1 // layout.cc -- lay out output file sections for gold
2
3 // Copyright (C) 2006-2016 Free Software Foundation, Inc.
4 // Written by Ian Lance Taylor <iant@google.com>.
5
6 // This file is part of gold.
7
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.
12
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.
17
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.
22
23 #include "gold.h"
24
25 #include <cerrno>
26 #include <cstring>
27 #include <algorithm>
28 #include <iostream>
29 #include <fstream>
30 #include <utility>
31 #include <fcntl.h>
32 #include <fnmatch.h>
33 #include <unistd.h>
34 #include "libiberty.h"
35 #include "md5.h"
36 #include "sha1.h"
37
38 #include "parameters.h"
39 #include "options.h"
40 #include "mapfile.h"
41 #include "script.h"
42 #include "script-sections.h"
43 #include "output.h"
44 #include "symtab.h"
45 #include "dynobj.h"
46 #include "ehframe.h"
47 #include "gdb-index.h"
48 #include "compressed_output.h"
49 #include "reduced_debug_output.h"
50 #include "object.h"
51 #include "reloc.h"
52 #include "descriptors.h"
53 #include "plugin.h"
54 #include "incremental.h"
55 #include "layout.h"
56
57 namespace gold
58 {
59
60 // Class Free_list.
61
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;
74
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
78 // length.
79
80 void
init(off_t len,bool extend)81 Free_list::init(off_t len, bool extend)
82 {
83 this->list_.push_front(Free_list_node(0, len));
84 this->last_remove_ = this->list_.begin();
85 this->extend_ = extend;
86 this->length_ = len;
87 ++Free_list::num_lists;
88 ++Free_list::num_nodes;
89 }
90
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
98 // performance.
99
100 void
remove(off_t start,off_t end)101 Free_list::remove(off_t start, off_t end)
102 {
103 if (start == end)
104 return;
105 gold_assert(start < end);
106
107 ++Free_list::num_removes;
108
109 Iterator p = this->last_remove_;
110 if (p->start_ > start)
111 p = this->list_.begin();
112
113 for (; p != this->list_.end(); ++p)
114 {
115 ++Free_list::num_remove_visits;
116 // Find a node that wholly contains the indicated region.
117 if (p->start_ <= start && p->end_ >= end)
118 {
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)
125 p->start_ = end;
126 // Case 3: remove a chunk from the end of the node.
127 else if (p->end_ <= end + 3)
128 p->end_ = start;
129 // Case 4: remove a chunk from the middle, and split
130 // the node into two.
131 else
132 {
133 Free_list_node newnode(p->start_, start);
134 p->start_ = end;
135 this->list_.insert(p, newnode);
136 ++Free_list::num_nodes;
137 }
138 this->last_remove_ = p;
139 return;
140 }
141 }
142
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));
148 }
149
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.
153
154 off_t
allocate(off_t len,uint64_t align,off_t minoff)155 Free_list::allocate(off_t len, uint64_t align, off_t minoff)
156 {
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));
161 if (len == 0)
162 return align_address(minoff, align);
163
164 ++Free_list::num_allocates;
165
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;
170
171 for (Iterator p = this->list_.begin(); p != this->list_.end(); ++p)
172 {
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_)
178 {
179 this->length_ = end;
180 p->end_ = end;
181 }
182 if (end == p->end_ || (end <= p->end_ - this->min_hole_))
183 {
184 if (p->start_ + fuzz >= start && p->end_ <= end + fuzz)
185 this->list_.erase(p);
186 else if (p->start_ + fuzz >= start)
187 p->start_ = end;
188 else if (p->end_ <= end + fuzz)
189 p->end_ = start;
190 else
191 {
192 Free_list_node newnode(p->start_, start);
193 p->start_ = end;
194 this->list_.insert(p, newnode);
195 ++Free_list::num_nodes;
196 }
197 return start;
198 }
199 }
200 if (this->extend_)
201 {
202 off_t start = align_address(this->length_, align);
203 this->length_ = start + len;
204 return start;
205 }
206 return -1;
207 }
208
209 // Dump the free list (for debugging).
210 void
dump()211 Free_list::dump()
212 {
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_));
218 }
219
220 // Print the statistics for the free lists.
221 void
print_stats()222 Free_list::print_stats()
223 {
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);
236 }
237
238 // A Hash_task computes the MD5 checksum of an array of char.
239
240 class Hash_task : public Task
241 {
242 public:
Hash_task(Output_file * of,size_t offset,size_t size,unsigned char * dst,Task_token * final_blocker)243 Hash_task(Output_file* of,
244 size_t offset,
245 size_t size,
246 unsigned char* dst,
247 Task_token* final_blocker)
248 : of_(of), offset_(offset), size_(size), dst_(dst),
249 final_blocker_(final_blocker)
250 { }
251
252 void
run(Workqueue *)253 run(Workqueue*)
254 {
255 const unsigned char* iv =
256 this->of_->get_input_view(this->offset_, this->size_);
257 md5_buffer(reinterpret_cast<const char*>(iv), this->size_, this->dst_);
258 this->of_->free_input_view(this->offset_, this->size_, iv);
259 }
260
261 Task_token*
is_runnable()262 is_runnable()
263 { return NULL; }
264
265 // Unblock FINAL_BLOCKER_ when done.
266 void
locks(Task_locker * tl)267 locks(Task_locker* tl)
268 { tl->add(this, this->final_blocker_); }
269
270 std::string
get_name() const271 get_name() const
272 { return "Hash_task"; }
273
274 private:
275 Output_file* of_;
276 const size_t offset_;
277 const size_t size_;
278 unsigned char* const dst_;
279 Task_token* const final_blocker_;
280 };
281
282 // Layout::Relaxation_debug_check methods.
283
284 // Check that sections and special data are in reset states.
285 // We do not save states for Output_sections and special Output_data.
286 // So we check that they have not assigned any addresses or offsets.
287 // clean_up_after_relaxation simply resets their addresses and offsets.
288 void
check_output_data_for_reset_values(const Layout::Section_list & sections,const Layout::Data_list & special_outputs,const Layout::Data_list & relax_outputs)289 Layout::Relaxation_debug_check::check_output_data_for_reset_values(
290 const Layout::Section_list& sections,
291 const Layout::Data_list& special_outputs,
292 const Layout::Data_list& relax_outputs)
293 {
294 for(Layout::Section_list::const_iterator p = sections.begin();
295 p != sections.end();
296 ++p)
297 gold_assert((*p)->address_and_file_offset_have_reset_values());
298
299 for(Layout::Data_list::const_iterator p = special_outputs.begin();
300 p != special_outputs.end();
301 ++p)
302 gold_assert((*p)->address_and_file_offset_have_reset_values());
303
304 gold_assert(relax_outputs.empty());
305 }
306
307 // Save information of SECTIONS for checking later.
308
309 void
read_sections(const Layout::Section_list & sections)310 Layout::Relaxation_debug_check::read_sections(
311 const Layout::Section_list& sections)
312 {
313 for(Layout::Section_list::const_iterator p = sections.begin();
314 p != sections.end();
315 ++p)
316 {
317 Output_section* os = *p;
318 Section_info info;
319 info.output_section = os;
320 info.address = os->is_address_valid() ? os->address() : 0;
321 info.data_size = os->is_data_size_valid() ? os->data_size() : -1;
322 info.offset = os->is_offset_valid()? os->offset() : -1 ;
323 this->section_infos_.push_back(info);
324 }
325 }
326
327 // Verify SECTIONS using previously recorded information.
328
329 void
verify_sections(const Layout::Section_list & sections)330 Layout::Relaxation_debug_check::verify_sections(
331 const Layout::Section_list& sections)
332 {
333 size_t i = 0;
334 for(Layout::Section_list::const_iterator p = sections.begin();
335 p != sections.end();
336 ++p, ++i)
337 {
338 Output_section* os = *p;
339 uint64_t address = os->is_address_valid() ? os->address() : 0;
340 off_t data_size = os->is_data_size_valid() ? os->data_size() : -1;
341 off_t offset = os->is_offset_valid()? os->offset() : -1 ;
342
343 if (i >= this->section_infos_.size())
344 {
345 gold_fatal("Section_info of %s missing.\n", os->name());
346 }
347 const Section_info& info = this->section_infos_[i];
348 if (os != info.output_section)
349 gold_fatal("Section order changed. Expecting %s but see %s\n",
350 info.output_section->name(), os->name());
351 if (address != info.address
352 || data_size != info.data_size
353 || offset != info.offset)
354 gold_fatal("Section %s changed.\n", os->name());
355 }
356 }
357
358 // Layout_task_runner methods.
359
360 // Lay out the sections. This is called after all the input objects
361 // have been read.
362
363 void
run(Workqueue * workqueue,const Task * task)364 Layout_task_runner::run(Workqueue* workqueue, const Task* task)
365 {
366 // See if any of the input definitions violate the One Definition Rule.
367 // TODO: if this is too slow, do this as a task, rather than inline.
368 this->symtab_->detect_odr_violations(task, this->options_.output_file_name());
369
370 Layout* layout = this->layout_;
371 off_t file_size = layout->finalize(this->input_objects_,
372 this->symtab_,
373 this->target_,
374 task);
375
376 // Now we know the final size of the output file and we know where
377 // each piece of information goes.
378
379 if (this->mapfile_ != NULL)
380 {
381 this->mapfile_->print_discarded_sections(this->input_objects_);
382 layout->print_to_mapfile(this->mapfile_);
383 }
384
385 Output_file* of;
386 if (layout->incremental_base() == NULL)
387 {
388 of = new Output_file(parameters->options().output_file_name());
389 if (this->options_.oformat_enum() != General_options::OBJECT_FORMAT_ELF)
390 of->set_is_temporary();
391 of->open(file_size);
392 }
393 else
394 {
395 of = layout->incremental_base()->output_file();
396
397 // Apply the incremental relocations for symbols whose values
398 // have changed. We do this before we resize the file and start
399 // writing anything else to it, so that we can read the old
400 // incremental information from the file before (possibly)
401 // overwriting it.
402 if (parameters->incremental_update())
403 layout->incremental_base()->apply_incremental_relocs(this->symtab_,
404 this->layout_,
405 of);
406
407 of->resize(file_size);
408 }
409
410 // Queue up the final set of tasks.
411 gold::queue_final_tasks(this->options_, this->input_objects_,
412 this->symtab_, layout, workqueue, of);
413 }
414
415 // Layout methods.
416
Layout(int number_of_input_files,Script_options * script_options)417 Layout::Layout(int number_of_input_files, Script_options* script_options)
418 : number_of_input_files_(number_of_input_files),
419 script_options_(script_options),
420 namepool_(),
421 sympool_(),
422 dynpool_(),
423 signatures_(),
424 section_name_map_(),
425 segment_list_(),
426 section_list_(),
427 unattached_section_list_(),
428 special_output_list_(),
429 relax_output_list_(),
430 section_headers_(NULL),
431 tls_segment_(NULL),
432 relro_segment_(NULL),
433 interp_segment_(NULL),
434 increase_relro_(0),
435 symtab_section_(NULL),
436 symtab_xindex_(NULL),
437 dynsym_section_(NULL),
438 dynsym_xindex_(NULL),
439 dynamic_section_(NULL),
440 dynamic_symbol_(NULL),
441 dynamic_data_(NULL),
442 eh_frame_section_(NULL),
443 eh_frame_data_(NULL),
444 added_eh_frame_data_(false),
445 eh_frame_hdr_section_(NULL),
446 gdb_index_data_(NULL),
447 build_id_note_(NULL),
448 debug_abbrev_(NULL),
449 debug_info_(NULL),
450 group_signatures_(),
451 output_file_size_(-1),
452 have_added_input_section_(false),
453 sections_are_attached_(false),
454 input_requires_executable_stack_(false),
455 input_with_gnu_stack_note_(false),
456 input_without_gnu_stack_note_(false),
457 has_static_tls_(false),
458 any_postprocessing_sections_(false),
459 resized_signatures_(false),
460 have_stabstr_section_(false),
461 section_ordering_specified_(false),
462 unique_segment_for_sections_specified_(false),
463 incremental_inputs_(NULL),
464 record_output_section_data_from_script_(false),
465 script_output_section_data_list_(),
466 segment_states_(NULL),
467 relaxation_debug_check_(NULL),
468 section_order_map_(),
469 section_segment_map_(),
470 input_section_position_(),
471 input_section_glob_(),
472 incremental_base_(NULL),
473 free_list_()
474 {
475 // Make space for more than enough segments for a typical file.
476 // This is just for efficiency--it's OK if we wind up needing more.
477 this->segment_list_.reserve(12);
478
479 // We expect two unattached Output_data objects: the file header and
480 // the segment headers.
481 this->special_output_list_.reserve(2);
482
483 // Initialize structure needed for an incremental build.
484 if (parameters->incremental())
485 this->incremental_inputs_ = new Incremental_inputs;
486
487 // The section name pool is worth optimizing in all cases, because
488 // it is small, but there are often overlaps due to .rel sections.
489 this->namepool_.set_optimize();
490 }
491
492 // For incremental links, record the base file to be modified.
493
494 void
set_incremental_base(Incremental_binary * base)495 Layout::set_incremental_base(Incremental_binary* base)
496 {
497 this->incremental_base_ = base;
498 this->free_list_.init(base->output_file()->filesize(), true);
499 }
500
501 // Hash a key we use to look up an output section mapping.
502
503 size_t
operator ()(const Layout::Key & k) const504 Layout::Hash_key::operator()(const Layout::Key& k) const
505 {
506 return k.first + k.second.first + k.second.second;
507 }
508
509 // These are the debug sections that are actually used by gdb.
510 // Currently, we've checked versions of gdb up to and including 7.4.
511 // We only check the part of the name that follows ".debug_" or
512 // ".zdebug_".
513
514 static const char* gdb_sections[] =
515 {
516 "abbrev",
517 "addr", // Fission extension
518 // "aranges", // not used by gdb as of 7.4
519 "frame",
520 "gdb_scripts",
521 "info",
522 "types",
523 "line",
524 "loc",
525 "macinfo",
526 "macro",
527 // "pubnames", // not used by gdb as of 7.4
528 // "pubtypes", // not used by gdb as of 7.4
529 // "gnu_pubnames", // Fission extension
530 // "gnu_pubtypes", // Fission extension
531 "ranges",
532 "str",
533 "str_offsets",
534 };
535
536 // This is the minimum set of sections needed for line numbers.
537
538 static const char* lines_only_debug_sections[] =
539 {
540 "abbrev",
541 // "addr", // Fission extension
542 // "aranges", // not used by gdb as of 7.4
543 // "frame",
544 // "gdb_scripts",
545 "info",
546 // "types",
547 "line",
548 // "loc",
549 // "macinfo",
550 // "macro",
551 // "pubnames", // not used by gdb as of 7.4
552 // "pubtypes", // not used by gdb as of 7.4
553 // "gnu_pubnames", // Fission extension
554 // "gnu_pubtypes", // Fission extension
555 // "ranges",
556 "str",
557 "str_offsets", // Fission extension
558 };
559
560 // These sections are the DWARF fast-lookup tables, and are not needed
561 // when building a .gdb_index section.
562
563 static const char* gdb_fast_lookup_sections[] =
564 {
565 "aranges",
566 "pubnames",
567 "gnu_pubnames",
568 "pubtypes",
569 "gnu_pubtypes",
570 };
571
572 // Returns whether the given debug section is in the list of
573 // debug-sections-used-by-some-version-of-gdb. SUFFIX is the
574 // portion of the name following ".debug_" or ".zdebug_".
575
576 static inline bool
is_gdb_debug_section(const char * suffix)577 is_gdb_debug_section(const char* suffix)
578 {
579 // We can do this faster: binary search or a hashtable. But why bother?
580 for (size_t i = 0; i < sizeof(gdb_sections)/sizeof(*gdb_sections); ++i)
581 if (strcmp(suffix, gdb_sections[i]) == 0)
582 return true;
583 return false;
584 }
585
586 // Returns whether the given section is needed for lines-only debugging.
587
588 static inline bool
is_lines_only_debug_section(const char * suffix)589 is_lines_only_debug_section(const char* suffix)
590 {
591 // We can do this faster: binary search or a hashtable. But why bother?
592 for (size_t i = 0;
593 i < sizeof(lines_only_debug_sections)/sizeof(*lines_only_debug_sections);
594 ++i)
595 if (strcmp(suffix, lines_only_debug_sections[i]) == 0)
596 return true;
597 return false;
598 }
599
600 // Returns whether the given section is a fast-lookup section that
601 // will not be needed when building a .gdb_index section.
602
603 static inline bool
is_gdb_fast_lookup_section(const char * suffix)604 is_gdb_fast_lookup_section(const char* suffix)
605 {
606 // We can do this faster: binary search or a hashtable. But why bother?
607 for (size_t i = 0;
608 i < sizeof(gdb_fast_lookup_sections)/sizeof(*gdb_fast_lookup_sections);
609 ++i)
610 if (strcmp(suffix, gdb_fast_lookup_sections[i]) == 0)
611 return true;
612 return false;
613 }
614
615 // Sometimes we compress sections. This is typically done for
616 // sections that are not part of normal program execution (such as
617 // .debug_* sections), and where the readers of these sections know
618 // how to deal with compressed sections. This routine doesn't say for
619 // certain whether we'll compress -- it depends on commandline options
620 // as well -- just whether this section is a candidate for compression.
621 // (The Output_compressed_section class decides whether to compress
622 // a given section, and picks the name of the compressed section.)
623
624 static bool
is_compressible_debug_section(const char * secname)625 is_compressible_debug_section(const char* secname)
626 {
627 return (is_prefix_of(".debug", secname));
628 }
629
630 // We may see compressed debug sections in input files. Return TRUE
631 // if this is the name of a compressed debug section.
632
633 bool
is_compressed_debug_section(const char * secname)634 is_compressed_debug_section(const char* secname)
635 {
636 return (is_prefix_of(".zdebug", secname));
637 }
638
639 std::string
corresponding_uncompressed_section_name(std::string secname)640 corresponding_uncompressed_section_name(std::string secname)
641 {
642 gold_assert(secname[0] == '.' && secname[1] == 'z');
643 std::string ret(".");
644 ret.append(secname, 2, std::string::npos);
645 return ret;
646 }
647
648 // Whether to include this section in the link.
649
650 template<int size, bool big_endian>
651 bool
include_section(Sized_relobj_file<size,big_endian> *,const char * name,const elfcpp::Shdr<size,big_endian> & shdr)652 Layout::include_section(Sized_relobj_file<size, big_endian>*, const char* name,
653 const elfcpp::Shdr<size, big_endian>& shdr)
654 {
655 if (!parameters->options().relocatable()
656 && (shdr.get_sh_flags() & elfcpp::SHF_EXCLUDE))
657 return false;
658
659 elfcpp::Elf_Word sh_type = shdr.get_sh_type();
660
661 if ((sh_type >= elfcpp::SHT_LOOS && sh_type <= elfcpp::SHT_HIOS)
662 || (sh_type >= elfcpp::SHT_LOPROC && sh_type <= elfcpp::SHT_HIPROC))
663 return parameters->target().should_include_section(sh_type);
664
665 switch (sh_type)
666 {
667 case elfcpp::SHT_NULL:
668 case elfcpp::SHT_SYMTAB:
669 case elfcpp::SHT_DYNSYM:
670 case elfcpp::SHT_HASH:
671 case elfcpp::SHT_DYNAMIC:
672 case elfcpp::SHT_SYMTAB_SHNDX:
673 return false;
674
675 case elfcpp::SHT_STRTAB:
676 // Discard the sections which have special meanings in the ELF
677 // ABI. Keep others (e.g., .stabstr). We could also do this by
678 // checking the sh_link fields of the appropriate sections.
679 return (strcmp(name, ".dynstr") != 0
680 && strcmp(name, ".strtab") != 0
681 && strcmp(name, ".shstrtab") != 0);
682
683 case elfcpp::SHT_RELA:
684 case elfcpp::SHT_REL:
685 case elfcpp::SHT_GROUP:
686 // If we are emitting relocations these should be handled
687 // elsewhere.
688 gold_assert(!parameters->options().relocatable());
689 return false;
690
691 case elfcpp::SHT_PROGBITS:
692 if (parameters->options().strip_debug()
693 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
694 {
695 if (is_debug_info_section(name))
696 return false;
697 }
698 if (parameters->options().strip_debug_non_line()
699 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
700 {
701 // Debugging sections can only be recognized by name.
702 if (is_prefix_of(".debug_", name)
703 && !is_lines_only_debug_section(name + 7))
704 return false;
705 if (is_prefix_of(".zdebug_", name)
706 && !is_lines_only_debug_section(name + 8))
707 return false;
708 }
709 if (parameters->options().strip_debug_gdb()
710 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
711 {
712 // Debugging sections can only be recognized by name.
713 if (is_prefix_of(".debug_", name)
714 && !is_gdb_debug_section(name + 7))
715 return false;
716 if (is_prefix_of(".zdebug_", name)
717 && !is_gdb_debug_section(name + 8))
718 return false;
719 }
720 if (parameters->options().gdb_index()
721 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
722 {
723 // When building .gdb_index, we can strip .debug_pubnames,
724 // .debug_pubtypes, and .debug_aranges sections.
725 if (is_prefix_of(".debug_", name)
726 && is_gdb_fast_lookup_section(name + 7))
727 return false;
728 if (is_prefix_of(".zdebug_", name)
729 && is_gdb_fast_lookup_section(name + 8))
730 return false;
731 }
732 if (parameters->options().strip_lto_sections()
733 && !parameters->options().relocatable()
734 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
735 {
736 // Ignore LTO sections containing intermediate code.
737 if (is_prefix_of(".gnu.lto_", name))
738 return false;
739 }
740 // The GNU linker strips .gnu_debuglink sections, so we do too.
741 // This is a feature used to keep debugging information in
742 // separate files.
743 if (strcmp(name, ".gnu_debuglink") == 0)
744 return false;
745 return true;
746
747 default:
748 return true;
749 }
750 }
751
752 // Return an output section named NAME, or NULL if there is none.
753
754 Output_section*
find_output_section(const char * name) const755 Layout::find_output_section(const char* name) const
756 {
757 for (Section_list::const_iterator p = this->section_list_.begin();
758 p != this->section_list_.end();
759 ++p)
760 if (strcmp((*p)->name(), name) == 0)
761 return *p;
762 return NULL;
763 }
764
765 // Return an output segment of type TYPE, with segment flags SET set
766 // and segment flags CLEAR clear. Return NULL if there is none.
767
768 Output_segment*
find_output_segment(elfcpp::PT type,elfcpp::Elf_Word set,elfcpp::Elf_Word clear) const769 Layout::find_output_segment(elfcpp::PT type, elfcpp::Elf_Word set,
770 elfcpp::Elf_Word clear) const
771 {
772 for (Segment_list::const_iterator p = this->segment_list_.begin();
773 p != this->segment_list_.end();
774 ++p)
775 if (static_cast<elfcpp::PT>((*p)->type()) == type
776 && ((*p)->flags() & set) == set
777 && ((*p)->flags() & clear) == 0)
778 return *p;
779 return NULL;
780 }
781
782 // When we put a .ctors or .dtors section with more than one word into
783 // a .init_array or .fini_array section, we need to reverse the words
784 // in the .ctors/.dtors section. This is because .init_array executes
785 // constructors front to back, where .ctors executes them back to
786 // front, and vice-versa for .fini_array/.dtors. Although we do want
787 // to remap .ctors/.dtors into .init_array/.fini_array because it can
788 // be more efficient, we don't want to change the order in which
789 // constructors/destructors are run. This set just keeps track of
790 // these sections which need to be reversed. It is only changed by
791 // Layout::layout. It should be a private member of Layout, but that
792 // would require layout.h to #include object.h to get the definition
793 // of Section_id.
794 static Unordered_set<Section_id, Section_id_hash> ctors_sections_in_init_array;
795
796 // Return whether OBJECT/SHNDX is a .ctors/.dtors section mapped to a
797 // .init_array/.fini_array section.
798
799 bool
is_ctors_in_init_array(Relobj * relobj,unsigned int shndx) const800 Layout::is_ctors_in_init_array(Relobj* relobj, unsigned int shndx) const
801 {
802 return (ctors_sections_in_init_array.find(Section_id(relobj, shndx))
803 != ctors_sections_in_init_array.end());
804 }
805
806 // Return the output section to use for section NAME with type TYPE
807 // and section flags FLAGS. NAME must be canonicalized in the string
808 // pool, and NAME_KEY is the key. ORDER is where this should appear
809 // in the output sections. IS_RELRO is true for a relro section.
810
811 Output_section*
get_output_section(const char * name,Stringpool::Key name_key,elfcpp::Elf_Word type,elfcpp::Elf_Xword flags,Output_section_order order,bool is_relro)812 Layout::get_output_section(const char* name, Stringpool::Key name_key,
813 elfcpp::Elf_Word type, elfcpp::Elf_Xword flags,
814 Output_section_order order, bool is_relro)
815 {
816 elfcpp::Elf_Word lookup_type = type;
817
818 // For lookup purposes, treat INIT_ARRAY, FINI_ARRAY, and
819 // PREINIT_ARRAY like PROGBITS. This ensures that we combine
820 // .init_array, .fini_array, and .preinit_array sections by name
821 // whatever their type in the input file. We do this because the
822 // types are not always right in the input files.
823 if (lookup_type == elfcpp::SHT_INIT_ARRAY
824 || lookup_type == elfcpp::SHT_FINI_ARRAY
825 || lookup_type == elfcpp::SHT_PREINIT_ARRAY)
826 lookup_type = elfcpp::SHT_PROGBITS;
827
828 elfcpp::Elf_Xword lookup_flags = flags;
829
830 // Ignoring SHF_WRITE and SHF_EXECINSTR here means that we combine
831 // read-write with read-only sections. Some other ELF linkers do
832 // not do this. FIXME: Perhaps there should be an option
833 // controlling this.
834 lookup_flags &= ~(elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR);
835
836 const Key key(name_key, std::make_pair(lookup_type, lookup_flags));
837 const std::pair<Key, Output_section*> v(key, NULL);
838 std::pair<Section_name_map::iterator, bool> ins(
839 this->section_name_map_.insert(v));
840
841 if (!ins.second)
842 return ins.first->second;
843 else
844 {
845 // This is the first time we've seen this name/type/flags
846 // combination. For compatibility with the GNU linker, we
847 // combine sections with contents and zero flags with sections
848 // with non-zero flags. This is a workaround for cases where
849 // assembler code forgets to set section flags. FIXME: Perhaps
850 // there should be an option to control this.
851 Output_section* os = NULL;
852
853 if (lookup_type == elfcpp::SHT_PROGBITS)
854 {
855 if (flags == 0)
856 {
857 Output_section* same_name = this->find_output_section(name);
858 if (same_name != NULL
859 && (same_name->type() == elfcpp::SHT_PROGBITS
860 || same_name->type() == elfcpp::SHT_INIT_ARRAY
861 || same_name->type() == elfcpp::SHT_FINI_ARRAY
862 || same_name->type() == elfcpp::SHT_PREINIT_ARRAY)
863 && (same_name->flags() & elfcpp::SHF_TLS) == 0)
864 os = same_name;
865 }
866 else if ((flags & elfcpp::SHF_TLS) == 0)
867 {
868 elfcpp::Elf_Xword zero_flags = 0;
869 const Key zero_key(name_key, std::make_pair(lookup_type,
870 zero_flags));
871 Section_name_map::iterator p =
872 this->section_name_map_.find(zero_key);
873 if (p != this->section_name_map_.end())
874 os = p->second;
875 }
876 }
877
878 if (os == NULL)
879 os = this->make_output_section(name, type, flags, order, is_relro);
880
881 ins.first->second = os;
882 return os;
883 }
884 }
885
886 // Returns TRUE iff NAME (an input section from RELOBJ) will
887 // be mapped to an output section that should be KEPT.
888
889 bool
keep_input_section(const Relobj * relobj,const char * name)890 Layout::keep_input_section(const Relobj* relobj, const char* name)
891 {
892 if (! this->script_options_->saw_sections_clause())
893 return false;
894
895 Script_sections* ss = this->script_options_->script_sections();
896 const char* file_name = relobj == NULL ? NULL : relobj->name().c_str();
897 Output_section** output_section_slot;
898 Script_sections::Section_type script_section_type;
899 bool keep;
900
901 name = ss->output_section_name(file_name, name, &output_section_slot,
902 &script_section_type, &keep);
903 return name != NULL && keep;
904 }
905
906 // Clear the input section flags that should not be copied to the
907 // output section.
908
909 elfcpp::Elf_Xword
get_output_section_flags(elfcpp::Elf_Xword input_section_flags)910 Layout::get_output_section_flags(elfcpp::Elf_Xword input_section_flags)
911 {
912 // Some flags in the input section should not be automatically
913 // copied to the output section.
914 input_section_flags &= ~ (elfcpp::SHF_INFO_LINK
915 | elfcpp::SHF_GROUP
916 | elfcpp::SHF_COMPRESSED
917 | elfcpp::SHF_MERGE
918 | elfcpp::SHF_STRINGS);
919
920 // We only clear the SHF_LINK_ORDER flag in for
921 // a non-relocatable link.
922 if (!parameters->options().relocatable())
923 input_section_flags &= ~elfcpp::SHF_LINK_ORDER;
924
925 return input_section_flags;
926 }
927
928 // Pick the output section to use for section NAME, in input file
929 // RELOBJ, with type TYPE and flags FLAGS. RELOBJ may be NULL for a
930 // linker created section. IS_INPUT_SECTION is true if we are
931 // choosing an output section for an input section found in a input
932 // file. ORDER is where this section should appear in the output
933 // sections. IS_RELRO is true for a relro section. This will return
934 // NULL if the input section should be discarded.
935
936 Output_section*
choose_output_section(const Relobj * relobj,const char * name,elfcpp::Elf_Word type,elfcpp::Elf_Xword flags,bool is_input_section,Output_section_order order,bool is_relro)937 Layout::choose_output_section(const Relobj* relobj, const char* name,
938 elfcpp::Elf_Word type, elfcpp::Elf_Xword flags,
939 bool is_input_section, Output_section_order order,
940 bool is_relro)
941 {
942 // We should not see any input sections after we have attached
943 // sections to segments.
944 gold_assert(!is_input_section || !this->sections_are_attached_);
945
946 flags = this->get_output_section_flags(flags);
947
948 if (this->script_options_->saw_sections_clause())
949 {
950 // We are using a SECTIONS clause, so the output section is
951 // chosen based only on the name.
952
953 Script_sections* ss = this->script_options_->script_sections();
954 const char* file_name = relobj == NULL ? NULL : relobj->name().c_str();
955 Output_section** output_section_slot;
956 Script_sections::Section_type script_section_type;
957 const char* orig_name = name;
958 bool keep;
959 name = ss->output_section_name(file_name, name, &output_section_slot,
960 &script_section_type, &keep);
961
962 if (name == NULL)
963 {
964 gold_debug(DEBUG_SCRIPT, _("Unable to create output section '%s' "
965 "because it is not allowed by the "
966 "SECTIONS clause of the linker script"),
967 orig_name);
968 // The SECTIONS clause says to discard this input section.
969 return NULL;
970 }
971
972 // We can only handle script section types ST_NONE and ST_NOLOAD.
973 switch (script_section_type)
974 {
975 case Script_sections::ST_NONE:
976 break;
977 case Script_sections::ST_NOLOAD:
978 flags &= elfcpp::SHF_ALLOC;
979 break;
980 default:
981 gold_unreachable();
982 }
983
984 // If this is an orphan section--one not mentioned in the linker
985 // script--then OUTPUT_SECTION_SLOT will be NULL, and we do the
986 // default processing below.
987
988 if (output_section_slot != NULL)
989 {
990 if (*output_section_slot != NULL)
991 {
992 (*output_section_slot)->update_flags_for_input_section(flags);
993 return *output_section_slot;
994 }
995
996 // We don't put sections found in the linker script into
997 // SECTION_NAME_MAP_. That keeps us from getting confused
998 // if an orphan section is mapped to a section with the same
999 // name as one in the linker script.
1000
1001 name = this->namepool_.add(name, false, NULL);
1002
1003 Output_section* os = this->make_output_section(name, type, flags,
1004 order, is_relro);
1005
1006 os->set_found_in_sections_clause();
1007
1008 // Special handling for NOLOAD sections.
1009 if (script_section_type == Script_sections::ST_NOLOAD)
1010 {
1011 os->set_is_noload();
1012
1013 // The constructor of Output_section sets addresses of non-ALLOC
1014 // sections to 0 by default. We don't want that for NOLOAD
1015 // sections even if they have no SHF_ALLOC flag.
1016 if ((os->flags() & elfcpp::SHF_ALLOC) == 0
1017 && os->is_address_valid())
1018 {
1019 gold_assert(os->address() == 0
1020 && !os->is_offset_valid()
1021 && !os->is_data_size_valid());
1022 os->reset_address_and_file_offset();
1023 }
1024 }
1025
1026 *output_section_slot = os;
1027 return os;
1028 }
1029 }
1030
1031 // FIXME: Handle SHF_OS_NONCONFORMING somewhere.
1032
1033 size_t len = strlen(name);
1034 std::string uncompressed_name;
1035
1036 // Compressed debug sections should be mapped to the corresponding
1037 // uncompressed section.
1038 if (is_compressed_debug_section(name))
1039 {
1040 uncompressed_name =
1041 corresponding_uncompressed_section_name(std::string(name, len));
1042 name = uncompressed_name.c_str();
1043 len = uncompressed_name.length();
1044 }
1045
1046 // Turn NAME from the name of the input section into the name of the
1047 // output section.
1048 if (is_input_section
1049 && !this->script_options_->saw_sections_clause()
1050 && !parameters->options().relocatable())
1051 {
1052 const char *orig_name = name;
1053 name = parameters->target().output_section_name(relobj, name, &len);
1054 if (name == NULL)
1055 name = Layout::output_section_name(relobj, orig_name, &len);
1056 }
1057
1058 Stringpool::Key name_key;
1059 name = this->namepool_.add_with_length(name, len, true, &name_key);
1060
1061 // Find or make the output section. The output section is selected
1062 // based on the section name, type, and flags.
1063 return this->get_output_section(name, name_key, type, flags, order, is_relro);
1064 }
1065
1066 // For incremental links, record the initial fixed layout of a section
1067 // from the base file, and return a pointer to the Output_section.
1068
1069 template<int size, bool big_endian>
1070 Output_section*
init_fixed_output_section(const char * name,elfcpp::Shdr<size,big_endian> & shdr)1071 Layout::init_fixed_output_section(const char* name,
1072 elfcpp::Shdr<size, big_endian>& shdr)
1073 {
1074 unsigned int sh_type = shdr.get_sh_type();
1075
1076 // We preserve the layout of PROGBITS, NOBITS, INIT_ARRAY, FINI_ARRAY,
1077 // PRE_INIT_ARRAY, and NOTE sections.
1078 // All others will be created from scratch and reallocated.
1079 if (!can_incremental_update(sh_type))
1080 return NULL;
1081
1082 // If we're generating a .gdb_index section, we need to regenerate
1083 // it from scratch.
1084 if (parameters->options().gdb_index()
1085 && sh_type == elfcpp::SHT_PROGBITS
1086 && strcmp(name, ".gdb_index") == 0)
1087 return NULL;
1088
1089 typename elfcpp::Elf_types<size>::Elf_Addr sh_addr = shdr.get_sh_addr();
1090 typename elfcpp::Elf_types<size>::Elf_Off sh_offset = shdr.get_sh_offset();
1091 typename elfcpp::Elf_types<size>::Elf_WXword sh_size = shdr.get_sh_size();
1092 typename elfcpp::Elf_types<size>::Elf_WXword sh_flags = shdr.get_sh_flags();
1093 typename elfcpp::Elf_types<size>::Elf_WXword sh_addralign =
1094 shdr.get_sh_addralign();
1095
1096 // Make the output section.
1097 Stringpool::Key name_key;
1098 name = this->namepool_.add(name, true, &name_key);
1099 Output_section* os = this->get_output_section(name, name_key, sh_type,
1100 sh_flags, ORDER_INVALID, false);
1101 os->set_fixed_layout(sh_addr, sh_offset, sh_size, sh_addralign);
1102 if (sh_type != elfcpp::SHT_NOBITS)
1103 this->free_list_.remove(sh_offset, sh_offset + sh_size);
1104 return os;
1105 }
1106
1107 // Return the index by which an input section should be ordered. This
1108 // is used to sort some .text sections, for compatibility with GNU ld.
1109
1110 int
special_ordering_of_input_section(const char * name)1111 Layout::special_ordering_of_input_section(const char* name)
1112 {
1113 // The GNU linker has some special handling for some sections that
1114 // wind up in the .text section. Sections that start with these
1115 // prefixes must appear first, and must appear in the order listed
1116 // here.
1117 static const char* const text_section_sort[] =
1118 {
1119 ".text.unlikely",
1120 ".text.exit",
1121 ".text.startup",
1122 ".text.hot"
1123 };
1124
1125 for (size_t i = 0;
1126 i < sizeof(text_section_sort) / sizeof(text_section_sort[0]);
1127 i++)
1128 if (is_prefix_of(text_section_sort[i], name))
1129 return i;
1130
1131 return -1;
1132 }
1133
1134 // Return the output section to use for input section SHNDX, with name
1135 // NAME, with header HEADER, from object OBJECT. RELOC_SHNDX is the
1136 // index of a relocation section which applies to this section, or 0
1137 // if none, or -1U if more than one. RELOC_TYPE is the type of the
1138 // relocation section if there is one. Set *OFF to the offset of this
1139 // input section without the output section. Return NULL if the
1140 // section should be discarded. Set *OFF to -1 if the section
1141 // contents should not be written directly to the output file, but
1142 // will instead receive special handling.
1143
1144 template<int size, bool big_endian>
1145 Output_section*
layout(Sized_relobj_file<size,big_endian> * object,unsigned int shndx,const char * name,const elfcpp::Shdr<size,big_endian> & shdr,unsigned int reloc_shndx,unsigned int,off_t * off)1146 Layout::layout(Sized_relobj_file<size, big_endian>* object, unsigned int shndx,
1147 const char* name, const elfcpp::Shdr<size, big_endian>& shdr,
1148 unsigned int reloc_shndx, unsigned int, off_t* off)
1149 {
1150 *off = 0;
1151
1152 if (!this->include_section(object, name, shdr))
1153 return NULL;
1154
1155 elfcpp::Elf_Word sh_type = shdr.get_sh_type();
1156
1157 // In a relocatable link a grouped section must not be combined with
1158 // any other sections.
1159 Output_section* os;
1160 if (parameters->options().relocatable()
1161 && (shdr.get_sh_flags() & elfcpp::SHF_GROUP) != 0)
1162 {
1163 // Some flags in the input section should not be automatically
1164 // copied to the output section.
1165 elfcpp::Elf_Xword flags = (shdr.get_sh_flags()
1166 & ~ elfcpp::SHF_COMPRESSED);
1167 name = this->namepool_.add(name, true, NULL);
1168 os = this->make_output_section(name, sh_type, flags,
1169 ORDER_INVALID, false);
1170 }
1171 else
1172 {
1173 // Plugins can choose to place one or more subsets of sections in
1174 // unique segments and this is done by mapping these section subsets
1175 // to unique output sections. Check if this section needs to be
1176 // remapped to a unique output section.
1177 Section_segment_map::iterator it
1178 = this->section_segment_map_.find(Const_section_id(object, shndx));
1179 if (it == this->section_segment_map_.end())
1180 {
1181 os = this->choose_output_section(object, name, sh_type,
1182 shdr.get_sh_flags(), true,
1183 ORDER_INVALID, false);
1184 }
1185 else
1186 {
1187 // We know the name of the output section, directly call
1188 // get_output_section here by-passing choose_output_section.
1189 elfcpp::Elf_Xword flags
1190 = this->get_output_section_flags(shdr.get_sh_flags());
1191
1192 const char* os_name = it->second->name;
1193 Stringpool::Key name_key;
1194 os_name = this->namepool_.add(os_name, true, &name_key);
1195 os = this->get_output_section(os_name, name_key, sh_type, flags,
1196 ORDER_INVALID, false);
1197 if (!os->is_unique_segment())
1198 {
1199 os->set_is_unique_segment();
1200 os->set_extra_segment_flags(it->second->flags);
1201 os->set_segment_alignment(it->second->align);
1202 }
1203 }
1204 if (os == NULL)
1205 return NULL;
1206 }
1207
1208 // By default the GNU linker sorts input sections whose names match
1209 // .ctors.*, .dtors.*, .init_array.*, or .fini_array.*. The
1210 // sections are sorted by name. This is used to implement
1211 // constructor priority ordering. We are compatible. When we put
1212 // .ctor sections in .init_array and .dtor sections in .fini_array,
1213 // we must also sort plain .ctor and .dtor sections.
1214 if (!this->script_options_->saw_sections_clause()
1215 && !parameters->options().relocatable()
1216 && (is_prefix_of(".ctors.", name)
1217 || is_prefix_of(".dtors.", name)
1218 || is_prefix_of(".init_array.", name)
1219 || is_prefix_of(".fini_array.", name)
1220 || (parameters->options().ctors_in_init_array()
1221 && (strcmp(name, ".ctors") == 0
1222 || strcmp(name, ".dtors") == 0))))
1223 os->set_must_sort_attached_input_sections();
1224
1225 // By default the GNU linker sorts some special text sections ahead
1226 // of others. We are compatible.
1227 if (parameters->options().text_reorder()
1228 && !this->script_options_->saw_sections_clause()
1229 && !this->is_section_ordering_specified()
1230 && !parameters->options().relocatable()
1231 && Layout::special_ordering_of_input_section(name) >= 0)
1232 os->set_must_sort_attached_input_sections();
1233
1234 // If this is a .ctors or .ctors.* section being mapped to a
1235 // .init_array section, or a .dtors or .dtors.* section being mapped
1236 // to a .fini_array section, we will need to reverse the words if
1237 // there is more than one. Record this section for later. See
1238 // ctors_sections_in_init_array above.
1239 if (!this->script_options_->saw_sections_clause()
1240 && !parameters->options().relocatable()
1241 && shdr.get_sh_size() > size / 8
1242 && (((strcmp(name, ".ctors") == 0
1243 || is_prefix_of(".ctors.", name))
1244 && strcmp(os->name(), ".init_array") == 0)
1245 || ((strcmp(name, ".dtors") == 0
1246 || is_prefix_of(".dtors.", name))
1247 && strcmp(os->name(), ".fini_array") == 0)))
1248 ctors_sections_in_init_array.insert(Section_id(object, shndx));
1249
1250 // FIXME: Handle SHF_LINK_ORDER somewhere.
1251
1252 elfcpp::Elf_Xword orig_flags = os->flags();
1253
1254 *off = os->add_input_section(this, object, shndx, name, shdr, reloc_shndx,
1255 this->script_options_->saw_sections_clause());
1256
1257 // If the flags changed, we may have to change the order.
1258 if ((orig_flags & elfcpp::SHF_ALLOC) != 0)
1259 {
1260 orig_flags &= (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR);
1261 elfcpp::Elf_Xword new_flags =
1262 os->flags() & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR);
1263 if (orig_flags != new_flags)
1264 os->set_order(this->default_section_order(os, false));
1265 }
1266
1267 this->have_added_input_section_ = true;
1268
1269 return os;
1270 }
1271
1272 // Maps section SECN to SEGMENT s.
1273 void
insert_section_segment_map(Const_section_id secn,Unique_segment_info * s)1274 Layout::insert_section_segment_map(Const_section_id secn,
1275 Unique_segment_info *s)
1276 {
1277 gold_assert(this->unique_segment_for_sections_specified_);
1278 this->section_segment_map_[secn] = s;
1279 }
1280
1281 // Handle a relocation section when doing a relocatable link.
1282
1283 template<int size, bool big_endian>
1284 Output_section*
layout_reloc(Sized_relobj_file<size,big_endian> * object,unsigned int,const elfcpp::Shdr<size,big_endian> & shdr,Output_section * data_section,Relocatable_relocs * rr)1285 Layout::layout_reloc(Sized_relobj_file<size, big_endian>* object,
1286 unsigned int,
1287 const elfcpp::Shdr<size, big_endian>& shdr,
1288 Output_section* data_section,
1289 Relocatable_relocs* rr)
1290 {
1291 gold_assert(parameters->options().relocatable()
1292 || parameters->options().emit_relocs());
1293
1294 int sh_type = shdr.get_sh_type();
1295
1296 std::string name;
1297 if (sh_type == elfcpp::SHT_REL)
1298 name = ".rel";
1299 else if (sh_type == elfcpp::SHT_RELA)
1300 name = ".rela";
1301 else
1302 gold_unreachable();
1303 name += data_section->name();
1304
1305 // In a relocatable link relocs for a grouped section must not be
1306 // combined with other reloc sections.
1307 Output_section* os;
1308 if (!parameters->options().relocatable()
1309 || (data_section->flags() & elfcpp::SHF_GROUP) == 0)
1310 os = this->choose_output_section(object, name.c_str(), sh_type,
1311 shdr.get_sh_flags(), false,
1312 ORDER_INVALID, false);
1313 else
1314 {
1315 const char* n = this->namepool_.add(name.c_str(), true, NULL);
1316 os = this->make_output_section(n, sh_type, shdr.get_sh_flags(),
1317 ORDER_INVALID, false);
1318 }
1319
1320 os->set_should_link_to_symtab();
1321 os->set_info_section(data_section);
1322
1323 Output_section_data* posd;
1324 if (sh_type == elfcpp::SHT_REL)
1325 {
1326 os->set_entsize(elfcpp::Elf_sizes<size>::rel_size);
1327 posd = new Output_relocatable_relocs<elfcpp::SHT_REL,
1328 size,
1329 big_endian>(rr);
1330 }
1331 else if (sh_type == elfcpp::SHT_RELA)
1332 {
1333 os->set_entsize(elfcpp::Elf_sizes<size>::rela_size);
1334 posd = new Output_relocatable_relocs<elfcpp::SHT_RELA,
1335 size,
1336 big_endian>(rr);
1337 }
1338 else
1339 gold_unreachable();
1340
1341 os->add_output_section_data(posd);
1342 rr->set_output_data(posd);
1343
1344 return os;
1345 }
1346
1347 // Handle a group section when doing a relocatable link.
1348
1349 template<int size, bool big_endian>
1350 void
layout_group(Symbol_table * symtab,Sized_relobj_file<size,big_endian> * object,unsigned int,const char * group_section_name,const char * signature,const elfcpp::Shdr<size,big_endian> & shdr,elfcpp::Elf_Word flags,std::vector<unsigned int> * shndxes)1351 Layout::layout_group(Symbol_table* symtab,
1352 Sized_relobj_file<size, big_endian>* object,
1353 unsigned int,
1354 const char* group_section_name,
1355 const char* signature,
1356 const elfcpp::Shdr<size, big_endian>& shdr,
1357 elfcpp::Elf_Word flags,
1358 std::vector<unsigned int>* shndxes)
1359 {
1360 gold_assert(parameters->options().relocatable());
1361 gold_assert(shdr.get_sh_type() == elfcpp::SHT_GROUP);
1362 group_section_name = this->namepool_.add(group_section_name, true, NULL);
1363 Output_section* os = this->make_output_section(group_section_name,
1364 elfcpp::SHT_GROUP,
1365 shdr.get_sh_flags(),
1366 ORDER_INVALID, false);
1367
1368 // We need to find a symbol with the signature in the symbol table.
1369 // If we don't find one now, we need to look again later.
1370 Symbol* sym = symtab->lookup(signature, NULL);
1371 if (sym != NULL)
1372 os->set_info_symndx(sym);
1373 else
1374 {
1375 // Reserve some space to minimize reallocations.
1376 if (this->group_signatures_.empty())
1377 this->group_signatures_.reserve(this->number_of_input_files_ * 16);
1378
1379 // We will wind up using a symbol whose name is the signature.
1380 // So just put the signature in the symbol name pool to save it.
1381 signature = symtab->canonicalize_name(signature);
1382 this->group_signatures_.push_back(Group_signature(os, signature));
1383 }
1384
1385 os->set_should_link_to_symtab();
1386 os->set_entsize(4);
1387
1388 section_size_type entry_count =
1389 convert_to_section_size_type(shdr.get_sh_size() / 4);
1390 Output_section_data* posd =
1391 new Output_data_group<size, big_endian>(object, entry_count, flags,
1392 shndxes);
1393 os->add_output_section_data(posd);
1394 }
1395
1396 // Special GNU handling of sections name .eh_frame. They will
1397 // normally hold exception frame data as defined by the C++ ABI
1398 // (http://codesourcery.com/cxx-abi/).
1399
1400 template<int size, bool big_endian>
1401 Output_section*
layout_eh_frame(Sized_relobj_file<size,big_endian> * object,const unsigned char * symbols,off_t symbols_size,const unsigned char * symbol_names,off_t symbol_names_size,unsigned int shndx,const elfcpp::Shdr<size,big_endian> & shdr,unsigned int reloc_shndx,unsigned int reloc_type,off_t * off)1402 Layout::layout_eh_frame(Sized_relobj_file<size, big_endian>* object,
1403 const unsigned char* symbols,
1404 off_t symbols_size,
1405 const unsigned char* symbol_names,
1406 off_t symbol_names_size,
1407 unsigned int shndx,
1408 const elfcpp::Shdr<size, big_endian>& shdr,
1409 unsigned int reloc_shndx, unsigned int reloc_type,
1410 off_t* off)
1411 {
1412 gold_assert(shdr.get_sh_type() == elfcpp::SHT_PROGBITS
1413 || shdr.get_sh_type() == elfcpp::SHT_X86_64_UNWIND);
1414 gold_assert((shdr.get_sh_flags() & elfcpp::SHF_ALLOC) != 0);
1415
1416 Output_section* os = this->make_eh_frame_section(object);
1417 if (os == NULL)
1418 return NULL;
1419
1420 gold_assert(this->eh_frame_section_ == os);
1421
1422 elfcpp::Elf_Xword orig_flags = os->flags();
1423
1424 Eh_frame::Eh_frame_section_disposition disp =
1425 Eh_frame::EH_UNRECOGNIZED_SECTION;
1426 if (!parameters->incremental())
1427 {
1428 disp = this->eh_frame_data_->add_ehframe_input_section(object,
1429 symbols,
1430 symbols_size,
1431 symbol_names,
1432 symbol_names_size,
1433 shndx,
1434 reloc_shndx,
1435 reloc_type);
1436 }
1437
1438 if (disp == Eh_frame::EH_OPTIMIZABLE_SECTION)
1439 {
1440 os->update_flags_for_input_section(shdr.get_sh_flags());
1441
1442 // A writable .eh_frame section is a RELRO section.
1443 if ((orig_flags & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR))
1444 != (os->flags() & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR)))
1445 {
1446 os->set_is_relro();
1447 os->set_order(ORDER_RELRO);
1448 }
1449
1450 *off = -1;
1451 return os;
1452 }
1453
1454 if (disp == Eh_frame::EH_END_MARKER_SECTION && !this->added_eh_frame_data_)
1455 {
1456 // We found the end marker section, so now we can add the set of
1457 // optimized sections to the output section. We need to postpone
1458 // adding this until we've found a section we can optimize so that
1459 // the .eh_frame section in crtbeginT.o winds up at the start of
1460 // the output section.
1461 os->add_output_section_data(this->eh_frame_data_);
1462 this->added_eh_frame_data_ = true;
1463 }
1464
1465 // We couldn't handle this .eh_frame section for some reason.
1466 // Add it as a normal section.
1467 bool saw_sections_clause = this->script_options_->saw_sections_clause();
1468 *off = os->add_input_section(this, object, shndx, ".eh_frame", shdr,
1469 reloc_shndx, saw_sections_clause);
1470 this->have_added_input_section_ = true;
1471
1472 if ((orig_flags & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR))
1473 != (os->flags() & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR)))
1474 os->set_order(this->default_section_order(os, false));
1475
1476 return os;
1477 }
1478
1479 void
finalize_eh_frame_section()1480 Layout::finalize_eh_frame_section()
1481 {
1482 // If we never found an end marker section, we need to add the
1483 // optimized eh sections to the output section now.
1484 if (!parameters->incremental()
1485 && this->eh_frame_section_ != NULL
1486 && !this->added_eh_frame_data_)
1487 {
1488 this->eh_frame_section_->add_output_section_data(this->eh_frame_data_);
1489 this->added_eh_frame_data_ = true;
1490 }
1491 }
1492
1493 // Create and return the magic .eh_frame section. Create
1494 // .eh_frame_hdr also if appropriate. OBJECT is the object with the
1495 // input .eh_frame section; it may be NULL.
1496
1497 Output_section*
make_eh_frame_section(const Relobj * object)1498 Layout::make_eh_frame_section(const Relobj* object)
1499 {
1500 // FIXME: On x86_64, this could use SHT_X86_64_UNWIND rather than
1501 // SHT_PROGBITS.
1502 Output_section* os = this->choose_output_section(object, ".eh_frame",
1503 elfcpp::SHT_PROGBITS,
1504 elfcpp::SHF_ALLOC, false,
1505 ORDER_EHFRAME, false);
1506 if (os == NULL)
1507 return NULL;
1508
1509 if (this->eh_frame_section_ == NULL)
1510 {
1511 this->eh_frame_section_ = os;
1512 this->eh_frame_data_ = new Eh_frame();
1513
1514 // For incremental linking, we do not optimize .eh_frame sections
1515 // or create a .eh_frame_hdr section.
1516 if (parameters->options().eh_frame_hdr() && !parameters->incremental())
1517 {
1518 Output_section* hdr_os =
1519 this->choose_output_section(NULL, ".eh_frame_hdr",
1520 elfcpp::SHT_PROGBITS,
1521 elfcpp::SHF_ALLOC, false,
1522 ORDER_EHFRAME, false);
1523
1524 if (hdr_os != NULL)
1525 {
1526 Eh_frame_hdr* hdr_posd = new Eh_frame_hdr(os,
1527 this->eh_frame_data_);
1528 hdr_os->add_output_section_data(hdr_posd);
1529
1530 hdr_os->set_after_input_sections();
1531
1532 if (!this->script_options_->saw_phdrs_clause())
1533 {
1534 Output_segment* hdr_oseg;
1535 hdr_oseg = this->make_output_segment(elfcpp::PT_GNU_EH_FRAME,
1536 elfcpp::PF_R);
1537 hdr_oseg->add_output_section_to_nonload(hdr_os,
1538 elfcpp::PF_R);
1539 }
1540
1541 this->eh_frame_data_->set_eh_frame_hdr(hdr_posd);
1542 }
1543 }
1544 }
1545
1546 return os;
1547 }
1548
1549 // Add an exception frame for a PLT. This is called from target code.
1550
1551 void
add_eh_frame_for_plt(Output_data * plt,const unsigned char * cie_data,size_t cie_length,const unsigned char * fde_data,size_t fde_length)1552 Layout::add_eh_frame_for_plt(Output_data* plt, const unsigned char* cie_data,
1553 size_t cie_length, const unsigned char* fde_data,
1554 size_t fde_length)
1555 {
1556 if (parameters->incremental())
1557 {
1558 // FIXME: Maybe this could work some day....
1559 return;
1560 }
1561 Output_section* os = this->make_eh_frame_section(NULL);
1562 if (os == NULL)
1563 return;
1564 this->eh_frame_data_->add_ehframe_for_plt(plt, cie_data, cie_length,
1565 fde_data, fde_length);
1566 if (!this->added_eh_frame_data_)
1567 {
1568 os->add_output_section_data(this->eh_frame_data_);
1569 this->added_eh_frame_data_ = true;
1570 }
1571 }
1572
1573 // Scan a .debug_info or .debug_types section, and add summary
1574 // information to the .gdb_index section.
1575
1576 template<int size, bool big_endian>
1577 void
add_to_gdb_index(bool is_type_unit,Sized_relobj<size,big_endian> * object,const unsigned char * symbols,off_t symbols_size,unsigned int shndx,unsigned int reloc_shndx,unsigned int reloc_type)1578 Layout::add_to_gdb_index(bool is_type_unit,
1579 Sized_relobj<size, big_endian>* object,
1580 const unsigned char* symbols,
1581 off_t symbols_size,
1582 unsigned int shndx,
1583 unsigned int reloc_shndx,
1584 unsigned int reloc_type)
1585 {
1586 if (this->gdb_index_data_ == NULL)
1587 {
1588 Output_section* os = this->choose_output_section(NULL, ".gdb_index",
1589 elfcpp::SHT_PROGBITS, 0,
1590 false, ORDER_INVALID,
1591 false);
1592 if (os == NULL)
1593 return;
1594
1595 this->gdb_index_data_ = new Gdb_index(os);
1596 os->add_output_section_data(this->gdb_index_data_);
1597 os->set_after_input_sections();
1598 }
1599
1600 this->gdb_index_data_->scan_debug_info(is_type_unit, object, symbols,
1601 symbols_size, shndx, reloc_shndx,
1602 reloc_type);
1603 }
1604
1605 // Add POSD to an output section using NAME, TYPE, and FLAGS. Return
1606 // the output section.
1607
1608 Output_section*
add_output_section_data(const char * name,elfcpp::Elf_Word type,elfcpp::Elf_Xword flags,Output_section_data * posd,Output_section_order order,bool is_relro)1609 Layout::add_output_section_data(const char* name, elfcpp::Elf_Word type,
1610 elfcpp::Elf_Xword flags,
1611 Output_section_data* posd,
1612 Output_section_order order, bool is_relro)
1613 {
1614 Output_section* os = this->choose_output_section(NULL, name, type, flags,
1615 false, order, is_relro);
1616 if (os != NULL)
1617 os->add_output_section_data(posd);
1618 return os;
1619 }
1620
1621 // Map section flags to segment flags.
1622
1623 elfcpp::Elf_Word
section_flags_to_segment(elfcpp::Elf_Xword flags)1624 Layout::section_flags_to_segment(elfcpp::Elf_Xword flags)
1625 {
1626 elfcpp::Elf_Word ret = elfcpp::PF_R;
1627 if ((flags & elfcpp::SHF_WRITE) != 0)
1628 ret |= elfcpp::PF_W;
1629 if ((flags & elfcpp::SHF_EXECINSTR) != 0)
1630 ret |= elfcpp::PF_X;
1631 return ret;
1632 }
1633
1634 // Make a new Output_section, and attach it to segments as
1635 // appropriate. ORDER is the order in which this section should
1636 // appear in the output segment. IS_RELRO is true if this is a relro
1637 // (read-only after relocations) section.
1638
1639 Output_section*
make_output_section(const char * name,elfcpp::Elf_Word type,elfcpp::Elf_Xword flags,Output_section_order order,bool is_relro)1640 Layout::make_output_section(const char* name, elfcpp::Elf_Word type,
1641 elfcpp::Elf_Xword flags,
1642 Output_section_order order, bool is_relro)
1643 {
1644 Output_section* os;
1645 if ((flags & elfcpp::SHF_ALLOC) == 0
1646 && strcmp(parameters->options().compress_debug_sections(), "none") != 0
1647 && is_compressible_debug_section(name))
1648 os = new Output_compressed_section(¶meters->options(), name, type,
1649 flags);
1650 else if ((flags & elfcpp::SHF_ALLOC) == 0
1651 && parameters->options().strip_debug_non_line()
1652 && strcmp(".debug_abbrev", name) == 0)
1653 {
1654 os = this->debug_abbrev_ = new Output_reduced_debug_abbrev_section(
1655 name, type, flags);
1656 if (this->debug_info_)
1657 this->debug_info_->set_abbreviations(this->debug_abbrev_);
1658 }
1659 else if ((flags & elfcpp::SHF_ALLOC) == 0
1660 && parameters->options().strip_debug_non_line()
1661 && strcmp(".debug_info", name) == 0)
1662 {
1663 os = this->debug_info_ = new Output_reduced_debug_info_section(
1664 name, type, flags);
1665 if (this->debug_abbrev_)
1666 this->debug_info_->set_abbreviations(this->debug_abbrev_);
1667 }
1668 else
1669 {
1670 // Sometimes .init_array*, .preinit_array* and .fini_array* do
1671 // not have correct section types. Force them here.
1672 if (type == elfcpp::SHT_PROGBITS)
1673 {
1674 if (is_prefix_of(".init_array", name))
1675 type = elfcpp::SHT_INIT_ARRAY;
1676 else if (is_prefix_of(".preinit_array", name))
1677 type = elfcpp::SHT_PREINIT_ARRAY;
1678 else if (is_prefix_of(".fini_array", name))
1679 type = elfcpp::SHT_FINI_ARRAY;
1680 }
1681
1682 // FIXME: const_cast is ugly.
1683 Target* target = const_cast<Target*>(¶meters->target());
1684 os = target->make_output_section(name, type, flags);
1685 }
1686
1687 // With -z relro, we have to recognize the special sections by name.
1688 // There is no other way.
1689 bool is_relro_local = false;
1690 if (!this->script_options_->saw_sections_clause()
1691 && parameters->options().relro()
1692 && (flags & elfcpp::SHF_ALLOC) != 0
1693 && (flags & elfcpp::SHF_WRITE) != 0)
1694 {
1695 if (type == elfcpp::SHT_PROGBITS)
1696 {
1697 if ((flags & elfcpp::SHF_TLS) != 0)
1698 is_relro = true;
1699 else if (strcmp(name, ".data.rel.ro") == 0)
1700 is_relro = true;
1701 else if (strcmp(name, ".data.rel.ro.local") == 0)
1702 {
1703 is_relro = true;
1704 is_relro_local = true;
1705 }
1706 else if (strcmp(name, ".ctors") == 0
1707 || strcmp(name, ".dtors") == 0
1708 || strcmp(name, ".jcr") == 0)
1709 is_relro = true;
1710 }
1711 else if (type == elfcpp::SHT_INIT_ARRAY
1712 || type == elfcpp::SHT_FINI_ARRAY
1713 || type == elfcpp::SHT_PREINIT_ARRAY)
1714 is_relro = true;
1715 }
1716
1717 if (is_relro)
1718 os->set_is_relro();
1719
1720 if (order == ORDER_INVALID && (flags & elfcpp::SHF_ALLOC) != 0)
1721 order = this->default_section_order(os, is_relro_local);
1722
1723 os->set_order(order);
1724
1725 parameters->target().new_output_section(os);
1726
1727 this->section_list_.push_back(os);
1728
1729 // The GNU linker by default sorts some sections by priority, so we
1730 // do the same. We need to know that this might happen before we
1731 // attach any input sections.
1732 if (!this->script_options_->saw_sections_clause()
1733 && !parameters->options().relocatable()
1734 && (strcmp(name, ".init_array") == 0
1735 || strcmp(name, ".fini_array") == 0
1736 || (!parameters->options().ctors_in_init_array()
1737 && (strcmp(name, ".ctors") == 0
1738 || strcmp(name, ".dtors") == 0))))
1739 os->set_may_sort_attached_input_sections();
1740
1741 // The GNU linker by default sorts .text.{unlikely,exit,startup,hot}
1742 // sections before other .text sections. We are compatible. We
1743 // need to know that this might happen before we attach any input
1744 // sections.
1745 if (parameters->options().text_reorder()
1746 && !this->script_options_->saw_sections_clause()
1747 && !this->is_section_ordering_specified()
1748 && !parameters->options().relocatable()
1749 && strcmp(name, ".text") == 0)
1750 os->set_may_sort_attached_input_sections();
1751
1752 // GNU linker sorts section by name with --sort-section=name.
1753 if (strcmp(parameters->options().sort_section(), "name") == 0)
1754 os->set_must_sort_attached_input_sections();
1755
1756 // Check for .stab*str sections, as .stab* sections need to link to
1757 // them.
1758 if (type == elfcpp::SHT_STRTAB
1759 && !this->have_stabstr_section_
1760 && strncmp(name, ".stab", 5) == 0
1761 && strcmp(name + strlen(name) - 3, "str") == 0)
1762 this->have_stabstr_section_ = true;
1763
1764 // During a full incremental link, we add patch space to most
1765 // PROGBITS and NOBITS sections. Flag those that may be
1766 // arbitrarily padded.
1767 if ((type == elfcpp::SHT_PROGBITS || type == elfcpp::SHT_NOBITS)
1768 && order != ORDER_INTERP
1769 && order != ORDER_INIT
1770 && order != ORDER_PLT
1771 && order != ORDER_FINI
1772 && order != ORDER_RELRO_LAST
1773 && order != ORDER_NON_RELRO_FIRST
1774 && strcmp(name, ".eh_frame") != 0
1775 && strcmp(name, ".ctors") != 0
1776 && strcmp(name, ".dtors") != 0
1777 && strcmp(name, ".jcr") != 0)
1778 {
1779 os->set_is_patch_space_allowed();
1780
1781 // Certain sections require "holes" to be filled with
1782 // specific fill patterns. These fill patterns may have
1783 // a minimum size, so we must prevent allocations from the
1784 // free list that leave a hole smaller than the minimum.
1785 if (strcmp(name, ".debug_info") == 0)
1786 os->set_free_space_fill(new Output_fill_debug_info(false));
1787 else if (strcmp(name, ".debug_types") == 0)
1788 os->set_free_space_fill(new Output_fill_debug_info(true));
1789 else if (strcmp(name, ".debug_line") == 0)
1790 os->set_free_space_fill(new Output_fill_debug_line());
1791 }
1792
1793 // If we have already attached the sections to segments, then we
1794 // need to attach this one now. This happens for sections created
1795 // directly by the linker.
1796 if (this->sections_are_attached_)
1797 this->attach_section_to_segment(¶meters->target(), os);
1798
1799 return os;
1800 }
1801
1802 // Return the default order in which a section should be placed in an
1803 // output segment. This function captures a lot of the ideas in
1804 // ld/scripttempl/elf.sc in the GNU linker. Note that the order of a
1805 // linker created section is normally set when the section is created;
1806 // this function is used for input sections.
1807
1808 Output_section_order
default_section_order(Output_section * os,bool is_relro_local)1809 Layout::default_section_order(Output_section* os, bool is_relro_local)
1810 {
1811 gold_assert((os->flags() & elfcpp::SHF_ALLOC) != 0);
1812 bool is_write = (os->flags() & elfcpp::SHF_WRITE) != 0;
1813 bool is_execinstr = (os->flags() & elfcpp::SHF_EXECINSTR) != 0;
1814 bool is_bss = false;
1815
1816 switch (os->type())
1817 {
1818 default:
1819 case elfcpp::SHT_PROGBITS:
1820 break;
1821 case elfcpp::SHT_NOBITS:
1822 is_bss = true;
1823 break;
1824 case elfcpp::SHT_RELA:
1825 case elfcpp::SHT_REL:
1826 if (!is_write)
1827 return ORDER_DYNAMIC_RELOCS;
1828 break;
1829 case elfcpp::SHT_HASH:
1830 case elfcpp::SHT_DYNAMIC:
1831 case elfcpp::SHT_SHLIB:
1832 case elfcpp::SHT_DYNSYM:
1833 case elfcpp::SHT_GNU_HASH:
1834 case elfcpp::SHT_GNU_verdef:
1835 case elfcpp::SHT_GNU_verneed:
1836 case elfcpp::SHT_GNU_versym:
1837 if (!is_write)
1838 return ORDER_DYNAMIC_LINKER;
1839 break;
1840 case elfcpp::SHT_NOTE:
1841 return is_write ? ORDER_RW_NOTE : ORDER_RO_NOTE;
1842 }
1843
1844 if ((os->flags() & elfcpp::SHF_TLS) != 0)
1845 return is_bss ? ORDER_TLS_BSS : ORDER_TLS_DATA;
1846
1847 if (!is_bss && !is_write)
1848 {
1849 if (is_execinstr)
1850 {
1851 if (strcmp(os->name(), ".init") == 0)
1852 return ORDER_INIT;
1853 else if (strcmp(os->name(), ".fini") == 0)
1854 return ORDER_FINI;
1855 }
1856 return is_execinstr ? ORDER_TEXT : ORDER_READONLY;
1857 }
1858
1859 if (os->is_relro())
1860 return is_relro_local ? ORDER_RELRO_LOCAL : ORDER_RELRO;
1861
1862 if (os->is_small_section())
1863 return is_bss ? ORDER_SMALL_BSS : ORDER_SMALL_DATA;
1864 if (os->is_large_section())
1865 return is_bss ? ORDER_LARGE_BSS : ORDER_LARGE_DATA;
1866
1867 return is_bss ? ORDER_BSS : ORDER_DATA;
1868 }
1869
1870 // Attach output sections to segments. This is called after we have
1871 // seen all the input sections.
1872
1873 void
attach_sections_to_segments(const Target * target)1874 Layout::attach_sections_to_segments(const Target* target)
1875 {
1876 for (Section_list::iterator p = this->section_list_.begin();
1877 p != this->section_list_.end();
1878 ++p)
1879 this->attach_section_to_segment(target, *p);
1880
1881 this->sections_are_attached_ = true;
1882 }
1883
1884 // Attach an output section to a segment.
1885
1886 void
attach_section_to_segment(const Target * target,Output_section * os)1887 Layout::attach_section_to_segment(const Target* target, Output_section* os)
1888 {
1889 if ((os->flags() & elfcpp::SHF_ALLOC) == 0)
1890 this->unattached_section_list_.push_back(os);
1891 else
1892 this->attach_allocated_section_to_segment(target, os);
1893 }
1894
1895 // Attach an allocated output section to a segment.
1896
1897 void
attach_allocated_section_to_segment(const Target * target,Output_section * os)1898 Layout::attach_allocated_section_to_segment(const Target* target,
1899 Output_section* os)
1900 {
1901 elfcpp::Elf_Xword flags = os->flags();
1902 gold_assert((flags & elfcpp::SHF_ALLOC) != 0);
1903
1904 if (parameters->options().relocatable())
1905 return;
1906
1907 // If we have a SECTIONS clause, we can't handle the attachment to
1908 // segments until after we've seen all the sections.
1909 if (this->script_options_->saw_sections_clause())
1910 return;
1911
1912 gold_assert(!this->script_options_->saw_phdrs_clause());
1913
1914 // This output section goes into a PT_LOAD segment.
1915
1916 elfcpp::Elf_Word seg_flags = Layout::section_flags_to_segment(flags);
1917
1918 // If this output section's segment has extra flags that need to be set,
1919 // coming from a linker plugin, do that.
1920 seg_flags |= os->extra_segment_flags();
1921
1922 // Check for --section-start.
1923 uint64_t addr;
1924 bool is_address_set = parameters->options().section_start(os->name(), &addr);
1925
1926 // In general the only thing we really care about for PT_LOAD
1927 // segments is whether or not they are writable or executable,
1928 // so that is how we search for them.
1929 // Large data sections also go into their own PT_LOAD segment.
1930 // People who need segments sorted on some other basis will
1931 // have to use a linker script.
1932
1933 Segment_list::const_iterator p;
1934 if (!os->is_unique_segment())
1935 {
1936 for (p = this->segment_list_.begin();
1937 p != this->segment_list_.end();
1938 ++p)
1939 {
1940 if ((*p)->type() != elfcpp::PT_LOAD)
1941 continue;
1942 if ((*p)->is_unique_segment())
1943 continue;
1944 if (!parameters->options().omagic()
1945 && ((*p)->flags() & elfcpp::PF_W) != (seg_flags & elfcpp::PF_W))
1946 continue;
1947 if ((target->isolate_execinstr() || parameters->options().rosegment())
1948 && ((*p)->flags() & elfcpp::PF_X) != (seg_flags & elfcpp::PF_X))
1949 continue;
1950 // If -Tbss was specified, we need to separate the data and BSS
1951 // segments.
1952 if (parameters->options().user_set_Tbss())
1953 {
1954 if ((os->type() == elfcpp::SHT_NOBITS)
1955 == (*p)->has_any_data_sections())
1956 continue;
1957 }
1958 if (os->is_large_data_section() && !(*p)->is_large_data_segment())
1959 continue;
1960
1961 if (is_address_set)
1962 {
1963 if ((*p)->are_addresses_set())
1964 continue;
1965
1966 (*p)->add_initial_output_data(os);
1967 (*p)->update_flags_for_output_section(seg_flags);
1968 (*p)->set_addresses(addr, addr);
1969 break;
1970 }
1971
1972 (*p)->add_output_section_to_load(this, os, seg_flags);
1973 break;
1974 }
1975 }
1976
1977 if (p == this->segment_list_.end()
1978 || os->is_unique_segment())
1979 {
1980 Output_segment* oseg = this->make_output_segment(elfcpp::PT_LOAD,
1981 seg_flags);
1982 if (os->is_large_data_section())
1983 oseg->set_is_large_data_segment();
1984 oseg->add_output_section_to_load(this, os, seg_flags);
1985 if (is_address_set)
1986 oseg->set_addresses(addr, addr);
1987 // Check if segment should be marked unique. For segments marked
1988 // unique by linker plugins, set the new alignment if specified.
1989 if (os->is_unique_segment())
1990 {
1991 oseg->set_is_unique_segment();
1992 if (os->segment_alignment() != 0)
1993 oseg->set_minimum_p_align(os->segment_alignment());
1994 }
1995 }
1996
1997 // If we see a loadable SHT_NOTE section, we create a PT_NOTE
1998 // segment.
1999 if (os->type() == elfcpp::SHT_NOTE)
2000 {
2001 // See if we already have an equivalent PT_NOTE segment.
2002 for (p = this->segment_list_.begin();
2003 p != segment_list_.end();
2004 ++p)
2005 {
2006 if ((*p)->type() == elfcpp::PT_NOTE
2007 && (((*p)->flags() & elfcpp::PF_W)
2008 == (seg_flags & elfcpp::PF_W)))
2009 {
2010 (*p)->add_output_section_to_nonload(os, seg_flags);
2011 break;
2012 }
2013 }
2014
2015 if (p == this->segment_list_.end())
2016 {
2017 Output_segment* oseg = this->make_output_segment(elfcpp::PT_NOTE,
2018 seg_flags);
2019 oseg->add_output_section_to_nonload(os, seg_flags);
2020 }
2021 }
2022
2023 // If we see a loadable SHF_TLS section, we create a PT_TLS
2024 // segment. There can only be one such segment.
2025 if ((flags & elfcpp::SHF_TLS) != 0)
2026 {
2027 if (this->tls_segment_ == NULL)
2028 this->make_output_segment(elfcpp::PT_TLS, seg_flags);
2029 this->tls_segment_->add_output_section_to_nonload(os, seg_flags);
2030 }
2031
2032 // If -z relro is in effect, and we see a relro section, we create a
2033 // PT_GNU_RELRO segment. There can only be one such segment.
2034 if (os->is_relro() && parameters->options().relro())
2035 {
2036 gold_assert(seg_flags == (elfcpp::PF_R | elfcpp::PF_W));
2037 if (this->relro_segment_ == NULL)
2038 this->make_output_segment(elfcpp::PT_GNU_RELRO, seg_flags);
2039 this->relro_segment_->add_output_section_to_nonload(os, seg_flags);
2040 }
2041
2042 // If we see a section named .interp, put it into a PT_INTERP
2043 // segment. This seems broken to me, but this is what GNU ld does,
2044 // and glibc expects it.
2045 if (strcmp(os->name(), ".interp") == 0
2046 && !this->script_options_->saw_phdrs_clause())
2047 {
2048 if (this->interp_segment_ == NULL)
2049 this->make_output_segment(elfcpp::PT_INTERP, seg_flags);
2050 else
2051 gold_warning(_("multiple '.interp' sections in input files "
2052 "may cause confusing PT_INTERP segment"));
2053 this->interp_segment_->add_output_section_to_nonload(os, seg_flags);
2054 }
2055 }
2056
2057 // Make an output section for a script.
2058
2059 Output_section*
make_output_section_for_script(const char * name,Script_sections::Section_type section_type)2060 Layout::make_output_section_for_script(
2061 const char* name,
2062 Script_sections::Section_type section_type)
2063 {
2064 name = this->namepool_.add(name, false, NULL);
2065 elfcpp::Elf_Xword sh_flags = elfcpp::SHF_ALLOC;
2066 if (section_type == Script_sections::ST_NOLOAD)
2067 sh_flags = 0;
2068 Output_section* os = this->make_output_section(name, elfcpp::SHT_PROGBITS,
2069 sh_flags, ORDER_INVALID,
2070 false);
2071 os->set_found_in_sections_clause();
2072 if (section_type == Script_sections::ST_NOLOAD)
2073 os->set_is_noload();
2074 return os;
2075 }
2076
2077 // Return the number of segments we expect to see.
2078
2079 size_t
expected_segment_count() const2080 Layout::expected_segment_count() const
2081 {
2082 size_t ret = this->segment_list_.size();
2083
2084 // If we didn't see a SECTIONS clause in a linker script, we should
2085 // already have the complete list of segments. Otherwise we ask the
2086 // SECTIONS clause how many segments it expects, and add in the ones
2087 // we already have (PT_GNU_STACK, PT_GNU_EH_FRAME, etc.)
2088
2089 if (!this->script_options_->saw_sections_clause())
2090 return ret;
2091 else
2092 {
2093 const Script_sections* ss = this->script_options_->script_sections();
2094 return ret + ss->expected_segment_count(this);
2095 }
2096 }
2097
2098 // Handle the .note.GNU-stack section at layout time. SEEN_GNU_STACK
2099 // is whether we saw a .note.GNU-stack section in the object file.
2100 // GNU_STACK_FLAGS is the section flags. The flags give the
2101 // protection required for stack memory. We record this in an
2102 // executable as a PT_GNU_STACK segment. If an object file does not
2103 // have a .note.GNU-stack segment, we must assume that it is an old
2104 // object. On some targets that will force an executable stack.
2105
2106 void
layout_gnu_stack(bool seen_gnu_stack,uint64_t gnu_stack_flags,const Object * obj)2107 Layout::layout_gnu_stack(bool seen_gnu_stack, uint64_t gnu_stack_flags,
2108 const Object* obj)
2109 {
2110 if (!seen_gnu_stack)
2111 {
2112 this->input_without_gnu_stack_note_ = true;
2113 if (parameters->options().warn_execstack()
2114 && parameters->target().is_default_stack_executable())
2115 gold_warning(_("%s: missing .note.GNU-stack section"
2116 " implies executable stack"),
2117 obj->name().c_str());
2118 }
2119 else
2120 {
2121 this->input_with_gnu_stack_note_ = true;
2122 if ((gnu_stack_flags & elfcpp::SHF_EXECINSTR) != 0)
2123 {
2124 this->input_requires_executable_stack_ = true;
2125 if (parameters->options().warn_execstack())
2126 gold_warning(_("%s: requires executable stack"),
2127 obj->name().c_str());
2128 }
2129 }
2130 }
2131
2132 // Create automatic note sections.
2133
2134 void
create_notes()2135 Layout::create_notes()
2136 {
2137 this->create_gold_note();
2138 this->create_stack_segment();
2139 this->create_build_id();
2140 }
2141
2142 // Create the dynamic sections which are needed before we read the
2143 // relocs.
2144
2145 void
create_initial_dynamic_sections(Symbol_table * symtab)2146 Layout::create_initial_dynamic_sections(Symbol_table* symtab)
2147 {
2148 if (parameters->doing_static_link())
2149 return;
2150
2151 this->dynamic_section_ = this->choose_output_section(NULL, ".dynamic",
2152 elfcpp::SHT_DYNAMIC,
2153 (elfcpp::SHF_ALLOC
2154 | elfcpp::SHF_WRITE),
2155 false, ORDER_RELRO,
2156 true);
2157
2158 // A linker script may discard .dynamic, so check for NULL.
2159 if (this->dynamic_section_ != NULL)
2160 {
2161 this->dynamic_symbol_ =
2162 symtab->define_in_output_data("_DYNAMIC", NULL,
2163 Symbol_table::PREDEFINED,
2164 this->dynamic_section_, 0, 0,
2165 elfcpp::STT_OBJECT, elfcpp::STB_LOCAL,
2166 elfcpp::STV_HIDDEN, 0, false, false);
2167
2168 this->dynamic_data_ = new Output_data_dynamic(&this->dynpool_);
2169
2170 this->dynamic_section_->add_output_section_data(this->dynamic_data_);
2171 }
2172 }
2173
2174 // For each output section whose name can be represented as C symbol,
2175 // define __start and __stop symbols for the section. This is a GNU
2176 // extension.
2177
2178 void
define_section_symbols(Symbol_table * symtab)2179 Layout::define_section_symbols(Symbol_table* symtab)
2180 {
2181 for (Section_list::const_iterator p = this->section_list_.begin();
2182 p != this->section_list_.end();
2183 ++p)
2184 {
2185 const char* const name = (*p)->name();
2186 if (is_cident(name))
2187 {
2188 const std::string name_string(name);
2189 const std::string start_name(cident_section_start_prefix
2190 + name_string);
2191 const std::string stop_name(cident_section_stop_prefix
2192 + name_string);
2193
2194 symtab->define_in_output_data(start_name.c_str(),
2195 NULL, // version
2196 Symbol_table::PREDEFINED,
2197 *p,
2198 0, // value
2199 0, // symsize
2200 elfcpp::STT_NOTYPE,
2201 elfcpp::STB_GLOBAL,
2202 elfcpp::STV_DEFAULT,
2203 0, // nonvis
2204 false, // offset_is_from_end
2205 true); // only_if_ref
2206
2207 symtab->define_in_output_data(stop_name.c_str(),
2208 NULL, // version
2209 Symbol_table::PREDEFINED,
2210 *p,
2211 0, // value
2212 0, // symsize
2213 elfcpp::STT_NOTYPE,
2214 elfcpp::STB_GLOBAL,
2215 elfcpp::STV_DEFAULT,
2216 0, // nonvis
2217 true, // offset_is_from_end
2218 true); // only_if_ref
2219 }
2220 }
2221 }
2222
2223 // Define symbols for group signatures.
2224
2225 void
define_group_signatures(Symbol_table * symtab)2226 Layout::define_group_signatures(Symbol_table* symtab)
2227 {
2228 for (Group_signatures::iterator p = this->group_signatures_.begin();
2229 p != this->group_signatures_.end();
2230 ++p)
2231 {
2232 Symbol* sym = symtab->lookup(p->signature, NULL);
2233 if (sym != NULL)
2234 p->section->set_info_symndx(sym);
2235 else
2236 {
2237 // Force the name of the group section to the group
2238 // signature, and use the group's section symbol as the
2239 // signature symbol.
2240 if (strcmp(p->section->name(), p->signature) != 0)
2241 {
2242 const char* name = this->namepool_.add(p->signature,
2243 true, NULL);
2244 p->section->set_name(name);
2245 }
2246 p->section->set_needs_symtab_index();
2247 p->section->set_info_section_symndx(p->section);
2248 }
2249 }
2250
2251 this->group_signatures_.clear();
2252 }
2253
2254 // Find the first read-only PT_LOAD segment, creating one if
2255 // necessary.
2256
2257 Output_segment*
find_first_load_seg(const Target * target)2258 Layout::find_first_load_seg(const Target* target)
2259 {
2260 Output_segment* best = NULL;
2261 for (Segment_list::const_iterator p = this->segment_list_.begin();
2262 p != this->segment_list_.end();
2263 ++p)
2264 {
2265 if ((*p)->type() == elfcpp::PT_LOAD
2266 && ((*p)->flags() & elfcpp::PF_R) != 0
2267 && (parameters->options().omagic()
2268 || ((*p)->flags() & elfcpp::PF_W) == 0)
2269 && (!target->isolate_execinstr()
2270 || ((*p)->flags() & elfcpp::PF_X) == 0))
2271 {
2272 if (best == NULL || this->segment_precedes(*p, best))
2273 best = *p;
2274 }
2275 }
2276 if (best != NULL)
2277 return best;
2278
2279 gold_assert(!this->script_options_->saw_phdrs_clause());
2280
2281 Output_segment* load_seg = this->make_output_segment(elfcpp::PT_LOAD,
2282 elfcpp::PF_R);
2283 return load_seg;
2284 }
2285
2286 // Save states of all current output segments. Store saved states
2287 // in SEGMENT_STATES.
2288
2289 void
save_segments(Segment_states * segment_states)2290 Layout::save_segments(Segment_states* segment_states)
2291 {
2292 for (Segment_list::const_iterator p = this->segment_list_.begin();
2293 p != this->segment_list_.end();
2294 ++p)
2295 {
2296 Output_segment* segment = *p;
2297 // Shallow copy.
2298 Output_segment* copy = new Output_segment(*segment);
2299 (*segment_states)[segment] = copy;
2300 }
2301 }
2302
2303 // Restore states of output segments and delete any segment not found in
2304 // SEGMENT_STATES.
2305
2306 void
restore_segments(const Segment_states * segment_states)2307 Layout::restore_segments(const Segment_states* segment_states)
2308 {
2309 // Go through the segment list and remove any segment added in the
2310 // relaxation loop.
2311 this->tls_segment_ = NULL;
2312 this->relro_segment_ = NULL;
2313 Segment_list::iterator list_iter = this->segment_list_.begin();
2314 while (list_iter != this->segment_list_.end())
2315 {
2316 Output_segment* segment = *list_iter;
2317 Segment_states::const_iterator states_iter =
2318 segment_states->find(segment);
2319 if (states_iter != segment_states->end())
2320 {
2321 const Output_segment* copy = states_iter->second;
2322 // Shallow copy to restore states.
2323 *segment = *copy;
2324
2325 // Also fix up TLS and RELRO segment pointers as appropriate.
2326 if (segment->type() == elfcpp::PT_TLS)
2327 this->tls_segment_ = segment;
2328 else if (segment->type() == elfcpp::PT_GNU_RELRO)
2329 this->relro_segment_ = segment;
2330
2331 ++list_iter;
2332 }
2333 else
2334 {
2335 list_iter = this->segment_list_.erase(list_iter);
2336 // This is a segment created during section layout. It should be
2337 // safe to remove it since we should have removed all pointers to it.
2338 delete segment;
2339 }
2340 }
2341 }
2342
2343 // Clean up after relaxation so that sections can be laid out again.
2344
2345 void
clean_up_after_relaxation()2346 Layout::clean_up_after_relaxation()
2347 {
2348 // Restore the segments to point state just prior to the relaxation loop.
2349 Script_sections* script_section = this->script_options_->script_sections();
2350 script_section->release_segments();
2351 this->restore_segments(this->segment_states_);
2352
2353 // Reset section addresses and file offsets
2354 for (Section_list::iterator p = this->section_list_.begin();
2355 p != this->section_list_.end();
2356 ++p)
2357 {
2358 (*p)->restore_states();
2359
2360 // If an input section changes size because of relaxation,
2361 // we need to adjust the section offsets of all input sections.
2362 // after such a section.
2363 if ((*p)->section_offsets_need_adjustment())
2364 (*p)->adjust_section_offsets();
2365
2366 (*p)->reset_address_and_file_offset();
2367 }
2368
2369 // Reset special output object address and file offsets.
2370 for (Data_list::iterator p = this->special_output_list_.begin();
2371 p != this->special_output_list_.end();
2372 ++p)
2373 (*p)->reset_address_and_file_offset();
2374
2375 // A linker script may have created some output section data objects.
2376 // They are useless now.
2377 for (Output_section_data_list::const_iterator p =
2378 this->script_output_section_data_list_.begin();
2379 p != this->script_output_section_data_list_.end();
2380 ++p)
2381 delete *p;
2382 this->script_output_section_data_list_.clear();
2383
2384 // Special-case fill output objects are recreated each time through
2385 // the relaxation loop.
2386 this->reset_relax_output();
2387 }
2388
2389 void
reset_relax_output()2390 Layout::reset_relax_output()
2391 {
2392 for (Data_list::const_iterator p = this->relax_output_list_.begin();
2393 p != this->relax_output_list_.end();
2394 ++p)
2395 delete *p;
2396 this->relax_output_list_.clear();
2397 }
2398
2399 // Prepare for relaxation.
2400
2401 void
prepare_for_relaxation()2402 Layout::prepare_for_relaxation()
2403 {
2404 // Create an relaxation debug check if in debugging mode.
2405 if (is_debugging_enabled(DEBUG_RELAXATION))
2406 this->relaxation_debug_check_ = new Relaxation_debug_check();
2407
2408 // Save segment states.
2409 this->segment_states_ = new Segment_states();
2410 this->save_segments(this->segment_states_);
2411
2412 for(Section_list::const_iterator p = this->section_list_.begin();
2413 p != this->section_list_.end();
2414 ++p)
2415 (*p)->save_states();
2416
2417 if (is_debugging_enabled(DEBUG_RELAXATION))
2418 this->relaxation_debug_check_->check_output_data_for_reset_values(
2419 this->section_list_, this->special_output_list_,
2420 this->relax_output_list_);
2421
2422 // Also enable recording of output section data from scripts.
2423 this->record_output_section_data_from_script_ = true;
2424 }
2425
2426 // If the user set the address of the text segment, that may not be
2427 // compatible with putting the segment headers and file headers into
2428 // that segment. For isolate_execinstr() targets, it's the rodata
2429 // segment rather than text where we might put the headers.
2430 static inline bool
load_seg_unusable_for_headers(const Target * target)2431 load_seg_unusable_for_headers(const Target* target)
2432 {
2433 const General_options& options = parameters->options();
2434 if (target->isolate_execinstr())
2435 return (options.user_set_Trodata_segment()
2436 && options.Trodata_segment() % target->abi_pagesize() != 0);
2437 else
2438 return (options.user_set_Ttext()
2439 && options.Ttext() % target->abi_pagesize() != 0);
2440 }
2441
2442 // Relaxation loop body: If target has no relaxation, this runs only once
2443 // Otherwise, the target relaxation hook is called at the end of
2444 // each iteration. If the hook returns true, it means re-layout of
2445 // section is required.
2446 //
2447 // The number of segments created by a linking script without a PHDRS
2448 // clause may be affected by section sizes and alignments. There is
2449 // a remote chance that relaxation causes different number of PT_LOAD
2450 // segments are created and sections are attached to different segments.
2451 // Therefore, we always throw away all segments created during section
2452 // layout. In order to be able to restart the section layout, we keep
2453 // a copy of the segment list right before the relaxation loop and use
2454 // that to restore the segments.
2455 //
2456 // PASS is the current relaxation pass number.
2457 // SYMTAB is a symbol table.
2458 // PLOAD_SEG is the address of a pointer for the load segment.
2459 // PHDR_SEG is a pointer to the PHDR segment.
2460 // SEGMENT_HEADERS points to the output segment header.
2461 // FILE_HEADER points to the output file header.
2462 // PSHNDX is the address to store the output section index.
2463
2464 off_t inline
relaxation_loop_body(int pass,Target * target,Symbol_table * symtab,Output_segment ** pload_seg,Output_segment * phdr_seg,Output_segment_headers * segment_headers,Output_file_header * file_header,unsigned int * pshndx)2465 Layout::relaxation_loop_body(
2466 int pass,
2467 Target* target,
2468 Symbol_table* symtab,
2469 Output_segment** pload_seg,
2470 Output_segment* phdr_seg,
2471 Output_segment_headers* segment_headers,
2472 Output_file_header* file_header,
2473 unsigned int* pshndx)
2474 {
2475 // If this is not the first iteration, we need to clean up after
2476 // relaxation so that we can lay out the sections again.
2477 if (pass != 0)
2478 this->clean_up_after_relaxation();
2479
2480 // If there is a SECTIONS clause, put all the input sections into
2481 // the required order.
2482 Output_segment* load_seg;
2483 if (this->script_options_->saw_sections_clause())
2484 load_seg = this->set_section_addresses_from_script(symtab);
2485 else if (parameters->options().relocatable())
2486 load_seg = NULL;
2487 else
2488 load_seg = this->find_first_load_seg(target);
2489
2490 if (parameters->options().oformat_enum()
2491 != General_options::OBJECT_FORMAT_ELF)
2492 load_seg = NULL;
2493
2494 if (load_seg_unusable_for_headers(target))
2495 {
2496 load_seg = NULL;
2497 phdr_seg = NULL;
2498 }
2499
2500 gold_assert(phdr_seg == NULL
2501 || load_seg != NULL
2502 || this->script_options_->saw_sections_clause());
2503
2504 // If the address of the load segment we found has been set by
2505 // --section-start rather than by a script, then adjust the VMA and
2506 // LMA downward if possible to include the file and section headers.
2507 uint64_t header_gap = 0;
2508 if (load_seg != NULL
2509 && load_seg->are_addresses_set()
2510 && !this->script_options_->saw_sections_clause()
2511 && !parameters->options().relocatable())
2512 {
2513 file_header->finalize_data_size();
2514 segment_headers->finalize_data_size();
2515 size_t sizeof_headers = (file_header->data_size()
2516 + segment_headers->data_size());
2517 const uint64_t abi_pagesize = target->abi_pagesize();
2518 uint64_t hdr_paddr = load_seg->paddr() - sizeof_headers;
2519 hdr_paddr &= ~(abi_pagesize - 1);
2520 uint64_t subtract = load_seg->paddr() - hdr_paddr;
2521 if (load_seg->paddr() < subtract || load_seg->vaddr() < subtract)
2522 load_seg = NULL;
2523 else
2524 {
2525 load_seg->set_addresses(load_seg->vaddr() - subtract,
2526 load_seg->paddr() - subtract);
2527 header_gap = subtract - sizeof_headers;
2528 }
2529 }
2530
2531 // Lay out the segment headers.
2532 if (!parameters->options().relocatable())
2533 {
2534 gold_assert(segment_headers != NULL);
2535 if (header_gap != 0 && load_seg != NULL)
2536 {
2537 Output_data_zero_fill* z = new Output_data_zero_fill(header_gap, 1);
2538 load_seg->add_initial_output_data(z);
2539 }
2540 if (load_seg != NULL)
2541 load_seg->add_initial_output_data(segment_headers);
2542 if (phdr_seg != NULL)
2543 phdr_seg->add_initial_output_data(segment_headers);
2544 }
2545
2546 // Lay out the file header.
2547 if (load_seg != NULL)
2548 load_seg->add_initial_output_data(file_header);
2549
2550 if (this->script_options_->saw_phdrs_clause()
2551 && !parameters->options().relocatable())
2552 {
2553 // Support use of FILEHDRS and PHDRS attachments in a PHDRS
2554 // clause in a linker script.
2555 Script_sections* ss = this->script_options_->script_sections();
2556 ss->put_headers_in_phdrs(file_header, segment_headers);
2557 }
2558
2559 // We set the output section indexes in set_segment_offsets and
2560 // set_section_indexes.
2561 *pshndx = 1;
2562
2563 // Set the file offsets of all the segments, and all the sections
2564 // they contain.
2565 off_t off;
2566 if (!parameters->options().relocatable())
2567 off = this->set_segment_offsets(target, load_seg, pshndx);
2568 else
2569 off = this->set_relocatable_section_offsets(file_header, pshndx);
2570
2571 // Verify that the dummy relaxation does not change anything.
2572 if (is_debugging_enabled(DEBUG_RELAXATION))
2573 {
2574 if (pass == 0)
2575 this->relaxation_debug_check_->read_sections(this->section_list_);
2576 else
2577 this->relaxation_debug_check_->verify_sections(this->section_list_);
2578 }
2579
2580 *pload_seg = load_seg;
2581 return off;
2582 }
2583
2584 // Search the list of patterns and find the postion of the given section
2585 // name in the output section. If the section name matches a glob
2586 // pattern and a non-glob name, then the non-glob position takes
2587 // precedence. Return 0 if no match is found.
2588
2589 unsigned int
find_section_order_index(const std::string & section_name)2590 Layout::find_section_order_index(const std::string& section_name)
2591 {
2592 Unordered_map<std::string, unsigned int>::iterator map_it;
2593 map_it = this->input_section_position_.find(section_name);
2594 if (map_it != this->input_section_position_.end())
2595 return map_it->second;
2596
2597 // Absolute match failed. Linear search the glob patterns.
2598 std::vector<std::string>::iterator it;
2599 for (it = this->input_section_glob_.begin();
2600 it != this->input_section_glob_.end();
2601 ++it)
2602 {
2603 if (fnmatch((*it).c_str(), section_name.c_str(), FNM_NOESCAPE) == 0)
2604 {
2605 map_it = this->input_section_position_.find(*it);
2606 gold_assert(map_it != this->input_section_position_.end());
2607 return map_it->second;
2608 }
2609 }
2610 return 0;
2611 }
2612
2613 // Read the sequence of input sections from the file specified with
2614 // option --section-ordering-file.
2615
2616 void
read_layout_from_file()2617 Layout::read_layout_from_file()
2618 {
2619 const char* filename = parameters->options().section_ordering_file();
2620 std::ifstream in;
2621 std::string line;
2622
2623 in.open(filename);
2624 if (!in)
2625 gold_fatal(_("unable to open --section-ordering-file file %s: %s"),
2626 filename, strerror(errno));
2627
2628 std::getline(in, line); // this chops off the trailing \n, if any
2629 unsigned int position = 1;
2630 this->set_section_ordering_specified();
2631
2632 while (in)
2633 {
2634 if (!line.empty() && line[line.length() - 1] == '\r') // Windows
2635 line.resize(line.length() - 1);
2636 // Ignore comments, beginning with '#'
2637 if (line[0] == '#')
2638 {
2639 std::getline(in, line);
2640 continue;
2641 }
2642 this->input_section_position_[line] = position;
2643 // Store all glob patterns in a vector.
2644 if (is_wildcard_string(line.c_str()))
2645 this->input_section_glob_.push_back(line);
2646 position++;
2647 std::getline(in, line);
2648 }
2649 }
2650
2651 // Finalize the layout. When this is called, we have created all the
2652 // output sections and all the output segments which are based on
2653 // input sections. We have several things to do, and we have to do
2654 // them in the right order, so that we get the right results correctly
2655 // and efficiently.
2656
2657 // 1) Finalize the list of output segments and create the segment
2658 // table header.
2659
2660 // 2) Finalize the dynamic symbol table and associated sections.
2661
2662 // 3) Determine the final file offset of all the output segments.
2663
2664 // 4) Determine the final file offset of all the SHF_ALLOC output
2665 // sections.
2666
2667 // 5) Create the symbol table sections and the section name table
2668 // section.
2669
2670 // 6) Finalize the symbol table: set symbol values to their final
2671 // value and make a final determination of which symbols are going
2672 // into the output symbol table.
2673
2674 // 7) Create the section table header.
2675
2676 // 8) Determine the final file offset of all the output sections which
2677 // are not SHF_ALLOC, including the section table header.
2678
2679 // 9) Finalize the ELF file header.
2680
2681 // This function returns the size of the output file.
2682
2683 off_t
finalize(const Input_objects * input_objects,Symbol_table * symtab,Target * target,const Task * task)2684 Layout::finalize(const Input_objects* input_objects, Symbol_table* symtab,
2685 Target* target, const Task* task)
2686 {
2687 target->finalize_sections(this, input_objects, symtab);
2688
2689 this->count_local_symbols(task, input_objects);
2690
2691 this->link_stabs_sections();
2692
2693 Output_segment* phdr_seg = NULL;
2694 if (!parameters->options().relocatable() && !parameters->doing_static_link())
2695 {
2696 // There was a dynamic object in the link. We need to create
2697 // some information for the dynamic linker.
2698
2699 // Create the PT_PHDR segment which will hold the program
2700 // headers.
2701 if (!this->script_options_->saw_phdrs_clause())
2702 phdr_seg = this->make_output_segment(elfcpp::PT_PHDR, elfcpp::PF_R);
2703
2704 // Create the dynamic symbol table, including the hash table.
2705 Output_section* dynstr;
2706 std::vector<Symbol*> dynamic_symbols;
2707 unsigned int local_dynamic_count;
2708 Versions versions(*this->script_options()->version_script_info(),
2709 &this->dynpool_);
2710 this->create_dynamic_symtab(input_objects, symtab, &dynstr,
2711 &local_dynamic_count, &dynamic_symbols,
2712 &versions);
2713
2714 // Create the .interp section to hold the name of the
2715 // interpreter, and put it in a PT_INTERP segment. Don't do it
2716 // if we saw a .interp section in an input file.
2717 if ((!parameters->options().shared()
2718 || parameters->options().dynamic_linker() != NULL)
2719 && this->interp_segment_ == NULL)
2720 this->create_interp(target);
2721
2722 // Finish the .dynamic section to hold the dynamic data, and put
2723 // it in a PT_DYNAMIC segment.
2724 this->finish_dynamic_section(input_objects, symtab);
2725
2726 // We should have added everything we need to the dynamic string
2727 // table.
2728 this->dynpool_.set_string_offsets();
2729
2730 // Create the version sections. We can't do this until the
2731 // dynamic string table is complete.
2732 this->create_version_sections(&versions, symtab, local_dynamic_count,
2733 dynamic_symbols, dynstr);
2734
2735 // Set the size of the _DYNAMIC symbol. We can't do this until
2736 // after we call create_version_sections.
2737 this->set_dynamic_symbol_size(symtab);
2738 }
2739
2740 // Create segment headers.
2741 Output_segment_headers* segment_headers =
2742 (parameters->options().relocatable()
2743 ? NULL
2744 : new Output_segment_headers(this->segment_list_));
2745
2746 // Lay out the file header.
2747 Output_file_header* file_header = new Output_file_header(target, symtab,
2748 segment_headers);
2749
2750 this->special_output_list_.push_back(file_header);
2751 if (segment_headers != NULL)
2752 this->special_output_list_.push_back(segment_headers);
2753
2754 // Find approriate places for orphan output sections if we are using
2755 // a linker script.
2756 if (this->script_options_->saw_sections_clause())
2757 this->place_orphan_sections_in_script();
2758
2759 Output_segment* load_seg;
2760 off_t off;
2761 unsigned int shndx;
2762 int pass = 0;
2763
2764 // Take a snapshot of the section layout as needed.
2765 if (target->may_relax())
2766 this->prepare_for_relaxation();
2767
2768 // Run the relaxation loop to lay out sections.
2769 do
2770 {
2771 off = this->relaxation_loop_body(pass, target, symtab, &load_seg,
2772 phdr_seg, segment_headers, file_header,
2773 &shndx);
2774 pass++;
2775 }
2776 while (target->may_relax()
2777 && target->relax(pass, input_objects, symtab, this, task));
2778
2779 // Check if data segment size is less than the safe value with PIE links.
2780 if (parameters->options().pie() && target->max_pie_data_segment_size())
2781 {
2782 Segment_list::const_iterator p;
2783 uint64_t re_vaddr = 0, re_memsz = 0, rw_vaddr = 0, rw_memsz = 0;
2784 uint64_t data_seg_size = 0;
2785 for (p = this->segment_list_.begin();
2786 p != this->segment_list_.end();
2787 ++p)
2788 {
2789 // With -Wl,--rosegment, note the end addr of "R E" segment.
2790 if (parameters->options().rosegment()
2791 && (*p)->type() == elfcpp::PT_LOAD
2792 && ((*p)->flags() & elfcpp::PF_X) != 0
2793 && ((*p)->flags() & elfcpp::PF_R) != 0)
2794 {
2795 re_vaddr = (*p)->vaddr();
2796 re_memsz = (*p)->memsz();
2797 continue;
2798 }
2799 if ((*p)->type() == elfcpp::PT_LOAD
2800 && ((*p)->flags() & elfcpp::PF_W) != 0
2801 && ((*p)->flags() & elfcpp::PF_R) != 0)
2802 {
2803 rw_vaddr = (*p)->vaddr();
2804 rw_memsz = (*p)->memsz();
2805 break;
2806 }
2807 }
2808
2809 // With -Wl,--rosegment, report data segment size as delta of end of
2810 // "RW" segment and end of "R E" segment. Otherwise, data segment
2811 // size is just the memsz of "RW" segment.
2812 if (parameters->options().rosegment())
2813 data_seg_size = (rw_vaddr + rw_memsz) - (re_vaddr + re_memsz);
2814 else
2815 data_seg_size = rw_memsz;
2816
2817 if (data_seg_size >= target->max_pie_data_segment_size())
2818 gold_warning(
2819 _("Unsafe PIE data segment size (%" PRIu64 " > %" PRIu64 "). "
2820 "For kernels with CONFIG_ARCH_BINFMT_ELF_RANDOMIZE_PIE enabled, "
2821 "load_elf_binary() attempts to map a PIE binary into an address "
2822 "range immediately below mm->mmap_base. The first PT_LOAD segment "
2823 "is mapped below mm->mmap_base, the subsequent PT_LOAD segment(s) "
2824 "end up being mapped above mm->mmap_base into the area that is "
2825 "supposed to be the \"gap\" between the stack and the binary. Since"
2826 " the size of the \"gap\" on x86_64 is only guaranteed to be 128MB "
2827 "this means that binaries with large data segments > 128MB can end "
2828 "up mapping part of their data segment over their stack resulting "
2829 "in corruption of the stack. Any PIE binary with a data segment > "
2830 "128MB is vulnerable to this. It is suggested to turn off PIE."),
2831 data_seg_size,
2832 target->max_pie_data_segment_size());
2833 }
2834
2835 // If there is a load segment that contains the file and program headers,
2836 // provide a symbol __ehdr_start pointing there.
2837 // A program can use this to examine itself robustly.
2838 Symbol *ehdr_start = symtab->lookup("__ehdr_start");
2839 if (ehdr_start != NULL && ehdr_start->is_predefined())
2840 {
2841 if (load_seg != NULL)
2842 ehdr_start->set_output_segment(load_seg, Symbol::SEGMENT_START);
2843 else
2844 ehdr_start->set_undefined();
2845 }
2846
2847 // Set the file offsets of all the non-data sections we've seen so
2848 // far which don't have to wait for the input sections. We need
2849 // this in order to finalize local symbols in non-allocated
2850 // sections.
2851 off = this->set_section_offsets(off, BEFORE_INPUT_SECTIONS_PASS);
2852
2853 // Set the section indexes of all unallocated sections seen so far,
2854 // in case any of them are somehow referenced by a symbol.
2855 shndx = this->set_section_indexes(shndx);
2856
2857 // Create the symbol table sections.
2858 this->create_symtab_sections(input_objects, symtab, shndx, &off);
2859 if (!parameters->doing_static_link())
2860 this->assign_local_dynsym_offsets(input_objects);
2861
2862 // Process any symbol assignments from a linker script. This must
2863 // be called after the symbol table has been finalized.
2864 this->script_options_->finalize_symbols(symtab, this);
2865
2866 // Create the incremental inputs sections.
2867 if (this->incremental_inputs_)
2868 {
2869 this->incremental_inputs_->finalize();
2870 this->create_incremental_info_sections(symtab);
2871 }
2872
2873 // Create the .shstrtab section.
2874 Output_section* shstrtab_section = this->create_shstrtab();
2875
2876 // Set the file offsets of the rest of the non-data sections which
2877 // don't have to wait for the input sections.
2878 off = this->set_section_offsets(off, BEFORE_INPUT_SECTIONS_PASS);
2879
2880 // Now that all sections have been created, set the section indexes
2881 // for any sections which haven't been done yet.
2882 shndx = this->set_section_indexes(shndx);
2883
2884 // Create the section table header.
2885 this->create_shdrs(shstrtab_section, &off);
2886
2887 // If there are no sections which require postprocessing, we can
2888 // handle the section names now, and avoid a resize later.
2889 if (!this->any_postprocessing_sections_)
2890 {
2891 off = this->set_section_offsets(off,
2892 POSTPROCESSING_SECTIONS_PASS);
2893 off =
2894 this->set_section_offsets(off,
2895 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS);
2896 }
2897
2898 file_header->set_section_info(this->section_headers_, shstrtab_section);
2899
2900 // Now we know exactly where everything goes in the output file
2901 // (except for non-allocated sections which require postprocessing).
2902 Output_data::layout_complete();
2903
2904 this->output_file_size_ = off;
2905
2906 return off;
2907 }
2908
2909 // Create a note header following the format defined in the ELF ABI.
2910 // NAME is the name, NOTE_TYPE is the type, SECTION_NAME is the name
2911 // of the section to create, DESCSZ is the size of the descriptor.
2912 // ALLOCATE is true if the section should be allocated in memory.
2913 // This returns the new note section. It sets *TRAILING_PADDING to
2914 // the number of trailing zero bytes required.
2915
2916 Output_section*
create_note(const char * name,int note_type,const char * section_name,size_t descsz,bool allocate,size_t * trailing_padding)2917 Layout::create_note(const char* name, int note_type,
2918 const char* section_name, size_t descsz,
2919 bool allocate, size_t* trailing_padding)
2920 {
2921 // Authorities all agree that the values in a .note field should
2922 // be aligned on 4-byte boundaries for 32-bit binaries. However,
2923 // they differ on what the alignment is for 64-bit binaries.
2924 // The GABI says unambiguously they take 8-byte alignment:
2925 // http://sco.com/developers/gabi/latest/ch5.pheader.html#note_section
2926 // Other documentation says alignment should always be 4 bytes:
2927 // http://www.netbsd.org/docs/kernel/elf-notes.html#note-format
2928 // GNU ld and GNU readelf both support the latter (at least as of
2929 // version 2.16.91), and glibc always generates the latter for
2930 // .note.ABI-tag (as of version 1.6), so that's the one we go with
2931 // here.
2932 #ifdef GABI_FORMAT_FOR_DOTNOTE_SECTION // This is not defined by default.
2933 const int size = parameters->target().get_size();
2934 #else
2935 const int size = 32;
2936 #endif
2937
2938 // The contents of the .note section.
2939 size_t namesz = strlen(name) + 1;
2940 size_t aligned_namesz = align_address(namesz, size / 8);
2941 size_t aligned_descsz = align_address(descsz, size / 8);
2942
2943 size_t notehdrsz = 3 * (size / 8) + aligned_namesz;
2944
2945 unsigned char* buffer = new unsigned char[notehdrsz];
2946 memset(buffer, 0, notehdrsz);
2947
2948 bool is_big_endian = parameters->target().is_big_endian();
2949
2950 if (size == 32)
2951 {
2952 if (!is_big_endian)
2953 {
2954 elfcpp::Swap<32, false>::writeval(buffer, namesz);
2955 elfcpp::Swap<32, false>::writeval(buffer + 4, descsz);
2956 elfcpp::Swap<32, false>::writeval(buffer + 8, note_type);
2957 }
2958 else
2959 {
2960 elfcpp::Swap<32, true>::writeval(buffer, namesz);
2961 elfcpp::Swap<32, true>::writeval(buffer + 4, descsz);
2962 elfcpp::Swap<32, true>::writeval(buffer + 8, note_type);
2963 }
2964 }
2965 else if (size == 64)
2966 {
2967 if (!is_big_endian)
2968 {
2969 elfcpp::Swap<64, false>::writeval(buffer, namesz);
2970 elfcpp::Swap<64, false>::writeval(buffer + 8, descsz);
2971 elfcpp::Swap<64, false>::writeval(buffer + 16, note_type);
2972 }
2973 else
2974 {
2975 elfcpp::Swap<64, true>::writeval(buffer, namesz);
2976 elfcpp::Swap<64, true>::writeval(buffer + 8, descsz);
2977 elfcpp::Swap<64, true>::writeval(buffer + 16, note_type);
2978 }
2979 }
2980 else
2981 gold_unreachable();
2982
2983 memcpy(buffer + 3 * (size / 8), name, namesz);
2984
2985 elfcpp::Elf_Xword flags = 0;
2986 Output_section_order order = ORDER_INVALID;
2987 if (allocate)
2988 {
2989 flags = elfcpp::SHF_ALLOC;
2990 order = ORDER_RO_NOTE;
2991 }
2992 Output_section* os = this->choose_output_section(NULL, section_name,
2993 elfcpp::SHT_NOTE,
2994 flags, false, order, false);
2995 if (os == NULL)
2996 return NULL;
2997
2998 Output_section_data* posd = new Output_data_const_buffer(buffer, notehdrsz,
2999 size / 8,
3000 "** note header");
3001 os->add_output_section_data(posd);
3002
3003 *trailing_padding = aligned_descsz - descsz;
3004
3005 return os;
3006 }
3007
3008 // For an executable or shared library, create a note to record the
3009 // version of gold used to create the binary.
3010
3011 void
create_gold_note()3012 Layout::create_gold_note()
3013 {
3014 if (parameters->options().relocatable()
3015 || parameters->incremental_update())
3016 return;
3017
3018 std::string desc = std::string("gold ") + gold::get_version_string();
3019
3020 size_t trailing_padding;
3021 Output_section* os = this->create_note("GNU", elfcpp::NT_GNU_GOLD_VERSION,
3022 ".note.gnu.gold-version", desc.size(),
3023 false, &trailing_padding);
3024 if (os == NULL)
3025 return;
3026
3027 Output_section_data* posd = new Output_data_const(desc, 4);
3028 os->add_output_section_data(posd);
3029
3030 if (trailing_padding > 0)
3031 {
3032 posd = new Output_data_zero_fill(trailing_padding, 0);
3033 os->add_output_section_data(posd);
3034 }
3035 }
3036
3037 // Record whether the stack should be executable. This can be set
3038 // from the command line using the -z execstack or -z noexecstack
3039 // options. Otherwise, if any input file has a .note.GNU-stack
3040 // section with the SHF_EXECINSTR flag set, the stack should be
3041 // executable. Otherwise, if at least one input file a
3042 // .note.GNU-stack section, and some input file has no .note.GNU-stack
3043 // section, we use the target default for whether the stack should be
3044 // executable. If -z stack-size was used to set a p_memsz value for
3045 // PT_GNU_STACK, we generate the segment regardless. Otherwise, we
3046 // don't generate a stack note. When generating a object file, we
3047 // create a .note.GNU-stack section with the appropriate marking.
3048 // When generating an executable or shared library, we create a
3049 // PT_GNU_STACK segment.
3050
3051 void
create_stack_segment()3052 Layout::create_stack_segment()
3053 {
3054 bool is_stack_executable;
3055 if (parameters->options().is_execstack_set())
3056 {
3057 is_stack_executable = parameters->options().is_stack_executable();
3058 if (!is_stack_executable
3059 && this->input_requires_executable_stack_
3060 && parameters->options().warn_execstack())
3061 gold_warning(_("one or more inputs require executable stack, "
3062 "but -z noexecstack was given"));
3063 }
3064 else if (!this->input_with_gnu_stack_note_
3065 && (!parameters->options().user_set_stack_size()
3066 || parameters->options().relocatable()))
3067 return;
3068 else
3069 {
3070 if (this->input_requires_executable_stack_)
3071 is_stack_executable = true;
3072 else if (this->input_without_gnu_stack_note_)
3073 is_stack_executable =
3074 parameters->target().is_default_stack_executable();
3075 else
3076 is_stack_executable = false;
3077 }
3078
3079 if (parameters->options().relocatable())
3080 {
3081 const char* name = this->namepool_.add(".note.GNU-stack", false, NULL);
3082 elfcpp::Elf_Xword flags = 0;
3083 if (is_stack_executable)
3084 flags |= elfcpp::SHF_EXECINSTR;
3085 this->make_output_section(name, elfcpp::SHT_PROGBITS, flags,
3086 ORDER_INVALID, false);
3087 }
3088 else
3089 {
3090 if (this->script_options_->saw_phdrs_clause())
3091 return;
3092 int flags = elfcpp::PF_R | elfcpp::PF_W;
3093 if (is_stack_executable)
3094 flags |= elfcpp::PF_X;
3095 Output_segment* seg =
3096 this->make_output_segment(elfcpp::PT_GNU_STACK, flags);
3097 seg->set_size(parameters->options().stack_size());
3098 // BFD lets targets override this default alignment, but the only
3099 // targets that do so are ones that Gold does not support so far.
3100 seg->set_minimum_p_align(16);
3101 }
3102 }
3103
3104 // If --build-id was used, set up the build ID note.
3105
3106 void
create_build_id()3107 Layout::create_build_id()
3108 {
3109 if (!parameters->options().user_set_build_id())
3110 return;
3111
3112 const char* style = parameters->options().build_id();
3113 if (strcmp(style, "none") == 0)
3114 return;
3115
3116 // Set DESCSZ to the size of the note descriptor. When possible,
3117 // set DESC to the note descriptor contents.
3118 size_t descsz;
3119 std::string desc;
3120 if (strcmp(style, "md5") == 0)
3121 descsz = 128 / 8;
3122 else if ((strcmp(style, "sha1") == 0) || (strcmp(style, "tree") == 0))
3123 descsz = 160 / 8;
3124 else if (strcmp(style, "uuid") == 0)
3125 {
3126 const size_t uuidsz = 128 / 8;
3127
3128 char buffer[uuidsz];
3129 memset(buffer, 0, uuidsz);
3130
3131 int descriptor = open_descriptor(-1, "/dev/urandom", O_RDONLY);
3132 if (descriptor < 0)
3133 gold_error(_("--build-id=uuid failed: could not open /dev/urandom: %s"),
3134 strerror(errno));
3135 else
3136 {
3137 ssize_t got = ::read(descriptor, buffer, uuidsz);
3138 release_descriptor(descriptor, true);
3139 if (got < 0)
3140 gold_error(_("/dev/urandom: read failed: %s"), strerror(errno));
3141 else if (static_cast<size_t>(got) != uuidsz)
3142 gold_error(_("/dev/urandom: expected %zu bytes, got %zd bytes"),
3143 uuidsz, got);
3144 }
3145
3146 desc.assign(buffer, uuidsz);
3147 descsz = uuidsz;
3148 }
3149 else if (strncmp(style, "0x", 2) == 0)
3150 {
3151 hex_init();
3152 const char* p = style + 2;
3153 while (*p != '\0')
3154 {
3155 if (hex_p(p[0]) && hex_p(p[1]))
3156 {
3157 char c = (hex_value(p[0]) << 4) | hex_value(p[1]);
3158 desc += c;
3159 p += 2;
3160 }
3161 else if (*p == '-' || *p == ':')
3162 ++p;
3163 else
3164 gold_fatal(_("--build-id argument '%s' not a valid hex number"),
3165 style);
3166 }
3167 descsz = desc.size();
3168 }
3169 else
3170 gold_fatal(_("unrecognized --build-id argument '%s'"), style);
3171
3172 // Create the note.
3173 size_t trailing_padding;
3174 Output_section* os = this->create_note("GNU", elfcpp::NT_GNU_BUILD_ID,
3175 ".note.gnu.build-id", descsz, true,
3176 &trailing_padding);
3177 if (os == NULL)
3178 return;
3179
3180 if (!desc.empty())
3181 {
3182 // We know the value already, so we fill it in now.
3183 gold_assert(desc.size() == descsz);
3184
3185 Output_section_data* posd = new Output_data_const(desc, 4);
3186 os->add_output_section_data(posd);
3187
3188 if (trailing_padding != 0)
3189 {
3190 posd = new Output_data_zero_fill(trailing_padding, 0);
3191 os->add_output_section_data(posd);
3192 }
3193 }
3194 else
3195 {
3196 // We need to compute a checksum after we have completed the
3197 // link.
3198 gold_assert(trailing_padding == 0);
3199 this->build_id_note_ = new Output_data_zero_fill(descsz, 4);
3200 os->add_output_section_data(this->build_id_note_);
3201 }
3202 }
3203
3204 // If we have both .stabXX and .stabXXstr sections, then the sh_link
3205 // field of the former should point to the latter. I'm not sure who
3206 // started this, but the GNU linker does it, and some tools depend
3207 // upon it.
3208
3209 void
link_stabs_sections()3210 Layout::link_stabs_sections()
3211 {
3212 if (!this->have_stabstr_section_)
3213 return;
3214
3215 for (Section_list::iterator p = this->section_list_.begin();
3216 p != this->section_list_.end();
3217 ++p)
3218 {
3219 if ((*p)->type() != elfcpp::SHT_STRTAB)
3220 continue;
3221
3222 const char* name = (*p)->name();
3223 if (strncmp(name, ".stab", 5) != 0)
3224 continue;
3225
3226 size_t len = strlen(name);
3227 if (strcmp(name + len - 3, "str") != 0)
3228 continue;
3229
3230 std::string stab_name(name, len - 3);
3231 Output_section* stab_sec;
3232 stab_sec = this->find_output_section(stab_name.c_str());
3233 if (stab_sec != NULL)
3234 stab_sec->set_link_section(*p);
3235 }
3236 }
3237
3238 // Create .gnu_incremental_inputs and related sections needed
3239 // for the next run of incremental linking to check what has changed.
3240
3241 void
create_incremental_info_sections(Symbol_table * symtab)3242 Layout::create_incremental_info_sections(Symbol_table* symtab)
3243 {
3244 Incremental_inputs* incr = this->incremental_inputs_;
3245
3246 gold_assert(incr != NULL);
3247
3248 // Create the .gnu_incremental_inputs, _symtab, and _relocs input sections.
3249 incr->create_data_sections(symtab);
3250
3251 // Add the .gnu_incremental_inputs section.
3252 const char* incremental_inputs_name =
3253 this->namepool_.add(".gnu_incremental_inputs", false, NULL);
3254 Output_section* incremental_inputs_os =
3255 this->make_output_section(incremental_inputs_name,
3256 elfcpp::SHT_GNU_INCREMENTAL_INPUTS, 0,
3257 ORDER_INVALID, false);
3258 incremental_inputs_os->add_output_section_data(incr->inputs_section());
3259
3260 // Add the .gnu_incremental_symtab section.
3261 const char* incremental_symtab_name =
3262 this->namepool_.add(".gnu_incremental_symtab", false, NULL);
3263 Output_section* incremental_symtab_os =
3264 this->make_output_section(incremental_symtab_name,
3265 elfcpp::SHT_GNU_INCREMENTAL_SYMTAB, 0,
3266 ORDER_INVALID, false);
3267 incremental_symtab_os->add_output_section_data(incr->symtab_section());
3268 incremental_symtab_os->set_entsize(4);
3269
3270 // Add the .gnu_incremental_relocs section.
3271 const char* incremental_relocs_name =
3272 this->namepool_.add(".gnu_incremental_relocs", false, NULL);
3273 Output_section* incremental_relocs_os =
3274 this->make_output_section(incremental_relocs_name,
3275 elfcpp::SHT_GNU_INCREMENTAL_RELOCS, 0,
3276 ORDER_INVALID, false);
3277 incremental_relocs_os->add_output_section_data(incr->relocs_section());
3278 incremental_relocs_os->set_entsize(incr->relocs_entsize());
3279
3280 // Add the .gnu_incremental_got_plt section.
3281 const char* incremental_got_plt_name =
3282 this->namepool_.add(".gnu_incremental_got_plt", false, NULL);
3283 Output_section* incremental_got_plt_os =
3284 this->make_output_section(incremental_got_plt_name,
3285 elfcpp::SHT_GNU_INCREMENTAL_GOT_PLT, 0,
3286 ORDER_INVALID, false);
3287 incremental_got_plt_os->add_output_section_data(incr->got_plt_section());
3288
3289 // Add the .gnu_incremental_strtab section.
3290 const char* incremental_strtab_name =
3291 this->namepool_.add(".gnu_incremental_strtab", false, NULL);
3292 Output_section* incremental_strtab_os = this->make_output_section(incremental_strtab_name,
3293 elfcpp::SHT_STRTAB, 0,
3294 ORDER_INVALID, false);
3295 Output_data_strtab* strtab_data =
3296 new Output_data_strtab(incr->get_stringpool());
3297 incremental_strtab_os->add_output_section_data(strtab_data);
3298
3299 incremental_inputs_os->set_after_input_sections();
3300 incremental_symtab_os->set_after_input_sections();
3301 incremental_relocs_os->set_after_input_sections();
3302 incremental_got_plt_os->set_after_input_sections();
3303
3304 incremental_inputs_os->set_link_section(incremental_strtab_os);
3305 incremental_symtab_os->set_link_section(incremental_inputs_os);
3306 incremental_relocs_os->set_link_section(incremental_inputs_os);
3307 incremental_got_plt_os->set_link_section(incremental_inputs_os);
3308 }
3309
3310 // Return whether SEG1 should be before SEG2 in the output file. This
3311 // is based entirely on the segment type and flags. When this is
3312 // called the segment addresses have normally not yet been set.
3313
3314 bool
segment_precedes(const Output_segment * seg1,const Output_segment * seg2)3315 Layout::segment_precedes(const Output_segment* seg1,
3316 const Output_segment* seg2)
3317 {
3318 elfcpp::Elf_Word type1 = seg1->type();
3319 elfcpp::Elf_Word type2 = seg2->type();
3320
3321 // The single PT_PHDR segment is required to precede any loadable
3322 // segment. We simply make it always first.
3323 if (type1 == elfcpp::PT_PHDR)
3324 {
3325 gold_assert(type2 != elfcpp::PT_PHDR);
3326 return true;
3327 }
3328 if (type2 == elfcpp::PT_PHDR)
3329 return false;
3330
3331 // The single PT_INTERP segment is required to precede any loadable
3332 // segment. We simply make it always second.
3333 if (type1 == elfcpp::PT_INTERP)
3334 {
3335 gold_assert(type2 != elfcpp::PT_INTERP);
3336 return true;
3337 }
3338 if (type2 == elfcpp::PT_INTERP)
3339 return false;
3340
3341 // We then put PT_LOAD segments before any other segments.
3342 if (type1 == elfcpp::PT_LOAD && type2 != elfcpp::PT_LOAD)
3343 return true;
3344 if (type2 == elfcpp::PT_LOAD && type1 != elfcpp::PT_LOAD)
3345 return false;
3346
3347 // We put the PT_TLS segment last except for the PT_GNU_RELRO
3348 // segment, because that is where the dynamic linker expects to find
3349 // it (this is just for efficiency; other positions would also work
3350 // correctly).
3351 if (type1 == elfcpp::PT_TLS
3352 && type2 != elfcpp::PT_TLS
3353 && type2 != elfcpp::PT_GNU_RELRO)
3354 return false;
3355 if (type2 == elfcpp::PT_TLS
3356 && type1 != elfcpp::PT_TLS
3357 && type1 != elfcpp::PT_GNU_RELRO)
3358 return true;
3359
3360 // We put the PT_GNU_RELRO segment last, because that is where the
3361 // dynamic linker expects to find it (as with PT_TLS, this is just
3362 // for efficiency).
3363 if (type1 == elfcpp::PT_GNU_RELRO && type2 != elfcpp::PT_GNU_RELRO)
3364 return false;
3365 if (type2 == elfcpp::PT_GNU_RELRO && type1 != elfcpp::PT_GNU_RELRO)
3366 return true;
3367
3368 const elfcpp::Elf_Word flags1 = seg1->flags();
3369 const elfcpp::Elf_Word flags2 = seg2->flags();
3370
3371 // The order of non-PT_LOAD segments is unimportant. We simply sort
3372 // by the numeric segment type and flags values. There should not
3373 // be more than one segment with the same type and flags, except
3374 // when a linker script specifies such.
3375 if (type1 != elfcpp::PT_LOAD)
3376 {
3377 if (type1 != type2)
3378 return type1 < type2;
3379 gold_assert(flags1 != flags2
3380 || this->script_options_->saw_phdrs_clause());
3381 return flags1 < flags2;
3382 }
3383
3384 // If the addresses are set already, sort by load address.
3385 if (seg1->are_addresses_set())
3386 {
3387 if (!seg2->are_addresses_set())
3388 return true;
3389
3390 unsigned int section_count1 = seg1->output_section_count();
3391 unsigned int section_count2 = seg2->output_section_count();
3392 if (section_count1 == 0 && section_count2 > 0)
3393 return true;
3394 if (section_count1 > 0 && section_count2 == 0)
3395 return false;
3396
3397 uint64_t paddr1 = (seg1->are_addresses_set()
3398 ? seg1->paddr()
3399 : seg1->first_section_load_address());
3400 uint64_t paddr2 = (seg2->are_addresses_set()
3401 ? seg2->paddr()
3402 : seg2->first_section_load_address());
3403
3404 if (paddr1 != paddr2)
3405 return paddr1 < paddr2;
3406 }
3407 else if (seg2->are_addresses_set())
3408 return false;
3409
3410 // A segment which holds large data comes after a segment which does
3411 // not hold large data.
3412 if (seg1->is_large_data_segment())
3413 {
3414 if (!seg2->is_large_data_segment())
3415 return false;
3416 }
3417 else if (seg2->is_large_data_segment())
3418 return true;
3419
3420 // Otherwise, we sort PT_LOAD segments based on the flags. Readonly
3421 // segments come before writable segments. Then writable segments
3422 // with data come before writable segments without data. Then
3423 // executable segments come before non-executable segments. Then
3424 // the unlikely case of a non-readable segment comes before the
3425 // normal case of a readable segment. If there are multiple
3426 // segments with the same type and flags, we require that the
3427 // address be set, and we sort by virtual address and then physical
3428 // address.
3429 if ((flags1 & elfcpp::PF_W) != (flags2 & elfcpp::PF_W))
3430 return (flags1 & elfcpp::PF_W) == 0;
3431 if ((flags1 & elfcpp::PF_W) != 0
3432 && seg1->has_any_data_sections() != seg2->has_any_data_sections())
3433 return seg1->has_any_data_sections();
3434 if ((flags1 & elfcpp::PF_X) != (flags2 & elfcpp::PF_X))
3435 return (flags1 & elfcpp::PF_X) != 0;
3436 if ((flags1 & elfcpp::PF_R) != (flags2 & elfcpp::PF_R))
3437 return (flags1 & elfcpp::PF_R) == 0;
3438
3439 // We shouldn't get here--we shouldn't create segments which we
3440 // can't distinguish. Unless of course we are using a weird linker
3441 // script or overlapping --section-start options. We could also get
3442 // here if plugins want unique segments for subsets of sections.
3443 gold_assert(this->script_options_->saw_phdrs_clause()
3444 || parameters->options().any_section_start()
3445 || this->is_unique_segment_for_sections_specified());
3446 return false;
3447 }
3448
3449 // Increase OFF so that it is congruent to ADDR modulo ABI_PAGESIZE.
3450
3451 static off_t
align_file_offset(off_t off,uint64_t addr,uint64_t abi_pagesize)3452 align_file_offset(off_t off, uint64_t addr, uint64_t abi_pagesize)
3453 {
3454 uint64_t unsigned_off = off;
3455 uint64_t aligned_off = ((unsigned_off & ~(abi_pagesize - 1))
3456 | (addr & (abi_pagesize - 1)));
3457 if (aligned_off < unsigned_off)
3458 aligned_off += abi_pagesize;
3459 return aligned_off;
3460 }
3461
3462 // On targets where the text segment contains only executable code,
3463 // a non-executable segment is never the text segment.
3464
3465 static inline bool
is_text_segment(const Target * target,const Output_segment * seg)3466 is_text_segment(const Target* target, const Output_segment* seg)
3467 {
3468 elfcpp::Elf_Xword flags = seg->flags();
3469 if ((flags & elfcpp::PF_W) != 0)
3470 return false;
3471 if ((flags & elfcpp::PF_X) == 0)
3472 return !target->isolate_execinstr();
3473 return true;
3474 }
3475
3476 // Set the file offsets of all the segments, and all the sections they
3477 // contain. They have all been created. LOAD_SEG must be be laid out
3478 // first. Return the offset of the data to follow.
3479
3480 off_t
set_segment_offsets(const Target * target,Output_segment * load_seg,unsigned int * pshndx)3481 Layout::set_segment_offsets(const Target* target, Output_segment* load_seg,
3482 unsigned int* pshndx)
3483 {
3484 // Sort them into the final order. We use a stable sort so that we
3485 // don't randomize the order of indistinguishable segments created
3486 // by linker scripts.
3487 std::stable_sort(this->segment_list_.begin(), this->segment_list_.end(),
3488 Layout::Compare_segments(this));
3489
3490 // Find the PT_LOAD segments, and set their addresses and offsets
3491 // and their section's addresses and offsets.
3492 uint64_t start_addr;
3493 if (parameters->options().user_set_Ttext())
3494 start_addr = parameters->options().Ttext();
3495 else if (parameters->options().output_is_position_independent())
3496 start_addr = 0;
3497 else
3498 start_addr = target->default_text_segment_address();
3499
3500 uint64_t addr = start_addr;
3501 off_t off = 0;
3502
3503 // If LOAD_SEG is NULL, then the file header and segment headers
3504 // will not be loadable. But they still need to be at offset 0 in
3505 // the file. Set their offsets now.
3506 if (load_seg == NULL)
3507 {
3508 for (Data_list::iterator p = this->special_output_list_.begin();
3509 p != this->special_output_list_.end();
3510 ++p)
3511 {
3512 off = align_address(off, (*p)->addralign());
3513 (*p)->set_address_and_file_offset(0, off);
3514 off += (*p)->data_size();
3515 }
3516 }
3517
3518 unsigned int increase_relro = this->increase_relro_;
3519 if (this->script_options_->saw_sections_clause())
3520 increase_relro = 0;
3521
3522 const bool check_sections = parameters->options().check_sections();
3523 Output_segment* last_load_segment = NULL;
3524
3525 unsigned int shndx_begin = *pshndx;
3526 unsigned int shndx_load_seg = *pshndx;
3527
3528 for (Segment_list::iterator p = this->segment_list_.begin();
3529 p != this->segment_list_.end();
3530 ++p)
3531 {
3532 if ((*p)->type() == elfcpp::PT_LOAD)
3533 {
3534 if (target->isolate_execinstr())
3535 {
3536 // When we hit the segment that should contain the
3537 // file headers, reset the file offset so we place
3538 // it and subsequent segments appropriately.
3539 // We'll fix up the preceding segments below.
3540 if (load_seg == *p)
3541 {
3542 if (off == 0)
3543 load_seg = NULL;
3544 else
3545 {
3546 off = 0;
3547 shndx_load_seg = *pshndx;
3548 }
3549 }
3550 }
3551 else
3552 {
3553 // Verify that the file headers fall into the first segment.
3554 if (load_seg != NULL && load_seg != *p)
3555 gold_unreachable();
3556 load_seg = NULL;
3557 }
3558
3559 bool are_addresses_set = (*p)->are_addresses_set();
3560 if (are_addresses_set)
3561 {
3562 // When it comes to setting file offsets, we care about
3563 // the physical address.
3564 addr = (*p)->paddr();
3565 }
3566 else if (parameters->options().user_set_Ttext()
3567 && (parameters->options().omagic()
3568 || is_text_segment(target, *p)))
3569 {
3570 are_addresses_set = true;
3571 }
3572 else if (parameters->options().user_set_Trodata_segment()
3573 && ((*p)->flags() & (elfcpp::PF_W | elfcpp::PF_X)) == 0)
3574 {
3575 addr = parameters->options().Trodata_segment();
3576 are_addresses_set = true;
3577 }
3578 else if (parameters->options().user_set_Tdata()
3579 && ((*p)->flags() & elfcpp::PF_W) != 0
3580 && (!parameters->options().user_set_Tbss()
3581 || (*p)->has_any_data_sections()))
3582 {
3583 addr = parameters->options().Tdata();
3584 are_addresses_set = true;
3585 }
3586 else if (parameters->options().user_set_Tbss()
3587 && ((*p)->flags() & elfcpp::PF_W) != 0
3588 && !(*p)->has_any_data_sections())
3589 {
3590 addr = parameters->options().Tbss();
3591 are_addresses_set = true;
3592 }
3593
3594 uint64_t orig_addr = addr;
3595 uint64_t orig_off = off;
3596
3597 uint64_t aligned_addr = 0;
3598 uint64_t abi_pagesize = target->abi_pagesize();
3599 uint64_t common_pagesize = target->common_pagesize();
3600
3601 if (!parameters->options().nmagic()
3602 && !parameters->options().omagic())
3603 (*p)->set_minimum_p_align(abi_pagesize);
3604
3605 if (!are_addresses_set)
3606 {
3607 // Skip the address forward one page, maintaining the same
3608 // position within the page. This lets us store both segments
3609 // overlapping on a single page in the file, but the loader will
3610 // put them on different pages in memory. We will revisit this
3611 // decision once we know the size of the segment.
3612
3613 uint64_t max_align = (*p)->maximum_alignment();
3614 if (max_align > abi_pagesize)
3615 addr = align_address(addr, max_align);
3616 aligned_addr = addr;
3617
3618 if (load_seg == *p)
3619 {
3620 // This is the segment that will contain the file
3621 // headers, so its offset will have to be exactly zero.
3622 gold_assert(orig_off == 0);
3623
3624 // If the target wants a fixed minimum distance from the
3625 // text segment to the read-only segment, move up now.
3626 uint64_t min_addr =
3627 start_addr + (parameters->options().user_set_rosegment_gap()
3628 ? parameters->options().rosegment_gap()
3629 : target->rosegment_gap());
3630 if (addr < min_addr)
3631 addr = min_addr;
3632
3633 // But this is not the first segment! To make its
3634 // address congruent with its offset, that address better
3635 // be aligned to the ABI-mandated page size.
3636 addr = align_address(addr, abi_pagesize);
3637 aligned_addr = addr;
3638 }
3639 else
3640 {
3641 if ((addr & (abi_pagesize - 1)) != 0)
3642 addr = addr + abi_pagesize;
3643
3644 off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
3645 }
3646 }
3647
3648 if (!parameters->options().nmagic()
3649 && !parameters->options().omagic())
3650 {
3651 // Here we are also taking care of the case when
3652 // the maximum segment alignment is larger than the page size.
3653 off = align_file_offset(off, addr,
3654 std::max(abi_pagesize,
3655 (*p)->maximum_alignment()));
3656 }
3657 else
3658 {
3659 // This is -N or -n with a section script which prevents
3660 // us from using a load segment. We need to ensure that
3661 // the file offset is aligned to the alignment of the
3662 // segment. This is because the linker script
3663 // implicitly assumed a zero offset. If we don't align
3664 // here, then the alignment of the sections in the
3665 // linker script may not match the alignment of the
3666 // sections in the set_section_addresses call below,
3667 // causing an error about dot moving backward.
3668 off = align_address(off, (*p)->maximum_alignment());
3669 }
3670
3671 unsigned int shndx_hold = *pshndx;
3672 bool has_relro = false;
3673 uint64_t new_addr = (*p)->set_section_addresses(target, this,
3674 false, addr,
3675 &increase_relro,
3676 &has_relro,
3677 &off, pshndx);
3678
3679 // Now that we know the size of this segment, we may be able
3680 // to save a page in memory, at the cost of wasting some
3681 // file space, by instead aligning to the start of a new
3682 // page. Here we use the real machine page size rather than
3683 // the ABI mandated page size. If the segment has been
3684 // aligned so that the relro data ends at a page boundary,
3685 // we do not try to realign it.
3686
3687 if (!are_addresses_set
3688 && !has_relro
3689 && aligned_addr != addr
3690 && !parameters->incremental())
3691 {
3692 uint64_t first_off = (common_pagesize
3693 - (aligned_addr
3694 & (common_pagesize - 1)));
3695 uint64_t last_off = new_addr & (common_pagesize - 1);
3696 if (first_off > 0
3697 && last_off > 0
3698 && ((aligned_addr & ~ (common_pagesize - 1))
3699 != (new_addr & ~ (common_pagesize - 1)))
3700 && first_off + last_off <= common_pagesize)
3701 {
3702 *pshndx = shndx_hold;
3703 addr = align_address(aligned_addr, common_pagesize);
3704 addr = align_address(addr, (*p)->maximum_alignment());
3705 if ((addr & (abi_pagesize - 1)) != 0)
3706 addr = addr + abi_pagesize;
3707 off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
3708 off = align_file_offset(off, addr, abi_pagesize);
3709
3710 increase_relro = this->increase_relro_;
3711 if (this->script_options_->saw_sections_clause())
3712 increase_relro = 0;
3713 has_relro = false;
3714
3715 new_addr = (*p)->set_section_addresses(target, this,
3716 true, addr,
3717 &increase_relro,
3718 &has_relro,
3719 &off, pshndx);
3720 }
3721 }
3722
3723 addr = new_addr;
3724
3725 // Implement --check-sections. We know that the segments
3726 // are sorted by LMA.
3727 if (check_sections && last_load_segment != NULL)
3728 {
3729 gold_assert(last_load_segment->paddr() <= (*p)->paddr());
3730 if (last_load_segment->paddr() + last_load_segment->memsz()
3731 > (*p)->paddr())
3732 {
3733 unsigned long long lb1 = last_load_segment->paddr();
3734 unsigned long long le1 = lb1 + last_load_segment->memsz();
3735 unsigned long long lb2 = (*p)->paddr();
3736 unsigned long long le2 = lb2 + (*p)->memsz();
3737 gold_error(_("load segment overlap [0x%llx -> 0x%llx] and "
3738 "[0x%llx -> 0x%llx]"),
3739 lb1, le1, lb2, le2);
3740 }
3741 }
3742 last_load_segment = *p;
3743 }
3744 }
3745
3746 if (load_seg != NULL && target->isolate_execinstr())
3747 {
3748 // Process the early segments again, setting their file offsets
3749 // so they land after the segments starting at LOAD_SEG.
3750 off = align_file_offset(off, 0, target->abi_pagesize());
3751
3752 this->reset_relax_output();
3753
3754 for (Segment_list::iterator p = this->segment_list_.begin();
3755 *p != load_seg;
3756 ++p)
3757 {
3758 if ((*p)->type() == elfcpp::PT_LOAD)
3759 {
3760 // We repeat the whole job of assigning addresses and
3761 // offsets, but we really only want to change the offsets and
3762 // must ensure that the addresses all come out the same as
3763 // they did the first time through.
3764 bool has_relro = false;
3765 const uint64_t old_addr = (*p)->vaddr();
3766 const uint64_t old_end = old_addr + (*p)->memsz();
3767 uint64_t new_addr = (*p)->set_section_addresses(target, this,
3768 true, old_addr,
3769 &increase_relro,
3770 &has_relro,
3771 &off,
3772 &shndx_begin);
3773 gold_assert(new_addr == old_end);
3774 }
3775 }
3776
3777 gold_assert(shndx_begin == shndx_load_seg);
3778 }
3779
3780 // Handle the non-PT_LOAD segments, setting their offsets from their
3781 // section's offsets.
3782 for (Segment_list::iterator p = this->segment_list_.begin();
3783 p != this->segment_list_.end();
3784 ++p)
3785 {
3786 // PT_GNU_STACK was set up correctly when it was created.
3787 if ((*p)->type() != elfcpp::PT_LOAD
3788 && (*p)->type() != elfcpp::PT_GNU_STACK)
3789 (*p)->set_offset((*p)->type() == elfcpp::PT_GNU_RELRO
3790 ? increase_relro
3791 : 0);
3792 }
3793
3794 // Set the TLS offsets for each section in the PT_TLS segment.
3795 if (this->tls_segment_ != NULL)
3796 this->tls_segment_->set_tls_offsets();
3797
3798 return off;
3799 }
3800
3801 // Set the offsets of all the allocated sections when doing a
3802 // relocatable link. This does the same jobs as set_segment_offsets,
3803 // only for a relocatable link.
3804
3805 off_t
set_relocatable_section_offsets(Output_data * file_header,unsigned int * pshndx)3806 Layout::set_relocatable_section_offsets(Output_data* file_header,
3807 unsigned int* pshndx)
3808 {
3809 off_t off = 0;
3810
3811 file_header->set_address_and_file_offset(0, 0);
3812 off += file_header->data_size();
3813
3814 for (Section_list::iterator p = this->section_list_.begin();
3815 p != this->section_list_.end();
3816 ++p)
3817 {
3818 // We skip unallocated sections here, except that group sections
3819 // have to come first.
3820 if (((*p)->flags() & elfcpp::SHF_ALLOC) == 0
3821 && (*p)->type() != elfcpp::SHT_GROUP)
3822 continue;
3823
3824 off = align_address(off, (*p)->addralign());
3825
3826 // The linker script might have set the address.
3827 if (!(*p)->is_address_valid())
3828 (*p)->set_address(0);
3829 (*p)->set_file_offset(off);
3830 (*p)->finalize_data_size();
3831 if ((*p)->type() != elfcpp::SHT_NOBITS)
3832 off += (*p)->data_size();
3833
3834 (*p)->set_out_shndx(*pshndx);
3835 ++*pshndx;
3836 }
3837
3838 return off;
3839 }
3840
3841 // Set the file offset of all the sections not associated with a
3842 // segment.
3843
3844 off_t
set_section_offsets(off_t off,Layout::Section_offset_pass pass)3845 Layout::set_section_offsets(off_t off, Layout::Section_offset_pass pass)
3846 {
3847 off_t startoff = off;
3848 off_t maxoff = off;
3849
3850 for (Section_list::iterator p = this->unattached_section_list_.begin();
3851 p != this->unattached_section_list_.end();
3852 ++p)
3853 {
3854 // The symtab section is handled in create_symtab_sections.
3855 if (*p == this->symtab_section_)
3856 continue;
3857
3858 // If we've already set the data size, don't set it again.
3859 if ((*p)->is_offset_valid() && (*p)->is_data_size_valid())
3860 continue;
3861
3862 if (pass == BEFORE_INPUT_SECTIONS_PASS
3863 && (*p)->requires_postprocessing())
3864 {
3865 (*p)->create_postprocessing_buffer();
3866 this->any_postprocessing_sections_ = true;
3867 }
3868
3869 if (pass == BEFORE_INPUT_SECTIONS_PASS
3870 && (*p)->after_input_sections())
3871 continue;
3872 else if (pass == POSTPROCESSING_SECTIONS_PASS
3873 && (!(*p)->after_input_sections()
3874 || (*p)->type() == elfcpp::SHT_STRTAB))
3875 continue;
3876 else if (pass == STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
3877 && (!(*p)->after_input_sections()
3878 || (*p)->type() != elfcpp::SHT_STRTAB))
3879 continue;
3880
3881 if (!parameters->incremental_update())
3882 {
3883 off = align_address(off, (*p)->addralign());
3884 (*p)->set_file_offset(off);
3885 (*p)->finalize_data_size();
3886 }
3887 else
3888 {
3889 // Incremental update: allocate file space from free list.
3890 (*p)->pre_finalize_data_size();
3891 off_t current_size = (*p)->current_data_size();
3892 off = this->allocate(current_size, (*p)->addralign(), startoff);
3893 if (off == -1)
3894 {
3895 if (is_debugging_enabled(DEBUG_INCREMENTAL))
3896 this->free_list_.dump();
3897 gold_assert((*p)->output_section() != NULL);
3898 gold_fallback(_("out of patch space for section %s; "
3899 "relink with --incremental-full"),
3900 (*p)->output_section()->name());
3901 }
3902 (*p)->set_file_offset(off);
3903 (*p)->finalize_data_size();
3904 if ((*p)->data_size() > current_size)
3905 {
3906 gold_assert((*p)->output_section() != NULL);
3907 gold_fallback(_("%s: section changed size; "
3908 "relink with --incremental-full"),
3909 (*p)->output_section()->name());
3910 }
3911 gold_debug(DEBUG_INCREMENTAL,
3912 "set_section_offsets: %08lx %08lx %s",
3913 static_cast<long>(off),
3914 static_cast<long>((*p)->data_size()),
3915 ((*p)->output_section() != NULL
3916 ? (*p)->output_section()->name() : "(special)"));
3917 }
3918
3919 off += (*p)->data_size();
3920 if (off > maxoff)
3921 maxoff = off;
3922
3923 // At this point the name must be set.
3924 if (pass != STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS)
3925 this->namepool_.add((*p)->name(), false, NULL);
3926 }
3927 return maxoff;
3928 }
3929
3930 // Set the section indexes of all the sections not associated with a
3931 // segment.
3932
3933 unsigned int
set_section_indexes(unsigned int shndx)3934 Layout::set_section_indexes(unsigned int shndx)
3935 {
3936 for (Section_list::iterator p = this->unattached_section_list_.begin();
3937 p != this->unattached_section_list_.end();
3938 ++p)
3939 {
3940 if (!(*p)->has_out_shndx())
3941 {
3942 (*p)->set_out_shndx(shndx);
3943 ++shndx;
3944 }
3945 }
3946 return shndx;
3947 }
3948
3949 // Set the section addresses according to the linker script. This is
3950 // only called when we see a SECTIONS clause. This returns the
3951 // program segment which should hold the file header and segment
3952 // headers, if any. It will return NULL if they should not be in a
3953 // segment.
3954
3955 Output_segment*
set_section_addresses_from_script(Symbol_table * symtab)3956 Layout::set_section_addresses_from_script(Symbol_table* symtab)
3957 {
3958 Script_sections* ss = this->script_options_->script_sections();
3959 gold_assert(ss->saw_sections_clause());
3960 return this->script_options_->set_section_addresses(symtab, this);
3961 }
3962
3963 // Place the orphan sections in the linker script.
3964
3965 void
place_orphan_sections_in_script()3966 Layout::place_orphan_sections_in_script()
3967 {
3968 Script_sections* ss = this->script_options_->script_sections();
3969 gold_assert(ss->saw_sections_clause());
3970
3971 // Place each orphaned output section in the script.
3972 for (Section_list::iterator p = this->section_list_.begin();
3973 p != this->section_list_.end();
3974 ++p)
3975 {
3976 if (!(*p)->found_in_sections_clause())
3977 ss->place_orphan(*p);
3978 }
3979 }
3980
3981 // Count the local symbols in the regular symbol table and the dynamic
3982 // symbol table, and build the respective string pools.
3983
3984 void
count_local_symbols(const Task * task,const Input_objects * input_objects)3985 Layout::count_local_symbols(const Task* task,
3986 const Input_objects* input_objects)
3987 {
3988 // First, figure out an upper bound on the number of symbols we'll
3989 // be inserting into each pool. This helps us create the pools with
3990 // the right size, to avoid unnecessary hashtable resizing.
3991 unsigned int symbol_count = 0;
3992 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
3993 p != input_objects->relobj_end();
3994 ++p)
3995 symbol_count += (*p)->local_symbol_count();
3996
3997 // Go from "upper bound" to "estimate." We overcount for two
3998 // reasons: we double-count symbols that occur in more than one
3999 // object file, and we count symbols that are dropped from the
4000 // output. Add it all together and assume we overcount by 100%.
4001 symbol_count /= 2;
4002
4003 // We assume all symbols will go into both the sympool and dynpool.
4004 this->sympool_.reserve(symbol_count);
4005 this->dynpool_.reserve(symbol_count);
4006
4007 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
4008 p != input_objects->relobj_end();
4009 ++p)
4010 {
4011 Task_lock_obj<Object> tlo(task, *p);
4012 (*p)->count_local_symbols(&this->sympool_, &this->dynpool_);
4013 }
4014 }
4015
4016 // Create the symbol table sections. Here we also set the final
4017 // values of the symbols. At this point all the loadable sections are
4018 // fully laid out. SHNUM is the number of sections so far.
4019
4020 void
create_symtab_sections(const Input_objects * input_objects,Symbol_table * symtab,unsigned int shnum,off_t * poff)4021 Layout::create_symtab_sections(const Input_objects* input_objects,
4022 Symbol_table* symtab,
4023 unsigned int shnum,
4024 off_t* poff)
4025 {
4026 int symsize;
4027 unsigned int align;
4028 if (parameters->target().get_size() == 32)
4029 {
4030 symsize = elfcpp::Elf_sizes<32>::sym_size;
4031 align = 4;
4032 }
4033 else if (parameters->target().get_size() == 64)
4034 {
4035 symsize = elfcpp::Elf_sizes<64>::sym_size;
4036 align = 8;
4037 }
4038 else
4039 gold_unreachable();
4040
4041 // Compute file offsets relative to the start of the symtab section.
4042 off_t off = 0;
4043
4044 // Save space for the dummy symbol at the start of the section. We
4045 // never bother to write this out--it will just be left as zero.
4046 off += symsize;
4047 unsigned int local_symbol_index = 1;
4048
4049 // Add STT_SECTION symbols for each Output section which needs one.
4050 for (Section_list::iterator p = this->section_list_.begin();
4051 p != this->section_list_.end();
4052 ++p)
4053 {
4054 if (!(*p)->needs_symtab_index())
4055 (*p)->set_symtab_index(-1U);
4056 else
4057 {
4058 (*p)->set_symtab_index(local_symbol_index);
4059 ++local_symbol_index;
4060 off += symsize;
4061 }
4062 }
4063
4064 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
4065 p != input_objects->relobj_end();
4066 ++p)
4067 {
4068 unsigned int index = (*p)->finalize_local_symbols(local_symbol_index,
4069 off, symtab);
4070 off += (index - local_symbol_index) * symsize;
4071 local_symbol_index = index;
4072 }
4073
4074 unsigned int local_symcount = local_symbol_index;
4075 gold_assert(static_cast<off_t>(local_symcount * symsize) == off);
4076
4077 off_t dynoff;
4078 size_t dyn_global_index;
4079 size_t dyncount;
4080 if (this->dynsym_section_ == NULL)
4081 {
4082 dynoff = 0;
4083 dyn_global_index = 0;
4084 dyncount = 0;
4085 }
4086 else
4087 {
4088 dyn_global_index = this->dynsym_section_->info();
4089 off_t locsize = dyn_global_index * this->dynsym_section_->entsize();
4090 dynoff = this->dynsym_section_->offset() + locsize;
4091 dyncount = (this->dynsym_section_->data_size() - locsize) / symsize;
4092 gold_assert(static_cast<off_t>(dyncount * symsize)
4093 == this->dynsym_section_->data_size() - locsize);
4094 }
4095
4096 off_t global_off = off;
4097 off = symtab->finalize(off, dynoff, dyn_global_index, dyncount,
4098 &this->sympool_, &local_symcount);
4099
4100 if (!parameters->options().strip_all())
4101 {
4102 this->sympool_.set_string_offsets();
4103
4104 const char* symtab_name = this->namepool_.add(".symtab", false, NULL);
4105 Output_section* osymtab = this->make_output_section(symtab_name,
4106 elfcpp::SHT_SYMTAB,
4107 0, ORDER_INVALID,
4108 false);
4109 this->symtab_section_ = osymtab;
4110
4111 Output_section_data* pos = new Output_data_fixed_space(off, align,
4112 "** symtab");
4113 osymtab->add_output_section_data(pos);
4114
4115 // We generate a .symtab_shndx section if we have more than
4116 // SHN_LORESERVE sections. Technically it is possible that we
4117 // don't need one, because it is possible that there are no
4118 // symbols in any of sections with indexes larger than
4119 // SHN_LORESERVE. That is probably unusual, though, and it is
4120 // easier to always create one than to compute section indexes
4121 // twice (once here, once when writing out the symbols).
4122 if (shnum >= elfcpp::SHN_LORESERVE)
4123 {
4124 const char* symtab_xindex_name = this->namepool_.add(".symtab_shndx",
4125 false, NULL);
4126 Output_section* osymtab_xindex =
4127 this->make_output_section(symtab_xindex_name,
4128 elfcpp::SHT_SYMTAB_SHNDX, 0,
4129 ORDER_INVALID, false);
4130
4131 size_t symcount = off / symsize;
4132 this->symtab_xindex_ = new Output_symtab_xindex(symcount);
4133
4134 osymtab_xindex->add_output_section_data(this->symtab_xindex_);
4135
4136 osymtab_xindex->set_link_section(osymtab);
4137 osymtab_xindex->set_addralign(4);
4138 osymtab_xindex->set_entsize(4);
4139
4140 osymtab_xindex->set_after_input_sections();
4141
4142 // This tells the driver code to wait until the symbol table
4143 // has written out before writing out the postprocessing
4144 // sections, including the .symtab_shndx section.
4145 this->any_postprocessing_sections_ = true;
4146 }
4147
4148 const char* strtab_name = this->namepool_.add(".strtab", false, NULL);
4149 Output_section* ostrtab = this->make_output_section(strtab_name,
4150 elfcpp::SHT_STRTAB,
4151 0, ORDER_INVALID,
4152 false);
4153
4154 Output_section_data* pstr = new Output_data_strtab(&this->sympool_);
4155 ostrtab->add_output_section_data(pstr);
4156
4157 off_t symtab_off;
4158 if (!parameters->incremental_update())
4159 symtab_off = align_address(*poff, align);
4160 else
4161 {
4162 symtab_off = this->allocate(off, align, *poff);
4163 if (off == -1)
4164 gold_fallback(_("out of patch space for symbol table; "
4165 "relink with --incremental-full"));
4166 gold_debug(DEBUG_INCREMENTAL,
4167 "create_symtab_sections: %08lx %08lx .symtab",
4168 static_cast<long>(symtab_off),
4169 static_cast<long>(off));
4170 }
4171
4172 symtab->set_file_offset(symtab_off + global_off);
4173 osymtab->set_file_offset(symtab_off);
4174 osymtab->finalize_data_size();
4175 osymtab->set_link_section(ostrtab);
4176 osymtab->set_info(local_symcount);
4177 osymtab->set_entsize(symsize);
4178
4179 if (symtab_off + off > *poff)
4180 *poff = symtab_off + off;
4181 }
4182 }
4183
4184 // Create the .shstrtab section, which holds the names of the
4185 // sections. At the time this is called, we have created all the
4186 // output sections except .shstrtab itself.
4187
4188 Output_section*
create_shstrtab()4189 Layout::create_shstrtab()
4190 {
4191 // FIXME: We don't need to create a .shstrtab section if we are
4192 // stripping everything.
4193
4194 const char* name = this->namepool_.add(".shstrtab", false, NULL);
4195
4196 Output_section* os = this->make_output_section(name, elfcpp::SHT_STRTAB, 0,
4197 ORDER_INVALID, false);
4198
4199 if (strcmp(parameters->options().compress_debug_sections(), "none") != 0)
4200 {
4201 // We can't write out this section until we've set all the
4202 // section names, and we don't set the names of compressed
4203 // output sections until relocations are complete. FIXME: With
4204 // the current names we use, this is unnecessary.
4205 os->set_after_input_sections();
4206 }
4207
4208 Output_section_data* posd = new Output_data_strtab(&this->namepool_);
4209 os->add_output_section_data(posd);
4210
4211 return os;
4212 }
4213
4214 // Create the section headers. SIZE is 32 or 64. OFF is the file
4215 // offset.
4216
4217 void
create_shdrs(const Output_section * shstrtab_section,off_t * poff)4218 Layout::create_shdrs(const Output_section* shstrtab_section, off_t* poff)
4219 {
4220 Output_section_headers* oshdrs;
4221 oshdrs = new Output_section_headers(this,
4222 &this->segment_list_,
4223 &this->section_list_,
4224 &this->unattached_section_list_,
4225 &this->namepool_,
4226 shstrtab_section);
4227 off_t off;
4228 if (!parameters->incremental_update())
4229 off = align_address(*poff, oshdrs->addralign());
4230 else
4231 {
4232 oshdrs->pre_finalize_data_size();
4233 off = this->allocate(oshdrs->data_size(), oshdrs->addralign(), *poff);
4234 if (off == -1)
4235 gold_fallback(_("out of patch space for section header table; "
4236 "relink with --incremental-full"));
4237 gold_debug(DEBUG_INCREMENTAL,
4238 "create_shdrs: %08lx %08lx (section header table)",
4239 static_cast<long>(off),
4240 static_cast<long>(off + oshdrs->data_size()));
4241 }
4242 oshdrs->set_address_and_file_offset(0, off);
4243 off += oshdrs->data_size();
4244 if (off > *poff)
4245 *poff = off;
4246 this->section_headers_ = oshdrs;
4247 }
4248
4249 // Count the allocated sections.
4250
4251 size_t
allocated_output_section_count() const4252 Layout::allocated_output_section_count() const
4253 {
4254 size_t section_count = 0;
4255 for (Segment_list::const_iterator p = this->segment_list_.begin();
4256 p != this->segment_list_.end();
4257 ++p)
4258 section_count += (*p)->output_section_count();
4259 return section_count;
4260 }
4261
4262 // Create the dynamic symbol table.
4263
4264 void
create_dynamic_symtab(const Input_objects * input_objects,Symbol_table * symtab,Output_section ** pdynstr,unsigned int * plocal_dynamic_count,std::vector<Symbol * > * pdynamic_symbols,Versions * pversions)4265 Layout::create_dynamic_symtab(const Input_objects* input_objects,
4266 Symbol_table* symtab,
4267 Output_section** pdynstr,
4268 unsigned int* plocal_dynamic_count,
4269 std::vector<Symbol*>* pdynamic_symbols,
4270 Versions* pversions)
4271 {
4272 // Count all the symbols in the dynamic symbol table, and set the
4273 // dynamic symbol indexes.
4274
4275 // Skip symbol 0, which is always all zeroes.
4276 unsigned int index = 1;
4277
4278 // Add STT_SECTION symbols for each Output section which needs one.
4279 for (Section_list::iterator p = this->section_list_.begin();
4280 p != this->section_list_.end();
4281 ++p)
4282 {
4283 if (!(*p)->needs_dynsym_index())
4284 (*p)->set_dynsym_index(-1U);
4285 else
4286 {
4287 (*p)->set_dynsym_index(index);
4288 ++index;
4289 }
4290 }
4291
4292 // Count the local symbols that need to go in the dynamic symbol table,
4293 // and set the dynamic symbol indexes.
4294 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
4295 p != input_objects->relobj_end();
4296 ++p)
4297 {
4298 unsigned int new_index = (*p)->set_local_dynsym_indexes(index);
4299 index = new_index;
4300 }
4301
4302 unsigned int local_symcount = index;
4303 *plocal_dynamic_count = local_symcount;
4304
4305 index = symtab->set_dynsym_indexes(index, pdynamic_symbols,
4306 &this->dynpool_, pversions);
4307
4308 int symsize;
4309 unsigned int align;
4310 const int size = parameters->target().get_size();
4311 if (size == 32)
4312 {
4313 symsize = elfcpp::Elf_sizes<32>::sym_size;
4314 align = 4;
4315 }
4316 else if (size == 64)
4317 {
4318 symsize = elfcpp::Elf_sizes<64>::sym_size;
4319 align = 8;
4320 }
4321 else
4322 gold_unreachable();
4323
4324 // Create the dynamic symbol table section.
4325
4326 Output_section* dynsym = this->choose_output_section(NULL, ".dynsym",
4327 elfcpp::SHT_DYNSYM,
4328 elfcpp::SHF_ALLOC,
4329 false,
4330 ORDER_DYNAMIC_LINKER,
4331 false);
4332
4333 // Check for NULL as a linker script may discard .dynsym.
4334 if (dynsym != NULL)
4335 {
4336 Output_section_data* odata = new Output_data_fixed_space(index * symsize,
4337 align,
4338 "** dynsym");
4339 dynsym->add_output_section_data(odata);
4340
4341 dynsym->set_info(local_symcount);
4342 dynsym->set_entsize(symsize);
4343 dynsym->set_addralign(align);
4344
4345 this->dynsym_section_ = dynsym;
4346 }
4347
4348 Output_data_dynamic* const odyn = this->dynamic_data_;
4349 if (odyn != NULL)
4350 {
4351 odyn->add_section_address(elfcpp::DT_SYMTAB, dynsym);
4352 odyn->add_constant(elfcpp::DT_SYMENT, symsize);
4353 }
4354
4355 // If there are more than SHN_LORESERVE allocated sections, we
4356 // create a .dynsym_shndx section. It is possible that we don't
4357 // need one, because it is possible that there are no dynamic
4358 // symbols in any of the sections with indexes larger than
4359 // SHN_LORESERVE. This is probably unusual, though, and at this
4360 // time we don't know the actual section indexes so it is
4361 // inconvenient to check.
4362 if (this->allocated_output_section_count() >= elfcpp::SHN_LORESERVE)
4363 {
4364 Output_section* dynsym_xindex =
4365 this->choose_output_section(NULL, ".dynsym_shndx",
4366 elfcpp::SHT_SYMTAB_SHNDX,
4367 elfcpp::SHF_ALLOC,
4368 false, ORDER_DYNAMIC_LINKER, false);
4369
4370 if (dynsym_xindex != NULL)
4371 {
4372 this->dynsym_xindex_ = new Output_symtab_xindex(index);
4373
4374 dynsym_xindex->add_output_section_data(this->dynsym_xindex_);
4375
4376 dynsym_xindex->set_link_section(dynsym);
4377 dynsym_xindex->set_addralign(4);
4378 dynsym_xindex->set_entsize(4);
4379
4380 dynsym_xindex->set_after_input_sections();
4381
4382 // This tells the driver code to wait until the symbol table
4383 // has written out before writing out the postprocessing
4384 // sections, including the .dynsym_shndx section.
4385 this->any_postprocessing_sections_ = true;
4386 }
4387 }
4388
4389 // Create the dynamic string table section.
4390
4391 Output_section* dynstr = this->choose_output_section(NULL, ".dynstr",
4392 elfcpp::SHT_STRTAB,
4393 elfcpp::SHF_ALLOC,
4394 false,
4395 ORDER_DYNAMIC_LINKER,
4396 false);
4397 *pdynstr = dynstr;
4398 if (dynstr != NULL)
4399 {
4400 Output_section_data* strdata = new Output_data_strtab(&this->dynpool_);
4401 dynstr->add_output_section_data(strdata);
4402
4403 if (dynsym != NULL)
4404 dynsym->set_link_section(dynstr);
4405 if (this->dynamic_section_ != NULL)
4406 this->dynamic_section_->set_link_section(dynstr);
4407
4408 if (odyn != NULL)
4409 {
4410 odyn->add_section_address(elfcpp::DT_STRTAB, dynstr);
4411 odyn->add_section_size(elfcpp::DT_STRSZ, dynstr);
4412 }
4413 }
4414
4415 // Create the hash tables. The Gnu-style hash table must be
4416 // built first, because it changes the order of the symbols
4417 // in the dynamic symbol table.
4418
4419 if (strcmp(parameters->options().hash_style(), "gnu") == 0
4420 || strcmp(parameters->options().hash_style(), "both") == 0)
4421 {
4422 unsigned char* phash;
4423 unsigned int hashlen;
4424 Dynobj::create_gnu_hash_table(*pdynamic_symbols, local_symcount,
4425 &phash, &hashlen);
4426
4427 Output_section* hashsec =
4428 this->choose_output_section(NULL, ".gnu.hash", elfcpp::SHT_GNU_HASH,
4429 elfcpp::SHF_ALLOC, false,
4430 ORDER_DYNAMIC_LINKER, false);
4431
4432 Output_section_data* hashdata = new Output_data_const_buffer(phash,
4433 hashlen,
4434 align,
4435 "** hash");
4436 if (hashsec != NULL && hashdata != NULL)
4437 hashsec->add_output_section_data(hashdata);
4438
4439 if (hashsec != NULL)
4440 {
4441 if (dynsym != NULL)
4442 hashsec->set_link_section(dynsym);
4443
4444 // For a 64-bit target, the entries in .gnu.hash do not have
4445 // a uniform size, so we only set the entry size for a
4446 // 32-bit target.
4447 if (parameters->target().get_size() == 32)
4448 hashsec->set_entsize(4);
4449
4450 if (odyn != NULL)
4451 odyn->add_section_address(elfcpp::DT_GNU_HASH, hashsec);
4452 }
4453 }
4454
4455 if (strcmp(parameters->options().hash_style(), "sysv") == 0
4456 || strcmp(parameters->options().hash_style(), "both") == 0)
4457 {
4458 unsigned char* phash;
4459 unsigned int hashlen;
4460 Dynobj::create_elf_hash_table(*pdynamic_symbols, local_symcount,
4461 &phash, &hashlen);
4462
4463 Output_section* hashsec =
4464 this->choose_output_section(NULL, ".hash", elfcpp::SHT_HASH,
4465 elfcpp::SHF_ALLOC, false,
4466 ORDER_DYNAMIC_LINKER, false);
4467
4468 Output_section_data* hashdata = new Output_data_const_buffer(phash,
4469 hashlen,
4470 align,
4471 "** hash");
4472 if (hashsec != NULL && hashdata != NULL)
4473 hashsec->add_output_section_data(hashdata);
4474
4475 if (hashsec != NULL)
4476 {
4477 if (dynsym != NULL)
4478 hashsec->set_link_section(dynsym);
4479 hashsec->set_entsize(parameters->target().hash_entry_size() / 8);
4480 }
4481
4482 if (odyn != NULL)
4483 odyn->add_section_address(elfcpp::DT_HASH, hashsec);
4484 }
4485 }
4486
4487 // Assign offsets to each local portion of the dynamic symbol table.
4488
4489 void
assign_local_dynsym_offsets(const Input_objects * input_objects)4490 Layout::assign_local_dynsym_offsets(const Input_objects* input_objects)
4491 {
4492 Output_section* dynsym = this->dynsym_section_;
4493 if (dynsym == NULL)
4494 return;
4495
4496 off_t off = dynsym->offset();
4497
4498 // Skip the dummy symbol at the start of the section.
4499 off += dynsym->entsize();
4500
4501 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
4502 p != input_objects->relobj_end();
4503 ++p)
4504 {
4505 unsigned int count = (*p)->set_local_dynsym_offset(off);
4506 off += count * dynsym->entsize();
4507 }
4508 }
4509
4510 // Create the version sections.
4511
4512 void
create_version_sections(const Versions * versions,const Symbol_table * symtab,unsigned int local_symcount,const std::vector<Symbol * > & dynamic_symbols,const Output_section * dynstr)4513 Layout::create_version_sections(const Versions* versions,
4514 const Symbol_table* symtab,
4515 unsigned int local_symcount,
4516 const std::vector<Symbol*>& dynamic_symbols,
4517 const Output_section* dynstr)
4518 {
4519 if (!versions->any_defs() && !versions->any_needs())
4520 return;
4521
4522 switch (parameters->size_and_endianness())
4523 {
4524 #ifdef HAVE_TARGET_32_LITTLE
4525 case Parameters::TARGET_32_LITTLE:
4526 this->sized_create_version_sections<32, false>(versions, symtab,
4527 local_symcount,
4528 dynamic_symbols, dynstr);
4529 break;
4530 #endif
4531 #ifdef HAVE_TARGET_32_BIG
4532 case Parameters::TARGET_32_BIG:
4533 this->sized_create_version_sections<32, true>(versions, symtab,
4534 local_symcount,
4535 dynamic_symbols, dynstr);
4536 break;
4537 #endif
4538 #ifdef HAVE_TARGET_64_LITTLE
4539 case Parameters::TARGET_64_LITTLE:
4540 this->sized_create_version_sections<64, false>(versions, symtab,
4541 local_symcount,
4542 dynamic_symbols, dynstr);
4543 break;
4544 #endif
4545 #ifdef HAVE_TARGET_64_BIG
4546 case Parameters::TARGET_64_BIG:
4547 this->sized_create_version_sections<64, true>(versions, symtab,
4548 local_symcount,
4549 dynamic_symbols, dynstr);
4550 break;
4551 #endif
4552 default:
4553 gold_unreachable();
4554 }
4555 }
4556
4557 // Create the version sections, sized version.
4558
4559 template<int size, bool big_endian>
4560 void
sized_create_version_sections(const Versions * versions,const Symbol_table * symtab,unsigned int local_symcount,const std::vector<Symbol * > & dynamic_symbols,const Output_section * dynstr)4561 Layout::sized_create_version_sections(
4562 const Versions* versions,
4563 const Symbol_table* symtab,
4564 unsigned int local_symcount,
4565 const std::vector<Symbol*>& dynamic_symbols,
4566 const Output_section* dynstr)
4567 {
4568 Output_section* vsec = this->choose_output_section(NULL, ".gnu.version",
4569 elfcpp::SHT_GNU_versym,
4570 elfcpp::SHF_ALLOC,
4571 false,
4572 ORDER_DYNAMIC_LINKER,
4573 false);
4574
4575 // Check for NULL since a linker script may discard this section.
4576 if (vsec != NULL)
4577 {
4578 unsigned char* vbuf;
4579 unsigned int vsize;
4580 versions->symbol_section_contents<size, big_endian>(symtab,
4581 &this->dynpool_,
4582 local_symcount,
4583 dynamic_symbols,
4584 &vbuf, &vsize);
4585
4586 Output_section_data* vdata = new Output_data_const_buffer(vbuf, vsize, 2,
4587 "** versions");
4588
4589 vsec->add_output_section_data(vdata);
4590 vsec->set_entsize(2);
4591 vsec->set_link_section(this->dynsym_section_);
4592 }
4593
4594 Output_data_dynamic* const odyn = this->dynamic_data_;
4595 if (odyn != NULL && vsec != NULL)
4596 odyn->add_section_address(elfcpp::DT_VERSYM, vsec);
4597
4598 if (versions->any_defs())
4599 {
4600 Output_section* vdsec;
4601 vdsec = this->choose_output_section(NULL, ".gnu.version_d",
4602 elfcpp::SHT_GNU_verdef,
4603 elfcpp::SHF_ALLOC,
4604 false, ORDER_DYNAMIC_LINKER, false);
4605
4606 if (vdsec != NULL)
4607 {
4608 unsigned char* vdbuf;
4609 unsigned int vdsize;
4610 unsigned int vdentries;
4611 versions->def_section_contents<size, big_endian>(&this->dynpool_,
4612 &vdbuf, &vdsize,
4613 &vdentries);
4614
4615 Output_section_data* vddata =
4616 new Output_data_const_buffer(vdbuf, vdsize, 4, "** version defs");
4617
4618 vdsec->add_output_section_data(vddata);
4619 vdsec->set_link_section(dynstr);
4620 vdsec->set_info(vdentries);
4621
4622 if (odyn != NULL)
4623 {
4624 odyn->add_section_address(elfcpp::DT_VERDEF, vdsec);
4625 odyn->add_constant(elfcpp::DT_VERDEFNUM, vdentries);
4626 }
4627 }
4628 }
4629
4630 if (versions->any_needs())
4631 {
4632 Output_section* vnsec;
4633 vnsec = this->choose_output_section(NULL, ".gnu.version_r",
4634 elfcpp::SHT_GNU_verneed,
4635 elfcpp::SHF_ALLOC,
4636 false, ORDER_DYNAMIC_LINKER, false);
4637
4638 if (vnsec != NULL)
4639 {
4640 unsigned char* vnbuf;
4641 unsigned int vnsize;
4642 unsigned int vnentries;
4643 versions->need_section_contents<size, big_endian>(&this->dynpool_,
4644 &vnbuf, &vnsize,
4645 &vnentries);
4646
4647 Output_section_data* vndata =
4648 new Output_data_const_buffer(vnbuf, vnsize, 4, "** version refs");
4649
4650 vnsec->add_output_section_data(vndata);
4651 vnsec->set_link_section(dynstr);
4652 vnsec->set_info(vnentries);
4653
4654 if (odyn != NULL)
4655 {
4656 odyn->add_section_address(elfcpp::DT_VERNEED, vnsec);
4657 odyn->add_constant(elfcpp::DT_VERNEEDNUM, vnentries);
4658 }
4659 }
4660 }
4661 }
4662
4663 // Create the .interp section and PT_INTERP segment.
4664
4665 void
create_interp(const Target * target)4666 Layout::create_interp(const Target* target)
4667 {
4668 gold_assert(this->interp_segment_ == NULL);
4669
4670 const char* interp = parameters->options().dynamic_linker();
4671 if (interp == NULL)
4672 {
4673 interp = target->dynamic_linker();
4674 gold_assert(interp != NULL);
4675 }
4676
4677 size_t len = strlen(interp) + 1;
4678
4679 Output_section_data* odata = new Output_data_const(interp, len, 1);
4680
4681 Output_section* osec = this->choose_output_section(NULL, ".interp",
4682 elfcpp::SHT_PROGBITS,
4683 elfcpp::SHF_ALLOC,
4684 false, ORDER_INTERP,
4685 false);
4686 if (osec != NULL)
4687 osec->add_output_section_data(odata);
4688 }
4689
4690 // Add dynamic tags for the PLT and the dynamic relocs. This is
4691 // called by the target-specific code. This does nothing if not doing
4692 // a dynamic link.
4693
4694 // USE_REL is true for REL relocs rather than RELA relocs.
4695
4696 // If PLT_GOT is not NULL, then DT_PLTGOT points to it.
4697
4698 // If PLT_REL is not NULL, it is used for DT_PLTRELSZ, and DT_JMPREL,
4699 // and we also set DT_PLTREL. We use PLT_REL's output section, since
4700 // some targets have multiple reloc sections in PLT_REL.
4701
4702 // If DYN_REL is not NULL, it is used for DT_REL/DT_RELA,
4703 // DT_RELSZ/DT_RELASZ, DT_RELENT/DT_RELAENT. Again we use the output
4704 // section.
4705
4706 // If ADD_DEBUG is true, we add a DT_DEBUG entry when generating an
4707 // executable.
4708
4709 void
add_target_dynamic_tags(bool use_rel,const Output_data * plt_got,const Output_data * plt_rel,const Output_data_reloc_generic * dyn_rel,bool add_debug,bool dynrel_includes_plt,const Output_data_reloc_generic * dyn_relr)4710 Layout::add_target_dynamic_tags(bool use_rel, const Output_data* plt_got,
4711 const Output_data* plt_rel,
4712 const Output_data_reloc_generic* dyn_rel,
4713 bool add_debug, bool dynrel_includes_plt,
4714 const Output_data_reloc_generic* dyn_relr)
4715 {
4716 Output_data_dynamic* odyn = this->dynamic_data_;
4717 if (odyn == NULL)
4718 return;
4719
4720 if (plt_got != NULL && plt_got->output_section() != NULL)
4721 odyn->add_section_address(elfcpp::DT_PLTGOT, plt_got);
4722
4723 if (plt_rel != NULL && plt_rel->output_section() != NULL)
4724 {
4725 odyn->add_section_size(elfcpp::DT_PLTRELSZ, plt_rel->output_section());
4726 odyn->add_section_address(elfcpp::DT_JMPREL, plt_rel->output_section());
4727 odyn->add_constant(elfcpp::DT_PLTREL,
4728 use_rel ? elfcpp::DT_REL : elfcpp::DT_RELA);
4729 }
4730
4731 if ((dyn_rel != NULL && dyn_rel->output_section() != NULL)
4732 || (dynrel_includes_plt
4733 && plt_rel != NULL
4734 && plt_rel->output_section() != NULL))
4735 {
4736 bool have_dyn_rel = dyn_rel != NULL && dyn_rel->output_section() != NULL;
4737 bool have_plt_rel = plt_rel != NULL && plt_rel->output_section() != NULL;
4738 odyn->add_section_address(use_rel ? elfcpp::DT_REL : elfcpp::DT_RELA,
4739 (have_dyn_rel
4740 ? dyn_rel->output_section()
4741 : plt_rel->output_section()));
4742 elfcpp::DT size_tag = use_rel ? elfcpp::DT_RELSZ : elfcpp::DT_RELASZ;
4743 if (have_dyn_rel && have_plt_rel && dynrel_includes_plt)
4744 odyn->add_section_size(size_tag,
4745 dyn_rel->output_section(),
4746 plt_rel->output_section());
4747 else if (have_dyn_rel)
4748 odyn->add_section_size(size_tag, dyn_rel->output_section());
4749 else
4750 odyn->add_section_size(size_tag, plt_rel->output_section());
4751 const int size = parameters->target().get_size();
4752 elfcpp::DT rel_tag;
4753 int rel_size;
4754 if (use_rel)
4755 {
4756 rel_tag = elfcpp::DT_RELENT;
4757 if (size == 32)
4758 rel_size = Reloc_types<elfcpp::SHT_REL, 32, false>::reloc_size;
4759 else if (size == 64)
4760 rel_size = Reloc_types<elfcpp::SHT_REL, 64, false>::reloc_size;
4761 else
4762 gold_unreachable();
4763 }
4764 else
4765 {
4766 rel_tag = elfcpp::DT_RELAENT;
4767 if (size == 32)
4768 rel_size = Reloc_types<elfcpp::SHT_RELA, 32, false>::reloc_size;
4769 else if (size == 64)
4770 rel_size = Reloc_types<elfcpp::SHT_RELA, 64, false>::reloc_size;
4771 else
4772 gold_unreachable();
4773 }
4774 odyn->add_constant(rel_tag, rel_size);
4775
4776 if (parameters->options().combreloc() && have_dyn_rel)
4777 {
4778 size_t c = dyn_rel->relative_reloc_count();
4779 if (c > 0)
4780 odyn->add_constant((use_rel
4781 ? elfcpp::DT_RELCOUNT
4782 : elfcpp::DT_RELACOUNT),
4783 c);
4784 }
4785 }
4786
4787 if (dyn_relr != NULL && dyn_relr->output_section() != NULL)
4788 {
4789 const int size = parameters->target().get_size();
4790 odyn->add_section_address(elfcpp::DT_RELR, dyn_relr->output_section());
4791 odyn->add_section_size(elfcpp::DT_RELRSZ, dyn_relr->output_section());
4792 odyn->add_constant(elfcpp::DT_RELRENT, size / 8);
4793 if (parameters->options().combreloc())
4794 odyn->add_constant(elfcpp::DT_RELRCOUNT,
4795 dyn_relr->relative_reloc_count());
4796 }
4797
4798 if (add_debug && !parameters->options().shared())
4799 {
4800 // The value of the DT_DEBUG tag is filled in by the dynamic
4801 // linker at run time, and used by the debugger.
4802 odyn->add_constant(elfcpp::DT_DEBUG, 0);
4803 }
4804 }
4805
4806 void
add_target_specific_dynamic_tag(elfcpp::DT tag,unsigned int val)4807 Layout::add_target_specific_dynamic_tag(elfcpp::DT tag, unsigned int val)
4808 {
4809 Output_data_dynamic* odyn = this->dynamic_data_;
4810 if (odyn == NULL)
4811 return;
4812 odyn->add_constant(tag, val);
4813 }
4814
4815 // Finish the .dynamic section and PT_DYNAMIC segment.
4816
4817 void
finish_dynamic_section(const Input_objects * input_objects,const Symbol_table * symtab)4818 Layout::finish_dynamic_section(const Input_objects* input_objects,
4819 const Symbol_table* symtab)
4820 {
4821 if (!this->script_options_->saw_phdrs_clause()
4822 && this->dynamic_section_ != NULL)
4823 {
4824 Output_segment* oseg = this->make_output_segment(elfcpp::PT_DYNAMIC,
4825 (elfcpp::PF_R
4826 | elfcpp::PF_W));
4827 oseg->add_output_section_to_nonload(this->dynamic_section_,
4828 elfcpp::PF_R | elfcpp::PF_W);
4829 }
4830
4831 Output_data_dynamic* const odyn = this->dynamic_data_;
4832 if (odyn == NULL)
4833 return;
4834
4835 for (Input_objects::Dynobj_iterator p = input_objects->dynobj_begin();
4836 p != input_objects->dynobj_end();
4837 ++p)
4838 {
4839 if (!(*p)->is_needed() && (*p)->as_needed())
4840 {
4841 // This dynamic object was linked with --as-needed, but it
4842 // is not needed.
4843 continue;
4844 }
4845
4846 odyn->add_string(elfcpp::DT_NEEDED, (*p)->soname());
4847 }
4848
4849 if (parameters->options().shared())
4850 {
4851 const char* soname = parameters->options().soname();
4852 if (soname != NULL)
4853 odyn->add_string(elfcpp::DT_SONAME, soname);
4854 }
4855
4856 Symbol* sym = symtab->lookup(parameters->options().init());
4857 if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj())
4858 odyn->add_symbol(elfcpp::DT_INIT, sym);
4859
4860 sym = symtab->lookup(parameters->options().fini());
4861 if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj())
4862 odyn->add_symbol(elfcpp::DT_FINI, sym);
4863
4864 // Look for .init_array, .preinit_array and .fini_array by checking
4865 // section types.
4866 for(Layout::Section_list::const_iterator p = this->section_list_.begin();
4867 p != this->section_list_.end();
4868 ++p)
4869 switch((*p)->type())
4870 {
4871 case elfcpp::SHT_FINI_ARRAY:
4872 odyn->add_section_address(elfcpp::DT_FINI_ARRAY, *p);
4873 odyn->add_section_size(elfcpp::DT_FINI_ARRAYSZ, *p);
4874 break;
4875 case elfcpp::SHT_INIT_ARRAY:
4876 odyn->add_section_address(elfcpp::DT_INIT_ARRAY, *p);
4877 odyn->add_section_size(elfcpp::DT_INIT_ARRAYSZ, *p);
4878 break;
4879 case elfcpp::SHT_PREINIT_ARRAY:
4880 odyn->add_section_address(elfcpp::DT_PREINIT_ARRAY, *p);
4881 odyn->add_section_size(elfcpp::DT_PREINIT_ARRAYSZ, *p);
4882 break;
4883 default:
4884 break;
4885 }
4886
4887 // Add a DT_RPATH entry if needed.
4888 const General_options::Dir_list& rpath(parameters->options().rpath());
4889 if (!rpath.empty())
4890 {
4891 std::string rpath_val;
4892 for (General_options::Dir_list::const_iterator p = rpath.begin();
4893 p != rpath.end();
4894 ++p)
4895 {
4896 if (rpath_val.empty())
4897 rpath_val = p->name();
4898 else
4899 {
4900 // Eliminate duplicates.
4901 General_options::Dir_list::const_iterator q;
4902 for (q = rpath.begin(); q != p; ++q)
4903 if (q->name() == p->name())
4904 break;
4905 if (q == p)
4906 {
4907 rpath_val += ':';
4908 rpath_val += p->name();
4909 }
4910 }
4911 }
4912
4913 if (!parameters->options().enable_new_dtags())
4914 odyn->add_string(elfcpp::DT_RPATH, rpath_val);
4915 else
4916 odyn->add_string(elfcpp::DT_RUNPATH, rpath_val);
4917 }
4918
4919 // Look for text segments that have dynamic relocations.
4920 bool have_textrel = false;
4921 if (!this->script_options_->saw_sections_clause())
4922 {
4923 for (Segment_list::const_iterator p = this->segment_list_.begin();
4924 p != this->segment_list_.end();
4925 ++p)
4926 {
4927 if ((*p)->type() == elfcpp::PT_LOAD
4928 && ((*p)->flags() & elfcpp::PF_W) == 0
4929 && (*p)->has_dynamic_reloc())
4930 {
4931 have_textrel = true;
4932 break;
4933 }
4934 }
4935 }
4936 else
4937 {
4938 // We don't know the section -> segment mapping, so we are
4939 // conservative and just look for readonly sections with
4940 // relocations. If those sections wind up in writable segments,
4941 // then we have created an unnecessary DT_TEXTREL entry.
4942 for (Section_list::const_iterator p = this->section_list_.begin();
4943 p != this->section_list_.end();
4944 ++p)
4945 {
4946 if (((*p)->flags() & elfcpp::SHF_ALLOC) != 0
4947 && ((*p)->flags() & elfcpp::SHF_WRITE) == 0
4948 && (*p)->has_dynamic_reloc())
4949 {
4950 have_textrel = true;
4951 break;
4952 }
4953 }
4954 }
4955
4956 if (parameters->options().filter() != NULL)
4957 odyn->add_string(elfcpp::DT_FILTER, parameters->options().filter());
4958 if (parameters->options().any_auxiliary())
4959 {
4960 for (options::String_set::const_iterator p =
4961 parameters->options().auxiliary_begin();
4962 p != parameters->options().auxiliary_end();
4963 ++p)
4964 odyn->add_string(elfcpp::DT_AUXILIARY, *p);
4965 }
4966
4967 // Add a DT_FLAGS entry if necessary.
4968 unsigned int flags = 0;
4969 if (have_textrel)
4970 {
4971 // Add a DT_TEXTREL for compatibility with older loaders.
4972 odyn->add_constant(elfcpp::DT_TEXTREL, 0);
4973 flags |= elfcpp::DF_TEXTREL;
4974
4975 if (parameters->options().text())
4976 gold_error(_("read-only segment has dynamic relocations"));
4977 else if (parameters->options().warn_shared_textrel()
4978 && parameters->options().shared())
4979 gold_warning(_("shared library text segment is not shareable"));
4980 }
4981 if (parameters->options().shared() && this->has_static_tls())
4982 flags |= elfcpp::DF_STATIC_TLS;
4983 if (parameters->options().origin())
4984 flags |= elfcpp::DF_ORIGIN;
4985 if (parameters->options().Bsymbolic()
4986 && !parameters->options().have_dynamic_list())
4987 {
4988 flags |= elfcpp::DF_SYMBOLIC;
4989 // Add DT_SYMBOLIC for compatibility with older loaders.
4990 odyn->add_constant(elfcpp::DT_SYMBOLIC, 0);
4991 }
4992 if (parameters->options().now())
4993 flags |= elfcpp::DF_BIND_NOW;
4994 if (flags != 0)
4995 odyn->add_constant(elfcpp::DT_FLAGS, flags);
4996
4997 flags = 0;
4998 if (parameters->options().global())
4999 flags |= elfcpp::DF_1_GLOBAL;
5000 if (parameters->options().initfirst())
5001 flags |= elfcpp::DF_1_INITFIRST;
5002 if (parameters->options().interpose())
5003 flags |= elfcpp::DF_1_INTERPOSE;
5004 if (parameters->options().loadfltr())
5005 flags |= elfcpp::DF_1_LOADFLTR;
5006 if (parameters->options().nodefaultlib())
5007 flags |= elfcpp::DF_1_NODEFLIB;
5008 if (parameters->options().nodelete())
5009 flags |= elfcpp::DF_1_NODELETE;
5010 if (parameters->options().nodlopen())
5011 flags |= elfcpp::DF_1_NOOPEN;
5012 if (parameters->options().nodump())
5013 flags |= elfcpp::DF_1_NODUMP;
5014 if (!parameters->options().shared())
5015 flags &= ~(elfcpp::DF_1_INITFIRST
5016 | elfcpp::DF_1_NODELETE
5017 | elfcpp::DF_1_NOOPEN);
5018 if (parameters->options().origin())
5019 flags |= elfcpp::DF_1_ORIGIN;
5020 if (parameters->options().now())
5021 flags |= elfcpp::DF_1_NOW;
5022 if (parameters->options().Bgroup())
5023 flags |= elfcpp::DF_1_GROUP;
5024 if (flags != 0)
5025 odyn->add_constant(elfcpp::DT_FLAGS_1, flags);
5026 }
5027
5028 // Set the size of the _DYNAMIC symbol table to be the size of the
5029 // dynamic data.
5030
5031 void
set_dynamic_symbol_size(const Symbol_table * symtab)5032 Layout::set_dynamic_symbol_size(const Symbol_table* symtab)
5033 {
5034 Output_data_dynamic* const odyn = this->dynamic_data_;
5035 if (odyn == NULL)
5036 return;
5037 odyn->finalize_data_size();
5038 if (this->dynamic_symbol_ == NULL)
5039 return;
5040 off_t data_size = odyn->data_size();
5041 const int size = parameters->target().get_size();
5042 if (size == 32)
5043 symtab->get_sized_symbol<32>(this->dynamic_symbol_)->set_symsize(data_size);
5044 else if (size == 64)
5045 symtab->get_sized_symbol<64>(this->dynamic_symbol_)->set_symsize(data_size);
5046 else
5047 gold_unreachable();
5048 }
5049
5050 // The mapping of input section name prefixes to output section names.
5051 // In some cases one prefix is itself a prefix of another prefix; in
5052 // such a case the longer prefix must come first. These prefixes are
5053 // based on the GNU linker default ELF linker script.
5054
5055 #define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 }
5056 #define MAPPING_INIT_EXACT(f, t) { f, 0, t, sizeof(t) - 1 }
5057 const Layout::Section_name_mapping Layout::section_name_mapping[] =
5058 {
5059 MAPPING_INIT(".text.", ".text"),
5060 MAPPING_INIT(".rodata.", ".rodata"),
5061 MAPPING_INIT(".data.rel.ro.local.", ".data.rel.ro.local"),
5062 MAPPING_INIT_EXACT(".data.rel.ro.local", ".data.rel.ro.local"),
5063 MAPPING_INIT(".data.rel.ro.", ".data.rel.ro"),
5064 MAPPING_INIT_EXACT(".data.rel.ro", ".data.rel.ro"),
5065 MAPPING_INIT(".data.", ".data"),
5066 MAPPING_INIT(".bss.", ".bss"),
5067 MAPPING_INIT(".tdata.", ".tdata"),
5068 MAPPING_INIT(".tbss.", ".tbss"),
5069 MAPPING_INIT(".init_array.", ".init_array"),
5070 MAPPING_INIT(".fini_array.", ".fini_array"),
5071 MAPPING_INIT(".sdata.", ".sdata"),
5072 MAPPING_INIT(".sbss.", ".sbss"),
5073 // FIXME: In the GNU linker, .sbss2 and .sdata2 are handled
5074 // differently depending on whether it is creating a shared library.
5075 MAPPING_INIT(".sdata2.", ".sdata"),
5076 MAPPING_INIT(".sbss2.", ".sbss"),
5077 MAPPING_INIT(".lrodata.", ".lrodata"),
5078 MAPPING_INIT(".ldata.", ".ldata"),
5079 MAPPING_INIT(".lbss.", ".lbss"),
5080 MAPPING_INIT(".gcc_except_table.", ".gcc_except_table"),
5081 MAPPING_INIT(".gnu.linkonce.d.rel.ro.local.", ".data.rel.ro.local"),
5082 MAPPING_INIT(".gnu.linkonce.d.rel.ro.", ".data.rel.ro"),
5083 MAPPING_INIT(".gnu.linkonce.t.", ".text"),
5084 MAPPING_INIT(".gnu.linkonce.r.", ".rodata"),
5085 MAPPING_INIT(".gnu.linkonce.d.", ".data"),
5086 MAPPING_INIT(".gnu.linkonce.b.", ".bss"),
5087 MAPPING_INIT(".gnu.linkonce.s.", ".sdata"),
5088 MAPPING_INIT(".gnu.linkonce.sb.", ".sbss"),
5089 MAPPING_INIT(".gnu.linkonce.s2.", ".sdata"),
5090 MAPPING_INIT(".gnu.linkonce.sb2.", ".sbss"),
5091 MAPPING_INIT(".gnu.linkonce.wi.", ".debug_info"),
5092 MAPPING_INIT(".gnu.linkonce.td.", ".tdata"),
5093 MAPPING_INIT(".gnu.linkonce.tb.", ".tbss"),
5094 MAPPING_INIT(".gnu.linkonce.lr.", ".lrodata"),
5095 MAPPING_INIT(".gnu.linkonce.l.", ".ldata"),
5096 MAPPING_INIT(".gnu.linkonce.lb.", ".lbss"),
5097 MAPPING_INIT(".ARM.extab", ".ARM.extab"),
5098 MAPPING_INIT(".gnu.linkonce.armextab.", ".ARM.extab"),
5099 MAPPING_INIT(".ARM.exidx", ".ARM.exidx"),
5100 MAPPING_INIT(".gnu.linkonce.armexidx.", ".ARM.exidx"),
5101 MAPPING_INIT("_function_patch_prologue.", "_function_patch_prologue"),
5102 MAPPING_INIT("_function_patch_epilogue.", "_function_patch_epilogue"),
5103 };
5104 #undef MAPPING_INIT
5105 #undef MAPPING_INIT_EXACT
5106
5107 const int Layout::section_name_mapping_count =
5108 (sizeof(Layout::section_name_mapping)
5109 / sizeof(Layout::section_name_mapping[0]));
5110
5111 // Choose the output section name to use given an input section name.
5112 // Set *PLEN to the length of the name. *PLEN is initialized to the
5113 // length of NAME.
5114
5115 const char*
output_section_name(const Relobj * relobj,const char * name,size_t * plen)5116 Layout::output_section_name(const Relobj* relobj, const char* name,
5117 size_t* plen)
5118 {
5119 // gcc 4.3 generates the following sorts of section names when it
5120 // needs a section name specific to a function:
5121 // .text.FN
5122 // .rodata.FN
5123 // .sdata2.FN
5124 // .data.FN
5125 // .data.rel.FN
5126 // .data.rel.local.FN
5127 // .data.rel.ro.FN
5128 // .data.rel.ro.local.FN
5129 // .sdata.FN
5130 // .bss.FN
5131 // .sbss.FN
5132 // .tdata.FN
5133 // .tbss.FN
5134
5135 // The GNU linker maps all of those to the part before the .FN,
5136 // except that .data.rel.local.FN is mapped to .data, and
5137 // .data.rel.ro.local.FN is mapped to .data.rel.ro. The sections
5138 // beginning with .data.rel.ro.local are grouped together.
5139
5140 // For an anonymous namespace, the string FN can contain a '.'.
5141
5142 // Also of interest: .rodata.strN.N, .rodata.cstN, both of which the
5143 // GNU linker maps to .rodata.
5144
5145 // The .data.rel.ro sections are used with -z relro. The sections
5146 // are recognized by name. We use the same names that the GNU
5147 // linker does for these sections.
5148
5149 // It is hard to handle this in a principled way, so we don't even
5150 // try. We use a table of mappings. If the input section name is
5151 // not found in the table, we simply use it as the output section
5152 // name.
5153
5154 const Section_name_mapping* psnm = section_name_mapping;
5155 for (int i = 0; i < section_name_mapping_count; ++i, ++psnm)
5156 {
5157 if (psnm->fromlen > 0)
5158 {
5159 if (strncmp(name, psnm->from, psnm->fromlen) == 0)
5160 {
5161 *plen = psnm->tolen;
5162 return psnm->to;
5163 }
5164 }
5165 else
5166 {
5167 if (strcmp(name, psnm->from) == 0)
5168 {
5169 *plen = psnm->tolen;
5170 return psnm->to;
5171 }
5172 }
5173 }
5174
5175 // As an additional complication, .ctors sections are output in
5176 // either .ctors or .init_array sections, and .dtors sections are
5177 // output in either .dtors or .fini_array sections.
5178 if (is_prefix_of(".ctors.", name) || is_prefix_of(".dtors.", name))
5179 {
5180 if (parameters->options().ctors_in_init_array())
5181 {
5182 *plen = 11;
5183 return name[1] == 'c' ? ".init_array" : ".fini_array";
5184 }
5185 else
5186 {
5187 *plen = 6;
5188 return name[1] == 'c' ? ".ctors" : ".dtors";
5189 }
5190 }
5191 if (parameters->options().ctors_in_init_array()
5192 && (strcmp(name, ".ctors") == 0 || strcmp(name, ".dtors") == 0))
5193 {
5194 // To make .init_array/.fini_array work with gcc we must exclude
5195 // .ctors and .dtors sections from the crtbegin and crtend
5196 // files.
5197 if (relobj == NULL
5198 || (!Layout::match_file_name(relobj, "crtbegin")
5199 && !Layout::match_file_name(relobj, "crtend")))
5200 {
5201 *plen = 11;
5202 return name[1] == 'c' ? ".init_array" : ".fini_array";
5203 }
5204 }
5205
5206 return name;
5207 }
5208
5209 // Return true if RELOBJ is an input file whose base name matches
5210 // FILE_NAME. The base name must have an extension of ".o", and must
5211 // be exactly FILE_NAME.o or FILE_NAME, one character, ".o". This is
5212 // to match crtbegin.o as well as crtbeginS.o without getting confused
5213 // by other possibilities. Overall matching the file name this way is
5214 // a dreadful hack, but the GNU linker does it in order to better
5215 // support gcc, and we need to be compatible.
5216
5217 bool
match_file_name(const Relobj * relobj,const char * match)5218 Layout::match_file_name(const Relobj* relobj, const char* match)
5219 {
5220 const std::string& file_name(relobj->name());
5221 const char* base_name = lbasename(file_name.c_str());
5222 size_t match_len = strlen(match);
5223 if (strncmp(base_name, match, match_len) != 0)
5224 return false;
5225 size_t base_len = strlen(base_name);
5226 if (base_len != match_len + 2 && base_len != match_len + 3)
5227 return false;
5228 return memcmp(base_name + base_len - 2, ".o", 2) == 0;
5229 }
5230
5231 // Check if a comdat group or .gnu.linkonce section with the given
5232 // NAME is selected for the link. If there is already a section,
5233 // *KEPT_SECTION is set to point to the existing section and the
5234 // function returns false. Otherwise, OBJECT, SHNDX, IS_COMDAT, and
5235 // IS_GROUP_NAME are recorded for this NAME in the layout object,
5236 // *KEPT_SECTION is set to the internal copy and the function returns
5237 // true.
5238
5239 bool
find_or_add_kept_section(const std::string & name,Relobj * object,unsigned int shndx,bool is_comdat,bool is_group_name,Kept_section ** kept_section)5240 Layout::find_or_add_kept_section(const std::string& name,
5241 Relobj* object,
5242 unsigned int shndx,
5243 bool is_comdat,
5244 bool is_group_name,
5245 Kept_section** kept_section)
5246 {
5247 // It's normal to see a couple of entries here, for the x86 thunk
5248 // sections. If we see more than a few, we're linking a C++
5249 // program, and we resize to get more space to minimize rehashing.
5250 if (this->signatures_.size() > 4
5251 && !this->resized_signatures_)
5252 {
5253 reserve_unordered_map(&this->signatures_,
5254 this->number_of_input_files_ * 64);
5255 this->resized_signatures_ = true;
5256 }
5257
5258 Kept_section candidate;
5259 std::pair<Signatures::iterator, bool> ins =
5260 this->signatures_.insert(std::make_pair(name, candidate));
5261
5262 if (kept_section != NULL)
5263 *kept_section = &ins.first->second;
5264 if (ins.second)
5265 {
5266 // This is the first time we've seen this signature.
5267 ins.first->second.set_object(object);
5268 ins.first->second.set_shndx(shndx);
5269 if (is_comdat)
5270 ins.first->second.set_is_comdat();
5271 if (is_group_name)
5272 ins.first->second.set_is_group_name();
5273 return true;
5274 }
5275
5276 // We have already seen this signature.
5277
5278 if (ins.first->second.is_group_name())
5279 {
5280 // We've already seen a real section group with this signature.
5281 // If the kept group is from a plugin object, and we're in the
5282 // replacement phase, accept the new one as a replacement.
5283 if (ins.first->second.object() == NULL
5284 && parameters->options().plugins()->in_replacement_phase())
5285 {
5286 ins.first->second.set_object(object);
5287 ins.first->second.set_shndx(shndx);
5288 return true;
5289 }
5290 return false;
5291 }
5292 else if (is_group_name)
5293 {
5294 // This is a real section group, and we've already seen a
5295 // linkonce section with this signature. Record that we've seen
5296 // a section group, and don't include this section group.
5297 ins.first->second.set_is_group_name();
5298 return false;
5299 }
5300 else
5301 {
5302 // We've already seen a linkonce section and this is a linkonce
5303 // section. These don't block each other--this may be the same
5304 // symbol name with different section types.
5305 return true;
5306 }
5307 }
5308
5309 // Store the allocated sections into the section list.
5310
5311 void
get_allocated_sections(Section_list * section_list) const5312 Layout::get_allocated_sections(Section_list* section_list) const
5313 {
5314 for (Section_list::const_iterator p = this->section_list_.begin();
5315 p != this->section_list_.end();
5316 ++p)
5317 if (((*p)->flags() & elfcpp::SHF_ALLOC) != 0)
5318 section_list->push_back(*p);
5319 }
5320
5321 // Store the executable sections into the section list.
5322
5323 void
get_executable_sections(Section_list * section_list) const5324 Layout::get_executable_sections(Section_list* section_list) const
5325 {
5326 for (Section_list::const_iterator p = this->section_list_.begin();
5327 p != this->section_list_.end();
5328 ++p)
5329 if (((*p)->flags() & (elfcpp::SHF_ALLOC | elfcpp::SHF_EXECINSTR))
5330 == (elfcpp::SHF_ALLOC | elfcpp::SHF_EXECINSTR))
5331 section_list->push_back(*p);
5332 }
5333
5334 // Create an output segment.
5335
5336 Output_segment*
make_output_segment(elfcpp::Elf_Word type,elfcpp::Elf_Word flags)5337 Layout::make_output_segment(elfcpp::Elf_Word type, elfcpp::Elf_Word flags)
5338 {
5339 gold_assert(!parameters->options().relocatable());
5340 Output_segment* oseg = new Output_segment(type, flags);
5341 this->segment_list_.push_back(oseg);
5342
5343 if (type == elfcpp::PT_TLS)
5344 this->tls_segment_ = oseg;
5345 else if (type == elfcpp::PT_GNU_RELRO)
5346 this->relro_segment_ = oseg;
5347 else if (type == elfcpp::PT_INTERP)
5348 this->interp_segment_ = oseg;
5349
5350 return oseg;
5351 }
5352
5353 // Return the file offset of the normal symbol table.
5354
5355 off_t
symtab_section_offset() const5356 Layout::symtab_section_offset() const
5357 {
5358 if (this->symtab_section_ != NULL)
5359 return this->symtab_section_->offset();
5360 return 0;
5361 }
5362
5363 // Return the section index of the normal symbol table. It may have
5364 // been stripped by the -s/--strip-all option.
5365
5366 unsigned int
symtab_section_shndx() const5367 Layout::symtab_section_shndx() const
5368 {
5369 if (this->symtab_section_ != NULL)
5370 return this->symtab_section_->out_shndx();
5371 return 0;
5372 }
5373
5374 // Write out the Output_sections. Most won't have anything to write,
5375 // since most of the data will come from input sections which are
5376 // handled elsewhere. But some Output_sections do have Output_data.
5377
5378 void
write_output_sections(Output_file * of) const5379 Layout::write_output_sections(Output_file* of) const
5380 {
5381 for (Section_list::const_iterator p = this->section_list_.begin();
5382 p != this->section_list_.end();
5383 ++p)
5384 {
5385 if (!(*p)->after_input_sections())
5386 (*p)->write(of);
5387 }
5388 }
5389
5390 // Write out data not associated with a section or the symbol table.
5391
5392 void
write_data(const Symbol_table * symtab,Output_file * of) const5393 Layout::write_data(const Symbol_table* symtab, Output_file* of) const
5394 {
5395 if (!parameters->options().strip_all())
5396 {
5397 const Output_section* symtab_section = this->symtab_section_;
5398 for (Section_list::const_iterator p = this->section_list_.begin();
5399 p != this->section_list_.end();
5400 ++p)
5401 {
5402 if ((*p)->needs_symtab_index())
5403 {
5404 gold_assert(symtab_section != NULL);
5405 unsigned int index = (*p)->symtab_index();
5406 gold_assert(index > 0 && index != -1U);
5407 off_t off = (symtab_section->offset()
5408 + index * symtab_section->entsize());
5409 symtab->write_section_symbol(*p, this->symtab_xindex_, of, off);
5410 }
5411 }
5412 }
5413
5414 const Output_section* dynsym_section = this->dynsym_section_;
5415 for (Section_list::const_iterator p = this->section_list_.begin();
5416 p != this->section_list_.end();
5417 ++p)
5418 {
5419 if ((*p)->needs_dynsym_index())
5420 {
5421 gold_assert(dynsym_section != NULL);
5422 unsigned int index = (*p)->dynsym_index();
5423 gold_assert(index > 0 && index != -1U);
5424 off_t off = (dynsym_section->offset()
5425 + index * dynsym_section->entsize());
5426 symtab->write_section_symbol(*p, this->dynsym_xindex_, of, off);
5427 }
5428 }
5429
5430 // Write out the Output_data which are not in an Output_section.
5431 for (Data_list::const_iterator p = this->special_output_list_.begin();
5432 p != this->special_output_list_.end();
5433 ++p)
5434 (*p)->write(of);
5435
5436 // Write out the Output_data which are not in an Output_section
5437 // and are regenerated in each iteration of relaxation.
5438 for (Data_list::const_iterator p = this->relax_output_list_.begin();
5439 p != this->relax_output_list_.end();
5440 ++p)
5441 (*p)->write(of);
5442 }
5443
5444 // Write out the Output_sections which can only be written after the
5445 // input sections are complete.
5446
5447 void
write_sections_after_input_sections(Output_file * of)5448 Layout::write_sections_after_input_sections(Output_file* of)
5449 {
5450 // Determine the final section offsets, and thus the final output
5451 // file size. Note we finalize the .shstrab last, to allow the
5452 // after_input_section sections to modify their section-names before
5453 // writing.
5454 if (this->any_postprocessing_sections_)
5455 {
5456 off_t off = this->output_file_size_;
5457 off = this->set_section_offsets(off, POSTPROCESSING_SECTIONS_PASS);
5458
5459 // Now that we've finalized the names, we can finalize the shstrab.
5460 off =
5461 this->set_section_offsets(off,
5462 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS);
5463
5464 if (off > this->output_file_size_)
5465 {
5466 of->resize(off);
5467 this->output_file_size_ = off;
5468 }
5469 }
5470
5471 for (Section_list::const_iterator p = this->section_list_.begin();
5472 p != this->section_list_.end();
5473 ++p)
5474 {
5475 if ((*p)->after_input_sections())
5476 (*p)->write(of);
5477 }
5478
5479 this->section_headers_->write(of);
5480 }
5481
5482 // If a tree-style build ID was requested, the parallel part of that computation
5483 // is already done, and the final hash-of-hashes is computed here. For other
5484 // types of build IDs, all the work is done here.
5485
5486 void
write_build_id(Output_file * of,unsigned char * array_of_hashes,size_t size_of_hashes) const5487 Layout::write_build_id(Output_file* of, unsigned char* array_of_hashes,
5488 size_t size_of_hashes) const
5489 {
5490 if (this->build_id_note_ == NULL)
5491 return;
5492
5493 unsigned char* ov = of->get_output_view(this->build_id_note_->offset(),
5494 this->build_id_note_->data_size());
5495
5496 if (array_of_hashes == NULL)
5497 {
5498 const size_t output_file_size = this->output_file_size();
5499 const unsigned char* iv = of->get_input_view(0, output_file_size);
5500 const char* style = parameters->options().build_id();
5501
5502 // If we get here with style == "tree" then the output must be
5503 // too small for chunking, and we use SHA-1 in that case.
5504 if ((strcmp(style, "sha1") == 0) || (strcmp(style, "tree") == 0))
5505 sha1_buffer(reinterpret_cast<const char*>(iv), output_file_size, ov);
5506 else if (strcmp(style, "md5") == 0)
5507 md5_buffer(reinterpret_cast<const char*>(iv), output_file_size, ov);
5508 else
5509 gold_unreachable();
5510
5511 of->free_input_view(0, output_file_size, iv);
5512 }
5513 else
5514 {
5515 // Non-overlapping substrings of the output file have been hashed.
5516 // Compute SHA-1 hash of the hashes.
5517 sha1_buffer(reinterpret_cast<const char*>(array_of_hashes),
5518 size_of_hashes, ov);
5519 delete[] array_of_hashes;
5520 }
5521
5522 of->write_output_view(this->build_id_note_->offset(),
5523 this->build_id_note_->data_size(),
5524 ov);
5525 }
5526
5527 // Write out a binary file. This is called after the link is
5528 // complete. IN is the temporary output file we used to generate the
5529 // ELF code. We simply walk through the segments, read them from
5530 // their file offset in IN, and write them to their load address in
5531 // the output file. FIXME: with a bit more work, we could support
5532 // S-records and/or Intel hex format here.
5533
5534 void
write_binary(Output_file * in) const5535 Layout::write_binary(Output_file* in) const
5536 {
5537 gold_assert(parameters->options().oformat_enum()
5538 == General_options::OBJECT_FORMAT_BINARY);
5539
5540 // Get the size of the binary file.
5541 uint64_t max_load_address = 0;
5542 for (Segment_list::const_iterator p = this->segment_list_.begin();
5543 p != this->segment_list_.end();
5544 ++p)
5545 {
5546 if ((*p)->type() == elfcpp::PT_LOAD && (*p)->filesz() > 0)
5547 {
5548 uint64_t max_paddr = (*p)->paddr() + (*p)->filesz();
5549 if (max_paddr > max_load_address)
5550 max_load_address = max_paddr;
5551 }
5552 }
5553
5554 Output_file out(parameters->options().output_file_name());
5555 out.open(max_load_address);
5556
5557 for (Segment_list::const_iterator p = this->segment_list_.begin();
5558 p != this->segment_list_.end();
5559 ++p)
5560 {
5561 if ((*p)->type() == elfcpp::PT_LOAD && (*p)->filesz() > 0)
5562 {
5563 const unsigned char* vin = in->get_input_view((*p)->offset(),
5564 (*p)->filesz());
5565 unsigned char* vout = out.get_output_view((*p)->paddr(),
5566 (*p)->filesz());
5567 memcpy(vout, vin, (*p)->filesz());
5568 out.write_output_view((*p)->paddr(), (*p)->filesz(), vout);
5569 in->free_input_view((*p)->offset(), (*p)->filesz(), vin);
5570 }
5571 }
5572
5573 out.close();
5574 }
5575
5576 // Print the output sections to the map file.
5577
5578 void
print_to_mapfile(Mapfile * mapfile) const5579 Layout::print_to_mapfile(Mapfile* mapfile) const
5580 {
5581 for (Segment_list::const_iterator p = this->segment_list_.begin();
5582 p != this->segment_list_.end();
5583 ++p)
5584 (*p)->print_sections_to_mapfile(mapfile);
5585 for (Section_list::const_iterator p = this->unattached_section_list_.begin();
5586 p != this->unattached_section_list_.end();
5587 ++p)
5588 (*p)->print_to_mapfile(mapfile);
5589 }
5590
5591 // Print statistical information to stderr. This is used for --stats.
5592
5593 void
print_stats() const5594 Layout::print_stats() const
5595 {
5596 this->namepool_.print_stats("section name pool");
5597 this->sympool_.print_stats("output symbol name pool");
5598 this->dynpool_.print_stats("dynamic name pool");
5599
5600 for (Section_list::const_iterator p = this->section_list_.begin();
5601 p != this->section_list_.end();
5602 ++p)
5603 (*p)->print_merge_stats();
5604 }
5605
5606 // Write_sections_task methods.
5607
5608 // We can always run this task.
5609
5610 Task_token*
is_runnable()5611 Write_sections_task::is_runnable()
5612 {
5613 return NULL;
5614 }
5615
5616 // We need to unlock both OUTPUT_SECTIONS_BLOCKER and FINAL_BLOCKER
5617 // when finished.
5618
5619 void
locks(Task_locker * tl)5620 Write_sections_task::locks(Task_locker* tl)
5621 {
5622 tl->add(this, this->output_sections_blocker_);
5623 if (this->input_sections_blocker_ != NULL)
5624 tl->add(this, this->input_sections_blocker_);
5625 tl->add(this, this->final_blocker_);
5626 }
5627
5628 // Run the task--write out the data.
5629
5630 void
run(Workqueue *)5631 Write_sections_task::run(Workqueue*)
5632 {
5633 this->layout_->write_output_sections(this->of_);
5634 }
5635
5636 // Write_data_task methods.
5637
5638 // We can always run this task.
5639
5640 Task_token*
is_runnable()5641 Write_data_task::is_runnable()
5642 {
5643 return NULL;
5644 }
5645
5646 // We need to unlock FINAL_BLOCKER when finished.
5647
5648 void
locks(Task_locker * tl)5649 Write_data_task::locks(Task_locker* tl)
5650 {
5651 tl->add(this, this->final_blocker_);
5652 }
5653
5654 // Run the task--write out the data.
5655
5656 void
run(Workqueue *)5657 Write_data_task::run(Workqueue*)
5658 {
5659 this->layout_->write_data(this->symtab_, this->of_);
5660 }
5661
5662 // Write_symbols_task methods.
5663
5664 // We can always run this task.
5665
5666 Task_token*
is_runnable()5667 Write_symbols_task::is_runnable()
5668 {
5669 return NULL;
5670 }
5671
5672 // We need to unlock FINAL_BLOCKER when finished.
5673
5674 void
locks(Task_locker * tl)5675 Write_symbols_task::locks(Task_locker* tl)
5676 {
5677 tl->add(this, this->final_blocker_);
5678 }
5679
5680 // Run the task--write out the symbols.
5681
5682 void
run(Workqueue *)5683 Write_symbols_task::run(Workqueue*)
5684 {
5685 this->symtab_->write_globals(this->sympool_, this->dynpool_,
5686 this->layout_->symtab_xindex(),
5687 this->layout_->dynsym_xindex(), this->of_);
5688 }
5689
5690 // Write_after_input_sections_task methods.
5691
5692 // We can only run this task after the input sections have completed.
5693
5694 Task_token*
is_runnable()5695 Write_after_input_sections_task::is_runnable()
5696 {
5697 if (this->input_sections_blocker_->is_blocked())
5698 return this->input_sections_blocker_;
5699 return NULL;
5700 }
5701
5702 // We need to unlock FINAL_BLOCKER when finished.
5703
5704 void
locks(Task_locker * tl)5705 Write_after_input_sections_task::locks(Task_locker* tl)
5706 {
5707 tl->add(this, this->final_blocker_);
5708 }
5709
5710 // Run the task.
5711
5712 void
run(Workqueue *)5713 Write_after_input_sections_task::run(Workqueue*)
5714 {
5715 this->layout_->write_sections_after_input_sections(this->of_);
5716 }
5717
5718 // Build IDs can be computed as a "flat" sha1 or md5 of a string of bytes,
5719 // or as a "tree" where each chunk of the string is hashed and then those
5720 // hashes are put into a (much smaller) string which is hashed with sha1.
5721 // We compute a checksum over the entire file because that is simplest.
5722
5723 void
run(Workqueue * workqueue,const Task *)5724 Build_id_task_runner::run(Workqueue* workqueue, const Task*)
5725 {
5726 Task_token* post_hash_tasks_blocker = new Task_token(true);
5727 const Layout* layout = this->layout_;
5728 Output_file* of = this->of_;
5729 const size_t filesize = (layout->output_file_size() <= 0 ? 0
5730 : static_cast<size_t>(layout->output_file_size()));
5731 unsigned char* array_of_hashes = NULL;
5732 size_t size_of_hashes = 0;
5733
5734 if (strcmp(this->options_->build_id(), "tree") == 0
5735 && this->options_->build_id_chunk_size_for_treehash() > 0
5736 && filesize > 0
5737 && (filesize >= this->options_->build_id_min_file_size_for_treehash()))
5738 {
5739 static const size_t MD5_OUTPUT_SIZE_IN_BYTES = 16;
5740 const size_t chunk_size =
5741 this->options_->build_id_chunk_size_for_treehash();
5742 const size_t num_hashes = ((filesize - 1) / chunk_size) + 1;
5743 post_hash_tasks_blocker->add_blockers(num_hashes);
5744 size_of_hashes = num_hashes * MD5_OUTPUT_SIZE_IN_BYTES;
5745 array_of_hashes = new unsigned char[size_of_hashes];
5746 unsigned char *dst = array_of_hashes;
5747 for (size_t i = 0, src_offset = 0; i < num_hashes;
5748 i++, dst += MD5_OUTPUT_SIZE_IN_BYTES, src_offset += chunk_size)
5749 {
5750 size_t size = std::min(chunk_size, filesize - src_offset);
5751 workqueue->queue(new Hash_task(of,
5752 src_offset,
5753 size,
5754 dst,
5755 post_hash_tasks_blocker));
5756 }
5757 }
5758
5759 // Queue the final task to write the build id and close the output file.
5760 workqueue->queue(new Task_function(new Close_task_runner(this->options_,
5761 layout,
5762 of,
5763 array_of_hashes,
5764 size_of_hashes),
5765 post_hash_tasks_blocker,
5766 "Task_function Close_task_runner"));
5767 }
5768
5769 // Close_task_runner methods.
5770
5771 // Finish up the build ID computation, if necessary, and write a binary file,
5772 // if necessary. Then close the output file.
5773
5774 void
run(Workqueue *,const Task *)5775 Close_task_runner::run(Workqueue*, const Task*)
5776 {
5777 // At this point the multi-threaded part of the build ID computation,
5778 // if any, is done. See Build_id_task_runner.
5779 this->layout_->write_build_id(this->of_, this->array_of_hashes_,
5780 this->size_of_hashes_);
5781
5782 // If we've been asked to create a binary file, we do so here.
5783 if (this->options_->oformat_enum() != General_options::OBJECT_FORMAT_ELF)
5784 this->layout_->write_binary(this->of_);
5785
5786 this->of_->close();
5787 }
5788
5789 // Instantiate the templates we need. We could use the configure
5790 // script to restrict this to only the ones for implemented targets.
5791
5792 #ifdef HAVE_TARGET_32_LITTLE
5793 template
5794 Output_section*
5795 Layout::init_fixed_output_section<32, false>(
5796 const char* name,
5797 elfcpp::Shdr<32, false>& shdr);
5798 #endif
5799
5800 #ifdef HAVE_TARGET_32_BIG
5801 template
5802 Output_section*
5803 Layout::init_fixed_output_section<32, true>(
5804 const char* name,
5805 elfcpp::Shdr<32, true>& shdr);
5806 #endif
5807
5808 #ifdef HAVE_TARGET_64_LITTLE
5809 template
5810 Output_section*
5811 Layout::init_fixed_output_section<64, false>(
5812 const char* name,
5813 elfcpp::Shdr<64, false>& shdr);
5814 #endif
5815
5816 #ifdef HAVE_TARGET_64_BIG
5817 template
5818 Output_section*
5819 Layout::init_fixed_output_section<64, true>(
5820 const char* name,
5821 elfcpp::Shdr<64, true>& shdr);
5822 #endif
5823
5824 #ifdef HAVE_TARGET_32_LITTLE
5825 template
5826 Output_section*
5827 Layout::layout<32, false>(Sized_relobj_file<32, false>* object,
5828 unsigned int shndx,
5829 const char* name,
5830 const elfcpp::Shdr<32, false>& shdr,
5831 unsigned int, unsigned int, off_t*);
5832 #endif
5833
5834 #ifdef HAVE_TARGET_32_BIG
5835 template
5836 Output_section*
5837 Layout::layout<32, true>(Sized_relobj_file<32, true>* object,
5838 unsigned int shndx,
5839 const char* name,
5840 const elfcpp::Shdr<32, true>& shdr,
5841 unsigned int, unsigned int, off_t*);
5842 #endif
5843
5844 #ifdef HAVE_TARGET_64_LITTLE
5845 template
5846 Output_section*
5847 Layout::layout<64, false>(Sized_relobj_file<64, false>* object,
5848 unsigned int shndx,
5849 const char* name,
5850 const elfcpp::Shdr<64, false>& shdr,
5851 unsigned int, unsigned int, off_t*);
5852 #endif
5853
5854 #ifdef HAVE_TARGET_64_BIG
5855 template
5856 Output_section*
5857 Layout::layout<64, true>(Sized_relobj_file<64, true>* object,
5858 unsigned int shndx,
5859 const char* name,
5860 const elfcpp::Shdr<64, true>& shdr,
5861 unsigned int, unsigned int, off_t*);
5862 #endif
5863
5864 #ifdef HAVE_TARGET_32_LITTLE
5865 template
5866 Output_section*
5867 Layout::layout_reloc<32, false>(Sized_relobj_file<32, false>* object,
5868 unsigned int reloc_shndx,
5869 const elfcpp::Shdr<32, false>& shdr,
5870 Output_section* data_section,
5871 Relocatable_relocs* rr);
5872 #endif
5873
5874 #ifdef HAVE_TARGET_32_BIG
5875 template
5876 Output_section*
5877 Layout::layout_reloc<32, true>(Sized_relobj_file<32, true>* object,
5878 unsigned int reloc_shndx,
5879 const elfcpp::Shdr<32, true>& shdr,
5880 Output_section* data_section,
5881 Relocatable_relocs* rr);
5882 #endif
5883
5884 #ifdef HAVE_TARGET_64_LITTLE
5885 template
5886 Output_section*
5887 Layout::layout_reloc<64, false>(Sized_relobj_file<64, false>* object,
5888 unsigned int reloc_shndx,
5889 const elfcpp::Shdr<64, false>& shdr,
5890 Output_section* data_section,
5891 Relocatable_relocs* rr);
5892 #endif
5893
5894 #ifdef HAVE_TARGET_64_BIG
5895 template
5896 Output_section*
5897 Layout::layout_reloc<64, true>(Sized_relobj_file<64, true>* object,
5898 unsigned int reloc_shndx,
5899 const elfcpp::Shdr<64, true>& shdr,
5900 Output_section* data_section,
5901 Relocatable_relocs* rr);
5902 #endif
5903
5904 #ifdef HAVE_TARGET_32_LITTLE
5905 template
5906 void
5907 Layout::layout_group<32, false>(Symbol_table* symtab,
5908 Sized_relobj_file<32, false>* object,
5909 unsigned int,
5910 const char* group_section_name,
5911 const char* signature,
5912 const elfcpp::Shdr<32, false>& shdr,
5913 elfcpp::Elf_Word flags,
5914 std::vector<unsigned int>* shndxes);
5915 #endif
5916
5917 #ifdef HAVE_TARGET_32_BIG
5918 template
5919 void
5920 Layout::layout_group<32, true>(Symbol_table* symtab,
5921 Sized_relobj_file<32, true>* object,
5922 unsigned int,
5923 const char* group_section_name,
5924 const char* signature,
5925 const elfcpp::Shdr<32, true>& shdr,
5926 elfcpp::Elf_Word flags,
5927 std::vector<unsigned int>* shndxes);
5928 #endif
5929
5930 #ifdef HAVE_TARGET_64_LITTLE
5931 template
5932 void
5933 Layout::layout_group<64, false>(Symbol_table* symtab,
5934 Sized_relobj_file<64, false>* object,
5935 unsigned int,
5936 const char* group_section_name,
5937 const char* signature,
5938 const elfcpp::Shdr<64, false>& shdr,
5939 elfcpp::Elf_Word flags,
5940 std::vector<unsigned int>* shndxes);
5941 #endif
5942
5943 #ifdef HAVE_TARGET_64_BIG
5944 template
5945 void
5946 Layout::layout_group<64, true>(Symbol_table* symtab,
5947 Sized_relobj_file<64, true>* object,
5948 unsigned int,
5949 const char* group_section_name,
5950 const char* signature,
5951 const elfcpp::Shdr<64, true>& shdr,
5952 elfcpp::Elf_Word flags,
5953 std::vector<unsigned int>* shndxes);
5954 #endif
5955
5956 #ifdef HAVE_TARGET_32_LITTLE
5957 template
5958 Output_section*
5959 Layout::layout_eh_frame<32, false>(Sized_relobj_file<32, false>* object,
5960 const unsigned char* symbols,
5961 off_t symbols_size,
5962 const unsigned char* symbol_names,
5963 off_t symbol_names_size,
5964 unsigned int shndx,
5965 const elfcpp::Shdr<32, false>& shdr,
5966 unsigned int reloc_shndx,
5967 unsigned int reloc_type,
5968 off_t* off);
5969 #endif
5970
5971 #ifdef HAVE_TARGET_32_BIG
5972 template
5973 Output_section*
5974 Layout::layout_eh_frame<32, true>(Sized_relobj_file<32, true>* object,
5975 const unsigned char* symbols,
5976 off_t symbols_size,
5977 const unsigned char* symbol_names,
5978 off_t symbol_names_size,
5979 unsigned int shndx,
5980 const elfcpp::Shdr<32, true>& shdr,
5981 unsigned int reloc_shndx,
5982 unsigned int reloc_type,
5983 off_t* off);
5984 #endif
5985
5986 #ifdef HAVE_TARGET_64_LITTLE
5987 template
5988 Output_section*
5989 Layout::layout_eh_frame<64, false>(Sized_relobj_file<64, false>* object,
5990 const unsigned char* symbols,
5991 off_t symbols_size,
5992 const unsigned char* symbol_names,
5993 off_t symbol_names_size,
5994 unsigned int shndx,
5995 const elfcpp::Shdr<64, false>& shdr,
5996 unsigned int reloc_shndx,
5997 unsigned int reloc_type,
5998 off_t* off);
5999 #endif
6000
6001 #ifdef HAVE_TARGET_64_BIG
6002 template
6003 Output_section*
6004 Layout::layout_eh_frame<64, true>(Sized_relobj_file<64, true>* object,
6005 const unsigned char* symbols,
6006 off_t symbols_size,
6007 const unsigned char* symbol_names,
6008 off_t symbol_names_size,
6009 unsigned int shndx,
6010 const elfcpp::Shdr<64, true>& shdr,
6011 unsigned int reloc_shndx,
6012 unsigned int reloc_type,
6013 off_t* off);
6014 #endif
6015
6016 #ifdef HAVE_TARGET_32_LITTLE
6017 template
6018 void
6019 Layout::add_to_gdb_index(bool is_type_unit,
6020 Sized_relobj<32, false>* object,
6021 const unsigned char* symbols,
6022 off_t symbols_size,
6023 unsigned int shndx,
6024 unsigned int reloc_shndx,
6025 unsigned int reloc_type);
6026 #endif
6027
6028 #ifdef HAVE_TARGET_32_BIG
6029 template
6030 void
6031 Layout::add_to_gdb_index(bool is_type_unit,
6032 Sized_relobj<32, true>* object,
6033 const unsigned char* symbols,
6034 off_t symbols_size,
6035 unsigned int shndx,
6036 unsigned int reloc_shndx,
6037 unsigned int reloc_type);
6038 #endif
6039
6040 #ifdef HAVE_TARGET_64_LITTLE
6041 template
6042 void
6043 Layout::add_to_gdb_index(bool is_type_unit,
6044 Sized_relobj<64, false>* object,
6045 const unsigned char* symbols,
6046 off_t symbols_size,
6047 unsigned int shndx,
6048 unsigned int reloc_shndx,
6049 unsigned int reloc_type);
6050 #endif
6051
6052 #ifdef HAVE_TARGET_64_BIG
6053 template
6054 void
6055 Layout::add_to_gdb_index(bool is_type_unit,
6056 Sized_relobj<64, true>* object,
6057 const unsigned char* symbols,
6058 off_t symbols_size,
6059 unsigned int shndx,
6060 unsigned int reloc_shndx,
6061 unsigned int reloc_type);
6062 #endif
6063
6064 } // End namespace gold.
6065