1 // layout.cc -- lay out output file sections for gold
3 // Copyright (C) 2006-2017 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 // Remove .eh_frame information for a PLT. FDEs using the CIE must
1585 // be removed in reverse order to the order they were added.
1588 Layout::remove_eh_frame_for_plt(Output_data* plt, const unsigned char* cie_data,
1589 size_t cie_length, const unsigned char* fde_data,
1592 if (parameters->incremental())
1594 // FIXME: Maybe this could work some day....
1597 this->eh_frame_data_->remove_ehframe_for_plt(plt, cie_data, cie_length,
1598 fde_data, fde_length);
1601 // Scan a .debug_info or .debug_types section, and add summary
1602 // information to the .gdb_index section.
1604 template<int size, bool big_endian>
1606 Layout::add_to_gdb_index(bool is_type_unit,
1607 Sized_relobj<size, big_endian>* object,
1608 const unsigned char* symbols,
1611 unsigned int reloc_shndx,
1612 unsigned int reloc_type)
1614 if (this->gdb_index_data_ == NULL)
1616 Output_section* os = this->choose_output_section(NULL, ".gdb_index",
1617 elfcpp::SHT_PROGBITS, 0,
1618 false, ORDER_INVALID,
1619 false, false, false);
1623 this->gdb_index_data_ = new Gdb_index(os);
1624 os->add_output_section_data(this->gdb_index_data_);
1625 os->set_after_input_sections();
1628 this->gdb_index_data_->scan_debug_info(is_type_unit, object, symbols,
1629 symbols_size, shndx, reloc_shndx,
1633 // Add POSD to an output section using NAME, TYPE, and FLAGS. Return
1634 // the output section.
1637 Layout::add_output_section_data(const char* name, elfcpp::Elf_Word type,
1638 elfcpp::Elf_Xword flags,
1639 Output_section_data* posd,
1640 Output_section_order order, bool is_relro)
1642 Output_section* os = this->choose_output_section(NULL, name, type, flags,
1643 false, order, is_relro,
1646 os->add_output_section_data(posd);
1650 // Map section flags to segment flags.
1653 Layout::section_flags_to_segment(elfcpp::Elf_Xword flags)
1655 elfcpp::Elf_Word ret = elfcpp::PF_R;
1656 if ((flags & elfcpp::SHF_WRITE) != 0)
1657 ret |= elfcpp::PF_W;
1658 if ((flags & elfcpp::SHF_EXECINSTR) != 0)
1659 ret |= elfcpp::PF_X;
1663 // Make a new Output_section, and attach it to segments as
1664 // appropriate. ORDER is the order in which this section should
1665 // appear in the output segment. IS_RELRO is true if this is a relro
1666 // (read-only after relocations) section.
1669 Layout::make_output_section(const char* name, elfcpp::Elf_Word type,
1670 elfcpp::Elf_Xword flags,
1671 Output_section_order order, bool is_relro)
1674 if ((flags & elfcpp::SHF_ALLOC) == 0
1675 && strcmp(parameters->options().compress_debug_sections(), "none") != 0
1676 && is_compressible_debug_section(name))
1677 os = new Output_compressed_section(¶meters->options(), name, type,
1679 else if ((flags & elfcpp::SHF_ALLOC) == 0
1680 && parameters->options().strip_debug_non_line()
1681 && strcmp(".debug_abbrev", name) == 0)
1683 os = this->debug_abbrev_ = new Output_reduced_debug_abbrev_section(
1685 if (this->debug_info_)
1686 this->debug_info_->set_abbreviations(this->debug_abbrev_);
1688 else if ((flags & elfcpp::SHF_ALLOC) == 0
1689 && parameters->options().strip_debug_non_line()
1690 && strcmp(".debug_info", name) == 0)
1692 os = this->debug_info_ = new Output_reduced_debug_info_section(
1694 if (this->debug_abbrev_)
1695 this->debug_info_->set_abbreviations(this->debug_abbrev_);
1699 // Sometimes .init_array*, .preinit_array* and .fini_array* do
1700 // not have correct section types. Force them here.
1701 if (type == elfcpp::SHT_PROGBITS)
1703 if (is_prefix_of(".init_array", name))
1704 type = elfcpp::SHT_INIT_ARRAY;
1705 else if (is_prefix_of(".preinit_array", name))
1706 type = elfcpp::SHT_PREINIT_ARRAY;
1707 else if (is_prefix_of(".fini_array", name))
1708 type = elfcpp::SHT_FINI_ARRAY;
1711 // FIXME: const_cast is ugly.
1712 Target* target = const_cast<Target*>(¶meters->target());
1713 os = target->make_output_section(name, type, flags);
1716 // With -z relro, we have to recognize the special sections by name.
1717 // There is no other way.
1718 bool is_relro_local = false;
1719 if (!this->script_options_->saw_sections_clause()
1720 && parameters->options().relro()
1721 && (flags & elfcpp::SHF_ALLOC) != 0
1722 && (flags & elfcpp::SHF_WRITE) != 0)
1724 if (type == elfcpp::SHT_PROGBITS)
1726 if ((flags & elfcpp::SHF_TLS) != 0)
1728 else if (strcmp(name, ".data.rel.ro") == 0)
1730 else if (strcmp(name, ".data.rel.ro.local") == 0)
1733 is_relro_local = true;
1735 else if (strcmp(name, ".ctors") == 0
1736 || strcmp(name, ".dtors") == 0
1737 || strcmp(name, ".jcr") == 0)
1740 else if (type == elfcpp::SHT_INIT_ARRAY
1741 || type == elfcpp::SHT_FINI_ARRAY
1742 || type == elfcpp::SHT_PREINIT_ARRAY)
1749 if (order == ORDER_INVALID && (flags & elfcpp::SHF_ALLOC) != 0)
1750 order = this->default_section_order(os, is_relro_local);
1752 os->set_order(order);
1754 parameters->target().new_output_section(os);
1756 this->section_list_.push_back(os);
1758 // The GNU linker by default sorts some sections by priority, so we
1759 // do the same. We need to know that this might happen before we
1760 // attach any input sections.
1761 if (!this->script_options_->saw_sections_clause()
1762 && !parameters->options().relocatable()
1763 && (strcmp(name, ".init_array") == 0
1764 || strcmp(name, ".fini_array") == 0
1765 || (!parameters->options().ctors_in_init_array()
1766 && (strcmp(name, ".ctors") == 0
1767 || strcmp(name, ".dtors") == 0))))
1768 os->set_may_sort_attached_input_sections();
1770 // The GNU linker by default sorts .text.{unlikely,exit,startup,hot}
1771 // sections before other .text sections. We are compatible. We
1772 // need to know that this might happen before we attach any input
1774 if (parameters->options().text_reorder()
1775 && !this->script_options_->saw_sections_clause()
1776 && !this->is_section_ordering_specified()
1777 && !parameters->options().relocatable()
1778 && strcmp(name, ".text") == 0)
1779 os->set_may_sort_attached_input_sections();
1781 // GNU linker sorts section by name with --sort-section=name.
1782 if (strcmp(parameters->options().sort_section(), "name") == 0)
1783 os->set_must_sort_attached_input_sections();
1785 // Check for .stab*str sections, as .stab* sections need to link to
1787 if (type == elfcpp::SHT_STRTAB
1788 && !this->have_stabstr_section_
1789 && strncmp(name, ".stab", 5) == 0
1790 && strcmp(name + strlen(name) - 3, "str") == 0)
1791 this->have_stabstr_section_ = true;
1793 // During a full incremental link, we add patch space to most
1794 // PROGBITS and NOBITS sections. Flag those that may be
1795 // arbitrarily padded.
1796 if ((type == elfcpp::SHT_PROGBITS || type == elfcpp::SHT_NOBITS)
1797 && order != ORDER_INTERP
1798 && order != ORDER_INIT
1799 && order != ORDER_PLT
1800 && order != ORDER_FINI
1801 && order != ORDER_RELRO_LAST
1802 && order != ORDER_NON_RELRO_FIRST
1803 && strcmp(name, ".eh_frame") != 0
1804 && strcmp(name, ".ctors") != 0
1805 && strcmp(name, ".dtors") != 0
1806 && strcmp(name, ".jcr") != 0)
1808 os->set_is_patch_space_allowed();
1810 // Certain sections require "holes" to be filled with
1811 // specific fill patterns. These fill patterns may have
1812 // a minimum size, so we must prevent allocations from the
1813 // free list that leave a hole smaller than the minimum.
1814 if (strcmp(name, ".debug_info") == 0)
1815 os->set_free_space_fill(new Output_fill_debug_info(false));
1816 else if (strcmp(name, ".debug_types") == 0)
1817 os->set_free_space_fill(new Output_fill_debug_info(true));
1818 else if (strcmp(name, ".debug_line") == 0)
1819 os->set_free_space_fill(new Output_fill_debug_line());
1822 // If we have already attached the sections to segments, then we
1823 // need to attach this one now. This happens for sections created
1824 // directly by the linker.
1825 if (this->sections_are_attached_)
1826 this->attach_section_to_segment(¶meters->target(), os);
1831 // Return the default order in which a section should be placed in an
1832 // output segment. This function captures a lot of the ideas in
1833 // ld/scripttempl/elf.sc in the GNU linker. Note that the order of a
1834 // linker created section is normally set when the section is created;
1835 // this function is used for input sections.
1837 Output_section_order
1838 Layout::default_section_order(Output_section* os, bool is_relro_local)
1840 gold_assert((os->flags() & elfcpp::SHF_ALLOC) != 0);
1841 bool is_write = (os->flags() & elfcpp::SHF_WRITE) != 0;
1842 bool is_execinstr = (os->flags() & elfcpp::SHF_EXECINSTR) != 0;
1843 bool is_bss = false;
1848 case elfcpp::SHT_PROGBITS:
1850 case elfcpp::SHT_NOBITS:
1853 case elfcpp::SHT_RELA:
1854 case elfcpp::SHT_REL:
1856 return ORDER_DYNAMIC_RELOCS;
1858 case elfcpp::SHT_HASH:
1859 case elfcpp::SHT_DYNAMIC:
1860 case elfcpp::SHT_SHLIB:
1861 case elfcpp::SHT_DYNSYM:
1862 case elfcpp::SHT_GNU_HASH:
1863 case elfcpp::SHT_GNU_verdef:
1864 case elfcpp::SHT_GNU_verneed:
1865 case elfcpp::SHT_GNU_versym:
1867 return ORDER_DYNAMIC_LINKER;
1869 case elfcpp::SHT_NOTE:
1870 return is_write ? ORDER_RW_NOTE : ORDER_RO_NOTE;
1873 if ((os->flags() & elfcpp::SHF_TLS) != 0)
1874 return is_bss ? ORDER_TLS_BSS : ORDER_TLS_DATA;
1876 if (!is_bss && !is_write)
1880 if (strcmp(os->name(), ".init") == 0)
1882 else if (strcmp(os->name(), ".fini") == 0)
1885 return is_execinstr ? ORDER_TEXT : ORDER_READONLY;
1889 return is_relro_local ? ORDER_RELRO_LOCAL : ORDER_RELRO;
1891 if (os->is_small_section())
1892 return is_bss ? ORDER_SMALL_BSS : ORDER_SMALL_DATA;
1893 if (os->is_large_section())
1894 return is_bss ? ORDER_LARGE_BSS : ORDER_LARGE_DATA;
1896 return is_bss ? ORDER_BSS : ORDER_DATA;
1899 // Attach output sections to segments. This is called after we have
1900 // seen all the input sections.
1903 Layout::attach_sections_to_segments(const Target* target)
1905 for (Section_list::iterator p = this->section_list_.begin();
1906 p != this->section_list_.end();
1908 this->attach_section_to_segment(target, *p);
1910 this->sections_are_attached_ = true;
1913 // Attach an output section to a segment.
1916 Layout::attach_section_to_segment(const Target* target, Output_section* os)
1918 if ((os->flags() & elfcpp::SHF_ALLOC) == 0)
1919 this->unattached_section_list_.push_back(os);
1921 this->attach_allocated_section_to_segment(target, os);
1924 // Attach an allocated output section to a segment.
1927 Layout::attach_allocated_section_to_segment(const Target* target,
1930 elfcpp::Elf_Xword flags = os->flags();
1931 gold_assert((flags & elfcpp::SHF_ALLOC) != 0);
1933 if (parameters->options().relocatable())
1936 // If we have a SECTIONS clause, we can't handle the attachment to
1937 // segments until after we've seen all the sections.
1938 if (this->script_options_->saw_sections_clause())
1941 gold_assert(!this->script_options_->saw_phdrs_clause());
1943 // This output section goes into a PT_LOAD segment.
1945 elfcpp::Elf_Word seg_flags = Layout::section_flags_to_segment(flags);
1947 // If this output section's segment has extra flags that need to be set,
1948 // coming from a linker plugin, do that.
1949 seg_flags |= os->extra_segment_flags();
1951 // Check for --section-start.
1953 bool is_address_set = parameters->options().section_start(os->name(), &addr);
1955 // In general the only thing we really care about for PT_LOAD
1956 // segments is whether or not they are writable or executable,
1957 // so that is how we search for them.
1958 // Large data sections also go into their own PT_LOAD segment.
1959 // People who need segments sorted on some other basis will
1960 // have to use a linker script.
1962 Segment_list::const_iterator p;
1963 if (!os->is_unique_segment())
1965 for (p = this->segment_list_.begin();
1966 p != this->segment_list_.end();
1969 if ((*p)->type() != elfcpp::PT_LOAD)
1971 if ((*p)->is_unique_segment())
1973 if (!parameters->options().omagic()
1974 && ((*p)->flags() & elfcpp::PF_W) != (seg_flags & elfcpp::PF_W))
1976 if ((target->isolate_execinstr() || parameters->options().rosegment())
1977 && ((*p)->flags() & elfcpp::PF_X) != (seg_flags & elfcpp::PF_X))
1979 // If -Tbss was specified, we need to separate the data and BSS
1981 if (parameters->options().user_set_Tbss())
1983 if ((os->type() == elfcpp::SHT_NOBITS)
1984 == (*p)->has_any_data_sections())
1987 if (os->is_large_data_section() && !(*p)->is_large_data_segment())
1992 if ((*p)->are_addresses_set())
1995 (*p)->add_initial_output_data(os);
1996 (*p)->update_flags_for_output_section(seg_flags);
1997 (*p)->set_addresses(addr, addr);
2001 (*p)->add_output_section_to_load(this, os, seg_flags);
2006 if (p == this->segment_list_.end()
2007 || os->is_unique_segment())
2009 Output_segment* oseg = this->make_output_segment(elfcpp::PT_LOAD,
2011 if (os->is_large_data_section())
2012 oseg->set_is_large_data_segment();
2013 oseg->add_output_section_to_load(this, os, seg_flags);
2015 oseg->set_addresses(addr, addr);
2016 // Check if segment should be marked unique. For segments marked
2017 // unique by linker plugins, set the new alignment if specified.
2018 if (os->is_unique_segment())
2020 oseg->set_is_unique_segment();
2021 if (os->segment_alignment() != 0)
2022 oseg->set_minimum_p_align(os->segment_alignment());
2026 // If we see a loadable SHT_NOTE section, we create a PT_NOTE
2028 if (os->type() == elfcpp::SHT_NOTE)
2030 // See if we already have an equivalent PT_NOTE segment.
2031 for (p = this->segment_list_.begin();
2032 p != segment_list_.end();
2035 if ((*p)->type() == elfcpp::PT_NOTE
2036 && (((*p)->flags() & elfcpp::PF_W)
2037 == (seg_flags & elfcpp::PF_W)))
2039 (*p)->add_output_section_to_nonload(os, seg_flags);
2044 if (p == this->segment_list_.end())
2046 Output_segment* oseg = this->make_output_segment(elfcpp::PT_NOTE,
2048 oseg->add_output_section_to_nonload(os, seg_flags);
2052 // If we see a loadable SHF_TLS section, we create a PT_TLS
2053 // segment. There can only be one such segment.
2054 if ((flags & elfcpp::SHF_TLS) != 0)
2056 if (this->tls_segment_ == NULL)
2057 this->make_output_segment(elfcpp::PT_TLS, seg_flags);
2058 this->tls_segment_->add_output_section_to_nonload(os, seg_flags);
2061 // If -z relro is in effect, and we see a relro section, we create a
2062 // PT_GNU_RELRO segment. There can only be one such segment.
2063 if (os->is_relro() && parameters->options().relro())
2065 gold_assert(seg_flags == (elfcpp::PF_R | elfcpp::PF_W));
2066 if (this->relro_segment_ == NULL)
2067 this->make_output_segment(elfcpp::PT_GNU_RELRO, seg_flags);
2068 this->relro_segment_->add_output_section_to_nonload(os, seg_flags);
2071 // If we see a section named .interp, put it into a PT_INTERP
2072 // segment. This seems broken to me, but this is what GNU ld does,
2073 // and glibc expects it.
2074 if (strcmp(os->name(), ".interp") == 0
2075 && !this->script_options_->saw_phdrs_clause())
2077 if (this->interp_segment_ == NULL)
2078 this->make_output_segment(elfcpp::PT_INTERP, seg_flags);
2080 gold_warning(_("multiple '.interp' sections in input files "
2081 "may cause confusing PT_INTERP segment"));
2082 this->interp_segment_->add_output_section_to_nonload(os, seg_flags);
2086 // Make an output section for a script.
2089 Layout::make_output_section_for_script(
2091 Script_sections::Section_type section_type)
2093 name = this->namepool_.add(name, false, NULL);
2094 elfcpp::Elf_Xword sh_flags = elfcpp::SHF_ALLOC;
2095 if (section_type == Script_sections::ST_NOLOAD)
2097 Output_section* os = this->make_output_section(name, elfcpp::SHT_PROGBITS,
2098 sh_flags, ORDER_INVALID,
2100 os->set_found_in_sections_clause();
2101 if (section_type == Script_sections::ST_NOLOAD)
2102 os->set_is_noload();
2106 // Return the number of segments we expect to see.
2109 Layout::expected_segment_count() const
2111 size_t ret = this->segment_list_.size();
2113 // If we didn't see a SECTIONS clause in a linker script, we should
2114 // already have the complete list of segments. Otherwise we ask the
2115 // SECTIONS clause how many segments it expects, and add in the ones
2116 // we already have (PT_GNU_STACK, PT_GNU_EH_FRAME, etc.)
2118 if (!this->script_options_->saw_sections_clause())
2122 const Script_sections* ss = this->script_options_->script_sections();
2123 return ret + ss->expected_segment_count(this);
2127 // Handle the .note.GNU-stack section at layout time. SEEN_GNU_STACK
2128 // is whether we saw a .note.GNU-stack section in the object file.
2129 // GNU_STACK_FLAGS is the section flags. The flags give the
2130 // protection required for stack memory. We record this in an
2131 // executable as a PT_GNU_STACK segment. If an object file does not
2132 // have a .note.GNU-stack segment, we must assume that it is an old
2133 // object. On some targets that will force an executable stack.
2136 Layout::layout_gnu_stack(bool seen_gnu_stack, uint64_t gnu_stack_flags,
2139 if (!seen_gnu_stack)
2141 this->input_without_gnu_stack_note_ = true;
2142 if (parameters->options().warn_execstack()
2143 && parameters->target().is_default_stack_executable())
2144 gold_warning(_("%s: missing .note.GNU-stack section"
2145 " implies executable stack"),
2146 obj->name().c_str());
2150 this->input_with_gnu_stack_note_ = true;
2151 if ((gnu_stack_flags & elfcpp::SHF_EXECINSTR) != 0)
2153 this->input_requires_executable_stack_ = true;
2154 if (parameters->options().warn_execstack())
2155 gold_warning(_("%s: requires executable stack"),
2156 obj->name().c_str());
2161 // Create automatic note sections.
2164 Layout::create_notes()
2166 this->create_gold_note();
2167 this->create_stack_segment();
2168 this->create_build_id();
2171 // Create the dynamic sections which are needed before we read the
2175 Layout::create_initial_dynamic_sections(Symbol_table* symtab)
2177 if (parameters->doing_static_link())
2180 this->dynamic_section_ = this->choose_output_section(NULL, ".dynamic",
2181 elfcpp::SHT_DYNAMIC,
2183 | elfcpp::SHF_WRITE),
2185 true, false, false);
2187 // A linker script may discard .dynamic, so check for NULL.
2188 if (this->dynamic_section_ != NULL)
2190 this->dynamic_symbol_ =
2191 symtab->define_in_output_data("_DYNAMIC", NULL,
2192 Symbol_table::PREDEFINED,
2193 this->dynamic_section_, 0, 0,
2194 elfcpp::STT_OBJECT, elfcpp::STB_LOCAL,
2195 elfcpp::STV_HIDDEN, 0, false, false);
2197 this->dynamic_data_ = new Output_data_dynamic(&this->dynpool_);
2199 this->dynamic_section_->add_output_section_data(this->dynamic_data_);
2203 // For each output section whose name can be represented as C symbol,
2204 // define __start and __stop symbols for the section. This is a GNU
2208 Layout::define_section_symbols(Symbol_table* symtab)
2210 for (Section_list::const_iterator p = this->section_list_.begin();
2211 p != this->section_list_.end();
2214 const char* const name = (*p)->name();
2215 if (is_cident(name))
2217 const std::string name_string(name);
2218 const std::string start_name(cident_section_start_prefix
2220 const std::string stop_name(cident_section_stop_prefix
2223 symtab->define_in_output_data(start_name.c_str(),
2225 Symbol_table::PREDEFINED,
2231 elfcpp::STV_DEFAULT,
2233 false, // offset_is_from_end
2234 true); // only_if_ref
2236 symtab->define_in_output_data(stop_name.c_str(),
2238 Symbol_table::PREDEFINED,
2244 elfcpp::STV_DEFAULT,
2246 true, // offset_is_from_end
2247 true); // only_if_ref
2252 // Define symbols for group signatures.
2255 Layout::define_group_signatures(Symbol_table* symtab)
2257 for (Group_signatures::iterator p = this->group_signatures_.begin();
2258 p != this->group_signatures_.end();
2261 Symbol* sym = symtab->lookup(p->signature, NULL);
2263 p->section->set_info_symndx(sym);
2266 // Force the name of the group section to the group
2267 // signature, and use the group's section symbol as the
2268 // signature symbol.
2269 if (strcmp(p->section->name(), p->signature) != 0)
2271 const char* name = this->namepool_.add(p->signature,
2273 p->section->set_name(name);
2275 p->section->set_needs_symtab_index();
2276 p->section->set_info_section_symndx(p->section);
2280 this->group_signatures_.clear();
2283 // Find the first read-only PT_LOAD segment, creating one if
2287 Layout::find_first_load_seg(const Target* target)
2289 Output_segment* best = NULL;
2290 for (Segment_list::const_iterator p = this->segment_list_.begin();
2291 p != this->segment_list_.end();
2294 if ((*p)->type() == elfcpp::PT_LOAD
2295 && ((*p)->flags() & elfcpp::PF_R) != 0
2296 && (parameters->options().omagic()
2297 || ((*p)->flags() & elfcpp::PF_W) == 0)
2298 && (!target->isolate_execinstr()
2299 || ((*p)->flags() & elfcpp::PF_X) == 0))
2301 if (best == NULL || this->segment_precedes(*p, best))
2308 gold_assert(!this->script_options_->saw_phdrs_clause());
2310 Output_segment* load_seg = this->make_output_segment(elfcpp::PT_LOAD,
2315 // Save states of all current output segments. Store saved states
2316 // in SEGMENT_STATES.
2319 Layout::save_segments(Segment_states* segment_states)
2321 for (Segment_list::const_iterator p = this->segment_list_.begin();
2322 p != this->segment_list_.end();
2325 Output_segment* segment = *p;
2327 Output_segment* copy = new Output_segment(*segment);
2328 (*segment_states)[segment] = copy;
2332 // Restore states of output segments and delete any segment not found in
2336 Layout::restore_segments(const Segment_states* segment_states)
2338 // Go through the segment list and remove any segment added in the
2340 this->tls_segment_ = NULL;
2341 this->relro_segment_ = NULL;
2342 Segment_list::iterator list_iter = this->segment_list_.begin();
2343 while (list_iter != this->segment_list_.end())
2345 Output_segment* segment = *list_iter;
2346 Segment_states::const_iterator states_iter =
2347 segment_states->find(segment);
2348 if (states_iter != segment_states->end())
2350 const Output_segment* copy = states_iter->second;
2351 // Shallow copy to restore states.
2354 // Also fix up TLS and RELRO segment pointers as appropriate.
2355 if (segment->type() == elfcpp::PT_TLS)
2356 this->tls_segment_ = segment;
2357 else if (segment->type() == elfcpp::PT_GNU_RELRO)
2358 this->relro_segment_ = segment;
2364 list_iter = this->segment_list_.erase(list_iter);
2365 // This is a segment created during section layout. It should be
2366 // safe to remove it since we should have removed all pointers to it.
2372 // Clean up after relaxation so that sections can be laid out again.
2375 Layout::clean_up_after_relaxation()
2377 // Restore the segments to point state just prior to the relaxation loop.
2378 Script_sections* script_section = this->script_options_->script_sections();
2379 script_section->release_segments();
2380 this->restore_segments(this->segment_states_);
2382 // Reset section addresses and file offsets
2383 for (Section_list::iterator p = this->section_list_.begin();
2384 p != this->section_list_.end();
2387 (*p)->restore_states();
2389 // If an input section changes size because of relaxation,
2390 // we need to adjust the section offsets of all input sections.
2391 // after such a section.
2392 if ((*p)->section_offsets_need_adjustment())
2393 (*p)->adjust_section_offsets();
2395 (*p)->reset_address_and_file_offset();
2398 // Reset special output object address and file offsets.
2399 for (Data_list::iterator p = this->special_output_list_.begin();
2400 p != this->special_output_list_.end();
2402 (*p)->reset_address_and_file_offset();
2404 // A linker script may have created some output section data objects.
2405 // They are useless now.
2406 for (Output_section_data_list::const_iterator p =
2407 this->script_output_section_data_list_.begin();
2408 p != this->script_output_section_data_list_.end();
2411 this->script_output_section_data_list_.clear();
2413 // Special-case fill output objects are recreated each time through
2414 // the relaxation loop.
2415 this->reset_relax_output();
2419 Layout::reset_relax_output()
2421 for (Data_list::const_iterator p = this->relax_output_list_.begin();
2422 p != this->relax_output_list_.end();
2425 this->relax_output_list_.clear();
2428 // Prepare for relaxation.
2431 Layout::prepare_for_relaxation()
2433 // Create an relaxation debug check if in debugging mode.
2434 if (is_debugging_enabled(DEBUG_RELAXATION))
2435 this->relaxation_debug_check_ = new Relaxation_debug_check();
2437 // Save segment states.
2438 this->segment_states_ = new Segment_states();
2439 this->save_segments(this->segment_states_);
2441 for(Section_list::const_iterator p = this->section_list_.begin();
2442 p != this->section_list_.end();
2444 (*p)->save_states();
2446 if (is_debugging_enabled(DEBUG_RELAXATION))
2447 this->relaxation_debug_check_->check_output_data_for_reset_values(
2448 this->section_list_, this->special_output_list_,
2449 this->relax_output_list_);
2451 // Also enable recording of output section data from scripts.
2452 this->record_output_section_data_from_script_ = true;
2455 // If the user set the address of the text segment, that may not be
2456 // compatible with putting the segment headers and file headers into
2457 // that segment. For isolate_execinstr() targets, it's the rodata
2458 // segment rather than text where we might put the headers.
2460 load_seg_unusable_for_headers(const Target* target)
2462 const General_options& options = parameters->options();
2463 if (target->isolate_execinstr())
2464 return (options.user_set_Trodata_segment()
2465 && options.Trodata_segment() % target->abi_pagesize() != 0);
2467 return (options.user_set_Ttext()
2468 && options.Ttext() % target->abi_pagesize() != 0);
2471 // Relaxation loop body: If target has no relaxation, this runs only once
2472 // Otherwise, the target relaxation hook is called at the end of
2473 // each iteration. If the hook returns true, it means re-layout of
2474 // section is required.
2476 // The number of segments created by a linking script without a PHDRS
2477 // clause may be affected by section sizes and alignments. There is
2478 // a remote chance that relaxation causes different number of PT_LOAD
2479 // segments are created and sections are attached to different segments.
2480 // Therefore, we always throw away all segments created during section
2481 // layout. In order to be able to restart the section layout, we keep
2482 // a copy of the segment list right before the relaxation loop and use
2483 // that to restore the segments.
2485 // PASS is the current relaxation pass number.
2486 // SYMTAB is a symbol table.
2487 // PLOAD_SEG is the address of a pointer for the load segment.
2488 // PHDR_SEG is a pointer to the PHDR segment.
2489 // SEGMENT_HEADERS points to the output segment header.
2490 // FILE_HEADER points to the output file header.
2491 // PSHNDX is the address to store the output section index.
2494 Layout::relaxation_loop_body(
2497 Symbol_table* symtab,
2498 Output_segment** pload_seg,
2499 Output_segment* phdr_seg,
2500 Output_segment_headers* segment_headers,
2501 Output_file_header* file_header,
2502 unsigned int* pshndx)
2504 // If this is not the first iteration, we need to clean up after
2505 // relaxation so that we can lay out the sections again.
2507 this->clean_up_after_relaxation();
2509 // If there is a SECTIONS clause, put all the input sections into
2510 // the required order.
2511 Output_segment* load_seg;
2512 if (this->script_options_->saw_sections_clause())
2513 load_seg = this->set_section_addresses_from_script(symtab);
2514 else if (parameters->options().relocatable())
2517 load_seg = this->find_first_load_seg(target);
2519 if (parameters->options().oformat_enum()
2520 != General_options::OBJECT_FORMAT_ELF)
2523 if (load_seg_unusable_for_headers(target))
2529 gold_assert(phdr_seg == NULL
2531 || this->script_options_->saw_sections_clause());
2533 // If the address of the load segment we found has been set by
2534 // --section-start rather than by a script, then adjust the VMA and
2535 // LMA downward if possible to include the file and section headers.
2536 uint64_t header_gap = 0;
2537 if (load_seg != NULL
2538 && load_seg->are_addresses_set()
2539 && !this->script_options_->saw_sections_clause()
2540 && !parameters->options().relocatable())
2542 file_header->finalize_data_size();
2543 segment_headers->finalize_data_size();
2544 size_t sizeof_headers = (file_header->data_size()
2545 + segment_headers->data_size());
2546 const uint64_t abi_pagesize = target->abi_pagesize();
2547 uint64_t hdr_paddr = load_seg->paddr() - sizeof_headers;
2548 hdr_paddr &= ~(abi_pagesize - 1);
2549 uint64_t subtract = load_seg->paddr() - hdr_paddr;
2550 if (load_seg->paddr() < subtract || load_seg->vaddr() < subtract)
2554 load_seg->set_addresses(load_seg->vaddr() - subtract,
2555 load_seg->paddr() - subtract);
2556 header_gap = subtract - sizeof_headers;
2560 // Lay out the segment headers.
2561 if (!parameters->options().relocatable())
2563 gold_assert(segment_headers != NULL);
2564 if (header_gap != 0 && load_seg != NULL)
2566 Output_data_zero_fill* z = new Output_data_zero_fill(header_gap, 1);
2567 load_seg->add_initial_output_data(z);
2569 if (load_seg != NULL)
2570 load_seg->add_initial_output_data(segment_headers);
2571 if (phdr_seg != NULL)
2572 phdr_seg->add_initial_output_data(segment_headers);
2575 // Lay out the file header.
2576 if (load_seg != NULL)
2577 load_seg->add_initial_output_data(file_header);
2579 if (this->script_options_->saw_phdrs_clause()
2580 && !parameters->options().relocatable())
2582 // Support use of FILEHDRS and PHDRS attachments in a PHDRS
2583 // clause in a linker script.
2584 Script_sections* ss = this->script_options_->script_sections();
2585 ss->put_headers_in_phdrs(file_header, segment_headers);
2588 // We set the output section indexes in set_segment_offsets and
2589 // set_section_indexes.
2592 // Set the file offsets of all the segments, and all the sections
2595 if (!parameters->options().relocatable())
2596 off = this->set_segment_offsets(target, load_seg, pshndx);
2598 off = this->set_relocatable_section_offsets(file_header, pshndx);
2600 // Verify that the dummy relaxation does not change anything.
2601 if (is_debugging_enabled(DEBUG_RELAXATION))
2604 this->relaxation_debug_check_->read_sections(this->section_list_);
2606 this->relaxation_debug_check_->verify_sections(this->section_list_);
2609 *pload_seg = load_seg;
2613 // Search the list of patterns and find the position of the given section
2614 // name in the output section. If the section name matches a glob
2615 // pattern and a non-glob name, then the non-glob position takes
2616 // precedence. Return 0 if no match is found.
2619 Layout::find_section_order_index(const std::string& section_name)
2621 Unordered_map<std::string, unsigned int>::iterator map_it;
2622 map_it = this->input_section_position_.find(section_name);
2623 if (map_it != this->input_section_position_.end())
2624 return map_it->second;
2626 // Absolute match failed. Linear search the glob patterns.
2627 std::vector<std::string>::iterator it;
2628 for (it = this->input_section_glob_.begin();
2629 it != this->input_section_glob_.end();
2632 if (fnmatch((*it).c_str(), section_name.c_str(), FNM_NOESCAPE) == 0)
2634 map_it = this->input_section_position_.find(*it);
2635 gold_assert(map_it != this->input_section_position_.end());
2636 return map_it->second;
2642 // Read the sequence of input sections from the file specified with
2643 // option --section-ordering-file.
2646 Layout::read_layout_from_file()
2648 const char* filename = parameters->options().section_ordering_file();
2654 gold_fatal(_("unable to open --section-ordering-file file %s: %s"),
2655 filename, strerror(errno));
2657 std::getline(in, line); // this chops off the trailing \n, if any
2658 unsigned int position = 1;
2659 this->set_section_ordering_specified();
2663 if (!line.empty() && line[line.length() - 1] == '\r') // Windows
2664 line.resize(line.length() - 1);
2665 // Ignore comments, beginning with '#'
2668 std::getline(in, line);
2671 this->input_section_position_[line] = position;
2672 // Store all glob patterns in a vector.
2673 if (is_wildcard_string(line.c_str()))
2674 this->input_section_glob_.push_back(line);
2676 std::getline(in, line);
2680 // Finalize the layout. When this is called, we have created all the
2681 // output sections and all the output segments which are based on
2682 // input sections. We have several things to do, and we have to do
2683 // them in the right order, so that we get the right results correctly
2686 // 1) Finalize the list of output segments and create the segment
2689 // 2) Finalize the dynamic symbol table and associated sections.
2691 // 3) Determine the final file offset of all the output segments.
2693 // 4) Determine the final file offset of all the SHF_ALLOC output
2696 // 5) Create the symbol table sections and the section name table
2699 // 6) Finalize the symbol table: set symbol values to their final
2700 // value and make a final determination of which symbols are going
2701 // into the output symbol table.
2703 // 7) Create the section table header.
2705 // 8) Determine the final file offset of all the output sections which
2706 // are not SHF_ALLOC, including the section table header.
2708 // 9) Finalize the ELF file header.
2710 // This function returns the size of the output file.
2713 Layout::finalize(const Input_objects* input_objects, Symbol_table* symtab,
2714 Target* target, const Task* task)
2716 unsigned int local_dynamic_count = 0;
2717 unsigned int forced_local_dynamic_count = 0;
2719 target->finalize_sections(this, input_objects, symtab);
2721 this->count_local_symbols(task, input_objects);
2723 this->link_stabs_sections();
2725 Output_segment* phdr_seg = NULL;
2726 if (!parameters->options().relocatable() && !parameters->doing_static_link())
2728 // There was a dynamic object in the link. We need to create
2729 // some information for the dynamic linker.
2731 // Create the PT_PHDR segment which will hold the program
2733 if (!this->script_options_->saw_phdrs_clause())
2734 phdr_seg = this->make_output_segment(elfcpp::PT_PHDR, elfcpp::PF_R);
2736 // Create the dynamic symbol table, including the hash table.
2737 Output_section* dynstr;
2738 std::vector<Symbol*> dynamic_symbols;
2739 Versions versions(*this->script_options()->version_script_info(),
2741 this->create_dynamic_symtab(input_objects, symtab, &dynstr,
2742 &local_dynamic_count,
2743 &forced_local_dynamic_count,
2747 // Create the .interp section to hold the name of the
2748 // interpreter, and put it in a PT_INTERP segment. Don't do it
2749 // if we saw a .interp section in an input file.
2750 if ((!parameters->options().shared()
2751 || parameters->options().dynamic_linker() != NULL)
2752 && this->interp_segment_ == NULL)
2753 this->create_interp(target);
2755 // Finish the .dynamic section to hold the dynamic data, and put
2756 // it in a PT_DYNAMIC segment.
2757 this->finish_dynamic_section(input_objects, symtab);
2759 // We should have added everything we need to the dynamic string
2761 this->dynpool_.set_string_offsets();
2763 // Create the version sections. We can't do this until the
2764 // dynamic string table is complete.
2765 this->create_version_sections(&versions, symtab,
2766 (local_dynamic_count
2767 + forced_local_dynamic_count),
2768 dynamic_symbols, dynstr);
2770 // Set the size of the _DYNAMIC symbol. We can't do this until
2771 // after we call create_version_sections.
2772 this->set_dynamic_symbol_size(symtab);
2775 // Create segment headers.
2776 Output_segment_headers* segment_headers =
2777 (parameters->options().relocatable()
2779 : new Output_segment_headers(this->segment_list_));
2781 // Lay out the file header.
2782 Output_file_header* file_header = new Output_file_header(target, symtab,
2785 this->special_output_list_.push_back(file_header);
2786 if (segment_headers != NULL)
2787 this->special_output_list_.push_back(segment_headers);
2789 // Find approriate places for orphan output sections if we are using
2791 if (this->script_options_->saw_sections_clause())
2792 this->place_orphan_sections_in_script();
2794 Output_segment* load_seg;
2799 // Take a snapshot of the section layout as needed.
2800 if (target->may_relax())
2801 this->prepare_for_relaxation();
2803 // Run the relaxation loop to lay out sections.
2806 off = this->relaxation_loop_body(pass, target, symtab, &load_seg,
2807 phdr_seg, segment_headers, file_header,
2811 while (target->may_relax()
2812 && target->relax(pass, input_objects, symtab, this, task));
2814 // If there is a load segment that contains the file and program headers,
2815 // provide a symbol __ehdr_start pointing there.
2816 // A program can use this to examine itself robustly.
2817 Symbol *ehdr_start = symtab->lookup("__ehdr_start");
2818 if (ehdr_start != NULL && ehdr_start->is_predefined())
2820 if (load_seg != NULL)
2821 ehdr_start->set_output_segment(load_seg, Symbol::SEGMENT_START);
2823 ehdr_start->set_undefined();
2826 // Set the file offsets of all the non-data sections we've seen so
2827 // far which don't have to wait for the input sections. We need
2828 // this in order to finalize local symbols in non-allocated
2830 off = this->set_section_offsets(off, BEFORE_INPUT_SECTIONS_PASS);
2832 // Set the section indexes of all unallocated sections seen so far,
2833 // in case any of them are somehow referenced by a symbol.
2834 shndx = this->set_section_indexes(shndx);
2836 // Create the symbol table sections.
2837 this->create_symtab_sections(input_objects, symtab, shndx, &off,
2838 local_dynamic_count);
2839 if (!parameters->doing_static_link())
2840 this->assign_local_dynsym_offsets(input_objects);
2842 // Process any symbol assignments from a linker script. This must
2843 // be called after the symbol table has been finalized.
2844 this->script_options_->finalize_symbols(symtab, this);
2846 // Create the incremental inputs sections.
2847 if (this->incremental_inputs_)
2849 this->incremental_inputs_->finalize();
2850 this->create_incremental_info_sections(symtab);
2853 // Create the .shstrtab section.
2854 Output_section* shstrtab_section = this->create_shstrtab();
2856 // Set the file offsets of the rest of the non-data sections which
2857 // don't have to wait for the input sections.
2858 off = this->set_section_offsets(off, BEFORE_INPUT_SECTIONS_PASS);
2860 // Now that all sections have been created, set the section indexes
2861 // for any sections which haven't been done yet.
2862 shndx = this->set_section_indexes(shndx);
2864 // Create the section table header.
2865 this->create_shdrs(shstrtab_section, &off);
2867 // If there are no sections which require postprocessing, we can
2868 // handle the section names now, and avoid a resize later.
2869 if (!this->any_postprocessing_sections_)
2871 off = this->set_section_offsets(off,
2872 POSTPROCESSING_SECTIONS_PASS);
2874 this->set_section_offsets(off,
2875 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS);
2878 file_header->set_section_info(this->section_headers_, shstrtab_section);
2880 // Now we know exactly where everything goes in the output file
2881 // (except for non-allocated sections which require postprocessing).
2882 Output_data::layout_complete();
2884 this->output_file_size_ = off;
2889 // Create a note header following the format defined in the ELF ABI.
2890 // NAME is the name, NOTE_TYPE is the type, SECTION_NAME is the name
2891 // of the section to create, DESCSZ is the size of the descriptor.
2892 // ALLOCATE is true if the section should be allocated in memory.
2893 // This returns the new note section. It sets *TRAILING_PADDING to
2894 // the number of trailing zero bytes required.
2897 Layout::create_note(const char* name, int note_type,
2898 const char* section_name, size_t descsz,
2899 bool allocate, size_t* trailing_padding)
2901 // Authorities all agree that the values in a .note field should
2902 // be aligned on 4-byte boundaries for 32-bit binaries. However,
2903 // they differ on what the alignment is for 64-bit binaries.
2904 // The GABI says unambiguously they take 8-byte alignment:
2905 // http://sco.com/developers/gabi/latest/ch5.pheader.html#note_section
2906 // Other documentation says alignment should always be 4 bytes:
2907 // http://www.netbsd.org/docs/kernel/elf-notes.html#note-format
2908 // GNU ld and GNU readelf both support the latter (at least as of
2909 // version 2.16.91), and glibc always generates the latter for
2910 // .note.ABI-tag (as of version 1.6), so that's the one we go with
2912 #ifdef GABI_FORMAT_FOR_DOTNOTE_SECTION // This is not defined by default.
2913 const int size = parameters->target().get_size();
2915 const int size = 32;
2918 // The contents of the .note section.
2919 size_t namesz = strlen(name) + 1;
2920 size_t aligned_namesz = align_address(namesz, size / 8);
2921 size_t aligned_descsz = align_address(descsz, size / 8);
2923 size_t notehdrsz = 3 * (size / 8) + aligned_namesz;
2925 unsigned char* buffer = new unsigned char[notehdrsz];
2926 memset(buffer, 0, notehdrsz);
2928 bool is_big_endian = parameters->target().is_big_endian();
2934 elfcpp::Swap<32, false>::writeval(buffer, namesz);
2935 elfcpp::Swap<32, false>::writeval(buffer + 4, descsz);
2936 elfcpp::Swap<32, false>::writeval(buffer + 8, note_type);
2940 elfcpp::Swap<32, true>::writeval(buffer, namesz);
2941 elfcpp::Swap<32, true>::writeval(buffer + 4, descsz);
2942 elfcpp::Swap<32, true>::writeval(buffer + 8, note_type);
2945 else if (size == 64)
2949 elfcpp::Swap<64, false>::writeval(buffer, namesz);
2950 elfcpp::Swap<64, false>::writeval(buffer + 8, descsz);
2951 elfcpp::Swap<64, false>::writeval(buffer + 16, note_type);
2955 elfcpp::Swap<64, true>::writeval(buffer, namesz);
2956 elfcpp::Swap<64, true>::writeval(buffer + 8, descsz);
2957 elfcpp::Swap<64, true>::writeval(buffer + 16, note_type);
2963 memcpy(buffer + 3 * (size / 8), name, namesz);
2965 elfcpp::Elf_Xword flags = 0;
2966 Output_section_order order = ORDER_INVALID;
2969 flags = elfcpp::SHF_ALLOC;
2970 order = ORDER_RO_NOTE;
2972 Output_section* os = this->choose_output_section(NULL, section_name,
2974 flags, false, order, false,
2979 Output_section_data* posd = new Output_data_const_buffer(buffer, notehdrsz,
2982 os->add_output_section_data(posd);
2984 *trailing_padding = aligned_descsz - descsz;
2989 // For an executable or shared library, create a note to record the
2990 // version of gold used to create the binary.
2993 Layout::create_gold_note()
2995 if (parameters->options().relocatable()
2996 || parameters->incremental_update())
2999 std::string desc = std::string("gold ") + gold::get_version_string();
3001 size_t trailing_padding;
3002 Output_section* os = this->create_note("GNU", elfcpp::NT_GNU_GOLD_VERSION,
3003 ".note.gnu.gold-version", desc.size(),
3004 false, &trailing_padding);
3008 Output_section_data* posd = new Output_data_const(desc, 4);
3009 os->add_output_section_data(posd);
3011 if (trailing_padding > 0)
3013 posd = new Output_data_zero_fill(trailing_padding, 0);
3014 os->add_output_section_data(posd);
3018 // Record whether the stack should be executable. This can be set
3019 // from the command line using the -z execstack or -z noexecstack
3020 // options. Otherwise, if any input file has a .note.GNU-stack
3021 // section with the SHF_EXECINSTR flag set, the stack should be
3022 // executable. Otherwise, if at least one input file a
3023 // .note.GNU-stack section, and some input file has no .note.GNU-stack
3024 // section, we use the target default for whether the stack should be
3025 // executable. If -z stack-size was used to set a p_memsz value for
3026 // PT_GNU_STACK, we generate the segment regardless. Otherwise, we
3027 // don't generate a stack note. When generating a object file, we
3028 // create a .note.GNU-stack section with the appropriate marking.
3029 // When generating an executable or shared library, we create a
3030 // PT_GNU_STACK segment.
3033 Layout::create_stack_segment()
3035 bool is_stack_executable;
3036 if (parameters->options().is_execstack_set())
3038 is_stack_executable = parameters->options().is_stack_executable();
3039 if (!is_stack_executable
3040 && this->input_requires_executable_stack_
3041 && parameters->options().warn_execstack())
3042 gold_warning(_("one or more inputs require executable stack, "
3043 "but -z noexecstack was given"));
3045 else if (!this->input_with_gnu_stack_note_
3046 && (!parameters->options().user_set_stack_size()
3047 || parameters->options().relocatable()))
3051 if (this->input_requires_executable_stack_)
3052 is_stack_executable = true;
3053 else if (this->input_without_gnu_stack_note_)
3054 is_stack_executable =
3055 parameters->target().is_default_stack_executable();
3057 is_stack_executable = false;
3060 if (parameters->options().relocatable())
3062 const char* name = this->namepool_.add(".note.GNU-stack", false, NULL);
3063 elfcpp::Elf_Xword flags = 0;
3064 if (is_stack_executable)
3065 flags |= elfcpp::SHF_EXECINSTR;
3066 this->make_output_section(name, elfcpp::SHT_PROGBITS, flags,
3067 ORDER_INVALID, false);
3071 if (this->script_options_->saw_phdrs_clause())
3073 int flags = elfcpp::PF_R | elfcpp::PF_W;
3074 if (is_stack_executable)
3075 flags |= elfcpp::PF_X;
3076 Output_segment* seg =
3077 this->make_output_segment(elfcpp::PT_GNU_STACK, flags);
3078 seg->set_size(parameters->options().stack_size());
3079 // BFD lets targets override this default alignment, but the only
3080 // targets that do so are ones that Gold does not support so far.
3081 seg->set_minimum_p_align(16);
3085 // If --build-id was used, set up the build ID note.
3088 Layout::create_build_id()
3090 if (!parameters->options().user_set_build_id())
3093 const char* style = parameters->options().build_id();
3094 if (strcmp(style, "none") == 0)
3097 // Set DESCSZ to the size of the note descriptor. When possible,
3098 // set DESC to the note descriptor contents.
3101 if (strcmp(style, "md5") == 0)
3103 else if ((strcmp(style, "sha1") == 0) || (strcmp(style, "tree") == 0))
3105 else if (strcmp(style, "uuid") == 0)
3108 const size_t uuidsz = 128 / 8;
3110 char buffer[uuidsz];
3111 memset(buffer, 0, uuidsz);
3113 int descriptor = open_descriptor(-1, "/dev/urandom", O_RDONLY);
3115 gold_error(_("--build-id=uuid failed: could not open /dev/urandom: %s"),
3119 ssize_t got = ::read(descriptor, buffer, uuidsz);
3120 release_descriptor(descriptor, true);
3122 gold_error(_("/dev/urandom: read failed: %s"), strerror(errno));
3123 else if (static_cast<size_t>(got) != uuidsz)
3124 gold_error(_("/dev/urandom: expected %zu bytes, got %zd bytes"),
3128 desc.assign(buffer, uuidsz);
3130 #else // __MINGW32__
3132 typedef RPC_STATUS (RPC_ENTRY *UuidCreateFn)(UUID *Uuid);
3134 HMODULE rpc_library = LoadLibrary("rpcrt4.dll");
3136 gold_error(_("--build-id=uuid failed: could not load rpcrt4.dll"));
3139 UuidCreateFn uuid_create = reinterpret_cast<UuidCreateFn>(
3140 GetProcAddress(rpc_library, "UuidCreate"));
3142 gold_error(_("--build-id=uuid failed: could not find UuidCreate"));
3143 else if (uuid_create(&uuid) != RPC_S_OK)
3144 gold_error(_("__build_id=uuid failed: call UuidCreate() failed"));
3145 FreeLibrary(rpc_library);
3147 desc.assign(reinterpret_cast<const char *>(&uuid), sizeof(UUID));
3148 descsz = sizeof(UUID);
3149 #endif // __MINGW32__
3151 else if (strncmp(style, "0x", 2) == 0)
3154 const char* p = style + 2;
3157 if (hex_p(p[0]) && hex_p(p[1]))
3159 char c = (hex_value(p[0]) << 4) | hex_value(p[1]);
3163 else if (*p == '-' || *p == ':')
3166 gold_fatal(_("--build-id argument '%s' not a valid hex number"),
3169 descsz = desc.size();
3172 gold_fatal(_("unrecognized --build-id argument '%s'"), style);
3175 size_t trailing_padding;
3176 Output_section* os = this->create_note("GNU", elfcpp::NT_GNU_BUILD_ID,
3177 ".note.gnu.build-id", descsz, true,
3184 // We know the value already, so we fill it in now.
3185 gold_assert(desc.size() == descsz);
3187 Output_section_data* posd = new Output_data_const(desc, 4);
3188 os->add_output_section_data(posd);
3190 if (trailing_padding != 0)
3192 posd = new Output_data_zero_fill(trailing_padding, 0);
3193 os->add_output_section_data(posd);
3198 // We need to compute a checksum after we have completed the
3200 gold_assert(trailing_padding == 0);
3201 this->build_id_note_ = new Output_data_zero_fill(descsz, 4);
3202 os->add_output_section_data(this->build_id_note_);
3206 // If we have both .stabXX and .stabXXstr sections, then the sh_link
3207 // field of the former should point to the latter. I'm not sure who
3208 // started this, but the GNU linker does it, and some tools depend
3212 Layout::link_stabs_sections()
3214 if (!this->have_stabstr_section_)
3217 for (Section_list::iterator p = this->section_list_.begin();
3218 p != this->section_list_.end();
3221 if ((*p)->type() != elfcpp::SHT_STRTAB)
3224 const char* name = (*p)->name();
3225 if (strncmp(name, ".stab", 5) != 0)
3228 size_t len = strlen(name);
3229 if (strcmp(name + len - 3, "str") != 0)
3232 std::string stab_name(name, len - 3);
3233 Output_section* stab_sec;
3234 stab_sec = this->find_output_section(stab_name.c_str());
3235 if (stab_sec != NULL)
3236 stab_sec->set_link_section(*p);
3240 // Create .gnu_incremental_inputs and related sections needed
3241 // for the next run of incremental linking to check what has changed.
3244 Layout::create_incremental_info_sections(Symbol_table* symtab)
3246 Incremental_inputs* incr = this->incremental_inputs_;
3248 gold_assert(incr != NULL);
3250 // Create the .gnu_incremental_inputs, _symtab, and _relocs input sections.
3251 incr->create_data_sections(symtab);
3253 // Add the .gnu_incremental_inputs section.
3254 const char* incremental_inputs_name =
3255 this->namepool_.add(".gnu_incremental_inputs", false, NULL);
3256 Output_section* incremental_inputs_os =
3257 this->make_output_section(incremental_inputs_name,
3258 elfcpp::SHT_GNU_INCREMENTAL_INPUTS, 0,
3259 ORDER_INVALID, false);
3260 incremental_inputs_os->add_output_section_data(incr->inputs_section());
3262 // Add the .gnu_incremental_symtab section.
3263 const char* incremental_symtab_name =
3264 this->namepool_.add(".gnu_incremental_symtab", false, NULL);
3265 Output_section* incremental_symtab_os =
3266 this->make_output_section(incremental_symtab_name,
3267 elfcpp::SHT_GNU_INCREMENTAL_SYMTAB, 0,
3268 ORDER_INVALID, false);
3269 incremental_symtab_os->add_output_section_data(incr->symtab_section());
3270 incremental_symtab_os->set_entsize(4);
3272 // Add the .gnu_incremental_relocs section.
3273 const char* incremental_relocs_name =
3274 this->namepool_.add(".gnu_incremental_relocs", false, NULL);
3275 Output_section* incremental_relocs_os =
3276 this->make_output_section(incremental_relocs_name,
3277 elfcpp::SHT_GNU_INCREMENTAL_RELOCS, 0,
3278 ORDER_INVALID, false);
3279 incremental_relocs_os->add_output_section_data(incr->relocs_section());
3280 incremental_relocs_os->set_entsize(incr->relocs_entsize());
3282 // Add the .gnu_incremental_got_plt section.
3283 const char* incremental_got_plt_name =
3284 this->namepool_.add(".gnu_incremental_got_plt", false, NULL);
3285 Output_section* incremental_got_plt_os =
3286 this->make_output_section(incremental_got_plt_name,
3287 elfcpp::SHT_GNU_INCREMENTAL_GOT_PLT, 0,
3288 ORDER_INVALID, false);
3289 incremental_got_plt_os->add_output_section_data(incr->got_plt_section());
3291 // Add the .gnu_incremental_strtab section.
3292 const char* incremental_strtab_name =
3293 this->namepool_.add(".gnu_incremental_strtab", false, NULL);
3294 Output_section* incremental_strtab_os = this->make_output_section(incremental_strtab_name,
3295 elfcpp::SHT_STRTAB, 0,
3296 ORDER_INVALID, false);
3297 Output_data_strtab* strtab_data =
3298 new Output_data_strtab(incr->get_stringpool());
3299 incremental_strtab_os->add_output_section_data(strtab_data);
3301 incremental_inputs_os->set_after_input_sections();
3302 incremental_symtab_os->set_after_input_sections();
3303 incremental_relocs_os->set_after_input_sections();
3304 incremental_got_plt_os->set_after_input_sections();
3306 incremental_inputs_os->set_link_section(incremental_strtab_os);
3307 incremental_symtab_os->set_link_section(incremental_inputs_os);
3308 incremental_relocs_os->set_link_section(incremental_inputs_os);
3309 incremental_got_plt_os->set_link_section(incremental_inputs_os);
3312 // Return whether SEG1 should be before SEG2 in the output file. This
3313 // is based entirely on the segment type and flags. When this is
3314 // called the segment addresses have normally not yet been set.
3317 Layout::segment_precedes(const Output_segment* seg1,
3318 const Output_segment* seg2)
3320 // In order to produce a stable ordering if we're called with the same pointer
3325 elfcpp::Elf_Word type1 = seg1->type();
3326 elfcpp::Elf_Word type2 = seg2->type();
3328 // The single PT_PHDR segment is required to precede any loadable
3329 // segment. We simply make it always first.
3330 if (type1 == elfcpp::PT_PHDR)
3332 gold_assert(type2 != elfcpp::PT_PHDR);
3335 if (type2 == elfcpp::PT_PHDR)
3338 // The single PT_INTERP segment is required to precede any loadable
3339 // segment. We simply make it always second.
3340 if (type1 == elfcpp::PT_INTERP)
3342 gold_assert(type2 != elfcpp::PT_INTERP);
3345 if (type2 == elfcpp::PT_INTERP)
3348 // We then put PT_LOAD segments before any other segments.
3349 if (type1 == elfcpp::PT_LOAD && type2 != elfcpp::PT_LOAD)
3351 if (type2 == elfcpp::PT_LOAD && type1 != elfcpp::PT_LOAD)
3354 // We put the PT_TLS segment last except for the PT_GNU_RELRO
3355 // segment, because that is where the dynamic linker expects to find
3356 // it (this is just for efficiency; other positions would also work
3358 if (type1 == elfcpp::PT_TLS
3359 && type2 != elfcpp::PT_TLS
3360 && type2 != elfcpp::PT_GNU_RELRO)
3362 if (type2 == elfcpp::PT_TLS
3363 && type1 != elfcpp::PT_TLS
3364 && type1 != elfcpp::PT_GNU_RELRO)
3367 // We put the PT_GNU_RELRO segment last, because that is where the
3368 // dynamic linker expects to find it (as with PT_TLS, this is just
3370 if (type1 == elfcpp::PT_GNU_RELRO && type2 != elfcpp::PT_GNU_RELRO)
3372 if (type2 == elfcpp::PT_GNU_RELRO && type1 != elfcpp::PT_GNU_RELRO)
3375 const elfcpp::Elf_Word flags1 = seg1->flags();
3376 const elfcpp::Elf_Word flags2 = seg2->flags();
3378 // The order of non-PT_LOAD segments is unimportant. We simply sort
3379 // by the numeric segment type and flags values. There should not
3380 // be more than one segment with the same type and flags, except
3381 // when a linker script specifies such.
3382 if (type1 != elfcpp::PT_LOAD)
3385 return type1 < type2;
3386 gold_assert(flags1 != flags2
3387 || this->script_options_->saw_phdrs_clause());
3388 return flags1 < flags2;
3391 // If the addresses are set already, sort by load address.
3392 if (seg1->are_addresses_set())
3394 if (!seg2->are_addresses_set())
3397 unsigned int section_count1 = seg1->output_section_count();
3398 unsigned int section_count2 = seg2->output_section_count();
3399 if (section_count1 == 0 && section_count2 > 0)
3401 if (section_count1 > 0 && section_count2 == 0)
3404 uint64_t paddr1 = (seg1->are_addresses_set()
3406 : seg1->first_section_load_address());
3407 uint64_t paddr2 = (seg2->are_addresses_set()
3409 : seg2->first_section_load_address());
3411 if (paddr1 != paddr2)
3412 return paddr1 < paddr2;
3414 else if (seg2->are_addresses_set())
3417 // A segment which holds large data comes after a segment which does
3418 // not hold large data.
3419 if (seg1->is_large_data_segment())
3421 if (!seg2->is_large_data_segment())
3424 else if (seg2->is_large_data_segment())
3427 // Otherwise, we sort PT_LOAD segments based on the flags. Readonly
3428 // segments come before writable segments. Then writable segments
3429 // with data come before writable segments without data. Then
3430 // executable segments come before non-executable segments. Then
3431 // the unlikely case of a non-readable segment comes before the
3432 // normal case of a readable segment. If there are multiple
3433 // segments with the same type and flags, we require that the
3434 // address be set, and we sort by virtual address and then physical
3436 if ((flags1 & elfcpp::PF_W) != (flags2 & elfcpp::PF_W))
3437 return (flags1 & elfcpp::PF_W) == 0;
3438 if ((flags1 & elfcpp::PF_W) != 0
3439 && seg1->has_any_data_sections() != seg2->has_any_data_sections())
3440 return seg1->has_any_data_sections();
3441 if ((flags1 & elfcpp::PF_X) != (flags2 & elfcpp::PF_X))
3442 return (flags1 & elfcpp::PF_X) != 0;
3443 if ((flags1 & elfcpp::PF_R) != (flags2 & elfcpp::PF_R))
3444 return (flags1 & elfcpp::PF_R) == 0;
3446 // We shouldn't get here--we shouldn't create segments which we
3447 // can't distinguish. Unless of course we are using a weird linker
3448 // script or overlapping --section-start options. We could also get
3449 // here if plugins want unique segments for subsets of sections.
3450 gold_assert(this->script_options_->saw_phdrs_clause()
3451 || parameters->options().any_section_start()
3452 || this->is_unique_segment_for_sections_specified());
3456 // Increase OFF so that it is congruent to ADDR modulo ABI_PAGESIZE.
3459 align_file_offset(off_t off, uint64_t addr, uint64_t abi_pagesize)
3461 uint64_t unsigned_off = off;
3462 uint64_t aligned_off = ((unsigned_off & ~(abi_pagesize - 1))
3463 | (addr & (abi_pagesize - 1)));
3464 if (aligned_off < unsigned_off)
3465 aligned_off += abi_pagesize;
3469 // On targets where the text segment contains only executable code,
3470 // a non-executable segment is never the text segment.
3473 is_text_segment(const Target* target, const Output_segment* seg)
3475 elfcpp::Elf_Xword flags = seg->flags();
3476 if ((flags & elfcpp::PF_W) != 0)
3478 if ((flags & elfcpp::PF_X) == 0)
3479 return !target->isolate_execinstr();
3483 // Set the file offsets of all the segments, and all the sections they
3484 // contain. They have all been created. LOAD_SEG must be laid out
3485 // first. Return the offset of the data to follow.
3488 Layout::set_segment_offsets(const Target* target, Output_segment* load_seg,
3489 unsigned int* pshndx)
3491 // Sort them into the final order. We use a stable sort so that we
3492 // don't randomize the order of indistinguishable segments created
3493 // by linker scripts.
3494 std::stable_sort(this->segment_list_.begin(), this->segment_list_.end(),
3495 Layout::Compare_segments(this));
3497 // Find the PT_LOAD segments, and set their addresses and offsets
3498 // and their section's addresses and offsets.
3499 uint64_t start_addr;
3500 if (parameters->options().user_set_Ttext())
3501 start_addr = parameters->options().Ttext();
3502 else if (parameters->options().output_is_position_independent())
3505 start_addr = target->default_text_segment_address();
3507 uint64_t addr = start_addr;
3510 // If LOAD_SEG is NULL, then the file header and segment headers
3511 // will not be loadable. But they still need to be at offset 0 in
3512 // the file. Set their offsets now.
3513 if (load_seg == NULL)
3515 for (Data_list::iterator p = this->special_output_list_.begin();
3516 p != this->special_output_list_.end();
3519 off = align_address(off, (*p)->addralign());
3520 (*p)->set_address_and_file_offset(0, off);
3521 off += (*p)->data_size();
3525 unsigned int increase_relro = this->increase_relro_;
3526 if (this->script_options_->saw_sections_clause())
3529 const bool check_sections = parameters->options().check_sections();
3530 Output_segment* last_load_segment = NULL;
3532 unsigned int shndx_begin = *pshndx;
3533 unsigned int shndx_load_seg = *pshndx;
3535 for (Segment_list::iterator p = this->segment_list_.begin();
3536 p != this->segment_list_.end();
3539 if ((*p)->type() == elfcpp::PT_LOAD)
3541 if (target->isolate_execinstr())
3543 // When we hit the segment that should contain the
3544 // file headers, reset the file offset so we place
3545 // it and subsequent segments appropriately.
3546 // We'll fix up the preceding segments below.
3554 shndx_load_seg = *pshndx;
3560 // Verify that the file headers fall into the first segment.
3561 if (load_seg != NULL && load_seg != *p)
3566 bool are_addresses_set = (*p)->are_addresses_set();
3567 if (are_addresses_set)
3569 // When it comes to setting file offsets, we care about
3570 // the physical address.
3571 addr = (*p)->paddr();
3573 else if (parameters->options().user_set_Ttext()
3574 && (parameters->options().omagic()
3575 || is_text_segment(target, *p)))
3577 are_addresses_set = true;
3579 else if (parameters->options().user_set_Trodata_segment()
3580 && ((*p)->flags() & (elfcpp::PF_W | elfcpp::PF_X)) == 0)
3582 addr = parameters->options().Trodata_segment();
3583 are_addresses_set = true;
3585 else if (parameters->options().user_set_Tdata()
3586 && ((*p)->flags() & elfcpp::PF_W) != 0
3587 && (!parameters->options().user_set_Tbss()
3588 || (*p)->has_any_data_sections()))
3590 addr = parameters->options().Tdata();
3591 are_addresses_set = true;
3593 else if (parameters->options().user_set_Tbss()
3594 && ((*p)->flags() & elfcpp::PF_W) != 0
3595 && !(*p)->has_any_data_sections())
3597 addr = parameters->options().Tbss();
3598 are_addresses_set = true;
3601 uint64_t orig_addr = addr;
3602 uint64_t orig_off = off;
3604 uint64_t aligned_addr = 0;
3605 uint64_t abi_pagesize = target->abi_pagesize();
3606 uint64_t common_pagesize = target->common_pagesize();
3608 if (!parameters->options().nmagic()
3609 && !parameters->options().omagic())
3610 (*p)->set_minimum_p_align(abi_pagesize);
3612 if (!are_addresses_set)
3614 // Skip the address forward one page, maintaining the same
3615 // position within the page. This lets us store both segments
3616 // overlapping on a single page in the file, but the loader will
3617 // put them on different pages in memory. We will revisit this
3618 // decision once we know the size of the segment.
3620 uint64_t max_align = (*p)->maximum_alignment();
3621 if (max_align > abi_pagesize)
3622 addr = align_address(addr, max_align);
3623 aligned_addr = addr;
3627 // This is the segment that will contain the file
3628 // headers, so its offset will have to be exactly zero.
3629 gold_assert(orig_off == 0);
3631 // If the target wants a fixed minimum distance from the
3632 // text segment to the read-only segment, move up now.
3634 start_addr + (parameters->options().user_set_rosegment_gap()
3635 ? parameters->options().rosegment_gap()
3636 : target->rosegment_gap());
3637 if (addr < min_addr)
3640 // But this is not the first segment! To make its
3641 // address congruent with its offset, that address better
3642 // be aligned to the ABI-mandated page size.
3643 addr = align_address(addr, abi_pagesize);
3644 aligned_addr = addr;
3648 if ((addr & (abi_pagesize - 1)) != 0)
3649 addr = addr + abi_pagesize;
3651 off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
3655 if (!parameters->options().nmagic()
3656 && !parameters->options().omagic())
3658 // Here we are also taking care of the case when
3659 // the maximum segment alignment is larger than the page size.
3660 off = align_file_offset(off, addr,
3661 std::max(abi_pagesize,
3662 (*p)->maximum_alignment()));
3666 // This is -N or -n with a section script which prevents
3667 // us from using a load segment. We need to ensure that
3668 // the file offset is aligned to the alignment of the
3669 // segment. This is because the linker script
3670 // implicitly assumed a zero offset. If we don't align
3671 // here, then the alignment of the sections in the
3672 // linker script may not match the alignment of the
3673 // sections in the set_section_addresses call below,
3674 // causing an error about dot moving backward.
3675 off = align_address(off, (*p)->maximum_alignment());
3678 unsigned int shndx_hold = *pshndx;
3679 bool has_relro = false;
3680 uint64_t new_addr = (*p)->set_section_addresses(target, this,
3686 // Now that we know the size of this segment, we may be able
3687 // to save a page in memory, at the cost of wasting some
3688 // file space, by instead aligning to the start of a new
3689 // page. Here we use the real machine page size rather than
3690 // the ABI mandated page size. If the segment has been
3691 // aligned so that the relro data ends at a page boundary,
3692 // we do not try to realign it.
3694 if (!are_addresses_set
3696 && aligned_addr != addr
3697 && !parameters->incremental())
3699 uint64_t first_off = (common_pagesize
3701 & (common_pagesize - 1)));
3702 uint64_t last_off = new_addr & (common_pagesize - 1);
3705 && ((aligned_addr & ~ (common_pagesize - 1))
3706 != (new_addr & ~ (common_pagesize - 1)))
3707 && first_off + last_off <= common_pagesize)
3709 *pshndx = shndx_hold;
3710 addr = align_address(aligned_addr, common_pagesize);
3711 addr = align_address(addr, (*p)->maximum_alignment());
3712 if ((addr & (abi_pagesize - 1)) != 0)
3713 addr = addr + abi_pagesize;
3714 off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
3715 off = align_file_offset(off, addr, abi_pagesize);
3717 increase_relro = this->increase_relro_;
3718 if (this->script_options_->saw_sections_clause())
3722 new_addr = (*p)->set_section_addresses(target, this,
3732 // Implement --check-sections. We know that the segments
3733 // are sorted by LMA.
3734 if (check_sections && last_load_segment != NULL)
3736 gold_assert(last_load_segment->paddr() <= (*p)->paddr());
3737 if (last_load_segment->paddr() + last_load_segment->memsz()
3740 unsigned long long lb1 = last_load_segment->paddr();
3741 unsigned long long le1 = lb1 + last_load_segment->memsz();
3742 unsigned long long lb2 = (*p)->paddr();
3743 unsigned long long le2 = lb2 + (*p)->memsz();
3744 gold_error(_("load segment overlap [0x%llx -> 0x%llx] and "
3745 "[0x%llx -> 0x%llx]"),
3746 lb1, le1, lb2, le2);
3749 last_load_segment = *p;
3753 if (load_seg != NULL && target->isolate_execinstr())
3755 // Process the early segments again, setting their file offsets
3756 // so they land after the segments starting at LOAD_SEG.
3757 off = align_file_offset(off, 0, target->abi_pagesize());
3759 this->reset_relax_output();
3761 for (Segment_list::iterator p = this->segment_list_.begin();
3765 if ((*p)->type() == elfcpp::PT_LOAD)
3767 // We repeat the whole job of assigning addresses and
3768 // offsets, but we really only want to change the offsets and
3769 // must ensure that the addresses all come out the same as
3770 // they did the first time through.
3771 bool has_relro = false;
3772 const uint64_t old_addr = (*p)->vaddr();
3773 const uint64_t old_end = old_addr + (*p)->memsz();
3774 uint64_t new_addr = (*p)->set_section_addresses(target, this,
3780 gold_assert(new_addr == old_end);
3784 gold_assert(shndx_begin == shndx_load_seg);
3787 // Handle the non-PT_LOAD segments, setting their offsets from their
3788 // section's offsets.
3789 for (Segment_list::iterator p = this->segment_list_.begin();
3790 p != this->segment_list_.end();
3793 // PT_GNU_STACK was set up correctly when it was created.
3794 if ((*p)->type() != elfcpp::PT_LOAD
3795 && (*p)->type() != elfcpp::PT_GNU_STACK)
3796 (*p)->set_offset((*p)->type() == elfcpp::PT_GNU_RELRO
3801 // Set the TLS offsets for each section in the PT_TLS segment.
3802 if (this->tls_segment_ != NULL)
3803 this->tls_segment_->set_tls_offsets();
3808 // Set the offsets of all the allocated sections when doing a
3809 // relocatable link. This does the same jobs as set_segment_offsets,
3810 // only for a relocatable link.
3813 Layout::set_relocatable_section_offsets(Output_data* file_header,
3814 unsigned int* pshndx)
3818 file_header->set_address_and_file_offset(0, 0);
3819 off += file_header->data_size();
3821 for (Section_list::iterator p = this->section_list_.begin();
3822 p != this->section_list_.end();
3825 // We skip unallocated sections here, except that group sections
3826 // have to come first.
3827 if (((*p)->flags() & elfcpp::SHF_ALLOC) == 0
3828 && (*p)->type() != elfcpp::SHT_GROUP)
3831 off = align_address(off, (*p)->addralign());
3833 // The linker script might have set the address.
3834 if (!(*p)->is_address_valid())
3835 (*p)->set_address(0);
3836 (*p)->set_file_offset(off);
3837 (*p)->finalize_data_size();
3838 if ((*p)->type() != elfcpp::SHT_NOBITS)
3839 off += (*p)->data_size();
3841 (*p)->set_out_shndx(*pshndx);
3848 // Set the file offset of all the sections not associated with a
3852 Layout::set_section_offsets(off_t off, Layout::Section_offset_pass pass)
3854 off_t startoff = off;
3857 for (Section_list::iterator p = this->unattached_section_list_.begin();
3858 p != this->unattached_section_list_.end();
3861 // The symtab section is handled in create_symtab_sections.
3862 if (*p == this->symtab_section_)
3865 // If we've already set the data size, don't set it again.
3866 if ((*p)->is_offset_valid() && (*p)->is_data_size_valid())
3869 if (pass == BEFORE_INPUT_SECTIONS_PASS
3870 && (*p)->requires_postprocessing())
3872 (*p)->create_postprocessing_buffer();
3873 this->any_postprocessing_sections_ = true;
3876 if (pass == BEFORE_INPUT_SECTIONS_PASS
3877 && (*p)->after_input_sections())
3879 else if (pass == POSTPROCESSING_SECTIONS_PASS
3880 && (!(*p)->after_input_sections()
3881 || (*p)->type() == elfcpp::SHT_STRTAB))
3883 else if (pass == STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
3884 && (!(*p)->after_input_sections()
3885 || (*p)->type() != elfcpp::SHT_STRTAB))
3888 if (!parameters->incremental_update())
3890 off = align_address(off, (*p)->addralign());
3891 (*p)->set_file_offset(off);
3892 (*p)->finalize_data_size();
3896 // Incremental update: allocate file space from free list.
3897 (*p)->pre_finalize_data_size();
3898 off_t current_size = (*p)->current_data_size();
3899 off = this->allocate(current_size, (*p)->addralign(), startoff);
3902 if (is_debugging_enabled(DEBUG_INCREMENTAL))
3903 this->free_list_.dump();
3904 gold_assert((*p)->output_section() != NULL);
3905 gold_fallback(_("out of patch space for section %s; "
3906 "relink with --incremental-full"),
3907 (*p)->output_section()->name());
3909 (*p)->set_file_offset(off);
3910 (*p)->finalize_data_size();
3911 if ((*p)->data_size() > current_size)
3913 gold_assert((*p)->output_section() != NULL);
3914 gold_fallback(_("%s: section changed size; "
3915 "relink with --incremental-full"),
3916 (*p)->output_section()->name());
3918 gold_debug(DEBUG_INCREMENTAL,
3919 "set_section_offsets: %08lx %08lx %s",
3920 static_cast<long>(off),
3921 static_cast<long>((*p)->data_size()),
3922 ((*p)->output_section() != NULL
3923 ? (*p)->output_section()->name() : "(special)"));
3926 off += (*p)->data_size();
3930 // At this point the name must be set.
3931 if (pass != STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS)
3932 this->namepool_.add((*p)->name(), false, NULL);
3937 // Set the section indexes of all the sections not associated with a
3941 Layout::set_section_indexes(unsigned int shndx)
3943 for (Section_list::iterator p = this->unattached_section_list_.begin();
3944 p != this->unattached_section_list_.end();
3947 if (!(*p)->has_out_shndx())
3949 (*p)->set_out_shndx(shndx);
3956 // Set the section addresses according to the linker script. This is
3957 // only called when we see a SECTIONS clause. This returns the
3958 // program segment which should hold the file header and segment
3959 // headers, if any. It will return NULL if they should not be in a
3963 Layout::set_section_addresses_from_script(Symbol_table* symtab)
3965 Script_sections* ss = this->script_options_->script_sections();
3966 gold_assert(ss->saw_sections_clause());
3967 return this->script_options_->set_section_addresses(symtab, this);
3970 // Place the orphan sections in the linker script.
3973 Layout::place_orphan_sections_in_script()
3975 Script_sections* ss = this->script_options_->script_sections();
3976 gold_assert(ss->saw_sections_clause());
3978 // Place each orphaned output section in the script.
3979 for (Section_list::iterator p = this->section_list_.begin();
3980 p != this->section_list_.end();
3983 if (!(*p)->found_in_sections_clause())
3984 ss->place_orphan(*p);
3988 // Count the local symbols in the regular symbol table and the dynamic
3989 // symbol table, and build the respective string pools.
3992 Layout::count_local_symbols(const Task* task,
3993 const Input_objects* input_objects)
3995 // First, figure out an upper bound on the number of symbols we'll
3996 // be inserting into each pool. This helps us create the pools with
3997 // the right size, to avoid unnecessary hashtable resizing.
3998 unsigned int symbol_count = 0;
3999 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
4000 p != input_objects->relobj_end();
4002 symbol_count += (*p)->local_symbol_count();
4004 // Go from "upper bound" to "estimate." We overcount for two
4005 // reasons: we double-count symbols that occur in more than one
4006 // object file, and we count symbols that are dropped from the
4007 // output. Add it all together and assume we overcount by 100%.
4010 // We assume all symbols will go into both the sympool and dynpool.
4011 this->sympool_.reserve(symbol_count);
4012 this->dynpool_.reserve(symbol_count);
4014 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
4015 p != input_objects->relobj_end();
4018 Task_lock_obj<Object> tlo(task, *p);
4019 (*p)->count_local_symbols(&this->sympool_, &this->dynpool_);
4023 // Create the symbol table sections. Here we also set the final
4024 // values of the symbols. At this point all the loadable sections are
4025 // fully laid out. SHNUM is the number of sections so far.
4028 Layout::create_symtab_sections(const Input_objects* input_objects,
4029 Symbol_table* symtab,
4032 unsigned int local_dynamic_count)
4036 if (parameters->target().get_size() == 32)
4038 symsize = elfcpp::Elf_sizes<32>::sym_size;
4041 else if (parameters->target().get_size() == 64)
4043 symsize = elfcpp::Elf_sizes<64>::sym_size;
4049 // Compute file offsets relative to the start of the symtab section.
4052 // Save space for the dummy symbol at the start of the section. We
4053 // never bother to write this out--it will just be left as zero.
4055 unsigned int local_symbol_index = 1;
4057 // Add STT_SECTION symbols for each Output section which needs one.
4058 for (Section_list::iterator p = this->section_list_.begin();
4059 p != this->section_list_.end();
4062 if (!(*p)->needs_symtab_index())
4063 (*p)->set_symtab_index(-1U);
4066 (*p)->set_symtab_index(local_symbol_index);
4067 ++local_symbol_index;
4072 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
4073 p != input_objects->relobj_end();
4076 unsigned int index = (*p)->finalize_local_symbols(local_symbol_index,
4078 off += (index - local_symbol_index) * symsize;
4079 local_symbol_index = index;
4082 unsigned int local_symcount = local_symbol_index;
4083 gold_assert(static_cast<off_t>(local_symcount * symsize) == off);
4087 if (this->dynsym_section_ == NULL)
4094 off_t locsize = local_dynamic_count * this->dynsym_section_->entsize();
4095 dynoff = this->dynsym_section_->offset() + locsize;
4096 dyncount = (this->dynsym_section_->data_size() - locsize) / symsize;
4097 gold_assert(static_cast<off_t>(dyncount * symsize)
4098 == this->dynsym_section_->data_size() - locsize);
4101 off_t global_off = off;
4102 off = symtab->finalize(off, dynoff, local_dynamic_count, dyncount,
4103 &this->sympool_, &local_symcount);
4105 if (!parameters->options().strip_all())
4107 this->sympool_.set_string_offsets();
4109 const char* symtab_name = this->namepool_.add(".symtab", false, NULL);
4110 Output_section* osymtab = this->make_output_section(symtab_name,
4114 this->symtab_section_ = osymtab;
4116 Output_section_data* pos = new Output_data_fixed_space(off, align,
4118 osymtab->add_output_section_data(pos);
4120 // We generate a .symtab_shndx section if we have more than
4121 // SHN_LORESERVE sections. Technically it is possible that we
4122 // don't need one, because it is possible that there are no
4123 // symbols in any of sections with indexes larger than
4124 // SHN_LORESERVE. That is probably unusual, though, and it is
4125 // easier to always create one than to compute section indexes
4126 // twice (once here, once when writing out the symbols).
4127 if (shnum >= elfcpp::SHN_LORESERVE)
4129 const char* symtab_xindex_name = this->namepool_.add(".symtab_shndx",
4131 Output_section* osymtab_xindex =
4132 this->make_output_section(symtab_xindex_name,
4133 elfcpp::SHT_SYMTAB_SHNDX, 0,
4134 ORDER_INVALID, false);
4136 size_t symcount = off / symsize;
4137 this->symtab_xindex_ = new Output_symtab_xindex(symcount);
4139 osymtab_xindex->add_output_section_data(this->symtab_xindex_);
4141 osymtab_xindex->set_link_section(osymtab);
4142 osymtab_xindex->set_addralign(4);
4143 osymtab_xindex->set_entsize(4);
4145 osymtab_xindex->set_after_input_sections();
4147 // This tells the driver code to wait until the symbol table
4148 // has written out before writing out the postprocessing
4149 // sections, including the .symtab_shndx section.
4150 this->any_postprocessing_sections_ = true;
4153 const char* strtab_name = this->namepool_.add(".strtab", false, NULL);
4154 Output_section* ostrtab = this->make_output_section(strtab_name,
4159 Output_section_data* pstr = new Output_data_strtab(&this->sympool_);
4160 ostrtab->add_output_section_data(pstr);
4163 if (!parameters->incremental_update())
4164 symtab_off = align_address(*poff, align);
4167 symtab_off = this->allocate(off, align, *poff);
4169 gold_fallback(_("out of patch space for symbol table; "
4170 "relink with --incremental-full"));
4171 gold_debug(DEBUG_INCREMENTAL,
4172 "create_symtab_sections: %08lx %08lx .symtab",
4173 static_cast<long>(symtab_off),
4174 static_cast<long>(off));
4177 symtab->set_file_offset(symtab_off + global_off);
4178 osymtab->set_file_offset(symtab_off);
4179 osymtab->finalize_data_size();
4180 osymtab->set_link_section(ostrtab);
4181 osymtab->set_info(local_symcount);
4182 osymtab->set_entsize(symsize);
4184 if (symtab_off + off > *poff)
4185 *poff = symtab_off + off;
4189 // Create the .shstrtab section, which holds the names of the
4190 // sections. At the time this is called, we have created all the
4191 // output sections except .shstrtab itself.
4194 Layout::create_shstrtab()
4196 // FIXME: We don't need to create a .shstrtab section if we are
4197 // stripping everything.
4199 const char* name = this->namepool_.add(".shstrtab", false, NULL);
4201 Output_section* os = this->make_output_section(name, elfcpp::SHT_STRTAB, 0,
4202 ORDER_INVALID, false);
4204 if (strcmp(parameters->options().compress_debug_sections(), "none") != 0)
4206 // We can't write out this section until we've set all the
4207 // section names, and we don't set the names of compressed
4208 // output sections until relocations are complete. FIXME: With
4209 // the current names we use, this is unnecessary.
4210 os->set_after_input_sections();
4213 Output_section_data* posd = new Output_data_strtab(&this->namepool_);
4214 os->add_output_section_data(posd);
4219 // Create the section headers. SIZE is 32 or 64. OFF is the file
4223 Layout::create_shdrs(const Output_section* shstrtab_section, off_t* poff)
4225 Output_section_headers* oshdrs;
4226 oshdrs = new Output_section_headers(this,
4227 &this->segment_list_,
4228 &this->section_list_,
4229 &this->unattached_section_list_,
4233 if (!parameters->incremental_update())
4234 off = align_address(*poff, oshdrs->addralign());
4237 oshdrs->pre_finalize_data_size();
4238 off = this->allocate(oshdrs->data_size(), oshdrs->addralign(), *poff);
4240 gold_fallback(_("out of patch space for section header table; "
4241 "relink with --incremental-full"));
4242 gold_debug(DEBUG_INCREMENTAL,
4243 "create_shdrs: %08lx %08lx (section header table)",
4244 static_cast<long>(off),
4245 static_cast<long>(off + oshdrs->data_size()));
4247 oshdrs->set_address_and_file_offset(0, off);
4248 off += oshdrs->data_size();
4251 this->section_headers_ = oshdrs;
4254 // Count the allocated sections.
4257 Layout::allocated_output_section_count() const
4259 size_t section_count = 0;
4260 for (Segment_list::const_iterator p = this->segment_list_.begin();
4261 p != this->segment_list_.end();
4263 section_count += (*p)->output_section_count();
4264 return section_count;
4267 // Create the dynamic symbol table.
4268 // *PLOCAL_DYNAMIC_COUNT will be set to the number of local symbols
4269 // from input objects, and *PFORCED_LOCAL_DYNAMIC_COUNT will be set
4270 // to the number of global symbols that have been forced local.
4271 // We need to remember the former because the forced-local symbols are
4272 // written along with the global symbols in Symtab::write_globals().
4275 Layout::create_dynamic_symtab(const Input_objects* input_objects,
4276 Symbol_table* symtab,
4277 Output_section** pdynstr,
4278 unsigned int* plocal_dynamic_count,
4279 unsigned int* pforced_local_dynamic_count,
4280 std::vector<Symbol*>* pdynamic_symbols,
4281 Versions* pversions)
4283 // Count all the symbols in the dynamic symbol table, and set the
4284 // dynamic symbol indexes.
4286 // Skip symbol 0, which is always all zeroes.
4287 unsigned int index = 1;
4289 // Add STT_SECTION symbols for each Output section which needs one.
4290 for (Section_list::iterator p = this->section_list_.begin();
4291 p != this->section_list_.end();
4294 if (!(*p)->needs_dynsym_index())
4295 (*p)->set_dynsym_index(-1U);
4298 (*p)->set_dynsym_index(index);
4303 // Count the local symbols that need to go in the dynamic symbol table,
4304 // and set the dynamic symbol indexes.
4305 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
4306 p != input_objects->relobj_end();
4309 unsigned int new_index = (*p)->set_local_dynsym_indexes(index);
4313 unsigned int local_symcount = index;
4314 unsigned int forced_local_count = 0;
4316 index = symtab->set_dynsym_indexes(index, &forced_local_count,
4317 pdynamic_symbols, &this->dynpool_,
4320 *plocal_dynamic_count = local_symcount;
4321 *pforced_local_dynamic_count = forced_local_count;
4325 const int size = parameters->target().get_size();
4328 symsize = elfcpp::Elf_sizes<32>::sym_size;
4331 else if (size == 64)
4333 symsize = elfcpp::Elf_sizes<64>::sym_size;
4339 // Create the dynamic symbol table section.
4341 Output_section* dynsym = this->choose_output_section(NULL, ".dynsym",
4345 ORDER_DYNAMIC_LINKER,
4346 false, false, false);
4348 // Check for NULL as a linker script may discard .dynsym.
4351 Output_section_data* odata = new Output_data_fixed_space(index * symsize,
4354 dynsym->add_output_section_data(odata);
4356 dynsym->set_info(local_symcount + forced_local_count);
4357 dynsym->set_entsize(symsize);
4358 dynsym->set_addralign(align);
4360 this->dynsym_section_ = dynsym;
4363 Output_data_dynamic* const odyn = this->dynamic_data_;
4366 odyn->add_section_address(elfcpp::DT_SYMTAB, dynsym);
4367 odyn->add_constant(elfcpp::DT_SYMENT, symsize);
4370 // If there are more than SHN_LORESERVE allocated sections, we
4371 // create a .dynsym_shndx section. It is possible that we don't
4372 // need one, because it is possible that there are no dynamic
4373 // symbols in any of the sections with indexes larger than
4374 // SHN_LORESERVE. This is probably unusual, though, and at this
4375 // time we don't know the actual section indexes so it is
4376 // inconvenient to check.
4377 if (this->allocated_output_section_count() >= elfcpp::SHN_LORESERVE)
4379 Output_section* dynsym_xindex =
4380 this->choose_output_section(NULL, ".dynsym_shndx",
4381 elfcpp::SHT_SYMTAB_SHNDX,
4383 false, ORDER_DYNAMIC_LINKER, false, false,
4386 if (dynsym_xindex != NULL)
4388 this->dynsym_xindex_ = new Output_symtab_xindex(index);
4390 dynsym_xindex->add_output_section_data(this->dynsym_xindex_);
4392 dynsym_xindex->set_link_section(dynsym);
4393 dynsym_xindex->set_addralign(4);
4394 dynsym_xindex->set_entsize(4);
4396 dynsym_xindex->set_after_input_sections();
4398 // This tells the driver code to wait until the symbol table
4399 // has written out before writing out the postprocessing
4400 // sections, including the .dynsym_shndx section.
4401 this->any_postprocessing_sections_ = true;
4405 // Create the dynamic string table section.
4407 Output_section* dynstr = this->choose_output_section(NULL, ".dynstr",
4411 ORDER_DYNAMIC_LINKER,
4412 false, false, false);
4416 Output_section_data* strdata = new Output_data_strtab(&this->dynpool_);
4417 dynstr->add_output_section_data(strdata);
4420 dynsym->set_link_section(dynstr);
4421 if (this->dynamic_section_ != NULL)
4422 this->dynamic_section_->set_link_section(dynstr);
4426 odyn->add_section_address(elfcpp::DT_STRTAB, dynstr);
4427 odyn->add_section_size(elfcpp::DT_STRSZ, dynstr);
4431 // Create the hash tables. The Gnu-style hash table must be
4432 // built first, because it changes the order of the symbols
4433 // in the dynamic symbol table.
4435 if (strcmp(parameters->options().hash_style(), "gnu") == 0
4436 || strcmp(parameters->options().hash_style(), "both") == 0)
4438 unsigned char* phash;
4439 unsigned int hashlen;
4440 Dynobj::create_gnu_hash_table(*pdynamic_symbols,
4441 local_symcount + forced_local_count,
4444 Output_section* hashsec =
4445 this->choose_output_section(NULL, ".gnu.hash", elfcpp::SHT_GNU_HASH,
4446 elfcpp::SHF_ALLOC, false,
4447 ORDER_DYNAMIC_LINKER, false, false,
4450 Output_section_data* hashdata = new Output_data_const_buffer(phash,
4454 if (hashsec != NULL && hashdata != NULL)
4455 hashsec->add_output_section_data(hashdata);
4457 if (hashsec != NULL)
4460 hashsec->set_link_section(dynsym);
4462 // For a 64-bit target, the entries in .gnu.hash do not have
4463 // a uniform size, so we only set the entry size for a
4465 if (parameters->target().get_size() == 32)
4466 hashsec->set_entsize(4);
4469 odyn->add_section_address(elfcpp::DT_GNU_HASH, hashsec);
4473 if (strcmp(parameters->options().hash_style(), "sysv") == 0
4474 || strcmp(parameters->options().hash_style(), "both") == 0)
4476 unsigned char* phash;
4477 unsigned int hashlen;
4478 Dynobj::create_elf_hash_table(*pdynamic_symbols,
4479 local_symcount + forced_local_count,
4482 Output_section* hashsec =
4483 this->choose_output_section(NULL, ".hash", elfcpp::SHT_HASH,
4484 elfcpp::SHF_ALLOC, false,
4485 ORDER_DYNAMIC_LINKER, false, false,
4488 Output_section_data* hashdata = new Output_data_const_buffer(phash,
4492 if (hashsec != NULL && hashdata != NULL)
4493 hashsec->add_output_section_data(hashdata);
4495 if (hashsec != NULL)
4498 hashsec->set_link_section(dynsym);
4499 hashsec->set_entsize(parameters->target().hash_entry_size() / 8);
4503 odyn->add_section_address(elfcpp::DT_HASH, hashsec);
4507 // Assign offsets to each local portion of the dynamic symbol table.
4510 Layout::assign_local_dynsym_offsets(const Input_objects* input_objects)
4512 Output_section* dynsym = this->dynsym_section_;
4516 off_t off = dynsym->offset();
4518 // Skip the dummy symbol at the start of the section.
4519 off += dynsym->entsize();
4521 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
4522 p != input_objects->relobj_end();
4525 unsigned int count = (*p)->set_local_dynsym_offset(off);
4526 off += count * dynsym->entsize();
4530 // Create the version sections.
4533 Layout::create_version_sections(const Versions* versions,
4534 const Symbol_table* symtab,
4535 unsigned int local_symcount,
4536 const std::vector<Symbol*>& dynamic_symbols,
4537 const Output_section* dynstr)
4539 if (!versions->any_defs() && !versions->any_needs())
4542 switch (parameters->size_and_endianness())
4544 #ifdef HAVE_TARGET_32_LITTLE
4545 case Parameters::TARGET_32_LITTLE:
4546 this->sized_create_version_sections<32, false>(versions, symtab,
4548 dynamic_symbols, dynstr);
4551 #ifdef HAVE_TARGET_32_BIG
4552 case Parameters::TARGET_32_BIG:
4553 this->sized_create_version_sections<32, true>(versions, symtab,
4555 dynamic_symbols, dynstr);
4558 #ifdef HAVE_TARGET_64_LITTLE
4559 case Parameters::TARGET_64_LITTLE:
4560 this->sized_create_version_sections<64, false>(versions, symtab,
4562 dynamic_symbols, dynstr);
4565 #ifdef HAVE_TARGET_64_BIG
4566 case Parameters::TARGET_64_BIG:
4567 this->sized_create_version_sections<64, true>(versions, symtab,
4569 dynamic_symbols, dynstr);
4577 // Create the version sections, sized version.
4579 template<int size, bool big_endian>
4581 Layout::sized_create_version_sections(
4582 const Versions* versions,
4583 const Symbol_table* symtab,
4584 unsigned int local_symcount,
4585 const std::vector<Symbol*>& dynamic_symbols,
4586 const Output_section* dynstr)
4588 Output_section* vsec = this->choose_output_section(NULL, ".gnu.version",
4589 elfcpp::SHT_GNU_versym,
4592 ORDER_DYNAMIC_LINKER,
4593 false, false, false);
4595 // Check for NULL since a linker script may discard this section.
4598 unsigned char* vbuf;
4600 versions->symbol_section_contents<size, big_endian>(symtab,
4606 Output_section_data* vdata = new Output_data_const_buffer(vbuf, vsize, 2,
4609 vsec->add_output_section_data(vdata);
4610 vsec->set_entsize(2);
4611 vsec->set_link_section(this->dynsym_section_);
4614 Output_data_dynamic* const odyn = this->dynamic_data_;
4615 if (odyn != NULL && vsec != NULL)
4616 odyn->add_section_address(elfcpp::DT_VERSYM, vsec);
4618 if (versions->any_defs())
4620 Output_section* vdsec;
4621 vdsec = this->choose_output_section(NULL, ".gnu.version_d",
4622 elfcpp::SHT_GNU_verdef,
4624 false, ORDER_DYNAMIC_LINKER, false,
4629 unsigned char* vdbuf;
4630 unsigned int vdsize;
4631 unsigned int vdentries;
4632 versions->def_section_contents<size, big_endian>(&this->dynpool_,
4636 Output_section_data* vddata =
4637 new Output_data_const_buffer(vdbuf, vdsize, 4, "** version defs");
4639 vdsec->add_output_section_data(vddata);
4640 vdsec->set_link_section(dynstr);
4641 vdsec->set_info(vdentries);
4645 odyn->add_section_address(elfcpp::DT_VERDEF, vdsec);
4646 odyn->add_constant(elfcpp::DT_VERDEFNUM, vdentries);
4651 if (versions->any_needs())
4653 Output_section* vnsec;
4654 vnsec = this->choose_output_section(NULL, ".gnu.version_r",
4655 elfcpp::SHT_GNU_verneed,
4657 false, ORDER_DYNAMIC_LINKER, false,
4662 unsigned char* vnbuf;
4663 unsigned int vnsize;
4664 unsigned int vnentries;
4665 versions->need_section_contents<size, big_endian>(&this->dynpool_,
4669 Output_section_data* vndata =
4670 new Output_data_const_buffer(vnbuf, vnsize, 4, "** version refs");
4672 vnsec->add_output_section_data(vndata);
4673 vnsec->set_link_section(dynstr);
4674 vnsec->set_info(vnentries);
4678 odyn->add_section_address(elfcpp::DT_VERNEED, vnsec);
4679 odyn->add_constant(elfcpp::DT_VERNEEDNUM, vnentries);
4685 // Create the .interp section and PT_INTERP segment.
4688 Layout::create_interp(const Target* target)
4690 gold_assert(this->interp_segment_ == NULL);
4692 const char* interp = parameters->options().dynamic_linker();
4695 interp = target->dynamic_linker();
4696 gold_assert(interp != NULL);
4699 size_t len = strlen(interp) + 1;
4701 Output_section_data* odata = new Output_data_const(interp, len, 1);
4703 Output_section* osec = this->choose_output_section(NULL, ".interp",
4704 elfcpp::SHT_PROGBITS,
4706 false, ORDER_INTERP,
4707 false, false, false);
4709 osec->add_output_section_data(odata);
4712 // Add dynamic tags for the PLT and the dynamic relocs. This is
4713 // called by the target-specific code. This does nothing if not doing
4716 // USE_REL is true for REL relocs rather than RELA relocs.
4718 // If PLT_GOT is not NULL, then DT_PLTGOT points to it.
4720 // If PLT_REL is not NULL, it is used for DT_PLTRELSZ, and DT_JMPREL,
4721 // and we also set DT_PLTREL. We use PLT_REL's output section, since
4722 // some targets have multiple reloc sections in PLT_REL.
4724 // If DYN_REL is not NULL, it is used for DT_REL/DT_RELA,
4725 // DT_RELSZ/DT_RELASZ, DT_RELENT/DT_RELAENT. Again we use the output
4728 // If ADD_DEBUG is true, we add a DT_DEBUG entry when generating an
4732 Layout::add_target_dynamic_tags(bool use_rel, const Output_data* plt_got,
4733 const Output_data* plt_rel,
4734 const Output_data_reloc_generic* dyn_rel,
4735 bool add_debug, bool dynrel_includes_plt)
4737 Output_data_dynamic* odyn = this->dynamic_data_;
4741 if (plt_got != NULL && plt_got->output_section() != NULL)
4742 odyn->add_section_address(elfcpp::DT_PLTGOT, plt_got);
4744 if (plt_rel != NULL && plt_rel->output_section() != NULL)
4746 odyn->add_section_size(elfcpp::DT_PLTRELSZ, plt_rel->output_section());
4747 odyn->add_section_address(elfcpp::DT_JMPREL, plt_rel->output_section());
4748 odyn->add_constant(elfcpp::DT_PLTREL,
4749 use_rel ? elfcpp::DT_REL : elfcpp::DT_RELA);
4752 if ((dyn_rel != NULL && dyn_rel->output_section() != NULL)
4753 || (dynrel_includes_plt
4755 && plt_rel->output_section() != NULL))
4757 bool have_dyn_rel = dyn_rel != NULL && dyn_rel->output_section() != NULL;
4758 bool have_plt_rel = plt_rel != NULL && plt_rel->output_section() != NULL;
4759 odyn->add_section_address(use_rel ? elfcpp::DT_REL : elfcpp::DT_RELA,
4761 ? dyn_rel->output_section()
4762 : plt_rel->output_section()));
4763 elfcpp::DT size_tag = use_rel ? elfcpp::DT_RELSZ : elfcpp::DT_RELASZ;
4764 if (have_dyn_rel && have_plt_rel && dynrel_includes_plt)
4765 odyn->add_section_size(size_tag,
4766 dyn_rel->output_section(),
4767 plt_rel->output_section());
4768 else if (have_dyn_rel)
4769 odyn->add_section_size(size_tag, dyn_rel->output_section());
4771 odyn->add_section_size(size_tag, plt_rel->output_section());
4772 const int size = parameters->target().get_size();
4777 rel_tag = elfcpp::DT_RELENT;
4779 rel_size = Reloc_types<elfcpp::SHT_REL, 32, false>::reloc_size;
4780 else if (size == 64)
4781 rel_size = Reloc_types<elfcpp::SHT_REL, 64, false>::reloc_size;
4787 rel_tag = elfcpp::DT_RELAENT;
4789 rel_size = Reloc_types<elfcpp::SHT_RELA, 32, false>::reloc_size;
4790 else if (size == 64)
4791 rel_size = Reloc_types<elfcpp::SHT_RELA, 64, false>::reloc_size;
4795 odyn->add_constant(rel_tag, rel_size);
4797 if (parameters->options().combreloc() && have_dyn_rel)
4799 size_t c = dyn_rel->relative_reloc_count();
4801 odyn->add_constant((use_rel
4802 ? elfcpp::DT_RELCOUNT
4803 : elfcpp::DT_RELACOUNT),
4808 if (add_debug && !parameters->options().shared())
4810 // The value of the DT_DEBUG tag is filled in by the dynamic
4811 // linker at run time, and used by the debugger.
4812 odyn->add_constant(elfcpp::DT_DEBUG, 0);
4817 Layout::add_target_specific_dynamic_tag(elfcpp::DT tag, unsigned int val)
4819 Output_data_dynamic* odyn = this->dynamic_data_;
4822 odyn->add_constant(tag, val);
4825 // Finish the .dynamic section and PT_DYNAMIC segment.
4828 Layout::finish_dynamic_section(const Input_objects* input_objects,
4829 const Symbol_table* symtab)
4831 if (!this->script_options_->saw_phdrs_clause()
4832 && this->dynamic_section_ != NULL)
4834 Output_segment* oseg = this->make_output_segment(elfcpp::PT_DYNAMIC,
4837 oseg->add_output_section_to_nonload(this->dynamic_section_,
4838 elfcpp::PF_R | elfcpp::PF_W);
4841 Output_data_dynamic* const odyn = this->dynamic_data_;
4845 for (Input_objects::Dynobj_iterator p = input_objects->dynobj_begin();
4846 p != input_objects->dynobj_end();
4849 if (!(*p)->is_needed() && (*p)->as_needed())
4851 // This dynamic object was linked with --as-needed, but it
4856 odyn->add_string(elfcpp::DT_NEEDED, (*p)->soname());
4859 if (parameters->options().shared())
4861 const char* soname = parameters->options().soname();
4863 odyn->add_string(elfcpp::DT_SONAME, soname);
4866 Symbol* sym = symtab->lookup(parameters->options().init());
4867 if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj())
4868 odyn->add_symbol(elfcpp::DT_INIT, sym);
4870 sym = symtab->lookup(parameters->options().fini());
4871 if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj())
4872 odyn->add_symbol(elfcpp::DT_FINI, sym);
4874 // Look for .init_array, .preinit_array and .fini_array by checking
4876 for(Layout::Section_list::const_iterator p = this->section_list_.begin();
4877 p != this->section_list_.end();
4879 switch((*p)->type())
4881 case elfcpp::SHT_FINI_ARRAY:
4882 odyn->add_section_address(elfcpp::DT_FINI_ARRAY, *p);
4883 odyn->add_section_size(elfcpp::DT_FINI_ARRAYSZ, *p);
4885 case elfcpp::SHT_INIT_ARRAY:
4886 odyn->add_section_address(elfcpp::DT_INIT_ARRAY, *p);
4887 odyn->add_section_size(elfcpp::DT_INIT_ARRAYSZ, *p);
4889 case elfcpp::SHT_PREINIT_ARRAY:
4890 odyn->add_section_address(elfcpp::DT_PREINIT_ARRAY, *p);
4891 odyn->add_section_size(elfcpp::DT_PREINIT_ARRAYSZ, *p);
4897 // Add a DT_RPATH entry if needed.
4898 const General_options::Dir_list& rpath(parameters->options().rpath());
4901 std::string rpath_val;
4902 for (General_options::Dir_list::const_iterator p = rpath.begin();
4906 if (rpath_val.empty())
4907 rpath_val = p->name();
4910 // Eliminate duplicates.
4911 General_options::Dir_list::const_iterator q;
4912 for (q = rpath.begin(); q != p; ++q)
4913 if (q->name() == p->name())
4918 rpath_val += p->name();
4923 if (!parameters->options().enable_new_dtags())
4924 odyn->add_string(elfcpp::DT_RPATH, rpath_val);
4926 odyn->add_string(elfcpp::DT_RUNPATH, rpath_val);
4929 // Look for text segments that have dynamic relocations.
4930 bool have_textrel = false;
4931 if (!this->script_options_->saw_sections_clause())
4933 for (Segment_list::const_iterator p = this->segment_list_.begin();
4934 p != this->segment_list_.end();
4937 if ((*p)->type() == elfcpp::PT_LOAD
4938 && ((*p)->flags() & elfcpp::PF_W) == 0
4939 && (*p)->has_dynamic_reloc())
4941 have_textrel = true;
4948 // We don't know the section -> segment mapping, so we are
4949 // conservative and just look for readonly sections with
4950 // relocations. If those sections wind up in writable segments,
4951 // then we have created an unnecessary DT_TEXTREL entry.
4952 for (Section_list::const_iterator p = this->section_list_.begin();
4953 p != this->section_list_.end();
4956 if (((*p)->flags() & elfcpp::SHF_ALLOC) != 0
4957 && ((*p)->flags() & elfcpp::SHF_WRITE) == 0
4958 && (*p)->has_dynamic_reloc())
4960 have_textrel = true;
4966 if (parameters->options().filter() != NULL)
4967 odyn->add_string(elfcpp::DT_FILTER, parameters->options().filter());
4968 if (parameters->options().any_auxiliary())
4970 for (options::String_set::const_iterator p =
4971 parameters->options().auxiliary_begin();
4972 p != parameters->options().auxiliary_end();
4974 odyn->add_string(elfcpp::DT_AUXILIARY, *p);
4977 // Add a DT_FLAGS entry if necessary.
4978 unsigned int flags = 0;
4981 // Add a DT_TEXTREL for compatibility with older loaders.
4982 odyn->add_constant(elfcpp::DT_TEXTREL, 0);
4983 flags |= elfcpp::DF_TEXTREL;
4985 if (parameters->options().text())
4986 gold_error(_("read-only segment has dynamic relocations"));
4987 else if (parameters->options().warn_shared_textrel()
4988 && parameters->options().shared())
4989 gold_warning(_("shared library text segment is not shareable"));
4991 if (parameters->options().shared() && this->has_static_tls())
4992 flags |= elfcpp::DF_STATIC_TLS;
4993 if (parameters->options().origin())
4994 flags |= elfcpp::DF_ORIGIN;
4995 if (parameters->options().Bsymbolic()
4996 && !parameters->options().have_dynamic_list())
4998 flags |= elfcpp::DF_SYMBOLIC;
4999 // Add DT_SYMBOLIC for compatibility with older loaders.
5000 odyn->add_constant(elfcpp::DT_SYMBOLIC, 0);
5002 if (parameters->options().now())
5003 flags |= elfcpp::DF_BIND_NOW;
5005 odyn->add_constant(elfcpp::DT_FLAGS, flags);
5008 if (parameters->options().global())
5009 flags |= elfcpp::DF_1_GLOBAL;
5010 if (parameters->options().initfirst())
5011 flags |= elfcpp::DF_1_INITFIRST;
5012 if (parameters->options().interpose())
5013 flags |= elfcpp::DF_1_INTERPOSE;
5014 if (parameters->options().loadfltr())
5015 flags |= elfcpp::DF_1_LOADFLTR;
5016 if (parameters->options().nodefaultlib())
5017 flags |= elfcpp::DF_1_NODEFLIB;
5018 if (parameters->options().nodelete())
5019 flags |= elfcpp::DF_1_NODELETE;
5020 if (parameters->options().nodlopen())
5021 flags |= elfcpp::DF_1_NOOPEN;
5022 if (parameters->options().nodump())
5023 flags |= elfcpp::DF_1_NODUMP;
5024 if (!parameters->options().shared())
5025 flags &= ~(elfcpp::DF_1_INITFIRST
5026 | elfcpp::DF_1_NODELETE
5027 | elfcpp::DF_1_NOOPEN);
5028 if (parameters->options().origin())
5029 flags |= elfcpp::DF_1_ORIGIN;
5030 if (parameters->options().now())
5031 flags |= elfcpp::DF_1_NOW;
5032 if (parameters->options().Bgroup())
5033 flags |= elfcpp::DF_1_GROUP;
5035 odyn->add_constant(elfcpp::DT_FLAGS_1, flags);
5038 // Set the size of the _DYNAMIC symbol table to be the size of the
5042 Layout::set_dynamic_symbol_size(const Symbol_table* symtab)
5044 Output_data_dynamic* const odyn = this->dynamic_data_;
5047 odyn->finalize_data_size();
5048 if (this->dynamic_symbol_ == NULL)
5050 off_t data_size = odyn->data_size();
5051 const int size = parameters->target().get_size();
5053 symtab->get_sized_symbol<32>(this->dynamic_symbol_)->set_symsize(data_size);
5054 else if (size == 64)
5055 symtab->get_sized_symbol<64>(this->dynamic_symbol_)->set_symsize(data_size);
5060 // The mapping of input section name prefixes to output section names.
5061 // In some cases one prefix is itself a prefix of another prefix; in
5062 // such a case the longer prefix must come first. These prefixes are
5063 // based on the GNU linker default ELF linker script.
5065 #define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 }
5066 #define MAPPING_INIT_EXACT(f, t) { f, 0, t, sizeof(t) - 1 }
5067 const Layout::Section_name_mapping Layout::section_name_mapping[] =
5069 MAPPING_INIT(".text.", ".text"),
5070 MAPPING_INIT(".rodata.", ".rodata"),
5071 MAPPING_INIT(".data.rel.ro.local.", ".data.rel.ro.local"),
5072 MAPPING_INIT_EXACT(".data.rel.ro.local", ".data.rel.ro.local"),
5073 MAPPING_INIT(".data.rel.ro.", ".data.rel.ro"),
5074 MAPPING_INIT_EXACT(".data.rel.ro", ".data.rel.ro"),
5075 MAPPING_INIT(".data.", ".data"),
5076 MAPPING_INIT(".bss.", ".bss"),
5077 MAPPING_INIT(".tdata.", ".tdata"),
5078 MAPPING_INIT(".tbss.", ".tbss"),
5079 MAPPING_INIT(".init_array.", ".init_array"),
5080 MAPPING_INIT(".fini_array.", ".fini_array"),
5081 MAPPING_INIT(".sdata.", ".sdata"),
5082 MAPPING_INIT(".sbss.", ".sbss"),
5083 // FIXME: In the GNU linker, .sbss2 and .sdata2 are handled
5084 // differently depending on whether it is creating a shared library.
5085 MAPPING_INIT(".sdata2.", ".sdata"),
5086 MAPPING_INIT(".sbss2.", ".sbss"),
5087 MAPPING_INIT(".lrodata.", ".lrodata"),
5088 MAPPING_INIT(".ldata.", ".ldata"),
5089 MAPPING_INIT(".lbss.", ".lbss"),
5090 MAPPING_INIT(".gcc_except_table.", ".gcc_except_table"),
5091 MAPPING_INIT(".gnu.linkonce.d.rel.ro.local.", ".data.rel.ro.local"),
5092 MAPPING_INIT(".gnu.linkonce.d.rel.ro.", ".data.rel.ro"),
5093 MAPPING_INIT(".gnu.linkonce.t.", ".text"),
5094 MAPPING_INIT(".gnu.linkonce.r.", ".rodata"),
5095 MAPPING_INIT(".gnu.linkonce.d.", ".data"),
5096 MAPPING_INIT(".gnu.linkonce.b.", ".bss"),
5097 MAPPING_INIT(".gnu.linkonce.s.", ".sdata"),
5098 MAPPING_INIT(".gnu.linkonce.sb.", ".sbss"),
5099 MAPPING_INIT(".gnu.linkonce.s2.", ".sdata"),
5100 MAPPING_INIT(".gnu.linkonce.sb2.", ".sbss"),
5101 MAPPING_INIT(".gnu.linkonce.wi.", ".debug_info"),
5102 MAPPING_INIT(".gnu.linkonce.td.", ".tdata"),
5103 MAPPING_INIT(".gnu.linkonce.tb.", ".tbss"),
5104 MAPPING_INIT(".gnu.linkonce.lr.", ".lrodata"),
5105 MAPPING_INIT(".gnu.linkonce.l.", ".ldata"),
5106 MAPPING_INIT(".gnu.linkonce.lb.", ".lbss"),
5107 MAPPING_INIT(".ARM.extab", ".ARM.extab"),
5108 MAPPING_INIT(".gnu.linkonce.armextab.", ".ARM.extab"),
5109 MAPPING_INIT(".ARM.exidx", ".ARM.exidx"),
5110 MAPPING_INIT(".gnu.linkonce.armexidx.", ".ARM.exidx"),
5113 #undef MAPPING_INIT_EXACT
5115 const int Layout::section_name_mapping_count =
5116 (sizeof(Layout::section_name_mapping)
5117 / sizeof(Layout::section_name_mapping[0]));
5119 // Choose the output section name to use given an input section name.
5120 // Set *PLEN to the length of the name. *PLEN is initialized to the
5124 Layout::output_section_name(const Relobj* relobj, const char* name,
5127 // gcc 4.3 generates the following sorts of section names when it
5128 // needs a section name specific to a function:
5134 // .data.rel.local.FN
5136 // .data.rel.ro.local.FN
5143 // The GNU linker maps all of those to the part before the .FN,
5144 // except that .data.rel.local.FN is mapped to .data, and
5145 // .data.rel.ro.local.FN is mapped to .data.rel.ro. The sections
5146 // beginning with .data.rel.ro.local are grouped together.
5148 // For an anonymous namespace, the string FN can contain a '.'.
5150 // Also of interest: .rodata.strN.N, .rodata.cstN, both of which the
5151 // GNU linker maps to .rodata.
5153 // The .data.rel.ro sections are used with -z relro. The sections
5154 // are recognized by name. We use the same names that the GNU
5155 // linker does for these sections.
5157 // It is hard to handle this in a principled way, so we don't even
5158 // try. We use a table of mappings. If the input section name is
5159 // not found in the table, we simply use it as the output section
5162 const Section_name_mapping* psnm = section_name_mapping;
5163 for (int i = 0; i < section_name_mapping_count; ++i, ++psnm)
5165 if (psnm->fromlen > 0)
5167 if (strncmp(name, psnm->from, psnm->fromlen) == 0)
5169 *plen = psnm->tolen;
5175 if (strcmp(name, psnm->from) == 0)
5177 *plen = psnm->tolen;
5183 // As an additional complication, .ctors sections are output in
5184 // either .ctors or .init_array sections, and .dtors sections are
5185 // output in either .dtors or .fini_array sections.
5186 if (is_prefix_of(".ctors.", name) || is_prefix_of(".dtors.", name))
5188 if (parameters->options().ctors_in_init_array())
5191 return name[1] == 'c' ? ".init_array" : ".fini_array";
5196 return name[1] == 'c' ? ".ctors" : ".dtors";
5199 if (parameters->options().ctors_in_init_array()
5200 && (strcmp(name, ".ctors") == 0 || strcmp(name, ".dtors") == 0))
5202 // To make .init_array/.fini_array work with gcc we must exclude
5203 // .ctors and .dtors sections from the crtbegin and crtend
5206 || (!Layout::match_file_name(relobj, "crtbegin")
5207 && !Layout::match_file_name(relobj, "crtend")))
5210 return name[1] == 'c' ? ".init_array" : ".fini_array";
5217 // Return true if RELOBJ is an input file whose base name matches
5218 // FILE_NAME. The base name must have an extension of ".o", and must
5219 // be exactly FILE_NAME.o or FILE_NAME, one character, ".o". This is
5220 // to match crtbegin.o as well as crtbeginS.o without getting confused
5221 // by other possibilities. Overall matching the file name this way is
5222 // a dreadful hack, but the GNU linker does it in order to better
5223 // support gcc, and we need to be compatible.
5226 Layout::match_file_name(const Relobj* relobj, const char* match)
5228 const std::string& file_name(relobj->name());
5229 const char* base_name = lbasename(file_name.c_str());
5230 size_t match_len = strlen(match);
5231 if (strncmp(base_name, match, match_len) != 0)
5233 size_t base_len = strlen(base_name);
5234 if (base_len != match_len + 2 && base_len != match_len + 3)
5236 return memcmp(base_name + base_len - 2, ".o", 2) == 0;
5239 // Check if a comdat group or .gnu.linkonce section with the given
5240 // NAME is selected for the link. If there is already a section,
5241 // *KEPT_SECTION is set to point to the existing section and the
5242 // function returns false. Otherwise, OBJECT, SHNDX, IS_COMDAT, and
5243 // IS_GROUP_NAME are recorded for this NAME in the layout object,
5244 // *KEPT_SECTION is set to the internal copy and the function returns
5248 Layout::find_or_add_kept_section(const std::string& name,
5253 Kept_section** kept_section)
5255 // It's normal to see a couple of entries here, for the x86 thunk
5256 // sections. If we see more than a few, we're linking a C++
5257 // program, and we resize to get more space to minimize rehashing.
5258 if (this->signatures_.size() > 4
5259 && !this->resized_signatures_)
5261 reserve_unordered_map(&this->signatures_,
5262 this->number_of_input_files_ * 64);
5263 this->resized_signatures_ = true;
5266 Kept_section candidate;
5267 std::pair<Signatures::iterator, bool> ins =
5268 this->signatures_.insert(std::make_pair(name, candidate));
5270 if (kept_section != NULL)
5271 *kept_section = &ins.first->second;
5274 // This is the first time we've seen this signature.
5275 ins.first->second.set_object(object);
5276 ins.first->second.set_shndx(shndx);
5278 ins.first->second.set_is_comdat();
5280 ins.first->second.set_is_group_name();
5284 // We have already seen this signature.
5286 if (ins.first->second.is_group_name())
5288 // We've already seen a real section group with this signature.
5289 // If the kept group is from a plugin object, and we're in the
5290 // replacement phase, accept the new one as a replacement.
5291 if (ins.first->second.object() == NULL
5292 && parameters->options().plugins()->in_replacement_phase())
5294 ins.first->second.set_object(object);
5295 ins.first->second.set_shndx(shndx);
5300 else if (is_group_name)
5302 // This is a real section group, and we've already seen a
5303 // linkonce section with this signature. Record that we've seen
5304 // a section group, and don't include this section group.
5305 ins.first->second.set_is_group_name();
5310 // We've already seen a linkonce section and this is a linkonce
5311 // section. These don't block each other--this may be the same
5312 // symbol name with different section types.
5317 // Store the allocated sections into the section list.
5320 Layout::get_allocated_sections(Section_list* section_list) const
5322 for (Section_list::const_iterator p = this->section_list_.begin();
5323 p != this->section_list_.end();
5325 if (((*p)->flags() & elfcpp::SHF_ALLOC) != 0)
5326 section_list->push_back(*p);
5329 // Store the executable sections into the section list.
5332 Layout::get_executable_sections(Section_list* section_list) const
5334 for (Section_list::const_iterator p = this->section_list_.begin();
5335 p != this->section_list_.end();
5337 if (((*p)->flags() & (elfcpp::SHF_ALLOC | elfcpp::SHF_EXECINSTR))
5338 == (elfcpp::SHF_ALLOC | elfcpp::SHF_EXECINSTR))
5339 section_list->push_back(*p);
5342 // Create an output segment.
5345 Layout::make_output_segment(elfcpp::Elf_Word type, elfcpp::Elf_Word flags)
5347 gold_assert(!parameters->options().relocatable());
5348 Output_segment* oseg = new Output_segment(type, flags);
5349 this->segment_list_.push_back(oseg);
5351 if (type == elfcpp::PT_TLS)
5352 this->tls_segment_ = oseg;
5353 else if (type == elfcpp::PT_GNU_RELRO)
5354 this->relro_segment_ = oseg;
5355 else if (type == elfcpp::PT_INTERP)
5356 this->interp_segment_ = oseg;
5361 // Return the file offset of the normal symbol table.
5364 Layout::symtab_section_offset() const
5366 if (this->symtab_section_ != NULL)
5367 return this->symtab_section_->offset();
5371 // Return the section index of the normal symbol table. It may have
5372 // been stripped by the -s/--strip-all option.
5375 Layout::symtab_section_shndx() const
5377 if (this->symtab_section_ != NULL)
5378 return this->symtab_section_->out_shndx();
5382 // Write out the Output_sections. Most won't have anything to write,
5383 // since most of the data will come from input sections which are
5384 // handled elsewhere. But some Output_sections do have Output_data.
5387 Layout::write_output_sections(Output_file* of) const
5389 for (Section_list::const_iterator p = this->section_list_.begin();
5390 p != this->section_list_.end();
5393 if (!(*p)->after_input_sections())
5398 // Write out data not associated with a section or the symbol table.
5401 Layout::write_data(const Symbol_table* symtab, Output_file* of) const
5403 if (!parameters->options().strip_all())
5405 const Output_section* symtab_section = this->symtab_section_;
5406 for (Section_list::const_iterator p = this->section_list_.begin();
5407 p != this->section_list_.end();
5410 if ((*p)->needs_symtab_index())
5412 gold_assert(symtab_section != NULL);
5413 unsigned int index = (*p)->symtab_index();
5414 gold_assert(index > 0 && index != -1U);
5415 off_t off = (symtab_section->offset()
5416 + index * symtab_section->entsize());
5417 symtab->write_section_symbol(*p, this->symtab_xindex_, of, off);
5422 const Output_section* dynsym_section = this->dynsym_section_;
5423 for (Section_list::const_iterator p = this->section_list_.begin();
5424 p != this->section_list_.end();
5427 if ((*p)->needs_dynsym_index())
5429 gold_assert(dynsym_section != NULL);
5430 unsigned int index = (*p)->dynsym_index();
5431 gold_assert(index > 0 && index != -1U);
5432 off_t off = (dynsym_section->offset()
5433 + index * dynsym_section->entsize());
5434 symtab->write_section_symbol(*p, this->dynsym_xindex_, of, off);
5438 // Write out the Output_data which are not in an Output_section.
5439 for (Data_list::const_iterator p = this->special_output_list_.begin();
5440 p != this->special_output_list_.end();
5444 // Write out the Output_data which are not in an Output_section
5445 // and are regenerated in each iteration of relaxation.
5446 for (Data_list::const_iterator p = this->relax_output_list_.begin();
5447 p != this->relax_output_list_.end();
5452 // Write out the Output_sections which can only be written after the
5453 // input sections are complete.
5456 Layout::write_sections_after_input_sections(Output_file* of)
5458 // Determine the final section offsets, and thus the final output
5459 // file size. Note we finalize the .shstrab last, to allow the
5460 // after_input_section sections to modify their section-names before
5462 if (this->any_postprocessing_sections_)
5464 off_t off = this->output_file_size_;
5465 off = this->set_section_offsets(off, POSTPROCESSING_SECTIONS_PASS);
5467 // Now that we've finalized the names, we can finalize the shstrab.
5469 this->set_section_offsets(off,
5470 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS);
5472 if (off > this->output_file_size_)
5475 this->output_file_size_ = off;
5479 for (Section_list::const_iterator p = this->section_list_.begin();
5480 p != this->section_list_.end();
5483 if ((*p)->after_input_sections())
5487 this->section_headers_->write(of);
5490 // If a tree-style build ID was requested, the parallel part of that computation
5491 // is already done, and the final hash-of-hashes is computed here. For other
5492 // types of build IDs, all the work is done here.
5495 Layout::write_build_id(Output_file* of, unsigned char* array_of_hashes,
5496 size_t size_of_hashes) const
5498 if (this->build_id_note_ == NULL)
5501 unsigned char* ov = of->get_output_view(this->build_id_note_->offset(),
5502 this->build_id_note_->data_size());
5504 if (array_of_hashes == NULL)
5506 const size_t output_file_size = this->output_file_size();
5507 const unsigned char* iv = of->get_input_view(0, output_file_size);
5508 const char* style = parameters->options().build_id();
5510 // If we get here with style == "tree" then the output must be
5511 // too small for chunking, and we use SHA-1 in that case.
5512 if ((strcmp(style, "sha1") == 0) || (strcmp(style, "tree") == 0))
5513 sha1_buffer(reinterpret_cast<const char*>(iv), output_file_size, ov);
5514 else if (strcmp(style, "md5") == 0)
5515 md5_buffer(reinterpret_cast<const char*>(iv), output_file_size, ov);
5519 of->free_input_view(0, output_file_size, iv);
5523 // Non-overlapping substrings of the output file have been hashed.
5524 // Compute SHA-1 hash of the hashes.
5525 sha1_buffer(reinterpret_cast<const char*>(array_of_hashes),
5526 size_of_hashes, ov);
5527 delete[] array_of_hashes;
5530 of->write_output_view(this->build_id_note_->offset(),
5531 this->build_id_note_->data_size(),
5535 // Write out a binary file. This is called after the link is
5536 // complete. IN is the temporary output file we used to generate the
5537 // ELF code. We simply walk through the segments, read them from
5538 // their file offset in IN, and write them to their load address in
5539 // the output file. FIXME: with a bit more work, we could support
5540 // S-records and/or Intel hex format here.
5543 Layout::write_binary(Output_file* in) const
5545 gold_assert(parameters->options().oformat_enum()
5546 == General_options::OBJECT_FORMAT_BINARY);
5548 // Get the size of the binary file.
5549 uint64_t max_load_address = 0;
5550 for (Segment_list::const_iterator p = this->segment_list_.begin();
5551 p != this->segment_list_.end();
5554 if ((*p)->type() == elfcpp::PT_LOAD && (*p)->filesz() > 0)
5556 uint64_t max_paddr = (*p)->paddr() + (*p)->filesz();
5557 if (max_paddr > max_load_address)
5558 max_load_address = max_paddr;
5562 Output_file out(parameters->options().output_file_name());
5563 out.open(max_load_address);
5565 for (Segment_list::const_iterator p = this->segment_list_.begin();
5566 p != this->segment_list_.end();
5569 if ((*p)->type() == elfcpp::PT_LOAD && (*p)->filesz() > 0)
5571 const unsigned char* vin = in->get_input_view((*p)->offset(),
5573 unsigned char* vout = out.get_output_view((*p)->paddr(),
5575 memcpy(vout, vin, (*p)->filesz());
5576 out.write_output_view((*p)->paddr(), (*p)->filesz(), vout);
5577 in->free_input_view((*p)->offset(), (*p)->filesz(), vin);
5584 // Print the output sections to the map file.
5587 Layout::print_to_mapfile(Mapfile* mapfile) const
5589 for (Segment_list::const_iterator p = this->segment_list_.begin();
5590 p != this->segment_list_.end();
5592 (*p)->print_sections_to_mapfile(mapfile);
5593 for (Section_list::const_iterator p = this->unattached_section_list_.begin();
5594 p != this->unattached_section_list_.end();
5596 (*p)->print_to_mapfile(mapfile);
5599 // Print statistical information to stderr. This is used for --stats.
5602 Layout::print_stats() const
5604 this->namepool_.print_stats("section name pool");
5605 this->sympool_.print_stats("output symbol name pool");
5606 this->dynpool_.print_stats("dynamic name pool");
5608 for (Section_list::const_iterator p = this->section_list_.begin();
5609 p != this->section_list_.end();
5611 (*p)->print_merge_stats();
5614 // Write_sections_task methods.
5616 // We can always run this task.
5619 Write_sections_task::is_runnable()
5624 // We need to unlock both OUTPUT_SECTIONS_BLOCKER and FINAL_BLOCKER
5628 Write_sections_task::locks(Task_locker* tl)
5630 tl->add(this, this->output_sections_blocker_);
5631 if (this->input_sections_blocker_ != NULL)
5632 tl->add(this, this->input_sections_blocker_);
5633 tl->add(this, this->final_blocker_);
5636 // Run the task--write out the data.
5639 Write_sections_task::run(Workqueue*)
5641 this->layout_->write_output_sections(this->of_);
5644 // Write_data_task methods.
5646 // We can always run this task.
5649 Write_data_task::is_runnable()
5654 // We need to unlock FINAL_BLOCKER when finished.
5657 Write_data_task::locks(Task_locker* tl)
5659 tl->add(this, this->final_blocker_);
5662 // Run the task--write out the data.
5665 Write_data_task::run(Workqueue*)
5667 this->layout_->write_data(this->symtab_, this->of_);
5670 // Write_symbols_task methods.
5672 // We can always run this task.
5675 Write_symbols_task::is_runnable()
5680 // We need to unlock FINAL_BLOCKER when finished.
5683 Write_symbols_task::locks(Task_locker* tl)
5685 tl->add(this, this->final_blocker_);
5688 // Run the task--write out the symbols.
5691 Write_symbols_task::run(Workqueue*)
5693 this->symtab_->write_globals(this->sympool_, this->dynpool_,
5694 this->layout_->symtab_xindex(),
5695 this->layout_->dynsym_xindex(), this->of_);
5698 // Write_after_input_sections_task methods.
5700 // We can only run this task after the input sections have completed.
5703 Write_after_input_sections_task::is_runnable()
5705 if (this->input_sections_blocker_->is_blocked())
5706 return this->input_sections_blocker_;
5710 // We need to unlock FINAL_BLOCKER when finished.
5713 Write_after_input_sections_task::locks(Task_locker* tl)
5715 tl->add(this, this->final_blocker_);
5721 Write_after_input_sections_task::run(Workqueue*)
5723 this->layout_->write_sections_after_input_sections(this->of_);
5726 // Build IDs can be computed as a "flat" sha1 or md5 of a string of bytes,
5727 // or as a "tree" where each chunk of the string is hashed and then those
5728 // hashes are put into a (much smaller) string which is hashed with sha1.
5729 // We compute a checksum over the entire file because that is simplest.
5732 Build_id_task_runner::run(Workqueue* workqueue, const Task*)
5734 Task_token* post_hash_tasks_blocker = new Task_token(true);
5735 const Layout* layout = this->layout_;
5736 Output_file* of = this->of_;
5737 const size_t filesize = (layout->output_file_size() <= 0 ? 0
5738 : static_cast<size_t>(layout->output_file_size()));
5739 unsigned char* array_of_hashes = NULL;
5740 size_t size_of_hashes = 0;
5742 if (strcmp(this->options_->build_id(), "tree") == 0
5743 && this->options_->build_id_chunk_size_for_treehash() > 0
5745 && (filesize >= this->options_->build_id_min_file_size_for_treehash()))
5747 static const size_t MD5_OUTPUT_SIZE_IN_BYTES = 16;
5748 const size_t chunk_size =
5749 this->options_->build_id_chunk_size_for_treehash();
5750 const size_t num_hashes = ((filesize - 1) / chunk_size) + 1;
5751 post_hash_tasks_blocker->add_blockers(num_hashes);
5752 size_of_hashes = num_hashes * MD5_OUTPUT_SIZE_IN_BYTES;
5753 array_of_hashes = new unsigned char[size_of_hashes];
5754 unsigned char *dst = array_of_hashes;
5755 for (size_t i = 0, src_offset = 0; i < num_hashes;
5756 i++, dst += MD5_OUTPUT_SIZE_IN_BYTES, src_offset += chunk_size)
5758 size_t size = std::min(chunk_size, filesize - src_offset);
5759 workqueue->queue(new Hash_task(of,
5763 post_hash_tasks_blocker));
5767 // Queue the final task to write the build id and close the output file.
5768 workqueue->queue(new Task_function(new Close_task_runner(this->options_,
5773 post_hash_tasks_blocker,
5774 "Task_function Close_task_runner"));
5777 // Close_task_runner methods.
5779 // Finish up the build ID computation, if necessary, and write a binary file,
5780 // if necessary. Then close the output file.
5783 Close_task_runner::run(Workqueue*, const Task*)
5785 // At this point the multi-threaded part of the build ID computation,
5786 // if any, is done. See Build_id_task_runner.
5787 this->layout_->write_build_id(this->of_, this->array_of_hashes_,
5788 this->size_of_hashes_);
5790 // If we've been asked to create a binary file, we do so here.
5791 if (this->options_->oformat_enum() != General_options::OBJECT_FORMAT_ELF)
5792 this->layout_->write_binary(this->of_);
5797 // Instantiate the templates we need. We could use the configure
5798 // script to restrict this to only the ones for implemented targets.
5800 #ifdef HAVE_TARGET_32_LITTLE
5803 Layout::init_fixed_output_section<32, false>(
5805 elfcpp::Shdr<32, false>& shdr);
5808 #ifdef HAVE_TARGET_32_BIG
5811 Layout::init_fixed_output_section<32, true>(
5813 elfcpp::Shdr<32, true>& shdr);
5816 #ifdef HAVE_TARGET_64_LITTLE
5819 Layout::init_fixed_output_section<64, false>(
5821 elfcpp::Shdr<64, false>& shdr);
5824 #ifdef HAVE_TARGET_64_BIG
5827 Layout::init_fixed_output_section<64, true>(
5829 elfcpp::Shdr<64, true>& shdr);
5832 #ifdef HAVE_TARGET_32_LITTLE
5835 Layout::layout<32, false>(Sized_relobj_file<32, false>* object,
5838 const elfcpp::Shdr<32, false>& shdr,
5839 unsigned int, unsigned int, off_t*);
5842 #ifdef HAVE_TARGET_32_BIG
5845 Layout::layout<32, true>(Sized_relobj_file<32, true>* object,
5848 const elfcpp::Shdr<32, true>& shdr,
5849 unsigned int, unsigned int, off_t*);
5852 #ifdef HAVE_TARGET_64_LITTLE
5855 Layout::layout<64, false>(Sized_relobj_file<64, false>* object,
5858 const elfcpp::Shdr<64, false>& shdr,
5859 unsigned int, unsigned int, off_t*);
5862 #ifdef HAVE_TARGET_64_BIG
5865 Layout::layout<64, true>(Sized_relobj_file<64, true>* object,
5868 const elfcpp::Shdr<64, true>& shdr,
5869 unsigned int, unsigned int, off_t*);
5872 #ifdef HAVE_TARGET_32_LITTLE
5875 Layout::layout_reloc<32, false>(Sized_relobj_file<32, false>* object,
5876 unsigned int reloc_shndx,
5877 const elfcpp::Shdr<32, false>& shdr,
5878 Output_section* data_section,
5879 Relocatable_relocs* rr);
5882 #ifdef HAVE_TARGET_32_BIG
5885 Layout::layout_reloc<32, true>(Sized_relobj_file<32, true>* object,
5886 unsigned int reloc_shndx,
5887 const elfcpp::Shdr<32, true>& shdr,
5888 Output_section* data_section,
5889 Relocatable_relocs* rr);
5892 #ifdef HAVE_TARGET_64_LITTLE
5895 Layout::layout_reloc<64, false>(Sized_relobj_file<64, false>* object,
5896 unsigned int reloc_shndx,
5897 const elfcpp::Shdr<64, false>& shdr,
5898 Output_section* data_section,
5899 Relocatable_relocs* rr);
5902 #ifdef HAVE_TARGET_64_BIG
5905 Layout::layout_reloc<64, true>(Sized_relobj_file<64, true>* object,
5906 unsigned int reloc_shndx,
5907 const elfcpp::Shdr<64, true>& shdr,
5908 Output_section* data_section,
5909 Relocatable_relocs* rr);
5912 #ifdef HAVE_TARGET_32_LITTLE
5915 Layout::layout_group<32, false>(Symbol_table* symtab,
5916 Sized_relobj_file<32, false>* object,
5918 const char* group_section_name,
5919 const char* signature,
5920 const elfcpp::Shdr<32, false>& shdr,
5921 elfcpp::Elf_Word flags,
5922 std::vector<unsigned int>* shndxes);
5925 #ifdef HAVE_TARGET_32_BIG
5928 Layout::layout_group<32, true>(Symbol_table* symtab,
5929 Sized_relobj_file<32, true>* object,
5931 const char* group_section_name,
5932 const char* signature,
5933 const elfcpp::Shdr<32, true>& shdr,
5934 elfcpp::Elf_Word flags,
5935 std::vector<unsigned int>* shndxes);
5938 #ifdef HAVE_TARGET_64_LITTLE
5941 Layout::layout_group<64, false>(Symbol_table* symtab,
5942 Sized_relobj_file<64, false>* object,
5944 const char* group_section_name,
5945 const char* signature,
5946 const elfcpp::Shdr<64, false>& shdr,
5947 elfcpp::Elf_Word flags,
5948 std::vector<unsigned int>* shndxes);
5951 #ifdef HAVE_TARGET_64_BIG
5954 Layout::layout_group<64, true>(Symbol_table* symtab,
5955 Sized_relobj_file<64, true>* object,
5957 const char* group_section_name,
5958 const char* signature,
5959 const elfcpp::Shdr<64, true>& shdr,
5960 elfcpp::Elf_Word flags,
5961 std::vector<unsigned int>* shndxes);
5964 #ifdef HAVE_TARGET_32_LITTLE
5967 Layout::layout_eh_frame<32, false>(Sized_relobj_file<32, false>* object,
5968 const unsigned char* symbols,
5970 const unsigned char* symbol_names,
5971 off_t symbol_names_size,
5973 const elfcpp::Shdr<32, false>& shdr,
5974 unsigned int reloc_shndx,
5975 unsigned int reloc_type,
5979 #ifdef HAVE_TARGET_32_BIG
5982 Layout::layout_eh_frame<32, true>(Sized_relobj_file<32, true>* object,
5983 const unsigned char* symbols,
5985 const unsigned char* symbol_names,
5986 off_t symbol_names_size,
5988 const elfcpp::Shdr<32, true>& shdr,
5989 unsigned int reloc_shndx,
5990 unsigned int reloc_type,
5994 #ifdef HAVE_TARGET_64_LITTLE
5997 Layout::layout_eh_frame<64, false>(Sized_relobj_file<64, false>* object,
5998 const unsigned char* symbols,
6000 const unsigned char* symbol_names,
6001 off_t symbol_names_size,
6003 const elfcpp::Shdr<64, false>& shdr,
6004 unsigned int reloc_shndx,
6005 unsigned int reloc_type,
6009 #ifdef HAVE_TARGET_64_BIG
6012 Layout::layout_eh_frame<64, true>(Sized_relobj_file<64, true>* object,
6013 const unsigned char* symbols,
6015 const unsigned char* symbol_names,
6016 off_t symbol_names_size,
6018 const elfcpp::Shdr<64, true>& shdr,
6019 unsigned int reloc_shndx,
6020 unsigned int reloc_type,
6024 #ifdef HAVE_TARGET_32_LITTLE
6027 Layout::add_to_gdb_index(bool is_type_unit,
6028 Sized_relobj<32, false>* object,
6029 const unsigned char* symbols,
6032 unsigned int reloc_shndx,
6033 unsigned int reloc_type);
6036 #ifdef HAVE_TARGET_32_BIG
6039 Layout::add_to_gdb_index(bool is_type_unit,
6040 Sized_relobj<32, true>* object,
6041 const unsigned char* symbols,
6044 unsigned int reloc_shndx,
6045 unsigned int reloc_type);
6048 #ifdef HAVE_TARGET_64_LITTLE
6051 Layout::add_to_gdb_index(bool is_type_unit,
6052 Sized_relobj<64, false>* object,
6053 const unsigned char* symbols,
6056 unsigned int reloc_shndx,
6057 unsigned int reloc_type);
6060 #ifdef HAVE_TARGET_64_BIG
6063 Layout::add_to_gdb_index(bool is_type_unit,
6064 Sized_relobj<64, true>* object,
6065 const unsigned char* symbols,
6068 unsigned int reloc_shndx,
6069 unsigned int reloc_type);
6072 } // End namespace gold.