1 // layout.h -- lay out output file sections for gold -*- C++ -*-
3 // Copyright 2006, 2007, 2008, 2009, 2010, 2011 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.
34 #include "workqueue.h"
37 #include "stringpool.h"
42 class General_options
;
43 class Incremental_inputs
;
44 class Incremental_binary
;
48 class Output_section_data
;
50 class Output_section_headers
;
51 class Output_segment_headers
;
52 class Output_file_header
;
55 class Output_data_reloc_generic
;
56 class Output_data_dynamic
;
57 class Output_symtab_xindex
;
58 class Output_reduced_debug_abbrev_section
;
59 class Output_reduced_debug_info_section
;
64 // Return TRUE if SECNAME is the name of a compressed debug section.
66 is_compressed_debug_section(const char* secname
);
68 // Maintain a list of free space within a section, segment, or file.
69 // Used for incremental update links.
75 : list_(), last_remove_(list_
.begin()), extend_(false), length_(0)
79 init(off_t len
, bool extend
);
82 remove(off_t start
, off_t end
);
85 allocate(off_t len
, uint64_t align
, off_t minoff
);
96 Free_list_node(off_t start
, off_t end
)
97 : start_(start
), end_(end
)
102 typedef std::list
<Free_list_node
>::iterator Iterator
;
105 std::list
<Free_list_node
> list_
;
107 // The last node visited during a remove operation.
108 Iterator last_remove_
;
110 // Whether we can extend past the original length.
113 // The total length of the section, segment, or file.
117 // The total number of free lists used.
118 static unsigned int num_lists
;
119 // The total number of free list nodes used.
120 static unsigned int num_nodes
;
121 // The total number of calls to Free_list::remove.
122 static unsigned int num_removes
;
123 // The total number of nodes visited during calls to Free_list::remove.
124 static unsigned int num_remove_visits
;
125 // The total number of calls to Free_list::allocate.
126 static unsigned int num_allocates
;
127 // The total number of nodes visited during calls to Free_list::allocate.
128 static unsigned int num_allocate_visits
;
131 // This task function handles mapping the input sections to output
132 // sections and laying them out in memory.
134 class Layout_task_runner
: public Task_function_runner
137 // OPTIONS is the command line options, INPUT_OBJECTS is the list of
138 // input objects, SYMTAB is the symbol table, LAYOUT is the layout
140 Layout_task_runner(const General_options
& options
,
141 const Input_objects
* input_objects
,
142 Symbol_table
* symtab
,
146 : options_(options
), input_objects_(input_objects
), symtab_(symtab
),
147 target_(target
), layout_(layout
), mapfile_(mapfile
)
150 // Run the operation.
152 run(Workqueue
*, const Task
*);
155 Layout_task_runner(const Layout_task_runner
&);
156 Layout_task_runner
& operator=(const Layout_task_runner
&);
158 const General_options
& options_
;
159 const Input_objects
* input_objects_
;
160 Symbol_table
* symtab_
;
166 // This class holds information about the comdat group or
167 // .gnu.linkonce section that will be kept for a given signature.
172 // For a comdat group, we build a mapping from the name of each
173 // section in the group to the section index and the size in object.
174 // When we discard a group in some other object file, we use this
175 // map to figure out which kept section the discarded section is
176 // associated with. We then use that mapping when processing relocs
177 // against discarded sections.
178 struct Comdat_section_info
180 // The section index.
185 Comdat_section_info(unsigned int a_shndx
, uint64_t a_size
)
186 : shndx(a_shndx
), size(a_size
)
190 // Most comdat groups have only one or two sections, so we use a
191 // std::map rather than an Unordered_map to optimize for that case
192 // without paying too heavily for groups with more sections.
193 typedef std::map
<std::string
, Comdat_section_info
> Comdat_group
;
197 : object_(NULL
), shndx_(0), is_comdat_(false), is_group_name_(false)
198 { this->u_
.linkonce_size
= 0; }
200 // We need to support copies for the signature map in the Layout
201 // object, but we should never copy an object after it has been
202 // marked as a comdat section.
203 Kept_section(const Kept_section
& k
)
204 : object_(k
.object_
), shndx_(k
.shndx_
), is_comdat_(false),
205 is_group_name_(k
.is_group_name_
)
207 gold_assert(!k
.is_comdat_
);
208 this->u_
.linkonce_size
= 0;
213 if (this->is_comdat_
)
214 delete this->u_
.group_sections
;
217 // The object where this section lives.
220 { return this->object_
; }
224 set_object(Relobj
* object
)
226 gold_assert(this->object_
== NULL
);
227 this->object_
= object
;
230 // The section index.
233 { return this->shndx_
; }
235 // Set the section index.
237 set_shndx(unsigned int shndx
)
239 gold_assert(this->shndx_
== 0);
240 this->shndx_
= shndx
;
243 // Whether this is a comdat group.
246 { return this->is_comdat_
; }
248 // Set that this is a comdat group.
252 gold_assert(!this->is_comdat_
);
253 this->is_comdat_
= true;
254 this->u_
.group_sections
= new Comdat_group();
257 // Whether this is associated with the name of a group or section
258 // rather than the symbol name derived from a linkonce section.
260 is_group_name() const
261 { return this->is_group_name_
; }
263 // Note that this represents a comdat group rather than a single
267 { this->is_group_name_
= true; }
269 // Add a section to the group list.
271 add_comdat_section(const std::string
& name
, unsigned int shndx
,
274 gold_assert(this->is_comdat_
);
275 Comdat_section_info
sinfo(shndx
, size
);
276 this->u_
.group_sections
->insert(std::make_pair(name
, sinfo
));
279 // Look for a section name in the group list, and return whether it
280 // was found. If found, returns the section index and size.
282 find_comdat_section(const std::string
& name
, unsigned int* pshndx
,
283 uint64_t* psize
) const
285 gold_assert(this->is_comdat_
);
286 Comdat_group::const_iterator p
= this->u_
.group_sections
->find(name
);
287 if (p
== this->u_
.group_sections
->end())
289 *pshndx
= p
->second
.shndx
;
290 *psize
= p
->second
.size
;
294 // If there is only one section in the group list, return true, and
295 // return the section index and size.
297 find_single_comdat_section(unsigned int* pshndx
, uint64_t* psize
) const
299 gold_assert(this->is_comdat_
);
300 if (this->u_
.group_sections
->size() != 1)
302 Comdat_group::const_iterator p
= this->u_
.group_sections
->begin();
303 *pshndx
= p
->second
.shndx
;
304 *psize
= p
->second
.size
;
308 // Return the size of a linkonce section.
310 linkonce_size() const
312 gold_assert(!this->is_comdat_
);
313 return this->u_
.linkonce_size
;
316 // Set the size of a linkonce section.
318 set_linkonce_size(uint64_t size
)
320 gold_assert(!this->is_comdat_
);
321 this->u_
.linkonce_size
= size
;
326 Kept_section
& operator=(const Kept_section
&);
328 // The object containing the comdat group or .gnu.linkonce section.
330 // Index of the group section for comdats and the section itself for
333 // True if this is for a comdat group rather than a .gnu.linkonce
336 // The Kept_sections are values of a mapping, that maps names to
337 // them. This field is true if this struct is associated with the
338 // name of a comdat or .gnu.linkonce, false if it is associated with
339 // the name of a symbol obtained from the .gnu.linkonce.* name
340 // through some heuristics.
344 // If the is_comdat_ field is true, this holds a map from names of
345 // the sections in the group to section indexes in object_ and to
347 Comdat_group
* group_sections
;
348 // If the is_comdat_ field is false, this holds the size of the
350 uint64_t linkonce_size
;
354 // The ordering for output sections. This controls how output
355 // sections are ordered within a PT_LOAD output segment.
357 enum Output_section_order
359 // Unspecified. Used for non-load segments. Also used for the file
360 // and segment headers.
363 // The PT_INTERP section should come first, so that the dynamic
364 // linker can pick it up quickly.
367 // Loadable read-only note sections come next so that the PT_NOTE
368 // segment is on the first page of the executable.
371 // Put read-only sections used by the dynamic linker early in the
372 // executable to minimize paging.
373 ORDER_DYNAMIC_LINKER
,
375 // Put reloc sections used by the dynamic linker after other
376 // sections used by the dynamic linker; otherwise, objcopy and strip
378 ORDER_DYNAMIC_RELOCS
,
380 // Put the PLT reloc section after the other dynamic relocs;
381 // otherwise, prelink gets confused.
382 ORDER_DYNAMIC_PLT_RELOCS
,
384 // The .init section.
390 // The regular text sections.
393 // The .fini section.
396 // The read-only sections.
399 // The exception frame sections.
402 // The TLS sections come first in the data section.
406 // Local RELRO (read-only after relocation) sections come before
407 // non-local RELRO sections. This data will be fully resolved by
411 // Non-local RELRO sections are grouped together after local RELRO
412 // sections. All RELRO sections must be adjacent so that they can
413 // all be put into a PT_GNU_RELRO segment.
416 // We permit marking exactly one output section as the last RELRO
417 // section. We do this so that the read-only GOT can be adjacent to
421 // Similarly, we permit marking exactly one output section as the
422 // first non-RELRO section.
423 ORDER_NON_RELRO_FIRST
,
425 // The regular data sections come after the RELRO sections.
428 // Large data sections normally go in large data segments.
431 // Group writable notes so that we can have a single PT_NOTE
435 // The small data sections must be at the end of the data sections,
436 // so that they can be adjacent to the small BSS sections.
439 // The BSS sections start here.
441 // The small BSS sections must be at the start of the BSS sections,
442 // so that they can be adjacent to the small data sections.
445 // The regular BSS sections.
448 // The large BSS sections come after the other BSS sections.
455 // This class handles the details of laying out input sections.
460 Layout(int number_of_input_files
, Script_options
*);
464 delete this->relaxation_debug_check_
;
465 delete this->segment_states_
;
468 // For incremental links, record the base file to be modified.
470 set_incremental_base(Incremental_binary
* base
);
474 { return this->incremental_base_
; }
476 // For incremental links, record the initial fixed layout of a section
477 // from the base file, and return a pointer to the Output_section.
478 template<int size
, bool big_endian
>
480 init_fixed_output_section(const char*, elfcpp::Shdr
<size
, big_endian
>&);
482 // Given an input section SHNDX, named NAME, with data in SHDR, from
483 // the object file OBJECT, return the output section where this
484 // input section should go. RELOC_SHNDX is the index of a
485 // relocation section which applies to this section, or 0 if none,
486 // or -1U if more than one. RELOC_TYPE is the type of the
487 // relocation section if there is one. Set *OFFSET to the offset
488 // within the output section.
489 template<int size
, bool big_endian
>
491 layout(Sized_relobj_file
<size
, big_endian
> *object
, unsigned int shndx
,
492 const char* name
, const elfcpp::Shdr
<size
, big_endian
>& shdr
,
493 unsigned int reloc_shndx
, unsigned int reloc_type
, off_t
* offset
);
495 // For incremental updates, allocate a block of memory from the
496 // free list. Find a block starting at or after MINOFF.
498 allocate(off_t len
, uint64_t align
, off_t minoff
)
499 { return this->free_list_
.allocate(len
, align
, minoff
); }
502 find_section_order_index(const std::string
&);
505 read_layout_from_file();
507 // Layout an input reloc section when doing a relocatable link. The
508 // section is RELOC_SHNDX in OBJECT, with data in SHDR.
509 // DATA_SECTION is the reloc section to which it refers. RR is the
510 // relocatable information.
511 template<int size
, bool big_endian
>
513 layout_reloc(Sized_relobj_file
<size
, big_endian
>* object
,
514 unsigned int reloc_shndx
,
515 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
516 Output_section
* data_section
,
517 Relocatable_relocs
* rr
);
519 // Layout a group section when doing a relocatable link.
520 template<int size
, bool big_endian
>
522 layout_group(Symbol_table
* symtab
,
523 Sized_relobj_file
<size
, big_endian
>* object
,
524 unsigned int group_shndx
,
525 const char* group_section_name
,
526 const char* signature
,
527 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
528 elfcpp::Elf_Word flags
,
529 std::vector
<unsigned int>* shndxes
);
531 // Like layout, only for exception frame sections. OBJECT is an
532 // object file. SYMBOLS is the contents of the symbol table
533 // section, with size SYMBOLS_SIZE. SYMBOL_NAMES is the contents of
534 // the symbol name section, with size SYMBOL_NAMES_SIZE. SHNDX is a
535 // .eh_frame section in OBJECT. SHDR is the section header.
536 // RELOC_SHNDX is the index of a relocation section which applies to
537 // this section, or 0 if none, or -1U if more than one. RELOC_TYPE
538 // is the type of the relocation section if there is one. This
539 // returns the output section, and sets *OFFSET to the offset.
540 template<int size
, bool big_endian
>
542 layout_eh_frame(Sized_relobj_file
<size
, big_endian
>* object
,
543 const unsigned char* symbols
,
545 const unsigned char* symbol_names
,
546 off_t symbol_names_size
,
548 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
549 unsigned int reloc_shndx
, unsigned int reloc_type
,
552 // Add .eh_frame information for a PLT. The FDE must start with a
553 // 4-byte PC-relative reference to the start of the PLT, followed by
554 // a 4-byte size of PLT.
556 add_eh_frame_for_plt(Output_data
* plt
, const unsigned char* cie_data
,
557 size_t cie_length
, const unsigned char* fde_data
,
560 // Handle a GNU stack note. This is called once per input object
561 // file. SEEN_GNU_STACK is true if the object file has a
562 // .note.GNU-stack section. GNU_STACK_FLAGS is the section flags
563 // from that section if there was one.
565 layout_gnu_stack(bool seen_gnu_stack
, uint64_t gnu_stack_flags
,
568 // Add an Output_section_data to the layout. This is used for
569 // special sections like the GOT section. ORDER is where the
570 // section should wind up in the output segment. IS_RELRO is true
571 // for relro sections.
573 add_output_section_data(const char* name
, elfcpp::Elf_Word type
,
574 elfcpp::Elf_Xword flags
,
575 Output_section_data
*, Output_section_order order
,
578 // Increase the size of the relro segment by this much.
580 increase_relro(unsigned int s
)
581 { this->increase_relro_
+= s
; }
583 // Create dynamic sections if necessary.
585 create_initial_dynamic_sections(Symbol_table
*);
587 // Define __start and __stop symbols for output sections.
589 define_section_symbols(Symbol_table
*);
591 // Create automatic note sections.
595 // Create sections for linker scripts.
597 create_script_sections()
598 { this->script_options_
->create_script_sections(this); }
600 // Define symbols from any linker script.
602 define_script_symbols(Symbol_table
* symtab
)
603 { this->script_options_
->add_symbols_to_table(symtab
); }
605 // Define symbols for group signatures.
607 define_group_signatures(Symbol_table
*);
609 // Return the Stringpool used for symbol names.
612 { return &this->sympool_
; }
614 // Return the Stringpool used for dynamic symbol names and dynamic
618 { return &this->dynpool_
; }
620 // Return the symtab_xindex section used to hold large section
621 // indexes for the normal symbol table.
622 Output_symtab_xindex
*
623 symtab_xindex() const
624 { return this->symtab_xindex_
; }
626 // Return the dynsym_xindex section used to hold large section
627 // indexes for the dynamic symbol table.
628 Output_symtab_xindex
*
629 dynsym_xindex() const
630 { return this->dynsym_xindex_
; }
632 // Return whether a section is a .gnu.linkonce section, given the
635 is_linkonce(const char* name
)
636 { return strncmp(name
, ".gnu.linkonce", sizeof(".gnu.linkonce") - 1) == 0; }
638 // Whether we have added an input section.
640 have_added_input_section() const
641 { return this->have_added_input_section_
; }
643 // Return true if a section is a debugging section.
645 is_debug_info_section(const char* name
)
647 // Debugging sections can only be recognized by name.
648 return (strncmp(name
, ".debug", sizeof(".debug") - 1) == 0
649 || strncmp(name
, ".zdebug", sizeof(".zdebug") - 1) == 0
650 || strncmp(name
, ".gnu.linkonce.wi.",
651 sizeof(".gnu.linkonce.wi.") - 1) == 0
652 || strncmp(name
, ".line", sizeof(".line") - 1) == 0
653 || strncmp(name
, ".stab", sizeof(".stab") - 1) == 0);
656 // Return true if RELOBJ is an input file whose base name matches
657 // FILE_NAME. The base name must have an extension of ".o", and
658 // must be exactly FILE_NAME.o or FILE_NAME, one character, ".o".
660 match_file_name(const Relobj
* relobj
, const char* file_name
);
662 // Return whether section SHNDX in RELOBJ is a .ctors/.dtors section
663 // with more than one word being mapped to a .init_array/.fini_array
666 is_ctors_in_init_array(Relobj
* relobj
, unsigned int shndx
) const;
668 // Check if a comdat group or .gnu.linkonce section with the given
669 // NAME is selected for the link. If there is already a section,
670 // *KEPT_SECTION is set to point to the signature and the function
671 // returns false. Otherwise, OBJECT, SHNDX,IS_COMDAT, and
672 // IS_GROUP_NAME are recorded for this NAME in the layout object,
673 // *KEPT_SECTION is set to the internal copy and the function return
676 find_or_add_kept_section(const std::string
& name
, Relobj
* object
,
677 unsigned int shndx
, bool is_comdat
,
678 bool is_group_name
, Kept_section
** kept_section
);
680 // Finalize the layout after all the input sections have been added.
682 finalize(const Input_objects
*, Symbol_table
*, Target
*, const Task
*);
684 // Return whether any sections require postprocessing.
686 any_postprocessing_sections() const
687 { return this->any_postprocessing_sections_
; }
689 // Return the size of the output file.
691 output_file_size() const
692 { return this->output_file_size_
; }
694 // Return the TLS segment. This will return NULL if there isn't
698 { return this->tls_segment_
; }
700 // Return the normal symbol table.
702 symtab_section() const
704 gold_assert(this->symtab_section_
!= NULL
);
705 return this->symtab_section_
;
708 // Return the file offset of the normal symbol table.
710 symtab_section_offset() const;
712 // Return the section index of the normal symbol tabl.e
714 symtab_section_shndx() const;
716 // Return the dynamic symbol table.
718 dynsym_section() const
720 gold_assert(this->dynsym_section_
!= NULL
);
721 return this->dynsym_section_
;
724 // Return the dynamic tags.
727 { return this->dynamic_data_
; }
729 // Write out the output sections.
731 write_output_sections(Output_file
* of
) const;
733 // Write out data not associated with an input file or the symbol
736 write_data(const Symbol_table
*, Output_file
*) const;
738 // Write out output sections which can not be written until all the
739 // input sections are complete.
741 write_sections_after_input_sections(Output_file
* of
);
743 // Return an output section named NAME, or NULL if there is none.
745 find_output_section(const char* name
) const;
747 // Return an output segment of type TYPE, with segment flags SET set
748 // and segment flags CLEAR clear. Return NULL if there is none.
750 find_output_segment(elfcpp::PT type
, elfcpp::Elf_Word set
,
751 elfcpp::Elf_Word clear
) const;
753 // Return the number of segments we expect to produce.
755 expected_segment_count() const;
757 // Set a flag to indicate that an object file uses the static TLS model.
760 { this->has_static_tls_
= true; }
762 // Return true if any object file uses the static TLS model.
764 has_static_tls() const
765 { return this->has_static_tls_
; }
767 // Return the options which may be set by a linker script.
770 { return this->script_options_
; }
772 const Script_options
*
773 script_options() const
774 { return this->script_options_
; }
776 // Return the object managing inputs in incremental build. NULL in
777 // non-incremental builds.
779 incremental_inputs() const
780 { return this->incremental_inputs_
; }
782 // For the target-specific code to add dynamic tags which are common
785 add_target_dynamic_tags(bool use_rel
, const Output_data
* plt_got
,
786 const Output_data
* plt_rel
,
787 const Output_data_reloc_generic
* dyn_rel
,
788 bool add_debug
, bool dynrel_includes_plt
);
790 // Compute and write out the build ID if needed.
792 write_build_id(Output_file
*) const;
794 // Rewrite output file in binary format.
796 write_binary(Output_file
* in
) const;
798 // Print output sections to the map file.
800 print_to_mapfile(Mapfile
*) const;
802 // Dump statistical information to stderr.
806 // A list of segments.
808 typedef std::vector
<Output_segment
*> Segment_list
;
810 // A list of sections.
812 typedef std::vector
<Output_section
*> Section_list
;
814 // The list of information to write out which is not attached to
815 // either a section or a segment.
816 typedef std::vector
<Output_data
*> Data_list
;
818 // Store the allocated sections into the section list. This is used
819 // by the linker script code.
821 get_allocated_sections(Section_list
*) const;
823 // Make a section for a linker script to hold data.
825 make_output_section_for_script(const char* name
,
826 Script_sections::Section_type section_type
);
828 // Make a segment. This is used by the linker script code.
830 make_output_segment(elfcpp::Elf_Word type
, elfcpp::Elf_Word flags
);
832 // Return the number of segments.
834 segment_count() const
835 { return this->segment_list_
.size(); }
837 // Map from section flags to segment flags.
838 static elfcpp::Elf_Word
839 section_flags_to_segment(elfcpp::Elf_Xword flags
);
841 // Attach sections to segments.
843 attach_sections_to_segments();
845 // For relaxation clean up, we need to know output section data created
846 // from a linker script.
848 new_output_section_data_from_script(Output_section_data
* posd
)
850 if (this->record_output_section_data_from_script_
)
851 this->script_output_section_data_list_
.push_back(posd
);
854 // Return section list.
857 { return this->section_list_
; }
860 Layout(const Layout
&);
861 Layout
& operator=(const Layout
&);
863 // Mapping from input section names to output section names.
864 struct Section_name_mapping
871 static const Section_name_mapping section_name_mapping
[];
872 static const int section_name_mapping_count
;
874 // During a relocatable link, a list of group sections and
876 struct Group_signature
878 // The group section.
879 Output_section
* section
;
881 const char* signature
;
884 : section(NULL
), signature(NULL
)
887 Group_signature(Output_section
* sectiona
, const char* signaturea
)
888 : section(sectiona
), signature(signaturea
)
891 typedef std::vector
<Group_signature
> Group_signatures
;
893 // Create a note section, filling in the header.
895 create_note(const char* name
, int note_type
, const char* section_name
,
896 size_t descsz
, bool allocate
, size_t* trailing_padding
);
898 // Create a note section for gold version.
902 // Record whether the stack must be executable.
904 create_executable_stack_info();
906 // Create a build ID note if needed.
910 // Link .stab and .stabstr sections.
912 link_stabs_sections();
914 // Create .gnu_incremental_inputs and .gnu_incremental_strtab sections needed
915 // for the next run of incremental linking to check what has changed.
917 create_incremental_info_sections(Symbol_table
*);
919 // Find the first read-only PT_LOAD segment, creating one if
922 find_first_load_seg();
924 // Count the local symbols in the regular symbol table and the dynamic
925 // symbol table, and build the respective string pools.
927 count_local_symbols(const Task
*, const Input_objects
*);
929 // Create the output sections for the symbol table.
931 create_symtab_sections(const Input_objects
*, Symbol_table
*,
932 unsigned int, off_t
*);
934 // Create the .shstrtab section.
938 // Create the section header table.
940 create_shdrs(const Output_section
* shstrtab_section
, off_t
*);
942 // Create the dynamic symbol table.
944 create_dynamic_symtab(const Input_objects
*, Symbol_table
*,
945 Output_section
** pdynstr
,
946 unsigned int* plocal_dynamic_count
,
947 std::vector
<Symbol
*>* pdynamic_symbols
,
950 // Assign offsets to each local portion of the dynamic symbol table.
952 assign_local_dynsym_offsets(const Input_objects
*);
954 // Finish the .dynamic section and PT_DYNAMIC segment.
956 finish_dynamic_section(const Input_objects
*, const Symbol_table
*);
958 // Set the size of the _DYNAMIC symbol.
960 set_dynamic_symbol_size(const Symbol_table
*);
962 // Create the .interp section and PT_INTERP segment.
964 create_interp(const Target
* target
);
966 // Create the version sections.
968 create_version_sections(const Versions
*,
970 unsigned int local_symcount
,
971 const std::vector
<Symbol
*>& dynamic_symbols
,
972 const Output_section
* dynstr
);
974 template<int size
, bool big_endian
>
976 sized_create_version_sections(const Versions
* versions
,
978 unsigned int local_symcount
,
979 const std::vector
<Symbol
*>& dynamic_symbols
,
980 const Output_section
* dynstr
);
982 // Return whether to include this section in the link.
983 template<int size
, bool big_endian
>
985 include_section(Sized_relobj_file
<size
, big_endian
>* object
, const char* name
,
986 const elfcpp::Shdr
<size
, big_endian
>&);
988 // Return the output section name to use given an input section
989 // name. Set *PLEN to the length of the name. *PLEN must be
990 // initialized to the length of NAME.
992 output_section_name(const Relobj
*, const char* name
, size_t* plen
);
994 // Return the number of allocated output sections.
996 allocated_output_section_count() const;
998 // Return the output section for NAME, TYPE and FLAGS.
1000 get_output_section(const char* name
, Stringpool::Key name_key
,
1001 elfcpp::Elf_Word type
, elfcpp::Elf_Xword flags
,
1002 Output_section_order order
, bool is_relro
);
1004 // Choose the output section for NAME in RELOBJ.
1006 choose_output_section(const Relobj
* relobj
, const char* name
,
1007 elfcpp::Elf_Word type
, elfcpp::Elf_Xword flags
,
1008 bool is_input_section
, Output_section_order order
,
1011 // Create a new Output_section.
1013 make_output_section(const char* name
, elfcpp::Elf_Word type
,
1014 elfcpp::Elf_Xword flags
, Output_section_order order
,
1017 // Attach a section to a segment.
1019 attach_section_to_segment(Output_section
*);
1021 // Get section order.
1022 Output_section_order
1023 default_section_order(Output_section
*, bool is_relro_local
);
1025 // Attach an allocated section to a segment.
1027 attach_allocated_section_to_segment(Output_section
*);
1029 // Make the .eh_frame section.
1031 make_eh_frame_section(const Relobj
*);
1033 // Set the final file offsets of all the segments.
1035 set_segment_offsets(const Target
*, Output_segment
*, unsigned int* pshndx
);
1037 // Set the file offsets of the sections when doing a relocatable
1040 set_relocatable_section_offsets(Output_data
*, unsigned int* pshndx
);
1042 // Set the final file offsets of all the sections not associated
1043 // with a segment. We set section offsets in three passes: the
1044 // first handles all allocated sections, the second sections that
1045 // require postprocessing, and the last the late-bound STRTAB
1046 // sections (probably only shstrtab, which is the one we care about
1047 // because it holds section names).
1048 enum Section_offset_pass
1050 BEFORE_INPUT_SECTIONS_PASS
,
1051 POSTPROCESSING_SECTIONS_PASS
,
1052 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
1055 set_section_offsets(off_t
, Section_offset_pass pass
);
1057 // Set the final section indexes of all the sections not associated
1058 // with a segment. Returns the next unused index.
1060 set_section_indexes(unsigned int pshndx
);
1062 // Set the section addresses when using a script.
1064 set_section_addresses_from_script(Symbol_table
*);
1066 // Find appropriate places or orphan sections in a script.
1068 place_orphan_sections_in_script();
1070 // Return whether SEG1 comes before SEG2 in the output file.
1072 segment_precedes(const Output_segment
* seg1
, const Output_segment
* seg2
);
1074 // Use to save and restore segments during relaxation.
1075 typedef Unordered_map
<const Output_segment
*, const Output_segment
*>
1078 // Save states of current output segments.
1080 save_segments(Segment_states
*);
1082 // Restore output segment states.
1084 restore_segments(const Segment_states
*);
1086 // Clean up after relaxation so that it is possible to lay out the
1087 // sections and segments again.
1089 clean_up_after_relaxation();
1091 // Doing preparation work for relaxation. This is factored out to make
1092 // Layout::finalized a bit smaller and easier to read.
1094 prepare_for_relaxation();
1096 // Main body of the relaxation loop, which lays out the section.
1098 relaxation_loop_body(int, Target
*, Symbol_table
*, Output_segment
**,
1099 Output_segment
*, Output_segment_headers
*,
1100 Output_file_header
*, unsigned int*);
1102 // A mapping used for kept comdats/.gnu.linkonce group signatures.
1103 typedef Unordered_map
<std::string
, Kept_section
> Signatures
;
1105 // Mapping from input section name/type/flags to output section. We
1106 // use canonicalized strings here.
1108 typedef std::pair
<Stringpool::Key
,
1109 std::pair
<elfcpp::Elf_Word
, elfcpp::Elf_Xword
> > Key
;
1114 operator()(const Key
& k
) const;
1117 typedef Unordered_map
<Key
, Output_section
*, Hash_key
> Section_name_map
;
1119 // A comparison class for segments.
1121 class Compare_segments
1124 Compare_segments(Layout
* layout
)
1129 operator()(const Output_segment
* seg1
, const Output_segment
* seg2
)
1130 { return this->layout_
->segment_precedes(seg1
, seg2
); }
1136 typedef std::vector
<Output_section_data
*> Output_section_data_list
;
1138 // Debug checker class.
1139 class Relaxation_debug_check
1142 Relaxation_debug_check()
1146 // Check that sections and special data are in reset states.
1148 check_output_data_for_reset_values(const Layout::Section_list
&,
1149 const Layout::Data_list
&);
1151 // Record information of a section list.
1153 read_sections(const Layout::Section_list
&);
1155 // Verify a section list with recorded information.
1157 verify_sections(const Layout::Section_list
&);
1160 // Information we care about a section.
1163 // Output section described by this.
1164 Output_section
* output_section
;
1173 // Section information.
1174 std::vector
<Section_info
> section_infos_
;
1177 // The number of input files, for sizing tables.
1178 int number_of_input_files_
;
1179 // Information set by scripts or by command line options.
1180 Script_options
* script_options_
;
1181 // The output section names.
1182 Stringpool namepool_
;
1183 // The output symbol names.
1184 Stringpool sympool_
;
1185 // The dynamic strings, if needed.
1186 Stringpool dynpool_
;
1187 // The list of group sections and linkonce sections which we have seen.
1188 Signatures signatures_
;
1189 // The mapping from input section name/type/flags to output sections.
1190 Section_name_map section_name_map_
;
1191 // The list of output segments.
1192 Segment_list segment_list_
;
1193 // The list of output sections.
1194 Section_list section_list_
;
1195 // The list of output sections which are not attached to any output
1197 Section_list unattached_section_list_
;
1198 // The list of unattached Output_data objects which require special
1199 // handling because they are not Output_sections.
1200 Data_list special_output_list_
;
1201 // The section headers.
1202 Output_section_headers
* section_headers_
;
1203 // A pointer to the PT_TLS segment if there is one.
1204 Output_segment
* tls_segment_
;
1205 // A pointer to the PT_GNU_RELRO segment if there is one.
1206 Output_segment
* relro_segment_
;
1207 // A pointer to the PT_INTERP segment if there is one.
1208 Output_segment
* interp_segment_
;
1209 // A backend may increase the size of the PT_GNU_RELRO segment if
1210 // there is one. This is the amount to increase it by.
1211 unsigned int increase_relro_
;
1212 // The SHT_SYMTAB output section.
1213 Output_section
* symtab_section_
;
1214 // The SHT_SYMTAB_SHNDX for the regular symbol table if there is one.
1215 Output_symtab_xindex
* symtab_xindex_
;
1216 // The SHT_DYNSYM output section if there is one.
1217 Output_section
* dynsym_section_
;
1218 // The SHT_SYMTAB_SHNDX for the dynamic symbol table if there is one.
1219 Output_symtab_xindex
* dynsym_xindex_
;
1220 // The SHT_DYNAMIC output section if there is one.
1221 Output_section
* dynamic_section_
;
1222 // The _DYNAMIC symbol if there is one.
1223 Symbol
* dynamic_symbol_
;
1224 // The dynamic data which goes into dynamic_section_.
1225 Output_data_dynamic
* dynamic_data_
;
1226 // The exception frame output section if there is one.
1227 Output_section
* eh_frame_section_
;
1228 // The exception frame data for eh_frame_section_.
1229 Eh_frame
* eh_frame_data_
;
1230 // Whether we have added eh_frame_data_ to the .eh_frame section.
1231 bool added_eh_frame_data_
;
1232 // The exception frame header output section if there is one.
1233 Output_section
* eh_frame_hdr_section_
;
1234 // The space for the build ID checksum if there is one.
1235 Output_section_data
* build_id_note_
;
1236 // The output section containing dwarf abbreviations
1237 Output_reduced_debug_abbrev_section
* debug_abbrev_
;
1238 // The output section containing the dwarf debug info tree
1239 Output_reduced_debug_info_section
* debug_info_
;
1240 // A list of group sections and their signatures.
1241 Group_signatures group_signatures_
;
1242 // The size of the output file.
1243 off_t output_file_size_
;
1244 // Whether we have added an input section to an output section.
1245 bool have_added_input_section_
;
1246 // Whether we have attached the sections to the segments.
1247 bool sections_are_attached_
;
1248 // Whether we have seen an object file marked to require an
1249 // executable stack.
1250 bool input_requires_executable_stack_
;
1251 // Whether we have seen at least one object file with an executable
1253 bool input_with_gnu_stack_note_
;
1254 // Whether we have seen at least one object file without an
1255 // executable stack marker.
1256 bool input_without_gnu_stack_note_
;
1257 // Whether we have seen an object file that uses the static TLS model.
1258 bool has_static_tls_
;
1259 // Whether any sections require postprocessing.
1260 bool any_postprocessing_sections_
;
1261 // Whether we have resized the signatures_ hash table.
1262 bool resized_signatures_
;
1263 // Whether we have created a .stab*str output section.
1264 bool have_stabstr_section_
;
1265 // In incremental build, holds information check the inputs and build the
1266 // .gnu_incremental_inputs section.
1267 Incremental_inputs
* incremental_inputs_
;
1268 // Whether we record output section data created in script
1269 bool record_output_section_data_from_script_
;
1270 // List of output data that needs to be removed at relaxation clean up.
1271 Output_section_data_list script_output_section_data_list_
;
1272 // Structure to save segment states before entering the relaxation loop.
1273 Segment_states
* segment_states_
;
1274 // A relaxation debug checker. We only create one when in debugging mode.
1275 Relaxation_debug_check
* relaxation_debug_check_
;
1276 // Hash a pattern to its position in the section ordering file.
1277 Unordered_map
<std::string
, unsigned int> input_section_position_
;
1278 // Vector of glob only patterns in the section_ordering file.
1279 std::vector
<std::string
> input_section_glob_
;
1280 // For incremental links, the base file to be modified.
1281 Incremental_binary
* incremental_base_
;
1282 // For incremental links, a list of free space within the file.
1283 Free_list free_list_
;
1286 // This task handles writing out data in output sections which is not
1287 // part of an input section, or which requires special handling. When
1288 // this is done, it unblocks both output_sections_blocker and
1291 class Write_sections_task
: public Task
1294 Write_sections_task(const Layout
* layout
, Output_file
* of
,
1295 Task_token
* output_sections_blocker
,
1296 Task_token
* final_blocker
)
1297 : layout_(layout
), of_(of
),
1298 output_sections_blocker_(output_sections_blocker
),
1299 final_blocker_(final_blocker
)
1302 // The standard Task methods.
1308 locks(Task_locker
*);
1315 { return "Write_sections_task"; }
1318 class Write_sections_locker
;
1320 const Layout
* layout_
;
1322 Task_token
* output_sections_blocker_
;
1323 Task_token
* final_blocker_
;
1326 // This task handles writing out data which is not part of a section
1329 class Write_data_task
: public Task
1332 Write_data_task(const Layout
* layout
, const Symbol_table
* symtab
,
1333 Output_file
* of
, Task_token
* final_blocker
)
1334 : layout_(layout
), symtab_(symtab
), of_(of
), final_blocker_(final_blocker
)
1337 // The standard Task methods.
1343 locks(Task_locker
*);
1350 { return "Write_data_task"; }
1353 const Layout
* layout_
;
1354 const Symbol_table
* symtab_
;
1356 Task_token
* final_blocker_
;
1359 // This task handles writing out the global symbols.
1361 class Write_symbols_task
: public Task
1364 Write_symbols_task(const Layout
* layout
, const Symbol_table
* symtab
,
1365 const Input_objects
* input_objects
,
1366 const Stringpool
* sympool
, const Stringpool
* dynpool
,
1367 Output_file
* of
, Task_token
* final_blocker
)
1368 : layout_(layout
), symtab_(symtab
), input_objects_(input_objects
),
1369 sympool_(sympool
), dynpool_(dynpool
), of_(of
),
1370 final_blocker_(final_blocker
)
1373 // The standard Task methods.
1379 locks(Task_locker
*);
1386 { return "Write_symbols_task"; }
1389 const Layout
* layout_
;
1390 const Symbol_table
* symtab_
;
1391 const Input_objects
* input_objects_
;
1392 const Stringpool
* sympool_
;
1393 const Stringpool
* dynpool_
;
1395 Task_token
* final_blocker_
;
1398 // This task handles writing out data in output sections which can't
1399 // be written out until all the input sections have been handled.
1400 // This is for sections whose contents is based on the contents of
1401 // other output sections.
1403 class Write_after_input_sections_task
: public Task
1406 Write_after_input_sections_task(Layout
* layout
, Output_file
* of
,
1407 Task_token
* input_sections_blocker
,
1408 Task_token
* final_blocker
)
1409 : layout_(layout
), of_(of
),
1410 input_sections_blocker_(input_sections_blocker
),
1411 final_blocker_(final_blocker
)
1414 // The standard Task methods.
1420 locks(Task_locker
*);
1427 { return "Write_after_input_sections_task"; }
1432 Task_token
* input_sections_blocker_
;
1433 Task_token
* final_blocker_
;
1436 // This task function handles closing the file.
1438 class Close_task_runner
: public Task_function_runner
1441 Close_task_runner(const General_options
* options
, const Layout
* layout
,
1443 : options_(options
), layout_(layout
), of_(of
)
1446 // Run the operation.
1448 run(Workqueue
*, const Task
*);
1451 const General_options
* options_
;
1452 const Layout
* layout_
;
1456 // A small helper function to align an address.
1459 align_address(uint64_t address
, uint64_t addralign
)
1462 address
= (address
+ addralign
- 1) &~ (addralign
- 1);
1466 } // End namespace gold.
1468 #endif // !defined(GOLD_LAYOUT_H)