1 // layout.cc -- lay out output file sections for gold
3 // Copyright 2006, 2007, 2008 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.
30 #include "parameters.h"
33 #include "script-sections.h"
38 #include "compressed_output.h"
45 // Layout_task_runner methods.
47 // Lay out the sections. This is called after all the input objects
51 Layout_task_runner::run(Workqueue
* workqueue
, const Task
* task
)
53 off_t file_size
= this->layout_
->finalize(this->input_objects_
,
57 // Now we know the final size of the output file and we know where
58 // each piece of information goes.
59 Output_file
* of
= new Output_file(parameters
->output_file_name());
60 if (this->options_
.oformat() != General_options::OBJECT_FORMAT_ELF
)
61 of
->set_is_temporary();
64 // Queue up the final set of tasks.
65 gold::queue_final_tasks(this->options_
, this->input_objects_
,
66 this->symtab_
, this->layout_
, workqueue
, of
);
71 Layout::Layout(const General_options
& options
, Script_options
* script_options
)
72 : options_(options
), script_options_(script_options
), namepool_(),
73 sympool_(), dynpool_(), signatures_(),
74 section_name_map_(), segment_list_(), section_list_(),
75 unattached_section_list_(), special_output_list_(),
76 section_headers_(NULL
), tls_segment_(NULL
), symtab_section_(NULL
),
77 dynsym_section_(NULL
), dynamic_section_(NULL
), dynamic_data_(NULL
),
78 eh_frame_section_(NULL
), group_signatures_(), output_file_size_(-1),
79 input_requires_executable_stack_(false),
80 input_with_gnu_stack_note_(false),
81 input_without_gnu_stack_note_(false),
82 has_static_tls_(false),
83 any_postprocessing_sections_(false)
85 // Make space for more than enough segments for a typical file.
86 // This is just for efficiency--it's OK if we wind up needing more.
87 this->segment_list_
.reserve(12);
89 // We expect two unattached Output_data objects: the file header and
90 // the segment headers.
91 this->special_output_list_
.reserve(2);
94 // Hash a key we use to look up an output section mapping.
97 Layout::Hash_key::operator()(const Layout::Key
& k
) const
99 return k
.first
+ k
.second
.first
+ k
.second
.second
;
102 // Return whether PREFIX is a prefix of STR.
105 is_prefix_of(const char* prefix
, const char* str
)
107 return strncmp(prefix
, str
, strlen(prefix
)) == 0;
110 // Returns whether the given section is in the list of
111 // debug-sections-used-by-some-version-of-gdb. Currently,
112 // we've checked versions of gdb up to and including 6.7.1.
114 static const char* gdb_sections
[] =
116 // ".debug_aranges", // not used by gdb as of 6.7.1
122 // ".debug_pubnames", // not used by gdb as of 6.7.1
128 is_gdb_debug_section(const char* str
)
130 // We can do this faster: binary search or a hashtable. But why bother?
131 for (size_t i
= 0; i
< sizeof(gdb_sections
)/sizeof(*gdb_sections
); ++i
)
132 if (strcmp(str
, gdb_sections
[i
]) == 0)
137 // Whether to include this section in the link.
139 template<int size
, bool big_endian
>
141 Layout::include_section(Sized_relobj
<size
, big_endian
>*, const char* name
,
142 const elfcpp::Shdr
<size
, big_endian
>& shdr
)
144 switch (shdr
.get_sh_type())
146 case elfcpp::SHT_NULL
:
147 case elfcpp::SHT_SYMTAB
:
148 case elfcpp::SHT_DYNSYM
:
149 case elfcpp::SHT_STRTAB
:
150 case elfcpp::SHT_HASH
:
151 case elfcpp::SHT_DYNAMIC
:
152 case elfcpp::SHT_SYMTAB_SHNDX
:
155 case elfcpp::SHT_RELA
:
156 case elfcpp::SHT_REL
:
157 case elfcpp::SHT_GROUP
:
158 // For a relocatable link these should be handled elsewhere.
159 gold_assert(!parameters
->output_is_object());
162 case elfcpp::SHT_PROGBITS
:
163 if (parameters
->strip_debug()
164 && (shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) == 0)
166 // Debugging sections can only be recognized by name.
167 if (is_prefix_of(".debug", name
)
168 || is_prefix_of(".gnu.linkonce.wi.", name
)
169 || is_prefix_of(".line", name
)
170 || is_prefix_of(".stab", name
))
173 if (parameters
->strip_debug_gdb()
174 && (shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) == 0)
176 // Debugging sections can only be recognized by name.
177 if (is_prefix_of(".debug", name
)
178 && !is_gdb_debug_section(name
))
188 // Return an output section named NAME, or NULL if there is none.
191 Layout::find_output_section(const char* name
) const
193 for (Section_list::const_iterator p
= this->section_list_
.begin();
194 p
!= this->section_list_
.end();
196 if (strcmp((*p
)->name(), name
) == 0)
201 // Return an output segment of type TYPE, with segment flags SET set
202 // and segment flags CLEAR clear. Return NULL if there is none.
205 Layout::find_output_segment(elfcpp::PT type
, elfcpp::Elf_Word set
,
206 elfcpp::Elf_Word clear
) const
208 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
209 p
!= this->segment_list_
.end();
211 if (static_cast<elfcpp::PT
>((*p
)->type()) == type
212 && ((*p
)->flags() & set
) == set
213 && ((*p
)->flags() & clear
) == 0)
218 // Return the output section to use for section NAME with type TYPE
219 // and section flags FLAGS. NAME must be canonicalized in the string
220 // pool, and NAME_KEY is the key.
223 Layout::get_output_section(const char* name
, Stringpool::Key name_key
,
224 elfcpp::Elf_Word type
, elfcpp::Elf_Xword flags
)
226 const Key
key(name_key
, std::make_pair(type
, flags
));
227 const std::pair
<Key
, Output_section
*> v(key
, NULL
);
228 std::pair
<Section_name_map::iterator
, bool> ins(
229 this->section_name_map_
.insert(v
));
232 return ins
.first
->second
;
235 // This is the first time we've seen this name/type/flags
237 Output_section
* os
= this->make_output_section(name
, type
, flags
);
238 ins
.first
->second
= os
;
243 // Pick the output section to use for section NAME, in input file
244 // RELOBJ, with type TYPE and flags FLAGS. RELOBJ may be NULL for a
245 // linker created section. ADJUST_NAME is true if we should apply the
246 // standard name mappings in Layout::output_section_name. This will
247 // return NULL if the input section should be discarded.
250 Layout::choose_output_section(const Relobj
* relobj
, const char* name
,
251 elfcpp::Elf_Word type
, elfcpp::Elf_Xword flags
,
254 // We should ignore some flags. FIXME: This will need some
255 // adjustment for ld -r.
256 flags
&= ~ (elfcpp::SHF_INFO_LINK
257 | elfcpp::SHF_LINK_ORDER
260 | elfcpp::SHF_STRINGS
);
262 if (this->script_options_
->saw_sections_clause())
264 // We are using a SECTIONS clause, so the output section is
265 // chosen based only on the name.
267 Script_sections
* ss
= this->script_options_
->script_sections();
268 const char* file_name
= relobj
== NULL
? NULL
: relobj
->name().c_str();
269 Output_section
** output_section_slot
;
270 name
= ss
->output_section_name(file_name
, name
, &output_section_slot
);
273 // The SECTIONS clause says to discard this input section.
277 // If this is an orphan section--one not mentioned in the linker
278 // script--then OUTPUT_SECTION_SLOT will be NULL, and we do the
279 // default processing below.
281 if (output_section_slot
!= NULL
)
283 if (*output_section_slot
!= NULL
)
284 return *output_section_slot
;
286 // We don't put sections found in the linker script into
287 // SECTION_NAME_MAP_. That keeps us from getting confused
288 // if an orphan section is mapped to a section with the same
289 // name as one in the linker script.
291 name
= this->namepool_
.add(name
, false, NULL
);
293 Output_section
* os
= this->make_output_section(name
, type
, flags
);
294 os
->set_found_in_sections_clause();
295 *output_section_slot
= os
;
300 // FIXME: Handle SHF_OS_NONCONFORMING somewhere.
302 // Turn NAME from the name of the input section into the name of the
305 size_t len
= strlen(name
);
306 if (adjust_name
&& !parameters
->output_is_object())
307 name
= Layout::output_section_name(name
, &len
);
309 Stringpool::Key name_key
;
310 name
= this->namepool_
.add_with_length(name
, len
, true, &name_key
);
312 // Find or make the output section. The output section is selected
313 // based on the section name, type, and flags.
314 return this->get_output_section(name
, name_key
, type
, flags
);
317 // Return the output section to use for input section SHNDX, with name
318 // NAME, with header HEADER, from object OBJECT. RELOC_SHNDX is the
319 // index of a relocation section which applies to this section, or 0
320 // if none, or -1U if more than one. RELOC_TYPE is the type of the
321 // relocation section if there is one. Set *OFF to the offset of this
322 // input section without the output section. Return NULL if the
323 // section should be discarded. Set *OFF to -1 if the section
324 // contents should not be written directly to the output file, but
325 // will instead receive special handling.
327 template<int size
, bool big_endian
>
329 Layout::layout(Sized_relobj
<size
, big_endian
>* object
, unsigned int shndx
,
330 const char* name
, const elfcpp::Shdr
<size
, big_endian
>& shdr
,
331 unsigned int reloc_shndx
, unsigned int, off_t
* off
)
333 if (!this->include_section(object
, name
, shdr
))
338 // In a relocatable link a grouped section must not be combined with
339 // any other sections.
340 if (parameters
->output_is_object()
341 && (shdr
.get_sh_flags() & elfcpp::SHF_GROUP
) != 0)
343 name
= this->namepool_
.add(name
, true, NULL
);
344 os
= this->make_output_section(name
, shdr
.get_sh_type(),
345 shdr
.get_sh_flags());
349 os
= this->choose_output_section(object
, name
, shdr
.get_sh_type(),
350 shdr
.get_sh_flags(), true);
355 // FIXME: Handle SHF_LINK_ORDER somewhere.
357 *off
= os
->add_input_section(object
, shndx
, name
, shdr
, reloc_shndx
,
358 this->script_options_
->saw_sections_clause());
363 // Handle a relocation section when doing a relocatable link.
365 template<int size
, bool big_endian
>
367 Layout::layout_reloc(Sized_relobj
<size
, big_endian
>* object
,
369 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
370 Output_section
* data_section
,
371 Relocatable_relocs
* rr
)
373 gold_assert(parameters
->output_is_object());
375 int sh_type
= shdr
.get_sh_type();
378 if (sh_type
== elfcpp::SHT_REL
)
380 else if (sh_type
== elfcpp::SHT_RELA
)
384 name
+= data_section
->name();
386 Output_section
* os
= this->choose_output_section(object
, name
.c_str(),
391 os
->set_should_link_to_symtab();
392 os
->set_info_section(data_section
);
394 Output_section_data
* posd
;
395 if (sh_type
== elfcpp::SHT_REL
)
397 os
->set_entsize(elfcpp::Elf_sizes
<size
>::rel_size
);
398 posd
= new Output_relocatable_relocs
<elfcpp::SHT_REL
,
402 else if (sh_type
== elfcpp::SHT_RELA
)
404 os
->set_entsize(elfcpp::Elf_sizes
<size
>::rela_size
);
405 posd
= new Output_relocatable_relocs
<elfcpp::SHT_RELA
,
412 os
->add_output_section_data(posd
);
413 rr
->set_output_data(posd
);
418 // Handle a group section when doing a relocatable link.
420 template<int size
, bool big_endian
>
422 Layout::layout_group(Symbol_table
* symtab
,
423 Sized_relobj
<size
, big_endian
>* object
,
425 const char* group_section_name
,
426 const char* signature
,
427 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
428 const elfcpp::Elf_Word
* contents
)
430 gold_assert(parameters
->output_is_object());
431 gold_assert(shdr
.get_sh_type() == elfcpp::SHT_GROUP
);
432 group_section_name
= this->namepool_
.add(group_section_name
, true, NULL
);
433 Output_section
* os
= this->make_output_section(group_section_name
,
435 shdr
.get_sh_flags());
437 // We need to find a symbol with the signature in the symbol table.
438 // If we don't find one now, we need to look again later.
439 Symbol
* sym
= symtab
->lookup(signature
, NULL
);
441 os
->set_info_symndx(sym
);
444 // We will wind up using a symbol whose name is the signature.
445 // So just put the signature in the symbol name pool to save it.
446 signature
= symtab
->canonicalize_name(signature
);
447 this->group_signatures_
.push_back(Group_signature(os
, signature
));
450 os
->set_should_link_to_symtab();
453 section_size_type entry_count
=
454 convert_to_section_size_type(shdr
.get_sh_size() / 4);
455 Output_section_data
* posd
=
456 new Output_data_group
<size
, big_endian
>(object
, entry_count
, contents
);
457 os
->add_output_section_data(posd
);
460 // Special GNU handling of sections name .eh_frame. They will
461 // normally hold exception frame data as defined by the C++ ABI
462 // (http://codesourcery.com/cxx-abi/).
464 template<int size
, bool big_endian
>
466 Layout::layout_eh_frame(Sized_relobj
<size
, big_endian
>* object
,
467 const unsigned char* symbols
,
469 const unsigned char* symbol_names
,
470 off_t symbol_names_size
,
472 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
473 unsigned int reloc_shndx
, unsigned int reloc_type
,
476 gold_assert(shdr
.get_sh_type() == elfcpp::SHT_PROGBITS
);
477 gold_assert(shdr
.get_sh_flags() == elfcpp::SHF_ALLOC
);
479 const char* const name
= ".eh_frame";
480 Output_section
* os
= this->choose_output_section(object
,
482 elfcpp::SHT_PROGBITS
,
488 if (this->eh_frame_section_
== NULL
)
490 this->eh_frame_section_
= os
;
491 this->eh_frame_data_
= new Eh_frame();
492 os
->add_output_section_data(this->eh_frame_data_
);
494 if (this->options_
.eh_frame_hdr())
496 Output_section
* hdr_os
=
497 this->choose_output_section(NULL
,
499 elfcpp::SHT_PROGBITS
,
505 Eh_frame_hdr
* hdr_posd
= new Eh_frame_hdr(os
,
506 this->eh_frame_data_
);
507 hdr_os
->add_output_section_data(hdr_posd
);
509 hdr_os
->set_after_input_sections();
511 if (!this->script_options_
->saw_phdrs_clause())
513 Output_segment
* hdr_oseg
;
514 hdr_oseg
= this->make_output_segment(elfcpp::PT_GNU_EH_FRAME
,
516 hdr_oseg
->add_output_section(hdr_os
, elfcpp::PF_R
);
519 this->eh_frame_data_
->set_eh_frame_hdr(hdr_posd
);
524 gold_assert(this->eh_frame_section_
== os
);
526 if (this->eh_frame_data_
->add_ehframe_input_section(object
,
537 // We couldn't handle this .eh_frame section for some reason.
538 // Add it as a normal section.
539 bool saw_sections_clause
= this->script_options_
->saw_sections_clause();
540 *off
= os
->add_input_section(object
, shndx
, name
, shdr
, reloc_shndx
,
541 saw_sections_clause
);
547 // Add POSD to an output section using NAME, TYPE, and FLAGS.
550 Layout::add_output_section_data(const char* name
, elfcpp::Elf_Word type
,
551 elfcpp::Elf_Xword flags
,
552 Output_section_data
* posd
)
554 Output_section
* os
= this->choose_output_section(NULL
, name
, type
, flags
,
557 os
->add_output_section_data(posd
);
560 // Map section flags to segment flags.
563 Layout::section_flags_to_segment(elfcpp::Elf_Xword flags
)
565 elfcpp::Elf_Word ret
= elfcpp::PF_R
;
566 if ((flags
& elfcpp::SHF_WRITE
) != 0)
568 if ((flags
& elfcpp::SHF_EXECINSTR
) != 0)
573 // Sometimes we compress sections. This is typically done for
574 // sections that are not part of normal program execution (such as
575 // .debug_* sections), and where the readers of these sections know
576 // how to deal with compressed sections. (To make it easier for them,
577 // we will rename the ouput section in such cases from .foo to
578 // .foo.zlib.nnnn, where nnnn is the uncompressed size.) This routine
579 // doesn't say for certain whether we'll compress -- it depends on
580 // commandline options as well -- just whether this section is a
581 // candidate for compression.
584 is_compressible_debug_section(const char* secname
)
586 return (strncmp(secname
, ".debug", sizeof(".debug") - 1) == 0);
589 // Make a new Output_section, and attach it to segments as
593 Layout::make_output_section(const char* name
, elfcpp::Elf_Word type
,
594 elfcpp::Elf_Xword flags
)
597 if ((flags
& elfcpp::SHF_ALLOC
) == 0
598 && this->options_
.compress_debug_sections()
599 && is_compressible_debug_section(name
))
600 os
= new Output_compressed_section(&this->options_
, name
, type
, flags
);
602 os
= new Output_section(name
, type
, flags
);
604 this->section_list_
.push_back(os
);
606 if ((flags
& elfcpp::SHF_ALLOC
) == 0)
607 this->unattached_section_list_
.push_back(os
);
610 if (parameters
->output_is_object())
613 // If we have a SECTIONS clause, we can't handle the attachment
614 // to segments until after we've seen all the sections.
615 if (this->script_options_
->saw_sections_clause())
618 gold_assert(!this->script_options_
->saw_phdrs_clause());
620 // This output section goes into a PT_LOAD segment.
622 elfcpp::Elf_Word seg_flags
= Layout::section_flags_to_segment(flags
);
624 // In general the only thing we really care about for PT_LOAD
625 // segments is whether or not they are writable, so that is how
626 // we search for them. People who need segments sorted on some
627 // other basis will have to use a linker script.
629 Segment_list::const_iterator p
;
630 for (p
= this->segment_list_
.begin();
631 p
!= this->segment_list_
.end();
634 if ((*p
)->type() == elfcpp::PT_LOAD
635 && ((*p
)->flags() & elfcpp::PF_W
) == (seg_flags
& elfcpp::PF_W
))
637 // If -Tbss was specified, we need to separate the data
639 if (this->options_
.user_set_Tbss())
641 if ((type
== elfcpp::SHT_NOBITS
)
642 == (*p
)->has_any_data_sections())
646 (*p
)->add_output_section(os
, seg_flags
);
651 if (p
== this->segment_list_
.end())
653 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_LOAD
,
655 oseg
->add_output_section(os
, seg_flags
);
658 // If we see a loadable SHT_NOTE section, we create a PT_NOTE
660 if (type
== elfcpp::SHT_NOTE
)
662 // See if we already have an equivalent PT_NOTE segment.
663 for (p
= this->segment_list_
.begin();
664 p
!= segment_list_
.end();
667 if ((*p
)->type() == elfcpp::PT_NOTE
668 && (((*p
)->flags() & elfcpp::PF_W
)
669 == (seg_flags
& elfcpp::PF_W
)))
671 (*p
)->add_output_section(os
, seg_flags
);
676 if (p
== this->segment_list_
.end())
678 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_NOTE
,
680 oseg
->add_output_section(os
, seg_flags
);
684 // If we see a loadable SHF_TLS section, we create a PT_TLS
685 // segment. There can only be one such segment.
686 if ((flags
& elfcpp::SHF_TLS
) != 0)
688 if (this->tls_segment_
== NULL
)
689 this->tls_segment_
= this->make_output_segment(elfcpp::PT_TLS
,
691 this->tls_segment_
->add_output_section(os
, seg_flags
);
698 // Return the number of segments we expect to see.
701 Layout::expected_segment_count() const
703 size_t ret
= this->segment_list_
.size();
705 // If we didn't see a SECTIONS clause in a linker script, we should
706 // already have the complete list of segments. Otherwise we ask the
707 // SECTIONS clause how many segments it expects, and add in the ones
708 // we already have (PT_GNU_STACK, PT_GNU_EH_FRAME, etc.)
710 if (!this->script_options_
->saw_sections_clause())
714 const Script_sections
* ss
= this->script_options_
->script_sections();
715 return ret
+ ss
->expected_segment_count(this);
719 // Handle the .note.GNU-stack section at layout time. SEEN_GNU_STACK
720 // is whether we saw a .note.GNU-stack section in the object file.
721 // GNU_STACK_FLAGS is the section flags. The flags give the
722 // protection required for stack memory. We record this in an
723 // executable as a PT_GNU_STACK segment. If an object file does not
724 // have a .note.GNU-stack segment, we must assume that it is an old
725 // object. On some targets that will force an executable stack.
728 Layout::layout_gnu_stack(bool seen_gnu_stack
, uint64_t gnu_stack_flags
)
731 this->input_without_gnu_stack_note_
= true;
734 this->input_with_gnu_stack_note_
= true;
735 if ((gnu_stack_flags
& elfcpp::SHF_EXECINSTR
) != 0)
736 this->input_requires_executable_stack_
= true;
740 // Create the dynamic sections which are needed before we read the
744 Layout::create_initial_dynamic_sections(Symbol_table
* symtab
)
746 if (parameters
->doing_static_link())
749 this->dynamic_section_
= this->choose_output_section(NULL
, ".dynamic",
752 | elfcpp::SHF_WRITE
),
755 symtab
->define_in_output_data("_DYNAMIC", NULL
, this->dynamic_section_
, 0, 0,
756 elfcpp::STT_OBJECT
, elfcpp::STB_LOCAL
,
757 elfcpp::STV_HIDDEN
, 0, false, false);
759 this->dynamic_data_
= new Output_data_dynamic(&this->dynpool_
);
761 this->dynamic_section_
->add_output_section_data(this->dynamic_data_
);
764 // For each output section whose name can be represented as C symbol,
765 // define __start and __stop symbols for the section. This is a GNU
769 Layout::define_section_symbols(Symbol_table
* symtab
)
771 for (Section_list::const_iterator p
= this->section_list_
.begin();
772 p
!= this->section_list_
.end();
775 const char* const name
= (*p
)->name();
776 if (name
[strspn(name
,
778 "ABCDEFGHIJKLMNOPWRSTUVWXYZ"
779 "abcdefghijklmnopqrstuvwxyz"
783 const std::string
name_string(name
);
784 const std::string
start_name("__start_" + name_string
);
785 const std::string
stop_name("__stop_" + name_string
);
787 symtab
->define_in_output_data(start_name
.c_str(),
796 false, // offset_is_from_end
797 true); // only_if_ref
799 symtab
->define_in_output_data(stop_name
.c_str(),
808 true, // offset_is_from_end
809 true); // only_if_ref
814 // Define symbols for group signatures.
817 Layout::define_group_signatures(Symbol_table
* symtab
)
819 for (Group_signatures::iterator p
= this->group_signatures_
.begin();
820 p
!= this->group_signatures_
.end();
823 Symbol
* sym
= symtab
->lookup(p
->signature
, NULL
);
825 p
->section
->set_info_symndx(sym
);
828 // Force the name of the group section to the group
829 // signature, and use the group's section symbol as the
831 if (strcmp(p
->section
->name(), p
->signature
) != 0)
833 const char* name
= this->namepool_
.add(p
->signature
,
835 p
->section
->set_name(name
);
837 p
->section
->set_needs_symtab_index();
838 p
->section
->set_info_section_symndx(p
->section
);
842 this->group_signatures_
.clear();
845 // Find the first read-only PT_LOAD segment, creating one if
849 Layout::find_first_load_seg()
851 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
852 p
!= this->segment_list_
.end();
855 if ((*p
)->type() == elfcpp::PT_LOAD
856 && ((*p
)->flags() & elfcpp::PF_R
) != 0
857 && ((*p
)->flags() & elfcpp::PF_W
) == 0)
861 gold_assert(!this->script_options_
->saw_phdrs_clause());
863 Output_segment
* load_seg
= this->make_output_segment(elfcpp::PT_LOAD
,
868 // Finalize the layout. When this is called, we have created all the
869 // output sections and all the output segments which are based on
870 // input sections. We have several things to do, and we have to do
871 // them in the right order, so that we get the right results correctly
874 // 1) Finalize the list of output segments and create the segment
877 // 2) Finalize the dynamic symbol table and associated sections.
879 // 3) Determine the final file offset of all the output segments.
881 // 4) Determine the final file offset of all the SHF_ALLOC output
884 // 5) Create the symbol table sections and the section name table
887 // 6) Finalize the symbol table: set symbol values to their final
888 // value and make a final determination of which symbols are going
889 // into the output symbol table.
891 // 7) Create the section table header.
893 // 8) Determine the final file offset of all the output sections which
894 // are not SHF_ALLOC, including the section table header.
896 // 9) Finalize the ELF file header.
898 // This function returns the size of the output file.
901 Layout::finalize(const Input_objects
* input_objects
, Symbol_table
* symtab
,
904 Target
* const target
= parameters
->target();
906 target
->finalize_sections(this);
908 this->count_local_symbols(task
, input_objects
);
910 this->create_gold_note();
911 this->create_executable_stack_info(target
);
913 Output_segment
* phdr_seg
= NULL
;
914 if (!parameters
->output_is_object() && !parameters
->doing_static_link())
916 // There was a dynamic object in the link. We need to create
917 // some information for the dynamic linker.
919 // Create the PT_PHDR segment which will hold the program
921 if (!this->script_options_
->saw_phdrs_clause())
922 phdr_seg
= this->make_output_segment(elfcpp::PT_PHDR
, elfcpp::PF_R
);
924 // Create the dynamic symbol table, including the hash table.
925 Output_section
* dynstr
;
926 std::vector
<Symbol
*> dynamic_symbols
;
927 unsigned int local_dynamic_count
;
928 Versions
versions(*this->script_options()->version_script_info(),
930 this->create_dynamic_symtab(input_objects
, symtab
, &dynstr
,
931 &local_dynamic_count
, &dynamic_symbols
,
934 // Create the .interp section to hold the name of the
935 // interpreter, and put it in a PT_INTERP segment.
936 if (!parameters
->output_is_shared())
937 this->create_interp(target
);
939 // Finish the .dynamic section to hold the dynamic data, and put
940 // it in a PT_DYNAMIC segment.
941 this->finish_dynamic_section(input_objects
, symtab
);
943 // We should have added everything we need to the dynamic string
945 this->dynpool_
.set_string_offsets();
947 // Create the version sections. We can't do this until the
948 // dynamic string table is complete.
949 this->create_version_sections(&versions
, symtab
, local_dynamic_count
,
950 dynamic_symbols
, dynstr
);
953 // If there is a SECTIONS clause, put all the input sections into
954 // the required order.
955 Output_segment
* load_seg
;
956 if (this->script_options_
->saw_sections_clause())
957 load_seg
= this->set_section_addresses_from_script(symtab
);
958 else if (parameters
->output_is_object())
961 load_seg
= this->find_first_load_seg();
963 if (this->options_
.oformat() != General_options::OBJECT_FORMAT_ELF
)
966 gold_assert(phdr_seg
== NULL
|| load_seg
!= NULL
);
968 // Lay out the segment headers.
969 Output_segment_headers
* segment_headers
;
970 if (parameters
->output_is_object())
971 segment_headers
= NULL
;
974 segment_headers
= new Output_segment_headers(this->segment_list_
);
975 if (load_seg
!= NULL
)
976 load_seg
->add_initial_output_data(segment_headers
);
977 if (phdr_seg
!= NULL
)
978 phdr_seg
->add_initial_output_data(segment_headers
);
981 // Lay out the file header.
982 Output_file_header
* file_header
;
983 file_header
= new Output_file_header(target
, symtab
, segment_headers
,
984 this->options_
.entry());
985 if (load_seg
!= NULL
)
986 load_seg
->add_initial_output_data(file_header
);
988 this->special_output_list_
.push_back(file_header
);
989 if (segment_headers
!= NULL
)
990 this->special_output_list_
.push_back(segment_headers
);
992 if (this->script_options_
->saw_phdrs_clause()
993 && !parameters
->output_is_object())
995 // Support use of FILEHDRS and PHDRS attachments in a PHDRS
996 // clause in a linker script.
997 Script_sections
* ss
= this->script_options_
->script_sections();
998 ss
->put_headers_in_phdrs(file_header
, segment_headers
);
1001 // We set the output section indexes in set_segment_offsets and
1002 // set_section_indexes.
1003 unsigned int shndx
= 1;
1005 // Set the file offsets of all the segments, and all the sections
1008 if (!parameters
->output_is_object())
1009 off
= this->set_segment_offsets(target
, load_seg
, &shndx
);
1011 off
= this->set_relocatable_section_offsets(file_header
, &shndx
);
1013 // Set the file offsets of all the non-data sections we've seen so
1014 // far which don't have to wait for the input sections. We need
1015 // this in order to finalize local symbols in non-allocated
1017 off
= this->set_section_offsets(off
, BEFORE_INPUT_SECTIONS_PASS
);
1019 // Create the symbol table sections.
1020 this->create_symtab_sections(input_objects
, symtab
, &off
);
1021 if (!parameters
->doing_static_link())
1022 this->assign_local_dynsym_offsets(input_objects
);
1024 // Process any symbol assignments from a linker script. This must
1025 // be called after the symbol table has been finalized.
1026 this->script_options_
->finalize_symbols(symtab
, this);
1028 // Create the .shstrtab section.
1029 Output_section
* shstrtab_section
= this->create_shstrtab();
1031 // Set the file offsets of the rest of the non-data sections which
1032 // don't have to wait for the input sections.
1033 off
= this->set_section_offsets(off
, BEFORE_INPUT_SECTIONS_PASS
);
1035 // Now that all sections have been created, set the section indexes.
1036 shndx
= this->set_section_indexes(shndx
);
1038 // Create the section table header.
1039 this->create_shdrs(&off
);
1041 // If there are no sections which require postprocessing, we can
1042 // handle the section names now, and avoid a resize later.
1043 if (!this->any_postprocessing_sections_
)
1044 off
= this->set_section_offsets(off
,
1045 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
);
1047 file_header
->set_section_info(this->section_headers_
, shstrtab_section
);
1049 // Now we know exactly where everything goes in the output file
1050 // (except for non-allocated sections which require postprocessing).
1051 Output_data::layout_complete();
1053 this->output_file_size_
= off
;
1058 // Create a .note section for an executable or shared library. This
1059 // records the version of gold used to create the binary.
1062 Layout::create_gold_note()
1064 if (parameters
->output_is_object())
1067 // Authorities all agree that the values in a .note field should
1068 // be aligned on 4-byte boundaries for 32-bit binaries. However,
1069 // they differ on what the alignment is for 64-bit binaries.
1070 // The GABI says unambiguously they take 8-byte alignment:
1071 // http://sco.com/developers/gabi/latest/ch5.pheader.html#note_section
1072 // Other documentation says alignment should always be 4 bytes:
1073 // http://www.netbsd.org/docs/kernel/elf-notes.html#note-format
1074 // GNU ld and GNU readelf both support the latter (at least as of
1075 // version 2.16.91), and glibc always generates the latter for
1076 // .note.ABI-tag (as of version 1.6), so that's the one we go with
1078 #ifdef GABI_FORMAT_FOR_DOTNOTE_SECTION // This is not defined by default.
1079 const int size
= parameters
->get_size();
1081 const int size
= 32;
1084 // The contents of the .note section.
1085 const char* name
= "GNU";
1086 std::string
desc(std::string("gold ") + gold::get_version_string());
1087 size_t namesz
= strlen(name
) + 1;
1088 size_t aligned_namesz
= align_address(namesz
, size
/ 8);
1089 size_t descsz
= desc
.length() + 1;
1090 size_t aligned_descsz
= align_address(descsz
, size
/ 8);
1091 const int note_type
= 4;
1093 size_t notesz
= 3 * (size
/ 8) + aligned_namesz
+ aligned_descsz
;
1095 unsigned char buffer
[128];
1096 gold_assert(sizeof buffer
>= notesz
);
1097 memset(buffer
, 0, notesz
);
1099 bool is_big_endian
= parameters
->is_big_endian();
1105 elfcpp::Swap
<32, false>::writeval(buffer
, namesz
);
1106 elfcpp::Swap
<32, false>::writeval(buffer
+ 4, descsz
);
1107 elfcpp::Swap
<32, false>::writeval(buffer
+ 8, note_type
);
1111 elfcpp::Swap
<32, true>::writeval(buffer
, namesz
);
1112 elfcpp::Swap
<32, true>::writeval(buffer
+ 4, descsz
);
1113 elfcpp::Swap
<32, true>::writeval(buffer
+ 8, note_type
);
1116 else if (size
== 64)
1120 elfcpp::Swap
<64, false>::writeval(buffer
, namesz
);
1121 elfcpp::Swap
<64, false>::writeval(buffer
+ 8, descsz
);
1122 elfcpp::Swap
<64, false>::writeval(buffer
+ 16, note_type
);
1126 elfcpp::Swap
<64, true>::writeval(buffer
, namesz
);
1127 elfcpp::Swap
<64, true>::writeval(buffer
+ 8, descsz
);
1128 elfcpp::Swap
<64, true>::writeval(buffer
+ 16, note_type
);
1134 memcpy(buffer
+ 3 * (size
/ 8), name
, namesz
);
1135 memcpy(buffer
+ 3 * (size
/ 8) + aligned_namesz
, desc
.data(), descsz
);
1137 const char* note_name
= this->namepool_
.add(".note", false, NULL
);
1138 Output_section
* os
= this->make_output_section(note_name
,
1141 Output_section_data
* posd
= new Output_data_const(buffer
, notesz
,
1143 os
->add_output_section_data(posd
);
1146 // Record whether the stack should be executable. This can be set
1147 // from the command line using the -z execstack or -z noexecstack
1148 // options. Otherwise, if any input file has a .note.GNU-stack
1149 // section with the SHF_EXECINSTR flag set, the stack should be
1150 // executable. Otherwise, if at least one input file a
1151 // .note.GNU-stack section, and some input file has no .note.GNU-stack
1152 // section, we use the target default for whether the stack should be
1153 // executable. Otherwise, we don't generate a stack note. When
1154 // generating a object file, we create a .note.GNU-stack section with
1155 // the appropriate marking. When generating an executable or shared
1156 // library, we create a PT_GNU_STACK segment.
1159 Layout::create_executable_stack_info(const Target
* target
)
1161 bool is_stack_executable
;
1162 if (this->options_
.is_execstack_set())
1163 is_stack_executable
= this->options_
.is_stack_executable();
1164 else if (!this->input_with_gnu_stack_note_
)
1168 if (this->input_requires_executable_stack_
)
1169 is_stack_executable
= true;
1170 else if (this->input_without_gnu_stack_note_
)
1171 is_stack_executable
= target
->is_default_stack_executable();
1173 is_stack_executable
= false;
1176 if (parameters
->output_is_object())
1178 const char* name
= this->namepool_
.add(".note.GNU-stack", false, NULL
);
1179 elfcpp::Elf_Xword flags
= 0;
1180 if (is_stack_executable
)
1181 flags
|= elfcpp::SHF_EXECINSTR
;
1182 this->make_output_section(name
, elfcpp::SHT_PROGBITS
, flags
);
1186 if (this->script_options_
->saw_phdrs_clause())
1188 int flags
= elfcpp::PF_R
| elfcpp::PF_W
;
1189 if (is_stack_executable
)
1190 flags
|= elfcpp::PF_X
;
1191 this->make_output_segment(elfcpp::PT_GNU_STACK
, flags
);
1195 // Return whether SEG1 should be before SEG2 in the output file. This
1196 // is based entirely on the segment type and flags. When this is
1197 // called the segment addresses has normally not yet been set.
1200 Layout::segment_precedes(const Output_segment
* seg1
,
1201 const Output_segment
* seg2
)
1203 elfcpp::Elf_Word type1
= seg1
->type();
1204 elfcpp::Elf_Word type2
= seg2
->type();
1206 // The single PT_PHDR segment is required to precede any loadable
1207 // segment. We simply make it always first.
1208 if (type1
== elfcpp::PT_PHDR
)
1210 gold_assert(type2
!= elfcpp::PT_PHDR
);
1213 if (type2
== elfcpp::PT_PHDR
)
1216 // The single PT_INTERP segment is required to precede any loadable
1217 // segment. We simply make it always second.
1218 if (type1
== elfcpp::PT_INTERP
)
1220 gold_assert(type2
!= elfcpp::PT_INTERP
);
1223 if (type2
== elfcpp::PT_INTERP
)
1226 // We then put PT_LOAD segments before any other segments.
1227 if (type1
== elfcpp::PT_LOAD
&& type2
!= elfcpp::PT_LOAD
)
1229 if (type2
== elfcpp::PT_LOAD
&& type1
!= elfcpp::PT_LOAD
)
1232 // We put the PT_TLS segment last, because that is where the dynamic
1233 // linker expects to find it (this is just for efficiency; other
1234 // positions would also work correctly).
1235 if (type1
== elfcpp::PT_TLS
&& type2
!= elfcpp::PT_TLS
)
1237 if (type2
== elfcpp::PT_TLS
&& type1
!= elfcpp::PT_TLS
)
1240 const elfcpp::Elf_Word flags1
= seg1
->flags();
1241 const elfcpp::Elf_Word flags2
= seg2
->flags();
1243 // The order of non-PT_LOAD segments is unimportant. We simply sort
1244 // by the numeric segment type and flags values. There should not
1245 // be more than one segment with the same type and flags.
1246 if (type1
!= elfcpp::PT_LOAD
)
1249 return type1
< type2
;
1250 gold_assert(flags1
!= flags2
);
1251 return flags1
< flags2
;
1254 // If the addresses are set already, sort by load address.
1255 if (seg1
->are_addresses_set())
1257 if (!seg2
->are_addresses_set())
1260 unsigned int section_count1
= seg1
->output_section_count();
1261 unsigned int section_count2
= seg2
->output_section_count();
1262 if (section_count1
== 0 && section_count2
> 0)
1264 if (section_count1
> 0 && section_count2
== 0)
1267 uint64_t paddr1
= seg1
->first_section_load_address();
1268 uint64_t paddr2
= seg2
->first_section_load_address();
1269 if (paddr1
!= paddr2
)
1270 return paddr1
< paddr2
;
1272 else if (seg2
->are_addresses_set())
1275 // We sort PT_LOAD segments based on the flags. Readonly segments
1276 // come before writable segments. Then writable segments with data
1277 // come before writable segments without data. Then executable
1278 // segments come before non-executable segments. Then the unlikely
1279 // case of a non-readable segment comes before the normal case of a
1280 // readable segment. If there are multiple segments with the same
1281 // type and flags, we require that the address be set, and we sort
1282 // by virtual address and then physical address.
1283 if ((flags1
& elfcpp::PF_W
) != (flags2
& elfcpp::PF_W
))
1284 return (flags1
& elfcpp::PF_W
) == 0;
1285 if ((flags1
& elfcpp::PF_W
) != 0
1286 && seg1
->has_any_data_sections() != seg2
->has_any_data_sections())
1287 return seg1
->has_any_data_sections();
1288 if ((flags1
& elfcpp::PF_X
) != (flags2
& elfcpp::PF_X
))
1289 return (flags1
& elfcpp::PF_X
) != 0;
1290 if ((flags1
& elfcpp::PF_R
) != (flags2
& elfcpp::PF_R
))
1291 return (flags1
& elfcpp::PF_R
) == 0;
1293 // We shouldn't get here--we shouldn't create segments which we
1294 // can't distinguish.
1298 // Set the file offsets of all the segments, and all the sections they
1299 // contain. They have all been created. LOAD_SEG must be be laid out
1300 // first. Return the offset of the data to follow.
1303 Layout::set_segment_offsets(const Target
* target
, Output_segment
* load_seg
,
1304 unsigned int *pshndx
)
1306 // Sort them into the final order.
1307 std::sort(this->segment_list_
.begin(), this->segment_list_
.end(),
1308 Layout::Compare_segments());
1310 // Find the PT_LOAD segments, and set their addresses and offsets
1311 // and their section's addresses and offsets.
1313 if (this->options_
.user_set_Ttext())
1314 addr
= this->options_
.Ttext();
1315 else if (parameters
->output_is_shared())
1318 addr
= target
->default_text_segment_address();
1321 // If LOAD_SEG is NULL, then the file header and segment headers
1322 // will not be loadable. But they still need to be at offset 0 in
1323 // the file. Set their offsets now.
1324 if (load_seg
== NULL
)
1326 for (Data_list::iterator p
= this->special_output_list_
.begin();
1327 p
!= this->special_output_list_
.end();
1330 off
= align_address(off
, (*p
)->addralign());
1331 (*p
)->set_address_and_file_offset(0, off
);
1332 off
+= (*p
)->data_size();
1336 bool was_readonly
= false;
1337 for (Segment_list::iterator p
= this->segment_list_
.begin();
1338 p
!= this->segment_list_
.end();
1341 if ((*p
)->type() == elfcpp::PT_LOAD
)
1343 if (load_seg
!= NULL
&& load_seg
!= *p
)
1347 bool are_addresses_set
= (*p
)->are_addresses_set();
1348 if (are_addresses_set
)
1350 // When it comes to setting file offsets, we care about
1351 // the physical address.
1352 addr
= (*p
)->paddr();
1354 else if (this->options_
.user_set_Tdata()
1355 && ((*p
)->flags() & elfcpp::PF_W
) != 0
1356 && (!this->options_
.user_set_Tbss()
1357 || (*p
)->has_any_data_sections()))
1359 addr
= this->options_
.Tdata();
1360 are_addresses_set
= true;
1362 else if (this->options_
.user_set_Tbss()
1363 && ((*p
)->flags() & elfcpp::PF_W
) != 0
1364 && !(*p
)->has_any_data_sections())
1366 addr
= this->options_
.Tbss();
1367 are_addresses_set
= true;
1370 uint64_t orig_addr
= addr
;
1371 uint64_t orig_off
= off
;
1373 uint64_t aligned_addr
= 0;
1374 uint64_t abi_pagesize
= target
->abi_pagesize();
1376 // FIXME: This should depend on the -n and -N options.
1377 (*p
)->set_minimum_p_align(target
->common_pagesize());
1379 if (are_addresses_set
)
1381 // Adjust the file offset to the same address modulo the
1383 uint64_t unsigned_off
= off
;
1384 uint64_t aligned_off
= ((unsigned_off
& ~(abi_pagesize
- 1))
1385 | (addr
& (abi_pagesize
- 1)));
1386 if (aligned_off
< unsigned_off
)
1387 aligned_off
+= abi_pagesize
;
1392 // If the last segment was readonly, and this one is
1393 // not, then skip the address forward one page,
1394 // maintaining the same position within the page. This
1395 // lets us store both segments overlapping on a single
1396 // page in the file, but the loader will put them on
1397 // different pages in memory.
1399 addr
= align_address(addr
, (*p
)->maximum_alignment());
1400 aligned_addr
= addr
;
1402 if (was_readonly
&& ((*p
)->flags() & elfcpp::PF_W
) != 0)
1404 if ((addr
& (abi_pagesize
- 1)) != 0)
1405 addr
= addr
+ abi_pagesize
;
1408 off
= orig_off
+ ((addr
- orig_addr
) & (abi_pagesize
- 1));
1411 unsigned int shndx_hold
= *pshndx
;
1412 uint64_t new_addr
= (*p
)->set_section_addresses(false, addr
, &off
,
1415 // Now that we know the size of this segment, we may be able
1416 // to save a page in memory, at the cost of wasting some
1417 // file space, by instead aligning to the start of a new
1418 // page. Here we use the real machine page size rather than
1419 // the ABI mandated page size.
1421 if (!are_addresses_set
&& aligned_addr
!= addr
)
1423 uint64_t common_pagesize
= target
->common_pagesize();
1424 uint64_t first_off
= (common_pagesize
1426 & (common_pagesize
- 1)));
1427 uint64_t last_off
= new_addr
& (common_pagesize
- 1);
1430 && ((aligned_addr
& ~ (common_pagesize
- 1))
1431 != (new_addr
& ~ (common_pagesize
- 1)))
1432 && first_off
+ last_off
<= common_pagesize
)
1434 *pshndx
= shndx_hold
;
1435 addr
= align_address(aligned_addr
, common_pagesize
);
1436 addr
= align_address(addr
, (*p
)->maximum_alignment());
1437 off
= orig_off
+ ((addr
- orig_addr
) & (abi_pagesize
- 1));
1438 new_addr
= (*p
)->set_section_addresses(true, addr
, &off
,
1445 if (((*p
)->flags() & elfcpp::PF_W
) == 0)
1446 was_readonly
= true;
1450 // Handle the non-PT_LOAD segments, setting their offsets from their
1451 // section's offsets.
1452 for (Segment_list::iterator p
= this->segment_list_
.begin();
1453 p
!= this->segment_list_
.end();
1456 if ((*p
)->type() != elfcpp::PT_LOAD
)
1460 // Set the TLS offsets for each section in the PT_TLS segment.
1461 if (this->tls_segment_
!= NULL
)
1462 this->tls_segment_
->set_tls_offsets();
1467 // Set the offsets of all the allocated sections when doing a
1468 // relocatable link. This does the same jobs as set_segment_offsets,
1469 // only for a relocatable link.
1472 Layout::set_relocatable_section_offsets(Output_data
* file_header
,
1473 unsigned int *pshndx
)
1477 file_header
->set_address_and_file_offset(0, 0);
1478 off
+= file_header
->data_size();
1480 for (Section_list::iterator p
= this->section_list_
.begin();
1481 p
!= this->section_list_
.end();
1484 // We skip unallocated sections here, except that group sections
1485 // have to come first.
1486 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) == 0
1487 && (*p
)->type() != elfcpp::SHT_GROUP
)
1490 off
= align_address(off
, (*p
)->addralign());
1492 // The linker script might have set the address.
1493 if (!(*p
)->is_address_valid())
1494 (*p
)->set_address(0);
1495 (*p
)->set_file_offset(off
);
1496 (*p
)->finalize_data_size();
1497 off
+= (*p
)->data_size();
1499 (*p
)->set_out_shndx(*pshndx
);
1506 // Set the file offset of all the sections not associated with a
1510 Layout::set_section_offsets(off_t off
, Layout::Section_offset_pass pass
)
1512 for (Section_list::iterator p
= this->unattached_section_list_
.begin();
1513 p
!= this->unattached_section_list_
.end();
1516 // The symtab section is handled in create_symtab_sections.
1517 if (*p
== this->symtab_section_
)
1520 // If we've already set the data size, don't set it again.
1521 if ((*p
)->is_offset_valid() && (*p
)->is_data_size_valid())
1524 if (pass
== BEFORE_INPUT_SECTIONS_PASS
1525 && (*p
)->requires_postprocessing())
1527 (*p
)->create_postprocessing_buffer();
1528 this->any_postprocessing_sections_
= true;
1531 if (pass
== BEFORE_INPUT_SECTIONS_PASS
1532 && (*p
)->after_input_sections())
1534 else if (pass
== POSTPROCESSING_SECTIONS_PASS
1535 && (!(*p
)->after_input_sections()
1536 || (*p
)->type() == elfcpp::SHT_STRTAB
))
1538 else if (pass
== STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
1539 && (!(*p
)->after_input_sections()
1540 || (*p
)->type() != elfcpp::SHT_STRTAB
))
1543 off
= align_address(off
, (*p
)->addralign());
1544 (*p
)->set_file_offset(off
);
1545 (*p
)->finalize_data_size();
1546 off
+= (*p
)->data_size();
1548 // At this point the name must be set.
1549 if (pass
!= STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
)
1550 this->namepool_
.add((*p
)->name(), false, NULL
);
1555 // Set the section indexes of all the sections not associated with a
1559 Layout::set_section_indexes(unsigned int shndx
)
1561 const bool output_is_object
= parameters
->output_is_object();
1562 for (Section_list::iterator p
= this->unattached_section_list_
.begin();
1563 p
!= this->unattached_section_list_
.end();
1566 // In a relocatable link, we already did group sections.
1567 if (output_is_object
1568 && (*p
)->type() == elfcpp::SHT_GROUP
)
1571 (*p
)->set_out_shndx(shndx
);
1577 // Set the section addresses according to the linker script. This is
1578 // only called when we see a SECTIONS clause. This returns the
1579 // program segment which should hold the file header and segment
1580 // headers, if any. It will return NULL if they should not be in a
1584 Layout::set_section_addresses_from_script(Symbol_table
* symtab
)
1586 Script_sections
* ss
= this->script_options_
->script_sections();
1587 gold_assert(ss
->saw_sections_clause());
1589 // Place each orphaned output section in the script.
1590 for (Section_list::iterator p
= this->section_list_
.begin();
1591 p
!= this->section_list_
.end();
1594 if (!(*p
)->found_in_sections_clause())
1595 ss
->place_orphan(*p
);
1598 return this->script_options_
->set_section_addresses(symtab
, this);
1601 // Count the local symbols in the regular symbol table and the dynamic
1602 // symbol table, and build the respective string pools.
1605 Layout::count_local_symbols(const Task
* task
,
1606 const Input_objects
* input_objects
)
1608 // First, figure out an upper bound on the number of symbols we'll
1609 // be inserting into each pool. This helps us create the pools with
1610 // the right size, to avoid unnecessary hashtable resizing.
1611 unsigned int symbol_count
= 0;
1612 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
1613 p
!= input_objects
->relobj_end();
1615 symbol_count
+= (*p
)->local_symbol_count();
1617 // Go from "upper bound" to "estimate." We overcount for two
1618 // reasons: we double-count symbols that occur in more than one
1619 // object file, and we count symbols that are dropped from the
1620 // output. Add it all together and assume we overcount by 100%.
1623 // We assume all symbols will go into both the sympool and dynpool.
1624 this->sympool_
.reserve(symbol_count
);
1625 this->dynpool_
.reserve(symbol_count
);
1627 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
1628 p
!= input_objects
->relobj_end();
1631 Task_lock_obj
<Object
> tlo(task
, *p
);
1632 (*p
)->count_local_symbols(&this->sympool_
, &this->dynpool_
);
1636 // Create the symbol table sections. Here we also set the final
1637 // values of the symbols. At this point all the loadable sections are
1641 Layout::create_symtab_sections(const Input_objects
* input_objects
,
1642 Symbol_table
* symtab
,
1647 if (parameters
->get_size() == 32)
1649 symsize
= elfcpp::Elf_sizes
<32>::sym_size
;
1652 else if (parameters
->get_size() == 64)
1654 symsize
= elfcpp::Elf_sizes
<64>::sym_size
;
1661 off
= align_address(off
, align
);
1662 off_t startoff
= off
;
1664 // Save space for the dummy symbol at the start of the section. We
1665 // never bother to write this out--it will just be left as zero.
1667 unsigned int local_symbol_index
= 1;
1669 // Add STT_SECTION symbols for each Output section which needs one.
1670 for (Section_list::iterator p
= this->section_list_
.begin();
1671 p
!= this->section_list_
.end();
1674 if (!(*p
)->needs_symtab_index())
1675 (*p
)->set_symtab_index(-1U);
1678 (*p
)->set_symtab_index(local_symbol_index
);
1679 ++local_symbol_index
;
1684 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
1685 p
!= input_objects
->relobj_end();
1688 unsigned int index
= (*p
)->finalize_local_symbols(local_symbol_index
,
1690 off
+= (index
- local_symbol_index
) * symsize
;
1691 local_symbol_index
= index
;
1694 unsigned int local_symcount
= local_symbol_index
;
1695 gold_assert(local_symcount
* symsize
== off
- startoff
);
1698 size_t dyn_global_index
;
1700 if (this->dynsym_section_
== NULL
)
1703 dyn_global_index
= 0;
1708 dyn_global_index
= this->dynsym_section_
->info();
1709 off_t locsize
= dyn_global_index
* this->dynsym_section_
->entsize();
1710 dynoff
= this->dynsym_section_
->offset() + locsize
;
1711 dyncount
= (this->dynsym_section_
->data_size() - locsize
) / symsize
;
1712 gold_assert(static_cast<off_t
>(dyncount
* symsize
)
1713 == this->dynsym_section_
->data_size() - locsize
);
1716 off
= symtab
->finalize(off
, dynoff
, dyn_global_index
, dyncount
,
1717 &this->sympool_
, &local_symcount
);
1719 if (!parameters
->strip_all())
1721 this->sympool_
.set_string_offsets();
1723 const char* symtab_name
= this->namepool_
.add(".symtab", false, NULL
);
1724 Output_section
* osymtab
= this->make_output_section(symtab_name
,
1727 this->symtab_section_
= osymtab
;
1729 Output_section_data
* pos
= new Output_data_fixed_space(off
- startoff
,
1731 osymtab
->add_output_section_data(pos
);
1733 const char* strtab_name
= this->namepool_
.add(".strtab", false, NULL
);
1734 Output_section
* ostrtab
= this->make_output_section(strtab_name
,
1738 Output_section_data
* pstr
= new Output_data_strtab(&this->sympool_
);
1739 ostrtab
->add_output_section_data(pstr
);
1741 osymtab
->set_file_offset(startoff
);
1742 osymtab
->finalize_data_size();
1743 osymtab
->set_link_section(ostrtab
);
1744 osymtab
->set_info(local_symcount
);
1745 osymtab
->set_entsize(symsize
);
1751 // Create the .shstrtab section, which holds the names of the
1752 // sections. At the time this is called, we have created all the
1753 // output sections except .shstrtab itself.
1756 Layout::create_shstrtab()
1758 // FIXME: We don't need to create a .shstrtab section if we are
1759 // stripping everything.
1761 const char* name
= this->namepool_
.add(".shstrtab", false, NULL
);
1763 Output_section
* os
= this->make_output_section(name
, elfcpp::SHT_STRTAB
, 0);
1765 // We can't write out this section until we've set all the section
1766 // names, and we don't set the names of compressed output sections
1767 // until relocations are complete.
1768 os
->set_after_input_sections();
1770 Output_section_data
* posd
= new Output_data_strtab(&this->namepool_
);
1771 os
->add_output_section_data(posd
);
1776 // Create the section headers. SIZE is 32 or 64. OFF is the file
1780 Layout::create_shdrs(off_t
* poff
)
1782 Output_section_headers
* oshdrs
;
1783 oshdrs
= new Output_section_headers(this,
1784 &this->segment_list_
,
1785 &this->section_list_
,
1786 &this->unattached_section_list_
,
1788 off_t off
= align_address(*poff
, oshdrs
->addralign());
1789 oshdrs
->set_address_and_file_offset(0, off
);
1790 off
+= oshdrs
->data_size();
1792 this->section_headers_
= oshdrs
;
1795 // Create the dynamic symbol table.
1798 Layout::create_dynamic_symtab(const Input_objects
* input_objects
,
1799 Symbol_table
* symtab
,
1800 Output_section
**pdynstr
,
1801 unsigned int* plocal_dynamic_count
,
1802 std::vector
<Symbol
*>* pdynamic_symbols
,
1803 Versions
* pversions
)
1805 // Count all the symbols in the dynamic symbol table, and set the
1806 // dynamic symbol indexes.
1808 // Skip symbol 0, which is always all zeroes.
1809 unsigned int index
= 1;
1811 // Add STT_SECTION symbols for each Output section which needs one.
1812 for (Section_list::iterator p
= this->section_list_
.begin();
1813 p
!= this->section_list_
.end();
1816 if (!(*p
)->needs_dynsym_index())
1817 (*p
)->set_dynsym_index(-1U);
1820 (*p
)->set_dynsym_index(index
);
1825 // Count the local symbols that need to go in the dynamic symbol table,
1826 // and set the dynamic symbol indexes.
1827 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
1828 p
!= input_objects
->relobj_end();
1831 unsigned int new_index
= (*p
)->set_local_dynsym_indexes(index
);
1835 unsigned int local_symcount
= index
;
1836 *plocal_dynamic_count
= local_symcount
;
1838 // FIXME: We have to tell set_dynsym_indexes whether the
1839 // -E/--export-dynamic option was used.
1840 index
= symtab
->set_dynsym_indexes(index
, pdynamic_symbols
,
1841 &this->dynpool_
, pversions
);
1845 const int size
= parameters
->get_size();
1848 symsize
= elfcpp::Elf_sizes
<32>::sym_size
;
1851 else if (size
== 64)
1853 symsize
= elfcpp::Elf_sizes
<64>::sym_size
;
1859 // Create the dynamic symbol table section.
1861 Output_section
* dynsym
= this->choose_output_section(NULL
, ".dynsym",
1866 Output_section_data
* odata
= new Output_data_fixed_space(index
* symsize
,
1868 dynsym
->add_output_section_data(odata
);
1870 dynsym
->set_info(local_symcount
);
1871 dynsym
->set_entsize(symsize
);
1872 dynsym
->set_addralign(align
);
1874 this->dynsym_section_
= dynsym
;
1876 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
1877 odyn
->add_section_address(elfcpp::DT_SYMTAB
, dynsym
);
1878 odyn
->add_constant(elfcpp::DT_SYMENT
, symsize
);
1880 // Create the dynamic string table section.
1882 Output_section
* dynstr
= this->choose_output_section(NULL
, ".dynstr",
1887 Output_section_data
* strdata
= new Output_data_strtab(&this->dynpool_
);
1888 dynstr
->add_output_section_data(strdata
);
1890 dynsym
->set_link_section(dynstr
);
1891 this->dynamic_section_
->set_link_section(dynstr
);
1893 odyn
->add_section_address(elfcpp::DT_STRTAB
, dynstr
);
1894 odyn
->add_section_size(elfcpp::DT_STRSZ
, dynstr
);
1898 // Create the hash tables.
1900 // FIXME: We need an option to create a GNU hash table.
1902 unsigned char* phash
;
1903 unsigned int hashlen
;
1904 Dynobj::create_elf_hash_table(*pdynamic_symbols
, local_symcount
,
1907 Output_section
* hashsec
= this->choose_output_section(NULL
, ".hash",
1912 Output_section_data
* hashdata
= new Output_data_const_buffer(phash
,
1915 hashsec
->add_output_section_data(hashdata
);
1917 hashsec
->set_link_section(dynsym
);
1918 hashsec
->set_entsize(4);
1920 odyn
->add_section_address(elfcpp::DT_HASH
, hashsec
);
1923 // Assign offsets to each local portion of the dynamic symbol table.
1926 Layout::assign_local_dynsym_offsets(const Input_objects
* input_objects
)
1928 Output_section
* dynsym
= this->dynsym_section_
;
1929 gold_assert(dynsym
!= NULL
);
1931 off_t off
= dynsym
->offset();
1933 // Skip the dummy symbol at the start of the section.
1934 off
+= dynsym
->entsize();
1936 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
1937 p
!= input_objects
->relobj_end();
1940 unsigned int count
= (*p
)->set_local_dynsym_offset(off
);
1941 off
+= count
* dynsym
->entsize();
1945 // Create the version sections.
1948 Layout::create_version_sections(const Versions
* versions
,
1949 const Symbol_table
* symtab
,
1950 unsigned int local_symcount
,
1951 const std::vector
<Symbol
*>& dynamic_symbols
,
1952 const Output_section
* dynstr
)
1954 if (!versions
->any_defs() && !versions
->any_needs())
1957 if (parameters
->get_size() == 32)
1959 if (parameters
->is_big_endian())
1961 #ifdef HAVE_TARGET_32_BIG
1962 this->sized_create_version_sections
1963 SELECT_SIZE_ENDIAN_NAME(32, true)(
1964 versions
, symtab
, local_symcount
, dynamic_symbols
, dynstr
1965 SELECT_SIZE_ENDIAN(32, true));
1972 #ifdef HAVE_TARGET_32_LITTLE
1973 this->sized_create_version_sections
1974 SELECT_SIZE_ENDIAN_NAME(32, false)(
1975 versions
, symtab
, local_symcount
, dynamic_symbols
, dynstr
1976 SELECT_SIZE_ENDIAN(32, false));
1982 else if (parameters
->get_size() == 64)
1984 if (parameters
->is_big_endian())
1986 #ifdef HAVE_TARGET_64_BIG
1987 this->sized_create_version_sections
1988 SELECT_SIZE_ENDIAN_NAME(64, true)(
1989 versions
, symtab
, local_symcount
, dynamic_symbols
, dynstr
1990 SELECT_SIZE_ENDIAN(64, true));
1997 #ifdef HAVE_TARGET_64_LITTLE
1998 this->sized_create_version_sections
1999 SELECT_SIZE_ENDIAN_NAME(64, false)(
2000 versions
, symtab
, local_symcount
, dynamic_symbols
, dynstr
2001 SELECT_SIZE_ENDIAN(64, false));
2011 // Create the version sections, sized version.
2013 template<int size
, bool big_endian
>
2015 Layout::sized_create_version_sections(
2016 const Versions
* versions
,
2017 const Symbol_table
* symtab
,
2018 unsigned int local_symcount
,
2019 const std::vector
<Symbol
*>& dynamic_symbols
,
2020 const Output_section
* dynstr
2023 Output_section
* vsec
= this->choose_output_section(NULL
, ".gnu.version",
2024 elfcpp::SHT_GNU_versym
,
2028 unsigned char* vbuf
;
2030 versions
->symbol_section_contents
SELECT_SIZE_ENDIAN_NAME(size
, big_endian
)(
2031 symtab
, &this->dynpool_
, local_symcount
, dynamic_symbols
, &vbuf
, &vsize
2032 SELECT_SIZE_ENDIAN(size
, big_endian
));
2034 Output_section_data
* vdata
= new Output_data_const_buffer(vbuf
, vsize
, 2);
2036 vsec
->add_output_section_data(vdata
);
2037 vsec
->set_entsize(2);
2038 vsec
->set_link_section(this->dynsym_section_
);
2040 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
2041 odyn
->add_section_address(elfcpp::DT_VERSYM
, vsec
);
2043 if (versions
->any_defs())
2045 Output_section
* vdsec
;
2046 vdsec
= this->choose_output_section(NULL
, ".gnu.version_d",
2047 elfcpp::SHT_GNU_verdef
,
2051 unsigned char* vdbuf
;
2052 unsigned int vdsize
;
2053 unsigned int vdentries
;
2054 versions
->def_section_contents
SELECT_SIZE_ENDIAN_NAME(size
, big_endian
)(
2055 &this->dynpool_
, &vdbuf
, &vdsize
, &vdentries
2056 SELECT_SIZE_ENDIAN(size
, big_endian
));
2058 Output_section_data
* vddata
= new Output_data_const_buffer(vdbuf
,
2062 vdsec
->add_output_section_data(vddata
);
2063 vdsec
->set_link_section(dynstr
);
2064 vdsec
->set_info(vdentries
);
2066 odyn
->add_section_address(elfcpp::DT_VERDEF
, vdsec
);
2067 odyn
->add_constant(elfcpp::DT_VERDEFNUM
, vdentries
);
2070 if (versions
->any_needs())
2072 Output_section
* vnsec
;
2073 vnsec
= this->choose_output_section(NULL
, ".gnu.version_r",
2074 elfcpp::SHT_GNU_verneed
,
2078 unsigned char* vnbuf
;
2079 unsigned int vnsize
;
2080 unsigned int vnentries
;
2081 versions
->need_section_contents
SELECT_SIZE_ENDIAN_NAME(size
, big_endian
)
2082 (&this->dynpool_
, &vnbuf
, &vnsize
, &vnentries
2083 SELECT_SIZE_ENDIAN(size
, big_endian
));
2085 Output_section_data
* vndata
= new Output_data_const_buffer(vnbuf
,
2089 vnsec
->add_output_section_data(vndata
);
2090 vnsec
->set_link_section(dynstr
);
2091 vnsec
->set_info(vnentries
);
2093 odyn
->add_section_address(elfcpp::DT_VERNEED
, vnsec
);
2094 odyn
->add_constant(elfcpp::DT_VERNEEDNUM
, vnentries
);
2098 // Create the .interp section and PT_INTERP segment.
2101 Layout::create_interp(const Target
* target
)
2103 const char* interp
= this->options_
.dynamic_linker();
2106 interp
= target
->dynamic_linker();
2107 gold_assert(interp
!= NULL
);
2110 size_t len
= strlen(interp
) + 1;
2112 Output_section_data
* odata
= new Output_data_const(interp
, len
, 1);
2114 Output_section
* osec
= this->choose_output_section(NULL
, ".interp",
2115 elfcpp::SHT_PROGBITS
,
2118 osec
->add_output_section_data(odata
);
2120 if (!this->script_options_
->saw_phdrs_clause())
2122 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_INTERP
,
2124 oseg
->add_initial_output_section(osec
, elfcpp::PF_R
);
2128 // Finish the .dynamic section and PT_DYNAMIC segment.
2131 Layout::finish_dynamic_section(const Input_objects
* input_objects
,
2132 const Symbol_table
* symtab
)
2134 if (!this->script_options_
->saw_phdrs_clause())
2136 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_DYNAMIC
,
2139 oseg
->add_initial_output_section(this->dynamic_section_
,
2140 elfcpp::PF_R
| elfcpp::PF_W
);
2143 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
2145 for (Input_objects::Dynobj_iterator p
= input_objects
->dynobj_begin();
2146 p
!= input_objects
->dynobj_end();
2149 // FIXME: Handle --as-needed.
2150 odyn
->add_string(elfcpp::DT_NEEDED
, (*p
)->soname());
2153 if (parameters
->output_is_shared())
2155 const char* soname
= this->options_
.soname();
2157 odyn
->add_string(elfcpp::DT_SONAME
, soname
);
2160 // FIXME: Support --init and --fini.
2161 Symbol
* sym
= symtab
->lookup("_init");
2162 if (sym
!= NULL
&& sym
->is_defined() && !sym
->is_from_dynobj())
2163 odyn
->add_symbol(elfcpp::DT_INIT
, sym
);
2165 sym
= symtab
->lookup("_fini");
2166 if (sym
!= NULL
&& sym
->is_defined() && !sym
->is_from_dynobj())
2167 odyn
->add_symbol(elfcpp::DT_FINI
, sym
);
2169 // FIXME: Support DT_INIT_ARRAY and DT_FINI_ARRAY.
2171 // Add a DT_RPATH entry if needed.
2172 const General_options::Dir_list
& rpath(this->options_
.rpath());
2175 std::string rpath_val
;
2176 for (General_options::Dir_list::const_iterator p
= rpath
.begin();
2180 if (rpath_val
.empty())
2181 rpath_val
= p
->name();
2184 // Eliminate duplicates.
2185 General_options::Dir_list::const_iterator q
;
2186 for (q
= rpath
.begin(); q
!= p
; ++q
)
2187 if (q
->name() == p
->name())
2192 rpath_val
+= p
->name();
2197 odyn
->add_string(elfcpp::DT_RPATH
, rpath_val
);
2200 // Look for text segments that have dynamic relocations.
2201 bool have_textrel
= false;
2202 if (!this->script_options_
->saw_sections_clause())
2204 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
2205 p
!= this->segment_list_
.end();
2208 if (((*p
)->flags() & elfcpp::PF_W
) == 0
2209 && (*p
)->dynamic_reloc_count() > 0)
2211 have_textrel
= true;
2218 // We don't know the section -> segment mapping, so we are
2219 // conservative and just look for readonly sections with
2220 // relocations. If those sections wind up in writable segments,
2221 // then we have created an unnecessary DT_TEXTREL entry.
2222 for (Section_list::const_iterator p
= this->section_list_
.begin();
2223 p
!= this->section_list_
.end();
2226 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) != 0
2227 && ((*p
)->flags() & elfcpp::SHF_WRITE
) == 0
2228 && ((*p
)->dynamic_reloc_count() > 0))
2230 have_textrel
= true;
2236 // Add a DT_FLAGS entry. We add it even if no flags are set so that
2237 // post-link tools can easily modify these flags if desired.
2238 unsigned int flags
= 0;
2241 // Add a DT_TEXTREL for compatibility with older loaders.
2242 odyn
->add_constant(elfcpp::DT_TEXTREL
, 0);
2243 flags
|= elfcpp::DF_TEXTREL
;
2245 if (parameters
->output_is_shared() && this->has_static_tls())
2246 flags
|= elfcpp::DF_STATIC_TLS
;
2247 odyn
->add_constant(elfcpp::DT_FLAGS
, flags
);
2250 // The mapping of .gnu.linkonce section names to real section names.
2252 #define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 }
2253 const Layout::Linkonce_mapping
Layout::linkonce_mapping
[] =
2255 MAPPING_INIT("d.rel.ro", ".data.rel.ro"), // Must be before "d".
2256 MAPPING_INIT("t", ".text"),
2257 MAPPING_INIT("r", ".rodata"),
2258 MAPPING_INIT("d", ".data"),
2259 MAPPING_INIT("b", ".bss"),
2260 MAPPING_INIT("s", ".sdata"),
2261 MAPPING_INIT("sb", ".sbss"),
2262 MAPPING_INIT("s2", ".sdata2"),
2263 MAPPING_INIT("sb2", ".sbss2"),
2264 MAPPING_INIT("wi", ".debug_info"),
2265 MAPPING_INIT("td", ".tdata"),
2266 MAPPING_INIT("tb", ".tbss"),
2267 MAPPING_INIT("lr", ".lrodata"),
2268 MAPPING_INIT("l", ".ldata"),
2269 MAPPING_INIT("lb", ".lbss"),
2273 const int Layout::linkonce_mapping_count
=
2274 sizeof(Layout::linkonce_mapping
) / sizeof(Layout::linkonce_mapping
[0]);
2276 // Return the name of the output section to use for a .gnu.linkonce
2277 // section. This is based on the default ELF linker script of the old
2278 // GNU linker. For example, we map a name like ".gnu.linkonce.t.foo"
2279 // to ".text". Set *PLEN to the length of the name. *PLEN is
2280 // initialized to the length of NAME.
2283 Layout::linkonce_output_name(const char* name
, size_t *plen
)
2285 const char* s
= name
+ sizeof(".gnu.linkonce") - 1;
2289 const Linkonce_mapping
* plm
= linkonce_mapping
;
2290 for (int i
= 0; i
< linkonce_mapping_count
; ++i
, ++plm
)
2292 if (strncmp(s
, plm
->from
, plm
->fromlen
) == 0 && s
[plm
->fromlen
] == '.')
2301 // Choose the output section name to use given an input section name.
2302 // Set *PLEN to the length of the name. *PLEN is initialized to the
2306 Layout::output_section_name(const char* name
, size_t* plen
)
2308 if (Layout::is_linkonce(name
))
2310 // .gnu.linkonce sections are laid out as though they were named
2311 // for the sections are placed into.
2312 return Layout::linkonce_output_name(name
, plen
);
2315 // gcc 4.3 generates the following sorts of section names when it
2316 // needs a section name specific to a function:
2322 // .data.rel.local.FN
2324 // .data.rel.ro.local.FN
2331 // The GNU linker maps all of those to the part before the .FN,
2332 // except that .data.rel.local.FN is mapped to .data, and
2333 // .data.rel.ro.local.FN is mapped to .data.rel.ro. The sections
2334 // beginning with .data.rel.ro.local are grouped together.
2336 // For an anonymous namespace, the string FN can contain a '.'.
2338 // Also of interest: .rodata.strN.N, .rodata.cstN, both of which the
2339 // GNU linker maps to .rodata.
2341 // The .data.rel.ro sections enable a security feature triggered by
2342 // the -z relro option. Section which need to be relocated at
2343 // program startup time but which may be readonly after startup are
2344 // grouped into .data.rel.ro. They are then put into a PT_GNU_RELRO
2345 // segment. The dynamic linker will make that segment writable,
2346 // perform relocations, and then make it read-only. FIXME: We do
2347 // not yet implement this optimization.
2349 // It is hard to handle this in a principled way.
2351 // These are the rules we follow:
2353 // If the section name has no initial '.', or no dot other than an
2354 // initial '.', we use the name unchanged (i.e., "mysection" and
2355 // ".text" are unchanged).
2357 // If the name starts with ".data.rel.ro" we use ".data.rel.ro".
2359 // Otherwise, we drop the second '.' and everything that comes after
2360 // it (i.e., ".text.XXX" becomes ".text").
2362 const char* s
= name
;
2366 const char* sdot
= strchr(s
, '.');
2370 const char* const data_rel_ro
= ".data.rel.ro";
2371 if (strncmp(name
, data_rel_ro
, strlen(data_rel_ro
)) == 0)
2373 *plen
= strlen(data_rel_ro
);
2377 *plen
= sdot
- name
;
2381 // Record the signature of a comdat section, and return whether to
2382 // include it in the link. If GROUP is true, this is a regular
2383 // section group. If GROUP is false, this is a group signature
2384 // derived from the name of a linkonce section. We want linkonce
2385 // signatures and group signatures to block each other, but we don't
2386 // want a linkonce signature to block another linkonce signature.
2389 Layout::add_comdat(const char* signature
, bool group
)
2391 std::string
sig(signature
);
2392 std::pair
<Signatures::iterator
, bool> ins(
2393 this->signatures_
.insert(std::make_pair(sig
, group
)));
2397 // This is the first time we've seen this signature.
2401 if (ins
.first
->second
)
2403 // We've already seen a real section group with this signature.
2408 // This is a real section group, and we've already seen a
2409 // linkonce section with this signature. Record that we've seen
2410 // a section group, and don't include this section group.
2411 ins
.first
->second
= true;
2416 // We've already seen a linkonce section and this is a linkonce
2417 // section. These don't block each other--this may be the same
2418 // symbol name with different section types.
2423 // Store the allocated sections into the section list.
2426 Layout::get_allocated_sections(Section_list
* section_list
) const
2428 for (Section_list::const_iterator p
= this->section_list_
.begin();
2429 p
!= this->section_list_
.end();
2431 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) != 0)
2432 section_list
->push_back(*p
);
2435 // Create an output segment.
2438 Layout::make_output_segment(elfcpp::Elf_Word type
, elfcpp::Elf_Word flags
)
2440 gold_assert(!parameters
->output_is_object());
2441 Output_segment
* oseg
= new Output_segment(type
, flags
);
2442 this->segment_list_
.push_back(oseg
);
2446 // Write out the Output_sections. Most won't have anything to write,
2447 // since most of the data will come from input sections which are
2448 // handled elsewhere. But some Output_sections do have Output_data.
2451 Layout::write_output_sections(Output_file
* of
) const
2453 for (Section_list::const_iterator p
= this->section_list_
.begin();
2454 p
!= this->section_list_
.end();
2457 if (!(*p
)->after_input_sections())
2462 // Write out data not associated with a section or the symbol table.
2465 Layout::write_data(const Symbol_table
* symtab
, Output_file
* of
) const
2467 if (!parameters
->strip_all())
2469 const Output_section
* symtab_section
= this->symtab_section_
;
2470 for (Section_list::const_iterator p
= this->section_list_
.begin();
2471 p
!= this->section_list_
.end();
2474 if ((*p
)->needs_symtab_index())
2476 gold_assert(symtab_section
!= NULL
);
2477 unsigned int index
= (*p
)->symtab_index();
2478 gold_assert(index
> 0 && index
!= -1U);
2479 off_t off
= (symtab_section
->offset()
2480 + index
* symtab_section
->entsize());
2481 symtab
->write_section_symbol(*p
, of
, off
);
2486 const Output_section
* dynsym_section
= this->dynsym_section_
;
2487 for (Section_list::const_iterator p
= this->section_list_
.begin();
2488 p
!= this->section_list_
.end();
2491 if ((*p
)->needs_dynsym_index())
2493 gold_assert(dynsym_section
!= NULL
);
2494 unsigned int index
= (*p
)->dynsym_index();
2495 gold_assert(index
> 0 && index
!= -1U);
2496 off_t off
= (dynsym_section
->offset()
2497 + index
* dynsym_section
->entsize());
2498 symtab
->write_section_symbol(*p
, of
, off
);
2502 // Write out the Output_data which are not in an Output_section.
2503 for (Data_list::const_iterator p
= this->special_output_list_
.begin();
2504 p
!= this->special_output_list_
.end();
2509 // Write out the Output_sections which can only be written after the
2510 // input sections are complete.
2513 Layout::write_sections_after_input_sections(Output_file
* of
)
2515 // Determine the final section offsets, and thus the final output
2516 // file size. Note we finalize the .shstrab last, to allow the
2517 // after_input_section sections to modify their section-names before
2519 if (this->any_postprocessing_sections_
)
2521 off_t off
= this->output_file_size_
;
2522 off
= this->set_section_offsets(off
, POSTPROCESSING_SECTIONS_PASS
);
2524 // Now that we've finalized the names, we can finalize the shstrab.
2526 this->set_section_offsets(off
,
2527 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
);
2529 if (off
> this->output_file_size_
)
2532 this->output_file_size_
= off
;
2536 for (Section_list::const_iterator p
= this->section_list_
.begin();
2537 p
!= this->section_list_
.end();
2540 if ((*p
)->after_input_sections())
2544 this->section_headers_
->write(of
);
2547 // Write out a binary file. This is called after the link is
2548 // complete. IN is the temporary output file we used to generate the
2549 // ELF code. We simply walk through the segments, read them from
2550 // their file offset in IN, and write them to their load address in
2551 // the output file. FIXME: with a bit more work, we could support
2552 // S-records and/or Intel hex format here.
2555 Layout::write_binary(Output_file
* in
) const
2557 gold_assert(this->options_
.oformat()
2558 == General_options::OBJECT_FORMAT_BINARY
);
2560 // Get the size of the binary file.
2561 uint64_t max_load_address
= 0;
2562 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
2563 p
!= this->segment_list_
.end();
2566 if ((*p
)->type() == elfcpp::PT_LOAD
&& (*p
)->filesz() > 0)
2568 uint64_t max_paddr
= (*p
)->paddr() + (*p
)->filesz();
2569 if (max_paddr
> max_load_address
)
2570 max_load_address
= max_paddr
;
2574 Output_file
out(parameters
->output_file_name());
2575 out
.open(max_load_address
);
2577 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
2578 p
!= this->segment_list_
.end();
2581 if ((*p
)->type() == elfcpp::PT_LOAD
&& (*p
)->filesz() > 0)
2583 const unsigned char* vin
= in
->get_input_view((*p
)->offset(),
2585 unsigned char* vout
= out
.get_output_view((*p
)->paddr(),
2587 memcpy(vout
, vin
, (*p
)->filesz());
2588 out
.write_output_view((*p
)->paddr(), (*p
)->filesz(), vout
);
2589 in
->free_input_view((*p
)->offset(), (*p
)->filesz(), vin
);
2596 // Print statistical information to stderr. This is used for --stats.
2599 Layout::print_stats() const
2601 this->namepool_
.print_stats("section name pool");
2602 this->sympool_
.print_stats("output symbol name pool");
2603 this->dynpool_
.print_stats("dynamic name pool");
2605 for (Section_list::const_iterator p
= this->section_list_
.begin();
2606 p
!= this->section_list_
.end();
2608 (*p
)->print_merge_stats();
2611 // Write_sections_task methods.
2613 // We can always run this task.
2616 Write_sections_task::is_runnable()
2621 // We need to unlock both OUTPUT_SECTIONS_BLOCKER and FINAL_BLOCKER
2625 Write_sections_task::locks(Task_locker
* tl
)
2627 tl
->add(this, this->output_sections_blocker_
);
2628 tl
->add(this, this->final_blocker_
);
2631 // Run the task--write out the data.
2634 Write_sections_task::run(Workqueue
*)
2636 this->layout_
->write_output_sections(this->of_
);
2639 // Write_data_task methods.
2641 // We can always run this task.
2644 Write_data_task::is_runnable()
2649 // We need to unlock FINAL_BLOCKER when finished.
2652 Write_data_task::locks(Task_locker
* tl
)
2654 tl
->add(this, this->final_blocker_
);
2657 // Run the task--write out the data.
2660 Write_data_task::run(Workqueue
*)
2662 this->layout_
->write_data(this->symtab_
, this->of_
);
2665 // Write_symbols_task methods.
2667 // We can always run this task.
2670 Write_symbols_task::is_runnable()
2675 // We need to unlock FINAL_BLOCKER when finished.
2678 Write_symbols_task::locks(Task_locker
* tl
)
2680 tl
->add(this, this->final_blocker_
);
2683 // Run the task--write out the symbols.
2686 Write_symbols_task::run(Workqueue
*)
2688 this->symtab_
->write_globals(this->input_objects_
, this->sympool_
,
2689 this->dynpool_
, this->of_
);
2692 // Write_after_input_sections_task methods.
2694 // We can only run this task after the input sections have completed.
2697 Write_after_input_sections_task::is_runnable()
2699 if (this->input_sections_blocker_
->is_blocked())
2700 return this->input_sections_blocker_
;
2704 // We need to unlock FINAL_BLOCKER when finished.
2707 Write_after_input_sections_task::locks(Task_locker
* tl
)
2709 tl
->add(this, this->final_blocker_
);
2715 Write_after_input_sections_task::run(Workqueue
*)
2717 this->layout_
->write_sections_after_input_sections(this->of_
);
2720 // Close_task_runner methods.
2722 // Run the task--close the file.
2725 Close_task_runner::run(Workqueue
*, const Task
*)
2727 // If we've been asked to create a binary file, we do so here.
2728 if (this->options_
->oformat() != General_options::OBJECT_FORMAT_ELF
)
2729 this->layout_
->write_binary(this->of_
);
2734 // Instantiate the templates we need. We could use the configure
2735 // script to restrict this to only the ones for implemented targets.
2737 #ifdef HAVE_TARGET_32_LITTLE
2740 Layout::layout
<32, false>(Sized_relobj
<32, false>* object
, unsigned int shndx
,
2742 const elfcpp::Shdr
<32, false>& shdr
,
2743 unsigned int, unsigned int, off_t
*);
2746 #ifdef HAVE_TARGET_32_BIG
2749 Layout::layout
<32, true>(Sized_relobj
<32, true>* object
, unsigned int shndx
,
2751 const elfcpp::Shdr
<32, true>& shdr
,
2752 unsigned int, unsigned int, off_t
*);
2755 #ifdef HAVE_TARGET_64_LITTLE
2758 Layout::layout
<64, false>(Sized_relobj
<64, false>* object
, unsigned int shndx
,
2760 const elfcpp::Shdr
<64, false>& shdr
,
2761 unsigned int, unsigned int, off_t
*);
2764 #ifdef HAVE_TARGET_64_BIG
2767 Layout::layout
<64, true>(Sized_relobj
<64, true>* object
, unsigned int shndx
,
2769 const elfcpp::Shdr
<64, true>& shdr
,
2770 unsigned int, unsigned int, off_t
*);
2773 #ifdef HAVE_TARGET_32_LITTLE
2776 Layout::layout_reloc
<32, false>(Sized_relobj
<32, false>* object
,
2777 unsigned int reloc_shndx
,
2778 const elfcpp::Shdr
<32, false>& shdr
,
2779 Output_section
* data_section
,
2780 Relocatable_relocs
* rr
);
2783 #ifdef HAVE_TARGET_32_BIG
2786 Layout::layout_reloc
<32, true>(Sized_relobj
<32, true>* object
,
2787 unsigned int reloc_shndx
,
2788 const elfcpp::Shdr
<32, true>& shdr
,
2789 Output_section
* data_section
,
2790 Relocatable_relocs
* rr
);
2793 #ifdef HAVE_TARGET_64_LITTLE
2796 Layout::layout_reloc
<64, false>(Sized_relobj
<64, false>* object
,
2797 unsigned int reloc_shndx
,
2798 const elfcpp::Shdr
<64, false>& shdr
,
2799 Output_section
* data_section
,
2800 Relocatable_relocs
* rr
);
2803 #ifdef HAVE_TARGET_64_BIG
2806 Layout::layout_reloc
<64, true>(Sized_relobj
<64, true>* object
,
2807 unsigned int reloc_shndx
,
2808 const elfcpp::Shdr
<64, true>& shdr
,
2809 Output_section
* data_section
,
2810 Relocatable_relocs
* rr
);
2813 #ifdef HAVE_TARGET_32_LITTLE
2816 Layout::layout_group
<32, false>(Symbol_table
* symtab
,
2817 Sized_relobj
<32, false>* object
,
2819 const char* group_section_name
,
2820 const char* signature
,
2821 const elfcpp::Shdr
<32, false>& shdr
,
2822 const elfcpp::Elf_Word
* contents
);
2825 #ifdef HAVE_TARGET_32_BIG
2828 Layout::layout_group
<32, true>(Symbol_table
* symtab
,
2829 Sized_relobj
<32, true>* object
,
2831 const char* group_section_name
,
2832 const char* signature
,
2833 const elfcpp::Shdr
<32, true>& shdr
,
2834 const elfcpp::Elf_Word
* contents
);
2837 #ifdef HAVE_TARGET_64_LITTLE
2840 Layout::layout_group
<64, false>(Symbol_table
* symtab
,
2841 Sized_relobj
<64, false>* object
,
2843 const char* group_section_name
,
2844 const char* signature
,
2845 const elfcpp::Shdr
<64, false>& shdr
,
2846 const elfcpp::Elf_Word
* contents
);
2849 #ifdef HAVE_TARGET_64_BIG
2852 Layout::layout_group
<64, true>(Symbol_table
* symtab
,
2853 Sized_relobj
<64, true>* object
,
2855 const char* group_section_name
,
2856 const char* signature
,
2857 const elfcpp::Shdr
<64, true>& shdr
,
2858 const elfcpp::Elf_Word
* contents
);
2861 #ifdef HAVE_TARGET_32_LITTLE
2864 Layout::layout_eh_frame
<32, false>(Sized_relobj
<32, false>* object
,
2865 const unsigned char* symbols
,
2867 const unsigned char* symbol_names
,
2868 off_t symbol_names_size
,
2870 const elfcpp::Shdr
<32, false>& shdr
,
2871 unsigned int reloc_shndx
,
2872 unsigned int reloc_type
,
2876 #ifdef HAVE_TARGET_32_BIG
2879 Layout::layout_eh_frame
<32, true>(Sized_relobj
<32, true>* object
,
2880 const unsigned char* symbols
,
2882 const unsigned char* symbol_names
,
2883 off_t symbol_names_size
,
2885 const elfcpp::Shdr
<32, true>& shdr
,
2886 unsigned int reloc_shndx
,
2887 unsigned int reloc_type
,
2891 #ifdef HAVE_TARGET_64_LITTLE
2894 Layout::layout_eh_frame
<64, false>(Sized_relobj
<64, false>* object
,
2895 const unsigned char* symbols
,
2897 const unsigned char* symbol_names
,
2898 off_t symbol_names_size
,
2900 const elfcpp::Shdr
<64, false>& shdr
,
2901 unsigned int reloc_shndx
,
2902 unsigned int reloc_type
,
2906 #ifdef HAVE_TARGET_64_BIG
2909 Layout::layout_eh_frame
<64, true>(Sized_relobj
<64, true>* object
,
2910 const unsigned char* symbols
,
2912 const unsigned char* symbol_names
,
2913 off_t symbol_names_size
,
2915 const elfcpp::Shdr
<64, true>& shdr
,
2916 unsigned int reloc_shndx
,
2917 unsigned int reloc_type
,
2921 } // End namespace gold.