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
;
171 if (end
> p
->end_
&& p
->end_
== this->length_
&& this->extend_
)
178 if (p
->start_
+ 3 >= start
&& p
->end_
<= end
+ 3)
179 this->list_
.erase(p
);
180 else if (p
->start_
+ 3 >= start
)
182 else if (p
->end_
<= end
+ 3)
186 Free_list_node
newnode(p
->start_
, start
);
188 this->list_
.insert(p
, newnode
);
189 ++Free_list::num_nodes
;
196 off_t start
= align_address(this->length_
, align
);
197 this->length_
= start
+ len
;
203 // Dump the free list (for debugging).
207 gold_info("Free list:\n start end length\n");
208 for (Iterator p
= this->list_
.begin(); p
!= this->list_
.end(); ++p
)
209 gold_info(" %08lx %08lx %08lx", static_cast<long>(p
->start_
),
210 static_cast<long>(p
->end_
),
211 static_cast<long>(p
->end_
- p
->start_
));
214 // Print the statistics for the free lists.
216 Free_list::print_stats()
218 fprintf(stderr
, _("%s: total free lists: %u\n"),
219 program_name
, Free_list::num_lists
);
220 fprintf(stderr
, _("%s: total free list nodes: %u\n"),
221 program_name
, Free_list::num_nodes
);
222 fprintf(stderr
, _("%s: calls to Free_list::remove: %u\n"),
223 program_name
, Free_list::num_removes
);
224 fprintf(stderr
, _("%s: nodes visited: %u\n"),
225 program_name
, Free_list::num_remove_visits
);
226 fprintf(stderr
, _("%s: calls to Free_list::allocate: %u\n"),
227 program_name
, Free_list::num_allocates
);
228 fprintf(stderr
, _("%s: nodes visited: %u\n"),
229 program_name
, Free_list::num_allocate_visits
);
232 // Layout::Relaxation_debug_check methods.
234 // Check that sections and special data are in reset states.
235 // We do not save states for Output_sections and special Output_data.
236 // So we check that they have not assigned any addresses or offsets.
237 // clean_up_after_relaxation simply resets their addresses and offsets.
239 Layout::Relaxation_debug_check::check_output_data_for_reset_values(
240 const Layout::Section_list
& sections
,
241 const Layout::Data_list
& special_outputs
)
243 for(Layout::Section_list::const_iterator p
= sections
.begin();
246 gold_assert((*p
)->address_and_file_offset_have_reset_values());
248 for(Layout::Data_list::const_iterator p
= special_outputs
.begin();
249 p
!= special_outputs
.end();
251 gold_assert((*p
)->address_and_file_offset_have_reset_values());
254 // Save information of SECTIONS for checking later.
257 Layout::Relaxation_debug_check::read_sections(
258 const Layout::Section_list
& sections
)
260 for(Layout::Section_list::const_iterator p
= sections
.begin();
264 Output_section
* os
= *p
;
266 info
.output_section
= os
;
267 info
.address
= os
->is_address_valid() ? os
->address() : 0;
268 info
.data_size
= os
->is_data_size_valid() ? os
->data_size() : -1;
269 info
.offset
= os
->is_offset_valid()? os
->offset() : -1 ;
270 this->section_infos_
.push_back(info
);
274 // Verify SECTIONS using previously recorded information.
277 Layout::Relaxation_debug_check::verify_sections(
278 const Layout::Section_list
& sections
)
281 for(Layout::Section_list::const_iterator p
= sections
.begin();
285 Output_section
* os
= *p
;
286 uint64_t address
= os
->is_address_valid() ? os
->address() : 0;
287 off_t data_size
= os
->is_data_size_valid() ? os
->data_size() : -1;
288 off_t offset
= os
->is_offset_valid()? os
->offset() : -1 ;
290 if (i
>= this->section_infos_
.size())
292 gold_fatal("Section_info of %s missing.\n", os
->name());
294 const Section_info
& info
= this->section_infos_
[i
];
295 if (os
!= info
.output_section
)
296 gold_fatal("Section order changed. Expecting %s but see %s\n",
297 info
.output_section
->name(), os
->name());
298 if (address
!= info
.address
299 || data_size
!= info
.data_size
300 || offset
!= info
.offset
)
301 gold_fatal("Section %s changed.\n", os
->name());
305 // Layout_task_runner methods.
307 // Lay out the sections. This is called after all the input objects
311 Layout_task_runner::run(Workqueue
* workqueue
, const Task
* task
)
313 Layout
* layout
= this->layout_
;
314 off_t file_size
= layout
->finalize(this->input_objects_
,
319 // Now we know the final size of the output file and we know where
320 // each piece of information goes.
322 if (this->mapfile_
!= NULL
)
324 this->mapfile_
->print_discarded_sections(this->input_objects_
);
325 layout
->print_to_mapfile(this->mapfile_
);
329 if (layout
->incremental_base() == NULL
)
331 of
= new Output_file(parameters
->options().output_file_name());
332 if (this->options_
.oformat_enum() != General_options::OBJECT_FORMAT_ELF
)
333 of
->set_is_temporary();
338 of
= layout
->incremental_base()->output_file();
340 // Apply the incremental relocations for symbols whose values
341 // have changed. We do this before we resize the file and start
342 // writing anything else to it, so that we can read the old
343 // incremental information from the file before (possibly)
345 if (parameters
->incremental_update())
346 layout
->incremental_base()->apply_incremental_relocs(this->symtab_
,
350 of
->resize(file_size
);
353 // Queue up the final set of tasks.
354 gold::queue_final_tasks(this->options_
, this->input_objects_
,
355 this->symtab_
, layout
, workqueue
, of
);
360 Layout::Layout(int number_of_input_files
, Script_options
* script_options
)
361 : number_of_input_files_(number_of_input_files
),
362 script_options_(script_options
),
370 unattached_section_list_(),
371 special_output_list_(),
372 section_headers_(NULL
),
374 relro_segment_(NULL
),
375 interp_segment_(NULL
),
377 symtab_section_(NULL
),
378 symtab_xindex_(NULL
),
379 dynsym_section_(NULL
),
380 dynsym_xindex_(NULL
),
381 dynamic_section_(NULL
),
382 dynamic_symbol_(NULL
),
384 eh_frame_section_(NULL
),
385 eh_frame_data_(NULL
),
386 added_eh_frame_data_(false),
387 eh_frame_hdr_section_(NULL
),
388 build_id_note_(NULL
),
392 output_file_size_(-1),
393 have_added_input_section_(false),
394 sections_are_attached_(false),
395 input_requires_executable_stack_(false),
396 input_with_gnu_stack_note_(false),
397 input_without_gnu_stack_note_(false),
398 has_static_tls_(false),
399 any_postprocessing_sections_(false),
400 resized_signatures_(false),
401 have_stabstr_section_(false),
402 incremental_inputs_(NULL
),
403 record_output_section_data_from_script_(false),
404 script_output_section_data_list_(),
405 segment_states_(NULL
),
406 relaxation_debug_check_(NULL
),
407 incremental_base_(NULL
),
410 // Make space for more than enough segments for a typical file.
411 // This is just for efficiency--it's OK if we wind up needing more.
412 this->segment_list_
.reserve(12);
414 // We expect two unattached Output_data objects: the file header and
415 // the segment headers.
416 this->special_output_list_
.reserve(2);
418 // Initialize structure needed for an incremental build.
419 if (parameters
->incremental())
420 this->incremental_inputs_
= new Incremental_inputs
;
422 // The section name pool is worth optimizing in all cases, because
423 // it is small, but there are often overlaps due to .rel sections.
424 this->namepool_
.set_optimize();
427 // For incremental links, record the base file to be modified.
430 Layout::set_incremental_base(Incremental_binary
* base
)
432 this->incremental_base_
= base
;
433 this->free_list_
.init(base
->output_file()->filesize(), true);
436 // Hash a key we use to look up an output section mapping.
439 Layout::Hash_key::operator()(const Layout::Key
& k
) const
441 return k
.first
+ k
.second
.first
+ k
.second
.second
;
444 // Returns whether the given section is in the list of
445 // debug-sections-used-by-some-version-of-gdb. Currently,
446 // we've checked versions of gdb up to and including 6.7.1.
448 static const char* gdb_sections
[] =
450 // ".debug_aranges", // not used by gdb as of 6.7.1
457 // ".debug_pubnames", // not used by gdb as of 6.7.1
462 static const char* lines_only_debug_sections
[] =
464 // ".debug_aranges", // not used by gdb as of 6.7.1
471 // ".debug_pubnames", // not used by gdb as of 6.7.1
477 is_gdb_debug_section(const char* str
)
479 // We can do this faster: binary search or a hashtable. But why bother?
480 for (size_t i
= 0; i
< sizeof(gdb_sections
)/sizeof(*gdb_sections
); ++i
)
481 if (strcmp(str
, gdb_sections
[i
]) == 0)
487 is_lines_only_debug_section(const char* str
)
489 // We can do this faster: binary search or a hashtable. But why bother?
491 i
< sizeof(lines_only_debug_sections
)/sizeof(*lines_only_debug_sections
);
493 if (strcmp(str
, lines_only_debug_sections
[i
]) == 0)
498 // Sometimes we compress sections. This is typically done for
499 // sections that are not part of normal program execution (such as
500 // .debug_* sections), and where the readers of these sections know
501 // how to deal with compressed sections. This routine doesn't say for
502 // certain whether we'll compress -- it depends on commandline options
503 // as well -- just whether this section is a candidate for compression.
504 // (The Output_compressed_section class decides whether to compress
505 // a given section, and picks the name of the compressed section.)
508 is_compressible_debug_section(const char* secname
)
510 return (is_prefix_of(".debug", secname
));
513 // We may see compressed debug sections in input files. Return TRUE
514 // if this is the name of a compressed debug section.
517 is_compressed_debug_section(const char* secname
)
519 return (is_prefix_of(".zdebug", secname
));
522 // Whether to include this section in the link.
524 template<int size
, bool big_endian
>
526 Layout::include_section(Sized_relobj_file
<size
, big_endian
>*, const char* name
,
527 const elfcpp::Shdr
<size
, big_endian
>& shdr
)
529 if (shdr
.get_sh_flags() & elfcpp::SHF_EXCLUDE
)
532 switch (shdr
.get_sh_type())
534 case elfcpp::SHT_NULL
:
535 case elfcpp::SHT_SYMTAB
:
536 case elfcpp::SHT_DYNSYM
:
537 case elfcpp::SHT_HASH
:
538 case elfcpp::SHT_DYNAMIC
:
539 case elfcpp::SHT_SYMTAB_SHNDX
:
542 case elfcpp::SHT_STRTAB
:
543 // Discard the sections which have special meanings in the ELF
544 // ABI. Keep others (e.g., .stabstr). We could also do this by
545 // checking the sh_link fields of the appropriate sections.
546 return (strcmp(name
, ".dynstr") != 0
547 && strcmp(name
, ".strtab") != 0
548 && strcmp(name
, ".shstrtab") != 0);
550 case elfcpp::SHT_RELA
:
551 case elfcpp::SHT_REL
:
552 case elfcpp::SHT_GROUP
:
553 // If we are emitting relocations these should be handled
555 gold_assert(!parameters
->options().relocatable()
556 && !parameters
->options().emit_relocs());
559 case elfcpp::SHT_PROGBITS
:
560 if (parameters
->options().strip_debug()
561 && (shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) == 0)
563 if (is_debug_info_section(name
))
566 if (parameters
->options().strip_debug_non_line()
567 && (shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) == 0)
569 // Debugging sections can only be recognized by name.
570 if (is_prefix_of(".debug", name
)
571 && !is_lines_only_debug_section(name
))
574 if (parameters
->options().strip_debug_gdb()
575 && (shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) == 0)
577 // Debugging sections can only be recognized by name.
578 if (is_prefix_of(".debug", name
)
579 && !is_gdb_debug_section(name
))
582 if (parameters
->options().strip_lto_sections()
583 && !parameters
->options().relocatable()
584 && (shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) == 0)
586 // Ignore LTO sections containing intermediate code.
587 if (is_prefix_of(".gnu.lto_", name
))
590 // The GNU linker strips .gnu_debuglink sections, so we do too.
591 // This is a feature used to keep debugging information in
593 if (strcmp(name
, ".gnu_debuglink") == 0)
602 // Return an output section named NAME, or NULL if there is none.
605 Layout::find_output_section(const char* name
) const
607 for (Section_list::const_iterator p
= this->section_list_
.begin();
608 p
!= this->section_list_
.end();
610 if (strcmp((*p
)->name(), name
) == 0)
615 // Return an output segment of type TYPE, with segment flags SET set
616 // and segment flags CLEAR clear. Return NULL if there is none.
619 Layout::find_output_segment(elfcpp::PT type
, elfcpp::Elf_Word set
,
620 elfcpp::Elf_Word clear
) const
622 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
623 p
!= this->segment_list_
.end();
625 if (static_cast<elfcpp::PT
>((*p
)->type()) == type
626 && ((*p
)->flags() & set
) == set
627 && ((*p
)->flags() & clear
) == 0)
632 // When we put a .ctors or .dtors section with more than one word into
633 // a .init_array or .fini_array section, we need to reverse the words
634 // in the .ctors/.dtors section. This is because .init_array executes
635 // constructors front to back, where .ctors executes them back to
636 // front, and vice-versa for .fini_array/.dtors. Although we do want
637 // to remap .ctors/.dtors into .init_array/.fini_array because it can
638 // be more efficient, we don't want to change the order in which
639 // constructors/destructors are run. This set just keeps track of
640 // these sections which need to be reversed. It is only changed by
641 // Layout::layout. It should be a private member of Layout, but that
642 // would require layout.h to #include object.h to get the definition
644 static Unordered_set
<Section_id
, Section_id_hash
> ctors_sections_in_init_array
;
646 // Return whether OBJECT/SHNDX is a .ctors/.dtors section mapped to a
647 // .init_array/.fini_array section.
650 Layout::is_ctors_in_init_array(Relobj
* relobj
, unsigned int shndx
) const
652 return (ctors_sections_in_init_array
.find(Section_id(relobj
, shndx
))
653 != ctors_sections_in_init_array
.end());
656 // Return the output section to use for section NAME with type TYPE
657 // and section flags FLAGS. NAME must be canonicalized in the string
658 // pool, and NAME_KEY is the key. ORDER is where this should appear
659 // in the output sections. IS_RELRO is true for a relro section.
662 Layout::get_output_section(const char* name
, Stringpool::Key name_key
,
663 elfcpp::Elf_Word type
, elfcpp::Elf_Xword flags
,
664 Output_section_order order
, bool is_relro
)
666 elfcpp::Elf_Word lookup_type
= type
;
668 // For lookup purposes, treat INIT_ARRAY, FINI_ARRAY, and
669 // PREINIT_ARRAY like PROGBITS. This ensures that we combine
670 // .init_array, .fini_array, and .preinit_array sections by name
671 // whatever their type in the input file. We do this because the
672 // types are not always right in the input files.
673 if (lookup_type
== elfcpp::SHT_INIT_ARRAY
674 || lookup_type
== elfcpp::SHT_FINI_ARRAY
675 || lookup_type
== elfcpp::SHT_PREINIT_ARRAY
)
676 lookup_type
= elfcpp::SHT_PROGBITS
;
678 elfcpp::Elf_Xword lookup_flags
= flags
;
680 // Ignoring SHF_WRITE and SHF_EXECINSTR here means that we combine
681 // read-write with read-only sections. Some other ELF linkers do
682 // not do this. FIXME: Perhaps there should be an option
684 lookup_flags
&= ~(elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
);
686 const Key
key(name_key
, std::make_pair(lookup_type
, lookup_flags
));
687 const std::pair
<Key
, Output_section
*> v(key
, NULL
);
688 std::pair
<Section_name_map::iterator
, bool> ins(
689 this->section_name_map_
.insert(v
));
692 return ins
.first
->second
;
695 // This is the first time we've seen this name/type/flags
696 // combination. For compatibility with the GNU linker, we
697 // combine sections with contents and zero flags with sections
698 // with non-zero flags. This is a workaround for cases where
699 // assembler code forgets to set section flags. FIXME: Perhaps
700 // there should be an option to control this.
701 Output_section
* os
= NULL
;
703 if (lookup_type
== elfcpp::SHT_PROGBITS
)
707 Output_section
* same_name
= this->find_output_section(name
);
708 if (same_name
!= NULL
709 && (same_name
->type() == elfcpp::SHT_PROGBITS
710 || same_name
->type() == elfcpp::SHT_INIT_ARRAY
711 || same_name
->type() == elfcpp::SHT_FINI_ARRAY
712 || same_name
->type() == elfcpp::SHT_PREINIT_ARRAY
)
713 && (same_name
->flags() & elfcpp::SHF_TLS
) == 0)
716 else if ((flags
& elfcpp::SHF_TLS
) == 0)
718 elfcpp::Elf_Xword zero_flags
= 0;
719 const Key
zero_key(name_key
, std::make_pair(lookup_type
,
721 Section_name_map::iterator p
=
722 this->section_name_map_
.find(zero_key
);
723 if (p
!= this->section_name_map_
.end())
729 os
= this->make_output_section(name
, type
, flags
, order
, is_relro
);
731 ins
.first
->second
= os
;
736 // Pick the output section to use for section NAME, in input file
737 // RELOBJ, with type TYPE and flags FLAGS. RELOBJ may be NULL for a
738 // linker created section. IS_INPUT_SECTION is true if we are
739 // choosing an output section for an input section found in a input
740 // file. ORDER is where this section should appear in the output
741 // sections. IS_RELRO is true for a relro section. This will return
742 // NULL if the input section should be discarded.
745 Layout::choose_output_section(const Relobj
* relobj
, const char* name
,
746 elfcpp::Elf_Word type
, elfcpp::Elf_Xword flags
,
747 bool is_input_section
, Output_section_order order
,
750 // We should not see any input sections after we have attached
751 // sections to segments.
752 gold_assert(!is_input_section
|| !this->sections_are_attached_
);
754 // Some flags in the input section should not be automatically
755 // copied to the output section.
756 flags
&= ~ (elfcpp::SHF_INFO_LINK
759 | elfcpp::SHF_STRINGS
);
761 // We only clear the SHF_LINK_ORDER flag in for
762 // a non-relocatable link.
763 if (!parameters
->options().relocatable())
764 flags
&= ~elfcpp::SHF_LINK_ORDER
;
766 if (this->script_options_
->saw_sections_clause())
768 // We are using a SECTIONS clause, so the output section is
769 // chosen based only on the name.
771 Script_sections
* ss
= this->script_options_
->script_sections();
772 const char* file_name
= relobj
== NULL
? NULL
: relobj
->name().c_str();
773 Output_section
** output_section_slot
;
774 Script_sections::Section_type script_section_type
;
775 const char* orig_name
= name
;
776 name
= ss
->output_section_name(file_name
, name
, &output_section_slot
,
777 &script_section_type
);
780 gold_debug(DEBUG_SCRIPT
, _("Unable to create output section '%s' "
781 "because it is not allowed by the "
782 "SECTIONS clause of the linker script"),
784 // The SECTIONS clause says to discard this input section.
788 // We can only handle script section types ST_NONE and ST_NOLOAD.
789 switch (script_section_type
)
791 case Script_sections::ST_NONE
:
793 case Script_sections::ST_NOLOAD
:
794 flags
&= elfcpp::SHF_ALLOC
;
800 // If this is an orphan section--one not mentioned in the linker
801 // script--then OUTPUT_SECTION_SLOT will be NULL, and we do the
802 // default processing below.
804 if (output_section_slot
!= NULL
)
806 if (*output_section_slot
!= NULL
)
808 (*output_section_slot
)->update_flags_for_input_section(flags
);
809 return *output_section_slot
;
812 // We don't put sections found in the linker script into
813 // SECTION_NAME_MAP_. That keeps us from getting confused
814 // if an orphan section is mapped to a section with the same
815 // name as one in the linker script.
817 name
= this->namepool_
.add(name
, false, NULL
);
819 Output_section
* os
= this->make_output_section(name
, type
, flags
,
822 os
->set_found_in_sections_clause();
824 // Special handling for NOLOAD sections.
825 if (script_section_type
== Script_sections::ST_NOLOAD
)
829 // The constructor of Output_section sets addresses of non-ALLOC
830 // sections to 0 by default. We don't want that for NOLOAD
831 // sections even if they have no SHF_ALLOC flag.
832 if ((os
->flags() & elfcpp::SHF_ALLOC
) == 0
833 && os
->is_address_valid())
835 gold_assert(os
->address() == 0
836 && !os
->is_offset_valid()
837 && !os
->is_data_size_valid());
838 os
->reset_address_and_file_offset();
842 *output_section_slot
= os
;
847 // FIXME: Handle SHF_OS_NONCONFORMING somewhere.
849 size_t len
= strlen(name
);
850 char* uncompressed_name
= NULL
;
852 // Compressed debug sections should be mapped to the corresponding
853 // uncompressed section.
854 if (is_compressed_debug_section(name
))
856 uncompressed_name
= new char[len
];
857 uncompressed_name
[0] = '.';
858 gold_assert(name
[0] == '.' && name
[1] == 'z');
859 strncpy(&uncompressed_name
[1], &name
[2], len
- 2);
860 uncompressed_name
[len
- 1] = '\0';
862 name
= uncompressed_name
;
865 // Turn NAME from the name of the input section into the name of the
868 && !this->script_options_
->saw_sections_clause()
869 && !parameters
->options().relocatable())
870 name
= Layout::output_section_name(relobj
, name
, &len
);
872 Stringpool::Key name_key
;
873 name
= this->namepool_
.add_with_length(name
, len
, true, &name_key
);
875 if (uncompressed_name
!= NULL
)
876 delete[] uncompressed_name
;
878 // Find or make the output section. The output section is selected
879 // based on the section name, type, and flags.
880 return this->get_output_section(name
, name_key
, type
, flags
, order
, is_relro
);
883 // For incremental links, record the initial fixed layout of a section
884 // from the base file, and return a pointer to the Output_section.
886 template<int size
, bool big_endian
>
888 Layout::init_fixed_output_section(const char* name
,
889 elfcpp::Shdr
<size
, big_endian
>& shdr
)
891 unsigned int sh_type
= shdr
.get_sh_type();
893 // We preserve the layout of PROGBITS, NOBITS, and NOTE sections.
894 // All others will be created from scratch and reallocated.
895 if (sh_type
!= elfcpp::SHT_PROGBITS
896 && sh_type
!= elfcpp::SHT_NOBITS
897 && sh_type
!= elfcpp::SHT_NOTE
)
900 typename
elfcpp::Elf_types
<size
>::Elf_Addr sh_addr
= shdr
.get_sh_addr();
901 typename
elfcpp::Elf_types
<size
>::Elf_Off sh_offset
= shdr
.get_sh_offset();
902 typename
elfcpp::Elf_types
<size
>::Elf_WXword sh_size
= shdr
.get_sh_size();
903 typename
elfcpp::Elf_types
<size
>::Elf_WXword sh_flags
= shdr
.get_sh_flags();
904 typename
elfcpp::Elf_types
<size
>::Elf_WXword sh_addralign
=
905 shdr
.get_sh_addralign();
907 // Make the output section.
908 Stringpool::Key name_key
;
909 name
= this->namepool_
.add(name
, true, &name_key
);
910 Output_section
* os
= this->get_output_section(name
, name_key
, sh_type
,
911 sh_flags
, ORDER_INVALID
, false);
912 os
->set_fixed_layout(sh_addr
, sh_offset
, sh_size
, sh_addralign
);
913 if (sh_type
!= elfcpp::SHT_NOBITS
)
914 this->free_list_
.remove(sh_offset
, sh_offset
+ sh_size
);
918 // Return the output section to use for input section SHNDX, with name
919 // NAME, with header HEADER, from object OBJECT. RELOC_SHNDX is the
920 // index of a relocation section which applies to this section, or 0
921 // if none, or -1U if more than one. RELOC_TYPE is the type of the
922 // relocation section if there is one. Set *OFF to the offset of this
923 // input section without the output section. Return NULL if the
924 // section should be discarded. Set *OFF to -1 if the section
925 // contents should not be written directly to the output file, but
926 // will instead receive special handling.
928 template<int size
, bool big_endian
>
930 Layout::layout(Sized_relobj_file
<size
, big_endian
>* object
, unsigned int shndx
,
931 const char* name
, const elfcpp::Shdr
<size
, big_endian
>& shdr
,
932 unsigned int reloc_shndx
, unsigned int, off_t
* off
)
936 if (!this->include_section(object
, name
, shdr
))
939 elfcpp::Elf_Word sh_type
= shdr
.get_sh_type();
941 // In a relocatable link a grouped section must not be combined with
942 // any other sections.
944 if (parameters
->options().relocatable()
945 && (shdr
.get_sh_flags() & elfcpp::SHF_GROUP
) != 0)
947 name
= this->namepool_
.add(name
, true, NULL
);
948 os
= this->make_output_section(name
, sh_type
, shdr
.get_sh_flags(),
949 ORDER_INVALID
, false);
953 os
= this->choose_output_section(object
, name
, sh_type
,
954 shdr
.get_sh_flags(), true,
955 ORDER_INVALID
, false);
960 // By default the GNU linker sorts input sections whose names match
961 // .ctors.*, .dtors.*, .init_array.*, or .fini_array.*. The
962 // sections are sorted by name. This is used to implement
963 // constructor priority ordering. We are compatible. When we put
964 // .ctor sections in .init_array and .dtor sections in .fini_array,
965 // we must also sort plain .ctor and .dtor sections.
966 if (!this->script_options_
->saw_sections_clause()
967 && !parameters
->options().relocatable()
968 && (is_prefix_of(".ctors.", name
)
969 || is_prefix_of(".dtors.", name
)
970 || is_prefix_of(".init_array.", name
)
971 || is_prefix_of(".fini_array.", name
)
972 || (parameters
->options().ctors_in_init_array()
973 && (strcmp(name
, ".ctors") == 0
974 || strcmp(name
, ".dtors") == 0))))
975 os
->set_must_sort_attached_input_sections();
977 // If this is a .ctors or .ctors.* section being mapped to a
978 // .init_array section, or a .dtors or .dtors.* section being mapped
979 // to a .fini_array section, we will need to reverse the words if
980 // there is more than one. Record this section for later. See
981 // ctors_sections_in_init_array above.
982 if (!this->script_options_
->saw_sections_clause()
983 && !parameters
->options().relocatable()
984 && shdr
.get_sh_size() > size
/ 8
985 && (((strcmp(name
, ".ctors") == 0
986 || is_prefix_of(".ctors.", name
))
987 && strcmp(os
->name(), ".init_array") == 0)
988 || ((strcmp(name
, ".dtors") == 0
989 || is_prefix_of(".dtors.", name
))
990 && strcmp(os
->name(), ".fini_array") == 0)))
991 ctors_sections_in_init_array
.insert(Section_id(object
, shndx
));
993 // FIXME: Handle SHF_LINK_ORDER somewhere.
995 elfcpp::Elf_Xword orig_flags
= os
->flags();
997 *off
= os
->add_input_section(this, object
, shndx
, name
, shdr
, reloc_shndx
,
998 this->script_options_
->saw_sections_clause());
1000 // If the flags changed, we may have to change the order.
1001 if ((orig_flags
& elfcpp::SHF_ALLOC
) != 0)
1003 orig_flags
&= (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
);
1004 elfcpp::Elf_Xword new_flags
=
1005 os
->flags() & (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
);
1006 if (orig_flags
!= new_flags
)
1007 os
->set_order(this->default_section_order(os
, false));
1010 this->have_added_input_section_
= true;
1015 // Handle a relocation section when doing a relocatable link.
1017 template<int size
, bool big_endian
>
1019 Layout::layout_reloc(Sized_relobj_file
<size
, big_endian
>* object
,
1021 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
1022 Output_section
* data_section
,
1023 Relocatable_relocs
* rr
)
1025 gold_assert(parameters
->options().relocatable()
1026 || parameters
->options().emit_relocs());
1028 int sh_type
= shdr
.get_sh_type();
1031 if (sh_type
== elfcpp::SHT_REL
)
1033 else if (sh_type
== elfcpp::SHT_RELA
)
1037 name
+= data_section
->name();
1039 // In a relocatable link relocs for a grouped section must not be
1040 // combined with other reloc sections.
1042 if (!parameters
->options().relocatable()
1043 || (data_section
->flags() & elfcpp::SHF_GROUP
) == 0)
1044 os
= this->choose_output_section(object
, name
.c_str(), sh_type
,
1045 shdr
.get_sh_flags(), false,
1046 ORDER_INVALID
, false);
1049 const char* n
= this->namepool_
.add(name
.c_str(), true, NULL
);
1050 os
= this->make_output_section(n
, sh_type
, shdr
.get_sh_flags(),
1051 ORDER_INVALID
, false);
1054 os
->set_should_link_to_symtab();
1055 os
->set_info_section(data_section
);
1057 Output_section_data
* posd
;
1058 if (sh_type
== elfcpp::SHT_REL
)
1060 os
->set_entsize(elfcpp::Elf_sizes
<size
>::rel_size
);
1061 posd
= new Output_relocatable_relocs
<elfcpp::SHT_REL
,
1065 else if (sh_type
== elfcpp::SHT_RELA
)
1067 os
->set_entsize(elfcpp::Elf_sizes
<size
>::rela_size
);
1068 posd
= new Output_relocatable_relocs
<elfcpp::SHT_RELA
,
1075 os
->add_output_section_data(posd
);
1076 rr
->set_output_data(posd
);
1081 // Handle a group section when doing a relocatable link.
1083 template<int size
, bool big_endian
>
1085 Layout::layout_group(Symbol_table
* symtab
,
1086 Sized_relobj_file
<size
, big_endian
>* object
,
1088 const char* group_section_name
,
1089 const char* signature
,
1090 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
1091 elfcpp::Elf_Word flags
,
1092 std::vector
<unsigned int>* shndxes
)
1094 gold_assert(parameters
->options().relocatable());
1095 gold_assert(shdr
.get_sh_type() == elfcpp::SHT_GROUP
);
1096 group_section_name
= this->namepool_
.add(group_section_name
, true, NULL
);
1097 Output_section
* os
= this->make_output_section(group_section_name
,
1099 shdr
.get_sh_flags(),
1100 ORDER_INVALID
, false);
1102 // We need to find a symbol with the signature in the symbol table.
1103 // If we don't find one now, we need to look again later.
1104 Symbol
* sym
= symtab
->lookup(signature
, NULL
);
1106 os
->set_info_symndx(sym
);
1109 // Reserve some space to minimize reallocations.
1110 if (this->group_signatures_
.empty())
1111 this->group_signatures_
.reserve(this->number_of_input_files_
* 16);
1113 // We will wind up using a symbol whose name is the signature.
1114 // So just put the signature in the symbol name pool to save it.
1115 signature
= symtab
->canonicalize_name(signature
);
1116 this->group_signatures_
.push_back(Group_signature(os
, signature
));
1119 os
->set_should_link_to_symtab();
1122 section_size_type entry_count
=
1123 convert_to_section_size_type(shdr
.get_sh_size() / 4);
1124 Output_section_data
* posd
=
1125 new Output_data_group
<size
, big_endian
>(object
, entry_count
, flags
,
1127 os
->add_output_section_data(posd
);
1130 // Special GNU handling of sections name .eh_frame. They will
1131 // normally hold exception frame data as defined by the C++ ABI
1132 // (http://codesourcery.com/cxx-abi/).
1134 template<int size
, bool big_endian
>
1136 Layout::layout_eh_frame(Sized_relobj_file
<size
, big_endian
>* object
,
1137 const unsigned char* symbols
,
1139 const unsigned char* symbol_names
,
1140 off_t symbol_names_size
,
1142 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
1143 unsigned int reloc_shndx
, unsigned int reloc_type
,
1146 gold_assert(shdr
.get_sh_type() == elfcpp::SHT_PROGBITS
1147 || shdr
.get_sh_type() == elfcpp::SHT_X86_64_UNWIND
);
1148 gold_assert((shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) != 0);
1150 Output_section
* os
= this->make_eh_frame_section(object
);
1154 gold_assert(this->eh_frame_section_
== os
);
1156 elfcpp::Elf_Xword orig_flags
= os
->flags();
1158 if (!parameters
->incremental()
1159 && this->eh_frame_data_
->add_ehframe_input_section(object
,
1168 os
->update_flags_for_input_section(shdr
.get_sh_flags());
1170 // A writable .eh_frame section is a RELRO section.
1171 if ((orig_flags
& (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
))
1172 != (os
->flags() & (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
)))
1175 os
->set_order(ORDER_RELRO
);
1178 // We found a .eh_frame section we are going to optimize, so now
1179 // we can add the set of optimized sections to the output
1180 // section. We need to postpone adding this until we've found a
1181 // section we can optimize so that the .eh_frame section in
1182 // crtbegin.o winds up at the start of the output section.
1183 if (!this->added_eh_frame_data_
)
1185 os
->add_output_section_data(this->eh_frame_data_
);
1186 this->added_eh_frame_data_
= true;
1192 // We couldn't handle this .eh_frame section for some reason.
1193 // Add it as a normal section.
1194 bool saw_sections_clause
= this->script_options_
->saw_sections_clause();
1195 *off
= os
->add_input_section(this, object
, shndx
, ".eh_frame", shdr
,
1196 reloc_shndx
, saw_sections_clause
);
1197 this->have_added_input_section_
= true;
1199 if ((orig_flags
& (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
))
1200 != (os
->flags() & (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
)))
1201 os
->set_order(this->default_section_order(os
, false));
1207 // Create and return the magic .eh_frame section. Create
1208 // .eh_frame_hdr also if appropriate. OBJECT is the object with the
1209 // input .eh_frame section; it may be NULL.
1212 Layout::make_eh_frame_section(const Relobj
* object
)
1214 // FIXME: On x86_64, this could use SHT_X86_64_UNWIND rather than
1216 Output_section
* os
= this->choose_output_section(object
, ".eh_frame",
1217 elfcpp::SHT_PROGBITS
,
1218 elfcpp::SHF_ALLOC
, false,
1219 ORDER_EHFRAME
, false);
1223 if (this->eh_frame_section_
== NULL
)
1225 this->eh_frame_section_
= os
;
1226 this->eh_frame_data_
= new Eh_frame();
1228 // For incremental linking, we do not optimize .eh_frame sections
1229 // or create a .eh_frame_hdr section.
1230 if (parameters
->options().eh_frame_hdr() && !parameters
->incremental())
1232 Output_section
* hdr_os
=
1233 this->choose_output_section(NULL
, ".eh_frame_hdr",
1234 elfcpp::SHT_PROGBITS
,
1235 elfcpp::SHF_ALLOC
, false,
1236 ORDER_EHFRAME
, false);
1240 Eh_frame_hdr
* hdr_posd
= new Eh_frame_hdr(os
,
1241 this->eh_frame_data_
);
1242 hdr_os
->add_output_section_data(hdr_posd
);
1244 hdr_os
->set_after_input_sections();
1246 if (!this->script_options_
->saw_phdrs_clause())
1248 Output_segment
* hdr_oseg
;
1249 hdr_oseg
= this->make_output_segment(elfcpp::PT_GNU_EH_FRAME
,
1251 hdr_oseg
->add_output_section_to_nonload(hdr_os
,
1255 this->eh_frame_data_
->set_eh_frame_hdr(hdr_posd
);
1263 // Add an exception frame for a PLT. This is called from target code.
1266 Layout::add_eh_frame_for_plt(Output_data
* plt
, const unsigned char* cie_data
,
1267 size_t cie_length
, const unsigned char* fde_data
,
1270 if (parameters
->incremental())
1272 // FIXME: Maybe this could work some day....
1275 Output_section
* os
= this->make_eh_frame_section(NULL
);
1278 this->eh_frame_data_
->add_ehframe_for_plt(plt
, cie_data
, cie_length
,
1279 fde_data
, fde_length
);
1280 if (!this->added_eh_frame_data_
)
1282 os
->add_output_section_data(this->eh_frame_data_
);
1283 this->added_eh_frame_data_
= true;
1287 // Add POSD to an output section using NAME, TYPE, and FLAGS. Return
1288 // the output section.
1291 Layout::add_output_section_data(const char* name
, elfcpp::Elf_Word type
,
1292 elfcpp::Elf_Xword flags
,
1293 Output_section_data
* posd
,
1294 Output_section_order order
, bool is_relro
)
1296 Output_section
* os
= this->choose_output_section(NULL
, name
, type
, flags
,
1297 false, order
, is_relro
);
1299 os
->add_output_section_data(posd
);
1303 // Map section flags to segment flags.
1306 Layout::section_flags_to_segment(elfcpp::Elf_Xword flags
)
1308 elfcpp::Elf_Word ret
= elfcpp::PF_R
;
1309 if ((flags
& elfcpp::SHF_WRITE
) != 0)
1310 ret
|= elfcpp::PF_W
;
1311 if ((flags
& elfcpp::SHF_EXECINSTR
) != 0)
1312 ret
|= elfcpp::PF_X
;
1316 // Make a new Output_section, and attach it to segments as
1317 // appropriate. ORDER is the order in which this section should
1318 // appear in the output segment. IS_RELRO is true if this is a relro
1319 // (read-only after relocations) section.
1322 Layout::make_output_section(const char* name
, elfcpp::Elf_Word type
,
1323 elfcpp::Elf_Xword flags
,
1324 Output_section_order order
, bool is_relro
)
1327 if ((flags
& elfcpp::SHF_ALLOC
) == 0
1328 && strcmp(parameters
->options().compress_debug_sections(), "none") != 0
1329 && is_compressible_debug_section(name
))
1330 os
= new Output_compressed_section(¶meters
->options(), name
, type
,
1332 else if ((flags
& elfcpp::SHF_ALLOC
) == 0
1333 && parameters
->options().strip_debug_non_line()
1334 && strcmp(".debug_abbrev", name
) == 0)
1336 os
= this->debug_abbrev_
= new Output_reduced_debug_abbrev_section(
1338 if (this->debug_info_
)
1339 this->debug_info_
->set_abbreviations(this->debug_abbrev_
);
1341 else if ((flags
& elfcpp::SHF_ALLOC
) == 0
1342 && parameters
->options().strip_debug_non_line()
1343 && strcmp(".debug_info", name
) == 0)
1345 os
= this->debug_info_
= new Output_reduced_debug_info_section(
1347 if (this->debug_abbrev_
)
1348 this->debug_info_
->set_abbreviations(this->debug_abbrev_
);
1352 // Sometimes .init_array*, .preinit_array* and .fini_array* do
1353 // not have correct section types. Force them here.
1354 if (type
== elfcpp::SHT_PROGBITS
)
1356 if (is_prefix_of(".init_array", name
))
1357 type
= elfcpp::SHT_INIT_ARRAY
;
1358 else if (is_prefix_of(".preinit_array", name
))
1359 type
= elfcpp::SHT_PREINIT_ARRAY
;
1360 else if (is_prefix_of(".fini_array", name
))
1361 type
= elfcpp::SHT_FINI_ARRAY
;
1364 // FIXME: const_cast is ugly.
1365 Target
* target
= const_cast<Target
*>(¶meters
->target());
1366 os
= target
->make_output_section(name
, type
, flags
);
1369 // With -z relro, we have to recognize the special sections by name.
1370 // There is no other way.
1371 bool is_relro_local
= false;
1372 if (!this->script_options_
->saw_sections_clause()
1373 && parameters
->options().relro()
1374 && type
== elfcpp::SHT_PROGBITS
1375 && (flags
& elfcpp::SHF_ALLOC
) != 0
1376 && (flags
& elfcpp::SHF_WRITE
) != 0)
1378 if (strcmp(name
, ".data.rel.ro") == 0)
1380 else if (strcmp(name
, ".data.rel.ro.local") == 0)
1383 is_relro_local
= true;
1385 else if (type
== elfcpp::SHT_INIT_ARRAY
1386 || type
== elfcpp::SHT_FINI_ARRAY
1387 || type
== elfcpp::SHT_PREINIT_ARRAY
)
1389 else if (strcmp(name
, ".ctors") == 0
1390 || strcmp(name
, ".dtors") == 0
1391 || strcmp(name
, ".jcr") == 0)
1398 if (order
== ORDER_INVALID
&& (flags
& elfcpp::SHF_ALLOC
) != 0)
1399 order
= this->default_section_order(os
, is_relro_local
);
1401 os
->set_order(order
);
1403 parameters
->target().new_output_section(os
);
1405 this->section_list_
.push_back(os
);
1407 // The GNU linker by default sorts some sections by priority, so we
1408 // do the same. We need to know that this might happen before we
1409 // attach any input sections.
1410 if (!this->script_options_
->saw_sections_clause()
1411 && !parameters
->options().relocatable()
1412 && (strcmp(name
, ".init_array") == 0
1413 || strcmp(name
, ".fini_array") == 0
1414 || (!parameters
->options().ctors_in_init_array()
1415 && (strcmp(name
, ".ctors") == 0
1416 || strcmp(name
, ".dtors") == 0))))
1417 os
->set_may_sort_attached_input_sections();
1419 // Check for .stab*str sections, as .stab* sections need to link to
1421 if (type
== elfcpp::SHT_STRTAB
1422 && !this->have_stabstr_section_
1423 && strncmp(name
, ".stab", 5) == 0
1424 && strcmp(name
+ strlen(name
) - 3, "str") == 0)
1425 this->have_stabstr_section_
= true;
1427 // During a full incremental link, we add patch space to most
1428 // PROGBITS and NOBITS sections. Flag those that may be
1429 // arbitrarily padded.
1430 if ((type
== elfcpp::SHT_PROGBITS
|| type
== elfcpp::SHT_NOBITS
)
1431 && order
!= ORDER_INTERP
1432 && order
!= ORDER_INIT
1433 && order
!= ORDER_PLT
1434 && order
!= ORDER_FINI
1435 && order
!= ORDER_RELRO_LAST
1436 && order
!= ORDER_NON_RELRO_FIRST
1437 && strcmp(name
, ".ctors") != 0
1438 && strcmp(name
, ".dtors") != 0
1439 && strcmp(name
, ".jcr") != 0)
1440 os
->set_is_patch_space_allowed();
1442 // If we have already attached the sections to segments, then we
1443 // need to attach this one now. This happens for sections created
1444 // directly by the linker.
1445 if (this->sections_are_attached_
)
1446 this->attach_section_to_segment(os
);
1451 // Return the default order in which a section should be placed in an
1452 // output segment. This function captures a lot of the ideas in
1453 // ld/scripttempl/elf.sc in the GNU linker. Note that the order of a
1454 // linker created section is normally set when the section is created;
1455 // this function is used for input sections.
1457 Output_section_order
1458 Layout::default_section_order(Output_section
* os
, bool is_relro_local
)
1460 gold_assert((os
->flags() & elfcpp::SHF_ALLOC
) != 0);
1461 bool is_write
= (os
->flags() & elfcpp::SHF_WRITE
) != 0;
1462 bool is_execinstr
= (os
->flags() & elfcpp::SHF_EXECINSTR
) != 0;
1463 bool is_bss
= false;
1468 case elfcpp::SHT_PROGBITS
:
1470 case elfcpp::SHT_NOBITS
:
1473 case elfcpp::SHT_RELA
:
1474 case elfcpp::SHT_REL
:
1476 return ORDER_DYNAMIC_RELOCS
;
1478 case elfcpp::SHT_HASH
:
1479 case elfcpp::SHT_DYNAMIC
:
1480 case elfcpp::SHT_SHLIB
:
1481 case elfcpp::SHT_DYNSYM
:
1482 case elfcpp::SHT_GNU_HASH
:
1483 case elfcpp::SHT_GNU_verdef
:
1484 case elfcpp::SHT_GNU_verneed
:
1485 case elfcpp::SHT_GNU_versym
:
1487 return ORDER_DYNAMIC_LINKER
;
1489 case elfcpp::SHT_NOTE
:
1490 return is_write
? ORDER_RW_NOTE
: ORDER_RO_NOTE
;
1493 if ((os
->flags() & elfcpp::SHF_TLS
) != 0)
1494 return is_bss
? ORDER_TLS_BSS
: ORDER_TLS_DATA
;
1496 if (!is_bss
&& !is_write
)
1500 if (strcmp(os
->name(), ".init") == 0)
1502 else if (strcmp(os
->name(), ".fini") == 0)
1505 return is_execinstr
? ORDER_TEXT
: ORDER_READONLY
;
1509 return is_relro_local
? ORDER_RELRO_LOCAL
: ORDER_RELRO
;
1511 if (os
->is_small_section())
1512 return is_bss
? ORDER_SMALL_BSS
: ORDER_SMALL_DATA
;
1513 if (os
->is_large_section())
1514 return is_bss
? ORDER_LARGE_BSS
: ORDER_LARGE_DATA
;
1516 return is_bss
? ORDER_BSS
: ORDER_DATA
;
1519 // Attach output sections to segments. This is called after we have
1520 // seen all the input sections.
1523 Layout::attach_sections_to_segments()
1525 for (Section_list::iterator p
= this->section_list_
.begin();
1526 p
!= this->section_list_
.end();
1528 this->attach_section_to_segment(*p
);
1530 this->sections_are_attached_
= true;
1533 // Attach an output section to a segment.
1536 Layout::attach_section_to_segment(Output_section
* os
)
1538 if ((os
->flags() & elfcpp::SHF_ALLOC
) == 0)
1539 this->unattached_section_list_
.push_back(os
);
1541 this->attach_allocated_section_to_segment(os
);
1544 // Attach an allocated output section to a segment.
1547 Layout::attach_allocated_section_to_segment(Output_section
* os
)
1549 elfcpp::Elf_Xword flags
= os
->flags();
1550 gold_assert((flags
& elfcpp::SHF_ALLOC
) != 0);
1552 if (parameters
->options().relocatable())
1555 // If we have a SECTIONS clause, we can't handle the attachment to
1556 // segments until after we've seen all the sections.
1557 if (this->script_options_
->saw_sections_clause())
1560 gold_assert(!this->script_options_
->saw_phdrs_clause());
1562 // This output section goes into a PT_LOAD segment.
1564 elfcpp::Elf_Word seg_flags
= Layout::section_flags_to_segment(flags
);
1566 // Check for --section-start.
1568 bool is_address_set
= parameters
->options().section_start(os
->name(), &addr
);
1570 // In general the only thing we really care about for PT_LOAD
1571 // segments is whether or not they are writable or executable,
1572 // so that is how we search for them.
1573 // Large data sections also go into their own PT_LOAD segment.
1574 // People who need segments sorted on some other basis will
1575 // have to use a linker script.
1577 Segment_list::const_iterator p
;
1578 for (p
= this->segment_list_
.begin();
1579 p
!= this->segment_list_
.end();
1582 if ((*p
)->type() != elfcpp::PT_LOAD
)
1584 if (!parameters
->options().omagic()
1585 && ((*p
)->flags() & elfcpp::PF_W
) != (seg_flags
& elfcpp::PF_W
))
1587 if (parameters
->options().rosegment()
1588 && ((*p
)->flags() & elfcpp::PF_X
) != (seg_flags
& elfcpp::PF_X
))
1590 // If -Tbss was specified, we need to separate the data and BSS
1592 if (parameters
->options().user_set_Tbss())
1594 if ((os
->type() == elfcpp::SHT_NOBITS
)
1595 == (*p
)->has_any_data_sections())
1598 if (os
->is_large_data_section() && !(*p
)->is_large_data_segment())
1603 if ((*p
)->are_addresses_set())
1606 (*p
)->add_initial_output_data(os
);
1607 (*p
)->update_flags_for_output_section(seg_flags
);
1608 (*p
)->set_addresses(addr
, addr
);
1612 (*p
)->add_output_section_to_load(this, os
, seg_flags
);
1616 if (p
== this->segment_list_
.end())
1618 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_LOAD
,
1620 if (os
->is_large_data_section())
1621 oseg
->set_is_large_data_segment();
1622 oseg
->add_output_section_to_load(this, os
, seg_flags
);
1624 oseg
->set_addresses(addr
, addr
);
1627 // If we see a loadable SHT_NOTE section, we create a PT_NOTE
1629 if (os
->type() == elfcpp::SHT_NOTE
)
1631 // See if we already have an equivalent PT_NOTE segment.
1632 for (p
= this->segment_list_
.begin();
1633 p
!= segment_list_
.end();
1636 if ((*p
)->type() == elfcpp::PT_NOTE
1637 && (((*p
)->flags() & elfcpp::PF_W
)
1638 == (seg_flags
& elfcpp::PF_W
)))
1640 (*p
)->add_output_section_to_nonload(os
, seg_flags
);
1645 if (p
== this->segment_list_
.end())
1647 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_NOTE
,
1649 oseg
->add_output_section_to_nonload(os
, seg_flags
);
1653 // If we see a loadable SHF_TLS section, we create a PT_TLS
1654 // segment. There can only be one such segment.
1655 if ((flags
& elfcpp::SHF_TLS
) != 0)
1657 if (this->tls_segment_
== NULL
)
1658 this->make_output_segment(elfcpp::PT_TLS
, seg_flags
);
1659 this->tls_segment_
->add_output_section_to_nonload(os
, seg_flags
);
1662 // If -z relro is in effect, and we see a relro section, we create a
1663 // PT_GNU_RELRO segment. There can only be one such segment.
1664 if (os
->is_relro() && parameters
->options().relro())
1666 gold_assert(seg_flags
== (elfcpp::PF_R
| elfcpp::PF_W
));
1667 if (this->relro_segment_
== NULL
)
1668 this->make_output_segment(elfcpp::PT_GNU_RELRO
, seg_flags
);
1669 this->relro_segment_
->add_output_section_to_nonload(os
, seg_flags
);
1672 // If we see a section named .interp, put it into a PT_INTERP
1673 // segment. This seems broken to me, but this is what GNU ld does,
1674 // and glibc expects it.
1675 if (strcmp(os
->name(), ".interp") == 0
1676 && !this->script_options_
->saw_phdrs_clause())
1678 if (this->interp_segment_
== NULL
)
1679 this->make_output_segment(elfcpp::PT_INTERP
, seg_flags
);
1681 gold_warning(_("multiple '.interp' sections in input files "
1682 "may cause confusing PT_INTERP segment"));
1683 this->interp_segment_
->add_output_section_to_nonload(os
, seg_flags
);
1687 // Make an output section for a script.
1690 Layout::make_output_section_for_script(
1692 Script_sections::Section_type section_type
)
1694 name
= this->namepool_
.add(name
, false, NULL
);
1695 elfcpp::Elf_Xword sh_flags
= elfcpp::SHF_ALLOC
;
1696 if (section_type
== Script_sections::ST_NOLOAD
)
1698 Output_section
* os
= this->make_output_section(name
, elfcpp::SHT_PROGBITS
,
1699 sh_flags
, ORDER_INVALID
,
1701 os
->set_found_in_sections_clause();
1702 if (section_type
== Script_sections::ST_NOLOAD
)
1703 os
->set_is_noload();
1707 // Return the number of segments we expect to see.
1710 Layout::expected_segment_count() const
1712 size_t ret
= this->segment_list_
.size();
1714 // If we didn't see a SECTIONS clause in a linker script, we should
1715 // already have the complete list of segments. Otherwise we ask the
1716 // SECTIONS clause how many segments it expects, and add in the ones
1717 // we already have (PT_GNU_STACK, PT_GNU_EH_FRAME, etc.)
1719 if (!this->script_options_
->saw_sections_clause())
1723 const Script_sections
* ss
= this->script_options_
->script_sections();
1724 return ret
+ ss
->expected_segment_count(this);
1728 // Handle the .note.GNU-stack section at layout time. SEEN_GNU_STACK
1729 // is whether we saw a .note.GNU-stack section in the object file.
1730 // GNU_STACK_FLAGS is the section flags. The flags give the
1731 // protection required for stack memory. We record this in an
1732 // executable as a PT_GNU_STACK segment. If an object file does not
1733 // have a .note.GNU-stack segment, we must assume that it is an old
1734 // object. On some targets that will force an executable stack.
1737 Layout::layout_gnu_stack(bool seen_gnu_stack
, uint64_t gnu_stack_flags
,
1740 if (!seen_gnu_stack
)
1742 this->input_without_gnu_stack_note_
= true;
1743 if (parameters
->options().warn_execstack()
1744 && parameters
->target().is_default_stack_executable())
1745 gold_warning(_("%s: missing .note.GNU-stack section"
1746 " implies executable stack"),
1747 obj
->name().c_str());
1751 this->input_with_gnu_stack_note_
= true;
1752 if ((gnu_stack_flags
& elfcpp::SHF_EXECINSTR
) != 0)
1754 this->input_requires_executable_stack_
= true;
1755 if (parameters
->options().warn_execstack()
1756 || parameters
->options().is_stack_executable())
1757 gold_warning(_("%s: requires executable stack"),
1758 obj
->name().c_str());
1763 // Create automatic note sections.
1766 Layout::create_notes()
1768 this->create_gold_note();
1769 this->create_executable_stack_info();
1770 this->create_build_id();
1773 // Create the dynamic sections which are needed before we read the
1777 Layout::create_initial_dynamic_sections(Symbol_table
* symtab
)
1779 if (parameters
->doing_static_link())
1782 this->dynamic_section_
= this->choose_output_section(NULL
, ".dynamic",
1783 elfcpp::SHT_DYNAMIC
,
1785 | elfcpp::SHF_WRITE
),
1789 // A linker script may discard .dynamic, so check for NULL.
1790 if (this->dynamic_section_
!= NULL
)
1792 this->dynamic_symbol_
=
1793 symtab
->define_in_output_data("_DYNAMIC", NULL
,
1794 Symbol_table::PREDEFINED
,
1795 this->dynamic_section_
, 0, 0,
1796 elfcpp::STT_OBJECT
, elfcpp::STB_LOCAL
,
1797 elfcpp::STV_HIDDEN
, 0, false, false);
1799 this->dynamic_data_
= new Output_data_dynamic(&this->dynpool_
);
1801 this->dynamic_section_
->add_output_section_data(this->dynamic_data_
);
1805 // For each output section whose name can be represented as C symbol,
1806 // define __start and __stop symbols for the section. This is a GNU
1810 Layout::define_section_symbols(Symbol_table
* symtab
)
1812 for (Section_list::const_iterator p
= this->section_list_
.begin();
1813 p
!= this->section_list_
.end();
1816 const char* const name
= (*p
)->name();
1817 if (is_cident(name
))
1819 const std::string
name_string(name
);
1820 const std::string
start_name(cident_section_start_prefix
1822 const std::string
stop_name(cident_section_stop_prefix
1825 symtab
->define_in_output_data(start_name
.c_str(),
1827 Symbol_table::PREDEFINED
,
1833 elfcpp::STV_DEFAULT
,
1835 false, // offset_is_from_end
1836 true); // only_if_ref
1838 symtab
->define_in_output_data(stop_name
.c_str(),
1840 Symbol_table::PREDEFINED
,
1846 elfcpp::STV_DEFAULT
,
1848 true, // offset_is_from_end
1849 true); // only_if_ref
1854 // Define symbols for group signatures.
1857 Layout::define_group_signatures(Symbol_table
* symtab
)
1859 for (Group_signatures::iterator p
= this->group_signatures_
.begin();
1860 p
!= this->group_signatures_
.end();
1863 Symbol
* sym
= symtab
->lookup(p
->signature
, NULL
);
1865 p
->section
->set_info_symndx(sym
);
1868 // Force the name of the group section to the group
1869 // signature, and use the group's section symbol as the
1870 // signature symbol.
1871 if (strcmp(p
->section
->name(), p
->signature
) != 0)
1873 const char* name
= this->namepool_
.add(p
->signature
,
1875 p
->section
->set_name(name
);
1877 p
->section
->set_needs_symtab_index();
1878 p
->section
->set_info_section_symndx(p
->section
);
1882 this->group_signatures_
.clear();
1885 // Find the first read-only PT_LOAD segment, creating one if
1889 Layout::find_first_load_seg()
1891 Output_segment
* best
= NULL
;
1892 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
1893 p
!= this->segment_list_
.end();
1896 if ((*p
)->type() == elfcpp::PT_LOAD
1897 && ((*p
)->flags() & elfcpp::PF_R
) != 0
1898 && (parameters
->options().omagic()
1899 || ((*p
)->flags() & elfcpp::PF_W
) == 0))
1901 if (best
== NULL
|| this->segment_precedes(*p
, best
))
1908 gold_assert(!this->script_options_
->saw_phdrs_clause());
1910 Output_segment
* load_seg
= this->make_output_segment(elfcpp::PT_LOAD
,
1915 // Save states of all current output segments. Store saved states
1916 // in SEGMENT_STATES.
1919 Layout::save_segments(Segment_states
* segment_states
)
1921 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
1922 p
!= this->segment_list_
.end();
1925 Output_segment
* segment
= *p
;
1927 Output_segment
* copy
= new Output_segment(*segment
);
1928 (*segment_states
)[segment
] = copy
;
1932 // Restore states of output segments and delete any segment not found in
1936 Layout::restore_segments(const Segment_states
* segment_states
)
1938 // Go through the segment list and remove any segment added in the
1940 this->tls_segment_
= NULL
;
1941 this->relro_segment_
= NULL
;
1942 Segment_list::iterator list_iter
= this->segment_list_
.begin();
1943 while (list_iter
!= this->segment_list_
.end())
1945 Output_segment
* segment
= *list_iter
;
1946 Segment_states::const_iterator states_iter
=
1947 segment_states
->find(segment
);
1948 if (states_iter
!= segment_states
->end())
1950 const Output_segment
* copy
= states_iter
->second
;
1951 // Shallow copy to restore states.
1954 // Also fix up TLS and RELRO segment pointers as appropriate.
1955 if (segment
->type() == elfcpp::PT_TLS
)
1956 this->tls_segment_
= segment
;
1957 else if (segment
->type() == elfcpp::PT_GNU_RELRO
)
1958 this->relro_segment_
= segment
;
1964 list_iter
= this->segment_list_
.erase(list_iter
);
1965 // This is a segment created during section layout. It should be
1966 // safe to remove it since we should have removed all pointers to it.
1972 // Clean up after relaxation so that sections can be laid out again.
1975 Layout::clean_up_after_relaxation()
1977 // Restore the segments to point state just prior to the relaxation loop.
1978 Script_sections
* script_section
= this->script_options_
->script_sections();
1979 script_section
->release_segments();
1980 this->restore_segments(this->segment_states_
);
1982 // Reset section addresses and file offsets
1983 for (Section_list::iterator p
= this->section_list_
.begin();
1984 p
!= this->section_list_
.end();
1987 (*p
)->restore_states();
1989 // If an input section changes size because of relaxation,
1990 // we need to adjust the section offsets of all input sections.
1991 // after such a section.
1992 if ((*p
)->section_offsets_need_adjustment())
1993 (*p
)->adjust_section_offsets();
1995 (*p
)->reset_address_and_file_offset();
1998 // Reset special output object address and file offsets.
1999 for (Data_list::iterator p
= this->special_output_list_
.begin();
2000 p
!= this->special_output_list_
.end();
2002 (*p
)->reset_address_and_file_offset();
2004 // A linker script may have created some output section data objects.
2005 // They are useless now.
2006 for (Output_section_data_list::const_iterator p
=
2007 this->script_output_section_data_list_
.begin();
2008 p
!= this->script_output_section_data_list_
.end();
2011 this->script_output_section_data_list_
.clear();
2014 // Prepare for relaxation.
2017 Layout::prepare_for_relaxation()
2019 // Create an relaxation debug check if in debugging mode.
2020 if (is_debugging_enabled(DEBUG_RELAXATION
))
2021 this->relaxation_debug_check_
= new Relaxation_debug_check();
2023 // Save segment states.
2024 this->segment_states_
= new Segment_states();
2025 this->save_segments(this->segment_states_
);
2027 for(Section_list::const_iterator p
= this->section_list_
.begin();
2028 p
!= this->section_list_
.end();
2030 (*p
)->save_states();
2032 if (is_debugging_enabled(DEBUG_RELAXATION
))
2033 this->relaxation_debug_check_
->check_output_data_for_reset_values(
2034 this->section_list_
, this->special_output_list_
);
2036 // Also enable recording of output section data from scripts.
2037 this->record_output_section_data_from_script_
= true;
2040 // Relaxation loop body: If target has no relaxation, this runs only once
2041 // Otherwise, the target relaxation hook is called at the end of
2042 // each iteration. If the hook returns true, it means re-layout of
2043 // section is required.
2045 // The number of segments created by a linking script without a PHDRS
2046 // clause may be affected by section sizes and alignments. There is
2047 // a remote chance that relaxation causes different number of PT_LOAD
2048 // segments are created and sections are attached to different segments.
2049 // Therefore, we always throw away all segments created during section
2050 // layout. In order to be able to restart the section layout, we keep
2051 // a copy of the segment list right before the relaxation loop and use
2052 // that to restore the segments.
2054 // PASS is the current relaxation pass number.
2055 // SYMTAB is a symbol table.
2056 // PLOAD_SEG is the address of a pointer for the load segment.
2057 // PHDR_SEG is a pointer to the PHDR segment.
2058 // SEGMENT_HEADERS points to the output segment header.
2059 // FILE_HEADER points to the output file header.
2060 // PSHNDX is the address to store the output section index.
2063 Layout::relaxation_loop_body(
2066 Symbol_table
* symtab
,
2067 Output_segment
** pload_seg
,
2068 Output_segment
* phdr_seg
,
2069 Output_segment_headers
* segment_headers
,
2070 Output_file_header
* file_header
,
2071 unsigned int* pshndx
)
2073 // If this is not the first iteration, we need to clean up after
2074 // relaxation so that we can lay out the sections again.
2076 this->clean_up_after_relaxation();
2078 // If there is a SECTIONS clause, put all the input sections into
2079 // the required order.
2080 Output_segment
* load_seg
;
2081 if (this->script_options_
->saw_sections_clause())
2082 load_seg
= this->set_section_addresses_from_script(symtab
);
2083 else if (parameters
->options().relocatable())
2086 load_seg
= this->find_first_load_seg();
2088 if (parameters
->options().oformat_enum()
2089 != General_options::OBJECT_FORMAT_ELF
)
2092 // If the user set the address of the text segment, that may not be
2093 // compatible with putting the segment headers and file headers into
2095 if (parameters
->options().user_set_Ttext())
2098 gold_assert(phdr_seg
== NULL
2100 || this->script_options_
->saw_sections_clause());
2102 // If the address of the load segment we found has been set by
2103 // --section-start rather than by a script, then adjust the VMA and
2104 // LMA downward if possible to include the file and section headers.
2105 uint64_t header_gap
= 0;
2106 if (load_seg
!= NULL
2107 && load_seg
->are_addresses_set()
2108 && !this->script_options_
->saw_sections_clause()
2109 && !parameters
->options().relocatable())
2111 file_header
->finalize_data_size();
2112 segment_headers
->finalize_data_size();
2113 size_t sizeof_headers
= (file_header
->data_size()
2114 + segment_headers
->data_size());
2115 const uint64_t abi_pagesize
= target
->abi_pagesize();
2116 uint64_t hdr_paddr
= load_seg
->paddr() - sizeof_headers
;
2117 hdr_paddr
&= ~(abi_pagesize
- 1);
2118 uint64_t subtract
= load_seg
->paddr() - hdr_paddr
;
2119 if (load_seg
->paddr() < subtract
|| load_seg
->vaddr() < subtract
)
2123 load_seg
->set_addresses(load_seg
->vaddr() - subtract
,
2124 load_seg
->paddr() - subtract
);
2125 header_gap
= subtract
- sizeof_headers
;
2129 // Lay out the segment headers.
2130 if (!parameters
->options().relocatable())
2132 gold_assert(segment_headers
!= NULL
);
2133 if (header_gap
!= 0 && load_seg
!= NULL
)
2135 Output_data_zero_fill
* z
= new Output_data_zero_fill(header_gap
, 1);
2136 load_seg
->add_initial_output_data(z
);
2138 if (load_seg
!= NULL
)
2139 load_seg
->add_initial_output_data(segment_headers
);
2140 if (phdr_seg
!= NULL
)
2141 phdr_seg
->add_initial_output_data(segment_headers
);
2144 // Lay out the file header.
2145 if (load_seg
!= NULL
)
2146 load_seg
->add_initial_output_data(file_header
);
2148 if (this->script_options_
->saw_phdrs_clause()
2149 && !parameters
->options().relocatable())
2151 // Support use of FILEHDRS and PHDRS attachments in a PHDRS
2152 // clause in a linker script.
2153 Script_sections
* ss
= this->script_options_
->script_sections();
2154 ss
->put_headers_in_phdrs(file_header
, segment_headers
);
2157 // We set the output section indexes in set_segment_offsets and
2158 // set_section_indexes.
2161 // Set the file offsets of all the segments, and all the sections
2164 if (!parameters
->options().relocatable())
2165 off
= this->set_segment_offsets(target
, load_seg
, pshndx
);
2167 off
= this->set_relocatable_section_offsets(file_header
, pshndx
);
2169 // Verify that the dummy relaxation does not change anything.
2170 if (is_debugging_enabled(DEBUG_RELAXATION
))
2173 this->relaxation_debug_check_
->read_sections(this->section_list_
);
2175 this->relaxation_debug_check_
->verify_sections(this->section_list_
);
2178 *pload_seg
= load_seg
;
2182 // Search the list of patterns and find the postion of the given section
2183 // name in the output section. If the section name matches a glob
2184 // pattern and a non-glob name, then the non-glob position takes
2185 // precedence. Return 0 if no match is found.
2188 Layout::find_section_order_index(const std::string
& section_name
)
2190 Unordered_map
<std::string
, unsigned int>::iterator map_it
;
2191 map_it
= this->input_section_position_
.find(section_name
);
2192 if (map_it
!= this->input_section_position_
.end())
2193 return map_it
->second
;
2195 // Absolute match failed. Linear search the glob patterns.
2196 std::vector
<std::string
>::iterator it
;
2197 for (it
= this->input_section_glob_
.begin();
2198 it
!= this->input_section_glob_
.end();
2201 if (fnmatch((*it
).c_str(), section_name
.c_str(), FNM_NOESCAPE
) == 0)
2203 map_it
= this->input_section_position_
.find(*it
);
2204 gold_assert(map_it
!= this->input_section_position_
.end());
2205 return map_it
->second
;
2211 // Read the sequence of input sections from the file specified with
2212 // --section-ordering-file.
2215 Layout::read_layout_from_file()
2217 const char* filename
= parameters
->options().section_ordering_file();
2223 gold_fatal(_("unable to open --section-ordering-file file %s: %s"),
2224 filename
, strerror(errno
));
2226 std::getline(in
, line
); // this chops off the trailing \n, if any
2227 unsigned int position
= 1;
2231 if (!line
.empty() && line
[line
.length() - 1] == '\r') // Windows
2232 line
.resize(line
.length() - 1);
2233 // Ignore comments, beginning with '#'
2236 std::getline(in
, line
);
2239 this->input_section_position_
[line
] = position
;
2240 // Store all glob patterns in a vector.
2241 if (is_wildcard_string(line
.c_str()))
2242 this->input_section_glob_
.push_back(line
);
2244 std::getline(in
, line
);
2248 // Finalize the layout. When this is called, we have created all the
2249 // output sections and all the output segments which are based on
2250 // input sections. We have several things to do, and we have to do
2251 // them in the right order, so that we get the right results correctly
2254 // 1) Finalize the list of output segments and create the segment
2257 // 2) Finalize the dynamic symbol table and associated sections.
2259 // 3) Determine the final file offset of all the output segments.
2261 // 4) Determine the final file offset of all the SHF_ALLOC output
2264 // 5) Create the symbol table sections and the section name table
2267 // 6) Finalize the symbol table: set symbol values to their final
2268 // value and make a final determination of which symbols are going
2269 // into the output symbol table.
2271 // 7) Create the section table header.
2273 // 8) Determine the final file offset of all the output sections which
2274 // are not SHF_ALLOC, including the section table header.
2276 // 9) Finalize the ELF file header.
2278 // This function returns the size of the output file.
2281 Layout::finalize(const Input_objects
* input_objects
, Symbol_table
* symtab
,
2282 Target
* target
, const Task
* task
)
2284 target
->finalize_sections(this, input_objects
, symtab
);
2286 this->count_local_symbols(task
, input_objects
);
2288 this->link_stabs_sections();
2290 Output_segment
* phdr_seg
= NULL
;
2291 if (!parameters
->options().relocatable() && !parameters
->doing_static_link())
2293 // There was a dynamic object in the link. We need to create
2294 // some information for the dynamic linker.
2296 // Create the PT_PHDR segment which will hold the program
2298 if (!this->script_options_
->saw_phdrs_clause())
2299 phdr_seg
= this->make_output_segment(elfcpp::PT_PHDR
, elfcpp::PF_R
);
2301 // Create the dynamic symbol table, including the hash table.
2302 Output_section
* dynstr
;
2303 std::vector
<Symbol
*> dynamic_symbols
;
2304 unsigned int local_dynamic_count
;
2305 Versions
versions(*this->script_options()->version_script_info(),
2307 this->create_dynamic_symtab(input_objects
, symtab
, &dynstr
,
2308 &local_dynamic_count
, &dynamic_symbols
,
2311 // Create the .interp section to hold the name of the
2312 // interpreter, and put it in a PT_INTERP segment. Don't do it
2313 // if we saw a .interp section in an input file.
2314 if ((!parameters
->options().shared()
2315 || parameters
->options().dynamic_linker() != NULL
)
2316 && this->interp_segment_
== NULL
)
2317 this->create_interp(target
);
2319 // Finish the .dynamic section to hold the dynamic data, and put
2320 // it in a PT_DYNAMIC segment.
2321 this->finish_dynamic_section(input_objects
, symtab
);
2323 // We should have added everything we need to the dynamic string
2325 this->dynpool_
.set_string_offsets();
2327 // Create the version sections. We can't do this until the
2328 // dynamic string table is complete.
2329 this->create_version_sections(&versions
, symtab
, local_dynamic_count
,
2330 dynamic_symbols
, dynstr
);
2332 // Set the size of the _DYNAMIC symbol. We can't do this until
2333 // after we call create_version_sections.
2334 this->set_dynamic_symbol_size(symtab
);
2337 // Create segment headers.
2338 Output_segment_headers
* segment_headers
=
2339 (parameters
->options().relocatable()
2341 : new Output_segment_headers(this->segment_list_
));
2343 // Lay out the file header.
2344 Output_file_header
* file_header
= new Output_file_header(target
, symtab
,
2347 this->special_output_list_
.push_back(file_header
);
2348 if (segment_headers
!= NULL
)
2349 this->special_output_list_
.push_back(segment_headers
);
2351 // Find approriate places for orphan output sections if we are using
2353 if (this->script_options_
->saw_sections_clause())
2354 this->place_orphan_sections_in_script();
2356 Output_segment
* load_seg
;
2361 // Take a snapshot of the section layout as needed.
2362 if (target
->may_relax())
2363 this->prepare_for_relaxation();
2365 // Run the relaxation loop to lay out sections.
2368 off
= this->relaxation_loop_body(pass
, target
, symtab
, &load_seg
,
2369 phdr_seg
, segment_headers
, file_header
,
2373 while (target
->may_relax()
2374 && target
->relax(pass
, input_objects
, symtab
, this, task
));
2376 // Set the file offsets of all the non-data sections we've seen so
2377 // far which don't have to wait for the input sections. We need
2378 // this in order to finalize local symbols in non-allocated
2380 off
= this->set_section_offsets(off
, BEFORE_INPUT_SECTIONS_PASS
);
2382 // Set the section indexes of all unallocated sections seen so far,
2383 // in case any of them are somehow referenced by a symbol.
2384 shndx
= this->set_section_indexes(shndx
);
2386 // Create the symbol table sections.
2387 this->create_symtab_sections(input_objects
, symtab
, shndx
, &off
);
2388 if (!parameters
->doing_static_link())
2389 this->assign_local_dynsym_offsets(input_objects
);
2391 // Process any symbol assignments from a linker script. This must
2392 // be called after the symbol table has been finalized.
2393 this->script_options_
->finalize_symbols(symtab
, this);
2395 // Create the incremental inputs sections.
2396 if (this->incremental_inputs_
)
2398 this->incremental_inputs_
->finalize();
2399 this->create_incremental_info_sections(symtab
);
2402 // Create the .shstrtab section.
2403 Output_section
* shstrtab_section
= this->create_shstrtab();
2405 // Set the file offsets of the rest of the non-data sections which
2406 // don't have to wait for the input sections.
2407 off
= this->set_section_offsets(off
, BEFORE_INPUT_SECTIONS_PASS
);
2409 // Now that all sections have been created, set the section indexes
2410 // for any sections which haven't been done yet.
2411 shndx
= this->set_section_indexes(shndx
);
2413 // Create the section table header.
2414 this->create_shdrs(shstrtab_section
, &off
);
2416 // If there are no sections which require postprocessing, we can
2417 // handle the section names now, and avoid a resize later.
2418 if (!this->any_postprocessing_sections_
)
2420 off
= this->set_section_offsets(off
,
2421 POSTPROCESSING_SECTIONS_PASS
);
2423 this->set_section_offsets(off
,
2424 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
);
2427 file_header
->set_section_info(this->section_headers_
, shstrtab_section
);
2429 // Now we know exactly where everything goes in the output file
2430 // (except for non-allocated sections which require postprocessing).
2431 Output_data::layout_complete();
2433 this->output_file_size_
= off
;
2438 // Create a note header following the format defined in the ELF ABI.
2439 // NAME is the name, NOTE_TYPE is the type, SECTION_NAME is the name
2440 // of the section to create, DESCSZ is the size of the descriptor.
2441 // ALLOCATE is true if the section should be allocated in memory.
2442 // This returns the new note section. It sets *TRAILING_PADDING to
2443 // the number of trailing zero bytes required.
2446 Layout::create_note(const char* name
, int note_type
,
2447 const char* section_name
, size_t descsz
,
2448 bool allocate
, size_t* trailing_padding
)
2450 // Authorities all agree that the values in a .note field should
2451 // be aligned on 4-byte boundaries for 32-bit binaries. However,
2452 // they differ on what the alignment is for 64-bit binaries.
2453 // The GABI says unambiguously they take 8-byte alignment:
2454 // http://sco.com/developers/gabi/latest/ch5.pheader.html#note_section
2455 // Other documentation says alignment should always be 4 bytes:
2456 // http://www.netbsd.org/docs/kernel/elf-notes.html#note-format
2457 // GNU ld and GNU readelf both support the latter (at least as of
2458 // version 2.16.91), and glibc always generates the latter for
2459 // .note.ABI-tag (as of version 1.6), so that's the one we go with
2461 #ifdef GABI_FORMAT_FOR_DOTNOTE_SECTION // This is not defined by default.
2462 const int size
= parameters
->target().get_size();
2464 const int size
= 32;
2467 // The contents of the .note section.
2468 size_t namesz
= strlen(name
) + 1;
2469 size_t aligned_namesz
= align_address(namesz
, size
/ 8);
2470 size_t aligned_descsz
= align_address(descsz
, size
/ 8);
2472 size_t notehdrsz
= 3 * (size
/ 8) + aligned_namesz
;
2474 unsigned char* buffer
= new unsigned char[notehdrsz
];
2475 memset(buffer
, 0, notehdrsz
);
2477 bool is_big_endian
= parameters
->target().is_big_endian();
2483 elfcpp::Swap
<32, false>::writeval(buffer
, namesz
);
2484 elfcpp::Swap
<32, false>::writeval(buffer
+ 4, descsz
);
2485 elfcpp::Swap
<32, false>::writeval(buffer
+ 8, note_type
);
2489 elfcpp::Swap
<32, true>::writeval(buffer
, namesz
);
2490 elfcpp::Swap
<32, true>::writeval(buffer
+ 4, descsz
);
2491 elfcpp::Swap
<32, true>::writeval(buffer
+ 8, note_type
);
2494 else if (size
== 64)
2498 elfcpp::Swap
<64, false>::writeval(buffer
, namesz
);
2499 elfcpp::Swap
<64, false>::writeval(buffer
+ 8, descsz
);
2500 elfcpp::Swap
<64, false>::writeval(buffer
+ 16, note_type
);
2504 elfcpp::Swap
<64, true>::writeval(buffer
, namesz
);
2505 elfcpp::Swap
<64, true>::writeval(buffer
+ 8, descsz
);
2506 elfcpp::Swap
<64, true>::writeval(buffer
+ 16, note_type
);
2512 memcpy(buffer
+ 3 * (size
/ 8), name
, namesz
);
2514 elfcpp::Elf_Xword flags
= 0;
2515 Output_section_order order
= ORDER_INVALID
;
2518 flags
= elfcpp::SHF_ALLOC
;
2519 order
= ORDER_RO_NOTE
;
2521 Output_section
* os
= this->choose_output_section(NULL
, section_name
,
2523 flags
, false, order
, false);
2527 Output_section_data
* posd
= new Output_data_const_buffer(buffer
, notehdrsz
,
2530 os
->add_output_section_data(posd
);
2532 *trailing_padding
= aligned_descsz
- descsz
;
2537 // For an executable or shared library, create a note to record the
2538 // version of gold used to create the binary.
2541 Layout::create_gold_note()
2543 if (parameters
->options().relocatable()
2544 || parameters
->incremental_update())
2547 std::string desc
= std::string("gold ") + gold::get_version_string();
2549 size_t trailing_padding
;
2550 Output_section
* os
= this->create_note("GNU", elfcpp::NT_GNU_GOLD_VERSION
,
2551 ".note.gnu.gold-version", desc
.size(),
2552 false, &trailing_padding
);
2556 Output_section_data
* posd
= new Output_data_const(desc
, 4);
2557 os
->add_output_section_data(posd
);
2559 if (trailing_padding
> 0)
2561 posd
= new Output_data_zero_fill(trailing_padding
, 0);
2562 os
->add_output_section_data(posd
);
2566 // Record whether the stack should be executable. This can be set
2567 // from the command line using the -z execstack or -z noexecstack
2568 // options. Otherwise, if any input file has a .note.GNU-stack
2569 // section with the SHF_EXECINSTR flag set, the stack should be
2570 // executable. Otherwise, if at least one input file a
2571 // .note.GNU-stack section, and some input file has no .note.GNU-stack
2572 // section, we use the target default for whether the stack should be
2573 // executable. Otherwise, we don't generate a stack note. When
2574 // generating a object file, we create a .note.GNU-stack section with
2575 // the appropriate marking. When generating an executable or shared
2576 // library, we create a PT_GNU_STACK segment.
2579 Layout::create_executable_stack_info()
2581 bool is_stack_executable
;
2582 if (parameters
->options().is_execstack_set())
2583 is_stack_executable
= parameters
->options().is_stack_executable();
2584 else if (!this->input_with_gnu_stack_note_
)
2588 if (this->input_requires_executable_stack_
)
2589 is_stack_executable
= true;
2590 else if (this->input_without_gnu_stack_note_
)
2591 is_stack_executable
=
2592 parameters
->target().is_default_stack_executable();
2594 is_stack_executable
= false;
2597 if (parameters
->options().relocatable())
2599 const char* name
= this->namepool_
.add(".note.GNU-stack", false, NULL
);
2600 elfcpp::Elf_Xword flags
= 0;
2601 if (is_stack_executable
)
2602 flags
|= elfcpp::SHF_EXECINSTR
;
2603 this->make_output_section(name
, elfcpp::SHT_PROGBITS
, flags
,
2604 ORDER_INVALID
, false);
2608 if (this->script_options_
->saw_phdrs_clause())
2610 int flags
= elfcpp::PF_R
| elfcpp::PF_W
;
2611 if (is_stack_executable
)
2612 flags
|= elfcpp::PF_X
;
2613 this->make_output_segment(elfcpp::PT_GNU_STACK
, flags
);
2617 // If --build-id was used, set up the build ID note.
2620 Layout::create_build_id()
2622 if (!parameters
->options().user_set_build_id())
2625 const char* style
= parameters
->options().build_id();
2626 if (strcmp(style
, "none") == 0)
2629 // Set DESCSZ to the size of the note descriptor. When possible,
2630 // set DESC to the note descriptor contents.
2633 if (strcmp(style
, "md5") == 0)
2635 else if (strcmp(style
, "sha1") == 0)
2637 else if (strcmp(style
, "uuid") == 0)
2639 const size_t uuidsz
= 128 / 8;
2641 char buffer
[uuidsz
];
2642 memset(buffer
, 0, uuidsz
);
2644 int descriptor
= open_descriptor(-1, "/dev/urandom", O_RDONLY
);
2646 gold_error(_("--build-id=uuid failed: could not open /dev/urandom: %s"),
2650 ssize_t got
= ::read(descriptor
, buffer
, uuidsz
);
2651 release_descriptor(descriptor
, true);
2653 gold_error(_("/dev/urandom: read failed: %s"), strerror(errno
));
2654 else if (static_cast<size_t>(got
) != uuidsz
)
2655 gold_error(_("/dev/urandom: expected %zu bytes, got %zd bytes"),
2659 desc
.assign(buffer
, uuidsz
);
2662 else if (strncmp(style
, "0x", 2) == 0)
2665 const char* p
= style
+ 2;
2668 if (hex_p(p
[0]) && hex_p(p
[1]))
2670 char c
= (hex_value(p
[0]) << 4) | hex_value(p
[1]);
2674 else if (*p
== '-' || *p
== ':')
2677 gold_fatal(_("--build-id argument '%s' not a valid hex number"),
2680 descsz
= desc
.size();
2683 gold_fatal(_("unrecognized --build-id argument '%s'"), style
);
2686 size_t trailing_padding
;
2687 Output_section
* os
= this->create_note("GNU", elfcpp::NT_GNU_BUILD_ID
,
2688 ".note.gnu.build-id", descsz
, true,
2695 // We know the value already, so we fill it in now.
2696 gold_assert(desc
.size() == descsz
);
2698 Output_section_data
* posd
= new Output_data_const(desc
, 4);
2699 os
->add_output_section_data(posd
);
2701 if (trailing_padding
!= 0)
2703 posd
= new Output_data_zero_fill(trailing_padding
, 0);
2704 os
->add_output_section_data(posd
);
2709 // We need to compute a checksum after we have completed the
2711 gold_assert(trailing_padding
== 0);
2712 this->build_id_note_
= new Output_data_zero_fill(descsz
, 4);
2713 os
->add_output_section_data(this->build_id_note_
);
2717 // If we have both .stabXX and .stabXXstr sections, then the sh_link
2718 // field of the former should point to the latter. I'm not sure who
2719 // started this, but the GNU linker does it, and some tools depend
2723 Layout::link_stabs_sections()
2725 if (!this->have_stabstr_section_
)
2728 for (Section_list::iterator p
= this->section_list_
.begin();
2729 p
!= this->section_list_
.end();
2732 if ((*p
)->type() != elfcpp::SHT_STRTAB
)
2735 const char* name
= (*p
)->name();
2736 if (strncmp(name
, ".stab", 5) != 0)
2739 size_t len
= strlen(name
);
2740 if (strcmp(name
+ len
- 3, "str") != 0)
2743 std::string
stab_name(name
, len
- 3);
2744 Output_section
* stab_sec
;
2745 stab_sec
= this->find_output_section(stab_name
.c_str());
2746 if (stab_sec
!= NULL
)
2747 stab_sec
->set_link_section(*p
);
2751 // Create .gnu_incremental_inputs and related sections needed
2752 // for the next run of incremental linking to check what has changed.
2755 Layout::create_incremental_info_sections(Symbol_table
* symtab
)
2757 Incremental_inputs
* incr
= this->incremental_inputs_
;
2759 gold_assert(incr
!= NULL
);
2761 // Create the .gnu_incremental_inputs, _symtab, and _relocs input sections.
2762 incr
->create_data_sections(symtab
);
2764 // Add the .gnu_incremental_inputs section.
2765 const char* incremental_inputs_name
=
2766 this->namepool_
.add(".gnu_incremental_inputs", false, NULL
);
2767 Output_section
* incremental_inputs_os
=
2768 this->make_output_section(incremental_inputs_name
,
2769 elfcpp::SHT_GNU_INCREMENTAL_INPUTS
, 0,
2770 ORDER_INVALID
, false);
2771 incremental_inputs_os
->add_output_section_data(incr
->inputs_section());
2773 // Add the .gnu_incremental_symtab section.
2774 const char* incremental_symtab_name
=
2775 this->namepool_
.add(".gnu_incremental_symtab", false, NULL
);
2776 Output_section
* incremental_symtab_os
=
2777 this->make_output_section(incremental_symtab_name
,
2778 elfcpp::SHT_GNU_INCREMENTAL_SYMTAB
, 0,
2779 ORDER_INVALID
, false);
2780 incremental_symtab_os
->add_output_section_data(incr
->symtab_section());
2781 incremental_symtab_os
->set_entsize(4);
2783 // Add the .gnu_incremental_relocs section.
2784 const char* incremental_relocs_name
=
2785 this->namepool_
.add(".gnu_incremental_relocs", false, NULL
);
2786 Output_section
* incremental_relocs_os
=
2787 this->make_output_section(incremental_relocs_name
,
2788 elfcpp::SHT_GNU_INCREMENTAL_RELOCS
, 0,
2789 ORDER_INVALID
, false);
2790 incremental_relocs_os
->add_output_section_data(incr
->relocs_section());
2791 incremental_relocs_os
->set_entsize(incr
->relocs_entsize());
2793 // Add the .gnu_incremental_got_plt section.
2794 const char* incremental_got_plt_name
=
2795 this->namepool_
.add(".gnu_incremental_got_plt", false, NULL
);
2796 Output_section
* incremental_got_plt_os
=
2797 this->make_output_section(incremental_got_plt_name
,
2798 elfcpp::SHT_GNU_INCREMENTAL_GOT_PLT
, 0,
2799 ORDER_INVALID
, false);
2800 incremental_got_plt_os
->add_output_section_data(incr
->got_plt_section());
2802 // Add the .gnu_incremental_strtab section.
2803 const char* incremental_strtab_name
=
2804 this->namepool_
.add(".gnu_incremental_strtab", false, NULL
);
2805 Output_section
* incremental_strtab_os
= this->make_output_section(incremental_strtab_name
,
2806 elfcpp::SHT_STRTAB
, 0,
2807 ORDER_INVALID
, false);
2808 Output_data_strtab
* strtab_data
=
2809 new Output_data_strtab(incr
->get_stringpool());
2810 incremental_strtab_os
->add_output_section_data(strtab_data
);
2812 incremental_inputs_os
->set_after_input_sections();
2813 incremental_symtab_os
->set_after_input_sections();
2814 incremental_relocs_os
->set_after_input_sections();
2815 incremental_got_plt_os
->set_after_input_sections();
2817 incremental_inputs_os
->set_link_section(incremental_strtab_os
);
2818 incremental_symtab_os
->set_link_section(incremental_inputs_os
);
2819 incremental_relocs_os
->set_link_section(incremental_inputs_os
);
2820 incremental_got_plt_os
->set_link_section(incremental_inputs_os
);
2823 // Return whether SEG1 should be before SEG2 in the output file. This
2824 // is based entirely on the segment type and flags. When this is
2825 // called the segment addresses have normally not yet been set.
2828 Layout::segment_precedes(const Output_segment
* seg1
,
2829 const Output_segment
* seg2
)
2831 elfcpp::Elf_Word type1
= seg1
->type();
2832 elfcpp::Elf_Word type2
= seg2
->type();
2834 // The single PT_PHDR segment is required to precede any loadable
2835 // segment. We simply make it always first.
2836 if (type1
== elfcpp::PT_PHDR
)
2838 gold_assert(type2
!= elfcpp::PT_PHDR
);
2841 if (type2
== elfcpp::PT_PHDR
)
2844 // The single PT_INTERP segment is required to precede any loadable
2845 // segment. We simply make it always second.
2846 if (type1
== elfcpp::PT_INTERP
)
2848 gold_assert(type2
!= elfcpp::PT_INTERP
);
2851 if (type2
== elfcpp::PT_INTERP
)
2854 // We then put PT_LOAD segments before any other segments.
2855 if (type1
== elfcpp::PT_LOAD
&& type2
!= elfcpp::PT_LOAD
)
2857 if (type2
== elfcpp::PT_LOAD
&& type1
!= elfcpp::PT_LOAD
)
2860 // We put the PT_TLS segment last except for the PT_GNU_RELRO
2861 // segment, because that is where the dynamic linker expects to find
2862 // it (this is just for efficiency; other positions would also work
2864 if (type1
== elfcpp::PT_TLS
2865 && type2
!= elfcpp::PT_TLS
2866 && type2
!= elfcpp::PT_GNU_RELRO
)
2868 if (type2
== elfcpp::PT_TLS
2869 && type1
!= elfcpp::PT_TLS
2870 && type1
!= elfcpp::PT_GNU_RELRO
)
2873 // We put the PT_GNU_RELRO segment last, because that is where the
2874 // dynamic linker expects to find it (as with PT_TLS, this is just
2876 if (type1
== elfcpp::PT_GNU_RELRO
&& type2
!= elfcpp::PT_GNU_RELRO
)
2878 if (type2
== elfcpp::PT_GNU_RELRO
&& type1
!= elfcpp::PT_GNU_RELRO
)
2881 const elfcpp::Elf_Word flags1
= seg1
->flags();
2882 const elfcpp::Elf_Word flags2
= seg2
->flags();
2884 // The order of non-PT_LOAD segments is unimportant. We simply sort
2885 // by the numeric segment type and flags values. There should not
2886 // be more than one segment with the same type and flags.
2887 if (type1
!= elfcpp::PT_LOAD
)
2890 return type1
< type2
;
2891 gold_assert(flags1
!= flags2
);
2892 return flags1
< flags2
;
2895 // If the addresses are set already, sort by load address.
2896 if (seg1
->are_addresses_set())
2898 if (!seg2
->are_addresses_set())
2901 unsigned int section_count1
= seg1
->output_section_count();
2902 unsigned int section_count2
= seg2
->output_section_count();
2903 if (section_count1
== 0 && section_count2
> 0)
2905 if (section_count1
> 0 && section_count2
== 0)
2908 uint64_t paddr1
= (seg1
->are_addresses_set()
2910 : seg1
->first_section_load_address());
2911 uint64_t paddr2
= (seg2
->are_addresses_set()
2913 : seg2
->first_section_load_address());
2915 if (paddr1
!= paddr2
)
2916 return paddr1
< paddr2
;
2918 else if (seg2
->are_addresses_set())
2921 // A segment which holds large data comes after a segment which does
2922 // not hold large data.
2923 if (seg1
->is_large_data_segment())
2925 if (!seg2
->is_large_data_segment())
2928 else if (seg2
->is_large_data_segment())
2931 // Otherwise, we sort PT_LOAD segments based on the flags. Readonly
2932 // segments come before writable segments. Then writable segments
2933 // with data come before writable segments without data. Then
2934 // executable segments come before non-executable segments. Then
2935 // the unlikely case of a non-readable segment comes before the
2936 // normal case of a readable segment. If there are multiple
2937 // segments with the same type and flags, we require that the
2938 // address be set, and we sort by virtual address and then physical
2940 if ((flags1
& elfcpp::PF_W
) != (flags2
& elfcpp::PF_W
))
2941 return (flags1
& elfcpp::PF_W
) == 0;
2942 if ((flags1
& elfcpp::PF_W
) != 0
2943 && seg1
->has_any_data_sections() != seg2
->has_any_data_sections())
2944 return seg1
->has_any_data_sections();
2945 if ((flags1
& elfcpp::PF_X
) != (flags2
& elfcpp::PF_X
))
2946 return (flags1
& elfcpp::PF_X
) != 0;
2947 if ((flags1
& elfcpp::PF_R
) != (flags2
& elfcpp::PF_R
))
2948 return (flags1
& elfcpp::PF_R
) == 0;
2950 // We shouldn't get here--we shouldn't create segments which we
2951 // can't distinguish. Unless of course we are using a weird linker
2953 gold_assert(this->script_options_
->saw_phdrs_clause());
2957 // Increase OFF so that it is congruent to ADDR modulo ABI_PAGESIZE.
2960 align_file_offset(off_t off
, uint64_t addr
, uint64_t abi_pagesize
)
2962 uint64_t unsigned_off
= off
;
2963 uint64_t aligned_off
= ((unsigned_off
& ~(abi_pagesize
- 1))
2964 | (addr
& (abi_pagesize
- 1)));
2965 if (aligned_off
< unsigned_off
)
2966 aligned_off
+= abi_pagesize
;
2970 // Set the file offsets of all the segments, and all the sections they
2971 // contain. They have all been created. LOAD_SEG must be be laid out
2972 // first. Return the offset of the data to follow.
2975 Layout::set_segment_offsets(const Target
* target
, Output_segment
* load_seg
,
2976 unsigned int* pshndx
)
2978 // Sort them into the final order. We use a stable sort so that we
2979 // don't randomize the order of indistinguishable segments created
2980 // by linker scripts.
2981 std::stable_sort(this->segment_list_
.begin(), this->segment_list_
.end(),
2982 Layout::Compare_segments(this));
2984 // Find the PT_LOAD segments, and set their addresses and offsets
2985 // and their section's addresses and offsets.
2987 if (parameters
->options().user_set_Ttext())
2988 addr
= parameters
->options().Ttext();
2989 else if (parameters
->options().output_is_position_independent())
2992 addr
= target
->default_text_segment_address();
2995 // If LOAD_SEG is NULL, then the file header and segment headers
2996 // will not be loadable. But they still need to be at offset 0 in
2997 // the file. Set their offsets now.
2998 if (load_seg
== NULL
)
3000 for (Data_list::iterator p
= this->special_output_list_
.begin();
3001 p
!= this->special_output_list_
.end();
3004 off
= align_address(off
, (*p
)->addralign());
3005 (*p
)->set_address_and_file_offset(0, off
);
3006 off
+= (*p
)->data_size();
3010 unsigned int increase_relro
= this->increase_relro_
;
3011 if (this->script_options_
->saw_sections_clause())
3014 const bool check_sections
= parameters
->options().check_sections();
3015 Output_segment
* last_load_segment
= NULL
;
3017 for (Segment_list::iterator p
= this->segment_list_
.begin();
3018 p
!= this->segment_list_
.end();
3021 if ((*p
)->type() == elfcpp::PT_LOAD
)
3023 if (load_seg
!= NULL
&& load_seg
!= *p
)
3027 bool are_addresses_set
= (*p
)->are_addresses_set();
3028 if (are_addresses_set
)
3030 // When it comes to setting file offsets, we care about
3031 // the physical address.
3032 addr
= (*p
)->paddr();
3034 else if (parameters
->options().user_set_Tdata()
3035 && ((*p
)->flags() & elfcpp::PF_W
) != 0
3036 && (!parameters
->options().user_set_Tbss()
3037 || (*p
)->has_any_data_sections()))
3039 addr
= parameters
->options().Tdata();
3040 are_addresses_set
= true;
3042 else if (parameters
->options().user_set_Tbss()
3043 && ((*p
)->flags() & elfcpp::PF_W
) != 0
3044 && !(*p
)->has_any_data_sections())
3046 addr
= parameters
->options().Tbss();
3047 are_addresses_set
= true;
3050 uint64_t orig_addr
= addr
;
3051 uint64_t orig_off
= off
;
3053 uint64_t aligned_addr
= 0;
3054 uint64_t abi_pagesize
= target
->abi_pagesize();
3055 uint64_t common_pagesize
= target
->common_pagesize();
3057 if (!parameters
->options().nmagic()
3058 && !parameters
->options().omagic())
3059 (*p
)->set_minimum_p_align(common_pagesize
);
3061 if (!are_addresses_set
)
3063 // Skip the address forward one page, maintaining the same
3064 // position within the page. This lets us store both segments
3065 // overlapping on a single page in the file, but the loader will
3066 // put them on different pages in memory. We will revisit this
3067 // decision once we know the size of the segment.
3069 addr
= align_address(addr
, (*p
)->maximum_alignment());
3070 aligned_addr
= addr
;
3072 if ((addr
& (abi_pagesize
- 1)) != 0)
3073 addr
= addr
+ abi_pagesize
;
3075 off
= orig_off
+ ((addr
- orig_addr
) & (abi_pagesize
- 1));
3078 if (!parameters
->options().nmagic()
3079 && !parameters
->options().omagic())
3080 off
= align_file_offset(off
, addr
, abi_pagesize
);
3081 else if (load_seg
== NULL
)
3083 // This is -N or -n with a section script which prevents
3084 // us from using a load segment. We need to ensure that
3085 // the file offset is aligned to the alignment of the
3086 // segment. This is because the linker script
3087 // implicitly assumed a zero offset. If we don't align
3088 // here, then the alignment of the sections in the
3089 // linker script may not match the alignment of the
3090 // sections in the set_section_addresses call below,
3091 // causing an error about dot moving backward.
3092 off
= align_address(off
, (*p
)->maximum_alignment());
3095 unsigned int shndx_hold
= *pshndx
;
3096 bool has_relro
= false;
3097 uint64_t new_addr
= (*p
)->set_section_addresses(this, false, addr
,
3102 // Now that we know the size of this segment, we may be able
3103 // to save a page in memory, at the cost of wasting some
3104 // file space, by instead aligning to the start of a new
3105 // page. Here we use the real machine page size rather than
3106 // the ABI mandated page size. If the segment has been
3107 // aligned so that the relro data ends at a page boundary,
3108 // we do not try to realign it.
3110 if (!are_addresses_set
3112 && aligned_addr
!= addr
3113 && !parameters
->incremental())
3115 uint64_t first_off
= (common_pagesize
3117 & (common_pagesize
- 1)));
3118 uint64_t last_off
= new_addr
& (common_pagesize
- 1);
3121 && ((aligned_addr
& ~ (common_pagesize
- 1))
3122 != (new_addr
& ~ (common_pagesize
- 1)))
3123 && first_off
+ last_off
<= common_pagesize
)
3125 *pshndx
= shndx_hold
;
3126 addr
= align_address(aligned_addr
, common_pagesize
);
3127 addr
= align_address(addr
, (*p
)->maximum_alignment());
3128 off
= orig_off
+ ((addr
- orig_addr
) & (abi_pagesize
- 1));
3129 off
= align_file_offset(off
, addr
, abi_pagesize
);
3131 increase_relro
= this->increase_relro_
;
3132 if (this->script_options_
->saw_sections_clause())
3136 new_addr
= (*p
)->set_section_addresses(this, true, addr
,
3145 // Implement --check-sections. We know that the segments
3146 // are sorted by LMA.
3147 if (check_sections
&& last_load_segment
!= NULL
)
3149 gold_assert(last_load_segment
->paddr() <= (*p
)->paddr());
3150 if (last_load_segment
->paddr() + last_load_segment
->memsz()
3153 unsigned long long lb1
= last_load_segment
->paddr();
3154 unsigned long long le1
= lb1
+ last_load_segment
->memsz();
3155 unsigned long long lb2
= (*p
)->paddr();
3156 unsigned long long le2
= lb2
+ (*p
)->memsz();
3157 gold_error(_("load segment overlap [0x%llx -> 0x%llx] and "
3158 "[0x%llx -> 0x%llx]"),
3159 lb1
, le1
, lb2
, le2
);
3162 last_load_segment
= *p
;
3166 // Handle the non-PT_LOAD segments, setting their offsets from their
3167 // section's offsets.
3168 for (Segment_list::iterator p
= this->segment_list_
.begin();
3169 p
!= this->segment_list_
.end();
3172 if ((*p
)->type() != elfcpp::PT_LOAD
)
3173 (*p
)->set_offset((*p
)->type() == elfcpp::PT_GNU_RELRO
3178 // Set the TLS offsets for each section in the PT_TLS segment.
3179 if (this->tls_segment_
!= NULL
)
3180 this->tls_segment_
->set_tls_offsets();
3185 // Set the offsets of all the allocated sections when doing a
3186 // relocatable link. This does the same jobs as set_segment_offsets,
3187 // only for a relocatable link.
3190 Layout::set_relocatable_section_offsets(Output_data
* file_header
,
3191 unsigned int* pshndx
)
3195 file_header
->set_address_and_file_offset(0, 0);
3196 off
+= file_header
->data_size();
3198 for (Section_list::iterator p
= this->section_list_
.begin();
3199 p
!= this->section_list_
.end();
3202 // We skip unallocated sections here, except that group sections
3203 // have to come first.
3204 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) == 0
3205 && (*p
)->type() != elfcpp::SHT_GROUP
)
3208 off
= align_address(off
, (*p
)->addralign());
3210 // The linker script might have set the address.
3211 if (!(*p
)->is_address_valid())
3212 (*p
)->set_address(0);
3213 (*p
)->set_file_offset(off
);
3214 (*p
)->finalize_data_size();
3215 off
+= (*p
)->data_size();
3217 (*p
)->set_out_shndx(*pshndx
);
3224 // Set the file offset of all the sections not associated with a
3228 Layout::set_section_offsets(off_t off
, Layout::Section_offset_pass pass
)
3230 off_t startoff
= off
;
3233 for (Section_list::iterator p
= this->unattached_section_list_
.begin();
3234 p
!= this->unattached_section_list_
.end();
3237 // The symtab section is handled in create_symtab_sections.
3238 if (*p
== this->symtab_section_
)
3241 // If we've already set the data size, don't set it again.
3242 if ((*p
)->is_offset_valid() && (*p
)->is_data_size_valid())
3245 if (pass
== BEFORE_INPUT_SECTIONS_PASS
3246 && (*p
)->requires_postprocessing())
3248 (*p
)->create_postprocessing_buffer();
3249 this->any_postprocessing_sections_
= true;
3252 if (pass
== BEFORE_INPUT_SECTIONS_PASS
3253 && (*p
)->after_input_sections())
3255 else if (pass
== POSTPROCESSING_SECTIONS_PASS
3256 && (!(*p
)->after_input_sections()
3257 || (*p
)->type() == elfcpp::SHT_STRTAB
))
3259 else if (pass
== STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
3260 && (!(*p
)->after_input_sections()
3261 || (*p
)->type() != elfcpp::SHT_STRTAB
))
3264 if (!parameters
->incremental_update())
3266 off
= align_address(off
, (*p
)->addralign());
3267 (*p
)->set_file_offset(off
);
3268 (*p
)->finalize_data_size();
3272 // Incremental update: allocate file space from free list.
3273 (*p
)->pre_finalize_data_size();
3274 off_t current_size
= (*p
)->current_data_size();
3275 off
= this->allocate(current_size
, (*p
)->addralign(), startoff
);
3278 if (is_debugging_enabled(DEBUG_INCREMENTAL
))
3279 this->free_list_
.dump();
3280 gold_assert((*p
)->output_section() != NULL
);
3281 gold_fallback(_("out of patch space for section %s; "
3282 "relink with --incremental-full"),
3283 (*p
)->output_section()->name());
3285 (*p
)->set_file_offset(off
);
3286 (*p
)->finalize_data_size();
3287 if ((*p
)->data_size() > current_size
)
3289 gold_assert((*p
)->output_section() != NULL
);
3290 gold_fallback(_("%s: section changed size; "
3291 "relink with --incremental-full"),
3292 (*p
)->output_section()->name());
3294 gold_debug(DEBUG_INCREMENTAL
,
3295 "set_section_offsets: %08lx %08lx %s",
3296 static_cast<long>(off
),
3297 static_cast<long>((*p
)->data_size()),
3298 ((*p
)->output_section() != NULL
3299 ? (*p
)->output_section()->name() : "(special)"));
3302 off
+= (*p
)->data_size();
3306 // At this point the name must be set.
3307 if (pass
!= STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
)
3308 this->namepool_
.add((*p
)->name(), false, NULL
);
3313 // Set the section indexes of all the sections not associated with a
3317 Layout::set_section_indexes(unsigned int shndx
)
3319 for (Section_list::iterator p
= this->unattached_section_list_
.begin();
3320 p
!= this->unattached_section_list_
.end();
3323 if (!(*p
)->has_out_shndx())
3325 (*p
)->set_out_shndx(shndx
);
3332 // Set the section addresses according to the linker script. This is
3333 // only called when we see a SECTIONS clause. This returns the
3334 // program segment which should hold the file header and segment
3335 // headers, if any. It will return NULL if they should not be in a
3339 Layout::set_section_addresses_from_script(Symbol_table
* symtab
)
3341 Script_sections
* ss
= this->script_options_
->script_sections();
3342 gold_assert(ss
->saw_sections_clause());
3343 return this->script_options_
->set_section_addresses(symtab
, this);
3346 // Place the orphan sections in the linker script.
3349 Layout::place_orphan_sections_in_script()
3351 Script_sections
* ss
= this->script_options_
->script_sections();
3352 gold_assert(ss
->saw_sections_clause());
3354 // Place each orphaned output section in the script.
3355 for (Section_list::iterator p
= this->section_list_
.begin();
3356 p
!= this->section_list_
.end();
3359 if (!(*p
)->found_in_sections_clause())
3360 ss
->place_orphan(*p
);
3364 // Count the local symbols in the regular symbol table and the dynamic
3365 // symbol table, and build the respective string pools.
3368 Layout::count_local_symbols(const Task
* task
,
3369 const Input_objects
* input_objects
)
3371 // First, figure out an upper bound on the number of symbols we'll
3372 // be inserting into each pool. This helps us create the pools with
3373 // the right size, to avoid unnecessary hashtable resizing.
3374 unsigned int symbol_count
= 0;
3375 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
3376 p
!= input_objects
->relobj_end();
3378 symbol_count
+= (*p
)->local_symbol_count();
3380 // Go from "upper bound" to "estimate." We overcount for two
3381 // reasons: we double-count symbols that occur in more than one
3382 // object file, and we count symbols that are dropped from the
3383 // output. Add it all together and assume we overcount by 100%.
3386 // We assume all symbols will go into both the sympool and dynpool.
3387 this->sympool_
.reserve(symbol_count
);
3388 this->dynpool_
.reserve(symbol_count
);
3390 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
3391 p
!= input_objects
->relobj_end();
3394 Task_lock_obj
<Object
> tlo(task
, *p
);
3395 (*p
)->count_local_symbols(&this->sympool_
, &this->dynpool_
);
3399 // Create the symbol table sections. Here we also set the final
3400 // values of the symbols. At this point all the loadable sections are
3401 // fully laid out. SHNUM is the number of sections so far.
3404 Layout::create_symtab_sections(const Input_objects
* input_objects
,
3405 Symbol_table
* symtab
,
3411 if (parameters
->target().get_size() == 32)
3413 symsize
= elfcpp::Elf_sizes
<32>::sym_size
;
3416 else if (parameters
->target().get_size() == 64)
3418 symsize
= elfcpp::Elf_sizes
<64>::sym_size
;
3424 // Compute file offsets relative to the start of the symtab section.
3427 // Save space for the dummy symbol at the start of the section. We
3428 // never bother to write this out--it will just be left as zero.
3430 unsigned int local_symbol_index
= 1;
3432 // Add STT_SECTION symbols for each Output section which needs one.
3433 for (Section_list::iterator p
= this->section_list_
.begin();
3434 p
!= this->section_list_
.end();
3437 if (!(*p
)->needs_symtab_index())
3438 (*p
)->set_symtab_index(-1U);
3441 (*p
)->set_symtab_index(local_symbol_index
);
3442 ++local_symbol_index
;
3447 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
3448 p
!= input_objects
->relobj_end();
3451 unsigned int index
= (*p
)->finalize_local_symbols(local_symbol_index
,
3453 off
+= (index
- local_symbol_index
) * symsize
;
3454 local_symbol_index
= index
;
3457 unsigned int local_symcount
= local_symbol_index
;
3458 gold_assert(static_cast<off_t
>(local_symcount
* symsize
) == off
);
3461 size_t dyn_global_index
;
3463 if (this->dynsym_section_
== NULL
)
3466 dyn_global_index
= 0;
3471 dyn_global_index
= this->dynsym_section_
->info();
3472 off_t locsize
= dyn_global_index
* this->dynsym_section_
->entsize();
3473 dynoff
= this->dynsym_section_
->offset() + locsize
;
3474 dyncount
= (this->dynsym_section_
->data_size() - locsize
) / symsize
;
3475 gold_assert(static_cast<off_t
>(dyncount
* symsize
)
3476 == this->dynsym_section_
->data_size() - locsize
);
3479 off_t global_off
= off
;
3480 off
= symtab
->finalize(off
, dynoff
, dyn_global_index
, dyncount
,
3481 &this->sympool_
, &local_symcount
);
3483 if (!parameters
->options().strip_all())
3485 this->sympool_
.set_string_offsets();
3487 const char* symtab_name
= this->namepool_
.add(".symtab", false, NULL
);
3488 Output_section
* osymtab
= this->make_output_section(symtab_name
,
3492 this->symtab_section_
= osymtab
;
3494 Output_section_data
* pos
= new Output_data_fixed_space(off
, align
,
3496 osymtab
->add_output_section_data(pos
);
3498 // We generate a .symtab_shndx section if we have more than
3499 // SHN_LORESERVE sections. Technically it is possible that we
3500 // don't need one, because it is possible that there are no
3501 // symbols in any of sections with indexes larger than
3502 // SHN_LORESERVE. That is probably unusual, though, and it is
3503 // easier to always create one than to compute section indexes
3504 // twice (once here, once when writing out the symbols).
3505 if (shnum
>= elfcpp::SHN_LORESERVE
)
3507 const char* symtab_xindex_name
= this->namepool_
.add(".symtab_shndx",
3509 Output_section
* osymtab_xindex
=
3510 this->make_output_section(symtab_xindex_name
,
3511 elfcpp::SHT_SYMTAB_SHNDX
, 0,
3512 ORDER_INVALID
, false);
3514 size_t symcount
= off
/ symsize
;
3515 this->symtab_xindex_
= new Output_symtab_xindex(symcount
);
3517 osymtab_xindex
->add_output_section_data(this->symtab_xindex_
);
3519 osymtab_xindex
->set_link_section(osymtab
);
3520 osymtab_xindex
->set_addralign(4);
3521 osymtab_xindex
->set_entsize(4);
3523 osymtab_xindex
->set_after_input_sections();
3525 // This tells the driver code to wait until the symbol table
3526 // has written out before writing out the postprocessing
3527 // sections, including the .symtab_shndx section.
3528 this->any_postprocessing_sections_
= true;
3531 const char* strtab_name
= this->namepool_
.add(".strtab", false, NULL
);
3532 Output_section
* ostrtab
= this->make_output_section(strtab_name
,
3537 Output_section_data
* pstr
= new Output_data_strtab(&this->sympool_
);
3538 ostrtab
->add_output_section_data(pstr
);
3541 if (!parameters
->incremental_update())
3542 symtab_off
= align_address(*poff
, align
);
3545 symtab_off
= this->allocate(off
, align
, *poff
);
3547 gold_fallback(_("out of patch space for symbol table; "
3548 "relink with --incremental-full"));
3549 gold_debug(DEBUG_INCREMENTAL
,
3550 "create_symtab_sections: %08lx %08lx .symtab",
3551 static_cast<long>(symtab_off
),
3552 static_cast<long>(off
));
3555 symtab
->set_file_offset(symtab_off
+ global_off
);
3556 osymtab
->set_file_offset(symtab_off
);
3557 osymtab
->finalize_data_size();
3558 osymtab
->set_link_section(ostrtab
);
3559 osymtab
->set_info(local_symcount
);
3560 osymtab
->set_entsize(symsize
);
3562 if (symtab_off
+ off
> *poff
)
3563 *poff
= symtab_off
+ off
;
3567 // Create the .shstrtab section, which holds the names of the
3568 // sections. At the time this is called, we have created all the
3569 // output sections except .shstrtab itself.
3572 Layout::create_shstrtab()
3574 // FIXME: We don't need to create a .shstrtab section if we are
3575 // stripping everything.
3577 const char* name
= this->namepool_
.add(".shstrtab", false, NULL
);
3579 Output_section
* os
= this->make_output_section(name
, elfcpp::SHT_STRTAB
, 0,
3580 ORDER_INVALID
, false);
3582 if (strcmp(parameters
->options().compress_debug_sections(), "none") != 0)
3584 // We can't write out this section until we've set all the
3585 // section names, and we don't set the names of compressed
3586 // output sections until relocations are complete. FIXME: With
3587 // the current names we use, this is unnecessary.
3588 os
->set_after_input_sections();
3591 Output_section_data
* posd
= new Output_data_strtab(&this->namepool_
);
3592 os
->add_output_section_data(posd
);
3597 // Create the section headers. SIZE is 32 or 64. OFF is the file
3601 Layout::create_shdrs(const Output_section
* shstrtab_section
, off_t
* poff
)
3603 Output_section_headers
* oshdrs
;
3604 oshdrs
= new Output_section_headers(this,
3605 &this->segment_list_
,
3606 &this->section_list_
,
3607 &this->unattached_section_list_
,
3611 if (!parameters
->incremental_update())
3612 off
= align_address(*poff
, oshdrs
->addralign());
3615 oshdrs
->pre_finalize_data_size();
3616 off
= this->allocate(oshdrs
->data_size(), oshdrs
->addralign(), *poff
);
3618 gold_fallback(_("out of patch space for section header table; "
3619 "relink with --incremental-full"));
3620 gold_debug(DEBUG_INCREMENTAL
,
3621 "create_shdrs: %08lx %08lx (section header table)",
3622 static_cast<long>(off
),
3623 static_cast<long>(off
+ oshdrs
->data_size()));
3625 oshdrs
->set_address_and_file_offset(0, off
);
3626 off
+= oshdrs
->data_size();
3629 this->section_headers_
= oshdrs
;
3632 // Count the allocated sections.
3635 Layout::allocated_output_section_count() const
3637 size_t section_count
= 0;
3638 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
3639 p
!= this->segment_list_
.end();
3641 section_count
+= (*p
)->output_section_count();
3642 return section_count
;
3645 // Create the dynamic symbol table.
3648 Layout::create_dynamic_symtab(const Input_objects
* input_objects
,
3649 Symbol_table
* symtab
,
3650 Output_section
** pdynstr
,
3651 unsigned int* plocal_dynamic_count
,
3652 std::vector
<Symbol
*>* pdynamic_symbols
,
3653 Versions
* pversions
)
3655 // Count all the symbols in the dynamic symbol table, and set the
3656 // dynamic symbol indexes.
3658 // Skip symbol 0, which is always all zeroes.
3659 unsigned int index
= 1;
3661 // Add STT_SECTION symbols for each Output section which needs one.
3662 for (Section_list::iterator p
= this->section_list_
.begin();
3663 p
!= this->section_list_
.end();
3666 if (!(*p
)->needs_dynsym_index())
3667 (*p
)->set_dynsym_index(-1U);
3670 (*p
)->set_dynsym_index(index
);
3675 // Count the local symbols that need to go in the dynamic symbol table,
3676 // and set the dynamic symbol indexes.
3677 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
3678 p
!= input_objects
->relobj_end();
3681 unsigned int new_index
= (*p
)->set_local_dynsym_indexes(index
);
3685 unsigned int local_symcount
= index
;
3686 *plocal_dynamic_count
= local_symcount
;
3688 index
= symtab
->set_dynsym_indexes(index
, pdynamic_symbols
,
3689 &this->dynpool_
, pversions
);
3693 const int size
= parameters
->target().get_size();
3696 symsize
= elfcpp::Elf_sizes
<32>::sym_size
;
3699 else if (size
== 64)
3701 symsize
= elfcpp::Elf_sizes
<64>::sym_size
;
3707 // Create the dynamic symbol table section.
3709 Output_section
* dynsym
= this->choose_output_section(NULL
, ".dynsym",
3713 ORDER_DYNAMIC_LINKER
,
3716 // Check for NULL as a linker script may discard .dynsym.
3719 Output_section_data
* odata
= new Output_data_fixed_space(index
* symsize
,
3722 dynsym
->add_output_section_data(odata
);
3724 dynsym
->set_info(local_symcount
);
3725 dynsym
->set_entsize(symsize
);
3726 dynsym
->set_addralign(align
);
3728 this->dynsym_section_
= dynsym
;
3731 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
3734 odyn
->add_section_address(elfcpp::DT_SYMTAB
, dynsym
);
3735 odyn
->add_constant(elfcpp::DT_SYMENT
, symsize
);
3738 // If there are more than SHN_LORESERVE allocated sections, we
3739 // create a .dynsym_shndx section. It is possible that we don't
3740 // need one, because it is possible that there are no dynamic
3741 // symbols in any of the sections with indexes larger than
3742 // SHN_LORESERVE. This is probably unusual, though, and at this
3743 // time we don't know the actual section indexes so it is
3744 // inconvenient to check.
3745 if (this->allocated_output_section_count() >= elfcpp::SHN_LORESERVE
)
3747 Output_section
* dynsym_xindex
=
3748 this->choose_output_section(NULL
, ".dynsym_shndx",
3749 elfcpp::SHT_SYMTAB_SHNDX
,
3751 false, ORDER_DYNAMIC_LINKER
, false);
3753 if (dynsym_xindex
!= NULL
)
3755 this->dynsym_xindex_
= new Output_symtab_xindex(index
);
3757 dynsym_xindex
->add_output_section_data(this->dynsym_xindex_
);
3759 dynsym_xindex
->set_link_section(dynsym
);
3760 dynsym_xindex
->set_addralign(4);
3761 dynsym_xindex
->set_entsize(4);
3763 dynsym_xindex
->set_after_input_sections();
3765 // This tells the driver code to wait until the symbol table
3766 // has written out before writing out the postprocessing
3767 // sections, including the .dynsym_shndx section.
3768 this->any_postprocessing_sections_
= true;
3772 // Create the dynamic string table section.
3774 Output_section
* dynstr
= this->choose_output_section(NULL
, ".dynstr",
3778 ORDER_DYNAMIC_LINKER
,
3783 Output_section_data
* strdata
= new Output_data_strtab(&this->dynpool_
);
3784 dynstr
->add_output_section_data(strdata
);
3787 dynsym
->set_link_section(dynstr
);
3788 if (this->dynamic_section_
!= NULL
)
3789 this->dynamic_section_
->set_link_section(dynstr
);
3793 odyn
->add_section_address(elfcpp::DT_STRTAB
, dynstr
);
3794 odyn
->add_section_size(elfcpp::DT_STRSZ
, dynstr
);
3800 // Create the hash tables.
3802 if (strcmp(parameters
->options().hash_style(), "sysv") == 0
3803 || strcmp(parameters
->options().hash_style(), "both") == 0)
3805 unsigned char* phash
;
3806 unsigned int hashlen
;
3807 Dynobj::create_elf_hash_table(*pdynamic_symbols
, local_symcount
,
3810 Output_section
* hashsec
=
3811 this->choose_output_section(NULL
, ".hash", elfcpp::SHT_HASH
,
3812 elfcpp::SHF_ALLOC
, false,
3813 ORDER_DYNAMIC_LINKER
, false);
3815 Output_section_data
* hashdata
= new Output_data_const_buffer(phash
,
3819 if (hashsec
!= NULL
&& hashdata
!= NULL
)
3820 hashsec
->add_output_section_data(hashdata
);
3822 if (hashsec
!= NULL
)
3825 hashsec
->set_link_section(dynsym
);
3826 hashsec
->set_entsize(4);
3830 odyn
->add_section_address(elfcpp::DT_HASH
, hashsec
);
3833 if (strcmp(parameters
->options().hash_style(), "gnu") == 0
3834 || strcmp(parameters
->options().hash_style(), "both") == 0)
3836 unsigned char* phash
;
3837 unsigned int hashlen
;
3838 Dynobj::create_gnu_hash_table(*pdynamic_symbols
, local_symcount
,
3841 Output_section
* hashsec
=
3842 this->choose_output_section(NULL
, ".gnu.hash", elfcpp::SHT_GNU_HASH
,
3843 elfcpp::SHF_ALLOC
, false,
3844 ORDER_DYNAMIC_LINKER
, false);
3846 Output_section_data
* hashdata
= new Output_data_const_buffer(phash
,
3850 if (hashsec
!= NULL
&& hashdata
!= NULL
)
3851 hashsec
->add_output_section_data(hashdata
);
3853 if (hashsec
!= NULL
)
3856 hashsec
->set_link_section(dynsym
);
3858 // For a 64-bit target, the entries in .gnu.hash do not have
3859 // a uniform size, so we only set the entry size for a
3861 if (parameters
->target().get_size() == 32)
3862 hashsec
->set_entsize(4);
3865 odyn
->add_section_address(elfcpp::DT_GNU_HASH
, hashsec
);
3870 // Assign offsets to each local portion of the dynamic symbol table.
3873 Layout::assign_local_dynsym_offsets(const Input_objects
* input_objects
)
3875 Output_section
* dynsym
= this->dynsym_section_
;
3879 off_t off
= dynsym
->offset();
3881 // Skip the dummy symbol at the start of the section.
3882 off
+= dynsym
->entsize();
3884 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
3885 p
!= input_objects
->relobj_end();
3888 unsigned int count
= (*p
)->set_local_dynsym_offset(off
);
3889 off
+= count
* dynsym
->entsize();
3893 // Create the version sections.
3896 Layout::create_version_sections(const Versions
* versions
,
3897 const Symbol_table
* symtab
,
3898 unsigned int local_symcount
,
3899 const std::vector
<Symbol
*>& dynamic_symbols
,
3900 const Output_section
* dynstr
)
3902 if (!versions
->any_defs() && !versions
->any_needs())
3905 switch (parameters
->size_and_endianness())
3907 #ifdef HAVE_TARGET_32_LITTLE
3908 case Parameters::TARGET_32_LITTLE
:
3909 this->sized_create_version_sections
<32, false>(versions
, symtab
,
3911 dynamic_symbols
, dynstr
);
3914 #ifdef HAVE_TARGET_32_BIG
3915 case Parameters::TARGET_32_BIG
:
3916 this->sized_create_version_sections
<32, true>(versions
, symtab
,
3918 dynamic_symbols
, dynstr
);
3921 #ifdef HAVE_TARGET_64_LITTLE
3922 case Parameters::TARGET_64_LITTLE
:
3923 this->sized_create_version_sections
<64, false>(versions
, symtab
,
3925 dynamic_symbols
, dynstr
);
3928 #ifdef HAVE_TARGET_64_BIG
3929 case Parameters::TARGET_64_BIG
:
3930 this->sized_create_version_sections
<64, true>(versions
, symtab
,
3932 dynamic_symbols
, dynstr
);
3940 // Create the version sections, sized version.
3942 template<int size
, bool big_endian
>
3944 Layout::sized_create_version_sections(
3945 const Versions
* versions
,
3946 const Symbol_table
* symtab
,
3947 unsigned int local_symcount
,
3948 const std::vector
<Symbol
*>& dynamic_symbols
,
3949 const Output_section
* dynstr
)
3951 Output_section
* vsec
= this->choose_output_section(NULL
, ".gnu.version",
3952 elfcpp::SHT_GNU_versym
,
3955 ORDER_DYNAMIC_LINKER
,
3958 // Check for NULL since a linker script may discard this section.
3961 unsigned char* vbuf
;
3963 versions
->symbol_section_contents
<size
, big_endian
>(symtab
,
3969 Output_section_data
* vdata
= new Output_data_const_buffer(vbuf
, vsize
, 2,
3972 vsec
->add_output_section_data(vdata
);
3973 vsec
->set_entsize(2);
3974 vsec
->set_link_section(this->dynsym_section_
);
3977 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
3978 if (odyn
!= NULL
&& vsec
!= NULL
)
3979 odyn
->add_section_address(elfcpp::DT_VERSYM
, vsec
);
3981 if (versions
->any_defs())
3983 Output_section
* vdsec
;
3984 vdsec
= this->choose_output_section(NULL
, ".gnu.version_d",
3985 elfcpp::SHT_GNU_verdef
,
3987 false, ORDER_DYNAMIC_LINKER
, false);
3991 unsigned char* vdbuf
;
3992 unsigned int vdsize
;
3993 unsigned int vdentries
;
3994 versions
->def_section_contents
<size
, big_endian
>(&this->dynpool_
,
3998 Output_section_data
* vddata
=
3999 new Output_data_const_buffer(vdbuf
, vdsize
, 4, "** version defs");
4001 vdsec
->add_output_section_data(vddata
);
4002 vdsec
->set_link_section(dynstr
);
4003 vdsec
->set_info(vdentries
);
4007 odyn
->add_section_address(elfcpp::DT_VERDEF
, vdsec
);
4008 odyn
->add_constant(elfcpp::DT_VERDEFNUM
, vdentries
);
4013 if (versions
->any_needs())
4015 Output_section
* vnsec
;
4016 vnsec
= this->choose_output_section(NULL
, ".gnu.version_r",
4017 elfcpp::SHT_GNU_verneed
,
4019 false, ORDER_DYNAMIC_LINKER
, false);
4023 unsigned char* vnbuf
;
4024 unsigned int vnsize
;
4025 unsigned int vnentries
;
4026 versions
->need_section_contents
<size
, big_endian
>(&this->dynpool_
,
4030 Output_section_data
* vndata
=
4031 new Output_data_const_buffer(vnbuf
, vnsize
, 4, "** version refs");
4033 vnsec
->add_output_section_data(vndata
);
4034 vnsec
->set_link_section(dynstr
);
4035 vnsec
->set_info(vnentries
);
4039 odyn
->add_section_address(elfcpp::DT_VERNEED
, vnsec
);
4040 odyn
->add_constant(elfcpp::DT_VERNEEDNUM
, vnentries
);
4046 // Create the .interp section and PT_INTERP segment.
4049 Layout::create_interp(const Target
* target
)
4051 gold_assert(this->interp_segment_
== NULL
);
4053 const char* interp
= parameters
->options().dynamic_linker();
4056 interp
= target
->dynamic_linker();
4057 gold_assert(interp
!= NULL
);
4060 size_t len
= strlen(interp
) + 1;
4062 Output_section_data
* odata
= new Output_data_const(interp
, len
, 1);
4064 Output_section
* osec
= this->choose_output_section(NULL
, ".interp",
4065 elfcpp::SHT_PROGBITS
,
4067 false, ORDER_INTERP
,
4070 osec
->add_output_section_data(odata
);
4073 // Add dynamic tags for the PLT and the dynamic relocs. This is
4074 // called by the target-specific code. This does nothing if not doing
4077 // USE_REL is true for REL relocs rather than RELA relocs.
4079 // If PLT_GOT is not NULL, then DT_PLTGOT points to it.
4081 // If PLT_REL is not NULL, it is used for DT_PLTRELSZ, and DT_JMPREL,
4082 // and we also set DT_PLTREL. We use PLT_REL's output section, since
4083 // some targets have multiple reloc sections in PLT_REL.
4085 // If DYN_REL is not NULL, it is used for DT_REL/DT_RELA,
4086 // DT_RELSZ/DT_RELASZ, DT_RELENT/DT_RELAENT. Again we use the output
4089 // If ADD_DEBUG is true, we add a DT_DEBUG entry when generating an
4093 Layout::add_target_dynamic_tags(bool use_rel
, const Output_data
* plt_got
,
4094 const Output_data
* plt_rel
,
4095 const Output_data_reloc_generic
* dyn_rel
,
4096 bool add_debug
, bool dynrel_includes_plt
)
4098 Output_data_dynamic
* odyn
= this->dynamic_data_
;
4102 if (plt_got
!= NULL
&& plt_got
->output_section() != NULL
)
4103 odyn
->add_section_address(elfcpp::DT_PLTGOT
, plt_got
);
4105 if (plt_rel
!= NULL
&& plt_rel
->output_section() != NULL
)
4107 odyn
->add_section_size(elfcpp::DT_PLTRELSZ
, plt_rel
->output_section());
4108 odyn
->add_section_address(elfcpp::DT_JMPREL
, plt_rel
->output_section());
4109 odyn
->add_constant(elfcpp::DT_PLTREL
,
4110 use_rel
? elfcpp::DT_REL
: elfcpp::DT_RELA
);
4113 if (dyn_rel
!= NULL
&& dyn_rel
->output_section() != NULL
)
4115 odyn
->add_section_address(use_rel
? elfcpp::DT_REL
: elfcpp::DT_RELA
,
4116 dyn_rel
->output_section());
4118 && plt_rel
->output_section() != NULL
4119 && dynrel_includes_plt
)
4120 odyn
->add_section_size(use_rel
? elfcpp::DT_RELSZ
: elfcpp::DT_RELASZ
,
4121 dyn_rel
->output_section(),
4122 plt_rel
->output_section());
4124 odyn
->add_section_size(use_rel
? elfcpp::DT_RELSZ
: elfcpp::DT_RELASZ
,
4125 dyn_rel
->output_section());
4126 const int size
= parameters
->target().get_size();
4131 rel_tag
= elfcpp::DT_RELENT
;
4133 rel_size
= Reloc_types
<elfcpp::SHT_REL
, 32, false>::reloc_size
;
4134 else if (size
== 64)
4135 rel_size
= Reloc_types
<elfcpp::SHT_REL
, 64, false>::reloc_size
;
4141 rel_tag
= elfcpp::DT_RELAENT
;
4143 rel_size
= Reloc_types
<elfcpp::SHT_RELA
, 32, false>::reloc_size
;
4144 else if (size
== 64)
4145 rel_size
= Reloc_types
<elfcpp::SHT_RELA
, 64, false>::reloc_size
;
4149 odyn
->add_constant(rel_tag
, rel_size
);
4151 if (parameters
->options().combreloc())
4153 size_t c
= dyn_rel
->relative_reloc_count();
4155 odyn
->add_constant((use_rel
4156 ? elfcpp::DT_RELCOUNT
4157 : elfcpp::DT_RELACOUNT
),
4162 if (add_debug
&& !parameters
->options().shared())
4164 // The value of the DT_DEBUG tag is filled in by the dynamic
4165 // linker at run time, and used by the debugger.
4166 odyn
->add_constant(elfcpp::DT_DEBUG
, 0);
4170 // Finish the .dynamic section and PT_DYNAMIC segment.
4173 Layout::finish_dynamic_section(const Input_objects
* input_objects
,
4174 const Symbol_table
* symtab
)
4176 if (!this->script_options_
->saw_phdrs_clause()
4177 && this->dynamic_section_
!= NULL
)
4179 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_DYNAMIC
,
4182 oseg
->add_output_section_to_nonload(this->dynamic_section_
,
4183 elfcpp::PF_R
| elfcpp::PF_W
);
4186 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
4190 for (Input_objects::Dynobj_iterator p
= input_objects
->dynobj_begin();
4191 p
!= input_objects
->dynobj_end();
4194 if (!(*p
)->is_needed() && (*p
)->as_needed())
4196 // This dynamic object was linked with --as-needed, but it
4201 odyn
->add_string(elfcpp::DT_NEEDED
, (*p
)->soname());
4204 if (parameters
->options().shared())
4206 const char* soname
= parameters
->options().soname();
4208 odyn
->add_string(elfcpp::DT_SONAME
, soname
);
4211 Symbol
* sym
= symtab
->lookup(parameters
->options().init());
4212 if (sym
!= NULL
&& sym
->is_defined() && !sym
->is_from_dynobj())
4213 odyn
->add_symbol(elfcpp::DT_INIT
, sym
);
4215 sym
= symtab
->lookup(parameters
->options().fini());
4216 if (sym
!= NULL
&& sym
->is_defined() && !sym
->is_from_dynobj())
4217 odyn
->add_symbol(elfcpp::DT_FINI
, sym
);
4219 // Look for .init_array, .preinit_array and .fini_array by checking
4221 for(Layout::Section_list::const_iterator p
= this->section_list_
.begin();
4222 p
!= this->section_list_
.end();
4224 switch((*p
)->type())
4226 case elfcpp::SHT_FINI_ARRAY
:
4227 odyn
->add_section_address(elfcpp::DT_FINI_ARRAY
, *p
);
4228 odyn
->add_section_size(elfcpp::DT_FINI_ARRAYSZ
, *p
);
4230 case elfcpp::SHT_INIT_ARRAY
:
4231 odyn
->add_section_address(elfcpp::DT_INIT_ARRAY
, *p
);
4232 odyn
->add_section_size(elfcpp::DT_INIT_ARRAYSZ
, *p
);
4234 case elfcpp::SHT_PREINIT_ARRAY
:
4235 odyn
->add_section_address(elfcpp::DT_PREINIT_ARRAY
, *p
);
4236 odyn
->add_section_size(elfcpp::DT_PREINIT_ARRAYSZ
, *p
);
4242 // Add a DT_RPATH entry if needed.
4243 const General_options::Dir_list
& rpath(parameters
->options().rpath());
4246 std::string rpath_val
;
4247 for (General_options::Dir_list::const_iterator p
= rpath
.begin();
4251 if (rpath_val
.empty())
4252 rpath_val
= p
->name();
4255 // Eliminate duplicates.
4256 General_options::Dir_list::const_iterator q
;
4257 for (q
= rpath
.begin(); q
!= p
; ++q
)
4258 if (q
->name() == p
->name())
4263 rpath_val
+= p
->name();
4268 odyn
->add_string(elfcpp::DT_RPATH
, rpath_val
);
4269 if (parameters
->options().enable_new_dtags())
4270 odyn
->add_string(elfcpp::DT_RUNPATH
, rpath_val
);
4273 // Look for text segments that have dynamic relocations.
4274 bool have_textrel
= false;
4275 if (!this->script_options_
->saw_sections_clause())
4277 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
4278 p
!= this->segment_list_
.end();
4281 if ((*p
)->type() == elfcpp::PT_LOAD
4282 && ((*p
)->flags() & elfcpp::PF_W
) == 0
4283 && (*p
)->has_dynamic_reloc())
4285 have_textrel
= true;
4292 // We don't know the section -> segment mapping, so we are
4293 // conservative and just look for readonly sections with
4294 // relocations. If those sections wind up in writable segments,
4295 // then we have created an unnecessary DT_TEXTREL entry.
4296 for (Section_list::const_iterator p
= this->section_list_
.begin();
4297 p
!= this->section_list_
.end();
4300 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) != 0
4301 && ((*p
)->flags() & elfcpp::SHF_WRITE
) == 0
4302 && (*p
)->has_dynamic_reloc())
4304 have_textrel
= true;
4310 if (parameters
->options().filter() != NULL
)
4311 odyn
->add_string(elfcpp::DT_FILTER
, parameters
->options().filter());
4312 if (parameters
->options().any_auxiliary())
4314 for (options::String_set::const_iterator p
=
4315 parameters
->options().auxiliary_begin();
4316 p
!= parameters
->options().auxiliary_end();
4318 odyn
->add_string(elfcpp::DT_AUXILIARY
, *p
);
4321 // Add a DT_FLAGS entry if necessary.
4322 unsigned int flags
= 0;
4325 // Add a DT_TEXTREL for compatibility with older loaders.
4326 odyn
->add_constant(elfcpp::DT_TEXTREL
, 0);
4327 flags
|= elfcpp::DF_TEXTREL
;
4329 if (parameters
->options().text())
4330 gold_error(_("read-only segment has dynamic relocations"));
4331 else if (parameters
->options().warn_shared_textrel()
4332 && parameters
->options().shared())
4333 gold_warning(_("shared library text segment is not shareable"));
4335 if (parameters
->options().shared() && this->has_static_tls())
4336 flags
|= elfcpp::DF_STATIC_TLS
;
4337 if (parameters
->options().origin())
4338 flags
|= elfcpp::DF_ORIGIN
;
4339 if (parameters
->options().Bsymbolic())
4341 flags
|= elfcpp::DF_SYMBOLIC
;
4342 // Add DT_SYMBOLIC for compatibility with older loaders.
4343 odyn
->add_constant(elfcpp::DT_SYMBOLIC
, 0);
4345 if (parameters
->options().now())
4346 flags
|= elfcpp::DF_BIND_NOW
;
4348 odyn
->add_constant(elfcpp::DT_FLAGS
, flags
);
4351 if (parameters
->options().initfirst())
4352 flags
|= elfcpp::DF_1_INITFIRST
;
4353 if (parameters
->options().interpose())
4354 flags
|= elfcpp::DF_1_INTERPOSE
;
4355 if (parameters
->options().loadfltr())
4356 flags
|= elfcpp::DF_1_LOADFLTR
;
4357 if (parameters
->options().nodefaultlib())
4358 flags
|= elfcpp::DF_1_NODEFLIB
;
4359 if (parameters
->options().nodelete())
4360 flags
|= elfcpp::DF_1_NODELETE
;
4361 if (parameters
->options().nodlopen())
4362 flags
|= elfcpp::DF_1_NOOPEN
;
4363 if (parameters
->options().nodump())
4364 flags
|= elfcpp::DF_1_NODUMP
;
4365 if (!parameters
->options().shared())
4366 flags
&= ~(elfcpp::DF_1_INITFIRST
4367 | elfcpp::DF_1_NODELETE
4368 | elfcpp::DF_1_NOOPEN
);
4369 if (parameters
->options().origin())
4370 flags
|= elfcpp::DF_1_ORIGIN
;
4371 if (parameters
->options().now())
4372 flags
|= elfcpp::DF_1_NOW
;
4373 if (parameters
->options().Bgroup())
4374 flags
|= elfcpp::DF_1_GROUP
;
4376 odyn
->add_constant(elfcpp::DT_FLAGS_1
, flags
);
4379 // Set the size of the _DYNAMIC symbol table to be the size of the
4383 Layout::set_dynamic_symbol_size(const Symbol_table
* symtab
)
4385 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
4388 odyn
->finalize_data_size();
4389 if (this->dynamic_symbol_
== NULL
)
4391 off_t data_size
= odyn
->data_size();
4392 const int size
= parameters
->target().get_size();
4394 symtab
->get_sized_symbol
<32>(this->dynamic_symbol_
)->set_symsize(data_size
);
4395 else if (size
== 64)
4396 symtab
->get_sized_symbol
<64>(this->dynamic_symbol_
)->set_symsize(data_size
);
4401 // The mapping of input section name prefixes to output section names.
4402 // In some cases one prefix is itself a prefix of another prefix; in
4403 // such a case the longer prefix must come first. These prefixes are
4404 // based on the GNU linker default ELF linker script.
4406 #define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 }
4407 const Layout::Section_name_mapping
Layout::section_name_mapping
[] =
4409 MAPPING_INIT(".text.", ".text"),
4410 MAPPING_INIT(".rodata.", ".rodata"),
4411 MAPPING_INIT(".data.rel.ro.local", ".data.rel.ro.local"),
4412 MAPPING_INIT(".data.rel.ro", ".data.rel.ro"),
4413 MAPPING_INIT(".data.", ".data"),
4414 MAPPING_INIT(".bss.", ".bss"),
4415 MAPPING_INIT(".tdata.", ".tdata"),
4416 MAPPING_INIT(".tbss.", ".tbss"),
4417 MAPPING_INIT(".init_array.", ".init_array"),
4418 MAPPING_INIT(".fini_array.", ".fini_array"),
4419 MAPPING_INIT(".sdata.", ".sdata"),
4420 MAPPING_INIT(".sbss.", ".sbss"),
4421 // FIXME: In the GNU linker, .sbss2 and .sdata2 are handled
4422 // differently depending on whether it is creating a shared library.
4423 MAPPING_INIT(".sdata2.", ".sdata"),
4424 MAPPING_INIT(".sbss2.", ".sbss"),
4425 MAPPING_INIT(".lrodata.", ".lrodata"),
4426 MAPPING_INIT(".ldata.", ".ldata"),
4427 MAPPING_INIT(".lbss.", ".lbss"),
4428 MAPPING_INIT(".gcc_except_table.", ".gcc_except_table"),
4429 MAPPING_INIT(".gnu.linkonce.d.rel.ro.local.", ".data.rel.ro.local"),
4430 MAPPING_INIT(".gnu.linkonce.d.rel.ro.", ".data.rel.ro"),
4431 MAPPING_INIT(".gnu.linkonce.t.", ".text"),
4432 MAPPING_INIT(".gnu.linkonce.r.", ".rodata"),
4433 MAPPING_INIT(".gnu.linkonce.d.", ".data"),
4434 MAPPING_INIT(".gnu.linkonce.b.", ".bss"),
4435 MAPPING_INIT(".gnu.linkonce.s.", ".sdata"),
4436 MAPPING_INIT(".gnu.linkonce.sb.", ".sbss"),
4437 MAPPING_INIT(".gnu.linkonce.s2.", ".sdata"),
4438 MAPPING_INIT(".gnu.linkonce.sb2.", ".sbss"),
4439 MAPPING_INIT(".gnu.linkonce.wi.", ".debug_info"),
4440 MAPPING_INIT(".gnu.linkonce.td.", ".tdata"),
4441 MAPPING_INIT(".gnu.linkonce.tb.", ".tbss"),
4442 MAPPING_INIT(".gnu.linkonce.lr.", ".lrodata"),
4443 MAPPING_INIT(".gnu.linkonce.l.", ".ldata"),
4444 MAPPING_INIT(".gnu.linkonce.lb.", ".lbss"),
4445 MAPPING_INIT(".ARM.extab", ".ARM.extab"),
4446 MAPPING_INIT(".gnu.linkonce.armextab.", ".ARM.extab"),
4447 MAPPING_INIT(".ARM.exidx", ".ARM.exidx"),
4448 MAPPING_INIT(".gnu.linkonce.armexidx.", ".ARM.exidx"),
4452 const int Layout::section_name_mapping_count
=
4453 (sizeof(Layout::section_name_mapping
)
4454 / sizeof(Layout::section_name_mapping
[0]));
4456 // Choose the output section name to use given an input section name.
4457 // Set *PLEN to the length of the name. *PLEN is initialized to the
4461 Layout::output_section_name(const Relobj
* relobj
, const char* name
,
4464 // gcc 4.3 generates the following sorts of section names when it
4465 // needs a section name specific to a function:
4471 // .data.rel.local.FN
4473 // .data.rel.ro.local.FN
4480 // The GNU linker maps all of those to the part before the .FN,
4481 // except that .data.rel.local.FN is mapped to .data, and
4482 // .data.rel.ro.local.FN is mapped to .data.rel.ro. The sections
4483 // beginning with .data.rel.ro.local are grouped together.
4485 // For an anonymous namespace, the string FN can contain a '.'.
4487 // Also of interest: .rodata.strN.N, .rodata.cstN, both of which the
4488 // GNU linker maps to .rodata.
4490 // The .data.rel.ro sections are used with -z relro. The sections
4491 // are recognized by name. We use the same names that the GNU
4492 // linker does for these sections.
4494 // It is hard to handle this in a principled way, so we don't even
4495 // try. We use a table of mappings. If the input section name is
4496 // not found in the table, we simply use it as the output section
4499 const Section_name_mapping
* psnm
= section_name_mapping
;
4500 for (int i
= 0; i
< section_name_mapping_count
; ++i
, ++psnm
)
4502 if (strncmp(name
, psnm
->from
, psnm
->fromlen
) == 0)
4504 *plen
= psnm
->tolen
;
4509 // As an additional complication, .ctors sections are output in
4510 // either .ctors or .init_array sections, and .dtors sections are
4511 // output in either .dtors or .fini_array sections.
4512 if (is_prefix_of(".ctors.", name
) || is_prefix_of(".dtors.", name
))
4514 if (parameters
->options().ctors_in_init_array())
4517 return name
[1] == 'c' ? ".init_array" : ".fini_array";
4522 return name
[1] == 'c' ? ".ctors" : ".dtors";
4525 if (parameters
->options().ctors_in_init_array()
4526 && (strcmp(name
, ".ctors") == 0 || strcmp(name
, ".dtors") == 0))
4528 // To make .init_array/.fini_array work with gcc we must exclude
4529 // .ctors and .dtors sections from the crtbegin and crtend
4532 || (!Layout::match_file_name(relobj
, "crtbegin")
4533 && !Layout::match_file_name(relobj
, "crtend")))
4536 return name
[1] == 'c' ? ".init_array" : ".fini_array";
4543 // Return true if RELOBJ is an input file whose base name matches
4544 // FILE_NAME. The base name must have an extension of ".o", and must
4545 // be exactly FILE_NAME.o or FILE_NAME, one character, ".o". This is
4546 // to match crtbegin.o as well as crtbeginS.o without getting confused
4547 // by other possibilities. Overall matching the file name this way is
4548 // a dreadful hack, but the GNU linker does it in order to better
4549 // support gcc, and we need to be compatible.
4552 Layout::match_file_name(const Relobj
* relobj
, const char* match
)
4554 const std::string
& file_name(relobj
->name());
4555 const char* base_name
= lbasename(file_name
.c_str());
4556 size_t match_len
= strlen(match
);
4557 if (strncmp(base_name
, match
, match_len
) != 0)
4559 size_t base_len
= strlen(base_name
);
4560 if (base_len
!= match_len
+ 2 && base_len
!= match_len
+ 3)
4562 return memcmp(base_name
+ base_len
- 2, ".o", 2) == 0;
4565 // Check if a comdat group or .gnu.linkonce section with the given
4566 // NAME is selected for the link. If there is already a section,
4567 // *KEPT_SECTION is set to point to the existing section and the
4568 // function returns false. Otherwise, OBJECT, SHNDX, IS_COMDAT, and
4569 // IS_GROUP_NAME are recorded for this NAME in the layout object,
4570 // *KEPT_SECTION is set to the internal copy and the function returns
4574 Layout::find_or_add_kept_section(const std::string
& name
,
4579 Kept_section
** kept_section
)
4581 // It's normal to see a couple of entries here, for the x86 thunk
4582 // sections. If we see more than a few, we're linking a C++
4583 // program, and we resize to get more space to minimize rehashing.
4584 if (this->signatures_
.size() > 4
4585 && !this->resized_signatures_
)
4587 reserve_unordered_map(&this->signatures_
,
4588 this->number_of_input_files_
* 64);
4589 this->resized_signatures_
= true;
4592 Kept_section candidate
;
4593 std::pair
<Signatures::iterator
, bool> ins
=
4594 this->signatures_
.insert(std::make_pair(name
, candidate
));
4596 if (kept_section
!= NULL
)
4597 *kept_section
= &ins
.first
->second
;
4600 // This is the first time we've seen this signature.
4601 ins
.first
->second
.set_object(object
);
4602 ins
.first
->second
.set_shndx(shndx
);
4604 ins
.first
->second
.set_is_comdat();
4606 ins
.first
->second
.set_is_group_name();
4610 // We have already seen this signature.
4612 if (ins
.first
->second
.is_group_name())
4614 // We've already seen a real section group with this signature.
4615 // If the kept group is from a plugin object, and we're in the
4616 // replacement phase, accept the new one as a replacement.
4617 if (ins
.first
->second
.object() == NULL
4618 && parameters
->options().plugins()->in_replacement_phase())
4620 ins
.first
->second
.set_object(object
);
4621 ins
.first
->second
.set_shndx(shndx
);
4626 else if (is_group_name
)
4628 // This is a real section group, and we've already seen a
4629 // linkonce section with this signature. Record that we've seen
4630 // a section group, and don't include this section group.
4631 ins
.first
->second
.set_is_group_name();
4636 // We've already seen a linkonce section and this is a linkonce
4637 // section. These don't block each other--this may be the same
4638 // symbol name with different section types.
4643 // Store the allocated sections into the section list.
4646 Layout::get_allocated_sections(Section_list
* section_list
) const
4648 for (Section_list::const_iterator p
= this->section_list_
.begin();
4649 p
!= this->section_list_
.end();
4651 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) != 0)
4652 section_list
->push_back(*p
);
4655 // Create an output segment.
4658 Layout::make_output_segment(elfcpp::Elf_Word type
, elfcpp::Elf_Word flags
)
4660 gold_assert(!parameters
->options().relocatable());
4661 Output_segment
* oseg
= new Output_segment(type
, flags
);
4662 this->segment_list_
.push_back(oseg
);
4664 if (type
== elfcpp::PT_TLS
)
4665 this->tls_segment_
= oseg
;
4666 else if (type
== elfcpp::PT_GNU_RELRO
)
4667 this->relro_segment_
= oseg
;
4668 else if (type
== elfcpp::PT_INTERP
)
4669 this->interp_segment_
= oseg
;
4674 // Return the file offset of the normal symbol table.
4677 Layout::symtab_section_offset() const
4679 if (this->symtab_section_
!= NULL
)
4680 return this->symtab_section_
->offset();
4684 // Return the section index of the normal symbol table. It may have
4685 // been stripped by the -s/--strip-all option.
4688 Layout::symtab_section_shndx() const
4690 if (this->symtab_section_
!= NULL
)
4691 return this->symtab_section_
->out_shndx();
4695 // Write out the Output_sections. Most won't have anything to write,
4696 // since most of the data will come from input sections which are
4697 // handled elsewhere. But some Output_sections do have Output_data.
4700 Layout::write_output_sections(Output_file
* of
) const
4702 for (Section_list::const_iterator p
= this->section_list_
.begin();
4703 p
!= this->section_list_
.end();
4706 if (!(*p
)->after_input_sections())
4711 // Write out data not associated with a section or the symbol table.
4714 Layout::write_data(const Symbol_table
* symtab
, Output_file
* of
) const
4716 if (!parameters
->options().strip_all())
4718 const Output_section
* symtab_section
= this->symtab_section_
;
4719 for (Section_list::const_iterator p
= this->section_list_
.begin();
4720 p
!= this->section_list_
.end();
4723 if ((*p
)->needs_symtab_index())
4725 gold_assert(symtab_section
!= NULL
);
4726 unsigned int index
= (*p
)->symtab_index();
4727 gold_assert(index
> 0 && index
!= -1U);
4728 off_t off
= (symtab_section
->offset()
4729 + index
* symtab_section
->entsize());
4730 symtab
->write_section_symbol(*p
, this->symtab_xindex_
, of
, off
);
4735 const Output_section
* dynsym_section
= this->dynsym_section_
;
4736 for (Section_list::const_iterator p
= this->section_list_
.begin();
4737 p
!= this->section_list_
.end();
4740 if ((*p
)->needs_dynsym_index())
4742 gold_assert(dynsym_section
!= NULL
);
4743 unsigned int index
= (*p
)->dynsym_index();
4744 gold_assert(index
> 0 && index
!= -1U);
4745 off_t off
= (dynsym_section
->offset()
4746 + index
* dynsym_section
->entsize());
4747 symtab
->write_section_symbol(*p
, this->dynsym_xindex_
, of
, off
);
4751 // Write out the Output_data which are not in an Output_section.
4752 for (Data_list::const_iterator p
= this->special_output_list_
.begin();
4753 p
!= this->special_output_list_
.end();
4758 // Write out the Output_sections which can only be written after the
4759 // input sections are complete.
4762 Layout::write_sections_after_input_sections(Output_file
* of
)
4764 // Determine the final section offsets, and thus the final output
4765 // file size. Note we finalize the .shstrab last, to allow the
4766 // after_input_section sections to modify their section-names before
4768 if (this->any_postprocessing_sections_
)
4770 off_t off
= this->output_file_size_
;
4771 off
= this->set_section_offsets(off
, POSTPROCESSING_SECTIONS_PASS
);
4773 // Now that we've finalized the names, we can finalize the shstrab.
4775 this->set_section_offsets(off
,
4776 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
);
4778 if (off
> this->output_file_size_
)
4781 this->output_file_size_
= off
;
4785 for (Section_list::const_iterator p
= this->section_list_
.begin();
4786 p
!= this->section_list_
.end();
4789 if ((*p
)->after_input_sections())
4793 this->section_headers_
->write(of
);
4796 // If the build ID requires computing a checksum, do so here, and
4797 // write it out. We compute a checksum over the entire file because
4798 // that is simplest.
4801 Layout::write_build_id(Output_file
* of
) const
4803 if (this->build_id_note_
== NULL
)
4806 const unsigned char* iv
= of
->get_input_view(0, this->output_file_size_
);
4808 unsigned char* ov
= of
->get_output_view(this->build_id_note_
->offset(),
4809 this->build_id_note_
->data_size());
4811 const char* style
= parameters
->options().build_id();
4812 if (strcmp(style
, "sha1") == 0)
4815 sha1_init_ctx(&ctx
);
4816 sha1_process_bytes(iv
, this->output_file_size_
, &ctx
);
4817 sha1_finish_ctx(&ctx
, ov
);
4819 else if (strcmp(style
, "md5") == 0)
4823 md5_process_bytes(iv
, this->output_file_size_
, &ctx
);
4824 md5_finish_ctx(&ctx
, ov
);
4829 of
->write_output_view(this->build_id_note_
->offset(),
4830 this->build_id_note_
->data_size(),
4833 of
->free_input_view(0, this->output_file_size_
, iv
);
4836 // Write out a binary file. This is called after the link is
4837 // complete. IN is the temporary output file we used to generate the
4838 // ELF code. We simply walk through the segments, read them from
4839 // their file offset in IN, and write them to their load address in
4840 // the output file. FIXME: with a bit more work, we could support
4841 // S-records and/or Intel hex format here.
4844 Layout::write_binary(Output_file
* in
) const
4846 gold_assert(parameters
->options().oformat_enum()
4847 == General_options::OBJECT_FORMAT_BINARY
);
4849 // Get the size of the binary file.
4850 uint64_t max_load_address
= 0;
4851 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
4852 p
!= this->segment_list_
.end();
4855 if ((*p
)->type() == elfcpp::PT_LOAD
&& (*p
)->filesz() > 0)
4857 uint64_t max_paddr
= (*p
)->paddr() + (*p
)->filesz();
4858 if (max_paddr
> max_load_address
)
4859 max_load_address
= max_paddr
;
4863 Output_file
out(parameters
->options().output_file_name());
4864 out
.open(max_load_address
);
4866 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
4867 p
!= this->segment_list_
.end();
4870 if ((*p
)->type() == elfcpp::PT_LOAD
&& (*p
)->filesz() > 0)
4872 const unsigned char* vin
= in
->get_input_view((*p
)->offset(),
4874 unsigned char* vout
= out
.get_output_view((*p
)->paddr(),
4876 memcpy(vout
, vin
, (*p
)->filesz());
4877 out
.write_output_view((*p
)->paddr(), (*p
)->filesz(), vout
);
4878 in
->free_input_view((*p
)->offset(), (*p
)->filesz(), vin
);
4885 // Print the output sections to the map file.
4888 Layout::print_to_mapfile(Mapfile
* mapfile
) const
4890 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
4891 p
!= this->segment_list_
.end();
4893 (*p
)->print_sections_to_mapfile(mapfile
);
4896 // Print statistical information to stderr. This is used for --stats.
4899 Layout::print_stats() const
4901 this->namepool_
.print_stats("section name pool");
4902 this->sympool_
.print_stats("output symbol name pool");
4903 this->dynpool_
.print_stats("dynamic name pool");
4905 for (Section_list::const_iterator p
= this->section_list_
.begin();
4906 p
!= this->section_list_
.end();
4908 (*p
)->print_merge_stats();
4911 // Write_sections_task methods.
4913 // We can always run this task.
4916 Write_sections_task::is_runnable()
4921 // We need to unlock both OUTPUT_SECTIONS_BLOCKER and FINAL_BLOCKER
4925 Write_sections_task::locks(Task_locker
* tl
)
4927 tl
->add(this, this->output_sections_blocker_
);
4928 tl
->add(this, this->final_blocker_
);
4931 // Run the task--write out the data.
4934 Write_sections_task::run(Workqueue
*)
4936 this->layout_
->write_output_sections(this->of_
);
4939 // Write_data_task methods.
4941 // We can always run this task.
4944 Write_data_task::is_runnable()
4949 // We need to unlock FINAL_BLOCKER when finished.
4952 Write_data_task::locks(Task_locker
* tl
)
4954 tl
->add(this, this->final_blocker_
);
4957 // Run the task--write out the data.
4960 Write_data_task::run(Workqueue
*)
4962 this->layout_
->write_data(this->symtab_
, this->of_
);
4965 // Write_symbols_task methods.
4967 // We can always run this task.
4970 Write_symbols_task::is_runnable()
4975 // We need to unlock FINAL_BLOCKER when finished.
4978 Write_symbols_task::locks(Task_locker
* tl
)
4980 tl
->add(this, this->final_blocker_
);
4983 // Run the task--write out the symbols.
4986 Write_symbols_task::run(Workqueue
*)
4988 this->symtab_
->write_globals(this->sympool_
, this->dynpool_
,
4989 this->layout_
->symtab_xindex(),
4990 this->layout_
->dynsym_xindex(), this->of_
);
4993 // Write_after_input_sections_task methods.
4995 // We can only run this task after the input sections have completed.
4998 Write_after_input_sections_task::is_runnable()
5000 if (this->input_sections_blocker_
->is_blocked())
5001 return this->input_sections_blocker_
;
5005 // We need to unlock FINAL_BLOCKER when finished.
5008 Write_after_input_sections_task::locks(Task_locker
* tl
)
5010 tl
->add(this, this->final_blocker_
);
5016 Write_after_input_sections_task::run(Workqueue
*)
5018 this->layout_
->write_sections_after_input_sections(this->of_
);
5021 // Close_task_runner methods.
5023 // Run the task--close the file.
5026 Close_task_runner::run(Workqueue
*, const Task
*)
5028 // If we need to compute a checksum for the BUILD if, we do so here.
5029 this->layout_
->write_build_id(this->of_
);
5031 // If we've been asked to create a binary file, we do so here.
5032 if (this->options_
->oformat_enum() != General_options::OBJECT_FORMAT_ELF
)
5033 this->layout_
->write_binary(this->of_
);
5038 // Instantiate the templates we need. We could use the configure
5039 // script to restrict this to only the ones for implemented targets.
5041 #ifdef HAVE_TARGET_32_LITTLE
5044 Layout::init_fixed_output_section
<32, false>(
5046 elfcpp::Shdr
<32, false>& shdr
);
5049 #ifdef HAVE_TARGET_32_BIG
5052 Layout::init_fixed_output_section
<32, true>(
5054 elfcpp::Shdr
<32, true>& shdr
);
5057 #ifdef HAVE_TARGET_64_LITTLE
5060 Layout::init_fixed_output_section
<64, false>(
5062 elfcpp::Shdr
<64, false>& shdr
);
5065 #ifdef HAVE_TARGET_64_BIG
5068 Layout::init_fixed_output_section
<64, true>(
5070 elfcpp::Shdr
<64, true>& shdr
);
5073 #ifdef HAVE_TARGET_32_LITTLE
5076 Layout::layout
<32, false>(Sized_relobj_file
<32, false>* object
,
5079 const elfcpp::Shdr
<32, false>& shdr
,
5080 unsigned int, unsigned int, off_t
*);
5083 #ifdef HAVE_TARGET_32_BIG
5086 Layout::layout
<32, true>(Sized_relobj_file
<32, true>* object
,
5089 const elfcpp::Shdr
<32, true>& shdr
,
5090 unsigned int, unsigned int, off_t
*);
5093 #ifdef HAVE_TARGET_64_LITTLE
5096 Layout::layout
<64, false>(Sized_relobj_file
<64, false>* object
,
5099 const elfcpp::Shdr
<64, false>& shdr
,
5100 unsigned int, unsigned int, off_t
*);
5103 #ifdef HAVE_TARGET_64_BIG
5106 Layout::layout
<64, true>(Sized_relobj_file
<64, true>* object
,
5109 const elfcpp::Shdr
<64, true>& shdr
,
5110 unsigned int, unsigned int, off_t
*);
5113 #ifdef HAVE_TARGET_32_LITTLE
5116 Layout::layout_reloc
<32, false>(Sized_relobj_file
<32, false>* object
,
5117 unsigned int reloc_shndx
,
5118 const elfcpp::Shdr
<32, false>& shdr
,
5119 Output_section
* data_section
,
5120 Relocatable_relocs
* rr
);
5123 #ifdef HAVE_TARGET_32_BIG
5126 Layout::layout_reloc
<32, true>(Sized_relobj_file
<32, true>* object
,
5127 unsigned int reloc_shndx
,
5128 const elfcpp::Shdr
<32, true>& shdr
,
5129 Output_section
* data_section
,
5130 Relocatable_relocs
* rr
);
5133 #ifdef HAVE_TARGET_64_LITTLE
5136 Layout::layout_reloc
<64, false>(Sized_relobj_file
<64, false>* object
,
5137 unsigned int reloc_shndx
,
5138 const elfcpp::Shdr
<64, false>& shdr
,
5139 Output_section
* data_section
,
5140 Relocatable_relocs
* rr
);
5143 #ifdef HAVE_TARGET_64_BIG
5146 Layout::layout_reloc
<64, true>(Sized_relobj_file
<64, true>* object
,
5147 unsigned int reloc_shndx
,
5148 const elfcpp::Shdr
<64, true>& shdr
,
5149 Output_section
* data_section
,
5150 Relocatable_relocs
* rr
);
5153 #ifdef HAVE_TARGET_32_LITTLE
5156 Layout::layout_group
<32, false>(Symbol_table
* symtab
,
5157 Sized_relobj_file
<32, false>* object
,
5159 const char* group_section_name
,
5160 const char* signature
,
5161 const elfcpp::Shdr
<32, false>& shdr
,
5162 elfcpp::Elf_Word flags
,
5163 std::vector
<unsigned int>* shndxes
);
5166 #ifdef HAVE_TARGET_32_BIG
5169 Layout::layout_group
<32, true>(Symbol_table
* symtab
,
5170 Sized_relobj_file
<32, true>* object
,
5172 const char* group_section_name
,
5173 const char* signature
,
5174 const elfcpp::Shdr
<32, true>& shdr
,
5175 elfcpp::Elf_Word flags
,
5176 std::vector
<unsigned int>* shndxes
);
5179 #ifdef HAVE_TARGET_64_LITTLE
5182 Layout::layout_group
<64, false>(Symbol_table
* symtab
,
5183 Sized_relobj_file
<64, false>* object
,
5185 const char* group_section_name
,
5186 const char* signature
,
5187 const elfcpp::Shdr
<64, false>& shdr
,
5188 elfcpp::Elf_Word flags
,
5189 std::vector
<unsigned int>* shndxes
);
5192 #ifdef HAVE_TARGET_64_BIG
5195 Layout::layout_group
<64, true>(Symbol_table
* symtab
,
5196 Sized_relobj_file
<64, true>* object
,
5198 const char* group_section_name
,
5199 const char* signature
,
5200 const elfcpp::Shdr
<64, true>& shdr
,
5201 elfcpp::Elf_Word flags
,
5202 std::vector
<unsigned int>* shndxes
);
5205 #ifdef HAVE_TARGET_32_LITTLE
5208 Layout::layout_eh_frame
<32, false>(Sized_relobj_file
<32, false>* object
,
5209 const unsigned char* symbols
,
5211 const unsigned char* symbol_names
,
5212 off_t symbol_names_size
,
5214 const elfcpp::Shdr
<32, false>& shdr
,
5215 unsigned int reloc_shndx
,
5216 unsigned int reloc_type
,
5220 #ifdef HAVE_TARGET_32_BIG
5223 Layout::layout_eh_frame
<32, true>(Sized_relobj_file
<32, true>* object
,
5224 const unsigned char* symbols
,
5226 const unsigned char* symbol_names
,
5227 off_t symbol_names_size
,
5229 const elfcpp::Shdr
<32, true>& shdr
,
5230 unsigned int reloc_shndx
,
5231 unsigned int reloc_type
,
5235 #ifdef HAVE_TARGET_64_LITTLE
5238 Layout::layout_eh_frame
<64, false>(Sized_relobj_file
<64, false>* object
,
5239 const unsigned char* symbols
,
5241 const unsigned char* symbol_names
,
5242 off_t symbol_names_size
,
5244 const elfcpp::Shdr
<64, false>& shdr
,
5245 unsigned int reloc_shndx
,
5246 unsigned int reloc_type
,
5250 #ifdef HAVE_TARGET_64_BIG
5253 Layout::layout_eh_frame
<64, true>(Sized_relobj_file
<64, true>* object
,
5254 const unsigned char* symbols
,
5256 const unsigned char* symbol_names
,
5257 off_t symbol_names_size
,
5259 const elfcpp::Shdr
<64, true>& shdr
,
5260 unsigned int reloc_shndx
,
5261 unsigned int reloc_type
,
5265 } // End namespace gold.