1 // object.cc -- support for an object file for linking in gold
3 // Copyright 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013
4 // Free Software Foundation, Inc.
5 // Written by Ian Lance Taylor <iant@google.com>.
7 // This file is part of gold.
9 // This program is free software; you can redistribute it and/or modify
10 // it under the terms of the GNU General Public License as published by
11 // the Free Software Foundation; either version 3 of the License, or
12 // (at your option) any later version.
14 // This program is distributed in the hope that it will be useful,
15 // but WITHOUT ANY WARRANTY; without even the implied warranty of
16 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 // GNU General Public License for more details.
19 // You should have received a copy of the GNU General Public License
20 // along with this program; if not, write to the Free Software
21 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
22 // MA 02110-1301, USA.
30 #include "libiberty.h"
33 #include "target-select.h"
34 #include "dwarf_reader.h"
43 #include "compressed_output.h"
44 #include "incremental.h"
49 // Struct Read_symbols_data.
51 // Destroy any remaining File_view objects and buffers of decompressed
54 Read_symbols_data::~Read_symbols_data()
56 if (this->section_headers != NULL)
57 delete this->section_headers;
58 if (this->section_names != NULL)
59 delete this->section_names;
60 if (this->symbols != NULL)
62 if (this->symbol_names != NULL)
63 delete this->symbol_names;
64 if (this->versym != NULL)
66 if (this->verdef != NULL)
68 if (this->verneed != NULL)
74 // Initialize the symtab_xindex_ array. Find the SHT_SYMTAB_SHNDX
75 // section and read it in. SYMTAB_SHNDX is the index of the symbol
76 // table we care about.
78 template<int size, bool big_endian>
80 Xindex::initialize_symtab_xindex(Object* object, unsigned int symtab_shndx)
82 if (!this->symtab_xindex_.empty())
85 gold_assert(symtab_shndx != 0);
87 // Look through the sections in reverse order, on the theory that it
88 // is more likely to be near the end than the beginning.
89 unsigned int i = object->shnum();
93 if (object->section_type(i) == elfcpp::SHT_SYMTAB_SHNDX
94 && this->adjust_shndx(object->section_link(i)) == symtab_shndx)
96 this->read_symtab_xindex<size, big_endian>(object, i, NULL);
101 object->error(_("missing SHT_SYMTAB_SHNDX section"));
104 // Read in the symtab_xindex_ array, given the section index of the
105 // SHT_SYMTAB_SHNDX section. If PSHDRS is not NULL, it points at the
108 template<int size, bool big_endian>
110 Xindex::read_symtab_xindex(Object* object, unsigned int xindex_shndx,
111 const unsigned char* pshdrs)
113 section_size_type bytecount;
114 const unsigned char* contents;
116 contents = object->section_contents(xindex_shndx, &bytecount, false);
119 const unsigned char* p = (pshdrs
121 * elfcpp::Elf_sizes<size>::shdr_size));
122 typename elfcpp::Shdr<size, big_endian> shdr(p);
123 bytecount = convert_to_section_size_type(shdr.get_sh_size());
124 contents = object->get_view(shdr.get_sh_offset(), bytecount, true, false);
127 gold_assert(this->symtab_xindex_.empty());
128 this->symtab_xindex_.reserve(bytecount / 4);
129 for (section_size_type i = 0; i < bytecount; i += 4)
131 unsigned int shndx = elfcpp::Swap<32, big_endian>::readval(contents + i);
132 // We preadjust the section indexes we save.
133 this->symtab_xindex_.push_back(this->adjust_shndx(shndx));
137 // Symbol symndx has a section of SHN_XINDEX; return the real section
141 Xindex::sym_xindex_to_shndx(Object* object, unsigned int symndx)
143 if (symndx >= this->symtab_xindex_.size())
145 object->error(_("symbol %u out of range for SHT_SYMTAB_SHNDX section"),
147 return elfcpp::SHN_UNDEF;
149 unsigned int shndx = this->symtab_xindex_[symndx];
150 if (shndx < elfcpp::SHN_LORESERVE || shndx >= object->shnum())
152 object->error(_("extended index for symbol %u out of range: %u"),
154 return elfcpp::SHN_UNDEF;
161 // Report an error for this object file. This is used by the
162 // elfcpp::Elf_file interface, and also called by the Object code
166 Object::error(const char* format, ...) const
169 va_start(args, format);
171 if (vasprintf(&buf, format, args) < 0)
174 gold_error(_("%s: %s"), this->name().c_str(), buf);
178 // Return a view of the contents of a section.
181 Object::section_contents(unsigned int shndx, section_size_type* plen,
183 { return this->do_section_contents(shndx, plen, cache); }
185 // Read the section data into SD. This is code common to Sized_relobj_file
186 // and Sized_dynobj, so we put it into Object.
188 template<int size, bool big_endian>
190 Object::read_section_data(elfcpp::Elf_file<size, big_endian, Object>* elf_file,
191 Read_symbols_data* sd)
193 const int shdr_size = elfcpp::Elf_sizes<size>::shdr_size;
195 // Read the section headers.
196 const off_t shoff = elf_file->shoff();
197 const unsigned int shnum = this->shnum();
198 sd->section_headers = this->get_lasting_view(shoff, shnum * shdr_size,
201 // Read the section names.
202 const unsigned char* pshdrs = sd->section_headers->data();
203 const unsigned char* pshdrnames = pshdrs + elf_file->shstrndx() * shdr_size;
204 typename elfcpp::Shdr<size, big_endian> shdrnames(pshdrnames);
206 if (shdrnames.get_sh_type() != elfcpp::SHT_STRTAB)
207 this->error(_("section name section has wrong type: %u"),
208 static_cast<unsigned int>(shdrnames.get_sh_type()));
210 sd->section_names_size =
211 convert_to_section_size_type(shdrnames.get_sh_size());
212 sd->section_names = this->get_lasting_view(shdrnames.get_sh_offset(),
213 sd->section_names_size, false,
217 // If NAME is the name of a special .gnu.warning section, arrange for
218 // the warning to be issued. SHNDX is the section index. Return
219 // whether it is a warning section.
222 Object::handle_gnu_warning_section(const char* name, unsigned int shndx,
223 Symbol_table* symtab)
225 const char warn_prefix[] = ".gnu.warning.";
226 const int warn_prefix_len = sizeof warn_prefix - 1;
227 if (strncmp(name, warn_prefix, warn_prefix_len) == 0)
229 // Read the section contents to get the warning text. It would
230 // be nicer if we only did this if we have to actually issue a
231 // warning. Unfortunately, warnings are issued as we relocate
232 // sections. That means that we can not lock the object then,
233 // as we might try to issue the same warning multiple times
235 section_size_type len;
236 const unsigned char* contents = this->section_contents(shndx, &len,
240 const char* warning = name + warn_prefix_len;
241 contents = reinterpret_cast<const unsigned char*>(warning);
242 len = strlen(warning);
244 std::string warning(reinterpret_cast<const char*>(contents), len);
245 symtab->add_warning(name + warn_prefix_len, this, warning);
251 // If NAME is the name of the special section which indicates that
252 // this object was compiled with -fsplit-stack, mark it accordingly.
255 Object::handle_split_stack_section(const char* name)
257 if (strcmp(name, ".note.GNU-split-stack") == 0)
259 this->uses_split_stack_ = true;
262 if (strcmp(name, ".note.GNU-no-split-stack") == 0)
264 this->has_no_split_stack_ = true;
272 // To copy the symbols data read from the file to a local data structure.
273 // This function is called from do_layout only while doing garbage
277 Relobj::copy_symbols_data(Symbols_data* gc_sd, Read_symbols_data* sd,
278 unsigned int section_header_size)
280 gc_sd->section_headers_data =
281 new unsigned char[(section_header_size)];
282 memcpy(gc_sd->section_headers_data, sd->section_headers->data(),
283 section_header_size);
284 gc_sd->section_names_data =
285 new unsigned char[sd->section_names_size];
286 memcpy(gc_sd->section_names_data, sd->section_names->data(),
287 sd->section_names_size);
288 gc_sd->section_names_size = sd->section_names_size;
289 if (sd->symbols != NULL)
291 gc_sd->symbols_data =
292 new unsigned char[sd->symbols_size];
293 memcpy(gc_sd->symbols_data, sd->symbols->data(),
298 gc_sd->symbols_data = NULL;
300 gc_sd->symbols_size = sd->symbols_size;
301 gc_sd->external_symbols_offset = sd->external_symbols_offset;
302 if (sd->symbol_names != NULL)
304 gc_sd->symbol_names_data =
305 new unsigned char[sd->symbol_names_size];
306 memcpy(gc_sd->symbol_names_data, sd->symbol_names->data(),
307 sd->symbol_names_size);
311 gc_sd->symbol_names_data = NULL;
313 gc_sd->symbol_names_size = sd->symbol_names_size;
316 // This function determines if a particular section name must be included
317 // in the link. This is used during garbage collection to determine the
318 // roots of the worklist.
321 Relobj::is_section_name_included(const char* name)
323 if (is_prefix_of(".ctors", name)
324 || is_prefix_of(".dtors", name)
325 || is_prefix_of(".note", name)
326 || is_prefix_of(".init", name)
327 || is_prefix_of(".fini", name)
328 || is_prefix_of(".gcc_except_table", name)
329 || is_prefix_of(".jcr", name)
330 || is_prefix_of(".preinit_array", name)
331 || (is_prefix_of(".text", name)
332 && strstr(name, "personality"))
333 || (is_prefix_of(".data", name)
334 && strstr(name, "personality"))
335 || (is_prefix_of(".sdata", name)
336 && strstr(name, "personality"))
337 || (is_prefix_of(".gnu.linkonce.d", name)
338 && strstr(name, "personality")))
345 // Finalize the incremental relocation information. Allocates a block
346 // of relocation entries for each symbol, and sets the reloc_bases_
347 // array to point to the first entry in each block. If CLEAR_COUNTS
348 // is TRUE, also clear the per-symbol relocation counters.
351 Relobj::finalize_incremental_relocs(Layout* layout, bool clear_counts)
353 unsigned int nsyms = this->get_global_symbols()->size();
354 this->reloc_bases_ = new unsigned int[nsyms];
356 gold_assert(this->reloc_bases_ != NULL);
357 gold_assert(layout->incremental_inputs() != NULL);
359 unsigned int rindex = layout->incremental_inputs()->get_reloc_count();
360 for (unsigned int i = 0; i < nsyms; ++i)
362 this->reloc_bases_[i] = rindex;
363 rindex += this->reloc_counts_[i];
365 this->reloc_counts_[i] = 0;
367 layout->incremental_inputs()->set_reloc_count(rindex);
370 // Class Sized_relobj.
372 // Iterate over local symbols, calling a visitor class V for each GOT offset
373 // associated with a local symbol.
375 template<int size, bool big_endian>
377 Sized_relobj<size, big_endian>::do_for_all_local_got_entries(
378 Got_offset_list::Visitor* v) const
380 unsigned int nsyms = this->local_symbol_count();
381 for (unsigned int i = 0; i < nsyms; i++)
383 Local_got_offsets::const_iterator p = this->local_got_offsets_.find(i);
384 if (p != this->local_got_offsets_.end())
386 const Got_offset_list* got_offsets = p->second;
387 got_offsets->for_all_got_offsets(v);
392 // Class Sized_relobj_file.
394 template<int size, bool big_endian>
395 Sized_relobj_file<size, big_endian>::Sized_relobj_file(
396 const std::string& name,
397 Input_file* input_file,
399 const elfcpp::Ehdr<size, big_endian>& ehdr)
400 : Sized_relobj<size, big_endian>(name, input_file, offset),
401 elf_file_(this, ehdr),
403 local_symbol_count_(0),
404 output_local_symbol_count_(0),
405 output_local_dynsym_count_(0),
408 local_symbol_offset_(0),
409 local_dynsym_offset_(0),
411 local_plt_offsets_(),
412 kept_comdat_sections_(),
413 has_eh_frame_(false),
414 discarded_eh_frame_shndx_(-1U),
416 deferred_layout_relocs_(),
417 compressed_sections_()
419 this->e_type_ = ehdr.get_e_type();
422 template<int size, bool big_endian>
423 Sized_relobj_file<size, big_endian>::~Sized_relobj_file()
427 // Set up an object file based on the file header. This sets up the
428 // section information.
430 template<int size, bool big_endian>
432 Sized_relobj_file<size, big_endian>::do_setup()
434 const unsigned int shnum = this->elf_file_.shnum();
435 this->set_shnum(shnum);
438 // Find the SHT_SYMTAB section, given the section headers. The ELF
439 // standard says that maybe in the future there can be more than one
440 // SHT_SYMTAB section. Until somebody figures out how that could
441 // work, we assume there is only one.
443 template<int size, bool big_endian>
445 Sized_relobj_file<size, big_endian>::find_symtab(const unsigned char* pshdrs)
447 const unsigned int shnum = this->shnum();
448 this->symtab_shndx_ = 0;
451 // Look through the sections in reverse order, since gas tends
452 // to put the symbol table at the end.
453 const unsigned char* p = pshdrs + shnum * This::shdr_size;
454 unsigned int i = shnum;
455 unsigned int xindex_shndx = 0;
456 unsigned int xindex_link = 0;
460 p -= This::shdr_size;
461 typename This::Shdr shdr(p);
462 if (shdr.get_sh_type() == elfcpp::SHT_SYMTAB)
464 this->symtab_shndx_ = i;
465 if (xindex_shndx > 0 && xindex_link == i)
468 new Xindex(this->elf_file_.large_shndx_offset());
469 xindex->read_symtab_xindex<size, big_endian>(this,
472 this->set_xindex(xindex);
477 // Try to pick up the SHT_SYMTAB_SHNDX section, if there is
478 // one. This will work if it follows the SHT_SYMTAB
480 if (shdr.get_sh_type() == elfcpp::SHT_SYMTAB_SHNDX)
483 xindex_link = this->adjust_shndx(shdr.get_sh_link());
489 // Return the Xindex structure to use for object with lots of
492 template<int size, bool big_endian>
494 Sized_relobj_file<size, big_endian>::do_initialize_xindex()
496 gold_assert(this->symtab_shndx_ != -1U);
497 Xindex* xindex = new Xindex(this->elf_file_.large_shndx_offset());
498 xindex->initialize_symtab_xindex<size, big_endian>(this, this->symtab_shndx_);
502 // Return whether SHDR has the right type and flags to be a GNU
503 // .eh_frame section.
505 template<int size, bool big_endian>
507 Sized_relobj_file<size, big_endian>::check_eh_frame_flags(
508 const elfcpp::Shdr<size, big_endian>* shdr) const
510 elfcpp::Elf_Word sh_type = shdr->get_sh_type();
511 return ((sh_type == elfcpp::SHT_PROGBITS
512 || sh_type == elfcpp::SHT_X86_64_UNWIND)
513 && (shdr->get_sh_flags() & elfcpp::SHF_ALLOC) != 0);
516 // Find the section header with the given name.
518 template<int size, bool big_endian>
521 const unsigned char* pshdrs,
524 section_size_type names_size,
525 const unsigned char* hdr) const
527 const int shdr_size = elfcpp::Elf_sizes<size>::shdr_size;
528 const unsigned int shnum = this->shnum();
529 const unsigned char* hdr_end = pshdrs + shdr_size * shnum;
536 // We found HDR last time we were called, continue looking.
537 typename elfcpp::Shdr<size, big_endian> shdr(hdr);
538 sh_name = shdr.get_sh_name();
542 // Look for the next occurrence of NAME in NAMES.
543 // The fact that .shstrtab produced by current GNU tools is
544 // string merged means we shouldn't have both .not.foo and
545 // .foo in .shstrtab, and multiple .foo sections should all
546 // have the same sh_name. However, this is not guaranteed
547 // by the ELF spec and not all ELF object file producers may
549 size_t len = strlen(name) + 1;
550 const char *p = sh_name ? names + sh_name + len : names;
551 p = reinterpret_cast<const char*>(memmem(p, names_size - (p - names),
562 while (hdr < hdr_end)
564 typename elfcpp::Shdr<size, big_endian> shdr(hdr);
565 if (shdr.get_sh_name() == sh_name)
575 // Return whether there is a GNU .eh_frame section, given the section
576 // headers and the section names.
578 template<int size, bool big_endian>
580 Sized_relobj_file<size, big_endian>::find_eh_frame(
581 const unsigned char* pshdrs,
583 section_size_type names_size) const
585 const unsigned char* s = NULL;
589 s = this->template find_shdr<size, big_endian>(pshdrs, ".eh_frame",
590 names, names_size, s);
594 typename This::Shdr shdr(s);
595 if (this->check_eh_frame_flags(&shdr))
600 // Return TRUE if this is a section whose contents will be needed in the
601 // Add_symbols task. This function is only called for sections that have
602 // already passed the test in is_compressed_debug_section(), so we know
603 // that the section name begins with ".zdebug".
606 need_decompressed_section(const char* name)
608 // Skip over the ".zdebug" and a quick check for the "_".
613 #ifdef ENABLE_THREADS
614 // Decompressing these sections now will help only if we're
616 if (parameters->options().threads())
618 // We will need .zdebug_str if this is not an incremental link
619 // (i.e., we are processing string merge sections) or if we need
620 // to build a gdb index.
621 if ((!parameters->incremental() || parameters->options().gdb_index())
622 && strcmp(name, "str") == 0)
625 // We will need these other sections when building a gdb index.
626 if (parameters->options().gdb_index()
627 && (strcmp(name, "info") == 0
628 || strcmp(name, "types") == 0
629 || strcmp(name, "pubnames") == 0
630 || strcmp(name, "pubtypes") == 0
631 || strcmp(name, "ranges") == 0
632 || strcmp(name, "abbrev") == 0))
637 // Even when single-threaded, we will need .zdebug_str if this is
638 // not an incremental link and we are building a gdb index.
639 // Otherwise, we would decompress the section twice: once for
640 // string merge processing, and once for building the gdb index.
641 if (!parameters->incremental()
642 && parameters->options().gdb_index()
643 && strcmp(name, "str") == 0)
649 // Build a table for any compressed debug sections, mapping each section index
650 // to the uncompressed size and (if needed) the decompressed contents.
652 template<int size, bool big_endian>
653 Compressed_section_map*
654 build_compressed_section_map(
655 const unsigned char* pshdrs,
658 section_size_type names_size,
659 Sized_relobj_file<size, big_endian>* obj)
661 Compressed_section_map* uncompressed_map = new Compressed_section_map();
662 const unsigned int shdr_size = elfcpp::Elf_sizes<size>::shdr_size;
663 const unsigned char* p = pshdrs + shdr_size;
665 for (unsigned int i = 1; i < shnum; ++i, p += shdr_size)
667 typename elfcpp::Shdr<size, big_endian> shdr(p);
668 if (shdr.get_sh_type() == elfcpp::SHT_PROGBITS
669 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
671 if (shdr.get_sh_name() >= names_size)
673 obj->error(_("bad section name offset for section %u: %lu"),
674 i, static_cast<unsigned long>(shdr.get_sh_name()));
678 const char* name = names + shdr.get_sh_name();
679 if (is_compressed_debug_section(name))
681 section_size_type len;
682 const unsigned char* contents =
683 obj->section_contents(i, &len, false);
684 uint64_t uncompressed_size = get_uncompressed_size(contents, len);
685 Compressed_section_info info;
686 info.size = convert_to_section_size_type(uncompressed_size);
687 info.contents = NULL;
688 if (uncompressed_size != -1ULL)
690 unsigned char* uncompressed_data = NULL;
691 if (need_decompressed_section(name))
693 uncompressed_data = new unsigned char[uncompressed_size];
694 if (decompress_input_section(contents, len,
697 info.contents = uncompressed_data;
699 delete[] uncompressed_data;
701 (*uncompressed_map)[i] = info;
706 return uncompressed_map;
709 // Stash away info for a number of special sections.
710 // Return true if any of the sections found require local symbols to be read.
712 template<int size, bool big_endian>
714 Sized_relobj_file<size, big_endian>::do_find_special_sections(
715 Read_symbols_data* sd)
717 const unsigned char* const pshdrs = sd->section_headers->data();
718 const unsigned char* namesu = sd->section_names->data();
719 const char* names = reinterpret_cast<const char*>(namesu);
721 if (this->find_eh_frame(pshdrs, names, sd->section_names_size))
722 this->has_eh_frame_ = true;
724 if (memmem(names, sd->section_names_size, ".zdebug_", 8) != NULL)
725 this->compressed_sections_
726 = build_compressed_section_map(pshdrs, this->shnum(), names,
727 sd->section_names_size, this);
728 return (this->has_eh_frame_
729 || (!parameters->options().relocatable()
730 && parameters->options().gdb_index()
731 && (memmem(names, sd->section_names_size, "debug_info", 12) == 0
732 || memmem(names, sd->section_names_size, "debug_types",
736 // Read the sections and symbols from an object file.
738 template<int size, bool big_endian>
740 Sized_relobj_file<size, big_endian>::do_read_symbols(Read_symbols_data* sd)
742 this->read_section_data(&this->elf_file_, sd);
744 const unsigned char* const pshdrs = sd->section_headers->data();
746 this->find_symtab(pshdrs);
748 bool need_local_symbols = this->do_find_special_sections(sd);
751 sd->symbols_size = 0;
752 sd->external_symbols_offset = 0;
753 sd->symbol_names = NULL;
754 sd->symbol_names_size = 0;
756 if (this->symtab_shndx_ == 0)
758 // No symbol table. Weird but legal.
762 // Get the symbol table section header.
763 typename This::Shdr symtabshdr(pshdrs
764 + this->symtab_shndx_ * This::shdr_size);
765 gold_assert(symtabshdr.get_sh_type() == elfcpp::SHT_SYMTAB);
767 // If this object has a .eh_frame section, or if building a .gdb_index
768 // section and there is debug info, we need all the symbols.
769 // Otherwise we only need the external symbols. While it would be
770 // simpler to just always read all the symbols, I've seen object
771 // files with well over 2000 local symbols, which for a 64-bit
772 // object file format is over 5 pages that we don't need to read
775 const int sym_size = This::sym_size;
776 const unsigned int loccount = symtabshdr.get_sh_info();
777 this->local_symbol_count_ = loccount;
778 this->local_values_.resize(loccount);
779 section_offset_type locsize = loccount * sym_size;
780 off_t dataoff = symtabshdr.get_sh_offset();
781 section_size_type datasize =
782 convert_to_section_size_type(symtabshdr.get_sh_size());
783 off_t extoff = dataoff + locsize;
784 section_size_type extsize = datasize - locsize;
786 off_t readoff = need_local_symbols ? dataoff : extoff;
787 section_size_type readsize = need_local_symbols ? datasize : extsize;
791 // No external symbols. Also weird but also legal.
795 File_view* fvsymtab = this->get_lasting_view(readoff, readsize, true, false);
797 // Read the section header for the symbol names.
798 unsigned int strtab_shndx = this->adjust_shndx(symtabshdr.get_sh_link());
799 if (strtab_shndx >= this->shnum())
801 this->error(_("invalid symbol table name index: %u"), strtab_shndx);
804 typename This::Shdr strtabshdr(pshdrs + strtab_shndx * This::shdr_size);
805 if (strtabshdr.get_sh_type() != elfcpp::SHT_STRTAB)
807 this->error(_("symbol table name section has wrong type: %u"),
808 static_cast<unsigned int>(strtabshdr.get_sh_type()));
812 // Read the symbol names.
813 File_view* fvstrtab = this->get_lasting_view(strtabshdr.get_sh_offset(),
814 strtabshdr.get_sh_size(),
817 sd->symbols = fvsymtab;
818 sd->symbols_size = readsize;
819 sd->external_symbols_offset = need_local_symbols ? locsize : 0;
820 sd->symbol_names = fvstrtab;
821 sd->symbol_names_size =
822 convert_to_section_size_type(strtabshdr.get_sh_size());
825 // Return the section index of symbol SYM. Set *VALUE to its value in
826 // the object file. Set *IS_ORDINARY if this is an ordinary section
827 // index, not a special code between SHN_LORESERVE and SHN_HIRESERVE.
828 // Note that for a symbol which is not defined in this object file,
829 // this will set *VALUE to 0 and return SHN_UNDEF; it will not return
830 // the final value of the symbol in the link.
832 template<int size, bool big_endian>
834 Sized_relobj_file<size, big_endian>::symbol_section_and_value(unsigned int sym,
838 section_size_type symbols_size;
839 const unsigned char* symbols = this->section_contents(this->symtab_shndx_,
843 const size_t count = symbols_size / This::sym_size;
844 gold_assert(sym < count);
846 elfcpp::Sym<size, big_endian> elfsym(symbols + sym * This::sym_size);
847 *value = elfsym.get_st_value();
849 return this->adjust_sym_shndx(sym, elfsym.get_st_shndx(), is_ordinary);
852 // Return whether to include a section group in the link. LAYOUT is
853 // used to keep track of which section groups we have already seen.
854 // INDEX is the index of the section group and SHDR is the section
855 // header. If we do not want to include this group, we set bits in
856 // OMIT for each section which should be discarded.
858 template<int size, bool big_endian>
860 Sized_relobj_file<size, big_endian>::include_section_group(
861 Symbol_table* symtab,
865 const unsigned char* shdrs,
866 const char* section_names,
867 section_size_type section_names_size,
868 std::vector<bool>* omit)
870 // Read the section contents.
871 typename This::Shdr shdr(shdrs + index * This::shdr_size);
872 const unsigned char* pcon = this->get_view(shdr.get_sh_offset(),
873 shdr.get_sh_size(), true, false);
874 const elfcpp::Elf_Word* pword =
875 reinterpret_cast<const elfcpp::Elf_Word*>(pcon);
877 // The first word contains flags. We only care about COMDAT section
878 // groups. Other section groups are always included in the link
879 // just like ordinary sections.
880 elfcpp::Elf_Word flags = elfcpp::Swap<32, big_endian>::readval(pword);
882 // Look up the group signature, which is the name of a symbol. ELF
883 // uses a symbol name because some group signatures are long, and
884 // the name is generally already in the symbol table, so it makes
885 // sense to put the long string just once in .strtab rather than in
886 // both .strtab and .shstrtab.
888 // Get the appropriate symbol table header (this will normally be
889 // the single SHT_SYMTAB section, but in principle it need not be).
890 const unsigned int link = this->adjust_shndx(shdr.get_sh_link());
891 typename This::Shdr symshdr(this, this->elf_file_.section_header(link));
893 // Read the symbol table entry.
894 unsigned int symndx = shdr.get_sh_info();
895 if (symndx >= symshdr.get_sh_size() / This::sym_size)
897 this->error(_("section group %u info %u out of range"),
901 off_t symoff = symshdr.get_sh_offset() + symndx * This::sym_size;
902 const unsigned char* psym = this->get_view(symoff, This::sym_size, true,
904 elfcpp::Sym<size, big_endian> sym(psym);
906 // Read the symbol table names.
907 section_size_type symnamelen;
908 const unsigned char* psymnamesu;
909 psymnamesu = this->section_contents(this->adjust_shndx(symshdr.get_sh_link()),
911 const char* psymnames = reinterpret_cast<const char*>(psymnamesu);
913 // Get the section group signature.
914 if (sym.get_st_name() >= symnamelen)
916 this->error(_("symbol %u name offset %u out of range"),
917 symndx, sym.get_st_name());
921 std::string signature(psymnames + sym.get_st_name());
923 // It seems that some versions of gas will create a section group
924 // associated with a section symbol, and then fail to give a name to
925 // the section symbol. In such a case, use the name of the section.
926 if (signature[0] == '\0' && sym.get_st_type() == elfcpp::STT_SECTION)
929 unsigned int sym_shndx = this->adjust_sym_shndx(symndx,
932 if (!is_ordinary || sym_shndx >= this->shnum())
934 this->error(_("symbol %u invalid section index %u"),
938 typename This::Shdr member_shdr(shdrs + sym_shndx * This::shdr_size);
939 if (member_shdr.get_sh_name() < section_names_size)
940 signature = section_names + member_shdr.get_sh_name();
943 // Record this section group in the layout, and see whether we've already
944 // seen one with the same signature.
947 Kept_section* kept_section = NULL;
949 if ((flags & elfcpp::GRP_COMDAT) == 0)
951 include_group = true;
956 include_group = layout->find_or_add_kept_section(signature,
958 true, &kept_section);
962 if (is_comdat && include_group)
964 Incremental_inputs* incremental_inputs = layout->incremental_inputs();
965 if (incremental_inputs != NULL)
966 incremental_inputs->report_comdat_group(this, signature.c_str());
969 size_t count = shdr.get_sh_size() / sizeof(elfcpp::Elf_Word);
971 std::vector<unsigned int> shndxes;
972 bool relocate_group = include_group && parameters->options().relocatable();
974 shndxes.reserve(count - 1);
976 for (size_t i = 1; i < count; ++i)
978 elfcpp::Elf_Word shndx =
979 this->adjust_shndx(elfcpp::Swap<32, big_endian>::readval(pword + i));
982 shndxes.push_back(shndx);
984 if (shndx >= this->shnum())
986 this->error(_("section %u in section group %u out of range"),
991 // Check for an earlier section number, since we're going to get
992 // it wrong--we may have already decided to include the section.
994 this->error(_("invalid section group %u refers to earlier section %u"),
997 // Get the name of the member section.
998 typename This::Shdr member_shdr(shdrs + shndx * This::shdr_size);
999 if (member_shdr.get_sh_name() >= section_names_size)
1001 // This is an error, but it will be diagnosed eventually
1002 // in do_layout, so we don't need to do anything here but
1006 std::string mname(section_names + member_shdr.get_sh_name());
1011 kept_section->add_comdat_section(mname, shndx,
1012 member_shdr.get_sh_size());
1016 (*omit)[shndx] = true;
1020 Relobj* kept_object = kept_section->object();
1021 if (kept_section->is_comdat())
1023 // Find the corresponding kept section, and store
1024 // that info in the discarded section table.
1025 unsigned int kept_shndx;
1027 if (kept_section->find_comdat_section(mname, &kept_shndx,
1030 // We don't keep a mapping for this section if
1031 // it has a different size. The mapping is only
1032 // used for relocation processing, and we don't
1033 // want to treat the sections as similar if the
1034 // sizes are different. Checking the section
1035 // size is the approach used by the GNU linker.
1036 if (kept_size == member_shdr.get_sh_size())
1037 this->set_kept_comdat_section(shndx, kept_object,
1043 // The existing section is a linkonce section. Add
1044 // a mapping if there is exactly one section in the
1045 // group (which is true when COUNT == 2) and if it
1046 // is the same size.
1048 && (kept_section->linkonce_size()
1049 == member_shdr.get_sh_size()))
1050 this->set_kept_comdat_section(shndx, kept_object,
1051 kept_section->shndx());
1058 layout->layout_group(symtab, this, index, name, signature.c_str(),
1059 shdr, flags, &shndxes);
1061 return include_group;
1064 // Whether to include a linkonce section in the link. NAME is the
1065 // name of the section and SHDR is the section header.
1067 // Linkonce sections are a GNU extension implemented in the original
1068 // GNU linker before section groups were defined. The semantics are
1069 // that we only include one linkonce section with a given name. The
1070 // name of a linkonce section is normally .gnu.linkonce.T.SYMNAME,
1071 // where T is the type of section and SYMNAME is the name of a symbol.
1072 // In an attempt to make linkonce sections interact well with section
1073 // groups, we try to identify SYMNAME and use it like a section group
1074 // signature. We want to block section groups with that signature,
1075 // but not other linkonce sections with that signature. We also use
1076 // the full name of the linkonce section as a normal section group
1079 template<int size, bool big_endian>
1081 Sized_relobj_file<size, big_endian>::include_linkonce_section(
1085 const elfcpp::Shdr<size, big_endian>& shdr)
1087 typename elfcpp::Elf_types<size>::Elf_WXword sh_size = shdr.get_sh_size();
1088 // In general the symbol name we want will be the string following
1089 // the last '.'. However, we have to handle the case of
1090 // .gnu.linkonce.t.__i686.get_pc_thunk.bx, which was generated by
1091 // some versions of gcc. So we use a heuristic: if the name starts
1092 // with ".gnu.linkonce.t.", we use everything after that. Otherwise
1093 // we look for the last '.'. We can't always simply skip
1094 // ".gnu.linkonce.X", because we have to deal with cases like
1095 // ".gnu.linkonce.d.rel.ro.local".
1096 const char* const linkonce_t = ".gnu.linkonce.t.";
1097 const char* symname;
1098 if (strncmp(name, linkonce_t, strlen(linkonce_t)) == 0)
1099 symname = name + strlen(linkonce_t);
1101 symname = strrchr(name, '.') + 1;
1102 std::string sig1(symname);
1103 std::string sig2(name);
1104 Kept_section* kept1;
1105 Kept_section* kept2;
1106 bool include1 = layout->find_or_add_kept_section(sig1, this, index, false,
1108 bool include2 = layout->find_or_add_kept_section(sig2, this, index, false,
1113 // We are not including this section because we already saw the
1114 // name of the section as a signature. This normally implies
1115 // that the kept section is another linkonce section. If it is
1116 // the same size, record it as the section which corresponds to
1118 if (kept2->object() != NULL
1119 && !kept2->is_comdat()
1120 && kept2->linkonce_size() == sh_size)
1121 this->set_kept_comdat_section(index, kept2->object(), kept2->shndx());
1125 // The section is being discarded on the basis of its symbol
1126 // name. This means that the corresponding kept section was
1127 // part of a comdat group, and it will be difficult to identify
1128 // the specific section within that group that corresponds to
1129 // this linkonce section. We'll handle the simple case where
1130 // the group has only one member section. Otherwise, it's not
1131 // worth the effort.
1132 unsigned int kept_shndx;
1134 if (kept1->object() != NULL
1135 && kept1->is_comdat()
1136 && kept1->find_single_comdat_section(&kept_shndx, &kept_size)
1137 && kept_size == sh_size)
1138 this->set_kept_comdat_section(index, kept1->object(), kept_shndx);
1142 kept1->set_linkonce_size(sh_size);
1143 kept2->set_linkonce_size(sh_size);
1146 return include1 && include2;
1149 // Layout an input section.
1151 template<int size, bool big_endian>
1153 Sized_relobj_file<size, big_endian>::layout_section(
1157 const typename This::Shdr& shdr,
1158 unsigned int reloc_shndx,
1159 unsigned int reloc_type)
1162 Output_section* os = layout->layout(this, shndx, name, shdr,
1163 reloc_shndx, reloc_type, &offset);
1165 this->output_sections()[shndx] = os;
1167 this->section_offsets()[shndx] = invalid_address;
1169 this->section_offsets()[shndx] = convert_types<Address, off_t>(offset);
1171 // If this section requires special handling, and if there are
1172 // relocs that apply to it, then we must do the special handling
1173 // before we apply the relocs.
1174 if (offset == -1 && reloc_shndx != 0)
1175 this->set_relocs_must_follow_section_writes();
1178 // Layout an input .eh_frame section.
1180 template<int size, bool big_endian>
1182 Sized_relobj_file<size, big_endian>::layout_eh_frame_section(
1184 const unsigned char* symbols_data,
1185 section_size_type symbols_size,
1186 const unsigned char* symbol_names_data,
1187 section_size_type symbol_names_size,
1189 const typename This::Shdr& shdr,
1190 unsigned int reloc_shndx,
1191 unsigned int reloc_type)
1193 gold_assert(this->has_eh_frame_);
1196 Output_section* os = layout->layout_eh_frame(this,
1206 this->output_sections()[shndx] = os;
1207 if (os == NULL || offset == -1)
1209 // An object can contain at most one section holding exception
1210 // frame information.
1211 gold_assert(this->discarded_eh_frame_shndx_ == -1U);
1212 this->discarded_eh_frame_shndx_ = shndx;
1213 this->section_offsets()[shndx] = invalid_address;
1216 this->section_offsets()[shndx] = convert_types<Address, off_t>(offset);
1218 // If this section requires special handling, and if there are
1219 // relocs that aply to it, then we must do the special handling
1220 // before we apply the relocs.
1221 if (os != NULL && offset == -1 && reloc_shndx != 0)
1222 this->set_relocs_must_follow_section_writes();
1225 // Lay out the input sections. We walk through the sections and check
1226 // whether they should be included in the link. If they should, we
1227 // pass them to the Layout object, which will return an output section
1229 // This function is called twice sometimes, two passes, when mapping
1230 // of input sections to output sections must be delayed.
1231 // This is true for the following :
1232 // * Garbage collection (--gc-sections): Some input sections will be
1233 // discarded and hence the assignment must wait until the second pass.
1234 // In the first pass, it is for setting up some sections as roots to
1235 // a work-list for --gc-sections and to do comdat processing.
1236 // * Identical Code Folding (--icf=<safe,all>): Some input sections
1237 // will be folded and hence the assignment must wait.
1238 // * Using plugins to map some sections to unique segments: Mapping
1239 // some sections to unique segments requires mapping them to unique
1240 // output sections too. This can be done via plugins now and this
1241 // information is not available in the first pass.
1243 template<int size, bool big_endian>
1245 Sized_relobj_file<size, big_endian>::do_layout(Symbol_table* symtab,
1247 Read_symbols_data* sd)
1249 const unsigned int shnum = this->shnum();
1251 /* Should this function be called twice? */
1252 bool is_two_pass = (parameters->options().gc_sections()
1253 || parameters->options().icf_enabled()
1254 || layout->is_unique_segment_for_sections_specified());
1256 /* Only one of is_pass_one and is_pass_two is true. Both are false when
1257 a two-pass approach is not needed. */
1258 bool is_pass_one = false;
1259 bool is_pass_two = false;
1261 Symbols_data* gc_sd = NULL;
1263 /* Check if do_layout needs to be two-pass. If so, find out which pass
1264 should happen. In the first pass, the data in sd is saved to be used
1265 later in the second pass. */
1268 gc_sd = this->get_symbols_data();
1271 gold_assert(sd != NULL);
1276 if (parameters->options().gc_sections())
1277 gold_assert(symtab->gc()->is_worklist_ready());
1278 if (parameters->options().icf_enabled())
1279 gold_assert(symtab->icf()->is_icf_ready());
1289 // During garbage collection save the symbols data to use it when
1290 // re-entering this function.
1291 gc_sd = new Symbols_data;
1292 this->copy_symbols_data(gc_sd, sd, This::shdr_size * shnum);
1293 this->set_symbols_data(gc_sd);
1296 const unsigned char* section_headers_data = NULL;
1297 section_size_type section_names_size;
1298 const unsigned char* symbols_data = NULL;
1299 section_size_type symbols_size;
1300 const unsigned char* symbol_names_data = NULL;
1301 section_size_type symbol_names_size;
1305 section_headers_data = gc_sd->section_headers_data;
1306 section_names_size = gc_sd->section_names_size;
1307 symbols_data = gc_sd->symbols_data;
1308 symbols_size = gc_sd->symbols_size;
1309 symbol_names_data = gc_sd->symbol_names_data;
1310 symbol_names_size = gc_sd->symbol_names_size;
1314 section_headers_data = sd->section_headers->data();
1315 section_names_size = sd->section_names_size;
1316 if (sd->symbols != NULL)
1317 symbols_data = sd->symbols->data();
1318 symbols_size = sd->symbols_size;
1319 if (sd->symbol_names != NULL)
1320 symbol_names_data = sd->symbol_names->data();
1321 symbol_names_size = sd->symbol_names_size;
1324 // Get the section headers.
1325 const unsigned char* shdrs = section_headers_data;
1326 const unsigned char* pshdrs;
1328 // Get the section names.
1329 const unsigned char* pnamesu = (is_two_pass
1330 ? gc_sd->section_names_data
1331 : sd->section_names->data());
1333 const char* pnames = reinterpret_cast<const char*>(pnamesu);
1335 // If any input files have been claimed by plugins, we need to defer
1336 // actual layout until the replacement files have arrived.
1337 const bool should_defer_layout =
1338 (parameters->options().has_plugins()
1339 && parameters->options().plugins()->should_defer_layout());
1340 unsigned int num_sections_to_defer = 0;
1342 // For each section, record the index of the reloc section if any.
1343 // Use 0 to mean that there is no reloc section, -1U to mean that
1344 // there is more than one.
1345 std::vector<unsigned int> reloc_shndx(shnum, 0);
1346 std::vector<unsigned int> reloc_type(shnum, elfcpp::SHT_NULL);
1347 // Skip the first, dummy, section.
1348 pshdrs = shdrs + This::shdr_size;
1349 for (unsigned int i = 1; i < shnum; ++i, pshdrs += This::shdr_size)
1351 typename This::Shdr shdr(pshdrs);
1353 // Count the number of sections whose layout will be deferred.
1354 if (should_defer_layout && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC))
1355 ++num_sections_to_defer;
1357 unsigned int sh_type = shdr.get_sh_type();
1358 if (sh_type == elfcpp::SHT_REL || sh_type == elfcpp::SHT_RELA)
1360 unsigned int target_shndx = this->adjust_shndx(shdr.get_sh_info());
1361 if (target_shndx == 0 || target_shndx >= shnum)
1363 this->error(_("relocation section %u has bad info %u"),
1368 if (reloc_shndx[target_shndx] != 0)
1369 reloc_shndx[target_shndx] = -1U;
1372 reloc_shndx[target_shndx] = i;
1373 reloc_type[target_shndx] = sh_type;
1378 Output_sections& out_sections(this->output_sections());
1379 std::vector<Address>& out_section_offsets(this->section_offsets());
1383 out_sections.resize(shnum);
1384 out_section_offsets.resize(shnum);
1387 // If we are only linking for symbols, then there is nothing else to
1389 if (this->input_file()->just_symbols())
1393 delete sd->section_headers;
1394 sd->section_headers = NULL;
1395 delete sd->section_names;
1396 sd->section_names = NULL;
1401 if (num_sections_to_defer > 0)
1403 parameters->options().plugins()->add_deferred_layout_object(this);
1404 this->deferred_layout_.reserve(num_sections_to_defer);
1407 // Whether we've seen a .note.GNU-stack section.
1408 bool seen_gnu_stack = false;
1409 // The flags of a .note.GNU-stack section.
1410 uint64_t gnu_stack_flags = 0;
1412 // Keep track of which sections to omit.
1413 std::vector<bool> omit(shnum, false);
1415 // Keep track of reloc sections when emitting relocations.
1416 const bool relocatable = parameters->options().relocatable();
1417 const bool emit_relocs = (relocatable
1418 || parameters->options().emit_relocs());
1419 std::vector<unsigned int> reloc_sections;
1421 // Keep track of .eh_frame sections.
1422 std::vector<unsigned int> eh_frame_sections;
1424 // Keep track of .debug_info and .debug_types sections.
1425 std::vector<unsigned int> debug_info_sections;
1426 std::vector<unsigned int> debug_types_sections;
1428 // Skip the first, dummy, section.
1429 pshdrs = shdrs + This::shdr_size;
1430 for (unsigned int i = 1; i < shnum; ++i, pshdrs += This::shdr_size)
1432 typename This::Shdr shdr(pshdrs);
1434 if (shdr.get_sh_name() >= section_names_size)
1436 this->error(_("bad section name offset for section %u: %lu"),
1437 i, static_cast<unsigned long>(shdr.get_sh_name()));
1441 const char* name = pnames + shdr.get_sh_name();
1445 if (this->handle_gnu_warning_section(name, i, symtab))
1447 if (!relocatable && !parameters->options().shared())
1451 // The .note.GNU-stack section is special. It gives the
1452 // protection flags that this object file requires for the stack
1454 if (strcmp(name, ".note.GNU-stack") == 0)
1456 seen_gnu_stack = true;
1457 gnu_stack_flags |= shdr.get_sh_flags();
1461 // The .note.GNU-split-stack section is also special. It
1462 // indicates that the object was compiled with
1464 if (this->handle_split_stack_section(name))
1466 if (!relocatable && !parameters->options().shared())
1470 // Skip attributes section.
1471 if (parameters->target().is_attributes_section(name))
1476 bool discard = omit[i];
1479 if (shdr.get_sh_type() == elfcpp::SHT_GROUP)
1481 if (!this->include_section_group(symtab, layout, i, name,
1487 else if ((shdr.get_sh_flags() & elfcpp::SHF_GROUP) == 0
1488 && Layout::is_linkonce(name))
1490 if (!this->include_linkonce_section(layout, i, name, shdr))
1495 // Add the section to the incremental inputs layout.
1496 Incremental_inputs* incremental_inputs = layout->incremental_inputs();
1497 if (incremental_inputs != NULL
1499 && can_incremental_update(shdr.get_sh_type()))
1501 off_t sh_size = shdr.get_sh_size();
1502 section_size_type uncompressed_size;
1503 if (this->section_is_compressed(i, &uncompressed_size))
1504 sh_size = uncompressed_size;
1505 incremental_inputs->report_input_section(this, i, name, sh_size);
1510 // Do not include this section in the link.
1511 out_sections[i] = NULL;
1512 out_section_offsets[i] = invalid_address;
1517 if (is_pass_one && parameters->options().gc_sections())
1519 if (this->is_section_name_included(name)
1520 || layout->keep_input_section (this, name)
1521 || shdr.get_sh_type() == elfcpp::SHT_INIT_ARRAY
1522 || shdr.get_sh_type() == elfcpp::SHT_FINI_ARRAY)
1524 symtab->gc()->worklist().push(Section_id(this, i));
1526 // If the section name XXX can be represented as a C identifier
1527 // it cannot be discarded if there are references to
1528 // __start_XXX and __stop_XXX symbols. These need to be
1529 // specially handled.
1530 if (is_cident(name))
1532 symtab->gc()->add_cident_section(name, Section_id(this, i));
1536 // When doing a relocatable link we are going to copy input
1537 // reloc sections into the output. We only want to copy the
1538 // ones associated with sections which are not being discarded.
1539 // However, we don't know that yet for all sections. So save
1540 // reloc sections and process them later. Garbage collection is
1541 // not triggered when relocatable code is desired.
1543 && (shdr.get_sh_type() == elfcpp::SHT_REL
1544 || shdr.get_sh_type() == elfcpp::SHT_RELA))
1546 reloc_sections.push_back(i);
1550 if (relocatable && shdr.get_sh_type() == elfcpp::SHT_GROUP)
1553 // The .eh_frame section is special. It holds exception frame
1554 // information that we need to read in order to generate the
1555 // exception frame header. We process these after all the other
1556 // sections so that the exception frame reader can reliably
1557 // determine which sections are being discarded, and discard the
1558 // corresponding information.
1560 && strcmp(name, ".eh_frame") == 0
1561 && this->check_eh_frame_flags(&shdr))
1565 out_sections[i] = reinterpret_cast<Output_section*>(1);
1566 out_section_offsets[i] = invalid_address;
1568 else if (should_defer_layout)
1569 this->deferred_layout_.push_back(Deferred_layout(i, name,
1574 eh_frame_sections.push_back(i);
1578 if (is_pass_two && parameters->options().gc_sections())
1580 // This is executed during the second pass of garbage
1581 // collection. do_layout has been called before and some
1582 // sections have been already discarded. Simply ignore
1583 // such sections this time around.
1584 if (out_sections[i] == NULL)
1586 gold_assert(out_section_offsets[i] == invalid_address);
1589 if (((shdr.get_sh_flags() & elfcpp::SHF_ALLOC) != 0)
1590 && symtab->gc()->is_section_garbage(this, i))
1592 if (parameters->options().print_gc_sections())
1593 gold_info(_("%s: removing unused section from '%s'"
1595 program_name, this->section_name(i).c_str(),
1596 this->name().c_str());
1597 out_sections[i] = NULL;
1598 out_section_offsets[i] = invalid_address;
1603 if (is_pass_two && parameters->options().icf_enabled())
1605 if (out_sections[i] == NULL)
1607 gold_assert(out_section_offsets[i] == invalid_address);
1610 if (((shdr.get_sh_flags() & elfcpp::SHF_ALLOC) != 0)
1611 && symtab->icf()->is_section_folded(this, i))
1613 if (parameters->options().print_icf_sections())
1616 symtab->icf()->get_folded_section(this, i);
1617 Relobj* folded_obj =
1618 reinterpret_cast<Relobj*>(folded.first);
1619 gold_info(_("%s: ICF folding section '%s' in file '%s'"
1620 "into '%s' in file '%s'"),
1621 program_name, this->section_name(i).c_str(),
1622 this->name().c_str(),
1623 folded_obj->section_name(folded.second).c_str(),
1624 folded_obj->name().c_str());
1626 out_sections[i] = NULL;
1627 out_section_offsets[i] = invalid_address;
1632 // Defer layout here if input files are claimed by plugins. When gc
1633 // is turned on this function is called twice. For the second call
1634 // should_defer_layout should be false.
1635 if (should_defer_layout && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC))
1637 gold_assert(!is_pass_two);
1638 this->deferred_layout_.push_back(Deferred_layout(i, name,
1642 // Put dummy values here; real values will be supplied by
1643 // do_layout_deferred_sections.
1644 out_sections[i] = reinterpret_cast<Output_section*>(2);
1645 out_section_offsets[i] = invalid_address;
1649 // During gc_pass_two if a section that was previously deferred is
1650 // found, do not layout the section as layout_deferred_sections will
1651 // do it later from gold.cc.
1653 && (out_sections[i] == reinterpret_cast<Output_section*>(2)))
1658 // This is during garbage collection. The out_sections are
1659 // assigned in the second call to this function.
1660 out_sections[i] = reinterpret_cast<Output_section*>(1);
1661 out_section_offsets[i] = invalid_address;
1665 // When garbage collection is switched on the actual layout
1666 // only happens in the second call.
1667 this->layout_section(layout, i, name, shdr, reloc_shndx[i],
1670 // When generating a .gdb_index section, we do additional
1671 // processing of .debug_info and .debug_types sections after all
1672 // the other sections for the same reason as above.
1674 && parameters->options().gdb_index()
1675 && !(shdr.get_sh_flags() & elfcpp::SHF_ALLOC))
1677 if (strcmp(name, ".debug_info") == 0
1678 || strcmp(name, ".zdebug_info") == 0)
1679 debug_info_sections.push_back(i);
1680 else if (strcmp(name, ".debug_types") == 0
1681 || strcmp(name, ".zdebug_types") == 0)
1682 debug_types_sections.push_back(i);
1688 layout->layout_gnu_stack(seen_gnu_stack, gnu_stack_flags, this);
1690 // When doing a relocatable link handle the reloc sections at the
1691 // end. Garbage collection and Identical Code Folding is not
1692 // turned on for relocatable code.
1694 this->size_relocatable_relocs();
1696 gold_assert(!is_two_pass || reloc_sections.empty());
1698 for (std::vector<unsigned int>::const_iterator p = reloc_sections.begin();
1699 p != reloc_sections.end();
1702 unsigned int i = *p;
1703 const unsigned char* pshdr;
1704 pshdr = section_headers_data + i * This::shdr_size;
1705 typename This::Shdr shdr(pshdr);
1707 unsigned int data_shndx = this->adjust_shndx(shdr.get_sh_info());
1708 if (data_shndx >= shnum)
1710 // We already warned about this above.
1714 Output_section* data_section = out_sections[data_shndx];
1715 if (data_section == reinterpret_cast<Output_section*>(2))
1717 // The layout for the data section was deferred, so we need
1718 // to defer the relocation section, too.
1719 const char* name = pnames + shdr.get_sh_name();
1720 this->deferred_layout_relocs_.push_back(
1721 Deferred_layout(i, name, pshdr, 0, elfcpp::SHT_NULL));
1722 out_sections[i] = reinterpret_cast<Output_section*>(2);
1723 out_section_offsets[i] = invalid_address;
1726 if (data_section == NULL)
1728 out_sections[i] = NULL;
1729 out_section_offsets[i] = invalid_address;
1733 Relocatable_relocs* rr = new Relocatable_relocs();
1734 this->set_relocatable_relocs(i, rr);
1736 Output_section* os = layout->layout_reloc(this, i, shdr, data_section,
1738 out_sections[i] = os;
1739 out_section_offsets[i] = invalid_address;
1742 // Handle the .eh_frame sections at the end.
1743 gold_assert(!is_pass_one || eh_frame_sections.empty());
1744 for (std::vector<unsigned int>::const_iterator p = eh_frame_sections.begin();
1745 p != eh_frame_sections.end();
1748 unsigned int i = *p;
1749 const unsigned char* pshdr;
1750 pshdr = section_headers_data + i * This::shdr_size;
1751 typename This::Shdr shdr(pshdr);
1753 this->layout_eh_frame_section(layout,
1764 // When building a .gdb_index section, scan the .debug_info and
1765 // .debug_types sections.
1766 gold_assert(!is_pass_one
1767 || (debug_info_sections.empty() && debug_types_sections.empty()));
1768 for (std::vector<unsigned int>::const_iterator p
1769 = debug_info_sections.begin();
1770 p != debug_info_sections.end();
1773 unsigned int i = *p;
1774 layout->add_to_gdb_index(false, this, symbols_data, symbols_size,
1775 i, reloc_shndx[i], reloc_type[i]);
1777 for (std::vector<unsigned int>::const_iterator p
1778 = debug_types_sections.begin();
1779 p != debug_types_sections.end();
1782 unsigned int i = *p;
1783 layout->add_to_gdb_index(true, this, symbols_data, symbols_size,
1784 i, reloc_shndx[i], reloc_type[i]);
1789 delete[] gc_sd->section_headers_data;
1790 delete[] gc_sd->section_names_data;
1791 delete[] gc_sd->symbols_data;
1792 delete[] gc_sd->symbol_names_data;
1793 this->set_symbols_data(NULL);
1797 delete sd->section_headers;
1798 sd->section_headers = NULL;
1799 delete sd->section_names;
1800 sd->section_names = NULL;
1804 // Layout sections whose layout was deferred while waiting for
1805 // input files from a plugin.
1807 template<int size, bool big_endian>
1809 Sized_relobj_file<size, big_endian>::do_layout_deferred_sections(Layout* layout)
1811 typename std::vector<Deferred_layout>::iterator deferred;
1813 for (deferred = this->deferred_layout_.begin();
1814 deferred != this->deferred_layout_.end();
1817 typename This::Shdr shdr(deferred->shdr_data_);
1819 if (!parameters->options().relocatable()
1820 && deferred->name_ == ".eh_frame"
1821 && this->check_eh_frame_flags(&shdr))
1823 // Checking is_section_included is not reliable for
1824 // .eh_frame sections, because they do not have an output
1825 // section. This is not a problem normally because we call
1826 // layout_eh_frame_section unconditionally, but when
1827 // deferring sections that is not true. We don't want to
1828 // keep all .eh_frame sections because that will cause us to
1829 // keep all sections that they refer to, which is the wrong
1830 // way around. Instead, the eh_frame code will discard
1831 // .eh_frame sections that refer to discarded sections.
1833 // Reading the symbols again here may be slow.
1834 Read_symbols_data sd;
1835 this->read_symbols(&sd);
1836 this->layout_eh_frame_section(layout,
1839 sd.symbol_names->data(),
1840 sd.symbol_names_size,
1843 deferred->reloc_shndx_,
1844 deferred->reloc_type_);
1848 // If the section is not included, it is because the garbage collector
1849 // decided it is not needed. Avoid reverting that decision.
1850 if (!this->is_section_included(deferred->shndx_))
1853 this->layout_section(layout, deferred->shndx_, deferred->name_.c_str(),
1854 shdr, deferred->reloc_shndx_,
1855 deferred->reloc_type_);
1858 this->deferred_layout_.clear();
1860 // Now handle the deferred relocation sections.
1862 Output_sections& out_sections(this->output_sections());
1863 std::vector<Address>& out_section_offsets(this->section_offsets());
1865 for (deferred = this->deferred_layout_relocs_.begin();
1866 deferred != this->deferred_layout_relocs_.end();
1869 unsigned int shndx = deferred->shndx_;
1870 typename This::Shdr shdr(deferred->shdr_data_);
1871 unsigned int data_shndx = this->adjust_shndx(shdr.get_sh_info());
1873 Output_section* data_section = out_sections[data_shndx];
1874 if (data_section == NULL)
1876 out_sections[shndx] = NULL;
1877 out_section_offsets[shndx] = invalid_address;
1881 Relocatable_relocs* rr = new Relocatable_relocs();
1882 this->set_relocatable_relocs(shndx, rr);
1884 Output_section* os = layout->layout_reloc(this, shndx, shdr,
1886 out_sections[shndx] = os;
1887 out_section_offsets[shndx] = invalid_address;
1891 // Add the symbols to the symbol table.
1893 template<int size, bool big_endian>
1895 Sized_relobj_file<size, big_endian>::do_add_symbols(Symbol_table* symtab,
1896 Read_symbols_data* sd,
1899 if (sd->symbols == NULL)
1901 gold_assert(sd->symbol_names == NULL);
1905 const int sym_size = This::sym_size;
1906 size_t symcount = ((sd->symbols_size - sd->external_symbols_offset)
1908 if (symcount * sym_size != sd->symbols_size - sd->external_symbols_offset)
1910 this->error(_("size of symbols is not multiple of symbol size"));
1914 this->symbols_.resize(symcount);
1916 const char* sym_names =
1917 reinterpret_cast<const char*>(sd->symbol_names->data());
1918 symtab->add_from_relobj(this,
1919 sd->symbols->data() + sd->external_symbols_offset,
1920 symcount, this->local_symbol_count_,
1921 sym_names, sd->symbol_names_size,
1923 &this->defined_count_);
1927 delete sd->symbol_names;
1928 sd->symbol_names = NULL;
1931 // Find out if this object, that is a member of a lib group, should be included
1932 // in the link. We check every symbol defined by this object. If the symbol
1933 // table has a strong undefined reference to that symbol, we have to include
1936 template<int size, bool big_endian>
1937 Archive::Should_include
1938 Sized_relobj_file<size, big_endian>::do_should_include_member(
1939 Symbol_table* symtab,
1941 Read_symbols_data* sd,
1944 char* tmpbuf = NULL;
1945 size_t tmpbuflen = 0;
1946 const char* sym_names =
1947 reinterpret_cast<const char*>(sd->symbol_names->data());
1948 const unsigned char* syms =
1949 sd->symbols->data() + sd->external_symbols_offset;
1950 const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
1951 size_t symcount = ((sd->symbols_size - sd->external_symbols_offset)
1954 const unsigned char* p = syms;
1956 for (size_t i = 0; i < symcount; ++i, p += sym_size)
1958 elfcpp::Sym<size, big_endian> sym(p);
1959 unsigned int st_shndx = sym.get_st_shndx();
1960 if (st_shndx == elfcpp::SHN_UNDEF)
1963 unsigned int st_name = sym.get_st_name();
1964 const char* name = sym_names + st_name;
1966 Archive::Should_include t = Archive::should_include_member(symtab,
1972 if (t == Archive::SHOULD_INCLUDE_YES)
1981 return Archive::SHOULD_INCLUDE_UNKNOWN;
1984 // Iterate over global defined symbols, calling a visitor class V for each.
1986 template<int size, bool big_endian>
1988 Sized_relobj_file<size, big_endian>::do_for_all_global_symbols(
1989 Read_symbols_data* sd,
1990 Library_base::Symbol_visitor_base* v)
1992 const char* sym_names =
1993 reinterpret_cast<const char*>(sd->symbol_names->data());
1994 const unsigned char* syms =
1995 sd->symbols->data() + sd->external_symbols_offset;
1996 const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
1997 size_t symcount = ((sd->symbols_size - sd->external_symbols_offset)
1999 const unsigned char* p = syms;
2001 for (size_t i = 0; i < symcount; ++i, p += sym_size)
2003 elfcpp::Sym<size, big_endian> sym(p);
2004 if (sym.get_st_shndx() != elfcpp::SHN_UNDEF)
2005 v->visit(sym_names + sym.get_st_name());
2009 // Return whether the local symbol SYMNDX has a PLT offset.
2011 template<int size, bool big_endian>
2013 Sized_relobj_file<size, big_endian>::local_has_plt_offset(
2014 unsigned int symndx) const
2016 typename Local_plt_offsets::const_iterator p =
2017 this->local_plt_offsets_.find(symndx);
2018 return p != this->local_plt_offsets_.end();
2021 // Get the PLT offset of a local symbol.
2023 template<int size, bool big_endian>
2025 Sized_relobj_file<size, big_endian>::do_local_plt_offset(
2026 unsigned int symndx) const
2028 typename Local_plt_offsets::const_iterator p =
2029 this->local_plt_offsets_.find(symndx);
2030 gold_assert(p != this->local_plt_offsets_.end());
2034 // Set the PLT offset of a local symbol.
2036 template<int size, bool big_endian>
2038 Sized_relobj_file<size, big_endian>::set_local_plt_offset(
2039 unsigned int symndx, unsigned int plt_offset)
2041 std::pair<typename Local_plt_offsets::iterator, bool> ins =
2042 this->local_plt_offsets_.insert(std::make_pair(symndx, plt_offset));
2043 gold_assert(ins.second);
2046 // First pass over the local symbols. Here we add their names to
2047 // *POOL and *DYNPOOL, and we store the symbol value in
2048 // THIS->LOCAL_VALUES_. This function is always called from a
2049 // singleton thread. This is followed by a call to
2050 // finalize_local_symbols.
2052 template<int size, bool big_endian>
2054 Sized_relobj_file<size, big_endian>::do_count_local_symbols(Stringpool* pool,
2055 Stringpool* dynpool)
2057 gold_assert(this->symtab_shndx_ != -1U);
2058 if (this->symtab_shndx_ == 0)
2060 // This object has no symbols. Weird but legal.
2064 // Read the symbol table section header.
2065 const unsigned int symtab_shndx = this->symtab_shndx_;
2066 typename This::Shdr symtabshdr(this,
2067 this->elf_file_.section_header(symtab_shndx));
2068 gold_assert(symtabshdr.get_sh_type() == elfcpp::SHT_SYMTAB);
2070 // Read the local symbols.
2071 const int sym_size = This::sym_size;
2072 const unsigned int loccount = this->local_symbol_count_;
2073 gold_assert(loccount == symtabshdr.get_sh_info());
2074 off_t locsize = loccount * sym_size;
2075 const unsigned char* psyms = this->get_view(symtabshdr.get_sh_offset(),
2076 locsize, true, true);
2078 // Read the symbol names.
2079 const unsigned int strtab_shndx =
2080 this->adjust_shndx(symtabshdr.get_sh_link());
2081 section_size_type strtab_size;
2082 const unsigned char* pnamesu = this->section_contents(strtab_shndx,
2085 const char* pnames = reinterpret_cast<const char*>(pnamesu);
2087 // Loop over the local symbols.
2089 const Output_sections& out_sections(this->output_sections());
2090 unsigned int shnum = this->shnum();
2091 unsigned int count = 0;
2092 unsigned int dyncount = 0;
2093 // Skip the first, dummy, symbol.
2095 bool strip_all = parameters->options().strip_all();
2096 bool discard_all = parameters->options().discard_all();
2097 bool discard_locals = parameters->options().discard_locals();
2098 for (unsigned int i = 1; i < loccount; ++i, psyms += sym_size)
2100 elfcpp::Sym<size, big_endian> sym(psyms);
2102 Symbol_value<size>& lv(this->local_values_[i]);
2105 unsigned int shndx = this->adjust_sym_shndx(i, sym.get_st_shndx(),
2107 lv.set_input_shndx(shndx, is_ordinary);
2109 if (sym.get_st_type() == elfcpp::STT_SECTION)
2110 lv.set_is_section_symbol();
2111 else if (sym.get_st_type() == elfcpp::STT_TLS)
2112 lv.set_is_tls_symbol();
2113 else if (sym.get_st_type() == elfcpp::STT_GNU_IFUNC)
2114 lv.set_is_ifunc_symbol();
2116 // Save the input symbol value for use in do_finalize_local_symbols().
2117 lv.set_input_value(sym.get_st_value());
2119 // Decide whether this symbol should go into the output file.
2121 if ((shndx < shnum && out_sections[shndx] == NULL)
2122 || shndx == this->discarded_eh_frame_shndx_)
2124 lv.set_no_output_symtab_entry();
2125 gold_assert(!lv.needs_output_dynsym_entry());
2129 if (sym.get_st_type() == elfcpp::STT_SECTION
2130 || !this->adjust_local_symbol(&lv))
2132 lv.set_no_output_symtab_entry();
2133 gold_assert(!lv.needs_output_dynsym_entry());
2137 if (sym.get_st_name() >= strtab_size)
2139 this->error(_("local symbol %u section name out of range: %u >= %u"),
2140 i, sym.get_st_name(),
2141 static_cast<unsigned int>(strtab_size));
2142 lv.set_no_output_symtab_entry();
2146 const char* name = pnames + sym.get_st_name();
2148 // If needed, add the symbol to the dynamic symbol table string pool.
2149 if (lv.needs_output_dynsym_entry())
2151 dynpool->add(name, true, NULL);
2156 || (discard_all && lv.may_be_discarded_from_output_symtab()))
2158 lv.set_no_output_symtab_entry();
2162 // If --discard-locals option is used, discard all temporary local
2163 // symbols. These symbols start with system-specific local label
2164 // prefixes, typically .L for ELF system. We want to be compatible
2165 // with GNU ld so here we essentially use the same check in
2166 // bfd_is_local_label(). The code is different because we already
2169 // - the symbol is local and thus cannot have global or weak binding.
2170 // - the symbol is not a section symbol.
2171 // - the symbol has a name.
2173 // We do not discard a symbol if it needs a dynamic symbol entry.
2175 && sym.get_st_type() != elfcpp::STT_FILE
2176 && !lv.needs_output_dynsym_entry()
2177 && lv.may_be_discarded_from_output_symtab()
2178 && parameters->target().is_local_label_name(name))
2180 lv.set_no_output_symtab_entry();
2184 // Discard the local symbol if -retain_symbols_file is specified
2185 // and the local symbol is not in that file.
2186 if (!parameters->options().should_retain_symbol(name))
2188 lv.set_no_output_symtab_entry();
2192 // Add the symbol to the symbol table string pool.
2193 pool->add(name, true, NULL);
2197 this->output_local_symbol_count_ = count;
2198 this->output_local_dynsym_count_ = dyncount;
2201 // Compute the final value of a local symbol.
2203 template<int size, bool big_endian>
2204 typename Sized_relobj_file<size, big_endian>::Compute_final_local_value_status
2205 Sized_relobj_file<size, big_endian>::compute_final_local_value_internal(
2207 const Symbol_value<size>* lv_in,
2208 Symbol_value<size>* lv_out,
2210 const Output_sections& out_sections,
2211 const std::vector<Address>& out_offsets,
2212 const Symbol_table* symtab)
2214 // We are going to overwrite *LV_OUT, if it has a merged symbol value,
2215 // we may have a memory leak.
2216 gold_assert(lv_out->has_output_value());
2219 unsigned int shndx = lv_in->input_shndx(&is_ordinary);
2221 // Set the output symbol value.
2225 if (shndx == elfcpp::SHN_ABS || Symbol::is_common_shndx(shndx))
2226 lv_out->set_output_value(lv_in->input_value());
2229 this->error(_("unknown section index %u for local symbol %u"),
2231 lv_out->set_output_value(0);
2232 return This::CFLV_ERROR;
2237 if (shndx >= this->shnum())
2239 this->error(_("local symbol %u section index %u out of range"),
2241 lv_out->set_output_value(0);
2242 return This::CFLV_ERROR;
2245 Output_section* os = out_sections[shndx];
2246 Address secoffset = out_offsets[shndx];
2247 if (symtab->is_section_folded(this, shndx))
2249 gold_assert(os == NULL && secoffset == invalid_address);
2250 // Get the os of the section it is folded onto.
2251 Section_id folded = symtab->icf()->get_folded_section(this,
2253 gold_assert(folded.first != NULL);
2254 Sized_relobj_file<size, big_endian>* folded_obj = reinterpret_cast
2255 <Sized_relobj_file<size, big_endian>*>(folded.first);
2256 os = folded_obj->output_section(folded.second);
2257 gold_assert(os != NULL);
2258 secoffset = folded_obj->get_output_section_offset(folded.second);
2260 // This could be a relaxed input section.
2261 if (secoffset == invalid_address)
2263 const Output_relaxed_input_section* relaxed_section =
2264 os->find_relaxed_input_section(folded_obj, folded.second);
2265 gold_assert(relaxed_section != NULL);
2266 secoffset = relaxed_section->address() - os->address();
2272 // This local symbol belongs to a section we are discarding.
2273 // In some cases when applying relocations later, we will
2274 // attempt to match it to the corresponding kept section,
2275 // so we leave the input value unchanged here.
2276 return This::CFLV_DISCARDED;
2278 else if (secoffset == invalid_address)
2282 // This is a SHF_MERGE section or one which otherwise
2283 // requires special handling.
2284 if (shndx == this->discarded_eh_frame_shndx_)
2286 // This local symbol belongs to a discarded .eh_frame
2287 // section. Just treat it like the case in which
2288 // os == NULL above.
2289 gold_assert(this->has_eh_frame_);
2290 return This::CFLV_DISCARDED;
2292 else if (!lv_in->is_section_symbol())
2294 // This is not a section symbol. We can determine
2295 // the final value now.
2296 lv_out->set_output_value(
2297 os->output_address(this, shndx, lv_in->input_value()));
2299 else if (!os->find_starting_output_address(this, shndx, &start))
2301 // This is a section symbol, but apparently not one in a
2302 // merged section. First check to see if this is a relaxed
2303 // input section. If so, use its address. Otherwise just
2304 // use the start of the output section. This happens with
2305 // relocatable links when the input object has section
2306 // symbols for arbitrary non-merge sections.
2307 const Output_section_data* posd =
2308 os->find_relaxed_input_section(this, shndx);
2311 Address relocatable_link_adjustment =
2312 relocatable ? os->address() : 0;
2313 lv_out->set_output_value(posd->address()
2314 - relocatable_link_adjustment);
2317 lv_out->set_output_value(os->address());
2321 // We have to consider the addend to determine the
2322 // value to use in a relocation. START is the start
2323 // of this input section. If we are doing a relocatable
2324 // link, use offset from start output section instead of
2326 Address adjusted_start =
2327 relocatable ? start - os->address() : start;
2328 Merged_symbol_value<size>* msv =
2329 new Merged_symbol_value<size>(lv_in->input_value(),
2331 lv_out->set_merged_symbol_value(msv);
2334 else if (lv_in->is_tls_symbol())
2335 lv_out->set_output_value(os->tls_offset()
2337 + lv_in->input_value());
2339 lv_out->set_output_value((relocatable ? 0 : os->address())
2341 + lv_in->input_value());
2343 return This::CFLV_OK;
2346 // Compute final local symbol value. R_SYM is the index of a local
2347 // symbol in symbol table. LV points to a symbol value, which is
2348 // expected to hold the input value and to be over-written by the
2349 // final value. SYMTAB points to a symbol table. Some targets may want
2350 // to know would-be-finalized local symbol values in relaxation.
2351 // Hence we provide this method. Since this method updates *LV, a
2352 // callee should make a copy of the original local symbol value and
2353 // use the copy instead of modifying an object's local symbols before
2354 // everything is finalized. The caller should also free up any allocated
2355 // memory in the return value in *LV.
2356 template<int size, bool big_endian>
2357 typename Sized_relobj_file<size, big_endian>::Compute_final_local_value_status
2358 Sized_relobj_file<size, big_endian>::compute_final_local_value(
2360 const Symbol_value<size>* lv_in,
2361 Symbol_value<size>* lv_out,
2362 const Symbol_table* symtab)
2364 // This is just a wrapper of compute_final_local_value_internal.
2365 const bool relocatable = parameters->options().relocatable();
2366 const Output_sections& out_sections(this->output_sections());
2367 const std::vector<Address>& out_offsets(this->section_offsets());
2368 return this->compute_final_local_value_internal(r_sym, lv_in, lv_out,
2369 relocatable, out_sections,
2370 out_offsets, symtab);
2373 // Finalize the local symbols. Here we set the final value in
2374 // THIS->LOCAL_VALUES_ and set their output symbol table indexes.
2375 // This function is always called from a singleton thread. The actual
2376 // output of the local symbols will occur in a separate task.
2378 template<int size, bool big_endian>
2380 Sized_relobj_file<size, big_endian>::do_finalize_local_symbols(
2383 Symbol_table* symtab)
2385 gold_assert(off == static_cast<off_t>(align_address(off, size >> 3)));
2387 const unsigned int loccount = this->local_symbol_count_;
2388 this->local_symbol_offset_ = off;
2390 const bool relocatable = parameters->options().relocatable();
2391 const Output_sections& out_sections(this->output_sections());
2392 const std::vector<Address>& out_offsets(this->section_offsets());
2394 for (unsigned int i = 1; i < loccount; ++i)
2396 Symbol_value<size>* lv = &this->local_values_[i];
2398 Compute_final_local_value_status cflv_status =
2399 this->compute_final_local_value_internal(i, lv, lv, relocatable,
2400 out_sections, out_offsets,
2402 switch (cflv_status)
2405 if (!lv->is_output_symtab_index_set())
2407 lv->set_output_symtab_index(index);
2411 case CFLV_DISCARDED:
2422 // Set the output dynamic symbol table indexes for the local variables.
2424 template<int size, bool big_endian>
2426 Sized_relobj_file<size, big_endian>::do_set_local_dynsym_indexes(
2429 const unsigned int loccount = this->local_symbol_count_;
2430 for (unsigned int i = 1; i < loccount; ++i)
2432 Symbol_value<size>& lv(this->local_values_[i]);
2433 if (lv.needs_output_dynsym_entry())
2435 lv.set_output_dynsym_index(index);
2442 // Set the offset where local dynamic symbol information will be stored.
2443 // Returns the count of local symbols contributed to the symbol table by
2446 template<int size, bool big_endian>
2448 Sized_relobj_file<size, big_endian>::do_set_local_dynsym_offset(off_t off)
2450 gold_assert(off == static_cast<off_t>(align_address(off, size >> 3)));
2451 this->local_dynsym_offset_ = off;
2452 return this->output_local_dynsym_count_;
2455 // If Symbols_data is not NULL get the section flags from here otherwise
2456 // get it from the file.
2458 template<int size, bool big_endian>
2460 Sized_relobj_file<size, big_endian>::do_section_flags(unsigned int shndx)
2462 Symbols_data* sd = this->get_symbols_data();
2465 const unsigned char* pshdrs = sd->section_headers_data
2466 + This::shdr_size * shndx;
2467 typename This::Shdr shdr(pshdrs);
2468 return shdr.get_sh_flags();
2470 // If sd is NULL, read the section header from the file.
2471 return this->elf_file_.section_flags(shndx);
2474 // Get the section's ent size from Symbols_data. Called by get_section_contents
2477 template<int size, bool big_endian>
2479 Sized_relobj_file<size, big_endian>::do_section_entsize(unsigned int shndx)
2481 Symbols_data* sd = this->get_symbols_data();
2482 gold_assert(sd != NULL);
2484 const unsigned char* pshdrs = sd->section_headers_data
2485 + This::shdr_size * shndx;
2486 typename This::Shdr shdr(pshdrs);
2487 return shdr.get_sh_entsize();
2490 // Write out the local symbols.
2492 template<int size, bool big_endian>
2494 Sized_relobj_file<size, big_endian>::write_local_symbols(
2496 const Stringpool* sympool,
2497 const Stringpool* dynpool,
2498 Output_symtab_xindex* symtab_xindex,
2499 Output_symtab_xindex* dynsym_xindex,
2502 const bool strip_all = parameters->options().strip_all();
2505 if (this->output_local_dynsym_count_ == 0)
2507 this->output_local_symbol_count_ = 0;
2510 gold_assert(this->symtab_shndx_ != -1U);
2511 if (this->symtab_shndx_ == 0)
2513 // This object has no symbols. Weird but legal.
2517 // Read the symbol table section header.
2518 const unsigned int symtab_shndx = this->symtab_shndx_;
2519 typename This::Shdr symtabshdr(this,
2520 this->elf_file_.section_header(symtab_shndx));
2521 gold_assert(symtabshdr.get_sh_type() == elfcpp::SHT_SYMTAB);
2522 const unsigned int loccount = this->local_symbol_count_;
2523 gold_assert(loccount == symtabshdr.get_sh_info());
2525 // Read the local symbols.
2526 const int sym_size = This::sym_size;
2527 off_t locsize = loccount * sym_size;
2528 const unsigned char* psyms = this->get_view(symtabshdr.get_sh_offset(),
2529 locsize, true, false);
2531 // Read the symbol names.
2532 const unsigned int strtab_shndx =
2533 this->adjust_shndx(symtabshdr.get_sh_link());
2534 section_size_type strtab_size;
2535 const unsigned char* pnamesu = this->section_contents(strtab_shndx,
2538 const char* pnames = reinterpret_cast<const char*>(pnamesu);
2540 // Get views into the output file for the portions of the symbol table
2541 // and the dynamic symbol table that we will be writing.
2542 off_t output_size = this->output_local_symbol_count_ * sym_size;
2543 unsigned char* oview = NULL;
2544 if (output_size > 0)
2545 oview = of->get_output_view(symtab_off + this->local_symbol_offset_,
2548 off_t dyn_output_size = this->output_local_dynsym_count_ * sym_size;
2549 unsigned char* dyn_oview = NULL;
2550 if (dyn_output_size > 0)
2551 dyn_oview = of->get_output_view(this->local_dynsym_offset_,
2554 const Output_sections out_sections(this->output_sections());
2556 gold_assert(this->local_values_.size() == loccount);
2558 unsigned char* ov = oview;
2559 unsigned char* dyn_ov = dyn_oview;
2561 for (unsigned int i = 1; i < loccount; ++i, psyms += sym_size)
2563 elfcpp::Sym<size, big_endian> isym(psyms);
2565 Symbol_value<size>& lv(this->local_values_[i]);
2568 unsigned int st_shndx = this->adjust_sym_shndx(i, isym.get_st_shndx(),
2572 gold_assert(st_shndx < out_sections.size());
2573 if (out_sections[st_shndx] == NULL)
2575 st_shndx = out_sections[st_shndx]->out_shndx();
2576 if (st_shndx >= elfcpp::SHN_LORESERVE)
2578 if (lv.has_output_symtab_entry())
2579 symtab_xindex->add(lv.output_symtab_index(), st_shndx);
2580 if (lv.has_output_dynsym_entry())
2581 dynsym_xindex->add(lv.output_dynsym_index(), st_shndx);
2582 st_shndx = elfcpp::SHN_XINDEX;
2586 // Write the symbol to the output symbol table.
2587 if (lv.has_output_symtab_entry())
2589 elfcpp::Sym_write<size, big_endian> osym(ov);
2591 gold_assert(isym.get_st_name() < strtab_size);
2592 const char* name = pnames + isym.get_st_name();
2593 osym.put_st_name(sympool->get_offset(name));
2594 osym.put_st_value(this->local_values_[i].value(this, 0));
2595 osym.put_st_size(isym.get_st_size());
2596 osym.put_st_info(isym.get_st_info());
2597 osym.put_st_other(isym.get_st_other());
2598 osym.put_st_shndx(st_shndx);
2603 // Write the symbol to the output dynamic symbol table.
2604 if (lv.has_output_dynsym_entry())
2606 gold_assert(dyn_ov < dyn_oview + dyn_output_size);
2607 elfcpp::Sym_write<size, big_endian> osym(dyn_ov);
2609 gold_assert(isym.get_st_name() < strtab_size);
2610 const char* name = pnames + isym.get_st_name();
2611 osym.put_st_name(dynpool->get_offset(name));
2612 osym.put_st_value(this->local_values_[i].value(this, 0));
2613 osym.put_st_size(isym.get_st_size());
2614 osym.put_st_info(isym.get_st_info());
2615 osym.put_st_other(isym.get_st_other());
2616 osym.put_st_shndx(st_shndx);
2623 if (output_size > 0)
2625 gold_assert(ov - oview == output_size);
2626 of->write_output_view(symtab_off + this->local_symbol_offset_,
2627 output_size, oview);
2630 if (dyn_output_size > 0)
2632 gold_assert(dyn_ov - dyn_oview == dyn_output_size);
2633 of->write_output_view(this->local_dynsym_offset_, dyn_output_size,
2638 // Set *INFO to symbolic information about the offset OFFSET in the
2639 // section SHNDX. Return true if we found something, false if we
2642 template<int size, bool big_endian>
2644 Sized_relobj_file<size, big_endian>::get_symbol_location_info(
2647 Symbol_location_info* info)
2649 if (this->symtab_shndx_ == 0)
2652 section_size_type symbols_size;
2653 const unsigned char* symbols = this->section_contents(this->symtab_shndx_,
2657 unsigned int symbol_names_shndx =
2658 this->adjust_shndx(this->section_link(this->symtab_shndx_));
2659 section_size_type names_size;
2660 const unsigned char* symbol_names_u =
2661 this->section_contents(symbol_names_shndx, &names_size, false);
2662 const char* symbol_names = reinterpret_cast<const char*>(symbol_names_u);
2664 const int sym_size = This::sym_size;
2665 const size_t count = symbols_size / sym_size;
2667 const unsigned char* p = symbols;
2668 for (size_t i = 0; i < count; ++i, p += sym_size)
2670 elfcpp::Sym<size, big_endian> sym(p);
2672 if (sym.get_st_type() == elfcpp::STT_FILE)
2674 if (sym.get_st_name() >= names_size)
2675 info->source_file = "(invalid)";
2677 info->source_file = symbol_names + sym.get_st_name();
2682 unsigned int st_shndx = this->adjust_sym_shndx(i, sym.get_st_shndx(),
2685 && st_shndx == shndx
2686 && static_cast<off_t>(sym.get_st_value()) <= offset
2687 && (static_cast<off_t>(sym.get_st_value() + sym.get_st_size())
2690 info->enclosing_symbol_type = sym.get_st_type();
2691 if (sym.get_st_name() > names_size)
2692 info->enclosing_symbol_name = "(invalid)";
2695 info->enclosing_symbol_name = symbol_names + sym.get_st_name();
2696 if (parameters->options().do_demangle())
2698 char* demangled_name = cplus_demangle(
2699 info->enclosing_symbol_name.c_str(),
2700 DMGL_ANSI | DMGL_PARAMS);
2701 if (demangled_name != NULL)
2703 info->enclosing_symbol_name.assign(demangled_name);
2704 free(demangled_name);
2715 // Look for a kept section corresponding to the given discarded section,
2716 // and return its output address. This is used only for relocations in
2717 // debugging sections. If we can't find the kept section, return 0.
2719 template<int size, bool big_endian>
2720 typename Sized_relobj_file<size, big_endian>::Address
2721 Sized_relobj_file<size, big_endian>::map_to_kept_section(
2725 Relobj* kept_object;
2726 unsigned int kept_shndx;
2727 if (this->get_kept_comdat_section(shndx, &kept_object, &kept_shndx))
2729 Sized_relobj_file<size, big_endian>* kept_relobj =
2730 static_cast<Sized_relobj_file<size, big_endian>*>(kept_object);
2731 Output_section* os = kept_relobj->output_section(kept_shndx);
2732 Address offset = kept_relobj->get_output_section_offset(kept_shndx);
2733 if (os != NULL && offset != invalid_address)
2736 return os->address() + offset;
2743 // Get symbol counts.
2745 template<int size, bool big_endian>
2747 Sized_relobj_file<size, big_endian>::do_get_global_symbol_counts(
2748 const Symbol_table*,
2752 *defined = this->defined_count_;
2754 for (typename Symbols::const_iterator p = this->symbols_.begin();
2755 p != this->symbols_.end();
2758 && (*p)->source() == Symbol::FROM_OBJECT
2759 && (*p)->object() == this
2760 && (*p)->is_defined())
2765 // Return a view of the decompressed contents of a section. Set *PLEN
2766 // to the size. Set *IS_NEW to true if the contents need to be freed
2769 template<int size, bool big_endian>
2770 const unsigned char*
2771 Sized_relobj_file<size, big_endian>::do_decompressed_section_contents(
2773 section_size_type* plen,
2776 section_size_type buffer_size;
2777 const unsigned char* buffer = this->do_section_contents(shndx, &buffer_size,
2780 if (this->compressed_sections_ == NULL)
2782 *plen = buffer_size;
2787 Compressed_section_map::const_iterator p =
2788 this->compressed_sections_->find(shndx);
2789 if (p == this->compressed_sections_->end())
2791 *plen = buffer_size;
2796 section_size_type uncompressed_size = p->second.size;
2797 if (p->second.contents != NULL)
2799 *plen = uncompressed_size;
2801 return p->second.contents;
2804 unsigned char* uncompressed_data = new unsigned char[uncompressed_size];
2805 if (!decompress_input_section(buffer,
2809 this->error(_("could not decompress section %s"),
2810 this->do_section_name(shndx).c_str());
2812 // We could cache the results in p->second.contents and store
2813 // false in *IS_NEW, but build_compressed_section_map() would
2814 // have done so if it had expected it to be profitable. If
2815 // we reach this point, we expect to need the contents only
2816 // once in this pass.
2817 *plen = uncompressed_size;
2819 return uncompressed_data;
2822 // Discard any buffers of uncompressed sections. This is done
2823 // at the end of the Add_symbols task.
2825 template<int size, bool big_endian>
2827 Sized_relobj_file<size, big_endian>::do_discard_decompressed_sections()
2829 if (this->compressed_sections_ == NULL)
2832 for (Compressed_section_map::iterator p = this->compressed_sections_->begin();
2833 p != this->compressed_sections_->end();
2836 if (p->second.contents != NULL)
2838 delete[] p->second.contents;
2839 p->second.contents = NULL;
2844 // Input_objects methods.
2846 // Add a regular relocatable object to the list. Return false if this
2847 // object should be ignored.
2850 Input_objects::add_object(Object* obj)
2852 // Print the filename if the -t/--trace option is selected.
2853 if (parameters->options().trace())
2854 gold_info("%s", obj->name().c_str());
2856 if (!obj->is_dynamic())
2857 this->relobj_list_.push_back(static_cast<Relobj*>(obj));
2860 // See if this is a duplicate SONAME.
2861 Dynobj* dynobj = static_cast<Dynobj*>(obj);
2862 const char* soname = dynobj->soname();
2864 std::pair<Unordered_set<std::string>::iterator, bool> ins =
2865 this->sonames_.insert(soname);
2868 // We have already seen a dynamic object with this soname.
2872 this->dynobj_list_.push_back(dynobj);
2875 // Add this object to the cross-referencer if requested.
2876 if (parameters->options().user_set_print_symbol_counts()
2877 || parameters->options().cref())
2879 if (this->cref_ == NULL)
2880 this->cref_ = new Cref();
2881 this->cref_->add_object(obj);
2887 // For each dynamic object, record whether we've seen all of its
2888 // explicit dependencies.
2891 Input_objects::check_dynamic_dependencies() const
2893 bool issued_copy_dt_needed_error = false;
2894 for (Dynobj_list::const_iterator p = this->dynobj_list_.begin();
2895 p != this->dynobj_list_.end();
2898 const Dynobj::Needed& needed((*p)->needed());
2899 bool found_all = true;
2900 Dynobj::Needed::const_iterator pneeded;
2901 for (pneeded = needed.begin(); pneeded != needed.end(); ++pneeded)
2903 if (this->sonames_.find(*pneeded) == this->sonames_.end())
2909 (*p)->set_has_unknown_needed_entries(!found_all);
2911 // --copy-dt-needed-entries aka --add-needed is a GNU ld option
2912 // that gold does not support. However, they cause no trouble
2913 // unless there is a DT_NEEDED entry that we don't know about;
2914 // warn only in that case.
2916 && !issued_copy_dt_needed_error
2917 && (parameters->options().copy_dt_needed_entries()
2918 || parameters->options().add_needed()))
2920 const char* optname;
2921 if (parameters->options().copy_dt_needed_entries())
2922 optname = "--copy-dt-needed-entries";
2924 optname = "--add-needed";
2925 gold_error(_("%s is not supported but is required for %s in %s"),
2926 optname, (*pneeded).c_str(), (*p)->name().c_str());
2927 issued_copy_dt_needed_error = true;
2932 // Start processing an archive.
2935 Input_objects::archive_start(Archive* archive)
2937 if (parameters->options().user_set_print_symbol_counts()
2938 || parameters->options().cref())
2940 if (this->cref_ == NULL)
2941 this->cref_ = new Cref();
2942 this->cref_->add_archive_start(archive);
2946 // Stop processing an archive.
2949 Input_objects::archive_stop(Archive* archive)
2951 if (parameters->options().user_set_print_symbol_counts()
2952 || parameters->options().cref())
2953 this->cref_->add_archive_stop(archive);
2956 // Print symbol counts
2959 Input_objects::print_symbol_counts(const Symbol_table* symtab) const
2961 if (parameters->options().user_set_print_symbol_counts()
2962 && this->cref_ != NULL)
2963 this->cref_->print_symbol_counts(symtab);
2966 // Print a cross reference table.
2969 Input_objects::print_cref(const Symbol_table* symtab, FILE* f) const
2971 if (parameters->options().cref() && this->cref_ != NULL)
2972 this->cref_->print_cref(symtab, f);
2975 // Relocate_info methods.
2977 // Return a string describing the location of a relocation when file
2978 // and lineno information is not available. This is only used in
2981 template<int size, bool big_endian>
2983 Relocate_info<size, big_endian>::location(size_t, off_t offset) const
2985 Sized_dwarf_line_info<size, big_endian> line_info(this->object);
2986 std::string ret = line_info.addr2line(this->data_shndx, offset, NULL);
2990 ret = this->object->name();
2992 Symbol_location_info info;
2993 if (this->object->get_symbol_location_info(this->data_shndx, offset, &info))
2995 if (!info.source_file.empty())
2998 ret += info.source_file;
3001 if (info.enclosing_symbol_type == elfcpp::STT_FUNC)
3002 ret += _("function ");
3003 ret += info.enclosing_symbol_name;
3008 ret += this->object->section_name(this->data_shndx);
3010 snprintf(buf, sizeof buf, "+0x%lx)", static_cast<long>(offset));
3015 } // End namespace gold.
3020 using namespace gold;
3022 // Read an ELF file with the header and return the appropriate
3023 // instance of Object.
3025 template<int size, bool big_endian>
3027 make_elf_sized_object(const std::string& name, Input_file* input_file,
3028 off_t offset, const elfcpp::Ehdr<size, big_endian>& ehdr,
3029 bool* punconfigured)
3031 Target* target = select_target(input_file, offset,
3032 ehdr.get_e_machine(), size, big_endian,
3033 ehdr.get_e_ident()[elfcpp::EI_OSABI],
3034 ehdr.get_e_ident()[elfcpp::EI_ABIVERSION]);
3036 gold_fatal(_("%s: unsupported ELF machine number %d"),
3037 name.c_str(), ehdr.get_e_machine());
3039 if (!parameters->target_valid())
3040 set_parameters_target(target);
3041 else if (target != ¶meters->target())
3043 if (punconfigured != NULL)
3044 *punconfigured = true;
3046 gold_error(_("%s: incompatible target"), name.c_str());
3050 return target->make_elf_object<size, big_endian>(name, input_file, offset,
3054 } // End anonymous namespace.
3059 // Return whether INPUT_FILE is an ELF object.
3062 is_elf_object(Input_file* input_file, off_t offset,
3063 const unsigned char** start, int* read_size)
3065 off_t filesize = input_file->file().filesize();
3066 int want = elfcpp::Elf_recognizer::max_header_size;
3067 if (filesize - offset < want)
3068 want = filesize - offset;
3070 const unsigned char* p = input_file->file().get_view(offset, 0, want,
3075 return elfcpp::Elf_recognizer::is_elf_file(p, want);
3078 // Read an ELF file and return the appropriate instance of Object.
3081 make_elf_object(const std::string& name, Input_file* input_file, off_t offset,
3082 const unsigned char* p, section_offset_type bytes,
3083 bool* punconfigured)
3085 if (punconfigured != NULL)
3086 *punconfigured = false;
3089 bool big_endian = false;
3091 if (!elfcpp::Elf_recognizer::is_valid_header(p, bytes, &size,
3092 &big_endian, &error))
3094 gold_error(_("%s: %s"), name.c_str(), error.c_str());
3102 #ifdef HAVE_TARGET_32_BIG
3103 elfcpp::Ehdr<32, true> ehdr(p);
3104 return make_elf_sized_object<32, true>(name, input_file,
3105 offset, ehdr, punconfigured);
3107 if (punconfigured != NULL)
3108 *punconfigured = true;
3110 gold_error(_("%s: not configured to support "
3111 "32-bit big-endian object"),
3118 #ifdef HAVE_TARGET_32_LITTLE
3119 elfcpp::Ehdr<32, false> ehdr(p);
3120 return make_elf_sized_object<32, false>(name, input_file,
3121 offset, ehdr, punconfigured);
3123 if (punconfigured != NULL)
3124 *punconfigured = true;
3126 gold_error(_("%s: not configured to support "
3127 "32-bit little-endian object"),
3133 else if (size == 64)
3137 #ifdef HAVE_TARGET_64_BIG
3138 elfcpp::Ehdr<64, true> ehdr(p);
3139 return make_elf_sized_object<64, true>(name, input_file,
3140 offset, ehdr, punconfigured);
3142 if (punconfigured != NULL)
3143 *punconfigured = true;
3145 gold_error(_("%s: not configured to support "
3146 "64-bit big-endian object"),
3153 #ifdef HAVE_TARGET_64_LITTLE
3154 elfcpp::Ehdr<64, false> ehdr(p);
3155 return make_elf_sized_object<64, false>(name, input_file,
3156 offset, ehdr, punconfigured);
3158 if (punconfigured != NULL)
3159 *punconfigured = true;
3161 gold_error(_("%s: not configured to support "
3162 "64-bit little-endian object"),
3172 // Instantiate the templates we need.
3174 #ifdef HAVE_TARGET_32_LITTLE
3177 Object::read_section_data<32, false>(elfcpp::Elf_file<32, false, Object>*,
3178 Read_symbols_data*);
3180 const unsigned char*
3181 Object::find_shdr<32,false>(const unsigned char*, const char*, const char*,
3182 section_size_type, const unsigned char*) const;
3185 #ifdef HAVE_TARGET_32_BIG
3188 Object::read_section_data<32, true>(elfcpp::Elf_file<32, true, Object>*,
3189 Read_symbols_data*);
3191 const unsigned char*
3192 Object::find_shdr<32,true>(const unsigned char*, const char*, const char*,
3193 section_size_type, const unsigned char*) const;
3196 #ifdef HAVE_TARGET_64_LITTLE
3199 Object::read_section_data<64, false>(elfcpp::Elf_file<64, false, Object>*,
3200 Read_symbols_data*);
3202 const unsigned char*
3203 Object::find_shdr<64,false>(const unsigned char*, const char*, const char*,
3204 section_size_type, const unsigned char*) const;
3207 #ifdef HAVE_TARGET_64_BIG
3210 Object::read_section_data<64, true>(elfcpp::Elf_file<64, true, Object>*,
3211 Read_symbols_data*);
3213 const unsigned char*
3214 Object::find_shdr<64,true>(const unsigned char*, const char*, const char*,
3215 section_size_type, const unsigned char*) const;
3218 #ifdef HAVE_TARGET_32_LITTLE
3220 class Sized_relobj_file<32, false>;
3223 #ifdef HAVE_TARGET_32_BIG
3225 class Sized_relobj_file<32, true>;
3228 #ifdef HAVE_TARGET_64_LITTLE
3230 class Sized_relobj_file<64, false>;
3233 #ifdef HAVE_TARGET_64_BIG
3235 class Sized_relobj_file<64, true>;
3238 #ifdef HAVE_TARGET_32_LITTLE
3240 struct Relocate_info<32, false>;
3243 #ifdef HAVE_TARGET_32_BIG
3245 struct Relocate_info<32, true>;
3248 #ifdef HAVE_TARGET_64_LITTLE
3250 struct Relocate_info<64, false>;
3253 #ifdef HAVE_TARGET_64_BIG
3255 struct Relocate_info<64, true>;
3258 #ifdef HAVE_TARGET_32_LITTLE
3261 Xindex::initialize_symtab_xindex<32, false>(Object*, unsigned int);
3265 Xindex::read_symtab_xindex<32, false>(Object*, unsigned int,
3266 const unsigned char*);
3269 #ifdef HAVE_TARGET_32_BIG
3272 Xindex::initialize_symtab_xindex<32, true>(Object*, unsigned int);
3276 Xindex::read_symtab_xindex<32, true>(Object*, unsigned int,
3277 const unsigned char*);
3280 #ifdef HAVE_TARGET_64_LITTLE
3283 Xindex::initialize_symtab_xindex<64, false>(Object*, unsigned int);
3287 Xindex::read_symtab_xindex<64, false>(Object*, unsigned int,
3288 const unsigned char*);
3291 #ifdef HAVE_TARGET_64_BIG
3294 Xindex::initialize_symtab_xindex<64, true>(Object*, unsigned int);
3298 Xindex::read_symtab_xindex<64, true>(Object*, unsigned int,
3299 const unsigned char*);
3302 } // End namespace gold.