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 this->dynamic_symbol_
=
1790 symtab
->define_in_output_data("_DYNAMIC", NULL
, Symbol_table::PREDEFINED
,
1791 this->dynamic_section_
, 0, 0,
1792 elfcpp::STT_OBJECT
, elfcpp::STB_LOCAL
,
1793 elfcpp::STV_HIDDEN
, 0, false, false);
1795 this->dynamic_data_
= new Output_data_dynamic(&this->dynpool_
);
1797 this->dynamic_section_
->add_output_section_data(this->dynamic_data_
);
1800 // For each output section whose name can be represented as C symbol,
1801 // define __start and __stop symbols for the section. This is a GNU
1805 Layout::define_section_symbols(Symbol_table
* symtab
)
1807 for (Section_list::const_iterator p
= this->section_list_
.begin();
1808 p
!= this->section_list_
.end();
1811 const char* const name
= (*p
)->name();
1812 if (is_cident(name
))
1814 const std::string
name_string(name
);
1815 const std::string
start_name(cident_section_start_prefix
1817 const std::string
stop_name(cident_section_stop_prefix
1820 symtab
->define_in_output_data(start_name
.c_str(),
1822 Symbol_table::PREDEFINED
,
1828 elfcpp::STV_DEFAULT
,
1830 false, // offset_is_from_end
1831 true); // only_if_ref
1833 symtab
->define_in_output_data(stop_name
.c_str(),
1835 Symbol_table::PREDEFINED
,
1841 elfcpp::STV_DEFAULT
,
1843 true, // offset_is_from_end
1844 true); // only_if_ref
1849 // Define symbols for group signatures.
1852 Layout::define_group_signatures(Symbol_table
* symtab
)
1854 for (Group_signatures::iterator p
= this->group_signatures_
.begin();
1855 p
!= this->group_signatures_
.end();
1858 Symbol
* sym
= symtab
->lookup(p
->signature
, NULL
);
1860 p
->section
->set_info_symndx(sym
);
1863 // Force the name of the group section to the group
1864 // signature, and use the group's section symbol as the
1865 // signature symbol.
1866 if (strcmp(p
->section
->name(), p
->signature
) != 0)
1868 const char* name
= this->namepool_
.add(p
->signature
,
1870 p
->section
->set_name(name
);
1872 p
->section
->set_needs_symtab_index();
1873 p
->section
->set_info_section_symndx(p
->section
);
1877 this->group_signatures_
.clear();
1880 // Find the first read-only PT_LOAD segment, creating one if
1884 Layout::find_first_load_seg()
1886 Output_segment
* best
= NULL
;
1887 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
1888 p
!= this->segment_list_
.end();
1891 if ((*p
)->type() == elfcpp::PT_LOAD
1892 && ((*p
)->flags() & elfcpp::PF_R
) != 0
1893 && (parameters
->options().omagic()
1894 || ((*p
)->flags() & elfcpp::PF_W
) == 0))
1896 if (best
== NULL
|| this->segment_precedes(*p
, best
))
1903 gold_assert(!this->script_options_
->saw_phdrs_clause());
1905 Output_segment
* load_seg
= this->make_output_segment(elfcpp::PT_LOAD
,
1910 // Save states of all current output segments. Store saved states
1911 // in SEGMENT_STATES.
1914 Layout::save_segments(Segment_states
* segment_states
)
1916 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
1917 p
!= this->segment_list_
.end();
1920 Output_segment
* segment
= *p
;
1922 Output_segment
* copy
= new Output_segment(*segment
);
1923 (*segment_states
)[segment
] = copy
;
1927 // Restore states of output segments and delete any segment not found in
1931 Layout::restore_segments(const Segment_states
* segment_states
)
1933 // Go through the segment list and remove any segment added in the
1935 this->tls_segment_
= NULL
;
1936 this->relro_segment_
= NULL
;
1937 Segment_list::iterator list_iter
= this->segment_list_
.begin();
1938 while (list_iter
!= this->segment_list_
.end())
1940 Output_segment
* segment
= *list_iter
;
1941 Segment_states::const_iterator states_iter
=
1942 segment_states
->find(segment
);
1943 if (states_iter
!= segment_states
->end())
1945 const Output_segment
* copy
= states_iter
->second
;
1946 // Shallow copy to restore states.
1949 // Also fix up TLS and RELRO segment pointers as appropriate.
1950 if (segment
->type() == elfcpp::PT_TLS
)
1951 this->tls_segment_
= segment
;
1952 else if (segment
->type() == elfcpp::PT_GNU_RELRO
)
1953 this->relro_segment_
= segment
;
1959 list_iter
= this->segment_list_
.erase(list_iter
);
1960 // This is a segment created during section layout. It should be
1961 // safe to remove it since we should have removed all pointers to it.
1967 // Clean up after relaxation so that sections can be laid out again.
1970 Layout::clean_up_after_relaxation()
1972 // Restore the segments to point state just prior to the relaxation loop.
1973 Script_sections
* script_section
= this->script_options_
->script_sections();
1974 script_section
->release_segments();
1975 this->restore_segments(this->segment_states_
);
1977 // Reset section addresses and file offsets
1978 for (Section_list::iterator p
= this->section_list_
.begin();
1979 p
!= this->section_list_
.end();
1982 (*p
)->restore_states();
1984 // If an input section changes size because of relaxation,
1985 // we need to adjust the section offsets of all input sections.
1986 // after such a section.
1987 if ((*p
)->section_offsets_need_adjustment())
1988 (*p
)->adjust_section_offsets();
1990 (*p
)->reset_address_and_file_offset();
1993 // Reset special output object address and file offsets.
1994 for (Data_list::iterator p
= this->special_output_list_
.begin();
1995 p
!= this->special_output_list_
.end();
1997 (*p
)->reset_address_and_file_offset();
1999 // A linker script may have created some output section data objects.
2000 // They are useless now.
2001 for (Output_section_data_list::const_iterator p
=
2002 this->script_output_section_data_list_
.begin();
2003 p
!= this->script_output_section_data_list_
.end();
2006 this->script_output_section_data_list_
.clear();
2009 // Prepare for relaxation.
2012 Layout::prepare_for_relaxation()
2014 // Create an relaxation debug check if in debugging mode.
2015 if (is_debugging_enabled(DEBUG_RELAXATION
))
2016 this->relaxation_debug_check_
= new Relaxation_debug_check();
2018 // Save segment states.
2019 this->segment_states_
= new Segment_states();
2020 this->save_segments(this->segment_states_
);
2022 for(Section_list::const_iterator p
= this->section_list_
.begin();
2023 p
!= this->section_list_
.end();
2025 (*p
)->save_states();
2027 if (is_debugging_enabled(DEBUG_RELAXATION
))
2028 this->relaxation_debug_check_
->check_output_data_for_reset_values(
2029 this->section_list_
, this->special_output_list_
);
2031 // Also enable recording of output section data from scripts.
2032 this->record_output_section_data_from_script_
= true;
2035 // Relaxation loop body: If target has no relaxation, this runs only once
2036 // Otherwise, the target relaxation hook is called at the end of
2037 // each iteration. If the hook returns true, it means re-layout of
2038 // section is required.
2040 // The number of segments created by a linking script without a PHDRS
2041 // clause may be affected by section sizes and alignments. There is
2042 // a remote chance that relaxation causes different number of PT_LOAD
2043 // segments are created and sections are attached to different segments.
2044 // Therefore, we always throw away all segments created during section
2045 // layout. In order to be able to restart the section layout, we keep
2046 // a copy of the segment list right before the relaxation loop and use
2047 // that to restore the segments.
2049 // PASS is the current relaxation pass number.
2050 // SYMTAB is a symbol table.
2051 // PLOAD_SEG is the address of a pointer for the load segment.
2052 // PHDR_SEG is a pointer to the PHDR segment.
2053 // SEGMENT_HEADERS points to the output segment header.
2054 // FILE_HEADER points to the output file header.
2055 // PSHNDX is the address to store the output section index.
2058 Layout::relaxation_loop_body(
2061 Symbol_table
* symtab
,
2062 Output_segment
** pload_seg
,
2063 Output_segment
* phdr_seg
,
2064 Output_segment_headers
* segment_headers
,
2065 Output_file_header
* file_header
,
2066 unsigned int* pshndx
)
2068 // If this is not the first iteration, we need to clean up after
2069 // relaxation so that we can lay out the sections again.
2071 this->clean_up_after_relaxation();
2073 // If there is a SECTIONS clause, put all the input sections into
2074 // the required order.
2075 Output_segment
* load_seg
;
2076 if (this->script_options_
->saw_sections_clause())
2077 load_seg
= this->set_section_addresses_from_script(symtab
);
2078 else if (parameters
->options().relocatable())
2081 load_seg
= this->find_first_load_seg();
2083 if (parameters
->options().oformat_enum()
2084 != General_options::OBJECT_FORMAT_ELF
)
2087 // If the user set the address of the text segment, that may not be
2088 // compatible with putting the segment headers and file headers into
2090 if (parameters
->options().user_set_Ttext())
2093 gold_assert(phdr_seg
== NULL
2095 || this->script_options_
->saw_sections_clause());
2097 // If the address of the load segment we found has been set by
2098 // --section-start rather than by a script, then adjust the VMA and
2099 // LMA downward if possible to include the file and section headers.
2100 uint64_t header_gap
= 0;
2101 if (load_seg
!= NULL
2102 && load_seg
->are_addresses_set()
2103 && !this->script_options_
->saw_sections_clause()
2104 && !parameters
->options().relocatable())
2106 file_header
->finalize_data_size();
2107 segment_headers
->finalize_data_size();
2108 size_t sizeof_headers
= (file_header
->data_size()
2109 + segment_headers
->data_size());
2110 const uint64_t abi_pagesize
= target
->abi_pagesize();
2111 uint64_t hdr_paddr
= load_seg
->paddr() - sizeof_headers
;
2112 hdr_paddr
&= ~(abi_pagesize
- 1);
2113 uint64_t subtract
= load_seg
->paddr() - hdr_paddr
;
2114 if (load_seg
->paddr() < subtract
|| load_seg
->vaddr() < subtract
)
2118 load_seg
->set_addresses(load_seg
->vaddr() - subtract
,
2119 load_seg
->paddr() - subtract
);
2120 header_gap
= subtract
- sizeof_headers
;
2124 // Lay out the segment headers.
2125 if (!parameters
->options().relocatable())
2127 gold_assert(segment_headers
!= NULL
);
2128 if (header_gap
!= 0 && load_seg
!= NULL
)
2130 Output_data_zero_fill
* z
= new Output_data_zero_fill(header_gap
, 1);
2131 load_seg
->add_initial_output_data(z
);
2133 if (load_seg
!= NULL
)
2134 load_seg
->add_initial_output_data(segment_headers
);
2135 if (phdr_seg
!= NULL
)
2136 phdr_seg
->add_initial_output_data(segment_headers
);
2139 // Lay out the file header.
2140 if (load_seg
!= NULL
)
2141 load_seg
->add_initial_output_data(file_header
);
2143 if (this->script_options_
->saw_phdrs_clause()
2144 && !parameters
->options().relocatable())
2146 // Support use of FILEHDRS and PHDRS attachments in a PHDRS
2147 // clause in a linker script.
2148 Script_sections
* ss
= this->script_options_
->script_sections();
2149 ss
->put_headers_in_phdrs(file_header
, segment_headers
);
2152 // We set the output section indexes in set_segment_offsets and
2153 // set_section_indexes.
2156 // Set the file offsets of all the segments, and all the sections
2159 if (!parameters
->options().relocatable())
2160 off
= this->set_segment_offsets(target
, load_seg
, pshndx
);
2162 off
= this->set_relocatable_section_offsets(file_header
, pshndx
);
2164 // Verify that the dummy relaxation does not change anything.
2165 if (is_debugging_enabled(DEBUG_RELAXATION
))
2168 this->relaxation_debug_check_
->read_sections(this->section_list_
);
2170 this->relaxation_debug_check_
->verify_sections(this->section_list_
);
2173 *pload_seg
= load_seg
;
2177 // Search the list of patterns and find the postion of the given section
2178 // name in the output section. If the section name matches a glob
2179 // pattern and a non-glob name, then the non-glob position takes
2180 // precedence. Return 0 if no match is found.
2183 Layout::find_section_order_index(const std::string
& section_name
)
2185 Unordered_map
<std::string
, unsigned int>::iterator map_it
;
2186 map_it
= this->input_section_position_
.find(section_name
);
2187 if (map_it
!= this->input_section_position_
.end())
2188 return map_it
->second
;
2190 // Absolute match failed. Linear search the glob patterns.
2191 std::vector
<std::string
>::iterator it
;
2192 for (it
= this->input_section_glob_
.begin();
2193 it
!= this->input_section_glob_
.end();
2196 if (fnmatch((*it
).c_str(), section_name
.c_str(), FNM_NOESCAPE
) == 0)
2198 map_it
= this->input_section_position_
.find(*it
);
2199 gold_assert(map_it
!= this->input_section_position_
.end());
2200 return map_it
->second
;
2206 // Read the sequence of input sections from the file specified with
2207 // --section-ordering-file.
2210 Layout::read_layout_from_file()
2212 const char* filename
= parameters
->options().section_ordering_file();
2218 gold_fatal(_("unable to open --section-ordering-file file %s: %s"),
2219 filename
, strerror(errno
));
2221 std::getline(in
, line
); // this chops off the trailing \n, if any
2222 unsigned int position
= 1;
2226 if (!line
.empty() && line
[line
.length() - 1] == '\r') // Windows
2227 line
.resize(line
.length() - 1);
2228 // Ignore comments, beginning with '#'
2231 std::getline(in
, line
);
2234 this->input_section_position_
[line
] = position
;
2235 // Store all glob patterns in a vector.
2236 if (is_wildcard_string(line
.c_str()))
2237 this->input_section_glob_
.push_back(line
);
2239 std::getline(in
, line
);
2243 // Finalize the layout. When this is called, we have created all the
2244 // output sections and all the output segments which are based on
2245 // input sections. We have several things to do, and we have to do
2246 // them in the right order, so that we get the right results correctly
2249 // 1) Finalize the list of output segments and create the segment
2252 // 2) Finalize the dynamic symbol table and associated sections.
2254 // 3) Determine the final file offset of all the output segments.
2256 // 4) Determine the final file offset of all the SHF_ALLOC output
2259 // 5) Create the symbol table sections and the section name table
2262 // 6) Finalize the symbol table: set symbol values to their final
2263 // value and make a final determination of which symbols are going
2264 // into the output symbol table.
2266 // 7) Create the section table header.
2268 // 8) Determine the final file offset of all the output sections which
2269 // are not SHF_ALLOC, including the section table header.
2271 // 9) Finalize the ELF file header.
2273 // This function returns the size of the output file.
2276 Layout::finalize(const Input_objects
* input_objects
, Symbol_table
* symtab
,
2277 Target
* target
, const Task
* task
)
2279 target
->finalize_sections(this, input_objects
, symtab
);
2281 this->count_local_symbols(task
, input_objects
);
2283 this->link_stabs_sections();
2285 Output_segment
* phdr_seg
= NULL
;
2286 if (!parameters
->options().relocatable() && !parameters
->doing_static_link())
2288 // There was a dynamic object in the link. We need to create
2289 // some information for the dynamic linker.
2291 // Create the PT_PHDR segment which will hold the program
2293 if (!this->script_options_
->saw_phdrs_clause())
2294 phdr_seg
= this->make_output_segment(elfcpp::PT_PHDR
, elfcpp::PF_R
);
2296 // Create the dynamic symbol table, including the hash table.
2297 Output_section
* dynstr
;
2298 std::vector
<Symbol
*> dynamic_symbols
;
2299 unsigned int local_dynamic_count
;
2300 Versions
versions(*this->script_options()->version_script_info(),
2302 this->create_dynamic_symtab(input_objects
, symtab
, &dynstr
,
2303 &local_dynamic_count
, &dynamic_symbols
,
2306 // Create the .interp section to hold the name of the
2307 // interpreter, and put it in a PT_INTERP segment. Don't do it
2308 // if we saw a .interp section in an input file.
2309 if ((!parameters
->options().shared()
2310 || parameters
->options().dynamic_linker() != NULL
)
2311 && this->interp_segment_
== NULL
)
2312 this->create_interp(target
);
2314 // Finish the .dynamic section to hold the dynamic data, and put
2315 // it in a PT_DYNAMIC segment.
2316 this->finish_dynamic_section(input_objects
, symtab
);
2318 // We should have added everything we need to the dynamic string
2320 this->dynpool_
.set_string_offsets();
2322 // Create the version sections. We can't do this until the
2323 // dynamic string table is complete.
2324 this->create_version_sections(&versions
, symtab
, local_dynamic_count
,
2325 dynamic_symbols
, dynstr
);
2327 // Set the size of the _DYNAMIC symbol. We can't do this until
2328 // after we call create_version_sections.
2329 this->set_dynamic_symbol_size(symtab
);
2332 // Create segment headers.
2333 Output_segment_headers
* segment_headers
=
2334 (parameters
->options().relocatable()
2336 : new Output_segment_headers(this->segment_list_
));
2338 // Lay out the file header.
2339 Output_file_header
* file_header
= new Output_file_header(target
, symtab
,
2342 this->special_output_list_
.push_back(file_header
);
2343 if (segment_headers
!= NULL
)
2344 this->special_output_list_
.push_back(segment_headers
);
2346 // Find approriate places for orphan output sections if we are using
2348 if (this->script_options_
->saw_sections_clause())
2349 this->place_orphan_sections_in_script();
2351 Output_segment
* load_seg
;
2356 // Take a snapshot of the section layout as needed.
2357 if (target
->may_relax())
2358 this->prepare_for_relaxation();
2360 // Run the relaxation loop to lay out sections.
2363 off
= this->relaxation_loop_body(pass
, target
, symtab
, &load_seg
,
2364 phdr_seg
, segment_headers
, file_header
,
2368 while (target
->may_relax()
2369 && target
->relax(pass
, input_objects
, symtab
, this, task
));
2371 // Set the file offsets of all the non-data sections we've seen so
2372 // far which don't have to wait for the input sections. We need
2373 // this in order to finalize local symbols in non-allocated
2375 off
= this->set_section_offsets(off
, BEFORE_INPUT_SECTIONS_PASS
);
2377 // Set the section indexes of all unallocated sections seen so far,
2378 // in case any of them are somehow referenced by a symbol.
2379 shndx
= this->set_section_indexes(shndx
);
2381 // Create the symbol table sections.
2382 this->create_symtab_sections(input_objects
, symtab
, shndx
, &off
);
2383 if (!parameters
->doing_static_link())
2384 this->assign_local_dynsym_offsets(input_objects
);
2386 // Process any symbol assignments from a linker script. This must
2387 // be called after the symbol table has been finalized.
2388 this->script_options_
->finalize_symbols(symtab
, this);
2390 // Create the incremental inputs sections.
2391 if (this->incremental_inputs_
)
2393 this->incremental_inputs_
->finalize();
2394 this->create_incremental_info_sections(symtab
);
2397 // Create the .shstrtab section.
2398 Output_section
* shstrtab_section
= this->create_shstrtab();
2400 // Set the file offsets of the rest of the non-data sections which
2401 // don't have to wait for the input sections.
2402 off
= this->set_section_offsets(off
, BEFORE_INPUT_SECTIONS_PASS
);
2404 // Now that all sections have been created, set the section indexes
2405 // for any sections which haven't been done yet.
2406 shndx
= this->set_section_indexes(shndx
);
2408 // Create the section table header.
2409 this->create_shdrs(shstrtab_section
, &off
);
2411 // If there are no sections which require postprocessing, we can
2412 // handle the section names now, and avoid a resize later.
2413 if (!this->any_postprocessing_sections_
)
2415 off
= this->set_section_offsets(off
,
2416 POSTPROCESSING_SECTIONS_PASS
);
2418 this->set_section_offsets(off
,
2419 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
);
2422 file_header
->set_section_info(this->section_headers_
, shstrtab_section
);
2424 // Now we know exactly where everything goes in the output file
2425 // (except for non-allocated sections which require postprocessing).
2426 Output_data::layout_complete();
2428 this->output_file_size_
= off
;
2433 // Create a note header following the format defined in the ELF ABI.
2434 // NAME is the name, NOTE_TYPE is the type, SECTION_NAME is the name
2435 // of the section to create, DESCSZ is the size of the descriptor.
2436 // ALLOCATE is true if the section should be allocated in memory.
2437 // This returns the new note section. It sets *TRAILING_PADDING to
2438 // the number of trailing zero bytes required.
2441 Layout::create_note(const char* name
, int note_type
,
2442 const char* section_name
, size_t descsz
,
2443 bool allocate
, size_t* trailing_padding
)
2445 // Authorities all agree that the values in a .note field should
2446 // be aligned on 4-byte boundaries for 32-bit binaries. However,
2447 // they differ on what the alignment is for 64-bit binaries.
2448 // The GABI says unambiguously they take 8-byte alignment:
2449 // http://sco.com/developers/gabi/latest/ch5.pheader.html#note_section
2450 // Other documentation says alignment should always be 4 bytes:
2451 // http://www.netbsd.org/docs/kernel/elf-notes.html#note-format
2452 // GNU ld and GNU readelf both support the latter (at least as of
2453 // version 2.16.91), and glibc always generates the latter for
2454 // .note.ABI-tag (as of version 1.6), so that's the one we go with
2456 #ifdef GABI_FORMAT_FOR_DOTNOTE_SECTION // This is not defined by default.
2457 const int size
= parameters
->target().get_size();
2459 const int size
= 32;
2462 // The contents of the .note section.
2463 size_t namesz
= strlen(name
) + 1;
2464 size_t aligned_namesz
= align_address(namesz
, size
/ 8);
2465 size_t aligned_descsz
= align_address(descsz
, size
/ 8);
2467 size_t notehdrsz
= 3 * (size
/ 8) + aligned_namesz
;
2469 unsigned char* buffer
= new unsigned char[notehdrsz
];
2470 memset(buffer
, 0, notehdrsz
);
2472 bool is_big_endian
= parameters
->target().is_big_endian();
2478 elfcpp::Swap
<32, false>::writeval(buffer
, namesz
);
2479 elfcpp::Swap
<32, false>::writeval(buffer
+ 4, descsz
);
2480 elfcpp::Swap
<32, false>::writeval(buffer
+ 8, note_type
);
2484 elfcpp::Swap
<32, true>::writeval(buffer
, namesz
);
2485 elfcpp::Swap
<32, true>::writeval(buffer
+ 4, descsz
);
2486 elfcpp::Swap
<32, true>::writeval(buffer
+ 8, note_type
);
2489 else if (size
== 64)
2493 elfcpp::Swap
<64, false>::writeval(buffer
, namesz
);
2494 elfcpp::Swap
<64, false>::writeval(buffer
+ 8, descsz
);
2495 elfcpp::Swap
<64, false>::writeval(buffer
+ 16, note_type
);
2499 elfcpp::Swap
<64, true>::writeval(buffer
, namesz
);
2500 elfcpp::Swap
<64, true>::writeval(buffer
+ 8, descsz
);
2501 elfcpp::Swap
<64, true>::writeval(buffer
+ 16, note_type
);
2507 memcpy(buffer
+ 3 * (size
/ 8), name
, namesz
);
2509 elfcpp::Elf_Xword flags
= 0;
2510 Output_section_order order
= ORDER_INVALID
;
2513 flags
= elfcpp::SHF_ALLOC
;
2514 order
= ORDER_RO_NOTE
;
2516 Output_section
* os
= this->choose_output_section(NULL
, section_name
,
2518 flags
, false, order
, false);
2522 Output_section_data
* posd
= new Output_data_const_buffer(buffer
, notehdrsz
,
2525 os
->add_output_section_data(posd
);
2527 *trailing_padding
= aligned_descsz
- descsz
;
2532 // For an executable or shared library, create a note to record the
2533 // version of gold used to create the binary.
2536 Layout::create_gold_note()
2538 if (parameters
->options().relocatable()
2539 || parameters
->incremental_update())
2542 std::string desc
= std::string("gold ") + gold::get_version_string();
2544 size_t trailing_padding
;
2545 Output_section
* os
= this->create_note("GNU", elfcpp::NT_GNU_GOLD_VERSION
,
2546 ".note.gnu.gold-version", desc
.size(),
2547 false, &trailing_padding
);
2551 Output_section_data
* posd
= new Output_data_const(desc
, 4);
2552 os
->add_output_section_data(posd
);
2554 if (trailing_padding
> 0)
2556 posd
= new Output_data_zero_fill(trailing_padding
, 0);
2557 os
->add_output_section_data(posd
);
2561 // Record whether the stack should be executable. This can be set
2562 // from the command line using the -z execstack or -z noexecstack
2563 // options. Otherwise, if any input file has a .note.GNU-stack
2564 // section with the SHF_EXECINSTR flag set, the stack should be
2565 // executable. Otherwise, if at least one input file a
2566 // .note.GNU-stack section, and some input file has no .note.GNU-stack
2567 // section, we use the target default for whether the stack should be
2568 // executable. Otherwise, we don't generate a stack note. When
2569 // generating a object file, we create a .note.GNU-stack section with
2570 // the appropriate marking. When generating an executable or shared
2571 // library, we create a PT_GNU_STACK segment.
2574 Layout::create_executable_stack_info()
2576 bool is_stack_executable
;
2577 if (parameters
->options().is_execstack_set())
2578 is_stack_executable
= parameters
->options().is_stack_executable();
2579 else if (!this->input_with_gnu_stack_note_
)
2583 if (this->input_requires_executable_stack_
)
2584 is_stack_executable
= true;
2585 else if (this->input_without_gnu_stack_note_
)
2586 is_stack_executable
=
2587 parameters
->target().is_default_stack_executable();
2589 is_stack_executable
= false;
2592 if (parameters
->options().relocatable())
2594 const char* name
= this->namepool_
.add(".note.GNU-stack", false, NULL
);
2595 elfcpp::Elf_Xword flags
= 0;
2596 if (is_stack_executable
)
2597 flags
|= elfcpp::SHF_EXECINSTR
;
2598 this->make_output_section(name
, elfcpp::SHT_PROGBITS
, flags
,
2599 ORDER_INVALID
, false);
2603 if (this->script_options_
->saw_phdrs_clause())
2605 int flags
= elfcpp::PF_R
| elfcpp::PF_W
;
2606 if (is_stack_executable
)
2607 flags
|= elfcpp::PF_X
;
2608 this->make_output_segment(elfcpp::PT_GNU_STACK
, flags
);
2612 // If --build-id was used, set up the build ID note.
2615 Layout::create_build_id()
2617 if (!parameters
->options().user_set_build_id())
2620 const char* style
= parameters
->options().build_id();
2621 if (strcmp(style
, "none") == 0)
2624 // Set DESCSZ to the size of the note descriptor. When possible,
2625 // set DESC to the note descriptor contents.
2628 if (strcmp(style
, "md5") == 0)
2630 else if (strcmp(style
, "sha1") == 0)
2632 else if (strcmp(style
, "uuid") == 0)
2634 const size_t uuidsz
= 128 / 8;
2636 char buffer
[uuidsz
];
2637 memset(buffer
, 0, uuidsz
);
2639 int descriptor
= open_descriptor(-1, "/dev/urandom", O_RDONLY
);
2641 gold_error(_("--build-id=uuid failed: could not open /dev/urandom: %s"),
2645 ssize_t got
= ::read(descriptor
, buffer
, uuidsz
);
2646 release_descriptor(descriptor
, true);
2648 gold_error(_("/dev/urandom: read failed: %s"), strerror(errno
));
2649 else if (static_cast<size_t>(got
) != uuidsz
)
2650 gold_error(_("/dev/urandom: expected %zu bytes, got %zd bytes"),
2654 desc
.assign(buffer
, uuidsz
);
2657 else if (strncmp(style
, "0x", 2) == 0)
2660 const char* p
= style
+ 2;
2663 if (hex_p(p
[0]) && hex_p(p
[1]))
2665 char c
= (hex_value(p
[0]) << 4) | hex_value(p
[1]);
2669 else if (*p
== '-' || *p
== ':')
2672 gold_fatal(_("--build-id argument '%s' not a valid hex number"),
2675 descsz
= desc
.size();
2678 gold_fatal(_("unrecognized --build-id argument '%s'"), style
);
2681 size_t trailing_padding
;
2682 Output_section
* os
= this->create_note("GNU", elfcpp::NT_GNU_BUILD_ID
,
2683 ".note.gnu.build-id", descsz
, true,
2690 // We know the value already, so we fill it in now.
2691 gold_assert(desc
.size() == descsz
);
2693 Output_section_data
* posd
= new Output_data_const(desc
, 4);
2694 os
->add_output_section_data(posd
);
2696 if (trailing_padding
!= 0)
2698 posd
= new Output_data_zero_fill(trailing_padding
, 0);
2699 os
->add_output_section_data(posd
);
2704 // We need to compute a checksum after we have completed the
2706 gold_assert(trailing_padding
== 0);
2707 this->build_id_note_
= new Output_data_zero_fill(descsz
, 4);
2708 os
->add_output_section_data(this->build_id_note_
);
2712 // If we have both .stabXX and .stabXXstr sections, then the sh_link
2713 // field of the former should point to the latter. I'm not sure who
2714 // started this, but the GNU linker does it, and some tools depend
2718 Layout::link_stabs_sections()
2720 if (!this->have_stabstr_section_
)
2723 for (Section_list::iterator p
= this->section_list_
.begin();
2724 p
!= this->section_list_
.end();
2727 if ((*p
)->type() != elfcpp::SHT_STRTAB
)
2730 const char* name
= (*p
)->name();
2731 if (strncmp(name
, ".stab", 5) != 0)
2734 size_t len
= strlen(name
);
2735 if (strcmp(name
+ len
- 3, "str") != 0)
2738 std::string
stab_name(name
, len
- 3);
2739 Output_section
* stab_sec
;
2740 stab_sec
= this->find_output_section(stab_name
.c_str());
2741 if (stab_sec
!= NULL
)
2742 stab_sec
->set_link_section(*p
);
2746 // Create .gnu_incremental_inputs and related sections needed
2747 // for the next run of incremental linking to check what has changed.
2750 Layout::create_incremental_info_sections(Symbol_table
* symtab
)
2752 Incremental_inputs
* incr
= this->incremental_inputs_
;
2754 gold_assert(incr
!= NULL
);
2756 // Create the .gnu_incremental_inputs, _symtab, and _relocs input sections.
2757 incr
->create_data_sections(symtab
);
2759 // Add the .gnu_incremental_inputs section.
2760 const char* incremental_inputs_name
=
2761 this->namepool_
.add(".gnu_incremental_inputs", false, NULL
);
2762 Output_section
* incremental_inputs_os
=
2763 this->make_output_section(incremental_inputs_name
,
2764 elfcpp::SHT_GNU_INCREMENTAL_INPUTS
, 0,
2765 ORDER_INVALID
, false);
2766 incremental_inputs_os
->add_output_section_data(incr
->inputs_section());
2768 // Add the .gnu_incremental_symtab section.
2769 const char* incremental_symtab_name
=
2770 this->namepool_
.add(".gnu_incremental_symtab", false, NULL
);
2771 Output_section
* incremental_symtab_os
=
2772 this->make_output_section(incremental_symtab_name
,
2773 elfcpp::SHT_GNU_INCREMENTAL_SYMTAB
, 0,
2774 ORDER_INVALID
, false);
2775 incremental_symtab_os
->add_output_section_data(incr
->symtab_section());
2776 incremental_symtab_os
->set_entsize(4);
2778 // Add the .gnu_incremental_relocs section.
2779 const char* incremental_relocs_name
=
2780 this->namepool_
.add(".gnu_incremental_relocs", false, NULL
);
2781 Output_section
* incremental_relocs_os
=
2782 this->make_output_section(incremental_relocs_name
,
2783 elfcpp::SHT_GNU_INCREMENTAL_RELOCS
, 0,
2784 ORDER_INVALID
, false);
2785 incremental_relocs_os
->add_output_section_data(incr
->relocs_section());
2786 incremental_relocs_os
->set_entsize(incr
->relocs_entsize());
2788 // Add the .gnu_incremental_got_plt section.
2789 const char* incremental_got_plt_name
=
2790 this->namepool_
.add(".gnu_incremental_got_plt", false, NULL
);
2791 Output_section
* incremental_got_plt_os
=
2792 this->make_output_section(incremental_got_plt_name
,
2793 elfcpp::SHT_GNU_INCREMENTAL_GOT_PLT
, 0,
2794 ORDER_INVALID
, false);
2795 incremental_got_plt_os
->add_output_section_data(incr
->got_plt_section());
2797 // Add the .gnu_incremental_strtab section.
2798 const char* incremental_strtab_name
=
2799 this->namepool_
.add(".gnu_incremental_strtab", false, NULL
);
2800 Output_section
* incremental_strtab_os
= this->make_output_section(incremental_strtab_name
,
2801 elfcpp::SHT_STRTAB
, 0,
2802 ORDER_INVALID
, false);
2803 Output_data_strtab
* strtab_data
=
2804 new Output_data_strtab(incr
->get_stringpool());
2805 incremental_strtab_os
->add_output_section_data(strtab_data
);
2807 incremental_inputs_os
->set_after_input_sections();
2808 incremental_symtab_os
->set_after_input_sections();
2809 incremental_relocs_os
->set_after_input_sections();
2810 incremental_got_plt_os
->set_after_input_sections();
2812 incremental_inputs_os
->set_link_section(incremental_strtab_os
);
2813 incremental_symtab_os
->set_link_section(incremental_inputs_os
);
2814 incremental_relocs_os
->set_link_section(incremental_inputs_os
);
2815 incremental_got_plt_os
->set_link_section(incremental_inputs_os
);
2818 // Return whether SEG1 should be before SEG2 in the output file. This
2819 // is based entirely on the segment type and flags. When this is
2820 // called the segment addresses have normally not yet been set.
2823 Layout::segment_precedes(const Output_segment
* seg1
,
2824 const Output_segment
* seg2
)
2826 elfcpp::Elf_Word type1
= seg1
->type();
2827 elfcpp::Elf_Word type2
= seg2
->type();
2829 // The single PT_PHDR segment is required to precede any loadable
2830 // segment. We simply make it always first.
2831 if (type1
== elfcpp::PT_PHDR
)
2833 gold_assert(type2
!= elfcpp::PT_PHDR
);
2836 if (type2
== elfcpp::PT_PHDR
)
2839 // The single PT_INTERP segment is required to precede any loadable
2840 // segment. We simply make it always second.
2841 if (type1
== elfcpp::PT_INTERP
)
2843 gold_assert(type2
!= elfcpp::PT_INTERP
);
2846 if (type2
== elfcpp::PT_INTERP
)
2849 // We then put PT_LOAD segments before any other segments.
2850 if (type1
== elfcpp::PT_LOAD
&& type2
!= elfcpp::PT_LOAD
)
2852 if (type2
== elfcpp::PT_LOAD
&& type1
!= elfcpp::PT_LOAD
)
2855 // We put the PT_TLS segment last except for the PT_GNU_RELRO
2856 // segment, because that is where the dynamic linker expects to find
2857 // it (this is just for efficiency; other positions would also work
2859 if (type1
== elfcpp::PT_TLS
2860 && type2
!= elfcpp::PT_TLS
2861 && type2
!= elfcpp::PT_GNU_RELRO
)
2863 if (type2
== elfcpp::PT_TLS
2864 && type1
!= elfcpp::PT_TLS
2865 && type1
!= elfcpp::PT_GNU_RELRO
)
2868 // We put the PT_GNU_RELRO segment last, because that is where the
2869 // dynamic linker expects to find it (as with PT_TLS, this is just
2871 if (type1
== elfcpp::PT_GNU_RELRO
&& type2
!= elfcpp::PT_GNU_RELRO
)
2873 if (type2
== elfcpp::PT_GNU_RELRO
&& type1
!= elfcpp::PT_GNU_RELRO
)
2876 const elfcpp::Elf_Word flags1
= seg1
->flags();
2877 const elfcpp::Elf_Word flags2
= seg2
->flags();
2879 // The order of non-PT_LOAD segments is unimportant. We simply sort
2880 // by the numeric segment type and flags values. There should not
2881 // be more than one segment with the same type and flags.
2882 if (type1
!= elfcpp::PT_LOAD
)
2885 return type1
< type2
;
2886 gold_assert(flags1
!= flags2
);
2887 return flags1
< flags2
;
2890 // If the addresses are set already, sort by load address.
2891 if (seg1
->are_addresses_set())
2893 if (!seg2
->are_addresses_set())
2896 unsigned int section_count1
= seg1
->output_section_count();
2897 unsigned int section_count2
= seg2
->output_section_count();
2898 if (section_count1
== 0 && section_count2
> 0)
2900 if (section_count1
> 0 && section_count2
== 0)
2903 uint64_t paddr1
= (seg1
->are_addresses_set()
2905 : seg1
->first_section_load_address());
2906 uint64_t paddr2
= (seg2
->are_addresses_set()
2908 : seg2
->first_section_load_address());
2910 if (paddr1
!= paddr2
)
2911 return paddr1
< paddr2
;
2913 else if (seg2
->are_addresses_set())
2916 // A segment which holds large data comes after a segment which does
2917 // not hold large data.
2918 if (seg1
->is_large_data_segment())
2920 if (!seg2
->is_large_data_segment())
2923 else if (seg2
->is_large_data_segment())
2926 // Otherwise, we sort PT_LOAD segments based on the flags. Readonly
2927 // segments come before writable segments. Then writable segments
2928 // with data come before writable segments without data. Then
2929 // executable segments come before non-executable segments. Then
2930 // the unlikely case of a non-readable segment comes before the
2931 // normal case of a readable segment. If there are multiple
2932 // segments with the same type and flags, we require that the
2933 // address be set, and we sort by virtual address and then physical
2935 if ((flags1
& elfcpp::PF_W
) != (flags2
& elfcpp::PF_W
))
2936 return (flags1
& elfcpp::PF_W
) == 0;
2937 if ((flags1
& elfcpp::PF_W
) != 0
2938 && seg1
->has_any_data_sections() != seg2
->has_any_data_sections())
2939 return seg1
->has_any_data_sections();
2940 if ((flags1
& elfcpp::PF_X
) != (flags2
& elfcpp::PF_X
))
2941 return (flags1
& elfcpp::PF_X
) != 0;
2942 if ((flags1
& elfcpp::PF_R
) != (flags2
& elfcpp::PF_R
))
2943 return (flags1
& elfcpp::PF_R
) == 0;
2945 // We shouldn't get here--we shouldn't create segments which we
2946 // can't distinguish. Unless of course we are using a weird linker
2948 gold_assert(this->script_options_
->saw_phdrs_clause());
2952 // Increase OFF so that it is congruent to ADDR modulo ABI_PAGESIZE.
2955 align_file_offset(off_t off
, uint64_t addr
, uint64_t abi_pagesize
)
2957 uint64_t unsigned_off
= off
;
2958 uint64_t aligned_off
= ((unsigned_off
& ~(abi_pagesize
- 1))
2959 | (addr
& (abi_pagesize
- 1)));
2960 if (aligned_off
< unsigned_off
)
2961 aligned_off
+= abi_pagesize
;
2965 // Set the file offsets of all the segments, and all the sections they
2966 // contain. They have all been created. LOAD_SEG must be be laid out
2967 // first. Return the offset of the data to follow.
2970 Layout::set_segment_offsets(const Target
* target
, Output_segment
* load_seg
,
2971 unsigned int* pshndx
)
2973 // Sort them into the final order. We use a stable sort so that we
2974 // don't randomize the order of indistinguishable segments created
2975 // by linker scripts.
2976 std::stable_sort(this->segment_list_
.begin(), this->segment_list_
.end(),
2977 Layout::Compare_segments(this));
2979 // Find the PT_LOAD segments, and set their addresses and offsets
2980 // and their section's addresses and offsets.
2982 if (parameters
->options().user_set_Ttext())
2983 addr
= parameters
->options().Ttext();
2984 else if (parameters
->options().output_is_position_independent())
2987 addr
= target
->default_text_segment_address();
2990 // If LOAD_SEG is NULL, then the file header and segment headers
2991 // will not be loadable. But they still need to be at offset 0 in
2992 // the file. Set their offsets now.
2993 if (load_seg
== NULL
)
2995 for (Data_list::iterator p
= this->special_output_list_
.begin();
2996 p
!= this->special_output_list_
.end();
2999 off
= align_address(off
, (*p
)->addralign());
3000 (*p
)->set_address_and_file_offset(0, off
);
3001 off
+= (*p
)->data_size();
3005 unsigned int increase_relro
= this->increase_relro_
;
3006 if (this->script_options_
->saw_sections_clause())
3009 const bool check_sections
= parameters
->options().check_sections();
3010 Output_segment
* last_load_segment
= NULL
;
3012 for (Segment_list::iterator p
= this->segment_list_
.begin();
3013 p
!= this->segment_list_
.end();
3016 if ((*p
)->type() == elfcpp::PT_LOAD
)
3018 if (load_seg
!= NULL
&& load_seg
!= *p
)
3022 bool are_addresses_set
= (*p
)->are_addresses_set();
3023 if (are_addresses_set
)
3025 // When it comes to setting file offsets, we care about
3026 // the physical address.
3027 addr
= (*p
)->paddr();
3029 else if (parameters
->options().user_set_Tdata()
3030 && ((*p
)->flags() & elfcpp::PF_W
) != 0
3031 && (!parameters
->options().user_set_Tbss()
3032 || (*p
)->has_any_data_sections()))
3034 addr
= parameters
->options().Tdata();
3035 are_addresses_set
= true;
3037 else if (parameters
->options().user_set_Tbss()
3038 && ((*p
)->flags() & elfcpp::PF_W
) != 0
3039 && !(*p
)->has_any_data_sections())
3041 addr
= parameters
->options().Tbss();
3042 are_addresses_set
= true;
3045 uint64_t orig_addr
= addr
;
3046 uint64_t orig_off
= off
;
3048 uint64_t aligned_addr
= 0;
3049 uint64_t abi_pagesize
= target
->abi_pagesize();
3050 uint64_t common_pagesize
= target
->common_pagesize();
3052 if (!parameters
->options().nmagic()
3053 && !parameters
->options().omagic())
3054 (*p
)->set_minimum_p_align(common_pagesize
);
3056 if (!are_addresses_set
)
3058 // Skip the address forward one page, maintaining the same
3059 // position within the page. This lets us store both segments
3060 // overlapping on a single page in the file, but the loader will
3061 // put them on different pages in memory. We will revisit this
3062 // decision once we know the size of the segment.
3064 addr
= align_address(addr
, (*p
)->maximum_alignment());
3065 aligned_addr
= addr
;
3067 if ((addr
& (abi_pagesize
- 1)) != 0)
3068 addr
= addr
+ abi_pagesize
;
3070 off
= orig_off
+ ((addr
- orig_addr
) & (abi_pagesize
- 1));
3073 if (!parameters
->options().nmagic()
3074 && !parameters
->options().omagic())
3075 off
= align_file_offset(off
, addr
, abi_pagesize
);
3076 else if (load_seg
== NULL
)
3078 // This is -N or -n with a section script which prevents
3079 // us from using a load segment. We need to ensure that
3080 // the file offset is aligned to the alignment of the
3081 // segment. This is because the linker script
3082 // implicitly assumed a zero offset. If we don't align
3083 // here, then the alignment of the sections in the
3084 // linker script may not match the alignment of the
3085 // sections in the set_section_addresses call below,
3086 // causing an error about dot moving backward.
3087 off
= align_address(off
, (*p
)->maximum_alignment());
3090 unsigned int shndx_hold
= *pshndx
;
3091 bool has_relro
= false;
3092 uint64_t new_addr
= (*p
)->set_section_addresses(this, false, addr
,
3097 // Now that we know the size of this segment, we may be able
3098 // to save a page in memory, at the cost of wasting some
3099 // file space, by instead aligning to the start of a new
3100 // page. Here we use the real machine page size rather than
3101 // the ABI mandated page size. If the segment has been
3102 // aligned so that the relro data ends at a page boundary,
3103 // we do not try to realign it.
3105 if (!are_addresses_set
3107 && aligned_addr
!= addr
3108 && !parameters
->incremental())
3110 uint64_t first_off
= (common_pagesize
3112 & (common_pagesize
- 1)));
3113 uint64_t last_off
= new_addr
& (common_pagesize
- 1);
3116 && ((aligned_addr
& ~ (common_pagesize
- 1))
3117 != (new_addr
& ~ (common_pagesize
- 1)))
3118 && first_off
+ last_off
<= common_pagesize
)
3120 *pshndx
= shndx_hold
;
3121 addr
= align_address(aligned_addr
, common_pagesize
);
3122 addr
= align_address(addr
, (*p
)->maximum_alignment());
3123 off
= orig_off
+ ((addr
- orig_addr
) & (abi_pagesize
- 1));
3124 off
= align_file_offset(off
, addr
, abi_pagesize
);
3126 increase_relro
= this->increase_relro_
;
3127 if (this->script_options_
->saw_sections_clause())
3131 new_addr
= (*p
)->set_section_addresses(this, true, addr
,
3140 // Implement --check-sections. We know that the segments
3141 // are sorted by LMA.
3142 if (check_sections
&& last_load_segment
!= NULL
)
3144 gold_assert(last_load_segment
->paddr() <= (*p
)->paddr());
3145 if (last_load_segment
->paddr() + last_load_segment
->memsz()
3148 unsigned long long lb1
= last_load_segment
->paddr();
3149 unsigned long long le1
= lb1
+ last_load_segment
->memsz();
3150 unsigned long long lb2
= (*p
)->paddr();
3151 unsigned long long le2
= lb2
+ (*p
)->memsz();
3152 gold_error(_("load segment overlap [0x%llx -> 0x%llx] and "
3153 "[0x%llx -> 0x%llx]"),
3154 lb1
, le1
, lb2
, le2
);
3157 last_load_segment
= *p
;
3161 // Handle the non-PT_LOAD segments, setting their offsets from their
3162 // section's offsets.
3163 for (Segment_list::iterator p
= this->segment_list_
.begin();
3164 p
!= this->segment_list_
.end();
3167 if ((*p
)->type() != elfcpp::PT_LOAD
)
3168 (*p
)->set_offset((*p
)->type() == elfcpp::PT_GNU_RELRO
3173 // Set the TLS offsets for each section in the PT_TLS segment.
3174 if (this->tls_segment_
!= NULL
)
3175 this->tls_segment_
->set_tls_offsets();
3180 // Set the offsets of all the allocated sections when doing a
3181 // relocatable link. This does the same jobs as set_segment_offsets,
3182 // only for a relocatable link.
3185 Layout::set_relocatable_section_offsets(Output_data
* file_header
,
3186 unsigned int* pshndx
)
3190 file_header
->set_address_and_file_offset(0, 0);
3191 off
+= file_header
->data_size();
3193 for (Section_list::iterator p
= this->section_list_
.begin();
3194 p
!= this->section_list_
.end();
3197 // We skip unallocated sections here, except that group sections
3198 // have to come first.
3199 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) == 0
3200 && (*p
)->type() != elfcpp::SHT_GROUP
)
3203 off
= align_address(off
, (*p
)->addralign());
3205 // The linker script might have set the address.
3206 if (!(*p
)->is_address_valid())
3207 (*p
)->set_address(0);
3208 (*p
)->set_file_offset(off
);
3209 (*p
)->finalize_data_size();
3210 off
+= (*p
)->data_size();
3212 (*p
)->set_out_shndx(*pshndx
);
3219 // Set the file offset of all the sections not associated with a
3223 Layout::set_section_offsets(off_t off
, Layout::Section_offset_pass pass
)
3225 off_t startoff
= off
;
3228 for (Section_list::iterator p
= this->unattached_section_list_
.begin();
3229 p
!= this->unattached_section_list_
.end();
3232 // The symtab section is handled in create_symtab_sections.
3233 if (*p
== this->symtab_section_
)
3236 // If we've already set the data size, don't set it again.
3237 if ((*p
)->is_offset_valid() && (*p
)->is_data_size_valid())
3240 if (pass
== BEFORE_INPUT_SECTIONS_PASS
3241 && (*p
)->requires_postprocessing())
3243 (*p
)->create_postprocessing_buffer();
3244 this->any_postprocessing_sections_
= true;
3247 if (pass
== BEFORE_INPUT_SECTIONS_PASS
3248 && (*p
)->after_input_sections())
3250 else if (pass
== POSTPROCESSING_SECTIONS_PASS
3251 && (!(*p
)->after_input_sections()
3252 || (*p
)->type() == elfcpp::SHT_STRTAB
))
3254 else if (pass
== STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
3255 && (!(*p
)->after_input_sections()
3256 || (*p
)->type() != elfcpp::SHT_STRTAB
))
3259 if (!parameters
->incremental_update())
3261 off
= align_address(off
, (*p
)->addralign());
3262 (*p
)->set_file_offset(off
);
3263 (*p
)->finalize_data_size();
3267 // Incremental update: allocate file space from free list.
3268 (*p
)->pre_finalize_data_size();
3269 off_t current_size
= (*p
)->current_data_size();
3270 off
= this->allocate(current_size
, (*p
)->addralign(), startoff
);
3273 if (is_debugging_enabled(DEBUG_INCREMENTAL
))
3274 this->free_list_
.dump();
3275 gold_assert((*p
)->output_section() != NULL
);
3276 gold_fallback(_("out of patch space for section %s; "
3277 "relink with --incremental-full"),
3278 (*p
)->output_section()->name());
3280 (*p
)->set_file_offset(off
);
3281 (*p
)->finalize_data_size();
3282 if ((*p
)->data_size() > current_size
)
3284 gold_assert((*p
)->output_section() != NULL
);
3285 gold_fallback(_("%s: section changed size; "
3286 "relink with --incremental-full"),
3287 (*p
)->output_section()->name());
3289 gold_debug(DEBUG_INCREMENTAL
,
3290 "set_section_offsets: %08lx %08lx %s",
3291 static_cast<long>(off
),
3292 static_cast<long>((*p
)->data_size()),
3293 ((*p
)->output_section() != NULL
3294 ? (*p
)->output_section()->name() : "(special)"));
3297 off
+= (*p
)->data_size();
3301 // At this point the name must be set.
3302 if (pass
!= STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
)
3303 this->namepool_
.add((*p
)->name(), false, NULL
);
3308 // Set the section indexes of all the sections not associated with a
3312 Layout::set_section_indexes(unsigned int shndx
)
3314 for (Section_list::iterator p
= this->unattached_section_list_
.begin();
3315 p
!= this->unattached_section_list_
.end();
3318 if (!(*p
)->has_out_shndx())
3320 (*p
)->set_out_shndx(shndx
);
3327 // Set the section addresses according to the linker script. This is
3328 // only called when we see a SECTIONS clause. This returns the
3329 // program segment which should hold the file header and segment
3330 // headers, if any. It will return NULL if they should not be in a
3334 Layout::set_section_addresses_from_script(Symbol_table
* symtab
)
3336 Script_sections
* ss
= this->script_options_
->script_sections();
3337 gold_assert(ss
->saw_sections_clause());
3338 return this->script_options_
->set_section_addresses(symtab
, this);
3341 // Place the orphan sections in the linker script.
3344 Layout::place_orphan_sections_in_script()
3346 Script_sections
* ss
= this->script_options_
->script_sections();
3347 gold_assert(ss
->saw_sections_clause());
3349 // Place each orphaned output section in the script.
3350 for (Section_list::iterator p
= this->section_list_
.begin();
3351 p
!= this->section_list_
.end();
3354 if (!(*p
)->found_in_sections_clause())
3355 ss
->place_orphan(*p
);
3359 // Count the local symbols in the regular symbol table and the dynamic
3360 // symbol table, and build the respective string pools.
3363 Layout::count_local_symbols(const Task
* task
,
3364 const Input_objects
* input_objects
)
3366 // First, figure out an upper bound on the number of symbols we'll
3367 // be inserting into each pool. This helps us create the pools with
3368 // the right size, to avoid unnecessary hashtable resizing.
3369 unsigned int symbol_count
= 0;
3370 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
3371 p
!= input_objects
->relobj_end();
3373 symbol_count
+= (*p
)->local_symbol_count();
3375 // Go from "upper bound" to "estimate." We overcount for two
3376 // reasons: we double-count symbols that occur in more than one
3377 // object file, and we count symbols that are dropped from the
3378 // output. Add it all together and assume we overcount by 100%.
3381 // We assume all symbols will go into both the sympool and dynpool.
3382 this->sympool_
.reserve(symbol_count
);
3383 this->dynpool_
.reserve(symbol_count
);
3385 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
3386 p
!= input_objects
->relobj_end();
3389 Task_lock_obj
<Object
> tlo(task
, *p
);
3390 (*p
)->count_local_symbols(&this->sympool_
, &this->dynpool_
);
3394 // Create the symbol table sections. Here we also set the final
3395 // values of the symbols. At this point all the loadable sections are
3396 // fully laid out. SHNUM is the number of sections so far.
3399 Layout::create_symtab_sections(const Input_objects
* input_objects
,
3400 Symbol_table
* symtab
,
3406 if (parameters
->target().get_size() == 32)
3408 symsize
= elfcpp::Elf_sizes
<32>::sym_size
;
3411 else if (parameters
->target().get_size() == 64)
3413 symsize
= elfcpp::Elf_sizes
<64>::sym_size
;
3419 // Compute file offsets relative to the start of the symtab section.
3422 // Save space for the dummy symbol at the start of the section. We
3423 // never bother to write this out--it will just be left as zero.
3425 unsigned int local_symbol_index
= 1;
3427 // Add STT_SECTION symbols for each Output section which needs one.
3428 for (Section_list::iterator p
= this->section_list_
.begin();
3429 p
!= this->section_list_
.end();
3432 if (!(*p
)->needs_symtab_index())
3433 (*p
)->set_symtab_index(-1U);
3436 (*p
)->set_symtab_index(local_symbol_index
);
3437 ++local_symbol_index
;
3442 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
3443 p
!= input_objects
->relobj_end();
3446 unsigned int index
= (*p
)->finalize_local_symbols(local_symbol_index
,
3448 off
+= (index
- local_symbol_index
) * symsize
;
3449 local_symbol_index
= index
;
3452 unsigned int local_symcount
= local_symbol_index
;
3453 gold_assert(static_cast<off_t
>(local_symcount
* symsize
) == off
);
3456 size_t dyn_global_index
;
3458 if (this->dynsym_section_
== NULL
)
3461 dyn_global_index
= 0;
3466 dyn_global_index
= this->dynsym_section_
->info();
3467 off_t locsize
= dyn_global_index
* this->dynsym_section_
->entsize();
3468 dynoff
= this->dynsym_section_
->offset() + locsize
;
3469 dyncount
= (this->dynsym_section_
->data_size() - locsize
) / symsize
;
3470 gold_assert(static_cast<off_t
>(dyncount
* symsize
)
3471 == this->dynsym_section_
->data_size() - locsize
);
3474 off_t global_off
= off
;
3475 off
= symtab
->finalize(off
, dynoff
, dyn_global_index
, dyncount
,
3476 &this->sympool_
, &local_symcount
);
3478 if (!parameters
->options().strip_all())
3480 this->sympool_
.set_string_offsets();
3482 const char* symtab_name
= this->namepool_
.add(".symtab", false, NULL
);
3483 Output_section
* osymtab
= this->make_output_section(symtab_name
,
3487 this->symtab_section_
= osymtab
;
3489 Output_section_data
* pos
= new Output_data_fixed_space(off
, align
,
3491 osymtab
->add_output_section_data(pos
);
3493 // We generate a .symtab_shndx section if we have more than
3494 // SHN_LORESERVE sections. Technically it is possible that we
3495 // don't need one, because it is possible that there are no
3496 // symbols in any of sections with indexes larger than
3497 // SHN_LORESERVE. That is probably unusual, though, and it is
3498 // easier to always create one than to compute section indexes
3499 // twice (once here, once when writing out the symbols).
3500 if (shnum
>= elfcpp::SHN_LORESERVE
)
3502 const char* symtab_xindex_name
= this->namepool_
.add(".symtab_shndx",
3504 Output_section
* osymtab_xindex
=
3505 this->make_output_section(symtab_xindex_name
,
3506 elfcpp::SHT_SYMTAB_SHNDX
, 0,
3507 ORDER_INVALID
, false);
3509 size_t symcount
= off
/ symsize
;
3510 this->symtab_xindex_
= new Output_symtab_xindex(symcount
);
3512 osymtab_xindex
->add_output_section_data(this->symtab_xindex_
);
3514 osymtab_xindex
->set_link_section(osymtab
);
3515 osymtab_xindex
->set_addralign(4);
3516 osymtab_xindex
->set_entsize(4);
3518 osymtab_xindex
->set_after_input_sections();
3520 // This tells the driver code to wait until the symbol table
3521 // has written out before writing out the postprocessing
3522 // sections, including the .symtab_shndx section.
3523 this->any_postprocessing_sections_
= true;
3526 const char* strtab_name
= this->namepool_
.add(".strtab", false, NULL
);
3527 Output_section
* ostrtab
= this->make_output_section(strtab_name
,
3532 Output_section_data
* pstr
= new Output_data_strtab(&this->sympool_
);
3533 ostrtab
->add_output_section_data(pstr
);
3536 if (!parameters
->incremental_update())
3537 symtab_off
= align_address(*poff
, align
);
3540 symtab_off
= this->allocate(off
, align
, *poff
);
3542 gold_fallback(_("out of patch space for symbol table; "
3543 "relink with --incremental-full"));
3544 gold_debug(DEBUG_INCREMENTAL
,
3545 "create_symtab_sections: %08lx %08lx .symtab",
3546 static_cast<long>(symtab_off
),
3547 static_cast<long>(off
));
3550 symtab
->set_file_offset(symtab_off
+ global_off
);
3551 osymtab
->set_file_offset(symtab_off
);
3552 osymtab
->finalize_data_size();
3553 osymtab
->set_link_section(ostrtab
);
3554 osymtab
->set_info(local_symcount
);
3555 osymtab
->set_entsize(symsize
);
3557 if (symtab_off
+ off
> *poff
)
3558 *poff
= symtab_off
+ off
;
3562 // Create the .shstrtab section, which holds the names of the
3563 // sections. At the time this is called, we have created all the
3564 // output sections except .shstrtab itself.
3567 Layout::create_shstrtab()
3569 // FIXME: We don't need to create a .shstrtab section if we are
3570 // stripping everything.
3572 const char* name
= this->namepool_
.add(".shstrtab", false, NULL
);
3574 Output_section
* os
= this->make_output_section(name
, elfcpp::SHT_STRTAB
, 0,
3575 ORDER_INVALID
, false);
3577 if (strcmp(parameters
->options().compress_debug_sections(), "none") != 0)
3579 // We can't write out this section until we've set all the
3580 // section names, and we don't set the names of compressed
3581 // output sections until relocations are complete. FIXME: With
3582 // the current names we use, this is unnecessary.
3583 os
->set_after_input_sections();
3586 Output_section_data
* posd
= new Output_data_strtab(&this->namepool_
);
3587 os
->add_output_section_data(posd
);
3592 // Create the section headers. SIZE is 32 or 64. OFF is the file
3596 Layout::create_shdrs(const Output_section
* shstrtab_section
, off_t
* poff
)
3598 Output_section_headers
* oshdrs
;
3599 oshdrs
= new Output_section_headers(this,
3600 &this->segment_list_
,
3601 &this->section_list_
,
3602 &this->unattached_section_list_
,
3606 if (!parameters
->incremental_update())
3607 off
= align_address(*poff
, oshdrs
->addralign());
3610 oshdrs
->pre_finalize_data_size();
3611 off
= this->allocate(oshdrs
->data_size(), oshdrs
->addralign(), *poff
);
3613 gold_fallback(_("out of patch space for section header table; "
3614 "relink with --incremental-full"));
3615 gold_debug(DEBUG_INCREMENTAL
,
3616 "create_shdrs: %08lx %08lx (section header table)",
3617 static_cast<long>(off
),
3618 static_cast<long>(off
+ oshdrs
->data_size()));
3620 oshdrs
->set_address_and_file_offset(0, off
);
3621 off
+= oshdrs
->data_size();
3624 this->section_headers_
= oshdrs
;
3627 // Count the allocated sections.
3630 Layout::allocated_output_section_count() const
3632 size_t section_count
= 0;
3633 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
3634 p
!= this->segment_list_
.end();
3636 section_count
+= (*p
)->output_section_count();
3637 return section_count
;
3640 // Create the dynamic symbol table.
3643 Layout::create_dynamic_symtab(const Input_objects
* input_objects
,
3644 Symbol_table
* symtab
,
3645 Output_section
** pdynstr
,
3646 unsigned int* plocal_dynamic_count
,
3647 std::vector
<Symbol
*>* pdynamic_symbols
,
3648 Versions
* pversions
)
3650 // Count all the symbols in the dynamic symbol table, and set the
3651 // dynamic symbol indexes.
3653 // Skip symbol 0, which is always all zeroes.
3654 unsigned int index
= 1;
3656 // Add STT_SECTION symbols for each Output section which needs one.
3657 for (Section_list::iterator p
= this->section_list_
.begin();
3658 p
!= this->section_list_
.end();
3661 if (!(*p
)->needs_dynsym_index())
3662 (*p
)->set_dynsym_index(-1U);
3665 (*p
)->set_dynsym_index(index
);
3670 // Count the local symbols that need to go in the dynamic symbol table,
3671 // and set the dynamic symbol indexes.
3672 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
3673 p
!= input_objects
->relobj_end();
3676 unsigned int new_index
= (*p
)->set_local_dynsym_indexes(index
);
3680 unsigned int local_symcount
= index
;
3681 *plocal_dynamic_count
= local_symcount
;
3683 index
= symtab
->set_dynsym_indexes(index
, pdynamic_symbols
,
3684 &this->dynpool_
, pversions
);
3688 const int size
= parameters
->target().get_size();
3691 symsize
= elfcpp::Elf_sizes
<32>::sym_size
;
3694 else if (size
== 64)
3696 symsize
= elfcpp::Elf_sizes
<64>::sym_size
;
3702 // Create the dynamic symbol table section.
3704 Output_section
* dynsym
= this->choose_output_section(NULL
, ".dynsym",
3708 ORDER_DYNAMIC_LINKER
,
3711 Output_section_data
* odata
= new Output_data_fixed_space(index
* symsize
,
3714 dynsym
->add_output_section_data(odata
);
3716 dynsym
->set_info(local_symcount
);
3717 dynsym
->set_entsize(symsize
);
3718 dynsym
->set_addralign(align
);
3720 this->dynsym_section_
= dynsym
;
3722 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
3723 odyn
->add_section_address(elfcpp::DT_SYMTAB
, dynsym
);
3724 odyn
->add_constant(elfcpp::DT_SYMENT
, symsize
);
3726 // If there are more than SHN_LORESERVE allocated sections, we
3727 // create a .dynsym_shndx section. It is possible that we don't
3728 // need one, because it is possible that there are no dynamic
3729 // symbols in any of the sections with indexes larger than
3730 // SHN_LORESERVE. This is probably unusual, though, and at this
3731 // time we don't know the actual section indexes so it is
3732 // inconvenient to check.
3733 if (this->allocated_output_section_count() >= elfcpp::SHN_LORESERVE
)
3735 Output_section
* dynsym_xindex
=
3736 this->choose_output_section(NULL
, ".dynsym_shndx",
3737 elfcpp::SHT_SYMTAB_SHNDX
,
3739 false, ORDER_DYNAMIC_LINKER
, false);
3741 this->dynsym_xindex_
= new Output_symtab_xindex(index
);
3743 dynsym_xindex
->add_output_section_data(this->dynsym_xindex_
);
3745 dynsym_xindex
->set_link_section(dynsym
);
3746 dynsym_xindex
->set_addralign(4);
3747 dynsym_xindex
->set_entsize(4);
3749 dynsym_xindex
->set_after_input_sections();
3751 // This tells the driver code to wait until the symbol table has
3752 // written out before writing out the postprocessing sections,
3753 // including the .dynsym_shndx section.
3754 this->any_postprocessing_sections_
= true;
3757 // Create the dynamic string table section.
3759 Output_section
* dynstr
= this->choose_output_section(NULL
, ".dynstr",
3763 ORDER_DYNAMIC_LINKER
,
3766 Output_section_data
* strdata
= new Output_data_strtab(&this->dynpool_
);
3767 dynstr
->add_output_section_data(strdata
);
3769 dynsym
->set_link_section(dynstr
);
3770 this->dynamic_section_
->set_link_section(dynstr
);
3772 odyn
->add_section_address(elfcpp::DT_STRTAB
, dynstr
);
3773 odyn
->add_section_size(elfcpp::DT_STRSZ
, dynstr
);
3777 // Create the hash tables.
3779 if (strcmp(parameters
->options().hash_style(), "sysv") == 0
3780 || strcmp(parameters
->options().hash_style(), "both") == 0)
3782 unsigned char* phash
;
3783 unsigned int hashlen
;
3784 Dynobj::create_elf_hash_table(*pdynamic_symbols
, local_symcount
,
3787 Output_section
* hashsec
=
3788 this->choose_output_section(NULL
, ".hash", elfcpp::SHT_HASH
,
3789 elfcpp::SHF_ALLOC
, false,
3790 ORDER_DYNAMIC_LINKER
, false);
3792 Output_section_data
* hashdata
= new Output_data_const_buffer(phash
,
3796 hashsec
->add_output_section_data(hashdata
);
3798 hashsec
->set_link_section(dynsym
);
3799 hashsec
->set_entsize(4);
3801 odyn
->add_section_address(elfcpp::DT_HASH
, hashsec
);
3804 if (strcmp(parameters
->options().hash_style(), "gnu") == 0
3805 || strcmp(parameters
->options().hash_style(), "both") == 0)
3807 unsigned char* phash
;
3808 unsigned int hashlen
;
3809 Dynobj::create_gnu_hash_table(*pdynamic_symbols
, local_symcount
,
3812 Output_section
* hashsec
=
3813 this->choose_output_section(NULL
, ".gnu.hash", elfcpp::SHT_GNU_HASH
,
3814 elfcpp::SHF_ALLOC
, false,
3815 ORDER_DYNAMIC_LINKER
, false);
3817 Output_section_data
* hashdata
= new Output_data_const_buffer(phash
,
3821 hashsec
->add_output_section_data(hashdata
);
3823 hashsec
->set_link_section(dynsym
);
3825 // For a 64-bit target, the entries in .gnu.hash do not have a
3826 // uniform size, so we only set the entry size for a 32-bit
3828 if (parameters
->target().get_size() == 32)
3829 hashsec
->set_entsize(4);
3831 odyn
->add_section_address(elfcpp::DT_GNU_HASH
, hashsec
);
3835 // Assign offsets to each local portion of the dynamic symbol table.
3838 Layout::assign_local_dynsym_offsets(const Input_objects
* input_objects
)
3840 Output_section
* dynsym
= this->dynsym_section_
;
3841 gold_assert(dynsym
!= NULL
);
3843 off_t off
= dynsym
->offset();
3845 // Skip the dummy symbol at the start of the section.
3846 off
+= dynsym
->entsize();
3848 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
3849 p
!= input_objects
->relobj_end();
3852 unsigned int count
= (*p
)->set_local_dynsym_offset(off
);
3853 off
+= count
* dynsym
->entsize();
3857 // Create the version sections.
3860 Layout::create_version_sections(const Versions
* versions
,
3861 const Symbol_table
* symtab
,
3862 unsigned int local_symcount
,
3863 const std::vector
<Symbol
*>& dynamic_symbols
,
3864 const Output_section
* dynstr
)
3866 if (!versions
->any_defs() && !versions
->any_needs())
3869 switch (parameters
->size_and_endianness())
3871 #ifdef HAVE_TARGET_32_LITTLE
3872 case Parameters::TARGET_32_LITTLE
:
3873 this->sized_create_version_sections
<32, false>(versions
, symtab
,
3875 dynamic_symbols
, dynstr
);
3878 #ifdef HAVE_TARGET_32_BIG
3879 case Parameters::TARGET_32_BIG
:
3880 this->sized_create_version_sections
<32, true>(versions
, symtab
,
3882 dynamic_symbols
, dynstr
);
3885 #ifdef HAVE_TARGET_64_LITTLE
3886 case Parameters::TARGET_64_LITTLE
:
3887 this->sized_create_version_sections
<64, false>(versions
, symtab
,
3889 dynamic_symbols
, dynstr
);
3892 #ifdef HAVE_TARGET_64_BIG
3893 case Parameters::TARGET_64_BIG
:
3894 this->sized_create_version_sections
<64, true>(versions
, symtab
,
3896 dynamic_symbols
, dynstr
);
3904 // Create the version sections, sized version.
3906 template<int size
, bool big_endian
>
3908 Layout::sized_create_version_sections(
3909 const Versions
* versions
,
3910 const Symbol_table
* symtab
,
3911 unsigned int local_symcount
,
3912 const std::vector
<Symbol
*>& dynamic_symbols
,
3913 const Output_section
* dynstr
)
3915 Output_section
* vsec
= this->choose_output_section(NULL
, ".gnu.version",
3916 elfcpp::SHT_GNU_versym
,
3919 ORDER_DYNAMIC_LINKER
,
3922 unsigned char* vbuf
;
3924 versions
->symbol_section_contents
<size
, big_endian
>(symtab
, &this->dynpool_
,
3929 Output_section_data
* vdata
= new Output_data_const_buffer(vbuf
, vsize
, 2,
3932 vsec
->add_output_section_data(vdata
);
3933 vsec
->set_entsize(2);
3934 vsec
->set_link_section(this->dynsym_section_
);
3936 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
3937 odyn
->add_section_address(elfcpp::DT_VERSYM
, vsec
);
3939 if (versions
->any_defs())
3941 Output_section
* vdsec
;
3942 vdsec
= this->choose_output_section(NULL
, ".gnu.version_d",
3943 elfcpp::SHT_GNU_verdef
,
3945 false, ORDER_DYNAMIC_LINKER
, false);
3947 unsigned char* vdbuf
;
3948 unsigned int vdsize
;
3949 unsigned int vdentries
;
3950 versions
->def_section_contents
<size
, big_endian
>(&this->dynpool_
, &vdbuf
,
3951 &vdsize
, &vdentries
);
3953 Output_section_data
* vddata
=
3954 new Output_data_const_buffer(vdbuf
, vdsize
, 4, "** version defs");
3956 vdsec
->add_output_section_data(vddata
);
3957 vdsec
->set_link_section(dynstr
);
3958 vdsec
->set_info(vdentries
);
3960 odyn
->add_section_address(elfcpp::DT_VERDEF
, vdsec
);
3961 odyn
->add_constant(elfcpp::DT_VERDEFNUM
, vdentries
);
3964 if (versions
->any_needs())
3966 Output_section
* vnsec
;
3967 vnsec
= this->choose_output_section(NULL
, ".gnu.version_r",
3968 elfcpp::SHT_GNU_verneed
,
3970 false, ORDER_DYNAMIC_LINKER
, false);
3972 unsigned char* vnbuf
;
3973 unsigned int vnsize
;
3974 unsigned int vnentries
;
3975 versions
->need_section_contents
<size
, big_endian
>(&this->dynpool_
,
3979 Output_section_data
* vndata
=
3980 new Output_data_const_buffer(vnbuf
, vnsize
, 4, "** version refs");
3982 vnsec
->add_output_section_data(vndata
);
3983 vnsec
->set_link_section(dynstr
);
3984 vnsec
->set_info(vnentries
);
3986 odyn
->add_section_address(elfcpp::DT_VERNEED
, vnsec
);
3987 odyn
->add_constant(elfcpp::DT_VERNEEDNUM
, vnentries
);
3991 // Create the .interp section and PT_INTERP segment.
3994 Layout::create_interp(const Target
* target
)
3996 gold_assert(this->interp_segment_
== NULL
);
3998 const char* interp
= parameters
->options().dynamic_linker();
4001 interp
= target
->dynamic_linker();
4002 gold_assert(interp
!= NULL
);
4005 size_t len
= strlen(interp
) + 1;
4007 Output_section_data
* odata
= new Output_data_const(interp
, len
, 1);
4009 Output_section
* osec
= this->choose_output_section(NULL
, ".interp",
4010 elfcpp::SHT_PROGBITS
,
4012 false, ORDER_INTERP
,
4014 osec
->add_output_section_data(odata
);
4017 // Add dynamic tags for the PLT and the dynamic relocs. This is
4018 // called by the target-specific code. This does nothing if not doing
4021 // USE_REL is true for REL relocs rather than RELA relocs.
4023 // If PLT_GOT is not NULL, then DT_PLTGOT points to it.
4025 // If PLT_REL is not NULL, it is used for DT_PLTRELSZ, and DT_JMPREL,
4026 // and we also set DT_PLTREL. We use PLT_REL's output section, since
4027 // some targets have multiple reloc sections in PLT_REL.
4029 // If DYN_REL is not NULL, it is used for DT_REL/DT_RELA,
4030 // DT_RELSZ/DT_RELASZ, DT_RELENT/DT_RELAENT.
4032 // If ADD_DEBUG is true, we add a DT_DEBUG entry when generating an
4036 Layout::add_target_dynamic_tags(bool use_rel
, const Output_data
* plt_got
,
4037 const Output_data
* plt_rel
,
4038 const Output_data_reloc_generic
* dyn_rel
,
4039 bool add_debug
, bool dynrel_includes_plt
)
4041 Output_data_dynamic
* odyn
= this->dynamic_data_
;
4045 if (plt_got
!= NULL
&& plt_got
->output_section() != NULL
)
4046 odyn
->add_section_address(elfcpp::DT_PLTGOT
, plt_got
);
4048 if (plt_rel
!= NULL
&& plt_rel
->output_section() != NULL
)
4050 odyn
->add_section_size(elfcpp::DT_PLTRELSZ
, plt_rel
->output_section());
4051 odyn
->add_section_address(elfcpp::DT_JMPREL
, plt_rel
->output_section());
4052 odyn
->add_constant(elfcpp::DT_PLTREL
,
4053 use_rel
? elfcpp::DT_REL
: elfcpp::DT_RELA
);
4056 if (dyn_rel
!= NULL
&& dyn_rel
->output_section() != NULL
)
4058 odyn
->add_section_address(use_rel
? elfcpp::DT_REL
: elfcpp::DT_RELA
,
4060 if (plt_rel
!= NULL
&& dynrel_includes_plt
)
4061 odyn
->add_section_size(use_rel
? elfcpp::DT_RELSZ
: elfcpp::DT_RELASZ
,
4064 odyn
->add_section_size(use_rel
? elfcpp::DT_RELSZ
: elfcpp::DT_RELASZ
,
4066 const int size
= parameters
->target().get_size();
4071 rel_tag
= elfcpp::DT_RELENT
;
4073 rel_size
= Reloc_types
<elfcpp::SHT_REL
, 32, false>::reloc_size
;
4074 else if (size
== 64)
4075 rel_size
= Reloc_types
<elfcpp::SHT_REL
, 64, false>::reloc_size
;
4081 rel_tag
= elfcpp::DT_RELAENT
;
4083 rel_size
= Reloc_types
<elfcpp::SHT_RELA
, 32, false>::reloc_size
;
4084 else if (size
== 64)
4085 rel_size
= Reloc_types
<elfcpp::SHT_RELA
, 64, false>::reloc_size
;
4089 odyn
->add_constant(rel_tag
, rel_size
);
4091 if (parameters
->options().combreloc())
4093 size_t c
= dyn_rel
->relative_reloc_count();
4095 odyn
->add_constant((use_rel
4096 ? elfcpp::DT_RELCOUNT
4097 : elfcpp::DT_RELACOUNT
),
4102 if (add_debug
&& !parameters
->options().shared())
4104 // The value of the DT_DEBUG tag is filled in by the dynamic
4105 // linker at run time, and used by the debugger.
4106 odyn
->add_constant(elfcpp::DT_DEBUG
, 0);
4110 // Finish the .dynamic section and PT_DYNAMIC segment.
4113 Layout::finish_dynamic_section(const Input_objects
* input_objects
,
4114 const Symbol_table
* symtab
)
4116 if (!this->script_options_
->saw_phdrs_clause())
4118 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_DYNAMIC
,
4121 oseg
->add_output_section_to_nonload(this->dynamic_section_
,
4122 elfcpp::PF_R
| elfcpp::PF_W
);
4125 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
4127 for (Input_objects::Dynobj_iterator p
= input_objects
->dynobj_begin();
4128 p
!= input_objects
->dynobj_end();
4131 if (!(*p
)->is_needed() && (*p
)->as_needed())
4133 // This dynamic object was linked with --as-needed, but it
4138 odyn
->add_string(elfcpp::DT_NEEDED
, (*p
)->soname());
4141 if (parameters
->options().shared())
4143 const char* soname
= parameters
->options().soname();
4145 odyn
->add_string(elfcpp::DT_SONAME
, soname
);
4148 Symbol
* sym
= symtab
->lookup(parameters
->options().init());
4149 if (sym
!= NULL
&& sym
->is_defined() && !sym
->is_from_dynobj())
4150 odyn
->add_symbol(elfcpp::DT_INIT
, sym
);
4152 sym
= symtab
->lookup(parameters
->options().fini());
4153 if (sym
!= NULL
&& sym
->is_defined() && !sym
->is_from_dynobj())
4154 odyn
->add_symbol(elfcpp::DT_FINI
, sym
);
4156 // Look for .init_array, .preinit_array and .fini_array by checking
4158 for(Layout::Section_list::const_iterator p
= this->section_list_
.begin();
4159 p
!= this->section_list_
.end();
4161 switch((*p
)->type())
4163 case elfcpp::SHT_FINI_ARRAY
:
4164 odyn
->add_section_address(elfcpp::DT_FINI_ARRAY
, *p
);
4165 odyn
->add_section_size(elfcpp::DT_FINI_ARRAYSZ
, *p
);
4167 case elfcpp::SHT_INIT_ARRAY
:
4168 odyn
->add_section_address(elfcpp::DT_INIT_ARRAY
, *p
);
4169 odyn
->add_section_size(elfcpp::DT_INIT_ARRAYSZ
, *p
);
4171 case elfcpp::SHT_PREINIT_ARRAY
:
4172 odyn
->add_section_address(elfcpp::DT_PREINIT_ARRAY
, *p
);
4173 odyn
->add_section_size(elfcpp::DT_PREINIT_ARRAYSZ
, *p
);
4179 // Add a DT_RPATH entry if needed.
4180 const General_options::Dir_list
& rpath(parameters
->options().rpath());
4183 std::string rpath_val
;
4184 for (General_options::Dir_list::const_iterator p
= rpath
.begin();
4188 if (rpath_val
.empty())
4189 rpath_val
= p
->name();
4192 // Eliminate duplicates.
4193 General_options::Dir_list::const_iterator q
;
4194 for (q
= rpath
.begin(); q
!= p
; ++q
)
4195 if (q
->name() == p
->name())
4200 rpath_val
+= p
->name();
4205 odyn
->add_string(elfcpp::DT_RPATH
, rpath_val
);
4206 if (parameters
->options().enable_new_dtags())
4207 odyn
->add_string(elfcpp::DT_RUNPATH
, rpath_val
);
4210 // Look for text segments that have dynamic relocations.
4211 bool have_textrel
= false;
4212 if (!this->script_options_
->saw_sections_clause())
4214 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
4215 p
!= this->segment_list_
.end();
4218 if ((*p
)->type() == elfcpp::PT_LOAD
4219 && ((*p
)->flags() & elfcpp::PF_W
) == 0
4220 && (*p
)->has_dynamic_reloc())
4222 have_textrel
= true;
4229 // We don't know the section -> segment mapping, so we are
4230 // conservative and just look for readonly sections with
4231 // relocations. If those sections wind up in writable segments,
4232 // then we have created an unnecessary DT_TEXTREL entry.
4233 for (Section_list::const_iterator p
= this->section_list_
.begin();
4234 p
!= this->section_list_
.end();
4237 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) != 0
4238 && ((*p
)->flags() & elfcpp::SHF_WRITE
) == 0
4239 && (*p
)->has_dynamic_reloc())
4241 have_textrel
= true;
4247 if (parameters
->options().filter() != NULL
)
4248 odyn
->add_string(elfcpp::DT_FILTER
, parameters
->options().filter());
4249 if (parameters
->options().any_auxiliary())
4251 for (options::String_set::const_iterator p
=
4252 parameters
->options().auxiliary_begin();
4253 p
!= parameters
->options().auxiliary_end();
4255 odyn
->add_string(elfcpp::DT_AUXILIARY
, *p
);
4258 // Add a DT_FLAGS entry if necessary.
4259 unsigned int flags
= 0;
4262 // Add a DT_TEXTREL for compatibility with older loaders.
4263 odyn
->add_constant(elfcpp::DT_TEXTREL
, 0);
4264 flags
|= elfcpp::DF_TEXTREL
;
4266 if (parameters
->options().text())
4267 gold_error(_("read-only segment has dynamic relocations"));
4268 else if (parameters
->options().warn_shared_textrel()
4269 && parameters
->options().shared())
4270 gold_warning(_("shared library text segment is not shareable"));
4272 if (parameters
->options().shared() && this->has_static_tls())
4273 flags
|= elfcpp::DF_STATIC_TLS
;
4274 if (parameters
->options().origin())
4275 flags
|= elfcpp::DF_ORIGIN
;
4276 if (parameters
->options().Bsymbolic())
4278 flags
|= elfcpp::DF_SYMBOLIC
;
4279 // Add DT_SYMBOLIC for compatibility with older loaders.
4280 odyn
->add_constant(elfcpp::DT_SYMBOLIC
, 0);
4282 if (parameters
->options().now())
4283 flags
|= elfcpp::DF_BIND_NOW
;
4285 odyn
->add_constant(elfcpp::DT_FLAGS
, flags
);
4288 if (parameters
->options().initfirst())
4289 flags
|= elfcpp::DF_1_INITFIRST
;
4290 if (parameters
->options().interpose())
4291 flags
|= elfcpp::DF_1_INTERPOSE
;
4292 if (parameters
->options().loadfltr())
4293 flags
|= elfcpp::DF_1_LOADFLTR
;
4294 if (parameters
->options().nodefaultlib())
4295 flags
|= elfcpp::DF_1_NODEFLIB
;
4296 if (parameters
->options().nodelete())
4297 flags
|= elfcpp::DF_1_NODELETE
;
4298 if (parameters
->options().nodlopen())
4299 flags
|= elfcpp::DF_1_NOOPEN
;
4300 if (parameters
->options().nodump())
4301 flags
|= elfcpp::DF_1_NODUMP
;
4302 if (!parameters
->options().shared())
4303 flags
&= ~(elfcpp::DF_1_INITFIRST
4304 | elfcpp::DF_1_NODELETE
4305 | elfcpp::DF_1_NOOPEN
);
4306 if (parameters
->options().origin())
4307 flags
|= elfcpp::DF_1_ORIGIN
;
4308 if (parameters
->options().now())
4309 flags
|= elfcpp::DF_1_NOW
;
4311 odyn
->add_constant(elfcpp::DT_FLAGS_1
, flags
);
4314 // Set the size of the _DYNAMIC symbol table to be the size of the
4318 Layout::set_dynamic_symbol_size(const Symbol_table
* symtab
)
4320 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
4321 odyn
->finalize_data_size();
4322 off_t data_size
= odyn
->data_size();
4323 const int size
= parameters
->target().get_size();
4325 symtab
->get_sized_symbol
<32>(this->dynamic_symbol_
)->set_symsize(data_size
);
4326 else if (size
== 64)
4327 symtab
->get_sized_symbol
<64>(this->dynamic_symbol_
)->set_symsize(data_size
);
4332 // The mapping of input section name prefixes to output section names.
4333 // In some cases one prefix is itself a prefix of another prefix; in
4334 // such a case the longer prefix must come first. These prefixes are
4335 // based on the GNU linker default ELF linker script.
4337 #define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 }
4338 const Layout::Section_name_mapping
Layout::section_name_mapping
[] =
4340 MAPPING_INIT(".text.", ".text"),
4341 MAPPING_INIT(".rodata.", ".rodata"),
4342 MAPPING_INIT(".data.rel.ro.local", ".data.rel.ro.local"),
4343 MAPPING_INIT(".data.rel.ro", ".data.rel.ro"),
4344 MAPPING_INIT(".data.", ".data"),
4345 MAPPING_INIT(".bss.", ".bss"),
4346 MAPPING_INIT(".tdata.", ".tdata"),
4347 MAPPING_INIT(".tbss.", ".tbss"),
4348 MAPPING_INIT(".init_array.", ".init_array"),
4349 MAPPING_INIT(".fini_array.", ".fini_array"),
4350 MAPPING_INIT(".sdata.", ".sdata"),
4351 MAPPING_INIT(".sbss.", ".sbss"),
4352 // FIXME: In the GNU linker, .sbss2 and .sdata2 are handled
4353 // differently depending on whether it is creating a shared library.
4354 MAPPING_INIT(".sdata2.", ".sdata"),
4355 MAPPING_INIT(".sbss2.", ".sbss"),
4356 MAPPING_INIT(".lrodata.", ".lrodata"),
4357 MAPPING_INIT(".ldata.", ".ldata"),
4358 MAPPING_INIT(".lbss.", ".lbss"),
4359 MAPPING_INIT(".gcc_except_table.", ".gcc_except_table"),
4360 MAPPING_INIT(".gnu.linkonce.d.rel.ro.local.", ".data.rel.ro.local"),
4361 MAPPING_INIT(".gnu.linkonce.d.rel.ro.", ".data.rel.ro"),
4362 MAPPING_INIT(".gnu.linkonce.t.", ".text"),
4363 MAPPING_INIT(".gnu.linkonce.r.", ".rodata"),
4364 MAPPING_INIT(".gnu.linkonce.d.", ".data"),
4365 MAPPING_INIT(".gnu.linkonce.b.", ".bss"),
4366 MAPPING_INIT(".gnu.linkonce.s.", ".sdata"),
4367 MAPPING_INIT(".gnu.linkonce.sb.", ".sbss"),
4368 MAPPING_INIT(".gnu.linkonce.s2.", ".sdata"),
4369 MAPPING_INIT(".gnu.linkonce.sb2.", ".sbss"),
4370 MAPPING_INIT(".gnu.linkonce.wi.", ".debug_info"),
4371 MAPPING_INIT(".gnu.linkonce.td.", ".tdata"),
4372 MAPPING_INIT(".gnu.linkonce.tb.", ".tbss"),
4373 MAPPING_INIT(".gnu.linkonce.lr.", ".lrodata"),
4374 MAPPING_INIT(".gnu.linkonce.l.", ".ldata"),
4375 MAPPING_INIT(".gnu.linkonce.lb.", ".lbss"),
4376 MAPPING_INIT(".ARM.extab", ".ARM.extab"),
4377 MAPPING_INIT(".gnu.linkonce.armextab.", ".ARM.extab"),
4378 MAPPING_INIT(".ARM.exidx", ".ARM.exidx"),
4379 MAPPING_INIT(".gnu.linkonce.armexidx.", ".ARM.exidx"),
4383 const int Layout::section_name_mapping_count
=
4384 (sizeof(Layout::section_name_mapping
)
4385 / sizeof(Layout::section_name_mapping
[0]));
4387 // Choose the output section name to use given an input section name.
4388 // Set *PLEN to the length of the name. *PLEN is initialized to the
4392 Layout::output_section_name(const Relobj
* relobj
, const char* name
,
4395 // gcc 4.3 generates the following sorts of section names when it
4396 // needs a section name specific to a function:
4402 // .data.rel.local.FN
4404 // .data.rel.ro.local.FN
4411 // The GNU linker maps all of those to the part before the .FN,
4412 // except that .data.rel.local.FN is mapped to .data, and
4413 // .data.rel.ro.local.FN is mapped to .data.rel.ro. The sections
4414 // beginning with .data.rel.ro.local are grouped together.
4416 // For an anonymous namespace, the string FN can contain a '.'.
4418 // Also of interest: .rodata.strN.N, .rodata.cstN, both of which the
4419 // GNU linker maps to .rodata.
4421 // The .data.rel.ro sections are used with -z relro. The sections
4422 // are recognized by name. We use the same names that the GNU
4423 // linker does for these sections.
4425 // It is hard to handle this in a principled way, so we don't even
4426 // try. We use a table of mappings. If the input section name is
4427 // not found in the table, we simply use it as the output section
4430 const Section_name_mapping
* psnm
= section_name_mapping
;
4431 for (int i
= 0; i
< section_name_mapping_count
; ++i
, ++psnm
)
4433 if (strncmp(name
, psnm
->from
, psnm
->fromlen
) == 0)
4435 *plen
= psnm
->tolen
;
4440 // As an additional complication, .ctors sections are output in
4441 // either .ctors or .init_array sections, and .dtors sections are
4442 // output in either .dtors or .fini_array sections.
4443 if (is_prefix_of(".ctors.", name
) || is_prefix_of(".dtors.", name
))
4445 if (parameters
->options().ctors_in_init_array())
4448 return name
[1] == 'c' ? ".init_array" : ".fini_array";
4453 return name
[1] == 'c' ? ".ctors" : ".dtors";
4456 if (parameters
->options().ctors_in_init_array()
4457 && (strcmp(name
, ".ctors") == 0 || strcmp(name
, ".dtors") == 0))
4459 // To make .init_array/.fini_array work with gcc we must exclude
4460 // .ctors and .dtors sections from the crtbegin and crtend
4463 || (!Layout::match_file_name(relobj
, "crtbegin")
4464 && !Layout::match_file_name(relobj
, "crtend")))
4467 return name
[1] == 'c' ? ".init_array" : ".fini_array";
4474 // Return true if RELOBJ is an input file whose base name matches
4475 // FILE_NAME. The base name must have an extension of ".o", and must
4476 // be exactly FILE_NAME.o or FILE_NAME, one character, ".o". This is
4477 // to match crtbegin.o as well as crtbeginS.o without getting confused
4478 // by other possibilities. Overall matching the file name this way is
4479 // a dreadful hack, but the GNU linker does it in order to better
4480 // support gcc, and we need to be compatible.
4483 Layout::match_file_name(const Relobj
* relobj
, const char* match
)
4485 const std::string
& file_name(relobj
->name());
4486 const char* base_name
= lbasename(file_name
.c_str());
4487 size_t match_len
= strlen(match
);
4488 if (strncmp(base_name
, match
, match_len
) != 0)
4490 size_t base_len
= strlen(base_name
);
4491 if (base_len
!= match_len
+ 2 && base_len
!= match_len
+ 3)
4493 return memcmp(base_name
+ base_len
- 2, ".o", 2) == 0;
4496 // Check if a comdat group or .gnu.linkonce section with the given
4497 // NAME is selected for the link. If there is already a section,
4498 // *KEPT_SECTION is set to point to the existing section and the
4499 // function returns false. Otherwise, OBJECT, SHNDX, IS_COMDAT, and
4500 // IS_GROUP_NAME are recorded for this NAME in the layout object,
4501 // *KEPT_SECTION is set to the internal copy and the function returns
4505 Layout::find_or_add_kept_section(const std::string
& name
,
4510 Kept_section
** kept_section
)
4512 // It's normal to see a couple of entries here, for the x86 thunk
4513 // sections. If we see more than a few, we're linking a C++
4514 // program, and we resize to get more space to minimize rehashing.
4515 if (this->signatures_
.size() > 4
4516 && !this->resized_signatures_
)
4518 reserve_unordered_map(&this->signatures_
,
4519 this->number_of_input_files_
* 64);
4520 this->resized_signatures_
= true;
4523 Kept_section candidate
;
4524 std::pair
<Signatures::iterator
, bool> ins
=
4525 this->signatures_
.insert(std::make_pair(name
, candidate
));
4527 if (kept_section
!= NULL
)
4528 *kept_section
= &ins
.first
->second
;
4531 // This is the first time we've seen this signature.
4532 ins
.first
->second
.set_object(object
);
4533 ins
.first
->second
.set_shndx(shndx
);
4535 ins
.first
->second
.set_is_comdat();
4537 ins
.first
->second
.set_is_group_name();
4541 // We have already seen this signature.
4543 if (ins
.first
->second
.is_group_name())
4545 // We've already seen a real section group with this signature.
4546 // If the kept group is from a plugin object, and we're in the
4547 // replacement phase, accept the new one as a replacement.
4548 if (ins
.first
->second
.object() == NULL
4549 && parameters
->options().plugins()->in_replacement_phase())
4551 ins
.first
->second
.set_object(object
);
4552 ins
.first
->second
.set_shndx(shndx
);
4557 else if (is_group_name
)
4559 // This is a real section group, and we've already seen a
4560 // linkonce section with this signature. Record that we've seen
4561 // a section group, and don't include this section group.
4562 ins
.first
->second
.set_is_group_name();
4567 // We've already seen a linkonce section and this is a linkonce
4568 // section. These don't block each other--this may be the same
4569 // symbol name with different section types.
4574 // Store the allocated sections into the section list.
4577 Layout::get_allocated_sections(Section_list
* section_list
) const
4579 for (Section_list::const_iterator p
= this->section_list_
.begin();
4580 p
!= this->section_list_
.end();
4582 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) != 0)
4583 section_list
->push_back(*p
);
4586 // Create an output segment.
4589 Layout::make_output_segment(elfcpp::Elf_Word type
, elfcpp::Elf_Word flags
)
4591 gold_assert(!parameters
->options().relocatable());
4592 Output_segment
* oseg
= new Output_segment(type
, flags
);
4593 this->segment_list_
.push_back(oseg
);
4595 if (type
== elfcpp::PT_TLS
)
4596 this->tls_segment_
= oseg
;
4597 else if (type
== elfcpp::PT_GNU_RELRO
)
4598 this->relro_segment_
= oseg
;
4599 else if (type
== elfcpp::PT_INTERP
)
4600 this->interp_segment_
= oseg
;
4605 // Return the file offset of the normal symbol table.
4608 Layout::symtab_section_offset() const
4610 if (this->symtab_section_
!= NULL
)
4611 return this->symtab_section_
->offset();
4615 // Return the section index of the normal symbol table. It may have
4616 // been stripped by the -s/--strip-all option.
4619 Layout::symtab_section_shndx() const
4621 if (this->symtab_section_
!= NULL
)
4622 return this->symtab_section_
->out_shndx();
4626 // Write out the Output_sections. Most won't have anything to write,
4627 // since most of the data will come from input sections which are
4628 // handled elsewhere. But some Output_sections do have Output_data.
4631 Layout::write_output_sections(Output_file
* of
) const
4633 for (Section_list::const_iterator p
= this->section_list_
.begin();
4634 p
!= this->section_list_
.end();
4637 if (!(*p
)->after_input_sections())
4642 // Write out data not associated with a section or the symbol table.
4645 Layout::write_data(const Symbol_table
* symtab
, Output_file
* of
) const
4647 if (!parameters
->options().strip_all())
4649 const Output_section
* symtab_section
= this->symtab_section_
;
4650 for (Section_list::const_iterator p
= this->section_list_
.begin();
4651 p
!= this->section_list_
.end();
4654 if ((*p
)->needs_symtab_index())
4656 gold_assert(symtab_section
!= NULL
);
4657 unsigned int index
= (*p
)->symtab_index();
4658 gold_assert(index
> 0 && index
!= -1U);
4659 off_t off
= (symtab_section
->offset()
4660 + index
* symtab_section
->entsize());
4661 symtab
->write_section_symbol(*p
, this->symtab_xindex_
, of
, off
);
4666 const Output_section
* dynsym_section
= this->dynsym_section_
;
4667 for (Section_list::const_iterator p
= this->section_list_
.begin();
4668 p
!= this->section_list_
.end();
4671 if ((*p
)->needs_dynsym_index())
4673 gold_assert(dynsym_section
!= NULL
);
4674 unsigned int index
= (*p
)->dynsym_index();
4675 gold_assert(index
> 0 && index
!= -1U);
4676 off_t off
= (dynsym_section
->offset()
4677 + index
* dynsym_section
->entsize());
4678 symtab
->write_section_symbol(*p
, this->dynsym_xindex_
, of
, off
);
4682 // Write out the Output_data which are not in an Output_section.
4683 for (Data_list::const_iterator p
= this->special_output_list_
.begin();
4684 p
!= this->special_output_list_
.end();
4689 // Write out the Output_sections which can only be written after the
4690 // input sections are complete.
4693 Layout::write_sections_after_input_sections(Output_file
* of
)
4695 // Determine the final section offsets, and thus the final output
4696 // file size. Note we finalize the .shstrab last, to allow the
4697 // after_input_section sections to modify their section-names before
4699 if (this->any_postprocessing_sections_
)
4701 off_t off
= this->output_file_size_
;
4702 off
= this->set_section_offsets(off
, POSTPROCESSING_SECTIONS_PASS
);
4704 // Now that we've finalized the names, we can finalize the shstrab.
4706 this->set_section_offsets(off
,
4707 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
);
4709 if (off
> this->output_file_size_
)
4712 this->output_file_size_
= off
;
4716 for (Section_list::const_iterator p
= this->section_list_
.begin();
4717 p
!= this->section_list_
.end();
4720 if ((*p
)->after_input_sections())
4724 this->section_headers_
->write(of
);
4727 // If the build ID requires computing a checksum, do so here, and
4728 // write it out. We compute a checksum over the entire file because
4729 // that is simplest.
4732 Layout::write_build_id(Output_file
* of
) const
4734 if (this->build_id_note_
== NULL
)
4737 const unsigned char* iv
= of
->get_input_view(0, this->output_file_size_
);
4739 unsigned char* ov
= of
->get_output_view(this->build_id_note_
->offset(),
4740 this->build_id_note_
->data_size());
4742 const char* style
= parameters
->options().build_id();
4743 if (strcmp(style
, "sha1") == 0)
4746 sha1_init_ctx(&ctx
);
4747 sha1_process_bytes(iv
, this->output_file_size_
, &ctx
);
4748 sha1_finish_ctx(&ctx
, ov
);
4750 else if (strcmp(style
, "md5") == 0)
4754 md5_process_bytes(iv
, this->output_file_size_
, &ctx
);
4755 md5_finish_ctx(&ctx
, ov
);
4760 of
->write_output_view(this->build_id_note_
->offset(),
4761 this->build_id_note_
->data_size(),
4764 of
->free_input_view(0, this->output_file_size_
, iv
);
4767 // Write out a binary file. This is called after the link is
4768 // complete. IN is the temporary output file we used to generate the
4769 // ELF code. We simply walk through the segments, read them from
4770 // their file offset in IN, and write them to their load address in
4771 // the output file. FIXME: with a bit more work, we could support
4772 // S-records and/or Intel hex format here.
4775 Layout::write_binary(Output_file
* in
) const
4777 gold_assert(parameters
->options().oformat_enum()
4778 == General_options::OBJECT_FORMAT_BINARY
);
4780 // Get the size of the binary file.
4781 uint64_t max_load_address
= 0;
4782 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
4783 p
!= this->segment_list_
.end();
4786 if ((*p
)->type() == elfcpp::PT_LOAD
&& (*p
)->filesz() > 0)
4788 uint64_t max_paddr
= (*p
)->paddr() + (*p
)->filesz();
4789 if (max_paddr
> max_load_address
)
4790 max_load_address
= max_paddr
;
4794 Output_file
out(parameters
->options().output_file_name());
4795 out
.open(max_load_address
);
4797 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
4798 p
!= this->segment_list_
.end();
4801 if ((*p
)->type() == elfcpp::PT_LOAD
&& (*p
)->filesz() > 0)
4803 const unsigned char* vin
= in
->get_input_view((*p
)->offset(),
4805 unsigned char* vout
= out
.get_output_view((*p
)->paddr(),
4807 memcpy(vout
, vin
, (*p
)->filesz());
4808 out
.write_output_view((*p
)->paddr(), (*p
)->filesz(), vout
);
4809 in
->free_input_view((*p
)->offset(), (*p
)->filesz(), vin
);
4816 // Print the output sections to the map file.
4819 Layout::print_to_mapfile(Mapfile
* mapfile
) const
4821 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
4822 p
!= this->segment_list_
.end();
4824 (*p
)->print_sections_to_mapfile(mapfile
);
4827 // Print statistical information to stderr. This is used for --stats.
4830 Layout::print_stats() const
4832 this->namepool_
.print_stats("section name pool");
4833 this->sympool_
.print_stats("output symbol name pool");
4834 this->dynpool_
.print_stats("dynamic name pool");
4836 for (Section_list::const_iterator p
= this->section_list_
.begin();
4837 p
!= this->section_list_
.end();
4839 (*p
)->print_merge_stats();
4842 // Write_sections_task methods.
4844 // We can always run this task.
4847 Write_sections_task::is_runnable()
4852 // We need to unlock both OUTPUT_SECTIONS_BLOCKER and FINAL_BLOCKER
4856 Write_sections_task::locks(Task_locker
* tl
)
4858 tl
->add(this, this->output_sections_blocker_
);
4859 tl
->add(this, this->final_blocker_
);
4862 // Run the task--write out the data.
4865 Write_sections_task::run(Workqueue
*)
4867 this->layout_
->write_output_sections(this->of_
);
4870 // Write_data_task methods.
4872 // We can always run this task.
4875 Write_data_task::is_runnable()
4880 // We need to unlock FINAL_BLOCKER when finished.
4883 Write_data_task::locks(Task_locker
* tl
)
4885 tl
->add(this, this->final_blocker_
);
4888 // Run the task--write out the data.
4891 Write_data_task::run(Workqueue
*)
4893 this->layout_
->write_data(this->symtab_
, this->of_
);
4896 // Write_symbols_task methods.
4898 // We can always run this task.
4901 Write_symbols_task::is_runnable()
4906 // We need to unlock FINAL_BLOCKER when finished.
4909 Write_symbols_task::locks(Task_locker
* tl
)
4911 tl
->add(this, this->final_blocker_
);
4914 // Run the task--write out the symbols.
4917 Write_symbols_task::run(Workqueue
*)
4919 this->symtab_
->write_globals(this->sympool_
, this->dynpool_
,
4920 this->layout_
->symtab_xindex(),
4921 this->layout_
->dynsym_xindex(), this->of_
);
4924 // Write_after_input_sections_task methods.
4926 // We can only run this task after the input sections have completed.
4929 Write_after_input_sections_task::is_runnable()
4931 if (this->input_sections_blocker_
->is_blocked())
4932 return this->input_sections_blocker_
;
4936 // We need to unlock FINAL_BLOCKER when finished.
4939 Write_after_input_sections_task::locks(Task_locker
* tl
)
4941 tl
->add(this, this->final_blocker_
);
4947 Write_after_input_sections_task::run(Workqueue
*)
4949 this->layout_
->write_sections_after_input_sections(this->of_
);
4952 // Close_task_runner methods.
4954 // Run the task--close the file.
4957 Close_task_runner::run(Workqueue
*, const Task
*)
4959 // If we need to compute a checksum for the BUILD if, we do so here.
4960 this->layout_
->write_build_id(this->of_
);
4962 // If we've been asked to create a binary file, we do so here.
4963 if (this->options_
->oformat_enum() != General_options::OBJECT_FORMAT_ELF
)
4964 this->layout_
->write_binary(this->of_
);
4969 // Instantiate the templates we need. We could use the configure
4970 // script to restrict this to only the ones for implemented targets.
4972 #ifdef HAVE_TARGET_32_LITTLE
4975 Layout::init_fixed_output_section
<32, false>(
4977 elfcpp::Shdr
<32, false>& shdr
);
4980 #ifdef HAVE_TARGET_32_BIG
4983 Layout::init_fixed_output_section
<32, true>(
4985 elfcpp::Shdr
<32, true>& shdr
);
4988 #ifdef HAVE_TARGET_64_LITTLE
4991 Layout::init_fixed_output_section
<64, false>(
4993 elfcpp::Shdr
<64, false>& shdr
);
4996 #ifdef HAVE_TARGET_64_BIG
4999 Layout::init_fixed_output_section
<64, true>(
5001 elfcpp::Shdr
<64, true>& shdr
);
5004 #ifdef HAVE_TARGET_32_LITTLE
5007 Layout::layout
<32, false>(Sized_relobj_file
<32, false>* object
,
5010 const elfcpp::Shdr
<32, false>& shdr
,
5011 unsigned int, unsigned int, off_t
*);
5014 #ifdef HAVE_TARGET_32_BIG
5017 Layout::layout
<32, true>(Sized_relobj_file
<32, true>* object
,
5020 const elfcpp::Shdr
<32, true>& shdr
,
5021 unsigned int, unsigned int, off_t
*);
5024 #ifdef HAVE_TARGET_64_LITTLE
5027 Layout::layout
<64, false>(Sized_relobj_file
<64, false>* object
,
5030 const elfcpp::Shdr
<64, false>& shdr
,
5031 unsigned int, unsigned int, off_t
*);
5034 #ifdef HAVE_TARGET_64_BIG
5037 Layout::layout
<64, true>(Sized_relobj_file
<64, true>* object
,
5040 const elfcpp::Shdr
<64, true>& shdr
,
5041 unsigned int, unsigned int, off_t
*);
5044 #ifdef HAVE_TARGET_32_LITTLE
5047 Layout::layout_reloc
<32, false>(Sized_relobj_file
<32, false>* object
,
5048 unsigned int reloc_shndx
,
5049 const elfcpp::Shdr
<32, false>& shdr
,
5050 Output_section
* data_section
,
5051 Relocatable_relocs
* rr
);
5054 #ifdef HAVE_TARGET_32_BIG
5057 Layout::layout_reloc
<32, true>(Sized_relobj_file
<32, true>* object
,
5058 unsigned int reloc_shndx
,
5059 const elfcpp::Shdr
<32, true>& shdr
,
5060 Output_section
* data_section
,
5061 Relocatable_relocs
* rr
);
5064 #ifdef HAVE_TARGET_64_LITTLE
5067 Layout::layout_reloc
<64, false>(Sized_relobj_file
<64, false>* object
,
5068 unsigned int reloc_shndx
,
5069 const elfcpp::Shdr
<64, false>& shdr
,
5070 Output_section
* data_section
,
5071 Relocatable_relocs
* rr
);
5074 #ifdef HAVE_TARGET_64_BIG
5077 Layout::layout_reloc
<64, true>(Sized_relobj_file
<64, true>* object
,
5078 unsigned int reloc_shndx
,
5079 const elfcpp::Shdr
<64, true>& shdr
,
5080 Output_section
* data_section
,
5081 Relocatable_relocs
* rr
);
5084 #ifdef HAVE_TARGET_32_LITTLE
5087 Layout::layout_group
<32, false>(Symbol_table
* symtab
,
5088 Sized_relobj_file
<32, false>* object
,
5090 const char* group_section_name
,
5091 const char* signature
,
5092 const elfcpp::Shdr
<32, false>& shdr
,
5093 elfcpp::Elf_Word flags
,
5094 std::vector
<unsigned int>* shndxes
);
5097 #ifdef HAVE_TARGET_32_BIG
5100 Layout::layout_group
<32, true>(Symbol_table
* symtab
,
5101 Sized_relobj_file
<32, true>* object
,
5103 const char* group_section_name
,
5104 const char* signature
,
5105 const elfcpp::Shdr
<32, true>& shdr
,
5106 elfcpp::Elf_Word flags
,
5107 std::vector
<unsigned int>* shndxes
);
5110 #ifdef HAVE_TARGET_64_LITTLE
5113 Layout::layout_group
<64, false>(Symbol_table
* symtab
,
5114 Sized_relobj_file
<64, false>* object
,
5116 const char* group_section_name
,
5117 const char* signature
,
5118 const elfcpp::Shdr
<64, false>& shdr
,
5119 elfcpp::Elf_Word flags
,
5120 std::vector
<unsigned int>* shndxes
);
5123 #ifdef HAVE_TARGET_64_BIG
5126 Layout::layout_group
<64, true>(Symbol_table
* symtab
,
5127 Sized_relobj_file
<64, true>* object
,
5129 const char* group_section_name
,
5130 const char* signature
,
5131 const elfcpp::Shdr
<64, true>& shdr
,
5132 elfcpp::Elf_Word flags
,
5133 std::vector
<unsigned int>* shndxes
);
5136 #ifdef HAVE_TARGET_32_LITTLE
5139 Layout::layout_eh_frame
<32, false>(Sized_relobj_file
<32, false>* object
,
5140 const unsigned char* symbols
,
5142 const unsigned char* symbol_names
,
5143 off_t symbol_names_size
,
5145 const elfcpp::Shdr
<32, false>& shdr
,
5146 unsigned int reloc_shndx
,
5147 unsigned int reloc_type
,
5151 #ifdef HAVE_TARGET_32_BIG
5154 Layout::layout_eh_frame
<32, true>(Sized_relobj_file
<32, true>* object
,
5155 const unsigned char* symbols
,
5157 const unsigned char* symbol_names
,
5158 off_t symbol_names_size
,
5160 const elfcpp::Shdr
<32, true>& shdr
,
5161 unsigned int reloc_shndx
,
5162 unsigned int reloc_type
,
5166 #ifdef HAVE_TARGET_64_LITTLE
5169 Layout::layout_eh_frame
<64, false>(Sized_relobj_file
<64, false>* object
,
5170 const unsigned char* symbols
,
5172 const unsigned char* symbol_names
,
5173 off_t symbol_names_size
,
5175 const elfcpp::Shdr
<64, false>& shdr
,
5176 unsigned int reloc_shndx
,
5177 unsigned int reloc_type
,
5181 #ifdef HAVE_TARGET_64_BIG
5184 Layout::layout_eh_frame
<64, true>(Sized_relobj_file
<64, true>* object
,
5185 const unsigned char* symbols
,
5187 const unsigned char* symbol_names
,
5188 off_t symbol_names_size
,
5190 const elfcpp::Shdr
<64, true>& shdr
,
5191 unsigned int reloc_shndx
,
5192 unsigned int reloc_type
,
5196 } // End namespace gold.