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.
28 #include "libiberty.h"
30 #include "target-select.h"
31 #include "dwarf_reader.h"
44 // Set the target based on fields in the ELF file header.
47 Object::set_target(int machine
, int size
, bool big_endian
, int osabi
,
50 Target
* target
= select_target(machine
, size
, big_endian
, osabi
, abiversion
);
52 gold_fatal(_("%s: unsupported ELF machine number %d"),
53 this->name().c_str(), machine
);
54 this->target_
= target
;
57 // Report an error for this object file. This is used by the
58 // elfcpp::Elf_file interface, and also called by the Object code
62 Object::error(const char* format
, ...) const
65 va_start(args
, format
);
67 if (vasprintf(&buf
, format
, args
) < 0)
70 gold_error(_("%s: %s"), this->name().c_str(), buf
);
74 // Return a view of the contents of a section.
77 Object::section_contents(unsigned int shndx
, off_t
* plen
, bool cache
)
79 Location
loc(this->do_section_contents(shndx
));
80 *plen
= loc
.data_size
;
81 return this->get_view(loc
.file_offset
, loc
.data_size
, cache
);
84 // Read the section data into SD. This is code common to Sized_relobj
85 // and Sized_dynobj, so we put it into Object.
87 template<int size
, bool big_endian
>
89 Object::read_section_data(elfcpp::Elf_file
<size
, big_endian
, Object
>* elf_file
,
90 Read_symbols_data
* sd
)
92 const int shdr_size
= elfcpp::Elf_sizes
<size
>::shdr_size
;
94 // Read the section headers.
95 const off_t shoff
= elf_file
->shoff();
96 const unsigned int shnum
= this->shnum();
97 sd
->section_headers
= this->get_lasting_view(shoff
, shnum
* shdr_size
, true);
99 // Read the section names.
100 const unsigned char* pshdrs
= sd
->section_headers
->data();
101 const unsigned char* pshdrnames
= pshdrs
+ elf_file
->shstrndx() * shdr_size
;
102 typename
elfcpp::Shdr
<size
, big_endian
> shdrnames(pshdrnames
);
104 if (shdrnames
.get_sh_type() != elfcpp::SHT_STRTAB
)
105 this->error(_("section name section has wrong type: %u"),
106 static_cast<unsigned int>(shdrnames
.get_sh_type()));
108 sd
->section_names_size
= shdrnames
.get_sh_size();
109 sd
->section_names
= this->get_lasting_view(shdrnames
.get_sh_offset(),
110 sd
->section_names_size
, false);
113 // If NAME is the name of a special .gnu.warning section, arrange for
114 // the warning to be issued. SHNDX is the section index. Return
115 // whether it is a warning section.
118 Object::handle_gnu_warning_section(const char* name
, unsigned int shndx
,
119 Symbol_table
* symtab
)
121 const char warn_prefix
[] = ".gnu.warning.";
122 const int warn_prefix_len
= sizeof warn_prefix
- 1;
123 if (strncmp(name
, warn_prefix
, warn_prefix_len
) == 0)
125 symtab
->add_warning(name
+ warn_prefix_len
, this, shndx
);
131 // Class Sized_relobj.
133 template<int size
, bool big_endian
>
134 Sized_relobj
<size
, big_endian
>::Sized_relobj(
135 const std::string
& name
,
136 Input_file
* input_file
,
138 const elfcpp::Ehdr
<size
, big_endian
>& ehdr
)
139 : Relobj(name
, input_file
, offset
),
140 elf_file_(this, ehdr
),
142 local_symbol_count_(0),
143 output_local_symbol_count_(0),
145 local_symbol_offset_(0),
147 local_got_offsets_(),
152 template<int size
, bool big_endian
>
153 Sized_relobj
<size
, big_endian
>::~Sized_relobj()
157 // Set up an object file based on the file header. This sets up the
158 // target and reads the section information.
160 template<int size
, bool big_endian
>
162 Sized_relobj
<size
, big_endian
>::setup(
163 const elfcpp::Ehdr
<size
, big_endian
>& ehdr
)
165 this->set_target(ehdr
.get_e_machine(), size
, big_endian
,
166 ehdr
.get_e_ident()[elfcpp::EI_OSABI
],
167 ehdr
.get_e_ident()[elfcpp::EI_ABIVERSION
]);
169 const unsigned int shnum
= this->elf_file_
.shnum();
170 this->set_shnum(shnum
);
173 // Find the SHT_SYMTAB section, given the section headers. The ELF
174 // standard says that maybe in the future there can be more than one
175 // SHT_SYMTAB section. Until somebody figures out how that could
176 // work, we assume there is only one.
178 template<int size
, bool big_endian
>
180 Sized_relobj
<size
, big_endian
>::find_symtab(const unsigned char* pshdrs
)
182 const unsigned int shnum
= this->shnum();
183 this->symtab_shndx_
= 0;
186 // Look through the sections in reverse order, since gas tends
187 // to put the symbol table at the end.
188 const unsigned char* p
= pshdrs
+ shnum
* This::shdr_size
;
189 unsigned int i
= shnum
;
193 p
-= This::shdr_size
;
194 typename
This::Shdr
shdr(p
);
195 if (shdr
.get_sh_type() == elfcpp::SHT_SYMTAB
)
197 this->symtab_shndx_
= i
;
204 // Return whether SHDR has the right type and flags to be a GNU
205 // .eh_frame section.
207 template<int size
, bool big_endian
>
209 Sized_relobj
<size
, big_endian
>::check_eh_frame_flags(
210 const elfcpp::Shdr
<size
, big_endian
>* shdr
) const
212 return (shdr
->get_sh_size() > 0
213 && shdr
->get_sh_type() == elfcpp::SHT_PROGBITS
214 && shdr
->get_sh_flags() == elfcpp::SHF_ALLOC
);
217 // Return whether there is a GNU .eh_frame section, given the section
218 // headers and the section names.
220 template<int size
, bool big_endian
>
222 Sized_relobj
<size
, big_endian
>::find_eh_frame(const unsigned char* pshdrs
,
224 off_t names_size
) const
226 const unsigned int shnum
= this->shnum();
227 const unsigned char* p
= pshdrs
+ This::shdr_size
;
228 for (unsigned int i
= 1; i
< shnum
; ++i
, p
+= This::shdr_size
)
230 typename
This::Shdr
shdr(p
);
231 if (this->check_eh_frame_flags(&shdr
))
233 if (shdr
.get_sh_name() >= names_size
)
235 this->error(_("bad section name offset for section %u: %lu"),
236 i
, static_cast<unsigned long>(shdr
.get_sh_name()));
240 const char* name
= names
+ shdr
.get_sh_name();
241 if (strcmp(name
, ".eh_frame") == 0)
248 // Read the sections and symbols from an object file.
250 template<int size
, bool big_endian
>
252 Sized_relobj
<size
, big_endian
>::do_read_symbols(Read_symbols_data
* sd
)
254 this->read_section_data(&this->elf_file_
, sd
);
256 const unsigned char* const pshdrs
= sd
->section_headers
->data();
258 this->find_symtab(pshdrs
);
260 const unsigned char* namesu
= sd
->section_names
->data();
261 const char* names
= reinterpret_cast<const char*>(namesu
);
262 if (this->find_eh_frame(pshdrs
, names
, sd
->section_names_size
))
263 this->has_eh_frame_
= true;
266 sd
->symbols_size
= 0;
267 sd
->external_symbols_offset
= 0;
268 sd
->symbol_names
= NULL
;
269 sd
->symbol_names_size
= 0;
271 if (this->symtab_shndx_
== 0)
273 // No symbol table. Weird but legal.
277 // Get the symbol table section header.
278 typename
This::Shdr
symtabshdr(pshdrs
279 + this->symtab_shndx_
* This::shdr_size
);
280 gold_assert(symtabshdr
.get_sh_type() == elfcpp::SHT_SYMTAB
);
282 // If this object has a .eh_frame section, we need all the symbols.
283 // Otherwise we only need the external symbols. While it would be
284 // simpler to just always read all the symbols, I've seen object
285 // files with well over 2000 local symbols, which for a 64-bit
286 // object file format is over 5 pages that we don't need to read
289 const int sym_size
= This::sym_size
;
290 const unsigned int loccount
= symtabshdr
.get_sh_info();
291 this->local_symbol_count_
= loccount
;
292 off_t locsize
= loccount
* sym_size
;
293 off_t dataoff
= symtabshdr
.get_sh_offset();
294 off_t datasize
= symtabshdr
.get_sh_size();
295 off_t extoff
= dataoff
+ locsize
;
296 off_t extsize
= datasize
- locsize
;
298 off_t readoff
= this->has_eh_frame_
? dataoff
: extoff
;
299 off_t readsize
= this->has_eh_frame_
? datasize
: extsize
;
301 File_view
* fvsymtab
= this->get_lasting_view(readoff
, readsize
, false);
303 // Read the section header for the symbol names.
304 unsigned int strtab_shndx
= symtabshdr
.get_sh_link();
305 if (strtab_shndx
>= this->shnum())
307 this->error(_("invalid symbol table name index: %u"), strtab_shndx
);
310 typename
This::Shdr
strtabshdr(pshdrs
+ strtab_shndx
* This::shdr_size
);
311 if (strtabshdr
.get_sh_type() != elfcpp::SHT_STRTAB
)
313 this->error(_("symbol table name section has wrong type: %u"),
314 static_cast<unsigned int>(strtabshdr
.get_sh_type()));
318 // Read the symbol names.
319 File_view
* fvstrtab
= this->get_lasting_view(strtabshdr
.get_sh_offset(),
320 strtabshdr
.get_sh_size(), true);
322 sd
->symbols
= fvsymtab
;
323 sd
->symbols_size
= readsize
;
324 sd
->external_symbols_offset
= this->has_eh_frame_
? locsize
: 0;
325 sd
->symbol_names
= fvstrtab
;
326 sd
->symbol_names_size
= strtabshdr
.get_sh_size();
329 // Return the section index of symbol SYM. Set *VALUE to its value in
330 // the object file. Note that for a symbol which is not defined in
331 // this object file, this will set *VALUE to 0 and return SHN_UNDEF;
332 // it will not return the final value of the symbol in the link.
334 template<int size
, bool big_endian
>
336 Sized_relobj
<size
, big_endian
>::symbol_section_and_value(unsigned int sym
,
340 const unsigned char* symbols
= this->section_contents(this->symtab_shndx_
,
344 const size_t count
= symbols_size
/ This::sym_size
;
345 gold_assert(sym
< count
);
347 elfcpp::Sym
<size
, big_endian
> elfsym(symbols
+ sym
* This::sym_size
);
348 *value
= elfsym
.get_st_value();
349 // FIXME: Handle SHN_XINDEX.
350 return elfsym
.get_st_shndx();
353 // Return whether to include a section group in the link. LAYOUT is
354 // used to keep track of which section groups we have already seen.
355 // INDEX is the index of the section group and SHDR is the section
356 // header. If we do not want to include this group, we set bits in
357 // OMIT for each section which should be discarded.
359 template<int size
, bool big_endian
>
361 Sized_relobj
<size
, big_endian
>::include_section_group(
364 const elfcpp::Shdr
<size
, big_endian
>& shdr
,
365 std::vector
<bool>* omit
)
367 // Read the section contents.
368 const unsigned char* pcon
= this->get_view(shdr
.get_sh_offset(),
369 shdr
.get_sh_size(), false);
370 const elfcpp::Elf_Word
* pword
=
371 reinterpret_cast<const elfcpp::Elf_Word
*>(pcon
);
373 // The first word contains flags. We only care about COMDAT section
374 // groups. Other section groups are always included in the link
375 // just like ordinary sections.
376 elfcpp::Elf_Word flags
= elfcpp::Swap
<32, big_endian
>::readval(pword
);
377 if ((flags
& elfcpp::GRP_COMDAT
) == 0)
380 // Look up the group signature, which is the name of a symbol. This
381 // is a lot of effort to go to to read a string. Why didn't they
382 // just use the name of the SHT_GROUP section as the group
385 // Get the appropriate symbol table header (this will normally be
386 // the single SHT_SYMTAB section, but in principle it need not be).
387 const unsigned int link
= shdr
.get_sh_link();
388 typename
This::Shdr
symshdr(this, this->elf_file_
.section_header(link
));
390 // Read the symbol table entry.
391 if (shdr
.get_sh_info() >= symshdr
.get_sh_size() / This::sym_size
)
393 this->error(_("section group %u info %u out of range"),
394 index
, shdr
.get_sh_info());
397 off_t symoff
= symshdr
.get_sh_offset() + shdr
.get_sh_info() * This::sym_size
;
398 const unsigned char* psym
= this->get_view(symoff
, This::sym_size
, true);
399 elfcpp::Sym
<size
, big_endian
> sym(psym
);
401 // Read the symbol table names.
403 const unsigned char* psymnamesu
;
404 psymnamesu
= this->section_contents(symshdr
.get_sh_link(), &symnamelen
,
406 const char* psymnames
= reinterpret_cast<const char*>(psymnamesu
);
408 // Get the section group signature.
409 if (sym
.get_st_name() >= symnamelen
)
411 this->error(_("symbol %u name offset %u out of range"),
412 shdr
.get_sh_info(), sym
.get_st_name());
416 const char* signature
= psymnames
+ sym
.get_st_name();
418 // It seems that some versions of gas will create a section group
419 // associated with a section symbol, and then fail to give a name to
420 // the section symbol. In such a case, use the name of the section.
423 if (signature
[0] == '\0' && sym
.get_st_type() == elfcpp::STT_SECTION
)
425 secname
= this->section_name(sym
.get_st_shndx());
426 signature
= secname
.c_str();
429 // Record this section group, and see whether we've already seen one
430 // with the same signature.
431 if (layout
->add_comdat(signature
, true))
434 // This is a duplicate. We want to discard the sections in this
436 size_t count
= shdr
.get_sh_size() / sizeof(elfcpp::Elf_Word
);
437 for (size_t i
= 1; i
< count
; ++i
)
439 elfcpp::Elf_Word secnum
=
440 elfcpp::Swap
<32, big_endian
>::readval(pword
+ i
);
441 if (secnum
>= this->shnum())
443 this->error(_("section %u in section group %u out of range"),
447 (*omit
)[secnum
] = true;
453 // Whether to include a linkonce section in the link. NAME is the
454 // name of the section and SHDR is the section header.
456 // Linkonce sections are a GNU extension implemented in the original
457 // GNU linker before section groups were defined. The semantics are
458 // that we only include one linkonce section with a given name. The
459 // name of a linkonce section is normally .gnu.linkonce.T.SYMNAME,
460 // where T is the type of section and SYMNAME is the name of a symbol.
461 // In an attempt to make linkonce sections interact well with section
462 // groups, we try to identify SYMNAME and use it like a section group
463 // signature. We want to block section groups with that signature,
464 // but not other linkonce sections with that signature. We also use
465 // the full name of the linkonce section as a normal section group
468 template<int size
, bool big_endian
>
470 Sized_relobj
<size
, big_endian
>::include_linkonce_section(
473 const elfcpp::Shdr
<size
, big_endian
>&)
475 // In general the symbol name we want will be the string following
476 // the last '.'. However, we have to handle the case of
477 // .gnu.linkonce.t.__i686.get_pc_thunk.bx, which was generated by
478 // some versions of gcc. So we use a heuristic: if the name starts
479 // with ".gnu.linkonce.t.", we use everything after that. Otherwise
480 // we look for the last '.'. We can't always simply skip
481 // ".gnu.linkonce.X", because we have to deal with cases like
482 // ".gnu.linkonce.d.rel.ro.local".
483 const char* const linkonce_t
= ".gnu.linkonce.t.";
485 if (strncmp(name
, linkonce_t
, strlen(linkonce_t
)) == 0)
486 symname
= name
+ strlen(linkonce_t
);
488 symname
= strrchr(name
, '.') + 1;
489 bool include1
= layout
->add_comdat(symname
, false);
490 bool include2
= layout
->add_comdat(name
, true);
491 return include1
&& include2
;
494 // Lay out the input sections. We walk through the sections and check
495 // whether they should be included in the link. If they should, we
496 // pass them to the Layout object, which will return an output section
499 template<int size
, bool big_endian
>
501 Sized_relobj
<size
, big_endian
>::do_layout(Symbol_table
* symtab
,
503 Read_symbols_data
* sd
)
505 const unsigned int shnum
= this->shnum();
509 // Get the section headers.
510 const unsigned char* pshdrs
= sd
->section_headers
->data();
512 // Get the section names.
513 const unsigned char* pnamesu
= sd
->section_names
->data();
514 const char* pnames
= reinterpret_cast<const char*>(pnamesu
);
516 // For each section, record the index of the reloc section if any.
517 // Use 0 to mean that there is no reloc section, -1U to mean that
518 // there is more than one.
519 std::vector
<unsigned int> reloc_shndx(shnum
, 0);
520 std::vector
<unsigned int> reloc_type(shnum
, elfcpp::SHT_NULL
);
521 // Skip the first, dummy, section.
522 pshdrs
+= This::shdr_size
;
523 for (unsigned int i
= 1; i
< shnum
; ++i
, pshdrs
+= This::shdr_size
)
525 typename
This::Shdr
shdr(pshdrs
);
527 unsigned int sh_type
= shdr
.get_sh_type();
528 if (sh_type
== elfcpp::SHT_REL
|| sh_type
== elfcpp::SHT_RELA
)
530 unsigned int target_shndx
= shdr
.get_sh_info();
531 if (target_shndx
== 0 || target_shndx
>= shnum
)
533 this->error(_("relocation section %u has bad info %u"),
538 if (reloc_shndx
[target_shndx
] != 0)
539 reloc_shndx
[target_shndx
] = -1U;
542 reloc_shndx
[target_shndx
] = i
;
543 reloc_type
[target_shndx
] = sh_type
;
548 std::vector
<Map_to_output
>& map_sections(this->map_to_output());
549 map_sections
.resize(shnum
);
551 // Whether we've seen a .note.GNU-stack section.
552 bool seen_gnu_stack
= false;
553 // The flags of a .note.GNU-stack section.
554 uint64_t gnu_stack_flags
= 0;
556 // Keep track of which sections to omit.
557 std::vector
<bool> omit(shnum
, false);
559 // Keep track of .eh_frame sections.
560 std::vector
<unsigned int> eh_frame_sections
;
562 // Skip the first, dummy, section.
563 pshdrs
= sd
->section_headers
->data() + This::shdr_size
;
564 for (unsigned int i
= 1; i
< shnum
; ++i
, pshdrs
+= This::shdr_size
)
566 typename
This::Shdr
shdr(pshdrs
);
568 if (shdr
.get_sh_name() >= sd
->section_names_size
)
570 this->error(_("bad section name offset for section %u: %lu"),
571 i
, static_cast<unsigned long>(shdr
.get_sh_name()));
575 const char* name
= pnames
+ shdr
.get_sh_name();
577 if (this->handle_gnu_warning_section(name
, i
, symtab
))
579 if (!parameters
->output_is_object())
583 // The .note.GNU-stack section is special. It gives the
584 // protection flags that this object file requires for the stack
586 if (strcmp(name
, ".note.GNU-stack") == 0)
588 seen_gnu_stack
= true;
589 gnu_stack_flags
|= shdr
.get_sh_flags();
593 bool discard
= omit
[i
];
596 if (shdr
.get_sh_type() == elfcpp::SHT_GROUP
)
598 if (!this->include_section_group(layout
, i
, shdr
, &omit
))
601 else if ((shdr
.get_sh_flags() & elfcpp::SHF_GROUP
) == 0
602 && Layout::is_linkonce(name
))
604 if (!this->include_linkonce_section(layout
, name
, shdr
))
611 // Do not include this section in the link.
612 map_sections
[i
].output_section
= NULL
;
616 // The .eh_frame section is special. It holds exception frame
617 // information that we need to read in order to generate the
618 // exception frame header. We process these after all the other
619 // sections so that the exception frame reader can reliably
620 // determine which sections are being discarded, and discard the
621 // corresponding information.
622 if (!parameters
->output_is_object()
623 && strcmp(name
, ".eh_frame") == 0
624 && this->check_eh_frame_flags(&shdr
))
626 eh_frame_sections
.push_back(i
);
631 Output_section
* os
= layout
->layout(this, i
, name
, shdr
,
632 reloc_shndx
[i
], reloc_type
[i
],
635 map_sections
[i
].output_section
= os
;
636 map_sections
[i
].offset
= offset
;
638 // If this section requires special handling, and if there are
639 // relocs that apply to it, then we must do the special handling
640 // before we apply the relocs.
641 if (offset
== -1 && reloc_shndx
[i
] != 0)
642 this->set_relocs_must_follow_section_writes();
645 layout
->layout_gnu_stack(seen_gnu_stack
, gnu_stack_flags
);
647 // Handle the .eh_frame sections at the end.
648 for (std::vector
<unsigned int>::const_iterator p
= eh_frame_sections
.begin();
649 p
!= eh_frame_sections
.end();
652 gold_assert(this->has_eh_frame_
);
653 gold_assert(sd
->external_symbols_offset
!= 0);
656 const unsigned char *pshdr
;
657 pshdr
= sd
->section_headers
->data() + i
* This::shdr_size
;
658 typename
This::Shdr
shdr(pshdr
);
661 Output_section
* os
= layout
->layout_eh_frame(this,
664 sd
->symbol_names
->data(),
665 sd
->symbol_names_size
,
670 map_sections
[i
].output_section
= os
;
671 map_sections
[i
].offset
= offset
;
673 // If this section requires special handling, and if there are
674 // relocs that apply to it, then we must do the special handling
675 // before we apply the relocs.
676 if (offset
== -1 && reloc_shndx
[i
] != 0)
677 this->set_relocs_must_follow_section_writes();
680 delete sd
->section_headers
;
681 sd
->section_headers
= NULL
;
682 delete sd
->section_names
;
683 sd
->section_names
= NULL
;
686 // Add the symbols to the symbol table.
688 template<int size
, bool big_endian
>
690 Sized_relobj
<size
, big_endian
>::do_add_symbols(Symbol_table
* symtab
,
691 Read_symbols_data
* sd
)
693 if (sd
->symbols
== NULL
)
695 gold_assert(sd
->symbol_names
== NULL
);
699 const int sym_size
= This::sym_size
;
700 size_t symcount
= ((sd
->symbols_size
- sd
->external_symbols_offset
)
702 if (static_cast<off_t
>(symcount
* sym_size
)
703 != sd
->symbols_size
- sd
->external_symbols_offset
)
705 this->error(_("size of symbols is not multiple of symbol size"));
709 this->symbols_
.resize(symcount
);
711 const char* sym_names
=
712 reinterpret_cast<const char*>(sd
->symbol_names
->data());
713 symtab
->add_from_relobj(this,
714 sd
->symbols
->data() + sd
->external_symbols_offset
,
715 symcount
, sym_names
, sd
->symbol_names_size
,
720 delete sd
->symbol_names
;
721 sd
->symbol_names
= NULL
;
724 // Finalize the local symbols. Here we record the file offset at
725 // which they should be output, we add their names to *POOL, and we
726 // add their values to THIS->LOCAL_VALUES_. Return the symbol index.
727 // This function is always called from the main thread. The actual
728 // output of the local symbols will occur in a separate task.
730 template<int size
, bool big_endian
>
732 Sized_relobj
<size
, big_endian
>::do_finalize_local_symbols(unsigned int index
,
736 gold_assert(this->symtab_shndx_
!= -1U);
737 if (this->symtab_shndx_
== 0)
739 // This object has no symbols. Weird but legal.
743 gold_assert(off
== static_cast<off_t
>(align_address(off
, size
>> 3)));
745 this->local_symbol_offset_
= off
;
747 // Read the symbol table section header.
748 const unsigned int symtab_shndx
= this->symtab_shndx_
;
749 typename
This::Shdr
symtabshdr(this,
750 this->elf_file_
.section_header(symtab_shndx
));
751 gold_assert(symtabshdr
.get_sh_type() == elfcpp::SHT_SYMTAB
);
753 // Read the local symbols.
754 const int sym_size
= This::sym_size
;
755 const unsigned int loccount
= this->local_symbol_count_
;
756 gold_assert(loccount
== symtabshdr
.get_sh_info());
757 off_t locsize
= loccount
* sym_size
;
758 const unsigned char* psyms
= this->get_view(symtabshdr
.get_sh_offset(),
761 this->local_values_
.resize(loccount
);
763 // Read the symbol names.
764 const unsigned int strtab_shndx
= symtabshdr
.get_sh_link();
766 const unsigned char* pnamesu
= this->section_contents(strtab_shndx
,
769 const char* pnames
= reinterpret_cast<const char*>(pnamesu
);
771 // Loop over the local symbols.
773 const std::vector
<Map_to_output
>& mo(this->map_to_output());
774 unsigned int shnum
= this->shnum();
775 unsigned int count
= 0;
776 // Skip the first, dummy, symbol.
778 for (unsigned int i
= 1; i
< loccount
; ++i
, psyms
+= sym_size
)
780 elfcpp::Sym
<size
, big_endian
> sym(psyms
);
782 Symbol_value
<size
>& lv(this->local_values_
[i
]);
784 unsigned int shndx
= sym
.get_st_shndx();
785 lv
.set_input_shndx(shndx
);
787 if (sym
.get_st_type() == elfcpp::STT_SECTION
)
788 lv
.set_is_section_symbol();
790 if (shndx
>= elfcpp::SHN_LORESERVE
)
792 if (shndx
== elfcpp::SHN_ABS
)
793 lv
.set_output_value(sym
.get_st_value());
796 // FIXME: Handle SHN_XINDEX.
797 this->error(_("unknown section index %u for local symbol %u"),
799 lv
.set_output_value(0);
806 this->error(_("local symbol %u section index %u out of range"),
811 Output_section
* os
= mo
[shndx
].output_section
;
815 lv
.set_output_value(0);
816 lv
.set_no_output_symtab_entry();
820 if (mo
[shndx
].offset
== -1)
821 lv
.set_input_value(sym
.get_st_value());
823 lv
.set_output_value(mo
[shndx
].output_section
->address()
825 + sym
.get_st_value());
828 // Decide whether this symbol should go into the output file.
830 if (sym
.get_st_type() == elfcpp::STT_SECTION
)
832 lv
.set_no_output_symtab_entry();
836 if (sym
.get_st_name() >= strtab_size
)
838 this->error(_("local symbol %u section name out of range: %u >= %u"),
839 i
, sym
.get_st_name(),
840 static_cast<unsigned int>(strtab_size
));
841 lv
.set_no_output_symtab_entry();
845 const char* name
= pnames
+ sym
.get_st_name();
846 pool
->add(name
, true, NULL
);
847 lv
.set_output_symtab_index(index
);
852 this->output_local_symbol_count_
= count
;
857 // Return the value of the local symbol symndx.
858 template<int size
, bool big_endian
>
859 typename
elfcpp::Elf_types
<size
>::Elf_Addr
860 Sized_relobj
<size
, big_endian
>::local_symbol_value(unsigned int symndx
) const
862 gold_assert(symndx
< this->local_symbol_count_
);
863 gold_assert(symndx
< this->local_values_
.size());
864 const Symbol_value
<size
>& lv(this->local_values_
[symndx
]);
865 return lv
.value(this, 0);
868 // Return the value of a local symbol defined in input section SHNDX,
869 // with value VALUE, adding addend ADDEND. IS_SECTION_SYMBOL
870 // indicates whether the symbol is a section symbol. This handles
871 // SHF_MERGE sections.
872 template<int size
, bool big_endian
>
873 typename
elfcpp::Elf_types
<size
>::Elf_Addr
874 Sized_relobj
<size
, big_endian
>::local_value(unsigned int shndx
,
876 bool is_section_symbol
,
877 Address addend
) const
879 const std::vector
<Map_to_output
>& mo(this->map_to_output());
880 Output_section
* os
= mo
[shndx
].output_section
;
883 gold_assert(mo
[shndx
].offset
== -1);
885 // Do the mapping required by the output section. If this is not a
886 // section symbol, then we want to map the symbol value, and then
887 // include the addend. If this is a section symbol, then we need to
888 // include the addend to figure out where in the section we are,
889 // before we do the mapping. This will do the right thing provided
890 // the assembler is careful to only convert a relocation in a merged
891 // section to a section symbol if there is a zero addend. If the
892 // assembler does not do this, then in general we can't know what to
893 // do, because we can't distinguish the addend for the instruction
894 // format from the addend for the section offset.
896 if (is_section_symbol
)
897 return os
->output_address(this, shndx
, value
+ addend
);
899 return addend
+ os
->output_address(this, shndx
, value
);
902 // Write out the local symbols.
904 template<int size
, bool big_endian
>
906 Sized_relobj
<size
, big_endian
>::write_local_symbols(Output_file
* of
,
907 const Stringpool
* sympool
)
909 if (parameters
->strip_all())
912 gold_assert(this->symtab_shndx_
!= -1U);
913 if (this->symtab_shndx_
== 0)
915 // This object has no symbols. Weird but legal.
919 // Read the symbol table section header.
920 const unsigned int symtab_shndx
= this->symtab_shndx_
;
921 typename
This::Shdr
symtabshdr(this,
922 this->elf_file_
.section_header(symtab_shndx
));
923 gold_assert(symtabshdr
.get_sh_type() == elfcpp::SHT_SYMTAB
);
924 const unsigned int loccount
= this->local_symbol_count_
;
925 gold_assert(loccount
== symtabshdr
.get_sh_info());
927 // Read the local symbols.
928 const int sym_size
= This::sym_size
;
929 off_t locsize
= loccount
* sym_size
;
930 const unsigned char* psyms
= this->get_view(symtabshdr
.get_sh_offset(),
933 // Read the symbol names.
934 const unsigned int strtab_shndx
= symtabshdr
.get_sh_link();
936 const unsigned char* pnamesu
= this->section_contents(strtab_shndx
,
939 const char* pnames
= reinterpret_cast<const char*>(pnamesu
);
941 // Get a view into the output file.
942 off_t output_size
= this->output_local_symbol_count_
* sym_size
;
943 unsigned char* oview
= of
->get_output_view(this->local_symbol_offset_
,
946 const std::vector
<Map_to_output
>& mo(this->map_to_output());
948 gold_assert(this->local_values_
.size() == loccount
);
950 unsigned char* ov
= oview
;
952 for (unsigned int i
= 1; i
< loccount
; ++i
, psyms
+= sym_size
)
954 elfcpp::Sym
<size
, big_endian
> isym(psyms
);
956 if (!this->local_values_
[i
].needs_output_symtab_entry())
959 unsigned int st_shndx
= isym
.get_st_shndx();
960 if (st_shndx
< elfcpp::SHN_LORESERVE
)
962 gold_assert(st_shndx
< mo
.size());
963 if (mo
[st_shndx
].output_section
== NULL
)
965 st_shndx
= mo
[st_shndx
].output_section
->out_shndx();
968 elfcpp::Sym_write
<size
, big_endian
> osym(ov
);
970 gold_assert(isym
.get_st_name() < strtab_size
);
971 const char* name
= pnames
+ isym
.get_st_name();
972 osym
.put_st_name(sympool
->get_offset(name
));
973 osym
.put_st_value(this->local_values_
[i
].value(this, 0));
974 osym
.put_st_size(isym
.get_st_size());
975 osym
.put_st_info(isym
.get_st_info());
976 osym
.put_st_other(isym
.get_st_other());
977 osym
.put_st_shndx(st_shndx
);
982 gold_assert(ov
- oview
== output_size
);
984 of
->write_output_view(this->local_symbol_offset_
, output_size
, oview
);
987 // Set *INFO to symbolic information about the offset OFFSET in the
988 // section SHNDX. Return true if we found something, false if we
991 template<int size
, bool big_endian
>
993 Sized_relobj
<size
, big_endian
>::get_symbol_location_info(
996 Symbol_location_info
* info
)
998 if (this->symtab_shndx_
== 0)
1002 const unsigned char* symbols
= this->section_contents(this->symtab_shndx_
,
1006 unsigned int symbol_names_shndx
= this->section_link(this->symtab_shndx_
);
1008 const unsigned char* symbol_names_u
=
1009 this->section_contents(symbol_names_shndx
, &names_size
, false);
1010 const char* symbol_names
= reinterpret_cast<const char*>(symbol_names_u
);
1012 const int sym_size
= This::sym_size
;
1013 const size_t count
= symbols_size
/ sym_size
;
1015 const unsigned char* p
= symbols
;
1016 for (size_t i
= 0; i
< count
; ++i
, p
+= sym_size
)
1018 elfcpp::Sym
<size
, big_endian
> sym(p
);
1020 if (sym
.get_st_type() == elfcpp::STT_FILE
)
1022 if (sym
.get_st_name() >= names_size
)
1023 info
->source_file
= "(invalid)";
1025 info
->source_file
= symbol_names
+ sym
.get_st_name();
1027 else if (sym
.get_st_shndx() == shndx
1028 && static_cast<off_t
>(sym
.get_st_value()) <= offset
1029 && (static_cast<off_t
>(sym
.get_st_value() + sym
.get_st_size())
1032 if (sym
.get_st_name() > names_size
)
1033 info
->enclosing_symbol_name
= "(invalid)";
1035 info
->enclosing_symbol_name
= symbol_names
+ sym
.get_st_name();
1043 // Input_objects methods.
1045 // Add a regular relocatable object to the list. Return false if this
1046 // object should be ignored.
1049 Input_objects::add_object(Object
* obj
)
1051 Target
* target
= obj
->target();
1052 if (this->target_
== NULL
)
1053 this->target_
= target
;
1054 else if (this->target_
!= target
)
1056 gold_error(_("%s: incompatible target"), obj
->name().c_str());
1060 if (!obj
->is_dynamic())
1061 this->relobj_list_
.push_back(static_cast<Relobj
*>(obj
));
1064 // See if this is a duplicate SONAME.
1065 Dynobj
* dynobj
= static_cast<Dynobj
*>(obj
);
1066 const char* soname
= dynobj
->soname();
1068 std::pair
<Unordered_set
<std::string
>::iterator
, bool> ins
=
1069 this->sonames_
.insert(soname
);
1072 // We have already seen a dynamic object with this soname.
1076 this->dynobj_list_
.push_back(dynobj
);
1078 // If this is -lc, remember the directory in which we found it.
1079 // We use this when issuing warnings about undefined symbols: as
1080 // a heuristic, we don't warn about system libraries found in
1081 // the same directory as -lc.
1082 if (strncmp(soname
, "libc.so", 7) == 0)
1084 const char* object_name
= dynobj
->name().c_str();
1085 const char* base
= lbasename(object_name
);
1086 if (base
!= object_name
)
1087 this->system_library_directory_
.assign(object_name
,
1088 base
- 1 - object_name
);
1092 set_parameters_size_and_endianness(target
->get_size(),
1093 target
->is_big_endian());
1098 // Return whether an object was found in the system library directory.
1101 Input_objects::found_in_system_library_directory(const Object
* object
) const
1103 return (!this->system_library_directory_
.empty()
1104 && object
->name().compare(0,
1105 this->system_library_directory_
.size(),
1106 this->system_library_directory_
) == 0);
1109 // For each dynamic object, record whether we've seen all of its
1110 // explicit dependencies.
1113 Input_objects::check_dynamic_dependencies() const
1115 for (Dynobj_list::const_iterator p
= this->dynobj_list_
.begin();
1116 p
!= this->dynobj_list_
.end();
1119 const Dynobj::Needed
& needed((*p
)->needed());
1120 bool found_all
= true;
1121 for (Dynobj::Needed::const_iterator pneeded
= needed
.begin();
1122 pneeded
!= needed
.end();
1125 if (this->sonames_
.find(*pneeded
) == this->sonames_
.end())
1131 (*p
)->set_has_unknown_needed_entries(!found_all
);
1135 // Relocate_info methods.
1137 // Return a string describing the location of a relocation. This is
1138 // only used in error messages.
1140 template<int size
, bool big_endian
>
1142 Relocate_info
<size
, big_endian
>::location(size_t, off_t offset
) const
1144 // See if we can get line-number information from debugging sections.
1145 std::string filename
;
1146 std::string file_and_lineno
; // Better than filename-only, if available.
1148 Sized_dwarf_line_info
<size
, big_endian
> line_info(this->object
);
1149 // This will be "" if we failed to parse the debug info for any reason.
1150 file_and_lineno
= line_info
.addr2line(this->data_shndx
, offset
);
1152 std::string
ret(this->object
->name());
1154 Symbol_location_info info
;
1155 if (this->object
->get_symbol_location_info(this->data_shndx
, offset
, &info
))
1157 ret
+= " in function ";
1158 // We could demangle this name before printing, but we don't
1159 // bother because gcc runs linker output through a demangle
1160 // filter itself. The only advantage to demangling here is if
1161 // someone might call ld directly, rather than via gcc. If we
1162 // did want to demangle, cplus_demangle() is in libiberty.
1163 ret
+= info
.enclosing_symbol_name
;
1165 filename
= info
.source_file
;
1168 if (!file_and_lineno
.empty())
1169 ret
+= file_and_lineno
;
1172 if (!filename
.empty())
1175 ret
+= this->object
->section_name(this->data_shndx
);
1177 // Offsets into sections have to be positive.
1178 snprintf(buf
, sizeof(buf
), "+0x%lx", static_cast<long>(offset
));
1185 } // End namespace gold.
1190 using namespace gold
;
1192 // Read an ELF file with the header and return the appropriate
1193 // instance of Object.
1195 template<int size
, bool big_endian
>
1197 make_elf_sized_object(const std::string
& name
, Input_file
* input_file
,
1198 off_t offset
, const elfcpp::Ehdr
<size
, big_endian
>& ehdr
)
1200 int et
= ehdr
.get_e_type();
1201 if (et
== elfcpp::ET_REL
)
1203 Sized_relobj
<size
, big_endian
>* obj
=
1204 new Sized_relobj
<size
, big_endian
>(name
, input_file
, offset
, ehdr
);
1208 else if (et
== elfcpp::ET_DYN
)
1210 Sized_dynobj
<size
, big_endian
>* obj
=
1211 new Sized_dynobj
<size
, big_endian
>(name
, input_file
, offset
, ehdr
);
1217 gold_error(_("%s: unsupported ELF file type %d"),
1223 } // End anonymous namespace.
1228 // Read an ELF file and return the appropriate instance of Object.
1231 make_elf_object(const std::string
& name
, Input_file
* input_file
, off_t offset
,
1232 const unsigned char* p
, off_t bytes
)
1234 if (bytes
< elfcpp::EI_NIDENT
)
1236 gold_error(_("%s: ELF file too short"), name
.c_str());
1240 int v
= p
[elfcpp::EI_VERSION
];
1241 if (v
!= elfcpp::EV_CURRENT
)
1243 if (v
== elfcpp::EV_NONE
)
1244 gold_error(_("%s: invalid ELF version 0"), name
.c_str());
1246 gold_error(_("%s: unsupported ELF version %d"), name
.c_str(), v
);
1250 int c
= p
[elfcpp::EI_CLASS
];
1251 if (c
== elfcpp::ELFCLASSNONE
)
1253 gold_error(_("%s: invalid ELF class 0"), name
.c_str());
1256 else if (c
!= elfcpp::ELFCLASS32
1257 && c
!= elfcpp::ELFCLASS64
)
1259 gold_error(_("%s: unsupported ELF class %d"), name
.c_str(), c
);
1263 int d
= p
[elfcpp::EI_DATA
];
1264 if (d
== elfcpp::ELFDATANONE
)
1266 gold_error(_("%s: invalid ELF data encoding"), name
.c_str());
1269 else if (d
!= elfcpp::ELFDATA2LSB
1270 && d
!= elfcpp::ELFDATA2MSB
)
1272 gold_error(_("%s: unsupported ELF data encoding %d"), name
.c_str(), d
);
1276 bool big_endian
= d
== elfcpp::ELFDATA2MSB
;
1278 if (c
== elfcpp::ELFCLASS32
)
1280 if (bytes
< elfcpp::Elf_sizes
<32>::ehdr_size
)
1282 gold_error(_("%s: ELF file too short"), name
.c_str());
1287 #ifdef HAVE_TARGET_32_BIG
1288 elfcpp::Ehdr
<32, true> ehdr(p
);
1289 return make_elf_sized_object
<32, true>(name
, input_file
,
1292 gold_error(_("%s: not configured to support "
1293 "32-bit big-endian object"),
1300 #ifdef HAVE_TARGET_32_LITTLE
1301 elfcpp::Ehdr
<32, false> ehdr(p
);
1302 return make_elf_sized_object
<32, false>(name
, input_file
,
1305 gold_error(_("%s: not configured to support "
1306 "32-bit little-endian object"),
1314 if (bytes
< elfcpp::Elf_sizes
<32>::ehdr_size
)
1316 gold_error(_("%s: ELF file too short"), name
.c_str());
1321 #ifdef HAVE_TARGET_64_BIG
1322 elfcpp::Ehdr
<64, true> ehdr(p
);
1323 return make_elf_sized_object
<64, true>(name
, input_file
,
1326 gold_error(_("%s: not configured to support "
1327 "64-bit big-endian object"),
1334 #ifdef HAVE_TARGET_64_LITTLE
1335 elfcpp::Ehdr
<64, false> ehdr(p
);
1336 return make_elf_sized_object
<64, false>(name
, input_file
,
1339 gold_error(_("%s: not configured to support "
1340 "64-bit little-endian object"),
1348 // Instantiate the templates we need. We could use the configure
1349 // script to restrict this to only the ones for implemented targets.
1351 #ifdef HAVE_TARGET_32_LITTLE
1353 class Sized_relobj
<32, false>;
1356 #ifdef HAVE_TARGET_32_BIG
1358 class Sized_relobj
<32, true>;
1361 #ifdef HAVE_TARGET_64_LITTLE
1363 class Sized_relobj
<64, false>;
1366 #ifdef HAVE_TARGET_64_BIG
1368 class Sized_relobj
<64, true>;
1371 #ifdef HAVE_TARGET_32_LITTLE
1373 struct Relocate_info
<32, false>;
1376 #ifdef HAVE_TARGET_32_BIG
1378 struct Relocate_info
<32, true>;
1381 #ifdef HAVE_TARGET_64_LITTLE
1383 struct Relocate_info
<64, false>;
1386 #ifdef HAVE_TARGET_64_BIG
1388 struct Relocate_info
<64, true>;
1391 } // End namespace gold.