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
);
496 is_section_ordering_specified()
497 { return this->section_ordering_specified_
; }
500 set_section_ordering_specified()
501 { this->section_ordering_specified_
= true; }
503 // For incremental updates, allocate a block of memory from the
504 // free list. Find a block starting at or after MINOFF.
506 allocate(off_t len
, uint64_t align
, off_t minoff
)
507 { return this->free_list_
.allocate(len
, align
, minoff
); }
510 find_section_order_index(const std::string
&);
512 // Read the sequence of input sections from the file specified with
513 // linker option --section-ordering-file.
515 read_layout_from_file();
517 // Layout an input reloc section when doing a relocatable link. The
518 // section is RELOC_SHNDX in OBJECT, with data in SHDR.
519 // DATA_SECTION is the reloc section to which it refers. RR is the
520 // relocatable information.
521 template<int size
, bool big_endian
>
523 layout_reloc(Sized_relobj_file
<size
, big_endian
>* object
,
524 unsigned int reloc_shndx
,
525 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
526 Output_section
* data_section
,
527 Relocatable_relocs
* rr
);
529 // Layout a group section when doing a relocatable link.
530 template<int size
, bool big_endian
>
532 layout_group(Symbol_table
* symtab
,
533 Sized_relobj_file
<size
, big_endian
>* object
,
534 unsigned int group_shndx
,
535 const char* group_section_name
,
536 const char* signature
,
537 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
538 elfcpp::Elf_Word flags
,
539 std::vector
<unsigned int>* shndxes
);
541 // Like layout, only for exception frame sections. OBJECT is an
542 // object file. SYMBOLS is the contents of the symbol table
543 // section, with size SYMBOLS_SIZE. SYMBOL_NAMES is the contents of
544 // the symbol name section, with size SYMBOL_NAMES_SIZE. SHNDX is a
545 // .eh_frame section in OBJECT. SHDR is the section header.
546 // RELOC_SHNDX is the index of a relocation section which applies to
547 // this section, or 0 if none, or -1U if more than one. RELOC_TYPE
548 // is the type of the relocation section if there is one. This
549 // returns the output section, and sets *OFFSET to the offset.
550 template<int size
, bool big_endian
>
552 layout_eh_frame(Sized_relobj_file
<size
, big_endian
>* object
,
553 const unsigned char* symbols
,
555 const unsigned char* symbol_names
,
556 off_t symbol_names_size
,
558 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
559 unsigned int reloc_shndx
, unsigned int reloc_type
,
562 // Add .eh_frame information for a PLT. The FDE must start with a
563 // 4-byte PC-relative reference to the start of the PLT, followed by
564 // a 4-byte size of PLT.
566 add_eh_frame_for_plt(Output_data
* plt
, const unsigned char* cie_data
,
567 size_t cie_length
, const unsigned char* fde_data
,
570 // Handle a GNU stack note. This is called once per input object
571 // file. SEEN_GNU_STACK is true if the object file has a
572 // .note.GNU-stack section. GNU_STACK_FLAGS is the section flags
573 // from that section if there was one.
575 layout_gnu_stack(bool seen_gnu_stack
, uint64_t gnu_stack_flags
,
578 // Add an Output_section_data to the layout. This is used for
579 // special sections like the GOT section. ORDER is where the
580 // section should wind up in the output segment. IS_RELRO is true
581 // for relro sections.
583 add_output_section_data(const char* name
, elfcpp::Elf_Word type
,
584 elfcpp::Elf_Xword flags
,
585 Output_section_data
*, Output_section_order order
,
588 // Increase the size of the relro segment by this much.
590 increase_relro(unsigned int s
)
591 { this->increase_relro_
+= s
; }
593 // Create dynamic sections if necessary.
595 create_initial_dynamic_sections(Symbol_table
*);
597 // Define __start and __stop symbols for output sections.
599 define_section_symbols(Symbol_table
*);
601 // Create automatic note sections.
605 // Create sections for linker scripts.
607 create_script_sections()
608 { this->script_options_
->create_script_sections(this); }
610 // Define symbols from any linker script.
612 define_script_symbols(Symbol_table
* symtab
)
613 { this->script_options_
->add_symbols_to_table(symtab
); }
615 // Define symbols for group signatures.
617 define_group_signatures(Symbol_table
*);
619 // Return the Stringpool used for symbol names.
622 { return &this->sympool_
; }
624 // Return the Stringpool used for dynamic symbol names and dynamic
628 { return &this->dynpool_
; }
630 // Return the .dynamic output section. This is only valid after the
631 // layout has been finalized.
633 dynamic_section() const
634 { return this->dynamic_section_
; }
636 // Return the symtab_xindex section used to hold large section
637 // indexes for the normal symbol table.
638 Output_symtab_xindex
*
639 symtab_xindex() const
640 { return this->symtab_xindex_
; }
642 // Return the dynsym_xindex section used to hold large section
643 // indexes for the dynamic symbol table.
644 Output_symtab_xindex
*
645 dynsym_xindex() const
646 { return this->dynsym_xindex_
; }
648 // Return whether a section is a .gnu.linkonce section, given the
651 is_linkonce(const char* name
)
652 { return strncmp(name
, ".gnu.linkonce", sizeof(".gnu.linkonce") - 1) == 0; }
654 // Whether we have added an input section.
656 have_added_input_section() const
657 { return this->have_added_input_section_
; }
659 // Return true if a section is a debugging section.
661 is_debug_info_section(const char* name
)
663 // Debugging sections can only be recognized by name.
664 return (strncmp(name
, ".debug", sizeof(".debug") - 1) == 0
665 || strncmp(name
, ".zdebug", sizeof(".zdebug") - 1) == 0
666 || strncmp(name
, ".gnu.linkonce.wi.",
667 sizeof(".gnu.linkonce.wi.") - 1) == 0
668 || strncmp(name
, ".line", sizeof(".line") - 1) == 0
669 || strncmp(name
, ".stab", sizeof(".stab") - 1) == 0);
672 // Return true if RELOBJ is an input file whose base name matches
673 // FILE_NAME. The base name must have an extension of ".o", and
674 // must be exactly FILE_NAME.o or FILE_NAME, one character, ".o".
676 match_file_name(const Relobj
* relobj
, const char* file_name
);
678 // Return whether section SHNDX in RELOBJ is a .ctors/.dtors section
679 // with more than one word being mapped to a .init_array/.fini_array
682 is_ctors_in_init_array(Relobj
* relobj
, unsigned int shndx
) const;
684 // Check if a comdat group or .gnu.linkonce section with the given
685 // NAME is selected for the link. If there is already a section,
686 // *KEPT_SECTION is set to point to the signature and the function
687 // returns false. Otherwise, OBJECT, SHNDX,IS_COMDAT, and
688 // IS_GROUP_NAME are recorded for this NAME in the layout object,
689 // *KEPT_SECTION is set to the internal copy and the function return
692 find_or_add_kept_section(const std::string
& name
, Relobj
* object
,
693 unsigned int shndx
, bool is_comdat
,
694 bool is_group_name
, Kept_section
** kept_section
);
696 // Finalize the layout after all the input sections have been added.
698 finalize(const Input_objects
*, Symbol_table
*, Target
*, const Task
*);
700 // Return whether any sections require postprocessing.
702 any_postprocessing_sections() const
703 { return this->any_postprocessing_sections_
; }
705 // Return the size of the output file.
707 output_file_size() const
708 { return this->output_file_size_
; }
710 // Return the TLS segment. This will return NULL if there isn't
714 { return this->tls_segment_
; }
716 // Return the normal symbol table.
718 symtab_section() const
720 gold_assert(this->symtab_section_
!= NULL
);
721 return this->symtab_section_
;
724 // Return the file offset of the normal symbol table.
726 symtab_section_offset() const;
728 // Return the section index of the normal symbol tabl.e
730 symtab_section_shndx() const;
732 // Return the dynamic symbol table.
734 dynsym_section() const
736 gold_assert(this->dynsym_section_
!= NULL
);
737 return this->dynsym_section_
;
740 // Return the dynamic tags.
743 { return this->dynamic_data_
; }
745 // Write out the output sections.
747 write_output_sections(Output_file
* of
) const;
749 // Write out data not associated with an input file or the symbol
752 write_data(const Symbol_table
*, Output_file
*) const;
754 // Write out output sections which can not be written until all the
755 // input sections are complete.
757 write_sections_after_input_sections(Output_file
* of
);
759 // Return an output section named NAME, or NULL if there is none.
761 find_output_section(const char* name
) const;
763 // Return an output segment of type TYPE, with segment flags SET set
764 // and segment flags CLEAR clear. Return NULL if there is none.
766 find_output_segment(elfcpp::PT type
, elfcpp::Elf_Word set
,
767 elfcpp::Elf_Word clear
) const;
769 // Return the number of segments we expect to produce.
771 expected_segment_count() const;
773 // Set a flag to indicate that an object file uses the static TLS model.
776 { this->has_static_tls_
= true; }
778 // Return true if any object file uses the static TLS model.
780 has_static_tls() const
781 { return this->has_static_tls_
; }
783 // Return the options which may be set by a linker script.
786 { return this->script_options_
; }
788 const Script_options
*
789 script_options() const
790 { return this->script_options_
; }
792 // Return the object managing inputs in incremental build. NULL in
793 // non-incremental builds.
795 incremental_inputs() const
796 { return this->incremental_inputs_
; }
798 // For the target-specific code to add dynamic tags which are common
801 add_target_dynamic_tags(bool use_rel
, const Output_data
* plt_got
,
802 const Output_data
* plt_rel
,
803 const Output_data_reloc_generic
* dyn_rel
,
804 bool add_debug
, bool dynrel_includes_plt
);
806 // Compute and write out the build ID if needed.
808 write_build_id(Output_file
*) const;
810 // Rewrite output file in binary format.
812 write_binary(Output_file
* in
) const;
814 // Print output sections to the map file.
816 print_to_mapfile(Mapfile
*) const;
818 // Dump statistical information to stderr.
822 // A list of segments.
824 typedef std::vector
<Output_segment
*> Segment_list
;
826 // A list of sections.
828 typedef std::vector
<Output_section
*> Section_list
;
830 // The list of information to write out which is not attached to
831 // either a section or a segment.
832 typedef std::vector
<Output_data
*> Data_list
;
834 // Store the allocated sections into the section list. This is used
835 // by the linker script code.
837 get_allocated_sections(Section_list
*) const;
839 // Make a section for a linker script to hold data.
841 make_output_section_for_script(const char* name
,
842 Script_sections::Section_type section_type
);
844 // Make a segment. This is used by the linker script code.
846 make_output_segment(elfcpp::Elf_Word type
, elfcpp::Elf_Word flags
);
848 // Return the number of segments.
850 segment_count() const
851 { return this->segment_list_
.size(); }
853 // Map from section flags to segment flags.
854 static elfcpp::Elf_Word
855 section_flags_to_segment(elfcpp::Elf_Xword flags
);
857 // Attach sections to segments.
859 attach_sections_to_segments();
861 // For relaxation clean up, we need to know output section data created
862 // from a linker script.
864 new_output_section_data_from_script(Output_section_data
* posd
)
866 if (this->record_output_section_data_from_script_
)
867 this->script_output_section_data_list_
.push_back(posd
);
870 // Return section list.
873 { return this->section_list_
; }
876 Layout(const Layout
&);
877 Layout
& operator=(const Layout
&);
879 // Mapping from input section names to output section names.
880 struct Section_name_mapping
887 static const Section_name_mapping section_name_mapping
[];
888 static const int section_name_mapping_count
;
890 // During a relocatable link, a list of group sections and
892 struct Group_signature
894 // The group section.
895 Output_section
* section
;
897 const char* signature
;
900 : section(NULL
), signature(NULL
)
903 Group_signature(Output_section
* sectiona
, const char* signaturea
)
904 : section(sectiona
), signature(signaturea
)
907 typedef std::vector
<Group_signature
> Group_signatures
;
909 // Create a note section, filling in the header.
911 create_note(const char* name
, int note_type
, const char* section_name
,
912 size_t descsz
, bool allocate
, size_t* trailing_padding
);
914 // Create a note section for gold version.
918 // Record whether the stack must be executable.
920 create_executable_stack_info();
922 // Create a build ID note if needed.
926 // Link .stab and .stabstr sections.
928 link_stabs_sections();
930 // Create .gnu_incremental_inputs and .gnu_incremental_strtab sections needed
931 // for the next run of incremental linking to check what has changed.
933 create_incremental_info_sections(Symbol_table
*);
935 // Find the first read-only PT_LOAD segment, creating one if
938 find_first_load_seg();
940 // Count the local symbols in the regular symbol table and the dynamic
941 // symbol table, and build the respective string pools.
943 count_local_symbols(const Task
*, const Input_objects
*);
945 // Create the output sections for the symbol table.
947 create_symtab_sections(const Input_objects
*, Symbol_table
*,
948 unsigned int, off_t
*);
950 // Create the .shstrtab section.
954 // Create the section header table.
956 create_shdrs(const Output_section
* shstrtab_section
, off_t
*);
958 // Create the dynamic symbol table.
960 create_dynamic_symtab(const Input_objects
*, Symbol_table
*,
961 Output_section
** pdynstr
,
962 unsigned int* plocal_dynamic_count
,
963 std::vector
<Symbol
*>* pdynamic_symbols
,
966 // Assign offsets to each local portion of the dynamic symbol table.
968 assign_local_dynsym_offsets(const Input_objects
*);
970 // Finish the .dynamic section and PT_DYNAMIC segment.
972 finish_dynamic_section(const Input_objects
*, const Symbol_table
*);
974 // Set the size of the _DYNAMIC symbol.
976 set_dynamic_symbol_size(const Symbol_table
*);
978 // Create the .interp section and PT_INTERP segment.
980 create_interp(const Target
* target
);
982 // Create the version sections.
984 create_version_sections(const Versions
*,
986 unsigned int local_symcount
,
987 const std::vector
<Symbol
*>& dynamic_symbols
,
988 const Output_section
* dynstr
);
990 template<int size
, bool big_endian
>
992 sized_create_version_sections(const Versions
* versions
,
994 unsigned int local_symcount
,
995 const std::vector
<Symbol
*>& dynamic_symbols
,
996 const Output_section
* dynstr
);
998 // Return whether to include this section in the link.
999 template<int size
, bool big_endian
>
1001 include_section(Sized_relobj_file
<size
, big_endian
>* object
, const char* name
,
1002 const elfcpp::Shdr
<size
, big_endian
>&);
1004 // Return the output section name to use given an input section
1005 // name. Set *PLEN to the length of the name. *PLEN must be
1006 // initialized to the length of NAME.
1008 output_section_name(const Relobj
*, const char* name
, size_t* plen
);
1010 // Return the number of allocated output sections.
1012 allocated_output_section_count() const;
1014 // Return the output section for NAME, TYPE and FLAGS.
1016 get_output_section(const char* name
, Stringpool::Key name_key
,
1017 elfcpp::Elf_Word type
, elfcpp::Elf_Xword flags
,
1018 Output_section_order order
, bool is_relro
);
1020 // Choose the output section for NAME in RELOBJ.
1022 choose_output_section(const Relobj
* relobj
, const char* name
,
1023 elfcpp::Elf_Word type
, elfcpp::Elf_Xword flags
,
1024 bool is_input_section
, Output_section_order order
,
1027 // Create a new Output_section.
1029 make_output_section(const char* name
, elfcpp::Elf_Word type
,
1030 elfcpp::Elf_Xword flags
, Output_section_order order
,
1033 // Attach a section to a segment.
1035 attach_section_to_segment(Output_section
*);
1037 // Get section order.
1038 Output_section_order
1039 default_section_order(Output_section
*, bool is_relro_local
);
1041 // Attach an allocated section to a segment.
1043 attach_allocated_section_to_segment(Output_section
*);
1045 // Make the .eh_frame section.
1047 make_eh_frame_section(const Relobj
*);
1049 // Set the final file offsets of all the segments.
1051 set_segment_offsets(const Target
*, Output_segment
*, unsigned int* pshndx
);
1053 // Set the file offsets of the sections when doing a relocatable
1056 set_relocatable_section_offsets(Output_data
*, unsigned int* pshndx
);
1058 // Set the final file offsets of all the sections not associated
1059 // with a segment. We set section offsets in three passes: the
1060 // first handles all allocated sections, the second sections that
1061 // require postprocessing, and the last the late-bound STRTAB
1062 // sections (probably only shstrtab, which is the one we care about
1063 // because it holds section names).
1064 enum Section_offset_pass
1066 BEFORE_INPUT_SECTIONS_PASS
,
1067 POSTPROCESSING_SECTIONS_PASS
,
1068 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
1071 set_section_offsets(off_t
, Section_offset_pass pass
);
1073 // Set the final section indexes of all the sections not associated
1074 // with a segment. Returns the next unused index.
1076 set_section_indexes(unsigned int pshndx
);
1078 // Set the section addresses when using a script.
1080 set_section_addresses_from_script(Symbol_table
*);
1082 // Find appropriate places or orphan sections in a script.
1084 place_orphan_sections_in_script();
1086 // Return whether SEG1 comes before SEG2 in the output file.
1088 segment_precedes(const Output_segment
* seg1
, const Output_segment
* seg2
);
1090 // Use to save and restore segments during relaxation.
1091 typedef Unordered_map
<const Output_segment
*, const Output_segment
*>
1094 // Save states of current output segments.
1096 save_segments(Segment_states
*);
1098 // Restore output segment states.
1100 restore_segments(const Segment_states
*);
1102 // Clean up after relaxation so that it is possible to lay out the
1103 // sections and segments again.
1105 clean_up_after_relaxation();
1107 // Doing preparation work for relaxation. This is factored out to make
1108 // Layout::finalized a bit smaller and easier to read.
1110 prepare_for_relaxation();
1112 // Main body of the relaxation loop, which lays out the section.
1114 relaxation_loop_body(int, Target
*, Symbol_table
*, Output_segment
**,
1115 Output_segment
*, Output_segment_headers
*,
1116 Output_file_header
*, unsigned int*);
1118 // A mapping used for kept comdats/.gnu.linkonce group signatures.
1119 typedef Unordered_map
<std::string
, Kept_section
> Signatures
;
1121 // Mapping from input section name/type/flags to output section. We
1122 // use canonicalized strings here.
1124 typedef std::pair
<Stringpool::Key
,
1125 std::pair
<elfcpp::Elf_Word
, elfcpp::Elf_Xword
> > Key
;
1130 operator()(const Key
& k
) const;
1133 typedef Unordered_map
<Key
, Output_section
*, Hash_key
> Section_name_map
;
1135 // A comparison class for segments.
1137 class Compare_segments
1140 Compare_segments(Layout
* layout
)
1145 operator()(const Output_segment
* seg1
, const Output_segment
* seg2
)
1146 { return this->layout_
->segment_precedes(seg1
, seg2
); }
1152 typedef std::vector
<Output_section_data
*> Output_section_data_list
;
1154 // Debug checker class.
1155 class Relaxation_debug_check
1158 Relaxation_debug_check()
1162 // Check that sections and special data are in reset states.
1164 check_output_data_for_reset_values(const Layout::Section_list
&,
1165 const Layout::Data_list
&);
1167 // Record information of a section list.
1169 read_sections(const Layout::Section_list
&);
1171 // Verify a section list with recorded information.
1173 verify_sections(const Layout::Section_list
&);
1176 // Information we care about a section.
1179 // Output section described by this.
1180 Output_section
* output_section
;
1189 // Section information.
1190 std::vector
<Section_info
> section_infos_
;
1193 // The number of input files, for sizing tables.
1194 int number_of_input_files_
;
1195 // Information set by scripts or by command line options.
1196 Script_options
* script_options_
;
1197 // The output section names.
1198 Stringpool namepool_
;
1199 // The output symbol names.
1200 Stringpool sympool_
;
1201 // The dynamic strings, if needed.
1202 Stringpool dynpool_
;
1203 // The list of group sections and linkonce sections which we have seen.
1204 Signatures signatures_
;
1205 // The mapping from input section name/type/flags to output sections.
1206 Section_name_map section_name_map_
;
1207 // The list of output segments.
1208 Segment_list segment_list_
;
1209 // The list of output sections.
1210 Section_list section_list_
;
1211 // The list of output sections which are not attached to any output
1213 Section_list unattached_section_list_
;
1214 // The list of unattached Output_data objects which require special
1215 // handling because they are not Output_sections.
1216 Data_list special_output_list_
;
1217 // The section headers.
1218 Output_section_headers
* section_headers_
;
1219 // A pointer to the PT_TLS segment if there is one.
1220 Output_segment
* tls_segment_
;
1221 // A pointer to the PT_GNU_RELRO segment if there is one.
1222 Output_segment
* relro_segment_
;
1223 // A pointer to the PT_INTERP segment if there is one.
1224 Output_segment
* interp_segment_
;
1225 // A backend may increase the size of the PT_GNU_RELRO segment if
1226 // there is one. This is the amount to increase it by.
1227 unsigned int increase_relro_
;
1228 // The SHT_SYMTAB output section.
1229 Output_section
* symtab_section_
;
1230 // The SHT_SYMTAB_SHNDX for the regular symbol table if there is one.
1231 Output_symtab_xindex
* symtab_xindex_
;
1232 // The SHT_DYNSYM output section if there is one.
1233 Output_section
* dynsym_section_
;
1234 // The SHT_SYMTAB_SHNDX for the dynamic symbol table if there is one.
1235 Output_symtab_xindex
* dynsym_xindex_
;
1236 // The SHT_DYNAMIC output section if there is one.
1237 Output_section
* dynamic_section_
;
1238 // The _DYNAMIC symbol if there is one.
1239 Symbol
* dynamic_symbol_
;
1240 // The dynamic data which goes into dynamic_section_.
1241 Output_data_dynamic
* dynamic_data_
;
1242 // The exception frame output section if there is one.
1243 Output_section
* eh_frame_section_
;
1244 // The exception frame data for eh_frame_section_.
1245 Eh_frame
* eh_frame_data_
;
1246 // Whether we have added eh_frame_data_ to the .eh_frame section.
1247 bool added_eh_frame_data_
;
1248 // The exception frame header output section if there is one.
1249 Output_section
* eh_frame_hdr_section_
;
1250 // The space for the build ID checksum if there is one.
1251 Output_section_data
* build_id_note_
;
1252 // The output section containing dwarf abbreviations
1253 Output_reduced_debug_abbrev_section
* debug_abbrev_
;
1254 // The output section containing the dwarf debug info tree
1255 Output_reduced_debug_info_section
* debug_info_
;
1256 // A list of group sections and their signatures.
1257 Group_signatures group_signatures_
;
1258 // The size of the output file.
1259 off_t output_file_size_
;
1260 // Whether we have added an input section to an output section.
1261 bool have_added_input_section_
;
1262 // Whether we have attached the sections to the segments.
1263 bool sections_are_attached_
;
1264 // Whether we have seen an object file marked to require an
1265 // executable stack.
1266 bool input_requires_executable_stack_
;
1267 // Whether we have seen at least one object file with an executable
1269 bool input_with_gnu_stack_note_
;
1270 // Whether we have seen at least one object file without an
1271 // executable stack marker.
1272 bool input_without_gnu_stack_note_
;
1273 // Whether we have seen an object file that uses the static TLS model.
1274 bool has_static_tls_
;
1275 // Whether any sections require postprocessing.
1276 bool any_postprocessing_sections_
;
1277 // Whether we have resized the signatures_ hash table.
1278 bool resized_signatures_
;
1279 // Whether we have created a .stab*str output section.
1280 bool have_stabstr_section_
;
1281 // True if the input sections in the output sections should be sorted
1282 // as specified in a section ordering file.
1283 bool section_ordering_specified_
;
1284 // In incremental build, holds information check the inputs and build the
1285 // .gnu_incremental_inputs section.
1286 Incremental_inputs
* incremental_inputs_
;
1287 // Whether we record output section data created in script
1288 bool record_output_section_data_from_script_
;
1289 // List of output data that needs to be removed at relaxation clean up.
1290 Output_section_data_list script_output_section_data_list_
;
1291 // Structure to save segment states before entering the relaxation loop.
1292 Segment_states
* segment_states_
;
1293 // A relaxation debug checker. We only create one when in debugging mode.
1294 Relaxation_debug_check
* relaxation_debug_check_
;
1295 // Hash a pattern to its position in the section ordering file.
1296 Unordered_map
<std::string
, unsigned int> input_section_position_
;
1297 // Vector of glob only patterns in the section_ordering file.
1298 std::vector
<std::string
> input_section_glob_
;
1299 // For incremental links, the base file to be modified.
1300 Incremental_binary
* incremental_base_
;
1301 // For incremental links, a list of free space within the file.
1302 Free_list free_list_
;
1305 // This task handles writing out data in output sections which is not
1306 // part of an input section, or which requires special handling. When
1307 // this is done, it unblocks both output_sections_blocker and
1310 class Write_sections_task
: public Task
1313 Write_sections_task(const Layout
* layout
, Output_file
* of
,
1314 Task_token
* output_sections_blocker
,
1315 Task_token
* final_blocker
)
1316 : layout_(layout
), of_(of
),
1317 output_sections_blocker_(output_sections_blocker
),
1318 final_blocker_(final_blocker
)
1321 // The standard Task methods.
1327 locks(Task_locker
*);
1334 { return "Write_sections_task"; }
1337 class Write_sections_locker
;
1339 const Layout
* layout_
;
1341 Task_token
* output_sections_blocker_
;
1342 Task_token
* final_blocker_
;
1345 // This task handles writing out data which is not part of a section
1348 class Write_data_task
: public Task
1351 Write_data_task(const Layout
* layout
, const Symbol_table
* symtab
,
1352 Output_file
* of
, Task_token
* final_blocker
)
1353 : layout_(layout
), symtab_(symtab
), of_(of
), final_blocker_(final_blocker
)
1356 // The standard Task methods.
1362 locks(Task_locker
*);
1369 { return "Write_data_task"; }
1372 const Layout
* layout_
;
1373 const Symbol_table
* symtab_
;
1375 Task_token
* final_blocker_
;
1378 // This task handles writing out the global symbols.
1380 class Write_symbols_task
: public Task
1383 Write_symbols_task(const Layout
* layout
, const Symbol_table
* symtab
,
1384 const Input_objects
* input_objects
,
1385 const Stringpool
* sympool
, const Stringpool
* dynpool
,
1386 Output_file
* of
, Task_token
* final_blocker
)
1387 : layout_(layout
), symtab_(symtab
), input_objects_(input_objects
),
1388 sympool_(sympool
), dynpool_(dynpool
), of_(of
),
1389 final_blocker_(final_blocker
)
1392 // The standard Task methods.
1398 locks(Task_locker
*);
1405 { return "Write_symbols_task"; }
1408 const Layout
* layout_
;
1409 const Symbol_table
* symtab_
;
1410 const Input_objects
* input_objects_
;
1411 const Stringpool
* sympool_
;
1412 const Stringpool
* dynpool_
;
1414 Task_token
* final_blocker_
;
1417 // This task handles writing out data in output sections which can't
1418 // be written out until all the input sections have been handled.
1419 // This is for sections whose contents is based on the contents of
1420 // other output sections.
1422 class Write_after_input_sections_task
: public Task
1425 Write_after_input_sections_task(Layout
* layout
, Output_file
* of
,
1426 Task_token
* input_sections_blocker
,
1427 Task_token
* final_blocker
)
1428 : layout_(layout
), of_(of
),
1429 input_sections_blocker_(input_sections_blocker
),
1430 final_blocker_(final_blocker
)
1433 // The standard Task methods.
1439 locks(Task_locker
*);
1446 { return "Write_after_input_sections_task"; }
1451 Task_token
* input_sections_blocker_
;
1452 Task_token
* final_blocker_
;
1455 // This task function handles closing the file.
1457 class Close_task_runner
: public Task_function_runner
1460 Close_task_runner(const General_options
* options
, const Layout
* layout
,
1462 : options_(options
), layout_(layout
), of_(of
)
1465 // Run the operation.
1467 run(Workqueue
*, const Task
*);
1470 const General_options
* options_
;
1471 const Layout
* layout_
;
1475 // A small helper function to align an address.
1478 align_address(uint64_t address
, uint64_t addralign
)
1481 address
= (address
+ addralign
- 1) &~ (addralign
- 1);
1485 } // End namespace gold.
1487 #endif // !defined(GOLD_LAYOUT_H)