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 || shdr
.get_sh_type() == elfcpp::SHT_X86_64_UNWIND
);
1137 gold_assert((shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) != 0);
1139 Output_section
* os
= this->make_eh_frame_section(object
);
1143 gold_assert(this->eh_frame_section_
== os
);
1145 elfcpp::Elf_Xword orig_flags
= os
->flags();
1147 if (!parameters
->incremental()
1148 && this->eh_frame_data_
->add_ehframe_input_section(object
,
1157 os
->update_flags_for_input_section(shdr
.get_sh_flags());
1159 // A writable .eh_frame section is a RELRO section.
1160 if ((orig_flags
& (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
))
1161 != (os
->flags() & (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
)))
1164 os
->set_order(ORDER_RELRO
);
1167 // We found a .eh_frame section we are going to optimize, so now
1168 // we can add the set of optimized sections to the output
1169 // section. We need to postpone adding this until we've found a
1170 // section we can optimize so that the .eh_frame section in
1171 // crtbegin.o winds up at the start of the output section.
1172 if (!this->added_eh_frame_data_
)
1174 os
->add_output_section_data(this->eh_frame_data_
);
1175 this->added_eh_frame_data_
= true;
1181 // We couldn't handle this .eh_frame section for some reason.
1182 // Add it as a normal section.
1183 bool saw_sections_clause
= this->script_options_
->saw_sections_clause();
1184 *off
= os
->add_input_section(this, object
, shndx
, ".eh_frame", shdr
,
1185 reloc_shndx
, saw_sections_clause
);
1186 this->have_added_input_section_
= true;
1188 if ((orig_flags
& (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
))
1189 != (os
->flags() & (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
)))
1190 os
->set_order(this->default_section_order(os
, false));
1196 // Create and return the magic .eh_frame section. Create
1197 // .eh_frame_hdr also if appropriate. OBJECT is the object with the
1198 // input .eh_frame section; it may be NULL.
1201 Layout::make_eh_frame_section(const Relobj
* object
)
1203 // FIXME: On x86_64, this could use SHT_X86_64_UNWIND rather than
1205 Output_section
* os
= this->choose_output_section(object
, ".eh_frame",
1206 elfcpp::SHT_PROGBITS
,
1207 elfcpp::SHF_ALLOC
, false,
1208 ORDER_EHFRAME
, false);
1212 if (this->eh_frame_section_
== NULL
)
1214 this->eh_frame_section_
= os
;
1215 this->eh_frame_data_
= new Eh_frame();
1217 // For incremental linking, we do not optimize .eh_frame sections
1218 // or create a .eh_frame_hdr section.
1219 if (parameters
->options().eh_frame_hdr() && !parameters
->incremental())
1221 Output_section
* hdr_os
=
1222 this->choose_output_section(NULL
, ".eh_frame_hdr",
1223 elfcpp::SHT_PROGBITS
,
1224 elfcpp::SHF_ALLOC
, false,
1225 ORDER_EHFRAME
, false);
1229 Eh_frame_hdr
* hdr_posd
= new Eh_frame_hdr(os
,
1230 this->eh_frame_data_
);
1231 hdr_os
->add_output_section_data(hdr_posd
);
1233 hdr_os
->set_after_input_sections();
1235 if (!this->script_options_
->saw_phdrs_clause())
1237 Output_segment
* hdr_oseg
;
1238 hdr_oseg
= this->make_output_segment(elfcpp::PT_GNU_EH_FRAME
,
1240 hdr_oseg
->add_output_section_to_nonload(hdr_os
,
1244 this->eh_frame_data_
->set_eh_frame_hdr(hdr_posd
);
1252 // Add an exception frame for a PLT. This is called from target code.
1255 Layout::add_eh_frame_for_plt(Output_data
* plt
, const unsigned char* cie_data
,
1256 size_t cie_length
, const unsigned char* fde_data
,
1259 if (parameters
->incremental())
1261 // FIXME: Maybe this could work some day....
1264 Output_section
* os
= this->make_eh_frame_section(NULL
);
1267 this->eh_frame_data_
->add_ehframe_for_plt(plt
, cie_data
, cie_length
,
1268 fde_data
, fde_length
);
1269 if (!this->added_eh_frame_data_
)
1271 os
->add_output_section_data(this->eh_frame_data_
);
1272 this->added_eh_frame_data_
= true;
1276 // Add POSD to an output section using NAME, TYPE, and FLAGS. Return
1277 // the output section.
1280 Layout::add_output_section_data(const char* name
, elfcpp::Elf_Word type
,
1281 elfcpp::Elf_Xword flags
,
1282 Output_section_data
* posd
,
1283 Output_section_order order
, bool is_relro
)
1285 Output_section
* os
= this->choose_output_section(NULL
, name
, type
, flags
,
1286 false, order
, is_relro
);
1288 os
->add_output_section_data(posd
);
1292 // Map section flags to segment flags.
1295 Layout::section_flags_to_segment(elfcpp::Elf_Xword flags
)
1297 elfcpp::Elf_Word ret
= elfcpp::PF_R
;
1298 if ((flags
& elfcpp::SHF_WRITE
) != 0)
1299 ret
|= elfcpp::PF_W
;
1300 if ((flags
& elfcpp::SHF_EXECINSTR
) != 0)
1301 ret
|= elfcpp::PF_X
;
1305 // Make a new Output_section, and attach it to segments as
1306 // appropriate. ORDER is the order in which this section should
1307 // appear in the output segment. IS_RELRO is true if this is a relro
1308 // (read-only after relocations) section.
1311 Layout::make_output_section(const char* name
, elfcpp::Elf_Word type
,
1312 elfcpp::Elf_Xword flags
,
1313 Output_section_order order
, bool is_relro
)
1316 if ((flags
& elfcpp::SHF_ALLOC
) == 0
1317 && strcmp(parameters
->options().compress_debug_sections(), "none") != 0
1318 && is_compressible_debug_section(name
))
1319 os
= new Output_compressed_section(¶meters
->options(), name
, type
,
1321 else if ((flags
& elfcpp::SHF_ALLOC
) == 0
1322 && parameters
->options().strip_debug_non_line()
1323 && strcmp(".debug_abbrev", name
) == 0)
1325 os
= this->debug_abbrev_
= new Output_reduced_debug_abbrev_section(
1327 if (this->debug_info_
)
1328 this->debug_info_
->set_abbreviations(this->debug_abbrev_
);
1330 else if ((flags
& elfcpp::SHF_ALLOC
) == 0
1331 && parameters
->options().strip_debug_non_line()
1332 && strcmp(".debug_info", name
) == 0)
1334 os
= this->debug_info_
= new Output_reduced_debug_info_section(
1336 if (this->debug_abbrev_
)
1337 this->debug_info_
->set_abbreviations(this->debug_abbrev_
);
1341 // Sometimes .init_array*, .preinit_array* and .fini_array* do
1342 // not have correct section types. Force them here.
1343 if (type
== elfcpp::SHT_PROGBITS
)
1345 if (is_prefix_of(".init_array", name
))
1346 type
= elfcpp::SHT_INIT_ARRAY
;
1347 else if (is_prefix_of(".preinit_array", name
))
1348 type
= elfcpp::SHT_PREINIT_ARRAY
;
1349 else if (is_prefix_of(".fini_array", name
))
1350 type
= elfcpp::SHT_FINI_ARRAY
;
1353 // FIXME: const_cast is ugly.
1354 Target
* target
= const_cast<Target
*>(¶meters
->target());
1355 os
= target
->make_output_section(name
, type
, flags
);
1358 // With -z relro, we have to recognize the special sections by name.
1359 // There is no other way.
1360 bool is_relro_local
= false;
1361 if (!this->script_options_
->saw_sections_clause()
1362 && parameters
->options().relro()
1363 && type
== elfcpp::SHT_PROGBITS
1364 && (flags
& elfcpp::SHF_ALLOC
) != 0
1365 && (flags
& elfcpp::SHF_WRITE
) != 0)
1367 if (strcmp(name
, ".data.rel.ro") == 0)
1369 else if (strcmp(name
, ".data.rel.ro.local") == 0)
1372 is_relro_local
= true;
1374 else if (type
== elfcpp::SHT_INIT_ARRAY
1375 || type
== elfcpp::SHT_FINI_ARRAY
1376 || type
== elfcpp::SHT_PREINIT_ARRAY
)
1378 else if (strcmp(name
, ".ctors") == 0
1379 || strcmp(name
, ".dtors") == 0
1380 || strcmp(name
, ".jcr") == 0)
1387 if (order
== ORDER_INVALID
&& (flags
& elfcpp::SHF_ALLOC
) != 0)
1388 order
= this->default_section_order(os
, is_relro_local
);
1390 os
->set_order(order
);
1392 parameters
->target().new_output_section(os
);
1394 this->section_list_
.push_back(os
);
1396 // The GNU linker by default sorts some sections by priority, so we
1397 // do the same. We need to know that this might happen before we
1398 // attach any input sections.
1399 if (!this->script_options_
->saw_sections_clause()
1400 && !parameters
->options().relocatable()
1401 && (strcmp(name
, ".init_array") == 0
1402 || strcmp(name
, ".fini_array") == 0
1403 || (!parameters
->options().ctors_in_init_array()
1404 && (strcmp(name
, ".ctors") == 0
1405 || strcmp(name
, ".dtors") == 0))))
1406 os
->set_may_sort_attached_input_sections();
1408 // Check for .stab*str sections, as .stab* sections need to link to
1410 if (type
== elfcpp::SHT_STRTAB
1411 && !this->have_stabstr_section_
1412 && strncmp(name
, ".stab", 5) == 0
1413 && strcmp(name
+ strlen(name
) - 3, "str") == 0)
1414 this->have_stabstr_section_
= true;
1416 // If we have already attached the sections to segments, then we
1417 // need to attach this one now. This happens for sections created
1418 // directly by the linker.
1419 if (this->sections_are_attached_
)
1420 this->attach_section_to_segment(os
);
1425 // Return the default order in which a section should be placed in an
1426 // output segment. This function captures a lot of the ideas in
1427 // ld/scripttempl/elf.sc in the GNU linker. Note that the order of a
1428 // linker created section is normally set when the section is created;
1429 // this function is used for input sections.
1431 Output_section_order
1432 Layout::default_section_order(Output_section
* os
, bool is_relro_local
)
1434 gold_assert((os
->flags() & elfcpp::SHF_ALLOC
) != 0);
1435 bool is_write
= (os
->flags() & elfcpp::SHF_WRITE
) != 0;
1436 bool is_execinstr
= (os
->flags() & elfcpp::SHF_EXECINSTR
) != 0;
1437 bool is_bss
= false;
1442 case elfcpp::SHT_PROGBITS
:
1444 case elfcpp::SHT_NOBITS
:
1447 case elfcpp::SHT_RELA
:
1448 case elfcpp::SHT_REL
:
1450 return ORDER_DYNAMIC_RELOCS
;
1452 case elfcpp::SHT_HASH
:
1453 case elfcpp::SHT_DYNAMIC
:
1454 case elfcpp::SHT_SHLIB
:
1455 case elfcpp::SHT_DYNSYM
:
1456 case elfcpp::SHT_GNU_HASH
:
1457 case elfcpp::SHT_GNU_verdef
:
1458 case elfcpp::SHT_GNU_verneed
:
1459 case elfcpp::SHT_GNU_versym
:
1461 return ORDER_DYNAMIC_LINKER
;
1463 case elfcpp::SHT_NOTE
:
1464 return is_write
? ORDER_RW_NOTE
: ORDER_RO_NOTE
;
1467 if ((os
->flags() & elfcpp::SHF_TLS
) != 0)
1468 return is_bss
? ORDER_TLS_BSS
: ORDER_TLS_DATA
;
1470 if (!is_bss
&& !is_write
)
1474 if (strcmp(os
->name(), ".init") == 0)
1476 else if (strcmp(os
->name(), ".fini") == 0)
1479 return is_execinstr
? ORDER_TEXT
: ORDER_READONLY
;
1483 return is_relro_local
? ORDER_RELRO_LOCAL
: ORDER_RELRO
;
1485 if (os
->is_small_section())
1486 return is_bss
? ORDER_SMALL_BSS
: ORDER_SMALL_DATA
;
1487 if (os
->is_large_section())
1488 return is_bss
? ORDER_LARGE_BSS
: ORDER_LARGE_DATA
;
1490 return is_bss
? ORDER_BSS
: ORDER_DATA
;
1493 // Attach output sections to segments. This is called after we have
1494 // seen all the input sections.
1497 Layout::attach_sections_to_segments()
1499 for (Section_list::iterator p
= this->section_list_
.begin();
1500 p
!= this->section_list_
.end();
1502 this->attach_section_to_segment(*p
);
1504 this->sections_are_attached_
= true;
1507 // Attach an output section to a segment.
1510 Layout::attach_section_to_segment(Output_section
* os
)
1512 if ((os
->flags() & elfcpp::SHF_ALLOC
) == 0)
1513 this->unattached_section_list_
.push_back(os
);
1515 this->attach_allocated_section_to_segment(os
);
1518 // Attach an allocated output section to a segment.
1521 Layout::attach_allocated_section_to_segment(Output_section
* os
)
1523 elfcpp::Elf_Xword flags
= os
->flags();
1524 gold_assert((flags
& elfcpp::SHF_ALLOC
) != 0);
1526 if (parameters
->options().relocatable())
1529 // If we have a SECTIONS clause, we can't handle the attachment to
1530 // segments until after we've seen all the sections.
1531 if (this->script_options_
->saw_sections_clause())
1534 gold_assert(!this->script_options_
->saw_phdrs_clause());
1536 // This output section goes into a PT_LOAD segment.
1538 elfcpp::Elf_Word seg_flags
= Layout::section_flags_to_segment(flags
);
1540 // Check for --section-start.
1542 bool is_address_set
= parameters
->options().section_start(os
->name(), &addr
);
1544 // In general the only thing we really care about for PT_LOAD
1545 // segments is whether or not they are writable or executable,
1546 // so that is how we search for them.
1547 // Large data sections also go into their own PT_LOAD segment.
1548 // People who need segments sorted on some other basis will
1549 // have to use a linker script.
1551 Segment_list::const_iterator p
;
1552 for (p
= this->segment_list_
.begin();
1553 p
!= this->segment_list_
.end();
1556 if ((*p
)->type() != elfcpp::PT_LOAD
)
1558 if (!parameters
->options().omagic()
1559 && ((*p
)->flags() & elfcpp::PF_W
) != (seg_flags
& elfcpp::PF_W
))
1561 if (parameters
->options().rosegment()
1562 && ((*p
)->flags() & elfcpp::PF_X
) != (seg_flags
& elfcpp::PF_X
))
1564 // If -Tbss was specified, we need to separate the data and BSS
1566 if (parameters
->options().user_set_Tbss())
1568 if ((os
->type() == elfcpp::SHT_NOBITS
)
1569 == (*p
)->has_any_data_sections())
1572 if (os
->is_large_data_section() && !(*p
)->is_large_data_segment())
1577 if ((*p
)->are_addresses_set())
1580 (*p
)->add_initial_output_data(os
);
1581 (*p
)->update_flags_for_output_section(seg_flags
);
1582 (*p
)->set_addresses(addr
, addr
);
1586 (*p
)->add_output_section_to_load(this, os
, seg_flags
);
1590 if (p
== this->segment_list_
.end())
1592 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_LOAD
,
1594 if (os
->is_large_data_section())
1595 oseg
->set_is_large_data_segment();
1596 oseg
->add_output_section_to_load(this, os
, seg_flags
);
1598 oseg
->set_addresses(addr
, addr
);
1601 // If we see a loadable SHT_NOTE section, we create a PT_NOTE
1603 if (os
->type() == elfcpp::SHT_NOTE
)
1605 // See if we already have an equivalent PT_NOTE segment.
1606 for (p
= this->segment_list_
.begin();
1607 p
!= segment_list_
.end();
1610 if ((*p
)->type() == elfcpp::PT_NOTE
1611 && (((*p
)->flags() & elfcpp::PF_W
)
1612 == (seg_flags
& elfcpp::PF_W
)))
1614 (*p
)->add_output_section_to_nonload(os
, seg_flags
);
1619 if (p
== this->segment_list_
.end())
1621 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_NOTE
,
1623 oseg
->add_output_section_to_nonload(os
, seg_flags
);
1627 // If we see a loadable SHF_TLS section, we create a PT_TLS
1628 // segment. There can only be one such segment.
1629 if ((flags
& elfcpp::SHF_TLS
) != 0)
1631 if (this->tls_segment_
== NULL
)
1632 this->make_output_segment(elfcpp::PT_TLS
, seg_flags
);
1633 this->tls_segment_
->add_output_section_to_nonload(os
, seg_flags
);
1636 // If -z relro is in effect, and we see a relro section, we create a
1637 // PT_GNU_RELRO segment. There can only be one such segment.
1638 if (os
->is_relro() && parameters
->options().relro())
1640 gold_assert(seg_flags
== (elfcpp::PF_R
| elfcpp::PF_W
));
1641 if (this->relro_segment_
== NULL
)
1642 this->make_output_segment(elfcpp::PT_GNU_RELRO
, seg_flags
);
1643 this->relro_segment_
->add_output_section_to_nonload(os
, seg_flags
);
1646 // If we see a section named .interp, put it into a PT_INTERP
1647 // segment. This seems broken to me, but this is what GNU ld does,
1648 // and glibc expects it.
1649 if (strcmp(os
->name(), ".interp") == 0
1650 && !this->script_options_
->saw_phdrs_clause())
1652 if (this->interp_segment_
== NULL
)
1653 this->make_output_segment(elfcpp::PT_INTERP
, seg_flags
);
1655 gold_warning(_("multiple '.interp' sections in input files "
1656 "may cause confusing PT_INTERP segment"));
1657 this->interp_segment_
->add_output_section_to_nonload(os
, seg_flags
);
1661 // Make an output section for a script.
1664 Layout::make_output_section_for_script(
1666 Script_sections::Section_type section_type
)
1668 name
= this->namepool_
.add(name
, false, NULL
);
1669 elfcpp::Elf_Xword sh_flags
= elfcpp::SHF_ALLOC
;
1670 if (section_type
== Script_sections::ST_NOLOAD
)
1672 Output_section
* os
= this->make_output_section(name
, elfcpp::SHT_PROGBITS
,
1673 sh_flags
, ORDER_INVALID
,
1675 os
->set_found_in_sections_clause();
1676 if (section_type
== Script_sections::ST_NOLOAD
)
1677 os
->set_is_noload();
1681 // Return the number of segments we expect to see.
1684 Layout::expected_segment_count() const
1686 size_t ret
= this->segment_list_
.size();
1688 // If we didn't see a SECTIONS clause in a linker script, we should
1689 // already have the complete list of segments. Otherwise we ask the
1690 // SECTIONS clause how many segments it expects, and add in the ones
1691 // we already have (PT_GNU_STACK, PT_GNU_EH_FRAME, etc.)
1693 if (!this->script_options_
->saw_sections_clause())
1697 const Script_sections
* ss
= this->script_options_
->script_sections();
1698 return ret
+ ss
->expected_segment_count(this);
1702 // Handle the .note.GNU-stack section at layout time. SEEN_GNU_STACK
1703 // is whether we saw a .note.GNU-stack section in the object file.
1704 // GNU_STACK_FLAGS is the section flags. The flags give the
1705 // protection required for stack memory. We record this in an
1706 // executable as a PT_GNU_STACK segment. If an object file does not
1707 // have a .note.GNU-stack segment, we must assume that it is an old
1708 // object. On some targets that will force an executable stack.
1711 Layout::layout_gnu_stack(bool seen_gnu_stack
, uint64_t gnu_stack_flags
,
1714 if (!seen_gnu_stack
)
1716 this->input_without_gnu_stack_note_
= true;
1717 if (parameters
->options().warn_execstack()
1718 && parameters
->target().is_default_stack_executable())
1719 gold_warning(_("%s: missing .note.GNU-stack section"
1720 " implies executable stack"),
1721 obj
->name().c_str());
1725 this->input_with_gnu_stack_note_
= true;
1726 if ((gnu_stack_flags
& elfcpp::SHF_EXECINSTR
) != 0)
1728 this->input_requires_executable_stack_
= true;
1729 if (parameters
->options().warn_execstack()
1730 || parameters
->options().is_stack_executable())
1731 gold_warning(_("%s: requires executable stack"),
1732 obj
->name().c_str());
1737 // Create automatic note sections.
1740 Layout::create_notes()
1742 this->create_gold_note();
1743 this->create_executable_stack_info();
1744 this->create_build_id();
1747 // Create the dynamic sections which are needed before we read the
1751 Layout::create_initial_dynamic_sections(Symbol_table
* symtab
)
1753 if (parameters
->doing_static_link())
1756 this->dynamic_section_
= this->choose_output_section(NULL
, ".dynamic",
1757 elfcpp::SHT_DYNAMIC
,
1759 | elfcpp::SHF_WRITE
),
1763 this->dynamic_symbol_
=
1764 symtab
->define_in_output_data("_DYNAMIC", NULL
, Symbol_table::PREDEFINED
,
1765 this->dynamic_section_
, 0, 0,
1766 elfcpp::STT_OBJECT
, elfcpp::STB_LOCAL
,
1767 elfcpp::STV_HIDDEN
, 0, false, false);
1769 this->dynamic_data_
= new Output_data_dynamic(&this->dynpool_
);
1771 this->dynamic_section_
->add_output_section_data(this->dynamic_data_
);
1774 // For each output section whose name can be represented as C symbol,
1775 // define __start and __stop symbols for the section. This is a GNU
1779 Layout::define_section_symbols(Symbol_table
* symtab
)
1781 for (Section_list::const_iterator p
= this->section_list_
.begin();
1782 p
!= this->section_list_
.end();
1785 const char* const name
= (*p
)->name();
1786 if (is_cident(name
))
1788 const std::string
name_string(name
);
1789 const std::string
start_name(cident_section_start_prefix
1791 const std::string
stop_name(cident_section_stop_prefix
1794 symtab
->define_in_output_data(start_name
.c_str(),
1796 Symbol_table::PREDEFINED
,
1802 elfcpp::STV_DEFAULT
,
1804 false, // offset_is_from_end
1805 true); // only_if_ref
1807 symtab
->define_in_output_data(stop_name
.c_str(),
1809 Symbol_table::PREDEFINED
,
1815 elfcpp::STV_DEFAULT
,
1817 true, // offset_is_from_end
1818 true); // only_if_ref
1823 // Define symbols for group signatures.
1826 Layout::define_group_signatures(Symbol_table
* symtab
)
1828 for (Group_signatures::iterator p
= this->group_signatures_
.begin();
1829 p
!= this->group_signatures_
.end();
1832 Symbol
* sym
= symtab
->lookup(p
->signature
, NULL
);
1834 p
->section
->set_info_symndx(sym
);
1837 // Force the name of the group section to the group
1838 // signature, and use the group's section symbol as the
1839 // signature symbol.
1840 if (strcmp(p
->section
->name(), p
->signature
) != 0)
1842 const char* name
= this->namepool_
.add(p
->signature
,
1844 p
->section
->set_name(name
);
1846 p
->section
->set_needs_symtab_index();
1847 p
->section
->set_info_section_symndx(p
->section
);
1851 this->group_signatures_
.clear();
1854 // Find the first read-only PT_LOAD segment, creating one if
1858 Layout::find_first_load_seg()
1860 Output_segment
* best
= NULL
;
1861 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
1862 p
!= this->segment_list_
.end();
1865 if ((*p
)->type() == elfcpp::PT_LOAD
1866 && ((*p
)->flags() & elfcpp::PF_R
) != 0
1867 && (parameters
->options().omagic()
1868 || ((*p
)->flags() & elfcpp::PF_W
) == 0))
1870 if (best
== NULL
|| this->segment_precedes(*p
, best
))
1877 gold_assert(!this->script_options_
->saw_phdrs_clause());
1879 Output_segment
* load_seg
= this->make_output_segment(elfcpp::PT_LOAD
,
1884 // Save states of all current output segments. Store saved states
1885 // in SEGMENT_STATES.
1888 Layout::save_segments(Segment_states
* segment_states
)
1890 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
1891 p
!= this->segment_list_
.end();
1894 Output_segment
* segment
= *p
;
1896 Output_segment
* copy
= new Output_segment(*segment
);
1897 (*segment_states
)[segment
] = copy
;
1901 // Restore states of output segments and delete any segment not found in
1905 Layout::restore_segments(const Segment_states
* segment_states
)
1907 // Go through the segment list and remove any segment added in the
1909 this->tls_segment_
= NULL
;
1910 this->relro_segment_
= NULL
;
1911 Segment_list::iterator list_iter
= this->segment_list_
.begin();
1912 while (list_iter
!= this->segment_list_
.end())
1914 Output_segment
* segment
= *list_iter
;
1915 Segment_states::const_iterator states_iter
=
1916 segment_states
->find(segment
);
1917 if (states_iter
!= segment_states
->end())
1919 const Output_segment
* copy
= states_iter
->second
;
1920 // Shallow copy to restore states.
1923 // Also fix up TLS and RELRO segment pointers as appropriate.
1924 if (segment
->type() == elfcpp::PT_TLS
)
1925 this->tls_segment_
= segment
;
1926 else if (segment
->type() == elfcpp::PT_GNU_RELRO
)
1927 this->relro_segment_
= segment
;
1933 list_iter
= this->segment_list_
.erase(list_iter
);
1934 // This is a segment created during section layout. It should be
1935 // safe to remove it since we should have removed all pointers to it.
1941 // Clean up after relaxation so that sections can be laid out again.
1944 Layout::clean_up_after_relaxation()
1946 // Restore the segments to point state just prior to the relaxation loop.
1947 Script_sections
* script_section
= this->script_options_
->script_sections();
1948 script_section
->release_segments();
1949 this->restore_segments(this->segment_states_
);
1951 // Reset section addresses and file offsets
1952 for (Section_list::iterator p
= this->section_list_
.begin();
1953 p
!= this->section_list_
.end();
1956 (*p
)->restore_states();
1958 // If an input section changes size because of relaxation,
1959 // we need to adjust the section offsets of all input sections.
1960 // after such a section.
1961 if ((*p
)->section_offsets_need_adjustment())
1962 (*p
)->adjust_section_offsets();
1964 (*p
)->reset_address_and_file_offset();
1967 // Reset special output object address and file offsets.
1968 for (Data_list::iterator p
= this->special_output_list_
.begin();
1969 p
!= this->special_output_list_
.end();
1971 (*p
)->reset_address_and_file_offset();
1973 // A linker script may have created some output section data objects.
1974 // They are useless now.
1975 for (Output_section_data_list::const_iterator p
=
1976 this->script_output_section_data_list_
.begin();
1977 p
!= this->script_output_section_data_list_
.end();
1980 this->script_output_section_data_list_
.clear();
1983 // Prepare for relaxation.
1986 Layout::prepare_for_relaxation()
1988 // Create an relaxation debug check if in debugging mode.
1989 if (is_debugging_enabled(DEBUG_RELAXATION
))
1990 this->relaxation_debug_check_
= new Relaxation_debug_check();
1992 // Save segment states.
1993 this->segment_states_
= new Segment_states();
1994 this->save_segments(this->segment_states_
);
1996 for(Section_list::const_iterator p
= this->section_list_
.begin();
1997 p
!= this->section_list_
.end();
1999 (*p
)->save_states();
2001 if (is_debugging_enabled(DEBUG_RELAXATION
))
2002 this->relaxation_debug_check_
->check_output_data_for_reset_values(
2003 this->section_list_
, this->special_output_list_
);
2005 // Also enable recording of output section data from scripts.
2006 this->record_output_section_data_from_script_
= true;
2009 // Relaxation loop body: If target has no relaxation, this runs only once
2010 // Otherwise, the target relaxation hook is called at the end of
2011 // each iteration. If the hook returns true, it means re-layout of
2012 // section is required.
2014 // The number of segments created by a linking script without a PHDRS
2015 // clause may be affected by section sizes and alignments. There is
2016 // a remote chance that relaxation causes different number of PT_LOAD
2017 // segments are created and sections are attached to different segments.
2018 // Therefore, we always throw away all segments created during section
2019 // layout. In order to be able to restart the section layout, we keep
2020 // a copy of the segment list right before the relaxation loop and use
2021 // that to restore the segments.
2023 // PASS is the current relaxation pass number.
2024 // SYMTAB is a symbol table.
2025 // PLOAD_SEG is the address of a pointer for the load segment.
2026 // PHDR_SEG is a pointer to the PHDR segment.
2027 // SEGMENT_HEADERS points to the output segment header.
2028 // FILE_HEADER points to the output file header.
2029 // PSHNDX is the address to store the output section index.
2032 Layout::relaxation_loop_body(
2035 Symbol_table
* symtab
,
2036 Output_segment
** pload_seg
,
2037 Output_segment
* phdr_seg
,
2038 Output_segment_headers
* segment_headers
,
2039 Output_file_header
* file_header
,
2040 unsigned int* pshndx
)
2042 // If this is not the first iteration, we need to clean up after
2043 // relaxation so that we can lay out the sections again.
2045 this->clean_up_after_relaxation();
2047 // If there is a SECTIONS clause, put all the input sections into
2048 // the required order.
2049 Output_segment
* load_seg
;
2050 if (this->script_options_
->saw_sections_clause())
2051 load_seg
= this->set_section_addresses_from_script(symtab
);
2052 else if (parameters
->options().relocatable())
2055 load_seg
= this->find_first_load_seg();
2057 if (parameters
->options().oformat_enum()
2058 != General_options::OBJECT_FORMAT_ELF
)
2061 // If the user set the address of the text segment, that may not be
2062 // compatible with putting the segment headers and file headers into
2064 if (parameters
->options().user_set_Ttext())
2067 gold_assert(phdr_seg
== NULL
2069 || this->script_options_
->saw_sections_clause());
2071 // If the address of the load segment we found has been set by
2072 // --section-start rather than by a script, then adjust the VMA and
2073 // LMA downward if possible to include the file and section headers.
2074 uint64_t header_gap
= 0;
2075 if (load_seg
!= NULL
2076 && load_seg
->are_addresses_set()
2077 && !this->script_options_
->saw_sections_clause()
2078 && !parameters
->options().relocatable())
2080 file_header
->finalize_data_size();
2081 segment_headers
->finalize_data_size();
2082 size_t sizeof_headers
= (file_header
->data_size()
2083 + segment_headers
->data_size());
2084 const uint64_t abi_pagesize
= target
->abi_pagesize();
2085 uint64_t hdr_paddr
= load_seg
->paddr() - sizeof_headers
;
2086 hdr_paddr
&= ~(abi_pagesize
- 1);
2087 uint64_t subtract
= load_seg
->paddr() - hdr_paddr
;
2088 if (load_seg
->paddr() < subtract
|| load_seg
->vaddr() < subtract
)
2092 load_seg
->set_addresses(load_seg
->vaddr() - subtract
,
2093 load_seg
->paddr() - subtract
);
2094 header_gap
= subtract
- sizeof_headers
;
2098 // Lay out the segment headers.
2099 if (!parameters
->options().relocatable())
2101 gold_assert(segment_headers
!= NULL
);
2102 if (header_gap
!= 0 && load_seg
!= NULL
)
2104 Output_data_zero_fill
* z
= new Output_data_zero_fill(header_gap
, 1);
2105 load_seg
->add_initial_output_data(z
);
2107 if (load_seg
!= NULL
)
2108 load_seg
->add_initial_output_data(segment_headers
);
2109 if (phdr_seg
!= NULL
)
2110 phdr_seg
->add_initial_output_data(segment_headers
);
2113 // Lay out the file header.
2114 if (load_seg
!= NULL
)
2115 load_seg
->add_initial_output_data(file_header
);
2117 if (this->script_options_
->saw_phdrs_clause()
2118 && !parameters
->options().relocatable())
2120 // Support use of FILEHDRS and PHDRS attachments in a PHDRS
2121 // clause in a linker script.
2122 Script_sections
* ss
= this->script_options_
->script_sections();
2123 ss
->put_headers_in_phdrs(file_header
, segment_headers
);
2126 // We set the output section indexes in set_segment_offsets and
2127 // set_section_indexes.
2130 // Set the file offsets of all the segments, and all the sections
2133 if (!parameters
->options().relocatable())
2134 off
= this->set_segment_offsets(target
, load_seg
, pshndx
);
2136 off
= this->set_relocatable_section_offsets(file_header
, pshndx
);
2138 // Verify that the dummy relaxation does not change anything.
2139 if (is_debugging_enabled(DEBUG_RELAXATION
))
2142 this->relaxation_debug_check_
->read_sections(this->section_list_
);
2144 this->relaxation_debug_check_
->verify_sections(this->section_list_
);
2147 *pload_seg
= load_seg
;
2151 // Search the list of patterns and find the postion of the given section
2152 // name in the output section. If the section name matches a glob
2153 // pattern and a non-glob name, then the non-glob position takes
2154 // precedence. Return 0 if no match is found.
2157 Layout::find_section_order_index(const std::string
& section_name
)
2159 Unordered_map
<std::string
, unsigned int>::iterator map_it
;
2160 map_it
= this->input_section_position_
.find(section_name
);
2161 if (map_it
!= this->input_section_position_
.end())
2162 return map_it
->second
;
2164 // Absolute match failed. Linear search the glob patterns.
2165 std::vector
<std::string
>::iterator it
;
2166 for (it
= this->input_section_glob_
.begin();
2167 it
!= this->input_section_glob_
.end();
2170 if (fnmatch((*it
).c_str(), section_name
.c_str(), FNM_NOESCAPE
) == 0)
2172 map_it
= this->input_section_position_
.find(*it
);
2173 gold_assert(map_it
!= this->input_section_position_
.end());
2174 return map_it
->second
;
2180 // Read the sequence of input sections from the file specified with
2181 // --section-ordering-file.
2184 Layout::read_layout_from_file()
2186 const char* filename
= parameters
->options().section_ordering_file();
2192 gold_fatal(_("unable to open --section-ordering-file file %s: %s"),
2193 filename
, strerror(errno
));
2195 std::getline(in
, line
); // this chops off the trailing \n, if any
2196 unsigned int position
= 1;
2200 if (!line
.empty() && line
[line
.length() - 1] == '\r') // Windows
2201 line
.resize(line
.length() - 1);
2202 // Ignore comments, beginning with '#'
2205 std::getline(in
, line
);
2208 this->input_section_position_
[line
] = position
;
2209 // Store all glob patterns in a vector.
2210 if (is_wildcard_string(line
.c_str()))
2211 this->input_section_glob_
.push_back(line
);
2213 std::getline(in
, line
);
2217 // Finalize the layout. When this is called, we have created all the
2218 // output sections and all the output segments which are based on
2219 // input sections. We have several things to do, and we have to do
2220 // them in the right order, so that we get the right results correctly
2223 // 1) Finalize the list of output segments and create the segment
2226 // 2) Finalize the dynamic symbol table and associated sections.
2228 // 3) Determine the final file offset of all the output segments.
2230 // 4) Determine the final file offset of all the SHF_ALLOC output
2233 // 5) Create the symbol table sections and the section name table
2236 // 6) Finalize the symbol table: set symbol values to their final
2237 // value and make a final determination of which symbols are going
2238 // into the output symbol table.
2240 // 7) Create the section table header.
2242 // 8) Determine the final file offset of all the output sections which
2243 // are not SHF_ALLOC, including the section table header.
2245 // 9) Finalize the ELF file header.
2247 // This function returns the size of the output file.
2250 Layout::finalize(const Input_objects
* input_objects
, Symbol_table
* symtab
,
2251 Target
* target
, const Task
* task
)
2253 target
->finalize_sections(this, input_objects
, symtab
);
2255 this->count_local_symbols(task
, input_objects
);
2257 this->link_stabs_sections();
2259 Output_segment
* phdr_seg
= NULL
;
2260 if (!parameters
->options().relocatable() && !parameters
->doing_static_link())
2262 // There was a dynamic object in the link. We need to create
2263 // some information for the dynamic linker.
2265 // Create the PT_PHDR segment which will hold the program
2267 if (!this->script_options_
->saw_phdrs_clause())
2268 phdr_seg
= this->make_output_segment(elfcpp::PT_PHDR
, elfcpp::PF_R
);
2270 // Create the dynamic symbol table, including the hash table.
2271 Output_section
* dynstr
;
2272 std::vector
<Symbol
*> dynamic_symbols
;
2273 unsigned int local_dynamic_count
;
2274 Versions
versions(*this->script_options()->version_script_info(),
2276 this->create_dynamic_symtab(input_objects
, symtab
, &dynstr
,
2277 &local_dynamic_count
, &dynamic_symbols
,
2280 // Create the .interp section to hold the name of the
2281 // interpreter, and put it in a PT_INTERP segment. Don't do it
2282 // if we saw a .interp section in an input file.
2283 if ((!parameters
->options().shared()
2284 || parameters
->options().dynamic_linker() != NULL
)
2285 && this->interp_segment_
== NULL
)
2286 this->create_interp(target
);
2288 // Finish the .dynamic section to hold the dynamic data, and put
2289 // it in a PT_DYNAMIC segment.
2290 this->finish_dynamic_section(input_objects
, symtab
);
2292 // We should have added everything we need to the dynamic string
2294 this->dynpool_
.set_string_offsets();
2296 // Create the version sections. We can't do this until the
2297 // dynamic string table is complete.
2298 this->create_version_sections(&versions
, symtab
, local_dynamic_count
,
2299 dynamic_symbols
, dynstr
);
2301 // Set the size of the _DYNAMIC symbol. We can't do this until
2302 // after we call create_version_sections.
2303 this->set_dynamic_symbol_size(symtab
);
2306 // Create segment headers.
2307 Output_segment_headers
* segment_headers
=
2308 (parameters
->options().relocatable()
2310 : new Output_segment_headers(this->segment_list_
));
2312 // Lay out the file header.
2313 Output_file_header
* file_header
= new Output_file_header(target
, symtab
,
2316 this->special_output_list_
.push_back(file_header
);
2317 if (segment_headers
!= NULL
)
2318 this->special_output_list_
.push_back(segment_headers
);
2320 // Find approriate places for orphan output sections if we are using
2322 if (this->script_options_
->saw_sections_clause())
2323 this->place_orphan_sections_in_script();
2325 Output_segment
* load_seg
;
2330 // Take a snapshot of the section layout as needed.
2331 if (target
->may_relax())
2332 this->prepare_for_relaxation();
2334 // Run the relaxation loop to lay out sections.
2337 off
= this->relaxation_loop_body(pass
, target
, symtab
, &load_seg
,
2338 phdr_seg
, segment_headers
, file_header
,
2342 while (target
->may_relax()
2343 && target
->relax(pass
, input_objects
, symtab
, this, task
));
2345 // Set the file offsets of all the non-data sections we've seen so
2346 // far which don't have to wait for the input sections. We need
2347 // this in order to finalize local symbols in non-allocated
2349 off
= this->set_section_offsets(off
, BEFORE_INPUT_SECTIONS_PASS
);
2351 // Set the section indexes of all unallocated sections seen so far,
2352 // in case any of them are somehow referenced by a symbol.
2353 shndx
= this->set_section_indexes(shndx
);
2355 // Create the symbol table sections.
2356 this->create_symtab_sections(input_objects
, symtab
, shndx
, &off
);
2357 if (!parameters
->doing_static_link())
2358 this->assign_local_dynsym_offsets(input_objects
);
2360 // Process any symbol assignments from a linker script. This must
2361 // be called after the symbol table has been finalized.
2362 this->script_options_
->finalize_symbols(symtab
, this);
2364 // Create the incremental inputs sections.
2365 if (this->incremental_inputs_
)
2367 this->incremental_inputs_
->finalize();
2368 this->create_incremental_info_sections(symtab
);
2371 // Create the .shstrtab section.
2372 Output_section
* shstrtab_section
= this->create_shstrtab();
2374 // Set the file offsets of the rest of the non-data sections which
2375 // don't have to wait for the input sections.
2376 off
= this->set_section_offsets(off
, BEFORE_INPUT_SECTIONS_PASS
);
2378 // Now that all sections have been created, set the section indexes
2379 // for any sections which haven't been done yet.
2380 shndx
= this->set_section_indexes(shndx
);
2382 // Create the section table header.
2383 this->create_shdrs(shstrtab_section
, &off
);
2385 // If there are no sections which require postprocessing, we can
2386 // handle the section names now, and avoid a resize later.
2387 if (!this->any_postprocessing_sections_
)
2389 off
= this->set_section_offsets(off
,
2390 POSTPROCESSING_SECTIONS_PASS
);
2392 this->set_section_offsets(off
,
2393 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
);
2396 file_header
->set_section_info(this->section_headers_
, shstrtab_section
);
2398 // Now we know exactly where everything goes in the output file
2399 // (except for non-allocated sections which require postprocessing).
2400 Output_data::layout_complete();
2402 this->output_file_size_
= off
;
2407 // Create a note header following the format defined in the ELF ABI.
2408 // NAME is the name, NOTE_TYPE is the type, SECTION_NAME is the name
2409 // of the section to create, DESCSZ is the size of the descriptor.
2410 // ALLOCATE is true if the section should be allocated in memory.
2411 // This returns the new note section. It sets *TRAILING_PADDING to
2412 // the number of trailing zero bytes required.
2415 Layout::create_note(const char* name
, int note_type
,
2416 const char* section_name
, size_t descsz
,
2417 bool allocate
, size_t* trailing_padding
)
2419 // Authorities all agree that the values in a .note field should
2420 // be aligned on 4-byte boundaries for 32-bit binaries. However,
2421 // they differ on what the alignment is for 64-bit binaries.
2422 // The GABI says unambiguously they take 8-byte alignment:
2423 // http://sco.com/developers/gabi/latest/ch5.pheader.html#note_section
2424 // Other documentation says alignment should always be 4 bytes:
2425 // http://www.netbsd.org/docs/kernel/elf-notes.html#note-format
2426 // GNU ld and GNU readelf both support the latter (at least as of
2427 // version 2.16.91), and glibc always generates the latter for
2428 // .note.ABI-tag (as of version 1.6), so that's the one we go with
2430 #ifdef GABI_FORMAT_FOR_DOTNOTE_SECTION // This is not defined by default.
2431 const int size
= parameters
->target().get_size();
2433 const int size
= 32;
2436 // The contents of the .note section.
2437 size_t namesz
= strlen(name
) + 1;
2438 size_t aligned_namesz
= align_address(namesz
, size
/ 8);
2439 size_t aligned_descsz
= align_address(descsz
, size
/ 8);
2441 size_t notehdrsz
= 3 * (size
/ 8) + aligned_namesz
;
2443 unsigned char* buffer
= new unsigned char[notehdrsz
];
2444 memset(buffer
, 0, notehdrsz
);
2446 bool is_big_endian
= parameters
->target().is_big_endian();
2452 elfcpp::Swap
<32, false>::writeval(buffer
, namesz
);
2453 elfcpp::Swap
<32, false>::writeval(buffer
+ 4, descsz
);
2454 elfcpp::Swap
<32, false>::writeval(buffer
+ 8, note_type
);
2458 elfcpp::Swap
<32, true>::writeval(buffer
, namesz
);
2459 elfcpp::Swap
<32, true>::writeval(buffer
+ 4, descsz
);
2460 elfcpp::Swap
<32, true>::writeval(buffer
+ 8, note_type
);
2463 else if (size
== 64)
2467 elfcpp::Swap
<64, false>::writeval(buffer
, namesz
);
2468 elfcpp::Swap
<64, false>::writeval(buffer
+ 8, descsz
);
2469 elfcpp::Swap
<64, false>::writeval(buffer
+ 16, note_type
);
2473 elfcpp::Swap
<64, true>::writeval(buffer
, namesz
);
2474 elfcpp::Swap
<64, true>::writeval(buffer
+ 8, descsz
);
2475 elfcpp::Swap
<64, true>::writeval(buffer
+ 16, note_type
);
2481 memcpy(buffer
+ 3 * (size
/ 8), name
, namesz
);
2483 elfcpp::Elf_Xword flags
= 0;
2484 Output_section_order order
= ORDER_INVALID
;
2487 flags
= elfcpp::SHF_ALLOC
;
2488 order
= ORDER_RO_NOTE
;
2490 Output_section
* os
= this->choose_output_section(NULL
, section_name
,
2492 flags
, false, order
, false);
2496 Output_section_data
* posd
= new Output_data_const_buffer(buffer
, notehdrsz
,
2499 os
->add_output_section_data(posd
);
2501 *trailing_padding
= aligned_descsz
- descsz
;
2506 // For an executable or shared library, create a note to record the
2507 // version of gold used to create the binary.
2510 Layout::create_gold_note()
2512 if (parameters
->options().relocatable()
2513 || parameters
->incremental_update())
2516 std::string desc
= std::string("gold ") + gold::get_version_string();
2518 size_t trailing_padding
;
2519 Output_section
* os
= this->create_note("GNU", elfcpp::NT_GNU_GOLD_VERSION
,
2520 ".note.gnu.gold-version", desc
.size(),
2521 false, &trailing_padding
);
2525 Output_section_data
* posd
= new Output_data_const(desc
, 4);
2526 os
->add_output_section_data(posd
);
2528 if (trailing_padding
> 0)
2530 posd
= new Output_data_zero_fill(trailing_padding
, 0);
2531 os
->add_output_section_data(posd
);
2535 // Record whether the stack should be executable. This can be set
2536 // from the command line using the -z execstack or -z noexecstack
2537 // options. Otherwise, if any input file has a .note.GNU-stack
2538 // section with the SHF_EXECINSTR flag set, the stack should be
2539 // executable. Otherwise, if at least one input file a
2540 // .note.GNU-stack section, and some input file has no .note.GNU-stack
2541 // section, we use the target default for whether the stack should be
2542 // executable. Otherwise, we don't generate a stack note. When
2543 // generating a object file, we create a .note.GNU-stack section with
2544 // the appropriate marking. When generating an executable or shared
2545 // library, we create a PT_GNU_STACK segment.
2548 Layout::create_executable_stack_info()
2550 bool is_stack_executable
;
2551 if (parameters
->options().is_execstack_set())
2552 is_stack_executable
= parameters
->options().is_stack_executable();
2553 else if (!this->input_with_gnu_stack_note_
)
2557 if (this->input_requires_executable_stack_
)
2558 is_stack_executable
= true;
2559 else if (this->input_without_gnu_stack_note_
)
2560 is_stack_executable
=
2561 parameters
->target().is_default_stack_executable();
2563 is_stack_executable
= false;
2566 if (parameters
->options().relocatable())
2568 const char* name
= this->namepool_
.add(".note.GNU-stack", false, NULL
);
2569 elfcpp::Elf_Xword flags
= 0;
2570 if (is_stack_executable
)
2571 flags
|= elfcpp::SHF_EXECINSTR
;
2572 this->make_output_section(name
, elfcpp::SHT_PROGBITS
, flags
,
2573 ORDER_INVALID
, false);
2577 if (this->script_options_
->saw_phdrs_clause())
2579 int flags
= elfcpp::PF_R
| elfcpp::PF_W
;
2580 if (is_stack_executable
)
2581 flags
|= elfcpp::PF_X
;
2582 this->make_output_segment(elfcpp::PT_GNU_STACK
, flags
);
2586 // If --build-id was used, set up the build ID note.
2589 Layout::create_build_id()
2591 if (!parameters
->options().user_set_build_id())
2594 const char* style
= parameters
->options().build_id();
2595 if (strcmp(style
, "none") == 0)
2598 // Set DESCSZ to the size of the note descriptor. When possible,
2599 // set DESC to the note descriptor contents.
2602 if (strcmp(style
, "md5") == 0)
2604 else if (strcmp(style
, "sha1") == 0)
2606 else if (strcmp(style
, "uuid") == 0)
2608 const size_t uuidsz
= 128 / 8;
2610 char buffer
[uuidsz
];
2611 memset(buffer
, 0, uuidsz
);
2613 int descriptor
= open_descriptor(-1, "/dev/urandom", O_RDONLY
);
2615 gold_error(_("--build-id=uuid failed: could not open /dev/urandom: %s"),
2619 ssize_t got
= ::read(descriptor
, buffer
, uuidsz
);
2620 release_descriptor(descriptor
, true);
2622 gold_error(_("/dev/urandom: read failed: %s"), strerror(errno
));
2623 else if (static_cast<size_t>(got
) != uuidsz
)
2624 gold_error(_("/dev/urandom: expected %zu bytes, got %zd bytes"),
2628 desc
.assign(buffer
, uuidsz
);
2631 else if (strncmp(style
, "0x", 2) == 0)
2634 const char* p
= style
+ 2;
2637 if (hex_p(p
[0]) && hex_p(p
[1]))
2639 char c
= (hex_value(p
[0]) << 4) | hex_value(p
[1]);
2643 else if (*p
== '-' || *p
== ':')
2646 gold_fatal(_("--build-id argument '%s' not a valid hex number"),
2649 descsz
= desc
.size();
2652 gold_fatal(_("unrecognized --build-id argument '%s'"), style
);
2655 size_t trailing_padding
;
2656 Output_section
* os
= this->create_note("GNU", elfcpp::NT_GNU_BUILD_ID
,
2657 ".note.gnu.build-id", descsz
, true,
2664 // We know the value already, so we fill it in now.
2665 gold_assert(desc
.size() == descsz
);
2667 Output_section_data
* posd
= new Output_data_const(desc
, 4);
2668 os
->add_output_section_data(posd
);
2670 if (trailing_padding
!= 0)
2672 posd
= new Output_data_zero_fill(trailing_padding
, 0);
2673 os
->add_output_section_data(posd
);
2678 // We need to compute a checksum after we have completed the
2680 gold_assert(trailing_padding
== 0);
2681 this->build_id_note_
= new Output_data_zero_fill(descsz
, 4);
2682 os
->add_output_section_data(this->build_id_note_
);
2686 // If we have both .stabXX and .stabXXstr sections, then the sh_link
2687 // field of the former should point to the latter. I'm not sure who
2688 // started this, but the GNU linker does it, and some tools depend
2692 Layout::link_stabs_sections()
2694 if (!this->have_stabstr_section_
)
2697 for (Section_list::iterator p
= this->section_list_
.begin();
2698 p
!= this->section_list_
.end();
2701 if ((*p
)->type() != elfcpp::SHT_STRTAB
)
2704 const char* name
= (*p
)->name();
2705 if (strncmp(name
, ".stab", 5) != 0)
2708 size_t len
= strlen(name
);
2709 if (strcmp(name
+ len
- 3, "str") != 0)
2712 std::string
stab_name(name
, len
- 3);
2713 Output_section
* stab_sec
;
2714 stab_sec
= this->find_output_section(stab_name
.c_str());
2715 if (stab_sec
!= NULL
)
2716 stab_sec
->set_link_section(*p
);
2720 // Create .gnu_incremental_inputs and related sections needed
2721 // for the next run of incremental linking to check what has changed.
2724 Layout::create_incremental_info_sections(Symbol_table
* symtab
)
2726 Incremental_inputs
* incr
= this->incremental_inputs_
;
2728 gold_assert(incr
!= NULL
);
2730 // Create the .gnu_incremental_inputs, _symtab, and _relocs input sections.
2731 incr
->create_data_sections(symtab
);
2733 // Add the .gnu_incremental_inputs section.
2734 const char* incremental_inputs_name
=
2735 this->namepool_
.add(".gnu_incremental_inputs", false, NULL
);
2736 Output_section
* incremental_inputs_os
=
2737 this->make_output_section(incremental_inputs_name
,
2738 elfcpp::SHT_GNU_INCREMENTAL_INPUTS
, 0,
2739 ORDER_INVALID
, false);
2740 incremental_inputs_os
->add_output_section_data(incr
->inputs_section());
2742 // Add the .gnu_incremental_symtab section.
2743 const char* incremental_symtab_name
=
2744 this->namepool_
.add(".gnu_incremental_symtab", false, NULL
);
2745 Output_section
* incremental_symtab_os
=
2746 this->make_output_section(incremental_symtab_name
,
2747 elfcpp::SHT_GNU_INCREMENTAL_SYMTAB
, 0,
2748 ORDER_INVALID
, false);
2749 incremental_symtab_os
->add_output_section_data(incr
->symtab_section());
2750 incremental_symtab_os
->set_entsize(4);
2752 // Add the .gnu_incremental_relocs section.
2753 const char* incremental_relocs_name
=
2754 this->namepool_
.add(".gnu_incremental_relocs", false, NULL
);
2755 Output_section
* incremental_relocs_os
=
2756 this->make_output_section(incremental_relocs_name
,
2757 elfcpp::SHT_GNU_INCREMENTAL_RELOCS
, 0,
2758 ORDER_INVALID
, false);
2759 incremental_relocs_os
->add_output_section_data(incr
->relocs_section());
2760 incremental_relocs_os
->set_entsize(incr
->relocs_entsize());
2762 // Add the .gnu_incremental_got_plt section.
2763 const char* incremental_got_plt_name
=
2764 this->namepool_
.add(".gnu_incremental_got_plt", false, NULL
);
2765 Output_section
* incremental_got_plt_os
=
2766 this->make_output_section(incremental_got_plt_name
,
2767 elfcpp::SHT_GNU_INCREMENTAL_GOT_PLT
, 0,
2768 ORDER_INVALID
, false);
2769 incremental_got_plt_os
->add_output_section_data(incr
->got_plt_section());
2771 // Add the .gnu_incremental_strtab section.
2772 const char* incremental_strtab_name
=
2773 this->namepool_
.add(".gnu_incremental_strtab", false, NULL
);
2774 Output_section
* incremental_strtab_os
= this->make_output_section(incremental_strtab_name
,
2775 elfcpp::SHT_STRTAB
, 0,
2776 ORDER_INVALID
, false);
2777 Output_data_strtab
* strtab_data
=
2778 new Output_data_strtab(incr
->get_stringpool());
2779 incremental_strtab_os
->add_output_section_data(strtab_data
);
2781 incremental_inputs_os
->set_after_input_sections();
2782 incremental_symtab_os
->set_after_input_sections();
2783 incremental_relocs_os
->set_after_input_sections();
2784 incremental_got_plt_os
->set_after_input_sections();
2786 incremental_inputs_os
->set_link_section(incremental_strtab_os
);
2787 incremental_symtab_os
->set_link_section(incremental_inputs_os
);
2788 incremental_relocs_os
->set_link_section(incremental_inputs_os
);
2789 incremental_got_plt_os
->set_link_section(incremental_inputs_os
);
2792 // Return whether SEG1 should be before SEG2 in the output file. This
2793 // is based entirely on the segment type and flags. When this is
2794 // called the segment addresses have normally not yet been set.
2797 Layout::segment_precedes(const Output_segment
* seg1
,
2798 const Output_segment
* seg2
)
2800 elfcpp::Elf_Word type1
= seg1
->type();
2801 elfcpp::Elf_Word type2
= seg2
->type();
2803 // The single PT_PHDR segment is required to precede any loadable
2804 // segment. We simply make it always first.
2805 if (type1
== elfcpp::PT_PHDR
)
2807 gold_assert(type2
!= elfcpp::PT_PHDR
);
2810 if (type2
== elfcpp::PT_PHDR
)
2813 // The single PT_INTERP segment is required to precede any loadable
2814 // segment. We simply make it always second.
2815 if (type1
== elfcpp::PT_INTERP
)
2817 gold_assert(type2
!= elfcpp::PT_INTERP
);
2820 if (type2
== elfcpp::PT_INTERP
)
2823 // We then put PT_LOAD segments before any other segments.
2824 if (type1
== elfcpp::PT_LOAD
&& type2
!= elfcpp::PT_LOAD
)
2826 if (type2
== elfcpp::PT_LOAD
&& type1
!= elfcpp::PT_LOAD
)
2829 // We put the PT_TLS segment last except for the PT_GNU_RELRO
2830 // segment, because that is where the dynamic linker expects to find
2831 // it (this is just for efficiency; other positions would also work
2833 if (type1
== elfcpp::PT_TLS
2834 && type2
!= elfcpp::PT_TLS
2835 && type2
!= elfcpp::PT_GNU_RELRO
)
2837 if (type2
== elfcpp::PT_TLS
2838 && type1
!= elfcpp::PT_TLS
2839 && type1
!= elfcpp::PT_GNU_RELRO
)
2842 // We put the PT_GNU_RELRO segment last, because that is where the
2843 // dynamic linker expects to find it (as with PT_TLS, this is just
2845 if (type1
== elfcpp::PT_GNU_RELRO
&& type2
!= elfcpp::PT_GNU_RELRO
)
2847 if (type2
== elfcpp::PT_GNU_RELRO
&& type1
!= elfcpp::PT_GNU_RELRO
)
2850 const elfcpp::Elf_Word flags1
= seg1
->flags();
2851 const elfcpp::Elf_Word flags2
= seg2
->flags();
2853 // The order of non-PT_LOAD segments is unimportant. We simply sort
2854 // by the numeric segment type and flags values. There should not
2855 // be more than one segment with the same type and flags.
2856 if (type1
!= elfcpp::PT_LOAD
)
2859 return type1
< type2
;
2860 gold_assert(flags1
!= flags2
);
2861 return flags1
< flags2
;
2864 // If the addresses are set already, sort by load address.
2865 if (seg1
->are_addresses_set())
2867 if (!seg2
->are_addresses_set())
2870 unsigned int section_count1
= seg1
->output_section_count();
2871 unsigned int section_count2
= seg2
->output_section_count();
2872 if (section_count1
== 0 && section_count2
> 0)
2874 if (section_count1
> 0 && section_count2
== 0)
2877 uint64_t paddr1
= (seg1
->are_addresses_set()
2879 : seg1
->first_section_load_address());
2880 uint64_t paddr2
= (seg2
->are_addresses_set()
2882 : seg2
->first_section_load_address());
2884 if (paddr1
!= paddr2
)
2885 return paddr1
< paddr2
;
2887 else if (seg2
->are_addresses_set())
2890 // A segment which holds large data comes after a segment which does
2891 // not hold large data.
2892 if (seg1
->is_large_data_segment())
2894 if (!seg2
->is_large_data_segment())
2897 else if (seg2
->is_large_data_segment())
2900 // Otherwise, we sort PT_LOAD segments based on the flags. Readonly
2901 // segments come before writable segments. Then writable segments
2902 // with data come before writable segments without data. Then
2903 // executable segments come before non-executable segments. Then
2904 // the unlikely case of a non-readable segment comes before the
2905 // normal case of a readable segment. If there are multiple
2906 // segments with the same type and flags, we require that the
2907 // address be set, and we sort by virtual address and then physical
2909 if ((flags1
& elfcpp::PF_W
) != (flags2
& elfcpp::PF_W
))
2910 return (flags1
& elfcpp::PF_W
) == 0;
2911 if ((flags1
& elfcpp::PF_W
) != 0
2912 && seg1
->has_any_data_sections() != seg2
->has_any_data_sections())
2913 return seg1
->has_any_data_sections();
2914 if ((flags1
& elfcpp::PF_X
) != (flags2
& elfcpp::PF_X
))
2915 return (flags1
& elfcpp::PF_X
) != 0;
2916 if ((flags1
& elfcpp::PF_R
) != (flags2
& elfcpp::PF_R
))
2917 return (flags1
& elfcpp::PF_R
) == 0;
2919 // We shouldn't get here--we shouldn't create segments which we
2920 // can't distinguish. Unless of course we are using a weird linker
2922 gold_assert(this->script_options_
->saw_phdrs_clause());
2926 // Increase OFF so that it is congruent to ADDR modulo ABI_PAGESIZE.
2929 align_file_offset(off_t off
, uint64_t addr
, uint64_t abi_pagesize
)
2931 uint64_t unsigned_off
= off
;
2932 uint64_t aligned_off
= ((unsigned_off
& ~(abi_pagesize
- 1))
2933 | (addr
& (abi_pagesize
- 1)));
2934 if (aligned_off
< unsigned_off
)
2935 aligned_off
+= abi_pagesize
;
2939 // Set the file offsets of all the segments, and all the sections they
2940 // contain. They have all been created. LOAD_SEG must be be laid out
2941 // first. Return the offset of the data to follow.
2944 Layout::set_segment_offsets(const Target
* target
, Output_segment
* load_seg
,
2945 unsigned int* pshndx
)
2947 // Sort them into the final order. We use a stable sort so that we
2948 // don't randomize the order of indistinguishable segments created
2949 // by linker scripts.
2950 std::stable_sort(this->segment_list_
.begin(), this->segment_list_
.end(),
2951 Layout::Compare_segments(this));
2953 // Find the PT_LOAD segments, and set their addresses and offsets
2954 // and their section's addresses and offsets.
2956 if (parameters
->options().user_set_Ttext())
2957 addr
= parameters
->options().Ttext();
2958 else if (parameters
->options().output_is_position_independent())
2961 addr
= target
->default_text_segment_address();
2964 // If LOAD_SEG is NULL, then the file header and segment headers
2965 // will not be loadable. But they still need to be at offset 0 in
2966 // the file. Set their offsets now.
2967 if (load_seg
== NULL
)
2969 for (Data_list::iterator p
= this->special_output_list_
.begin();
2970 p
!= this->special_output_list_
.end();
2973 off
= align_address(off
, (*p
)->addralign());
2974 (*p
)->set_address_and_file_offset(0, off
);
2975 off
+= (*p
)->data_size();
2979 unsigned int increase_relro
= this->increase_relro_
;
2980 if (this->script_options_
->saw_sections_clause())
2983 const bool check_sections
= parameters
->options().check_sections();
2984 Output_segment
* last_load_segment
= NULL
;
2986 for (Segment_list::iterator p
= this->segment_list_
.begin();
2987 p
!= this->segment_list_
.end();
2990 if ((*p
)->type() == elfcpp::PT_LOAD
)
2992 if (load_seg
!= NULL
&& load_seg
!= *p
)
2996 bool are_addresses_set
= (*p
)->are_addresses_set();
2997 if (are_addresses_set
)
2999 // When it comes to setting file offsets, we care about
3000 // the physical address.
3001 addr
= (*p
)->paddr();
3003 else if (parameters
->options().user_set_Tdata()
3004 && ((*p
)->flags() & elfcpp::PF_W
) != 0
3005 && (!parameters
->options().user_set_Tbss()
3006 || (*p
)->has_any_data_sections()))
3008 addr
= parameters
->options().Tdata();
3009 are_addresses_set
= true;
3011 else if (parameters
->options().user_set_Tbss()
3012 && ((*p
)->flags() & elfcpp::PF_W
) != 0
3013 && !(*p
)->has_any_data_sections())
3015 addr
= parameters
->options().Tbss();
3016 are_addresses_set
= true;
3019 uint64_t orig_addr
= addr
;
3020 uint64_t orig_off
= off
;
3022 uint64_t aligned_addr
= 0;
3023 uint64_t abi_pagesize
= target
->abi_pagesize();
3024 uint64_t common_pagesize
= target
->common_pagesize();
3026 if (!parameters
->options().nmagic()
3027 && !parameters
->options().omagic())
3028 (*p
)->set_minimum_p_align(common_pagesize
);
3030 if (!are_addresses_set
)
3032 // Skip the address forward one page, maintaining the same
3033 // position within the page. This lets us store both segments
3034 // overlapping on a single page in the file, but the loader will
3035 // put them on different pages in memory. We will revisit this
3036 // decision once we know the size of the segment.
3038 addr
= align_address(addr
, (*p
)->maximum_alignment());
3039 aligned_addr
= addr
;
3041 if ((addr
& (abi_pagesize
- 1)) != 0)
3042 addr
= addr
+ abi_pagesize
;
3044 off
= orig_off
+ ((addr
- orig_addr
) & (abi_pagesize
- 1));
3047 if (!parameters
->options().nmagic()
3048 && !parameters
->options().omagic())
3049 off
= align_file_offset(off
, addr
, abi_pagesize
);
3050 else if (load_seg
== NULL
)
3052 // This is -N or -n with a section script which prevents
3053 // us from using a load segment. We need to ensure that
3054 // the file offset is aligned to the alignment of the
3055 // segment. This is because the linker script
3056 // implicitly assumed a zero offset. If we don't align
3057 // here, then the alignment of the sections in the
3058 // linker script may not match the alignment of the
3059 // sections in the set_section_addresses call below,
3060 // causing an error about dot moving backward.
3061 off
= align_address(off
, (*p
)->maximum_alignment());
3064 unsigned int shndx_hold
= *pshndx
;
3065 bool has_relro
= false;
3066 uint64_t new_addr
= (*p
)->set_section_addresses(this, false, addr
,
3071 // Now that we know the size of this segment, we may be able
3072 // to save a page in memory, at the cost of wasting some
3073 // file space, by instead aligning to the start of a new
3074 // page. Here we use the real machine page size rather than
3075 // the ABI mandated page size. If the segment has been
3076 // aligned so that the relro data ends at a page boundary,
3077 // we do not try to realign it.
3079 if (!are_addresses_set
3081 && aligned_addr
!= addr
3082 && !parameters
->incremental())
3084 uint64_t first_off
= (common_pagesize
3086 & (common_pagesize
- 1)));
3087 uint64_t last_off
= new_addr
& (common_pagesize
- 1);
3090 && ((aligned_addr
& ~ (common_pagesize
- 1))
3091 != (new_addr
& ~ (common_pagesize
- 1)))
3092 && first_off
+ last_off
<= common_pagesize
)
3094 *pshndx
= shndx_hold
;
3095 addr
= align_address(aligned_addr
, common_pagesize
);
3096 addr
= align_address(addr
, (*p
)->maximum_alignment());
3097 off
= orig_off
+ ((addr
- orig_addr
) & (abi_pagesize
- 1));
3098 off
= align_file_offset(off
, addr
, abi_pagesize
);
3100 increase_relro
= this->increase_relro_
;
3101 if (this->script_options_
->saw_sections_clause())
3105 new_addr
= (*p
)->set_section_addresses(this, true, addr
,
3114 // Implement --check-sections. We know that the segments
3115 // are sorted by LMA.
3116 if (check_sections
&& last_load_segment
!= NULL
)
3118 gold_assert(last_load_segment
->paddr() <= (*p
)->paddr());
3119 if (last_load_segment
->paddr() + last_load_segment
->memsz()
3122 unsigned long long lb1
= last_load_segment
->paddr();
3123 unsigned long long le1
= lb1
+ last_load_segment
->memsz();
3124 unsigned long long lb2
= (*p
)->paddr();
3125 unsigned long long le2
= lb2
+ (*p
)->memsz();
3126 gold_error(_("load segment overlap [0x%llx -> 0x%llx] and "
3127 "[0x%llx -> 0x%llx]"),
3128 lb1
, le1
, lb2
, le2
);
3131 last_load_segment
= *p
;
3135 // Handle the non-PT_LOAD segments, setting their offsets from their
3136 // section's offsets.
3137 for (Segment_list::iterator p
= this->segment_list_
.begin();
3138 p
!= this->segment_list_
.end();
3141 if ((*p
)->type() != elfcpp::PT_LOAD
)
3142 (*p
)->set_offset((*p
)->type() == elfcpp::PT_GNU_RELRO
3147 // Set the TLS offsets for each section in the PT_TLS segment.
3148 if (this->tls_segment_
!= NULL
)
3149 this->tls_segment_
->set_tls_offsets();
3154 // Set the offsets of all the allocated sections when doing a
3155 // relocatable link. This does the same jobs as set_segment_offsets,
3156 // only for a relocatable link.
3159 Layout::set_relocatable_section_offsets(Output_data
* file_header
,
3160 unsigned int* pshndx
)
3164 file_header
->set_address_and_file_offset(0, 0);
3165 off
+= file_header
->data_size();
3167 for (Section_list::iterator p
= this->section_list_
.begin();
3168 p
!= this->section_list_
.end();
3171 // We skip unallocated sections here, except that group sections
3172 // have to come first.
3173 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) == 0
3174 && (*p
)->type() != elfcpp::SHT_GROUP
)
3177 off
= align_address(off
, (*p
)->addralign());
3179 // The linker script might have set the address.
3180 if (!(*p
)->is_address_valid())
3181 (*p
)->set_address(0);
3182 (*p
)->set_file_offset(off
);
3183 (*p
)->finalize_data_size();
3184 off
+= (*p
)->data_size();
3186 (*p
)->set_out_shndx(*pshndx
);
3193 // Set the file offset of all the sections not associated with a
3197 Layout::set_section_offsets(off_t off
, Layout::Section_offset_pass pass
)
3199 off_t startoff
= off
;
3202 for (Section_list::iterator p
= this->unattached_section_list_
.begin();
3203 p
!= this->unattached_section_list_
.end();
3206 // The symtab section is handled in create_symtab_sections.
3207 if (*p
== this->symtab_section_
)
3210 // If we've already set the data size, don't set it again.
3211 if ((*p
)->is_offset_valid() && (*p
)->is_data_size_valid())
3214 if (pass
== BEFORE_INPUT_SECTIONS_PASS
3215 && (*p
)->requires_postprocessing())
3217 (*p
)->create_postprocessing_buffer();
3218 this->any_postprocessing_sections_
= true;
3221 if (pass
== BEFORE_INPUT_SECTIONS_PASS
3222 && (*p
)->after_input_sections())
3224 else if (pass
== POSTPROCESSING_SECTIONS_PASS
3225 && (!(*p
)->after_input_sections()
3226 || (*p
)->type() == elfcpp::SHT_STRTAB
))
3228 else if (pass
== STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
3229 && (!(*p
)->after_input_sections()
3230 || (*p
)->type() != elfcpp::SHT_STRTAB
))
3233 if (!parameters
->incremental_update())
3235 off
= align_address(off
, (*p
)->addralign());
3236 (*p
)->set_file_offset(off
);
3237 (*p
)->finalize_data_size();
3241 // Incremental update: allocate file space from free list.
3242 (*p
)->pre_finalize_data_size();
3243 off_t current_size
= (*p
)->current_data_size();
3244 off
= this->allocate(current_size
, (*p
)->addralign(), startoff
);
3247 if (is_debugging_enabled(DEBUG_INCREMENTAL
))
3248 this->free_list_
.dump();
3249 gold_assert((*p
)->output_section() != NULL
);
3250 gold_fallback(_("out of patch space for section %s; "
3251 "relink with --incremental-full"),
3252 (*p
)->output_section()->name());
3254 (*p
)->set_file_offset(off
);
3255 (*p
)->finalize_data_size();
3256 if ((*p
)->data_size() > current_size
)
3258 gold_assert((*p
)->output_section() != NULL
);
3259 gold_fallback(_("%s: section changed size; "
3260 "relink with --incremental-full"),
3261 (*p
)->output_section()->name());
3263 gold_debug(DEBUG_INCREMENTAL
,
3264 "set_section_offsets: %08lx %08lx %s",
3265 static_cast<long>(off
),
3266 static_cast<long>((*p
)->data_size()),
3267 ((*p
)->output_section() != NULL
3268 ? (*p
)->output_section()->name() : "(special)"));
3271 off
+= (*p
)->data_size();
3275 // At this point the name must be set.
3276 if (pass
!= STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
)
3277 this->namepool_
.add((*p
)->name(), false, NULL
);
3282 // Set the section indexes of all the sections not associated with a
3286 Layout::set_section_indexes(unsigned int shndx
)
3288 for (Section_list::iterator p
= this->unattached_section_list_
.begin();
3289 p
!= this->unattached_section_list_
.end();
3292 if (!(*p
)->has_out_shndx())
3294 (*p
)->set_out_shndx(shndx
);
3301 // Set the section addresses according to the linker script. This is
3302 // only called when we see a SECTIONS clause. This returns the
3303 // program segment which should hold the file header and segment
3304 // headers, if any. It will return NULL if they should not be in a
3308 Layout::set_section_addresses_from_script(Symbol_table
* symtab
)
3310 Script_sections
* ss
= this->script_options_
->script_sections();
3311 gold_assert(ss
->saw_sections_clause());
3312 return this->script_options_
->set_section_addresses(symtab
, this);
3315 // Place the orphan sections in the linker script.
3318 Layout::place_orphan_sections_in_script()
3320 Script_sections
* ss
= this->script_options_
->script_sections();
3321 gold_assert(ss
->saw_sections_clause());
3323 // Place each orphaned output section in the script.
3324 for (Section_list::iterator p
= this->section_list_
.begin();
3325 p
!= this->section_list_
.end();
3328 if (!(*p
)->found_in_sections_clause())
3329 ss
->place_orphan(*p
);
3333 // Count the local symbols in the regular symbol table and the dynamic
3334 // symbol table, and build the respective string pools.
3337 Layout::count_local_symbols(const Task
* task
,
3338 const Input_objects
* input_objects
)
3340 // First, figure out an upper bound on the number of symbols we'll
3341 // be inserting into each pool. This helps us create the pools with
3342 // the right size, to avoid unnecessary hashtable resizing.
3343 unsigned int symbol_count
= 0;
3344 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
3345 p
!= input_objects
->relobj_end();
3347 symbol_count
+= (*p
)->local_symbol_count();
3349 // Go from "upper bound" to "estimate." We overcount for two
3350 // reasons: we double-count symbols that occur in more than one
3351 // object file, and we count symbols that are dropped from the
3352 // output. Add it all together and assume we overcount by 100%.
3355 // We assume all symbols will go into both the sympool and dynpool.
3356 this->sympool_
.reserve(symbol_count
);
3357 this->dynpool_
.reserve(symbol_count
);
3359 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
3360 p
!= input_objects
->relobj_end();
3363 Task_lock_obj
<Object
> tlo(task
, *p
);
3364 (*p
)->count_local_symbols(&this->sympool_
, &this->dynpool_
);
3368 // Create the symbol table sections. Here we also set the final
3369 // values of the symbols. At this point all the loadable sections are
3370 // fully laid out. SHNUM is the number of sections so far.
3373 Layout::create_symtab_sections(const Input_objects
* input_objects
,
3374 Symbol_table
* symtab
,
3380 if (parameters
->target().get_size() == 32)
3382 symsize
= elfcpp::Elf_sizes
<32>::sym_size
;
3385 else if (parameters
->target().get_size() == 64)
3387 symsize
= elfcpp::Elf_sizes
<64>::sym_size
;
3393 // Compute file offsets relative to the start of the symtab section.
3396 // Save space for the dummy symbol at the start of the section. We
3397 // never bother to write this out--it will just be left as zero.
3399 unsigned int local_symbol_index
= 1;
3401 // Add STT_SECTION symbols for each Output section which needs one.
3402 for (Section_list::iterator p
= this->section_list_
.begin();
3403 p
!= this->section_list_
.end();
3406 if (!(*p
)->needs_symtab_index())
3407 (*p
)->set_symtab_index(-1U);
3410 (*p
)->set_symtab_index(local_symbol_index
);
3411 ++local_symbol_index
;
3416 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
3417 p
!= input_objects
->relobj_end();
3420 unsigned int index
= (*p
)->finalize_local_symbols(local_symbol_index
,
3422 off
+= (index
- local_symbol_index
) * symsize
;
3423 local_symbol_index
= index
;
3426 unsigned int local_symcount
= local_symbol_index
;
3427 gold_assert(static_cast<off_t
>(local_symcount
* symsize
) == off
);
3430 size_t dyn_global_index
;
3432 if (this->dynsym_section_
== NULL
)
3435 dyn_global_index
= 0;
3440 dyn_global_index
= this->dynsym_section_
->info();
3441 off_t locsize
= dyn_global_index
* this->dynsym_section_
->entsize();
3442 dynoff
= this->dynsym_section_
->offset() + locsize
;
3443 dyncount
= (this->dynsym_section_
->data_size() - locsize
) / symsize
;
3444 gold_assert(static_cast<off_t
>(dyncount
* symsize
)
3445 == this->dynsym_section_
->data_size() - locsize
);
3448 off_t global_off
= off
;
3449 off
= symtab
->finalize(off
, dynoff
, dyn_global_index
, dyncount
,
3450 &this->sympool_
, &local_symcount
);
3452 if (!parameters
->options().strip_all())
3454 this->sympool_
.set_string_offsets();
3456 const char* symtab_name
= this->namepool_
.add(".symtab", false, NULL
);
3457 Output_section
* osymtab
= this->make_output_section(symtab_name
,
3461 this->symtab_section_
= osymtab
;
3463 Output_section_data
* pos
= new Output_data_fixed_space(off
, align
,
3465 osymtab
->add_output_section_data(pos
);
3467 // We generate a .symtab_shndx section if we have more than
3468 // SHN_LORESERVE sections. Technically it is possible that we
3469 // don't need one, because it is possible that there are no
3470 // symbols in any of sections with indexes larger than
3471 // SHN_LORESERVE. That is probably unusual, though, and it is
3472 // easier to always create one than to compute section indexes
3473 // twice (once here, once when writing out the symbols).
3474 if (shnum
>= elfcpp::SHN_LORESERVE
)
3476 const char* symtab_xindex_name
= this->namepool_
.add(".symtab_shndx",
3478 Output_section
* osymtab_xindex
=
3479 this->make_output_section(symtab_xindex_name
,
3480 elfcpp::SHT_SYMTAB_SHNDX
, 0,
3481 ORDER_INVALID
, false);
3483 size_t symcount
= off
/ symsize
;
3484 this->symtab_xindex_
= new Output_symtab_xindex(symcount
);
3486 osymtab_xindex
->add_output_section_data(this->symtab_xindex_
);
3488 osymtab_xindex
->set_link_section(osymtab
);
3489 osymtab_xindex
->set_addralign(4);
3490 osymtab_xindex
->set_entsize(4);
3492 osymtab_xindex
->set_after_input_sections();
3494 // This tells the driver code to wait until the symbol table
3495 // has written out before writing out the postprocessing
3496 // sections, including the .symtab_shndx section.
3497 this->any_postprocessing_sections_
= true;
3500 const char* strtab_name
= this->namepool_
.add(".strtab", false, NULL
);
3501 Output_section
* ostrtab
= this->make_output_section(strtab_name
,
3506 Output_section_data
* pstr
= new Output_data_strtab(&this->sympool_
);
3507 ostrtab
->add_output_section_data(pstr
);
3510 if (!parameters
->incremental_update())
3511 symtab_off
= align_address(*poff
, align
);
3514 symtab_off
= this->allocate(off
, align
, *poff
);
3516 gold_fallback(_("out of patch space for symbol table; "
3517 "relink with --incremental-full"));
3518 gold_debug(DEBUG_INCREMENTAL
,
3519 "create_symtab_sections: %08lx %08lx .symtab",
3520 static_cast<long>(symtab_off
),
3521 static_cast<long>(off
));
3524 symtab
->set_file_offset(symtab_off
+ global_off
);
3525 osymtab
->set_file_offset(symtab_off
);
3526 osymtab
->finalize_data_size();
3527 osymtab
->set_link_section(ostrtab
);
3528 osymtab
->set_info(local_symcount
);
3529 osymtab
->set_entsize(symsize
);
3531 if (symtab_off
+ off
> *poff
)
3532 *poff
= symtab_off
+ off
;
3536 // Create the .shstrtab section, which holds the names of the
3537 // sections. At the time this is called, we have created all the
3538 // output sections except .shstrtab itself.
3541 Layout::create_shstrtab()
3543 // FIXME: We don't need to create a .shstrtab section if we are
3544 // stripping everything.
3546 const char* name
= this->namepool_
.add(".shstrtab", false, NULL
);
3548 Output_section
* os
= this->make_output_section(name
, elfcpp::SHT_STRTAB
, 0,
3549 ORDER_INVALID
, false);
3551 if (strcmp(parameters
->options().compress_debug_sections(), "none") != 0)
3553 // We can't write out this section until we've set all the
3554 // section names, and we don't set the names of compressed
3555 // output sections until relocations are complete. FIXME: With
3556 // the current names we use, this is unnecessary.
3557 os
->set_after_input_sections();
3560 Output_section_data
* posd
= new Output_data_strtab(&this->namepool_
);
3561 os
->add_output_section_data(posd
);
3566 // Create the section headers. SIZE is 32 or 64. OFF is the file
3570 Layout::create_shdrs(const Output_section
* shstrtab_section
, off_t
* poff
)
3572 Output_section_headers
* oshdrs
;
3573 oshdrs
= new Output_section_headers(this,
3574 &this->segment_list_
,
3575 &this->section_list_
,
3576 &this->unattached_section_list_
,
3580 if (!parameters
->incremental_update())
3581 off
= align_address(*poff
, oshdrs
->addralign());
3584 oshdrs
->pre_finalize_data_size();
3585 off
= this->allocate(oshdrs
->data_size(), oshdrs
->addralign(), *poff
);
3587 gold_fallback(_("out of patch space for section header table; "
3588 "relink with --incremental-full"));
3589 gold_debug(DEBUG_INCREMENTAL
,
3590 "create_shdrs: %08lx %08lx (section header table)",
3591 static_cast<long>(off
),
3592 static_cast<long>(off
+ oshdrs
->data_size()));
3594 oshdrs
->set_address_and_file_offset(0, off
);
3595 off
+= oshdrs
->data_size();
3598 this->section_headers_
= oshdrs
;
3601 // Count the allocated sections.
3604 Layout::allocated_output_section_count() const
3606 size_t section_count
= 0;
3607 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
3608 p
!= this->segment_list_
.end();
3610 section_count
+= (*p
)->output_section_count();
3611 return section_count
;
3614 // Create the dynamic symbol table.
3617 Layout::create_dynamic_symtab(const Input_objects
* input_objects
,
3618 Symbol_table
* symtab
,
3619 Output_section
** pdynstr
,
3620 unsigned int* plocal_dynamic_count
,
3621 std::vector
<Symbol
*>* pdynamic_symbols
,
3622 Versions
* pversions
)
3624 // Count all the symbols in the dynamic symbol table, and set the
3625 // dynamic symbol indexes.
3627 // Skip symbol 0, which is always all zeroes.
3628 unsigned int index
= 1;
3630 // Add STT_SECTION symbols for each Output section which needs one.
3631 for (Section_list::iterator p
= this->section_list_
.begin();
3632 p
!= this->section_list_
.end();
3635 if (!(*p
)->needs_dynsym_index())
3636 (*p
)->set_dynsym_index(-1U);
3639 (*p
)->set_dynsym_index(index
);
3644 // Count the local symbols that need to go in the dynamic symbol table,
3645 // and set the dynamic symbol indexes.
3646 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
3647 p
!= input_objects
->relobj_end();
3650 unsigned int new_index
= (*p
)->set_local_dynsym_indexes(index
);
3654 unsigned int local_symcount
= index
;
3655 *plocal_dynamic_count
= local_symcount
;
3657 index
= symtab
->set_dynsym_indexes(index
, pdynamic_symbols
,
3658 &this->dynpool_
, pversions
);
3662 const int size
= parameters
->target().get_size();
3665 symsize
= elfcpp::Elf_sizes
<32>::sym_size
;
3668 else if (size
== 64)
3670 symsize
= elfcpp::Elf_sizes
<64>::sym_size
;
3676 // Create the dynamic symbol table section.
3678 Output_section
* dynsym
= this->choose_output_section(NULL
, ".dynsym",
3682 ORDER_DYNAMIC_LINKER
,
3685 Output_section_data
* odata
= new Output_data_fixed_space(index
* symsize
,
3688 dynsym
->add_output_section_data(odata
);
3690 dynsym
->set_info(local_symcount
);
3691 dynsym
->set_entsize(symsize
);
3692 dynsym
->set_addralign(align
);
3694 this->dynsym_section_
= dynsym
;
3696 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
3697 odyn
->add_section_address(elfcpp::DT_SYMTAB
, dynsym
);
3698 odyn
->add_constant(elfcpp::DT_SYMENT
, symsize
);
3700 // If there are more than SHN_LORESERVE allocated sections, we
3701 // create a .dynsym_shndx section. It is possible that we don't
3702 // need one, because it is possible that there are no dynamic
3703 // symbols in any of the sections with indexes larger than
3704 // SHN_LORESERVE. This is probably unusual, though, and at this
3705 // time we don't know the actual section indexes so it is
3706 // inconvenient to check.
3707 if (this->allocated_output_section_count() >= elfcpp::SHN_LORESERVE
)
3709 Output_section
* dynsym_xindex
=
3710 this->choose_output_section(NULL
, ".dynsym_shndx",
3711 elfcpp::SHT_SYMTAB_SHNDX
,
3713 false, ORDER_DYNAMIC_LINKER
, false);
3715 this->dynsym_xindex_
= new Output_symtab_xindex(index
);
3717 dynsym_xindex
->add_output_section_data(this->dynsym_xindex_
);
3719 dynsym_xindex
->set_link_section(dynsym
);
3720 dynsym_xindex
->set_addralign(4);
3721 dynsym_xindex
->set_entsize(4);
3723 dynsym_xindex
->set_after_input_sections();
3725 // This tells the driver code to wait until the symbol table has
3726 // written out before writing out the postprocessing sections,
3727 // including the .dynsym_shndx section.
3728 this->any_postprocessing_sections_
= true;
3731 // Create the dynamic string table section.
3733 Output_section
* dynstr
= this->choose_output_section(NULL
, ".dynstr",
3737 ORDER_DYNAMIC_LINKER
,
3740 Output_section_data
* strdata
= new Output_data_strtab(&this->dynpool_
);
3741 dynstr
->add_output_section_data(strdata
);
3743 dynsym
->set_link_section(dynstr
);
3744 this->dynamic_section_
->set_link_section(dynstr
);
3746 odyn
->add_section_address(elfcpp::DT_STRTAB
, dynstr
);
3747 odyn
->add_section_size(elfcpp::DT_STRSZ
, dynstr
);
3751 // Create the hash tables.
3753 if (strcmp(parameters
->options().hash_style(), "sysv") == 0
3754 || strcmp(parameters
->options().hash_style(), "both") == 0)
3756 unsigned char* phash
;
3757 unsigned int hashlen
;
3758 Dynobj::create_elf_hash_table(*pdynamic_symbols
, local_symcount
,
3761 Output_section
* hashsec
=
3762 this->choose_output_section(NULL
, ".hash", elfcpp::SHT_HASH
,
3763 elfcpp::SHF_ALLOC
, false,
3764 ORDER_DYNAMIC_LINKER
, false);
3766 Output_section_data
* hashdata
= new Output_data_const_buffer(phash
,
3770 hashsec
->add_output_section_data(hashdata
);
3772 hashsec
->set_link_section(dynsym
);
3773 hashsec
->set_entsize(4);
3775 odyn
->add_section_address(elfcpp::DT_HASH
, hashsec
);
3778 if (strcmp(parameters
->options().hash_style(), "gnu") == 0
3779 || strcmp(parameters
->options().hash_style(), "both") == 0)
3781 unsigned char* phash
;
3782 unsigned int hashlen
;
3783 Dynobj::create_gnu_hash_table(*pdynamic_symbols
, local_symcount
,
3786 Output_section
* hashsec
=
3787 this->choose_output_section(NULL
, ".gnu.hash", elfcpp::SHT_GNU_HASH
,
3788 elfcpp::SHF_ALLOC
, false,
3789 ORDER_DYNAMIC_LINKER
, false);
3791 Output_section_data
* hashdata
= new Output_data_const_buffer(phash
,
3795 hashsec
->add_output_section_data(hashdata
);
3797 hashsec
->set_link_section(dynsym
);
3799 // For a 64-bit target, the entries in .gnu.hash do not have a
3800 // uniform size, so we only set the entry size for a 32-bit
3802 if (parameters
->target().get_size() == 32)
3803 hashsec
->set_entsize(4);
3805 odyn
->add_section_address(elfcpp::DT_GNU_HASH
, hashsec
);
3809 // Assign offsets to each local portion of the dynamic symbol table.
3812 Layout::assign_local_dynsym_offsets(const Input_objects
* input_objects
)
3814 Output_section
* dynsym
= this->dynsym_section_
;
3815 gold_assert(dynsym
!= NULL
);
3817 off_t off
= dynsym
->offset();
3819 // Skip the dummy symbol at the start of the section.
3820 off
+= dynsym
->entsize();
3822 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
3823 p
!= input_objects
->relobj_end();
3826 unsigned int count
= (*p
)->set_local_dynsym_offset(off
);
3827 off
+= count
* dynsym
->entsize();
3831 // Create the version sections.
3834 Layout::create_version_sections(const Versions
* versions
,
3835 const Symbol_table
* symtab
,
3836 unsigned int local_symcount
,
3837 const std::vector
<Symbol
*>& dynamic_symbols
,
3838 const Output_section
* dynstr
)
3840 if (!versions
->any_defs() && !versions
->any_needs())
3843 switch (parameters
->size_and_endianness())
3845 #ifdef HAVE_TARGET_32_LITTLE
3846 case Parameters::TARGET_32_LITTLE
:
3847 this->sized_create_version_sections
<32, false>(versions
, symtab
,
3849 dynamic_symbols
, dynstr
);
3852 #ifdef HAVE_TARGET_32_BIG
3853 case Parameters::TARGET_32_BIG
:
3854 this->sized_create_version_sections
<32, true>(versions
, symtab
,
3856 dynamic_symbols
, dynstr
);
3859 #ifdef HAVE_TARGET_64_LITTLE
3860 case Parameters::TARGET_64_LITTLE
:
3861 this->sized_create_version_sections
<64, false>(versions
, symtab
,
3863 dynamic_symbols
, dynstr
);
3866 #ifdef HAVE_TARGET_64_BIG
3867 case Parameters::TARGET_64_BIG
:
3868 this->sized_create_version_sections
<64, true>(versions
, symtab
,
3870 dynamic_symbols
, dynstr
);
3878 // Create the version sections, sized version.
3880 template<int size
, bool big_endian
>
3882 Layout::sized_create_version_sections(
3883 const Versions
* versions
,
3884 const Symbol_table
* symtab
,
3885 unsigned int local_symcount
,
3886 const std::vector
<Symbol
*>& dynamic_symbols
,
3887 const Output_section
* dynstr
)
3889 Output_section
* vsec
= this->choose_output_section(NULL
, ".gnu.version",
3890 elfcpp::SHT_GNU_versym
,
3893 ORDER_DYNAMIC_LINKER
,
3896 unsigned char* vbuf
;
3898 versions
->symbol_section_contents
<size
, big_endian
>(symtab
, &this->dynpool_
,
3903 Output_section_data
* vdata
= new Output_data_const_buffer(vbuf
, vsize
, 2,
3906 vsec
->add_output_section_data(vdata
);
3907 vsec
->set_entsize(2);
3908 vsec
->set_link_section(this->dynsym_section_
);
3910 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
3911 odyn
->add_section_address(elfcpp::DT_VERSYM
, vsec
);
3913 if (versions
->any_defs())
3915 Output_section
* vdsec
;
3916 vdsec
= this->choose_output_section(NULL
, ".gnu.version_d",
3917 elfcpp::SHT_GNU_verdef
,
3919 false, ORDER_DYNAMIC_LINKER
, false);
3921 unsigned char* vdbuf
;
3922 unsigned int vdsize
;
3923 unsigned int vdentries
;
3924 versions
->def_section_contents
<size
, big_endian
>(&this->dynpool_
, &vdbuf
,
3925 &vdsize
, &vdentries
);
3927 Output_section_data
* vddata
=
3928 new Output_data_const_buffer(vdbuf
, vdsize
, 4, "** version defs");
3930 vdsec
->add_output_section_data(vddata
);
3931 vdsec
->set_link_section(dynstr
);
3932 vdsec
->set_info(vdentries
);
3934 odyn
->add_section_address(elfcpp::DT_VERDEF
, vdsec
);
3935 odyn
->add_constant(elfcpp::DT_VERDEFNUM
, vdentries
);
3938 if (versions
->any_needs())
3940 Output_section
* vnsec
;
3941 vnsec
= this->choose_output_section(NULL
, ".gnu.version_r",
3942 elfcpp::SHT_GNU_verneed
,
3944 false, ORDER_DYNAMIC_LINKER
, false);
3946 unsigned char* vnbuf
;
3947 unsigned int vnsize
;
3948 unsigned int vnentries
;
3949 versions
->need_section_contents
<size
, big_endian
>(&this->dynpool_
,
3953 Output_section_data
* vndata
=
3954 new Output_data_const_buffer(vnbuf
, vnsize
, 4, "** version refs");
3956 vnsec
->add_output_section_data(vndata
);
3957 vnsec
->set_link_section(dynstr
);
3958 vnsec
->set_info(vnentries
);
3960 odyn
->add_section_address(elfcpp::DT_VERNEED
, vnsec
);
3961 odyn
->add_constant(elfcpp::DT_VERNEEDNUM
, vnentries
);
3965 // Create the .interp section and PT_INTERP segment.
3968 Layout::create_interp(const Target
* target
)
3970 gold_assert(this->interp_segment_
== NULL
);
3972 const char* interp
= parameters
->options().dynamic_linker();
3975 interp
= target
->dynamic_linker();
3976 gold_assert(interp
!= NULL
);
3979 size_t len
= strlen(interp
) + 1;
3981 Output_section_data
* odata
= new Output_data_const(interp
, len
, 1);
3983 Output_section
* osec
= this->choose_output_section(NULL
, ".interp",
3984 elfcpp::SHT_PROGBITS
,
3986 false, ORDER_INTERP
,
3988 osec
->add_output_section_data(odata
);
3991 // Add dynamic tags for the PLT and the dynamic relocs. This is
3992 // called by the target-specific code. This does nothing if not doing
3995 // USE_REL is true for REL relocs rather than RELA relocs.
3997 // If PLT_GOT is not NULL, then DT_PLTGOT points to it.
3999 // If PLT_REL is not NULL, it is used for DT_PLTRELSZ, and DT_JMPREL,
4000 // and we also set DT_PLTREL. We use PLT_REL's output section, since
4001 // some targets have multiple reloc sections in PLT_REL.
4003 // If DYN_REL is not NULL, it is used for DT_REL/DT_RELA,
4004 // DT_RELSZ/DT_RELASZ, DT_RELENT/DT_RELAENT.
4006 // If ADD_DEBUG is true, we add a DT_DEBUG entry when generating an
4010 Layout::add_target_dynamic_tags(bool use_rel
, const Output_data
* plt_got
,
4011 const Output_data
* plt_rel
,
4012 const Output_data_reloc_generic
* dyn_rel
,
4013 bool add_debug
, bool dynrel_includes_plt
)
4015 Output_data_dynamic
* odyn
= this->dynamic_data_
;
4019 if (plt_got
!= NULL
&& plt_got
->output_section() != NULL
)
4020 odyn
->add_section_address(elfcpp::DT_PLTGOT
, plt_got
);
4022 if (plt_rel
!= NULL
&& plt_rel
->output_section() != NULL
)
4024 odyn
->add_section_size(elfcpp::DT_PLTRELSZ
, plt_rel
->output_section());
4025 odyn
->add_section_address(elfcpp::DT_JMPREL
, plt_rel
->output_section());
4026 odyn
->add_constant(elfcpp::DT_PLTREL
,
4027 use_rel
? elfcpp::DT_REL
: elfcpp::DT_RELA
);
4030 if (dyn_rel
!= NULL
&& dyn_rel
->output_section() != NULL
)
4032 odyn
->add_section_address(use_rel
? elfcpp::DT_REL
: elfcpp::DT_RELA
,
4034 if (plt_rel
!= NULL
&& dynrel_includes_plt
)
4035 odyn
->add_section_size(use_rel
? elfcpp::DT_RELSZ
: elfcpp::DT_RELASZ
,
4038 odyn
->add_section_size(use_rel
? elfcpp::DT_RELSZ
: elfcpp::DT_RELASZ
,
4040 const int size
= parameters
->target().get_size();
4045 rel_tag
= elfcpp::DT_RELENT
;
4047 rel_size
= Reloc_types
<elfcpp::SHT_REL
, 32, false>::reloc_size
;
4048 else if (size
== 64)
4049 rel_size
= Reloc_types
<elfcpp::SHT_REL
, 64, false>::reloc_size
;
4055 rel_tag
= elfcpp::DT_RELAENT
;
4057 rel_size
= Reloc_types
<elfcpp::SHT_RELA
, 32, false>::reloc_size
;
4058 else if (size
== 64)
4059 rel_size
= Reloc_types
<elfcpp::SHT_RELA
, 64, false>::reloc_size
;
4063 odyn
->add_constant(rel_tag
, rel_size
);
4065 if (parameters
->options().combreloc())
4067 size_t c
= dyn_rel
->relative_reloc_count();
4069 odyn
->add_constant((use_rel
4070 ? elfcpp::DT_RELCOUNT
4071 : elfcpp::DT_RELACOUNT
),
4076 if (add_debug
&& !parameters
->options().shared())
4078 // The value of the DT_DEBUG tag is filled in by the dynamic
4079 // linker at run time, and used by the debugger.
4080 odyn
->add_constant(elfcpp::DT_DEBUG
, 0);
4084 // Finish the .dynamic section and PT_DYNAMIC segment.
4087 Layout::finish_dynamic_section(const Input_objects
* input_objects
,
4088 const Symbol_table
* symtab
)
4090 if (!this->script_options_
->saw_phdrs_clause())
4092 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_DYNAMIC
,
4095 oseg
->add_output_section_to_nonload(this->dynamic_section_
,
4096 elfcpp::PF_R
| elfcpp::PF_W
);
4099 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
4101 for (Input_objects::Dynobj_iterator p
= input_objects
->dynobj_begin();
4102 p
!= input_objects
->dynobj_end();
4105 if (!(*p
)->is_needed() && (*p
)->as_needed())
4107 // This dynamic object was linked with --as-needed, but it
4112 odyn
->add_string(elfcpp::DT_NEEDED
, (*p
)->soname());
4115 if (parameters
->options().shared())
4117 const char* soname
= parameters
->options().soname();
4119 odyn
->add_string(elfcpp::DT_SONAME
, soname
);
4122 Symbol
* sym
= symtab
->lookup(parameters
->options().init());
4123 if (sym
!= NULL
&& sym
->is_defined() && !sym
->is_from_dynobj())
4124 odyn
->add_symbol(elfcpp::DT_INIT
, sym
);
4126 sym
= symtab
->lookup(parameters
->options().fini());
4127 if (sym
!= NULL
&& sym
->is_defined() && !sym
->is_from_dynobj())
4128 odyn
->add_symbol(elfcpp::DT_FINI
, sym
);
4130 // Look for .init_array, .preinit_array and .fini_array by checking
4132 for(Layout::Section_list::const_iterator p
= this->section_list_
.begin();
4133 p
!= this->section_list_
.end();
4135 switch((*p
)->type())
4137 case elfcpp::SHT_FINI_ARRAY
:
4138 odyn
->add_section_address(elfcpp::DT_FINI_ARRAY
, *p
);
4139 odyn
->add_section_size(elfcpp::DT_FINI_ARRAYSZ
, *p
);
4141 case elfcpp::SHT_INIT_ARRAY
:
4142 odyn
->add_section_address(elfcpp::DT_INIT_ARRAY
, *p
);
4143 odyn
->add_section_size(elfcpp::DT_INIT_ARRAYSZ
, *p
);
4145 case elfcpp::SHT_PREINIT_ARRAY
:
4146 odyn
->add_section_address(elfcpp::DT_PREINIT_ARRAY
, *p
);
4147 odyn
->add_section_size(elfcpp::DT_PREINIT_ARRAYSZ
, *p
);
4153 // Add a DT_RPATH entry if needed.
4154 const General_options::Dir_list
& rpath(parameters
->options().rpath());
4157 std::string rpath_val
;
4158 for (General_options::Dir_list::const_iterator p
= rpath
.begin();
4162 if (rpath_val
.empty())
4163 rpath_val
= p
->name();
4166 // Eliminate duplicates.
4167 General_options::Dir_list::const_iterator q
;
4168 for (q
= rpath
.begin(); q
!= p
; ++q
)
4169 if (q
->name() == p
->name())
4174 rpath_val
+= p
->name();
4179 odyn
->add_string(elfcpp::DT_RPATH
, rpath_val
);
4180 if (parameters
->options().enable_new_dtags())
4181 odyn
->add_string(elfcpp::DT_RUNPATH
, rpath_val
);
4184 // Look for text segments that have dynamic relocations.
4185 bool have_textrel
= false;
4186 if (!this->script_options_
->saw_sections_clause())
4188 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
4189 p
!= this->segment_list_
.end();
4192 if ((*p
)->type() == elfcpp::PT_LOAD
4193 && ((*p
)->flags() & elfcpp::PF_W
) == 0
4194 && (*p
)->has_dynamic_reloc())
4196 have_textrel
= true;
4203 // We don't know the section -> segment mapping, so we are
4204 // conservative and just look for readonly sections with
4205 // relocations. If those sections wind up in writable segments,
4206 // then we have created an unnecessary DT_TEXTREL entry.
4207 for (Section_list::const_iterator p
= this->section_list_
.begin();
4208 p
!= this->section_list_
.end();
4211 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) != 0
4212 && ((*p
)->flags() & elfcpp::SHF_WRITE
) == 0
4213 && (*p
)->has_dynamic_reloc())
4215 have_textrel
= true;
4221 // Add a DT_FLAGS entry. We add it even if no flags are set so that
4222 // post-link tools can easily modify these flags if desired.
4223 unsigned int flags
= 0;
4226 // Add a DT_TEXTREL for compatibility with older loaders.
4227 odyn
->add_constant(elfcpp::DT_TEXTREL
, 0);
4228 flags
|= elfcpp::DF_TEXTREL
;
4230 if (parameters
->options().text())
4231 gold_error(_("read-only segment has dynamic relocations"));
4232 else if (parameters
->options().warn_shared_textrel()
4233 && parameters
->options().shared())
4234 gold_warning(_("shared library text segment is not shareable"));
4236 if (parameters
->options().shared() && this->has_static_tls())
4237 flags
|= elfcpp::DF_STATIC_TLS
;
4238 if (parameters
->options().origin())
4239 flags
|= elfcpp::DF_ORIGIN
;
4240 if (parameters
->options().Bsymbolic())
4242 flags
|= elfcpp::DF_SYMBOLIC
;
4243 // Add DT_SYMBOLIC for compatibility with older loaders.
4244 odyn
->add_constant(elfcpp::DT_SYMBOLIC
, 0);
4246 if (parameters
->options().now())
4247 flags
|= elfcpp::DF_BIND_NOW
;
4249 odyn
->add_constant(elfcpp::DT_FLAGS
, flags
);
4252 if (parameters
->options().initfirst())
4253 flags
|= elfcpp::DF_1_INITFIRST
;
4254 if (parameters
->options().interpose())
4255 flags
|= elfcpp::DF_1_INTERPOSE
;
4256 if (parameters
->options().loadfltr())
4257 flags
|= elfcpp::DF_1_LOADFLTR
;
4258 if (parameters
->options().nodefaultlib())
4259 flags
|= elfcpp::DF_1_NODEFLIB
;
4260 if (parameters
->options().nodelete())
4261 flags
|= elfcpp::DF_1_NODELETE
;
4262 if (parameters
->options().nodlopen())
4263 flags
|= elfcpp::DF_1_NOOPEN
;
4264 if (parameters
->options().nodump())
4265 flags
|= elfcpp::DF_1_NODUMP
;
4266 if (!parameters
->options().shared())
4267 flags
&= ~(elfcpp::DF_1_INITFIRST
4268 | elfcpp::DF_1_NODELETE
4269 | elfcpp::DF_1_NOOPEN
);
4270 if (parameters
->options().origin())
4271 flags
|= elfcpp::DF_1_ORIGIN
;
4272 if (parameters
->options().now())
4273 flags
|= elfcpp::DF_1_NOW
;
4275 odyn
->add_constant(elfcpp::DT_FLAGS_1
, flags
);
4278 // Set the size of the _DYNAMIC symbol table to be the size of the
4282 Layout::set_dynamic_symbol_size(const Symbol_table
* symtab
)
4284 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
4285 odyn
->finalize_data_size();
4286 off_t data_size
= odyn
->data_size();
4287 const int size
= parameters
->target().get_size();
4289 symtab
->get_sized_symbol
<32>(this->dynamic_symbol_
)->set_symsize(data_size
);
4290 else if (size
== 64)
4291 symtab
->get_sized_symbol
<64>(this->dynamic_symbol_
)->set_symsize(data_size
);
4296 // The mapping of input section name prefixes to output section names.
4297 // In some cases one prefix is itself a prefix of another prefix; in
4298 // such a case the longer prefix must come first. These prefixes are
4299 // based on the GNU linker default ELF linker script.
4301 #define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 }
4302 const Layout::Section_name_mapping
Layout::section_name_mapping
[] =
4304 MAPPING_INIT(".text.", ".text"),
4305 MAPPING_INIT(".rodata.", ".rodata"),
4306 MAPPING_INIT(".data.rel.ro.local", ".data.rel.ro.local"),
4307 MAPPING_INIT(".data.rel.ro", ".data.rel.ro"),
4308 MAPPING_INIT(".data.", ".data"),
4309 MAPPING_INIT(".bss.", ".bss"),
4310 MAPPING_INIT(".tdata.", ".tdata"),
4311 MAPPING_INIT(".tbss.", ".tbss"),
4312 MAPPING_INIT(".init_array.", ".init_array"),
4313 MAPPING_INIT(".fini_array.", ".fini_array"),
4314 MAPPING_INIT(".sdata.", ".sdata"),
4315 MAPPING_INIT(".sbss.", ".sbss"),
4316 // FIXME: In the GNU linker, .sbss2 and .sdata2 are handled
4317 // differently depending on whether it is creating a shared library.
4318 MAPPING_INIT(".sdata2.", ".sdata"),
4319 MAPPING_INIT(".sbss2.", ".sbss"),
4320 MAPPING_INIT(".lrodata.", ".lrodata"),
4321 MAPPING_INIT(".ldata.", ".ldata"),
4322 MAPPING_INIT(".lbss.", ".lbss"),
4323 MAPPING_INIT(".gcc_except_table.", ".gcc_except_table"),
4324 MAPPING_INIT(".gnu.linkonce.d.rel.ro.local.", ".data.rel.ro.local"),
4325 MAPPING_INIT(".gnu.linkonce.d.rel.ro.", ".data.rel.ro"),
4326 MAPPING_INIT(".gnu.linkonce.t.", ".text"),
4327 MAPPING_INIT(".gnu.linkonce.r.", ".rodata"),
4328 MAPPING_INIT(".gnu.linkonce.d.", ".data"),
4329 MAPPING_INIT(".gnu.linkonce.b.", ".bss"),
4330 MAPPING_INIT(".gnu.linkonce.s.", ".sdata"),
4331 MAPPING_INIT(".gnu.linkonce.sb.", ".sbss"),
4332 MAPPING_INIT(".gnu.linkonce.s2.", ".sdata"),
4333 MAPPING_INIT(".gnu.linkonce.sb2.", ".sbss"),
4334 MAPPING_INIT(".gnu.linkonce.wi.", ".debug_info"),
4335 MAPPING_INIT(".gnu.linkonce.td.", ".tdata"),
4336 MAPPING_INIT(".gnu.linkonce.tb.", ".tbss"),
4337 MAPPING_INIT(".gnu.linkonce.lr.", ".lrodata"),
4338 MAPPING_INIT(".gnu.linkonce.l.", ".ldata"),
4339 MAPPING_INIT(".gnu.linkonce.lb.", ".lbss"),
4340 MAPPING_INIT(".ARM.extab", ".ARM.extab"),
4341 MAPPING_INIT(".gnu.linkonce.armextab.", ".ARM.extab"),
4342 MAPPING_INIT(".ARM.exidx", ".ARM.exidx"),
4343 MAPPING_INIT(".gnu.linkonce.armexidx.", ".ARM.exidx"),
4347 const int Layout::section_name_mapping_count
=
4348 (sizeof(Layout::section_name_mapping
)
4349 / sizeof(Layout::section_name_mapping
[0]));
4351 // Choose the output section name to use given an input section name.
4352 // Set *PLEN to the length of the name. *PLEN is initialized to the
4356 Layout::output_section_name(const Relobj
* relobj
, const char* name
,
4359 // gcc 4.3 generates the following sorts of section names when it
4360 // needs a section name specific to a function:
4366 // .data.rel.local.FN
4368 // .data.rel.ro.local.FN
4375 // The GNU linker maps all of those to the part before the .FN,
4376 // except that .data.rel.local.FN is mapped to .data, and
4377 // .data.rel.ro.local.FN is mapped to .data.rel.ro. The sections
4378 // beginning with .data.rel.ro.local are grouped together.
4380 // For an anonymous namespace, the string FN can contain a '.'.
4382 // Also of interest: .rodata.strN.N, .rodata.cstN, both of which the
4383 // GNU linker maps to .rodata.
4385 // The .data.rel.ro sections are used with -z relro. The sections
4386 // are recognized by name. We use the same names that the GNU
4387 // linker does for these sections.
4389 // It is hard to handle this in a principled way, so we don't even
4390 // try. We use a table of mappings. If the input section name is
4391 // not found in the table, we simply use it as the output section
4394 const Section_name_mapping
* psnm
= section_name_mapping
;
4395 for (int i
= 0; i
< section_name_mapping_count
; ++i
, ++psnm
)
4397 if (strncmp(name
, psnm
->from
, psnm
->fromlen
) == 0)
4399 *plen
= psnm
->tolen
;
4404 // As an additional complication, .ctors sections are output in
4405 // either .ctors or .init_array sections, and .dtors sections are
4406 // output in either .dtors or .fini_array sections.
4407 if (is_prefix_of(".ctors.", name
) || is_prefix_of(".dtors.", name
))
4409 if (parameters
->options().ctors_in_init_array())
4412 return name
[1] == 'c' ? ".init_array" : ".fini_array";
4417 return name
[1] == 'c' ? ".ctors" : ".dtors";
4420 if (parameters
->options().ctors_in_init_array()
4421 && (strcmp(name
, ".ctors") == 0 || strcmp(name
, ".dtors") == 0))
4423 // To make .init_array/.fini_array work with gcc we must exclude
4424 // .ctors and .dtors sections from the crtbegin and crtend
4427 || (!Layout::match_file_name(relobj
, "crtbegin")
4428 && !Layout::match_file_name(relobj
, "crtend")))
4431 return name
[1] == 'c' ? ".init_array" : ".fini_array";
4438 // Return true if RELOBJ is an input file whose base name matches
4439 // FILE_NAME. The base name must have an extension of ".o", and must
4440 // be exactly FILE_NAME.o or FILE_NAME, one character, ".o". This is
4441 // to match crtbegin.o as well as crtbeginS.o without getting confused
4442 // by other possibilities. Overall matching the file name this way is
4443 // a dreadful hack, but the GNU linker does it in order to better
4444 // support gcc, and we need to be compatible.
4447 Layout::match_file_name(const Relobj
* relobj
, const char* match
)
4449 const std::string
& file_name(relobj
->name());
4450 const char* base_name
= lbasename(file_name
.c_str());
4451 size_t match_len
= strlen(match
);
4452 if (strncmp(base_name
, match
, match_len
) != 0)
4454 size_t base_len
= strlen(base_name
);
4455 if (base_len
!= match_len
+ 2 && base_len
!= match_len
+ 3)
4457 return memcmp(base_name
+ base_len
- 2, ".o", 2) == 0;
4460 // Check if a comdat group or .gnu.linkonce section with the given
4461 // NAME is selected for the link. If there is already a section,
4462 // *KEPT_SECTION is set to point to the existing section and the
4463 // function returns false. Otherwise, OBJECT, SHNDX, IS_COMDAT, and
4464 // IS_GROUP_NAME are recorded for this NAME in the layout object,
4465 // *KEPT_SECTION is set to the internal copy and the function returns
4469 Layout::find_or_add_kept_section(const std::string
& name
,
4474 Kept_section
** kept_section
)
4476 // It's normal to see a couple of entries here, for the x86 thunk
4477 // sections. If we see more than a few, we're linking a C++
4478 // program, and we resize to get more space to minimize rehashing.
4479 if (this->signatures_
.size() > 4
4480 && !this->resized_signatures_
)
4482 reserve_unordered_map(&this->signatures_
,
4483 this->number_of_input_files_
* 64);
4484 this->resized_signatures_
= true;
4487 Kept_section candidate
;
4488 std::pair
<Signatures::iterator
, bool> ins
=
4489 this->signatures_
.insert(std::make_pair(name
, candidate
));
4491 if (kept_section
!= NULL
)
4492 *kept_section
= &ins
.first
->second
;
4495 // This is the first time we've seen this signature.
4496 ins
.first
->second
.set_object(object
);
4497 ins
.first
->second
.set_shndx(shndx
);
4499 ins
.first
->second
.set_is_comdat();
4501 ins
.first
->second
.set_is_group_name();
4505 // We have already seen this signature.
4507 if (ins
.first
->second
.is_group_name())
4509 // We've already seen a real section group with this signature.
4510 // If the kept group is from a plugin object, and we're in the
4511 // replacement phase, accept the new one as a replacement.
4512 if (ins
.first
->second
.object() == NULL
4513 && parameters
->options().plugins()->in_replacement_phase())
4515 ins
.first
->second
.set_object(object
);
4516 ins
.first
->second
.set_shndx(shndx
);
4521 else if (is_group_name
)
4523 // This is a real section group, and we've already seen a
4524 // linkonce section with this signature. Record that we've seen
4525 // a section group, and don't include this section group.
4526 ins
.first
->second
.set_is_group_name();
4531 // We've already seen a linkonce section and this is a linkonce
4532 // section. These don't block each other--this may be the same
4533 // symbol name with different section types.
4538 // Store the allocated sections into the section list.
4541 Layout::get_allocated_sections(Section_list
* section_list
) const
4543 for (Section_list::const_iterator p
= this->section_list_
.begin();
4544 p
!= this->section_list_
.end();
4546 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) != 0)
4547 section_list
->push_back(*p
);
4550 // Create an output segment.
4553 Layout::make_output_segment(elfcpp::Elf_Word type
, elfcpp::Elf_Word flags
)
4555 gold_assert(!parameters
->options().relocatable());
4556 Output_segment
* oseg
= new Output_segment(type
, flags
);
4557 this->segment_list_
.push_back(oseg
);
4559 if (type
== elfcpp::PT_TLS
)
4560 this->tls_segment_
= oseg
;
4561 else if (type
== elfcpp::PT_GNU_RELRO
)
4562 this->relro_segment_
= oseg
;
4563 else if (type
== elfcpp::PT_INTERP
)
4564 this->interp_segment_
= oseg
;
4569 // Return the file offset of the normal symbol table.
4572 Layout::symtab_section_offset() const
4574 if (this->symtab_section_
!= NULL
)
4575 return this->symtab_section_
->offset();
4579 // Return the section index of the normal symbol table. It may have
4580 // been stripped by the -s/--strip-all option.
4583 Layout::symtab_section_shndx() const
4585 if (this->symtab_section_
!= NULL
)
4586 return this->symtab_section_
->out_shndx();
4590 // Write out the Output_sections. Most won't have anything to write,
4591 // since most of the data will come from input sections which are
4592 // handled elsewhere. But some Output_sections do have Output_data.
4595 Layout::write_output_sections(Output_file
* of
) const
4597 for (Section_list::const_iterator p
= this->section_list_
.begin();
4598 p
!= this->section_list_
.end();
4601 if (!(*p
)->after_input_sections())
4606 // Write out data not associated with a section or the symbol table.
4609 Layout::write_data(const Symbol_table
* symtab
, Output_file
* of
) const
4611 if (!parameters
->options().strip_all())
4613 const Output_section
* symtab_section
= this->symtab_section_
;
4614 for (Section_list::const_iterator p
= this->section_list_
.begin();
4615 p
!= this->section_list_
.end();
4618 if ((*p
)->needs_symtab_index())
4620 gold_assert(symtab_section
!= NULL
);
4621 unsigned int index
= (*p
)->symtab_index();
4622 gold_assert(index
> 0 && index
!= -1U);
4623 off_t off
= (symtab_section
->offset()
4624 + index
* symtab_section
->entsize());
4625 symtab
->write_section_symbol(*p
, this->symtab_xindex_
, of
, off
);
4630 const Output_section
* dynsym_section
= this->dynsym_section_
;
4631 for (Section_list::const_iterator p
= this->section_list_
.begin();
4632 p
!= this->section_list_
.end();
4635 if ((*p
)->needs_dynsym_index())
4637 gold_assert(dynsym_section
!= NULL
);
4638 unsigned int index
= (*p
)->dynsym_index();
4639 gold_assert(index
> 0 && index
!= -1U);
4640 off_t off
= (dynsym_section
->offset()
4641 + index
* dynsym_section
->entsize());
4642 symtab
->write_section_symbol(*p
, this->dynsym_xindex_
, of
, off
);
4646 // Write out the Output_data which are not in an Output_section.
4647 for (Data_list::const_iterator p
= this->special_output_list_
.begin();
4648 p
!= this->special_output_list_
.end();
4653 // Write out the Output_sections which can only be written after the
4654 // input sections are complete.
4657 Layout::write_sections_after_input_sections(Output_file
* of
)
4659 // Determine the final section offsets, and thus the final output
4660 // file size. Note we finalize the .shstrab last, to allow the
4661 // after_input_section sections to modify their section-names before
4663 if (this->any_postprocessing_sections_
)
4665 off_t off
= this->output_file_size_
;
4666 off
= this->set_section_offsets(off
, POSTPROCESSING_SECTIONS_PASS
);
4668 // Now that we've finalized the names, we can finalize the shstrab.
4670 this->set_section_offsets(off
,
4671 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
);
4673 if (off
> this->output_file_size_
)
4676 this->output_file_size_
= off
;
4680 for (Section_list::const_iterator p
= this->section_list_
.begin();
4681 p
!= this->section_list_
.end();
4684 if ((*p
)->after_input_sections())
4688 this->section_headers_
->write(of
);
4691 // If the build ID requires computing a checksum, do so here, and
4692 // write it out. We compute a checksum over the entire file because
4693 // that is simplest.
4696 Layout::write_build_id(Output_file
* of
) const
4698 if (this->build_id_note_
== NULL
)
4701 const unsigned char* iv
= of
->get_input_view(0, this->output_file_size_
);
4703 unsigned char* ov
= of
->get_output_view(this->build_id_note_
->offset(),
4704 this->build_id_note_
->data_size());
4706 const char* style
= parameters
->options().build_id();
4707 if (strcmp(style
, "sha1") == 0)
4710 sha1_init_ctx(&ctx
);
4711 sha1_process_bytes(iv
, this->output_file_size_
, &ctx
);
4712 sha1_finish_ctx(&ctx
, ov
);
4714 else if (strcmp(style
, "md5") == 0)
4718 md5_process_bytes(iv
, this->output_file_size_
, &ctx
);
4719 md5_finish_ctx(&ctx
, ov
);
4724 of
->write_output_view(this->build_id_note_
->offset(),
4725 this->build_id_note_
->data_size(),
4728 of
->free_input_view(0, this->output_file_size_
, iv
);
4731 // Write out a binary file. This is called after the link is
4732 // complete. IN is the temporary output file we used to generate the
4733 // ELF code. We simply walk through the segments, read them from
4734 // their file offset in IN, and write them to their load address in
4735 // the output file. FIXME: with a bit more work, we could support
4736 // S-records and/or Intel hex format here.
4739 Layout::write_binary(Output_file
* in
) const
4741 gold_assert(parameters
->options().oformat_enum()
4742 == General_options::OBJECT_FORMAT_BINARY
);
4744 // Get the size of the binary file.
4745 uint64_t max_load_address
= 0;
4746 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
4747 p
!= this->segment_list_
.end();
4750 if ((*p
)->type() == elfcpp::PT_LOAD
&& (*p
)->filesz() > 0)
4752 uint64_t max_paddr
= (*p
)->paddr() + (*p
)->filesz();
4753 if (max_paddr
> max_load_address
)
4754 max_load_address
= max_paddr
;
4758 Output_file
out(parameters
->options().output_file_name());
4759 out
.open(max_load_address
);
4761 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
4762 p
!= this->segment_list_
.end();
4765 if ((*p
)->type() == elfcpp::PT_LOAD
&& (*p
)->filesz() > 0)
4767 const unsigned char* vin
= in
->get_input_view((*p
)->offset(),
4769 unsigned char* vout
= out
.get_output_view((*p
)->paddr(),
4771 memcpy(vout
, vin
, (*p
)->filesz());
4772 out
.write_output_view((*p
)->paddr(), (*p
)->filesz(), vout
);
4773 in
->free_input_view((*p
)->offset(), (*p
)->filesz(), vin
);
4780 // Print the output sections to the map file.
4783 Layout::print_to_mapfile(Mapfile
* mapfile
) const
4785 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
4786 p
!= this->segment_list_
.end();
4788 (*p
)->print_sections_to_mapfile(mapfile
);
4791 // Print statistical information to stderr. This is used for --stats.
4794 Layout::print_stats() const
4796 this->namepool_
.print_stats("section name pool");
4797 this->sympool_
.print_stats("output symbol name pool");
4798 this->dynpool_
.print_stats("dynamic name pool");
4800 for (Section_list::const_iterator p
= this->section_list_
.begin();
4801 p
!= this->section_list_
.end();
4803 (*p
)->print_merge_stats();
4806 // Write_sections_task methods.
4808 // We can always run this task.
4811 Write_sections_task::is_runnable()
4816 // We need to unlock both OUTPUT_SECTIONS_BLOCKER and FINAL_BLOCKER
4820 Write_sections_task::locks(Task_locker
* tl
)
4822 tl
->add(this, this->output_sections_blocker_
);
4823 tl
->add(this, this->final_blocker_
);
4826 // Run the task--write out the data.
4829 Write_sections_task::run(Workqueue
*)
4831 this->layout_
->write_output_sections(this->of_
);
4834 // Write_data_task methods.
4836 // We can always run this task.
4839 Write_data_task::is_runnable()
4844 // We need to unlock FINAL_BLOCKER when finished.
4847 Write_data_task::locks(Task_locker
* tl
)
4849 tl
->add(this, this->final_blocker_
);
4852 // Run the task--write out the data.
4855 Write_data_task::run(Workqueue
*)
4857 this->layout_
->write_data(this->symtab_
, this->of_
);
4860 // Write_symbols_task methods.
4862 // We can always run this task.
4865 Write_symbols_task::is_runnable()
4870 // We need to unlock FINAL_BLOCKER when finished.
4873 Write_symbols_task::locks(Task_locker
* tl
)
4875 tl
->add(this, this->final_blocker_
);
4878 // Run the task--write out the symbols.
4881 Write_symbols_task::run(Workqueue
*)
4883 this->symtab_
->write_globals(this->sympool_
, this->dynpool_
,
4884 this->layout_
->symtab_xindex(),
4885 this->layout_
->dynsym_xindex(), this->of_
);
4888 // Write_after_input_sections_task methods.
4890 // We can only run this task after the input sections have completed.
4893 Write_after_input_sections_task::is_runnable()
4895 if (this->input_sections_blocker_
->is_blocked())
4896 return this->input_sections_blocker_
;
4900 // We need to unlock FINAL_BLOCKER when finished.
4903 Write_after_input_sections_task::locks(Task_locker
* tl
)
4905 tl
->add(this, this->final_blocker_
);
4911 Write_after_input_sections_task::run(Workqueue
*)
4913 this->layout_
->write_sections_after_input_sections(this->of_
);
4916 // Close_task_runner methods.
4918 // Run the task--close the file.
4921 Close_task_runner::run(Workqueue
*, const Task
*)
4923 // If we need to compute a checksum for the BUILD if, we do so here.
4924 this->layout_
->write_build_id(this->of_
);
4926 // If we've been asked to create a binary file, we do so here.
4927 if (this->options_
->oformat_enum() != General_options::OBJECT_FORMAT_ELF
)
4928 this->layout_
->write_binary(this->of_
);
4933 // Instantiate the templates we need. We could use the configure
4934 // script to restrict this to only the ones for implemented targets.
4936 #ifdef HAVE_TARGET_32_LITTLE
4939 Layout::init_fixed_output_section
<32, false>(
4941 elfcpp::Shdr
<32, false>& shdr
);
4944 #ifdef HAVE_TARGET_32_BIG
4947 Layout::init_fixed_output_section
<32, true>(
4949 elfcpp::Shdr
<32, true>& shdr
);
4952 #ifdef HAVE_TARGET_64_LITTLE
4955 Layout::init_fixed_output_section
<64, false>(
4957 elfcpp::Shdr
<64, false>& shdr
);
4960 #ifdef HAVE_TARGET_64_BIG
4963 Layout::init_fixed_output_section
<64, true>(
4965 elfcpp::Shdr
<64, true>& shdr
);
4968 #ifdef HAVE_TARGET_32_LITTLE
4971 Layout::layout
<32, false>(Sized_relobj_file
<32, false>* object
,
4974 const elfcpp::Shdr
<32, false>& shdr
,
4975 unsigned int, unsigned int, off_t
*);
4978 #ifdef HAVE_TARGET_32_BIG
4981 Layout::layout
<32, true>(Sized_relobj_file
<32, true>* object
,
4984 const elfcpp::Shdr
<32, true>& shdr
,
4985 unsigned int, unsigned int, off_t
*);
4988 #ifdef HAVE_TARGET_64_LITTLE
4991 Layout::layout
<64, false>(Sized_relobj_file
<64, false>* object
,
4994 const elfcpp::Shdr
<64, false>& shdr
,
4995 unsigned int, unsigned int, off_t
*);
4998 #ifdef HAVE_TARGET_64_BIG
5001 Layout::layout
<64, true>(Sized_relobj_file
<64, true>* object
,
5004 const elfcpp::Shdr
<64, true>& shdr
,
5005 unsigned int, unsigned int, off_t
*);
5008 #ifdef HAVE_TARGET_32_LITTLE
5011 Layout::layout_reloc
<32, false>(Sized_relobj_file
<32, false>* object
,
5012 unsigned int reloc_shndx
,
5013 const elfcpp::Shdr
<32, false>& shdr
,
5014 Output_section
* data_section
,
5015 Relocatable_relocs
* rr
);
5018 #ifdef HAVE_TARGET_32_BIG
5021 Layout::layout_reloc
<32, true>(Sized_relobj_file
<32, true>* object
,
5022 unsigned int reloc_shndx
,
5023 const elfcpp::Shdr
<32, true>& shdr
,
5024 Output_section
* data_section
,
5025 Relocatable_relocs
* rr
);
5028 #ifdef HAVE_TARGET_64_LITTLE
5031 Layout::layout_reloc
<64, false>(Sized_relobj_file
<64, false>* object
,
5032 unsigned int reloc_shndx
,
5033 const elfcpp::Shdr
<64, false>& shdr
,
5034 Output_section
* data_section
,
5035 Relocatable_relocs
* rr
);
5038 #ifdef HAVE_TARGET_64_BIG
5041 Layout::layout_reloc
<64, true>(Sized_relobj_file
<64, true>* object
,
5042 unsigned int reloc_shndx
,
5043 const elfcpp::Shdr
<64, true>& shdr
,
5044 Output_section
* data_section
,
5045 Relocatable_relocs
* rr
);
5048 #ifdef HAVE_TARGET_32_LITTLE
5051 Layout::layout_group
<32, false>(Symbol_table
* symtab
,
5052 Sized_relobj_file
<32, false>* object
,
5054 const char* group_section_name
,
5055 const char* signature
,
5056 const elfcpp::Shdr
<32, false>& shdr
,
5057 elfcpp::Elf_Word flags
,
5058 std::vector
<unsigned int>* shndxes
);
5061 #ifdef HAVE_TARGET_32_BIG
5064 Layout::layout_group
<32, true>(Symbol_table
* symtab
,
5065 Sized_relobj_file
<32, true>* object
,
5067 const char* group_section_name
,
5068 const char* signature
,
5069 const elfcpp::Shdr
<32, true>& shdr
,
5070 elfcpp::Elf_Word flags
,
5071 std::vector
<unsigned int>* shndxes
);
5074 #ifdef HAVE_TARGET_64_LITTLE
5077 Layout::layout_group
<64, false>(Symbol_table
* symtab
,
5078 Sized_relobj_file
<64, false>* object
,
5080 const char* group_section_name
,
5081 const char* signature
,
5082 const elfcpp::Shdr
<64, false>& shdr
,
5083 elfcpp::Elf_Word flags
,
5084 std::vector
<unsigned int>* shndxes
);
5087 #ifdef HAVE_TARGET_64_BIG
5090 Layout::layout_group
<64, true>(Symbol_table
* symtab
,
5091 Sized_relobj_file
<64, true>* object
,
5093 const char* group_section_name
,
5094 const char* signature
,
5095 const elfcpp::Shdr
<64, true>& shdr
,
5096 elfcpp::Elf_Word flags
,
5097 std::vector
<unsigned int>* shndxes
);
5100 #ifdef HAVE_TARGET_32_LITTLE
5103 Layout::layout_eh_frame
<32, false>(Sized_relobj_file
<32, false>* object
,
5104 const unsigned char* symbols
,
5106 const unsigned char* symbol_names
,
5107 off_t symbol_names_size
,
5109 const elfcpp::Shdr
<32, false>& shdr
,
5110 unsigned int reloc_shndx
,
5111 unsigned int reloc_type
,
5115 #ifdef HAVE_TARGET_32_BIG
5118 Layout::layout_eh_frame
<32, true>(Sized_relobj_file
<32, true>* object
,
5119 const unsigned char* symbols
,
5121 const unsigned char* symbol_names
,
5122 off_t symbol_names_size
,
5124 const elfcpp::Shdr
<32, true>& shdr
,
5125 unsigned int reloc_shndx
,
5126 unsigned int reloc_type
,
5130 #ifdef HAVE_TARGET_64_LITTLE
5133 Layout::layout_eh_frame
<64, false>(Sized_relobj_file
<64, false>* object
,
5134 const unsigned char* symbols
,
5136 const unsigned char* symbol_names
,
5137 off_t symbol_names_size
,
5139 const elfcpp::Shdr
<64, false>& shdr
,
5140 unsigned int reloc_shndx
,
5141 unsigned int reloc_type
,
5145 #ifdef HAVE_TARGET_64_BIG
5148 Layout::layout_eh_frame
<64, true>(Sized_relobj_file
<64, true>* object
,
5149 const unsigned char* symbols
,
5151 const unsigned char* symbol_names
,
5152 off_t symbol_names_size
,
5154 const elfcpp::Shdr
<64, true>& shdr
,
5155 unsigned int reloc_shndx
,
5156 unsigned int reloc_type
,
5160 } // End namespace gold.