1 // layout.cc -- lay out output file sections for gold
3 // Copyright (C) 2006-2014 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 "gdb-index.h"
48 #include "compressed_output.h"
49 #include "reduced_debug_output.h"
52 #include "descriptors.h"
54 #include "incremental.h"
62 // The total number of free lists used.
63 unsigned int Free_list::num_lists
= 0;
64 // The total number of free list nodes used.
65 unsigned int Free_list::num_nodes
= 0;
66 // The total number of calls to Free_list::remove.
67 unsigned int Free_list::num_removes
= 0;
68 // The total number of nodes visited during calls to Free_list::remove.
69 unsigned int Free_list::num_remove_visits
= 0;
70 // The total number of calls to Free_list::allocate.
71 unsigned int Free_list::num_allocates
= 0;
72 // The total number of nodes visited during calls to Free_list::allocate.
73 unsigned int Free_list::num_allocate_visits
= 0;
75 // Initialize the free list. Creates a single free list node that
76 // describes the entire region of length LEN. If EXTEND is true,
77 // allocate() is allowed to extend the region beyond its initial
81 Free_list::init(off_t len
, bool extend
)
83 this->list_
.push_front(Free_list_node(0, len
));
84 this->last_remove_
= this->list_
.begin();
85 this->extend_
= extend
;
87 ++Free_list::num_lists
;
88 ++Free_list::num_nodes
;
91 // Remove a chunk from the free list. Because we start with a single
92 // node that covers the entire section, and remove chunks from it one
93 // at a time, we do not need to coalesce chunks or handle cases that
94 // span more than one free node. We expect to remove chunks from the
95 // free list in order, and we expect to have only a few chunks of free
96 // space left (corresponding to files that have changed since the last
97 // incremental link), so a simple linear list should provide sufficient
101 Free_list::remove(off_t start
, off_t end
)
105 gold_assert(start
< end
);
107 ++Free_list::num_removes
;
109 Iterator p
= this->last_remove_
;
110 if (p
->start_
> start
)
111 p
= this->list_
.begin();
113 for (; p
!= this->list_
.end(); ++p
)
115 ++Free_list::num_remove_visits
;
116 // Find a node that wholly contains the indicated region.
117 if (p
->start_
<= start
&& p
->end_
>= end
)
119 // Case 1: the indicated region spans the whole node.
120 // Add some fuzz to avoid creating tiny free chunks.
121 if (p
->start_
+ 3 >= start
&& p
->end_
<= end
+ 3)
122 p
= this->list_
.erase(p
);
123 // Case 2: remove a chunk from the start of the node.
124 else if (p
->start_
+ 3 >= start
)
126 // Case 3: remove a chunk from the end of the node.
127 else if (p
->end_
<= end
+ 3)
129 // Case 4: remove a chunk from the middle, and split
130 // the node into two.
133 Free_list_node
newnode(p
->start_
, start
);
135 this->list_
.insert(p
, newnode
);
136 ++Free_list::num_nodes
;
138 this->last_remove_
= p
;
143 // Did not find a node containing the given chunk. This could happen
144 // because a small chunk was already removed due to the fuzz.
145 gold_debug(DEBUG_INCREMENTAL
,
146 "Free_list::remove(%d,%d) not found",
147 static_cast<int>(start
), static_cast<int>(end
));
150 // Allocate a chunk of size LEN from the free list. Returns -1ULL
151 // if a sufficiently large chunk of free space is not found.
152 // We use a simple first-fit algorithm.
155 Free_list::allocate(off_t len
, uint64_t align
, off_t minoff
)
157 gold_debug(DEBUG_INCREMENTAL
,
158 "Free_list::allocate(%08lx, %d, %08lx)",
159 static_cast<long>(len
), static_cast<int>(align
),
160 static_cast<long>(minoff
));
162 return align_address(minoff
, align
);
164 ++Free_list::num_allocates
;
166 // We usually want to drop free chunks smaller than 4 bytes.
167 // If we need to guarantee a minimum hole size, though, we need
168 // to keep track of all free chunks.
169 const int fuzz
= this->min_hole_
> 0 ? 0 : 3;
171 for (Iterator p
= this->list_
.begin(); p
!= this->list_
.end(); ++p
)
173 ++Free_list::num_allocate_visits
;
174 off_t start
= p
->start_
> minoff
? p
->start_
: minoff
;
175 start
= align_address(start
, align
);
176 off_t end
= start
+ len
;
177 if (end
> p
->end_
&& p
->end_
== this->length_
&& this->extend_
)
182 if (end
== p
->end_
|| (end
<= p
->end_
- this->min_hole_
))
184 if (p
->start_
+ fuzz
>= start
&& p
->end_
<= end
+ fuzz
)
185 this->list_
.erase(p
);
186 else if (p
->start_
+ fuzz
>= start
)
188 else if (p
->end_
<= end
+ fuzz
)
192 Free_list_node
newnode(p
->start_
, start
);
194 this->list_
.insert(p
, newnode
);
195 ++Free_list::num_nodes
;
202 off_t start
= align_address(this->length_
, align
);
203 this->length_
= start
+ len
;
209 // Dump the free list (for debugging).
213 gold_info("Free list:\n start end length\n");
214 for (Iterator p
= this->list_
.begin(); p
!= this->list_
.end(); ++p
)
215 gold_info(" %08lx %08lx %08lx", static_cast<long>(p
->start_
),
216 static_cast<long>(p
->end_
),
217 static_cast<long>(p
->end_
- p
->start_
));
220 // Print the statistics for the free lists.
222 Free_list::print_stats()
224 fprintf(stderr
, _("%s: total free lists: %u\n"),
225 program_name
, Free_list::num_lists
);
226 fprintf(stderr
, _("%s: total free list nodes: %u\n"),
227 program_name
, Free_list::num_nodes
);
228 fprintf(stderr
, _("%s: calls to Free_list::remove: %u\n"),
229 program_name
, Free_list::num_removes
);
230 fprintf(stderr
, _("%s: nodes visited: %u\n"),
231 program_name
, Free_list::num_remove_visits
);
232 fprintf(stderr
, _("%s: calls to Free_list::allocate: %u\n"),
233 program_name
, Free_list::num_allocates
);
234 fprintf(stderr
, _("%s: nodes visited: %u\n"),
235 program_name
, Free_list::num_allocate_visits
);
238 // A Hash_task computes the MD5 checksum of an array of char.
239 // It has a blocker on either side (i.e., the task cannot run until
240 // the first is unblocked, and it unblocks the second after running).
242 class Hash_task
: public Task
245 Hash_task(const unsigned char* src
,
248 Task_token
* build_id_blocker
,
249 Task_token
* final_blocker
)
250 : src_(src
), size_(size
), dst_(dst
), build_id_blocker_(build_id_blocker
),
251 final_blocker_(final_blocker
)
256 { md5_buffer(reinterpret_cast<const char*>(src_
), size_
, dst_
); }
261 // Unblock FINAL_BLOCKER_ when done.
263 locks(Task_locker
* tl
)
264 { tl
->add(this, this->final_blocker_
); }
268 { return "Hash_task"; }
271 const unsigned char* const src_
;
273 unsigned char* const dst_
;
274 Task_token
* const build_id_blocker_
;
275 Task_token
* const final_blocker_
;
279 Hash_task::is_runnable()
281 if (this->build_id_blocker_
->is_blocked())
282 return this->build_id_blocker_
;
286 // Layout::Relaxation_debug_check methods.
288 // Check that sections and special data are in reset states.
289 // We do not save states for Output_sections and special Output_data.
290 // So we check that they have not assigned any addresses or offsets.
291 // clean_up_after_relaxation simply resets their addresses and offsets.
293 Layout::Relaxation_debug_check::check_output_data_for_reset_values(
294 const Layout::Section_list
& sections
,
295 const Layout::Data_list
& special_outputs
,
296 const Layout::Data_list
& relax_outputs
)
298 for(Layout::Section_list::const_iterator p
= sections
.begin();
301 gold_assert((*p
)->address_and_file_offset_have_reset_values());
303 for(Layout::Data_list::const_iterator p
= special_outputs
.begin();
304 p
!= special_outputs
.end();
306 gold_assert((*p
)->address_and_file_offset_have_reset_values());
308 gold_assert(relax_outputs
.empty());
311 // Save information of SECTIONS for checking later.
314 Layout::Relaxation_debug_check::read_sections(
315 const Layout::Section_list
& sections
)
317 for(Layout::Section_list::const_iterator p
= sections
.begin();
321 Output_section
* os
= *p
;
323 info
.output_section
= os
;
324 info
.address
= os
->is_address_valid() ? os
->address() : 0;
325 info
.data_size
= os
->is_data_size_valid() ? os
->data_size() : -1;
326 info
.offset
= os
->is_offset_valid()? os
->offset() : -1 ;
327 this->section_infos_
.push_back(info
);
331 // Verify SECTIONS using previously recorded information.
334 Layout::Relaxation_debug_check::verify_sections(
335 const Layout::Section_list
& sections
)
338 for(Layout::Section_list::const_iterator p
= sections
.begin();
342 Output_section
* os
= *p
;
343 uint64_t address
= os
->is_address_valid() ? os
->address() : 0;
344 off_t data_size
= os
->is_data_size_valid() ? os
->data_size() : -1;
345 off_t offset
= os
->is_offset_valid()? os
->offset() : -1 ;
347 if (i
>= this->section_infos_
.size())
349 gold_fatal("Section_info of %s missing.\n", os
->name());
351 const Section_info
& info
= this->section_infos_
[i
];
352 if (os
!= info
.output_section
)
353 gold_fatal("Section order changed. Expecting %s but see %s\n",
354 info
.output_section
->name(), os
->name());
355 if (address
!= info
.address
356 || data_size
!= info
.data_size
357 || offset
!= info
.offset
)
358 gold_fatal("Section %s changed.\n", os
->name());
362 // Layout_task_runner methods.
364 // Lay out the sections. This is called after all the input objects
368 Layout_task_runner::run(Workqueue
* workqueue
, const Task
* task
)
370 // See if any of the input definitions violate the One Definition Rule.
371 // TODO: if this is too slow, do this as a task, rather than inline.
372 this->symtab_
->detect_odr_violations(task
, this->options_
.output_file_name());
374 Layout
* layout
= this->layout_
;
375 off_t file_size
= layout
->finalize(this->input_objects_
,
380 // Now we know the final size of the output file and we know where
381 // each piece of information goes.
383 if (this->mapfile_
!= NULL
)
385 this->mapfile_
->print_discarded_sections(this->input_objects_
);
386 layout
->print_to_mapfile(this->mapfile_
);
390 if (layout
->incremental_base() == NULL
)
392 of
= new Output_file(parameters
->options().output_file_name());
393 if (this->options_
.oformat_enum() != General_options::OBJECT_FORMAT_ELF
)
394 of
->set_is_temporary();
399 of
= layout
->incremental_base()->output_file();
401 // Apply the incremental relocations for symbols whose values
402 // have changed. We do this before we resize the file and start
403 // writing anything else to it, so that we can read the old
404 // incremental information from the file before (possibly)
406 if (parameters
->incremental_update())
407 layout
->incremental_base()->apply_incremental_relocs(this->symtab_
,
411 of
->resize(file_size
);
414 // Queue up the final set of tasks.
415 gold::queue_final_tasks(this->options_
, this->input_objects_
,
416 this->symtab_
, layout
, workqueue
, of
);
421 Layout::Layout(int number_of_input_files
, Script_options
* script_options
)
422 : number_of_input_files_(number_of_input_files
),
423 script_options_(script_options
),
431 unattached_section_list_(),
432 special_output_list_(),
433 relax_output_list_(),
434 section_headers_(NULL
),
436 relro_segment_(NULL
),
437 interp_segment_(NULL
),
439 symtab_section_(NULL
),
440 symtab_xindex_(NULL
),
441 dynsym_section_(NULL
),
442 dynsym_xindex_(NULL
),
443 dynamic_section_(NULL
),
444 dynamic_symbol_(NULL
),
446 eh_frame_section_(NULL
),
447 eh_frame_data_(NULL
),
448 added_eh_frame_data_(false),
449 eh_frame_hdr_section_(NULL
),
450 gdb_index_data_(NULL
),
451 build_id_note_(NULL
),
452 array_of_hashes_(NULL
),
453 size_of_array_of_hashes_(0),
458 output_file_size_(-1),
459 have_added_input_section_(false),
460 sections_are_attached_(false),
461 input_requires_executable_stack_(false),
462 input_with_gnu_stack_note_(false),
463 input_without_gnu_stack_note_(false),
464 has_static_tls_(false),
465 any_postprocessing_sections_(false),
466 resized_signatures_(false),
467 have_stabstr_section_(false),
468 section_ordering_specified_(false),
469 unique_segment_for_sections_specified_(false),
470 incremental_inputs_(NULL
),
471 record_output_section_data_from_script_(false),
472 script_output_section_data_list_(),
473 segment_states_(NULL
),
474 relaxation_debug_check_(NULL
),
475 section_order_map_(),
476 section_segment_map_(),
477 input_section_position_(),
478 input_section_glob_(),
479 incremental_base_(NULL
),
482 // Make space for more than enough segments for a typical file.
483 // This is just for efficiency--it's OK if we wind up needing more.
484 this->segment_list_
.reserve(12);
486 // We expect two unattached Output_data objects: the file header and
487 // the segment headers.
488 this->special_output_list_
.reserve(2);
490 // Initialize structure needed for an incremental build.
491 if (parameters
->incremental())
492 this->incremental_inputs_
= new Incremental_inputs
;
494 // The section name pool is worth optimizing in all cases, because
495 // it is small, but there are often overlaps due to .rel sections.
496 this->namepool_
.set_optimize();
499 // For incremental links, record the base file to be modified.
502 Layout::set_incremental_base(Incremental_binary
* base
)
504 this->incremental_base_
= base
;
505 this->free_list_
.init(base
->output_file()->filesize(), true);
508 // Hash a key we use to look up an output section mapping.
511 Layout::Hash_key::operator()(const Layout::Key
& k
) const
513 return k
.first
+ k
.second
.first
+ k
.second
.second
;
516 // These are the debug sections that are actually used by gdb.
517 // Currently, we've checked versions of gdb up to and including 7.4.
518 // We only check the part of the name that follows ".debug_" or
521 static const char* gdb_sections
[] =
524 "addr", // Fission extension
525 // "aranges", // not used by gdb as of 7.4
534 // "pubnames", // not used by gdb as of 7.4
535 // "pubtypes", // not used by gdb as of 7.4
536 // "gnu_pubnames", // Fission extension
537 // "gnu_pubtypes", // Fission extension
543 // This is the minimum set of sections needed for line numbers.
545 static const char* lines_only_debug_sections
[] =
548 // "addr", // Fission extension
549 // "aranges", // not used by gdb as of 7.4
558 // "pubnames", // not used by gdb as of 7.4
559 // "pubtypes", // not used by gdb as of 7.4
560 // "gnu_pubnames", // Fission extension
561 // "gnu_pubtypes", // Fission extension
564 "str_offsets", // Fission extension
567 // These sections are the DWARF fast-lookup tables, and are not needed
568 // when building a .gdb_index section.
570 static const char* gdb_fast_lookup_sections
[] =
579 // Returns whether the given debug section is in the list of
580 // debug-sections-used-by-some-version-of-gdb. SUFFIX is the
581 // portion of the name following ".debug_" or ".zdebug_".
584 is_gdb_debug_section(const char* suffix
)
586 // We can do this faster: binary search or a hashtable. But why bother?
587 for (size_t i
= 0; i
< sizeof(gdb_sections
)/sizeof(*gdb_sections
); ++i
)
588 if (strcmp(suffix
, gdb_sections
[i
]) == 0)
593 // Returns whether the given section is needed for lines-only debugging.
596 is_lines_only_debug_section(const char* suffix
)
598 // We can do this faster: binary search or a hashtable. But why bother?
600 i
< sizeof(lines_only_debug_sections
)/sizeof(*lines_only_debug_sections
);
602 if (strcmp(suffix
, lines_only_debug_sections
[i
]) == 0)
607 // Returns whether the given section is a fast-lookup section that
608 // will not be needed when building a .gdb_index section.
611 is_gdb_fast_lookup_section(const char* suffix
)
613 // We can do this faster: binary search or a hashtable. But why bother?
615 i
< sizeof(gdb_fast_lookup_sections
)/sizeof(*gdb_fast_lookup_sections
);
617 if (strcmp(suffix
, gdb_fast_lookup_sections
[i
]) == 0)
622 // Sometimes we compress sections. This is typically done for
623 // sections that are not part of normal program execution (such as
624 // .debug_* sections), and where the readers of these sections know
625 // how to deal with compressed sections. This routine doesn't say for
626 // certain whether we'll compress -- it depends on commandline options
627 // as well -- just whether this section is a candidate for compression.
628 // (The Output_compressed_section class decides whether to compress
629 // a given section, and picks the name of the compressed section.)
632 is_compressible_debug_section(const char* secname
)
634 return (is_prefix_of(".debug", secname
));
637 // We may see compressed debug sections in input files. Return TRUE
638 // if this is the name of a compressed debug section.
641 is_compressed_debug_section(const char* secname
)
643 return (is_prefix_of(".zdebug", secname
));
646 // Whether to include this section in the link.
648 template<int size
, bool big_endian
>
650 Layout::include_section(Sized_relobj_file
<size
, big_endian
>*, const char* name
,
651 const elfcpp::Shdr
<size
, big_endian
>& shdr
)
653 if (!parameters
->options().relocatable()
654 && (shdr
.get_sh_flags() & elfcpp::SHF_EXCLUDE
))
657 elfcpp::Elf_Word sh_type
= shdr
.get_sh_type();
659 if ((sh_type
>= elfcpp::SHT_LOOS
&& sh_type
<= elfcpp::SHT_HIOS
)
660 || (sh_type
>= elfcpp::SHT_LOPROC
&& sh_type
<= elfcpp::SHT_HIPROC
))
661 return parameters
->target().should_include_section(sh_type
);
665 case elfcpp::SHT_NULL
:
666 case elfcpp::SHT_SYMTAB
:
667 case elfcpp::SHT_DYNSYM
:
668 case elfcpp::SHT_HASH
:
669 case elfcpp::SHT_DYNAMIC
:
670 case elfcpp::SHT_SYMTAB_SHNDX
:
673 case elfcpp::SHT_STRTAB
:
674 // Discard the sections which have special meanings in the ELF
675 // ABI. Keep others (e.g., .stabstr). We could also do this by
676 // checking the sh_link fields of the appropriate sections.
677 return (strcmp(name
, ".dynstr") != 0
678 && strcmp(name
, ".strtab") != 0
679 && strcmp(name
, ".shstrtab") != 0);
681 case elfcpp::SHT_RELA
:
682 case elfcpp::SHT_REL
:
683 case elfcpp::SHT_GROUP
:
684 // If we are emitting relocations these should be handled
686 gold_assert(!parameters
->options().relocatable());
689 case elfcpp::SHT_PROGBITS
:
690 if (parameters
->options().strip_debug()
691 && (shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) == 0)
693 if (is_debug_info_section(name
))
696 if (parameters
->options().strip_debug_non_line()
697 && (shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) == 0)
699 // Debugging sections can only be recognized by name.
700 if (is_prefix_of(".debug_", name
)
701 && !is_lines_only_debug_section(name
+ 7))
703 if (is_prefix_of(".zdebug_", name
)
704 && !is_lines_only_debug_section(name
+ 8))
707 if (parameters
->options().strip_debug_gdb()
708 && (shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) == 0)
710 // Debugging sections can only be recognized by name.
711 if (is_prefix_of(".debug_", name
)
712 && !is_gdb_debug_section(name
+ 7))
714 if (is_prefix_of(".zdebug_", name
)
715 && !is_gdb_debug_section(name
+ 8))
718 if (parameters
->options().gdb_index()
719 && (shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) == 0)
721 // When building .gdb_index, we can strip .debug_pubnames,
722 // .debug_pubtypes, and .debug_aranges sections.
723 if (is_prefix_of(".debug_", name
)
724 && is_gdb_fast_lookup_section(name
+ 7))
726 if (is_prefix_of(".zdebug_", name
)
727 && is_gdb_fast_lookup_section(name
+ 8))
730 if (parameters
->options().strip_lto_sections()
731 && !parameters
->options().relocatable()
732 && (shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) == 0)
734 // Ignore LTO sections containing intermediate code.
735 if (is_prefix_of(".gnu.lto_", name
))
738 // The GNU linker strips .gnu_debuglink sections, so we do too.
739 // This is a feature used to keep debugging information in
741 if (strcmp(name
, ".gnu_debuglink") == 0)
750 // Return an output section named NAME, or NULL if there is none.
753 Layout::find_output_section(const char* name
) const
755 for (Section_list::const_iterator p
= this->section_list_
.begin();
756 p
!= this->section_list_
.end();
758 if (strcmp((*p
)->name(), name
) == 0)
763 // Return an output segment of type TYPE, with segment flags SET set
764 // and segment flags CLEAR clear. Return NULL if there is none.
767 Layout::find_output_segment(elfcpp::PT type
, elfcpp::Elf_Word set
,
768 elfcpp::Elf_Word clear
) const
770 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
771 p
!= this->segment_list_
.end();
773 if (static_cast<elfcpp::PT
>((*p
)->type()) == type
774 && ((*p
)->flags() & set
) == set
775 && ((*p
)->flags() & clear
) == 0)
780 // When we put a .ctors or .dtors section with more than one word into
781 // a .init_array or .fini_array section, we need to reverse the words
782 // in the .ctors/.dtors section. This is because .init_array executes
783 // constructors front to back, where .ctors executes them back to
784 // front, and vice-versa for .fini_array/.dtors. Although we do want
785 // to remap .ctors/.dtors into .init_array/.fini_array because it can
786 // be more efficient, we don't want to change the order in which
787 // constructors/destructors are run. This set just keeps track of
788 // these sections which need to be reversed. It is only changed by
789 // Layout::layout. It should be a private member of Layout, but that
790 // would require layout.h to #include object.h to get the definition
792 static Unordered_set
<Section_id
, Section_id_hash
> ctors_sections_in_init_array
;
794 // Return whether OBJECT/SHNDX is a .ctors/.dtors section mapped to a
795 // .init_array/.fini_array section.
798 Layout::is_ctors_in_init_array(Relobj
* relobj
, unsigned int shndx
) const
800 return (ctors_sections_in_init_array
.find(Section_id(relobj
, shndx
))
801 != ctors_sections_in_init_array
.end());
804 // Return the output section to use for section NAME with type TYPE
805 // and section flags FLAGS. NAME must be canonicalized in the string
806 // pool, and NAME_KEY is the key. ORDER is where this should appear
807 // in the output sections. IS_RELRO is true for a relro section.
810 Layout::get_output_section(const char* name
, Stringpool::Key name_key
,
811 elfcpp::Elf_Word type
, elfcpp::Elf_Xword flags
,
812 Output_section_order order
, bool is_relro
)
814 elfcpp::Elf_Word lookup_type
= type
;
816 // For lookup purposes, treat INIT_ARRAY, FINI_ARRAY, and
817 // PREINIT_ARRAY like PROGBITS. This ensures that we combine
818 // .init_array, .fini_array, and .preinit_array sections by name
819 // whatever their type in the input file. We do this because the
820 // types are not always right in the input files.
821 if (lookup_type
== elfcpp::SHT_INIT_ARRAY
822 || lookup_type
== elfcpp::SHT_FINI_ARRAY
823 || lookup_type
== elfcpp::SHT_PREINIT_ARRAY
)
824 lookup_type
= elfcpp::SHT_PROGBITS
;
826 elfcpp::Elf_Xword lookup_flags
= flags
;
828 // Ignoring SHF_WRITE and SHF_EXECINSTR here means that we combine
829 // read-write with read-only sections. Some other ELF linkers do
830 // not do this. FIXME: Perhaps there should be an option
832 lookup_flags
&= ~(elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
);
834 const Key
key(name_key
, std::make_pair(lookup_type
, lookup_flags
));
835 const std::pair
<Key
, Output_section
*> v(key
, NULL
);
836 std::pair
<Section_name_map::iterator
, bool> ins(
837 this->section_name_map_
.insert(v
));
840 return ins
.first
->second
;
843 // This is the first time we've seen this name/type/flags
844 // combination. For compatibility with the GNU linker, we
845 // combine sections with contents and zero flags with sections
846 // with non-zero flags. This is a workaround for cases where
847 // assembler code forgets to set section flags. FIXME: Perhaps
848 // there should be an option to control this.
849 Output_section
* os
= NULL
;
851 if (lookup_type
== elfcpp::SHT_PROGBITS
)
855 Output_section
* same_name
= this->find_output_section(name
);
856 if (same_name
!= NULL
857 && (same_name
->type() == elfcpp::SHT_PROGBITS
858 || same_name
->type() == elfcpp::SHT_INIT_ARRAY
859 || same_name
->type() == elfcpp::SHT_FINI_ARRAY
860 || same_name
->type() == elfcpp::SHT_PREINIT_ARRAY
)
861 && (same_name
->flags() & elfcpp::SHF_TLS
) == 0)
864 else if ((flags
& elfcpp::SHF_TLS
) == 0)
866 elfcpp::Elf_Xword zero_flags
= 0;
867 const Key
zero_key(name_key
, std::make_pair(lookup_type
,
869 Section_name_map::iterator p
=
870 this->section_name_map_
.find(zero_key
);
871 if (p
!= this->section_name_map_
.end())
877 os
= this->make_output_section(name
, type
, flags
, order
, is_relro
);
879 ins
.first
->second
= os
;
884 // Returns TRUE iff NAME (an input section from RELOBJ) will
885 // be mapped to an output section that should be KEPT.
888 Layout::keep_input_section(const Relobj
* relobj
, const char* name
)
890 if (! this->script_options_
->saw_sections_clause())
893 Script_sections
* ss
= this->script_options_
->script_sections();
894 const char* file_name
= relobj
== NULL
? NULL
: relobj
->name().c_str();
895 Output_section
** output_section_slot
;
896 Script_sections::Section_type script_section_type
;
899 name
= ss
->output_section_name(file_name
, name
, &output_section_slot
,
900 &script_section_type
, &keep
);
901 return name
!= NULL
&& keep
;
904 // Clear the input section flags that should not be copied to the
908 Layout::get_output_section_flags(elfcpp::Elf_Xword input_section_flags
)
910 // Some flags in the input section should not be automatically
911 // copied to the output section.
912 input_section_flags
&= ~ (elfcpp::SHF_INFO_LINK
915 | elfcpp::SHF_STRINGS
);
917 // We only clear the SHF_LINK_ORDER flag in for
918 // a non-relocatable link.
919 if (!parameters
->options().relocatable())
920 input_section_flags
&= ~elfcpp::SHF_LINK_ORDER
;
922 return input_section_flags
;
925 // Pick the output section to use for section NAME, in input file
926 // RELOBJ, with type TYPE and flags FLAGS. RELOBJ may be NULL for a
927 // linker created section. IS_INPUT_SECTION is true if we are
928 // choosing an output section for an input section found in a input
929 // file. ORDER is where this section should appear in the output
930 // sections. IS_RELRO is true for a relro section. This will return
931 // NULL if the input section should be discarded.
934 Layout::choose_output_section(const Relobj
* relobj
, const char* name
,
935 elfcpp::Elf_Word type
, elfcpp::Elf_Xword flags
,
936 bool is_input_section
, Output_section_order order
,
939 // We should not see any input sections after we have attached
940 // sections to segments.
941 gold_assert(!is_input_section
|| !this->sections_are_attached_
);
943 flags
= this->get_output_section_flags(flags
);
945 if (this->script_options_
->saw_sections_clause())
947 // We are using a SECTIONS clause, so the output section is
948 // chosen based only on the name.
950 Script_sections
* ss
= this->script_options_
->script_sections();
951 const char* file_name
= relobj
== NULL
? NULL
: relobj
->name().c_str();
952 Output_section
** output_section_slot
;
953 Script_sections::Section_type script_section_type
;
954 const char* orig_name
= name
;
956 name
= ss
->output_section_name(file_name
, name
, &output_section_slot
,
957 &script_section_type
, &keep
);
961 gold_debug(DEBUG_SCRIPT
, _("Unable to create output section '%s' "
962 "because it is not allowed by the "
963 "SECTIONS clause of the linker script"),
965 // The SECTIONS clause says to discard this input section.
969 // We can only handle script section types ST_NONE and ST_NOLOAD.
970 switch (script_section_type
)
972 case Script_sections::ST_NONE
:
974 case Script_sections::ST_NOLOAD
:
975 flags
&= elfcpp::SHF_ALLOC
;
981 // If this is an orphan section--one not mentioned in the linker
982 // script--then OUTPUT_SECTION_SLOT will be NULL, and we do the
983 // default processing below.
985 if (output_section_slot
!= NULL
)
987 if (*output_section_slot
!= NULL
)
989 (*output_section_slot
)->update_flags_for_input_section(flags
);
990 return *output_section_slot
;
993 // We don't put sections found in the linker script into
994 // SECTION_NAME_MAP_. That keeps us from getting confused
995 // if an orphan section is mapped to a section with the same
996 // name as one in the linker script.
998 name
= this->namepool_
.add(name
, false, NULL
);
1000 Output_section
* os
= this->make_output_section(name
, type
, flags
,
1003 os
->set_found_in_sections_clause();
1005 // Special handling for NOLOAD sections.
1006 if (script_section_type
== Script_sections::ST_NOLOAD
)
1008 os
->set_is_noload();
1010 // The constructor of Output_section sets addresses of non-ALLOC
1011 // sections to 0 by default. We don't want that for NOLOAD
1012 // sections even if they have no SHF_ALLOC flag.
1013 if ((os
->flags() & elfcpp::SHF_ALLOC
) == 0
1014 && os
->is_address_valid())
1016 gold_assert(os
->address() == 0
1017 && !os
->is_offset_valid()
1018 && !os
->is_data_size_valid());
1019 os
->reset_address_and_file_offset();
1023 *output_section_slot
= os
;
1028 // FIXME: Handle SHF_OS_NONCONFORMING somewhere.
1030 size_t len
= strlen(name
);
1031 char* uncompressed_name
= NULL
;
1033 // Compressed debug sections should be mapped to the corresponding
1034 // uncompressed section.
1035 if (is_compressed_debug_section(name
))
1037 uncompressed_name
= new char[len
];
1038 uncompressed_name
[0] = '.';
1039 gold_assert(name
[0] == '.' && name
[1] == 'z');
1040 strncpy(&uncompressed_name
[1], &name
[2], len
- 2);
1041 uncompressed_name
[len
- 1] = '\0';
1043 name
= uncompressed_name
;
1046 // Turn NAME from the name of the input section into the name of the
1048 if (is_input_section
1049 && !this->script_options_
->saw_sections_clause()
1050 && !parameters
->options().relocatable())
1052 const char *orig_name
= name
;
1053 name
= parameters
->target().output_section_name(relobj
, name
, &len
);
1055 name
= Layout::output_section_name(relobj
, orig_name
, &len
);
1058 Stringpool::Key name_key
;
1059 name
= this->namepool_
.add_with_length(name
, len
, true, &name_key
);
1061 if (uncompressed_name
!= NULL
)
1062 delete[] uncompressed_name
;
1064 // Find or make the output section. The output section is selected
1065 // based on the section name, type, and flags.
1066 return this->get_output_section(name
, name_key
, type
, flags
, order
, is_relro
);
1069 // For incremental links, record the initial fixed layout of a section
1070 // from the base file, and return a pointer to the Output_section.
1072 template<int size
, bool big_endian
>
1074 Layout::init_fixed_output_section(const char* name
,
1075 elfcpp::Shdr
<size
, big_endian
>& shdr
)
1077 unsigned int sh_type
= shdr
.get_sh_type();
1079 // We preserve the layout of PROGBITS, NOBITS, INIT_ARRAY, FINI_ARRAY,
1080 // PRE_INIT_ARRAY, and NOTE sections.
1081 // All others will be created from scratch and reallocated.
1082 if (!can_incremental_update(sh_type
))
1085 // If we're generating a .gdb_index section, we need to regenerate
1087 if (parameters
->options().gdb_index()
1088 && sh_type
== elfcpp::SHT_PROGBITS
1089 && strcmp(name
, ".gdb_index") == 0)
1092 typename
elfcpp::Elf_types
<size
>::Elf_Addr sh_addr
= shdr
.get_sh_addr();
1093 typename
elfcpp::Elf_types
<size
>::Elf_Off sh_offset
= shdr
.get_sh_offset();
1094 typename
elfcpp::Elf_types
<size
>::Elf_WXword sh_size
= shdr
.get_sh_size();
1095 typename
elfcpp::Elf_types
<size
>::Elf_WXword sh_flags
= shdr
.get_sh_flags();
1096 typename
elfcpp::Elf_types
<size
>::Elf_WXword sh_addralign
=
1097 shdr
.get_sh_addralign();
1099 // Make the output section.
1100 Stringpool::Key name_key
;
1101 name
= this->namepool_
.add(name
, true, &name_key
);
1102 Output_section
* os
= this->get_output_section(name
, name_key
, sh_type
,
1103 sh_flags
, ORDER_INVALID
, false);
1104 os
->set_fixed_layout(sh_addr
, sh_offset
, sh_size
, sh_addralign
);
1105 if (sh_type
!= elfcpp::SHT_NOBITS
)
1106 this->free_list_
.remove(sh_offset
, sh_offset
+ sh_size
);
1110 // Return the index by which an input section should be ordered. This
1111 // is used to sort some .text sections, for compatibility with GNU ld.
1114 Layout::special_ordering_of_input_section(const char* name
)
1116 // The GNU linker has some special handling for some sections that
1117 // wind up in the .text section. Sections that start with these
1118 // prefixes must appear first, and must appear in the order listed
1120 static const char* const text_section_sort
[] =
1129 i
< sizeof(text_section_sort
) / sizeof(text_section_sort
[0]);
1131 if (is_prefix_of(text_section_sort
[i
], name
))
1137 // Return the output section to use for input section SHNDX, with name
1138 // NAME, with header HEADER, from object OBJECT. RELOC_SHNDX is the
1139 // index of a relocation section which applies to this section, or 0
1140 // if none, or -1U if more than one. RELOC_TYPE is the type of the
1141 // relocation section if there is one. Set *OFF to the offset of this
1142 // input section without the output section. Return NULL if the
1143 // section should be discarded. Set *OFF to -1 if the section
1144 // contents should not be written directly to the output file, but
1145 // will instead receive special handling.
1147 template<int size
, bool big_endian
>
1149 Layout::layout(Sized_relobj_file
<size
, big_endian
>* object
, unsigned int shndx
,
1150 const char* name
, const elfcpp::Shdr
<size
, big_endian
>& shdr
,
1151 unsigned int reloc_shndx
, unsigned int, off_t
* off
)
1155 if (!this->include_section(object
, name
, shdr
))
1158 elfcpp::Elf_Word sh_type
= shdr
.get_sh_type();
1160 // In a relocatable link a grouped section must not be combined with
1161 // any other sections.
1163 if (parameters
->options().relocatable()
1164 && (shdr
.get_sh_flags() & elfcpp::SHF_GROUP
) != 0)
1166 name
= this->namepool_
.add(name
, true, NULL
);
1167 os
= this->make_output_section(name
, sh_type
, shdr
.get_sh_flags(),
1168 ORDER_INVALID
, false);
1172 // Plugins can choose to place one or more subsets of sections in
1173 // unique segments and this is done by mapping these section subsets
1174 // to unique output sections. Check if this section needs to be
1175 // remapped to a unique output section.
1176 Section_segment_map::iterator it
1177 = this->section_segment_map_
.find(Const_section_id(object
, shndx
));
1178 if (it
== this->section_segment_map_
.end())
1180 os
= this->choose_output_section(object
, name
, sh_type
,
1181 shdr
.get_sh_flags(), true,
1182 ORDER_INVALID
, false);
1186 // We know the name of the output section, directly call
1187 // get_output_section here by-passing choose_output_section.
1188 elfcpp::Elf_Xword flags
1189 = this->get_output_section_flags(shdr
.get_sh_flags());
1191 const char* os_name
= it
->second
->name
;
1192 Stringpool::Key name_key
;
1193 os_name
= this->namepool_
.add(os_name
, true, &name_key
);
1194 os
= this->get_output_section(os_name
, name_key
, sh_type
, flags
,
1195 ORDER_INVALID
, false);
1196 if (!os
->is_unique_segment())
1198 os
->set_is_unique_segment();
1199 os
->set_extra_segment_flags(it
->second
->flags
);
1200 os
->set_segment_alignment(it
->second
->align
);
1207 // By default the GNU linker sorts input sections whose names match
1208 // .ctors.*, .dtors.*, .init_array.*, or .fini_array.*. The
1209 // sections are sorted by name. This is used to implement
1210 // constructor priority ordering. We are compatible. When we put
1211 // .ctor sections in .init_array and .dtor sections in .fini_array,
1212 // we must also sort plain .ctor and .dtor sections.
1213 if (!this->script_options_
->saw_sections_clause()
1214 && !parameters
->options().relocatable()
1215 && (is_prefix_of(".ctors.", name
)
1216 || is_prefix_of(".dtors.", name
)
1217 || is_prefix_of(".init_array.", name
)
1218 || is_prefix_of(".fini_array.", name
)
1219 || (parameters
->options().ctors_in_init_array()
1220 && (strcmp(name
, ".ctors") == 0
1221 || strcmp(name
, ".dtors") == 0))))
1222 os
->set_must_sort_attached_input_sections();
1224 // By default the GNU linker sorts some special text sections ahead
1225 // of others. We are compatible.
1226 if (parameters
->options().text_reorder()
1227 && !this->script_options_
->saw_sections_clause()
1228 && !this->is_section_ordering_specified()
1229 && !parameters
->options().relocatable()
1230 && Layout::special_ordering_of_input_section(name
) >= 0)
1231 os
->set_must_sort_attached_input_sections();
1233 // If this is a .ctors or .ctors.* section being mapped to a
1234 // .init_array section, or a .dtors or .dtors.* section being mapped
1235 // to a .fini_array section, we will need to reverse the words if
1236 // there is more than one. Record this section for later. See
1237 // ctors_sections_in_init_array above.
1238 if (!this->script_options_
->saw_sections_clause()
1239 && !parameters
->options().relocatable()
1240 && shdr
.get_sh_size() > size
/ 8
1241 && (((strcmp(name
, ".ctors") == 0
1242 || is_prefix_of(".ctors.", name
))
1243 && strcmp(os
->name(), ".init_array") == 0)
1244 || ((strcmp(name
, ".dtors") == 0
1245 || is_prefix_of(".dtors.", name
))
1246 && strcmp(os
->name(), ".fini_array") == 0)))
1247 ctors_sections_in_init_array
.insert(Section_id(object
, shndx
));
1249 // FIXME: Handle SHF_LINK_ORDER somewhere.
1251 elfcpp::Elf_Xword orig_flags
= os
->flags();
1253 *off
= os
->add_input_section(this, object
, shndx
, name
, shdr
, reloc_shndx
,
1254 this->script_options_
->saw_sections_clause());
1256 // If the flags changed, we may have to change the order.
1257 if ((orig_flags
& elfcpp::SHF_ALLOC
) != 0)
1259 orig_flags
&= (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
);
1260 elfcpp::Elf_Xword new_flags
=
1261 os
->flags() & (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
);
1262 if (orig_flags
!= new_flags
)
1263 os
->set_order(this->default_section_order(os
, false));
1266 this->have_added_input_section_
= true;
1271 // Maps section SECN to SEGMENT s.
1273 Layout::insert_section_segment_map(Const_section_id secn
,
1274 Unique_segment_info
*s
)
1276 gold_assert(this->unique_segment_for_sections_specified_
);
1277 this->section_segment_map_
[secn
] = s
;
1280 // Handle a relocation section when doing a relocatable link.
1282 template<int size
, bool big_endian
>
1284 Layout::layout_reloc(Sized_relobj_file
<size
, big_endian
>* object
,
1286 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
1287 Output_section
* data_section
,
1288 Relocatable_relocs
* rr
)
1290 gold_assert(parameters
->options().relocatable()
1291 || parameters
->options().emit_relocs());
1293 int sh_type
= shdr
.get_sh_type();
1296 if (sh_type
== elfcpp::SHT_REL
)
1298 else if (sh_type
== elfcpp::SHT_RELA
)
1302 name
+= data_section
->name();
1304 // In a relocatable link relocs for a grouped section must not be
1305 // combined with other reloc sections.
1307 if (!parameters
->options().relocatable()
1308 || (data_section
->flags() & elfcpp::SHF_GROUP
) == 0)
1309 os
= this->choose_output_section(object
, name
.c_str(), sh_type
,
1310 shdr
.get_sh_flags(), false,
1311 ORDER_INVALID
, false);
1314 const char* n
= this->namepool_
.add(name
.c_str(), true, NULL
);
1315 os
= this->make_output_section(n
, sh_type
, shdr
.get_sh_flags(),
1316 ORDER_INVALID
, false);
1319 os
->set_should_link_to_symtab();
1320 os
->set_info_section(data_section
);
1322 Output_section_data
* posd
;
1323 if (sh_type
== elfcpp::SHT_REL
)
1325 os
->set_entsize(elfcpp::Elf_sizes
<size
>::rel_size
);
1326 posd
= new Output_relocatable_relocs
<elfcpp::SHT_REL
,
1330 else if (sh_type
== elfcpp::SHT_RELA
)
1332 os
->set_entsize(elfcpp::Elf_sizes
<size
>::rela_size
);
1333 posd
= new Output_relocatable_relocs
<elfcpp::SHT_RELA
,
1340 os
->add_output_section_data(posd
);
1341 rr
->set_output_data(posd
);
1346 // Handle a group section when doing a relocatable link.
1348 template<int size
, bool big_endian
>
1350 Layout::layout_group(Symbol_table
* symtab
,
1351 Sized_relobj_file
<size
, big_endian
>* object
,
1353 const char* group_section_name
,
1354 const char* signature
,
1355 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
1356 elfcpp::Elf_Word flags
,
1357 std::vector
<unsigned int>* shndxes
)
1359 gold_assert(parameters
->options().relocatable());
1360 gold_assert(shdr
.get_sh_type() == elfcpp::SHT_GROUP
);
1361 group_section_name
= this->namepool_
.add(group_section_name
, true, NULL
);
1362 Output_section
* os
= this->make_output_section(group_section_name
,
1364 shdr
.get_sh_flags(),
1365 ORDER_INVALID
, false);
1367 // We need to find a symbol with the signature in the symbol table.
1368 // If we don't find one now, we need to look again later.
1369 Symbol
* sym
= symtab
->lookup(signature
, NULL
);
1371 os
->set_info_symndx(sym
);
1374 // Reserve some space to minimize reallocations.
1375 if (this->group_signatures_
.empty())
1376 this->group_signatures_
.reserve(this->number_of_input_files_
* 16);
1378 // We will wind up using a symbol whose name is the signature.
1379 // So just put the signature in the symbol name pool to save it.
1380 signature
= symtab
->canonicalize_name(signature
);
1381 this->group_signatures_
.push_back(Group_signature(os
, signature
));
1384 os
->set_should_link_to_symtab();
1387 section_size_type entry_count
=
1388 convert_to_section_size_type(shdr
.get_sh_size() / 4);
1389 Output_section_data
* posd
=
1390 new Output_data_group
<size
, big_endian
>(object
, entry_count
, flags
,
1392 os
->add_output_section_data(posd
);
1395 // Special GNU handling of sections name .eh_frame. They will
1396 // normally hold exception frame data as defined by the C++ ABI
1397 // (http://codesourcery.com/cxx-abi/).
1399 template<int size
, bool big_endian
>
1401 Layout::layout_eh_frame(Sized_relobj_file
<size
, big_endian
>* object
,
1402 const unsigned char* symbols
,
1404 const unsigned char* symbol_names
,
1405 off_t symbol_names_size
,
1407 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
1408 unsigned int reloc_shndx
, unsigned int reloc_type
,
1411 gold_assert(shdr
.get_sh_type() == elfcpp::SHT_PROGBITS
1412 || shdr
.get_sh_type() == elfcpp::SHT_X86_64_UNWIND
);
1413 gold_assert((shdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) != 0);
1415 Output_section
* os
= this->make_eh_frame_section(object
);
1419 gold_assert(this->eh_frame_section_
== os
);
1421 elfcpp::Elf_Xword orig_flags
= os
->flags();
1423 if (!parameters
->incremental()
1424 && this->eh_frame_data_
->add_ehframe_input_section(object
,
1433 os
->update_flags_for_input_section(shdr
.get_sh_flags());
1435 // A writable .eh_frame section is a RELRO section.
1436 if ((orig_flags
& (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
))
1437 != (os
->flags() & (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
)))
1440 os
->set_order(ORDER_RELRO
);
1443 // We found a .eh_frame section we are going to optimize, so now
1444 // we can add the set of optimized sections to the output
1445 // section. We need to postpone adding this until we've found a
1446 // section we can optimize so that the .eh_frame section in
1447 // crtbegin.o winds up at the start of the output section.
1448 if (!this->added_eh_frame_data_
)
1450 os
->add_output_section_data(this->eh_frame_data_
);
1451 this->added_eh_frame_data_
= true;
1457 // We couldn't handle this .eh_frame section for some reason.
1458 // Add it as a normal section.
1459 bool saw_sections_clause
= this->script_options_
->saw_sections_clause();
1460 *off
= os
->add_input_section(this, object
, shndx
, ".eh_frame", shdr
,
1461 reloc_shndx
, saw_sections_clause
);
1462 this->have_added_input_section_
= true;
1464 if ((orig_flags
& (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
))
1465 != (os
->flags() & (elfcpp::SHF_WRITE
| elfcpp::SHF_EXECINSTR
)))
1466 os
->set_order(this->default_section_order(os
, false));
1472 // Create and return the magic .eh_frame section. Create
1473 // .eh_frame_hdr also if appropriate. OBJECT is the object with the
1474 // input .eh_frame section; it may be NULL.
1477 Layout::make_eh_frame_section(const Relobj
* object
)
1479 // FIXME: On x86_64, this could use SHT_X86_64_UNWIND rather than
1481 Output_section
* os
= this->choose_output_section(object
, ".eh_frame",
1482 elfcpp::SHT_PROGBITS
,
1483 elfcpp::SHF_ALLOC
, false,
1484 ORDER_EHFRAME
, false);
1488 if (this->eh_frame_section_
== NULL
)
1490 this->eh_frame_section_
= os
;
1491 this->eh_frame_data_
= new Eh_frame();
1493 // For incremental linking, we do not optimize .eh_frame sections
1494 // or create a .eh_frame_hdr section.
1495 if (parameters
->options().eh_frame_hdr() && !parameters
->incremental())
1497 Output_section
* hdr_os
=
1498 this->choose_output_section(NULL
, ".eh_frame_hdr",
1499 elfcpp::SHT_PROGBITS
,
1500 elfcpp::SHF_ALLOC
, false,
1501 ORDER_EHFRAME
, false);
1505 Eh_frame_hdr
* hdr_posd
= new Eh_frame_hdr(os
,
1506 this->eh_frame_data_
);
1507 hdr_os
->add_output_section_data(hdr_posd
);
1509 hdr_os
->set_after_input_sections();
1511 if (!this->script_options_
->saw_phdrs_clause())
1513 Output_segment
* hdr_oseg
;
1514 hdr_oseg
= this->make_output_segment(elfcpp::PT_GNU_EH_FRAME
,
1516 hdr_oseg
->add_output_section_to_nonload(hdr_os
,
1520 this->eh_frame_data_
->set_eh_frame_hdr(hdr_posd
);
1528 // Add an exception frame for a PLT. This is called from target code.
1531 Layout::add_eh_frame_for_plt(Output_data
* plt
, const unsigned char* cie_data
,
1532 size_t cie_length
, const unsigned char* fde_data
,
1535 if (parameters
->incremental())
1537 // FIXME: Maybe this could work some day....
1540 Output_section
* os
= this->make_eh_frame_section(NULL
);
1543 this->eh_frame_data_
->add_ehframe_for_plt(plt
, cie_data
, cie_length
,
1544 fde_data
, fde_length
);
1545 if (!this->added_eh_frame_data_
)
1547 os
->add_output_section_data(this->eh_frame_data_
);
1548 this->added_eh_frame_data_
= true;
1552 // Scan a .debug_info or .debug_types section, and add summary
1553 // information to the .gdb_index section.
1555 template<int size
, bool big_endian
>
1557 Layout::add_to_gdb_index(bool is_type_unit
,
1558 Sized_relobj
<size
, big_endian
>* object
,
1559 const unsigned char* symbols
,
1562 unsigned int reloc_shndx
,
1563 unsigned int reloc_type
)
1565 if (this->gdb_index_data_
== NULL
)
1567 Output_section
* os
= this->choose_output_section(NULL
, ".gdb_index",
1568 elfcpp::SHT_PROGBITS
, 0,
1569 false, ORDER_INVALID
,
1574 this->gdb_index_data_
= new Gdb_index(os
);
1575 os
->add_output_section_data(this->gdb_index_data_
);
1576 os
->set_after_input_sections();
1579 this->gdb_index_data_
->scan_debug_info(is_type_unit
, object
, symbols
,
1580 symbols_size
, shndx
, reloc_shndx
,
1584 // Add POSD to an output section using NAME, TYPE, and FLAGS. Return
1585 // the output section.
1588 Layout::add_output_section_data(const char* name
, elfcpp::Elf_Word type
,
1589 elfcpp::Elf_Xword flags
,
1590 Output_section_data
* posd
,
1591 Output_section_order order
, bool is_relro
)
1593 Output_section
* os
= this->choose_output_section(NULL
, name
, type
, flags
,
1594 false, order
, is_relro
);
1596 os
->add_output_section_data(posd
);
1600 // Map section flags to segment flags.
1603 Layout::section_flags_to_segment(elfcpp::Elf_Xword flags
)
1605 elfcpp::Elf_Word ret
= elfcpp::PF_R
;
1606 if ((flags
& elfcpp::SHF_WRITE
) != 0)
1607 ret
|= elfcpp::PF_W
;
1608 if ((flags
& elfcpp::SHF_EXECINSTR
) != 0)
1609 ret
|= elfcpp::PF_X
;
1613 // Make a new Output_section, and attach it to segments as
1614 // appropriate. ORDER is the order in which this section should
1615 // appear in the output segment. IS_RELRO is true if this is a relro
1616 // (read-only after relocations) section.
1619 Layout::make_output_section(const char* name
, elfcpp::Elf_Word type
,
1620 elfcpp::Elf_Xword flags
,
1621 Output_section_order order
, bool is_relro
)
1624 if ((flags
& elfcpp::SHF_ALLOC
) == 0
1625 && strcmp(parameters
->options().compress_debug_sections(), "none") != 0
1626 && is_compressible_debug_section(name
))
1627 os
= new Output_compressed_section(¶meters
->options(), name
, type
,
1629 else if ((flags
& elfcpp::SHF_ALLOC
) == 0
1630 && parameters
->options().strip_debug_non_line()
1631 && strcmp(".debug_abbrev", name
) == 0)
1633 os
= this->debug_abbrev_
= new Output_reduced_debug_abbrev_section(
1635 if (this->debug_info_
)
1636 this->debug_info_
->set_abbreviations(this->debug_abbrev_
);
1638 else if ((flags
& elfcpp::SHF_ALLOC
) == 0
1639 && parameters
->options().strip_debug_non_line()
1640 && strcmp(".debug_info", name
) == 0)
1642 os
= this->debug_info_
= new Output_reduced_debug_info_section(
1644 if (this->debug_abbrev_
)
1645 this->debug_info_
->set_abbreviations(this->debug_abbrev_
);
1649 // Sometimes .init_array*, .preinit_array* and .fini_array* do
1650 // not have correct section types. Force them here.
1651 if (type
== elfcpp::SHT_PROGBITS
)
1653 if (is_prefix_of(".init_array", name
))
1654 type
= elfcpp::SHT_INIT_ARRAY
;
1655 else if (is_prefix_of(".preinit_array", name
))
1656 type
= elfcpp::SHT_PREINIT_ARRAY
;
1657 else if (is_prefix_of(".fini_array", name
))
1658 type
= elfcpp::SHT_FINI_ARRAY
;
1661 // FIXME: const_cast is ugly.
1662 Target
* target
= const_cast<Target
*>(¶meters
->target());
1663 os
= target
->make_output_section(name
, type
, flags
);
1666 // With -z relro, we have to recognize the special sections by name.
1667 // There is no other way.
1668 bool is_relro_local
= false;
1669 if (!this->script_options_
->saw_sections_clause()
1670 && parameters
->options().relro()
1671 && (flags
& elfcpp::SHF_ALLOC
) != 0
1672 && (flags
& elfcpp::SHF_WRITE
) != 0)
1674 if (type
== elfcpp::SHT_PROGBITS
)
1676 if ((flags
& elfcpp::SHF_TLS
) != 0)
1678 else if (strcmp(name
, ".data.rel.ro") == 0)
1680 else if (strcmp(name
, ".data.rel.ro.local") == 0)
1683 is_relro_local
= true;
1685 else if (strcmp(name
, ".ctors") == 0
1686 || strcmp(name
, ".dtors") == 0
1687 || strcmp(name
, ".jcr") == 0)
1690 else if (type
== elfcpp::SHT_INIT_ARRAY
1691 || type
== elfcpp::SHT_FINI_ARRAY
1692 || type
== elfcpp::SHT_PREINIT_ARRAY
)
1699 if (order
== ORDER_INVALID
&& (flags
& elfcpp::SHF_ALLOC
) != 0)
1700 order
= this->default_section_order(os
, is_relro_local
);
1702 os
->set_order(order
);
1704 parameters
->target().new_output_section(os
);
1706 this->section_list_
.push_back(os
);
1708 // The GNU linker by default sorts some sections by priority, so we
1709 // do the same. We need to know that this might happen before we
1710 // attach any input sections.
1711 if (!this->script_options_
->saw_sections_clause()
1712 && !parameters
->options().relocatable()
1713 && (strcmp(name
, ".init_array") == 0
1714 || strcmp(name
, ".fini_array") == 0
1715 || (!parameters
->options().ctors_in_init_array()
1716 && (strcmp(name
, ".ctors") == 0
1717 || strcmp(name
, ".dtors") == 0))))
1718 os
->set_may_sort_attached_input_sections();
1720 // The GNU linker by default sorts .text.{unlikely,exit,startup,hot}
1721 // sections before other .text sections. We are compatible. We
1722 // need to know that this might happen before we attach any input
1724 if (parameters
->options().text_reorder()
1725 && !this->script_options_
->saw_sections_clause()
1726 && !this->is_section_ordering_specified()
1727 && !parameters
->options().relocatable()
1728 && strcmp(name
, ".text") == 0)
1729 os
->set_may_sort_attached_input_sections();
1731 // GNU linker sorts section by name with --sort-section=name.
1732 if (strcmp(parameters
->options().sort_section(), "name") == 0)
1733 os
->set_must_sort_attached_input_sections();
1735 // Check for .stab*str sections, as .stab* sections need to link to
1737 if (type
== elfcpp::SHT_STRTAB
1738 && !this->have_stabstr_section_
1739 && strncmp(name
, ".stab", 5) == 0
1740 && strcmp(name
+ strlen(name
) - 3, "str") == 0)
1741 this->have_stabstr_section_
= true;
1743 // During a full incremental link, we add patch space to most
1744 // PROGBITS and NOBITS sections. Flag those that may be
1745 // arbitrarily padded.
1746 if ((type
== elfcpp::SHT_PROGBITS
|| type
== elfcpp::SHT_NOBITS
)
1747 && order
!= ORDER_INTERP
1748 && order
!= ORDER_INIT
1749 && order
!= ORDER_PLT
1750 && order
!= ORDER_FINI
1751 && order
!= ORDER_RELRO_LAST
1752 && order
!= ORDER_NON_RELRO_FIRST
1753 && strcmp(name
, ".eh_frame") != 0
1754 && strcmp(name
, ".ctors") != 0
1755 && strcmp(name
, ".dtors") != 0
1756 && strcmp(name
, ".jcr") != 0)
1758 os
->set_is_patch_space_allowed();
1760 // Certain sections require "holes" to be filled with
1761 // specific fill patterns. These fill patterns may have
1762 // a minimum size, so we must prevent allocations from the
1763 // free list that leave a hole smaller than the minimum.
1764 if (strcmp(name
, ".debug_info") == 0)
1765 os
->set_free_space_fill(new Output_fill_debug_info(false));
1766 else if (strcmp(name
, ".debug_types") == 0)
1767 os
->set_free_space_fill(new Output_fill_debug_info(true));
1768 else if (strcmp(name
, ".debug_line") == 0)
1769 os
->set_free_space_fill(new Output_fill_debug_line());
1772 // If we have already attached the sections to segments, then we
1773 // need to attach this one now. This happens for sections created
1774 // directly by the linker.
1775 if (this->sections_are_attached_
)
1776 this->attach_section_to_segment(¶meters
->target(), os
);
1781 // Return the default order in which a section should be placed in an
1782 // output segment. This function captures a lot of the ideas in
1783 // ld/scripttempl/elf.sc in the GNU linker. Note that the order of a
1784 // linker created section is normally set when the section is created;
1785 // this function is used for input sections.
1787 Output_section_order
1788 Layout::default_section_order(Output_section
* os
, bool is_relro_local
)
1790 gold_assert((os
->flags() & elfcpp::SHF_ALLOC
) != 0);
1791 bool is_write
= (os
->flags() & elfcpp::SHF_WRITE
) != 0;
1792 bool is_execinstr
= (os
->flags() & elfcpp::SHF_EXECINSTR
) != 0;
1793 bool is_bss
= false;
1798 case elfcpp::SHT_PROGBITS
:
1800 case elfcpp::SHT_NOBITS
:
1803 case elfcpp::SHT_RELA
:
1804 case elfcpp::SHT_REL
:
1806 return ORDER_DYNAMIC_RELOCS
;
1808 case elfcpp::SHT_HASH
:
1809 case elfcpp::SHT_DYNAMIC
:
1810 case elfcpp::SHT_SHLIB
:
1811 case elfcpp::SHT_DYNSYM
:
1812 case elfcpp::SHT_GNU_HASH
:
1813 case elfcpp::SHT_GNU_verdef
:
1814 case elfcpp::SHT_GNU_verneed
:
1815 case elfcpp::SHT_GNU_versym
:
1817 return ORDER_DYNAMIC_LINKER
;
1819 case elfcpp::SHT_NOTE
:
1820 return is_write
? ORDER_RW_NOTE
: ORDER_RO_NOTE
;
1823 if ((os
->flags() & elfcpp::SHF_TLS
) != 0)
1824 return is_bss
? ORDER_TLS_BSS
: ORDER_TLS_DATA
;
1826 if (!is_bss
&& !is_write
)
1830 if (strcmp(os
->name(), ".init") == 0)
1832 else if (strcmp(os
->name(), ".fini") == 0)
1835 return is_execinstr
? ORDER_TEXT
: ORDER_READONLY
;
1839 return is_relro_local
? ORDER_RELRO_LOCAL
: ORDER_RELRO
;
1841 if (os
->is_small_section())
1842 return is_bss
? ORDER_SMALL_BSS
: ORDER_SMALL_DATA
;
1843 if (os
->is_large_section())
1844 return is_bss
? ORDER_LARGE_BSS
: ORDER_LARGE_DATA
;
1846 return is_bss
? ORDER_BSS
: ORDER_DATA
;
1849 // Attach output sections to segments. This is called after we have
1850 // seen all the input sections.
1853 Layout::attach_sections_to_segments(const Target
* target
)
1855 for (Section_list::iterator p
= this->section_list_
.begin();
1856 p
!= this->section_list_
.end();
1858 this->attach_section_to_segment(target
, *p
);
1860 this->sections_are_attached_
= true;
1863 // Attach an output section to a segment.
1866 Layout::attach_section_to_segment(const Target
* target
, Output_section
* os
)
1868 if ((os
->flags() & elfcpp::SHF_ALLOC
) == 0)
1869 this->unattached_section_list_
.push_back(os
);
1871 this->attach_allocated_section_to_segment(target
, os
);
1874 // Attach an allocated output section to a segment.
1877 Layout::attach_allocated_section_to_segment(const Target
* target
,
1880 elfcpp::Elf_Xword flags
= os
->flags();
1881 gold_assert((flags
& elfcpp::SHF_ALLOC
) != 0);
1883 if (parameters
->options().relocatable())
1886 // If we have a SECTIONS clause, we can't handle the attachment to
1887 // segments until after we've seen all the sections.
1888 if (this->script_options_
->saw_sections_clause())
1891 gold_assert(!this->script_options_
->saw_phdrs_clause());
1893 // This output section goes into a PT_LOAD segment.
1895 elfcpp::Elf_Word seg_flags
= Layout::section_flags_to_segment(flags
);
1897 // If this output section's segment has extra flags that need to be set,
1898 // coming from a linker plugin, do that.
1899 seg_flags
|= os
->extra_segment_flags();
1901 // Check for --section-start.
1903 bool is_address_set
= parameters
->options().section_start(os
->name(), &addr
);
1905 // In general the only thing we really care about for PT_LOAD
1906 // segments is whether or not they are writable or executable,
1907 // so that is how we search for them.
1908 // Large data sections also go into their own PT_LOAD segment.
1909 // People who need segments sorted on some other basis will
1910 // have to use a linker script.
1912 Segment_list::const_iterator p
;
1913 if (!os
->is_unique_segment())
1915 for (p
= this->segment_list_
.begin();
1916 p
!= this->segment_list_
.end();
1919 if ((*p
)->type() != elfcpp::PT_LOAD
)
1921 if ((*p
)->is_unique_segment())
1923 if (!parameters
->options().omagic()
1924 && ((*p
)->flags() & elfcpp::PF_W
) != (seg_flags
& elfcpp::PF_W
))
1926 if ((target
->isolate_execinstr() || parameters
->options().rosegment())
1927 && ((*p
)->flags() & elfcpp::PF_X
) != (seg_flags
& elfcpp::PF_X
))
1929 // If -Tbss was specified, we need to separate the data and BSS
1931 if (parameters
->options().user_set_Tbss())
1933 if ((os
->type() == elfcpp::SHT_NOBITS
)
1934 == (*p
)->has_any_data_sections())
1937 if (os
->is_large_data_section() && !(*p
)->is_large_data_segment())
1942 if ((*p
)->are_addresses_set())
1945 (*p
)->add_initial_output_data(os
);
1946 (*p
)->update_flags_for_output_section(seg_flags
);
1947 (*p
)->set_addresses(addr
, addr
);
1951 (*p
)->add_output_section_to_load(this, os
, seg_flags
);
1956 if (p
== this->segment_list_
.end()
1957 || os
->is_unique_segment())
1959 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_LOAD
,
1961 if (os
->is_large_data_section())
1962 oseg
->set_is_large_data_segment();
1963 oseg
->add_output_section_to_load(this, os
, seg_flags
);
1965 oseg
->set_addresses(addr
, addr
);
1966 // Check if segment should be marked unique. For segments marked
1967 // unique by linker plugins, set the new alignment if specified.
1968 if (os
->is_unique_segment())
1970 oseg
->set_is_unique_segment();
1971 if (os
->segment_alignment() != 0)
1972 oseg
->set_minimum_p_align(os
->segment_alignment());
1976 // If we see a loadable SHT_NOTE section, we create a PT_NOTE
1978 if (os
->type() == elfcpp::SHT_NOTE
)
1980 // See if we already have an equivalent PT_NOTE segment.
1981 for (p
= this->segment_list_
.begin();
1982 p
!= segment_list_
.end();
1985 if ((*p
)->type() == elfcpp::PT_NOTE
1986 && (((*p
)->flags() & elfcpp::PF_W
)
1987 == (seg_flags
& elfcpp::PF_W
)))
1989 (*p
)->add_output_section_to_nonload(os
, seg_flags
);
1994 if (p
== this->segment_list_
.end())
1996 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_NOTE
,
1998 oseg
->add_output_section_to_nonload(os
, seg_flags
);
2002 // If we see a loadable SHF_TLS section, we create a PT_TLS
2003 // segment. There can only be one such segment.
2004 if ((flags
& elfcpp::SHF_TLS
) != 0)
2006 if (this->tls_segment_
== NULL
)
2007 this->make_output_segment(elfcpp::PT_TLS
, seg_flags
);
2008 this->tls_segment_
->add_output_section_to_nonload(os
, seg_flags
);
2011 // If -z relro is in effect, and we see a relro section, we create a
2012 // PT_GNU_RELRO segment. There can only be one such segment.
2013 if (os
->is_relro() && parameters
->options().relro())
2015 gold_assert(seg_flags
== (elfcpp::PF_R
| elfcpp::PF_W
));
2016 if (this->relro_segment_
== NULL
)
2017 this->make_output_segment(elfcpp::PT_GNU_RELRO
, seg_flags
);
2018 this->relro_segment_
->add_output_section_to_nonload(os
, seg_flags
);
2021 // If we see a section named .interp, put it into a PT_INTERP
2022 // segment. This seems broken to me, but this is what GNU ld does,
2023 // and glibc expects it.
2024 if (strcmp(os
->name(), ".interp") == 0
2025 && !this->script_options_
->saw_phdrs_clause())
2027 if (this->interp_segment_
== NULL
)
2028 this->make_output_segment(elfcpp::PT_INTERP
, seg_flags
);
2030 gold_warning(_("multiple '.interp' sections in input files "
2031 "may cause confusing PT_INTERP segment"));
2032 this->interp_segment_
->add_output_section_to_nonload(os
, seg_flags
);
2036 // Make an output section for a script.
2039 Layout::make_output_section_for_script(
2041 Script_sections::Section_type section_type
)
2043 name
= this->namepool_
.add(name
, false, NULL
);
2044 elfcpp::Elf_Xword sh_flags
= elfcpp::SHF_ALLOC
;
2045 if (section_type
== Script_sections::ST_NOLOAD
)
2047 Output_section
* os
= this->make_output_section(name
, elfcpp::SHT_PROGBITS
,
2048 sh_flags
, ORDER_INVALID
,
2050 os
->set_found_in_sections_clause();
2051 if (section_type
== Script_sections::ST_NOLOAD
)
2052 os
->set_is_noload();
2056 // Return the number of segments we expect to see.
2059 Layout::expected_segment_count() const
2061 size_t ret
= this->segment_list_
.size();
2063 // If we didn't see a SECTIONS clause in a linker script, we should
2064 // already have the complete list of segments. Otherwise we ask the
2065 // SECTIONS clause how many segments it expects, and add in the ones
2066 // we already have (PT_GNU_STACK, PT_GNU_EH_FRAME, etc.)
2068 if (!this->script_options_
->saw_sections_clause())
2072 const Script_sections
* ss
= this->script_options_
->script_sections();
2073 return ret
+ ss
->expected_segment_count(this);
2077 // Handle the .note.GNU-stack section at layout time. SEEN_GNU_STACK
2078 // is whether we saw a .note.GNU-stack section in the object file.
2079 // GNU_STACK_FLAGS is the section flags. The flags give the
2080 // protection required for stack memory. We record this in an
2081 // executable as a PT_GNU_STACK segment. If an object file does not
2082 // have a .note.GNU-stack segment, we must assume that it is an old
2083 // object. On some targets that will force an executable stack.
2086 Layout::layout_gnu_stack(bool seen_gnu_stack
, uint64_t gnu_stack_flags
,
2089 if (!seen_gnu_stack
)
2091 this->input_without_gnu_stack_note_
= true;
2092 if (parameters
->options().warn_execstack()
2093 && parameters
->target().is_default_stack_executable())
2094 gold_warning(_("%s: missing .note.GNU-stack section"
2095 " implies executable stack"),
2096 obj
->name().c_str());
2100 this->input_with_gnu_stack_note_
= true;
2101 if ((gnu_stack_flags
& elfcpp::SHF_EXECINSTR
) != 0)
2103 this->input_requires_executable_stack_
= true;
2104 if (parameters
->options().warn_execstack()
2105 || parameters
->options().is_stack_executable())
2106 gold_warning(_("%s: requires executable stack"),
2107 obj
->name().c_str());
2112 // Create automatic note sections.
2115 Layout::create_notes()
2117 this->create_gold_note();
2118 this->create_executable_stack_info();
2119 this->create_build_id();
2122 // Create the dynamic sections which are needed before we read the
2126 Layout::create_initial_dynamic_sections(Symbol_table
* symtab
)
2128 if (parameters
->doing_static_link())
2131 this->dynamic_section_
= this->choose_output_section(NULL
, ".dynamic",
2132 elfcpp::SHT_DYNAMIC
,
2134 | elfcpp::SHF_WRITE
),
2138 // A linker script may discard .dynamic, so check for NULL.
2139 if (this->dynamic_section_
!= NULL
)
2141 this->dynamic_symbol_
=
2142 symtab
->define_in_output_data("_DYNAMIC", NULL
,
2143 Symbol_table::PREDEFINED
,
2144 this->dynamic_section_
, 0, 0,
2145 elfcpp::STT_OBJECT
, elfcpp::STB_LOCAL
,
2146 elfcpp::STV_HIDDEN
, 0, false, false);
2148 this->dynamic_data_
= new Output_data_dynamic(&this->dynpool_
);
2150 this->dynamic_section_
->add_output_section_data(this->dynamic_data_
);
2154 // For each output section whose name can be represented as C symbol,
2155 // define __start and __stop symbols for the section. This is a GNU
2159 Layout::define_section_symbols(Symbol_table
* symtab
)
2161 for (Section_list::const_iterator p
= this->section_list_
.begin();
2162 p
!= this->section_list_
.end();
2165 const char* const name
= (*p
)->name();
2166 if (is_cident(name
))
2168 const std::string
name_string(name
);
2169 const std::string
start_name(cident_section_start_prefix
2171 const std::string
stop_name(cident_section_stop_prefix
2174 symtab
->define_in_output_data(start_name
.c_str(),
2176 Symbol_table::PREDEFINED
,
2182 elfcpp::STV_DEFAULT
,
2184 false, // offset_is_from_end
2185 true); // only_if_ref
2187 symtab
->define_in_output_data(stop_name
.c_str(),
2189 Symbol_table::PREDEFINED
,
2195 elfcpp::STV_DEFAULT
,
2197 true, // offset_is_from_end
2198 true); // only_if_ref
2203 // Define symbols for group signatures.
2206 Layout::define_group_signatures(Symbol_table
* symtab
)
2208 for (Group_signatures::iterator p
= this->group_signatures_
.begin();
2209 p
!= this->group_signatures_
.end();
2212 Symbol
* sym
= symtab
->lookup(p
->signature
, NULL
);
2214 p
->section
->set_info_symndx(sym
);
2217 // Force the name of the group section to the group
2218 // signature, and use the group's section symbol as the
2219 // signature symbol.
2220 if (strcmp(p
->section
->name(), p
->signature
) != 0)
2222 const char* name
= this->namepool_
.add(p
->signature
,
2224 p
->section
->set_name(name
);
2226 p
->section
->set_needs_symtab_index();
2227 p
->section
->set_info_section_symndx(p
->section
);
2231 this->group_signatures_
.clear();
2234 // Find the first read-only PT_LOAD segment, creating one if
2238 Layout::find_first_load_seg(const Target
* target
)
2240 Output_segment
* best
= NULL
;
2241 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
2242 p
!= this->segment_list_
.end();
2245 if ((*p
)->type() == elfcpp::PT_LOAD
2246 && ((*p
)->flags() & elfcpp::PF_R
) != 0
2247 && (parameters
->options().omagic()
2248 || ((*p
)->flags() & elfcpp::PF_W
) == 0)
2249 && (!target
->isolate_execinstr()
2250 || ((*p
)->flags() & elfcpp::PF_X
) == 0))
2252 if (best
== NULL
|| this->segment_precedes(*p
, best
))
2259 gold_assert(!this->script_options_
->saw_phdrs_clause());
2261 Output_segment
* load_seg
= this->make_output_segment(elfcpp::PT_LOAD
,
2266 // Save states of all current output segments. Store saved states
2267 // in SEGMENT_STATES.
2270 Layout::save_segments(Segment_states
* segment_states
)
2272 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
2273 p
!= this->segment_list_
.end();
2276 Output_segment
* segment
= *p
;
2278 Output_segment
* copy
= new Output_segment(*segment
);
2279 (*segment_states
)[segment
] = copy
;
2283 // Restore states of output segments and delete any segment not found in
2287 Layout::restore_segments(const Segment_states
* segment_states
)
2289 // Go through the segment list and remove any segment added in the
2291 this->tls_segment_
= NULL
;
2292 this->relro_segment_
= NULL
;
2293 Segment_list::iterator list_iter
= this->segment_list_
.begin();
2294 while (list_iter
!= this->segment_list_
.end())
2296 Output_segment
* segment
= *list_iter
;
2297 Segment_states::const_iterator states_iter
=
2298 segment_states
->find(segment
);
2299 if (states_iter
!= segment_states
->end())
2301 const Output_segment
* copy
= states_iter
->second
;
2302 // Shallow copy to restore states.
2305 // Also fix up TLS and RELRO segment pointers as appropriate.
2306 if (segment
->type() == elfcpp::PT_TLS
)
2307 this->tls_segment_
= segment
;
2308 else if (segment
->type() == elfcpp::PT_GNU_RELRO
)
2309 this->relro_segment_
= segment
;
2315 list_iter
= this->segment_list_
.erase(list_iter
);
2316 // This is a segment created during section layout. It should be
2317 // safe to remove it since we should have removed all pointers to it.
2323 // Clean up after relaxation so that sections can be laid out again.
2326 Layout::clean_up_after_relaxation()
2328 // Restore the segments to point state just prior to the relaxation loop.
2329 Script_sections
* script_section
= this->script_options_
->script_sections();
2330 script_section
->release_segments();
2331 this->restore_segments(this->segment_states_
);
2333 // Reset section addresses and file offsets
2334 for (Section_list::iterator p
= this->section_list_
.begin();
2335 p
!= this->section_list_
.end();
2338 (*p
)->restore_states();
2340 // If an input section changes size because of relaxation,
2341 // we need to adjust the section offsets of all input sections.
2342 // after such a section.
2343 if ((*p
)->section_offsets_need_adjustment())
2344 (*p
)->adjust_section_offsets();
2346 (*p
)->reset_address_and_file_offset();
2349 // Reset special output object address and file offsets.
2350 for (Data_list::iterator p
= this->special_output_list_
.begin();
2351 p
!= this->special_output_list_
.end();
2353 (*p
)->reset_address_and_file_offset();
2355 // A linker script may have created some output section data objects.
2356 // They are useless now.
2357 for (Output_section_data_list::const_iterator p
=
2358 this->script_output_section_data_list_
.begin();
2359 p
!= this->script_output_section_data_list_
.end();
2362 this->script_output_section_data_list_
.clear();
2364 // Special-case fill output objects are recreated each time through
2365 // the relaxation loop.
2366 this->reset_relax_output();
2370 Layout::reset_relax_output()
2372 for (Data_list::const_iterator p
= this->relax_output_list_
.begin();
2373 p
!= this->relax_output_list_
.end();
2376 this->relax_output_list_
.clear();
2379 // Prepare for relaxation.
2382 Layout::prepare_for_relaxation()
2384 // Create an relaxation debug check if in debugging mode.
2385 if (is_debugging_enabled(DEBUG_RELAXATION
))
2386 this->relaxation_debug_check_
= new Relaxation_debug_check();
2388 // Save segment states.
2389 this->segment_states_
= new Segment_states();
2390 this->save_segments(this->segment_states_
);
2392 for(Section_list::const_iterator p
= this->section_list_
.begin();
2393 p
!= this->section_list_
.end();
2395 (*p
)->save_states();
2397 if (is_debugging_enabled(DEBUG_RELAXATION
))
2398 this->relaxation_debug_check_
->check_output_data_for_reset_values(
2399 this->section_list_
, this->special_output_list_
,
2400 this->relax_output_list_
);
2402 // Also enable recording of output section data from scripts.
2403 this->record_output_section_data_from_script_
= true;
2406 // If the user set the address of the text segment, that may not be
2407 // compatible with putting the segment headers and file headers into
2408 // that segment. For isolate_execinstr() targets, it's the rodata
2409 // segment rather than text where we might put the headers.
2411 load_seg_unusable_for_headers(const Target
* target
)
2413 const General_options
& options
= parameters
->options();
2414 if (target
->isolate_execinstr())
2415 return (options
.user_set_Trodata_segment()
2416 && options
.Trodata_segment() % target
->abi_pagesize() != 0);
2418 return (options
.user_set_Ttext()
2419 && options
.Ttext() % target
->abi_pagesize() != 0);
2422 // Relaxation loop body: If target has no relaxation, this runs only once
2423 // Otherwise, the target relaxation hook is called at the end of
2424 // each iteration. If the hook returns true, it means re-layout of
2425 // section is required.
2427 // The number of segments created by a linking script without a PHDRS
2428 // clause may be affected by section sizes and alignments. There is
2429 // a remote chance that relaxation causes different number of PT_LOAD
2430 // segments are created and sections are attached to different segments.
2431 // Therefore, we always throw away all segments created during section
2432 // layout. In order to be able to restart the section layout, we keep
2433 // a copy of the segment list right before the relaxation loop and use
2434 // that to restore the segments.
2436 // PASS is the current relaxation pass number.
2437 // SYMTAB is a symbol table.
2438 // PLOAD_SEG is the address of a pointer for the load segment.
2439 // PHDR_SEG is a pointer to the PHDR segment.
2440 // SEGMENT_HEADERS points to the output segment header.
2441 // FILE_HEADER points to the output file header.
2442 // PSHNDX is the address to store the output section index.
2445 Layout::relaxation_loop_body(
2448 Symbol_table
* symtab
,
2449 Output_segment
** pload_seg
,
2450 Output_segment
* phdr_seg
,
2451 Output_segment_headers
* segment_headers
,
2452 Output_file_header
* file_header
,
2453 unsigned int* pshndx
)
2455 // If this is not the first iteration, we need to clean up after
2456 // relaxation so that we can lay out the sections again.
2458 this->clean_up_after_relaxation();
2460 // If there is a SECTIONS clause, put all the input sections into
2461 // the required order.
2462 Output_segment
* load_seg
;
2463 if (this->script_options_
->saw_sections_clause())
2464 load_seg
= this->set_section_addresses_from_script(symtab
);
2465 else if (parameters
->options().relocatable())
2468 load_seg
= this->find_first_load_seg(target
);
2470 if (parameters
->options().oformat_enum()
2471 != General_options::OBJECT_FORMAT_ELF
)
2474 if (load_seg_unusable_for_headers(target
))
2480 gold_assert(phdr_seg
== NULL
2482 || this->script_options_
->saw_sections_clause());
2484 // If the address of the load segment we found has been set by
2485 // --section-start rather than by a script, then adjust the VMA and
2486 // LMA downward if possible to include the file and section headers.
2487 uint64_t header_gap
= 0;
2488 if (load_seg
!= NULL
2489 && load_seg
->are_addresses_set()
2490 && !this->script_options_
->saw_sections_clause()
2491 && !parameters
->options().relocatable())
2493 file_header
->finalize_data_size();
2494 segment_headers
->finalize_data_size();
2495 size_t sizeof_headers
= (file_header
->data_size()
2496 + segment_headers
->data_size());
2497 const uint64_t abi_pagesize
= target
->abi_pagesize();
2498 uint64_t hdr_paddr
= load_seg
->paddr() - sizeof_headers
;
2499 hdr_paddr
&= ~(abi_pagesize
- 1);
2500 uint64_t subtract
= load_seg
->paddr() - hdr_paddr
;
2501 if (load_seg
->paddr() < subtract
|| load_seg
->vaddr() < subtract
)
2505 load_seg
->set_addresses(load_seg
->vaddr() - subtract
,
2506 load_seg
->paddr() - subtract
);
2507 header_gap
= subtract
- sizeof_headers
;
2511 // Lay out the segment headers.
2512 if (!parameters
->options().relocatable())
2514 gold_assert(segment_headers
!= NULL
);
2515 if (header_gap
!= 0 && load_seg
!= NULL
)
2517 Output_data_zero_fill
* z
= new Output_data_zero_fill(header_gap
, 1);
2518 load_seg
->add_initial_output_data(z
);
2520 if (load_seg
!= NULL
)
2521 load_seg
->add_initial_output_data(segment_headers
);
2522 if (phdr_seg
!= NULL
)
2523 phdr_seg
->add_initial_output_data(segment_headers
);
2526 // Lay out the file header.
2527 if (load_seg
!= NULL
)
2528 load_seg
->add_initial_output_data(file_header
);
2530 if (this->script_options_
->saw_phdrs_clause()
2531 && !parameters
->options().relocatable())
2533 // Support use of FILEHDRS and PHDRS attachments in a PHDRS
2534 // clause in a linker script.
2535 Script_sections
* ss
= this->script_options_
->script_sections();
2536 ss
->put_headers_in_phdrs(file_header
, segment_headers
);
2539 // We set the output section indexes in set_segment_offsets and
2540 // set_section_indexes.
2543 // Set the file offsets of all the segments, and all the sections
2546 if (!parameters
->options().relocatable())
2547 off
= this->set_segment_offsets(target
, load_seg
, pshndx
);
2549 off
= this->set_relocatable_section_offsets(file_header
, pshndx
);
2551 // Verify that the dummy relaxation does not change anything.
2552 if (is_debugging_enabled(DEBUG_RELAXATION
))
2555 this->relaxation_debug_check_
->read_sections(this->section_list_
);
2557 this->relaxation_debug_check_
->verify_sections(this->section_list_
);
2560 *pload_seg
= load_seg
;
2564 // Search the list of patterns and find the postion of the given section
2565 // name in the output section. If the section name matches a glob
2566 // pattern and a non-glob name, then the non-glob position takes
2567 // precedence. Return 0 if no match is found.
2570 Layout::find_section_order_index(const std::string
& section_name
)
2572 Unordered_map
<std::string
, unsigned int>::iterator map_it
;
2573 map_it
= this->input_section_position_
.find(section_name
);
2574 if (map_it
!= this->input_section_position_
.end())
2575 return map_it
->second
;
2577 // Absolute match failed. Linear search the glob patterns.
2578 std::vector
<std::string
>::iterator it
;
2579 for (it
= this->input_section_glob_
.begin();
2580 it
!= this->input_section_glob_
.end();
2583 if (fnmatch((*it
).c_str(), section_name
.c_str(), FNM_NOESCAPE
) == 0)
2585 map_it
= this->input_section_position_
.find(*it
);
2586 gold_assert(map_it
!= this->input_section_position_
.end());
2587 return map_it
->second
;
2593 // Read the sequence of input sections from the file specified with
2594 // option --section-ordering-file.
2597 Layout::read_layout_from_file()
2599 const char* filename
= parameters
->options().section_ordering_file();
2605 gold_fatal(_("unable to open --section-ordering-file file %s: %s"),
2606 filename
, strerror(errno
));
2608 std::getline(in
, line
); // this chops off the trailing \n, if any
2609 unsigned int position
= 1;
2610 this->set_section_ordering_specified();
2614 if (!line
.empty() && line
[line
.length() - 1] == '\r') // Windows
2615 line
.resize(line
.length() - 1);
2616 // Ignore comments, beginning with '#'
2619 std::getline(in
, line
);
2622 this->input_section_position_
[line
] = position
;
2623 // Store all glob patterns in a vector.
2624 if (is_wildcard_string(line
.c_str()))
2625 this->input_section_glob_
.push_back(line
);
2627 std::getline(in
, line
);
2631 // Finalize the layout. When this is called, we have created all the
2632 // output sections and all the output segments which are based on
2633 // input sections. We have several things to do, and we have to do
2634 // them in the right order, so that we get the right results correctly
2637 // 1) Finalize the list of output segments and create the segment
2640 // 2) Finalize the dynamic symbol table and associated sections.
2642 // 3) Determine the final file offset of all the output segments.
2644 // 4) Determine the final file offset of all the SHF_ALLOC output
2647 // 5) Create the symbol table sections and the section name table
2650 // 6) Finalize the symbol table: set symbol values to their final
2651 // value and make a final determination of which symbols are going
2652 // into the output symbol table.
2654 // 7) Create the section table header.
2656 // 8) Determine the final file offset of all the output sections which
2657 // are not SHF_ALLOC, including the section table header.
2659 // 9) Finalize the ELF file header.
2661 // This function returns the size of the output file.
2664 Layout::finalize(const Input_objects
* input_objects
, Symbol_table
* symtab
,
2665 Target
* target
, const Task
* task
)
2667 target
->finalize_sections(this, input_objects
, symtab
);
2669 this->count_local_symbols(task
, input_objects
);
2671 this->link_stabs_sections();
2673 Output_segment
* phdr_seg
= NULL
;
2674 if (!parameters
->options().relocatable() && !parameters
->doing_static_link())
2676 // There was a dynamic object in the link. We need to create
2677 // some information for the dynamic linker.
2679 // Create the PT_PHDR segment which will hold the program
2681 if (!this->script_options_
->saw_phdrs_clause())
2682 phdr_seg
= this->make_output_segment(elfcpp::PT_PHDR
, elfcpp::PF_R
);
2684 // Create the dynamic symbol table, including the hash table.
2685 Output_section
* dynstr
;
2686 std::vector
<Symbol
*> dynamic_symbols
;
2687 unsigned int local_dynamic_count
;
2688 Versions
versions(*this->script_options()->version_script_info(),
2690 this->create_dynamic_symtab(input_objects
, symtab
, &dynstr
,
2691 &local_dynamic_count
, &dynamic_symbols
,
2694 // Create the .interp section to hold the name of the
2695 // interpreter, and put it in a PT_INTERP segment. Don't do it
2696 // if we saw a .interp section in an input file.
2697 if ((!parameters
->options().shared()
2698 || parameters
->options().dynamic_linker() != NULL
)
2699 && this->interp_segment_
== NULL
)
2700 this->create_interp(target
);
2702 // Finish the .dynamic section to hold the dynamic data, and put
2703 // it in a PT_DYNAMIC segment.
2704 this->finish_dynamic_section(input_objects
, symtab
);
2706 // We should have added everything we need to the dynamic string
2708 this->dynpool_
.set_string_offsets();
2710 // Create the version sections. We can't do this until the
2711 // dynamic string table is complete.
2712 this->create_version_sections(&versions
, symtab
, local_dynamic_count
,
2713 dynamic_symbols
, dynstr
);
2715 // Set the size of the _DYNAMIC symbol. We can't do this until
2716 // after we call create_version_sections.
2717 this->set_dynamic_symbol_size(symtab
);
2720 // Create segment headers.
2721 Output_segment_headers
* segment_headers
=
2722 (parameters
->options().relocatable()
2724 : new Output_segment_headers(this->segment_list_
));
2726 // Lay out the file header.
2727 Output_file_header
* file_header
= new Output_file_header(target
, symtab
,
2730 this->special_output_list_
.push_back(file_header
);
2731 if (segment_headers
!= NULL
)
2732 this->special_output_list_
.push_back(segment_headers
);
2734 // Find approriate places for orphan output sections if we are using
2736 if (this->script_options_
->saw_sections_clause())
2737 this->place_orphan_sections_in_script();
2739 Output_segment
* load_seg
;
2744 // Take a snapshot of the section layout as needed.
2745 if (target
->may_relax())
2746 this->prepare_for_relaxation();
2748 // Run the relaxation loop to lay out sections.
2751 off
= this->relaxation_loop_body(pass
, target
, symtab
, &load_seg
,
2752 phdr_seg
, segment_headers
, file_header
,
2756 while (target
->may_relax()
2757 && target
->relax(pass
, input_objects
, symtab
, this, task
));
2759 // If there is a load segment that contains the file and program headers,
2760 // provide a symbol __ehdr_start pointing there.
2761 // A program can use this to examine itself robustly.
2762 Symbol
*ehdr_start
= symtab
->lookup("__ehdr_start");
2763 if (ehdr_start
!= NULL
&& ehdr_start
->is_predefined())
2765 if (load_seg
!= NULL
)
2766 ehdr_start
->set_output_segment(load_seg
, Symbol::SEGMENT_START
);
2768 ehdr_start
->set_undefined();
2771 // Set the file offsets of all the non-data sections we've seen so
2772 // far which don't have to wait for the input sections. We need
2773 // this in order to finalize local symbols in non-allocated
2775 off
= this->set_section_offsets(off
, BEFORE_INPUT_SECTIONS_PASS
);
2777 // Set the section indexes of all unallocated sections seen so far,
2778 // in case any of them are somehow referenced by a symbol.
2779 shndx
= this->set_section_indexes(shndx
);
2781 // Create the symbol table sections.
2782 this->create_symtab_sections(input_objects
, symtab
, shndx
, &off
);
2783 if (!parameters
->doing_static_link())
2784 this->assign_local_dynsym_offsets(input_objects
);
2786 // Process any symbol assignments from a linker script. This must
2787 // be called after the symbol table has been finalized.
2788 this->script_options_
->finalize_symbols(symtab
, this);
2790 // Create the incremental inputs sections.
2791 if (this->incremental_inputs_
)
2793 this->incremental_inputs_
->finalize();
2794 this->create_incremental_info_sections(symtab
);
2797 // Create the .shstrtab section.
2798 Output_section
* shstrtab_section
= this->create_shstrtab();
2800 // Set the file offsets of the rest of the non-data sections which
2801 // don't have to wait for the input sections.
2802 off
= this->set_section_offsets(off
, BEFORE_INPUT_SECTIONS_PASS
);
2804 // Now that all sections have been created, set the section indexes
2805 // for any sections which haven't been done yet.
2806 shndx
= this->set_section_indexes(shndx
);
2808 // Create the section table header.
2809 this->create_shdrs(shstrtab_section
, &off
);
2811 // If there are no sections which require postprocessing, we can
2812 // handle the section names now, and avoid a resize later.
2813 if (!this->any_postprocessing_sections_
)
2815 off
= this->set_section_offsets(off
,
2816 POSTPROCESSING_SECTIONS_PASS
);
2818 this->set_section_offsets(off
,
2819 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
);
2822 file_header
->set_section_info(this->section_headers_
, shstrtab_section
);
2824 // Now we know exactly where everything goes in the output file
2825 // (except for non-allocated sections which require postprocessing).
2826 Output_data::layout_complete();
2828 this->output_file_size_
= off
;
2833 // Create a note header following the format defined in the ELF ABI.
2834 // NAME is the name, NOTE_TYPE is the type, SECTION_NAME is the name
2835 // of the section to create, DESCSZ is the size of the descriptor.
2836 // ALLOCATE is true if the section should be allocated in memory.
2837 // This returns the new note section. It sets *TRAILING_PADDING to
2838 // the number of trailing zero bytes required.
2841 Layout::create_note(const char* name
, int note_type
,
2842 const char* section_name
, size_t descsz
,
2843 bool allocate
, size_t* trailing_padding
)
2845 // Authorities all agree that the values in a .note field should
2846 // be aligned on 4-byte boundaries for 32-bit binaries. However,
2847 // they differ on what the alignment is for 64-bit binaries.
2848 // The GABI says unambiguously they take 8-byte alignment:
2849 // http://sco.com/developers/gabi/latest/ch5.pheader.html#note_section
2850 // Other documentation says alignment should always be 4 bytes:
2851 // http://www.netbsd.org/docs/kernel/elf-notes.html#note-format
2852 // GNU ld and GNU readelf both support the latter (at least as of
2853 // version 2.16.91), and glibc always generates the latter for
2854 // .note.ABI-tag (as of version 1.6), so that's the one we go with
2856 #ifdef GABI_FORMAT_FOR_DOTNOTE_SECTION // This is not defined by default.
2857 const int size
= parameters
->target().get_size();
2859 const int size
= 32;
2862 // The contents of the .note section.
2863 size_t namesz
= strlen(name
) + 1;
2864 size_t aligned_namesz
= align_address(namesz
, size
/ 8);
2865 size_t aligned_descsz
= align_address(descsz
, size
/ 8);
2867 size_t notehdrsz
= 3 * (size
/ 8) + aligned_namesz
;
2869 unsigned char* buffer
= new unsigned char[notehdrsz
];
2870 memset(buffer
, 0, notehdrsz
);
2872 bool is_big_endian
= parameters
->target().is_big_endian();
2878 elfcpp::Swap
<32, false>::writeval(buffer
, namesz
);
2879 elfcpp::Swap
<32, false>::writeval(buffer
+ 4, descsz
);
2880 elfcpp::Swap
<32, false>::writeval(buffer
+ 8, note_type
);
2884 elfcpp::Swap
<32, true>::writeval(buffer
, namesz
);
2885 elfcpp::Swap
<32, true>::writeval(buffer
+ 4, descsz
);
2886 elfcpp::Swap
<32, true>::writeval(buffer
+ 8, note_type
);
2889 else if (size
== 64)
2893 elfcpp::Swap
<64, false>::writeval(buffer
, namesz
);
2894 elfcpp::Swap
<64, false>::writeval(buffer
+ 8, descsz
);
2895 elfcpp::Swap
<64, false>::writeval(buffer
+ 16, note_type
);
2899 elfcpp::Swap
<64, true>::writeval(buffer
, namesz
);
2900 elfcpp::Swap
<64, true>::writeval(buffer
+ 8, descsz
);
2901 elfcpp::Swap
<64, true>::writeval(buffer
+ 16, note_type
);
2907 memcpy(buffer
+ 3 * (size
/ 8), name
, namesz
);
2909 elfcpp::Elf_Xword flags
= 0;
2910 Output_section_order order
= ORDER_INVALID
;
2913 flags
= elfcpp::SHF_ALLOC
;
2914 order
= ORDER_RO_NOTE
;
2916 Output_section
* os
= this->choose_output_section(NULL
, section_name
,
2918 flags
, false, order
, false);
2922 Output_section_data
* posd
= new Output_data_const_buffer(buffer
, notehdrsz
,
2925 os
->add_output_section_data(posd
);
2927 *trailing_padding
= aligned_descsz
- descsz
;
2932 // For an executable or shared library, create a note to record the
2933 // version of gold used to create the binary.
2936 Layout::create_gold_note()
2938 if (parameters
->options().relocatable()
2939 || parameters
->incremental_update())
2942 std::string desc
= std::string("gold ") + gold::get_version_string();
2944 size_t trailing_padding
;
2945 Output_section
* os
= this->create_note("GNU", elfcpp::NT_GNU_GOLD_VERSION
,
2946 ".note.gnu.gold-version", desc
.size(),
2947 false, &trailing_padding
);
2951 Output_section_data
* posd
= new Output_data_const(desc
, 4);
2952 os
->add_output_section_data(posd
);
2954 if (trailing_padding
> 0)
2956 posd
= new Output_data_zero_fill(trailing_padding
, 0);
2957 os
->add_output_section_data(posd
);
2961 // Record whether the stack should be executable. This can be set
2962 // from the command line using the -z execstack or -z noexecstack
2963 // options. Otherwise, if any input file has a .note.GNU-stack
2964 // section with the SHF_EXECINSTR flag set, the stack should be
2965 // executable. Otherwise, if at least one input file a
2966 // .note.GNU-stack section, and some input file has no .note.GNU-stack
2967 // section, we use the target default for whether the stack should be
2968 // executable. Otherwise, we don't generate a stack note. When
2969 // generating a object file, we create a .note.GNU-stack section with
2970 // the appropriate marking. When generating an executable or shared
2971 // library, we create a PT_GNU_STACK segment.
2974 Layout::create_executable_stack_info()
2976 bool is_stack_executable
;
2977 if (parameters
->options().is_execstack_set())
2978 is_stack_executable
= parameters
->options().is_stack_executable();
2979 else if (!this->input_with_gnu_stack_note_
)
2983 if (this->input_requires_executable_stack_
)
2984 is_stack_executable
= true;
2985 else if (this->input_without_gnu_stack_note_
)
2986 is_stack_executable
=
2987 parameters
->target().is_default_stack_executable();
2989 is_stack_executable
= false;
2992 if (parameters
->options().relocatable())
2994 const char* name
= this->namepool_
.add(".note.GNU-stack", false, NULL
);
2995 elfcpp::Elf_Xword flags
= 0;
2996 if (is_stack_executable
)
2997 flags
|= elfcpp::SHF_EXECINSTR
;
2998 this->make_output_section(name
, elfcpp::SHT_PROGBITS
, flags
,
2999 ORDER_INVALID
, false);
3003 if (this->script_options_
->saw_phdrs_clause())
3005 int flags
= elfcpp::PF_R
| elfcpp::PF_W
;
3006 if (is_stack_executable
)
3007 flags
|= elfcpp::PF_X
;
3008 this->make_output_segment(elfcpp::PT_GNU_STACK
, flags
);
3012 // If --build-id was used, set up the build ID note.
3015 Layout::create_build_id()
3017 if (!parameters
->options().user_set_build_id())
3020 const char* style
= parameters
->options().build_id();
3021 if (strcmp(style
, "none") == 0)
3024 // Set DESCSZ to the size of the note descriptor. When possible,
3025 // set DESC to the note descriptor contents.
3028 if (strcmp(style
, "md5") == 0)
3030 else if ((strcmp(style
, "sha1") == 0) || (strcmp(style
, "tree") == 0))
3032 else if (strcmp(style
, "uuid") == 0)
3034 const size_t uuidsz
= 128 / 8;
3036 char buffer
[uuidsz
];
3037 memset(buffer
, 0, uuidsz
);
3039 int descriptor
= open_descriptor(-1, "/dev/urandom", O_RDONLY
);
3041 gold_error(_("--build-id=uuid failed: could not open /dev/urandom: %s"),
3045 ssize_t got
= ::read(descriptor
, buffer
, uuidsz
);
3046 release_descriptor(descriptor
, true);
3048 gold_error(_("/dev/urandom: read failed: %s"), strerror(errno
));
3049 else if (static_cast<size_t>(got
) != uuidsz
)
3050 gold_error(_("/dev/urandom: expected %zu bytes, got %zd bytes"),
3054 desc
.assign(buffer
, uuidsz
);
3057 else if (strncmp(style
, "0x", 2) == 0)
3060 const char* p
= style
+ 2;
3063 if (hex_p(p
[0]) && hex_p(p
[1]))
3065 char c
= (hex_value(p
[0]) << 4) | hex_value(p
[1]);
3069 else if (*p
== '-' || *p
== ':')
3072 gold_fatal(_("--build-id argument '%s' not a valid hex number"),
3075 descsz
= desc
.size();
3078 gold_fatal(_("unrecognized --build-id argument '%s'"), style
);
3081 size_t trailing_padding
;
3082 Output_section
* os
= this->create_note("GNU", elfcpp::NT_GNU_BUILD_ID
,
3083 ".note.gnu.build-id", descsz
, true,
3090 // We know the value already, so we fill it in now.
3091 gold_assert(desc
.size() == descsz
);
3093 Output_section_data
* posd
= new Output_data_const(desc
, 4);
3094 os
->add_output_section_data(posd
);
3096 if (trailing_padding
!= 0)
3098 posd
= new Output_data_zero_fill(trailing_padding
, 0);
3099 os
->add_output_section_data(posd
);
3104 // We need to compute a checksum after we have completed the
3106 gold_assert(trailing_padding
== 0);
3107 this->build_id_note_
= new Output_data_zero_fill(descsz
, 4);
3108 os
->add_output_section_data(this->build_id_note_
);
3112 // If we have both .stabXX and .stabXXstr sections, then the sh_link
3113 // field of the former should point to the latter. I'm not sure who
3114 // started this, but the GNU linker does it, and some tools depend
3118 Layout::link_stabs_sections()
3120 if (!this->have_stabstr_section_
)
3123 for (Section_list::iterator p
= this->section_list_
.begin();
3124 p
!= this->section_list_
.end();
3127 if ((*p
)->type() != elfcpp::SHT_STRTAB
)
3130 const char* name
= (*p
)->name();
3131 if (strncmp(name
, ".stab", 5) != 0)
3134 size_t len
= strlen(name
);
3135 if (strcmp(name
+ len
- 3, "str") != 0)
3138 std::string
stab_name(name
, len
- 3);
3139 Output_section
* stab_sec
;
3140 stab_sec
= this->find_output_section(stab_name
.c_str());
3141 if (stab_sec
!= NULL
)
3142 stab_sec
->set_link_section(*p
);
3146 // Create .gnu_incremental_inputs and related sections needed
3147 // for the next run of incremental linking to check what has changed.
3150 Layout::create_incremental_info_sections(Symbol_table
* symtab
)
3152 Incremental_inputs
* incr
= this->incremental_inputs_
;
3154 gold_assert(incr
!= NULL
);
3156 // Create the .gnu_incremental_inputs, _symtab, and _relocs input sections.
3157 incr
->create_data_sections(symtab
);
3159 // Add the .gnu_incremental_inputs section.
3160 const char* incremental_inputs_name
=
3161 this->namepool_
.add(".gnu_incremental_inputs", false, NULL
);
3162 Output_section
* incremental_inputs_os
=
3163 this->make_output_section(incremental_inputs_name
,
3164 elfcpp::SHT_GNU_INCREMENTAL_INPUTS
, 0,
3165 ORDER_INVALID
, false);
3166 incremental_inputs_os
->add_output_section_data(incr
->inputs_section());
3168 // Add the .gnu_incremental_symtab section.
3169 const char* incremental_symtab_name
=
3170 this->namepool_
.add(".gnu_incremental_symtab", false, NULL
);
3171 Output_section
* incremental_symtab_os
=
3172 this->make_output_section(incremental_symtab_name
,
3173 elfcpp::SHT_GNU_INCREMENTAL_SYMTAB
, 0,
3174 ORDER_INVALID
, false);
3175 incremental_symtab_os
->add_output_section_data(incr
->symtab_section());
3176 incremental_symtab_os
->set_entsize(4);
3178 // Add the .gnu_incremental_relocs section.
3179 const char* incremental_relocs_name
=
3180 this->namepool_
.add(".gnu_incremental_relocs", false, NULL
);
3181 Output_section
* incremental_relocs_os
=
3182 this->make_output_section(incremental_relocs_name
,
3183 elfcpp::SHT_GNU_INCREMENTAL_RELOCS
, 0,
3184 ORDER_INVALID
, false);
3185 incremental_relocs_os
->add_output_section_data(incr
->relocs_section());
3186 incremental_relocs_os
->set_entsize(incr
->relocs_entsize());
3188 // Add the .gnu_incremental_got_plt section.
3189 const char* incremental_got_plt_name
=
3190 this->namepool_
.add(".gnu_incremental_got_plt", false, NULL
);
3191 Output_section
* incremental_got_plt_os
=
3192 this->make_output_section(incremental_got_plt_name
,
3193 elfcpp::SHT_GNU_INCREMENTAL_GOT_PLT
, 0,
3194 ORDER_INVALID
, false);
3195 incremental_got_plt_os
->add_output_section_data(incr
->got_plt_section());
3197 // Add the .gnu_incremental_strtab section.
3198 const char* incremental_strtab_name
=
3199 this->namepool_
.add(".gnu_incremental_strtab", false, NULL
);
3200 Output_section
* incremental_strtab_os
= this->make_output_section(incremental_strtab_name
,
3201 elfcpp::SHT_STRTAB
, 0,
3202 ORDER_INVALID
, false);
3203 Output_data_strtab
* strtab_data
=
3204 new Output_data_strtab(incr
->get_stringpool());
3205 incremental_strtab_os
->add_output_section_data(strtab_data
);
3207 incremental_inputs_os
->set_after_input_sections();
3208 incremental_symtab_os
->set_after_input_sections();
3209 incremental_relocs_os
->set_after_input_sections();
3210 incremental_got_plt_os
->set_after_input_sections();
3212 incremental_inputs_os
->set_link_section(incremental_strtab_os
);
3213 incremental_symtab_os
->set_link_section(incremental_inputs_os
);
3214 incremental_relocs_os
->set_link_section(incremental_inputs_os
);
3215 incremental_got_plt_os
->set_link_section(incremental_inputs_os
);
3218 // Return whether SEG1 should be before SEG2 in the output file. This
3219 // is based entirely on the segment type and flags. When this is
3220 // called the segment addresses have normally not yet been set.
3223 Layout::segment_precedes(const Output_segment
* seg1
,
3224 const Output_segment
* seg2
)
3226 elfcpp::Elf_Word type1
= seg1
->type();
3227 elfcpp::Elf_Word type2
= seg2
->type();
3229 // The single PT_PHDR segment is required to precede any loadable
3230 // segment. We simply make it always first.
3231 if (type1
== elfcpp::PT_PHDR
)
3233 gold_assert(type2
!= elfcpp::PT_PHDR
);
3236 if (type2
== elfcpp::PT_PHDR
)
3239 // The single PT_INTERP segment is required to precede any loadable
3240 // segment. We simply make it always second.
3241 if (type1
== elfcpp::PT_INTERP
)
3243 gold_assert(type2
!= elfcpp::PT_INTERP
);
3246 if (type2
== elfcpp::PT_INTERP
)
3249 // We then put PT_LOAD segments before any other segments.
3250 if (type1
== elfcpp::PT_LOAD
&& type2
!= elfcpp::PT_LOAD
)
3252 if (type2
== elfcpp::PT_LOAD
&& type1
!= elfcpp::PT_LOAD
)
3255 // We put the PT_TLS segment last except for the PT_GNU_RELRO
3256 // segment, because that is where the dynamic linker expects to find
3257 // it (this is just for efficiency; other positions would also work
3259 if (type1
== elfcpp::PT_TLS
3260 && type2
!= elfcpp::PT_TLS
3261 && type2
!= elfcpp::PT_GNU_RELRO
)
3263 if (type2
== elfcpp::PT_TLS
3264 && type1
!= elfcpp::PT_TLS
3265 && type1
!= elfcpp::PT_GNU_RELRO
)
3268 // We put the PT_GNU_RELRO segment last, because that is where the
3269 // dynamic linker expects to find it (as with PT_TLS, this is just
3271 if (type1
== elfcpp::PT_GNU_RELRO
&& type2
!= elfcpp::PT_GNU_RELRO
)
3273 if (type2
== elfcpp::PT_GNU_RELRO
&& type1
!= elfcpp::PT_GNU_RELRO
)
3276 const elfcpp::Elf_Word flags1
= seg1
->flags();
3277 const elfcpp::Elf_Word flags2
= seg2
->flags();
3279 // The order of non-PT_LOAD segments is unimportant. We simply sort
3280 // by the numeric segment type and flags values. There should not
3281 // be more than one segment with the same type and flags, except
3282 // when a linker script specifies such.
3283 if (type1
!= elfcpp::PT_LOAD
)
3286 return type1
< type2
;
3287 gold_assert(flags1
!= flags2
3288 || this->script_options_
->saw_phdrs_clause());
3289 return flags1
< flags2
;
3292 // If the addresses are set already, sort by load address.
3293 if (seg1
->are_addresses_set())
3295 if (!seg2
->are_addresses_set())
3298 unsigned int section_count1
= seg1
->output_section_count();
3299 unsigned int section_count2
= seg2
->output_section_count();
3300 if (section_count1
== 0 && section_count2
> 0)
3302 if (section_count1
> 0 && section_count2
== 0)
3305 uint64_t paddr1
= (seg1
->are_addresses_set()
3307 : seg1
->first_section_load_address());
3308 uint64_t paddr2
= (seg2
->are_addresses_set()
3310 : seg2
->first_section_load_address());
3312 if (paddr1
!= paddr2
)
3313 return paddr1
< paddr2
;
3315 else if (seg2
->are_addresses_set())
3318 // A segment which holds large data comes after a segment which does
3319 // not hold large data.
3320 if (seg1
->is_large_data_segment())
3322 if (!seg2
->is_large_data_segment())
3325 else if (seg2
->is_large_data_segment())
3328 // Otherwise, we sort PT_LOAD segments based on the flags. Readonly
3329 // segments come before writable segments. Then writable segments
3330 // with data come before writable segments without data. Then
3331 // executable segments come before non-executable segments. Then
3332 // the unlikely case of a non-readable segment comes before the
3333 // normal case of a readable segment. If there are multiple
3334 // segments with the same type and flags, we require that the
3335 // address be set, and we sort by virtual address and then physical
3337 if ((flags1
& elfcpp::PF_W
) != (flags2
& elfcpp::PF_W
))
3338 return (flags1
& elfcpp::PF_W
) == 0;
3339 if ((flags1
& elfcpp::PF_W
) != 0
3340 && seg1
->has_any_data_sections() != seg2
->has_any_data_sections())
3341 return seg1
->has_any_data_sections();
3342 if ((flags1
& elfcpp::PF_X
) != (flags2
& elfcpp::PF_X
))
3343 return (flags1
& elfcpp::PF_X
) != 0;
3344 if ((flags1
& elfcpp::PF_R
) != (flags2
& elfcpp::PF_R
))
3345 return (flags1
& elfcpp::PF_R
) == 0;
3347 // We shouldn't get here--we shouldn't create segments which we
3348 // can't distinguish. Unless of course we are using a weird linker
3349 // script or overlapping --section-start options. We could also get
3350 // here if plugins want unique segments for subsets of sections.
3351 gold_assert(this->script_options_
->saw_phdrs_clause()
3352 || parameters
->options().any_section_start()
3353 || this->is_unique_segment_for_sections_specified());
3357 // Increase OFF so that it is congruent to ADDR modulo ABI_PAGESIZE.
3360 align_file_offset(off_t off
, uint64_t addr
, uint64_t abi_pagesize
)
3362 uint64_t unsigned_off
= off
;
3363 uint64_t aligned_off
= ((unsigned_off
& ~(abi_pagesize
- 1))
3364 | (addr
& (abi_pagesize
- 1)));
3365 if (aligned_off
< unsigned_off
)
3366 aligned_off
+= abi_pagesize
;
3370 // On targets where the text segment contains only executable code,
3371 // a non-executable segment is never the text segment.
3374 is_text_segment(const Target
* target
, const Output_segment
* seg
)
3376 elfcpp::Elf_Xword flags
= seg
->flags();
3377 if ((flags
& elfcpp::PF_W
) != 0)
3379 if ((flags
& elfcpp::PF_X
) == 0)
3380 return !target
->isolate_execinstr();
3384 // Set the file offsets of all the segments, and all the sections they
3385 // contain. They have all been created. LOAD_SEG must be be laid out
3386 // first. Return the offset of the data to follow.
3389 Layout::set_segment_offsets(const Target
* target
, Output_segment
* load_seg
,
3390 unsigned int* pshndx
)
3392 // Sort them into the final order. We use a stable sort so that we
3393 // don't randomize the order of indistinguishable segments created
3394 // by linker scripts.
3395 std::stable_sort(this->segment_list_
.begin(), this->segment_list_
.end(),
3396 Layout::Compare_segments(this));
3398 // Find the PT_LOAD segments, and set their addresses and offsets
3399 // and their section's addresses and offsets.
3400 uint64_t start_addr
;
3401 if (parameters
->options().user_set_Ttext())
3402 start_addr
= parameters
->options().Ttext();
3403 else if (parameters
->options().output_is_position_independent())
3406 start_addr
= target
->default_text_segment_address();
3408 uint64_t addr
= start_addr
;
3411 // If LOAD_SEG is NULL, then the file header and segment headers
3412 // will not be loadable. But they still need to be at offset 0 in
3413 // the file. Set their offsets now.
3414 if (load_seg
== NULL
)
3416 for (Data_list::iterator p
= this->special_output_list_
.begin();
3417 p
!= this->special_output_list_
.end();
3420 off
= align_address(off
, (*p
)->addralign());
3421 (*p
)->set_address_and_file_offset(0, off
);
3422 off
+= (*p
)->data_size();
3426 unsigned int increase_relro
= this->increase_relro_
;
3427 if (this->script_options_
->saw_sections_clause())
3430 const bool check_sections
= parameters
->options().check_sections();
3431 Output_segment
* last_load_segment
= NULL
;
3433 unsigned int shndx_begin
= *pshndx
;
3434 unsigned int shndx_load_seg
= *pshndx
;
3436 for (Segment_list::iterator p
= this->segment_list_
.begin();
3437 p
!= this->segment_list_
.end();
3440 if ((*p
)->type() == elfcpp::PT_LOAD
)
3442 if (target
->isolate_execinstr())
3444 // When we hit the segment that should contain the
3445 // file headers, reset the file offset so we place
3446 // it and subsequent segments appropriately.
3447 // We'll fix up the preceding segments below.
3455 shndx_load_seg
= *pshndx
;
3461 // Verify that the file headers fall into the first segment.
3462 if (load_seg
!= NULL
&& load_seg
!= *p
)
3467 bool are_addresses_set
= (*p
)->are_addresses_set();
3468 if (are_addresses_set
)
3470 // When it comes to setting file offsets, we care about
3471 // the physical address.
3472 addr
= (*p
)->paddr();
3474 else if (parameters
->options().user_set_Ttext()
3475 && (parameters
->options().omagic()
3476 || is_text_segment(target
, *p
)))
3478 are_addresses_set
= true;
3480 else if (parameters
->options().user_set_Trodata_segment()
3481 && ((*p
)->flags() & (elfcpp::PF_W
| elfcpp::PF_X
)) == 0)
3483 addr
= parameters
->options().Trodata_segment();
3484 are_addresses_set
= true;
3486 else if (parameters
->options().user_set_Tdata()
3487 && ((*p
)->flags() & elfcpp::PF_W
) != 0
3488 && (!parameters
->options().user_set_Tbss()
3489 || (*p
)->has_any_data_sections()))
3491 addr
= parameters
->options().Tdata();
3492 are_addresses_set
= true;
3494 else if (parameters
->options().user_set_Tbss()
3495 && ((*p
)->flags() & elfcpp::PF_W
) != 0
3496 && !(*p
)->has_any_data_sections())
3498 addr
= parameters
->options().Tbss();
3499 are_addresses_set
= true;
3502 uint64_t orig_addr
= addr
;
3503 uint64_t orig_off
= off
;
3505 uint64_t aligned_addr
= 0;
3506 uint64_t abi_pagesize
= target
->abi_pagesize();
3507 uint64_t common_pagesize
= target
->common_pagesize();
3509 if (!parameters
->options().nmagic()
3510 && !parameters
->options().omagic())
3511 (*p
)->set_minimum_p_align(abi_pagesize
);
3513 if (!are_addresses_set
)
3515 // Skip the address forward one page, maintaining the same
3516 // position within the page. This lets us store both segments
3517 // overlapping on a single page in the file, but the loader will
3518 // put them on different pages in memory. We will revisit this
3519 // decision once we know the size of the segment.
3521 addr
= align_address(addr
, (*p
)->maximum_alignment());
3522 aligned_addr
= addr
;
3526 // This is the segment that will contain the file
3527 // headers, so its offset will have to be exactly zero.
3528 gold_assert(orig_off
== 0);
3530 // If the target wants a fixed minimum distance from the
3531 // text segment to the read-only segment, move up now.
3533 start_addr
+ (parameters
->options().user_set_rosegment_gap()
3534 ? parameters
->options().rosegment_gap()
3535 : target
->rosegment_gap());
3536 if (addr
< min_addr
)
3539 // But this is not the first segment! To make its
3540 // address congruent with its offset, that address better
3541 // be aligned to the ABI-mandated page size.
3542 addr
= align_address(addr
, abi_pagesize
);
3543 aligned_addr
= addr
;
3547 if ((addr
& (abi_pagesize
- 1)) != 0)
3548 addr
= addr
+ abi_pagesize
;
3550 off
= orig_off
+ ((addr
- orig_addr
) & (abi_pagesize
- 1));
3554 if (!parameters
->options().nmagic()
3555 && !parameters
->options().omagic())
3557 // Here we are also taking care of the case when
3558 // the maximum segment alignment is larger than the page size.
3559 off
= align_file_offset(off
, addr
,
3560 std::max(abi_pagesize
,
3561 (*p
)->maximum_alignment()));
3565 // This is -N or -n with a section script which prevents
3566 // us from using a load segment. We need to ensure that
3567 // the file offset is aligned to the alignment of the
3568 // segment. This is because the linker script
3569 // implicitly assumed a zero offset. If we don't align
3570 // here, then the alignment of the sections in the
3571 // linker script may not match the alignment of the
3572 // sections in the set_section_addresses call below,
3573 // causing an error about dot moving backward.
3574 off
= align_address(off
, (*p
)->maximum_alignment());
3577 unsigned int shndx_hold
= *pshndx
;
3578 bool has_relro
= false;
3579 uint64_t new_addr
= (*p
)->set_section_addresses(target
, this,
3585 // Now that we know the size of this segment, we may be able
3586 // to save a page in memory, at the cost of wasting some
3587 // file space, by instead aligning to the start of a new
3588 // page. Here we use the real machine page size rather than
3589 // the ABI mandated page size. If the segment has been
3590 // aligned so that the relro data ends at a page boundary,
3591 // we do not try to realign it.
3593 if (!are_addresses_set
3595 && aligned_addr
!= addr
3596 && !parameters
->incremental())
3598 uint64_t first_off
= (common_pagesize
3600 & (common_pagesize
- 1)));
3601 uint64_t last_off
= new_addr
& (common_pagesize
- 1);
3604 && ((aligned_addr
& ~ (common_pagesize
- 1))
3605 != (new_addr
& ~ (common_pagesize
- 1)))
3606 && first_off
+ last_off
<= common_pagesize
)
3608 *pshndx
= shndx_hold
;
3609 addr
= align_address(aligned_addr
, common_pagesize
);
3610 addr
= align_address(addr
, (*p
)->maximum_alignment());
3611 if ((addr
& (abi_pagesize
- 1)) != 0)
3612 addr
= addr
+ abi_pagesize
;
3613 off
= orig_off
+ ((addr
- orig_addr
) & (abi_pagesize
- 1));
3614 off
= align_file_offset(off
, addr
, abi_pagesize
);
3616 increase_relro
= this->increase_relro_
;
3617 if (this->script_options_
->saw_sections_clause())
3621 new_addr
= (*p
)->set_section_addresses(target
, this,
3631 // Implement --check-sections. We know that the segments
3632 // are sorted by LMA.
3633 if (check_sections
&& last_load_segment
!= NULL
)
3635 gold_assert(last_load_segment
->paddr() <= (*p
)->paddr());
3636 if (last_load_segment
->paddr() + last_load_segment
->memsz()
3639 unsigned long long lb1
= last_load_segment
->paddr();
3640 unsigned long long le1
= lb1
+ last_load_segment
->memsz();
3641 unsigned long long lb2
= (*p
)->paddr();
3642 unsigned long long le2
= lb2
+ (*p
)->memsz();
3643 gold_error(_("load segment overlap [0x%llx -> 0x%llx] and "
3644 "[0x%llx -> 0x%llx]"),
3645 lb1
, le1
, lb2
, le2
);
3648 last_load_segment
= *p
;
3652 if (load_seg
!= NULL
&& target
->isolate_execinstr())
3654 // Process the early segments again, setting their file offsets
3655 // so they land after the segments starting at LOAD_SEG.
3656 off
= align_file_offset(off
, 0, target
->abi_pagesize());
3658 this->reset_relax_output();
3660 for (Segment_list::iterator p
= this->segment_list_
.begin();
3664 if ((*p
)->type() == elfcpp::PT_LOAD
)
3666 // We repeat the whole job of assigning addresses and
3667 // offsets, but we really only want to change the offsets and
3668 // must ensure that the addresses all come out the same as
3669 // they did the first time through.
3670 bool has_relro
= false;
3671 const uint64_t old_addr
= (*p
)->vaddr();
3672 const uint64_t old_end
= old_addr
+ (*p
)->memsz();
3673 uint64_t new_addr
= (*p
)->set_section_addresses(target
, this,
3679 gold_assert(new_addr
== old_end
);
3683 gold_assert(shndx_begin
== shndx_load_seg
);
3686 // Handle the non-PT_LOAD segments, setting their offsets from their
3687 // section's offsets.
3688 for (Segment_list::iterator p
= this->segment_list_
.begin();
3689 p
!= this->segment_list_
.end();
3692 if ((*p
)->type() != elfcpp::PT_LOAD
)
3693 (*p
)->set_offset((*p
)->type() == elfcpp::PT_GNU_RELRO
3698 // Set the TLS offsets for each section in the PT_TLS segment.
3699 if (this->tls_segment_
!= NULL
)
3700 this->tls_segment_
->set_tls_offsets();
3705 // Set the offsets of all the allocated sections when doing a
3706 // relocatable link. This does the same jobs as set_segment_offsets,
3707 // only for a relocatable link.
3710 Layout::set_relocatable_section_offsets(Output_data
* file_header
,
3711 unsigned int* pshndx
)
3715 file_header
->set_address_and_file_offset(0, 0);
3716 off
+= file_header
->data_size();
3718 for (Section_list::iterator p
= this->section_list_
.begin();
3719 p
!= this->section_list_
.end();
3722 // We skip unallocated sections here, except that group sections
3723 // have to come first.
3724 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) == 0
3725 && (*p
)->type() != elfcpp::SHT_GROUP
)
3728 off
= align_address(off
, (*p
)->addralign());
3730 // The linker script might have set the address.
3731 if (!(*p
)->is_address_valid())
3732 (*p
)->set_address(0);
3733 (*p
)->set_file_offset(off
);
3734 (*p
)->finalize_data_size();
3735 if ((*p
)->type() != elfcpp::SHT_NOBITS
)
3736 off
+= (*p
)->data_size();
3738 (*p
)->set_out_shndx(*pshndx
);
3745 // Set the file offset of all the sections not associated with a
3749 Layout::set_section_offsets(off_t off
, Layout::Section_offset_pass pass
)
3751 off_t startoff
= off
;
3754 for (Section_list::iterator p
= this->unattached_section_list_
.begin();
3755 p
!= this->unattached_section_list_
.end();
3758 // The symtab section is handled in create_symtab_sections.
3759 if (*p
== this->symtab_section_
)
3762 // If we've already set the data size, don't set it again.
3763 if ((*p
)->is_offset_valid() && (*p
)->is_data_size_valid())
3766 if (pass
== BEFORE_INPUT_SECTIONS_PASS
3767 && (*p
)->requires_postprocessing())
3769 (*p
)->create_postprocessing_buffer();
3770 this->any_postprocessing_sections_
= true;
3773 if (pass
== BEFORE_INPUT_SECTIONS_PASS
3774 && (*p
)->after_input_sections())
3776 else if (pass
== POSTPROCESSING_SECTIONS_PASS
3777 && (!(*p
)->after_input_sections()
3778 || (*p
)->type() == elfcpp::SHT_STRTAB
))
3780 else if (pass
== STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
3781 && (!(*p
)->after_input_sections()
3782 || (*p
)->type() != elfcpp::SHT_STRTAB
))
3785 if (!parameters
->incremental_update())
3787 off
= align_address(off
, (*p
)->addralign());
3788 (*p
)->set_file_offset(off
);
3789 (*p
)->finalize_data_size();
3793 // Incremental update: allocate file space from free list.
3794 (*p
)->pre_finalize_data_size();
3795 off_t current_size
= (*p
)->current_data_size();
3796 off
= this->allocate(current_size
, (*p
)->addralign(), startoff
);
3799 if (is_debugging_enabled(DEBUG_INCREMENTAL
))
3800 this->free_list_
.dump();
3801 gold_assert((*p
)->output_section() != NULL
);
3802 gold_fallback(_("out of patch space for section %s; "
3803 "relink with --incremental-full"),
3804 (*p
)->output_section()->name());
3806 (*p
)->set_file_offset(off
);
3807 (*p
)->finalize_data_size();
3808 if ((*p
)->data_size() > current_size
)
3810 gold_assert((*p
)->output_section() != NULL
);
3811 gold_fallback(_("%s: section changed size; "
3812 "relink with --incremental-full"),
3813 (*p
)->output_section()->name());
3815 gold_debug(DEBUG_INCREMENTAL
,
3816 "set_section_offsets: %08lx %08lx %s",
3817 static_cast<long>(off
),
3818 static_cast<long>((*p
)->data_size()),
3819 ((*p
)->output_section() != NULL
3820 ? (*p
)->output_section()->name() : "(special)"));
3823 off
+= (*p
)->data_size();
3827 // At this point the name must be set.
3828 if (pass
!= STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
)
3829 this->namepool_
.add((*p
)->name(), false, NULL
);
3834 // Set the section indexes of all the sections not associated with a
3838 Layout::set_section_indexes(unsigned int shndx
)
3840 for (Section_list::iterator p
= this->unattached_section_list_
.begin();
3841 p
!= this->unattached_section_list_
.end();
3844 if (!(*p
)->has_out_shndx())
3846 (*p
)->set_out_shndx(shndx
);
3853 // Set the section addresses according to the linker script. This is
3854 // only called when we see a SECTIONS clause. This returns the
3855 // program segment which should hold the file header and segment
3856 // headers, if any. It will return NULL if they should not be in a
3860 Layout::set_section_addresses_from_script(Symbol_table
* symtab
)
3862 Script_sections
* ss
= this->script_options_
->script_sections();
3863 gold_assert(ss
->saw_sections_clause());
3864 return this->script_options_
->set_section_addresses(symtab
, this);
3867 // Place the orphan sections in the linker script.
3870 Layout::place_orphan_sections_in_script()
3872 Script_sections
* ss
= this->script_options_
->script_sections();
3873 gold_assert(ss
->saw_sections_clause());
3875 // Place each orphaned output section in the script.
3876 for (Section_list::iterator p
= this->section_list_
.begin();
3877 p
!= this->section_list_
.end();
3880 if (!(*p
)->found_in_sections_clause())
3881 ss
->place_orphan(*p
);
3885 // Count the local symbols in the regular symbol table and the dynamic
3886 // symbol table, and build the respective string pools.
3889 Layout::count_local_symbols(const Task
* task
,
3890 const Input_objects
* input_objects
)
3892 // First, figure out an upper bound on the number of symbols we'll
3893 // be inserting into each pool. This helps us create the pools with
3894 // the right size, to avoid unnecessary hashtable resizing.
3895 unsigned int symbol_count
= 0;
3896 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
3897 p
!= input_objects
->relobj_end();
3899 symbol_count
+= (*p
)->local_symbol_count();
3901 // Go from "upper bound" to "estimate." We overcount for two
3902 // reasons: we double-count symbols that occur in more than one
3903 // object file, and we count symbols that are dropped from the
3904 // output. Add it all together and assume we overcount by 100%.
3907 // We assume all symbols will go into both the sympool and dynpool.
3908 this->sympool_
.reserve(symbol_count
);
3909 this->dynpool_
.reserve(symbol_count
);
3911 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
3912 p
!= input_objects
->relobj_end();
3915 Task_lock_obj
<Object
> tlo(task
, *p
);
3916 (*p
)->count_local_symbols(&this->sympool_
, &this->dynpool_
);
3920 // Create the symbol table sections. Here we also set the final
3921 // values of the symbols. At this point all the loadable sections are
3922 // fully laid out. SHNUM is the number of sections so far.
3925 Layout::create_symtab_sections(const Input_objects
* input_objects
,
3926 Symbol_table
* symtab
,
3932 if (parameters
->target().get_size() == 32)
3934 symsize
= elfcpp::Elf_sizes
<32>::sym_size
;
3937 else if (parameters
->target().get_size() == 64)
3939 symsize
= elfcpp::Elf_sizes
<64>::sym_size
;
3945 // Compute file offsets relative to the start of the symtab section.
3948 // Save space for the dummy symbol at the start of the section. We
3949 // never bother to write this out--it will just be left as zero.
3951 unsigned int local_symbol_index
= 1;
3953 // Add STT_SECTION symbols for each Output section which needs one.
3954 for (Section_list::iterator p
= this->section_list_
.begin();
3955 p
!= this->section_list_
.end();
3958 if (!(*p
)->needs_symtab_index())
3959 (*p
)->set_symtab_index(-1U);
3962 (*p
)->set_symtab_index(local_symbol_index
);
3963 ++local_symbol_index
;
3968 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
3969 p
!= input_objects
->relobj_end();
3972 unsigned int index
= (*p
)->finalize_local_symbols(local_symbol_index
,
3974 off
+= (index
- local_symbol_index
) * symsize
;
3975 local_symbol_index
= index
;
3978 unsigned int local_symcount
= local_symbol_index
;
3979 gold_assert(static_cast<off_t
>(local_symcount
* symsize
) == off
);
3982 size_t dyn_global_index
;
3984 if (this->dynsym_section_
== NULL
)
3987 dyn_global_index
= 0;
3992 dyn_global_index
= this->dynsym_section_
->info();
3993 off_t locsize
= dyn_global_index
* this->dynsym_section_
->entsize();
3994 dynoff
= this->dynsym_section_
->offset() + locsize
;
3995 dyncount
= (this->dynsym_section_
->data_size() - locsize
) / symsize
;
3996 gold_assert(static_cast<off_t
>(dyncount
* symsize
)
3997 == this->dynsym_section_
->data_size() - locsize
);
4000 off_t global_off
= off
;
4001 off
= symtab
->finalize(off
, dynoff
, dyn_global_index
, dyncount
,
4002 &this->sympool_
, &local_symcount
);
4004 if (!parameters
->options().strip_all())
4006 this->sympool_
.set_string_offsets();
4008 const char* symtab_name
= this->namepool_
.add(".symtab", false, NULL
);
4009 Output_section
* osymtab
= this->make_output_section(symtab_name
,
4013 this->symtab_section_
= osymtab
;
4015 Output_section_data
* pos
= new Output_data_fixed_space(off
, align
,
4017 osymtab
->add_output_section_data(pos
);
4019 // We generate a .symtab_shndx section if we have more than
4020 // SHN_LORESERVE sections. Technically it is possible that we
4021 // don't need one, because it is possible that there are no
4022 // symbols in any of sections with indexes larger than
4023 // SHN_LORESERVE. That is probably unusual, though, and it is
4024 // easier to always create one than to compute section indexes
4025 // twice (once here, once when writing out the symbols).
4026 if (shnum
>= elfcpp::SHN_LORESERVE
)
4028 const char* symtab_xindex_name
= this->namepool_
.add(".symtab_shndx",
4030 Output_section
* osymtab_xindex
=
4031 this->make_output_section(symtab_xindex_name
,
4032 elfcpp::SHT_SYMTAB_SHNDX
, 0,
4033 ORDER_INVALID
, false);
4035 size_t symcount
= off
/ symsize
;
4036 this->symtab_xindex_
= new Output_symtab_xindex(symcount
);
4038 osymtab_xindex
->add_output_section_data(this->symtab_xindex_
);
4040 osymtab_xindex
->set_link_section(osymtab
);
4041 osymtab_xindex
->set_addralign(4);
4042 osymtab_xindex
->set_entsize(4);
4044 osymtab_xindex
->set_after_input_sections();
4046 // This tells the driver code to wait until the symbol table
4047 // has written out before writing out the postprocessing
4048 // sections, including the .symtab_shndx section.
4049 this->any_postprocessing_sections_
= true;
4052 const char* strtab_name
= this->namepool_
.add(".strtab", false, NULL
);
4053 Output_section
* ostrtab
= this->make_output_section(strtab_name
,
4058 Output_section_data
* pstr
= new Output_data_strtab(&this->sympool_
);
4059 ostrtab
->add_output_section_data(pstr
);
4062 if (!parameters
->incremental_update())
4063 symtab_off
= align_address(*poff
, align
);
4066 symtab_off
= this->allocate(off
, align
, *poff
);
4068 gold_fallback(_("out of patch space for symbol table; "
4069 "relink with --incremental-full"));
4070 gold_debug(DEBUG_INCREMENTAL
,
4071 "create_symtab_sections: %08lx %08lx .symtab",
4072 static_cast<long>(symtab_off
),
4073 static_cast<long>(off
));
4076 symtab
->set_file_offset(symtab_off
+ global_off
);
4077 osymtab
->set_file_offset(symtab_off
);
4078 osymtab
->finalize_data_size();
4079 osymtab
->set_link_section(ostrtab
);
4080 osymtab
->set_info(local_symcount
);
4081 osymtab
->set_entsize(symsize
);
4083 if (symtab_off
+ off
> *poff
)
4084 *poff
= symtab_off
+ off
;
4088 // Create the .shstrtab section, which holds the names of the
4089 // sections. At the time this is called, we have created all the
4090 // output sections except .shstrtab itself.
4093 Layout::create_shstrtab()
4095 // FIXME: We don't need to create a .shstrtab section if we are
4096 // stripping everything.
4098 const char* name
= this->namepool_
.add(".shstrtab", false, NULL
);
4100 Output_section
* os
= this->make_output_section(name
, elfcpp::SHT_STRTAB
, 0,
4101 ORDER_INVALID
, false);
4103 if (strcmp(parameters
->options().compress_debug_sections(), "none") != 0)
4105 // We can't write out this section until we've set all the
4106 // section names, and we don't set the names of compressed
4107 // output sections until relocations are complete. FIXME: With
4108 // the current names we use, this is unnecessary.
4109 os
->set_after_input_sections();
4112 Output_section_data
* posd
= new Output_data_strtab(&this->namepool_
);
4113 os
->add_output_section_data(posd
);
4118 // Create the section headers. SIZE is 32 or 64. OFF is the file
4122 Layout::create_shdrs(const Output_section
* shstrtab_section
, off_t
* poff
)
4124 Output_section_headers
* oshdrs
;
4125 oshdrs
= new Output_section_headers(this,
4126 &this->segment_list_
,
4127 &this->section_list_
,
4128 &this->unattached_section_list_
,
4132 if (!parameters
->incremental_update())
4133 off
= align_address(*poff
, oshdrs
->addralign());
4136 oshdrs
->pre_finalize_data_size();
4137 off
= this->allocate(oshdrs
->data_size(), oshdrs
->addralign(), *poff
);
4139 gold_fallback(_("out of patch space for section header table; "
4140 "relink with --incremental-full"));
4141 gold_debug(DEBUG_INCREMENTAL
,
4142 "create_shdrs: %08lx %08lx (section header table)",
4143 static_cast<long>(off
),
4144 static_cast<long>(off
+ oshdrs
->data_size()));
4146 oshdrs
->set_address_and_file_offset(0, off
);
4147 off
+= oshdrs
->data_size();
4150 this->section_headers_
= oshdrs
;
4153 // Count the allocated sections.
4156 Layout::allocated_output_section_count() const
4158 size_t section_count
= 0;
4159 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
4160 p
!= this->segment_list_
.end();
4162 section_count
+= (*p
)->output_section_count();
4163 return section_count
;
4166 // Create the dynamic symbol table.
4169 Layout::create_dynamic_symtab(const Input_objects
* input_objects
,
4170 Symbol_table
* symtab
,
4171 Output_section
** pdynstr
,
4172 unsigned int* plocal_dynamic_count
,
4173 std::vector
<Symbol
*>* pdynamic_symbols
,
4174 Versions
* pversions
)
4176 // Count all the symbols in the dynamic symbol table, and set the
4177 // dynamic symbol indexes.
4179 // Skip symbol 0, which is always all zeroes.
4180 unsigned int index
= 1;
4182 // Add STT_SECTION symbols for each Output section which needs one.
4183 for (Section_list::iterator p
= this->section_list_
.begin();
4184 p
!= this->section_list_
.end();
4187 if (!(*p
)->needs_dynsym_index())
4188 (*p
)->set_dynsym_index(-1U);
4191 (*p
)->set_dynsym_index(index
);
4196 // Count the local symbols that need to go in the dynamic symbol table,
4197 // and set the dynamic symbol indexes.
4198 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
4199 p
!= input_objects
->relobj_end();
4202 unsigned int new_index
= (*p
)->set_local_dynsym_indexes(index
);
4206 unsigned int local_symcount
= index
;
4207 *plocal_dynamic_count
= local_symcount
;
4209 index
= symtab
->set_dynsym_indexes(index
, pdynamic_symbols
,
4210 &this->dynpool_
, pversions
);
4214 const int size
= parameters
->target().get_size();
4217 symsize
= elfcpp::Elf_sizes
<32>::sym_size
;
4220 else if (size
== 64)
4222 symsize
= elfcpp::Elf_sizes
<64>::sym_size
;
4228 // Create the dynamic symbol table section.
4230 Output_section
* dynsym
= this->choose_output_section(NULL
, ".dynsym",
4234 ORDER_DYNAMIC_LINKER
,
4237 // Check for NULL as a linker script may discard .dynsym.
4240 Output_section_data
* odata
= new Output_data_fixed_space(index
* symsize
,
4243 dynsym
->add_output_section_data(odata
);
4245 dynsym
->set_info(local_symcount
);
4246 dynsym
->set_entsize(symsize
);
4247 dynsym
->set_addralign(align
);
4249 this->dynsym_section_
= dynsym
;
4252 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
4255 odyn
->add_section_address(elfcpp::DT_SYMTAB
, dynsym
);
4256 odyn
->add_constant(elfcpp::DT_SYMENT
, symsize
);
4259 // If there are more than SHN_LORESERVE allocated sections, we
4260 // create a .dynsym_shndx section. It is possible that we don't
4261 // need one, because it is possible that there are no dynamic
4262 // symbols in any of the sections with indexes larger than
4263 // SHN_LORESERVE. This is probably unusual, though, and at this
4264 // time we don't know the actual section indexes so it is
4265 // inconvenient to check.
4266 if (this->allocated_output_section_count() >= elfcpp::SHN_LORESERVE
)
4268 Output_section
* dynsym_xindex
=
4269 this->choose_output_section(NULL
, ".dynsym_shndx",
4270 elfcpp::SHT_SYMTAB_SHNDX
,
4272 false, ORDER_DYNAMIC_LINKER
, false);
4274 if (dynsym_xindex
!= NULL
)
4276 this->dynsym_xindex_
= new Output_symtab_xindex(index
);
4278 dynsym_xindex
->add_output_section_data(this->dynsym_xindex_
);
4280 dynsym_xindex
->set_link_section(dynsym
);
4281 dynsym_xindex
->set_addralign(4);
4282 dynsym_xindex
->set_entsize(4);
4284 dynsym_xindex
->set_after_input_sections();
4286 // This tells the driver code to wait until the symbol table
4287 // has written out before writing out the postprocessing
4288 // sections, including the .dynsym_shndx section.
4289 this->any_postprocessing_sections_
= true;
4293 // Create the dynamic string table section.
4295 Output_section
* dynstr
= this->choose_output_section(NULL
, ".dynstr",
4299 ORDER_DYNAMIC_LINKER
,
4304 Output_section_data
* strdata
= new Output_data_strtab(&this->dynpool_
);
4305 dynstr
->add_output_section_data(strdata
);
4308 dynsym
->set_link_section(dynstr
);
4309 if (this->dynamic_section_
!= NULL
)
4310 this->dynamic_section_
->set_link_section(dynstr
);
4314 odyn
->add_section_address(elfcpp::DT_STRTAB
, dynstr
);
4315 odyn
->add_section_size(elfcpp::DT_STRSZ
, dynstr
);
4319 // Create the hash tables. The Gnu-style hash table must be
4320 // built first, because it changes the order of the symbols
4321 // in the dynamic symbol table.
4323 if (strcmp(parameters
->options().hash_style(), "gnu") == 0
4324 || strcmp(parameters
->options().hash_style(), "both") == 0)
4326 unsigned char* phash
;
4327 unsigned int hashlen
;
4328 Dynobj::create_gnu_hash_table(*pdynamic_symbols
, local_symcount
,
4331 Output_section
* hashsec
=
4332 this->choose_output_section(NULL
, ".gnu.hash", elfcpp::SHT_GNU_HASH
,
4333 elfcpp::SHF_ALLOC
, false,
4334 ORDER_DYNAMIC_LINKER
, false);
4336 Output_section_data
* hashdata
= new Output_data_const_buffer(phash
,
4340 if (hashsec
!= NULL
&& hashdata
!= NULL
)
4341 hashsec
->add_output_section_data(hashdata
);
4343 if (hashsec
!= NULL
)
4346 hashsec
->set_link_section(dynsym
);
4348 // For a 64-bit target, the entries in .gnu.hash do not have
4349 // a uniform size, so we only set the entry size for a
4351 if (parameters
->target().get_size() == 32)
4352 hashsec
->set_entsize(4);
4355 odyn
->add_section_address(elfcpp::DT_GNU_HASH
, hashsec
);
4359 if (strcmp(parameters
->options().hash_style(), "sysv") == 0
4360 || strcmp(parameters
->options().hash_style(), "both") == 0)
4362 unsigned char* phash
;
4363 unsigned int hashlen
;
4364 Dynobj::create_elf_hash_table(*pdynamic_symbols
, local_symcount
,
4367 Output_section
* hashsec
=
4368 this->choose_output_section(NULL
, ".hash", elfcpp::SHT_HASH
,
4369 elfcpp::SHF_ALLOC
, false,
4370 ORDER_DYNAMIC_LINKER
, false);
4372 Output_section_data
* hashdata
= new Output_data_const_buffer(phash
,
4376 if (hashsec
!= NULL
&& hashdata
!= NULL
)
4377 hashsec
->add_output_section_data(hashdata
);
4379 if (hashsec
!= NULL
)
4382 hashsec
->set_link_section(dynsym
);
4383 hashsec
->set_entsize(4);
4387 odyn
->add_section_address(elfcpp::DT_HASH
, hashsec
);
4391 // Assign offsets to each local portion of the dynamic symbol table.
4394 Layout::assign_local_dynsym_offsets(const Input_objects
* input_objects
)
4396 Output_section
* dynsym
= this->dynsym_section_
;
4400 off_t off
= dynsym
->offset();
4402 // Skip the dummy symbol at the start of the section.
4403 off
+= dynsym
->entsize();
4405 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
4406 p
!= input_objects
->relobj_end();
4409 unsigned int count
= (*p
)->set_local_dynsym_offset(off
);
4410 off
+= count
* dynsym
->entsize();
4414 // Create the version sections.
4417 Layout::create_version_sections(const Versions
* versions
,
4418 const Symbol_table
* symtab
,
4419 unsigned int local_symcount
,
4420 const std::vector
<Symbol
*>& dynamic_symbols
,
4421 const Output_section
* dynstr
)
4423 if (!versions
->any_defs() && !versions
->any_needs())
4426 switch (parameters
->size_and_endianness())
4428 #ifdef HAVE_TARGET_32_LITTLE
4429 case Parameters::TARGET_32_LITTLE
:
4430 this->sized_create_version_sections
<32, false>(versions
, symtab
,
4432 dynamic_symbols
, dynstr
);
4435 #ifdef HAVE_TARGET_32_BIG
4436 case Parameters::TARGET_32_BIG
:
4437 this->sized_create_version_sections
<32, true>(versions
, symtab
,
4439 dynamic_symbols
, dynstr
);
4442 #ifdef HAVE_TARGET_64_LITTLE
4443 case Parameters::TARGET_64_LITTLE
:
4444 this->sized_create_version_sections
<64, false>(versions
, symtab
,
4446 dynamic_symbols
, dynstr
);
4449 #ifdef HAVE_TARGET_64_BIG
4450 case Parameters::TARGET_64_BIG
:
4451 this->sized_create_version_sections
<64, true>(versions
, symtab
,
4453 dynamic_symbols
, dynstr
);
4461 // Create the version sections, sized version.
4463 template<int size
, bool big_endian
>
4465 Layout::sized_create_version_sections(
4466 const Versions
* versions
,
4467 const Symbol_table
* symtab
,
4468 unsigned int local_symcount
,
4469 const std::vector
<Symbol
*>& dynamic_symbols
,
4470 const Output_section
* dynstr
)
4472 Output_section
* vsec
= this->choose_output_section(NULL
, ".gnu.version",
4473 elfcpp::SHT_GNU_versym
,
4476 ORDER_DYNAMIC_LINKER
,
4479 // Check for NULL since a linker script may discard this section.
4482 unsigned char* vbuf
;
4484 versions
->symbol_section_contents
<size
, big_endian
>(symtab
,
4490 Output_section_data
* vdata
= new Output_data_const_buffer(vbuf
, vsize
, 2,
4493 vsec
->add_output_section_data(vdata
);
4494 vsec
->set_entsize(2);
4495 vsec
->set_link_section(this->dynsym_section_
);
4498 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
4499 if (odyn
!= NULL
&& vsec
!= NULL
)
4500 odyn
->add_section_address(elfcpp::DT_VERSYM
, vsec
);
4502 if (versions
->any_defs())
4504 Output_section
* vdsec
;
4505 vdsec
= this->choose_output_section(NULL
, ".gnu.version_d",
4506 elfcpp::SHT_GNU_verdef
,
4508 false, ORDER_DYNAMIC_LINKER
, false);
4512 unsigned char* vdbuf
;
4513 unsigned int vdsize
;
4514 unsigned int vdentries
;
4515 versions
->def_section_contents
<size
, big_endian
>(&this->dynpool_
,
4519 Output_section_data
* vddata
=
4520 new Output_data_const_buffer(vdbuf
, vdsize
, 4, "** version defs");
4522 vdsec
->add_output_section_data(vddata
);
4523 vdsec
->set_link_section(dynstr
);
4524 vdsec
->set_info(vdentries
);
4528 odyn
->add_section_address(elfcpp::DT_VERDEF
, vdsec
);
4529 odyn
->add_constant(elfcpp::DT_VERDEFNUM
, vdentries
);
4534 if (versions
->any_needs())
4536 Output_section
* vnsec
;
4537 vnsec
= this->choose_output_section(NULL
, ".gnu.version_r",
4538 elfcpp::SHT_GNU_verneed
,
4540 false, ORDER_DYNAMIC_LINKER
, false);
4544 unsigned char* vnbuf
;
4545 unsigned int vnsize
;
4546 unsigned int vnentries
;
4547 versions
->need_section_contents
<size
, big_endian
>(&this->dynpool_
,
4551 Output_section_data
* vndata
=
4552 new Output_data_const_buffer(vnbuf
, vnsize
, 4, "** version refs");
4554 vnsec
->add_output_section_data(vndata
);
4555 vnsec
->set_link_section(dynstr
);
4556 vnsec
->set_info(vnentries
);
4560 odyn
->add_section_address(elfcpp::DT_VERNEED
, vnsec
);
4561 odyn
->add_constant(elfcpp::DT_VERNEEDNUM
, vnentries
);
4567 // Create the .interp section and PT_INTERP segment.
4570 Layout::create_interp(const Target
* target
)
4572 gold_assert(this->interp_segment_
== NULL
);
4574 const char* interp
= parameters
->options().dynamic_linker();
4577 interp
= target
->dynamic_linker();
4578 gold_assert(interp
!= NULL
);
4581 size_t len
= strlen(interp
) + 1;
4583 Output_section_data
* odata
= new Output_data_const(interp
, len
, 1);
4585 Output_section
* osec
= this->choose_output_section(NULL
, ".interp",
4586 elfcpp::SHT_PROGBITS
,
4588 false, ORDER_INTERP
,
4591 osec
->add_output_section_data(odata
);
4594 // Add dynamic tags for the PLT and the dynamic relocs. This is
4595 // called by the target-specific code. This does nothing if not doing
4598 // USE_REL is true for REL relocs rather than RELA relocs.
4600 // If PLT_GOT is not NULL, then DT_PLTGOT points to it.
4602 // If PLT_REL is not NULL, it is used for DT_PLTRELSZ, and DT_JMPREL,
4603 // and we also set DT_PLTREL. We use PLT_REL's output section, since
4604 // some targets have multiple reloc sections in PLT_REL.
4606 // If DYN_REL is not NULL, it is used for DT_REL/DT_RELA,
4607 // DT_RELSZ/DT_RELASZ, DT_RELENT/DT_RELAENT. Again we use the output
4610 // If ADD_DEBUG is true, we add a DT_DEBUG entry when generating an
4614 Layout::add_target_dynamic_tags(bool use_rel
, const Output_data
* plt_got
,
4615 const Output_data
* plt_rel
,
4616 const Output_data_reloc_generic
* dyn_rel
,
4617 bool add_debug
, bool dynrel_includes_plt
)
4619 Output_data_dynamic
* odyn
= this->dynamic_data_
;
4623 if (plt_got
!= NULL
&& plt_got
->output_section() != NULL
)
4624 odyn
->add_section_address(elfcpp::DT_PLTGOT
, plt_got
);
4626 if (plt_rel
!= NULL
&& plt_rel
->output_section() != NULL
)
4628 odyn
->add_section_size(elfcpp::DT_PLTRELSZ
, plt_rel
->output_section());
4629 odyn
->add_section_address(elfcpp::DT_JMPREL
, plt_rel
->output_section());
4630 odyn
->add_constant(elfcpp::DT_PLTREL
,
4631 use_rel
? elfcpp::DT_REL
: elfcpp::DT_RELA
);
4634 if ((dyn_rel
!= NULL
&& dyn_rel
->output_section() != NULL
)
4635 || (dynrel_includes_plt
4637 && plt_rel
->output_section() != NULL
))
4639 bool have_dyn_rel
= dyn_rel
!= NULL
&& dyn_rel
->output_section() != NULL
;
4640 bool have_plt_rel
= plt_rel
!= NULL
&& plt_rel
->output_section() != NULL
;
4641 odyn
->add_section_address(use_rel
? elfcpp::DT_REL
: elfcpp::DT_RELA
,
4643 ? dyn_rel
->output_section()
4644 : plt_rel
->output_section()));
4645 elfcpp::DT size_tag
= use_rel
? elfcpp::DT_RELSZ
: elfcpp::DT_RELASZ
;
4646 if (have_dyn_rel
&& have_plt_rel
&& dynrel_includes_plt
)
4647 odyn
->add_section_size(size_tag
,
4648 dyn_rel
->output_section(),
4649 plt_rel
->output_section());
4650 else if (have_dyn_rel
)
4651 odyn
->add_section_size(size_tag
, dyn_rel
->output_section());
4653 odyn
->add_section_size(size_tag
, plt_rel
->output_section());
4654 const int size
= parameters
->target().get_size();
4659 rel_tag
= elfcpp::DT_RELENT
;
4661 rel_size
= Reloc_types
<elfcpp::SHT_REL
, 32, false>::reloc_size
;
4662 else if (size
== 64)
4663 rel_size
= Reloc_types
<elfcpp::SHT_REL
, 64, false>::reloc_size
;
4669 rel_tag
= elfcpp::DT_RELAENT
;
4671 rel_size
= Reloc_types
<elfcpp::SHT_RELA
, 32, false>::reloc_size
;
4672 else if (size
== 64)
4673 rel_size
= Reloc_types
<elfcpp::SHT_RELA
, 64, false>::reloc_size
;
4677 odyn
->add_constant(rel_tag
, rel_size
);
4679 if (parameters
->options().combreloc() && have_dyn_rel
)
4681 size_t c
= dyn_rel
->relative_reloc_count();
4683 odyn
->add_constant((use_rel
4684 ? elfcpp::DT_RELCOUNT
4685 : elfcpp::DT_RELACOUNT
),
4690 if (add_debug
&& !parameters
->options().shared())
4692 // The value of the DT_DEBUG tag is filled in by the dynamic
4693 // linker at run time, and used by the debugger.
4694 odyn
->add_constant(elfcpp::DT_DEBUG
, 0);
4698 // Finish the .dynamic section and PT_DYNAMIC segment.
4701 Layout::finish_dynamic_section(const Input_objects
* input_objects
,
4702 const Symbol_table
* symtab
)
4704 if (!this->script_options_
->saw_phdrs_clause()
4705 && this->dynamic_section_
!= NULL
)
4707 Output_segment
* oseg
= this->make_output_segment(elfcpp::PT_DYNAMIC
,
4710 oseg
->add_output_section_to_nonload(this->dynamic_section_
,
4711 elfcpp::PF_R
| elfcpp::PF_W
);
4714 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
4718 for (Input_objects::Dynobj_iterator p
= input_objects
->dynobj_begin();
4719 p
!= input_objects
->dynobj_end();
4722 if (!(*p
)->is_needed() && (*p
)->as_needed())
4724 // This dynamic object was linked with --as-needed, but it
4729 odyn
->add_string(elfcpp::DT_NEEDED
, (*p
)->soname());
4732 if (parameters
->options().shared())
4734 const char* soname
= parameters
->options().soname();
4736 odyn
->add_string(elfcpp::DT_SONAME
, soname
);
4739 Symbol
* sym
= symtab
->lookup(parameters
->options().init());
4740 if (sym
!= NULL
&& sym
->is_defined() && !sym
->is_from_dynobj())
4741 odyn
->add_symbol(elfcpp::DT_INIT
, sym
);
4743 sym
= symtab
->lookup(parameters
->options().fini());
4744 if (sym
!= NULL
&& sym
->is_defined() && !sym
->is_from_dynobj())
4745 odyn
->add_symbol(elfcpp::DT_FINI
, sym
);
4747 // Look for .init_array, .preinit_array and .fini_array by checking
4749 for(Layout::Section_list::const_iterator p
= this->section_list_
.begin();
4750 p
!= this->section_list_
.end();
4752 switch((*p
)->type())
4754 case elfcpp::SHT_FINI_ARRAY
:
4755 odyn
->add_section_address(elfcpp::DT_FINI_ARRAY
, *p
);
4756 odyn
->add_section_size(elfcpp::DT_FINI_ARRAYSZ
, *p
);
4758 case elfcpp::SHT_INIT_ARRAY
:
4759 odyn
->add_section_address(elfcpp::DT_INIT_ARRAY
, *p
);
4760 odyn
->add_section_size(elfcpp::DT_INIT_ARRAYSZ
, *p
);
4762 case elfcpp::SHT_PREINIT_ARRAY
:
4763 odyn
->add_section_address(elfcpp::DT_PREINIT_ARRAY
, *p
);
4764 odyn
->add_section_size(elfcpp::DT_PREINIT_ARRAYSZ
, *p
);
4770 // Add a DT_RPATH entry if needed.
4771 const General_options::Dir_list
& rpath(parameters
->options().rpath());
4774 std::string rpath_val
;
4775 for (General_options::Dir_list::const_iterator p
= rpath
.begin();
4779 if (rpath_val
.empty())
4780 rpath_val
= p
->name();
4783 // Eliminate duplicates.
4784 General_options::Dir_list::const_iterator q
;
4785 for (q
= rpath
.begin(); q
!= p
; ++q
)
4786 if (q
->name() == p
->name())
4791 rpath_val
+= p
->name();
4796 if (!parameters
->options().enable_new_dtags())
4797 odyn
->add_string(elfcpp::DT_RPATH
, rpath_val
);
4799 odyn
->add_string(elfcpp::DT_RUNPATH
, rpath_val
);
4802 // Look for text segments that have dynamic relocations.
4803 bool have_textrel
= false;
4804 if (!this->script_options_
->saw_sections_clause())
4806 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
4807 p
!= this->segment_list_
.end();
4810 if ((*p
)->type() == elfcpp::PT_LOAD
4811 && ((*p
)->flags() & elfcpp::PF_W
) == 0
4812 && (*p
)->has_dynamic_reloc())
4814 have_textrel
= true;
4821 // We don't know the section -> segment mapping, so we are
4822 // conservative and just look for readonly sections with
4823 // relocations. If those sections wind up in writable segments,
4824 // then we have created an unnecessary DT_TEXTREL entry.
4825 for (Section_list::const_iterator p
= this->section_list_
.begin();
4826 p
!= this->section_list_
.end();
4829 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) != 0
4830 && ((*p
)->flags() & elfcpp::SHF_WRITE
) == 0
4831 && (*p
)->has_dynamic_reloc())
4833 have_textrel
= true;
4839 if (parameters
->options().filter() != NULL
)
4840 odyn
->add_string(elfcpp::DT_FILTER
, parameters
->options().filter());
4841 if (parameters
->options().any_auxiliary())
4843 for (options::String_set::const_iterator p
=
4844 parameters
->options().auxiliary_begin();
4845 p
!= parameters
->options().auxiliary_end();
4847 odyn
->add_string(elfcpp::DT_AUXILIARY
, *p
);
4850 // Add a DT_FLAGS entry if necessary.
4851 unsigned int flags
= 0;
4854 // Add a DT_TEXTREL for compatibility with older loaders.
4855 odyn
->add_constant(elfcpp::DT_TEXTREL
, 0);
4856 flags
|= elfcpp::DF_TEXTREL
;
4858 if (parameters
->options().text())
4859 gold_error(_("read-only segment has dynamic relocations"));
4860 else if (parameters
->options().warn_shared_textrel()
4861 && parameters
->options().shared())
4862 gold_warning(_("shared library text segment is not shareable"));
4864 if (parameters
->options().shared() && this->has_static_tls())
4865 flags
|= elfcpp::DF_STATIC_TLS
;
4866 if (parameters
->options().origin())
4867 flags
|= elfcpp::DF_ORIGIN
;
4868 if (parameters
->options().Bsymbolic())
4870 flags
|= elfcpp::DF_SYMBOLIC
;
4871 // Add DT_SYMBOLIC for compatibility with older loaders.
4872 odyn
->add_constant(elfcpp::DT_SYMBOLIC
, 0);
4874 if (parameters
->options().now())
4875 flags
|= elfcpp::DF_BIND_NOW
;
4877 odyn
->add_constant(elfcpp::DT_FLAGS
, flags
);
4880 if (parameters
->options().initfirst())
4881 flags
|= elfcpp::DF_1_INITFIRST
;
4882 if (parameters
->options().interpose())
4883 flags
|= elfcpp::DF_1_INTERPOSE
;
4884 if (parameters
->options().loadfltr())
4885 flags
|= elfcpp::DF_1_LOADFLTR
;
4886 if (parameters
->options().nodefaultlib())
4887 flags
|= elfcpp::DF_1_NODEFLIB
;
4888 if (parameters
->options().nodelete())
4889 flags
|= elfcpp::DF_1_NODELETE
;
4890 if (parameters
->options().nodlopen())
4891 flags
|= elfcpp::DF_1_NOOPEN
;
4892 if (parameters
->options().nodump())
4893 flags
|= elfcpp::DF_1_NODUMP
;
4894 if (!parameters
->options().shared())
4895 flags
&= ~(elfcpp::DF_1_INITFIRST
4896 | elfcpp::DF_1_NODELETE
4897 | elfcpp::DF_1_NOOPEN
);
4898 if (parameters
->options().origin())
4899 flags
|= elfcpp::DF_1_ORIGIN
;
4900 if (parameters
->options().now())
4901 flags
|= elfcpp::DF_1_NOW
;
4902 if (parameters
->options().Bgroup())
4903 flags
|= elfcpp::DF_1_GROUP
;
4905 odyn
->add_constant(elfcpp::DT_FLAGS_1
, flags
);
4908 // Set the size of the _DYNAMIC symbol table to be the size of the
4912 Layout::set_dynamic_symbol_size(const Symbol_table
* symtab
)
4914 Output_data_dynamic
* const odyn
= this->dynamic_data_
;
4917 odyn
->finalize_data_size();
4918 if (this->dynamic_symbol_
== NULL
)
4920 off_t data_size
= odyn
->data_size();
4921 const int size
= parameters
->target().get_size();
4923 symtab
->get_sized_symbol
<32>(this->dynamic_symbol_
)->set_symsize(data_size
);
4924 else if (size
== 64)
4925 symtab
->get_sized_symbol
<64>(this->dynamic_symbol_
)->set_symsize(data_size
);
4930 // The mapping of input section name prefixes to output section names.
4931 // In some cases one prefix is itself a prefix of another prefix; in
4932 // such a case the longer prefix must come first. These prefixes are
4933 // based on the GNU linker default ELF linker script.
4935 #define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 }
4936 #define MAPPING_INIT_EXACT(f, t) { f, 0, t, sizeof(t) - 1 }
4937 const Layout::Section_name_mapping
Layout::section_name_mapping
[] =
4939 MAPPING_INIT(".text.", ".text"),
4940 MAPPING_INIT(".rodata.", ".rodata"),
4941 MAPPING_INIT(".data.rel.ro.local.", ".data.rel.ro.local"),
4942 MAPPING_INIT_EXACT(".data.rel.ro.local", ".data.rel.ro.local"),
4943 MAPPING_INIT(".data.rel.ro.", ".data.rel.ro"),
4944 MAPPING_INIT_EXACT(".data.rel.ro", ".data.rel.ro"),
4945 MAPPING_INIT(".data.", ".data"),
4946 MAPPING_INIT(".bss.", ".bss"),
4947 MAPPING_INIT(".tdata.", ".tdata"),
4948 MAPPING_INIT(".tbss.", ".tbss"),
4949 MAPPING_INIT(".init_array.", ".init_array"),
4950 MAPPING_INIT(".fini_array.", ".fini_array"),
4951 MAPPING_INIT(".sdata.", ".sdata"),
4952 MAPPING_INIT(".sbss.", ".sbss"),
4953 // FIXME: In the GNU linker, .sbss2 and .sdata2 are handled
4954 // differently depending on whether it is creating a shared library.
4955 MAPPING_INIT(".sdata2.", ".sdata"),
4956 MAPPING_INIT(".sbss2.", ".sbss"),
4957 MAPPING_INIT(".lrodata.", ".lrodata"),
4958 MAPPING_INIT(".ldata.", ".ldata"),
4959 MAPPING_INIT(".lbss.", ".lbss"),
4960 MAPPING_INIT(".gcc_except_table.", ".gcc_except_table"),
4961 MAPPING_INIT(".gnu.linkonce.d.rel.ro.local.", ".data.rel.ro.local"),
4962 MAPPING_INIT(".gnu.linkonce.d.rel.ro.", ".data.rel.ro"),
4963 MAPPING_INIT(".gnu.linkonce.t.", ".text"),
4964 MAPPING_INIT(".gnu.linkonce.r.", ".rodata"),
4965 MAPPING_INIT(".gnu.linkonce.d.", ".data"),
4966 MAPPING_INIT(".gnu.linkonce.b.", ".bss"),
4967 MAPPING_INIT(".gnu.linkonce.s.", ".sdata"),
4968 MAPPING_INIT(".gnu.linkonce.sb.", ".sbss"),
4969 MAPPING_INIT(".gnu.linkonce.s2.", ".sdata"),
4970 MAPPING_INIT(".gnu.linkonce.sb2.", ".sbss"),
4971 MAPPING_INIT(".gnu.linkonce.wi.", ".debug_info"),
4972 MAPPING_INIT(".gnu.linkonce.td.", ".tdata"),
4973 MAPPING_INIT(".gnu.linkonce.tb.", ".tbss"),
4974 MAPPING_INIT(".gnu.linkonce.lr.", ".lrodata"),
4975 MAPPING_INIT(".gnu.linkonce.l.", ".ldata"),
4976 MAPPING_INIT(".gnu.linkonce.lb.", ".lbss"),
4977 MAPPING_INIT(".ARM.extab", ".ARM.extab"),
4978 MAPPING_INIT(".gnu.linkonce.armextab.", ".ARM.extab"),
4979 MAPPING_INIT(".ARM.exidx", ".ARM.exidx"),
4980 MAPPING_INIT(".gnu.linkonce.armexidx.", ".ARM.exidx"),
4983 #undef MAPPING_INIT_EXACT
4985 const int Layout::section_name_mapping_count
=
4986 (sizeof(Layout::section_name_mapping
)
4987 / sizeof(Layout::section_name_mapping
[0]));
4989 // Choose the output section name to use given an input section name.
4990 // Set *PLEN to the length of the name. *PLEN is initialized to the
4994 Layout::output_section_name(const Relobj
* relobj
, const char* name
,
4997 // gcc 4.3 generates the following sorts of section names when it
4998 // needs a section name specific to a function:
5004 // .data.rel.local.FN
5006 // .data.rel.ro.local.FN
5013 // The GNU linker maps all of those to the part before the .FN,
5014 // except that .data.rel.local.FN is mapped to .data, and
5015 // .data.rel.ro.local.FN is mapped to .data.rel.ro. The sections
5016 // beginning with .data.rel.ro.local are grouped together.
5018 // For an anonymous namespace, the string FN can contain a '.'.
5020 // Also of interest: .rodata.strN.N, .rodata.cstN, both of which the
5021 // GNU linker maps to .rodata.
5023 // The .data.rel.ro sections are used with -z relro. The sections
5024 // are recognized by name. We use the same names that the GNU
5025 // linker does for these sections.
5027 // It is hard to handle this in a principled way, so we don't even
5028 // try. We use a table of mappings. If the input section name is
5029 // not found in the table, we simply use it as the output section
5032 const Section_name_mapping
* psnm
= section_name_mapping
;
5033 for (int i
= 0; i
< section_name_mapping_count
; ++i
, ++psnm
)
5035 if (psnm
->fromlen
> 0)
5037 if (strncmp(name
, psnm
->from
, psnm
->fromlen
) == 0)
5039 *plen
= psnm
->tolen
;
5045 if (strcmp(name
, psnm
->from
) == 0)
5047 *plen
= psnm
->tolen
;
5053 // As an additional complication, .ctors sections are output in
5054 // either .ctors or .init_array sections, and .dtors sections are
5055 // output in either .dtors or .fini_array sections.
5056 if (is_prefix_of(".ctors.", name
) || is_prefix_of(".dtors.", name
))
5058 if (parameters
->options().ctors_in_init_array())
5061 return name
[1] == 'c' ? ".init_array" : ".fini_array";
5066 return name
[1] == 'c' ? ".ctors" : ".dtors";
5069 if (parameters
->options().ctors_in_init_array()
5070 && (strcmp(name
, ".ctors") == 0 || strcmp(name
, ".dtors") == 0))
5072 // To make .init_array/.fini_array work with gcc we must exclude
5073 // .ctors and .dtors sections from the crtbegin and crtend
5076 || (!Layout::match_file_name(relobj
, "crtbegin")
5077 && !Layout::match_file_name(relobj
, "crtend")))
5080 return name
[1] == 'c' ? ".init_array" : ".fini_array";
5087 // Return true if RELOBJ is an input file whose base name matches
5088 // FILE_NAME. The base name must have an extension of ".o", and must
5089 // be exactly FILE_NAME.o or FILE_NAME, one character, ".o". This is
5090 // to match crtbegin.o as well as crtbeginS.o without getting confused
5091 // by other possibilities. Overall matching the file name this way is
5092 // a dreadful hack, but the GNU linker does it in order to better
5093 // support gcc, and we need to be compatible.
5096 Layout::match_file_name(const Relobj
* relobj
, const char* match
)
5098 const std::string
& file_name(relobj
->name());
5099 const char* base_name
= lbasename(file_name
.c_str());
5100 size_t match_len
= strlen(match
);
5101 if (strncmp(base_name
, match
, match_len
) != 0)
5103 size_t base_len
= strlen(base_name
);
5104 if (base_len
!= match_len
+ 2 && base_len
!= match_len
+ 3)
5106 return memcmp(base_name
+ base_len
- 2, ".o", 2) == 0;
5109 // Check if a comdat group or .gnu.linkonce section with the given
5110 // NAME is selected for the link. If there is already a section,
5111 // *KEPT_SECTION is set to point to the existing section and the
5112 // function returns false. Otherwise, OBJECT, SHNDX, IS_COMDAT, and
5113 // IS_GROUP_NAME are recorded for this NAME in the layout object,
5114 // *KEPT_SECTION is set to the internal copy and the function returns
5118 Layout::find_or_add_kept_section(const std::string
& name
,
5123 Kept_section
** kept_section
)
5125 // It's normal to see a couple of entries here, for the x86 thunk
5126 // sections. If we see more than a few, we're linking a C++
5127 // program, and we resize to get more space to minimize rehashing.
5128 if (this->signatures_
.size() > 4
5129 && !this->resized_signatures_
)
5131 reserve_unordered_map(&this->signatures_
,
5132 this->number_of_input_files_
* 64);
5133 this->resized_signatures_
= true;
5136 Kept_section candidate
;
5137 std::pair
<Signatures::iterator
, bool> ins
=
5138 this->signatures_
.insert(std::make_pair(name
, candidate
));
5140 if (kept_section
!= NULL
)
5141 *kept_section
= &ins
.first
->second
;
5144 // This is the first time we've seen this signature.
5145 ins
.first
->second
.set_object(object
);
5146 ins
.first
->second
.set_shndx(shndx
);
5148 ins
.first
->second
.set_is_comdat();
5150 ins
.first
->second
.set_is_group_name();
5154 // We have already seen this signature.
5156 if (ins
.first
->second
.is_group_name())
5158 // We've already seen a real section group with this signature.
5159 // If the kept group is from a plugin object, and we're in the
5160 // replacement phase, accept the new one as a replacement.
5161 if (ins
.first
->second
.object() == NULL
5162 && parameters
->options().plugins()->in_replacement_phase())
5164 ins
.first
->second
.set_object(object
);
5165 ins
.first
->second
.set_shndx(shndx
);
5170 else if (is_group_name
)
5172 // This is a real section group, and we've already seen a
5173 // linkonce section with this signature. Record that we've seen
5174 // a section group, and don't include this section group.
5175 ins
.first
->second
.set_is_group_name();
5180 // We've already seen a linkonce section and this is a linkonce
5181 // section. These don't block each other--this may be the same
5182 // symbol name with different section types.
5187 // Store the allocated sections into the section list.
5190 Layout::get_allocated_sections(Section_list
* section_list
) const
5192 for (Section_list::const_iterator p
= this->section_list_
.begin();
5193 p
!= this->section_list_
.end();
5195 if (((*p
)->flags() & elfcpp::SHF_ALLOC
) != 0)
5196 section_list
->push_back(*p
);
5199 // Store the executable sections into the section list.
5202 Layout::get_executable_sections(Section_list
* section_list
) const
5204 for (Section_list::const_iterator p
= this->section_list_
.begin();
5205 p
!= this->section_list_
.end();
5207 if (((*p
)->flags() & (elfcpp::SHF_ALLOC
| elfcpp::SHF_EXECINSTR
))
5208 == (elfcpp::SHF_ALLOC
| elfcpp::SHF_EXECINSTR
))
5209 section_list
->push_back(*p
);
5212 // Create an output segment.
5215 Layout::make_output_segment(elfcpp::Elf_Word type
, elfcpp::Elf_Word flags
)
5217 gold_assert(!parameters
->options().relocatable());
5218 Output_segment
* oseg
= new Output_segment(type
, flags
);
5219 this->segment_list_
.push_back(oseg
);
5221 if (type
== elfcpp::PT_TLS
)
5222 this->tls_segment_
= oseg
;
5223 else if (type
== elfcpp::PT_GNU_RELRO
)
5224 this->relro_segment_
= oseg
;
5225 else if (type
== elfcpp::PT_INTERP
)
5226 this->interp_segment_
= oseg
;
5231 // Return the file offset of the normal symbol table.
5234 Layout::symtab_section_offset() const
5236 if (this->symtab_section_
!= NULL
)
5237 return this->symtab_section_
->offset();
5241 // Return the section index of the normal symbol table. It may have
5242 // been stripped by the -s/--strip-all option.
5245 Layout::symtab_section_shndx() const
5247 if (this->symtab_section_
!= NULL
)
5248 return this->symtab_section_
->out_shndx();
5252 // Write out the Output_sections. Most won't have anything to write,
5253 // since most of the data will come from input sections which are
5254 // handled elsewhere. But some Output_sections do have Output_data.
5257 Layout::write_output_sections(Output_file
* of
) const
5259 for (Section_list::const_iterator p
= this->section_list_
.begin();
5260 p
!= this->section_list_
.end();
5263 if (!(*p
)->after_input_sections())
5268 // Write out data not associated with a section or the symbol table.
5271 Layout::write_data(const Symbol_table
* symtab
, Output_file
* of
) const
5273 if (!parameters
->options().strip_all())
5275 const Output_section
* symtab_section
= this->symtab_section_
;
5276 for (Section_list::const_iterator p
= this->section_list_
.begin();
5277 p
!= this->section_list_
.end();
5280 if ((*p
)->needs_symtab_index())
5282 gold_assert(symtab_section
!= NULL
);
5283 unsigned int index
= (*p
)->symtab_index();
5284 gold_assert(index
> 0 && index
!= -1U);
5285 off_t off
= (symtab_section
->offset()
5286 + index
* symtab_section
->entsize());
5287 symtab
->write_section_symbol(*p
, this->symtab_xindex_
, of
, off
);
5292 const Output_section
* dynsym_section
= this->dynsym_section_
;
5293 for (Section_list::const_iterator p
= this->section_list_
.begin();
5294 p
!= this->section_list_
.end();
5297 if ((*p
)->needs_dynsym_index())
5299 gold_assert(dynsym_section
!= NULL
);
5300 unsigned int index
= (*p
)->dynsym_index();
5301 gold_assert(index
> 0 && index
!= -1U);
5302 off_t off
= (dynsym_section
->offset()
5303 + index
* dynsym_section
->entsize());
5304 symtab
->write_section_symbol(*p
, this->dynsym_xindex_
, of
, off
);
5308 // Write out the Output_data which are not in an Output_section.
5309 for (Data_list::const_iterator p
= this->special_output_list_
.begin();
5310 p
!= this->special_output_list_
.end();
5314 // Write out the Output_data which are not in an Output_section
5315 // and are regenerated in each iteration of relaxation.
5316 for (Data_list::const_iterator p
= this->relax_output_list_
.begin();
5317 p
!= this->relax_output_list_
.end();
5322 // Write out the Output_sections which can only be written after the
5323 // input sections are complete.
5326 Layout::write_sections_after_input_sections(Output_file
* of
)
5328 // Determine the final section offsets, and thus the final output
5329 // file size. Note we finalize the .shstrab last, to allow the
5330 // after_input_section sections to modify their section-names before
5332 if (this->any_postprocessing_sections_
)
5334 off_t off
= this->output_file_size_
;
5335 off
= this->set_section_offsets(off
, POSTPROCESSING_SECTIONS_PASS
);
5337 // Now that we've finalized the names, we can finalize the shstrab.
5339 this->set_section_offsets(off
,
5340 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
);
5342 if (off
> this->output_file_size_
)
5345 this->output_file_size_
= off
;
5349 for (Section_list::const_iterator p
= this->section_list_
.begin();
5350 p
!= this->section_list_
.end();
5353 if ((*p
)->after_input_sections())
5357 this->section_headers_
->write(of
);
5360 // Build IDs can be computed as a "flat" sha1 or md5 of a string of bytes,
5361 // or as a "tree" where each chunk of the string is hashed and then those
5362 // hashes are put into a (much smaller) string which is hashed with sha1.
5363 // We compute a checksum over the entire file because that is simplest.
5366 Layout::queue_build_id_tasks(Workqueue
* workqueue
, Task_token
* build_id_blocker
,
5369 const size_t filesize
= (this->output_file_size() <= 0 ? 0
5370 : static_cast<size_t>(this->output_file_size()));
5371 if (this->build_id_note_
!= NULL
5372 && strcmp(parameters
->options().build_id(), "tree") == 0
5373 && parameters
->options().build_id_chunk_size_for_treehash() > 0
5376 parameters
->options().build_id_min_file_size_for_treehash()))
5378 static const size_t MD5_OUTPUT_SIZE_IN_BYTES
= 16;
5379 const size_t chunk_size
=
5380 parameters
->options().build_id_chunk_size_for_treehash();
5381 const size_t num_hashes
= ((filesize
- 1) / chunk_size
) + 1;
5382 Task_token
* post_hash_tasks_blocker
= new Task_token(true);
5383 post_hash_tasks_blocker
->add_blockers(num_hashes
);
5384 this->size_of_array_of_hashes_
= num_hashes
* MD5_OUTPUT_SIZE_IN_BYTES
;
5385 const unsigned char* src
= of
->get_input_view(0, filesize
);
5386 this->input_view_
= src
;
5387 unsigned char *dst
= new unsigned char[this->size_of_array_of_hashes_
];
5388 this->array_of_hashes_
= dst
;
5389 for (size_t i
= 0, src_offset
= 0; i
< num_hashes
;
5390 i
++, dst
+= MD5_OUTPUT_SIZE_IN_BYTES
, src_offset
+= chunk_size
)
5392 size_t size
= std::min(chunk_size
, filesize
- src_offset
);
5393 workqueue
->queue(new Hash_task(src
+ src_offset
,
5397 post_hash_tasks_blocker
));
5399 return post_hash_tasks_blocker
;
5401 return build_id_blocker
;
5404 // If a tree-style build ID was requested, the parallel part of that computation
5405 // is already done, and the final hash-of-hashes is computed here. For other
5406 // types of build IDs, all the work is done here.
5409 Layout::write_build_id(Output_file
* of
) const
5411 if (this->build_id_note_
== NULL
)
5414 unsigned char* ov
= of
->get_output_view(this->build_id_note_
->offset(),
5415 this->build_id_note_
->data_size());
5417 if (this->array_of_hashes_
== NULL
)
5419 const size_t output_file_size
= this->output_file_size();
5420 const unsigned char* iv
= of
->get_input_view(0, output_file_size
);
5421 const char* style
= parameters
->options().build_id();
5423 // If we get here with style == "tree" then the output must be
5424 // too small for chunking, and we use SHA-1 in that case.
5425 if ((strcmp(style
, "sha1") == 0) || (strcmp(style
, "tree") == 0))
5426 sha1_buffer(reinterpret_cast<const char*>(iv
), output_file_size
, ov
);
5427 else if (strcmp(style
, "md5") == 0)
5428 md5_buffer(reinterpret_cast<const char*>(iv
), output_file_size
, ov
);
5432 of
->free_input_view(0, output_file_size
, iv
);
5436 // Non-overlapping substrings of the output file have been hashed.
5437 // Compute SHA-1 hash of the hashes.
5438 sha1_buffer(reinterpret_cast<const char*>(this->array_of_hashes_
),
5439 this->size_of_array_of_hashes_
, ov
);
5440 delete[] this->array_of_hashes_
;
5441 of
->free_input_view(0, this->output_file_size(), this->input_view_
);
5444 of
->write_output_view(this->build_id_note_
->offset(),
5445 this->build_id_note_
->data_size(),
5449 // Write out a binary file. This is called after the link is
5450 // complete. IN is the temporary output file we used to generate the
5451 // ELF code. We simply walk through the segments, read them from
5452 // their file offset in IN, and write them to their load address in
5453 // the output file. FIXME: with a bit more work, we could support
5454 // S-records and/or Intel hex format here.
5457 Layout::write_binary(Output_file
* in
) const
5459 gold_assert(parameters
->options().oformat_enum()
5460 == General_options::OBJECT_FORMAT_BINARY
);
5462 // Get the size of the binary file.
5463 uint64_t max_load_address
= 0;
5464 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
5465 p
!= this->segment_list_
.end();
5468 if ((*p
)->type() == elfcpp::PT_LOAD
&& (*p
)->filesz() > 0)
5470 uint64_t max_paddr
= (*p
)->paddr() + (*p
)->filesz();
5471 if (max_paddr
> max_load_address
)
5472 max_load_address
= max_paddr
;
5476 Output_file
out(parameters
->options().output_file_name());
5477 out
.open(max_load_address
);
5479 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
5480 p
!= this->segment_list_
.end();
5483 if ((*p
)->type() == elfcpp::PT_LOAD
&& (*p
)->filesz() > 0)
5485 const unsigned char* vin
= in
->get_input_view((*p
)->offset(),
5487 unsigned char* vout
= out
.get_output_view((*p
)->paddr(),
5489 memcpy(vout
, vin
, (*p
)->filesz());
5490 out
.write_output_view((*p
)->paddr(), (*p
)->filesz(), vout
);
5491 in
->free_input_view((*p
)->offset(), (*p
)->filesz(), vin
);
5498 // Print the output sections to the map file.
5501 Layout::print_to_mapfile(Mapfile
* mapfile
) const
5503 for (Segment_list::const_iterator p
= this->segment_list_
.begin();
5504 p
!= this->segment_list_
.end();
5506 (*p
)->print_sections_to_mapfile(mapfile
);
5507 for (Section_list::const_iterator p
= this->unattached_section_list_
.begin();
5508 p
!= this->unattached_section_list_
.end();
5510 (*p
)->print_to_mapfile(mapfile
);
5513 // Print statistical information to stderr. This is used for --stats.
5516 Layout::print_stats() const
5518 this->namepool_
.print_stats("section name pool");
5519 this->sympool_
.print_stats("output symbol name pool");
5520 this->dynpool_
.print_stats("dynamic name pool");
5522 for (Section_list::const_iterator p
= this->section_list_
.begin();
5523 p
!= this->section_list_
.end();
5525 (*p
)->print_merge_stats();
5528 // Write_sections_task methods.
5530 // We can always run this task.
5533 Write_sections_task::is_runnable()
5538 // We need to unlock both OUTPUT_SECTIONS_BLOCKER and FINAL_BLOCKER
5542 Write_sections_task::locks(Task_locker
* tl
)
5544 tl
->add(this, this->output_sections_blocker_
);
5545 if (this->input_sections_blocker_
!= NULL
)
5546 tl
->add(this, this->input_sections_blocker_
);
5547 tl
->add(this, this->final_blocker_
);
5550 // Run the task--write out the data.
5553 Write_sections_task::run(Workqueue
*)
5555 this->layout_
->write_output_sections(this->of_
);
5558 // Write_data_task methods.
5560 // We can always run this task.
5563 Write_data_task::is_runnable()
5568 // We need to unlock FINAL_BLOCKER when finished.
5571 Write_data_task::locks(Task_locker
* tl
)
5573 tl
->add(this, this->final_blocker_
);
5576 // Run the task--write out the data.
5579 Write_data_task::run(Workqueue
*)
5581 this->layout_
->write_data(this->symtab_
, this->of_
);
5584 // Write_symbols_task methods.
5586 // We can always run this task.
5589 Write_symbols_task::is_runnable()
5594 // We need to unlock FINAL_BLOCKER when finished.
5597 Write_symbols_task::locks(Task_locker
* tl
)
5599 tl
->add(this, this->final_blocker_
);
5602 // Run the task--write out the symbols.
5605 Write_symbols_task::run(Workqueue
*)
5607 this->symtab_
->write_globals(this->sympool_
, this->dynpool_
,
5608 this->layout_
->symtab_xindex(),
5609 this->layout_
->dynsym_xindex(), this->of_
);
5612 // Write_after_input_sections_task methods.
5614 // We can only run this task after the input sections have completed.
5617 Write_after_input_sections_task::is_runnable()
5619 if (this->input_sections_blocker_
->is_blocked())
5620 return this->input_sections_blocker_
;
5624 // We need to unlock FINAL_BLOCKER when finished.
5627 Write_after_input_sections_task::locks(Task_locker
* tl
)
5629 tl
->add(this, this->final_blocker_
);
5635 Write_after_input_sections_task::run(Workqueue
*)
5637 this->layout_
->write_sections_after_input_sections(this->of_
);
5640 // Close_task_runner methods.
5642 // Finish up the build ID computation, if necessary, and write a binary file,
5643 // if necessary. Then close the output file.
5646 Close_task_runner::run(Workqueue
*, const Task
*)
5648 // At this point the multi-threaded part of the build ID computation,
5649 // if any, is done. See queue_build_id_tasks().
5650 this->layout_
->write_build_id(this->of_
);
5652 // If we've been asked to create a binary file, we do so here.
5653 if (this->options_
->oformat_enum() != General_options::OBJECT_FORMAT_ELF
)
5654 this->layout_
->write_binary(this->of_
);
5659 // Instantiate the templates we need. We could use the configure
5660 // script to restrict this to only the ones for implemented targets.
5662 #ifdef HAVE_TARGET_32_LITTLE
5665 Layout::init_fixed_output_section
<32, false>(
5667 elfcpp::Shdr
<32, false>& shdr
);
5670 #ifdef HAVE_TARGET_32_BIG
5673 Layout::init_fixed_output_section
<32, true>(
5675 elfcpp::Shdr
<32, true>& shdr
);
5678 #ifdef HAVE_TARGET_64_LITTLE
5681 Layout::init_fixed_output_section
<64, false>(
5683 elfcpp::Shdr
<64, false>& shdr
);
5686 #ifdef HAVE_TARGET_64_BIG
5689 Layout::init_fixed_output_section
<64, true>(
5691 elfcpp::Shdr
<64, true>& shdr
);
5694 #ifdef HAVE_TARGET_32_LITTLE
5697 Layout::layout
<32, false>(Sized_relobj_file
<32, false>* object
,
5700 const elfcpp::Shdr
<32, false>& shdr
,
5701 unsigned int, unsigned int, off_t
*);
5704 #ifdef HAVE_TARGET_32_BIG
5707 Layout::layout
<32, true>(Sized_relobj_file
<32, true>* object
,
5710 const elfcpp::Shdr
<32, true>& shdr
,
5711 unsigned int, unsigned int, off_t
*);
5714 #ifdef HAVE_TARGET_64_LITTLE
5717 Layout::layout
<64, false>(Sized_relobj_file
<64, false>* object
,
5720 const elfcpp::Shdr
<64, false>& shdr
,
5721 unsigned int, unsigned int, off_t
*);
5724 #ifdef HAVE_TARGET_64_BIG
5727 Layout::layout
<64, true>(Sized_relobj_file
<64, true>* object
,
5730 const elfcpp::Shdr
<64, true>& shdr
,
5731 unsigned int, unsigned int, off_t
*);
5734 #ifdef HAVE_TARGET_32_LITTLE
5737 Layout::layout_reloc
<32, false>(Sized_relobj_file
<32, false>* object
,
5738 unsigned int reloc_shndx
,
5739 const elfcpp::Shdr
<32, false>& shdr
,
5740 Output_section
* data_section
,
5741 Relocatable_relocs
* rr
);
5744 #ifdef HAVE_TARGET_32_BIG
5747 Layout::layout_reloc
<32, true>(Sized_relobj_file
<32, true>* object
,
5748 unsigned int reloc_shndx
,
5749 const elfcpp::Shdr
<32, true>& shdr
,
5750 Output_section
* data_section
,
5751 Relocatable_relocs
* rr
);
5754 #ifdef HAVE_TARGET_64_LITTLE
5757 Layout::layout_reloc
<64, false>(Sized_relobj_file
<64, false>* object
,
5758 unsigned int reloc_shndx
,
5759 const elfcpp::Shdr
<64, false>& shdr
,
5760 Output_section
* data_section
,
5761 Relocatable_relocs
* rr
);
5764 #ifdef HAVE_TARGET_64_BIG
5767 Layout::layout_reloc
<64, true>(Sized_relobj_file
<64, true>* object
,
5768 unsigned int reloc_shndx
,
5769 const elfcpp::Shdr
<64, true>& shdr
,
5770 Output_section
* data_section
,
5771 Relocatable_relocs
* rr
);
5774 #ifdef HAVE_TARGET_32_LITTLE
5777 Layout::layout_group
<32, false>(Symbol_table
* symtab
,
5778 Sized_relobj_file
<32, false>* object
,
5780 const char* group_section_name
,
5781 const char* signature
,
5782 const elfcpp::Shdr
<32, false>& shdr
,
5783 elfcpp::Elf_Word flags
,
5784 std::vector
<unsigned int>* shndxes
);
5787 #ifdef HAVE_TARGET_32_BIG
5790 Layout::layout_group
<32, true>(Symbol_table
* symtab
,
5791 Sized_relobj_file
<32, true>* object
,
5793 const char* group_section_name
,
5794 const char* signature
,
5795 const elfcpp::Shdr
<32, true>& shdr
,
5796 elfcpp::Elf_Word flags
,
5797 std::vector
<unsigned int>* shndxes
);
5800 #ifdef HAVE_TARGET_64_LITTLE
5803 Layout::layout_group
<64, false>(Symbol_table
* symtab
,
5804 Sized_relobj_file
<64, false>* object
,
5806 const char* group_section_name
,
5807 const char* signature
,
5808 const elfcpp::Shdr
<64, false>& shdr
,
5809 elfcpp::Elf_Word flags
,
5810 std::vector
<unsigned int>* shndxes
);
5813 #ifdef HAVE_TARGET_64_BIG
5816 Layout::layout_group
<64, true>(Symbol_table
* symtab
,
5817 Sized_relobj_file
<64, true>* object
,
5819 const char* group_section_name
,
5820 const char* signature
,
5821 const elfcpp::Shdr
<64, true>& shdr
,
5822 elfcpp::Elf_Word flags
,
5823 std::vector
<unsigned int>* shndxes
);
5826 #ifdef HAVE_TARGET_32_LITTLE
5829 Layout::layout_eh_frame
<32, false>(Sized_relobj_file
<32, false>* object
,
5830 const unsigned char* symbols
,
5832 const unsigned char* symbol_names
,
5833 off_t symbol_names_size
,
5835 const elfcpp::Shdr
<32, false>& shdr
,
5836 unsigned int reloc_shndx
,
5837 unsigned int reloc_type
,
5841 #ifdef HAVE_TARGET_32_BIG
5844 Layout::layout_eh_frame
<32, true>(Sized_relobj_file
<32, true>* object
,
5845 const unsigned char* symbols
,
5847 const unsigned char* symbol_names
,
5848 off_t symbol_names_size
,
5850 const elfcpp::Shdr
<32, true>& shdr
,
5851 unsigned int reloc_shndx
,
5852 unsigned int reloc_type
,
5856 #ifdef HAVE_TARGET_64_LITTLE
5859 Layout::layout_eh_frame
<64, false>(Sized_relobj_file
<64, false>* object
,
5860 const unsigned char* symbols
,
5862 const unsigned char* symbol_names
,
5863 off_t symbol_names_size
,
5865 const elfcpp::Shdr
<64, false>& shdr
,
5866 unsigned int reloc_shndx
,
5867 unsigned int reloc_type
,
5871 #ifdef HAVE_TARGET_64_BIG
5874 Layout::layout_eh_frame
<64, true>(Sized_relobj_file
<64, true>* object
,
5875 const unsigned char* symbols
,
5877 const unsigned char* symbol_names
,
5878 off_t symbol_names_size
,
5880 const elfcpp::Shdr
<64, true>& shdr
,
5881 unsigned int reloc_shndx
,
5882 unsigned int reloc_type
,
5886 #ifdef HAVE_TARGET_32_LITTLE
5889 Layout::add_to_gdb_index(bool is_type_unit
,
5890 Sized_relobj
<32, false>* object
,
5891 const unsigned char* symbols
,
5894 unsigned int reloc_shndx
,
5895 unsigned int reloc_type
);
5898 #ifdef HAVE_TARGET_32_BIG
5901 Layout::add_to_gdb_index(bool is_type_unit
,
5902 Sized_relobj
<32, true>* object
,
5903 const unsigned char* symbols
,
5906 unsigned int reloc_shndx
,
5907 unsigned int reloc_type
);
5910 #ifdef HAVE_TARGET_64_LITTLE
5913 Layout::add_to_gdb_index(bool is_type_unit
,
5914 Sized_relobj
<64, false>* object
,
5915 const unsigned char* symbols
,
5918 unsigned int reloc_shndx
,
5919 unsigned int reloc_type
);
5922 #ifdef HAVE_TARGET_64_BIG
5925 Layout::add_to_gdb_index(bool is_type_unit
,
5926 Sized_relobj
<64, true>* object
,
5927 const unsigned char* symbols
,
5930 unsigned int reloc_shndx
,
5931 unsigned int reloc_type
);
5934 } // End namespace gold.