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 section_ordering_specified_(false),
403 incremental_inputs_(NULL
),
404 record_output_section_data_from_script_(false),
405 script_output_section_data_list_(),
406 segment_states_(NULL
),
407 relaxation_debug_check_(NULL
),
408 input_section_position_(),
409 input_section_glob_(),
410 incremental_base_(NULL
),
413 // Make space for more than enough segments for a typical file.
414 // This is just for efficiency--it's OK if we wind up needing more.
415 this->segment_list_
.reserve(12);
417 // We expect two unattached Output_data objects: the file header and
418 // the segment headers.
419 this->special_output_list_
.reserve(2);
421 // Initialize structure needed for an incremental build.
422 if (parameters
->incremental())
423 this->incremental_inputs_
= new Incremental_inputs
;
425 // The section name pool is worth optimizing in all cases, because
426 // it is small, but there are often overlaps due to .rel sections.
427 this->namepool_
.set_optimize();
430 // For incremental links, record the base file to be modified.
433 Layout::set_incremental_base(Incremental_binary
* base
)
435 this->incremental_base_
= base
;
436 this->free_list_
.init(base
->output_file()->filesize(), true);
439 // Hash a key we use to look up an output section mapping.
442 Layout::Hash_key::operator()(const Layout::Key
& k
) const
444 return k
.first
+ k
.second
.first
+ k
.second
.second
;
447 // Returns whether the given section is in the list of
448 // debug-sections-used-by-some-version-of-gdb. Currently,
449 // we've checked versions of gdb up to and including 6.7.1.
451 static const char* gdb_sections
[] =
453 // ".debug_aranges", // not used by gdb as of 6.7.1
460 // ".debug_pubnames", // not used by gdb as of 6.7.1
465 static const char* lines_only_debug_sections
[] =
467 // ".debug_aranges", // not used by gdb as of 6.7.1
474 // ".debug_pubnames", // not used by gdb as of 6.7.1
480 is_gdb_debug_section(const char* str
)
482 // We can do this faster: binary search or a hashtable. But why bother?
483 for (size_t i
= 0; i
< sizeof(gdb_sections
)/sizeof(*gdb_sections
); ++i
)
484 if (strcmp(str
, gdb_sections
[i
]) == 0)
490 is_lines_only_debug_section(const char* str
)
492 // We can do this faster: binary search or a hashtable. But why bother?
494 i
< sizeof(lines_only_debug_sections
)/sizeof(*lines_only_debug_sections
);
496 if (strcmp(str
, lines_only_debug_sections
[i
]) == 0)
501 // Sometimes we compress sections. This is typically done for
502 // sections that are not part of normal program execution (such as
503 // .debug_* sections), and where the readers of these sections know
504 // how to deal with compressed sections. This routine doesn't say for
505 // certain whether we'll compress -- it depends on commandline options
506 // as well -- just whether this section is a candidate for compression.
507 // (The Output_compressed_section class decides whether to compress
508 // a given section, and picks the name of the compressed section.)
511 is_compressible_debug_section(const char* secname
)
513 return (is_prefix_of(".debug", secname
));
516 // We may see compressed debug sections in input files. Return TRUE
517 // if this is the name of a compressed debug section.
520 is_compressed_debug_section(const char* secname
)
522 return (is_prefix_of(".zdebug", secname
));
525 // Whether to include this section in the link.
527 template<int size
, bool big_endian
>
529 Layout::include_section(Sized_relobj_file
<size
, big_endian
>*, const char* name
,
530 const elfcpp::Shdr
<size
, big_endian
>& shdr
)
532 if (shdr
.get_sh_flags() & elfcpp::SHF_EXCLUDE
)
535 switch (shdr
.get_sh_type())
537 case elfcpp::SHT_NULL
:
538 case elfcpp::SHT_SYMTAB
:
539 case elfcpp::SHT_DYNSYM
:
540 case elfcpp::SHT_HASH
:
541 case elfcpp::SHT_DYNAMIC
:
542 case elfcpp::SHT_SYMTAB_SHNDX
:
545 case elfcpp::SHT_STRTAB
:
546 // Discard the sections which have special meanings in the ELF
547 // ABI. Keep others (e.g., .stabstr). We could also do this by
548 // checking the sh_link fields of the appropriate sections.
549 return (strcmp(name
, ".dynstr") != 0
550 && strcmp(name
, ".strtab") != 0
551 && strcmp(name
, ".shstrtab") != 0);
553 case elfcpp::SHT_RELA
:
554 case elfcpp::SHT_REL
:
555 case elfcpp::SHT_GROUP
:
556 // If we are emitting relocations these should be handled
558 gold_assert(!parameters
->options().relocatable()
559 && !parameters
->options().emit_relocs());
562 case elfcpp::SHT_PROGBITS
:
563 if (parameters
->options().strip_debug()
564 && (shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) == 0)
566 if (is_debug_info_section(name
))
569 if (parameters
->options().strip_debug_non_line()
570 && (shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) == 0)
572 // Debugging sections can only be recognized by name.
573 if (is_prefix_of(".debug", name
)
574 && !is_lines_only_debug_section(name
))
577 if (parameters
->options().strip_debug_gdb()
578 && (shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) == 0)
580 // Debugging sections can only be recognized by name.
581 if (is_prefix_of(".debug", name
)
582 && !is_gdb_debug_section(name
))
585 if (parameters
->options().strip_lto_sections()
586 && !parameters
->options().relocatable()
587 && (shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) == 0)
589 // Ignore LTO sections containing intermediate code.
590 if (is_prefix_of(".gnu.lto_", name
))
593 // The GNU linker strips .gnu_debuglink sections, so we do too.
594 // This is a feature used to keep debugging information in
596 if (strcmp(name
, ".gnu_debuglink") == 0)
605 // Return an output section named NAME, or NULL if there is none.
608 Layout::find_output_section(const char* name
) const
610 for (Section_list::const_iterator p
= this->section_list_
.begin();
611 p
!= this->section_list_
.end();
613 if (strcmp((*p
)->name(), name
) == 0)
618 // Return an output segment of type TYPE, with segment flags SET set
619 // and segment flags CLEAR clear. Return NULL if there is none.
622 Layout::find_output_segment(elfcpp::PT type
, elfcpp::Elf_Word set
,
623 elfcpp::Elf_Word clear
) const
625 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
626 p
!= this->segment_list_
.end();
628 if (static_cast<elfcpp::PT
>((*p
)->type()) == type
629 && ((*p
)->flags() & set
) == set
630 && ((*p
)->flags() & clear
) == 0)
635 // When we put a .ctors or .dtors section with more than one word into
636 // a .init_array or .fini_array section, we need to reverse the words
637 // in the .ctors/.dtors section. This is because .init_array executes
638 // constructors front to back, where .ctors executes them back to
639 // front, and vice-versa for .fini_array/.dtors. Although we do want
640 // to remap .ctors/.dtors into .init_array/.fini_array because it can
641 // be more efficient, we don't want to change the order in which
642 // constructors/destructors are run. This set just keeps track of
643 // these sections which need to be reversed. It is only changed by
644 // Layout::layout. It should be a private member of Layout, but that
645 // would require layout.h to #include object.h to get the definition
647 static Unordered_set
<Section_id
, Section_id_hash
> ctors_sections_in_init_array
;
649 // Return whether OBJECT/SHNDX is a .ctors/.dtors section mapped to a
650 // .init_array/.fini_array section.
653 Layout::is_ctors_in_init_array(Relobj
* relobj
, unsigned int shndx
) const
655 return (ctors_sections_in_init_array
.find(Section_id(relobj
, shndx
))
656 != ctors_sections_in_init_array
.end());
659 // Return the output section to use for section NAME with type TYPE
660 // and section flags FLAGS. NAME must be canonicalized in the string
661 // pool, and NAME_KEY is the key. ORDER is where this should appear
662 // in the output sections. IS_RELRO is true for a relro section.
665 Layout::get_output_section(const char* name
, Stringpool::Key name_key
,
666 elfcpp::Elf_Word type
, elfcpp::Elf_Xword flags
,
667 Output_section_order order
, bool is_relro
)
669 elfcpp::Elf_Word lookup_type
= type
;
671 // For lookup purposes, treat INIT_ARRAY, FINI_ARRAY, and
672 // PREINIT_ARRAY like PROGBITS. This ensures that we combine
673 // .init_array, .fini_array, and .preinit_array sections by name
674 // whatever their type in the input file. We do this because the
675 // types are not always right in the input files.
676 if (lookup_type
== elfcpp::SHT_INIT_ARRAY
677 || lookup_type
== elfcpp::SHT_FINI_ARRAY
678 || lookup_type
== elfcpp::SHT_PREINIT_ARRAY
)
679 lookup_type
= elfcpp::SHT_PROGBITS
;
681 elfcpp::Elf_Xword lookup_flags
= flags
;
683 // Ignoring SHF_WRITE and SHF_EXECINSTR here means that we combine
684 // read-write with read-only sections. Some other ELF linkers do
685 // not do this. FIXME: Perhaps there should be an option
687 lookup_flags
&= ~(elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
);
689 const Key
key(name_key
, std::make_pair(lookup_type
, lookup_flags
));
690 const std::pair
<Key
, Output_section
*> v(key
, NULL
);
691 std::pair
<Section_name_map::iterator
, bool> ins(
692 this->section_name_map_
.insert(v
));
695 return ins
.first
->second
;
698 // This is the first time we've seen this name/type/flags
699 // combination. For compatibility with the GNU linker, we
700 // combine sections with contents and zero flags with sections
701 // with non-zero flags. This is a workaround for cases where
702 // assembler code forgets to set section flags. FIXME: Perhaps
703 // there should be an option to control this.
704 Output_section
* os
= NULL
;
706 if (lookup_type
== elfcpp::SHT_PROGBITS
)
710 Output_section
* same_name
= this->find_output_section(name
);
711 if (same_name
!= NULL
712 && (same_name
->type() == elfcpp::SHT_PROGBITS
713 || same_name
->type() == elfcpp::SHT_INIT_ARRAY
714 || same_name
->type() == elfcpp::SHT_FINI_ARRAY
715 || same_name
->type() == elfcpp::SHT_PREINIT_ARRAY
)
716 && (same_name
->flags() & elfcpp::SHF_TLS
) == 0)
719 else if ((flags
& elfcpp::SHF_TLS
) == 0)
721 elfcpp::Elf_Xword zero_flags
= 0;
722 const Key
zero_key(name_key
, std::make_pair(lookup_type
,
724 Section_name_map::iterator p
=
725 this->section_name_map_
.find(zero_key
);
726 if (p
!= this->section_name_map_
.end())
732 os
= this->make_output_section(name
, type
, flags
, order
, is_relro
);
734 ins
.first
->second
= os
;
739 // Pick the output section to use for section NAME, in input file
740 // RELOBJ, with type TYPE and flags FLAGS. RELOBJ may be NULL for a
741 // linker created section. IS_INPUT_SECTION is true if we are
742 // choosing an output section for an input section found in a input
743 // file. ORDER is where this section should appear in the output
744 // sections. IS_RELRO is true for a relro section. This will return
745 // NULL if the input section should be discarded.
748 Layout::choose_output_section(const Relobj
* relobj
, const char* name
,
749 elfcpp::Elf_Word type
, elfcpp::Elf_Xword flags
,
750 bool is_input_section
, Output_section_order order
,
753 // We should not see any input sections after we have attached
754 // sections to segments.
755 gold_assert(!is_input_section
|| !this->sections_are_attached_
);
757 // Some flags in the input section should not be automatically
758 // copied to the output section.
759 flags
&= ~ (elfcpp::SHF_INFO_LINK
762 | elfcpp::SHF_STRINGS
);
764 // We only clear the SHF_LINK_ORDER flag in for
765 // a non-relocatable link.
766 if (!parameters
->options().relocatable())
767 flags
&= ~elfcpp::SHF_LINK_ORDER
;
769 if (this->script_options_
->saw_sections_clause())
771 // We are using a SECTIONS clause, so the output section is
772 // chosen based only on the name.
774 Script_sections
* ss
= this->script_options_
->script_sections();
775 const char* file_name
= relobj
== NULL
? NULL
: relobj
->name().c_str();
776 Output_section
** output_section_slot
;
777 Script_sections::Section_type script_section_type
;
778 const char* orig_name
= name
;
779 name
= ss
->output_section_name(file_name
, name
, &output_section_slot
,
780 &script_section_type
);
783 gold_debug(DEBUG_SCRIPT
, _("Unable to create output section '%s' "
784 "because it is not allowed by the "
785 "SECTIONS clause of the linker script"),
787 // The SECTIONS clause says to discard this input section.
791 // We can only handle script section types ST_NONE and ST_NOLOAD.
792 switch (script_section_type
)
794 case Script_sections::ST_NONE
:
796 case Script_sections::ST_NOLOAD
:
797 flags
&= elfcpp::SHF_ALLOC
;
803 // If this is an orphan section--one not mentioned in the linker
804 // script--then OUTPUT_SECTION_SLOT will be NULL, and we do the
805 // default processing below.
807 if (output_section_slot
!= NULL
)
809 if (*output_section_slot
!= NULL
)
811 (*output_section_slot
)->update_flags_for_input_section(flags
);
812 return *output_section_slot
;
815 // We don't put sections found in the linker script into
816 // SECTION_NAME_MAP_. That keeps us from getting confused
817 // if an orphan section is mapped to a section with the same
818 // name as one in the linker script.
820 name
= this->namepool_
.add(name
, false, NULL
);
822 Output_section
* os
= this->make_output_section(name
, type
, flags
,
825 os
->set_found_in_sections_clause();
827 // Special handling for NOLOAD sections.
828 if (script_section_type
== Script_sections::ST_NOLOAD
)
832 // The constructor of Output_section sets addresses of non-ALLOC
833 // sections to 0 by default. We don't want that for NOLOAD
834 // sections even if they have no SHF_ALLOC flag.
835 if ((os
->flags() & elfcpp::SHF_ALLOC
) == 0
836 && os
->is_address_valid())
838 gold_assert(os
->address() == 0
839 && !os
->is_offset_valid()
840 && !os
->is_data_size_valid());
841 os
->reset_address_and_file_offset();
845 *output_section_slot
= os
;
850 // FIXME: Handle SHF_OS_NONCONFORMING somewhere.
852 size_t len
= strlen(name
);
853 char* uncompressed_name
= NULL
;
855 // Compressed debug sections should be mapped to the corresponding
856 // uncompressed section.
857 if (is_compressed_debug_section(name
))
859 uncompressed_name
= new char[len
];
860 uncompressed_name
[0] = '.';
861 gold_assert(name
[0] == '.' && name
[1] == 'z');
862 strncpy(&uncompressed_name
[1], &name
[2], len
- 2);
863 uncompressed_name
[len
- 1] = '\0';
865 name
= uncompressed_name
;
868 // Turn NAME from the name of the input section into the name of the
871 && !this->script_options_
->saw_sections_clause()
872 && !parameters
->options().relocatable())
873 name
= Layout::output_section_name(relobj
, name
, &len
);
875 Stringpool::Key name_key
;
876 name
= this->namepool_
.add_with_length(name
, len
, true, &name_key
);
878 if (uncompressed_name
!= NULL
)
879 delete[] uncompressed_name
;
881 // Find or make the output section. The output section is selected
882 // based on the section name, type, and flags.
883 return this->get_output_section(name
, name_key
, type
, flags
, order
, is_relro
);
886 // For incremental links, record the initial fixed layout of a section
887 // from the base file, and return a pointer to the Output_section.
889 template<int size
, bool big_endian
>
891 Layout::init_fixed_output_section(const char* name
,
892 elfcpp::Shdr
<size
, big_endian
>& shdr
)
894 unsigned int sh_type
= shdr
.get_sh_type();
896 // We preserve the layout of PROGBITS, NOBITS, and NOTE sections.
897 // All others will be created from scratch and reallocated.
898 if (sh_type
!= elfcpp::SHT_PROGBITS
899 && sh_type
!= elfcpp::SHT_NOBITS
900 && sh_type
!= elfcpp::SHT_NOTE
)
903 typename
elfcpp::Elf_types
<size
>::Elf_Addr sh_addr
= shdr
.get_sh_addr();
904 typename
elfcpp::Elf_types
<size
>::Elf_Off sh_offset
= shdr
.get_sh_offset();
905 typename
elfcpp::Elf_types
<size
>::Elf_WXword sh_size
= shdr
.get_sh_size();
906 typename
elfcpp::Elf_types
<size
>::Elf_WXword sh_flags
= shdr
.get_sh_flags();
907 typename
elfcpp::Elf_types
<size
>::Elf_WXword sh_addralign
=
908 shdr
.get_sh_addralign();
910 // Make the output section.
911 Stringpool::Key name_key
;
912 name
= this->namepool_
.add(name
, true, &name_key
);
913 Output_section
* os
= this->get_output_section(name
, name_key
, sh_type
,
914 sh_flags
, ORDER_INVALID
, false);
915 os
->set_fixed_layout(sh_addr
, sh_offset
, sh_size
, sh_addralign
);
916 if (sh_type
!= elfcpp::SHT_NOBITS
)
917 this->free_list_
.remove(sh_offset
, sh_offset
+ sh_size
);
921 // Return the output section to use for input section SHNDX, with name
922 // NAME, with header HEADER, from object OBJECT. RELOC_SHNDX is the
923 // index of a relocation section which applies to this section, or 0
924 // if none, or -1U if more than one. RELOC_TYPE is the type of the
925 // relocation section if there is one. Set *OFF to the offset of this
926 // input section without the output section. Return NULL if the
927 // section should be discarded. Set *OFF to -1 if the section
928 // contents should not be written directly to the output file, but
929 // will instead receive special handling.
931 template<int size
, bool big_endian
>
933 Layout::layout(Sized_relobj_file
<size
, big_endian
>* object
, unsigned int shndx
,
934 const char* name
, const elfcpp::Shdr
<size
, big_endian
>& shdr
,
935 unsigned int reloc_shndx
, unsigned int, off_t
* off
)
939 if (!this->include_section(object
, name
, shdr
))
942 elfcpp::Elf_Word sh_type
= shdr
.get_sh_type();
944 // In a relocatable link a grouped section must not be combined with
945 // any other sections.
947 if (parameters
->options().relocatable()
948 && (shdr
.get_sh_flags() & elfcpp::SHF_GROUP
) != 0)
950 name
= this->namepool_
.add(name
, true, NULL
);
951 os
= this->make_output_section(name
, sh_type
, shdr
.get_sh_flags(),
952 ORDER_INVALID
, false);
956 os
= this->choose_output_section(object
, name
, sh_type
,
957 shdr
.get_sh_flags(), true,
958 ORDER_INVALID
, false);
963 // By default the GNU linker sorts input sections whose names match
964 // .ctors.*, .dtors.*, .init_array.*, or .fini_array.*. The
965 // sections are sorted by name. This is used to implement
966 // constructor priority ordering. We are compatible. When we put
967 // .ctor sections in .init_array and .dtor sections in .fini_array,
968 // we must also sort plain .ctor and .dtor sections.
969 if (!this->script_options_
->saw_sections_clause()
970 && !parameters
->options().relocatable()
971 && (is_prefix_of(".ctors.", name
)
972 || is_prefix_of(".dtors.", name
)
973 || is_prefix_of(".init_array.", name
)
974 || is_prefix_of(".fini_array.", name
)
975 || (parameters
->options().ctors_in_init_array()
976 && (strcmp(name
, ".ctors") == 0
977 || strcmp(name
, ".dtors") == 0))))
978 os
->set_must_sort_attached_input_sections();
980 // If this is a .ctors or .ctors.* section being mapped to a
981 // .init_array section, or a .dtors or .dtors.* section being mapped
982 // to a .fini_array section, we will need to reverse the words if
983 // there is more than one. Record this section for later. See
984 // ctors_sections_in_init_array above.
985 if (!this->script_options_
->saw_sections_clause()
986 && !parameters
->options().relocatable()
987 && shdr
.get_sh_size() > size
/ 8
988 && (((strcmp(name
, ".ctors") == 0
989 || is_prefix_of(".ctors.", name
))
990 && strcmp(os
->name(), ".init_array") == 0)
991 || ((strcmp(name
, ".dtors") == 0
992 || is_prefix_of(".dtors.", name
))
993 && strcmp(os
->name(), ".fini_array") == 0)))
994 ctors_sections_in_init_array
.insert(Section_id(object
, shndx
));
996 // FIXME: Handle SHF_LINK_ORDER somewhere.
998 elfcpp::Elf_Xword orig_flags
= os
->flags();
1000 *off
= os
->add_input_section(this, object
, shndx
, name
, shdr
, reloc_shndx
,
1001 this->script_options_
->saw_sections_clause());
1003 // If the flags changed, we may have to change the order.
1004 if ((orig_flags
& elfcpp::SHF_ALLOC
) != 0)
1006 orig_flags
&= (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
);
1007 elfcpp::Elf_Xword new_flags
=
1008 os
->flags() & (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
);
1009 if (orig_flags
!= new_flags
)
1010 os
->set_order(this->default_section_order(os
, false));
1013 this->have_added_input_section_
= true;
1018 // Handle a relocation section when doing a relocatable link.
1020 template<int size
, bool big_endian
>
1022 Layout::layout_reloc(Sized_relobj_file
<size
, big_endian
>* object
,
1024 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
1025 Output_section
* data_section
,
1026 Relocatable_relocs
* rr
)
1028 gold_assert(parameters
->options().relocatable()
1029 || parameters
->options().emit_relocs());
1031 int sh_type
= shdr
.get_sh_type();
1034 if (sh_type
== elfcpp::SHT_REL
)
1036 else if (sh_type
== elfcpp::SHT_RELA
)
1040 name
+= data_section
->name();
1042 // In a relocatable link relocs for a grouped section must not be
1043 // combined with other reloc sections.
1045 if (!parameters
->options().relocatable()
1046 || (data_section
->flags() & elfcpp::SHF_GROUP
) == 0)
1047 os
= this->choose_output_section(object
, name
.c_str(), sh_type
,
1048 shdr
.get_sh_flags(), false,
1049 ORDER_INVALID
, false);
1052 const char* n
= this->namepool_
.add(name
.c_str(), true, NULL
);
1053 os
= this->make_output_section(n
, sh_type
, shdr
.get_sh_flags(),
1054 ORDER_INVALID
, false);
1057 os
->set_should_link_to_symtab();
1058 os
->set_info_section(data_section
);
1060 Output_section_data
* posd
;
1061 if (sh_type
== elfcpp::SHT_REL
)
1063 os
->set_entsize(elfcpp::Elf_sizes
<size
>::rel_size
);
1064 posd
= new Output_relocatable_relocs
<elfcpp::SHT_REL
,
1068 else if (sh_type
== elfcpp::SHT_RELA
)
1070 os
->set_entsize(elfcpp::Elf_sizes
<size
>::rela_size
);
1071 posd
= new Output_relocatable_relocs
<elfcpp::SHT_RELA
,
1078 os
->add_output_section_data(posd
);
1079 rr
->set_output_data(posd
);
1084 // Handle a group section when doing a relocatable link.
1086 template<int size
, bool big_endian
>
1088 Layout::layout_group(Symbol_table
* symtab
,
1089 Sized_relobj_file
<size
, big_endian
>* object
,
1091 const char* group_section_name
,
1092 const char* signature
,
1093 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
1094 elfcpp::Elf_Word flags
,
1095 std::vector
<unsigned int>* shndxes
)
1097 gold_assert(parameters
->options().relocatable());
1098 gold_assert(shdr
.get_sh_type() == elfcpp::SHT_GROUP
);
1099 group_section_name
= this->namepool_
.add(group_section_name
, true, NULL
);
1100 Output_section
* os
= this->make_output_section(group_section_name
,
1102 shdr
.get_sh_flags(),
1103 ORDER_INVALID
, false);
1105 // We need to find a symbol with the signature in the symbol table.
1106 // If we don't find one now, we need to look again later.
1107 Symbol
* sym
= symtab
->lookup(signature
, NULL
);
1109 os
->set_info_symndx(sym
);
1112 // Reserve some space to minimize reallocations.
1113 if (this->group_signatures_
.empty())
1114 this->group_signatures_
.reserve(this->number_of_input_files_
* 16);
1116 // We will wind up using a symbol whose name is the signature.
1117 // So just put the signature in the symbol name pool to save it.
1118 signature
= symtab
->canonicalize_name(signature
);
1119 this->group_signatures_
.push_back(Group_signature(os
, signature
));
1122 os
->set_should_link_to_symtab();
1125 section_size_type entry_count
=
1126 convert_to_section_size_type(shdr
.get_sh_size() / 4);
1127 Output_section_data
* posd
=
1128 new Output_data_group
<size
, big_endian
>(object
, entry_count
, flags
,
1130 os
->add_output_section_data(posd
);
1133 // Special GNU handling of sections name .eh_frame. They will
1134 // normally hold exception frame data as defined by the C++ ABI
1135 // (http://codesourcery.com/cxx-abi/).
1137 template<int size
, bool big_endian
>
1139 Layout::layout_eh_frame(Sized_relobj_file
<size
, big_endian
>* object
,
1140 const unsigned char* symbols
,
1142 const unsigned char* symbol_names
,
1143 off_t symbol_names_size
,
1145 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
1146 unsigned int reloc_shndx
, unsigned int reloc_type
,
1149 gold_assert(shdr
.get_sh_type() == elfcpp::SHT_PROGBITS
1150 || shdr
.get_sh_type() == elfcpp::SHT_X86_64_UNWIND
);
1151 gold_assert((shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) != 0);
1153 Output_section
* os
= this->make_eh_frame_section(object
);
1157 gold_assert(this->eh_frame_section_
== os
);
1159 elfcpp::Elf_Xword orig_flags
= os
->flags();
1161 if (!parameters
->incremental()
1162 && this->eh_frame_data_
->add_ehframe_input_section(object
,
1171 os
->update_flags_for_input_section(shdr
.get_sh_flags());
1173 // A writable .eh_frame section is a RELRO section.
1174 if ((orig_flags
& (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
))
1175 != (os
->flags() & (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
)))
1178 os
->set_order(ORDER_RELRO
);
1181 // We found a .eh_frame section we are going to optimize, so now
1182 // we can add the set of optimized sections to the output
1183 // section. We need to postpone adding this until we've found a
1184 // section we can optimize so that the .eh_frame section in
1185 // crtbegin.o winds up at the start of the output section.
1186 if (!this->added_eh_frame_data_
)
1188 os
->add_output_section_data(this->eh_frame_data_
);
1189 this->added_eh_frame_data_
= true;
1195 // We couldn't handle this .eh_frame section for some reason.
1196 // Add it as a normal section.
1197 bool saw_sections_clause
= this->script_options_
->saw_sections_clause();
1198 *off
= os
->add_input_section(this, object
, shndx
, ".eh_frame", shdr
,
1199 reloc_shndx
, saw_sections_clause
);
1200 this->have_added_input_section_
= true;
1202 if ((orig_flags
& (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
))
1203 != (os
->flags() & (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
)))
1204 os
->set_order(this->default_section_order(os
, false));
1210 // Create and return the magic .eh_frame section. Create
1211 // .eh_frame_hdr also if appropriate. OBJECT is the object with the
1212 // input .eh_frame section; it may be NULL.
1215 Layout::make_eh_frame_section(const Relobj
* object
)
1217 // FIXME: On x86_64, this could use SHT_X86_64_UNWIND rather than
1219 Output_section
* os
= this->choose_output_section(object
, ".eh_frame",
1220 elfcpp::SHT_PROGBITS
,
1221 elfcpp::SHF_ALLOC
, false,
1222 ORDER_EHFRAME
, false);
1226 if (this->eh_frame_section_
== NULL
)
1228 this->eh_frame_section_
= os
;
1229 this->eh_frame_data_
= new Eh_frame();
1231 // For incremental linking, we do not optimize .eh_frame sections
1232 // or create a .eh_frame_hdr section.
1233 if (parameters
->options().eh_frame_hdr() && !parameters
->incremental())
1235 Output_section
* hdr_os
=
1236 this->choose_output_section(NULL
, ".eh_frame_hdr",
1237 elfcpp::SHT_PROGBITS
,
1238 elfcpp::SHF_ALLOC
, false,
1239 ORDER_EHFRAME
, false);
1243 Eh_frame_hdr
* hdr_posd
= new Eh_frame_hdr(os
,
1244 this->eh_frame_data_
);
1245 hdr_os
->add_output_section_data(hdr_posd
);
1247 hdr_os
->set_after_input_sections();
1249 if (!this->script_options_
->saw_phdrs_clause())
1251 Output_segment
* hdr_oseg
;
1252 hdr_oseg
= this->make_output_segment(elfcpp::PT_GNU_EH_FRAME
,
1254 hdr_oseg
->add_output_section_to_nonload(hdr_os
,
1258 this->eh_frame_data_
->set_eh_frame_hdr(hdr_posd
);
1266 // Add an exception frame for a PLT. This is called from target code.
1269 Layout::add_eh_frame_for_plt(Output_data
* plt
, const unsigned char* cie_data
,
1270 size_t cie_length
, const unsigned char* fde_data
,
1273 if (parameters
->incremental())
1275 // FIXME: Maybe this could work some day....
1278 Output_section
* os
= this->make_eh_frame_section(NULL
);
1281 this->eh_frame_data_
->add_ehframe_for_plt(plt
, cie_data
, cie_length
,
1282 fde_data
, fde_length
);
1283 if (!this->added_eh_frame_data_
)
1285 os
->add_output_section_data(this->eh_frame_data_
);
1286 this->added_eh_frame_data_
= true;
1290 // Add POSD to an output section using NAME, TYPE, and FLAGS. Return
1291 // the output section.
1294 Layout::add_output_section_data(const char* name
, elfcpp::Elf_Word type
,
1295 elfcpp::Elf_Xword flags
,
1296 Output_section_data
* posd
,
1297 Output_section_order order
, bool is_relro
)
1299 Output_section
* os
= this->choose_output_section(NULL
, name
, type
, flags
,
1300 false, order
, is_relro
);
1302 os
->add_output_section_data(posd
);
1306 // Map section flags to segment flags.
1309 Layout::section_flags_to_segment(elfcpp::Elf_Xword flags
)
1311 elfcpp::Elf_Word ret
= elfcpp::PF_R
;
1312 if ((flags
& elfcpp::SHF_WRITE
) != 0)
1313 ret
|= elfcpp::PF_W
;
1314 if ((flags
& elfcpp::SHF_EXECINSTR
) != 0)
1315 ret
|= elfcpp::PF_X
;
1319 // Make a new Output_section, and attach it to segments as
1320 // appropriate. ORDER is the order in which this section should
1321 // appear in the output segment. IS_RELRO is true if this is a relro
1322 // (read-only after relocations) section.
1325 Layout::make_output_section(const char* name
, elfcpp::Elf_Word type
,
1326 elfcpp::Elf_Xword flags
,
1327 Output_section_order order
, bool is_relro
)
1330 if ((flags
& elfcpp::SHF_ALLOC
) == 0
1331 && strcmp(parameters
->options().compress_debug_sections(), "none") != 0
1332 && is_compressible_debug_section(name
))
1333 os
= new Output_compressed_section(¶meters
->options(), name
, type
,
1335 else if ((flags
& elfcpp::SHF_ALLOC
) == 0
1336 && parameters
->options().strip_debug_non_line()
1337 && strcmp(".debug_abbrev", name
) == 0)
1339 os
= this->debug_abbrev_
= new Output_reduced_debug_abbrev_section(
1341 if (this->debug_info_
)
1342 this->debug_info_
->set_abbreviations(this->debug_abbrev_
);
1344 else if ((flags
& elfcpp::SHF_ALLOC
) == 0
1345 && parameters
->options().strip_debug_non_line()
1346 && strcmp(".debug_info", name
) == 0)
1348 os
= this->debug_info_
= new Output_reduced_debug_info_section(
1350 if (this->debug_abbrev_
)
1351 this->debug_info_
->set_abbreviations(this->debug_abbrev_
);
1355 // Sometimes .init_array*, .preinit_array* and .fini_array* do
1356 // not have correct section types. Force them here.
1357 if (type
== elfcpp::SHT_PROGBITS
)
1359 if (is_prefix_of(".init_array", name
))
1360 type
= elfcpp::SHT_INIT_ARRAY
;
1361 else if (is_prefix_of(".preinit_array", name
))
1362 type
= elfcpp::SHT_PREINIT_ARRAY
;
1363 else if (is_prefix_of(".fini_array", name
))
1364 type
= elfcpp::SHT_FINI_ARRAY
;
1367 // FIXME: const_cast is ugly.
1368 Target
* target
= const_cast<Target
*>(¶meters
->target());
1369 os
= target
->make_output_section(name
, type
, flags
);
1372 // With -z relro, we have to recognize the special sections by name.
1373 // There is no other way.
1374 bool is_relro_local
= false;
1375 if (!this->script_options_
->saw_sections_clause()
1376 && parameters
->options().relro()
1377 && type
== elfcpp::SHT_PROGBITS
1378 && (flags
& elfcpp::SHF_ALLOC
) != 0
1379 && (flags
& elfcpp::SHF_WRITE
) != 0)
1381 if (strcmp(name
, ".data.rel.ro") == 0)
1383 else if (strcmp(name
, ".data.rel.ro.local") == 0)
1386 is_relro_local
= true;
1388 else if (type
== elfcpp::SHT_INIT_ARRAY
1389 || type
== elfcpp::SHT_FINI_ARRAY
1390 || type
== elfcpp::SHT_PREINIT_ARRAY
)
1392 else if (strcmp(name
, ".ctors") == 0
1393 || strcmp(name
, ".dtors") == 0
1394 || strcmp(name
, ".jcr") == 0)
1401 if (order
== ORDER_INVALID
&& (flags
& elfcpp::SHF_ALLOC
) != 0)
1402 order
= this->default_section_order(os
, is_relro_local
);
1404 os
->set_order(order
);
1406 parameters
->target().new_output_section(os
);
1408 this->section_list_
.push_back(os
);
1410 // The GNU linker by default sorts some sections by priority, so we
1411 // do the same. We need to know that this might happen before we
1412 // attach any input sections.
1413 if (!this->script_options_
->saw_sections_clause()
1414 && !parameters
->options().relocatable()
1415 && (strcmp(name
, ".init_array") == 0
1416 || strcmp(name
, ".fini_array") == 0
1417 || (!parameters
->options().ctors_in_init_array()
1418 && (strcmp(name
, ".ctors") == 0
1419 || strcmp(name
, ".dtors") == 0))))
1420 os
->set_may_sort_attached_input_sections();
1422 // Check for .stab*str sections, as .stab* sections need to link to
1424 if (type
== elfcpp::SHT_STRTAB
1425 && !this->have_stabstr_section_
1426 && strncmp(name
, ".stab", 5) == 0
1427 && strcmp(name
+ strlen(name
) - 3, "str") == 0)
1428 this->have_stabstr_section_
= true;
1430 // During a full incremental link, we add patch space to most
1431 // PROGBITS and NOBITS sections. Flag those that may be
1432 // arbitrarily padded.
1433 if ((type
== elfcpp::SHT_PROGBITS
|| type
== elfcpp::SHT_NOBITS
)
1434 && order
!= ORDER_INTERP
1435 && order
!= ORDER_INIT
1436 && order
!= ORDER_PLT
1437 && order
!= ORDER_FINI
1438 && order
!= ORDER_RELRO_LAST
1439 && order
!= ORDER_NON_RELRO_FIRST
1440 && strcmp(name
, ".ctors") != 0
1441 && strcmp(name
, ".dtors") != 0
1442 && strcmp(name
, ".jcr") != 0)
1443 os
->set_is_patch_space_allowed();
1445 // If we have already attached the sections to segments, then we
1446 // need to attach this one now. This happens for sections created
1447 // directly by the linker.
1448 if (this->sections_are_attached_
)
1449 this->attach_section_to_segment(os
);
1454 // Return the default order in which a section should be placed in an
1455 // output segment. This function captures a lot of the ideas in
1456 // ld/scripttempl/elf.sc in the GNU linker. Note that the order of a
1457 // linker created section is normally set when the section is created;
1458 // this function is used for input sections.
1460 Output_section_order
1461 Layout::default_section_order(Output_section
* os
, bool is_relro_local
)
1463 gold_assert((os
->flags() & elfcpp::SHF_ALLOC
) != 0);
1464 bool is_write
= (os
->flags() & elfcpp::SHF_WRITE
) != 0;
1465 bool is_execinstr
= (os
->flags() & elfcpp::SHF_EXECINSTR
) != 0;
1466 bool is_bss
= false;
1471 case elfcpp::SHT_PROGBITS
:
1473 case elfcpp::SHT_NOBITS
:
1476 case elfcpp::SHT_RELA
:
1477 case elfcpp::SHT_REL
:
1479 return ORDER_DYNAMIC_RELOCS
;
1481 case elfcpp::SHT_HASH
:
1482 case elfcpp::SHT_DYNAMIC
:
1483 case elfcpp::SHT_SHLIB
:
1484 case elfcpp::SHT_DYNSYM
:
1485 case elfcpp::SHT_GNU_HASH
:
1486 case elfcpp::SHT_GNU_verdef
:
1487 case elfcpp::SHT_GNU_verneed
:
1488 case elfcpp::SHT_GNU_versym
:
1490 return ORDER_DYNAMIC_LINKER
;
1492 case elfcpp::SHT_NOTE
:
1493 return is_write
? ORDER_RW_NOTE
: ORDER_RO_NOTE
;
1496 if ((os
->flags() & elfcpp::SHF_TLS
) != 0)
1497 return is_bss
? ORDER_TLS_BSS
: ORDER_TLS_DATA
;
1499 if (!is_bss
&& !is_write
)
1503 if (strcmp(os
->name(), ".init") == 0)
1505 else if (strcmp(os
->name(), ".fini") == 0)
1508 return is_execinstr
? ORDER_TEXT
: ORDER_READONLY
;
1512 return is_relro_local
? ORDER_RELRO_LOCAL
: ORDER_RELRO
;
1514 if (os
->is_small_section())
1515 return is_bss
? ORDER_SMALL_BSS
: ORDER_SMALL_DATA
;
1516 if (os
->is_large_section())
1517 return is_bss
? ORDER_LARGE_BSS
: ORDER_LARGE_DATA
;
1519 return is_bss
? ORDER_BSS
: ORDER_DATA
;
1522 // Attach output sections to segments. This is called after we have
1523 // seen all the input sections.
1526 Layout::attach_sections_to_segments()
1528 for (Section_list::iterator p
= this->section_list_
.begin();
1529 p
!= this->section_list_
.end();
1531 this->attach_section_to_segment(*p
);
1533 this->sections_are_attached_
= true;
1536 // Attach an output section to a segment.
1539 Layout::attach_section_to_segment(Output_section
* os
)
1541 if ((os
->flags() & elfcpp::SHF_ALLOC
) == 0)
1542 this->unattached_section_list_
.push_back(os
);
1544 this->attach_allocated_section_to_segment(os
);
1547 // Attach an allocated output section to a segment.
1550 Layout::attach_allocated_section_to_segment(Output_section
* os
)
1552 elfcpp::Elf_Xword flags
= os
->flags();
1553 gold_assert((flags
& elfcpp::SHF_ALLOC
) != 0);
1555 if (parameters
->options().relocatable())
1558 // If we have a SECTIONS clause, we can't handle the attachment to
1559 // segments until after we've seen all the sections.
1560 if (this->script_options_
->saw_sections_clause())
1563 gold_assert(!this->script_options_
->saw_phdrs_clause());
1565 // This output section goes into a PT_LOAD segment.
1567 elfcpp::Elf_Word seg_flags
= Layout::section_flags_to_segment(flags
);
1569 // Check for --section-start.
1571 bool is_address_set
= parameters
->options().section_start(os
->name(), &addr
);
1573 // In general the only thing we really care about for PT_LOAD
1574 // segments is whether or not they are writable or executable,
1575 // so that is how we search for them.
1576 // Large data sections also go into their own PT_LOAD segment.
1577 // People who need segments sorted on some other basis will
1578 // have to use a linker script.
1580 Segment_list::const_iterator p
;
1581 for (p
= this->segment_list_
.begin();
1582 p
!= this->segment_list_
.end();
1585 if ((*p
)->type() != elfcpp::PT_LOAD
)
1587 if (!parameters
->options().omagic()
1588 && ((*p
)->flags() & elfcpp::PF_W
) != (seg_flags
& elfcpp::PF_W
))
1590 if (parameters
->options().rosegment()
1591 && ((*p
)->flags() & elfcpp::PF_X
) != (seg_flags
& elfcpp::PF_X
))
1593 // If -Tbss was specified, we need to separate the data and BSS
1595 if (parameters
->options().user_set_Tbss())
1597 if ((os
->type() == elfcpp::SHT_NOBITS
)
1598 == (*p
)->has_any_data_sections())
1601 if (os
->is_large_data_section() && !(*p
)->is_large_data_segment())
1606 if ((*p
)->are_addresses_set())
1609 (*p
)->add_initial_output_data(os
);
1610 (*p
)->update_flags_for_output_section(seg_flags
);
1611 (*p
)->set_addresses(addr
, addr
);
1615 (*p
)->add_output_section_to_load(this, os
, seg_flags
);
1619 if (p
== this->segment_list_
.end())
1621 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_LOAD
,
1623 if (os
->is_large_data_section())
1624 oseg
->set_is_large_data_segment();
1625 oseg
->add_output_section_to_load(this, os
, seg_flags
);
1627 oseg
->set_addresses(addr
, addr
);
1630 // If we see a loadable SHT_NOTE section, we create a PT_NOTE
1632 if (os
->type() == elfcpp::SHT_NOTE
)
1634 // See if we already have an equivalent PT_NOTE segment.
1635 for (p
= this->segment_list_
.begin();
1636 p
!= segment_list_
.end();
1639 if ((*p
)->type() == elfcpp::PT_NOTE
1640 && (((*p
)->flags() & elfcpp::PF_W
)
1641 == (seg_flags
& elfcpp::PF_W
)))
1643 (*p
)->add_output_section_to_nonload(os
, seg_flags
);
1648 if (p
== this->segment_list_
.end())
1650 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_NOTE
,
1652 oseg
->add_output_section_to_nonload(os
, seg_flags
);
1656 // If we see a loadable SHF_TLS section, we create a PT_TLS
1657 // segment. There can only be one such segment.
1658 if ((flags
& elfcpp::SHF_TLS
) != 0)
1660 if (this->tls_segment_
== NULL
)
1661 this->make_output_segment(elfcpp::PT_TLS
, seg_flags
);
1662 this->tls_segment_
->add_output_section_to_nonload(os
, seg_flags
);
1665 // If -z relro is in effect, and we see a relro section, we create a
1666 // PT_GNU_RELRO segment. There can only be one such segment.
1667 if (os
->is_relro() && parameters
->options().relro())
1669 gold_assert(seg_flags
== (elfcpp::PF_R
| elfcpp::PF_W
));
1670 if (this->relro_segment_
== NULL
)
1671 this->make_output_segment(elfcpp::PT_GNU_RELRO
, seg_flags
);
1672 this->relro_segment_
->add_output_section_to_nonload(os
, seg_flags
);
1675 // If we see a section named .interp, put it into a PT_INTERP
1676 // segment. This seems broken to me, but this is what GNU ld does,
1677 // and glibc expects it.
1678 if (strcmp(os
->name(), ".interp") == 0
1679 && !this->script_options_
->saw_phdrs_clause())
1681 if (this->interp_segment_
== NULL
)
1682 this->make_output_segment(elfcpp::PT_INTERP
, seg_flags
);
1684 gold_warning(_("multiple '.interp' sections in input files "
1685 "may cause confusing PT_INTERP segment"));
1686 this->interp_segment_
->add_output_section_to_nonload(os
, seg_flags
);
1690 // Make an output section for a script.
1693 Layout::make_output_section_for_script(
1695 Script_sections::Section_type section_type
)
1697 name
= this->namepool_
.add(name
, false, NULL
);
1698 elfcpp::Elf_Xword sh_flags
= elfcpp::SHF_ALLOC
;
1699 if (section_type
== Script_sections::ST_NOLOAD
)
1701 Output_section
* os
= this->make_output_section(name
, elfcpp::SHT_PROGBITS
,
1702 sh_flags
, ORDER_INVALID
,
1704 os
->set_found_in_sections_clause();
1705 if (section_type
== Script_sections::ST_NOLOAD
)
1706 os
->set_is_noload();
1710 // Return the number of segments we expect to see.
1713 Layout::expected_segment_count() const
1715 size_t ret
= this->segment_list_
.size();
1717 // If we didn't see a SECTIONS clause in a linker script, we should
1718 // already have the complete list of segments. Otherwise we ask the
1719 // SECTIONS clause how many segments it expects, and add in the ones
1720 // we already have (PT_GNU_STACK, PT_GNU_EH_FRAME, etc.)
1722 if (!this->script_options_
->saw_sections_clause())
1726 const Script_sections
* ss
= this->script_options_
->script_sections();
1727 return ret
+ ss
->expected_segment_count(this);
1731 // Handle the .note.GNU-stack section at layout time. SEEN_GNU_STACK
1732 // is whether we saw a .note.GNU-stack section in the object file.
1733 // GNU_STACK_FLAGS is the section flags. The flags give the
1734 // protection required for stack memory. We record this in an
1735 // executable as a PT_GNU_STACK segment. If an object file does not
1736 // have a .note.GNU-stack segment, we must assume that it is an old
1737 // object. On some targets that will force an executable stack.
1740 Layout::layout_gnu_stack(bool seen_gnu_stack
, uint64_t gnu_stack_flags
,
1743 if (!seen_gnu_stack
)
1745 this->input_without_gnu_stack_note_
= true;
1746 if (parameters
->options().warn_execstack()
1747 && parameters
->target().is_default_stack_executable())
1748 gold_warning(_("%s: missing .note.GNU-stack section"
1749 " implies executable stack"),
1750 obj
->name().c_str());
1754 this->input_with_gnu_stack_note_
= true;
1755 if ((gnu_stack_flags
& elfcpp::SHF_EXECINSTR
) != 0)
1757 this->input_requires_executable_stack_
= true;
1758 if (parameters
->options().warn_execstack()
1759 || parameters
->options().is_stack_executable())
1760 gold_warning(_("%s: requires executable stack"),
1761 obj
->name().c_str());
1766 // Create automatic note sections.
1769 Layout::create_notes()
1771 this->create_gold_note();
1772 this->create_executable_stack_info();
1773 this->create_build_id();
1776 // Create the dynamic sections which are needed before we read the
1780 Layout::create_initial_dynamic_sections(Symbol_table
* symtab
)
1782 if (parameters
->doing_static_link())
1785 this->dynamic_section_
= this->choose_output_section(NULL
, ".dynamic",
1786 elfcpp::SHT_DYNAMIC
,
1788 | elfcpp::SHF_WRITE
),
1792 // A linker script may discard .dynamic, so check for NULL.
1793 if (this->dynamic_section_
!= NULL
)
1795 this->dynamic_symbol_
=
1796 symtab
->define_in_output_data("_DYNAMIC", NULL
,
1797 Symbol_table::PREDEFINED
,
1798 this->dynamic_section_
, 0, 0,
1799 elfcpp::STT_OBJECT
, elfcpp::STB_LOCAL
,
1800 elfcpp::STV_HIDDEN
, 0, false, false);
1802 this->dynamic_data_
= new Output_data_dynamic(&this->dynpool_
);
1804 this->dynamic_section_
->add_output_section_data(this->dynamic_data_
);
1808 // For each output section whose name can be represented as C symbol,
1809 // define __start and __stop symbols for the section. This is a GNU
1813 Layout::define_section_symbols(Symbol_table
* symtab
)
1815 for (Section_list::const_iterator p
= this->section_list_
.begin();
1816 p
!= this->section_list_
.end();
1819 const char* const name
= (*p
)->name();
1820 if (is_cident(name
))
1822 const std::string
name_string(name
);
1823 const std::string
start_name(cident_section_start_prefix
1825 const std::string
stop_name(cident_section_stop_prefix
1828 symtab
->define_in_output_data(start_name
.c_str(),
1830 Symbol_table::PREDEFINED
,
1836 elfcpp::STV_DEFAULT
,
1838 false, // offset_is_from_end
1839 true); // only_if_ref
1841 symtab
->define_in_output_data(stop_name
.c_str(),
1843 Symbol_table::PREDEFINED
,
1849 elfcpp::STV_DEFAULT
,
1851 true, // offset_is_from_end
1852 true); // only_if_ref
1857 // Define symbols for group signatures.
1860 Layout::define_group_signatures(Symbol_table
* symtab
)
1862 for (Group_signatures::iterator p
= this->group_signatures_
.begin();
1863 p
!= this->group_signatures_
.end();
1866 Symbol
* sym
= symtab
->lookup(p
->signature
, NULL
);
1868 p
->section
->set_info_symndx(sym
);
1871 // Force the name of the group section to the group
1872 // signature, and use the group's section symbol as the
1873 // signature symbol.
1874 if (strcmp(p
->section
->name(), p
->signature
) != 0)
1876 const char* name
= this->namepool_
.add(p
->signature
,
1878 p
->section
->set_name(name
);
1880 p
->section
->set_needs_symtab_index();
1881 p
->section
->set_info_section_symndx(p
->section
);
1885 this->group_signatures_
.clear();
1888 // Find the first read-only PT_LOAD segment, creating one if
1892 Layout::find_first_load_seg()
1894 Output_segment
* best
= NULL
;
1895 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
1896 p
!= this->segment_list_
.end();
1899 if ((*p
)->type() == elfcpp::PT_LOAD
1900 && ((*p
)->flags() & elfcpp::PF_R
) != 0
1901 && (parameters
->options().omagic()
1902 || ((*p
)->flags() & elfcpp::PF_W
) == 0))
1904 if (best
== NULL
|| this->segment_precedes(*p
, best
))
1911 gold_assert(!this->script_options_
->saw_phdrs_clause());
1913 Output_segment
* load_seg
= this->make_output_segment(elfcpp::PT_LOAD
,
1918 // Save states of all current output segments. Store saved states
1919 // in SEGMENT_STATES.
1922 Layout::save_segments(Segment_states
* segment_states
)
1924 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
1925 p
!= this->segment_list_
.end();
1928 Output_segment
* segment
= *p
;
1930 Output_segment
* copy
= new Output_segment(*segment
);
1931 (*segment_states
)[segment
] = copy
;
1935 // Restore states of output segments and delete any segment not found in
1939 Layout::restore_segments(const Segment_states
* segment_states
)
1941 // Go through the segment list and remove any segment added in the
1943 this->tls_segment_
= NULL
;
1944 this->relro_segment_
= NULL
;
1945 Segment_list::iterator list_iter
= this->segment_list_
.begin();
1946 while (list_iter
!= this->segment_list_
.end())
1948 Output_segment
* segment
= *list_iter
;
1949 Segment_states::const_iterator states_iter
=
1950 segment_states
->find(segment
);
1951 if (states_iter
!= segment_states
->end())
1953 const Output_segment
* copy
= states_iter
->second
;
1954 // Shallow copy to restore states.
1957 // Also fix up TLS and RELRO segment pointers as appropriate.
1958 if (segment
->type() == elfcpp::PT_TLS
)
1959 this->tls_segment_
= segment
;
1960 else if (segment
->type() == elfcpp::PT_GNU_RELRO
)
1961 this->relro_segment_
= segment
;
1967 list_iter
= this->segment_list_
.erase(list_iter
);
1968 // This is a segment created during section layout. It should be
1969 // safe to remove it since we should have removed all pointers to it.
1975 // Clean up after relaxation so that sections can be laid out again.
1978 Layout::clean_up_after_relaxation()
1980 // Restore the segments to point state just prior to the relaxation loop.
1981 Script_sections
* script_section
= this->script_options_
->script_sections();
1982 script_section
->release_segments();
1983 this->restore_segments(this->segment_states_
);
1985 // Reset section addresses and file offsets
1986 for (Section_list::iterator p
= this->section_list_
.begin();
1987 p
!= this->section_list_
.end();
1990 (*p
)->restore_states();
1992 // If an input section changes size because of relaxation,
1993 // we need to adjust the section offsets of all input sections.
1994 // after such a section.
1995 if ((*p
)->section_offsets_need_adjustment())
1996 (*p
)->adjust_section_offsets();
1998 (*p
)->reset_address_and_file_offset();
2001 // Reset special output object address and file offsets.
2002 for (Data_list::iterator p
= this->special_output_list_
.begin();
2003 p
!= this->special_output_list_
.end();
2005 (*p
)->reset_address_and_file_offset();
2007 // A linker script may have created some output section data objects.
2008 // They are useless now.
2009 for (Output_section_data_list::const_iterator p
=
2010 this->script_output_section_data_list_
.begin();
2011 p
!= this->script_output_section_data_list_
.end();
2014 this->script_output_section_data_list_
.clear();
2017 // Prepare for relaxation.
2020 Layout::prepare_for_relaxation()
2022 // Create an relaxation debug check if in debugging mode.
2023 if (is_debugging_enabled(DEBUG_RELAXATION
))
2024 this->relaxation_debug_check_
= new Relaxation_debug_check();
2026 // Save segment states.
2027 this->segment_states_
= new Segment_states();
2028 this->save_segments(this->segment_states_
);
2030 for(Section_list::const_iterator p
= this->section_list_
.begin();
2031 p
!= this->section_list_
.end();
2033 (*p
)->save_states();
2035 if (is_debugging_enabled(DEBUG_RELAXATION
))
2036 this->relaxation_debug_check_
->check_output_data_for_reset_values(
2037 this->section_list_
, this->special_output_list_
);
2039 // Also enable recording of output section data from scripts.
2040 this->record_output_section_data_from_script_
= true;
2043 // Relaxation loop body: If target has no relaxation, this runs only once
2044 // Otherwise, the target relaxation hook is called at the end of
2045 // each iteration. If the hook returns true, it means re-layout of
2046 // section is required.
2048 // The number of segments created by a linking script without a PHDRS
2049 // clause may be affected by section sizes and alignments. There is
2050 // a remote chance that relaxation causes different number of PT_LOAD
2051 // segments are created and sections are attached to different segments.
2052 // Therefore, we always throw away all segments created during section
2053 // layout. In order to be able to restart the section layout, we keep
2054 // a copy of the segment list right before the relaxation loop and use
2055 // that to restore the segments.
2057 // PASS is the current relaxation pass number.
2058 // SYMTAB is a symbol table.
2059 // PLOAD_SEG is the address of a pointer for the load segment.
2060 // PHDR_SEG is a pointer to the PHDR segment.
2061 // SEGMENT_HEADERS points to the output segment header.
2062 // FILE_HEADER points to the output file header.
2063 // PSHNDX is the address to store the output section index.
2066 Layout::relaxation_loop_body(
2069 Symbol_table
* symtab
,
2070 Output_segment
** pload_seg
,
2071 Output_segment
* phdr_seg
,
2072 Output_segment_headers
* segment_headers
,
2073 Output_file_header
* file_header
,
2074 unsigned int* pshndx
)
2076 // If this is not the first iteration, we need to clean up after
2077 // relaxation so that we can lay out the sections again.
2079 this->clean_up_after_relaxation();
2081 // If there is a SECTIONS clause, put all the input sections into
2082 // the required order.
2083 Output_segment
* load_seg
;
2084 if (this->script_options_
->saw_sections_clause())
2085 load_seg
= this->set_section_addresses_from_script(symtab
);
2086 else if (parameters
->options().relocatable())
2089 load_seg
= this->find_first_load_seg();
2091 if (parameters
->options().oformat_enum()
2092 != General_options::OBJECT_FORMAT_ELF
)
2095 // If the user set the address of the text segment, that may not be
2096 // compatible with putting the segment headers and file headers into
2098 if (parameters
->options().user_set_Ttext())
2101 gold_assert(phdr_seg
== NULL
2103 || this->script_options_
->saw_sections_clause());
2105 // If the address of the load segment we found has been set by
2106 // --section-start rather than by a script, then adjust the VMA and
2107 // LMA downward if possible to include the file and section headers.
2108 uint64_t header_gap
= 0;
2109 if (load_seg
!= NULL
2110 && load_seg
->are_addresses_set()
2111 && !this->script_options_
->saw_sections_clause()
2112 && !parameters
->options().relocatable())
2114 file_header
->finalize_data_size();
2115 segment_headers
->finalize_data_size();
2116 size_t sizeof_headers
= (file_header
->data_size()
2117 + segment_headers
->data_size());
2118 const uint64_t abi_pagesize
= target
->abi_pagesize();
2119 uint64_t hdr_paddr
= load_seg
->paddr() - sizeof_headers
;
2120 hdr_paddr
&= ~(abi_pagesize
- 1);
2121 uint64_t subtract
= load_seg
->paddr() - hdr_paddr
;
2122 if (load_seg
->paddr() < subtract
|| load_seg
->vaddr() < subtract
)
2126 load_seg
->set_addresses(load_seg
->vaddr() - subtract
,
2127 load_seg
->paddr() - subtract
);
2128 header_gap
= subtract
- sizeof_headers
;
2132 // Lay out the segment headers.
2133 if (!parameters
->options().relocatable())
2135 gold_assert(segment_headers
!= NULL
);
2136 if (header_gap
!= 0 && load_seg
!= NULL
)
2138 Output_data_zero_fill
* z
= new Output_data_zero_fill(header_gap
, 1);
2139 load_seg
->add_initial_output_data(z
);
2141 if (load_seg
!= NULL
)
2142 load_seg
->add_initial_output_data(segment_headers
);
2143 if (phdr_seg
!= NULL
)
2144 phdr_seg
->add_initial_output_data(segment_headers
);
2147 // Lay out the file header.
2148 if (load_seg
!= NULL
)
2149 load_seg
->add_initial_output_data(file_header
);
2151 if (this->script_options_
->saw_phdrs_clause()
2152 && !parameters
->options().relocatable())
2154 // Support use of FILEHDRS and PHDRS attachments in a PHDRS
2155 // clause in a linker script.
2156 Script_sections
* ss
= this->script_options_
->script_sections();
2157 ss
->put_headers_in_phdrs(file_header
, segment_headers
);
2160 // We set the output section indexes in set_segment_offsets and
2161 // set_section_indexes.
2164 // Set the file offsets of all the segments, and all the sections
2167 if (!parameters
->options().relocatable())
2168 off
= this->set_segment_offsets(target
, load_seg
, pshndx
);
2170 off
= this->set_relocatable_section_offsets(file_header
, pshndx
);
2172 // Verify that the dummy relaxation does not change anything.
2173 if (is_debugging_enabled(DEBUG_RELAXATION
))
2176 this->relaxation_debug_check_
->read_sections(this->section_list_
);
2178 this->relaxation_debug_check_
->verify_sections(this->section_list_
);
2181 *pload_seg
= load_seg
;
2185 // Search the list of patterns and find the postion of the given section
2186 // name in the output section. If the section name matches a glob
2187 // pattern and a non-glob name, then the non-glob position takes
2188 // precedence. Return 0 if no match is found.
2191 Layout::find_section_order_index(const std::string
& section_name
)
2193 Unordered_map
<std::string
, unsigned int>::iterator map_it
;
2194 map_it
= this->input_section_position_
.find(section_name
);
2195 if (map_it
!= this->input_section_position_
.end())
2196 return map_it
->second
;
2198 // Absolute match failed. Linear search the glob patterns.
2199 std::vector
<std::string
>::iterator it
;
2200 for (it
= this->input_section_glob_
.begin();
2201 it
!= this->input_section_glob_
.end();
2204 if (fnmatch((*it
).c_str(), section_name
.c_str(), FNM_NOESCAPE
) == 0)
2206 map_it
= this->input_section_position_
.find(*it
);
2207 gold_assert(map_it
!= this->input_section_position_
.end());
2208 return map_it
->second
;
2214 // Read the sequence of input sections from the file specified with
2215 // option --section-ordering-file.
2218 Layout::read_layout_from_file()
2220 const char* filename
= parameters
->options().section_ordering_file();
2226 gold_fatal(_("unable to open --section-ordering-file file %s: %s"),
2227 filename
, strerror(errno
));
2229 std::getline(in
, line
); // this chops off the trailing \n, if any
2230 unsigned int position
= 1;
2231 this->set_section_ordering_specified();
2235 if (!line
.empty() && line
[line
.length() - 1] == '\r') // Windows
2236 line
.resize(line
.length() - 1);
2237 // Ignore comments, beginning with '#'
2240 std::getline(in
, line
);
2243 this->input_section_position_
[line
] = position
;
2244 // Store all glob patterns in a vector.
2245 if (is_wildcard_string(line
.c_str()))
2246 this->input_section_glob_
.push_back(line
);
2248 std::getline(in
, line
);
2252 // Finalize the layout. When this is called, we have created all the
2253 // output sections and all the output segments which are based on
2254 // input sections. We have several things to do, and we have to do
2255 // them in the right order, so that we get the right results correctly
2258 // 1) Finalize the list of output segments and create the segment
2261 // 2) Finalize the dynamic symbol table and associated sections.
2263 // 3) Determine the final file offset of all the output segments.
2265 // 4) Determine the final file offset of all the SHF_ALLOC output
2268 // 5) Create the symbol table sections and the section name table
2271 // 6) Finalize the symbol table: set symbol values to their final
2272 // value and make a final determination of which symbols are going
2273 // into the output symbol table.
2275 // 7) Create the section table header.
2277 // 8) Determine the final file offset of all the output sections which
2278 // are not SHF_ALLOC, including the section table header.
2280 // 9) Finalize the ELF file header.
2282 // This function returns the size of the output file.
2285 Layout::finalize(const Input_objects
* input_objects
, Symbol_table
* symtab
,
2286 Target
* target
, const Task
* task
)
2288 target
->finalize_sections(this, input_objects
, symtab
);
2290 this->count_local_symbols(task
, input_objects
);
2292 this->link_stabs_sections();
2294 Output_segment
* phdr_seg
= NULL
;
2295 if (!parameters
->options().relocatable() && !parameters
->doing_static_link())
2297 // There was a dynamic object in the link. We need to create
2298 // some information for the dynamic linker.
2300 // Create the PT_PHDR segment which will hold the program
2302 if (!this->script_options_
->saw_phdrs_clause())
2303 phdr_seg
= this->make_output_segment(elfcpp::PT_PHDR
, elfcpp::PF_R
);
2305 // Create the dynamic symbol table, including the hash table.
2306 Output_section
* dynstr
;
2307 std::vector
<Symbol
*> dynamic_symbols
;
2308 unsigned int local_dynamic_count
;
2309 Versions
versions(*this->script_options()->version_script_info(),
2311 this->create_dynamic_symtab(input_objects
, symtab
, &dynstr
,
2312 &local_dynamic_count
, &dynamic_symbols
,
2315 // Create the .interp section to hold the name of the
2316 // interpreter, and put it in a PT_INTERP segment. Don't do it
2317 // if we saw a .interp section in an input file.
2318 if ((!parameters
->options().shared()
2319 || parameters
->options().dynamic_linker() != NULL
)
2320 && this->interp_segment_
== NULL
)
2321 this->create_interp(target
);
2323 // Finish the .dynamic section to hold the dynamic data, and put
2324 // it in a PT_DYNAMIC segment.
2325 this->finish_dynamic_section(input_objects
, symtab
);
2327 // We should have added everything we need to the dynamic string
2329 this->dynpool_
.set_string_offsets();
2331 // Create the version sections. We can't do this until the
2332 // dynamic string table is complete.
2333 this->create_version_sections(&versions
, symtab
, local_dynamic_count
,
2334 dynamic_symbols
, dynstr
);
2336 // Set the size of the _DYNAMIC symbol. We can't do this until
2337 // after we call create_version_sections.
2338 this->set_dynamic_symbol_size(symtab
);
2341 // Create segment headers.
2342 Output_segment_headers
* segment_headers
=
2343 (parameters
->options().relocatable()
2345 : new Output_segment_headers(this->segment_list_
));
2347 // Lay out the file header.
2348 Output_file_header
* file_header
= new Output_file_header(target
, symtab
,
2351 this->special_output_list_
.push_back(file_header
);
2352 if (segment_headers
!= NULL
)
2353 this->special_output_list_
.push_back(segment_headers
);
2355 // Find approriate places for orphan output sections if we are using
2357 if (this->script_options_
->saw_sections_clause())
2358 this->place_orphan_sections_in_script();
2360 Output_segment
* load_seg
;
2365 // Take a snapshot of the section layout as needed.
2366 if (target
->may_relax())
2367 this->prepare_for_relaxation();
2369 // Run the relaxation loop to lay out sections.
2372 off
= this->relaxation_loop_body(pass
, target
, symtab
, &load_seg
,
2373 phdr_seg
, segment_headers
, file_header
,
2377 while (target
->may_relax()
2378 && target
->relax(pass
, input_objects
, symtab
, this, task
));
2380 // Set the file offsets of all the non-data sections we've seen so
2381 // far which don't have to wait for the input sections. We need
2382 // this in order to finalize local symbols in non-allocated
2384 off
= this->set_section_offsets(off
, BEFORE_INPUT_SECTIONS_PASS
);
2386 // Set the section indexes of all unallocated sections seen so far,
2387 // in case any of them are somehow referenced by a symbol.
2388 shndx
= this->set_section_indexes(shndx
);
2390 // Create the symbol table sections.
2391 this->create_symtab_sections(input_objects
, symtab
, shndx
, &off
);
2392 if (!parameters
->doing_static_link())
2393 this->assign_local_dynsym_offsets(input_objects
);
2395 // Process any symbol assignments from a linker script. This must
2396 // be called after the symbol table has been finalized.
2397 this->script_options_
->finalize_symbols(symtab
, this);
2399 // Create the incremental inputs sections.
2400 if (this->incremental_inputs_
)
2402 this->incremental_inputs_
->finalize();
2403 this->create_incremental_info_sections(symtab
);
2406 // Create the .shstrtab section.
2407 Output_section
* shstrtab_section
= this->create_shstrtab();
2409 // Set the file offsets of the rest of the non-data sections which
2410 // don't have to wait for the input sections.
2411 off
= this->set_section_offsets(off
, BEFORE_INPUT_SECTIONS_PASS
);
2413 // Now that all sections have been created, set the section indexes
2414 // for any sections which haven't been done yet.
2415 shndx
= this->set_section_indexes(shndx
);
2417 // Create the section table header.
2418 this->create_shdrs(shstrtab_section
, &off
);
2420 // If there are no sections which require postprocessing, we can
2421 // handle the section names now, and avoid a resize later.
2422 if (!this->any_postprocessing_sections_
)
2424 off
= this->set_section_offsets(off
,
2425 POSTPROCESSING_SECTIONS_PASS
);
2427 this->set_section_offsets(off
,
2428 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
);
2431 file_header
->set_section_info(this->section_headers_
, shstrtab_section
);
2433 // Now we know exactly where everything goes in the output file
2434 // (except for non-allocated sections which require postprocessing).
2435 Output_data::layout_complete();
2437 this->output_file_size_
= off
;
2442 // Create a note header following the format defined in the ELF ABI.
2443 // NAME is the name, NOTE_TYPE is the type, SECTION_NAME is the name
2444 // of the section to create, DESCSZ is the size of the descriptor.
2445 // ALLOCATE is true if the section should be allocated in memory.
2446 // This returns the new note section. It sets *TRAILING_PADDING to
2447 // the number of trailing zero bytes required.
2450 Layout::create_note(const char* name
, int note_type
,
2451 const char* section_name
, size_t descsz
,
2452 bool allocate
, size_t* trailing_padding
)
2454 // Authorities all agree that the values in a .note field should
2455 // be aligned on 4-byte boundaries for 32-bit binaries. However,
2456 // they differ on what the alignment is for 64-bit binaries.
2457 // The GABI says unambiguously they take 8-byte alignment:
2458 // http://sco.com/developers/gabi/latest/ch5.pheader.html#note_section
2459 // Other documentation says alignment should always be 4 bytes:
2460 // http://www.netbsd.org/docs/kernel/elf-notes.html#note-format
2461 // GNU ld and GNU readelf both support the latter (at least as of
2462 // version 2.16.91), and glibc always generates the latter for
2463 // .note.ABI-tag (as of version 1.6), so that's the one we go with
2465 #ifdef GABI_FORMAT_FOR_DOTNOTE_SECTION // This is not defined by default.
2466 const int size
= parameters
->target().get_size();
2468 const int size
= 32;
2471 // The contents of the .note section.
2472 size_t namesz
= strlen(name
) + 1;
2473 size_t aligned_namesz
= align_address(namesz
, size
/ 8);
2474 size_t aligned_descsz
= align_address(descsz
, size
/ 8);
2476 size_t notehdrsz
= 3 * (size
/ 8) + aligned_namesz
;
2478 unsigned char* buffer
= new unsigned char[notehdrsz
];
2479 memset(buffer
, 0, notehdrsz
);
2481 bool is_big_endian
= parameters
->target().is_big_endian();
2487 elfcpp::Swap
<32, false>::writeval(buffer
, namesz
);
2488 elfcpp::Swap
<32, false>::writeval(buffer
+ 4, descsz
);
2489 elfcpp::Swap
<32, false>::writeval(buffer
+ 8, note_type
);
2493 elfcpp::Swap
<32, true>::writeval(buffer
, namesz
);
2494 elfcpp::Swap
<32, true>::writeval(buffer
+ 4, descsz
);
2495 elfcpp::Swap
<32, true>::writeval(buffer
+ 8, note_type
);
2498 else if (size
== 64)
2502 elfcpp::Swap
<64, false>::writeval(buffer
, namesz
);
2503 elfcpp::Swap
<64, false>::writeval(buffer
+ 8, descsz
);
2504 elfcpp::Swap
<64, false>::writeval(buffer
+ 16, note_type
);
2508 elfcpp::Swap
<64, true>::writeval(buffer
, namesz
);
2509 elfcpp::Swap
<64, true>::writeval(buffer
+ 8, descsz
);
2510 elfcpp::Swap
<64, true>::writeval(buffer
+ 16, note_type
);
2516 memcpy(buffer
+ 3 * (size
/ 8), name
, namesz
);
2518 elfcpp::Elf_Xword flags
= 0;
2519 Output_section_order order
= ORDER_INVALID
;
2522 flags
= elfcpp::SHF_ALLOC
;
2523 order
= ORDER_RO_NOTE
;
2525 Output_section
* os
= this->choose_output_section(NULL
, section_name
,
2527 flags
, false, order
, false);
2531 Output_section_data
* posd
= new Output_data_const_buffer(buffer
, notehdrsz
,
2534 os
->add_output_section_data(posd
);
2536 *trailing_padding
= aligned_descsz
- descsz
;
2541 // For an executable or shared library, create a note to record the
2542 // version of gold used to create the binary.
2545 Layout::create_gold_note()
2547 if (parameters
->options().relocatable()
2548 || parameters
->incremental_update())
2551 std::string desc
= std::string("gold ") + gold::get_version_string();
2553 size_t trailing_padding
;
2554 Output_section
* os
= this->create_note("GNU", elfcpp::NT_GNU_GOLD_VERSION
,
2555 ".note.gnu.gold-version", desc
.size(),
2556 false, &trailing_padding
);
2560 Output_section_data
* posd
= new Output_data_const(desc
, 4);
2561 os
->add_output_section_data(posd
);
2563 if (trailing_padding
> 0)
2565 posd
= new Output_data_zero_fill(trailing_padding
, 0);
2566 os
->add_output_section_data(posd
);
2570 // Record whether the stack should be executable. This can be set
2571 // from the command line using the -z execstack or -z noexecstack
2572 // options. Otherwise, if any input file has a .note.GNU-stack
2573 // section with the SHF_EXECINSTR flag set, the stack should be
2574 // executable. Otherwise, if at least one input file a
2575 // .note.GNU-stack section, and some input file has no .note.GNU-stack
2576 // section, we use the target default for whether the stack should be
2577 // executable. Otherwise, we don't generate a stack note. When
2578 // generating a object file, we create a .note.GNU-stack section with
2579 // the appropriate marking. When generating an executable or shared
2580 // library, we create a PT_GNU_STACK segment.
2583 Layout::create_executable_stack_info()
2585 bool is_stack_executable
;
2586 if (parameters
->options().is_execstack_set())
2587 is_stack_executable
= parameters
->options().is_stack_executable();
2588 else if (!this->input_with_gnu_stack_note_
)
2592 if (this->input_requires_executable_stack_
)
2593 is_stack_executable
= true;
2594 else if (this->input_without_gnu_stack_note_
)
2595 is_stack_executable
=
2596 parameters
->target().is_default_stack_executable();
2598 is_stack_executable
= false;
2601 if (parameters
->options().relocatable())
2603 const char* name
= this->namepool_
.add(".note.GNU-stack", false, NULL
);
2604 elfcpp::Elf_Xword flags
= 0;
2605 if (is_stack_executable
)
2606 flags
|= elfcpp::SHF_EXECINSTR
;
2607 this->make_output_section(name
, elfcpp::SHT_PROGBITS
, flags
,
2608 ORDER_INVALID
, false);
2612 if (this->script_options_
->saw_phdrs_clause())
2614 int flags
= elfcpp::PF_R
| elfcpp::PF_W
;
2615 if (is_stack_executable
)
2616 flags
|= elfcpp::PF_X
;
2617 this->make_output_segment(elfcpp::PT_GNU_STACK
, flags
);
2621 // If --build-id was used, set up the build ID note.
2624 Layout::create_build_id()
2626 if (!parameters
->options().user_set_build_id())
2629 const char* style
= parameters
->options().build_id();
2630 if (strcmp(style
, "none") == 0)
2633 // Set DESCSZ to the size of the note descriptor. When possible,
2634 // set DESC to the note descriptor contents.
2637 if (strcmp(style
, "md5") == 0)
2639 else if (strcmp(style
, "sha1") == 0)
2641 else if (strcmp(style
, "uuid") == 0)
2643 const size_t uuidsz
= 128 / 8;
2645 char buffer
[uuidsz
];
2646 memset(buffer
, 0, uuidsz
);
2648 int descriptor
= open_descriptor(-1, "/dev/urandom", O_RDONLY
);
2650 gold_error(_("--build-id=uuid failed: could not open /dev/urandom: %s"),
2654 ssize_t got
= ::read(descriptor
, buffer
, uuidsz
);
2655 release_descriptor(descriptor
, true);
2657 gold_error(_("/dev/urandom: read failed: %s"), strerror(errno
));
2658 else if (static_cast<size_t>(got
) != uuidsz
)
2659 gold_error(_("/dev/urandom: expected %zu bytes, got %zd bytes"),
2663 desc
.assign(buffer
, uuidsz
);
2666 else if (strncmp(style
, "0x", 2) == 0)
2669 const char* p
= style
+ 2;
2672 if (hex_p(p
[0]) && hex_p(p
[1]))
2674 char c
= (hex_value(p
[0]) << 4) | hex_value(p
[1]);
2678 else if (*p
== '-' || *p
== ':')
2681 gold_fatal(_("--build-id argument '%s' not a valid hex number"),
2684 descsz
= desc
.size();
2687 gold_fatal(_("unrecognized --build-id argument '%s'"), style
);
2690 size_t trailing_padding
;
2691 Output_section
* os
= this->create_note("GNU", elfcpp::NT_GNU_BUILD_ID
,
2692 ".note.gnu.build-id", descsz
, true,
2699 // We know the value already, so we fill it in now.
2700 gold_assert(desc
.size() == descsz
);
2702 Output_section_data
* posd
= new Output_data_const(desc
, 4);
2703 os
->add_output_section_data(posd
);
2705 if (trailing_padding
!= 0)
2707 posd
= new Output_data_zero_fill(trailing_padding
, 0);
2708 os
->add_output_section_data(posd
);
2713 // We need to compute a checksum after we have completed the
2715 gold_assert(trailing_padding
== 0);
2716 this->build_id_note_
= new Output_data_zero_fill(descsz
, 4);
2717 os
->add_output_section_data(this->build_id_note_
);
2721 // If we have both .stabXX and .stabXXstr sections, then the sh_link
2722 // field of the former should point to the latter. I'm not sure who
2723 // started this, but the GNU linker does it, and some tools depend
2727 Layout::link_stabs_sections()
2729 if (!this->have_stabstr_section_
)
2732 for (Section_list::iterator p
= this->section_list_
.begin();
2733 p
!= this->section_list_
.end();
2736 if ((*p
)->type() != elfcpp::SHT_STRTAB
)
2739 const char* name
= (*p
)->name();
2740 if (strncmp(name
, ".stab", 5) != 0)
2743 size_t len
= strlen(name
);
2744 if (strcmp(name
+ len
- 3, "str") != 0)
2747 std::string
stab_name(name
, len
- 3);
2748 Output_section
* stab_sec
;
2749 stab_sec
= this->find_output_section(stab_name
.c_str());
2750 if (stab_sec
!= NULL
)
2751 stab_sec
->set_link_section(*p
);
2755 // Create .gnu_incremental_inputs and related sections needed
2756 // for the next run of incremental linking to check what has changed.
2759 Layout::create_incremental_info_sections(Symbol_table
* symtab
)
2761 Incremental_inputs
* incr
= this->incremental_inputs_
;
2763 gold_assert(incr
!= NULL
);
2765 // Create the .gnu_incremental_inputs, _symtab, and _relocs input sections.
2766 incr
->create_data_sections(symtab
);
2768 // Add the .gnu_incremental_inputs section.
2769 const char* incremental_inputs_name
=
2770 this->namepool_
.add(".gnu_incremental_inputs", false, NULL
);
2771 Output_section
* incremental_inputs_os
=
2772 this->make_output_section(incremental_inputs_name
,
2773 elfcpp::SHT_GNU_INCREMENTAL_INPUTS
, 0,
2774 ORDER_INVALID
, false);
2775 incremental_inputs_os
->add_output_section_data(incr
->inputs_section());
2777 // Add the .gnu_incremental_symtab section.
2778 const char* incremental_symtab_name
=
2779 this->namepool_
.add(".gnu_incremental_symtab", false, NULL
);
2780 Output_section
* incremental_symtab_os
=
2781 this->make_output_section(incremental_symtab_name
,
2782 elfcpp::SHT_GNU_INCREMENTAL_SYMTAB
, 0,
2783 ORDER_INVALID
, false);
2784 incremental_symtab_os
->add_output_section_data(incr
->symtab_section());
2785 incremental_symtab_os
->set_entsize(4);
2787 // Add the .gnu_incremental_relocs section.
2788 const char* incremental_relocs_name
=
2789 this->namepool_
.add(".gnu_incremental_relocs", false, NULL
);
2790 Output_section
* incremental_relocs_os
=
2791 this->make_output_section(incremental_relocs_name
,
2792 elfcpp::SHT_GNU_INCREMENTAL_RELOCS
, 0,
2793 ORDER_INVALID
, false);
2794 incremental_relocs_os
->add_output_section_data(incr
->relocs_section());
2795 incremental_relocs_os
->set_entsize(incr
->relocs_entsize());
2797 // Add the .gnu_incremental_got_plt section.
2798 const char* incremental_got_plt_name
=
2799 this->namepool_
.add(".gnu_incremental_got_plt", false, NULL
);
2800 Output_section
* incremental_got_plt_os
=
2801 this->make_output_section(incremental_got_plt_name
,
2802 elfcpp::SHT_GNU_INCREMENTAL_GOT_PLT
, 0,
2803 ORDER_INVALID
, false);
2804 incremental_got_plt_os
->add_output_section_data(incr
->got_plt_section());
2806 // Add the .gnu_incremental_strtab section.
2807 const char* incremental_strtab_name
=
2808 this->namepool_
.add(".gnu_incremental_strtab", false, NULL
);
2809 Output_section
* incremental_strtab_os
= this->make_output_section(incremental_strtab_name
,
2810 elfcpp::SHT_STRTAB
, 0,
2811 ORDER_INVALID
, false);
2812 Output_data_strtab
* strtab_data
=
2813 new Output_data_strtab(incr
->get_stringpool());
2814 incremental_strtab_os
->add_output_section_data(strtab_data
);
2816 incremental_inputs_os
->set_after_input_sections();
2817 incremental_symtab_os
->set_after_input_sections();
2818 incremental_relocs_os
->set_after_input_sections();
2819 incremental_got_plt_os
->set_after_input_sections();
2821 incremental_inputs_os
->set_link_section(incremental_strtab_os
);
2822 incremental_symtab_os
->set_link_section(incremental_inputs_os
);
2823 incremental_relocs_os
->set_link_section(incremental_inputs_os
);
2824 incremental_got_plt_os
->set_link_section(incremental_inputs_os
);
2827 // Return whether SEG1 should be before SEG2 in the output file. This
2828 // is based entirely on the segment type and flags. When this is
2829 // called the segment addresses have normally not yet been set.
2832 Layout::segment_precedes(const Output_segment
* seg1
,
2833 const Output_segment
* seg2
)
2835 elfcpp::Elf_Word type1
= seg1
->type();
2836 elfcpp::Elf_Word type2
= seg2
->type();
2838 // The single PT_PHDR segment is required to precede any loadable
2839 // segment. We simply make it always first.
2840 if (type1
== elfcpp::PT_PHDR
)
2842 gold_assert(type2
!= elfcpp::PT_PHDR
);
2845 if (type2
== elfcpp::PT_PHDR
)
2848 // The single PT_INTERP segment is required to precede any loadable
2849 // segment. We simply make it always second.
2850 if (type1
== elfcpp::PT_INTERP
)
2852 gold_assert(type2
!= elfcpp::PT_INTERP
);
2855 if (type2
== elfcpp::PT_INTERP
)
2858 // We then put PT_LOAD segments before any other segments.
2859 if (type1
== elfcpp::PT_LOAD
&& type2
!= elfcpp::PT_LOAD
)
2861 if (type2
== elfcpp::PT_LOAD
&& type1
!= elfcpp::PT_LOAD
)
2864 // We put the PT_TLS segment last except for the PT_GNU_RELRO
2865 // segment, because that is where the dynamic linker expects to find
2866 // it (this is just for efficiency; other positions would also work
2868 if (type1
== elfcpp::PT_TLS
2869 && type2
!= elfcpp::PT_TLS
2870 && type2
!= elfcpp::PT_GNU_RELRO
)
2872 if (type2
== elfcpp::PT_TLS
2873 && type1
!= elfcpp::PT_TLS
2874 && type1
!= elfcpp::PT_GNU_RELRO
)
2877 // We put the PT_GNU_RELRO segment last, because that is where the
2878 // dynamic linker expects to find it (as with PT_TLS, this is just
2880 if (type1
== elfcpp::PT_GNU_RELRO
&& type2
!= elfcpp::PT_GNU_RELRO
)
2882 if (type2
== elfcpp::PT_GNU_RELRO
&& type1
!= elfcpp::PT_GNU_RELRO
)
2885 const elfcpp::Elf_Word flags1
= seg1
->flags();
2886 const elfcpp::Elf_Word flags2
= seg2
->flags();
2888 // The order of non-PT_LOAD segments is unimportant. We simply sort
2889 // by the numeric segment type and flags values. There should not
2890 // be more than one segment with the same type and flags.
2891 if (type1
!= elfcpp::PT_LOAD
)
2894 return type1
< type2
;
2895 gold_assert(flags1
!= flags2
);
2896 return flags1
< flags2
;
2899 // If the addresses are set already, sort by load address.
2900 if (seg1
->are_addresses_set())
2902 if (!seg2
->are_addresses_set())
2905 unsigned int section_count1
= seg1
->output_section_count();
2906 unsigned int section_count2
= seg2
->output_section_count();
2907 if (section_count1
== 0 && section_count2
> 0)
2909 if (section_count1
> 0 && section_count2
== 0)
2912 uint64_t paddr1
= (seg1
->are_addresses_set()
2914 : seg1
->first_section_load_address());
2915 uint64_t paddr2
= (seg2
->are_addresses_set()
2917 : seg2
->first_section_load_address());
2919 if (paddr1
!= paddr2
)
2920 return paddr1
< paddr2
;
2922 else if (seg2
->are_addresses_set())
2925 // A segment which holds large data comes after a segment which does
2926 // not hold large data.
2927 if (seg1
->is_large_data_segment())
2929 if (!seg2
->is_large_data_segment())
2932 else if (seg2
->is_large_data_segment())
2935 // Otherwise, we sort PT_LOAD segments based on the flags. Readonly
2936 // segments come before writable segments. Then writable segments
2937 // with data come before writable segments without data. Then
2938 // executable segments come before non-executable segments. Then
2939 // the unlikely case of a non-readable segment comes before the
2940 // normal case of a readable segment. If there are multiple
2941 // segments with the same type and flags, we require that the
2942 // address be set, and we sort by virtual address and then physical
2944 if ((flags1
& elfcpp::PF_W
) != (flags2
& elfcpp::PF_W
))
2945 return (flags1
& elfcpp::PF_W
) == 0;
2946 if ((flags1
& elfcpp::PF_W
) != 0
2947 && seg1
->has_any_data_sections() != seg2
->has_any_data_sections())
2948 return seg1
->has_any_data_sections();
2949 if ((flags1
& elfcpp::PF_X
) != (flags2
& elfcpp::PF_X
))
2950 return (flags1
& elfcpp::PF_X
) != 0;
2951 if ((flags1
& elfcpp::PF_R
) != (flags2
& elfcpp::PF_R
))
2952 return (flags1
& elfcpp::PF_R
) == 0;
2954 // We shouldn't get here--we shouldn't create segments which we
2955 // can't distinguish. Unless of course we are using a weird linker
2957 gold_assert(this->script_options_
->saw_phdrs_clause());
2961 // Increase OFF so that it is congruent to ADDR modulo ABI_PAGESIZE.
2964 align_file_offset(off_t off
, uint64_t addr
, uint64_t abi_pagesize
)
2966 uint64_t unsigned_off
= off
;
2967 uint64_t aligned_off
= ((unsigned_off
& ~(abi_pagesize
- 1))
2968 | (addr
& (abi_pagesize
- 1)));
2969 if (aligned_off
< unsigned_off
)
2970 aligned_off
+= abi_pagesize
;
2974 // Set the file offsets of all the segments, and all the sections they
2975 // contain. They have all been created. LOAD_SEG must be be laid out
2976 // first. Return the offset of the data to follow.
2979 Layout::set_segment_offsets(const Target
* target
, Output_segment
* load_seg
,
2980 unsigned int* pshndx
)
2982 // Sort them into the final order. We use a stable sort so that we
2983 // don't randomize the order of indistinguishable segments created
2984 // by linker scripts.
2985 std::stable_sort(this->segment_list_
.begin(), this->segment_list_
.end(),
2986 Layout::Compare_segments(this));
2988 // Find the PT_LOAD segments, and set their addresses and offsets
2989 // and their section's addresses and offsets.
2991 if (parameters
->options().user_set_Ttext())
2992 addr
= parameters
->options().Ttext();
2993 else if (parameters
->options().output_is_position_independent())
2996 addr
= target
->default_text_segment_address();
2999 // If LOAD_SEG is NULL, then the file header and segment headers
3000 // will not be loadable. But they still need to be at offset 0 in
3001 // the file. Set their offsets now.
3002 if (load_seg
== NULL
)
3004 for (Data_list::iterator p
= this->special_output_list_
.begin();
3005 p
!= this->special_output_list_
.end();
3008 off
= align_address(off
, (*p
)->addralign());
3009 (*p
)->set_address_and_file_offset(0, off
);
3010 off
+= (*p
)->data_size();
3014 unsigned int increase_relro
= this->increase_relro_
;
3015 if (this->script_options_
->saw_sections_clause())
3018 const bool check_sections
= parameters
->options().check_sections();
3019 Output_segment
* last_load_segment
= NULL
;
3021 for (Segment_list::iterator p
= this->segment_list_
.begin();
3022 p
!= this->segment_list_
.end();
3025 if ((*p
)->type() == elfcpp::PT_LOAD
)
3027 if (load_seg
!= NULL
&& load_seg
!= *p
)
3031 bool are_addresses_set
= (*p
)->are_addresses_set();
3032 if (are_addresses_set
)
3034 // When it comes to setting file offsets, we care about
3035 // the physical address.
3036 addr
= (*p
)->paddr();
3038 else if (parameters
->options().user_set_Tdata()
3039 && ((*p
)->flags() & elfcpp::PF_W
) != 0
3040 && (!parameters
->options().user_set_Tbss()
3041 || (*p
)->has_any_data_sections()))
3043 addr
= parameters
->options().Tdata();
3044 are_addresses_set
= true;
3046 else if (parameters
->options().user_set_Tbss()
3047 && ((*p
)->flags() & elfcpp::PF_W
) != 0
3048 && !(*p
)->has_any_data_sections())
3050 addr
= parameters
->options().Tbss();
3051 are_addresses_set
= true;
3054 uint64_t orig_addr
= addr
;
3055 uint64_t orig_off
= off
;
3057 uint64_t aligned_addr
= 0;
3058 uint64_t abi_pagesize
= target
->abi_pagesize();
3059 uint64_t common_pagesize
= target
->common_pagesize();
3061 if (!parameters
->options().nmagic()
3062 && !parameters
->options().omagic())
3063 (*p
)->set_minimum_p_align(common_pagesize
);
3065 if (!are_addresses_set
)
3067 // Skip the address forward one page, maintaining the same
3068 // position within the page. This lets us store both segments
3069 // overlapping on a single page in the file, but the loader will
3070 // put them on different pages in memory. We will revisit this
3071 // decision once we know the size of the segment.
3073 addr
= align_address(addr
, (*p
)->maximum_alignment());
3074 aligned_addr
= addr
;
3076 if ((addr
& (abi_pagesize
- 1)) != 0)
3077 addr
= addr
+ abi_pagesize
;
3079 off
= orig_off
+ ((addr
- orig_addr
) & (abi_pagesize
- 1));
3082 if (!parameters
->options().nmagic()
3083 && !parameters
->options().omagic())
3084 off
= align_file_offset(off
, addr
, abi_pagesize
);
3085 else if (load_seg
== NULL
)
3087 // This is -N or -n with a section script which prevents
3088 // us from using a load segment. We need to ensure that
3089 // the file offset is aligned to the alignment of the
3090 // segment. This is because the linker script
3091 // implicitly assumed a zero offset. If we don't align
3092 // here, then the alignment of the sections in the
3093 // linker script may not match the alignment of the
3094 // sections in the set_section_addresses call below,
3095 // causing an error about dot moving backward.
3096 off
= align_address(off
, (*p
)->maximum_alignment());
3099 unsigned int shndx_hold
= *pshndx
;
3100 bool has_relro
= false;
3101 uint64_t new_addr
= (*p
)->set_section_addresses(this, false, addr
,
3106 // Now that we know the size of this segment, we may be able
3107 // to save a page in memory, at the cost of wasting some
3108 // file space, by instead aligning to the start of a new
3109 // page. Here we use the real machine page size rather than
3110 // the ABI mandated page size. If the segment has been
3111 // aligned so that the relro data ends at a page boundary,
3112 // we do not try to realign it.
3114 if (!are_addresses_set
3116 && aligned_addr
!= addr
3117 && !parameters
->incremental())
3119 uint64_t first_off
= (common_pagesize
3121 & (common_pagesize
- 1)));
3122 uint64_t last_off
= new_addr
& (common_pagesize
- 1);
3125 && ((aligned_addr
& ~ (common_pagesize
- 1))
3126 != (new_addr
& ~ (common_pagesize
- 1)))
3127 && first_off
+ last_off
<= common_pagesize
)
3129 *pshndx
= shndx_hold
;
3130 addr
= align_address(aligned_addr
, common_pagesize
);
3131 addr
= align_address(addr
, (*p
)->maximum_alignment());
3132 off
= orig_off
+ ((addr
- orig_addr
) & (abi_pagesize
- 1));
3133 off
= align_file_offset(off
, addr
, abi_pagesize
);
3135 increase_relro
= this->increase_relro_
;
3136 if (this->script_options_
->saw_sections_clause())
3140 new_addr
= (*p
)->set_section_addresses(this, true, addr
,
3149 // Implement --check-sections. We know that the segments
3150 // are sorted by LMA.
3151 if (check_sections
&& last_load_segment
!= NULL
)
3153 gold_assert(last_load_segment
->paddr() <= (*p
)->paddr());
3154 if (last_load_segment
->paddr() + last_load_segment
->memsz()
3157 unsigned long long lb1
= last_load_segment
->paddr();
3158 unsigned long long le1
= lb1
+ last_load_segment
->memsz();
3159 unsigned long long lb2
= (*p
)->paddr();
3160 unsigned long long le2
= lb2
+ (*p
)->memsz();
3161 gold_error(_("load segment overlap [0x%llx -> 0x%llx] and "
3162 "[0x%llx -> 0x%llx]"),
3163 lb1
, le1
, lb2
, le2
);
3166 last_load_segment
= *p
;
3170 // Handle the non-PT_LOAD segments, setting their offsets from their
3171 // section's offsets.
3172 for (Segment_list::iterator p
= this->segment_list_
.begin();
3173 p
!= this->segment_list_
.end();
3176 if ((*p
)->type() != elfcpp::PT_LOAD
)
3177 (*p
)->set_offset((*p
)->type() == elfcpp::PT_GNU_RELRO
3182 // Set the TLS offsets for each section in the PT_TLS segment.
3183 if (this->tls_segment_
!= NULL
)
3184 this->tls_segment_
->set_tls_offsets();
3189 // Set the offsets of all the allocated sections when doing a
3190 // relocatable link. This does the same jobs as set_segment_offsets,
3191 // only for a relocatable link.
3194 Layout::set_relocatable_section_offsets(Output_data
* file_header
,
3195 unsigned int* pshndx
)
3199 file_header
->set_address_and_file_offset(0, 0);
3200 off
+= file_header
->data_size();
3202 for (Section_list::iterator p
= this->section_list_
.begin();
3203 p
!= this->section_list_
.end();
3206 // We skip unallocated sections here, except that group sections
3207 // have to come first.
3208 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) == 0
3209 && (*p
)->type() != elfcpp::SHT_GROUP
)
3212 off
= align_address(off
, (*p
)->addralign());
3214 // The linker script might have set the address.
3215 if (!(*p
)->is_address_valid())
3216 (*p
)->set_address(0);
3217 (*p
)->set_file_offset(off
);
3218 (*p
)->finalize_data_size();
3219 off
+= (*p
)->data_size();
3221 (*p
)->set_out_shndx(*pshndx
);
3228 // Set the file offset of all the sections not associated with a
3232 Layout::set_section_offsets(off_t off
, Layout::Section_offset_pass pass
)
3234 off_t startoff
= off
;
3237 for (Section_list::iterator p
= this->unattached_section_list_
.begin();
3238 p
!= this->unattached_section_list_
.end();
3241 // The symtab section is handled in create_symtab_sections.
3242 if (*p
== this->symtab_section_
)
3245 // If we've already set the data size, don't set it again.
3246 if ((*p
)->is_offset_valid() && (*p
)->is_data_size_valid())
3249 if (pass
== BEFORE_INPUT_SECTIONS_PASS
3250 && (*p
)->requires_postprocessing())
3252 (*p
)->create_postprocessing_buffer();
3253 this->any_postprocessing_sections_
= true;
3256 if (pass
== BEFORE_INPUT_SECTIONS_PASS
3257 && (*p
)->after_input_sections())
3259 else if (pass
== POSTPROCESSING_SECTIONS_PASS
3260 && (!(*p
)->after_input_sections()
3261 || (*p
)->type() == elfcpp::SHT_STRTAB
))
3263 else if (pass
== STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
3264 && (!(*p
)->after_input_sections()
3265 || (*p
)->type() != elfcpp::SHT_STRTAB
))
3268 if (!parameters
->incremental_update())
3270 off
= align_address(off
, (*p
)->addralign());
3271 (*p
)->set_file_offset(off
);
3272 (*p
)->finalize_data_size();
3276 // Incremental update: allocate file space from free list.
3277 (*p
)->pre_finalize_data_size();
3278 off_t current_size
= (*p
)->current_data_size();
3279 off
= this->allocate(current_size
, (*p
)->addralign(), startoff
);
3282 if (is_debugging_enabled(DEBUG_INCREMENTAL
))
3283 this->free_list_
.dump();
3284 gold_assert((*p
)->output_section() != NULL
);
3285 gold_fallback(_("out of patch space for section %s; "
3286 "relink with --incremental-full"),
3287 (*p
)->output_section()->name());
3289 (*p
)->set_file_offset(off
);
3290 (*p
)->finalize_data_size();
3291 if ((*p
)->data_size() > current_size
)
3293 gold_assert((*p
)->output_section() != NULL
);
3294 gold_fallback(_("%s: section changed size; "
3295 "relink with --incremental-full"),
3296 (*p
)->output_section()->name());
3298 gold_debug(DEBUG_INCREMENTAL
,
3299 "set_section_offsets: %08lx %08lx %s",
3300 static_cast<long>(off
),
3301 static_cast<long>((*p
)->data_size()),
3302 ((*p
)->output_section() != NULL
3303 ? (*p
)->output_section()->name() : "(special)"));
3306 off
+= (*p
)->data_size();
3310 // At this point the name must be set.
3311 if (pass
!= STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
)
3312 this->namepool_
.add((*p
)->name(), false, NULL
);
3317 // Set the section indexes of all the sections not associated with a
3321 Layout::set_section_indexes(unsigned int shndx
)
3323 for (Section_list::iterator p
= this->unattached_section_list_
.begin();
3324 p
!= this->unattached_section_list_
.end();
3327 if (!(*p
)->has_out_shndx())
3329 (*p
)->set_out_shndx(shndx
);
3336 // Set the section addresses according to the linker script. This is
3337 // only called when we see a SECTIONS clause. This returns the
3338 // program segment which should hold the file header and segment
3339 // headers, if any. It will return NULL if they should not be in a
3343 Layout::set_section_addresses_from_script(Symbol_table
* symtab
)
3345 Script_sections
* ss
= this->script_options_
->script_sections();
3346 gold_assert(ss
->saw_sections_clause());
3347 return this->script_options_
->set_section_addresses(symtab
, this);
3350 // Place the orphan sections in the linker script.
3353 Layout::place_orphan_sections_in_script()
3355 Script_sections
* ss
= this->script_options_
->script_sections();
3356 gold_assert(ss
->saw_sections_clause());
3358 // Place each orphaned output section in the script.
3359 for (Section_list::iterator p
= this->section_list_
.begin();
3360 p
!= this->section_list_
.end();
3363 if (!(*p
)->found_in_sections_clause())
3364 ss
->place_orphan(*p
);
3368 // Count the local symbols in the regular symbol table and the dynamic
3369 // symbol table, and build the respective string pools.
3372 Layout::count_local_symbols(const Task
* task
,
3373 const Input_objects
* input_objects
)
3375 // First, figure out an upper bound on the number of symbols we'll
3376 // be inserting into each pool. This helps us create the pools with
3377 // the right size, to avoid unnecessary hashtable resizing.
3378 unsigned int symbol_count
= 0;
3379 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
3380 p
!= input_objects
->relobj_end();
3382 symbol_count
+= (*p
)->local_symbol_count();
3384 // Go from "upper bound" to "estimate." We overcount for two
3385 // reasons: we double-count symbols that occur in more than one
3386 // object file, and we count symbols that are dropped from the
3387 // output. Add it all together and assume we overcount by 100%.
3390 // We assume all symbols will go into both the sympool and dynpool.
3391 this->sympool_
.reserve(symbol_count
);
3392 this->dynpool_
.reserve(symbol_count
);
3394 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
3395 p
!= input_objects
->relobj_end();
3398 Task_lock_obj
<Object
> tlo(task
, *p
);
3399 (*p
)->count_local_symbols(&this->sympool_
, &this->dynpool_
);
3403 // Create the symbol table sections. Here we also set the final
3404 // values of the symbols. At this point all the loadable sections are
3405 // fully laid out. SHNUM is the number of sections so far.
3408 Layout::create_symtab_sections(const Input_objects
* input_objects
,
3409 Symbol_table
* symtab
,
3415 if (parameters
->target().get_size() == 32)
3417 symsize
= elfcpp::Elf_sizes
<32>::sym_size
;
3420 else if (parameters
->target().get_size() == 64)
3422 symsize
= elfcpp::Elf_sizes
<64>::sym_size
;
3428 // Compute file offsets relative to the start of the symtab section.
3431 // Save space for the dummy symbol at the start of the section. We
3432 // never bother to write this out--it will just be left as zero.
3434 unsigned int local_symbol_index
= 1;
3436 // Add STT_SECTION symbols for each Output section which needs one.
3437 for (Section_list::iterator p
= this->section_list_
.begin();
3438 p
!= this->section_list_
.end();
3441 if (!(*p
)->needs_symtab_index())
3442 (*p
)->set_symtab_index(-1U);
3445 (*p
)->set_symtab_index(local_symbol_index
);
3446 ++local_symbol_index
;
3451 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
3452 p
!= input_objects
->relobj_end();
3455 unsigned int index
= (*p
)->finalize_local_symbols(local_symbol_index
,
3457 off
+= (index
- local_symbol_index
) * symsize
;
3458 local_symbol_index
= index
;
3461 unsigned int local_symcount
= local_symbol_index
;
3462 gold_assert(static_cast<off_t
>(local_symcount
* symsize
) == off
);
3465 size_t dyn_global_index
;
3467 if (this->dynsym_section_
== NULL
)
3470 dyn_global_index
= 0;
3475 dyn_global_index
= this->dynsym_section_
->info();
3476 off_t locsize
= dyn_global_index
* this->dynsym_section_
->entsize();
3477 dynoff
= this->dynsym_section_
->offset() + locsize
;
3478 dyncount
= (this->dynsym_section_
->data_size() - locsize
) / symsize
;
3479 gold_assert(static_cast<off_t
>(dyncount
* symsize
)
3480 == this->dynsym_section_
->data_size() - locsize
);
3483 off_t global_off
= off
;
3484 off
= symtab
->finalize(off
, dynoff
, dyn_global_index
, dyncount
,
3485 &this->sympool_
, &local_symcount
);
3487 if (!parameters
->options().strip_all())
3489 this->sympool_
.set_string_offsets();
3491 const char* symtab_name
= this->namepool_
.add(".symtab", false, NULL
);
3492 Output_section
* osymtab
= this->make_output_section(symtab_name
,
3496 this->symtab_section_
= osymtab
;
3498 Output_section_data
* pos
= new Output_data_fixed_space(off
, align
,
3500 osymtab
->add_output_section_data(pos
);
3502 // We generate a .symtab_shndx section if we have more than
3503 // SHN_LORESERVE sections. Technically it is possible that we
3504 // don't need one, because it is possible that there are no
3505 // symbols in any of sections with indexes larger than
3506 // SHN_LORESERVE. That is probably unusual, though, and it is
3507 // easier to always create one than to compute section indexes
3508 // twice (once here, once when writing out the symbols).
3509 if (shnum
>= elfcpp::SHN_LORESERVE
)
3511 const char* symtab_xindex_name
= this->namepool_
.add(".symtab_shndx",
3513 Output_section
* osymtab_xindex
=
3514 this->make_output_section(symtab_xindex_name
,
3515 elfcpp::SHT_SYMTAB_SHNDX
, 0,
3516 ORDER_INVALID
, false);
3518 size_t symcount
= off
/ symsize
;
3519 this->symtab_xindex_
= new Output_symtab_xindex(symcount
);
3521 osymtab_xindex
->add_output_section_data(this->symtab_xindex_
);
3523 osymtab_xindex
->set_link_section(osymtab
);
3524 osymtab_xindex
->set_addralign(4);
3525 osymtab_xindex
->set_entsize(4);
3527 osymtab_xindex
->set_after_input_sections();
3529 // This tells the driver code to wait until the symbol table
3530 // has written out before writing out the postprocessing
3531 // sections, including the .symtab_shndx section.
3532 this->any_postprocessing_sections_
= true;
3535 const char* strtab_name
= this->namepool_
.add(".strtab", false, NULL
);
3536 Output_section
* ostrtab
= this->make_output_section(strtab_name
,
3541 Output_section_data
* pstr
= new Output_data_strtab(&this->sympool_
);
3542 ostrtab
->add_output_section_data(pstr
);
3545 if (!parameters
->incremental_update())
3546 symtab_off
= align_address(*poff
, align
);
3549 symtab_off
= this->allocate(off
, align
, *poff
);
3551 gold_fallback(_("out of patch space for symbol table; "
3552 "relink with --incremental-full"));
3553 gold_debug(DEBUG_INCREMENTAL
,
3554 "create_symtab_sections: %08lx %08lx .symtab",
3555 static_cast<long>(symtab_off
),
3556 static_cast<long>(off
));
3559 symtab
->set_file_offset(symtab_off
+ global_off
);
3560 osymtab
->set_file_offset(symtab_off
);
3561 osymtab
->finalize_data_size();
3562 osymtab
->set_link_section(ostrtab
);
3563 osymtab
->set_info(local_symcount
);
3564 osymtab
->set_entsize(symsize
);
3566 if (symtab_off
+ off
> *poff
)
3567 *poff
= symtab_off
+ off
;
3571 // Create the .shstrtab section, which holds the names of the
3572 // sections. At the time this is called, we have created all the
3573 // output sections except .shstrtab itself.
3576 Layout::create_shstrtab()
3578 // FIXME: We don't need to create a .shstrtab section if we are
3579 // stripping everything.
3581 const char* name
= this->namepool_
.add(".shstrtab", false, NULL
);
3583 Output_section
* os
= this->make_output_section(name
, elfcpp::SHT_STRTAB
, 0,
3584 ORDER_INVALID
, false);
3586 if (strcmp(parameters
->options().compress_debug_sections(), "none") != 0)
3588 // We can't write out this section until we've set all the
3589 // section names, and we don't set the names of compressed
3590 // output sections until relocations are complete. FIXME: With
3591 // the current names we use, this is unnecessary.
3592 os
->set_after_input_sections();
3595 Output_section_data
* posd
= new Output_data_strtab(&this->namepool_
);
3596 os
->add_output_section_data(posd
);
3601 // Create the section headers. SIZE is 32 or 64. OFF is the file
3605 Layout::create_shdrs(const Output_section
* shstrtab_section
, off_t
* poff
)
3607 Output_section_headers
* oshdrs
;
3608 oshdrs
= new Output_section_headers(this,
3609 &this->segment_list_
,
3610 &this->section_list_
,
3611 &this->unattached_section_list_
,
3615 if (!parameters
->incremental_update())
3616 off
= align_address(*poff
, oshdrs
->addralign());
3619 oshdrs
->pre_finalize_data_size();
3620 off
= this->allocate(oshdrs
->data_size(), oshdrs
->addralign(), *poff
);
3622 gold_fallback(_("out of patch space for section header table; "
3623 "relink with --incremental-full"));
3624 gold_debug(DEBUG_INCREMENTAL
,
3625 "create_shdrs: %08lx %08lx (section header table)",
3626 static_cast<long>(off
),
3627 static_cast<long>(off
+ oshdrs
->data_size()));
3629 oshdrs
->set_address_and_file_offset(0, off
);
3630 off
+= oshdrs
->data_size();
3633 this->section_headers_
= oshdrs
;
3636 // Count the allocated sections.
3639 Layout::allocated_output_section_count() const
3641 size_t section_count
= 0;
3642 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
3643 p
!= this->segment_list_
.end();
3645 section_count
+= (*p
)->output_section_count();
3646 return section_count
;
3649 // Create the dynamic symbol table.
3652 Layout::create_dynamic_symtab(const Input_objects
* input_objects
,
3653 Symbol_table
* symtab
,
3654 Output_section
** pdynstr
,
3655 unsigned int* plocal_dynamic_count
,
3656 std::vector
<Symbol
*>* pdynamic_symbols
,
3657 Versions
* pversions
)
3659 // Count all the symbols in the dynamic symbol table, and set the
3660 // dynamic symbol indexes.
3662 // Skip symbol 0, which is always all zeroes.
3663 unsigned int index
= 1;
3665 // Add STT_SECTION symbols for each Output section which needs one.
3666 for (Section_list::iterator p
= this->section_list_
.begin();
3667 p
!= this->section_list_
.end();
3670 if (!(*p
)->needs_dynsym_index())
3671 (*p
)->set_dynsym_index(-1U);
3674 (*p
)->set_dynsym_index(index
);
3679 // Count the local symbols that need to go in the dynamic symbol table,
3680 // and set the dynamic symbol indexes.
3681 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
3682 p
!= input_objects
->relobj_end();
3685 unsigned int new_index
= (*p
)->set_local_dynsym_indexes(index
);
3689 unsigned int local_symcount
= index
;
3690 *plocal_dynamic_count
= local_symcount
;
3692 index
= symtab
->set_dynsym_indexes(index
, pdynamic_symbols
,
3693 &this->dynpool_
, pversions
);
3697 const int size
= parameters
->target().get_size();
3700 symsize
= elfcpp::Elf_sizes
<32>::sym_size
;
3703 else if (size
== 64)
3705 symsize
= elfcpp::Elf_sizes
<64>::sym_size
;
3711 // Create the dynamic symbol table section.
3713 Output_section
* dynsym
= this->choose_output_section(NULL
, ".dynsym",
3717 ORDER_DYNAMIC_LINKER
,
3720 // Check for NULL as a linker script may discard .dynsym.
3723 Output_section_data
* odata
= new Output_data_fixed_space(index
* symsize
,
3726 dynsym
->add_output_section_data(odata
);
3728 dynsym
->set_info(local_symcount
);
3729 dynsym
->set_entsize(symsize
);
3730 dynsym
->set_addralign(align
);
3732 this->dynsym_section_
= dynsym
;
3735 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
3738 odyn
->add_section_address(elfcpp::DT_SYMTAB
, dynsym
);
3739 odyn
->add_constant(elfcpp::DT_SYMENT
, symsize
);
3742 // If there are more than SHN_LORESERVE allocated sections, we
3743 // create a .dynsym_shndx section. It is possible that we don't
3744 // need one, because it is possible that there are no dynamic
3745 // symbols in any of the sections with indexes larger than
3746 // SHN_LORESERVE. This is probably unusual, though, and at this
3747 // time we don't know the actual section indexes so it is
3748 // inconvenient to check.
3749 if (this->allocated_output_section_count() >= elfcpp::SHN_LORESERVE
)
3751 Output_section
* dynsym_xindex
=
3752 this->choose_output_section(NULL
, ".dynsym_shndx",
3753 elfcpp::SHT_SYMTAB_SHNDX
,
3755 false, ORDER_DYNAMIC_LINKER
, false);
3757 if (dynsym_xindex
!= NULL
)
3759 this->dynsym_xindex_
= new Output_symtab_xindex(index
);
3761 dynsym_xindex
->add_output_section_data(this->dynsym_xindex_
);
3763 dynsym_xindex
->set_link_section(dynsym
);
3764 dynsym_xindex
->set_addralign(4);
3765 dynsym_xindex
->set_entsize(4);
3767 dynsym_xindex
->set_after_input_sections();
3769 // This tells the driver code to wait until the symbol table
3770 // has written out before writing out the postprocessing
3771 // sections, including the .dynsym_shndx section.
3772 this->any_postprocessing_sections_
= true;
3776 // Create the dynamic string table section.
3778 Output_section
* dynstr
= this->choose_output_section(NULL
, ".dynstr",
3782 ORDER_DYNAMIC_LINKER
,
3787 Output_section_data
* strdata
= new Output_data_strtab(&this->dynpool_
);
3788 dynstr
->add_output_section_data(strdata
);
3791 dynsym
->set_link_section(dynstr
);
3792 if (this->dynamic_section_
!= NULL
)
3793 this->dynamic_section_
->set_link_section(dynstr
);
3797 odyn
->add_section_address(elfcpp::DT_STRTAB
, dynstr
);
3798 odyn
->add_section_size(elfcpp::DT_STRSZ
, dynstr
);
3804 // Create the hash tables.
3806 if (strcmp(parameters
->options().hash_style(), "sysv") == 0
3807 || strcmp(parameters
->options().hash_style(), "both") == 0)
3809 unsigned char* phash
;
3810 unsigned int hashlen
;
3811 Dynobj::create_elf_hash_table(*pdynamic_symbols
, local_symcount
,
3814 Output_section
* hashsec
=
3815 this->choose_output_section(NULL
, ".hash", elfcpp::SHT_HASH
,
3816 elfcpp::SHF_ALLOC
, false,
3817 ORDER_DYNAMIC_LINKER
, false);
3819 Output_section_data
* hashdata
= new Output_data_const_buffer(phash
,
3823 if (hashsec
!= NULL
&& hashdata
!= NULL
)
3824 hashsec
->add_output_section_data(hashdata
);
3826 if (hashsec
!= NULL
)
3829 hashsec
->set_link_section(dynsym
);
3830 hashsec
->set_entsize(4);
3834 odyn
->add_section_address(elfcpp::DT_HASH
, hashsec
);
3837 if (strcmp(parameters
->options().hash_style(), "gnu") == 0
3838 || strcmp(parameters
->options().hash_style(), "both") == 0)
3840 unsigned char* phash
;
3841 unsigned int hashlen
;
3842 Dynobj::create_gnu_hash_table(*pdynamic_symbols
, local_symcount
,
3845 Output_section
* hashsec
=
3846 this->choose_output_section(NULL
, ".gnu.hash", elfcpp::SHT_GNU_HASH
,
3847 elfcpp::SHF_ALLOC
, false,
3848 ORDER_DYNAMIC_LINKER
, false);
3850 Output_section_data
* hashdata
= new Output_data_const_buffer(phash
,
3854 if (hashsec
!= NULL
&& hashdata
!= NULL
)
3855 hashsec
->add_output_section_data(hashdata
);
3857 if (hashsec
!= NULL
)
3860 hashsec
->set_link_section(dynsym
);
3862 // For a 64-bit target, the entries in .gnu.hash do not have
3863 // a uniform size, so we only set the entry size for a
3865 if (parameters
->target().get_size() == 32)
3866 hashsec
->set_entsize(4);
3869 odyn
->add_section_address(elfcpp::DT_GNU_HASH
, hashsec
);
3874 // Assign offsets to each local portion of the dynamic symbol table.
3877 Layout::assign_local_dynsym_offsets(const Input_objects
* input_objects
)
3879 Output_section
* dynsym
= this->dynsym_section_
;
3883 off_t off
= dynsym
->offset();
3885 // Skip the dummy symbol at the start of the section.
3886 off
+= dynsym
->entsize();
3888 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
3889 p
!= input_objects
->relobj_end();
3892 unsigned int count
= (*p
)->set_local_dynsym_offset(off
);
3893 off
+= count
* dynsym
->entsize();
3897 // Create the version sections.
3900 Layout::create_version_sections(const Versions
* versions
,
3901 const Symbol_table
* symtab
,
3902 unsigned int local_symcount
,
3903 const std::vector
<Symbol
*>& dynamic_symbols
,
3904 const Output_section
* dynstr
)
3906 if (!versions
->any_defs() && !versions
->any_needs())
3909 switch (parameters
->size_and_endianness())
3911 #ifdef HAVE_TARGET_32_LITTLE
3912 case Parameters::TARGET_32_LITTLE
:
3913 this->sized_create_version_sections
<32, false>(versions
, symtab
,
3915 dynamic_symbols
, dynstr
);
3918 #ifdef HAVE_TARGET_32_BIG
3919 case Parameters::TARGET_32_BIG
:
3920 this->sized_create_version_sections
<32, true>(versions
, symtab
,
3922 dynamic_symbols
, dynstr
);
3925 #ifdef HAVE_TARGET_64_LITTLE
3926 case Parameters::TARGET_64_LITTLE
:
3927 this->sized_create_version_sections
<64, false>(versions
, symtab
,
3929 dynamic_symbols
, dynstr
);
3932 #ifdef HAVE_TARGET_64_BIG
3933 case Parameters::TARGET_64_BIG
:
3934 this->sized_create_version_sections
<64, true>(versions
, symtab
,
3936 dynamic_symbols
, dynstr
);
3944 // Create the version sections, sized version.
3946 template<int size
, bool big_endian
>
3948 Layout::sized_create_version_sections(
3949 const Versions
* versions
,
3950 const Symbol_table
* symtab
,
3951 unsigned int local_symcount
,
3952 const std::vector
<Symbol
*>& dynamic_symbols
,
3953 const Output_section
* dynstr
)
3955 Output_section
* vsec
= this->choose_output_section(NULL
, ".gnu.version",
3956 elfcpp::SHT_GNU_versym
,
3959 ORDER_DYNAMIC_LINKER
,
3962 // Check for NULL since a linker script may discard this section.
3965 unsigned char* vbuf
;
3967 versions
->symbol_section_contents
<size
, big_endian
>(symtab
,
3973 Output_section_data
* vdata
= new Output_data_const_buffer(vbuf
, vsize
, 2,
3976 vsec
->add_output_section_data(vdata
);
3977 vsec
->set_entsize(2);
3978 vsec
->set_link_section(this->dynsym_section_
);
3981 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
3982 if (odyn
!= NULL
&& vsec
!= NULL
)
3983 odyn
->add_section_address(elfcpp::DT_VERSYM
, vsec
);
3985 if (versions
->any_defs())
3987 Output_section
* vdsec
;
3988 vdsec
= this->choose_output_section(NULL
, ".gnu.version_d",
3989 elfcpp::SHT_GNU_verdef
,
3991 false, ORDER_DYNAMIC_LINKER
, false);
3995 unsigned char* vdbuf
;
3996 unsigned int vdsize
;
3997 unsigned int vdentries
;
3998 versions
->def_section_contents
<size
, big_endian
>(&this->dynpool_
,
4002 Output_section_data
* vddata
=
4003 new Output_data_const_buffer(vdbuf
, vdsize
, 4, "** version defs");
4005 vdsec
->add_output_section_data(vddata
);
4006 vdsec
->set_link_section(dynstr
);
4007 vdsec
->set_info(vdentries
);
4011 odyn
->add_section_address(elfcpp::DT_VERDEF
, vdsec
);
4012 odyn
->add_constant(elfcpp::DT_VERDEFNUM
, vdentries
);
4017 if (versions
->any_needs())
4019 Output_section
* vnsec
;
4020 vnsec
= this->choose_output_section(NULL
, ".gnu.version_r",
4021 elfcpp::SHT_GNU_verneed
,
4023 false, ORDER_DYNAMIC_LINKER
, false);
4027 unsigned char* vnbuf
;
4028 unsigned int vnsize
;
4029 unsigned int vnentries
;
4030 versions
->need_section_contents
<size
, big_endian
>(&this->dynpool_
,
4034 Output_section_data
* vndata
=
4035 new Output_data_const_buffer(vnbuf
, vnsize
, 4, "** version refs");
4037 vnsec
->add_output_section_data(vndata
);
4038 vnsec
->set_link_section(dynstr
);
4039 vnsec
->set_info(vnentries
);
4043 odyn
->add_section_address(elfcpp::DT_VERNEED
, vnsec
);
4044 odyn
->add_constant(elfcpp::DT_VERNEEDNUM
, vnentries
);
4050 // Create the .interp section and PT_INTERP segment.
4053 Layout::create_interp(const Target
* target
)
4055 gold_assert(this->interp_segment_
== NULL
);
4057 const char* interp
= parameters
->options().dynamic_linker();
4060 interp
= target
->dynamic_linker();
4061 gold_assert(interp
!= NULL
);
4064 size_t len
= strlen(interp
) + 1;
4066 Output_section_data
* odata
= new Output_data_const(interp
, len
, 1);
4068 Output_section
* osec
= this->choose_output_section(NULL
, ".interp",
4069 elfcpp::SHT_PROGBITS
,
4071 false, ORDER_INTERP
,
4074 osec
->add_output_section_data(odata
);
4077 // Add dynamic tags for the PLT and the dynamic relocs. This is
4078 // called by the target-specific code. This does nothing if not doing
4081 // USE_REL is true for REL relocs rather than RELA relocs.
4083 // If PLT_GOT is not NULL, then DT_PLTGOT points to it.
4085 // If PLT_REL is not NULL, it is used for DT_PLTRELSZ, and DT_JMPREL,
4086 // and we also set DT_PLTREL. We use PLT_REL's output section, since
4087 // some targets have multiple reloc sections in PLT_REL.
4089 // If DYN_REL is not NULL, it is used for DT_REL/DT_RELA,
4090 // DT_RELSZ/DT_RELASZ, DT_RELENT/DT_RELAENT. Again we use the output
4093 // If ADD_DEBUG is true, we add a DT_DEBUG entry when generating an
4097 Layout::add_target_dynamic_tags(bool use_rel
, const Output_data
* plt_got
,
4098 const Output_data
* plt_rel
,
4099 const Output_data_reloc_generic
* dyn_rel
,
4100 bool add_debug
, bool dynrel_includes_plt
)
4102 Output_data_dynamic
* odyn
= this->dynamic_data_
;
4106 if (plt_got
!= NULL
&& plt_got
->output_section() != NULL
)
4107 odyn
->add_section_address(elfcpp::DT_PLTGOT
, plt_got
);
4109 if (plt_rel
!= NULL
&& plt_rel
->output_section() != NULL
)
4111 odyn
->add_section_size(elfcpp::DT_PLTRELSZ
, plt_rel
->output_section());
4112 odyn
->add_section_address(elfcpp::DT_JMPREL
, plt_rel
->output_section());
4113 odyn
->add_constant(elfcpp::DT_PLTREL
,
4114 use_rel
? elfcpp::DT_REL
: elfcpp::DT_RELA
);
4117 if (dyn_rel
!= NULL
&& dyn_rel
->output_section() != NULL
)
4119 odyn
->add_section_address(use_rel
? elfcpp::DT_REL
: elfcpp::DT_RELA
,
4120 dyn_rel
->output_section());
4122 && plt_rel
->output_section() != NULL
4123 && dynrel_includes_plt
)
4124 odyn
->add_section_size(use_rel
? elfcpp::DT_RELSZ
: elfcpp::DT_RELASZ
,
4125 dyn_rel
->output_section(),
4126 plt_rel
->output_section());
4128 odyn
->add_section_size(use_rel
? elfcpp::DT_RELSZ
: elfcpp::DT_RELASZ
,
4129 dyn_rel
->output_section());
4130 const int size
= parameters
->target().get_size();
4135 rel_tag
= elfcpp::DT_RELENT
;
4137 rel_size
= Reloc_types
<elfcpp::SHT_REL
, 32, false>::reloc_size
;
4138 else if (size
== 64)
4139 rel_size
= Reloc_types
<elfcpp::SHT_REL
, 64, false>::reloc_size
;
4145 rel_tag
= elfcpp::DT_RELAENT
;
4147 rel_size
= Reloc_types
<elfcpp::SHT_RELA
, 32, false>::reloc_size
;
4148 else if (size
== 64)
4149 rel_size
= Reloc_types
<elfcpp::SHT_RELA
, 64, false>::reloc_size
;
4153 odyn
->add_constant(rel_tag
, rel_size
);
4155 if (parameters
->options().combreloc())
4157 size_t c
= dyn_rel
->relative_reloc_count();
4159 odyn
->add_constant((use_rel
4160 ? elfcpp::DT_RELCOUNT
4161 : elfcpp::DT_RELACOUNT
),
4166 if (add_debug
&& !parameters
->options().shared())
4168 // The value of the DT_DEBUG tag is filled in by the dynamic
4169 // linker at run time, and used by the debugger.
4170 odyn
->add_constant(elfcpp::DT_DEBUG
, 0);
4174 // Finish the .dynamic section and PT_DYNAMIC segment.
4177 Layout::finish_dynamic_section(const Input_objects
* input_objects
,
4178 const Symbol_table
* symtab
)
4180 if (!this->script_options_
->saw_phdrs_clause()
4181 && this->dynamic_section_
!= NULL
)
4183 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_DYNAMIC
,
4186 oseg
->add_output_section_to_nonload(this->dynamic_section_
,
4187 elfcpp::PF_R
| elfcpp::PF_W
);
4190 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
4194 for (Input_objects::Dynobj_iterator p
= input_objects
->dynobj_begin();
4195 p
!= input_objects
->dynobj_end();
4198 if (!(*p
)->is_needed() && (*p
)->as_needed())
4200 // This dynamic object was linked with --as-needed, but it
4205 odyn
->add_string(elfcpp::DT_NEEDED
, (*p
)->soname());
4208 if (parameters
->options().shared())
4210 const char* soname
= parameters
->options().soname();
4212 odyn
->add_string(elfcpp::DT_SONAME
, soname
);
4215 Symbol
* sym
= symtab
->lookup(parameters
->options().init());
4216 if (sym
!= NULL
&& sym
->is_defined() && !sym
->is_from_dynobj())
4217 odyn
->add_symbol(elfcpp::DT_INIT
, sym
);
4219 sym
= symtab
->lookup(parameters
->options().fini());
4220 if (sym
!= NULL
&& sym
->is_defined() && !sym
->is_from_dynobj())
4221 odyn
->add_symbol(elfcpp::DT_FINI
, sym
);
4223 // Look for .init_array, .preinit_array and .fini_array by checking
4225 for(Layout::Section_list::const_iterator p
= this->section_list_
.begin();
4226 p
!= this->section_list_
.end();
4228 switch((*p
)->type())
4230 case elfcpp::SHT_FINI_ARRAY
:
4231 odyn
->add_section_address(elfcpp::DT_FINI_ARRAY
, *p
);
4232 odyn
->add_section_size(elfcpp::DT_FINI_ARRAYSZ
, *p
);
4234 case elfcpp::SHT_INIT_ARRAY
:
4235 odyn
->add_section_address(elfcpp::DT_INIT_ARRAY
, *p
);
4236 odyn
->add_section_size(elfcpp::DT_INIT_ARRAYSZ
, *p
);
4238 case elfcpp::SHT_PREINIT_ARRAY
:
4239 odyn
->add_section_address(elfcpp::DT_PREINIT_ARRAY
, *p
);
4240 odyn
->add_section_size(elfcpp::DT_PREINIT_ARRAYSZ
, *p
);
4246 // Add a DT_RPATH entry if needed.
4247 const General_options::Dir_list
& rpath(parameters
->options().rpath());
4250 std::string rpath_val
;
4251 for (General_options::Dir_list::const_iterator p
= rpath
.begin();
4255 if (rpath_val
.empty())
4256 rpath_val
= p
->name();
4259 // Eliminate duplicates.
4260 General_options::Dir_list::const_iterator q
;
4261 for (q
= rpath
.begin(); q
!= p
; ++q
)
4262 if (q
->name() == p
->name())
4267 rpath_val
+= p
->name();
4272 odyn
->add_string(elfcpp::DT_RPATH
, rpath_val
);
4273 if (parameters
->options().enable_new_dtags())
4274 odyn
->add_string(elfcpp::DT_RUNPATH
, rpath_val
);
4277 // Look for text segments that have dynamic relocations.
4278 bool have_textrel
= false;
4279 if (!this->script_options_
->saw_sections_clause())
4281 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
4282 p
!= this->segment_list_
.end();
4285 if ((*p
)->type() == elfcpp::PT_LOAD
4286 && ((*p
)->flags() & elfcpp::PF_W
) == 0
4287 && (*p
)->has_dynamic_reloc())
4289 have_textrel
= true;
4296 // We don't know the section -> segment mapping, so we are
4297 // conservative and just look for readonly sections with
4298 // relocations. If those sections wind up in writable segments,
4299 // then we have created an unnecessary DT_TEXTREL entry.
4300 for (Section_list::const_iterator p
= this->section_list_
.begin();
4301 p
!= this->section_list_
.end();
4304 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) != 0
4305 && ((*p
)->flags() & elfcpp::SHF_WRITE
) == 0
4306 && (*p
)->has_dynamic_reloc())
4308 have_textrel
= true;
4314 if (parameters
->options().filter() != NULL
)
4315 odyn
->add_string(elfcpp::DT_FILTER
, parameters
->options().filter());
4316 if (parameters
->options().any_auxiliary())
4318 for (options::String_set::const_iterator p
=
4319 parameters
->options().auxiliary_begin();
4320 p
!= parameters
->options().auxiliary_end();
4322 odyn
->add_string(elfcpp::DT_AUXILIARY
, *p
);
4325 // Add a DT_FLAGS entry if necessary.
4326 unsigned int flags
= 0;
4329 // Add a DT_TEXTREL for compatibility with older loaders.
4330 odyn
->add_constant(elfcpp::DT_TEXTREL
, 0);
4331 flags
|= elfcpp::DF_TEXTREL
;
4333 if (parameters
->options().text())
4334 gold_error(_("read-only segment has dynamic relocations"));
4335 else if (parameters
->options().warn_shared_textrel()
4336 && parameters
->options().shared())
4337 gold_warning(_("shared library text segment is not shareable"));
4339 if (parameters
->options().shared() && this->has_static_tls())
4340 flags
|= elfcpp::DF_STATIC_TLS
;
4341 if (parameters
->options().origin())
4342 flags
|= elfcpp::DF_ORIGIN
;
4343 if (parameters
->options().Bsymbolic())
4345 flags
|= elfcpp::DF_SYMBOLIC
;
4346 // Add DT_SYMBOLIC for compatibility with older loaders.
4347 odyn
->add_constant(elfcpp::DT_SYMBOLIC
, 0);
4349 if (parameters
->options().now())
4350 flags
|= elfcpp::DF_BIND_NOW
;
4352 odyn
->add_constant(elfcpp::DT_FLAGS
, flags
);
4355 if (parameters
->options().initfirst())
4356 flags
|= elfcpp::DF_1_INITFIRST
;
4357 if (parameters
->options().interpose())
4358 flags
|= elfcpp::DF_1_INTERPOSE
;
4359 if (parameters
->options().loadfltr())
4360 flags
|= elfcpp::DF_1_LOADFLTR
;
4361 if (parameters
->options().nodefaultlib())
4362 flags
|= elfcpp::DF_1_NODEFLIB
;
4363 if (parameters
->options().nodelete())
4364 flags
|= elfcpp::DF_1_NODELETE
;
4365 if (parameters
->options().nodlopen())
4366 flags
|= elfcpp::DF_1_NOOPEN
;
4367 if (parameters
->options().nodump())
4368 flags
|= elfcpp::DF_1_NODUMP
;
4369 if (!parameters
->options().shared())
4370 flags
&= ~(elfcpp::DF_1_INITFIRST
4371 | elfcpp::DF_1_NODELETE
4372 | elfcpp::DF_1_NOOPEN
);
4373 if (parameters
->options().origin())
4374 flags
|= elfcpp::DF_1_ORIGIN
;
4375 if (parameters
->options().now())
4376 flags
|= elfcpp::DF_1_NOW
;
4377 if (parameters
->options().Bgroup())
4378 flags
|= elfcpp::DF_1_GROUP
;
4380 odyn
->add_constant(elfcpp::DT_FLAGS_1
, flags
);
4383 // Set the size of the _DYNAMIC symbol table to be the size of the
4387 Layout::set_dynamic_symbol_size(const Symbol_table
* symtab
)
4389 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
4392 odyn
->finalize_data_size();
4393 if (this->dynamic_symbol_
== NULL
)
4395 off_t data_size
= odyn
->data_size();
4396 const int size
= parameters
->target().get_size();
4398 symtab
->get_sized_symbol
<32>(this->dynamic_symbol_
)->set_symsize(data_size
);
4399 else if (size
== 64)
4400 symtab
->get_sized_symbol
<64>(this->dynamic_symbol_
)->set_symsize(data_size
);
4405 // The mapping of input section name prefixes to output section names.
4406 // In some cases one prefix is itself a prefix of another prefix; in
4407 // such a case the longer prefix must come first. These prefixes are
4408 // based on the GNU linker default ELF linker script.
4410 #define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 }
4411 const Layout::Section_name_mapping
Layout::section_name_mapping
[] =
4413 MAPPING_INIT(".text.", ".text"),
4414 MAPPING_INIT(".rodata.", ".rodata"),
4415 MAPPING_INIT(".data.rel.ro.local", ".data.rel.ro.local"),
4416 MAPPING_INIT(".data.rel.ro", ".data.rel.ro"),
4417 MAPPING_INIT(".data.", ".data"),
4418 MAPPING_INIT(".bss.", ".bss"),
4419 MAPPING_INIT(".tdata.", ".tdata"),
4420 MAPPING_INIT(".tbss.", ".tbss"),
4421 MAPPING_INIT(".init_array.", ".init_array"),
4422 MAPPING_INIT(".fini_array.", ".fini_array"),
4423 MAPPING_INIT(".sdata.", ".sdata"),
4424 MAPPING_INIT(".sbss.", ".sbss"),
4425 // FIXME: In the GNU linker, .sbss2 and .sdata2 are handled
4426 // differently depending on whether it is creating a shared library.
4427 MAPPING_INIT(".sdata2.", ".sdata"),
4428 MAPPING_INIT(".sbss2.", ".sbss"),
4429 MAPPING_INIT(".lrodata.", ".lrodata"),
4430 MAPPING_INIT(".ldata.", ".ldata"),
4431 MAPPING_INIT(".lbss.", ".lbss"),
4432 MAPPING_INIT(".gcc_except_table.", ".gcc_except_table"),
4433 MAPPING_INIT(".gnu.linkonce.d.rel.ro.local.", ".data.rel.ro.local"),
4434 MAPPING_INIT(".gnu.linkonce.d.rel.ro.", ".data.rel.ro"),
4435 MAPPING_INIT(".gnu.linkonce.t.", ".text"),
4436 MAPPING_INIT(".gnu.linkonce.r.", ".rodata"),
4437 MAPPING_INIT(".gnu.linkonce.d.", ".data"),
4438 MAPPING_INIT(".gnu.linkonce.b.", ".bss"),
4439 MAPPING_INIT(".gnu.linkonce.s.", ".sdata"),
4440 MAPPING_INIT(".gnu.linkonce.sb.", ".sbss"),
4441 MAPPING_INIT(".gnu.linkonce.s2.", ".sdata"),
4442 MAPPING_INIT(".gnu.linkonce.sb2.", ".sbss"),
4443 MAPPING_INIT(".gnu.linkonce.wi.", ".debug_info"),
4444 MAPPING_INIT(".gnu.linkonce.td.", ".tdata"),
4445 MAPPING_INIT(".gnu.linkonce.tb.", ".tbss"),
4446 MAPPING_INIT(".gnu.linkonce.lr.", ".lrodata"),
4447 MAPPING_INIT(".gnu.linkonce.l.", ".ldata"),
4448 MAPPING_INIT(".gnu.linkonce.lb.", ".lbss"),
4449 MAPPING_INIT(".ARM.extab", ".ARM.extab"),
4450 MAPPING_INIT(".gnu.linkonce.armextab.", ".ARM.extab"),
4451 MAPPING_INIT(".ARM.exidx", ".ARM.exidx"),
4452 MAPPING_INIT(".gnu.linkonce.armexidx.", ".ARM.exidx"),
4456 const int Layout::section_name_mapping_count
=
4457 (sizeof(Layout::section_name_mapping
)
4458 / sizeof(Layout::section_name_mapping
[0]));
4460 // Choose the output section name to use given an input section name.
4461 // Set *PLEN to the length of the name. *PLEN is initialized to the
4465 Layout::output_section_name(const Relobj
* relobj
, const char* name
,
4468 // gcc 4.3 generates the following sorts of section names when it
4469 // needs a section name specific to a function:
4475 // .data.rel.local.FN
4477 // .data.rel.ro.local.FN
4484 // The GNU linker maps all of those to the part before the .FN,
4485 // except that .data.rel.local.FN is mapped to .data, and
4486 // .data.rel.ro.local.FN is mapped to .data.rel.ro. The sections
4487 // beginning with .data.rel.ro.local are grouped together.
4489 // For an anonymous namespace, the string FN can contain a '.'.
4491 // Also of interest: .rodata.strN.N, .rodata.cstN, both of which the
4492 // GNU linker maps to .rodata.
4494 // The .data.rel.ro sections are used with -z relro. The sections
4495 // are recognized by name. We use the same names that the GNU
4496 // linker does for these sections.
4498 // It is hard to handle this in a principled way, so we don't even
4499 // try. We use a table of mappings. If the input section name is
4500 // not found in the table, we simply use it as the output section
4503 const Section_name_mapping
* psnm
= section_name_mapping
;
4504 for (int i
= 0; i
< section_name_mapping_count
; ++i
, ++psnm
)
4506 if (strncmp(name
, psnm
->from
, psnm
->fromlen
) == 0)
4508 *plen
= psnm
->tolen
;
4513 // As an additional complication, .ctors sections are output in
4514 // either .ctors or .init_array sections, and .dtors sections are
4515 // output in either .dtors or .fini_array sections.
4516 if (is_prefix_of(".ctors.", name
) || is_prefix_of(".dtors.", name
))
4518 if (parameters
->options().ctors_in_init_array())
4521 return name
[1] == 'c' ? ".init_array" : ".fini_array";
4526 return name
[1] == 'c' ? ".ctors" : ".dtors";
4529 if (parameters
->options().ctors_in_init_array()
4530 && (strcmp(name
, ".ctors") == 0 || strcmp(name
, ".dtors") == 0))
4532 // To make .init_array/.fini_array work with gcc we must exclude
4533 // .ctors and .dtors sections from the crtbegin and crtend
4536 || (!Layout::match_file_name(relobj
, "crtbegin")
4537 && !Layout::match_file_name(relobj
, "crtend")))
4540 return name
[1] == 'c' ? ".init_array" : ".fini_array";
4547 // Return true if RELOBJ is an input file whose base name matches
4548 // FILE_NAME. The base name must have an extension of ".o", and must
4549 // be exactly FILE_NAME.o or FILE_NAME, one character, ".o". This is
4550 // to match crtbegin.o as well as crtbeginS.o without getting confused
4551 // by other possibilities. Overall matching the file name this way is
4552 // a dreadful hack, but the GNU linker does it in order to better
4553 // support gcc, and we need to be compatible.
4556 Layout::match_file_name(const Relobj
* relobj
, const char* match
)
4558 const std::string
& file_name(relobj
->name());
4559 const char* base_name
= lbasename(file_name
.c_str());
4560 size_t match_len
= strlen(match
);
4561 if (strncmp(base_name
, match
, match_len
) != 0)
4563 size_t base_len
= strlen(base_name
);
4564 if (base_len
!= match_len
+ 2 && base_len
!= match_len
+ 3)
4566 return memcmp(base_name
+ base_len
- 2, ".o", 2) == 0;
4569 // Check if a comdat group or .gnu.linkonce section with the given
4570 // NAME is selected for the link. If there is already a section,
4571 // *KEPT_SECTION is set to point to the existing section and the
4572 // function returns false. Otherwise, OBJECT, SHNDX, IS_COMDAT, and
4573 // IS_GROUP_NAME are recorded for this NAME in the layout object,
4574 // *KEPT_SECTION is set to the internal copy and the function returns
4578 Layout::find_or_add_kept_section(const std::string
& name
,
4583 Kept_section
** kept_section
)
4585 // It's normal to see a couple of entries here, for the x86 thunk
4586 // sections. If we see more than a few, we're linking a C++
4587 // program, and we resize to get more space to minimize rehashing.
4588 if (this->signatures_
.size() > 4
4589 && !this->resized_signatures_
)
4591 reserve_unordered_map(&this->signatures_
,
4592 this->number_of_input_files_
* 64);
4593 this->resized_signatures_
= true;
4596 Kept_section candidate
;
4597 std::pair
<Signatures::iterator
, bool> ins
=
4598 this->signatures_
.insert(std::make_pair(name
, candidate
));
4600 if (kept_section
!= NULL
)
4601 *kept_section
= &ins
.first
->second
;
4604 // This is the first time we've seen this signature.
4605 ins
.first
->second
.set_object(object
);
4606 ins
.first
->second
.set_shndx(shndx
);
4608 ins
.first
->second
.set_is_comdat();
4610 ins
.first
->second
.set_is_group_name();
4614 // We have already seen this signature.
4616 if (ins
.first
->second
.is_group_name())
4618 // We've already seen a real section group with this signature.
4619 // If the kept group is from a plugin object, and we're in the
4620 // replacement phase, accept the new one as a replacement.
4621 if (ins
.first
->second
.object() == NULL
4622 && parameters
->options().plugins()->in_replacement_phase())
4624 ins
.first
->second
.set_object(object
);
4625 ins
.first
->second
.set_shndx(shndx
);
4630 else if (is_group_name
)
4632 // This is a real section group, and we've already seen a
4633 // linkonce section with this signature. Record that we've seen
4634 // a section group, and don't include this section group.
4635 ins
.first
->second
.set_is_group_name();
4640 // We've already seen a linkonce section and this is a linkonce
4641 // section. These don't block each other--this may be the same
4642 // symbol name with different section types.
4647 // Store the allocated sections into the section list.
4650 Layout::get_allocated_sections(Section_list
* section_list
) const
4652 for (Section_list::const_iterator p
= this->section_list_
.begin();
4653 p
!= this->section_list_
.end();
4655 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) != 0)
4656 section_list
->push_back(*p
);
4659 // Create an output segment.
4662 Layout::make_output_segment(elfcpp::Elf_Word type
, elfcpp::Elf_Word flags
)
4664 gold_assert(!parameters
->options().relocatable());
4665 Output_segment
* oseg
= new Output_segment(type
, flags
);
4666 this->segment_list_
.push_back(oseg
);
4668 if (type
== elfcpp::PT_TLS
)
4669 this->tls_segment_
= oseg
;
4670 else if (type
== elfcpp::PT_GNU_RELRO
)
4671 this->relro_segment_
= oseg
;
4672 else if (type
== elfcpp::PT_INTERP
)
4673 this->interp_segment_
= oseg
;
4678 // Return the file offset of the normal symbol table.
4681 Layout::symtab_section_offset() const
4683 if (this->symtab_section_
!= NULL
)
4684 return this->symtab_section_
->offset();
4688 // Return the section index of the normal symbol table. It may have
4689 // been stripped by the -s/--strip-all option.
4692 Layout::symtab_section_shndx() const
4694 if (this->symtab_section_
!= NULL
)
4695 return this->symtab_section_
->out_shndx();
4699 // Write out the Output_sections. Most won't have anything to write,
4700 // since most of the data will come from input sections which are
4701 // handled elsewhere. But some Output_sections do have Output_data.
4704 Layout::write_output_sections(Output_file
* of
) const
4706 for (Section_list::const_iterator p
= this->section_list_
.begin();
4707 p
!= this->section_list_
.end();
4710 if (!(*p
)->after_input_sections())
4715 // Write out data not associated with a section or the symbol table.
4718 Layout::write_data(const Symbol_table
* symtab
, Output_file
* of
) const
4720 if (!parameters
->options().strip_all())
4722 const Output_section
* symtab_section
= this->symtab_section_
;
4723 for (Section_list::const_iterator p
= this->section_list_
.begin();
4724 p
!= this->section_list_
.end();
4727 if ((*p
)->needs_symtab_index())
4729 gold_assert(symtab_section
!= NULL
);
4730 unsigned int index
= (*p
)->symtab_index();
4731 gold_assert(index
> 0 && index
!= -1U);
4732 off_t off
= (symtab_section
->offset()
4733 + index
* symtab_section
->entsize());
4734 symtab
->write_section_symbol(*p
, this->symtab_xindex_
, of
, off
);
4739 const Output_section
* dynsym_section
= this->dynsym_section_
;
4740 for (Section_list::const_iterator p
= this->section_list_
.begin();
4741 p
!= this->section_list_
.end();
4744 if ((*p
)->needs_dynsym_index())
4746 gold_assert(dynsym_section
!= NULL
);
4747 unsigned int index
= (*p
)->dynsym_index();
4748 gold_assert(index
> 0 && index
!= -1U);
4749 off_t off
= (dynsym_section
->offset()
4750 + index
* dynsym_section
->entsize());
4751 symtab
->write_section_symbol(*p
, this->dynsym_xindex_
, of
, off
);
4755 // Write out the Output_data which are not in an Output_section.
4756 for (Data_list::const_iterator p
= this->special_output_list_
.begin();
4757 p
!= this->special_output_list_
.end();
4762 // Write out the Output_sections which can only be written after the
4763 // input sections are complete.
4766 Layout::write_sections_after_input_sections(Output_file
* of
)
4768 // Determine the final section offsets, and thus the final output
4769 // file size. Note we finalize the .shstrab last, to allow the
4770 // after_input_section sections to modify their section-names before
4772 if (this->any_postprocessing_sections_
)
4774 off_t off
= this->output_file_size_
;
4775 off
= this->set_section_offsets(off
, POSTPROCESSING_SECTIONS_PASS
);
4777 // Now that we've finalized the names, we can finalize the shstrab.
4779 this->set_section_offsets(off
,
4780 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
);
4782 if (off
> this->output_file_size_
)
4785 this->output_file_size_
= off
;
4789 for (Section_list::const_iterator p
= this->section_list_
.begin();
4790 p
!= this->section_list_
.end();
4793 if ((*p
)->after_input_sections())
4797 this->section_headers_
->write(of
);
4800 // If the build ID requires computing a checksum, do so here, and
4801 // write it out. We compute a checksum over the entire file because
4802 // that is simplest.
4805 Layout::write_build_id(Output_file
* of
) const
4807 if (this->build_id_note_
== NULL
)
4810 const unsigned char* iv
= of
->get_input_view(0, this->output_file_size_
);
4812 unsigned char* ov
= of
->get_output_view(this->build_id_note_
->offset(),
4813 this->build_id_note_
->data_size());
4815 const char* style
= parameters
->options().build_id();
4816 if (strcmp(style
, "sha1") == 0)
4819 sha1_init_ctx(&ctx
);
4820 sha1_process_bytes(iv
, this->output_file_size_
, &ctx
);
4821 sha1_finish_ctx(&ctx
, ov
);
4823 else if (strcmp(style
, "md5") == 0)
4827 md5_process_bytes(iv
, this->output_file_size_
, &ctx
);
4828 md5_finish_ctx(&ctx
, ov
);
4833 of
->write_output_view(this->build_id_note_
->offset(),
4834 this->build_id_note_
->data_size(),
4837 of
->free_input_view(0, this->output_file_size_
, iv
);
4840 // Write out a binary file. This is called after the link is
4841 // complete. IN is the temporary output file we used to generate the
4842 // ELF code. We simply walk through the segments, read them from
4843 // their file offset in IN, and write them to their load address in
4844 // the output file. FIXME: with a bit more work, we could support
4845 // S-records and/or Intel hex format here.
4848 Layout::write_binary(Output_file
* in
) const
4850 gold_assert(parameters
->options().oformat_enum()
4851 == General_options::OBJECT_FORMAT_BINARY
);
4853 // Get the size of the binary file.
4854 uint64_t max_load_address
= 0;
4855 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
4856 p
!= this->segment_list_
.end();
4859 if ((*p
)->type() == elfcpp::PT_LOAD
&& (*p
)->filesz() > 0)
4861 uint64_t max_paddr
= (*p
)->paddr() + (*p
)->filesz();
4862 if (max_paddr
> max_load_address
)
4863 max_load_address
= max_paddr
;
4867 Output_file
out(parameters
->options().output_file_name());
4868 out
.open(max_load_address
);
4870 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
4871 p
!= this->segment_list_
.end();
4874 if ((*p
)->type() == elfcpp::PT_LOAD
&& (*p
)->filesz() > 0)
4876 const unsigned char* vin
= in
->get_input_view((*p
)->offset(),
4878 unsigned char* vout
= out
.get_output_view((*p
)->paddr(),
4880 memcpy(vout
, vin
, (*p
)->filesz());
4881 out
.write_output_view((*p
)->paddr(), (*p
)->filesz(), vout
);
4882 in
->free_input_view((*p
)->offset(), (*p
)->filesz(), vin
);
4889 // Print the output sections to the map file.
4892 Layout::print_to_mapfile(Mapfile
* mapfile
) const
4894 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
4895 p
!= this->segment_list_
.end();
4897 (*p
)->print_sections_to_mapfile(mapfile
);
4900 // Print statistical information to stderr. This is used for --stats.
4903 Layout::print_stats() const
4905 this->namepool_
.print_stats("section name pool");
4906 this->sympool_
.print_stats("output symbol name pool");
4907 this->dynpool_
.print_stats("dynamic name pool");
4909 for (Section_list::const_iterator p
= this->section_list_
.begin();
4910 p
!= this->section_list_
.end();
4912 (*p
)->print_merge_stats();
4915 // Write_sections_task methods.
4917 // We can always run this task.
4920 Write_sections_task::is_runnable()
4925 // We need to unlock both OUTPUT_SECTIONS_BLOCKER and FINAL_BLOCKER
4929 Write_sections_task::locks(Task_locker
* tl
)
4931 tl
->add(this, this->output_sections_blocker_
);
4932 tl
->add(this, this->final_blocker_
);
4935 // Run the task--write out the data.
4938 Write_sections_task::run(Workqueue
*)
4940 this->layout_
->write_output_sections(this->of_
);
4943 // Write_data_task methods.
4945 // We can always run this task.
4948 Write_data_task::is_runnable()
4953 // We need to unlock FINAL_BLOCKER when finished.
4956 Write_data_task::locks(Task_locker
* tl
)
4958 tl
->add(this, this->final_blocker_
);
4961 // Run the task--write out the data.
4964 Write_data_task::run(Workqueue
*)
4966 this->layout_
->write_data(this->symtab_
, this->of_
);
4969 // Write_symbols_task methods.
4971 // We can always run this task.
4974 Write_symbols_task::is_runnable()
4979 // We need to unlock FINAL_BLOCKER when finished.
4982 Write_symbols_task::locks(Task_locker
* tl
)
4984 tl
->add(this, this->final_blocker_
);
4987 // Run the task--write out the symbols.
4990 Write_symbols_task::run(Workqueue
*)
4992 this->symtab_
->write_globals(this->sympool_
, this->dynpool_
,
4993 this->layout_
->symtab_xindex(),
4994 this->layout_
->dynsym_xindex(), this->of_
);
4997 // Write_after_input_sections_task methods.
4999 // We can only run this task after the input sections have completed.
5002 Write_after_input_sections_task::is_runnable()
5004 if (this->input_sections_blocker_
->is_blocked())
5005 return this->input_sections_blocker_
;
5009 // We need to unlock FINAL_BLOCKER when finished.
5012 Write_after_input_sections_task::locks(Task_locker
* tl
)
5014 tl
->add(this, this->final_blocker_
);
5020 Write_after_input_sections_task::run(Workqueue
*)
5022 this->layout_
->write_sections_after_input_sections(this->of_
);
5025 // Close_task_runner methods.
5027 // Run the task--close the file.
5030 Close_task_runner::run(Workqueue
*, const Task
*)
5032 // If we need to compute a checksum for the BUILD if, we do so here.
5033 this->layout_
->write_build_id(this->of_
);
5035 // If we've been asked to create a binary file, we do so here.
5036 if (this->options_
->oformat_enum() != General_options::OBJECT_FORMAT_ELF
)
5037 this->layout_
->write_binary(this->of_
);
5042 // Instantiate the templates we need. We could use the configure
5043 // script to restrict this to only the ones for implemented targets.
5045 #ifdef HAVE_TARGET_32_LITTLE
5048 Layout::init_fixed_output_section
<32, false>(
5050 elfcpp::Shdr
<32, false>& shdr
);
5053 #ifdef HAVE_TARGET_32_BIG
5056 Layout::init_fixed_output_section
<32, true>(
5058 elfcpp::Shdr
<32, true>& shdr
);
5061 #ifdef HAVE_TARGET_64_LITTLE
5064 Layout::init_fixed_output_section
<64, false>(
5066 elfcpp::Shdr
<64, false>& shdr
);
5069 #ifdef HAVE_TARGET_64_BIG
5072 Layout::init_fixed_output_section
<64, true>(
5074 elfcpp::Shdr
<64, true>& shdr
);
5077 #ifdef HAVE_TARGET_32_LITTLE
5080 Layout::layout
<32, false>(Sized_relobj_file
<32, false>* object
,
5083 const elfcpp::Shdr
<32, false>& shdr
,
5084 unsigned int, unsigned int, off_t
*);
5087 #ifdef HAVE_TARGET_32_BIG
5090 Layout::layout
<32, true>(Sized_relobj_file
<32, true>* object
,
5093 const elfcpp::Shdr
<32, true>& shdr
,
5094 unsigned int, unsigned int, off_t
*);
5097 #ifdef HAVE_TARGET_64_LITTLE
5100 Layout::layout
<64, false>(Sized_relobj_file
<64, false>* object
,
5103 const elfcpp::Shdr
<64, false>& shdr
,
5104 unsigned int, unsigned int, off_t
*);
5107 #ifdef HAVE_TARGET_64_BIG
5110 Layout::layout
<64, true>(Sized_relobj_file
<64, true>* object
,
5113 const elfcpp::Shdr
<64, true>& shdr
,
5114 unsigned int, unsigned int, off_t
*);
5117 #ifdef HAVE_TARGET_32_LITTLE
5120 Layout::layout_reloc
<32, false>(Sized_relobj_file
<32, false>* object
,
5121 unsigned int reloc_shndx
,
5122 const elfcpp::Shdr
<32, false>& shdr
,
5123 Output_section
* data_section
,
5124 Relocatable_relocs
* rr
);
5127 #ifdef HAVE_TARGET_32_BIG
5130 Layout::layout_reloc
<32, true>(Sized_relobj_file
<32, true>* object
,
5131 unsigned int reloc_shndx
,
5132 const elfcpp::Shdr
<32, true>& shdr
,
5133 Output_section
* data_section
,
5134 Relocatable_relocs
* rr
);
5137 #ifdef HAVE_TARGET_64_LITTLE
5140 Layout::layout_reloc
<64, false>(Sized_relobj_file
<64, false>* object
,
5141 unsigned int reloc_shndx
,
5142 const elfcpp::Shdr
<64, false>& shdr
,
5143 Output_section
* data_section
,
5144 Relocatable_relocs
* rr
);
5147 #ifdef HAVE_TARGET_64_BIG
5150 Layout::layout_reloc
<64, true>(Sized_relobj_file
<64, true>* object
,
5151 unsigned int reloc_shndx
,
5152 const elfcpp::Shdr
<64, true>& shdr
,
5153 Output_section
* data_section
,
5154 Relocatable_relocs
* rr
);
5157 #ifdef HAVE_TARGET_32_LITTLE
5160 Layout::layout_group
<32, false>(Symbol_table
* symtab
,
5161 Sized_relobj_file
<32, false>* object
,
5163 const char* group_section_name
,
5164 const char* signature
,
5165 const elfcpp::Shdr
<32, false>& shdr
,
5166 elfcpp::Elf_Word flags
,
5167 std::vector
<unsigned int>* shndxes
);
5170 #ifdef HAVE_TARGET_32_BIG
5173 Layout::layout_group
<32, true>(Symbol_table
* symtab
,
5174 Sized_relobj_file
<32, true>* object
,
5176 const char* group_section_name
,
5177 const char* signature
,
5178 const elfcpp::Shdr
<32, true>& shdr
,
5179 elfcpp::Elf_Word flags
,
5180 std::vector
<unsigned int>* shndxes
);
5183 #ifdef HAVE_TARGET_64_LITTLE
5186 Layout::layout_group
<64, false>(Symbol_table
* symtab
,
5187 Sized_relobj_file
<64, false>* object
,
5189 const char* group_section_name
,
5190 const char* signature
,
5191 const elfcpp::Shdr
<64, false>& shdr
,
5192 elfcpp::Elf_Word flags
,
5193 std::vector
<unsigned int>* shndxes
);
5196 #ifdef HAVE_TARGET_64_BIG
5199 Layout::layout_group
<64, true>(Symbol_table
* symtab
,
5200 Sized_relobj_file
<64, true>* object
,
5202 const char* group_section_name
,
5203 const char* signature
,
5204 const elfcpp::Shdr
<64, true>& shdr
,
5205 elfcpp::Elf_Word flags
,
5206 std::vector
<unsigned int>* shndxes
);
5209 #ifdef HAVE_TARGET_32_LITTLE
5212 Layout::layout_eh_frame
<32, false>(Sized_relobj_file
<32, false>* object
,
5213 const unsigned char* symbols
,
5215 const unsigned char* symbol_names
,
5216 off_t symbol_names_size
,
5218 const elfcpp::Shdr
<32, false>& shdr
,
5219 unsigned int reloc_shndx
,
5220 unsigned int reloc_type
,
5224 #ifdef HAVE_TARGET_32_BIG
5227 Layout::layout_eh_frame
<32, true>(Sized_relobj_file
<32, true>* object
,
5228 const unsigned char* symbols
,
5230 const unsigned char* symbol_names
,
5231 off_t symbol_names_size
,
5233 const elfcpp::Shdr
<32, true>& shdr
,
5234 unsigned int reloc_shndx
,
5235 unsigned int reloc_type
,
5239 #ifdef HAVE_TARGET_64_LITTLE
5242 Layout::layout_eh_frame
<64, false>(Sized_relobj_file
<64, false>* object
,
5243 const unsigned char* symbols
,
5245 const unsigned char* symbol_names
,
5246 off_t symbol_names_size
,
5248 const elfcpp::Shdr
<64, false>& shdr
,
5249 unsigned int reloc_shndx
,
5250 unsigned int reloc_type
,
5254 #ifdef HAVE_TARGET_64_BIG
5257 Layout::layout_eh_frame
<64, true>(Sized_relobj_file
<64, true>* object
,
5258 const unsigned char* symbols
,
5260 const unsigned char* symbol_names
,
5261 off_t symbol_names_size
,
5263 const elfcpp::Shdr
<64, true>& shdr
,
5264 unsigned int reloc_shndx
,
5265 unsigned int reloc_type
,
5269 } // End namespace gold.