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_
,
58 // Now we know the final size of the output file and we know where
59 // each piece of information goes.
60 Output_file
* of
= new Output_file(parameters
->options().output_file_name());
61 if (this->options_
.oformat_enum() != General_options::OBJECT_FORMAT_ELF
)
62 of
->set_is_temporary();
65 // Queue up the final set of tasks.
66 gold::queue_final_tasks(this->options_
, this->input_objects_
,
67 this->symtab_
, this->layout_
, workqueue
, of
);
72 Layout::Layout(const General_options
& options
, Script_options
* script_options
)
73 : options_(options
), script_options_(script_options
), namepool_(),
74 sympool_(), dynpool_(), signatures_(),
75 section_name_map_(), segment_list_(), section_list_(),
76 unattached_section_list_(), special_output_list_(),
77 section_headers_(NULL
), tls_segment_(NULL
), symtab_section_(NULL
),
78 dynsym_section_(NULL
), dynamic_section_(NULL
), dynamic_data_(NULL
),
79 eh_frame_section_(NULL
), group_signatures_(), output_file_size_(-1),
80 input_requires_executable_stack_(false),
81 input_with_gnu_stack_note_(false),
82 input_without_gnu_stack_note_(false),
83 has_static_tls_(false),
84 any_postprocessing_sections_(false)
86 // Make space for more than enough segments for a typical file.
87 // This is just for efficiency--it's OK if we wind up needing more.
88 this->segment_list_
.reserve(12);
90 // We expect two unattached Output_data objects: the file header and
91 // the segment headers.
92 this->special_output_list_
.reserve(2);
95 // Hash a key we use to look up an output section mapping.
98 Layout::Hash_key::operator()(const Layout::Key
& k
) const
100 return k
.first
+ k
.second
.first
+ k
.second
.second
;
103 // Return whether PREFIX is a prefix of STR.
106 is_prefix_of(const char* prefix
, const char* str
)
108 return strncmp(prefix
, str
, strlen(prefix
)) == 0;
111 // Returns whether the given section is in the list of
112 // debug-sections-used-by-some-version-of-gdb. Currently,
113 // we've checked versions of gdb up to and including 6.7.1.
115 static const char* gdb_sections
[] =
117 // ".debug_aranges", // not used by gdb as of 6.7.1
123 // ".debug_pubnames", // not used by gdb as of 6.7.1
129 is_gdb_debug_section(const char* str
)
131 // We can do this faster: binary search or a hashtable. But why bother?
132 for (size_t i
= 0; i
< sizeof(gdb_sections
)/sizeof(*gdb_sections
); ++i
)
133 if (strcmp(str
, gdb_sections
[i
]) == 0)
138 // Whether to include this section in the link.
140 template<int size
, bool big_endian
>
142 Layout::include_section(Sized_relobj
<size
, big_endian
>*, const char* name
,
143 const elfcpp::Shdr
<size
, big_endian
>& shdr
)
145 switch (shdr
.get_sh_type())
147 case elfcpp::SHT_NULL
:
148 case elfcpp::SHT_SYMTAB
:
149 case elfcpp::SHT_DYNSYM
:
150 case elfcpp::SHT_STRTAB
:
151 case elfcpp::SHT_HASH
:
152 case elfcpp::SHT_DYNAMIC
:
153 case elfcpp::SHT_SYMTAB_SHNDX
:
156 case elfcpp::SHT_RELA
:
157 case elfcpp::SHT_REL
:
158 case elfcpp::SHT_GROUP
:
159 // If we are emitting relocations these should be handled
161 gold_assert(!parameters
->options().relocatable()
162 && !parameters
->options().emit_relocs());
165 case elfcpp::SHT_PROGBITS
:
166 if (parameters
->options().strip_debug()
167 && (shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) == 0)
169 // Debugging sections can only be recognized by name.
170 if (is_prefix_of(".debug", name
)
171 || is_prefix_of(".gnu.linkonce.wi.", name
)
172 || is_prefix_of(".line", name
)
173 || is_prefix_of(".stab", name
))
176 if (parameters
->options().strip_debug_gdb()
177 && (shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) == 0)
179 // Debugging sections can only be recognized by name.
180 if (is_prefix_of(".debug", name
)
181 && !is_gdb_debug_section(name
))
191 // Return an output section named NAME, or NULL if there is none.
194 Layout::find_output_section(const char* name
) const
196 for (Section_list::const_iterator p
= this->section_list_
.begin();
197 p
!= this->section_list_
.end();
199 if (strcmp((*p
)->name(), name
) == 0)
204 // Return an output segment of type TYPE, with segment flags SET set
205 // and segment flags CLEAR clear. Return NULL if there is none.
208 Layout::find_output_segment(elfcpp::PT type
, elfcpp::Elf_Word set
,
209 elfcpp::Elf_Word clear
) const
211 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
212 p
!= this->segment_list_
.end();
214 if (static_cast<elfcpp::PT
>((*p
)->type()) == type
215 && ((*p
)->flags() & set
) == set
216 && ((*p
)->flags() & clear
) == 0)
221 // Return the output section to use for section NAME with type TYPE
222 // and section flags FLAGS. NAME must be canonicalized in the string
223 // pool, and NAME_KEY is the key.
226 Layout::get_output_section(const char* name
, Stringpool::Key name_key
,
227 elfcpp::Elf_Word type
, elfcpp::Elf_Xword flags
)
229 const Key
key(name_key
, std::make_pair(type
, flags
));
230 const std::pair
<Key
, Output_section
*> v(key
, NULL
);
231 std::pair
<Section_name_map::iterator
, bool> ins(
232 this->section_name_map_
.insert(v
));
235 return ins
.first
->second
;
238 // This is the first time we've seen this name/type/flags
239 // combination. For compatibility with the GNU linker, we
240 // combine sections with contents and zero flags with sections
241 // with non-zero flags. This is a workaround for cases where
242 // assembler code forgets to set section flags. FIXME: Perhaps
243 // there should be an option to control this.
244 Output_section
* os
= NULL
;
246 if (type
== elfcpp::SHT_PROGBITS
)
250 Output_section
* same_name
= this->find_output_section(name
);
251 if (same_name
!= NULL
252 && same_name
->type() == elfcpp::SHT_PROGBITS
253 && (same_name
->flags() & elfcpp::SHF_TLS
) == 0)
256 else if ((flags
& elfcpp::SHF_TLS
) == 0)
258 elfcpp::Elf_Xword zero_flags
= 0;
259 const Key
zero_key(name_key
, std::make_pair(type
, zero_flags
));
260 Section_name_map::iterator p
=
261 this->section_name_map_
.find(zero_key
);
262 if (p
!= this->section_name_map_
.end())
265 if ((flags
& elfcpp::SHF_ALLOC
) != 0)
266 this->allocate_output_section(os
, flags
);
272 os
= this->make_output_section(name
, type
, flags
);
273 ins
.first
->second
= os
;
278 // Pick the output section to use for section NAME, in input file
279 // RELOBJ, with type TYPE and flags FLAGS. RELOBJ may be NULL for a
280 // linker created section. ADJUST_NAME is true if we should apply the
281 // standard name mappings in Layout::output_section_name. This will
282 // return NULL if the input section should be discarded.
285 Layout::choose_output_section(const Relobj
* relobj
, const char* name
,
286 elfcpp::Elf_Word type
, elfcpp::Elf_Xword flags
,
289 // We should ignore some flags. FIXME: This will need some
290 // adjustment for ld -r.
291 flags
&= ~ (elfcpp::SHF_INFO_LINK
292 | elfcpp::SHF_LINK_ORDER
295 | elfcpp::SHF_STRINGS
);
297 if (this->script_options_
->saw_sections_clause())
299 // We are using a SECTIONS clause, so the output section is
300 // chosen based only on the name.
302 Script_sections
* ss
= this->script_options_
->script_sections();
303 const char* file_name
= relobj
== NULL
? NULL
: relobj
->name().c_str();
304 Output_section
** output_section_slot
;
305 name
= ss
->output_section_name(file_name
, name
, &output_section_slot
);
308 // The SECTIONS clause says to discard this input section.
312 // If this is an orphan section--one not mentioned in the linker
313 // script--then OUTPUT_SECTION_SLOT will be NULL, and we do the
314 // default processing below.
316 if (output_section_slot
!= NULL
)
318 if (*output_section_slot
!= NULL
)
320 // If the output section was created unallocated, and we
321 // are now allocating it, then we need to clear the
322 // address set in the constructor and remove it from the
323 // unattached section list.
324 if (((*output_section_slot
)->flags() & elfcpp::SHF_ALLOC
) == 0
325 && (flags
& elfcpp::SHF_ALLOC
) != 0)
326 this->allocate_output_section(*output_section_slot
, flags
);
328 return *output_section_slot
;
331 // We don't put sections found in the linker script into
332 // SECTION_NAME_MAP_. That keeps us from getting confused
333 // if an orphan section is mapped to a section with the same
334 // name as one in the linker script.
336 name
= this->namepool_
.add(name
, false, NULL
);
338 Output_section
* os
= this->make_output_section(name
, type
, flags
);
339 os
->set_found_in_sections_clause();
340 *output_section_slot
= os
;
345 // FIXME: Handle SHF_OS_NONCONFORMING somewhere.
347 // Turn NAME from the name of the input section into the name of the
350 size_t len
= strlen(name
);
351 if (adjust_name
&& !parameters
->options().relocatable())
352 name
= Layout::output_section_name(name
, &len
);
354 Stringpool::Key name_key
;
355 name
= this->namepool_
.add_with_length(name
, len
, true, &name_key
);
357 // Find or make the output section. The output section is selected
358 // based on the section name, type, and flags.
359 return this->get_output_section(name
, name_key
, type
, flags
);
362 // Return the output section to use for input section SHNDX, with name
363 // NAME, with header HEADER, from object OBJECT. RELOC_SHNDX is the
364 // index of a relocation section which applies to this section, or 0
365 // if none, or -1U if more than one. RELOC_TYPE is the type of the
366 // relocation section if there is one. Set *OFF to the offset of this
367 // input section without the output section. Return NULL if the
368 // section should be discarded. Set *OFF to -1 if the section
369 // contents should not be written directly to the output file, but
370 // will instead receive special handling.
372 template<int size
, bool big_endian
>
374 Layout::layout(Sized_relobj
<size
, big_endian
>* object
, unsigned int shndx
,
375 const char* name
, const elfcpp::Shdr
<size
, big_endian
>& shdr
,
376 unsigned int reloc_shndx
, unsigned int, off_t
* off
)
378 if (!this->include_section(object
, name
, shdr
))
383 // In a relocatable link a grouped section must not be combined with
384 // any other sections.
385 if (parameters
->options().relocatable()
386 && (shdr
.get_sh_flags() & elfcpp::SHF_GROUP
) != 0)
388 name
= this->namepool_
.add(name
, true, NULL
);
389 os
= this->make_output_section(name
, shdr
.get_sh_type(),
390 shdr
.get_sh_flags());
394 os
= this->choose_output_section(object
, name
, shdr
.get_sh_type(),
395 shdr
.get_sh_flags(), true);
400 // FIXME: Handle SHF_LINK_ORDER somewhere.
402 *off
= os
->add_input_section(object
, shndx
, name
, shdr
, reloc_shndx
,
403 this->script_options_
->saw_sections_clause());
408 // Handle a relocation section when doing a relocatable link.
410 template<int size
, bool big_endian
>
412 Layout::layout_reloc(Sized_relobj
<size
, big_endian
>* object
,
414 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
415 Output_section
* data_section
,
416 Relocatable_relocs
* rr
)
418 gold_assert(parameters
->options().relocatable()
419 || parameters
->options().emit_relocs());
421 int sh_type
= shdr
.get_sh_type();
424 if (sh_type
== elfcpp::SHT_REL
)
426 else if (sh_type
== elfcpp::SHT_RELA
)
430 name
+= data_section
->name();
432 Output_section
* os
= this->choose_output_section(object
, name
.c_str(),
437 os
->set_should_link_to_symtab();
438 os
->set_info_section(data_section
);
440 Output_section_data
* posd
;
441 if (sh_type
== elfcpp::SHT_REL
)
443 os
->set_entsize(elfcpp::Elf_sizes
<size
>::rel_size
);
444 posd
= new Output_relocatable_relocs
<elfcpp::SHT_REL
,
448 else if (sh_type
== elfcpp::SHT_RELA
)
450 os
->set_entsize(elfcpp::Elf_sizes
<size
>::rela_size
);
451 posd
= new Output_relocatable_relocs
<elfcpp::SHT_RELA
,
458 os
->add_output_section_data(posd
);
459 rr
->set_output_data(posd
);
464 // Handle a group section when doing a relocatable link.
466 template<int size
, bool big_endian
>
468 Layout::layout_group(Symbol_table
* symtab
,
469 Sized_relobj
<size
, big_endian
>* object
,
471 const char* group_section_name
,
472 const char* signature
,
473 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
474 const elfcpp::Elf_Word
* contents
)
476 gold_assert(parameters
->options().relocatable());
477 gold_assert(shdr
.get_sh_type() == elfcpp::SHT_GROUP
);
478 group_section_name
= this->namepool_
.add(group_section_name
, true, NULL
);
479 Output_section
* os
= this->make_output_section(group_section_name
,
481 shdr
.get_sh_flags());
483 // We need to find a symbol with the signature in the symbol table.
484 // If we don't find one now, we need to look again later.
485 Symbol
* sym
= symtab
->lookup(signature
, NULL
);
487 os
->set_info_symndx(sym
);
490 // We will wind up using a symbol whose name is the signature.
491 // So just put the signature in the symbol name pool to save it.
492 signature
= symtab
->canonicalize_name(signature
);
493 this->group_signatures_
.push_back(Group_signature(os
, signature
));
496 os
->set_should_link_to_symtab();
499 section_size_type entry_count
=
500 convert_to_section_size_type(shdr
.get_sh_size() / 4);
501 Output_section_data
* posd
=
502 new Output_data_group
<size
, big_endian
>(object
, entry_count
, contents
);
503 os
->add_output_section_data(posd
);
506 // Special GNU handling of sections name .eh_frame. They will
507 // normally hold exception frame data as defined by the C++ ABI
508 // (http://codesourcery.com/cxx-abi/).
510 template<int size
, bool big_endian
>
512 Layout::layout_eh_frame(Sized_relobj
<size
, big_endian
>* object
,
513 const unsigned char* symbols
,
515 const unsigned char* symbol_names
,
516 off_t symbol_names_size
,
518 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
519 unsigned int reloc_shndx
, unsigned int reloc_type
,
522 gold_assert(shdr
.get_sh_type() == elfcpp::SHT_PROGBITS
);
523 gold_assert((shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) != 0);
525 const char* const name
= ".eh_frame";
526 Output_section
* os
= this->choose_output_section(object
,
528 elfcpp::SHT_PROGBITS
,
534 // On some targets gcc assumes that a read-only .eh_frame section
535 // will be merged with a read-write .eh_frame section.
536 if ((shdr
.get_sh_flags() & elfcpp::SHF_WRITE
) != 0
537 && (os
->flags() & elfcpp::SHF_WRITE
) == 0)
539 elfcpp::Elf_Xword new_flags
= os
->flags() | elfcpp::SHF_WRITE
;
540 this->write_enable_output_section(os
, new_flags
);
541 os
->set_flags(new_flags
);
544 if (this->eh_frame_section_
== NULL
)
546 this->eh_frame_section_
= os
;
547 this->eh_frame_data_
= new Eh_frame();
548 os
->add_output_section_data(this->eh_frame_data_
);
550 if (this->options_
.eh_frame_hdr())
552 Output_section
* hdr_os
=
553 this->choose_output_section(NULL
,
555 elfcpp::SHT_PROGBITS
,
561 Eh_frame_hdr
* hdr_posd
= new Eh_frame_hdr(os
,
562 this->eh_frame_data_
);
563 hdr_os
->add_output_section_data(hdr_posd
);
565 hdr_os
->set_after_input_sections();
567 if (!this->script_options_
->saw_phdrs_clause())
569 Output_segment
* hdr_oseg
;
570 hdr_oseg
= this->make_output_segment(elfcpp::PT_GNU_EH_FRAME
,
572 hdr_oseg
->add_output_section(hdr_os
, elfcpp::PF_R
);
575 this->eh_frame_data_
->set_eh_frame_hdr(hdr_posd
);
580 gold_assert(this->eh_frame_section_
== os
);
582 if (this->eh_frame_data_
->add_ehframe_input_section(object
,
593 // We couldn't handle this .eh_frame section for some reason.
594 // Add it as a normal section.
595 bool saw_sections_clause
= this->script_options_
->saw_sections_clause();
596 *off
= os
->add_input_section(object
, shndx
, name
, shdr
, reloc_shndx
,
597 saw_sections_clause
);
603 // Add POSD to an output section using NAME, TYPE, and FLAGS.
606 Layout::add_output_section_data(const char* name
, elfcpp::Elf_Word type
,
607 elfcpp::Elf_Xword flags
,
608 Output_section_data
* posd
)
610 Output_section
* os
= this->choose_output_section(NULL
, name
, type
, flags
,
613 os
->add_output_section_data(posd
);
616 // Map section flags to segment flags.
619 Layout::section_flags_to_segment(elfcpp::Elf_Xword flags
)
621 elfcpp::Elf_Word ret
= elfcpp::PF_R
;
622 if ((flags
& elfcpp::SHF_WRITE
) != 0)
624 if ((flags
& elfcpp::SHF_EXECINSTR
) != 0)
629 // Sometimes we compress sections. This is typically done for
630 // sections that are not part of normal program execution (such as
631 // .debug_* sections), and where the readers of these sections know
632 // how to deal with compressed sections. (To make it easier for them,
633 // we will rename the ouput section in such cases from .foo to
634 // .foo.zlib.nnnn, where nnnn is the uncompressed size.) This routine
635 // doesn't say for certain whether we'll compress -- it depends on
636 // commandline options as well -- just whether this section is a
637 // candidate for compression.
640 is_compressible_debug_section(const char* secname
)
642 return (strncmp(secname
, ".debug", sizeof(".debug") - 1) == 0);
645 // Make a new Output_section, and attach it to segments as
649 Layout::make_output_section(const char* name
, elfcpp::Elf_Word type
,
650 elfcpp::Elf_Xword flags
)
653 if ((flags
& elfcpp::SHF_ALLOC
) == 0
654 && strcmp(this->options_
.compress_debug_sections(), "none") != 0
655 && is_compressible_debug_section(name
))
656 os
= new Output_compressed_section(&this->options_
, name
, type
, flags
);
658 os
= new Output_section(name
, type
, flags
);
660 this->section_list_
.push_back(os
);
662 if ((flags
& elfcpp::SHF_ALLOC
) == 0)
663 this->unattached_section_list_
.push_back(os
);
665 this->attach_to_segment(os
, flags
);
670 // Attach an allocated output section to a segment.
673 Layout::attach_to_segment(Output_section
* os
, elfcpp::Elf_Xword flags
)
675 gold_assert((flags
& elfcpp::SHF_ALLOC
) != 0);
677 if (parameters
->options().relocatable())
680 // If we have a SECTIONS clause, we can't handle the attachment to
681 // segments until after we've seen all the sections.
682 if (this->script_options_
->saw_sections_clause())
685 gold_assert(!this->script_options_
->saw_phdrs_clause());
687 // This output section goes into a PT_LOAD segment.
689 elfcpp::Elf_Word seg_flags
= Layout::section_flags_to_segment(flags
);
691 // In general the only thing we really care about for PT_LOAD
692 // segments is whether or not they are writable, so that is how we
693 // search for them. People who need segments sorted on some other
694 // basis will have to use a linker script.
696 Segment_list::const_iterator p
;
697 for (p
= this->segment_list_
.begin();
698 p
!= this->segment_list_
.end();
701 if ((*p
)->type() == elfcpp::PT_LOAD
702 && ((*p
)->flags() & elfcpp::PF_W
) == (seg_flags
& elfcpp::PF_W
))
704 // If -Tbss was specified, we need to separate the data
706 if (this->options_
.user_set_Tbss())
708 if ((os
->type() == elfcpp::SHT_NOBITS
)
709 == (*p
)->has_any_data_sections())
713 (*p
)->add_output_section(os
, seg_flags
);
718 if (p
== this->segment_list_
.end())
720 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_LOAD
,
722 oseg
->add_output_section(os
, seg_flags
);
725 // If we see a loadable SHT_NOTE section, we create a PT_NOTE
727 if (os
->type() == elfcpp::SHT_NOTE
)
729 // See if we already have an equivalent PT_NOTE segment.
730 for (p
= this->segment_list_
.begin();
731 p
!= segment_list_
.end();
734 if ((*p
)->type() == elfcpp::PT_NOTE
735 && (((*p
)->flags() & elfcpp::PF_W
)
736 == (seg_flags
& elfcpp::PF_W
)))
738 (*p
)->add_output_section(os
, seg_flags
);
743 if (p
== this->segment_list_
.end())
745 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_NOTE
,
747 oseg
->add_output_section(os
, seg_flags
);
751 // If we see a loadable SHF_TLS section, we create a PT_TLS
752 // segment. There can only be one such segment.
753 if ((flags
& elfcpp::SHF_TLS
) != 0)
755 if (this->tls_segment_
== NULL
)
756 this->tls_segment_
= this->make_output_segment(elfcpp::PT_TLS
,
758 this->tls_segment_
->add_output_section(os
, seg_flags
);
762 // Make an output section for a script.
765 Layout::make_output_section_for_script(const char* name
)
767 name
= this->namepool_
.add(name
, false, NULL
);
768 Output_section
* os
= this->make_output_section(name
, elfcpp::SHT_PROGBITS
,
770 os
->set_found_in_sections_clause();
774 // We have to move an existing output section from the unallocated
775 // list to the allocated list.
778 Layout::allocate_output_section(Output_section
* os
, elfcpp::Elf_Xword flags
)
780 os
->reset_address_and_file_offset();
782 Section_list::iterator p
= std::find(this->unattached_section_list_
.begin(),
783 this->unattached_section_list_
.end(),
785 gold_assert(p
!= this->unattached_section_list_
.end());
786 this->unattached_section_list_
.erase(p
);
788 this->attach_to_segment(os
, flags
);
791 // We have to move an existing output section from the read-only
792 // segment to the writable segment.
795 Layout::write_enable_output_section(Output_section
* os
,
796 elfcpp::Elf_Xword flags
)
798 gold_assert((os
->flags() & elfcpp::SHF_WRITE
) == 0);
799 gold_assert(os
->type() == elfcpp::SHT_PROGBITS
);
800 gold_assert((flags
& elfcpp::SHF_WRITE
) != 0);
801 gold_assert((flags
& elfcpp::SHF_ALLOC
) != 0);
803 if (parameters
->options().relocatable())
806 if (this->script_options_
->saw_sections_clause())
809 Segment_list::iterator p
;
810 for (p
= this->segment_list_
.begin();
811 p
!= this->segment_list_
.end();
814 if ((*p
)->type() == elfcpp::PT_LOAD
815 && ((*p
)->flags() & elfcpp::PF_W
) == 0)
817 (*p
)->remove_output_section(os
);
821 gold_assert(p
!= this->segment_list_
.end());
823 this->attach_to_segment(os
, flags
);
826 // Return the number of segments we expect to see.
829 Layout::expected_segment_count() const
831 size_t ret
= this->segment_list_
.size();
833 // If we didn't see a SECTIONS clause in a linker script, we should
834 // already have the complete list of segments. Otherwise we ask the
835 // SECTIONS clause how many segments it expects, and add in the ones
836 // we already have (PT_GNU_STACK, PT_GNU_EH_FRAME, etc.)
838 if (!this->script_options_
->saw_sections_clause())
842 const Script_sections
* ss
= this->script_options_
->script_sections();
843 return ret
+ ss
->expected_segment_count(this);
847 // Handle the .note.GNU-stack section at layout time. SEEN_GNU_STACK
848 // is whether we saw a .note.GNU-stack section in the object file.
849 // GNU_STACK_FLAGS is the section flags. The flags give the
850 // protection required for stack memory. We record this in an
851 // executable as a PT_GNU_STACK segment. If an object file does not
852 // have a .note.GNU-stack segment, we must assume that it is an old
853 // object. On some targets that will force an executable stack.
856 Layout::layout_gnu_stack(bool seen_gnu_stack
, uint64_t gnu_stack_flags
)
859 this->input_without_gnu_stack_note_
= true;
862 this->input_with_gnu_stack_note_
= true;
863 if ((gnu_stack_flags
& elfcpp::SHF_EXECINSTR
) != 0)
864 this->input_requires_executable_stack_
= true;
868 // Create the dynamic sections which are needed before we read the
872 Layout::create_initial_dynamic_sections(Symbol_table
* symtab
)
874 if (parameters
->doing_static_link())
877 this->dynamic_section_
= this->choose_output_section(NULL
, ".dynamic",
880 | elfcpp::SHF_WRITE
),
883 symtab
->define_in_output_data("_DYNAMIC", NULL
, this->dynamic_section_
, 0, 0,
884 elfcpp::STT_OBJECT
, elfcpp::STB_LOCAL
,
885 elfcpp::STV_HIDDEN
, 0, false, false);
887 this->dynamic_data_
= new Output_data_dynamic(&this->dynpool_
);
889 this->dynamic_section_
->add_output_section_data(this->dynamic_data_
);
892 // For each output section whose name can be represented as C symbol,
893 // define __start and __stop symbols for the section. This is a GNU
897 Layout::define_section_symbols(Symbol_table
* symtab
)
899 for (Section_list::const_iterator p
= this->section_list_
.begin();
900 p
!= this->section_list_
.end();
903 const char* const name
= (*p
)->name();
904 if (name
[strspn(name
,
906 "ABCDEFGHIJKLMNOPWRSTUVWXYZ"
907 "abcdefghijklmnopqrstuvwxyz"
911 const std::string
name_string(name
);
912 const std::string
start_name("__start_" + name_string
);
913 const std::string
stop_name("__stop_" + name_string
);
915 symtab
->define_in_output_data(start_name
.c_str(),
924 false, // offset_is_from_end
925 true); // only_if_ref
927 symtab
->define_in_output_data(stop_name
.c_str(),
936 true, // offset_is_from_end
937 true); // only_if_ref
942 // Define symbols for group signatures.
945 Layout::define_group_signatures(Symbol_table
* symtab
)
947 for (Group_signatures::iterator p
= this->group_signatures_
.begin();
948 p
!= this->group_signatures_
.end();
951 Symbol
* sym
= symtab
->lookup(p
->signature
, NULL
);
953 p
->section
->set_info_symndx(sym
);
956 // Force the name of the group section to the group
957 // signature, and use the group's section symbol as the
959 if (strcmp(p
->section
->name(), p
->signature
) != 0)
961 const char* name
= this->namepool_
.add(p
->signature
,
963 p
->section
->set_name(name
);
965 p
->section
->set_needs_symtab_index();
966 p
->section
->set_info_section_symndx(p
->section
);
970 this->group_signatures_
.clear();
973 // Find the first read-only PT_LOAD segment, creating one if
977 Layout::find_first_load_seg()
979 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
980 p
!= this->segment_list_
.end();
983 if ((*p
)->type() == elfcpp::PT_LOAD
984 && ((*p
)->flags() & elfcpp::PF_R
) != 0
985 && ((*p
)->flags() & elfcpp::PF_W
) == 0)
989 gold_assert(!this->script_options_
->saw_phdrs_clause());
991 Output_segment
* load_seg
= this->make_output_segment(elfcpp::PT_LOAD
,
996 // Finalize the layout. When this is called, we have created all the
997 // output sections and all the output segments which are based on
998 // input sections. We have several things to do, and we have to do
999 // them in the right order, so that we get the right results correctly
1002 // 1) Finalize the list of output segments and create the segment
1005 // 2) Finalize the dynamic symbol table and associated sections.
1007 // 3) Determine the final file offset of all the output segments.
1009 // 4) Determine the final file offset of all the SHF_ALLOC output
1012 // 5) Create the symbol table sections and the section name table
1015 // 6) Finalize the symbol table: set symbol values to their final
1016 // value and make a final determination of which symbols are going
1017 // into the output symbol table.
1019 // 7) Create the section table header.
1021 // 8) Determine the final file offset of all the output sections which
1022 // are not SHF_ALLOC, including the section table header.
1024 // 9) Finalize the ELF file header.
1026 // This function returns the size of the output file.
1029 Layout::finalize(const Input_objects
* input_objects
, Symbol_table
* symtab
,
1030 Target
* target
, const Task
* task
)
1032 target
->finalize_sections(this);
1034 this->count_local_symbols(task
, input_objects
);
1036 this->create_gold_note();
1037 this->create_executable_stack_info(target
);
1039 Output_segment
* phdr_seg
= NULL
;
1040 if (!parameters
->options().relocatable() && !parameters
->doing_static_link())
1042 // There was a dynamic object in the link. We need to create
1043 // some information for the dynamic linker.
1045 // Create the PT_PHDR segment which will hold the program
1047 if (!this->script_options_
->saw_phdrs_clause())
1048 phdr_seg
= this->make_output_segment(elfcpp::PT_PHDR
, elfcpp::PF_R
);
1050 // Create the dynamic symbol table, including the hash table.
1051 Output_section
* dynstr
;
1052 std::vector
<Symbol
*> dynamic_symbols
;
1053 unsigned int local_dynamic_count
;
1054 Versions
versions(*this->script_options()->version_script_info(),
1056 this->create_dynamic_symtab(input_objects
, symtab
, &dynstr
,
1057 &local_dynamic_count
, &dynamic_symbols
,
1060 // Create the .interp section to hold the name of the
1061 // interpreter, and put it in a PT_INTERP segment.
1062 if (!parameters
->options().shared())
1063 this->create_interp(target
);
1065 // Finish the .dynamic section to hold the dynamic data, and put
1066 // it in a PT_DYNAMIC segment.
1067 this->finish_dynamic_section(input_objects
, symtab
);
1069 // We should have added everything we need to the dynamic string
1071 this->dynpool_
.set_string_offsets();
1073 // Create the version sections. We can't do this until the
1074 // dynamic string table is complete.
1075 this->create_version_sections(&versions
, symtab
, local_dynamic_count
,
1076 dynamic_symbols
, dynstr
);
1079 // If there is a SECTIONS clause, put all the input sections into
1080 // the required order.
1081 Output_segment
* load_seg
;
1082 if (this->script_options_
->saw_sections_clause())
1083 load_seg
= this->set_section_addresses_from_script(symtab
);
1084 else if (parameters
->options().relocatable())
1087 load_seg
= this->find_first_load_seg();
1089 if (this->options_
.oformat_enum() != General_options::OBJECT_FORMAT_ELF
)
1092 gold_assert(phdr_seg
== NULL
|| load_seg
!= NULL
);
1094 // Lay out the segment headers.
1095 Output_segment_headers
* segment_headers
;
1096 if (parameters
->options().relocatable())
1097 segment_headers
= NULL
;
1100 segment_headers
= new Output_segment_headers(this->segment_list_
);
1101 if (load_seg
!= NULL
)
1102 load_seg
->add_initial_output_data(segment_headers
);
1103 if (phdr_seg
!= NULL
)
1104 phdr_seg
->add_initial_output_data(segment_headers
);
1107 // Lay out the file header.
1108 Output_file_header
* file_header
;
1109 file_header
= new Output_file_header(target
, symtab
, segment_headers
,
1110 this->options_
.entry());
1111 if (load_seg
!= NULL
)
1112 load_seg
->add_initial_output_data(file_header
);
1114 this->special_output_list_
.push_back(file_header
);
1115 if (segment_headers
!= NULL
)
1116 this->special_output_list_
.push_back(segment_headers
);
1118 if (this->script_options_
->saw_phdrs_clause()
1119 && !parameters
->options().relocatable())
1121 // Support use of FILEHDRS and PHDRS attachments in a PHDRS
1122 // clause in a linker script.
1123 Script_sections
* ss
= this->script_options_
->script_sections();
1124 ss
->put_headers_in_phdrs(file_header
, segment_headers
);
1127 // We set the output section indexes in set_segment_offsets and
1128 // set_section_indexes.
1129 unsigned int shndx
= 1;
1131 // Set the file offsets of all the segments, and all the sections
1134 if (!parameters
->options().relocatable())
1135 off
= this->set_segment_offsets(target
, load_seg
, &shndx
);
1137 off
= this->set_relocatable_section_offsets(file_header
, &shndx
);
1139 // Set the file offsets of all the non-data sections we've seen so
1140 // far which don't have to wait for the input sections. We need
1141 // this in order to finalize local symbols in non-allocated
1143 off
= this->set_section_offsets(off
, BEFORE_INPUT_SECTIONS_PASS
);
1145 // Create the symbol table sections.
1146 this->create_symtab_sections(input_objects
, symtab
, &off
);
1147 if (!parameters
->doing_static_link())
1148 this->assign_local_dynsym_offsets(input_objects
);
1150 // Process any symbol assignments from a linker script. This must
1151 // be called after the symbol table has been finalized.
1152 this->script_options_
->finalize_symbols(symtab
, this);
1154 // Create the .shstrtab section.
1155 Output_section
* shstrtab_section
= this->create_shstrtab();
1157 // Set the file offsets of the rest of the non-data sections which
1158 // don't have to wait for the input sections.
1159 off
= this->set_section_offsets(off
, BEFORE_INPUT_SECTIONS_PASS
);
1161 // Now that all sections have been created, set the section indexes.
1162 shndx
= this->set_section_indexes(shndx
);
1164 // Create the section table header.
1165 this->create_shdrs(&off
);
1167 // If there are no sections which require postprocessing, we can
1168 // handle the section names now, and avoid a resize later.
1169 if (!this->any_postprocessing_sections_
)
1170 off
= this->set_section_offsets(off
,
1171 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
);
1173 file_header
->set_section_info(this->section_headers_
, shstrtab_section
);
1175 // Now we know exactly where everything goes in the output file
1176 // (except for non-allocated sections which require postprocessing).
1177 Output_data::layout_complete();
1179 this->output_file_size_
= off
;
1184 // Create a .note section for an executable or shared library. This
1185 // records the version of gold used to create the binary.
1188 Layout::create_gold_note()
1190 if (parameters
->options().relocatable())
1193 // Authorities all agree that the values in a .note field should
1194 // be aligned on 4-byte boundaries for 32-bit binaries. However,
1195 // they differ on what the alignment is for 64-bit binaries.
1196 // The GABI says unambiguously they take 8-byte alignment:
1197 // http://sco.com/developers/gabi/latest/ch5.pheader.html#note_section
1198 // Other documentation says alignment should always be 4 bytes:
1199 // http://www.netbsd.org/docs/kernel/elf-notes.html#note-format
1200 // GNU ld and GNU readelf both support the latter (at least as of
1201 // version 2.16.91), and glibc always generates the latter for
1202 // .note.ABI-tag (as of version 1.6), so that's the one we go with
1204 #ifdef GABI_FORMAT_FOR_DOTNOTE_SECTION // This is not defined by default.
1205 const int size
= parameters
->target().get_size();
1207 const int size
= 32;
1210 // The contents of the .note section.
1211 const char* name
= "GNU";
1212 std::string
desc(std::string("gold ") + gold::get_version_string());
1213 size_t namesz
= strlen(name
) + 1;
1214 size_t aligned_namesz
= align_address(namesz
, size
/ 8);
1215 size_t descsz
= desc
.length() + 1;
1216 size_t aligned_descsz
= align_address(descsz
, size
/ 8);
1217 const int note_type
= 4;
1219 size_t notesz
= 3 * (size
/ 8) + aligned_namesz
+ aligned_descsz
;
1221 unsigned char buffer
[128];
1222 gold_assert(sizeof buffer
>= notesz
);
1223 memset(buffer
, 0, notesz
);
1225 bool is_big_endian
= parameters
->target().is_big_endian();
1231 elfcpp::Swap
<32, false>::writeval(buffer
, namesz
);
1232 elfcpp::Swap
<32, false>::writeval(buffer
+ 4, descsz
);
1233 elfcpp::Swap
<32, false>::writeval(buffer
+ 8, note_type
);
1237 elfcpp::Swap
<32, true>::writeval(buffer
, namesz
);
1238 elfcpp::Swap
<32, true>::writeval(buffer
+ 4, descsz
);
1239 elfcpp::Swap
<32, true>::writeval(buffer
+ 8, note_type
);
1242 else if (size
== 64)
1246 elfcpp::Swap
<64, false>::writeval(buffer
, namesz
);
1247 elfcpp::Swap
<64, false>::writeval(buffer
+ 8, descsz
);
1248 elfcpp::Swap
<64, false>::writeval(buffer
+ 16, note_type
);
1252 elfcpp::Swap
<64, true>::writeval(buffer
, namesz
);
1253 elfcpp::Swap
<64, true>::writeval(buffer
+ 8, descsz
);
1254 elfcpp::Swap
<64, true>::writeval(buffer
+ 16, note_type
);
1260 memcpy(buffer
+ 3 * (size
/ 8), name
, namesz
);
1261 memcpy(buffer
+ 3 * (size
/ 8) + aligned_namesz
, desc
.data(), descsz
);
1263 const char* note_name
= this->namepool_
.add(".note", false, NULL
);
1264 Output_section
* os
= this->make_output_section(note_name
,
1267 Output_section_data
* posd
= new Output_data_const(buffer
, notesz
,
1269 os
->add_output_section_data(posd
);
1272 // Record whether the stack should be executable. This can be set
1273 // from the command line using the -z execstack or -z noexecstack
1274 // options. Otherwise, if any input file has a .note.GNU-stack
1275 // section with the SHF_EXECINSTR flag set, the stack should be
1276 // executable. Otherwise, if at least one input file a
1277 // .note.GNU-stack section, and some input file has no .note.GNU-stack
1278 // section, we use the target default for whether the stack should be
1279 // executable. Otherwise, we don't generate a stack note. When
1280 // generating a object file, we create a .note.GNU-stack section with
1281 // the appropriate marking. When generating an executable or shared
1282 // library, we create a PT_GNU_STACK segment.
1285 Layout::create_executable_stack_info(const Target
* target
)
1287 bool is_stack_executable
;
1288 if (this->options_
.is_execstack_set())
1289 is_stack_executable
= this->options_
.is_stack_executable();
1290 else if (!this->input_with_gnu_stack_note_
)
1294 if (this->input_requires_executable_stack_
)
1295 is_stack_executable
= true;
1296 else if (this->input_without_gnu_stack_note_
)
1297 is_stack_executable
= target
->is_default_stack_executable();
1299 is_stack_executable
= false;
1302 if (parameters
->options().relocatable())
1304 const char* name
= this->namepool_
.add(".note.GNU-stack", false, NULL
);
1305 elfcpp::Elf_Xword flags
= 0;
1306 if (is_stack_executable
)
1307 flags
|= elfcpp::SHF_EXECINSTR
;
1308 this->make_output_section(name
, elfcpp::SHT_PROGBITS
, flags
);
1312 if (this->script_options_
->saw_phdrs_clause())
1314 int flags
= elfcpp::PF_R
| elfcpp::PF_W
;
1315 if (is_stack_executable
)
1316 flags
|= elfcpp::PF_X
;
1317 this->make_output_segment(elfcpp::PT_GNU_STACK
, flags
);
1321 // Return whether SEG1 should be before SEG2 in the output file. This
1322 // is based entirely on the segment type and flags. When this is
1323 // called the segment addresses has normally not yet been set.
1326 Layout::segment_precedes(const Output_segment
* seg1
,
1327 const Output_segment
* seg2
)
1329 elfcpp::Elf_Word type1
= seg1
->type();
1330 elfcpp::Elf_Word type2
= seg2
->type();
1332 // The single PT_PHDR segment is required to precede any loadable
1333 // segment. We simply make it always first.
1334 if (type1
== elfcpp::PT_PHDR
)
1336 gold_assert(type2
!= elfcpp::PT_PHDR
);
1339 if (type2
== elfcpp::PT_PHDR
)
1342 // The single PT_INTERP segment is required to precede any loadable
1343 // segment. We simply make it always second.
1344 if (type1
== elfcpp::PT_INTERP
)
1346 gold_assert(type2
!= elfcpp::PT_INTERP
);
1349 if (type2
== elfcpp::PT_INTERP
)
1352 // We then put PT_LOAD segments before any other segments.
1353 if (type1
== elfcpp::PT_LOAD
&& type2
!= elfcpp::PT_LOAD
)
1355 if (type2
== elfcpp::PT_LOAD
&& type1
!= elfcpp::PT_LOAD
)
1358 // We put the PT_TLS segment last, because that is where the dynamic
1359 // linker expects to find it (this is just for efficiency; other
1360 // positions would also work correctly).
1361 if (type1
== elfcpp::PT_TLS
&& type2
!= elfcpp::PT_TLS
)
1363 if (type2
== elfcpp::PT_TLS
&& type1
!= elfcpp::PT_TLS
)
1366 const elfcpp::Elf_Word flags1
= seg1
->flags();
1367 const elfcpp::Elf_Word flags2
= seg2
->flags();
1369 // The order of non-PT_LOAD segments is unimportant. We simply sort
1370 // by the numeric segment type and flags values. There should not
1371 // be more than one segment with the same type and flags.
1372 if (type1
!= elfcpp::PT_LOAD
)
1375 return type1
< type2
;
1376 gold_assert(flags1
!= flags2
);
1377 return flags1
< flags2
;
1380 // If the addresses are set already, sort by load address.
1381 if (seg1
->are_addresses_set())
1383 if (!seg2
->are_addresses_set())
1386 unsigned int section_count1
= seg1
->output_section_count();
1387 unsigned int section_count2
= seg2
->output_section_count();
1388 if (section_count1
== 0 && section_count2
> 0)
1390 if (section_count1
> 0 && section_count2
== 0)
1393 uint64_t paddr1
= seg1
->first_section_load_address();
1394 uint64_t paddr2
= seg2
->first_section_load_address();
1395 if (paddr1
!= paddr2
)
1396 return paddr1
< paddr2
;
1398 else if (seg2
->are_addresses_set())
1401 // We sort PT_LOAD segments based on the flags. Readonly segments
1402 // come before writable segments. Then writable segments with data
1403 // come before writable segments without data. Then executable
1404 // segments come before non-executable segments. Then the unlikely
1405 // case of a non-readable segment comes before the normal case of a
1406 // readable segment. If there are multiple segments with the same
1407 // type and flags, we require that the address be set, and we sort
1408 // by virtual address and then physical address.
1409 if ((flags1
& elfcpp::PF_W
) != (flags2
& elfcpp::PF_W
))
1410 return (flags1
& elfcpp::PF_W
) == 0;
1411 if ((flags1
& elfcpp::PF_W
) != 0
1412 && seg1
->has_any_data_sections() != seg2
->has_any_data_sections())
1413 return seg1
->has_any_data_sections();
1414 if ((flags1
& elfcpp::PF_X
) != (flags2
& elfcpp::PF_X
))
1415 return (flags1
& elfcpp::PF_X
) != 0;
1416 if ((flags1
& elfcpp::PF_R
) != (flags2
& elfcpp::PF_R
))
1417 return (flags1
& elfcpp::PF_R
) == 0;
1419 // We shouldn't get here--we shouldn't create segments which we
1420 // can't distinguish.
1424 // Set the file offsets of all the segments, and all the sections they
1425 // contain. They have all been created. LOAD_SEG must be be laid out
1426 // first. Return the offset of the data to follow.
1429 Layout::set_segment_offsets(const Target
* target
, Output_segment
* load_seg
,
1430 unsigned int *pshndx
)
1432 // Sort them into the final order.
1433 std::sort(this->segment_list_
.begin(), this->segment_list_
.end(),
1434 Layout::Compare_segments());
1436 // Find the PT_LOAD segments, and set their addresses and offsets
1437 // and their section's addresses and offsets.
1439 if (this->options_
.user_set_Ttext())
1440 addr
= this->options_
.Ttext();
1441 else if (parameters
->options().shared())
1444 addr
= target
->default_text_segment_address();
1447 // If LOAD_SEG is NULL, then the file header and segment headers
1448 // will not be loadable. But they still need to be at offset 0 in
1449 // the file. Set their offsets now.
1450 if (load_seg
== NULL
)
1452 for (Data_list::iterator p
= this->special_output_list_
.begin();
1453 p
!= this->special_output_list_
.end();
1456 off
= align_address(off
, (*p
)->addralign());
1457 (*p
)->set_address_and_file_offset(0, off
);
1458 off
+= (*p
)->data_size();
1462 bool was_readonly
= false;
1463 for (Segment_list::iterator p
= this->segment_list_
.begin();
1464 p
!= this->segment_list_
.end();
1467 if ((*p
)->type() == elfcpp::PT_LOAD
)
1469 if (load_seg
!= NULL
&& load_seg
!= *p
)
1473 bool are_addresses_set
= (*p
)->are_addresses_set();
1474 if (are_addresses_set
)
1476 // When it comes to setting file offsets, we care about
1477 // the physical address.
1478 addr
= (*p
)->paddr();
1480 else if (this->options_
.user_set_Tdata()
1481 && ((*p
)->flags() & elfcpp::PF_W
) != 0
1482 && (!this->options_
.user_set_Tbss()
1483 || (*p
)->has_any_data_sections()))
1485 addr
= this->options_
.Tdata();
1486 are_addresses_set
= true;
1488 else if (this->options_
.user_set_Tbss()
1489 && ((*p
)->flags() & elfcpp::PF_W
) != 0
1490 && !(*p
)->has_any_data_sections())
1492 addr
= this->options_
.Tbss();
1493 are_addresses_set
= true;
1496 uint64_t orig_addr
= addr
;
1497 uint64_t orig_off
= off
;
1499 uint64_t aligned_addr
= 0;
1500 uint64_t abi_pagesize
= target
->abi_pagesize();
1502 // FIXME: This should depend on the -n and -N options.
1503 (*p
)->set_minimum_p_align(target
->common_pagesize());
1505 if (are_addresses_set
)
1507 // Adjust the file offset to the same address modulo the
1509 uint64_t unsigned_off
= off
;
1510 uint64_t aligned_off
= ((unsigned_off
& ~(abi_pagesize
- 1))
1511 | (addr
& (abi_pagesize
- 1)));
1512 if (aligned_off
< unsigned_off
)
1513 aligned_off
+= abi_pagesize
;
1518 // If the last segment was readonly, and this one is
1519 // not, then skip the address forward one page,
1520 // maintaining the same position within the page. This
1521 // lets us store both segments overlapping on a single
1522 // page in the file, but the loader will put them on
1523 // different pages in memory.
1525 addr
= align_address(addr
, (*p
)->maximum_alignment());
1526 aligned_addr
= addr
;
1528 if (was_readonly
&& ((*p
)->flags() & elfcpp::PF_W
) != 0)
1530 if ((addr
& (abi_pagesize
- 1)) != 0)
1531 addr
= addr
+ abi_pagesize
;
1534 off
= orig_off
+ ((addr
- orig_addr
) & (abi_pagesize
- 1));
1537 unsigned int shndx_hold
= *pshndx
;
1538 uint64_t new_addr
= (*p
)->set_section_addresses(false, addr
, &off
,
1541 // Now that we know the size of this segment, we may be able
1542 // to save a page in memory, at the cost of wasting some
1543 // file space, by instead aligning to the start of a new
1544 // page. Here we use the real machine page size rather than
1545 // the ABI mandated page size.
1547 if (!are_addresses_set
&& aligned_addr
!= addr
)
1549 uint64_t common_pagesize
= target
->common_pagesize();
1550 uint64_t first_off
= (common_pagesize
1552 & (common_pagesize
- 1)));
1553 uint64_t last_off
= new_addr
& (common_pagesize
- 1);
1556 && ((aligned_addr
& ~ (common_pagesize
- 1))
1557 != (new_addr
& ~ (common_pagesize
- 1)))
1558 && first_off
+ last_off
<= common_pagesize
)
1560 *pshndx
= shndx_hold
;
1561 addr
= align_address(aligned_addr
, common_pagesize
);
1562 addr
= align_address(addr
, (*p
)->maximum_alignment());
1563 off
= orig_off
+ ((addr
- orig_addr
) & (abi_pagesize
- 1));
1564 new_addr
= (*p
)->set_section_addresses(true, addr
, &off
,
1571 if (((*p
)->flags() & elfcpp::PF_W
) == 0)
1572 was_readonly
= true;
1576 // Handle the non-PT_LOAD segments, setting their offsets from their
1577 // section's offsets.
1578 for (Segment_list::iterator p
= this->segment_list_
.begin();
1579 p
!= this->segment_list_
.end();
1582 if ((*p
)->type() != elfcpp::PT_LOAD
)
1586 // Set the TLS offsets for each section in the PT_TLS segment.
1587 if (this->tls_segment_
!= NULL
)
1588 this->tls_segment_
->set_tls_offsets();
1593 // Set the offsets of all the allocated sections when doing a
1594 // relocatable link. This does the same jobs as set_segment_offsets,
1595 // only for a relocatable link.
1598 Layout::set_relocatable_section_offsets(Output_data
* file_header
,
1599 unsigned int *pshndx
)
1603 file_header
->set_address_and_file_offset(0, 0);
1604 off
+= file_header
->data_size();
1606 for (Section_list::iterator p
= this->section_list_
.begin();
1607 p
!= this->section_list_
.end();
1610 // We skip unallocated sections here, except that group sections
1611 // have to come first.
1612 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) == 0
1613 && (*p
)->type() != elfcpp::SHT_GROUP
)
1616 off
= align_address(off
, (*p
)->addralign());
1618 // The linker script might have set the address.
1619 if (!(*p
)->is_address_valid())
1620 (*p
)->set_address(0);
1621 (*p
)->set_file_offset(off
);
1622 (*p
)->finalize_data_size();
1623 off
+= (*p
)->data_size();
1625 (*p
)->set_out_shndx(*pshndx
);
1632 // Set the file offset of all the sections not associated with a
1636 Layout::set_section_offsets(off_t off
, Layout::Section_offset_pass pass
)
1638 for (Section_list::iterator p
= this->unattached_section_list_
.begin();
1639 p
!= this->unattached_section_list_
.end();
1642 // The symtab section is handled in create_symtab_sections.
1643 if (*p
== this->symtab_section_
)
1646 // If we've already set the data size, don't set it again.
1647 if ((*p
)->is_offset_valid() && (*p
)->is_data_size_valid())
1650 if (pass
== BEFORE_INPUT_SECTIONS_PASS
1651 && (*p
)->requires_postprocessing())
1653 (*p
)->create_postprocessing_buffer();
1654 this->any_postprocessing_sections_
= true;
1657 if (pass
== BEFORE_INPUT_SECTIONS_PASS
1658 && (*p
)->after_input_sections())
1660 else if (pass
== POSTPROCESSING_SECTIONS_PASS
1661 && (!(*p
)->after_input_sections()
1662 || (*p
)->type() == elfcpp::SHT_STRTAB
))
1664 else if (pass
== STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
1665 && (!(*p
)->after_input_sections()
1666 || (*p
)->type() != elfcpp::SHT_STRTAB
))
1669 off
= align_address(off
, (*p
)->addralign());
1670 (*p
)->set_file_offset(off
);
1671 (*p
)->finalize_data_size();
1672 off
+= (*p
)->data_size();
1674 // At this point the name must be set.
1675 if (pass
!= STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
)
1676 this->namepool_
.add((*p
)->name(), false, NULL
);
1681 // Set the section indexes of all the sections not associated with a
1685 Layout::set_section_indexes(unsigned int shndx
)
1687 const bool output_is_object
= parameters
->options().relocatable();
1688 for (Section_list::iterator p
= this->unattached_section_list_
.begin();
1689 p
!= this->unattached_section_list_
.end();
1692 // In a relocatable link, we already did group sections.
1693 if (output_is_object
1694 && (*p
)->type() == elfcpp::SHT_GROUP
)
1697 (*p
)->set_out_shndx(shndx
);
1703 // Set the section addresses according to the linker script. This is
1704 // only called when we see a SECTIONS clause. This returns the
1705 // program segment which should hold the file header and segment
1706 // headers, if any. It will return NULL if they should not be in a
1710 Layout::set_section_addresses_from_script(Symbol_table
* symtab
)
1712 Script_sections
* ss
= this->script_options_
->script_sections();
1713 gold_assert(ss
->saw_sections_clause());
1715 // Place each orphaned output section in the script.
1716 for (Section_list::iterator p
= this->section_list_
.begin();
1717 p
!= this->section_list_
.end();
1720 if (!(*p
)->found_in_sections_clause())
1721 ss
->place_orphan(*p
);
1724 return this->script_options_
->set_section_addresses(symtab
, this);
1727 // Count the local symbols in the regular symbol table and the dynamic
1728 // symbol table, and build the respective string pools.
1731 Layout::count_local_symbols(const Task
* task
,
1732 const Input_objects
* input_objects
)
1734 // First, figure out an upper bound on the number of symbols we'll
1735 // be inserting into each pool. This helps us create the pools with
1736 // the right size, to avoid unnecessary hashtable resizing.
1737 unsigned int symbol_count
= 0;
1738 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
1739 p
!= input_objects
->relobj_end();
1741 symbol_count
+= (*p
)->local_symbol_count();
1743 // Go from "upper bound" to "estimate." We overcount for two
1744 // reasons: we double-count symbols that occur in more than one
1745 // object file, and we count symbols that are dropped from the
1746 // output. Add it all together and assume we overcount by 100%.
1749 // We assume all symbols will go into both the sympool and dynpool.
1750 this->sympool_
.reserve(symbol_count
);
1751 this->dynpool_
.reserve(symbol_count
);
1753 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
1754 p
!= input_objects
->relobj_end();
1757 Task_lock_obj
<Object
> tlo(task
, *p
);
1758 (*p
)->count_local_symbols(&this->sympool_
, &this->dynpool_
);
1762 // Create the symbol table sections. Here we also set the final
1763 // values of the symbols. At this point all the loadable sections are
1767 Layout::create_symtab_sections(const Input_objects
* input_objects
,
1768 Symbol_table
* symtab
,
1773 if (parameters
->target().get_size() == 32)
1775 symsize
= elfcpp::Elf_sizes
<32>::sym_size
;
1778 else if (parameters
->target().get_size() == 64)
1780 symsize
= elfcpp::Elf_sizes
<64>::sym_size
;
1787 off
= align_address(off
, align
);
1788 off_t startoff
= off
;
1790 // Save space for the dummy symbol at the start of the section. We
1791 // never bother to write this out--it will just be left as zero.
1793 unsigned int local_symbol_index
= 1;
1795 // Add STT_SECTION symbols for each Output section which needs one.
1796 for (Section_list::iterator p
= this->section_list_
.begin();
1797 p
!= this->section_list_
.end();
1800 if (!(*p
)->needs_symtab_index())
1801 (*p
)->set_symtab_index(-1U);
1804 (*p
)->set_symtab_index(local_symbol_index
);
1805 ++local_symbol_index
;
1810 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
1811 p
!= input_objects
->relobj_end();
1814 unsigned int index
= (*p
)->finalize_local_symbols(local_symbol_index
,
1816 off
+= (index
- local_symbol_index
) * symsize
;
1817 local_symbol_index
= index
;
1820 unsigned int local_symcount
= local_symbol_index
;
1821 gold_assert(local_symcount
* symsize
== off
- startoff
);
1824 size_t dyn_global_index
;
1826 if (this->dynsym_section_
== NULL
)
1829 dyn_global_index
= 0;
1834 dyn_global_index
= this->dynsym_section_
->info();
1835 off_t locsize
= dyn_global_index
* this->dynsym_section_
->entsize();
1836 dynoff
= this->dynsym_section_
->offset() + locsize
;
1837 dyncount
= (this->dynsym_section_
->data_size() - locsize
) / symsize
;
1838 gold_assert(static_cast<off_t
>(dyncount
* symsize
)
1839 == this->dynsym_section_
->data_size() - locsize
);
1842 off
= symtab
->finalize(off
, dynoff
, dyn_global_index
, dyncount
,
1843 &this->sympool_
, &local_symcount
);
1845 if (!parameters
->options().strip_all())
1847 this->sympool_
.set_string_offsets();
1849 const char* symtab_name
= this->namepool_
.add(".symtab", false, NULL
);
1850 Output_section
* osymtab
= this->make_output_section(symtab_name
,
1853 this->symtab_section_
= osymtab
;
1855 Output_section_data
* pos
= new Output_data_fixed_space(off
- startoff
,
1857 osymtab
->add_output_section_data(pos
);
1859 const char* strtab_name
= this->namepool_
.add(".strtab", false, NULL
);
1860 Output_section
* ostrtab
= this->make_output_section(strtab_name
,
1864 Output_section_data
* pstr
= new Output_data_strtab(&this->sympool_
);
1865 ostrtab
->add_output_section_data(pstr
);
1867 osymtab
->set_file_offset(startoff
);
1868 osymtab
->finalize_data_size();
1869 osymtab
->set_link_section(ostrtab
);
1870 osymtab
->set_info(local_symcount
);
1871 osymtab
->set_entsize(symsize
);
1877 // Create the .shstrtab section, which holds the names of the
1878 // sections. At the time this is called, we have created all the
1879 // output sections except .shstrtab itself.
1882 Layout::create_shstrtab()
1884 // FIXME: We don't need to create a .shstrtab section if we are
1885 // stripping everything.
1887 const char* name
= this->namepool_
.add(".shstrtab", false, NULL
);
1889 Output_section
* os
= this->make_output_section(name
, elfcpp::SHT_STRTAB
, 0);
1891 // We can't write out this section until we've set all the section
1892 // names, and we don't set the names of compressed output sections
1893 // until relocations are complete.
1894 os
->set_after_input_sections();
1896 Output_section_data
* posd
= new Output_data_strtab(&this->namepool_
);
1897 os
->add_output_section_data(posd
);
1902 // Create the section headers. SIZE is 32 or 64. OFF is the file
1906 Layout::create_shdrs(off_t
* poff
)
1908 Output_section_headers
* oshdrs
;
1909 oshdrs
= new Output_section_headers(this,
1910 &this->segment_list_
,
1911 &this->section_list_
,
1912 &this->unattached_section_list_
,
1914 off_t off
= align_address(*poff
, oshdrs
->addralign());
1915 oshdrs
->set_address_and_file_offset(0, off
);
1916 off
+= oshdrs
->data_size();
1918 this->section_headers_
= oshdrs
;
1921 // Create the dynamic symbol table.
1924 Layout::create_dynamic_symtab(const Input_objects
* input_objects
,
1925 Symbol_table
* symtab
,
1926 Output_section
**pdynstr
,
1927 unsigned int* plocal_dynamic_count
,
1928 std::vector
<Symbol
*>* pdynamic_symbols
,
1929 Versions
* pversions
)
1931 // Count all the symbols in the dynamic symbol table, and set the
1932 // dynamic symbol indexes.
1934 // Skip symbol 0, which is always all zeroes.
1935 unsigned int index
= 1;
1937 // Add STT_SECTION symbols for each Output section which needs one.
1938 for (Section_list::iterator p
= this->section_list_
.begin();
1939 p
!= this->section_list_
.end();
1942 if (!(*p
)->needs_dynsym_index())
1943 (*p
)->set_dynsym_index(-1U);
1946 (*p
)->set_dynsym_index(index
);
1951 // Count the local symbols that need to go in the dynamic symbol table,
1952 // and set the dynamic symbol indexes.
1953 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
1954 p
!= input_objects
->relobj_end();
1957 unsigned int new_index
= (*p
)->set_local_dynsym_indexes(index
);
1961 unsigned int local_symcount
= index
;
1962 *plocal_dynamic_count
= local_symcount
;
1964 // FIXME: We have to tell set_dynsym_indexes whether the
1965 // -E/--export-dynamic option was used.
1966 index
= symtab
->set_dynsym_indexes(index
, pdynamic_symbols
,
1967 &this->dynpool_
, pversions
);
1971 const int size
= parameters
->target().get_size();
1974 symsize
= elfcpp::Elf_sizes
<32>::sym_size
;
1977 else if (size
== 64)
1979 symsize
= elfcpp::Elf_sizes
<64>::sym_size
;
1985 // Create the dynamic symbol table section.
1987 Output_section
* dynsym
= this->choose_output_section(NULL
, ".dynsym",
1992 Output_section_data
* odata
= new Output_data_fixed_space(index
* symsize
,
1994 dynsym
->add_output_section_data(odata
);
1996 dynsym
->set_info(local_symcount
);
1997 dynsym
->set_entsize(symsize
);
1998 dynsym
->set_addralign(align
);
2000 this->dynsym_section_
= dynsym
;
2002 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
2003 odyn
->add_section_address(elfcpp::DT_SYMTAB
, dynsym
);
2004 odyn
->add_constant(elfcpp::DT_SYMENT
, symsize
);
2006 // Create the dynamic string table section.
2008 Output_section
* dynstr
= this->choose_output_section(NULL
, ".dynstr",
2013 Output_section_data
* strdata
= new Output_data_strtab(&this->dynpool_
);
2014 dynstr
->add_output_section_data(strdata
);
2016 dynsym
->set_link_section(dynstr
);
2017 this->dynamic_section_
->set_link_section(dynstr
);
2019 odyn
->add_section_address(elfcpp::DT_STRTAB
, dynstr
);
2020 odyn
->add_section_size(elfcpp::DT_STRSZ
, dynstr
);
2024 // Create the hash tables.
2026 if (strcmp(parameters
->options().hash_style(), "sysv") == 0
2027 || strcmp(parameters
->options().hash_style(), "both") == 0)
2029 unsigned char* phash
;
2030 unsigned int hashlen
;
2031 Dynobj::create_elf_hash_table(*pdynamic_symbols
, local_symcount
,
2034 Output_section
* hashsec
= this->choose_output_section(NULL
, ".hash",
2039 Output_section_data
* hashdata
= new Output_data_const_buffer(phash
,
2042 hashsec
->add_output_section_data(hashdata
);
2044 hashsec
->set_link_section(dynsym
);
2045 hashsec
->set_entsize(4);
2047 odyn
->add_section_address(elfcpp::DT_HASH
, hashsec
);
2050 if (strcmp(parameters
->options().hash_style(), "gnu") == 0
2051 || strcmp(parameters
->options().hash_style(), "both") == 0)
2053 unsigned char* phash
;
2054 unsigned int hashlen
;
2055 Dynobj::create_gnu_hash_table(*pdynamic_symbols
, local_symcount
,
2058 Output_section
* hashsec
= this->choose_output_section(NULL
, ".gnu.hash",
2059 elfcpp::SHT_GNU_HASH
,
2063 Output_section_data
* hashdata
= new Output_data_const_buffer(phash
,
2066 hashsec
->add_output_section_data(hashdata
);
2068 hashsec
->set_link_section(dynsym
);
2069 hashsec
->set_entsize(4);
2071 odyn
->add_section_address(elfcpp::DT_GNU_HASH
, hashsec
);
2075 // Assign offsets to each local portion of the dynamic symbol table.
2078 Layout::assign_local_dynsym_offsets(const Input_objects
* input_objects
)
2080 Output_section
* dynsym
= this->dynsym_section_
;
2081 gold_assert(dynsym
!= NULL
);
2083 off_t off
= dynsym
->offset();
2085 // Skip the dummy symbol at the start of the section.
2086 off
+= dynsym
->entsize();
2088 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
2089 p
!= input_objects
->relobj_end();
2092 unsigned int count
= (*p
)->set_local_dynsym_offset(off
);
2093 off
+= count
* dynsym
->entsize();
2097 // Create the version sections.
2100 Layout::create_version_sections(const Versions
* versions
,
2101 const Symbol_table
* symtab
,
2102 unsigned int local_symcount
,
2103 const std::vector
<Symbol
*>& dynamic_symbols
,
2104 const Output_section
* dynstr
)
2106 if (!versions
->any_defs() && !versions
->any_needs())
2109 switch (parameters
->size_and_endianness())
2111 #ifdef HAVE_TARGET_32_LITTLE
2112 case Parameters::TARGET_32_LITTLE
:
2113 this->sized_create_version_sections
<32, false>(versions
, symtab
,
2115 dynamic_symbols
, dynstr
);
2118 #ifdef HAVE_TARGET_32_BIG
2119 case Parameters::TARGET_32_BIG
:
2120 this->sized_create_version_sections
<32, true>(versions
, symtab
,
2122 dynamic_symbols
, dynstr
);
2125 #ifdef HAVE_TARGET_64_LITTLE
2126 case Parameters::TARGET_64_LITTLE
:
2127 this->sized_create_version_sections
<64, false>(versions
, symtab
,
2129 dynamic_symbols
, dynstr
);
2132 #ifdef HAVE_TARGET_64_BIG
2133 case Parameters::TARGET_64_BIG
:
2134 this->sized_create_version_sections
<64, true>(versions
, symtab
,
2136 dynamic_symbols
, dynstr
);
2144 // Create the version sections, sized version.
2146 template<int size
, bool big_endian
>
2148 Layout::sized_create_version_sections(
2149 const Versions
* versions
,
2150 const Symbol_table
* symtab
,
2151 unsigned int local_symcount
,
2152 const std::vector
<Symbol
*>& dynamic_symbols
,
2153 const Output_section
* dynstr
)
2155 Output_section
* vsec
= this->choose_output_section(NULL
, ".gnu.version",
2156 elfcpp::SHT_GNU_versym
,
2160 unsigned char* vbuf
;
2162 versions
->symbol_section_contents
<size
, big_endian
>(symtab
, &this->dynpool_
,
2167 Output_section_data
* vdata
= new Output_data_const_buffer(vbuf
, vsize
, 2);
2169 vsec
->add_output_section_data(vdata
);
2170 vsec
->set_entsize(2);
2171 vsec
->set_link_section(this->dynsym_section_
);
2173 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
2174 odyn
->add_section_address(elfcpp::DT_VERSYM
, vsec
);
2176 if (versions
->any_defs())
2178 Output_section
* vdsec
;
2179 vdsec
= this->choose_output_section(NULL
, ".gnu.version_d",
2180 elfcpp::SHT_GNU_verdef
,
2184 unsigned char* vdbuf
;
2185 unsigned int vdsize
;
2186 unsigned int vdentries
;
2187 versions
->def_section_contents
<size
, big_endian
>(&this->dynpool_
, &vdbuf
,
2188 &vdsize
, &vdentries
);
2190 Output_section_data
* vddata
= new Output_data_const_buffer(vdbuf
,
2194 vdsec
->add_output_section_data(vddata
);
2195 vdsec
->set_link_section(dynstr
);
2196 vdsec
->set_info(vdentries
);
2198 odyn
->add_section_address(elfcpp::DT_VERDEF
, vdsec
);
2199 odyn
->add_constant(elfcpp::DT_VERDEFNUM
, vdentries
);
2202 if (versions
->any_needs())
2204 Output_section
* vnsec
;
2205 vnsec
= this->choose_output_section(NULL
, ".gnu.version_r",
2206 elfcpp::SHT_GNU_verneed
,
2210 unsigned char* vnbuf
;
2211 unsigned int vnsize
;
2212 unsigned int vnentries
;
2213 versions
->need_section_contents
<size
, big_endian
>(&this->dynpool_
,
2217 Output_section_data
* vndata
= new Output_data_const_buffer(vnbuf
,
2221 vnsec
->add_output_section_data(vndata
);
2222 vnsec
->set_link_section(dynstr
);
2223 vnsec
->set_info(vnentries
);
2225 odyn
->add_section_address(elfcpp::DT_VERNEED
, vnsec
);
2226 odyn
->add_constant(elfcpp::DT_VERNEEDNUM
, vnentries
);
2230 // Create the .interp section and PT_INTERP segment.
2233 Layout::create_interp(const Target
* target
)
2235 const char* interp
= this->options_
.dynamic_linker();
2238 interp
= target
->dynamic_linker();
2239 gold_assert(interp
!= NULL
);
2242 size_t len
= strlen(interp
) + 1;
2244 Output_section_data
* odata
= new Output_data_const(interp
, len
, 1);
2246 Output_section
* osec
= this->choose_output_section(NULL
, ".interp",
2247 elfcpp::SHT_PROGBITS
,
2250 osec
->add_output_section_data(odata
);
2252 if (!this->script_options_
->saw_phdrs_clause())
2254 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_INTERP
,
2256 oseg
->add_initial_output_section(osec
, elfcpp::PF_R
);
2260 // Finish the .dynamic section and PT_DYNAMIC segment.
2263 Layout::finish_dynamic_section(const Input_objects
* input_objects
,
2264 const Symbol_table
* symtab
)
2266 if (!this->script_options_
->saw_phdrs_clause())
2268 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_DYNAMIC
,
2271 oseg
->add_initial_output_section(this->dynamic_section_
,
2272 elfcpp::PF_R
| elfcpp::PF_W
);
2275 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
2277 for (Input_objects::Dynobj_iterator p
= input_objects
->dynobj_begin();
2278 p
!= input_objects
->dynobj_end();
2281 // FIXME: Handle --as-needed.
2282 odyn
->add_string(elfcpp::DT_NEEDED
, (*p
)->soname());
2285 if (parameters
->options().shared())
2287 const char* soname
= this->options_
.soname();
2289 odyn
->add_string(elfcpp::DT_SONAME
, soname
);
2292 // FIXME: Support --init and --fini.
2293 Symbol
* sym
= symtab
->lookup("_init");
2294 if (sym
!= NULL
&& sym
->is_defined() && !sym
->is_from_dynobj())
2295 odyn
->add_symbol(elfcpp::DT_INIT
, sym
);
2297 sym
= symtab
->lookup("_fini");
2298 if (sym
!= NULL
&& sym
->is_defined() && !sym
->is_from_dynobj())
2299 odyn
->add_symbol(elfcpp::DT_FINI
, sym
);
2301 // FIXME: Support DT_INIT_ARRAY and DT_FINI_ARRAY.
2303 // Add a DT_RPATH entry if needed.
2304 const General_options::Dir_list
& rpath(this->options_
.rpath());
2307 std::string rpath_val
;
2308 for (General_options::Dir_list::const_iterator p
= rpath
.begin();
2312 if (rpath_val
.empty())
2313 rpath_val
= p
->name();
2316 // Eliminate duplicates.
2317 General_options::Dir_list::const_iterator q
;
2318 for (q
= rpath
.begin(); q
!= p
; ++q
)
2319 if (q
->name() == p
->name())
2324 rpath_val
+= p
->name();
2329 odyn
->add_string(elfcpp::DT_RPATH
, rpath_val
);
2332 // Look for text segments that have dynamic relocations.
2333 bool have_textrel
= false;
2334 if (!this->script_options_
->saw_sections_clause())
2336 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
2337 p
!= this->segment_list_
.end();
2340 if (((*p
)->flags() & elfcpp::PF_W
) == 0
2341 && (*p
)->dynamic_reloc_count() > 0)
2343 have_textrel
= true;
2350 // We don't know the section -> segment mapping, so we are
2351 // conservative and just look for readonly sections with
2352 // relocations. If those sections wind up in writable segments,
2353 // then we have created an unnecessary DT_TEXTREL entry.
2354 for (Section_list::const_iterator p
= this->section_list_
.begin();
2355 p
!= this->section_list_
.end();
2358 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) != 0
2359 && ((*p
)->flags() & elfcpp::SHF_WRITE
) == 0
2360 && ((*p
)->dynamic_reloc_count() > 0))
2362 have_textrel
= true;
2368 // Add a DT_FLAGS entry. We add it even if no flags are set so that
2369 // post-link tools can easily modify these flags if desired.
2370 unsigned int flags
= 0;
2373 // Add a DT_TEXTREL for compatibility with older loaders.
2374 odyn
->add_constant(elfcpp::DT_TEXTREL
, 0);
2375 flags
|= elfcpp::DF_TEXTREL
;
2377 if (parameters
->options().shared() && this->has_static_tls())
2378 flags
|= elfcpp::DF_STATIC_TLS
;
2379 odyn
->add_constant(elfcpp::DT_FLAGS
, flags
);
2382 // The mapping of .gnu.linkonce section names to real section names.
2384 #define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 }
2385 const Layout::Linkonce_mapping
Layout::linkonce_mapping
[] =
2387 MAPPING_INIT("d.rel.ro", ".data.rel.ro"), // Must be before "d".
2388 MAPPING_INIT("t", ".text"),
2389 MAPPING_INIT("r", ".rodata"),
2390 MAPPING_INIT("d", ".data"),
2391 MAPPING_INIT("b", ".bss"),
2392 MAPPING_INIT("s", ".sdata"),
2393 MAPPING_INIT("sb", ".sbss"),
2394 MAPPING_INIT("s2", ".sdata2"),
2395 MAPPING_INIT("sb2", ".sbss2"),
2396 MAPPING_INIT("wi", ".debug_info"),
2397 MAPPING_INIT("td", ".tdata"),
2398 MAPPING_INIT("tb", ".tbss"),
2399 MAPPING_INIT("lr", ".lrodata"),
2400 MAPPING_INIT("l", ".ldata"),
2401 MAPPING_INIT("lb", ".lbss"),
2405 const int Layout::linkonce_mapping_count
=
2406 sizeof(Layout::linkonce_mapping
) / sizeof(Layout::linkonce_mapping
[0]);
2408 // Return the name of the output section to use for a .gnu.linkonce
2409 // section. This is based on the default ELF linker script of the old
2410 // GNU linker. For example, we map a name like ".gnu.linkonce.t.foo"
2411 // to ".text". Set *PLEN to the length of the name. *PLEN is
2412 // initialized to the length of NAME.
2415 Layout::linkonce_output_name(const char* name
, size_t *plen
)
2417 const char* s
= name
+ sizeof(".gnu.linkonce") - 1;
2421 const Linkonce_mapping
* plm
= linkonce_mapping
;
2422 for (int i
= 0; i
< linkonce_mapping_count
; ++i
, ++plm
)
2424 if (strncmp(s
, plm
->from
, plm
->fromlen
) == 0 && s
[plm
->fromlen
] == '.')
2433 // Choose the output section name to use given an input section name.
2434 // Set *PLEN to the length of the name. *PLEN is initialized to the
2438 Layout::output_section_name(const char* name
, size_t* plen
)
2440 if (Layout::is_linkonce(name
))
2442 // .gnu.linkonce sections are laid out as though they were named
2443 // for the sections are placed into.
2444 return Layout::linkonce_output_name(name
, plen
);
2447 // gcc 4.3 generates the following sorts of section names when it
2448 // needs a section name specific to a function:
2454 // .data.rel.local.FN
2456 // .data.rel.ro.local.FN
2463 // The GNU linker maps all of those to the part before the .FN,
2464 // except that .data.rel.local.FN is mapped to .data, and
2465 // .data.rel.ro.local.FN is mapped to .data.rel.ro. The sections
2466 // beginning with .data.rel.ro.local are grouped together.
2468 // For an anonymous namespace, the string FN can contain a '.'.
2470 // Also of interest: .rodata.strN.N, .rodata.cstN, both of which the
2471 // GNU linker maps to .rodata.
2473 // The .data.rel.ro sections enable a security feature triggered by
2474 // the -z relro option. Section which need to be relocated at
2475 // program startup time but which may be readonly after startup are
2476 // grouped into .data.rel.ro. They are then put into a PT_GNU_RELRO
2477 // segment. The dynamic linker will make that segment writable,
2478 // perform relocations, and then make it read-only. FIXME: We do
2479 // not yet implement this optimization.
2481 // It is hard to handle this in a principled way.
2483 // These are the rules we follow:
2485 // If the section name has no initial '.', or no dot other than an
2486 // initial '.', we use the name unchanged (i.e., "mysection" and
2487 // ".text" are unchanged).
2489 // If the name starts with ".data.rel.ro" we use ".data.rel.ro".
2491 // Otherwise, we drop the second '.' and everything that comes after
2492 // it (i.e., ".text.XXX" becomes ".text").
2494 const char* s
= name
;
2498 const char* sdot
= strchr(s
, '.');
2502 const char* const data_rel_ro
= ".data.rel.ro";
2503 if (strncmp(name
, data_rel_ro
, strlen(data_rel_ro
)) == 0)
2505 *plen
= strlen(data_rel_ro
);
2509 *plen
= sdot
- name
;
2513 // Record the signature of a comdat section, and return whether to
2514 // include it in the link. If GROUP is true, this is a regular
2515 // section group. If GROUP is false, this is a group signature
2516 // derived from the name of a linkonce section. We want linkonce
2517 // signatures and group signatures to block each other, but we don't
2518 // want a linkonce signature to block another linkonce signature.
2521 Layout::add_comdat(const char* signature
, bool group
)
2523 std::string
sig(signature
);
2524 std::pair
<Signatures::iterator
, bool> ins(
2525 this->signatures_
.insert(std::make_pair(sig
, group
)));
2529 // This is the first time we've seen this signature.
2533 if (ins
.first
->second
)
2535 // We've already seen a real section group with this signature.
2540 // This is a real section group, and we've already seen a
2541 // linkonce section with this signature. Record that we've seen
2542 // a section group, and don't include this section group.
2543 ins
.first
->second
= true;
2548 // We've already seen a linkonce section and this is a linkonce
2549 // section. These don't block each other--this may be the same
2550 // symbol name with different section types.
2555 // Store the allocated sections into the section list.
2558 Layout::get_allocated_sections(Section_list
* section_list
) const
2560 for (Section_list::const_iterator p
= this->section_list_
.begin();
2561 p
!= this->section_list_
.end();
2563 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) != 0)
2564 section_list
->push_back(*p
);
2567 // Create an output segment.
2570 Layout::make_output_segment(elfcpp::Elf_Word type
, elfcpp::Elf_Word flags
)
2572 gold_assert(!parameters
->options().relocatable());
2573 Output_segment
* oseg
= new Output_segment(type
, flags
);
2574 this->segment_list_
.push_back(oseg
);
2578 // Write out the Output_sections. Most won't have anything to write,
2579 // since most of the data will come from input sections which are
2580 // handled elsewhere. But some Output_sections do have Output_data.
2583 Layout::write_output_sections(Output_file
* of
) const
2585 for (Section_list::const_iterator p
= this->section_list_
.begin();
2586 p
!= this->section_list_
.end();
2589 if (!(*p
)->after_input_sections())
2594 // Write out data not associated with a section or the symbol table.
2597 Layout::write_data(const Symbol_table
* symtab
, Output_file
* of
) const
2599 if (!parameters
->options().strip_all())
2601 const Output_section
* symtab_section
= this->symtab_section_
;
2602 for (Section_list::const_iterator p
= this->section_list_
.begin();
2603 p
!= this->section_list_
.end();
2606 if ((*p
)->needs_symtab_index())
2608 gold_assert(symtab_section
!= NULL
);
2609 unsigned int index
= (*p
)->symtab_index();
2610 gold_assert(index
> 0 && index
!= -1U);
2611 off_t off
= (symtab_section
->offset()
2612 + index
* symtab_section
->entsize());
2613 symtab
->write_section_symbol(*p
, of
, off
);
2618 const Output_section
* dynsym_section
= this->dynsym_section_
;
2619 for (Section_list::const_iterator p
= this->section_list_
.begin();
2620 p
!= this->section_list_
.end();
2623 if ((*p
)->needs_dynsym_index())
2625 gold_assert(dynsym_section
!= NULL
);
2626 unsigned int index
= (*p
)->dynsym_index();
2627 gold_assert(index
> 0 && index
!= -1U);
2628 off_t off
= (dynsym_section
->offset()
2629 + index
* dynsym_section
->entsize());
2630 symtab
->write_section_symbol(*p
, of
, off
);
2634 // Write out the Output_data which are not in an Output_section.
2635 for (Data_list::const_iterator p
= this->special_output_list_
.begin();
2636 p
!= this->special_output_list_
.end();
2641 // Write out the Output_sections which can only be written after the
2642 // input sections are complete.
2645 Layout::write_sections_after_input_sections(Output_file
* of
)
2647 // Determine the final section offsets, and thus the final output
2648 // file size. Note we finalize the .shstrab last, to allow the
2649 // after_input_section sections to modify their section-names before
2651 if (this->any_postprocessing_sections_
)
2653 off_t off
= this->output_file_size_
;
2654 off
= this->set_section_offsets(off
, POSTPROCESSING_SECTIONS_PASS
);
2656 // Now that we've finalized the names, we can finalize the shstrab.
2658 this->set_section_offsets(off
,
2659 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
);
2661 if (off
> this->output_file_size_
)
2664 this->output_file_size_
= off
;
2668 for (Section_list::const_iterator p
= this->section_list_
.begin();
2669 p
!= this->section_list_
.end();
2672 if ((*p
)->after_input_sections())
2676 this->section_headers_
->write(of
);
2679 // Write out a binary file. This is called after the link is
2680 // complete. IN is the temporary output file we used to generate the
2681 // ELF code. We simply walk through the segments, read them from
2682 // their file offset in IN, and write them to their load address in
2683 // the output file. FIXME: with a bit more work, we could support
2684 // S-records and/or Intel hex format here.
2687 Layout::write_binary(Output_file
* in
) const
2689 gold_assert(this->options_
.oformat_enum()
2690 == General_options::OBJECT_FORMAT_BINARY
);
2692 // Get the size of the binary file.
2693 uint64_t max_load_address
= 0;
2694 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
2695 p
!= this->segment_list_
.end();
2698 if ((*p
)->type() == elfcpp::PT_LOAD
&& (*p
)->filesz() > 0)
2700 uint64_t max_paddr
= (*p
)->paddr() + (*p
)->filesz();
2701 if (max_paddr
> max_load_address
)
2702 max_load_address
= max_paddr
;
2706 Output_file
out(parameters
->options().output_file_name());
2707 out
.open(max_load_address
);
2709 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
2710 p
!= this->segment_list_
.end();
2713 if ((*p
)->type() == elfcpp::PT_LOAD
&& (*p
)->filesz() > 0)
2715 const unsigned char* vin
= in
->get_input_view((*p
)->offset(),
2717 unsigned char* vout
= out
.get_output_view((*p
)->paddr(),
2719 memcpy(vout
, vin
, (*p
)->filesz());
2720 out
.write_output_view((*p
)->paddr(), (*p
)->filesz(), vout
);
2721 in
->free_input_view((*p
)->offset(), (*p
)->filesz(), vin
);
2728 // Print statistical information to stderr. This is used for --stats.
2731 Layout::print_stats() const
2733 this->namepool_
.print_stats("section name pool");
2734 this->sympool_
.print_stats("output symbol name pool");
2735 this->dynpool_
.print_stats("dynamic name pool");
2737 for (Section_list::const_iterator p
= this->section_list_
.begin();
2738 p
!= this->section_list_
.end();
2740 (*p
)->print_merge_stats();
2743 // Write_sections_task methods.
2745 // We can always run this task.
2748 Write_sections_task::is_runnable()
2753 // We need to unlock both OUTPUT_SECTIONS_BLOCKER and FINAL_BLOCKER
2757 Write_sections_task::locks(Task_locker
* tl
)
2759 tl
->add(this, this->output_sections_blocker_
);
2760 tl
->add(this, this->final_blocker_
);
2763 // Run the task--write out the data.
2766 Write_sections_task::run(Workqueue
*)
2768 this->layout_
->write_output_sections(this->of_
);
2771 // Write_data_task methods.
2773 // We can always run this task.
2776 Write_data_task::is_runnable()
2781 // We need to unlock FINAL_BLOCKER when finished.
2784 Write_data_task::locks(Task_locker
* tl
)
2786 tl
->add(this, this->final_blocker_
);
2789 // Run the task--write out the data.
2792 Write_data_task::run(Workqueue
*)
2794 this->layout_
->write_data(this->symtab_
, this->of_
);
2797 // Write_symbols_task methods.
2799 // We can always run this task.
2802 Write_symbols_task::is_runnable()
2807 // We need to unlock FINAL_BLOCKER when finished.
2810 Write_symbols_task::locks(Task_locker
* tl
)
2812 tl
->add(this, this->final_blocker_
);
2815 // Run the task--write out the symbols.
2818 Write_symbols_task::run(Workqueue
*)
2820 this->symtab_
->write_globals(this->input_objects_
, this->sympool_
,
2821 this->dynpool_
, this->of_
);
2824 // Write_after_input_sections_task methods.
2826 // We can only run this task after the input sections have completed.
2829 Write_after_input_sections_task::is_runnable()
2831 if (this->input_sections_blocker_
->is_blocked())
2832 return this->input_sections_blocker_
;
2836 // We need to unlock FINAL_BLOCKER when finished.
2839 Write_after_input_sections_task::locks(Task_locker
* tl
)
2841 tl
->add(this, this->final_blocker_
);
2847 Write_after_input_sections_task::run(Workqueue
*)
2849 this->layout_
->write_sections_after_input_sections(this->of_
);
2852 // Close_task_runner methods.
2854 // Run the task--close the file.
2857 Close_task_runner::run(Workqueue
*, const Task
*)
2859 // If we've been asked to create a binary file, we do so here.
2860 if (this->options_
->oformat_enum() != General_options::OBJECT_FORMAT_ELF
)
2861 this->layout_
->write_binary(this->of_
);
2866 // Instantiate the templates we need. We could use the configure
2867 // script to restrict this to only the ones for implemented targets.
2869 #ifdef HAVE_TARGET_32_LITTLE
2872 Layout::layout
<32, false>(Sized_relobj
<32, false>* object
, unsigned int shndx
,
2874 const elfcpp::Shdr
<32, false>& shdr
,
2875 unsigned int, unsigned int, off_t
*);
2878 #ifdef HAVE_TARGET_32_BIG
2881 Layout::layout
<32, true>(Sized_relobj
<32, true>* object
, unsigned int shndx
,
2883 const elfcpp::Shdr
<32, true>& shdr
,
2884 unsigned int, unsigned int, off_t
*);
2887 #ifdef HAVE_TARGET_64_LITTLE
2890 Layout::layout
<64, false>(Sized_relobj
<64, false>* object
, unsigned int shndx
,
2892 const elfcpp::Shdr
<64, false>& shdr
,
2893 unsigned int, unsigned int, off_t
*);
2896 #ifdef HAVE_TARGET_64_BIG
2899 Layout::layout
<64, true>(Sized_relobj
<64, true>* object
, unsigned int shndx
,
2901 const elfcpp::Shdr
<64, true>& shdr
,
2902 unsigned int, unsigned int, off_t
*);
2905 #ifdef HAVE_TARGET_32_LITTLE
2908 Layout::layout_reloc
<32, false>(Sized_relobj
<32, false>* object
,
2909 unsigned int reloc_shndx
,
2910 const elfcpp::Shdr
<32, false>& shdr
,
2911 Output_section
* data_section
,
2912 Relocatable_relocs
* rr
);
2915 #ifdef HAVE_TARGET_32_BIG
2918 Layout::layout_reloc
<32, true>(Sized_relobj
<32, true>* object
,
2919 unsigned int reloc_shndx
,
2920 const elfcpp::Shdr
<32, true>& shdr
,
2921 Output_section
* data_section
,
2922 Relocatable_relocs
* rr
);
2925 #ifdef HAVE_TARGET_64_LITTLE
2928 Layout::layout_reloc
<64, false>(Sized_relobj
<64, false>* object
,
2929 unsigned int reloc_shndx
,
2930 const elfcpp::Shdr
<64, false>& shdr
,
2931 Output_section
* data_section
,
2932 Relocatable_relocs
* rr
);
2935 #ifdef HAVE_TARGET_64_BIG
2938 Layout::layout_reloc
<64, true>(Sized_relobj
<64, true>* object
,
2939 unsigned int reloc_shndx
,
2940 const elfcpp::Shdr
<64, true>& shdr
,
2941 Output_section
* data_section
,
2942 Relocatable_relocs
* rr
);
2945 #ifdef HAVE_TARGET_32_LITTLE
2948 Layout::layout_group
<32, false>(Symbol_table
* symtab
,
2949 Sized_relobj
<32, false>* object
,
2951 const char* group_section_name
,
2952 const char* signature
,
2953 const elfcpp::Shdr
<32, false>& shdr
,
2954 const elfcpp::Elf_Word
* contents
);
2957 #ifdef HAVE_TARGET_32_BIG
2960 Layout::layout_group
<32, true>(Symbol_table
* symtab
,
2961 Sized_relobj
<32, true>* object
,
2963 const char* group_section_name
,
2964 const char* signature
,
2965 const elfcpp::Shdr
<32, true>& shdr
,
2966 const elfcpp::Elf_Word
* contents
);
2969 #ifdef HAVE_TARGET_64_LITTLE
2972 Layout::layout_group
<64, false>(Symbol_table
* symtab
,
2973 Sized_relobj
<64, false>* object
,
2975 const char* group_section_name
,
2976 const char* signature
,
2977 const elfcpp::Shdr
<64, false>& shdr
,
2978 const elfcpp::Elf_Word
* contents
);
2981 #ifdef HAVE_TARGET_64_BIG
2984 Layout::layout_group
<64, true>(Symbol_table
* symtab
,
2985 Sized_relobj
<64, true>* object
,
2987 const char* group_section_name
,
2988 const char* signature
,
2989 const elfcpp::Shdr
<64, true>& shdr
,
2990 const elfcpp::Elf_Word
* contents
);
2993 #ifdef HAVE_TARGET_32_LITTLE
2996 Layout::layout_eh_frame
<32, false>(Sized_relobj
<32, false>* object
,
2997 const unsigned char* symbols
,
2999 const unsigned char* symbol_names
,
3000 off_t symbol_names_size
,
3002 const elfcpp::Shdr
<32, false>& shdr
,
3003 unsigned int reloc_shndx
,
3004 unsigned int reloc_type
,
3008 #ifdef HAVE_TARGET_32_BIG
3011 Layout::layout_eh_frame
<32, true>(Sized_relobj
<32, true>* object
,
3012 const unsigned char* symbols
,
3014 const unsigned char* symbol_names
,
3015 off_t symbol_names_size
,
3017 const elfcpp::Shdr
<32, true>& shdr
,
3018 unsigned int reloc_shndx
,
3019 unsigned int reloc_type
,
3023 #ifdef HAVE_TARGET_64_LITTLE
3026 Layout::layout_eh_frame
<64, false>(Sized_relobj
<64, false>* object
,
3027 const unsigned char* symbols
,
3029 const unsigned char* symbol_names
,
3030 off_t symbol_names_size
,
3032 const elfcpp::Shdr
<64, false>& shdr
,
3033 unsigned int reloc_shndx
,
3034 unsigned int reloc_type
,
3038 #ifdef HAVE_TARGET_64_BIG
3041 Layout::layout_eh_frame
<64, true>(Sized_relobj
<64, true>* object
,
3042 const unsigned char* symbols
,
3044 const unsigned char* symbol_names
,
3045 off_t symbol_names_size
,
3047 const elfcpp::Shdr
<64, true>& shdr
,
3048 unsigned int reloc_shndx
,
3049 unsigned int reloc_type
,
3053 } // End namespace gold.