1 // object.cc -- support for an object file for linking in gold
3 // Copyright 2006, 2007 Free Software Foundation, Inc.
4 // Written by Ian Lance Taylor <iant@google.com>.
6 // This file is part of gold.
8 // This program is free software; you can redistribute it and/or modify
9 // it under the terms of the GNU General Public License as published by
10 // the Free Software Foundation; either version 3 of the License, or
11 // (at your option) any later version.
13 // This program is distributed in the hope that it will be useful,
14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 // GNU General Public License for more details.
18 // You should have received a copy of the GNU General Public License
19 // along with this program; if not, write to the Free Software
20 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
21 // MA 02110-1301, USA.
29 #include "libiberty.h"
31 #include "target-select.h"
32 #include "dwarf_reader.h"
45 // Set the target based on fields in the ELF file header.
48 Object::set_target(int machine, int size, bool big_endian, int osabi,
51 Target* target = select_target(machine, size, big_endian, osabi, abiversion);
53 gold_fatal(_("%s: unsupported ELF machine number %d"),
54 this->name().c_str(), machine);
55 this->target_ = target;
58 // Report an error for this object file. This is used by the
59 // elfcpp::Elf_file interface, and also called by the Object code
63 Object::error(const char* format, ...) const
66 va_start(args, format);
68 if (vasprintf(&buf, format, args) < 0)
71 gold_error(_("%s: %s"), this->name().c_str(), buf);
75 // Return a view of the contents of a section.
78 Object::section_contents(unsigned int shndx, off_t* plen, bool cache)
80 Location loc(this->do_section_contents(shndx));
81 *plen = loc.data_size;
82 return this->get_view(loc.file_offset, loc.data_size, cache);
85 // Read the section data into SD. This is code common to Sized_relobj
86 // and Sized_dynobj, so we put it into Object.
88 template<int size, bool big_endian>
90 Object::read_section_data(elfcpp::Elf_file<size, big_endian, Object>* elf_file,
91 Read_symbols_data* sd)
93 const int shdr_size = elfcpp::Elf_sizes<size>::shdr_size;
95 // Read the section headers.
96 const off_t shoff = elf_file->shoff();
97 const unsigned int shnum = this->shnum();
98 sd->section_headers = this->get_lasting_view(shoff, shnum * shdr_size, true);
100 // Read the section names.
101 const unsigned char* pshdrs = sd->section_headers->data();
102 const unsigned char* pshdrnames = pshdrs + elf_file->shstrndx() * shdr_size;
103 typename elfcpp::Shdr<size, big_endian> shdrnames(pshdrnames);
105 if (shdrnames.get_sh_type() != elfcpp::SHT_STRTAB)
106 this->error(_("section name section has wrong type: %u"),
107 static_cast<unsigned int>(shdrnames.get_sh_type()));
109 sd->section_names_size = shdrnames.get_sh_size();
110 sd->section_names = this->get_lasting_view(shdrnames.get_sh_offset(),
111 sd->section_names_size, false);
114 // If NAME is the name of a special .gnu.warning section, arrange for
115 // the warning to be issued. SHNDX is the section index. Return
116 // whether it is a warning section.
119 Object::handle_gnu_warning_section(const char* name, unsigned int shndx,
120 Symbol_table* symtab)
122 const char warn_prefix[] = ".gnu.warning.";
123 const int warn_prefix_len = sizeof warn_prefix - 1;
124 if (strncmp(name, warn_prefix, warn_prefix_len) == 0)
126 symtab->add_warning(name + warn_prefix_len, this, shndx);
132 // Class Sized_relobj.
134 template<int size, bool big_endian>
135 Sized_relobj<size, big_endian>::Sized_relobj(
136 const std::string& name,
137 Input_file* input_file,
139 const elfcpp::Ehdr<size, big_endian>& ehdr)
140 : Relobj(name, input_file, offset),
141 elf_file_(this, ehdr),
143 local_symbol_count_(0),
144 output_local_symbol_count_(0),
146 local_symbol_offset_(0),
148 local_got_offsets_(),
153 template<int size, bool big_endian>
154 Sized_relobj<size, big_endian>::~Sized_relobj()
158 // Set up an object file based on the file header. This sets up the
159 // target and reads the section information.
161 template<int size, bool big_endian>
163 Sized_relobj<size, big_endian>::setup(
164 const elfcpp::Ehdr<size, big_endian>& ehdr)
166 this->set_target(ehdr.get_e_machine(), size, big_endian,
167 ehdr.get_e_ident()[elfcpp::EI_OSABI],
168 ehdr.get_e_ident()[elfcpp::EI_ABIVERSION]);
170 const unsigned int shnum = this->elf_file_.shnum();
171 this->set_shnum(shnum);
174 // Find the SHT_SYMTAB section, given the section headers. The ELF
175 // standard says that maybe in the future there can be more than one
176 // SHT_SYMTAB section. Until somebody figures out how that could
177 // work, we assume there is only one.
179 template<int size, bool big_endian>
181 Sized_relobj<size, big_endian>::find_symtab(const unsigned char* pshdrs)
183 const unsigned int shnum = this->shnum();
184 this->symtab_shndx_ = 0;
187 // Look through the sections in reverse order, since gas tends
188 // to put the symbol table at the end.
189 const unsigned char* p = pshdrs + shnum * This::shdr_size;
190 unsigned int i = shnum;
194 p -= This::shdr_size;
195 typename This::Shdr shdr(p);
196 if (shdr.get_sh_type() == elfcpp::SHT_SYMTAB)
198 this->symtab_shndx_ = i;
205 // Return whether SHDR has the right type and flags to be a GNU
206 // .eh_frame section.
208 template<int size, bool big_endian>
210 Sized_relobj<size, big_endian>::check_eh_frame_flags(
211 const elfcpp::Shdr<size, big_endian>* shdr) const
213 return (shdr->get_sh_size() > 0
214 && shdr->get_sh_type() == elfcpp::SHT_PROGBITS
215 && shdr->get_sh_flags() == elfcpp::SHF_ALLOC);
218 // Return whether there is a GNU .eh_frame section, given the section
219 // headers and the section names.
221 template<int size, bool big_endian>
223 Sized_relobj<size, big_endian>::find_eh_frame(const unsigned char* pshdrs,
225 off_t names_size) const
227 const unsigned int shnum = this->shnum();
228 const unsigned char* p = pshdrs + This::shdr_size;
229 for (unsigned int i = 1; i < shnum; ++i, p += This::shdr_size)
231 typename This::Shdr shdr(p);
232 if (this->check_eh_frame_flags(&shdr))
234 if (shdr.get_sh_name() >= names_size)
236 this->error(_("bad section name offset for section %u: %lu"),
237 i, static_cast<unsigned long>(shdr.get_sh_name()));
241 const char* name = names + shdr.get_sh_name();
242 if (strcmp(name, ".eh_frame") == 0)
249 // Read the sections and symbols from an object file.
251 template<int size, bool big_endian>
253 Sized_relobj<size, big_endian>::do_read_symbols(Read_symbols_data* sd)
255 this->read_section_data(&this->elf_file_, sd);
257 const unsigned char* const pshdrs = sd->section_headers->data();
259 this->find_symtab(pshdrs);
261 const unsigned char* namesu = sd->section_names->data();
262 const char* names = reinterpret_cast<const char*>(namesu);
263 if (this->find_eh_frame(pshdrs, names, sd->section_names_size))
264 this->has_eh_frame_ = true;
267 sd->symbols_size = 0;
268 sd->external_symbols_offset = 0;
269 sd->symbol_names = NULL;
270 sd->symbol_names_size = 0;
272 if (this->symtab_shndx_ == 0)
274 // No symbol table. Weird but legal.
278 // Get the symbol table section header.
279 typename This::Shdr symtabshdr(pshdrs
280 + this->symtab_shndx_ * This::shdr_size);
281 gold_assert(symtabshdr.get_sh_type() == elfcpp::SHT_SYMTAB);
283 // If this object has a .eh_frame section, we need all the symbols.
284 // Otherwise we only need the external symbols. While it would be
285 // simpler to just always read all the symbols, I've seen object
286 // files with well over 2000 local symbols, which for a 64-bit
287 // object file format is over 5 pages that we don't need to read
290 const int sym_size = This::sym_size;
291 const unsigned int loccount = symtabshdr.get_sh_info();
292 this->local_symbol_count_ = loccount;
293 off_t locsize = loccount * sym_size;
294 off_t dataoff = symtabshdr.get_sh_offset();
295 off_t datasize = symtabshdr.get_sh_size();
296 off_t extoff = dataoff + locsize;
297 off_t extsize = datasize - locsize;
299 off_t readoff = this->has_eh_frame_ ? dataoff : extoff;
300 off_t readsize = this->has_eh_frame_ ? datasize : extsize;
302 File_view* fvsymtab = this->get_lasting_view(readoff, readsize, false);
304 // Read the section header for the symbol names.
305 unsigned int strtab_shndx = symtabshdr.get_sh_link();
306 if (strtab_shndx >= this->shnum())
308 this->error(_("invalid symbol table name index: %u"), strtab_shndx);
311 typename This::Shdr strtabshdr(pshdrs + strtab_shndx * This::shdr_size);
312 if (strtabshdr.get_sh_type() != elfcpp::SHT_STRTAB)
314 this->error(_("symbol table name section has wrong type: %u"),
315 static_cast<unsigned int>(strtabshdr.get_sh_type()));
319 // Read the symbol names.
320 File_view* fvstrtab = this->get_lasting_view(strtabshdr.get_sh_offset(),
321 strtabshdr.get_sh_size(), true);
323 sd->symbols = fvsymtab;
324 sd->symbols_size = readsize;
325 sd->external_symbols_offset = this->has_eh_frame_ ? locsize : 0;
326 sd->symbol_names = fvstrtab;
327 sd->symbol_names_size = strtabshdr.get_sh_size();
330 // Return the section index of symbol SYM. Set *VALUE to its value in
331 // the object file. Note that for a symbol which is not defined in
332 // this object file, this will set *VALUE to 0 and return SHN_UNDEF;
333 // it will not return the final value of the symbol in the link.
335 template<int size, bool big_endian>
337 Sized_relobj<size, big_endian>::symbol_section_and_value(unsigned int sym,
341 const unsigned char* symbols = this->section_contents(this->symtab_shndx_,
345 const size_t count = symbols_size / This::sym_size;
346 gold_assert(sym < count);
348 elfcpp::Sym<size, big_endian> elfsym(symbols + sym * This::sym_size);
349 *value = elfsym.get_st_value();
350 // FIXME: Handle SHN_XINDEX.
351 return elfsym.get_st_shndx();
354 // Return whether to include a section group in the link. LAYOUT is
355 // used to keep track of which section groups we have already seen.
356 // INDEX is the index of the section group and SHDR is the section
357 // header. If we do not want to include this group, we set bits in
358 // OMIT for each section which should be discarded.
360 template<int size, bool big_endian>
362 Sized_relobj<size, big_endian>::include_section_group(
365 const elfcpp::Shdr<size, big_endian>& shdr,
366 std::vector<bool>* omit)
368 // Read the section contents.
369 const unsigned char* pcon = this->get_view(shdr.get_sh_offset(),
370 shdr.get_sh_size(), false);
371 const elfcpp::Elf_Word* pword =
372 reinterpret_cast<const elfcpp::Elf_Word*>(pcon);
374 // The first word contains flags. We only care about COMDAT section
375 // groups. Other section groups are always included in the link
376 // just like ordinary sections.
377 elfcpp::Elf_Word flags = elfcpp::Swap<32, big_endian>::readval(pword);
378 if ((flags & elfcpp::GRP_COMDAT) == 0)
381 // Look up the group signature, which is the name of a symbol. This
382 // is a lot of effort to go to to read a string. Why didn't they
383 // just use the name of the SHT_GROUP section as the group
386 // Get the appropriate symbol table header (this will normally be
387 // the single SHT_SYMTAB section, but in principle it need not be).
388 const unsigned int link = shdr.get_sh_link();
389 typename This::Shdr symshdr(this, this->elf_file_.section_header(link));
391 // Read the symbol table entry.
392 if (shdr.get_sh_info() >= symshdr.get_sh_size() / This::sym_size)
394 this->error(_("section group %u info %u out of range"),
395 index, shdr.get_sh_info());
398 off_t symoff = symshdr.get_sh_offset() + shdr.get_sh_info() * This::sym_size;
399 const unsigned char* psym = this->get_view(symoff, This::sym_size, true);
400 elfcpp::Sym<size, big_endian> sym(psym);
402 // Read the symbol table names.
404 const unsigned char* psymnamesu;
405 psymnamesu = this->section_contents(symshdr.get_sh_link(), &symnamelen,
407 const char* psymnames = reinterpret_cast<const char*>(psymnamesu);
409 // Get the section group signature.
410 if (sym.get_st_name() >= symnamelen)
412 this->error(_("symbol %u name offset %u out of range"),
413 shdr.get_sh_info(), sym.get_st_name());
417 const char* signature = psymnames + sym.get_st_name();
419 // It seems that some versions of gas will create a section group
420 // associated with a section symbol, and then fail to give a name to
421 // the section symbol. In such a case, use the name of the section.
424 if (signature[0] == '\0' && sym.get_st_type() == elfcpp::STT_SECTION)
426 secname = this->section_name(sym.get_st_shndx());
427 signature = secname.c_str();
430 // Record this section group, and see whether we've already seen one
431 // with the same signature.
432 if (layout->add_comdat(signature, true))
435 // This is a duplicate. We want to discard the sections in this
437 size_t count = shdr.get_sh_size() / sizeof(elfcpp::Elf_Word);
438 for (size_t i = 1; i < count; ++i)
440 elfcpp::Elf_Word secnum =
441 elfcpp::Swap<32, big_endian>::readval(pword + i);
442 if (secnum >= this->shnum())
444 this->error(_("section %u in section group %u out of range"),
448 (*omit)[secnum] = true;
454 // Whether to include a linkonce section in the link. NAME is the
455 // name of the section and SHDR is the section header.
457 // Linkonce sections are a GNU extension implemented in the original
458 // GNU linker before section groups were defined. The semantics are
459 // that we only include one linkonce section with a given name. The
460 // name of a linkonce section is normally .gnu.linkonce.T.SYMNAME,
461 // where T is the type of section and SYMNAME is the name of a symbol.
462 // In an attempt to make linkonce sections interact well with section
463 // groups, we try to identify SYMNAME and use it like a section group
464 // signature. We want to block section groups with that signature,
465 // but not other linkonce sections with that signature. We also use
466 // the full name of the linkonce section as a normal section group
469 template<int size, bool big_endian>
471 Sized_relobj<size, big_endian>::include_linkonce_section(
474 const elfcpp::Shdr<size, big_endian>&)
476 // In general the symbol name we want will be the string following
477 // the last '.'. However, we have to handle the case of
478 // .gnu.linkonce.t.__i686.get_pc_thunk.bx, which was generated by
479 // some versions of gcc. So we use a heuristic: if the name starts
480 // with ".gnu.linkonce.t.", we use everything after that. Otherwise
481 // we look for the last '.'. We can't always simply skip
482 // ".gnu.linkonce.X", because we have to deal with cases like
483 // ".gnu.linkonce.d.rel.ro.local".
484 const char* const linkonce_t = ".gnu.linkonce.t.";
486 if (strncmp(name, linkonce_t, strlen(linkonce_t)) == 0)
487 symname = name + strlen(linkonce_t);
489 symname = strrchr(name, '.') + 1;
490 bool include1 = layout->add_comdat(symname, false);
491 bool include2 = layout->add_comdat(name, true);
492 return include1 && include2;
495 // Lay out the input sections. We walk through the sections and check
496 // whether they should be included in the link. If they should, we
497 // pass them to the Layout object, which will return an output section
500 template<int size, bool big_endian>
502 Sized_relobj<size, big_endian>::do_layout(Symbol_table* symtab,
504 Read_symbols_data* sd)
506 const unsigned int shnum = this->shnum();
510 // Get the section headers.
511 const unsigned char* pshdrs = sd->section_headers->data();
513 // Get the section names.
514 const unsigned char* pnamesu = sd->section_names->data();
515 const char* pnames = reinterpret_cast<const char*>(pnamesu);
517 // For each section, record the index of the reloc section if any.
518 // Use 0 to mean that there is no reloc section, -1U to mean that
519 // there is more than one.
520 std::vector<unsigned int> reloc_shndx(shnum, 0);
521 std::vector<unsigned int> reloc_type(shnum, elfcpp::SHT_NULL);
522 // Skip the first, dummy, section.
523 pshdrs += This::shdr_size;
524 for (unsigned int i = 1; i < shnum; ++i, pshdrs += This::shdr_size)
526 typename This::Shdr shdr(pshdrs);
528 unsigned int sh_type = shdr.get_sh_type();
529 if (sh_type == elfcpp::SHT_REL || sh_type == elfcpp::SHT_RELA)
531 unsigned int target_shndx = shdr.get_sh_info();
532 if (target_shndx == 0 || target_shndx >= shnum)
534 this->error(_("relocation section %u has bad info %u"),
539 if (reloc_shndx[target_shndx] != 0)
540 reloc_shndx[target_shndx] = -1U;
543 reloc_shndx[target_shndx] = i;
544 reloc_type[target_shndx] = sh_type;
549 std::vector<Map_to_output>& map_sections(this->map_to_output());
550 map_sections.resize(shnum);
552 // Whether we've seen a .note.GNU-stack section.
553 bool seen_gnu_stack = false;
554 // The flags of a .note.GNU-stack section.
555 uint64_t gnu_stack_flags = 0;
557 // Keep track of which sections to omit.
558 std::vector<bool> omit(shnum, false);
560 // Keep track of .eh_frame sections.
561 std::vector<unsigned int> eh_frame_sections;
563 // Skip the first, dummy, section.
564 pshdrs = sd->section_headers->data() + This::shdr_size;
565 for (unsigned int i = 1; i < shnum; ++i, pshdrs += This::shdr_size)
567 typename This::Shdr shdr(pshdrs);
569 if (shdr.get_sh_name() >= sd->section_names_size)
571 this->error(_("bad section name offset for section %u: %lu"),
572 i, static_cast<unsigned long>(shdr.get_sh_name()));
576 const char* name = pnames + shdr.get_sh_name();
578 if (this->handle_gnu_warning_section(name, i, symtab))
580 if (!parameters->output_is_object())
584 // The .note.GNU-stack section is special. It gives the
585 // protection flags that this object file requires for the stack
587 if (strcmp(name, ".note.GNU-stack") == 0)
589 seen_gnu_stack = true;
590 gnu_stack_flags |= shdr.get_sh_flags();
594 bool discard = omit[i];
597 if (shdr.get_sh_type() == elfcpp::SHT_GROUP)
599 if (!this->include_section_group(layout, i, shdr, &omit))
602 else if ((shdr.get_sh_flags() & elfcpp::SHF_GROUP) == 0
603 && Layout::is_linkonce(name))
605 if (!this->include_linkonce_section(layout, name, shdr))
612 // Do not include this section in the link.
613 map_sections[i].output_section = NULL;
617 // The .eh_frame section is special. It holds exception frame
618 // information that we need to read in order to generate the
619 // exception frame header. We process these after all the other
620 // sections so that the exception frame reader can reliably
621 // determine which sections are being discarded, and discard the
622 // corresponding information.
623 if (!parameters->output_is_object()
624 && strcmp(name, ".eh_frame") == 0
625 && this->check_eh_frame_flags(&shdr))
627 eh_frame_sections.push_back(i);
632 Output_section* os = layout->layout(this, i, name, shdr,
633 reloc_shndx[i], reloc_type[i],
636 map_sections[i].output_section = os;
637 map_sections[i].offset = offset;
639 // If this section requires special handling, and if there are
640 // relocs that apply to it, then we must do the special handling
641 // before we apply the relocs.
642 if (offset == -1 && reloc_shndx[i] != 0)
643 this->set_relocs_must_follow_section_writes();
646 layout->layout_gnu_stack(seen_gnu_stack, gnu_stack_flags);
648 // Handle the .eh_frame sections at the end.
649 for (std::vector<unsigned int>::const_iterator p = eh_frame_sections.begin();
650 p != eh_frame_sections.end();
653 gold_assert(this->has_eh_frame_);
654 gold_assert(sd->external_symbols_offset != 0);
657 const unsigned char *pshdr;
658 pshdr = sd->section_headers->data() + i * This::shdr_size;
659 typename This::Shdr shdr(pshdr);
662 Output_section* os = layout->layout_eh_frame(this,
665 sd->symbol_names->data(),
666 sd->symbol_names_size,
671 map_sections[i].output_section = os;
672 map_sections[i].offset = offset;
674 // If this section requires special handling, and if there are
675 // relocs that apply to it, then we must do the special handling
676 // before we apply the relocs.
677 if (offset == -1 && reloc_shndx[i] != 0)
678 this->set_relocs_must_follow_section_writes();
681 delete sd->section_headers;
682 sd->section_headers = NULL;
683 delete sd->section_names;
684 sd->section_names = NULL;
687 // Add the symbols to the symbol table.
689 template<int size, bool big_endian>
691 Sized_relobj<size, big_endian>::do_add_symbols(Symbol_table* symtab,
692 Read_symbols_data* sd)
694 if (sd->symbols == NULL)
696 gold_assert(sd->symbol_names == NULL);
700 const int sym_size = This::sym_size;
701 size_t symcount = ((sd->symbols_size - sd->external_symbols_offset)
703 if (static_cast<off_t>(symcount * sym_size)
704 != sd->symbols_size - sd->external_symbols_offset)
706 this->error(_("size of symbols is not multiple of symbol size"));
710 this->symbols_.resize(symcount);
712 const char* sym_names =
713 reinterpret_cast<const char*>(sd->symbol_names->data());
714 symtab->add_from_relobj(this,
715 sd->symbols->data() + sd->external_symbols_offset,
716 symcount, sym_names, sd->symbol_names_size,
721 delete sd->symbol_names;
722 sd->symbol_names = NULL;
725 // Finalize the local symbols. Here we record the file offset at
726 // which they should be output, we add their names to *POOL, and we
727 // add their values to THIS->LOCAL_VALUES_. Return the symbol index.
728 // This function is always called from the main thread. The actual
729 // output of the local symbols will occur in a separate task.
731 template<int size, bool big_endian>
733 Sized_relobj<size, big_endian>::do_finalize_local_symbols(unsigned int index,
737 gold_assert(this->symtab_shndx_ != -1U);
738 if (this->symtab_shndx_ == 0)
740 // This object has no symbols. Weird but legal.
744 gold_assert(off == static_cast<off_t>(align_address(off, size >> 3)));
746 this->local_symbol_offset_ = off;
748 // Read the symbol table section header.
749 const unsigned int symtab_shndx = this->symtab_shndx_;
750 typename This::Shdr symtabshdr(this,
751 this->elf_file_.section_header(symtab_shndx));
752 gold_assert(symtabshdr.get_sh_type() == elfcpp::SHT_SYMTAB);
754 // Read the local symbols.
755 const int sym_size = This::sym_size;
756 const unsigned int loccount = this->local_symbol_count_;
757 gold_assert(loccount == symtabshdr.get_sh_info());
758 off_t locsize = loccount * sym_size;
759 const unsigned char* psyms = this->get_view(symtabshdr.get_sh_offset(),
762 this->local_values_.resize(loccount);
764 // Read the symbol names.
765 const unsigned int strtab_shndx = symtabshdr.get_sh_link();
767 const unsigned char* pnamesu = this->section_contents(strtab_shndx,
770 const char* pnames = reinterpret_cast<const char*>(pnamesu);
772 // Loop over the local symbols.
774 const std::vector<Map_to_output>& mo(this->map_to_output());
775 unsigned int shnum = this->shnum();
776 unsigned int count = 0;
777 // Skip the first, dummy, symbol.
779 for (unsigned int i = 1; i < loccount; ++i, psyms += sym_size)
781 elfcpp::Sym<size, big_endian> sym(psyms);
783 Symbol_value<size>& lv(this->local_values_[i]);
785 unsigned int shndx = sym.get_st_shndx();
786 lv.set_input_shndx(shndx);
788 if (sym.get_st_type() == elfcpp::STT_SECTION)
789 lv.set_is_section_symbol();
791 if (shndx >= elfcpp::SHN_LORESERVE)
793 if (shndx == elfcpp::SHN_ABS)
794 lv.set_output_value(sym.get_st_value());
797 // FIXME: Handle SHN_XINDEX.
798 this->error(_("unknown section index %u for local symbol %u"),
800 lv.set_output_value(0);
807 this->error(_("local symbol %u section index %u out of range"),
812 Output_section* os = mo[shndx].output_section;
816 lv.set_output_value(0);
817 lv.set_no_output_symtab_entry();
821 if (mo[shndx].offset == -1)
822 lv.set_input_value(sym.get_st_value());
824 lv.set_output_value(mo[shndx].output_section->address()
826 + sym.get_st_value());
829 // Decide whether this symbol should go into the output file.
831 if (sym.get_st_type() == elfcpp::STT_SECTION)
833 lv.set_no_output_symtab_entry();
837 if (sym.get_st_name() >= strtab_size)
839 this->error(_("local symbol %u section name out of range: %u >= %u"),
840 i, sym.get_st_name(),
841 static_cast<unsigned int>(strtab_size));
842 lv.set_no_output_symtab_entry();
846 const char* name = pnames + sym.get_st_name();
847 pool->add(name, true, NULL);
848 lv.set_output_symtab_index(index);
853 this->output_local_symbol_count_ = count;
858 // Return the value of the local symbol symndx.
859 template<int size, bool big_endian>
860 typename elfcpp::Elf_types<size>::Elf_Addr
861 Sized_relobj<size, big_endian>::local_symbol_value(unsigned int symndx) const
863 gold_assert(symndx < this->local_symbol_count_);
864 gold_assert(symndx < this->local_values_.size());
865 const Symbol_value<size>& lv(this->local_values_[symndx]);
866 return lv.value(this, 0);
869 // Return the value of a local symbol defined in input section SHNDX,
870 // with value VALUE, adding addend ADDEND. IS_SECTION_SYMBOL
871 // indicates whether the symbol is a section symbol. This handles
872 // SHF_MERGE sections.
873 template<int size, bool big_endian>
874 typename elfcpp::Elf_types<size>::Elf_Addr
875 Sized_relobj<size, big_endian>::local_value(unsigned int shndx,
877 bool is_section_symbol,
878 Address addend) const
880 const std::vector<Map_to_output>& mo(this->map_to_output());
881 Output_section* os = mo[shndx].output_section;
884 gold_assert(mo[shndx].offset == -1);
886 // Do the mapping required by the output section. If this is not a
887 // section symbol, then we want to map the symbol value, and then
888 // include the addend. If this is a section symbol, then we need to
889 // include the addend to figure out where in the section we are,
890 // before we do the mapping. This will do the right thing provided
891 // the assembler is careful to only convert a relocation in a merged
892 // section to a section symbol if there is a zero addend. If the
893 // assembler does not do this, then in general we can't know what to
894 // do, because we can't distinguish the addend for the instruction
895 // format from the addend for the section offset.
897 if (is_section_symbol)
898 return os->output_address(this, shndx, value + addend);
900 return addend + os->output_address(this, shndx, value);
903 // Write out the local symbols.
905 template<int size, bool big_endian>
907 Sized_relobj<size, big_endian>::write_local_symbols(Output_file* of,
908 const Stringpool* sympool)
910 if (parameters->strip_all())
913 gold_assert(this->symtab_shndx_ != -1U);
914 if (this->symtab_shndx_ == 0)
916 // This object has no symbols. Weird but legal.
920 // Read the symbol table section header.
921 const unsigned int symtab_shndx = this->symtab_shndx_;
922 typename This::Shdr symtabshdr(this,
923 this->elf_file_.section_header(symtab_shndx));
924 gold_assert(symtabshdr.get_sh_type() == elfcpp::SHT_SYMTAB);
925 const unsigned int loccount = this->local_symbol_count_;
926 gold_assert(loccount == symtabshdr.get_sh_info());
928 // Read the local symbols.
929 const int sym_size = This::sym_size;
930 off_t locsize = loccount * sym_size;
931 const unsigned char* psyms = this->get_view(symtabshdr.get_sh_offset(),
934 // Read the symbol names.
935 const unsigned int strtab_shndx = symtabshdr.get_sh_link();
937 const unsigned char* pnamesu = this->section_contents(strtab_shndx,
940 const char* pnames = reinterpret_cast<const char*>(pnamesu);
942 // Get a view into the output file.
943 off_t output_size = this->output_local_symbol_count_ * sym_size;
944 unsigned char* oview = of->get_output_view(this->local_symbol_offset_,
947 const std::vector<Map_to_output>& mo(this->map_to_output());
949 gold_assert(this->local_values_.size() == loccount);
951 unsigned char* ov = oview;
953 for (unsigned int i = 1; i < loccount; ++i, psyms += sym_size)
955 elfcpp::Sym<size, big_endian> isym(psyms);
957 if (!this->local_values_[i].needs_output_symtab_entry())
960 unsigned int st_shndx = isym.get_st_shndx();
961 if (st_shndx < elfcpp::SHN_LORESERVE)
963 gold_assert(st_shndx < mo.size());
964 if (mo[st_shndx].output_section == NULL)
966 st_shndx = mo[st_shndx].output_section->out_shndx();
969 elfcpp::Sym_write<size, big_endian> osym(ov);
971 gold_assert(isym.get_st_name() < strtab_size);
972 const char* name = pnames + isym.get_st_name();
973 osym.put_st_name(sympool->get_offset(name));
974 osym.put_st_value(this->local_values_[i].value(this, 0));
975 osym.put_st_size(isym.get_st_size());
976 osym.put_st_info(isym.get_st_info());
977 osym.put_st_other(isym.get_st_other());
978 osym.put_st_shndx(st_shndx);
983 gold_assert(ov - oview == output_size);
985 of->write_output_view(this->local_symbol_offset_, output_size, oview);
988 // Set *INFO to symbolic information about the offset OFFSET in the
989 // section SHNDX. Return true if we found something, false if we
992 template<int size, bool big_endian>
994 Sized_relobj<size, big_endian>::get_symbol_location_info(
997 Symbol_location_info* info)
999 if (this->symtab_shndx_ == 0)
1003 const unsigned char* symbols = this->section_contents(this->symtab_shndx_,
1007 unsigned int symbol_names_shndx = this->section_link(this->symtab_shndx_);
1009 const unsigned char* symbol_names_u =
1010 this->section_contents(symbol_names_shndx, &names_size, false);
1011 const char* symbol_names = reinterpret_cast<const char*>(symbol_names_u);
1013 const int sym_size = This::sym_size;
1014 const size_t count = symbols_size / sym_size;
1016 const unsigned char* p = symbols;
1017 for (size_t i = 0; i < count; ++i, p += sym_size)
1019 elfcpp::Sym<size, big_endian> sym(p);
1021 if (sym.get_st_type() == elfcpp::STT_FILE)
1023 if (sym.get_st_name() >= names_size)
1024 info->source_file = "(invalid)";
1026 info->source_file = symbol_names + sym.get_st_name();
1028 else if (sym.get_st_shndx() == shndx
1029 && static_cast<off_t>(sym.get_st_value()) <= offset
1030 && (static_cast<off_t>(sym.get_st_value() + sym.get_st_size())
1033 if (sym.get_st_name() > names_size)
1034 info->enclosing_symbol_name = "(invalid)";
1037 info->enclosing_symbol_name = symbol_names + sym.get_st_name();
1038 if (parameters->demangle())
1040 char* demangled_name = cplus_demangle(
1041 info->enclosing_symbol_name.c_str(),
1042 DMGL_ANSI | DMGL_PARAMS);
1043 if (demangled_name != NULL)
1045 info->enclosing_symbol_name.assign(demangled_name);
1046 free(demangled_name);
1057 // Input_objects methods.
1059 // Add a regular relocatable object to the list. Return false if this
1060 // object should be ignored.
1063 Input_objects::add_object(Object* obj)
1065 Target* target = obj->target();
1066 if (this->target_ == NULL)
1067 this->target_ = target;
1068 else if (this->target_ != target)
1070 gold_error(_("%s: incompatible target"), obj->name().c_str());
1074 if (!obj->is_dynamic())
1075 this->relobj_list_.push_back(static_cast<Relobj*>(obj));
1078 // See if this is a duplicate SONAME.
1079 Dynobj* dynobj = static_cast<Dynobj*>(obj);
1080 const char* soname = dynobj->soname();
1082 std::pair<Unordered_set<std::string>::iterator, bool> ins =
1083 this->sonames_.insert(soname);
1086 // We have already seen a dynamic object with this soname.
1090 this->dynobj_list_.push_back(dynobj);
1092 // If this is -lc, remember the directory in which we found it.
1093 // We use this when issuing warnings about undefined symbols: as
1094 // a heuristic, we don't warn about system libraries found in
1095 // the same directory as -lc.
1096 if (strncmp(soname, "libc.so", 7) == 0)
1098 const char* object_name = dynobj->name().c_str();
1099 const char* base = lbasename(object_name);
1100 if (base != object_name)
1101 this->system_library_directory_.assign(object_name,
1102 base - 1 - object_name);
1106 set_parameters_target(target);
1111 // Return whether an object was found in the system library directory.
1114 Input_objects::found_in_system_library_directory(const Object* object) const
1116 return (!this->system_library_directory_.empty()
1117 && object->name().compare(0,
1118 this->system_library_directory_.size(),
1119 this->system_library_directory_) == 0);
1122 // For each dynamic object, record whether we've seen all of its
1123 // explicit dependencies.
1126 Input_objects::check_dynamic_dependencies() const
1128 for (Dynobj_list::const_iterator p = this->dynobj_list_.begin();
1129 p != this->dynobj_list_.end();
1132 const Dynobj::Needed& needed((*p)->needed());
1133 bool found_all = true;
1134 for (Dynobj::Needed::const_iterator pneeded = needed.begin();
1135 pneeded != needed.end();
1138 if (this->sonames_.find(*pneeded) == this->sonames_.end())
1144 (*p)->set_has_unknown_needed_entries(!found_all);
1148 // Relocate_info methods.
1150 // Return a string describing the location of a relocation. This is
1151 // only used in error messages.
1153 template<int size, bool big_endian>
1155 Relocate_info<size, big_endian>::location(size_t, off_t offset) const
1157 // See if we can get line-number information from debugging sections.
1158 std::string filename;
1159 std::string file_and_lineno; // Better than filename-only, if available.
1161 Sized_dwarf_line_info<size, big_endian> line_info(this->object);
1162 // This will be "" if we failed to parse the debug info for any reason.
1163 file_and_lineno = line_info.addr2line(this->data_shndx, offset);
1165 std::string ret(this->object->name());
1167 Symbol_location_info info;
1168 if (this->object->get_symbol_location_info(this->data_shndx, offset, &info))
1170 ret += " in function ";
1171 ret += info.enclosing_symbol_name;
1173 filename = info.source_file;
1176 if (!file_and_lineno.empty())
1177 ret += file_and_lineno;
1180 if (!filename.empty())
1183 ret += this->object->section_name(this->data_shndx);
1185 // Offsets into sections have to be positive.
1186 snprintf(buf, sizeof(buf), "+0x%lx", static_cast<long>(offset));
1193 } // End namespace gold.
1198 using namespace gold;
1200 // Read an ELF file with the header and return the appropriate
1201 // instance of Object.
1203 template<int size, bool big_endian>
1205 make_elf_sized_object(const std::string& name, Input_file* input_file,
1206 off_t offset, const elfcpp::Ehdr<size, big_endian>& ehdr)
1208 int et = ehdr.get_e_type();
1209 if (et == elfcpp::ET_REL)
1211 Sized_relobj<size, big_endian>* obj =
1212 new Sized_relobj<size, big_endian>(name, input_file, offset, ehdr);
1216 else if (et == elfcpp::ET_DYN)
1218 Sized_dynobj<size, big_endian>* obj =
1219 new Sized_dynobj<size, big_endian>(name, input_file, offset, ehdr);
1225 gold_error(_("%s: unsupported ELF file type %d"),
1231 } // End anonymous namespace.
1236 // Read an ELF file and return the appropriate instance of Object.
1239 make_elf_object(const std::string& name, Input_file* input_file, off_t offset,
1240 const unsigned char* p, off_t bytes)
1242 if (bytes < elfcpp::EI_NIDENT)
1244 gold_error(_("%s: ELF file too short"), name.c_str());
1248 int v = p[elfcpp::EI_VERSION];
1249 if (v != elfcpp::EV_CURRENT)
1251 if (v == elfcpp::EV_NONE)
1252 gold_error(_("%s: invalid ELF version 0"), name.c_str());
1254 gold_error(_("%s: unsupported ELF version %d"), name.c_str(), v);
1258 int c = p[elfcpp::EI_CLASS];
1259 if (c == elfcpp::ELFCLASSNONE)
1261 gold_error(_("%s: invalid ELF class 0"), name.c_str());
1264 else if (c != elfcpp::ELFCLASS32
1265 && c != elfcpp::ELFCLASS64)
1267 gold_error(_("%s: unsupported ELF class %d"), name.c_str(), c);
1271 int d = p[elfcpp::EI_DATA];
1272 if (d == elfcpp::ELFDATANONE)
1274 gold_error(_("%s: invalid ELF data encoding"), name.c_str());
1277 else if (d != elfcpp::ELFDATA2LSB
1278 && d != elfcpp::ELFDATA2MSB)
1280 gold_error(_("%s: unsupported ELF data encoding %d"), name.c_str(), d);
1284 bool big_endian = d == elfcpp::ELFDATA2MSB;
1286 if (c == elfcpp::ELFCLASS32)
1288 if (bytes < elfcpp::Elf_sizes<32>::ehdr_size)
1290 gold_error(_("%s: ELF file too short"), name.c_str());
1295 #ifdef HAVE_TARGET_32_BIG
1296 elfcpp::Ehdr<32, true> ehdr(p);
1297 return make_elf_sized_object<32, true>(name, input_file,
1300 gold_error(_("%s: not configured to support "
1301 "32-bit big-endian object"),
1308 #ifdef HAVE_TARGET_32_LITTLE
1309 elfcpp::Ehdr<32, false> ehdr(p);
1310 return make_elf_sized_object<32, false>(name, input_file,
1313 gold_error(_("%s: not configured to support "
1314 "32-bit little-endian object"),
1322 if (bytes < elfcpp::Elf_sizes<32>::ehdr_size)
1324 gold_error(_("%s: ELF file too short"), name.c_str());
1329 #ifdef HAVE_TARGET_64_BIG
1330 elfcpp::Ehdr<64, true> ehdr(p);
1331 return make_elf_sized_object<64, true>(name, input_file,
1334 gold_error(_("%s: not configured to support "
1335 "64-bit big-endian object"),
1342 #ifdef HAVE_TARGET_64_LITTLE
1343 elfcpp::Ehdr<64, false> ehdr(p);
1344 return make_elf_sized_object<64, false>(name, input_file,
1347 gold_error(_("%s: not configured to support "
1348 "64-bit little-endian object"),
1356 // Instantiate the templates we need. We could use the configure
1357 // script to restrict this to only the ones for implemented targets.
1359 #ifdef HAVE_TARGET_32_LITTLE
1361 class Sized_relobj<32, false>;
1364 #ifdef HAVE_TARGET_32_BIG
1366 class Sized_relobj<32, true>;
1369 #ifdef HAVE_TARGET_64_LITTLE
1371 class Sized_relobj<64, false>;
1374 #ifdef HAVE_TARGET_64_BIG
1376 class Sized_relobj<64, true>;
1379 #ifdef HAVE_TARGET_32_LITTLE
1381 struct Relocate_info<32, false>;
1384 #ifdef HAVE_TARGET_32_BIG
1386 struct Relocate_info<32, true>;
1389 #ifdef HAVE_TARGET_64_LITTLE
1391 struct Relocate_info<64, false>;
1394 #ifdef HAVE_TARGET_64_BIG
1396 struct Relocate_info<64, true>;
1399 } // End namespace gold.