1 // layout.cc -- lay out output file sections for gold
3 // Copyright (C) 2006-2014 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 "libiberty.h"
38 #include "parameters.h"
42 #include "script-sections.h"
47 #include "gdb-index.h"
48 #include "compressed_output.h"
49 #include "reduced_debug_output.h"
52 #include "descriptors.h"
54 #include "incremental.h"
62 // The total number of free lists used.
63 unsigned int Free_list::num_lists
= 0;
64 // The total number of free list nodes used.
65 unsigned int Free_list::num_nodes
= 0;
66 // The total number of calls to Free_list::remove.
67 unsigned int Free_list::num_removes
= 0;
68 // The total number of nodes visited during calls to Free_list::remove.
69 unsigned int Free_list::num_remove_visits
= 0;
70 // The total number of calls to Free_list::allocate.
71 unsigned int Free_list::num_allocates
= 0;
72 // The total number of nodes visited during calls to Free_list::allocate.
73 unsigned int Free_list::num_allocate_visits
= 0;
75 // Initialize the free list. Creates a single free list node that
76 // describes the entire region of length LEN. If EXTEND is true,
77 // allocate() is allowed to extend the region beyond its initial
81 Free_list::init(off_t len
, bool extend
)
83 this->list_
.push_front(Free_list_node(0, len
));
84 this->last_remove_
= this->list_
.begin();
85 this->extend_
= extend
;
87 ++Free_list::num_lists
;
88 ++Free_list::num_nodes
;
91 // Remove a chunk from the free list. Because we start with a single
92 // node that covers the entire section, and remove chunks from it one
93 // at a time, we do not need to coalesce chunks or handle cases that
94 // span more than one free node. We expect to remove chunks from the
95 // free list in order, and we expect to have only a few chunks of free
96 // space left (corresponding to files that have changed since the last
97 // incremental link), so a simple linear list should provide sufficient
101 Free_list::remove(off_t start
, off_t end
)
105 gold_assert(start
< end
);
107 ++Free_list::num_removes
;
109 Iterator p
= this->last_remove_
;
110 if (p
->start_
> start
)
111 p
= this->list_
.begin();
113 for (; p
!= this->list_
.end(); ++p
)
115 ++Free_list::num_remove_visits
;
116 // Find a node that wholly contains the indicated region.
117 if (p
->start_
<= start
&& p
->end_
>= end
)
119 // Case 1: the indicated region spans the whole node.
120 // Add some fuzz to avoid creating tiny free chunks.
121 if (p
->start_
+ 3 >= start
&& p
->end_
<= end
+ 3)
122 p
= this->list_
.erase(p
);
123 // Case 2: remove a chunk from the start of the node.
124 else if (p
->start_
+ 3 >= start
)
126 // Case 3: remove a chunk from the end of the node.
127 else if (p
->end_
<= end
+ 3)
129 // Case 4: remove a chunk from the middle, and split
130 // the node into two.
133 Free_list_node
newnode(p
->start_
, start
);
135 this->list_
.insert(p
, newnode
);
136 ++Free_list::num_nodes
;
138 this->last_remove_
= p
;
143 // Did not find a node containing the given chunk. This could happen
144 // because a small chunk was already removed due to the fuzz.
145 gold_debug(DEBUG_INCREMENTAL
,
146 "Free_list::remove(%d,%d) not found",
147 static_cast<int>(start
), static_cast<int>(end
));
150 // Allocate a chunk of size LEN from the free list. Returns -1ULL
151 // if a sufficiently large chunk of free space is not found.
152 // We use a simple first-fit algorithm.
155 Free_list::allocate(off_t len
, uint64_t align
, off_t minoff
)
157 gold_debug(DEBUG_INCREMENTAL
,
158 "Free_list::allocate(%08lx, %d, %08lx)",
159 static_cast<long>(len
), static_cast<int>(align
),
160 static_cast<long>(minoff
));
162 return align_address(minoff
, align
);
164 ++Free_list::num_allocates
;
166 // We usually want to drop free chunks smaller than 4 bytes.
167 // If we need to guarantee a minimum hole size, though, we need
168 // to keep track of all free chunks.
169 const int fuzz
= this->min_hole_
> 0 ? 0 : 3;
171 for (Iterator p
= this->list_
.begin(); p
!= this->list_
.end(); ++p
)
173 ++Free_list::num_allocate_visits
;
174 off_t start
= p
->start_
> minoff
? p
->start_
: minoff
;
175 start
= align_address(start
, align
);
176 off_t end
= start
+ len
;
177 if (end
> p
->end_
&& p
->end_
== this->length_
&& this->extend_
)
182 if (end
== p
->end_
|| (end
<= p
->end_
- this->min_hole_
))
184 if (p
->start_
+ fuzz
>= start
&& p
->end_
<= end
+ fuzz
)
185 this->list_
.erase(p
);
186 else if (p
->start_
+ fuzz
>= start
)
188 else if (p
->end_
<= end
+ fuzz
)
192 Free_list_node
newnode(p
->start_
, start
);
194 this->list_
.insert(p
, newnode
);
195 ++Free_list::num_nodes
;
202 off_t start
= align_address(this->length_
, align
);
203 this->length_
= start
+ len
;
209 // Dump the free list (for debugging).
213 gold_info("Free list:\n start end length\n");
214 for (Iterator p
= this->list_
.begin(); p
!= this->list_
.end(); ++p
)
215 gold_info(" %08lx %08lx %08lx", static_cast<long>(p
->start_
),
216 static_cast<long>(p
->end_
),
217 static_cast<long>(p
->end_
- p
->start_
));
220 // Print the statistics for the free lists.
222 Free_list::print_stats()
224 fprintf(stderr
, _("%s: total free lists: %u\n"),
225 program_name
, Free_list::num_lists
);
226 fprintf(stderr
, _("%s: total free list nodes: %u\n"),
227 program_name
, Free_list::num_nodes
);
228 fprintf(stderr
, _("%s: calls to Free_list::remove: %u\n"),
229 program_name
, Free_list::num_removes
);
230 fprintf(stderr
, _("%s: nodes visited: %u\n"),
231 program_name
, Free_list::num_remove_visits
);
232 fprintf(stderr
, _("%s: calls to Free_list::allocate: %u\n"),
233 program_name
, Free_list::num_allocates
);
234 fprintf(stderr
, _("%s: nodes visited: %u\n"),
235 program_name
, Free_list::num_allocate_visits
);
238 // A Hash_task computes the MD5 checksum of an array of char.
239 // It has a blocker on either side (i.e., the task cannot run until
240 // the first is unblocked, and it unblocks the second after running).
242 class Hash_task
: public Task
245 Hash_task(const unsigned char* src
,
248 Task_token
* build_id_blocker
,
249 Task_token
* final_blocker
)
250 : src_(src
), size_(size
), dst_(dst
), build_id_blocker_(build_id_blocker
),
251 final_blocker_(final_blocker
)
256 { md5_buffer(reinterpret_cast<const char*>(src_
), size_
, dst_
); }
261 // Unblock FINAL_BLOCKER_ when done.
263 locks(Task_locker
* tl
)
264 { tl
->add(this, this->final_blocker_
); }
268 { return "Hash_task"; }
271 const unsigned char* const src_
;
273 unsigned char* const dst_
;
274 Task_token
* const build_id_blocker_
;
275 Task_token
* const final_blocker_
;
279 Hash_task::is_runnable()
281 if (this->build_id_blocker_
->is_blocked())
282 return this->build_id_blocker_
;
286 // Layout::Relaxation_debug_check methods.
288 // Check that sections and special data are in reset states.
289 // We do not save states for Output_sections and special Output_data.
290 // So we check that they have not assigned any addresses or offsets.
291 // clean_up_after_relaxation simply resets their addresses and offsets.
293 Layout::Relaxation_debug_check::check_output_data_for_reset_values(
294 const Layout::Section_list
& sections
,
295 const Layout::Data_list
& special_outputs
,
296 const Layout::Data_list
& relax_outputs
)
298 for(Layout::Section_list::const_iterator p
= sections
.begin();
301 gold_assert((*p
)->address_and_file_offset_have_reset_values());
303 for(Layout::Data_list::const_iterator p
= special_outputs
.begin();
304 p
!= special_outputs
.end();
306 gold_assert((*p
)->address_and_file_offset_have_reset_values());
308 gold_assert(relax_outputs
.empty());
311 // Save information of SECTIONS for checking later.
314 Layout::Relaxation_debug_check::read_sections(
315 const Layout::Section_list
& sections
)
317 for(Layout::Section_list::const_iterator p
= sections
.begin();
321 Output_section
* os
= *p
;
323 info
.output_section
= os
;
324 info
.address
= os
->is_address_valid() ? os
->address() : 0;
325 info
.data_size
= os
->is_data_size_valid() ? os
->data_size() : -1;
326 info
.offset
= os
->is_offset_valid()? os
->offset() : -1 ;
327 this->section_infos_
.push_back(info
);
331 // Verify SECTIONS using previously recorded information.
334 Layout::Relaxation_debug_check::verify_sections(
335 const Layout::Section_list
& sections
)
338 for(Layout::Section_list::const_iterator p
= sections
.begin();
342 Output_section
* os
= *p
;
343 uint64_t address
= os
->is_address_valid() ? os
->address() : 0;
344 off_t data_size
= os
->is_data_size_valid() ? os
->data_size() : -1;
345 off_t offset
= os
->is_offset_valid()? os
->offset() : -1 ;
347 if (i
>= this->section_infos_
.size())
349 gold_fatal("Section_info of %s missing.\n", os
->name());
351 const Section_info
& info
= this->section_infos_
[i
];
352 if (os
!= info
.output_section
)
353 gold_fatal("Section order changed. Expecting %s but see %s\n",
354 info
.output_section
->name(), os
->name());
355 if (address
!= info
.address
356 || data_size
!= info
.data_size
357 || offset
!= info
.offset
)
358 gold_fatal("Section %s changed.\n", os
->name());
362 // Layout_task_runner methods.
364 // Lay out the sections. This is called after all the input objects
368 Layout_task_runner::run(Workqueue
* workqueue
, const Task
* task
)
370 // See if any of the input definitions violate the One Definition Rule.
371 // TODO: if this is too slow, do this as a task, rather than inline.
372 this->symtab_
->detect_odr_violations(task
, this->options_
.output_file_name());
374 Layout
* layout
= this->layout_
;
375 off_t file_size
= layout
->finalize(this->input_objects_
,
380 // Now we know the final size of the output file and we know where
381 // each piece of information goes.
383 if (this->mapfile_
!= NULL
)
385 this->mapfile_
->print_discarded_sections(this->input_objects_
);
386 layout
->print_to_mapfile(this->mapfile_
);
390 if (layout
->incremental_base() == NULL
)
392 of
= new Output_file(parameters
->options().output_file_name());
393 if (this->options_
.oformat_enum() != General_options::OBJECT_FORMAT_ELF
)
394 of
->set_is_temporary();
399 of
= layout
->incremental_base()->output_file();
401 // Apply the incremental relocations for symbols whose values
402 // have changed. We do this before we resize the file and start
403 // writing anything else to it, so that we can read the old
404 // incremental information from the file before (possibly)
406 if (parameters
->incremental_update())
407 layout
->incremental_base()->apply_incremental_relocs(this->symtab_
,
411 of
->resize(file_size
);
414 // Queue up the final set of tasks.
415 gold::queue_final_tasks(this->options_
, this->input_objects_
,
416 this->symtab_
, layout
, workqueue
, of
);
421 Layout::Layout(int number_of_input_files
, Script_options
* script_options
)
422 : number_of_input_files_(number_of_input_files
),
423 script_options_(script_options
),
431 unattached_section_list_(),
432 special_output_list_(),
433 relax_output_list_(),
434 section_headers_(NULL
),
436 relro_segment_(NULL
),
437 interp_segment_(NULL
),
439 symtab_section_(NULL
),
440 symtab_xindex_(NULL
),
441 dynsym_section_(NULL
),
442 dynsym_xindex_(NULL
),
443 dynamic_section_(NULL
),
444 dynamic_symbol_(NULL
),
446 eh_frame_section_(NULL
),
447 eh_frame_data_(NULL
),
448 added_eh_frame_data_(false),
449 eh_frame_hdr_section_(NULL
),
450 gdb_index_data_(NULL
),
451 build_id_note_(NULL
),
452 array_of_hashes_(NULL
),
453 size_of_array_of_hashes_(0),
458 output_file_size_(-1),
459 have_added_input_section_(false),
460 sections_are_attached_(false),
461 input_requires_executable_stack_(false),
462 input_with_gnu_stack_note_(false),
463 input_without_gnu_stack_note_(false),
464 has_static_tls_(false),
465 any_postprocessing_sections_(false),
466 resized_signatures_(false),
467 have_stabstr_section_(false),
468 section_ordering_specified_(false),
469 unique_segment_for_sections_specified_(false),
470 incremental_inputs_(NULL
),
471 record_output_section_data_from_script_(false),
472 script_output_section_data_list_(),
473 segment_states_(NULL
),
474 relaxation_debug_check_(NULL
),
475 section_order_map_(),
476 section_segment_map_(),
477 input_section_position_(),
478 input_section_glob_(),
479 incremental_base_(NULL
),
482 // Make space for more than enough segments for a typical file.
483 // This is just for efficiency--it's OK if we wind up needing more.
484 this->segment_list_
.reserve(12);
486 // We expect two unattached Output_data objects: the file header and
487 // the segment headers.
488 this->special_output_list_
.reserve(2);
490 // Initialize structure needed for an incremental build.
491 if (parameters
->incremental())
492 this->incremental_inputs_
= new Incremental_inputs
;
494 // The section name pool is worth optimizing in all cases, because
495 // it is small, but there are often overlaps due to .rel sections.
496 this->namepool_
.set_optimize();
499 // For incremental links, record the base file to be modified.
502 Layout::set_incremental_base(Incremental_binary
* base
)
504 this->incremental_base_
= base
;
505 this->free_list_
.init(base
->output_file()->filesize(), true);
508 // Hash a key we use to look up an output section mapping.
511 Layout::Hash_key::operator()(const Layout::Key
& k
) const
513 return k
.first
+ k
.second
.first
+ k
.second
.second
;
516 // These are the debug sections that are actually used by gdb.
517 // Currently, we've checked versions of gdb up to and including 7.4.
518 // We only check the part of the name that follows ".debug_" or
521 static const char* gdb_sections
[] =
524 "addr", // Fission extension
525 // "aranges", // not used by gdb as of 7.4
533 // "pubnames", // not used by gdb as of 7.4
534 // "pubtypes", // not used by gdb as of 7.4
539 // This is the minimum set of sections needed for line numbers.
541 static const char* lines_only_debug_sections
[] =
544 // "addr", // Fission extension
545 // "aranges", // not used by gdb as of 7.4
553 // "pubnames", // not used by gdb as of 7.4
554 // "pubtypes", // not used by gdb as of 7.4
559 // These sections are the DWARF fast-lookup tables, and are not needed
560 // when building a .gdb_index section.
562 static const char* gdb_fast_lookup_sections
[] =
569 // Returns whether the given debug section is in the list of
570 // debug-sections-used-by-some-version-of-gdb. SUFFIX is the
571 // portion of the name following ".debug_" or ".zdebug_".
574 is_gdb_debug_section(const char* suffix
)
576 // We can do this faster: binary search or a hashtable. But why bother?
577 for (size_t i
= 0; i
< sizeof(gdb_sections
)/sizeof(*gdb_sections
); ++i
)
578 if (strcmp(suffix
, gdb_sections
[i
]) == 0)
583 // Returns whether the given section is needed for lines-only debugging.
586 is_lines_only_debug_section(const char* suffix
)
588 // We can do this faster: binary search or a hashtable. But why bother?
590 i
< sizeof(lines_only_debug_sections
)/sizeof(*lines_only_debug_sections
);
592 if (strcmp(suffix
, lines_only_debug_sections
[i
]) == 0)
597 // Returns whether the given section is a fast-lookup section that
598 // will not be needed when building a .gdb_index section.
601 is_gdb_fast_lookup_section(const char* suffix
)
603 // We can do this faster: binary search or a hashtable. But why bother?
605 i
< sizeof(gdb_fast_lookup_sections
)/sizeof(*gdb_fast_lookup_sections
);
607 if (strcmp(suffix
, gdb_fast_lookup_sections
[i
]) == 0)
612 // Sometimes we compress sections. This is typically done for
613 // sections that are not part of normal program execution (such as
614 // .debug_* sections), and where the readers of these sections know
615 // how to deal with compressed sections. This routine doesn't say for
616 // certain whether we'll compress -- it depends on commandline options
617 // as well -- just whether this section is a candidate for compression.
618 // (The Output_compressed_section class decides whether to compress
619 // a given section, and picks the name of the compressed section.)
622 is_compressible_debug_section(const char* secname
)
624 return (is_prefix_of(".debug", secname
));
627 // We may see compressed debug sections in input files. Return TRUE
628 // if this is the name of a compressed debug section.
631 is_compressed_debug_section(const char* secname
)
633 return (is_prefix_of(".zdebug", secname
));
636 // Whether to include this section in the link.
638 template<int size
, bool big_endian
>
640 Layout::include_section(Sized_relobj_file
<size
, big_endian
>*, const char* name
,
641 const elfcpp::Shdr
<size
, big_endian
>& shdr
)
643 if (!parameters
->options().relocatable()
644 && (shdr
.get_sh_flags() & elfcpp::SHF_EXCLUDE
))
647 elfcpp::Elf_Word sh_type
= shdr
.get_sh_type();
649 if ((sh_type
>= elfcpp::SHT_LOOS
&& sh_type
<= elfcpp::SHT_HIOS
)
650 || (sh_type
>= elfcpp::SHT_LOPROC
&& sh_type
<= elfcpp::SHT_HIPROC
))
651 return parameters
->target().should_include_section(sh_type
);
655 case elfcpp::SHT_NULL
:
656 case elfcpp::SHT_SYMTAB
:
657 case elfcpp::SHT_DYNSYM
:
658 case elfcpp::SHT_HASH
:
659 case elfcpp::SHT_DYNAMIC
:
660 case elfcpp::SHT_SYMTAB_SHNDX
:
663 case elfcpp::SHT_STRTAB
:
664 // Discard the sections which have special meanings in the ELF
665 // ABI. Keep others (e.g., .stabstr). We could also do this by
666 // checking the sh_link fields of the appropriate sections.
667 return (strcmp(name
, ".dynstr") != 0
668 && strcmp(name
, ".strtab") != 0
669 && strcmp(name
, ".shstrtab") != 0);
671 case elfcpp::SHT_RELA
:
672 case elfcpp::SHT_REL
:
673 case elfcpp::SHT_GROUP
:
674 // If we are emitting relocations these should be handled
676 gold_assert(!parameters
->options().relocatable());
679 case elfcpp::SHT_PROGBITS
:
680 if (parameters
->options().strip_debug()
681 && (shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) == 0)
683 if (is_debug_info_section(name
))
686 if (parameters
->options().strip_debug_non_line()
687 && (shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) == 0)
689 // Debugging sections can only be recognized by name.
690 if (is_prefix_of(".debug_", name
)
691 && !is_lines_only_debug_section(name
+ 7))
693 if (is_prefix_of(".zdebug_", name
)
694 && !is_lines_only_debug_section(name
+ 8))
697 if (parameters
->options().strip_debug_gdb()
698 && (shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) == 0)
700 // Debugging sections can only be recognized by name.
701 if (is_prefix_of(".debug_", name
)
702 && !is_gdb_debug_section(name
+ 7))
704 if (is_prefix_of(".zdebug_", name
)
705 && !is_gdb_debug_section(name
+ 8))
708 if (parameters
->options().gdb_index()
709 && (shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) == 0)
711 // When building .gdb_index, we can strip .debug_pubnames,
712 // .debug_pubtypes, and .debug_aranges sections.
713 if (is_prefix_of(".debug_", name
)
714 && is_gdb_fast_lookup_section(name
+ 7))
716 if (is_prefix_of(".zdebug_", name
)
717 && is_gdb_fast_lookup_section(name
+ 8))
720 if (parameters
->options().strip_lto_sections()
721 && !parameters
->options().relocatable()
722 && (shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) == 0)
724 // Ignore LTO sections containing intermediate code.
725 if (is_prefix_of(".gnu.lto_", name
))
728 // The GNU linker strips .gnu_debuglink sections, so we do too.
729 // This is a feature used to keep debugging information in
731 if (strcmp(name
, ".gnu_debuglink") == 0)
740 // Return an output section named NAME, or NULL if there is none.
743 Layout::find_output_section(const char* name
) const
745 for (Section_list::const_iterator p
= this->section_list_
.begin();
746 p
!= this->section_list_
.end();
748 if (strcmp((*p
)->name(), name
) == 0)
753 // Return an output segment of type TYPE, with segment flags SET set
754 // and segment flags CLEAR clear. Return NULL if there is none.
757 Layout::find_output_segment(elfcpp::PT type
, elfcpp::Elf_Word set
,
758 elfcpp::Elf_Word clear
) const
760 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
761 p
!= this->segment_list_
.end();
763 if (static_cast<elfcpp::PT
>((*p
)->type()) == type
764 && ((*p
)->flags() & set
) == set
765 && ((*p
)->flags() & clear
) == 0)
770 // When we put a .ctors or .dtors section with more than one word into
771 // a .init_array or .fini_array section, we need to reverse the words
772 // in the .ctors/.dtors section. This is because .init_array executes
773 // constructors front to back, where .ctors executes them back to
774 // front, and vice-versa for .fini_array/.dtors. Although we do want
775 // to remap .ctors/.dtors into .init_array/.fini_array because it can
776 // be more efficient, we don't want to change the order in which
777 // constructors/destructors are run. This set just keeps track of
778 // these sections which need to be reversed. It is only changed by
779 // Layout::layout. It should be a private member of Layout, but that
780 // would require layout.h to #include object.h to get the definition
782 static Unordered_set
<Section_id
, Section_id_hash
> ctors_sections_in_init_array
;
784 // Return whether OBJECT/SHNDX is a .ctors/.dtors section mapped to a
785 // .init_array/.fini_array section.
788 Layout::is_ctors_in_init_array(Relobj
* relobj
, unsigned int shndx
) const
790 return (ctors_sections_in_init_array
.find(Section_id(relobj
, shndx
))
791 != ctors_sections_in_init_array
.end());
794 // Return the output section to use for section NAME with type TYPE
795 // and section flags FLAGS. NAME must be canonicalized in the string
796 // pool, and NAME_KEY is the key. ORDER is where this should appear
797 // in the output sections. IS_RELRO is true for a relro section.
800 Layout::get_output_section(const char* name
, Stringpool::Key name_key
,
801 elfcpp::Elf_Word type
, elfcpp::Elf_Xword flags
,
802 Output_section_order order
, bool is_relro
)
804 elfcpp::Elf_Word lookup_type
= type
;
806 // For lookup purposes, treat INIT_ARRAY, FINI_ARRAY, and
807 // PREINIT_ARRAY like PROGBITS. This ensures that we combine
808 // .init_array, .fini_array, and .preinit_array sections by name
809 // whatever their type in the input file. We do this because the
810 // types are not always right in the input files.
811 if (lookup_type
== elfcpp::SHT_INIT_ARRAY
812 || lookup_type
== elfcpp::SHT_FINI_ARRAY
813 || lookup_type
== elfcpp::SHT_PREINIT_ARRAY
)
814 lookup_type
= elfcpp::SHT_PROGBITS
;
816 elfcpp::Elf_Xword lookup_flags
= flags
;
818 // Ignoring SHF_WRITE and SHF_EXECINSTR here means that we combine
819 // read-write with read-only sections. Some other ELF linkers do
820 // not do this. FIXME: Perhaps there should be an option
822 lookup_flags
&= ~(elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
);
824 const Key
key(name_key
, std::make_pair(lookup_type
, lookup_flags
));
825 const std::pair
<Key
, Output_section
*> v(key
, NULL
);
826 std::pair
<Section_name_map::iterator
, bool> ins(
827 this->section_name_map_
.insert(v
));
830 return ins
.first
->second
;
833 // This is the first time we've seen this name/type/flags
834 // combination. For compatibility with the GNU linker, we
835 // combine sections with contents and zero flags with sections
836 // with non-zero flags. This is a workaround for cases where
837 // assembler code forgets to set section flags. FIXME: Perhaps
838 // there should be an option to control this.
839 Output_section
* os
= NULL
;
841 if (lookup_type
== elfcpp::SHT_PROGBITS
)
845 Output_section
* same_name
= this->find_output_section(name
);
846 if (same_name
!= NULL
847 && (same_name
->type() == elfcpp::SHT_PROGBITS
848 || same_name
->type() == elfcpp::SHT_INIT_ARRAY
849 || same_name
->type() == elfcpp::SHT_FINI_ARRAY
850 || same_name
->type() == elfcpp::SHT_PREINIT_ARRAY
)
851 && (same_name
->flags() & elfcpp::SHF_TLS
) == 0)
854 else if ((flags
& elfcpp::SHF_TLS
) == 0)
856 elfcpp::Elf_Xword zero_flags
= 0;
857 const Key
zero_key(name_key
, std::make_pair(lookup_type
,
859 Section_name_map::iterator p
=
860 this->section_name_map_
.find(zero_key
);
861 if (p
!= this->section_name_map_
.end())
867 os
= this->make_output_section(name
, type
, flags
, order
, is_relro
);
869 ins
.first
->second
= os
;
874 // Returns TRUE iff NAME (an input section from RELOBJ) will
875 // be mapped to an output section that should be KEPT.
878 Layout::keep_input_section(const Relobj
* relobj
, const char* name
)
880 if (! this->script_options_
->saw_sections_clause())
883 Script_sections
* ss
= this->script_options_
->script_sections();
884 const char* file_name
= relobj
== NULL
? NULL
: relobj
->name().c_str();
885 Output_section
** output_section_slot
;
886 Script_sections::Section_type script_section_type
;
889 name
= ss
->output_section_name(file_name
, name
, &output_section_slot
,
890 &script_section_type
, &keep
);
891 return name
!= NULL
&& keep
;
894 // Clear the input section flags that should not be copied to the
898 Layout::get_output_section_flags(elfcpp::Elf_Xword input_section_flags
)
900 // Some flags in the input section should not be automatically
901 // copied to the output section.
902 input_section_flags
&= ~ (elfcpp::SHF_INFO_LINK
905 | elfcpp::SHF_STRINGS
);
907 // We only clear the SHF_LINK_ORDER flag in for
908 // a non-relocatable link.
909 if (!parameters
->options().relocatable())
910 input_section_flags
&= ~elfcpp::SHF_LINK_ORDER
;
912 return input_section_flags
;
915 // Pick the output section to use for section NAME, in input file
916 // RELOBJ, with type TYPE and flags FLAGS. RELOBJ may be NULL for a
917 // linker created section. IS_INPUT_SECTION is true if we are
918 // choosing an output section for an input section found in a input
919 // file. ORDER is where this section should appear in the output
920 // sections. IS_RELRO is true for a relro section. This will return
921 // NULL if the input section should be discarded.
924 Layout::choose_output_section(const Relobj
* relobj
, const char* name
,
925 elfcpp::Elf_Word type
, elfcpp::Elf_Xword flags
,
926 bool is_input_section
, Output_section_order order
,
929 // We should not see any input sections after we have attached
930 // sections to segments.
931 gold_assert(!is_input_section
|| !this->sections_are_attached_
);
933 flags
= this->get_output_section_flags(flags
);
935 if (this->script_options_
->saw_sections_clause())
937 // We are using a SECTIONS clause, so the output section is
938 // chosen based only on the name.
940 Script_sections
* ss
= this->script_options_
->script_sections();
941 const char* file_name
= relobj
== NULL
? NULL
: relobj
->name().c_str();
942 Output_section
** output_section_slot
;
943 Script_sections::Section_type script_section_type
;
944 const char* orig_name
= name
;
946 name
= ss
->output_section_name(file_name
, name
, &output_section_slot
,
947 &script_section_type
, &keep
);
951 gold_debug(DEBUG_SCRIPT
, _("Unable to create output section '%s' "
952 "because it is not allowed by the "
953 "SECTIONS clause of the linker script"),
955 // The SECTIONS clause says to discard this input section.
959 // We can only handle script section types ST_NONE and ST_NOLOAD.
960 switch (script_section_type
)
962 case Script_sections::ST_NONE
:
964 case Script_sections::ST_NOLOAD
:
965 flags
&= elfcpp::SHF_ALLOC
;
971 // If this is an orphan section--one not mentioned in the linker
972 // script--then OUTPUT_SECTION_SLOT will be NULL, and we do the
973 // default processing below.
975 if (output_section_slot
!= NULL
)
977 if (*output_section_slot
!= NULL
)
979 (*output_section_slot
)->update_flags_for_input_section(flags
);
980 return *output_section_slot
;
983 // We don't put sections found in the linker script into
984 // SECTION_NAME_MAP_. That keeps us from getting confused
985 // if an orphan section is mapped to a section with the same
986 // name as one in the linker script.
988 name
= this->namepool_
.add(name
, false, NULL
);
990 Output_section
* os
= this->make_output_section(name
, type
, flags
,
993 os
->set_found_in_sections_clause();
995 // Special handling for NOLOAD sections.
996 if (script_section_type
== Script_sections::ST_NOLOAD
)
1000 // The constructor of Output_section sets addresses of non-ALLOC
1001 // sections to 0 by default. We don't want that for NOLOAD
1002 // sections even if they have no SHF_ALLOC flag.
1003 if ((os
->flags() & elfcpp::SHF_ALLOC
) == 0
1004 && os
->is_address_valid())
1006 gold_assert(os
->address() == 0
1007 && !os
->is_offset_valid()
1008 && !os
->is_data_size_valid());
1009 os
->reset_address_and_file_offset();
1013 *output_section_slot
= os
;
1018 // FIXME: Handle SHF_OS_NONCONFORMING somewhere.
1020 size_t len
= strlen(name
);
1021 char* uncompressed_name
= NULL
;
1023 // Compressed debug sections should be mapped to the corresponding
1024 // uncompressed section.
1025 if (is_compressed_debug_section(name
))
1027 uncompressed_name
= new char[len
];
1028 uncompressed_name
[0] = '.';
1029 gold_assert(name
[0] == '.' && name
[1] == 'z');
1030 strncpy(&uncompressed_name
[1], &name
[2], len
- 2);
1031 uncompressed_name
[len
- 1] = '\0';
1033 name
= uncompressed_name
;
1036 // Turn NAME from the name of the input section into the name of the
1038 if (is_input_section
1039 && !this->script_options_
->saw_sections_clause()
1040 && !parameters
->options().relocatable())
1042 const char *orig_name
= name
;
1043 name
= parameters
->target().output_section_name(relobj
, name
, &len
);
1045 name
= Layout::output_section_name(relobj
, orig_name
, &len
);
1048 Stringpool::Key name_key
;
1049 name
= this->namepool_
.add_with_length(name
, len
, true, &name_key
);
1051 if (uncompressed_name
!= NULL
)
1052 delete[] uncompressed_name
;
1054 // Find or make the output section. The output section is selected
1055 // based on the section name, type, and flags.
1056 return this->get_output_section(name
, name_key
, type
, flags
, order
, is_relro
);
1059 // For incremental links, record the initial fixed layout of a section
1060 // from the base file, and return a pointer to the Output_section.
1062 template<int size
, bool big_endian
>
1064 Layout::init_fixed_output_section(const char* name
,
1065 elfcpp::Shdr
<size
, big_endian
>& shdr
)
1067 unsigned int sh_type
= shdr
.get_sh_type();
1069 // We preserve the layout of PROGBITS, NOBITS, INIT_ARRAY, FINI_ARRAY,
1070 // PRE_INIT_ARRAY, and NOTE sections.
1071 // All others will be created from scratch and reallocated.
1072 if (!can_incremental_update(sh_type
))
1075 // If we're generating a .gdb_index section, we need to regenerate
1077 if (parameters
->options().gdb_index()
1078 && sh_type
== elfcpp::SHT_PROGBITS
1079 && strcmp(name
, ".gdb_index") == 0)
1082 typename
elfcpp::Elf_types
<size
>::Elf_Addr sh_addr
= shdr
.get_sh_addr();
1083 typename
elfcpp::Elf_types
<size
>::Elf_Off sh_offset
= shdr
.get_sh_offset();
1084 typename
elfcpp::Elf_types
<size
>::Elf_WXword sh_size
= shdr
.get_sh_size();
1085 typename
elfcpp::Elf_types
<size
>::Elf_WXword sh_flags
= shdr
.get_sh_flags();
1086 typename
elfcpp::Elf_types
<size
>::Elf_WXword sh_addralign
=
1087 shdr
.get_sh_addralign();
1089 // Make the output section.
1090 Stringpool::Key name_key
;
1091 name
= this->namepool_
.add(name
, true, &name_key
);
1092 Output_section
* os
= this->get_output_section(name
, name_key
, sh_type
,
1093 sh_flags
, ORDER_INVALID
, false);
1094 os
->set_fixed_layout(sh_addr
, sh_offset
, sh_size
, sh_addralign
);
1095 if (sh_type
!= elfcpp::SHT_NOBITS
)
1096 this->free_list_
.remove(sh_offset
, sh_offset
+ sh_size
);
1100 // Return the index by which an input section should be ordered. This
1101 // is used to sort some .text sections, for compatibility with GNU ld.
1104 Layout::special_ordering_of_input_section(const char* name
)
1106 // The GNU linker has some special handling for some sections that
1107 // wind up in the .text section. Sections that start with these
1108 // prefixes must appear first, and must appear in the order listed
1110 static const char* const text_section_sort
[] =
1119 i
< sizeof(text_section_sort
) / sizeof(text_section_sort
[0]);
1121 if (is_prefix_of(text_section_sort
[i
], name
))
1127 // Return the output section to use for input section SHNDX, with name
1128 // NAME, with header HEADER, from object OBJECT. RELOC_SHNDX is the
1129 // index of a relocation section which applies to this section, or 0
1130 // if none, or -1U if more than one. RELOC_TYPE is the type of the
1131 // relocation section if there is one. Set *OFF to the offset of this
1132 // input section without the output section. Return NULL if the
1133 // section should be discarded. Set *OFF to -1 if the section
1134 // contents should not be written directly to the output file, but
1135 // will instead receive special handling.
1137 template<int size
, bool big_endian
>
1139 Layout::layout(Sized_relobj_file
<size
, big_endian
>* object
, unsigned int shndx
,
1140 const char* name
, const elfcpp::Shdr
<size
, big_endian
>& shdr
,
1141 unsigned int reloc_shndx
, unsigned int, off_t
* off
)
1145 if (!this->include_section(object
, name
, shdr
))
1148 elfcpp::Elf_Word sh_type
= shdr
.get_sh_type();
1150 // In a relocatable link a grouped section must not be combined with
1151 // any other sections.
1153 if (parameters
->options().relocatable()
1154 && (shdr
.get_sh_flags() & elfcpp::SHF_GROUP
) != 0)
1156 name
= this->namepool_
.add(name
, true, NULL
);
1157 os
= this->make_output_section(name
, sh_type
, shdr
.get_sh_flags(),
1158 ORDER_INVALID
, false);
1162 // Plugins can choose to place one or more subsets of sections in
1163 // unique segments and this is done by mapping these section subsets
1164 // to unique output sections. Check if this section needs to be
1165 // remapped to a unique output section.
1166 Section_segment_map::iterator it
1167 = this->section_segment_map_
.find(Const_section_id(object
, shndx
));
1168 if (it
== this->section_segment_map_
.end())
1170 os
= this->choose_output_section(object
, name
, sh_type
,
1171 shdr
.get_sh_flags(), true,
1172 ORDER_INVALID
, false);
1176 // We know the name of the output section, directly call
1177 // get_output_section here by-passing choose_output_section.
1178 elfcpp::Elf_Xword flags
1179 = this->get_output_section_flags(shdr
.get_sh_flags());
1181 const char* os_name
= it
->second
->name
;
1182 Stringpool::Key name_key
;
1183 os_name
= this->namepool_
.add(os_name
, true, &name_key
);
1184 os
= this->get_output_section(os_name
, name_key
, sh_type
, flags
,
1185 ORDER_INVALID
, false);
1186 if (!os
->is_unique_segment())
1188 os
->set_is_unique_segment();
1189 os
->set_extra_segment_flags(it
->second
->flags
);
1190 os
->set_segment_alignment(it
->second
->align
);
1197 // By default the GNU linker sorts input sections whose names match
1198 // .ctors.*, .dtors.*, .init_array.*, or .fini_array.*. The
1199 // sections are sorted by name. This is used to implement
1200 // constructor priority ordering. We are compatible. When we put
1201 // .ctor sections in .init_array and .dtor sections in .fini_array,
1202 // we must also sort plain .ctor and .dtor sections.
1203 if (!this->script_options_
->saw_sections_clause()
1204 && !parameters
->options().relocatable()
1205 && (is_prefix_of(".ctors.", name
)
1206 || is_prefix_of(".dtors.", name
)
1207 || is_prefix_of(".init_array.", name
)
1208 || is_prefix_of(".fini_array.", name
)
1209 || (parameters
->options().ctors_in_init_array()
1210 && (strcmp(name
, ".ctors") == 0
1211 || strcmp(name
, ".dtors") == 0))))
1212 os
->set_must_sort_attached_input_sections();
1214 // By default the GNU linker sorts some special text sections ahead
1215 // of others. We are compatible.
1216 if (parameters
->options().text_reorder()
1217 && !this->script_options_
->saw_sections_clause()
1218 && !this->is_section_ordering_specified()
1219 && !parameters
->options().relocatable()
1220 && Layout::special_ordering_of_input_section(name
) >= 0)
1221 os
->set_must_sort_attached_input_sections();
1223 // If this is a .ctors or .ctors.* section being mapped to a
1224 // .init_array section, or a .dtors or .dtors.* section being mapped
1225 // to a .fini_array section, we will need to reverse the words if
1226 // there is more than one. Record this section for later. See
1227 // ctors_sections_in_init_array above.
1228 if (!this->script_options_
->saw_sections_clause()
1229 && !parameters
->options().relocatable()
1230 && shdr
.get_sh_size() > size
/ 8
1231 && (((strcmp(name
, ".ctors") == 0
1232 || is_prefix_of(".ctors.", name
))
1233 && strcmp(os
->name(), ".init_array") == 0)
1234 || ((strcmp(name
, ".dtors") == 0
1235 || is_prefix_of(".dtors.", name
))
1236 && strcmp(os
->name(), ".fini_array") == 0)))
1237 ctors_sections_in_init_array
.insert(Section_id(object
, shndx
));
1239 // FIXME: Handle SHF_LINK_ORDER somewhere.
1241 elfcpp::Elf_Xword orig_flags
= os
->flags();
1243 *off
= os
->add_input_section(this, object
, shndx
, name
, shdr
, reloc_shndx
,
1244 this->script_options_
->saw_sections_clause());
1246 // If the flags changed, we may have to change the order.
1247 if ((orig_flags
& elfcpp::SHF_ALLOC
) != 0)
1249 orig_flags
&= (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
);
1250 elfcpp::Elf_Xword new_flags
=
1251 os
->flags() & (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
);
1252 if (orig_flags
!= new_flags
)
1253 os
->set_order(this->default_section_order(os
, false));
1256 this->have_added_input_section_
= true;
1261 // Maps section SECN to SEGMENT s.
1263 Layout::insert_section_segment_map(Const_section_id secn
,
1264 Unique_segment_info
*s
)
1266 gold_assert(this->unique_segment_for_sections_specified_
);
1267 this->section_segment_map_
[secn
] = s
;
1270 // Handle a relocation section when doing a relocatable link.
1272 template<int size
, bool big_endian
>
1274 Layout::layout_reloc(Sized_relobj_file
<size
, big_endian
>* object
,
1276 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
1277 Output_section
* data_section
,
1278 Relocatable_relocs
* rr
)
1280 gold_assert(parameters
->options().relocatable()
1281 || parameters
->options().emit_relocs());
1283 int sh_type
= shdr
.get_sh_type();
1286 if (sh_type
== elfcpp::SHT_REL
)
1288 else if (sh_type
== elfcpp::SHT_RELA
)
1292 name
+= data_section
->name();
1294 // In a relocatable link relocs for a grouped section must not be
1295 // combined with other reloc sections.
1297 if (!parameters
->options().relocatable()
1298 || (data_section
->flags() & elfcpp::SHF_GROUP
) == 0)
1299 os
= this->choose_output_section(object
, name
.c_str(), sh_type
,
1300 shdr
.get_sh_flags(), false,
1301 ORDER_INVALID
, false);
1304 const char* n
= this->namepool_
.add(name
.c_str(), true, NULL
);
1305 os
= this->make_output_section(n
, sh_type
, shdr
.get_sh_flags(),
1306 ORDER_INVALID
, false);
1309 os
->set_should_link_to_symtab();
1310 os
->set_info_section(data_section
);
1312 Output_section_data
* posd
;
1313 if (sh_type
== elfcpp::SHT_REL
)
1315 os
->set_entsize(elfcpp::Elf_sizes
<size
>::rel_size
);
1316 posd
= new Output_relocatable_relocs
<elfcpp::SHT_REL
,
1320 else if (sh_type
== elfcpp::SHT_RELA
)
1322 os
->set_entsize(elfcpp::Elf_sizes
<size
>::rela_size
);
1323 posd
= new Output_relocatable_relocs
<elfcpp::SHT_RELA
,
1330 os
->add_output_section_data(posd
);
1331 rr
->set_output_data(posd
);
1336 // Handle a group section when doing a relocatable link.
1338 template<int size
, bool big_endian
>
1340 Layout::layout_group(Symbol_table
* symtab
,
1341 Sized_relobj_file
<size
, big_endian
>* object
,
1343 const char* group_section_name
,
1344 const char* signature
,
1345 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
1346 elfcpp::Elf_Word flags
,
1347 std::vector
<unsigned int>* shndxes
)
1349 gold_assert(parameters
->options().relocatable());
1350 gold_assert(shdr
.get_sh_type() == elfcpp::SHT_GROUP
);
1351 group_section_name
= this->namepool_
.add(group_section_name
, true, NULL
);
1352 Output_section
* os
= this->make_output_section(group_section_name
,
1354 shdr
.get_sh_flags(),
1355 ORDER_INVALID
, false);
1357 // We need to find a symbol with the signature in the symbol table.
1358 // If we don't find one now, we need to look again later.
1359 Symbol
* sym
= symtab
->lookup(signature
, NULL
);
1361 os
->set_info_symndx(sym
);
1364 // Reserve some space to minimize reallocations.
1365 if (this->group_signatures_
.empty())
1366 this->group_signatures_
.reserve(this->number_of_input_files_
* 16);
1368 // We will wind up using a symbol whose name is the signature.
1369 // So just put the signature in the symbol name pool to save it.
1370 signature
= symtab
->canonicalize_name(signature
);
1371 this->group_signatures_
.push_back(Group_signature(os
, signature
));
1374 os
->set_should_link_to_symtab();
1377 section_size_type entry_count
=
1378 convert_to_section_size_type(shdr
.get_sh_size() / 4);
1379 Output_section_data
* posd
=
1380 new Output_data_group
<size
, big_endian
>(object
, entry_count
, flags
,
1382 os
->add_output_section_data(posd
);
1385 // Special GNU handling of sections name .eh_frame. They will
1386 // normally hold exception frame data as defined by the C++ ABI
1387 // (http://codesourcery.com/cxx-abi/).
1389 template<int size
, bool big_endian
>
1391 Layout::layout_eh_frame(Sized_relobj_file
<size
, big_endian
>* object
,
1392 const unsigned char* symbols
,
1394 const unsigned char* symbol_names
,
1395 off_t symbol_names_size
,
1397 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
1398 unsigned int reloc_shndx
, unsigned int reloc_type
,
1401 gold_assert(shdr
.get_sh_type() == elfcpp::SHT_PROGBITS
1402 || shdr
.get_sh_type() == elfcpp::SHT_X86_64_UNWIND
);
1403 gold_assert((shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) != 0);
1405 Output_section
* os
= this->make_eh_frame_section(object
);
1409 gold_assert(this->eh_frame_section_
== os
);
1411 elfcpp::Elf_Xword orig_flags
= os
->flags();
1413 if (!parameters
->incremental()
1414 && this->eh_frame_data_
->add_ehframe_input_section(object
,
1423 os
->update_flags_for_input_section(shdr
.get_sh_flags());
1425 // A writable .eh_frame section is a RELRO section.
1426 if ((orig_flags
& (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
))
1427 != (os
->flags() & (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
)))
1430 os
->set_order(ORDER_RELRO
);
1433 // We found a .eh_frame section we are going to optimize, so now
1434 // we can add the set of optimized sections to the output
1435 // section. We need to postpone adding this until we've found a
1436 // section we can optimize so that the .eh_frame section in
1437 // crtbegin.o winds up at the start of the output section.
1438 if (!this->added_eh_frame_data_
)
1440 os
->add_output_section_data(this->eh_frame_data_
);
1441 this->added_eh_frame_data_
= true;
1447 // We couldn't handle this .eh_frame section for some reason.
1448 // Add it as a normal section.
1449 bool saw_sections_clause
= this->script_options_
->saw_sections_clause();
1450 *off
= os
->add_input_section(this, object
, shndx
, ".eh_frame", shdr
,
1451 reloc_shndx
, saw_sections_clause
);
1452 this->have_added_input_section_
= true;
1454 if ((orig_flags
& (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
))
1455 != (os
->flags() & (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
)))
1456 os
->set_order(this->default_section_order(os
, false));
1462 // Create and return the magic .eh_frame section. Create
1463 // .eh_frame_hdr also if appropriate. OBJECT is the object with the
1464 // input .eh_frame section; it may be NULL.
1467 Layout::make_eh_frame_section(const Relobj
* object
)
1469 // FIXME: On x86_64, this could use SHT_X86_64_UNWIND rather than
1471 Output_section
* os
= this->choose_output_section(object
, ".eh_frame",
1472 elfcpp::SHT_PROGBITS
,
1473 elfcpp::SHF_ALLOC
, false,
1474 ORDER_EHFRAME
, false);
1478 if (this->eh_frame_section_
== NULL
)
1480 this->eh_frame_section_
= os
;
1481 this->eh_frame_data_
= new Eh_frame();
1483 // For incremental linking, we do not optimize .eh_frame sections
1484 // or create a .eh_frame_hdr section.
1485 if (parameters
->options().eh_frame_hdr() && !parameters
->incremental())
1487 Output_section
* hdr_os
=
1488 this->choose_output_section(NULL
, ".eh_frame_hdr",
1489 elfcpp::SHT_PROGBITS
,
1490 elfcpp::SHF_ALLOC
, false,
1491 ORDER_EHFRAME
, false);
1495 Eh_frame_hdr
* hdr_posd
= new Eh_frame_hdr(os
,
1496 this->eh_frame_data_
);
1497 hdr_os
->add_output_section_data(hdr_posd
);
1499 hdr_os
->set_after_input_sections();
1501 if (!this->script_options_
->saw_phdrs_clause())
1503 Output_segment
* hdr_oseg
;
1504 hdr_oseg
= this->make_output_segment(elfcpp::PT_GNU_EH_FRAME
,
1506 hdr_oseg
->add_output_section_to_nonload(hdr_os
,
1510 this->eh_frame_data_
->set_eh_frame_hdr(hdr_posd
);
1518 // Add an exception frame for a PLT. This is called from target code.
1521 Layout::add_eh_frame_for_plt(Output_data
* plt
, const unsigned char* cie_data
,
1522 size_t cie_length
, const unsigned char* fde_data
,
1525 if (parameters
->incremental())
1527 // FIXME: Maybe this could work some day....
1530 Output_section
* os
= this->make_eh_frame_section(NULL
);
1533 this->eh_frame_data_
->add_ehframe_for_plt(plt
, cie_data
, cie_length
,
1534 fde_data
, fde_length
);
1535 if (!this->added_eh_frame_data_
)
1537 os
->add_output_section_data(this->eh_frame_data_
);
1538 this->added_eh_frame_data_
= true;
1542 // Scan a .debug_info or .debug_types section, and add summary
1543 // information to the .gdb_index section.
1545 template<int size
, bool big_endian
>
1547 Layout::add_to_gdb_index(bool is_type_unit
,
1548 Sized_relobj
<size
, big_endian
>* object
,
1549 const unsigned char* symbols
,
1552 unsigned int reloc_shndx
,
1553 unsigned int reloc_type
)
1555 if (this->gdb_index_data_
== NULL
)
1557 Output_section
* os
= this->choose_output_section(NULL
, ".gdb_index",
1558 elfcpp::SHT_PROGBITS
, 0,
1559 false, ORDER_INVALID
,
1564 this->gdb_index_data_
= new Gdb_index(os
);
1565 os
->add_output_section_data(this->gdb_index_data_
);
1566 os
->set_after_input_sections();
1569 this->gdb_index_data_
->scan_debug_info(is_type_unit
, object
, symbols
,
1570 symbols_size
, shndx
, reloc_shndx
,
1574 // Add POSD to an output section using NAME, TYPE, and FLAGS. Return
1575 // the output section.
1578 Layout::add_output_section_data(const char* name
, elfcpp::Elf_Word type
,
1579 elfcpp::Elf_Xword flags
,
1580 Output_section_data
* posd
,
1581 Output_section_order order
, bool is_relro
)
1583 Output_section
* os
= this->choose_output_section(NULL
, name
, type
, flags
,
1584 false, order
, is_relro
);
1586 os
->add_output_section_data(posd
);
1590 // Map section flags to segment flags.
1593 Layout::section_flags_to_segment(elfcpp::Elf_Xword flags
)
1595 elfcpp::Elf_Word ret
= elfcpp::PF_R
;
1596 if ((flags
& elfcpp::SHF_WRITE
) != 0)
1597 ret
|= elfcpp::PF_W
;
1598 if ((flags
& elfcpp::SHF_EXECINSTR
) != 0)
1599 ret
|= elfcpp::PF_X
;
1603 // Make a new Output_section, and attach it to segments as
1604 // appropriate. ORDER is the order in which this section should
1605 // appear in the output segment. IS_RELRO is true if this is a relro
1606 // (read-only after relocations) section.
1609 Layout::make_output_section(const char* name
, elfcpp::Elf_Word type
,
1610 elfcpp::Elf_Xword flags
,
1611 Output_section_order order
, bool is_relro
)
1614 if ((flags
& elfcpp::SHF_ALLOC
) == 0
1615 && strcmp(parameters
->options().compress_debug_sections(), "none") != 0
1616 && is_compressible_debug_section(name
))
1617 os
= new Output_compressed_section(¶meters
->options(), name
, type
,
1619 else if ((flags
& elfcpp::SHF_ALLOC
) == 0
1620 && parameters
->options().strip_debug_non_line()
1621 && strcmp(".debug_abbrev", name
) == 0)
1623 os
= this->debug_abbrev_
= new Output_reduced_debug_abbrev_section(
1625 if (this->debug_info_
)
1626 this->debug_info_
->set_abbreviations(this->debug_abbrev_
);
1628 else if ((flags
& elfcpp::SHF_ALLOC
) == 0
1629 && parameters
->options().strip_debug_non_line()
1630 && strcmp(".debug_info", name
) == 0)
1632 os
= this->debug_info_
= new Output_reduced_debug_info_section(
1634 if (this->debug_abbrev_
)
1635 this->debug_info_
->set_abbreviations(this->debug_abbrev_
);
1639 // Sometimes .init_array*, .preinit_array* and .fini_array* do
1640 // not have correct section types. Force them here.
1641 if (type
== elfcpp::SHT_PROGBITS
)
1643 if (is_prefix_of(".init_array", name
))
1644 type
= elfcpp::SHT_INIT_ARRAY
;
1645 else if (is_prefix_of(".preinit_array", name
))
1646 type
= elfcpp::SHT_PREINIT_ARRAY
;
1647 else if (is_prefix_of(".fini_array", name
))
1648 type
= elfcpp::SHT_FINI_ARRAY
;
1651 // FIXME: const_cast is ugly.
1652 Target
* target
= const_cast<Target
*>(¶meters
->target());
1653 os
= target
->make_output_section(name
, type
, flags
);
1656 // With -z relro, we have to recognize the special sections by name.
1657 // There is no other way.
1658 bool is_relro_local
= false;
1659 if (!this->script_options_
->saw_sections_clause()
1660 && parameters
->options().relro()
1661 && (flags
& elfcpp::SHF_ALLOC
) != 0
1662 && (flags
& elfcpp::SHF_WRITE
) != 0)
1664 if (type
== elfcpp::SHT_PROGBITS
)
1666 if ((flags
& elfcpp::SHF_TLS
) != 0)
1668 else if (strcmp(name
, ".data.rel.ro") == 0)
1670 else if (strcmp(name
, ".data.rel.ro.local") == 0)
1673 is_relro_local
= true;
1675 else if (strcmp(name
, ".ctors") == 0
1676 || strcmp(name
, ".dtors") == 0
1677 || strcmp(name
, ".jcr") == 0)
1680 else if (type
== elfcpp::SHT_INIT_ARRAY
1681 || type
== elfcpp::SHT_FINI_ARRAY
1682 || type
== elfcpp::SHT_PREINIT_ARRAY
)
1689 if (order
== ORDER_INVALID
&& (flags
& elfcpp::SHF_ALLOC
) != 0)
1690 order
= this->default_section_order(os
, is_relro_local
);
1692 os
->set_order(order
);
1694 parameters
->target().new_output_section(os
);
1696 this->section_list_
.push_back(os
);
1698 // The GNU linker by default sorts some sections by priority, so we
1699 // do the same. We need to know that this might happen before we
1700 // attach any input sections.
1701 if (!this->script_options_
->saw_sections_clause()
1702 && !parameters
->options().relocatable()
1703 && (strcmp(name
, ".init_array") == 0
1704 || strcmp(name
, ".fini_array") == 0
1705 || (!parameters
->options().ctors_in_init_array()
1706 && (strcmp(name
, ".ctors") == 0
1707 || strcmp(name
, ".dtors") == 0))))
1708 os
->set_may_sort_attached_input_sections();
1710 // The GNU linker by default sorts .text.{unlikely,exit,startup,hot}
1711 // sections before other .text sections. We are compatible. We
1712 // need to know that this might happen before we attach any input
1714 if (parameters
->options().text_reorder()
1715 && !this->script_options_
->saw_sections_clause()
1716 && !this->is_section_ordering_specified()
1717 && !parameters
->options().relocatable()
1718 && strcmp(name
, ".text") == 0)
1719 os
->set_may_sort_attached_input_sections();
1721 // GNU linker sorts section by name with --sort-section=name.
1722 if (strcmp(parameters
->options().sort_section(), "name") == 0)
1723 os
->set_must_sort_attached_input_sections();
1725 // Check for .stab*str sections, as .stab* sections need to link to
1727 if (type
== elfcpp::SHT_STRTAB
1728 && !this->have_stabstr_section_
1729 && strncmp(name
, ".stab", 5) == 0
1730 && strcmp(name
+ strlen(name
) - 3, "str") == 0)
1731 this->have_stabstr_section_
= true;
1733 // During a full incremental link, we add patch space to most
1734 // PROGBITS and NOBITS sections. Flag those that may be
1735 // arbitrarily padded.
1736 if ((type
== elfcpp::SHT_PROGBITS
|| type
== elfcpp::SHT_NOBITS
)
1737 && order
!= ORDER_INTERP
1738 && order
!= ORDER_INIT
1739 && order
!= ORDER_PLT
1740 && order
!= ORDER_FINI
1741 && order
!= ORDER_RELRO_LAST
1742 && order
!= ORDER_NON_RELRO_FIRST
1743 && strcmp(name
, ".eh_frame") != 0
1744 && strcmp(name
, ".ctors") != 0
1745 && strcmp(name
, ".dtors") != 0
1746 && strcmp(name
, ".jcr") != 0)
1748 os
->set_is_patch_space_allowed();
1750 // Certain sections require "holes" to be filled with
1751 // specific fill patterns. These fill patterns may have
1752 // a minimum size, so we must prevent allocations from the
1753 // free list that leave a hole smaller than the minimum.
1754 if (strcmp(name
, ".debug_info") == 0)
1755 os
->set_free_space_fill(new Output_fill_debug_info(false));
1756 else if (strcmp(name
, ".debug_types") == 0)
1757 os
->set_free_space_fill(new Output_fill_debug_info(true));
1758 else if (strcmp(name
, ".debug_line") == 0)
1759 os
->set_free_space_fill(new Output_fill_debug_line());
1762 // If we have already attached the sections to segments, then we
1763 // need to attach this one now. This happens for sections created
1764 // directly by the linker.
1765 if (this->sections_are_attached_
)
1766 this->attach_section_to_segment(¶meters
->target(), os
);
1771 // Return the default order in which a section should be placed in an
1772 // output segment. This function captures a lot of the ideas in
1773 // ld/scripttempl/elf.sc in the GNU linker. Note that the order of a
1774 // linker created section is normally set when the section is created;
1775 // this function is used for input sections.
1777 Output_section_order
1778 Layout::default_section_order(Output_section
* os
, bool is_relro_local
)
1780 gold_assert((os
->flags() & elfcpp::SHF_ALLOC
) != 0);
1781 bool is_write
= (os
->flags() & elfcpp::SHF_WRITE
) != 0;
1782 bool is_execinstr
= (os
->flags() & elfcpp::SHF_EXECINSTR
) != 0;
1783 bool is_bss
= false;
1788 case elfcpp::SHT_PROGBITS
:
1790 case elfcpp::SHT_NOBITS
:
1793 case elfcpp::SHT_RELA
:
1794 case elfcpp::SHT_REL
:
1796 return ORDER_DYNAMIC_RELOCS
;
1798 case elfcpp::SHT_HASH
:
1799 case elfcpp::SHT_DYNAMIC
:
1800 case elfcpp::SHT_SHLIB
:
1801 case elfcpp::SHT_DYNSYM
:
1802 case elfcpp::SHT_GNU_HASH
:
1803 case elfcpp::SHT_GNU_verdef
:
1804 case elfcpp::SHT_GNU_verneed
:
1805 case elfcpp::SHT_GNU_versym
:
1807 return ORDER_DYNAMIC_LINKER
;
1809 case elfcpp::SHT_NOTE
:
1810 return is_write
? ORDER_RW_NOTE
: ORDER_RO_NOTE
;
1813 if ((os
->flags() & elfcpp::SHF_TLS
) != 0)
1814 return is_bss
? ORDER_TLS_BSS
: ORDER_TLS_DATA
;
1816 if (!is_bss
&& !is_write
)
1820 if (strcmp(os
->name(), ".init") == 0)
1822 else if (strcmp(os
->name(), ".fini") == 0)
1825 return is_execinstr
? ORDER_TEXT
: ORDER_READONLY
;
1829 return is_relro_local
? ORDER_RELRO_LOCAL
: ORDER_RELRO
;
1831 if (os
->is_small_section())
1832 return is_bss
? ORDER_SMALL_BSS
: ORDER_SMALL_DATA
;
1833 if (os
->is_large_section())
1834 return is_bss
? ORDER_LARGE_BSS
: ORDER_LARGE_DATA
;
1836 return is_bss
? ORDER_BSS
: ORDER_DATA
;
1839 // Attach output sections to segments. This is called after we have
1840 // seen all the input sections.
1843 Layout::attach_sections_to_segments(const Target
* target
)
1845 for (Section_list::iterator p
= this->section_list_
.begin();
1846 p
!= this->section_list_
.end();
1848 this->attach_section_to_segment(target
, *p
);
1850 this->sections_are_attached_
= true;
1853 // Attach an output section to a segment.
1856 Layout::attach_section_to_segment(const Target
* target
, Output_section
* os
)
1858 if ((os
->flags() & elfcpp::SHF_ALLOC
) == 0)
1859 this->unattached_section_list_
.push_back(os
);
1861 this->attach_allocated_section_to_segment(target
, os
);
1864 // Attach an allocated output section to a segment.
1867 Layout::attach_allocated_section_to_segment(const Target
* target
,
1870 elfcpp::Elf_Xword flags
= os
->flags();
1871 gold_assert((flags
& elfcpp::SHF_ALLOC
) != 0);
1873 if (parameters
->options().relocatable())
1876 // If we have a SECTIONS clause, we can't handle the attachment to
1877 // segments until after we've seen all the sections.
1878 if (this->script_options_
->saw_sections_clause())
1881 gold_assert(!this->script_options_
->saw_phdrs_clause());
1883 // This output section goes into a PT_LOAD segment.
1885 elfcpp::Elf_Word seg_flags
= Layout::section_flags_to_segment(flags
);
1887 // If this output section's segment has extra flags that need to be set,
1888 // coming from a linker plugin, do that.
1889 seg_flags
|= os
->extra_segment_flags();
1891 // Check for --section-start.
1893 bool is_address_set
= parameters
->options().section_start(os
->name(), &addr
);
1895 // In general the only thing we really care about for PT_LOAD
1896 // segments is whether or not they are writable or executable,
1897 // so that is how we search for them.
1898 // Large data sections also go into their own PT_LOAD segment.
1899 // People who need segments sorted on some other basis will
1900 // have to use a linker script.
1902 Segment_list::const_iterator p
;
1903 if (!os
->is_unique_segment())
1905 for (p
= this->segment_list_
.begin();
1906 p
!= this->segment_list_
.end();
1909 if ((*p
)->type() != elfcpp::PT_LOAD
)
1911 if ((*p
)->is_unique_segment())
1913 if (!parameters
->options().omagic()
1914 && ((*p
)->flags() & elfcpp::PF_W
) != (seg_flags
& elfcpp::PF_W
))
1916 if ((target
->isolate_execinstr() || parameters
->options().rosegment())
1917 && ((*p
)->flags() & elfcpp::PF_X
) != (seg_flags
& elfcpp::PF_X
))
1919 // If -Tbss was specified, we need to separate the data and BSS
1921 if (parameters
->options().user_set_Tbss())
1923 if ((os
->type() == elfcpp::SHT_NOBITS
)
1924 == (*p
)->has_any_data_sections())
1927 if (os
->is_large_data_section() && !(*p
)->is_large_data_segment())
1932 if ((*p
)->are_addresses_set())
1935 (*p
)->add_initial_output_data(os
);
1936 (*p
)->update_flags_for_output_section(seg_flags
);
1937 (*p
)->set_addresses(addr
, addr
);
1941 (*p
)->add_output_section_to_load(this, os
, seg_flags
);
1946 if (p
== this->segment_list_
.end()
1947 || os
->is_unique_segment())
1949 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_LOAD
,
1951 if (os
->is_large_data_section())
1952 oseg
->set_is_large_data_segment();
1953 oseg
->add_output_section_to_load(this, os
, seg_flags
);
1955 oseg
->set_addresses(addr
, addr
);
1956 // Check if segment should be marked unique. For segments marked
1957 // unique by linker plugins, set the new alignment if specified.
1958 if (os
->is_unique_segment())
1960 oseg
->set_is_unique_segment();
1961 if (os
->segment_alignment() != 0)
1962 oseg
->set_minimum_p_align(os
->segment_alignment());
1966 // If we see a loadable SHT_NOTE section, we create a PT_NOTE
1968 if (os
->type() == elfcpp::SHT_NOTE
)
1970 // See if we already have an equivalent PT_NOTE segment.
1971 for (p
= this->segment_list_
.begin();
1972 p
!= segment_list_
.end();
1975 if ((*p
)->type() == elfcpp::PT_NOTE
1976 && (((*p
)->flags() & elfcpp::PF_W
)
1977 == (seg_flags
& elfcpp::PF_W
)))
1979 (*p
)->add_output_section_to_nonload(os
, seg_flags
);
1984 if (p
== this->segment_list_
.end())
1986 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_NOTE
,
1988 oseg
->add_output_section_to_nonload(os
, seg_flags
);
1992 // If we see a loadable SHF_TLS section, we create a PT_TLS
1993 // segment. There can only be one such segment.
1994 if ((flags
& elfcpp::SHF_TLS
) != 0)
1996 if (this->tls_segment_
== NULL
)
1997 this->make_output_segment(elfcpp::PT_TLS
, seg_flags
);
1998 this->tls_segment_
->add_output_section_to_nonload(os
, seg_flags
);
2001 // If -z relro is in effect, and we see a relro section, we create a
2002 // PT_GNU_RELRO segment. There can only be one such segment.
2003 if (os
->is_relro() && parameters
->options().relro())
2005 gold_assert(seg_flags
== (elfcpp::PF_R
| elfcpp::PF_W
));
2006 if (this->relro_segment_
== NULL
)
2007 this->make_output_segment(elfcpp::PT_GNU_RELRO
, seg_flags
);
2008 this->relro_segment_
->add_output_section_to_nonload(os
, seg_flags
);
2011 // If we see a section named .interp, put it into a PT_INTERP
2012 // segment. This seems broken to me, but this is what GNU ld does,
2013 // and glibc expects it.
2014 if (strcmp(os
->name(), ".interp") == 0
2015 && !this->script_options_
->saw_phdrs_clause())
2017 if (this->interp_segment_
== NULL
)
2018 this->make_output_segment(elfcpp::PT_INTERP
, seg_flags
);
2020 gold_warning(_("multiple '.interp' sections in input files "
2021 "may cause confusing PT_INTERP segment"));
2022 this->interp_segment_
->add_output_section_to_nonload(os
, seg_flags
);
2026 // Make an output section for a script.
2029 Layout::make_output_section_for_script(
2031 Script_sections::Section_type section_type
)
2033 name
= this->namepool_
.add(name
, false, NULL
);
2034 elfcpp::Elf_Xword sh_flags
= elfcpp::SHF_ALLOC
;
2035 if (section_type
== Script_sections::ST_NOLOAD
)
2037 Output_section
* os
= this->make_output_section(name
, elfcpp::SHT_PROGBITS
,
2038 sh_flags
, ORDER_INVALID
,
2040 os
->set_found_in_sections_clause();
2041 if (section_type
== Script_sections::ST_NOLOAD
)
2042 os
->set_is_noload();
2046 // Return the number of segments we expect to see.
2049 Layout::expected_segment_count() const
2051 size_t ret
= this->segment_list_
.size();
2053 // If we didn't see a SECTIONS clause in a linker script, we should
2054 // already have the complete list of segments. Otherwise we ask the
2055 // SECTIONS clause how many segments it expects, and add in the ones
2056 // we already have (PT_GNU_STACK, PT_GNU_EH_FRAME, etc.)
2058 if (!this->script_options_
->saw_sections_clause())
2062 const Script_sections
* ss
= this->script_options_
->script_sections();
2063 return ret
+ ss
->expected_segment_count(this);
2067 // Handle the .note.GNU-stack section at layout time. SEEN_GNU_STACK
2068 // is whether we saw a .note.GNU-stack section in the object file.
2069 // GNU_STACK_FLAGS is the section flags. The flags give the
2070 // protection required for stack memory. We record this in an
2071 // executable as a PT_GNU_STACK segment. If an object file does not
2072 // have a .note.GNU-stack segment, we must assume that it is an old
2073 // object. On some targets that will force an executable stack.
2076 Layout::layout_gnu_stack(bool seen_gnu_stack
, uint64_t gnu_stack_flags
,
2079 if (!seen_gnu_stack
)
2081 this->input_without_gnu_stack_note_
= true;
2082 if (parameters
->options().warn_execstack()
2083 && parameters
->target().is_default_stack_executable())
2084 gold_warning(_("%s: missing .note.GNU-stack section"
2085 " implies executable stack"),
2086 obj
->name().c_str());
2090 this->input_with_gnu_stack_note_
= true;
2091 if ((gnu_stack_flags
& elfcpp::SHF_EXECINSTR
) != 0)
2093 this->input_requires_executable_stack_
= true;
2094 if (parameters
->options().warn_execstack()
2095 || parameters
->options().is_stack_executable())
2096 gold_warning(_("%s: requires executable stack"),
2097 obj
->name().c_str());
2102 // Create automatic note sections.
2105 Layout::create_notes()
2107 this->create_gold_note();
2108 this->create_executable_stack_info();
2109 this->create_build_id();
2112 // Create the dynamic sections which are needed before we read the
2116 Layout::create_initial_dynamic_sections(Symbol_table
* symtab
)
2118 if (parameters
->doing_static_link())
2121 this->dynamic_section_
= this->choose_output_section(NULL
, ".dynamic",
2122 elfcpp::SHT_DYNAMIC
,
2124 | elfcpp::SHF_WRITE
),
2128 // A linker script may discard .dynamic, so check for NULL.
2129 if (this->dynamic_section_
!= NULL
)
2131 this->dynamic_symbol_
=
2132 symtab
->define_in_output_data("_DYNAMIC", NULL
,
2133 Symbol_table::PREDEFINED
,
2134 this->dynamic_section_
, 0, 0,
2135 elfcpp::STT_OBJECT
, elfcpp::STB_LOCAL
,
2136 elfcpp::STV_HIDDEN
, 0, false, false);
2138 this->dynamic_data_
= new Output_data_dynamic(&this->dynpool_
);
2140 this->dynamic_section_
->add_output_section_data(this->dynamic_data_
);
2144 // For each output section whose name can be represented as C symbol,
2145 // define __start and __stop symbols for the section. This is a GNU
2149 Layout::define_section_symbols(Symbol_table
* symtab
)
2151 for (Section_list::const_iterator p
= this->section_list_
.begin();
2152 p
!= this->section_list_
.end();
2155 const char* const name
= (*p
)->name();
2156 if (is_cident(name
))
2158 const std::string
name_string(name
);
2159 const std::string
start_name(cident_section_start_prefix
2161 const std::string
stop_name(cident_section_stop_prefix
2164 symtab
->define_in_output_data(start_name
.c_str(),
2166 Symbol_table::PREDEFINED
,
2172 elfcpp::STV_DEFAULT
,
2174 false, // offset_is_from_end
2175 true); // only_if_ref
2177 symtab
->define_in_output_data(stop_name
.c_str(),
2179 Symbol_table::PREDEFINED
,
2185 elfcpp::STV_DEFAULT
,
2187 true, // offset_is_from_end
2188 true); // only_if_ref
2193 // Define symbols for group signatures.
2196 Layout::define_group_signatures(Symbol_table
* symtab
)
2198 for (Group_signatures::iterator p
= this->group_signatures_
.begin();
2199 p
!= this->group_signatures_
.end();
2202 Symbol
* sym
= symtab
->lookup(p
->signature
, NULL
);
2204 p
->section
->set_info_symndx(sym
);
2207 // Force the name of the group section to the group
2208 // signature, and use the group's section symbol as the
2209 // signature symbol.
2210 if (strcmp(p
->section
->name(), p
->signature
) != 0)
2212 const char* name
= this->namepool_
.add(p
->signature
,
2214 p
->section
->set_name(name
);
2216 p
->section
->set_needs_symtab_index();
2217 p
->section
->set_info_section_symndx(p
->section
);
2221 this->group_signatures_
.clear();
2224 // Find the first read-only PT_LOAD segment, creating one if
2228 Layout::find_first_load_seg(const Target
* target
)
2230 Output_segment
* best
= NULL
;
2231 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
2232 p
!= this->segment_list_
.end();
2235 if ((*p
)->type() == elfcpp::PT_LOAD
2236 && ((*p
)->flags() & elfcpp::PF_R
) != 0
2237 && (parameters
->options().omagic()
2238 || ((*p
)->flags() & elfcpp::PF_W
) == 0)
2239 && (!target
->isolate_execinstr()
2240 || ((*p
)->flags() & elfcpp::PF_X
) == 0))
2242 if (best
== NULL
|| this->segment_precedes(*p
, best
))
2249 gold_assert(!this->script_options_
->saw_phdrs_clause());
2251 Output_segment
* load_seg
= this->make_output_segment(elfcpp::PT_LOAD
,
2256 // Save states of all current output segments. Store saved states
2257 // in SEGMENT_STATES.
2260 Layout::save_segments(Segment_states
* segment_states
)
2262 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
2263 p
!= this->segment_list_
.end();
2266 Output_segment
* segment
= *p
;
2268 Output_segment
* copy
= new Output_segment(*segment
);
2269 (*segment_states
)[segment
] = copy
;
2273 // Restore states of output segments and delete any segment not found in
2277 Layout::restore_segments(const Segment_states
* segment_states
)
2279 // Go through the segment list and remove any segment added in the
2281 this->tls_segment_
= NULL
;
2282 this->relro_segment_
= NULL
;
2283 Segment_list::iterator list_iter
= this->segment_list_
.begin();
2284 while (list_iter
!= this->segment_list_
.end())
2286 Output_segment
* segment
= *list_iter
;
2287 Segment_states::const_iterator states_iter
=
2288 segment_states
->find(segment
);
2289 if (states_iter
!= segment_states
->end())
2291 const Output_segment
* copy
= states_iter
->second
;
2292 // Shallow copy to restore states.
2295 // Also fix up TLS and RELRO segment pointers as appropriate.
2296 if (segment
->type() == elfcpp::PT_TLS
)
2297 this->tls_segment_
= segment
;
2298 else if (segment
->type() == elfcpp::PT_GNU_RELRO
)
2299 this->relro_segment_
= segment
;
2305 list_iter
= this->segment_list_
.erase(list_iter
);
2306 // This is a segment created during section layout. It should be
2307 // safe to remove it since we should have removed all pointers to it.
2313 // Clean up after relaxation so that sections can be laid out again.
2316 Layout::clean_up_after_relaxation()
2318 // Restore the segments to point state just prior to the relaxation loop.
2319 Script_sections
* script_section
= this->script_options_
->script_sections();
2320 script_section
->release_segments();
2321 this->restore_segments(this->segment_states_
);
2323 // Reset section addresses and file offsets
2324 for (Section_list::iterator p
= this->section_list_
.begin();
2325 p
!= this->section_list_
.end();
2328 (*p
)->restore_states();
2330 // If an input section changes size because of relaxation,
2331 // we need to adjust the section offsets of all input sections.
2332 // after such a section.
2333 if ((*p
)->section_offsets_need_adjustment())
2334 (*p
)->adjust_section_offsets();
2336 (*p
)->reset_address_and_file_offset();
2339 // Reset special output object address and file offsets.
2340 for (Data_list::iterator p
= this->special_output_list_
.begin();
2341 p
!= this->special_output_list_
.end();
2343 (*p
)->reset_address_and_file_offset();
2345 // A linker script may have created some output section data objects.
2346 // They are useless now.
2347 for (Output_section_data_list::const_iterator p
=
2348 this->script_output_section_data_list_
.begin();
2349 p
!= this->script_output_section_data_list_
.end();
2352 this->script_output_section_data_list_
.clear();
2354 // Special-case fill output objects are recreated each time through
2355 // the relaxation loop.
2356 this->reset_relax_output();
2360 Layout::reset_relax_output()
2362 for (Data_list::const_iterator p
= this->relax_output_list_
.begin();
2363 p
!= this->relax_output_list_
.end();
2366 this->relax_output_list_
.clear();
2369 // Prepare for relaxation.
2372 Layout::prepare_for_relaxation()
2374 // Create an relaxation debug check if in debugging mode.
2375 if (is_debugging_enabled(DEBUG_RELAXATION
))
2376 this->relaxation_debug_check_
= new Relaxation_debug_check();
2378 // Save segment states.
2379 this->segment_states_
= new Segment_states();
2380 this->save_segments(this->segment_states_
);
2382 for(Section_list::const_iterator p
= this->section_list_
.begin();
2383 p
!= this->section_list_
.end();
2385 (*p
)->save_states();
2387 if (is_debugging_enabled(DEBUG_RELAXATION
))
2388 this->relaxation_debug_check_
->check_output_data_for_reset_values(
2389 this->section_list_
, this->special_output_list_
,
2390 this->relax_output_list_
);
2392 // Also enable recording of output section data from scripts.
2393 this->record_output_section_data_from_script_
= true;
2396 // If the user set the address of the text segment, that may not be
2397 // compatible with putting the segment headers and file headers into
2398 // that segment. For isolate_execinstr() targets, it's the rodata
2399 // segment rather than text where we might put the headers.
2401 load_seg_unusable_for_headers(const Target
* target
)
2403 const General_options
& options
= parameters
->options();
2404 if (target
->isolate_execinstr())
2405 return (options
.user_set_Trodata_segment()
2406 && options
.Trodata_segment() % target
->abi_pagesize() != 0);
2408 return (options
.user_set_Ttext()
2409 && options
.Ttext() % target
->abi_pagesize() != 0);
2412 // Relaxation loop body: If target has no relaxation, this runs only once
2413 // Otherwise, the target relaxation hook is called at the end of
2414 // each iteration. If the hook returns true, it means re-layout of
2415 // section is required.
2417 // The number of segments created by a linking script without a PHDRS
2418 // clause may be affected by section sizes and alignments. There is
2419 // a remote chance that relaxation causes different number of PT_LOAD
2420 // segments are created and sections are attached to different segments.
2421 // Therefore, we always throw away all segments created during section
2422 // layout. In order to be able to restart the section layout, we keep
2423 // a copy of the segment list right before the relaxation loop and use
2424 // that to restore the segments.
2426 // PASS is the current relaxation pass number.
2427 // SYMTAB is a symbol table.
2428 // PLOAD_SEG is the address of a pointer for the load segment.
2429 // PHDR_SEG is a pointer to the PHDR segment.
2430 // SEGMENT_HEADERS points to the output segment header.
2431 // FILE_HEADER points to the output file header.
2432 // PSHNDX is the address to store the output section index.
2435 Layout::relaxation_loop_body(
2438 Symbol_table
* symtab
,
2439 Output_segment
** pload_seg
,
2440 Output_segment
* phdr_seg
,
2441 Output_segment_headers
* segment_headers
,
2442 Output_file_header
* file_header
,
2443 unsigned int* pshndx
)
2445 // If this is not the first iteration, we need to clean up after
2446 // relaxation so that we can lay out the sections again.
2448 this->clean_up_after_relaxation();
2450 // If there is a SECTIONS clause, put all the input sections into
2451 // the required order.
2452 Output_segment
* load_seg
;
2453 if (this->script_options_
->saw_sections_clause())
2454 load_seg
= this->set_section_addresses_from_script(symtab
);
2455 else if (parameters
->options().relocatable())
2458 load_seg
= this->find_first_load_seg(target
);
2460 if (parameters
->options().oformat_enum()
2461 != General_options::OBJECT_FORMAT_ELF
)
2464 if (load_seg_unusable_for_headers(target
))
2470 gold_assert(phdr_seg
== NULL
2472 || this->script_options_
->saw_sections_clause());
2474 // If the address of the load segment we found has been set by
2475 // --section-start rather than by a script, then adjust the VMA and
2476 // LMA downward if possible to include the file and section headers.
2477 uint64_t header_gap
= 0;
2478 if (load_seg
!= NULL
2479 && load_seg
->are_addresses_set()
2480 && !this->script_options_
->saw_sections_clause()
2481 && !parameters
->options().relocatable())
2483 file_header
->finalize_data_size();
2484 segment_headers
->finalize_data_size();
2485 size_t sizeof_headers
= (file_header
->data_size()
2486 + segment_headers
->data_size());
2487 const uint64_t abi_pagesize
= target
->abi_pagesize();
2488 uint64_t hdr_paddr
= load_seg
->paddr() - sizeof_headers
;
2489 hdr_paddr
&= ~(abi_pagesize
- 1);
2490 uint64_t subtract
= load_seg
->paddr() - hdr_paddr
;
2491 if (load_seg
->paddr() < subtract
|| load_seg
->vaddr() < subtract
)
2495 load_seg
->set_addresses(load_seg
->vaddr() - subtract
,
2496 load_seg
->paddr() - subtract
);
2497 header_gap
= subtract
- sizeof_headers
;
2501 // Lay out the segment headers.
2502 if (!parameters
->options().relocatable())
2504 gold_assert(segment_headers
!= NULL
);
2505 if (header_gap
!= 0 && load_seg
!= NULL
)
2507 Output_data_zero_fill
* z
= new Output_data_zero_fill(header_gap
, 1);
2508 load_seg
->add_initial_output_data(z
);
2510 if (load_seg
!= NULL
)
2511 load_seg
->add_initial_output_data(segment_headers
);
2512 if (phdr_seg
!= NULL
)
2513 phdr_seg
->add_initial_output_data(segment_headers
);
2516 // Lay out the file header.
2517 if (load_seg
!= NULL
)
2518 load_seg
->add_initial_output_data(file_header
);
2520 if (this->script_options_
->saw_phdrs_clause()
2521 && !parameters
->options().relocatable())
2523 // Support use of FILEHDRS and PHDRS attachments in a PHDRS
2524 // clause in a linker script.
2525 Script_sections
* ss
= this->script_options_
->script_sections();
2526 ss
->put_headers_in_phdrs(file_header
, segment_headers
);
2529 // We set the output section indexes in set_segment_offsets and
2530 // set_section_indexes.
2533 // Set the file offsets of all the segments, and all the sections
2536 if (!parameters
->options().relocatable())
2537 off
= this->set_segment_offsets(target
, load_seg
, pshndx
);
2539 off
= this->set_relocatable_section_offsets(file_header
, pshndx
);
2541 // Verify that the dummy relaxation does not change anything.
2542 if (is_debugging_enabled(DEBUG_RELAXATION
))
2545 this->relaxation_debug_check_
->read_sections(this->section_list_
);
2547 this->relaxation_debug_check_
->verify_sections(this->section_list_
);
2550 *pload_seg
= load_seg
;
2554 // Search the list of patterns and find the postion of the given section
2555 // name in the output section. If the section name matches a glob
2556 // pattern and a non-glob name, then the non-glob position takes
2557 // precedence. Return 0 if no match is found.
2560 Layout::find_section_order_index(const std::string
& section_name
)
2562 Unordered_map
<std::string
, unsigned int>::iterator map_it
;
2563 map_it
= this->input_section_position_
.find(section_name
);
2564 if (map_it
!= this->input_section_position_
.end())
2565 return map_it
->second
;
2567 // Absolute match failed. Linear search the glob patterns.
2568 std::vector
<std::string
>::iterator it
;
2569 for (it
= this->input_section_glob_
.begin();
2570 it
!= this->input_section_glob_
.end();
2573 if (fnmatch((*it
).c_str(), section_name
.c_str(), FNM_NOESCAPE
) == 0)
2575 map_it
= this->input_section_position_
.find(*it
);
2576 gold_assert(map_it
!= this->input_section_position_
.end());
2577 return map_it
->second
;
2583 // Read the sequence of input sections from the file specified with
2584 // option --section-ordering-file.
2587 Layout::read_layout_from_file()
2589 const char* filename
= parameters
->options().section_ordering_file();
2595 gold_fatal(_("unable to open --section-ordering-file file %s: %s"),
2596 filename
, strerror(errno
));
2598 std::getline(in
, line
); // this chops off the trailing \n, if any
2599 unsigned int position
= 1;
2600 this->set_section_ordering_specified();
2604 if (!line
.empty() && line
[line
.length() - 1] == '\r') // Windows
2605 line
.resize(line
.length() - 1);
2606 // Ignore comments, beginning with '#'
2609 std::getline(in
, line
);
2612 this->input_section_position_
[line
] = position
;
2613 // Store all glob patterns in a vector.
2614 if (is_wildcard_string(line
.c_str()))
2615 this->input_section_glob_
.push_back(line
);
2617 std::getline(in
, line
);
2621 // Finalize the layout. When this is called, we have created all the
2622 // output sections and all the output segments which are based on
2623 // input sections. We have several things to do, and we have to do
2624 // them in the right order, so that we get the right results correctly
2627 // 1) Finalize the list of output segments and create the segment
2630 // 2) Finalize the dynamic symbol table and associated sections.
2632 // 3) Determine the final file offset of all the output segments.
2634 // 4) Determine the final file offset of all the SHF_ALLOC output
2637 // 5) Create the symbol table sections and the section name table
2640 // 6) Finalize the symbol table: set symbol values to their final
2641 // value and make a final determination of which symbols are going
2642 // into the output symbol table.
2644 // 7) Create the section table header.
2646 // 8) Determine the final file offset of all the output sections which
2647 // are not SHF_ALLOC, including the section table header.
2649 // 9) Finalize the ELF file header.
2651 // This function returns the size of the output file.
2654 Layout::finalize(const Input_objects
* input_objects
, Symbol_table
* symtab
,
2655 Target
* target
, const Task
* task
)
2657 target
->finalize_sections(this, input_objects
, symtab
);
2659 this->count_local_symbols(task
, input_objects
);
2661 this->link_stabs_sections();
2663 Output_segment
* phdr_seg
= NULL
;
2664 if (!parameters
->options().relocatable() && !parameters
->doing_static_link())
2666 // There was a dynamic object in the link. We need to create
2667 // some information for the dynamic linker.
2669 // Create the PT_PHDR segment which will hold the program
2671 if (!this->script_options_
->saw_phdrs_clause())
2672 phdr_seg
= this->make_output_segment(elfcpp::PT_PHDR
, elfcpp::PF_R
);
2674 // Create the dynamic symbol table, including the hash table.
2675 Output_section
* dynstr
;
2676 std::vector
<Symbol
*> dynamic_symbols
;
2677 unsigned int local_dynamic_count
;
2678 Versions
versions(*this->script_options()->version_script_info(),
2680 this->create_dynamic_symtab(input_objects
, symtab
, &dynstr
,
2681 &local_dynamic_count
, &dynamic_symbols
,
2684 // Create the .interp section to hold the name of the
2685 // interpreter, and put it in a PT_INTERP segment. Don't do it
2686 // if we saw a .interp section in an input file.
2687 if ((!parameters
->options().shared()
2688 || parameters
->options().dynamic_linker() != NULL
)
2689 && this->interp_segment_
== NULL
)
2690 this->create_interp(target
);
2692 // Finish the .dynamic section to hold the dynamic data, and put
2693 // it in a PT_DYNAMIC segment.
2694 this->finish_dynamic_section(input_objects
, symtab
);
2696 // We should have added everything we need to the dynamic string
2698 this->dynpool_
.set_string_offsets();
2700 // Create the version sections. We can't do this until the
2701 // dynamic string table is complete.
2702 this->create_version_sections(&versions
, symtab
, local_dynamic_count
,
2703 dynamic_symbols
, dynstr
);
2705 // Set the size of the _DYNAMIC symbol. We can't do this until
2706 // after we call create_version_sections.
2707 this->set_dynamic_symbol_size(symtab
);
2710 // Create segment headers.
2711 Output_segment_headers
* segment_headers
=
2712 (parameters
->options().relocatable()
2714 : new Output_segment_headers(this->segment_list_
));
2716 // Lay out the file header.
2717 Output_file_header
* file_header
= new Output_file_header(target
, symtab
,
2720 this->special_output_list_
.push_back(file_header
);
2721 if (segment_headers
!= NULL
)
2722 this->special_output_list_
.push_back(segment_headers
);
2724 // Find approriate places for orphan output sections if we are using
2726 if (this->script_options_
->saw_sections_clause())
2727 this->place_orphan_sections_in_script();
2729 Output_segment
* load_seg
;
2734 // Take a snapshot of the section layout as needed.
2735 if (target
->may_relax())
2736 this->prepare_for_relaxation();
2738 // Run the relaxation loop to lay out sections.
2741 off
= this->relaxation_loop_body(pass
, target
, symtab
, &load_seg
,
2742 phdr_seg
, segment_headers
, file_header
,
2746 while (target
->may_relax()
2747 && target
->relax(pass
, input_objects
, symtab
, this, task
));
2749 // If there is a load segment that contains the file and program headers,
2750 // provide a symbol __ehdr_start pointing there.
2751 // A program can use this to examine itself robustly.
2752 Symbol
*ehdr_start
= symtab
->lookup("__ehdr_start");
2753 if (ehdr_start
!= NULL
&& ehdr_start
->is_predefined())
2755 if (load_seg
!= NULL
)
2756 ehdr_start
->set_output_segment(load_seg
, Symbol::SEGMENT_START
);
2758 ehdr_start
->set_undefined();
2761 // Set the file offsets of all the non-data sections we've seen so
2762 // far which don't have to wait for the input sections. We need
2763 // this in order to finalize local symbols in non-allocated
2765 off
= this->set_section_offsets(off
, BEFORE_INPUT_SECTIONS_PASS
);
2767 // Set the section indexes of all unallocated sections seen so far,
2768 // in case any of them are somehow referenced by a symbol.
2769 shndx
= this->set_section_indexes(shndx
);
2771 // Create the symbol table sections.
2772 this->create_symtab_sections(input_objects
, symtab
, shndx
, &off
);
2773 if (!parameters
->doing_static_link())
2774 this->assign_local_dynsym_offsets(input_objects
);
2776 // Process any symbol assignments from a linker script. This must
2777 // be called after the symbol table has been finalized.
2778 this->script_options_
->finalize_symbols(symtab
, this);
2780 // Create the incremental inputs sections.
2781 if (this->incremental_inputs_
)
2783 this->incremental_inputs_
->finalize();
2784 this->create_incremental_info_sections(symtab
);
2787 // Create the .shstrtab section.
2788 Output_section
* shstrtab_section
= this->create_shstrtab();
2790 // Set the file offsets of the rest of the non-data sections which
2791 // don't have to wait for the input sections.
2792 off
= this->set_section_offsets(off
, BEFORE_INPUT_SECTIONS_PASS
);
2794 // Now that all sections have been created, set the section indexes
2795 // for any sections which haven't been done yet.
2796 shndx
= this->set_section_indexes(shndx
);
2798 // Create the section table header.
2799 this->create_shdrs(shstrtab_section
, &off
);
2801 // If there are no sections which require postprocessing, we can
2802 // handle the section names now, and avoid a resize later.
2803 if (!this->any_postprocessing_sections_
)
2805 off
= this->set_section_offsets(off
,
2806 POSTPROCESSING_SECTIONS_PASS
);
2808 this->set_section_offsets(off
,
2809 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
);
2812 file_header
->set_section_info(this->section_headers_
, shstrtab_section
);
2814 // Now we know exactly where everything goes in the output file
2815 // (except for non-allocated sections which require postprocessing).
2816 Output_data::layout_complete();
2818 this->output_file_size_
= off
;
2823 // Create a note header following the format defined in the ELF ABI.
2824 // NAME is the name, NOTE_TYPE is the type, SECTION_NAME is the name
2825 // of the section to create, DESCSZ is the size of the descriptor.
2826 // ALLOCATE is true if the section should be allocated in memory.
2827 // This returns the new note section. It sets *TRAILING_PADDING to
2828 // the number of trailing zero bytes required.
2831 Layout::create_note(const char* name
, int note_type
,
2832 const char* section_name
, size_t descsz
,
2833 bool allocate
, size_t* trailing_padding
)
2835 // Authorities all agree that the values in a .note field should
2836 // be aligned on 4-byte boundaries for 32-bit binaries. However,
2837 // they differ on what the alignment is for 64-bit binaries.
2838 // The GABI says unambiguously they take 8-byte alignment:
2839 // http://sco.com/developers/gabi/latest/ch5.pheader.html#note_section
2840 // Other documentation says alignment should always be 4 bytes:
2841 // http://www.netbsd.org/docs/kernel/elf-notes.html#note-format
2842 // GNU ld and GNU readelf both support the latter (at least as of
2843 // version 2.16.91), and glibc always generates the latter for
2844 // .note.ABI-tag (as of version 1.6), so that's the one we go with
2846 #ifdef GABI_FORMAT_FOR_DOTNOTE_SECTION // This is not defined by default.
2847 const int size
= parameters
->target().get_size();
2849 const int size
= 32;
2852 // The contents of the .note section.
2853 size_t namesz
= strlen(name
) + 1;
2854 size_t aligned_namesz
= align_address(namesz
, size
/ 8);
2855 size_t aligned_descsz
= align_address(descsz
, size
/ 8);
2857 size_t notehdrsz
= 3 * (size
/ 8) + aligned_namesz
;
2859 unsigned char* buffer
= new unsigned char[notehdrsz
];
2860 memset(buffer
, 0, notehdrsz
);
2862 bool is_big_endian
= parameters
->target().is_big_endian();
2868 elfcpp::Swap
<32, false>::writeval(buffer
, namesz
);
2869 elfcpp::Swap
<32, false>::writeval(buffer
+ 4, descsz
);
2870 elfcpp::Swap
<32, false>::writeval(buffer
+ 8, note_type
);
2874 elfcpp::Swap
<32, true>::writeval(buffer
, namesz
);
2875 elfcpp::Swap
<32, true>::writeval(buffer
+ 4, descsz
);
2876 elfcpp::Swap
<32, true>::writeval(buffer
+ 8, note_type
);
2879 else if (size
== 64)
2883 elfcpp::Swap
<64, false>::writeval(buffer
, namesz
);
2884 elfcpp::Swap
<64, false>::writeval(buffer
+ 8, descsz
);
2885 elfcpp::Swap
<64, false>::writeval(buffer
+ 16, note_type
);
2889 elfcpp::Swap
<64, true>::writeval(buffer
, namesz
);
2890 elfcpp::Swap
<64, true>::writeval(buffer
+ 8, descsz
);
2891 elfcpp::Swap
<64, true>::writeval(buffer
+ 16, note_type
);
2897 memcpy(buffer
+ 3 * (size
/ 8), name
, namesz
);
2899 elfcpp::Elf_Xword flags
= 0;
2900 Output_section_order order
= ORDER_INVALID
;
2903 flags
= elfcpp::SHF_ALLOC
;
2904 order
= ORDER_RO_NOTE
;
2906 Output_section
* os
= this->choose_output_section(NULL
, section_name
,
2908 flags
, false, order
, false);
2912 Output_section_data
* posd
= new Output_data_const_buffer(buffer
, notehdrsz
,
2915 os
->add_output_section_data(posd
);
2917 *trailing_padding
= aligned_descsz
- descsz
;
2922 // For an executable or shared library, create a note to record the
2923 // version of gold used to create the binary.
2926 Layout::create_gold_note()
2928 if (parameters
->options().relocatable()
2929 || parameters
->incremental_update())
2932 std::string desc
= std::string("gold ") + gold::get_version_string();
2934 size_t trailing_padding
;
2935 Output_section
* os
= this->create_note("GNU", elfcpp::NT_GNU_GOLD_VERSION
,
2936 ".note.gnu.gold-version", desc
.size(),
2937 false, &trailing_padding
);
2941 Output_section_data
* posd
= new Output_data_const(desc
, 4);
2942 os
->add_output_section_data(posd
);
2944 if (trailing_padding
> 0)
2946 posd
= new Output_data_zero_fill(trailing_padding
, 0);
2947 os
->add_output_section_data(posd
);
2951 // Record whether the stack should be executable. This can be set
2952 // from the command line using the -z execstack or -z noexecstack
2953 // options. Otherwise, if any input file has a .note.GNU-stack
2954 // section with the SHF_EXECINSTR flag set, the stack should be
2955 // executable. Otherwise, if at least one input file a
2956 // .note.GNU-stack section, and some input file has no .note.GNU-stack
2957 // section, we use the target default for whether the stack should be
2958 // executable. Otherwise, we don't generate a stack note. When
2959 // generating a object file, we create a .note.GNU-stack section with
2960 // the appropriate marking. When generating an executable or shared
2961 // library, we create a PT_GNU_STACK segment.
2964 Layout::create_executable_stack_info()
2966 bool is_stack_executable
;
2967 if (parameters
->options().is_execstack_set())
2968 is_stack_executable
= parameters
->options().is_stack_executable();
2969 else if (!this->input_with_gnu_stack_note_
)
2973 if (this->input_requires_executable_stack_
)
2974 is_stack_executable
= true;
2975 else if (this->input_without_gnu_stack_note_
)
2976 is_stack_executable
=
2977 parameters
->target().is_default_stack_executable();
2979 is_stack_executable
= false;
2982 if (parameters
->options().relocatable())
2984 const char* name
= this->namepool_
.add(".note.GNU-stack", false, NULL
);
2985 elfcpp::Elf_Xword flags
= 0;
2986 if (is_stack_executable
)
2987 flags
|= elfcpp::SHF_EXECINSTR
;
2988 this->make_output_section(name
, elfcpp::SHT_PROGBITS
, flags
,
2989 ORDER_INVALID
, false);
2993 if (this->script_options_
->saw_phdrs_clause())
2995 int flags
= elfcpp::PF_R
| elfcpp::PF_W
;
2996 if (is_stack_executable
)
2997 flags
|= elfcpp::PF_X
;
2998 this->make_output_segment(elfcpp::PT_GNU_STACK
, flags
);
3002 // If --build-id was used, set up the build ID note.
3005 Layout::create_build_id()
3007 if (!parameters
->options().user_set_build_id())
3010 const char* style
= parameters
->options().build_id();
3011 if (strcmp(style
, "none") == 0)
3014 // Set DESCSZ to the size of the note descriptor. When possible,
3015 // set DESC to the note descriptor contents.
3018 if (strcmp(style
, "md5") == 0)
3020 else if ((strcmp(style
, "sha1") == 0) || (strcmp(style
, "tree") == 0))
3022 else if (strcmp(style
, "uuid") == 0)
3024 const size_t uuidsz
= 128 / 8;
3026 char buffer
[uuidsz
];
3027 memset(buffer
, 0, uuidsz
);
3029 int descriptor
= open_descriptor(-1, "/dev/urandom", O_RDONLY
);
3031 gold_error(_("--build-id=uuid failed: could not open /dev/urandom: %s"),
3035 ssize_t got
= ::read(descriptor
, buffer
, uuidsz
);
3036 release_descriptor(descriptor
, true);
3038 gold_error(_("/dev/urandom: read failed: %s"), strerror(errno
));
3039 else if (static_cast<size_t>(got
) != uuidsz
)
3040 gold_error(_("/dev/urandom: expected %zu bytes, got %zd bytes"),
3044 desc
.assign(buffer
, uuidsz
);
3047 else if (strncmp(style
, "0x", 2) == 0)
3050 const char* p
= style
+ 2;
3053 if (hex_p(p
[0]) && hex_p(p
[1]))
3055 char c
= (hex_value(p
[0]) << 4) | hex_value(p
[1]);
3059 else if (*p
== '-' || *p
== ':')
3062 gold_fatal(_("--build-id argument '%s' not a valid hex number"),
3065 descsz
= desc
.size();
3068 gold_fatal(_("unrecognized --build-id argument '%s'"), style
);
3071 size_t trailing_padding
;
3072 Output_section
* os
= this->create_note("GNU", elfcpp::NT_GNU_BUILD_ID
,
3073 ".note.gnu.build-id", descsz
, true,
3080 // We know the value already, so we fill it in now.
3081 gold_assert(desc
.size() == descsz
);
3083 Output_section_data
* posd
= new Output_data_const(desc
, 4);
3084 os
->add_output_section_data(posd
);
3086 if (trailing_padding
!= 0)
3088 posd
= new Output_data_zero_fill(trailing_padding
, 0);
3089 os
->add_output_section_data(posd
);
3094 // We need to compute a checksum after we have completed the
3096 gold_assert(trailing_padding
== 0);
3097 this->build_id_note_
= new Output_data_zero_fill(descsz
, 4);
3098 os
->add_output_section_data(this->build_id_note_
);
3102 // If we have both .stabXX and .stabXXstr sections, then the sh_link
3103 // field of the former should point to the latter. I'm not sure who
3104 // started this, but the GNU linker does it, and some tools depend
3108 Layout::link_stabs_sections()
3110 if (!this->have_stabstr_section_
)
3113 for (Section_list::iterator p
= this->section_list_
.begin();
3114 p
!= this->section_list_
.end();
3117 if ((*p
)->type() != elfcpp::SHT_STRTAB
)
3120 const char* name
= (*p
)->name();
3121 if (strncmp(name
, ".stab", 5) != 0)
3124 size_t len
= strlen(name
);
3125 if (strcmp(name
+ len
- 3, "str") != 0)
3128 std::string
stab_name(name
, len
- 3);
3129 Output_section
* stab_sec
;
3130 stab_sec
= this->find_output_section(stab_name
.c_str());
3131 if (stab_sec
!= NULL
)
3132 stab_sec
->set_link_section(*p
);
3136 // Create .gnu_incremental_inputs and related sections needed
3137 // for the next run of incremental linking to check what has changed.
3140 Layout::create_incremental_info_sections(Symbol_table
* symtab
)
3142 Incremental_inputs
* incr
= this->incremental_inputs_
;
3144 gold_assert(incr
!= NULL
);
3146 // Create the .gnu_incremental_inputs, _symtab, and _relocs input sections.
3147 incr
->create_data_sections(symtab
);
3149 // Add the .gnu_incremental_inputs section.
3150 const char* incremental_inputs_name
=
3151 this->namepool_
.add(".gnu_incremental_inputs", false, NULL
);
3152 Output_section
* incremental_inputs_os
=
3153 this->make_output_section(incremental_inputs_name
,
3154 elfcpp::SHT_GNU_INCREMENTAL_INPUTS
, 0,
3155 ORDER_INVALID
, false);
3156 incremental_inputs_os
->add_output_section_data(incr
->inputs_section());
3158 // Add the .gnu_incremental_symtab section.
3159 const char* incremental_symtab_name
=
3160 this->namepool_
.add(".gnu_incremental_symtab", false, NULL
);
3161 Output_section
* incremental_symtab_os
=
3162 this->make_output_section(incremental_symtab_name
,
3163 elfcpp::SHT_GNU_INCREMENTAL_SYMTAB
, 0,
3164 ORDER_INVALID
, false);
3165 incremental_symtab_os
->add_output_section_data(incr
->symtab_section());
3166 incremental_symtab_os
->set_entsize(4);
3168 // Add the .gnu_incremental_relocs section.
3169 const char* incremental_relocs_name
=
3170 this->namepool_
.add(".gnu_incremental_relocs", false, NULL
);
3171 Output_section
* incremental_relocs_os
=
3172 this->make_output_section(incremental_relocs_name
,
3173 elfcpp::SHT_GNU_INCREMENTAL_RELOCS
, 0,
3174 ORDER_INVALID
, false);
3175 incremental_relocs_os
->add_output_section_data(incr
->relocs_section());
3176 incremental_relocs_os
->set_entsize(incr
->relocs_entsize());
3178 // Add the .gnu_incremental_got_plt section.
3179 const char* incremental_got_plt_name
=
3180 this->namepool_
.add(".gnu_incremental_got_plt", false, NULL
);
3181 Output_section
* incremental_got_plt_os
=
3182 this->make_output_section(incremental_got_plt_name
,
3183 elfcpp::SHT_GNU_INCREMENTAL_GOT_PLT
, 0,
3184 ORDER_INVALID
, false);
3185 incremental_got_plt_os
->add_output_section_data(incr
->got_plt_section());
3187 // Add the .gnu_incremental_strtab section.
3188 const char* incremental_strtab_name
=
3189 this->namepool_
.add(".gnu_incremental_strtab", false, NULL
);
3190 Output_section
* incremental_strtab_os
= this->make_output_section(incremental_strtab_name
,
3191 elfcpp::SHT_STRTAB
, 0,
3192 ORDER_INVALID
, false);
3193 Output_data_strtab
* strtab_data
=
3194 new Output_data_strtab(incr
->get_stringpool());
3195 incremental_strtab_os
->add_output_section_data(strtab_data
);
3197 incremental_inputs_os
->set_after_input_sections();
3198 incremental_symtab_os
->set_after_input_sections();
3199 incremental_relocs_os
->set_after_input_sections();
3200 incremental_got_plt_os
->set_after_input_sections();
3202 incremental_inputs_os
->set_link_section(incremental_strtab_os
);
3203 incremental_symtab_os
->set_link_section(incremental_inputs_os
);
3204 incremental_relocs_os
->set_link_section(incremental_inputs_os
);
3205 incremental_got_plt_os
->set_link_section(incremental_inputs_os
);
3208 // Return whether SEG1 should be before SEG2 in the output file. This
3209 // is based entirely on the segment type and flags. When this is
3210 // called the segment addresses have normally not yet been set.
3213 Layout::segment_precedes(const Output_segment
* seg1
,
3214 const Output_segment
* seg2
)
3216 elfcpp::Elf_Word type1
= seg1
->type();
3217 elfcpp::Elf_Word type2
= seg2
->type();
3219 // The single PT_PHDR segment is required to precede any loadable
3220 // segment. We simply make it always first.
3221 if (type1
== elfcpp::PT_PHDR
)
3223 gold_assert(type2
!= elfcpp::PT_PHDR
);
3226 if (type2
== elfcpp::PT_PHDR
)
3229 // The single PT_INTERP segment is required to precede any loadable
3230 // segment. We simply make it always second.
3231 if (type1
== elfcpp::PT_INTERP
)
3233 gold_assert(type2
!= elfcpp::PT_INTERP
);
3236 if (type2
== elfcpp::PT_INTERP
)
3239 // We then put PT_LOAD segments before any other segments.
3240 if (type1
== elfcpp::PT_LOAD
&& type2
!= elfcpp::PT_LOAD
)
3242 if (type2
== elfcpp::PT_LOAD
&& type1
!= elfcpp::PT_LOAD
)
3245 // We put the PT_TLS segment last except for the PT_GNU_RELRO
3246 // segment, because that is where the dynamic linker expects to find
3247 // it (this is just for efficiency; other positions would also work
3249 if (type1
== elfcpp::PT_TLS
3250 && type2
!= elfcpp::PT_TLS
3251 && type2
!= elfcpp::PT_GNU_RELRO
)
3253 if (type2
== elfcpp::PT_TLS
3254 && type1
!= elfcpp::PT_TLS
3255 && type1
!= elfcpp::PT_GNU_RELRO
)
3258 // We put the PT_GNU_RELRO segment last, because that is where the
3259 // dynamic linker expects to find it (as with PT_TLS, this is just
3261 if (type1
== elfcpp::PT_GNU_RELRO
&& type2
!= elfcpp::PT_GNU_RELRO
)
3263 if (type2
== elfcpp::PT_GNU_RELRO
&& type1
!= elfcpp::PT_GNU_RELRO
)
3266 const elfcpp::Elf_Word flags1
= seg1
->flags();
3267 const elfcpp::Elf_Word flags2
= seg2
->flags();
3269 // The order of non-PT_LOAD segments is unimportant. We simply sort
3270 // by the numeric segment type and flags values. There should not
3271 // be more than one segment with the same type and flags, except
3272 // when a linker script specifies such.
3273 if (type1
!= elfcpp::PT_LOAD
)
3276 return type1
< type2
;
3277 gold_assert(flags1
!= flags2
3278 || this->script_options_
->saw_phdrs_clause());
3279 return flags1
< flags2
;
3282 // If the addresses are set already, sort by load address.
3283 if (seg1
->are_addresses_set())
3285 if (!seg2
->are_addresses_set())
3288 unsigned int section_count1
= seg1
->output_section_count();
3289 unsigned int section_count2
= seg2
->output_section_count();
3290 if (section_count1
== 0 && section_count2
> 0)
3292 if (section_count1
> 0 && section_count2
== 0)
3295 uint64_t paddr1
= (seg1
->are_addresses_set()
3297 : seg1
->first_section_load_address());
3298 uint64_t paddr2
= (seg2
->are_addresses_set()
3300 : seg2
->first_section_load_address());
3302 if (paddr1
!= paddr2
)
3303 return paddr1
< paddr2
;
3305 else if (seg2
->are_addresses_set())
3308 // A segment which holds large data comes after a segment which does
3309 // not hold large data.
3310 if (seg1
->is_large_data_segment())
3312 if (!seg2
->is_large_data_segment())
3315 else if (seg2
->is_large_data_segment())
3318 // Otherwise, we sort PT_LOAD segments based on the flags. Readonly
3319 // segments come before writable segments. Then writable segments
3320 // with data come before writable segments without data. Then
3321 // executable segments come before non-executable segments. Then
3322 // the unlikely case of a non-readable segment comes before the
3323 // normal case of a readable segment. If there are multiple
3324 // segments with the same type and flags, we require that the
3325 // address be set, and we sort by virtual address and then physical
3327 if ((flags1
& elfcpp::PF_W
) != (flags2
& elfcpp::PF_W
))
3328 return (flags1
& elfcpp::PF_W
) == 0;
3329 if ((flags1
& elfcpp::PF_W
) != 0
3330 && seg1
->has_any_data_sections() != seg2
->has_any_data_sections())
3331 return seg1
->has_any_data_sections();
3332 if ((flags1
& elfcpp::PF_X
) != (flags2
& elfcpp::PF_X
))
3333 return (flags1
& elfcpp::PF_X
) != 0;
3334 if ((flags1
& elfcpp::PF_R
) != (flags2
& elfcpp::PF_R
))
3335 return (flags1
& elfcpp::PF_R
) == 0;
3337 // We shouldn't get here--we shouldn't create segments which we
3338 // can't distinguish. Unless of course we are using a weird linker
3339 // script or overlapping --section-start options. We could also get
3340 // here if plugins want unique segments for subsets of sections.
3341 gold_assert(this->script_options_
->saw_phdrs_clause()
3342 || parameters
->options().any_section_start()
3343 || this->is_unique_segment_for_sections_specified());
3347 // Increase OFF so that it is congruent to ADDR modulo ABI_PAGESIZE.
3350 align_file_offset(off_t off
, uint64_t addr
, uint64_t abi_pagesize
)
3352 uint64_t unsigned_off
= off
;
3353 uint64_t aligned_off
= ((unsigned_off
& ~(abi_pagesize
- 1))
3354 | (addr
& (abi_pagesize
- 1)));
3355 if (aligned_off
< unsigned_off
)
3356 aligned_off
+= abi_pagesize
;
3360 // On targets where the text segment contains only executable code,
3361 // a non-executable segment is never the text segment.
3364 is_text_segment(const Target
* target
, const Output_segment
* seg
)
3366 elfcpp::Elf_Xword flags
= seg
->flags();
3367 if ((flags
& elfcpp::PF_W
) != 0)
3369 if ((flags
& elfcpp::PF_X
) == 0)
3370 return !target
->isolate_execinstr();
3374 // Set the file offsets of all the segments, and all the sections they
3375 // contain. They have all been created. LOAD_SEG must be be laid out
3376 // first. Return the offset of the data to follow.
3379 Layout::set_segment_offsets(const Target
* target
, Output_segment
* load_seg
,
3380 unsigned int* pshndx
)
3382 // Sort them into the final order. We use a stable sort so that we
3383 // don't randomize the order of indistinguishable segments created
3384 // by linker scripts.
3385 std::stable_sort(this->segment_list_
.begin(), this->segment_list_
.end(),
3386 Layout::Compare_segments(this));
3388 // Find the PT_LOAD segments, and set their addresses and offsets
3389 // and their section's addresses and offsets.
3390 uint64_t start_addr
;
3391 if (parameters
->options().user_set_Ttext())
3392 start_addr
= parameters
->options().Ttext();
3393 else if (parameters
->options().output_is_position_independent())
3396 start_addr
= target
->default_text_segment_address();
3398 uint64_t addr
= start_addr
;
3401 // If LOAD_SEG is NULL, then the file header and segment headers
3402 // will not be loadable. But they still need to be at offset 0 in
3403 // the file. Set their offsets now.
3404 if (load_seg
== NULL
)
3406 for (Data_list::iterator p
= this->special_output_list_
.begin();
3407 p
!= this->special_output_list_
.end();
3410 off
= align_address(off
, (*p
)->addralign());
3411 (*p
)->set_address_and_file_offset(0, off
);
3412 off
+= (*p
)->data_size();
3416 unsigned int increase_relro
= this->increase_relro_
;
3417 if (this->script_options_
->saw_sections_clause())
3420 const bool check_sections
= parameters
->options().check_sections();
3421 Output_segment
* last_load_segment
= NULL
;
3423 unsigned int shndx_begin
= *pshndx
;
3424 unsigned int shndx_load_seg
= *pshndx
;
3426 for (Segment_list::iterator p
= this->segment_list_
.begin();
3427 p
!= this->segment_list_
.end();
3430 if ((*p
)->type() == elfcpp::PT_LOAD
)
3432 if (target
->isolate_execinstr())
3434 // When we hit the segment that should contain the
3435 // file headers, reset the file offset so we place
3436 // it and subsequent segments appropriately.
3437 // We'll fix up the preceding segments below.
3445 shndx_load_seg
= *pshndx
;
3451 // Verify that the file headers fall into the first segment.
3452 if (load_seg
!= NULL
&& load_seg
!= *p
)
3457 bool are_addresses_set
= (*p
)->are_addresses_set();
3458 if (are_addresses_set
)
3460 // When it comes to setting file offsets, we care about
3461 // the physical address.
3462 addr
= (*p
)->paddr();
3464 else if (parameters
->options().user_set_Ttext()
3465 && (parameters
->options().omagic()
3466 || is_text_segment(target
, *p
)))
3468 are_addresses_set
= true;
3470 else if (parameters
->options().user_set_Trodata_segment()
3471 && ((*p
)->flags() & (elfcpp::PF_W
| elfcpp::PF_X
)) == 0)
3473 addr
= parameters
->options().Trodata_segment();
3474 are_addresses_set
= true;
3476 else if (parameters
->options().user_set_Tdata()
3477 && ((*p
)->flags() & elfcpp::PF_W
) != 0
3478 && (!parameters
->options().user_set_Tbss()
3479 || (*p
)->has_any_data_sections()))
3481 addr
= parameters
->options().Tdata();
3482 are_addresses_set
= true;
3484 else if (parameters
->options().user_set_Tbss()
3485 && ((*p
)->flags() & elfcpp::PF_W
) != 0
3486 && !(*p
)->has_any_data_sections())
3488 addr
= parameters
->options().Tbss();
3489 are_addresses_set
= true;
3492 uint64_t orig_addr
= addr
;
3493 uint64_t orig_off
= off
;
3495 uint64_t aligned_addr
= 0;
3496 uint64_t abi_pagesize
= target
->abi_pagesize();
3497 uint64_t common_pagesize
= target
->common_pagesize();
3499 if (!parameters
->options().nmagic()
3500 && !parameters
->options().omagic())
3501 (*p
)->set_minimum_p_align(abi_pagesize
);
3503 if (!are_addresses_set
)
3505 // Skip the address forward one page, maintaining the same
3506 // position within the page. This lets us store both segments
3507 // overlapping on a single page in the file, but the loader will
3508 // put them on different pages in memory. We will revisit this
3509 // decision once we know the size of the segment.
3511 addr
= align_address(addr
, (*p
)->maximum_alignment());
3512 aligned_addr
= addr
;
3516 // This is the segment that will contain the file
3517 // headers, so its offset will have to be exactly zero.
3518 gold_assert(orig_off
== 0);
3520 // If the target wants a fixed minimum distance from the
3521 // text segment to the read-only segment, move up now.
3523 start_addr
+ (parameters
->options().user_set_rosegment_gap()
3524 ? parameters
->options().rosegment_gap()
3525 : target
->rosegment_gap());
3526 if (addr
< min_addr
)
3529 // But this is not the first segment! To make its
3530 // address congruent with its offset, that address better
3531 // be aligned to the ABI-mandated page size.
3532 addr
= align_address(addr
, abi_pagesize
);
3533 aligned_addr
= addr
;
3537 if ((addr
& (abi_pagesize
- 1)) != 0)
3538 addr
= addr
+ abi_pagesize
;
3540 off
= orig_off
+ ((addr
- orig_addr
) & (abi_pagesize
- 1));
3544 if (!parameters
->options().nmagic()
3545 && !parameters
->options().omagic())
3547 // Here we are also taking care of the case when
3548 // the maximum segment alignment is larger than the page size.
3549 off
= align_file_offset(off
, addr
,
3550 std::max(abi_pagesize
,
3551 (*p
)->maximum_alignment()));
3555 // This is -N or -n with a section script which prevents
3556 // us from using a load segment. We need to ensure that
3557 // the file offset is aligned to the alignment of the
3558 // segment. This is because the linker script
3559 // implicitly assumed a zero offset. If we don't align
3560 // here, then the alignment of the sections in the
3561 // linker script may not match the alignment of the
3562 // sections in the set_section_addresses call below,
3563 // causing an error about dot moving backward.
3564 off
= align_address(off
, (*p
)->maximum_alignment());
3567 unsigned int shndx_hold
= *pshndx
;
3568 bool has_relro
= false;
3569 uint64_t new_addr
= (*p
)->set_section_addresses(target
, this,
3575 // Now that we know the size of this segment, we may be able
3576 // to save a page in memory, at the cost of wasting some
3577 // file space, by instead aligning to the start of a new
3578 // page. Here we use the real machine page size rather than
3579 // the ABI mandated page size. If the segment has been
3580 // aligned so that the relro data ends at a page boundary,
3581 // we do not try to realign it.
3583 if (!are_addresses_set
3585 && aligned_addr
!= addr
3586 && !parameters
->incremental())
3588 uint64_t first_off
= (common_pagesize
3590 & (common_pagesize
- 1)));
3591 uint64_t last_off
= new_addr
& (common_pagesize
- 1);
3594 && ((aligned_addr
& ~ (common_pagesize
- 1))
3595 != (new_addr
& ~ (common_pagesize
- 1)))
3596 && first_off
+ last_off
<= common_pagesize
)
3598 *pshndx
= shndx_hold
;
3599 addr
= align_address(aligned_addr
, common_pagesize
);
3600 addr
= align_address(addr
, (*p
)->maximum_alignment());
3601 if ((addr
& (abi_pagesize
- 1)) != 0)
3602 addr
= addr
+ abi_pagesize
;
3603 off
= orig_off
+ ((addr
- orig_addr
) & (abi_pagesize
- 1));
3604 off
= align_file_offset(off
, addr
, abi_pagesize
);
3606 increase_relro
= this->increase_relro_
;
3607 if (this->script_options_
->saw_sections_clause())
3611 new_addr
= (*p
)->set_section_addresses(target
, this,
3621 // Implement --check-sections. We know that the segments
3622 // are sorted by LMA.
3623 if (check_sections
&& last_load_segment
!= NULL
)
3625 gold_assert(last_load_segment
->paddr() <= (*p
)->paddr());
3626 if (last_load_segment
->paddr() + last_load_segment
->memsz()
3629 unsigned long long lb1
= last_load_segment
->paddr();
3630 unsigned long long le1
= lb1
+ last_load_segment
->memsz();
3631 unsigned long long lb2
= (*p
)->paddr();
3632 unsigned long long le2
= lb2
+ (*p
)->memsz();
3633 gold_error(_("load segment overlap [0x%llx -> 0x%llx] and "
3634 "[0x%llx -> 0x%llx]"),
3635 lb1
, le1
, lb2
, le2
);
3638 last_load_segment
= *p
;
3642 if (load_seg
!= NULL
&& target
->isolate_execinstr())
3644 // Process the early segments again, setting their file offsets
3645 // so they land after the segments starting at LOAD_SEG.
3646 off
= align_file_offset(off
, 0, target
->abi_pagesize());
3648 this->reset_relax_output();
3650 for (Segment_list::iterator p
= this->segment_list_
.begin();
3654 if ((*p
)->type() == elfcpp::PT_LOAD
)
3656 // We repeat the whole job of assigning addresses and
3657 // offsets, but we really only want to change the offsets and
3658 // must ensure that the addresses all come out the same as
3659 // they did the first time through.
3660 bool has_relro
= false;
3661 const uint64_t old_addr
= (*p
)->vaddr();
3662 const uint64_t old_end
= old_addr
+ (*p
)->memsz();
3663 uint64_t new_addr
= (*p
)->set_section_addresses(target
, this,
3669 gold_assert(new_addr
== old_end
);
3673 gold_assert(shndx_begin
== shndx_load_seg
);
3676 // Handle the non-PT_LOAD segments, setting their offsets from their
3677 // section's offsets.
3678 for (Segment_list::iterator p
= this->segment_list_
.begin();
3679 p
!= this->segment_list_
.end();
3682 if ((*p
)->type() != elfcpp::PT_LOAD
)
3683 (*p
)->set_offset((*p
)->type() == elfcpp::PT_GNU_RELRO
3688 // Set the TLS offsets for each section in the PT_TLS segment.
3689 if (this->tls_segment_
!= NULL
)
3690 this->tls_segment_
->set_tls_offsets();
3695 // Set the offsets of all the allocated sections when doing a
3696 // relocatable link. This does the same jobs as set_segment_offsets,
3697 // only for a relocatable link.
3700 Layout::set_relocatable_section_offsets(Output_data
* file_header
,
3701 unsigned int* pshndx
)
3705 file_header
->set_address_and_file_offset(0, 0);
3706 off
+= file_header
->data_size();
3708 for (Section_list::iterator p
= this->section_list_
.begin();
3709 p
!= this->section_list_
.end();
3712 // We skip unallocated sections here, except that group sections
3713 // have to come first.
3714 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) == 0
3715 && (*p
)->type() != elfcpp::SHT_GROUP
)
3718 off
= align_address(off
, (*p
)->addralign());
3720 // The linker script might have set the address.
3721 if (!(*p
)->is_address_valid())
3722 (*p
)->set_address(0);
3723 (*p
)->set_file_offset(off
);
3724 (*p
)->finalize_data_size();
3725 if ((*p
)->type() != elfcpp::SHT_NOBITS
)
3726 off
+= (*p
)->data_size();
3728 (*p
)->set_out_shndx(*pshndx
);
3735 // Set the file offset of all the sections not associated with a
3739 Layout::set_section_offsets(off_t off
, Layout::Section_offset_pass pass
)
3741 off_t startoff
= off
;
3744 for (Section_list::iterator p
= this->unattached_section_list_
.begin();
3745 p
!= this->unattached_section_list_
.end();
3748 // The symtab section is handled in create_symtab_sections.
3749 if (*p
== this->symtab_section_
)
3752 // If we've already set the data size, don't set it again.
3753 if ((*p
)->is_offset_valid() && (*p
)->is_data_size_valid())
3756 if (pass
== BEFORE_INPUT_SECTIONS_PASS
3757 && (*p
)->requires_postprocessing())
3759 (*p
)->create_postprocessing_buffer();
3760 this->any_postprocessing_sections_
= true;
3763 if (pass
== BEFORE_INPUT_SECTIONS_PASS
3764 && (*p
)->after_input_sections())
3766 else if (pass
== POSTPROCESSING_SECTIONS_PASS
3767 && (!(*p
)->after_input_sections()
3768 || (*p
)->type() == elfcpp::SHT_STRTAB
))
3770 else if (pass
== STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
3771 && (!(*p
)->after_input_sections()
3772 || (*p
)->type() != elfcpp::SHT_STRTAB
))
3775 if (!parameters
->incremental_update())
3777 off
= align_address(off
, (*p
)->addralign());
3778 (*p
)->set_file_offset(off
);
3779 (*p
)->finalize_data_size();
3783 // Incremental update: allocate file space from free list.
3784 (*p
)->pre_finalize_data_size();
3785 off_t current_size
= (*p
)->current_data_size();
3786 off
= this->allocate(current_size
, (*p
)->addralign(), startoff
);
3789 if (is_debugging_enabled(DEBUG_INCREMENTAL
))
3790 this->free_list_
.dump();
3791 gold_assert((*p
)->output_section() != NULL
);
3792 gold_fallback(_("out of patch space for section %s; "
3793 "relink with --incremental-full"),
3794 (*p
)->output_section()->name());
3796 (*p
)->set_file_offset(off
);
3797 (*p
)->finalize_data_size();
3798 if ((*p
)->data_size() > current_size
)
3800 gold_assert((*p
)->output_section() != NULL
);
3801 gold_fallback(_("%s: section changed size; "
3802 "relink with --incremental-full"),
3803 (*p
)->output_section()->name());
3805 gold_debug(DEBUG_INCREMENTAL
,
3806 "set_section_offsets: %08lx %08lx %s",
3807 static_cast<long>(off
),
3808 static_cast<long>((*p
)->data_size()),
3809 ((*p
)->output_section() != NULL
3810 ? (*p
)->output_section()->name() : "(special)"));
3813 off
+= (*p
)->data_size();
3817 // At this point the name must be set.
3818 if (pass
!= STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
)
3819 this->namepool_
.add((*p
)->name(), false, NULL
);
3824 // Set the section indexes of all the sections not associated with a
3828 Layout::set_section_indexes(unsigned int shndx
)
3830 for (Section_list::iterator p
= this->unattached_section_list_
.begin();
3831 p
!= this->unattached_section_list_
.end();
3834 if (!(*p
)->has_out_shndx())
3836 (*p
)->set_out_shndx(shndx
);
3843 // Set the section addresses according to the linker script. This is
3844 // only called when we see a SECTIONS clause. This returns the
3845 // program segment which should hold the file header and segment
3846 // headers, if any. It will return NULL if they should not be in a
3850 Layout::set_section_addresses_from_script(Symbol_table
* symtab
)
3852 Script_sections
* ss
= this->script_options_
->script_sections();
3853 gold_assert(ss
->saw_sections_clause());
3854 return this->script_options_
->set_section_addresses(symtab
, this);
3857 // Place the orphan sections in the linker script.
3860 Layout::place_orphan_sections_in_script()
3862 Script_sections
* ss
= this->script_options_
->script_sections();
3863 gold_assert(ss
->saw_sections_clause());
3865 // Place each orphaned output section in the script.
3866 for (Section_list::iterator p
= this->section_list_
.begin();
3867 p
!= this->section_list_
.end();
3870 if (!(*p
)->found_in_sections_clause())
3871 ss
->place_orphan(*p
);
3875 // Count the local symbols in the regular symbol table and the dynamic
3876 // symbol table, and build the respective string pools.
3879 Layout::count_local_symbols(const Task
* task
,
3880 const Input_objects
* input_objects
)
3882 // First, figure out an upper bound on the number of symbols we'll
3883 // be inserting into each pool. This helps us create the pools with
3884 // the right size, to avoid unnecessary hashtable resizing.
3885 unsigned int symbol_count
= 0;
3886 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
3887 p
!= input_objects
->relobj_end();
3889 symbol_count
+= (*p
)->local_symbol_count();
3891 // Go from "upper bound" to "estimate." We overcount for two
3892 // reasons: we double-count symbols that occur in more than one
3893 // object file, and we count symbols that are dropped from the
3894 // output. Add it all together and assume we overcount by 100%.
3897 // We assume all symbols will go into both the sympool and dynpool.
3898 this->sympool_
.reserve(symbol_count
);
3899 this->dynpool_
.reserve(symbol_count
);
3901 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
3902 p
!= input_objects
->relobj_end();
3905 Task_lock_obj
<Object
> tlo(task
, *p
);
3906 (*p
)->count_local_symbols(&this->sympool_
, &this->dynpool_
);
3910 // Create the symbol table sections. Here we also set the final
3911 // values of the symbols. At this point all the loadable sections are
3912 // fully laid out. SHNUM is the number of sections so far.
3915 Layout::create_symtab_sections(const Input_objects
* input_objects
,
3916 Symbol_table
* symtab
,
3922 if (parameters
->target().get_size() == 32)
3924 symsize
= elfcpp::Elf_sizes
<32>::sym_size
;
3927 else if (parameters
->target().get_size() == 64)
3929 symsize
= elfcpp::Elf_sizes
<64>::sym_size
;
3935 // Compute file offsets relative to the start of the symtab section.
3938 // Save space for the dummy symbol at the start of the section. We
3939 // never bother to write this out--it will just be left as zero.
3941 unsigned int local_symbol_index
= 1;
3943 // Add STT_SECTION symbols for each Output section which needs one.
3944 for (Section_list::iterator p
= this->section_list_
.begin();
3945 p
!= this->section_list_
.end();
3948 if (!(*p
)->needs_symtab_index())
3949 (*p
)->set_symtab_index(-1U);
3952 (*p
)->set_symtab_index(local_symbol_index
);
3953 ++local_symbol_index
;
3958 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
3959 p
!= input_objects
->relobj_end();
3962 unsigned int index
= (*p
)->finalize_local_symbols(local_symbol_index
,
3964 off
+= (index
- local_symbol_index
) * symsize
;
3965 local_symbol_index
= index
;
3968 unsigned int local_symcount
= local_symbol_index
;
3969 gold_assert(static_cast<off_t
>(local_symcount
* symsize
) == off
);
3972 size_t dyn_global_index
;
3974 if (this->dynsym_section_
== NULL
)
3977 dyn_global_index
= 0;
3982 dyn_global_index
= this->dynsym_section_
->info();
3983 off_t locsize
= dyn_global_index
* this->dynsym_section_
->entsize();
3984 dynoff
= this->dynsym_section_
->offset() + locsize
;
3985 dyncount
= (this->dynsym_section_
->data_size() - locsize
) / symsize
;
3986 gold_assert(static_cast<off_t
>(dyncount
* symsize
)
3987 == this->dynsym_section_
->data_size() - locsize
);
3990 off_t global_off
= off
;
3991 off
= symtab
->finalize(off
, dynoff
, dyn_global_index
, dyncount
,
3992 &this->sympool_
, &local_symcount
);
3994 if (!parameters
->options().strip_all())
3996 this->sympool_
.set_string_offsets();
3998 const char* symtab_name
= this->namepool_
.add(".symtab", false, NULL
);
3999 Output_section
* osymtab
= this->make_output_section(symtab_name
,
4003 this->symtab_section_
= osymtab
;
4005 Output_section_data
* pos
= new Output_data_fixed_space(off
, align
,
4007 osymtab
->add_output_section_data(pos
);
4009 // We generate a .symtab_shndx section if we have more than
4010 // SHN_LORESERVE sections. Technically it is possible that we
4011 // don't need one, because it is possible that there are no
4012 // symbols in any of sections with indexes larger than
4013 // SHN_LORESERVE. That is probably unusual, though, and it is
4014 // easier to always create one than to compute section indexes
4015 // twice (once here, once when writing out the symbols).
4016 if (shnum
>= elfcpp::SHN_LORESERVE
)
4018 const char* symtab_xindex_name
= this->namepool_
.add(".symtab_shndx",
4020 Output_section
* osymtab_xindex
=
4021 this->make_output_section(symtab_xindex_name
,
4022 elfcpp::SHT_SYMTAB_SHNDX
, 0,
4023 ORDER_INVALID
, false);
4025 size_t symcount
= off
/ symsize
;
4026 this->symtab_xindex_
= new Output_symtab_xindex(symcount
);
4028 osymtab_xindex
->add_output_section_data(this->symtab_xindex_
);
4030 osymtab_xindex
->set_link_section(osymtab
);
4031 osymtab_xindex
->set_addralign(4);
4032 osymtab_xindex
->set_entsize(4);
4034 osymtab_xindex
->set_after_input_sections();
4036 // This tells the driver code to wait until the symbol table
4037 // has written out before writing out the postprocessing
4038 // sections, including the .symtab_shndx section.
4039 this->any_postprocessing_sections_
= true;
4042 const char* strtab_name
= this->namepool_
.add(".strtab", false, NULL
);
4043 Output_section
* ostrtab
= this->make_output_section(strtab_name
,
4048 Output_section_data
* pstr
= new Output_data_strtab(&this->sympool_
);
4049 ostrtab
->add_output_section_data(pstr
);
4052 if (!parameters
->incremental_update())
4053 symtab_off
= align_address(*poff
, align
);
4056 symtab_off
= this->allocate(off
, align
, *poff
);
4058 gold_fallback(_("out of patch space for symbol table; "
4059 "relink with --incremental-full"));
4060 gold_debug(DEBUG_INCREMENTAL
,
4061 "create_symtab_sections: %08lx %08lx .symtab",
4062 static_cast<long>(symtab_off
),
4063 static_cast<long>(off
));
4066 symtab
->set_file_offset(symtab_off
+ global_off
);
4067 osymtab
->set_file_offset(symtab_off
);
4068 osymtab
->finalize_data_size();
4069 osymtab
->set_link_section(ostrtab
);
4070 osymtab
->set_info(local_symcount
);
4071 osymtab
->set_entsize(symsize
);
4073 if (symtab_off
+ off
> *poff
)
4074 *poff
= symtab_off
+ off
;
4078 // Create the .shstrtab section, which holds the names of the
4079 // sections. At the time this is called, we have created all the
4080 // output sections except .shstrtab itself.
4083 Layout::create_shstrtab()
4085 // FIXME: We don't need to create a .shstrtab section if we are
4086 // stripping everything.
4088 const char* name
= this->namepool_
.add(".shstrtab", false, NULL
);
4090 Output_section
* os
= this->make_output_section(name
, elfcpp::SHT_STRTAB
, 0,
4091 ORDER_INVALID
, false);
4093 if (strcmp(parameters
->options().compress_debug_sections(), "none") != 0)
4095 // We can't write out this section until we've set all the
4096 // section names, and we don't set the names of compressed
4097 // output sections until relocations are complete. FIXME: With
4098 // the current names we use, this is unnecessary.
4099 os
->set_after_input_sections();
4102 Output_section_data
* posd
= new Output_data_strtab(&this->namepool_
);
4103 os
->add_output_section_data(posd
);
4108 // Create the section headers. SIZE is 32 or 64. OFF is the file
4112 Layout::create_shdrs(const Output_section
* shstrtab_section
, off_t
* poff
)
4114 Output_section_headers
* oshdrs
;
4115 oshdrs
= new Output_section_headers(this,
4116 &this->segment_list_
,
4117 &this->section_list_
,
4118 &this->unattached_section_list_
,
4122 if (!parameters
->incremental_update())
4123 off
= align_address(*poff
, oshdrs
->addralign());
4126 oshdrs
->pre_finalize_data_size();
4127 off
= this->allocate(oshdrs
->data_size(), oshdrs
->addralign(), *poff
);
4129 gold_fallback(_("out of patch space for section header table; "
4130 "relink with --incremental-full"));
4131 gold_debug(DEBUG_INCREMENTAL
,
4132 "create_shdrs: %08lx %08lx (section header table)",
4133 static_cast<long>(off
),
4134 static_cast<long>(off
+ oshdrs
->data_size()));
4136 oshdrs
->set_address_and_file_offset(0, off
);
4137 off
+= oshdrs
->data_size();
4140 this->section_headers_
= oshdrs
;
4143 // Count the allocated sections.
4146 Layout::allocated_output_section_count() const
4148 size_t section_count
= 0;
4149 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
4150 p
!= this->segment_list_
.end();
4152 section_count
+= (*p
)->output_section_count();
4153 return section_count
;
4156 // Create the dynamic symbol table.
4159 Layout::create_dynamic_symtab(const Input_objects
* input_objects
,
4160 Symbol_table
* symtab
,
4161 Output_section
** pdynstr
,
4162 unsigned int* plocal_dynamic_count
,
4163 std::vector
<Symbol
*>* pdynamic_symbols
,
4164 Versions
* pversions
)
4166 // Count all the symbols in the dynamic symbol table, and set the
4167 // dynamic symbol indexes.
4169 // Skip symbol 0, which is always all zeroes.
4170 unsigned int index
= 1;
4172 // Add STT_SECTION symbols for each Output section which needs one.
4173 for (Section_list::iterator p
= this->section_list_
.begin();
4174 p
!= this->section_list_
.end();
4177 if (!(*p
)->needs_dynsym_index())
4178 (*p
)->set_dynsym_index(-1U);
4181 (*p
)->set_dynsym_index(index
);
4186 // Count the local symbols that need to go in the dynamic symbol table,
4187 // and set the dynamic symbol indexes.
4188 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
4189 p
!= input_objects
->relobj_end();
4192 unsigned int new_index
= (*p
)->set_local_dynsym_indexes(index
);
4196 unsigned int local_symcount
= index
;
4197 *plocal_dynamic_count
= local_symcount
;
4199 index
= symtab
->set_dynsym_indexes(index
, pdynamic_symbols
,
4200 &this->dynpool_
, pversions
);
4204 const int size
= parameters
->target().get_size();
4207 symsize
= elfcpp::Elf_sizes
<32>::sym_size
;
4210 else if (size
== 64)
4212 symsize
= elfcpp::Elf_sizes
<64>::sym_size
;
4218 // Create the dynamic symbol table section.
4220 Output_section
* dynsym
= this->choose_output_section(NULL
, ".dynsym",
4224 ORDER_DYNAMIC_LINKER
,
4227 // Check for NULL as a linker script may discard .dynsym.
4230 Output_section_data
* odata
= new Output_data_fixed_space(index
* symsize
,
4233 dynsym
->add_output_section_data(odata
);
4235 dynsym
->set_info(local_symcount
);
4236 dynsym
->set_entsize(symsize
);
4237 dynsym
->set_addralign(align
);
4239 this->dynsym_section_
= dynsym
;
4242 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
4245 odyn
->add_section_address(elfcpp::DT_SYMTAB
, dynsym
);
4246 odyn
->add_constant(elfcpp::DT_SYMENT
, symsize
);
4249 // If there are more than SHN_LORESERVE allocated sections, we
4250 // create a .dynsym_shndx section. It is possible that we don't
4251 // need one, because it is possible that there are no dynamic
4252 // symbols in any of the sections with indexes larger than
4253 // SHN_LORESERVE. This is probably unusual, though, and at this
4254 // time we don't know the actual section indexes so it is
4255 // inconvenient to check.
4256 if (this->allocated_output_section_count() >= elfcpp::SHN_LORESERVE
)
4258 Output_section
* dynsym_xindex
=
4259 this->choose_output_section(NULL
, ".dynsym_shndx",
4260 elfcpp::SHT_SYMTAB_SHNDX
,
4262 false, ORDER_DYNAMIC_LINKER
, false);
4264 if (dynsym_xindex
!= NULL
)
4266 this->dynsym_xindex_
= new Output_symtab_xindex(index
);
4268 dynsym_xindex
->add_output_section_data(this->dynsym_xindex_
);
4270 dynsym_xindex
->set_link_section(dynsym
);
4271 dynsym_xindex
->set_addralign(4);
4272 dynsym_xindex
->set_entsize(4);
4274 dynsym_xindex
->set_after_input_sections();
4276 // This tells the driver code to wait until the symbol table
4277 // has written out before writing out the postprocessing
4278 // sections, including the .dynsym_shndx section.
4279 this->any_postprocessing_sections_
= true;
4283 // Create the dynamic string table section.
4285 Output_section
* dynstr
= this->choose_output_section(NULL
, ".dynstr",
4289 ORDER_DYNAMIC_LINKER
,
4294 Output_section_data
* strdata
= new Output_data_strtab(&this->dynpool_
);
4295 dynstr
->add_output_section_data(strdata
);
4298 dynsym
->set_link_section(dynstr
);
4299 if (this->dynamic_section_
!= NULL
)
4300 this->dynamic_section_
->set_link_section(dynstr
);
4304 odyn
->add_section_address(elfcpp::DT_STRTAB
, dynstr
);
4305 odyn
->add_section_size(elfcpp::DT_STRSZ
, dynstr
);
4309 // Create the hash tables.
4311 if (strcmp(parameters
->options().hash_style(), "sysv") == 0
4312 || strcmp(parameters
->options().hash_style(), "both") == 0)
4314 unsigned char* phash
;
4315 unsigned int hashlen
;
4316 Dynobj::create_elf_hash_table(*pdynamic_symbols
, local_symcount
,
4319 Output_section
* hashsec
=
4320 this->choose_output_section(NULL
, ".hash", elfcpp::SHT_HASH
,
4321 elfcpp::SHF_ALLOC
, false,
4322 ORDER_DYNAMIC_LINKER
, false);
4324 Output_section_data
* hashdata
= new Output_data_const_buffer(phash
,
4328 if (hashsec
!= NULL
&& hashdata
!= NULL
)
4329 hashsec
->add_output_section_data(hashdata
);
4331 if (hashsec
!= NULL
)
4334 hashsec
->set_link_section(dynsym
);
4335 hashsec
->set_entsize(4);
4339 odyn
->add_section_address(elfcpp::DT_HASH
, hashsec
);
4342 if (strcmp(parameters
->options().hash_style(), "gnu") == 0
4343 || strcmp(parameters
->options().hash_style(), "both") == 0)
4345 unsigned char* phash
;
4346 unsigned int hashlen
;
4347 Dynobj::create_gnu_hash_table(*pdynamic_symbols
, local_symcount
,
4350 Output_section
* hashsec
=
4351 this->choose_output_section(NULL
, ".gnu.hash", elfcpp::SHT_GNU_HASH
,
4352 elfcpp::SHF_ALLOC
, false,
4353 ORDER_DYNAMIC_LINKER
, false);
4355 Output_section_data
* hashdata
= new Output_data_const_buffer(phash
,
4359 if (hashsec
!= NULL
&& hashdata
!= NULL
)
4360 hashsec
->add_output_section_data(hashdata
);
4362 if (hashsec
!= NULL
)
4365 hashsec
->set_link_section(dynsym
);
4367 // For a 64-bit target, the entries in .gnu.hash do not have
4368 // a uniform size, so we only set the entry size for a
4370 if (parameters
->target().get_size() == 32)
4371 hashsec
->set_entsize(4);
4374 odyn
->add_section_address(elfcpp::DT_GNU_HASH
, hashsec
);
4379 // Assign offsets to each local portion of the dynamic symbol table.
4382 Layout::assign_local_dynsym_offsets(const Input_objects
* input_objects
)
4384 Output_section
* dynsym
= this->dynsym_section_
;
4388 off_t off
= dynsym
->offset();
4390 // Skip the dummy symbol at the start of the section.
4391 off
+= dynsym
->entsize();
4393 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
4394 p
!= input_objects
->relobj_end();
4397 unsigned int count
= (*p
)->set_local_dynsym_offset(off
);
4398 off
+= count
* dynsym
->entsize();
4402 // Create the version sections.
4405 Layout::create_version_sections(const Versions
* versions
,
4406 const Symbol_table
* symtab
,
4407 unsigned int local_symcount
,
4408 const std::vector
<Symbol
*>& dynamic_symbols
,
4409 const Output_section
* dynstr
)
4411 if (!versions
->any_defs() && !versions
->any_needs())
4414 switch (parameters
->size_and_endianness())
4416 #ifdef HAVE_TARGET_32_LITTLE
4417 case Parameters::TARGET_32_LITTLE
:
4418 this->sized_create_version_sections
<32, false>(versions
, symtab
,
4420 dynamic_symbols
, dynstr
);
4423 #ifdef HAVE_TARGET_32_BIG
4424 case Parameters::TARGET_32_BIG
:
4425 this->sized_create_version_sections
<32, true>(versions
, symtab
,
4427 dynamic_symbols
, dynstr
);
4430 #ifdef HAVE_TARGET_64_LITTLE
4431 case Parameters::TARGET_64_LITTLE
:
4432 this->sized_create_version_sections
<64, false>(versions
, symtab
,
4434 dynamic_symbols
, dynstr
);
4437 #ifdef HAVE_TARGET_64_BIG
4438 case Parameters::TARGET_64_BIG
:
4439 this->sized_create_version_sections
<64, true>(versions
, symtab
,
4441 dynamic_symbols
, dynstr
);
4449 // Create the version sections, sized version.
4451 template<int size
, bool big_endian
>
4453 Layout::sized_create_version_sections(
4454 const Versions
* versions
,
4455 const Symbol_table
* symtab
,
4456 unsigned int local_symcount
,
4457 const std::vector
<Symbol
*>& dynamic_symbols
,
4458 const Output_section
* dynstr
)
4460 Output_section
* vsec
= this->choose_output_section(NULL
, ".gnu.version",
4461 elfcpp::SHT_GNU_versym
,
4464 ORDER_DYNAMIC_LINKER
,
4467 // Check for NULL since a linker script may discard this section.
4470 unsigned char* vbuf
;
4472 versions
->symbol_section_contents
<size
, big_endian
>(symtab
,
4478 Output_section_data
* vdata
= new Output_data_const_buffer(vbuf
, vsize
, 2,
4481 vsec
->add_output_section_data(vdata
);
4482 vsec
->set_entsize(2);
4483 vsec
->set_link_section(this->dynsym_section_
);
4486 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
4487 if (odyn
!= NULL
&& vsec
!= NULL
)
4488 odyn
->add_section_address(elfcpp::DT_VERSYM
, vsec
);
4490 if (versions
->any_defs())
4492 Output_section
* vdsec
;
4493 vdsec
= this->choose_output_section(NULL
, ".gnu.version_d",
4494 elfcpp::SHT_GNU_verdef
,
4496 false, ORDER_DYNAMIC_LINKER
, false);
4500 unsigned char* vdbuf
;
4501 unsigned int vdsize
;
4502 unsigned int vdentries
;
4503 versions
->def_section_contents
<size
, big_endian
>(&this->dynpool_
,
4507 Output_section_data
* vddata
=
4508 new Output_data_const_buffer(vdbuf
, vdsize
, 4, "** version defs");
4510 vdsec
->add_output_section_data(vddata
);
4511 vdsec
->set_link_section(dynstr
);
4512 vdsec
->set_info(vdentries
);
4516 odyn
->add_section_address(elfcpp::DT_VERDEF
, vdsec
);
4517 odyn
->add_constant(elfcpp::DT_VERDEFNUM
, vdentries
);
4522 if (versions
->any_needs())
4524 Output_section
* vnsec
;
4525 vnsec
= this->choose_output_section(NULL
, ".gnu.version_r",
4526 elfcpp::SHT_GNU_verneed
,
4528 false, ORDER_DYNAMIC_LINKER
, false);
4532 unsigned char* vnbuf
;
4533 unsigned int vnsize
;
4534 unsigned int vnentries
;
4535 versions
->need_section_contents
<size
, big_endian
>(&this->dynpool_
,
4539 Output_section_data
* vndata
=
4540 new Output_data_const_buffer(vnbuf
, vnsize
, 4, "** version refs");
4542 vnsec
->add_output_section_data(vndata
);
4543 vnsec
->set_link_section(dynstr
);
4544 vnsec
->set_info(vnentries
);
4548 odyn
->add_section_address(elfcpp::DT_VERNEED
, vnsec
);
4549 odyn
->add_constant(elfcpp::DT_VERNEEDNUM
, vnentries
);
4555 // Create the .interp section and PT_INTERP segment.
4558 Layout::create_interp(const Target
* target
)
4560 gold_assert(this->interp_segment_
== NULL
);
4562 const char* interp
= parameters
->options().dynamic_linker();
4565 interp
= target
->dynamic_linker();
4566 gold_assert(interp
!= NULL
);
4569 size_t len
= strlen(interp
) + 1;
4571 Output_section_data
* odata
= new Output_data_const(interp
, len
, 1);
4573 Output_section
* osec
= this->choose_output_section(NULL
, ".interp",
4574 elfcpp::SHT_PROGBITS
,
4576 false, ORDER_INTERP
,
4579 osec
->add_output_section_data(odata
);
4582 // Add dynamic tags for the PLT and the dynamic relocs. This is
4583 // called by the target-specific code. This does nothing if not doing
4586 // USE_REL is true for REL relocs rather than RELA relocs.
4588 // If PLT_GOT is not NULL, then DT_PLTGOT points to it.
4590 // If PLT_REL is not NULL, it is used for DT_PLTRELSZ, and DT_JMPREL,
4591 // and we also set DT_PLTREL. We use PLT_REL's output section, since
4592 // some targets have multiple reloc sections in PLT_REL.
4594 // If DYN_REL is not NULL, it is used for DT_REL/DT_RELA,
4595 // DT_RELSZ/DT_RELASZ, DT_RELENT/DT_RELAENT. Again we use the output
4598 // If ADD_DEBUG is true, we add a DT_DEBUG entry when generating an
4602 Layout::add_target_dynamic_tags(bool use_rel
, const Output_data
* plt_got
,
4603 const Output_data
* plt_rel
,
4604 const Output_data_reloc_generic
* dyn_rel
,
4605 bool add_debug
, bool dynrel_includes_plt
)
4607 Output_data_dynamic
* odyn
= this->dynamic_data_
;
4611 if (plt_got
!= NULL
&& plt_got
->output_section() != NULL
)
4612 odyn
->add_section_address(elfcpp::DT_PLTGOT
, plt_got
);
4614 if (plt_rel
!= NULL
&& plt_rel
->output_section() != NULL
)
4616 odyn
->add_section_size(elfcpp::DT_PLTRELSZ
, plt_rel
->output_section());
4617 odyn
->add_section_address(elfcpp::DT_JMPREL
, plt_rel
->output_section());
4618 odyn
->add_constant(elfcpp::DT_PLTREL
,
4619 use_rel
? elfcpp::DT_REL
: elfcpp::DT_RELA
);
4622 if ((dyn_rel
!= NULL
&& dyn_rel
->output_section() != NULL
)
4623 || (dynrel_includes_plt
4625 && plt_rel
->output_section() != NULL
))
4627 bool have_dyn_rel
= dyn_rel
!= NULL
&& dyn_rel
->output_section() != NULL
;
4628 bool have_plt_rel
= plt_rel
!= NULL
&& plt_rel
->output_section() != NULL
;
4629 odyn
->add_section_address(use_rel
? elfcpp::DT_REL
: elfcpp::DT_RELA
,
4631 ? dyn_rel
->output_section()
4632 : plt_rel
->output_section()));
4633 elfcpp::DT size_tag
= use_rel
? elfcpp::DT_RELSZ
: elfcpp::DT_RELASZ
;
4634 if (have_dyn_rel
&& have_plt_rel
&& dynrel_includes_plt
)
4635 odyn
->add_section_size(size_tag
,
4636 dyn_rel
->output_section(),
4637 plt_rel
->output_section());
4638 else if (have_dyn_rel
)
4639 odyn
->add_section_size(size_tag
, dyn_rel
->output_section());
4641 odyn
->add_section_size(size_tag
, plt_rel
->output_section());
4642 const int size
= parameters
->target().get_size();
4647 rel_tag
= elfcpp::DT_RELENT
;
4649 rel_size
= Reloc_types
<elfcpp::SHT_REL
, 32, false>::reloc_size
;
4650 else if (size
== 64)
4651 rel_size
= Reloc_types
<elfcpp::SHT_REL
, 64, false>::reloc_size
;
4657 rel_tag
= elfcpp::DT_RELAENT
;
4659 rel_size
= Reloc_types
<elfcpp::SHT_RELA
, 32, false>::reloc_size
;
4660 else if (size
== 64)
4661 rel_size
= Reloc_types
<elfcpp::SHT_RELA
, 64, false>::reloc_size
;
4665 odyn
->add_constant(rel_tag
, rel_size
);
4667 if (parameters
->options().combreloc() && have_dyn_rel
)
4669 size_t c
= dyn_rel
->relative_reloc_count();
4671 odyn
->add_constant((use_rel
4672 ? elfcpp::DT_RELCOUNT
4673 : elfcpp::DT_RELACOUNT
),
4678 if (add_debug
&& !parameters
->options().shared())
4680 // The value of the DT_DEBUG tag is filled in by the dynamic
4681 // linker at run time, and used by the debugger.
4682 odyn
->add_constant(elfcpp::DT_DEBUG
, 0);
4686 // Finish the .dynamic section and PT_DYNAMIC segment.
4689 Layout::finish_dynamic_section(const Input_objects
* input_objects
,
4690 const Symbol_table
* symtab
)
4692 if (!this->script_options_
->saw_phdrs_clause()
4693 && this->dynamic_section_
!= NULL
)
4695 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_DYNAMIC
,
4698 oseg
->add_output_section_to_nonload(this->dynamic_section_
,
4699 elfcpp::PF_R
| elfcpp::PF_W
);
4702 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
4706 for (Input_objects::Dynobj_iterator p
= input_objects
->dynobj_begin();
4707 p
!= input_objects
->dynobj_end();
4710 if (!(*p
)->is_needed() && (*p
)->as_needed())
4712 // This dynamic object was linked with --as-needed, but it
4717 odyn
->add_string(elfcpp::DT_NEEDED
, (*p
)->soname());
4720 if (parameters
->options().shared())
4722 const char* soname
= parameters
->options().soname();
4724 odyn
->add_string(elfcpp::DT_SONAME
, soname
);
4727 Symbol
* sym
= symtab
->lookup(parameters
->options().init());
4728 if (sym
!= NULL
&& sym
->is_defined() && !sym
->is_from_dynobj())
4729 odyn
->add_symbol(elfcpp::DT_INIT
, sym
);
4731 sym
= symtab
->lookup(parameters
->options().fini());
4732 if (sym
!= NULL
&& sym
->is_defined() && !sym
->is_from_dynobj())
4733 odyn
->add_symbol(elfcpp::DT_FINI
, sym
);
4735 // Look for .init_array, .preinit_array and .fini_array by checking
4737 for(Layout::Section_list::const_iterator p
= this->section_list_
.begin();
4738 p
!= this->section_list_
.end();
4740 switch((*p
)->type())
4742 case elfcpp::SHT_FINI_ARRAY
:
4743 odyn
->add_section_address(elfcpp::DT_FINI_ARRAY
, *p
);
4744 odyn
->add_section_size(elfcpp::DT_FINI_ARRAYSZ
, *p
);
4746 case elfcpp::SHT_INIT_ARRAY
:
4747 odyn
->add_section_address(elfcpp::DT_INIT_ARRAY
, *p
);
4748 odyn
->add_section_size(elfcpp::DT_INIT_ARRAYSZ
, *p
);
4750 case elfcpp::SHT_PREINIT_ARRAY
:
4751 odyn
->add_section_address(elfcpp::DT_PREINIT_ARRAY
, *p
);
4752 odyn
->add_section_size(elfcpp::DT_PREINIT_ARRAYSZ
, *p
);
4758 // Add a DT_RPATH entry if needed.
4759 const General_options::Dir_list
& rpath(parameters
->options().rpath());
4762 std::string rpath_val
;
4763 for (General_options::Dir_list::const_iterator p
= rpath
.begin();
4767 if (rpath_val
.empty())
4768 rpath_val
= p
->name();
4771 // Eliminate duplicates.
4772 General_options::Dir_list::const_iterator q
;
4773 for (q
= rpath
.begin(); q
!= p
; ++q
)
4774 if (q
->name() == p
->name())
4779 rpath_val
+= p
->name();
4784 if (!parameters
->options().enable_new_dtags())
4785 odyn
->add_string(elfcpp::DT_RPATH
, rpath_val
);
4787 odyn
->add_string(elfcpp::DT_RUNPATH
, rpath_val
);
4790 // Look for text segments that have dynamic relocations.
4791 bool have_textrel
= false;
4792 if (!this->script_options_
->saw_sections_clause())
4794 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
4795 p
!= this->segment_list_
.end();
4798 if ((*p
)->type() == elfcpp::PT_LOAD
4799 && ((*p
)->flags() & elfcpp::PF_W
) == 0
4800 && (*p
)->has_dynamic_reloc())
4802 have_textrel
= true;
4809 // We don't know the section -> segment mapping, so we are
4810 // conservative and just look for readonly sections with
4811 // relocations. If those sections wind up in writable segments,
4812 // then we have created an unnecessary DT_TEXTREL entry.
4813 for (Section_list::const_iterator p
= this->section_list_
.begin();
4814 p
!= this->section_list_
.end();
4817 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) != 0
4818 && ((*p
)->flags() & elfcpp::SHF_WRITE
) == 0
4819 && (*p
)->has_dynamic_reloc())
4821 have_textrel
= true;
4827 if (parameters
->options().filter() != NULL
)
4828 odyn
->add_string(elfcpp::DT_FILTER
, parameters
->options().filter());
4829 if (parameters
->options().any_auxiliary())
4831 for (options::String_set::const_iterator p
=
4832 parameters
->options().auxiliary_begin();
4833 p
!= parameters
->options().auxiliary_end();
4835 odyn
->add_string(elfcpp::DT_AUXILIARY
, *p
);
4838 // Add a DT_FLAGS entry if necessary.
4839 unsigned int flags
= 0;
4842 // Add a DT_TEXTREL for compatibility with older loaders.
4843 odyn
->add_constant(elfcpp::DT_TEXTREL
, 0);
4844 flags
|= elfcpp::DF_TEXTREL
;
4846 if (parameters
->options().text())
4847 gold_error(_("read-only segment has dynamic relocations"));
4848 else if (parameters
->options().warn_shared_textrel()
4849 && parameters
->options().shared())
4850 gold_warning(_("shared library text segment is not shareable"));
4852 if (parameters
->options().shared() && this->has_static_tls())
4853 flags
|= elfcpp::DF_STATIC_TLS
;
4854 if (parameters
->options().origin())
4855 flags
|= elfcpp::DF_ORIGIN
;
4856 if (parameters
->options().Bsymbolic())
4858 flags
|= elfcpp::DF_SYMBOLIC
;
4859 // Add DT_SYMBOLIC for compatibility with older loaders.
4860 odyn
->add_constant(elfcpp::DT_SYMBOLIC
, 0);
4862 if (parameters
->options().now())
4863 flags
|= elfcpp::DF_BIND_NOW
;
4865 odyn
->add_constant(elfcpp::DT_FLAGS
, flags
);
4868 if (parameters
->options().initfirst())
4869 flags
|= elfcpp::DF_1_INITFIRST
;
4870 if (parameters
->options().interpose())
4871 flags
|= elfcpp::DF_1_INTERPOSE
;
4872 if (parameters
->options().loadfltr())
4873 flags
|= elfcpp::DF_1_LOADFLTR
;
4874 if (parameters
->options().nodefaultlib())
4875 flags
|= elfcpp::DF_1_NODEFLIB
;
4876 if (parameters
->options().nodelete())
4877 flags
|= elfcpp::DF_1_NODELETE
;
4878 if (parameters
->options().nodlopen())
4879 flags
|= elfcpp::DF_1_NOOPEN
;
4880 if (parameters
->options().nodump())
4881 flags
|= elfcpp::DF_1_NODUMP
;
4882 if (!parameters
->options().shared())
4883 flags
&= ~(elfcpp::DF_1_INITFIRST
4884 | elfcpp::DF_1_NODELETE
4885 | elfcpp::DF_1_NOOPEN
);
4886 if (parameters
->options().origin())
4887 flags
|= elfcpp::DF_1_ORIGIN
;
4888 if (parameters
->options().now())
4889 flags
|= elfcpp::DF_1_NOW
;
4890 if (parameters
->options().Bgroup())
4891 flags
|= elfcpp::DF_1_GROUP
;
4893 odyn
->add_constant(elfcpp::DT_FLAGS_1
, flags
);
4896 // Set the size of the _DYNAMIC symbol table to be the size of the
4900 Layout::set_dynamic_symbol_size(const Symbol_table
* symtab
)
4902 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
4905 odyn
->finalize_data_size();
4906 if (this->dynamic_symbol_
== NULL
)
4908 off_t data_size
= odyn
->data_size();
4909 const int size
= parameters
->target().get_size();
4911 symtab
->get_sized_symbol
<32>(this->dynamic_symbol_
)->set_symsize(data_size
);
4912 else if (size
== 64)
4913 symtab
->get_sized_symbol
<64>(this->dynamic_symbol_
)->set_symsize(data_size
);
4918 // The mapping of input section name prefixes to output section names.
4919 // In some cases one prefix is itself a prefix of another prefix; in
4920 // such a case the longer prefix must come first. These prefixes are
4921 // based on the GNU linker default ELF linker script.
4923 #define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 }
4924 #define MAPPING_INIT_EXACT(f, t) { f, 0, t, sizeof(t) - 1 }
4925 const Layout::Section_name_mapping
Layout::section_name_mapping
[] =
4927 MAPPING_INIT(".text.", ".text"),
4928 MAPPING_INIT(".rodata.", ".rodata"),
4929 MAPPING_INIT(".data.rel.ro.local.", ".data.rel.ro.local"),
4930 MAPPING_INIT_EXACT(".data.rel.ro.local", ".data.rel.ro.local"),
4931 MAPPING_INIT(".data.rel.ro.", ".data.rel.ro"),
4932 MAPPING_INIT_EXACT(".data.rel.ro", ".data.rel.ro"),
4933 MAPPING_INIT(".data.", ".data"),
4934 MAPPING_INIT(".bss.", ".bss"),
4935 MAPPING_INIT(".tdata.", ".tdata"),
4936 MAPPING_INIT(".tbss.", ".tbss"),
4937 MAPPING_INIT(".init_array.", ".init_array"),
4938 MAPPING_INIT(".fini_array.", ".fini_array"),
4939 MAPPING_INIT(".sdata.", ".sdata"),
4940 MAPPING_INIT(".sbss.", ".sbss"),
4941 // FIXME: In the GNU linker, .sbss2 and .sdata2 are handled
4942 // differently depending on whether it is creating a shared library.
4943 MAPPING_INIT(".sdata2.", ".sdata"),
4944 MAPPING_INIT(".sbss2.", ".sbss"),
4945 MAPPING_INIT(".lrodata.", ".lrodata"),
4946 MAPPING_INIT(".ldata.", ".ldata"),
4947 MAPPING_INIT(".lbss.", ".lbss"),
4948 MAPPING_INIT(".gcc_except_table.", ".gcc_except_table"),
4949 MAPPING_INIT(".gnu.linkonce.d.rel.ro.local.", ".data.rel.ro.local"),
4950 MAPPING_INIT(".gnu.linkonce.d.rel.ro.", ".data.rel.ro"),
4951 MAPPING_INIT(".gnu.linkonce.t.", ".text"),
4952 MAPPING_INIT(".gnu.linkonce.r.", ".rodata"),
4953 MAPPING_INIT(".gnu.linkonce.d.", ".data"),
4954 MAPPING_INIT(".gnu.linkonce.b.", ".bss"),
4955 MAPPING_INIT(".gnu.linkonce.s.", ".sdata"),
4956 MAPPING_INIT(".gnu.linkonce.sb.", ".sbss"),
4957 MAPPING_INIT(".gnu.linkonce.s2.", ".sdata"),
4958 MAPPING_INIT(".gnu.linkonce.sb2.", ".sbss"),
4959 MAPPING_INIT(".gnu.linkonce.wi.", ".debug_info"),
4960 MAPPING_INIT(".gnu.linkonce.td.", ".tdata"),
4961 MAPPING_INIT(".gnu.linkonce.tb.", ".tbss"),
4962 MAPPING_INIT(".gnu.linkonce.lr.", ".lrodata"),
4963 MAPPING_INIT(".gnu.linkonce.l.", ".ldata"),
4964 MAPPING_INIT(".gnu.linkonce.lb.", ".lbss"),
4965 MAPPING_INIT(".ARM.extab", ".ARM.extab"),
4966 MAPPING_INIT(".gnu.linkonce.armextab.", ".ARM.extab"),
4967 MAPPING_INIT(".ARM.exidx", ".ARM.exidx"),
4968 MAPPING_INIT(".gnu.linkonce.armexidx.", ".ARM.exidx"),
4971 #undef MAPPING_INIT_EXACT
4973 const int Layout::section_name_mapping_count
=
4974 (sizeof(Layout::section_name_mapping
)
4975 / sizeof(Layout::section_name_mapping
[0]));
4977 // Choose the output section name to use given an input section name.
4978 // Set *PLEN to the length of the name. *PLEN is initialized to the
4982 Layout::output_section_name(const Relobj
* relobj
, const char* name
,
4985 // gcc 4.3 generates the following sorts of section names when it
4986 // needs a section name specific to a function:
4992 // .data.rel.local.FN
4994 // .data.rel.ro.local.FN
5001 // The GNU linker maps all of those to the part before the .FN,
5002 // except that .data.rel.local.FN is mapped to .data, and
5003 // .data.rel.ro.local.FN is mapped to .data.rel.ro. The sections
5004 // beginning with .data.rel.ro.local are grouped together.
5006 // For an anonymous namespace, the string FN can contain a '.'.
5008 // Also of interest: .rodata.strN.N, .rodata.cstN, both of which the
5009 // GNU linker maps to .rodata.
5011 // The .data.rel.ro sections are used with -z relro. The sections
5012 // are recognized by name. We use the same names that the GNU
5013 // linker does for these sections.
5015 // It is hard to handle this in a principled way, so we don't even
5016 // try. We use a table of mappings. If the input section name is
5017 // not found in the table, we simply use it as the output section
5020 const Section_name_mapping
* psnm
= section_name_mapping
;
5021 for (int i
= 0; i
< section_name_mapping_count
; ++i
, ++psnm
)
5023 if (psnm
->fromlen
> 0)
5025 if (strncmp(name
, psnm
->from
, psnm
->fromlen
) == 0)
5027 *plen
= psnm
->tolen
;
5033 if (strcmp(name
, psnm
->from
) == 0)
5035 *plen
= psnm
->tolen
;
5041 // As an additional complication, .ctors sections are output in
5042 // either .ctors or .init_array sections, and .dtors sections are
5043 // output in either .dtors or .fini_array sections.
5044 if (is_prefix_of(".ctors.", name
) || is_prefix_of(".dtors.", name
))
5046 if (parameters
->options().ctors_in_init_array())
5049 return name
[1] == 'c' ? ".init_array" : ".fini_array";
5054 return name
[1] == 'c' ? ".ctors" : ".dtors";
5057 if (parameters
->options().ctors_in_init_array()
5058 && (strcmp(name
, ".ctors") == 0 || strcmp(name
, ".dtors") == 0))
5060 // To make .init_array/.fini_array work with gcc we must exclude
5061 // .ctors and .dtors sections from the crtbegin and crtend
5064 || (!Layout::match_file_name(relobj
, "crtbegin")
5065 && !Layout::match_file_name(relobj
, "crtend")))
5068 return name
[1] == 'c' ? ".init_array" : ".fini_array";
5075 // Return true if RELOBJ is an input file whose base name matches
5076 // FILE_NAME. The base name must have an extension of ".o", and must
5077 // be exactly FILE_NAME.o or FILE_NAME, one character, ".o". This is
5078 // to match crtbegin.o as well as crtbeginS.o without getting confused
5079 // by other possibilities. Overall matching the file name this way is
5080 // a dreadful hack, but the GNU linker does it in order to better
5081 // support gcc, and we need to be compatible.
5084 Layout::match_file_name(const Relobj
* relobj
, const char* match
)
5086 const std::string
& file_name(relobj
->name());
5087 const char* base_name
= lbasename(file_name
.c_str());
5088 size_t match_len
= strlen(match
);
5089 if (strncmp(base_name
, match
, match_len
) != 0)
5091 size_t base_len
= strlen(base_name
);
5092 if (base_len
!= match_len
+ 2 && base_len
!= match_len
+ 3)
5094 return memcmp(base_name
+ base_len
- 2, ".o", 2) == 0;
5097 // Check if a comdat group or .gnu.linkonce section with the given
5098 // NAME is selected for the link. If there is already a section,
5099 // *KEPT_SECTION is set to point to the existing section and the
5100 // function returns false. Otherwise, OBJECT, SHNDX, IS_COMDAT, and
5101 // IS_GROUP_NAME are recorded for this NAME in the layout object,
5102 // *KEPT_SECTION is set to the internal copy and the function returns
5106 Layout::find_or_add_kept_section(const std::string
& name
,
5111 Kept_section
** kept_section
)
5113 // It's normal to see a couple of entries here, for the x86 thunk
5114 // sections. If we see more than a few, we're linking a C++
5115 // program, and we resize to get more space to minimize rehashing.
5116 if (this->signatures_
.size() > 4
5117 && !this->resized_signatures_
)
5119 reserve_unordered_map(&this->signatures_
,
5120 this->number_of_input_files_
* 64);
5121 this->resized_signatures_
= true;
5124 Kept_section candidate
;
5125 std::pair
<Signatures::iterator
, bool> ins
=
5126 this->signatures_
.insert(std::make_pair(name
, candidate
));
5128 if (kept_section
!= NULL
)
5129 *kept_section
= &ins
.first
->second
;
5132 // This is the first time we've seen this signature.
5133 ins
.first
->second
.set_object(object
);
5134 ins
.first
->second
.set_shndx(shndx
);
5136 ins
.first
->second
.set_is_comdat();
5138 ins
.first
->second
.set_is_group_name();
5142 // We have already seen this signature.
5144 if (ins
.first
->second
.is_group_name())
5146 // We've already seen a real section group with this signature.
5147 // If the kept group is from a plugin object, and we're in the
5148 // replacement phase, accept the new one as a replacement.
5149 if (ins
.first
->second
.object() == NULL
5150 && parameters
->options().plugins()->in_replacement_phase())
5152 ins
.first
->second
.set_object(object
);
5153 ins
.first
->second
.set_shndx(shndx
);
5158 else if (is_group_name
)
5160 // This is a real section group, and we've already seen a
5161 // linkonce section with this signature. Record that we've seen
5162 // a section group, and don't include this section group.
5163 ins
.first
->second
.set_is_group_name();
5168 // We've already seen a linkonce section and this is a linkonce
5169 // section. These don't block each other--this may be the same
5170 // symbol name with different section types.
5175 // Store the allocated sections into the section list.
5178 Layout::get_allocated_sections(Section_list
* section_list
) const
5180 for (Section_list::const_iterator p
= this->section_list_
.begin();
5181 p
!= this->section_list_
.end();
5183 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) != 0)
5184 section_list
->push_back(*p
);
5187 // Store the executable sections into the section list.
5190 Layout::get_executable_sections(Section_list
* section_list
) const
5192 for (Section_list::const_iterator p
= this->section_list_
.begin();
5193 p
!= this->section_list_
.end();
5195 if (((*p
)->flags() & (elfcpp::SHF_ALLOC
| elfcpp::SHF_EXECINSTR
))
5196 == (elfcpp::SHF_ALLOC
| elfcpp::SHF_EXECINSTR
))
5197 section_list
->push_back(*p
);
5200 // Create an output segment.
5203 Layout::make_output_segment(elfcpp::Elf_Word type
, elfcpp::Elf_Word flags
)
5205 gold_assert(!parameters
->options().relocatable());
5206 Output_segment
* oseg
= new Output_segment(type
, flags
);
5207 this->segment_list_
.push_back(oseg
);
5209 if (type
== elfcpp::PT_TLS
)
5210 this->tls_segment_
= oseg
;
5211 else if (type
== elfcpp::PT_GNU_RELRO
)
5212 this->relro_segment_
= oseg
;
5213 else if (type
== elfcpp::PT_INTERP
)
5214 this->interp_segment_
= oseg
;
5219 // Return the file offset of the normal symbol table.
5222 Layout::symtab_section_offset() const
5224 if (this->symtab_section_
!= NULL
)
5225 return this->symtab_section_
->offset();
5229 // Return the section index of the normal symbol table. It may have
5230 // been stripped by the -s/--strip-all option.
5233 Layout::symtab_section_shndx() const
5235 if (this->symtab_section_
!= NULL
)
5236 return this->symtab_section_
->out_shndx();
5240 // Write out the Output_sections. Most won't have anything to write,
5241 // since most of the data will come from input sections which are
5242 // handled elsewhere. But some Output_sections do have Output_data.
5245 Layout::write_output_sections(Output_file
* of
) const
5247 for (Section_list::const_iterator p
= this->section_list_
.begin();
5248 p
!= this->section_list_
.end();
5251 if (!(*p
)->after_input_sections())
5256 // Write out data not associated with a section or the symbol table.
5259 Layout::write_data(const Symbol_table
* symtab
, Output_file
* of
) const
5261 if (!parameters
->options().strip_all())
5263 const Output_section
* symtab_section
= this->symtab_section_
;
5264 for (Section_list::const_iterator p
= this->section_list_
.begin();
5265 p
!= this->section_list_
.end();
5268 if ((*p
)->needs_symtab_index())
5270 gold_assert(symtab_section
!= NULL
);
5271 unsigned int index
= (*p
)->symtab_index();
5272 gold_assert(index
> 0 && index
!= -1U);
5273 off_t off
= (symtab_section
->offset()
5274 + index
* symtab_section
->entsize());
5275 symtab
->write_section_symbol(*p
, this->symtab_xindex_
, of
, off
);
5280 const Output_section
* dynsym_section
= this->dynsym_section_
;
5281 for (Section_list::const_iterator p
= this->section_list_
.begin();
5282 p
!= this->section_list_
.end();
5285 if ((*p
)->needs_dynsym_index())
5287 gold_assert(dynsym_section
!= NULL
);
5288 unsigned int index
= (*p
)->dynsym_index();
5289 gold_assert(index
> 0 && index
!= -1U);
5290 off_t off
= (dynsym_section
->offset()
5291 + index
* dynsym_section
->entsize());
5292 symtab
->write_section_symbol(*p
, this->dynsym_xindex_
, of
, off
);
5296 // Write out the Output_data which are not in an Output_section.
5297 for (Data_list::const_iterator p
= this->special_output_list_
.begin();
5298 p
!= this->special_output_list_
.end();
5302 // Write out the Output_data which are not in an Output_section
5303 // and are regenerated in each iteration of relaxation.
5304 for (Data_list::const_iterator p
= this->relax_output_list_
.begin();
5305 p
!= this->relax_output_list_
.end();
5310 // Write out the Output_sections which can only be written after the
5311 // input sections are complete.
5314 Layout::write_sections_after_input_sections(Output_file
* of
)
5316 // Determine the final section offsets, and thus the final output
5317 // file size. Note we finalize the .shstrab last, to allow the
5318 // after_input_section sections to modify their section-names before
5320 if (this->any_postprocessing_sections_
)
5322 off_t off
= this->output_file_size_
;
5323 off
= this->set_section_offsets(off
, POSTPROCESSING_SECTIONS_PASS
);
5325 // Now that we've finalized the names, we can finalize the shstrab.
5327 this->set_section_offsets(off
,
5328 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
);
5330 if (off
> this->output_file_size_
)
5333 this->output_file_size_
= off
;
5337 for (Section_list::const_iterator p
= this->section_list_
.begin();
5338 p
!= this->section_list_
.end();
5341 if ((*p
)->after_input_sections())
5345 this->section_headers_
->write(of
);
5348 // Build IDs can be computed as a "flat" sha1 or md5 of a string of bytes,
5349 // or as a "tree" where each chunk of the string is hashed and then those
5350 // hashes are put into a (much smaller) string which is hashed with sha1.
5351 // We compute a checksum over the entire file because that is simplest.
5354 Layout::queue_build_id_tasks(Workqueue
* workqueue
, Task_token
* build_id_blocker
,
5357 const size_t filesize
= (this->output_file_size() <= 0 ? 0
5358 : static_cast<size_t>(this->output_file_size()));
5359 if (this->build_id_note_
!= NULL
5360 && strcmp(parameters
->options().build_id(), "tree") == 0
5361 && parameters
->options().build_id_chunk_size_for_treehash() > 0
5364 parameters
->options().build_id_min_file_size_for_treehash()))
5366 static const size_t MD5_OUTPUT_SIZE_IN_BYTES
= 16;
5367 const size_t chunk_size
=
5368 parameters
->options().build_id_chunk_size_for_treehash();
5369 const size_t num_hashes
= ((filesize
- 1) / chunk_size
) + 1;
5370 Task_token
* post_hash_tasks_blocker
= new Task_token(true);
5371 post_hash_tasks_blocker
->add_blockers(num_hashes
);
5372 this->size_of_array_of_hashes_
= num_hashes
* MD5_OUTPUT_SIZE_IN_BYTES
;
5373 const unsigned char* src
= of
->get_input_view(0, filesize
);
5374 this->input_view_
= src
;
5375 unsigned char *dst
= new unsigned char[this->size_of_array_of_hashes_
];
5376 this->array_of_hashes_
= dst
;
5377 for (size_t i
= 0, src_offset
= 0; i
< num_hashes
;
5378 i
++, dst
+= MD5_OUTPUT_SIZE_IN_BYTES
, src_offset
+= chunk_size
)
5380 size_t size
= std::min(chunk_size
, filesize
- src_offset
);
5381 workqueue
->queue(new Hash_task(src
+ src_offset
,
5385 post_hash_tasks_blocker
));
5387 return post_hash_tasks_blocker
;
5389 return build_id_blocker
;
5392 // If a tree-style build ID was requested, the parallel part of that computation
5393 // is already done, and the final hash-of-hashes is computed here. For other
5394 // types of build IDs, all the work is done here.
5397 Layout::write_build_id(Output_file
* of
) const
5399 if (this->build_id_note_
== NULL
)
5402 unsigned char* ov
= of
->get_output_view(this->build_id_note_
->offset(),
5403 this->build_id_note_
->data_size());
5405 if (this->array_of_hashes_
== NULL
)
5407 const size_t output_file_size
= this->output_file_size();
5408 const unsigned char* iv
= of
->get_input_view(0, output_file_size
);
5409 const char* style
= parameters
->options().build_id();
5411 // If we get here with style == "tree" then the output must be
5412 // too small for chunking, and we use SHA-1 in that case.
5413 if ((strcmp(style
, "sha1") == 0) || (strcmp(style
, "tree") == 0))
5414 sha1_buffer(reinterpret_cast<const char*>(iv
), output_file_size
, ov
);
5415 else if (strcmp(style
, "md5") == 0)
5416 md5_buffer(reinterpret_cast<const char*>(iv
), output_file_size
, ov
);
5420 of
->free_input_view(0, output_file_size
, iv
);
5424 // Non-overlapping substrings of the output file have been hashed.
5425 // Compute SHA-1 hash of the hashes.
5426 sha1_buffer(reinterpret_cast<const char*>(this->array_of_hashes_
),
5427 this->size_of_array_of_hashes_
, ov
);
5428 delete[] this->array_of_hashes_
;
5429 of
->free_input_view(0, this->output_file_size(), this->input_view_
);
5432 of
->write_output_view(this->build_id_note_
->offset(),
5433 this->build_id_note_
->data_size(),
5437 // Write out a binary file. This is called after the link is
5438 // complete. IN is the temporary output file we used to generate the
5439 // ELF code. We simply walk through the segments, read them from
5440 // their file offset in IN, and write them to their load address in
5441 // the output file. FIXME: with a bit more work, we could support
5442 // S-records and/or Intel hex format here.
5445 Layout::write_binary(Output_file
* in
) const
5447 gold_assert(parameters
->options().oformat_enum()
5448 == General_options::OBJECT_FORMAT_BINARY
);
5450 // Get the size of the binary file.
5451 uint64_t max_load_address
= 0;
5452 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
5453 p
!= this->segment_list_
.end();
5456 if ((*p
)->type() == elfcpp::PT_LOAD
&& (*p
)->filesz() > 0)
5458 uint64_t max_paddr
= (*p
)->paddr() + (*p
)->filesz();
5459 if (max_paddr
> max_load_address
)
5460 max_load_address
= max_paddr
;
5464 Output_file
out(parameters
->options().output_file_name());
5465 out
.open(max_load_address
);
5467 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
5468 p
!= this->segment_list_
.end();
5471 if ((*p
)->type() == elfcpp::PT_LOAD
&& (*p
)->filesz() > 0)
5473 const unsigned char* vin
= in
->get_input_view((*p
)->offset(),
5475 unsigned char* vout
= out
.get_output_view((*p
)->paddr(),
5477 memcpy(vout
, vin
, (*p
)->filesz());
5478 out
.write_output_view((*p
)->paddr(), (*p
)->filesz(), vout
);
5479 in
->free_input_view((*p
)->offset(), (*p
)->filesz(), vin
);
5486 // Print the output sections to the map file.
5489 Layout::print_to_mapfile(Mapfile
* mapfile
) const
5491 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
5492 p
!= this->segment_list_
.end();
5494 (*p
)->print_sections_to_mapfile(mapfile
);
5497 // Print statistical information to stderr. This is used for --stats.
5500 Layout::print_stats() const
5502 this->namepool_
.print_stats("section name pool");
5503 this->sympool_
.print_stats("output symbol name pool");
5504 this->dynpool_
.print_stats("dynamic name pool");
5506 for (Section_list::const_iterator p
= this->section_list_
.begin();
5507 p
!= this->section_list_
.end();
5509 (*p
)->print_merge_stats();
5512 // Write_sections_task methods.
5514 // We can always run this task.
5517 Write_sections_task::is_runnable()
5522 // We need to unlock both OUTPUT_SECTIONS_BLOCKER and FINAL_BLOCKER
5526 Write_sections_task::locks(Task_locker
* tl
)
5528 tl
->add(this, this->output_sections_blocker_
);
5529 tl
->add(this, this->final_blocker_
);
5532 // Run the task--write out the data.
5535 Write_sections_task::run(Workqueue
*)
5537 this->layout_
->write_output_sections(this->of_
);
5540 // Write_data_task methods.
5542 // We can always run this task.
5545 Write_data_task::is_runnable()
5550 // We need to unlock FINAL_BLOCKER when finished.
5553 Write_data_task::locks(Task_locker
* tl
)
5555 tl
->add(this, this->final_blocker_
);
5558 // Run the task--write out the data.
5561 Write_data_task::run(Workqueue
*)
5563 this->layout_
->write_data(this->symtab_
, this->of_
);
5566 // Write_symbols_task methods.
5568 // We can always run this task.
5571 Write_symbols_task::is_runnable()
5576 // We need to unlock FINAL_BLOCKER when finished.
5579 Write_symbols_task::locks(Task_locker
* tl
)
5581 tl
->add(this, this->final_blocker_
);
5584 // Run the task--write out the symbols.
5587 Write_symbols_task::run(Workqueue
*)
5589 this->symtab_
->write_globals(this->sympool_
, this->dynpool_
,
5590 this->layout_
->symtab_xindex(),
5591 this->layout_
->dynsym_xindex(), this->of_
);
5594 // Write_after_input_sections_task methods.
5596 // We can only run this task after the input sections have completed.
5599 Write_after_input_sections_task::is_runnable()
5601 if (this->input_sections_blocker_
->is_blocked())
5602 return this->input_sections_blocker_
;
5606 // We need to unlock FINAL_BLOCKER when finished.
5609 Write_after_input_sections_task::locks(Task_locker
* tl
)
5611 tl
->add(this, this->final_blocker_
);
5617 Write_after_input_sections_task::run(Workqueue
*)
5619 this->layout_
->write_sections_after_input_sections(this->of_
);
5622 // Close_task_runner methods.
5624 // Finish up the build ID computation, if necessary, and write a binary file,
5625 // if necessary. Then close the output file.
5628 Close_task_runner::run(Workqueue
*, const Task
*)
5630 // At this point the multi-threaded part of the build ID computation,
5631 // if any, is done. See queue_build_id_tasks().
5632 this->layout_
->write_build_id(this->of_
);
5634 // If we've been asked to create a binary file, we do so here.
5635 if (this->options_
->oformat_enum() != General_options::OBJECT_FORMAT_ELF
)
5636 this->layout_
->write_binary(this->of_
);
5641 // Instantiate the templates we need. We could use the configure
5642 // script to restrict this to only the ones for implemented targets.
5644 #ifdef HAVE_TARGET_32_LITTLE
5647 Layout::init_fixed_output_section
<32, false>(
5649 elfcpp::Shdr
<32, false>& shdr
);
5652 #ifdef HAVE_TARGET_32_BIG
5655 Layout::init_fixed_output_section
<32, true>(
5657 elfcpp::Shdr
<32, true>& shdr
);
5660 #ifdef HAVE_TARGET_64_LITTLE
5663 Layout::init_fixed_output_section
<64, false>(
5665 elfcpp::Shdr
<64, false>& shdr
);
5668 #ifdef HAVE_TARGET_64_BIG
5671 Layout::init_fixed_output_section
<64, true>(
5673 elfcpp::Shdr
<64, true>& shdr
);
5676 #ifdef HAVE_TARGET_32_LITTLE
5679 Layout::layout
<32, false>(Sized_relobj_file
<32, false>* object
,
5682 const elfcpp::Shdr
<32, false>& shdr
,
5683 unsigned int, unsigned int, off_t
*);
5686 #ifdef HAVE_TARGET_32_BIG
5689 Layout::layout
<32, true>(Sized_relobj_file
<32, true>* object
,
5692 const elfcpp::Shdr
<32, true>& shdr
,
5693 unsigned int, unsigned int, off_t
*);
5696 #ifdef HAVE_TARGET_64_LITTLE
5699 Layout::layout
<64, false>(Sized_relobj_file
<64, false>* object
,
5702 const elfcpp::Shdr
<64, false>& shdr
,
5703 unsigned int, unsigned int, off_t
*);
5706 #ifdef HAVE_TARGET_64_BIG
5709 Layout::layout
<64, true>(Sized_relobj_file
<64, true>* object
,
5712 const elfcpp::Shdr
<64, true>& shdr
,
5713 unsigned int, unsigned int, off_t
*);
5716 #ifdef HAVE_TARGET_32_LITTLE
5719 Layout::layout_reloc
<32, false>(Sized_relobj_file
<32, false>* object
,
5720 unsigned int reloc_shndx
,
5721 const elfcpp::Shdr
<32, false>& shdr
,
5722 Output_section
* data_section
,
5723 Relocatable_relocs
* rr
);
5726 #ifdef HAVE_TARGET_32_BIG
5729 Layout::layout_reloc
<32, true>(Sized_relobj_file
<32, true>* object
,
5730 unsigned int reloc_shndx
,
5731 const elfcpp::Shdr
<32, true>& shdr
,
5732 Output_section
* data_section
,
5733 Relocatable_relocs
* rr
);
5736 #ifdef HAVE_TARGET_64_LITTLE
5739 Layout::layout_reloc
<64, false>(Sized_relobj_file
<64, false>* object
,
5740 unsigned int reloc_shndx
,
5741 const elfcpp::Shdr
<64, false>& shdr
,
5742 Output_section
* data_section
,
5743 Relocatable_relocs
* rr
);
5746 #ifdef HAVE_TARGET_64_BIG
5749 Layout::layout_reloc
<64, true>(Sized_relobj_file
<64, true>* object
,
5750 unsigned int reloc_shndx
,
5751 const elfcpp::Shdr
<64, true>& shdr
,
5752 Output_section
* data_section
,
5753 Relocatable_relocs
* rr
);
5756 #ifdef HAVE_TARGET_32_LITTLE
5759 Layout::layout_group
<32, false>(Symbol_table
* symtab
,
5760 Sized_relobj_file
<32, false>* object
,
5762 const char* group_section_name
,
5763 const char* signature
,
5764 const elfcpp::Shdr
<32, false>& shdr
,
5765 elfcpp::Elf_Word flags
,
5766 std::vector
<unsigned int>* shndxes
);
5769 #ifdef HAVE_TARGET_32_BIG
5772 Layout::layout_group
<32, true>(Symbol_table
* symtab
,
5773 Sized_relobj_file
<32, true>* object
,
5775 const char* group_section_name
,
5776 const char* signature
,
5777 const elfcpp::Shdr
<32, true>& shdr
,
5778 elfcpp::Elf_Word flags
,
5779 std::vector
<unsigned int>* shndxes
);
5782 #ifdef HAVE_TARGET_64_LITTLE
5785 Layout::layout_group
<64, false>(Symbol_table
* symtab
,
5786 Sized_relobj_file
<64, false>* object
,
5788 const char* group_section_name
,
5789 const char* signature
,
5790 const elfcpp::Shdr
<64, false>& shdr
,
5791 elfcpp::Elf_Word flags
,
5792 std::vector
<unsigned int>* shndxes
);
5795 #ifdef HAVE_TARGET_64_BIG
5798 Layout::layout_group
<64, true>(Symbol_table
* symtab
,
5799 Sized_relobj_file
<64, true>* object
,
5801 const char* group_section_name
,
5802 const char* signature
,
5803 const elfcpp::Shdr
<64, true>& shdr
,
5804 elfcpp::Elf_Word flags
,
5805 std::vector
<unsigned int>* shndxes
);
5808 #ifdef HAVE_TARGET_32_LITTLE
5811 Layout::layout_eh_frame
<32, false>(Sized_relobj_file
<32, false>* object
,
5812 const unsigned char* symbols
,
5814 const unsigned char* symbol_names
,
5815 off_t symbol_names_size
,
5817 const elfcpp::Shdr
<32, false>& shdr
,
5818 unsigned int reloc_shndx
,
5819 unsigned int reloc_type
,
5823 #ifdef HAVE_TARGET_32_BIG
5826 Layout::layout_eh_frame
<32, true>(Sized_relobj_file
<32, true>* object
,
5827 const unsigned char* symbols
,
5829 const unsigned char* symbol_names
,
5830 off_t symbol_names_size
,
5832 const elfcpp::Shdr
<32, true>& shdr
,
5833 unsigned int reloc_shndx
,
5834 unsigned int reloc_type
,
5838 #ifdef HAVE_TARGET_64_LITTLE
5841 Layout::layout_eh_frame
<64, false>(Sized_relobj_file
<64, false>* object
,
5842 const unsigned char* symbols
,
5844 const unsigned char* symbol_names
,
5845 off_t symbol_names_size
,
5847 const elfcpp::Shdr
<64, false>& shdr
,
5848 unsigned int reloc_shndx
,
5849 unsigned int reloc_type
,
5853 #ifdef HAVE_TARGET_64_BIG
5856 Layout::layout_eh_frame
<64, true>(Sized_relobj_file
<64, true>* object
,
5857 const unsigned char* symbols
,
5859 const unsigned char* symbol_names
,
5860 off_t symbol_names_size
,
5862 const elfcpp::Shdr
<64, true>& shdr
,
5863 unsigned int reloc_shndx
,
5864 unsigned int reloc_type
,
5868 #ifdef HAVE_TARGET_32_LITTLE
5871 Layout::add_to_gdb_index(bool is_type_unit
,
5872 Sized_relobj
<32, false>* object
,
5873 const unsigned char* symbols
,
5876 unsigned int reloc_shndx
,
5877 unsigned int reloc_type
);
5880 #ifdef HAVE_TARGET_32_BIG
5883 Layout::add_to_gdb_index(bool is_type_unit
,
5884 Sized_relobj
<32, true>* object
,
5885 const unsigned char* symbols
,
5888 unsigned int reloc_shndx
,
5889 unsigned int reloc_type
);
5892 #ifdef HAVE_TARGET_64_LITTLE
5895 Layout::add_to_gdb_index(bool is_type_unit
,
5896 Sized_relobj
<64, false>* object
,
5897 const unsigned char* symbols
,
5900 unsigned int reloc_shndx
,
5901 unsigned int reloc_type
);
5904 #ifdef HAVE_TARGET_64_BIG
5907 Layout::add_to_gdb_index(bool is_type_unit
,
5908 Sized_relobj
<64, true>* object
,
5909 const unsigned char* symbols
,
5912 unsigned int reloc_shndx
,
5913 unsigned int reloc_type
);
5916 } // End namespace gold.