1 // layout.cc -- lay out output file sections for gold
3 // Copyright 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
4 // Written by Ian Lance Taylor <iant@google.com>.
6 // This file is part of gold.
8 // This program is free software; you can redistribute it and/or modify
9 // it under the terms of the GNU General Public License as published by
10 // the Free Software Foundation; either version 3 of the License, or
11 // (at your option) any later version.
13 // This program is distributed in the hope that it will be useful,
14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 // GNU General Public License for more details.
18 // You should have received a copy of the GNU General Public License
19 // along with this program; if not, write to the Free Software
20 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
21 // MA 02110-1301, USA.
32 #include "libiberty.h"
36 #include "parameters.h"
40 #include "script-sections.h"
45 #include "compressed_output.h"
46 #include "reduced_debug_output.h"
48 #include "descriptors.h"
50 #include "incremental.h"
56 // Layout_task_runner methods.
58 // Lay out the sections. This is called after all the input objects
62 Layout_task_runner::run(Workqueue
* workqueue
, const Task
* task
)
64 off_t file_size
= this->layout_
->finalize(this->input_objects_
,
69 // Now we know the final size of the output file and we know where
70 // each piece of information goes.
72 if (this->mapfile_
!= NULL
)
74 this->mapfile_
->print_discarded_sections(this->input_objects_
);
75 this->layout_
->print_to_mapfile(this->mapfile_
);
78 Output_file
* of
= new Output_file(parameters
->options().output_file_name());
79 if (this->options_
.oformat_enum() != General_options::OBJECT_FORMAT_ELF
)
80 of
->set_is_temporary();
83 // Queue up the final set of tasks.
84 gold::queue_final_tasks(this->options_
, this->input_objects_
,
85 this->symtab_
, this->layout_
, workqueue
, of
);
90 Layout::Layout(int number_of_input_files
, Script_options
* script_options
)
91 : number_of_input_files_(number_of_input_files
),
92 script_options_(script_options
),
100 unattached_section_list_(),
101 special_output_list_(),
102 section_headers_(NULL
),
104 relro_segment_(NULL
),
105 symtab_section_(NULL
),
106 symtab_xindex_(NULL
),
107 dynsym_section_(NULL
),
108 dynsym_xindex_(NULL
),
109 dynamic_section_(NULL
),
111 eh_frame_section_(NULL
),
112 eh_frame_data_(NULL
),
113 added_eh_frame_data_(false),
114 eh_frame_hdr_section_(NULL
),
115 build_id_note_(NULL
),
119 output_file_size_(-1),
120 sections_are_attached_(false),
121 input_requires_executable_stack_(false),
122 input_with_gnu_stack_note_(false),
123 input_without_gnu_stack_note_(false),
124 has_static_tls_(false),
125 any_postprocessing_sections_(false),
126 resized_signatures_(false),
127 have_stabstr_section_(false),
128 incremental_inputs_(NULL
)
130 // Make space for more than enough segments for a typical file.
131 // This is just for efficiency--it's OK if we wind up needing more.
132 this->segment_list_
.reserve(12);
134 // We expect two unattached Output_data objects: the file header and
135 // the segment headers.
136 this->special_output_list_
.reserve(2);
138 // Initialize structure needed for an incremental build.
139 if (parameters
->options().incremental())
140 this->incremental_inputs_
= new Incremental_inputs
;
142 // The section name pool is worth optimizing in all cases, because
143 // it is small, but there are often overlaps due to .rel sections.
144 this->namepool_
.set_optimize();
147 // Hash a key we use to look up an output section mapping.
150 Layout::Hash_key::operator()(const Layout::Key
& k
) const
152 return k
.first
+ k
.second
.first
+ k
.second
.second
;
155 // Returns whether the given section is in the list of
156 // debug-sections-used-by-some-version-of-gdb. Currently,
157 // we've checked versions of gdb up to and including 6.7.1.
159 static const char* gdb_sections
[] =
161 // ".debug_aranges", // not used by gdb as of 6.7.1
167 // ".debug_pubnames", // not used by gdb as of 6.7.1
172 static const char* lines_only_debug_sections
[] =
174 // ".debug_aranges", // not used by gdb as of 6.7.1
180 // ".debug_pubnames", // not used by gdb as of 6.7.1
186 is_gdb_debug_section(const char* str
)
188 // We can do this faster: binary search or a hashtable. But why bother?
189 for (size_t i
= 0; i
< sizeof(gdb_sections
)/sizeof(*gdb_sections
); ++i
)
190 if (strcmp(str
, gdb_sections
[i
]) == 0)
196 is_lines_only_debug_section(const char* str
)
198 // We can do this faster: binary search or a hashtable. But why bother?
200 i
< sizeof(lines_only_debug_sections
)/sizeof(*lines_only_debug_sections
);
202 if (strcmp(str
, lines_only_debug_sections
[i
]) == 0)
207 // Whether to include this section in the link.
209 template<int size
, bool big_endian
>
211 Layout::include_section(Sized_relobj
<size
, big_endian
>*, const char* name
,
212 const elfcpp::Shdr
<size
, big_endian
>& shdr
)
214 if (shdr
.get_sh_flags() & elfcpp::SHF_EXCLUDE
)
217 switch (shdr
.get_sh_type())
219 case elfcpp::SHT_NULL
:
220 case elfcpp::SHT_SYMTAB
:
221 case elfcpp::SHT_DYNSYM
:
222 case elfcpp::SHT_HASH
:
223 case elfcpp::SHT_DYNAMIC
:
224 case elfcpp::SHT_SYMTAB_SHNDX
:
227 case elfcpp::SHT_STRTAB
:
228 // Discard the sections which have special meanings in the ELF
229 // ABI. Keep others (e.g., .stabstr). We could also do this by
230 // checking the sh_link fields of the appropriate sections.
231 return (strcmp(name
, ".dynstr") != 0
232 && strcmp(name
, ".strtab") != 0
233 && strcmp(name
, ".shstrtab") != 0);
235 case elfcpp::SHT_RELA
:
236 case elfcpp::SHT_REL
:
237 case elfcpp::SHT_GROUP
:
238 // If we are emitting relocations these should be handled
240 gold_assert(!parameters
->options().relocatable()
241 && !parameters
->options().emit_relocs());
244 case elfcpp::SHT_PROGBITS
:
245 if (parameters
->options().strip_debug()
246 && (shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) == 0)
248 if (is_debug_info_section(name
))
251 if (parameters
->options().strip_debug_non_line()
252 && (shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) == 0)
254 // Debugging sections can only be recognized by name.
255 if (is_prefix_of(".debug", name
)
256 && !is_lines_only_debug_section(name
))
259 if (parameters
->options().strip_debug_gdb()
260 && (shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) == 0)
262 // Debugging sections can only be recognized by name.
263 if (is_prefix_of(".debug", name
)
264 && !is_gdb_debug_section(name
))
267 if (parameters
->options().strip_lto_sections()
268 && !parameters
->options().relocatable()
269 && (shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) == 0)
271 // Ignore LTO sections containing intermediate code.
272 if (is_prefix_of(".gnu.lto_", name
))
282 // Return an output section named NAME, or NULL if there is none.
285 Layout::find_output_section(const char* name
) const
287 for (Section_list::const_iterator p
= this->section_list_
.begin();
288 p
!= this->section_list_
.end();
290 if (strcmp((*p
)->name(), name
) == 0)
295 // Return an output segment of type TYPE, with segment flags SET set
296 // and segment flags CLEAR clear. Return NULL if there is none.
299 Layout::find_output_segment(elfcpp::PT type
, elfcpp::Elf_Word set
,
300 elfcpp::Elf_Word clear
) const
302 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
303 p
!= this->segment_list_
.end();
305 if (static_cast<elfcpp::PT
>((*p
)->type()) == type
306 && ((*p
)->flags() & set
) == set
307 && ((*p
)->flags() & clear
) == 0)
312 // Return the output section to use for section NAME with type TYPE
313 // and section flags FLAGS. NAME must be canonicalized in the string
314 // pool, and NAME_KEY is the key.
317 Layout::get_output_section(const char* name
, Stringpool::Key name_key
,
318 elfcpp::Elf_Word type
, elfcpp::Elf_Xword flags
)
320 elfcpp::Elf_Xword lookup_flags
= flags
;
322 // Ignoring SHF_WRITE and SHF_EXECINSTR here means that we combine
323 // read-write with read-only sections. Some other ELF linkers do
324 // not do this. FIXME: Perhaps there should be an option
326 lookup_flags
&= ~(elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
);
328 const Key
key(name_key
, std::make_pair(type
, lookup_flags
));
329 const std::pair
<Key
, Output_section
*> v(key
, NULL
);
330 std::pair
<Section_name_map::iterator
, bool> ins(
331 this->section_name_map_
.insert(v
));
334 return ins
.first
->second
;
337 // This is the first time we've seen this name/type/flags
338 // combination. For compatibility with the GNU linker, we
339 // combine sections with contents and zero flags with sections
340 // with non-zero flags. This is a workaround for cases where
341 // assembler code forgets to set section flags. FIXME: Perhaps
342 // there should be an option to control this.
343 Output_section
* os
= NULL
;
345 if (type
== elfcpp::SHT_PROGBITS
)
349 Output_section
* same_name
= this->find_output_section(name
);
350 if (same_name
!= NULL
351 && same_name
->type() == elfcpp::SHT_PROGBITS
352 && (same_name
->flags() & elfcpp::SHF_TLS
) == 0)
355 else if ((flags
& elfcpp::SHF_TLS
) == 0)
357 elfcpp::Elf_Xword zero_flags
= 0;
358 const Key
zero_key(name_key
, std::make_pair(type
, zero_flags
));
359 Section_name_map::iterator p
=
360 this->section_name_map_
.find(zero_key
);
361 if (p
!= this->section_name_map_
.end())
367 os
= this->make_output_section(name
, type
, flags
);
368 ins
.first
->second
= os
;
373 // Pick the output section to use for section NAME, in input file
374 // RELOBJ, with type TYPE and flags FLAGS. RELOBJ may be NULL for a
375 // linker created section. IS_INPUT_SECTION is true if we are
376 // choosing an output section for an input section found in a input
377 // file. This will return NULL if the input section should be
381 Layout::choose_output_section(const Relobj
* relobj
, const char* name
,
382 elfcpp::Elf_Word type
, elfcpp::Elf_Xword flags
,
383 bool is_input_section
)
385 // We should not see any input sections after we have attached
386 // sections to segments.
387 gold_assert(!is_input_section
|| !this->sections_are_attached_
);
389 // Some flags in the input section should not be automatically
390 // copied to the output section.
391 flags
&= ~ (elfcpp::SHF_INFO_LINK
392 | elfcpp::SHF_LINK_ORDER
395 | elfcpp::SHF_STRINGS
);
397 if (this->script_options_
->saw_sections_clause())
399 // We are using a SECTIONS clause, so the output section is
400 // chosen based only on the name.
402 Script_sections
* ss
= this->script_options_
->script_sections();
403 const char* file_name
= relobj
== NULL
? NULL
: relobj
->name().c_str();
404 Output_section
** output_section_slot
;
405 name
= ss
->output_section_name(file_name
, name
, &output_section_slot
);
408 // The SECTIONS clause says to discard this input section.
412 // If this is an orphan section--one not mentioned in the linker
413 // script--then OUTPUT_SECTION_SLOT will be NULL, and we do the
414 // default processing below.
416 if (output_section_slot
!= NULL
)
418 if (*output_section_slot
!= NULL
)
419 return *output_section_slot
;
421 // We don't put sections found in the linker script into
422 // SECTION_NAME_MAP_. That keeps us from getting confused
423 // if an orphan section is mapped to a section with the same
424 // name as one in the linker script.
426 name
= this->namepool_
.add(name
, false, NULL
);
428 Output_section
* os
= this->make_output_section(name
, type
, flags
);
429 os
->set_found_in_sections_clause();
430 *output_section_slot
= os
;
435 // FIXME: Handle SHF_OS_NONCONFORMING somewhere.
437 // Turn NAME from the name of the input section into the name of the
440 size_t len
= strlen(name
);
442 && !this->script_options_
->saw_sections_clause()
443 && !parameters
->options().relocatable())
444 name
= Layout::output_section_name(name
, &len
);
446 Stringpool::Key name_key
;
447 name
= this->namepool_
.add_with_length(name
, len
, true, &name_key
);
449 // Find or make the output section. The output section is selected
450 // based on the section name, type, and flags.
451 return this->get_output_section(name
, name_key
, type
, flags
);
454 // Return the output section to use for input section SHNDX, with name
455 // NAME, with header HEADER, from object OBJECT. RELOC_SHNDX is the
456 // index of a relocation section which applies to this section, or 0
457 // if none, or -1U if more than one. RELOC_TYPE is the type of the
458 // relocation section if there is one. Set *OFF to the offset of this
459 // input section without the output section. Return NULL if the
460 // section should be discarded. Set *OFF to -1 if the section
461 // contents should not be written directly to the output file, but
462 // will instead receive special handling.
464 template<int size
, bool big_endian
>
466 Layout::layout(Sized_relobj
<size
, big_endian
>* object
, unsigned int shndx
,
467 const char* name
, const elfcpp::Shdr
<size
, big_endian
>& shdr
,
468 unsigned int reloc_shndx
, unsigned int, off_t
* off
)
472 if (!this->include_section(object
, name
, shdr
))
477 // In a relocatable link a grouped section must not be combined with
478 // any other sections.
479 if (parameters
->options().relocatable()
480 && (shdr
.get_sh_flags() & elfcpp::SHF_GROUP
) != 0)
482 name
= this->namepool_
.add(name
, true, NULL
);
483 os
= this->make_output_section(name
, shdr
.get_sh_type(),
484 shdr
.get_sh_flags());
488 os
= this->choose_output_section(object
, name
, shdr
.get_sh_type(),
489 shdr
.get_sh_flags(), true);
494 // By default the GNU linker sorts input sections whose names match
495 // .ctor.*, .dtor.*, .init_array.*, or .fini_array.*. The sections
496 // are sorted by name. This is used to implement constructor
497 // priority ordering. We are compatible.
498 if (!this->script_options_
->saw_sections_clause()
499 && (is_prefix_of(".ctors.", name
)
500 || is_prefix_of(".dtors.", name
)
501 || is_prefix_of(".init_array.", name
)
502 || is_prefix_of(".fini_array.", name
)))
503 os
->set_must_sort_attached_input_sections();
505 // FIXME: Handle SHF_LINK_ORDER somewhere.
507 *off
= os
->add_input_section(object
, shndx
, name
, shdr
, reloc_shndx
,
508 this->script_options_
->saw_sections_clause());
513 // Handle a relocation section when doing a relocatable link.
515 template<int size
, bool big_endian
>
517 Layout::layout_reloc(Sized_relobj
<size
, big_endian
>* object
,
519 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
520 Output_section
* data_section
,
521 Relocatable_relocs
* rr
)
523 gold_assert(parameters
->options().relocatable()
524 || parameters
->options().emit_relocs());
526 int sh_type
= shdr
.get_sh_type();
529 if (sh_type
== elfcpp::SHT_REL
)
531 else if (sh_type
== elfcpp::SHT_RELA
)
535 name
+= data_section
->name();
537 Output_section
* os
= this->choose_output_section(object
, name
.c_str(),
542 os
->set_should_link_to_symtab();
543 os
->set_info_section(data_section
);
545 Output_section_data
* posd
;
546 if (sh_type
== elfcpp::SHT_REL
)
548 os
->set_entsize(elfcpp::Elf_sizes
<size
>::rel_size
);
549 posd
= new Output_relocatable_relocs
<elfcpp::SHT_REL
,
553 else if (sh_type
== elfcpp::SHT_RELA
)
555 os
->set_entsize(elfcpp::Elf_sizes
<size
>::rela_size
);
556 posd
= new Output_relocatable_relocs
<elfcpp::SHT_RELA
,
563 os
->add_output_section_data(posd
);
564 rr
->set_output_data(posd
);
569 // Handle a group section when doing a relocatable link.
571 template<int size
, bool big_endian
>
573 Layout::layout_group(Symbol_table
* symtab
,
574 Sized_relobj
<size
, big_endian
>* object
,
576 const char* group_section_name
,
577 const char* signature
,
578 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
579 elfcpp::Elf_Word flags
,
580 std::vector
<unsigned int>* shndxes
)
582 gold_assert(parameters
->options().relocatable());
583 gold_assert(shdr
.get_sh_type() == elfcpp::SHT_GROUP
);
584 group_section_name
= this->namepool_
.add(group_section_name
, true, NULL
);
585 Output_section
* os
= this->make_output_section(group_section_name
,
587 shdr
.get_sh_flags());
589 // We need to find a symbol with the signature in the symbol table.
590 // If we don't find one now, we need to look again later.
591 Symbol
* sym
= symtab
->lookup(signature
, NULL
);
593 os
->set_info_symndx(sym
);
596 // Reserve some space to minimize reallocations.
597 if (this->group_signatures_
.empty())
598 this->group_signatures_
.reserve(this->number_of_input_files_
* 16);
600 // We will wind up using a symbol whose name is the signature.
601 // So just put the signature in the symbol name pool to save it.
602 signature
= symtab
->canonicalize_name(signature
);
603 this->group_signatures_
.push_back(Group_signature(os
, signature
));
606 os
->set_should_link_to_symtab();
609 section_size_type entry_count
=
610 convert_to_section_size_type(shdr
.get_sh_size() / 4);
611 Output_section_data
* posd
=
612 new Output_data_group
<size
, big_endian
>(object
, entry_count
, flags
,
614 os
->add_output_section_data(posd
);
617 // Special GNU handling of sections name .eh_frame. They will
618 // normally hold exception frame data as defined by the C++ ABI
619 // (http://codesourcery.com/cxx-abi/).
621 template<int size
, bool big_endian
>
623 Layout::layout_eh_frame(Sized_relobj
<size
, big_endian
>* object
,
624 const unsigned char* symbols
,
626 const unsigned char* symbol_names
,
627 off_t symbol_names_size
,
629 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
630 unsigned int reloc_shndx
, unsigned int reloc_type
,
633 gold_assert(shdr
.get_sh_type() == elfcpp::SHT_PROGBITS
);
634 gold_assert((shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) != 0);
636 const char* const name
= ".eh_frame";
637 Output_section
* os
= this->choose_output_section(object
,
639 elfcpp::SHT_PROGBITS
,
645 if (this->eh_frame_section_
== NULL
)
647 this->eh_frame_section_
= os
;
648 this->eh_frame_data_
= new Eh_frame();
650 if (parameters
->options().eh_frame_hdr())
652 Output_section
* hdr_os
=
653 this->choose_output_section(NULL
,
655 elfcpp::SHT_PROGBITS
,
661 Eh_frame_hdr
* hdr_posd
= new Eh_frame_hdr(os
,
662 this->eh_frame_data_
);
663 hdr_os
->add_output_section_data(hdr_posd
);
665 hdr_os
->set_after_input_sections();
667 if (!this->script_options_
->saw_phdrs_clause())
669 Output_segment
* hdr_oseg
;
670 hdr_oseg
= this->make_output_segment(elfcpp::PT_GNU_EH_FRAME
,
672 hdr_oseg
->add_output_section(hdr_os
, elfcpp::PF_R
);
675 this->eh_frame_data_
->set_eh_frame_hdr(hdr_posd
);
680 gold_assert(this->eh_frame_section_
== os
);
682 if (this->eh_frame_data_
->add_ehframe_input_section(object
,
691 os
->update_flags_for_input_section(shdr
.get_sh_flags());
693 // We found a .eh_frame section we are going to optimize, so now
694 // we can add the set of optimized sections to the output
695 // section. We need to postpone adding this until we've found a
696 // section we can optimize so that the .eh_frame section in
697 // crtbegin.o winds up at the start of the output section.
698 if (!this->added_eh_frame_data_
)
700 os
->add_output_section_data(this->eh_frame_data_
);
701 this->added_eh_frame_data_
= true;
707 // We couldn't handle this .eh_frame section for some reason.
708 // Add it as a normal section.
709 bool saw_sections_clause
= this->script_options_
->saw_sections_clause();
710 *off
= os
->add_input_section(object
, shndx
, name
, shdr
, reloc_shndx
,
711 saw_sections_clause
);
717 // Add POSD to an output section using NAME, TYPE, and FLAGS. Return
718 // the output section.
721 Layout::add_output_section_data(const char* name
, elfcpp::Elf_Word type
,
722 elfcpp::Elf_Xword flags
,
723 Output_section_data
* posd
)
725 Output_section
* os
= this->choose_output_section(NULL
, name
, type
, flags
,
728 os
->add_output_section_data(posd
);
732 // Map section flags to segment flags.
735 Layout::section_flags_to_segment(elfcpp::Elf_Xword flags
)
737 elfcpp::Elf_Word ret
= elfcpp::PF_R
;
738 if ((flags
& elfcpp::SHF_WRITE
) != 0)
740 if ((flags
& elfcpp::SHF_EXECINSTR
) != 0)
745 // Sometimes we compress sections. This is typically done for
746 // sections that are not part of normal program execution (such as
747 // .debug_* sections), and where the readers of these sections know
748 // how to deal with compressed sections. (To make it easier for them,
749 // we will rename the ouput section in such cases from .foo to
750 // .foo.zlib.nnnn, where nnnn is the uncompressed size.) This routine
751 // doesn't say for certain whether we'll compress -- it depends on
752 // commandline options as well -- just whether this section is a
753 // candidate for compression.
756 is_compressible_debug_section(const char* secname
)
758 return (strncmp(secname
, ".debug", sizeof(".debug") - 1) == 0);
761 // Make a new Output_section, and attach it to segments as
765 Layout::make_output_section(const char* name
, elfcpp::Elf_Word type
,
766 elfcpp::Elf_Xword flags
)
769 if ((flags
& elfcpp::SHF_ALLOC
) == 0
770 && strcmp(parameters
->options().compress_debug_sections(), "none") != 0
771 && is_compressible_debug_section(name
))
772 os
= new Output_compressed_section(¶meters
->options(), name
, type
,
775 else if ((flags
& elfcpp::SHF_ALLOC
) == 0
776 && parameters
->options().strip_debug_non_line()
777 && strcmp(".debug_abbrev", name
) == 0)
779 os
= this->debug_abbrev_
= new Output_reduced_debug_abbrev_section(
781 if (this->debug_info_
)
782 this->debug_info_
->set_abbreviations(this->debug_abbrev_
);
784 else if ((flags
& elfcpp::SHF_ALLOC
) == 0
785 && parameters
->options().strip_debug_non_line()
786 && strcmp(".debug_info", name
) == 0)
788 os
= this->debug_info_
= new Output_reduced_debug_info_section(
790 if (this->debug_abbrev_
)
791 this->debug_info_
->set_abbreviations(this->debug_abbrev_
);
794 os
= new Output_section(name
, type
, flags
);
796 parameters
->target().new_output_section(os
);
798 this->section_list_
.push_back(os
);
800 // The GNU linker by default sorts some sections by priority, so we
801 // do the same. We need to know that this might happen before we
802 // attach any input sections.
803 if (!this->script_options_
->saw_sections_clause()
804 && (strcmp(name
, ".ctors") == 0
805 || strcmp(name
, ".dtors") == 0
806 || strcmp(name
, ".init_array") == 0
807 || strcmp(name
, ".fini_array") == 0))
808 os
->set_may_sort_attached_input_sections();
810 // With -z relro, we have to recognize the special sections by name.
811 // There is no other way.
812 if (!this->script_options_
->saw_sections_clause()
813 && parameters
->options().relro()
814 && type
== elfcpp::SHT_PROGBITS
815 && (flags
& elfcpp::SHF_ALLOC
) != 0
816 && (flags
& elfcpp::SHF_WRITE
) != 0)
818 if (strcmp(name
, ".data.rel.ro") == 0)
820 else if (strcmp(name
, ".data.rel.ro.local") == 0)
823 os
->set_is_relro_local();
827 // Check for .stab*str sections, as .stab* sections need to link to
829 if (type
== elfcpp::SHT_STRTAB
830 && !this->have_stabstr_section_
831 && strncmp(name
, ".stab", 5) == 0
832 && strcmp(name
+ strlen(name
) - 3, "str") == 0)
833 this->have_stabstr_section_
= true;
835 // If we have already attached the sections to segments, then we
836 // need to attach this one now. This happens for sections created
837 // directly by the linker.
838 if (this->sections_are_attached_
)
839 this->attach_section_to_segment(os
);
844 // Attach output sections to segments. This is called after we have
845 // seen all the input sections.
848 Layout::attach_sections_to_segments()
850 for (Section_list::iterator p
= this->section_list_
.begin();
851 p
!= this->section_list_
.end();
853 this->attach_section_to_segment(*p
);
855 this->sections_are_attached_
= true;
858 // Attach an output section to a segment.
861 Layout::attach_section_to_segment(Output_section
* os
)
863 if ((os
->flags() & elfcpp::SHF_ALLOC
) == 0)
864 this->unattached_section_list_
.push_back(os
);
866 this->attach_allocated_section_to_segment(os
);
869 // Attach an allocated output section to a segment.
872 Layout::attach_allocated_section_to_segment(Output_section
* os
)
874 elfcpp::Elf_Xword flags
= os
->flags();
875 gold_assert((flags
& elfcpp::SHF_ALLOC
) != 0);
877 if (parameters
->options().relocatable())
880 // If we have a SECTIONS clause, we can't handle the attachment to
881 // segments until after we've seen all the sections.
882 if (this->script_options_
->saw_sections_clause())
885 gold_assert(!this->script_options_
->saw_phdrs_clause());
887 // This output section goes into a PT_LOAD segment.
889 elfcpp::Elf_Word seg_flags
= Layout::section_flags_to_segment(flags
);
891 // In general the only thing we really care about for PT_LOAD
892 // segments is whether or not they are writable, so that is how we
893 // search for them. Large data sections also go into their own
894 // PT_LOAD segment. People who need segments sorted on some other
895 // basis will have to use a linker script.
897 Segment_list::const_iterator p
;
898 for (p
= this->segment_list_
.begin();
899 p
!= this->segment_list_
.end();
902 if ((*p
)->type() != elfcpp::PT_LOAD
)
904 if (!parameters
->options().omagic()
905 && ((*p
)->flags() & elfcpp::PF_W
) != (seg_flags
& elfcpp::PF_W
))
907 // If -Tbss was specified, we need to separate the data and BSS
909 if (parameters
->options().user_set_Tbss())
911 if ((os
->type() == elfcpp::SHT_NOBITS
)
912 == (*p
)->has_any_data_sections())
915 if (os
->is_large_data_section() && !(*p
)->is_large_data_segment())
918 (*p
)->add_output_section(os
, seg_flags
);
922 if (p
== this->segment_list_
.end())
924 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_LOAD
,
926 if (os
->is_large_data_section())
927 oseg
->set_is_large_data_segment();
928 oseg
->add_output_section(os
, seg_flags
);
931 // If we see a loadable SHT_NOTE section, we create a PT_NOTE
933 if (os
->type() == elfcpp::SHT_NOTE
)
935 // See if we already have an equivalent PT_NOTE segment.
936 for (p
= this->segment_list_
.begin();
937 p
!= segment_list_
.end();
940 if ((*p
)->type() == elfcpp::PT_NOTE
941 && (((*p
)->flags() & elfcpp::PF_W
)
942 == (seg_flags
& elfcpp::PF_W
)))
944 (*p
)->add_output_section(os
, seg_flags
);
949 if (p
== this->segment_list_
.end())
951 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_NOTE
,
953 oseg
->add_output_section(os
, seg_flags
);
957 // If we see a loadable SHF_TLS section, we create a PT_TLS
958 // segment. There can only be one such segment.
959 if ((flags
& elfcpp::SHF_TLS
) != 0)
961 if (this->tls_segment_
== NULL
)
962 this->make_output_segment(elfcpp::PT_TLS
, seg_flags
);
963 this->tls_segment_
->add_output_section(os
, seg_flags
);
966 // If -z relro is in effect, and we see a relro section, we create a
967 // PT_GNU_RELRO segment. There can only be one such segment.
968 if (os
->is_relro() && parameters
->options().relro())
970 gold_assert(seg_flags
== (elfcpp::PF_R
| elfcpp::PF_W
));
971 if (this->relro_segment_
== NULL
)
972 this->make_output_segment(elfcpp::PT_GNU_RELRO
, seg_flags
);
973 this->relro_segment_
->add_output_section(os
, seg_flags
);
977 // Make an output section for a script.
980 Layout::make_output_section_for_script(const char* name
)
982 name
= this->namepool_
.add(name
, false, NULL
);
983 Output_section
* os
= this->make_output_section(name
, elfcpp::SHT_PROGBITS
,
985 os
->set_found_in_sections_clause();
989 // Return the number of segments we expect to see.
992 Layout::expected_segment_count() const
994 size_t ret
= this->segment_list_
.size();
996 // If we didn't see a SECTIONS clause in a linker script, we should
997 // already have the complete list of segments. Otherwise we ask the
998 // SECTIONS clause how many segments it expects, and add in the ones
999 // we already have (PT_GNU_STACK, PT_GNU_EH_FRAME, etc.)
1001 if (!this->script_options_
->saw_sections_clause())
1005 const Script_sections
* ss
= this->script_options_
->script_sections();
1006 return ret
+ ss
->expected_segment_count(this);
1010 // Handle the .note.GNU-stack section at layout time. SEEN_GNU_STACK
1011 // is whether we saw a .note.GNU-stack section in the object file.
1012 // GNU_STACK_FLAGS is the section flags. The flags give the
1013 // protection required for stack memory. We record this in an
1014 // executable as a PT_GNU_STACK segment. If an object file does not
1015 // have a .note.GNU-stack segment, we must assume that it is an old
1016 // object. On some targets that will force an executable stack.
1019 Layout::layout_gnu_stack(bool seen_gnu_stack
, uint64_t gnu_stack_flags
)
1021 if (!seen_gnu_stack
)
1022 this->input_without_gnu_stack_note_
= true;
1025 this->input_with_gnu_stack_note_
= true;
1026 if ((gnu_stack_flags
& elfcpp::SHF_EXECINSTR
) != 0)
1027 this->input_requires_executable_stack_
= true;
1031 // Create the dynamic sections which are needed before we read the
1035 Layout::create_initial_dynamic_sections(Symbol_table
* symtab
)
1037 if (parameters
->doing_static_link())
1040 this->dynamic_section_
= this->choose_output_section(NULL
, ".dynamic",
1041 elfcpp::SHT_DYNAMIC
,
1043 | elfcpp::SHF_WRITE
),
1045 this->dynamic_section_
->set_is_relro();
1047 symtab
->define_in_output_data("_DYNAMIC", NULL
, this->dynamic_section_
, 0, 0,
1048 elfcpp::STT_OBJECT
, elfcpp::STB_LOCAL
,
1049 elfcpp::STV_HIDDEN
, 0, false, false);
1051 this->dynamic_data_
= new Output_data_dynamic(&this->dynpool_
);
1053 this->dynamic_section_
->add_output_section_data(this->dynamic_data_
);
1056 // For each output section whose name can be represented as C symbol,
1057 // define __start and __stop symbols for the section. This is a GNU
1061 Layout::define_section_symbols(Symbol_table
* symtab
)
1063 for (Section_list::const_iterator p
= this->section_list_
.begin();
1064 p
!= this->section_list_
.end();
1067 const char* const name
= (*p
)->name();
1068 if (name
[strspn(name
,
1070 "ABCDEFGHIJKLMNOPWRSTUVWXYZ"
1071 "abcdefghijklmnopqrstuvwxyz"
1075 const std::string
name_string(name
);
1076 const std::string
start_name("__start_" + name_string
);
1077 const std::string
stop_name("__stop_" + name_string
);
1079 symtab
->define_in_output_data(start_name
.c_str(),
1086 elfcpp::STV_DEFAULT
,
1088 false, // offset_is_from_end
1089 true); // only_if_ref
1091 symtab
->define_in_output_data(stop_name
.c_str(),
1098 elfcpp::STV_DEFAULT
,
1100 true, // offset_is_from_end
1101 true); // only_if_ref
1106 // Define symbols for group signatures.
1109 Layout::define_group_signatures(Symbol_table
* symtab
)
1111 for (Group_signatures::iterator p
= this->group_signatures_
.begin();
1112 p
!= this->group_signatures_
.end();
1115 Symbol
* sym
= symtab
->lookup(p
->signature
, NULL
);
1117 p
->section
->set_info_symndx(sym
);
1120 // Force the name of the group section to the group
1121 // signature, and use the group's section symbol as the
1122 // signature symbol.
1123 if (strcmp(p
->section
->name(), p
->signature
) != 0)
1125 const char* name
= this->namepool_
.add(p
->signature
,
1127 p
->section
->set_name(name
);
1129 p
->section
->set_needs_symtab_index();
1130 p
->section
->set_info_section_symndx(p
->section
);
1134 this->group_signatures_
.clear();
1137 // Find the first read-only PT_LOAD segment, creating one if
1141 Layout::find_first_load_seg()
1143 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
1144 p
!= this->segment_list_
.end();
1147 if ((*p
)->type() == elfcpp::PT_LOAD
1148 && ((*p
)->flags() & elfcpp::PF_R
) != 0
1149 && (parameters
->options().omagic()
1150 || ((*p
)->flags() & elfcpp::PF_W
) == 0))
1154 gold_assert(!this->script_options_
->saw_phdrs_clause());
1156 Output_segment
* load_seg
= this->make_output_segment(elfcpp::PT_LOAD
,
1161 // Finalize the layout. When this is called, we have created all the
1162 // output sections and all the output segments which are based on
1163 // input sections. We have several things to do, and we have to do
1164 // them in the right order, so that we get the right results correctly
1167 // 1) Finalize the list of output segments and create the segment
1170 // 2) Finalize the dynamic symbol table and associated sections.
1172 // 3) Determine the final file offset of all the output segments.
1174 // 4) Determine the final file offset of all the SHF_ALLOC output
1177 // 5) Create the symbol table sections and the section name table
1180 // 6) Finalize the symbol table: set symbol values to their final
1181 // value and make a final determination of which symbols are going
1182 // into the output symbol table.
1184 // 7) Create the section table header.
1186 // 8) Determine the final file offset of all the output sections which
1187 // are not SHF_ALLOC, including the section table header.
1189 // 9) Finalize the ELF file header.
1191 // This function returns the size of the output file.
1194 Layout::finalize(const Input_objects
* input_objects
, Symbol_table
* symtab
,
1195 Target
* target
, const Task
* task
)
1197 target
->finalize_sections(this);
1199 this->count_local_symbols(task
, input_objects
);
1201 this->create_gold_note();
1202 this->create_executable_stack_info(target
);
1203 this->create_build_id();
1204 this->link_stabs_sections();
1206 Output_segment
* phdr_seg
= NULL
;
1207 if (!parameters
->options().relocatable() && !parameters
->doing_static_link())
1209 // There was a dynamic object in the link. We need to create
1210 // some information for the dynamic linker.
1212 // Create the PT_PHDR segment which will hold the program
1214 if (!this->script_options_
->saw_phdrs_clause())
1215 phdr_seg
= this->make_output_segment(elfcpp::PT_PHDR
, elfcpp::PF_R
);
1217 // Create the dynamic symbol table, including the hash table.
1218 Output_section
* dynstr
;
1219 std::vector
<Symbol
*> dynamic_symbols
;
1220 unsigned int local_dynamic_count
;
1221 Versions
versions(*this->script_options()->version_script_info(),
1223 this->create_dynamic_symtab(input_objects
, symtab
, &dynstr
,
1224 &local_dynamic_count
, &dynamic_symbols
,
1227 // Create the .interp section to hold the name of the
1228 // interpreter, and put it in a PT_INTERP segment.
1229 if (!parameters
->options().shared())
1230 this->create_interp(target
);
1232 // Finish the .dynamic section to hold the dynamic data, and put
1233 // it in a PT_DYNAMIC segment.
1234 this->finish_dynamic_section(input_objects
, symtab
);
1236 // We should have added everything we need to the dynamic string
1238 this->dynpool_
.set_string_offsets();
1240 // Create the version sections. We can't do this until the
1241 // dynamic string table is complete.
1242 this->create_version_sections(&versions
, symtab
, local_dynamic_count
,
1243 dynamic_symbols
, dynstr
);
1246 if (this->incremental_inputs_
)
1248 this->incremental_inputs_
->finalize();
1249 this->create_incremental_info_sections();
1252 // If there is a SECTIONS clause, put all the input sections into
1253 // the required order.
1254 Output_segment
* load_seg
;
1255 if (this->script_options_
->saw_sections_clause())
1256 load_seg
= this->set_section_addresses_from_script(symtab
);
1257 else if (parameters
->options().relocatable())
1260 load_seg
= this->find_first_load_seg();
1262 if (parameters
->options().oformat_enum()
1263 != General_options::OBJECT_FORMAT_ELF
)
1266 gold_assert(phdr_seg
== NULL
|| load_seg
!= NULL
);
1268 // Lay out the segment headers.
1269 Output_segment_headers
* segment_headers
;
1270 if (parameters
->options().relocatable())
1271 segment_headers
= NULL
;
1274 segment_headers
= new Output_segment_headers(this->segment_list_
);
1275 if (load_seg
!= NULL
)
1276 load_seg
->add_initial_output_data(segment_headers
);
1277 if (phdr_seg
!= NULL
)
1278 phdr_seg
->add_initial_output_data(segment_headers
);
1281 // Lay out the file header.
1282 Output_file_header
* file_header
;
1283 file_header
= new Output_file_header(target
, symtab
, segment_headers
,
1284 parameters
->options().entry());
1285 if (load_seg
!= NULL
)
1286 load_seg
->add_initial_output_data(file_header
);
1288 this->special_output_list_
.push_back(file_header
);
1289 if (segment_headers
!= NULL
)
1290 this->special_output_list_
.push_back(segment_headers
);
1292 if (this->script_options_
->saw_phdrs_clause()
1293 && !parameters
->options().relocatable())
1295 // Support use of FILEHDRS and PHDRS attachments in a PHDRS
1296 // clause in a linker script.
1297 Script_sections
* ss
= this->script_options_
->script_sections();
1298 ss
->put_headers_in_phdrs(file_header
, segment_headers
);
1301 // We set the output section indexes in set_segment_offsets and
1302 // set_section_indexes.
1303 unsigned int shndx
= 1;
1305 // Set the file offsets of all the segments, and all the sections
1308 if (!parameters
->options().relocatable())
1309 off
= this->set_segment_offsets(target
, load_seg
, &shndx
);
1311 off
= this->set_relocatable_section_offsets(file_header
, &shndx
);
1313 // Set the file offsets of all the non-data sections we've seen so
1314 // far which don't have to wait for the input sections. We need
1315 // this in order to finalize local symbols in non-allocated
1317 off
= this->set_section_offsets(off
, BEFORE_INPUT_SECTIONS_PASS
);
1319 // Set the section indexes of all unallocated sections seen so far,
1320 // in case any of them are somehow referenced by a symbol.
1321 shndx
= this->set_section_indexes(shndx
);
1323 // Create the symbol table sections.
1324 this->create_symtab_sections(input_objects
, symtab
, shndx
, &off
);
1325 if (!parameters
->doing_static_link())
1326 this->assign_local_dynsym_offsets(input_objects
);
1328 // Process any symbol assignments from a linker script. This must
1329 // be called after the symbol table has been finalized.
1330 this->script_options_
->finalize_symbols(symtab
, this);
1332 // Create the .shstrtab section.
1333 Output_section
* shstrtab_section
= this->create_shstrtab();
1335 // Set the file offsets of the rest of the non-data sections which
1336 // don't have to wait for the input sections.
1337 off
= this->set_section_offsets(off
, BEFORE_INPUT_SECTIONS_PASS
);
1339 // Now that all sections have been created, set the section indexes
1340 // for any sections which haven't been done yet.
1341 shndx
= this->set_section_indexes(shndx
);
1343 // Create the section table header.
1344 this->create_shdrs(shstrtab_section
, &off
);
1346 // If there are no sections which require postprocessing, we can
1347 // handle the section names now, and avoid a resize later.
1348 if (!this->any_postprocessing_sections_
)
1349 off
= this->set_section_offsets(off
,
1350 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
);
1352 file_header
->set_section_info(this->section_headers_
, shstrtab_section
);
1354 // Now we know exactly where everything goes in the output file
1355 // (except for non-allocated sections which require postprocessing).
1356 Output_data::layout_complete();
1358 this->output_file_size_
= off
;
1363 // Create a note header following the format defined in the ELF ABI.
1364 // NAME is the name, NOTE_TYPE is the type, SECTION_NAME is the name
1365 // of the section to create, DESCSZ is the size of the descriptor.
1366 // ALLOCATE is true if the section should be allocated in memory.
1367 // This returns the new note section. It sets *TRAILING_PADDING to
1368 // the number of trailing zero bytes required.
1371 Layout::create_note(const char* name
, int note_type
,
1372 const char* section_name
, size_t descsz
,
1373 bool allocate
, size_t* trailing_padding
)
1375 // Authorities all agree that the values in a .note field should
1376 // be aligned on 4-byte boundaries for 32-bit binaries. However,
1377 // they differ on what the alignment is for 64-bit binaries.
1378 // The GABI says unambiguously they take 8-byte alignment:
1379 // http://sco.com/developers/gabi/latest/ch5.pheader.html#note_section
1380 // Other documentation says alignment should always be 4 bytes:
1381 // http://www.netbsd.org/docs/kernel/elf-notes.html#note-format
1382 // GNU ld and GNU readelf both support the latter (at least as of
1383 // version 2.16.91), and glibc always generates the latter for
1384 // .note.ABI-tag (as of version 1.6), so that's the one we go with
1386 #ifdef GABI_FORMAT_FOR_DOTNOTE_SECTION // This is not defined by default.
1387 const int size
= parameters
->target().get_size();
1389 const int size
= 32;
1392 // The contents of the .note section.
1393 size_t namesz
= strlen(name
) + 1;
1394 size_t aligned_namesz
= align_address(namesz
, size
/ 8);
1395 size_t aligned_descsz
= align_address(descsz
, size
/ 8);
1397 size_t notehdrsz
= 3 * (size
/ 8) + aligned_namesz
;
1399 unsigned char* buffer
= new unsigned char[notehdrsz
];
1400 memset(buffer
, 0, notehdrsz
);
1402 bool is_big_endian
= parameters
->target().is_big_endian();
1408 elfcpp::Swap
<32, false>::writeval(buffer
, namesz
);
1409 elfcpp::Swap
<32, false>::writeval(buffer
+ 4, descsz
);
1410 elfcpp::Swap
<32, false>::writeval(buffer
+ 8, note_type
);
1414 elfcpp::Swap
<32, true>::writeval(buffer
, namesz
);
1415 elfcpp::Swap
<32, true>::writeval(buffer
+ 4, descsz
);
1416 elfcpp::Swap
<32, true>::writeval(buffer
+ 8, note_type
);
1419 else if (size
== 64)
1423 elfcpp::Swap
<64, false>::writeval(buffer
, namesz
);
1424 elfcpp::Swap
<64, false>::writeval(buffer
+ 8, descsz
);
1425 elfcpp::Swap
<64, false>::writeval(buffer
+ 16, note_type
);
1429 elfcpp::Swap
<64, true>::writeval(buffer
, namesz
);
1430 elfcpp::Swap
<64, true>::writeval(buffer
+ 8, descsz
);
1431 elfcpp::Swap
<64, true>::writeval(buffer
+ 16, note_type
);
1437 memcpy(buffer
+ 3 * (size
/ 8), name
, namesz
);
1439 elfcpp::Elf_Xword flags
= 0;
1441 flags
= elfcpp::SHF_ALLOC
;
1442 Output_section
* os
= this->choose_output_section(NULL
, section_name
,
1445 Output_section_data
* posd
= new Output_data_const_buffer(buffer
, notehdrsz
,
1448 os
->add_output_section_data(posd
);
1450 *trailing_padding
= aligned_descsz
- descsz
;
1455 // For an executable or shared library, create a note to record the
1456 // version of gold used to create the binary.
1459 Layout::create_gold_note()
1461 if (parameters
->options().relocatable())
1464 std::string desc
= std::string("gold ") + gold::get_version_string();
1466 size_t trailing_padding
;
1467 Output_section
*os
= this->create_note("GNU", elfcpp::NT_GNU_GOLD_VERSION
,
1468 ".note.gnu.gold-version", desc
.size(),
1469 false, &trailing_padding
);
1471 Output_section_data
* posd
= new Output_data_const(desc
, 4);
1472 os
->add_output_section_data(posd
);
1474 if (trailing_padding
> 0)
1476 posd
= new Output_data_zero_fill(trailing_padding
, 0);
1477 os
->add_output_section_data(posd
);
1481 // Record whether the stack should be executable. This can be set
1482 // from the command line using the -z execstack or -z noexecstack
1483 // options. Otherwise, if any input file has a .note.GNU-stack
1484 // section with the SHF_EXECINSTR flag set, the stack should be
1485 // executable. Otherwise, if at least one input file a
1486 // .note.GNU-stack section, and some input file has no .note.GNU-stack
1487 // section, we use the target default for whether the stack should be
1488 // executable. Otherwise, we don't generate a stack note. When
1489 // generating a object file, we create a .note.GNU-stack section with
1490 // the appropriate marking. When generating an executable or shared
1491 // library, we create a PT_GNU_STACK segment.
1494 Layout::create_executable_stack_info(const Target
* target
)
1496 bool is_stack_executable
;
1497 if (parameters
->options().is_execstack_set())
1498 is_stack_executable
= parameters
->options().is_stack_executable();
1499 else if (!this->input_with_gnu_stack_note_
)
1503 if (this->input_requires_executable_stack_
)
1504 is_stack_executable
= true;
1505 else if (this->input_without_gnu_stack_note_
)
1506 is_stack_executable
= target
->is_default_stack_executable();
1508 is_stack_executable
= false;
1511 if (parameters
->options().relocatable())
1513 const char* name
= this->namepool_
.add(".note.GNU-stack", false, NULL
);
1514 elfcpp::Elf_Xword flags
= 0;
1515 if (is_stack_executable
)
1516 flags
|= elfcpp::SHF_EXECINSTR
;
1517 this->make_output_section(name
, elfcpp::SHT_PROGBITS
, flags
);
1521 if (this->script_options_
->saw_phdrs_clause())
1523 int flags
= elfcpp::PF_R
| elfcpp::PF_W
;
1524 if (is_stack_executable
)
1525 flags
|= elfcpp::PF_X
;
1526 this->make_output_segment(elfcpp::PT_GNU_STACK
, flags
);
1530 // If --build-id was used, set up the build ID note.
1533 Layout::create_build_id()
1535 if (!parameters
->options().user_set_build_id())
1538 const char* style
= parameters
->options().build_id();
1539 if (strcmp(style
, "none") == 0)
1542 // Set DESCSZ to the size of the note descriptor. When possible,
1543 // set DESC to the note descriptor contents.
1546 if (strcmp(style
, "md5") == 0)
1548 else if (strcmp(style
, "sha1") == 0)
1550 else if (strcmp(style
, "uuid") == 0)
1552 const size_t uuidsz
= 128 / 8;
1554 char buffer
[uuidsz
];
1555 memset(buffer
, 0, uuidsz
);
1557 int descriptor
= open_descriptor(-1, "/dev/urandom", O_RDONLY
);
1559 gold_error(_("--build-id=uuid failed: could not open /dev/urandom: %s"),
1563 ssize_t got
= ::read(descriptor
, buffer
, uuidsz
);
1564 release_descriptor(descriptor
, true);
1566 gold_error(_("/dev/urandom: read failed: %s"), strerror(errno
));
1567 else if (static_cast<size_t>(got
) != uuidsz
)
1568 gold_error(_("/dev/urandom: expected %zu bytes, got %zd bytes"),
1572 desc
.assign(buffer
, uuidsz
);
1575 else if (strncmp(style
, "0x", 2) == 0)
1578 const char* p
= style
+ 2;
1581 if (hex_p(p
[0]) && hex_p(p
[1]))
1583 char c
= (hex_value(p
[0]) << 4) | hex_value(p
[1]);
1587 else if (*p
== '-' || *p
== ':')
1590 gold_fatal(_("--build-id argument '%s' not a valid hex number"),
1593 descsz
= desc
.size();
1596 gold_fatal(_("unrecognized --build-id argument '%s'"), style
);
1599 size_t trailing_padding
;
1600 Output_section
* os
= this->create_note("GNU", elfcpp::NT_GNU_BUILD_ID
,
1601 ".note.gnu.build-id", descsz
, true,
1606 // We know the value already, so we fill it in now.
1607 gold_assert(desc
.size() == descsz
);
1609 Output_section_data
* posd
= new Output_data_const(desc
, 4);
1610 os
->add_output_section_data(posd
);
1612 if (trailing_padding
!= 0)
1614 posd
= new Output_data_zero_fill(trailing_padding
, 0);
1615 os
->add_output_section_data(posd
);
1620 // We need to compute a checksum after we have completed the
1622 gold_assert(trailing_padding
== 0);
1623 this->build_id_note_
= new Output_data_zero_fill(descsz
, 4);
1624 os
->add_output_section_data(this->build_id_note_
);
1625 os
->set_after_input_sections();
1629 // If we have both .stabXX and .stabXXstr sections, then the sh_link
1630 // field of the former should point to the latter. I'm not sure who
1631 // started this, but the GNU linker does it, and some tools depend
1635 Layout::link_stabs_sections()
1637 if (!this->have_stabstr_section_
)
1640 for (Section_list::iterator p
= this->section_list_
.begin();
1641 p
!= this->section_list_
.end();
1644 if ((*p
)->type() != elfcpp::SHT_STRTAB
)
1647 const char* name
= (*p
)->name();
1648 if (strncmp(name
, ".stab", 5) != 0)
1651 size_t len
= strlen(name
);
1652 if (strcmp(name
+ len
- 3, "str") != 0)
1655 std::string
stab_name(name
, len
- 3);
1656 Output_section
* stab_sec
;
1657 stab_sec
= this->find_output_section(stab_name
.c_str());
1658 if (stab_sec
!= NULL
)
1659 stab_sec
->set_link_section(*p
);
1663 // Create .gnu_incremental_inputs and .gnu_incremental_strtab sections needed
1664 // for the next run of incremental linking to check what has changed.
1667 Layout::create_incremental_info_sections()
1669 gold_assert(this->incremental_inputs_
!= NULL
);
1671 // Add the .gnu_incremental_inputs section.
1672 const char *incremental_inputs_name
=
1673 this->namepool_
.add(".gnu_incremental_inputs", false, NULL
);
1674 Output_section
* inputs_os
=
1675 this->make_output_section(incremental_inputs_name
,
1676 elfcpp::SHT_GNU_INCREMENTAL_INPUTS
, 0);
1677 Output_section_data
* posd
=
1678 this->incremental_inputs_
->create_incremental_inputs_section_data();
1679 inputs_os
->add_output_section_data(posd
);
1681 // Add the .gnu_incremental_strtab section.
1682 const char *incremental_strtab_name
=
1683 this->namepool_
.add(".gnu_incremental_strtab", false, NULL
);
1684 Output_section
* strtab_os
= this->make_output_section(incremental_strtab_name
,
1687 Output_data_strtab
* strtab_data
=
1688 new Output_data_strtab(this->incremental_inputs_
->get_stringpool());
1689 strtab_os
->add_output_section_data(strtab_data
);
1691 inputs_os
->set_link_section(strtab_data
);
1694 // Return whether SEG1 should be before SEG2 in the output file. This
1695 // is based entirely on the segment type and flags. When this is
1696 // called the segment addresses has normally not yet been set.
1699 Layout::segment_precedes(const Output_segment
* seg1
,
1700 const Output_segment
* seg2
)
1702 elfcpp::Elf_Word type1
= seg1
->type();
1703 elfcpp::Elf_Word type2
= seg2
->type();
1705 // The single PT_PHDR segment is required to precede any loadable
1706 // segment. We simply make it always first.
1707 if (type1
== elfcpp::PT_PHDR
)
1709 gold_assert(type2
!= elfcpp::PT_PHDR
);
1712 if (type2
== elfcpp::PT_PHDR
)
1715 // The single PT_INTERP segment is required to precede any loadable
1716 // segment. We simply make it always second.
1717 if (type1
== elfcpp::PT_INTERP
)
1719 gold_assert(type2
!= elfcpp::PT_INTERP
);
1722 if (type2
== elfcpp::PT_INTERP
)
1725 // We then put PT_LOAD segments before any other segments.
1726 if (type1
== elfcpp::PT_LOAD
&& type2
!= elfcpp::PT_LOAD
)
1728 if (type2
== elfcpp::PT_LOAD
&& type1
!= elfcpp::PT_LOAD
)
1731 // We put the PT_TLS segment last except for the PT_GNU_RELRO
1732 // segment, because that is where the dynamic linker expects to find
1733 // it (this is just for efficiency; other positions would also work
1735 if (type1
== elfcpp::PT_TLS
1736 && type2
!= elfcpp::PT_TLS
1737 && type2
!= elfcpp::PT_GNU_RELRO
)
1739 if (type2
== elfcpp::PT_TLS
1740 && type1
!= elfcpp::PT_TLS
1741 && type1
!= elfcpp::PT_GNU_RELRO
)
1744 // We put the PT_GNU_RELRO segment last, because that is where the
1745 // dynamic linker expects to find it (as with PT_TLS, this is just
1747 if (type1
== elfcpp::PT_GNU_RELRO
&& type2
!= elfcpp::PT_GNU_RELRO
)
1749 if (type2
== elfcpp::PT_GNU_RELRO
&& type1
!= elfcpp::PT_GNU_RELRO
)
1752 const elfcpp::Elf_Word flags1
= seg1
->flags();
1753 const elfcpp::Elf_Word flags2
= seg2
->flags();
1755 // The order of non-PT_LOAD segments is unimportant. We simply sort
1756 // by the numeric segment type and flags values. There should not
1757 // be more than one segment with the same type and flags.
1758 if (type1
!= elfcpp::PT_LOAD
)
1761 return type1
< type2
;
1762 gold_assert(flags1
!= flags2
);
1763 return flags1
< flags2
;
1766 // If the addresses are set already, sort by load address.
1767 if (seg1
->are_addresses_set())
1769 if (!seg2
->are_addresses_set())
1772 unsigned int section_count1
= seg1
->output_section_count();
1773 unsigned int section_count2
= seg2
->output_section_count();
1774 if (section_count1
== 0 && section_count2
> 0)
1776 if (section_count1
> 0 && section_count2
== 0)
1779 uint64_t paddr1
= seg1
->first_section_load_address();
1780 uint64_t paddr2
= seg2
->first_section_load_address();
1781 if (paddr1
!= paddr2
)
1782 return paddr1
< paddr2
;
1784 else if (seg2
->are_addresses_set())
1787 // A segment which holds large data comes after a segment which does
1788 // not hold large data.
1789 if (seg1
->is_large_data_segment())
1791 if (!seg2
->is_large_data_segment())
1794 else if (seg2
->is_large_data_segment())
1797 // Otherwise, we sort PT_LOAD segments based on the flags. Readonly
1798 // segments come before writable segments. Then writable segments
1799 // with data come before writable segments without data. Then
1800 // executable segments come before non-executable segments. Then
1801 // the unlikely case of a non-readable segment comes before the
1802 // normal case of a readable segment. If there are multiple
1803 // segments with the same type and flags, we require that the
1804 // address be set, and we sort by virtual address and then physical
1806 if ((flags1
& elfcpp::PF_W
) != (flags2
& elfcpp::PF_W
))
1807 return (flags1
& elfcpp::PF_W
) == 0;
1808 if ((flags1
& elfcpp::PF_W
) != 0
1809 && seg1
->has_any_data_sections() != seg2
->has_any_data_sections())
1810 return seg1
->has_any_data_sections();
1811 if ((flags1
& elfcpp::PF_X
) != (flags2
& elfcpp::PF_X
))
1812 return (flags1
& elfcpp::PF_X
) != 0;
1813 if ((flags1
& elfcpp::PF_R
) != (flags2
& elfcpp::PF_R
))
1814 return (flags1
& elfcpp::PF_R
) == 0;
1816 // We shouldn't get here--we shouldn't create segments which we
1817 // can't distinguish.
1821 // Increase OFF so that it is congruent to ADDR modulo ABI_PAGESIZE.
1824 align_file_offset(off_t off
, uint64_t addr
, uint64_t abi_pagesize
)
1826 uint64_t unsigned_off
= off
;
1827 uint64_t aligned_off
= ((unsigned_off
& ~(abi_pagesize
- 1))
1828 | (addr
& (abi_pagesize
- 1)));
1829 if (aligned_off
< unsigned_off
)
1830 aligned_off
+= abi_pagesize
;
1834 // Set the file offsets of all the segments, and all the sections they
1835 // contain. They have all been created. LOAD_SEG must be be laid out
1836 // first. Return the offset of the data to follow.
1839 Layout::set_segment_offsets(const Target
* target
, Output_segment
* load_seg
,
1840 unsigned int *pshndx
)
1842 // Sort them into the final order.
1843 std::sort(this->segment_list_
.begin(), this->segment_list_
.end(),
1844 Layout::Compare_segments());
1846 // Find the PT_LOAD segments, and set their addresses and offsets
1847 // and their section's addresses and offsets.
1849 if (parameters
->options().user_set_Ttext())
1850 addr
= parameters
->options().Ttext();
1851 else if (parameters
->options().shared())
1854 addr
= target
->default_text_segment_address();
1857 // If LOAD_SEG is NULL, then the file header and segment headers
1858 // will not be loadable. But they still need to be at offset 0 in
1859 // the file. Set their offsets now.
1860 if (load_seg
== NULL
)
1862 for (Data_list::iterator p
= this->special_output_list_
.begin();
1863 p
!= this->special_output_list_
.end();
1866 off
= align_address(off
, (*p
)->addralign());
1867 (*p
)->set_address_and_file_offset(0, off
);
1868 off
+= (*p
)->data_size();
1872 const bool check_sections
= parameters
->options().check_sections();
1873 Output_segment
* last_load_segment
= NULL
;
1875 bool was_readonly
= false;
1876 for (Segment_list::iterator p
= this->segment_list_
.begin();
1877 p
!= this->segment_list_
.end();
1880 if ((*p
)->type() == elfcpp::PT_LOAD
)
1882 if (load_seg
!= NULL
&& load_seg
!= *p
)
1886 bool are_addresses_set
= (*p
)->are_addresses_set();
1887 if (are_addresses_set
)
1889 // When it comes to setting file offsets, we care about
1890 // the physical address.
1891 addr
= (*p
)->paddr();
1893 else if (parameters
->options().user_set_Tdata()
1894 && ((*p
)->flags() & elfcpp::PF_W
) != 0
1895 && (!parameters
->options().user_set_Tbss()
1896 || (*p
)->has_any_data_sections()))
1898 addr
= parameters
->options().Tdata();
1899 are_addresses_set
= true;
1901 else if (parameters
->options().user_set_Tbss()
1902 && ((*p
)->flags() & elfcpp::PF_W
) != 0
1903 && !(*p
)->has_any_data_sections())
1905 addr
= parameters
->options().Tbss();
1906 are_addresses_set
= true;
1909 uint64_t orig_addr
= addr
;
1910 uint64_t orig_off
= off
;
1912 uint64_t aligned_addr
= 0;
1913 uint64_t abi_pagesize
= target
->abi_pagesize();
1914 uint64_t common_pagesize
= target
->common_pagesize();
1916 if (!parameters
->options().nmagic()
1917 && !parameters
->options().omagic())
1918 (*p
)->set_minimum_p_align(common_pagesize
);
1920 if (!are_addresses_set
)
1922 // If the last segment was readonly, and this one is
1923 // not, then skip the address forward one page,
1924 // maintaining the same position within the page. This
1925 // lets us store both segments overlapping on a single
1926 // page in the file, but the loader will put them on
1927 // different pages in memory.
1929 addr
= align_address(addr
, (*p
)->maximum_alignment());
1930 aligned_addr
= addr
;
1932 if (was_readonly
&& ((*p
)->flags() & elfcpp::PF_W
) != 0)
1934 if ((addr
& (abi_pagesize
- 1)) != 0)
1935 addr
= addr
+ abi_pagesize
;
1938 off
= orig_off
+ ((addr
- orig_addr
) & (abi_pagesize
- 1));
1941 if (!parameters
->options().nmagic()
1942 && !parameters
->options().omagic())
1943 off
= align_file_offset(off
, addr
, abi_pagesize
);
1945 unsigned int shndx_hold
= *pshndx
;
1946 uint64_t new_addr
= (*p
)->set_section_addresses(this, false, addr
,
1949 // Now that we know the size of this segment, we may be able
1950 // to save a page in memory, at the cost of wasting some
1951 // file space, by instead aligning to the start of a new
1952 // page. Here we use the real machine page size rather than
1953 // the ABI mandated page size.
1955 if (!are_addresses_set
&& aligned_addr
!= addr
)
1957 uint64_t first_off
= (common_pagesize
1959 & (common_pagesize
- 1)));
1960 uint64_t last_off
= new_addr
& (common_pagesize
- 1);
1963 && ((aligned_addr
& ~ (common_pagesize
- 1))
1964 != (new_addr
& ~ (common_pagesize
- 1)))
1965 && first_off
+ last_off
<= common_pagesize
)
1967 *pshndx
= shndx_hold
;
1968 addr
= align_address(aligned_addr
, common_pagesize
);
1969 addr
= align_address(addr
, (*p
)->maximum_alignment());
1970 off
= orig_off
+ ((addr
- orig_addr
) & (abi_pagesize
- 1));
1971 off
= align_file_offset(off
, addr
, abi_pagesize
);
1972 new_addr
= (*p
)->set_section_addresses(this, true, addr
,
1979 if (((*p
)->flags() & elfcpp::PF_W
) == 0)
1980 was_readonly
= true;
1982 // Implement --check-sections. We know that the segments
1983 // are sorted by LMA.
1984 if (check_sections
&& last_load_segment
!= NULL
)
1986 gold_assert(last_load_segment
->paddr() <= (*p
)->paddr());
1987 if (last_load_segment
->paddr() + last_load_segment
->memsz()
1990 unsigned long long lb1
= last_load_segment
->paddr();
1991 unsigned long long le1
= lb1
+ last_load_segment
->memsz();
1992 unsigned long long lb2
= (*p
)->paddr();
1993 unsigned long long le2
= lb2
+ (*p
)->memsz();
1994 gold_error(_("load segment overlap [0x%llx -> 0x%llx] and "
1995 "[0x%llx -> 0x%llx]"),
1996 lb1
, le1
, lb2
, le2
);
1999 last_load_segment
= *p
;
2003 // Handle the non-PT_LOAD segments, setting their offsets from their
2004 // section's offsets.
2005 for (Segment_list::iterator p
= this->segment_list_
.begin();
2006 p
!= this->segment_list_
.end();
2009 if ((*p
)->type() != elfcpp::PT_LOAD
)
2013 // Set the TLS offsets for each section in the PT_TLS segment.
2014 if (this->tls_segment_
!= NULL
)
2015 this->tls_segment_
->set_tls_offsets();
2020 // Set the offsets of all the allocated sections when doing a
2021 // relocatable link. This does the same jobs as set_segment_offsets,
2022 // only for a relocatable link.
2025 Layout::set_relocatable_section_offsets(Output_data
* file_header
,
2026 unsigned int *pshndx
)
2030 file_header
->set_address_and_file_offset(0, 0);
2031 off
+= file_header
->data_size();
2033 for (Section_list::iterator p
= this->section_list_
.begin();
2034 p
!= this->section_list_
.end();
2037 // We skip unallocated sections here, except that group sections
2038 // have to come first.
2039 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) == 0
2040 && (*p
)->type() != elfcpp::SHT_GROUP
)
2043 off
= align_address(off
, (*p
)->addralign());
2045 // The linker script might have set the address.
2046 if (!(*p
)->is_address_valid())
2047 (*p
)->set_address(0);
2048 (*p
)->set_file_offset(off
);
2049 (*p
)->finalize_data_size();
2050 off
+= (*p
)->data_size();
2052 (*p
)->set_out_shndx(*pshndx
);
2059 // Set the file offset of all the sections not associated with a
2063 Layout::set_section_offsets(off_t off
, Layout::Section_offset_pass pass
)
2065 for (Section_list::iterator p
= this->unattached_section_list_
.begin();
2066 p
!= this->unattached_section_list_
.end();
2069 // The symtab section is handled in create_symtab_sections.
2070 if (*p
== this->symtab_section_
)
2073 // If we've already set the data size, don't set it again.
2074 if ((*p
)->is_offset_valid() && (*p
)->is_data_size_valid())
2077 if (pass
== BEFORE_INPUT_SECTIONS_PASS
2078 && (*p
)->requires_postprocessing())
2080 (*p
)->create_postprocessing_buffer();
2081 this->any_postprocessing_sections_
= true;
2084 if (pass
== BEFORE_INPUT_SECTIONS_PASS
2085 && (*p
)->after_input_sections())
2087 else if (pass
== POSTPROCESSING_SECTIONS_PASS
2088 && (!(*p
)->after_input_sections()
2089 || (*p
)->type() == elfcpp::SHT_STRTAB
))
2091 else if (pass
== STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
2092 && (!(*p
)->after_input_sections()
2093 || (*p
)->type() != elfcpp::SHT_STRTAB
))
2096 off
= align_address(off
, (*p
)->addralign());
2097 (*p
)->set_file_offset(off
);
2098 (*p
)->finalize_data_size();
2099 off
+= (*p
)->data_size();
2101 // At this point the name must be set.
2102 if (pass
!= STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
)
2103 this->namepool_
.add((*p
)->name(), false, NULL
);
2108 // Set the section indexes of all the sections not associated with a
2112 Layout::set_section_indexes(unsigned int shndx
)
2114 for (Section_list::iterator p
= this->unattached_section_list_
.begin();
2115 p
!= this->unattached_section_list_
.end();
2118 if (!(*p
)->has_out_shndx())
2120 (*p
)->set_out_shndx(shndx
);
2127 // Set the section addresses according to the linker script. This is
2128 // only called when we see a SECTIONS clause. This returns the
2129 // program segment which should hold the file header and segment
2130 // headers, if any. It will return NULL if they should not be in a
2134 Layout::set_section_addresses_from_script(Symbol_table
* symtab
)
2136 Script_sections
* ss
= this->script_options_
->script_sections();
2137 gold_assert(ss
->saw_sections_clause());
2139 // Place each orphaned output section in the script.
2140 for (Section_list::iterator p
= this->section_list_
.begin();
2141 p
!= this->section_list_
.end();
2144 if (!(*p
)->found_in_sections_clause())
2145 ss
->place_orphan(*p
);
2148 return this->script_options_
->set_section_addresses(symtab
, this);
2151 // Count the local symbols in the regular symbol table and the dynamic
2152 // symbol table, and build the respective string pools.
2155 Layout::count_local_symbols(const Task
* task
,
2156 const Input_objects
* input_objects
)
2158 // First, figure out an upper bound on the number of symbols we'll
2159 // be inserting into each pool. This helps us create the pools with
2160 // the right size, to avoid unnecessary hashtable resizing.
2161 unsigned int symbol_count
= 0;
2162 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
2163 p
!= input_objects
->relobj_end();
2165 symbol_count
+= (*p
)->local_symbol_count();
2167 // Go from "upper bound" to "estimate." We overcount for two
2168 // reasons: we double-count symbols that occur in more than one
2169 // object file, and we count symbols that are dropped from the
2170 // output. Add it all together and assume we overcount by 100%.
2173 // We assume all symbols will go into both the sympool and dynpool.
2174 this->sympool_
.reserve(symbol_count
);
2175 this->dynpool_
.reserve(symbol_count
);
2177 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
2178 p
!= input_objects
->relobj_end();
2181 Task_lock_obj
<Object
> tlo(task
, *p
);
2182 (*p
)->count_local_symbols(&this->sympool_
, &this->dynpool_
);
2186 // Create the symbol table sections. Here we also set the final
2187 // values of the symbols. At this point all the loadable sections are
2188 // fully laid out. SHNUM is the number of sections so far.
2191 Layout::create_symtab_sections(const Input_objects
* input_objects
,
2192 Symbol_table
* symtab
,
2198 if (parameters
->target().get_size() == 32)
2200 symsize
= elfcpp::Elf_sizes
<32>::sym_size
;
2203 else if (parameters
->target().get_size() == 64)
2205 symsize
= elfcpp::Elf_sizes
<64>::sym_size
;
2212 off
= align_address(off
, align
);
2213 off_t startoff
= off
;
2215 // Save space for the dummy symbol at the start of the section. We
2216 // never bother to write this out--it will just be left as zero.
2218 unsigned int local_symbol_index
= 1;
2220 // Add STT_SECTION symbols for each Output section which needs one.
2221 for (Section_list::iterator p
= this->section_list_
.begin();
2222 p
!= this->section_list_
.end();
2225 if (!(*p
)->needs_symtab_index())
2226 (*p
)->set_symtab_index(-1U);
2229 (*p
)->set_symtab_index(local_symbol_index
);
2230 ++local_symbol_index
;
2235 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
2236 p
!= input_objects
->relobj_end();
2239 unsigned int index
= (*p
)->finalize_local_symbols(local_symbol_index
,
2241 off
+= (index
- local_symbol_index
) * symsize
;
2242 local_symbol_index
= index
;
2245 unsigned int local_symcount
= local_symbol_index
;
2246 gold_assert(local_symcount
* symsize
== off
- startoff
);
2249 size_t dyn_global_index
;
2251 if (this->dynsym_section_
== NULL
)
2254 dyn_global_index
= 0;
2259 dyn_global_index
= this->dynsym_section_
->info();
2260 off_t locsize
= dyn_global_index
* this->dynsym_section_
->entsize();
2261 dynoff
= this->dynsym_section_
->offset() + locsize
;
2262 dyncount
= (this->dynsym_section_
->data_size() - locsize
) / symsize
;
2263 gold_assert(static_cast<off_t
>(dyncount
* symsize
)
2264 == this->dynsym_section_
->data_size() - locsize
);
2267 off
= symtab
->finalize(off
, dynoff
, dyn_global_index
, dyncount
,
2268 &this->sympool_
, &local_symcount
);
2270 if (!parameters
->options().strip_all())
2272 this->sympool_
.set_string_offsets();
2274 const char* symtab_name
= this->namepool_
.add(".symtab", false, NULL
);
2275 Output_section
* osymtab
= this->make_output_section(symtab_name
,
2278 this->symtab_section_
= osymtab
;
2280 Output_section_data
* pos
= new Output_data_fixed_space(off
- startoff
,
2283 osymtab
->add_output_section_data(pos
);
2285 // We generate a .symtab_shndx section if we have more than
2286 // SHN_LORESERVE sections. Technically it is possible that we
2287 // don't need one, because it is possible that there are no
2288 // symbols in any of sections with indexes larger than
2289 // SHN_LORESERVE. That is probably unusual, though, and it is
2290 // easier to always create one than to compute section indexes
2291 // twice (once here, once when writing out the symbols).
2292 if (shnum
>= elfcpp::SHN_LORESERVE
)
2294 const char* symtab_xindex_name
= this->namepool_
.add(".symtab_shndx",
2296 Output_section
* osymtab_xindex
=
2297 this->make_output_section(symtab_xindex_name
,
2298 elfcpp::SHT_SYMTAB_SHNDX
, 0);
2300 size_t symcount
= (off
- startoff
) / symsize
;
2301 this->symtab_xindex_
= new Output_symtab_xindex(symcount
);
2303 osymtab_xindex
->add_output_section_data(this->symtab_xindex_
);
2305 osymtab_xindex
->set_link_section(osymtab
);
2306 osymtab_xindex
->set_addralign(4);
2307 osymtab_xindex
->set_entsize(4);
2309 osymtab_xindex
->set_after_input_sections();
2311 // This tells the driver code to wait until the symbol table
2312 // has written out before writing out the postprocessing
2313 // sections, including the .symtab_shndx section.
2314 this->any_postprocessing_sections_
= true;
2317 const char* strtab_name
= this->namepool_
.add(".strtab", false, NULL
);
2318 Output_section
* ostrtab
= this->make_output_section(strtab_name
,
2322 Output_section_data
* pstr
= new Output_data_strtab(&this->sympool_
);
2323 ostrtab
->add_output_section_data(pstr
);
2325 osymtab
->set_file_offset(startoff
);
2326 osymtab
->finalize_data_size();
2327 osymtab
->set_link_section(ostrtab
);
2328 osymtab
->set_info(local_symcount
);
2329 osymtab
->set_entsize(symsize
);
2335 // Create the .shstrtab section, which holds the names of the
2336 // sections. At the time this is called, we have created all the
2337 // output sections except .shstrtab itself.
2340 Layout::create_shstrtab()
2342 // FIXME: We don't need to create a .shstrtab section if we are
2343 // stripping everything.
2345 const char* name
= this->namepool_
.add(".shstrtab", false, NULL
);
2347 Output_section
* os
= this->make_output_section(name
, elfcpp::SHT_STRTAB
, 0);
2349 // We can't write out this section until we've set all the section
2350 // names, and we don't set the names of compressed output sections
2351 // until relocations are complete.
2352 os
->set_after_input_sections();
2354 Output_section_data
* posd
= new Output_data_strtab(&this->namepool_
);
2355 os
->add_output_section_data(posd
);
2360 // Create the section headers. SIZE is 32 or 64. OFF is the file
2364 Layout::create_shdrs(const Output_section
* shstrtab_section
, off_t
* poff
)
2366 Output_section_headers
* oshdrs
;
2367 oshdrs
= new Output_section_headers(this,
2368 &this->segment_list_
,
2369 &this->section_list_
,
2370 &this->unattached_section_list_
,
2373 off_t off
= align_address(*poff
, oshdrs
->addralign());
2374 oshdrs
->set_address_and_file_offset(0, off
);
2375 off
+= oshdrs
->data_size();
2377 this->section_headers_
= oshdrs
;
2380 // Count the allocated sections.
2383 Layout::allocated_output_section_count() const
2385 size_t section_count
= 0;
2386 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
2387 p
!= this->segment_list_
.end();
2389 section_count
+= (*p
)->output_section_count();
2390 return section_count
;
2393 // Create the dynamic symbol table.
2396 Layout::create_dynamic_symtab(const Input_objects
* input_objects
,
2397 Symbol_table
* symtab
,
2398 Output_section
**pdynstr
,
2399 unsigned int* plocal_dynamic_count
,
2400 std::vector
<Symbol
*>* pdynamic_symbols
,
2401 Versions
* pversions
)
2403 // Count all the symbols in the dynamic symbol table, and set the
2404 // dynamic symbol indexes.
2406 // Skip symbol 0, which is always all zeroes.
2407 unsigned int index
= 1;
2409 // Add STT_SECTION symbols for each Output section which needs one.
2410 for (Section_list::iterator p
= this->section_list_
.begin();
2411 p
!= this->section_list_
.end();
2414 if (!(*p
)->needs_dynsym_index())
2415 (*p
)->set_dynsym_index(-1U);
2418 (*p
)->set_dynsym_index(index
);
2423 // Count the local symbols that need to go in the dynamic symbol table,
2424 // and set the dynamic symbol indexes.
2425 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
2426 p
!= input_objects
->relobj_end();
2429 unsigned int new_index
= (*p
)->set_local_dynsym_indexes(index
);
2433 unsigned int local_symcount
= index
;
2434 *plocal_dynamic_count
= local_symcount
;
2436 index
= symtab
->set_dynsym_indexes(index
, pdynamic_symbols
,
2437 &this->dynpool_
, pversions
);
2441 const int size
= parameters
->target().get_size();
2444 symsize
= elfcpp::Elf_sizes
<32>::sym_size
;
2447 else if (size
== 64)
2449 symsize
= elfcpp::Elf_sizes
<64>::sym_size
;
2455 // Create the dynamic symbol table section.
2457 Output_section
* dynsym
= this->choose_output_section(NULL
, ".dynsym",
2462 Output_section_data
* odata
= new Output_data_fixed_space(index
* symsize
,
2465 dynsym
->add_output_section_data(odata
);
2467 dynsym
->set_info(local_symcount
);
2468 dynsym
->set_entsize(symsize
);
2469 dynsym
->set_addralign(align
);
2471 this->dynsym_section_
= dynsym
;
2473 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
2474 odyn
->add_section_address(elfcpp::DT_SYMTAB
, dynsym
);
2475 odyn
->add_constant(elfcpp::DT_SYMENT
, symsize
);
2477 // If there are more than SHN_LORESERVE allocated sections, we
2478 // create a .dynsym_shndx section. It is possible that we don't
2479 // need one, because it is possible that there are no dynamic
2480 // symbols in any of the sections with indexes larger than
2481 // SHN_LORESERVE. This is probably unusual, though, and at this
2482 // time we don't know the actual section indexes so it is
2483 // inconvenient to check.
2484 if (this->allocated_output_section_count() >= elfcpp::SHN_LORESERVE
)
2486 Output_section
* dynsym_xindex
=
2487 this->choose_output_section(NULL
, ".dynsym_shndx",
2488 elfcpp::SHT_SYMTAB_SHNDX
,
2492 this->dynsym_xindex_
= new Output_symtab_xindex(index
);
2494 dynsym_xindex
->add_output_section_data(this->dynsym_xindex_
);
2496 dynsym_xindex
->set_link_section(dynsym
);
2497 dynsym_xindex
->set_addralign(4);
2498 dynsym_xindex
->set_entsize(4);
2500 dynsym_xindex
->set_after_input_sections();
2502 // This tells the driver code to wait until the symbol table has
2503 // written out before writing out the postprocessing sections,
2504 // including the .dynsym_shndx section.
2505 this->any_postprocessing_sections_
= true;
2508 // Create the dynamic string table section.
2510 Output_section
* dynstr
= this->choose_output_section(NULL
, ".dynstr",
2515 Output_section_data
* strdata
= new Output_data_strtab(&this->dynpool_
);
2516 dynstr
->add_output_section_data(strdata
);
2518 dynsym
->set_link_section(dynstr
);
2519 this->dynamic_section_
->set_link_section(dynstr
);
2521 odyn
->add_section_address(elfcpp::DT_STRTAB
, dynstr
);
2522 odyn
->add_section_size(elfcpp::DT_STRSZ
, dynstr
);
2526 // Create the hash tables.
2528 if (strcmp(parameters
->options().hash_style(), "sysv") == 0
2529 || strcmp(parameters
->options().hash_style(), "both") == 0)
2531 unsigned char* phash
;
2532 unsigned int hashlen
;
2533 Dynobj::create_elf_hash_table(*pdynamic_symbols
, local_symcount
,
2536 Output_section
* hashsec
= this->choose_output_section(NULL
, ".hash",
2541 Output_section_data
* hashdata
= new Output_data_const_buffer(phash
,
2545 hashsec
->add_output_section_data(hashdata
);
2547 hashsec
->set_link_section(dynsym
);
2548 hashsec
->set_entsize(4);
2550 odyn
->add_section_address(elfcpp::DT_HASH
, hashsec
);
2553 if (strcmp(parameters
->options().hash_style(), "gnu") == 0
2554 || strcmp(parameters
->options().hash_style(), "both") == 0)
2556 unsigned char* phash
;
2557 unsigned int hashlen
;
2558 Dynobj::create_gnu_hash_table(*pdynamic_symbols
, local_symcount
,
2561 Output_section
* hashsec
= this->choose_output_section(NULL
, ".gnu.hash",
2562 elfcpp::SHT_GNU_HASH
,
2566 Output_section_data
* hashdata
= new Output_data_const_buffer(phash
,
2570 hashsec
->add_output_section_data(hashdata
);
2572 hashsec
->set_link_section(dynsym
);
2573 hashsec
->set_entsize(4);
2575 odyn
->add_section_address(elfcpp::DT_GNU_HASH
, hashsec
);
2579 // Assign offsets to each local portion of the dynamic symbol table.
2582 Layout::assign_local_dynsym_offsets(const Input_objects
* input_objects
)
2584 Output_section
* dynsym
= this->dynsym_section_
;
2585 gold_assert(dynsym
!= NULL
);
2587 off_t off
= dynsym
->offset();
2589 // Skip the dummy symbol at the start of the section.
2590 off
+= dynsym
->entsize();
2592 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
2593 p
!= input_objects
->relobj_end();
2596 unsigned int count
= (*p
)->set_local_dynsym_offset(off
);
2597 off
+= count
* dynsym
->entsize();
2601 // Create the version sections.
2604 Layout::create_version_sections(const Versions
* versions
,
2605 const Symbol_table
* symtab
,
2606 unsigned int local_symcount
,
2607 const std::vector
<Symbol
*>& dynamic_symbols
,
2608 const Output_section
* dynstr
)
2610 if (!versions
->any_defs() && !versions
->any_needs())
2613 switch (parameters
->size_and_endianness())
2615 #ifdef HAVE_TARGET_32_LITTLE
2616 case Parameters::TARGET_32_LITTLE
:
2617 this->sized_create_version_sections
<32, false>(versions
, symtab
,
2619 dynamic_symbols
, dynstr
);
2622 #ifdef HAVE_TARGET_32_BIG
2623 case Parameters::TARGET_32_BIG
:
2624 this->sized_create_version_sections
<32, true>(versions
, symtab
,
2626 dynamic_symbols
, dynstr
);
2629 #ifdef HAVE_TARGET_64_LITTLE
2630 case Parameters::TARGET_64_LITTLE
:
2631 this->sized_create_version_sections
<64, false>(versions
, symtab
,
2633 dynamic_symbols
, dynstr
);
2636 #ifdef HAVE_TARGET_64_BIG
2637 case Parameters::TARGET_64_BIG
:
2638 this->sized_create_version_sections
<64, true>(versions
, symtab
,
2640 dynamic_symbols
, dynstr
);
2648 // Create the version sections, sized version.
2650 template<int size
, bool big_endian
>
2652 Layout::sized_create_version_sections(
2653 const Versions
* versions
,
2654 const Symbol_table
* symtab
,
2655 unsigned int local_symcount
,
2656 const std::vector
<Symbol
*>& dynamic_symbols
,
2657 const Output_section
* dynstr
)
2659 Output_section
* vsec
= this->choose_output_section(NULL
, ".gnu.version",
2660 elfcpp::SHT_GNU_versym
,
2664 unsigned char* vbuf
;
2666 versions
->symbol_section_contents
<size
, big_endian
>(symtab
, &this->dynpool_
,
2671 Output_section_data
* vdata
= new Output_data_const_buffer(vbuf
, vsize
, 2,
2674 vsec
->add_output_section_data(vdata
);
2675 vsec
->set_entsize(2);
2676 vsec
->set_link_section(this->dynsym_section_
);
2678 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
2679 odyn
->add_section_address(elfcpp::DT_VERSYM
, vsec
);
2681 if (versions
->any_defs())
2683 Output_section
* vdsec
;
2684 vdsec
= this->choose_output_section(NULL
, ".gnu.version_d",
2685 elfcpp::SHT_GNU_verdef
,
2689 unsigned char* vdbuf
;
2690 unsigned int vdsize
;
2691 unsigned int vdentries
;
2692 versions
->def_section_contents
<size
, big_endian
>(&this->dynpool_
, &vdbuf
,
2693 &vdsize
, &vdentries
);
2695 Output_section_data
* vddata
=
2696 new Output_data_const_buffer(vdbuf
, vdsize
, 4, "** version defs");
2698 vdsec
->add_output_section_data(vddata
);
2699 vdsec
->set_link_section(dynstr
);
2700 vdsec
->set_info(vdentries
);
2702 odyn
->add_section_address(elfcpp::DT_VERDEF
, vdsec
);
2703 odyn
->add_constant(elfcpp::DT_VERDEFNUM
, vdentries
);
2706 if (versions
->any_needs())
2708 Output_section
* vnsec
;
2709 vnsec
= this->choose_output_section(NULL
, ".gnu.version_r",
2710 elfcpp::SHT_GNU_verneed
,
2714 unsigned char* vnbuf
;
2715 unsigned int vnsize
;
2716 unsigned int vnentries
;
2717 versions
->need_section_contents
<size
, big_endian
>(&this->dynpool_
,
2721 Output_section_data
* vndata
=
2722 new Output_data_const_buffer(vnbuf
, vnsize
, 4, "** version refs");
2724 vnsec
->add_output_section_data(vndata
);
2725 vnsec
->set_link_section(dynstr
);
2726 vnsec
->set_info(vnentries
);
2728 odyn
->add_section_address(elfcpp::DT_VERNEED
, vnsec
);
2729 odyn
->add_constant(elfcpp::DT_VERNEEDNUM
, vnentries
);
2733 // Create the .interp section and PT_INTERP segment.
2736 Layout::create_interp(const Target
* target
)
2738 const char* interp
= parameters
->options().dynamic_linker();
2741 interp
= target
->dynamic_linker();
2742 gold_assert(interp
!= NULL
);
2745 size_t len
= strlen(interp
) + 1;
2747 Output_section_data
* odata
= new Output_data_const(interp
, len
, 1);
2749 Output_section
* osec
= this->choose_output_section(NULL
, ".interp",
2750 elfcpp::SHT_PROGBITS
,
2753 osec
->add_output_section_data(odata
);
2755 if (!this->script_options_
->saw_phdrs_clause())
2757 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_INTERP
,
2759 oseg
->add_output_section(osec
, elfcpp::PF_R
);
2763 // Finish the .dynamic section and PT_DYNAMIC segment.
2766 Layout::finish_dynamic_section(const Input_objects
* input_objects
,
2767 const Symbol_table
* symtab
)
2769 if (!this->script_options_
->saw_phdrs_clause())
2771 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_DYNAMIC
,
2774 oseg
->add_output_section(this->dynamic_section_
,
2775 elfcpp::PF_R
| elfcpp::PF_W
);
2778 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
2780 for (Input_objects::Dynobj_iterator p
= input_objects
->dynobj_begin();
2781 p
!= input_objects
->dynobj_end();
2784 // FIXME: Handle --as-needed.
2785 odyn
->add_string(elfcpp::DT_NEEDED
, (*p
)->soname());
2788 if (parameters
->options().shared())
2790 const char* soname
= parameters
->options().soname();
2792 odyn
->add_string(elfcpp::DT_SONAME
, soname
);
2795 // FIXME: Support --init and --fini.
2796 Symbol
* sym
= symtab
->lookup("_init");
2797 if (sym
!= NULL
&& sym
->is_defined() && !sym
->is_from_dynobj())
2798 odyn
->add_symbol(elfcpp::DT_INIT
, sym
);
2800 sym
= symtab
->lookup("_fini");
2801 if (sym
!= NULL
&& sym
->is_defined() && !sym
->is_from_dynobj())
2802 odyn
->add_symbol(elfcpp::DT_FINI
, sym
);
2804 // FIXME: Support DT_INIT_ARRAY and DT_FINI_ARRAY.
2806 // Add a DT_RPATH entry if needed.
2807 const General_options::Dir_list
& rpath(parameters
->options().rpath());
2810 std::string rpath_val
;
2811 for (General_options::Dir_list::const_iterator p
= rpath
.begin();
2815 if (rpath_val
.empty())
2816 rpath_val
= p
->name();
2819 // Eliminate duplicates.
2820 General_options::Dir_list::const_iterator q
;
2821 for (q
= rpath
.begin(); q
!= p
; ++q
)
2822 if (q
->name() == p
->name())
2827 rpath_val
+= p
->name();
2832 odyn
->add_string(elfcpp::DT_RPATH
, rpath_val
);
2833 if (parameters
->options().enable_new_dtags())
2834 odyn
->add_string(elfcpp::DT_RUNPATH
, rpath_val
);
2837 // Look for text segments that have dynamic relocations.
2838 bool have_textrel
= false;
2839 if (!this->script_options_
->saw_sections_clause())
2841 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
2842 p
!= this->segment_list_
.end();
2845 if (((*p
)->flags() & elfcpp::PF_W
) == 0
2846 && (*p
)->dynamic_reloc_count() > 0)
2848 have_textrel
= true;
2855 // We don't know the section -> segment mapping, so we are
2856 // conservative and just look for readonly sections with
2857 // relocations. If those sections wind up in writable segments,
2858 // then we have created an unnecessary DT_TEXTREL entry.
2859 for (Section_list::const_iterator p
= this->section_list_
.begin();
2860 p
!= this->section_list_
.end();
2863 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) != 0
2864 && ((*p
)->flags() & elfcpp::SHF_WRITE
) == 0
2865 && ((*p
)->dynamic_reloc_count() > 0))
2867 have_textrel
= true;
2873 // Add a DT_FLAGS entry. We add it even if no flags are set so that
2874 // post-link tools can easily modify these flags if desired.
2875 unsigned int flags
= 0;
2878 // Add a DT_TEXTREL for compatibility with older loaders.
2879 odyn
->add_constant(elfcpp::DT_TEXTREL
, 0);
2880 flags
|= elfcpp::DF_TEXTREL
;
2882 if (parameters
->options().shared() && this->has_static_tls())
2883 flags
|= elfcpp::DF_STATIC_TLS
;
2884 if (parameters
->options().origin())
2885 flags
|= elfcpp::DF_ORIGIN
;
2886 if (parameters
->options().now())
2887 flags
|= elfcpp::DF_BIND_NOW
;
2888 odyn
->add_constant(elfcpp::DT_FLAGS
, flags
);
2891 if (parameters
->options().initfirst())
2892 flags
|= elfcpp::DF_1_INITFIRST
;
2893 if (parameters
->options().interpose())
2894 flags
|= elfcpp::DF_1_INTERPOSE
;
2895 if (parameters
->options().loadfltr())
2896 flags
|= elfcpp::DF_1_LOADFLTR
;
2897 if (parameters
->options().nodefaultlib())
2898 flags
|= elfcpp::DF_1_NODEFLIB
;
2899 if (parameters
->options().nodelete())
2900 flags
|= elfcpp::DF_1_NODELETE
;
2901 if (parameters
->options().nodlopen())
2902 flags
|= elfcpp::DF_1_NOOPEN
;
2903 if (parameters
->options().nodump())
2904 flags
|= elfcpp::DF_1_NODUMP
;
2905 if (!parameters
->options().shared())
2906 flags
&= ~(elfcpp::DF_1_INITFIRST
2907 | elfcpp::DF_1_NODELETE
2908 | elfcpp::DF_1_NOOPEN
);
2909 if (parameters
->options().origin())
2910 flags
|= elfcpp::DF_1_ORIGIN
;
2911 if (parameters
->options().now())
2912 flags
|= elfcpp::DF_1_NOW
;
2914 odyn
->add_constant(elfcpp::DT_FLAGS_1
, flags
);
2917 // The mapping of input section name prefixes to output section names.
2918 // In some cases one prefix is itself a prefix of another prefix; in
2919 // such a case the longer prefix must come first. These prefixes are
2920 // based on the GNU linker default ELF linker script.
2922 #define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 }
2923 const Layout::Section_name_mapping
Layout::section_name_mapping
[] =
2925 MAPPING_INIT(".text.", ".text"),
2926 MAPPING_INIT(".ctors.", ".ctors"),
2927 MAPPING_INIT(".dtors.", ".dtors"),
2928 MAPPING_INIT(".rodata.", ".rodata"),
2929 MAPPING_INIT(".data.rel.ro.local", ".data.rel.ro.local"),
2930 MAPPING_INIT(".data.rel.ro", ".data.rel.ro"),
2931 MAPPING_INIT(".data.", ".data"),
2932 MAPPING_INIT(".bss.", ".bss"),
2933 MAPPING_INIT(".tdata.", ".tdata"),
2934 MAPPING_INIT(".tbss.", ".tbss"),
2935 MAPPING_INIT(".init_array.", ".init_array"),
2936 MAPPING_INIT(".fini_array.", ".fini_array"),
2937 MAPPING_INIT(".sdata.", ".sdata"),
2938 MAPPING_INIT(".sbss.", ".sbss"),
2939 // FIXME: In the GNU linker, .sbss2 and .sdata2 are handled
2940 // differently depending on whether it is creating a shared library.
2941 MAPPING_INIT(".sdata2.", ".sdata"),
2942 MAPPING_INIT(".sbss2.", ".sbss"),
2943 MAPPING_INIT(".lrodata.", ".lrodata"),
2944 MAPPING_INIT(".ldata.", ".ldata"),
2945 MAPPING_INIT(".lbss.", ".lbss"),
2946 MAPPING_INIT(".gcc_except_table.", ".gcc_except_table"),
2947 MAPPING_INIT(".gnu.linkonce.d.rel.ro.local.", ".data.rel.ro.local"),
2948 MAPPING_INIT(".gnu.linkonce.d.rel.ro.", ".data.rel.ro"),
2949 MAPPING_INIT(".gnu.linkonce.t.", ".text"),
2950 MAPPING_INIT(".gnu.linkonce.r.", ".rodata"),
2951 MAPPING_INIT(".gnu.linkonce.d.", ".data"),
2952 MAPPING_INIT(".gnu.linkonce.b.", ".bss"),
2953 MAPPING_INIT(".gnu.linkonce.s.", ".sdata"),
2954 MAPPING_INIT(".gnu.linkonce.sb.", ".sbss"),
2955 MAPPING_INIT(".gnu.linkonce.s2.", ".sdata"),
2956 MAPPING_INIT(".gnu.linkonce.sb2.", ".sbss"),
2957 MAPPING_INIT(".gnu.linkonce.wi.", ".debug_info"),
2958 MAPPING_INIT(".gnu.linkonce.td.", ".tdata"),
2959 MAPPING_INIT(".gnu.linkonce.tb.", ".tbss"),
2960 MAPPING_INIT(".gnu.linkonce.lr.", ".lrodata"),
2961 MAPPING_INIT(".gnu.linkonce.l.", ".ldata"),
2962 MAPPING_INIT(".gnu.linkonce.lb.", ".lbss"),
2963 MAPPING_INIT(".ARM.extab.", ".ARM.extab"),
2964 MAPPING_INIT(".gnu.linkonce.armextab.", ".ARM.extab"),
2965 MAPPING_INIT(".ARM.exidx.", ".ARM.exidx"),
2966 MAPPING_INIT(".gnu.linkonce.armexidx.", ".ARM.exidx"),
2970 const int Layout::section_name_mapping_count
=
2971 (sizeof(Layout::section_name_mapping
)
2972 / sizeof(Layout::section_name_mapping
[0]));
2974 // Choose the output section name to use given an input section name.
2975 // Set *PLEN to the length of the name. *PLEN is initialized to the
2979 Layout::output_section_name(const char* name
, size_t* plen
)
2981 // gcc 4.3 generates the following sorts of section names when it
2982 // needs a section name specific to a function:
2988 // .data.rel.local.FN
2990 // .data.rel.ro.local.FN
2997 // The GNU linker maps all of those to the part before the .FN,
2998 // except that .data.rel.local.FN is mapped to .data, and
2999 // .data.rel.ro.local.FN is mapped to .data.rel.ro. The sections
3000 // beginning with .data.rel.ro.local are grouped together.
3002 // For an anonymous namespace, the string FN can contain a '.'.
3004 // Also of interest: .rodata.strN.N, .rodata.cstN, both of which the
3005 // GNU linker maps to .rodata.
3007 // The .data.rel.ro sections are used with -z relro. The sections
3008 // are recognized by name. We use the same names that the GNU
3009 // linker does for these sections.
3011 // It is hard to handle this in a principled way, so we don't even
3012 // try. We use a table of mappings. If the input section name is
3013 // not found in the table, we simply use it as the output section
3016 const Section_name_mapping
* psnm
= section_name_mapping
;
3017 for (int i
= 0; i
< section_name_mapping_count
; ++i
, ++psnm
)
3019 if (strncmp(name
, psnm
->from
, psnm
->fromlen
) == 0)
3021 *plen
= psnm
->tolen
;
3029 // Check if a comdat group or .gnu.linkonce section with the given
3030 // NAME is selected for the link. If there is already a section,
3031 // *KEPT_SECTION is set to point to the signature and the function
3032 // returns false. Otherwise, the CANDIDATE signature is recorded for
3033 // this NAME in the layout object, *KEPT_SECTION is set to the
3034 // internal copy and the function return false. In some cases, with
3035 // CANDIDATE->GROUP_ being false, KEPT_SECTION can point back to
3039 Layout::find_or_add_kept_section(const std::string
& name
,
3040 Kept_section
* candidate
,
3041 Kept_section
** kept_section
)
3043 // It's normal to see a couple of entries here, for the x86 thunk
3044 // sections. If we see more than a few, we're linking a C++
3045 // program, and we resize to get more space to minimize rehashing.
3046 if (this->signatures_
.size() > 4
3047 && !this->resized_signatures_
)
3049 reserve_unordered_map(&this->signatures_
,
3050 this->number_of_input_files_
* 64);
3051 this->resized_signatures_
= true;
3054 std::pair
<Signatures::iterator
, bool> ins(
3055 this->signatures_
.insert(std::make_pair(name
, *candidate
)));
3058 *kept_section
= &ins
.first
->second
;
3061 // This is the first time we've seen this signature.
3065 if (ins
.first
->second
.is_group
)
3067 // We've already seen a real section group with this signature.
3068 // If the kept group is from a plugin object, and we're in
3069 // the replacement phase, accept the new one as a replacement.
3070 if (ins
.first
->second
.object
== NULL
3071 && parameters
->options().plugins()->in_replacement_phase())
3073 ins
.first
->second
= *candidate
;
3078 else if (candidate
->is_group
)
3080 // This is a real section group, and we've already seen a
3081 // linkonce section with this signature. Record that we've seen
3082 // a section group, and don't include this section group.
3083 ins
.first
->second
.is_group
= true;
3088 // We've already seen a linkonce section and this is a linkonce
3089 // section. These don't block each other--this may be the same
3090 // symbol name with different section types.
3091 *kept_section
= candidate
;
3096 // Find the given comdat signature, and return the object and section
3097 // index of the kept group.
3099 Layout::find_kept_object(const std::string
& signature
,
3100 unsigned int* pshndx
) const
3102 Signatures::const_iterator p
= this->signatures_
.find(signature
);
3103 if (p
== this->signatures_
.end())
3106 *pshndx
= p
->second
.shndx
;
3107 return p
->second
.object
;
3110 // Store the allocated sections into the section list.
3113 Layout::get_allocated_sections(Section_list
* section_list
) const
3115 for (Section_list::const_iterator p
= this->section_list_
.begin();
3116 p
!= this->section_list_
.end();
3118 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) != 0)
3119 section_list
->push_back(*p
);
3122 // Create an output segment.
3125 Layout::make_output_segment(elfcpp::Elf_Word type
, elfcpp::Elf_Word flags
)
3127 gold_assert(!parameters
->options().relocatable());
3128 Output_segment
* oseg
= new Output_segment(type
, flags
);
3129 this->segment_list_
.push_back(oseg
);
3131 if (type
== elfcpp::PT_TLS
)
3132 this->tls_segment_
= oseg
;
3133 else if (type
== elfcpp::PT_GNU_RELRO
)
3134 this->relro_segment_
= oseg
;
3139 // Write out the Output_sections. Most won't have anything to write,
3140 // since most of the data will come from input sections which are
3141 // handled elsewhere. But some Output_sections do have Output_data.
3144 Layout::write_output_sections(Output_file
* of
) const
3146 for (Section_list::const_iterator p
= this->section_list_
.begin();
3147 p
!= this->section_list_
.end();
3150 if (!(*p
)->after_input_sections())
3155 // Write out data not associated with a section or the symbol table.
3158 Layout::write_data(const Symbol_table
* symtab
, Output_file
* of
) const
3160 if (!parameters
->options().strip_all())
3162 const Output_section
* symtab_section
= this->symtab_section_
;
3163 for (Section_list::const_iterator p
= this->section_list_
.begin();
3164 p
!= this->section_list_
.end();
3167 if ((*p
)->needs_symtab_index())
3169 gold_assert(symtab_section
!= NULL
);
3170 unsigned int index
= (*p
)->symtab_index();
3171 gold_assert(index
> 0 && index
!= -1U);
3172 off_t off
= (symtab_section
->offset()
3173 + index
* symtab_section
->entsize());
3174 symtab
->write_section_symbol(*p
, this->symtab_xindex_
, of
, off
);
3179 const Output_section
* dynsym_section
= this->dynsym_section_
;
3180 for (Section_list::const_iterator p
= this->section_list_
.begin();
3181 p
!= this->section_list_
.end();
3184 if ((*p
)->needs_dynsym_index())
3186 gold_assert(dynsym_section
!= NULL
);
3187 unsigned int index
= (*p
)->dynsym_index();
3188 gold_assert(index
> 0 && index
!= -1U);
3189 off_t off
= (dynsym_section
->offset()
3190 + index
* dynsym_section
->entsize());
3191 symtab
->write_section_symbol(*p
, this->dynsym_xindex_
, of
, off
);
3195 // Write out the Output_data which are not in an Output_section.
3196 for (Data_list::const_iterator p
= this->special_output_list_
.begin();
3197 p
!= this->special_output_list_
.end();
3202 // Write out the Output_sections which can only be written after the
3203 // input sections are complete.
3206 Layout::write_sections_after_input_sections(Output_file
* of
)
3208 // Determine the final section offsets, and thus the final output
3209 // file size. Note we finalize the .shstrab last, to allow the
3210 // after_input_section sections to modify their section-names before
3212 if (this->any_postprocessing_sections_
)
3214 off_t off
= this->output_file_size_
;
3215 off
= this->set_section_offsets(off
, POSTPROCESSING_SECTIONS_PASS
);
3217 // Now that we've finalized the names, we can finalize the shstrab.
3219 this->set_section_offsets(off
,
3220 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
);
3222 if (off
> this->output_file_size_
)
3225 this->output_file_size_
= off
;
3229 for (Section_list::const_iterator p
= this->section_list_
.begin();
3230 p
!= this->section_list_
.end();
3233 if ((*p
)->after_input_sections())
3237 this->section_headers_
->write(of
);
3240 // If the build ID requires computing a checksum, do so here, and
3241 // write it out. We compute a checksum over the entire file because
3242 // that is simplest.
3245 Layout::write_build_id(Output_file
* of
) const
3247 if (this->build_id_note_
== NULL
)
3250 const unsigned char* iv
= of
->get_input_view(0, this->output_file_size_
);
3252 unsigned char* ov
= of
->get_output_view(this->build_id_note_
->offset(),
3253 this->build_id_note_
->data_size());
3255 const char* style
= parameters
->options().build_id();
3256 if (strcmp(style
, "sha1") == 0)
3259 sha1_init_ctx(&ctx
);
3260 sha1_process_bytes(iv
, this->output_file_size_
, &ctx
);
3261 sha1_finish_ctx(&ctx
, ov
);
3263 else if (strcmp(style
, "md5") == 0)
3267 md5_process_bytes(iv
, this->output_file_size_
, &ctx
);
3268 md5_finish_ctx(&ctx
, ov
);
3273 of
->write_output_view(this->build_id_note_
->offset(),
3274 this->build_id_note_
->data_size(),
3277 of
->free_input_view(0, this->output_file_size_
, iv
);
3280 // Write out a binary file. This is called after the link is
3281 // complete. IN is the temporary output file we used to generate the
3282 // ELF code. We simply walk through the segments, read them from
3283 // their file offset in IN, and write them to their load address in
3284 // the output file. FIXME: with a bit more work, we could support
3285 // S-records and/or Intel hex format here.
3288 Layout::write_binary(Output_file
* in
) const
3290 gold_assert(parameters
->options().oformat_enum()
3291 == General_options::OBJECT_FORMAT_BINARY
);
3293 // Get the size of the binary file.
3294 uint64_t max_load_address
= 0;
3295 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
3296 p
!= this->segment_list_
.end();
3299 if ((*p
)->type() == elfcpp::PT_LOAD
&& (*p
)->filesz() > 0)
3301 uint64_t max_paddr
= (*p
)->paddr() + (*p
)->filesz();
3302 if (max_paddr
> max_load_address
)
3303 max_load_address
= max_paddr
;
3307 Output_file
out(parameters
->options().output_file_name());
3308 out
.open(max_load_address
);
3310 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
3311 p
!= this->segment_list_
.end();
3314 if ((*p
)->type() == elfcpp::PT_LOAD
&& (*p
)->filesz() > 0)
3316 const unsigned char* vin
= in
->get_input_view((*p
)->offset(),
3318 unsigned char* vout
= out
.get_output_view((*p
)->paddr(),
3320 memcpy(vout
, vin
, (*p
)->filesz());
3321 out
.write_output_view((*p
)->paddr(), (*p
)->filesz(), vout
);
3322 in
->free_input_view((*p
)->offset(), (*p
)->filesz(), vin
);
3329 // Print the output sections to the map file.
3332 Layout::print_to_mapfile(Mapfile
* mapfile
) const
3334 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
3335 p
!= this->segment_list_
.end();
3337 (*p
)->print_sections_to_mapfile(mapfile
);
3340 // Print statistical information to stderr. This is used for --stats.
3343 Layout::print_stats() const
3345 this->namepool_
.print_stats("section name pool");
3346 this->sympool_
.print_stats("output symbol name pool");
3347 this->dynpool_
.print_stats("dynamic name pool");
3349 for (Section_list::const_iterator p
= this->section_list_
.begin();
3350 p
!= this->section_list_
.end();
3352 (*p
)->print_merge_stats();
3355 // Write_sections_task methods.
3357 // We can always run this task.
3360 Write_sections_task::is_runnable()
3365 // We need to unlock both OUTPUT_SECTIONS_BLOCKER and FINAL_BLOCKER
3369 Write_sections_task::locks(Task_locker
* tl
)
3371 tl
->add(this, this->output_sections_blocker_
);
3372 tl
->add(this, this->final_blocker_
);
3375 // Run the task--write out the data.
3378 Write_sections_task::run(Workqueue
*)
3380 this->layout_
->write_output_sections(this->of_
);
3383 // Write_data_task methods.
3385 // We can always run this task.
3388 Write_data_task::is_runnable()
3393 // We need to unlock FINAL_BLOCKER when finished.
3396 Write_data_task::locks(Task_locker
* tl
)
3398 tl
->add(this, this->final_blocker_
);
3401 // Run the task--write out the data.
3404 Write_data_task::run(Workqueue
*)
3406 this->layout_
->write_data(this->symtab_
, this->of_
);
3409 // Write_symbols_task methods.
3411 // We can always run this task.
3414 Write_symbols_task::is_runnable()
3419 // We need to unlock FINAL_BLOCKER when finished.
3422 Write_symbols_task::locks(Task_locker
* tl
)
3424 tl
->add(this, this->final_blocker_
);
3427 // Run the task--write out the symbols.
3430 Write_symbols_task::run(Workqueue
*)
3432 this->symtab_
->write_globals(this->sympool_
, this->dynpool_
,
3433 this->layout_
->symtab_xindex(),
3434 this->layout_
->dynsym_xindex(), this->of_
);
3437 // Write_after_input_sections_task methods.
3439 // We can only run this task after the input sections have completed.
3442 Write_after_input_sections_task::is_runnable()
3444 if (this->input_sections_blocker_
->is_blocked())
3445 return this->input_sections_blocker_
;
3449 // We need to unlock FINAL_BLOCKER when finished.
3452 Write_after_input_sections_task::locks(Task_locker
* tl
)
3454 tl
->add(this, this->final_blocker_
);
3460 Write_after_input_sections_task::run(Workqueue
*)
3462 this->layout_
->write_sections_after_input_sections(this->of_
);
3465 // Close_task_runner methods.
3467 // Run the task--close the file.
3470 Close_task_runner::run(Workqueue
*, const Task
*)
3472 // If we need to compute a checksum for the BUILD if, we do so here.
3473 this->layout_
->write_build_id(this->of_
);
3475 // If we've been asked to create a binary file, we do so here.
3476 if (this->options_
->oformat_enum() != General_options::OBJECT_FORMAT_ELF
)
3477 this->layout_
->write_binary(this->of_
);
3482 // Instantiate the templates we need. We could use the configure
3483 // script to restrict this to only the ones for implemented targets.
3485 #ifdef HAVE_TARGET_32_LITTLE
3488 Layout::layout
<32, false>(Sized_relobj
<32, false>* object
, unsigned int shndx
,
3490 const elfcpp::Shdr
<32, false>& shdr
,
3491 unsigned int, unsigned int, off_t
*);
3494 #ifdef HAVE_TARGET_32_BIG
3497 Layout::layout
<32, true>(Sized_relobj
<32, true>* object
, unsigned int shndx
,
3499 const elfcpp::Shdr
<32, true>& shdr
,
3500 unsigned int, unsigned int, off_t
*);
3503 #ifdef HAVE_TARGET_64_LITTLE
3506 Layout::layout
<64, false>(Sized_relobj
<64, false>* object
, unsigned int shndx
,
3508 const elfcpp::Shdr
<64, false>& shdr
,
3509 unsigned int, unsigned int, off_t
*);
3512 #ifdef HAVE_TARGET_64_BIG
3515 Layout::layout
<64, true>(Sized_relobj
<64, true>* object
, unsigned int shndx
,
3517 const elfcpp::Shdr
<64, true>& shdr
,
3518 unsigned int, unsigned int, off_t
*);
3521 #ifdef HAVE_TARGET_32_LITTLE
3524 Layout::layout_reloc
<32, false>(Sized_relobj
<32, false>* object
,
3525 unsigned int reloc_shndx
,
3526 const elfcpp::Shdr
<32, false>& shdr
,
3527 Output_section
* data_section
,
3528 Relocatable_relocs
* rr
);
3531 #ifdef HAVE_TARGET_32_BIG
3534 Layout::layout_reloc
<32, true>(Sized_relobj
<32, true>* object
,
3535 unsigned int reloc_shndx
,
3536 const elfcpp::Shdr
<32, true>& shdr
,
3537 Output_section
* data_section
,
3538 Relocatable_relocs
* rr
);
3541 #ifdef HAVE_TARGET_64_LITTLE
3544 Layout::layout_reloc
<64, false>(Sized_relobj
<64, false>* object
,
3545 unsigned int reloc_shndx
,
3546 const elfcpp::Shdr
<64, false>& shdr
,
3547 Output_section
* data_section
,
3548 Relocatable_relocs
* rr
);
3551 #ifdef HAVE_TARGET_64_BIG
3554 Layout::layout_reloc
<64, true>(Sized_relobj
<64, true>* object
,
3555 unsigned int reloc_shndx
,
3556 const elfcpp::Shdr
<64, true>& shdr
,
3557 Output_section
* data_section
,
3558 Relocatable_relocs
* rr
);
3561 #ifdef HAVE_TARGET_32_LITTLE
3564 Layout::layout_group
<32, false>(Symbol_table
* symtab
,
3565 Sized_relobj
<32, false>* object
,
3567 const char* group_section_name
,
3568 const char* signature
,
3569 const elfcpp::Shdr
<32, false>& shdr
,
3570 elfcpp::Elf_Word flags
,
3571 std::vector
<unsigned int>* shndxes
);
3574 #ifdef HAVE_TARGET_32_BIG
3577 Layout::layout_group
<32, true>(Symbol_table
* symtab
,
3578 Sized_relobj
<32, true>* object
,
3580 const char* group_section_name
,
3581 const char* signature
,
3582 const elfcpp::Shdr
<32, true>& shdr
,
3583 elfcpp::Elf_Word flags
,
3584 std::vector
<unsigned int>* shndxes
);
3587 #ifdef HAVE_TARGET_64_LITTLE
3590 Layout::layout_group
<64, false>(Symbol_table
* symtab
,
3591 Sized_relobj
<64, false>* object
,
3593 const char* group_section_name
,
3594 const char* signature
,
3595 const elfcpp::Shdr
<64, false>& shdr
,
3596 elfcpp::Elf_Word flags
,
3597 std::vector
<unsigned int>* shndxes
);
3600 #ifdef HAVE_TARGET_64_BIG
3603 Layout::layout_group
<64, true>(Symbol_table
* symtab
,
3604 Sized_relobj
<64, true>* object
,
3606 const char* group_section_name
,
3607 const char* signature
,
3608 const elfcpp::Shdr
<64, true>& shdr
,
3609 elfcpp::Elf_Word flags
,
3610 std::vector
<unsigned int>* shndxes
);
3613 #ifdef HAVE_TARGET_32_LITTLE
3616 Layout::layout_eh_frame
<32, false>(Sized_relobj
<32, false>* object
,
3617 const unsigned char* symbols
,
3619 const unsigned char* symbol_names
,
3620 off_t symbol_names_size
,
3622 const elfcpp::Shdr
<32, false>& shdr
,
3623 unsigned int reloc_shndx
,
3624 unsigned int reloc_type
,
3628 #ifdef HAVE_TARGET_32_BIG
3631 Layout::layout_eh_frame
<32, true>(Sized_relobj
<32, true>* object
,
3632 const unsigned char* symbols
,
3634 const unsigned char* symbol_names
,
3635 off_t symbol_names_size
,
3637 const elfcpp::Shdr
<32, true>& shdr
,
3638 unsigned int reloc_shndx
,
3639 unsigned int reloc_type
,
3643 #ifdef HAVE_TARGET_64_LITTLE
3646 Layout::layout_eh_frame
<64, false>(Sized_relobj
<64, false>* object
,
3647 const unsigned char* symbols
,
3649 const unsigned char* symbol_names
,
3650 off_t symbol_names_size
,
3652 const elfcpp::Shdr
<64, false>& shdr
,
3653 unsigned int reloc_shndx
,
3654 unsigned int reloc_type
,
3658 #ifdef HAVE_TARGET_64_BIG
3661 Layout::layout_eh_frame
<64, true>(Sized_relobj
<64, true>* object
,
3662 const unsigned char* symbols
,
3664 const unsigned char* symbol_names
,
3665 off_t symbol_names_size
,
3667 const elfcpp::Shdr
<64, true>& shdr
,
3668 unsigned int reloc_shndx
,
3669 unsigned int reloc_type
,
3673 } // End namespace gold.