets have multiple reloc sections in PLT_REL.
4702 // If DYN_REL is not NULL, it is used for DT_REL/DT_RELA,
4703 // DT_RELSZ/DT_RELASZ, DT_RELENT/DT_RELAENT. Again we use the output
4706 // If ADD_DEBUG is true, we add a DT_DEBUG entry when generating an
4710 Layout::add_target_dynamic_tags(bool use_rel, const Output_data* plt_got,
4711 const Output_data* plt_rel,
4712 const Output_data_reloc_generic* dyn_rel,
4713 bool add_debug, bool dynrel_includes_plt)
4715 Output_data_dynamic* odyn = this->dynamic_data_;
4719 if (plt_got != NULL && plt_got->output_section() != NULL)
4720 odyn->add_section_address(elfcpp::DT_PLTGOT, plt_got);
4722 if (plt_rel != NULL && plt_rel->output_section() != NULL)
4724 odyn->add_section_size(elfcpp::DT_PLTRELSZ, plt_rel->output_section());
4725 odyn->add_section_address(elfcpp::DT_JMPREL, plt_rel->output_section());
4726 odyn->add_constant(elfcpp::DT_PLTREL,
4727 use_rel ? elfcpp::DT_REL : elfcpp::DT_RELA);
4730 if ((dyn_rel != NULL && dyn_rel->output_section() != NULL)
4731 || (dynrel_includes_plt
4733 && plt_rel->output_section() != NULL))
4735 bool have_dyn_rel = dyn_rel != NULL && dyn_rel->output_section() != NULL;
4736 bool have_plt_rel = plt_rel != NULL && plt_rel->output_section() != NULL;
4737 odyn->add_section_address(use_rel ? elfcpp::DT_REL : elfcpp::DT_RELA,
4739 ? dyn_rel->output_section()
4740 : plt_rel->output_section()));
4741 elfcpp::DT size_tag = use_rel ? elfcpp::DT_RELSZ : elfcpp::DT_RELASZ;
4742 if (have_dyn_rel && have_plt_rel && dynrel_includes_plt)
4743 odyn->add_section_size(size_tag,
4744 dyn_rel->output_section(),
4745 plt_rel->output_section());
4746 else if (have_dyn_rel)
4747 odyn->add_section_size(size_tag, dyn_rel->output_section());
4749 odyn->add_section_size(size_tag, plt_rel->output_section());
4750 const int size = parameters->target().get_size();
4755 rel_tag = elfcpp::DT_RELENT;
4757 rel_size = Reloc_types<elfcpp::SHT_REL, 32, false>::reloc_size;
4758 else if (size == 64)
4759 rel_size = Reloc_types<elfcpp::SHT_REL, 64, false>::reloc_size;
4765 rel_tag = elfcpp::DT_RELAENT;
4767 rel_size = Reloc_types<elfcpp::SHT_RELA, 32, false>::reloc_size;
4768 else if (size == 64)
4769 rel_size = Reloc_types<elfcpp::SHT_RELA, 64, false>::reloc_size;
4773 odyn->add_constant(rel_tag, rel_size);
4775 if (parameters->options().combreloc() && have_dyn_rel)
4777 size_t c = dyn_rel->relative_reloc_count();
4779 odyn->add_constant((use_rel
4780 ? elfcpp::DT_RELCOUNT
4781 : elfcpp::DT_RELACOUNT),
4786 if (add_debug && !parameters->options().shared())
4788 // The value of the DT_DEBUG tag is filled in by the dynamic
4789 // linker at run time, and used by the debugger.
4790 odyn->add_constant(elfcpp::DT_DEBUG, 0);
4795 Layout::add_target_specific_dynamic_tag(elfcpp::DT tag, unsigned int val)
4797 Output_data_dynamic* odyn = this->dynamic_data_;
4800 odyn->add_constant(tag, val);
4803 // Finish the .dynamic section and PT_DYNAMIC segment.
4806 Layout::finish_dynamic_section(const Input_objects* input_objects,
4807 const Symbol_table* symtab)
4809 if (!this->script_options_->saw_phdrs_clause()
4810 && this->dynamic_section_ != NULL)
4812 Output_segment* oseg = this->make_output_segment(elfcpp::PT_DYNAMIC,
4815 oseg->add_output_section_to_nonload(this->dynamic_section_,
4816 elfcpp::PF_R | elfcpp::PF_W);
4819 Output_data_dynamic* const odyn = this->dynamic_data_;
4823 for (Input_objects::Dynobj_iterator p = input_objects->dynobj_begin();
4824 p != input_objects->dynobj_end();
4827 if (!(*p)->is_needed() && (*p)->as_needed())
4829 // This dynamic object was linked with --as-needed, but it
4834 odyn->add_string(elfcpp::DT_NEEDED, (*p)->soname());
4837 if (parameters->options().shared())
4839 const char* soname = parameters->options().soname();
4841 odyn->add_string(elfcpp::DT_SONAME, soname);
4844 Symbol* sym = symtab->lookup(parameters->options().init());
4845 if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj())
4846 odyn->add_symbol(elfcpp::DT_INIT, sym);
4848 sym = symtab->lookup(parameters->options().fini());
4849 if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj())
4850 odyn->add_symbol(elfcpp::DT_FINI, sym);
4852 // Look for .init_array, .preinit_array and .fini_array by checking
4854 for(Layout::Section_list::const_iterator p = this->section_list_.begin();
4855 p != this->section_list_.end();
4857 switch((*p)->type())
4859 case elfcpp::SHT_FINI_ARRAY:
4860 odyn->add_section_address(elfcpp::DT_FINI_ARRAY, *p);
4861 odyn->add_section_size(elfcpp::DT_FINI_ARRAYSZ, *p);
4863 case elfcpp::SHT_INIT_ARRAY:
4864 odyn->add_section_address(elfcpp::DT_INIT_ARRAY, *p);
4865 odyn->add_section_size(elfcpp::DT_INIT_ARRAYSZ, *p);
4867 case elfcpp::SHT_PREINIT_ARRAY:
4868 odyn->add_section_address(elfcpp::DT_PREINIT_ARRAY, *p);
4869 odyn->add_section_size(elfcpp::DT_PREINIT_ARRAYSZ, *p);
4875 // Add a DT_RPATH entry if needed.
4876 const General_options::Dir_list& rpath(parameters->options().rpath());
4879 std::string rpath_val;
4880 for (General_options::Dir_list::const_iterator p = rpath.begin();
4884 if (rpath_val.empty())
4885 rpath_val = p->name();
4888 // Eliminate duplicates.
4889 General_options::Dir_list::const_iterator q;
4890 for (q = rpath.begin(); q != p; ++q)
4891 if (q->name() == p->name())
4896 rpath_val += p->name();
4901 if (!parameters->options().enable_new_dtags())
4902 odyn->add_string(elfcpp::DT_RPATH, rpath_val);
4904 odyn->add_string(elfcpp::DT_RUNPATH, rpath_val);
4907 // Look for text segments that have dynamic relocations.
4908 bool have_textrel = false;
4909 if (!this->script_options_->saw_sections_clause())
4911 for (Segment_list::const_iterator p = this->segment_list_.begin();
4912 p != this->segment_list_.end();
4915 if ((*p)->type() == elfcpp::PT_LOAD
4916 && ((*p)->flags() & elfcpp::PF_W) == 0
4917 && (*p)->has_dynamic_reloc())
4919 have_textrel = true;
4926 // We don't know the section -> segment mapping, so we are
4927 // conservative and just look for readonly sections with
4928 // relocations. If those sections wind up in writable segments,
4929 // then we have created an unnecessary DT_TEXTREL entry.
4930 for (Section_list::const_iterator p = this->section_list_.begin();
4931 p != this->section_list_.end();
4934 if (((*p)->flags() & elfcpp::SHF_ALLOC) != 0
4935 && ((*p)->flags() & elfcpp::SHF_WRITE) == 0
4936 && (*p)->has_dynamic_reloc())
4938 have_textrel = true;
4944 if (parameters->options().filter() != NULL)
4945 odyn->add_string(elfcpp::DT_FILTER, parameters->options().filter());
4946 if (parameters->options().any_auxiliary())
4948 for (options::String_set::const_iterator p =
4949 parameters->options().auxiliary_begin();
4950 p != parameters->options().auxiliary_end();
4952 odyn->add_string(elfcpp::DT_AUXILIARY, *p);
4955 // Add a DT_FLAGS entry if necessary.
4956 unsigned int flags = 0;
4959 // Add a DT_TEXTREL for compatibility with older loaders.
4960 odyn->add_constant(elfcpp::DT_TEXTREL, 0);
4961 flags |= elfcpp::DF_TEXTREL;
4963 if (parameters->options().text())
4964 gold_error(_("read-only segment has dynamic relocations"));
4965 else if (parameters->options().warn_shared_textrel()
4966 && parameters->options().shared())
4967 gold_warning(_("shared library text segment is not shareable"));
4969 if (parameters->options().shared() && this->has_static_tls())
4970 flags |= elfcpp::DF_STATIC_TLS;
4971 if (parameters->options().origin())
4972 flags |= elfcpp::DF_ORIGIN;
4973 if (parameters->options().Bsymbolic()
4974 && !parameters->options().have_dynamic_list())
4976 flags |= elfcpp::DF_SYMBOLIC;
4977 // Add DT_SYMBOLIC for compatibility with older loaders.
4978 odyn->add_constant(elfcpp::DT_SYMBOLIC, 0);
4980 if (parameters->options().now())
4981 flags |= elfcpp::DF_BIND_NOW;
4983 odyn->add_constant(elfcpp::DT_FLAGS, flags);
4986 if (parameters->options().global())
4987 flags |= elfcpp::DF_1_GLOBAL;
4988 if (parameters->options().initfirst())
4989 flags |= elfcpp::DF_1_INITFIRST;
4990 if (parameters->options().interpose())
4991 flags |= elfcpp::DF_1_INTERPOSE;
4992 if (parameters->options().loadfltr())
4993 flags |= elfcpp::DF_1_LOADFLTR;
4994 if (parameters->options().nodefaultlib())
4995 flags |= elfcpp::DF_1_NODEFLIB;
4996 if (parameters->options().nodelete())
4997 flags |= elfcpp::DF_1_NODELETE;
4998 if (parameters->options().nodlopen())
4999 flags |= elfcpp::DF_1_NOOPEN;
5000 if (parameters->options().nodump())
5001 flags |= elfcpp::DF_1_NODUMP;
5002 if (!parameters->options().shared())
5003 flags &= ~(elfcpp::DF_1_INITFIRST
5004 | elfcpp::DF_1_NODELETE
5005 | elfcpp::DF_1_NOOPEN);
5006 if (parameters->options().origin())
5007 flags |= elfcpp::DF_1_ORIGIN;
5008 if (parameters->options().now())
5009 flags |= elfcpp::DF_1_NOW;
5010 if (parameters->options().Bgroup())
5011 flags |= elfcpp::DF_1_GROUP;
5013 odyn->add_constant(elfcpp::DT_FLAGS_1, flags);
5016 // Set the size of the _DYNAMIC symbol table to be the size of the
5020 Layout::set_dynamic_symbol_size(const Symbol_table* symtab)
5022 Output_data_dynamic* const odyn = this->dynamic_data_;
5025 odyn->finalize_data_size();
5026 if (this->dynamic_symbol_ == NULL)
5028 off_t data_size = odyn->data_size();
5029 const int size = parameters->target().get_size();
5031 symtab->get_sized_symbol<32>(this->dynamic_symbol_)->set_symsize(data_size);
5032 else if (size == 64)
5033 symtab->get_sized_symbol<64>(this->dynamic_symbol_)->set_symsize(data_size);
5038 // The mapping of input section name prefixes to output section names.
5039 // In some cases one prefix is itself a prefix of another prefix; in
5040 // such a case the longer prefix must come first. These prefixes are
5041 // based on the GNU linker default ELF linker script.
5043 #define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 }
5044 #define MAPPING_INIT_EXACT(f, t) { f, 0, t, sizeof(t) - 1 }
5045 const Layout::Section_name_mapping Layout::section_name_mapping[] =
5047 MAPPING_INIT(".text.", ".text"),
5048 MAPPING_INIT(".rodata.", ".rodata"),
5049 MAPPING_INIT(".data.rel.ro.local.", ".data.rel.ro.local"),
5050 MAPPING_INIT_EXACT(".data.rel.ro.local", ".data.rel.ro.local"),
5051 MAPPING_INIT(".data.rel.ro.", ".data.rel.ro"),
5052 MAPPING_INIT_EXACT(".data.rel.ro", ".data.rel.ro"),
5053 MAPPING_INIT(".data.", ".data"),
5054 MAPPING_INIT(".bss.", ".bss"),
5055 MAPPING_INIT(".tdata.", ".tdata"),
5056 MAPPING_INIT(".tbss.", ".tbss"),
5057 MAPPING_INIT(".init_array.", ".init_array"),
5058 MAPPING_INIT(".fini_array.", ".fini_array"),
5059 MAPPING_INIT(".sdata.", ".sdata"),
5060 MAPPING_INIT(".sbss.", ".sbss"),
5061 // FIXME: In the GNU linker, .sbss2 and .sdata2 are handled
5062 // differently depending on whether it is creating a shared library.
5063 MAPPING_INIT(".sdata2.", ".sdata"),
5064 MAPPING_INIT(".sbss2.", ".sbss"),
5065 MAPPING_INIT(".lrodata.", ".lrodata"),
5066 MAPPING_INIT(".ldata.", ".ldata"),
5067 MAPPING_INIT(".lbss.", ".lbss"),
5068 MAPPING_INIT(".gcc_except_table.", ".gcc_except_table"),
5069 MAPPING_INIT(".gnu.linkonce.d.rel.ro.local.", ".data.rel.ro.local"),
5070 MAPPING_INIT(".gnu.linkonce.d.rel.ro.", ".data.rel.ro"),
5071 MAPPING_INIT(".gnu.linkonce.t.", ".text"),
5072 MAPPING_INIT(".gnu.linkonce.r.", ".rodata"),
5073 MAPPING_INIT(".gnu.linkonce.d.", ".data"),
5074 MAPPING_INIT(".gnu.linkonce.b.", ".bss"),
5075 MAPPING_INIT(".gnu.linkonce.s.", ".sdata"),
5076 MAPPING_INIT(".gnu.linkonce.sb.", ".sbss"),
5077 MAPPING_INIT(".gnu.linkonce.s2.", ".sdata"),
5078 MAPPING_INIT(".gnu.linkonce.sb2.", ".sbss"),
5079 MAPPING_INIT(".gnu.linkonce.wi.", ".debug_info"),
5080 MAPPING_INIT(".gnu.linkonce.td.", ".tdata"),
5081 MAPPING_INIT(".gnu.linkonce.tb.", ".tbss"),
5082 MAPPING_INIT(".gnu.linkonce.lr.", ".lrodata"),
5083 MAPPING_INIT(".gnu.linkonce.l.", ".ldata"),
5084 MAPPING_INIT(".gnu.linkonce.lb.", ".lbss"),
5085 MAPPING_INIT(".ARM.extab", ".ARM.extab"),
5086 MAPPING_INIT(".gnu.linkonce.armextab.", ".ARM.extab"),
5087 MAPPING_INIT(".ARM.exidx", ".ARM.exidx"),
5088 MAPPING_INIT(".gnu.linkonce.armexidx.", ".ARM.exidx"),
5091 #undef MAPPING_INIT_EXACT
5093 const int Layout::section_name_mapping_count =
5094 (sizeof(Layout::section_name_mapping)
5095 / sizeof(Layout::section_name_mapping[0]));
5097 // Choose the output section name to use given an input section name.
5098 // Set *PLEN to the length of the name. *PLEN is initialized to the
5102 Layout::output_section_name(const Relobj* relobj, const char* name,
5105 // gcc 4.3 generates the following sorts of section names when it
5106 // needs a section name specific to a function:
5112 // .data.rel.local.FN
5114 // .data.rel.ro.local.FN
5121 // The GNU linker maps all of those to the part before the .FN,
5122 // except that .data.rel.local.FN is mapped to .data, and
5123 // .data.rel.ro.local.FN is mapped to .data.rel.ro. The sections
5124 // beginning with .data.rel.ro.local are grouped together.
5126 // For an anonymous namespace, the string FN can contain a '.'.
5128 // Also of interest: .rodata.strN.N, .rodata.cstN, both of which the
5129 // GNU linker maps to .rodata.
5131 // The .data.rel.ro sections are used with -z relro. The sections
5132 // are recognized by name. We use the same names that the GNU
5133 // linker does for these sections.
5135 // It is hard to handle this in a principled way, so we don't even
5136 // try. We use a table of mappings. If the input section name is
5137 // not found in the table, we simply use it as the output section
5140 const Section_name_mapping* psnm = section_name_mapping;
5141 for (int i = 0; i < section_name_mapping_count; ++i, ++psnm)
5143 if (psnm->fromlen > 0)
5145 if (strncmp(name, psnm->from, psnm->fromlen) == 0)
5147 *plen = psnm->tolen;
5153 if (strcmp(name, psnm->from) == 0)
5155 *plen = psnm->tolen;
5161 // As an additional complication, .ctors sections are output in
5162 // either .ctors or .init_array sections, and .dtors sections are
5163 // output in either .dtors or .fini_array sections.
5164 if (is_prefix_of(".ctors.", name) || is_prefix_of(".dtors.", name))
5166 if (parameters->options().ctors_in_init_array())
5169 return name[1] == 'c' ? ".init_array" : ".fini_array";
5174 return name[1] == 'c' ? ".ctors" : ".dtors";
5177 if (parameters->options().ctors_in_init_array()
5178 && (strcmp(name, ".ctors") == 0 || strcmp(name, ".dtors") == 0))
5180 // To make .init_array/.fini_array work with gcc we must exclude
5181 // .ctors and .dtors sections from the crtbegin and crtend
5184 || (!Layout::match_file_name(relobj, "crtbegin")
5185 && !Layout::match_file_name(relobj, "crtend")))
5188 return name[1] == 'c' ? ".init_array" : ".fini_array";
5195 // Return true if RELOBJ is an input file whose base name matches
5196 // FILE_NAME. The base name must have an extension of ".o", and must
5197 // be exactly FILE_NAME.o or FILE_NAME, one character, ".o". This is
5198 // to match crtbegin.o as well as crtbeginS.o without getting confused
5199 // by other possibilities. Overall matching the file name this way is
5200 // a dreadful hack, but the GNU linker does it in order to better
5201 // support gcc, and we need to be compatible.
5204 Layout::match_file_name(const Relobj* relobj, const char* match)
5206 const std::string& file_name(relobj->name());
5207 const char* base_name = lbasename(file_name.c_str());
5208 size_t match_len = strlen(match);
5209 if (strncmp(base_name, match, match_len) != 0)
5211 size_t base_len = strlen(base_name);
5212 if (base_len != match_len + 2 && base_len != match_len + 3)
5214 return memcmp(base_name + base_len - 2, ".o", 2) == 0;
5217 // Check if a comdat group or .gnu.linkonce section with the given
5218 // NAME is selected for the link. If there is already a section,
5219 // *KEPT_SECTION is set to point to the existing section and the
5220 // function returns false. Otherwise, OBJECT, SHNDX, IS_COMDAT, and
5221 // IS_GROUP_NAME are recorded for this NAME in the layout object,
5222 // *KEPT_SECTION is set to the internal copy and the function returns
5226 Layout::find_or_add_kept_section(const std::string& name,
5231 Kept_section** kept_section)
5233 // It's normal to see a couple of entries here, for the x86 thunk
5234 // sections. If we see more than a few, we're linking a C++
5235 // program, and we resize to get more space to minimize rehashing.
5236 if (this->signatures_.size() > 4
5237 && !this->resized_signatures_)
5239 reserve_unordered_map(&this->signatures_,
5240 this->number_of_input_files_ * 64);
5241 this->resized_signatures_ = true;
5244 Kept_section candidate;
5245 std::pair<Signatures::iterator, bool> ins =
5246 this->signatures_.insert(std::make_pair(name, candidate));
5248 if (kept_section != NULL)
5249 *kept_section = &ins.first->second;
5252 // This is the first time we've seen this signature.
5253 ins.first->second.set_object(object);
5254 ins.first->second.set_shndx(shndx);
5256 ins.first->second.set_is_comdat();
5258 ins.first->second.set_is_group_name();
5262 // We have already seen this signature.
5264 if (ins.first->second.is_group_name())
5266 // We've already seen a real section group with this signature.
5267 // If the kept group is from a plugin object, and we're in the
5268 // replacement phase, accept the new one as a replacement.
5269 if (ins.first->second.object() == NULL
5270 && parameters->options().plugins()->in_replacement_phase())
5272 ins.first->second.set_object(object);
5273 ins.first->second.set_shndx(shndx);
5278 else if (is_group_name)
5280 // This is a real section group, and we've already seen a
5281 // linkonce section with this signature. Record that we've seen
5282 // a section group, and don't include this section group.
5283 ins.first->second.set_is_group_name();
5288 // We've already seen a linkonce section and this is a linkonce
5289 // section. These don't block each other--this may be the same
5290 // symbol name with different section types.
5295 // Store the allocated sections into the section list.
5298 Layout::get_allocated_sections(Section_list* section_list) const
5300 for (Section_list::const_iterator p = this->section_list_.begin();
5301 p != this->section_list_.end();
5303 if (((*p)->flags() & elfcpp::SHF_ALLOC) != 0)
5304 section_list->push_back(*p);
5307 // Store the executable sections into the section list.
5310 Layout::get_executable_sections(Section_list* section_list) const
5312 for (Section_list::const_iterator p = this->section_list_.begin();
5313 p != this->section_list_.end();
5315 if (((*p)->flags() & (elfcpp::SHF_ALLOC | elfcpp::SHF_EXECINSTR))
5316 == (elfcpp::SHF_ALLOC | elfcpp::SHF_EXECINSTR))
5317 section_list->push_back(*p);
5320 // Create an output segment.
5323 Layout::make_output_segment(elfcpp::Elf_Word type, elfcpp::Elf_Word flags)
5325 gold_assert(!parameters->options().relocatable());
5326 Output_segment* oseg = new Output_segment(type, flags);
5327 this->segment_list_.push_back(oseg);
5329 if (type == elfcpp::PT_TLS)
5330 this->tls_segment_ = oseg;
5331 else if (type == elfcpp::PT_GNU_RELRO)
5332 this->relro_segment_ = oseg;
5333 else if (type == elfcpp::PT_INTERP)
5334 this->interp_segment_ = oseg;
5339 // Return the file offset of the normal symbol table.
5342 Layout::symtab_section_offset() const
5344 if (this->symtab_section_ != NULL)
5345 return this->symtab_section_->offset();
5349 // Return the section index of the normal symbol table. It may have
5350 // been stripped by the -s/--strip-all option.
5353 Layout::symtab_section_shndx() const
5355 if (this->symtab_section_ != NULL)
5356 return this->symtab_section_->out_shndx();
5360 // Write out the Output_sections. Most won't have anything to write,
5361 // since most of the data will come from input sections which are
5362 // handled elsewhere. But some Output_sections do have Output_data.
5365 Layout::write_output_sections(Output_file* of) const
5367 for (Section_list::const_iterator p = this->section_list_.begin();
5368 p != this->section_list_.end();
5371 if (!(*p)->after_input_sections())
5376 // Write out data not associated with a section or the symbol table.
5379 Layout::write_data(const Symbol_table* symtab, Output_file* of) const
5381 if (!parameters->options().strip_all())
5383 const Output_section* symtab_section = this->symtab_section_;
5384 for (Section_list::const_iterator p = this->section_list_.begin();
5385 p != this->section_list_.end();
5388 if ((*p)->needs_symtab_index())
5390 gold_assert(symtab_section != NULL);
5391 unsigned int index = (*p)->symtab_index();
5392 gold_assert(index > 0 && index != -1U);
5393 off_t off = (symtab_section->offset()
5394 + index * symtab_section->entsize());
5395 symtab->write_section_symbol(*p, this->symtab_xindex_, of, off);
5400 const Output_section* dynsym_section = this->dynsym_section_;
5401 for (Section_list::const_iterator p = this->section_list_.begin();
5402 p != this->section_list_.end();
5405 if ((*p)->needs_dynsym_index())
5407 gold_assert(dynsym_section != NULL);
5408 unsigned int index = (*p)->dynsym_index();
5409 gold_assert(index > 0 && index != -1U);
5410 off_t off = (dynsym_section->offset()
5411 + index * dynsym_section->entsize());
5412 symtab->write_section_symbol(*p, this->dynsym_xindex_, of, off);
5416 // Write out the Output_data which are not in an Output_section.
5417 for (Data_list::const_iterator p = this->special_output_list_.begin();
5418 p != this->special_output_list_.end();
5422 // Write out the Output_data which are not in an Output_section
5423 // and are regenerated in each iteration of relaxation.
5424 for (Data_list::const_iterator p = this->relax_output_list_.begin();
5425 p != this->relax_output_list_.end();
5430 // Write out the Output_sections which can only be written after the
5431 // input sections are complete.
5434 Layout::write_sections_after_input_sections(Output_file* of)
5436 // Determine the final section offsets, and thus the final output
5437 // file size. Note we finalize the .shstrab last, to allow the
5438 // after_input_section sections to modify their section-names before
5440 if (this->any_postprocessing_sections_)
5442 off_t off = this->output_file_size_;
5443 off = this->set_section_offsets(off, POSTPROCESSING_SECTIONS_PASS);
5445 // Now that we've finalized the names, we can finalize the shstrab.
5447 this->set_section_offsets(off,
5448 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS);
5450 if (off > this->output_file_size_)
5453 this->output_file_size_ = off;
5457 for (Section_list::const_iterator p = this->section_list_.begin();
5458 p != this->section_list_.end();
5461 if ((*p)->after_input_sections())
5465 this->section_headers_->write(of);
5468 // If a tree-style build ID was requested, the parallel part of that computation
5469 // is already done, and the final hash-of-hashes is computed here. For other
5470 // types of build IDs, all the work is done here.
5473 Layout::write_build_id(Output_file* of, unsigned char* array_of_hashes,
5474 size_t size_of_hashes) const
5476 if (this->build_id_note_ == NULL)
5479 unsigned char* ov = of->get_output_view(this->build_id_note_->offset(),
5480 this->build_id_note_->data_size());
5482 if (array_of_hashes == NULL)
5484 const size_t output_file_size = this->output_file_size();
5485 const unsigned char* iv = of->get_input_view(0, output_file_size);
5486 const char* style = parameters->options().build_id();
5488 // If we get here with style == "tree" then the output must be
5489 // too small for chunking, and we use SHA-1 in that case.
5490 if ((strcmp(style, "sha1") == 0) || (strcmp(style, "tree") == 0))
5491 sha1_buffer(reinterpret_cast<const char*>(iv), output_file_size, ov);
5492 else if (strcmp(style, "md5") == 0)
5493 md5_buffer(reinterpret_cast<const char*>(iv), output_file_size, ov);
5497 of->free_input_view(0, output_file_size, iv);
5501 // Non-overlapping substrings of the output file have been hashed.
5502 // Compute SHA-1 hash of the hashes.
5503 sha1_buffer(reinterpret_cast<const char*>(array_of_hashes),
5504 size_of_hashes, ov);
5505 delete[] array_of_hashes;
5508 of->write_output_view(this->build_id_note_->offset(),
5509 this->build_id_note_->data_size(),
5513 // Write out a binary file. This is called after the link is
5514 // complete. IN is the temporary output file we used to generate the
5515 // ELF code. We simply walk through the segments, read them from
5516 // their file offset in IN, and write them to their load address in
5517 // the output file. FIXME: with a bit more work, we could support
5518 // S-records and/or Intel hex format here.
5521 Layout::write_binary(Output_file* in) const
5523 gold_assert(parameters->options().oformat_enum()
5524 == General_options::OBJECT_FORMAT_BINARY);
5526 // Get the size of the binary file.
5527 uint64_t max_load_address = 0;
5528 for (Segment_list::const_iterator p = this->segment_list_.begin();
5529 p != this->segment_list_.end();
5532 if ((*p)->type() == elfcpp::PT_LOAD && (*p)->filesz() > 0)
5534 uint64_t max_paddr = (*p)->paddr() + (*p)->filesz();
5535 if (max_paddr > max_load_address)
5536 max_load_address = max_paddr;
5540 Output_file out(parameters->options().output_file_name());
5541 out.open(max_load_address);
5543 for (Segment_list::const_iterator p = this->segment_list_.begin();
5544 p != this->segment_list_.end();
5547 if ((*p)->type() == elfcpp::PT_LOAD && (*p)->filesz() > 0)
5549 const unsigned char* vin = in->get_input_view((*p)->offset(),
5551 unsigned char* vout = out.get_output_view((*p)->paddr(),
5553 memcpy(vout, vin, (*p)->filesz());
5554 out.write_output_view((*p)->paddr(), (*p)->filesz(), vout);
5555 in->free_input_view((*p)->offset(), (*p)->filesz(), vin);
5562 // Print the output sections to the map file.
5565 Layout::print_to_mapfile(Mapfile* mapfile) const
5567 for (Segment_list::const_iterator p = this->segment_list_.begin();
5568 p != this->segment_list_.end();
5570 (*p)->print_sections_to_mapfile(mapfile);
5571 for (Section_list::const_iterator p = this->unattached_section_list_.begin();
5572 p != this->unattached_section_list_.end();
5574 (*p)->print_to_mapfile(mapfile);
5577 // Print statistical information to stderr. This is used for --stats.
5580 Layout::print_stats() const
5582 this->namepool_.print_stats("section name pool");
5583 this->sympool_.print_stats("output symbol name pool");
5584 this->dynpool_.print_stats("dynamic name pool");
5586 for (Section_list::const_iterator p = this->section_list_.begin();
5587 p != this->section_list_.end();
5589 (*p)->print_merge_stats();
5592 // Write_sections_task methods.
5594 // We can always run this task.
5597 Write_sections_task::is_runnable()
5602 // We need to unlock both OUTPUT_SECTIONS_BLOCKER and FINAL_BLOCKER
5606 Write_sections_task::locks(Task_locker* tl)
5608 tl->add(this, this->output_sections_blocker_);
5609 if (this->input_sections_blocker_ != NULL)
5610 tl->add(this, this->input_sections_blocker_);
5611 tl->add(this, this->final_blocker_);
5614 // Run the task--write out the data.
5617 Write_sections_task::run(Workqueue*)
5619 this->layout_->write_output_sections(this->of_);
5622 // Write_data_task methods.
5624 // We can always run this task.
5627 Write_data_task::is_runnable()
5632 // We need to unlock FINAL_BLOCKER when finished.
5635 Write_data_task::locks(Task_locker* tl)
5637 tl->add(this, this->final_blocker_);
5640 // Run the task--write out the data.
5643 Write_data_task::run(Workqueue*)
5645 this->layout_->write_data(this->symtab_, this->of_);
5648 // Write_symbols_task methods.
5650 // We can always run this task.
5653 Write_symbols_task::is_runnable()
5658 // We need to unlock FINAL_BLOCKER when finished.
5661 Write_symbols_task::locks(Task_locker* tl)
5663 tl->add(this, this->final_blocker_);
5666 // Run the task--write out the symbols.
5669 Write_symbols_task::run(Workqueue*)
5671 this->symtab_->write_globals(this->sympool_, this->dynpool_,
5672 this->layout_->symtab_xindex(),
5673 this->layout_->dynsym_xindex(), this->of_);
5676 // Write_after_input_sections_task methods.
5678 // We can only run this task after the input sections have completed.
5681 Write_after_input_sections_task::is_runnable()
5683 if (this->input_sections_blocker_->is_blocked())
5684 return this->input_sections_blocker_;
5688 // We need to unlock FINAL_BLOCKER when finished.
5691 Write_after_input_sections_task::locks(Task_locker* tl)
5693 tl->add(this, this->final_blocker_);
5699 Write_after_input_sections_task::run(Workqueue*)
5701 this->layout_->write_sections_after_input_sections(this->of_);
5704 // Build IDs can be computed as a "flat" sha1 or md5 of a string of bytes,
5705 // or as a "tree" where each chunk of the string is hashed and then those
5706 // hashes are put into a (much smaller) string which is hashed with sha1.
5707 // We compute a checksum over the entire file because that is simplest.
5710 Build_id_task_runner::run(Workqueue* workqueue, const Task*)
5712 Task_token* post_hash_tasks_blocker = new Task_token(true);
5713 const Layout* layout = this->layout_;
5714 Output_file* of = this->of_;
5715 const size_t filesize = (layout->output_file_size() <= 0 ? 0
5716 : static_cast<size_t>(layout->output_file_size()));
5717 unsigned char* array_of_hashes = NULL;
5718 size_t size_of_hashes = 0;
5720 if (strcmp(this->options_->build_id(), "tree") == 0
5721 && this->options_->build_id_chunk_size_for_treehash() > 0
5723 && (filesize >= this->options_->build_id_min_file_size_for_treehash()))
5725 static const size_t MD5_OUTPUT_SIZE_IN_BYTES = 16;
5726 const size_t chunk_size =
5727 this->options_->build_id_chunk_size_for_treehash();
5728 const size_t num_hashes = ((filesize - 1) / chunk_size) + 1;
5729 post_hash_tasks_blocker->add_blockers(num_hashes);
5730 size_of_hashes = num_hashes * MD5_OUTPUT_SIZE_IN_BYTES;
5731 array_of_hashes = new unsigned char[size_of_hashes];
5732 unsigned char *dst = array_of_hashes;
5733 for (size_t i = 0, src_offset = 0; i < num_hashes;
5734 i++, dst += MD5_OUTPUT_SIZE_IN_BYTES, src_offset += chunk_size)
5736 size_t size = std::min(chunk_size, filesize - src_offset);
5737 workqueue->queue(new Hash_task(of,
5741 post_hash_tasks_blocker));
5745 // Queue the final task to write the build id and close the output file.
5746 workqueue->queue(new Task_function(new Close_task_runner(this->options_,
5751 post_hash_tasks_blocker,
5752 "Task_function Close_task_runner"));
5755 // Close_task_runner methods.
5757 // Finish up the build ID computation, if necessary, and write a binary file,
5758 // if necessary. Then close the output file.
5761 Close_task_runner::run(Workqueue*, const Task*)
5763 // At this point the multi-threaded part of the build ID computation,
5764 // if any, is done. See Build_id_task_runner.
5765 this->layout_->write_build_id(this->of_, this->array_of_hashes_,
5766 this->size_of_hashes_);
5768 // If we've been asked to create a binary file, we do so here.
5769 if (this->options_->oformat_enum() != General_options::OBJECT_FORMAT_ELF)
5770 this->layout_->write_binary(this->of_);
5775 // Instantiate the templates we need. We could use the configure
5776 // script to restrict this to only the ones for implemented targets.
5778 #ifdef HAVE_TARGET_32_LITTLE
5781 Layout::init_fixed_output_section<32, false>(
5783 elfcpp::Shdr<32, false>& shdr);
5786 #ifdef HAVE_TARGET_32_BIG
5789 Layout::init_fixed_output_section<32, true>(
5791 elfcpp::Shdr<32, true>& shdr);
5794 #ifdef HAVE_TARGET_64_LITTLE
5797 Layout::init_fixed_output_section<64, false>(
5799 elfcpp::Shdr<64, false>& shdr);
5802 #ifdef HAVE_TARGET_64_BIG
5805 Layout::init_fixed_output_section<64, true>(
5807 elfcpp::Shdr<64, true>& shdr);
5810 #ifdef HAVE_TARGET_32_LITTLE
5813 Layout::layout<32, false>(Sized_relobj_file<32, false>* object,
5816 const elfcpp::Shdr<32, false>& shdr,
5817 unsigned int, unsigned int, off_t*);
5820 #ifdef HAVE_TARGET_32_BIG
5823 Layout::layout<32, true>(Sized_relobj_file<32, true>* object,
5826 const elfcpp::Shdr<32, true>& shdr,
5827 unsigned int, unsigned int, off_t*);
5830 #ifdef HAVE_TARGET_64_LITTLE
5833 Layout::layout<64, false>(Sized_relobj_file<64, false>* object,
5836 const elfcpp::Shdr<64, false>& shdr,
5837 unsigned int, unsigned int, off_t*);
5840 #ifdef HAVE_TARGET_64_BIG
5843 Layout::layout<64, true>(Sized_relobj_file<64, true>* object,
5846 const elfcpp::Shdr<64, true>& shdr,
5847 unsigned int, unsigned int, off_t*);
5850 #ifdef HAVE_TARGET_32_LITTLE
5853 Layout::layout_reloc<32, false>(Sized_relobj_file<32, false>* object,
5854 unsigned int reloc_shndx,
5855 const elfcpp::Shdr<32, false>& shdr,
5856 Output_section* data_section,
5857 Relocatable_relocs* rr);
5860 #ifdef HAVE_TARGET_32_BIG
5863 Layout::layout_reloc<32, true>(Sized_relobj_file<32, true>* object,
5864 unsigned int reloc_shndx,
5865 const elfcpp::Shdr<32, true>& shdr,
5866 Output_section* data_section,
5867 Relocatable_relocs* rr);
5870 #ifdef HAVE_TARGET_64_LITTLE
5873 Layout::layout_reloc<64, false>(Sized_relobj_file<64, false>* object,
5874 unsigned int reloc_shndx,
5875 const elfcpp::Shdr<64, false>& shdr,
5876 Output_section* data_section,
5877 Relocatable_relocs* rr);
5880 #ifdef HAVE_TARGET_64_BIG
5883 Layout::layout_reloc<64, true>(Sized_relobj_file<64, true>* object,
5884 unsigned int reloc_shndx,
5885 const elfcpp::Shdr<64, true>& shdr,
5886 Output_section* data_section,
5887 Relocatable_relocs* rr);
5890 #ifdef HAVE_TARGET_32_LITTLE
5893 Layout::layout_group<32, false>(Symbol_table* symtab,
5894 Sized_relobj_file<32, false>* object,
5896 const char* group_section_name,
5897 const char* signature,
5898 const elfcpp::Shdr<32, false>& shdr,
5899 elfcpp::Elf_Word flags,
5900 std::vector<unsigned int>* shndxes);
5903 #ifdef HAVE_TARGET_32_BIG
5906 Layout::layout_group<32, true>(Symbol_table* symtab,
5907 Sized_relobj_file<32, true>* object,
5909 const char* group_section_name,
5910 const char* signature,
5911 const elfcpp::Shdr<32, true>& shdr,
5912 elfcpp::Elf_Word flags,
5913 std::vector<unsigned int>* shndxes);
5916 #ifdef HAVE_TARGET_64_LITTLE
5919 Layout::layout_group<64, false>(Symbol_table* symtab,
5920 Sized_relobj_file<64, false>* object,
5922 const char* group_section_name,
5923 const char* signature,
5924 const elfcpp::Shdr<64, false>& shdr,
5925 elfcpp::Elf_Word flags,
5926 std::vector<unsigned int>* shndxes);
5929 #ifdef HAVE_TARGET_64_BIG
5932 Layout::layout_group<64, true>(Symbol_table* symtab,
5933 Sized_relobj_file<64, true>* object,
5935 const char* group_section_name,
5936 const char* signature,
5937 const elfcpp::Shdr<64, true>& shdr,
5938 elfcpp::Elf_Word flags,
5939 std::vector<unsigned int>* shndxes);
5942 #ifdef HAVE_TARGET_32_LITTLE
5945 Layout::layout_eh_frame<32, false>(Sized_relobj_file<32, false>* object,
5946 const unsigned char* symbols,
5948 const unsigned char* symbol_names,
5949 off_t symbol_names_size,
5951 const elfcpp::Shdr<32, false>& shdr,
5952 unsigned int reloc_shndx,
5953 unsigned int reloc_type,
5957 #ifdef HAVE_TARGET_32_BIG
5960 Layout::layout_eh_frame<32, true>(Sized_relobj_file<32, true>* object,
5961 const unsigned char* symbols,
5963 const unsigned char* symbol_names,
5964 off_t symbol_names_size,
5966 const elfcpp::Shdr<32, true>& shdr,
5967 unsigned int reloc_shndx,
5968 unsigned int reloc_type,
5972 #ifdef HAVE_TARGET_64_LITTLE
5975 Layout::layout_eh_frame<64, false>(Sized_relobj_file<64, false>* object,
5976 const unsigned char* symbols,
5978 const unsigned char* symbol_names,
5979 off_t symbol_names_size,
5981 const elfcpp::Shdr<64, false>& shdr,
5982 unsigned int reloc_shndx,
5983 unsigned int reloc_type,
5987 #ifdef HAVE_TARGET_64_BIG
5990 Layout::layout_eh_frame<64, true>(Sized_relobj_file<64, true>* object,
5991 const unsigned char* symbols,
5993 const unsigned char* symbol_names,
5994 off_t symbol_names_size,
5996 const elfcpp::Shdr<64, true>& shdr,
5997 unsigned int reloc_shndx,
5998 unsigned int reloc_type,
6002 #ifdef HAVE_TARGET_32_LITTLE
6005 Layout::add_to_gdb_index(bool is_type_unit,
6006 Sized_relobj<32, false>* object,
6007 const unsigned char* symbols,
6010 unsigned int reloc_shndx,
6011 unsigned int reloc_type);
6014 #ifdef HAVE_TARGET_32_BIG
6017 Layout::add_to_gdb_index(bool is_type_unit,
6018 Sized_relobj<32, true>* object,
6019 const unsigned char* symbols,
6022 unsigned int reloc_shndx,
6023 unsigned int reloc_type);
6026 #ifdef HAVE_TARGET_64_LITTLE
6029 Layout::add_to_gdb_index(bool is_type_unit,
6030 Sized_relobj<64, false>* object,
6031 const unsigned char* symbols,
6034 unsigned int reloc_shndx,
6035 unsigned int reloc_type);
6038 #ifdef HAVE_TARGET_64_BIG
6041 Layout::add_to_gdb_index(bool is_type_unit,
6042 Sized_relobj<64, true>* object,
6043 const unsigned char* symbols,
6046 unsigned int reloc_shndx,
6047 unsigned int reloc_type);
6050 } // End namespace gold.