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());
612 case elfcpp::SHT_PROGBITS:
613 if (parameters->options().strip_debug()
614 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
616 if (is_debug_info_section(name))
619 if (parameters->options().strip_debug_non_line()
620 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
622 // Debugging sections can only be recognized by name.
623 if (is_prefix_of(".debug_", name)
624 && !is_lines_only_debug_section(name + 7))
626 if (is_prefix_of(".zdebug_", name)
627 && !is_lines_only_debug_section(name + 8))
630 if (parameters->options().strip_debug_gdb()
631 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
633 // Debugging sections can only be recognized by name.
634 if (is_prefix_of(".debug_", name)
635 && !is_gdb_debug_section(name + 7))
637 if (is_prefix_of(".zdebug_", name)
638 && !is_gdb_debug_section(name + 8))
641 if (parameters->options().gdb_index()
642 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
644 // When building .gdb_index, we can strip .debug_pubnames,
645 // .debug_pubtypes, and .debug_aranges sections.
646 if (is_prefix_of(".debug_", name)
647 && is_gdb_fast_lookup_section(name + 7))
649 if (is_prefix_of(".zdebug_", name)
650 && is_gdb_fast_lookup_section(name + 8))
653 if (parameters->options().strip_lto_sections()
654 && !parameters->options().relocatable()
655 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
657 // Ignore LTO sections containing intermediate code.
658 if (is_prefix_of(".gnu.lto_", name))
661 // The GNU linker strips .gnu_debuglink sections, so we do too.
662 // This is a feature used to keep debugging information in
664 if (strcmp(name, ".gnu_debuglink") == 0)
673 // Return an output section named NAME, or NULL if there is none.
676 Layout::find_output_section(const char* name) const
678 for (Section_list::const_iterator p = this->section_list_.begin();
679 p != this->section_list_.end();
681 if (strcmp((*p)->name(), name) == 0)
686 // Return an output segment of type TYPE, with segment flags SET set
687 // and segment flags CLEAR clear. Return NULL if there is none.
690 Layout::find_output_segment(elfcpp::PT type, elfcpp::Elf_Word set,
691 elfcpp::Elf_Word clear) const
693 for (Segment_list::const_iterator p = this->segment_list_.begin();
694 p != this->segment_list_.end();
696 if (static_cast<elfcpp::PT>((*p)->type()) == type
697 && ((*p)->flags() & set) == set
698 && ((*p)->flags() & clear) == 0)
703 // When we put a .ctors or .dtors section with more than one word into
704 // a .init_array or .fini_array section, we need to reverse the words
705 // in the .ctors/.dtors section. This is because .init_array executes
706 // constructors front to back, where .ctors executes them back to
707 // front, and vice-versa for .fini_array/.dtors. Although we do want
708 // to remap .ctors/.dtors into .init_array/.fini_array because it can
709 // be more efficient, we don't want to change the order in which
710 // constructors/destructors are run. This set just keeps track of
711 // these sections which need to be reversed. It is only changed by
712 // Layout::layout. It should be a private member of Layout, but that
713 // would require layout.h to #include object.h to get the definition
715 static Unordered_set<Section_id, Section_id_hash> ctors_sections_in_init_array;
717 // Return whether OBJECT/SHNDX is a .ctors/.dtors section mapped to a
718 // .init_array/.fini_array section.
721 Layout::is_ctors_in_init_array(Relobj* relobj, unsigned int shndx) const
723 return (ctors_sections_in_init_array.find(Section_id(relobj, shndx))
724 != ctors_sections_in_init_array.end());
727 // Return the output section to use for section NAME with type TYPE
728 // and section flags FLAGS. NAME must be canonicalized in the string
729 // pool, and NAME_KEY is the key. ORDER is where this should appear
730 // in the output sections. IS_RELRO is true for a relro section.
733 Layout::get_output_section(const char* name, Stringpool::Key name_key,
734 elfcpp::Elf_Word type, elfcpp::Elf_Xword flags,
735 Output_section_order order, bool is_relro)
737 elfcpp::Elf_Word lookup_type = type;
739 // For lookup purposes, treat INIT_ARRAY, FINI_ARRAY, and
740 // PREINIT_ARRAY like PROGBITS. This ensures that we combine
741 // .init_array, .fini_array, and .preinit_array sections by name
742 // whatever their type in the input file. We do this because the
743 // types are not always right in the input files.
744 if (lookup_type == elfcpp::SHT_INIT_ARRAY
745 || lookup_type == elfcpp::SHT_FINI_ARRAY
746 || lookup_type == elfcpp::SHT_PREINIT_ARRAY)
747 lookup_type = elfcpp::SHT_PROGBITS;
749 elfcpp::Elf_Xword lookup_flags = flags;
751 // Ignoring SHF_WRITE and SHF_EXECINSTR here means that we combine
752 // read-write with read-only sections. Some other ELF linkers do
753 // not do this. FIXME: Perhaps there should be an option
755 lookup_flags &= ~(elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR);
757 const Key key(name_key, std::make_pair(lookup_type, lookup_flags));
758 const std::pair<Key, Output_section*> v(key, NULL);
759 std::pair<Section_name_map::iterator, bool> ins(
760 this->section_name_map_.insert(v));
763 return ins.first->second;
766 // This is the first time we've seen this name/type/flags
767 // combination. For compatibility with the GNU linker, we
768 // combine sections with contents and zero flags with sections
769 // with non-zero flags. This is a workaround for cases where
770 // assembler code forgets to set section flags. FIXME: Perhaps
771 // there should be an option to control this.
772 Output_section* os = NULL;
774 if (lookup_type == elfcpp::SHT_PROGBITS)
778 Output_section* same_name = this->find_output_section(name);
779 if (same_name != NULL
780 && (same_name->type() == elfcpp::SHT_PROGBITS
781 || same_name->type() == elfcpp::SHT_INIT_ARRAY
782 || same_name->type() == elfcpp::SHT_FINI_ARRAY
783 || same_name->type() == elfcpp::SHT_PREINIT_ARRAY)
784 && (same_name->flags() & elfcpp::SHF_TLS) == 0)
787 else if ((flags & elfcpp::SHF_TLS) == 0)
789 elfcpp::Elf_Xword zero_flags = 0;
790 const Key zero_key(name_key, std::make_pair(lookup_type,
792 Section_name_map::iterator p =
793 this->section_name_map_.find(zero_key);
794 if (p != this->section_name_map_.end())
800 os = this->make_output_section(name, type, flags, order, is_relro);
802 ins.first->second = os;
807 // Returns TRUE iff NAME (an input section from RELOBJ) will
808 // be mapped to an output section that should be KEPT.
811 Layout::keep_input_section(const Relobj* relobj, const char* name)
813 if (! this->script_options_->saw_sections_clause())
816 Script_sections* ss = this->script_options_->script_sections();
817 const char* file_name = relobj == NULL ? NULL : relobj->name().c_str();
818 Output_section** output_section_slot;
819 Script_sections::Section_type script_section_type;
822 name = ss->output_section_name(file_name, name, &output_section_slot,
823 &script_section_type, &keep);
824 return name != NULL && keep;
827 // Pick the output section to use for section NAME, in input file
828 // RELOBJ, with type TYPE and flags FLAGS. RELOBJ may be NULL for a
829 // linker created section. IS_INPUT_SECTION is true if we are
830 // choosing an output section for an input section found in a input
831 // file. ORDER is where this section should appear in the output
832 // sections. IS_RELRO is true for a relro section. This will return
833 // NULL if the input section should be discarded.
836 Layout::choose_output_section(const Relobj* relobj, const char* name,
837 elfcpp::Elf_Word type, elfcpp::Elf_Xword flags,
838 bool is_input_section, Output_section_order order,
841 // We should not see any input sections after we have attached
842 // sections to segments.
843 gold_assert(!is_input_section || !this->sections_are_attached_);
845 // Some flags in the input section should not be automatically
846 // copied to the output section.
847 flags &= ~ (elfcpp::SHF_INFO_LINK
850 | elfcpp::SHF_STRINGS);
852 // We only clear the SHF_LINK_ORDER flag in for
853 // a non-relocatable link.
854 if (!parameters->options().relocatable())
855 flags &= ~elfcpp::SHF_LINK_ORDER;
857 if (this->script_options_->saw_sections_clause())
859 // We are using a SECTIONS clause, so the output section is
860 // chosen based only on the name.
862 Script_sections* ss = this->script_options_->script_sections();
863 const char* file_name = relobj == NULL ? NULL : relobj->name().c_str();
864 Output_section** output_section_slot;
865 Script_sections::Section_type script_section_type;
866 const char* orig_name = name;
868 name = ss->output_section_name(file_name, name, &output_section_slot,
869 &script_section_type, &keep);
873 gold_debug(DEBUG_SCRIPT, _("Unable to create output section '%s' "
874 "because it is not allowed by the "
875 "SECTIONS clause of the linker script"),
877 // The SECTIONS clause says to discard this input section.
881 // We can only handle script section types ST_NONE and ST_NOLOAD.
882 switch (script_section_type)
884 case Script_sections::ST_NONE:
886 case Script_sections::ST_NOLOAD:
887 flags &= elfcpp::SHF_ALLOC;
893 // If this is an orphan section--one not mentioned in the linker
894 // script--then OUTPUT_SECTION_SLOT will be NULL, and we do the
895 // default processing below.
897 if (output_section_slot != NULL)
899 if (*output_section_slot != NULL)
901 (*output_section_slot)->update_flags_for_input_section(flags);
902 return *output_section_slot;
905 // We don't put sections found in the linker script into
906 // SECTION_NAME_MAP_. That keeps us from getting confused
907 // if an orphan section is mapped to a section with the same
908 // name as one in the linker script.
910 name = this->namepool_.add(name, false, NULL);
912 Output_section* os = this->make_output_section(name, type, flags,
915 os->set_found_in_sections_clause();
917 // Special handling for NOLOAD sections.
918 if (script_section_type == Script_sections::ST_NOLOAD)
922 // The constructor of Output_section sets addresses of non-ALLOC
923 // sections to 0 by default. We don't want that for NOLOAD
924 // sections even if they have no SHF_ALLOC flag.
925 if ((os->flags() & elfcpp::SHF_ALLOC) == 0
926 && os->is_address_valid())
928 gold_assert(os->address() == 0
929 && !os->is_offset_valid()
930 && !os->is_data_size_valid());
931 os->reset_address_and_file_offset();
935 *output_section_slot = os;
940 // FIXME: Handle SHF_OS_NONCONFORMING somewhere.
942 size_t len = strlen(name);
943 char* uncompressed_name = NULL;
945 // Compressed debug sections should be mapped to the corresponding
946 // uncompressed section.
947 if (is_compressed_debug_section(name))
949 uncompressed_name = new char[len];
950 uncompressed_name[0] = '.';
951 gold_assert(name[0] == '.' && name[1] == 'z');
952 strncpy(&uncompressed_name[1], &name[2], len - 2);
953 uncompressed_name[len - 1] = '\0';
955 name = uncompressed_name;
958 // Turn NAME from the name of the input section into the name of the
961 && !this->script_options_->saw_sections_clause()
962 && !parameters->options().relocatable())
964 const char *orig_name = name;
965 name = parameters->target().output_section_name(relobj, name, &len);
967 name = Layout::output_section_name(relobj, orig_name, &len);
970 Stringpool::Key name_key;
971 name = this->namepool_.add_with_length(name, len, true, &name_key);
973 if (uncompressed_name != NULL)
974 delete[] uncompressed_name;
976 // Find or make the output section. The output section is selected
977 // based on the section name, type, and flags.
978 return this->get_output_section(name, name_key, type, flags, order, is_relro);
981 // For incremental links, record the initial fixed layout of a section
982 // from the base file, and return a pointer to the Output_section.
984 template<int size, bool big_endian>
986 Layout::init_fixed_output_section(const char* name,
987 elfcpp::Shdr<size, big_endian>& shdr)
989 unsigned int sh_type = shdr.get_sh_type();
991 // We preserve the layout of PROGBITS, NOBITS, INIT_ARRAY, FINI_ARRAY,
992 // PRE_INIT_ARRAY, and NOTE sections.
993 // All others will be created from scratch and reallocated.
994 if (!can_incremental_update(sh_type))
997 // If we're generating a .gdb_index section, we need to regenerate
999 if (parameters->options().gdb_index()
1000 && sh_type == elfcpp::SHT_PROGBITS
1001 && strcmp(name, ".gdb_index") == 0)
1004 typename elfcpp::Elf_types<size>::Elf_Addr sh_addr = shdr.get_sh_addr();
1005 typename elfcpp::Elf_types<size>::Elf_Off sh_offset = shdr.get_sh_offset();
1006 typename elfcpp::Elf_types<size>::Elf_WXword sh_size = shdr.get_sh_size();
1007 typename elfcpp::Elf_types<size>::Elf_WXword sh_flags = shdr.get_sh_flags();
1008 typename elfcpp::Elf_types<size>::Elf_WXword sh_addralign =
1009 shdr.get_sh_addralign();
1011 // Make the output section.
1012 Stringpool::Key name_key;
1013 name = this->namepool_.add(name, true, &name_key);
1014 Output_section* os = this->get_output_section(name, name_key, sh_type,
1015 sh_flags, ORDER_INVALID, false);
1016 os->set_fixed_layout(sh_addr, sh_offset, sh_size, sh_addralign);
1017 if (sh_type != elfcpp::SHT_NOBITS)
1018 this->free_list_.remove(sh_offset, sh_offset + sh_size);
1022 // Return the output section to use for input section SHNDX, with name
1023 // NAME, with header HEADER, from object OBJECT. RELOC_SHNDX is the
1024 // index of a relocation section which applies to this section, or 0
1025 // if none, or -1U if more than one. RELOC_TYPE is the type of the
1026 // relocation section if there is one. Set *OFF to the offset of this
1027 // input section without the output section. Return NULL if the
1028 // section should be discarded. Set *OFF to -1 if the section
1029 // contents should not be written directly to the output file, but
1030 // will instead receive special handling.
1032 template<int size, bool big_endian>
1034 Layout::layout(Sized_relobj_file<size, big_endian>* object, unsigned int shndx,
1035 const char* name, const elfcpp::Shdr<size, big_endian>& shdr,
1036 unsigned int reloc_shndx, unsigned int, off_t* off)
1040 if (!this->include_section(object, name, shdr))
1043 elfcpp::Elf_Word sh_type = shdr.get_sh_type();
1045 // In a relocatable link a grouped section must not be combined with
1046 // any other sections.
1048 if (parameters->options().relocatable()
1049 && (shdr.get_sh_flags() & elfcpp::SHF_GROUP) != 0)
1051 name = this->namepool_.add(name, true, NULL);
1052 os = this->make_output_section(name, sh_type, shdr.get_sh_flags(),
1053 ORDER_INVALID, false);
1057 os = this->choose_output_section(object, name, sh_type,
1058 shdr.get_sh_flags(), true,
1059 ORDER_INVALID, false);
1064 // By default the GNU linker sorts input sections whose names match
1065 // .ctors.*, .dtors.*, .init_array.*, or .fini_array.*. The
1066 // sections are sorted by name. This is used to implement
1067 // constructor priority ordering. We are compatible. When we put
1068 // .ctor sections in .init_array and .dtor sections in .fini_array,
1069 // we must also sort plain .ctor and .dtor sections.
1070 if (!this->script_options_->saw_sections_clause()
1071 && !parameters->options().relocatable()
1072 && (is_prefix_of(".ctors.", name)
1073 || is_prefix_of(".dtors.", name)
1074 || is_prefix_of(".init_array.", name)
1075 || is_prefix_of(".fini_array.", name)
1076 || (parameters->options().ctors_in_init_array()
1077 && (strcmp(name, ".ctors") == 0
1078 || strcmp(name, ".dtors") == 0))))
1079 os->set_must_sort_attached_input_sections();
1081 // If this is a .ctors or .ctors.* section being mapped to a
1082 // .init_array section, or a .dtors or .dtors.* section being mapped
1083 // to a .fini_array section, we will need to reverse the words if
1084 // there is more than one. Record this section for later. See
1085 // ctors_sections_in_init_array above.
1086 if (!this->script_options_->saw_sections_clause()
1087 && !parameters->options().relocatable()
1088 && shdr.get_sh_size() > size / 8
1089 && (((strcmp(name, ".ctors") == 0
1090 || is_prefix_of(".ctors.", name))
1091 && strcmp(os->name(), ".init_array") == 0)
1092 || ((strcmp(name, ".dtors") == 0
1093 || is_prefix_of(".dtors.", name))
1094 && strcmp(os->name(), ".fini_array") == 0)))
1095 ctors_sections_in_init_array.insert(Section_id(object, shndx));
1097 // FIXME: Handle SHF_LINK_ORDER somewhere.
1099 elfcpp::Elf_Xword orig_flags = os->flags();
1101 *off = os->add_input_section(this, object, shndx, name, shdr, reloc_shndx,
1102 this->script_options_->saw_sections_clause());
1104 // If the flags changed, we may have to change the order.
1105 if ((orig_flags & elfcpp::SHF_ALLOC) != 0)
1107 orig_flags &= (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR);
1108 elfcpp::Elf_Xword new_flags =
1109 os->flags() & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR);
1110 if (orig_flags != new_flags)
1111 os->set_order(this->default_section_order(os, false));
1114 this->have_added_input_section_ = true;
1119 // Handle a relocation section when doing a relocatable link.
1121 template<int size, bool big_endian>
1123 Layout::layout_reloc(Sized_relobj_file<size, big_endian>* object,
1125 const elfcpp::Shdr<size, big_endian>& shdr,
1126 Output_section* data_section,
1127 Relocatable_relocs* rr)
1129 gold_assert(parameters->options().relocatable()
1130 || parameters->options().emit_relocs());
1132 int sh_type = shdr.get_sh_type();
1135 if (sh_type == elfcpp::SHT_REL)
1137 else if (sh_type == elfcpp::SHT_RELA)
1141 name += data_section->name();
1143 // In a relocatable link relocs for a grouped section must not be
1144 // combined with other reloc sections.
1146 if (!parameters->options().relocatable()
1147 || (data_section->flags() & elfcpp::SHF_GROUP) == 0)
1148 os = this->choose_output_section(object, name.c_str(), sh_type,
1149 shdr.get_sh_flags(), false,
1150 ORDER_INVALID, false);
1153 const char* n = this->namepool_.add(name.c_str(), true, NULL);
1154 os = this->make_output_section(n, sh_type, shdr.get_sh_flags(),
1155 ORDER_INVALID, false);
1158 os->set_should_link_to_symtab();
1159 os->set_info_section(data_section);
1161 Output_section_data* posd;
1162 if (sh_type == elfcpp::SHT_REL)
1164 os->set_entsize(elfcpp::Elf_sizes<size>::rel_size);
1165 posd = new Output_relocatable_relocs<elfcpp::SHT_REL,
1169 else if (sh_type == elfcpp::SHT_RELA)
1171 os->set_entsize(elfcpp::Elf_sizes<size>::rela_size);
1172 posd = new Output_relocatable_relocs<elfcpp::SHT_RELA,
1179 os->add_output_section_data(posd);
1180 rr->set_output_data(posd);
1185 // Handle a group section when doing a relocatable link.
1187 template<int size, bool big_endian>
1189 Layout::layout_group(Symbol_table* symtab,
1190 Sized_relobj_file<size, big_endian>* object,
1192 const char* group_section_name,
1193 const char* signature,
1194 const elfcpp::Shdr<size, big_endian>& shdr,
1195 elfcpp::Elf_Word flags,
1196 std::vector<unsigned int>* shndxes)
1198 gold_assert(parameters->options().relocatable());
1199 gold_assert(shdr.get_sh_type() == elfcpp::SHT_GROUP);
1200 group_section_name = this->namepool_.add(group_section_name, true, NULL);
1201 Output_section* os = this->make_output_section(group_section_name,
1203 shdr.get_sh_flags(),
1204 ORDER_INVALID, false);
1206 // We need to find a symbol with the signature in the symbol table.
1207 // If we don't find one now, we need to look again later.
1208 Symbol* sym = symtab->lookup(signature, NULL);
1210 os->set_info_symndx(sym);
1213 // Reserve some space to minimize reallocations.
1214 if (this->group_signatures_.empty())
1215 this->group_signatures_.reserve(this->number_of_input_files_ * 16);
1217 // We will wind up using a symbol whose name is the signature.
1218 // So just put the signature in the symbol name pool to save it.
1219 signature = symtab->canonicalize_name(signature);
1220 this->group_signatures_.push_back(Group_signature(os, signature));
1223 os->set_should_link_to_symtab();
1226 section_size_type entry_count =
1227 convert_to_section_size_type(shdr.get_sh_size() / 4);
1228 Output_section_data* posd =
1229 new Output_data_group<size, big_endian>(object, entry_count, flags,
1231 os->add_output_section_data(posd);
1234 // Special GNU handling of sections name .eh_frame. They will
1235 // normally hold exception frame data as defined by the C++ ABI
1236 // (http://codesourcery.com/cxx-abi/).
1238 template<int size, bool big_endian>
1240 Layout::layout_eh_frame(Sized_relobj_file<size, big_endian>* object,
1241 const unsigned char* symbols,
1243 const unsigned char* symbol_names,
1244 off_t symbol_names_size,
1246 const elfcpp::Shdr<size, big_endian>& shdr,
1247 unsigned int reloc_shndx, unsigned int reloc_type,
1250 gold_assert(shdr.get_sh_type() == elfcpp::SHT_PROGBITS
1251 || shdr.get_sh_type() == elfcpp::SHT_X86_64_UNWIND);
1252 gold_assert((shdr.get_sh_flags() & elfcpp::SHF_ALLOC) != 0);
1254 Output_section* os = this->make_eh_frame_section(object);
1258 gold_assert(this->eh_frame_section_ == os);
1260 elfcpp::Elf_Xword orig_flags = os->flags();
1262 if (!parameters->incremental()
1263 && this->eh_frame_data_->add_ehframe_input_section(object,
1272 os->update_flags_for_input_section(shdr.get_sh_flags());
1274 // A writable .eh_frame section is a RELRO section.
1275 if ((orig_flags & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR))
1276 != (os->flags() & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR)))
1279 os->set_order(ORDER_RELRO);
1282 // We found a .eh_frame section we are going to optimize, so now
1283 // we can add the set of optimized sections to the output
1284 // section. We need to postpone adding this until we've found a
1285 // section we can optimize so that the .eh_frame section in
1286 // crtbegin.o winds up at the start of the output section.
1287 if (!this->added_eh_frame_data_)
1289 os->add_output_section_data(this->eh_frame_data_);
1290 this->added_eh_frame_data_ = true;
1296 // We couldn't handle this .eh_frame section for some reason.
1297 // Add it as a normal section.
1298 bool saw_sections_clause = this->script_options_->saw_sections_clause();
1299 *off = os->add_input_section(this, object, shndx, ".eh_frame", shdr,
1300 reloc_shndx, saw_sections_clause);
1301 this->have_added_input_section_ = true;
1303 if ((orig_flags & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR))
1304 != (os->flags() & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR)))
1305 os->set_order(this->default_section_order(os, false));
1311 // Create and return the magic .eh_frame section. Create
1312 // .eh_frame_hdr also if appropriate. OBJECT is the object with the
1313 // input .eh_frame section; it may be NULL.
1316 Layout::make_eh_frame_section(const Relobj* object)
1318 // FIXME: On x86_64, this could use SHT_X86_64_UNWIND rather than
1320 Output_section* os = this->choose_output_section(object, ".eh_frame",
1321 elfcpp::SHT_PROGBITS,
1322 elfcpp::SHF_ALLOC, false,
1323 ORDER_EHFRAME, false);
1327 if (this->eh_frame_section_ == NULL)
1329 this->eh_frame_section_ = os;
1330 this->eh_frame_data_ = new Eh_frame();
1332 // For incremental linking, we do not optimize .eh_frame sections
1333 // or create a .eh_frame_hdr section.
1334 if (parameters->options().eh_frame_hdr() && !parameters->incremental())
1336 Output_section* hdr_os =
1337 this->choose_output_section(NULL, ".eh_frame_hdr",
1338 elfcpp::SHT_PROGBITS,
1339 elfcpp::SHF_ALLOC, false,
1340 ORDER_EHFRAME, false);
1344 Eh_frame_hdr* hdr_posd = new Eh_frame_hdr(os,
1345 this->eh_frame_data_);
1346 hdr_os->add_output_section_data(hdr_posd);
1348 hdr_os->set_after_input_sections();
1350 if (!this->script_options_->saw_phdrs_clause())
1352 Output_segment* hdr_oseg;
1353 hdr_oseg = this->make_output_segment(elfcpp::PT_GNU_EH_FRAME,
1355 hdr_oseg->add_output_section_to_nonload(hdr_os,
1359 this->eh_frame_data_->set_eh_frame_hdr(hdr_posd);
1367 // Add an exception frame for a PLT. This is called from target code.
1370 Layout::add_eh_frame_for_plt(Output_data* plt, const unsigned char* cie_data,
1371 size_t cie_length, const unsigned char* fde_data,
1374 if (parameters->incremental())
1376 // FIXME: Maybe this could work some day....
1379 Output_section* os = this->make_eh_frame_section(NULL);
1382 this->eh_frame_data_->add_ehframe_for_plt(plt, cie_data, cie_length,
1383 fde_data, fde_length);
1384 if (!this->added_eh_frame_data_)
1386 os->add_output_section_data(this->eh_frame_data_);
1387 this->added_eh_frame_data_ = true;
1391 // Scan a .debug_info or .debug_types section, and add summary
1392 // information to the .gdb_index section.
1394 template<int size, bool big_endian>
1396 Layout::add_to_gdb_index(bool is_type_unit,
1397 Sized_relobj<size, big_endian>* object,
1398 const unsigned char* symbols,
1401 unsigned int reloc_shndx,
1402 unsigned int reloc_type)
1404 if (this->gdb_index_data_ == NULL)
1406 Output_section* os = this->choose_output_section(NULL, ".gdb_index",
1407 elfcpp::SHT_PROGBITS, 0,
1408 false, ORDER_INVALID,
1413 this->gdb_index_data_ = new Gdb_index(os);
1414 os->add_output_section_data(this->gdb_index_data_);
1415 os->set_after_input_sections();
1418 this->gdb_index_data_->scan_debug_info(is_type_unit, object, symbols,
1419 symbols_size, shndx, reloc_shndx,
1423 // Add POSD to an output section using NAME, TYPE, and FLAGS. Return
1424 // the output section.
1427 Layout::add_output_section_data(const char* name, elfcpp::Elf_Word type,
1428 elfcpp::Elf_Xword flags,
1429 Output_section_data* posd,
1430 Output_section_order order, bool is_relro)
1432 Output_section* os = this->choose_output_section(NULL, name, type, flags,
1433 false, order, is_relro);
1435 os->add_output_section_data(posd);
1439 // Map section flags to segment flags.
1442 Layout::section_flags_to_segment(elfcpp::Elf_Xword flags)
1444 elfcpp::Elf_Word ret = elfcpp::PF_R;
1445 if ((flags & elfcpp::SHF_WRITE) != 0)
1446 ret |= elfcpp::PF_W;
1447 if ((flags & elfcpp::SHF_EXECINSTR) != 0)
1448 ret |= elfcpp::PF_X;
1452 // Make a new Output_section, and attach it to segments as
1453 // appropriate. ORDER is the order in which this section should
1454 // appear in the output segment. IS_RELRO is true if this is a relro
1455 // (read-only after relocations) section.
1458 Layout::make_output_section(const char* name, elfcpp::Elf_Word type,
1459 elfcpp::Elf_Xword flags,
1460 Output_section_order order, bool is_relro)
1463 if ((flags & elfcpp::SHF_ALLOC) == 0
1464 && strcmp(parameters->options().compress_debug_sections(), "none") != 0
1465 && is_compressible_debug_section(name))
1466 os = new Output_compressed_section(¶meters->options(), name, type,
1468 else if ((flags & elfcpp::SHF_ALLOC) == 0
1469 && parameters->options().strip_debug_non_line()
1470 && strcmp(".debug_abbrev", name) == 0)
1472 os = this->debug_abbrev_ = new Output_reduced_debug_abbrev_section(
1474 if (this->debug_info_)
1475 this->debug_info_->set_abbreviations(this->debug_abbrev_);
1477 else if ((flags & elfcpp::SHF_ALLOC) == 0
1478 && parameters->options().strip_debug_non_line()
1479 && strcmp(".debug_info", name) == 0)
1481 os = this->debug_info_ = new Output_reduced_debug_info_section(
1483 if (this->debug_abbrev_)
1484 this->debug_info_->set_abbreviations(this->debug_abbrev_);
1488 // Sometimes .init_array*, .preinit_array* and .fini_array* do
1489 // not have correct section types. Force them here.
1490 if (type == elfcpp::SHT_PROGBITS)
1492 if (is_prefix_of(".init_array", name))
1493 type = elfcpp::SHT_INIT_ARRAY;
1494 else if (is_prefix_of(".preinit_array", name))
1495 type = elfcpp::SHT_PREINIT_ARRAY;
1496 else if (is_prefix_of(".fini_array", name))
1497 type = elfcpp::SHT_FINI_ARRAY;
1500 // FIXME: const_cast is ugly.
1501 Target* target = const_cast<Target*>(¶meters->target());
1502 os = target->make_output_section(name, type, flags);
1505 // With -z relro, we have to recognize the special sections by name.
1506 // There is no other way.
1507 bool is_relro_local = false;
1508 if (!this->script_options_->saw_sections_clause()
1509 && parameters->options().relro()
1510 && (flags & elfcpp::SHF_ALLOC) != 0
1511 && (flags & elfcpp::SHF_WRITE) != 0)
1513 if (type == elfcpp::SHT_PROGBITS)
1515 if ((flags & elfcpp::SHF_TLS) != 0)
1517 else if (strcmp(name, ".data.rel.ro") == 0)
1519 else if (strcmp(name, ".data.rel.ro.local") == 0)
1522 is_relro_local = true;
1524 else if (strcmp(name, ".ctors") == 0
1525 || strcmp(name, ".dtors") == 0
1526 || strcmp(name, ".jcr") == 0)
1529 else if (type == elfcpp::SHT_INIT_ARRAY
1530 || type == elfcpp::SHT_FINI_ARRAY
1531 || type == elfcpp::SHT_PREINIT_ARRAY)
1538 if (order == ORDER_INVALID && (flags & elfcpp::SHF_ALLOC) != 0)
1539 order = this->default_section_order(os, is_relro_local);
1541 os->set_order(order);
1543 parameters->target().new_output_section(os);
1545 this->section_list_.push_back(os);
1547 // The GNU linker by default sorts some sections by priority, so we
1548 // do the same. We need to know that this might happen before we
1549 // attach any input sections.
1550 if (!this->script_options_->saw_sections_clause()
1551 && !parameters->options().relocatable()
1552 && (strcmp(name, ".init_array") == 0
1553 || strcmp(name, ".fini_array") == 0
1554 || (!parameters->options().ctors_in_init_array()
1555 && (strcmp(name, ".ctors") == 0
1556 || strcmp(name, ".dtors") == 0))))
1557 os->set_may_sort_attached_input_sections();
1559 // Check for .stab*str sections, as .stab* sections need to link to
1561 if (type == elfcpp::SHT_STRTAB
1562 && !this->have_stabstr_section_
1563 && strncmp(name, ".stab", 5) == 0
1564 && strcmp(name + strlen(name) - 3, "str") == 0)
1565 this->have_stabstr_section_ = true;
1567 // During a full incremental link, we add patch space to most
1568 // PROGBITS and NOBITS sections. Flag those that may be
1569 // arbitrarily padded.
1570 if ((type == elfcpp::SHT_PROGBITS || type == elfcpp::SHT_NOBITS)
1571 && order != ORDER_INTERP
1572 && order != ORDER_INIT
1573 && order != ORDER_PLT
1574 && order != ORDER_FINI
1575 && order != ORDER_RELRO_LAST
1576 && order != ORDER_NON_RELRO_FIRST
1577 && strcmp(name, ".eh_frame") != 0
1578 && strcmp(name, ".ctors") != 0
1579 && strcmp(name, ".dtors") != 0
1580 && strcmp(name, ".jcr") != 0)
1582 os->set_is_patch_space_allowed();
1584 // Certain sections require "holes" to be filled with
1585 // specific fill patterns. These fill patterns may have
1586 // a minimum size, so we must prevent allocations from the
1587 // free list that leave a hole smaller than the minimum.
1588 if (strcmp(name, ".debug_info") == 0)
1589 os->set_free_space_fill(new Output_fill_debug_info(false));
1590 else if (strcmp(name, ".debug_types") == 0)
1591 os->set_free_space_fill(new Output_fill_debug_info(true));
1592 else if (strcmp(name, ".debug_line") == 0)
1593 os->set_free_space_fill(new Output_fill_debug_line());
1596 // If we have already attached the sections to segments, then we
1597 // need to attach this one now. This happens for sections created
1598 // directly by the linker.
1599 if (this->sections_are_attached_)
1600 this->attach_section_to_segment(¶meters->target(), os);
1605 // Return the default order in which a section should be placed in an
1606 // output segment. This function captures a lot of the ideas in
1607 // ld/scripttempl/elf.sc in the GNU linker. Note that the order of a
1608 // linker created section is normally set when the section is created;
1609 // this function is used for input sections.
1611 Output_section_order
1612 Layout::default_section_order(Output_section* os, bool is_relro_local)
1614 gold_assert((os->flags() & elfcpp::SHF_ALLOC) != 0);
1615 bool is_write = (os->flags() & elfcpp::SHF_WRITE) != 0;
1616 bool is_execinstr = (os->flags() & elfcpp::SHF_EXECINSTR) != 0;
1617 bool is_bss = false;
1622 case elfcpp::SHT_PROGBITS:
1624 case elfcpp::SHT_NOBITS:
1627 case elfcpp::SHT_RELA:
1628 case elfcpp::SHT_REL:
1630 return ORDER_DYNAMIC_RELOCS;
1632 case elfcpp::SHT_HASH:
1633 case elfcpp::SHT_DYNAMIC:
1634 case elfcpp::SHT_SHLIB:
1635 case elfcpp::SHT_DYNSYM:
1636 case elfcpp::SHT_GNU_HASH:
1637 case elfcpp::SHT_GNU_verdef:
1638 case elfcpp::SHT_GNU_verneed:
1639 case elfcpp::SHT_GNU_versym:
1641 return ORDER_DYNAMIC_LINKER;
1643 case elfcpp::SHT_NOTE:
1644 return is_write ? ORDER_RW_NOTE : ORDER_RO_NOTE;
1647 if ((os->flags() & elfcpp::SHF_TLS) != 0)
1648 return is_bss ? ORDER_TLS_BSS : ORDER_TLS_DATA;
1650 if (!is_bss && !is_write)
1654 if (strcmp(os->name(), ".init") == 0)
1656 else if (strcmp(os->name(), ".fini") == 0)
1659 return is_execinstr ? ORDER_TEXT : ORDER_READONLY;
1663 return is_relro_local ? ORDER_RELRO_LOCAL : ORDER_RELRO;
1665 if (os->is_small_section())
1666 return is_bss ? ORDER_SMALL_BSS : ORDER_SMALL_DATA;
1667 if (os->is_large_section())
1668 return is_bss ? ORDER_LARGE_BSS : ORDER_LARGE_DATA;
1670 return is_bss ? ORDER_BSS : ORDER_DATA;
1673 // Attach output sections to segments. This is called after we have
1674 // seen all the input sections.
1677 Layout::attach_sections_to_segments(const Target* target)
1679 for (Section_list::iterator p = this->section_list_.begin();
1680 p != this->section_list_.end();
1682 this->attach_section_to_segment(target, *p);
1684 this->sections_are_attached_ = true;
1687 // Attach an output section to a segment.
1690 Layout::attach_section_to_segment(const Target* target, Output_section* os)
1692 if ((os->flags() & elfcpp::SHF_ALLOC) == 0)
1693 this->unattached_section_list_.push_back(os);
1695 this->attach_allocated_section_to_segment(target, os);
1698 // Attach an allocated output section to a segment.
1701 Layout::attach_allocated_section_to_segment(const Target* target,
1704 elfcpp::Elf_Xword flags = os->flags();
1705 gold_assert((flags & elfcpp::SHF_ALLOC) != 0);
1707 if (parameters->options().relocatable())
1710 // If we have a SECTIONS clause, we can't handle the attachment to
1711 // segments until after we've seen all the sections.
1712 if (this->script_options_->saw_sections_clause())
1715 gold_assert(!this->script_options_->saw_phdrs_clause());
1717 // This output section goes into a PT_LOAD segment.
1719 elfcpp::Elf_Word seg_flags = Layout::section_flags_to_segment(flags);
1721 // Check for --section-start.
1723 bool is_address_set = parameters->options().section_start(os->name(), &addr);
1725 // In general the only thing we really care about for PT_LOAD
1726 // segments is whether or not they are writable or executable,
1727 // so that is how we search for them.
1728 // Large data sections also go into their own PT_LOAD segment.
1729 // People who need segments sorted on some other basis will
1730 // have to use a linker script.
1732 Segment_list::const_iterator p;
1733 for (p = this->segment_list_.begin();
1734 p != this->segment_list_.end();
1737 if ((*p)->type() != elfcpp::PT_LOAD)
1739 if (!parameters->options().omagic()
1740 && ((*p)->flags() & elfcpp::PF_W) != (seg_flags & elfcpp::PF_W))
1742 if ((target->isolate_execinstr() || parameters->options().rosegment())
1743 && ((*p)->flags() & elfcpp::PF_X) != (seg_flags & elfcpp::PF_X))
1745 // If -Tbss was specified, we need to separate the data and BSS
1747 if (parameters->options().user_set_Tbss())
1749 if ((os->type() == elfcpp::SHT_NOBITS)
1750 == (*p)->has_any_data_sections())
1753 if (os->is_large_data_section() && !(*p)->is_large_data_segment())
1758 if ((*p)->are_addresses_set())
1761 (*p)->add_initial_output_data(os);
1762 (*p)->update_flags_for_output_section(seg_flags);
1763 (*p)->set_addresses(addr, addr);
1767 (*p)->add_output_section_to_load(this, os, seg_flags);
1771 if (p == this->segment_list_.end())
1773 Output_segment* oseg = this->make_output_segment(elfcpp::PT_LOAD,
1775 if (os->is_large_data_section())
1776 oseg->set_is_large_data_segment();
1777 oseg->add_output_section_to_load(this, os, seg_flags);
1779 oseg->set_addresses(addr, addr);
1782 // If we see a loadable SHT_NOTE section, we create a PT_NOTE
1784 if (os->type() == elfcpp::SHT_NOTE)
1786 // See if we already have an equivalent PT_NOTE segment.
1787 for (p = this->segment_list_.begin();
1788 p != segment_list_.end();
1791 if ((*p)->type() == elfcpp::PT_NOTE
1792 && (((*p)->flags() & elfcpp::PF_W)
1793 == (seg_flags & elfcpp::PF_W)))
1795 (*p)->add_output_section_to_nonload(os, seg_flags);
1800 if (p == this->segment_list_.end())
1802 Output_segment* oseg = this->make_output_segment(elfcpp::PT_NOTE,
1804 oseg->add_output_section_to_nonload(os, seg_flags);
1808 // If we see a loadable SHF_TLS section, we create a PT_TLS
1809 // segment. There can only be one such segment.
1810 if ((flags & elfcpp::SHF_TLS) != 0)
1812 if (this->tls_segment_ == NULL)
1813 this->make_output_segment(elfcpp::PT_TLS, seg_flags);
1814 this->tls_segment_->add_output_section_to_nonload(os, seg_flags);
1817 // If -z relro is in effect, and we see a relro section, we create a
1818 // PT_GNU_RELRO segment. There can only be one such segment.
1819 if (os->is_relro() && parameters->options().relro())
1821 gold_assert(seg_flags == (elfcpp::PF_R | elfcpp::PF_W));
1822 if (this->relro_segment_ == NULL)
1823 this->make_output_segment(elfcpp::PT_GNU_RELRO, seg_flags);
1824 this->relro_segment_->add_output_section_to_nonload(os, seg_flags);
1827 // If we see a section named .interp, put it into a PT_INTERP
1828 // segment. This seems broken to me, but this is what GNU ld does,
1829 // and glibc expects it.
1830 if (strcmp(os->name(), ".interp") == 0
1831 && !this->script_options_->saw_phdrs_clause())
1833 if (this->interp_segment_ == NULL)
1834 this->make_output_segment(elfcpp::PT_INTERP, seg_flags);
1836 gold_warning(_("multiple '.interp' sections in input files "
1837 "may cause confusing PT_INTERP segment"));
1838 this->interp_segment_->add_output_section_to_nonload(os, seg_flags);
1842 // Make an output section for a script.
1845 Layout::make_output_section_for_script(
1847 Script_sections::Section_type section_type)
1849 name = this->namepool_.add(name, false, NULL);
1850 elfcpp::Elf_Xword sh_flags = elfcpp::SHF_ALLOC;
1851 if (section_type == Script_sections::ST_NOLOAD)
1853 Output_section* os = this->make_output_section(name, elfcpp::SHT_PROGBITS,
1854 sh_flags, ORDER_INVALID,
1856 os->set_found_in_sections_clause();
1857 if (section_type == Script_sections::ST_NOLOAD)
1858 os->set_is_noload();
1862 // Return the number of segments we expect to see.
1865 Layout::expected_segment_count() const
1867 size_t ret = this->segment_list_.size();
1869 // If we didn't see a SECTIONS clause in a linker script, we should
1870 // already have the complete list of segments. Otherwise we ask the
1871 // SECTIONS clause how many segments it expects, and add in the ones
1872 // we already have (PT_GNU_STACK, PT_GNU_EH_FRAME, etc.)
1874 if (!this->script_options_->saw_sections_clause())
1878 const Script_sections* ss = this->script_options_->script_sections();
1879 return ret + ss->expected_segment_count(this);
1883 // Handle the .note.GNU-stack section at layout time. SEEN_GNU_STACK
1884 // is whether we saw a .note.GNU-stack section in the object file.
1885 // GNU_STACK_FLAGS is the section flags. The flags give the
1886 // protection required for stack memory. We record this in an
1887 // executable as a PT_GNU_STACK segment. If an object file does not
1888 // have a .note.GNU-stack segment, we must assume that it is an old
1889 // object. On some targets that will force an executable stack.
1892 Layout::layout_gnu_stack(bool seen_gnu_stack, uint64_t gnu_stack_flags,
1895 if (!seen_gnu_stack)
1897 this->input_without_gnu_stack_note_ = true;
1898 if (parameters->options().warn_execstack()
1899 && parameters->target().is_default_stack_executable())
1900 gold_warning(_("%s: missing .note.GNU-stack section"
1901 " implies executable stack"),
1902 obj->name().c_str());
1906 this->input_with_gnu_stack_note_ = true;
1907 if ((gnu_stack_flags & elfcpp::SHF_EXECINSTR) != 0)
1909 this->input_requires_executable_stack_ = true;
1910 if (parameters->options().warn_execstack()
1911 || parameters->options().is_stack_executable())
1912 gold_warning(_("%s: requires executable stack"),
1913 obj->name().c_str());
1918 // Create automatic note sections.
1921 Layout::create_notes()
1923 this->create_gold_note();
1924 this->create_executable_stack_info();
1925 this->create_build_id();
1928 // Create the dynamic sections which are needed before we read the
1932 Layout::create_initial_dynamic_sections(Symbol_table* symtab)
1934 if (parameters->doing_static_link())
1937 this->dynamic_section_ = this->choose_output_section(NULL, ".dynamic",
1938 elfcpp::SHT_DYNAMIC,
1940 | elfcpp::SHF_WRITE),
1944 // A linker script may discard .dynamic, so check for NULL.
1945 if (this->dynamic_section_ != NULL)
1947 this->dynamic_symbol_ =
1948 symtab->define_in_output_data("_DYNAMIC", NULL,
1949 Symbol_table::PREDEFINED,
1950 this->dynamic_section_, 0, 0,
1951 elfcpp::STT_OBJECT, elfcpp::STB_LOCAL,
1952 elfcpp::STV_HIDDEN, 0, false, false);
1954 this->dynamic_data_ = new Output_data_dynamic(&this->dynpool_);
1956 this->dynamic_section_->add_output_section_data(this->dynamic_data_);
1960 // For each output section whose name can be represented as C symbol,
1961 // define __start and __stop symbols for the section. This is a GNU
1965 Layout::define_section_symbols(Symbol_table* symtab)
1967 for (Section_list::const_iterator p = this->section_list_.begin();
1968 p != this->section_list_.end();
1971 const char* const name = (*p)->name();
1972 if (is_cident(name))
1974 const std::string name_string(name);
1975 const std::string start_name(cident_section_start_prefix
1977 const std::string stop_name(cident_section_stop_prefix
1980 symtab->define_in_output_data(start_name.c_str(),
1982 Symbol_table::PREDEFINED,
1988 elfcpp::STV_DEFAULT,
1990 false, // offset_is_from_end
1991 true); // only_if_ref
1993 symtab->define_in_output_data(stop_name.c_str(),
1995 Symbol_table::PREDEFINED,
2001 elfcpp::STV_DEFAULT,
2003 true, // offset_is_from_end
2004 true); // only_if_ref
2009 // Define symbols for group signatures.
2012 Layout::define_group_signatures(Symbol_table* symtab)
2014 for (Group_signatures::iterator p = this->group_signatures_.begin();
2015 p != this->group_signatures_.end();
2018 Symbol* sym = symtab->lookup(p->signature, NULL);
2020 p->section->set_info_symndx(sym);
2023 // Force the name of the group section to the group
2024 // signature, and use the group's section symbol as the
2025 // signature symbol.
2026 if (strcmp(p->section->name(), p->signature) != 0)
2028 const char* name = this->namepool_.add(p->signature,
2030 p->section->set_name(name);
2032 p->section->set_needs_symtab_index();
2033 p->section->set_info_section_symndx(p->section);
2037 this->group_signatures_.clear();
2040 // Find the first read-only PT_LOAD segment, creating one if
2044 Layout::find_first_load_seg(const Target* target)
2046 Output_segment* best = NULL;
2047 for (Segment_list::const_iterator p = this->segment_list_.begin();
2048 p != this->segment_list_.end();
2051 if ((*p)->type() == elfcpp::PT_LOAD
2052 && ((*p)->flags() & elfcpp::PF_R) != 0
2053 && (parameters->options().omagic()
2054 || ((*p)->flags() & elfcpp::PF_W) == 0)
2055 && (!target->isolate_execinstr()
2056 || ((*p)->flags() & elfcpp::PF_X) == 0))
2058 if (best == NULL || this->segment_precedes(*p, best))
2065 gold_assert(!this->script_options_->saw_phdrs_clause());
2067 Output_segment* load_seg = this->make_output_segment(elfcpp::PT_LOAD,
2072 // Save states of all current output segments. Store saved states
2073 // in SEGMENT_STATES.
2076 Layout::save_segments(Segment_states* segment_states)
2078 for (Segment_list::const_iterator p = this->segment_list_.begin();
2079 p != this->segment_list_.end();
2082 Output_segment* segment = *p;
2084 Output_segment* copy = new Output_segment(*segment);
2085 (*segment_states)[segment] = copy;
2089 // Restore states of output segments and delete any segment not found in
2093 Layout::restore_segments(const Segment_states* segment_states)
2095 // Go through the segment list and remove any segment added in the
2097 this->tls_segment_ = NULL;
2098 this->relro_segment_ = NULL;
2099 Segment_list::iterator list_iter = this->segment_list_.begin();
2100 while (list_iter != this->segment_list_.end())
2102 Output_segment* segment = *list_iter;
2103 Segment_states::const_iterator states_iter =
2104 segment_states->find(segment);
2105 if (states_iter != segment_states->end())
2107 const Output_segment* copy = states_iter->second;
2108 // Shallow copy to restore states.
2111 // Also fix up TLS and RELRO segment pointers as appropriate.
2112 if (segment->type() == elfcpp::PT_TLS)
2113 this->tls_segment_ = segment;
2114 else if (segment->type() == elfcpp::PT_GNU_RELRO)
2115 this->relro_segment_ = segment;
2121 list_iter = this->segment_list_.erase(list_iter);
2122 // This is a segment created during section layout. It should be
2123 // safe to remove it since we should have removed all pointers to it.
2129 // Clean up after relaxation so that sections can be laid out again.
2132 Layout::clean_up_after_relaxation()
2134 // Restore the segments to point state just prior to the relaxation loop.
2135 Script_sections* script_section = this->script_options_->script_sections();
2136 script_section->release_segments();
2137 this->restore_segments(this->segment_states_);
2139 // Reset section addresses and file offsets
2140 for (Section_list::iterator p = this->section_list_.begin();
2141 p != this->section_list_.end();
2144 (*p)->restore_states();
2146 // If an input section changes size because of relaxation,
2147 // we need to adjust the section offsets of all input sections.
2148 // after such a section.
2149 if ((*p)->section_offsets_need_adjustment())
2150 (*p)->adjust_section_offsets();
2152 (*p)->reset_address_and_file_offset();
2155 // Reset special output object address and file offsets.
2156 for (Data_list::iterator p = this->special_output_list_.begin();
2157 p != this->special_output_list_.end();
2159 (*p)->reset_address_and_file_offset();
2161 // A linker script may have created some output section data objects.
2162 // They are useless now.
2163 for (Output_section_data_list::const_iterator p =
2164 this->script_output_section_data_list_.begin();
2165 p != this->script_output_section_data_list_.end();
2168 this->script_output_section_data_list_.clear();
2171 // Prepare for relaxation.
2174 Layout::prepare_for_relaxation()
2176 // Create an relaxation debug check if in debugging mode.
2177 if (is_debugging_enabled(DEBUG_RELAXATION))
2178 this->relaxation_debug_check_ = new Relaxation_debug_check();
2180 // Save segment states.
2181 this->segment_states_ = new Segment_states();
2182 this->save_segments(this->segment_states_);
2184 for(Section_list::const_iterator p = this->section_list_.begin();
2185 p != this->section_list_.end();
2187 (*p)->save_states();
2189 if (is_debugging_enabled(DEBUG_RELAXATION))
2190 this->relaxation_debug_check_->check_output_data_for_reset_values(
2191 this->section_list_, this->special_output_list_);
2193 // Also enable recording of output section data from scripts.
2194 this->record_output_section_data_from_script_ = true;
2197 // Relaxation loop body: If target has no relaxation, this runs only once
2198 // Otherwise, the target relaxation hook is called at the end of
2199 // each iteration. If the hook returns true, it means re-layout of
2200 // section is required.
2202 // The number of segments created by a linking script without a PHDRS
2203 // clause may be affected by section sizes and alignments. There is
2204 // a remote chance that relaxation causes different number of PT_LOAD
2205 // segments are created and sections are attached to different segments.
2206 // Therefore, we always throw away all segments created during section
2207 // layout. In order to be able to restart the section layout, we keep
2208 // a copy of the segment list right before the relaxation loop and use
2209 // that to restore the segments.
2211 // PASS is the current relaxation pass number.
2212 // SYMTAB is a symbol table.
2213 // PLOAD_SEG is the address of a pointer for the load segment.
2214 // PHDR_SEG is a pointer to the PHDR segment.
2215 // SEGMENT_HEADERS points to the output segment header.
2216 // FILE_HEADER points to the output file header.
2217 // PSHNDX is the address to store the output section index.
2220 Layout::relaxation_loop_body(
2223 Symbol_table* symtab,
2224 Output_segment** pload_seg,
2225 Output_segment* phdr_seg,
2226 Output_segment_headers* segment_headers,
2227 Output_file_header* file_header,
2228 unsigned int* pshndx)
2230 // If this is not the first iteration, we need to clean up after
2231 // relaxation so that we can lay out the sections again.
2233 this->clean_up_after_relaxation();
2235 // If there is a SECTIONS clause, put all the input sections into
2236 // the required order.
2237 Output_segment* load_seg;
2238 if (this->script_options_->saw_sections_clause())
2239 load_seg = this->set_section_addresses_from_script(symtab);
2240 else if (parameters->options().relocatable())
2243 load_seg = this->find_first_load_seg(target);
2245 if (parameters->options().oformat_enum()
2246 != General_options::OBJECT_FORMAT_ELF)
2249 // If the user set the address of the text segment, that may not be
2250 // compatible with putting the segment headers and file headers into
2252 if (parameters->options().user_set_Ttext()
2253 && parameters->options().Ttext() % target->common_pagesize() != 0)
2259 gold_assert(phdr_seg == NULL
2261 || this->script_options_->saw_sections_clause());
2263 // If the address of the load segment we found has been set by
2264 // --section-start rather than by a script, then adjust the VMA and
2265 // LMA downward if possible to include the file and section headers.
2266 uint64_t header_gap = 0;
2267 if (load_seg != NULL
2268 && load_seg->are_addresses_set()
2269 && !this->script_options_->saw_sections_clause()
2270 && !parameters->options().relocatable())
2272 file_header->finalize_data_size();
2273 segment_headers->finalize_data_size();
2274 size_t sizeof_headers = (file_header->data_size()
2275 + segment_headers->data_size());
2276 const uint64_t abi_pagesize = target->abi_pagesize();
2277 uint64_t hdr_paddr = load_seg->paddr() - sizeof_headers;
2278 hdr_paddr &= ~(abi_pagesize - 1);
2279 uint64_t subtract = load_seg->paddr() - hdr_paddr;
2280 if (load_seg->paddr() < subtract || load_seg->vaddr() < subtract)
2284 load_seg->set_addresses(load_seg->vaddr() - subtract,
2285 load_seg->paddr() - subtract);
2286 header_gap = subtract - sizeof_headers;
2290 // Lay out the segment headers.
2291 if (!parameters->options().relocatable())
2293 gold_assert(segment_headers != NULL);
2294 if (header_gap != 0 && load_seg != NULL)
2296 Output_data_zero_fill* z = new Output_data_zero_fill(header_gap, 1);
2297 load_seg->add_initial_output_data(z);
2299 if (load_seg != NULL)
2300 load_seg->add_initial_output_data(segment_headers);
2301 if (phdr_seg != NULL)
2302 phdr_seg->add_initial_output_data(segment_headers);
2305 // Lay out the file header.
2306 if (load_seg != NULL)
2307 load_seg->add_initial_output_data(file_header);
2309 if (this->script_options_->saw_phdrs_clause()
2310 && !parameters->options().relocatable())
2312 // Support use of FILEHDRS and PHDRS attachments in a PHDRS
2313 // clause in a linker script.
2314 Script_sections* ss = this->script_options_->script_sections();
2315 ss->put_headers_in_phdrs(file_header, segment_headers);
2318 // We set the output section indexes in set_segment_offsets and
2319 // set_section_indexes.
2322 // Set the file offsets of all the segments, and all the sections
2325 if (!parameters->options().relocatable())
2326 off = this->set_segment_offsets(target, load_seg, pshndx);
2328 off = this->set_relocatable_section_offsets(file_header, pshndx);
2330 // Verify that the dummy relaxation does not change anything.
2331 if (is_debugging_enabled(DEBUG_RELAXATION))
2334 this->relaxation_debug_check_->read_sections(this->section_list_);
2336 this->relaxation_debug_check_->verify_sections(this->section_list_);
2339 *pload_seg = load_seg;
2343 // Search the list of patterns and find the postion of the given section
2344 // name in the output section. If the section name matches a glob
2345 // pattern and a non-glob name, then the non-glob position takes
2346 // precedence. Return 0 if no match is found.
2349 Layout::find_section_order_index(const std::string& section_name)
2351 Unordered_map<std::string, unsigned int>::iterator map_it;
2352 map_it = this->input_section_position_.find(section_name);
2353 if (map_it != this->input_section_position_.end())
2354 return map_it->second;
2356 // Absolute match failed. Linear search the glob patterns.
2357 std::vector<std::string>::iterator it;
2358 for (it = this->input_section_glob_.begin();
2359 it != this->input_section_glob_.end();
2362 if (fnmatch((*it).c_str(), section_name.c_str(), FNM_NOESCAPE) == 0)
2364 map_it = this->input_section_position_.find(*it);
2365 gold_assert(map_it != this->input_section_position_.end());
2366 return map_it->second;
2372 // Read the sequence of input sections from the file specified with
2373 // option --section-ordering-file.
2376 Layout::read_layout_from_file()
2378 const char* filename = parameters->options().section_ordering_file();
2384 gold_fatal(_("unable to open --section-ordering-file file %s: %s"),
2385 filename, strerror(errno));
2387 std::getline(in, line); // this chops off the trailing \n, if any
2388 unsigned int position = 1;
2389 this->set_section_ordering_specified();
2393 if (!line.empty() && line[line.length() - 1] == '\r') // Windows
2394 line.resize(line.length() - 1);
2395 // Ignore comments, beginning with '#'
2398 std::getline(in, line);
2401 this->input_section_position_[line] = position;
2402 // Store all glob patterns in a vector.
2403 if (is_wildcard_string(line.c_str()))
2404 this->input_section_glob_.push_back(line);
2406 std::getline(in, line);
2410 // Finalize the layout. When this is called, we have created all the
2411 // output sections and all the output segments which are based on
2412 // input sections. We have several things to do, and we have to do
2413 // them in the right order, so that we get the right results correctly
2416 // 1) Finalize the list of output segments and create the segment
2419 // 2) Finalize the dynamic symbol table and associated sections.
2421 // 3) Determine the final file offset of all the output segments.
2423 // 4) Determine the final file offset of all the SHF_ALLOC output
2426 // 5) Create the symbol table sections and the section name table
2429 // 6) Finalize the symbol table: set symbol values to their final
2430 // value and make a final determination of which symbols are going
2431 // into the output symbol table.
2433 // 7) Create the section table header.
2435 // 8) Determine the final file offset of all the output sections which
2436 // are not SHF_ALLOC, including the section table header.
2438 // 9) Finalize the ELF file header.
2440 // This function returns the size of the output file.
2443 Layout::finalize(const Input_objects* input_objects, Symbol_table* symtab,
2444 Target* target, const Task* task)
2446 target->finalize_sections(this, input_objects, symtab);
2448 this->count_local_symbols(task, input_objects);
2450 this->link_stabs_sections();
2452 Output_segment* phdr_seg = NULL;
2453 if (!parameters->options().relocatable() && !parameters->doing_static_link())
2455 // There was a dynamic object in the link. We need to create
2456 // some information for the dynamic linker.
2458 // Create the PT_PHDR segment which will hold the program
2460 if (!this->script_options_->saw_phdrs_clause())
2461 phdr_seg = this->make_output_segment(elfcpp::PT_PHDR, elfcpp::PF_R);
2463 // Create the dynamic symbol table, including the hash table.
2464 Output_section* dynstr;
2465 std::vector<Symbol*> dynamic_symbols;
2466 unsigned int local_dynamic_count;
2467 Versions versions(*this->script_options()->version_script_info(),
2469 this->create_dynamic_symtab(input_objects, symtab, &dynstr,
2470 &local_dynamic_count, &dynamic_symbols,
2473 // Create the .interp section to hold the name of the
2474 // interpreter, and put it in a PT_INTERP segment. Don't do it
2475 // if we saw a .interp section in an input file.
2476 if ((!parameters->options().shared()
2477 || parameters->options().dynamic_linker() != NULL)
2478 && this->interp_segment_ == NULL)
2479 this->create_interp(target);
2481 // Finish the .dynamic section to hold the dynamic data, and put
2482 // it in a PT_DYNAMIC segment.
2483 this->finish_dynamic_section(input_objects, symtab);
2485 // We should have added everything we need to the dynamic string
2487 this->dynpool_.set_string_offsets();
2489 // Create the version sections. We can't do this until the
2490 // dynamic string table is complete.
2491 this->create_version_sections(&versions, symtab, local_dynamic_count,
2492 dynamic_symbols, dynstr);
2494 // Set the size of the _DYNAMIC symbol. We can't do this until
2495 // after we call create_version_sections.
2496 this->set_dynamic_symbol_size(symtab);
2499 // Create segment headers.
2500 Output_segment_headers* segment_headers =
2501 (parameters->options().relocatable()
2503 : new Output_segment_headers(this->segment_list_));
2505 // Lay out the file header.
2506 Output_file_header* file_header = new Output_file_header(target, symtab,
2509 this->special_output_list_.push_back(file_header);
2510 if (segment_headers != NULL)
2511 this->special_output_list_.push_back(segment_headers);
2513 // Find approriate places for orphan output sections if we are using
2515 if (this->script_options_->saw_sections_clause())
2516 this->place_orphan_sections_in_script();
2518 Output_segment* load_seg;
2523 // Take a snapshot of the section layout as needed.
2524 if (target->may_relax())
2525 this->prepare_for_relaxation();
2527 // Run the relaxation loop to lay out sections.
2530 off = this->relaxation_loop_body(pass, target, symtab, &load_seg,
2531 phdr_seg, segment_headers, file_header,
2535 while (target->may_relax()
2536 && target->relax(pass, input_objects, symtab, this, task));
2538 // If there is a load segment that contains the file and program headers,
2539 // provide a symbol __ehdr_start pointing there.
2540 // A program can use this to examine itself robustly.
2541 if (load_seg != NULL)
2542 symtab->define_in_output_segment("__ehdr_start", NULL,
2543 Symbol_table::PREDEFINED, load_seg, 0, 0,
2544 elfcpp::STT_NOTYPE, elfcpp::STB_GLOBAL,
2545 elfcpp::STV_DEFAULT, 0,
2546 Symbol::SEGMENT_START, true);
2548 // Set the file offsets of all the non-data sections we've seen so
2549 // far which don't have to wait for the input sections. We need
2550 // this in order to finalize local symbols in non-allocated
2552 off = this->set_section_offsets(off, BEFORE_INPUT_SECTIONS_PASS);
2554 // Set the section indexes of all unallocated sections seen so far,
2555 // in case any of them are somehow referenced by a symbol.
2556 shndx = this->set_section_indexes(shndx);
2558 // Create the symbol table sections.
2559 this->create_symtab_sections(input_objects, symtab, shndx, &off);
2560 if (!parameters->doing_static_link())
2561 this->assign_local_dynsym_offsets(input_objects);
2563 // Process any symbol assignments from a linker script. This must
2564 // be called after the symbol table has been finalized.
2565 this->script_options_->finalize_symbols(symtab, this);
2567 // Create the incremental inputs sections.
2568 if (this->incremental_inputs_)
2570 this->incremental_inputs_->finalize();
2571 this->create_incremental_info_sections(symtab);
2574 // Create the .shstrtab section.
2575 Output_section* shstrtab_section = this->create_shstrtab();
2577 // Set the file offsets of the rest of the non-data sections which
2578 // don't have to wait for the input sections.
2579 off = this->set_section_offsets(off, BEFORE_INPUT_SECTIONS_PASS);
2581 // Now that all sections have been created, set the section indexes
2582 // for any sections which haven't been done yet.
2583 shndx = this->set_section_indexes(shndx);
2585 // Create the section table header.
2586 this->create_shdrs(shstrtab_section, &off);
2588 // If there are no sections which require postprocessing, we can
2589 // handle the section names now, and avoid a resize later.
2590 if (!this->any_postprocessing_sections_)
2592 off = this->set_section_offsets(off,
2593 POSTPROCESSING_SECTIONS_PASS);
2595 this->set_section_offsets(off,
2596 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS);
2599 file_header->set_section_info(this->section_headers_, shstrtab_section);
2601 // Now we know exactly where everything goes in the output file
2602 // (except for non-allocated sections which require postprocessing).
2603 Output_data::layout_complete();
2605 this->output_file_size_ = off;
2610 // Create a note header following the format defined in the ELF ABI.
2611 // NAME is the name, NOTE_TYPE is the type, SECTION_NAME is the name
2612 // of the section to create, DESCSZ is the size of the descriptor.
2613 // ALLOCATE is true if the section should be allocated in memory.
2614 // This returns the new note section. It sets *TRAILING_PADDING to
2615 // the number of trailing zero bytes required.
2618 Layout::create_note(const char* name, int note_type,
2619 const char* section_name, size_t descsz,
2620 bool allocate, size_t* trailing_padding)
2622 // Authorities all agree that the values in a .note field should
2623 // be aligned on 4-byte boundaries for 32-bit binaries. However,
2624 // they differ on what the alignment is for 64-bit binaries.
2625 // The GABI says unambiguously they take 8-byte alignment:
2626 // http://sco.com/developers/gabi/latest/ch5.pheader.html#note_section
2627 // Other documentation says alignment should always be 4 bytes:
2628 // http://www.netbsd.org/docs/kernel/elf-notes.html#note-format
2629 // GNU ld and GNU readelf both support the latter (at least as of
2630 // version 2.16.91), and glibc always generates the latter for
2631 // .note.ABI-tag (as of version 1.6), so that's the one we go with
2633 #ifdef GABI_FORMAT_FOR_DOTNOTE_SECTION // This is not defined by default.
2634 const int size = parameters->target().get_size();
2636 const int size = 32;
2639 // The contents of the .note section.
2640 size_t namesz = strlen(name) + 1;
2641 size_t aligned_namesz = align_address(namesz, size / 8);
2642 size_t aligned_descsz = align_address(descsz, size / 8);
2644 size_t notehdrsz = 3 * (size / 8) + aligned_namesz;
2646 unsigned char* buffer = new unsigned char[notehdrsz];
2647 memset(buffer, 0, notehdrsz);
2649 bool is_big_endian = parameters->target().is_big_endian();
2655 elfcpp::Swap<32, false>::writeval(buffer, namesz);
2656 elfcpp::Swap<32, false>::writeval(buffer + 4, descsz);
2657 elfcpp::Swap<32, false>::writeval(buffer + 8, note_type);
2661 elfcpp::Swap<32, true>::writeval(buffer, namesz);
2662 elfcpp::Swap<32, true>::writeval(buffer + 4, descsz);
2663 elfcpp::Swap<32, true>::writeval(buffer + 8, note_type);
2666 else if (size == 64)
2670 elfcpp::Swap<64, false>::writeval(buffer, namesz);
2671 elfcpp::Swap<64, false>::writeval(buffer + 8, descsz);
2672 elfcpp::Swap<64, false>::writeval(buffer + 16, note_type);
2676 elfcpp::Swap<64, true>::writeval(buffer, namesz);
2677 elfcpp::Swap<64, true>::writeval(buffer + 8, descsz);
2678 elfcpp::Swap<64, true>::writeval(buffer + 16, note_type);
2684 memcpy(buffer + 3 * (size / 8), name, namesz);
2686 elfcpp::Elf_Xword flags = 0;
2687 Output_section_order order = ORDER_INVALID;
2690 flags = elfcpp::SHF_ALLOC;
2691 order = ORDER_RO_NOTE;
2693 Output_section* os = this->choose_output_section(NULL, section_name,
2695 flags, false, order, false);
2699 Output_section_data* posd = new Output_data_const_buffer(buffer, notehdrsz,
2702 os->add_output_section_data(posd);
2704 *trailing_padding = aligned_descsz - descsz;
2709 // For an executable or shared library, create a note to record the
2710 // version of gold used to create the binary.
2713 Layout::create_gold_note()
2715 if (parameters->options().relocatable()
2716 || parameters->incremental_update())
2719 std::string desc = std::string("gold ") + gold::get_version_string();
2721 size_t trailing_padding;
2722 Output_section* os = this->create_note("GNU", elfcpp::NT_GNU_GOLD_VERSION,
2723 ".note.gnu.gold-version", desc.size(),
2724 false, &trailing_padding);
2728 Output_section_data* posd = new Output_data_const(desc, 4);
2729 os->add_output_section_data(posd);
2731 if (trailing_padding > 0)
2733 posd = new Output_data_zero_fill(trailing_padding, 0);
2734 os->add_output_section_data(posd);
2738 // Record whether the stack should be executable. This can be set
2739 // from the command line using the -z execstack or -z noexecstack
2740 // options. Otherwise, if any input file has a .note.GNU-stack
2741 // section with the SHF_EXECINSTR flag set, the stack should be
2742 // executable. Otherwise, if at least one input file a
2743 // .note.GNU-stack section, and some input file has no .note.GNU-stack
2744 // section, we use the target default for whether the stack should be
2745 // executable. Otherwise, we don't generate a stack note. When
2746 // generating a object file, we create a .note.GNU-stack section with
2747 // the appropriate marking. When generating an executable or shared
2748 // library, we create a PT_GNU_STACK segment.
2751 Layout::create_executable_stack_info()
2753 bool is_stack_executable;
2754 if (parameters->options().is_execstack_set())
2755 is_stack_executable = parameters->options().is_stack_executable();
2756 else if (!this->input_with_gnu_stack_note_)
2760 if (this->input_requires_executable_stack_)
2761 is_stack_executable = true;
2762 else if (this->input_without_gnu_stack_note_)
2763 is_stack_executable =
2764 parameters->target().is_default_stack_executable();
2766 is_stack_executable = false;
2769 if (parameters->options().relocatable())
2771 const char* name = this->namepool_.add(".note.GNU-stack", false, NULL);
2772 elfcpp::Elf_Xword flags = 0;
2773 if (is_stack_executable)
2774 flags |= elfcpp::SHF_EXECINSTR;
2775 this->make_output_section(name, elfcpp::SHT_PROGBITS, flags,
2776 ORDER_INVALID, false);
2780 if (this->script_options_->saw_phdrs_clause())
2782 int flags = elfcpp::PF_R | elfcpp::PF_W;
2783 if (is_stack_executable)
2784 flags |= elfcpp::PF_X;
2785 this->make_output_segment(elfcpp::PT_GNU_STACK, flags);
2789 // If --build-id was used, set up the build ID note.
2792 Layout::create_build_id()
2794 if (!parameters->options().user_set_build_id())
2797 const char* style = parameters->options().build_id();
2798 if (strcmp(style, "none") == 0)
2801 // Set DESCSZ to the size of the note descriptor. When possible,
2802 // set DESC to the note descriptor contents.
2805 if (strcmp(style, "md5") == 0)
2807 else if (strcmp(style, "sha1") == 0)
2809 else if (strcmp(style, "uuid") == 0)
2811 const size_t uuidsz = 128 / 8;
2813 char buffer[uuidsz];
2814 memset(buffer, 0, uuidsz);
2816 int descriptor = open_descriptor(-1, "/dev/urandom", O_RDONLY);
2818 gold_error(_("--build-id=uuid failed: could not open /dev/urandom: %s"),
2822 ssize_t got = ::read(descriptor, buffer, uuidsz);
2823 release_descriptor(descriptor, true);
2825 gold_error(_("/dev/urandom: read failed: %s"), strerror(errno));
2826 else if (static_cast<size_t>(got) != uuidsz)
2827 gold_error(_("/dev/urandom: expected %zu bytes, got %zd bytes"),
2831 desc.assign(buffer, uuidsz);
2834 else if (strncmp(style, "0x", 2) == 0)
2837 const char* p = style + 2;
2840 if (hex_p(p[0]) && hex_p(p[1]))
2842 char c = (hex_value(p[0]) << 4) | hex_value(p[1]);
2846 else if (*p == '-' || *p == ':')
2849 gold_fatal(_("--build-id argument '%s' not a valid hex number"),
2852 descsz = desc.size();
2855 gold_fatal(_("unrecognized --build-id argument '%s'"), style);
2858 size_t trailing_padding;
2859 Output_section* os = this->create_note("GNU", elfcpp::NT_GNU_BUILD_ID,
2860 ".note.gnu.build-id", descsz, true,
2867 // We know the value already, so we fill it in now.
2868 gold_assert(desc.size() == descsz);
2870 Output_section_data* posd = new Output_data_const(desc, 4);
2871 os->add_output_section_data(posd);
2873 if (trailing_padding != 0)
2875 posd = new Output_data_zero_fill(trailing_padding, 0);
2876 os->add_output_section_data(posd);
2881 // We need to compute a checksum after we have completed the
2883 gold_assert(trailing_padding == 0);
2884 this->build_id_note_ = new Output_data_zero_fill(descsz, 4);
2885 os->add_output_section_data(this->build_id_note_);
2889 // If we have both .stabXX and .stabXXstr sections, then the sh_link
2890 // field of the former should point to the latter. I'm not sure who
2891 // started this, but the GNU linker does it, and some tools depend
2895 Layout::link_stabs_sections()
2897 if (!this->have_stabstr_section_)
2900 for (Section_list::iterator p = this->section_list_.begin();
2901 p != this->section_list_.end();
2904 if ((*p)->type() != elfcpp::SHT_STRTAB)
2907 const char* name = (*p)->name();
2908 if (strncmp(name, ".stab", 5) != 0)
2911 size_t len = strlen(name);
2912 if (strcmp(name + len - 3, "str") != 0)
2915 std::string stab_name(name, len - 3);
2916 Output_section* stab_sec;
2917 stab_sec = this->find_output_section(stab_name.c_str());
2918 if (stab_sec != NULL)
2919 stab_sec->set_link_section(*p);
2923 // Create .gnu_incremental_inputs and related sections needed
2924 // for the next run of incremental linking to check what has changed.
2927 Layout::create_incremental_info_sections(Symbol_table* symtab)
2929 Incremental_inputs* incr = this->incremental_inputs_;
2931 gold_assert(incr != NULL);
2933 // Create the .gnu_incremental_inputs, _symtab, and _relocs input sections.
2934 incr->create_data_sections(symtab);
2936 // Add the .gnu_incremental_inputs section.
2937 const char* incremental_inputs_name =
2938 this->namepool_.add(".gnu_incremental_inputs", false, NULL);
2939 Output_section* incremental_inputs_os =
2940 this->make_output_section(incremental_inputs_name,
2941 elfcpp::SHT_GNU_INCREMENTAL_INPUTS, 0,
2942 ORDER_INVALID, false);
2943 incremental_inputs_os->add_output_section_data(incr->inputs_section());
2945 // Add the .gnu_incremental_symtab section.
2946 const char* incremental_symtab_name =
2947 this->namepool_.add(".gnu_incremental_symtab", false, NULL);
2948 Output_section* incremental_symtab_os =
2949 this->make_output_section(incremental_symtab_name,
2950 elfcpp::SHT_GNU_INCREMENTAL_SYMTAB, 0,
2951 ORDER_INVALID, false);
2952 incremental_symtab_os->add_output_section_data(incr->symtab_section());
2953 incremental_symtab_os->set_entsize(4);
2955 // Add the .gnu_incremental_relocs section.
2956 const char* incremental_relocs_name =
2957 this->namepool_.add(".gnu_incremental_relocs", false, NULL);
2958 Output_section* incremental_relocs_os =
2959 this->make_output_section(incremental_relocs_name,
2960 elfcpp::SHT_GNU_INCREMENTAL_RELOCS, 0,
2961 ORDER_INVALID, false);
2962 incremental_relocs_os->add_output_section_data(incr->relocs_section());
2963 incremental_relocs_os->set_entsize(incr->relocs_entsize());
2965 // Add the .gnu_incremental_got_plt section.
2966 const char* incremental_got_plt_name =
2967 this->namepool_.add(".gnu_incremental_got_plt", false, NULL);
2968 Output_section* incremental_got_plt_os =
2969 this->make_output_section(incremental_got_plt_name,
2970 elfcpp::SHT_GNU_INCREMENTAL_GOT_PLT, 0,
2971 ORDER_INVALID, false);
2972 incremental_got_plt_os->add_output_section_data(incr->got_plt_section());
2974 // Add the .gnu_incremental_strtab section.
2975 const char* incremental_strtab_name =
2976 this->namepool_.add(".gnu_incremental_strtab", false, NULL);
2977 Output_section* incremental_strtab_os = this->make_output_section(incremental_strtab_name,
2978 elfcpp::SHT_STRTAB, 0,
2979 ORDER_INVALID, false);
2980 Output_data_strtab* strtab_data =
2981 new Output_data_strtab(incr->get_stringpool());
2982 incremental_strtab_os->add_output_section_data(strtab_data);
2984 incremental_inputs_os->set_after_input_sections();
2985 incremental_symtab_os->set_after_input_sections();
2986 incremental_relocs_os->set_after_input_sections();
2987 incremental_got_plt_os->set_after_input_sections();
2989 incremental_inputs_os->set_link_section(incremental_strtab_os);
2990 incremental_symtab_os->set_link_section(incremental_inputs_os);
2991 incremental_relocs_os->set_link_section(incremental_inputs_os);
2992 incremental_got_plt_os->set_link_section(incremental_inputs_os);
2995 // Return whether SEG1 should be before SEG2 in the output file. This
2996 // is based entirely on the segment type and flags. When this is
2997 // called the segment addresses have normally not yet been set.
3000 Layout::segment_precedes(const Output_segment* seg1,
3001 const Output_segment* seg2)
3003 elfcpp::Elf_Word type1 = seg1->type();
3004 elfcpp::Elf_Word type2 = seg2->type();
3006 // The single PT_PHDR segment is required to precede any loadable
3007 // segment. We simply make it always first.
3008 if (type1 == elfcpp::PT_PHDR)
3010 gold_assert(type2 != elfcpp::PT_PHDR);
3013 if (type2 == elfcpp::PT_PHDR)
3016 // The single PT_INTERP segment is required to precede any loadable
3017 // segment. We simply make it always second.
3018 if (type1 == elfcpp::PT_INTERP)
3020 gold_assert(type2 != elfcpp::PT_INTERP);
3023 if (type2 == elfcpp::PT_INTERP)
3026 // We then put PT_LOAD segments before any other segments.
3027 if (type1 == elfcpp::PT_LOAD && type2 != elfcpp::PT_LOAD)
3029 if (type2 == elfcpp::PT_LOAD && type1 != elfcpp::PT_LOAD)
3032 // We put the PT_TLS segment last except for the PT_GNU_RELRO
3033 // segment, because that is where the dynamic linker expects to find
3034 // it (this is just for efficiency; other positions would also work
3036 if (type1 == elfcpp::PT_TLS
3037 && type2 != elfcpp::PT_TLS
3038 && type2 != elfcpp::PT_GNU_RELRO)
3040 if (type2 == elfcpp::PT_TLS
3041 && type1 != elfcpp::PT_TLS
3042 && type1 != elfcpp::PT_GNU_RELRO)
3045 // We put the PT_GNU_RELRO segment last, because that is where the
3046 // dynamic linker expects to find it (as with PT_TLS, this is just
3048 if (type1 == elfcpp::PT_GNU_RELRO && type2 != elfcpp::PT_GNU_RELRO)
3050 if (type2 == elfcpp::PT_GNU_RELRO && type1 != elfcpp::PT_GNU_RELRO)
3053 const elfcpp::Elf_Word flags1 = seg1->flags();
3054 const elfcpp::Elf_Word flags2 = seg2->flags();
3056 // The order of non-PT_LOAD segments is unimportant. We simply sort
3057 // by the numeric segment type and flags values. There should not
3058 // be more than one segment with the same type and flags.
3059 if (type1 != elfcpp::PT_LOAD)
3062 return type1 < type2;
3063 gold_assert(flags1 != flags2);
3064 return flags1 < flags2;
3067 // If the addresses are set already, sort by load address.
3068 if (seg1->are_addresses_set())
3070 if (!seg2->are_addresses_set())
3073 unsigned int section_count1 = seg1->output_section_count();
3074 unsigned int section_count2 = seg2->output_section_count();
3075 if (section_count1 == 0 && section_count2 > 0)
3077 if (section_count1 > 0 && section_count2 == 0)
3080 uint64_t paddr1 = (seg1->are_addresses_set()
3082 : seg1->first_section_load_address());
3083 uint64_t paddr2 = (seg2->are_addresses_set()
3085 : seg2->first_section_load_address());
3087 if (paddr1 != paddr2)
3088 return paddr1 < paddr2;
3090 else if (seg2->are_addresses_set())
3093 // A segment which holds large data comes after a segment which does
3094 // not hold large data.
3095 if (seg1->is_large_data_segment())
3097 if (!seg2->is_large_data_segment())
3100 else if (seg2->is_large_data_segment())
3103 // Otherwise, we sort PT_LOAD segments based on the flags. Readonly
3104 // segments come before writable segments. Then writable segments
3105 // with data come before writable segments without data. Then
3106 // executable segments come before non-executable segments. Then
3107 // the unlikely case of a non-readable segment comes before the
3108 // normal case of a readable segment. If there are multiple
3109 // segments with the same type and flags, we require that the
3110 // address be set, and we sort by virtual address and then physical
3112 if ((flags1 & elfcpp::PF_W) != (flags2 & elfcpp::PF_W))
3113 return (flags1 & elfcpp::PF_W) == 0;
3114 if ((flags1 & elfcpp::PF_W) != 0
3115 && seg1->has_any_data_sections() != seg2->has_any_data_sections())
3116 return seg1->has_any_data_sections();
3117 if ((flags1 & elfcpp::PF_X) != (flags2 & elfcpp::PF_X))
3118 return (flags1 & elfcpp::PF_X) != 0;
3119 if ((flags1 & elfcpp::PF_R) != (flags2 & elfcpp::PF_R))
3120 return (flags1 & elfcpp::PF_R) == 0;
3122 // We shouldn't get here--we shouldn't create segments which we
3123 // can't distinguish. Unless of course we are using a weird linker
3124 // script or overlapping --section-start options.
3125 gold_assert(this->script_options_->saw_phdrs_clause()
3126 || parameters->options().any_section_start());
3130 // Increase OFF so that it is congruent to ADDR modulo ABI_PAGESIZE.
3133 align_file_offset(off_t off, uint64_t addr, uint64_t abi_pagesize)
3135 uint64_t unsigned_off = off;
3136 uint64_t aligned_off = ((unsigned_off & ~(abi_pagesize - 1))
3137 | (addr & (abi_pagesize - 1)));
3138 if (aligned_off < unsigned_off)
3139 aligned_off += abi_pagesize;
3143 // Set the file offsets of all the segments, and all the sections they
3144 // contain. They have all been created. LOAD_SEG must be be laid out
3145 // first. Return the offset of the data to follow.
3148 Layout::set_segment_offsets(const Target* target, Output_segment* load_seg,
3149 unsigned int* pshndx)
3151 // Sort them into the final order. We use a stable sort so that we
3152 // don't randomize the order of indistinguishable segments created
3153 // by linker scripts.
3154 std::stable_sort(this->segment_list_.begin(), this->segment_list_.end(),
3155 Layout::Compare_segments(this));
3157 // Find the PT_LOAD segments, and set their addresses and offsets
3158 // and their section's addresses and offsets.
3159 uint64_t start_addr;
3160 if (parameters->options().user_set_Ttext())
3161 start_addr = parameters->options().Ttext();
3162 else if (parameters->options().output_is_position_independent())
3165 start_addr = target->default_text_segment_address();
3167 uint64_t addr = start_addr;
3170 // If LOAD_SEG is NULL, then the file header and segment headers
3171 // will not be loadable. But they still need to be at offset 0 in
3172 // the file. Set their offsets now.
3173 if (load_seg == NULL)
3175 for (Data_list::iterator p = this->special_output_list_.begin();
3176 p != this->special_output_list_.end();
3179 off = align_address(off, (*p)->addralign());
3180 (*p)->set_address_and_file_offset(0, off);
3181 off += (*p)->data_size();
3185 unsigned int increase_relro = this->increase_relro_;
3186 if (this->script_options_->saw_sections_clause())
3189 const bool check_sections = parameters->options().check_sections();
3190 Output_segment* last_load_segment = NULL;
3192 unsigned int shndx_begin = *pshndx;
3193 unsigned int shndx_load_seg = *pshndx;
3195 for (Segment_list::iterator p = this->segment_list_.begin();
3196 p != this->segment_list_.end();
3199 if ((*p)->type() == elfcpp::PT_LOAD)
3201 if (target->isolate_execinstr())
3203 // When we hit the segment that should contain the
3204 // file headers, reset the file offset so we place
3205 // it and subsequent segments appropriately.
3206 // We'll fix up the preceding segments below.
3214 shndx_load_seg = *pshndx;
3220 // Verify that the file headers fall into the first segment.
3221 if (load_seg != NULL && load_seg != *p)
3226 bool are_addresses_set = (*p)->are_addresses_set();
3227 if (are_addresses_set)
3229 // When it comes to setting file offsets, we care about
3230 // the physical address.
3231 addr = (*p)->paddr();
3233 else if (parameters->options().user_set_Ttext()
3234 && ((*p)->flags() & elfcpp::PF_W) == 0)
3236 are_addresses_set = true;
3238 else if (parameters->options().user_set_Tdata()
3239 && ((*p)->flags() & elfcpp::PF_W) != 0
3240 && (!parameters->options().user_set_Tbss()
3241 || (*p)->has_any_data_sections()))
3243 addr = parameters->options().Tdata();
3244 are_addresses_set = true;
3246 else if (parameters->options().user_set_Tbss()
3247 && ((*p)->flags() & elfcpp::PF_W) != 0
3248 && !(*p)->has_any_data_sections())
3250 addr = parameters->options().Tbss();
3251 are_addresses_set = true;
3254 uint64_t orig_addr = addr;
3255 uint64_t orig_off = off;
3257 uint64_t aligned_addr = 0;
3258 uint64_t abi_pagesize = target->abi_pagesize();
3259 uint64_t common_pagesize = target->common_pagesize();
3261 if (!parameters->options().nmagic()
3262 && !parameters->options().omagic())
3263 (*p)->set_minimum_p_align(common_pagesize);
3265 if (!are_addresses_set)
3267 // Skip the address forward one page, maintaining the same
3268 // position within the page. This lets us store both segments
3269 // overlapping on a single page in the file, but the loader will
3270 // put them on different pages in memory. We will revisit this
3271 // decision once we know the size of the segment.
3273 addr = align_address(addr, (*p)->maximum_alignment());
3274 aligned_addr = addr;
3278 // This is the segment that will contain the file
3279 // headers, so its offset will have to be exactly zero.
3280 gold_assert(orig_off == 0);
3282 // If the target wants a fixed minimum distance from the
3283 // text segment to the read-only segment, move up now.
3284 uint64_t min_addr = start_addr + target->rosegment_gap();
3285 if (addr < min_addr)
3288 // But this is not the first segment! To make its
3289 // address congruent with its offset, that address better
3290 // be aligned to the ABI-mandated page size.
3291 addr = align_address(addr, abi_pagesize);
3292 aligned_addr = addr;
3296 if ((addr & (abi_pagesize - 1)) != 0)
3297 addr = addr + abi_pagesize;
3299 off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
3303 if (!parameters->options().nmagic()
3304 && !parameters->options().omagic())
3305 off = align_file_offset(off, addr, abi_pagesize);
3308 // This is -N or -n with a section script which prevents
3309 // us from using a load segment. We need to ensure that
3310 // the file offset is aligned to the alignment of the
3311 // segment. This is because the linker script
3312 // implicitly assumed a zero offset. If we don't align
3313 // here, then the alignment of the sections in the
3314 // linker script may not match the alignment of the
3315 // sections in the set_section_addresses call below,
3316 // causing an error about dot moving backward.
3317 off = align_address(off, (*p)->maximum_alignment());
3320 unsigned int shndx_hold = *pshndx;
3321 bool has_relro = false;
3322 uint64_t new_addr = (*p)->set_section_addresses(this, false, addr,
3327 // Now that we know the size of this segment, we may be able
3328 // to save a page in memory, at the cost of wasting some
3329 // file space, by instead aligning to the start of a new
3330 // page. Here we use the real machine page size rather than
3331 // the ABI mandated page size. If the segment has been
3332 // aligned so that the relro data ends at a page boundary,
3333 // we do not try to realign it.
3335 if (!are_addresses_set
3337 && aligned_addr != addr
3338 && !parameters->incremental())
3340 uint64_t first_off = (common_pagesize
3342 & (common_pagesize - 1)));
3343 uint64_t last_off = new_addr & (common_pagesize - 1);
3346 && ((aligned_addr & ~ (common_pagesize - 1))
3347 != (new_addr & ~ (common_pagesize - 1)))
3348 && first_off + last_off <= common_pagesize)
3350 *pshndx = shndx_hold;
3351 addr = align_address(aligned_addr, common_pagesize);
3352 addr = align_address(addr, (*p)->maximum_alignment());
3353 off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
3354 off = align_file_offset(off, addr, abi_pagesize);
3356 increase_relro = this->increase_relro_;
3357 if (this->script_options_->saw_sections_clause())
3361 new_addr = (*p)->set_section_addresses(this, true, addr,
3370 // Implement --check-sections. We know that the segments
3371 // are sorted by LMA.
3372 if (check_sections && last_load_segment != NULL)
3374 gold_assert(last_load_segment->paddr() <= (*p)->paddr());
3375 if (last_load_segment->paddr() + last_load_segment->memsz()
3378 unsigned long long lb1 = last_load_segment->paddr();
3379 unsigned long long le1 = lb1 + last_load_segment->memsz();
3380 unsigned long long lb2 = (*p)->paddr();
3381 unsigned long long le2 = lb2 + (*p)->memsz();
3382 gold_error(_("load segment overlap [0x%llx -> 0x%llx] and "
3383 "[0x%llx -> 0x%llx]"),
3384 lb1, le1, lb2, le2);
3387 last_load_segment = *p;
3391 if (load_seg != NULL && target->isolate_execinstr())
3393 // Process the early segments again, setting their file offsets
3394 // so they land after the segments starting at LOAD_SEG.
3395 off = align_file_offset(off, 0, target->abi_pagesize());
3397 for (Segment_list::iterator p = this->segment_list_.begin();
3401 if ((*p)->type() == elfcpp::PT_LOAD)
3403 // We repeat the whole job of assigning addresses and
3404 // offsets, but we really only want to change the offsets and
3405 // must ensure that the addresses all come out the same as
3406 // they did the first time through.
3407 bool has_relro = false;
3408 const uint64_t old_addr = (*p)->vaddr();
3409 const uint64_t old_end = old_addr + (*p)->memsz();
3410 uint64_t new_addr = (*p)->set_section_addresses(this, true,
3416 gold_assert(new_addr == old_end);
3420 gold_assert(shndx_begin == shndx_load_seg);
3423 // Handle the non-PT_LOAD segments, setting their offsets from their
3424 // section's offsets.
3425 for (Segment_list::iterator p = this->segment_list_.begin();
3426 p != this->segment_list_.end();
3429 if ((*p)->type() != elfcpp::PT_LOAD)
3430 (*p)->set_offset((*p)->type() == elfcpp::PT_GNU_RELRO
3435 // Set the TLS offsets for each section in the PT_TLS segment.
3436 if (this->tls_segment_ != NULL)
3437 this->tls_segment_->set_tls_offsets();
3442 // Set the offsets of all the allocated sections when doing a
3443 // relocatable link. This does the same jobs as set_segment_offsets,
3444 // only for a relocatable link.
3447 Layout::set_relocatable_section_offsets(Output_data* file_header,
3448 unsigned int* pshndx)
3452 file_header->set_address_and_file_offset(0, 0);
3453 off += file_header->data_size();
3455 for (Section_list::iterator p = this->section_list_.begin();
3456 p != this->section_list_.end();
3459 // We skip unallocated sections here, except that group sections
3460 // have to come first.
3461 if (((*p)->flags() & elfcpp::SHF_ALLOC) == 0
3462 && (*p)->type() != elfcpp::SHT_GROUP)
3465 off = align_address(off, (*p)->addralign());
3467 // The linker script might have set the address.
3468 if (!(*p)->is_address_valid())
3469 (*p)->set_address(0);
3470 (*p)->set_file_offset(off);
3471 (*p)->finalize_data_size();
3472 off += (*p)->data_size();
3474 (*p)->set_out_shndx(*pshndx);
3481 // Set the file offset of all the sections not associated with a
3485 Layout::set_section_offsets(off_t off, Layout::Section_offset_pass pass)
3487 off_t startoff = off;
3490 for (Section_list::iterator p = this->unattached_section_list_.begin();
3491 p != this->unattached_section_list_.end();
3494 // The symtab section is handled in create_symtab_sections.
3495 if (*p == this->symtab_section_)
3498 // If we've already set the data size, don't set it again.
3499 if ((*p)->is_offset_valid() && (*p)->is_data_size_valid())
3502 if (pass == BEFORE_INPUT_SECTIONS_PASS
3503 && (*p)->requires_postprocessing())
3505 (*p)->create_postprocessing_buffer();
3506 this->any_postprocessing_sections_ = true;
3509 if (pass == BEFORE_INPUT_SECTIONS_PASS
3510 && (*p)->after_input_sections())
3512 else if (pass == POSTPROCESSING_SECTIONS_PASS
3513 && (!(*p)->after_input_sections()
3514 || (*p)->type() == elfcpp::SHT_STRTAB))
3516 else if (pass == STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
3517 && (!(*p)->after_input_sections()
3518 || (*p)->type() != elfcpp::SHT_STRTAB))
3521 if (!parameters->incremental_update())
3523 off = align_address(off, (*p)->addralign());
3524 (*p)->set_file_offset(off);
3525 (*p)->finalize_data_size();
3529 // Incremental update: allocate file space from free list.
3530 (*p)->pre_finalize_data_size();
3531 off_t current_size = (*p)->current_data_size();
3532 off = this->allocate(current_size, (*p)->addralign(), startoff);
3535 if (is_debugging_enabled(DEBUG_INCREMENTAL))
3536 this->free_list_.dump();
3537 gold_assert((*p)->output_section() != NULL);
3538 gold_fallback(_("out of patch space for section %s; "
3539 "relink with --incremental-full"),
3540 (*p)->output_section()->name());
3542 (*p)->set_file_offset(off);
3543 (*p)->finalize_data_size();
3544 if ((*p)->data_size() > current_size)
3546 gold_assert((*p)->output_section() != NULL);
3547 gold_fallback(_("%s: section changed size; "
3548 "relink with --incremental-full"),
3549 (*p)->output_section()->name());
3551 gold_debug(DEBUG_INCREMENTAL,
3552 "set_section_offsets: %08lx %08lx %s",
3553 static_cast<long>(off),
3554 static_cast<long>((*p)->data_size()),
3555 ((*p)->output_section() != NULL
3556 ? (*p)->output_section()->name() : "(special)"));
3559 off += (*p)->data_size();
3563 // At this point the name must be set.
3564 if (pass != STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS)
3565 this->namepool_.add((*p)->name(), false, NULL);
3570 // Set the section indexes of all the sections not associated with a
3574 Layout::set_section_indexes(unsigned int shndx)
3576 for (Section_list::iterator p = this->unattached_section_list_.begin();
3577 p != this->unattached_section_list_.end();
3580 if (!(*p)->has_out_shndx())
3582 (*p)->set_out_shndx(shndx);
3589 // Set the section addresses according to the linker script. This is
3590 // only called when we see a SECTIONS clause. This returns the
3591 // program segment which should hold the file header and segment
3592 // headers, if any. It will return NULL if they should not be in a
3596 Layout::set_section_addresses_from_script(Symbol_table* symtab)
3598 Script_sections* ss = this->script_options_->script_sections();
3599 gold_assert(ss->saw_sections_clause());
3600 return this->script_options_->set_section_addresses(symtab, this);
3603 // Place the orphan sections in the linker script.
3606 Layout::place_orphan_sections_in_script()
3608 Script_sections* ss = this->script_options_->script_sections();
3609 gold_assert(ss->saw_sections_clause());
3611 // Place each orphaned output section in the script.
3612 for (Section_list::iterator p = this->section_list_.begin();
3613 p != this->section_list_.end();
3616 if (!(*p)->found_in_sections_clause())
3617 ss->place_orphan(*p);
3621 // Count the local symbols in the regular symbol table and the dynamic
3622 // symbol table, and build the respective string pools.
3625 Layout::count_local_symbols(const Task* task,
3626 const Input_objects* input_objects)
3628 // First, figure out an upper bound on the number of symbols we'll
3629 // be inserting into each pool. This helps us create the pools with
3630 // the right size, to avoid unnecessary hashtable resizing.
3631 unsigned int symbol_count = 0;
3632 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
3633 p != input_objects->relobj_end();
3635 symbol_count += (*p)->local_symbol_count();
3637 // Go from "upper bound" to "estimate." We overcount for two
3638 // reasons: we double-count symbols that occur in more than one
3639 // object file, and we count symbols that are dropped from the
3640 // output. Add it all together and assume we overcount by 100%.
3643 // We assume all symbols will go into both the sympool and dynpool.
3644 this->sympool_.reserve(symbol_count);
3645 this->dynpool_.reserve(symbol_count);
3647 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
3648 p != input_objects->relobj_end();
3651 Task_lock_obj<Object> tlo(task, *p);
3652 (*p)->count_local_symbols(&this->sympool_, &this->dynpool_);
3656 // Create the symbol table sections. Here we also set the final
3657 // values of the symbols. At this point all the loadable sections are
3658 // fully laid out. SHNUM is the number of sections so far.
3661 Layout::create_symtab_sections(const Input_objects* input_objects,
3662 Symbol_table* symtab,
3668 if (parameters->target().get_size() == 32)
3670 symsize = elfcpp::Elf_sizes<32>::sym_size;
3673 else if (parameters->target().get_size() == 64)
3675 symsize = elfcpp::Elf_sizes<64>::sym_size;
3681 // Compute file offsets relative to the start of the symtab section.
3684 // Save space for the dummy symbol at the start of the section. We
3685 // never bother to write this out--it will just be left as zero.
3687 unsigned int local_symbol_index = 1;
3689 // Add STT_SECTION symbols for each Output section which needs one.
3690 for (Section_list::iterator p = this->section_list_.begin();
3691 p != this->section_list_.end();
3694 if (!(*p)->needs_symtab_index())
3695 (*p)->set_symtab_index(-1U);
3698 (*p)->set_symtab_index(local_symbol_index);
3699 ++local_symbol_index;
3704 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
3705 p != input_objects->relobj_end();
3708 unsigned int index = (*p)->finalize_local_symbols(local_symbol_index,
3710 off += (index - local_symbol_index) * symsize;
3711 local_symbol_index = index;
3714 unsigned int local_symcount = local_symbol_index;
3715 gold_assert(static_cast<off_t>(local_symcount * symsize) == off);
3718 size_t dyn_global_index;
3720 if (this->dynsym_section_ == NULL)
3723 dyn_global_index = 0;
3728 dyn_global_index = this->dynsym_section_->info();
3729 off_t locsize = dyn_global_index * this->dynsym_section_->entsize();
3730 dynoff = this->dynsym_section_->offset() + locsize;
3731 dyncount = (this->dynsym_section_->data_size() - locsize) / symsize;
3732 gold_assert(static_cast<off_t>(dyncount * symsize)
3733 == this->dynsym_section_->data_size() - locsize);
3736 off_t global_off = off;
3737 off = symtab->finalize(off, dynoff, dyn_global_index, dyncount,
3738 &this->sympool_, &local_symcount);
3740 if (!parameters->options().strip_all())
3742 this->sympool_.set_string_offsets();
3744 const char* symtab_name = this->namepool_.add(".symtab", false, NULL);
3745 Output_section* osymtab = this->make_output_section(symtab_name,
3749 this->symtab_section_ = osymtab;
3751 Output_section_data* pos = new Output_data_fixed_space(off, align,
3753 osymtab->add_output_section_data(pos);
3755 // We generate a .symtab_shndx section if we have more than
3756 // SHN_LORESERVE sections. Technically it is possible that we
3757 // don't need one, because it is possible that there are no
3758 // symbols in any of sections with indexes larger than
3759 // SHN_LORESERVE. That is probably unusual, though, and it is
3760 // easier to always create one than to compute section indexes
3761 // twice (once here, once when writing out the symbols).
3762 if (shnum >= elfcpp::SHN_LORESERVE)
3764 const char* symtab_xindex_name = this->namepool_.add(".symtab_shndx",
3766 Output_section* osymtab_xindex =
3767 this->make_output_section(symtab_xindex_name,
3768 elfcpp::SHT_SYMTAB_SHNDX, 0,
3769 ORDER_INVALID, false);
3771 size_t symcount = off / symsize;
3772 this->symtab_xindex_ = new Output_symtab_xindex(symcount);
3774 osymtab_xindex->add_output_section_data(this->symtab_xindex_);
3776 osymtab_xindex->set_link_section(osymtab);
3777 osymtab_xindex->set_addralign(4);
3778 osymtab_xindex->set_entsize(4);
3780 osymtab_xindex->set_after_input_sections();
3782 // This tells the driver code to wait until the symbol table
3783 // has written out before writing out the postprocessing
3784 // sections, including the .symtab_shndx section.
3785 this->any_postprocessing_sections_ = true;
3788 const char* strtab_name = this->namepool_.add(".strtab", false, NULL);
3789 Output_section* ostrtab = this->make_output_section(strtab_name,
3794 Output_section_data* pstr = new Output_data_strtab(&this->sympool_);
3795 ostrtab->add_output_section_data(pstr);
3798 if (!parameters->incremental_update())
3799 symtab_off = align_address(*poff, align);
3802 symtab_off = this->allocate(off, align, *poff);
3804 gold_fallback(_("out of patch space for symbol table; "
3805 "relink with --incremental-full"));
3806 gold_debug(DEBUG_INCREMENTAL,
3807 "create_symtab_sections: %08lx %08lx .symtab",
3808 static_cast<long>(symtab_off),
3809 static_cast<long>(off));
3812 symtab->set_file_offset(symtab_off + global_off);
3813 osymtab->set_file_offset(symtab_off);
3814 osymtab->finalize_data_size();
3815 osymtab->set_link_section(ostrtab);
3816 osymtab->set_info(local_symcount);
3817 osymtab->set_entsize(symsize);
3819 if (symtab_off + off > *poff)
3820 *poff = symtab_off + off;
3824 // Create the .shstrtab section, which holds the names of the
3825 // sections. At the time this is called, we have created all the
3826 // output sections except .shstrtab itself.
3829 Layout::create_shstrtab()
3831 // FIXME: We don't need to create a .shstrtab section if we are
3832 // stripping everything.
3834 const char* name = this->namepool_.add(".shstrtab", false, NULL);
3836 Output_section* os = this->make_output_section(name, elfcpp::SHT_STRTAB, 0,
3837 ORDER_INVALID, false);
3839 if (strcmp(parameters->options().compress_debug_sections(), "none") != 0)
3841 // We can't write out this section until we've set all the
3842 // section names, and we don't set the names of compressed
3843 // output sections until relocations are complete. FIXME: With
3844 // the current names we use, this is unnecessary.
3845 os->set_after_input_sections();
3848 Output_section_data* posd = new Output_data_strtab(&this->namepool_);
3849 os->add_output_section_data(posd);
3854 // Create the section headers. SIZE is 32 or 64. OFF is the file
3858 Layout::create_shdrs(const Output_section* shstrtab_section, off_t* poff)
3860 Output_section_headers* oshdrs;
3861 oshdrs = new Output_section_headers(this,
3862 &this->segment_list_,
3863 &this->section_list_,
3864 &this->unattached_section_list_,
3868 if (!parameters->incremental_update())
3869 off = align_address(*poff, oshdrs->addralign());
3872 oshdrs->pre_finalize_data_size();
3873 off = this->allocate(oshdrs->data_size(), oshdrs->addralign(), *poff);
3875 gold_fallback(_("out of patch space for section header table; "
3876 "relink with --incremental-full"));
3877 gold_debug(DEBUG_INCREMENTAL,
3878 "create_shdrs: %08lx %08lx (section header table)",
3879 static_cast<long>(off),
3880 static_cast<long>(off + oshdrs->data_size()));
3882 oshdrs->set_address_and_file_offset(0, off);
3883 off += oshdrs->data_size();
3886 this->section_headers_ = oshdrs;
3889 // Count the allocated sections.
3892 Layout::allocated_output_section_count() const
3894 size_t section_count = 0;
3895 for (Segment_list::const_iterator p = this->segment_list_.begin();
3896 p != this->segment_list_.end();
3898 section_count += (*p)->output_section_count();
3899 return section_count;
3902 // Create the dynamic symbol table.
3905 Layout::create_dynamic_symtab(const Input_objects* input_objects,
3906 Symbol_table* symtab,
3907 Output_section** pdynstr,
3908 unsigned int* plocal_dynamic_count,
3909 std::vector<Symbol*>* pdynamic_symbols,
3910 Versions* pversions)
3912 // Count all the symbols in the dynamic symbol table, and set the
3913 // dynamic symbol indexes.
3915 // Skip symbol 0, which is always all zeroes.
3916 unsigned int index = 1;
3918 // Add STT_SECTION symbols for each Output section which needs one.
3919 for (Section_list::iterator p = this->section_list_.begin();
3920 p != this->section_list_.end();
3923 if (!(*p)->needs_dynsym_index())
3924 (*p)->set_dynsym_index(-1U);
3927 (*p)->set_dynsym_index(index);
3932 // Count the local symbols that need to go in the dynamic symbol table,
3933 // and set the dynamic symbol indexes.
3934 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
3935 p != input_objects->relobj_end();
3938 unsigned int new_index = (*p)->set_local_dynsym_indexes(index);
3942 unsigned int local_symcount = index;
3943 *plocal_dynamic_count = local_symcount;
3945 index = symtab->set_dynsym_indexes(index, pdynamic_symbols,
3946 &this->dynpool_, pversions);
3950 const int size = parameters->target().get_size();
3953 symsize = elfcpp::Elf_sizes<32>::sym_size;
3956 else if (size == 64)
3958 symsize = elfcpp::Elf_sizes<64>::sym_size;
3964 // Create the dynamic symbol table section.
3966 Output_section* dynsym = this->choose_output_section(NULL, ".dynsym",
3970 ORDER_DYNAMIC_LINKER,
3973 // Check for NULL as a linker script may discard .dynsym.
3976 Output_section_data* odata = new Output_data_fixed_space(index * symsize,
3979 dynsym->add_output_section_data(odata);
3981 dynsym->set_info(local_symcount);
3982 dynsym->set_entsize(symsize);
3983 dynsym->set_addralign(align);
3985 this->dynsym_section_ = dynsym;
3988 Output_data_dynamic* const odyn = this->dynamic_data_;
3991 odyn->add_section_address(elfcpp::DT_SYMTAB, dynsym);
3992 odyn->add_constant(elfcpp::DT_SYMENT, symsize);
3995 // If there are more than SHN_LORESERVE allocated sections, we
3996 // create a .dynsym_shndx section. It is possible that we don't
3997 // need one, because it is possible that there are no dynamic
3998 // symbols in any of the sections with indexes larger than
3999 // SHN_LORESERVE. This is probably unusual, though, and at this
4000 // time we don't know the actual section indexes so it is
4001 // inconvenient to check.
4002 if (this->allocated_output_section_count() >= elfcpp::SHN_LORESERVE)
4004 Output_section* dynsym_xindex =
4005 this->choose_output_section(NULL, ".dynsym_shndx",
4006 elfcpp::SHT_SYMTAB_SHNDX,
4008 false, ORDER_DYNAMIC_LINKER, false);
4010 if (dynsym_xindex != NULL)
4012 this->dynsym_xindex_ = new Output_symtab_xindex(index);
4014 dynsym_xindex->add_output_section_data(this->dynsym_xindex_);
4016 dynsym_xindex->set_link_section(dynsym);
4017 dynsym_xindex->set_addralign(4);
4018 dynsym_xindex->set_entsize(4);
4020 dynsym_xindex->set_after_input_sections();
4022 // This tells the driver code to wait until the symbol table
4023 // has written out before writing out the postprocessing
4024 // sections, including the .dynsym_shndx section.
4025 this->any_postprocessing_sections_ = true;
4029 // Create the dynamic string table section.
4031 Output_section* dynstr = this->choose_output_section(NULL, ".dynstr",
4035 ORDER_DYNAMIC_LINKER,
4040 Output_section_data* strdata = new Output_data_strtab(&this->dynpool_);
4041 dynstr->add_output_section_data(strdata);
4044 dynsym->set_link_section(dynstr);
4045 if (this->dynamic_section_ != NULL)
4046 this->dynamic_section_->set_link_section(dynstr);
4050 odyn->add_section_address(elfcpp::DT_STRTAB, dynstr);
4051 odyn->add_section_size(elfcpp::DT_STRSZ, dynstr);
4057 // Create the hash tables.
4059 if (strcmp(parameters->options().hash_style(), "sysv") == 0
4060 || strcmp(parameters->options().hash_style(), "both") == 0)
4062 unsigned char* phash;
4063 unsigned int hashlen;
4064 Dynobj::create_elf_hash_table(*pdynamic_symbols, local_symcount,
4067 Output_section* hashsec =
4068 this->choose_output_section(NULL, ".hash", elfcpp::SHT_HASH,
4069 elfcpp::SHF_ALLOC, false,
4070 ORDER_DYNAMIC_LINKER, false);
4072 Output_section_data* hashdata = new Output_data_const_buffer(phash,
4076 if (hashsec != NULL && hashdata != NULL)
4077 hashsec->add_output_section_data(hashdata);
4079 if (hashsec != NULL)
4082 hashsec->set_link_section(dynsym);
4083 hashsec->set_entsize(4);
4087 odyn->add_section_address(elfcpp::DT_HASH, hashsec);
4090 if (strcmp(parameters->options().hash_style(), "gnu") == 0
4091 || strcmp(parameters->options().hash_style(), "both") == 0)
4093 unsigned char* phash;
4094 unsigned int hashlen;
4095 Dynobj::create_gnu_hash_table(*pdynamic_symbols, local_symcount,
4098 Output_section* hashsec =
4099 this->choose_output_section(NULL, ".gnu.hash", elfcpp::SHT_GNU_HASH,
4100 elfcpp::SHF_ALLOC, false,
4101 ORDER_DYNAMIC_LINKER, false);
4103 Output_section_data* hashdata = new Output_data_const_buffer(phash,
4107 if (hashsec != NULL && hashdata != NULL)
4108 hashsec->add_output_section_data(hashdata);
4110 if (hashsec != NULL)
4113 hashsec->set_link_section(dynsym);
4115 // For a 64-bit target, the entries in .gnu.hash do not have
4116 // a uniform size, so we only set the entry size for a
4118 if (parameters->target().get_size() == 32)
4119 hashsec->set_entsize(4);
4122 odyn->add_section_address(elfcpp::DT_GNU_HASH, hashsec);
4127 // Assign offsets to each local portion of the dynamic symbol table.
4130 Layout::assign_local_dynsym_offsets(const Input_objects* input_objects)
4132 Output_section* dynsym = this->dynsym_section_;
4136 off_t off = dynsym->offset();
4138 // Skip the dummy symbol at the start of the section.
4139 off += dynsym->entsize();
4141 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
4142 p != input_objects->relobj_end();
4145 unsigned int count = (*p)->set_local_dynsym_offset(off);
4146 off += count * dynsym->entsize();
4150 // Create the version sections.
4153 Layout::create_version_sections(const Versions* versions,
4154 const Symbol_table* symtab,
4155 unsigned int local_symcount,
4156 const std::vector<Symbol*>& dynamic_symbols,
4157 const Output_section* dynstr)
4159 if (!versions->any_defs() && !versions->any_needs())
4162 switch (parameters->size_and_endianness())
4164 #ifdef HAVE_TARGET_32_LITTLE
4165 case Parameters::TARGET_32_LITTLE:
4166 this->sized_create_version_sections<32, false>(versions, symtab,
4168 dynamic_symbols, dynstr);
4171 #ifdef HAVE_TARGET_32_BIG
4172 case Parameters::TARGET_32_BIG:
4173 this->sized_create_version_sections<32, true>(versions, symtab,
4175 dynamic_symbols, dynstr);
4178 #ifdef HAVE_TARGET_64_LITTLE
4179 case Parameters::TARGET_64_LITTLE:
4180 this->sized_create_version_sections<64, false>(versions, symtab,
4182 dynamic_symbols, dynstr);
4185 #ifdef HAVE_TARGET_64_BIG
4186 case Parameters::TARGET_64_BIG:
4187 this->sized_create_version_sections<64, true>(versions, symtab,
4189 dynamic_symbols, dynstr);
4197 // Create the version sections, sized version.
4199 template<int size, bool big_endian>
4201 Layout::sized_create_version_sections(
4202 const Versions* versions,
4203 const Symbol_table* symtab,
4204 unsigned int local_symcount,
4205 const std::vector<Symbol*>& dynamic_symbols,
4206 const Output_section* dynstr)
4208 Output_section* vsec = this->choose_output_section(NULL, ".gnu.version",
4209 elfcpp::SHT_GNU_versym,
4212 ORDER_DYNAMIC_LINKER,
4215 // Check for NULL since a linker script may discard this section.
4218 unsigned char* vbuf;
4220 versions->symbol_section_contents<size, big_endian>(symtab,
4226 Output_section_data* vdata = new Output_data_const_buffer(vbuf, vsize, 2,
4229 vsec->add_output_section_data(vdata);
4230 vsec->set_entsize(2);
4231 vsec->set_link_section(this->dynsym_section_);
4234 Output_data_dynamic* const odyn = this->dynamic_data_;
4235 if (odyn != NULL && vsec != NULL)
4236 odyn->add_section_address(elfcpp::DT_VERSYM, vsec);
4238 if (versions->any_defs())
4240 Output_section* vdsec;
4241 vdsec = this->choose_output_section(NULL, ".gnu.version_d",
4242 elfcpp::SHT_GNU_verdef,
4244 false, ORDER_DYNAMIC_LINKER, false);
4248 unsigned char* vdbuf;
4249 unsigned int vdsize;
4250 unsigned int vdentries;
4251 versions->def_section_contents<size, big_endian>(&this->dynpool_,
4255 Output_section_data* vddata =
4256 new Output_data_const_buffer(vdbuf, vdsize, 4, "** version defs");
4258 vdsec->add_output_section_data(vddata);
4259 vdsec->set_link_section(dynstr);
4260 vdsec->set_info(vdentries);
4264 odyn->add_section_address(elfcpp::DT_VERDEF, vdsec);
4265 odyn->add_constant(elfcpp::DT_VERDEFNUM, vdentries);
4270 if (versions->any_needs())
4272 Output_section* vnsec;
4273 vnsec = this->choose_output_section(NULL, ".gnu.version_r",
4274 elfcpp::SHT_GNU_verneed,
4276 false, ORDER_DYNAMIC_LINKER, false);
4280 unsigned char* vnbuf;
4281 unsigned int vnsize;
4282 unsigned int vnentries;
4283 versions->need_section_contents<size, big_endian>(&this->dynpool_,
4287 Output_section_data* vndata =
4288 new Output_data_const_buffer(vnbuf, vnsize, 4, "** version refs");
4290 vnsec->add_output_section_data(vndata);
4291 vnsec->set_link_section(dynstr);
4292 vnsec->set_info(vnentries);
4296 odyn->add_section_address(elfcpp::DT_VERNEED, vnsec);
4297 odyn->add_constant(elfcpp::DT_VERNEEDNUM, vnentries);
4303 // Create the .interp section and PT_INTERP segment.
4306 Layout::create_interp(const Target* target)
4308 gold_assert(this->interp_segment_ == NULL);
4310 const char* interp = parameters->options().dynamic_linker();
4313 interp = target->dynamic_linker();
4314 gold_assert(interp != NULL);
4317 size_t len = strlen(interp) + 1;
4319 Output_section_data* odata = new Output_data_const(interp, len, 1);
4321 Output_section* osec = this->choose_output_section(NULL, ".interp",
4322 elfcpp::SHT_PROGBITS,
4324 false, ORDER_INTERP,
4327 osec->add_output_section_data(odata);
4330 // Add dynamic tags for the PLT and the dynamic relocs. This is
4331 // called by the target-specific code. This does nothing if not doing
4334 // USE_REL is true for REL relocs rather than RELA relocs.
4336 // If PLT_GOT is not NULL, then DT_PLTGOT points to it.
4338 // If PLT_REL is not NULL, it is used for DT_PLTRELSZ, and DT_JMPREL,
4339 // and we also set DT_PLTREL. We use PLT_REL's output section, since
4340 // some targets have multiple reloc sections in PLT_REL.
4342 // If DYN_REL is not NULL, it is used for DT_REL/DT_RELA,
4343 // DT_RELSZ/DT_RELASZ, DT_RELENT/DT_RELAENT. Again we use the output
4346 // If ADD_DEBUG is true, we add a DT_DEBUG entry when generating an
4350 Layout::add_target_dynamic_tags(bool use_rel, const Output_data* plt_got,
4351 const Output_data* plt_rel,
4352 const Output_data_reloc_generic* dyn_rel,
4353 bool add_debug, bool dynrel_includes_plt)
4355 Output_data_dynamic* odyn = this->dynamic_data_;
4359 if (plt_got != NULL && plt_got->output_section() != NULL)
4360 odyn->add_section_address(elfcpp::DT_PLTGOT, plt_got);
4362 if (plt_rel != NULL && plt_rel->output_section() != NULL)
4364 odyn->add_section_size(elfcpp::DT_PLTRELSZ, plt_rel->output_section());
4365 odyn->add_section_address(elfcpp::DT_JMPREL, plt_rel->output_section());
4366 odyn->add_constant(elfcpp::DT_PLTREL,
4367 use_rel ? elfcpp::DT_REL : elfcpp::DT_RELA);
4370 if ((dyn_rel != NULL && dyn_rel->output_section() != NULL)
4371 || (dynrel_includes_plt
4373 && plt_rel->output_section() != NULL))
4375 bool have_dyn_rel = dyn_rel != NULL && dyn_rel->output_section() != NULL;
4376 bool have_plt_rel = plt_rel != NULL && plt_rel->output_section() != NULL;
4377 odyn->add_section_address(use_rel ? elfcpp::DT_REL : elfcpp::DT_RELA,
4379 ? dyn_rel->output_section()
4380 : plt_rel->output_section()));
4381 elfcpp::DT size_tag = use_rel ? elfcpp::DT_RELSZ : elfcpp::DT_RELASZ;
4382 if (have_dyn_rel && have_plt_rel && dynrel_includes_plt)
4383 odyn->add_section_size(size_tag,
4384 dyn_rel->output_section(),
4385 plt_rel->output_section());
4386 else if (have_dyn_rel)
4387 odyn->add_section_size(size_tag, dyn_rel->output_section());
4389 odyn->add_section_size(size_tag, plt_rel->output_section());
4390 const int size = parameters->target().get_size();
4395 rel_tag = elfcpp::DT_RELENT;
4397 rel_size = Reloc_types<elfcpp::SHT_REL, 32, false>::reloc_size;
4398 else if (size == 64)
4399 rel_size = Reloc_types<elfcpp::SHT_REL, 64, false>::reloc_size;
4405 rel_tag = elfcpp::DT_RELAENT;
4407 rel_size = Reloc_types<elfcpp::SHT_RELA, 32, false>::reloc_size;
4408 else if (size == 64)
4409 rel_size = Reloc_types<elfcpp::SHT_RELA, 64, false>::reloc_size;
4413 odyn->add_constant(rel_tag, rel_size);
4415 if (parameters->options().combreloc() && have_dyn_rel)
4417 size_t c = dyn_rel->relative_reloc_count();
4419 odyn->add_constant((use_rel
4420 ? elfcpp::DT_RELCOUNT
4421 : elfcpp::DT_RELACOUNT),
4426 if (add_debug && !parameters->options().shared())
4428 // The value of the DT_DEBUG tag is filled in by the dynamic
4429 // linker at run time, and used by the debugger.
4430 odyn->add_constant(elfcpp::DT_DEBUG, 0);
4434 // Finish the .dynamic section and PT_DYNAMIC segment.
4437 Layout::finish_dynamic_section(const Input_objects* input_objects,
4438 const Symbol_table* symtab)
4440 if (!this->script_options_->saw_phdrs_clause()
4441 && this->dynamic_section_ != NULL)
4443 Output_segment* oseg = this->make_output_segment(elfcpp::PT_DYNAMIC,
4446 oseg->add_output_section_to_nonload(this->dynamic_section_,
4447 elfcpp::PF_R | elfcpp::PF_W);
4450 Output_data_dynamic* const odyn = this->dynamic_data_;
4454 for (Input_objects::Dynobj_iterator p = input_objects->dynobj_begin();
4455 p != input_objects->dynobj_end();
4458 if (!(*p)->is_needed() && (*p)->as_needed())
4460 // This dynamic object was linked with --as-needed, but it
4465 odyn->add_string(elfcpp::DT_NEEDED, (*p)->soname());
4468 if (parameters->options().shared())
4470 const char* soname = parameters->options().soname();
4472 odyn->add_string(elfcpp::DT_SONAME, soname);
4475 Symbol* sym = symtab->lookup(parameters->options().init());
4476 if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj())
4477 odyn->add_symbol(elfcpp::DT_INIT, sym);
4479 sym = symtab->lookup(parameters->options().fini());
4480 if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj())
4481 odyn->add_symbol(elfcpp::DT_FINI, sym);
4483 // Look for .init_array, .preinit_array and .fini_array by checking
4485 for(Layout::Section_list::const_iterator p = this->section_list_.begin();
4486 p != this->section_list_.end();
4488 switch((*p)->type())
4490 case elfcpp::SHT_FINI_ARRAY:
4491 odyn->add_section_address(elfcpp::DT_FINI_ARRAY, *p);
4492 odyn->add_section_size(elfcpp::DT_FINI_ARRAYSZ, *p);
4494 case elfcpp::SHT_INIT_ARRAY:
4495 odyn->add_section_address(elfcpp::DT_INIT_ARRAY, *p);
4496 odyn->add_section_size(elfcpp::DT_INIT_ARRAYSZ, *p);
4498 case elfcpp::SHT_PREINIT_ARRAY:
4499 odyn->add_section_address(elfcpp::DT_PREINIT_ARRAY, *p);
4500 odyn->add_section_size(elfcpp::DT_PREINIT_ARRAYSZ, *p);
4506 // Add a DT_RPATH entry if needed.
4507 const General_options::Dir_list& rpath(parameters->options().rpath());
4510 std::string rpath_val;
4511 for (General_options::Dir_list::const_iterator p = rpath.begin();
4515 if (rpath_val.empty())
4516 rpath_val = p->name();
4519 // Eliminate duplicates.
4520 General_options::Dir_list::const_iterator q;
4521 for (q = rpath.begin(); q != p; ++q)
4522 if (q->name() == p->name())
4527 rpath_val += p->name();
4532 odyn->add_string(elfcpp::DT_RPATH, rpath_val);
4533 if (parameters->options().enable_new_dtags())
4534 odyn->add_string(elfcpp::DT_RUNPATH, rpath_val);
4537 // Look for text segments that have dynamic relocations.
4538 bool have_textrel = false;
4539 if (!this->script_options_->saw_sections_clause())
4541 for (Segment_list::const_iterator p = this->segment_list_.begin();
4542 p != this->segment_list_.end();
4545 if ((*p)->type() == elfcpp::PT_LOAD
4546 && ((*p)->flags() & elfcpp::PF_W) == 0
4547 && (*p)->has_dynamic_reloc())
4549 have_textrel = true;
4556 // We don't know the section -> segment mapping, so we are
4557 // conservative and just look for readonly sections with
4558 // relocations. If those sections wind up in writable segments,
4559 // then we have created an unnecessary DT_TEXTREL entry.
4560 for (Section_list::const_iterator p = this->section_list_.begin();
4561 p != this->section_list_.end();
4564 if (((*p)->flags() & elfcpp::SHF_ALLOC) != 0
4565 && ((*p)->flags() & elfcpp::SHF_WRITE) == 0
4566 && (*p)->has_dynamic_reloc())
4568 have_textrel = true;
4574 if (parameters->options().filter() != NULL)
4575 odyn->add_string(elfcpp::DT_FILTER, parameters->options().filter());
4576 if (parameters->options().any_auxiliary())
4578 for (options::String_set::const_iterator p =
4579 parameters->options().auxiliary_begin();
4580 p != parameters->options().auxiliary_end();
4582 odyn->add_string(elfcpp::DT_AUXILIARY, *p);
4585 // Add a DT_FLAGS entry if necessary.
4586 unsigned int flags = 0;
4589 // Add a DT_TEXTREL for compatibility with older loaders.
4590 odyn->add_constant(elfcpp::DT_TEXTREL, 0);
4591 flags |= elfcpp::DF_TEXTREL;
4593 if (parameters->options().text())
4594 gold_error(_("read-only segment has dynamic relocations"));
4595 else if (parameters->options().warn_shared_textrel()
4596 && parameters->options().shared())
4597 gold_warning(_("shared library text segment is not shareable"));
4599 if (parameters->options().shared() && this->has_static_tls())
4600 flags |= elfcpp::DF_STATIC_TLS;
4601 if (parameters->options().origin())
4602 flags |= elfcpp::DF_ORIGIN;
4603 if (parameters->options().Bsymbolic())
4605 flags |= elfcpp::DF_SYMBOLIC;
4606 // Add DT_SYMBOLIC for compatibility with older loaders.
4607 odyn->add_constant(elfcpp::DT_SYMBOLIC, 0);
4609 if (parameters->options().now())
4610 flags |= elfcpp::DF_BIND_NOW;
4612 odyn->add_constant(elfcpp::DT_FLAGS, flags);
4615 if (parameters->options().initfirst())
4616 flags |= elfcpp::DF_1_INITFIRST;
4617 if (parameters->options().interpose())
4618 flags |= elfcpp::DF_1_INTERPOSE;
4619 if (parameters->options().loadfltr())
4620 flags |= elfcpp::DF_1_LOADFLTR;
4621 if (parameters->options().nodefaultlib())
4622 flags |= elfcpp::DF_1_NODEFLIB;
4623 if (parameters->options().nodelete())
4624 flags |= elfcpp::DF_1_NODELETE;
4625 if (parameters->options().nodlopen())
4626 flags |= elfcpp::DF_1_NOOPEN;
4627 if (parameters->options().nodump())
4628 flags |= elfcpp::DF_1_NODUMP;
4629 if (!parameters->options().shared())
4630 flags &= ~(elfcpp::DF_1_INITFIRST
4631 | elfcpp::DF_1_NODELETE
4632 | elfcpp::DF_1_NOOPEN);
4633 if (parameters->options().origin())
4634 flags |= elfcpp::DF_1_ORIGIN;
4635 if (parameters->options().now())
4636 flags |= elfcpp::DF_1_NOW;
4637 if (parameters->options().Bgroup())
4638 flags |= elfcpp::DF_1_GROUP;
4640 odyn->add_constant(elfcpp::DT_FLAGS_1, flags);
4643 // Set the size of the _DYNAMIC symbol table to be the size of the
4647 Layout::set_dynamic_symbol_size(const Symbol_table* symtab)
4649 Output_data_dynamic* const odyn = this->dynamic_data_;
4652 odyn->finalize_data_size();
4653 if (this->dynamic_symbol_ == NULL)
4655 off_t data_size = odyn->data_size();
4656 const int size = parameters->target().get_size();
4658 symtab->get_sized_symbol<32>(this->dynamic_symbol_)->set_symsize(data_size);
4659 else if (size == 64)
4660 symtab->get_sized_symbol<64>(this->dynamic_symbol_)->set_symsize(data_size);
4665 // The mapping of input section name prefixes to output section names.
4666 // In some cases one prefix is itself a prefix of another prefix; in
4667 // such a case the longer prefix must come first. These prefixes are
4668 // based on the GNU linker default ELF linker script.
4670 #define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 }
4671 #define MAPPING_INIT_EXACT(f, t) { f, 0, t, sizeof(t) - 1 }
4672 const Layout::Section_name_mapping Layout::section_name_mapping[] =
4674 MAPPING_INIT(".text.", ".text"),
4675 MAPPING_INIT(".rodata.", ".rodata"),
4676 MAPPING_INIT(".data.rel.ro.local.", ".data.rel.ro.local"),
4677 MAPPING_INIT_EXACT(".data.rel.ro.local", ".data.rel.ro.local"),
4678 MAPPING_INIT(".data.rel.ro.", ".data.rel.ro"),
4679 MAPPING_INIT_EXACT(".data.rel.ro", ".data.rel.ro"),
4680 MAPPING_INIT(".data.", ".data"),
4681 MAPPING_INIT(".bss.", ".bss"),
4682 MAPPING_INIT(".tdata.", ".tdata"),
4683 MAPPING_INIT(".tbss.", ".tbss"),
4684 MAPPING_INIT(".init_array.", ".init_array"),
4685 MAPPING_INIT(".fini_array.", ".fini_array"),
4686 MAPPING_INIT(".sdata.", ".sdata"),
4687 MAPPING_INIT(".sbss.", ".sbss"),
4688 // FIXME: In the GNU linker, .sbss2 and .sdata2 are handled
4689 // differently depending on whether it is creating a shared library.
4690 MAPPING_INIT(".sdata2.", ".sdata"),
4691 MAPPING_INIT(".sbss2.", ".sbss"),
4692 MAPPING_INIT(".lrodata.", ".lrodata"),
4693 MAPPING_INIT(".ldata.", ".ldata"),
4694 MAPPING_INIT(".lbss.", ".lbss"),
4695 MAPPING_INIT(".gcc_except_table.", ".gcc_except_table"),
4696 MAPPING_INIT(".gnu.linkonce.d.rel.ro.local.", ".data.rel.ro.local"),
4697 MAPPING_INIT(".gnu.linkonce.d.rel.ro.", ".data.rel.ro"),
4698 MAPPING_INIT(".gnu.linkonce.t.", ".text"),
4699 MAPPING_INIT(".gnu.linkonce.r.", ".rodata"),
4700 MAPPING_INIT(".gnu.linkonce.d.", ".data"),
4701 MAPPING_INIT(".gnu.linkonce.b.", ".bss"),
4702 MAPPING_INIT(".gnu.linkonce.s.", ".sdata"),
4703 MAPPING_INIT(".gnu.linkonce.sb.", ".sbss"),
4704 MAPPING_INIT(".gnu.linkonce.s2.", ".sdata"),
4705 MAPPING_INIT(".gnu.linkonce.sb2.", ".sbss"),
4706 MAPPING_INIT(".gnu.linkonce.wi.", ".debug_info"),
4707 MAPPING_INIT(".gnu.linkonce.td.", ".tdata"),
4708 MAPPING_INIT(".gnu.linkonce.tb.", ".tbss"),
4709 MAPPING_INIT(".gnu.linkonce.lr.", ".lrodata"),
4710 MAPPING_INIT(".gnu.linkonce.l.", ".ldata"),
4711 MAPPING_INIT(".gnu.linkonce.lb.", ".lbss"),
4712 MAPPING_INIT(".ARM.extab", ".ARM.extab"),
4713 MAPPING_INIT(".gnu.linkonce.armextab.", ".ARM.extab"),
4714 MAPPING_INIT(".ARM.exidx", ".ARM.exidx"),
4715 MAPPING_INIT(".gnu.linkonce.armexidx.", ".ARM.exidx"),
4718 #undef MAPPING_INIT_EXACT
4720 const int Layout::section_name_mapping_count =
4721 (sizeof(Layout::section_name_mapping)
4722 / sizeof(Layout::section_name_mapping[0]));
4724 // Choose the output section name to use given an input section name.
4725 // Set *PLEN to the length of the name. *PLEN is initialized to the
4729 Layout::output_section_name(const Relobj* relobj, const char* name,
4732 // gcc 4.3 generates the following sorts of section names when it
4733 // needs a section name specific to a function:
4739 // .data.rel.local.FN
4741 // .data.rel.ro.local.FN
4748 // The GNU linker maps all of those to the part before the .FN,
4749 // except that .data.rel.local.FN is mapped to .data, and
4750 // .data.rel.ro.local.FN is mapped to .data.rel.ro. The sections
4751 // beginning with .data.rel.ro.local are grouped together.
4753 // For an anonymous namespace, the string FN can contain a '.'.
4755 // Also of interest: .rodata.strN.N, .rodata.cstN, both of which the
4756 // GNU linker maps to .rodata.
4758 // The .data.rel.ro sections are used with -z relro. The sections
4759 // are recognized by name. We use the same names that the GNU
4760 // linker does for these sections.
4762 // It is hard to handle this in a principled way, so we don't even
4763 // try. We use a table of mappings. If the input section name is
4764 // not found in the table, we simply use it as the output section
4767 const Section_name_mapping* psnm = section_name_mapping;
4768 for (int i = 0; i < section_name_mapping_count; ++i, ++psnm)
4770 if (psnm->fromlen > 0)
4772 if (strncmp(name, psnm->from, psnm->fromlen) == 0)
4774 *plen = psnm->tolen;
4780 if (strcmp(name, psnm->from) == 0)
4782 *plen = psnm->tolen;
4788 // As an additional complication, .ctors sections are output in
4789 // either .ctors or .init_array sections, and .dtors sections are
4790 // output in either .dtors or .fini_array sections.
4791 if (is_prefix_of(".ctors.", name) || is_prefix_of(".dtors.", name))
4793 if (parameters->options().ctors_in_init_array())
4796 return name[1] == 'c' ? ".init_array" : ".fini_array";
4801 return name[1] == 'c' ? ".ctors" : ".dtors";
4804 if (parameters->options().ctors_in_init_array()
4805 && (strcmp(name, ".ctors") == 0 || strcmp(name, ".dtors") == 0))
4807 // To make .init_array/.fini_array work with gcc we must exclude
4808 // .ctors and .dtors sections from the crtbegin and crtend
4811 || (!Layout::match_file_name(relobj, "crtbegin")
4812 && !Layout::match_file_name(relobj, "crtend")))
4815 return name[1] == 'c' ? ".init_array" : ".fini_array";
4822 // Return true if RELOBJ is an input file whose base name matches
4823 // FILE_NAME. The base name must have an extension of ".o", and must
4824 // be exactly FILE_NAME.o or FILE_NAME, one character, ".o". This is
4825 // to match crtbegin.o as well as crtbeginS.o without getting confused
4826 // by other possibilities. Overall matching the file name this way is
4827 // a dreadful hack, but the GNU linker does it in order to better
4828 // support gcc, and we need to be compatible.
4831 Layout::match_file_name(const Relobj* relobj, const char* match)
4833 const std::string& file_name(relobj->name());
4834 const char* base_name = lbasename(file_name.c_str());
4835 size_t match_len = strlen(match);
4836 if (strncmp(base_name, match, match_len) != 0)
4838 size_t base_len = strlen(base_name);
4839 if (base_len != match_len + 2 && base_len != match_len + 3)
4841 return memcmp(base_name + base_len - 2, ".o", 2) == 0;
4844 // Check if a comdat group or .gnu.linkonce section with the given
4845 // NAME is selected for the link. If there is already a section,
4846 // *KEPT_SECTION is set to point to the existing section and the
4847 // function returns false. Otherwise, OBJECT, SHNDX, IS_COMDAT, and
4848 // IS_GROUP_NAME are recorded for this NAME in the layout object,
4849 // *KEPT_SECTION is set to the internal copy and the function returns
4853 Layout::find_or_add_kept_section(const std::string& name,
4858 Kept_section** kept_section)
4860 // It's normal to see a couple of entries here, for the x86 thunk
4861 // sections. If we see more than a few, we're linking a C++
4862 // program, and we resize to get more space to minimize rehashing.
4863 if (this->signatures_.size() > 4
4864 && !this->resized_signatures_)
4866 reserve_unordered_map(&this->signatures_,
4867 this->number_of_input_files_ * 64);
4868 this->resized_signatures_ = true;
4871 Kept_section candidate;
4872 std::pair<Signatures::iterator, bool> ins =
4873 this->signatures_.insert(std::make_pair(name, candidate));
4875 if (kept_section != NULL)
4876 *kept_section = &ins.first->second;
4879 // This is the first time we've seen this signature.
4880 ins.first->second.set_object(object);
4881 ins.first->second.set_shndx(shndx);
4883 ins.first->second.set_is_comdat();
4885 ins.first->second.set_is_group_name();
4889 // We have already seen this signature.
4891 if (ins.first->second.is_group_name())
4893 // We've already seen a real section group with this signature.
4894 // If the kept group is from a plugin object, and we're in the
4895 // replacement phase, accept the new one as a replacement.
4896 if (ins.first->second.object() == NULL
4897 && parameters->options().plugins()->in_replacement_phase())
4899 ins.first->second.set_object(object);
4900 ins.first->second.set_shndx(shndx);
4905 else if (is_group_name)
4907 // This is a real section group, and we've already seen a
4908 // linkonce section with this signature. Record that we've seen
4909 // a section group, and don't include this section group.
4910 ins.first->second.set_is_group_name();
4915 // We've already seen a linkonce section and this is a linkonce
4916 // section. These don't block each other--this may be the same
4917 // symbol name with different section types.
4922 // Store the allocated sections into the section list.
4925 Layout::get_allocated_sections(Section_list* section_list) const
4927 for (Section_list::const_iterator p = this->section_list_.begin();
4928 p != this->section_list_.end();
4930 if (((*p)->flags() & elfcpp::SHF_ALLOC) != 0)
4931 section_list->push_back(*p);
4934 // Create an output segment.
4937 Layout::make_output_segment(elfcpp::Elf_Word type, elfcpp::Elf_Word flags)
4939 gold_assert(!parameters->options().relocatable());
4940 Output_segment* oseg = new Output_segment(type, flags);
4941 this->segment_list_.push_back(oseg);
4943 if (type == elfcpp::PT_TLS)
4944 this->tls_segment_ = oseg;
4945 else if (type == elfcpp::PT_GNU_RELRO)
4946 this->relro_segment_ = oseg;
4947 else if (type == elfcpp::PT_INTERP)
4948 this->interp_segment_ = oseg;
4953 // Return the file offset of the normal symbol table.
4956 Layout::symtab_section_offset() const
4958 if (this->symtab_section_ != NULL)
4959 return this->symtab_section_->offset();
4963 // Return the section index of the normal symbol table. It may have
4964 // been stripped by the -s/--strip-all option.
4967 Layout::symtab_section_shndx() const
4969 if (this->symtab_section_ != NULL)
4970 return this->symtab_section_->out_shndx();
4974 // Write out the Output_sections. Most won't have anything to write,
4975 // since most of the data will come from input sections which are
4976 // handled elsewhere. But some Output_sections do have Output_data.
4979 Layout::write_output_sections(Output_file* of) const
4981 for (Section_list::const_iterator p = this->section_list_.begin();
4982 p != this->section_list_.end();
4985 if (!(*p)->after_input_sections())
4990 // Write out data not associated with a section or the symbol table.
4993 Layout::write_data(const Symbol_table* symtab, Output_file* of) const
4995 if (!parameters->options().strip_all())
4997 const Output_section* symtab_section = this->symtab_section_;
4998 for (Section_list::const_iterator p = this->section_list_.begin();
4999 p != this->section_list_.end();
5002 if ((*p)->needs_symtab_index())
5004 gold_assert(symtab_section != NULL);
5005 unsigned int index = (*p)->symtab_index();
5006 gold_assert(index > 0 && index != -1U);
5007 off_t off = (symtab_section->offset()
5008 + index * symtab_section->entsize());
5009 symtab->write_section_symbol(*p, this->symtab_xindex_, of, off);
5014 const Output_section* dynsym_section = this->dynsym_section_;
5015 for (Section_list::const_iterator p = this->section_list_.begin();
5016 p != this->section_list_.end();
5019 if ((*p)->needs_dynsym_index())
5021 gold_assert(dynsym_section != NULL);
5022 unsigned int index = (*p)->dynsym_index();
5023 gold_assert(index > 0 && index != -1U);
5024 off_t off = (dynsym_section->offset()
5025 + index * dynsym_section->entsize());
5026 symtab->write_section_symbol(*p, this->dynsym_xindex_, of, off);
5030 // Write out the Output_data which are not in an Output_section.
5031 for (Data_list::const_iterator p = this->special_output_list_.begin();
5032 p != this->special_output_list_.end();
5037 // Write out the Output_sections which can only be written after the
5038 // input sections are complete.
5041 Layout::write_sections_after_input_sections(Output_file* of)
5043 // Determine the final section offsets, and thus the final output
5044 // file size. Note we finalize the .shstrab last, to allow the
5045 // after_input_section sections to modify their section-names before
5047 if (this->any_postprocessing_sections_)
5049 off_t off = this->output_file_size_;
5050 off = this->set_section_offsets(off, POSTPROCESSING_SECTIONS_PASS);
5052 // Now that we've finalized the names, we can finalize the shstrab.
5054 this->set_section_offsets(off,
5055 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS);
5057 if (off > this->output_file_size_)
5060 this->output_file_size_ = off;
5064 for (Section_list::const_iterator p = this->section_list_.begin();
5065 p != this->section_list_.end();
5068 if ((*p)->after_input_sections())
5072 this->section_headers_->write(of);
5075 // If the build ID requires computing a checksum, do so here, and
5076 // write it out. We compute a checksum over the entire file because
5077 // that is simplest.
5080 Layout::write_build_id(Output_file* of) const
5082 if (this->build_id_note_ == NULL)
5085 const unsigned char* iv = of->get_input_view(0, this->output_file_size_);
5087 unsigned char* ov = of->get_output_view(this->build_id_note_->offset(),
5088 this->build_id_note_->data_size());
5090 const char* style = parameters->options().build_id();
5091 if (strcmp(style, "sha1") == 0)
5094 sha1_init_ctx(&ctx);
5095 sha1_process_bytes(iv, this->output_file_size_, &ctx);
5096 sha1_finish_ctx(&ctx, ov);
5098 else if (strcmp(style, "md5") == 0)
5102 md5_process_bytes(iv, this->output_file_size_, &ctx);
5103 md5_finish_ctx(&ctx, ov);
5108 of->write_output_view(this->build_id_note_->offset(),
5109 this->build_id_note_->data_size(),
5112 of->free_input_view(0, this->output_file_size_, iv);
5115 // Write out a binary file. This is called after the link is
5116 // complete. IN is the temporary output file we used to generate the
5117 // ELF code. We simply walk through the segments, read them from
5118 // their file offset in IN, and write them to their load address in
5119 // the output file. FIXME: with a bit more work, we could support
5120 // S-records and/or Intel hex format here.
5123 Layout::write_binary(Output_file* in) const
5125 gold_assert(parameters->options().oformat_enum()
5126 == General_options::OBJECT_FORMAT_BINARY);
5128 // Get the size of the binary file.
5129 uint64_t max_load_address = 0;
5130 for (Segment_list::const_iterator p = this->segment_list_.begin();
5131 p != this->segment_list_.end();
5134 if ((*p)->type() == elfcpp::PT_LOAD && (*p)->filesz() > 0)
5136 uint64_t max_paddr = (*p)->paddr() + (*p)->filesz();
5137 if (max_paddr > max_load_address)
5138 max_load_address = max_paddr;
5142 Output_file out(parameters->options().output_file_name());
5143 out.open(max_load_address);
5145 for (Segment_list::const_iterator p = this->segment_list_.begin();
5146 p != this->segment_list_.end();
5149 if ((*p)->type() == elfcpp::PT_LOAD && (*p)->filesz() > 0)
5151 const unsigned char* vin = in->get_input_view((*p)->offset(),
5153 unsigned char* vout = out.get_output_view((*p)->paddr(),
5155 memcpy(vout, vin, (*p)->filesz());
5156 out.write_output_view((*p)->paddr(), (*p)->filesz(), vout);
5157 in->free_input_view((*p)->offset(), (*p)->filesz(), vin);
5164 // Print the output sections to the map file.
5167 Layout::print_to_mapfile(Mapfile* mapfile) const
5169 for (Segment_list::const_iterator p = this->segment_list_.begin();
5170 p != this->segment_list_.end();
5172 (*p)->print_sections_to_mapfile(mapfile);
5175 // Print statistical information to stderr. This is used for --stats.
5178 Layout::print_stats() const
5180 this->namepool_.print_stats("section name pool");
5181 this->sympool_.print_stats("output symbol name pool");
5182 this->dynpool_.print_stats("dynamic name pool");
5184 for (Section_list::const_iterator p = this->section_list_.begin();
5185 p != this->section_list_.end();
5187 (*p)->print_merge_stats();
5190 // Write_sections_task methods.
5192 // We can always run this task.
5195 Write_sections_task::is_runnable()
5200 // We need to unlock both OUTPUT_SECTIONS_BLOCKER and FINAL_BLOCKER
5204 Write_sections_task::locks(Task_locker* tl)
5206 tl->add(this, this->output_sections_blocker_);
5207 tl->add(this, this->final_blocker_);
5210 // Run the task--write out the data.
5213 Write_sections_task::run(Workqueue*)
5215 this->layout_->write_output_sections(this->of_);
5218 // Write_data_task methods.
5220 // We can always run this task.
5223 Write_data_task::is_runnable()
5228 // We need to unlock FINAL_BLOCKER when finished.
5231 Write_data_task::locks(Task_locker* tl)
5233 tl->add(this, this->final_blocker_);
5236 // Run the task--write out the data.
5239 Write_data_task::run(Workqueue*)
5241 this->layout_->write_data(this->symtab_, this->of_);
5244 // Write_symbols_task methods.
5246 // We can always run this task.
5249 Write_symbols_task::is_runnable()
5254 // We need to unlock FINAL_BLOCKER when finished.
5257 Write_symbols_task::locks(Task_locker* tl)
5259 tl->add(this, this->final_blocker_);
5262 // Run the task--write out the symbols.
5265 Write_symbols_task::run(Workqueue*)
5267 this->symtab_->write_globals(this->sympool_, this->dynpool_,
5268 this->layout_->symtab_xindex(),
5269 this->layout_->dynsym_xindex(), this->of_);
5272 // Write_after_input_sections_task methods.
5274 // We can only run this task after the input sections have completed.
5277 Write_after_input_sections_task::is_runnable()
5279 if (this->input_sections_blocker_->is_blocked())
5280 return this->input_sections_blocker_;
5284 // We need to unlock FINAL_BLOCKER when finished.
5287 Write_after_input_sections_task::locks(Task_locker* tl)
5289 tl->add(this, this->final_blocker_);
5295 Write_after_input_sections_task::run(Workqueue*)
5297 this->layout_->write_sections_after_input_sections(this->of_);
5300 // Close_task_runner methods.
5302 // Run the task--close the file.
5305 Close_task_runner::run(Workqueue*, const Task*)
5307 // If we need to compute a checksum for the BUILD if, we do so here.
5308 this->layout_->write_build_id(this->of_);
5310 // If we've been asked to create a binary file, we do so here.
5311 if (this->options_->oformat_enum() != General_options::OBJECT_FORMAT_ELF)
5312 this->layout_->write_binary(this->of_);
5317 // Instantiate the templates we need. We could use the configure
5318 // script to restrict this to only the ones for implemented targets.
5320 #ifdef HAVE_TARGET_32_LITTLE
5323 Layout::init_fixed_output_section<32, false>(
5325 elfcpp::Shdr<32, false>& shdr);
5328 #ifdef HAVE_TARGET_32_BIG
5331 Layout::init_fixed_output_section<32, true>(
5333 elfcpp::Shdr<32, true>& shdr);
5336 #ifdef HAVE_TARGET_64_LITTLE
5339 Layout::init_fixed_output_section<64, false>(
5341 elfcpp::Shdr<64, false>& shdr);
5344 #ifdef HAVE_TARGET_64_BIG
5347 Layout::init_fixed_output_section<64, true>(
5349 elfcpp::Shdr<64, true>& shdr);
5352 #ifdef HAVE_TARGET_32_LITTLE
5355 Layout::layout<32, false>(Sized_relobj_file<32, false>* object,
5358 const elfcpp::Shdr<32, false>& shdr,
5359 unsigned int, unsigned int, off_t*);
5362 #ifdef HAVE_TARGET_32_BIG
5365 Layout::layout<32, true>(Sized_relobj_file<32, true>* object,
5368 const elfcpp::Shdr<32, true>& shdr,
5369 unsigned int, unsigned int, off_t*);
5372 #ifdef HAVE_TARGET_64_LITTLE
5375 Layout::layout<64, false>(Sized_relobj_file<64, false>* object,
5378 const elfcpp::Shdr<64, false>& shdr,
5379 unsigned int, unsigned int, off_t*);
5382 #ifdef HAVE_TARGET_64_BIG
5385 Layout::layout<64, true>(Sized_relobj_file<64, true>* object,
5388 const elfcpp::Shdr<64, true>& shdr,
5389 unsigned int, unsigned int, off_t*);
5392 #ifdef HAVE_TARGET_32_LITTLE
5395 Layout::layout_reloc<32, false>(Sized_relobj_file<32, false>* object,
5396 unsigned int reloc_shndx,
5397 const elfcpp::Shdr<32, false>& shdr,
5398 Output_section* data_section,
5399 Relocatable_relocs* rr);
5402 #ifdef HAVE_TARGET_32_BIG
5405 Layout::layout_reloc<32, true>(Sized_relobj_file<32, true>* object,
5406 unsigned int reloc_shndx,
5407 const elfcpp::Shdr<32, true>& shdr,
5408 Output_section* data_section,
5409 Relocatable_relocs* rr);
5412 #ifdef HAVE_TARGET_64_LITTLE
5415 Layout::layout_reloc<64, false>(Sized_relobj_file<64, false>* object,
5416 unsigned int reloc_shndx,
5417 const elfcpp::Shdr<64, false>& shdr,
5418 Output_section* data_section,
5419 Relocatable_relocs* rr);
5422 #ifdef HAVE_TARGET_64_BIG
5425 Layout::layout_reloc<64, true>(Sized_relobj_file<64, true>* object,
5426 unsigned int reloc_shndx,
5427 const elfcpp::Shdr<64, true>& shdr,
5428 Output_section* data_section,
5429 Relocatable_relocs* rr);
5432 #ifdef HAVE_TARGET_32_LITTLE
5435 Layout::layout_group<32, false>(Symbol_table* symtab,
5436 Sized_relobj_file<32, false>* object,
5438 const char* group_section_name,
5439 const char* signature,
5440 const elfcpp::Shdr<32, false>& shdr,
5441 elfcpp::Elf_Word flags,
5442 std::vector<unsigned int>* shndxes);
5445 #ifdef HAVE_TARGET_32_BIG
5448 Layout::layout_group<32, true>(Symbol_table* symtab,
5449 Sized_relobj_file<32, true>* object,
5451 const char* group_section_name,
5452 const char* signature,
5453 const elfcpp::Shdr<32, true>& shdr,
5454 elfcpp::Elf_Word flags,
5455 std::vector<unsigned int>* shndxes);
5458 #ifdef HAVE_TARGET_64_LITTLE
5461 Layout::layout_group<64, false>(Symbol_table* symtab,
5462 Sized_relobj_file<64, false>* object,
5464 const char* group_section_name,
5465 const char* signature,
5466 const elfcpp::Shdr<64, false>& shdr,
5467 elfcpp::Elf_Word flags,
5468 std::vector<unsigned int>* shndxes);
5471 #ifdef HAVE_TARGET_64_BIG
5474 Layout::layout_group<64, true>(Symbol_table* symtab,
5475 Sized_relobj_file<64, true>* object,
5477 const char* group_section_name,
5478 const char* signature,
5479 const elfcpp::Shdr<64, true>& shdr,
5480 elfcpp::Elf_Word flags,
5481 std::vector<unsigned int>* shndxes);
5484 #ifdef HAVE_TARGET_32_LITTLE
5487 Layout::layout_eh_frame<32, false>(Sized_relobj_file<32, false>* object,
5488 const unsigned char* symbols,
5490 const unsigned char* symbol_names,
5491 off_t symbol_names_size,
5493 const elfcpp::Shdr<32, false>& shdr,
5494 unsigned int reloc_shndx,
5495 unsigned int reloc_type,
5499 #ifdef HAVE_TARGET_32_BIG
5502 Layout::layout_eh_frame<32, true>(Sized_relobj_file<32, true>* object,
5503 const unsigned char* symbols,
5505 const unsigned char* symbol_names,
5506 off_t symbol_names_size,
5508 const elfcpp::Shdr<32, true>& shdr,
5509 unsigned int reloc_shndx,
5510 unsigned int reloc_type,
5514 #ifdef HAVE_TARGET_64_LITTLE
5517 Layout::layout_eh_frame<64, false>(Sized_relobj_file<64, false>* object,
5518 const unsigned char* symbols,
5520 const unsigned char* symbol_names,
5521 off_t symbol_names_size,
5523 const elfcpp::Shdr<64, false>& shdr,
5524 unsigned int reloc_shndx,
5525 unsigned int reloc_type,
5529 #ifdef HAVE_TARGET_64_BIG
5532 Layout::layout_eh_frame<64, true>(Sized_relobj_file<64, true>* object,
5533 const unsigned char* symbols,
5535 const unsigned char* symbol_names,
5536 off_t symbol_names_size,
5538 const elfcpp::Shdr<64, true>& shdr,
5539 unsigned int reloc_shndx,
5540 unsigned int reloc_type,
5544 #ifdef HAVE_TARGET_32_LITTLE
5547 Layout::add_to_gdb_index(bool is_type_unit,
5548 Sized_relobj<32, false>* object,
5549 const unsigned char* symbols,
5552 unsigned int reloc_shndx,
5553 unsigned int reloc_type);
5556 #ifdef HAVE_TARGET_32_BIG
5559 Layout::add_to_gdb_index(bool is_type_unit,
5560 Sized_relobj<32, true>* object,
5561 const unsigned char* symbols,
5564 unsigned int reloc_shndx,
5565 unsigned int reloc_type);
5568 #ifdef HAVE_TARGET_64_LITTLE
5571 Layout::add_to_gdb_index(bool is_type_unit,
5572 Sized_relobj<64, false>* object,
5573 const unsigned char* symbols,
5576 unsigned int reloc_shndx,
5577 unsigned int reloc_type);
5580 #ifdef HAVE_TARGET_64_BIG
5583 Layout::add_to_gdb_index(bool is_type_unit,
5584 Sized_relobj<64, true>* object,
5585 const unsigned char* symbols,
5588 unsigned int reloc_shndx,
5589 unsigned int reloc_type);
5592 } // End namespace gold.