Merge branch 'vendor/GCC44'
[dragonfly.git] / contrib / binutils-2.21 / 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 "reloc.h"
50 #include "descriptors.h"
51 #include "plugin.h"
52 #include "incremental.h"
53 #include "layout.h"
54
55 namespace gold
56 {
57
58 // Layout::Relaxation_debug_check methods.
59
60 // Check that sections and special data are in reset states.
61 // We do not save states for Output_sections and special Output_data.
62 // So we check that they have not assigned any addresses or offsets.
63 // clean_up_after_relaxation simply resets their addresses and offsets.
64 void
65 Layout::Relaxation_debug_check::check_output_data_for_reset_values(
66     const Layout::Section_list& sections,
67     const Layout::Data_list& special_outputs)
68 {
69   for(Layout::Section_list::const_iterator p = sections.begin();
70       p != sections.end();
71       ++p)
72     gold_assert((*p)->address_and_file_offset_have_reset_values());
73
74   for(Layout::Data_list::const_iterator p = special_outputs.begin();
75       p != special_outputs.end();
76       ++p)
77     gold_assert((*p)->address_and_file_offset_have_reset_values());
78 }
79   
80 // Save information of SECTIONS for checking later.
81
82 void
83 Layout::Relaxation_debug_check::read_sections(
84     const Layout::Section_list& sections)
85 {
86   for(Layout::Section_list::const_iterator p = sections.begin();
87       p != sections.end();
88       ++p)
89     {
90       Output_section* os = *p;
91       Section_info info;
92       info.output_section = os;
93       info.address = os->is_address_valid() ? os->address() : 0;
94       info.data_size = os->is_data_size_valid() ? os->data_size() : -1;
95       info.offset = os->is_offset_valid()? os->offset() : -1 ;
96       this->section_infos_.push_back(info);
97     }
98 }
99
100 // Verify SECTIONS using previously recorded information.
101
102 void
103 Layout::Relaxation_debug_check::verify_sections(
104     const Layout::Section_list& sections)
105 {
106   size_t i = 0;
107   for(Layout::Section_list::const_iterator p = sections.begin();
108       p != sections.end();
109       ++p, ++i)
110     {
111       Output_section* os = *p;
112       uint64_t address = os->is_address_valid() ? os->address() : 0;
113       off_t data_size = os->is_data_size_valid() ? os->data_size() : -1;
114       off_t offset = os->is_offset_valid()? os->offset() : -1 ;
115
116       if (i >= this->section_infos_.size())
117         {
118           gold_fatal("Section_info of %s missing.\n", os->name());
119         }
120       const Section_info& info = this->section_infos_[i];
121       if (os != info.output_section)
122         gold_fatal("Section order changed.  Expecting %s but see %s\n",
123                    info.output_section->name(), os->name());
124       if (address != info.address
125           || data_size != info.data_size
126           || offset != info.offset)
127         gold_fatal("Section %s changed.\n", os->name());
128     }
129 }
130
131 // Layout_task_runner methods.
132
133 // Lay out the sections.  This is called after all the input objects
134 // have been read.
135
136 void
137 Layout_task_runner::run(Workqueue* workqueue, const Task* task)
138 {
139   off_t file_size = this->layout_->finalize(this->input_objects_,
140                                             this->symtab_,
141                                             this->target_,
142                                             task);
143
144   // Now we know the final size of the output file and we know where
145   // each piece of information goes.
146
147   if (this->mapfile_ != NULL)
148     {
149       this->mapfile_->print_discarded_sections(this->input_objects_);
150       this->layout_->print_to_mapfile(this->mapfile_);
151     }
152
153   Output_file* of = new Output_file(parameters->options().output_file_name());
154   if (this->options_.oformat_enum() != General_options::OBJECT_FORMAT_ELF)
155     of->set_is_temporary();
156   of->open(file_size);
157
158   // Queue up the final set of tasks.
159   gold::queue_final_tasks(this->options_, this->input_objects_,
160                           this->symtab_, this->layout_, workqueue, of);
161 }
162
163 // Layout methods.
164
165 Layout::Layout(int number_of_input_files, Script_options* script_options)
166   : number_of_input_files_(number_of_input_files),
167     script_options_(script_options),
168     namepool_(),
169     sympool_(),
170     dynpool_(),
171     signatures_(),
172     section_name_map_(),
173     segment_list_(),
174     section_list_(),
175     unattached_section_list_(),
176     special_output_list_(),
177     section_headers_(NULL),
178     tls_segment_(NULL),
179     relro_segment_(NULL),
180     increase_relro_(0),
181     symtab_section_(NULL),
182     symtab_xindex_(NULL),
183     dynsym_section_(NULL),
184     dynsym_xindex_(NULL),
185     dynamic_section_(NULL),
186     dynamic_symbol_(NULL),
187     dynamic_data_(NULL),
188     eh_frame_section_(NULL),
189     eh_frame_data_(NULL),
190     added_eh_frame_data_(false),
191     eh_frame_hdr_section_(NULL),
192     build_id_note_(NULL),
193     debug_abbrev_(NULL),
194     debug_info_(NULL),
195     group_signatures_(),
196     output_file_size_(-1),
197     have_added_input_section_(false),
198     sections_are_attached_(false),
199     input_requires_executable_stack_(false),
200     input_with_gnu_stack_note_(false),
201     input_without_gnu_stack_note_(false),
202     has_static_tls_(false),
203     any_postprocessing_sections_(false),
204     resized_signatures_(false),
205     have_stabstr_section_(false),
206     incremental_inputs_(NULL),
207     record_output_section_data_from_script_(false),
208     script_output_section_data_list_(),
209     segment_states_(NULL),
210     relaxation_debug_check_(NULL)
211 {
212   // Make space for more than enough segments for a typical file.
213   // This is just for efficiency--it's OK if we wind up needing more.
214   this->segment_list_.reserve(12);
215
216   // We expect two unattached Output_data objects: the file header and
217   // the segment headers.
218   this->special_output_list_.reserve(2);
219
220   // Initialize structure needed for an incremental build.
221   if (parameters->incremental())
222     this->incremental_inputs_ = new Incremental_inputs;
223
224   // The section name pool is worth optimizing in all cases, because
225   // it is small, but there are often overlaps due to .rel sections.
226   this->namepool_.set_optimize();
227 }
228
229 // Hash a key we use to look up an output section mapping.
230
231 size_t
232 Layout::Hash_key::operator()(const Layout::Key& k) const
233 {
234  return k.first + k.second.first + k.second.second;
235 }
236
237 // Returns whether the given section is in the list of
238 // debug-sections-used-by-some-version-of-gdb.  Currently,
239 // we've checked versions of gdb up to and including 6.7.1.
240
241 static const char* gdb_sections[] =
242 { ".debug_abbrev",
243   // ".debug_aranges",   // not used by gdb as of 6.7.1
244   ".debug_frame",
245   ".debug_info",
246   ".debug_types",
247   ".debug_line",
248   ".debug_loc",
249   ".debug_macinfo",
250   // ".debug_pubnames",  // not used by gdb as of 6.7.1
251   ".debug_ranges",
252   ".debug_str",
253 };
254
255 static const char* lines_only_debug_sections[] =
256 { ".debug_abbrev",
257   // ".debug_aranges",   // not used by gdb as of 6.7.1
258   // ".debug_frame",
259   ".debug_info",
260   // ".debug_types",
261   ".debug_line",
262   // ".debug_loc",
263   // ".debug_macinfo",
264   // ".debug_pubnames",  // not used by gdb as of 6.7.1
265   // ".debug_ranges",
266   ".debug_str",
267 };
268
269 static inline bool
270 is_gdb_debug_section(const char* str)
271 {
272   // We can do this faster: binary search or a hashtable.  But why bother?
273   for (size_t i = 0; i < sizeof(gdb_sections)/sizeof(*gdb_sections); ++i)
274     if (strcmp(str, gdb_sections[i]) == 0)
275       return true;
276   return false;
277 }
278
279 static inline bool
280 is_lines_only_debug_section(const char* str)
281 {
282   // We can do this faster: binary search or a hashtable.  But why bother?
283   for (size_t i = 0;
284        i < sizeof(lines_only_debug_sections)/sizeof(*lines_only_debug_sections);
285        ++i)
286     if (strcmp(str, lines_only_debug_sections[i]) == 0)
287       return true;
288   return false;
289 }
290
291 // Whether to include this section in the link.
292
293 template<int size, bool big_endian>
294 bool
295 Layout::include_section(Sized_relobj<size, big_endian>*, const char* name,
296                         const elfcpp::Shdr<size, big_endian>& shdr)
297 {
298   if (shdr.get_sh_flags() & elfcpp::SHF_EXCLUDE)
299     return false;
300
301   switch (shdr.get_sh_type())
302     {
303     case elfcpp::SHT_NULL:
304     case elfcpp::SHT_SYMTAB:
305     case elfcpp::SHT_DYNSYM:
306     case elfcpp::SHT_HASH:
307     case elfcpp::SHT_DYNAMIC:
308     case elfcpp::SHT_SYMTAB_SHNDX:
309       return false;
310
311     case elfcpp::SHT_STRTAB:
312       // Discard the sections which have special meanings in the ELF
313       // ABI.  Keep others (e.g., .stabstr).  We could also do this by
314       // checking the sh_link fields of the appropriate sections.
315       return (strcmp(name, ".dynstr") != 0
316               && strcmp(name, ".strtab") != 0
317               && strcmp(name, ".shstrtab") != 0);
318
319     case elfcpp::SHT_RELA:
320     case elfcpp::SHT_REL:
321     case elfcpp::SHT_GROUP:
322       // If we are emitting relocations these should be handled
323       // elsewhere.
324       gold_assert(!parameters->options().relocatable()
325                   && !parameters->options().emit_relocs());
326       return false;
327
328     case elfcpp::SHT_PROGBITS:
329       if (parameters->options().strip_debug()
330           && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
331         {
332           if (is_debug_info_section(name))
333             return false;
334         }
335       if (parameters->options().strip_debug_non_line()
336           && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
337         {
338           // Debugging sections can only be recognized by name.
339           if (is_prefix_of(".debug", name)
340               && !is_lines_only_debug_section(name))
341             return false;
342         }
343       if (parameters->options().strip_debug_gdb()
344           && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
345         {
346           // Debugging sections can only be recognized by name.
347           if (is_prefix_of(".debug", name)
348               && !is_gdb_debug_section(name))
349             return false;
350         }
351       if (parameters->options().strip_lto_sections()
352           && !parameters->options().relocatable()
353           && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
354         {
355           // Ignore LTO sections containing intermediate code.
356           if (is_prefix_of(".gnu.lto_", name))
357             return false;
358         }
359       // The GNU linker strips .gnu_debuglink sections, so we do too.
360       // This is a feature used to keep debugging information in
361       // separate files.
362       if (strcmp(name, ".gnu_debuglink") == 0)
363         return false;
364       return true;
365
366     default:
367       return true;
368     }
369 }
370
371 // Return an output section named NAME, or NULL if there is none.
372
373 Output_section*
374 Layout::find_output_section(const char* name) const
375 {
376   for (Section_list::const_iterator p = this->section_list_.begin();
377        p != this->section_list_.end();
378        ++p)
379     if (strcmp((*p)->name(), name) == 0)
380       return *p;
381   return NULL;
382 }
383
384 // Return an output segment of type TYPE, with segment flags SET set
385 // and segment flags CLEAR clear.  Return NULL if there is none.
386
387 Output_segment*
388 Layout::find_output_segment(elfcpp::PT type, elfcpp::Elf_Word set,
389                             elfcpp::Elf_Word clear) const
390 {
391   for (Segment_list::const_iterator p = this->segment_list_.begin();
392        p != this->segment_list_.end();
393        ++p)
394     if (static_cast<elfcpp::PT>((*p)->type()) == type
395         && ((*p)->flags() & set) == set
396         && ((*p)->flags() & clear) == 0)
397       return *p;
398   return NULL;
399 }
400
401 // Return the output section to use for section NAME with type TYPE
402 // and section flags FLAGS.  NAME must be canonicalized in the string
403 // pool, and NAME_KEY is the key.  IS_INTERP is true if this is the
404 // .interp section.  IS_DYNAMIC_LINKER_SECTION is true if this section
405 // is used by the dynamic linker.  IS_RELRO is true for a relro
406 // section.  IS_LAST_RELRO is true for the last relro section.
407 // IS_FIRST_NON_RELRO is true for the first non-relro section.
408
409 Output_section*
410 Layout::get_output_section(const char* name, Stringpool::Key name_key,
411                            elfcpp::Elf_Word type, elfcpp::Elf_Xword flags,
412                            Output_section_order order, bool is_relro)
413 {
414   elfcpp::Elf_Xword lookup_flags = flags;
415
416   // Ignoring SHF_WRITE and SHF_EXECINSTR here means that we combine
417   // read-write with read-only sections.  Some other ELF linkers do
418   // not do this.  FIXME: Perhaps there should be an option
419   // controlling this.
420   lookup_flags &= ~(elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR);
421
422   const Key key(name_key, std::make_pair(type, lookup_flags));
423   const std::pair<Key, Output_section*> v(key, NULL);
424   std::pair<Section_name_map::iterator, bool> ins(
425     this->section_name_map_.insert(v));
426
427   if (!ins.second)
428     return ins.first->second;
429   else
430     {
431       // This is the first time we've seen this name/type/flags
432       // combination.  For compatibility with the GNU linker, we
433       // combine sections with contents and zero flags with sections
434       // with non-zero flags.  This is a workaround for cases where
435       // assembler code forgets to set section flags.  FIXME: Perhaps
436       // there should be an option to control this.
437       Output_section* os = NULL;
438
439       if (type == elfcpp::SHT_PROGBITS)
440         {
441           if (flags == 0)
442             {
443               Output_section* same_name = this->find_output_section(name);
444               if (same_name != NULL
445                   && same_name->type() == elfcpp::SHT_PROGBITS
446                   && (same_name->flags() & elfcpp::SHF_TLS) == 0)
447                 os = same_name;
448             }
449           else if ((flags & elfcpp::SHF_TLS) == 0)
450             {
451               elfcpp::Elf_Xword zero_flags = 0;
452               const Key zero_key(name_key, std::make_pair(type, zero_flags));
453               Section_name_map::iterator p =
454                   this->section_name_map_.find(zero_key);
455               if (p != this->section_name_map_.end())
456                 os = p->second;
457             }
458         }
459
460       if (os == NULL)
461         os = this->make_output_section(name, type, flags, order, is_relro);
462
463       ins.first->second = os;
464       return os;
465     }
466 }
467
468 // Pick the output section to use for section NAME, in input file
469 // RELOBJ, with type TYPE and flags FLAGS.  RELOBJ may be NULL for a
470 // linker created section.  IS_INPUT_SECTION is true if we are
471 // choosing an output section for an input section found in a input
472 // file.  IS_INTERP is true if this is the .interp section.
473 // IS_DYNAMIC_LINKER_SECTION is true if this section is used by the
474 // dynamic linker.  IS_RELRO is true for a relro section.
475 // IS_LAST_RELRO is true for the last relro section.
476 // IS_FIRST_NON_RELRO is true for the first non-relro section.  This
477 // will return NULL if the input section should be discarded.
478
479 Output_section*
480 Layout::choose_output_section(const Relobj* relobj, const char* name,
481                               elfcpp::Elf_Word type, elfcpp::Elf_Xword flags,
482                               bool is_input_section, Output_section_order order,
483                               bool is_relro)
484 {
485   // We should not see any input sections after we have attached
486   // sections to segments.
487   gold_assert(!is_input_section || !this->sections_are_attached_);
488
489   // Some flags in the input section should not be automatically
490   // copied to the output section.
491   flags &= ~ (elfcpp::SHF_INFO_LINK
492               | elfcpp::SHF_GROUP
493               | elfcpp::SHF_MERGE
494               | elfcpp::SHF_STRINGS);
495
496   // We only clear the SHF_LINK_ORDER flag in for
497   // a non-relocatable link.
498   if (!parameters->options().relocatable())
499     flags &= ~elfcpp::SHF_LINK_ORDER;
500
501   if (this->script_options_->saw_sections_clause())
502     {
503       // We are using a SECTIONS clause, so the output section is
504       // chosen based only on the name.
505
506       Script_sections* ss = this->script_options_->script_sections();
507       const char* file_name = relobj == NULL ? NULL : relobj->name().c_str();
508       Output_section** output_section_slot;
509       Script_sections::Section_type script_section_type;
510       const char* orig_name = name;
511       name = ss->output_section_name(file_name, name, &output_section_slot,
512                                      &script_section_type);
513       if (name == NULL)
514         {
515           gold_debug(DEBUG_SCRIPT, _("Unable to create output section '%s' "
516                                      "because it is not allowed by the "
517                                      "SECTIONS clause of the linker script"),
518                      orig_name);
519           // The SECTIONS clause says to discard this input section.
520           return NULL;
521         }
522
523       // We can only handle script section types ST_NONE and ST_NOLOAD.
524       switch (script_section_type)
525         {
526         case Script_sections::ST_NONE:
527           break;
528         case Script_sections::ST_NOLOAD:
529           flags &= elfcpp::SHF_ALLOC;
530           break;
531         default:
532           gold_unreachable();
533         }
534
535       // If this is an orphan section--one not mentioned in the linker
536       // script--then OUTPUT_SECTION_SLOT will be NULL, and we do the
537       // default processing below.
538
539       if (output_section_slot != NULL)
540         {
541           if (*output_section_slot != NULL)
542             {
543               (*output_section_slot)->update_flags_for_input_section(flags);
544               return *output_section_slot;
545             }
546
547           // We don't put sections found in the linker script into
548           // SECTION_NAME_MAP_.  That keeps us from getting confused
549           // if an orphan section is mapped to a section with the same
550           // name as one in the linker script.
551
552           name = this->namepool_.add(name, false, NULL);
553
554           Output_section* os = this->make_output_section(name, type, flags,
555                                                          order, is_relro);
556
557           os->set_found_in_sections_clause();
558
559           // Special handling for NOLOAD sections.
560           if (script_section_type == Script_sections::ST_NOLOAD)
561             {
562               os->set_is_noload();
563
564               // The constructor of Output_section sets addresses of non-ALLOC
565               // sections to 0 by default.  We don't want that for NOLOAD
566               // sections even if they have no SHF_ALLOC flag.
567               if ((os->flags() & elfcpp::SHF_ALLOC) == 0
568                   && os->is_address_valid())
569                 {
570                   gold_assert(os->address() == 0
571                               && !os->is_offset_valid()
572                               && !os->is_data_size_valid());
573                   os->reset_address_and_file_offset();
574                 }
575             }
576
577           *output_section_slot = os;
578           return os;
579         }
580     }
581
582   // FIXME: Handle SHF_OS_NONCONFORMING somewhere.
583
584   // Turn NAME from the name of the input section into the name of the
585   // output section.
586
587   size_t len = strlen(name);
588   if (is_input_section
589       && !this->script_options_->saw_sections_clause()
590       && !parameters->options().relocatable())
591     name = Layout::output_section_name(name, &len);
592
593   Stringpool::Key name_key;
594   name = this->namepool_.add_with_length(name, len, true, &name_key);
595
596   // Find or make the output section.  The output section is selected
597   // based on the section name, type, and flags.
598   return this->get_output_section(name, name_key, type, flags, order, is_relro);
599 }
600
601 // Return the output section to use for input section SHNDX, with name
602 // NAME, with header HEADER, from object OBJECT.  RELOC_SHNDX is the
603 // index of a relocation section which applies to this section, or 0
604 // if none, or -1U if more than one.  RELOC_TYPE is the type of the
605 // relocation section if there is one.  Set *OFF to the offset of this
606 // input section without the output section.  Return NULL if the
607 // section should be discarded.  Set *OFF to -1 if the section
608 // contents should not be written directly to the output file, but
609 // will instead receive special handling.
610
611 template<int size, bool big_endian>
612 Output_section*
613 Layout::layout(Sized_relobj<size, big_endian>* object, unsigned int shndx,
614                const char* name, const elfcpp::Shdr<size, big_endian>& shdr,
615                unsigned int reloc_shndx, unsigned int, off_t* off)
616 {
617   *off = 0;
618
619   if (!this->include_section(object, name, shdr))
620     return NULL;
621
622   Output_section* os;
623
624   // Sometimes .init_array*, .preinit_array* and .fini_array* do not have
625   // correct section types.  Force them here.
626   elfcpp::Elf_Word sh_type = shdr.get_sh_type();
627   if (sh_type == elfcpp::SHT_PROGBITS)
628     {
629       static const char init_array_prefix[] = ".init_array";
630       static const char preinit_array_prefix[] = ".preinit_array";
631       static const char fini_array_prefix[] = ".fini_array";
632       static size_t init_array_prefix_size = sizeof(init_array_prefix) - 1;
633       static size_t preinit_array_prefix_size =
634         sizeof(preinit_array_prefix) - 1;
635       static size_t fini_array_prefix_size = sizeof(fini_array_prefix) - 1;
636
637       if (strncmp(name, init_array_prefix, init_array_prefix_size) == 0)
638         sh_type = elfcpp::SHT_INIT_ARRAY;
639       else if (strncmp(name, preinit_array_prefix, preinit_array_prefix_size)
640                == 0)
641         sh_type = elfcpp::SHT_PREINIT_ARRAY;
642       else if (strncmp(name, fini_array_prefix, fini_array_prefix_size) == 0)
643         sh_type = elfcpp::SHT_FINI_ARRAY;
644     }
645
646   // In a relocatable link a grouped section must not be combined with
647   // any other sections.
648   if (parameters->options().relocatable()
649       && (shdr.get_sh_flags() & elfcpp::SHF_GROUP) != 0)
650     {
651       name = this->namepool_.add(name, true, NULL);
652       os = this->make_output_section(name, sh_type, shdr.get_sh_flags(),
653                                      ORDER_INVALID, false);
654     }
655   else
656     {
657       os = this->choose_output_section(object, name, sh_type,
658                                        shdr.get_sh_flags(), true,
659                                        ORDER_INVALID, false);
660       if (os == NULL)
661         return NULL;
662     }
663
664   // By default the GNU linker sorts input sections whose names match
665   // .ctor.*, .dtor.*, .init_array.*, or .fini_array.*.  The sections
666   // are sorted by name.  This is used to implement constructor
667   // priority ordering.  We are compatible.
668   if (!this->script_options_->saw_sections_clause()
669       && (is_prefix_of(".ctors.", name)
670           || is_prefix_of(".dtors.", name)
671           || is_prefix_of(".init_array.", name)
672           || is_prefix_of(".fini_array.", name)))
673     os->set_must_sort_attached_input_sections();
674
675   // FIXME: Handle SHF_LINK_ORDER somewhere.
676
677   elfcpp::Elf_Xword orig_flags = os->flags();
678
679   *off = os->add_input_section(this, object, shndx, name, shdr, reloc_shndx,
680                                this->script_options_->saw_sections_clause());
681
682   // If the flags changed, we may have to change the order.
683   if ((orig_flags & elfcpp::SHF_ALLOC) != 0)
684     {
685       orig_flags &= (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR);
686       elfcpp::Elf_Xword new_flags =
687         os->flags() & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR);
688       if (orig_flags != new_flags)
689         os->set_order(this->default_section_order(os, false));
690     }
691
692   this->have_added_input_section_ = true;
693
694   return os;
695 }
696
697 // Handle a relocation section when doing a relocatable link.
698
699 template<int size, bool big_endian>
700 Output_section*
701 Layout::layout_reloc(Sized_relobj<size, big_endian>* object,
702                      unsigned int,
703                      const elfcpp::Shdr<size, big_endian>& shdr,
704                      Output_section* data_section,
705                      Relocatable_relocs* rr)
706 {
707   gold_assert(parameters->options().relocatable()
708               || parameters->options().emit_relocs());
709
710   int sh_type = shdr.get_sh_type();
711
712   std::string name;
713   if (sh_type == elfcpp::SHT_REL)
714     name = ".rel";
715   else if (sh_type == elfcpp::SHT_RELA)
716     name = ".rela";
717   else
718     gold_unreachable();
719   name += data_section->name();
720
721   // In a relocatable link relocs for a grouped section must not be
722   // combined with other reloc sections.
723   Output_section* os;
724   if (!parameters->options().relocatable()
725       || (data_section->flags() & elfcpp::SHF_GROUP) == 0)
726     os = this->choose_output_section(object, name.c_str(), sh_type,
727                                      shdr.get_sh_flags(), false,
728                                      ORDER_INVALID, false);
729   else
730     {
731       const char* n = this->namepool_.add(name.c_str(), true, NULL);
732       os = this->make_output_section(n, sh_type, shdr.get_sh_flags(),
733                                      ORDER_INVALID, false);
734     }
735
736   os->set_should_link_to_symtab();
737   os->set_info_section(data_section);
738
739   Output_section_data* posd;
740   if (sh_type == elfcpp::SHT_REL)
741     {
742       os->set_entsize(elfcpp::Elf_sizes<size>::rel_size);
743       posd = new Output_relocatable_relocs<elfcpp::SHT_REL,
744                                            size,
745                                            big_endian>(rr);
746     }
747   else if (sh_type == elfcpp::SHT_RELA)
748     {
749       os->set_entsize(elfcpp::Elf_sizes<size>::rela_size);
750       posd = new Output_relocatable_relocs<elfcpp::SHT_RELA,
751                                            size,
752                                            big_endian>(rr);
753     }
754   else
755     gold_unreachable();
756
757   os->add_output_section_data(posd);
758   rr->set_output_data(posd);
759
760   return os;
761 }
762
763 // Handle a group section when doing a relocatable link.
764
765 template<int size, bool big_endian>
766 void
767 Layout::layout_group(Symbol_table* symtab,
768                      Sized_relobj<size, big_endian>* object,
769                      unsigned int,
770                      const char* group_section_name,
771                      const char* signature,
772                      const elfcpp::Shdr<size, big_endian>& shdr,
773                      elfcpp::Elf_Word flags,
774                      std::vector<unsigned int>* shndxes)
775 {
776   gold_assert(parameters->options().relocatable());
777   gold_assert(shdr.get_sh_type() == elfcpp::SHT_GROUP);
778   group_section_name = this->namepool_.add(group_section_name, true, NULL);
779   Output_section* os = this->make_output_section(group_section_name,
780                                                  elfcpp::SHT_GROUP,
781                                                  shdr.get_sh_flags(),
782                                                  ORDER_INVALID, false);
783
784   // We need to find a symbol with the signature in the symbol table.
785   // If we don't find one now, we need to look again later.
786   Symbol* sym = symtab->lookup(signature, NULL);
787   if (sym != NULL)
788     os->set_info_symndx(sym);
789   else
790     {
791       // Reserve some space to minimize reallocations.
792       if (this->group_signatures_.empty())
793         this->group_signatures_.reserve(this->number_of_input_files_ * 16);
794
795       // We will wind up using a symbol whose name is the signature.
796       // So just put the signature in the symbol name pool to save it.
797       signature = symtab->canonicalize_name(signature);
798       this->group_signatures_.push_back(Group_signature(os, signature));
799     }
800
801   os->set_should_link_to_symtab();
802   os->set_entsize(4);
803
804   section_size_type entry_count =
805     convert_to_section_size_type(shdr.get_sh_size() / 4);
806   Output_section_data* posd =
807     new Output_data_group<size, big_endian>(object, entry_count, flags,
808                                             shndxes);
809   os->add_output_section_data(posd);
810 }
811
812 // Special GNU handling of sections name .eh_frame.  They will
813 // normally hold exception frame data as defined by the C++ ABI
814 // (http://codesourcery.com/cxx-abi/).
815
816 template<int size, bool big_endian>
817 Output_section*
818 Layout::layout_eh_frame(Sized_relobj<size, big_endian>* object,
819                         const unsigned char* symbols,
820                         off_t symbols_size,
821                         const unsigned char* symbol_names,
822                         off_t symbol_names_size,
823                         unsigned int shndx,
824                         const elfcpp::Shdr<size, big_endian>& shdr,
825                         unsigned int reloc_shndx, unsigned int reloc_type,
826                         off_t* off)
827 {
828   gold_assert(shdr.get_sh_type() == elfcpp::SHT_PROGBITS);
829   gold_assert((shdr.get_sh_flags() & elfcpp::SHF_ALLOC) != 0);
830
831   const char* const name = ".eh_frame";
832   Output_section* os = this->choose_output_section(object, name,
833                                                    elfcpp::SHT_PROGBITS,
834                                                    elfcpp::SHF_ALLOC, false,
835                                                    ORDER_EHFRAME, false);
836   if (os == NULL)
837     return NULL;
838
839   if (this->eh_frame_section_ == NULL)
840     {
841       this->eh_frame_section_ = os;
842       this->eh_frame_data_ = new Eh_frame();
843
844       if (parameters->options().eh_frame_hdr())
845         {
846           Output_section* hdr_os =
847             this->choose_output_section(NULL, ".eh_frame_hdr",
848                                         elfcpp::SHT_PROGBITS,
849                                         elfcpp::SHF_ALLOC, false,
850                                         ORDER_EHFRAME, false);
851
852           if (hdr_os != NULL)
853             {
854               Eh_frame_hdr* hdr_posd = new Eh_frame_hdr(os,
855                                                         this->eh_frame_data_);
856               hdr_os->add_output_section_data(hdr_posd);
857
858               hdr_os->set_after_input_sections();
859
860               if (!this->script_options_->saw_phdrs_clause())
861                 {
862                   Output_segment* hdr_oseg;
863                   hdr_oseg = this->make_output_segment(elfcpp::PT_GNU_EH_FRAME,
864                                                        elfcpp::PF_R);
865                   hdr_oseg->add_output_section_to_nonload(hdr_os,
866                                                           elfcpp::PF_R);
867                 }
868
869               this->eh_frame_data_->set_eh_frame_hdr(hdr_posd);
870             }
871         }
872     }
873
874   gold_assert(this->eh_frame_section_ == os);
875
876   if (this->eh_frame_data_->add_ehframe_input_section(object,
877                                                       symbols,
878                                                       symbols_size,
879                                                       symbol_names,
880                                                       symbol_names_size,
881                                                       shndx,
882                                                       reloc_shndx,
883                                                       reloc_type))
884     {
885       os->update_flags_for_input_section(shdr.get_sh_flags());
886
887       // A writable .eh_frame section is a RELRO section.
888       if ((shdr.get_sh_flags() & elfcpp::SHF_WRITE) != 0)
889         os->set_is_relro();
890
891       // We found a .eh_frame section we are going to optimize, so now
892       // we can add the set of optimized sections to the output
893       // section.  We need to postpone adding this until we've found a
894       // section we can optimize so that the .eh_frame section in
895       // crtbegin.o winds up at the start of the output section.
896       if (!this->added_eh_frame_data_)
897         {
898           os->add_output_section_data(this->eh_frame_data_);
899           this->added_eh_frame_data_ = true;
900         }
901       *off = -1;
902     }
903   else
904     {
905       // We couldn't handle this .eh_frame section for some reason.
906       // Add it as a normal section.
907       bool saw_sections_clause = this->script_options_->saw_sections_clause();
908       *off = os->add_input_section(this, object, shndx, name, shdr, reloc_shndx,
909                                    saw_sections_clause);
910       this->have_added_input_section_ = true;
911     }
912
913   return os;
914 }
915
916 // Add POSD to an output section using NAME, TYPE, and FLAGS.  Return
917 // the output section.
918
919 Output_section*
920 Layout::add_output_section_data(const char* name, elfcpp::Elf_Word type,
921                                 elfcpp::Elf_Xword flags,
922                                 Output_section_data* posd,
923                                 Output_section_order order, bool is_relro)
924 {
925   Output_section* os = this->choose_output_section(NULL, name, type, flags,
926                                                    false, order, is_relro);
927   if (os != NULL)
928     os->add_output_section_data(posd);
929   return os;
930 }
931
932 // Map section flags to segment flags.
933
934 elfcpp::Elf_Word
935 Layout::section_flags_to_segment(elfcpp::Elf_Xword flags)
936 {
937   elfcpp::Elf_Word ret = elfcpp::PF_R;
938   if ((flags & elfcpp::SHF_WRITE) != 0)
939     ret |= elfcpp::PF_W;
940   if ((flags & elfcpp::SHF_EXECINSTR) != 0)
941     ret |= elfcpp::PF_X;
942   return ret;
943 }
944
945 // Sometimes we compress sections.  This is typically done for
946 // sections that are not part of normal program execution (such as
947 // .debug_* sections), and where the readers of these sections know
948 // how to deal with compressed sections.  This routine doesn't say for
949 // certain whether we'll compress -- it depends on commandline options
950 // as well -- just whether this section is a candidate for compression.
951 // (The Output_compressed_section class decides whether to compress
952 // a given section, and picks the name of the compressed section.)
953
954 static bool
955 is_compressible_debug_section(const char* secname)
956 {
957   return (is_prefix_of(".debug", secname));
958 }
959
960 // We may see compressed debug sections in input files.  Return TRUE
961 // if this is the name of a compressed debug section.
962
963 bool
964 is_compressed_debug_section(const char* secname)
965 {
966   return (is_prefix_of(".zdebug", secname));
967 }
968
969 // Make a new Output_section, and attach it to segments as
970 // appropriate.  ORDER is the order in which this section should
971 // appear in the output segment.  IS_RELRO is true if this is a relro
972 // (read-only after relocations) section.
973
974 Output_section*
975 Layout::make_output_section(const char* name, elfcpp::Elf_Word type,
976                             elfcpp::Elf_Xword flags,
977                             Output_section_order order, bool is_relro)
978 {
979   Output_section* os;
980   if ((flags & elfcpp::SHF_ALLOC) == 0
981       && strcmp(parameters->options().compress_debug_sections(), "none") != 0
982       && is_compressible_debug_section(name))
983     os = new Output_compressed_section(&parameters->options(), name, type,
984                                        flags);
985   else if ((flags & elfcpp::SHF_ALLOC) == 0
986            && parameters->options().strip_debug_non_line()
987            && strcmp(".debug_abbrev", name) == 0)
988     {
989       os = this->debug_abbrev_ = new Output_reduced_debug_abbrev_section(
990           name, type, flags);
991       if (this->debug_info_)
992         this->debug_info_->set_abbreviations(this->debug_abbrev_);
993     }
994   else if ((flags & elfcpp::SHF_ALLOC) == 0
995            && parameters->options().strip_debug_non_line()
996            && strcmp(".debug_info", name) == 0)
997     {
998       os = this->debug_info_ = new Output_reduced_debug_info_section(
999           name, type, flags);
1000       if (this->debug_abbrev_)
1001         this->debug_info_->set_abbreviations(this->debug_abbrev_);
1002     }
1003   else
1004     {
1005       // FIXME: const_cast is ugly.
1006       Target* target = const_cast<Target*>(&parameters->target());
1007       os = target->make_output_section(name, type, flags);
1008     }
1009
1010   // With -z relro, we have to recognize the special sections by name.
1011   // There is no other way.
1012   bool is_relro_local = false;
1013   if (!this->script_options_->saw_sections_clause()
1014       && parameters->options().relro()
1015       && type == elfcpp::SHT_PROGBITS
1016       && (flags & elfcpp::SHF_ALLOC) != 0
1017       && (flags & elfcpp::SHF_WRITE) != 0)
1018     {
1019       if (strcmp(name, ".data.rel.ro") == 0)
1020         is_relro = true;
1021       else if (strcmp(name, ".data.rel.ro.local") == 0)
1022         {
1023           is_relro = true;
1024           is_relro_local = true;
1025         }
1026       else if (type == elfcpp::SHT_INIT_ARRAY
1027                || type == elfcpp::SHT_FINI_ARRAY
1028                || type == elfcpp::SHT_PREINIT_ARRAY)
1029         is_relro = true;
1030       else if (strcmp(name, ".ctors") == 0
1031                || strcmp(name, ".dtors") == 0
1032                || strcmp(name, ".jcr") == 0)
1033         is_relro = true;
1034     }
1035
1036   if (is_relro)
1037     os->set_is_relro();
1038
1039   if (order == ORDER_INVALID && (flags & elfcpp::SHF_ALLOC) != 0)
1040     order = this->default_section_order(os, is_relro_local);
1041
1042   os->set_order(order);
1043
1044   parameters->target().new_output_section(os);
1045
1046   this->section_list_.push_back(os);
1047
1048   // The GNU linker by default sorts some sections by priority, so we
1049   // do the same.  We need to know that this might happen before we
1050   // attach any input sections.
1051   if (!this->script_options_->saw_sections_clause()
1052       && (strcmp(name, ".ctors") == 0
1053           || strcmp(name, ".dtors") == 0
1054           || strcmp(name, ".init_array") == 0
1055           || strcmp(name, ".fini_array") == 0))
1056     os->set_may_sort_attached_input_sections();
1057
1058   // Check for .stab*str sections, as .stab* sections need to link to
1059   // them.
1060   if (type == elfcpp::SHT_STRTAB
1061       && !this->have_stabstr_section_
1062       && strncmp(name, ".stab", 5) == 0
1063       && strcmp(name + strlen(name) - 3, "str") == 0)
1064     this->have_stabstr_section_ = true;
1065
1066   // If we have already attached the sections to segments, then we
1067   // need to attach this one now.  This happens for sections created
1068   // directly by the linker.
1069   if (this->sections_are_attached_)
1070     this->attach_section_to_segment(os);
1071
1072   return os;
1073 }
1074
1075 // Return the default order in which a section should be placed in an
1076 // output segment.  This function captures a lot of the ideas in
1077 // ld/scripttempl/elf.sc in the GNU linker.  Note that the order of a
1078 // linker created section is normally set when the section is created;
1079 // this function is used for input sections.
1080
1081 Output_section_order
1082 Layout::default_section_order(Output_section* os, bool is_relro_local)
1083 {
1084   gold_assert((os->flags() & elfcpp::SHF_ALLOC) != 0);
1085   bool is_write = (os->flags() & elfcpp::SHF_WRITE) != 0;
1086   bool is_execinstr = (os->flags() & elfcpp::SHF_EXECINSTR) != 0;
1087   bool is_bss = false;
1088
1089   switch (os->type())
1090     {
1091     default:
1092     case elfcpp::SHT_PROGBITS:
1093       break;
1094     case elfcpp::SHT_NOBITS:
1095       is_bss = true;
1096       break;
1097     case elfcpp::SHT_RELA:
1098     case elfcpp::SHT_REL:
1099       if (!is_write)
1100         return ORDER_DYNAMIC_RELOCS;
1101       break;
1102     case elfcpp::SHT_HASH:
1103     case elfcpp::SHT_DYNAMIC:
1104     case elfcpp::SHT_SHLIB:
1105     case elfcpp::SHT_DYNSYM:
1106     case elfcpp::SHT_GNU_HASH:
1107     case elfcpp::SHT_GNU_verdef:
1108     case elfcpp::SHT_GNU_verneed:
1109     case elfcpp::SHT_GNU_versym:
1110       if (!is_write)
1111         return ORDER_DYNAMIC_LINKER;
1112       break;
1113     case elfcpp::SHT_NOTE:
1114       return is_write ? ORDER_RW_NOTE : ORDER_RO_NOTE;
1115     }
1116
1117   if ((os->flags() & elfcpp::SHF_TLS) != 0)
1118     return is_bss ? ORDER_TLS_BSS : ORDER_TLS_DATA;
1119
1120   if (!is_bss && !is_write)
1121     {
1122       if (is_execinstr)
1123         {
1124           if (strcmp(os->name(), ".init") == 0)
1125             return ORDER_INIT;
1126           else if (strcmp(os->name(), ".fini") == 0)
1127             return ORDER_FINI;
1128         }
1129       return is_execinstr ? ORDER_TEXT : ORDER_READONLY;
1130     }
1131
1132   if (os->is_relro())
1133     return is_relro_local ? ORDER_RELRO_LOCAL : ORDER_RELRO;
1134
1135   if (os->is_small_section())
1136     return is_bss ? ORDER_SMALL_BSS : ORDER_SMALL_DATA;
1137   if (os->is_large_section())
1138     return is_bss ? ORDER_LARGE_BSS : ORDER_LARGE_DATA;
1139
1140   return is_bss ? ORDER_BSS : ORDER_DATA;
1141 }
1142
1143 // Attach output sections to segments.  This is called after we have
1144 // seen all the input sections.
1145
1146 void
1147 Layout::attach_sections_to_segments()
1148 {
1149   for (Section_list::iterator p = this->section_list_.begin();
1150        p != this->section_list_.end();
1151        ++p)
1152     this->attach_section_to_segment(*p);
1153
1154   this->sections_are_attached_ = true;
1155 }
1156
1157 // Attach an output section to a segment.
1158
1159 void
1160 Layout::attach_section_to_segment(Output_section* os)
1161 {
1162   if ((os->flags() & elfcpp::SHF_ALLOC) == 0)
1163     this->unattached_section_list_.push_back(os);
1164   else
1165     this->attach_allocated_section_to_segment(os);
1166 }
1167
1168 // Attach an allocated output section to a segment.
1169
1170 void
1171 Layout::attach_allocated_section_to_segment(Output_section* os)
1172 {
1173   elfcpp::Elf_Xword flags = os->flags();
1174   gold_assert((flags & elfcpp::SHF_ALLOC) != 0);
1175
1176   if (parameters->options().relocatable())
1177     return;
1178
1179   // If we have a SECTIONS clause, we can't handle the attachment to
1180   // segments until after we've seen all the sections.
1181   if (this->script_options_->saw_sections_clause())
1182     return;
1183
1184   gold_assert(!this->script_options_->saw_phdrs_clause());
1185
1186   // This output section goes into a PT_LOAD segment.
1187
1188   elfcpp::Elf_Word seg_flags = Layout::section_flags_to_segment(flags);
1189
1190   // Check for --section-start.
1191   uint64_t addr;
1192   bool is_address_set = parameters->options().section_start(os->name(), &addr);
1193
1194   // In general the only thing we really care about for PT_LOAD
1195   // segments is whether or not they are writable or executable,
1196   // so that is how we search for them.
1197   // Large data sections also go into their own PT_LOAD segment.
1198   // People who need segments sorted on some other basis will
1199   // have to use a linker script.
1200
1201   Segment_list::const_iterator p;
1202   for (p = this->segment_list_.begin();
1203        p != this->segment_list_.end();
1204        ++p)
1205     {
1206       if ((*p)->type() != elfcpp::PT_LOAD)
1207         continue;
1208       if (!parameters->options().omagic()
1209           && ((*p)->flags() & elfcpp::PF_W) != (seg_flags & elfcpp::PF_W))
1210         continue;
1211       if (parameters->options().rosegment()
1212           && ((*p)->flags() & elfcpp::PF_X) != (seg_flags & elfcpp::PF_X))
1213         continue;
1214       // If -Tbss was specified, we need to separate the data and BSS
1215       // segments.
1216       if (parameters->options().user_set_Tbss())
1217         {
1218           if ((os->type() == elfcpp::SHT_NOBITS)
1219               == (*p)->has_any_data_sections())
1220             continue;
1221         }
1222       if (os->is_large_data_section() && !(*p)->is_large_data_segment())
1223         continue;
1224
1225       if (is_address_set)
1226         {
1227           if ((*p)->are_addresses_set())
1228             continue;
1229
1230           (*p)->add_initial_output_data(os);
1231           (*p)->update_flags_for_output_section(seg_flags);
1232           (*p)->set_addresses(addr, addr);
1233           break;
1234         }
1235
1236       (*p)->add_output_section_to_load(this, os, seg_flags);
1237       break;
1238     }
1239
1240   if (p == this->segment_list_.end())
1241     {
1242       Output_segment* oseg = this->make_output_segment(elfcpp::PT_LOAD,
1243                                                        seg_flags);
1244       if (os->is_large_data_section())
1245         oseg->set_is_large_data_segment();
1246       oseg->add_output_section_to_load(this, os, seg_flags);
1247       if (is_address_set)
1248         oseg->set_addresses(addr, addr);
1249     }
1250
1251   // If we see a loadable SHT_NOTE section, we create a PT_NOTE
1252   // segment.
1253   if (os->type() == elfcpp::SHT_NOTE)
1254     {
1255       // See if we already have an equivalent PT_NOTE segment.
1256       for (p = this->segment_list_.begin();
1257            p != segment_list_.end();
1258            ++p)
1259         {
1260           if ((*p)->type() == elfcpp::PT_NOTE
1261               && (((*p)->flags() & elfcpp::PF_W)
1262                   == (seg_flags & elfcpp::PF_W)))
1263             {
1264               (*p)->add_output_section_to_nonload(os, seg_flags);
1265               break;
1266             }
1267         }
1268
1269       if (p == this->segment_list_.end())
1270         {
1271           Output_segment* oseg = this->make_output_segment(elfcpp::PT_NOTE,
1272                                                            seg_flags);
1273           oseg->add_output_section_to_nonload(os, seg_flags);
1274         }
1275     }
1276
1277   // If we see a loadable SHF_TLS section, we create a PT_TLS
1278   // segment.  There can only be one such segment.
1279   if ((flags & elfcpp::SHF_TLS) != 0)
1280     {
1281       if (this->tls_segment_ == NULL)
1282         this->make_output_segment(elfcpp::PT_TLS, seg_flags);
1283       this->tls_segment_->add_output_section_to_nonload(os, seg_flags);
1284     }
1285
1286   // If -z relro is in effect, and we see a relro section, we create a
1287   // PT_GNU_RELRO segment.  There can only be one such segment.
1288   if (os->is_relro() && parameters->options().relro())
1289     {
1290       gold_assert(seg_flags == (elfcpp::PF_R | elfcpp::PF_W));
1291       if (this->relro_segment_ == NULL)
1292         this->make_output_segment(elfcpp::PT_GNU_RELRO, seg_flags);
1293       this->relro_segment_->add_output_section_to_nonload(os, seg_flags);
1294     }
1295 }
1296
1297 // Make an output section for a script.
1298
1299 Output_section*
1300 Layout::make_output_section_for_script(
1301     const char* name,
1302     Script_sections::Section_type section_type)
1303 {
1304   name = this->namepool_.add(name, false, NULL);
1305   elfcpp::Elf_Xword sh_flags = elfcpp::SHF_ALLOC;
1306   if (section_type == Script_sections::ST_NOLOAD)
1307     sh_flags = 0;
1308   Output_section* os = this->make_output_section(name, elfcpp::SHT_PROGBITS,
1309                                                  sh_flags, ORDER_INVALID,
1310                                                  false);
1311   os->set_found_in_sections_clause();
1312   if (section_type == Script_sections::ST_NOLOAD)
1313     os->set_is_noload();
1314   return os;
1315 }
1316
1317 // Return the number of segments we expect to see.
1318
1319 size_t
1320 Layout::expected_segment_count() const
1321 {
1322   size_t ret = this->segment_list_.size();
1323
1324   // If we didn't see a SECTIONS clause in a linker script, we should
1325   // already have the complete list of segments.  Otherwise we ask the
1326   // SECTIONS clause how many segments it expects, and add in the ones
1327   // we already have (PT_GNU_STACK, PT_GNU_EH_FRAME, etc.)
1328
1329   if (!this->script_options_->saw_sections_clause())
1330     return ret;
1331   else
1332     {
1333       const Script_sections* ss = this->script_options_->script_sections();
1334       return ret + ss->expected_segment_count(this);
1335     }
1336 }
1337
1338 // Handle the .note.GNU-stack section at layout time.  SEEN_GNU_STACK
1339 // is whether we saw a .note.GNU-stack section in the object file.
1340 // GNU_STACK_FLAGS is the section flags.  The flags give the
1341 // protection required for stack memory.  We record this in an
1342 // executable as a PT_GNU_STACK segment.  If an object file does not
1343 // have a .note.GNU-stack segment, we must assume that it is an old
1344 // object.  On some targets that will force an executable stack.
1345
1346 void
1347 Layout::layout_gnu_stack(bool seen_gnu_stack, uint64_t gnu_stack_flags)
1348 {
1349   if (!seen_gnu_stack)
1350     this->input_without_gnu_stack_note_ = true;
1351   else
1352     {
1353       this->input_with_gnu_stack_note_ = true;
1354       if ((gnu_stack_flags & elfcpp::SHF_EXECINSTR) != 0)
1355         this->input_requires_executable_stack_ = true;
1356     }
1357 }
1358
1359 // Create automatic note sections.
1360
1361 void
1362 Layout::create_notes()
1363 {
1364   this->create_gold_note();
1365   this->create_executable_stack_info();
1366   this->create_build_id();
1367 }
1368
1369 // Create the dynamic sections which are needed before we read the
1370 // relocs.
1371
1372 void
1373 Layout::create_initial_dynamic_sections(Symbol_table* symtab)
1374 {
1375   if (parameters->doing_static_link())
1376     return;
1377
1378   this->dynamic_section_ = this->choose_output_section(NULL, ".dynamic",
1379                                                        elfcpp::SHT_DYNAMIC,
1380                                                        (elfcpp::SHF_ALLOC
1381                                                         | elfcpp::SHF_WRITE),
1382                                                        false, ORDER_RELRO,
1383                                                        true);
1384
1385   this->dynamic_symbol_ =
1386     symtab->define_in_output_data("_DYNAMIC", NULL, Symbol_table::PREDEFINED,
1387                                   this->dynamic_section_, 0, 0,
1388                                   elfcpp::STT_OBJECT, elfcpp::STB_LOCAL,
1389                                   elfcpp::STV_HIDDEN, 0, false, false);
1390
1391   this->dynamic_data_ =  new Output_data_dynamic(&this->dynpool_);
1392
1393   this->dynamic_section_->add_output_section_data(this->dynamic_data_);
1394 }
1395
1396 // For each output section whose name can be represented as C symbol,
1397 // define __start and __stop symbols for the section.  This is a GNU
1398 // extension.
1399
1400 void
1401 Layout::define_section_symbols(Symbol_table* symtab)
1402 {
1403   for (Section_list::const_iterator p = this->section_list_.begin();
1404        p != this->section_list_.end();
1405        ++p)
1406     {
1407       const char* const name = (*p)->name();
1408       if (is_cident(name))
1409         {
1410           const std::string name_string(name);
1411           const std::string start_name(cident_section_start_prefix
1412                                        + name_string);
1413           const std::string stop_name(cident_section_stop_prefix
1414                                       + name_string);
1415
1416           symtab->define_in_output_data(start_name.c_str(),
1417                                         NULL, // version
1418                                         Symbol_table::PREDEFINED,
1419                                         *p,
1420                                         0, // value
1421                                         0, // symsize
1422                                         elfcpp::STT_NOTYPE,
1423                                         elfcpp::STB_GLOBAL,
1424                                         elfcpp::STV_DEFAULT,
1425                                         0, // nonvis
1426                                         false, // offset_is_from_end
1427                                         true); // only_if_ref
1428
1429           symtab->define_in_output_data(stop_name.c_str(),
1430                                         NULL, // version
1431                                         Symbol_table::PREDEFINED,
1432                                         *p,
1433                                         0, // value
1434                                         0, // symsize
1435                                         elfcpp::STT_NOTYPE,
1436                                         elfcpp::STB_GLOBAL,
1437                                         elfcpp::STV_DEFAULT,
1438                                         0, // nonvis
1439                                         true, // offset_is_from_end
1440                                         true); // only_if_ref
1441         }
1442     }
1443 }
1444
1445 // Define symbols for group signatures.
1446
1447 void
1448 Layout::define_group_signatures(Symbol_table* symtab)
1449 {
1450   for (Group_signatures::iterator p = this->group_signatures_.begin();
1451        p != this->group_signatures_.end();
1452        ++p)
1453     {
1454       Symbol* sym = symtab->lookup(p->signature, NULL);
1455       if (sym != NULL)
1456         p->section->set_info_symndx(sym);
1457       else
1458         {
1459           // Force the name of the group section to the group
1460           // signature, and use the group's section symbol as the
1461           // signature symbol.
1462           if (strcmp(p->section->name(), p->signature) != 0)
1463             {
1464               const char* name = this->namepool_.add(p->signature,
1465                                                      true, NULL);
1466               p->section->set_name(name);
1467             }
1468           p->section->set_needs_symtab_index();
1469           p->section->set_info_section_symndx(p->section);
1470         }
1471     }
1472
1473   this->group_signatures_.clear();
1474 }
1475
1476 // Find the first read-only PT_LOAD segment, creating one if
1477 // necessary.
1478
1479 Output_segment*
1480 Layout::find_first_load_seg()
1481 {
1482   Output_segment* best = NULL;
1483   for (Segment_list::const_iterator p = this->segment_list_.begin();
1484        p != this->segment_list_.end();
1485        ++p)
1486     {
1487       if ((*p)->type() == elfcpp::PT_LOAD
1488           && ((*p)->flags() & elfcpp::PF_R) != 0
1489           && (parameters->options().omagic()
1490               || ((*p)->flags() & elfcpp::PF_W) == 0))
1491         {
1492           if (best == NULL || this->segment_precedes(*p, best))
1493             best = *p;
1494         }
1495     }
1496   if (best != NULL)
1497     return best;
1498
1499   gold_assert(!this->script_options_->saw_phdrs_clause());
1500
1501   Output_segment* load_seg = this->make_output_segment(elfcpp::PT_LOAD,
1502                                                        elfcpp::PF_R);
1503   return load_seg;
1504 }
1505
1506 // Save states of all current output segments.  Store saved states
1507 // in SEGMENT_STATES.
1508
1509 void
1510 Layout::save_segments(Segment_states* segment_states)
1511 {
1512   for (Segment_list::const_iterator p = this->segment_list_.begin();
1513        p != this->segment_list_.end();
1514        ++p)
1515     {
1516       Output_segment* segment = *p;
1517       // Shallow copy.
1518       Output_segment* copy = new Output_segment(*segment);
1519       (*segment_states)[segment] = copy;
1520     }
1521 }
1522
1523 // Restore states of output segments and delete any segment not found in
1524 // SEGMENT_STATES.
1525
1526 void
1527 Layout::restore_segments(const Segment_states* segment_states)
1528 {
1529   // Go through the segment list and remove any segment added in the
1530   // relaxation loop.
1531   this->tls_segment_ = NULL;
1532   this->relro_segment_ = NULL;
1533   Segment_list::iterator list_iter = this->segment_list_.begin();
1534   while (list_iter != this->segment_list_.end())
1535     {
1536       Output_segment* segment = *list_iter;
1537       Segment_states::const_iterator states_iter =
1538           segment_states->find(segment);
1539       if (states_iter != segment_states->end())
1540         {
1541           const Output_segment* copy = states_iter->second;
1542           // Shallow copy to restore states.
1543           *segment = *copy;
1544
1545           // Also fix up TLS and RELRO segment pointers as appropriate.
1546           if (segment->type() == elfcpp::PT_TLS)
1547             this->tls_segment_ = segment;
1548           else if (segment->type() == elfcpp::PT_GNU_RELRO)
1549             this->relro_segment_ = segment;
1550
1551           ++list_iter;
1552         } 
1553       else
1554         {
1555           list_iter = this->segment_list_.erase(list_iter); 
1556           // This is a segment created during section layout.  It should be
1557           // safe to remove it since we should have removed all pointers to it.
1558           delete segment;
1559         }
1560     }
1561 }
1562
1563 // Clean up after relaxation so that sections can be laid out again.
1564
1565 void
1566 Layout::clean_up_after_relaxation()
1567 {
1568   // Restore the segments to point state just prior to the relaxation loop.
1569   Script_sections* script_section = this->script_options_->script_sections();
1570   script_section->release_segments();
1571   this->restore_segments(this->segment_states_);
1572
1573   // Reset section addresses and file offsets
1574   for (Section_list::iterator p = this->section_list_.begin();
1575        p != this->section_list_.end();
1576        ++p)
1577     {
1578       (*p)->restore_states();
1579
1580       // If an input section changes size because of relaxation,
1581       // we need to adjust the section offsets of all input sections.
1582       // after such a section.
1583       if ((*p)->section_offsets_need_adjustment())
1584         (*p)->adjust_section_offsets();
1585
1586       (*p)->reset_address_and_file_offset();
1587     }
1588   
1589   // Reset special output object address and file offsets.
1590   for (Data_list::iterator p = this->special_output_list_.begin();
1591        p != this->special_output_list_.end();
1592        ++p)
1593     (*p)->reset_address_and_file_offset();
1594
1595   // A linker script may have created some output section data objects.
1596   // They are useless now.
1597   for (Output_section_data_list::const_iterator p =
1598          this->script_output_section_data_list_.begin();
1599        p != this->script_output_section_data_list_.end();
1600        ++p)
1601     delete *p;
1602   this->script_output_section_data_list_.clear(); 
1603 }
1604
1605 // Prepare for relaxation.
1606
1607 void
1608 Layout::prepare_for_relaxation()
1609 {
1610   // Create an relaxation debug check if in debugging mode.
1611   if (is_debugging_enabled(DEBUG_RELAXATION))
1612     this->relaxation_debug_check_ = new Relaxation_debug_check();
1613
1614   // Save segment states.
1615   this->segment_states_ = new Segment_states();
1616   this->save_segments(this->segment_states_);
1617
1618   for(Section_list::const_iterator p = this->section_list_.begin();
1619       p != this->section_list_.end();
1620       ++p)
1621     (*p)->save_states();
1622
1623   if (is_debugging_enabled(DEBUG_RELAXATION))
1624     this->relaxation_debug_check_->check_output_data_for_reset_values(
1625         this->section_list_, this->special_output_list_);
1626
1627   // Also enable recording of output section data from scripts.
1628   this->record_output_section_data_from_script_ = true;
1629 }
1630
1631 // Relaxation loop body:  If target has no relaxation, this runs only once
1632 // Otherwise, the target relaxation hook is called at the end of
1633 // each iteration.  If the hook returns true, it means re-layout of
1634 // section is required.  
1635 //
1636 // The number of segments created by a linking script without a PHDRS
1637 // clause may be affected by section sizes and alignments.  There is
1638 // a remote chance that relaxation causes different number of PT_LOAD
1639 // segments are created and sections are attached to different segments.
1640 // Therefore, we always throw away all segments created during section
1641 // layout.  In order to be able to restart the section layout, we keep
1642 // a copy of the segment list right before the relaxation loop and use
1643 // that to restore the segments.
1644 // 
1645 // PASS is the current relaxation pass number. 
1646 // SYMTAB is a symbol table.
1647 // PLOAD_SEG is the address of a pointer for the load segment.
1648 // PHDR_SEG is a pointer to the PHDR segment.
1649 // SEGMENT_HEADERS points to the output segment header.
1650 // FILE_HEADER points to the output file header.
1651 // PSHNDX is the address to store the output section index.
1652
1653 off_t inline
1654 Layout::relaxation_loop_body(
1655     int pass,
1656     Target* target,
1657     Symbol_table* symtab,
1658     Output_segment** pload_seg,
1659     Output_segment* phdr_seg,
1660     Output_segment_headers* segment_headers,
1661     Output_file_header* file_header,
1662     unsigned int* pshndx)
1663 {
1664   // If this is not the first iteration, we need to clean up after
1665   // relaxation so that we can lay out the sections again.
1666   if (pass != 0)
1667     this->clean_up_after_relaxation();
1668
1669   // If there is a SECTIONS clause, put all the input sections into
1670   // the required order.
1671   Output_segment* load_seg;
1672   if (this->script_options_->saw_sections_clause())
1673     load_seg = this->set_section_addresses_from_script(symtab);
1674   else if (parameters->options().relocatable())
1675     load_seg = NULL;
1676   else
1677     load_seg = this->find_first_load_seg();
1678
1679   if (parameters->options().oformat_enum()
1680       != General_options::OBJECT_FORMAT_ELF)
1681     load_seg = NULL;
1682
1683   // If the user set the address of the text segment, that may not be
1684   // compatible with putting the segment headers and file headers into
1685   // that segment.
1686   if (parameters->options().user_set_Ttext())
1687     load_seg = NULL;
1688
1689   gold_assert(phdr_seg == NULL
1690               || load_seg != NULL
1691               || this->script_options_->saw_sections_clause());
1692
1693   // If the address of the load segment we found has been set by
1694   // --section-start rather than by a script, then adjust the VMA and
1695   // LMA downward if possible to include the file and section headers.
1696   uint64_t header_gap = 0;
1697   if (load_seg != NULL
1698       && load_seg->are_addresses_set()
1699       && !this->script_options_->saw_sections_clause()
1700       && !parameters->options().relocatable())
1701     {
1702       file_header->finalize_data_size();
1703       segment_headers->finalize_data_size();
1704       size_t sizeof_headers = (file_header->data_size()
1705                                + segment_headers->data_size());
1706       const uint64_t abi_pagesize = target->abi_pagesize();
1707       uint64_t hdr_paddr = load_seg->paddr() - sizeof_headers;
1708       hdr_paddr &= ~(abi_pagesize - 1);
1709       uint64_t subtract = load_seg->paddr() - hdr_paddr;
1710       if (load_seg->paddr() < subtract || load_seg->vaddr() < subtract)
1711         load_seg = NULL;
1712       else
1713         {
1714           load_seg->set_addresses(load_seg->vaddr() - subtract,
1715                                   load_seg->paddr() - subtract);
1716           header_gap = subtract - sizeof_headers;
1717         }
1718     }
1719
1720   // Lay out the segment headers.
1721   if (!parameters->options().relocatable())
1722     {
1723       gold_assert(segment_headers != NULL);
1724       if (header_gap != 0 && load_seg != NULL)
1725         {
1726           Output_data_zero_fill* z = new Output_data_zero_fill(header_gap, 1);
1727           load_seg->add_initial_output_data(z);
1728         }
1729       if (load_seg != NULL)
1730         load_seg->add_initial_output_data(segment_headers);
1731       if (phdr_seg != NULL)
1732         phdr_seg->add_initial_output_data(segment_headers);
1733     }
1734
1735   // Lay out the file header.
1736   if (load_seg != NULL)
1737     load_seg->add_initial_output_data(file_header);
1738
1739   if (this->script_options_->saw_phdrs_clause()
1740       && !parameters->options().relocatable())
1741     {
1742       // Support use of FILEHDRS and PHDRS attachments in a PHDRS
1743       // clause in a linker script.
1744       Script_sections* ss = this->script_options_->script_sections();
1745       ss->put_headers_in_phdrs(file_header, segment_headers);
1746     }
1747
1748   // We set the output section indexes in set_segment_offsets and
1749   // set_section_indexes.
1750   *pshndx = 1;
1751
1752   // Set the file offsets of all the segments, and all the sections
1753   // they contain.
1754   off_t off;
1755   if (!parameters->options().relocatable())
1756     off = this->set_segment_offsets(target, load_seg, pshndx);
1757   else
1758     off = this->set_relocatable_section_offsets(file_header, pshndx);
1759
1760    // Verify that the dummy relaxation does not change anything.
1761   if (is_debugging_enabled(DEBUG_RELAXATION))
1762     {
1763       if (pass == 0)
1764         this->relaxation_debug_check_->read_sections(this->section_list_);
1765       else
1766         this->relaxation_debug_check_->verify_sections(this->section_list_);
1767     }
1768
1769   *pload_seg = load_seg;
1770   return off;
1771 }
1772
1773 // Search the list of patterns and find the postion of the given section
1774 // name in the output section.  If the section name matches a glob
1775 // pattern and a non-glob name, then the non-glob position takes
1776 // precedence.  Return 0 if no match is found.
1777
1778 unsigned int
1779 Layout::find_section_order_index(const std::string& section_name)
1780 {
1781   Unordered_map<std::string, unsigned int>::iterator map_it;
1782   map_it = this->input_section_position_.find(section_name);
1783   if (map_it != this->input_section_position_.end())
1784     return map_it->second;
1785
1786   // Absolute match failed.  Linear search the glob patterns.
1787   std::vector<std::string>::iterator it;
1788   for (it = this->input_section_glob_.begin();
1789        it != this->input_section_glob_.end();
1790        ++it)
1791     {
1792        if (fnmatch((*it).c_str(), section_name.c_str(), FNM_NOESCAPE) == 0)
1793          {
1794            map_it = this->input_section_position_.find(*it);
1795            gold_assert(map_it != this->input_section_position_.end());
1796            return map_it->second;
1797          }
1798     }
1799   return 0;
1800 }
1801
1802 // Read the sequence of input sections from the file specified with
1803 // --section-ordering-file.
1804
1805 void
1806 Layout::read_layout_from_file()
1807 {
1808   const char* filename = parameters->options().section_ordering_file();
1809   std::ifstream in;
1810   std::string line;
1811
1812   in.open(filename);
1813   if (!in)
1814     gold_fatal(_("unable to open --section-ordering-file file %s: %s"),
1815                filename, strerror(errno));
1816
1817   std::getline(in, line);   // this chops off the trailing \n, if any
1818   unsigned int position = 1;
1819
1820   while (in)
1821     {
1822       if (!line.empty() && line[line.length() - 1] == '\r')   // Windows
1823         line.resize(line.length() - 1);
1824       // Ignore comments, beginning with '#'
1825       if (line[0] == '#')
1826         {
1827           std::getline(in, line);
1828           continue;
1829         }
1830       this->input_section_position_[line] = position;
1831       // Store all glob patterns in a vector.
1832       if (is_wildcard_string(line.c_str()))
1833         this->input_section_glob_.push_back(line);
1834       position++;
1835       std::getline(in, line);
1836     }
1837 }
1838
1839 // Finalize the layout.  When this is called, we have created all the
1840 // output sections and all the output segments which are based on
1841 // input sections.  We have several things to do, and we have to do
1842 // them in the right order, so that we get the right results correctly
1843 // and efficiently.
1844
1845 // 1) Finalize the list of output segments and create the segment
1846 // table header.
1847
1848 // 2) Finalize the dynamic symbol table and associated sections.
1849
1850 // 3) Determine the final file offset of all the output segments.
1851
1852 // 4) Determine the final file offset of all the SHF_ALLOC output
1853 // sections.
1854
1855 // 5) Create the symbol table sections and the section name table
1856 // section.
1857
1858 // 6) Finalize the symbol table: set symbol values to their final
1859 // value and make a final determination of which symbols are going
1860 // into the output symbol table.
1861
1862 // 7) Create the section table header.
1863
1864 // 8) Determine the final file offset of all the output sections which
1865 // are not SHF_ALLOC, including the section table header.
1866
1867 // 9) Finalize the ELF file header.
1868
1869 // This function returns the size of the output file.
1870
1871 off_t
1872 Layout::finalize(const Input_objects* input_objects, Symbol_table* symtab,
1873                  Target* target, const Task* task)
1874 {
1875   target->finalize_sections(this, input_objects, symtab);
1876
1877   this->count_local_symbols(task, input_objects);
1878
1879   this->link_stabs_sections();
1880
1881   Output_segment* phdr_seg = NULL;
1882   if (!parameters->options().relocatable() && !parameters->doing_static_link())
1883     {
1884       // There was a dynamic object in the link.  We need to create
1885       // some information for the dynamic linker.
1886
1887       // Create the PT_PHDR segment which will hold the program
1888       // headers.
1889       if (!this->script_options_->saw_phdrs_clause())
1890         phdr_seg = this->make_output_segment(elfcpp::PT_PHDR, elfcpp::PF_R);
1891
1892       // Create the dynamic symbol table, including the hash table.
1893       Output_section* dynstr;
1894       std::vector<Symbol*> dynamic_symbols;
1895       unsigned int local_dynamic_count;
1896       Versions versions(*this->script_options()->version_script_info(),
1897                         &this->dynpool_);
1898       this->create_dynamic_symtab(input_objects, symtab, &dynstr,
1899                                   &local_dynamic_count, &dynamic_symbols,
1900                                   &versions);
1901
1902       // Create the .interp section to hold the name of the
1903       // interpreter, and put it in a PT_INTERP segment.
1904       if (!parameters->options().shared())
1905         this->create_interp(target);
1906
1907       // Finish the .dynamic section to hold the dynamic data, and put
1908       // it in a PT_DYNAMIC segment.
1909       this->finish_dynamic_section(input_objects, symtab);
1910
1911       // We should have added everything we need to the dynamic string
1912       // table.
1913       this->dynpool_.set_string_offsets();
1914
1915       // Create the version sections.  We can't do this until the
1916       // dynamic string table is complete.
1917       this->create_version_sections(&versions, symtab, local_dynamic_count,
1918                                     dynamic_symbols, dynstr);
1919
1920       // Set the size of the _DYNAMIC symbol.  We can't do this until
1921       // after we call create_version_sections.
1922       this->set_dynamic_symbol_size(symtab);
1923     }
1924   
1925   // Create segment headers.
1926   Output_segment_headers* segment_headers =
1927     (parameters->options().relocatable()
1928      ? NULL
1929      : new Output_segment_headers(this->segment_list_));
1930
1931   // Lay out the file header.
1932   Output_file_header* file_header
1933     = new Output_file_header(target, symtab, segment_headers,
1934                              parameters->options().entry());
1935
1936   this->special_output_list_.push_back(file_header);
1937   if (segment_headers != NULL)
1938     this->special_output_list_.push_back(segment_headers);
1939
1940   // Find approriate places for orphan output sections if we are using
1941   // a linker script.
1942   if (this->script_options_->saw_sections_clause())
1943     this->place_orphan_sections_in_script();
1944   
1945   Output_segment* load_seg;
1946   off_t off;
1947   unsigned int shndx;
1948   int pass = 0;
1949
1950   // Take a snapshot of the section layout as needed.
1951   if (target->may_relax())
1952     this->prepare_for_relaxation();
1953   
1954   // Run the relaxation loop to lay out sections.
1955   do
1956     {
1957       off = this->relaxation_loop_body(pass, target, symtab, &load_seg,
1958                                        phdr_seg, segment_headers, file_header,
1959                                        &shndx);
1960       pass++;
1961     }
1962   while (target->may_relax()
1963          && target->relax(pass, input_objects, symtab, this));
1964
1965   // Set the file offsets of all the non-data sections we've seen so
1966   // far which don't have to wait for the input sections.  We need
1967   // this in order to finalize local symbols in non-allocated
1968   // sections.
1969   off = this->set_section_offsets(off, BEFORE_INPUT_SECTIONS_PASS);
1970
1971   // Set the section indexes of all unallocated sections seen so far,
1972   // in case any of them are somehow referenced by a symbol.
1973   shndx = this->set_section_indexes(shndx);
1974
1975   // Create the symbol table sections.
1976   this->create_symtab_sections(input_objects, symtab, shndx, &off);
1977   if (!parameters->doing_static_link())
1978     this->assign_local_dynsym_offsets(input_objects);
1979
1980   // Process any symbol assignments from a linker script.  This must
1981   // be called after the symbol table has been finalized.
1982   this->script_options_->finalize_symbols(symtab, this);
1983
1984   // Create the incremental inputs sections.
1985   if (this->incremental_inputs_)
1986     {
1987       this->incremental_inputs_->finalize();
1988       this->create_incremental_info_sections(symtab);
1989     }
1990
1991   // Create the .shstrtab section.
1992   Output_section* shstrtab_section = this->create_shstrtab();
1993
1994   // Set the file offsets of the rest of the non-data sections which
1995   // don't have to wait for the input sections.
1996   off = this->set_section_offsets(off, BEFORE_INPUT_SECTIONS_PASS);
1997
1998   // Now that all sections have been created, set the section indexes
1999   // for any sections which haven't been done yet.
2000   shndx = this->set_section_indexes(shndx);
2001
2002   // Create the section table header.
2003   this->create_shdrs(shstrtab_section, &off);
2004
2005   // If there are no sections which require postprocessing, we can
2006   // handle the section names now, and avoid a resize later.
2007   if (!this->any_postprocessing_sections_)
2008     {
2009       off = this->set_section_offsets(off,
2010                                       POSTPROCESSING_SECTIONS_PASS);
2011       off =
2012           this->set_section_offsets(off,
2013                                     STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS);
2014     }
2015
2016   file_header->set_section_info(this->section_headers_, shstrtab_section);
2017
2018   // Now we know exactly where everything goes in the output file
2019   // (except for non-allocated sections which require postprocessing).
2020   Output_data::layout_complete();
2021
2022   this->output_file_size_ = off;
2023
2024   return off;
2025 }
2026
2027 // Create a note header following the format defined in the ELF ABI.
2028 // NAME is the name, NOTE_TYPE is the type, SECTION_NAME is the name
2029 // of the section to create, DESCSZ is the size of the descriptor.
2030 // ALLOCATE is true if the section should be allocated in memory.
2031 // This returns the new note section.  It sets *TRAILING_PADDING to
2032 // the number of trailing zero bytes required.
2033
2034 Output_section*
2035 Layout::create_note(const char* name, int note_type,
2036                     const char* section_name, size_t descsz,
2037                     bool allocate, size_t* trailing_padding)
2038 {
2039   // Authorities all agree that the values in a .note field should
2040   // be aligned on 4-byte boundaries for 32-bit binaries.  However,
2041   // they differ on what the alignment is for 64-bit binaries.
2042   // The GABI says unambiguously they take 8-byte alignment:
2043   //    http://sco.com/developers/gabi/latest/ch5.pheader.html#note_section
2044   // Other documentation says alignment should always be 4 bytes:
2045   //    http://www.netbsd.org/docs/kernel/elf-notes.html#note-format
2046   // GNU ld and GNU readelf both support the latter (at least as of
2047   // version 2.16.91), and glibc always generates the latter for
2048   // .note.ABI-tag (as of version 1.6), so that's the one we go with
2049   // here.
2050 #ifdef GABI_FORMAT_FOR_DOTNOTE_SECTION   // This is not defined by default.
2051   const int size = parameters->target().get_size();
2052 #else
2053   const int size = 32;
2054 #endif
2055
2056   // The contents of the .note section.
2057   size_t namesz = strlen(name) + 1;
2058   size_t aligned_namesz = align_address(namesz, size / 8);
2059   size_t aligned_descsz = align_address(descsz, size / 8);
2060
2061   size_t notehdrsz = 3 * (size / 8) + aligned_namesz;
2062
2063   unsigned char* buffer = new unsigned char[notehdrsz];
2064   memset(buffer, 0, notehdrsz);
2065
2066   bool is_big_endian = parameters->target().is_big_endian();
2067
2068   if (size == 32)
2069     {
2070       if (!is_big_endian)
2071         {
2072           elfcpp::Swap<32, false>::writeval(buffer, namesz);
2073           elfcpp::Swap<32, false>::writeval(buffer + 4, descsz);
2074           elfcpp::Swap<32, false>::writeval(buffer + 8, note_type);
2075         }
2076       else
2077         {
2078           elfcpp::Swap<32, true>::writeval(buffer, namesz);
2079           elfcpp::Swap<32, true>::writeval(buffer + 4, descsz);
2080           elfcpp::Swap<32, true>::writeval(buffer + 8, note_type);
2081         }
2082     }
2083   else if (size == 64)
2084     {
2085       if (!is_big_endian)
2086         {
2087           elfcpp::Swap<64, false>::writeval(buffer, namesz);
2088           elfcpp::Swap<64, false>::writeval(buffer + 8, descsz);
2089           elfcpp::Swap<64, false>::writeval(buffer + 16, note_type);
2090         }
2091       else
2092         {
2093           elfcpp::Swap<64, true>::writeval(buffer, namesz);
2094           elfcpp::Swap<64, true>::writeval(buffer + 8, descsz);
2095           elfcpp::Swap<64, true>::writeval(buffer + 16, note_type);
2096         }
2097     }
2098   else
2099     gold_unreachable();
2100
2101   memcpy(buffer + 3 * (size / 8), name, namesz);
2102
2103   elfcpp::Elf_Xword flags = 0;
2104   Output_section_order order = ORDER_INVALID;
2105   if (allocate)
2106     {
2107       flags = elfcpp::SHF_ALLOC;
2108       order = ORDER_RO_NOTE;
2109     }
2110   Output_section* os = this->choose_output_section(NULL, section_name,
2111                                                    elfcpp::SHT_NOTE,
2112                                                    flags, false, order, false);
2113   if (os == NULL)
2114     return NULL;
2115
2116   Output_section_data* posd = new Output_data_const_buffer(buffer, notehdrsz,
2117                                                            size / 8,
2118                                                            "** note header");
2119   os->add_output_section_data(posd);
2120
2121   *trailing_padding = aligned_descsz - descsz;
2122
2123   return os;
2124 }
2125
2126 // For an executable or shared library, create a note to record the
2127 // version of gold used to create the binary.
2128
2129 void
2130 Layout::create_gold_note()
2131 {
2132   if (parameters->options().relocatable())
2133     return;
2134
2135   std::string desc = std::string("gold ") + gold::get_version_string();
2136
2137   size_t trailing_padding;
2138   Output_section* os = this->create_note("GNU", elfcpp::NT_GNU_GOLD_VERSION,
2139                                          ".note.gnu.gold-version", desc.size(),
2140                                          false, &trailing_padding);
2141   if (os == NULL)
2142     return;
2143
2144   Output_section_data* posd = new Output_data_const(desc, 4);
2145   os->add_output_section_data(posd);
2146
2147   if (trailing_padding > 0)
2148     {
2149       posd = new Output_data_zero_fill(trailing_padding, 0);
2150       os->add_output_section_data(posd);
2151     }
2152 }
2153
2154 // Record whether the stack should be executable.  This can be set
2155 // from the command line using the -z execstack or -z noexecstack
2156 // options.  Otherwise, if any input file has a .note.GNU-stack
2157 // section with the SHF_EXECINSTR flag set, the stack should be
2158 // executable.  Otherwise, if at least one input file a
2159 // .note.GNU-stack section, and some input file has no .note.GNU-stack
2160 // section, we use the target default for whether the stack should be
2161 // executable.  Otherwise, we don't generate a stack note.  When
2162 // generating a object file, we create a .note.GNU-stack section with
2163 // the appropriate marking.  When generating an executable or shared
2164 // library, we create a PT_GNU_STACK segment.
2165
2166 void
2167 Layout::create_executable_stack_info()
2168 {
2169   bool is_stack_executable;
2170   if (parameters->options().is_execstack_set())
2171     is_stack_executable = parameters->options().is_stack_executable();
2172   else if (!this->input_with_gnu_stack_note_)
2173     return;
2174   else
2175     {
2176       if (this->input_requires_executable_stack_)
2177         is_stack_executable = true;
2178       else if (this->input_without_gnu_stack_note_)
2179         is_stack_executable =
2180           parameters->target().is_default_stack_executable();
2181       else
2182         is_stack_executable = false;
2183     }
2184
2185   if (parameters->options().relocatable())
2186     {
2187       const char* name = this->namepool_.add(".note.GNU-stack", false, NULL);
2188       elfcpp::Elf_Xword flags = 0;
2189       if (is_stack_executable)
2190         flags |= elfcpp::SHF_EXECINSTR;
2191       this->make_output_section(name, elfcpp::SHT_PROGBITS, flags,
2192                                 ORDER_INVALID, false);
2193     }
2194   else
2195     {
2196       if (this->script_options_->saw_phdrs_clause())
2197         return;
2198       int flags = elfcpp::PF_R | elfcpp::PF_W;
2199       if (is_stack_executable)
2200         flags |= elfcpp::PF_X;
2201       this->make_output_segment(elfcpp::PT_GNU_STACK, flags);
2202     }
2203 }
2204
2205 // If --build-id was used, set up the build ID note.
2206
2207 void
2208 Layout::create_build_id()
2209 {
2210   if (!parameters->options().user_set_build_id())
2211     return;
2212
2213   const char* style = parameters->options().build_id();
2214   if (strcmp(style, "none") == 0)
2215     return;
2216
2217   // Set DESCSZ to the size of the note descriptor.  When possible,
2218   // set DESC to the note descriptor contents.
2219   size_t descsz;
2220   std::string desc;
2221   if (strcmp(style, "md5") == 0)
2222     descsz = 128 / 8;
2223   else if (strcmp(style, "sha1") == 0)
2224     descsz = 160 / 8;
2225   else if (strcmp(style, "uuid") == 0)
2226     {
2227       const size_t uuidsz = 128 / 8;
2228
2229       char buffer[uuidsz];
2230       memset(buffer, 0, uuidsz);
2231
2232       int descriptor = open_descriptor(-1, "/dev/urandom", O_RDONLY);
2233       if (descriptor < 0)
2234         gold_error(_("--build-id=uuid failed: could not open /dev/urandom: %s"),
2235                    strerror(errno));
2236       else
2237         {
2238           ssize_t got = ::read(descriptor, buffer, uuidsz);
2239           release_descriptor(descriptor, true);
2240           if (got < 0)
2241             gold_error(_("/dev/urandom: read failed: %s"), strerror(errno));
2242           else if (static_cast<size_t>(got) != uuidsz)
2243             gold_error(_("/dev/urandom: expected %zu bytes, got %zd bytes"),
2244                        uuidsz, got);
2245         }
2246
2247       desc.assign(buffer, uuidsz);
2248       descsz = uuidsz;
2249     }
2250   else if (strncmp(style, "0x", 2) == 0)
2251     {
2252       hex_init();
2253       const char* p = style + 2;
2254       while (*p != '\0')
2255         {
2256           if (hex_p(p[0]) && hex_p(p[1]))
2257             {
2258               char c = (hex_value(p[0]) << 4) | hex_value(p[1]);
2259               desc += c;
2260               p += 2;
2261             }
2262           else if (*p == '-' || *p == ':')
2263             ++p;
2264           else
2265             gold_fatal(_("--build-id argument '%s' not a valid hex number"),
2266                        style);
2267         }
2268       descsz = desc.size();
2269     }
2270   else
2271     gold_fatal(_("unrecognized --build-id argument '%s'"), style);
2272
2273   // Create the note.
2274   size_t trailing_padding;
2275   Output_section* os = this->create_note("GNU", elfcpp::NT_GNU_BUILD_ID,
2276                                          ".note.gnu.build-id", descsz, true,
2277                                          &trailing_padding);
2278   if (os == NULL)
2279     return;
2280
2281   if (!desc.empty())
2282     {
2283       // We know the value already, so we fill it in now.
2284       gold_assert(desc.size() == descsz);
2285
2286       Output_section_data* posd = new Output_data_const(desc, 4);
2287       os->add_output_section_data(posd);
2288
2289       if (trailing_padding != 0)
2290         {
2291           posd = new Output_data_zero_fill(trailing_padding, 0);
2292           os->add_output_section_data(posd);
2293         }
2294     }
2295   else
2296     {
2297       // We need to compute a checksum after we have completed the
2298       // link.
2299       gold_assert(trailing_padding == 0);
2300       this->build_id_note_ = new Output_data_zero_fill(descsz, 4);
2301       os->add_output_section_data(this->build_id_note_);
2302     }
2303 }
2304
2305 // If we have both .stabXX and .stabXXstr sections, then the sh_link
2306 // field of the former should point to the latter.  I'm not sure who
2307 // started this, but the GNU linker does it, and some tools depend
2308 // upon it.
2309
2310 void
2311 Layout::link_stabs_sections()
2312 {
2313   if (!this->have_stabstr_section_)
2314     return;
2315
2316   for (Section_list::iterator p = this->section_list_.begin();
2317        p != this->section_list_.end();
2318        ++p)
2319     {
2320       if ((*p)->type() != elfcpp::SHT_STRTAB)
2321         continue;
2322
2323       const char* name = (*p)->name();
2324       if (strncmp(name, ".stab", 5) != 0)
2325         continue;
2326
2327       size_t len = strlen(name);
2328       if (strcmp(name + len - 3, "str") != 0)
2329         continue;
2330
2331       std::string stab_name(name, len - 3);
2332       Output_section* stab_sec;
2333       stab_sec = this->find_output_section(stab_name.c_str());
2334       if (stab_sec != NULL)
2335         stab_sec->set_link_section(*p);
2336     }
2337 }
2338
2339 // Create .gnu_incremental_inputs and related sections needed
2340 // for the next run of incremental linking to check what has changed.
2341
2342 void
2343 Layout::create_incremental_info_sections(Symbol_table* symtab)
2344 {
2345   Incremental_inputs* incr = this->incremental_inputs_;
2346
2347   gold_assert(incr != NULL);
2348
2349   // Create the .gnu_incremental_inputs, _symtab, and _relocs input sections.
2350   incr->create_data_sections(symtab);
2351
2352   // Add the .gnu_incremental_inputs section.
2353   const char* incremental_inputs_name =
2354     this->namepool_.add(".gnu_incremental_inputs", false, NULL);
2355   Output_section* incremental_inputs_os =
2356     this->make_output_section(incremental_inputs_name,
2357                               elfcpp::SHT_GNU_INCREMENTAL_INPUTS, 0,
2358                               ORDER_INVALID, false);
2359   incremental_inputs_os->add_output_section_data(incr->inputs_section());
2360
2361   // Add the .gnu_incremental_symtab section.
2362   const char* incremental_symtab_name =
2363     this->namepool_.add(".gnu_incremental_symtab", false, NULL);
2364   Output_section* incremental_symtab_os =
2365     this->make_output_section(incremental_symtab_name,
2366                               elfcpp::SHT_GNU_INCREMENTAL_SYMTAB, 0,
2367                               ORDER_INVALID, false);
2368   incremental_symtab_os->add_output_section_data(incr->symtab_section());
2369   incremental_symtab_os->set_entsize(4);
2370
2371   // Add the .gnu_incremental_relocs section.
2372   const char* incremental_relocs_name =
2373     this->namepool_.add(".gnu_incremental_relocs", false, NULL);
2374   Output_section* incremental_relocs_os =
2375     this->make_output_section(incremental_relocs_name,
2376                               elfcpp::SHT_GNU_INCREMENTAL_RELOCS, 0,
2377                               ORDER_INVALID, false);
2378   incremental_relocs_os->add_output_section_data(incr->relocs_section());
2379   incremental_relocs_os->set_entsize(incr->relocs_entsize());
2380
2381   // Add the .gnu_incremental_got_plt section.
2382   const char* incremental_got_plt_name =
2383     this->namepool_.add(".gnu_incremental_got_plt", false, NULL);
2384   Output_section* incremental_got_plt_os =
2385     this->make_output_section(incremental_got_plt_name,
2386                               elfcpp::SHT_GNU_INCREMENTAL_GOT_PLT, 0,
2387                               ORDER_INVALID, false);
2388   incremental_got_plt_os->add_output_section_data(incr->got_plt_section());
2389
2390   // Add the .gnu_incremental_strtab section.
2391   const char* incremental_strtab_name =
2392     this->namepool_.add(".gnu_incremental_strtab", false, NULL);
2393   Output_section* incremental_strtab_os = this->make_output_section(incremental_strtab_name,
2394                                                         elfcpp::SHT_STRTAB, 0,
2395                                                         ORDER_INVALID, false);
2396   Output_data_strtab* strtab_data =
2397       new Output_data_strtab(incr->get_stringpool());
2398   incremental_strtab_os->add_output_section_data(strtab_data);
2399
2400   incremental_inputs_os->set_after_input_sections();
2401   incremental_symtab_os->set_after_input_sections();
2402   incremental_relocs_os->set_after_input_sections();
2403   incremental_got_plt_os->set_after_input_sections();
2404
2405   incremental_inputs_os->set_link_section(incremental_strtab_os);
2406   incremental_symtab_os->set_link_section(incremental_inputs_os);
2407   incremental_relocs_os->set_link_section(incremental_inputs_os);
2408   incremental_got_plt_os->set_link_section(incremental_inputs_os);
2409 }
2410
2411 // Return whether SEG1 should be before SEG2 in the output file.  This
2412 // is based entirely on the segment type and flags.  When this is
2413 // called the segment addresses has normally not yet been set.
2414
2415 bool
2416 Layout::segment_precedes(const Output_segment* seg1,
2417                          const Output_segment* seg2)
2418 {
2419   elfcpp::Elf_Word type1 = seg1->type();
2420   elfcpp::Elf_Word type2 = seg2->type();
2421
2422   // The single PT_PHDR segment is required to precede any loadable
2423   // segment.  We simply make it always first.
2424   if (type1 == elfcpp::PT_PHDR)
2425     {
2426       gold_assert(type2 != elfcpp::PT_PHDR);
2427       return true;
2428     }
2429   if (type2 == elfcpp::PT_PHDR)
2430     return false;
2431
2432   // The single PT_INTERP segment is required to precede any loadable
2433   // segment.  We simply make it always second.
2434   if (type1 == elfcpp::PT_INTERP)
2435     {
2436       gold_assert(type2 != elfcpp::PT_INTERP);
2437       return true;
2438     }
2439   if (type2 == elfcpp::PT_INTERP)
2440     return false;
2441
2442   // We then put PT_LOAD segments before any other segments.
2443   if (type1 == elfcpp::PT_LOAD && type2 != elfcpp::PT_LOAD)
2444     return true;
2445   if (type2 == elfcpp::PT_LOAD && type1 != elfcpp::PT_LOAD)
2446     return false;
2447
2448   // We put the PT_TLS segment last except for the PT_GNU_RELRO
2449   // segment, because that is where the dynamic linker expects to find
2450   // it (this is just for efficiency; other positions would also work
2451   // correctly).
2452   if (type1 == elfcpp::PT_TLS
2453       && type2 != elfcpp::PT_TLS
2454       && type2 != elfcpp::PT_GNU_RELRO)
2455     return false;
2456   if (type2 == elfcpp::PT_TLS
2457       && type1 != elfcpp::PT_TLS
2458       && type1 != elfcpp::PT_GNU_RELRO)
2459     return true;
2460
2461   // We put the PT_GNU_RELRO segment last, because that is where the
2462   // dynamic linker expects to find it (as with PT_TLS, this is just
2463   // for efficiency).
2464   if (type1 == elfcpp::PT_GNU_RELRO && type2 != elfcpp::PT_GNU_RELRO)
2465     return false;
2466   if (type2 == elfcpp::PT_GNU_RELRO && type1 != elfcpp::PT_GNU_RELRO)
2467     return true;
2468
2469   const elfcpp::Elf_Word flags1 = seg1->flags();
2470   const elfcpp::Elf_Word flags2 = seg2->flags();
2471
2472   // The order of non-PT_LOAD segments is unimportant.  We simply sort
2473   // by the numeric segment type and flags values.  There should not
2474   // be more than one segment with the same type and flags.
2475   if (type1 != elfcpp::PT_LOAD)
2476     {
2477       if (type1 != type2)
2478         return type1 < type2;
2479       gold_assert(flags1 != flags2);
2480       return flags1 < flags2;
2481     }
2482
2483   // If the addresses are set already, sort by load address.
2484   if (seg1->are_addresses_set())
2485     {
2486       if (!seg2->are_addresses_set())
2487         return true;
2488
2489       unsigned int section_count1 = seg1->output_section_count();
2490       unsigned int section_count2 = seg2->output_section_count();
2491       if (section_count1 == 0 && section_count2 > 0)
2492         return true;
2493       if (section_count1 > 0 && section_count2 == 0)
2494         return false;
2495
2496       uint64_t paddr1 = (seg1->are_addresses_set()
2497                          ? seg1->paddr()
2498                          : seg1->first_section_load_address());
2499       uint64_t paddr2 = (seg2->are_addresses_set()
2500                          ? seg2->paddr()
2501                          : seg2->first_section_load_address());
2502
2503       if (paddr1 != paddr2)
2504         return paddr1 < paddr2;
2505     }
2506   else if (seg2->are_addresses_set())
2507     return false;
2508
2509   // A segment which holds large data comes after a segment which does
2510   // not hold large data.
2511   if (seg1->is_large_data_segment())
2512     {
2513       if (!seg2->is_large_data_segment())
2514         return false;
2515     }
2516   else if (seg2->is_large_data_segment())
2517     return true;
2518
2519   // Otherwise, we sort PT_LOAD segments based on the flags.  Readonly
2520   // segments come before writable segments.  Then writable segments
2521   // with data come before writable segments without data.  Then
2522   // executable segments come before non-executable segments.  Then
2523   // the unlikely case of a non-readable segment comes before the
2524   // normal case of a readable segment.  If there are multiple
2525   // segments with the same type and flags, we require that the
2526   // address be set, and we sort by virtual address and then physical
2527   // address.
2528   if ((flags1 & elfcpp::PF_W) != (flags2 & elfcpp::PF_W))
2529     return (flags1 & elfcpp::PF_W) == 0;
2530   if ((flags1 & elfcpp::PF_W) != 0
2531       && seg1->has_any_data_sections() != seg2->has_any_data_sections())
2532     return seg1->has_any_data_sections();
2533   if ((flags1 & elfcpp::PF_X) != (flags2 & elfcpp::PF_X))
2534     return (flags1 & elfcpp::PF_X) != 0;
2535   if ((flags1 & elfcpp::PF_R) != (flags2 & elfcpp::PF_R))
2536     return (flags1 & elfcpp::PF_R) == 0;
2537
2538   // We shouldn't get here--we shouldn't create segments which we
2539   // can't distinguish.
2540   gold_unreachable();
2541 }
2542
2543 // Increase OFF so that it is congruent to ADDR modulo ABI_PAGESIZE.
2544
2545 static off_t
2546 align_file_offset(off_t off, uint64_t addr, uint64_t abi_pagesize)
2547 {
2548   uint64_t unsigned_off = off;
2549   uint64_t aligned_off = ((unsigned_off & ~(abi_pagesize - 1))
2550                           | (addr & (abi_pagesize - 1)));
2551   if (aligned_off < unsigned_off)
2552     aligned_off += abi_pagesize;
2553   return aligned_off;
2554 }
2555
2556 // Set the file offsets of all the segments, and all the sections they
2557 // contain.  They have all been created.  LOAD_SEG must be be laid out
2558 // first.  Return the offset of the data to follow.
2559
2560 off_t
2561 Layout::set_segment_offsets(const Target* target, Output_segment* load_seg,
2562                             unsigned int* pshndx)
2563 {
2564   // Sort them into the final order.
2565   std::sort(this->segment_list_.begin(), this->segment_list_.end(),
2566             Layout::Compare_segments());
2567
2568   // Find the PT_LOAD segments, and set their addresses and offsets
2569   // and their section's addresses and offsets.
2570   uint64_t addr;
2571   if (parameters->options().user_set_Ttext())
2572     addr = parameters->options().Ttext();
2573   else if (parameters->options().output_is_position_independent())
2574     addr = 0;
2575   else
2576     addr = target->default_text_segment_address();
2577   off_t off = 0;
2578
2579   // If LOAD_SEG is NULL, then the file header and segment headers
2580   // will not be loadable.  But they still need to be at offset 0 in
2581   // the file.  Set their offsets now.
2582   if (load_seg == NULL)
2583     {
2584       for (Data_list::iterator p = this->special_output_list_.begin();
2585            p != this->special_output_list_.end();
2586            ++p)
2587         {
2588           off = align_address(off, (*p)->addralign());
2589           (*p)->set_address_and_file_offset(0, off);
2590           off += (*p)->data_size();
2591         }
2592     }
2593
2594   unsigned int increase_relro = this->increase_relro_;
2595   if (this->script_options_->saw_sections_clause())
2596     increase_relro = 0;
2597
2598   const bool check_sections = parameters->options().check_sections();
2599   Output_segment* last_load_segment = NULL;
2600
2601   for (Segment_list::iterator p = this->segment_list_.begin();
2602        p != this->segment_list_.end();
2603        ++p)
2604     {
2605       if ((*p)->type() == elfcpp::PT_LOAD)
2606         {
2607           if (load_seg != NULL && load_seg != *p)
2608             gold_unreachable();
2609           load_seg = NULL;
2610
2611           bool are_addresses_set = (*p)->are_addresses_set();
2612           if (are_addresses_set)
2613             {
2614               // When it comes to setting file offsets, we care about
2615               // the physical address.
2616               addr = (*p)->paddr();
2617             }
2618           else if (parameters->options().user_set_Tdata()
2619                    && ((*p)->flags() & elfcpp::PF_W) != 0
2620                    && (!parameters->options().user_set_Tbss()
2621                        || (*p)->has_any_data_sections()))
2622             {
2623               addr = parameters->options().Tdata();
2624               are_addresses_set = true;
2625             }
2626           else if (parameters->options().user_set_Tbss()
2627                    && ((*p)->flags() & elfcpp::PF_W) != 0
2628                    && !(*p)->has_any_data_sections())
2629             {
2630               addr = parameters->options().Tbss();
2631               are_addresses_set = true;
2632             }
2633
2634           uint64_t orig_addr = addr;
2635           uint64_t orig_off = off;
2636
2637           uint64_t aligned_addr = 0;
2638           uint64_t abi_pagesize = target->abi_pagesize();
2639           uint64_t common_pagesize = target->common_pagesize();
2640
2641           if (!parameters->options().nmagic()
2642               && !parameters->options().omagic())
2643             (*p)->set_minimum_p_align(common_pagesize);
2644
2645           if (!are_addresses_set)
2646             {
2647               // Skip the address forward one page, maintaining the same
2648               // position within the page.  This lets us store both segments
2649               // overlapping on a single page in the file, but the loader will
2650               // put them on different pages in memory. We will revisit this
2651               // decision once we know the size of the segment.
2652
2653               addr = align_address(addr, (*p)->maximum_alignment());
2654               aligned_addr = addr;
2655
2656               if ((addr & (abi_pagesize - 1)) != 0)
2657                 addr = addr + abi_pagesize;
2658
2659               off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
2660             }
2661
2662           if (!parameters->options().nmagic()
2663               && !parameters->options().omagic())
2664             off = align_file_offset(off, addr, abi_pagesize);
2665           else if (load_seg == NULL)
2666             {
2667               // This is -N or -n with a section script which prevents
2668               // us from using a load segment.  We need to ensure that
2669               // the file offset is aligned to the alignment of the
2670               // segment.  This is because the linker script
2671               // implicitly assumed a zero offset.  If we don't align
2672               // here, then the alignment of the sections in the
2673               // linker script may not match the alignment of the
2674               // sections in the set_section_addresses call below,
2675               // causing an error about dot moving backward.
2676               off = align_address(off, (*p)->maximum_alignment());
2677             }
2678
2679           unsigned int shndx_hold = *pshndx;
2680           bool has_relro = false;
2681           uint64_t new_addr = (*p)->set_section_addresses(this, false, addr,
2682                                                           &increase_relro,
2683                                                           &has_relro,
2684                                                           &off, pshndx);
2685
2686           // Now that we know the size of this segment, we may be able
2687           // to save a page in memory, at the cost of wasting some
2688           // file space, by instead aligning to the start of a new
2689           // page.  Here we use the real machine page size rather than
2690           // the ABI mandated page size.  If the segment has been
2691           // aligned so that the relro data ends at a page boundary,
2692           // we do not try to realign it.
2693
2694           if (!are_addresses_set && !has_relro && aligned_addr != addr)
2695             {
2696               uint64_t first_off = (common_pagesize
2697                                     - (aligned_addr
2698                                        & (common_pagesize - 1)));
2699               uint64_t last_off = new_addr & (common_pagesize - 1);
2700               if (first_off > 0
2701                   && last_off > 0
2702                   && ((aligned_addr & ~ (common_pagesize - 1))
2703                       != (new_addr & ~ (common_pagesize - 1)))
2704                   && first_off + last_off <= common_pagesize)
2705                 {
2706                   *pshndx = shndx_hold;
2707                   addr = align_address(aligned_addr, common_pagesize);
2708                   addr = align_address(addr, (*p)->maximum_alignment());
2709                   off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
2710                   off = align_file_offset(off, addr, abi_pagesize);
2711
2712                   increase_relro = this->increase_relro_;
2713                   if (this->script_options_->saw_sections_clause())
2714                     increase_relro = 0;
2715                   has_relro = false;
2716
2717                   new_addr = (*p)->set_section_addresses(this, true, addr,
2718                                                          &increase_relro,
2719                                                          &has_relro,
2720                                                          &off, pshndx);
2721                 }
2722             }
2723
2724           addr = new_addr;
2725
2726           // Implement --check-sections.  We know that the segments
2727           // are sorted by LMA.
2728           if (check_sections && last_load_segment != NULL)
2729             {
2730               gold_assert(last_load_segment->paddr() <= (*p)->paddr());
2731               if (last_load_segment->paddr() + last_load_segment->memsz()
2732                   > (*p)->paddr())
2733                 {
2734                   unsigned long long lb1 = last_load_segment->paddr();
2735                   unsigned long long le1 = lb1 + last_load_segment->memsz();
2736                   unsigned long long lb2 = (*p)->paddr();
2737                   unsigned long long le2 = lb2 + (*p)->memsz();
2738                   gold_error(_("load segment overlap [0x%llx -> 0x%llx] and "
2739                                "[0x%llx -> 0x%llx]"),
2740                              lb1, le1, lb2, le2);
2741                 }
2742             }
2743           last_load_segment = *p;
2744         }
2745     }
2746
2747   // Handle the non-PT_LOAD segments, setting their offsets from their
2748   // section's offsets.
2749   for (Segment_list::iterator p = this->segment_list_.begin();
2750        p != this->segment_list_.end();
2751        ++p)
2752     {
2753       if ((*p)->type() != elfcpp::PT_LOAD)
2754         (*p)->set_offset((*p)->type() == elfcpp::PT_GNU_RELRO
2755                          ? increase_relro
2756                          : 0);
2757     }
2758
2759   // Set the TLS offsets for each section in the PT_TLS segment.
2760   if (this->tls_segment_ != NULL)
2761     this->tls_segment_->set_tls_offsets();
2762
2763   return off;
2764 }
2765
2766 // Set the offsets of all the allocated sections when doing a
2767 // relocatable link.  This does the same jobs as set_segment_offsets,
2768 // only for a relocatable link.
2769
2770 off_t
2771 Layout::set_relocatable_section_offsets(Output_data* file_header,
2772                                         unsigned int* pshndx)
2773 {
2774   off_t off = 0;
2775
2776   file_header->set_address_and_file_offset(0, 0);
2777   off += file_header->data_size();
2778
2779   for (Section_list::iterator p = this->section_list_.begin();
2780        p != this->section_list_.end();
2781        ++p)
2782     {
2783       // We skip unallocated sections here, except that group sections
2784       // have to come first.
2785       if (((*p)->flags() & elfcpp::SHF_ALLOC) == 0
2786           && (*p)->type() != elfcpp::SHT_GROUP)
2787         continue;
2788
2789       off = align_address(off, (*p)->addralign());
2790
2791       // The linker script might have set the address.
2792       if (!(*p)->is_address_valid())
2793         (*p)->set_address(0);
2794       (*p)->set_file_offset(off);
2795       (*p)->finalize_data_size();
2796       off += (*p)->data_size();
2797
2798       (*p)->set_out_shndx(*pshndx);
2799       ++*pshndx;
2800     }
2801
2802   return off;
2803 }
2804
2805 // Set the file offset of all the sections not associated with a
2806 // segment.
2807
2808 off_t
2809 Layout::set_section_offsets(off_t off, Layout::Section_offset_pass pass)
2810 {
2811   for (Section_list::iterator p = this->unattached_section_list_.begin();
2812        p != this->unattached_section_list_.end();
2813        ++p)
2814     {
2815       // The symtab section is handled in create_symtab_sections.
2816       if (*p == this->symtab_section_)
2817         continue;
2818
2819       // If we've already set the data size, don't set it again.
2820       if ((*p)->is_offset_valid() && (*p)->is_data_size_valid())
2821         continue;
2822
2823       if (pass == BEFORE_INPUT_SECTIONS_PASS
2824           && (*p)->requires_postprocessing())
2825         {
2826           (*p)->create_postprocessing_buffer();
2827           this->any_postprocessing_sections_ = true;
2828         }
2829
2830       if (pass == BEFORE_INPUT_SECTIONS_PASS
2831           && (*p)->after_input_sections())
2832         continue;
2833       else if (pass == POSTPROCESSING_SECTIONS_PASS
2834                && (!(*p)->after_input_sections()
2835                    || (*p)->type() == elfcpp::SHT_STRTAB))
2836         continue;
2837       else if (pass == STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
2838                && (!(*p)->after_input_sections()
2839                    || (*p)->type() != elfcpp::SHT_STRTAB))
2840         continue;
2841
2842       off = align_address(off, (*p)->addralign());
2843       (*p)->set_file_offset(off);
2844       (*p)->finalize_data_size();
2845       off += (*p)->data_size();
2846
2847       // At this point the name must be set.
2848       if (pass != STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS)
2849         this->namepool_.add((*p)->name(), false, NULL);
2850     }
2851   return off;
2852 }
2853
2854 // Set the section indexes of all the sections not associated with a
2855 // segment.
2856
2857 unsigned int
2858 Layout::set_section_indexes(unsigned int shndx)
2859 {
2860   for (Section_list::iterator p = this->unattached_section_list_.begin();
2861        p != this->unattached_section_list_.end();
2862        ++p)
2863     {
2864       if (!(*p)->has_out_shndx())
2865         {
2866           (*p)->set_out_shndx(shndx);
2867           ++shndx;
2868         }
2869     }
2870   return shndx;
2871 }
2872
2873 // Set the section addresses according to the linker script.  This is
2874 // only called when we see a SECTIONS clause.  This returns the
2875 // program segment which should hold the file header and segment
2876 // headers, if any.  It will return NULL if they should not be in a
2877 // segment.
2878
2879 Output_segment*
2880 Layout::set_section_addresses_from_script(Symbol_table* symtab)
2881 {
2882   Script_sections* ss = this->script_options_->script_sections();
2883   gold_assert(ss->saw_sections_clause());
2884   return this->script_options_->set_section_addresses(symtab, this);
2885 }
2886
2887 // Place the orphan sections in the linker script.
2888
2889 void
2890 Layout::place_orphan_sections_in_script()
2891 {
2892   Script_sections* ss = this->script_options_->script_sections();
2893   gold_assert(ss->saw_sections_clause());
2894
2895   // Place each orphaned output section in the script.
2896   for (Section_list::iterator p = this->section_list_.begin();
2897        p != this->section_list_.end();
2898        ++p)
2899     {
2900       if (!(*p)->found_in_sections_clause())
2901         ss->place_orphan(*p);
2902     }
2903 }
2904
2905 // Count the local symbols in the regular symbol table and the dynamic
2906 // symbol table, and build the respective string pools.
2907
2908 void
2909 Layout::count_local_symbols(const Task* task,
2910                             const Input_objects* input_objects)
2911 {
2912   // First, figure out an upper bound on the number of symbols we'll
2913   // be inserting into each pool.  This helps us create the pools with
2914   // the right size, to avoid unnecessary hashtable resizing.
2915   unsigned int symbol_count = 0;
2916   for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
2917        p != input_objects->relobj_end();
2918        ++p)
2919     symbol_count += (*p)->local_symbol_count();
2920
2921   // Go from "upper bound" to "estimate."  We overcount for two
2922   // reasons: we double-count symbols that occur in more than one
2923   // object file, and we count symbols that are dropped from the
2924   // output.  Add it all together and assume we overcount by 100%.
2925   symbol_count /= 2;
2926
2927   // We assume all symbols will go into both the sympool and dynpool.
2928   this->sympool_.reserve(symbol_count);
2929   this->dynpool_.reserve(symbol_count);
2930
2931   for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
2932        p != input_objects->relobj_end();
2933        ++p)
2934     {
2935       Task_lock_obj<Object> tlo(task, *p);
2936       (*p)->count_local_symbols(&this->sympool_, &this->dynpool_);
2937     }
2938 }
2939
2940 // Create the symbol table sections.  Here we also set the final
2941 // values of the symbols.  At this point all the loadable sections are
2942 // fully laid out.  SHNUM is the number of sections so far.
2943
2944 void
2945 Layout::create_symtab_sections(const Input_objects* input_objects,
2946                                Symbol_table* symtab,
2947                                unsigned int shnum,
2948                                off_t* poff)
2949 {
2950   int symsize;
2951   unsigned int align;
2952   if (parameters->target().get_size() == 32)
2953     {
2954       symsize = elfcpp::Elf_sizes<32>::sym_size;
2955       align = 4;
2956     }
2957   else if (parameters->target().get_size() == 64)
2958     {
2959       symsize = elfcpp::Elf_sizes<64>::sym_size;
2960       align = 8;
2961     }
2962   else
2963     gold_unreachable();
2964
2965   off_t off = *poff;
2966   off = align_address(off, align);
2967   off_t startoff = off;
2968
2969   // Save space for the dummy symbol at the start of the section.  We
2970   // never bother to write this out--it will just be left as zero.
2971   off += symsize;
2972   unsigned int local_symbol_index = 1;
2973
2974   // Add STT_SECTION symbols for each Output section which needs one.
2975   for (Section_list::iterator p = this->section_list_.begin();
2976        p != this->section_list_.end();
2977        ++p)
2978     {
2979       if (!(*p)->needs_symtab_index())
2980         (*p)->set_symtab_index(-1U);
2981       else
2982         {
2983           (*p)->set_symtab_index(local_symbol_index);
2984           ++local_symbol_index;
2985           off += symsize;
2986         }
2987     }
2988
2989   for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
2990        p != input_objects->relobj_end();
2991        ++p)
2992     {
2993       unsigned int index = (*p)->finalize_local_symbols(local_symbol_index,
2994                                                         off, symtab);
2995       off += (index - local_symbol_index) * symsize;
2996       local_symbol_index = index;
2997     }
2998
2999   unsigned int local_symcount = local_symbol_index;
3000   gold_assert(static_cast<off_t>(local_symcount * symsize) == off - startoff);
3001
3002   off_t dynoff;
3003   size_t dyn_global_index;
3004   size_t dyncount;
3005   if (this->dynsym_section_ == NULL)
3006     {
3007       dynoff = 0;
3008       dyn_global_index = 0;
3009       dyncount = 0;
3010     }
3011   else
3012     {
3013       dyn_global_index = this->dynsym_section_->info();
3014       off_t locsize = dyn_global_index * this->dynsym_section_->entsize();
3015       dynoff = this->dynsym_section_->offset() + locsize;
3016       dyncount = (this->dynsym_section_->data_size() - locsize) / symsize;
3017       gold_assert(static_cast<off_t>(dyncount * symsize)
3018                   == this->dynsym_section_->data_size() - locsize);
3019     }
3020
3021   off = symtab->finalize(off, dynoff, dyn_global_index, dyncount,
3022                          &this->sympool_, &local_symcount);
3023
3024   if (!parameters->options().strip_all())
3025     {
3026       this->sympool_.set_string_offsets();
3027
3028       const char* symtab_name = this->namepool_.add(".symtab", false, NULL);
3029       Output_section* osymtab = this->make_output_section(symtab_name,
3030                                                           elfcpp::SHT_SYMTAB,
3031                                                           0, ORDER_INVALID,
3032                                                           false);
3033       this->symtab_section_ = osymtab;
3034
3035       Output_section_data* pos = new Output_data_fixed_space(off - startoff,
3036                                                              align,
3037                                                              "** symtab");
3038       osymtab->add_output_section_data(pos);
3039
3040       // We generate a .symtab_shndx section if we have more than
3041       // SHN_LORESERVE sections.  Technically it is possible that we
3042       // don't need one, because it is possible that there are no
3043       // symbols in any of sections with indexes larger than
3044       // SHN_LORESERVE.  That is probably unusual, though, and it is
3045       // easier to always create one than to compute section indexes
3046       // twice (once here, once when writing out the symbols).
3047       if (shnum >= elfcpp::SHN_LORESERVE)
3048         {
3049           const char* symtab_xindex_name = this->namepool_.add(".symtab_shndx",
3050                                                                false, NULL);
3051           Output_section* osymtab_xindex =
3052             this->make_output_section(symtab_xindex_name,
3053                                       elfcpp::SHT_SYMTAB_SHNDX, 0,
3054                                       ORDER_INVALID, false);
3055
3056           size_t symcount = (off - startoff) / symsize;
3057           this->symtab_xindex_ = new Output_symtab_xindex(symcount);
3058
3059           osymtab_xindex->add_output_section_data(this->symtab_xindex_);
3060
3061           osymtab_xindex->set_link_section(osymtab);
3062           osymtab_xindex->set_addralign(4);
3063           osymtab_xindex->set_entsize(4);
3064
3065           osymtab_xindex->set_after_input_sections();
3066
3067           // This tells the driver code to wait until the symbol table
3068           // has written out before writing out the postprocessing
3069           // sections, including the .symtab_shndx section.
3070           this->any_postprocessing_sections_ = true;
3071         }
3072
3073       const char* strtab_name = this->namepool_.add(".strtab", false, NULL);
3074       Output_section* ostrtab = this->make_output_section(strtab_name,
3075                                                           elfcpp::SHT_STRTAB,
3076                                                           0, ORDER_INVALID,
3077                                                           false);
3078
3079       Output_section_data* pstr = new Output_data_strtab(&this->sympool_);
3080       ostrtab->add_output_section_data(pstr);
3081
3082       osymtab->set_file_offset(startoff);
3083       osymtab->finalize_data_size();
3084       osymtab->set_link_section(ostrtab);
3085       osymtab->set_info(local_symcount);
3086       osymtab->set_entsize(symsize);
3087
3088       *poff = off;
3089     }
3090 }
3091
3092 // Create the .shstrtab section, which holds the names of the
3093 // sections.  At the time this is called, we have created all the
3094 // output sections except .shstrtab itself.
3095
3096 Output_section*
3097 Layout::create_shstrtab()
3098 {
3099   // FIXME: We don't need to create a .shstrtab section if we are
3100   // stripping everything.
3101
3102   const char* name = this->namepool_.add(".shstrtab", false, NULL);
3103
3104   Output_section* os = this->make_output_section(name, elfcpp::SHT_STRTAB, 0,
3105                                                  ORDER_INVALID, false);
3106
3107   if (strcmp(parameters->options().compress_debug_sections(), "none") != 0)
3108     {
3109       // We can't write out this section until we've set all the
3110       // section names, and we don't set the names of compressed
3111       // output sections until relocations are complete.  FIXME: With
3112       // the current names we use, this is unnecessary.
3113       os->set_after_input_sections();
3114     }
3115
3116   Output_section_data* posd = new Output_data_strtab(&this->namepool_);
3117   os->add_output_section_data(posd);
3118
3119   return os;
3120 }
3121
3122 // Create the section headers.  SIZE is 32 or 64.  OFF is the file
3123 // offset.
3124
3125 void
3126 Layout::create_shdrs(const Output_section* shstrtab_section, off_t* poff)
3127 {
3128   Output_section_headers* oshdrs;
3129   oshdrs = new Output_section_headers(this,
3130                                       &this->segment_list_,
3131                                       &this->section_list_,
3132                                       &this->unattached_section_list_,
3133                                       &this->namepool_,
3134                                       shstrtab_section);
3135   off_t off = align_address(*poff, oshdrs->addralign());
3136   oshdrs->set_address_and_file_offset(0, off);
3137   off += oshdrs->data_size();
3138   *poff = off;
3139   this->section_headers_ = oshdrs;
3140 }
3141
3142 // Count the allocated sections.
3143
3144 size_t
3145 Layout::allocated_output_section_count() const
3146 {
3147   size_t section_count = 0;
3148   for (Segment_list::const_iterator p = this->segment_list_.begin();
3149        p != this->segment_list_.end();
3150        ++p)
3151     section_count += (*p)->output_section_count();
3152   return section_count;
3153 }
3154
3155 // Create the dynamic symbol table.
3156
3157 void
3158 Layout::create_dynamic_symtab(const Input_objects* input_objects,
3159                               Symbol_table* symtab,
3160                               Output_section** pdynstr,
3161                               unsigned int* plocal_dynamic_count,
3162                               std::vector<Symbol*>* pdynamic_symbols,
3163                               Versions* pversions)
3164 {
3165   // Count all the symbols in the dynamic symbol table, and set the
3166   // dynamic symbol indexes.
3167
3168   // Skip symbol 0, which is always all zeroes.
3169   unsigned int index = 1;
3170
3171   // Add STT_SECTION symbols for each Output section which needs one.
3172   for (Section_list::iterator p = this->section_list_.begin();
3173        p != this->section_list_.end();
3174        ++p)
3175     {
3176       if (!(*p)->needs_dynsym_index())
3177         (*p)->set_dynsym_index(-1U);
3178       else
3179         {
3180           (*p)->set_dynsym_index(index);
3181           ++index;
3182         }
3183     }
3184
3185   // Count the local symbols that need to go in the dynamic symbol table,
3186   // and set the dynamic symbol indexes.
3187   for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
3188        p != input_objects->relobj_end();
3189        ++p)
3190     {
3191       unsigned int new_index = (*p)->set_local_dynsym_indexes(index);
3192       index = new_index;
3193     }
3194
3195   unsigned int local_symcount = index;
3196   *plocal_dynamic_count = local_symcount;
3197
3198   index = symtab->set_dynsym_indexes(index, pdynamic_symbols,
3199                                      &this->dynpool_, pversions);
3200
3201   int symsize;
3202   unsigned int align;
3203   const int size = parameters->target().get_size();
3204   if (size == 32)
3205     {
3206       symsize = elfcpp::Elf_sizes<32>::sym_size;
3207       align = 4;
3208     }
3209   else if (size == 64)
3210     {
3211       symsize = elfcpp::Elf_sizes<64>::sym_size;
3212       align = 8;
3213     }
3214   else
3215     gold_unreachable();
3216
3217   // Create the dynamic symbol table section.
3218
3219   Output_section* dynsym = this->choose_output_section(NULL, ".dynsym",
3220                                                        elfcpp::SHT_DYNSYM,
3221                                                        elfcpp::SHF_ALLOC,
3222                                                        false,
3223                                                        ORDER_DYNAMIC_LINKER,
3224                                                        false);
3225
3226   Output_section_data* odata = new Output_data_fixed_space(index * symsize,
3227                                                            align,
3228                                                            "** dynsym");
3229   dynsym->add_output_section_data(odata);
3230
3231   dynsym->set_info(local_symcount);
3232   dynsym->set_entsize(symsize);
3233   dynsym->set_addralign(align);
3234
3235   this->dynsym_section_ = dynsym;
3236
3237   Output_data_dynamic* const odyn = this->dynamic_data_;
3238   odyn->add_section_address(elfcpp::DT_SYMTAB, dynsym);
3239   odyn->add_constant(elfcpp::DT_SYMENT, symsize);
3240
3241   // If there are more than SHN_LORESERVE allocated sections, we
3242   // create a .dynsym_shndx section.  It is possible that we don't
3243   // need one, because it is possible that there are no dynamic
3244   // symbols in any of the sections with indexes larger than
3245   // SHN_LORESERVE.  This is probably unusual, though, and at this
3246   // time we don't know the actual section indexes so it is
3247   // inconvenient to check.
3248   if (this->allocated_output_section_count() >= elfcpp::SHN_LORESERVE)
3249     {
3250       Output_section* dynsym_xindex =
3251         this->choose_output_section(NULL, ".dynsym_shndx",
3252                                     elfcpp::SHT_SYMTAB_SHNDX,
3253                                     elfcpp::SHF_ALLOC,
3254                                     false, ORDER_DYNAMIC_LINKER, false);
3255
3256       this->dynsym_xindex_ = new Output_symtab_xindex(index);
3257
3258       dynsym_xindex->add_output_section_data(this->dynsym_xindex_);
3259
3260       dynsym_xindex->set_link_section(dynsym);
3261       dynsym_xindex->set_addralign(4);
3262       dynsym_xindex->set_entsize(4);
3263
3264       dynsym_xindex->set_after_input_sections();
3265
3266       // This tells the driver code to wait until the symbol table has
3267       // written out before writing out the postprocessing sections,
3268       // including the .dynsym_shndx section.
3269       this->any_postprocessing_sections_ = true;
3270     }
3271
3272   // Create the dynamic string table section.
3273
3274   Output_section* dynstr = this->choose_output_section(NULL, ".dynstr",
3275                                                        elfcpp::SHT_STRTAB,
3276                                                        elfcpp::SHF_ALLOC,
3277                                                        false,
3278                                                        ORDER_DYNAMIC_LINKER,
3279                                                        false);
3280
3281   Output_section_data* strdata = new Output_data_strtab(&this->dynpool_);
3282   dynstr->add_output_section_data(strdata);
3283
3284   dynsym->set_link_section(dynstr);
3285   this->dynamic_section_->set_link_section(dynstr);
3286
3287   odyn->add_section_address(elfcpp::DT_STRTAB, dynstr);
3288   odyn->add_section_size(elfcpp::DT_STRSZ, dynstr);
3289
3290   *pdynstr = dynstr;
3291
3292   // Create the hash tables.
3293
3294   if (strcmp(parameters->options().hash_style(), "sysv") == 0
3295       || strcmp(parameters->options().hash_style(), "both") == 0)
3296     {
3297       unsigned char* phash;
3298       unsigned int hashlen;
3299       Dynobj::create_elf_hash_table(*pdynamic_symbols, local_symcount,
3300                                     &phash, &hashlen);
3301
3302       Output_section* hashsec =
3303         this->choose_output_section(NULL, ".hash", elfcpp::SHT_HASH,
3304                                     elfcpp::SHF_ALLOC, false,
3305                                     ORDER_DYNAMIC_LINKER, false);
3306
3307       Output_section_data* hashdata = new Output_data_const_buffer(phash,
3308                                                                    hashlen,
3309                                                                    align,
3310                                                                    "** hash");
3311       hashsec->add_output_section_data(hashdata);
3312
3313       hashsec->set_link_section(dynsym);
3314       hashsec->set_entsize(4);
3315
3316       odyn->add_section_address(elfcpp::DT_HASH, hashsec);
3317     }
3318
3319   if (strcmp(parameters->options().hash_style(), "gnu") == 0
3320       || strcmp(parameters->options().hash_style(), "both") == 0)
3321     {
3322       unsigned char* phash;
3323       unsigned int hashlen;
3324       Dynobj::create_gnu_hash_table(*pdynamic_symbols, local_symcount,
3325                                     &phash, &hashlen);
3326
3327       Output_section* hashsec =
3328         this->choose_output_section(NULL, ".gnu.hash", elfcpp::SHT_GNU_HASH,
3329                                     elfcpp::SHF_ALLOC, false,
3330                                     ORDER_DYNAMIC_LINKER, false);
3331
3332       Output_section_data* hashdata = new Output_data_const_buffer(phash,
3333                                                                    hashlen,
3334                                                                    align,
3335                                                                    "** hash");
3336       hashsec->add_output_section_data(hashdata);
3337
3338       hashsec->set_link_section(dynsym);
3339
3340       // For a 64-bit target, the entries in .gnu.hash do not have a
3341       // uniform size, so we only set the entry size for a 32-bit
3342       // target.
3343       if (parameters->target().get_size() == 32)
3344         hashsec->set_entsize(4);
3345
3346       odyn->add_section_address(elfcpp::DT_GNU_HASH, hashsec);
3347     }
3348 }
3349
3350 // Assign offsets to each local portion of the dynamic symbol table.
3351
3352 void
3353 Layout::assign_local_dynsym_offsets(const Input_objects* input_objects)
3354 {
3355   Output_section* dynsym = this->dynsym_section_;
3356   gold_assert(dynsym != NULL);
3357
3358   off_t off = dynsym->offset();
3359
3360   // Skip the dummy symbol at the start of the section.
3361   off += dynsym->entsize();
3362
3363   for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
3364        p != input_objects->relobj_end();
3365        ++p)
3366     {
3367       unsigned int count = (*p)->set_local_dynsym_offset(off);
3368       off += count * dynsym->entsize();
3369     }
3370 }
3371
3372 // Create the version sections.
3373
3374 void
3375 Layout::create_version_sections(const Versions* versions,
3376                                 const Symbol_table* symtab,
3377                                 unsigned int local_symcount,
3378                                 const std::vector<Symbol*>& dynamic_symbols,
3379                                 const Output_section* dynstr)
3380 {
3381   if (!versions->any_defs() && !versions->any_needs())
3382     return;
3383
3384   switch (parameters->size_and_endianness())
3385     {
3386 #ifdef HAVE_TARGET_32_LITTLE
3387     case Parameters::TARGET_32_LITTLE:
3388       this->sized_create_version_sections<32, false>(versions, symtab,
3389                                                      local_symcount,
3390                                                      dynamic_symbols, dynstr);
3391       break;
3392 #endif
3393 #ifdef HAVE_TARGET_32_BIG
3394     case Parameters::TARGET_32_BIG:
3395       this->sized_create_version_sections<32, true>(versions, symtab,
3396                                                     local_symcount,
3397                                                     dynamic_symbols, dynstr);
3398       break;
3399 #endif
3400 #ifdef HAVE_TARGET_64_LITTLE
3401     case Parameters::TARGET_64_LITTLE:
3402       this->sized_create_version_sections<64, false>(versions, symtab,
3403                                                      local_symcount,
3404                                                      dynamic_symbols, dynstr);
3405       break;
3406 #endif
3407 #ifdef HAVE_TARGET_64_BIG
3408     case Parameters::TARGET_64_BIG:
3409       this->sized_create_version_sections<64, true>(versions, symtab,
3410                                                     local_symcount,
3411                                                     dynamic_symbols, dynstr);
3412       break;
3413 #endif
3414     default:
3415       gold_unreachable();
3416     }
3417 }
3418
3419 // Create the version sections, sized version.
3420
3421 template<int size, bool big_endian>
3422 void
3423 Layout::sized_create_version_sections(
3424     const Versions* versions,
3425     const Symbol_table* symtab,
3426     unsigned int local_symcount,
3427     const std::vector<Symbol*>& dynamic_symbols,
3428     const Output_section* dynstr)
3429 {
3430   Output_section* vsec = this->choose_output_section(NULL, ".gnu.version",
3431                                                      elfcpp::SHT_GNU_versym,
3432                                                      elfcpp::SHF_ALLOC,
3433                                                      false,
3434                                                      ORDER_DYNAMIC_LINKER,
3435                                                      false);
3436
3437   unsigned char* vbuf;
3438   unsigned int vsize;
3439   versions->symbol_section_contents<size, big_endian>(symtab, &this->dynpool_,
3440                                                       local_symcount,
3441                                                       dynamic_symbols,
3442                                                       &vbuf, &vsize);
3443
3444   Output_section_data* vdata = new Output_data_const_buffer(vbuf, vsize, 2,
3445                                                             "** versions");
3446
3447   vsec->add_output_section_data(vdata);
3448   vsec->set_entsize(2);
3449   vsec->set_link_section(this->dynsym_section_);
3450
3451   Output_data_dynamic* const odyn = this->dynamic_data_;
3452   odyn->add_section_address(elfcpp::DT_VERSYM, vsec);
3453
3454   if (versions->any_defs())
3455     {
3456       Output_section* vdsec;
3457       vdsec= this->choose_output_section(NULL, ".gnu.version_d",
3458                                          elfcpp::SHT_GNU_verdef,
3459                                          elfcpp::SHF_ALLOC,
3460                                          false, ORDER_DYNAMIC_LINKER, false);
3461
3462       unsigned char* vdbuf;
3463       unsigned int vdsize;
3464       unsigned int vdentries;
3465       versions->def_section_contents<size, big_endian>(&this->dynpool_, &vdbuf,
3466                                                        &vdsize, &vdentries);
3467
3468       Output_section_data* vddata =
3469         new Output_data_const_buffer(vdbuf, vdsize, 4, "** version defs");
3470
3471       vdsec->add_output_section_data(vddata);
3472       vdsec->set_link_section(dynstr);
3473       vdsec->set_info(vdentries);
3474
3475       odyn->add_section_address(elfcpp::DT_VERDEF, vdsec);
3476       odyn->add_constant(elfcpp::DT_VERDEFNUM, vdentries);
3477     }
3478
3479   if (versions->any_needs())
3480     {
3481       Output_section* vnsec;
3482       vnsec = this->choose_output_section(NULL, ".gnu.version_r",
3483                                           elfcpp::SHT_GNU_verneed,
3484                                           elfcpp::SHF_ALLOC,
3485                                           false, ORDER_DYNAMIC_LINKER, false);
3486
3487       unsigned char* vnbuf;
3488       unsigned int vnsize;
3489       unsigned int vnentries;
3490       versions->need_section_contents<size, big_endian>(&this->dynpool_,
3491                                                         &vnbuf, &vnsize,
3492                                                         &vnentries);
3493
3494       Output_section_data* vndata =
3495         new Output_data_const_buffer(vnbuf, vnsize, 4, "** version refs");
3496
3497       vnsec->add_output_section_data(vndata);
3498       vnsec->set_link_section(dynstr);
3499       vnsec->set_info(vnentries);
3500
3501       odyn->add_section_address(elfcpp::DT_VERNEED, vnsec);
3502       odyn->add_constant(elfcpp::DT_VERNEEDNUM, vnentries);
3503     }
3504 }
3505
3506 // Create the .interp section and PT_INTERP segment.
3507
3508 void
3509 Layout::create_interp(const Target* target)
3510 {
3511   const char* interp = parameters->options().dynamic_linker();
3512   if (interp == NULL)
3513     {
3514       interp = target->dynamic_linker();
3515       gold_assert(interp != NULL);
3516     }
3517
3518   size_t len = strlen(interp) + 1;
3519
3520   Output_section_data* odata = new Output_data_const(interp, len, 1);
3521
3522   Output_section* osec = this->choose_output_section(NULL, ".interp",
3523                                                      elfcpp::SHT_PROGBITS,
3524                                                      elfcpp::SHF_ALLOC,
3525                                                      false, ORDER_INTERP,
3526                                                      false);
3527   osec->add_output_section_data(odata);
3528
3529   if (!this->script_options_->saw_phdrs_clause())
3530     {
3531       Output_segment* oseg = this->make_output_segment(elfcpp::PT_INTERP,
3532                                                        elfcpp::PF_R);
3533       oseg->add_output_section_to_nonload(osec, elfcpp::PF_R);
3534     }
3535 }
3536
3537 // Add dynamic tags for the PLT and the dynamic relocs.  This is
3538 // called by the target-specific code.  This does nothing if not doing
3539 // a dynamic link.
3540
3541 // USE_REL is true for REL relocs rather than RELA relocs.
3542
3543 // If PLT_GOT is not NULL, then DT_PLTGOT points to it.
3544
3545 // If PLT_REL is not NULL, it is used for DT_PLTRELSZ, and DT_JMPREL,
3546 // and we also set DT_PLTREL.  We use PLT_REL's output section, since
3547 // some targets have multiple reloc sections in PLT_REL.
3548
3549 // If DYN_REL is not NULL, it is used for DT_REL/DT_RELA,
3550 // DT_RELSZ/DT_RELASZ, DT_RELENT/DT_RELAENT.
3551
3552 // If ADD_DEBUG is true, we add a DT_DEBUG entry when generating an
3553 // executable.
3554
3555 void
3556 Layout::add_target_dynamic_tags(bool use_rel, const Output_data* plt_got,
3557                                 const Output_data* plt_rel,
3558                                 const Output_data_reloc_generic* dyn_rel,
3559                                 bool add_debug, bool dynrel_includes_plt)
3560 {
3561   Output_data_dynamic* odyn = this->dynamic_data_;
3562   if (odyn == NULL)
3563     return;
3564
3565   if (plt_got != NULL && plt_got->output_section() != NULL)
3566     odyn->add_section_address(elfcpp::DT_PLTGOT, plt_got);
3567
3568   if (plt_rel != NULL && plt_rel->output_section() != NULL)
3569     {
3570       odyn->add_section_size(elfcpp::DT_PLTRELSZ, plt_rel->output_section());
3571       odyn->add_section_address(elfcpp::DT_JMPREL, plt_rel->output_section());
3572       odyn->add_constant(elfcpp::DT_PLTREL,
3573                          use_rel ? elfcpp::DT_REL : elfcpp::DT_RELA);
3574     }
3575
3576   if (dyn_rel != NULL && dyn_rel->output_section() != NULL)
3577     {
3578       odyn->add_section_address(use_rel ? elfcpp::DT_REL : elfcpp::DT_RELA,
3579                                 dyn_rel);
3580       if (plt_rel != NULL && dynrel_includes_plt)
3581         odyn->add_section_size(use_rel ? elfcpp::DT_RELSZ : elfcpp::DT_RELASZ,
3582                                dyn_rel, plt_rel);
3583       else
3584         odyn->add_section_size(use_rel ? elfcpp::DT_RELSZ : elfcpp::DT_RELASZ,
3585                                dyn_rel);
3586       const int size = parameters->target().get_size();
3587       elfcpp::DT rel_tag;
3588       int rel_size;
3589       if (use_rel)
3590         {
3591           rel_tag = elfcpp::DT_RELENT;
3592           if (size == 32)
3593             rel_size = Reloc_types<elfcpp::SHT_REL, 32, false>::reloc_size;
3594           else if (size == 64)
3595             rel_size = Reloc_types<elfcpp::SHT_REL, 64, false>::reloc_size;
3596           else
3597             gold_unreachable();
3598         }
3599       else
3600         {
3601           rel_tag = elfcpp::DT_RELAENT;
3602           if (size == 32)
3603             rel_size = Reloc_types<elfcpp::SHT_RELA, 32, false>::reloc_size;
3604           else if (size == 64)
3605             rel_size = Reloc_types<elfcpp::SHT_RELA, 64, false>::reloc_size;
3606           else
3607             gold_unreachable();
3608         }
3609       odyn->add_constant(rel_tag, rel_size);
3610
3611       if (parameters->options().combreloc())
3612         {
3613           size_t c = dyn_rel->relative_reloc_count();
3614           if (c > 0)
3615             odyn->add_constant((use_rel
3616                                 ? elfcpp::DT_RELCOUNT
3617                                 : elfcpp::DT_RELACOUNT),
3618                                c);
3619         }
3620     }
3621
3622   if (add_debug && !parameters->options().shared())
3623     {
3624       // The value of the DT_DEBUG tag is filled in by the dynamic
3625       // linker at run time, and used by the debugger.
3626       odyn->add_constant(elfcpp::DT_DEBUG, 0);
3627     }
3628 }
3629
3630 // Finish the .dynamic section and PT_DYNAMIC segment.
3631
3632 void
3633 Layout::finish_dynamic_section(const Input_objects* input_objects,
3634                                const Symbol_table* symtab)
3635 {
3636   if (!this->script_options_->saw_phdrs_clause())
3637     {
3638       Output_segment* oseg = this->make_output_segment(elfcpp::PT_DYNAMIC,
3639                                                        (elfcpp::PF_R
3640                                                         | elfcpp::PF_W));
3641       oseg->add_output_section_to_nonload(this->dynamic_section_,
3642                                           elfcpp::PF_R | elfcpp::PF_W);
3643     }
3644
3645   Output_data_dynamic* const odyn = this->dynamic_data_;
3646
3647   for (Input_objects::Dynobj_iterator p = input_objects->dynobj_begin();
3648        p != input_objects->dynobj_end();
3649        ++p)
3650     {
3651       if (!(*p)->is_needed()
3652           && (*p)->input_file()->options().as_needed())
3653         {
3654           // This dynamic object was linked with --as-needed, but it
3655           // is not needed.
3656           continue;
3657         }
3658
3659       odyn->add_string(elfcpp::DT_NEEDED, (*p)->soname());
3660     }
3661
3662   if (parameters->options().shared())
3663     {
3664       const char* soname = parameters->options().soname();
3665       if (soname != NULL)
3666         odyn->add_string(elfcpp::DT_SONAME, soname);
3667     }
3668
3669   Symbol* sym = symtab->lookup(parameters->options().init());
3670   if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj())
3671     odyn->add_symbol(elfcpp::DT_INIT, sym);
3672
3673   sym = symtab->lookup(parameters->options().fini());
3674   if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj())
3675     odyn->add_symbol(elfcpp::DT_FINI, sym);
3676
3677   // Look for .init_array, .preinit_array and .fini_array by checking
3678   // section types.
3679   for(Layout::Section_list::const_iterator p = this->section_list_.begin();
3680       p != this->section_list_.end();
3681       ++p)
3682     switch((*p)->type())
3683       {
3684       case elfcpp::SHT_FINI_ARRAY:
3685         odyn->add_section_address(elfcpp::DT_FINI_ARRAY, *p);
3686         odyn->add_section_size(elfcpp::DT_FINI_ARRAYSZ, *p); 
3687         break;
3688       case elfcpp::SHT_INIT_ARRAY:
3689         odyn->add_section_address(elfcpp::DT_INIT_ARRAY, *p);
3690         odyn->add_section_size(elfcpp::DT_INIT_ARRAYSZ, *p); 
3691         break;
3692       case elfcpp::SHT_PREINIT_ARRAY:
3693         odyn->add_section_address(elfcpp::DT_PREINIT_ARRAY, *p);
3694         odyn->add_section_size(elfcpp::DT_PREINIT_ARRAYSZ, *p); 
3695         break;
3696       default:
3697         break;
3698       }
3699   
3700   // Add a DT_RPATH entry if needed.
3701   const General_options::Dir_list& rpath(parameters->options().rpath());
3702   if (!rpath.empty())
3703     {
3704       std::string rpath_val;
3705       for (General_options::Dir_list::const_iterator p = rpath.begin();
3706            p != rpath.end();
3707            ++p)
3708         {
3709           if (rpath_val.empty())
3710             rpath_val = p->name();
3711           else
3712             {
3713               // Eliminate duplicates.
3714               General_options::Dir_list::const_iterator q;
3715               for (q = rpath.begin(); q != p; ++q)
3716                 if (q->name() == p->name())
3717                   break;
3718               if (q == p)
3719                 {
3720                   rpath_val += ':';
3721                   rpath_val += p->name();
3722                 }
3723             }
3724         }
3725
3726       odyn->add_string(elfcpp::DT_RPATH, rpath_val);
3727       if (parameters->options().enable_new_dtags())
3728         odyn->add_string(elfcpp::DT_RUNPATH, rpath_val);
3729     }
3730
3731   // Look for text segments that have dynamic relocations.
3732   bool have_textrel = false;
3733   if (!this->script_options_->saw_sections_clause())
3734     {
3735       for (Segment_list::const_iterator p = this->segment_list_.begin();
3736            p != this->segment_list_.end();
3737            ++p)
3738         {
3739           if (((*p)->flags() & elfcpp::PF_W) == 0
3740               && (*p)->has_dynamic_reloc())
3741             {
3742               have_textrel = true;
3743               break;
3744             }
3745         }
3746     }
3747   else
3748     {
3749       // We don't know the section -> segment mapping, so we are
3750       // conservative and just look for readonly sections with
3751       // relocations.  If those sections wind up in writable segments,
3752       // then we have created an unnecessary DT_TEXTREL entry.
3753       for (Section_list::const_iterator p = this->section_list_.begin();
3754            p != this->section_list_.end();
3755            ++p)
3756         {
3757           if (((*p)->flags() & elfcpp::SHF_ALLOC) != 0
3758               && ((*p)->flags() & elfcpp::SHF_WRITE) == 0
3759               && ((*p)->has_dynamic_reloc()))
3760             {
3761               have_textrel = true;
3762               break;
3763             }
3764         }
3765     }
3766
3767   // Add a DT_FLAGS entry. We add it even if no flags are set so that
3768   // post-link tools can easily modify these flags if desired.
3769   unsigned int flags = 0;
3770   if (have_textrel)
3771     {
3772       // Add a DT_TEXTREL for compatibility with older loaders.
3773       odyn->add_constant(elfcpp::DT_TEXTREL, 0);
3774       flags |= elfcpp::DF_TEXTREL;
3775
3776       if (parameters->options().text())
3777         gold_error(_("read-only segment has dynamic relocations"));
3778       else if (parameters->options().warn_shared_textrel()
3779                && parameters->options().shared())
3780         gold_warning(_("shared library text segment is not shareable"));
3781     }
3782   if (parameters->options().shared() && this->has_static_tls())
3783     flags |= elfcpp::DF_STATIC_TLS;
3784   if (parameters->options().origin())
3785     flags |= elfcpp::DF_ORIGIN;
3786   if (parameters->options().Bsymbolic())
3787     {
3788       flags |= elfcpp::DF_SYMBOLIC;
3789       // Add DT_SYMBOLIC for compatibility with older loaders.
3790       odyn->add_constant(elfcpp::DT_SYMBOLIC, 0);
3791     }
3792   if (parameters->options().now())
3793     flags |= elfcpp::DF_BIND_NOW;
3794   odyn->add_constant(elfcpp::DT_FLAGS, flags);
3795
3796   flags = 0;
3797   if (parameters->options().initfirst())
3798     flags |= elfcpp::DF_1_INITFIRST;
3799   if (parameters->options().interpose())
3800     flags |= elfcpp::DF_1_INTERPOSE;
3801   if (parameters->options().loadfltr())
3802     flags |= elfcpp::DF_1_LOADFLTR;
3803   if (parameters->options().nodefaultlib())
3804     flags |= elfcpp::DF_1_NODEFLIB;
3805   if (parameters->options().nodelete())
3806     flags |= elfcpp::DF_1_NODELETE;
3807   if (parameters->options().nodlopen())
3808     flags |= elfcpp::DF_1_NOOPEN;
3809   if (parameters->options().nodump())
3810     flags |= elfcpp::DF_1_NODUMP;
3811   if (!parameters->options().shared())
3812     flags &= ~(elfcpp::DF_1_INITFIRST
3813                | elfcpp::DF_1_NODELETE
3814                | elfcpp::DF_1_NOOPEN);
3815   if (parameters->options().origin())
3816     flags |= elfcpp::DF_1_ORIGIN;
3817   if (parameters->options().now())
3818     flags |= elfcpp::DF_1_NOW;
3819   if (flags)
3820     odyn->add_constant(elfcpp::DT_FLAGS_1, flags);
3821 }
3822
3823 // Set the size of the _DYNAMIC symbol table to be the size of the
3824 // dynamic data.
3825
3826 void
3827 Layout::set_dynamic_symbol_size(const Symbol_table* symtab)
3828 {
3829   Output_data_dynamic* const odyn = this->dynamic_data_;
3830   odyn->finalize_data_size();
3831   off_t data_size = odyn->data_size();
3832   const int size = parameters->target().get_size();
3833   if (size == 32)
3834     symtab->get_sized_symbol<32>(this->dynamic_symbol_)->set_symsize(data_size);
3835   else if (size == 64)
3836     symtab->get_sized_symbol<64>(this->dynamic_symbol_)->set_symsize(data_size);
3837   else
3838     gold_unreachable();
3839 }
3840
3841 // The mapping of input section name prefixes to output section names.
3842 // In some cases one prefix is itself a prefix of another prefix; in
3843 // such a case the longer prefix must come first.  These prefixes are
3844 // based on the GNU linker default ELF linker script.
3845
3846 #define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 }
3847 const Layout::Section_name_mapping Layout::section_name_mapping[] =
3848 {
3849   MAPPING_INIT(".text.", ".text"),
3850   MAPPING_INIT(".ctors.", ".ctors"),
3851   MAPPING_INIT(".dtors.", ".dtors"),
3852   MAPPING_INIT(".rodata.", ".rodata"),
3853   MAPPING_INIT(".data.rel.ro.local", ".data.rel.ro.local"),
3854   MAPPING_INIT(".data.rel.ro", ".data.rel.ro"),
3855   MAPPING_INIT(".data.", ".data"),
3856   MAPPING_INIT(".bss.", ".bss"),
3857   MAPPING_INIT(".tdata.", ".tdata"),
3858   MAPPING_INIT(".tbss.", ".tbss"),
3859   MAPPING_INIT(".init_array.", ".init_array"),
3860   MAPPING_INIT(".fini_array.", ".fini_array"),
3861   MAPPING_INIT(".sdata.", ".sdata"),
3862   MAPPING_INIT(".sbss.", ".sbss"),
3863   // FIXME: In the GNU linker, .sbss2 and .sdata2 are handled
3864   // differently depending on whether it is creating a shared library.
3865   MAPPING_INIT(".sdata2.", ".sdata"),
3866   MAPPING_INIT(".sbss2.", ".sbss"),
3867   MAPPING_INIT(".lrodata.", ".lrodata"),
3868   MAPPING_INIT(".ldata.", ".ldata"),
3869   MAPPING_INIT(".lbss.", ".lbss"),
3870   MAPPING_INIT(".gcc_except_table.", ".gcc_except_table"),
3871   MAPPING_INIT(".gnu.linkonce.d.rel.ro.local.", ".data.rel.ro.local"),
3872   MAPPING_INIT(".gnu.linkonce.d.rel.ro.", ".data.rel.ro"),
3873   MAPPING_INIT(".gnu.linkonce.t.", ".text"),
3874   MAPPING_INIT(".gnu.linkonce.r.", ".rodata"),
3875   MAPPING_INIT(".gnu.linkonce.d.", ".data"),
3876   MAPPING_INIT(".gnu.linkonce.b.", ".bss"),
3877   MAPPING_INIT(".gnu.linkonce.s.", ".sdata"),
3878   MAPPING_INIT(".gnu.linkonce.sb.", ".sbss"),
3879   MAPPING_INIT(".gnu.linkonce.s2.", ".sdata"),
3880   MAPPING_INIT(".gnu.linkonce.sb2.", ".sbss"),
3881   MAPPING_INIT(".gnu.linkonce.wi.", ".debug_info"),
3882   MAPPING_INIT(".gnu.linkonce.td.", ".tdata"),
3883   MAPPING_INIT(".gnu.linkonce.tb.", ".tbss"),
3884   MAPPING_INIT(".gnu.linkonce.lr.", ".lrodata"),
3885   MAPPING_INIT(".gnu.linkonce.l.", ".ldata"),
3886   MAPPING_INIT(".gnu.linkonce.lb.", ".lbss"),
3887   MAPPING_INIT(".ARM.extab", ".ARM.extab"),
3888   MAPPING_INIT(".gnu.linkonce.armextab.", ".ARM.extab"),
3889   MAPPING_INIT(".ARM.exidx", ".ARM.exidx"),
3890   MAPPING_INIT(".gnu.linkonce.armexidx.", ".ARM.exidx"),
3891 };
3892 #undef MAPPING_INIT
3893
3894 const int Layout::section_name_mapping_count =
3895   (sizeof(Layout::section_name_mapping)
3896    / sizeof(Layout::section_name_mapping[0]));
3897
3898 // Choose the output section name to use given an input section name.
3899 // Set *PLEN to the length of the name.  *PLEN is initialized to the
3900 // length of NAME.
3901
3902 const char*
3903 Layout::output_section_name(const char* name, size_t* plen)
3904 {
3905   // gcc 4.3 generates the following sorts of section names when it
3906   // needs a section name specific to a function:
3907   //   .text.FN
3908   //   .rodata.FN
3909   //   .sdata2.FN
3910   //   .data.FN
3911   //   .data.rel.FN
3912   //   .data.rel.local.FN
3913   //   .data.rel.ro.FN
3914   //   .data.rel.ro.local.FN
3915   //   .sdata.FN
3916   //   .bss.FN
3917   //   .sbss.FN
3918   //   .tdata.FN
3919   //   .tbss.FN
3920
3921   // The GNU linker maps all of those to the part before the .FN,
3922   // except that .data.rel.local.FN is mapped to .data, and
3923   // .data.rel.ro.local.FN is mapped to .data.rel.ro.  The sections
3924   // beginning with .data.rel.ro.local are grouped together.
3925
3926   // For an anonymous namespace, the string FN can contain a '.'.
3927
3928   // Also of interest: .rodata.strN.N, .rodata.cstN, both of which the
3929   // GNU linker maps to .rodata.
3930
3931   // The .data.rel.ro sections are used with -z relro.  The sections
3932   // are recognized by name.  We use the same names that the GNU
3933   // linker does for these sections.
3934
3935   // It is hard to handle this in a principled way, so we don't even
3936   // try.  We use a table of mappings.  If the input section name is
3937   // not found in the table, we simply use it as the output section
3938   // name.
3939
3940   const Section_name_mapping* psnm = section_name_mapping;
3941   for (int i = 0; i < section_name_mapping_count; ++i, ++psnm)
3942     {
3943       if (strncmp(name, psnm->from, psnm->fromlen) == 0)
3944         {
3945           *plen = psnm->tolen;
3946           return psnm->to;
3947         }
3948     }
3949
3950   // Compressed debug sections should be mapped to the corresponding
3951   // uncompressed section.
3952   if (is_compressed_debug_section(name))
3953     {
3954       size_t len = strlen(name);
3955       char* uncompressed_name = new char[len];
3956       uncompressed_name[0] = '.';
3957       gold_assert(name[0] == '.' && name[1] == 'z');
3958       strncpy(&uncompressed_name[1], &name[2], len - 2);
3959       uncompressed_name[len - 1] = '\0';
3960       *plen = len - 1;
3961       return uncompressed_name;
3962     }
3963
3964   return name;
3965 }
3966
3967 // Check if a comdat group or .gnu.linkonce section with the given
3968 // NAME is selected for the link.  If there is already a section,
3969 // *KEPT_SECTION is set to point to the existing section and the
3970 // function returns false.  Otherwise, OBJECT, SHNDX, IS_COMDAT, and
3971 // IS_GROUP_NAME are recorded for this NAME in the layout object,
3972 // *KEPT_SECTION is set to the internal copy and the function returns
3973 // true.
3974
3975 bool
3976 Layout::find_or_add_kept_section(const std::string& name,
3977                                  Relobj* object,
3978                                  unsigned int shndx,
3979                                  bool is_comdat,
3980                                  bool is_group_name,
3981                                  Kept_section** kept_section)
3982 {
3983   // It's normal to see a couple of entries here, for the x86 thunk
3984   // sections.  If we see more than a few, we're linking a C++
3985   // program, and we resize to get more space to minimize rehashing.
3986   if (this->signatures_.size() > 4
3987       && !this->resized_signatures_)
3988     {
3989       reserve_unordered_map(&this->signatures_,
3990                             this->number_of_input_files_ * 64);
3991       this->resized_signatures_ = true;
3992     }
3993
3994   Kept_section candidate;
3995   std::pair<Signatures::iterator, bool> ins =
3996     this->signatures_.insert(std::make_pair(name, candidate));
3997
3998   if (kept_section != NULL)
3999     *kept_section = &ins.first->second;
4000   if (ins.second)
4001     {
4002       // This is the first time we've seen this signature.
4003       ins.first->second.set_object(object);
4004       ins.first->second.set_shndx(shndx);
4005       if (is_comdat)
4006         ins.first->second.set_is_comdat();
4007       if (is_group_name)
4008         ins.first->second.set_is_group_name();
4009       return true;
4010     }
4011
4012   // We have already seen this signature.
4013
4014   if (ins.first->second.is_group_name())
4015     {
4016       // We've already seen a real section group with this signature.
4017       // If the kept group is from a plugin object, and we're in the
4018       // replacement phase, accept the new one as a replacement.
4019       if (ins.first->second.object() == NULL
4020           && parameters->options().plugins()->in_replacement_phase())
4021         {
4022           ins.first->second.set_object(object);
4023           ins.first->second.set_shndx(shndx);
4024           return true;
4025         }
4026       return false;
4027     }
4028   else if (is_group_name)
4029     {
4030       // This is a real section group, and we've already seen a
4031       // linkonce section with this signature.  Record that we've seen
4032       // a section group, and don't include this section group.
4033       ins.first->second.set_is_group_name();
4034       return false;
4035     }
4036   else
4037     {
4038       // We've already seen a linkonce section and this is a linkonce
4039       // section.  These don't block each other--this may be the same
4040       // symbol name with different section types.
4041       return true;
4042     }
4043 }
4044
4045 // Store the allocated sections into the section list.
4046
4047 void
4048 Layout::get_allocated_sections(Section_list* section_list) const
4049 {
4050   for (Section_list::const_iterator p = this->section_list_.begin();
4051        p != this->section_list_.end();
4052        ++p)
4053     if (((*p)->flags() & elfcpp::SHF_ALLOC) != 0)
4054       section_list->push_back(*p);
4055 }
4056
4057 // Create an output segment.
4058
4059 Output_segment*
4060 Layout::make_output_segment(elfcpp::Elf_Word type, elfcpp::Elf_Word flags)
4061 {
4062   gold_assert(!parameters->options().relocatable());
4063   Output_segment* oseg = new Output_segment(type, flags);
4064   this->segment_list_.push_back(oseg);
4065
4066   if (type == elfcpp::PT_TLS)
4067     this->tls_segment_ = oseg;
4068   else if (type == elfcpp::PT_GNU_RELRO)
4069     this->relro_segment_ = oseg;
4070
4071   return oseg;
4072 }
4073
4074 // Write out the Output_sections.  Most won't have anything to write,
4075 // since most of the data will come from input sections which are
4076 // handled elsewhere.  But some Output_sections do have Output_data.
4077
4078 void
4079 Layout::write_output_sections(Output_file* of) const
4080 {
4081   for (Section_list::const_iterator p = this->section_list_.begin();
4082        p != this->section_list_.end();
4083        ++p)
4084     {
4085       if (!(*p)->after_input_sections())
4086         (*p)->write(of);
4087     }
4088 }
4089
4090 // Write out data not associated with a section or the symbol table.
4091
4092 void
4093 Layout::write_data(const Symbol_table* symtab, Output_file* of) const
4094 {
4095   if (!parameters->options().strip_all())
4096     {
4097       const Output_section* symtab_section = this->symtab_section_;
4098       for (Section_list::const_iterator p = this->section_list_.begin();
4099            p != this->section_list_.end();
4100            ++p)
4101         {
4102           if ((*p)->needs_symtab_index())
4103             {
4104               gold_assert(symtab_section != NULL);
4105               unsigned int index = (*p)->symtab_index();
4106               gold_assert(index > 0 && index != -1U);
4107               off_t off = (symtab_section->offset()
4108                            + index * symtab_section->entsize());
4109               symtab->write_section_symbol(*p, this->symtab_xindex_, of, off);
4110             }
4111         }
4112     }
4113
4114   const Output_section* dynsym_section = thi