1 // layout.cc -- lay out output file sections for gold
3 // Copyright 2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
4 // Written by Ian Lance Taylor <iant@google.com>.
6 // This file is part of gold.
8 // This program is free software; you can redistribute it and/or modify
9 // it under the terms of the GNU General Public License as published by
10 // the Free Software Foundation; either version 3 of the License, or
11 // (at your option) any later version.
13 // This program is distributed in the hope that it will be useful,
14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 // GNU General Public License for more details.
18 // You should have received a copy of the GNU General Public License
19 // along with this program; if not, write to the Free Software
20 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
21 // MA 02110-1301, USA.
34 #include "libiberty.h"
38 #include "parameters.h"
42 #include "script-sections.h"
47 #include "compressed_output.h"
48 #include "reduced_debug_output.h"
51 #include "descriptors.h"
53 #include "incremental.h"
61 // The total number of free lists used.
62 unsigned int Free_list::num_lists
= 0;
63 // The total number of free list nodes used.
64 unsigned int Free_list::num_nodes
= 0;
65 // The total number of calls to Free_list::remove.
66 unsigned int Free_list::num_removes
= 0;
67 // The total number of nodes visited during calls to Free_list::remove.
68 unsigned int Free_list::num_remove_visits
= 0;
69 // The total number of calls to Free_list::allocate.
70 unsigned int Free_list::num_allocates
= 0;
71 // The total number of nodes visited during calls to Free_list::allocate.
72 unsigned int Free_list::num_allocate_visits
= 0;
74 // Initialize the free list. Creates a single free list node that
75 // describes the entire region of length LEN. If EXTEND is true,
76 // allocate() is allowed to extend the region beyond its initial
80 Free_list::init(off_t len
, bool extend
)
82 this->list_
.push_front(Free_list_node(0, len
));
83 this->last_remove_
= this->list_
.begin();
84 this->extend_
= extend
;
86 ++Free_list::num_lists
;
87 ++Free_list::num_nodes
;
90 // Remove a chunk from the free list. Because we start with a single
91 // node that covers the entire section, and remove chunks from it one
92 // at a time, we do not need to coalesce chunks or handle cases that
93 // span more than one free node. We expect to remove chunks from the
94 // free list in order, and we expect to have only a few chunks of free
95 // space left (corresponding to files that have changed since the last
96 // incremental link), so a simple linear list should provide sufficient
100 Free_list::remove(off_t start
, off_t end
)
104 gold_assert(start
< end
);
106 ++Free_list::num_removes
;
108 Iterator p
= this->last_remove_
;
109 if (p
->start_
> start
)
110 p
= this->list_
.begin();
112 for (; p
!= this->list_
.end(); ++p
)
114 ++Free_list::num_remove_visits
;
115 // Find a node that wholly contains the indicated region.
116 if (p
->start_
<= start
&& p
->end_
>= end
)
118 // Case 1: the indicated region spans the whole node.
119 // Add some fuzz to avoid creating tiny free chunks.
120 if (p
->start_
+ 3 >= start
&& p
->end_
<= end
+ 3)
121 p
= this->list_
.erase(p
);
122 // Case 2: remove a chunk from the start of the node.
123 else if (p
->start_
+ 3 >= start
)
125 // Case 3: remove a chunk from the end of the node.
126 else if (p
->end_
<= end
+ 3)
128 // Case 4: remove a chunk from the middle, and split
129 // the node into two.
132 Free_list_node
newnode(p
->start_
, start
);
134 this->list_
.insert(p
, newnode
);
135 ++Free_list::num_nodes
;
137 this->last_remove_
= p
;
142 // Did not find a node containing the given chunk. This could happen
143 // because a small chunk was already removed due to the fuzz.
144 gold_debug(DEBUG_INCREMENTAL
,
145 "Free_list::remove(%d,%d) not found",
146 static_cast<int>(start
), static_cast<int>(end
));
149 // Allocate a chunk of size LEN from the free list. Returns -1ULL
150 // if a sufficiently large chunk of free space is not found.
151 // We use a simple first-fit algorithm.
154 Free_list::allocate(off_t len
, uint64_t align
, off_t minoff
)
156 gold_debug(DEBUG_INCREMENTAL
,
157 "Free_list::allocate(%08lx, %d, %08lx)",
158 static_cast<long>(len
), static_cast<int>(align
),
159 static_cast<long>(minoff
));
161 return align_address(minoff
, align
);
163 ++Free_list::num_allocates
;
165 for (Iterator p
= this->list_
.begin(); p
!= this->list_
.end(); ++p
)
167 ++Free_list::num_allocate_visits
;
168 off_t start
= p
->start_
> minoff
? p
->start_
: minoff
;
169 start
= align_address(start
, align
);
170 off_t end
= start
+ len
;
173 if (p
->start_
+ 3 >= start
&& p
->end_
<= end
+ 3)
174 this->list_
.erase(p
);
175 else if (p
->start_
+ 3 >= start
)
177 else if (p
->end_
<= end
+ 3)
181 Free_list_node
newnode(p
->start_
, start
);
183 this->list_
.insert(p
, newnode
);
184 ++Free_list::num_nodes
;
192 // Dump the free list (for debugging).
196 gold_info("Free list:\n start end length\n");
197 for (Iterator p
= this->list_
.begin(); p
!= this->list_
.end(); ++p
)
198 gold_info(" %08lx %08lx %08lx", static_cast<long>(p
->start_
),
199 static_cast<long>(p
->end_
),
200 static_cast<long>(p
->end_
- p
->start_
));
203 // Print the statistics for the free lists.
205 Free_list::print_stats()
207 fprintf(stderr
, _("%s: total free lists: %u\n"),
208 program_name
, Free_list::num_lists
);
209 fprintf(stderr
, _("%s: total free list nodes: %u\n"),
210 program_name
, Free_list::num_nodes
);
211 fprintf(stderr
, _("%s: calls to Free_list::remove: %u\n"),
212 program_name
, Free_list::num_removes
);
213 fprintf(stderr
, _("%s: nodes visited: %u\n"),
214 program_name
, Free_list::num_remove_visits
);
215 fprintf(stderr
, _("%s: calls to Free_list::allocate: %u\n"),
216 program_name
, Free_list::num_allocates
);
217 fprintf(stderr
, _("%s: nodes visited: %u\n"),
218 program_name
, Free_list::num_allocate_visits
);
221 // Layout::Relaxation_debug_check methods.
223 // Check that sections and special data are in reset states.
224 // We do not save states for Output_sections and special Output_data.
225 // So we check that they have not assigned any addresses or offsets.
226 // clean_up_after_relaxation simply resets their addresses and offsets.
228 Layout::Relaxation_debug_check::check_output_data_for_reset_values(
229 const Layout::Section_list
& sections
,
230 const Layout::Data_list
& special_outputs
)
232 for(Layout::Section_list::const_iterator p
= sections
.begin();
235 gold_assert((*p
)->address_and_file_offset_have_reset_values());
237 for(Layout::Data_list::const_iterator p
= special_outputs
.begin();
238 p
!= special_outputs
.end();
240 gold_assert((*p
)->address_and_file_offset_have_reset_values());
243 // Save information of SECTIONS for checking later.
246 Layout::Relaxation_debug_check::read_sections(
247 const Layout::Section_list
& sections
)
249 for(Layout::Section_list::const_iterator p
= sections
.begin();
253 Output_section
* os
= *p
;
255 info
.output_section
= os
;
256 info
.address
= os
->is_address_valid() ? os
->address() : 0;
257 info
.data_size
= os
->is_data_size_valid() ? os
->data_size() : -1;
258 info
.offset
= os
->is_offset_valid()? os
->offset() : -1 ;
259 this->section_infos_
.push_back(info
);
263 // Verify SECTIONS using previously recorded information.
266 Layout::Relaxation_debug_check::verify_sections(
267 const Layout::Section_list
& sections
)
270 for(Layout::Section_list::const_iterator p
= sections
.begin();
274 Output_section
* os
= *p
;
275 uint64_t address
= os
->is_address_valid() ? os
->address() : 0;
276 off_t data_size
= os
->is_data_size_valid() ? os
->data_size() : -1;
277 off_t offset
= os
->is_offset_valid()? os
->offset() : -1 ;
279 if (i
>= this->section_infos_
.size())
281 gold_fatal("Section_info of %s missing.\n", os
->name());
283 const Section_info
& info
= this->section_infos_
[i
];
284 if (os
!= info
.output_section
)
285 gold_fatal("Section order changed. Expecting %s but see %s\n",
286 info
.output_section
->name(), os
->name());
287 if (address
!= info
.address
288 || data_size
!= info
.data_size
289 || offset
!= info
.offset
)
290 gold_fatal("Section %s changed.\n", os
->name());
294 // Layout_task_runner methods.
296 // Lay out the sections. This is called after all the input objects
300 Layout_task_runner::run(Workqueue
* workqueue
, const Task
* task
)
302 Layout
* layout
= this->layout_
;
303 off_t file_size
= layout
->finalize(this->input_objects_
,
308 // Now we know the final size of the output file and we know where
309 // each piece of information goes.
311 if (this->mapfile_
!= NULL
)
313 this->mapfile_
->print_discarded_sections(this->input_objects_
);
314 layout
->print_to_mapfile(this->mapfile_
);
318 if (layout
->incremental_base() == NULL
)
320 of
= new Output_file(parameters
->options().output_file_name());
321 if (this->options_
.oformat_enum() != General_options::OBJECT_FORMAT_ELF
)
322 of
->set_is_temporary();
327 of
= layout
->incremental_base()->output_file();
329 // Apply the incremental relocations for symbols whose values
330 // have changed. We do this before we resize the file and start
331 // writing anything else to it, so that we can read the old
332 // incremental information from the file before (possibly)
334 if (parameters
->incremental_update())
335 layout
->incremental_base()->apply_incremental_relocs(this->symtab_
,
339 of
->resize(file_size
);
342 // Queue up the final set of tasks.
343 gold::queue_final_tasks(this->options_
, this->input_objects_
,
344 this->symtab_
, layout
, workqueue
, of
);
349 Layout::Layout(int number_of_input_files
, Script_options
* script_options
)
350 : number_of_input_files_(number_of_input_files
),
351 script_options_(script_options
),
359 unattached_section_list_(),
360 special_output_list_(),
361 section_headers_(NULL
),
363 relro_segment_(NULL
),
364 interp_segment_(NULL
),
366 symtab_section_(NULL
),
367 symtab_xindex_(NULL
),
368 dynsym_section_(NULL
),
369 dynsym_xindex_(NULL
),
370 dynamic_section_(NULL
),
371 dynamic_symbol_(NULL
),
373 eh_frame_section_(NULL
),
374 eh_frame_data_(NULL
),
375 added_eh_frame_data_(false),
376 eh_frame_hdr_section_(NULL
),
377 build_id_note_(NULL
),
381 output_file_size_(-1),
382 have_added_input_section_(false),
383 sections_are_attached_(false),
384 input_requires_executable_stack_(false),
385 input_with_gnu_stack_note_(false),
386 input_without_gnu_stack_note_(false),
387 has_static_tls_(false),
388 any_postprocessing_sections_(false),
389 resized_signatures_(false),
390 have_stabstr_section_(false),
391 incremental_inputs_(NULL
),
392 record_output_section_data_from_script_(false),
393 script_output_section_data_list_(),
394 segment_states_(NULL
),
395 relaxation_debug_check_(NULL
),
396 incremental_base_(NULL
),
399 // Make space for more than enough segments for a typical file.
400 // This is just for efficiency--it's OK if we wind up needing more.
401 this->segment_list_
.reserve(12);
403 // We expect two unattached Output_data objects: the file header and
404 // the segment headers.
405 this->special_output_list_
.reserve(2);
407 // Initialize structure needed for an incremental build.
408 if (parameters
->incremental())
409 this->incremental_inputs_
= new Incremental_inputs
;
411 // The section name pool is worth optimizing in all cases, because
412 // it is small, but there are often overlaps due to .rel sections.
413 this->namepool_
.set_optimize();
416 // For incremental links, record the base file to be modified.
419 Layout::set_incremental_base(Incremental_binary
* base
)
421 this->incremental_base_
= base
;
422 this->free_list_
.init(base
->output_file()->filesize(), true);
425 // Hash a key we use to look up an output section mapping.
428 Layout::Hash_key::operator()(const Layout::Key
& k
) const
430 return k
.first
+ k
.second
.first
+ k
.second
.second
;
433 // Returns whether the given section is in the list of
434 // debug-sections-used-by-some-version-of-gdb. Currently,
435 // we've checked versions of gdb up to and including 6.7.1.
437 static const char* gdb_sections
[] =
439 // ".debug_aranges", // not used by gdb as of 6.7.1
446 // ".debug_pubnames", // not used by gdb as of 6.7.1
451 static const char* lines_only_debug_sections
[] =
453 // ".debug_aranges", // not used by gdb as of 6.7.1
460 // ".debug_pubnames", // not used by gdb as of 6.7.1
466 is_gdb_debug_section(const char* str
)
468 // We can do this faster: binary search or a hashtable. But why bother?
469 for (size_t i
= 0; i
< sizeof(gdb_sections
)/sizeof(*gdb_sections
); ++i
)
470 if (strcmp(str
, gdb_sections
[i
]) == 0)
476 is_lines_only_debug_section(const char* str
)
478 // We can do this faster: binary search or a hashtable. But why bother?
480 i
< sizeof(lines_only_debug_sections
)/sizeof(*lines_only_debug_sections
);
482 if (strcmp(str
, lines_only_debug_sections
[i
]) == 0)
487 // Sometimes we compress sections. This is typically done for
488 // sections that are not part of normal program execution (such as
489 // .debug_* sections), and where the readers of these sections know
490 // how to deal with compressed sections. This routine doesn't say for
491 // certain whether we'll compress -- it depends on commandline options
492 // as well -- just whether this section is a candidate for compression.
493 // (The Output_compressed_section class decides whether to compress
494 // a given section, and picks the name of the compressed section.)
497 is_compressible_debug_section(const char* secname
)
499 return (is_prefix_of(".debug", secname
));
502 // We may see compressed debug sections in input files. Return TRUE
503 // if this is the name of a compressed debug section.
506 is_compressed_debug_section(const char* secname
)
508 return (is_prefix_of(".zdebug", secname
));
511 // Whether to include this section in the link.
513 template<int size
, bool big_endian
>
515 Layout::include_section(Sized_relobj_file
<size
, big_endian
>*, const char* name
,
516 const elfcpp::Shdr
<size
, big_endian
>& shdr
)
518 if (shdr
.get_sh_flags() & elfcpp::SHF_EXCLUDE
)
521 switch (shdr
.get_sh_type())
523 case elfcpp::SHT_NULL
:
524 case elfcpp::SHT_SYMTAB
:
525 case elfcpp::SHT_DYNSYM
:
526 case elfcpp::SHT_HASH
:
527 case elfcpp::SHT_DYNAMIC
:
528 case elfcpp::SHT_SYMTAB_SHNDX
:
531 case elfcpp::SHT_STRTAB
:
532 // Discard the sections which have special meanings in the ELF
533 // ABI. Keep others (e.g., .stabstr). We could also do this by
534 // checking the sh_link fields of the appropriate sections.
535 return (strcmp(name
, ".dynstr") != 0
536 && strcmp(name
, ".strtab") != 0
537 && strcmp(name
, ".shstrtab") != 0);
539 case elfcpp::SHT_RELA
:
540 case elfcpp::SHT_REL
:
541 case elfcpp::SHT_GROUP
:
542 // If we are emitting relocations these should be handled
544 gold_assert(!parameters
->options().relocatable()
545 && !parameters
->options().emit_relocs());
548 case elfcpp::SHT_PROGBITS
:
549 if (parameters
->options().strip_debug()
550 && (shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) == 0)
552 if (is_debug_info_section(name
))
555 if (parameters
->options().strip_debug_non_line()
556 && (shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) == 0)
558 // Debugging sections can only be recognized by name.
559 if (is_prefix_of(".debug", name
)
560 && !is_lines_only_debug_section(name
))
563 if (parameters
->options().strip_debug_gdb()
564 && (shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) == 0)
566 // Debugging sections can only be recognized by name.
567 if (is_prefix_of(".debug", name
)
568 && !is_gdb_debug_section(name
))
571 if (parameters
->options().strip_lto_sections()
572 && !parameters
->options().relocatable()
573 && (shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) == 0)
575 // Ignore LTO sections containing intermediate code.
576 if (is_prefix_of(".gnu.lto_", name
))
579 // The GNU linker strips .gnu_debuglink sections, so we do too.
580 // This is a feature used to keep debugging information in
582 if (strcmp(name
, ".gnu_debuglink") == 0)
591 // Return an output section named NAME, or NULL if there is none.
594 Layout::find_output_section(const char* name
) const
596 for (Section_list::const_iterator p
= this->section_list_
.begin();
597 p
!= this->section_list_
.end();
599 if (strcmp((*p
)->name(), name
) == 0)
604 // Return an output segment of type TYPE, with segment flags SET set
605 // and segment flags CLEAR clear. Return NULL if there is none.
608 Layout::find_output_segment(elfcpp::PT type
, elfcpp::Elf_Word set
,
609 elfcpp::Elf_Word clear
) const
611 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
612 p
!= this->segment_list_
.end();
614 if (static_cast<elfcpp::PT
>((*p
)->type()) == type
615 && ((*p
)->flags() & set
) == set
616 && ((*p
)->flags() & clear
) == 0)
621 // When we put a .ctors or .dtors section with more than one word into
622 // a .init_array or .fini_array section, we need to reverse the words
623 // in the .ctors/.dtors section. This is because .init_array executes
624 // constructors front to back, where .ctors executes them back to
625 // front, and vice-versa for .fini_array/.dtors. Although we do want
626 // to remap .ctors/.dtors into .init_array/.fini_array because it can
627 // be more efficient, we don't want to change the order in which
628 // constructors/destructors are run. This set just keeps track of
629 // these sections which need to be reversed. It is only changed by
630 // Layout::layout. It should be a private member of Layout, but that
631 // would require layout.h to #include object.h to get the definition
633 static Unordered_set
<Section_id
, Section_id_hash
> ctors_sections_in_init_array
;
635 // Return whether OBJECT/SHNDX is a .ctors/.dtors section mapped to a
636 // .init_array/.fini_array section.
639 Layout::is_ctors_in_init_array(Relobj
* relobj
, unsigned int shndx
) const
641 return (ctors_sections_in_init_array
.find(Section_id(relobj
, shndx
))
642 != ctors_sections_in_init_array
.end());
645 // Return the output section to use for section NAME with type TYPE
646 // and section flags FLAGS. NAME must be canonicalized in the string
647 // pool, and NAME_KEY is the key. ORDER is where this should appear
648 // in the output sections. IS_RELRO is true for a relro section.
651 Layout::get_output_section(const char* name
, Stringpool::Key name_key
,
652 elfcpp::Elf_Word type
, elfcpp::Elf_Xword flags
,
653 Output_section_order order
, bool is_relro
)
655 elfcpp::Elf_Word lookup_type
= type
;
657 // For lookup purposes, treat INIT_ARRAY, FINI_ARRAY, and
658 // PREINIT_ARRAY like PROGBITS. This ensures that we combine
659 // .init_array, .fini_array, and .preinit_array sections by name
660 // whatever their type in the input file. We do this because the
661 // types are not always right in the input files.
662 if (lookup_type
== elfcpp::SHT_INIT_ARRAY
663 || lookup_type
== elfcpp::SHT_FINI_ARRAY
664 || lookup_type
== elfcpp::SHT_PREINIT_ARRAY
)
665 lookup_type
= elfcpp::SHT_PROGBITS
;
667 elfcpp::Elf_Xword lookup_flags
= flags
;
669 // Ignoring SHF_WRITE and SHF_EXECINSTR here means that we combine
670 // read-write with read-only sections. Some other ELF linkers do
671 // not do this. FIXME: Perhaps there should be an option
673 lookup_flags
&= ~(elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
);
675 const Key
key(name_key
, std::make_pair(lookup_type
, lookup_flags
));
676 const std::pair
<Key
, Output_section
*> v(key
, NULL
);
677 std::pair
<Section_name_map::iterator
, bool> ins(
678 this->section_name_map_
.insert(v
));
681 return ins
.first
->second
;
684 // This is the first time we've seen this name/type/flags
685 // combination. For compatibility with the GNU linker, we
686 // combine sections with contents and zero flags with sections
687 // with non-zero flags. This is a workaround for cases where
688 // assembler code forgets to set section flags. FIXME: Perhaps
689 // there should be an option to control this.
690 Output_section
* os
= NULL
;
692 if (lookup_type
== elfcpp::SHT_PROGBITS
)
696 Output_section
* same_name
= this->find_output_section(name
);
697 if (same_name
!= NULL
698 && (same_name
->type() == elfcpp::SHT_PROGBITS
699 || same_name
->type() == elfcpp::SHT_INIT_ARRAY
700 || same_name
->type() == elfcpp::SHT_FINI_ARRAY
701 || same_name
->type() == elfcpp::SHT_PREINIT_ARRAY
)
702 && (same_name
->flags() & elfcpp::SHF_TLS
) == 0)
705 else if ((flags
& elfcpp::SHF_TLS
) == 0)
707 elfcpp::Elf_Xword zero_flags
= 0;
708 const Key
zero_key(name_key
, std::make_pair(lookup_type
,
710 Section_name_map::iterator p
=
711 this->section_name_map_
.find(zero_key
);
712 if (p
!= this->section_name_map_
.end())
718 os
= this->make_output_section(name
, type
, flags
, order
, is_relro
);
720 ins
.first
->second
= os
;
725 // Pick the output section to use for section NAME, in input file
726 // RELOBJ, with type TYPE and flags FLAGS. RELOBJ may be NULL for a
727 // linker created section. IS_INPUT_SECTION is true if we are
728 // choosing an output section for an input section found in a input
729 // file. ORDER is where this section should appear in the output
730 // sections. IS_RELRO is true for a relro section. This will return
731 // NULL if the input section should be discarded.
734 Layout::choose_output_section(const Relobj
* relobj
, const char* name
,
735 elfcpp::Elf_Word type
, elfcpp::Elf_Xword flags
,
736 bool is_input_section
, Output_section_order order
,
739 // We should not see any input sections after we have attached
740 // sections to segments.
741 gold_assert(!is_input_section
|| !this->sections_are_attached_
);
743 // Some flags in the input section should not be automatically
744 // copied to the output section.
745 flags
&= ~ (elfcpp::SHF_INFO_LINK
748 | elfcpp::SHF_STRINGS
);
750 // We only clear the SHF_LINK_ORDER flag in for
751 // a non-relocatable link.
752 if (!parameters
->options().relocatable())
753 flags
&= ~elfcpp::SHF_LINK_ORDER
;
755 if (this->script_options_
->saw_sections_clause())
757 // We are using a SECTIONS clause, so the output section is
758 // chosen based only on the name.
760 Script_sections
* ss
= this->script_options_
->script_sections();
761 const char* file_name
= relobj
== NULL
? NULL
: relobj
->name().c_str();
762 Output_section
** output_section_slot
;
763 Script_sections::Section_type script_section_type
;
764 const char* orig_name
= name
;
765 name
= ss
->output_section_name(file_name
, name
, &output_section_slot
,
766 &script_section_type
);
769 gold_debug(DEBUG_SCRIPT
, _("Unable to create output section '%s' "
770 "because it is not allowed by the "
771 "SECTIONS clause of the linker script"),
773 // The SECTIONS clause says to discard this input section.
777 // We can only handle script section types ST_NONE and ST_NOLOAD.
778 switch (script_section_type
)
780 case Script_sections::ST_NONE
:
782 case Script_sections::ST_NOLOAD
:
783 flags
&= elfcpp::SHF_ALLOC
;
789 // If this is an orphan section--one not mentioned in the linker
790 // script--then OUTPUT_SECTION_SLOT will be NULL, and we do the
791 // default processing below.
793 if (output_section_slot
!= NULL
)
795 if (*output_section_slot
!= NULL
)
797 (*output_section_slot
)->update_flags_for_input_section(flags
);
798 return *output_section_slot
;
801 // We don't put sections found in the linker script into
802 // SECTION_NAME_MAP_. That keeps us from getting confused
803 // if an orphan section is mapped to a section with the same
804 // name as one in the linker script.
806 name
= this->namepool_
.add(name
, false, NULL
);
808 Output_section
* os
= this->make_output_section(name
, type
, flags
,
811 os
->set_found_in_sections_clause();
813 // Special handling for NOLOAD sections.
814 if (script_section_type
== Script_sections::ST_NOLOAD
)
818 // The constructor of Output_section sets addresses of non-ALLOC
819 // sections to 0 by default. We don't want that for NOLOAD
820 // sections even if they have no SHF_ALLOC flag.
821 if ((os
->flags() & elfcpp::SHF_ALLOC
) == 0
822 && os
->is_address_valid())
824 gold_assert(os
->address() == 0
825 && !os
->is_offset_valid()
826 && !os
->is_data_size_valid());
827 os
->reset_address_and_file_offset();
831 *output_section_slot
= os
;
836 // FIXME: Handle SHF_OS_NONCONFORMING somewhere.
838 size_t len
= strlen(name
);
839 char* uncompressed_name
= NULL
;
841 // Compressed debug sections should be mapped to the corresponding
842 // uncompressed section.
843 if (is_compressed_debug_section(name
))
845 uncompressed_name
= new char[len
];
846 uncompressed_name
[0] = '.';
847 gold_assert(name
[0] == '.' && name
[1] == 'z');
848 strncpy(&uncompressed_name
[1], &name
[2], len
- 2);
849 uncompressed_name
[len
- 1] = '\0';
851 name
= uncompressed_name
;
854 // Turn NAME from the name of the input section into the name of the
857 && !this->script_options_
->saw_sections_clause()
858 && !parameters
->options().relocatable())
859 name
= Layout::output_section_name(relobj
, name
, &len
);
861 Stringpool::Key name_key
;
862 name
= this->namepool_
.add_with_length(name
, len
, true, &name_key
);
864 if (uncompressed_name
!= NULL
)
865 delete[] uncompressed_name
;
867 // Find or make the output section. The output section is selected
868 // based on the section name, type, and flags.
869 return this->get_output_section(name
, name_key
, type
, flags
, order
, is_relro
);
872 // For incremental links, record the initial fixed layout of a section
873 // from the base file, and return a pointer to the Output_section.
875 template<int size
, bool big_endian
>
877 Layout::init_fixed_output_section(const char* name
,
878 elfcpp::Shdr
<size
, big_endian
>& shdr
)
880 unsigned int sh_type
= shdr
.get_sh_type();
882 // We preserve the layout of PROGBITS, NOBITS, and NOTE sections.
883 // All others will be created from scratch and reallocated.
884 if (sh_type
!= elfcpp::SHT_PROGBITS
885 && sh_type
!= elfcpp::SHT_NOBITS
886 && sh_type
!= elfcpp::SHT_NOTE
)
889 typename
elfcpp::Elf_types
<size
>::Elf_Addr sh_addr
= shdr
.get_sh_addr();
890 typename
elfcpp::Elf_types
<size
>::Elf_Off sh_offset
= shdr
.get_sh_offset();
891 typename
elfcpp::Elf_types
<size
>::Elf_WXword sh_size
= shdr
.get_sh_size();
892 typename
elfcpp::Elf_types
<size
>::Elf_WXword sh_flags
= shdr
.get_sh_flags();
893 typename
elfcpp::Elf_types
<size
>::Elf_WXword sh_addralign
=
894 shdr
.get_sh_addralign();
896 // Make the output section.
897 Stringpool::Key name_key
;
898 name
= this->namepool_
.add(name
, true, &name_key
);
899 Output_section
* os
= this->get_output_section(name
, name_key
, sh_type
,
900 sh_flags
, ORDER_INVALID
, false);
901 os
->set_fixed_layout(sh_addr
, sh_offset
, sh_size
, sh_addralign
);
902 if (sh_type
!= elfcpp::SHT_NOBITS
)
903 this->free_list_
.remove(sh_offset
, sh_offset
+ sh_size
);
907 // Return the output section to use for input section SHNDX, with name
908 // NAME, with header HEADER, from object OBJECT. RELOC_SHNDX is the
909 // index of a relocation section which applies to this section, or 0
910 // if none, or -1U if more than one. RELOC_TYPE is the type of the
911 // relocation section if there is one. Set *OFF to the offset of this
912 // input section without the output section. Return NULL if the
913 // section should be discarded. Set *OFF to -1 if the section
914 // contents should not be written directly to the output file, but
915 // will instead receive special handling.
917 template<int size
, bool big_endian
>
919 Layout::layout(Sized_relobj_file
<size
, big_endian
>* object
, unsigned int shndx
,
920 const char* name
, const elfcpp::Shdr
<size
, big_endian
>& shdr
,
921 unsigned int reloc_shndx
, unsigned int, off_t
* off
)
925 if (!this->include_section(object
, name
, shdr
))
928 elfcpp::Elf_Word sh_type
= shdr
.get_sh_type();
930 // In a relocatable link a grouped section must not be combined with
931 // any other sections.
933 if (parameters
->options().relocatable()
934 && (shdr
.get_sh_flags() & elfcpp::SHF_GROUP
) != 0)
936 name
= this->namepool_
.add(name
, true, NULL
);
937 os
= this->make_output_section(name
, sh_type
, shdr
.get_sh_flags(),
938 ORDER_INVALID
, false);
942 os
= this->choose_output_section(object
, name
, sh_type
,
943 shdr
.get_sh_flags(), true,
944 ORDER_INVALID
, false);
949 // By default the GNU linker sorts input sections whose names match
950 // .ctors.*, .dtors.*, .init_array.*, or .fini_array.*. The
951 // sections are sorted by name. This is used to implement
952 // constructor priority ordering. We are compatible. When we put
953 // .ctor sections in .init_array and .dtor sections in .fini_array,
954 // we must also sort plain .ctor and .dtor sections.
955 if (!this->script_options_
->saw_sections_clause()
956 && !parameters
->options().relocatable()
957 && (is_prefix_of(".ctors.", name
)
958 || is_prefix_of(".dtors.", name
)
959 || is_prefix_of(".init_array.", name
)
960 || is_prefix_of(".fini_array.", name
)
961 || (parameters
->options().ctors_in_init_array()
962 && (strcmp(name
, ".ctors") == 0
963 || strcmp(name
, ".dtors") == 0))))
964 os
->set_must_sort_attached_input_sections();
966 // If this is a .ctors or .ctors.* section being mapped to a
967 // .init_array section, or a .dtors or .dtors.* section being mapped
968 // to a .fini_array section, we will need to reverse the words if
969 // there is more than one. Record this section for later. See
970 // ctors_sections_in_init_array above.
971 if (!this->script_options_
->saw_sections_clause()
972 && !parameters
->options().relocatable()
973 && shdr
.get_sh_size() > size
/ 8
974 && (((strcmp(name
, ".ctors") == 0
975 || is_prefix_of(".ctors.", name
))
976 && strcmp(os
->name(), ".init_array") == 0)
977 || ((strcmp(name
, ".dtors") == 0
978 || is_prefix_of(".dtors.", name
))
979 && strcmp(os
->name(), ".fini_array") == 0)))
980 ctors_sections_in_init_array
.insert(Section_id(object
, shndx
));
982 // FIXME: Handle SHF_LINK_ORDER somewhere.
984 elfcpp::Elf_Xword orig_flags
= os
->flags();
986 *off
= os
->add_input_section(this, object
, shndx
, name
, shdr
, reloc_shndx
,
987 this->script_options_
->saw_sections_clause());
989 // If the flags changed, we may have to change the order.
990 if ((orig_flags
& elfcpp::SHF_ALLOC
) != 0)
992 orig_flags
&= (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
);
993 elfcpp::Elf_Xword new_flags
=
994 os
->flags() & (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
);
995 if (orig_flags
!= new_flags
)
996 os
->set_order(this->default_section_order(os
, false));
999 this->have_added_input_section_
= true;
1004 // Handle a relocation section when doing a relocatable link.
1006 template<int size
, bool big_endian
>
1008 Layout::layout_reloc(Sized_relobj_file
<size
, big_endian
>* object
,
1010 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
1011 Output_section
* data_section
,
1012 Relocatable_relocs
* rr
)
1014 gold_assert(parameters
->options().relocatable()
1015 || parameters
->options().emit_relocs());
1017 int sh_type
= shdr
.get_sh_type();
1020 if (sh_type
== elfcpp::SHT_REL
)
1022 else if (sh_type
== elfcpp::SHT_RELA
)
1026 name
+= data_section
->name();
1028 // In a relocatable link relocs for a grouped section must not be
1029 // combined with other reloc sections.
1031 if (!parameters
->options().relocatable()
1032 || (data_section
->flags() & elfcpp::SHF_GROUP
) == 0)
1033 os
= this->choose_output_section(object
, name
.c_str(), sh_type
,
1034 shdr
.get_sh_flags(), false,
1035 ORDER_INVALID
, false);
1038 const char* n
= this->namepool_
.add(name
.c_str(), true, NULL
);
1039 os
= this->make_output_section(n
, sh_type
, shdr
.get_sh_flags(),
1040 ORDER_INVALID
, false);
1043 os
->set_should_link_to_symtab();
1044 os
->set_info_section(data_section
);
1046 Output_section_data
* posd
;
1047 if (sh_type
== elfcpp::SHT_REL
)
1049 os
->set_entsize(elfcpp::Elf_sizes
<size
>::rel_size
);
1050 posd
= new Output_relocatable_relocs
<elfcpp::SHT_REL
,
1054 else if (sh_type
== elfcpp::SHT_RELA
)
1056 os
->set_entsize(elfcpp::Elf_sizes
<size
>::rela_size
);
1057 posd
= new Output_relocatable_relocs
<elfcpp::SHT_RELA
,
1064 os
->add_output_section_data(posd
);
1065 rr
->set_output_data(posd
);
1070 // Handle a group section when doing a relocatable link.
1072 template<int size
, bool big_endian
>
1074 Layout::layout_group(Symbol_table
* symtab
,
1075 Sized_relobj_file
<size
, big_endian
>* object
,
1077 const char* group_section_name
,
1078 const char* signature
,
1079 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
1080 elfcpp::Elf_Word flags
,
1081 std::vector
<unsigned int>* shndxes
)
1083 gold_assert(parameters
->options().relocatable());
1084 gold_assert(shdr
.get_sh_type() == elfcpp::SHT_GROUP
);
1085 group_section_name
= this->namepool_
.add(group_section_name
, true, NULL
);
1086 Output_section
* os
= this->make_output_section(group_section_name
,
1088 shdr
.get_sh_flags(),
1089 ORDER_INVALID
, false);
1091 // We need to find a symbol with the signature in the symbol table.
1092 // If we don't find one now, we need to look again later.
1093 Symbol
* sym
= symtab
->lookup(signature
, NULL
);
1095 os
->set_info_symndx(sym
);
1098 // Reserve some space to minimize reallocations.
1099 if (this->group_signatures_
.empty())
1100 this->group_signatures_
.reserve(this->number_of_input_files_
* 16);
1102 // We will wind up using a symbol whose name is the signature.
1103 // So just put the signature in the symbol name pool to save it.
1104 signature
= symtab
->canonicalize_name(signature
);
1105 this->group_signatures_
.push_back(Group_signature(os
, signature
));
1108 os
->set_should_link_to_symtab();
1111 section_size_type entry_count
=
1112 convert_to_section_size_type(shdr
.get_sh_size() / 4);
1113 Output_section_data
* posd
=
1114 new Output_data_group
<size
, big_endian
>(object
, entry_count
, flags
,
1116 os
->add_output_section_data(posd
);
1119 // Special GNU handling of sections name .eh_frame. They will
1120 // normally hold exception frame data as defined by the C++ ABI
1121 // (http://codesourcery.com/cxx-abi/).
1123 template<int size
, bool big_endian
>
1125 Layout::layout_eh_frame(Sized_relobj_file
<size
, big_endian
>* object
,
1126 const unsigned char* symbols
,
1128 const unsigned char* symbol_names
,
1129 off_t symbol_names_size
,
1131 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
1132 unsigned int reloc_shndx
, unsigned int reloc_type
,
1135 gold_assert(shdr
.get_sh_type() == elfcpp::SHT_PROGBITS
);
1136 gold_assert((shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) != 0);
1138 const char* const name
= ".eh_frame";
1139 Output_section
* os
= this->choose_output_section(object
, name
,
1140 elfcpp::SHT_PROGBITS
,
1141 elfcpp::SHF_ALLOC
, false,
1142 ORDER_EHFRAME
, false);
1146 if (this->eh_frame_section_
== NULL
)
1148 this->eh_frame_section_
= os
;
1149 this->eh_frame_data_
= new Eh_frame();
1151 // For incremental linking, we do not optimize .eh_frame sections
1152 // or create a .eh_frame_hdr section.
1153 if (parameters
->options().eh_frame_hdr() && !parameters
->incremental())
1155 Output_section
* hdr_os
=
1156 this->choose_output_section(NULL
, ".eh_frame_hdr",
1157 elfcpp::SHT_PROGBITS
,
1158 elfcpp::SHF_ALLOC
, false,
1159 ORDER_EHFRAME
, false);
1163 Eh_frame_hdr
* hdr_posd
= new Eh_frame_hdr(os
,
1164 this->eh_frame_data_
);
1165 hdr_os
->add_output_section_data(hdr_posd
);
1167 hdr_os
->set_after_input_sections();
1169 if (!this->script_options_
->saw_phdrs_clause())
1171 Output_segment
* hdr_oseg
;
1172 hdr_oseg
= this->make_output_segment(elfcpp::PT_GNU_EH_FRAME
,
1174 hdr_oseg
->add_output_section_to_nonload(hdr_os
,
1178 this->eh_frame_data_
->set_eh_frame_hdr(hdr_posd
);
1183 gold_assert(this->eh_frame_section_
== os
);
1185 elfcpp::Elf_Xword orig_flags
= os
->flags();
1187 if (!parameters
->incremental()
1188 && this->eh_frame_data_
->add_ehframe_input_section(object
,
1197 os
->update_flags_for_input_section(shdr
.get_sh_flags());
1199 // A writable .eh_frame section is a RELRO section.
1200 if ((orig_flags
& (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
))
1201 != (os
->flags() & (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
)))
1204 os
->set_order(ORDER_RELRO
);
1207 // We found a .eh_frame section we are going to optimize, so now
1208 // we can add the set of optimized sections to the output
1209 // section. We need to postpone adding this until we've found a
1210 // section we can optimize so that the .eh_frame section in
1211 // crtbegin.o winds up at the start of the output section.
1212 if (!this->added_eh_frame_data_
)
1214 os
->add_output_section_data(this->eh_frame_data_
);
1215 this->added_eh_frame_data_
= true;
1221 // We couldn't handle this .eh_frame section for some reason.
1222 // Add it as a normal section.
1223 bool saw_sections_clause
= this->script_options_
->saw_sections_clause();
1224 *off
= os
->add_input_section(this, object
, shndx
, name
, shdr
, reloc_shndx
,
1225 saw_sections_clause
);
1226 this->have_added_input_section_
= true;
1228 if ((orig_flags
& (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
))
1229 != (os
->flags() & (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
)))
1230 os
->set_order(this->default_section_order(os
, false));
1236 // Add POSD to an output section using NAME, TYPE, and FLAGS. Return
1237 // the output section.
1240 Layout::add_output_section_data(const char* name
, elfcpp::Elf_Word type
,
1241 elfcpp::Elf_Xword flags
,
1242 Output_section_data
* posd
,
1243 Output_section_order order
, bool is_relro
)
1245 Output_section
* os
= this->choose_output_section(NULL
, name
, type
, flags
,
1246 false, order
, is_relro
);
1248 os
->add_output_section_data(posd
);
1252 // Map section flags to segment flags.
1255 Layout::section_flags_to_segment(elfcpp::Elf_Xword flags
)
1257 elfcpp::Elf_Word ret
= elfcpp::PF_R
;
1258 if ((flags
& elfcpp::SHF_WRITE
) != 0)
1259 ret
|= elfcpp::PF_W
;
1260 if ((flags
& elfcpp::SHF_EXECINSTR
) != 0)
1261 ret
|= elfcpp::PF_X
;
1265 // Make a new Output_section, and attach it to segments as
1266 // appropriate. ORDER is the order in which this section should
1267 // appear in the output segment. IS_RELRO is true if this is a relro
1268 // (read-only after relocations) section.
1271 Layout::make_output_section(const char* name
, elfcpp::Elf_Word type
,
1272 elfcpp::Elf_Xword flags
,
1273 Output_section_order order
, bool is_relro
)
1276 if ((flags
& elfcpp::SHF_ALLOC
) == 0
1277 && strcmp(parameters
->options().compress_debug_sections(), "none") != 0
1278 && is_compressible_debug_section(name
))
1279 os
= new Output_compressed_section(¶meters
->options(), name
, type
,
1281 else if ((flags
& elfcpp::SHF_ALLOC
) == 0
1282 && parameters
->options().strip_debug_non_line()
1283 && strcmp(".debug_abbrev", name
) == 0)
1285 os
= this->debug_abbrev_
= new Output_reduced_debug_abbrev_section(
1287 if (this->debug_info_
)
1288 this->debug_info_
->set_abbreviations(this->debug_abbrev_
);
1290 else if ((flags
& elfcpp::SHF_ALLOC
) == 0
1291 && parameters
->options().strip_debug_non_line()
1292 && strcmp(".debug_info", name
) == 0)
1294 os
= this->debug_info_
= new Output_reduced_debug_info_section(
1296 if (this->debug_abbrev_
)
1297 this->debug_info_
->set_abbreviations(this->debug_abbrev_
);
1301 // Sometimes .init_array*, .preinit_array* and .fini_array* do
1302 // not have correct section types. Force them here.
1303 if (type
== elfcpp::SHT_PROGBITS
)
1305 if (is_prefix_of(".init_array", name
))
1306 type
= elfcpp::SHT_INIT_ARRAY
;
1307 else if (is_prefix_of(".preinit_array", name
))
1308 type
= elfcpp::SHT_PREINIT_ARRAY
;
1309 else if (is_prefix_of(".fini_array", name
))
1310 type
= elfcpp::SHT_FINI_ARRAY
;
1313 // FIXME: const_cast is ugly.
1314 Target
* target
= const_cast<Target
*>(¶meters
->target());
1315 os
= target
->make_output_section(name
, type
, flags
);
1318 // With -z relro, we have to recognize the special sections by name.
1319 // There is no other way.
1320 bool is_relro_local
= false;
1321 if (!this->script_options_
->saw_sections_clause()
1322 && parameters
->options().relro()
1323 && type
== elfcpp::SHT_PROGBITS
1324 && (flags
& elfcpp::SHF_ALLOC
) != 0
1325 && (flags
& elfcpp::SHF_WRITE
) != 0)
1327 if (strcmp(name
, ".data.rel.ro") == 0)
1329 else if (strcmp(name
, ".data.rel.ro.local") == 0)
1332 is_relro_local
= true;
1334 else if (type
== elfcpp::SHT_INIT_ARRAY
1335 || type
== elfcpp::SHT_FINI_ARRAY
1336 || type
== elfcpp::SHT_PREINIT_ARRAY
)
1338 else if (strcmp(name
, ".ctors") == 0
1339 || strcmp(name
, ".dtors") == 0
1340 || strcmp(name
, ".jcr") == 0)
1347 if (order
== ORDER_INVALID
&& (flags
& elfcpp::SHF_ALLOC
) != 0)
1348 order
= this->default_section_order(os
, is_relro_local
);
1350 os
->set_order(order
);
1352 parameters
->target().new_output_section(os
);
1354 this->section_list_
.push_back(os
);
1356 // The GNU linker by default sorts some sections by priority, so we
1357 // do the same. We need to know that this might happen before we
1358 // attach any input sections.
1359 if (!this->script_options_
->saw_sections_clause()
1360 && !parameters
->options().relocatable()
1361 && (strcmp(name
, ".init_array") == 0
1362 || strcmp(name
, ".fini_array") == 0
1363 || (!parameters
->options().ctors_in_init_array()
1364 && (strcmp(name
, ".ctors") == 0
1365 || strcmp(name
, ".dtors") == 0))))
1366 os
->set_may_sort_attached_input_sections();
1368 // Check for .stab*str sections, as .stab* sections need to link to
1370 if (type
== elfcpp::SHT_STRTAB
1371 && !this->have_stabstr_section_
1372 && strncmp(name
, ".stab", 5) == 0
1373 && strcmp(name
+ strlen(name
) - 3, "str") == 0)
1374 this->have_stabstr_section_
= true;
1376 // If we have already attached the sections to segments, then we
1377 // need to attach this one now. This happens for sections created
1378 // directly by the linker.
1379 if (this->sections_are_attached_
)
1380 this->attach_section_to_segment(os
);
1385 // Return the default order in which a section should be placed in an
1386 // output segment. This function captures a lot of the ideas in
1387 // ld/scripttempl/elf.sc in the GNU linker. Note that the order of a
1388 // linker created section is normally set when the section is created;
1389 // this function is used for input sections.
1391 Output_section_order
1392 Layout::default_section_order(Output_section
* os
, bool is_relro_local
)
1394 gold_assert((os
->flags() & elfcpp::SHF_ALLOC
) != 0);
1395 bool is_write
= (os
->flags() & elfcpp::SHF_WRITE
) != 0;
1396 bool is_execinstr
= (os
->flags() & elfcpp::SHF_EXECINSTR
) != 0;
1397 bool is_bss
= false;
1402 case elfcpp::SHT_PROGBITS
:
1404 case elfcpp::SHT_NOBITS
:
1407 case elfcpp::SHT_RELA
:
1408 case elfcpp::SHT_REL
:
1410 return ORDER_DYNAMIC_RELOCS
;
1412 case elfcpp::SHT_HASH
:
1413 case elfcpp::SHT_DYNAMIC
:
1414 case elfcpp::SHT_SHLIB
:
1415 case elfcpp::SHT_DYNSYM
:
1416 case elfcpp::SHT_GNU_HASH
:
1417 case elfcpp::SHT_GNU_verdef
:
1418 case elfcpp::SHT_GNU_verneed
:
1419 case elfcpp::SHT_GNU_versym
:
1421 return ORDER_DYNAMIC_LINKER
;
1423 case elfcpp::SHT_NOTE
:
1424 return is_write
? ORDER_RW_NOTE
: ORDER_RO_NOTE
;
1427 if ((os
->flags() & elfcpp::SHF_TLS
) != 0)
1428 return is_bss
? ORDER_TLS_BSS
: ORDER_TLS_DATA
;
1430 if (!is_bss
&& !is_write
)
1434 if (strcmp(os
->name(), ".init") == 0)
1436 else if (strcmp(os
->name(), ".fini") == 0)
1439 return is_execinstr
? ORDER_TEXT
: ORDER_READONLY
;
1443 return is_relro_local
? ORDER_RELRO_LOCAL
: ORDER_RELRO
;
1445 if (os
->is_small_section())
1446 return is_bss
? ORDER_SMALL_BSS
: ORDER_SMALL_DATA
;
1447 if (os
->is_large_section())
1448 return is_bss
? ORDER_LARGE_BSS
: ORDER_LARGE_DATA
;
1450 return is_bss
? ORDER_BSS
: ORDER_DATA
;
1453 // Attach output sections to segments. This is called after we have
1454 // seen all the input sections.
1457 Layout::attach_sections_to_segments()
1459 for (Section_list::iterator p
= this->section_list_
.begin();
1460 p
!= this->section_list_
.end();
1462 this->attach_section_to_segment(*p
);
1464 this->sections_are_attached_
= true;
1467 // Attach an output section to a segment.
1470 Layout::attach_section_to_segment(Output_section
* os
)
1472 if ((os
->flags() & elfcpp::SHF_ALLOC
) == 0)
1473 this->unattached_section_list_
.push_back(os
);
1475 this->attach_allocated_section_to_segment(os
);
1478 // Attach an allocated output section to a segment.
1481 Layout::attach_allocated_section_to_segment(Output_section
* os
)
1483 elfcpp::Elf_Xword flags
= os
->flags();
1484 gold_assert((flags
& elfcpp::SHF_ALLOC
) != 0);
1486 if (parameters
->options().relocatable())
1489 // If we have a SECTIONS clause, we can't handle the attachment to
1490 // segments until after we've seen all the sections.
1491 if (this->script_options_
->saw_sections_clause())
1494 gold_assert(!this->script_options_
->saw_phdrs_clause());
1496 // This output section goes into a PT_LOAD segment.
1498 elfcpp::Elf_Word seg_flags
= Layout::section_flags_to_segment(flags
);
1500 // Check for --section-start.
1502 bool is_address_set
= parameters
->options().section_start(os
->name(), &addr
);
1504 // In general the only thing we really care about for PT_LOAD
1505 // segments is whether or not they are writable or executable,
1506 // so that is how we search for them.
1507 // Large data sections also go into their own PT_LOAD segment.
1508 // People who need segments sorted on some other basis will
1509 // have to use a linker script.
1511 Segment_list::const_iterator p
;
1512 for (p
= this->segment_list_
.begin();
1513 p
!= this->segment_list_
.end();
1516 if ((*p
)->type() != elfcpp::PT_LOAD
)
1518 if (!parameters
->options().omagic()
1519 && ((*p
)->flags() & elfcpp::PF_W
) != (seg_flags
& elfcpp::PF_W
))
1521 if (parameters
->options().rosegment()
1522 && ((*p
)->flags() & elfcpp::PF_X
) != (seg_flags
& elfcpp::PF_X
))
1524 // If -Tbss was specified, we need to separate the data and BSS
1526 if (parameters
->options().user_set_Tbss())
1528 if ((os
->type() == elfcpp::SHT_NOBITS
)
1529 == (*p
)->has_any_data_sections())
1532 if (os
->is_large_data_section() && !(*p
)->is_large_data_segment())
1537 if ((*p
)->are_addresses_set())
1540 (*p
)->add_initial_output_data(os
);
1541 (*p
)->update_flags_for_output_section(seg_flags
);
1542 (*p
)->set_addresses(addr
, addr
);
1546 (*p
)->add_output_section_to_load(this, os
, seg_flags
);
1550 if (p
== this->segment_list_
.end())
1552 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_LOAD
,
1554 if (os
->is_large_data_section())
1555 oseg
->set_is_large_data_segment();
1556 oseg
->add_output_section_to_load(this, os
, seg_flags
);
1558 oseg
->set_addresses(addr
, addr
);
1561 // If we see a loadable SHT_NOTE section, we create a PT_NOTE
1563 if (os
->type() == elfcpp::SHT_NOTE
)
1565 // See if we already have an equivalent PT_NOTE segment.
1566 for (p
= this->segment_list_
.begin();
1567 p
!= segment_list_
.end();
1570 if ((*p
)->type() == elfcpp::PT_NOTE
1571 && (((*p
)->flags() & elfcpp::PF_W
)
1572 == (seg_flags
& elfcpp::PF_W
)))
1574 (*p
)->add_output_section_to_nonload(os
, seg_flags
);
1579 if (p
== this->segment_list_
.end())
1581 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_NOTE
,
1583 oseg
->add_output_section_to_nonload(os
, seg_flags
);
1587 // If we see a loadable SHF_TLS section, we create a PT_TLS
1588 // segment. There can only be one such segment.
1589 if ((flags
& elfcpp::SHF_TLS
) != 0)
1591 if (this->tls_segment_
== NULL
)
1592 this->make_output_segment(elfcpp::PT_TLS
, seg_flags
);
1593 this->tls_segment_
->add_output_section_to_nonload(os
, seg_flags
);
1596 // If -z relro is in effect, and we see a relro section, we create a
1597 // PT_GNU_RELRO segment. There can only be one such segment.
1598 if (os
->is_relro() && parameters
->options().relro())
1600 gold_assert(seg_flags
== (elfcpp::PF_R
| elfcpp::PF_W
));
1601 if (this->relro_segment_
== NULL
)
1602 this->make_output_segment(elfcpp::PT_GNU_RELRO
, seg_flags
);
1603 this->relro_segment_
->add_output_section_to_nonload(os
, seg_flags
);
1606 // If we see a section named .interp, put it into a PT_INTERP
1607 // segment. This seems broken to me, but this is what GNU ld does,
1608 // and glibc expects it.
1609 if (strcmp(os
->name(), ".interp") == 0
1610 && !this->script_options_
->saw_phdrs_clause())
1612 if (this->interp_segment_
== NULL
)
1613 this->make_output_segment(elfcpp::PT_INTERP
, seg_flags
);
1615 gold_warning(_("multiple '.interp' sections in input files "
1616 "may cause confusing PT_INTERP segment"));
1617 this->interp_segment_
->add_output_section_to_nonload(os
, seg_flags
);
1621 // Make an output section for a script.
1624 Layout::make_output_section_for_script(
1626 Script_sections::Section_type section_type
)
1628 name
= this->namepool_
.add(name
, false, NULL
);
1629 elfcpp::Elf_Xword sh_flags
= elfcpp::SHF_ALLOC
;
1630 if (section_type
== Script_sections::ST_NOLOAD
)
1632 Output_section
* os
= this->make_output_section(name
, elfcpp::SHT_PROGBITS
,
1633 sh_flags
, ORDER_INVALID
,
1635 os
->set_found_in_sections_clause();
1636 if (section_type
== Script_sections::ST_NOLOAD
)
1637 os
->set_is_noload();
1641 // Return the number of segments we expect to see.
1644 Layout::expected_segment_count() const
1646 size_t ret
= this->segment_list_
.size();
1648 // If we didn't see a SECTIONS clause in a linker script, we should
1649 // already have the complete list of segments. Otherwise we ask the
1650 // SECTIONS clause how many segments it expects, and add in the ones
1651 // we already have (PT_GNU_STACK, PT_GNU_EH_FRAME, etc.)
1653 if (!this->script_options_
->saw_sections_clause())
1657 const Script_sections
* ss
= this->script_options_
->script_sections();
1658 return ret
+ ss
->expected_segment_count(this);
1662 // Handle the .note.GNU-stack section at layout time. SEEN_GNU_STACK
1663 // is whether we saw a .note.GNU-stack section in the object file.
1664 // GNU_STACK_FLAGS is the section flags. The flags give the
1665 // protection required for stack memory. We record this in an
1666 // executable as a PT_GNU_STACK segment. If an object file does not
1667 // have a .note.GNU-stack segment, we must assume that it is an old
1668 // object. On some targets that will force an executable stack.
1671 Layout::layout_gnu_stack(bool seen_gnu_stack
, uint64_t gnu_stack_flags
,
1674 if (!seen_gnu_stack
)
1676 this->input_without_gnu_stack_note_
= true;
1677 if (parameters
->options().warn_execstack()
1678 && parameters
->target().is_default_stack_executable())
1679 gold_warning(_("%s: missing .note.GNU-stack section"
1680 " implies executable stack"),
1681 obj
->name().c_str());
1685 this->input_with_gnu_stack_note_
= true;
1686 if ((gnu_stack_flags
& elfcpp::SHF_EXECINSTR
) != 0)
1688 this->input_requires_executable_stack_
= true;
1689 if (parameters
->options().warn_execstack()
1690 || parameters
->options().is_stack_executable())
1691 gold_warning(_("%s: requires executable stack"),
1692 obj
->name().c_str());
1697 // Create automatic note sections.
1700 Layout::create_notes()
1702 this->create_gold_note();
1703 this->create_executable_stack_info();
1704 this->create_build_id();
1707 // Create the dynamic sections which are needed before we read the
1711 Layout::create_initial_dynamic_sections(Symbol_table
* symtab
)
1713 if (parameters
->doing_static_link())
1716 this->dynamic_section_
= this->choose_output_section(NULL
, ".dynamic",
1717 elfcpp::SHT_DYNAMIC
,
1719 | elfcpp::SHF_WRITE
),
1723 this->dynamic_symbol_
=
1724 symtab
->define_in_output_data("_DYNAMIC", NULL
, Symbol_table::PREDEFINED
,
1725 this->dynamic_section_
, 0, 0,
1726 elfcpp::STT_OBJECT
, elfcpp::STB_LOCAL
,
1727 elfcpp::STV_HIDDEN
, 0, false, false);
1729 this->dynamic_data_
= new Output_data_dynamic(&this->dynpool_
);
1731 this->dynamic_section_
->add_output_section_data(this->dynamic_data_
);
1734 // For each output section whose name can be represented as C symbol,
1735 // define __start and __stop symbols for the section. This is a GNU
1739 Layout::define_section_symbols(Symbol_table
* symtab
)
1741 for (Section_list::const_iterator p
= this->section_list_
.begin();
1742 p
!= this->section_list_
.end();
1745 const char* const name
= (*p
)->name();
1746 if (is_cident(name
))
1748 const std::string
name_string(name
);
1749 const std::string
start_name(cident_section_start_prefix
1751 const std::string
stop_name(cident_section_stop_prefix
1754 symtab
->define_in_output_data(start_name
.c_str(),
1756 Symbol_table::PREDEFINED
,
1762 elfcpp::STV_DEFAULT
,
1764 false, // offset_is_from_end
1765 true); // only_if_ref
1767 symtab
->define_in_output_data(stop_name
.c_str(),
1769 Symbol_table::PREDEFINED
,
1775 elfcpp::STV_DEFAULT
,
1777 true, // offset_is_from_end
1778 true); // only_if_ref
1783 // Define symbols for group signatures.
1786 Layout::define_group_signatures(Symbol_table
* symtab
)
1788 for (Group_signatures::iterator p
= this->group_signatures_
.begin();
1789 p
!= this->group_signatures_
.end();
1792 Symbol
* sym
= symtab
->lookup(p
->signature
, NULL
);
1794 p
->section
->set_info_symndx(sym
);
1797 // Force the name of the group section to the group
1798 // signature, and use the group's section symbol as the
1799 // signature symbol.
1800 if (strcmp(p
->section
->name(), p
->signature
) != 0)
1802 const char* name
= this->namepool_
.add(p
->signature
,
1804 p
->section
->set_name(name
);
1806 p
->section
->set_needs_symtab_index();
1807 p
->section
->set_info_section_symndx(p
->section
);
1811 this->group_signatures_
.clear();
1814 // Find the first read-only PT_LOAD segment, creating one if
1818 Layout::find_first_load_seg()
1820 Output_segment
* best
= NULL
;
1821 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
1822 p
!= this->segment_list_
.end();
1825 if ((*p
)->type() == elfcpp::PT_LOAD
1826 && ((*p
)->flags() & elfcpp::PF_R
) != 0
1827 && (parameters
->options().omagic()
1828 || ((*p
)->flags() & elfcpp::PF_W
) == 0))
1830 if (best
== NULL
|| this->segment_precedes(*p
, best
))
1837 gold_assert(!this->script_options_
->saw_phdrs_clause());
1839 Output_segment
* load_seg
= this->make_output_segment(elfcpp::PT_LOAD
,
1844 // Save states of all current output segments. Store saved states
1845 // in SEGMENT_STATES.
1848 Layout::save_segments(Segment_states
* segment_states
)
1850 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
1851 p
!= this->segment_list_
.end();
1854 Output_segment
* segment
= *p
;
1856 Output_segment
* copy
= new Output_segment(*segment
);
1857 (*segment_states
)[segment
] = copy
;
1861 // Restore states of output segments and delete any segment not found in
1865 Layout::restore_segments(const Segment_states
* segment_states
)
1867 // Go through the segment list and remove any segment added in the
1869 this->tls_segment_
= NULL
;
1870 this->relro_segment_
= NULL
;
1871 Segment_list::iterator list_iter
= this->segment_list_
.begin();
1872 while (list_iter
!= this->segment_list_
.end())
1874 Output_segment
* segment
= *list_iter
;
1875 Segment_states::const_iterator states_iter
=
1876 segment_states
->find(segment
);
1877 if (states_iter
!= segment_states
->end())
1879 const Output_segment
* copy
= states_iter
->second
;
1880 // Shallow copy to restore states.
1883 // Also fix up TLS and RELRO segment pointers as appropriate.
1884 if (segment
->type() == elfcpp::PT_TLS
)
1885 this->tls_segment_
= segment
;
1886 else if (segment
->type() == elfcpp::PT_GNU_RELRO
)
1887 this->relro_segment_
= segment
;
1893 list_iter
= this->segment_list_
.erase(list_iter
);
1894 // This is a segment created during section layout. It should be
1895 // safe to remove it since we should have removed all pointers to it.
1901 // Clean up after relaxation so that sections can be laid out again.
1904 Layout::clean_up_after_relaxation()
1906 // Restore the segments to point state just prior to the relaxation loop.
1907 Script_sections
* script_section
= this->script_options_
->script_sections();
1908 script_section
->release_segments();
1909 this->restore_segments(this->segment_states_
);
1911 // Reset section addresses and file offsets
1912 for (Section_list::iterator p
= this->section_list_
.begin();
1913 p
!= this->section_list_
.end();
1916 (*p
)->restore_states();
1918 // If an input section changes size because of relaxation,
1919 // we need to adjust the section offsets of all input sections.
1920 // after such a section.
1921 if ((*p
)->section_offsets_need_adjustment())
1922 (*p
)->adjust_section_offsets();
1924 (*p
)->reset_address_and_file_offset();
1927 // Reset special output object address and file offsets.
1928 for (Data_list::iterator p
= this->special_output_list_
.begin();
1929 p
!= this->special_output_list_
.end();
1931 (*p
)->reset_address_and_file_offset();
1933 // A linker script may have created some output section data objects.
1934 // They are useless now.
1935 for (Output_section_data_list::const_iterator p
=
1936 this->script_output_section_data_list_
.begin();
1937 p
!= this->script_output_section_data_list_
.end();
1940 this->script_output_section_data_list_
.clear();
1943 // Prepare for relaxation.
1946 Layout::prepare_for_relaxation()
1948 // Create an relaxation debug check if in debugging mode.
1949 if (is_debugging_enabled(DEBUG_RELAXATION
))
1950 this->relaxation_debug_check_
= new Relaxation_debug_check();
1952 // Save segment states.
1953 this->segment_states_
= new Segment_states();
1954 this->save_segments(this->segment_states_
);
1956 for(Section_list::const_iterator p
= this->section_list_
.begin();
1957 p
!= this->section_list_
.end();
1959 (*p
)->save_states();
1961 if (is_debugging_enabled(DEBUG_RELAXATION
))
1962 this->relaxation_debug_check_
->check_output_data_for_reset_values(
1963 this->section_list_
, this->special_output_list_
);
1965 // Also enable recording of output section data from scripts.
1966 this->record_output_section_data_from_script_
= true;
1969 // Relaxation loop body: If target has no relaxation, this runs only once
1970 // Otherwise, the target relaxation hook is called at the end of
1971 // each iteration. If the hook returns true, it means re-layout of
1972 // section is required.
1974 // The number of segments created by a linking script without a PHDRS
1975 // clause may be affected by section sizes and alignments. There is
1976 // a remote chance that relaxation causes different number of PT_LOAD
1977 // segments are created and sections are attached to different segments.
1978 // Therefore, we always throw away all segments created during section
1979 // layout. In order to be able to restart the section layout, we keep
1980 // a copy of the segment list right before the relaxation loop and use
1981 // that to restore the segments.
1983 // PASS is the current relaxation pass number.
1984 // SYMTAB is a symbol table.
1985 // PLOAD_SEG is the address of a pointer for the load segment.
1986 // PHDR_SEG is a pointer to the PHDR segment.
1987 // SEGMENT_HEADERS points to the output segment header.
1988 // FILE_HEADER points to the output file header.
1989 // PSHNDX is the address to store the output section index.
1992 Layout::relaxation_loop_body(
1995 Symbol_table
* symtab
,
1996 Output_segment
** pload_seg
,
1997 Output_segment
* phdr_seg
,
1998 Output_segment_headers
* segment_headers
,
1999 Output_file_header
* file_header
,
2000 unsigned int* pshndx
)
2002 // If this is not the first iteration, we need to clean up after
2003 // relaxation so that we can lay out the sections again.
2005 this->clean_up_after_relaxation();
2007 // If there is a SECTIONS clause, put all the input sections into
2008 // the required order.
2009 Output_segment
* load_seg
;
2010 if (this->script_options_
->saw_sections_clause())
2011 load_seg
= this->set_section_addresses_from_script(symtab
);
2012 else if (parameters
->options().relocatable())
2015 load_seg
= this->find_first_load_seg();
2017 if (parameters
->options().oformat_enum()
2018 != General_options::OBJECT_FORMAT_ELF
)
2021 // If the user set the address of the text segment, that may not be
2022 // compatible with putting the segment headers and file headers into
2024 if (parameters
->options().user_set_Ttext())
2027 gold_assert(phdr_seg
== NULL
2029 || this->script_options_
->saw_sections_clause());
2031 // If the address of the load segment we found has been set by
2032 // --section-start rather than by a script, then adjust the VMA and
2033 // LMA downward if possible to include the file and section headers.
2034 uint64_t header_gap
= 0;
2035 if (load_seg
!= NULL
2036 && load_seg
->are_addresses_set()
2037 && !this->script_options_
->saw_sections_clause()
2038 && !parameters
->options().relocatable())
2040 file_header
->finalize_data_size();
2041 segment_headers
->finalize_data_size();
2042 size_t sizeof_headers
= (file_header
->data_size()
2043 + segment_headers
->data_size());
2044 const uint64_t abi_pagesize
= target
->abi_pagesize();
2045 uint64_t hdr_paddr
= load_seg
->paddr() - sizeof_headers
;
2046 hdr_paddr
&= ~(abi_pagesize
- 1);
2047 uint64_t subtract
= load_seg
->paddr() - hdr_paddr
;
2048 if (load_seg
->paddr() < subtract
|| load_seg
->vaddr() < subtract
)
2052 load_seg
->set_addresses(load_seg
->vaddr() - subtract
,
2053 load_seg
->paddr() - subtract
);
2054 header_gap
= subtract
- sizeof_headers
;
2058 // Lay out the segment headers.
2059 if (!parameters
->options().relocatable())
2061 gold_assert(segment_headers
!= NULL
);
2062 if (header_gap
!= 0 && load_seg
!= NULL
)
2064 Output_data_zero_fill
* z
= new Output_data_zero_fill(header_gap
, 1);
2065 load_seg
->add_initial_output_data(z
);
2067 if (load_seg
!= NULL
)
2068 load_seg
->add_initial_output_data(segment_headers
);
2069 if (phdr_seg
!= NULL
)
2070 phdr_seg
->add_initial_output_data(segment_headers
);
2073 // Lay out the file header.
2074 if (load_seg
!= NULL
)
2075 load_seg
->add_initial_output_data(file_header
);
2077 if (this->script_options_
->saw_phdrs_clause()
2078 && !parameters
->options().relocatable())
2080 // Support use of FILEHDRS and PHDRS attachments in a PHDRS
2081 // clause in a linker script.
2082 Script_sections
* ss
= this->script_options_
->script_sections();
2083 ss
->put_headers_in_phdrs(file_header
, segment_headers
);
2086 // We set the output section indexes in set_segment_offsets and
2087 // set_section_indexes.
2090 // Set the file offsets of all the segments, and all the sections
2093 if (!parameters
->options().relocatable())
2094 off
= this->set_segment_offsets(target
, load_seg
, pshndx
);
2096 off
= this->set_relocatable_section_offsets(file_header
, pshndx
);
2098 // Verify that the dummy relaxation does not change anything.
2099 if (is_debugging_enabled(DEBUG_RELAXATION
))
2102 this->relaxation_debug_check_
->read_sections(this->section_list_
);
2104 this->relaxation_debug_check_
->verify_sections(this->section_list_
);
2107 *pload_seg
= load_seg
;
2111 // Search the list of patterns and find the postion of the given section
2112 // name in the output section. If the section name matches a glob
2113 // pattern and a non-glob name, then the non-glob position takes
2114 // precedence. Return 0 if no match is found.
2117 Layout::find_section_order_index(const std::string
& section_name
)
2119 Unordered_map
<std::string
, unsigned int>::iterator map_it
;
2120 map_it
= this->input_section_position_
.find(section_name
);
2121 if (map_it
!= this->input_section_position_
.end())
2122 return map_it
->second
;
2124 // Absolute match failed. Linear search the glob patterns.
2125 std::vector
<std::string
>::iterator it
;
2126 for (it
= this->input_section_glob_
.begin();
2127 it
!= this->input_section_glob_
.end();
2130 if (fnmatch((*it
).c_str(), section_name
.c_str(), FNM_NOESCAPE
) == 0)
2132 map_it
= this->input_section_position_
.find(*it
);
2133 gold_assert(map_it
!= this->input_section_position_
.end());
2134 return map_it
->second
;
2140 // Read the sequence of input sections from the file specified with
2141 // --section-ordering-file.
2144 Layout::read_layout_from_file()
2146 const char* filename
= parameters
->options().section_ordering_file();
2152 gold_fatal(_("unable to open --section-ordering-file file %s: %s"),
2153 filename
, strerror(errno
));
2155 std::getline(in
, line
); // this chops off the trailing \n, if any
2156 unsigned int position
= 1;
2160 if (!line
.empty() && line
[line
.length() - 1] == '\r') // Windows
2161 line
.resize(line
.length() - 1);
2162 // Ignore comments, beginning with '#'
2165 std::getline(in
, line
);
2168 this->input_section_position_
[line
] = position
;
2169 // Store all glob patterns in a vector.
2170 if (is_wildcard_string(line
.c_str()))
2171 this->input_section_glob_
.push_back(line
);
2173 std::getline(in
, line
);
2177 // Finalize the layout. When this is called, we have created all the
2178 // output sections and all the output segments which are based on
2179 // input sections. We have several things to do, and we have to do
2180 // them in the right order, so that we get the right results correctly
2183 // 1) Finalize the list of output segments and create the segment
2186 // 2) Finalize the dynamic symbol table and associated sections.
2188 // 3) Determine the final file offset of all the output segments.
2190 // 4) Determine the final file offset of all the SHF_ALLOC output
2193 // 5) Create the symbol table sections and the section name table
2196 // 6) Finalize the symbol table: set symbol values to their final
2197 // value and make a final determination of which symbols are going
2198 // into the output symbol table.
2200 // 7) Create the section table header.
2202 // 8) Determine the final file offset of all the output sections which
2203 // are not SHF_ALLOC, including the section table header.
2205 // 9) Finalize the ELF file header.
2207 // This function returns the size of the output file.
2210 Layout::finalize(const Input_objects
* input_objects
, Symbol_table
* symtab
,
2211 Target
* target
, const Task
* task
)
2213 target
->finalize_sections(this, input_objects
, symtab
);
2215 this->count_local_symbols(task
, input_objects
);
2217 this->link_stabs_sections();
2219 Output_segment
* phdr_seg
= NULL
;
2220 if (!parameters
->options().relocatable() && !parameters
->doing_static_link())
2222 // There was a dynamic object in the link. We need to create
2223 // some information for the dynamic linker.
2225 // Create the PT_PHDR segment which will hold the program
2227 if (!this->script_options_
->saw_phdrs_clause())
2228 phdr_seg
= this->make_output_segment(elfcpp::PT_PHDR
, elfcpp::PF_R
);
2230 // Create the dynamic symbol table, including the hash table.
2231 Output_section
* dynstr
;
2232 std::vector
<Symbol
*> dynamic_symbols
;
2233 unsigned int local_dynamic_count
;
2234 Versions
versions(*this->script_options()->version_script_info(),
2236 this->create_dynamic_symtab(input_objects
, symtab
, &dynstr
,
2237 &local_dynamic_count
, &dynamic_symbols
,
2240 // Create the .interp section to hold the name of the
2241 // interpreter, and put it in a PT_INTERP segment. Don't do it
2242 // if we saw a .interp section in an input file.
2243 if ((!parameters
->options().shared()
2244 || parameters
->options().dynamic_linker() != NULL
)
2245 && this->interp_segment_
== NULL
)
2246 this->create_interp(target
);
2248 // Finish the .dynamic section to hold the dynamic data, and put
2249 // it in a PT_DYNAMIC segment.
2250 this->finish_dynamic_section(input_objects
, symtab
);
2252 // We should have added everything we need to the dynamic string
2254 this->dynpool_
.set_string_offsets();
2256 // Create the version sections. We can't do this until the
2257 // dynamic string table is complete.
2258 this->create_version_sections(&versions
, symtab
, local_dynamic_count
,
2259 dynamic_symbols
, dynstr
);
2261 // Set the size of the _DYNAMIC symbol. We can't do this until
2262 // after we call create_version_sections.
2263 this->set_dynamic_symbol_size(symtab
);
2266 // Create segment headers.
2267 Output_segment_headers
* segment_headers
=
2268 (parameters
->options().relocatable()
2270 : new Output_segment_headers(this->segment_list_
));
2272 // Lay out the file header.
2273 Output_file_header
* file_header
= new Output_file_header(target
, symtab
,
2276 this->special_output_list_
.push_back(file_header
);
2277 if (segment_headers
!= NULL
)
2278 this->special_output_list_
.push_back(segment_headers
);
2280 // Find approriate places for orphan output sections if we are using
2282 if (this->script_options_
->saw_sections_clause())
2283 this->place_orphan_sections_in_script();
2285 Output_segment
* load_seg
;
2290 // Take a snapshot of the section layout as needed.
2291 if (target
->may_relax())
2292 this->prepare_for_relaxation();
2294 // Run the relaxation loop to lay out sections.
2297 off
= this->relaxation_loop_body(pass
, target
, symtab
, &load_seg
,
2298 phdr_seg
, segment_headers
, file_header
,
2302 while (target
->may_relax()
2303 && target
->relax(pass
, input_objects
, symtab
, this, task
));
2305 // Set the file offsets of all the non-data sections we've seen so
2306 // far which don't have to wait for the input sections. We need
2307 // this in order to finalize local symbols in non-allocated
2309 off
= this->set_section_offsets(off
, BEFORE_INPUT_SECTIONS_PASS
);
2311 // Set the section indexes of all unallocated sections seen so far,
2312 // in case any of them are somehow referenced by a symbol.
2313 shndx
= this->set_section_indexes(shndx
);
2315 // Create the symbol table sections.
2316 this->create_symtab_sections(input_objects
, symtab
, shndx
, &off
);
2317 if (!parameters
->doing_static_link())
2318 this->assign_local_dynsym_offsets(input_objects
);
2320 // Process any symbol assignments from a linker script. This must
2321 // be called after the symbol table has been finalized.
2322 this->script_options_
->finalize_symbols(symtab
, this);
2324 // Create the incremental inputs sections.
2325 if (this->incremental_inputs_
)
2327 this->incremental_inputs_
->finalize();
2328 this->create_incremental_info_sections(symtab
);
2331 // Create the .shstrtab section.
2332 Output_section
* shstrtab_section
= this->create_shstrtab();
2334 // Set the file offsets of the rest of the non-data sections which
2335 // don't have to wait for the input sections.
2336 off
= this->set_section_offsets(off
, BEFORE_INPUT_SECTIONS_PASS
);
2338 // Now that all sections have been created, set the section indexes
2339 // for any sections which haven't been done yet.
2340 shndx
= this->set_section_indexes(shndx
);
2342 // Create the section table header.
2343 this->create_shdrs(shstrtab_section
, &off
);
2345 // If there are no sections which require postprocessing, we can
2346 // handle the section names now, and avoid a resize later.
2347 if (!this->any_postprocessing_sections_
)
2349 off
= this->set_section_offsets(off
,
2350 POSTPROCESSING_SECTIONS_PASS
);
2352 this->set_section_offsets(off
,
2353 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
);
2356 file_header
->set_section_info(this->section_headers_
, shstrtab_section
);
2358 // Now we know exactly where everything goes in the output file
2359 // (except for non-allocated sections which require postprocessing).
2360 Output_data::layout_complete();
2362 this->output_file_size_
= off
;
2367 // Create a note header following the format defined in the ELF ABI.
2368 // NAME is the name, NOTE_TYPE is the type, SECTION_NAME is the name
2369 // of the section to create, DESCSZ is the size of the descriptor.
2370 // ALLOCATE is true if the section should be allocated in memory.
2371 // This returns the new note section. It sets *TRAILING_PADDING to
2372 // the number of trailing zero bytes required.
2375 Layout::create_note(const char* name
, int note_type
,
2376 const char* section_name
, size_t descsz
,
2377 bool allocate
, size_t* trailing_padding
)
2379 // Authorities all agree that the values in a .note field should
2380 // be aligned on 4-byte boundaries for 32-bit binaries. However,
2381 // they differ on what the alignment is for 64-bit binaries.
2382 // The GABI says unambiguously they take 8-byte alignment:
2383 // http://sco.com/developers/gabi/latest/ch5.pheader.html#note_section
2384 // Other documentation says alignment should always be 4 bytes:
2385 // http://www.netbsd.org/docs/kernel/elf-notes.html#note-format
2386 // GNU ld and GNU readelf both support the latter (at least as of
2387 // version 2.16.91), and glibc always generates the latter for
2388 // .note.ABI-tag (as of version 1.6), so that's the one we go with
2390 #ifdef GABI_FORMAT_FOR_DOTNOTE_SECTION // This is not defined by default.
2391 const int size
= parameters
->target().get_size();
2393 const int size
= 32;
2396 // The contents of the .note section.
2397 size_t namesz
= strlen(name
) + 1;
2398 size_t aligned_namesz
= align_address(namesz
, size
/ 8);
2399 size_t aligned_descsz
= align_address(descsz
, size
/ 8);
2401 size_t notehdrsz
= 3 * (size
/ 8) + aligned_namesz
;
2403 unsigned char* buffer
= new unsigned char[notehdrsz
];
2404 memset(buffer
, 0, notehdrsz
);
2406 bool is_big_endian
= parameters
->target().is_big_endian();
2412 elfcpp::Swap
<32, false>::writeval(buffer
, namesz
);
2413 elfcpp::Swap
<32, false>::writeval(buffer
+ 4, descsz
);
2414 elfcpp::Swap
<32, false>::writeval(buffer
+ 8, note_type
);
2418 elfcpp::Swap
<32, true>::writeval(buffer
, namesz
);
2419 elfcpp::Swap
<32, true>::writeval(buffer
+ 4, descsz
);
2420 elfcpp::Swap
<32, true>::writeval(buffer
+ 8, note_type
);
2423 else if (size
== 64)
2427 elfcpp::Swap
<64, false>::writeval(buffer
, namesz
);
2428 elfcpp::Swap
<64, false>::writeval(buffer
+ 8, descsz
);
2429 elfcpp::Swap
<64, false>::writeval(buffer
+ 16, note_type
);
2433 elfcpp::Swap
<64, true>::writeval(buffer
, namesz
);
2434 elfcpp::Swap
<64, true>::writeval(buffer
+ 8, descsz
);
2435 elfcpp::Swap
<64, true>::writeval(buffer
+ 16, note_type
);
2441 memcpy(buffer
+ 3 * (size
/ 8), name
, namesz
);
2443 elfcpp::Elf_Xword flags
= 0;
2444 Output_section_order order
= ORDER_INVALID
;
2447 flags
= elfcpp::SHF_ALLOC
;
2448 order
= ORDER_RO_NOTE
;
2450 Output_section
* os
= this->choose_output_section(NULL
, section_name
,
2452 flags
, false, order
, false);
2456 Output_section_data
* posd
= new Output_data_const_buffer(buffer
, notehdrsz
,
2459 os
->add_output_section_data(posd
);
2461 *trailing_padding
= aligned_descsz
- descsz
;
2466 // For an executable or shared library, create a note to record the
2467 // version of gold used to create the binary.
2470 Layout::create_gold_note()
2472 if (parameters
->options().relocatable()
2473 || parameters
->incremental_update())
2476 std::string desc
= std::string("gold ") + gold::get_version_string();
2478 size_t trailing_padding
;
2479 Output_section
* os
= this->create_note("GNU", elfcpp::NT_GNU_GOLD_VERSION
,
2480 ".note.gnu.gold-version", desc
.size(),
2481 false, &trailing_padding
);
2485 Output_section_data
* posd
= new Output_data_const(desc
, 4);
2486 os
->add_output_section_data(posd
);
2488 if (trailing_padding
> 0)
2490 posd
= new Output_data_zero_fill(trailing_padding
, 0);
2491 os
->add_output_section_data(posd
);
2495 // Record whether the stack should be executable. This can be set
2496 // from the command line using the -z execstack or -z noexecstack
2497 // options. Otherwise, if any input file has a .note.GNU-stack
2498 // section with the SHF_EXECINSTR flag set, the stack should be
2499 // executable. Otherwise, if at least one input file a
2500 // .note.GNU-stack section, and some input file has no .note.GNU-stack
2501 // section, we use the target default for whether the stack should be
2502 // executable. Otherwise, we don't generate a stack note. When
2503 // generating a object file, we create a .note.GNU-stack section with
2504 // the appropriate marking. When generating an executable or shared
2505 // library, we create a PT_GNU_STACK segment.
2508 Layout::create_executable_stack_info()
2510 bool is_stack_executable
;
2511 if (parameters
->options().is_execstack_set())
2512 is_stack_executable
= parameters
->options().is_stack_executable();
2513 else if (!this->input_with_gnu_stack_note_
)
2517 if (this->input_requires_executable_stack_
)
2518 is_stack_executable
= true;
2519 else if (this->input_without_gnu_stack_note_
)
2520 is_stack_executable
=
2521 parameters
->target().is_default_stack_executable();
2523 is_stack_executable
= false;
2526 if (parameters
->options().relocatable())
2528 const char* name
= this->namepool_
.add(".note.GNU-stack", false, NULL
);
2529 elfcpp::Elf_Xword flags
= 0;
2530 if (is_stack_executable
)
2531 flags
|= elfcpp::SHF_EXECINSTR
;
2532 this->make_output_section(name
, elfcpp::SHT_PROGBITS
, flags
,
2533 ORDER_INVALID
, false);
2537 if (this->script_options_
->saw_phdrs_clause())
2539 int flags
= elfcpp::PF_R
| elfcpp::PF_W
;
2540 if (is_stack_executable
)
2541 flags
|= elfcpp::PF_X
;
2542 this->make_output_segment(elfcpp::PT_GNU_STACK
, flags
);
2546 // If --build-id was used, set up the build ID note.
2549 Layout::create_build_id()
2551 if (!parameters
->options().user_set_build_id())
2554 const char* style
= parameters
->options().build_id();
2555 if (strcmp(style
, "none") == 0)
2558 // Set DESCSZ to the size of the note descriptor. When possible,
2559 // set DESC to the note descriptor contents.
2562 if (strcmp(style
, "md5") == 0)
2564 else if (strcmp(style
, "sha1") == 0)
2566 else if (strcmp(style
, "uuid") == 0)
2568 const size_t uuidsz
= 128 / 8;
2570 char buffer
[uuidsz
];
2571 memset(buffer
, 0, uuidsz
);
2573 int descriptor
= open_descriptor(-1, "/dev/urandom", O_RDONLY
);
2575 gold_error(_("--build-id=uuid failed: could not open /dev/urandom: %s"),
2579 ssize_t got
= ::read(descriptor
, buffer
, uuidsz
);
2580 release_descriptor(descriptor
, true);
2582 gold_error(_("/dev/urandom: read failed: %s"), strerror(errno
));
2583 else if (static_cast<size_t>(got
) != uuidsz
)
2584 gold_error(_("/dev/urandom: expected %zu bytes, got %zd bytes"),
2588 desc
.assign(buffer
, uuidsz
);
2591 else if (strncmp(style
, "0x", 2) == 0)
2594 const char* p
= style
+ 2;
2597 if (hex_p(p
[0]) && hex_p(p
[1]))
2599 char c
= (hex_value(p
[0]) << 4) | hex_value(p
[1]);
2603 else if (*p
== '-' || *p
== ':')
2606 gold_fatal(_("--build-id argument '%s' not a valid hex number"),
2609 descsz
= desc
.size();
2612 gold_fatal(_("unrecognized --build-id argument '%s'"), style
);
2615 size_t trailing_padding
;
2616 Output_section
* os
= this->create_note("GNU", elfcpp::NT_GNU_BUILD_ID
,
2617 ".note.gnu.build-id", descsz
, true,
2624 // We know the value already, so we fill it in now.
2625 gold_assert(desc
.size() == descsz
);
2627 Output_section_data
* posd
= new Output_data_const(desc
, 4);
2628 os
->add_output_section_data(posd
);
2630 if (trailing_padding
!= 0)
2632 posd
= new Output_data_zero_fill(trailing_padding
, 0);
2633 os
->add_output_section_data(posd
);
2638 // We need to compute a checksum after we have completed the
2640 gold_assert(trailing_padding
== 0);
2641 this->build_id_note_
= new Output_data_zero_fill(descsz
, 4);
2642 os
->add_output_section_data(this->build_id_note_
);
2646 // If we have both .stabXX and .stabXXstr sections, then the sh_link
2647 // field of the former should point to the latter. I'm not sure who
2648 // started this, but the GNU linker does it, and some tools depend
2652 Layout::link_stabs_sections()
2654 if (!this->have_stabstr_section_
)
2657 for (Section_list::iterator p
= this->section_list_
.begin();
2658 p
!= this->section_list_
.end();
2661 if ((*p
)->type() != elfcpp::SHT_STRTAB
)
2664 const char* name
= (*p
)->name();
2665 if (strncmp(name
, ".stab", 5) != 0)
2668 size_t len
= strlen(name
);
2669 if (strcmp(name
+ len
- 3, "str") != 0)
2672 std::string
stab_name(name
, len
- 3);
2673 Output_section
* stab_sec
;
2674 stab_sec
= this->find_output_section(stab_name
.c_str());
2675 if (stab_sec
!= NULL
)
2676 stab_sec
->set_link_section(*p
);
2680 // Create .gnu_incremental_inputs and related sections needed
2681 // for the next run of incremental linking to check what has changed.
2684 Layout::create_incremental_info_sections(Symbol_table
* symtab
)
2686 Incremental_inputs
* incr
= this->incremental_inputs_
;
2688 gold_assert(incr
!= NULL
);
2690 // Create the .gnu_incremental_inputs, _symtab, and _relocs input sections.
2691 incr
->create_data_sections(symtab
);
2693 // Add the .gnu_incremental_inputs section.
2694 const char* incremental_inputs_name
=
2695 this->namepool_
.add(".gnu_incremental_inputs", false, NULL
);
2696 Output_section
* incremental_inputs_os
=
2697 this->make_output_section(incremental_inputs_name
,
2698 elfcpp::SHT_GNU_INCREMENTAL_INPUTS
, 0,
2699 ORDER_INVALID
, false);
2700 incremental_inputs_os
->add_output_section_data(incr
->inputs_section());
2702 // Add the .gnu_incremental_symtab section.
2703 const char* incremental_symtab_name
=
2704 this->namepool_
.add(".gnu_incremental_symtab", false, NULL
);
2705 Output_section
* incremental_symtab_os
=
2706 this->make_output_section(incremental_symtab_name
,
2707 elfcpp::SHT_GNU_INCREMENTAL_SYMTAB
, 0,
2708 ORDER_INVALID
, false);
2709 incremental_symtab_os
->add_output_section_data(incr
->symtab_section());
2710 incremental_symtab_os
->set_entsize(4);
2712 // Add the .gnu_incremental_relocs section.
2713 const char* incremental_relocs_name
=
2714 this->namepool_
.add(".gnu_incremental_relocs", false, NULL
);
2715 Output_section
* incremental_relocs_os
=
2716 this->make_output_section(incremental_relocs_name
,
2717 elfcpp::SHT_GNU_INCREMENTAL_RELOCS
, 0,
2718 ORDER_INVALID
, false);
2719 incremental_relocs_os
->add_output_section_data(incr
->relocs_section());
2720 incremental_relocs_os
->set_entsize(incr
->relocs_entsize());
2722 // Add the .gnu_incremental_got_plt section.
2723 const char* incremental_got_plt_name
=
2724 this->namepool_
.add(".gnu_incremental_got_plt", false, NULL
);
2725 Output_section
* incremental_got_plt_os
=
2726 this->make_output_section(incremental_got_plt_name
,
2727 elfcpp::SHT_GNU_INCREMENTAL_GOT_PLT
, 0,
2728 ORDER_INVALID
, false);
2729 incremental_got_plt_os
->add_output_section_data(incr
->got_plt_section());
2731 // Add the .gnu_incremental_strtab section.
2732 const char* incremental_strtab_name
=
2733 this->namepool_
.add(".gnu_incremental_strtab", false, NULL
);
2734 Output_section
* incremental_strtab_os
= this->make_output_section(incremental_strtab_name
,
2735 elfcpp::SHT_STRTAB
, 0,
2736 ORDER_INVALID
, false);
2737 Output_data_strtab
* strtab_data
=
2738 new Output_data_strtab(incr
->get_stringpool());
2739 incremental_strtab_os
->add_output_section_data(strtab_data
);
2741 incremental_inputs_os
->set_after_input_sections();
2742 incremental_symtab_os
->set_after_input_sections();
2743 incremental_relocs_os
->set_after_input_sections();
2744 incremental_got_plt_os
->set_after_input_sections();
2746 incremental_inputs_os
->set_link_section(incremental_strtab_os
);
2747 incremental_symtab_os
->set_link_section(incremental_inputs_os
);
2748 incremental_relocs_os
->set_link_section(incremental_inputs_os
);
2749 incremental_got_plt_os
->set_link_section(incremental_inputs_os
);
2752 // Return whether SEG1 should be before SEG2 in the output file. This
2753 // is based entirely on the segment type and flags. When this is
2754 // called the segment addresses have normally not yet been set.
2757 Layout::segment_precedes(const Output_segment
* seg1
,
2758 const Output_segment
* seg2
)
2760 elfcpp::Elf_Word type1
= seg1
->type();
2761 elfcpp::Elf_Word type2
= seg2
->type();
2763 // The single PT_PHDR segment is required to precede any loadable
2764 // segment. We simply make it always first.
2765 if (type1
== elfcpp::PT_PHDR
)
2767 gold_assert(type2
!= elfcpp::PT_PHDR
);
2770 if (type2
== elfcpp::PT_PHDR
)
2773 // The single PT_INTERP segment is required to precede any loadable
2774 // segment. We simply make it always second.
2775 if (type1
== elfcpp::PT_INTERP
)
2777 gold_assert(type2
!= elfcpp::PT_INTERP
);
2780 if (type2
== elfcpp::PT_INTERP
)
2783 // We then put PT_LOAD segments before any other segments.
2784 if (type1
== elfcpp::PT_LOAD
&& type2
!= elfcpp::PT_LOAD
)
2786 if (type2
== elfcpp::PT_LOAD
&& type1
!= elfcpp::PT_LOAD
)
2789 // We put the PT_TLS segment last except for the PT_GNU_RELRO
2790 // segment, because that is where the dynamic linker expects to find
2791 // it (this is just for efficiency; other positions would also work
2793 if (type1
== elfcpp::PT_TLS
2794 && type2
!= elfcpp::PT_TLS
2795 && type2
!= elfcpp::PT_GNU_RELRO
)
2797 if (type2
== elfcpp::PT_TLS
2798 && type1
!= elfcpp::PT_TLS
2799 && type1
!= elfcpp::PT_GNU_RELRO
)
2802 // We put the PT_GNU_RELRO segment last, because that is where the
2803 // dynamic linker expects to find it (as with PT_TLS, this is just
2805 if (type1
== elfcpp::PT_GNU_RELRO
&& type2
!= elfcpp::PT_GNU_RELRO
)
2807 if (type2
== elfcpp::PT_GNU_RELRO
&& type1
!= elfcpp::PT_GNU_RELRO
)
2810 const elfcpp::Elf_Word flags1
= seg1
->flags();
2811 const elfcpp::Elf_Word flags2
= seg2
->flags();
2813 // The order of non-PT_LOAD segments is unimportant. We simply sort
2814 // by the numeric segment type and flags values. There should not
2815 // be more than one segment with the same type and flags.
2816 if (type1
!= elfcpp::PT_LOAD
)
2819 return type1
< type2
;
2820 gold_assert(flags1
!= flags2
);
2821 return flags1
< flags2
;
2824 // If the addresses are set already, sort by load address.
2825 if (seg1
->are_addresses_set())
2827 if (!seg2
->are_addresses_set())
2830 unsigned int section_count1
= seg1
->output_section_count();
2831 unsigned int section_count2
= seg2
->output_section_count();
2832 if (section_count1
== 0 && section_count2
> 0)
2834 if (section_count1
> 0 && section_count2
== 0)
2837 uint64_t paddr1
= (seg1
->are_addresses_set()
2839 : seg1
->first_section_load_address());
2840 uint64_t paddr2
= (seg2
->are_addresses_set()
2842 : seg2
->first_section_load_address());
2844 if (paddr1
!= paddr2
)
2845 return paddr1
< paddr2
;
2847 else if (seg2
->are_addresses_set())
2850 // A segment which holds large data comes after a segment which does
2851 // not hold large data.
2852 if (seg1
->is_large_data_segment())
2854 if (!seg2
->is_large_data_segment())
2857 else if (seg2
->is_large_data_segment())
2860 // Otherwise, we sort PT_LOAD segments based on the flags. Readonly
2861 // segments come before writable segments. Then writable segments
2862 // with data come before writable segments without data. Then
2863 // executable segments come before non-executable segments. Then
2864 // the unlikely case of a non-readable segment comes before the
2865 // normal case of a readable segment. If there are multiple
2866 // segments with the same type and flags, we require that the
2867 // address be set, and we sort by virtual address and then physical
2869 if ((flags1
& elfcpp::PF_W
) != (flags2
& elfcpp::PF_W
))
2870 return (flags1
& elfcpp::PF_W
) == 0;
2871 if ((flags1
& elfcpp::PF_W
) != 0
2872 && seg1
->has_any_data_sections() != seg2
->has_any_data_sections())
2873 return seg1
->has_any_data_sections();
2874 if ((flags1
& elfcpp::PF_X
) != (flags2
& elfcpp::PF_X
))
2875 return (flags1
& elfcpp::PF_X
) != 0;
2876 if ((flags1
& elfcpp::PF_R
) != (flags2
& elfcpp::PF_R
))
2877 return (flags1
& elfcpp::PF_R
) == 0;
2879 // We shouldn't get here--we shouldn't create segments which we
2880 // can't distinguish. Unless of course we are using a weird linker
2882 gold_assert(this->script_options_
->saw_phdrs_clause());
2886 // Increase OFF so that it is congruent to ADDR modulo ABI_PAGESIZE.
2889 align_file_offset(off_t off
, uint64_t addr
, uint64_t abi_pagesize
)
2891 uint64_t unsigned_off
= off
;
2892 uint64_t aligned_off
= ((unsigned_off
& ~(abi_pagesize
- 1))
2893 | (addr
& (abi_pagesize
- 1)));
2894 if (aligned_off
< unsigned_off
)
2895 aligned_off
+= abi_pagesize
;
2899 // Set the file offsets of all the segments, and all the sections they
2900 // contain. They have all been created. LOAD_SEG must be be laid out
2901 // first. Return the offset of the data to follow.
2904 Layout::set_segment_offsets(const Target
* target
, Output_segment
* load_seg
,
2905 unsigned int* pshndx
)
2907 // Sort them into the final order. We use a stable sort so that we
2908 // don't randomize the order of indistinguishable segments created
2909 // by linker scripts.
2910 std::stable_sort(this->segment_list_
.begin(), this->segment_list_
.end(),
2911 Layout::Compare_segments(this));
2913 // Find the PT_LOAD segments, and set their addresses and offsets
2914 // and their section's addresses and offsets.
2916 if (parameters
->options().user_set_Ttext())
2917 addr
= parameters
->options().Ttext();
2918 else if (parameters
->options().output_is_position_independent())
2921 addr
= target
->default_text_segment_address();
2924 // If LOAD_SEG is NULL, then the file header and segment headers
2925 // will not be loadable. But they still need to be at offset 0 in
2926 // the file. Set their offsets now.
2927 if (load_seg
== NULL
)
2929 for (Data_list::iterator p
= this->special_output_list_
.begin();
2930 p
!= this->special_output_list_
.end();
2933 off
= align_address(off
, (*p
)->addralign());
2934 (*p
)->set_address_and_file_offset(0, off
);
2935 off
+= (*p
)->data_size();
2939 unsigned int increase_relro
= this->increase_relro_
;
2940 if (this->script_options_
->saw_sections_clause())
2943 const bool check_sections
= parameters
->options().check_sections();
2944 Output_segment
* last_load_segment
= NULL
;
2946 for (Segment_list::iterator p
= this->segment_list_
.begin();
2947 p
!= this->segment_list_
.end();
2950 if ((*p
)->type() == elfcpp::PT_LOAD
)
2952 if (load_seg
!= NULL
&& load_seg
!= *p
)
2956 bool are_addresses_set
= (*p
)->are_addresses_set();
2957 if (are_addresses_set
)
2959 // When it comes to setting file offsets, we care about
2960 // the physical address.
2961 addr
= (*p
)->paddr();
2963 else if (parameters
->options().user_set_Tdata()
2964 && ((*p
)->flags() & elfcpp::PF_W
) != 0
2965 && (!parameters
->options().user_set_Tbss()
2966 || (*p
)->has_any_data_sections()))
2968 addr
= parameters
->options().Tdata();
2969 are_addresses_set
= true;
2971 else if (parameters
->options().user_set_Tbss()
2972 && ((*p
)->flags() & elfcpp::PF_W
) != 0
2973 && !(*p
)->has_any_data_sections())
2975 addr
= parameters
->options().Tbss();
2976 are_addresses_set
= true;
2979 uint64_t orig_addr
= addr
;
2980 uint64_t orig_off
= off
;
2982 uint64_t aligned_addr
= 0;
2983 uint64_t abi_pagesize
= target
->abi_pagesize();
2984 uint64_t common_pagesize
= target
->common_pagesize();
2986 if (!parameters
->options().nmagic()
2987 && !parameters
->options().omagic())
2988 (*p
)->set_minimum_p_align(common_pagesize
);
2990 if (!are_addresses_set
)
2992 // Skip the address forward one page, maintaining the same
2993 // position within the page. This lets us store both segments
2994 // overlapping on a single page in the file, but the loader will
2995 // put them on different pages in memory. We will revisit this
2996 // decision once we know the size of the segment.
2998 addr
= align_address(addr
, (*p
)->maximum_alignment());
2999 aligned_addr
= addr
;
3001 if ((addr
& (abi_pagesize
- 1)) != 0)
3002 addr
= addr
+ abi_pagesize
;
3004 off
= orig_off
+ ((addr
- orig_addr
) & (abi_pagesize
- 1));
3007 if (!parameters
->options().nmagic()
3008 && !parameters
->options().omagic())
3009 off
= align_file_offset(off
, addr
, abi_pagesize
);
3010 else if (load_seg
== NULL
)
3012 // This is -N or -n with a section script which prevents
3013 // us from using a load segment. We need to ensure that
3014 // the file offset is aligned to the alignment of the
3015 // segment. This is because the linker script
3016 // implicitly assumed a zero offset. If we don't align
3017 // here, then the alignment of the sections in the
3018 // linker script may not match the alignment of the
3019 // sections in the set_section_addresses call below,
3020 // causing an error about dot moving backward.
3021 off
= align_address(off
, (*p
)->maximum_alignment());
3024 unsigned int shndx_hold
= *pshndx
;
3025 bool has_relro
= false;
3026 uint64_t new_addr
= (*p
)->set_section_addresses(this, false, addr
,
3031 // Now that we know the size of this segment, we may be able
3032 // to save a page in memory, at the cost of wasting some
3033 // file space, by instead aligning to the start of a new
3034 // page. Here we use the real machine page size rather than
3035 // the ABI mandated page size. If the segment has been
3036 // aligned so that the relro data ends at a page boundary,
3037 // we do not try to realign it.
3039 if (!are_addresses_set
3041 && aligned_addr
!= addr
3042 && !parameters
->incremental())
3044 uint64_t first_off
= (common_pagesize
3046 & (common_pagesize
- 1)));
3047 uint64_t last_off
= new_addr
& (common_pagesize
- 1);
3050 && ((aligned_addr
& ~ (common_pagesize
- 1))
3051 != (new_addr
& ~ (common_pagesize
- 1)))
3052 && first_off
+ last_off
<= common_pagesize
)
3054 *pshndx
= shndx_hold
;
3055 addr
= align_address(aligned_addr
, common_pagesize
);
3056 addr
= align_address(addr
, (*p
)->maximum_alignment());
3057 off
= orig_off
+ ((addr
- orig_addr
) & (abi_pagesize
- 1));
3058 off
= align_file_offset(off
, addr
, abi_pagesize
);
3060 increase_relro
= this->increase_relro_
;
3061 if (this->script_options_
->saw_sections_clause())
3065 new_addr
= (*p
)->set_section_addresses(this, true, addr
,
3074 // Implement --check-sections. We know that the segments
3075 // are sorted by LMA.
3076 if (check_sections
&& last_load_segment
!= NULL
)
3078 gold_assert(last_load_segment
->paddr() <= (*p
)->paddr());
3079 if (last_load_segment
->paddr() + last_load_segment
->memsz()
3082 unsigned long long lb1
= last_load_segment
->paddr();
3083 unsigned long long le1
= lb1
+ last_load_segment
->memsz();
3084 unsigned long long lb2
= (*p
)->paddr();
3085 unsigned long long le2
= lb2
+ (*p
)->memsz();
3086 gold_error(_("load segment overlap [0x%llx -> 0x%llx] and "
3087 "[0x%llx -> 0x%llx]"),
3088 lb1
, le1
, lb2
, le2
);
3091 last_load_segment
= *p
;
3095 // Handle the non-PT_LOAD segments, setting their offsets from their
3096 // section's offsets.
3097 for (Segment_list::iterator p
= this->segment_list_
.begin();
3098 p
!= this->segment_list_
.end();
3101 if ((*p
)->type() != elfcpp::PT_LOAD
)
3102 (*p
)->set_offset((*p
)->type() == elfcpp::PT_GNU_RELRO
3107 // Set the TLS offsets for each section in the PT_TLS segment.
3108 if (this->tls_segment_
!= NULL
)
3109 this->tls_segment_
->set_tls_offsets();
3114 // Set the offsets of all the allocated sections when doing a
3115 // relocatable link. This does the same jobs as set_segment_offsets,
3116 // only for a relocatable link.
3119 Layout::set_relocatable_section_offsets(Output_data
* file_header
,
3120 unsigned int* pshndx
)
3124 file_header
->set_address_and_file_offset(0, 0);
3125 off
+= file_header
->data_size();
3127 for (Section_list::iterator p
= this->section_list_
.begin();
3128 p
!= this->section_list_
.end();
3131 // We skip unallocated sections here, except that group sections
3132 // have to come first.
3133 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) == 0
3134 && (*p
)->type() != elfcpp::SHT_GROUP
)
3137 off
= align_address(off
, (*p
)->addralign());
3139 // The linker script might have set the address.
3140 if (!(*p
)->is_address_valid())
3141 (*p
)->set_address(0);
3142 (*p
)->set_file_offset(off
);
3143 (*p
)->finalize_data_size();
3144 off
+= (*p
)->data_size();
3146 (*p
)->set_out_shndx(*pshndx
);
3153 // Set the file offset of all the sections not associated with a
3157 Layout::set_section_offsets(off_t off
, Layout::Section_offset_pass pass
)
3159 off_t startoff
= off
;
3162 for (Section_list::iterator p
= this->unattached_section_list_
.begin();
3163 p
!= this->unattached_section_list_
.end();
3166 // The symtab section is handled in create_symtab_sections.
3167 if (*p
== this->symtab_section_
)
3170 // If we've already set the data size, don't set it again.
3171 if ((*p
)->is_offset_valid() && (*p
)->is_data_size_valid())
3174 if (pass
== BEFORE_INPUT_SECTIONS_PASS
3175 && (*p
)->requires_postprocessing())
3177 (*p
)->create_postprocessing_buffer();
3178 this->any_postprocessing_sections_
= true;
3181 if (pass
== BEFORE_INPUT_SECTIONS_PASS
3182 && (*p
)->after_input_sections())
3184 else if (pass
== POSTPROCESSING_SECTIONS_PASS
3185 && (!(*p
)->after_input_sections()
3186 || (*p
)->type() == elfcpp::SHT_STRTAB
))
3188 else if (pass
== STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
3189 && (!(*p
)->after_input_sections()
3190 || (*p
)->type() != elfcpp::SHT_STRTAB
))
3193 if (!parameters
->incremental_update())
3195 off
= align_address(off
, (*p
)->addralign());
3196 (*p
)->set_file_offset(off
);
3197 (*p
)->finalize_data_size();
3201 // Incremental update: allocate file space from free list.
3202 (*p
)->pre_finalize_data_size();
3203 off_t current_size
= (*p
)->current_data_size();
3204 off
= this->allocate(current_size
, (*p
)->addralign(), startoff
);
3207 if (is_debugging_enabled(DEBUG_INCREMENTAL
))
3208 this->free_list_
.dump();
3209 gold_assert((*p
)->output_section() != NULL
);
3210 gold_fallback(_("out of patch space for section %s; "
3211 "relink with --incremental-full"),
3212 (*p
)->output_section()->name());
3214 (*p
)->set_file_offset(off
);
3215 (*p
)->finalize_data_size();
3216 if ((*p
)->data_size() > current_size
)
3218 gold_assert((*p
)->output_section() != NULL
);
3219 gold_fallback(_("%s: section changed size; "
3220 "relink with --incremental-full"),
3221 (*p
)->output_section()->name());
3223 gold_debug(DEBUG_INCREMENTAL
,
3224 "set_section_offsets: %08lx %08lx %s",
3225 static_cast<long>(off
),
3226 static_cast<long>((*p
)->data_size()),
3227 ((*p
)->output_section() != NULL
3228 ? (*p
)->output_section()->name() : "(special)"));
3231 off
+= (*p
)->data_size();
3235 // At this point the name must be set.
3236 if (pass
!= STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
)
3237 this->namepool_
.add((*p
)->name(), false, NULL
);
3242 // Set the section indexes of all the sections not associated with a
3246 Layout::set_section_indexes(unsigned int shndx
)
3248 for (Section_list::iterator p
= this->unattached_section_list_
.begin();
3249 p
!= this->unattached_section_list_
.end();
3252 if (!(*p
)->has_out_shndx())
3254 (*p
)->set_out_shndx(shndx
);
3261 // Set the section addresses according to the linker script. This is
3262 // only called when we see a SECTIONS clause. This returns the
3263 // program segment which should hold the file header and segment
3264 // headers, if any. It will return NULL if they should not be in a
3268 Layout::set_section_addresses_from_script(Symbol_table
* symtab
)
3270 Script_sections
* ss
= this->script_options_
->script_sections();
3271 gold_assert(ss
->saw_sections_clause());
3272 return this->script_options_
->set_section_addresses(symtab
, this);
3275 // Place the orphan sections in the linker script.
3278 Layout::place_orphan_sections_in_script()
3280 Script_sections
* ss
= this->script_options_
->script_sections();
3281 gold_assert(ss
->saw_sections_clause());
3283 // Place each orphaned output section in the script.
3284 for (Section_list::iterator p
= this->section_list_
.begin();
3285 p
!= this->section_list_
.end();
3288 if (!(*p
)->found_in_sections_clause())
3289 ss
->place_orphan(*p
);
3293 // Count the local symbols in the regular symbol table and the dynamic
3294 // symbol table, and build the respective string pools.
3297 Layout::count_local_symbols(const Task
* task
,
3298 const Input_objects
* input_objects
)
3300 // First, figure out an upper bound on the number of symbols we'll
3301 // be inserting into each pool. This helps us create the pools with
3302 // the right size, to avoid unnecessary hashtable resizing.
3303 unsigned int symbol_count
= 0;
3304 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
3305 p
!= input_objects
->relobj_end();
3307 symbol_count
+= (*p
)->local_symbol_count();
3309 // Go from "upper bound" to "estimate." We overcount for two
3310 // reasons: we double-count symbols that occur in more than one
3311 // object file, and we count symbols that are dropped from the
3312 // output. Add it all together and assume we overcount by 100%.
3315 // We assume all symbols will go into both the sympool and dynpool.
3316 this->sympool_
.reserve(symbol_count
);
3317 this->dynpool_
.reserve(symbol_count
);
3319 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
3320 p
!= input_objects
->relobj_end();
3323 Task_lock_obj
<Object
> tlo(task
, *p
);
3324 (*p
)->count_local_symbols(&this->sympool_
, &this->dynpool_
);
3328 // Create the symbol table sections. Here we also set the final
3329 // values of the symbols. At this point all the loadable sections are
3330 // fully laid out. SHNUM is the number of sections so far.
3333 Layout::create_symtab_sections(const Input_objects
* input_objects
,
3334 Symbol_table
* symtab
,
3340 if (parameters
->target().get_size() == 32)
3342 symsize
= elfcpp::Elf_sizes
<32>::sym_size
;
3345 else if (parameters
->target().get_size() == 64)
3347 symsize
= elfcpp::Elf_sizes
<64>::sym_size
;
3353 // Compute file offsets relative to the start of the symtab section.
3356 // Save space for the dummy symbol at the start of the section. We
3357 // never bother to write this out--it will just be left as zero.
3359 unsigned int local_symbol_index
= 1;
3361 // Add STT_SECTION symbols for each Output section which needs one.
3362 for (Section_list::iterator p
= this->section_list_
.begin();
3363 p
!= this->section_list_
.end();
3366 if (!(*p
)->needs_symtab_index())
3367 (*p
)->set_symtab_index(-1U);
3370 (*p
)->set_symtab_index(local_symbol_index
);
3371 ++local_symbol_index
;
3376 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
3377 p
!= input_objects
->relobj_end();
3380 unsigned int index
= (*p
)->finalize_local_symbols(local_symbol_index
,
3382 off
+= (index
- local_symbol_index
) * symsize
;
3383 local_symbol_index
= index
;
3386 unsigned int local_symcount
= local_symbol_index
;
3387 gold_assert(static_cast<off_t
>(local_symcount
* symsize
) == off
);
3390 size_t dyn_global_index
;
3392 if (this->dynsym_section_
== NULL
)
3395 dyn_global_index
= 0;
3400 dyn_global_index
= this->dynsym_section_
->info();
3401 off_t locsize
= dyn_global_index
* this->dynsym_section_
->entsize();
3402 dynoff
= this->dynsym_section_
->offset() + locsize
;
3403 dyncount
= (this->dynsym_section_
->data_size() - locsize
) / symsize
;
3404 gold_assert(static_cast<off_t
>(dyncount
* symsize
)
3405 == this->dynsym_section_
->data_size() - locsize
);
3408 off_t global_off
= off
;
3409 off
= symtab
->finalize(off
, dynoff
, dyn_global_index
, dyncount
,
3410 &this->sympool_
, &local_symcount
);
3412 if (!parameters
->options().strip_all())
3414 this->sympool_
.set_string_offsets();
3416 const char* symtab_name
= this->namepool_
.add(".symtab", false, NULL
);
3417 Output_section
* osymtab
= this->make_output_section(symtab_name
,
3421 this->symtab_section_
= osymtab
;
3423 Output_section_data
* pos
= new Output_data_fixed_space(off
, align
,
3425 osymtab
->add_output_section_data(pos
);
3427 // We generate a .symtab_shndx section if we have more than
3428 // SHN_LORESERVE sections. Technically it is possible that we
3429 // don't need one, because it is possible that there are no
3430 // symbols in any of sections with indexes larger than
3431 // SHN_LORESERVE. That is probably unusual, though, and it is
3432 // easier to always create one than to compute section indexes
3433 // twice (once here, once when writing out the symbols).
3434 if (shnum
>= elfcpp::SHN_LORESERVE
)
3436 const char* symtab_xindex_name
= this->namepool_
.add(".symtab_shndx",
3438 Output_section
* osymtab_xindex
=
3439 this->make_output_section(symtab_xindex_name
,
3440 elfcpp::SHT_SYMTAB_SHNDX
, 0,
3441 ORDER_INVALID
, false);
3443 size_t symcount
= off
/ symsize
;
3444 this->symtab_xindex_
= new Output_symtab_xindex(symcount
);
3446 osymtab_xindex
->add_output_section_data(this->symtab_xindex_
);
3448 osymtab_xindex
->set_link_section(osymtab
);
3449 osymtab_xindex
->set_addralign(4);
3450 osymtab_xindex
->set_entsize(4);
3452 osymtab_xindex
->set_after_input_sections();
3454 // This tells the driver code to wait until the symbol table
3455 // has written out before writing out the postprocessing
3456 // sections, including the .symtab_shndx section.
3457 this->any_postprocessing_sections_
= true;
3460 const char* strtab_name
= this->namepool_
.add(".strtab", false, NULL
);
3461 Output_section
* ostrtab
= this->make_output_section(strtab_name
,
3466 Output_section_data
* pstr
= new Output_data_strtab(&this->sympool_
);
3467 ostrtab
->add_output_section_data(pstr
);
3470 if (!parameters
->incremental_update())
3471 symtab_off
= align_address(*poff
, align
);
3474 symtab_off
= this->allocate(off
, align
, *poff
);
3476 gold_fallback(_("out of patch space for symbol table; "
3477 "relink with --incremental-full"));
3478 gold_debug(DEBUG_INCREMENTAL
,
3479 "create_symtab_sections: %08lx %08lx .symtab",
3480 static_cast<long>(symtab_off
),
3481 static_cast<long>(off
));
3484 symtab
->set_file_offset(symtab_off
+ global_off
);
3485 osymtab
->set_file_offset(symtab_off
);
3486 osymtab
->finalize_data_size();
3487 osymtab
->set_link_section(ostrtab
);
3488 osymtab
->set_info(local_symcount
);
3489 osymtab
->set_entsize(symsize
);
3491 if (symtab_off
+ off
> *poff
)
3492 *poff
= symtab_off
+ off
;
3496 // Create the .shstrtab section, which holds the names of the
3497 // sections. At the time this is called, we have created all the
3498 // output sections except .shstrtab itself.
3501 Layout::create_shstrtab()
3503 // FIXME: We don't need to create a .shstrtab section if we are
3504 // stripping everything.
3506 const char* name
= this->namepool_
.add(".shstrtab", false, NULL
);
3508 Output_section
* os
= this->make_output_section(name
, elfcpp::SHT_STRTAB
, 0,
3509 ORDER_INVALID
, false);
3511 if (strcmp(parameters
->options().compress_debug_sections(), "none") != 0)
3513 // We can't write out this section until we've set all the
3514 // section names, and we don't set the names of compressed
3515 // output sections until relocations are complete. FIXME: With
3516 // the current names we use, this is unnecessary.
3517 os
->set_after_input_sections();
3520 Output_section_data
* posd
= new Output_data_strtab(&this->namepool_
);
3521 os
->add_output_section_data(posd
);
3526 // Create the section headers. SIZE is 32 or 64. OFF is the file
3530 Layout::create_shdrs(const Output_section
* shstrtab_section
, off_t
* poff
)
3532 Output_section_headers
* oshdrs
;
3533 oshdrs
= new Output_section_headers(this,
3534 &this->segment_list_
,
3535 &this->section_list_
,
3536 &this->unattached_section_list_
,
3540 if (!parameters
->incremental_update())
3541 off
= align_address(*poff
, oshdrs
->addralign());
3544 oshdrs
->pre_finalize_data_size();
3545 off
= this->allocate(oshdrs
->data_size(), oshdrs
->addralign(), *poff
);
3547 gold_fallback(_("out of patch space for section header table; "
3548 "relink with --incremental-full"));
3549 gold_debug(DEBUG_INCREMENTAL
,
3550 "create_shdrs: %08lx %08lx (section header table)",
3551 static_cast<long>(off
),
3552 static_cast<long>(off
+ oshdrs
->data_size()));
3554 oshdrs
->set_address_and_file_offset(0, off
);
3555 off
+= oshdrs
->data_size();
3558 this->section_headers_
= oshdrs
;
3561 // Count the allocated sections.
3564 Layout::allocated_output_section_count() const
3566 size_t section_count
= 0;
3567 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
3568 p
!= this->segment_list_
.end();
3570 section_count
+= (*p
)->output_section_count();
3571 return section_count
;
3574 // Create the dynamic symbol table.
3577 Layout::create_dynamic_symtab(const Input_objects
* input_objects
,
3578 Symbol_table
* symtab
,
3579 Output_section
** pdynstr
,
3580 unsigned int* plocal_dynamic_count
,
3581 std::vector
<Symbol
*>* pdynamic_symbols
,
3582 Versions
* pversions
)
3584 // Count all the symbols in the dynamic symbol table, and set the
3585 // dynamic symbol indexes.
3587 // Skip symbol 0, which is always all zeroes.
3588 unsigned int index
= 1;
3590 // Add STT_SECTION symbols for each Output section which needs one.
3591 for (Section_list::iterator p
= this->section_list_
.begin();
3592 p
!= this->section_list_
.end();
3595 if (!(*p
)->needs_dynsym_index())
3596 (*p
)->set_dynsym_index(-1U);
3599 (*p
)->set_dynsym_index(index
);
3604 // Count the local symbols that need to go in the dynamic symbol table,
3605 // and set the dynamic symbol indexes.
3606 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
3607 p
!= input_objects
->relobj_end();
3610 unsigned int new_index
= (*p
)->set_local_dynsym_indexes(index
);
3614 unsigned int local_symcount
= index
;
3615 *plocal_dynamic_count
= local_symcount
;
3617 index
= symtab
->set_dynsym_indexes(index
, pdynamic_symbols
,
3618 &this->dynpool_
, pversions
);
3622 const int size
= parameters
->target().get_size();
3625 symsize
= elfcpp::Elf_sizes
<32>::sym_size
;
3628 else if (size
== 64)
3630 symsize
= elfcpp::Elf_sizes
<64>::sym_size
;
3636 // Create the dynamic symbol table section.
3638 Output_section
* dynsym
= this->choose_output_section(NULL
, ".dynsym",
3642 ORDER_DYNAMIC_LINKER
,
3645 Output_section_data
* odata
= new Output_data_fixed_space(index
* symsize
,
3648 dynsym
->add_output_section_data(odata
);
3650 dynsym
->set_info(local_symcount
);
3651 dynsym
->set_entsize(symsize
);
3652 dynsym
->set_addralign(align
);
3654 this->dynsym_section_
= dynsym
;
3656 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
3657 odyn
->add_section_address(elfcpp::DT_SYMTAB
, dynsym
);
3658 odyn
->add_constant(elfcpp::DT_SYMENT
, symsize
);
3660 // If there are more than SHN_LORESERVE allocated sections, we
3661 // create a .dynsym_shndx section. It is possible that we don't
3662 // need one, because it is possible that there are no dynamic
3663 // symbols in any of the sections with indexes larger than
3664 // SHN_LORESERVE. This is probably unusual, though, and at this
3665 // time we don't know the actual section indexes so it is
3666 // inconvenient to check.
3667 if (this->allocated_output_section_count() >= elfcpp::SHN_LORESERVE
)
3669 Output_section
* dynsym_xindex
=
3670 this->choose_output_section(NULL
, ".dynsym_shndx",
3671 elfcpp::SHT_SYMTAB_SHNDX
,
3673 false, ORDER_DYNAMIC_LINKER
, false);
3675 this->dynsym_xindex_
= new Output_symtab_xindex(index
);
3677 dynsym_xindex
->add_output_section_data(this->dynsym_xindex_
);
3679 dynsym_xindex
->set_link_section(dynsym
);
3680 dynsym_xindex
->set_addralign(4);
3681 dynsym_xindex
->set_entsize(4);
3683 dynsym_xindex
->set_after_input_sections();
3685 // This tells the driver code to wait until the symbol table has
3686 // written out before writing out the postprocessing sections,
3687 // including the .dynsym_shndx section.
3688 this->any_postprocessing_sections_
= true;
3691 // Create the dynamic string table section.
3693 Output_section
* dynstr
= this->choose_output_section(NULL
, ".dynstr",
3697 ORDER_DYNAMIC_LINKER
,
3700 Output_section_data
* strdata
= new Output_data_strtab(&this->dynpool_
);
3701 dynstr
->add_output_section_data(strdata
);
3703 dynsym
->set_link_section(dynstr
);
3704 this->dynamic_section_
->set_link_section(dynstr
);
3706 odyn
->add_section_address(elfcpp::DT_STRTAB
, dynstr
);
3707 odyn
->add_section_size(elfcpp::DT_STRSZ
, dynstr
);
3711 // Create the hash tables.
3713 if (strcmp(parameters
->options().hash_style(), "sysv") == 0
3714 || strcmp(parameters
->options().hash_style(), "both") == 0)
3716 unsigned char* phash
;
3717 unsigned int hashlen
;
3718 Dynobj::create_elf_hash_table(*pdynamic_symbols
, local_symcount
,
3721 Output_section
* hashsec
=
3722 this->choose_output_section(NULL
, ".hash", elfcpp::SHT_HASH
,
3723 elfcpp::SHF_ALLOC
, false,
3724 ORDER_DYNAMIC_LINKER
, false);
3726 Output_section_data
* hashdata
= new Output_data_const_buffer(phash
,
3730 hashsec
->add_output_section_data(hashdata
);
3732 hashsec
->set_link_section(dynsym
);
3733 hashsec
->set_entsize(4);
3735 odyn
->add_section_address(elfcpp::DT_HASH
, hashsec
);
3738 if (strcmp(parameters
->options().hash_style(), "gnu") == 0
3739 || strcmp(parameters
->options().hash_style(), "both") == 0)
3741 unsigned char* phash
;
3742 unsigned int hashlen
;
3743 Dynobj::create_gnu_hash_table(*pdynamic_symbols
, local_symcount
,
3746 Output_section
* hashsec
=
3747 this->choose_output_section(NULL
, ".gnu.hash", elfcpp::SHT_GNU_HASH
,
3748 elfcpp::SHF_ALLOC
, false,
3749 ORDER_DYNAMIC_LINKER
, false);
3751 Output_section_data
* hashdata
= new Output_data_const_buffer(phash
,
3755 hashsec
->add_output_section_data(hashdata
);
3757 hashsec
->set_link_section(dynsym
);
3759 // For a 64-bit target, the entries in .gnu.hash do not have a
3760 // uniform size, so we only set the entry size for a 32-bit
3762 if (parameters
->target().get_size() == 32)
3763 hashsec
->set_entsize(4);
3765 odyn
->add_section_address(elfcpp::DT_GNU_HASH
, hashsec
);
3769 // Assign offsets to each local portion of the dynamic symbol table.
3772 Layout::assign_local_dynsym_offsets(const Input_objects
* input_objects
)
3774 Output_section
* dynsym
= this->dynsym_section_
;
3775 gold_assert(dynsym
!= NULL
);
3777 off_t off
= dynsym
->offset();
3779 // Skip the dummy symbol at the start of the section.
3780 off
+= dynsym
->entsize();
3782 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
3783 p
!= input_objects
->relobj_end();
3786 unsigned int count
= (*p
)->set_local_dynsym_offset(off
);
3787 off
+= count
* dynsym
->entsize();
3791 // Create the version sections.
3794 Layout::create_version_sections(const Versions
* versions
,
3795 const Symbol_table
* symtab
,
3796 unsigned int local_symcount
,
3797 const std::vector
<Symbol
*>& dynamic_symbols
,
3798 const Output_section
* dynstr
)
3800 if (!versions
->any_defs() && !versions
->any_needs())
3803 switch (parameters
->size_and_endianness())
3805 #ifdef HAVE_TARGET_32_LITTLE
3806 case Parameters::TARGET_32_LITTLE
:
3807 this->sized_create_version_sections
<32, false>(versions
, symtab
,
3809 dynamic_symbols
, dynstr
);
3812 #ifdef HAVE_TARGET_32_BIG
3813 case Parameters::TARGET_32_BIG
:
3814 this->sized_create_version_sections
<32, true>(versions
, symtab
,
3816 dynamic_symbols
, dynstr
);
3819 #ifdef HAVE_TARGET_64_LITTLE
3820 case Parameters::TARGET_64_LITTLE
:
3821 this->sized_create_version_sections
<64, false>(versions
, symtab
,
3823 dynamic_symbols
, dynstr
);
3826 #ifdef HAVE_TARGET_64_BIG
3827 case Parameters::TARGET_64_BIG
:
3828 this->sized_create_version_sections
<64, true>(versions
, symtab
,
3830 dynamic_symbols
, dynstr
);
3838 // Create the version sections, sized version.
3840 template<int size
, bool big_endian
>
3842 Layout::sized_create_version_sections(
3843 const Versions
* versions
,
3844 const Symbol_table
* symtab
,
3845 unsigned int local_symcount
,
3846 const std::vector
<Symbol
*>& dynamic_symbols
,
3847 const Output_section
* dynstr
)
3849 Output_section
* vsec
= this->choose_output_section(NULL
, ".gnu.version",
3850 elfcpp::SHT_GNU_versym
,
3853 ORDER_DYNAMIC_LINKER
,
3856 unsigned char* vbuf
;
3858 versions
->symbol_section_contents
<size
, big_endian
>(symtab
, &this->dynpool_
,
3863 Output_section_data
* vdata
= new Output_data_const_buffer(vbuf
, vsize
, 2,
3866 vsec
->add_output_section_data(vdata
);
3867 vsec
->set_entsize(2);
3868 vsec
->set_link_section(this->dynsym_section_
);
3870 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
3871 odyn
->add_section_address(elfcpp::DT_VERSYM
, vsec
);
3873 if (versions
->any_defs())
3875 Output_section
* vdsec
;
3876 vdsec
= this->choose_output_section(NULL
, ".gnu.version_d",
3877 elfcpp::SHT_GNU_verdef
,
3879 false, ORDER_DYNAMIC_LINKER
, false);
3881 unsigned char* vdbuf
;
3882 unsigned int vdsize
;
3883 unsigned int vdentries
;
3884 versions
->def_section_contents
<size
, big_endian
>(&this->dynpool_
, &vdbuf
,
3885 &vdsize
, &vdentries
);
3887 Output_section_data
* vddata
=
3888 new Output_data_const_buffer(vdbuf
, vdsize
, 4, "** version defs");
3890 vdsec
->add_output_section_data(vddata
);
3891 vdsec
->set_link_section(dynstr
);
3892 vdsec
->set_info(vdentries
);
3894 odyn
->add_section_address(elfcpp::DT_VERDEF
, vdsec
);
3895 odyn
->add_constant(elfcpp::DT_VERDEFNUM
, vdentries
);
3898 if (versions
->any_needs())
3900 Output_section
* vnsec
;
3901 vnsec
= this->choose_output_section(NULL
, ".gnu.version_r",
3902 elfcpp::SHT_GNU_verneed
,
3904 false, ORDER_DYNAMIC_LINKER
, false);
3906 unsigned char* vnbuf
;
3907 unsigned int vnsize
;
3908 unsigned int vnentries
;
3909 versions
->need_section_contents
<size
, big_endian
>(&this->dynpool_
,
3913 Output_section_data
* vndata
=
3914 new Output_data_const_buffer(vnbuf
, vnsize
, 4, "** version refs");
3916 vnsec
->add_output_section_data(vndata
);
3917 vnsec
->set_link_section(dynstr
);
3918 vnsec
->set_info(vnentries
);
3920 odyn
->add_section_address(elfcpp::DT_VERNEED
, vnsec
);
3921 odyn
->add_constant(elfcpp::DT_VERNEEDNUM
, vnentries
);
3925 // Create the .interp section and PT_INTERP segment.
3928 Layout::create_interp(const Target
* target
)
3930 gold_assert(this->interp_segment_
== NULL
);
3932 const char* interp
= parameters
->options().dynamic_linker();
3935 interp
= target
->dynamic_linker();
3936 gold_assert(interp
!= NULL
);
3939 size_t len
= strlen(interp
) + 1;
3941 Output_section_data
* odata
= new Output_data_const(interp
, len
, 1);
3943 Output_section
* osec
= this->choose_output_section(NULL
, ".interp",
3944 elfcpp::SHT_PROGBITS
,
3946 false, ORDER_INTERP
,
3948 osec
->add_output_section_data(odata
);
3951 // Add dynamic tags for the PLT and the dynamic relocs. This is
3952 // called by the target-specific code. This does nothing if not doing
3955 // USE_REL is true for REL relocs rather than RELA relocs.
3957 // If PLT_GOT is not NULL, then DT_PLTGOT points to it.
3959 // If PLT_REL is not NULL, it is used for DT_PLTRELSZ, and DT_JMPREL,
3960 // and we also set DT_PLTREL. We use PLT_REL's output section, since
3961 // some targets have multiple reloc sections in PLT_REL.
3963 // If DYN_REL is not NULL, it is used for DT_REL/DT_RELA,
3964 // DT_RELSZ/DT_RELASZ, DT_RELENT/DT_RELAENT.
3966 // If ADD_DEBUG is true, we add a DT_DEBUG entry when generating an
3970 Layout::add_target_dynamic_tags(bool use_rel
, const Output_data
* plt_got
,
3971 const Output_data
* plt_rel
,
3972 const Output_data_reloc_generic
* dyn_rel
,
3973 bool add_debug
, bool dynrel_includes_plt
)
3975 Output_data_dynamic
* odyn
= this->dynamic_data_
;
3979 if (plt_got
!= NULL
&& plt_got
->output_section() != NULL
)
3980 odyn
->add_section_address(elfcpp::DT_PLTGOT
, plt_got
);
3982 if (plt_rel
!= NULL
&& plt_rel
->output_section() != NULL
)
3984 odyn
->add_section_size(elfcpp::DT_PLTRELSZ
, plt_rel
->output_section());
3985 odyn
->add_section_address(elfcpp::DT_JMPREL
, plt_rel
->output_section());
3986 odyn
->add_constant(elfcpp::DT_PLTREL
,
3987 use_rel
? elfcpp::DT_REL
: elfcpp::DT_RELA
);
3990 if (dyn_rel
!= NULL
&& dyn_rel
->output_section() != NULL
)
3992 odyn
->add_section_address(use_rel
? elfcpp::DT_REL
: elfcpp::DT_RELA
,
3994 if (plt_rel
!= NULL
&& dynrel_includes_plt
)
3995 odyn
->add_section_size(use_rel
? elfcpp::DT_RELSZ
: elfcpp::DT_RELASZ
,
3998 odyn
->add_section_size(use_rel
? elfcpp::DT_RELSZ
: elfcpp::DT_RELASZ
,
4000 const int size
= parameters
->target().get_size();
4005 rel_tag
= elfcpp::DT_RELENT
;
4007 rel_size
= Reloc_types
<elfcpp::SHT_REL
, 32, false>::reloc_size
;
4008 else if (size
== 64)
4009 rel_size
= Reloc_types
<elfcpp::SHT_REL
, 64, false>::reloc_size
;
4015 rel_tag
= elfcpp::DT_RELAENT
;
4017 rel_size
= Reloc_types
<elfcpp::SHT_RELA
, 32, false>::reloc_size
;
4018 else if (size
== 64)
4019 rel_size
= Reloc_types
<elfcpp::SHT_RELA
, 64, false>::reloc_size
;
4023 odyn
->add_constant(rel_tag
, rel_size
);
4025 if (parameters
->options().combreloc())
4027 size_t c
= dyn_rel
->relative_reloc_count();
4029 odyn
->add_constant((use_rel
4030 ? elfcpp::DT_RELCOUNT
4031 : elfcpp::DT_RELACOUNT
),
4036 if (add_debug
&& !parameters
->options().shared())
4038 // The value of the DT_DEBUG tag is filled in by the dynamic
4039 // linker at run time, and used by the debugger.
4040 odyn
->add_constant(elfcpp::DT_DEBUG
, 0);
4044 // Finish the .dynamic section and PT_DYNAMIC segment.
4047 Layout::finish_dynamic_section(const Input_objects
* input_objects
,
4048 const Symbol_table
* symtab
)
4050 if (!this->script_options_
->saw_phdrs_clause())
4052 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_DYNAMIC
,
4055 oseg
->add_output_section_to_nonload(this->dynamic_section_
,
4056 elfcpp::PF_R
| elfcpp::PF_W
);
4059 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
4061 for (Input_objects::Dynobj_iterator p
= input_objects
->dynobj_begin();
4062 p
!= input_objects
->dynobj_end();
4065 if (!(*p
)->is_needed() && (*p
)->as_needed())
4067 // This dynamic object was linked with --as-needed, but it
4072 odyn
->add_string(elfcpp::DT_NEEDED
, (*p
)->soname());
4075 if (parameters
->options().shared())
4077 const char* soname
= parameters
->options().soname();
4079 odyn
->add_string(elfcpp::DT_SONAME
, soname
);
4082 Symbol
* sym
= symtab
->lookup(parameters
->options().init());
4083 if (sym
!= NULL
&& sym
->is_defined() && !sym
->is_from_dynobj())
4084 odyn
->add_symbol(elfcpp::DT_INIT
, sym
);
4086 sym
= symtab
->lookup(parameters
->options().fini());
4087 if (sym
!= NULL
&& sym
->is_defined() && !sym
->is_from_dynobj())
4088 odyn
->add_symbol(elfcpp::DT_FINI
, sym
);
4090 // Look for .init_array, .preinit_array and .fini_array by checking
4092 for(Layout::Section_list::const_iterator p
= this->section_list_
.begin();
4093 p
!= this->section_list_
.end();
4095 switch((*p
)->type())
4097 case elfcpp::SHT_FINI_ARRAY
:
4098 odyn
->add_section_address(elfcpp::DT_FINI_ARRAY
, *p
);
4099 odyn
->add_section_size(elfcpp::DT_FINI_ARRAYSZ
, *p
);
4101 case elfcpp::SHT_INIT_ARRAY
:
4102 odyn
->add_section_address(elfcpp::DT_INIT_ARRAY
, *p
);
4103 odyn
->add_section_size(elfcpp::DT_INIT_ARRAYSZ
, *p
);
4105 case elfcpp::SHT_PREINIT_ARRAY
:
4106 odyn
->add_section_address(elfcpp::DT_PREINIT_ARRAY
, *p
);
4107 odyn
->add_section_size(elfcpp::DT_PREINIT_ARRAYSZ
, *p
);
4113 // Add a DT_RPATH entry if needed.
4114 const General_options::Dir_list
& rpath(parameters
->options().rpath());
4117 std::string rpath_val
;
4118 for (General_options::Dir_list::const_iterator p
= rpath
.begin();
4122 if (rpath_val
.empty())
4123 rpath_val
= p
->name();
4126 // Eliminate duplicates.
4127 General_options::Dir_list::const_iterator q
;
4128 for (q
= rpath
.begin(); q
!= p
; ++q
)
4129 if (q
->name() == p
->name())
4134 rpath_val
+= p
->name();
4139 odyn
->add_string(elfcpp::DT_RPATH
, rpath_val
);
4140 if (parameters
->options().enable_new_dtags())
4141 odyn
->add_string(elfcpp::DT_RUNPATH
, rpath_val
);
4144 // Look for text segments that have dynamic relocations.
4145 bool have_textrel
= false;
4146 if (!this->script_options_
->saw_sections_clause())
4148 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
4149 p
!= this->segment_list_
.end();
4152 if ((*p
)->type() == elfcpp::PT_LOAD
4153 && ((*p
)->flags() & elfcpp::PF_W
) == 0
4154 && (*p
)->has_dynamic_reloc())
4156 have_textrel
= true;
4163 // We don't know the section -> segment mapping, so we are
4164 // conservative and just look for readonly sections with
4165 // relocations. If those sections wind up in writable segments,
4166 // then we have created an unnecessary DT_TEXTREL entry.
4167 for (Section_list::const_iterator p
= this->section_list_
.begin();
4168 p
!= this->section_list_
.end();
4171 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) != 0
4172 && ((*p
)->flags() & elfcpp::SHF_WRITE
) == 0
4173 && (*p
)->has_dynamic_reloc())
4175 have_textrel
= true;
4181 // Add a DT_FLAGS entry. We add it even if no flags are set so that
4182 // post-link tools can easily modify these flags if desired.
4183 unsigned int flags
= 0;
4186 // Add a DT_TEXTREL for compatibility with older loaders.
4187 odyn
->add_constant(elfcpp::DT_TEXTREL
, 0);
4188 flags
|= elfcpp::DF_TEXTREL
;
4190 if (parameters
->options().text())
4191 gold_error(_("read-only segment has dynamic relocations"));
4192 else if (parameters
->options().warn_shared_textrel()
4193 && parameters
->options().shared())
4194 gold_warning(_("shared library text segment is not shareable"));
4196 if (parameters
->options().shared() && this->has_static_tls())
4197 flags
|= elfcpp::DF_STATIC_TLS
;
4198 if (parameters
->options().origin())
4199 flags
|= elfcpp::DF_ORIGIN
;
4200 if (parameters
->options().Bsymbolic())
4202 flags
|= elfcpp::DF_SYMBOLIC
;
4203 // Add DT_SYMBOLIC for compatibility with older loaders.
4204 odyn
->add_constant(elfcpp::DT_SYMBOLIC
, 0);
4206 if (parameters
->options().now())
4207 flags
|= elfcpp::DF_BIND_NOW
;
4209 odyn
->add_constant(elfcpp::DT_FLAGS
, flags
);
4212 if (parameters
->options().initfirst())
4213 flags
|= elfcpp::DF_1_INITFIRST
;
4214 if (parameters
->options().interpose())
4215 flags
|= elfcpp::DF_1_INTERPOSE
;
4216 if (parameters
->options().loadfltr())
4217 flags
|= elfcpp::DF_1_LOADFLTR
;
4218 if (parameters
->options().nodefaultlib())
4219 flags
|= elfcpp::DF_1_NODEFLIB
;
4220 if (parameters
->options().nodelete())
4221 flags
|= elfcpp::DF_1_NODELETE
;
4222 if (parameters
->options().nodlopen())
4223 flags
|= elfcpp::DF_1_NOOPEN
;
4224 if (parameters
->options().nodump())
4225 flags
|= elfcpp::DF_1_NODUMP
;
4226 if (!parameters
->options().shared())
4227 flags
&= ~(elfcpp::DF_1_INITFIRST
4228 | elfcpp::DF_1_NODELETE
4229 | elfcpp::DF_1_NOOPEN
);
4230 if (parameters
->options().origin())
4231 flags
|= elfcpp::DF_1_ORIGIN
;
4232 if (parameters
->options().now())
4233 flags
|= elfcpp::DF_1_NOW
;
4235 odyn
->add_constant(elfcpp::DT_FLAGS_1
, flags
);
4238 // Set the size of the _DYNAMIC symbol table to be the size of the
4242 Layout::set_dynamic_symbol_size(const Symbol_table
* symtab
)
4244 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
4245 odyn
->finalize_data_size();
4246 off_t data_size
= odyn
->data_size();
4247 const int size
= parameters
->target().get_size();
4249 symtab
->get_sized_symbol
<32>(this->dynamic_symbol_
)->set_symsize(data_size
);
4250 else if (size
== 64)
4251 symtab
->get_sized_symbol
<64>(this->dynamic_symbol_
)->set_symsize(data_size
);
4256 // The mapping of input section name prefixes to output section names.
4257 // In some cases one prefix is itself a prefix of another prefix; in
4258 // such a case the longer prefix must come first. These prefixes are
4259 // based on the GNU linker default ELF linker script.
4261 #define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 }
4262 const Layout::Section_name_mapping
Layout::section_name_mapping
[] =
4264 MAPPING_INIT(".text.", ".text"),
4265 MAPPING_INIT(".rodata.", ".rodata"),
4266 MAPPING_INIT(".data.rel.ro.local", ".data.rel.ro.local"),
4267 MAPPING_INIT(".data.rel.ro", ".data.rel.ro"),
4268 MAPPING_INIT(".data.", ".data"),
4269 MAPPING_INIT(".bss.", ".bss"),
4270 MAPPING_INIT(".tdata.", ".tdata"),
4271 MAPPING_INIT(".tbss.", ".tbss"),
4272 MAPPING_INIT(".init_array.", ".init_array"),
4273 MAPPING_INIT(".fini_array.", ".fini_array"),
4274 MAPPING_INIT(".sdata.", ".sdata"),
4275 MAPPING_INIT(".sbss.", ".sbss"),
4276 // FIXME: In the GNU linker, .sbss2 and .sdata2 are handled
4277 // differently depending on whether it is creating a shared library.
4278 MAPPING_INIT(".sdata2.", ".sdata"),
4279 MAPPING_INIT(".sbss2.", ".sbss"),
4280 MAPPING_INIT(".lrodata.", ".lrodata"),
4281 MAPPING_INIT(".ldata.", ".ldata"),
4282 MAPPING_INIT(".lbss.", ".lbss"),
4283 MAPPING_INIT(".gcc_except_table.", ".gcc_except_table"),
4284 MAPPING_INIT(".gnu.linkonce.d.rel.ro.local.", ".data.rel.ro.local"),
4285 MAPPING_INIT(".gnu.linkonce.d.rel.ro.", ".data.rel.ro"),
4286 MAPPING_INIT(".gnu.linkonce.t.", ".text"),
4287 MAPPING_INIT(".gnu.linkonce.r.", ".rodata"),
4288 MAPPING_INIT(".gnu.linkonce.d.", ".data"),
4289 MAPPING_INIT(".gnu.linkonce.b.", ".bss"),
4290 MAPPING_INIT(".gnu.linkonce.s.", ".sdata"),
4291 MAPPING_INIT(".gnu.linkonce.sb.", ".sbss"),
4292 MAPPING_INIT(".gnu.linkonce.s2.", ".sdata"),
4293 MAPPING_INIT(".gnu.linkonce.sb2.", ".sbss"),
4294 MAPPING_INIT(".gnu.linkonce.wi.", ".debug_info"),
4295 MAPPING_INIT(".gnu.linkonce.td.", ".tdata"),
4296 MAPPING_INIT(".gnu.linkonce.tb.", ".tbss"),
4297 MAPPING_INIT(".gnu.linkonce.lr.", ".lrodata"),
4298 MAPPING_INIT(".gnu.linkonce.l.", ".ldata"),
4299 MAPPING_INIT(".gnu.linkonce.lb.", ".lbss"),
4300 MAPPING_INIT(".ARM.extab", ".ARM.extab"),
4301 MAPPING_INIT(".gnu.linkonce.armextab.", ".ARM.extab"),
4302 MAPPING_INIT(".ARM.exidx", ".ARM.exidx"),
4303 MAPPING_INIT(".gnu.linkonce.armexidx.", ".ARM.exidx"),
4307 const int Layout::section_name_mapping_count
=
4308 (sizeof(Layout::section_name_mapping
)
4309 / sizeof(Layout::section_name_mapping
[0]));
4311 // Choose the output section name to use given an input section name.
4312 // Set *PLEN to the length of the name. *PLEN is initialized to the
4316 Layout::output_section_name(const Relobj
* relobj
, const char* name
,
4319 // gcc 4.3 generates the following sorts of section names when it
4320 // needs a section name specific to a function:
4326 // .data.rel.local.FN
4328 // .data.rel.ro.local.FN
4335 // The GNU linker maps all of those to the part before the .FN,
4336 // except that .data.rel.local.FN is mapped to .data, and
4337 // .data.rel.ro.local.FN is mapped to .data.rel.ro. The sections
4338 // beginning with .data.rel.ro.local are grouped together.
4340 // For an anonymous namespace, the string FN can contain a '.'.
4342 // Also of interest: .rodata.strN.N, .rodata.cstN, both of which the
4343 // GNU linker maps to .rodata.
4345 // The .data.rel.ro sections are used with -z relro. The sections
4346 // are recognized by name. We use the same names that the GNU
4347 // linker does for these sections.
4349 // It is hard to handle this in a principled way, so we don't even
4350 // try. We use a table of mappings. If the input section name is
4351 // not found in the table, we simply use it as the output section
4354 const Section_name_mapping
* psnm
= section_name_mapping
;
4355 for (int i
= 0; i
< section_name_mapping_count
; ++i
, ++psnm
)
4357 if (strncmp(name
, psnm
->from
, psnm
->fromlen
) == 0)
4359 *plen
= psnm
->tolen
;
4364 // As an additional complication, .ctors sections are output in
4365 // either .ctors or .init_array sections, and .dtors sections are
4366 // output in either .dtors or .fini_array sections.
4367 if (is_prefix_of(".ctors.", name
) || is_prefix_of(".dtors.", name
))
4369 if (parameters
->options().ctors_in_init_array())
4372 return name
[1] == 'c' ? ".init_array" : ".fini_array";
4377 return name
[1] == 'c' ? ".ctors" : ".dtors";
4380 if (parameters
->options().ctors_in_init_array()
4381 && (strcmp(name
, ".ctors") == 0 || strcmp(name
, ".dtors") == 0))
4383 // To make .init_array/.fini_array work with gcc we must exclude
4384 // .ctors and .dtors sections from the crtbegin and crtend
4387 || (!Layout::match_file_name(relobj
, "crtbegin")
4388 && !Layout::match_file_name(relobj
, "crtend")))
4391 return name
[1] == 'c' ? ".init_array" : ".fini_array";
4398 // Return true if RELOBJ is an input file whose base name matches
4399 // FILE_NAME. The base name must have an extension of ".o", and must
4400 // be exactly FILE_NAME.o or FILE_NAME, one character, ".o". This is
4401 // to match crtbegin.o as well as crtbeginS.o without getting confused
4402 // by other possibilities. Overall matching the file name this way is
4403 // a dreadful hack, but the GNU linker does it in order to better
4404 // support gcc, and we need to be compatible.
4407 Layout::match_file_name(const Relobj
* relobj
, const char* match
)
4409 const std::string
& file_name(relobj
->name());
4410 const char* base_name
= lbasename(file_name
.c_str());
4411 size_t match_len
= strlen(match
);
4412 if (strncmp(base_name
, match
, match_len
) != 0)
4414 size_t base_len
= strlen(base_name
);
4415 if (base_len
!= match_len
+ 2 && base_len
!= match_len
+ 3)
4417 return memcmp(base_name
+ base_len
- 2, ".o", 2) == 0;
4420 // Check if a comdat group or .gnu.linkonce section with the given
4421 // NAME is selected for the link. If there is already a section,
4422 // *KEPT_SECTION is set to point to the existing section and the
4423 // function returns false. Otherwise, OBJECT, SHNDX, IS_COMDAT, and
4424 // IS_GROUP_NAME are recorded for this NAME in the layout object,
4425 // *KEPT_SECTION is set to the internal copy and the function returns
4429 Layout::find_or_add_kept_section(const std::string
& name
,
4434 Kept_section
** kept_section
)
4436 // It's normal to see a couple of entries here, for the x86 thunk
4437 // sections. If we see more than a few, we're linking a C++
4438 // program, and we resize to get more space to minimize rehashing.
4439 if (this->signatures_
.size() > 4
4440 && !this->resized_signatures_
)
4442 reserve_unordered_map(&this->signatures_
,
4443 this->number_of_input_files_
* 64);
4444 this->resized_signatures_
= true;
4447 Kept_section candidate
;
4448 std::pair
<Signatures::iterator
, bool> ins
=
4449 this->signatures_
.insert(std::make_pair(name
, candidate
));
4451 if (kept_section
!= NULL
)
4452 *kept_section
= &ins
.first
->second
;
4455 // This is the first time we've seen this signature.
4456 ins
.first
->second
.set_object(object
);
4457 ins
.first
->second
.set_shndx(shndx
);
4459 ins
.first
->second
.set_is_comdat();
4461 ins
.first
->second
.set_is_group_name();
4465 // We have already seen this signature.
4467 if (ins
.first
->second
.is_group_name())
4469 // We've already seen a real section group with this signature.
4470 // If the kept group is from a plugin object, and we're in the
4471 // replacement phase, accept the new one as a replacement.
4472 if (ins
.first
->second
.object() == NULL
4473 && parameters
->options().plugins()->in_replacement_phase())
4475 ins
.first
->second
.set_object(object
);
4476 ins
.first
->second
.set_shndx(shndx
);
4481 else if (is_group_name
)
4483 // This is a real section group, and we've already seen a
4484 // linkonce section with this signature. Record that we've seen
4485 // a section group, and don't include this section group.
4486 ins
.first
->second
.set_is_group_name();
4491 // We've already seen a linkonce section and this is a linkonce
4492 // section. These don't block each other--this may be the same
4493 // symbol name with different section types.
4498 // Store the allocated sections into the section list.
4501 Layout::get_allocated_sections(Section_list
* section_list
) const
4503 for (Section_list::const_iterator p
= this->section_list_
.begin();
4504 p
!= this->section_list_
.end();
4506 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) != 0)
4507 section_list
->push_back(*p
);
4510 // Create an output segment.
4513 Layout::make_output_segment(elfcpp::Elf_Word type
, elfcpp::Elf_Word flags
)
4515 gold_assert(!parameters
->options().relocatable());
4516 Output_segment
* oseg
= new Output_segment(type
, flags
);
4517 this->segment_list_
.push_back(oseg
);
4519 if (type
== elfcpp::PT_TLS
)
4520 this->tls_segment_
= oseg
;
4521 else if (type
== elfcpp::PT_GNU_RELRO
)
4522 this->relro_segment_
= oseg
;
4523 else if (type
== elfcpp::PT_INTERP
)
4524 this->interp_segment_
= oseg
;
4529 // Return the file offset of the normal symbol table.
4532 Layout::symtab_section_offset() const
4534 if (this->symtab_section_
!= NULL
)
4535 return this->symtab_section_
->offset();
4539 // Write out the Output_sections. Most won't have anything to write,
4540 // since most of the data will come from input sections which are
4541 // handled elsewhere. But some Output_sections do have Output_data.
4544 Layout::write_output_sections(Output_file
* of
) const
4546 for (Section_list::const_iterator p
= this->section_list_
.begin();
4547 p
!= this->section_list_
.end();
4550 if (!(*p
)->after_input_sections())
4555 // Write out data not associated with a section or the symbol table.
4558 Layout::write_data(const Symbol_table
* symtab
, Output_file
* of
) const
4560 if (!parameters
->options().strip_all())
4562 const Output_section
* symtab_section
= this->symtab_section_
;
4563 for (Section_list::const_iterator p
= this->section_list_
.begin();
4564 p
!= this->section_list_
.end();
4567 if ((*p
)->needs_symtab_index())
4569 gold_assert(symtab_section
!= NULL
);
4570 unsigned int index
= (*p
)->symtab_index();
4571 gold_assert(index
> 0 && index
!= -1U);
4572 off_t off
= (symtab_section
->offset()
4573 + index
* symtab_section
->entsize());
4574 symtab
->write_section_symbol(*p
, this->symtab_xindex_
, of
, off
);
4579 const Output_section
* dynsym_section
= this->dynsym_section_
;
4580 for (Section_list::const_iterator p
= this->section_list_
.begin();
4581 p
!= this->section_list_
.end();
4584 if ((*p
)->needs_dynsym_index())
4586 gold_assert(dynsym_section
!= NULL
);
4587 unsigned int index
= (*p
)->dynsym_index();
4588 gold_assert(index
> 0 && index
!= -1U);
4589 off_t off
= (dynsym_section
->offset()
4590 + index
* dynsym_section
->entsize());
4591 symtab
->write_section_symbol(*p
, this->dynsym_xindex_
, of
, off
);
4595 // Write out the Output_data which are not in an Output_section.
4596 for (Data_list::const_iterator p
= this->special_output_list_
.begin();
4597 p
!= this->special_output_list_
.end();
4602 // Write out the Output_sections which can only be written after the
4603 // input sections are complete.
4606 Layout::write_sections_after_input_sections(Output_file
* of
)
4608 // Determine the final section offsets, and thus the final output
4609 // file size. Note we finalize the .shstrab last, to allow the
4610 // after_input_section sections to modify their section-names before
4612 if (this->any_postprocessing_sections_
)
4614 off_t off
= this->output_file_size_
;
4615 off
= this->set_section_offsets(off
, POSTPROCESSING_SECTIONS_PASS
);
4617 // Now that we've finalized the names, we can finalize the shstrab.
4619 this->set_section_offsets(off
,
4620 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
);
4622 if (off
> this->output_file_size_
)
4625 this->output_file_size_
= off
;
4629 for (Section_list::const_iterator p
= this->section_list_
.begin();
4630 p
!= this->section_list_
.end();
4633 if ((*p
)->after_input_sections())
4637 this->section_headers_
->write(of
);
4640 // If the build ID requires computing a checksum, do so here, and
4641 // write it out. We compute a checksum over the entire file because
4642 // that is simplest.
4645 Layout::write_build_id(Output_file
* of
) const
4647 if (this->build_id_note_
== NULL
)
4650 const unsigned char* iv
= of
->get_input_view(0, this->output_file_size_
);
4652 unsigned char* ov
= of
->get_output_view(this->build_id_note_
->offset(),
4653 this->build_id_note_
->data_size());
4655 const char* style
= parameters
->options().build_id();
4656 if (strcmp(style
, "sha1") == 0)
4659 sha1_init_ctx(&ctx
);
4660 sha1_process_bytes(iv
, this->output_file_size_
, &ctx
);
4661 sha1_finish_ctx(&ctx
, ov
);
4663 else if (strcmp(style
, "md5") == 0)
4667 md5_process_bytes(iv
, this->output_file_size_
, &ctx
);
4668 md5_finish_ctx(&ctx
, ov
);
4673 of
->write_output_view(this->build_id_note_
->offset(),
4674 this->build_id_note_
->data_size(),
4677 of
->free_input_view(0, this->output_file_size_
, iv
);
4680 // Write out a binary file. This is called after the link is
4681 // complete. IN is the temporary output file we used to generate the
4682 // ELF code. We simply walk through the segments, read them from
4683 // their file offset in IN, and write them to their load address in
4684 // the output file. FIXME: with a bit more work, we could support
4685 // S-records and/or Intel hex format here.
4688 Layout::write_binary(Output_file
* in
) const
4690 gold_assert(parameters
->options().oformat_enum()
4691 == General_options::OBJECT_FORMAT_BINARY
);
4693 // Get the size of the binary file.
4694 uint64_t max_load_address
= 0;
4695 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
4696 p
!= this->segment_list_
.end();
4699 if ((*p
)->type() == elfcpp::PT_LOAD
&& (*p
)->filesz() > 0)
4701 uint64_t max_paddr
= (*p
)->paddr() + (*p
)->filesz();
4702 if (max_paddr
> max_load_address
)
4703 max_load_address
= max_paddr
;
4707 Output_file
out(parameters
->options().output_file_name());
4708 out
.open(max_load_address
);
4710 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
4711 p
!= this->segment_list_
.end();
4714 if ((*p
)->type() == elfcpp::PT_LOAD
&& (*p
)->filesz() > 0)
4716 const unsigned char* vin
= in
->get_input_view((*p
)->offset(),
4718 unsigned char* vout
= out
.get_output_view((*p
)->paddr(),
4720 memcpy(vout
, vin
, (*p
)->filesz());
4721 out
.write_output_view((*p
)->paddr(), (*p
)->filesz(), vout
);
4722 in
->free_input_view((*p
)->offset(), (*p
)->filesz(), vin
);
4729 // Print the output sections to the map file.
4732 Layout::print_to_mapfile(Mapfile
* mapfile
) const
4734 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
4735 p
!= this->segment_list_
.end();
4737 (*p
)->print_sections_to_mapfile(mapfile
);
4740 // Print statistical information to stderr. This is used for --stats.
4743 Layout::print_stats() const
4745 this->namepool_
.print_stats("section name pool");
4746 this->sympool_
.print_stats("output symbol name pool");
4747 this->dynpool_
.print_stats("dynamic name pool");
4749 for (Section_list::const_iterator p
= this->section_list_
.begin();
4750 p
!= this->section_list_
.end();
4752 (*p
)->print_merge_stats();
4755 // Write_sections_task methods.
4757 // We can always run this task.
4760 Write_sections_task::is_runnable()
4765 // We need to unlock both OUTPUT_SECTIONS_BLOCKER and FINAL_BLOCKER
4769 Write_sections_task::locks(Task_locker
* tl
)
4771 tl
->add(this, this->output_sections_blocker_
);
4772 tl
->add(this, this->final_blocker_
);
4775 // Run the task--write out the data.
4778 Write_sections_task::run(Workqueue
*)
4780 this->layout_
->write_output_sections(this->of_
);
4783 // Write_data_task methods.
4785 // We can always run this task.
4788 Write_data_task::is_runnable()
4793 // We need to unlock FINAL_BLOCKER when finished.
4796 Write_data_task::locks(Task_locker
* tl
)
4798 tl
->add(this, this->final_blocker_
);
4801 // Run the task--write out the data.
4804 Write_data_task::run(Workqueue
*)
4806 this->layout_
->write_data(this->symtab_
, this->of_
);
4809 // Write_symbols_task methods.
4811 // We can always run this task.
4814 Write_symbols_task::is_runnable()
4819 // We need to unlock FINAL_BLOCKER when finished.
4822 Write_symbols_task::locks(Task_locker
* tl
)
4824 tl
->add(this, this->final_blocker_
);
4827 // Run the task--write out the symbols.
4830 Write_symbols_task::run(Workqueue
*)
4832 this->symtab_
->write_globals(this->sympool_
, this->dynpool_
,
4833 this->layout_
->symtab_xindex(),
4834 this->layout_
->dynsym_xindex(), this->of_
);
4837 // Write_after_input_sections_task methods.
4839 // We can only run this task after the input sections have completed.
4842 Write_after_input_sections_task::is_runnable()
4844 if (this->input_sections_blocker_
->is_blocked())
4845 return this->input_sections_blocker_
;
4849 // We need to unlock FINAL_BLOCKER when finished.
4852 Write_after_input_sections_task::locks(Task_locker
* tl
)
4854 tl
->add(this, this->final_blocker_
);
4860 Write_after_input_sections_task::run(Workqueue
*)
4862 this->layout_
->write_sections_after_input_sections(this->of_
);
4865 // Close_task_runner methods.
4867 // Run the task--close the file.
4870 Close_task_runner::run(Workqueue
*, const Task
*)
4872 // If we need to compute a checksum for the BUILD if, we do so here.
4873 this->layout_
->write_build_id(this->of_
);
4875 // If we've been asked to create a binary file, we do so here.
4876 if (this->options_
->oformat_enum() != General_options::OBJECT_FORMAT_ELF
)
4877 this->layout_
->write_binary(this->of_
);
4882 // Instantiate the templates we need. We could use the configure
4883 // script to restrict this to only the ones for implemented targets.
4885 #ifdef HAVE_TARGET_32_LITTLE
4888 Layout::init_fixed_output_section
<32, false>(
4890 elfcpp::Shdr
<32, false>& shdr
);
4893 #ifdef HAVE_TARGET_32_BIG
4896 Layout::init_fixed_output_section
<32, true>(
4898 elfcpp::Shdr
<32, true>& shdr
);
4901 #ifdef HAVE_TARGET_64_LITTLE
4904 Layout::init_fixed_output_section
<64, false>(
4906 elfcpp::Shdr
<64, false>& shdr
);
4909 #ifdef HAVE_TARGET_64_BIG
4912 Layout::init_fixed_output_section
<64, true>(
4914 elfcpp::Shdr
<64, true>& shdr
);
4917 #ifdef HAVE_TARGET_32_LITTLE
4920 Layout::layout
<32, false>(Sized_relobj_file
<32, false>* object
,
4923 const elfcpp::Shdr
<32, false>& shdr
,
4924 unsigned int, unsigned int, off_t
*);
4927 #ifdef HAVE_TARGET_32_BIG
4930 Layout::layout
<32, true>(Sized_relobj_file
<32, true>* object
,
4933 const elfcpp::Shdr
<32, true>& shdr
,
4934 unsigned int, unsigned int, off_t
*);
4937 #ifdef HAVE_TARGET_64_LITTLE
4940 Layout::layout
<64, false>(Sized_relobj_file
<64, false>* object
,
4943 const elfcpp::Shdr
<64, false>& shdr
,
4944 unsigned int, unsigned int, off_t
*);
4947 #ifdef HAVE_TARGET_64_BIG
4950 Layout::layout
<64, true>(Sized_relobj_file
<64, true>* object
,
4953 const elfcpp::Shdr
<64, true>& shdr
,
4954 unsigned int, unsigned int, off_t
*);
4957 #ifdef HAVE_TARGET_32_LITTLE
4960 Layout::layout_reloc
<32, false>(Sized_relobj_file
<32, false>* object
,
4961 unsigned int reloc_shndx
,
4962 const elfcpp::Shdr
<32, false>& shdr
,
4963 Output_section
* data_section
,
4964 Relocatable_relocs
* rr
);
4967 #ifdef HAVE_TARGET_32_BIG
4970 Layout::layout_reloc
<32, true>(Sized_relobj_file
<32, true>* object
,
4971 unsigned int reloc_shndx
,
4972 const elfcpp::Shdr
<32, true>& shdr
,
4973 Output_section
* data_section
,
4974 Relocatable_relocs
* rr
);
4977 #ifdef HAVE_TARGET_64_LITTLE
4980 Layout::layout_reloc
<64, false>(Sized_relobj_file
<64, false>* object
,
4981 unsigned int reloc_shndx
,
4982 const elfcpp::Shdr
<64, false>& shdr
,
4983 Output_section
* data_section
,
4984 Relocatable_relocs
* rr
);
4987 #ifdef HAVE_TARGET_64_BIG
4990 Layout::layout_reloc
<64, true>(Sized_relobj_file
<64, true>* object
,
4991 unsigned int reloc_shndx
,
4992 const elfcpp::Shdr
<64, true>& shdr
,
4993 Output_section
* data_section
,
4994 Relocatable_relocs
* rr
);
4997 #ifdef HAVE_TARGET_32_LITTLE
5000 Layout::layout_group
<32, false>(Symbol_table
* symtab
,
5001 Sized_relobj_file
<32, false>* object
,
5003 const char* group_section_name
,
5004 const char* signature
,
5005 const elfcpp::Shdr
<32, false>& shdr
,
5006 elfcpp::Elf_Word flags
,
5007 std::vector
<unsigned int>* shndxes
);
5010 #ifdef HAVE_TARGET_32_BIG
5013 Layout::layout_group
<32, true>(Symbol_table
* symtab
,
5014 Sized_relobj_file
<32, true>* object
,
5016 const char* group_section_name
,
5017 const char* signature
,
5018 const elfcpp::Shdr
<32, true>& shdr
,
5019 elfcpp::Elf_Word flags
,
5020 std::vector
<unsigned int>* shndxes
);
5023 #ifdef HAVE_TARGET_64_LITTLE
5026 Layout::layout_group
<64, false>(Symbol_table
* symtab
,
5027 Sized_relobj_file
<64, false>* object
,
5029 const char* group_section_name
,
5030 const char* signature
,
5031 const elfcpp::Shdr
<64, false>& shdr
,
5032 elfcpp::Elf_Word flags
,
5033 std::vector
<unsigned int>* shndxes
);
5036 #ifdef HAVE_TARGET_64_BIG
5039 Layout::layout_group
<64, true>(Symbol_table
* symtab
,
5040 Sized_relobj_file
<64, true>* object
,
5042 const char* group_section_name
,
5043 const char* signature
,
5044 const elfcpp::Shdr
<64, true>& shdr
,
5045 elfcpp::Elf_Word flags
,
5046 std::vector
<unsigned int>* shndxes
);
5049 #ifdef HAVE_TARGET_32_LITTLE
5052 Layout::layout_eh_frame
<32, false>(Sized_relobj_file
<32, false>* object
,
5053 const unsigned char* symbols
,
5055 const unsigned char* symbol_names
,
5056 off_t symbol_names_size
,
5058 const elfcpp::Shdr
<32, false>& shdr
,
5059 unsigned int reloc_shndx
,
5060 unsigned int reloc_type
,
5064 #ifdef HAVE_TARGET_32_BIG
5067 Layout::layout_eh_frame
<32, true>(Sized_relobj_file
<32, true>* object
,
5068 const unsigned char* symbols
,
5070 const unsigned char* symbol_names
,
5071 off_t symbol_names_size
,
5073 const elfcpp::Shdr
<32, true>& shdr
,
5074 unsigned int reloc_shndx
,
5075 unsigned int reloc_type
,
5079 #ifdef HAVE_TARGET_64_LITTLE
5082 Layout::layout_eh_frame
<64, false>(Sized_relobj_file
<64, false>* object
,
5083 const unsigned char* symbols
,
5085 const unsigned char* symbol_names
,
5086 off_t symbol_names_size
,
5088 const elfcpp::Shdr
<64, false>& shdr
,
5089 unsigned int reloc_shndx
,
5090 unsigned int reloc_type
,
5094 #ifdef HAVE_TARGET_64_BIG
5097 Layout::layout_eh_frame
<64, true>(Sized_relobj_file
<64, true>* object
,
5098 const unsigned char* symbols
,
5100 const unsigned char* symbol_names
,
5101 off_t symbol_names_size
,
5103 const elfcpp::Shdr
<64, true>& shdr
,
5104 unsigned int reloc_shndx
,
5105 unsigned int reloc_type
,
5109 } // End namespace gold.