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
)
420 (*output_section_slot
)->update_flags_for_input_section(flags
);
421 return *output_section_slot
;
424 // We don't put sections found in the linker script into
425 // SECTION_NAME_MAP_. That keeps us from getting confused
426 // if an orphan section is mapped to a section with the same
427 // name as one in the linker script.
429 name
= this->namepool_
.add(name
, false, NULL
);
431 Output_section
* os
= this->make_output_section(name
, type
, flags
);
432 os
->set_found_in_sections_clause();
433 *output_section_slot
= os
;
438 // FIXME: Handle SHF_OS_NONCONFORMING somewhere.
440 // Turn NAME from the name of the input section into the name of the
443 size_t len
= strlen(name
);
445 && !this->script_options_
->saw_sections_clause()
446 && !parameters
->options().relocatable())
447 name
= Layout::output_section_name(name
, &len
);
449 Stringpool::Key name_key
;
450 name
= this->namepool_
.add_with_length(name
, len
, true, &name_key
);
452 // Find or make the output section. The output section is selected
453 // based on the section name, type, and flags.
454 return this->get_output_section(name
, name_key
, type
, flags
);
457 // Return the output section to use for input section SHNDX, with name
458 // NAME, with header HEADER, from object OBJECT. RELOC_SHNDX is the
459 // index of a relocation section which applies to this section, or 0
460 // if none, or -1U if more than one. RELOC_TYPE is the type of the
461 // relocation section if there is one. Set *OFF to the offset of this
462 // input section without the output section. Return NULL if the
463 // section should be discarded. Set *OFF to -1 if the section
464 // contents should not be written directly to the output file, but
465 // will instead receive special handling.
467 template<int size
, bool big_endian
>
469 Layout::layout(Sized_relobj
<size
, big_endian
>* object
, unsigned int shndx
,
470 const char* name
, const elfcpp::Shdr
<size
, big_endian
>& shdr
,
471 unsigned int reloc_shndx
, unsigned int, off_t
* off
)
475 if (!this->include_section(object
, name
, shdr
))
480 // In a relocatable link a grouped section must not be combined with
481 // any other sections.
482 if (parameters
->options().relocatable()
483 && (shdr
.get_sh_flags() & elfcpp::SHF_GROUP
) != 0)
485 name
= this->namepool_
.add(name
, true, NULL
);
486 os
= this->make_output_section(name
, shdr
.get_sh_type(),
487 shdr
.get_sh_flags());
491 os
= this->choose_output_section(object
, name
, shdr
.get_sh_type(),
492 shdr
.get_sh_flags(), true);
497 // By default the GNU linker sorts input sections whose names match
498 // .ctor.*, .dtor.*, .init_array.*, or .fini_array.*. The sections
499 // are sorted by name. This is used to implement constructor
500 // priority ordering. We are compatible.
501 if (!this->script_options_
->saw_sections_clause()
502 && (is_prefix_of(".ctors.", name
)
503 || is_prefix_of(".dtors.", name
)
504 || is_prefix_of(".init_array.", name
)
505 || is_prefix_of(".fini_array.", name
)))
506 os
->set_must_sort_attached_input_sections();
508 // FIXME: Handle SHF_LINK_ORDER somewhere.
510 *off
= os
->add_input_section(object
, shndx
, name
, shdr
, reloc_shndx
,
511 this->script_options_
->saw_sections_clause());
516 // Handle a relocation section when doing a relocatable link.
518 template<int size
, bool big_endian
>
520 Layout::layout_reloc(Sized_relobj
<size
, big_endian
>* object
,
522 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
523 Output_section
* data_section
,
524 Relocatable_relocs
* rr
)
526 gold_assert(parameters
->options().relocatable()
527 || parameters
->options().emit_relocs());
529 int sh_type
= shdr
.get_sh_type();
532 if (sh_type
== elfcpp::SHT_REL
)
534 else if (sh_type
== elfcpp::SHT_RELA
)
538 name
+= data_section
->name();
540 Output_section
* os
= this->choose_output_section(object
, name
.c_str(),
545 os
->set_should_link_to_symtab();
546 os
->set_info_section(data_section
);
548 Output_section_data
* posd
;
549 if (sh_type
== elfcpp::SHT_REL
)
551 os
->set_entsize(elfcpp::Elf_sizes
<size
>::rel_size
);
552 posd
= new Output_relocatable_relocs
<elfcpp::SHT_REL
,
556 else if (sh_type
== elfcpp::SHT_RELA
)
558 os
->set_entsize(elfcpp::Elf_sizes
<size
>::rela_size
);
559 posd
= new Output_relocatable_relocs
<elfcpp::SHT_RELA
,
566 os
->add_output_section_data(posd
);
567 rr
->set_output_data(posd
);
572 // Handle a group section when doing a relocatable link.
574 template<int size
, bool big_endian
>
576 Layout::layout_group(Symbol_table
* symtab
,
577 Sized_relobj
<size
, big_endian
>* object
,
579 const char* group_section_name
,
580 const char* signature
,
581 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
582 elfcpp::Elf_Word flags
,
583 std::vector
<unsigned int>* shndxes
)
585 gold_assert(parameters
->options().relocatable());
586 gold_assert(shdr
.get_sh_type() == elfcpp::SHT_GROUP
);
587 group_section_name
= this->namepool_
.add(group_section_name
, true, NULL
);
588 Output_section
* os
= this->make_output_section(group_section_name
,
590 shdr
.get_sh_flags());
592 // We need to find a symbol with the signature in the symbol table.
593 // If we don't find one now, we need to look again later.
594 Symbol
* sym
= symtab
->lookup(signature
, NULL
);
596 os
->set_info_symndx(sym
);
599 // Reserve some space to minimize reallocations.
600 if (this->group_signatures_
.empty())
601 this->group_signatures_
.reserve(this->number_of_input_files_
* 16);
603 // We will wind up using a symbol whose name is the signature.
604 // So just put the signature in the symbol name pool to save it.
605 signature
= symtab
->canonicalize_name(signature
);
606 this->group_signatures_
.push_back(Group_signature(os
, signature
));
609 os
->set_should_link_to_symtab();
612 section_size_type entry_count
=
613 convert_to_section_size_type(shdr
.get_sh_size() / 4);
614 Output_section_data
* posd
=
615 new Output_data_group
<size
, big_endian
>(object
, entry_count
, flags
,
617 os
->add_output_section_data(posd
);
620 // Special GNU handling of sections name .eh_frame. They will
621 // normally hold exception frame data as defined by the C++ ABI
622 // (http://codesourcery.com/cxx-abi/).
624 template<int size
, bool big_endian
>
626 Layout::layout_eh_frame(Sized_relobj
<size
, big_endian
>* object
,
627 const unsigned char* symbols
,
629 const unsigned char* symbol_names
,
630 off_t symbol_names_size
,
632 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
633 unsigned int reloc_shndx
, unsigned int reloc_type
,
636 gold_assert(shdr
.get_sh_type() == elfcpp::SHT_PROGBITS
);
637 gold_assert((shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) != 0);
639 const char* const name
= ".eh_frame";
640 Output_section
* os
= this->choose_output_section(object
,
642 elfcpp::SHT_PROGBITS
,
648 if (this->eh_frame_section_
== NULL
)
650 this->eh_frame_section_
= os
;
651 this->eh_frame_data_
= new Eh_frame();
653 if (parameters
->options().eh_frame_hdr())
655 Output_section
* hdr_os
=
656 this->choose_output_section(NULL
,
658 elfcpp::SHT_PROGBITS
,
664 Eh_frame_hdr
* hdr_posd
= new Eh_frame_hdr(os
,
665 this->eh_frame_data_
);
666 hdr_os
->add_output_section_data(hdr_posd
);
668 hdr_os
->set_after_input_sections();
670 if (!this->script_options_
->saw_phdrs_clause())
672 Output_segment
* hdr_oseg
;
673 hdr_oseg
= this->make_output_segment(elfcpp::PT_GNU_EH_FRAME
,
675 hdr_oseg
->add_output_section(hdr_os
, elfcpp::PF_R
);
678 this->eh_frame_data_
->set_eh_frame_hdr(hdr_posd
);
683 gold_assert(this->eh_frame_section_
== os
);
685 if (this->eh_frame_data_
->add_ehframe_input_section(object
,
694 os
->update_flags_for_input_section(shdr
.get_sh_flags());
696 // We found a .eh_frame section we are going to optimize, so now
697 // we can add the set of optimized sections to the output
698 // section. We need to postpone adding this until we've found a
699 // section we can optimize so that the .eh_frame section in
700 // crtbegin.o winds up at the start of the output section.
701 if (!this->added_eh_frame_data_
)
703 os
->add_output_section_data(this->eh_frame_data_
);
704 this->added_eh_frame_data_
= true;
710 // We couldn't handle this .eh_frame section for some reason.
711 // Add it as a normal section.
712 bool saw_sections_clause
= this->script_options_
->saw_sections_clause();
713 *off
= os
->add_input_section(object
, shndx
, name
, shdr
, reloc_shndx
,
714 saw_sections_clause
);
720 // Add POSD to an output section using NAME, TYPE, and FLAGS. Return
721 // the output section.
724 Layout::add_output_section_data(const char* name
, elfcpp::Elf_Word type
,
725 elfcpp::Elf_Xword flags
,
726 Output_section_data
* posd
)
728 Output_section
* os
= this->choose_output_section(NULL
, name
, type
, flags
,
731 os
->add_output_section_data(posd
);
735 // Map section flags to segment flags.
738 Layout::section_flags_to_segment(elfcpp::Elf_Xword flags
)
740 elfcpp::Elf_Word ret
= elfcpp::PF_R
;
741 if ((flags
& elfcpp::SHF_WRITE
) != 0)
743 if ((flags
& elfcpp::SHF_EXECINSTR
) != 0)
748 // Sometimes we compress sections. This is typically done for
749 // sections that are not part of normal program execution (such as
750 // .debug_* sections), and where the readers of these sections know
751 // how to deal with compressed sections. (To make it easier for them,
752 // we will rename the ouput section in such cases from .foo to
753 // .foo.zlib.nnnn, where nnnn is the uncompressed size.) This routine
754 // doesn't say for certain whether we'll compress -- it depends on
755 // commandline options as well -- just whether this section is a
756 // candidate for compression.
759 is_compressible_debug_section(const char* secname
)
761 return (strncmp(secname
, ".debug", sizeof(".debug") - 1) == 0);
764 // Make a new Output_section, and attach it to segments as
768 Layout::make_output_section(const char* name
, elfcpp::Elf_Word type
,
769 elfcpp::Elf_Xword flags
)
772 if ((flags
& elfcpp::SHF_ALLOC
) == 0
773 && strcmp(parameters
->options().compress_debug_sections(), "none") != 0
774 && is_compressible_debug_section(name
))
775 os
= new Output_compressed_section(¶meters
->options(), name
, type
,
778 else if ((flags
& elfcpp::SHF_ALLOC
) == 0
779 && parameters
->options().strip_debug_non_line()
780 && strcmp(".debug_abbrev", name
) == 0)
782 os
= this->debug_abbrev_
= new Output_reduced_debug_abbrev_section(
784 if (this->debug_info_
)
785 this->debug_info_
->set_abbreviations(this->debug_abbrev_
);
787 else if ((flags
& elfcpp::SHF_ALLOC
) == 0
788 && parameters
->options().strip_debug_non_line()
789 && strcmp(".debug_info", name
) == 0)
791 os
= this->debug_info_
= new Output_reduced_debug_info_section(
793 if (this->debug_abbrev_
)
794 this->debug_info_
->set_abbreviations(this->debug_abbrev_
);
797 os
= new Output_section(name
, type
, flags
);
799 parameters
->target().new_output_section(os
);
801 this->section_list_
.push_back(os
);
803 // The GNU linker by default sorts some sections by priority, so we
804 // do the same. We need to know that this might happen before we
805 // attach any input sections.
806 if (!this->script_options_
->saw_sections_clause()
807 && (strcmp(name
, ".ctors") == 0
808 || strcmp(name
, ".dtors") == 0
809 || strcmp(name
, ".init_array") == 0
810 || strcmp(name
, ".fini_array") == 0))
811 os
->set_may_sort_attached_input_sections();
813 // With -z relro, we have to recognize the special sections by name.
814 // There is no other way.
815 if (!this->script_options_
->saw_sections_clause()
816 && parameters
->options().relro()
817 && type
== elfcpp::SHT_PROGBITS
818 && (flags
& elfcpp::SHF_ALLOC
) != 0
819 && (flags
& elfcpp::SHF_WRITE
) != 0)
821 if (strcmp(name
, ".data.rel.ro") == 0)
823 else if (strcmp(name
, ".data.rel.ro.local") == 0)
826 os
->set_is_relro_local();
830 // Check for .stab*str sections, as .stab* sections need to link to
832 if (type
== elfcpp::SHT_STRTAB
833 && !this->have_stabstr_section_
834 && strncmp(name
, ".stab", 5) == 0
835 && strcmp(name
+ strlen(name
) - 3, "str") == 0)
836 this->have_stabstr_section_
= true;
838 // If we have already attached the sections to segments, then we
839 // need to attach this one now. This happens for sections created
840 // directly by the linker.
841 if (this->sections_are_attached_
)
842 this->attach_section_to_segment(os
);
847 // Attach output sections to segments. This is called after we have
848 // seen all the input sections.
851 Layout::attach_sections_to_segments()
853 for (Section_list::iterator p
= this->section_list_
.begin();
854 p
!= this->section_list_
.end();
856 this->attach_section_to_segment(*p
);
858 this->sections_are_attached_
= true;
861 // Attach an output section to a segment.
864 Layout::attach_section_to_segment(Output_section
* os
)
866 if ((os
->flags() & elfcpp::SHF_ALLOC
) == 0)
867 this->unattached_section_list_
.push_back(os
);
869 this->attach_allocated_section_to_segment(os
);
872 // Attach an allocated output section to a segment.
875 Layout::attach_allocated_section_to_segment(Output_section
* os
)
877 elfcpp::Elf_Xword flags
= os
->flags();
878 gold_assert((flags
& elfcpp::SHF_ALLOC
) != 0);
880 if (parameters
->options().relocatable())
883 // If we have a SECTIONS clause, we can't handle the attachment to
884 // segments until after we've seen all the sections.
885 if (this->script_options_
->saw_sections_clause())
888 gold_assert(!this->script_options_
->saw_phdrs_clause());
890 // This output section goes into a PT_LOAD segment.
892 elfcpp::Elf_Word seg_flags
= Layout::section_flags_to_segment(flags
);
894 // In general the only thing we really care about for PT_LOAD
895 // segments is whether or not they are writable, so that is how we
896 // search for them. Large data sections also go into their own
897 // PT_LOAD segment. People who need segments sorted on some other
898 // basis will have to use a linker script.
900 Segment_list::const_iterator p
;
901 for (p
= this->segment_list_
.begin();
902 p
!= this->segment_list_
.end();
905 if ((*p
)->type() != elfcpp::PT_LOAD
)
907 if (!parameters
->options().omagic()
908 && ((*p
)->flags() & elfcpp::PF_W
) != (seg_flags
& elfcpp::PF_W
))
910 // If -Tbss was specified, we need to separate the data and BSS
912 if (parameters
->options().user_set_Tbss())
914 if ((os
->type() == elfcpp::SHT_NOBITS
)
915 == (*p
)->has_any_data_sections())
918 if (os
->is_large_data_section() && !(*p
)->is_large_data_segment())
921 (*p
)->add_output_section(os
, seg_flags
);
925 if (p
== this->segment_list_
.end())
927 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_LOAD
,
929 if (os
->is_large_data_section())
930 oseg
->set_is_large_data_segment();
931 oseg
->add_output_section(os
, seg_flags
);
934 // If we see a loadable SHT_NOTE section, we create a PT_NOTE
936 if (os
->type() == elfcpp::SHT_NOTE
)
938 // See if we already have an equivalent PT_NOTE segment.
939 for (p
= this->segment_list_
.begin();
940 p
!= segment_list_
.end();
943 if ((*p
)->type() == elfcpp::PT_NOTE
944 && (((*p
)->flags() & elfcpp::PF_W
)
945 == (seg_flags
& elfcpp::PF_W
)))
947 (*p
)->add_output_section(os
, seg_flags
);
952 if (p
== this->segment_list_
.end())
954 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_NOTE
,
956 oseg
->add_output_section(os
, seg_flags
);
960 // If we see a loadable SHF_TLS section, we create a PT_TLS
961 // segment. There can only be one such segment.
962 if ((flags
& elfcpp::SHF_TLS
) != 0)
964 if (this->tls_segment_
== NULL
)
965 this->make_output_segment(elfcpp::PT_TLS
, seg_flags
);
966 this->tls_segment_
->add_output_section(os
, seg_flags
);
969 // If -z relro is in effect, and we see a relro section, we create a
970 // PT_GNU_RELRO segment. There can only be one such segment.
971 if (os
->is_relro() && parameters
->options().relro())
973 gold_assert(seg_flags
== (elfcpp::PF_R
| elfcpp::PF_W
));
974 if (this->relro_segment_
== NULL
)
975 this->make_output_segment(elfcpp::PT_GNU_RELRO
, seg_flags
);
976 this->relro_segment_
->add_output_section(os
, seg_flags
);
980 // Make an output section for a script.
983 Layout::make_output_section_for_script(const char* name
)
985 name
= this->namepool_
.add(name
, false, NULL
);
986 Output_section
* os
= this->make_output_section(name
, elfcpp::SHT_PROGBITS
,
988 os
->set_found_in_sections_clause();
992 // Return the number of segments we expect to see.
995 Layout::expected_segment_count() const
997 size_t ret
= this->segment_list_
.size();
999 // If we didn't see a SECTIONS clause in a linker script, we should
1000 // already have the complete list of segments. Otherwise we ask the
1001 // SECTIONS clause how many segments it expects, and add in the ones
1002 // we already have (PT_GNU_STACK, PT_GNU_EH_FRAME, etc.)
1004 if (!this->script_options_
->saw_sections_clause())
1008 const Script_sections
* ss
= this->script_options_
->script_sections();
1009 return ret
+ ss
->expected_segment_count(this);
1013 // Handle the .note.GNU-stack section at layout time. SEEN_GNU_STACK
1014 // is whether we saw a .note.GNU-stack section in the object file.
1015 // GNU_STACK_FLAGS is the section flags. The flags give the
1016 // protection required for stack memory. We record this in an
1017 // executable as a PT_GNU_STACK segment. If an object file does not
1018 // have a .note.GNU-stack segment, we must assume that it is an old
1019 // object. On some targets that will force an executable stack.
1022 Layout::layout_gnu_stack(bool seen_gnu_stack
, uint64_t gnu_stack_flags
)
1024 if (!seen_gnu_stack
)
1025 this->input_without_gnu_stack_note_
= true;
1028 this->input_with_gnu_stack_note_
= true;
1029 if ((gnu_stack_flags
& elfcpp::SHF_EXECINSTR
) != 0)
1030 this->input_requires_executable_stack_
= true;
1034 // Create automatic note sections.
1037 Layout::create_notes()
1039 this->create_gold_note();
1040 this->create_executable_stack_info();
1041 this->create_build_id();
1044 // Create the dynamic sections which are needed before we read the
1048 Layout::create_initial_dynamic_sections(Symbol_table
* symtab
)
1050 if (parameters
->doing_static_link())
1053 this->dynamic_section_
= this->choose_output_section(NULL
, ".dynamic",
1054 elfcpp::SHT_DYNAMIC
,
1056 | elfcpp::SHF_WRITE
),
1058 this->dynamic_section_
->set_is_relro();
1060 symtab
->define_in_output_data("_DYNAMIC", NULL
, this->dynamic_section_
, 0, 0,
1061 elfcpp::STT_OBJECT
, elfcpp::STB_LOCAL
,
1062 elfcpp::STV_HIDDEN
, 0, false, false);
1064 this->dynamic_data_
= new Output_data_dynamic(&this->dynpool_
);
1066 this->dynamic_section_
->add_output_section_data(this->dynamic_data_
);
1069 // For each output section whose name can be represented as C symbol,
1070 // define __start and __stop symbols for the section. This is a GNU
1074 Layout::define_section_symbols(Symbol_table
* symtab
)
1076 for (Section_list::const_iterator p
= this->section_list_
.begin();
1077 p
!= this->section_list_
.end();
1080 const char* const name
= (*p
)->name();
1081 if (name
[strspn(name
,
1083 "ABCDEFGHIJKLMNOPWRSTUVWXYZ"
1084 "abcdefghijklmnopqrstuvwxyz"
1088 const std::string
name_string(name
);
1089 const std::string
start_name("__start_" + name_string
);
1090 const std::string
stop_name("__stop_" + name_string
);
1092 symtab
->define_in_output_data(start_name
.c_str(),
1099 elfcpp::STV_DEFAULT
,
1101 false, // offset_is_from_end
1102 true); // only_if_ref
1104 symtab
->define_in_output_data(stop_name
.c_str(),
1111 elfcpp::STV_DEFAULT
,
1113 true, // offset_is_from_end
1114 true); // only_if_ref
1119 // Define symbols for group signatures.
1122 Layout::define_group_signatures(Symbol_table
* symtab
)
1124 for (Group_signatures::iterator p
= this->group_signatures_
.begin();
1125 p
!= this->group_signatures_
.end();
1128 Symbol
* sym
= symtab
->lookup(p
->signature
, NULL
);
1130 p
->section
->set_info_symndx(sym
);
1133 // Force the name of the group section to the group
1134 // signature, and use the group's section symbol as the
1135 // signature symbol.
1136 if (strcmp(p
->section
->name(), p
->signature
) != 0)
1138 const char* name
= this->namepool_
.add(p
->signature
,
1140 p
->section
->set_name(name
);
1142 p
->section
->set_needs_symtab_index();
1143 p
->section
->set_info_section_symndx(p
->section
);
1147 this->group_signatures_
.clear();
1150 // Find the first read-only PT_LOAD segment, creating one if
1154 Layout::find_first_load_seg()
1156 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
1157 p
!= this->segment_list_
.end();
1160 if ((*p
)->type() == elfcpp::PT_LOAD
1161 && ((*p
)->flags() & elfcpp::PF_R
) != 0
1162 && (parameters
->options().omagic()
1163 || ((*p
)->flags() & elfcpp::PF_W
) == 0))
1167 gold_assert(!this->script_options_
->saw_phdrs_clause());
1169 Output_segment
* load_seg
= this->make_output_segment(elfcpp::PT_LOAD
,
1174 // Finalize the layout. When this is called, we have created all the
1175 // output sections and all the output segments which are based on
1176 // input sections. We have several things to do, and we have to do
1177 // them in the right order, so that we get the right results correctly
1180 // 1) Finalize the list of output segments and create the segment
1183 // 2) Finalize the dynamic symbol table and associated sections.
1185 // 3) Determine the final file offset of all the output segments.
1187 // 4) Determine the final file offset of all the SHF_ALLOC output
1190 // 5) Create the symbol table sections and the section name table
1193 // 6) Finalize the symbol table: set symbol values to their final
1194 // value and make a final determination of which symbols are going
1195 // into the output symbol table.
1197 // 7) Create the section table header.
1199 // 8) Determine the final file offset of all the output sections which
1200 // are not SHF_ALLOC, including the section table header.
1202 // 9) Finalize the ELF file header.
1204 // This function returns the size of the output file.
1207 Layout::finalize(const Input_objects
* input_objects
, Symbol_table
* symtab
,
1208 Target
* target
, const Task
* task
)
1210 target
->finalize_sections(this);
1212 this->count_local_symbols(task
, input_objects
);
1214 this->link_stabs_sections();
1216 Output_segment
* phdr_seg
= NULL
;
1217 if (!parameters
->options().relocatable() && !parameters
->doing_static_link())
1219 // There was a dynamic object in the link. We need to create
1220 // some information for the dynamic linker.
1222 // Create the PT_PHDR segment which will hold the program
1224 if (!this->script_options_
->saw_phdrs_clause())
1225 phdr_seg
= this->make_output_segment(elfcpp::PT_PHDR
, elfcpp::PF_R
);
1227 // Create the dynamic symbol table, including the hash table.
1228 Output_section
* dynstr
;
1229 std::vector
<Symbol
*> dynamic_symbols
;
1230 unsigned int local_dynamic_count
;
1231 Versions
versions(*this->script_options()->version_script_info(),
1233 this->create_dynamic_symtab(input_objects
, symtab
, &dynstr
,
1234 &local_dynamic_count
, &dynamic_symbols
,
1237 // Create the .interp section to hold the name of the
1238 // interpreter, and put it in a PT_INTERP segment.
1239 if (!parameters
->options().shared())
1240 this->create_interp(target
);
1242 // Finish the .dynamic section to hold the dynamic data, and put
1243 // it in a PT_DYNAMIC segment.
1244 this->finish_dynamic_section(input_objects
, symtab
);
1246 // We should have added everything we need to the dynamic string
1248 this->dynpool_
.set_string_offsets();
1250 // Create the version sections. We can't do this until the
1251 // dynamic string table is complete.
1252 this->create_version_sections(&versions
, symtab
, local_dynamic_count
,
1253 dynamic_symbols
, dynstr
);
1256 if (this->incremental_inputs_
)
1258 this->incremental_inputs_
->finalize();
1259 this->create_incremental_info_sections();
1262 // If there is a SECTIONS clause, put all the input sections into
1263 // the required order.
1264 Output_segment
* load_seg
;
1265 if (this->script_options_
->saw_sections_clause())
1266 load_seg
= this->set_section_addresses_from_script(symtab
);
1267 else if (parameters
->options().relocatable())
1270 load_seg
= this->find_first_load_seg();
1272 if (parameters
->options().oformat_enum()
1273 != General_options::OBJECT_FORMAT_ELF
)
1276 gold_assert(phdr_seg
== NULL
|| load_seg
!= NULL
);
1278 // Lay out the segment headers.
1279 Output_segment_headers
* segment_headers
;
1280 if (parameters
->options().relocatable())
1281 segment_headers
= NULL
;
1284 segment_headers
= new Output_segment_headers(this->segment_list_
);
1285 if (load_seg
!= NULL
)
1286 load_seg
->add_initial_output_data(segment_headers
);
1287 if (phdr_seg
!= NULL
)
1288 phdr_seg
->add_initial_output_data(segment_headers
);
1291 // Lay out the file header.
1292 Output_file_header
* file_header
;
1293 file_header
= new Output_file_header(target
, symtab
, segment_headers
,
1294 parameters
->options().entry());
1295 if (load_seg
!= NULL
)
1296 load_seg
->add_initial_output_data(file_header
);
1298 this->special_output_list_
.push_back(file_header
);
1299 if (segment_headers
!= NULL
)
1300 this->special_output_list_
.push_back(segment_headers
);
1302 if (this->script_options_
->saw_phdrs_clause()
1303 && !parameters
->options().relocatable())
1305 // Support use of FILEHDRS and PHDRS attachments in a PHDRS
1306 // clause in a linker script.
1307 Script_sections
* ss
= this->script_options_
->script_sections();
1308 ss
->put_headers_in_phdrs(file_header
, segment_headers
);
1311 // We set the output section indexes in set_segment_offsets and
1312 // set_section_indexes.
1313 unsigned int shndx
= 1;
1315 // Set the file offsets of all the segments, and all the sections
1318 if (!parameters
->options().relocatable())
1319 off
= this->set_segment_offsets(target
, load_seg
, &shndx
);
1321 off
= this->set_relocatable_section_offsets(file_header
, &shndx
);
1323 // Set the file offsets of all the non-data sections we've seen so
1324 // far which don't have to wait for the input sections. We need
1325 // this in order to finalize local symbols in non-allocated
1327 off
= this->set_section_offsets(off
, BEFORE_INPUT_SECTIONS_PASS
);
1329 // Set the section indexes of all unallocated sections seen so far,
1330 // in case any of them are somehow referenced by a symbol.
1331 shndx
= this->set_section_indexes(shndx
);
1333 // Create the symbol table sections.
1334 this->create_symtab_sections(input_objects
, symtab
, shndx
, &off
);
1335 if (!parameters
->doing_static_link())
1336 this->assign_local_dynsym_offsets(input_objects
);
1338 // Process any symbol assignments from a linker script. This must
1339 // be called after the symbol table has been finalized.
1340 this->script_options_
->finalize_symbols(symtab
, this);
1342 // Create the .shstrtab section.
1343 Output_section
* shstrtab_section
= this->create_shstrtab();
1345 // Set the file offsets of the rest of the non-data sections which
1346 // don't have to wait for the input sections.
1347 off
= this->set_section_offsets(off
, BEFORE_INPUT_SECTIONS_PASS
);
1349 // Now that all sections have been created, set the section indexes
1350 // for any sections which haven't been done yet.
1351 shndx
= this->set_section_indexes(shndx
);
1353 // Create the section table header.
1354 this->create_shdrs(shstrtab_section
, &off
);
1356 // If there are no sections which require postprocessing, we can
1357 // handle the section names now, and avoid a resize later.
1358 if (!this->any_postprocessing_sections_
)
1359 off
= this->set_section_offsets(off
,
1360 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
);
1362 file_header
->set_section_info(this->section_headers_
, shstrtab_section
);
1364 // Now we know exactly where everything goes in the output file
1365 // (except for non-allocated sections which require postprocessing).
1366 Output_data::layout_complete();
1368 this->output_file_size_
= off
;
1373 // Create a note header following the format defined in the ELF ABI.
1374 // NAME is the name, NOTE_TYPE is the type, SECTION_NAME is the name
1375 // of the section to create, DESCSZ is the size of the descriptor.
1376 // ALLOCATE is true if the section should be allocated in memory.
1377 // This returns the new note section. It sets *TRAILING_PADDING to
1378 // the number of trailing zero bytes required.
1381 Layout::create_note(const char* name
, int note_type
,
1382 const char* section_name
, size_t descsz
,
1383 bool allocate
, size_t* trailing_padding
)
1385 // Authorities all agree that the values in a .note field should
1386 // be aligned on 4-byte boundaries for 32-bit binaries. However,
1387 // they differ on what the alignment is for 64-bit binaries.
1388 // The GABI says unambiguously they take 8-byte alignment:
1389 // http://sco.com/developers/gabi/latest/ch5.pheader.html#note_section
1390 // Other documentation says alignment should always be 4 bytes:
1391 // http://www.netbsd.org/docs/kernel/elf-notes.html#note-format
1392 // GNU ld and GNU readelf both support the latter (at least as of
1393 // version 2.16.91), and glibc always generates the latter for
1394 // .note.ABI-tag (as of version 1.6), so that's the one we go with
1396 #ifdef GABI_FORMAT_FOR_DOTNOTE_SECTION // This is not defined by default.
1397 const int size
= parameters
->target().get_size();
1399 const int size
= 32;
1402 // The contents of the .note section.
1403 size_t namesz
= strlen(name
) + 1;
1404 size_t aligned_namesz
= align_address(namesz
, size
/ 8);
1405 size_t aligned_descsz
= align_address(descsz
, size
/ 8);
1407 size_t notehdrsz
= 3 * (size
/ 8) + aligned_namesz
;
1409 unsigned char* buffer
= new unsigned char[notehdrsz
];
1410 memset(buffer
, 0, notehdrsz
);
1412 bool is_big_endian
= parameters
->target().is_big_endian();
1418 elfcpp::Swap
<32, false>::writeval(buffer
, namesz
);
1419 elfcpp::Swap
<32, false>::writeval(buffer
+ 4, descsz
);
1420 elfcpp::Swap
<32, false>::writeval(buffer
+ 8, note_type
);
1424 elfcpp::Swap
<32, true>::writeval(buffer
, namesz
);
1425 elfcpp::Swap
<32, true>::writeval(buffer
+ 4, descsz
);
1426 elfcpp::Swap
<32, true>::writeval(buffer
+ 8, note_type
);
1429 else if (size
== 64)
1433 elfcpp::Swap
<64, false>::writeval(buffer
, namesz
);
1434 elfcpp::Swap
<64, false>::writeval(buffer
+ 8, descsz
);
1435 elfcpp::Swap
<64, false>::writeval(buffer
+ 16, note_type
);
1439 elfcpp::Swap
<64, true>::writeval(buffer
, namesz
);
1440 elfcpp::Swap
<64, true>::writeval(buffer
+ 8, descsz
);
1441 elfcpp::Swap
<64, true>::writeval(buffer
+ 16, note_type
);
1447 memcpy(buffer
+ 3 * (size
/ 8), name
, namesz
);
1449 elfcpp::Elf_Xword flags
= 0;
1451 flags
= elfcpp::SHF_ALLOC
;
1452 Output_section
* os
= this->choose_output_section(NULL
, section_name
,
1458 Output_section_data
* posd
= new Output_data_const_buffer(buffer
, notehdrsz
,
1461 os
->add_output_section_data(posd
);
1463 *trailing_padding
= aligned_descsz
- descsz
;
1468 // For an executable or shared library, create a note to record the
1469 // version of gold used to create the binary.
1472 Layout::create_gold_note()
1474 if (parameters
->options().relocatable())
1477 std::string desc
= std::string("gold ") + gold::get_version_string();
1479 size_t trailing_padding
;
1480 Output_section
*os
= this->create_note("GNU", elfcpp::NT_GNU_GOLD_VERSION
,
1481 ".note.gnu.gold-version", desc
.size(),
1482 false, &trailing_padding
);
1486 Output_section_data
* posd
= new Output_data_const(desc
, 4);
1487 os
->add_output_section_data(posd
);
1489 if (trailing_padding
> 0)
1491 posd
= new Output_data_zero_fill(trailing_padding
, 0);
1492 os
->add_output_section_data(posd
);
1496 // Record whether the stack should be executable. This can be set
1497 // from the command line using the -z execstack or -z noexecstack
1498 // options. Otherwise, if any input file has a .note.GNU-stack
1499 // section with the SHF_EXECINSTR flag set, the stack should be
1500 // executable. Otherwise, if at least one input file a
1501 // .note.GNU-stack section, and some input file has no .note.GNU-stack
1502 // section, we use the target default for whether the stack should be
1503 // executable. Otherwise, we don't generate a stack note. When
1504 // generating a object file, we create a .note.GNU-stack section with
1505 // the appropriate marking. When generating an executable or shared
1506 // library, we create a PT_GNU_STACK segment.
1509 Layout::create_executable_stack_info()
1511 bool is_stack_executable
;
1512 if (parameters
->options().is_execstack_set())
1513 is_stack_executable
= parameters
->options().is_stack_executable();
1514 else if (!this->input_with_gnu_stack_note_
)
1518 if (this->input_requires_executable_stack_
)
1519 is_stack_executable
= true;
1520 else if (this->input_without_gnu_stack_note_
)
1521 is_stack_executable
=
1522 parameters
->target().is_default_stack_executable();
1524 is_stack_executable
= false;
1527 if (parameters
->options().relocatable())
1529 const char* name
= this->namepool_
.add(".note.GNU-stack", false, NULL
);
1530 elfcpp::Elf_Xword flags
= 0;
1531 if (is_stack_executable
)
1532 flags
|= elfcpp::SHF_EXECINSTR
;
1533 this->make_output_section(name
, elfcpp::SHT_PROGBITS
, flags
);
1537 if (this->script_options_
->saw_phdrs_clause())
1539 int flags
= elfcpp::PF_R
| elfcpp::PF_W
;
1540 if (is_stack_executable
)
1541 flags
|= elfcpp::PF_X
;
1542 this->make_output_segment(elfcpp::PT_GNU_STACK
, flags
);
1546 // If --build-id was used, set up the build ID note.
1549 Layout::create_build_id()
1551 if (!parameters
->options().user_set_build_id())
1554 const char* style
= parameters
->options().build_id();
1555 if (strcmp(style
, "none") == 0)
1558 // Set DESCSZ to the size of the note descriptor. When possible,
1559 // set DESC to the note descriptor contents.
1562 if (strcmp(style
, "md5") == 0)
1564 else if (strcmp(style
, "sha1") == 0)
1566 else if (strcmp(style
, "uuid") == 0)
1568 const size_t uuidsz
= 128 / 8;
1570 char buffer
[uuidsz
];
1571 memset(buffer
, 0, uuidsz
);
1573 int descriptor
= open_descriptor(-1, "/dev/urandom", O_RDONLY
);
1575 gold_error(_("--build-id=uuid failed: could not open /dev/urandom: %s"),
1579 ssize_t got
= ::read(descriptor
, buffer
, uuidsz
);
1580 release_descriptor(descriptor
, true);
1582 gold_error(_("/dev/urandom: read failed: %s"), strerror(errno
));
1583 else if (static_cast<size_t>(got
) != uuidsz
)
1584 gold_error(_("/dev/urandom: expected %zu bytes, got %zd bytes"),
1588 desc
.assign(buffer
, uuidsz
);
1591 else if (strncmp(style
, "0x", 2) == 0)
1594 const char* p
= style
+ 2;
1597 if (hex_p(p
[0]) && hex_p(p
[1]))
1599 char c
= (hex_value(p
[0]) << 4) | hex_value(p
[1]);
1603 else if (*p
== '-' || *p
== ':')
1606 gold_fatal(_("--build-id argument '%s' not a valid hex number"),
1609 descsz
= desc
.size();
1612 gold_fatal(_("unrecognized --build-id argument '%s'"), style
);
1615 size_t trailing_padding
;
1616 Output_section
* os
= this->create_note("GNU", elfcpp::NT_GNU_BUILD_ID
,
1617 ".note.gnu.build-id", descsz
, true,
1624 // We know the value already, so we fill it in now.
1625 gold_assert(desc
.size() == descsz
);
1627 Output_section_data
* posd
= new Output_data_const(desc
, 4);
1628 os
->add_output_section_data(posd
);
1630 if (trailing_padding
!= 0)
1632 posd
= new Output_data_zero_fill(trailing_padding
, 0);
1633 os
->add_output_section_data(posd
);
1638 // We need to compute a checksum after we have completed the
1640 gold_assert(trailing_padding
== 0);
1641 this->build_id_note_
= new Output_data_zero_fill(descsz
, 4);
1642 os
->add_output_section_data(this->build_id_note_
);
1646 // If we have both .stabXX and .stabXXstr sections, then the sh_link
1647 // field of the former should point to the latter. I'm not sure who
1648 // started this, but the GNU linker does it, and some tools depend
1652 Layout::link_stabs_sections()
1654 if (!this->have_stabstr_section_
)
1657 for (Section_list::iterator p
= this->section_list_
.begin();
1658 p
!= this->section_list_
.end();
1661 if ((*p
)->type() != elfcpp::SHT_STRTAB
)
1664 const char* name
= (*p
)->name();
1665 if (strncmp(name
, ".stab", 5) != 0)
1668 size_t len
= strlen(name
);
1669 if (strcmp(name
+ len
- 3, "str") != 0)
1672 std::string
stab_name(name
, len
- 3);
1673 Output_section
* stab_sec
;
1674 stab_sec
= this->find_output_section(stab_name
.c_str());
1675 if (stab_sec
!= NULL
)
1676 stab_sec
->set_link_section(*p
);
1680 // Create .gnu_incremental_inputs and .gnu_incremental_strtab sections needed
1681 // for the next run of incremental linking to check what has changed.
1684 Layout::create_incremental_info_sections()
1686 gold_assert(this->incremental_inputs_
!= NULL
);
1688 // Add the .gnu_incremental_inputs section.
1689 const char *incremental_inputs_name
=
1690 this->namepool_
.add(".gnu_incremental_inputs", false, NULL
);
1691 Output_section
* inputs_os
=
1692 this->make_output_section(incremental_inputs_name
,
1693 elfcpp::SHT_GNU_INCREMENTAL_INPUTS
, 0);
1694 Output_section_data
* posd
=
1695 this->incremental_inputs_
->create_incremental_inputs_section_data();
1696 inputs_os
->add_output_section_data(posd
);
1698 // Add the .gnu_incremental_strtab section.
1699 const char *incremental_strtab_name
=
1700 this->namepool_
.add(".gnu_incremental_strtab", false, NULL
);
1701 Output_section
* strtab_os
= this->make_output_section(incremental_strtab_name
,
1704 Output_data_strtab
* strtab_data
=
1705 new Output_data_strtab(this->incremental_inputs_
->get_stringpool());
1706 strtab_os
->add_output_section_data(strtab_data
);
1708 inputs_os
->set_link_section(strtab_data
);
1711 // Return whether SEG1 should be before SEG2 in the output file. This
1712 // is based entirely on the segment type and flags. When this is
1713 // called the segment addresses has normally not yet been set.
1716 Layout::segment_precedes(const Output_segment
* seg1
,
1717 const Output_segment
* seg2
)
1719 elfcpp::Elf_Word type1
= seg1
->type();
1720 elfcpp::Elf_Word type2
= seg2
->type();
1722 // The single PT_PHDR segment is required to precede any loadable
1723 // segment. We simply make it always first.
1724 if (type1
== elfcpp::PT_PHDR
)
1726 gold_assert(type2
!= elfcpp::PT_PHDR
);
1729 if (type2
== elfcpp::PT_PHDR
)
1732 // The single PT_INTERP segment is required to precede any loadable
1733 // segment. We simply make it always second.
1734 if (type1
== elfcpp::PT_INTERP
)
1736 gold_assert(type2
!= elfcpp::PT_INTERP
);
1739 if (type2
== elfcpp::PT_INTERP
)
1742 // We then put PT_LOAD segments before any other segments.
1743 if (type1
== elfcpp::PT_LOAD
&& type2
!= elfcpp::PT_LOAD
)
1745 if (type2
== elfcpp::PT_LOAD
&& type1
!= elfcpp::PT_LOAD
)
1748 // We put the PT_TLS segment last except for the PT_GNU_RELRO
1749 // segment, because that is where the dynamic linker expects to find
1750 // it (this is just for efficiency; other positions would also work
1752 if (type1
== elfcpp::PT_TLS
1753 && type2
!= elfcpp::PT_TLS
1754 && type2
!= elfcpp::PT_GNU_RELRO
)
1756 if (type2
== elfcpp::PT_TLS
1757 && type1
!= elfcpp::PT_TLS
1758 && type1
!= elfcpp::PT_GNU_RELRO
)
1761 // We put the PT_GNU_RELRO segment last, because that is where the
1762 // dynamic linker expects to find it (as with PT_TLS, this is just
1764 if (type1
== elfcpp::PT_GNU_RELRO
&& type2
!= elfcpp::PT_GNU_RELRO
)
1766 if (type2
== elfcpp::PT_GNU_RELRO
&& type1
!= elfcpp::PT_GNU_RELRO
)
1769 const elfcpp::Elf_Word flags1
= seg1
->flags();
1770 const elfcpp::Elf_Word flags2
= seg2
->flags();
1772 // The order of non-PT_LOAD segments is unimportant. We simply sort
1773 // by the numeric segment type and flags values. There should not
1774 // be more than one segment with the same type and flags.
1775 if (type1
!= elfcpp::PT_LOAD
)
1778 return type1
< type2
;
1779 gold_assert(flags1
!= flags2
);
1780 return flags1
< flags2
;
1783 // If the addresses are set already, sort by load address.
1784 if (seg1
->are_addresses_set())
1786 if (!seg2
->are_addresses_set())
1789 unsigned int section_count1
= seg1
->output_section_count();
1790 unsigned int section_count2
= seg2
->output_section_count();
1791 if (section_count1
== 0 && section_count2
> 0)
1793 if (section_count1
> 0 && section_count2
== 0)
1796 uint64_t paddr1
= seg1
->first_section_load_address();
1797 uint64_t paddr2
= seg2
->first_section_load_address();
1798 if (paddr1
!= paddr2
)
1799 return paddr1
< paddr2
;
1801 else if (seg2
->are_addresses_set())
1804 // A segment which holds large data comes after a segment which does
1805 // not hold large data.
1806 if (seg1
->is_large_data_segment())
1808 if (!seg2
->is_large_data_segment())
1811 else if (seg2
->is_large_data_segment())
1814 // Otherwise, we sort PT_LOAD segments based on the flags. Readonly
1815 // segments come before writable segments. Then writable segments
1816 // with data come before writable segments without data. Then
1817 // executable segments come before non-executable segments. Then
1818 // the unlikely case of a non-readable segment comes before the
1819 // normal case of a readable segment. If there are multiple
1820 // segments with the same type and flags, we require that the
1821 // address be set, and we sort by virtual address and then physical
1823 if ((flags1
& elfcpp::PF_W
) != (flags2
& elfcpp::PF_W
))
1824 return (flags1
& elfcpp::PF_W
) == 0;
1825 if ((flags1
& elfcpp::PF_W
) != 0
1826 && seg1
->has_any_data_sections() != seg2
->has_any_data_sections())
1827 return seg1
->has_any_data_sections();
1828 if ((flags1
& elfcpp::PF_X
) != (flags2
& elfcpp::PF_X
))
1829 return (flags1
& elfcpp::PF_X
) != 0;
1830 if ((flags1
& elfcpp::PF_R
) != (flags2
& elfcpp::PF_R
))
1831 return (flags1
& elfcpp::PF_R
) == 0;
1833 // We shouldn't get here--we shouldn't create segments which we
1834 // can't distinguish.
1838 // Increase OFF so that it is congruent to ADDR modulo ABI_PAGESIZE.
1841 align_file_offset(off_t off
, uint64_t addr
, uint64_t abi_pagesize
)
1843 uint64_t unsigned_off
= off
;
1844 uint64_t aligned_off
= ((unsigned_off
& ~(abi_pagesize
- 1))
1845 | (addr
& (abi_pagesize
- 1)));
1846 if (aligned_off
< unsigned_off
)
1847 aligned_off
+= abi_pagesize
;
1851 // Set the file offsets of all the segments, and all the sections they
1852 // contain. They have all been created. LOAD_SEG must be be laid out
1853 // first. Return the offset of the data to follow.
1856 Layout::set_segment_offsets(const Target
* target
, Output_segment
* load_seg
,
1857 unsigned int *pshndx
)
1859 // Sort them into the final order.
1860 std::sort(this->segment_list_
.begin(), this->segment_list_
.end(),
1861 Layout::Compare_segments());
1863 // Find the PT_LOAD segments, and set their addresses and offsets
1864 // and their section's addresses and offsets.
1866 if (parameters
->options().user_set_Ttext())
1867 addr
= parameters
->options().Ttext();
1868 else if (parameters
->options().shared())
1871 addr
= target
->default_text_segment_address();
1874 // If LOAD_SEG is NULL, then the file header and segment headers
1875 // will not be loadable. But they still need to be at offset 0 in
1876 // the file. Set their offsets now.
1877 if (load_seg
== NULL
)
1879 for (Data_list::iterator p
= this->special_output_list_
.begin();
1880 p
!= this->special_output_list_
.end();
1883 off
= align_address(off
, (*p
)->addralign());
1884 (*p
)->set_address_and_file_offset(0, off
);
1885 off
+= (*p
)->data_size();
1889 const bool check_sections
= parameters
->options().check_sections();
1890 Output_segment
* last_load_segment
= NULL
;
1892 bool was_readonly
= false;
1893 for (Segment_list::iterator p
= this->segment_list_
.begin();
1894 p
!= this->segment_list_
.end();
1897 if ((*p
)->type() == elfcpp::PT_LOAD
)
1899 if (load_seg
!= NULL
&& load_seg
!= *p
)
1903 bool are_addresses_set
= (*p
)->are_addresses_set();
1904 if (are_addresses_set
)
1906 // When it comes to setting file offsets, we care about
1907 // the physical address.
1908 addr
= (*p
)->paddr();
1910 else if (parameters
->options().user_set_Tdata()
1911 && ((*p
)->flags() & elfcpp::PF_W
) != 0
1912 && (!parameters
->options().user_set_Tbss()
1913 || (*p
)->has_any_data_sections()))
1915 addr
= parameters
->options().Tdata();
1916 are_addresses_set
= true;
1918 else if (parameters
->options().user_set_Tbss()
1919 && ((*p
)->flags() & elfcpp::PF_W
) != 0
1920 && !(*p
)->has_any_data_sections())
1922 addr
= parameters
->options().Tbss();
1923 are_addresses_set
= true;
1926 uint64_t orig_addr
= addr
;
1927 uint64_t orig_off
= off
;
1929 uint64_t aligned_addr
= 0;
1930 uint64_t abi_pagesize
= target
->abi_pagesize();
1931 uint64_t common_pagesize
= target
->common_pagesize();
1933 if (!parameters
->options().nmagic()
1934 && !parameters
->options().omagic())
1935 (*p
)->set_minimum_p_align(common_pagesize
);
1937 if (!are_addresses_set
)
1939 // If the last segment was readonly, and this one is
1940 // not, then skip the address forward one page,
1941 // maintaining the same position within the page. This
1942 // lets us store both segments overlapping on a single
1943 // page in the file, but the loader will put them on
1944 // different pages in memory.
1946 addr
= align_address(addr
, (*p
)->maximum_alignment());
1947 aligned_addr
= addr
;
1949 if (was_readonly
&& ((*p
)->flags() & elfcpp::PF_W
) != 0)
1951 if ((addr
& (abi_pagesize
- 1)) != 0)
1952 addr
= addr
+ abi_pagesize
;
1955 off
= orig_off
+ ((addr
- orig_addr
) & (abi_pagesize
- 1));
1958 if (!parameters
->options().nmagic()
1959 && !parameters
->options().omagic())
1960 off
= align_file_offset(off
, addr
, abi_pagesize
);
1962 unsigned int shndx_hold
= *pshndx
;
1963 uint64_t new_addr
= (*p
)->set_section_addresses(this, false, addr
,
1966 // Now that we know the size of this segment, we may be able
1967 // to save a page in memory, at the cost of wasting some
1968 // file space, by instead aligning to the start of a new
1969 // page. Here we use the real machine page size rather than
1970 // the ABI mandated page size.
1972 if (!are_addresses_set
&& aligned_addr
!= addr
)
1974 uint64_t first_off
= (common_pagesize
1976 & (common_pagesize
- 1)));
1977 uint64_t last_off
= new_addr
& (common_pagesize
- 1);
1980 && ((aligned_addr
& ~ (common_pagesize
- 1))
1981 != (new_addr
& ~ (common_pagesize
- 1)))
1982 && first_off
+ last_off
<= common_pagesize
)
1984 *pshndx
= shndx_hold
;
1985 addr
= align_address(aligned_addr
, common_pagesize
);
1986 addr
= align_address(addr
, (*p
)->maximum_alignment());
1987 off
= orig_off
+ ((addr
- orig_addr
) & (abi_pagesize
- 1));
1988 off
= align_file_offset(off
, addr
, abi_pagesize
);
1989 new_addr
= (*p
)->set_section_addresses(this, true, addr
,
1996 if (((*p
)->flags() & elfcpp::PF_W
) == 0)
1997 was_readonly
= true;
1999 // Implement --check-sections. We know that the segments
2000 // are sorted by LMA.
2001 if (check_sections
&& last_load_segment
!= NULL
)
2003 gold_assert(last_load_segment
->paddr() <= (*p
)->paddr());
2004 if (last_load_segment
->paddr() + last_load_segment
->memsz()
2007 unsigned long long lb1
= last_load_segment
->paddr();
2008 unsigned long long le1
= lb1
+ last_load_segment
->memsz();
2009 unsigned long long lb2
= (*p
)->paddr();
2010 unsigned long long le2
= lb2
+ (*p
)->memsz();
2011 gold_error(_("load segment overlap [0x%llx -> 0x%llx] and "
2012 "[0x%llx -> 0x%llx]"),
2013 lb1
, le1
, lb2
, le2
);
2016 last_load_segment
= *p
;
2020 // Handle the non-PT_LOAD segments, setting their offsets from their
2021 // section's offsets.
2022 for (Segment_list::iterator p
= this->segment_list_
.begin();
2023 p
!= this->segment_list_
.end();
2026 if ((*p
)->type() != elfcpp::PT_LOAD
)
2030 // Set the TLS offsets for each section in the PT_TLS segment.
2031 if (this->tls_segment_
!= NULL
)
2032 this->tls_segment_
->set_tls_offsets();
2037 // Set the offsets of all the allocated sections when doing a
2038 // relocatable link. This does the same jobs as set_segment_offsets,
2039 // only for a relocatable link.
2042 Layout::set_relocatable_section_offsets(Output_data
* file_header
,
2043 unsigned int *pshndx
)
2047 file_header
->set_address_and_file_offset(0, 0);
2048 off
+= file_header
->data_size();
2050 for (Section_list::iterator p
= this->section_list_
.begin();
2051 p
!= this->section_list_
.end();
2054 // We skip unallocated sections here, except that group sections
2055 // have to come first.
2056 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) == 0
2057 && (*p
)->type() != elfcpp::SHT_GROUP
)
2060 off
= align_address(off
, (*p
)->addralign());
2062 // The linker script might have set the address.
2063 if (!(*p
)->is_address_valid())
2064 (*p
)->set_address(0);
2065 (*p
)->set_file_offset(off
);
2066 (*p
)->finalize_data_size();
2067 off
+= (*p
)->data_size();
2069 (*p
)->set_out_shndx(*pshndx
);
2076 // Set the file offset of all the sections not associated with a
2080 Layout::set_section_offsets(off_t off
, Layout::Section_offset_pass pass
)
2082 for (Section_list::iterator p
= this->unattached_section_list_
.begin();
2083 p
!= this->unattached_section_list_
.end();
2086 // The symtab section is handled in create_symtab_sections.
2087 if (*p
== this->symtab_section_
)
2090 // If we've already set the data size, don't set it again.
2091 if ((*p
)->is_offset_valid() && (*p
)->is_data_size_valid())
2094 if (pass
== BEFORE_INPUT_SECTIONS_PASS
2095 && (*p
)->requires_postprocessing())
2097 (*p
)->create_postprocessing_buffer();
2098 this->any_postprocessing_sections_
= true;
2101 if (pass
== BEFORE_INPUT_SECTIONS_PASS
2102 && (*p
)->after_input_sections())
2104 else if (pass
== POSTPROCESSING_SECTIONS_PASS
2105 && (!(*p
)->after_input_sections()
2106 || (*p
)->type() == elfcpp::SHT_STRTAB
))
2108 else if (pass
== STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
2109 && (!(*p
)->after_input_sections()
2110 || (*p
)->type() != elfcpp::SHT_STRTAB
))
2113 off
= align_address(off
, (*p
)->addralign());
2114 (*p
)->set_file_offset(off
);
2115 (*p
)->finalize_data_size();
2116 off
+= (*p
)->data_size();
2118 // At this point the name must be set.
2119 if (pass
!= STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
)
2120 this->namepool_
.add((*p
)->name(), false, NULL
);
2125 // Set the section indexes of all the sections not associated with a
2129 Layout::set_section_indexes(unsigned int shndx
)
2131 for (Section_list::iterator p
= this->unattached_section_list_
.begin();
2132 p
!= this->unattached_section_list_
.end();
2135 if (!(*p
)->has_out_shndx())
2137 (*p
)->set_out_shndx(shndx
);
2144 // Set the section addresses according to the linker script. This is
2145 // only called when we see a SECTIONS clause. This returns the
2146 // program segment which should hold the file header and segment
2147 // headers, if any. It will return NULL if they should not be in a
2151 Layout::set_section_addresses_from_script(Symbol_table
* symtab
)
2153 Script_sections
* ss
= this->script_options_
->script_sections();
2154 gold_assert(ss
->saw_sections_clause());
2156 // Place each orphaned output section in the script.
2157 for (Section_list::iterator p
= this->section_list_
.begin();
2158 p
!= this->section_list_
.end();
2161 if (!(*p
)->found_in_sections_clause())
2162 ss
->place_orphan(*p
);
2165 return this->script_options_
->set_section_addresses(symtab
, this);
2168 // Count the local symbols in the regular symbol table and the dynamic
2169 // symbol table, and build the respective string pools.
2172 Layout::count_local_symbols(const Task
* task
,
2173 const Input_objects
* input_objects
)
2175 // First, figure out an upper bound on the number of symbols we'll
2176 // be inserting into each pool. This helps us create the pools with
2177 // the right size, to avoid unnecessary hashtable resizing.
2178 unsigned int symbol_count
= 0;
2179 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
2180 p
!= input_objects
->relobj_end();
2182 symbol_count
+= (*p
)->local_symbol_count();
2184 // Go from "upper bound" to "estimate." We overcount for two
2185 // reasons: we double-count symbols that occur in more than one
2186 // object file, and we count symbols that are dropped from the
2187 // output. Add it all together and assume we overcount by 100%.
2190 // We assume all symbols will go into both the sympool and dynpool.
2191 this->sympool_
.reserve(symbol_count
);
2192 this->dynpool_
.reserve(symbol_count
);
2194 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
2195 p
!= input_objects
->relobj_end();
2198 Task_lock_obj
<Object
> tlo(task
, *p
);
2199 (*p
)->count_local_symbols(&this->sympool_
, &this->dynpool_
);
2203 // Create the symbol table sections. Here we also set the final
2204 // values of the symbols. At this point all the loadable sections are
2205 // fully laid out. SHNUM is the number of sections so far.
2208 Layout::create_symtab_sections(const Input_objects
* input_objects
,
2209 Symbol_table
* symtab
,
2215 if (parameters
->target().get_size() == 32)
2217 symsize
= elfcpp::Elf_sizes
<32>::sym_size
;
2220 else if (parameters
->target().get_size() == 64)
2222 symsize
= elfcpp::Elf_sizes
<64>::sym_size
;
2229 off
= align_address(off
, align
);
2230 off_t startoff
= off
;
2232 // Save space for the dummy symbol at the start of the section. We
2233 // never bother to write this out--it will just be left as zero.
2235 unsigned int local_symbol_index
= 1;
2237 // Add STT_SECTION symbols for each Output section which needs one.
2238 for (Section_list::iterator p
= this->section_list_
.begin();
2239 p
!= this->section_list_
.end();
2242 if (!(*p
)->needs_symtab_index())
2243 (*p
)->set_symtab_index(-1U);
2246 (*p
)->set_symtab_index(local_symbol_index
);
2247 ++local_symbol_index
;
2252 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
2253 p
!= input_objects
->relobj_end();
2256 unsigned int index
= (*p
)->finalize_local_symbols(local_symbol_index
,
2258 off
+= (index
- local_symbol_index
) * symsize
;
2259 local_symbol_index
= index
;
2262 unsigned int local_symcount
= local_symbol_index
;
2263 gold_assert(local_symcount
* symsize
== off
- startoff
);
2266 size_t dyn_global_index
;
2268 if (this->dynsym_section_
== NULL
)
2271 dyn_global_index
= 0;
2276 dyn_global_index
= this->dynsym_section_
->info();
2277 off_t locsize
= dyn_global_index
* this->dynsym_section_
->entsize();
2278 dynoff
= this->dynsym_section_
->offset() + locsize
;
2279 dyncount
= (this->dynsym_section_
->data_size() - locsize
) / symsize
;
2280 gold_assert(static_cast<off_t
>(dyncount
* symsize
)
2281 == this->dynsym_section_
->data_size() - locsize
);
2284 off
= symtab
->finalize(off
, dynoff
, dyn_global_index
, dyncount
,
2285 &this->sympool_
, &local_symcount
);
2287 if (!parameters
->options().strip_all())
2289 this->sympool_
.set_string_offsets();
2291 const char* symtab_name
= this->namepool_
.add(".symtab", false, NULL
);
2292 Output_section
* osymtab
= this->make_output_section(symtab_name
,
2295 this->symtab_section_
= osymtab
;
2297 Output_section_data
* pos
= new Output_data_fixed_space(off
- startoff
,
2300 osymtab
->add_output_section_data(pos
);
2302 // We generate a .symtab_shndx section if we have more than
2303 // SHN_LORESERVE sections. Technically it is possible that we
2304 // don't need one, because it is possible that there are no
2305 // symbols in any of sections with indexes larger than
2306 // SHN_LORESERVE. That is probably unusual, though, and it is
2307 // easier to always create one than to compute section indexes
2308 // twice (once here, once when writing out the symbols).
2309 if (shnum
>= elfcpp::SHN_LORESERVE
)
2311 const char* symtab_xindex_name
= this->namepool_
.add(".symtab_shndx",
2313 Output_section
* osymtab_xindex
=
2314 this->make_output_section(symtab_xindex_name
,
2315 elfcpp::SHT_SYMTAB_SHNDX
, 0);
2317 size_t symcount
= (off
- startoff
) / symsize
;
2318 this->symtab_xindex_
= new Output_symtab_xindex(symcount
);
2320 osymtab_xindex
->add_output_section_data(this->symtab_xindex_
);
2322 osymtab_xindex
->set_link_section(osymtab
);
2323 osymtab_xindex
->set_addralign(4);
2324 osymtab_xindex
->set_entsize(4);
2326 osymtab_xindex
->set_after_input_sections();
2328 // This tells the driver code to wait until the symbol table
2329 // has written out before writing out the postprocessing
2330 // sections, including the .symtab_shndx section.
2331 this->any_postprocessing_sections_
= true;
2334 const char* strtab_name
= this->namepool_
.add(".strtab", false, NULL
);
2335 Output_section
* ostrtab
= this->make_output_section(strtab_name
,
2339 Output_section_data
* pstr
= new Output_data_strtab(&this->sympool_
);
2340 ostrtab
->add_output_section_data(pstr
);
2342 osymtab
->set_file_offset(startoff
);
2343 osymtab
->finalize_data_size();
2344 osymtab
->set_link_section(ostrtab
);
2345 osymtab
->set_info(local_symcount
);
2346 osymtab
->set_entsize(symsize
);
2352 // Create the .shstrtab section, which holds the names of the
2353 // sections. At the time this is called, we have created all the
2354 // output sections except .shstrtab itself.
2357 Layout::create_shstrtab()
2359 // FIXME: We don't need to create a .shstrtab section if we are
2360 // stripping everything.
2362 const char* name
= this->namepool_
.add(".shstrtab", false, NULL
);
2364 Output_section
* os
= this->make_output_section(name
, elfcpp::SHT_STRTAB
, 0);
2366 // We can't write out this section until we've set all the section
2367 // names, and we don't set the names of compressed output sections
2368 // until relocations are complete.
2369 os
->set_after_input_sections();
2371 Output_section_data
* posd
= new Output_data_strtab(&this->namepool_
);
2372 os
->add_output_section_data(posd
);
2377 // Create the section headers. SIZE is 32 or 64. OFF is the file
2381 Layout::create_shdrs(const Output_section
* shstrtab_section
, off_t
* poff
)
2383 Output_section_headers
* oshdrs
;
2384 oshdrs
= new Output_section_headers(this,
2385 &this->segment_list_
,
2386 &this->section_list_
,
2387 &this->unattached_section_list_
,
2390 off_t off
= align_address(*poff
, oshdrs
->addralign());
2391 oshdrs
->set_address_and_file_offset(0, off
);
2392 off
+= oshdrs
->data_size();
2394 this->section_headers_
= oshdrs
;
2397 // Count the allocated sections.
2400 Layout::allocated_output_section_count() const
2402 size_t section_count
= 0;
2403 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
2404 p
!= this->segment_list_
.end();
2406 section_count
+= (*p
)->output_section_count();
2407 return section_count
;
2410 // Create the dynamic symbol table.
2413 Layout::create_dynamic_symtab(const Input_objects
* input_objects
,
2414 Symbol_table
* symtab
,
2415 Output_section
**pdynstr
,
2416 unsigned int* plocal_dynamic_count
,
2417 std::vector
<Symbol
*>* pdynamic_symbols
,
2418 Versions
* pversions
)
2420 // Count all the symbols in the dynamic symbol table, and set the
2421 // dynamic symbol indexes.
2423 // Skip symbol 0, which is always all zeroes.
2424 unsigned int index
= 1;
2426 // Add STT_SECTION symbols for each Output section which needs one.
2427 for (Section_list::iterator p
= this->section_list_
.begin();
2428 p
!= this->section_list_
.end();
2431 if (!(*p
)->needs_dynsym_index())
2432 (*p
)->set_dynsym_index(-1U);
2435 (*p
)->set_dynsym_index(index
);
2440 // Count the local symbols that need to go in the dynamic symbol table,
2441 // and set the dynamic symbol indexes.
2442 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
2443 p
!= input_objects
->relobj_end();
2446 unsigned int new_index
= (*p
)->set_local_dynsym_indexes(index
);
2450 unsigned int local_symcount
= index
;
2451 *plocal_dynamic_count
= local_symcount
;
2453 index
= symtab
->set_dynsym_indexes(index
, pdynamic_symbols
,
2454 &this->dynpool_
, pversions
);
2458 const int size
= parameters
->target().get_size();
2461 symsize
= elfcpp::Elf_sizes
<32>::sym_size
;
2464 else if (size
== 64)
2466 symsize
= elfcpp::Elf_sizes
<64>::sym_size
;
2472 // Create the dynamic symbol table section.
2474 Output_section
* dynsym
= this->choose_output_section(NULL
, ".dynsym",
2479 Output_section_data
* odata
= new Output_data_fixed_space(index
* symsize
,
2482 dynsym
->add_output_section_data(odata
);
2484 dynsym
->set_info(local_symcount
);
2485 dynsym
->set_entsize(symsize
);
2486 dynsym
->set_addralign(align
);
2488 this->dynsym_section_
= dynsym
;
2490 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
2491 odyn
->add_section_address(elfcpp::DT_SYMTAB
, dynsym
);
2492 odyn
->add_constant(elfcpp::DT_SYMENT
, symsize
);
2494 // If there are more than SHN_LORESERVE allocated sections, we
2495 // create a .dynsym_shndx section. It is possible that we don't
2496 // need one, because it is possible that there are no dynamic
2497 // symbols in any of the sections with indexes larger than
2498 // SHN_LORESERVE. This is probably unusual, though, and at this
2499 // time we don't know the actual section indexes so it is
2500 // inconvenient to check.
2501 if (this->allocated_output_section_count() >= elfcpp::SHN_LORESERVE
)
2503 Output_section
* dynsym_xindex
=
2504 this->choose_output_section(NULL
, ".dynsym_shndx",
2505 elfcpp::SHT_SYMTAB_SHNDX
,
2509 this->dynsym_xindex_
= new Output_symtab_xindex(index
);
2511 dynsym_xindex
->add_output_section_data(this->dynsym_xindex_
);
2513 dynsym_xindex
->set_link_section(dynsym
);
2514 dynsym_xindex
->set_addralign(4);
2515 dynsym_xindex
->set_entsize(4);
2517 dynsym_xindex
->set_after_input_sections();
2519 // This tells the driver code to wait until the symbol table has
2520 // written out before writing out the postprocessing sections,
2521 // including the .dynsym_shndx section.
2522 this->any_postprocessing_sections_
= true;
2525 // Create the dynamic string table section.
2527 Output_section
* dynstr
= this->choose_output_section(NULL
, ".dynstr",
2532 Output_section_data
* strdata
= new Output_data_strtab(&this->dynpool_
);
2533 dynstr
->add_output_section_data(strdata
);
2535 dynsym
->set_link_section(dynstr
);
2536 this->dynamic_section_
->set_link_section(dynstr
);
2538 odyn
->add_section_address(elfcpp::DT_STRTAB
, dynstr
);
2539 odyn
->add_section_size(elfcpp::DT_STRSZ
, dynstr
);
2543 // Create the hash tables.
2545 if (strcmp(parameters
->options().hash_style(), "sysv") == 0
2546 || strcmp(parameters
->options().hash_style(), "both") == 0)
2548 unsigned char* phash
;
2549 unsigned int hashlen
;
2550 Dynobj::create_elf_hash_table(*pdynamic_symbols
, local_symcount
,
2553 Output_section
* hashsec
= this->choose_output_section(NULL
, ".hash",
2558 Output_section_data
* hashdata
= new Output_data_const_buffer(phash
,
2562 hashsec
->add_output_section_data(hashdata
);
2564 hashsec
->set_link_section(dynsym
);
2565 hashsec
->set_entsize(4);
2567 odyn
->add_section_address(elfcpp::DT_HASH
, hashsec
);
2570 if (strcmp(parameters
->options().hash_style(), "gnu") == 0
2571 || strcmp(parameters
->options().hash_style(), "both") == 0)
2573 unsigned char* phash
;
2574 unsigned int hashlen
;
2575 Dynobj::create_gnu_hash_table(*pdynamic_symbols
, local_symcount
,
2578 Output_section
* hashsec
= this->choose_output_section(NULL
, ".gnu.hash",
2579 elfcpp::SHT_GNU_HASH
,
2583 Output_section_data
* hashdata
= new Output_data_const_buffer(phash
,
2587 hashsec
->add_output_section_data(hashdata
);
2589 hashsec
->set_link_section(dynsym
);
2590 hashsec
->set_entsize(4);
2592 odyn
->add_section_address(elfcpp::DT_GNU_HASH
, hashsec
);
2596 // Assign offsets to each local portion of the dynamic symbol table.
2599 Layout::assign_local_dynsym_offsets(const Input_objects
* input_objects
)
2601 Output_section
* dynsym
= this->dynsym_section_
;
2602 gold_assert(dynsym
!= NULL
);
2604 off_t off
= dynsym
->offset();
2606 // Skip the dummy symbol at the start of the section.
2607 off
+= dynsym
->entsize();
2609 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
2610 p
!= input_objects
->relobj_end();
2613 unsigned int count
= (*p
)->set_local_dynsym_offset(off
);
2614 off
+= count
* dynsym
->entsize();
2618 // Create the version sections.
2621 Layout::create_version_sections(const Versions
* versions
,
2622 const Symbol_table
* symtab
,
2623 unsigned int local_symcount
,
2624 const std::vector
<Symbol
*>& dynamic_symbols
,
2625 const Output_section
* dynstr
)
2627 if (!versions
->any_defs() && !versions
->any_needs())
2630 switch (parameters
->size_and_endianness())
2632 #ifdef HAVE_TARGET_32_LITTLE
2633 case Parameters::TARGET_32_LITTLE
:
2634 this->sized_create_version_sections
<32, false>(versions
, symtab
,
2636 dynamic_symbols
, dynstr
);
2639 #ifdef HAVE_TARGET_32_BIG
2640 case Parameters::TARGET_32_BIG
:
2641 this->sized_create_version_sections
<32, true>(versions
, symtab
,
2643 dynamic_symbols
, dynstr
);
2646 #ifdef HAVE_TARGET_64_LITTLE
2647 case Parameters::TARGET_64_LITTLE
:
2648 this->sized_create_version_sections
<64, false>(versions
, symtab
,
2650 dynamic_symbols
, dynstr
);
2653 #ifdef HAVE_TARGET_64_BIG
2654 case Parameters::TARGET_64_BIG
:
2655 this->sized_create_version_sections
<64, true>(versions
, symtab
,
2657 dynamic_symbols
, dynstr
);
2665 // Create the version sections, sized version.
2667 template<int size
, bool big_endian
>
2669 Layout::sized_create_version_sections(
2670 const Versions
* versions
,
2671 const Symbol_table
* symtab
,
2672 unsigned int local_symcount
,
2673 const std::vector
<Symbol
*>& dynamic_symbols
,
2674 const Output_section
* dynstr
)
2676 Output_section
* vsec
= this->choose_output_section(NULL
, ".gnu.version",
2677 elfcpp::SHT_GNU_versym
,
2681 unsigned char* vbuf
;
2683 versions
->symbol_section_contents
<size
, big_endian
>(symtab
, &this->dynpool_
,
2688 Output_section_data
* vdata
= new Output_data_const_buffer(vbuf
, vsize
, 2,
2691 vsec
->add_output_section_data(vdata
);
2692 vsec
->set_entsize(2);
2693 vsec
->set_link_section(this->dynsym_section_
);
2695 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
2696 odyn
->add_section_address(elfcpp::DT_VERSYM
, vsec
);
2698 if (versions
->any_defs())
2700 Output_section
* vdsec
;
2701 vdsec
= this->choose_output_section(NULL
, ".gnu.version_d",
2702 elfcpp::SHT_GNU_verdef
,
2706 unsigned char* vdbuf
;
2707 unsigned int vdsize
;
2708 unsigned int vdentries
;
2709 versions
->def_section_contents
<size
, big_endian
>(&this->dynpool_
, &vdbuf
,
2710 &vdsize
, &vdentries
);
2712 Output_section_data
* vddata
=
2713 new Output_data_const_buffer(vdbuf
, vdsize
, 4, "** version defs");
2715 vdsec
->add_output_section_data(vddata
);
2716 vdsec
->set_link_section(dynstr
);
2717 vdsec
->set_info(vdentries
);
2719 odyn
->add_section_address(elfcpp::DT_VERDEF
, vdsec
);
2720 odyn
->add_constant(elfcpp::DT_VERDEFNUM
, vdentries
);
2723 if (versions
->any_needs())
2725 Output_section
* vnsec
;
2726 vnsec
= this->choose_output_section(NULL
, ".gnu.version_r",
2727 elfcpp::SHT_GNU_verneed
,
2731 unsigned char* vnbuf
;
2732 unsigned int vnsize
;
2733 unsigned int vnentries
;
2734 versions
->need_section_contents
<size
, big_endian
>(&this->dynpool_
,
2738 Output_section_data
* vndata
=
2739 new Output_data_const_buffer(vnbuf
, vnsize
, 4, "** version refs");
2741 vnsec
->add_output_section_data(vndata
);
2742 vnsec
->set_link_section(dynstr
);
2743 vnsec
->set_info(vnentries
);
2745 odyn
->add_section_address(elfcpp::DT_VERNEED
, vnsec
);
2746 odyn
->add_constant(elfcpp::DT_VERNEEDNUM
, vnentries
);
2750 // Create the .interp section and PT_INTERP segment.
2753 Layout::create_interp(const Target
* target
)
2755 const char* interp
= parameters
->options().dynamic_linker();
2758 interp
= target
->dynamic_linker();
2759 gold_assert(interp
!= NULL
);
2762 size_t len
= strlen(interp
) + 1;
2764 Output_section_data
* odata
= new Output_data_const(interp
, len
, 1);
2766 Output_section
* osec
= this->choose_output_section(NULL
, ".interp",
2767 elfcpp::SHT_PROGBITS
,
2770 osec
->add_output_section_data(odata
);
2772 if (!this->script_options_
->saw_phdrs_clause())
2774 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_INTERP
,
2776 oseg
->add_output_section(osec
, elfcpp::PF_R
);
2780 // Finish the .dynamic section and PT_DYNAMIC segment.
2783 Layout::finish_dynamic_section(const Input_objects
* input_objects
,
2784 const Symbol_table
* symtab
)
2786 if (!this->script_options_
->saw_phdrs_clause())
2788 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_DYNAMIC
,
2791 oseg
->add_output_section(this->dynamic_section_
,
2792 elfcpp::PF_R
| elfcpp::PF_W
);
2795 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
2797 for (Input_objects::Dynobj_iterator p
= input_objects
->dynobj_begin();
2798 p
!= input_objects
->dynobj_end();
2801 // FIXME: Handle --as-needed.
2802 odyn
->add_string(elfcpp::DT_NEEDED
, (*p
)->soname());
2805 if (parameters
->options().shared())
2807 const char* soname
= parameters
->options().soname();
2809 odyn
->add_string(elfcpp::DT_SONAME
, soname
);
2812 // FIXME: Support --init and --fini.
2813 Symbol
* sym
= symtab
->lookup("_init");
2814 if (sym
!= NULL
&& sym
->is_defined() && !sym
->is_from_dynobj())
2815 odyn
->add_symbol(elfcpp::DT_INIT
, sym
);
2817 sym
= symtab
->lookup("_fini");
2818 if (sym
!= NULL
&& sym
->is_defined() && !sym
->is_from_dynobj())
2819 odyn
->add_symbol(elfcpp::DT_FINI
, sym
);
2821 // FIXME: Support DT_INIT_ARRAY and DT_FINI_ARRAY.
2823 // Add a DT_RPATH entry if needed.
2824 const General_options::Dir_list
& rpath(parameters
->options().rpath());
2827 std::string rpath_val
;
2828 for (General_options::Dir_list::const_iterator p
= rpath
.begin();
2832 if (rpath_val
.empty())
2833 rpath_val
= p
->name();
2836 // Eliminate duplicates.
2837 General_options::Dir_list::const_iterator q
;
2838 for (q
= rpath
.begin(); q
!= p
; ++q
)
2839 if (q
->name() == p
->name())
2844 rpath_val
+= p
->name();
2849 odyn
->add_string(elfcpp::DT_RPATH
, rpath_val
);
2850 if (parameters
->options().enable_new_dtags())
2851 odyn
->add_string(elfcpp::DT_RUNPATH
, rpath_val
);
2854 // Look for text segments that have dynamic relocations.
2855 bool have_textrel
= false;
2856 if (!this->script_options_
->saw_sections_clause())
2858 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
2859 p
!= this->segment_list_
.end();
2862 if (((*p
)->flags() & elfcpp::PF_W
) == 0
2863 && (*p
)->dynamic_reloc_count() > 0)
2865 have_textrel
= true;
2872 // We don't know the section -> segment mapping, so we are
2873 // conservative and just look for readonly sections with
2874 // relocations. If those sections wind up in writable segments,
2875 // then we have created an unnecessary DT_TEXTREL entry.
2876 for (Section_list::const_iterator p
= this->section_list_
.begin();
2877 p
!= this->section_list_
.end();
2880 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) != 0
2881 && ((*p
)->flags() & elfcpp::SHF_WRITE
) == 0
2882 && ((*p
)->dynamic_reloc_count() > 0))
2884 have_textrel
= true;
2890 // Add a DT_FLAGS entry. We add it even if no flags are set so that
2891 // post-link tools can easily modify these flags if desired.
2892 unsigned int flags
= 0;
2895 // Add a DT_TEXTREL for compatibility with older loaders.
2896 odyn
->add_constant(elfcpp::DT_TEXTREL
, 0);
2897 flags
|= elfcpp::DF_TEXTREL
;
2899 if (parameters
->options().shared() && this->has_static_tls())
2900 flags
|= elfcpp::DF_STATIC_TLS
;
2901 if (parameters
->options().origin())
2902 flags
|= elfcpp::DF_ORIGIN
;
2903 if (parameters
->options().now())
2904 flags
|= elfcpp::DF_BIND_NOW
;
2905 odyn
->add_constant(elfcpp::DT_FLAGS
, flags
);
2908 if (parameters
->options().initfirst())
2909 flags
|= elfcpp::DF_1_INITFIRST
;
2910 if (parameters
->options().interpose())
2911 flags
|= elfcpp::DF_1_INTERPOSE
;
2912 if (parameters
->options().loadfltr())
2913 flags
|= elfcpp::DF_1_LOADFLTR
;
2914 if (parameters
->options().nodefaultlib())
2915 flags
|= elfcpp::DF_1_NODEFLIB
;
2916 if (parameters
->options().nodelete())
2917 flags
|= elfcpp::DF_1_NODELETE
;
2918 if (parameters
->options().nodlopen())
2919 flags
|= elfcpp::DF_1_NOOPEN
;
2920 if (parameters
->options().nodump())
2921 flags
|= elfcpp::DF_1_NODUMP
;
2922 if (!parameters
->options().shared())
2923 flags
&= ~(elfcpp::DF_1_INITFIRST
2924 | elfcpp::DF_1_NODELETE
2925 | elfcpp::DF_1_NOOPEN
);
2926 if (parameters
->options().origin())
2927 flags
|= elfcpp::DF_1_ORIGIN
;
2928 if (parameters
->options().now())
2929 flags
|= elfcpp::DF_1_NOW
;
2931 odyn
->add_constant(elfcpp::DT_FLAGS_1
, flags
);
2934 // The mapping of input section name prefixes to output section names.
2935 // In some cases one prefix is itself a prefix of another prefix; in
2936 // such a case the longer prefix must come first. These prefixes are
2937 // based on the GNU linker default ELF linker script.
2939 #define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 }
2940 const Layout::Section_name_mapping
Layout::section_name_mapping
[] =
2942 MAPPING_INIT(".text.", ".text"),
2943 MAPPING_INIT(".ctors.", ".ctors"),
2944 MAPPING_INIT(".dtors.", ".dtors"),
2945 MAPPING_INIT(".rodata.", ".rodata"),
2946 MAPPING_INIT(".data.rel.ro.local", ".data.rel.ro.local"),
2947 MAPPING_INIT(".data.rel.ro", ".data.rel.ro"),
2948 MAPPING_INIT(".data.", ".data"),
2949 MAPPING_INIT(".bss.", ".bss"),
2950 MAPPING_INIT(".tdata.", ".tdata"),
2951 MAPPING_INIT(".tbss.", ".tbss"),
2952 MAPPING_INIT(".init_array.", ".init_array"),
2953 MAPPING_INIT(".fini_array.", ".fini_array"),
2954 MAPPING_INIT(".sdata.", ".sdata"),
2955 MAPPING_INIT(".sbss.", ".sbss"),
2956 // FIXME: In the GNU linker, .sbss2 and .sdata2 are handled
2957 // differently depending on whether it is creating a shared library.
2958 MAPPING_INIT(".sdata2.", ".sdata"),
2959 MAPPING_INIT(".sbss2.", ".sbss"),
2960 MAPPING_INIT(".lrodata.", ".lrodata"),
2961 MAPPING_INIT(".ldata.", ".ldata"),
2962 MAPPING_INIT(".lbss.", ".lbss"),
2963 MAPPING_INIT(".gcc_except_table.", ".gcc_except_table"),
2964 MAPPING_INIT(".gnu.linkonce.d.rel.ro.local.", ".data.rel.ro.local"),
2965 MAPPING_INIT(".gnu.linkonce.d.rel.ro.", ".data.rel.ro"),
2966 MAPPING_INIT(".gnu.linkonce.t.", ".text"),
2967 MAPPING_INIT(".gnu.linkonce.r.", ".rodata"),
2968 MAPPING_INIT(".gnu.linkonce.d.", ".data"),
2969 MAPPING_INIT(".gnu.linkonce.b.", ".bss"),
2970 MAPPING_INIT(".gnu.linkonce.s.", ".sdata"),
2971 MAPPING_INIT(".gnu.linkonce.sb.", ".sbss"),
2972 MAPPING_INIT(".gnu.linkonce.s2.", ".sdata"),
2973 MAPPING_INIT(".gnu.linkonce.sb2.", ".sbss"),
2974 MAPPING_INIT(".gnu.linkonce.wi.", ".debug_info"),
2975 MAPPING_INIT(".gnu.linkonce.td.", ".tdata"),
2976 MAPPING_INIT(".gnu.linkonce.tb.", ".tbss"),
2977 MAPPING_INIT(".gnu.linkonce.lr.", ".lrodata"),
2978 MAPPING_INIT(".gnu.linkonce.l.", ".ldata"),
2979 MAPPING_INIT(".gnu.linkonce.lb.", ".lbss"),
2980 MAPPING_INIT(".ARM.extab.", ".ARM.extab"),
2981 MAPPING_INIT(".gnu.linkonce.armextab.", ".ARM.extab"),
2982 MAPPING_INIT(".ARM.exidx.", ".ARM.exidx"),
2983 MAPPING_INIT(".gnu.linkonce.armexidx.", ".ARM.exidx"),
2987 const int Layout::section_name_mapping_count
=
2988 (sizeof(Layout::section_name_mapping
)
2989 / sizeof(Layout::section_name_mapping
[0]));
2991 // Choose the output section name to use given an input section name.
2992 // Set *PLEN to the length of the name. *PLEN is initialized to the
2996 Layout::output_section_name(const char* name
, size_t* plen
)
2998 // gcc 4.3 generates the following sorts of section names when it
2999 // needs a section name specific to a function:
3005 // .data.rel.local.FN
3007 // .data.rel.ro.local.FN
3014 // The GNU linker maps all of those to the part before the .FN,
3015 // except that .data.rel.local.FN is mapped to .data, and
3016 // .data.rel.ro.local.FN is mapped to .data.rel.ro. The sections
3017 // beginning with .data.rel.ro.local are grouped together.
3019 // For an anonymous namespace, the string FN can contain a '.'.
3021 // Also of interest: .rodata.strN.N, .rodata.cstN, both of which the
3022 // GNU linker maps to .rodata.
3024 // The .data.rel.ro sections are used with -z relro. The sections
3025 // are recognized by name. We use the same names that the GNU
3026 // linker does for these sections.
3028 // It is hard to handle this in a principled way, so we don't even
3029 // try. We use a table of mappings. If the input section name is
3030 // not found in the table, we simply use it as the output section
3033 const Section_name_mapping
* psnm
= section_name_mapping
;
3034 for (int i
= 0; i
< section_name_mapping_count
; ++i
, ++psnm
)
3036 if (strncmp(name
, psnm
->from
, psnm
->fromlen
) == 0)
3038 *plen
= psnm
->tolen
;
3046 // Check if a comdat group or .gnu.linkonce section with the given
3047 // NAME is selected for the link. If there is already a section,
3048 // *KEPT_SECTION is set to point to the existing section and the
3049 // function returns false. Otherwise, OBJECT, SHNDX, IS_COMDAT, and
3050 // IS_GROUP_NAME are recorded for this NAME in the layout object,
3051 // *KEPT_SECTION is set to the internal copy and the function returns
3055 Layout::find_or_add_kept_section(const std::string
& name
,
3060 Kept_section
** kept_section
)
3062 // It's normal to see a couple of entries here, for the x86 thunk
3063 // sections. If we see more than a few, we're linking a C++
3064 // program, and we resize to get more space to minimize rehashing.
3065 if (this->signatures_
.size() > 4
3066 && !this->resized_signatures_
)
3068 reserve_unordered_map(&this->signatures_
,
3069 this->number_of_input_files_
* 64);
3070 this->resized_signatures_
= true;
3073 Kept_section candidate
;
3074 std::pair
<Signatures::iterator
, bool> ins
=
3075 this->signatures_
.insert(std::make_pair(name
, candidate
));
3077 if (kept_section
!= NULL
)
3078 *kept_section
= &ins
.first
->second
;
3081 // This is the first time we've seen this signature.
3082 ins
.first
->second
.set_object(object
);
3083 ins
.first
->second
.set_shndx(shndx
);
3085 ins
.first
->second
.set_is_comdat();
3087 ins
.first
->second
.set_is_group_name();
3091 // We have already seen this signature.
3093 if (ins
.first
->second
.is_group_name())
3095 // We've already seen a real section group with this signature.
3096 // If the kept group is from a plugin object, and we're in the
3097 // replacement phase, accept the new one as a replacement.
3098 if (ins
.first
->second
.object() == NULL
3099 && parameters
->options().plugins()->in_replacement_phase())
3101 ins
.first
->second
.set_object(object
);
3102 ins
.first
->second
.set_shndx(shndx
);
3107 else if (is_group_name
)
3109 // This is a real section group, and we've already seen a
3110 // linkonce section with this signature. Record that we've seen
3111 // a section group, and don't include this section group.
3112 ins
.first
->second
.set_is_group_name();
3117 // We've already seen a linkonce section and this is a linkonce
3118 // section. These don't block each other--this may be the same
3119 // symbol name with different section types.
3124 // Store the allocated sections into the section list.
3127 Layout::get_allocated_sections(Section_list
* section_list
) const
3129 for (Section_list::const_iterator p
= this->section_list_
.begin();
3130 p
!= this->section_list_
.end();
3132 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) != 0)
3133 section_list
->push_back(*p
);
3136 // Create an output segment.
3139 Layout::make_output_segment(elfcpp::Elf_Word type
, elfcpp::Elf_Word flags
)
3141 gold_assert(!parameters
->options().relocatable());
3142 Output_segment
* oseg
= new Output_segment(type
, flags
);
3143 this->segment_list_
.push_back(oseg
);
3145 if (type
== elfcpp::PT_TLS
)
3146 this->tls_segment_
= oseg
;
3147 else if (type
== elfcpp::PT_GNU_RELRO
)
3148 this->relro_segment_
= oseg
;
3153 // Write out the Output_sections. Most won't have anything to write,
3154 // since most of the data will come from input sections which are
3155 // handled elsewhere. But some Output_sections do have Output_data.
3158 Layout::write_output_sections(Output_file
* of
) const
3160 for (Section_list::const_iterator p
= this->section_list_
.begin();
3161 p
!= this->section_list_
.end();
3164 if (!(*p
)->after_input_sections())
3169 // Write out data not associated with a section or the symbol table.
3172 Layout::write_data(const Symbol_table
* symtab
, Output_file
* of
) const
3174 if (!parameters
->options().strip_all())
3176 const Output_section
* symtab_section
= this->symtab_section_
;
3177 for (Section_list::const_iterator p
= this->section_list_
.begin();
3178 p
!= this->section_list_
.end();
3181 if ((*p
)->needs_symtab_index())
3183 gold_assert(symtab_section
!= NULL
);
3184 unsigned int index
= (*p
)->symtab_index();
3185 gold_assert(index
> 0 && index
!= -1U);
3186 off_t off
= (symtab_section
->offset()
3187 + index
* symtab_section
->entsize());
3188 symtab
->write_section_symbol(*p
, this->symtab_xindex_
, of
, off
);
3193 const Output_section
* dynsym_section
= this->dynsym_section_
;
3194 for (Section_list::const_iterator p
= this->section_list_
.begin();
3195 p
!= this->section_list_
.end();
3198 if ((*p
)->needs_dynsym_index())
3200 gold_assert(dynsym_section
!= NULL
);
3201 unsigned int index
= (*p
)->dynsym_index();
3202 gold_assert(index
> 0 && index
!= -1U);
3203 off_t off
= (dynsym_section
->offset()
3204 + index
* dynsym_section
->entsize());
3205 symtab
->write_section_symbol(*p
, this->dynsym_xindex_
, of
, off
);
3209 // Write out the Output_data which are not in an Output_section.
3210 for (Data_list::const_iterator p
= this->special_output_list_
.begin();
3211 p
!= this->special_output_list_
.end();
3216 // Write out the Output_sections which can only be written after the
3217 // input sections are complete.
3220 Layout::write_sections_after_input_sections(Output_file
* of
)
3222 // Determine the final section offsets, and thus the final output
3223 // file size. Note we finalize the .shstrab last, to allow the
3224 // after_input_section sections to modify their section-names before
3226 if (this->any_postprocessing_sections_
)
3228 off_t off
= this->output_file_size_
;
3229 off
= this->set_section_offsets(off
, POSTPROCESSING_SECTIONS_PASS
);
3231 // Now that we've finalized the names, we can finalize the shstrab.
3233 this->set_section_offsets(off
,
3234 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
);
3236 if (off
> this->output_file_size_
)
3239 this->output_file_size_
= off
;
3243 for (Section_list::const_iterator p
= this->section_list_
.begin();
3244 p
!= this->section_list_
.end();
3247 if ((*p
)->after_input_sections())
3251 this->section_headers_
->write(of
);
3254 // If the build ID requires computing a checksum, do so here, and
3255 // write it out. We compute a checksum over the entire file because
3256 // that is simplest.
3259 Layout::write_build_id(Output_file
* of
) const
3261 if (this->build_id_note_
== NULL
)
3264 const unsigned char* iv
= of
->get_input_view(0, this->output_file_size_
);
3266 unsigned char* ov
= of
->get_output_view(this->build_id_note_
->offset(),
3267 this->build_id_note_
->data_size());
3269 const char* style
= parameters
->options().build_id();
3270 if (strcmp(style
, "sha1") == 0)
3273 sha1_init_ctx(&ctx
);
3274 sha1_process_bytes(iv
, this->output_file_size_
, &ctx
);
3275 sha1_finish_ctx(&ctx
, ov
);
3277 else if (strcmp(style
, "md5") == 0)
3281 md5_process_bytes(iv
, this->output_file_size_
, &ctx
);
3282 md5_finish_ctx(&ctx
, ov
);
3287 of
->write_output_view(this->build_id_note_
->offset(),
3288 this->build_id_note_
->data_size(),
3291 of
->free_input_view(0, this->output_file_size_
, iv
);
3294 // Write out a binary file. This is called after the link is
3295 // complete. IN is the temporary output file we used to generate the
3296 // ELF code. We simply walk through the segments, read them from
3297 // their file offset in IN, and write them to their load address in
3298 // the output file. FIXME: with a bit more work, we could support
3299 // S-records and/or Intel hex format here.
3302 Layout::write_binary(Output_file
* in
) const
3304 gold_assert(parameters
->options().oformat_enum()
3305 == General_options::OBJECT_FORMAT_BINARY
);
3307 // Get the size of the binary file.
3308 uint64_t max_load_address
= 0;
3309 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
3310 p
!= this->segment_list_
.end();
3313 if ((*p
)->type() == elfcpp::PT_LOAD
&& (*p
)->filesz() > 0)
3315 uint64_t max_paddr
= (*p
)->paddr() + (*p
)->filesz();
3316 if (max_paddr
> max_load_address
)
3317 max_load_address
= max_paddr
;
3321 Output_file
out(parameters
->options().output_file_name());
3322 out
.open(max_load_address
);
3324 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
3325 p
!= this->segment_list_
.end();
3328 if ((*p
)->type() == elfcpp::PT_LOAD
&& (*p
)->filesz() > 0)
3330 const unsigned char* vin
= in
->get_input_view((*p
)->offset(),
3332 unsigned char* vout
= out
.get_output_view((*p
)->paddr(),
3334 memcpy(vout
, vin
, (*p
)->filesz());
3335 out
.write_output_view((*p
)->paddr(), (*p
)->filesz(), vout
);
3336 in
->free_input_view((*p
)->offset(), (*p
)->filesz(), vin
);
3343 // Print the output sections to the map file.
3346 Layout::print_to_mapfile(Mapfile
* mapfile
) const
3348 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
3349 p
!= this->segment_list_
.end();
3351 (*p
)->print_sections_to_mapfile(mapfile
);
3354 // Print statistical information to stderr. This is used for --stats.
3357 Layout::print_stats() const
3359 this->namepool_
.print_stats("section name pool");
3360 this->sympool_
.print_stats("output symbol name pool");
3361 this->dynpool_
.print_stats("dynamic name pool");
3363 for (Section_list::const_iterator p
= this->section_list_
.begin();
3364 p
!= this->section_list_
.end();
3366 (*p
)->print_merge_stats();
3369 // Write_sections_task methods.
3371 // We can always run this task.
3374 Write_sections_task::is_runnable()
3379 // We need to unlock both OUTPUT_SECTIONS_BLOCKER and FINAL_BLOCKER
3383 Write_sections_task::locks(Task_locker
* tl
)
3385 tl
->add(this, this->output_sections_blocker_
);
3386 tl
->add(this, this->final_blocker_
);
3389 // Run the task--write out the data.
3392 Write_sections_task::run(Workqueue
*)
3394 this->layout_
->write_output_sections(this->of_
);
3397 // Write_data_task methods.
3399 // We can always run this task.
3402 Write_data_task::is_runnable()
3407 // We need to unlock FINAL_BLOCKER when finished.
3410 Write_data_task::locks(Task_locker
* tl
)
3412 tl
->add(this, this->final_blocker_
);
3415 // Run the task--write out the data.
3418 Write_data_task::run(Workqueue
*)
3420 this->layout_
->write_data(this->symtab_
, this->of_
);
3423 // Write_symbols_task methods.
3425 // We can always run this task.
3428 Write_symbols_task::is_runnable()
3433 // We need to unlock FINAL_BLOCKER when finished.
3436 Write_symbols_task::locks(Task_locker
* tl
)
3438 tl
->add(this, this->final_blocker_
);
3441 // Run the task--write out the symbols.
3444 Write_symbols_task::run(Workqueue
*)
3446 this->symtab_
->write_globals(this->sympool_
, this->dynpool_
,
3447 this->layout_
->symtab_xindex(),
3448 this->layout_
->dynsym_xindex(), this->of_
);
3451 // Write_after_input_sections_task methods.
3453 // We can only run this task after the input sections have completed.
3456 Write_after_input_sections_task::is_runnable()
3458 if (this->input_sections_blocker_
->is_blocked())
3459 return this->input_sections_blocker_
;
3463 // We need to unlock FINAL_BLOCKER when finished.
3466 Write_after_input_sections_task::locks(Task_locker
* tl
)
3468 tl
->add(this, this->final_blocker_
);
3474 Write_after_input_sections_task::run(Workqueue
*)
3476 this->layout_
->write_sections_after_input_sections(this->of_
);
3479 // Close_task_runner methods.
3481 // Run the task--close the file.
3484 Close_task_runner::run(Workqueue
*, const Task
*)
3486 // If we need to compute a checksum for the BUILD if, we do so here.
3487 this->layout_
->write_build_id(this->of_
);
3489 // If we've been asked to create a binary file, we do so here.
3490 if (this->options_
->oformat_enum() != General_options::OBJECT_FORMAT_ELF
)
3491 this->layout_
->write_binary(this->of_
);
3496 // Instantiate the templates we need. We could use the configure
3497 // script to restrict this to only the ones for implemented targets.
3499 #ifdef HAVE_TARGET_32_LITTLE
3502 Layout::layout
<32, false>(Sized_relobj
<32, false>* object
, unsigned int shndx
,
3504 const elfcpp::Shdr
<32, false>& shdr
,
3505 unsigned int, unsigned int, off_t
*);
3508 #ifdef HAVE_TARGET_32_BIG
3511 Layout::layout
<32, true>(Sized_relobj
<32, true>* object
, unsigned int shndx
,
3513 const elfcpp::Shdr
<32, true>& shdr
,
3514 unsigned int, unsigned int, off_t
*);
3517 #ifdef HAVE_TARGET_64_LITTLE
3520 Layout::layout
<64, false>(Sized_relobj
<64, false>* object
, unsigned int shndx
,
3522 const elfcpp::Shdr
<64, false>& shdr
,
3523 unsigned int, unsigned int, off_t
*);
3526 #ifdef HAVE_TARGET_64_BIG
3529 Layout::layout
<64, true>(Sized_relobj
<64, true>* object
, unsigned int shndx
,
3531 const elfcpp::Shdr
<64, true>& shdr
,
3532 unsigned int, unsigned int, off_t
*);
3535 #ifdef HAVE_TARGET_32_LITTLE
3538 Layout::layout_reloc
<32, false>(Sized_relobj
<32, false>* object
,
3539 unsigned int reloc_shndx
,
3540 const elfcpp::Shdr
<32, false>& shdr
,
3541 Output_section
* data_section
,
3542 Relocatable_relocs
* rr
);
3545 #ifdef HAVE_TARGET_32_BIG
3548 Layout::layout_reloc
<32, true>(Sized_relobj
<32, true>* object
,
3549 unsigned int reloc_shndx
,
3550 const elfcpp::Shdr
<32, true>& shdr
,
3551 Output_section
* data_section
,
3552 Relocatable_relocs
* rr
);
3555 #ifdef HAVE_TARGET_64_LITTLE
3558 Layout::layout_reloc
<64, false>(Sized_relobj
<64, false>* object
,
3559 unsigned int reloc_shndx
,
3560 const elfcpp::Shdr
<64, false>& shdr
,
3561 Output_section
* data_section
,
3562 Relocatable_relocs
* rr
);
3565 #ifdef HAVE_TARGET_64_BIG
3568 Layout::layout_reloc
<64, true>(Sized_relobj
<64, true>* object
,
3569 unsigned int reloc_shndx
,
3570 const elfcpp::Shdr
<64, true>& shdr
,
3571 Output_section
* data_section
,
3572 Relocatable_relocs
* rr
);
3575 #ifdef HAVE_TARGET_32_LITTLE
3578 Layout::layout_group
<32, false>(Symbol_table
* symtab
,
3579 Sized_relobj
<32, false>* object
,
3581 const char* group_section_name
,
3582 const char* signature
,
3583 const elfcpp::Shdr
<32, false>& shdr
,
3584 elfcpp::Elf_Word flags
,
3585 std::vector
<unsigned int>* shndxes
);
3588 #ifdef HAVE_TARGET_32_BIG
3591 Layout::layout_group
<32, true>(Symbol_table
* symtab
,
3592 Sized_relobj
<32, true>* object
,
3594 const char* group_section_name
,
3595 const char* signature
,
3596 const elfcpp::Shdr
<32, true>& shdr
,
3597 elfcpp::Elf_Word flags
,
3598 std::vector
<unsigned int>* shndxes
);
3601 #ifdef HAVE_TARGET_64_LITTLE
3604 Layout::layout_group
<64, false>(Symbol_table
* symtab
,
3605 Sized_relobj
<64, false>* object
,
3607 const char* group_section_name
,
3608 const char* signature
,
3609 const elfcpp::Shdr
<64, false>& shdr
,
3610 elfcpp::Elf_Word flags
,
3611 std::vector
<unsigned int>* shndxes
);
3614 #ifdef HAVE_TARGET_64_BIG
3617 Layout::layout_group
<64, true>(Symbol_table
* symtab
,
3618 Sized_relobj
<64, true>* object
,
3620 const char* group_section_name
,
3621 const char* signature
,
3622 const elfcpp::Shdr
<64, true>& shdr
,
3623 elfcpp::Elf_Word flags
,
3624 std::vector
<unsigned int>* shndxes
);
3627 #ifdef HAVE_TARGET_32_LITTLE
3630 Layout::layout_eh_frame
<32, false>(Sized_relobj
<32, false>* object
,
3631 const unsigned char* symbols
,
3633 const unsigned char* symbol_names
,
3634 off_t symbol_names_size
,
3636 const elfcpp::Shdr
<32, false>& shdr
,
3637 unsigned int reloc_shndx
,
3638 unsigned int reloc_type
,
3642 #ifdef HAVE_TARGET_32_BIG
3645 Layout::layout_eh_frame
<32, true>(Sized_relobj
<32, true>* object
,
3646 const unsigned char* symbols
,
3648 const unsigned char* symbol_names
,
3649 off_t symbol_names_size
,
3651 const elfcpp::Shdr
<32, true>& shdr
,
3652 unsigned int reloc_shndx
,
3653 unsigned int reloc_type
,
3657 #ifdef HAVE_TARGET_64_LITTLE
3660 Layout::layout_eh_frame
<64, false>(Sized_relobj
<64, false>* object
,
3661 const unsigned char* symbols
,
3663 const unsigned char* symbol_names
,
3664 off_t symbol_names_size
,
3666 const elfcpp::Shdr
<64, false>& shdr
,
3667 unsigned int reloc_shndx
,
3668 unsigned int reloc_type
,
3672 #ifdef HAVE_TARGET_64_BIG
3675 Layout::layout_eh_frame
<64, true>(Sized_relobj
<64, true>* object
,
3676 const unsigned char* symbols
,
3678 const unsigned char* symbol_names
,
3679 off_t symbol_names_size
,
3681 const elfcpp::Shdr
<64, true>& shdr
,
3682 unsigned int reloc_shndx
,
3683 unsigned int reloc_type
,
3687 } // End namespace gold.