PR gold/12675
[platform/upstream/binutils.git] / gold / layout.cc
1 // layout.cc -- lay out output file sections for gold
2
3 // Copyright 2006, 2007, 2008, 2009, 2010, 2011 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 "compressed_output.h"
48 #include "reduced_debug_output.h"
49 #include "object.h"
50 #include "reloc.h"
51 #include "descriptors.h"
52 #include "plugin.h"
53 #include "incremental.h"
54 #include "layout.h"
55
56 namespace gold
57 {
58
59 // Class Free_list.
60
61 // The total number of free lists used.
62 unsigned int Free_list::num_lists = 0;
63 // The total number of free list nodes used.
64 unsigned int Free_list::num_nodes = 0;
65 // The total number of calls to Free_list::remove.
66 unsigned int Free_list::num_removes = 0;
67 // The total number of nodes visited during calls to Free_list::remove.
68 unsigned int Free_list::num_remove_visits = 0;
69 // The total number of calls to Free_list::allocate.
70 unsigned int Free_list::num_allocates = 0;
71 // The total number of nodes visited during calls to Free_list::allocate.
72 unsigned int Free_list::num_allocate_visits = 0;
73
74 // Initialize the free list.  Creates a single free list node that
75 // describes the entire region of length LEN.  If EXTEND is true,
76 // allocate() is allowed to extend the region beyond its initial
77 // length.
78
79 void
80 Free_list::init(off_t len, bool extend)
81 {
82   this->list_.push_front(Free_list_node(0, len));
83   this->last_remove_ = this->list_.begin();
84   this->extend_ = extend;
85   this->length_ = len;
86   ++Free_list::num_lists;
87   ++Free_list::num_nodes;
88 }
89
90 // Remove a chunk from the free list.  Because we start with a single
91 // node that covers the entire section, and remove chunks from it one
92 // at a time, we do not need to coalesce chunks or handle cases that
93 // span more than one free node.  We expect to remove chunks from the
94 // free list in order, and we expect to have only a few chunks of free
95 // space left (corresponding to files that have changed since the last
96 // incremental link), so a simple linear list should provide sufficient
97 // performance.
98
99 void
100 Free_list::remove(off_t start, off_t end)
101 {
102   if (start == end)
103     return;
104   gold_assert(start < end);
105
106   ++Free_list::num_removes;
107
108   Iterator p = this->last_remove_;
109   if (p->start_ > start)
110     p = this->list_.begin();
111
112   for (; p != this->list_.end(); ++p)
113     {
114       ++Free_list::num_remove_visits;
115       // Find a node that wholly contains the indicated region.
116       if (p->start_ <= start && p->end_ >= end)
117         {
118           // Case 1: the indicated region spans the whole node.
119           // Add some fuzz to avoid creating tiny free chunks.
120           if (p->start_ + 3 >= start && p->end_ <= end + 3)
121             p = this->list_.erase(p);
122           // Case 2: remove a chunk from the start of the node.
123           else if (p->start_ + 3 >= start)
124             p->start_ = end;
125           // Case 3: remove a chunk from the end of the node.
126           else if (p->end_ <= end + 3)
127             p->end_ = start;
128           // Case 4: remove a chunk from the middle, and split
129           // the node into two.
130           else
131             {
132               Free_list_node newnode(p->start_, start);
133               p->start_ = end;
134               this->list_.insert(p, newnode);
135               ++Free_list::num_nodes;
136             }
137           this->last_remove_ = p;
138           return;
139         }
140     }
141
142   // Did not find a node containing the given chunk.  This could happen
143   // because a small chunk was already removed due to the fuzz.
144   gold_debug(DEBUG_INCREMENTAL,
145              "Free_list::remove(%d,%d) not found",
146              static_cast<int>(start), static_cast<int>(end));
147 }
148
149 // Allocate a chunk of size LEN from the free list.  Returns -1ULL
150 // if a sufficiently large chunk of free space is not found.
151 // We use a simple first-fit algorithm.
152
153 off_t
154 Free_list::allocate(off_t len, uint64_t align, off_t minoff)
155 {
156   gold_debug(DEBUG_INCREMENTAL,
157              "Free_list::allocate(%08lx, %d, %08lx)",
158              static_cast<long>(len), static_cast<int>(align),
159              static_cast<long>(minoff));
160   if (len == 0)
161     return align_address(minoff, align);
162
163   ++Free_list::num_allocates;
164
165   for (Iterator p = this->list_.begin(); p != this->list_.end(); ++p)
166     {
167       ++Free_list::num_allocate_visits;
168       off_t start = p->start_ > minoff ? p->start_ : minoff;
169       start = align_address(start, align);
170       off_t end = start + len;
171       if (end <= p->end_)
172         {
173           if (p->start_ + 3 >= start && p->end_ <= end + 3)
174             this->list_.erase(p);
175           else if (p->start_ + 3 >= start)
176             p->start_ = end;
177           else if (p->end_ <= end + 3)
178             p->end_ = start;
179           else
180             {
181               Free_list_node newnode(p->start_, start);
182               p->start_ = end;
183               this->list_.insert(p, newnode);
184               ++Free_list::num_nodes;
185             }
186           return start;
187         }
188     }
189   return -1;
190 }
191
192 // Dump the free list (for debugging).
193 void
194 Free_list::dump()
195 {
196   gold_info("Free list:\n     start      end   length\n");
197   for (Iterator p = this->list_.begin(); p != this->list_.end(); ++p)
198     gold_info("  %08lx %08lx %08lx", static_cast<long>(p->start_),
199               static_cast<long>(p->end_),
200               static_cast<long>(p->end_ - p->start_));
201 }
202
203 // Print the statistics for the free lists.
204 void
205 Free_list::print_stats()
206 {
207   fprintf(stderr, _("%s: total free lists: %u\n"),
208           program_name, Free_list::num_lists);
209   fprintf(stderr, _("%s: total free list nodes: %u\n"),
210           program_name, Free_list::num_nodes);
211   fprintf(stderr, _("%s: calls to Free_list::remove: %u\n"),
212           program_name, Free_list::num_removes);
213   fprintf(stderr, _("%s: nodes visited: %u\n"),
214           program_name, Free_list::num_remove_visits);
215   fprintf(stderr, _("%s: calls to Free_list::allocate: %u\n"),
216           program_name, Free_list::num_allocates);
217   fprintf(stderr, _("%s: nodes visited: %u\n"),
218           program_name, Free_list::num_allocate_visits);
219 }
220
221 // Layout::Relaxation_debug_check methods.
222
223 // Check that sections and special data are in reset states.
224 // We do not save states for Output_sections and special Output_data.
225 // So we check that they have not assigned any addresses or offsets.
226 // clean_up_after_relaxation simply resets their addresses and offsets.
227 void
228 Layout::Relaxation_debug_check::check_output_data_for_reset_values(
229     const Layout::Section_list& sections,
230     const Layout::Data_list& special_outputs)
231 {
232   for(Layout::Section_list::const_iterator p = sections.begin();
233       p != sections.end();
234       ++p)
235     gold_assert((*p)->address_and_file_offset_have_reset_values());
236
237   for(Layout::Data_list::const_iterator p = special_outputs.begin();
238       p != special_outputs.end();
239       ++p)
240     gold_assert((*p)->address_and_file_offset_have_reset_values());
241 }
242   
243 // Save information of SECTIONS for checking later.
244
245 void
246 Layout::Relaxation_debug_check::read_sections(
247     const Layout::Section_list& sections)
248 {
249   for(Layout::Section_list::const_iterator p = sections.begin();
250       p != sections.end();
251       ++p)
252     {
253       Output_section* os = *p;
254       Section_info info;
255       info.output_section = os;
256       info.address = os->is_address_valid() ? os->address() : 0;
257       info.data_size = os->is_data_size_valid() ? os->data_size() : -1;
258       info.offset = os->is_offset_valid()? os->offset() : -1 ;
259       this->section_infos_.push_back(info);
260     }
261 }
262
263 // Verify SECTIONS using previously recorded information.
264
265 void
266 Layout::Relaxation_debug_check::verify_sections(
267     const Layout::Section_list& sections)
268 {
269   size_t i = 0;
270   for(Layout::Section_list::const_iterator p = sections.begin();
271       p != sections.end();
272       ++p, ++i)
273     {
274       Output_section* os = *p;
275       uint64_t address = os->is_address_valid() ? os->address() : 0;
276       off_t data_size = os->is_data_size_valid() ? os->data_size() : -1;
277       off_t offset = os->is_offset_valid()? os->offset() : -1 ;
278
279       if (i >= this->section_infos_.size())
280         {
281           gold_fatal("Section_info of %s missing.\n", os->name());
282         }
283       const Section_info& info = this->section_infos_[i];
284       if (os != info.output_section)
285         gold_fatal("Section order changed.  Expecting %s but see %s\n",
286                    info.output_section->name(), os->name());
287       if (address != info.address
288           || data_size != info.data_size
289           || offset != info.offset)
290         gold_fatal("Section %s changed.\n", os->name());
291     }
292 }
293
294 // Layout_task_runner methods.
295
296 // Lay out the sections.  This is called after all the input objects
297 // have been read.
298
299 void
300 Layout_task_runner::run(Workqueue* workqueue, const Task* task)
301 {
302   Layout* layout = this->layout_;
303   off_t file_size = layout->finalize(this->input_objects_,
304                                      this->symtab_,
305                                      this->target_,
306                                      task);
307
308   // Now we know the final size of the output file and we know where
309   // each piece of information goes.
310
311   if (this->mapfile_ != NULL)
312     {
313       this->mapfile_->print_discarded_sections(this->input_objects_);
314       layout->print_to_mapfile(this->mapfile_);
315     }
316
317   Output_file* of;
318   if (layout->incremental_base() == NULL)
319     {
320       of = new Output_file(parameters->options().output_file_name());
321       if (this->options_.oformat_enum() != General_options::OBJECT_FORMAT_ELF)
322         of->set_is_temporary();
323       of->open(file_size);
324     }
325   else
326     {
327       of = layout->incremental_base()->output_file();
328
329       // Apply the incremental relocations for symbols whose values
330       // have changed.  We do this before we resize the file and start
331       // writing anything else to it, so that we can read the old
332       // incremental information from the file before (possibly)
333       // overwriting it.
334       if (parameters->incremental_update())
335         layout->incremental_base()->apply_incremental_relocs(this->symtab_,
336                                                              this->layout_,
337                                                              of);
338
339       of->resize(file_size);
340     }
341
342   // Queue up the final set of tasks.
343   gold::queue_final_tasks(this->options_, this->input_objects_,
344                           this->symtab_, layout, workqueue, of);
345 }
346
347 // Layout methods.
348
349 Layout::Layout(int number_of_input_files, Script_options* script_options)
350   : number_of_input_files_(number_of_input_files),
351     script_options_(script_options),
352     namepool_(),
353     sympool_(),
354     dynpool_(),
355     signatures_(),
356     section_name_map_(),
357     segment_list_(),
358     section_list_(),
359     unattached_section_list_(),
360     special_output_list_(),
361     section_headers_(NULL),
362     tls_segment_(NULL),
363     relro_segment_(NULL),
364     interp_segment_(NULL),
365     increase_relro_(0),
366     symtab_section_(NULL),
367     symtab_xindex_(NULL),
368     dynsym_section_(NULL),
369     dynsym_xindex_(NULL),
370     dynamic_section_(NULL),
371     dynamic_symbol_(NULL),
372     dynamic_data_(NULL),
373     eh_frame_section_(NULL),
374     eh_frame_data_(NULL),
375     added_eh_frame_data_(false),
376     eh_frame_hdr_section_(NULL),
377     build_id_note_(NULL),
378     debug_abbrev_(NULL),
379     debug_info_(NULL),
380     group_signatures_(),
381     output_file_size_(-1),
382     have_added_input_section_(false),
383     sections_are_attached_(false),
384     input_requires_executable_stack_(false),
385     input_with_gnu_stack_note_(false),
386     input_without_gnu_stack_note_(false),
387     has_static_tls_(false),
388     any_postprocessing_sections_(false),
389     resized_signatures_(false),
390     have_stabstr_section_(false),
391     incremental_inputs_(NULL),
392     record_output_section_data_from_script_(false),
393     script_output_section_data_list_(),
394     segment_states_(NULL),
395     relaxation_debug_check_(NULL),
396     incremental_base_(NULL),
397     free_list_()
398 {
399   // Make space for more than enough segments for a typical file.
400   // This is just for efficiency--it's OK if we wind up needing more.
401   this->segment_list_.reserve(12);
402
403   // We expect two unattached Output_data objects: the file header and
404   // the segment headers.
405   this->special_output_list_.reserve(2);
406
407   // Initialize structure needed for an incremental build.
408   if (parameters->incremental())
409     this->incremental_inputs_ = new Incremental_inputs;
410
411   // The section name pool is worth optimizing in all cases, because
412   // it is small, but there are often overlaps due to .rel sections.
413   this->namepool_.set_optimize();
414 }
415
416 // For incremental links, record the base file to be modified.
417
418 void
419 Layout::set_incremental_base(Incremental_binary* base)
420 {
421   this->incremental_base_ = base;
422   this->free_list_.init(base->output_file()->filesize(), true);
423 }
424
425 // Hash a key we use to look up an output section mapping.
426
427 size_t
428 Layout::Hash_key::operator()(const Layout::Key& k) const
429 {
430  return k.first + k.second.first + k.second.second;
431 }
432
433 // Returns whether the given section is in the list of
434 // debug-sections-used-by-some-version-of-gdb.  Currently,
435 // we've checked versions of gdb up to and including 6.7.1.
436
437 static const char* gdb_sections[] =
438 { ".debug_abbrev",
439   // ".debug_aranges",   // not used by gdb as of 6.7.1
440   ".debug_frame",
441   ".debug_info",
442   ".debug_types",
443   ".debug_line",
444   ".debug_loc",
445   ".debug_macinfo",
446   // ".debug_pubnames",  // not used by gdb as of 6.7.1
447   ".debug_ranges",
448   ".debug_str",
449 };
450
451 static const char* lines_only_debug_sections[] =
452 { ".debug_abbrev",
453   // ".debug_aranges",   // not used by gdb as of 6.7.1
454   // ".debug_frame",
455   ".debug_info",
456   // ".debug_types",
457   ".debug_line",
458   // ".debug_loc",
459   // ".debug_macinfo",
460   // ".debug_pubnames",  // not used by gdb as of 6.7.1
461   // ".debug_ranges",
462   ".debug_str",
463 };
464
465 static inline bool
466 is_gdb_debug_section(const char* str)
467 {
468   // We can do this faster: binary search or a hashtable.  But why bother?
469   for (size_t i = 0; i < sizeof(gdb_sections)/sizeof(*gdb_sections); ++i)
470     if (strcmp(str, gdb_sections[i]) == 0)
471       return true;
472   return false;
473 }
474
475 static inline bool
476 is_lines_only_debug_section(const char* str)
477 {
478   // We can do this faster: binary search or a hashtable.  But why bother?
479   for (size_t i = 0;
480        i < sizeof(lines_only_debug_sections)/sizeof(*lines_only_debug_sections);
481        ++i)
482     if (strcmp(str, lines_only_debug_sections[i]) == 0)
483       return true;
484   return false;
485 }
486
487 // Sometimes we compress sections.  This is typically done for
488 // sections that are not part of normal program execution (such as
489 // .debug_* sections), and where the readers of these sections know
490 // how to deal with compressed sections.  This routine doesn't say for
491 // certain whether we'll compress -- it depends on commandline options
492 // as well -- just whether this section is a candidate for compression.
493 // (The Output_compressed_section class decides whether to compress
494 // a given section, and picks the name of the compressed section.)
495
496 static bool
497 is_compressible_debug_section(const char* secname)
498 {
499   return (is_prefix_of(".debug", secname));
500 }
501
502 // We may see compressed debug sections in input files.  Return TRUE
503 // if this is the name of a compressed debug section.
504
505 bool
506 is_compressed_debug_section(const char* secname)
507 {
508   return (is_prefix_of(".zdebug", secname));
509 }
510
511 // Whether to include this section in the link.
512
513 template<int size, bool big_endian>
514 bool
515 Layout::include_section(Sized_relobj_file<size, big_endian>*, const char* name,
516                         const elfcpp::Shdr<size, big_endian>& shdr)
517 {
518   if (shdr.get_sh_flags() & elfcpp::SHF_EXCLUDE)
519     return false;
520
521   switch (shdr.get_sh_type())
522     {
523     case elfcpp::SHT_NULL:
524     case elfcpp::SHT_SYMTAB:
525     case elfcpp::SHT_DYNSYM:
526     case elfcpp::SHT_HASH:
527     case elfcpp::SHT_DYNAMIC:
528     case elfcpp::SHT_SYMTAB_SHNDX:
529       return false;
530
531     case elfcpp::SHT_STRTAB:
532       // Discard the sections which have special meanings in the ELF
533       // ABI.  Keep others (e.g., .stabstr).  We could also do this by
534       // checking the sh_link fields of the appropriate sections.
535       return (strcmp(name, ".dynstr") != 0
536               && strcmp(name, ".strtab") != 0
537               && strcmp(name, ".shstrtab") != 0);
538
539     case elfcpp::SHT_RELA:
540     case elfcpp::SHT_REL:
541     case elfcpp::SHT_GROUP:
542       // If we are emitting relocations these should be handled
543       // elsewhere.
544       gold_assert(!parameters->options().relocatable()
545                   && !parameters->options().emit_relocs());
546       return false;
547
548     case elfcpp::SHT_PROGBITS:
549       if (parameters->options().strip_debug()
550           && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
551         {
552           if (is_debug_info_section(name))
553             return false;
554         }
555       if (parameters->options().strip_debug_non_line()
556           && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
557         {
558           // Debugging sections can only be recognized by name.
559           if (is_prefix_of(".debug", name)
560               && !is_lines_only_debug_section(name))
561             return false;
562         }
563       if (parameters->options().strip_debug_gdb()
564           && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
565         {
566           // Debugging sections can only be recognized by name.
567           if (is_prefix_of(".debug", name)
568               && !is_gdb_debug_section(name))
569             return false;
570         }
571       if (parameters->options().strip_lto_sections()
572           && !parameters->options().relocatable()
573           && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
574         {
575           // Ignore LTO sections containing intermediate code.
576           if (is_prefix_of(".gnu.lto_", name))
577             return false;
578         }
579       // The GNU linker strips .gnu_debuglink sections, so we do too.
580       // This is a feature used to keep debugging information in
581       // separate files.
582       if (strcmp(name, ".gnu_debuglink") == 0)
583         return false;
584       return true;
585
586     default:
587       return true;
588     }
589 }
590
591 // Return an output section named NAME, or NULL if there is none.
592
593 Output_section*
594 Layout::find_output_section(const char* name) const
595 {
596   for (Section_list::const_iterator p = this->section_list_.begin();
597        p != this->section_list_.end();
598        ++p)
599     if (strcmp((*p)->name(), name) == 0)
600       return *p;
601   return NULL;
602 }
603
604 // Return an output segment of type TYPE, with segment flags SET set
605 // and segment flags CLEAR clear.  Return NULL if there is none.
606
607 Output_segment*
608 Layout::find_output_segment(elfcpp::PT type, elfcpp::Elf_Word set,
609                             elfcpp::Elf_Word clear) const
610 {
611   for (Segment_list::const_iterator p = this->segment_list_.begin();
612        p != this->segment_list_.end();
613        ++p)
614     if (static_cast<elfcpp::PT>((*p)->type()) == type
615         && ((*p)->flags() & set) == set
616         && ((*p)->flags() & clear) == 0)
617       return *p;
618   return NULL;
619 }
620
621 // When we put a .ctors or .dtors section with more than one word into
622 // a .init_array or .fini_array section, we need to reverse the words
623 // in the .ctors/.dtors section.  This is because .init_array executes
624 // constructors front to back, where .ctors executes them back to
625 // front, and vice-versa for .fini_array/.dtors.  Although we do want
626 // to remap .ctors/.dtors into .init_array/.fini_array because it can
627 // be more efficient, we don't want to change the order in which
628 // constructors/destructors are run.  This set just keeps track of
629 // these sections which need to be reversed.  It is only changed by
630 // Layout::layout.  It should be a private member of Layout, but that
631 // would require layout.h to #include object.h to get the definition
632 // of Section_id.
633 static Unordered_set<Section_id, Section_id_hash> ctors_sections_in_init_array;
634
635 // Return whether OBJECT/SHNDX is a .ctors/.dtors section mapped to a
636 // .init_array/.fini_array section.
637
638 bool
639 Layout::is_ctors_in_init_array(Relobj* relobj, unsigned int shndx) const
640 {
641   return (ctors_sections_in_init_array.find(Section_id(relobj, shndx))
642           != ctors_sections_in_init_array.end());
643 }
644
645 // Return the output section to use for section NAME with type TYPE
646 // and section flags FLAGS.  NAME must be canonicalized in the string
647 // pool, and NAME_KEY is the key.  ORDER is where this should appear
648 // in the output sections.  IS_RELRO is true for a relro section.
649
650 Output_section*
651 Layout::get_output_section(const char* name, Stringpool::Key name_key,
652                            elfcpp::Elf_Word type, elfcpp::Elf_Xword flags,
653                            Output_section_order order, bool is_relro)
654 {
655   elfcpp::Elf_Word lookup_type = type;
656
657   // For lookup purposes, treat INIT_ARRAY, FINI_ARRAY, and
658   // PREINIT_ARRAY like PROGBITS.  This ensures that we combine
659   // .init_array, .fini_array, and .preinit_array sections by name
660   // whatever their type in the input file.  We do this because the
661   // types are not always right in the input files.
662   if (lookup_type == elfcpp::SHT_INIT_ARRAY
663       || lookup_type == elfcpp::SHT_FINI_ARRAY
664       || lookup_type == elfcpp::SHT_PREINIT_ARRAY)
665     lookup_type = elfcpp::SHT_PROGBITS;
666
667   elfcpp::Elf_Xword lookup_flags = flags;
668
669   // Ignoring SHF_WRITE and SHF_EXECINSTR here means that we combine
670   // read-write with read-only sections.  Some other ELF linkers do
671   // not do this.  FIXME: Perhaps there should be an option
672   // controlling this.
673   lookup_flags &= ~(elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR);
674
675   const Key key(name_key, std::make_pair(lookup_type, lookup_flags));
676   const std::pair<Key, Output_section*> v(key, NULL);
677   std::pair<Section_name_map::iterator, bool> ins(
678     this->section_name_map_.insert(v));
679
680   if (!ins.second)
681     return ins.first->second;
682   else
683     {
684       // This is the first time we've seen this name/type/flags
685       // combination.  For compatibility with the GNU linker, we
686       // combine sections with contents and zero flags with sections
687       // with non-zero flags.  This is a workaround for cases where
688       // assembler code forgets to set section flags.  FIXME: Perhaps
689       // there should be an option to control this.
690       Output_section* os = NULL;
691
692       if (lookup_type == elfcpp::SHT_PROGBITS)
693         {
694           if (flags == 0)
695             {
696               Output_section* same_name = this->find_output_section(name);
697               if (same_name != NULL
698                   && (same_name->type() == elfcpp::SHT_PROGBITS
699                       || same_name->type() == elfcpp::SHT_INIT_ARRAY
700                       || same_name->type() == elfcpp::SHT_FINI_ARRAY
701                       || same_name->type() == elfcpp::SHT_PREINIT_ARRAY)
702                   && (same_name->flags() & elfcpp::SHF_TLS) == 0)
703                 os = same_name;
704             }
705           else if ((flags & elfcpp::SHF_TLS) == 0)
706             {
707               elfcpp::Elf_Xword zero_flags = 0;
708               const Key zero_key(name_key, std::make_pair(lookup_type,
709                                                           zero_flags));
710               Section_name_map::iterator p =
711                   this->section_name_map_.find(zero_key);
712               if (p != this->section_name_map_.end())
713                 os = p->second;
714             }
715         }
716
717       if (os == NULL)
718         os = this->make_output_section(name, type, flags, order, is_relro);
719
720       ins.first->second = os;
721       return os;
722     }
723 }
724
725 // Pick the output section to use for section NAME, in input file
726 // RELOBJ, with type TYPE and flags FLAGS.  RELOBJ may be NULL for a
727 // linker created section.  IS_INPUT_SECTION is true if we are
728 // choosing an output section for an input section found in a input
729 // file.  ORDER is where this section should appear in the output
730 // sections.  IS_RELRO is true for a relro section.  This will return
731 // NULL if the input section should be discarded.
732
733 Output_section*
734 Layout::choose_output_section(const Relobj* relobj, const char* name,
735                               elfcpp::Elf_Word type, elfcpp::Elf_Xword flags,
736                               bool is_input_section, Output_section_order order,
737                               bool is_relro)
738 {
739   // We should not see any input sections after we have attached
740   // sections to segments.
741   gold_assert(!is_input_section || !this->sections_are_attached_);
742
743   // Some flags in the input section should not be automatically
744   // copied to the output section.
745   flags &= ~ (elfcpp::SHF_INFO_LINK
746               | elfcpp::SHF_GROUP
747               | elfcpp::SHF_MERGE
748               | elfcpp::SHF_STRINGS);
749
750   // We only clear the SHF_LINK_ORDER flag in for
751   // a non-relocatable link.
752   if (!parameters->options().relocatable())
753     flags &= ~elfcpp::SHF_LINK_ORDER;
754
755   if (this->script_options_->saw_sections_clause())
756     {
757       // We are using a SECTIONS clause, so the output section is
758       // chosen based only on the name.
759
760       Script_sections* ss = this->script_options_->script_sections();
761       const char* file_name = relobj == NULL ? NULL : relobj->name().c_str();
762       Output_section** output_section_slot;
763       Script_sections::Section_type script_section_type;
764       const char* orig_name = name;
765       name = ss->output_section_name(file_name, name, &output_section_slot,
766                                      &script_section_type);
767       if (name == NULL)
768         {
769           gold_debug(DEBUG_SCRIPT, _("Unable to create output section '%s' "
770                                      "because it is not allowed by the "
771                                      "SECTIONS clause of the linker script"),
772                      orig_name);
773           // The SECTIONS clause says to discard this input section.
774           return NULL;
775         }
776
777       // We can only handle script section types ST_NONE and ST_NOLOAD.
778       switch (script_section_type)
779         {
780         case Script_sections::ST_NONE:
781           break;
782         case Script_sections::ST_NOLOAD:
783           flags &= elfcpp::SHF_ALLOC;
784           break;
785         default:
786           gold_unreachable();
787         }
788
789       // If this is an orphan section--one not mentioned in the linker
790       // script--then OUTPUT_SECTION_SLOT will be NULL, and we do the
791       // default processing below.
792
793       if (output_section_slot != NULL)
794         {
795           if (*output_section_slot != NULL)
796             {
797               (*output_section_slot)->update_flags_for_input_section(flags);
798               return *output_section_slot;
799             }
800
801           // We don't put sections found in the linker script into
802           // SECTION_NAME_MAP_.  That keeps us from getting confused
803           // if an orphan section is mapped to a section with the same
804           // name as one in the linker script.
805
806           name = this->namepool_.add(name, false, NULL);
807
808           Output_section* os = this->make_output_section(name, type, flags,
809                                                          order, is_relro);
810
811           os->set_found_in_sections_clause();
812
813           // Special handling for NOLOAD sections.
814           if (script_section_type == Script_sections::ST_NOLOAD)
815             {
816               os->set_is_noload();
817
818               // The constructor of Output_section sets addresses of non-ALLOC
819               // sections to 0 by default.  We don't want that for NOLOAD
820               // sections even if they have no SHF_ALLOC flag.
821               if ((os->flags() & elfcpp::SHF_ALLOC) == 0
822                   && os->is_address_valid())
823                 {
824                   gold_assert(os->address() == 0
825                               && !os->is_offset_valid()
826                               && !os->is_data_size_valid());
827                   os->reset_address_and_file_offset();
828                 }
829             }
830
831           *output_section_slot = os;
832           return os;
833         }
834     }
835
836   // FIXME: Handle SHF_OS_NONCONFORMING somewhere.
837
838   size_t len = strlen(name);
839   char* uncompressed_name = NULL;
840
841   // Compressed debug sections should be mapped to the corresponding
842   // uncompressed section.
843   if (is_compressed_debug_section(name))
844     {
845       uncompressed_name = new char[len];
846       uncompressed_name[0] = '.';
847       gold_assert(name[0] == '.' && name[1] == 'z');
848       strncpy(&uncompressed_name[1], &name[2], len - 2);
849       uncompressed_name[len - 1] = '\0';
850       len -= 1;
851       name = uncompressed_name;
852     }
853
854   // Turn NAME from the name of the input section into the name of the
855   // output section.
856   if (is_input_section
857       && !this->script_options_->saw_sections_clause()
858       && !parameters->options().relocatable())
859     name = Layout::output_section_name(relobj, name, &len);
860
861   Stringpool::Key name_key;
862   name = this->namepool_.add_with_length(name, len, true, &name_key);
863
864   if (uncompressed_name != NULL)
865     delete[] uncompressed_name;
866
867   // Find or make the output section.  The output section is selected
868   // based on the section name, type, and flags.
869   return this->get_output_section(name, name_key, type, flags, order, is_relro);
870 }
871
872 // For incremental links, record the initial fixed layout of a section
873 // from the base file, and return a pointer to the Output_section.
874
875 template<int size, bool big_endian>
876 Output_section*
877 Layout::init_fixed_output_section(const char* name,
878                                   elfcpp::Shdr<size, big_endian>& shdr)
879 {
880   unsigned int sh_type = shdr.get_sh_type();
881
882   // We preserve the layout of PROGBITS, NOBITS, and NOTE sections.
883   // All others will be created from scratch and reallocated.
884   if (sh_type != elfcpp::SHT_PROGBITS
885       && sh_type != elfcpp::SHT_NOBITS
886       && sh_type != elfcpp::SHT_NOTE)
887     return NULL;
888
889   typename elfcpp::Elf_types<size>::Elf_Addr sh_addr = shdr.get_sh_addr();
890   typename elfcpp::Elf_types<size>::Elf_Off sh_offset = shdr.get_sh_offset();
891   typename elfcpp::Elf_types<size>::Elf_WXword sh_size = shdr.get_sh_size();
892   typename elfcpp::Elf_types<size>::Elf_WXword sh_flags = shdr.get_sh_flags();
893   typename elfcpp::Elf_types<size>::Elf_WXword sh_addralign =
894       shdr.get_sh_addralign();
895
896   // Make the output section.
897   Stringpool::Key name_key;
898   name = this->namepool_.add(name, true, &name_key);
899   Output_section* os = this->get_output_section(name, name_key, sh_type,
900                                                 sh_flags, ORDER_INVALID, false);
901   os->set_fixed_layout(sh_addr, sh_offset, sh_size, sh_addralign);
902   if (sh_type != elfcpp::SHT_NOBITS)
903     this->free_list_.remove(sh_offset, sh_offset + sh_size);
904   return os;
905 }
906
907 // Return the output section to use for input section SHNDX, with name
908 // NAME, with header HEADER, from object OBJECT.  RELOC_SHNDX is the
909 // index of a relocation section which applies to this section, or 0
910 // if none, or -1U if more than one.  RELOC_TYPE is the type of the
911 // relocation section if there is one.  Set *OFF to the offset of this
912 // input section without the output section.  Return NULL if the
913 // section should be discarded.  Set *OFF to -1 if the section
914 // contents should not be written directly to the output file, but
915 // will instead receive special handling.
916
917 template<int size, bool big_endian>
918 Output_section*
919 Layout::layout(Sized_relobj_file<size, big_endian>* object, unsigned int shndx,
920                const char* name, const elfcpp::Shdr<size, big_endian>& shdr,
921                unsigned int reloc_shndx, unsigned int, off_t* off)
922 {
923   *off = 0;
924
925   if (!this->include_section(object, name, shdr))
926     return NULL;
927
928   elfcpp::Elf_Word sh_type = shdr.get_sh_type();
929
930   // In a relocatable link a grouped section must not be combined with
931   // any other sections.
932   Output_section* os;
933   if (parameters->options().relocatable()
934       && (shdr.get_sh_flags() & elfcpp::SHF_GROUP) != 0)
935     {
936       name = this->namepool_.add(name, true, NULL);
937       os = this->make_output_section(name, sh_type, shdr.get_sh_flags(),
938                                      ORDER_INVALID, false);
939     }
940   else
941     {
942       os = this->choose_output_section(object, name, sh_type,
943                                        shdr.get_sh_flags(), true,
944                                        ORDER_INVALID, false);
945       if (os == NULL)
946         return NULL;
947     }
948
949   // By default the GNU linker sorts input sections whose names match
950   // .ctors.*, .dtors.*, .init_array.*, or .fini_array.*.  The
951   // sections are sorted by name.  This is used to implement
952   // constructor priority ordering.  We are compatible.  When we put
953   // .ctor sections in .init_array and .dtor sections in .fini_array,
954   // we must also sort plain .ctor and .dtor sections.
955   if (!this->script_options_->saw_sections_clause()
956       && !parameters->options().relocatable()
957       && (is_prefix_of(".ctors.", name)
958           || is_prefix_of(".dtors.", name)
959           || is_prefix_of(".init_array.", name)
960           || is_prefix_of(".fini_array.", name)
961           || (parameters->options().ctors_in_init_array()
962               && (strcmp(name, ".ctors") == 0
963                   || strcmp(name, ".dtors") == 0))))
964     os->set_must_sort_attached_input_sections();
965
966   // If this is a .ctors or .ctors.* section being mapped to a
967   // .init_array section, or a .dtors or .dtors.* section being mapped
968   // to a .fini_array section, we will need to reverse the words if
969   // there is more than one.  Record this section for later.  See
970   // ctors_sections_in_init_array above.
971   if (!this->script_options_->saw_sections_clause()
972       && !parameters->options().relocatable()
973       && shdr.get_sh_size() > size / 8
974       && (((strcmp(name, ".ctors") == 0
975             || is_prefix_of(".ctors.", name))
976            && strcmp(os->name(), ".init_array") == 0)
977           || ((strcmp(name, ".dtors") == 0
978                || is_prefix_of(".dtors.", name))
979               && strcmp(os->name(), ".fini_array") == 0)))
980     ctors_sections_in_init_array.insert(Section_id(object, shndx));
981
982   // FIXME: Handle SHF_LINK_ORDER somewhere.
983
984   elfcpp::Elf_Xword orig_flags = os->flags();
985
986   *off = os->add_input_section(this, object, shndx, name, shdr, reloc_shndx,
987                                this->script_options_->saw_sections_clause());
988
989   // If the flags changed, we may have to change the order.
990   if ((orig_flags & elfcpp::SHF_ALLOC) != 0)
991     {
992       orig_flags &= (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR);
993       elfcpp::Elf_Xword new_flags =
994         os->flags() & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR);
995       if (orig_flags != new_flags)
996         os->set_order(this->default_section_order(os, false));
997     }
998
999   this->have_added_input_section_ = true;
1000
1001   return os;
1002 }
1003
1004 // Handle a relocation section when doing a relocatable link.
1005
1006 template<int size, bool big_endian>
1007 Output_section*
1008 Layout::layout_reloc(Sized_relobj_file<size, big_endian>* object,
1009                      unsigned int,
1010                      const elfcpp::Shdr<size, big_endian>& shdr,
1011                      Output_section* data_section,
1012                      Relocatable_relocs* rr)
1013 {
1014   gold_assert(parameters->options().relocatable()
1015               || parameters->options().emit_relocs());
1016
1017   int sh_type = shdr.get_sh_type();
1018
1019   std::string name;
1020   if (sh_type == elfcpp::SHT_REL)
1021     name = ".rel";
1022   else if (sh_type == elfcpp::SHT_RELA)
1023     name = ".rela";
1024   else
1025     gold_unreachable();
1026   name += data_section->name();
1027
1028   // In a relocatable link relocs for a grouped section must not be
1029   // combined with other reloc sections.
1030   Output_section* os;
1031   if (!parameters->options().relocatable()
1032       || (data_section->flags() & elfcpp::SHF_GROUP) == 0)
1033     os = this->choose_output_section(object, name.c_str(), sh_type,
1034                                      shdr.get_sh_flags(), false,
1035                                      ORDER_INVALID, false);
1036   else
1037     {
1038       const char* n = this->namepool_.add(name.c_str(), true, NULL);
1039       os = this->make_output_section(n, sh_type, shdr.get_sh_flags(),
1040                                      ORDER_INVALID, false);
1041     }
1042
1043   os->set_should_link_to_symtab();
1044   os->set_info_section(data_section);
1045
1046   Output_section_data* posd;
1047   if (sh_type == elfcpp::SHT_REL)
1048     {
1049       os->set_entsize(elfcpp::Elf_sizes<size>::rel_size);
1050       posd = new Output_relocatable_relocs<elfcpp::SHT_REL,
1051                                            size,
1052                                            big_endian>(rr);
1053     }
1054   else if (sh_type == elfcpp::SHT_RELA)
1055     {
1056       os->set_entsize(elfcpp::Elf_sizes<size>::rela_size);
1057       posd = new Output_relocatable_relocs<elfcpp::SHT_RELA,
1058                                            size,
1059                                            big_endian>(rr);
1060     }
1061   else
1062     gold_unreachable();
1063
1064   os->add_output_section_data(posd);
1065   rr->set_output_data(posd);
1066
1067   return os;
1068 }
1069
1070 // Handle a group section when doing a relocatable link.
1071
1072 template<int size, bool big_endian>
1073 void
1074 Layout::layout_group(Symbol_table* symtab,
1075                      Sized_relobj_file<size, big_endian>* object,
1076                      unsigned int,
1077                      const char* group_section_name,
1078                      const char* signature,
1079                      const elfcpp::Shdr<size, big_endian>& shdr,
1080                      elfcpp::Elf_Word flags,
1081                      std::vector<unsigned int>* shndxes)
1082 {
1083   gold_assert(parameters->options().relocatable());
1084   gold_assert(shdr.get_sh_type() == elfcpp::SHT_GROUP);
1085   group_section_name = this->namepool_.add(group_section_name, true, NULL);
1086   Output_section* os = this->make_output_section(group_section_name,
1087                                                  elfcpp::SHT_GROUP,
1088                                                  shdr.get_sh_flags(),
1089                                                  ORDER_INVALID, false);
1090
1091   // We need to find a symbol with the signature in the symbol table.
1092   // If we don't find one now, we need to look again later.
1093   Symbol* sym = symtab->lookup(signature, NULL);
1094   if (sym != NULL)
1095     os->set_info_symndx(sym);
1096   else
1097     {
1098       // Reserve some space to minimize reallocations.
1099       if (this->group_signatures_.empty())
1100         this->group_signatures_.reserve(this->number_of_input_files_ * 16);
1101
1102       // We will wind up using a symbol whose name is the signature.
1103       // So just put the signature in the symbol name pool to save it.
1104       signature = symtab->canonicalize_name(signature);
1105       this->group_signatures_.push_back(Group_signature(os, signature));
1106     }
1107
1108   os->set_should_link_to_symtab();
1109   os->set_entsize(4);
1110
1111   section_size_type entry_count =
1112     convert_to_section_size_type(shdr.get_sh_size() / 4);
1113   Output_section_data* posd =
1114     new Output_data_group<size, big_endian>(object, entry_count, flags,
1115                                             shndxes);
1116   os->add_output_section_data(posd);
1117 }
1118
1119 // Special GNU handling of sections name .eh_frame.  They will
1120 // normally hold exception frame data as defined by the C++ ABI
1121 // (http://codesourcery.com/cxx-abi/).
1122
1123 template<int size, bool big_endian>
1124 Output_section*
1125 Layout::layout_eh_frame(Sized_relobj_file<size, big_endian>* object,
1126                         const unsigned char* symbols,
1127                         off_t symbols_size,
1128                         const unsigned char* symbol_names,
1129                         off_t symbol_names_size,
1130                         unsigned int shndx,
1131                         const elfcpp::Shdr<size, big_endian>& shdr,
1132                         unsigned int reloc_shndx, unsigned int reloc_type,
1133                         off_t* off)
1134 {
1135   gold_assert(shdr.get_sh_type() == elfcpp::SHT_PROGBITS
1136               || shdr.get_sh_type() == elfcpp::SHT_X86_64_UNWIND);
1137   gold_assert((shdr.get_sh_flags() & elfcpp::SHF_ALLOC) != 0);
1138
1139   const char* const name = ".eh_frame";
1140   Output_section* os = this->choose_output_section(object, name,
1141                                                    elfcpp::SHT_PROGBITS,
1142                                                    elfcpp::SHF_ALLOC, false,
1143                                                    ORDER_EHFRAME, false);
1144   if (os == NULL)
1145     return NULL;
1146
1147   if (this->eh_frame_section_ == NULL)
1148     {
1149       this->eh_frame_section_ = os;
1150       this->eh_frame_data_ = new Eh_frame();
1151
1152       // For incremental linking, we do not optimize .eh_frame sections
1153       // or create a .eh_frame_hdr section.
1154       if (parameters->options().eh_frame_hdr() && !parameters->incremental())
1155         {
1156           Output_section* hdr_os =
1157             this->choose_output_section(NULL, ".eh_frame_hdr",
1158                                         elfcpp::SHT_PROGBITS,
1159                                         elfcpp::SHF_ALLOC, false,
1160                                         ORDER_EHFRAME, false);
1161
1162           if (hdr_os != NULL)
1163             {
1164               Eh_frame_hdr* hdr_posd = new Eh_frame_hdr(os,
1165                                                         this->eh_frame_data_);
1166               hdr_os->add_output_section_data(hdr_posd);
1167
1168               hdr_os->set_after_input_sections();
1169
1170               if (!this->script_options_->saw_phdrs_clause())
1171                 {
1172                   Output_segment* hdr_oseg;
1173                   hdr_oseg = this->make_output_segment(elfcpp::PT_GNU_EH_FRAME,
1174                                                        elfcpp::PF_R);
1175                   hdr_oseg->add_output_section_to_nonload(hdr_os,
1176                                                           elfcpp::PF_R);
1177                 }
1178
1179               this->eh_frame_data_->set_eh_frame_hdr(hdr_posd);
1180             }
1181         }
1182     }
1183
1184   gold_assert(this->eh_frame_section_ == os);
1185
1186   elfcpp::Elf_Xword orig_flags = os->flags();
1187
1188   if (!parameters->incremental()
1189       && this->eh_frame_data_->add_ehframe_input_section(object,
1190                                                          symbols,
1191                                                          symbols_size,
1192                                                          symbol_names,
1193                                                          symbol_names_size,
1194                                                          shndx,
1195                                                          reloc_shndx,
1196                                                          reloc_type))
1197     {
1198       os->update_flags_for_input_section(shdr.get_sh_flags());
1199
1200       // A writable .eh_frame section is a RELRO section.
1201       if ((orig_flags & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR))
1202           != (os->flags() & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR)))
1203         {
1204           os->set_is_relro();
1205           os->set_order(ORDER_RELRO);
1206         }
1207
1208       // We found a .eh_frame section we are going to optimize, so now
1209       // we can add the set of optimized sections to the output
1210       // section.  We need to postpone adding this until we've found a
1211       // section we can optimize so that the .eh_frame section in
1212       // crtbegin.o winds up at the start of the output section.
1213       if (!this->added_eh_frame_data_)
1214         {
1215           os->add_output_section_data(this->eh_frame_data_);
1216           this->added_eh_frame_data_ = true;
1217         }
1218       *off = -1;
1219     }
1220   else
1221     {
1222       // We couldn't handle this .eh_frame section for some reason.
1223       // Add it as a normal section.
1224       bool saw_sections_clause = this->script_options_->saw_sections_clause();
1225       *off = os->add_input_section(this, object, shndx, name, shdr, reloc_shndx,
1226                                    saw_sections_clause);
1227       this->have_added_input_section_ = true;
1228
1229       if ((orig_flags & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR))
1230           != (os->flags() & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR)))
1231         os->set_order(this->default_section_order(os, false));
1232     }
1233
1234   return os;
1235 }
1236
1237 // Add POSD to an output section using NAME, TYPE, and FLAGS.  Return
1238 // the output section.
1239
1240 Output_section*
1241 Layout::add_output_section_data(const char* name, elfcpp::Elf_Word type,
1242                                 elfcpp::Elf_Xword flags,
1243                                 Output_section_data* posd,
1244                                 Output_section_order order, bool is_relro)
1245 {
1246   Output_section* os = this->choose_output_section(NULL, name, type, flags,
1247                                                    false, order, is_relro);
1248   if (os != NULL)
1249     os->add_output_section_data(posd);
1250   return os;
1251 }
1252
1253 // Map section flags to segment flags.
1254
1255 elfcpp::Elf_Word
1256 Layout::section_flags_to_segment(elfcpp::Elf_Xword flags)
1257 {
1258   elfcpp::Elf_Word ret = elfcpp::PF_R;
1259   if ((flags & elfcpp::SHF_WRITE) != 0)
1260     ret |= elfcpp::PF_W;
1261   if ((flags & elfcpp::SHF_EXECINSTR) != 0)
1262     ret |= elfcpp::PF_X;
1263   return ret;
1264 }
1265
1266 // Make a new Output_section, and attach it to segments as
1267 // appropriate.  ORDER is the order in which this section should
1268 // appear in the output segment.  IS_RELRO is true if this is a relro
1269 // (read-only after relocations) section.
1270
1271 Output_section*
1272 Layout::make_output_section(const char* name, elfcpp::Elf_Word type,
1273                             elfcpp::Elf_Xword flags,
1274                             Output_section_order order, bool is_relro)
1275 {
1276   Output_section* os;
1277   if ((flags & elfcpp::SHF_ALLOC) == 0
1278       && strcmp(parameters->options().compress_debug_sections(), "none") != 0
1279       && is_compressible_debug_section(name))
1280     os = new Output_compressed_section(&parameters->options(), name, type,
1281                                        flags);
1282   else if ((flags & elfcpp::SHF_ALLOC) == 0
1283            && parameters->options().strip_debug_non_line()
1284            && strcmp(".debug_abbrev", name) == 0)
1285     {
1286       os = this->debug_abbrev_ = new Output_reduced_debug_abbrev_section(
1287           name, type, flags);
1288       if (this->debug_info_)
1289         this->debug_info_->set_abbreviations(this->debug_abbrev_);
1290     }
1291   else if ((flags & elfcpp::SHF_ALLOC) == 0
1292            && parameters->options().strip_debug_non_line()
1293            && strcmp(".debug_info", name) == 0)
1294     {
1295       os = this->debug_info_ = new Output_reduced_debug_info_section(
1296           name, type, flags);
1297       if (this->debug_abbrev_)
1298         this->debug_info_->set_abbreviations(this->debug_abbrev_);
1299     }
1300   else
1301     {
1302       // Sometimes .init_array*, .preinit_array* and .fini_array* do
1303       // not have correct section types.  Force them here.
1304       if (type == elfcpp::SHT_PROGBITS)
1305         {
1306           if (is_prefix_of(".init_array", name))
1307             type = elfcpp::SHT_INIT_ARRAY;
1308           else if (is_prefix_of(".preinit_array", name))
1309             type = elfcpp::SHT_PREINIT_ARRAY;
1310           else if (is_prefix_of(".fini_array", name))
1311             type = elfcpp::SHT_FINI_ARRAY;
1312         }
1313
1314       // FIXME: const_cast is ugly.
1315       Target* target = const_cast<Target*>(&parameters->target());
1316       os = target->make_output_section(name, type, flags);
1317     }
1318
1319   // With -z relro, we have to recognize the special sections by name.
1320   // There is no other way.
1321   bool is_relro_local = false;
1322   if (!this->script_options_->saw_sections_clause()
1323       && parameters->options().relro()
1324       && type == elfcpp::SHT_PROGBITS
1325       && (flags & elfcpp::SHF_ALLOC) != 0
1326       && (flags & elfcpp::SHF_WRITE) != 0)
1327     {
1328       if (strcmp(name, ".data.rel.ro") == 0)
1329         is_relro = true;
1330       else if (strcmp(name, ".data.rel.ro.local") == 0)
1331         {
1332           is_relro = true;
1333           is_relro_local = true;
1334         }
1335       else if (type == elfcpp::SHT_INIT_ARRAY
1336                || type == elfcpp::SHT_FINI_ARRAY
1337                || type == elfcpp::SHT_PREINIT_ARRAY)
1338         is_relro = true;
1339       else if (strcmp(name, ".ctors") == 0
1340                || strcmp(name, ".dtors") == 0
1341                || strcmp(name, ".jcr") == 0)
1342         is_relro = true;
1343     }
1344
1345   if (is_relro)
1346     os->set_is_relro();
1347
1348   if (order == ORDER_INVALID && (flags & elfcpp::SHF_ALLOC) != 0)
1349     order = this->default_section_order(os, is_relro_local);
1350
1351   os->set_order(order);
1352
1353   parameters->target().new_output_section(os);
1354
1355   this->section_list_.push_back(os);
1356
1357   // The GNU linker by default sorts some sections by priority, so we
1358   // do the same.  We need to know that this might happen before we
1359   // attach any input sections.
1360   if (!this->script_options_->saw_sections_clause()
1361       && !parameters->options().relocatable()
1362       && (strcmp(name, ".init_array") == 0
1363           || strcmp(name, ".fini_array") == 0
1364           || (!parameters->options().ctors_in_init_array()
1365               && (strcmp(name, ".ctors") == 0
1366                   || strcmp(name, ".dtors") == 0))))
1367     os->set_may_sort_attached_input_sections();
1368
1369   // Check for .stab*str sections, as .stab* sections need to link to
1370   // them.
1371   if (type == elfcpp::SHT_STRTAB
1372       && !this->have_stabstr_section_
1373       && strncmp(name, ".stab", 5) == 0
1374       && strcmp(name + strlen(name) - 3, "str") == 0)
1375     this->have_stabstr_section_ = true;
1376
1377   // If we have already attached the sections to segments, then we
1378   // need to attach this one now.  This happens for sections created
1379   // directly by the linker.
1380   if (this->sections_are_attached_)
1381     this->attach_section_to_segment(os);
1382
1383   return os;
1384 }
1385
1386 // Return the default order in which a section should be placed in an
1387 // output segment.  This function captures a lot of the ideas in
1388 // ld/scripttempl/elf.sc in the GNU linker.  Note that the order of a
1389 // linker created section is normally set when the section is created;
1390 // this function is used for input sections.
1391
1392 Output_section_order
1393 Layout::default_section_order(Output_section* os, bool is_relro_local)
1394 {
1395   gold_assert((os->flags() & elfcpp::SHF_ALLOC) != 0);
1396   bool is_write = (os->flags() & elfcpp::SHF_WRITE) != 0;
1397   bool is_execinstr = (os->flags() & elfcpp::SHF_EXECINSTR) != 0;
1398   bool is_bss = false;
1399
1400   switch (os->type())
1401     {
1402     default:
1403     case elfcpp::SHT_PROGBITS:
1404       break;
1405     case elfcpp::SHT_NOBITS:
1406       is_bss = true;
1407       break;
1408     case elfcpp::SHT_RELA:
1409     case elfcpp::SHT_REL:
1410       if (!is_write)
1411         return ORDER_DYNAMIC_RELOCS;
1412       break;
1413     case elfcpp::SHT_HASH:
1414     case elfcpp::SHT_DYNAMIC:
1415     case elfcpp::SHT_SHLIB:
1416     case elfcpp::SHT_DYNSYM:
1417     case elfcpp::SHT_GNU_HASH:
1418     case elfcpp::SHT_GNU_verdef:
1419     case elfcpp::SHT_GNU_verneed:
1420     case elfcpp::SHT_GNU_versym:
1421       if (!is_write)
1422         return ORDER_DYNAMIC_LINKER;
1423       break;
1424     case elfcpp::SHT_NOTE:
1425       return is_write ? ORDER_RW_NOTE : ORDER_RO_NOTE;
1426     }
1427
1428   if ((os->flags() & elfcpp::SHF_TLS) != 0)
1429     return is_bss ? ORDER_TLS_BSS : ORDER_TLS_DATA;
1430
1431   if (!is_bss && !is_write)
1432     {
1433       if (is_execinstr)
1434         {
1435           if (strcmp(os->name(), ".init") == 0)
1436             return ORDER_INIT;
1437           else if (strcmp(os->name(), ".fini") == 0)
1438             return ORDER_FINI;
1439         }
1440       return is_execinstr ? ORDER_TEXT : ORDER_READONLY;
1441     }
1442
1443   if (os->is_relro())
1444     return is_relro_local ? ORDER_RELRO_LOCAL : ORDER_RELRO;
1445
1446   if (os->is_small_section())
1447     return is_bss ? ORDER_SMALL_BSS : ORDER_SMALL_DATA;
1448   if (os->is_large_section())
1449     return is_bss ? ORDER_LARGE_BSS : ORDER_LARGE_DATA;
1450
1451   return is_bss ? ORDER_BSS : ORDER_DATA;
1452 }
1453
1454 // Attach output sections to segments.  This is called after we have
1455 // seen all the input sections.
1456
1457 void
1458 Layout::attach_sections_to_segments()
1459 {
1460   for (Section_list::iterator p = this->section_list_.begin();
1461        p != this->section_list_.end();
1462        ++p)
1463     this->attach_section_to_segment(*p);
1464
1465   this->sections_are_attached_ = true;
1466 }
1467
1468 // Attach an output section to a segment.
1469
1470 void
1471 Layout::attach_section_to_segment(Output_section* os)
1472 {
1473   if ((os->flags() & elfcpp::SHF_ALLOC) == 0)
1474     this->unattached_section_list_.push_back(os);
1475   else
1476     this->attach_allocated_section_to_segment(os);
1477 }
1478
1479 // Attach an allocated output section to a segment.
1480
1481 void
1482 Layout::attach_allocated_section_to_segment(Output_section* os)
1483 {
1484   elfcpp::Elf_Xword flags = os->flags();
1485   gold_assert((flags & elfcpp::SHF_ALLOC) != 0);
1486
1487   if (parameters->options().relocatable())
1488     return;
1489
1490   // If we have a SECTIONS clause, we can't handle the attachment to
1491   // segments until after we've seen all the sections.
1492   if (this->script_options_->saw_sections_clause())
1493     return;
1494
1495   gold_assert(!this->script_options_->saw_phdrs_clause());
1496
1497   // This output section goes into a PT_LOAD segment.
1498
1499   elfcpp::Elf_Word seg_flags = Layout::section_flags_to_segment(flags);
1500
1501   // Check for --section-start.
1502   uint64_t addr;
1503   bool is_address_set = parameters->options().section_start(os->name(), &addr);
1504
1505   // In general the only thing we really care about for PT_LOAD
1506   // segments is whether or not they are writable or executable,
1507   // so that is how we search for them.
1508   // Large data sections also go into their own PT_LOAD segment.
1509   // People who need segments sorted on some other basis will
1510   // have to use a linker script.
1511
1512   Segment_list::const_iterator p;
1513   for (p = this->segment_list_.begin();
1514        p != this->segment_list_.end();
1515        ++p)
1516     {
1517       if ((*p)->type() != elfcpp::PT_LOAD)
1518         continue;
1519       if (!parameters->options().omagic()
1520           && ((*p)->flags() & elfcpp::PF_W) != (seg_flags & elfcpp::PF_W))
1521         continue;
1522       if (parameters->options().rosegment()
1523           && ((*p)->flags() & elfcpp::PF_X) != (seg_flags & elfcpp::PF_X))
1524         continue;
1525       // If -Tbss was specified, we need to separate the data and BSS
1526       // segments.
1527       if (parameters->options().user_set_Tbss())
1528         {
1529           if ((os->type() == elfcpp::SHT_NOBITS)
1530               == (*p)->has_any_data_sections())
1531             continue;
1532         }
1533       if (os->is_large_data_section() && !(*p)->is_large_data_segment())
1534         continue;
1535
1536       if (is_address_set)
1537         {
1538           if ((*p)->are_addresses_set())
1539             continue;
1540
1541           (*p)->add_initial_output_data(os);
1542           (*p)->update_flags_for_output_section(seg_flags);
1543           (*p)->set_addresses(addr, addr);
1544           break;
1545         }
1546
1547       (*p)->add_output_section_to_load(this, os, seg_flags);
1548       break;
1549     }
1550
1551   if (p == this->segment_list_.end())
1552     {
1553       Output_segment* oseg = this->make_output_segment(elfcpp::PT_LOAD,
1554                                                        seg_flags);
1555       if (os->is_large_data_section())
1556         oseg->set_is_large_data_segment();
1557       oseg->add_output_section_to_load(this, os, seg_flags);
1558       if (is_address_set)
1559         oseg->set_addresses(addr, addr);
1560     }
1561
1562   // If we see a loadable SHT_NOTE section, we create a PT_NOTE
1563   // segment.
1564   if (os->type() == elfcpp::SHT_NOTE)
1565     {
1566       // See if we already have an equivalent PT_NOTE segment.
1567       for (p = this->segment_list_.begin();
1568            p != segment_list_.end();
1569            ++p)
1570         {
1571           if ((*p)->type() == elfcpp::PT_NOTE
1572               && (((*p)->flags() & elfcpp::PF_W)
1573                   == (seg_flags & elfcpp::PF_W)))
1574             {
1575               (*p)->add_output_section_to_nonload(os, seg_flags);
1576               break;
1577             }
1578         }
1579
1580       if (p == this->segment_list_.end())
1581         {
1582           Output_segment* oseg = this->make_output_segment(elfcpp::PT_NOTE,
1583                                                            seg_flags);
1584           oseg->add_output_section_to_nonload(os, seg_flags);
1585         }
1586     }
1587
1588   // If we see a loadable SHF_TLS section, we create a PT_TLS
1589   // segment.  There can only be one such segment.
1590   if ((flags & elfcpp::SHF_TLS) != 0)
1591     {
1592       if (this->tls_segment_ == NULL)
1593         this->make_output_segment(elfcpp::PT_TLS, seg_flags);
1594       this->tls_segment_->add_output_section_to_nonload(os, seg_flags);
1595     }
1596
1597   // If -z relro is in effect, and we see a relro section, we create a
1598   // PT_GNU_RELRO segment.  There can only be one such segment.
1599   if (os->is_relro() && parameters->options().relro())
1600     {
1601       gold_assert(seg_flags == (elfcpp::PF_R | elfcpp::PF_W));
1602       if (this->relro_segment_ == NULL)
1603         this->make_output_segment(elfcpp::PT_GNU_RELRO, seg_flags);
1604       this->relro_segment_->add_output_section_to_nonload(os, seg_flags);
1605     }
1606
1607   // If we see a section named .interp, put it into a PT_INTERP
1608   // segment.  This seems broken to me, but this is what GNU ld does,
1609   // and glibc expects it.
1610   if (strcmp(os->name(), ".interp") == 0
1611       && !this->script_options_->saw_phdrs_clause())
1612     {
1613       if (this->interp_segment_ == NULL)
1614         this->make_output_segment(elfcpp::PT_INTERP, seg_flags);
1615       else
1616         gold_warning(_("multiple '.interp' sections in input files "
1617                        "may cause confusing PT_INTERP segment"));
1618       this->interp_segment_->add_output_section_to_nonload(os, seg_flags);
1619     }
1620 }
1621
1622 // Make an output section for a script.
1623
1624 Output_section*
1625 Layout::make_output_section_for_script(
1626     const char* name,
1627     Script_sections::Section_type section_type)
1628 {
1629   name = this->namepool_.add(name, false, NULL);
1630   elfcpp::Elf_Xword sh_flags = elfcpp::SHF_ALLOC;
1631   if (section_type == Script_sections::ST_NOLOAD)
1632     sh_flags = 0;
1633   Output_section* os = this->make_output_section(name, elfcpp::SHT_PROGBITS,
1634                                                  sh_flags, ORDER_INVALID,
1635                                                  false);
1636   os->set_found_in_sections_clause();
1637   if (section_type == Script_sections::ST_NOLOAD)
1638     os->set_is_noload();
1639   return os;
1640 }
1641
1642 // Return the number of segments we expect to see.
1643
1644 size_t
1645 Layout::expected_segment_count() const
1646 {
1647   size_t ret = this->segment_list_.size();
1648
1649   // If we didn't see a SECTIONS clause in a linker script, we should
1650   // already have the complete list of segments.  Otherwise we ask the
1651   // SECTIONS clause how many segments it expects, and add in the ones
1652   // we already have (PT_GNU_STACK, PT_GNU_EH_FRAME, etc.)
1653
1654   if (!this->script_options_->saw_sections_clause())
1655     return ret;
1656   else
1657     {
1658       const Script_sections* ss = this->script_options_->script_sections();
1659       return ret + ss->expected_segment_count(this);
1660     }
1661 }
1662
1663 // Handle the .note.GNU-stack section at layout time.  SEEN_GNU_STACK
1664 // is whether we saw a .note.GNU-stack section in the object file.
1665 // GNU_STACK_FLAGS is the section flags.  The flags give the
1666 // protection required for stack memory.  We record this in an
1667 // executable as a PT_GNU_STACK segment.  If an object file does not
1668 // have a .note.GNU-stack segment, we must assume that it is an old
1669 // object.  On some targets that will force an executable stack.
1670
1671 void
1672 Layout::layout_gnu_stack(bool seen_gnu_stack, uint64_t gnu_stack_flags,
1673                          const Object* obj)
1674 {
1675   if (!seen_gnu_stack)
1676     {
1677       this->input_without_gnu_stack_note_ = true;
1678       if (parameters->options().warn_execstack()
1679           && parameters->target().is_default_stack_executable())
1680         gold_warning(_("%s: missing .note.GNU-stack section"
1681                        " implies executable stack"),
1682                      obj->name().c_str());
1683     }
1684   else
1685     {
1686       this->input_with_gnu_stack_note_ = true;
1687       if ((gnu_stack_flags & elfcpp::SHF_EXECINSTR) != 0)
1688         {
1689           this->input_requires_executable_stack_ = true;
1690           if (parameters->options().warn_execstack()
1691               || parameters->options().is_stack_executable())
1692             gold_warning(_("%s: requires executable stack"),
1693                          obj->name().c_str());
1694         }
1695     }
1696 }
1697
1698 // Create automatic note sections.
1699
1700 void
1701 Layout::create_notes()
1702 {
1703   this->create_gold_note();
1704   this->create_executable_stack_info();
1705   this->create_build_id();
1706 }
1707
1708 // Create the dynamic sections which are needed before we read the
1709 // relocs.
1710
1711 void
1712 Layout::create_initial_dynamic_sections(Symbol_table* symtab)
1713 {
1714   if (parameters->doing_static_link())
1715     return;
1716
1717   this->dynamic_section_ = this->choose_output_section(NULL, ".dynamic",
1718                                                        elfcpp::SHT_DYNAMIC,
1719                                                        (elfcpp::SHF_ALLOC
1720                                                         | elfcpp::SHF_WRITE),
1721                                                        false, ORDER_RELRO,
1722                                                        true);
1723
1724   this->dynamic_symbol_ =
1725     symtab->define_in_output_data("_DYNAMIC", NULL, Symbol_table::PREDEFINED,
1726                                   this->dynamic_section_, 0, 0,
1727                                   elfcpp::STT_OBJECT, elfcpp::STB_LOCAL,
1728                                   elfcpp::STV_HIDDEN, 0, false, false);
1729
1730   this->dynamic_data_ =  new Output_data_dynamic(&this->dynpool_);
1731
1732   this->dynamic_section_->add_output_section_data(this->dynamic_data_);
1733 }
1734
1735 // For each output section whose name can be represented as C symbol,
1736 // define __start and __stop symbols for the section.  This is a GNU
1737 // extension.
1738
1739 void
1740 Layout::define_section_symbols(Symbol_table* symtab)
1741 {
1742   for (Section_list::const_iterator p = this->section_list_.begin();
1743        p != this->section_list_.end();
1744        ++p)
1745     {
1746       const char* const name = (*p)->name();
1747       if (is_cident(name))
1748         {
1749           const std::string name_string(name);
1750           const std::string start_name(cident_section_start_prefix
1751                                        + name_string);
1752           const std::string stop_name(cident_section_stop_prefix
1753                                       + name_string);
1754
1755           symtab->define_in_output_data(start_name.c_str(),
1756                                         NULL, // version
1757                                         Symbol_table::PREDEFINED,
1758                                         *p,
1759                                         0, // value
1760                                         0, // symsize
1761                                         elfcpp::STT_NOTYPE,
1762                                         elfcpp::STB_GLOBAL,
1763                                         elfcpp::STV_DEFAULT,
1764                                         0, // nonvis
1765                                         false, // offset_is_from_end
1766                                         true); // only_if_ref
1767
1768           symtab->define_in_output_data(stop_name.c_str(),
1769                                         NULL, // version
1770                                         Symbol_table::PREDEFINED,
1771                                         *p,
1772                                         0, // value
1773                                         0, // symsize
1774                                         elfcpp::STT_NOTYPE,
1775                                         elfcpp::STB_GLOBAL,
1776                                         elfcpp::STV_DEFAULT,
1777                                         0, // nonvis
1778                                         true, // offset_is_from_end
1779                                         true); // only_if_ref
1780         }
1781     }
1782 }
1783
1784 // Define symbols for group signatures.
1785
1786 void
1787 Layout::define_group_signatures(Symbol_table* symtab)
1788 {
1789   for (Group_signatures::iterator p = this->group_signatures_.begin();
1790        p != this->group_signatures_.end();
1791        ++p)
1792     {
1793       Symbol* sym = symtab->lookup(p->signature, NULL);
1794       if (sym != NULL)
1795         p->section->set_info_symndx(sym);
1796       else
1797         {
1798           // Force the name of the group section to the group
1799           // signature, and use the group's section symbol as the
1800           // signature symbol.
1801           if (strcmp(p->section->name(), p->signature) != 0)
1802             {
1803               const char* name = this->namepool_.add(p->signature,
1804                                                      true, NULL);
1805               p->section->set_name(name);
1806             }
1807           p->section->set_needs_symtab_index();
1808           p->section->set_info_section_symndx(p->section);
1809         }
1810     }
1811
1812   this->group_signatures_.clear();
1813 }
1814
1815 // Find the first read-only PT_LOAD segment, creating one if
1816 // necessary.
1817
1818 Output_segment*
1819 Layout::find_first_load_seg()
1820 {
1821   Output_segment* best = NULL;
1822   for (Segment_list::const_iterator p = this->segment_list_.begin();
1823        p != this->segment_list_.end();
1824        ++p)
1825     {
1826       if ((*p)->type() == elfcpp::PT_LOAD
1827           && ((*p)->flags() & elfcpp::PF_R) != 0
1828           && (parameters->options().omagic()
1829               || ((*p)->flags() & elfcpp::PF_W) == 0))
1830         {
1831           if (best == NULL || this->segment_precedes(*p, best))
1832             best = *p;
1833         }
1834     }
1835   if (best != NULL)
1836     return best;
1837
1838   gold_assert(!this->script_options_->saw_phdrs_clause());
1839
1840   Output_segment* load_seg = this->make_output_segment(elfcpp::PT_LOAD,
1841                                                        elfcpp::PF_R);
1842   return load_seg;
1843 }
1844
1845 // Save states of all current output segments.  Store saved states
1846 // in SEGMENT_STATES.
1847
1848 void
1849 Layout::save_segments(Segment_states* segment_states)
1850 {
1851   for (Segment_list::const_iterator p = this->segment_list_.begin();
1852        p != this->segment_list_.end();
1853        ++p)
1854     {
1855       Output_segment* segment = *p;
1856       // Shallow copy.
1857       Output_segment* copy = new Output_segment(*segment);
1858       (*segment_states)[segment] = copy;
1859     }
1860 }
1861
1862 // Restore states of output segments and delete any segment not found in
1863 // SEGMENT_STATES.
1864
1865 void
1866 Layout::restore_segments(const Segment_states* segment_states)
1867 {
1868   // Go through the segment list and remove any segment added in the
1869   // relaxation loop.
1870   this->tls_segment_ = NULL;
1871   this->relro_segment_ = NULL;
1872   Segment_list::iterator list_iter = this->segment_list_.begin();
1873   while (list_iter != this->segment_list_.end())
1874     {
1875       Output_segment* segment = *list_iter;
1876       Segment_states::const_iterator states_iter =
1877           segment_states->find(segment);
1878       if (states_iter != segment_states->end())
1879         {
1880           const Output_segment* copy = states_iter->second;
1881           // Shallow copy to restore states.
1882           *segment = *copy;
1883
1884           // Also fix up TLS and RELRO segment pointers as appropriate.
1885           if (segment->type() == elfcpp::PT_TLS)
1886             this->tls_segment_ = segment;
1887           else if (segment->type() == elfcpp::PT_GNU_RELRO)
1888             this->relro_segment_ = segment;
1889
1890           ++list_iter;
1891         } 
1892       else
1893         {
1894           list_iter = this->segment_list_.erase(list_iter); 
1895           // This is a segment created during section layout.  It should be
1896           // safe to remove it since we should have removed all pointers to it.
1897           delete segment;
1898         }
1899     }
1900 }
1901
1902 // Clean up after relaxation so that sections can be laid out again.
1903
1904 void
1905 Layout::clean_up_after_relaxation()
1906 {
1907   // Restore the segments to point state just prior to the relaxation loop.
1908   Script_sections* script_section = this->script_options_->script_sections();
1909   script_section->release_segments();
1910   this->restore_segments(this->segment_states_);
1911
1912   // Reset section addresses and file offsets
1913   for (Section_list::iterator p = this->section_list_.begin();
1914        p != this->section_list_.end();
1915        ++p)
1916     {
1917       (*p)->restore_states();
1918
1919       // If an input section changes size because of relaxation,
1920       // we need to adjust the section offsets of all input sections.
1921       // after such a section.
1922       if ((*p)->section_offsets_need_adjustment())
1923         (*p)->adjust_section_offsets();
1924
1925       (*p)->reset_address_and_file_offset();
1926     }
1927   
1928   // Reset special output object address and file offsets.
1929   for (Data_list::iterator p = this->special_output_list_.begin();
1930        p != this->special_output_list_.end();
1931        ++p)
1932     (*p)->reset_address_and_file_offset();
1933
1934   // A linker script may have created some output section data objects.
1935   // They are useless now.
1936   for (Output_section_data_list::const_iterator p =
1937          this->script_output_section_data_list_.begin();
1938        p != this->script_output_section_data_list_.end();
1939        ++p)
1940     delete *p;
1941   this->script_output_section_data_list_.clear(); 
1942 }
1943
1944 // Prepare for relaxation.
1945
1946 void
1947 Layout::prepare_for_relaxation()
1948 {
1949   // Create an relaxation debug check if in debugging mode.
1950   if (is_debugging_enabled(DEBUG_RELAXATION))
1951     this->relaxation_debug_check_ = new Relaxation_debug_check();
1952
1953   // Save segment states.
1954   this->segment_states_ = new Segment_states();
1955   this->save_segments(this->segment_states_);
1956
1957   for(Section_list::const_iterator p = this->section_list_.begin();
1958       p != this->section_list_.end();
1959       ++p)
1960     (*p)->save_states();
1961
1962   if (is_debugging_enabled(DEBUG_RELAXATION))
1963     this->relaxation_debug_check_->check_output_data_for_reset_values(
1964         this->section_list_, this->special_output_list_);
1965
1966   // Also enable recording of output section data from scripts.
1967   this->record_output_section_data_from_script_ = true;
1968 }
1969
1970 // Relaxation loop body:  If target has no relaxation, this runs only once
1971 // Otherwise, the target relaxation hook is called at the end of
1972 // each iteration.  If the hook returns true, it means re-layout of
1973 // section is required.  
1974 //
1975 // The number of segments created by a linking script without a PHDRS
1976 // clause may be affected by section sizes and alignments.  There is
1977 // a remote chance that relaxation causes different number of PT_LOAD
1978 // segments are created and sections are attached to different segments.
1979 // Therefore, we always throw away all segments created during section
1980 // layout.  In order to be able to restart the section layout, we keep
1981 // a copy of the segment list right before the relaxation loop and use
1982 // that to restore the segments.
1983 // 
1984 // PASS is the current relaxation pass number. 
1985 // SYMTAB is a symbol table.
1986 // PLOAD_SEG is the address of a pointer for the load segment.
1987 // PHDR_SEG is a pointer to the PHDR segment.
1988 // SEGMENT_HEADERS points to the output segment header.
1989 // FILE_HEADER points to the output file header.
1990 // PSHNDX is the address to store the output section index.
1991
1992 off_t inline
1993 Layout::relaxation_loop_body(
1994     int pass,
1995     Target* target,
1996     Symbol_table* symtab,
1997     Output_segment** pload_seg,
1998     Output_segment* phdr_seg,
1999     Output_segment_headers* segment_headers,
2000     Output_file_header* file_header,
2001     unsigned int* pshndx)
2002 {
2003   // If this is not the first iteration, we need to clean up after
2004   // relaxation so that we can lay out the sections again.
2005   if (pass != 0)
2006     this->clean_up_after_relaxation();
2007
2008   // If there is a SECTIONS clause, put all the input sections into
2009   // the required order.
2010   Output_segment* load_seg;
2011   if (this->script_options_->saw_sections_clause())
2012     load_seg = this->set_section_addresses_from_script(symtab);
2013   else if (parameters->options().relocatable())
2014     load_seg = NULL;
2015   else
2016     load_seg = this->find_first_load_seg();
2017
2018   if (parameters->options().oformat_enum()
2019       != General_options::OBJECT_FORMAT_ELF)
2020     load_seg = NULL;
2021
2022   // If the user set the address of the text segment, that may not be
2023   // compatible with putting the segment headers and file headers into
2024   // that segment.
2025   if (parameters->options().user_set_Ttext())
2026     load_seg = NULL;
2027
2028   gold_assert(phdr_seg == NULL
2029               || load_seg != NULL
2030               || this->script_options_->saw_sections_clause());
2031
2032   // If the address of the load segment we found has been set by
2033   // --section-start rather than by a script, then adjust the VMA and
2034   // LMA downward if possible to include the file and section headers.
2035   uint64_t header_gap = 0;
2036   if (load_seg != NULL
2037       && load_seg->are_addresses_set()
2038       && !this->script_options_->saw_sections_clause()
2039       && !parameters->options().relocatable())
2040     {
2041       file_header->finalize_data_size();
2042       segment_headers->finalize_data_size();
2043       size_t sizeof_headers = (file_header->data_size()
2044                                + segment_headers->data_size());
2045       const uint64_t abi_pagesize = target->abi_pagesize();
2046       uint64_t hdr_paddr = load_seg->paddr() - sizeof_headers;
2047       hdr_paddr &= ~(abi_pagesize - 1);
2048       uint64_t subtract = load_seg->paddr() - hdr_paddr;
2049       if (load_seg->paddr() < subtract || load_seg->vaddr() < subtract)
2050         load_seg = NULL;
2051       else
2052         {
2053           load_seg->set_addresses(load_seg->vaddr() - subtract,
2054                                   load_seg->paddr() - subtract);
2055           header_gap = subtract - sizeof_headers;
2056         }
2057     }
2058
2059   // Lay out the segment headers.
2060   if (!parameters->options().relocatable())
2061     {
2062       gold_assert(segment_headers != NULL);
2063       if (header_gap != 0 && load_seg != NULL)
2064         {
2065           Output_data_zero_fill* z = new Output_data_zero_fill(header_gap, 1);
2066           load_seg->add_initial_output_data(z);
2067         }
2068       if (load_seg != NULL)
2069         load_seg->add_initial_output_data(segment_headers);
2070       if (phdr_seg != NULL)
2071         phdr_seg->add_initial_output_data(segment_headers);
2072     }
2073
2074   // Lay out the file header.
2075   if (load_seg != NULL)
2076     load_seg->add_initial_output_data(file_header);
2077
2078   if (this->script_options_->saw_phdrs_clause()
2079       && !parameters->options().relocatable())
2080     {
2081       // Support use of FILEHDRS and PHDRS attachments in a PHDRS
2082       // clause in a linker script.
2083       Script_sections* ss = this->script_options_->script_sections();
2084       ss->put_headers_in_phdrs(file_header, segment_headers);
2085     }
2086
2087   // We set the output section indexes in set_segment_offsets and
2088   // set_section_indexes.
2089   *pshndx = 1;
2090
2091   // Set the file offsets of all the segments, and all the sections
2092   // they contain.
2093   off_t off;
2094   if (!parameters->options().relocatable())
2095     off = this->set_segment_offsets(target, load_seg, pshndx);
2096   else
2097     off = this->set_relocatable_section_offsets(file_header, pshndx);
2098
2099    // Verify that the dummy relaxation does not change anything.
2100   if (is_debugging_enabled(DEBUG_RELAXATION))
2101     {
2102       if (pass == 0)
2103         this->relaxation_debug_check_->read_sections(this->section_list_);
2104       else
2105         this->relaxation_debug_check_->verify_sections(this->section_list_);
2106     }
2107
2108   *pload_seg = load_seg;
2109   return off;
2110 }
2111
2112 // Search the list of patterns and find the postion of the given section
2113 // name in the output section.  If the section name matches a glob
2114 // pattern and a non-glob name, then the non-glob position takes
2115 // precedence.  Return 0 if no match is found.
2116
2117 unsigned int
2118 Layout::find_section_order_index(const std::string& section_name)
2119 {
2120   Unordered_map<std::string, unsigned int>::iterator map_it;
2121   map_it = this->input_section_position_.find(section_name);
2122   if (map_it != this->input_section_position_.end())
2123     return map_it->second;
2124
2125   // Absolute match failed.  Linear search the glob patterns.
2126   std::vector<std::string>::iterator it;
2127   for (it = this->input_section_glob_.begin();
2128        it != this->input_section_glob_.end();
2129        ++it)
2130     {
2131        if (fnmatch((*it).c_str(), section_name.c_str(), FNM_NOESCAPE) == 0)
2132          {
2133            map_it = this->input_section_position_.find(*it);
2134            gold_assert(map_it != this->input_section_position_.end());
2135            return map_it->second;
2136          }
2137     }
2138   return 0;
2139 }
2140
2141 // Read the sequence of input sections from the file specified with
2142 // --section-ordering-file.
2143
2144 void
2145 Layout::read_layout_from_file()
2146 {
2147   const char* filename = parameters->options().section_ordering_file();
2148   std::ifstream in;
2149   std::string line;
2150
2151   in.open(filename);
2152   if (!in)
2153     gold_fatal(_("unable to open --section-ordering-file file %s: %s"),
2154                filename, strerror(errno));
2155
2156   std::getline(in, line);   // this chops off the trailing \n, if any
2157   unsigned int position = 1;
2158
2159   while (in)
2160     {
2161       if (!line.empty() && line[line.length() - 1] == '\r')   // Windows
2162         line.resize(line.length() - 1);
2163       // Ignore comments, beginning with '#'
2164       if (line[0] == '#')
2165         {
2166           std::getline(in, line);
2167           continue;
2168         }
2169       this->input_section_position_[line] = position;
2170       // Store all glob patterns in a vector.
2171       if (is_wildcard_string(line.c_str()))
2172         this->input_section_glob_.push_back(line);
2173       position++;
2174       std::getline(in, line);
2175     }
2176 }
2177
2178 // Finalize the layout.  When this is called, we have created all the
2179 // output sections and all the output segments which are based on
2180 // input sections.  We have several things to do, and we have to do
2181 // them in the right order, so that we get the right results correctly
2182 // and efficiently.
2183
2184 // 1) Finalize the list of output segments and create the segment
2185 // table header.
2186
2187 // 2) Finalize the dynamic symbol table and associated sections.
2188
2189 // 3) Determine the final file offset of all the output segments.
2190
2191 // 4) Determine the final file offset of all the SHF_ALLOC output
2192 // sections.
2193
2194 // 5) Create the symbol table sections and the section name table
2195 // section.
2196
2197 // 6) Finalize the symbol table: set symbol values to their final
2198 // value and make a final determination of which symbols are going
2199 // into the output symbol table.
2200
2201 // 7) Create the section table header.
2202
2203 // 8) Determine the final file offset of all the output sections which
2204 // are not SHF_ALLOC, including the section table header.
2205
2206 // 9) Finalize the ELF file header.
2207
2208 // This function returns the size of the output file.
2209
2210 off_t
2211 Layout::finalize(const Input_objects* input_objects, Symbol_table* symtab,
2212                  Target* target, const Task* task)
2213 {
2214   target->finalize_sections(this, input_objects, symtab);
2215
2216   this->count_local_symbols(task, input_objects);
2217
2218   this->link_stabs_sections();
2219
2220   Output_segment* phdr_seg = NULL;
2221   if (!parameters->options().relocatable() && !parameters->doing_static_link())
2222     {
2223       // There was a dynamic object in the link.  We need to create
2224       // some information for the dynamic linker.
2225
2226       // Create the PT_PHDR segment which will hold the program
2227       // headers.
2228       if (!this->script_options_->saw_phdrs_clause())
2229         phdr_seg = this->make_output_segment(elfcpp::PT_PHDR, elfcpp::PF_R);
2230
2231       // Create the dynamic symbol table, including the hash table.
2232       Output_section* dynstr;
2233       std::vector<Symbol*> dynamic_symbols;
2234       unsigned int local_dynamic_count;
2235       Versions versions(*this->script_options()->version_script_info(),
2236                         &this->dynpool_);
2237       this->create_dynamic_symtab(input_objects, symtab, &dynstr,
2238                                   &local_dynamic_count, &dynamic_symbols,
2239                                   &versions);
2240
2241       // Create the .interp section to hold the name of the
2242       // interpreter, and put it in a PT_INTERP segment.  Don't do it
2243       // if we saw a .interp section in an input file.
2244       if ((!parameters->options().shared()
2245            || parameters->options().dynamic_linker() != NULL)
2246           && this->interp_segment_ == NULL)
2247         this->create_interp(target);
2248
2249       // Finish the .dynamic section to hold the dynamic data, and put
2250       // it in a PT_DYNAMIC segment.
2251       this->finish_dynamic_section(input_objects, symtab);
2252
2253       // We should have added everything we need to the dynamic string
2254       // table.
2255       this->dynpool_.set_string_offsets();
2256
2257       // Create the version sections.  We can't do this until the
2258       // dynamic string table is complete.
2259       this->create_version_sections(&versions, symtab, local_dynamic_count,
2260                                     dynamic_symbols, dynstr);
2261
2262       // Set the size of the _DYNAMIC symbol.  We can't do this until
2263       // after we call create_version_sections.
2264       this->set_dynamic_symbol_size(symtab);
2265     }
2266   
2267   // Create segment headers.
2268   Output_segment_headers* segment_headers =
2269     (parameters->options().relocatable()
2270      ? NULL
2271      : new Output_segment_headers(this->segment_list_));
2272
2273   // Lay out the file header.
2274   Output_file_header* file_header = new Output_file_header(target, symtab,
2275                                                            segment_headers);
2276
2277   this->special_output_list_.push_back(file_header);
2278   if (segment_headers != NULL)
2279     this->special_output_list_.push_back(segment_headers);
2280
2281   // Find approriate places for orphan output sections if we are using
2282   // a linker script.
2283   if (this->script_options_->saw_sections_clause())
2284     this->place_orphan_sections_in_script();
2285   
2286   Output_segment* load_seg;
2287   off_t off;
2288   unsigned int shndx;
2289   int pass = 0;
2290
2291   // Take a snapshot of the section layout as needed.
2292   if (target->may_relax())
2293     this->prepare_for_relaxation();
2294   
2295   // Run the relaxation loop to lay out sections.
2296   do
2297     {
2298       off = this->relaxation_loop_body(pass, target, symtab, &load_seg,
2299                                        phdr_seg, segment_headers, file_header,
2300                                        &shndx);
2301       pass++;
2302     }
2303   while (target->may_relax()
2304          && target->relax(pass, input_objects, symtab, this, task));
2305
2306   // Set the file offsets of all the non-data sections we've seen so
2307   // far which don't have to wait for the input sections.  We need
2308   // this in order to finalize local symbols in non-allocated
2309   // sections.
2310   off = this->set_section_offsets(off, BEFORE_INPUT_SECTIONS_PASS);
2311
2312   // Set the section indexes of all unallocated sections seen so far,
2313   // in case any of them are somehow referenced by a symbol.
2314   shndx = this->set_section_indexes(shndx);
2315
2316   // Create the symbol table sections.
2317   this->create_symtab_sections(input_objects, symtab, shndx, &off);
2318   if (!parameters->doing_static_link())
2319     this->assign_local_dynsym_offsets(input_objects);
2320
2321   // Process any symbol assignments from a linker script.  This must
2322   // be called after the symbol table has been finalized.
2323   this->script_options_->finalize_symbols(symtab, this);
2324
2325   // Create the incremental inputs sections.
2326   if (this->incremental_inputs_)
2327     {
2328       this->incremental_inputs_->finalize();
2329       this->create_incremental_info_sections(symtab);
2330     }
2331
2332   // Create the .shstrtab section.
2333   Output_section* shstrtab_section = this->create_shstrtab();
2334
2335   // Set the file offsets of the rest of the non-data sections which
2336   // don't have to wait for the input sections.
2337   off = this->set_section_offsets(off, BEFORE_INPUT_SECTIONS_PASS);
2338
2339   // Now that all sections have been created, set the section indexes
2340   // for any sections which haven't been done yet.
2341   shndx = this->set_section_indexes(shndx);
2342
2343   // Create the section table header.
2344   this->create_shdrs(shstrtab_section, &off);
2345
2346   // If there are no sections which require postprocessing, we can
2347   // handle the section names now, and avoid a resize later.
2348   if (!this->any_postprocessing_sections_)
2349     {
2350       off = this->set_section_offsets(off,
2351                                       POSTPROCESSING_SECTIONS_PASS);
2352       off =
2353           this->set_section_offsets(off,
2354                                     STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS);
2355     }
2356
2357   file_header->set_section_info(this->section_headers_, shstrtab_section);
2358
2359   // Now we know exactly where everything goes in the output file
2360   // (except for non-allocated sections which require postprocessing).
2361   Output_data::layout_complete();
2362
2363   this->output_file_size_ = off;
2364
2365   return off;
2366 }
2367
2368 // Create a note header following the format defined in the ELF ABI.
2369 // NAME is the name, NOTE_TYPE is the type, SECTION_NAME is the name
2370 // of the section to create, DESCSZ is the size of the descriptor.
2371 // ALLOCATE is true if the section should be allocated in memory.
2372 // This returns the new note section.  It sets *TRAILING_PADDING to
2373 // the number of trailing zero bytes required.
2374
2375 Output_section*
2376 Layout::create_note(const char* name, int note_type,
2377                     const char* section_name, size_t descsz,
2378                     bool allocate, size_t* trailing_padding)
2379 {
2380   // Authorities all agree that the values in a .note field should
2381   // be aligned on 4-byte boundaries for 32-bit binaries.  However,
2382   // they differ on what the alignment is for 64-bit binaries.
2383   // The GABI says unambiguously they take 8-byte alignment:
2384   //    http://sco.com/developers/gabi/latest/ch5.pheader.html#note_section
2385   // Other documentation says alignment should always be 4 bytes:
2386   //    http://www.netbsd.org/docs/kernel/elf-notes.html#note-format
2387   // GNU ld and GNU readelf both support the latter (at least as of
2388   // version 2.16.91), and glibc always generates the latter for
2389   // .note.ABI-tag (as of version 1.6), so that's the one we go with
2390   // here.
2391 #ifdef GABI_FORMAT_FOR_DOTNOTE_SECTION   // This is not defined by default.
2392   const int size = parameters->target().get_size();
2393 #else
2394   const int size = 32;
2395 #endif
2396
2397   // The contents of the .note section.
2398   size_t namesz = strlen(name) + 1;
2399   size_t aligned_namesz = align_address(namesz, size / 8);
2400   size_t aligned_descsz = align_address(descsz, size / 8);
2401
2402   size_t notehdrsz = 3 * (size / 8) + aligned_namesz;
2403
2404   unsigned char* buffer = new unsigned char[notehdrsz];
2405   memset(buffer, 0, notehdrsz);
2406
2407   bool is_big_endian = parameters->target().is_big_endian();
2408
2409   if (size == 32)
2410     {
2411       if (!is_big_endian)
2412         {
2413           elfcpp::Swap<32, false>::writeval(buffer, namesz);
2414           elfcpp::Swap<32, false>::writeval(buffer + 4, descsz);
2415           elfcpp::Swap<32, false>::writeval(buffer + 8, note_type);
2416         }
2417       else
2418         {
2419           elfcpp::Swap<32, true>::writeval(buffer, namesz);
2420           elfcpp::Swap<32, true>::writeval(buffer + 4, descsz);
2421           elfcpp::Swap<32, true>::writeval(buffer + 8, note_type);
2422         }
2423     }
2424   else if (size == 64)
2425     {
2426       if (!is_big_endian)
2427         {
2428           elfcpp::Swap<64, false>::writeval(buffer, namesz);
2429           elfcpp::Swap<64, false>::writeval(buffer + 8, descsz);
2430           elfcpp::Swap<64, false>::writeval(buffer + 16, note_type);
2431         }
2432       else
2433         {
2434           elfcpp::Swap<64, true>::writeval(buffer, namesz);
2435           elfcpp::Swap<64, true>::writeval(buffer + 8, descsz);
2436           elfcpp::Swap<64, true>::writeval(buffer + 16, note_type);
2437         }
2438     }
2439   else
2440     gold_unreachable();
2441
2442   memcpy(buffer + 3 * (size / 8), name, namesz);
2443
2444   elfcpp::Elf_Xword flags = 0;
2445   Output_section_order order = ORDER_INVALID;
2446   if (allocate)
2447     {
2448       flags = elfcpp::SHF_ALLOC;
2449       order = ORDER_RO_NOTE;
2450     }
2451   Output_section* os = this->choose_output_section(NULL, section_name,
2452                                                    elfcpp::SHT_NOTE,
2453                                                    flags, false, order, false);
2454   if (os == NULL)
2455     return NULL;
2456
2457   Output_section_data* posd = new Output_data_const_buffer(buffer, notehdrsz,
2458                                                            size / 8,
2459                                                            "** note header");
2460   os->add_output_section_data(posd);
2461
2462   *trailing_padding = aligned_descsz - descsz;
2463
2464   return os;
2465 }
2466
2467 // For an executable or shared library, create a note to record the
2468 // version of gold used to create the binary.
2469
2470 void
2471 Layout::create_gold_note()
2472 {
2473   if (parameters->options().relocatable()
2474       || parameters->incremental_update())
2475     return;
2476
2477   std::string desc = std::string("gold ") + gold::get_version_string();
2478
2479   size_t trailing_padding;
2480   Output_section* os = this->create_note("GNU", elfcpp::NT_GNU_GOLD_VERSION,
2481                                          ".note.gnu.gold-version", desc.size(),
2482                                          false, &trailing_padding);
2483   if (os == NULL)
2484     return;
2485
2486   Output_section_data* posd = new Output_data_const(desc, 4);
2487   os->add_output_section_data(posd);
2488
2489   if (trailing_padding > 0)
2490     {
2491       posd = new Output_data_zero_fill(trailing_padding, 0);
2492       os->add_output_section_data(posd);
2493     }
2494 }
2495
2496 // Record whether the stack should be executable.  This can be set
2497 // from the command line using the -z execstack or -z noexecstack
2498 // options.  Otherwise, if any input file has a .note.GNU-stack
2499 // section with the SHF_EXECINSTR flag set, the stack should be
2500 // executable.  Otherwise, if at least one input file a
2501 // .note.GNU-stack section, and some input file has no .note.GNU-stack
2502 // section, we use the target default for whether the stack should be
2503 // executable.  Otherwise, we don't generate a stack note.  When
2504 // generating a object file, we create a .note.GNU-stack section with
2505 // the appropriate marking.  When generating an executable or shared
2506 // library, we create a PT_GNU_STACK segment.
2507
2508 void
2509 Layout::create_executable_stack_info()
2510 {
2511   bool is_stack_executable;
2512   if (parameters->options().is_execstack_set())
2513     is_stack_executable = parameters->options().is_stack_executable();
2514   else if (!this->input_with_gnu_stack_note_)
2515     return;
2516   else
2517     {
2518       if (this->input_requires_executable_stack_)
2519         is_stack_executable = true;
2520       else if (this->input_without_gnu_stack_note_)
2521         is_stack_executable =
2522           parameters->target().is_default_stack_executable();
2523       else
2524         is_stack_executable = false;
2525     }
2526
2527   if (parameters->options().relocatable())
2528     {
2529       const char* name = this->namepool_.add(".note.GNU-stack", false, NULL);
2530       elfcpp::Elf_Xword flags = 0;
2531       if (is_stack_executable)
2532         flags |= elfcpp::SHF_EXECINSTR;
2533       this->make_output_section(name, elfcpp::SHT_PROGBITS, flags,
2534                                 ORDER_INVALID, false);
2535     }
2536   else
2537     {
2538       if (this->script_options_->saw_phdrs_clause())
2539         return;
2540       int flags = elfcpp::PF_R | elfcpp::PF_W;
2541       if (is_stack_executable)
2542         flags |= elfcpp::PF_X;
2543       this->make_output_segment(elfcpp::PT_GNU_STACK, flags);
2544     }
2545 }
2546
2547 // If --build-id was used, set up the build ID note.
2548
2549 void
2550 Layout::create_build_id()
2551 {
2552   if (!parameters->options().user_set_build_id())
2553     return;
2554
2555   const char* style = parameters->options().build_id();
2556   if (strcmp(style, "none") == 0)
2557     return;
2558
2559   // Set DESCSZ to the size of the note descriptor.  When possible,
2560   // set DESC to the note descriptor contents.
2561   size_t descsz;
2562   std::string desc;
2563   if (strcmp(style, "md5") == 0)
2564     descsz = 128 / 8;
2565   else if (strcmp(style, "sha1") == 0)
2566     descsz = 160 / 8;
2567   else if (strcmp(style, "uuid") == 0)
2568     {
2569       const size_t uuidsz = 128 / 8;
2570
2571       char buffer[uuidsz];
2572       memset(buffer, 0, uuidsz);
2573
2574       int descriptor = open_descriptor(-1, "/dev/urandom", O_RDONLY);
2575       if (descriptor < 0)
2576         gold_error(_("--build-id=uuid failed: could not open /dev/urandom: %s"),
2577                    strerror(errno));
2578       else
2579         {
2580           ssize_t got = ::read(descriptor, buffer, uuidsz);
2581           release_descriptor(descriptor, true);
2582           if (got < 0)
2583             gold_error(_("/dev/urandom: read failed: %s"), strerror(errno));
2584           else if (static_cast<size_t>(got) != uuidsz)
2585             gold_error(_("/dev/urandom: expected %zu bytes, got %zd bytes"),
2586                        uuidsz, got);
2587         }
2588
2589       desc.assign(buffer, uuidsz);
2590       descsz = uuidsz;
2591     }
2592   else if (strncmp(style, "0x", 2) == 0)
2593     {
2594       hex_init();
2595       const char* p = style + 2;
2596       while (*p != '\0')
2597         {
2598           if (hex_p(p[0]) && hex_p(p[1]))
2599             {
2600               char c = (hex_value(p[0]) << 4) | hex_value(p[1]);
2601               desc += c;
2602               p += 2;
2603             }
2604           else if (*p == '-' || *p == ':')
2605             ++p;
2606           else
2607             gold_fatal(_("--build-id argument '%s' not a valid hex number"),
2608                        style);
2609         }
2610       descsz = desc.size();
2611     }
2612   else
2613     gold_fatal(_("unrecognized --build-id argument '%s'"), style);
2614
2615   // Create the note.
2616   size_t trailing_padding;
2617   Output_section* os = this->create_note("GNU", elfcpp::NT_GNU_BUILD_ID,
2618                                          ".note.gnu.build-id", descsz, true,
2619                                          &trailing_padding);
2620   if (os == NULL)
2621     return;
2622
2623   if (!desc.empty())
2624     {
2625       // We know the value already, so we fill it in now.
2626       gold_assert(desc.size() == descsz);
2627
2628       Output_section_data* posd = new Output_data_const(desc, 4);
2629       os->add_output_section_data(posd);
2630
2631       if (trailing_padding != 0)
2632         {
2633           posd = new Output_data_zero_fill(trailing_padding, 0);
2634           os->add_output_section_data(posd);
2635         }
2636     }
2637   else
2638     {
2639       // We need to compute a checksum after we have completed the
2640       // link.
2641       gold_assert(trailing_padding == 0);
2642       this->build_id_note_ = new Output_data_zero_fill(descsz, 4);
2643       os->add_output_section_data(this->build_id_note_);
2644     }
2645 }
2646
2647 // If we have both .stabXX and .stabXXstr sections, then the sh_link
2648 // field of the former should point to the latter.  I'm not sure who
2649 // started this, but the GNU linker does it, and some tools depend
2650 // upon it.
2651
2652 void
2653 Layout::link_stabs_sections()
2654 {
2655   if (!this->have_stabstr_section_)
2656     return;
2657
2658   for (Section_list::iterator p = this->section_list_.begin();
2659        p != this->section_list_.end();
2660        ++p)
2661     {
2662       if ((*p)->type() != elfcpp::SHT_STRTAB)
2663         continue;
2664
2665       const char* name = (*p)->name();
2666       if (strncmp(name, ".stab", 5) != 0)
2667         continue;
2668
2669       size_t len = strlen(name);
2670       if (strcmp(name + len - 3, "str") != 0)
2671         continue;
2672
2673       std::string stab_name(name, len - 3);
2674       Output_section* stab_sec;
2675       stab_sec = this->find_output_section(stab_name.c_str());
2676       if (stab_sec != NULL)
2677         stab_sec->set_link_section(*p);
2678     }
2679 }
2680
2681 // Create .gnu_incremental_inputs and related sections needed
2682 // for the next run of incremental linking to check what has changed.
2683
2684 void
2685 Layout::create_incremental_info_sections(Symbol_table* symtab)
2686 {
2687   Incremental_inputs* incr = this->incremental_inputs_;
2688
2689   gold_assert(incr != NULL);
2690
2691   // Create the .gnu_incremental_inputs, _symtab, and _relocs input sections.
2692   incr->create_data_sections(symtab);
2693
2694   // Add the .gnu_incremental_inputs section.
2695   const char* incremental_inputs_name =
2696     this->namepool_.add(".gnu_incremental_inputs", false, NULL);
2697   Output_section* incremental_inputs_os =
2698     this->make_output_section(incremental_inputs_name,
2699                               elfcpp::SHT_GNU_INCREMENTAL_INPUTS, 0,
2700                               ORDER_INVALID, false);
2701   incremental_inputs_os->add_output_section_data(incr->inputs_section());
2702
2703   // Add the .gnu_incremental_symtab section.
2704   const char* incremental_symtab_name =
2705     this->namepool_.add(".gnu_incremental_symtab", false, NULL);
2706   Output_section* incremental_symtab_os =
2707     this->make_output_section(incremental_symtab_name,
2708                               elfcpp::SHT_GNU_INCREMENTAL_SYMTAB, 0,
2709                               ORDER_INVALID, false);
2710   incremental_symtab_os->add_output_section_data(incr->symtab_section());
2711   incremental_symtab_os->set_entsize(4);
2712
2713   // Add the .gnu_incremental_relocs section.
2714   const char* incremental_relocs_name =
2715     this->namepool_.add(".gnu_incremental_relocs", false, NULL);
2716   Output_section* incremental_relocs_os =
2717     this->make_output_section(incremental_relocs_name,
2718                               elfcpp::SHT_GNU_INCREMENTAL_RELOCS, 0,
2719                               ORDER_INVALID, false);
2720   incremental_relocs_os->add_output_section_data(incr->relocs_section());
2721   incremental_relocs_os->set_entsize(incr->relocs_entsize());
2722
2723   // Add the .gnu_incremental_got_plt section.
2724   const char* incremental_got_plt_name =
2725     this->namepool_.add(".gnu_incremental_got_plt", false, NULL);
2726   Output_section* incremental_got_plt_os =
2727     this->make_output_section(incremental_got_plt_name,
2728                               elfcpp::SHT_GNU_INCREMENTAL_GOT_PLT, 0,
2729                               ORDER_INVALID, false);
2730   incremental_got_plt_os->add_output_section_data(incr->got_plt_section());
2731
2732   // Add the .gnu_incremental_strtab section.
2733   const char* incremental_strtab_name =
2734     this->namepool_.add(".gnu_incremental_strtab", false, NULL);
2735   Output_section* incremental_strtab_os = this->make_output_section(incremental_strtab_name,
2736                                                         elfcpp::SHT_STRTAB, 0,
2737                                                         ORDER_INVALID, false);
2738   Output_data_strtab* strtab_data =
2739       new Output_data_strtab(incr->get_stringpool());
2740   incremental_strtab_os->add_output_section_data(strtab_data);
2741
2742   incremental_inputs_os->set_after_input_sections();
2743   incremental_symtab_os->set_after_input_sections();
2744   incremental_relocs_os->set_after_input_sections();
2745   incremental_got_plt_os->set_after_input_sections();
2746
2747   incremental_inputs_os->set_link_section(incremental_strtab_os);
2748   incremental_symtab_os->set_link_section(incremental_inputs_os);
2749   incremental_relocs_os->set_link_section(incremental_inputs_os);
2750   incremental_got_plt_os->set_link_section(incremental_inputs_os);
2751 }
2752
2753 // Return whether SEG1 should be before SEG2 in the output file.  This
2754 // is based entirely on the segment type and flags.  When this is
2755 // called the segment addresses have normally not yet been set.
2756
2757 bool
2758 Layout::segment_precedes(const Output_segment* seg1,
2759                          const Output_segment* seg2)
2760 {
2761   elfcpp::Elf_Word type1 = seg1->type();
2762   elfcpp::Elf_Word type2 = seg2->type();
2763
2764   // The single PT_PHDR segment is required to precede any loadable
2765   // segment.  We simply make it always first.
2766   if (type1 == elfcpp::PT_PHDR)
2767     {
2768       gold_assert(type2 != elfcpp::PT_PHDR);
2769       return true;
2770     }
2771   if (type2 == elfcpp::PT_PHDR)
2772     return false;
2773
2774   // The single PT_INTERP segment is required to precede any loadable
2775   // segment.  We simply make it always second.
2776   if (type1 == elfcpp::PT_INTERP)
2777     {
2778       gold_assert(type2 != elfcpp::PT_INTERP);
2779       return true;
2780     }
2781   if (type2 == elfcpp::PT_INTERP)
2782     return false;
2783
2784   // We then put PT_LOAD segments before any other segments.
2785   if (type1 == elfcpp::PT_LOAD && type2 != elfcpp::PT_LOAD)
2786     return true;
2787   if (type2 == elfcpp::PT_LOAD && type1 != elfcpp::PT_LOAD)
2788     return false;
2789
2790   // We put the PT_TLS segment last except for the PT_GNU_RELRO
2791   // segment, because that is where the dynamic linker expects to find
2792   // it (this is just for efficiency; other positions would also work
2793   // correctly).
2794   if (type1 == elfcpp::PT_TLS
2795       && type2 != elfcpp::PT_TLS
2796       && type2 != elfcpp::PT_GNU_RELRO)
2797     return false;
2798   if (type2 == elfcpp::PT_TLS
2799       && type1 != elfcpp::PT_TLS
2800       && type1 != elfcpp::PT_GNU_RELRO)
2801     return true;
2802
2803   // We put the PT_GNU_RELRO segment last, because that is where the
2804   // dynamic linker expects to find it (as with PT_TLS, this is just
2805   // for efficiency).
2806   if (type1 == elfcpp::PT_GNU_RELRO && type2 != elfcpp::PT_GNU_RELRO)
2807     return false;
2808   if (type2 == elfcpp::PT_GNU_RELRO && type1 != elfcpp::PT_GNU_RELRO)
2809     return true;
2810
2811   const elfcpp::Elf_Word flags1 = seg1->flags();
2812   const elfcpp::Elf_Word flags2 = seg2->flags();
2813
2814   // The order of non-PT_LOAD segments is unimportant.  We simply sort
2815   // by the numeric segment type and flags values.  There should not
2816   // be more than one segment with the same type and flags.
2817   if (type1 != elfcpp::PT_LOAD)
2818     {
2819       if (type1 != type2)
2820         return type1 < type2;
2821       gold_assert(flags1 != flags2);
2822       return flags1 < flags2;
2823     }
2824
2825   // If the addresses are set already, sort by load address.
2826   if (seg1->are_addresses_set())
2827     {
2828       if (!seg2->are_addresses_set())
2829         return true;
2830
2831       unsigned int section_count1 = seg1->output_section_count();
2832       unsigned int section_count2 = seg2->output_section_count();
2833       if (section_count1 == 0 && section_count2 > 0)
2834         return true;
2835       if (section_count1 > 0 && section_count2 == 0)
2836         return false;
2837
2838       uint64_t paddr1 = (seg1->are_addresses_set()
2839                          ? seg1->paddr()
2840                          : seg1->first_section_load_address());
2841       uint64_t paddr2 = (seg2->are_addresses_set()
2842                          ? seg2->paddr()
2843                          : seg2->first_section_load_address());
2844
2845       if (paddr1 != paddr2)
2846         return paddr1 < paddr2;
2847     }
2848   else if (seg2->are_addresses_set())
2849     return false;
2850
2851   // A segment which holds large data comes after a segment which does
2852   // not hold large data.
2853   if (seg1->is_large_data_segment())
2854     {
2855       if (!seg2->is_large_data_segment())
2856         return false;
2857     }
2858   else if (seg2->is_large_data_segment())
2859     return true;
2860
2861   // Otherwise, we sort PT_LOAD segments based on the flags.  Readonly
2862   // segments come before writable segments.  Then writable segments
2863   // with data come before writable segments without data.  Then
2864   // executable segments come before non-executable segments.  Then
2865   // the unlikely case of a non-readable segment comes before the
2866   // normal case of a readable segment.  If there are multiple
2867   // segments with the same type and flags, we require that the
2868   // address be set, and we sort by virtual address and then physical
2869   // address.
2870   if ((flags1 & elfcpp::PF_W) != (flags2 & elfcpp::PF_W))
2871     return (flags1 & elfcpp::PF_W) == 0;
2872   if ((flags1 & elfcpp::PF_W) != 0
2873       && seg1->has_any_data_sections() != seg2->has_any_data_sections())
2874     return seg1->has_any_data_sections();
2875   if ((flags1 & elfcpp::PF_X) != (flags2 & elfcpp::PF_X))
2876     return (flags1 & elfcpp::PF_X) != 0;
2877   if ((flags1 & elfcpp::PF_R) != (flags2 & elfcpp::PF_R))
2878     return (flags1 & elfcpp::PF_R) == 0;
2879
2880   // We shouldn't get here--we shouldn't create segments which we
2881   // can't distinguish.  Unless of course we are using a weird linker
2882   // script.
2883   gold_assert(this->script_options_->saw_phdrs_clause());
2884   return false;
2885 }
2886
2887 // Increase OFF so that it is congruent to ADDR modulo ABI_PAGESIZE.
2888
2889 static off_t
2890 align_file_offset(off_t off, uint64_t addr, uint64_t abi_pagesize)
2891 {
2892   uint64_t unsigned_off = off;
2893   uint64_t aligned_off = ((unsigned_off & ~(abi_pagesize - 1))
2894                           | (addr & (abi_pagesize - 1)));
2895   if (aligned_off < unsigned_off)
2896     aligned_off += abi_pagesize;
2897   return aligned_off;
2898 }
2899
2900 // Set the file offsets of all the segments, and all the sections they
2901 // contain.  They have all been created.  LOAD_SEG must be be laid out
2902 // first.  Return the offset of the data to follow.
2903
2904 off_t
2905 Layout::set_segment_offsets(const Target* target, Output_segment* load_seg,
2906                             unsigned int* pshndx)
2907 {
2908   // Sort them into the final order.  We use a stable sort so that we
2909   // don't randomize the order of indistinguishable segments created
2910   // by linker scripts.
2911   std::stable_sort(this->segment_list_.begin(), this->segment_list_.end(),
2912                    Layout::Compare_segments(this));
2913
2914   // Find the PT_LOAD segments, and set their addresses and offsets
2915   // and their section's addresses and offsets.
2916   uint64_t addr;
2917   if (parameters->options().user_set_Ttext())
2918     addr = parameters->options().Ttext();
2919   else if (parameters->options().output_is_position_independent())
2920     addr = 0;
2921   else
2922     addr = target->default_text_segment_address();
2923   off_t off = 0;
2924
2925   // If LOAD_SEG is NULL, then the file header and segment headers
2926   // will not be loadable.  But they still need to be at offset 0 in
2927   // the file.  Set their offsets now.
2928   if (load_seg == NULL)
2929     {
2930       for (Data_list::iterator p = this->special_output_list_.begin();
2931            p != this->special_output_list_.end();
2932            ++p)
2933         {
2934           off = align_address(off, (*p)->addralign());
2935           (*p)->set_address_and_file_offset(0, off);
2936           off += (*p)->data_size();
2937         }
2938     }
2939
2940   unsigned int increase_relro = this->increase_relro_;
2941   if (this->script_options_->saw_sections_clause())
2942     increase_relro = 0;
2943
2944   const bool check_sections = parameters->options().check_sections();
2945   Output_segment* last_load_segment = NULL;
2946
2947   for (Segment_list::iterator p = this->segment_list_.begin();
2948        p != this->segment_list_.end();
2949        ++p)
2950     {
2951       if ((*p)->type() == elfcpp::PT_LOAD)
2952         {
2953           if (load_seg != NULL && load_seg != *p)
2954             gold_unreachable();
2955           load_seg = NULL;
2956
2957           bool are_addresses_set = (*p)->are_addresses_set();
2958           if (are_addresses_set)
2959             {
2960               // When it comes to setting file offsets, we care about
2961               // the physical address.
2962               addr = (*p)->paddr();
2963             }
2964           else if (parameters->options().user_set_Tdata()
2965                    && ((*p)->flags() & elfcpp::PF_W) != 0
2966                    && (!parameters->options().user_set_Tbss()
2967                        || (*p)->has_any_data_sections()))
2968             {
2969               addr = parameters->options().Tdata();
2970               are_addresses_set = true;
2971             }
2972           else if (parameters->options().user_set_Tbss()
2973                    && ((*p)->flags() & elfcpp::PF_W) != 0
2974                    && !(*p)->has_any_data_sections())
2975             {
2976               addr = parameters->options().Tbss();
2977               are_addresses_set = true;
2978             }
2979
2980           uint64_t orig_addr = addr;
2981           uint64_t orig_off = off;
2982
2983           uint64_t aligned_addr = 0;
2984           uint64_t abi_pagesize = target->abi_pagesize();
2985           uint64_t common_pagesize = target->common_pagesize();
2986
2987           if (!parameters->options().nmagic()
2988               && !parameters->options().omagic())
2989             (*p)->set_minimum_p_align(common_pagesize);
2990
2991           if (!are_addresses_set)
2992             {
2993               // Skip the address forward one page, maintaining the same
2994               // position within the page.  This lets us store both segments
2995               // overlapping on a single page in the file, but the loader will
2996               // put them on different pages in memory. We will revisit this
2997               // decision once we know the size of the segment.
2998
2999               addr = align_address(addr, (*p)->maximum_alignment());
3000               aligned_addr = addr;
3001
3002               if ((addr & (abi_pagesize - 1)) != 0)
3003                 addr = addr + abi_pagesize;
3004
3005               off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
3006             }
3007
3008           if (!parameters->options().nmagic()
3009               && !parameters->options().omagic())
3010             off = align_file_offset(off, addr, abi_pagesize);
3011           else if (load_seg == NULL)
3012             {
3013               // This is -N or -n with a section script which prevents
3014               // us from using a load segment.  We need to ensure that
3015               // the file offset is aligned to the alignment of the
3016               // segment.  This is because the linker script
3017               // implicitly assumed a zero offset.  If we don't align
3018               // here, then the alignment of the sections in the
3019               // linker script may not match the alignment of the
3020               // sections in the set_section_addresses call below,
3021               // causing an error about dot moving backward.
3022               off = align_address(off, (*p)->maximum_alignment());
3023             }
3024
3025           unsigned int shndx_hold = *pshndx;
3026           bool has_relro = false;
3027           uint64_t new_addr = (*p)->set_section_addresses(this, false, addr,
3028                                                           &increase_relro,
3029                                                           &has_relro,
3030                                                           &off, pshndx);
3031
3032           // Now that we know the size of this segment, we may be able
3033           // to save a page in memory, at the cost of wasting some
3034           // file space, by instead aligning to the start of a new
3035           // page.  Here we use the real machine page size rather than
3036           // the ABI mandated page size.  If the segment has been
3037           // aligned so that the relro data ends at a page boundary,
3038           // we do not try to realign it.
3039
3040           if (!are_addresses_set
3041               && !has_relro
3042               && aligned_addr != addr
3043               && !parameters->incremental())
3044             {
3045               uint64_t first_off = (common_pagesize
3046                                     - (aligned_addr
3047                                        & (common_pagesize - 1)));
3048               uint64_t last_off = new_addr & (common_pagesize - 1);
3049               if (first_off > 0
3050                   && last_off > 0
3051                   && ((aligned_addr & ~ (common_pagesize - 1))
3052                       != (new_addr & ~ (common_pagesize - 1)))
3053                   && first_off + last_off <= common_pagesize)
3054                 {
3055                   *pshndx = shndx_hold;
3056                   addr = align_address(aligned_addr, common_pagesize);
3057                   addr = align_address(addr, (*p)->maximum_alignment());
3058                   off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
3059                   off = align_file_offset(off, addr, abi_pagesize);
3060
3061                   increase_relro = this->increase_relro_;
3062                   if (this->script_options_->saw_sections_clause())
3063                     increase_relro = 0;
3064                   has_relro = false;
3065
3066                   new_addr = (*p)->set_section_addresses(this, true, addr,
3067                                                          &increase_relro,
3068                                                          &has_relro,
3069                                                          &off, pshndx);
3070                 }
3071             }
3072
3073           addr = new_addr;
3074
3075           // Implement --check-sections.  We know that the segments
3076           // are sorted by LMA.
3077           if (check_sections && last_load_segment != NULL)
3078             {
3079               gold_assert(last_load_segment->paddr() <= (*p)->paddr());
3080               if (last_load_segment->paddr() + last_load_segment->memsz()
3081                   > (*p)->paddr())
3082                 {
3083                   unsigned long long lb1 = last_load_segment->paddr();
3084                   unsigned long long le1 = lb1 + last_load_segment->memsz();
3085                   unsigned long long lb2 = (*p)->paddr();
3086                   unsigned long long le2 = lb2 + (*p)->memsz();
3087                   gold_error(_("load segment overlap [0x%llx -> 0x%llx] and "
3088                                "[0x%llx -> 0x%llx]"),
3089                              lb1, le1, lb2, le2);
3090                 }
3091             }
3092           last_load_segment = *p;
3093         }
3094     }
3095
3096   // Handle the non-PT_LOAD segments, setting their offsets from their
3097   // section's offsets.
3098   for (Segment_list::iterator p = this->segment_list_.begin();
3099        p != this->segment_list_.end();
3100        ++p)
3101     {
3102       if ((*p)->type() != elfcpp::PT_LOAD)
3103         (*p)->set_offset((*p)->type() == elfcpp::PT_GNU_RELRO
3104                          ? increase_relro
3105                          : 0);
3106     }
3107
3108   // Set the TLS offsets for each section in the PT_TLS segment.
3109   if (this->tls_segment_ != NULL)
3110     this->tls_segment_->set_tls_offsets();
3111
3112   return off;
3113 }
3114
3115 // Set the offsets of all the allocated sections when doing a
3116 // relocatable link.  This does the same jobs as set_segment_offsets,
3117 // only for a relocatable link.
3118
3119 off_t
3120 Layout::set_relocatable_section_offsets(Output_data* file_header,
3121                                         unsigned int* pshndx)
3122 {
3123   off_t off = 0;
3124
3125   file_header->set_address_and_file_offset(0, 0);
3126   off += file_header->data_size();
3127
3128   for (Section_list::iterator p = this->section_list_.begin();
3129        p != this->section_list_.end();
3130        ++p)
3131     {
3132       // We skip unallocated sections here, except that group sections
3133       // have to come first.
3134       if (((*p)->flags() & elfcpp::SHF_ALLOC) == 0
3135           && (*p)->type() != elfcpp::SHT_GROUP)
3136         continue;
3137
3138       off = align_address(off, (*p)->addralign());
3139
3140       // The linker script might have set the address.
3141       if (!(*p)->is_address_valid())
3142         (*p)->set_address(0);
3143       (*p)->set_file_offset(off);
3144       (*p)->finalize_data_size();
3145       off += (*p)->data_size();
3146
3147       (*p)->set_out_shndx(*pshndx);
3148       ++*pshndx;
3149     }
3150
3151   return off;
3152 }
3153
3154 // Set the file offset of all the sections not associated with a
3155 // segment.
3156
3157 off_t
3158 Layout::set_section_offsets(off_t off, Layout::Section_offset_pass pass)
3159 {
3160   off_t startoff = off;
3161   off_t maxoff = off;
3162
3163   for (Section_list::iterator p = this->unattached_section_list_.begin();
3164        p != this->unattached_section_list_.end();
3165        ++p)
3166     {
3167       // The symtab section is handled in create_symtab_sections.
3168       if (*p == this->symtab_section_)
3169         continue;
3170
3171       // If we've already set the data size, don't set it again.
3172       if ((*p)->is_offset_valid() && (*p)->is_data_size_valid())
3173         continue;
3174
3175       if (pass == BEFORE_INPUT_SECTIONS_PASS
3176           && (*p)->requires_postprocessing())
3177         {
3178           (*p)->create_postprocessing_buffer();
3179           this->any_postprocessing_sections_ = true;
3180         }
3181
3182       if (pass == BEFORE_INPUT_SECTIONS_PASS
3183           && (*p)->after_input_sections())
3184         continue;
3185       else if (pass == POSTPROCESSING_SECTIONS_PASS
3186                && (!(*p)->after_input_sections()
3187                    || (*p)->type() == elfcpp::SHT_STRTAB))
3188         continue;
3189       else if (pass == STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
3190                && (!(*p)->after_input_sections()
3191                    || (*p)->type() != elfcpp::SHT_STRTAB))
3192         continue;
3193
3194       if (!parameters->incremental_update())
3195         {
3196           off = align_address(off, (*p)->addralign());
3197           (*p)->set_file_offset(off);
3198           (*p)->finalize_data_size();
3199         }
3200       else
3201         {
3202           // Incremental update: allocate file space from free list.
3203           (*p)->pre_finalize_data_size();
3204           off_t current_size = (*p)->current_data_size();
3205           off = this->allocate(current_size, (*p)->addralign(), startoff);
3206           if (off == -1)
3207             {
3208               if (is_debugging_enabled(DEBUG_INCREMENTAL))
3209                 this->free_list_.dump();
3210               gold_assert((*p)->output_section() != NULL);
3211               gold_fallback(_("out of patch space for section %s; "
3212                               "relink with --incremental-full"),
3213                             (*p)->output_section()->name());
3214             }
3215           (*p)->set_file_offset(off);
3216           (*p)->finalize_data_size();
3217           if ((*p)->data_size() > current_size)
3218             {
3219               gold_assert((*p)->output_section() != NULL);
3220               gold_fallback(_("%s: section changed size; "
3221                               "relink with --incremental-full"),
3222                             (*p)->output_section()->name());
3223             }
3224           gold_debug(DEBUG_INCREMENTAL,
3225                      "set_section_offsets: %08lx %08lx %s",
3226                      static_cast<long>(off),
3227                      static_cast<long>((*p)->data_size()),
3228                      ((*p)->output_section() != NULL
3229                       ? (*p)->output_section()->name() : "(special)"));
3230         }
3231
3232       off += (*p)->data_size();
3233       if (off > maxoff)
3234         maxoff = off;
3235
3236       // At this point the name must be set.
3237       if (pass != STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS)
3238         this->namepool_.add((*p)->name(), false, NULL);
3239     }
3240   return maxoff;
3241 }
3242
3243 // Set the section indexes of all the sections not associated with a
3244 // segment.
3245
3246 unsigned int
3247 Layout::set_section_indexes(unsigned int shndx)
3248 {
3249   for (Section_list::iterator p = this->unattached_section_list_.begin();
3250        p != this->unattached_section_list_.end();
3251        ++p)
3252     {
3253       if (!(*p)->has_out_shndx())
3254         {
3255           (*p)->set_out_shndx(shndx);
3256           ++shndx;
3257         }
3258     }
3259   return shndx;
3260 }
3261
3262 // Set the section addresses according to the linker script.  This is
3263 // only called when we see a SECTIONS clause.  This returns the
3264 // program segment which should hold the file header and segment
3265 // headers, if any.  It will return NULL if they should not be in a
3266 // segment.
3267
3268 Output_segment*
3269 Layout::set_section_addresses_from_script(Symbol_table* symtab)
3270 {
3271   Script_sections* ss = this->script_options_->script_sections();
3272   gold_assert(ss->saw_sections_clause());
3273   return this->script_options_->set_section_addresses(symtab, this);
3274 }
3275
3276 // Place the orphan sections in the linker script.
3277
3278 void
3279 Layout::place_orphan_sections_in_script()
3280 {
3281   Script_sections* ss = this->script_options_->script_sections();
3282   gold_assert(ss->saw_sections_clause());
3283
3284   // Place each orphaned output section in the script.
3285   for (Section_list::iterator p = this->section_list_.begin();
3286        p != this->section_list_.end();
3287        ++p)
3288     {
3289       if (!(*p)->found_in_sections_clause())
3290         ss->place_orphan(*p);
3291     }
3292 }
3293
3294 // Count the local symbols in the regular symbol table and the dynamic
3295 // symbol table, and build the respective string pools.
3296
3297 void
3298 Layout::count_local_symbols(const Task* task,
3299                             const Input_objects* input_objects)
3300 {
3301   // First, figure out an upper bound on the number of symbols we'll
3302   // be inserting into each pool.  This helps us create the pools with
3303   // the right size, to avoid unnecessary hashtable resizing.
3304   unsigned int symbol_count = 0;
3305   for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
3306        p != input_objects->relobj_end();
3307        ++p)
3308     symbol_count += (*p)->local_symbol_count();
3309
3310   // Go from "upper bound" to "estimate."  We overcount for two
3311   // reasons: we double-count symbols that occur in more than one
3312   // object file, and we count symbols that are dropped from the
3313   // output.  Add it all together and assume we overcount by 100%.
3314   symbol_count /= 2;
3315
3316   // We assume all symbols will go into both the sympool and dynpool.
3317   this->sympool_.reserve(symbol_count);
3318   this->dynpool_.reserve(symbol_count);
3319
3320   for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
3321        p != input_objects->relobj_end();
3322        ++p)
3323     {
3324       Task_lock_obj<Object> tlo(task, *p);
3325       (*p)->count_local_symbols(&this->sympool_, &this->dynpool_);
3326     }
3327 }
3328
3329 // Create the symbol table sections.  Here we also set the final
3330 // values of the symbols.  At this point all the loadable sections are
3331 // fully laid out.  SHNUM is the number of sections so far.
3332
3333 void
3334 Layout::create_symtab_sections(const Input_objects* input_objects,
3335                                Symbol_table* symtab,
3336                                unsigned int shnum,
3337                                off_t* poff)
3338 {
3339   int symsize;
3340   unsigned int align;
3341   if (parameters->target().get_size() == 32)
3342     {
3343       symsize = elfcpp::Elf_sizes<32>::sym_size;
3344       align = 4;
3345     }
3346   else if (parameters->target().get_size() == 64)
3347     {
3348       symsize = elfcpp::Elf_sizes<64>::sym_size;
3349       align = 8;
3350     }
3351   else
3352     gold_unreachable();
3353
3354   // Compute file offsets relative to the start of the symtab section.
3355   off_t off = 0;
3356
3357   // Save space for the dummy symbol at the start of the section.  We
3358   // never bother to write this out--it will just be left as zero.
3359   off += symsize;
3360   unsigned int local_symbol_index = 1;
3361
3362   // Add STT_SECTION symbols for each Output section which needs one.
3363   for (Section_list::iterator p = this->section_list_.begin();
3364        p != this->section_list_.end();
3365        ++p)
3366     {
3367       if (!(*p)->needs_symtab_index())
3368         (*p)->set_symtab_index(-1U);
3369       else
3370         {
3371           (*p)->set_symtab_index(local_symbol_index);
3372           ++local_symbol_index;
3373           off += symsize;
3374         }
3375     }
3376
3377   for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
3378        p != input_objects->relobj_end();
3379        ++p)
3380     {
3381       unsigned int index = (*p)->finalize_local_symbols(local_symbol_index,
3382                                                         off, symtab);
3383       off += (index - local_symbol_index) * symsize;
3384       local_symbol_index = index;
3385     }
3386
3387   unsigned int local_symcount = local_symbol_index;
3388   gold_assert(static_cast<off_t>(local_symcount * symsize) == off);
3389
3390   off_t dynoff;
3391   size_t dyn_global_index;
3392   size_t dyncount;
3393   if (this->dynsym_section_ == NULL)
3394     {
3395       dynoff = 0;
3396       dyn_global_index = 0;
3397       dyncount = 0;
3398     }
3399   else
3400     {
3401       dyn_global_index = this->dynsym_section_->info();
3402       off_t locsize = dyn_global_index * this->dynsym_section_->entsize();
3403       dynoff = this->dynsym_section_->offset() + locsize;
3404       dyncount = (this->dynsym_section_->data_size() - locsize) / symsize;
3405       gold_assert(static_cast<off_t>(dyncount * symsize)
3406                   == this->dynsym_section_->data_size() - locsize);
3407     }
3408
3409   off_t global_off = off;
3410   off = symtab->finalize(off, dynoff, dyn_global_index, dyncount,
3411                          &this->sympool_, &local_symcount);
3412
3413   if (!parameters->options().strip_all())
3414     {
3415       this->sympool_.set_string_offsets();
3416
3417       const char* symtab_name = this->namepool_.add(".symtab", false, NULL);
3418       Output_section* osymtab = this->make_output_section(symtab_name,
3419                                                           elfcpp::SHT_SYMTAB,
3420                                                           0, ORDER_INVALID,
3421                                                           false);
3422       this->symtab_section_ = osymtab;
3423
3424       Output_section_data* pos = new Output_data_fixed_space(off, align,
3425                                                              "** symtab");
3426       osymtab->add_output_section_data(pos);
3427
3428       // We generate a .symtab_shndx section if we have more than
3429       // SHN_LORESERVE sections.  Technically it is possible that we
3430       // don't need one, because it is possible that there are no
3431       // symbols in any of sections with indexes larger than
3432       // SHN_LORESERVE.  That is probably unusual, though, and it is
3433       // easier to always create one than to compute section indexes
3434       // twice (once here, once when writing out the symbols).
3435       if (shnum >= elfcpp::SHN_LORESERVE)
3436         {
3437           const char* symtab_xindex_name = this->namepool_.add(".symtab_shndx",
3438                                                                false, NULL);
3439           Output_section* osymtab_xindex =
3440             this->make_output_section(symtab_xindex_name,
3441                                       elfcpp::SHT_SYMTAB_SHNDX, 0,
3442                                       ORDER_INVALID, false);
3443
3444           size_t symcount = off / symsize;
3445           this->symtab_xindex_ = new Output_symtab_xindex(symcount);
3446
3447           osymtab_xindex->add_output_section_data(this->symtab_xindex_);
3448
3449           osymtab_xindex->set_link_section(osymtab);
3450           osymtab_xindex->set_addralign(4);
3451           osymtab_xindex->set_entsize(4);
3452
3453           osymtab_xindex->set_after_input_sections();
3454
3455           // This tells the driver code to wait until the symbol table
3456           // has written out before writing out the postprocessing
3457           // sections, including the .symtab_shndx section.
3458           this->any_postprocessing_sections_ = true;
3459         }
3460
3461       const char* strtab_name = this->namepool_.add(".strtab", false, NULL);
3462       Output_section* ostrtab = this->make_output_section(strtab_name,
3463                                                           elfcpp::SHT_STRTAB,
3464                                                           0, ORDER_INVALID,
3465                                                           false);
3466
3467       Output_section_data* pstr = new Output_data_strtab(&this->sympool_);
3468       ostrtab->add_output_section_data(pstr);
3469
3470       off_t symtab_off;
3471       if (!parameters->incremental_update())
3472         symtab_off = align_address(*poff, align);
3473       else
3474         {
3475           symtab_off = this->allocate(off, align, *poff);
3476           if (off == -1)
3477             gold_fallback(_("out of patch space for symbol table; "
3478                             "relink with --incremental-full"));
3479           gold_debug(DEBUG_INCREMENTAL,
3480                      "create_symtab_sections: %08lx %08lx .symtab",
3481                      static_cast<long>(symtab_off),
3482                      static_cast<long>(off));
3483         }
3484
3485       symtab->set_file_offset(symtab_off + global_off);
3486       osymtab->set_file_offset(symtab_off);
3487       osymtab->finalize_data_size();
3488       osymtab->set_link_section(ostrtab);
3489       osymtab->set_info(local_symcount);
3490       osymtab->set_entsize(symsize);
3491
3492       if (symtab_off + off > *poff)
3493         *poff = symtab_off + off;
3494     }
3495 }
3496
3497 // Create the .shstrtab section, which holds the names of the
3498 // sections.  At the time this is called, we have created all the
3499 // output sections except .shstrtab itself.
3500
3501 Output_section*
3502 Layout::create_shstrtab()
3503 {
3504   // FIXME: We don't need to create a .shstrtab section if we are
3505   // stripping everything.
3506
3507   const char* name = this->namepool_.add(".shstrtab", false, NULL);
3508
3509   Output_section* os = this->make_output_section(name, elfcpp::SHT_STRTAB, 0,
3510                                                  ORDER_INVALID, false);
3511
3512   if (strcmp(parameters->options().compress_debug_sections(), "none") != 0)
3513     {
3514       // We can't write out this section until we've set all the
3515       // section names, and we don't set the names of compressed
3516       // output sections until relocations are complete.  FIXME: With
3517       // the current names we use, this is unnecessary.
3518       os->set_after_input_sections();
3519     }
3520
3521   Output_section_data* posd = new Output_data_strtab(&this->namepool_);
3522   os->add_output_section_data(posd);
3523
3524   return os;
3525 }
3526
3527 // Create the section headers.  SIZE is 32 or 64.  OFF is the file
3528 // offset.
3529
3530 void
3531 Layout::create_shdrs(const Output_section* shstrtab_section, off_t* poff)
3532 {
3533   Output_section_headers* oshdrs;
3534   oshdrs = new Output_section_headers(this,
3535                                       &this->segment_list_,
3536                                       &this->section_list_,
3537                                       &this->unattached_section_list_,
3538                                       &this->namepool_,
3539                                       shstrtab_section);
3540   off_t off;
3541   if (!parameters->incremental_update())
3542     off = align_address(*poff, oshdrs->addralign());
3543   else
3544     {
3545       oshdrs->pre_finalize_data_size();
3546       off = this->allocate(oshdrs->data_size(), oshdrs->addralign(), *poff);
3547       if (off == -1)
3548           gold_fallback(_("out of patch space for section header table; "
3549                           "relink with --incremental-full"));
3550       gold_debug(DEBUG_INCREMENTAL,
3551                  "create_shdrs: %08lx %08lx (section header table)",
3552                  static_cast<long>(off),
3553                  static_cast<long>(off + oshdrs->data_size()));
3554     }
3555   oshdrs->set_address_and_file_offset(0, off);
3556   off += oshdrs->data_size();
3557   if (off > *poff)
3558     *poff = off;
3559   this->section_headers_ = oshdrs;
3560 }
3561
3562 // Count the allocated sections.
3563
3564 size_t
3565 Layout::allocated_output_section_count() const
3566 {
3567   size_t section_count = 0;
3568   for (Segment_list::const_iterator p = this->segment_list_.begin();
3569        p != this->segment_list_.end();
3570        ++p)
3571     section_count += (*p)->output_section_count();
3572   return section_count;
3573 }
3574
3575 // Create the dynamic symbol table.
3576
3577 void
3578 Layout::create_dynamic_symtab(const Input_objects* input_objects,
3579                               Symbol_table* symtab,
3580                               Output_section** pdynstr,
3581                               unsigned int* plocal_dynamic_count,
3582                               std::vector<Symbol*>* pdynamic_symbols,
3583                               Versions* pversions)
3584 {
3585   // Count all the symbols in the dynamic symbol table, and set the
3586   // dynamic symbol indexes.
3587
3588   // Skip symbol 0, which is always all zeroes.
3589   unsigned int index = 1;
3590
3591   // Add STT_SECTION symbols for each Output section which needs one.
3592   for (Section_list::iterator p = this->section_list_.begin();
3593        p != this->section_list_.end();
3594        ++p)
3595     {
3596       if (!(*p)->needs_dynsym_index())
3597         (*p)->set_dynsym_index(-1U);
3598       else
3599         {
3600           (*p)->set_dynsym_index(index);
3601           ++index;
3602         }
3603     }
3604
3605   // Count the local symbols that need to go in the dynamic symbol table,
3606   // and set the dynamic symbol indexes.
3607   for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
3608        p != input_objects->relobj_end();
3609        ++p)
3610     {
3611       unsigned int new_index = (*p)->set_local_dynsym_indexes(index);
3612       index = new_index;
3613     }
3614
3615   unsigned int local_symcount = index;
3616   *plocal_dynamic_count = local_symcount;
3617
3618   index = symtab->set_dynsym_indexes(index, pdynamic_symbols,
3619                                      &this->dynpool_, pversions);
3620
3621   int symsize;
3622   unsigned int align;
3623   const int size = parameters->target().get_size();
3624   if (size == 32)
3625     {
3626       symsize = elfcpp::Elf_sizes<32>::sym_size;
3627       align = 4;
3628     }
3629   else if (size == 64)
3630     {
3631       symsize = elfcpp::Elf_sizes<64>::sym_size;
3632       align = 8;
3633     }
3634   else
3635     gold_unreachable();
3636
3637   // Create the dynamic symbol table section.
3638
3639   Output_section* dynsym = this->choose_output_section(NULL, ".dynsym",
3640                                                        elfcpp::SHT_DYNSYM,
3641                                                        elfcpp::SHF_ALLOC,
3642                                                        false,
3643                                                        ORDER_DYNAMIC_LINKER,
3644                                                        false);
3645
3646   Output_section_data* odata = new Output_data_fixed_space(index * symsize,
3647                                                            align,
3648                                                            "** dynsym");
3649   dynsym->add_output_section_data(odata);
3650
3651   dynsym->set_info(local_symcount);
3652   dynsym->set_entsize(symsize);
3653   dynsym->set_addralign(align);
3654
3655   this->dynsym_section_ = dynsym;
3656
3657   Output_data_dynamic* const odyn = this->dynamic_data_;
3658   odyn->add_section_address(elfcpp::DT_SYMTAB, dynsym);
3659   odyn->add_constant(elfcpp::DT_SYMENT, symsize);
3660
3661   // If there are more than SHN_LORESERVE allocated sections, we
3662   // create a .dynsym_shndx section.  It is possible that we don't
3663   // need one, because it is possible that there are no dynamic
3664   // symbols in any of the sections with indexes larger than
3665   // SHN_LORESERVE.  This is probably unusual, though, and at this
3666   // time we don't know the actual section indexes so it is
3667   // inconvenient to check.
3668   if (this->allocated_output_section_count() >= elfcpp::SHN_LORESERVE)
3669     {
3670       Output_section* dynsym_xindex =
3671         this->choose_output_section(NULL, ".dynsym_shndx",
3672                                     elfcpp::SHT_SYMTAB_SHNDX,
3673                                     elfcpp::SHF_ALLOC,
3674                                     false, ORDER_DYNAMIC_LINKER, false);
3675
3676       this->dynsym_xindex_ = new Output_symtab_xindex(index);
3677
3678       dynsym_xindex->add_output_section_data(this->dynsym_xindex_);
3679
3680       dynsym_xindex->set_link_section(dynsym);
3681       dynsym_xindex->set_addralign(4);
3682       dynsym_xindex->set_entsize(4);
3683
3684       dynsym_xindex->set_after_input_sections();
3685
3686       // This tells the driver code to wait until the symbol table has
3687       // written out before writing out the postprocessing sections,
3688       // including the .dynsym_shndx section.
3689       this->any_postprocessing_sections_ = true;
3690     }
3691
3692   // Create the dynamic string table section.
3693
3694   Output_section* dynstr = this->choose_output_section(NULL, ".dynstr",
3695                                                        elfcpp::SHT_STRTAB,
3696                                                        elfcpp::SHF_ALLOC,
3697                                                        false,
3698                                                        ORDER_DYNAMIC_LINKER,
3699                                                        false);
3700
3701   Output_section_data* strdata = new Output_data_strtab(&this->dynpool_);
3702   dynstr->add_output_section_data(strdata);
3703
3704   dynsym->set_link_section(dynstr);
3705   this->dynamic_section_->set_link_section(dynstr);
3706
3707   odyn->add_section_address(elfcpp::DT_STRTAB, dynstr);
3708   odyn->add_section_size(elfcpp::DT_STRSZ, dynstr);
3709
3710   *pdynstr = dynstr;
3711
3712   // Create the hash tables.
3713
3714   if (strcmp(parameters->options().hash_style(), "sysv") == 0
3715       || strcmp(parameters->options().hash_style(), "both") == 0)
3716     {
3717       unsigned char* phash;
3718       unsigned int hashlen;
3719       Dynobj::create_elf_hash_table(*pdynamic_symbols, local_symcount,
3720                                     &phash, &hashlen);
3721
3722       Output_section* hashsec =
3723         this->choose_output_section(NULL, ".hash", elfcpp::SHT_HASH,
3724                                     elfcpp::SHF_ALLOC, false,
3725                                     ORDER_DYNAMIC_LINKER, false);
3726
3727       Output_section_data* hashdata = new Output_data_const_buffer(phash,
3728                                                                    hashlen,
3729                                                                    align,
3730                                                                    "** hash");
3731       hashsec->add_output_section_data(hashdata);
3732
3733       hashsec->set_link_section(dynsym);
3734       hashsec->set_entsize(4);
3735
3736       odyn->add_section_address(elfcpp::DT_HASH, hashsec);
3737     }
3738
3739   if (strcmp(parameters->options().hash_style(), "gnu") == 0
3740       || strcmp(parameters->options().hash_style(), "both") == 0)
3741     {
3742       unsigned char* phash;
3743       unsigned int hashlen;
3744       Dynobj::create_gnu_hash_table(*pdynamic_symbols, local_symcount,
3745                                     &phash, &hashlen);
3746
3747       Output_section* hashsec =
3748         this->choose_output_section(NULL, ".gnu.hash", elfcpp::SHT_GNU_HASH,
3749                                     elfcpp::SHF_ALLOC, false,
3750                                     ORDER_DYNAMIC_LINKER, false);
3751
3752       Output_section_data* hashdata = new Output_data_const_buffer(phash,
3753                                                                    hashlen,
3754                                                                    align,
3755                                                                    "** hash");
3756       hashsec->add_output_section_data(hashdata);
3757
3758       hashsec->set_link_section(dynsym);
3759
3760       // For a 64-bit target, the entries in .gnu.hash do not have a
3761       // uniform size, so we only set the entry size for a 32-bit
3762       // target.
3763       if (parameters->target().get_size() == 32)
3764         hashsec->set_entsize(4);
3765
3766       odyn->add_section_address(elfcpp::DT_GNU_HASH, hashsec);
3767     }
3768 }
3769
3770 // Assign offsets to each local portion of the dynamic symbol table.
3771
3772 void
3773 Layout::assign_local_dynsym_offsets(const Input_objects* input_objects)
3774 {
3775   Output_section* dynsym = this->dynsym_section_;
3776   gold_assert(dynsym != NULL);
3777
3778   off_t off = dynsym->offset();
3779
3780   // Skip the dummy symbol at the start of the section.
3781   off += dynsym->entsize();
3782
3783   for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
3784        p != input_objects->relobj_end();
3785        ++p)
3786     {
3787       unsigned int count = (*p)->set_local_dynsym_offset(off);
3788       off += count * dynsym->entsize();
3789     }
3790 }
3791
3792 // Create the version sections.
3793
3794 void
3795 Layout::create_version_sections(const Versions* versions,
3796                                 const Symbol_table* symtab,
3797                                 unsigned int local_symcount,
3798                                 const std::vector<Symbol*>& dynamic_symbols,
3799                                 const Output_section* dynstr)
3800 {
3801   if (!versions->any_defs() && !versions->any_needs())
3802     return;
3803
3804   switch (parameters->size_and_endianness())
3805     {
3806 #ifdef HAVE_TARGET_32_LITTLE
3807     case Parameters::TARGET_32_LITTLE:
3808       this->sized_create_version_sections<32, false>(versions, symtab,
3809                                                      local_symcount,
3810                                                      dynamic_symbols, dynstr);
3811       break;
3812 #endif
3813 #ifdef HAVE_TARGET_32_BIG
3814     case Parameters::TARGET_32_BIG:
3815       this->sized_create_version_sections<32, true>(versions, symtab,
3816                                                     local_symcount,
3817                                                     dynamic_symbols, dynstr);
3818       break;
3819 #endif
3820 #ifdef HAVE_TARGET_64_LITTLE
3821     case Parameters::TARGET_64_LITTLE:
3822       this->sized_create_version_sections<64, false>(versions, symtab,
3823                                                      local_symcount,
3824                                                      dynamic_symbols, dynstr);
3825       break;
3826 #endif
3827 #ifdef HAVE_TARGET_64_BIG
3828     case Parameters::TARGET_64_BIG:
3829       this->sized_create_version_sections<64, true>(versions, symtab,
3830                                                     local_symcount,
3831                                                     dynamic_symbols, dynstr);
3832       break;
3833 #endif
3834     default:
3835       gold_unreachable();
3836     }
3837 }
3838
3839 // Create the version sections, sized version.
3840
3841 template<int size, bool big_endian>
3842 void
3843 Layout::sized_create_version_sections(
3844     const Versions* versions,
3845     const Symbol_table* symtab,
3846     unsigned int local_symcount,
3847     const std::vector<Symbol*>& dynamic_symbols,
3848     const Output_section* dynstr)
3849 {
3850   Output_section* vsec = this->choose_output_section(NULL, ".gnu.version",
3851                                                      elfcpp::SHT_GNU_versym,
3852                                                      elfcpp::SHF_ALLOC,
3853                                                      false,
3854                                                      ORDER_DYNAMIC_LINKER,
3855                                                      false);
3856
3857   unsigned char* vbuf;
3858   unsigned int vsize;
3859   versions->symbol_section_contents<size, big_endian>(symtab, &this->dynpool_,
3860                                                       local_symcount,
3861                                                       dynamic_symbols,
3862                                                       &vbuf, &vsize);
3863
3864   Output_section_data* vdata = new Output_data_const_buffer(vbuf, vsize, 2,
3865                                                             "** versions");
3866
3867   vsec->add_output_section_data(vdata);
3868   vsec->set_entsize(2);
3869   vsec->set_link_section(this->dynsym_section_);
3870
3871   Output_data_dynamic* const odyn = this->dynamic_data_;
3872   odyn->add_section_address(elfcpp::DT_VERSYM, vsec);
3873
3874   if (versions->any_defs())
3875     {
3876       Output_section* vdsec;
3877       vdsec= this->choose_output_section(NULL, ".gnu.version_d",
3878                                          elfcpp::SHT_GNU_verdef,
3879                                          elfcpp::SHF_ALLOC,
3880                                          false, ORDER_DYNAMIC_LINKER, false);
3881
3882       unsigned char* vdbuf;
3883       unsigned int vdsize;
3884       unsigned int vdentries;
3885       versions->def_section_contents<size, big_endian>(&this->dynpool_, &vdbuf,
3886                                                        &vdsize, &vdentries);
3887
3888       Output_section_data* vddata =
3889         new Output_data_const_buffer(vdbuf, vdsize, 4, "** version defs");
3890
3891       vdsec->add_output_section_data(vddata);
3892       vdsec->set_link_section(dynstr);
3893       vdsec->set_info(vdentries);
3894
3895       odyn->add_section_address(elfcpp::DT_VERDEF, vdsec);
3896       odyn->add_constant(elfcpp::DT_VERDEFNUM, vdentries);
3897     }
3898
3899   if (versions->any_needs())
3900     {
3901       Output_section* vnsec;
3902       vnsec = this->choose_output_section(NULL, ".gnu.version_r",
3903                                           elfcpp::SHT_GNU_verneed,
3904                                           elfcpp::SHF_ALLOC,
3905                                           false, ORDER_DYNAMIC_LINKER, false);
3906
3907       unsigned char* vnbuf;
3908       unsigned int vnsize;
3909       unsigned int vnentries;
3910       versions->need_section_contents<size, big_endian>(&this->dynpool_,
3911                                                         &vnbuf, &vnsize,
3912                                                         &vnentries);
3913
3914       Output_section_data* vndata =
3915         new Output_data_const_buffer(vnbuf, vnsize, 4, "** version refs");
3916
3917       vnsec->add_output_section_data(vndata);
3918       vnsec->set_link_section(dynstr);
3919       vnsec->set_info(vnentries);
3920
3921       odyn->add_section_address(elfcpp::DT_VERNEED, vnsec);
3922       odyn->add_constant(elfcpp::DT_VERNEEDNUM, vnentries);
3923     }
3924 }
3925
3926 // Create the .interp section and PT_INTERP segment.
3927
3928 void
3929 Layout::create_interp(const Target* target)
3930 {
3931   gold_assert(this->interp_segment_ == NULL);
3932
3933   const char* interp = parameters->options().dynamic_linker();
3934   if (interp == NULL)
3935     {
3936       interp = target->dynamic_linker();
3937       gold_assert(interp != NULL);
3938     }
3939
3940   size_t len = strlen(interp) + 1;
3941
3942   Output_section_data* odata = new Output_data_const(interp, len, 1);
3943
3944   Output_section* osec = this->choose_output_section(NULL, ".interp",
3945                                                      elfcpp::SHT_PROGBITS,
3946                                                      elfcpp::SHF_ALLOC,
3947                                                      false, ORDER_INTERP,
3948                                                      false);
3949   osec->add_output_section_data(odata);
3950 }
3951
3952 // Add dynamic tags for the PLT and the dynamic relocs.  This is
3953 // called by the target-specific code.  This does nothing if not doing
3954 // a dynamic link.
3955
3956 // USE_REL is true for REL relocs rather than RELA relocs.
3957
3958 // If PLT_GOT is not NULL, then DT_PLTGOT points to it.
3959
3960 // If PLT_REL is not NULL, it is used for DT_PLTRELSZ, and DT_JMPREL,
3961 // and we also set DT_PLTREL.  We use PLT_REL's output section, since
3962 // some targets have multiple reloc sections in PLT_REL.
3963
3964 // If DYN_REL is not NULL, it is used for DT_REL/DT_RELA,
3965 // DT_RELSZ/DT_RELASZ, DT_RELENT/DT_RELAENT.
3966
3967 // If ADD_DEBUG is true, we add a DT_DEBUG entry when generating an
3968 // executable.
3969
3970 void
3971 Layout::add_target_dynamic_tags(bool use_rel, const Output_data* plt_got,
3972                                 const Output_data* plt_rel,
3973                                 const Output_data_reloc_generic* dyn_rel,
3974                                 bool add_debug, bool dynrel_includes_plt)
3975 {
3976   Output_data_dynamic* odyn = this->dynamic_data_;
3977   if (odyn == NULL)
3978     return;
3979
3980   if (plt_got != NULL && plt_got->output_section() != NULL)
3981     odyn->add_section_address(elfcpp::DT_PLTGOT, plt_got);
3982
3983   if (plt_rel != NULL && plt_rel->output_section() != NULL)
3984     {
3985       odyn->add_section_size(elfcpp::DT_PLTRELSZ, plt_rel->output_section());
3986       odyn->add_section_address(elfcpp::DT_JMPREL, plt_rel->output_section());
3987       odyn->add_constant(elfcpp::DT_PLTREL,
3988                          use_rel ? elfcpp::DT_REL : elfcpp::DT_RELA);
3989     }
3990
3991   if (dyn_rel != NULL && dyn_rel->output_section() != NULL)
3992     {
3993       odyn->add_section_address(use_rel ? elfcpp::DT_REL : elfcpp::DT_RELA,
3994                                 dyn_rel);
3995       if (plt_rel != NULL && dynrel_includes_plt)
3996         odyn->add_section_size(use_rel ? elfcpp::DT_RELSZ : elfcpp::DT_RELASZ,
3997                                dyn_rel, plt_rel);
3998       else
3999         odyn->add_section_size(use_rel ? elfcpp::DT_RELSZ : elfcpp::DT_RELASZ,
4000                                dyn_rel);
4001       const int size = parameters->target().get_size();
4002       elfcpp::DT rel_tag;
4003       int rel_size;
4004       if (use_rel)
4005         {
4006           rel_tag = elfcpp::DT_RELENT;
4007           if (size == 32)
4008             rel_size = Reloc_types<elfcpp::SHT_REL, 32, false>::reloc_size;
4009           else if (size == 64)
4010             rel_size = Reloc_types<elfcpp::SHT_REL, 64, false>::reloc_size;
4011           else
4012             gold_unreachable();
4013         }
4014       else
4015         {
4016           rel_tag = elfcpp::DT_RELAENT;
4017           if (size == 32)
4018             rel_size = Reloc_types<elfcpp::SHT_RELA, 32, false>::reloc_size;
4019           else if (size == 64)
4020             rel_size = Reloc_types<elfcpp::SHT_RELA, 64, false>::reloc_size;
4021           else
4022             gold_unreachable();
4023         }
4024       odyn->add_constant(rel_tag, rel_size);
4025
4026       if (parameters->options().combreloc())
4027         {
4028           size_t c = dyn_rel->relative_reloc_count();
4029           if (c > 0)
4030             odyn->add_constant((use_rel
4031                                 ? elfcpp::DT_RELCOUNT
4032                                 : elfcpp::DT_RELACOUNT),
4033                                c);
4034         }
4035     }
4036
4037   if (add_debug && !parameters->options().shared())
4038     {
4039       // The value of the DT_DEBUG tag is filled in by the dynamic
4040       // linker at run time, and used by the debugger.
4041       odyn->add_constant(elfcpp::DT_DEBUG, 0);
4042     }
4043 }
4044
4045 // Finish the .dynamic section and PT_DYNAMIC segment.
4046
4047 void
4048 Layout::finish_dynamic_section(const Input_objects* input_objects,
4049                                const Symbol_table* symtab)
4050 {
4051   if (!this->script_options_->saw_phdrs_clause())
4052     {
4053       Output_segment* oseg = this->make_output_segment(elfcpp::PT_DYNAMIC,
4054                                                        (elfcpp::PF_R
4055                                                         | elfcpp::PF_W));
4056       oseg->add_output_section_to_nonload(this->dynamic_section_,
4057                                           elfcpp::PF_R | elfcpp::PF_W);
4058     }
4059
4060   Output_data_dynamic* const odyn = this->dynamic_data_;
4061
4062   for (Input_objects::Dynobj_iterator p = input_objects->dynobj_begin();
4063        p != input_objects->dynobj_end();
4064        ++p)
4065     {
4066       if (!(*p)->is_needed() && (*p)->as_needed())
4067         {
4068           // This dynamic object was linked with --as-needed, but it
4069           // is not needed.
4070           continue;
4071         }
4072
4073       odyn->add_string(elfcpp::DT_NEEDED, (*p)->soname());
4074     }
4075
4076   if (parameters->options().shared())
4077     {
4078       const char* soname = parameters->options().soname();
4079       if (soname != NULL)
4080         odyn->add_string(elfcpp::DT_SONAME, soname);
4081     }
4082
4083   Symbol* sym = symtab->lookup(parameters->options().init());
4084   if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj())
4085     odyn->add_symbol(elfcpp::DT_INIT, sym);
4086
4087   sym = symtab->lookup(parameters->options().fini());
4088   if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj())
4089     odyn->add_symbol(elfcpp::DT_FINI, sym);
4090
4091   // Look for .init_array, .preinit_array and .fini_array by checking
4092   // section types.
4093   for(Layout::Section_list::const_iterator p = this->section_list_.begin();
4094       p != this->section_list_.end();
4095       ++p)
4096     switch((*p)->type())
4097       {
4098       case elfcpp::SHT_FINI_ARRAY:
4099         odyn->add_section_address(elfcpp::DT_FINI_ARRAY, *p);
4100         odyn->add_section_size(elfcpp::DT_FINI_ARRAYSZ, *p); 
4101         break;
4102       case elfcpp::SHT_INIT_ARRAY:
4103         odyn->add_section_address(elfcpp::DT_INIT_ARRAY, *p);
4104         odyn->add_section_size(elfcpp::DT_INIT_ARRAYSZ, *p); 
4105         break;
4106       case elfcpp::SHT_PREINIT_ARRAY:
4107         odyn->add_section_address(elfcpp::DT_PREINIT_ARRAY, *p);
4108         odyn->add_section_size(elfcpp::DT_PREINIT_ARRAYSZ, *p); 
4109         break;
4110       default:
4111         break;
4112       }
4113   
4114   // Add a DT_RPATH entry if needed.
4115   const General_options::Dir_list& rpath(parameters->options().rpath());
4116   if (!rpath.empty())
4117     {
4118       std::string rpath_val;
4119       for (General_options::Dir_list::const_iterator p = rpath.begin();
4120            p != rpath.end();
4121            ++p)
4122         {
4123           if (rpath_val.empty())
4124             rpath_val = p->name();
4125           else
4126             {
4127               // Eliminate duplicates.
4128               General_options::Dir_list::const_iterator q;
4129               for (q = rpath.begin(); q != p; ++q)
4130                 if (q->name() == p->name())
4131                   break;
4132               if (q == p)
4133                 {
4134                   rpath_val += ':';
4135                   rpath_val += p->name();
4136                 }
4137             }
4138         }
4139
4140       odyn->add_string(elfcpp::DT_RPATH, rpath_val);
4141       if (parameters->options().enable_new_dtags())
4142         odyn->add_string(elfcpp::DT_RUNPATH, rpath_val);
4143     }
4144
4145   // Look for text segments that have dynamic relocations.
4146   bool have_textrel = false;
4147   if (!this->script_options_->saw_sections_clause())
4148     {
4149       for (Segment_list::const_iterator p = this->segment_list_.begin();
4150            p != this->segment_list_.end();
4151            ++p)
4152         {
4153           if ((*p)->type() == elfcpp::PT_LOAD
4154               && ((*p)->flags() & elfcpp::PF_W) == 0
4155               && (*p)->has_dynamic_reloc())
4156             {
4157               have_textrel = true;
4158               break;
4159             }
4160         }
4161     }
4162   else
4163     {
4164       // We don't know the section -> segment mapping, so we are
4165       // conservative and just look for readonly sections with
4166       // relocations.  If those sections wind up in writable segments,
4167       // then we have created an unnecessary DT_TEXTREL entry.
4168       for (Section_list::const_iterator p = this->section_list_.begin();
4169            p != this->section_list_.end();
4170            ++p)
4171         {
4172           if (((*p)->flags() & elfcpp::SHF_ALLOC) != 0
4173               && ((*p)->flags() & elfcpp::SHF_WRITE) == 0
4174               && (*p)->has_dynamic_reloc())
4175             {
4176               have_textrel = true;
4177               break;
4178             }
4179         }
4180     }
4181
4182   // Add a DT_FLAGS entry. We add it even if no flags are set so that
4183   // post-link tools can easily modify these flags if desired.
4184   unsigned int flags = 0;
4185   if (have_textrel)
4186     {
4187       // Add a DT_TEXTREL for compatibility with older loaders.
4188       odyn->add_constant(elfcpp::DT_TEXTREL, 0);
4189       flags |= elfcpp::DF_TEXTREL;
4190
4191       if (parameters->options().text())
4192         gold_error(_("read-only segment has dynamic relocations"));
4193       else if (parameters->options().warn_shared_textrel()
4194                && parameters->options().shared())
4195         gold_warning(_("shared library text segment is not shareable"));
4196     }
4197   if (parameters->options().shared() && this->has_static_tls())
4198     flags |= elfcpp::DF_STATIC_TLS;
4199   if (parameters->options().origin())
4200     flags |= elfcpp::DF_ORIGIN;
4201   if (parameters->options().Bsymbolic())
4202     {
4203       flags |= elfcpp::DF_SYMBOLIC;
4204       // Add DT_SYMBOLIC for compatibility with older loaders.
4205       odyn->add_constant(elfcpp::DT_SYMBOLIC, 0);
4206     }
4207   if (parameters->options().now())
4208     flags |= elfcpp::DF_BIND_NOW;
4209   if (flags != 0)
4210     odyn->add_constant(elfcpp::DT_FLAGS, flags);
4211
4212   flags = 0;
4213   if (parameters->options().initfirst())
4214     flags |= elfcpp::DF_1_INITFIRST;
4215   if (parameters->options().interpose())
4216     flags |= elfcpp::DF_1_INTERPOSE;
4217   if (parameters->options().loadfltr())
4218     flags |= elfcpp::DF_1_LOADFLTR;
4219   if (parameters->options().nodefaultlib())
4220     flags |= elfcpp::DF_1_NODEFLIB;
4221   if (parameters->options().nodelete())
4222     flags |= elfcpp::DF_1_NODELETE;
4223   if (parameters->options().nodlopen())
4224     flags |= elfcpp::DF_1_NOOPEN;
4225   if (parameters->options().nodump())
4226     flags |= elfcpp::DF_1_NODUMP;
4227   if (!parameters->options().shared())
4228     flags &= ~(elfcpp::DF_1_INITFIRST
4229                | elfcpp::DF_1_NODELETE
4230                | elfcpp::DF_1_NOOPEN);
4231   if (parameters->options().origin())
4232     flags |= elfcpp::DF_1_ORIGIN;
4233   if (parameters->options().now())
4234     flags |= elfcpp::DF_1_NOW;
4235   if (flags != 0)
4236     odyn->add_constant(elfcpp::DT_FLAGS_1, flags);
4237 }
4238
4239 // Set the size of the _DYNAMIC symbol table to be the size of the
4240 // dynamic data.
4241
4242 void
4243 Layout::set_dynamic_symbol_size(const Symbol_table* symtab)
4244 {
4245   Output_data_dynamic* const odyn = this->dynamic_data_;
4246   odyn->finalize_data_size();
4247   off_t data_size = odyn->data_size();
4248   const int size = parameters->target().get_size();
4249   if (size == 32)
4250     symtab->get_sized_symbol<32>(this->dynamic_symbol_)->set_symsize(data_size);
4251   else if (size == 64)
4252     symtab->get_sized_symbol<64>(this->dynamic_symbol_)->set_symsize(data_size);
4253   else
4254     gold_unreachable();
4255 }
4256
4257 // The mapping of input section name prefixes to output section names.
4258 // In some cases one prefix is itself a prefix of another prefix; in
4259 // such a case the longer prefix must come first.  These prefixes are
4260 // based on the GNU linker default ELF linker script.
4261
4262 #define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 }
4263 const Layout::Section_name_mapping Layout::section_name_mapping[] =
4264 {
4265   MAPPING_INIT(".text.", ".text"),
4266   MAPPING_INIT(".rodata.", ".rodata"),
4267   MAPPING_INIT(".data.rel.ro.local", ".data.rel.ro.local"),
4268   MAPPING_INIT(".data.rel.ro", ".data.rel.ro"),
4269   MAPPING_INIT(".data.", ".data"),
4270   MAPPING_INIT(".bss.", ".bss"),
4271   MAPPING_INIT(".tdata.", ".tdata"),
4272   MAPPING_INIT(".tbss.", ".tbss"),
4273   MAPPING_INIT(".init_array.", ".init_array"),
4274   MAPPING_INIT(".fini_array.", ".fini_array"),
4275   MAPPING_INIT(".sdata.", ".sdata"),
4276   MAPPING_INIT(".sbss.", ".sbss"),
4277   // FIXME: In the GNU linker, .sbss2 and .sdata2 are handled
4278   // differently depending on whether it is creating a shared library.
4279   MAPPING_INIT(".sdata2.", ".sdata"),
4280   MAPPING_INIT(".sbss2.", ".sbss"),
4281   MAPPING_INIT(".lrodata.", ".lrodata"),
4282   MAPPING_INIT(".ldata.", ".ldata"),
4283   MAPPING_INIT(".lbss.", ".lbss"),
4284   MAPPING_INIT(".gcc_except_table.", ".gcc_except_table"),
4285   MAPPING_INIT(".gnu.linkonce.d.rel.ro.local.", ".data.rel.ro.local"),
4286   MAPPING_INIT(".gnu.linkonce.d.rel.ro.", ".data.rel.ro"),
4287   MAPPING_INIT(".gnu.linkonce.t.", ".text"),
4288   MAPPING_INIT(".gnu.linkonce.r.", ".rodata"),
4289   MAPPING_INIT(".gnu.linkonce.d.", ".data"),
4290   MAPPING_INIT(".gnu.linkonce.b.", ".bss"),
4291   MAPPING_INIT(".gnu.linkonce.s.", ".sdata"),
4292   MAPPING_INIT(".gnu.linkonce.sb.", ".sbss"),
4293   MAPPING_INIT(".gnu.linkonce.s2.", ".sdata"),
4294   MAPPING_INIT(".gnu.linkonce.sb2.", ".sbss"),
4295   MAPPING_INIT(".gnu.linkonce.wi.", ".debug_info"),
4296   MAPPING_INIT(".gnu.linkonce.td.", ".tdata"),
4297   MAPPING_INIT(".gnu.linkonce.tb.", ".tbss"),
4298   MAPPING_INIT(".gnu.linkonce.lr.", ".lrodata"),
4299   MAPPING_INIT(".gnu.linkonce.l.", ".ldata"),
4300   MAPPING_INIT(".gnu.linkonce.lb.", ".lbss"),
4301   MAPPING_INIT(".ARM.extab", ".ARM.extab"),
4302   MAPPING_INIT(".gnu.linkonce.armextab.", ".ARM.extab"),
4303   MAPPING_INIT(".ARM.exidx", ".ARM.exidx"),
4304   MAPPING_INIT(".gnu.linkonce.armexidx.", ".ARM.exidx"),
4305 };
4306 #undef MAPPING_INIT
4307
4308 const int Layout::section_name_mapping_count =
4309   (sizeof(Layout::section_name_mapping)
4310    / sizeof(Layout::section_name_mapping[0]));
4311
4312 // Choose the output section name to use given an input section name.
4313 // Set *PLEN to the length of the name.  *PLEN is initialized to the
4314 // length of NAME.
4315
4316 const char*
4317 Layout::output_section_name(const Relobj* relobj, const char* name,
4318                             size_t* plen)
4319 {
4320   // gcc 4.3 generates the following sorts of section names when it
4321   // needs a section name specific to a function:
4322   //   .text.FN
4323   //   .rodata.FN
4324   //   .sdata2.FN
4325   //   .data.FN
4326   //   .data.rel.FN
4327   //   .data.rel.local.FN
4328   //   .data.rel.ro.FN
4329   //   .data.rel.ro.local.FN
4330   //   .sdata.FN
4331   //   .bss.FN
4332   //   .sbss.FN
4333   //   .tdata.FN
4334   //   .tbss.FN
4335
4336   // The GNU linker maps all of those to the part before the .FN,
4337   // except that .data.rel.local.FN is mapped to .data, and
4338   // .data.rel.ro.local.FN is mapped to .data.rel.ro.  The sections
4339   // beginning with .data.rel.ro.local are grouped together.
4340
4341   // For an anonymous namespace, the string FN can contain a '.'.
4342
4343   // Also of interest: .rodata.strN.N, .rodata.cstN, both of which the
4344   // GNU linker maps to .rodata.
4345
4346   // The .data.rel.ro sections are used with -z relro.  The sections
4347   // are recognized by name.  We use the same names that the GNU
4348   // linker does for these sections.
4349
4350   // It is hard to handle this in a principled way, so we don't even
4351   // try.  We use a table of mappings.  If the input section name is
4352   // not found in the table, we simply use it as the output section
4353   // name.
4354
4355   const Section_name_mapping* psnm = section_name_mapping;
4356   for (int i = 0; i < section_name_mapping_count; ++i, ++psnm)
4357     {
4358       if (strncmp(name, psnm->from, psnm->fromlen) == 0)
4359         {
4360           *plen = psnm->tolen;
4361           return psnm->to;
4362         }
4363     }
4364
4365   // As an additional complication, .ctors sections are output in
4366   // either .ctors or .init_array sections, and .dtors sections are
4367   // output in either .dtors or .fini_array sections.
4368   if (is_prefix_of(".ctors.", name) || is_prefix_of(".dtors.", name))
4369     {
4370       if (parameters->options().ctors_in_init_array())
4371         {
4372           *plen = 11;
4373           return name[1] == 'c' ? ".init_array" : ".fini_array";
4374         }
4375       else
4376         {
4377           *plen = 6;
4378           return name[1] == 'c' ? ".ctors" : ".dtors";
4379         }
4380     }
4381   if (parameters->options().ctors_in_init_array()
4382       && (strcmp(name, ".ctors") == 0 || strcmp(name, ".dtors") == 0))
4383     {
4384       // To make .init_array/.fini_array work with gcc we must exclude
4385       // .ctors and .dtors sections from the crtbegin and crtend
4386       // files.
4387       if (relobj == NULL
4388           || (!Layout::match_file_name(relobj, "crtbegin")
4389               && !Layout::match_file_name(relobj, "crtend")))
4390         {
4391           *plen = 11;
4392           return name[1] == 'c' ? ".init_array" : ".fini_array";
4393         }
4394     }
4395
4396   return name;
4397 }
4398
4399 // Return true if RELOBJ is an input file whose base name matches
4400 // FILE_NAME.  The base name must have an extension of ".o", and must
4401 // be exactly FILE_NAME.o or FILE_NAME, one character, ".o".  This is
4402 // to match crtbegin.o as well as crtbeginS.o without getting confused
4403 // by other possibilities.  Overall matching the file name this way is
4404 // a dreadful hack, but the GNU linker does it in order to better
4405 // support gcc, and we need to be compatible.
4406
4407 bool
4408 Layout::match_file_name(const Relobj* relobj, const char* match)
4409 {
4410   const std::string& file_name(relobj->name());
4411   const char* base_name = lbasename(file_name.c_str());
4412   size_t match_len = strlen(match);
4413   if (strncmp(base_name, match, match_len) != 0)
4414     return false;
4415   size_t base_len = strlen(base_name);
4416   if (base_len != match_len + 2 && base_len != match_len + 3)
4417     return false;
4418   return memcmp(base_name + base_len - 2, ".o", 2) == 0;
4419 }
4420
4421 // Check if a comdat group or .gnu.linkonce section with the given
4422 // NAME is selected for the link.  If there is already a section,
4423 // *KEPT_SECTION is set to point to the existing section and the
4424 // function returns false.  Otherwise, OBJECT, SHNDX, IS_COMDAT, and
4425 // IS_GROUP_NAME are recorded for this NAME in the layout object,
4426 // *KEPT_SECTION is set to the internal copy and the function returns
4427 // true.
4428
4429 bool
4430 Layout::find_or_add_kept_section(const std::string& name,
4431                                  Relobj* object,
4432                                  unsigned int shndx,
4433                                  bool is_comdat,
4434                                  bool is_group_name,
4435                                  Kept_section** kept_section)
4436 {
4437   // It's normal to see a couple of entries here, for the x86 thunk
4438   // sections.  If we see more than a few, we're linking a C++
4439   // program, and we resize to get more space to minimize rehashing.
4440   if (this->signatures_.size() > 4
4441       && !this->resized_signatures_)
4442     {
4443       reserve_unordered_map(&this->signatures_,
4444                             this->number_of_input_files_ * 64);
4445       this->resized_signatures_ = true;
4446     }
4447
4448   Kept_section candidate;
4449   std::pair<Signatures::iterator, bool> ins =
4450     this->signatures_.insert(std::make_pair(name, candidate));
4451
4452   if (kept_section != NULL)
4453     *kept_section = &ins.first->second;
4454   if (ins.second)
4455     {
4456       // This is the first time we've seen this signature.
4457       ins.first->second.set_object(object);
4458       ins.first->second.set_shndx(shndx);
4459       if (is_comdat)
4460         ins.first->second.set_is_comdat();
4461       if (is_group_name)
4462         ins.first->second.set_is_group_name();
4463       return true;
4464     }
4465
4466   // We have already seen this signature.
4467
4468   if (ins.first->second.is_group_name())
4469     {
4470       // We've already seen a real section group with this signature.
4471       // If the kept group is from a plugin object, and we're in the
4472       // replacement phase, accept the new one as a replacement.
4473       if (ins.first->second.object() == NULL
4474           && parameters->options().plugins()->in_replacement_phase())
4475         {
4476           ins.first->second.set_object(object);
4477           ins.first->second.set_shndx(shndx);
4478           return true;
4479         }
4480       return false;
4481     }
4482   else if (is_group_name)
4483     {
4484       // This is a real section group, and we've already seen a
4485       // linkonce section with this signature.  Record that we've seen
4486       // a section group, and don't include this section group.
4487       ins.first->second.set_is_group_name();
4488       return false;
4489     }
4490   else
4491     {
4492       // We've already seen a linkonce section and this is a linkonce
4493       // section.  These don't block each other--this may be the same
4494       // symbol name with different section types.
4495       return true;
4496     }
4497 }
4498
4499 // Store the allocated sections into the section list.
4500
4501 void
4502 Layout::get_allocated_sections(Section_list* section_list) const
4503 {
4504   for (Section_list::const_iterator p = this->section_list_.begin();
4505        p != this->section_list_.end();
4506        ++p)
4507     if (((*p)->flags() & elfcpp::SHF_ALLOC) != 0)
4508       section_list->push_back(*p);
4509 }
4510
4511 // Create an output segment.
4512
4513 Output_segment*
4514 Layout::make_output_segment(elfcpp::Elf_Word type, elfcpp::Elf_Word flags)
4515 {
4516   gold_assert(!parameters->options().relocatable());
4517   Output_segment* oseg = new Output_segment(type, flags);
4518   this->segment_list_.push_back(oseg);
4519
4520   if (type == elfcpp::PT_TLS)
4521     this->tls_segment_ = oseg;
4522   else if (type == elfcpp::PT_GNU_RELRO)
4523     this->relro_segment_ = oseg;
4524   else if (type == elfcpp::PT_INTERP)
4525     this->interp_segment_ = oseg;
4526
4527   return oseg;
4528 }
4529
4530 // Return the file offset of the normal symbol table.
4531
4532 off_t
4533 Layout::symtab_section_offset() const
4534 {
4535   if (this->symtab_section_ != NULL)
4536     return this->symtab_section_->offset();
4537   return 0;
4538 }
4539
4540 // Return the section index of the normal symbol table.  It may have
4541 // been stripped by the -s/--strip-all option.
4542
4543 unsigned int
4544 Layout::symtab_section_shndx() const
4545 {
4546   if (this->symtab_section_ != NULL)
4547     return this->symtab_section_->out_shndx();
4548   return 0;
4549 }
4550
4551 // Write out the Output_sections.  Most won't have anything to write,
4552 // since most of the data will come from input sections which are
4553 // handled elsewhere.  But some Output_sections do have Output_data.
4554
4555 void
4556 Layout::write_output_sections(Output_file* of) const
4557 {
4558   for (Section_list::const_iterator p = this->section_list_.begin();
4559        p != this->section_list_.end();
4560        ++p)
4561     {
4562       if (!(*p)->after_input_sections())
4563         (*p)->write(of);
4564     }
4565 }
4566
4567 // Write out data not associated with a section or the symbol table.
4568
4569 void
4570 Layout::write_data(const Symbol_table* symtab, Output_file* of) const
4571 {
4572   if (!parameters->options().strip_all())
4573     {
4574       const Output_section* symtab_section = this->symtab_section_;
4575       for (Section_list::const_iterator p = this->section_list_.begin();
4576            p != this->section_list_.end();
4577            ++p)
4578         {
4579           if ((*p)->needs_symtab_index())
4580             {
4581               gold_assert(symtab_section != NULL);
4582               unsigned int index = (*p)->symtab_index();
4583               gold_assert(index > 0 && index != -1U);
4584               off_t off = (symtab_section->offset()
4585                            + index * symtab_section->entsize());
4586               symtab->write_section_symbol(*p, this->symtab_xindex_, of, off);
4587             }
4588         }
4589     }
4590
4591   const Output_section* dynsym_section = this->dynsym_section_;
4592   for (Section_list::const_iterator p = this->section_list_.begin();
4593        p != this->section_list_.end();
4594        ++p)
4595     {
4596       if ((*p)->needs_dynsym_index())
4597         {
4598           gold_assert(dynsym_section != NULL);
4599           unsigned int index = (*p)->dynsym_index();
4600           gold_assert(index > 0 && index != -1U);
4601           off_t off = (dynsym_section->offset()
4602                        + index * dynsym_section->entsize());
4603           symtab->write_section_symbol(*p, this->dynsym_xindex_, of, off);
4604         }
4605     }
4606
4607   // Write out the Output_data which are not in an Output_section.
4608   for (Data_list::const_iterator p = this->special_output_list_.begin();
4609        p != this->special_output_list_.end();
4610        ++p)
4611     (*p)->write(of);
4612 }
4613
4614 // Write out the Output_sections which can only be written after the
4615 // input sections are complete.
4616
4617 void
4618 Layout::write_sections_after_input_sections(Output_file* of)
4619 {
4620   // Determine the final section offsets, and thus the final output
4621   // file size.  Note we finalize the .shstrab last, to allow the
4622   // after_input_section sections to modify their section-names before
4623   // writing.
4624   if (this->any_postprocessing_sections_)
4625     {
4626       off_t off = this->output_file_size_;
4627       off = this->set_section_offsets(off, POSTPROCESSING_SECTIONS_PASS);
4628
4629       // Now that we've finalized the names, we can finalize the shstrab.
4630       off =
4631         this->set_section_offsets(off,
4632                                   STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS);
4633
4634       if (off > this->output_file_size_)
4635         {
4636           of->resize(off);
4637           this->output_file_size_ = off;
4638         }
4639     }
4640
4641   for (Section_list::const_iterator p = this->section_list_.begin();
4642        p != this->section_list_.end();
4643        ++p)
4644     {
4645       if ((*p)->after_input_sections())
4646         (*p)->write(of);
4647     }
4648
4649   this->section_headers_->write(of);
4650 }
4651
4652 // If the build ID requires computing a checksum, do so here, and
4653 // write it out.  We compute a checksum over the entire file because
4654 // that is simplest.
4655
4656 void
4657 Layout::write_build_id(Output_file* of) const
4658 {
4659   if (this->build_id_note_ == NULL)
4660     return;
4661
4662   const unsigned char* iv = of->get_input_view(0, this->output_file_size_);
4663
4664   unsigned char* ov = of->get_output_view(this->build_id_note_->offset(),
4665                                           this->build_id_note_->data_size());
4666
4667   const char* style = parameters->options().build_id();
4668   if (strcmp(style, "sha1") == 0)
4669     {
4670       sha1_ctx ctx;
4671       sha1_init_ctx(&ctx);
4672       sha1_process_bytes(iv, this->output_file_size_, &ctx);
4673       sha1_finish_ctx(&ctx, ov);
4674     }
4675   else if (strcmp(style, "md5") == 0)
4676     {
4677       md5_ctx ctx;
4678       md5_init_ctx(&ctx);
4679       md5_process_bytes(iv, this->output_file_size_, &ctx);
4680       md5_finish_ctx(&ctx, ov);
4681     }
4682   else
4683     gold_unreachable();
4684
4685   of->write_output_view(this->build_id_note_->offset(),
4686                         this->build_id_note_->data_size(),
4687                         ov);
4688
4689   of->free_input_view(0, this->output_file_size_, iv);
4690 }
4691
4692 // Write out a binary file.  This is called after the link is
4693 // complete.  IN is the temporary output file we used to generate the
4694 // ELF code.  We simply walk through the segments, read them from
4695 // their file offset in IN, and write them to their load address in
4696 // the output file.  FIXME: with a bit more work, we could support
4697 // S-records and/or Intel hex format here.
4698
4699 void
4700 Layout::write_binary(Output_file* in) const
4701 {
4702   gold_assert(parameters->options().oformat_enum()
4703               == General_options::OBJECT_FORMAT_BINARY);
4704
4705   // Get the size of the binary file.
4706   uint64_t max_load_address = 0;
4707   for (Segment_list::const_iterator p = this->segment_list_.begin();
4708        p != this->segment_list_.end();
4709        ++p)
4710     {
4711       if ((*p)->type() == elfcpp::PT_LOAD && (*p)->filesz() > 0)
4712         {
4713           uint64_t max_paddr = (*p)->paddr() + (*p)->filesz();
4714           if (max_paddr > max_load_address)
4715             max_load_address = max_paddr;
4716         }
4717     }
4718
4719   Output_file out(parameters->options().output_file_name());
4720   out.open(max_load_address);
4721
4722   for (Segment_list::const_iterator p = this->segment_list_.begin();
4723        p != this->segment_list_.end();
4724        ++p)
4725     {
4726       if ((*p)->type() == elfcpp::PT_LOAD && (*p)->filesz() > 0)
4727         {
4728           const unsigned char* vin = in->get_input_view((*p)->offset(),
4729                                                         (*p)->filesz());
4730           unsigned char* vout = out.get_output_view((*p)->paddr(),
4731                                                     (*p)->filesz());
4732           memcpy(vout, vin, (*p)->filesz());
4733           out.write_output_view((*p)->paddr(), (*p)->filesz(), vout);
4734           in->free_input_view((*p)->offset(), (*p)->filesz(), vin);
4735         }
4736     }
4737
4738   out.close();
4739 }
4740
4741 // Print the output sections to the map file.
4742
4743 void
4744 Layout::print_to_mapfile(Mapfile* mapfile) const
4745 {
4746   for (Segment_list::const_iterator p = this->segment_list_.begin();
4747        p != this->segment_list_.end();
4748        ++p)
4749     (*p)->print_sections_to_mapfile(mapfile);
4750 }
4751
4752 // Print statistical information to stderr.  This is used for --stats.
4753
4754 void
4755 Layout::print_stats() const
4756 {
4757   this->namepool_.print_stats("section name pool");
4758   this->sympool_.print_stats("output symbol name pool");
4759   this->dynpool_.print_stats("dynamic name pool");
4760
4761   for (Section_list::const_iterator p = this->section_list_.begin();
4762        p != this->section_list_.end();
4763        ++p)
4764     (*p)->print_merge_stats();
4765 }
4766
4767 // Write_sections_task methods.
4768
4769 // We can always run this task.
4770
4771 Task_token*
4772 Write_sections_task::is_runnable()
4773 {
4774   return NULL;
4775 }
4776
4777 // We need to unlock both OUTPUT_SECTIONS_BLOCKER and FINAL_BLOCKER
4778 // when finished.
4779
4780 void
4781 Write_sections_task::locks(Task_locker* tl)
4782 {
4783   tl->add(this, this->output_sections_blocker_);
4784   tl->add(this, this->final_blocker_);
4785 }
4786
4787 // Run the task--write out the data.
4788
4789 void
4790 Write_sections_task::run(Workqueue*)
4791 {
4792   this->layout_->write_output_sections(this->of_);
4793 }
4794
4795 // Write_data_task methods.
4796
4797 // We can always run this task.
4798
4799 Task_token*
4800 Write_data_task::is_runnable()
4801 {
4802   return NULL;
4803 }
4804
4805 // We need to unlock FINAL_BLOCKER when finished.
4806
4807 void
4808 Write_data_task::locks(Task_locker* tl)
4809 {
4810   tl->add(this, this->final_blocker_);
4811 }
4812
4813 // Run the task--write out the data.
4814
4815 void
4816 Write_data_task::run(Workqueue*)
4817 {
4818   this->layout_->write_data(this->symtab_, this->of_);
4819 }
4820
4821 // Write_symbols_task methods.
4822
4823 // We can always run this task.
4824
4825 Task_token*
4826 Write_symbols_task::is_runnable()
4827 {
4828   return NULL;
4829 }
4830
4831 // We need to unlock FINAL_BLOCKER when finished.
4832
4833 void
4834 Write_symbols_task::locks(Task_locker* tl)
4835 {
4836   tl->add(this, this->final_blocker_);
4837 }
4838
4839 // Run the task--write out the symbols.
4840
4841 void
4842 Write_symbols_task::run(Workqueue*)
4843 {
4844   this->symtab_->write_globals(this->sympool_, this->dynpool_,
4845                                this->layout_->symtab_xindex(),
4846                                this->layout_->dynsym_xindex(), this->of_);
4847 }
4848
4849 // Write_after_input_sections_task methods.
4850
4851 // We can only run this task after the input sections have completed.
4852
4853 Task_token*
4854 Write_after_input_sections_task::is_runnable()
4855 {
4856   if (this->input_sections_blocker_->is_blocked())
4857     return this->input_sections_blocker_;
4858   return NULL;
4859 }
4860
4861 // We need to unlock FINAL_BLOCKER when finished.
4862
4863 void
4864 Write_after_input_sections_task::locks(Task_locker* tl)
4865 {
4866   tl->add(this, this->final_blocker_);
4867 }
4868
4869 // Run the task.
4870
4871 void
4872 Write_after_input_sections_task::run(Workqueue*)
4873 {
4874   this->layout_->write_sections_after_input_sections(this->of_);
4875 }
4876
4877 // Close_task_runner methods.
4878
4879 // Run the task--close the file.
4880
4881 void
4882 Close_task_runner::run(Workqueue*, const Task*)
4883 {
4884   // If we need to compute a checksum for the BUILD if, we do so here.
4885   this->layout_->write_build_id(this->of_);
4886
4887   // If we've been asked to create a binary file, we do so here.
4888   if (this->options_->oformat_enum() != General_options::OBJECT_FORMAT_ELF)
4889     this->layout_->write_binary(this->of_);
4890
4891   this->of_->close();
4892 }
4893
4894 // Instantiate the templates we need.  We could use the configure
4895 // script to restrict this to only the ones for implemented targets.
4896
4897 #ifdef HAVE_TARGET_32_LITTLE
4898 template
4899 Output_section*
4900 Layout::init_fixed_output_section<32, false>(
4901     const char* name,
4902     elfcpp::Shdr<32, false>& shdr);
4903 #endif
4904
4905 #ifdef HAVE_TARGET_32_BIG
4906 template
4907 Output_section*
4908 Layout::init_fixed_output_section<32, true>(
4909     const char* name,
4910     elfcpp::Shdr<32, true>& shdr);
4911 #endif
4912
4913 #ifdef HAVE_TARGET_64_LITTLE
4914 template
4915 Output_section*
4916 Layout::init_fixed_output_section<64, false>(
4917     const char* name,
4918     elfcpp::Shdr<64, false>& shdr);
4919 #endif
4920
4921 #ifdef HAVE_TARGET_64_BIG
4922 template
4923 Output_section*
4924 Layout::init_fixed_output_section<64, true>(
4925     const char* name,
4926     elfcpp::Shdr<64, true>& shdr);
4927 #endif
4928
4929 #ifdef HAVE_TARGET_32_LITTLE
4930 template
4931 Output_section*
4932 Layout::layout<32, false>(Sized_relobj_file<32, false>* object,
4933                           unsigned int shndx,
4934                           const char* name,
4935                           const elfcpp::Shdr<32, false>& shdr,
4936                           unsigned int, unsigned int, off_t*);
4937 #endif
4938
4939 #ifdef HAVE_TARGET_32_BIG
4940 template
4941 Output_section*
4942 Layout::layout<32, true>(Sized_relobj_file<32, true>* object,
4943                          unsigned int shndx,
4944                          const char* name,
4945                          const elfcpp::Shdr<32, true>& shdr,
4946                          unsigned int, unsigned int, off_t*);
4947 #endif
4948
4949 #ifdef HAVE_TARGET_64_LITTLE
4950 template
4951 Output_section*
4952 Layout::layout<64, false>(Sized_relobj_file<64, false>* object,
4953                           unsigned int shndx,
4954                           const char* name,
4955                           const elfcpp::Shdr<64, false>& shdr,
4956                           unsigned int, unsigned int, off_t*);
4957 #endif
4958
4959 #ifdef HAVE_TARGET_64_BIG
4960 template
4961 Output_section*
4962 Layout::layout<64, true>(Sized_relobj_file<64, true>* object,
4963                          unsigned int shndx,
4964                          const char* name,
4965                          const elfcpp::Shdr<64, true>& shdr,
4966                          unsigned int, unsigned int, off_t*);
4967 #endif
4968
4969 #ifdef HAVE_TARGET_32_LITTLE
4970 template
4971 Output_section*
4972 Layout::layout_reloc<32, false>(Sized_relobj_file<32, false>* object,
4973                                 unsigned int reloc_shndx,
4974                                 const elfcpp::Shdr<32, false>& shdr,
4975                                 Output_section* data_section,
4976                                 Relocatable_relocs* rr);
4977 #endif
4978
4979 #ifdef HAVE_TARGET_32_BIG
4980 template
4981 Output_section*
4982 Layout::layout_reloc<32, true>(Sized_relobj_file<32, true>* object,
4983                                unsigned int reloc_shndx,
4984                                const elfcpp::Shdr<32, true>& shdr,
4985                                Output_section* data_section,
4986                                Relocatable_relocs* rr);
4987 #endif
4988
4989 #ifdef HAVE_TARGET_64_LITTLE
4990 template
4991 Output_section*
4992 Layout::layout_reloc<64, false>(Sized_relobj_file<64, false>* object,
4993                                 unsigned int reloc_shndx,
4994                                 const elfcpp::Shdr<64, false>& shdr,
4995                                 Output_section* data_section,
4996                                 Relocatable_relocs* rr);
4997 #endif
4998
4999 #ifdef HAVE_TARGET_64_BIG
5000 template
5001 Output_section*
5002 Layout::layout_reloc<64, true>(Sized_relobj_file<64, true>* object,
5003                                unsigned int reloc_shndx,
5004                                const elfcpp::Shdr<64, true>& shdr,
5005                                Output_section* data_section,
5006                                Relocatable_relocs* rr);
5007 #endif
5008
5009 #ifdef HAVE_TARGET_32_LITTLE
5010 template
5011 void
5012 Layout::layout_group<32, false>(Symbol_table* symtab,
5013                                 Sized_relobj_file<32, false>* object,
5014                                 unsigned int,
5015                                 const char* group_section_name,
5016                                 const char* signature,
5017                                 const elfcpp::Shdr<32, false>& shdr,
5018                                 elfcpp::Elf_Word flags,
5019                                 std::vector<unsigned int>* shndxes);
5020 #endif
5021
5022 #ifdef HAVE_TARGET_32_BIG
5023 template
5024 void
5025 Layout::layout_group<32, true>(Symbol_table* symtab,
5026                                Sized_relobj_file<32, true>* object,
5027                                unsigned int,
5028                                const char* group_section_name,
5029                                const char* signature,
5030                                const elfcpp::Shdr<32, true>& shdr,
5031                                elfcpp::Elf_Word flags,
5032                                std::vector<unsigned int>* shndxes);
5033 #endif
5034
5035 #ifdef HAVE_TARGET_64_LITTLE
5036 template
5037 void
5038 Layout::layout_group<64, false>(Symbol_table* symtab,
5039                                 Sized_relobj_file<64, false>* object,
5040                                 unsigned int,
5041                                 const char* group_section_name,
5042                                 const char* signature,
5043                                 const elfcpp::Shdr<64, false>& shdr,
5044                                 elfcpp::Elf_Word flags,
5045                                 std::vector<unsigned int>* shndxes);
5046 #endif
5047
5048 #ifdef HAVE_TARGET_64_BIG
5049 template
5050 void
5051 Layout::layout_group<64, true>(Symbol_table* symtab,
5052                                Sized_relobj_file<64, true>* object,
5053                                unsigned int,
5054                                const char* group_section_name,
5055                                const char* signature,
5056                                const elfcpp::Shdr<64, true>& shdr,
5057                                elfcpp::Elf_Word flags,
5058                                std::vector<unsigned int>* shndxes);
5059 #endif
5060
5061 #ifdef HAVE_TARGET_32_LITTLE
5062 template
5063 Output_section*
5064 Layout::layout_eh_frame<32, false>(Sized_relobj_file<32, false>* object,
5065                                    const unsigned char* symbols,
5066                                    off_t symbols_size,
5067                                    const unsigned char* symbol_names,
5068                                    off_t symbol_names_size,
5069                                    unsigned int shndx,
5070                                    const elfcpp::Shdr<32, false>& shdr,
5071                                    unsigned int reloc_shndx,
5072                                    unsigned int reloc_type,
5073                                    off_t* off);
5074 #endif
5075
5076 #ifdef HAVE_TARGET_32_BIG
5077 template
5078 Output_section*
5079 Layout::layout_eh_frame<32, true>(Sized_relobj_file<32, true>* object,
5080                                   const unsigned char* symbols,
5081                                   off_t symbols_size,
5082                                   const unsigned char* symbol_names,
5083                                   off_t symbol_names_size,
5084                                   unsigned int shndx,
5085                                   const elfcpp::Shdr<32, true>& shdr,
5086                                   unsigned int reloc_shndx,
5087                                   unsigned int reloc_type,
5088                                   off_t* off);
5089 #endif
5090
5091 #ifdef HAVE_TARGET_64_LITTLE
5092 template
5093 Output_section*
5094 Layout::layout_eh_frame<64, false>(Sized_relobj_file<64, false>* object,
5095                                    const unsigned char* symbols,
5096                                    off_t symbols_size,
5097                                    const unsigned char* symbol_names,
5098                                    off_t symbol_names_size,
5099                                    unsigned int shndx,
5100                                    const elfcpp::Shdr<64, false>& shdr,
5101                                    unsigned int reloc_shndx,
5102                                    unsigned int reloc_type,
5103                                    off_t* off);
5104 #endif
5105
5106 #ifdef HAVE_TARGET_64_BIG
5107 template
5108 Output_section*
5109 Layout::layout_eh_frame<64, true>(Sized_relobj_file<64, true>* object,
5110                                   const unsigned char* symbols,
5111                                   off_t symbols_size,
5112                                   const unsigned char* symbol_names,
5113                                   off_t symbol_names_size,
5114                                   unsigned int shndx,
5115                                   const elfcpp::Shdr<64, true>& shdr,
5116                                   unsigned int reloc_shndx,
5117                                   unsigned int reloc_type,
5118                                   off_t* off);
5119 #endif
5120
5121 } // End namespace gold.