1 // layout.cc -- lay out output file sections for gold
3 // Copyright 2006, 2007, 2008, 2009, 2010, 2011, 2012
4 // Free Software Foundation, Inc.
5 // Written by Ian Lance Taylor <iant@google.com>.
7 // This file is part of gold.
9 // This program is free software; you can redistribute it and/or modify
10 // it under the terms of the GNU General Public License as published by
11 // the Free Software Foundation; either version 3 of the License, or
12 // (at your option) any later version.
14 // This program is distributed in the hope that it will be useful,
15 // but WITHOUT ANY WARRANTY; without even the implied warranty of
16 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 // GNU General Public License for more details.
19 // You should have received a copy of the GNU General Public License
20 // along with this program; if not, write to the Free Software
21 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
22 // MA 02110-1301, USA.
35 #include "libiberty.h"
39 #include "parameters.h"
43 #include "script-sections.h"
48 #include "gdb-index.h"
49 #include "compressed_output.h"
50 #include "reduced_debug_output.h"
53 #include "descriptors.h"
55 #include "incremental.h"
63 // The total number of free lists used.
64 unsigned int Free_list::num_lists = 0;
65 // The total number of free list nodes used.
66 unsigned int Free_list::num_nodes = 0;
67 // The total number of calls to Free_list::remove.
68 unsigned int Free_list::num_removes = 0;
69 // The total number of nodes visited during calls to Free_list::remove.
70 unsigned int Free_list::num_remove_visits = 0;
71 // The total number of calls to Free_list::allocate.
72 unsigned int Free_list::num_allocates = 0;
73 // The total number of nodes visited during calls to Free_list::allocate.
74 unsigned int Free_list::num_allocate_visits = 0;
76 // Initialize the free list. Creates a single free list node that
77 // describes the entire region of length LEN. If EXTEND is true,
78 // allocate() is allowed to extend the region beyond its initial
82 Free_list::init(off_t len, bool extend)
84 this->list_.push_front(Free_list_node(0, len));
85 this->last_remove_ = this->list_.begin();
86 this->extend_ = extend;
88 ++Free_list::num_lists;
89 ++Free_list::num_nodes;
92 // Remove a chunk from the free list. Because we start with a single
93 // node that covers the entire section, and remove chunks from it one
94 // at a time, we do not need to coalesce chunks or handle cases that
95 // span more than one free node. We expect to remove chunks from the
96 // free list in order, and we expect to have only a few chunks of free
97 // space left (corresponding to files that have changed since the last
98 // incremental link), so a simple linear list should provide sufficient
102 Free_list::remove(off_t start, off_t end)
106 gold_assert(start < end);
108 ++Free_list::num_removes;
110 Iterator p = this->last_remove_;
111 if (p->start_ > start)
112 p = this->list_.begin();
114 for (; p != this->list_.end(); ++p)
116 ++Free_list::num_remove_visits;
117 // Find a node that wholly contains the indicated region.
118 if (p->start_ <= start && p->end_ >= end)
120 // Case 1: the indicated region spans the whole node.
121 // Add some fuzz to avoid creating tiny free chunks.
122 if (p->start_ + 3 >= start && p->end_ <= end + 3)
123 p = this->list_.erase(p);
124 // Case 2: remove a chunk from the start of the node.
125 else if (p->start_ + 3 >= start)
127 // Case 3: remove a chunk from the end of the node.
128 else if (p->end_ <= end + 3)
130 // Case 4: remove a chunk from the middle, and split
131 // the node into two.
134 Free_list_node newnode(p->start_, start);
136 this->list_.insert(p, newnode);
137 ++Free_list::num_nodes;
139 this->last_remove_ = p;
144 // Did not find a node containing the given chunk. This could happen
145 // because a small chunk was already removed due to the fuzz.
146 gold_debug(DEBUG_INCREMENTAL,
147 "Free_list::remove(%d,%d) not found",
148 static_cast<int>(start), static_cast<int>(end));
151 // Allocate a chunk of size LEN from the free list. Returns -1ULL
152 // if a sufficiently large chunk of free space is not found.
153 // We use a simple first-fit algorithm.
156 Free_list::allocate(off_t len, uint64_t align, off_t minoff)
158 gold_debug(DEBUG_INCREMENTAL,
159 "Free_list::allocate(%08lx, %d, %08lx)",
160 static_cast<long>(len), static_cast<int>(align),
161 static_cast<long>(minoff));
163 return align_address(minoff, align);
165 ++Free_list::num_allocates;
167 // We usually want to drop free chunks smaller than 4 bytes.
168 // If we need to guarantee a minimum hole size, though, we need
169 // to keep track of all free chunks.
170 const int fuzz = this->min_hole_ > 0 ? 0 : 3;
172 for (Iterator p = this->list_.begin(); p != this->list_.end(); ++p)
174 ++Free_list::num_allocate_visits;
175 off_t start = p->start_ > minoff ? p->start_ : minoff;
176 start = align_address(start, align);
177 off_t end = start + len;
178 if (end > p->end_ && p->end_ == this->length_ && this->extend_)
183 if (end == p->end_ || (end <= p->end_ - this->min_hole_))
185 if (p->start_ + fuzz >= start && p->end_ <= end + fuzz)
186 this->list_.erase(p);
187 else if (p->start_ + fuzz >= start)
189 else if (p->end_ <= end + fuzz)
193 Free_list_node newnode(p->start_, start);
195 this->list_.insert(p, newnode);
196 ++Free_list::num_nodes;
203 off_t start = align_address(this->length_, align);
204 this->length_ = start + len;
210 // Dump the free list (for debugging).
214 gold_info("Free list:\n start end length\n");
215 for (Iterator p = this->list_.begin(); p != this->list_.end(); ++p)
216 gold_info(" %08lx %08lx %08lx", static_cast<long>(p->start_),
217 static_cast<long>(p->end_),
218 static_cast<long>(p->end_ - p->start_));
221 // Print the statistics for the free lists.
223 Free_list::print_stats()
225 fprintf(stderr, _("%s: total free lists: %u\n"),
226 program_name, Free_list::num_lists);
227 fprintf(stderr, _("%s: total free list nodes: %u\n"),
228 program_name, Free_list::num_nodes);
229 fprintf(stderr, _("%s: calls to Free_list::remove: %u\n"),
230 program_name, Free_list::num_removes);
231 fprintf(stderr, _("%s: nodes visited: %u\n"),
232 program_name, Free_list::num_remove_visits);
233 fprintf(stderr, _("%s: calls to Free_list::allocate: %u\n"),
234 program_name, Free_list::num_allocates);
235 fprintf(stderr, _("%s: nodes visited: %u\n"),
236 program_name, Free_list::num_allocate_visits);
239 // Layout::Relaxation_debug_check methods.
241 // Check that sections and special data are in reset states.
242 // We do not save states for Output_sections and special Output_data.
243 // So we check that they have not assigned any addresses or offsets.
244 // clean_up_after_relaxation simply resets their addresses and offsets.
246 Layout::Relaxation_debug_check::check_output_data_for_reset_values(
247 const Layout::Section_list& sections,
248 const Layout::Data_list& special_outputs)
250 for(Layout::Section_list::const_iterator p = sections.begin();
253 gold_assert((*p)->address_and_file_offset_have_reset_values());
255 for(Layout::Data_list::const_iterator p = special_outputs.begin();
256 p != special_outputs.end();
258 gold_assert((*p)->address_and_file_offset_have_reset_values());
261 // Save information of SECTIONS for checking later.
264 Layout::Relaxation_debug_check::read_sections(
265 const Layout::Section_list& sections)
267 for(Layout::Section_list::const_iterator p = sections.begin();
271 Output_section* os = *p;
273 info.output_section = os;
274 info.address = os->is_address_valid() ? os->address() : 0;
275 info.data_size = os->is_data_size_valid() ? os->data_size() : -1;
276 info.offset = os->is_offset_valid()? os->offset() : -1 ;
277 this->section_infos_.push_back(info);
281 // Verify SECTIONS using previously recorded information.
284 Layout::Relaxation_debug_check::verify_sections(
285 const Layout::Section_list& sections)
288 for(Layout::Section_list::const_iterator p = sections.begin();
292 Output_section* os = *p;
293 uint64_t address = os->is_address_valid() ? os->address() : 0;
294 off_t data_size = os->is_data_size_valid() ? os->data_size() : -1;
295 off_t offset = os->is_offset_valid()? os->offset() : -1 ;
297 if (i >= this->section_infos_.size())
299 gold_fatal("Section_info of %s missing.\n", os->name());
301 const Section_info& info = this->section_infos_[i];
302 if (os != info.output_section)
303 gold_fatal("Section order changed. Expecting %s but see %s\n",
304 info.output_section->name(), os->name());
305 if (address != info.address
306 || data_size != info.data_size
307 || offset != info.offset)
308 gold_fatal("Section %s changed.\n", os->name());
312 // Layout_task_runner methods.
314 // Lay out the sections. This is called after all the input objects
318 Layout_task_runner::run(Workqueue* workqueue, const Task* task)
320 Layout* layout = this->layout_;
321 off_t file_size = layout->finalize(this->input_objects_,
326 // Now we know the final size of the output file and we know where
327 // each piece of information goes.
329 if (this->mapfile_ != NULL)
331 this->mapfile_->print_discarded_sections(this->input_objects_);
332 layout->print_to_mapfile(this->mapfile_);
336 if (layout->incremental_base() == NULL)
338 of = new Output_file(parameters->options().output_file_name());
339 if (this->options_.oformat_enum() != General_options::OBJECT_FORMAT_ELF)
340 of->set_is_temporary();
345 of = layout->incremental_base()->output_file();
347 // Apply the incremental relocations for symbols whose values
348 // have changed. We do this before we resize the file and start
349 // writing anything else to it, so that we can read the old
350 // incremental information from the file before (possibly)
352 if (parameters->incremental_update())
353 layout->incremental_base()->apply_incremental_relocs(this->symtab_,
357 of->resize(file_size);
360 // Queue up the final set of tasks.
361 gold::queue_final_tasks(this->options_, this->input_objects_,
362 this->symtab_, layout, workqueue, of);
367 Layout::Layout(int number_of_input_files, Script_options* script_options)
368 : number_of_input_files_(number_of_input_files),
369 script_options_(script_options),
377 unattached_section_list_(),
378 special_output_list_(),
379 section_headers_(NULL),
381 relro_segment_(NULL),
382 interp_segment_(NULL),
384 symtab_section_(NULL),
385 symtab_xindex_(NULL),
386 dynsym_section_(NULL),
387 dynsym_xindex_(NULL),
388 dynamic_section_(NULL),
389 dynamic_symbol_(NULL),
391 eh_frame_section_(NULL),
392 eh_frame_data_(NULL),
393 added_eh_frame_data_(false),
394 eh_frame_hdr_section_(NULL),
395 gdb_index_data_(NULL),
396 build_id_note_(NULL),
400 output_file_size_(-1),
401 have_added_input_section_(false),
402 sections_are_attached_(false),
403 input_requires_executable_stack_(false),
404 input_with_gnu_stack_note_(false),
405 input_without_gnu_stack_note_(false),
406 has_static_tls_(false),
407 any_postprocessing_sections_(false),
408 resized_signatures_(false),
409 have_stabstr_section_(false),
410 section_ordering_specified_(false),
411 incremental_inputs_(NULL),
412 record_output_section_data_from_script_(false),
413 script_output_section_data_list_(),
414 segment_states_(NULL),
415 relaxation_debug_check_(NULL),
416 section_order_map_(),
417 input_section_position_(),
418 input_section_glob_(),
419 incremental_base_(NULL),
422 // Make space for more than enough segments for a typical file.
423 // This is just for efficiency--it's OK if we wind up needing more.
424 this->segment_list_.reserve(12);
426 // We expect two unattached Output_data objects: the file header and
427 // the segment headers.
428 this->special_output_list_.reserve(2);
430 // Initialize structure needed for an incremental build.
431 if (parameters->incremental())
432 this->incremental_inputs_ = new Incremental_inputs;
434 // The section name pool is worth optimizing in all cases, because
435 // it is small, but there are often overlaps due to .rel sections.
436 this->namepool_.set_optimize();
439 // For incremental links, record the base file to be modified.
442 Layout::set_incremental_base(Incremental_binary* base)
444 this->incremental_base_ = base;
445 this->free_list_.init(base->output_file()->filesize(), true);
448 // Hash a key we use to look up an output section mapping.
451 Layout::Hash_key::operator()(const Layout::Key& k) const
453 return k.first + k.second.first + k.second.second;
456 // Returns whether the given section is in the list of
457 // debug-sections-used-by-some-version-of-gdb. Currently,
458 // we've checked versions of gdb up to and including 7.4.
460 static const char* gdb_sections[] =
462 ".debug_addr", // Fission extension
463 // ".debug_aranges", // not used by gdb as of 7.4
470 // ".debug_pubnames", // not used by gdb as of 7.4
471 // ".debug_pubtypes", // not used by gdb as of 7.4
476 static const char* lines_only_debug_sections[] =
478 // ".debug_addr", // Fission extension
479 // ".debug_aranges", // not used by gdb as of 7.4
486 // ".debug_pubnames", // not used by gdb as of 7.4
487 // ".debug_pubtypes", // not used by gdb as of 7.4
493 is_gdb_debug_section(const char* str)
495 // We can do this faster: binary search or a hashtable. But why bother?
496 for (size_t i = 0; i < sizeof(gdb_sections)/sizeof(*gdb_sections); ++i)
497 if (strcmp(str, gdb_sections[i]) == 0)
503 is_lines_only_debug_section(const char* str)
505 // We can do this faster: binary search or a hashtable. But why bother?
507 i < sizeof(lines_only_debug_sections)/sizeof(*lines_only_debug_sections);
509 if (strcmp(str, lines_only_debug_sections[i]) == 0)
514 // Sometimes we compress sections. This is typically done for
515 // sections that are not part of normal program execution (such as
516 // .debug_* sections), and where the readers of these sections know
517 // how to deal with compressed sections. This routine doesn't say for
518 // certain whether we'll compress -- it depends on commandline options
519 // as well -- just whether this section is a candidate for compression.
520 // (The Output_compressed_section class decides whether to compress
521 // a given section, and picks the name of the compressed section.)
524 is_compressible_debug_section(const char* secname)
526 return (is_prefix_of(".debug", secname));
529 // We may see compressed debug sections in input files. Return TRUE
530 // if this is the name of a compressed debug section.
533 is_compressed_debug_section(const char* secname)
535 return (is_prefix_of(".zdebug", secname));
538 // Whether to include this section in the link.
540 template<int size, bool big_endian>
542 Layout::include_section(Sized_relobj_file<size, big_endian>*, const char* name,
543 const elfcpp::Shdr<size, big_endian>& shdr)
545 if (shdr.get_sh_flags() & elfcpp::SHF_EXCLUDE)
548 switch (shdr.get_sh_type())
550 case elfcpp::SHT_NULL:
551 case elfcpp::SHT_SYMTAB:
552 case elfcpp::SHT_DYNSYM:
553 case elfcpp::SHT_HASH:
554 case elfcpp::SHT_DYNAMIC:
555 case elfcpp::SHT_SYMTAB_SHNDX:
558 case elfcpp::SHT_STRTAB:
559 // Discard the sections which have special meanings in the ELF
560 // ABI. Keep others (e.g., .stabstr). We could also do this by
561 // checking the sh_link fields of the appropriate sections.
562 return (strcmp(name, ".dynstr") != 0
563 && strcmp(name, ".strtab") != 0
564 && strcmp(name, ".shstrtab") != 0);
566 case elfcpp::SHT_RELA:
567 case elfcpp::SHT_REL:
568 case elfcpp::SHT_GROUP:
569 // If we are emitting relocations these should be handled
571 gold_assert(!parameters->options().relocatable()
572 && !parameters->options().emit_relocs());
575 case elfcpp::SHT_PROGBITS:
576 if (parameters->options().strip_debug()
577 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
579 if (is_debug_info_section(name))
582 if (parameters->options().strip_debug_non_line()
583 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
585 // Debugging sections can only be recognized by name.
586 if (is_prefix_of(".debug", name)
587 && !is_lines_only_debug_section(name))
590 if (parameters->options().strip_debug_gdb()
591 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
593 // Debugging sections can only be recognized by name.
594 if (is_prefix_of(".debug", name)
595 && !is_gdb_debug_section(name))
598 if (parameters->options().strip_lto_sections()
599 && !parameters->options().relocatable()
600 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
602 // Ignore LTO sections containing intermediate code.
603 if (is_prefix_of(".gnu.lto_", name))
606 // The GNU linker strips .gnu_debuglink sections, so we do too.
607 // This is a feature used to keep debugging information in
609 if (strcmp(name, ".gnu_debuglink") == 0)
618 // Return an output section named NAME, or NULL if there is none.
621 Layout::find_output_section(const char* name) const
623 for (Section_list::const_iterator p = this->section_list_.begin();
624 p != this->section_list_.end();
626 if (strcmp((*p)->name(), name) == 0)
631 // Return an output segment of type TYPE, with segment flags SET set
632 // and segment flags CLEAR clear. Return NULL if there is none.
635 Layout::find_output_segment(elfcpp::PT type, elfcpp::Elf_Word set,
636 elfcpp::Elf_Word clear) const
638 for (Segment_list::const_iterator p = this->segment_list_.begin();
639 p != this->segment_list_.end();
641 if (static_cast<elfcpp::PT>((*p)->type()) == type
642 && ((*p)->flags() & set) == set
643 && ((*p)->flags() & clear) == 0)
648 // When we put a .ctors or .dtors section with more than one word into
649 // a .init_array or .fini_array section, we need to reverse the words
650 // in the .ctors/.dtors section. This is because .init_array executes
651 // constructors front to back, where .ctors executes them back to
652 // front, and vice-versa for .fini_array/.dtors. Although we do want
653 // to remap .ctors/.dtors into .init_array/.fini_array because it can
654 // be more efficient, we don't want to change the order in which
655 // constructors/destructors are run. This set just keeps track of
656 // these sections which need to be reversed. It is only changed by
657 // Layout::layout. It should be a private member of Layout, but that
658 // would require layout.h to #include object.h to get the definition
660 static Unordered_set<Section_id, Section_id_hash> ctors_sections_in_init_array;
662 // Return whether OBJECT/SHNDX is a .ctors/.dtors section mapped to a
663 // .init_array/.fini_array section.
666 Layout::is_ctors_in_init_array(Relobj* relobj, unsigned int shndx) const
668 return (ctors_sections_in_init_array.find(Section_id(relobj, shndx))
669 != ctors_sections_in_init_array.end());
672 // Return the output section to use for section NAME with type TYPE
673 // and section flags FLAGS. NAME must be canonicalized in the string
674 // pool, and NAME_KEY is the key. ORDER is where this should appear
675 // in the output sections. IS_RELRO is true for a relro section.
678 Layout::get_output_section(const char* name, Stringpool::Key name_key,
679 elfcpp::Elf_Word type, elfcpp::Elf_Xword flags,
680 Output_section_order order, bool is_relro)
682 elfcpp::Elf_Word lookup_type = type;
684 // For lookup purposes, treat INIT_ARRAY, FINI_ARRAY, and
685 // PREINIT_ARRAY like PROGBITS. This ensures that we combine
686 // .init_array, .fini_array, and .preinit_array sections by name
687 // whatever their type in the input file. We do this because the
688 // types are not always right in the input files.
689 if (lookup_type == elfcpp::SHT_INIT_ARRAY
690 || lookup_type == elfcpp::SHT_FINI_ARRAY
691 || lookup_type == elfcpp::SHT_PREINIT_ARRAY)
692 lookup_type = elfcpp::SHT_PROGBITS;
694 elfcpp::Elf_Xword lookup_flags = flags;
696 // Ignoring SHF_WRITE and SHF_EXECINSTR here means that we combine
697 // read-write with read-only sections. Some other ELF linkers do
698 // not do this. FIXME: Perhaps there should be an option
700 lookup_flags &= ~(elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR);
702 const Key key(name_key, std::make_pair(lookup_type, lookup_flags));
703 const std::pair<Key, Output_section*> v(key, NULL);
704 std::pair<Section_name_map::iterator, bool> ins(
705 this->section_name_map_.insert(v));
708 return ins.first->second;
711 // This is the first time we've seen this name/type/flags
712 // combination. For compatibility with the GNU linker, we
713 // combine sections with contents and zero flags with sections
714 // with non-zero flags. This is a workaround for cases where
715 // assembler code forgets to set section flags. FIXME: Perhaps
716 // there should be an option to control this.
717 Output_section* os = NULL;
719 if (lookup_type == elfcpp::SHT_PROGBITS)
723 Output_section* same_name = this->find_output_section(name);
724 if (same_name != NULL
725 && (same_name->type() == elfcpp::SHT_PROGBITS
726 || same_name->type() == elfcpp::SHT_INIT_ARRAY
727 || same_name->type() == elfcpp::SHT_FINI_ARRAY
728 || same_name->type() == elfcpp::SHT_PREINIT_ARRAY)
729 && (same_name->flags() & elfcpp::SHF_TLS) == 0)
732 else if ((flags & elfcpp::SHF_TLS) == 0)
734 elfcpp::Elf_Xword zero_flags = 0;
735 const Key zero_key(name_key, std::make_pair(lookup_type,
737 Section_name_map::iterator p =
738 this->section_name_map_.find(zero_key);
739 if (p != this->section_name_map_.end())
745 os = this->make_output_section(name, type, flags, order, is_relro);
747 ins.first->second = os;
752 // Pick the output section to use for section NAME, in input file
753 // RELOBJ, with type TYPE and flags FLAGS. RELOBJ may be NULL for a
754 // linker created section. IS_INPUT_SECTION is true if we are
755 // choosing an output section for an input section found in a input
756 // file. ORDER is where this section should appear in the output
757 // sections. IS_RELRO is true for a relro section. This will return
758 // NULL if the input section should be discarded.
761 Layout::choose_output_section(const Relobj* relobj, const char* name,
762 elfcpp::Elf_Word type, elfcpp::Elf_Xword flags,
763 bool is_input_section, Output_section_order order,
766 // We should not see any input sections after we have attached
767 // sections to segments.
768 gold_assert(!is_input_section || !this->sections_are_attached_);
770 // Some flags in the input section should not be automatically
771 // copied to the output section.
772 flags &= ~ (elfcpp::SHF_INFO_LINK
775 | elfcpp::SHF_STRINGS);
777 // We only clear the SHF_LINK_ORDER flag in for
778 // a non-relocatable link.
779 if (!parameters->options().relocatable())
780 flags &= ~elfcpp::SHF_LINK_ORDER;
782 if (this->script_options_->saw_sections_clause())
784 // We are using a SECTIONS clause, so the output section is
785 // chosen based only on the name.
787 Script_sections* ss = this->script_options_->script_sections();
788 const char* file_name = relobj == NULL ? NULL : relobj->name().c_str();
789 Output_section** output_section_slot;
790 Script_sections::Section_type script_section_type;
791 const char* orig_name = name;
792 name = ss->output_section_name(file_name, name, &output_section_slot,
793 &script_section_type);
796 gold_debug(DEBUG_SCRIPT, _("Unable to create output section '%s' "
797 "because it is not allowed by the "
798 "SECTIONS clause of the linker script"),
800 // The SECTIONS clause says to discard this input section.
804 // We can only handle script section types ST_NONE and ST_NOLOAD.
805 switch (script_section_type)
807 case Script_sections::ST_NONE:
809 case Script_sections::ST_NOLOAD:
810 flags &= elfcpp::SHF_ALLOC;
816 // If this is an orphan section--one not mentioned in the linker
817 // script--then OUTPUT_SECTION_SLOT will be NULL, and we do the
818 // default processing below.
820 if (output_section_slot != NULL)
822 if (*output_section_slot != NULL)
824 (*output_section_slot)->update_flags_for_input_section(flags);
825 return *output_section_slot;
828 // We don't put sections found in the linker script into
829 // SECTION_NAME_MAP_. That keeps us from getting confused
830 // if an orphan section is mapped to a section with the same
831 // name as one in the linker script.
833 name = this->namepool_.add(name, false, NULL);
835 Output_section* os = this->make_output_section(name, type, flags,
838 os->set_found_in_sections_clause();
840 // Special handling for NOLOAD sections.
841 if (script_section_type == Script_sections::ST_NOLOAD)
845 // The constructor of Output_section sets addresses of non-ALLOC
846 // sections to 0 by default. We don't want that for NOLOAD
847 // sections even if they have no SHF_ALLOC flag.
848 if ((os->flags() & elfcpp::SHF_ALLOC) == 0
849 && os->is_address_valid())
851 gold_assert(os->address() == 0
852 && !os->is_offset_valid()
853 && !os->is_data_size_valid());
854 os->reset_address_and_file_offset();
858 *output_section_slot = os;
863 // FIXME: Handle SHF_OS_NONCONFORMING somewhere.
865 size_t len = strlen(name);
866 char* uncompressed_name = NULL;
868 // Compressed debug sections should be mapped to the corresponding
869 // uncompressed section.
870 if (is_compressed_debug_section(name))
872 uncompressed_name = new char[len];
873 uncompressed_name[0] = '.';
874 gold_assert(name[0] == '.' && name[1] == 'z');
875 strncpy(&uncompressed_name[1], &name[2], len - 2);
876 uncompressed_name[len - 1] = '\0';
878 name = uncompressed_name;
881 // Turn NAME from the name of the input section into the name of the
884 && !this->script_options_->saw_sections_clause()
885 && !parameters->options().relocatable())
886 name = Layout::output_section_name(relobj, name, &len);
888 Stringpool::Key name_key;
889 name = this->namepool_.add_with_length(name, len, true, &name_key);
891 if (uncompressed_name != NULL)
892 delete[] uncompressed_name;
894 // Find or make the output section. The output section is selected
895 // based on the section name, type, and flags.
896 return this->get_output_section(name, name_key, type, flags, order, is_relro);
899 // For incremental links, record the initial fixed layout of a section
900 // from the base file, and return a pointer to the Output_section.
902 template<int size, bool big_endian>
904 Layout::init_fixed_output_section(const char* name,
905 elfcpp::Shdr<size, big_endian>& shdr)
907 unsigned int sh_type = shdr.get_sh_type();
909 // We preserve the layout of PROGBITS, NOBITS, INIT_ARRAY, FINI_ARRAY,
910 // PRE_INIT_ARRAY, and NOTE sections.
911 // All others will be created from scratch and reallocated.
912 if (!can_incremental_update(sh_type))
915 // If we're generating a .gdb_index section, we need to regenerate
917 if (parameters->options().gdb_index()
918 && sh_type == elfcpp::SHT_PROGBITS
919 && strcmp(name, ".gdb_index") == 0)
922 typename elfcpp::Elf_types<size>::Elf_Addr sh_addr = shdr.get_sh_addr();
923 typename elfcpp::Elf_types<size>::Elf_Off sh_offset = shdr.get_sh_offset();
924 typename elfcpp::Elf_types<size>::Elf_WXword sh_size = shdr.get_sh_size();
925 typename elfcpp::Elf_types<size>::Elf_WXword sh_flags = shdr.get_sh_flags();
926 typename elfcpp::Elf_types<size>::Elf_WXword sh_addralign =
927 shdr.get_sh_addralign();
929 // Make the output section.
930 Stringpool::Key name_key;
931 name = this->namepool_.add(name, true, &name_key);
932 Output_section* os = this->get_output_section(name, name_key, sh_type,
933 sh_flags, ORDER_INVALID, false);
934 os->set_fixed_layout(sh_addr, sh_offset, sh_size, sh_addralign);
935 if (sh_type != elfcpp::SHT_NOBITS)
936 this->free_list_.remove(sh_offset, sh_offset + sh_size);
940 // Return the output section to use for input section SHNDX, with name
941 // NAME, with header HEADER, from object OBJECT. RELOC_SHNDX is the
942 // index of a relocation section which applies to this section, or 0
943 // if none, or -1U if more than one. RELOC_TYPE is the type of the
944 // relocation section if there is one. Set *OFF to the offset of this
945 // input section without the output section. Return NULL if the
946 // section should be discarded. Set *OFF to -1 if the section
947 // contents should not be written directly to the output file, but
948 // will instead receive special handling.
950 template<int size, bool big_endian>
952 Layout::layout(Sized_relobj_file<size, big_endian>* object, unsigned int shndx,
953 const char* name, const elfcpp::Shdr<size, big_endian>& shdr,
954 unsigned int reloc_shndx, unsigned int, off_t* off)
958 if (!this->include_section(object, name, shdr))
961 elfcpp::Elf_Word sh_type = shdr.get_sh_type();
963 // In a relocatable link a grouped section must not be combined with
964 // any other sections.
966 if (parameters->options().relocatable()
967 && (shdr.get_sh_flags() & elfcpp::SHF_GROUP) != 0)
969 name = this->namepool_.add(name, true, NULL);
970 os = this->make_output_section(name, sh_type, shdr.get_sh_flags(),
971 ORDER_INVALID, false);
975 os = this->choose_output_section(object, name, sh_type,
976 shdr.get_sh_flags(), true,
977 ORDER_INVALID, false);
982 // By default the GNU linker sorts input sections whose names match
983 // .ctors.*, .dtors.*, .init_array.*, or .fini_array.*. The
984 // sections are sorted by name. This is used to implement
985 // constructor priority ordering. We are compatible. When we put
986 // .ctor sections in .init_array and .dtor sections in .fini_array,
987 // we must also sort plain .ctor and .dtor sections.
988 if (!this->script_options_->saw_sections_clause()
989 && !parameters->options().relocatable()
990 && (is_prefix_of(".ctors.", name)
991 || is_prefix_of(".dtors.", name)
992 || is_prefix_of(".init_array.", name)
993 || is_prefix_of(".fini_array.", name)
994 || (parameters->options().ctors_in_init_array()
995 && (strcmp(name, ".ctors") == 0
996 || strcmp(name, ".dtors") == 0))))
997 os->set_must_sort_attached_input_sections();
999 // If this is a .ctors or .ctors.* section being mapped to a
1000 // .init_array section, or a .dtors or .dtors.* section being mapped
1001 // to a .fini_array section, we will need to reverse the words if
1002 // there is more than one. Record this section for later. See
1003 // ctors_sections_in_init_array above.
1004 if (!this->script_options_->saw_sections_clause()
1005 && !parameters->options().relocatable()
1006 && shdr.get_sh_size() > size / 8
1007 && (((strcmp(name, ".ctors") == 0
1008 || is_prefix_of(".ctors.", name))
1009 && strcmp(os->name(), ".init_array") == 0)
1010 || ((strcmp(name, ".dtors") == 0
1011 || is_prefix_of(".dtors.", name))
1012 && strcmp(os->name(), ".fini_array") == 0)))
1013 ctors_sections_in_init_array.insert(Section_id(object, shndx));
1015 // FIXME: Handle SHF_LINK_ORDER somewhere.
1017 elfcpp::Elf_Xword orig_flags = os->flags();
1019 *off = os->add_input_section(this, object, shndx, name, shdr, reloc_shndx,
1020 this->script_options_->saw_sections_clause());
1022 // If the flags changed, we may have to change the order.
1023 if ((orig_flags & elfcpp::SHF_ALLOC) != 0)
1025 orig_flags &= (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR);
1026 elfcpp::Elf_Xword new_flags =
1027 os->flags() & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR);
1028 if (orig_flags != new_flags)
1029 os->set_order(this->default_section_order(os, false));
1032 this->have_added_input_section_ = true;
1037 // Handle a relocation section when doing a relocatable link.
1039 template<int size, bool big_endian>
1041 Layout::layout_reloc(Sized_relobj_file<size, big_endian>* object,
1043 const elfcpp::Shdr<size, big_endian>& shdr,
1044 Output_section* data_section,
1045 Relocatable_relocs* rr)
1047 gold_assert(parameters->options().relocatable()
1048 || parameters->options().emit_relocs());
1050 int sh_type = shdr.get_sh_type();
1053 if (sh_type == elfcpp::SHT_REL)
1055 else if (sh_type == elfcpp::SHT_RELA)
1059 name += data_section->name();
1061 // In a relocatable link relocs for a grouped section must not be
1062 // combined with other reloc sections.
1064 if (!parameters->options().relocatable()
1065 || (data_section->flags() & elfcpp::SHF_GROUP) == 0)
1066 os = this->choose_output_section(object, name.c_str(), sh_type,
1067 shdr.get_sh_flags(), false,
1068 ORDER_INVALID, false);
1071 const char* n = this->namepool_.add(name.c_str(), true, NULL);
1072 os = this->make_output_section(n, sh_type, shdr.get_sh_flags(),
1073 ORDER_INVALID, false);
1076 os->set_should_link_to_symtab();
1077 os->set_info_section(data_section);
1079 Output_section_data* posd;
1080 if (sh_type == elfcpp::SHT_REL)
1082 os->set_entsize(elfcpp::Elf_sizes<size>::rel_size);
1083 posd = new Output_relocatable_relocs<elfcpp::SHT_REL,
1087 else if (sh_type == elfcpp::SHT_RELA)
1089 os->set_entsize(elfcpp::Elf_sizes<size>::rela_size);
1090 posd = new Output_relocatable_relocs<elfcpp::SHT_RELA,
1097 os->add_output_section_data(posd);
1098 rr->set_output_data(posd);
1103 // Handle a group section when doing a relocatable link.
1105 template<int size, bool big_endian>
1107 Layout::layout_group(Symbol_table* symtab,
1108 Sized_relobj_file<size, big_endian>* object,
1110 const char* group_section_name,
1111 const char* signature,
1112 const elfcpp::Shdr<size, big_endian>& shdr,
1113 elfcpp::Elf_Word flags,
1114 std::vector<unsigned int>* shndxes)
1116 gold_assert(parameters->options().relocatable());
1117 gold_assert(shdr.get_sh_type() == elfcpp::SHT_GROUP);
1118 group_section_name = this->namepool_.add(group_section_name, true, NULL);
1119 Output_section* os = this->make_output_section(group_section_name,
1121 shdr.get_sh_flags(),
1122 ORDER_INVALID, false);
1124 // We need to find a symbol with the signature in the symbol table.
1125 // If we don't find one now, we need to look again later.
1126 Symbol* sym = symtab->lookup(signature, NULL);
1128 os->set_info_symndx(sym);
1131 // Reserve some space to minimize reallocations.
1132 if (this->group_signatures_.empty())
1133 this->group_signatures_.reserve(this->number_of_input_files_ * 16);
1135 // We will wind up using a symbol whose name is the signature.
1136 // So just put the signature in the symbol name pool to save it.
1137 signature = symtab->canonicalize_name(signature);
1138 this->group_signatures_.push_back(Group_signature(os, signature));
1141 os->set_should_link_to_symtab();
1144 section_size_type entry_count =
1145 convert_to_section_size_type(shdr.get_sh_size() / 4);
1146 Output_section_data* posd =
1147 new Output_data_group<size, big_endian>(object, entry_count, flags,
1149 os->add_output_section_data(posd);
1152 // Special GNU handling of sections name .eh_frame. They will
1153 // normally hold exception frame data as defined by the C++ ABI
1154 // (http://codesourcery.com/cxx-abi/).
1156 template<int size, bool big_endian>
1158 Layout::layout_eh_frame(Sized_relobj_file<size, big_endian>* object,
1159 const unsigned char* symbols,
1161 const unsigned char* symbol_names,
1162 off_t symbol_names_size,
1164 const elfcpp::Shdr<size, big_endian>& shdr,
1165 unsigned int reloc_shndx, unsigned int reloc_type,
1168 gold_assert(shdr.get_sh_type() == elfcpp::SHT_PROGBITS
1169 || shdr.get_sh_type() == elfcpp::SHT_X86_64_UNWIND);
1170 gold_assert((shdr.get_sh_flags() & elfcpp::SHF_ALLOC) != 0);
1172 Output_section* os = this->make_eh_frame_section(object);
1176 gold_assert(this->eh_frame_section_ == os);
1178 elfcpp::Elf_Xword orig_flags = os->flags();
1180 if (!parameters->incremental()
1181 && this->eh_frame_data_->add_ehframe_input_section(object,
1190 os->update_flags_for_input_section(shdr.get_sh_flags());
1192 // A writable .eh_frame section is a RELRO section.
1193 if ((orig_flags & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR))
1194 != (os->flags() & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR)))
1197 os->set_order(ORDER_RELRO);
1200 // We found a .eh_frame section we are going to optimize, so now
1201 // we can add the set of optimized sections to the output
1202 // section. We need to postpone adding this until we've found a
1203 // section we can optimize so that the .eh_frame section in
1204 // crtbegin.o winds up at the start of the output section.
1205 if (!this->added_eh_frame_data_)
1207 os->add_output_section_data(this->eh_frame_data_);
1208 this->added_eh_frame_data_ = true;
1214 // We couldn't handle this .eh_frame section for some reason.
1215 // Add it as a normal section.
1216 bool saw_sections_clause = this->script_options_->saw_sections_clause();
1217 *off = os->add_input_section(this, object, shndx, ".eh_frame", shdr,
1218 reloc_shndx, saw_sections_clause);
1219 this->have_added_input_section_ = true;
1221 if ((orig_flags & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR))
1222 != (os->flags() & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR)))
1223 os->set_order(this->default_section_order(os, false));
1229 // Create and return the magic .eh_frame section. Create
1230 // .eh_frame_hdr also if appropriate. OBJECT is the object with the
1231 // input .eh_frame section; it may be NULL.
1234 Layout::make_eh_frame_section(const Relobj* object)
1236 // FIXME: On x86_64, this could use SHT_X86_64_UNWIND rather than
1238 Output_section* os = this->choose_output_section(object, ".eh_frame",
1239 elfcpp::SHT_PROGBITS,
1240 elfcpp::SHF_ALLOC, false,
1241 ORDER_EHFRAME, false);
1245 if (this->eh_frame_section_ == NULL)
1247 this->eh_frame_section_ = os;
1248 this->eh_frame_data_ = new Eh_frame();
1250 // For incremental linking, we do not optimize .eh_frame sections
1251 // or create a .eh_frame_hdr section.
1252 if (parameters->options().eh_frame_hdr() && !parameters->incremental())
1254 Output_section* hdr_os =
1255 this->choose_output_section(NULL, ".eh_frame_hdr",
1256 elfcpp::SHT_PROGBITS,
1257 elfcpp::SHF_ALLOC, false,
1258 ORDER_EHFRAME, false);
1262 Eh_frame_hdr* hdr_posd = new Eh_frame_hdr(os,
1263 this->eh_frame_data_);
1264 hdr_os->add_output_section_data(hdr_posd);
1266 hdr_os->set_after_input_sections();
1268 if (!this->script_options_->saw_phdrs_clause())
1270 Output_segment* hdr_oseg;
1271 hdr_oseg = this->make_output_segment(elfcpp::PT_GNU_EH_FRAME,
1273 hdr_oseg->add_output_section_to_nonload(hdr_os,
1277 this->eh_frame_data_->set_eh_frame_hdr(hdr_posd);
1285 // Add an exception frame for a PLT. This is called from target code.
1288 Layout::add_eh_frame_for_plt(Output_data* plt, const unsigned char* cie_data,
1289 size_t cie_length, const unsigned char* fde_data,
1292 if (parameters->incremental())
1294 // FIXME: Maybe this could work some day....
1297 Output_section* os = this->make_eh_frame_section(NULL);
1300 this->eh_frame_data_->add_ehframe_for_plt(plt, cie_data, cie_length,
1301 fde_data, fde_length);
1302 if (!this->added_eh_frame_data_)
1304 os->add_output_section_data(this->eh_frame_data_);
1305 this->added_eh_frame_data_ = true;
1309 // Scan a .debug_info or .debug_types section, and add summary
1310 // information to the .gdb_index section.
1312 template<int size, bool big_endian>
1314 Layout::add_to_gdb_index(bool is_type_unit,
1315 Sized_relobj<size, big_endian>* object,
1316 const unsigned char* symbols,
1319 unsigned int reloc_shndx,
1320 unsigned int reloc_type)
1322 if (this->gdb_index_data_ == NULL)
1324 Output_section* os = this->choose_output_section(NULL, ".gdb_index",
1325 elfcpp::SHT_PROGBITS, 0,
1326 false, ORDER_INVALID,
1331 this->gdb_index_data_ = new Gdb_index(os);
1332 os->add_output_section_data(this->gdb_index_data_);
1333 os->set_after_input_sections();
1336 this->gdb_index_data_->scan_debug_info(is_type_unit, object, symbols,
1337 symbols_size, shndx, reloc_shndx,
1341 // Add POSD to an output section using NAME, TYPE, and FLAGS. Return
1342 // the output section.
1345 Layout::add_output_section_data(const char* name, elfcpp::Elf_Word type,
1346 elfcpp::Elf_Xword flags,
1347 Output_section_data* posd,
1348 Output_section_order order, bool is_relro)
1350 Output_section* os = this->choose_output_section(NULL, name, type, flags,
1351 false, order, is_relro);
1353 os->add_output_section_data(posd);
1357 // Map section flags to segment flags.
1360 Layout::section_flags_to_segment(elfcpp::Elf_Xword flags)
1362 elfcpp::Elf_Word ret = elfcpp::PF_R;
1363 if ((flags & elfcpp::SHF_WRITE) != 0)
1364 ret |= elfcpp::PF_W;
1365 if ((flags & elfcpp::SHF_EXECINSTR) != 0)
1366 ret |= elfcpp::PF_X;
1370 // Make a new Output_section, and attach it to segments as
1371 // appropriate. ORDER is the order in which this section should
1372 // appear in the output segment. IS_RELRO is true if this is a relro
1373 // (read-only after relocations) section.
1376 Layout::make_output_section(const char* name, elfcpp::Elf_Word type,
1377 elfcpp::Elf_Xword flags,
1378 Output_section_order order, bool is_relro)
1381 if ((flags & elfcpp::SHF_ALLOC) == 0
1382 && strcmp(parameters->options().compress_debug_sections(), "none") != 0
1383 && is_compressible_debug_section(name))
1384 os = new Output_compressed_section(¶meters->options(), name, type,
1386 else if ((flags & elfcpp::SHF_ALLOC) == 0
1387 && parameters->options().strip_debug_non_line()
1388 && strcmp(".debug_abbrev", name) == 0)
1390 os = this->debug_abbrev_ = new Output_reduced_debug_abbrev_section(
1392 if (this->debug_info_)
1393 this->debug_info_->set_abbreviations(this->debug_abbrev_);
1395 else if ((flags & elfcpp::SHF_ALLOC) == 0
1396 && parameters->options().strip_debug_non_line()
1397 && strcmp(".debug_info", name) == 0)
1399 os = this->debug_info_ = new Output_reduced_debug_info_section(
1401 if (this->debug_abbrev_)
1402 this->debug_info_->set_abbreviations(this->debug_abbrev_);
1406 // Sometimes .init_array*, .preinit_array* and .fini_array* do
1407 // not have correct section types. Force them here.
1408 if (type == elfcpp::SHT_PROGBITS)
1410 if (is_prefix_of(".init_array", name))
1411 type = elfcpp::SHT_INIT_ARRAY;
1412 else if (is_prefix_of(".preinit_array", name))
1413 type = elfcpp::SHT_PREINIT_ARRAY;
1414 else if (is_prefix_of(".fini_array", name))
1415 type = elfcpp::SHT_FINI_ARRAY;
1418 // FIXME: const_cast is ugly.
1419 Target* target = const_cast<Target*>(¶meters->target());
1420 os = target->make_output_section(name, type, flags);
1423 // With -z relro, we have to recognize the special sections by name.
1424 // There is no other way.
1425 bool is_relro_local = false;
1426 if (!this->script_options_->saw_sections_clause()
1427 && parameters->options().relro()
1428 && (flags & elfcpp::SHF_ALLOC) != 0
1429 && (flags & elfcpp::SHF_WRITE) != 0)
1431 if (type == elfcpp::SHT_PROGBITS)
1433 if ((flags & elfcpp::SHF_TLS) != 0)
1435 else if (strcmp(name, ".data.rel.ro") == 0)
1437 else if (strcmp(name, ".data.rel.ro.local") == 0)
1440 is_relro_local = true;
1442 else if (strcmp(name, ".ctors") == 0
1443 || strcmp(name, ".dtors") == 0
1444 || strcmp(name, ".jcr") == 0)
1447 else if (type == elfcpp::SHT_INIT_ARRAY
1448 || type == elfcpp::SHT_FINI_ARRAY
1449 || type == elfcpp::SHT_PREINIT_ARRAY)
1456 if (order == ORDER_INVALID && (flags & elfcpp::SHF_ALLOC) != 0)
1457 order = this->default_section_order(os, is_relro_local);
1459 os->set_order(order);
1461 parameters->target().new_output_section(os);
1463 this->section_list_.push_back(os);
1465 // The GNU linker by default sorts some sections by priority, so we
1466 // do the same. We need to know that this might happen before we
1467 // attach any input sections.
1468 if (!this->script_options_->saw_sections_clause()
1469 && !parameters->options().relocatable()
1470 && (strcmp(name, ".init_array") == 0
1471 || strcmp(name, ".fini_array") == 0
1472 || (!parameters->options().ctors_in_init_array()
1473 && (strcmp(name, ".ctors") == 0
1474 || strcmp(name, ".dtors") == 0))))
1475 os->set_may_sort_attached_input_sections();
1477 // Check for .stab*str sections, as .stab* sections need to link to
1479 if (type == elfcpp::SHT_STRTAB
1480 && !this->have_stabstr_section_
1481 && strncmp(name, ".stab", 5) == 0
1482 && strcmp(name + strlen(name) - 3, "str") == 0)
1483 this->have_stabstr_section_ = true;
1485 // During a full incremental link, we add patch space to most
1486 // PROGBITS and NOBITS sections. Flag those that may be
1487 // arbitrarily padded.
1488 if ((type == elfcpp::SHT_PROGBITS || type == elfcpp::SHT_NOBITS)
1489 && order != ORDER_INTERP
1490 && order != ORDER_INIT
1491 && order != ORDER_PLT
1492 && order != ORDER_FINI
1493 && order != ORDER_RELRO_LAST
1494 && order != ORDER_NON_RELRO_FIRST
1495 && strcmp(name, ".eh_frame") != 0
1496 && strcmp(name, ".ctors") != 0
1497 && strcmp(name, ".dtors") != 0
1498 && strcmp(name, ".jcr") != 0)
1500 os->set_is_patch_space_allowed();
1502 // Certain sections require "holes" to be filled with
1503 // specific fill patterns. These fill patterns may have
1504 // a minimum size, so we must prevent allocations from the
1505 // free list that leave a hole smaller than the minimum.
1506 if (strcmp(name, ".debug_info") == 0)
1507 os->set_free_space_fill(new Output_fill_debug_info(false));
1508 else if (strcmp(name, ".debug_types") == 0)
1509 os->set_free_space_fill(new Output_fill_debug_info(true));
1510 else if (strcmp(name, ".debug_line") == 0)
1511 os->set_free_space_fill(new Output_fill_debug_line());
1514 // If we have already attached the sections to segments, then we
1515 // need to attach this one now. This happens for sections created
1516 // directly by the linker.
1517 if (this->sections_are_attached_)
1518 this->attach_section_to_segment(¶meters->target(), os);
1523 // Return the default order in which a section should be placed in an
1524 // output segment. This function captures a lot of the ideas in
1525 // ld/scripttempl/elf.sc in the GNU linker. Note that the order of a
1526 // linker created section is normally set when the section is created;
1527 // this function is used for input sections.
1529 Output_section_order
1530 Layout::default_section_order(Output_section* os, bool is_relro_local)
1532 gold_assert((os->flags() & elfcpp::SHF_ALLOC) != 0);
1533 bool is_write = (os->flags() & elfcpp::SHF_WRITE) != 0;
1534 bool is_execinstr = (os->flags() & elfcpp::SHF_EXECINSTR) != 0;
1535 bool is_bss = false;
1540 case elfcpp::SHT_PROGBITS:
1542 case elfcpp::SHT_NOBITS:
1545 case elfcpp::SHT_RELA:
1546 case elfcpp::SHT_REL:
1548 return ORDER_DYNAMIC_RELOCS;
1550 case elfcpp::SHT_HASH:
1551 case elfcpp::SHT_DYNAMIC:
1552 case elfcpp::SHT_SHLIB:
1553 case elfcpp::SHT_DYNSYM:
1554 case elfcpp::SHT_GNU_HASH:
1555 case elfcpp::SHT_GNU_verdef:
1556 case elfcpp::SHT_GNU_verneed:
1557 case elfcpp::SHT_GNU_versym:
1559 return ORDER_DYNAMIC_LINKER;
1561 case elfcpp::SHT_NOTE:
1562 return is_write ? ORDER_RW_NOTE : ORDER_RO_NOTE;
1565 if ((os->flags() & elfcpp::SHF_TLS) != 0)
1566 return is_bss ? ORDER_TLS_BSS : ORDER_TLS_DATA;
1568 if (!is_bss && !is_write)
1572 if (strcmp(os->name(), ".init") == 0)
1574 else if (strcmp(os->name(), ".fini") == 0)
1577 return is_execinstr ? ORDER_TEXT : ORDER_READONLY;
1581 return is_relro_local ? ORDER_RELRO_LOCAL : ORDER_RELRO;
1583 if (os->is_small_section())
1584 return is_bss ? ORDER_SMALL_BSS : ORDER_SMALL_DATA;
1585 if (os->is_large_section())
1586 return is_bss ? ORDER_LARGE_BSS : ORDER_LARGE_DATA;
1588 return is_bss ? ORDER_BSS : ORDER_DATA;
1591 // Attach output sections to segments. This is called after we have
1592 // seen all the input sections.
1595 Layout::attach_sections_to_segments(const Target* target)
1597 for (Section_list::iterator p = this->section_list_.begin();
1598 p != this->section_list_.end();
1600 this->attach_section_to_segment(target, *p);
1602 this->sections_are_attached_ = true;
1605 // Attach an output section to a segment.
1608 Layout::attach_section_to_segment(const Target* target, Output_section* os)
1610 if ((os->flags() & elfcpp::SHF_ALLOC) == 0)
1611 this->unattached_section_list_.push_back(os);
1613 this->attach_allocated_section_to_segment(target, os);
1616 // Attach an allocated output section to a segment.
1619 Layout::attach_allocated_section_to_segment(const Target* target,
1622 elfcpp::Elf_Xword flags = os->flags();
1623 gold_assert((flags & elfcpp::SHF_ALLOC) != 0);
1625 if (parameters->options().relocatable())
1628 // If we have a SECTIONS clause, we can't handle the attachment to
1629 // segments until after we've seen all the sections.
1630 if (this->script_options_->saw_sections_clause())
1633 gold_assert(!this->script_options_->saw_phdrs_clause());
1635 // This output section goes into a PT_LOAD segment.
1637 elfcpp::Elf_Word seg_flags = Layout::section_flags_to_segment(flags);
1639 // Check for --section-start.
1641 bool is_address_set = parameters->options().section_start(os->name(), &addr);
1643 // In general the only thing we really care about for PT_LOAD
1644 // segments is whether or not they are writable or executable,
1645 // so that is how we search for them.
1646 // Large data sections also go into their own PT_LOAD segment.
1647 // People who need segments sorted on some other basis will
1648 // have to use a linker script.
1650 Segment_list::const_iterator p;
1651 for (p = this->segment_list_.begin();
1652 p != this->segment_list_.end();
1655 if ((*p)->type() != elfcpp::PT_LOAD)
1657 if (!parameters->options().omagic()
1658 && ((*p)->flags() & elfcpp::PF_W) != (seg_flags & elfcpp::PF_W))
1660 if ((target->isolate_execinstr() || parameters->options().rosegment())
1661 && ((*p)->flags() & elfcpp::PF_X) != (seg_flags & elfcpp::PF_X))
1663 // If -Tbss was specified, we need to separate the data and BSS
1665 if (parameters->options().user_set_Tbss())
1667 if ((os->type() == elfcpp::SHT_NOBITS)
1668 == (*p)->has_any_data_sections())
1671 if (os->is_large_data_section() && !(*p)->is_large_data_segment())
1676 if ((*p)->are_addresses_set())
1679 (*p)->add_initial_output_data(os);
1680 (*p)->update_flags_for_output_section(seg_flags);
1681 (*p)->set_addresses(addr, addr);
1685 (*p)->add_output_section_to_load(this, os, seg_flags);
1689 if (p == this->segment_list_.end())
1691 Output_segment* oseg = this->make_output_segment(elfcpp::PT_LOAD,
1693 if (os->is_large_data_section())
1694 oseg->set_is_large_data_segment();
1695 oseg->add_output_section_to_load(this, os, seg_flags);
1697 oseg->set_addresses(addr, addr);
1700 // If we see a loadable SHT_NOTE section, we create a PT_NOTE
1702 if (os->type() == elfcpp::SHT_NOTE)
1704 // See if we already have an equivalent PT_NOTE segment.
1705 for (p = this->segment_list_.begin();
1706 p != segment_list_.end();
1709 if ((*p)->type() == elfcpp::PT_NOTE
1710 && (((*p)->flags() & elfcpp::PF_W)
1711 == (seg_flags & elfcpp::PF_W)))
1713 (*p)->add_output_section_to_nonload(os, seg_flags);
1718 if (p == this->segment_list_.end())
1720 Output_segment* oseg = this->make_output_segment(elfcpp::PT_NOTE,
1722 oseg->add_output_section_to_nonload(os, seg_flags);
1726 // If we see a loadable SHF_TLS section, we create a PT_TLS
1727 // segment. There can only be one such segment.
1728 if ((flags & elfcpp::SHF_TLS) != 0)
1730 if (this->tls_segment_ == NULL)
1731 this->make_output_segment(elfcpp::PT_TLS, seg_flags);
1732 this->tls_segment_->add_output_section_to_nonload(os, seg_flags);
1735 // If -z relro is in effect, and we see a relro section, we create a
1736 // PT_GNU_RELRO segment. There can only be one such segment.
1737 if (os->is_relro() && parameters->options().relro())
1739 gold_assert(seg_flags == (elfcpp::PF_R | elfcpp::PF_W));
1740 if (this->relro_segment_ == NULL)
1741 this->make_output_segment(elfcpp::PT_GNU_RELRO, seg_flags);
1742 this->relro_segment_->add_output_section_to_nonload(os, seg_flags);
1745 // If we see a section named .interp, put it into a PT_INTERP
1746 // segment. This seems broken to me, but this is what GNU ld does,
1747 // and glibc expects it.
1748 if (strcmp(os->name(), ".interp") == 0
1749 && !this->script_options_->saw_phdrs_clause())
1751 if (this->interp_segment_ == NULL)
1752 this->make_output_segment(elfcpp::PT_INTERP, seg_flags);
1754 gold_warning(_("multiple '.interp' sections in input files "
1755 "may cause confusing PT_INTERP segment"));
1756 this->interp_segment_->add_output_section_to_nonload(os, seg_flags);
1760 // Make an output section for a script.
1763 Layout::make_output_section_for_script(
1765 Script_sections::Section_type section_type)
1767 name = this->namepool_.add(name, false, NULL);
1768 elfcpp::Elf_Xword sh_flags = elfcpp::SHF_ALLOC;
1769 if (section_type == Script_sections::ST_NOLOAD)
1771 Output_section* os = this->make_output_section(name, elfcpp::SHT_PROGBITS,
1772 sh_flags, ORDER_INVALID,
1774 os->set_found_in_sections_clause();
1775 if (section_type == Script_sections::ST_NOLOAD)
1776 os->set_is_noload();
1780 // Return the number of segments we expect to see.
1783 Layout::expected_segment_count() const
1785 size_t ret = this->segment_list_.size();
1787 // If we didn't see a SECTIONS clause in a linker script, we should
1788 // already have the complete list of segments. Otherwise we ask the
1789 // SECTIONS clause how many segments it expects, and add in the ones
1790 // we already have (PT_GNU_STACK, PT_GNU_EH_FRAME, etc.)
1792 if (!this->script_options_->saw_sections_clause())
1796 const Script_sections* ss = this->script_options_->script_sections();
1797 return ret + ss->expected_segment_count(this);
1801 // Handle the .note.GNU-stack section at layout time. SEEN_GNU_STACK
1802 // is whether we saw a .note.GNU-stack section in the object file.
1803 // GNU_STACK_FLAGS is the section flags. The flags give the
1804 // protection required for stack memory. We record this in an
1805 // executable as a PT_GNU_STACK segment. If an object file does not
1806 // have a .note.GNU-stack segment, we must assume that it is an old
1807 // object. On some targets that will force an executable stack.
1810 Layout::layout_gnu_stack(bool seen_gnu_stack, uint64_t gnu_stack_flags,
1813 if (!seen_gnu_stack)
1815 this->input_without_gnu_stack_note_ = true;
1816 if (parameters->options().warn_execstack()
1817 && parameters->target().is_default_stack_executable())
1818 gold_warning(_("%s: missing .note.GNU-stack section"
1819 " implies executable stack"),
1820 obj->name().c_str());
1824 this->input_with_gnu_stack_note_ = true;
1825 if ((gnu_stack_flags & elfcpp::SHF_EXECINSTR) != 0)
1827 this->input_requires_executable_stack_ = true;
1828 if (parameters->options().warn_execstack()
1829 || parameters->options().is_stack_executable())
1830 gold_warning(_("%s: requires executable stack"),
1831 obj->name().c_str());
1836 // Create automatic note sections.
1839 Layout::create_notes()
1841 this->create_gold_note();
1842 this->create_executable_stack_info();
1843 this->create_build_id();
1846 // Create the dynamic sections which are needed before we read the
1850 Layout::create_initial_dynamic_sections(Symbol_table* symtab)
1852 if (parameters->doing_static_link())
1855 this->dynamic_section_ = this->choose_output_section(NULL, ".dynamic",
1856 elfcpp::SHT_DYNAMIC,
1858 | elfcpp::SHF_WRITE),
1862 // A linker script may discard .dynamic, so check for NULL.
1863 if (this->dynamic_section_ != NULL)
1865 this->dynamic_symbol_ =
1866 symtab->define_in_output_data("_DYNAMIC", NULL,
1867 Symbol_table::PREDEFINED,
1868 this->dynamic_section_, 0, 0,
1869 elfcpp::STT_OBJECT, elfcpp::STB_LOCAL,
1870 elfcpp::STV_HIDDEN, 0, false, false);
1872 this->dynamic_data_ = new Output_data_dynamic(&this->dynpool_);
1874 this->dynamic_section_->add_output_section_data(this->dynamic_data_);
1878 // For each output section whose name can be represented as C symbol,
1879 // define __start and __stop symbols for the section. This is a GNU
1883 Layout::define_section_symbols(Symbol_table* symtab)
1885 for (Section_list::const_iterator p = this->section_list_.begin();
1886 p != this->section_list_.end();
1889 const char* const name = (*p)->name();
1890 if (is_cident(name))
1892 const std::string name_string(name);
1893 const std::string start_name(cident_section_start_prefix
1895 const std::string stop_name(cident_section_stop_prefix
1898 symtab->define_in_output_data(start_name.c_str(),
1900 Symbol_table::PREDEFINED,
1906 elfcpp::STV_DEFAULT,
1908 false, // offset_is_from_end
1909 true); // only_if_ref
1911 symtab->define_in_output_data(stop_name.c_str(),
1913 Symbol_table::PREDEFINED,
1919 elfcpp::STV_DEFAULT,
1921 true, // offset_is_from_end
1922 true); // only_if_ref
1927 // Define symbols for group signatures.
1930 Layout::define_group_signatures(Symbol_table* symtab)
1932 for (Group_signatures::iterator p = this->group_signatures_.begin();
1933 p != this->group_signatures_.end();
1936 Symbol* sym = symtab->lookup(p->signature, NULL);
1938 p->section->set_info_symndx(sym);
1941 // Force the name of the group section to the group
1942 // signature, and use the group's section symbol as the
1943 // signature symbol.
1944 if (strcmp(p->section->name(), p->signature) != 0)
1946 const char* name = this->namepool_.add(p->signature,
1948 p->section->set_name(name);
1950 p->section->set_needs_symtab_index();
1951 p->section->set_info_section_symndx(p->section);
1955 this->group_signatures_.clear();
1958 // Find the first read-only PT_LOAD segment, creating one if
1962 Layout::find_first_load_seg(const Target* target)
1964 Output_segment* best = NULL;
1965 for (Segment_list::const_iterator p = this->segment_list_.begin();
1966 p != this->segment_list_.end();
1969 if ((*p)->type() == elfcpp::PT_LOAD
1970 && ((*p)->flags() & elfcpp::PF_R) != 0
1971 && (parameters->options().omagic()
1972 || ((*p)->flags() & elfcpp::PF_W) == 0)
1973 && (!target->isolate_execinstr()
1974 || ((*p)->flags() & elfcpp::PF_X) == 0))
1976 if (best == NULL || this->segment_precedes(*p, best))
1983 gold_assert(!this->script_options_->saw_phdrs_clause());
1985 Output_segment* load_seg = this->make_output_segment(elfcpp::PT_LOAD,
1990 // Save states of all current output segments. Store saved states
1991 // in SEGMENT_STATES.
1994 Layout::save_segments(Segment_states* segment_states)
1996 for (Segment_list::const_iterator p = this->segment_list_.begin();
1997 p != this->segment_list_.end();
2000 Output_segment* segment = *p;
2002 Output_segment* copy = new Output_segment(*segment);
2003 (*segment_states)[segment] = copy;
2007 // Restore states of output segments and delete any segment not found in
2011 Layout::restore_segments(const Segment_states* segment_states)
2013 // Go through the segment list and remove any segment added in the
2015 this->tls_segment_ = NULL;
2016 this->relro_segment_ = NULL;
2017 Segment_list::iterator list_iter = this->segment_list_.begin();
2018 while (list_iter != this->segment_list_.end())
2020 Output_segment* segment = *list_iter;
2021 Segment_states::const_iterator states_iter =
2022 segment_states->find(segment);
2023 if (states_iter != segment_states->end())
2025 const Output_segment* copy = states_iter->second;
2026 // Shallow copy to restore states.
2029 // Also fix up TLS and RELRO segment pointers as appropriate.
2030 if (segment->type() == elfcpp::PT_TLS)
2031 this->tls_segment_ = segment;
2032 else if (segment->type() == elfcpp::PT_GNU_RELRO)
2033 this->relro_segment_ = segment;
2039 list_iter = this->segment_list_.erase(list_iter);
2040 // This is a segment created during section layout. It should be
2041 // safe to remove it since we should have removed all pointers to it.
2047 // Clean up after relaxation so that sections can be laid out again.
2050 Layout::clean_up_after_relaxation()
2052 // Restore the segments to point state just prior to the relaxation loop.
2053 Script_sections* script_section = this->script_options_->script_sections();
2054 script_section->release_segments();
2055 this->restore_segments(this->segment_states_);
2057 // Reset section addresses and file offsets
2058 for (Section_list::iterator p = this->section_list_.begin();
2059 p != this->section_list_.end();
2062 (*p)->restore_states();
2064 // If an input section changes size because of relaxation,
2065 // we need to adjust the section offsets of all input sections.
2066 // after such a section.
2067 if ((*p)->section_offsets_need_adjustment())
2068 (*p)->adjust_section_offsets();
2070 (*p)->reset_address_and_file_offset();
2073 // Reset special output object address and file offsets.
2074 for (Data_list::iterator p = this->special_output_list_.begin();
2075 p != this->special_output_list_.end();
2077 (*p)->reset_address_and_file_offset();
2079 // A linker script may have created some output section data objects.
2080 // They are useless now.
2081 for (Output_section_data_list::const_iterator p =
2082 this->script_output_section_data_list_.begin();
2083 p != this->script_output_section_data_list_.end();
2086 this->script_output_section_data_list_.clear();
2089 // Prepare for relaxation.
2092 Layout::prepare_for_relaxation()
2094 // Create an relaxation debug check if in debugging mode.
2095 if (is_debugging_enabled(DEBUG_RELAXATION))
2096 this->relaxation_debug_check_ = new Relaxation_debug_check();
2098 // Save segment states.
2099 this->segment_states_ = new Segment_states();
2100 this->save_segments(this->segment_states_);
2102 for(Section_list::const_iterator p = this->section_list_.begin();
2103 p != this->section_list_.end();
2105 (*p)->save_states();
2107 if (is_debugging_enabled(DEBUG_RELAXATION))
2108 this->relaxation_debug_check_->check_output_data_for_reset_values(
2109 this->section_list_, this->special_output_list_);
2111 // Also enable recording of output section data from scripts.
2112 this->record_output_section_data_from_script_ = true;
2115 // Relaxation loop body: If target has no relaxation, this runs only once
2116 // Otherwise, the target relaxation hook is called at the end of
2117 // each iteration. If the hook returns true, it means re-layout of
2118 // section is required.
2120 // The number of segments created by a linking script without a PHDRS
2121 // clause may be affected by section sizes and alignments. There is
2122 // a remote chance that relaxation causes different number of PT_LOAD
2123 // segments are created and sections are attached to different segments.
2124 // Therefore, we always throw away all segments created during section
2125 // layout. In order to be able to restart the section layout, we keep
2126 // a copy of the segment list right before the relaxation loop and use
2127 // that to restore the segments.
2129 // PASS is the current relaxation pass number.
2130 // SYMTAB is a symbol table.
2131 // PLOAD_SEG is the address of a pointer for the load segment.
2132 // PHDR_SEG is a pointer to the PHDR segment.
2133 // SEGMENT_HEADERS points to the output segment header.
2134 // FILE_HEADER points to the output file header.
2135 // PSHNDX is the address to store the output section index.
2138 Layout::relaxation_loop_body(
2141 Symbol_table* symtab,
2142 Output_segment** pload_seg,
2143 Output_segment* phdr_seg,
2144 Output_segment_headers* segment_headers,
2145 Output_file_header* file_header,
2146 unsigned int* pshndx)
2148 // If this is not the first iteration, we need to clean up after
2149 // relaxation so that we can lay out the sections again.
2151 this->clean_up_after_relaxation();
2153 // If there is a SECTIONS clause, put all the input sections into
2154 // the required order.
2155 Output_segment* load_seg;
2156 if (this->script_options_->saw_sections_clause())
2157 load_seg = this->set_section_addresses_from_script(symtab);
2158 else if (parameters->options().relocatable())
2161 load_seg = this->find_first_load_seg(target);
2163 if (parameters->options().oformat_enum()
2164 != General_options::OBJECT_FORMAT_ELF)
2167 // If the user set the address of the text segment, that may not be
2168 // compatible with putting the segment headers and file headers into
2170 if (parameters->options().user_set_Ttext()
2171 && parameters->options().Ttext() % target->common_pagesize() != 0)
2177 gold_assert(phdr_seg == NULL
2179 || this->script_options_->saw_sections_clause());
2181 // If the address of the load segment we found has been set by
2182 // --section-start rather than by a script, then adjust the VMA and
2183 // LMA downward if possible to include the file and section headers.
2184 uint64_t header_gap = 0;
2185 if (load_seg != NULL
2186 && load_seg->are_addresses_set()
2187 && !this->script_options_->saw_sections_clause()
2188 && !parameters->options().relocatable())
2190 file_header->finalize_data_size();
2191 segment_headers->finalize_data_size();
2192 size_t sizeof_headers = (file_header->data_size()
2193 + segment_headers->data_size());
2194 const uint64_t abi_pagesize = target->abi_pagesize();
2195 uint64_t hdr_paddr = load_seg->paddr() - sizeof_headers;
2196 hdr_paddr &= ~(abi_pagesize - 1);
2197 uint64_t subtract = load_seg->paddr() - hdr_paddr;
2198 if (load_seg->paddr() < subtract || load_seg->vaddr() < subtract)
2202 load_seg->set_addresses(load_seg->vaddr() - subtract,
2203 load_seg->paddr() - subtract);
2204 header_gap = subtract - sizeof_headers;
2208 // Lay out the segment headers.
2209 if (!parameters->options().relocatable())
2211 gold_assert(segment_headers != NULL);
2212 if (header_gap != 0 && load_seg != NULL)
2214 Output_data_zero_fill* z = new Output_data_zero_fill(header_gap, 1);
2215 load_seg->add_initial_output_data(z);
2217 if (load_seg != NULL)
2218 load_seg->add_initial_output_data(segment_headers);
2219 if (phdr_seg != NULL)
2220 phdr_seg->add_initial_output_data(segment_headers);
2223 // Lay out the file header.
2224 if (load_seg != NULL)
2225 load_seg->add_initial_output_data(file_header);
2227 if (this->script_options_->saw_phdrs_clause()
2228 && !parameters->options().relocatable())
2230 // Support use of FILEHDRS and PHDRS attachments in a PHDRS
2231 // clause in a linker script.
2232 Script_sections* ss = this->script_options_->script_sections();
2233 ss->put_headers_in_phdrs(file_header, segment_headers);
2236 // We set the output section indexes in set_segment_offsets and
2237 // set_section_indexes.
2240 // Set the file offsets of all the segments, and all the sections
2243 if (!parameters->options().relocatable())
2244 off = this->set_segment_offsets(target, load_seg, pshndx);
2246 off = this->set_relocatable_section_offsets(file_header, pshndx);
2248 // Verify that the dummy relaxation does not change anything.
2249 if (is_debugging_enabled(DEBUG_RELAXATION))
2252 this->relaxation_debug_check_->read_sections(this->section_list_);
2254 this->relaxation_debug_check_->verify_sections(this->section_list_);
2257 *pload_seg = load_seg;
2261 // Search the list of patterns and find the postion of the given section
2262 // name in the output section. If the section name matches a glob
2263 // pattern and a non-glob name, then the non-glob position takes
2264 // precedence. Return 0 if no match is found.
2267 Layout::find_section_order_index(const std::string& section_name)
2269 Unordered_map<std::string, unsigned int>::iterator map_it;
2270 map_it = this->input_section_position_.find(section_name);
2271 if (map_it != this->input_section_position_.end())
2272 return map_it->second;
2274 // Absolute match failed. Linear search the glob patterns.
2275 std::vector<std::string>::iterator it;
2276 for (it = this->input_section_glob_.begin();
2277 it != this->input_section_glob_.end();
2280 if (fnmatch((*it).c_str(), section_name.c_str(), FNM_NOESCAPE) == 0)
2282 map_it = this->input_section_position_.find(*it);
2283 gold_assert(map_it != this->input_section_position_.end());
2284 return map_it->second;
2290 // Read the sequence of input sections from the file specified with
2291 // option --section-ordering-file.
2294 Layout::read_layout_from_file()
2296 const char* filename = parameters->options().section_ordering_file();
2302 gold_fatal(_("unable to open --section-ordering-file file %s: %s"),
2303 filename, strerror(errno));
2305 std::getline(in, line); // this chops off the trailing \n, if any
2306 unsigned int position = 1;
2307 this->set_section_ordering_specified();
2311 if (!line.empty() && line[line.length() - 1] == '\r') // Windows
2312 line.resize(line.length() - 1);
2313 // Ignore comments, beginning with '#'
2316 std::getline(in, line);
2319 this->input_section_position_[line] = position;
2320 // Store all glob patterns in a vector.
2321 if (is_wildcard_string(line.c_str()))
2322 this->input_section_glob_.push_back(line);
2324 std::getline(in, line);
2328 // Finalize the layout. When this is called, we have created all the
2329 // output sections and all the output segments which are based on
2330 // input sections. We have several things to do, and we have to do
2331 // them in the right order, so that we get the right results correctly
2334 // 1) Finalize the list of output segments and create the segment
2337 // 2) Finalize the dynamic symbol table and associated sections.
2339 // 3) Determine the final file offset of all the output segments.
2341 // 4) Determine the final file offset of all the SHF_ALLOC output
2344 // 5) Create the symbol table sections and the section name table
2347 // 6) Finalize the symbol table: set symbol values to their final
2348 // value and make a final determination of which symbols are going
2349 // into the output symbol table.
2351 // 7) Create the section table header.
2353 // 8) Determine the final file offset of all the output sections which
2354 // are not SHF_ALLOC, including the section table header.
2356 // 9) Finalize the ELF file header.
2358 // This function returns the size of the output file.
2361 Layout::finalize(const Input_objects* input_objects, Symbol_table* symtab,
2362 Target* target, const Task* task)
2364 target->finalize_sections(this, input_objects, symtab);
2366 this->count_local_symbols(task, input_objects);
2368 this->link_stabs_sections();
2370 Output_segment* phdr_seg = NULL;
2371 if (!parameters->options().relocatable() && !parameters->doing_static_link())
2373 // There was a dynamic object in the link. We need to create
2374 // some information for the dynamic linker.
2376 // Create the PT_PHDR segment which will hold the program
2378 if (!this->script_options_->saw_phdrs_clause())
2379 phdr_seg = this->make_output_segment(elfcpp::PT_PHDR, elfcpp::PF_R);
2381 // Create the dynamic symbol table, including the hash table.
2382 Output_section* dynstr;
2383 std::vector<Symbol*> dynamic_symbols;
2384 unsigned int local_dynamic_count;
2385 Versions versions(*this->script_options()->version_script_info(),
2387 this->create_dynamic_symtab(input_objects, symtab, &dynstr,
2388 &local_dynamic_count, &dynamic_symbols,
2391 // Create the .interp section to hold the name of the
2392 // interpreter, and put it in a PT_INTERP segment. Don't do it
2393 // if we saw a .interp section in an input file.
2394 if ((!parameters->options().shared()
2395 || parameters->options().dynamic_linker() != NULL)
2396 && this->interp_segment_ == NULL)
2397 this->create_interp(target);
2399 // Finish the .dynamic section to hold the dynamic data, and put
2400 // it in a PT_DYNAMIC segment.
2401 this->finish_dynamic_section(input_objects, symtab);
2403 // We should have added everything we need to the dynamic string
2405 this->dynpool_.set_string_offsets();
2407 // Create the version sections. We can't do this until the
2408 // dynamic string table is complete.
2409 this->create_version_sections(&versions, symtab, local_dynamic_count,
2410 dynamic_symbols, dynstr);
2412 // Set the size of the _DYNAMIC symbol. We can't do this until
2413 // after we call create_version_sections.
2414 this->set_dynamic_symbol_size(symtab);
2417 // Create segment headers.
2418 Output_segment_headers* segment_headers =
2419 (parameters->options().relocatable()
2421 : new Output_segment_headers(this->segment_list_));
2423 // Lay out the file header.
2424 Output_file_header* file_header = new Output_file_header(target, symtab,
2427 this->special_output_list_.push_back(file_header);
2428 if (segment_headers != NULL)
2429 this->special_output_list_.push_back(segment_headers);
2431 // Find approriate places for orphan output sections if we are using
2433 if (this->script_options_->saw_sections_clause())
2434 this->place_orphan_sections_in_script();
2436 Output_segment* load_seg;
2441 // Take a snapshot of the section layout as needed.
2442 if (target->may_relax())
2443 this->prepare_for_relaxation();
2445 // Run the relaxation loop to lay out sections.
2448 off = this->relaxation_loop_body(pass, target, symtab, &load_seg,
2449 phdr_seg, segment_headers, file_header,
2453 while (target->may_relax()
2454 && target->relax(pass, input_objects, symtab, this, task));
2456 // Set the file offsets of all the non-data sections we've seen so
2457 // far which don't have to wait for the input sections. We need
2458 // this in order to finalize local symbols in non-allocated
2460 off = this->set_section_offsets(off, BEFORE_INPUT_SECTIONS_PASS);
2462 // Set the section indexes of all unallocated sections seen so far,
2463 // in case any of them are somehow referenced by a symbol.
2464 shndx = this->set_section_indexes(shndx);
2466 // Create the symbol table sections.
2467 this->create_symtab_sections(input_objects, symtab, shndx, &off);
2468 if (!parameters->doing_static_link())
2469 this->assign_local_dynsym_offsets(input_objects);
2471 // Process any symbol assignments from a linker script. This must
2472 // be called after the symbol table has been finalized.
2473 this->script_options_->finalize_symbols(symtab, this);
2475 // Create the incremental inputs sections.
2476 if (this->incremental_inputs_)
2478 this->incremental_inputs_->finalize();
2479 this->create_incremental_info_sections(symtab);
2482 // Create the .shstrtab section.
2483 Output_section* shstrtab_section = this->create_shstrtab();
2485 // Set the file offsets of the rest of the non-data sections which
2486 // don't have to wait for the input sections.
2487 off = this->set_section_offsets(off, BEFORE_INPUT_SECTIONS_PASS);
2489 // Now that all sections have been created, set the section indexes
2490 // for any sections which haven't been done yet.
2491 shndx = this->set_section_indexes(shndx);
2493 // Create the section table header.
2494 this->create_shdrs(shstrtab_section, &off);
2496 // If there are no sections which require postprocessing, we can
2497 // handle the section names now, and avoid a resize later.
2498 if (!this->any_postprocessing_sections_)
2500 off = this->set_section_offsets(off,
2501 POSTPROCESSING_SECTIONS_PASS);
2503 this->set_section_offsets(off,
2504 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS);
2507 file_header->set_section_info(this->section_headers_, shstrtab_section);
2509 // Now we know exactly where everything goes in the output file
2510 // (except for non-allocated sections which require postprocessing).
2511 Output_data::layout_complete();
2513 this->output_file_size_ = off;
2518 // Create a note header following the format defined in the ELF ABI.
2519 // NAME is the name, NOTE_TYPE is the type, SECTION_NAME is the name
2520 // of the section to create, DESCSZ is the size of the descriptor.
2521 // ALLOCATE is true if the section should be allocated in memory.
2522 // This returns the new note section. It sets *TRAILING_PADDING to
2523 // the number of trailing zero bytes required.
2526 Layout::create_note(const char* name, int note_type,
2527 const char* section_name, size_t descsz,
2528 bool allocate, size_t* trailing_padding)
2530 // Authorities all agree that the values in a .note field should
2531 // be aligned on 4-byte boundaries for 32-bit binaries. However,
2532 // they differ on what the alignment is for 64-bit binaries.
2533 // The GABI says unambiguously they take 8-byte alignment:
2534 // http://sco.com/developers/gabi/latest/ch5.pheader.html#note_section
2535 // Other documentation says alignment should always be 4 bytes:
2536 // http://www.netbsd.org/docs/kernel/elf-notes.html#note-format
2537 // GNU ld and GNU readelf both support the latter (at least as of
2538 // version 2.16.91), and glibc always generates the latter for
2539 // .note.ABI-tag (as of version 1.6), so that's the one we go with
2541 #ifdef GABI_FORMAT_FOR_DOTNOTE_SECTION // This is not defined by default.
2542 const int size = parameters->target().get_size();
2544 const int size = 32;
2547 // The contents of the .note section.
2548 size_t namesz = strlen(name) + 1;
2549 size_t aligned_namesz = align_address(namesz, size / 8);
2550 size_t aligned_descsz = align_address(descsz, size / 8);
2552 size_t notehdrsz = 3 * (size / 8) + aligned_namesz;
2554 unsigned char* buffer = new unsigned char[notehdrsz];
2555 memset(buffer, 0, notehdrsz);
2557 bool is_big_endian = parameters->target().is_big_endian();
2563 elfcpp::Swap<32, false>::writeval(buffer, namesz);
2564 elfcpp::Swap<32, false>::writeval(buffer + 4, descsz);
2565 elfcpp::Swap<32, false>::writeval(buffer + 8, note_type);
2569 elfcpp::Swap<32, true>::writeval(buffer, namesz);
2570 elfcpp::Swap<32, true>::writeval(buffer + 4, descsz);
2571 elfcpp::Swap<32, true>::writeval(buffer + 8, note_type);
2574 else if (size == 64)
2578 elfcpp::Swap<64, false>::writeval(buffer, namesz);
2579 elfcpp::Swap<64, false>::writeval(buffer + 8, descsz);
2580 elfcpp::Swap<64, false>::writeval(buffer + 16, note_type);
2584 elfcpp::Swap<64, true>::writeval(buffer, namesz);
2585 elfcpp::Swap<64, true>::writeval(buffer + 8, descsz);
2586 elfcpp::Swap<64, true>::writeval(buffer + 16, note_type);
2592 memcpy(buffer + 3 * (size / 8), name, namesz);
2594 elfcpp::Elf_Xword flags = 0;
2595 Output_section_order order = ORDER_INVALID;
2598 flags = elfcpp::SHF_ALLOC;
2599 order = ORDER_RO_NOTE;
2601 Output_section* os = this->choose_output_section(NULL, section_name,
2603 flags, false, order, false);
2607 Output_section_data* posd = new Output_data_const_buffer(buffer, notehdrsz,
2610 os->add_output_section_data(posd);
2612 *trailing_padding = aligned_descsz - descsz;
2617 // For an executable or shared library, create a note to record the
2618 // version of gold used to create the binary.
2621 Layout::create_gold_note()
2623 if (parameters->options().relocatable()
2624 || parameters->incremental_update())
2627 std::string desc = std::string("gold ") + gold::get_version_string();
2629 size_t trailing_padding;
2630 Output_section* os = this->create_note("GNU", elfcpp::NT_GNU_GOLD_VERSION,
2631 ".note.gnu.gold-version", desc.size(),
2632 false, &trailing_padding);
2636 Output_section_data* posd = new Output_data_const(desc, 4);
2637 os->add_output_section_data(posd);
2639 if (trailing_padding > 0)
2641 posd = new Output_data_zero_fill(trailing_padding, 0);
2642 os->add_output_section_data(posd);
2646 // Record whether the stack should be executable. This can be set
2647 // from the command line using the -z execstack or -z noexecstack
2648 // options. Otherwise, if any input file has a .note.GNU-stack
2649 // section with the SHF_EXECINSTR flag set, the stack should be
2650 // executable. Otherwise, if at least one input file a
2651 // .note.GNU-stack section, and some input file has no .note.GNU-stack
2652 // section, we use the target default for whether the stack should be
2653 // executable. Otherwise, we don't generate a stack note. When
2654 // generating a object file, we create a .note.GNU-stack section with
2655 // the appropriate marking. When generating an executable or shared
2656 // library, we create a PT_GNU_STACK segment.
2659 Layout::create_executable_stack_info()
2661 bool is_stack_executable;
2662 if (parameters->options().is_execstack_set())
2663 is_stack_executable = parameters->options().is_stack_executable();
2664 else if (!this->input_with_gnu_stack_note_)
2668 if (this->input_requires_executable_stack_)
2669 is_stack_executable = true;
2670 else if (this->input_without_gnu_stack_note_)
2671 is_stack_executable =
2672 parameters->target().is_default_stack_executable();
2674 is_stack_executable = false;
2677 if (parameters->options().relocatable())
2679 const char* name = this->namepool_.add(".note.GNU-stack", false, NULL);
2680 elfcpp::Elf_Xword flags = 0;
2681 if (is_stack_executable)
2682 flags |= elfcpp::SHF_EXECINSTR;
2683 this->make_output_section(name, elfcpp::SHT_PROGBITS, flags,
2684 ORDER_INVALID, false);
2688 if (this->script_options_->saw_phdrs_clause())
2690 int flags = elfcpp::PF_R | elfcpp::PF_W;
2691 if (is_stack_executable)
2692 flags |= elfcpp::PF_X;
2693 this->make_output_segment(elfcpp::PT_GNU_STACK, flags);
2697 // If --build-id was used, set up the build ID note.
2700 Layout::create_build_id()
2702 if (!parameters->options().user_set_build_id())
2705 const char* style = parameters->options().build_id();
2706 if (strcmp(style, "none") == 0)
2709 // Set DESCSZ to the size of the note descriptor. When possible,
2710 // set DESC to the note descriptor contents.
2713 if (strcmp(style, "md5") == 0)
2715 else if (strcmp(style, "sha1") == 0)
2717 else if (strcmp(style, "uuid") == 0)
2719 const size_t uuidsz = 128 / 8;
2721 char buffer[uuidsz];
2722 memset(buffer, 0, uuidsz);
2724 int descriptor = open_descriptor(-1, "/dev/urandom", O_RDONLY);
2726 gold_error(_("--build-id=uuid failed: could not open /dev/urandom: %s"),
2730 ssize_t got = ::read(descriptor, buffer, uuidsz);
2731 release_descriptor(descriptor, true);
2733 gold_error(_("/dev/urandom: read failed: %s"), strerror(errno));
2734 else if (static_cast<size_t>(got) != uuidsz)
2735 gold_error(_("/dev/urandom: expected %zu bytes, got %zd bytes"),
2739 desc.assign(buffer, uuidsz);
2742 else if (strncmp(style, "0x", 2) == 0)
2745 const char* p = style + 2;
2748 if (hex_p(p[0]) && hex_p(p[1]))
2750 char c = (hex_value(p[0]) << 4) | hex_value(p[1]);
2754 else if (*p == '-' || *p == ':')
2757 gold_fatal(_("--build-id argument '%s' not a valid hex number"),
2760 descsz = desc.size();
2763 gold_fatal(_("unrecognized --build-id argument '%s'"), style);
2766 size_t trailing_padding;
2767 Output_section* os = this->create_note("GNU", elfcpp::NT_GNU_BUILD_ID,
2768 ".note.gnu.build-id", descsz, true,
2775 // We know the value already, so we fill it in now.
2776 gold_assert(desc.size() == descsz);
2778 Output_section_data* posd = new Output_data_const(desc, 4);
2779 os->add_output_section_data(posd);
2781 if (trailing_padding != 0)
2783 posd = new Output_data_zero_fill(trailing_padding, 0);
2784 os->add_output_section_data(posd);
2789 // We need to compute a checksum after we have completed the
2791 gold_assert(trailing_padding == 0);
2792 this->build_id_note_ = new Output_data_zero_fill(descsz, 4);
2793 os->add_output_section_data(this->build_id_note_);
2797 // If we have both .stabXX and .stabXXstr sections, then the sh_link
2798 // field of the former should point to the latter. I'm not sure who
2799 // started this, but the GNU linker does it, and some tools depend
2803 Layout::link_stabs_sections()
2805 if (!this->have_stabstr_section_)
2808 for (Section_list::iterator p = this->section_list_.begin();
2809 p != this->section_list_.end();
2812 if ((*p)->type() != elfcpp::SHT_STRTAB)
2815 const char* name = (*p)->name();
2816 if (strncmp(name, ".stab", 5) != 0)
2819 size_t len = strlen(name);
2820 if (strcmp(name + len - 3, "str") != 0)
2823 std::string stab_name(name, len - 3);
2824 Output_section* stab_sec;
2825 stab_sec = this->find_output_section(stab_name.c_str());
2826 if (stab_sec != NULL)
2827 stab_sec->set_link_section(*p);
2831 // Create .gnu_incremental_inputs and related sections needed
2832 // for the next run of incremental linking to check what has changed.
2835 Layout::create_incremental_info_sections(Symbol_table* symtab)
2837 Incremental_inputs* incr = this->incremental_inputs_;
2839 gold_assert(incr != NULL);
2841 // Create the .gnu_incremental_inputs, _symtab, and _relocs input sections.
2842 incr->create_data_sections(symtab);
2844 // Add the .gnu_incremental_inputs section.
2845 const char* incremental_inputs_name =
2846 this->namepool_.add(".gnu_incremental_inputs", false, NULL);
2847 Output_section* incremental_inputs_os =
2848 this->make_output_section(incremental_inputs_name,
2849 elfcpp::SHT_GNU_INCREMENTAL_INPUTS, 0,
2850 ORDER_INVALID, false);
2851 incremental_inputs_os->add_output_section_data(incr->inputs_section());
2853 // Add the .gnu_incremental_symtab section.
2854 const char* incremental_symtab_name =
2855 this->namepool_.add(".gnu_incremental_symtab", false, NULL);
2856 Output_section* incremental_symtab_os =
2857 this->make_output_section(incremental_symtab_name,
2858 elfcpp::SHT_GNU_INCREMENTAL_SYMTAB, 0,
2859 ORDER_INVALID, false);
2860 incremental_symtab_os->add_output_section_data(incr->symtab_section());
2861 incremental_symtab_os->set_entsize(4);
2863 // Add the .gnu_incremental_relocs section.
2864 const char* incremental_relocs_name =
2865 this->namepool_.add(".gnu_incremental_relocs", false, NULL);
2866 Output_section* incremental_relocs_os =
2867 this->make_output_section(incremental_relocs_name,
2868 elfcpp::SHT_GNU_INCREMENTAL_RELOCS, 0,
2869 ORDER_INVALID, false);
2870 incremental_relocs_os->add_output_section_data(incr->relocs_section());
2871 incremental_relocs_os->set_entsize(incr->relocs_entsize());
2873 // Add the .gnu_incremental_got_plt section.
2874 const char* incremental_got_plt_name =
2875 this->namepool_.add(".gnu_incremental_got_plt", false, NULL);
2876 Output_section* incremental_got_plt_os =
2877 this->make_output_section(incremental_got_plt_name,
2878 elfcpp::SHT_GNU_INCREMENTAL_GOT_PLT, 0,
2879 ORDER_INVALID, false);
2880 incremental_got_plt_os->add_output_section_data(incr->got_plt_section());
2882 // Add the .gnu_incremental_strtab section.
2883 const char* incremental_strtab_name =
2884 this->namepool_.add(".gnu_incremental_strtab", false, NULL);
2885 Output_section* incremental_strtab_os = this->make_output_section(incremental_strtab_name,
2886 elfcpp::SHT_STRTAB, 0,
2887 ORDER_INVALID, false);
2888 Output_data_strtab* strtab_data =
2889 new Output_data_strtab(incr->get_stringpool());
2890 incremental_strtab_os->add_output_section_data(strtab_data);
2892 incremental_inputs_os->set_after_input_sections();
2893 incremental_symtab_os->set_after_input_sections();
2894 incremental_relocs_os->set_after_input_sections();
2895 incremental_got_plt_os->set_after_input_sections();
2897 incremental_inputs_os->set_link_section(incremental_strtab_os);
2898 incremental_symtab_os->set_link_section(incremental_inputs_os);
2899 incremental_relocs_os->set_link_section(incremental_inputs_os);
2900 incremental_got_plt_os->set_link_section(incremental_inputs_os);
2903 // Return whether SEG1 should be before SEG2 in the output file. This
2904 // is based entirely on the segment type and flags. When this is
2905 // called the segment addresses have normally not yet been set.
2908 Layout::segment_precedes(const Output_segment* seg1,
2909 const Output_segment* seg2)
2911 elfcpp::Elf_Word type1 = seg1->type();
2912 elfcpp::Elf_Word type2 = seg2->type();
2914 // The single PT_PHDR segment is required to precede any loadable
2915 // segment. We simply make it always first.
2916 if (type1 == elfcpp::PT_PHDR)
2918 gold_assert(type2 != elfcpp::PT_PHDR);
2921 if (type2 == elfcpp::PT_PHDR)
2924 // The single PT_INTERP segment is required to precede any loadable
2925 // segment. We simply make it always second.
2926 if (type1 == elfcpp::PT_INTERP)
2928 gold_assert(type2 != elfcpp::PT_INTERP);
2931 if (type2 == elfcpp::PT_INTERP)
2934 // We then put PT_LOAD segments before any other segments.
2935 if (type1 == elfcpp::PT_LOAD && type2 != elfcpp::PT_LOAD)
2937 if (type2 == elfcpp::PT_LOAD && type1 != elfcpp::PT_LOAD)
2940 // We put the PT_TLS segment last except for the PT_GNU_RELRO
2941 // segment, because that is where the dynamic linker expects to find
2942 // it (this is just for efficiency; other positions would also work
2944 if (type1 == elfcpp::PT_TLS
2945 && type2 != elfcpp::PT_TLS
2946 && type2 != elfcpp::PT_GNU_RELRO)
2948 if (type2 == elfcpp::PT_TLS
2949 && type1 != elfcpp::PT_TLS
2950 && type1 != elfcpp::PT_GNU_RELRO)
2953 // We put the PT_GNU_RELRO segment last, because that is where the
2954 // dynamic linker expects to find it (as with PT_TLS, this is just
2956 if (type1 == elfcpp::PT_GNU_RELRO && type2 != elfcpp::PT_GNU_RELRO)
2958 if (type2 == elfcpp::PT_GNU_RELRO && type1 != elfcpp::PT_GNU_RELRO)
2961 const elfcpp::Elf_Word flags1 = seg1->flags();
2962 const elfcpp::Elf_Word flags2 = seg2->flags();
2964 // The order of non-PT_LOAD segments is unimportant. We simply sort
2965 // by the numeric segment type and flags values. There should not
2966 // be more than one segment with the same type and flags.
2967 if (type1 != elfcpp::PT_LOAD)
2970 return type1 < type2;
2971 gold_assert(flags1 != flags2);
2972 return flags1 < flags2;
2975 // If the addresses are set already, sort by load address.
2976 if (seg1->are_addresses_set())
2978 if (!seg2->are_addresses_set())
2981 unsigned int section_count1 = seg1->output_section_count();
2982 unsigned int section_count2 = seg2->output_section_count();
2983 if (section_count1 == 0 && section_count2 > 0)
2985 if (section_count1 > 0 && section_count2 == 0)
2988 uint64_t paddr1 = (seg1->are_addresses_set()
2990 : seg1->first_section_load_address());
2991 uint64_t paddr2 = (seg2->are_addresses_set()
2993 : seg2->first_section_load_address());
2995 if (paddr1 != paddr2)
2996 return paddr1 < paddr2;
2998 else if (seg2->are_addresses_set())
3001 // A segment which holds large data comes after a segment which does
3002 // not hold large data.
3003 if (seg1->is_large_data_segment())
3005 if (!seg2->is_large_data_segment())
3008 else if (seg2->is_large_data_segment())
3011 // Otherwise, we sort PT_LOAD segments based on the flags. Readonly
3012 // segments come before writable segments. Then writable segments
3013 // with data come before writable segments without data. Then
3014 // executable segments come before non-executable segments. Then
3015 // the unlikely case of a non-readable segment comes before the
3016 // normal case of a readable segment. If there are multiple
3017 // segments with the same type and flags, we require that the
3018 // address be set, and we sort by virtual address and then physical
3020 if ((flags1 & elfcpp::PF_W) != (flags2 & elfcpp::PF_W))
3021 return (flags1 & elfcpp::PF_W) == 0;
3022 if ((flags1 & elfcpp::PF_W) != 0
3023 && seg1->has_any_data_sections() != seg2->has_any_data_sections())
3024 return seg1->has_any_data_sections();
3025 if ((flags1 & elfcpp::PF_X) != (flags2 & elfcpp::PF_X))
3026 return (flags1 & elfcpp::PF_X) != 0;
3027 if ((flags1 & elfcpp::PF_R) != (flags2 & elfcpp::PF_R))
3028 return (flags1 & elfcpp::PF_R) == 0;
3030 // We shouldn't get here--we shouldn't create segments which we
3031 // can't distinguish. Unless of course we are using a weird linker
3032 // script or overlapping --section-start options.
3033 gold_assert(this->script_options_->saw_phdrs_clause()
3034 || parameters->options().any_section_start());
3038 // Increase OFF so that it is congruent to ADDR modulo ABI_PAGESIZE.
3041 align_file_offset(off_t off, uint64_t addr, uint64_t abi_pagesize)
3043 uint64_t unsigned_off = off;
3044 uint64_t aligned_off = ((unsigned_off & ~(abi_pagesize - 1))
3045 | (addr & (abi_pagesize - 1)));
3046 if (aligned_off < unsigned_off)
3047 aligned_off += abi_pagesize;
3051 // Set the file offsets of all the segments, and all the sections they
3052 // contain. They have all been created. LOAD_SEG must be be laid out
3053 // first. Return the offset of the data to follow.
3056 Layout::set_segment_offsets(const Target* target, Output_segment* load_seg,
3057 unsigned int* pshndx)
3059 // Sort them into the final order. We use a stable sort so that we
3060 // don't randomize the order of indistinguishable segments created
3061 // by linker scripts.
3062 std::stable_sort(this->segment_list_.begin(), this->segment_list_.end(),
3063 Layout::Compare_segments(this));
3065 // Find the PT_LOAD segments, and set their addresses and offsets
3066 // and their section's addresses and offsets.
3067 uint64_t start_addr;
3068 if (parameters->options().user_set_Ttext())
3069 start_addr = parameters->options().Ttext();
3070 else if (parameters->options().output_is_position_independent())
3073 start_addr = target->default_text_segment_address();
3075 uint64_t addr = start_addr;
3078 // If LOAD_SEG is NULL, then the file header and segment headers
3079 // will not be loadable. But they still need to be at offset 0 in
3080 // the file. Set their offsets now.
3081 if (load_seg == NULL)
3083 for (Data_list::iterator p = this->special_output_list_.begin();
3084 p != this->special_output_list_.end();
3087 off = align_address(off, (*p)->addralign());
3088 (*p)->set_address_and_file_offset(0, off);
3089 off += (*p)->data_size();
3093 unsigned int increase_relro = this->increase_relro_;
3094 if (this->script_options_->saw_sections_clause())
3097 const bool check_sections = parameters->options().check_sections();
3098 Output_segment* last_load_segment = NULL;
3100 unsigned int shndx_begin = *pshndx;
3101 unsigned int shndx_load_seg = *pshndx;
3103 for (Segment_list::iterator p = this->segment_list_.begin();
3104 p != this->segment_list_.end();
3107 if ((*p)->type() == elfcpp::PT_LOAD)
3109 if (target->isolate_execinstr())
3111 // When we hit the segment that should contain the
3112 // file headers, reset the file offset so we place
3113 // it and subsequent segments appropriately.
3114 // We'll fix up the preceding segments below.
3122 shndx_load_seg = *pshndx;
3128 // Verify that the file headers fall into the first segment.
3129 if (load_seg != NULL && load_seg != *p)
3134 bool are_addresses_set = (*p)->are_addresses_set();
3135 if (are_addresses_set)
3137 // When it comes to setting file offsets, we care about
3138 // the physical address.
3139 addr = (*p)->paddr();
3141 else if (parameters->options().user_set_Ttext()
3142 && ((*p)->flags() & elfcpp::PF_W) == 0)
3144 are_addresses_set = true;
3146 else if (parameters->options().user_set_Tdata()
3147 && ((*p)->flags() & elfcpp::PF_W) != 0
3148 && (!parameters->options().user_set_Tbss()
3149 || (*p)->has_any_data_sections()))
3151 addr = parameters->options().Tdata();
3152 are_addresses_set = true;
3154 else if (parameters->options().user_set_Tbss()
3155 && ((*p)->flags() & elfcpp::PF_W) != 0
3156 && !(*p)->has_any_data_sections())
3158 addr = parameters->options().Tbss();
3159 are_addresses_set = true;
3162 uint64_t orig_addr = addr;
3163 uint64_t orig_off = off;
3165 uint64_t aligned_addr = 0;
3166 uint64_t abi_pagesize = target->abi_pagesize();
3167 uint64_t common_pagesize = target->common_pagesize();
3169 if (!parameters->options().nmagic()
3170 && !parameters->options().omagic())
3171 (*p)->set_minimum_p_align(common_pagesize);
3173 if (!are_addresses_set)
3175 // Skip the address forward one page, maintaining the same
3176 // position within the page. This lets us store both segments
3177 // overlapping on a single page in the file, but the loader will
3178 // put them on different pages in memory. We will revisit this
3179 // decision once we know the size of the segment.
3181 addr = align_address(addr, (*p)->maximum_alignment());
3182 aligned_addr = addr;
3186 // This is the segment that will contain the file
3187 // headers, so its offset will have to be exactly zero.
3188 gold_assert(orig_off == 0);
3190 // If the target wants a fixed minimum distance from the
3191 // text segment to the read-only segment, move up now.
3192 uint64_t min_addr = start_addr + target->rosegment_gap();
3193 if (addr < min_addr)
3196 // But this is not the first segment! To make its
3197 // address congruent with its offset, that address better
3198 // be aligned to the ABI-mandated page size.
3199 addr = align_address(addr, abi_pagesize);
3200 aligned_addr = addr;
3204 if ((addr & (abi_pagesize - 1)) != 0)
3205 addr = addr + abi_pagesize;
3207 off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
3211 if (!parameters->options().nmagic()
3212 && !parameters->options().omagic())
3213 off = align_file_offset(off, addr, abi_pagesize);
3216 // This is -N or -n with a section script which prevents
3217 // us from using a load segment. We need to ensure that
3218 // the file offset is aligned to the alignment of the
3219 // segment. This is because the linker script
3220 // implicitly assumed a zero offset. If we don't align
3221 // here, then the alignment of the sections in the
3222 // linker script may not match the alignment of the
3223 // sections in the set_section_addresses call below,
3224 // causing an error about dot moving backward.
3225 off = align_address(off, (*p)->maximum_alignment());
3228 unsigned int shndx_hold = *pshndx;
3229 bool has_relro = false;
3230 uint64_t new_addr = (*p)->set_section_addresses(this, false, addr,
3235 // Now that we know the size of this segment, we may be able
3236 // to save a page in memory, at the cost of wasting some
3237 // file space, by instead aligning to the start of a new
3238 // page. Here we use the real machine page size rather than
3239 // the ABI mandated page size. If the segment has been
3240 // aligned so that the relro data ends at a page boundary,
3241 // we do not try to realign it.
3243 if (!are_addresses_set
3245 && aligned_addr != addr
3246 && !parameters->incremental())
3248 uint64_t first_off = (common_pagesize
3250 & (common_pagesize - 1)));
3251 uint64_t last_off = new_addr & (common_pagesize - 1);
3254 && ((aligned_addr & ~ (common_pagesize - 1))
3255 != (new_addr & ~ (common_pagesize - 1)))
3256 && first_off + last_off <= common_pagesize)
3258 *pshndx = shndx_hold;
3259 addr = align_address(aligned_addr, common_pagesize);
3260 addr = align_address(addr, (*p)->maximum_alignment());
3261 off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
3262 off = align_file_offset(off, addr, abi_pagesize);
3264 increase_relro = this->increase_relro_;
3265 if (this->script_options_->saw_sections_clause())
3269 new_addr = (*p)->set_section_addresses(this, true, addr,
3278 // Implement --check-sections. We know that the segments
3279 // are sorted by LMA.
3280 if (check_sections && last_load_segment != NULL)
3282 gold_assert(last_load_segment->paddr() <= (*p)->paddr());
3283 if (last_load_segment->paddr() + last_load_segment->memsz()
3286 unsigned long long lb1 = last_load_segment->paddr();
3287 unsigned long long le1 = lb1 + last_load_segment->memsz();
3288 unsigned long long lb2 = (*p)->paddr();
3289 unsigned long long le2 = lb2 + (*p)->memsz();
3290 gold_error(_("load segment overlap [0x%llx -> 0x%llx] and "
3291 "[0x%llx -> 0x%llx]"),
3292 lb1, le1, lb2, le2);
3295 last_load_segment = *p;
3299 if (load_seg != NULL && target->isolate_execinstr())
3301 // Process the early segments again, setting their file offsets
3302 // so they land after the segments starting at LOAD_SEG.
3303 off = align_file_offset(off, 0, target->abi_pagesize());
3305 for (Segment_list::iterator p = this->segment_list_.begin();
3309 if ((*p)->type() == elfcpp::PT_LOAD)
3311 // We repeat the whole job of assigning addresses and
3312 // offsets, but we really only want to change the offsets and
3313 // must ensure that the addresses all come out the same as
3314 // they did the first time through.
3315 bool has_relro = false;
3316 const uint64_t old_addr = (*p)->vaddr();
3317 const uint64_t old_end = old_addr + (*p)->memsz();
3318 uint64_t new_addr = (*p)->set_section_addresses(this, true,
3324 gold_assert(new_addr == old_end);
3328 gold_assert(shndx_begin == shndx_load_seg);
3331 // Handle the non-PT_LOAD segments, setting their offsets from their
3332 // section's offsets.
3333 for (Segment_list::iterator p = this->segment_list_.begin();
3334 p != this->segment_list_.end();
3337 if ((*p)->type() != elfcpp::PT_LOAD)
3338 (*p)->set_offset((*p)->type() == elfcpp::PT_GNU_RELRO
3343 // Set the TLS offsets for each section in the PT_TLS segment.
3344 if (this->tls_segment_ != NULL)
3345 this->tls_segment_->set_tls_offsets();
3350 // Set the offsets of all the allocated sections when doing a
3351 // relocatable link. This does the same jobs as set_segment_offsets,
3352 // only for a relocatable link.
3355 Layout::set_relocatable_section_offsets(Output_data* file_header,
3356 unsigned int* pshndx)
3360 file_header->set_address_and_file_offset(0, 0);
3361 off += file_header->data_size();
3363 for (Section_list::iterator p = this->section_list_.begin();
3364 p != this->section_list_.end();
3367 // We skip unallocated sections here, except that group sections
3368 // have to come first.
3369 if (((*p)->flags() & elfcpp::SHF_ALLOC) == 0
3370 && (*p)->type() != elfcpp::SHT_GROUP)
3373 off = align_address(off, (*p)->addralign());
3375 // The linker script might have set the address.
3376 if (!(*p)->is_address_valid())
3377 (*p)->set_address(0);
3378 (*p)->set_file_offset(off);
3379 (*p)->finalize_data_size();
3380 off += (*p)->data_size();
3382 (*p)->set_out_shndx(*pshndx);
3389 // Set the file offset of all the sections not associated with a
3393 Layout::set_section_offsets(off_t off, Layout::Section_offset_pass pass)
3395 off_t startoff = off;
3398 for (Section_list::iterator p = this->unattached_section_list_.begin();
3399 p != this->unattached_section_list_.end();
3402 // The symtab section is handled in create_symtab_sections.
3403 if (*p == this->symtab_section_)
3406 // If we've already set the data size, don't set it again.
3407 if ((*p)->is_offset_valid() && (*p)->is_data_size_valid())
3410 if (pass == BEFORE_INPUT_SECTIONS_PASS
3411 && (*p)->requires_postprocessing())
3413 (*p)->create_postprocessing_buffer();
3414 this->any_postprocessing_sections_ = true;
3417 if (pass == BEFORE_INPUT_SECTIONS_PASS
3418 && (*p)->after_input_sections())
3420 else if (pass == POSTPROCESSING_SECTIONS_PASS
3421 && (!(*p)->after_input_sections()
3422 || (*p)->type() == elfcpp::SHT_STRTAB))
3424 else if (pass == STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
3425 && (!(*p)->after_input_sections()
3426 || (*p)->type() != elfcpp::SHT_STRTAB))
3429 if (!parameters->incremental_update())
3431 off = align_address(off, (*p)->addralign());
3432 (*p)->set_file_offset(off);
3433 (*p)->finalize_data_size();
3437 // Incremental update: allocate file space from free list.
3438 (*p)->pre_finalize_data_size();
3439 off_t current_size = (*p)->current_data_size();
3440 off = this->allocate(current_size, (*p)->addralign(), startoff);
3443 if (is_debugging_enabled(DEBUG_INCREMENTAL))
3444 this->free_list_.dump();
3445 gold_assert((*p)->output_section() != NULL);
3446 gold_fallback(_("out of patch space for section %s; "
3447 "relink with --incremental-full"),
3448 (*p)->output_section()->name());
3450 (*p)->set_file_offset(off);
3451 (*p)->finalize_data_size();
3452 if ((*p)->data_size() > current_size)
3454 gold_assert((*p)->output_section() != NULL);
3455 gold_fallback(_("%s: section changed size; "
3456 "relink with --incremental-full"),
3457 (*p)->output_section()->name());
3459 gold_debug(DEBUG_INCREMENTAL,
3460 "set_section_offsets: %08lx %08lx %s",
3461 static_cast<long>(off),
3462 static_cast<long>((*p)->data_size()),
3463 ((*p)->output_section() != NULL
3464 ? (*p)->output_section()->name() : "(special)"));
3467 off += (*p)->data_size();
3471 // At this point the name must be set.
3472 if (pass != STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS)
3473 this->namepool_.add((*p)->name(), false, NULL);
3478 // Set the section indexes of all the sections not associated with a
3482 Layout::set_section_indexes(unsigned int shndx)
3484 for (Section_list::iterator p = this->unattached_section_list_.begin();
3485 p != this->unattached_section_list_.end();
3488 if (!(*p)->has_out_shndx())
3490 (*p)->set_out_shndx(shndx);
3497 // Set the section addresses according to the linker script. This is
3498 // only called when we see a SECTIONS clause. This returns the
3499 // program segment which should hold the file header and segment
3500 // headers, if any. It will return NULL if they should not be in a
3504 Layout::set_section_addresses_from_script(Symbol_table* symtab)
3506 Script_sections* ss = this->script_options_->script_sections();
3507 gold_assert(ss->saw_sections_clause());
3508 return this->script_options_->set_section_addresses(symtab, this);
3511 // Place the orphan sections in the linker script.
3514 Layout::place_orphan_sections_in_script()
3516 Script_sections* ss = this->script_options_->script_sections();
3517 gold_assert(ss->saw_sections_clause());
3519 // Place each orphaned output section in the script.
3520 for (Section_list::iterator p = this->section_list_.begin();
3521 p != this->section_list_.end();
3524 if (!(*p)->found_in_sections_clause())
3525 ss->place_orphan(*p);
3529 // Count the local symbols in the regular symbol table and the dynamic
3530 // symbol table, and build the respective string pools.
3533 Layout::count_local_symbols(const Task* task,
3534 const Input_objects* input_objects)
3536 // First, figure out an upper bound on the number of symbols we'll
3537 // be inserting into each pool. This helps us create the pools with
3538 // the right size, to avoid unnecessary hashtable resizing.
3539 unsigned int symbol_count = 0;
3540 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
3541 p != input_objects->relobj_end();
3543 symbol_count += (*p)->local_symbol_count();
3545 // Go from "upper bound" to "estimate." We overcount for two
3546 // reasons: we double-count symbols that occur in more than one
3547 // object file, and we count symbols that are dropped from the
3548 // output. Add it all together and assume we overcount by 100%.
3551 // We assume all symbols will go into both the sympool and dynpool.
3552 this->sympool_.reserve(symbol_count);
3553 this->dynpool_.reserve(symbol_count);
3555 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
3556 p != input_objects->relobj_end();
3559 Task_lock_obj<Object> tlo(task, *p);
3560 (*p)->count_local_symbols(&this->sympool_, &this->dynpool_);
3564 // Create the symbol table sections. Here we also set the final
3565 // values of the symbols. At this point all the loadable sections are
3566 // fully laid out. SHNUM is the number of sections so far.
3569 Layout::create_symtab_sections(const Input_objects* input_objects,
3570 Symbol_table* symtab,
3576 if (parameters->target().get_size() == 32)
3578 symsize = elfcpp::Elf_sizes<32>::sym_size;
3581 else if (parameters->target().get_size() == 64)
3583 symsize = elfcpp::Elf_sizes<64>::sym_size;
3589 // Compute file offsets relative to the start of the symtab section.
3592 // Save space for the dummy symbol at the start of the section. We
3593 // never bother to write this out--it will just be left as zero.
3595 unsigned int local_symbol_index = 1;
3597 // Add STT_SECTION symbols for each Output section which needs one.
3598 for (Section_list::iterator p = this->section_list_.begin();
3599 p != this->section_list_.end();
3602 if (!(*p)->needs_symtab_index())
3603 (*p)->set_symtab_index(-1U);
3606 (*p)->set_symtab_index(local_symbol_index);
3607 ++local_symbol_index;
3612 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
3613 p != input_objects->relobj_end();
3616 unsigned int index = (*p)->finalize_local_symbols(local_symbol_index,
3618 off += (index - local_symbol_index) * symsize;
3619 local_symbol_index = index;
3622 unsigned int local_symcount = local_symbol_index;
3623 gold_assert(static_cast<off_t>(local_symcount * symsize) == off);
3626 size_t dyn_global_index;
3628 if (this->dynsym_section_ == NULL)
3631 dyn_global_index = 0;
3636 dyn_global_index = this->dynsym_section_->info();
3637 off_t locsize = dyn_global_index * this->dynsym_section_->entsize();
3638 dynoff = this->dynsym_section_->offset() + locsize;
3639 dyncount = (this->dynsym_section_->data_size() - locsize) / symsize;
3640 gold_assert(static_cast<off_t>(dyncount * symsize)
3641 == this->dynsym_section_->data_size() - locsize);
3644 off_t global_off = off;
3645 off = symtab->finalize(off, dynoff, dyn_global_index, dyncount,
3646 &this->sympool_, &local_symcount);
3648 if (!parameters->options().strip_all())
3650 this->sympool_.set_string_offsets();
3652 const char* symtab_name = this->namepool_.add(".symtab", false, NULL);
3653 Output_section* osymtab = this->make_output_section(symtab_name,
3657 this->symtab_section_ = osymtab;
3659 Output_section_data* pos = new Output_data_fixed_space(off, align,
3661 osymtab->add_output_section_data(pos);
3663 // We generate a .symtab_shndx section if we have more than
3664 // SHN_LORESERVE sections. Technically it is possible that we
3665 // don't need one, because it is possible that there are no
3666 // symbols in any of sections with indexes larger than
3667 // SHN_LORESERVE. That is probably unusual, though, and it is
3668 // easier to always create one than to compute section indexes
3669 // twice (once here, once when writing out the symbols).
3670 if (shnum >= elfcpp::SHN_LORESERVE)
3672 const char* symtab_xindex_name = this->namepool_.add(".symtab_shndx",
3674 Output_section* osymtab_xindex =
3675 this->make_output_section(symtab_xindex_name,
3676 elfcpp::SHT_SYMTAB_SHNDX, 0,
3677 ORDER_INVALID, false);
3679 size_t symcount = off / symsize;
3680 this->symtab_xindex_ = new Output_symtab_xindex(symcount);
3682 osymtab_xindex->add_output_section_data(this->symtab_xindex_);
3684 osymtab_xindex->set_link_section(osymtab);
3685 osymtab_xindex->set_addralign(4);
3686 osymtab_xindex->set_entsize(4);
3688 osymtab_xindex->set_after_input_sections();
3690 // This tells the driver code to wait until the symbol table
3691 // has written out before writing out the postprocessing
3692 // sections, including the .symtab_shndx section.
3693 this->any_postprocessing_sections_ = true;
3696 const char* strtab_name = this->namepool_.add(".strtab", false, NULL);
3697 Output_section* ostrtab = this->make_output_section(strtab_name,
3702 Output_section_data* pstr = new Output_data_strtab(&this->sympool_);
3703 ostrtab->add_output_section_data(pstr);
3706 if (!parameters->incremental_update())
3707 symtab_off = align_address(*poff, align);
3710 symtab_off = this->allocate(off, align, *poff);
3712 gold_fallback(_("out of patch space for symbol table; "
3713 "relink with --incremental-full"));
3714 gold_debug(DEBUG_INCREMENTAL,
3715 "create_symtab_sections: %08lx %08lx .symtab",
3716 static_cast<long>(symtab_off),
3717 static_cast<long>(off));
3720 symtab->set_file_offset(symtab_off + global_off);
3721 osymtab->set_file_offset(symtab_off);
3722 osymtab->finalize_data_size();
3723 osymtab->set_link_section(ostrtab);
3724 osymtab->set_info(local_symcount);
3725 osymtab->set_entsize(symsize);
3727 if (symtab_off + off > *poff)
3728 *poff = symtab_off + off;
3732 // Create the .shstrtab section, which holds the names of the
3733 // sections. At the time this is called, we have created all the
3734 // output sections except .shstrtab itself.
3737 Layout::create_shstrtab()
3739 // FIXME: We don't need to create a .shstrtab section if we are
3740 // stripping everything.
3742 const char* name = this->namepool_.add(".shstrtab", false, NULL);
3744 Output_section* os = this->make_output_section(name, elfcpp::SHT_STRTAB, 0,
3745 ORDER_INVALID, false);
3747 if (strcmp(parameters->options().compress_debug_sections(), "none") != 0)
3749 // We can't write out this section until we've set all the
3750 // section names, and we don't set the names of compressed
3751 // output sections until relocations are complete. FIXME: With
3752 // the current names we use, this is unnecessary.
3753 os->set_after_input_sections();
3756 Output_section_data* posd = new Output_data_strtab(&this->namepool_);
3757 os->add_output_section_data(posd);
3762 // Create the section headers. SIZE is 32 or 64. OFF is the file
3766 Layout::create_shdrs(const Output_section* shstrtab_section, off_t* poff)
3768 Output_section_headers* oshdrs;
3769 oshdrs = new Output_section_headers(this,
3770 &this->segment_list_,
3771 &this->section_list_,
3772 &this->unattached_section_list_,
3776 if (!parameters->incremental_update())
3777 off = align_address(*poff, oshdrs->addralign());
3780 oshdrs->pre_finalize_data_size();
3781 off = this->allocate(oshdrs->data_size(), oshdrs->addralign(), *poff);
3783 gold_fallback(_("out of patch space for section header table; "
3784 "relink with --incremental-full"));
3785 gold_debug(DEBUG_INCREMENTAL,
3786 "create_shdrs: %08lx %08lx (section header table)",
3787 static_cast<long>(off),
3788 static_cast<long>(off + oshdrs->data_size()));
3790 oshdrs->set_address_and_file_offset(0, off);
3791 off += oshdrs->data_size();
3794 this->section_headers_ = oshdrs;
3797 // Count the allocated sections.
3800 Layout::allocated_output_section_count() const
3802 size_t section_count = 0;
3803 for (Segment_list::const_iterator p = this->segment_list_.begin();
3804 p != this->segment_list_.end();
3806 section_count += (*p)->output_section_count();
3807 return section_count;
3810 // Create the dynamic symbol table.
3813 Layout::create_dynamic_symtab(const Input_objects* input_objects,
3814 Symbol_table* symtab,
3815 Output_section** pdynstr,
3816 unsigned int* plocal_dynamic_count,
3817 std::vector<Symbol*>* pdynamic_symbols,
3818 Versions* pversions)
3820 // Count all the symbols in the dynamic symbol table, and set the
3821 // dynamic symbol indexes.
3823 // Skip symbol 0, which is always all zeroes.
3824 unsigned int index = 1;
3826 // Add STT_SECTION symbols for each Output section which needs one.
3827 for (Section_list::iterator p = this->section_list_.begin();
3828 p != this->section_list_.end();
3831 if (!(*p)->needs_dynsym_index())
3832 (*p)->set_dynsym_index(-1U);
3835 (*p)->set_dynsym_index(index);
3840 // Count the local symbols that need to go in the dynamic symbol table,
3841 // and set the dynamic symbol indexes.
3842 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
3843 p != input_objects->relobj_end();
3846 unsigned int new_index = (*p)->set_local_dynsym_indexes(index);
3850 unsigned int local_symcount = index;
3851 *plocal_dynamic_count = local_symcount;
3853 index = symtab->set_dynsym_indexes(index, pdynamic_symbols,
3854 &this->dynpool_, pversions);
3858 const int size = parameters->target().get_size();
3861 symsize = elfcpp::Elf_sizes<32>::sym_size;
3864 else if (size == 64)
3866 symsize = elfcpp::Elf_sizes<64>::sym_size;
3872 // Create the dynamic symbol table section.
3874 Output_section* dynsym = this->choose_output_section(NULL, ".dynsym",
3878 ORDER_DYNAMIC_LINKER,
3881 // Check for NULL as a linker script may discard .dynsym.
3884 Output_section_data* odata = new Output_data_fixed_space(index * symsize,
3887 dynsym->add_output_section_data(odata);
3889 dynsym->set_info(local_symcount);
3890 dynsym->set_entsize(symsize);
3891 dynsym->set_addralign(align);
3893 this->dynsym_section_ = dynsym;
3896 Output_data_dynamic* const odyn = this->dynamic_data_;
3899 odyn->add_section_address(elfcpp::DT_SYMTAB, dynsym);
3900 odyn->add_constant(elfcpp::DT_SYMENT, symsize);
3903 // If there are more than SHN_LORESERVE allocated sections, we
3904 // create a .dynsym_shndx section. It is possible that we don't
3905 // need one, because it is possible that there are no dynamic
3906 // symbols in any of the sections with indexes larger than
3907 // SHN_LORESERVE. This is probably unusual, though, and at this
3908 // time we don't know the actual section indexes so it is
3909 // inconvenient to check.
3910 if (this->allocated_output_section_count() >= elfcpp::SHN_LORESERVE)
3912 Output_section* dynsym_xindex =
3913 this->choose_output_section(NULL, ".dynsym_shndx",
3914 elfcpp::SHT_SYMTAB_SHNDX,
3916 false, ORDER_DYNAMIC_LINKER, false);
3918 if (dynsym_xindex != NULL)
3920 this->dynsym_xindex_ = new Output_symtab_xindex(index);
3922 dynsym_xindex->add_output_section_data(this->dynsym_xindex_);
3924 dynsym_xindex->set_link_section(dynsym);
3925 dynsym_xindex->set_addralign(4);
3926 dynsym_xindex->set_entsize(4);
3928 dynsym_xindex->set_after_input_sections();
3930 // This tells the driver code to wait until the symbol table
3931 // has written out before writing out the postprocessing
3932 // sections, including the .dynsym_shndx section.
3933 this->any_postprocessing_sections_ = true;
3937 // Create the dynamic string table section.
3939 Output_section* dynstr = this->choose_output_section(NULL, ".dynstr",
3943 ORDER_DYNAMIC_LINKER,
3948 Output_section_data* strdata = new Output_data_strtab(&this->dynpool_);
3949 dynstr->add_output_section_data(strdata);
3952 dynsym->set_link_section(dynstr);
3953 if (this->dynamic_section_ != NULL)
3954 this->dynamic_section_->set_link_section(dynstr);
3958 odyn->add_section_address(elfcpp::DT_STRTAB, dynstr);
3959 odyn->add_section_size(elfcpp::DT_STRSZ, dynstr);
3965 // Create the hash tables.
3967 if (strcmp(parameters->options().hash_style(), "sysv") == 0
3968 || strcmp(parameters->options().hash_style(), "both") == 0)
3970 unsigned char* phash;
3971 unsigned int hashlen;
3972 Dynobj::create_elf_hash_table(*pdynamic_symbols, local_symcount,
3975 Output_section* hashsec =
3976 this->choose_output_section(NULL, ".hash", elfcpp::SHT_HASH,
3977 elfcpp::SHF_ALLOC, false,
3978 ORDER_DYNAMIC_LINKER, false);
3980 Output_section_data* hashdata = new Output_data_const_buffer(phash,
3984 if (hashsec != NULL && hashdata != NULL)
3985 hashsec->add_output_section_data(hashdata);
3987 if (hashsec != NULL)
3990 hashsec->set_link_section(dynsym);
3991 hashsec->set_entsize(4);
3995 odyn->add_section_address(elfcpp::DT_HASH, hashsec);
3998 if (strcmp(parameters->options().hash_style(), "gnu") == 0
3999 || strcmp(parameters->options().hash_style(), "both") == 0)
4001 unsigned char* phash;
4002 unsigned int hashlen;
4003 Dynobj::create_gnu_hash_table(*pdynamic_symbols, local_symcount,
4006 Output_section* hashsec =
4007 this->choose_output_section(NULL, ".gnu.hash", elfcpp::SHT_GNU_HASH,
4008 elfcpp::SHF_ALLOC, false,
4009 ORDER_DYNAMIC_LINKER, false);
4011 Output_section_data* hashdata = new Output_data_const_buffer(phash,
4015 if (hashsec != NULL && hashdata != NULL)
4016 hashsec->add_output_section_data(hashdata);
4018 if (hashsec != NULL)
4021 hashsec->set_link_section(dynsym);
4023 // For a 64-bit target, the entries in .gnu.hash do not have
4024 // a uniform size, so we only set the entry size for a
4026 if (parameters->target().get_size() == 32)
4027 hashsec->set_entsize(4);
4030 odyn->add_section_address(elfcpp::DT_GNU_HASH, hashsec);
4035 // Assign offsets to each local portion of the dynamic symbol table.
4038 Layout::assign_local_dynsym_offsets(const Input_objects* input_objects)
4040 Output_section* dynsym = this->dynsym_section_;
4044 off_t off = dynsym->offset();
4046 // Skip the dummy symbol at the start of the section.
4047 off += dynsym->entsize();
4049 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
4050 p != input_objects->relobj_end();
4053 unsigned int count = (*p)->set_local_dynsym_offset(off);
4054 off += count * dynsym->entsize();
4058 // Create the version sections.
4061 Layout::create_version_sections(const Versions* versions,
4062 const Symbol_table* symtab,
4063 unsigned int local_symcount,
4064 const std::vector<Symbol*>& dynamic_symbols,
4065 const Output_section* dynstr)
4067 if (!versions->any_defs() && !versions->any_needs())
4070 switch (parameters->size_and_endianness())
4072 #ifdef HAVE_TARGET_32_LITTLE
4073 case Parameters::TARGET_32_LITTLE:
4074 this->sized_create_version_sections<32, false>(versions, symtab,
4076 dynamic_symbols, dynstr);
4079 #ifdef HAVE_TARGET_32_BIG
4080 case Parameters::TARGET_32_BIG:
4081 this->sized_create_version_sections<32, true>(versions, symtab,
4083 dynamic_symbols, dynstr);
4086 #ifdef HAVE_TARGET_64_LITTLE
4087 case Parameters::TARGET_64_LITTLE:
4088 this->sized_create_version_sections<64, false>(versions, symtab,
4090 dynamic_symbols, dynstr);
4093 #ifdef HAVE_TARGET_64_BIG
4094 case Parameters::TARGET_64_BIG:
4095 this->sized_create_version_sections<64, true>(versions, symtab,
4097 dynamic_symbols, dynstr);
4105 // Create the version sections, sized version.
4107 template<int size, bool big_endian>
4109 Layout::sized_create_version_sections(
4110 const Versions* versions,
4111 const Symbol_table* symtab,
4112 unsigned int local_symcount,
4113 const std::vector<Symbol*>& dynamic_symbols,
4114 const Output_section* dynstr)
4116 Output_section* vsec = this->choose_output_section(NULL, ".gnu.version",
4117 elfcpp::SHT_GNU_versym,
4120 ORDER_DYNAMIC_LINKER,
4123 // Check for NULL since a linker script may discard this section.
4126 unsigned char* vbuf;
4128 versions->symbol_section_contents<size, big_endian>(symtab,
4134 Output_section_data* vdata = new Output_data_const_buffer(vbuf, vsize, 2,
4137 vsec->add_output_section_data(vdata);
4138 vsec->set_entsize(2);
4139 vsec->set_link_section(this->dynsym_section_);
4142 Output_data_dynamic* const odyn = this->dynamic_data_;
4143 if (odyn != NULL && vsec != NULL)
4144 odyn->add_section_address(elfcpp::DT_VERSYM, vsec);
4146 if (versions->any_defs())
4148 Output_section* vdsec;
4149 vdsec = this->choose_output_section(NULL, ".gnu.version_d",
4150 elfcpp::SHT_GNU_verdef,
4152 false, ORDER_DYNAMIC_LINKER, false);
4156 unsigned char* vdbuf;
4157 unsigned int vdsize;
4158 unsigned int vdentries;
4159 versions->def_section_contents<size, big_endian>(&this->dynpool_,
4163 Output_section_data* vddata =
4164 new Output_data_const_buffer(vdbuf, vdsize, 4, "** version defs");
4166 vdsec->add_output_section_data(vddata);
4167 vdsec->set_link_section(dynstr);
4168 vdsec->set_info(vdentries);
4172 odyn->add_section_address(elfcpp::DT_VERDEF, vdsec);
4173 odyn->add_constant(elfcpp::DT_VERDEFNUM, vdentries);
4178 if (versions->any_needs())
4180 Output_section* vnsec;
4181 vnsec = this->choose_output_section(NULL, ".gnu.version_r",
4182 elfcpp::SHT_GNU_verneed,
4184 false, ORDER_DYNAMIC_LINKER, false);
4188 unsigned char* vnbuf;
4189 unsigned int vnsize;
4190 unsigned int vnentries;
4191 versions->need_section_contents<size, big_endian>(&this->dynpool_,
4195 Output_section_data* vndata =
4196 new Output_data_const_buffer(vnbuf, vnsize, 4, "** version refs");
4198 vnsec->add_output_section_data(vndata);
4199 vnsec->set_link_section(dynstr);
4200 vnsec->set_info(vnentries);
4204 odyn->add_section_address(elfcpp::DT_VERNEED, vnsec);
4205 odyn->add_constant(elfcpp::DT_VERNEEDNUM, vnentries);
4211 // Create the .interp section and PT_INTERP segment.
4214 Layout::create_interp(const Target* target)
4216 gold_assert(this->interp_segment_ == NULL);
4218 const char* interp = parameters->options().dynamic_linker();
4221 interp = target->dynamic_linker();
4222 gold_assert(interp != NULL);
4225 size_t len = strlen(interp) + 1;
4227 Output_section_data* odata = new Output_data_const(interp, len, 1);
4229 Output_section* osec = this->choose_output_section(NULL, ".interp",
4230 elfcpp::SHT_PROGBITS,
4232 false, ORDER_INTERP,
4235 osec->add_output_section_data(odata);
4238 // Add dynamic tags for the PLT and the dynamic relocs. This is
4239 // called by the target-specific code. This does nothing if not doing
4242 // USE_REL is true for REL relocs rather than RELA relocs.
4244 // If PLT_GOT is not NULL, then DT_PLTGOT points to it.
4246 // If PLT_REL is not NULL, it is used for DT_PLTRELSZ, and DT_JMPREL,
4247 // and we also set DT_PLTREL. We use PLT_REL's output section, since
4248 // some targets have multiple reloc sections in PLT_REL.
4250 // If DYN_REL is not NULL, it is used for DT_REL/DT_RELA,
4251 // DT_RELSZ/DT_RELASZ, DT_RELENT/DT_RELAENT. Again we use the output
4254 // If ADD_DEBUG is true, we add a DT_DEBUG entry when generating an
4258 Layout::add_target_dynamic_tags(bool use_rel, const Output_data* plt_got,
4259 const Output_data* plt_rel,
4260 const Output_data_reloc_generic* dyn_rel,
4261 bool add_debug, bool dynrel_includes_plt)
4263 Output_data_dynamic* odyn = this->dynamic_data_;
4267 if (plt_got != NULL && plt_got->output_section() != NULL)
4268 odyn->add_section_address(elfcpp::DT_PLTGOT, plt_got);
4270 if (plt_rel != NULL && plt_rel->output_section() != NULL)
4272 odyn->add_section_size(elfcpp::DT_PLTRELSZ, plt_rel->output_section());
4273 odyn->add_section_address(elfcpp::DT_JMPREL, plt_rel->output_section());
4274 odyn->add_constant(elfcpp::DT_PLTREL,
4275 use_rel ? elfcpp::DT_REL : elfcpp::DT_RELA);
4278 if (dyn_rel != NULL && dyn_rel->output_section() != NULL)
4280 odyn->add_section_address(use_rel ? elfcpp::DT_REL : elfcpp::DT_RELA,
4281 dyn_rel->output_section());
4283 && plt_rel->output_section() != NULL
4284 && dynrel_includes_plt)
4285 odyn->add_section_size(use_rel ? elfcpp::DT_RELSZ : elfcpp::DT_RELASZ,
4286 dyn_rel->output_section(),
4287 plt_rel->output_section());
4289 odyn->add_section_size(use_rel ? elfcpp::DT_RELSZ : elfcpp::DT_RELASZ,
4290 dyn_rel->output_section());
4291 const int size = parameters->target().get_size();
4296 rel_tag = elfcpp::DT_RELENT;
4298 rel_size = Reloc_types<elfcpp::SHT_REL, 32, false>::reloc_size;
4299 else if (size == 64)
4300 rel_size = Reloc_types<elfcpp::SHT_REL, 64, false>::reloc_size;
4306 rel_tag = elfcpp::DT_RELAENT;
4308 rel_size = Reloc_types<elfcpp::SHT_RELA, 32, false>::reloc_size;
4309 else if (size == 64)
4310 rel_size = Reloc_types<elfcpp::SHT_RELA, 64, false>::reloc_size;
4314 odyn->add_constant(rel_tag, rel_size);
4316 if (parameters->options().combreloc())
4318 size_t c = dyn_rel->relative_reloc_count();
4320 odyn->add_constant((use_rel
4321 ? elfcpp::DT_RELCOUNT
4322 : elfcpp::DT_RELACOUNT),
4327 if (add_debug && !parameters->options().shared())
4329 // The value of the DT_DEBUG tag is filled in by the dynamic
4330 // linker at run time, and used by the debugger.
4331 odyn->add_constant(elfcpp::DT_DEBUG, 0);
4335 // Finish the .dynamic section and PT_DYNAMIC segment.
4338 Layout::finish_dynamic_section(const Input_objects* input_objects,
4339 const Symbol_table* symtab)
4341 if (!this->script_options_->saw_phdrs_clause()
4342 && this->dynamic_section_ != NULL)
4344 Output_segment* oseg = this->make_output_segment(elfcpp::PT_DYNAMIC,
4347 oseg->add_output_section_to_nonload(this->dynamic_section_,
4348 elfcpp::PF_R | elfcpp::PF_W);
4351 Output_data_dynamic* const odyn = this->dynamic_data_;
4355 for (Input_objects::Dynobj_iterator p = input_objects->dynobj_begin();
4356 p != input_objects->dynobj_end();
4359 if (!(*p)->is_needed() && (*p)->as_needed())
4361 // This dynamic object was linked with --as-needed, but it
4366 odyn->add_string(elfcpp::DT_NEEDED, (*p)->soname());
4369 if (parameters->options().shared())
4371 const char* soname = parameters->options().soname();
4373 odyn->add_string(elfcpp::DT_SONAME, soname);
4376 Symbol* sym = symtab->lookup(parameters->options().init());
4377 if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj())
4378 odyn->add_symbol(elfcpp::DT_INIT, sym);
4380 sym = symtab->lookup(parameters->options().fini());
4381 if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj())
4382 odyn->add_symbol(elfcpp::DT_FINI, sym);
4384 // Look for .init_array, .preinit_array and .fini_array by checking
4386 for(Layout::Section_list::const_iterator p = this->section_list_.begin();
4387 p != this->section_list_.end();
4389 switch((*p)->type())
4391 case elfcpp::SHT_FINI_ARRAY:
4392 odyn->add_section_address(elfcpp::DT_FINI_ARRAY, *p);
4393 odyn->add_section_size(elfcpp::DT_FINI_ARRAYSZ, *p);
4395 case elfcpp::SHT_INIT_ARRAY:
4396 odyn->add_section_address(elfcpp::DT_INIT_ARRAY, *p);
4397 odyn->add_section_size(elfcpp::DT_INIT_ARRAYSZ, *p);
4399 case elfcpp::SHT_PREINIT_ARRAY:
4400 odyn->add_section_address(elfcpp::DT_PREINIT_ARRAY, *p);
4401 odyn->add_section_size(elfcpp::DT_PREINIT_ARRAYSZ, *p);
4407 // Add a DT_RPATH entry if needed.
4408 const General_options::Dir_list& rpath(parameters->options().rpath());
4411 std::string rpath_val;
4412 for (General_options::Dir_list::const_iterator p = rpath.begin();
4416 if (rpath_val.empty())
4417 rpath_val = p->name();
4420 // Eliminate duplicates.
4421 General_options::Dir_list::const_iterator q;
4422 for (q = rpath.begin(); q != p; ++q)
4423 if (q->name() == p->name())
4428 rpath_val += p->name();
4433 odyn->add_string(elfcpp::DT_RPATH, rpath_val);
4434 if (parameters->options().enable_new_dtags())
4435 odyn->add_string(elfcpp::DT_RUNPATH, rpath_val);
4438 // Look for text segments that have dynamic relocations.
4439 bool have_textrel = false;
4440 if (!this->script_options_->saw_sections_clause())
4442 for (Segment_list::const_iterator p = this->segment_list_.begin();
4443 p != this->segment_list_.end();
4446 if ((*p)->type() == elfcpp::PT_LOAD
4447 && ((*p)->flags() & elfcpp::PF_W) == 0
4448 && (*p)->has_dynamic_reloc())
4450 have_textrel = true;
4457 // We don't know the section -> segment mapping, so we are
4458 // conservative and just look for readonly sections with
4459 // relocations. If those sections wind up in writable segments,
4460 // then we have created an unnecessary DT_TEXTREL entry.
4461 for (Section_list::const_iterator p = this->section_list_.begin();
4462 p != this->section_list_.end();
4465 if (((*p)->flags() & elfcpp::SHF_ALLOC) != 0
4466 && ((*p)->flags() & elfcpp::SHF_WRITE) == 0
4467 && (*p)->has_dynamic_reloc())
4469 have_textrel = true;
4475 if (parameters->options().filter() != NULL)
4476 odyn->add_string(elfcpp::DT_FILTER, parameters->options().filter());
4477 if (parameters->options().any_auxiliary())
4479 for (options::String_set::const_iterator p =
4480 parameters->options().auxiliary_begin();
4481 p != parameters->options().auxiliary_end();
4483 odyn->add_string(elfcpp::DT_AUXILIARY, *p);
4486 // Add a DT_FLAGS entry if necessary.
4487 unsigned int flags = 0;
4490 // Add a DT_TEXTREL for compatibility with older loaders.
4491 odyn->add_constant(elfcpp::DT_TEXTREL, 0);
4492 flags |= elfcpp::DF_TEXTREL;
4494 if (parameters->options().text())
4495 gold_error(_("read-only segment has dynamic relocations"));
4496 else if (parameters->options().warn_shared_textrel()
4497 && parameters->options().shared())
4498 gold_warning(_("shared library text segment is not shareable"));
4500 if (parameters->options().shared() && this->has_static_tls())
4501 flags |= elfcpp::DF_STATIC_TLS;
4502 if (parameters->options().origin())
4503 flags |= elfcpp::DF_ORIGIN;
4504 if (parameters->options().Bsymbolic())
4506 flags |= elfcpp::DF_SYMBOLIC;
4507 // Add DT_SYMBOLIC for compatibility with older loaders.
4508 odyn->add_constant(elfcpp::DT_SYMBOLIC, 0);
4510 if (parameters->options().now())
4511 flags |= elfcpp::DF_BIND_NOW;
4513 odyn->add_constant(elfcpp::DT_FLAGS, flags);
4516 if (parameters->options().initfirst())
4517 flags |= elfcpp::DF_1_INITFIRST;
4518 if (parameters->options().interpose())
4519 flags |= elfcpp::DF_1_INTERPOSE;
4520 if (parameters->options().loadfltr())
4521 flags |= elfcpp::DF_1_LOADFLTR;
4522 if (parameters->options().nodefaultlib())
4523 flags |= elfcpp::DF_1_NODEFLIB;
4524 if (parameters->options().nodelete())
4525 flags |= elfcpp::DF_1_NODELETE;
4526 if (parameters->options().nodlopen())
4527 flags |= elfcpp::DF_1_NOOPEN;
4528 if (parameters->options().nodump())
4529 flags |= elfcpp::DF_1_NODUMP;
4530 if (!parameters->options().shared())
4531 flags &= ~(elfcpp::DF_1_INITFIRST
4532 | elfcpp::DF_1_NODELETE
4533 | elfcpp::DF_1_NOOPEN);
4534 if (parameters->options().origin())
4535 flags |= elfcpp::DF_1_ORIGIN;
4536 if (parameters->options().now())
4537 flags |= elfcpp::DF_1_NOW;
4538 if (parameters->options().Bgroup())
4539 flags |= elfcpp::DF_1_GROUP;
4541 odyn->add_constant(elfcpp::DT_FLAGS_1, flags);
4544 // Set the size of the _DYNAMIC symbol table to be the size of the
4548 Layout::set_dynamic_symbol_size(const Symbol_table* symtab)
4550 Output_data_dynamic* const odyn = this->dynamic_data_;
4553 odyn->finalize_data_size();
4554 if (this->dynamic_symbol_ == NULL)
4556 off_t data_size = odyn->data_size();
4557 const int size = parameters->target().get_size();
4559 symtab->get_sized_symbol<32>(this->dynamic_symbol_)->set_symsize(data_size);
4560 else if (size == 64)
4561 symtab->get_sized_symbol<64>(this->dynamic_symbol_)->set_symsize(data_size);
4566 // The mapping of input section name prefixes to output section names.
4567 // In some cases one prefix is itself a prefix of another prefix; in
4568 // such a case the longer prefix must come first. These prefixes are
4569 // based on the GNU linker default ELF linker script.
4571 #define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 }
4572 const Layout::Section_name_mapping Layout::section_name_mapping[] =
4574 MAPPING_INIT(".text.", ".text"),
4575 MAPPING_INIT(".rodata.", ".rodata"),
4576 MAPPING_INIT(".data.rel.ro.local", ".data.rel.ro.local"),
4577 MAPPING_INIT(".data.rel.ro", ".data.rel.ro"),
4578 MAPPING_INIT(".data.", ".data"),
4579 MAPPING_INIT(".bss.", ".bss"),
4580 MAPPING_INIT(".tdata.", ".tdata"),
4581 MAPPING_INIT(".tbss.", ".tbss"),
4582 MAPPING_INIT(".init_array.", ".init_array"),
4583 MAPPING_INIT(".fini_array.", ".fini_array"),
4584 MAPPING_INIT(".sdata.", ".sdata"),
4585 MAPPING_INIT(".sbss.", ".sbss"),
4586 // FIXME: In the GNU linker, .sbss2 and .sdata2 are handled
4587 // differently depending on whether it is creating a shared library.
4588 MAPPING_INIT(".sdata2.", ".sdata"),
4589 MAPPING_INIT(".sbss2.", ".sbss"),
4590 MAPPING_INIT(".lrodata.", ".lrodata"),
4591 MAPPING_INIT(".ldata.", ".ldata"),
4592 MAPPING_INIT(".lbss.", ".lbss"),
4593 MAPPING_INIT(".gcc_except_table.", ".gcc_except_table"),
4594 MAPPING_INIT(".gnu.linkonce.d.rel.ro.local.", ".data.rel.ro.local"),
4595 MAPPING_INIT(".gnu.linkonce.d.rel.ro.", ".data.rel.ro"),
4596 MAPPING_INIT(".gnu.linkonce.t.", ".text"),
4597 MAPPING_INIT(".gnu.linkonce.r.", ".rodata"),
4598 MAPPING_INIT(".gnu.linkonce.d.", ".data"),
4599 MAPPING_INIT(".gnu.linkonce.b.", ".bss"),
4600 MAPPING_INIT(".gnu.linkonce.s.", ".sdata"),
4601 MAPPING_INIT(".gnu.linkonce.sb.", ".sbss"),
4602 MAPPING_INIT(".gnu.linkonce.s2.", ".sdata"),
4603 MAPPING_INIT(".gnu.linkonce.sb2.", ".sbss"),
4604 MAPPING_INIT(".gnu.linkonce.wi.", ".debug_info"),
4605 MAPPING_INIT(".gnu.linkonce.td.", ".tdata"),
4606 MAPPING_INIT(".gnu.linkonce.tb.", ".tbss"),
4607 MAPPING_INIT(".gnu.linkonce.lr.", ".lrodata"),
4608 MAPPING_INIT(".gnu.linkonce.l.", ".ldata"),
4609 MAPPING_INIT(".gnu.linkonce.lb.", ".lbss"),
4610 MAPPING_INIT(".ARM.extab", ".ARM.extab"),
4611 MAPPING_INIT(".gnu.linkonce.armextab.", ".ARM.extab"),
4612 MAPPING_INIT(".ARM.exidx", ".ARM.exidx"),
4613 MAPPING_INIT(".gnu.linkonce.armexidx.", ".ARM.exidx"),
4617 const int Layout::section_name_mapping_count =
4618 (sizeof(Layout::section_name_mapping)
4619 / sizeof(Layout::section_name_mapping[0]));
4621 // Choose the output section name to use given an input section name.
4622 // Set *PLEN to the length of the name. *PLEN is initialized to the
4626 Layout::output_section_name(const Relobj* relobj, const char* name,
4629 // gcc 4.3 generates the following sorts of section names when it
4630 // needs a section name specific to a function:
4636 // .data.rel.local.FN
4638 // .data.rel.ro.local.FN
4645 // The GNU linker maps all of those to the part before the .FN,
4646 // except that .data.rel.local.FN is mapped to .data, and
4647 // .data.rel.ro.local.FN is mapped to .data.rel.ro. The sections
4648 // beginning with .data.rel.ro.local are grouped together.
4650 // For an anonymous namespace, the string FN can contain a '.'.
4652 // Also of interest: .rodata.strN.N, .rodata.cstN, both of which the
4653 // GNU linker maps to .rodata.
4655 // The .data.rel.ro sections are used with -z relro. The sections
4656 // are recognized by name. We use the same names that the GNU
4657 // linker does for these sections.
4659 // It is hard to handle this in a principled way, so we don't even
4660 // try. We use a table of mappings. If the input section name is
4661 // not found in the table, we simply use it as the output section
4664 const Section_name_mapping* psnm = section_name_mapping;
4665 for (int i = 0; i < section_name_mapping_count; ++i, ++psnm)
4667 if (strncmp(name, psnm->from, psnm->fromlen) == 0)
4669 *plen = psnm->tolen;
4674 // As an additional complication, .ctors sections are output in
4675 // either .ctors or .init_array sections, and .dtors sections are
4676 // output in either .dtors or .fini_array sections.
4677 if (is_prefix_of(".ctors.", name) || is_prefix_of(".dtors.", name))
4679 if (parameters->options().ctors_in_init_array())
4682 return name[1] == 'c' ? ".init_array" : ".fini_array";
4687 return name[1] == 'c' ? ".ctors" : ".dtors";
4690 if (parameters->options().ctors_in_init_array()
4691 && (strcmp(name, ".ctors") == 0 || strcmp(name, ".dtors") == 0))
4693 // To make .init_array/.fini_array work with gcc we must exclude
4694 // .ctors and .dtors sections from the crtbegin and crtend
4697 || (!Layout::match_file_name(relobj, "crtbegin")
4698 && !Layout::match_file_name(relobj, "crtend")))
4701 return name[1] == 'c' ? ".init_array" : ".fini_array";
4708 // Return true if RELOBJ is an input file whose base name matches
4709 // FILE_NAME. The base name must have an extension of ".o", and must
4710 // be exactly FILE_NAME.o or FILE_NAME, one character, ".o". This is
4711 // to match crtbegin.o as well as crtbeginS.o without getting confused
4712 // by other possibilities. Overall matching the file name this way is
4713 // a dreadful hack, but the GNU linker does it in order to better
4714 // support gcc, and we need to be compatible.
4717 Layout::match_file_name(const Relobj* relobj, const char* match)
4719 const std::string& file_name(relobj->name());
4720 const char* base_name = lbasename(file_name.c_str());
4721 size_t match_len = strlen(match);
4722 if (strncmp(base_name, match, match_len) != 0)
4724 size_t base_len = strlen(base_name);
4725 if (base_len != match_len + 2 && base_len != match_len + 3)
4727 return memcmp(base_name + base_len - 2, ".o", 2) == 0;
4730 // Check if a comdat group or .gnu.linkonce section with the given
4731 // NAME is selected for the link. If there is already a section,
4732 // *KEPT_SECTION is set to point to the existing section and the
4733 // function returns false. Otherwise, OBJECT, SHNDX, IS_COMDAT, and
4734 // IS_GROUP_NAME are recorded for this NAME in the layout object,
4735 // *KEPT_SECTION is set to the internal copy and the function returns
4739 Layout::find_or_add_kept_section(const std::string& name,
4744 Kept_section** kept_section)
4746 // It's normal to see a couple of entries here, for the x86 thunk
4747 // sections. If we see more than a few, we're linking a C++
4748 // program, and we resize to get more space to minimize rehashing.
4749 if (this->signatures_.size() > 4
4750 && !this->resized_signatures_)
4752 reserve_unordered_map(&this->signatures_,
4753 this->number_of_input_files_ * 64);
4754 this->resized_signatures_ = true;
4757 Kept_section candidate;
4758 std::pair<Signatures::iterator, bool> ins =
4759 this->signatures_.insert(std::make_pair(name, candidate));
4761 if (kept_section != NULL)
4762 *kept_section = &ins.first->second;
4765 // This is the first time we've seen this signature.
4766 ins.first->second.set_object(object);
4767 ins.first->second.set_shndx(shndx);
4769 ins.first->second.set_is_comdat();
4771 ins.first->second.set_is_group_name();
4775 // We have already seen this signature.
4777 if (ins.first->second.is_group_name())
4779 // We've already seen a real section group with this signature.
4780 // If the kept group is from a plugin object, and we're in the
4781 // replacement phase, accept the new one as a replacement.
4782 if (ins.first->second.object() == NULL
4783 && parameters->options().plugins()->in_replacement_phase())
4785 ins.first->second.set_object(object);
4786 ins.first->second.set_shndx(shndx);
4791 else if (is_group_name)
4793 // This is a real section group, and we've already seen a
4794 // linkonce section with this signature. Record that we've seen
4795 // a section group, and don't include this section group.
4796 ins.first->second.set_is_group_name();
4801 // We've already seen a linkonce section and this is a linkonce
4802 // section. These don't block each other--this may be the same
4803 // symbol name with different section types.
4808 // Store the allocated sections into the section list.
4811 Layout::get_allocated_sections(Section_list* section_list) const
4813 for (Section_list::const_iterator p = this->section_list_.begin();
4814 p != this->section_list_.end();
4816 if (((*p)->flags() & elfcpp::SHF_ALLOC) != 0)
4817 section_list->push_back(*p);
4820 // Create an output segment.
4823 Layout::make_output_segment(elfcpp::Elf_Word type, elfcpp::Elf_Word flags)
4825 gold_assert(!parameters->options().relocatable());
4826 Output_segment* oseg = new Output_segment(type, flags);
4827 this->segment_list_.push_back(oseg);
4829 if (type == elfcpp::PT_TLS)
4830 this->tls_segment_ = oseg;
4831 else if (type == elfcpp::PT_GNU_RELRO)
4832 this->relro_segment_ = oseg;
4833 else if (type == elfcpp::PT_INTERP)
4834 this->interp_segment_ = oseg;
4839 // Return the file offset of the normal symbol table.
4842 Layout::symtab_section_offset() const
4844 if (this->symtab_section_ != NULL)
4845 return this->symtab_section_->offset();
4849 // Return the section index of the normal symbol table. It may have
4850 // been stripped by the -s/--strip-all option.
4853 Layout::symtab_section_shndx() const
4855 if (this->symtab_section_ != NULL)
4856 return this->symtab_section_->out_shndx();
4860 // Write out the Output_sections. Most won't have anything to write,
4861 // since most of the data will come from input sections which are
4862 // handled elsewhere. But some Output_sections do have Output_data.
4865 Layout::write_output_sections(Output_file* of) const
4867 for (Section_list::const_iterator p = this->section_list_.begin();
4868 p != this->section_list_.end();
4871 if (!(*p)->after_input_sections())
4876 // Write out data not associated with a section or the symbol table.
4879 Layout::write_data(const Symbol_table* symtab, Output_file* of) const
4881 if (!parameters->options().strip_all())
4883 const Output_section* symtab_section = this->symtab_section_;
4884 for (Section_list::const_iterator p = this->section_list_.begin();
4885 p != this->section_list_.end();
4888 if ((*p)->needs_symtab_index())
4890 gold_assert(symtab_section != NULL);
4891 unsigned int index = (*p)->symtab_index();
4892 gold_assert(index > 0 && index != -1U);
4893 off_t off = (symtab_section->offset()
4894 + index * symtab_section->entsize());
4895 symtab->write_section_symbol(*p, this->symtab_xindex_, of, off);
4900 const Output_section* dynsym_section = this->dynsym_section_;
4901 for (Section_list::const_iterator p = this->section_list_.begin();
4902 p != this->section_list_.end();
4905 if ((*p)->needs_dynsym_index())
4907 gold_assert(dynsym_section != NULL);
4908 unsigned int index = (*p)->dynsym_index();
4909 gold_assert(index > 0 && index != -1U);
4910 off_t off = (dynsym_section->offset()
4911 + index * dynsym_section->entsize());
4912 symtab->write_section_symbol(*p, this->dynsym_xindex_, of, off);
4916 // Write out the Output_data which are not in an Output_section.
4917 for (Data_list::const_iterator p = this->special_output_list_.begin();
4918 p != this->special_output_list_.end();
4923 // Write out the Output_sections which can only be written after the
4924 // input sections are complete.
4927 Layout::write_sections_after_input_sections(Output_file* of)
4929 // Determine the final section offsets, and thus the final output
4930 // file size. Note we finalize the .shstrab last, to allow the
4931 // after_input_section sections to modify their section-names before
4933 if (this->any_postprocessing_sections_)
4935 off_t off = this->output_file_size_;
4936 off = this->set_section_offsets(off, POSTPROCESSING_SECTIONS_PASS);
4938 // Now that we've finalized the names, we can finalize the shstrab.
4940 this->set_section_offsets(off,
4941 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS);
4943 if (off > this->output_file_size_)
4946 this->output_file_size_ = off;
4950 for (Section_list::const_iterator p = this->section_list_.begin();
4951 p != this->section_list_.end();
4954 if ((*p)->after_input_sections())
4958 this->section_headers_->write(of);
4961 // If the build ID requires computing a checksum, do so here, and
4962 // write it out. We compute a checksum over the entire file because
4963 // that is simplest.
4966 Layout::write_build_id(Output_file* of) const
4968 if (this->build_id_note_ == NULL)
4971 const unsigned char* iv = of->get_input_view(0, this->output_file_size_);
4973 unsigned char* ov = of->get_output_view(this->build_id_note_->offset(),
4974 this->build_id_note_->data_size());
4976 const char* style = parameters->options().build_id();
4977 if (strcmp(style, "sha1") == 0)
4980 sha1_init_ctx(&ctx);
4981 sha1_process_bytes(iv, this->output_file_size_, &ctx);
4982 sha1_finish_ctx(&ctx, ov);
4984 else if (strcmp(style, "md5") == 0)
4988 md5_process_bytes(iv, this->output_file_size_, &ctx);
4989 md5_finish_ctx(&ctx, ov);
4994 of->write_output_view(this->build_id_note_->offset(),
4995 this->build_id_note_->data_size(),
4998 of->free_input_view(0, this->output_file_size_, iv);
5001 // Write out a binary file. This is called after the link is
5002 // complete. IN is the temporary output file we used to generate the
5003 // ELF code. We simply walk through the segments, read them from
5004 // their file offset in IN, and write them to their load address in
5005 // the output file. FIXME: with a bit more work, we could support
5006 // S-records and/or Intel hex format here.
5009 Layout::write_binary(Output_file* in) const
5011 gold_assert(parameters->options().oformat_enum()
5012 == General_options::OBJECT_FORMAT_BINARY);
5014 // Get the size of the binary file.
5015 uint64_t max_load_address = 0;
5016 for (Segment_list::const_iterator p = this->segment_list_.begin();
5017 p != this->segment_list_.end();
5020 if ((*p)->type() == elfcpp::PT_LOAD && (*p)->filesz() > 0)
5022 uint64_t max_paddr = (*p)->paddr() + (*p)->filesz();
5023 if (max_paddr > max_load_address)
5024 max_load_address = max_paddr;
5028 Output_file out(parameters->options().output_file_name());
5029 out.open(max_load_address);
5031 for (Segment_list::const_iterator p = this->segment_list_.begin();
5032 p != this->segment_list_.end();
5035 if ((*p)->type() == elfcpp::PT_LOAD && (*p)->filesz() > 0)
5037 const unsigned char* vin = in->get_input_view((*p)->offset(),
5039 unsigned char* vout = out.get_output_view((*p)->paddr(),
5041 memcpy(vout, vin, (*p)->filesz());
5042 out.write_output_view((*p)->paddr(), (*p)->filesz(), vout);
5043 in->free_input_view((*p)->offset(), (*p)->filesz(), vin);
5050 // Print the output sections to the map file.
5053 Layout::print_to_mapfile(Mapfile* mapfile) const
5055 for (Segment_list::const_iterator p = this->segment_list_.begin();
5056 p != this->segment_list_.end();
5058 (*p)->print_sections_to_mapfile(mapfile);
5061 // Print statistical information to stderr. This is used for --stats.
5064 Layout::print_stats() const
5066 this->namepool_.print_stats("section name pool");
5067 this->sympool_.print_stats("output symbol name pool");
5068 this->dynpool_.print_stats("dynamic name pool");
5070 for (Section_list::const_iterator p = this->section_list_.begin();
5071 p != this->section_list_.end();
5073 (*p)->print_merge_stats();
5076 // Write_sections_task methods.
5078 // We can always run this task.
5081 Write_sections_task::is_runnable()
5086 // We need to unlock both OUTPUT_SECTIONS_BLOCKER and FINAL_BLOCKER
5090 Write_sections_task::locks(Task_locker* tl)
5092 tl->add(this, this->output_sections_blocker_);
5093 tl->add(this, this->final_blocker_);
5096 // Run the task--write out the data.
5099 Write_sections_task::run(Workqueue*)
5101 this->layout_->write_output_sections(this->of_);
5104 // Write_data_task methods.
5106 // We can always run this task.
5109 Write_data_task::is_runnable()
5114 // We need to unlock FINAL_BLOCKER when finished.
5117 Write_data_task::locks(Task_locker* tl)
5119 tl->add(this, this->final_blocker_);
5122 // Run the task--write out the data.
5125 Write_data_task::run(Workqueue*)
5127 this->layout_->write_data(this->symtab_, this->of_);
5130 // Write_symbols_task methods.
5132 // We can always run this task.
5135 Write_symbols_task::is_runnable()
5140 // We need to unlock FINAL_BLOCKER when finished.
5143 Write_symbols_task::locks(Task_locker* tl)
5145 tl->add(this, this->final_blocker_);
5148 // Run the task--write out the symbols.
5151 Write_symbols_task::run(Workqueue*)
5153 this->symtab_->write_globals(this->sympool_, this->dynpool_,
5154 this->layout_->symtab_xindex(),
5155 this->layout_->dynsym_xindex(), this->of_);
5158 // Write_after_input_sections_task methods.
5160 // We can only run this task after the input sections have completed.
5163 Write_after_input_sections_task::is_runnable()
5165 if (this->input_sections_blocker_->is_blocked())
5166 return this->input_sections_blocker_;
5170 // We need to unlock FINAL_BLOCKER when finished.
5173 Write_after_input_sections_task::locks(Task_locker* tl)
5175 tl->add(this, this->final_blocker_);
5181 Write_after_input_sections_task::run(Workqueue*)
5183 this->layout_->write_sections_after_input_sections(this->of_);
5186 // Close_task_runner methods.
5188 // Run the task--close the file.
5191 Close_task_runner::run(Workqueue*, const Task*)
5193 // If we need to compute a checksum for the BUILD if, we do so here.
5194 this->layout_->write_build_id(this->of_);
5196 // If we've been asked to create a binary file, we do so here.
5197 if (this->options_->oformat_enum() != General_options::OBJECT_FORMAT_ELF)
5198 this->layout_->write_binary(this->of_);
5203 // Instantiate the templates we need. We could use the configure
5204 // script to restrict this to only the ones for implemented targets.
5206 #ifdef HAVE_TARGET_32_LITTLE
5209 Layout::init_fixed_output_section<32, false>(
5211 elfcpp::Shdr<32, false>& shdr);
5214 #ifdef HAVE_TARGET_32_BIG
5217 Layout::init_fixed_output_section<32, true>(
5219 elfcpp::Shdr<32, true>& shdr);
5222 #ifdef HAVE_TARGET_64_LITTLE
5225 Layout::init_fixed_output_section<64, false>(
5227 elfcpp::Shdr<64, false>& shdr);
5230 #ifdef HAVE_TARGET_64_BIG
5233 Layout::init_fixed_output_section<64, true>(
5235 elfcpp::Shdr<64, true>& shdr);
5238 #ifdef HAVE_TARGET_32_LITTLE
5241 Layout::layout<32, false>(Sized_relobj_file<32, false>* object,
5244 const elfcpp::Shdr<32, false>& shdr,
5245 unsigned int, unsigned int, off_t*);
5248 #ifdef HAVE_TARGET_32_BIG
5251 Layout::layout<32, true>(Sized_relobj_file<32, true>* object,
5254 const elfcpp::Shdr<32, true>& shdr,
5255 unsigned int, unsigned int, off_t*);
5258 #ifdef HAVE_TARGET_64_LITTLE
5261 Layout::layout<64, false>(Sized_relobj_file<64, false>* object,
5264 const elfcpp::Shdr<64, false>& shdr,
5265 unsigned int, unsigned int, off_t*);
5268 #ifdef HAVE_TARGET_64_BIG
5271 Layout::layout<64, true>(Sized_relobj_file<64, true>* object,
5274 const elfcpp::Shdr<64, true>& shdr,
5275 unsigned int, unsigned int, off_t*);
5278 #ifdef HAVE_TARGET_32_LITTLE
5281 Layout::layout_reloc<32, false>(Sized_relobj_file<32, false>* object,
5282 unsigned int reloc_shndx,
5283 const elfcpp::Shdr<32, false>& shdr,
5284 Output_section* data_section,
5285 Relocatable_relocs* rr);
5288 #ifdef HAVE_TARGET_32_BIG
5291 Layout::layout_reloc<32, true>(Sized_relobj_file<32, true>* object,
5292 unsigned int reloc_shndx,
5293 const elfcpp::Shdr<32, true>& shdr,
5294 Output_section* data_section,
5295 Relocatable_relocs* rr);
5298 #ifdef HAVE_TARGET_64_LITTLE
5301 Layout::layout_reloc<64, false>(Sized_relobj_file<64, false>* object,
5302 unsigned int reloc_shndx,
5303 const elfcpp::Shdr<64, false>& shdr,
5304 Output_section* data_section,
5305 Relocatable_relocs* rr);
5308 #ifdef HAVE_TARGET_64_BIG
5311 Layout::layout_reloc<64, true>(Sized_relobj_file<64, true>* object,
5312 unsigned int reloc_shndx,
5313 const elfcpp::Shdr<64, true>& shdr,
5314 Output_section* data_section,
5315 Relocatable_relocs* rr);
5318 #ifdef HAVE_TARGET_32_LITTLE
5321 Layout::layout_group<32, false>(Symbol_table* symtab,
5322 Sized_relobj_file<32, false>* object,
5324 const char* group_section_name,
5325 const char* signature,
5326 const elfcpp::Shdr<32, false>& shdr,
5327 elfcpp::Elf_Word flags,
5328 std::vector<unsigned int>* shndxes);
5331 #ifdef HAVE_TARGET_32_BIG
5334 Layout::layout_group<32, true>(Symbol_table* symtab,
5335 Sized_relobj_file<32, true>* object,
5337 const char* group_section_name,
5338 const char* signature,
5339 const elfcpp::Shdr<32, true>& shdr,
5340 elfcpp::Elf_Word flags,
5341 std::vector<unsigned int>* shndxes);
5344 #ifdef HAVE_TARGET_64_LITTLE
5347 Layout::layout_group<64, false>(Symbol_table* symtab,
5348 Sized_relobj_file<64, false>* object,
5350 const char* group_section_name,
5351 const char* signature,
5352 const elfcpp::Shdr<64, false>& shdr,
5353 elfcpp::Elf_Word flags,
5354 std::vector<unsigned int>* shndxes);
5357 #ifdef HAVE_TARGET_64_BIG
5360 Layout::layout_group<64, true>(Symbol_table* symtab,
5361 Sized_relobj_file<64, true>* object,
5363 const char* group_section_name,
5364 const char* signature,
5365 const elfcpp::Shdr<64, true>& shdr,
5366 elfcpp::Elf_Word flags,
5367 std::vector<unsigned int>* shndxes);
5370 #ifdef HAVE_TARGET_32_LITTLE
5373 Layout::layout_eh_frame<32, false>(Sized_relobj_file<32, false>* object,
5374 const unsigned char* symbols,
5376 const unsigned char* symbol_names,
5377 off_t symbol_names_size,
5379 const elfcpp::Shdr<32, false>& shdr,
5380 unsigned int reloc_shndx,
5381 unsigned int reloc_type,
5385 #ifdef HAVE_TARGET_32_BIG
5388 Layout::layout_eh_frame<32, true>(Sized_relobj_file<32, true>* object,
5389 const unsigned char* symbols,
5391 const unsigned char* symbol_names,
5392 off_t symbol_names_size,
5394 const elfcpp::Shdr<32, true>& shdr,
5395 unsigned int reloc_shndx,
5396 unsigned int reloc_type,
5400 #ifdef HAVE_TARGET_64_LITTLE
5403 Layout::layout_eh_frame<64, false>(Sized_relobj_file<64, false>* object,
5404 const unsigned char* symbols,
5406 const unsigned char* symbol_names,
5407 off_t symbol_names_size,
5409 const elfcpp::Shdr<64, false>& shdr,
5410 unsigned int reloc_shndx,
5411 unsigned int reloc_type,
5415 #ifdef HAVE_TARGET_64_BIG
5418 Layout::layout_eh_frame<64, true>(Sized_relobj_file<64, true>* object,
5419 const unsigned char* symbols,
5421 const unsigned char* symbol_names,
5422 off_t symbol_names_size,
5424 const elfcpp::Shdr<64, true>& shdr,
5425 unsigned int reloc_shndx,
5426 unsigned int reloc_type,
5430 #ifdef HAVE_TARGET_32_LITTLE
5433 Layout::add_to_gdb_index(bool is_type_unit,
5434 Sized_relobj<32, false>* object,
5435 const unsigned char* symbols,
5438 unsigned int reloc_shndx,
5439 unsigned int reloc_type);
5442 #ifdef HAVE_TARGET_32_BIG
5445 Layout::add_to_gdb_index(bool is_type_unit,
5446 Sized_relobj<32, true>* object,
5447 const unsigned char* symbols,
5450 unsigned int reloc_shndx,
5451 unsigned int reloc_type);
5454 #ifdef HAVE_TARGET_64_LITTLE
5457 Layout::add_to_gdb_index(bool is_type_unit,
5458 Sized_relobj<64, false>* object,
5459 const unsigned char* symbols,
5462 unsigned int reloc_shndx,
5463 unsigned int reloc_type);
5466 #ifdef HAVE_TARGET_64_BIG
5469 Layout::add_to_gdb_index(bool is_type_unit,
5470 Sized_relobj<64, true>* object,
5471 const unsigned char* symbols,
5474 unsigned int reloc_shndx,
5475 unsigned int reloc_type);
5478 } // End namespace gold.