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 // These are the debug sections that are actually used by gdb.
457 // Currently, we've checked versions of gdb up to and including 7.4.
458 // We only check the part of the name that follows ".debug_" or
461 static const char* gdb_sections[] =
464 "addr", // Fission extension
465 // "aranges", // not used by gdb as of 7.4
473 // "pubnames", // not used by gdb as of 7.4
474 // "pubtypes", // not used by gdb as of 7.4
479 // This is the minimum set of sections needed for line numbers.
481 static const char* lines_only_debug_sections[] =
484 // "addr", // Fission extension
485 // "aranges", // not used by gdb as of 7.4
493 // "pubnames", // not used by gdb as of 7.4
494 // "pubtypes", // not used by gdb as of 7.4
499 // These sections are the DWARF fast-lookup tables, and are not needed
500 // when building a .gdb_index section.
502 static const char* gdb_fast_lookup_sections[] =
509 // Returns whether the given debug section is in the list of
510 // debug-sections-used-by-some-version-of-gdb. SUFFIX is the
511 // portion of the name following ".debug_" or ".zdebug_".
514 is_gdb_debug_section(const char* suffix)
516 // We can do this faster: binary search or a hashtable. But why bother?
517 for (size_t i = 0; i < sizeof(gdb_sections)/sizeof(*gdb_sections); ++i)
518 if (strcmp(suffix, gdb_sections[i]) == 0)
523 // Returns whether the given section is needed for lines-only debugging.
526 is_lines_only_debug_section(const char* suffix)
528 // We can do this faster: binary search or a hashtable. But why bother?
530 i < sizeof(lines_only_debug_sections)/sizeof(*lines_only_debug_sections);
532 if (strcmp(suffix, lines_only_debug_sections[i]) == 0)
537 // Returns whether the given section is a fast-lookup section that
538 // will not be needed when building a .gdb_index section.
541 is_gdb_fast_lookup_section(const char* suffix)
543 // We can do this faster: binary search or a hashtable. But why bother?
545 i < sizeof(gdb_fast_lookup_sections)/sizeof(*gdb_fast_lookup_sections);
547 if (strcmp(suffix, gdb_fast_lookup_sections[i]) == 0)
552 // Sometimes we compress sections. This is typically done for
553 // sections that are not part of normal program execution (such as
554 // .debug_* sections), and where the readers of these sections know
555 // how to deal with compressed sections. This routine doesn't say for
556 // certain whether we'll compress -- it depends on commandline options
557 // as well -- just whether this section is a candidate for compression.
558 // (The Output_compressed_section class decides whether to compress
559 // a given section, and picks the name of the compressed section.)
562 is_compressible_debug_section(const char* secname)
564 return (is_prefix_of(".debug", secname));
567 // We may see compressed debug sections in input files. Return TRUE
568 // if this is the name of a compressed debug section.
571 is_compressed_debug_section(const char* secname)
573 return (is_prefix_of(".zdebug", secname));
576 // Whether to include this section in the link.
578 template<int size, bool big_endian>
580 Layout::include_section(Sized_relobj_file<size, big_endian>*, const char* name,
581 const elfcpp::Shdr<size, big_endian>& shdr)
583 if (shdr.get_sh_flags() & elfcpp::SHF_EXCLUDE)
586 switch (shdr.get_sh_type())
588 case elfcpp::SHT_NULL:
589 case elfcpp::SHT_SYMTAB:
590 case elfcpp::SHT_DYNSYM:
591 case elfcpp::SHT_HASH:
592 case elfcpp::SHT_DYNAMIC:
593 case elfcpp::SHT_SYMTAB_SHNDX:
596 case elfcpp::SHT_STRTAB:
597 // Discard the sections which have special meanings in the ELF
598 // ABI. Keep others (e.g., .stabstr). We could also do this by
599 // checking the sh_link fields of the appropriate sections.
600 return (strcmp(name, ".dynstr") != 0
601 && strcmp(name, ".strtab") != 0
602 && strcmp(name, ".shstrtab") != 0);
604 case elfcpp::SHT_RELA:
605 case elfcpp::SHT_REL:
606 case elfcpp::SHT_GROUP:
607 // If we are emitting relocations these should be handled
609 gold_assert(!parameters->options().relocatable()
610 && !parameters->options().emit_relocs());
613 case elfcpp::SHT_PROGBITS:
614 if (parameters->options().strip_debug()
615 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
617 if (is_debug_info_section(name))
620 if (parameters->options().strip_debug_non_line()
621 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
623 // Debugging sections can only be recognized by name.
624 if (is_prefix_of(".debug_", name)
625 && !is_lines_only_debug_section(name + 7))
627 if (is_prefix_of(".zdebug_", name)
628 && !is_lines_only_debug_section(name + 8))
631 if (parameters->options().strip_debug_gdb()
632 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
634 // Debugging sections can only be recognized by name.
635 if (is_prefix_of(".debug_", name)
636 && !is_gdb_debug_section(name + 7))
638 if (is_prefix_of(".zdebug_", name)
639 && !is_gdb_debug_section(name + 8))
642 if (parameters->options().gdb_index()
643 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
645 // When building .gdb_index, we can strip .debug_pubnames,
646 // .debug_pubtypes, and .debug_aranges sections.
647 if (is_prefix_of(".debug_", name)
648 && is_gdb_fast_lookup_section(name + 7))
650 if (is_prefix_of(".zdebug_", name)
651 && is_gdb_fast_lookup_section(name + 8))
654 if (parameters->options().strip_lto_sections()
655 && !parameters->options().relocatable()
656 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
658 // Ignore LTO sections containing intermediate code.
659 if (is_prefix_of(".gnu.lto_", name))
662 // The GNU linker strips .gnu_debuglink sections, so we do too.
663 // This is a feature used to keep debugging information in
665 if (strcmp(name, ".gnu_debuglink") == 0)
674 // Return an output section named NAME, or NULL if there is none.
677 Layout::find_output_section(const char* name) const
679 for (Section_list::const_iterator p = this->section_list_.begin();
680 p != this->section_list_.end();
682 if (strcmp((*p)->name(), name) == 0)
687 // Return an output segment of type TYPE, with segment flags SET set
688 // and segment flags CLEAR clear. Return NULL if there is none.
691 Layout::find_output_segment(elfcpp::PT type, elfcpp::Elf_Word set,
692 elfcpp::Elf_Word clear) const
694 for (Segment_list::const_iterator p = this->segment_list_.begin();
695 p != this->segment_list_.end();
697 if (static_cast<elfcpp::PT>((*p)->type()) == type
698 && ((*p)->flags() & set) == set
699 && ((*p)->flags() & clear) == 0)
704 // When we put a .ctors or .dtors section with more than one word into
705 // a .init_array or .fini_array section, we need to reverse the words
706 // in the .ctors/.dtors section. This is because .init_array executes
707 // constructors front to back, where .ctors executes them back to
708 // front, and vice-versa for .fini_array/.dtors. Although we do want
709 // to remap .ctors/.dtors into .init_array/.fini_array because it can
710 // be more efficient, we don't want to change the order in which
711 // constructors/destructors are run. This set just keeps track of
712 // these sections which need to be reversed. It is only changed by
713 // Layout::layout. It should be a private member of Layout, but that
714 // would require layout.h to #include object.h to get the definition
716 static Unordered_set<Section_id, Section_id_hash> ctors_sections_in_init_array;
718 // Return whether OBJECT/SHNDX is a .ctors/.dtors section mapped to a
719 // .init_array/.fini_array section.
722 Layout::is_ctors_in_init_array(Relobj* relobj, unsigned int shndx) const
724 return (ctors_sections_in_init_array.find(Section_id(relobj, shndx))
725 != ctors_sections_in_init_array.end());
728 // Return the output section to use for section NAME with type TYPE
729 // and section flags FLAGS. NAME must be canonicalized in the string
730 // pool, and NAME_KEY is the key. ORDER is where this should appear
731 // in the output sections. IS_RELRO is true for a relro section.
734 Layout::get_output_section(const char* name, Stringpool::Key name_key,
735 elfcpp::Elf_Word type, elfcpp::Elf_Xword flags,
736 Output_section_order order, bool is_relro)
738 elfcpp::Elf_Word lookup_type = type;
740 // For lookup purposes, treat INIT_ARRAY, FINI_ARRAY, and
741 // PREINIT_ARRAY like PROGBITS. This ensures that we combine
742 // .init_array, .fini_array, and .preinit_array sections by name
743 // whatever their type in the input file. We do this because the
744 // types are not always right in the input files.
745 if (lookup_type == elfcpp::SHT_INIT_ARRAY
746 || lookup_type == elfcpp::SHT_FINI_ARRAY
747 || lookup_type == elfcpp::SHT_PREINIT_ARRAY)
748 lookup_type = elfcpp::SHT_PROGBITS;
750 elfcpp::Elf_Xword lookup_flags = flags;
752 // Ignoring SHF_WRITE and SHF_EXECINSTR here means that we combine
753 // read-write with read-only sections. Some other ELF linkers do
754 // not do this. FIXME: Perhaps there should be an option
756 lookup_flags &= ~(elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR);
758 const Key key(name_key, std::make_pair(lookup_type, lookup_flags));
759 const std::pair<Key, Output_section*> v(key, NULL);
760 std::pair<Section_name_map::iterator, bool> ins(
761 this->section_name_map_.insert(v));
764 return ins.first->second;
767 // This is the first time we've seen this name/type/flags
768 // combination. For compatibility with the GNU linker, we
769 // combine sections with contents and zero flags with sections
770 // with non-zero flags. This is a workaround for cases where
771 // assembler code forgets to set section flags. FIXME: Perhaps
772 // there should be an option to control this.
773 Output_section* os = NULL;
775 if (lookup_type == elfcpp::SHT_PROGBITS)
779 Output_section* same_name = this->find_output_section(name);
780 if (same_name != NULL
781 && (same_name->type() == elfcpp::SHT_PROGBITS
782 || same_name->type() == elfcpp::SHT_INIT_ARRAY
783 || same_name->type() == elfcpp::SHT_FINI_ARRAY
784 || same_name->type() == elfcpp::SHT_PREINIT_ARRAY)
785 && (same_name->flags() & elfcpp::SHF_TLS) == 0)
788 else if ((flags & elfcpp::SHF_TLS) == 0)
790 elfcpp::Elf_Xword zero_flags = 0;
791 const Key zero_key(name_key, std::make_pair(lookup_type,
793 Section_name_map::iterator p =
794 this->section_name_map_.find(zero_key);
795 if (p != this->section_name_map_.end())
801 os = this->make_output_section(name, type, flags, order, is_relro);
803 ins.first->second = os;
808 // Returns TRUE iff NAME (an input section from RELOBJ) will
809 // be mapped to an output section that should be KEPT.
812 Layout::keep_input_section(const Relobj* relobj, const char* name)
814 if (! this->script_options_->saw_sections_clause())
817 Script_sections* ss = this->script_options_->script_sections();
818 const char* file_name = relobj == NULL ? NULL : relobj->name().c_str();
819 Output_section** output_section_slot;
820 Script_sections::Section_type script_section_type;
823 name = ss->output_section_name(file_name, name, &output_section_slot,
824 &script_section_type, &keep);
825 return name != NULL && keep;
828 // Pick the output section to use for section NAME, in input file
829 // RELOBJ, with type TYPE and flags FLAGS. RELOBJ may be NULL for a
830 // linker created section. IS_INPUT_SECTION is true if we are
831 // choosing an output section for an input section found in a input
832 // file. ORDER is where this section should appear in the output
833 // sections. IS_RELRO is true for a relro section. This will return
834 // NULL if the input section should be discarded.
837 Layout::choose_output_section(const Relobj* relobj, const char* name,
838 elfcpp::Elf_Word type, elfcpp::Elf_Xword flags,
839 bool is_input_section, Output_section_order order,
842 // We should not see any input sections after we have attached
843 // sections to segments.
844 gold_assert(!is_input_section || !this->sections_are_attached_);
846 // Some flags in the input section should not be automatically
847 // copied to the output section.
848 flags &= ~ (elfcpp::SHF_INFO_LINK
851 | elfcpp::SHF_STRINGS);
853 // We only clear the SHF_LINK_ORDER flag in for
854 // a non-relocatable link.
855 if (!parameters->options().relocatable())
856 flags &= ~elfcpp::SHF_LINK_ORDER;
858 if (this->script_options_->saw_sections_clause())
860 // We are using a SECTIONS clause, so the output section is
861 // chosen based only on the name.
863 Script_sections* ss = this->script_options_->script_sections();
864 const char* file_name = relobj == NULL ? NULL : relobj->name().c_str();
865 Output_section** output_section_slot;
866 Script_sections::Section_type script_section_type;
867 const char* orig_name = name;
869 name = ss->output_section_name(file_name, name, &output_section_slot,
870 &script_section_type, &keep);
874 gold_debug(DEBUG_SCRIPT, _("Unable to create output section '%s' "
875 "because it is not allowed by the "
876 "SECTIONS clause of the linker script"),
878 // The SECTIONS clause says to discard this input section.
882 // We can only handle script section types ST_NONE and ST_NOLOAD.
883 switch (script_section_type)
885 case Script_sections::ST_NONE:
887 case Script_sections::ST_NOLOAD:
888 flags &= elfcpp::SHF_ALLOC;
894 // If this is an orphan section--one not mentioned in the linker
895 // script--then OUTPUT_SECTION_SLOT will be NULL, and we do the
896 // default processing below.
898 if (output_section_slot != NULL)
900 if (*output_section_slot != NULL)
902 (*output_section_slot)->update_flags_for_input_section(flags);
903 return *output_section_slot;
906 // We don't put sections found in the linker script into
907 // SECTION_NAME_MAP_. That keeps us from getting confused
908 // if an orphan section is mapped to a section with the same
909 // name as one in the linker script.
911 name = this->namepool_.add(name, false, NULL);
913 Output_section* os = this->make_output_section(name, type, flags,
916 os->set_found_in_sections_clause();
918 // Special handling for NOLOAD sections.
919 if (script_section_type == Script_sections::ST_NOLOAD)
923 // The constructor of Output_section sets addresses of non-ALLOC
924 // sections to 0 by default. We don't want that for NOLOAD
925 // sections even if they have no SHF_ALLOC flag.
926 if ((os->flags() & elfcpp::SHF_ALLOC) == 0
927 && os->is_address_valid())
929 gold_assert(os->address() == 0
930 && !os->is_offset_valid()
931 && !os->is_data_size_valid());
932 os->reset_address_and_file_offset();
936 *output_section_slot = os;
941 // FIXME: Handle SHF_OS_NONCONFORMING somewhere.
943 size_t len = strlen(name);
944 char* uncompressed_name = NULL;
946 // Compressed debug sections should be mapped to the corresponding
947 // uncompressed section.
948 if (is_compressed_debug_section(name))
950 uncompressed_name = new char[len];
951 uncompressed_name[0] = '.';
952 gold_assert(name[0] == '.' && name[1] == 'z');
953 strncpy(&uncompressed_name[1], &name[2], len - 2);
954 uncompressed_name[len - 1] = '\0';
956 name = uncompressed_name;
959 // Turn NAME from the name of the input section into the name of the
962 && !this->script_options_->saw_sections_clause()
963 && !parameters->options().relocatable())
965 const char *orig_name = name;
966 name = parameters->target().output_section_name(relobj, name, &len);
968 name = Layout::output_section_name(relobj, orig_name, &len);
971 Stringpool::Key name_key;
972 name = this->namepool_.add_with_length(name, len, true, &name_key);
974 if (uncompressed_name != NULL)
975 delete[] uncompressed_name;
977 // Find or make the output section. The output section is selected
978 // based on the section name, type, and flags.
979 return this->get_output_section(name, name_key, type, flags, order, is_relro);
982 // For incremental links, record the initial fixed layout of a section
983 // from the base file, and return a pointer to the Output_section.
985 template<int size, bool big_endian>
987 Layout::init_fixed_output_section(const char* name,
988 elfcpp::Shdr<size, big_endian>& shdr)
990 unsigned int sh_type = shdr.get_sh_type();
992 // We preserve the layout of PROGBITS, NOBITS, INIT_ARRAY, FINI_ARRAY,
993 // PRE_INIT_ARRAY, and NOTE sections.
994 // All others will be created from scratch and reallocated.
995 if (!can_incremental_update(sh_type))
998 // If we're generating a .gdb_index section, we need to regenerate
1000 if (parameters->options().gdb_index()
1001 && sh_type == elfcpp::SHT_PROGBITS
1002 && strcmp(name, ".gdb_index") == 0)
1005 typename elfcpp::Elf_types<size>::Elf_Addr sh_addr = shdr.get_sh_addr();
1006 typename elfcpp::Elf_types<size>::Elf_Off sh_offset = shdr.get_sh_offset();
1007 typename elfcpp::Elf_types<size>::Elf_WXword sh_size = shdr.get_sh_size();
1008 typename elfcpp::Elf_types<size>::Elf_WXword sh_flags = shdr.get_sh_flags();
1009 typename elfcpp::Elf_types<size>::Elf_WXword sh_addralign =
1010 shdr.get_sh_addralign();
1012 // Make the output section.
1013 Stringpool::Key name_key;
1014 name = this->namepool_.add(name, true, &name_key);
1015 Output_section* os = this->get_output_section(name, name_key, sh_type,
1016 sh_flags, ORDER_INVALID, false);
1017 os->set_fixed_layout(sh_addr, sh_offset, sh_size, sh_addralign);
1018 if (sh_type != elfcpp::SHT_NOBITS)
1019 this->free_list_.remove(sh_offset, sh_offset + sh_size);
1023 // Return the output section to use for input section SHNDX, with name
1024 // NAME, with header HEADER, from object OBJECT. RELOC_SHNDX is the
1025 // index of a relocation section which applies to this section, or 0
1026 // if none, or -1U if more than one. RELOC_TYPE is the type of the
1027 // relocation section if there is one. Set *OFF to the offset of this
1028 // input section without the output section. Return NULL if the
1029 // section should be discarded. Set *OFF to -1 if the section
1030 // contents should not be written directly to the output file, but
1031 // will instead receive special handling.
1033 template<int size, bool big_endian>
1035 Layout::layout(Sized_relobj_file<size, big_endian>* object, unsigned int shndx,
1036 const char* name, const elfcpp::Shdr<size, big_endian>& shdr,
1037 unsigned int reloc_shndx, unsigned int, off_t* off)
1041 if (!this->include_section(object, name, shdr))
1044 elfcpp::Elf_Word sh_type = shdr.get_sh_type();
1046 // In a relocatable link a grouped section must not be combined with
1047 // any other sections.
1049 if (parameters->options().relocatable()
1050 && (shdr.get_sh_flags() & elfcpp::SHF_GROUP) != 0)
1052 name = this->namepool_.add(name, true, NULL);
1053 os = this->make_output_section(name, sh_type, shdr.get_sh_flags(),
1054 ORDER_INVALID, false);
1058 os = this->choose_output_section(object, name, sh_type,
1059 shdr.get_sh_flags(), true,
1060 ORDER_INVALID, false);
1065 // By default the GNU linker sorts input sections whose names match
1066 // .ctors.*, .dtors.*, .init_array.*, or .fini_array.*. The
1067 // sections are sorted by name. This is used to implement
1068 // constructor priority ordering. We are compatible. When we put
1069 // .ctor sections in .init_array and .dtor sections in .fini_array,
1070 // we must also sort plain .ctor and .dtor sections.
1071 if (!this->script_options_->saw_sections_clause()
1072 && !parameters->options().relocatable()
1073 && (is_prefix_of(".ctors.", name)
1074 || is_prefix_of(".dtors.", name)
1075 || is_prefix_of(".init_array.", name)
1076 || is_prefix_of(".fini_array.", name)
1077 || (parameters->options().ctors_in_init_array()
1078 && (strcmp(name, ".ctors") == 0
1079 || strcmp(name, ".dtors") == 0))))
1080 os->set_must_sort_attached_input_sections();
1082 // If this is a .ctors or .ctors.* section being mapped to a
1083 // .init_array section, or a .dtors or .dtors.* section being mapped
1084 // to a .fini_array section, we will need to reverse the words if
1085 // there is more than one. Record this section for later. See
1086 // ctors_sections_in_init_array above.
1087 if (!this->script_options_->saw_sections_clause()
1088 && !parameters->options().relocatable()
1089 && shdr.get_sh_size() > size / 8
1090 && (((strcmp(name, ".ctors") == 0
1091 || is_prefix_of(".ctors.", name))
1092 && strcmp(os->name(), ".init_array") == 0)
1093 || ((strcmp(name, ".dtors") == 0
1094 || is_prefix_of(".dtors.", name))
1095 && strcmp(os->name(), ".fini_array") == 0)))
1096 ctors_sections_in_init_array.insert(Section_id(object, shndx));
1098 // FIXME: Handle SHF_LINK_ORDER somewhere.
1100 elfcpp::Elf_Xword orig_flags = os->flags();
1102 *off = os->add_input_section(this, object, shndx, name, shdr, reloc_shndx,
1103 this->script_options_->saw_sections_clause());
1105 // If the flags changed, we may have to change the order.
1106 if ((orig_flags & elfcpp::SHF_ALLOC) != 0)
1108 orig_flags &= (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR);
1109 elfcpp::Elf_Xword new_flags =
1110 os->flags() & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR);
1111 if (orig_flags != new_flags)
1112 os->set_order(this->default_section_order(os, false));
1115 this->have_added_input_section_ = true;
1120 // Handle a relocation section when doing a relocatable link.
1122 template<int size, bool big_endian>
1124 Layout::layout_reloc(Sized_relobj_file<size, big_endian>* object,
1126 const elfcpp::Shdr<size, big_endian>& shdr,
1127 Output_section* data_section,
1128 Relocatable_relocs* rr)
1130 gold_assert(parameters->options().relocatable()
1131 || parameters->options().emit_relocs());
1133 int sh_type = shdr.get_sh_type();
1136 if (sh_type == elfcpp::SHT_REL)
1138 else if (sh_type == elfcpp::SHT_RELA)
1142 name += data_section->name();
1144 // In a relocatable link relocs for a grouped section must not be
1145 // combined with other reloc sections.
1147 if (!parameters->options().relocatable()
1148 || (data_section->flags() & elfcpp::SHF_GROUP) == 0)
1149 os = this->choose_output_section(object, name.c_str(), sh_type,
1150 shdr.get_sh_flags(), false,
1151 ORDER_INVALID, false);
1154 const char* n = this->namepool_.add(name.c_str(), true, NULL);
1155 os = this->make_output_section(n, sh_type, shdr.get_sh_flags(),
1156 ORDER_INVALID, false);
1159 os->set_should_link_to_symtab();
1160 os->set_info_section(data_section);
1162 Output_section_data* posd;
1163 if (sh_type == elfcpp::SHT_REL)
1165 os->set_entsize(elfcpp::Elf_sizes<size>::rel_size);
1166 posd = new Output_relocatable_relocs<elfcpp::SHT_REL,
1170 else if (sh_type == elfcpp::SHT_RELA)
1172 os->set_entsize(elfcpp::Elf_sizes<size>::rela_size);
1173 posd = new Output_relocatable_relocs<elfcpp::SHT_RELA,
1180 os->add_output_section_data(posd);
1181 rr->set_output_data(posd);
1186 // Handle a group section when doing a relocatable link.
1188 template<int size, bool big_endian>
1190 Layout::layout_group(Symbol_table* symtab,
1191 Sized_relobj_file<size, big_endian>* object,
1193 const char* group_section_name,
1194 const char* signature,
1195 const elfcpp::Shdr<size, big_endian>& shdr,
1196 elfcpp::Elf_Word flags,
1197 std::vector<unsigned int>* shndxes)
1199 gold_assert(parameters->options().relocatable());
1200 gold_assert(shdr.get_sh_type() == elfcpp::SHT_GROUP);
1201 group_section_name = this->namepool_.add(group_section_name, true, NULL);
1202 Output_section* os = this->make_output_section(group_section_name,
1204 shdr.get_sh_flags(),
1205 ORDER_INVALID, false);
1207 // We need to find a symbol with the signature in the symbol table.
1208 // If we don't find one now, we need to look again later.
1209 Symbol* sym = symtab->lookup(signature, NULL);
1211 os->set_info_symndx(sym);
1214 // Reserve some space to minimize reallocations.
1215 if (this->group_signatures_.empty())
1216 this->group_signatures_.reserve(this->number_of_input_files_ * 16);
1218 // We will wind up using a symbol whose name is the signature.
1219 // So just put the signature in the symbol name pool to save it.
1220 signature = symtab->canonicalize_name(signature);
1221 this->group_signatures_.push_back(Group_signature(os, signature));
1224 os->set_should_link_to_symtab();
1227 section_size_type entry_count =
1228 convert_to_section_size_type(shdr.get_sh_size() / 4);
1229 Output_section_data* posd =
1230 new Output_data_group<size, big_endian>(object, entry_count, flags,
1232 os->add_output_section_data(posd);
1235 // Special GNU handling of sections name .eh_frame. They will
1236 // normally hold exception frame data as defined by the C++ ABI
1237 // (http://codesourcery.com/cxx-abi/).
1239 template<int size, bool big_endian>
1241 Layout::layout_eh_frame(Sized_relobj_file<size, big_endian>* object,
1242 const unsigned char* symbols,
1244 const unsigned char* symbol_names,
1245 off_t symbol_names_size,
1247 const elfcpp::Shdr<size, big_endian>& shdr,
1248 unsigned int reloc_shndx, unsigned int reloc_type,
1251 gold_assert(shdr.get_sh_type() == elfcpp::SHT_PROGBITS
1252 || shdr.get_sh_type() == elfcpp::SHT_X86_64_UNWIND);
1253 gold_assert((shdr.get_sh_flags() & elfcpp::SHF_ALLOC) != 0);
1255 Output_section* os = this->make_eh_frame_section(object);
1259 gold_assert(this->eh_frame_section_ == os);
1261 elfcpp::Elf_Xword orig_flags = os->flags();
1263 if (!parameters->incremental()
1264 && this->eh_frame_data_->add_ehframe_input_section(object,
1273 os->update_flags_for_input_section(shdr.get_sh_flags());
1275 // A writable .eh_frame section is a RELRO section.
1276 if ((orig_flags & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR))
1277 != (os->flags() & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR)))
1280 os->set_order(ORDER_RELRO);
1283 // We found a .eh_frame section we are going to optimize, so now
1284 // we can add the set of optimized sections to the output
1285 // section. We need to postpone adding this until we've found a
1286 // section we can optimize so that the .eh_frame section in
1287 // crtbegin.o winds up at the start of the output section.
1288 if (!this->added_eh_frame_data_)
1290 os->add_output_section_data(this->eh_frame_data_);
1291 this->added_eh_frame_data_ = true;
1297 // We couldn't handle this .eh_frame section for some reason.
1298 // Add it as a normal section.
1299 bool saw_sections_clause = this->script_options_->saw_sections_clause();
1300 *off = os->add_input_section(this, object, shndx, ".eh_frame", shdr,
1301 reloc_shndx, saw_sections_clause);
1302 this->have_added_input_section_ = true;
1304 if ((orig_flags & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR))
1305 != (os->flags() & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR)))
1306 os->set_order(this->default_section_order(os, false));
1312 // Create and return the magic .eh_frame section. Create
1313 // .eh_frame_hdr also if appropriate. OBJECT is the object with the
1314 // input .eh_frame section; it may be NULL.
1317 Layout::make_eh_frame_section(const Relobj* object)
1319 // FIXME: On x86_64, this could use SHT_X86_64_UNWIND rather than
1321 Output_section* os = this->choose_output_section(object, ".eh_frame",
1322 elfcpp::SHT_PROGBITS,
1323 elfcpp::SHF_ALLOC, false,
1324 ORDER_EHFRAME, false);
1328 if (this->eh_frame_section_ == NULL)
1330 this->eh_frame_section_ = os;
1331 this->eh_frame_data_ = new Eh_frame();
1333 // For incremental linking, we do not optimize .eh_frame sections
1334 // or create a .eh_frame_hdr section.
1335 if (parameters->options().eh_frame_hdr() && !parameters->incremental())
1337 Output_section* hdr_os =
1338 this->choose_output_section(NULL, ".eh_frame_hdr",
1339 elfcpp::SHT_PROGBITS,
1340 elfcpp::SHF_ALLOC, false,
1341 ORDER_EHFRAME, false);
1345 Eh_frame_hdr* hdr_posd = new Eh_frame_hdr(os,
1346 this->eh_frame_data_);
1347 hdr_os->add_output_section_data(hdr_posd);
1349 hdr_os->set_after_input_sections();
1351 if (!this->script_options_->saw_phdrs_clause())
1353 Output_segment* hdr_oseg;
1354 hdr_oseg = this->make_output_segment(elfcpp::PT_GNU_EH_FRAME,
1356 hdr_oseg->add_output_section_to_nonload(hdr_os,
1360 this->eh_frame_data_->set_eh_frame_hdr(hdr_posd);
1368 // Add an exception frame for a PLT. This is called from target code.
1371 Layout::add_eh_frame_for_plt(Output_data* plt, const unsigned char* cie_data,
1372 size_t cie_length, const unsigned char* fde_data,
1375 if (parameters->incremental())
1377 // FIXME: Maybe this could work some day....
1380 Output_section* os = this->make_eh_frame_section(NULL);
1383 this->eh_frame_data_->add_ehframe_for_plt(plt, cie_data, cie_length,
1384 fde_data, fde_length);
1385 if (!this->added_eh_frame_data_)
1387 os->add_output_section_data(this->eh_frame_data_);
1388 this->added_eh_frame_data_ = true;
1392 // Scan a .debug_info or .debug_types section, and add summary
1393 // information to the .gdb_index section.
1395 template<int size, bool big_endian>
1397 Layout::add_to_gdb_index(bool is_type_unit,
1398 Sized_relobj<size, big_endian>* object,
1399 const unsigned char* symbols,
1402 unsigned int reloc_shndx,
1403 unsigned int reloc_type)
1405 if (this->gdb_index_data_ == NULL)
1407 Output_section* os = this->choose_output_section(NULL, ".gdb_index",
1408 elfcpp::SHT_PROGBITS, 0,
1409 false, ORDER_INVALID,
1414 this->gdb_index_data_ = new Gdb_index(os);
1415 os->add_output_section_data(this->gdb_index_data_);
1416 os->set_after_input_sections();
1419 this->gdb_index_data_->scan_debug_info(is_type_unit, object, symbols,
1420 symbols_size, shndx, reloc_shndx,
1424 // Add POSD to an output section using NAME, TYPE, and FLAGS. Return
1425 // the output section.
1428 Layout::add_output_section_data(const char* name, elfcpp::Elf_Word type,
1429 elfcpp::Elf_Xword flags,
1430 Output_section_data* posd,
1431 Output_section_order order, bool is_relro)
1433 Output_section* os = this->choose_output_section(NULL, name, type, flags,
1434 false, order, is_relro);
1436 os->add_output_section_data(posd);
1440 // Map section flags to segment flags.
1443 Layout::section_flags_to_segment(elfcpp::Elf_Xword flags)
1445 elfcpp::Elf_Word ret = elfcpp::PF_R;
1446 if ((flags & elfcpp::SHF_WRITE) != 0)
1447 ret |= elfcpp::PF_W;
1448 if ((flags & elfcpp::SHF_EXECINSTR) != 0)
1449 ret |= elfcpp::PF_X;
1453 // Make a new Output_section, and attach it to segments as
1454 // appropriate. ORDER is the order in which this section should
1455 // appear in the output segment. IS_RELRO is true if this is a relro
1456 // (read-only after relocations) section.
1459 Layout::make_output_section(const char* name, elfcpp::Elf_Word type,
1460 elfcpp::Elf_Xword flags,
1461 Output_section_order order, bool is_relro)
1464 if ((flags & elfcpp::SHF_ALLOC) == 0
1465 && strcmp(parameters->options().compress_debug_sections(), "none") != 0
1466 && is_compressible_debug_section(name))
1467 os = new Output_compressed_section(¶meters->options(), name, type,
1469 else if ((flags & elfcpp::SHF_ALLOC) == 0
1470 && parameters->options().strip_debug_non_line()
1471 && strcmp(".debug_abbrev", name) == 0)
1473 os = this->debug_abbrev_ = new Output_reduced_debug_abbrev_section(
1475 if (this->debug_info_)
1476 this->debug_info_->set_abbreviations(this->debug_abbrev_);
1478 else if ((flags & elfcpp::SHF_ALLOC) == 0
1479 && parameters->options().strip_debug_non_line()
1480 && strcmp(".debug_info", name) == 0)
1482 os = this->debug_info_ = new Output_reduced_debug_info_section(
1484 if (this->debug_abbrev_)
1485 this->debug_info_->set_abbreviations(this->debug_abbrev_);
1489 // Sometimes .init_array*, .preinit_array* and .fini_array* do
1490 // not have correct section types. Force them here.
1491 if (type == elfcpp::SHT_PROGBITS)
1493 if (is_prefix_of(".init_array", name))
1494 type = elfcpp::SHT_INIT_ARRAY;
1495 else if (is_prefix_of(".preinit_array", name))
1496 type = elfcpp::SHT_PREINIT_ARRAY;
1497 else if (is_prefix_of(".fini_array", name))
1498 type = elfcpp::SHT_FINI_ARRAY;
1501 // FIXME: const_cast is ugly.
1502 Target* target = const_cast<Target*>(¶meters->target());
1503 os = target->make_output_section(name, type, flags);
1506 // With -z relro, we have to recognize the special sections by name.
1507 // There is no other way.
1508 bool is_relro_local = false;
1509 if (!this->script_options_->saw_sections_clause()
1510 && parameters->options().relro()
1511 && (flags & elfcpp::SHF_ALLOC) != 0
1512 && (flags & elfcpp::SHF_WRITE) != 0)
1514 if (type == elfcpp::SHT_PROGBITS)
1516 if ((flags & elfcpp::SHF_TLS) != 0)
1518 else if (strcmp(name, ".data.rel.ro") == 0)
1520 else if (strcmp(name, ".data.rel.ro.local") == 0)
1523 is_relro_local = true;
1525 else if (strcmp(name, ".ctors") == 0
1526 || strcmp(name, ".dtors") == 0
1527 || strcmp(name, ".jcr") == 0)
1530 else if (type == elfcpp::SHT_INIT_ARRAY
1531 || type == elfcpp::SHT_FINI_ARRAY
1532 || type == elfcpp::SHT_PREINIT_ARRAY)
1539 if (order == ORDER_INVALID && (flags & elfcpp::SHF_ALLOC) != 0)
1540 order = this->default_section_order(os, is_relro_local);
1542 os->set_order(order);
1544 parameters->target().new_output_section(os);
1546 this->section_list_.push_back(os);
1548 // The GNU linker by default sorts some sections by priority, so we
1549 // do the same. We need to know that this might happen before we
1550 // attach any input sections.
1551 if (!this->script_options_->saw_sections_clause()
1552 && !parameters->options().relocatable()
1553 && (strcmp(name, ".init_array") == 0
1554 || strcmp(name, ".fini_array") == 0
1555 || (!parameters->options().ctors_in_init_array()
1556 && (strcmp(name, ".ctors") == 0
1557 || strcmp(name, ".dtors") == 0))))
1558 os->set_may_sort_attached_input_sections();
1560 // Check for .stab*str sections, as .stab* sections need to link to
1562 if (type == elfcpp::SHT_STRTAB
1563 && !this->have_stabstr_section_
1564 && strncmp(name, ".stab", 5) == 0
1565 && strcmp(name + strlen(name) - 3, "str") == 0)
1566 this->have_stabstr_section_ = true;
1568 // During a full incremental link, we add patch space to most
1569 // PROGBITS and NOBITS sections. Flag those that may be
1570 // arbitrarily padded.
1571 if ((type == elfcpp::SHT_PROGBITS || type == elfcpp::SHT_NOBITS)
1572 && order != ORDER_INTERP
1573 && order != ORDER_INIT
1574 && order != ORDER_PLT
1575 && order != ORDER_FINI
1576 && order != ORDER_RELRO_LAST
1577 && order != ORDER_NON_RELRO_FIRST
1578 && strcmp(name, ".eh_frame") != 0
1579 && strcmp(name, ".ctors") != 0
1580 && strcmp(name, ".dtors") != 0
1581 && strcmp(name, ".jcr") != 0)
1583 os->set_is_patch_space_allowed();
1585 // Certain sections require "holes" to be filled with
1586 // specific fill patterns. These fill patterns may have
1587 // a minimum size, so we must prevent allocations from the
1588 // free list that leave a hole smaller than the minimum.
1589 if (strcmp(name, ".debug_info") == 0)
1590 os->set_free_space_fill(new Output_fill_debug_info(false));
1591 else if (strcmp(name, ".debug_types") == 0)
1592 os->set_free_space_fill(new Output_fill_debug_info(true));
1593 else if (strcmp(name, ".debug_line") == 0)
1594 os->set_free_space_fill(new Output_fill_debug_line());
1597 // If we have already attached the sections to segments, then we
1598 // need to attach this one now. This happens for sections created
1599 // directly by the linker.
1600 if (this->sections_are_attached_)
1601 this->attach_section_to_segment(¶meters->target(), os);
1606 // Return the default order in which a section should be placed in an
1607 // output segment. This function captures a lot of the ideas in
1608 // ld/scripttempl/elf.sc in the GNU linker. Note that the order of a
1609 // linker created section is normally set when the section is created;
1610 // this function is used for input sections.
1612 Output_section_order
1613 Layout::default_section_order(Output_section* os, bool is_relro_local)
1615 gold_assert((os->flags() & elfcpp::SHF_ALLOC) != 0);
1616 bool is_write = (os->flags() & elfcpp::SHF_WRITE) != 0;
1617 bool is_execinstr = (os->flags() & elfcpp::SHF_EXECINSTR) != 0;
1618 bool is_bss = false;
1623 case elfcpp::SHT_PROGBITS:
1625 case elfcpp::SHT_NOBITS:
1628 case elfcpp::SHT_RELA:
1629 case elfcpp::SHT_REL:
1631 return ORDER_DYNAMIC_RELOCS;
1633 case elfcpp::SHT_HASH:
1634 case elfcpp::SHT_DYNAMIC:
1635 case elfcpp::SHT_SHLIB:
1636 case elfcpp::SHT_DYNSYM:
1637 case elfcpp::SHT_GNU_HASH:
1638 case elfcpp::SHT_GNU_verdef:
1639 case elfcpp::SHT_GNU_verneed:
1640 case elfcpp::SHT_GNU_versym:
1642 return ORDER_DYNAMIC_LINKER;
1644 case elfcpp::SHT_NOTE:
1645 return is_write ? ORDER_RW_NOTE : ORDER_RO_NOTE;
1648 if ((os->flags() & elfcpp::SHF_TLS) != 0)
1649 return is_bss ? ORDER_TLS_BSS : ORDER_TLS_DATA;
1651 if (!is_bss && !is_write)
1655 if (strcmp(os->name(), ".init") == 0)
1657 else if (strcmp(os->name(), ".fini") == 0)
1660 return is_execinstr ? ORDER_TEXT : ORDER_READONLY;
1664 return is_relro_local ? ORDER_RELRO_LOCAL : ORDER_RELRO;
1666 if (os->is_small_section())
1667 return is_bss ? ORDER_SMALL_BSS : ORDER_SMALL_DATA;
1668 if (os->is_large_section())
1669 return is_bss ? ORDER_LARGE_BSS : ORDER_LARGE_DATA;
1671 return is_bss ? ORDER_BSS : ORDER_DATA;
1674 // Attach output sections to segments. This is called after we have
1675 // seen all the input sections.
1678 Layout::attach_sections_to_segments(const Target* target)
1680 for (Section_list::iterator p = this->section_list_.begin();
1681 p != this->section_list_.end();
1683 this->attach_section_to_segment(target, *p);
1685 this->sections_are_attached_ = true;
1688 // Attach an output section to a segment.
1691 Layout::attach_section_to_segment(const Target* target, Output_section* os)
1693 if ((os->flags() & elfcpp::SHF_ALLOC) == 0)
1694 this->unattached_section_list_.push_back(os);
1696 this->attach_allocated_section_to_segment(target, os);
1699 // Attach an allocated output section to a segment.
1702 Layout::attach_allocated_section_to_segment(const Target* target,
1705 elfcpp::Elf_Xword flags = os->flags();
1706 gold_assert((flags & elfcpp::SHF_ALLOC) != 0);
1708 if (parameters->options().relocatable())
1711 // If we have a SECTIONS clause, we can't handle the attachment to
1712 // segments until after we've seen all the sections.
1713 if (this->script_options_->saw_sections_clause())
1716 gold_assert(!this->script_options_->saw_phdrs_clause());
1718 // This output section goes into a PT_LOAD segment.
1720 elfcpp::Elf_Word seg_flags = Layout::section_flags_to_segment(flags);
1722 // Check for --section-start.
1724 bool is_address_set = parameters->options().section_start(os->name(), &addr);
1726 // In general the only thing we really care about for PT_LOAD
1727 // segments is whether or not they are writable or executable,
1728 // so that is how we search for them.
1729 // Large data sections also go into their own PT_LOAD segment.
1730 // People who need segments sorted on some other basis will
1731 // have to use a linker script.
1733 Segment_list::const_iterator p;
1734 for (p = this->segment_list_.begin();
1735 p != this->segment_list_.end();
1738 if ((*p)->type() != elfcpp::PT_LOAD)
1740 if (!parameters->options().omagic()
1741 && ((*p)->flags() & elfcpp::PF_W) != (seg_flags & elfcpp::PF_W))
1743 if ((target->isolate_execinstr() || parameters->options().rosegment())
1744 && ((*p)->flags() & elfcpp::PF_X) != (seg_flags & elfcpp::PF_X))
1746 // If -Tbss was specified, we need to separate the data and BSS
1748 if (parameters->options().user_set_Tbss())
1750 if ((os->type() == elfcpp::SHT_NOBITS)
1751 == (*p)->has_any_data_sections())
1754 if (os->is_large_data_section() && !(*p)->is_large_data_segment())
1759 if ((*p)->are_addresses_set())
1762 (*p)->add_initial_output_data(os);
1763 (*p)->update_flags_for_output_section(seg_flags);
1764 (*p)->set_addresses(addr, addr);
1768 (*p)->add_output_section_to_load(this, os, seg_flags);
1772 if (p == this->segment_list_.end())
1774 Output_segment* oseg = this->make_output_segment(elfcpp::PT_LOAD,
1776 if (os->is_large_data_section())
1777 oseg->set_is_large_data_segment();
1778 oseg->add_output_section_to_load(this, os, seg_flags);
1780 oseg->set_addresses(addr, addr);
1783 // If we see a loadable SHT_NOTE section, we create a PT_NOTE
1785 if (os->type() == elfcpp::SHT_NOTE)
1787 // See if we already have an equivalent PT_NOTE segment.
1788 for (p = this->segment_list_.begin();
1789 p != segment_list_.end();
1792 if ((*p)->type() == elfcpp::PT_NOTE
1793 && (((*p)->flags() & elfcpp::PF_W)
1794 == (seg_flags & elfcpp::PF_W)))
1796 (*p)->add_output_section_to_nonload(os, seg_flags);
1801 if (p == this->segment_list_.end())
1803 Output_segment* oseg = this->make_output_segment(elfcpp::PT_NOTE,
1805 oseg->add_output_section_to_nonload(os, seg_flags);
1809 // If we see a loadable SHF_TLS section, we create a PT_TLS
1810 // segment. There can only be one such segment.
1811 if ((flags & elfcpp::SHF_TLS) != 0)
1813 if (this->tls_segment_ == NULL)
1814 this->make_output_segment(elfcpp::PT_TLS, seg_flags);
1815 this->tls_segment_->add_output_section_to_nonload(os, seg_flags);
1818 // If -z relro is in effect, and we see a relro section, we create a
1819 // PT_GNU_RELRO segment. There can only be one such segment.
1820 if (os->is_relro() && parameters->options().relro())
1822 gold_assert(seg_flags == (elfcpp::PF_R | elfcpp::PF_W));
1823 if (this->relro_segment_ == NULL)
1824 this->make_output_segment(elfcpp::PT_GNU_RELRO, seg_flags);
1825 this->relro_segment_->add_output_section_to_nonload(os, seg_flags);
1828 // If we see a section named .interp, put it into a PT_INTERP
1829 // segment. This seems broken to me, but this is what GNU ld does,
1830 // and glibc expects it.
1831 if (strcmp(os->name(), ".interp") == 0
1832 && !this->script_options_->saw_phdrs_clause())
1834 if (this->interp_segment_ == NULL)
1835 this->make_output_segment(elfcpp::PT_INTERP, seg_flags);
1837 gold_warning(_("multiple '.interp' sections in input files "
1838 "may cause confusing PT_INTERP segment"));
1839 this->interp_segment_->add_output_section_to_nonload(os, seg_flags);
1843 // Make an output section for a script.
1846 Layout::make_output_section_for_script(
1848 Script_sections::Section_type section_type)
1850 name = this->namepool_.add(name, false, NULL);
1851 elfcpp::Elf_Xword sh_flags = elfcpp::SHF_ALLOC;
1852 if (section_type == Script_sections::ST_NOLOAD)
1854 Output_section* os = this->make_output_section(name, elfcpp::SHT_PROGBITS,
1855 sh_flags, ORDER_INVALID,
1857 os->set_found_in_sections_clause();
1858 if (section_type == Script_sections::ST_NOLOAD)
1859 os->set_is_noload();
1863 // Return the number of segments we expect to see.
1866 Layout::expected_segment_count() const
1868 size_t ret = this->segment_list_.size();
1870 // If we didn't see a SECTIONS clause in a linker script, we should
1871 // already have the complete list of segments. Otherwise we ask the
1872 // SECTIONS clause how many segments it expects, and add in the ones
1873 // we already have (PT_GNU_STACK, PT_GNU_EH_FRAME, etc.)
1875 if (!this->script_options_->saw_sections_clause())
1879 const Script_sections* ss = this->script_options_->script_sections();
1880 return ret + ss->expected_segment_count(this);
1884 // Handle the .note.GNU-stack section at layout time. SEEN_GNU_STACK
1885 // is whether we saw a .note.GNU-stack section in the object file.
1886 // GNU_STACK_FLAGS is the section flags. The flags give the
1887 // protection required for stack memory. We record this in an
1888 // executable as a PT_GNU_STACK segment. If an object file does not
1889 // have a .note.GNU-stack segment, we must assume that it is an old
1890 // object. On some targets that will force an executable stack.
1893 Layout::layout_gnu_stack(bool seen_gnu_stack, uint64_t gnu_stack_flags,
1896 if (!seen_gnu_stack)
1898 this->input_without_gnu_stack_note_ = true;
1899 if (parameters->options().warn_execstack()
1900 && parameters->target().is_default_stack_executable())
1901 gold_warning(_("%s: missing .note.GNU-stack section"
1902 " implies executable stack"),
1903 obj->name().c_str());
1907 this->input_with_gnu_stack_note_ = true;
1908 if ((gnu_stack_flags & elfcpp::SHF_EXECINSTR) != 0)
1910 this->input_requires_executable_stack_ = true;
1911 if (parameters->options().warn_execstack()
1912 || parameters->options().is_stack_executable())
1913 gold_warning(_("%s: requires executable stack"),
1914 obj->name().c_str());
1919 // Create automatic note sections.
1922 Layout::create_notes()
1924 this->create_gold_note();
1925 this->create_executable_stack_info();
1926 this->create_build_id();
1929 // Create the dynamic sections which are needed before we read the
1933 Layout::create_initial_dynamic_sections(Symbol_table* symtab)
1935 if (parameters->doing_static_link())
1938 this->dynamic_section_ = this->choose_output_section(NULL, ".dynamic",
1939 elfcpp::SHT_DYNAMIC,
1941 | elfcpp::SHF_WRITE),
1945 // A linker script may discard .dynamic, so check for NULL.
1946 if (this->dynamic_section_ != NULL)
1948 this->dynamic_symbol_ =
1949 symtab->define_in_output_data("_DYNAMIC", NULL,
1950 Symbol_table::PREDEFINED,
1951 this->dynamic_section_, 0, 0,
1952 elfcpp::STT_OBJECT, elfcpp::STB_LOCAL,
1953 elfcpp::STV_HIDDEN, 0, false, false);
1955 this->dynamic_data_ = new Output_data_dynamic(&this->dynpool_);
1957 this->dynamic_section_->add_output_section_data(this->dynamic_data_);
1961 // For each output section whose name can be represented as C symbol,
1962 // define __start and __stop symbols for the section. This is a GNU
1966 Layout::define_section_symbols(Symbol_table* symtab)
1968 for (Section_list::const_iterator p = this->section_list_.begin();
1969 p != this->section_list_.end();
1972 const char* const name = (*p)->name();
1973 if (is_cident(name))
1975 const std::string name_string(name);
1976 const std::string start_name(cident_section_start_prefix
1978 const std::string stop_name(cident_section_stop_prefix
1981 symtab->define_in_output_data(start_name.c_str(),
1983 Symbol_table::PREDEFINED,
1989 elfcpp::STV_DEFAULT,
1991 false, // offset_is_from_end
1992 true); // only_if_ref
1994 symtab->define_in_output_data(stop_name.c_str(),
1996 Symbol_table::PREDEFINED,
2002 elfcpp::STV_DEFAULT,
2004 true, // offset_is_from_end
2005 true); // only_if_ref
2010 // Define symbols for group signatures.
2013 Layout::define_group_signatures(Symbol_table* symtab)
2015 for (Group_signatures::iterator p = this->group_signatures_.begin();
2016 p != this->group_signatures_.end();
2019 Symbol* sym = symtab->lookup(p->signature, NULL);
2021 p->section->set_info_symndx(sym);
2024 // Force the name of the group section to the group
2025 // signature, and use the group's section symbol as the
2026 // signature symbol.
2027 if (strcmp(p->section->name(), p->signature) != 0)
2029 const char* name = this->namepool_.add(p->signature,
2031 p->section->set_name(name);
2033 p->section->set_needs_symtab_index();
2034 p->section->set_info_section_symndx(p->section);
2038 this->group_signatures_.clear();
2041 // Find the first read-only PT_LOAD segment, creating one if
2045 Layout::find_first_load_seg(const Target* target)
2047 Output_segment* best = NULL;
2048 for (Segment_list::const_iterator p = this->segment_list_.begin();
2049 p != this->segment_list_.end();
2052 if ((*p)->type() == elfcpp::PT_LOAD
2053 && ((*p)->flags() & elfcpp::PF_R) != 0
2054 && (parameters->options().omagic()
2055 || ((*p)->flags() & elfcpp::PF_W) == 0)
2056 && (!target->isolate_execinstr()
2057 || ((*p)->flags() & elfcpp::PF_X) == 0))
2059 if (best == NULL || this->segment_precedes(*p, best))
2066 gold_assert(!this->script_options_->saw_phdrs_clause());
2068 Output_segment* load_seg = this->make_output_segment(elfcpp::PT_LOAD,
2073 // Save states of all current output segments. Store saved states
2074 // in SEGMENT_STATES.
2077 Layout::save_segments(Segment_states* segment_states)
2079 for (Segment_list::const_iterator p = this->segment_list_.begin();
2080 p != this->segment_list_.end();
2083 Output_segment* segment = *p;
2085 Output_segment* copy = new Output_segment(*segment);
2086 (*segment_states)[segment] = copy;
2090 // Restore states of output segments and delete any segment not found in
2094 Layout::restore_segments(const Segment_states* segment_states)
2096 // Go through the segment list and remove any segment added in the
2098 this->tls_segment_ = NULL;
2099 this->relro_segment_ = NULL;
2100 Segment_list::iterator list_iter = this->segment_list_.begin();
2101 while (list_iter != this->segment_list_.end())
2103 Output_segment* segment = *list_iter;
2104 Segment_states::const_iterator states_iter =
2105 segment_states->find(segment);
2106 if (states_iter != segment_states->end())
2108 const Output_segment* copy = states_iter->second;
2109 // Shallow copy to restore states.
2112 // Also fix up TLS and RELRO segment pointers as appropriate.
2113 if (segment->type() == elfcpp::PT_TLS)
2114 this->tls_segment_ = segment;
2115 else if (segment->type() == elfcpp::PT_GNU_RELRO)
2116 this->relro_segment_ = segment;
2122 list_iter = this->segment_list_.erase(list_iter);
2123 // This is a segment created during section layout. It should be
2124 // safe to remove it since we should have removed all pointers to it.
2130 // Clean up after relaxation so that sections can be laid out again.
2133 Layout::clean_up_after_relaxation()
2135 // Restore the segments to point state just prior to the relaxation loop.
2136 Script_sections* script_section = this->script_options_->script_sections();
2137 script_section->release_segments();
2138 this->restore_segments(this->segment_states_);
2140 // Reset section addresses and file offsets
2141 for (Section_list::iterator p = this->section_list_.begin();
2142 p != this->section_list_.end();
2145 (*p)->restore_states();
2147 // If an input section changes size because of relaxation,
2148 // we need to adjust the section offsets of all input sections.
2149 // after such a section.
2150 if ((*p)->section_offsets_need_adjustment())
2151 (*p)->adjust_section_offsets();
2153 (*p)->reset_address_and_file_offset();
2156 // Reset special output object address and file offsets.
2157 for (Data_list::iterator p = this->special_output_list_.begin();
2158 p != this->special_output_list_.end();
2160 (*p)->reset_address_and_file_offset();
2162 // A linker script may have created some output section data objects.
2163 // They are useless now.
2164 for (Output_section_data_list::const_iterator p =
2165 this->script_output_section_data_list_.begin();
2166 p != this->script_output_section_data_list_.end();
2169 this->script_output_section_data_list_.clear();
2172 // Prepare for relaxation.
2175 Layout::prepare_for_relaxation()
2177 // Create an relaxation debug check if in debugging mode.
2178 if (is_debugging_enabled(DEBUG_RELAXATION))
2179 this->relaxation_debug_check_ = new Relaxation_debug_check();
2181 // Save segment states.
2182 this->segment_states_ = new Segment_states();
2183 this->save_segments(this->segment_states_);
2185 for(Section_list::const_iterator p = this->section_list_.begin();
2186 p != this->section_list_.end();
2188 (*p)->save_states();
2190 if (is_debugging_enabled(DEBUG_RELAXATION))
2191 this->relaxation_debug_check_->check_output_data_for_reset_values(
2192 this->section_list_, this->special_output_list_);
2194 // Also enable recording of output section data from scripts.
2195 this->record_output_section_data_from_script_ = true;
2198 // Relaxation loop body: If target has no relaxation, this runs only once
2199 // Otherwise, the target relaxation hook is called at the end of
2200 // each iteration. If the hook returns true, it means re-layout of
2201 // section is required.
2203 // The number of segments created by a linking script without a PHDRS
2204 // clause may be affected by section sizes and alignments. There is
2205 // a remote chance that relaxation causes different number of PT_LOAD
2206 // segments are created and sections are attached to different segments.
2207 // Therefore, we always throw away all segments created during section
2208 // layout. In order to be able to restart the section layout, we keep
2209 // a copy of the segment list right before the relaxation loop and use
2210 // that to restore the segments.
2212 // PASS is the current relaxation pass number.
2213 // SYMTAB is a symbol table.
2214 // PLOAD_SEG is the address of a pointer for the load segment.
2215 // PHDR_SEG is a pointer to the PHDR segment.
2216 // SEGMENT_HEADERS points to the output segment header.
2217 // FILE_HEADER points to the output file header.
2218 // PSHNDX is the address to store the output section index.
2221 Layout::relaxation_loop_body(
2224 Symbol_table* symtab,
2225 Output_segment** pload_seg,
2226 Output_segment* phdr_seg,
2227 Output_segment_headers* segment_headers,
2228 Output_file_header* file_header,
2229 unsigned int* pshndx)
2231 // If this is not the first iteration, we need to clean up after
2232 // relaxation so that we can lay out the sections again.
2234 this->clean_up_after_relaxation();
2236 // If there is a SECTIONS clause, put all the input sections into
2237 // the required order.
2238 Output_segment* load_seg;
2239 if (this->script_options_->saw_sections_clause())
2240 load_seg = this->set_section_addresses_from_script(symtab);
2241 else if (parameters->options().relocatable())
2244 load_seg = this->find_first_load_seg(target);
2246 if (parameters->options().oformat_enum()
2247 != General_options::OBJECT_FORMAT_ELF)
2250 // If the user set the address of the text segment, that may not be
2251 // compatible with putting the segment headers and file headers into
2253 if (parameters->options().user_set_Ttext()
2254 && parameters->options().Ttext() % target->common_pagesize() != 0)
2260 gold_assert(phdr_seg == NULL
2262 || this->script_options_->saw_sections_clause());
2264 // If the address of the load segment we found has been set by
2265 // --section-start rather than by a script, then adjust the VMA and
2266 // LMA downward if possible to include the file and section headers.
2267 uint64_t header_gap = 0;
2268 if (load_seg != NULL
2269 && load_seg->are_addresses_set()
2270 && !this->script_options_->saw_sections_clause()
2271 && !parameters->options().relocatable())
2273 file_header->finalize_data_size();
2274 segment_headers->finalize_data_size();
2275 size_t sizeof_headers = (file_header->data_size()
2276 + segment_headers->data_size());
2277 const uint64_t abi_pagesize = target->abi_pagesize();
2278 uint64_t hdr_paddr = load_seg->paddr() - sizeof_headers;
2279 hdr_paddr &= ~(abi_pagesize - 1);
2280 uint64_t subtract = load_seg->paddr() - hdr_paddr;
2281 if (load_seg->paddr() < subtract || load_seg->vaddr() < subtract)
2285 load_seg->set_addresses(load_seg->vaddr() - subtract,
2286 load_seg->paddr() - subtract);
2287 header_gap = subtract - sizeof_headers;
2291 // Lay out the segment headers.
2292 if (!parameters->options().relocatable())
2294 gold_assert(segment_headers != NULL);
2295 if (header_gap != 0 && load_seg != NULL)
2297 Output_data_zero_fill* z = new Output_data_zero_fill(header_gap, 1);
2298 load_seg->add_initial_output_data(z);
2300 if (load_seg != NULL)
2301 load_seg->add_initial_output_data(segment_headers);
2302 if (phdr_seg != NULL)
2303 phdr_seg->add_initial_output_data(segment_headers);
2306 // Lay out the file header.
2307 if (load_seg != NULL)
2308 load_seg->add_initial_output_data(file_header);
2310 if (this->script_options_->saw_phdrs_clause()
2311 && !parameters->options().relocatable())
2313 // Support use of FILEHDRS and PHDRS attachments in a PHDRS
2314 // clause in a linker script.
2315 Script_sections* ss = this->script_options_->script_sections();
2316 ss->put_headers_in_phdrs(file_header, segment_headers);
2319 // We set the output section indexes in set_segment_offsets and
2320 // set_section_indexes.
2323 // Set the file offsets of all the segments, and all the sections
2326 if (!parameters->options().relocatable())
2327 off = this->set_segment_offsets(target, load_seg, pshndx);
2329 off = this->set_relocatable_section_offsets(file_header, pshndx);
2331 // Verify that the dummy relaxation does not change anything.
2332 if (is_debugging_enabled(DEBUG_RELAXATION))
2335 this->relaxation_debug_check_->read_sections(this->section_list_);
2337 this->relaxation_debug_check_->verify_sections(this->section_list_);
2340 *pload_seg = load_seg;
2344 // Search the list of patterns and find the postion of the given section
2345 // name in the output section. If the section name matches a glob
2346 // pattern and a non-glob name, then the non-glob position takes
2347 // precedence. Return 0 if no match is found.
2350 Layout::find_section_order_index(const std::string& section_name)
2352 Unordered_map<std::string, unsigned int>::iterator map_it;
2353 map_it = this->input_section_position_.find(section_name);
2354 if (map_it != this->input_section_position_.end())
2355 return map_it->second;
2357 // Absolute match failed. Linear search the glob patterns.
2358 std::vector<std::string>::iterator it;
2359 for (it = this->input_section_glob_.begin();
2360 it != this->input_section_glob_.end();
2363 if (fnmatch((*it).c_str(), section_name.c_str(), FNM_NOESCAPE) == 0)
2365 map_it = this->input_section_position_.find(*it);
2366 gold_assert(map_it != this->input_section_position_.end());
2367 return map_it->second;
2373 // Read the sequence of input sections from the file specified with
2374 // option --section-ordering-file.
2377 Layout::read_layout_from_file()
2379 const char* filename = parameters->options().section_ordering_file();
2385 gold_fatal(_("unable to open --section-ordering-file file %s: %s"),
2386 filename, strerror(errno));
2388 std::getline(in, line); // this chops off the trailing \n, if any
2389 unsigned int position = 1;
2390 this->set_section_ordering_specified();
2394 if (!line.empty() && line[line.length() - 1] == '\r') // Windows
2395 line.resize(line.length() - 1);
2396 // Ignore comments, beginning with '#'
2399 std::getline(in, line);
2402 this->input_section_position_[line] = position;
2403 // Store all glob patterns in a vector.
2404 if (is_wildcard_string(line.c_str()))
2405 this->input_section_glob_.push_back(line);
2407 std::getline(in, line);
2411 // Finalize the layout. When this is called, we have created all the
2412 // output sections and all the output segments which are based on
2413 // input sections. We have several things to do, and we have to do
2414 // them in the right order, so that we get the right results correctly
2417 // 1) Finalize the list of output segments and create the segment
2420 // 2) Finalize the dynamic symbol table and associated sections.
2422 // 3) Determine the final file offset of all the output segments.
2424 // 4) Determine the final file offset of all the SHF_ALLOC output
2427 // 5) Create the symbol table sections and the section name table
2430 // 6) Finalize the symbol table: set symbol values to their final
2431 // value and make a final determination of which symbols are going
2432 // into the output symbol table.
2434 // 7) Create the section table header.
2436 // 8) Determine the final file offset of all the output sections which
2437 // are not SHF_ALLOC, including the section table header.
2439 // 9) Finalize the ELF file header.
2441 // This function returns the size of the output file.
2444 Layout::finalize(const Input_objects* input_objects, Symbol_table* symtab,
2445 Target* target, const Task* task)
2447 target->finalize_sections(this, input_objects, symtab);
2449 this->count_local_symbols(task, input_objects);
2451 this->link_stabs_sections();
2453 Output_segment* phdr_seg = NULL;
2454 if (!parameters->options().relocatable() && !parameters->doing_static_link())
2456 // There was a dynamic object in the link. We need to create
2457 // some information for the dynamic linker.
2459 // Create the PT_PHDR segment which will hold the program
2461 if (!this->script_options_->saw_phdrs_clause())
2462 phdr_seg = this->make_output_segment(elfcpp::PT_PHDR, elfcpp::PF_R);
2464 // Create the dynamic symbol table, including the hash table.
2465 Output_section* dynstr;
2466 std::vector<Symbol*> dynamic_symbols;
2467 unsigned int local_dynamic_count;
2468 Versions versions(*this->script_options()->version_script_info(),
2470 this->create_dynamic_symtab(input_objects, symtab, &dynstr,
2471 &local_dynamic_count, &dynamic_symbols,
2474 // Create the .interp section to hold the name of the
2475 // interpreter, and put it in a PT_INTERP segment. Don't do it
2476 // if we saw a .interp section in an input file.
2477 if ((!parameters->options().shared()
2478 || parameters->options().dynamic_linker() != NULL)
2479 && this->interp_segment_ == NULL)
2480 this->create_interp(target);
2482 // Finish the .dynamic section to hold the dynamic data, and put
2483 // it in a PT_DYNAMIC segment.
2484 this->finish_dynamic_section(input_objects, symtab);
2486 // We should have added everything we need to the dynamic string
2488 this->dynpool_.set_string_offsets();
2490 // Create the version sections. We can't do this until the
2491 // dynamic string table is complete.
2492 this->create_version_sections(&versions, symtab, local_dynamic_count,
2493 dynamic_symbols, dynstr);
2495 // Set the size of the _DYNAMIC symbol. We can't do this until
2496 // after we call create_version_sections.
2497 this->set_dynamic_symbol_size(symtab);
2500 // Create segment headers.
2501 Output_segment_headers* segment_headers =
2502 (parameters->options().relocatable()
2504 : new Output_segment_headers(this->segment_list_));
2506 // Lay out the file header.
2507 Output_file_header* file_header = new Output_file_header(target, symtab,
2510 this->special_output_list_.push_back(file_header);
2511 if (segment_headers != NULL)
2512 this->special_output_list_.push_back(segment_headers);
2514 // Find approriate places for orphan output sections if we are using
2516 if (this->script_options_->saw_sections_clause())
2517 this->place_orphan_sections_in_script();
2519 Output_segment* load_seg;
2524 // Take a snapshot of the section layout as needed.
2525 if (target->may_relax())
2526 this->prepare_for_relaxation();
2528 // Run the relaxation loop to lay out sections.
2531 off = this->relaxation_loop_body(pass, target, symtab, &load_seg,
2532 phdr_seg, segment_headers, file_header,
2536 while (target->may_relax()
2537 && target->relax(pass, input_objects, symtab, this, task));
2539 // If there is a load segment that contains the file and program headers,
2540 // provide a symbol __ehdr_start pointing there.
2541 // A program can use this to examine itself robustly.
2542 if (load_seg != NULL)
2543 symtab->define_in_output_segment("__ehdr_start", NULL,
2544 Symbol_table::PREDEFINED, load_seg, 0, 0,
2545 elfcpp::STT_NOTYPE, elfcpp::STB_GLOBAL,
2546 elfcpp::STV_DEFAULT, 0,
2547 Symbol::SEGMENT_START, true);
2549 // Set the file offsets of all the non-data sections we've seen so
2550 // far which don't have to wait for the input sections. We need
2551 // this in order to finalize local symbols in non-allocated
2553 off = this->set_section_offsets(off, BEFORE_INPUT_SECTIONS_PASS);
2555 // Set the section indexes of all unallocated sections seen so far,
2556 // in case any of them are somehow referenced by a symbol.
2557 shndx = this->set_section_indexes(shndx);
2559 // Create the symbol table sections.
2560 this->create_symtab_sections(input_objects, symtab, shndx, &off);
2561 if (!parameters->doing_static_link())
2562 this->assign_local_dynsym_offsets(input_objects);
2564 // Process any symbol assignments from a linker script. This must
2565 // be called after the symbol table has been finalized.
2566 this->script_options_->finalize_symbols(symtab, this);
2568 // Create the incremental inputs sections.
2569 if (this->incremental_inputs_)
2571 this->incremental_inputs_->finalize();
2572 this->create_incremental_info_sections(symtab);
2575 // Create the .shstrtab section.
2576 Output_section* shstrtab_section = this->create_shstrtab();
2578 // Set the file offsets of the rest of the non-data sections which
2579 // don't have to wait for the input sections.
2580 off = this->set_section_offsets(off, BEFORE_INPUT_SECTIONS_PASS);
2582 // Now that all sections have been created, set the section indexes
2583 // for any sections which haven't been done yet.
2584 shndx = this->set_section_indexes(shndx);
2586 // Create the section table header.
2587 this->create_shdrs(shstrtab_section, &off);
2589 // If there are no sections which require postprocessing, we can
2590 // handle the section names now, and avoid a resize later.
2591 if (!this->any_postprocessing_sections_)
2593 off = this->set_section_offsets(off,
2594 POSTPROCESSING_SECTIONS_PASS);
2596 this->set_section_offsets(off,
2597 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS);
2600 file_header->set_section_info(this->section_headers_, shstrtab_section);
2602 // Now we know exactly where everything goes in the output file
2603 // (except for non-allocated sections which require postprocessing).
2604 Output_data::layout_complete();
2606 this->output_file_size_ = off;
2611 // Create a note header following the format defined in the ELF ABI.
2612 // NAME is the name, NOTE_TYPE is the type, SECTION_NAME is the name
2613 // of the section to create, DESCSZ is the size of the descriptor.
2614 // ALLOCATE is true if the section should be allocated in memory.
2615 // This returns the new note section. It sets *TRAILING_PADDING to
2616 // the number of trailing zero bytes required.
2619 Layout::create_note(const char* name, int note_type,
2620 const char* section_name, size_t descsz,
2621 bool allocate, size_t* trailing_padding)
2623 // Authorities all agree that the values in a .note field should
2624 // be aligned on 4-byte boundaries for 32-bit binaries. However,
2625 // they differ on what the alignment is for 64-bit binaries.
2626 // The GABI says unambiguously they take 8-byte alignment:
2627 // http://sco.com/developers/gabi/latest/ch5.pheader.html#note_section
2628 // Other documentation says alignment should always be 4 bytes:
2629 // http://www.netbsd.org/docs/kernel/elf-notes.html#note-format
2630 // GNU ld and GNU readelf both support the latter (at least as of
2631 // version 2.16.91), and glibc always generates the latter for
2632 // .note.ABI-tag (as of version 1.6), so that's the one we go with
2634 #ifdef GABI_FORMAT_FOR_DOTNOTE_SECTION // This is not defined by default.
2635 const int size = parameters->target().get_size();
2637 const int size = 32;
2640 // The contents of the .note section.
2641 size_t namesz = strlen(name) + 1;
2642 size_t aligned_namesz = align_address(namesz, size / 8);
2643 size_t aligned_descsz = align_address(descsz, size / 8);
2645 size_t notehdrsz = 3 * (size / 8) + aligned_namesz;
2647 unsigned char* buffer = new unsigned char[notehdrsz];
2648 memset(buffer, 0, notehdrsz);
2650 bool is_big_endian = parameters->target().is_big_endian();
2656 elfcpp::Swap<32, false>::writeval(buffer, namesz);
2657 elfcpp::Swap<32, false>::writeval(buffer + 4, descsz);
2658 elfcpp::Swap<32, false>::writeval(buffer + 8, note_type);
2662 elfcpp::Swap<32, true>::writeval(buffer, namesz);
2663 elfcpp::Swap<32, true>::writeval(buffer + 4, descsz);
2664 elfcpp::Swap<32, true>::writeval(buffer + 8, note_type);
2667 else if (size == 64)
2671 elfcpp::Swap<64, false>::writeval(buffer, namesz);
2672 elfcpp::Swap<64, false>::writeval(buffer + 8, descsz);
2673 elfcpp::Swap<64, false>::writeval(buffer + 16, note_type);
2677 elfcpp::Swap<64, true>::writeval(buffer, namesz);
2678 elfcpp::Swap<64, true>::writeval(buffer + 8, descsz);
2679 elfcpp::Swap<64, true>::writeval(buffer + 16, note_type);
2685 memcpy(buffer + 3 * (size / 8), name, namesz);
2687 elfcpp::Elf_Xword flags = 0;
2688 Output_section_order order = ORDER_INVALID;
2691 flags = elfcpp::SHF_ALLOC;
2692 order = ORDER_RO_NOTE;
2694 Output_section* os = this->choose_output_section(NULL, section_name,
2696 flags, false, order, false);
2700 Output_section_data* posd = new Output_data_const_buffer(buffer, notehdrsz,
2703 os->add_output_section_data(posd);
2705 *trailing_padding = aligned_descsz - descsz;
2710 // For an executable or shared library, create a note to record the
2711 // version of gold used to create the binary.
2714 Layout::create_gold_note()
2716 if (parameters->options().relocatable()
2717 || parameters->incremental_update())
2720 std::string desc = std::string("gold ") + gold::get_version_string();
2722 size_t trailing_padding;
2723 Output_section* os = this->create_note("GNU", elfcpp::NT_GNU_GOLD_VERSION,
2724 ".note.gnu.gold-version", desc.size(),
2725 false, &trailing_padding);
2729 Output_section_data* posd = new Output_data_const(desc, 4);
2730 os->add_output_section_data(posd);
2732 if (trailing_padding > 0)
2734 posd = new Output_data_zero_fill(trailing_padding, 0);
2735 os->add_output_section_data(posd);
2739 // Record whether the stack should be executable. This can be set
2740 // from the command line using the -z execstack or -z noexecstack
2741 // options. Otherwise, if any input file has a .note.GNU-stack
2742 // section with the SHF_EXECINSTR flag set, the stack should be
2743 // executable. Otherwise, if at least one input file a
2744 // .note.GNU-stack section, and some input file has no .note.GNU-stack
2745 // section, we use the target default for whether the stack should be
2746 // executable. Otherwise, we don't generate a stack note. When
2747 // generating a object file, we create a .note.GNU-stack section with
2748 // the appropriate marking. When generating an executable or shared
2749 // library, we create a PT_GNU_STACK segment.
2752 Layout::create_executable_stack_info()
2754 bool is_stack_executable;
2755 if (parameters->options().is_execstack_set())
2756 is_stack_executable = parameters->options().is_stack_executable();
2757 else if (!this->input_with_gnu_stack_note_)
2761 if (this->input_requires_executable_stack_)
2762 is_stack_executable = true;
2763 else if (this->input_without_gnu_stack_note_)
2764 is_stack_executable =
2765 parameters->target().is_default_stack_executable();
2767 is_stack_executable = false;
2770 if (parameters->options().relocatable())
2772 const char* name = this->namepool_.add(".note.GNU-stack", false, NULL);
2773 elfcpp::Elf_Xword flags = 0;
2774 if (is_stack_executable)
2775 flags |= elfcpp::SHF_EXECINSTR;
2776 this->make_output_section(name, elfcpp::SHT_PROGBITS, flags,
2777 ORDER_INVALID, false);
2781 if (this->script_options_->saw_phdrs_clause())
2783 int flags = elfcpp::PF_R | elfcpp::PF_W;
2784 if (is_stack_executable)
2785 flags |= elfcpp::PF_X;
2786 this->make_output_segment(elfcpp::PT_GNU_STACK, flags);
2790 // If --build-id was used, set up the build ID note.
2793 Layout::create_build_id()
2795 if (!parameters->options().user_set_build_id())
2798 const char* style = parameters->options().build_id();
2799 if (strcmp(style, "none") == 0)
2802 // Set DESCSZ to the size of the note descriptor. When possible,
2803 // set DESC to the note descriptor contents.
2806 if (strcmp(style, "md5") == 0)
2808 else if (strcmp(style, "sha1") == 0)
2810 else if (strcmp(style, "uuid") == 0)
2812 const size_t uuidsz = 128 / 8;
2814 char buffer[uuidsz];
2815 memset(buffer, 0, uuidsz);
2817 int descriptor = open_descriptor(-1, "/dev/urandom", O_RDONLY);
2819 gold_error(_("--build-id=uuid failed: could not open /dev/urandom: %s"),
2823 ssize_t got = ::read(descriptor, buffer, uuidsz);
2824 release_descriptor(descriptor, true);
2826 gold_error(_("/dev/urandom: read failed: %s"), strerror(errno));
2827 else if (static_cast<size_t>(got) != uuidsz)
2828 gold_error(_("/dev/urandom: expected %zu bytes, got %zd bytes"),
2832 desc.assign(buffer, uuidsz);
2835 else if (strncmp(style, "0x", 2) == 0)
2838 const char* p = style + 2;
2841 if (hex_p(p[0]) && hex_p(p[1]))
2843 char c = (hex_value(p[0]) << 4) | hex_value(p[1]);
2847 else if (*p == '-' || *p == ':')
2850 gold_fatal(_("--build-id argument '%s' not a valid hex number"),
2853 descsz = desc.size();
2856 gold_fatal(_("unrecognized --build-id argument '%s'"), style);
2859 size_t trailing_padding;
2860 Output_section* os = this->create_note("GNU", elfcpp::NT_GNU_BUILD_ID,
2861 ".note.gnu.build-id", descsz, true,
2868 // We know the value already, so we fill it in now.
2869 gold_assert(desc.size() == descsz);
2871 Output_section_data* posd = new Output_data_const(desc, 4);
2872 os->add_output_section_data(posd);
2874 if (trailing_padding != 0)
2876 posd = new Output_data_zero_fill(trailing_padding, 0);
2877 os->add_output_section_data(posd);
2882 // We need to compute a checksum after we have completed the
2884 gold_assert(trailing_padding == 0);
2885 this->build_id_note_ = new Output_data_zero_fill(descsz, 4);
2886 os->add_output_section_data(this->build_id_note_);
2890 // If we have both .stabXX and .stabXXstr sections, then the sh_link
2891 // field of the former should point to the latter. I'm not sure who
2892 // started this, but the GNU linker does it, and some tools depend
2896 Layout::link_stabs_sections()
2898 if (!this->have_stabstr_section_)
2901 for (Section_list::iterator p = this->section_list_.begin();
2902 p != this->section_list_.end();
2905 if ((*p)->type() != elfcpp::SHT_STRTAB)
2908 const char* name = (*p)->name();
2909 if (strncmp(name, ".stab", 5) != 0)
2912 size_t len = strlen(name);
2913 if (strcmp(name + len - 3, "str") != 0)
2916 std::string stab_name(name, len - 3);
2917 Output_section* stab_sec;
2918 stab_sec = this->find_output_section(stab_name.c_str());
2919 if (stab_sec != NULL)
2920 stab_sec->set_link_section(*p);
2924 // Create .gnu_incremental_inputs and related sections needed
2925 // for the next run of incremental linking to check what has changed.
2928 Layout::create_incremental_info_sections(Symbol_table* symtab)
2930 Incremental_inputs* incr = this->incremental_inputs_;
2932 gold_assert(incr != NULL);
2934 // Create the .gnu_incremental_inputs, _symtab, and _relocs input sections.
2935 incr->create_data_sections(symtab);
2937 // Add the .gnu_incremental_inputs section.
2938 const char* incremental_inputs_name =
2939 this->namepool_.add(".gnu_incremental_inputs", false, NULL);
2940 Output_section* incremental_inputs_os =
2941 this->make_output_section(incremental_inputs_name,
2942 elfcpp::SHT_GNU_INCREMENTAL_INPUTS, 0,
2943 ORDER_INVALID, false);
2944 incremental_inputs_os->add_output_section_data(incr->inputs_section());
2946 // Add the .gnu_incremental_symtab section.
2947 const char* incremental_symtab_name =
2948 this->namepool_.add(".gnu_incremental_symtab", false, NULL);
2949 Output_section* incremental_symtab_os =
2950 this->make_output_section(incremental_symtab_name,
2951 elfcpp::SHT_GNU_INCREMENTAL_SYMTAB, 0,
2952 ORDER_INVALID, false);
2953 incremental_symtab_os->add_output_section_data(incr->symtab_section());
2954 incremental_symtab_os->set_entsize(4);
2956 // Add the .gnu_incremental_relocs section.
2957 const char* incremental_relocs_name =
2958 this->namepool_.add(".gnu_incremental_relocs", false, NULL);
2959 Output_section* incremental_relocs_os =
2960 this->make_output_section(incremental_relocs_name,
2961 elfcpp::SHT_GNU_INCREMENTAL_RELOCS, 0,
2962 ORDER_INVALID, false);
2963 incremental_relocs_os->add_output_section_data(incr->relocs_section());
2964 incremental_relocs_os->set_entsize(incr->relocs_entsize());
2966 // Add the .gnu_incremental_got_plt section.
2967 const char* incremental_got_plt_name =
2968 this->namepool_.add(".gnu_incremental_got_plt", false, NULL);
2969 Output_section* incremental_got_plt_os =
2970 this->make_output_section(incremental_got_plt_name,
2971 elfcpp::SHT_GNU_INCREMENTAL_GOT_PLT, 0,
2972 ORDER_INVALID, false);
2973 incremental_got_plt_os->add_output_section_data(incr->got_plt_section());
2975 // Add the .gnu_incremental_strtab section.
2976 const char* incremental_strtab_name =
2977 this->namepool_.add(".gnu_incremental_strtab", false, NULL);
2978 Output_section* incremental_strtab_os = this->make_output_section(incremental_strtab_name,
2979 elfcpp::SHT_STRTAB, 0,
2980 ORDER_INVALID, false);
2981 Output_data_strtab* strtab_data =
2982 new Output_data_strtab(incr->get_stringpool());
2983 incremental_strtab_os->add_output_section_data(strtab_data);
2985 incremental_inputs_os->set_after_input_sections();
2986 incremental_symtab_os->set_after_input_sections();
2987 incremental_relocs_os->set_after_input_sections();
2988 incremental_got_plt_os->set_after_input_sections();
2990 incremental_inputs_os->set_link_section(incremental_strtab_os);
2991 incremental_symtab_os->set_link_section(incremental_inputs_os);
2992 incremental_relocs_os->set_link_section(incremental_inputs_os);
2993 incremental_got_plt_os->set_link_section(incremental_inputs_os);
2996 // Return whether SEG1 should be before SEG2 in the output file. This
2997 // is based entirely on the segment type and flags. When this is
2998 // called the segment addresses have normally not yet been set.
3001 Layout::segment_precedes(const Output_segment* seg1,
3002 const Output_segment* seg2)
3004 elfcpp::Elf_Word type1 = seg1->type();
3005 elfcpp::Elf_Word type2 = seg2->type();
3007 // The single PT_PHDR segment is required to precede any loadable
3008 // segment. We simply make it always first.
3009 if (type1 == elfcpp::PT_PHDR)
3011 gold_assert(type2 != elfcpp::PT_PHDR);
3014 if (type2 == elfcpp::PT_PHDR)
3017 // The single PT_INTERP segment is required to precede any loadable
3018 // segment. We simply make it always second.
3019 if (type1 == elfcpp::PT_INTERP)
3021 gold_assert(type2 != elfcpp::PT_INTERP);
3024 if (type2 == elfcpp::PT_INTERP)
3027 // We then put PT_LOAD segments before any other segments.
3028 if (type1 == elfcpp::PT_LOAD && type2 != elfcpp::PT_LOAD)
3030 if (type2 == elfcpp::PT_LOAD && type1 != elfcpp::PT_LOAD)
3033 // We put the PT_TLS segment last except for the PT_GNU_RELRO
3034 // segment, because that is where the dynamic linker expects to find
3035 // it (this is just for efficiency; other positions would also work
3037 if (type1 == elfcpp::PT_TLS
3038 && type2 != elfcpp::PT_TLS
3039 && type2 != elfcpp::PT_GNU_RELRO)
3041 if (type2 == elfcpp::PT_TLS
3042 && type1 != elfcpp::PT_TLS
3043 && type1 != elfcpp::PT_GNU_RELRO)
3046 // We put the PT_GNU_RELRO segment last, because that is where the
3047 // dynamic linker expects to find it (as with PT_TLS, this is just
3049 if (type1 == elfcpp::PT_GNU_RELRO && type2 != elfcpp::PT_GNU_RELRO)
3051 if (type2 == elfcpp::PT_GNU_RELRO && type1 != elfcpp::PT_GNU_RELRO)
3054 const elfcpp::Elf_Word flags1 = seg1->flags();
3055 const elfcpp::Elf_Word flags2 = seg2->flags();
3057 // The order of non-PT_LOAD segments is unimportant. We simply sort
3058 // by the numeric segment type and flags values. There should not
3059 // be more than one segment with the same type and flags.
3060 if (type1 != elfcpp::PT_LOAD)
3063 return type1 < type2;
3064 gold_assert(flags1 != flags2);
3065 return flags1 < flags2;
3068 // If the addresses are set already, sort by load address.
3069 if (seg1->are_addresses_set())
3071 if (!seg2->are_addresses_set())
3074 unsigned int section_count1 = seg1->output_section_count();
3075 unsigned int section_count2 = seg2->output_section_count();
3076 if (section_count1 == 0 && section_count2 > 0)
3078 if (section_count1 > 0 && section_count2 == 0)
3081 uint64_t paddr1 = (seg1->are_addresses_set()
3083 : seg1->first_section_load_address());
3084 uint64_t paddr2 = (seg2->are_addresses_set()
3086 : seg2->first_section_load_address());
3088 if (paddr1 != paddr2)
3089 return paddr1 < paddr2;
3091 else if (seg2->are_addresses_set())
3094 // A segment which holds large data comes after a segment which does
3095 // not hold large data.
3096 if (seg1->is_large_data_segment())
3098 if (!seg2->is_large_data_segment())
3101 else if (seg2->is_large_data_segment())
3104 // Otherwise, we sort PT_LOAD segments based on the flags. Readonly
3105 // segments come before writable segments. Then writable segments
3106 // with data come before writable segments without data. Then
3107 // executable segments come before non-executable segments. Then
3108 // the unlikely case of a non-readable segment comes before the
3109 // normal case of a readable segment. If there are multiple
3110 // segments with the same type and flags, we require that the
3111 // address be set, and we sort by virtual address and then physical
3113 if ((flags1 & elfcpp::PF_W) != (flags2 & elfcpp::PF_W))
3114 return (flags1 & elfcpp::PF_W) == 0;
3115 if ((flags1 & elfcpp::PF_W) != 0
3116 && seg1->has_any_data_sections() != seg2->has_any_data_sections())
3117 return seg1->has_any_data_sections();
3118 if ((flags1 & elfcpp::PF_X) != (flags2 & elfcpp::PF_X))
3119 return (flags1 & elfcpp::PF_X) != 0;
3120 if ((flags1 & elfcpp::PF_R) != (flags2 & elfcpp::PF_R))
3121 return (flags1 & elfcpp::PF_R) == 0;
3123 // We shouldn't get here--we shouldn't create segments which we
3124 // can't distinguish. Unless of course we are using a weird linker
3125 // script or overlapping --section-start options.
3126 gold_assert(this->script_options_->saw_phdrs_clause()
3127 || parameters->options().any_section_start());
3131 // Increase OFF so that it is congruent to ADDR modulo ABI_PAGESIZE.
3134 align_file_offset(off_t off, uint64_t addr, uint64_t abi_pagesize)
3136 uint64_t unsigned_off = off;
3137 uint64_t aligned_off = ((unsigned_off & ~(abi_pagesize - 1))
3138 | (addr & (abi_pagesize - 1)));
3139 if (aligned_off < unsigned_off)
3140 aligned_off += abi_pagesize;
3144 // Set the file offsets of all the segments, and all the sections they
3145 // contain. They have all been created. LOAD_SEG must be be laid out
3146 // first. Return the offset of the data to follow.
3149 Layout::set_segment_offsets(const Target* target, Output_segment* load_seg,
3150 unsigned int* pshndx)
3152 // Sort them into the final order. We use a stable sort so that we
3153 // don't randomize the order of indistinguishable segments created
3154 // by linker scripts.
3155 std::stable_sort(this->segment_list_.begin(), this->segment_list_.end(),
3156 Layout::Compare_segments(this));
3158 // Find the PT_LOAD segments, and set their addresses and offsets
3159 // and their section's addresses and offsets.
3160 uint64_t start_addr;
3161 if (parameters->options().user_set_Ttext())
3162 start_addr = parameters->options().Ttext();
3163 else if (parameters->options().output_is_position_independent())
3166 start_addr = target->default_text_segment_address();
3168 uint64_t addr = start_addr;
3171 // If LOAD_SEG is NULL, then the file header and segment headers
3172 // will not be loadable. But they still need to be at offset 0 in
3173 // the file. Set their offsets now.
3174 if (load_seg == NULL)
3176 for (Data_list::iterator p = this->special_output_list_.begin();
3177 p != this->special_output_list_.end();
3180 off = align_address(off, (*p)->addralign());
3181 (*p)->set_address_and_file_offset(0, off);
3182 off += (*p)->data_size();
3186 unsigned int increase_relro = this->increase_relro_;
3187 if (this->script_options_->saw_sections_clause())
3190 const bool check_sections = parameters->options().check_sections();
3191 Output_segment* last_load_segment = NULL;
3193 unsigned int shndx_begin = *pshndx;
3194 unsigned int shndx_load_seg = *pshndx;
3196 for (Segment_list::iterator p = this->segment_list_.begin();
3197 p != this->segment_list_.end();
3200 if ((*p)->type() == elfcpp::PT_LOAD)
3202 if (target->isolate_execinstr())
3204 // When we hit the segment that should contain the
3205 // file headers, reset the file offset so we place
3206 // it and subsequent segments appropriately.
3207 // We'll fix up the preceding segments below.
3215 shndx_load_seg = *pshndx;
3221 // Verify that the file headers fall into the first segment.
3222 if (load_seg != NULL && load_seg != *p)
3227 bool are_addresses_set = (*p)->are_addresses_set();
3228 if (are_addresses_set)
3230 // When it comes to setting file offsets, we care about
3231 // the physical address.
3232 addr = (*p)->paddr();
3234 else if (parameters->options().user_set_Ttext()
3235 && ((*p)->flags() & elfcpp::PF_W) == 0)
3237 are_addresses_set = true;
3239 else if (parameters->options().user_set_Tdata()
3240 && ((*p)->flags() & elfcpp::PF_W) != 0
3241 && (!parameters->options().user_set_Tbss()
3242 || (*p)->has_any_data_sections()))
3244 addr = parameters->options().Tdata();
3245 are_addresses_set = true;
3247 else if (parameters->options().user_set_Tbss()
3248 && ((*p)->flags() & elfcpp::PF_W) != 0
3249 && !(*p)->has_any_data_sections())
3251 addr = parameters->options().Tbss();
3252 are_addresses_set = true;
3255 uint64_t orig_addr = addr;
3256 uint64_t orig_off = off;
3258 uint64_t aligned_addr = 0;
3259 uint64_t abi_pagesize = target->abi_pagesize();
3260 uint64_t common_pagesize = target->common_pagesize();
3262 if (!parameters->options().nmagic()
3263 && !parameters->options().omagic())
3264 (*p)->set_minimum_p_align(common_pagesize);
3266 if (!are_addresses_set)
3268 // Skip the address forward one page, maintaining the same
3269 // position within the page. This lets us store both segments
3270 // overlapping on a single page in the file, but the loader will
3271 // put them on different pages in memory. We will revisit this
3272 // decision once we know the size of the segment.
3274 addr = align_address(addr, (*p)->maximum_alignment());
3275 aligned_addr = addr;
3279 // This is the segment that will contain the file
3280 // headers, so its offset will have to be exactly zero.
3281 gold_assert(orig_off == 0);
3283 // If the target wants a fixed minimum distance from the
3284 // text segment to the read-only segment, move up now.
3285 uint64_t min_addr = start_addr + target->rosegment_gap();
3286 if (addr < min_addr)
3289 // But this is not the first segment! To make its
3290 // address congruent with its offset, that address better
3291 // be aligned to the ABI-mandated page size.
3292 addr = align_address(addr, abi_pagesize);
3293 aligned_addr = addr;
3297 if ((addr & (abi_pagesize - 1)) != 0)
3298 addr = addr + abi_pagesize;
3300 off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
3304 if (!parameters->options().nmagic()
3305 && !parameters->options().omagic())
3306 off = align_file_offset(off, addr, abi_pagesize);
3309 // This is -N or -n with a section script which prevents
3310 // us from using a load segment. We need to ensure that
3311 // the file offset is aligned to the alignment of the
3312 // segment. This is because the linker script
3313 // implicitly assumed a zero offset. If we don't align
3314 // here, then the alignment of the sections in the
3315 // linker script may not match the alignment of the
3316 // sections in the set_section_addresses call below,
3317 // causing an error about dot moving backward.
3318 off = align_address(off, (*p)->maximum_alignment());
3321 unsigned int shndx_hold = *pshndx;
3322 bool has_relro = false;
3323 uint64_t new_addr = (*p)->set_section_addresses(this, false, addr,
3328 // Now that we know the size of this segment, we may be able
3329 // to save a page in memory, at the cost of wasting some
3330 // file space, by instead aligning to the start of a new
3331 // page. Here we use the real machine page size rather than
3332 // the ABI mandated page size. If the segment has been
3333 // aligned so that the relro data ends at a page boundary,
3334 // we do not try to realign it.
3336 if (!are_addresses_set
3338 && aligned_addr != addr
3339 && !parameters->incremental())
3341 uint64_t first_off = (common_pagesize
3343 & (common_pagesize - 1)));
3344 uint64_t last_off = new_addr & (common_pagesize - 1);
3347 && ((aligned_addr & ~ (common_pagesize - 1))
3348 != (new_addr & ~ (common_pagesize - 1)))
3349 && first_off + last_off <= common_pagesize)
3351 *pshndx = shndx_hold;
3352 addr = align_address(aligned_addr, common_pagesize);
3353 addr = align_address(addr, (*p)->maximum_alignment());
3354 off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
3355 off = align_file_offset(off, addr, abi_pagesize);
3357 increase_relro = this->increase_relro_;
3358 if (this->script_options_->saw_sections_clause())
3362 new_addr = (*p)->set_section_addresses(this, true, addr,
3371 // Implement --check-sections. We know that the segments
3372 // are sorted by LMA.
3373 if (check_sections && last_load_segment != NULL)
3375 gold_assert(last_load_segment->paddr() <= (*p)->paddr());
3376 if (last_load_segment->paddr() + last_load_segment->memsz()
3379 unsigned long long lb1 = last_load_segment->paddr();
3380 unsigned long long le1 = lb1 + last_load_segment->memsz();
3381 unsigned long long lb2 = (*p)->paddr();
3382 unsigned long long le2 = lb2 + (*p)->memsz();
3383 gold_error(_("load segment overlap [0x%llx -> 0x%llx] and "
3384 "[0x%llx -> 0x%llx]"),
3385 lb1, le1, lb2, le2);
3388 last_load_segment = *p;
3392 if (load_seg != NULL && target->isolate_execinstr())
3394 // Process the early segments again, setting their file offsets
3395 // so they land after the segments starting at LOAD_SEG.
3396 off = align_file_offset(off, 0, target->abi_pagesize());
3398 for (Segment_list::iterator p = this->segment_list_.begin();
3402 if ((*p)->type() == elfcpp::PT_LOAD)
3404 // We repeat the whole job of assigning addresses and
3405 // offsets, but we really only want to change the offsets and
3406 // must ensure that the addresses all come out the same as
3407 // they did the first time through.
3408 bool has_relro = false;
3409 const uint64_t old_addr = (*p)->vaddr();
3410 const uint64_t old_end = old_addr + (*p)->memsz();
3411 uint64_t new_addr = (*p)->set_section_addresses(this, true,
3417 gold_assert(new_addr == old_end);
3421 gold_assert(shndx_begin == shndx_load_seg);
3424 // Handle the non-PT_LOAD segments, setting their offsets from their
3425 // section's offsets.
3426 for (Segment_list::iterator p = this->segment_list_.begin();
3427 p != this->segment_list_.end();
3430 if ((*p)->type() != elfcpp::PT_LOAD)
3431 (*p)->set_offset((*p)->type() == elfcpp::PT_GNU_RELRO
3436 // Set the TLS offsets for each section in the PT_TLS segment.
3437 if (this->tls_segment_ != NULL)
3438 this->tls_segment_->set_tls_offsets();
3443 // Set the offsets of all the allocated sections when doing a
3444 // relocatable link. This does the same jobs as set_segment_offsets,
3445 // only for a relocatable link.
3448 Layout::set_relocatable_section_offsets(Output_data* file_header,
3449 unsigned int* pshndx)
3453 file_header->set_address_and_file_offset(0, 0);
3454 off += file_header->data_size();
3456 for (Section_list::iterator p = this->section_list_.begin();
3457 p != this->section_list_.end();
3460 // We skip unallocated sections here, except that group sections
3461 // have to come first.
3462 if (((*p)->flags() & elfcpp::SHF_ALLOC) == 0
3463 && (*p)->type() != elfcpp::SHT_GROUP)
3466 off = align_address(off, (*p)->addralign());
3468 // The linker script might have set the address.
3469 if (!(*p)->is_address_valid())
3470 (*p)->set_address(0);
3471 (*p)->set_file_offset(off);
3472 (*p)->finalize_data_size();
3473 off += (*p)->data_size();
3475 (*p)->set_out_shndx(*pshndx);
3482 // Set the file offset of all the sections not associated with a
3486 Layout::set_section_offsets(off_t off, Layout::Section_offset_pass pass)
3488 off_t startoff = off;
3491 for (Section_list::iterator p = this->unattached_section_list_.begin();
3492 p != this->unattached_section_list_.end();
3495 // The symtab section is handled in create_symtab_sections.
3496 if (*p == this->symtab_section_)
3499 // If we've already set the data size, don't set it again.
3500 if ((*p)->is_offset_valid() && (*p)->is_data_size_valid())
3503 if (pass == BEFORE_INPUT_SECTIONS_PASS
3504 && (*p)->requires_postprocessing())
3506 (*p)->create_postprocessing_buffer();
3507 this->any_postprocessing_sections_ = true;
3510 if (pass == BEFORE_INPUT_SECTIONS_PASS
3511 && (*p)->after_input_sections())
3513 else if (pass == POSTPROCESSING_SECTIONS_PASS
3514 && (!(*p)->after_input_sections()
3515 || (*p)->type() == elfcpp::SHT_STRTAB))
3517 else if (pass == STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
3518 && (!(*p)->after_input_sections()
3519 || (*p)->type() != elfcpp::SHT_STRTAB))
3522 if (!parameters->incremental_update())
3524 off = align_address(off, (*p)->addralign());
3525 (*p)->set_file_offset(off);
3526 (*p)->finalize_data_size();
3530 // Incremental update: allocate file space from free list.
3531 (*p)->pre_finalize_data_size();
3532 off_t current_size = (*p)->current_data_size();
3533 off = this->allocate(current_size, (*p)->addralign(), startoff);
3536 if (is_debugging_enabled(DEBUG_INCREMENTAL))
3537 this->free_list_.dump();
3538 gold_assert((*p)->output_section() != NULL);
3539 gold_fallback(_("out of patch space for section %s; "
3540 "relink with --incremental-full"),
3541 (*p)->output_section()->name());
3543 (*p)->set_file_offset(off);
3544 (*p)->finalize_data_size();
3545 if ((*p)->data_size() > current_size)
3547 gold_assert((*p)->output_section() != NULL);
3548 gold_fallback(_("%s: section changed size; "
3549 "relink with --incremental-full"),
3550 (*p)->output_section()->name());
3552 gold_debug(DEBUG_INCREMENTAL,
3553 "set_section_offsets: %08lx %08lx %s",
3554 static_cast<long>(off),
3555 static_cast<long>((*p)->data_size()),
3556 ((*p)->output_section() != NULL
3557 ? (*p)->output_section()->name() : "(special)"));
3560 off += (*p)->data_size();
3564 // At this point the name must be set.
3565 if (pass != STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS)
3566 this->namepool_.add((*p)->name(), false, NULL);
3571 // Set the section indexes of all the sections not associated with a
3575 Layout::set_section_indexes(unsigned int shndx)
3577 for (Section_list::iterator p = this->unattached_section_list_.begin();
3578 p != this->unattached_section_list_.end();
3581 if (!(*p)->has_out_shndx())
3583 (*p)->set_out_shndx(shndx);
3590 // Set the section addresses according to the linker script. This is
3591 // only called when we see a SECTIONS clause. This returns the
3592 // program segment which should hold the file header and segment
3593 // headers, if any. It will return NULL if they should not be in a
3597 Layout::set_section_addresses_from_script(Symbol_table* symtab)
3599 Script_sections* ss = this->script_options_->script_sections();
3600 gold_assert(ss->saw_sections_clause());
3601 return this->script_options_->set_section_addresses(symtab, this);
3604 // Place the orphan sections in the linker script.
3607 Layout::place_orphan_sections_in_script()
3609 Script_sections* ss = this->script_options_->script_sections();
3610 gold_assert(ss->saw_sections_clause());
3612 // Place each orphaned output section in the script.
3613 for (Section_list::iterator p = this->section_list_.begin();
3614 p != this->section_list_.end();
3617 if (!(*p)->found_in_sections_clause())
3618 ss->place_orphan(*p);
3622 // Count the local symbols in the regular symbol table and the dynamic
3623 // symbol table, and build the respective string pools.
3626 Layout::count_local_symbols(const Task* task,
3627 const Input_objects* input_objects)
3629 // First, figure out an upper bound on the number of symbols we'll
3630 // be inserting into each pool. This helps us create the pools with
3631 // the right size, to avoid unnecessary hashtable resizing.
3632 unsigned int symbol_count = 0;
3633 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
3634 p != input_objects->relobj_end();
3636 symbol_count += (*p)->local_symbol_count();
3638 // Go from "upper bound" to "estimate." We overcount for two
3639 // reasons: we double-count symbols that occur in more than one
3640 // object file, and we count symbols that are dropped from the
3641 // output. Add it all together and assume we overcount by 100%.
3644 // We assume all symbols will go into both the sympool and dynpool.
3645 this->sympool_.reserve(symbol_count);
3646 this->dynpool_.reserve(symbol_count);
3648 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
3649 p != input_objects->relobj_end();
3652 Task_lock_obj<Object> tlo(task, *p);
3653 (*p)->count_local_symbols(&this->sympool_, &this->dynpool_);
3657 // Create the symbol table sections. Here we also set the final
3658 // values of the symbols. At this point all the loadable sections are
3659 // fully laid out. SHNUM is the number of sections so far.
3662 Layout::create_symtab_sections(const Input_objects* input_objects,
3663 Symbol_table* symtab,
3669 if (parameters->target().get_size() == 32)
3671 symsize = elfcpp::Elf_sizes<32>::sym_size;
3674 else if (parameters->target().get_size() == 64)
3676 symsize = elfcpp::Elf_sizes<64>::sym_size;
3682 // Compute file offsets relative to the start of the symtab section.
3685 // Save space for the dummy symbol at the start of the section. We
3686 // never bother to write this out--it will just be left as zero.
3688 unsigned int local_symbol_index = 1;
3690 // Add STT_SECTION symbols for each Output section which needs one.
3691 for (Section_list::iterator p = this->section_list_.begin();
3692 p != this->section_list_.end();
3695 if (!(*p)->needs_symtab_index())
3696 (*p)->set_symtab_index(-1U);
3699 (*p)->set_symtab_index(local_symbol_index);
3700 ++local_symbol_index;
3705 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
3706 p != input_objects->relobj_end();
3709 unsigned int index = (*p)->finalize_local_symbols(local_symbol_index,
3711 off += (index - local_symbol_index) * symsize;
3712 local_symbol_index = index;
3715 unsigned int local_symcount = local_symbol_index;
3716 gold_assert(static_cast<off_t>(local_symcount * symsize) == off);
3719 size_t dyn_global_index;
3721 if (this->dynsym_section_ == NULL)
3724 dyn_global_index = 0;
3729 dyn_global_index = this->dynsym_section_->info();
3730 off_t locsize = dyn_global_index * this->dynsym_section_->entsize();
3731 dynoff = this->dynsym_section_->offset() + locsize;
3732 dyncount = (this->dynsym_section_->data_size() - locsize) / symsize;
3733 gold_assert(static_cast<off_t>(dyncount * symsize)
3734 == this->dynsym_section_->data_size() - locsize);
3737 off_t global_off = off;
3738 off = symtab->finalize(off, dynoff, dyn_global_index, dyncount,
3739 &this->sympool_, &local_symcount);
3741 if (!parameters->options().strip_all())
3743 this->sympool_.set_string_offsets();
3745 const char* symtab_name = this->namepool_.add(".symtab", false, NULL);
3746 Output_section* osymtab = this->make_output_section(symtab_name,
3750 this->symtab_section_ = osymtab;
3752 Output_section_data* pos = new Output_data_fixed_space(off, align,
3754 osymtab->add_output_section_data(pos);
3756 // We generate a .symtab_shndx section if we have more than
3757 // SHN_LORESERVE sections. Technically it is possible that we
3758 // don't need one, because it is possible that there are no
3759 // symbols in any of sections with indexes larger than
3760 // SHN_LORESERVE. That is probably unusual, though, and it is
3761 // easier to always create one than to compute section indexes
3762 // twice (once here, once when writing out the symbols).
3763 if (shnum >= elfcpp::SHN_LORESERVE)
3765 const char* symtab_xindex_name = this->namepool_.add(".symtab_shndx",
3767 Output_section* osymtab_xindex =
3768 this->make_output_section(symtab_xindex_name,
3769 elfcpp::SHT_SYMTAB_SHNDX, 0,
3770 ORDER_INVALID, false);
3772 size_t symcount = off / symsize;
3773 this->symtab_xindex_ = new Output_symtab_xindex(symcount);
3775 osymtab_xindex->add_output_section_data(this->symtab_xindex_);
3777 osymtab_xindex->set_link_section(osymtab);
3778 osymtab_xindex->set_addralign(4);
3779 osymtab_xindex->set_entsize(4);
3781 osymtab_xindex->set_after_input_sections();
3783 // This tells the driver code to wait until the symbol table
3784 // has written out before writing out the postprocessing
3785 // sections, including the .symtab_shndx section.
3786 this->any_postprocessing_sections_ = true;
3789 const char* strtab_name = this->namepool_.add(".strtab", false, NULL);
3790 Output_section* ostrtab = this->make_output_section(strtab_name,
3795 Output_section_data* pstr = new Output_data_strtab(&this->sympool_);
3796 ostrtab->add_output_section_data(pstr);
3799 if (!parameters->incremental_update())
3800 symtab_off = align_address(*poff, align);
3803 symtab_off = this->allocate(off, align, *poff);
3805 gold_fallback(_("out of patch space for symbol table; "
3806 "relink with --incremental-full"));
3807 gold_debug(DEBUG_INCREMENTAL,
3808 "create_symtab_sections: %08lx %08lx .symtab",
3809 static_cast<long>(symtab_off),
3810 static_cast<long>(off));
3813 symtab->set_file_offset(symtab_off + global_off);
3814 osymtab->set_file_offset(symtab_off);
3815 osymtab->finalize_data_size();
3816 osymtab->set_link_section(ostrtab);
3817 osymtab->set_info(local_symcount);
3818 osymtab->set_entsize(symsize);
3820 if (symtab_off + off > *poff)
3821 *poff = symtab_off + off;
3825 // Create the .shstrtab section, which holds the names of the
3826 // sections. At the time this is called, we have created all the
3827 // output sections except .shstrtab itself.
3830 Layout::create_shstrtab()
3832 // FIXME: We don't need to create a .shstrtab section if we are
3833 // stripping everything.
3835 const char* name = this->namepool_.add(".shstrtab", false, NULL);
3837 Output_section* os = this->make_output_section(name, elfcpp::SHT_STRTAB, 0,
3838 ORDER_INVALID, false);
3840 if (strcmp(parameters->options().compress_debug_sections(), "none") != 0)
3842 // We can't write out this section until we've set all the
3843 // section names, and we don't set the names of compressed
3844 // output sections until relocations are complete. FIXME: With
3845 // the current names we use, this is unnecessary.
3846 os->set_after_input_sections();
3849 Output_section_data* posd = new Output_data_strtab(&this->namepool_);
3850 os->add_output_section_data(posd);
3855 // Create the section headers. SIZE is 32 or 64. OFF is the file
3859 Layout::create_shdrs(const Output_section* shstrtab_section, off_t* poff)
3861 Output_section_headers* oshdrs;
3862 oshdrs = new Output_section_headers(this,
3863 &this->segment_list_,
3864 &this->section_list_,
3865 &this->unattached_section_list_,
3869 if (!parameters->incremental_update())
3870 off = align_address(*poff, oshdrs->addralign());
3873 oshdrs->pre_finalize_data_size();
3874 off = this->allocate(oshdrs->data_size(), oshdrs->addralign(), *poff);
3876 gold_fallback(_("out of patch space for section header table; "
3877 "relink with --incremental-full"));
3878 gold_debug(DEBUG_INCREMENTAL,
3879 "create_shdrs: %08lx %08lx (section header table)",
3880 static_cast<long>(off),
3881 static_cast<long>(off + oshdrs->data_size()));
3883 oshdrs->set_address_and_file_offset(0, off);
3884 off += oshdrs->data_size();
3887 this->section_headers_ = oshdrs;
3890 // Count the allocated sections.
3893 Layout::allocated_output_section_count() const
3895 size_t section_count = 0;
3896 for (Segment_list::const_iterator p = this->segment_list_.begin();
3897 p != this->segment_list_.end();
3899 section_count += (*p)->output_section_count();
3900 return section_count;
3903 // Create the dynamic symbol table.
3906 Layout::create_dynamic_symtab(const Input_objects* input_objects,
3907 Symbol_table* symtab,
3908 Output_section** pdynstr,
3909 unsigned int* plocal_dynamic_count,
3910 std::vector<Symbol*>* pdynamic_symbols,
3911 Versions* pversions)
3913 // Count all the symbols in the dynamic symbol table, and set the
3914 // dynamic symbol indexes.
3916 // Skip symbol 0, which is always all zeroes.
3917 unsigned int index = 1;
3919 // Add STT_SECTION symbols for each Output section which needs one.
3920 for (Section_list::iterator p = this->section_list_.begin();
3921 p != this->section_list_.end();
3924 if (!(*p)->needs_dynsym_index())
3925 (*p)->set_dynsym_index(-1U);
3928 (*p)->set_dynsym_index(index);
3933 // Count the local symbols that need to go in the dynamic symbol table,
3934 // and set the dynamic symbol indexes.
3935 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
3936 p != input_objects->relobj_end();
3939 unsigned int new_index = (*p)->set_local_dynsym_indexes(index);
3943 unsigned int local_symcount = index;
3944 *plocal_dynamic_count = local_symcount;
3946 index = symtab->set_dynsym_indexes(index, pdynamic_symbols,
3947 &this->dynpool_, pversions);
3951 const int size = parameters->target().get_size();
3954 symsize = elfcpp::Elf_sizes<32>::sym_size;
3957 else if (size == 64)
3959 symsize = elfcpp::Elf_sizes<64>::sym_size;
3965 // Create the dynamic symbol table section.
3967 Output_section* dynsym = this->choose_output_section(NULL, ".dynsym",
3971 ORDER_DYNAMIC_LINKER,
3974 // Check for NULL as a linker script may discard .dynsym.
3977 Output_section_data* odata = new Output_data_fixed_space(index * symsize,
3980 dynsym->add_output_section_data(odata);
3982 dynsym->set_info(local_symcount);
3983 dynsym->set_entsize(symsize);
3984 dynsym->set_addralign(align);
3986 this->dynsym_section_ = dynsym;
3989 Output_data_dynamic* const odyn = this->dynamic_data_;
3992 odyn->add_section_address(elfcpp::DT_SYMTAB, dynsym);
3993 odyn->add_constant(elfcpp::DT_SYMENT, symsize);
3996 // If there are more than SHN_LORESERVE allocated sections, we
3997 // create a .dynsym_shndx section. It is possible that we don't
3998 // need one, because it is possible that there are no dynamic
3999 // symbols in any of the sections with indexes larger than
4000 // SHN_LORESERVE. This is probably unusual, though, and at this
4001 // time we don't know the actual section indexes so it is
4002 // inconvenient to check.
4003 if (this->allocated_output_section_count() >= elfcpp::SHN_LORESERVE)
4005 Output_section* dynsym_xindex =
4006 this->choose_output_section(NULL, ".dynsym_shndx",
4007 elfcpp::SHT_SYMTAB_SHNDX,
4009 false, ORDER_DYNAMIC_LINKER, false);
4011 if (dynsym_xindex != NULL)
4013 this->dynsym_xindex_ = new Output_symtab_xindex(index);
4015 dynsym_xindex->add_output_section_data(this->dynsym_xindex_);
4017 dynsym_xindex->set_link_section(dynsym);
4018 dynsym_xindex->set_addralign(4);
4019 dynsym_xindex->set_entsize(4);
4021 dynsym_xindex->set_after_input_sections();
4023 // This tells the driver code to wait until the symbol table
4024 // has written out before writing out the postprocessing
4025 // sections, including the .dynsym_shndx section.
4026 this->any_postprocessing_sections_ = true;
4030 // Create the dynamic string table section.
4032 Output_section* dynstr = this->choose_output_section(NULL, ".dynstr",
4036 ORDER_DYNAMIC_LINKER,
4041 Output_section_data* strdata = new Output_data_strtab(&this->dynpool_);
4042 dynstr->add_output_section_data(strdata);
4045 dynsym->set_link_section(dynstr);
4046 if (this->dynamic_section_ != NULL)
4047 this->dynamic_section_->set_link_section(dynstr);
4051 odyn->add_section_address(elfcpp::DT_STRTAB, dynstr);
4052 odyn->add_section_size(elfcpp::DT_STRSZ, dynstr);
4058 // Create the hash tables.
4060 if (strcmp(parameters->options().hash_style(), "sysv") == 0
4061 || strcmp(parameters->options().hash_style(), "both") == 0)
4063 unsigned char* phash;
4064 unsigned int hashlen;
4065 Dynobj::create_elf_hash_table(*pdynamic_symbols, local_symcount,
4068 Output_section* hashsec =
4069 this->choose_output_section(NULL, ".hash", elfcpp::SHT_HASH,
4070 elfcpp::SHF_ALLOC, false,
4071 ORDER_DYNAMIC_LINKER, false);
4073 Output_section_data* hashdata = new Output_data_const_buffer(phash,
4077 if (hashsec != NULL && hashdata != NULL)
4078 hashsec->add_output_section_data(hashdata);
4080 if (hashsec != NULL)
4083 hashsec->set_link_section(dynsym);
4084 hashsec->set_entsize(4);
4088 odyn->add_section_address(elfcpp::DT_HASH, hashsec);
4091 if (strcmp(parameters->options().hash_style(), "gnu") == 0
4092 || strcmp(parameters->options().hash_style(), "both") == 0)
4094 unsigned char* phash;
4095 unsigned int hashlen;
4096 Dynobj::create_gnu_hash_table(*pdynamic_symbols, local_symcount,
4099 Output_section* hashsec =
4100 this->choose_output_section(NULL, ".gnu.hash", elfcpp::SHT_GNU_HASH,
4101 elfcpp::SHF_ALLOC, false,
4102 ORDER_DYNAMIC_LINKER, false);
4104 Output_section_data* hashdata = new Output_data_const_buffer(phash,
4108 if (hashsec != NULL && hashdata != NULL)
4109 hashsec->add_output_section_data(hashdata);
4111 if (hashsec != NULL)
4114 hashsec->set_link_section(dynsym);
4116 // For a 64-bit target, the entries in .gnu.hash do not have
4117 // a uniform size, so we only set the entry size for a
4119 if (parameters->target().get_size() == 32)
4120 hashsec->set_entsize(4);
4123 odyn->add_section_address(elfcpp::DT_GNU_HASH, hashsec);
4128 // Assign offsets to each local portion of the dynamic symbol table.
4131 Layout::assign_local_dynsym_offsets(const Input_objects* input_objects)
4133 Output_section* dynsym = this->dynsym_section_;
4137 off_t off = dynsym->offset();
4139 // Skip the dummy symbol at the start of the section.
4140 off += dynsym->entsize();
4142 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
4143 p != input_objects->relobj_end();
4146 unsigned int count = (*p)->set_local_dynsym_offset(off);
4147 off += count * dynsym->entsize();
4151 // Create the version sections.
4154 Layout::create_version_sections(const Versions* versions,
4155 const Symbol_table* symtab,
4156 unsigned int local_symcount,
4157 const std::vector<Symbol*>& dynamic_symbols,
4158 const Output_section* dynstr)
4160 if (!versions->any_defs() && !versions->any_needs())
4163 switch (parameters->size_and_endianness())
4165 #ifdef HAVE_TARGET_32_LITTLE
4166 case Parameters::TARGET_32_LITTLE:
4167 this->sized_create_version_sections<32, false>(versions, symtab,
4169 dynamic_symbols, dynstr);
4172 #ifdef HAVE_TARGET_32_BIG
4173 case Parameters::TARGET_32_BIG:
4174 this->sized_create_version_sections<32, true>(versions, symtab,
4176 dynamic_symbols, dynstr);
4179 #ifdef HAVE_TARGET_64_LITTLE
4180 case Parameters::TARGET_64_LITTLE:
4181 this->sized_create_version_sections<64, false>(versions, symtab,
4183 dynamic_symbols, dynstr);
4186 #ifdef HAVE_TARGET_64_BIG
4187 case Parameters::TARGET_64_BIG:
4188 this->sized_create_version_sections<64, true>(versions, symtab,
4190 dynamic_symbols, dynstr);
4198 // Create the version sections, sized version.
4200 template<int size, bool big_endian>
4202 Layout::sized_create_version_sections(
4203 const Versions* versions,
4204 const Symbol_table* symtab,
4205 unsigned int local_symcount,
4206 const std::vector<Symbol*>& dynamic_symbols,
4207 const Output_section* dynstr)
4209 Output_section* vsec = this->choose_output_section(NULL, ".gnu.version",
4210 elfcpp::SHT_GNU_versym,
4213 ORDER_DYNAMIC_LINKER,
4216 // Check for NULL since a linker script may discard this section.
4219 unsigned char* vbuf;
4221 versions->symbol_section_contents<size, big_endian>(symtab,
4227 Output_section_data* vdata = new Output_data_const_buffer(vbuf, vsize, 2,
4230 vsec->add_output_section_data(vdata);
4231 vsec->set_entsize(2);
4232 vsec->set_link_section(this->dynsym_section_);
4235 Output_data_dynamic* const odyn = this->dynamic_data_;
4236 if (odyn != NULL && vsec != NULL)
4237 odyn->add_section_address(elfcpp::DT_VERSYM, vsec);
4239 if (versions->any_defs())
4241 Output_section* vdsec;
4242 vdsec = this->choose_output_section(NULL, ".gnu.version_d",
4243 elfcpp::SHT_GNU_verdef,
4245 false, ORDER_DYNAMIC_LINKER, false);
4249 unsigned char* vdbuf;
4250 unsigned int vdsize;
4251 unsigned int vdentries;
4252 versions->def_section_contents<size, big_endian>(&this->dynpool_,
4256 Output_section_data* vddata =
4257 new Output_data_const_buffer(vdbuf, vdsize, 4, "** version defs");
4259 vdsec->add_output_section_data(vddata);
4260 vdsec->set_link_section(dynstr);
4261 vdsec->set_info(vdentries);
4265 odyn->add_section_address(elfcpp::DT_VERDEF, vdsec);
4266 odyn->add_constant(elfcpp::DT_VERDEFNUM, vdentries);
4271 if (versions->any_needs())
4273 Output_section* vnsec;
4274 vnsec = this->choose_output_section(NULL, ".gnu.version_r",
4275 elfcpp::SHT_GNU_verneed,
4277 false, ORDER_DYNAMIC_LINKER, false);
4281 unsigned char* vnbuf;
4282 unsigned int vnsize;
4283 unsigned int vnentries;
4284 versions->need_section_contents<size, big_endian>(&this->dynpool_,
4288 Output_section_data* vndata =
4289 new Output_data_const_buffer(vnbuf, vnsize, 4, "** version refs");
4291 vnsec->add_output_section_data(vndata);
4292 vnsec->set_link_section(dynstr);
4293 vnsec->set_info(vnentries);
4297 odyn->add_section_address(elfcpp::DT_VERNEED, vnsec);
4298 odyn->add_constant(elfcpp::DT_VERNEEDNUM, vnentries);
4304 // Create the .interp section and PT_INTERP segment.
4307 Layout::create_interp(const Target* target)
4309 gold_assert(this->interp_segment_ == NULL);
4311 const char* interp = parameters->options().dynamic_linker();
4314 interp = target->dynamic_linker();
4315 gold_assert(interp != NULL);
4318 size_t len = strlen(interp) + 1;
4320 Output_section_data* odata = new Output_data_const(interp, len, 1);
4322 Output_section* osec = this->choose_output_section(NULL, ".interp",
4323 elfcpp::SHT_PROGBITS,
4325 false, ORDER_INTERP,
4328 osec->add_output_section_data(odata);
4331 // Add dynamic tags for the PLT and the dynamic relocs. This is
4332 // called by the target-specific code. This does nothing if not doing
4335 // USE_REL is true for REL relocs rather than RELA relocs.
4337 // If PLT_GOT is not NULL, then DT_PLTGOT points to it.
4339 // If PLT_REL is not NULL, it is used for DT_PLTRELSZ, and DT_JMPREL,
4340 // and we also set DT_PLTREL. We use PLT_REL's output section, since
4341 // some targets have multiple reloc sections in PLT_REL.
4343 // If DYN_REL is not NULL, it is used for DT_REL/DT_RELA,
4344 // DT_RELSZ/DT_RELASZ, DT_RELENT/DT_RELAENT. Again we use the output
4347 // If ADD_DEBUG is true, we add a DT_DEBUG entry when generating an
4351 Layout::add_target_dynamic_tags(bool use_rel, const Output_data* plt_got,
4352 const Output_data* plt_rel,
4353 const Output_data_reloc_generic* dyn_rel,
4354 bool add_debug, bool dynrel_includes_plt)
4356 Output_data_dynamic* odyn = this->dynamic_data_;
4360 if (plt_got != NULL && plt_got->output_section() != NULL)
4361 odyn->add_section_address(elfcpp::DT_PLTGOT, plt_got);
4363 if (plt_rel != NULL && plt_rel->output_section() != NULL)
4365 odyn->add_section_size(elfcpp::DT_PLTRELSZ, plt_rel->output_section());
4366 odyn->add_section_address(elfcpp::DT_JMPREL, plt_rel->output_section());
4367 odyn->add_constant(elfcpp::DT_PLTREL,
4368 use_rel ? elfcpp::DT_REL : elfcpp::DT_RELA);
4371 if ((dyn_rel != NULL && dyn_rel->output_section() != NULL)
4372 || (dynrel_includes_plt
4374 && plt_rel->output_section() != NULL))
4376 bool have_dyn_rel = dyn_rel != NULL && dyn_rel->output_section() != NULL;
4377 bool have_plt_rel = plt_rel != NULL && plt_rel->output_section() != NULL;
4378 odyn->add_section_address(use_rel ? elfcpp::DT_REL : elfcpp::DT_RELA,
4380 ? dyn_rel->output_section()
4381 : plt_rel->output_section()));
4382 elfcpp::DT size_tag = use_rel ? elfcpp::DT_RELSZ : elfcpp::DT_RELASZ;
4383 if (have_dyn_rel && have_plt_rel && dynrel_includes_plt)
4384 odyn->add_section_size(size_tag,
4385 dyn_rel->output_section(),
4386 plt_rel->output_section());
4387 else if (have_dyn_rel)
4388 odyn->add_section_size(size_tag, dyn_rel->output_section());
4390 odyn->add_section_size(size_tag, plt_rel->output_section());
4391 const int size = parameters->target().get_size();
4396 rel_tag = elfcpp::DT_RELENT;
4398 rel_size = Reloc_types<elfcpp::SHT_REL, 32, false>::reloc_size;
4399 else if (size == 64)
4400 rel_size = Reloc_types<elfcpp::SHT_REL, 64, false>::reloc_size;
4406 rel_tag = elfcpp::DT_RELAENT;
4408 rel_size = Reloc_types<elfcpp::SHT_RELA, 32, false>::reloc_size;
4409 else if (size == 64)
4410 rel_size = Reloc_types<elfcpp::SHT_RELA, 64, false>::reloc_size;
4414 odyn->add_constant(rel_tag, rel_size);
4416 if (parameters->options().combreloc() && have_dyn_rel)
4418 size_t c = dyn_rel->relative_reloc_count();
4420 odyn->add_constant((use_rel
4421 ? elfcpp::DT_RELCOUNT
4422 : elfcpp::DT_RELACOUNT),
4427 if (add_debug && !parameters->options().shared())
4429 // The value of the DT_DEBUG tag is filled in by the dynamic
4430 // linker at run time, and used by the debugger.
4431 odyn->add_constant(elfcpp::DT_DEBUG, 0);
4435 // Finish the .dynamic section and PT_DYNAMIC segment.
4438 Layout::finish_dynamic_section(const Input_objects* input_objects,
4439 const Symbol_table* symtab)
4441 if (!this->script_options_->saw_phdrs_clause()
4442 && this->dynamic_section_ != NULL)
4444 Output_segment* oseg = this->make_output_segment(elfcpp::PT_DYNAMIC,
4447 oseg->add_output_section_to_nonload(this->dynamic_section_,
4448 elfcpp::PF_R | elfcpp::PF_W);
4451 Output_data_dynamic* const odyn = this->dynamic_data_;
4455 for (Input_objects::Dynobj_iterator p = input_objects->dynobj_begin();
4456 p != input_objects->dynobj_end();
4459 if (!(*p)->is_needed() && (*p)->as_needed())
4461 // This dynamic object was linked with --as-needed, but it
4466 odyn->add_string(elfcpp::DT_NEEDED, (*p)->soname());
4469 if (parameters->options().shared())
4471 const char* soname = parameters->options().soname();
4473 odyn->add_string(elfcpp::DT_SONAME, soname);
4476 Symbol* sym = symtab->lookup(parameters->options().init());
4477 if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj())
4478 odyn->add_symbol(elfcpp::DT_INIT, sym);
4480 sym = symtab->lookup(parameters->options().fini());
4481 if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj())
4482 odyn->add_symbol(elfcpp::DT_FINI, sym);
4484 // Look for .init_array, .preinit_array and .fini_array by checking
4486 for(Layout::Section_list::const_iterator p = this->section_list_.begin();
4487 p != this->section_list_.end();
4489 switch((*p)->type())
4491 case elfcpp::SHT_FINI_ARRAY:
4492 odyn->add_section_address(elfcpp::DT_FINI_ARRAY, *p);
4493 odyn->add_section_size(elfcpp::DT_FINI_ARRAYSZ, *p);
4495 case elfcpp::SHT_INIT_ARRAY:
4496 odyn->add_section_address(elfcpp::DT_INIT_ARRAY, *p);
4497 odyn->add_section_size(elfcpp::DT_INIT_ARRAYSZ, *p);
4499 case elfcpp::SHT_PREINIT_ARRAY:
4500 odyn->add_section_address(elfcpp::DT_PREINIT_ARRAY, *p);
4501 odyn->add_section_size(elfcpp::DT_PREINIT_ARRAYSZ, *p);
4507 // Add a DT_RPATH entry if needed.
4508 const General_options::Dir_list& rpath(parameters->options().rpath());
4511 std::string rpath_val;
4512 for (General_options::Dir_list::const_iterator p = rpath.begin();
4516 if (rpath_val.empty())
4517 rpath_val = p->name();
4520 // Eliminate duplicates.
4521 General_options::Dir_list::const_iterator q;
4522 for (q = rpath.begin(); q != p; ++q)
4523 if (q->name() == p->name())
4528 rpath_val += p->name();
4533 odyn->add_string(elfcpp::DT_RPATH, rpath_val);
4534 if (parameters->options().enable_new_dtags())
4535 odyn->add_string(elfcpp::DT_RUNPATH, rpath_val);
4538 // Look for text segments that have dynamic relocations.
4539 bool have_textrel = false;
4540 if (!this->script_options_->saw_sections_clause())
4542 for (Segment_list::const_iterator p = this->segment_list_.begin();
4543 p != this->segment_list_.end();
4546 if ((*p)->type() == elfcpp::PT_LOAD
4547 && ((*p)->flags() & elfcpp::PF_W) == 0
4548 && (*p)->has_dynamic_reloc())
4550 have_textrel = true;
4557 // We don't know the section -> segment mapping, so we are
4558 // conservative and just look for readonly sections with
4559 // relocations. If those sections wind up in writable segments,
4560 // then we have created an unnecessary DT_TEXTREL entry.
4561 for (Section_list::const_iterator p = this->section_list_.begin();
4562 p != this->section_list_.end();
4565 if (((*p)->flags() & elfcpp::SHF_ALLOC) != 0
4566 && ((*p)->flags() & elfcpp::SHF_WRITE) == 0
4567 && (*p)->has_dynamic_reloc())
4569 have_textrel = true;
4575 if (parameters->options().filter() != NULL)
4576 odyn->add_string(elfcpp::DT_FILTER, parameters->options().filter());
4577 if (parameters->options().any_auxiliary())
4579 for (options::String_set::const_iterator p =
4580 parameters->options().auxiliary_begin();
4581 p != parameters->options().auxiliary_end();
4583 odyn->add_string(elfcpp::DT_AUXILIARY, *p);
4586 // Add a DT_FLAGS entry if necessary.
4587 unsigned int flags = 0;
4590 // Add a DT_TEXTREL for compatibility with older loaders.
4591 odyn->add_constant(elfcpp::DT_TEXTREL, 0);
4592 flags |= elfcpp::DF_TEXTREL;
4594 if (parameters->options().text())
4595 gold_error(_("read-only segment has dynamic relocations"));
4596 else if (parameters->options().warn_shared_textrel()
4597 && parameters->options().shared())
4598 gold_warning(_("shared library text segment is not shareable"));
4600 if (parameters->options().shared() && this->has_static_tls())
4601 flags |= elfcpp::DF_STATIC_TLS;
4602 if (parameters->options().origin())
4603 flags |= elfcpp::DF_ORIGIN;
4604 if (parameters->options().Bsymbolic())
4606 flags |= elfcpp::DF_SYMBOLIC;
4607 // Add DT_SYMBOLIC for compatibility with older loaders.
4608 odyn->add_constant(elfcpp::DT_SYMBOLIC, 0);
4610 if (parameters->options().now())
4611 flags |= elfcpp::DF_BIND_NOW;
4613 odyn->add_constant(elfcpp::DT_FLAGS, flags);
4616 if (parameters->options().initfirst())
4617 flags |= elfcpp::DF_1_INITFIRST;
4618 if (parameters->options().interpose())
4619 flags |= elfcpp::DF_1_INTERPOSE;
4620 if (parameters->options().loadfltr())
4621 flags |= elfcpp::DF_1_LOADFLTR;
4622 if (parameters->options().nodefaultlib())
4623 flags |= elfcpp::DF_1_NODEFLIB;
4624 if (parameters->options().nodelete())
4625 flags |= elfcpp::DF_1_NODELETE;
4626 if (parameters->options().nodlopen())
4627 flags |= elfcpp::DF_1_NOOPEN;
4628 if (parameters->options().nodump())
4629 flags |= elfcpp::DF_1_NODUMP;
4630 if (!parameters->options().shared())
4631 flags &= ~(elfcpp::DF_1_INITFIRST
4632 | elfcpp::DF_1_NODELETE
4633 | elfcpp::DF_1_NOOPEN);
4634 if (parameters->options().origin())
4635 flags |= elfcpp::DF_1_ORIGIN;
4636 if (parameters->options().now())
4637 flags |= elfcpp::DF_1_NOW;
4638 if (parameters->options().Bgroup())
4639 flags |= elfcpp::DF_1_GROUP;
4641 odyn->add_constant(elfcpp::DT_FLAGS_1, flags);
4644 // Set the size of the _DYNAMIC symbol table to be the size of the
4648 Layout::set_dynamic_symbol_size(const Symbol_table* symtab)
4650 Output_data_dynamic* const odyn = this->dynamic_data_;
4653 odyn->finalize_data_size();
4654 if (this->dynamic_symbol_ == NULL)
4656 off_t data_size = odyn->data_size();
4657 const int size = parameters->target().get_size();
4659 symtab->get_sized_symbol<32>(this->dynamic_symbol_)->set_symsize(data_size);
4660 else if (size == 64)
4661 symtab->get_sized_symbol<64>(this->dynamic_symbol_)->set_symsize(data_size);
4666 // The mapping of input section name prefixes to output section names.
4667 // In some cases one prefix is itself a prefix of another prefix; in
4668 // such a case the longer prefix must come first. These prefixes are
4669 // based on the GNU linker default ELF linker script.
4671 #define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 }
4672 #define MAPPING_INIT_EXACT(f, t) { f, 0, t, sizeof(t) - 1 }
4673 const Layout::Section_name_mapping Layout::section_name_mapping[] =
4675 MAPPING_INIT(".text.", ".text"),
4676 MAPPING_INIT(".rodata.", ".rodata"),
4677 MAPPING_INIT(".data.rel.ro.local.", ".data.rel.ro.local"),
4678 MAPPING_INIT_EXACT(".data.rel.ro.local", ".data.rel.ro.local"),
4679 MAPPING_INIT(".data.rel.ro.", ".data.rel.ro"),
4680 MAPPING_INIT_EXACT(".data.rel.ro", ".data.rel.ro"),
4681 MAPPING_INIT(".data.", ".data"),
4682 MAPPING_INIT(".bss.", ".bss"),
4683 MAPPING_INIT(".tdata.", ".tdata"),
4684 MAPPING_INIT(".tbss.", ".tbss"),
4685 MAPPING_INIT(".init_array.", ".init_array"),
4686 MAPPING_INIT(".fini_array.", ".fini_array"),
4687 MAPPING_INIT(".sdata.", ".sdata"),
4688 MAPPING_INIT(".sbss.", ".sbss"),
4689 // FIXME: In the GNU linker, .sbss2 and .sdata2 are handled
4690 // differently depending on whether it is creating a shared library.
4691 MAPPING_INIT(".sdata2.", ".sdata"),
4692 MAPPING_INIT(".sbss2.", ".sbss"),
4693 MAPPING_INIT(".lrodata.", ".lrodata"),
4694 MAPPING_INIT(".ldata.", ".ldata"),
4695 MAPPING_INIT(".lbss.", ".lbss"),
4696 MAPPING_INIT(".gcc_except_table.", ".gcc_except_table"),
4697 MAPPING_INIT(".gnu.linkonce.d.rel.ro.local.", ".data.rel.ro.local"),
4698 MAPPING_INIT(".gnu.linkonce.d.rel.ro.", ".data.rel.ro"),
4699 MAPPING_INIT(".gnu.linkonce.t.", ".text"),
4700 MAPPING_INIT(".gnu.linkonce.r.", ".rodata"),
4701 MAPPING_INIT(".gnu.linkonce.d.", ".data"),
4702 MAPPING_INIT(".gnu.linkonce.b.", ".bss"),
4703 MAPPING_INIT(".gnu.linkonce.s.", ".sdata"),
4704 MAPPING_INIT(".gnu.linkonce.sb.", ".sbss"),
4705 MAPPING_INIT(".gnu.linkonce.s2.", ".sdata"),
4706 MAPPING_INIT(".gnu.linkonce.sb2.", ".sbss"),
4707 MAPPING_INIT(".gnu.linkonce.wi.", ".debug_info"),
4708 MAPPING_INIT(".gnu.linkonce.td.", ".tdata"),
4709 MAPPING_INIT(".gnu.linkonce.tb.", ".tbss"),
4710 MAPPING_INIT(".gnu.linkonce.lr.", ".lrodata"),
4711 MAPPING_INIT(".gnu.linkonce.l.", ".ldata"),
4712 MAPPING_INIT(".gnu.linkonce.lb.", ".lbss"),
4713 MAPPING_INIT(".ARM.extab", ".ARM.extab"),
4714 MAPPING_INIT(".gnu.linkonce.armextab.", ".ARM.extab"),
4715 MAPPING_INIT(".ARM.exidx", ".ARM.exidx"),
4716 MAPPING_INIT(".gnu.linkonce.armexidx.", ".ARM.exidx"),
4719 #undef MAPPING_INIT_EXACT
4721 const int Layout::section_name_mapping_count =
4722 (sizeof(Layout::section_name_mapping)
4723 / sizeof(Layout::section_name_mapping[0]));
4725 // Choose the output section name to use given an input section name.
4726 // Set *PLEN to the length of the name. *PLEN is initialized to the
4730 Layout::output_section_name(const Relobj* relobj, const char* name,
4733 // gcc 4.3 generates the following sorts of section names when it
4734 // needs a section name specific to a function:
4740 // .data.rel.local.FN
4742 // .data.rel.ro.local.FN
4749 // The GNU linker maps all of those to the part before the .FN,
4750 // except that .data.rel.local.FN is mapped to .data, and
4751 // .data.rel.ro.local.FN is mapped to .data.rel.ro. The sections
4752 // beginning with .data.rel.ro.local are grouped together.
4754 // For an anonymous namespace, the string FN can contain a '.'.
4756 // Also of interest: .rodata.strN.N, .rodata.cstN, both of which the
4757 // GNU linker maps to .rodata.
4759 // The .data.rel.ro sections are used with -z relro. The sections
4760 // are recognized by name. We use the same names that the GNU
4761 // linker does for these sections.
4763 // It is hard to handle this in a principled way, so we don't even
4764 // try. We use a table of mappings. If the input section name is
4765 // not found in the table, we simply use it as the output section
4768 const Section_name_mapping* psnm = section_name_mapping;
4769 for (int i = 0; i < section_name_mapping_count; ++i, ++psnm)
4771 if (psnm->fromlen > 0)
4773 if (strncmp(name, psnm->from, psnm->fromlen) == 0)
4775 *plen = psnm->tolen;
4781 if (strcmp(name, psnm->from) == 0)
4783 *plen = psnm->tolen;
4789 // As an additional complication, .ctors sections are output in
4790 // either .ctors or .init_array sections, and .dtors sections are
4791 // output in either .dtors or .fini_array sections.
4792 if (is_prefix_of(".ctors.", name) || is_prefix_of(".dtors.", name))
4794 if (parameters->options().ctors_in_init_array())
4797 return name[1] == 'c' ? ".init_array" : ".fini_array";
4802 return name[1] == 'c' ? ".ctors" : ".dtors";
4805 if (parameters->options().ctors_in_init_array()
4806 && (strcmp(name, ".ctors") == 0 || strcmp(name, ".dtors") == 0))
4808 // To make .init_array/.fini_array work with gcc we must exclude
4809 // .ctors and .dtors sections from the crtbegin and crtend
4812 || (!Layout::match_file_name(relobj, "crtbegin")
4813 && !Layout::match_file_name(relobj, "crtend")))
4816 return name[1] == 'c' ? ".init_array" : ".fini_array";
4823 // Return true if RELOBJ is an input file whose base name matches
4824 // FILE_NAME. The base name must have an extension of ".o", and must
4825 // be exactly FILE_NAME.o or FILE_NAME, one character, ".o". This is
4826 // to match crtbegin.o as well as crtbeginS.o without getting confused
4827 // by other possibilities. Overall matching the file name this way is
4828 // a dreadful hack, but the GNU linker does it in order to better
4829 // support gcc, and we need to be compatible.
4832 Layout::match_file_name(const Relobj* relobj, const char* match)
4834 const std::string& file_name(relobj->name());
4835 const char* base_name = lbasename(file_name.c_str());
4836 size_t match_len = strlen(match);
4837 if (strncmp(base_name, match, match_len) != 0)
4839 size_t base_len = strlen(base_name);
4840 if (base_len != match_len + 2 && base_len != match_len + 3)
4842 return memcmp(base_name + base_len - 2, ".o", 2) == 0;
4845 // Check if a comdat group or .gnu.linkonce section with the given
4846 // NAME is selected for the link. If there is already a section,
4847 // *KEPT_SECTION is set to point to the existing section and the
4848 // function returns false. Otherwise, OBJECT, SHNDX, IS_COMDAT, and
4849 // IS_GROUP_NAME are recorded for this NAME in the layout object,
4850 // *KEPT_SECTION is set to the internal copy and the function returns
4854 Layout::find_or_add_kept_section(const std::string& name,
4859 Kept_section** kept_section)
4861 // It's normal to see a couple of entries here, for the x86 thunk
4862 // sections. If we see more than a few, we're linking a C++
4863 // program, and we resize to get more space to minimize rehashing.
4864 if (this->signatures_.size() > 4
4865 && !this->resized_signatures_)
4867 reserve_unordered_map(&this->signatures_,
4868 this->number_of_input_files_ * 64);
4869 this->resized_signatures_ = true;
4872 Kept_section candidate;
4873 std::pair<Signatures::iterator, bool> ins =
4874 this->signatures_.insert(std::make_pair(name, candidate));
4876 if (kept_section != NULL)
4877 *kept_section = &ins.first->second;
4880 // This is the first time we've seen this signature.
4881 ins.first->second.set_object(object);
4882 ins.first->second.set_shndx(shndx);
4884 ins.first->second.set_is_comdat();
4886 ins.first->second.set_is_group_name();
4890 // We have already seen this signature.
4892 if (ins.first->second.is_group_name())
4894 // We've already seen a real section group with this signature.
4895 // If the kept group is from a plugin object, and we're in the
4896 // replacement phase, accept the new one as a replacement.
4897 if (ins.first->second.object() == NULL
4898 && parameters->options().plugins()->in_replacement_phase())
4900 ins.first->second.set_object(object);
4901 ins.first->second.set_shndx(shndx);
4906 else if (is_group_name)
4908 // This is a real section group, and we've already seen a
4909 // linkonce section with this signature. Record that we've seen
4910 // a section group, and don't include this section group.
4911 ins.first->second.set_is_group_name();
4916 // We've already seen a linkonce section and this is a linkonce
4917 // section. These don't block each other--this may be the same
4918 // symbol name with different section types.
4923 // Store the allocated sections into the section list.
4926 Layout::get_allocated_sections(Section_list* section_list) const
4928 for (Section_list::const_iterator p = this->section_list_.begin();
4929 p != this->section_list_.end();
4931 if (((*p)->flags() & elfcpp::SHF_ALLOC) != 0)
4932 section_list->push_back(*p);
4935 // Create an output segment.
4938 Layout::make_output_segment(elfcpp::Elf_Word type, elfcpp::Elf_Word flags)
4940 gold_assert(!parameters->options().relocatable());
4941 Output_segment* oseg = new Output_segment(type, flags);
4942 this->segment_list_.push_back(oseg);
4944 if (type == elfcpp::PT_TLS)
4945 this->tls_segment_ = oseg;
4946 else if (type == elfcpp::PT_GNU_RELRO)
4947 this->relro_segment_ = oseg;
4948 else if (type == elfcpp::PT_INTERP)
4949 this->interp_segment_ = oseg;
4954 // Return the file offset of the normal symbol table.
4957 Layout::symtab_section_offset() const
4959 if (this->symtab_section_ != NULL)
4960 return this->symtab_section_->offset();
4964 // Return the section index of the normal symbol table. It may have
4965 // been stripped by the -s/--strip-all option.
4968 Layout::symtab_section_shndx() const
4970 if (this->symtab_section_ != NULL)
4971 return this->symtab_section_->out_shndx();
4975 // Write out the Output_sections. Most won't have anything to write,
4976 // since most of the data will come from input sections which are
4977 // handled elsewhere. But some Output_sections do have Output_data.
4980 Layout::write_output_sections(Output_file* of) const
4982 for (Section_list::const_iterator p = this->section_list_.begin();
4983 p != this->section_list_.end();
4986 if (!(*p)->after_input_sections())
4991 // Write out data not associated with a section or the symbol table.
4994 Layout::write_data(const Symbol_table* symtab, Output_file* of) const
4996 if (!parameters->options().strip_all())
4998 const Output_section* symtab_section = this->symtab_section_;
4999 for (Section_list::const_iterator p = this->section_list_.begin();
5000 p != this->section_list_.end();
5003 if ((*p)->needs_symtab_index())
5005 gold_assert(symtab_section != NULL);
5006 unsigned int index = (*p)->symtab_index();
5007 gold_assert(index > 0 && index != -1U);
5008 off_t off = (symtab_section->offset()
5009 + index * symtab_section->entsize());
5010 symtab->write_section_symbol(*p, this->symtab_xindex_, of, off);
5015 const Output_section* dynsym_section = this->dynsym_section_;
5016 for (Section_list::const_iterator p = this->section_list_.begin();
5017 p != this->section_list_.end();
5020 if ((*p)->needs_dynsym_index())
5022 gold_assert(dynsym_section != NULL);
5023 unsigned int index = (*p)->dynsym_index();
5024 gold_assert(index > 0 && index != -1U);
5025 off_t off = (dynsym_section->offset()
5026 + index * dynsym_section->entsize());
5027 symtab->write_section_symbol(*p, this->dynsym_xindex_, of, off);
5031 // Write out the Output_data which are not in an Output_section.
5032 for (Data_list::const_iterator p = this->special_output_list_.begin();
5033 p != this->special_output_list_.end();
5038 // Write out the Output_sections which can only be written after the
5039 // input sections are complete.
5042 Layout::write_sections_after_input_sections(Output_file* of)
5044 // Determine the final section offsets, and thus the final output
5045 // file size. Note we finalize the .shstrab last, to allow the
5046 // after_input_section sections to modify their section-names before
5048 if (this->any_postprocessing_sections_)
5050 off_t off = this->output_file_size_;
5051 off = this->set_section_offsets(off, POSTPROCESSING_SECTIONS_PASS);
5053 // Now that we've finalized the names, we can finalize the shstrab.
5055 this->set_section_offsets(off,
5056 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS);
5058 if (off > this->output_file_size_)
5061 this->output_file_size_ = off;
5065 for (Section_list::const_iterator p = this->section_list_.begin();
5066 p != this->section_list_.end();
5069 if ((*p)->after_input_sections())
5073 this->section_headers_->write(of);
5076 // If the build ID requires computing a checksum, do so here, and
5077 // write it out. We compute a checksum over the entire file because
5078 // that is simplest.
5081 Layout::write_build_id(Output_file* of) const
5083 if (this->build_id_note_ == NULL)
5086 const unsigned char* iv = of->get_input_view(0, this->output_file_size_);
5088 unsigned char* ov = of->get_output_view(this->build_id_note_->offset(),
5089 this->build_id_note_->data_size());
5091 const char* style = parameters->options().build_id();
5092 if (strcmp(style, "sha1") == 0)
5095 sha1_init_ctx(&ctx);
5096 sha1_process_bytes(iv, this->output_file_size_, &ctx);
5097 sha1_finish_ctx(&ctx, ov);
5099 else if (strcmp(style, "md5") == 0)
5103 md5_process_bytes(iv, this->output_file_size_, &ctx);
5104 md5_finish_ctx(&ctx, ov);
5109 of->write_output_view(this->build_id_note_->offset(),
5110 this->build_id_note_->data_size(),
5113 of->free_input_view(0, this->output_file_size_, iv);
5116 // Write out a binary file. This is called after the link is
5117 // complete. IN is the temporary output file we used to generate the
5118 // ELF code. We simply walk through the segments, read them from
5119 // their file offset in IN, and write them to their load address in
5120 // the output file. FIXME: with a bit more work, we could support
5121 // S-records and/or Intel hex format here.
5124 Layout::write_binary(Output_file* in) const
5126 gold_assert(parameters->options().oformat_enum()
5127 == General_options::OBJECT_FORMAT_BINARY);
5129 // Get the size of the binary file.
5130 uint64_t max_load_address = 0;
5131 for (Segment_list::const_iterator p = this->segment_list_.begin();
5132 p != this->segment_list_.end();
5135 if ((*p)->type() == elfcpp::PT_LOAD && (*p)->filesz() > 0)
5137 uint64_t max_paddr = (*p)->paddr() + (*p)->filesz();
5138 if (max_paddr > max_load_address)
5139 max_load_address = max_paddr;
5143 Output_file out(parameters->options().output_file_name());
5144 out.open(max_load_address);
5146 for (Segment_list::const_iterator p = this->segment_list_.begin();
5147 p != this->segment_list_.end();
5150 if ((*p)->type() == elfcpp::PT_LOAD && (*p)->filesz() > 0)
5152 const unsigned char* vin = in->get_input_view((*p)->offset(),
5154 unsigned char* vout = out.get_output_view((*p)->paddr(),
5156 memcpy(vout, vin, (*p)->filesz());
5157 out.write_output_view((*p)->paddr(), (*p)->filesz(), vout);
5158 in->free_input_view((*p)->offset(), (*p)->filesz(), vin);
5165 // Print the output sections to the map file.
5168 Layout::print_to_mapfile(Mapfile* mapfile) const
5170 for (Segment_list::const_iterator p = this->segment_list_.begin();
5171 p != this->segment_list_.end();
5173 (*p)->print_sections_to_mapfile(mapfile);
5176 // Print statistical information to stderr. This is used for --stats.
5179 Layout::print_stats() const
5181 this->namepool_.print_stats("section name pool");
5182 this->sympool_.print_stats("output symbol name pool");
5183 this->dynpool_.print_stats("dynamic name pool");
5185 for (Section_list::const_iterator p = this->section_list_.begin();
5186 p != this->section_list_.end();
5188 (*p)->print_merge_stats();
5191 // Write_sections_task methods.
5193 // We can always run this task.
5196 Write_sections_task::is_runnable()
5201 // We need to unlock both OUTPUT_SECTIONS_BLOCKER and FINAL_BLOCKER
5205 Write_sections_task::locks(Task_locker* tl)
5207 tl->add(this, this->output_sections_blocker_);
5208 tl->add(this, this->final_blocker_);
5211 // Run the task--write out the data.
5214 Write_sections_task::run(Workqueue*)
5216 this->layout_->write_output_sections(this->of_);
5219 // Write_data_task methods.
5221 // We can always run this task.
5224 Write_data_task::is_runnable()
5229 // We need to unlock FINAL_BLOCKER when finished.
5232 Write_data_task::locks(Task_locker* tl)
5234 tl->add(this, this->final_blocker_);
5237 // Run the task--write out the data.
5240 Write_data_task::run(Workqueue*)
5242 this->layout_->write_data(this->symtab_, this->of_);
5245 // Write_symbols_task methods.
5247 // We can always run this task.
5250 Write_symbols_task::is_runnable()
5255 // We need to unlock FINAL_BLOCKER when finished.
5258 Write_symbols_task::locks(Task_locker* tl)
5260 tl->add(this, this->final_blocker_);
5263 // Run the task--write out the symbols.
5266 Write_symbols_task::run(Workqueue*)
5268 this->symtab_->write_globals(this->sympool_, this->dynpool_,
5269 this->layout_->symtab_xindex(),
5270 this->layout_->dynsym_xindex(), this->of_);
5273 // Write_after_input_sections_task methods.
5275 // We can only run this task after the input sections have completed.
5278 Write_after_input_sections_task::is_runnable()
5280 if (this->input_sections_blocker_->is_blocked())
5281 return this->input_sections_blocker_;
5285 // We need to unlock FINAL_BLOCKER when finished.
5288 Write_after_input_sections_task::locks(Task_locker* tl)
5290 tl->add(this, this->final_blocker_);
5296 Write_after_input_sections_task::run(Workqueue*)
5298 this->layout_->write_sections_after_input_sections(this->of_);
5301 // Close_task_runner methods.
5303 // Run the task--close the file.
5306 Close_task_runner::run(Workqueue*, const Task*)
5308 // If we need to compute a checksum for the BUILD if, we do so here.
5309 this->layout_->write_build_id(this->of_);
5311 // If we've been asked to create a binary file, we do so here.
5312 if (this->options_->oformat_enum() != General_options::OBJECT_FORMAT_ELF)
5313 this->layout_->write_binary(this->of_);
5318 // Instantiate the templates we need. We could use the configure
5319 // script to restrict this to only the ones for implemented targets.
5321 #ifdef HAVE_TARGET_32_LITTLE
5324 Layout::init_fixed_output_section<32, false>(
5326 elfcpp::Shdr<32, false>& shdr);
5329 #ifdef HAVE_TARGET_32_BIG
5332 Layout::init_fixed_output_section<32, true>(
5334 elfcpp::Shdr<32, true>& shdr);
5337 #ifdef HAVE_TARGET_64_LITTLE
5340 Layout::init_fixed_output_section<64, false>(
5342 elfcpp::Shdr<64, false>& shdr);
5345 #ifdef HAVE_TARGET_64_BIG
5348 Layout::init_fixed_output_section<64, true>(
5350 elfcpp::Shdr<64, true>& shdr);
5353 #ifdef HAVE_TARGET_32_LITTLE
5356 Layout::layout<32, false>(Sized_relobj_file<32, false>* object,
5359 const elfcpp::Shdr<32, false>& shdr,
5360 unsigned int, unsigned int, off_t*);
5363 #ifdef HAVE_TARGET_32_BIG
5366 Layout::layout<32, true>(Sized_relobj_file<32, true>* object,
5369 const elfcpp::Shdr<32, true>& shdr,
5370 unsigned int, unsigned int, off_t*);
5373 #ifdef HAVE_TARGET_64_LITTLE
5376 Layout::layout<64, false>(Sized_relobj_file<64, false>* object,
5379 const elfcpp::Shdr<64, false>& shdr,
5380 unsigned int, unsigned int, off_t*);
5383 #ifdef HAVE_TARGET_64_BIG
5386 Layout::layout<64, true>(Sized_relobj_file<64, true>* object,
5389 const elfcpp::Shdr<64, true>& shdr,
5390 unsigned int, unsigned int, off_t*);
5393 #ifdef HAVE_TARGET_32_LITTLE
5396 Layout::layout_reloc<32, false>(Sized_relobj_file<32, false>* object,
5397 unsigned int reloc_shndx,
5398 const elfcpp::Shdr<32, false>& shdr,
5399 Output_section* data_section,
5400 Relocatable_relocs* rr);
5403 #ifdef HAVE_TARGET_32_BIG
5406 Layout::layout_reloc<32, true>(Sized_relobj_file<32, true>* object,
5407 unsigned int reloc_shndx,
5408 const elfcpp::Shdr<32, true>& shdr,
5409 Output_section* data_section,
5410 Relocatable_relocs* rr);
5413 #ifdef HAVE_TARGET_64_LITTLE
5416 Layout::layout_reloc<64, false>(Sized_relobj_file<64, false>* object,
5417 unsigned int reloc_shndx,
5418 const elfcpp::Shdr<64, false>& shdr,
5419 Output_section* data_section,
5420 Relocatable_relocs* rr);
5423 #ifdef HAVE_TARGET_64_BIG
5426 Layout::layout_reloc<64, true>(Sized_relobj_file<64, true>* object,
5427 unsigned int reloc_shndx,
5428 const elfcpp::Shdr<64, true>& shdr,
5429 Output_section* data_section,
5430 Relocatable_relocs* rr);
5433 #ifdef HAVE_TARGET_32_LITTLE
5436 Layout::layout_group<32, false>(Symbol_table* symtab,
5437 Sized_relobj_file<32, false>* object,
5439 const char* group_section_name,
5440 const char* signature,
5441 const elfcpp::Shdr<32, false>& shdr,
5442 elfcpp::Elf_Word flags,
5443 std::vector<unsigned int>* shndxes);
5446 #ifdef HAVE_TARGET_32_BIG
5449 Layout::layout_group<32, true>(Symbol_table* symtab,
5450 Sized_relobj_file<32, true>* object,
5452 const char* group_section_name,
5453 const char* signature,
5454 const elfcpp::Shdr<32, true>& shdr,
5455 elfcpp::Elf_Word flags,
5456 std::vector<unsigned int>* shndxes);
5459 #ifdef HAVE_TARGET_64_LITTLE
5462 Layout::layout_group<64, false>(Symbol_table* symtab,
5463 Sized_relobj_file<64, false>* object,
5465 const char* group_section_name,
5466 const char* signature,
5467 const elfcpp::Shdr<64, false>& shdr,
5468 elfcpp::Elf_Word flags,
5469 std::vector<unsigned int>* shndxes);
5472 #ifdef HAVE_TARGET_64_BIG
5475 Layout::layout_group<64, true>(Symbol_table* symtab,
5476 Sized_relobj_file<64, true>* object,
5478 const char* group_section_name,
5479 const char* signature,
5480 const elfcpp::Shdr<64, true>& shdr,
5481 elfcpp::Elf_Word flags,
5482 std::vector<unsigned int>* shndxes);
5485 #ifdef HAVE_TARGET_32_LITTLE
5488 Layout::layout_eh_frame<32, false>(Sized_relobj_file<32, false>* object,
5489 const unsigned char* symbols,
5491 const unsigned char* symbol_names,
5492 off_t symbol_names_size,
5494 const elfcpp::Shdr<32, false>& shdr,
5495 unsigned int reloc_shndx,
5496 unsigned int reloc_type,
5500 #ifdef HAVE_TARGET_32_BIG
5503 Layout::layout_eh_frame<32, true>(Sized_relobj_file<32, true>* object,
5504 const unsigned char* symbols,
5506 const unsigned char* symbol_names,
5507 off_t symbol_names_size,
5509 const elfcpp::Shdr<32, true>& shdr,
5510 unsigned int reloc_shndx,
5511 unsigned int reloc_type,
5515 #ifdef HAVE_TARGET_64_LITTLE
5518 Layout::layout_eh_frame<64, false>(Sized_relobj_file<64, false>* object,
5519 const unsigned char* symbols,
5521 const unsigned char* symbol_names,
5522 off_t symbol_names_size,
5524 const elfcpp::Shdr<64, false>& shdr,
5525 unsigned int reloc_shndx,
5526 unsigned int reloc_type,
5530 #ifdef HAVE_TARGET_64_BIG
5533 Layout::layout_eh_frame<64, true>(Sized_relobj_file<64, true>* object,
5534 const unsigned char* symbols,
5536 const unsigned char* symbol_names,
5537 off_t symbol_names_size,
5539 const elfcpp::Shdr<64, true>& shdr,
5540 unsigned int reloc_shndx,
5541 unsigned int reloc_type,
5545 #ifdef HAVE_TARGET_32_LITTLE
5548 Layout::add_to_gdb_index(bool is_type_unit,
5549 Sized_relobj<32, false>* object,
5550 const unsigned char* symbols,
5553 unsigned int reloc_shndx,
5554 unsigned int reloc_type);
5557 #ifdef HAVE_TARGET_32_BIG
5560 Layout::add_to_gdb_index(bool is_type_unit,
5561 Sized_relobj<32, true>* object,
5562 const unsigned char* symbols,
5565 unsigned int reloc_shndx,
5566 unsigned int reloc_type);
5569 #ifdef HAVE_TARGET_64_LITTLE
5572 Layout::add_to_gdb_index(bool is_type_unit,
5573 Sized_relobj<64, false>* object,
5574 const unsigned char* symbols,
5577 unsigned int reloc_shndx,
5578 unsigned int reloc_type);
5581 #ifdef HAVE_TARGET_64_BIG
5584 Layout::add_to_gdb_index(bool is_type_unit,
5585 Sized_relobj<64, true>* object,
5586 const unsigned char* symbols,
5589 unsigned int reloc_shndx,
5590 unsigned int reloc_type);
5593 } // End namespace gold.