1 // dynobj.cc -- dynamic object support for 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 "parameters.h"
38 // Sets up the default soname_ to use, in the (rare) cases we never
39 // see a DT_SONAME entry.
41 Dynobj::Dynobj(const std::string& name, Input_file* input_file, off_t offset)
42 : Object(name, input_file, true, offset),
44 unknown_needed_(UNKNOWN_NEEDED_UNSET)
46 // This will be overridden by a DT_SONAME entry, hopefully. But if
47 // we never see a DT_SONAME entry, our rule is to use the dynamic
48 // object's filename. The only exception is when the dynamic object
49 // is part of an archive (so the filename is the archive's
50 // filename). In that case, we use just the dynobj's name-in-archive.
51 this->soname_ = this->input_file()->found_name();
52 if (this->offset() != 0)
54 std::string::size_type open_paren = this->name().find('(');
55 std::string::size_type close_paren = this->name().find(')');
56 if (open_paren != std::string::npos && close_paren != std::string::npos)
58 // It's an archive, and name() is of the form 'foo.a(bar.so)'.
59 this->soname_ = this->name().substr(open_paren + 1,
60 close_paren - (open_paren + 1));
65 // Class Sized_dynobj.
67 template<int size, bool big_endian>
68 Sized_dynobj<size, big_endian>::Sized_dynobj(
69 const std::string& name,
70 Input_file* input_file,
72 const elfcpp::Ehdr<size, big_endian>& ehdr)
73 : Dynobj(name, input_file, offset),
80 template<int size, bool big_endian>
82 Sized_dynobj<size, big_endian>::setup(
83 const elfcpp::Ehdr<size, big_endian>& ehdr)
85 this->set_target(ehdr.get_e_machine(), size, big_endian,
86 ehdr.get_e_ident()[elfcpp::EI_OSABI],
87 ehdr.get_e_ident()[elfcpp::EI_ABIVERSION]);
89 const unsigned int shnum = this->elf_file_.shnum();
90 this->set_shnum(shnum);
93 // Find the SHT_DYNSYM section and the various version sections, and
94 // the dynamic section, given the section headers.
96 template<int size, bool big_endian>
98 Sized_dynobj<size, big_endian>::find_dynsym_sections(
99 const unsigned char* pshdrs,
100 unsigned int* pdynsym_shndx,
101 unsigned int* pversym_shndx,
102 unsigned int* pverdef_shndx,
103 unsigned int* pverneed_shndx,
104 unsigned int* pdynamic_shndx)
106 *pdynsym_shndx = -1U;
107 *pversym_shndx = -1U;
108 *pverdef_shndx = -1U;
109 *pverneed_shndx = -1U;
110 *pdynamic_shndx = -1U;
112 const unsigned int shnum = this->shnum();
113 const unsigned char* p = pshdrs;
114 for (unsigned int i = 0; i < shnum; ++i, p += This::shdr_size)
116 typename This::Shdr shdr(p);
119 switch (shdr.get_sh_type())
121 case elfcpp::SHT_DYNSYM:
124 case elfcpp::SHT_GNU_versym:
127 case elfcpp::SHT_GNU_verdef:
130 case elfcpp::SHT_GNU_verneed:
133 case elfcpp::SHT_DYNAMIC:
145 this->error(_("unexpected duplicate type %u section: %u, %u"),
146 shdr.get_sh_type(), *pi, i);
152 // Read the contents of section SHNDX. PSHDRS points to the section
153 // headers. TYPE is the expected section type. LINK is the expected
154 // section link. Store the data in *VIEW and *VIEW_SIZE. The
155 // section's sh_info field is stored in *VIEW_INFO.
157 template<int size, bool big_endian>
159 Sized_dynobj<size, big_endian>::read_dynsym_section(
160 const unsigned char* pshdrs,
166 unsigned int* view_info)
176 typename This::Shdr shdr(pshdrs + shndx * This::shdr_size);
178 gold_assert(shdr.get_sh_type() == type);
180 if (shdr.get_sh_link() != link)
181 this->error(_("unexpected link in section %u header: %u != %u"),
182 shndx, shdr.get_sh_link(), link);
184 *view = this->get_lasting_view(shdr.get_sh_offset(), shdr.get_sh_size(),
186 *view_size = shdr.get_sh_size();
187 *view_info = shdr.get_sh_info();
190 // Read the dynamic tags. Set the soname field if this shared object
191 // has a DT_SONAME tag. Record the DT_NEEDED tags. PSHDRS points to
192 // the section headers. DYNAMIC_SHNDX is the section index of the
193 // SHT_DYNAMIC section. STRTAB_SHNDX, STRTAB, and STRTAB_SIZE are the
194 // section index and contents of a string table which may be the one
195 // associated with the SHT_DYNAMIC section.
197 template<int size, bool big_endian>
199 Sized_dynobj<size, big_endian>::read_dynamic(const unsigned char* pshdrs,
200 unsigned int dynamic_shndx,
201 unsigned int strtab_shndx,
202 const unsigned char* strtabu,
205 typename This::Shdr dynamicshdr(pshdrs + dynamic_shndx * This::shdr_size);
206 gold_assert(dynamicshdr.get_sh_type() == elfcpp::SHT_DYNAMIC);
208 const off_t dynamic_size = dynamicshdr.get_sh_size();
209 const unsigned char* pdynamic = this->get_view(dynamicshdr.get_sh_offset(),
210 dynamic_size, false);
212 const unsigned int link = dynamicshdr.get_sh_link();
213 if (link != strtab_shndx)
215 if (link >= this->shnum())
217 this->error(_("DYNAMIC section %u link out of range: %u"),
218 dynamic_shndx, link);
222 typename This::Shdr strtabshdr(pshdrs + link * This::shdr_size);
223 if (strtabshdr.get_sh_type() != elfcpp::SHT_STRTAB)
225 this->error(_("DYNAMIC section %u link %u is not a strtab"),
226 dynamic_shndx, link);
230 strtab_size = strtabshdr.get_sh_size();
231 strtabu = this->get_view(strtabshdr.get_sh_offset(), strtab_size, false);
234 const char* const strtab = reinterpret_cast<const char*>(strtabu);
236 for (const unsigned char* p = pdynamic;
237 p < pdynamic + dynamic_size;
240 typename This::Dyn dyn(p);
242 switch (dyn.get_d_tag())
244 case elfcpp::DT_NULL:
245 // We should always see DT_NULL at the end of the dynamic
249 case elfcpp::DT_SONAME:
251 off_t val = dyn.get_d_val();
252 if (val >= strtab_size)
253 this->error(_("DT_SONAME value out of range: %lld >= %lld"),
254 static_cast<long long>(val),
255 static_cast<long long>(strtab_size));
257 this->set_soname_string(strtab + val);
261 case elfcpp::DT_NEEDED:
263 off_t val = dyn.get_d_val();
264 if (val >= strtab_size)
265 this->error(_("DT_NEEDED value out of range: %lld >= %lld"),
266 static_cast<long long>(val),
267 static_cast<long long>(strtab_size));
269 this->add_needed(strtab + val);
278 this->error(_("missing DT_NULL in dynamic segment"));
281 // Read the symbols and sections from a dynamic object. We read the
282 // dynamic symbols, not the normal symbols.
284 template<int size, bool big_endian>
286 Sized_dynobj<size, big_endian>::do_read_symbols(Read_symbols_data* sd)
288 this->read_section_data(&this->elf_file_, sd);
290 const unsigned char* const pshdrs = sd->section_headers->data();
292 unsigned int dynsym_shndx;
293 unsigned int versym_shndx;
294 unsigned int verdef_shndx;
295 unsigned int verneed_shndx;
296 unsigned int dynamic_shndx;
297 this->find_dynsym_sections(pshdrs, &dynsym_shndx, &versym_shndx,
298 &verdef_shndx, &verneed_shndx, &dynamic_shndx);
300 unsigned int strtab_shndx = -1U;
303 sd->symbols_size = 0;
304 sd->external_symbols_offset = 0;
305 sd->symbol_names = NULL;
306 sd->symbol_names_size = 0;
308 if (dynsym_shndx != -1U)
310 // Get the dynamic symbols.
311 typename This::Shdr dynsymshdr(pshdrs + dynsym_shndx * This::shdr_size);
312 gold_assert(dynsymshdr.get_sh_type() == elfcpp::SHT_DYNSYM);
314 sd->symbols = this->get_lasting_view(dynsymshdr.get_sh_offset(),
315 dynsymshdr.get_sh_size(), false);
316 sd->symbols_size = dynsymshdr.get_sh_size();
318 // Get the symbol names.
319 strtab_shndx = dynsymshdr.get_sh_link();
320 if (strtab_shndx >= this->shnum())
322 this->error(_("invalid dynamic symbol table name index: %u"),
326 typename This::Shdr strtabshdr(pshdrs + strtab_shndx * This::shdr_size);
327 if (strtabshdr.get_sh_type() != elfcpp::SHT_STRTAB)
329 this->error(_("dynamic symbol table name section "
330 "has wrong type: %u"),
331 static_cast<unsigned int>(strtabshdr.get_sh_type()));
335 sd->symbol_names = this->get_lasting_view(strtabshdr.get_sh_offset(),
336 strtabshdr.get_sh_size(),
338 sd->symbol_names_size = strtabshdr.get_sh_size();
340 // Get the version information.
343 this->read_dynsym_section(pshdrs, versym_shndx, elfcpp::SHT_GNU_versym,
344 dynsym_shndx, &sd->versym, &sd->versym_size,
347 // We require that the version definition and need section link
348 // to the same string table as the dynamic symbol table. This
349 // is not a technical requirement, but it always happens in
350 // practice. We could change this if necessary.
352 this->read_dynsym_section(pshdrs, verdef_shndx, elfcpp::SHT_GNU_verdef,
353 strtab_shndx, &sd->verdef, &sd->verdef_size,
356 this->read_dynsym_section(pshdrs, verneed_shndx, elfcpp::SHT_GNU_verneed,
357 strtab_shndx, &sd->verneed, &sd->verneed_size,
361 // Read the SHT_DYNAMIC section to find whether this shared object
362 // has a DT_SONAME tag and to record any DT_NEEDED tags. This
363 // doesn't really have anything to do with reading the symbols, but
364 // this is a convenient place to do it.
365 if (dynamic_shndx != -1U)
366 this->read_dynamic(pshdrs, dynamic_shndx, strtab_shndx,
367 (sd->symbol_names == NULL
369 : sd->symbol_names->data()),
370 sd->symbol_names_size);
373 // Lay out the input sections for a dynamic object. We don't want to
374 // include sections from a dynamic object, so all that we actually do
375 // here is check for .gnu.warning sections.
377 template<int size, bool big_endian>
379 Sized_dynobj<size, big_endian>::do_layout(Symbol_table* symtab,
381 Read_symbols_data* sd)
383 const unsigned int shnum = this->shnum();
387 // Get the section headers.
388 const unsigned char* pshdrs = sd->section_headers->data();
390 // Get the section names.
391 const unsigned char* pnamesu = sd->section_names->data();
392 const char* pnames = reinterpret_cast<const char*>(pnamesu);
394 // Skip the first, dummy, section.
395 pshdrs += This::shdr_size;
396 for (unsigned int i = 1; i < shnum; ++i, pshdrs += This::shdr_size)
398 typename This::Shdr shdr(pshdrs);
400 if (shdr.get_sh_name() >= sd->section_names_size)
402 this->error(_("bad section name offset for section %u: %lu"),
403 i, static_cast<unsigned long>(shdr.get_sh_name()));
407 const char* name = pnames + shdr.get_sh_name();
409 this->handle_gnu_warning_section(name, i, symtab);
412 delete sd->section_headers;
413 sd->section_headers = NULL;
414 delete sd->section_names;
415 sd->section_names = NULL;
418 // Add an entry to the vector mapping version numbers to version
421 template<int size, bool big_endian>
423 Sized_dynobj<size, big_endian>::set_version_map(
424 Version_map* version_map,
426 const char* name) const
428 if (ndx >= version_map->size())
429 version_map->resize(ndx + 1);
430 if ((*version_map)[ndx] != NULL)
431 this->error(_("duplicate definition for version %u"), ndx);
432 (*version_map)[ndx] = name;
435 // Add mappings for the version definitions to VERSION_MAP.
437 template<int size, bool big_endian>
439 Sized_dynobj<size, big_endian>::make_verdef_map(
440 Read_symbols_data* sd,
441 Version_map* version_map) const
443 if (sd->verdef == NULL)
446 const char* names = reinterpret_cast<const char*>(sd->symbol_names->data());
447 off_t names_size = sd->symbol_names_size;
449 const unsigned char* pverdef = sd->verdef->data();
450 off_t verdef_size = sd->verdef_size;
451 const unsigned int count = sd->verdef_info;
453 const unsigned char* p = pverdef;
454 for (unsigned int i = 0; i < count; ++i)
456 elfcpp::Verdef<size, big_endian> verdef(p);
458 if (verdef.get_vd_version() != elfcpp::VER_DEF_CURRENT)
460 this->error(_("unexpected verdef version %u"),
461 verdef.get_vd_version());
465 const unsigned int vd_ndx = verdef.get_vd_ndx();
467 // The GNU linker clears the VERSYM_HIDDEN bit. I'm not
470 // The first Verdaux holds the name of this version. Subsequent
471 // ones are versions that this one depends upon, which we don't
473 const unsigned int vd_cnt = verdef.get_vd_cnt();
476 this->error(_("verdef vd_cnt field too small: %u"), vd_cnt);
480 const unsigned int vd_aux = verdef.get_vd_aux();
481 if ((p - pverdef) + vd_aux >= verdef_size)
483 this->error(_("verdef vd_aux field out of range: %u"), vd_aux);
487 const unsigned char* pvda = p + vd_aux;
488 elfcpp::Verdaux<size, big_endian> verdaux(pvda);
490 const unsigned int vda_name = verdaux.get_vda_name();
491 if (vda_name >= names_size)
493 this->error(_("verdaux vda_name field out of range: %u"), vda_name);
497 this->set_version_map(version_map, vd_ndx, names + vda_name);
499 const unsigned int vd_next = verdef.get_vd_next();
500 if ((p - pverdef) + vd_next >= verdef_size)
502 this->error(_("verdef vd_next field out of range: %u"), vd_next);
510 // Add mappings for the required versions to VERSION_MAP.
512 template<int size, bool big_endian>
514 Sized_dynobj<size, big_endian>::make_verneed_map(
515 Read_symbols_data* sd,
516 Version_map* version_map) const
518 if (sd->verneed == NULL)
521 const char* names = reinterpret_cast<const char*>(sd->symbol_names->data());
522 off_t names_size = sd->symbol_names_size;
524 const unsigned char* pverneed = sd->verneed->data();
525 const off_t verneed_size = sd->verneed_size;
526 const unsigned int count = sd->verneed_info;
528 const unsigned char* p = pverneed;
529 for (unsigned int i = 0; i < count; ++i)
531 elfcpp::Verneed<size, big_endian> verneed(p);
533 if (verneed.get_vn_version() != elfcpp::VER_NEED_CURRENT)
535 this->error(_("unexpected verneed version %u"),
536 verneed.get_vn_version());
540 const unsigned int vn_aux = verneed.get_vn_aux();
542 if ((p - pverneed) + vn_aux >= verneed_size)
544 this->error(_("verneed vn_aux field out of range: %u"), vn_aux);
548 const unsigned int vn_cnt = verneed.get_vn_cnt();
549 const unsigned char* pvna = p + vn_aux;
550 for (unsigned int j = 0; j < vn_cnt; ++j)
552 elfcpp::Vernaux<size, big_endian> vernaux(pvna);
554 const unsigned int vna_name = vernaux.get_vna_name();
555 if (vna_name >= names_size)
557 this->error(_("vernaux vna_name field out of range: %u"),
562 this->set_version_map(version_map, vernaux.get_vna_other(),
565 const unsigned int vna_next = vernaux.get_vna_next();
566 if ((pvna - pverneed) + vna_next >= verneed_size)
568 this->error(_("verneed vna_next field out of range: %u"),
576 const unsigned int vn_next = verneed.get_vn_next();
577 if ((p - pverneed) + vn_next >= verneed_size)
579 this->error(_("verneed vn_next field out of range: %u"), vn_next);
587 // Create a vector mapping version numbers to version strings.
589 template<int size, bool big_endian>
591 Sized_dynobj<size, big_endian>::make_version_map(
592 Read_symbols_data* sd,
593 Version_map* version_map) const
595 if (sd->verdef == NULL && sd->verneed == NULL)
598 // A guess at the maximum version number we will see. If this is
599 // wrong we will be less efficient but still correct.
600 version_map->reserve(sd->verdef_info + sd->verneed_info * 10);
602 this->make_verdef_map(sd, version_map);
603 this->make_verneed_map(sd, version_map);
606 // Add the dynamic symbols to the symbol table.
608 template<int size, bool big_endian>
610 Sized_dynobj<size, big_endian>::do_add_symbols(Symbol_table* symtab,
611 Read_symbols_data* sd)
613 if (sd->symbols == NULL)
615 gold_assert(sd->symbol_names == NULL);
616 gold_assert(sd->versym == NULL && sd->verdef == NULL
617 && sd->verneed == NULL);
621 const int sym_size = This::sym_size;
622 const size_t symcount = sd->symbols_size / sym_size;
623 gold_assert(sd->external_symbols_offset == 0);
624 if (static_cast<off_t>(symcount * sym_size) != sd->symbols_size)
626 this->error(_("size of dynamic symbols is not multiple of symbol size"));
630 Version_map version_map;
631 this->make_version_map(sd, &version_map);
633 const char* sym_names =
634 reinterpret_cast<const char*>(sd->symbol_names->data());
635 symtab->add_from_dynobj(this, sd->symbols->data(), symcount,
636 sym_names, sd->symbol_names_size,
639 : sd->versym->data()),
645 delete sd->symbol_names;
646 sd->symbol_names = NULL;
647 if (sd->versym != NULL)
652 if (sd->verdef != NULL)
657 if (sd->verneed != NULL)
664 // Given a vector of hash codes, compute the number of hash buckets to
668 Dynobj::compute_bucket_count(const std::vector<uint32_t>& hashcodes,
669 bool for_gnu_hash_table)
671 // FIXME: Implement optional hash table optimization.
673 // Array used to determine the number of hash table buckets to use
674 // based on the number of symbols there are. If there are fewer
675 // than 3 symbols we use 1 bucket, fewer than 17 symbols we use 3
676 // buckets, fewer than 37 we use 17 buckets, and so forth. We never
677 // use more than 32771 buckets. This is straight from the old GNU
679 static const unsigned int buckets[] =
681 1, 3, 17, 37, 67, 97, 131, 197, 263, 521, 1031, 2053, 4099, 8209,
684 const int buckets_count = sizeof buckets / sizeof buckets[0];
686 unsigned int symcount = hashcodes.size();
687 unsigned int ret = 1;
688 for (int i = 0; i < buckets_count; ++i)
690 if (symcount < buckets[i])
695 if (for_gnu_hash_table && ret < 2)
701 // The standard ELF hash function. This hash function must not
702 // change, as the dynamic linker uses it also.
705 Dynobj::elf_hash(const char* name)
707 const unsigned char* nameu = reinterpret_cast<const unsigned char*>(name);
710 while ((c = *nameu++) != '\0')
713 uint32_t g = h & 0xf0000000;
717 // The ELF ABI says h &= ~g, but using xor is equivalent in
718 // this case (since g was set from h) and may save one
726 // Create a standard ELF hash table, setting *PPHASH and *PHASHLEN.
727 // DYNSYMS is a vector with all the global dynamic symbols.
728 // LOCAL_DYNSYM_COUNT is the number of local symbols in the dynamic
732 Dynobj::create_elf_hash_table(const std::vector<Symbol*>& dynsyms,
733 unsigned int local_dynsym_count,
734 unsigned char** pphash,
735 unsigned int* phashlen)
737 unsigned int dynsym_count = dynsyms.size();
739 // Get the hash values for all the symbols.
740 std::vector<uint32_t> dynsym_hashvals(dynsym_count);
741 for (unsigned int i = 0; i < dynsym_count; ++i)
742 dynsym_hashvals[i] = Dynobj::elf_hash(dynsyms[i]->name());
744 const unsigned int bucketcount =
745 Dynobj::compute_bucket_count(dynsym_hashvals, false);
747 std::vector<uint32_t> bucket(bucketcount);
748 std::vector<uint32_t> chain(local_dynsym_count + dynsym_count);
750 for (unsigned int i = 0; i < dynsym_count; ++i)
752 unsigned int dynsym_index = dynsyms[i]->dynsym_index();
753 unsigned int bucketpos = dynsym_hashvals[i] % bucketcount;
754 chain[dynsym_index] = bucket[bucketpos];
755 bucket[bucketpos] = dynsym_index;
758 unsigned int hashlen = ((2
763 unsigned char* phash = new unsigned char[hashlen];
765 if (parameters->is_big_endian())
767 #if defined(HAVE_TARGET_32_BIG) || defined(HAVE_TARGET_64_BIG)
768 Dynobj::sized_create_elf_hash_table<true>(bucket, chain, phash,
776 #if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_64_LITTLE)
777 Dynobj::sized_create_elf_hash_table<false>(bucket, chain, phash,
788 // Fill in an ELF hash table.
790 template<bool big_endian>
792 Dynobj::sized_create_elf_hash_table(const std::vector<uint32_t>& bucket,
793 const std::vector<uint32_t>& chain,
794 unsigned char* phash,
795 unsigned int hashlen)
797 unsigned char* p = phash;
799 const unsigned int bucketcount = bucket.size();
800 const unsigned int chaincount = chain.size();
802 elfcpp::Swap<32, big_endian>::writeval(p, bucketcount);
804 elfcpp::Swap<32, big_endian>::writeval(p, chaincount);
807 for (unsigned int i = 0; i < bucketcount; ++i)
809 elfcpp::Swap<32, big_endian>::writeval(p, bucket[i]);
813 for (unsigned int i = 0; i < chaincount; ++i)
815 elfcpp::Swap<32, big_endian>::writeval(p, chain[i]);
819 gold_assert(static_cast<unsigned int>(p - phash) == hashlen);
822 // The hash function used for the GNU hash table. This hash function
823 // must not change, as the dynamic linker uses it also.
826 Dynobj::gnu_hash(const char* name)
828 const unsigned char* nameu = reinterpret_cast<const unsigned char*>(name);
831 while ((c = *nameu++) != '\0')
832 h = (h << 5) + h + c;
836 // Create a GNU hash table, setting *PPHASH and *PHASHLEN. GNU hash
837 // tables are an extension to ELF which are recognized by the GNU
838 // dynamic linker. They are referenced using dynamic tag DT_GNU_HASH.
839 // TARGET is the target. DYNSYMS is a vector with all the global
840 // symbols which will be going into the dynamic symbol table.
841 // LOCAL_DYNSYM_COUNT is the number of local symbols in the dynamic
845 Dynobj::create_gnu_hash_table(const std::vector<Symbol*>& dynsyms,
846 unsigned int local_dynsym_count,
847 unsigned char** pphash,
848 unsigned int* phashlen)
850 const unsigned int count = dynsyms.size();
852 // Sort the dynamic symbols into two vectors. Symbols which we do
853 // not want to put into the hash table we store into
854 // UNHASHED_DYNSYMS. Symbols which we do want to store we put into
855 // HASHED_DYNSYMS. DYNSYM_HASHVALS is parallel to HASHED_DYNSYMS,
856 // and records the hash codes.
858 std::vector<Symbol*> unhashed_dynsyms;
859 unhashed_dynsyms.reserve(count);
861 std::vector<Symbol*> hashed_dynsyms;
862 hashed_dynsyms.reserve(count);
864 std::vector<uint32_t> dynsym_hashvals;
865 dynsym_hashvals.reserve(count);
867 for (unsigned int i = 0; i < count; ++i)
869 Symbol* sym = dynsyms[i];
871 // FIXME: Should put on unhashed_dynsyms if the symbol is
873 if (sym->is_undefined())
874 unhashed_dynsyms.push_back(sym);
877 hashed_dynsyms.push_back(sym);
878 dynsym_hashvals.push_back(Dynobj::gnu_hash(sym->name()));
882 // Put the unhashed symbols at the start of the global portion of
883 // the dynamic symbol table.
884 const unsigned int unhashed_count = unhashed_dynsyms.size();
885 unsigned int unhashed_dynsym_index = local_dynsym_count;
886 for (unsigned int i = 0; i < unhashed_count; ++i)
888 unhashed_dynsyms[i]->set_dynsym_index(unhashed_dynsym_index);
889 ++unhashed_dynsym_index;
892 // For the actual data generation we call out to a templatized
894 int size = parameters->get_size();
895 bool big_endian = parameters->is_big_endian();
900 #ifdef HAVE_TARGET_32_BIG
901 Dynobj::sized_create_gnu_hash_table<32, true>(hashed_dynsyms,
903 unhashed_dynsym_index,
912 #ifdef HAVE_TARGET_32_LITTLE
913 Dynobj::sized_create_gnu_hash_table<32, false>(hashed_dynsyms,
915 unhashed_dynsym_index,
927 #ifdef HAVE_TARGET_64_BIG
928 Dynobj::sized_create_gnu_hash_table<64, true>(hashed_dynsyms,
930 unhashed_dynsym_index,
939 #ifdef HAVE_TARGET_64_LITTLE
940 Dynobj::sized_create_gnu_hash_table<64, false>(hashed_dynsyms,
942 unhashed_dynsym_index,
954 // Create the actual data for a GNU hash table. This is just a copy
955 // of the code from the old GNU linker.
957 template<int size, bool big_endian>
959 Dynobj::sized_create_gnu_hash_table(
960 const std::vector<Symbol*>& hashed_dynsyms,
961 const std::vector<uint32_t>& dynsym_hashvals,
962 unsigned int unhashed_dynsym_count,
963 unsigned char** pphash,
964 unsigned int* phashlen)
966 if (hashed_dynsyms.empty())
968 // Special case for the empty hash table.
969 unsigned int hashlen = 5 * 4 + size / 8;
970 unsigned char* phash = new unsigned char[hashlen];
972 elfcpp::Swap<32, big_endian>::writeval(phash, 1);
973 // Symbol index above unhashed symbols.
974 elfcpp::Swap<32, big_endian>::writeval(phash + 4, unhashed_dynsym_count);
975 // One word for bitmask.
976 elfcpp::Swap<32, big_endian>::writeval(phash + 8, 1);
977 // Only bloom filter.
978 elfcpp::Swap<32, big_endian>::writeval(phash + 12, 0);
980 elfcpp::Swap<size, big_endian>::writeval(phash + 16, 0);
981 // No hashes in only bucket.
982 elfcpp::Swap<32, big_endian>::writeval(phash + 16 + size / 8, 0);
990 const unsigned int bucketcount =
991 Dynobj::compute_bucket_count(dynsym_hashvals, true);
993 const unsigned int nsyms = hashed_dynsyms.size();
995 uint32_t maskbitslog2 = 1;
996 uint32_t x = nsyms >> 1;
1002 if (maskbitslog2 < 3)
1004 else if (((1U << (maskbitslog2 - 2)) & nsyms) != 0)
1014 if (maskbitslog2 == 5)
1018 uint32_t mask = (1U << shift1) - 1U;
1019 uint32_t shift2 = maskbitslog2;
1020 uint32_t maskbits = 1U << maskbitslog2;
1021 uint32_t maskwords = 1U << (maskbitslog2 - shift1);
1023 typedef typename elfcpp::Elf_types<size>::Elf_WXword Word;
1024 std::vector<Word> bitmask(maskwords);
1025 std::vector<uint32_t> counts(bucketcount);
1026 std::vector<uint32_t> indx(bucketcount);
1027 uint32_t symindx = unhashed_dynsym_count;
1029 // Count the number of times each hash bucket is used.
1030 for (unsigned int i = 0; i < nsyms; ++i)
1031 ++counts[dynsym_hashvals[i] % bucketcount];
1033 unsigned int cnt = symindx;
1034 for (unsigned int i = 0; i < bucketcount; ++i)
1040 unsigned int hashlen = (4 + bucketcount + nsyms) * 4;
1041 hashlen += maskbits / 8;
1042 unsigned char* phash = new unsigned char[hashlen];
1044 elfcpp::Swap<32, big_endian>::writeval(phash, bucketcount);
1045 elfcpp::Swap<32, big_endian>::writeval(phash + 4, symindx);
1046 elfcpp::Swap<32, big_endian>::writeval(phash + 8, maskwords);
1047 elfcpp::Swap<32, big_endian>::writeval(phash + 12, shift2);
1049 unsigned char* p = phash + 16 + maskbits / 8;
1050 for (unsigned int i = 0; i < bucketcount; ++i)
1053 elfcpp::Swap<32, big_endian>::writeval(p, 0);
1055 elfcpp::Swap<32, big_endian>::writeval(p, indx[i]);
1059 for (unsigned int i = 0; i < nsyms; ++i)
1061 Symbol* sym = hashed_dynsyms[i];
1062 uint32_t hashval = dynsym_hashvals[i];
1064 unsigned int bucket = hashval % bucketcount;
1065 unsigned int val = ((hashval >> shift1)
1066 & ((maskbits >> shift1) - 1));
1067 bitmask[val] |= (static_cast<Word>(1U)) << (hashval & mask);
1068 bitmask[val] |= (static_cast<Word>(1U)) << ((hashval >> shift2) & mask);
1069 val = hashval & ~ 1U;
1070 if (counts[bucket] == 1)
1072 // Last element terminates the chain.
1075 elfcpp::Swap<32, big_endian>::writeval(p + (indx[bucket] - symindx) * 4,
1079 sym->set_dynsym_index(indx[bucket]);
1084 for (unsigned int i = 0; i < maskwords; ++i)
1086 elfcpp::Swap<size, big_endian>::writeval(p, bitmask[i]);
1090 *phashlen = hashlen;
1096 // Write this definition to a buffer for the output section.
1098 template<int size, bool big_endian>
1100 Verdef::write(const Stringpool* dynpool, bool is_last, unsigned char* pb
1101 ACCEPT_SIZE_ENDIAN) const
1103 const int verdef_size = elfcpp::Elf_sizes<size>::verdef_size;
1104 const int verdaux_size = elfcpp::Elf_sizes<size>::verdaux_size;
1106 elfcpp::Verdef_write<size, big_endian> vd(pb);
1107 vd.set_vd_version(elfcpp::VER_DEF_CURRENT);
1108 vd.set_vd_flags((this->is_base_ ? elfcpp::VER_FLG_BASE : 0)
1109 | (this->is_weak_ ? elfcpp::VER_FLG_WEAK : 0));
1110 vd.set_vd_ndx(this->index());
1111 vd.set_vd_cnt(1 + this->deps_.size());
1112 vd.set_vd_hash(Dynobj::elf_hash(this->name()));
1113 vd.set_vd_aux(verdef_size);
1114 vd.set_vd_next(is_last
1116 : verdef_size + (1 + this->deps_.size()) * verdaux_size);
1119 elfcpp::Verdaux_write<size, big_endian> vda(pb);
1120 vda.set_vda_name(dynpool->get_offset(this->name()));
1121 vda.set_vda_next(this->deps_.empty() ? 0 : verdaux_size);
1124 Deps::const_iterator p;
1126 for (p = this->deps_.begin(), i = 0;
1127 p != this->deps_.end();
1130 elfcpp::Verdaux_write<size, big_endian> vda(pb);
1131 vda.set_vda_name(dynpool->get_offset(*p));
1132 vda.set_vda_next(i + 1 >= this->deps_.size() ? 0 : verdaux_size);
1143 for (Need_versions::iterator p = this->need_versions_.begin();
1144 p != this->need_versions_.end();
1149 // Add a new version to this file reference.
1152 Verneed::add_name(const char* name)
1154 Verneed_version* vv = new Verneed_version(name);
1155 this->need_versions_.push_back(vv);
1159 // Set the version indexes starting at INDEX.
1162 Verneed::finalize(unsigned int index)
1164 for (Need_versions::iterator p = this->need_versions_.begin();
1165 p != this->need_versions_.end();
1168 (*p)->set_index(index);
1174 // Write this list of referenced versions to a buffer for the output
1177 template<int size, bool big_endian>
1179 Verneed::write(const Stringpool* dynpool, bool is_last,
1180 unsigned char* pb ACCEPT_SIZE_ENDIAN) const
1182 const int verneed_size = elfcpp::Elf_sizes<size>::verneed_size;
1183 const int vernaux_size = elfcpp::Elf_sizes<size>::vernaux_size;
1185 elfcpp::Verneed_write<size, big_endian> vn(pb);
1186 vn.set_vn_version(elfcpp::VER_NEED_CURRENT);
1187 vn.set_vn_cnt(this->need_versions_.size());
1188 vn.set_vn_file(dynpool->get_offset(this->filename()));
1189 vn.set_vn_aux(verneed_size);
1190 vn.set_vn_next(is_last
1192 : verneed_size + this->need_versions_.size() * vernaux_size);
1195 Need_versions::const_iterator p;
1197 for (p = this->need_versions_.begin(), i = 0;
1198 p != this->need_versions_.end();
1201 elfcpp::Vernaux_write<size, big_endian> vna(pb);
1202 vna.set_vna_hash(Dynobj::elf_hash((*p)->version()));
1203 // FIXME: We need to sometimes set VER_FLG_WEAK here.
1204 vna.set_vna_flags(0);
1205 vna.set_vna_other((*p)->index());
1206 vna.set_vna_name(dynpool->get_offset((*p)->version()));
1207 vna.set_vna_next(i + 1 >= this->need_versions_.size()
1216 // Versions methods.
1218 Versions::~Versions()
1220 for (Defs::iterator p = this->defs_.begin();
1221 p != this->defs_.end();
1225 for (Needs::iterator p = this->needs_.begin();
1226 p != this->needs_.end();
1231 // Return the dynamic object which a symbol refers to.
1234 Versions::get_dynobj_for_sym(const Symbol_table* symtab,
1235 const Symbol* sym) const
1237 if (sym->is_copied_from_dynobj())
1238 return symtab->get_copy_source(sym);
1241 Object* object = sym->object();
1242 gold_assert(object->is_dynamic());
1243 return static_cast<Dynobj*>(object);
1247 // Record version information for a symbol going into the dynamic
1251 Versions::record_version(const Symbol_table* symtab,
1252 Stringpool* dynpool, const Symbol* sym)
1254 gold_assert(!this->is_finalized_);
1255 gold_assert(sym->version() != NULL);
1257 Stringpool::Key version_key;
1258 const char* version = dynpool->add(sym->version(), false, &version_key);
1260 if (!sym->is_from_dynobj() && !sym->is_copied_from_dynobj())
1262 if (parameters->output_is_shared())
1263 this->add_def(sym, version, version_key);
1267 // This is a version reference.
1268 Dynobj* dynobj = this->get_dynobj_for_sym(symtab, sym);
1269 this->add_need(dynpool, dynobj->soname(), version, version_key);
1273 // We've found a symbol SYM defined in version VERSION.
1276 Versions::add_def(const Symbol* sym, const char* version,
1277 Stringpool::Key version_key)
1279 Key k(version_key, 0);
1280 Version_base* const vbnull = NULL;
1281 std::pair<Version_table::iterator, bool> ins =
1282 this->version_table_.insert(std::make_pair(k, vbnull));
1286 // We already have an entry for this version.
1287 Version_base* vb = ins.first->second;
1289 // We have now seen a symbol in this version, so it is not
1293 // FIXME: When we support version scripts, we will need to
1294 // check whether this symbol should be forced local.
1298 // If we are creating a shared object, it is an error to
1299 // find a definition of a symbol with a version which is not
1300 // in the version script.
1301 if (parameters->output_is_shared())
1303 gold_error(_("symbol %s has undefined version %s"),
1304 sym->name(), version);
1308 // If this is the first version we are defining, first define
1309 // the base version. FIXME: Should use soname here when
1310 // creating a shared object.
1311 Verdef* vdbase = new Verdef(parameters->output_file_name(), true, false,
1313 this->defs_.push_back(vdbase);
1315 // When creating a regular executable, automatically define
1317 Verdef* vd = new Verdef(version, false, false, false);
1318 this->defs_.push_back(vd);
1319 ins.first->second = vd;
1323 // Add a reference to version NAME in file FILENAME.
1326 Versions::add_need(Stringpool* dynpool, const char* filename, const char* name,
1327 Stringpool::Key name_key)
1329 Stringpool::Key filename_key;
1330 filename = dynpool->add(filename, true, &filename_key);
1332 Key k(name_key, filename_key);
1333 Version_base* const vbnull = NULL;
1334 std::pair<Version_table::iterator, bool> ins =
1335 this->version_table_.insert(std::make_pair(k, vbnull));
1339 // We already have an entry for this filename/version.
1343 // See whether we already have this filename. We don't expect many
1344 // version references, so we just do a linear search. This could be
1345 // replaced by a hash table.
1347 for (Needs::iterator p = this->needs_.begin();
1348 p != this->needs_.end();
1351 if ((*p)->filename() == filename)
1360 // We have a new filename.
1361 vn = new Verneed(filename);
1362 this->needs_.push_back(vn);
1365 ins.first->second = vn->add_name(name);
1368 // Set the version indexes. Create a new dynamic version symbol for
1369 // each new version definition.
1372 Versions::finalize(const Target* target, Symbol_table* symtab,
1373 unsigned int dynsym_index, std::vector<Symbol*>* syms)
1375 gold_assert(!this->is_finalized_);
1377 unsigned int vi = 1;
1379 for (Defs::iterator p = this->defs_.begin();
1380 p != this->defs_.end();
1383 (*p)->set_index(vi);
1386 // Create a version symbol if necessary.
1387 if (!(*p)->is_symbol_created())
1389 Symbol* vsym = symtab->define_as_constant(target, (*p)->name(),
1393 elfcpp::STV_DEFAULT, 0,
1395 vsym->set_needs_dynsym_entry();
1396 vsym->set_dynsym_index(dynsym_index);
1398 syms->push_back(vsym);
1399 // The name is already in the dynamic pool.
1403 // Index 1 is used for global symbols.
1406 gold_assert(this->defs_.empty());
1410 for (Needs::iterator p = this->needs_.begin();
1411 p != this->needs_.end();
1413 vi = (*p)->finalize(vi);
1415 this->is_finalized_ = true;
1417 return dynsym_index;
1420 // Return the version index to use for a symbol. This does two hash
1421 // table lookups: one in DYNPOOL and one in this->version_table_.
1422 // Another approach alternative would be store a pointer in SYM, which
1423 // would increase the size of the symbol table. Or perhaps we could
1424 // use a hash table from dynamic symbol pointer values to Version_base
1428 Versions::version_index(const Symbol_table* symtab, const Stringpool* dynpool,
1429 const Symbol* sym) const
1431 Stringpool::Key version_key;
1432 const char* version = dynpool->find(sym->version(), &version_key);
1433 gold_assert(version != NULL);
1436 if (!sym->is_from_dynobj() && !sym->is_copied_from_dynobj())
1438 if (!parameters->output_is_shared())
1439 return elfcpp::VER_NDX_GLOBAL;
1440 k = Key(version_key, 0);
1444 Dynobj* dynobj = this->get_dynobj_for_sym(symtab, sym);
1446 Stringpool::Key filename_key;
1447 const char* filename = dynpool->find(dynobj->soname(), &filename_key);
1448 gold_assert(filename != NULL);
1450 k = Key(version_key, filename_key);
1453 Version_table::const_iterator p = this->version_table_.find(k);
1454 gold_assert(p != this->version_table_.end());
1456 return p->second->index();
1459 // Return an allocated buffer holding the contents of the symbol
1462 template<int size, bool big_endian>
1464 Versions::symbol_section_contents(const Symbol_table* symtab,
1465 const Stringpool* dynpool,
1466 unsigned int local_symcount,
1467 const std::vector<Symbol*>& syms,
1470 ACCEPT_SIZE_ENDIAN) const
1472 gold_assert(this->is_finalized_);
1474 unsigned int sz = (local_symcount + syms.size()) * 2;
1475 unsigned char* pbuf = new unsigned char[sz];
1477 for (unsigned int i = 0; i < local_symcount; ++i)
1478 elfcpp::Swap<16, big_endian>::writeval(pbuf + i * 2,
1479 elfcpp::VER_NDX_LOCAL);
1481 for (std::vector<Symbol*>::const_iterator p = syms.begin();
1485 unsigned int version_index;
1486 const char* version = (*p)->version();
1487 if (version == NULL)
1488 version_index = elfcpp::VER_NDX_GLOBAL;
1490 version_index = this->version_index(symtab, dynpool, *p);
1491 elfcpp::Swap<16, big_endian>::writeval(pbuf + (*p)->dynsym_index() * 2,
1499 // Return an allocated buffer holding the contents of the version
1500 // definition section.
1502 template<int size, bool big_endian>
1504 Versions::def_section_contents(const Stringpool* dynpool,
1505 unsigned char** pp, unsigned int* psize,
1506 unsigned int* pentries
1507 ACCEPT_SIZE_ENDIAN) const
1509 gold_assert(this->is_finalized_);
1510 gold_assert(!this->defs_.empty());
1512 const int verdef_size = elfcpp::Elf_sizes<size>::verdef_size;
1513 const int verdaux_size = elfcpp::Elf_sizes<size>::verdaux_size;
1515 unsigned int sz = 0;
1516 for (Defs::const_iterator p = this->defs_.begin();
1517 p != this->defs_.end();
1520 sz += verdef_size + verdaux_size;
1521 sz += (*p)->count_dependencies() * verdaux_size;
1524 unsigned char* pbuf = new unsigned char[sz];
1526 unsigned char* pb = pbuf;
1527 Defs::const_iterator p;
1529 for (p = this->defs_.begin(), i = 0;
1530 p != this->defs_.end();
1532 pb = (*p)->write SELECT_SIZE_ENDIAN_NAME(size, big_endian)(
1533 dynpool, i + 1 >= this->defs_.size(), pb
1534 SELECT_SIZE_ENDIAN(size, big_endian));
1536 gold_assert(static_cast<unsigned int>(pb - pbuf) == sz);
1540 *pentries = this->defs_.size();
1543 // Return an allocated buffer holding the contents of the version
1544 // reference section.
1546 template<int size, bool big_endian>
1548 Versions::need_section_contents(const Stringpool* dynpool,
1549 unsigned char** pp, unsigned int *psize,
1550 unsigned int *pentries
1551 ACCEPT_SIZE_ENDIAN) const
1553 gold_assert(this->is_finalized_);
1554 gold_assert(!this->needs_.empty());
1556 const int verneed_size = elfcpp::Elf_sizes<size>::verneed_size;
1557 const int vernaux_size = elfcpp::Elf_sizes<size>::vernaux_size;
1559 unsigned int sz = 0;
1560 for (Needs::const_iterator p = this->needs_.begin();
1561 p != this->needs_.end();
1565 sz += (*p)->count_versions() * vernaux_size;
1568 unsigned char* pbuf = new unsigned char[sz];
1570 unsigned char* pb = pbuf;
1571 Needs::const_iterator p;
1573 for (p = this->needs_.begin(), i = 0;
1574 p != this->needs_.end();
1576 pb = (*p)->write SELECT_SIZE_ENDIAN_NAME(size, big_endian)(
1577 dynpool, i + 1 >= this->needs_.size(), pb
1578 SELECT_SIZE_ENDIAN(size, big_endian));
1580 gold_assert(static_cast<unsigned int>(pb - pbuf) == sz);
1584 *pentries = this->needs_.size();
1587 // Instantiate the templates we need. We could use the configure
1588 // script to restrict this to only the ones for implemented targets.
1590 #ifdef HAVE_TARGET_32_LITTLE
1592 class Sized_dynobj<32, false>;
1595 #ifdef HAVE_TARGET_32_BIG
1597 class Sized_dynobj<32, true>;
1600 #ifdef HAVE_TARGET_64_LITTLE
1602 class Sized_dynobj<64, false>;
1605 #ifdef HAVE_TARGET_64_BIG
1607 class Sized_dynobj<64, true>;
1610 #ifdef HAVE_TARGET_32_LITTLE
1613 Versions::symbol_section_contents<32, false>(
1614 const Symbol_table*,
1617 const std::vector<Symbol*>&,
1620 ACCEPT_SIZE_ENDIAN_EXPLICIT(32, false)) const;
1623 #ifdef HAVE_TARGET_32_BIG
1626 Versions::symbol_section_contents<32, true>(
1627 const Symbol_table*,
1630 const std::vector<Symbol*>&,
1633 ACCEPT_SIZE_ENDIAN_EXPLICIT(32, true)) const;
1636 #ifdef HAVE_TARGET_64_LITTLE
1639 Versions::symbol_section_contents<64, false>(
1640 const Symbol_table*,
1643 const std::vector<Symbol*>&,
1646 ACCEPT_SIZE_ENDIAN_EXPLICIT(64, false)) const;
1649 #ifdef HAVE_TARGET_64_BIG
1652 Versions::symbol_section_contents<64, true>(
1653 const Symbol_table*,
1656 const std::vector<Symbol*>&,
1659 ACCEPT_SIZE_ENDIAN_EXPLICIT(64, true)) const;
1662 #ifdef HAVE_TARGET_32_LITTLE
1665 Versions::def_section_contents<32, false>(
1670 ACCEPT_SIZE_ENDIAN_EXPLICIT(32, false)) const;
1673 #ifdef HAVE_TARGET_32_BIG
1676 Versions::def_section_contents<32, true>(
1681 ACCEPT_SIZE_ENDIAN_EXPLICIT(32, true)) const;
1684 #ifdef HAVE_TARGET_64_LITTLE
1687 Versions::def_section_contents<64, false>(
1692 ACCEPT_SIZE_ENDIAN_EXPLICIT(64, false)) const;
1695 #ifdef HAVE_TARGET_64_BIG
1698 Versions::def_section_contents<64, true>(
1703 ACCEPT_SIZE_ENDIAN_EXPLICIT(64, true)) const;
1706 #ifdef HAVE_TARGET_32_LITTLE
1709 Versions::need_section_contents<32, false>(
1714 ACCEPT_SIZE_ENDIAN_EXPLICIT(32, false)) const;
1717 #ifdef HAVE_TARGET_32_BIG
1720 Versions::need_section_contents<32, true>(
1725 ACCEPT_SIZE_ENDIAN_EXPLICIT(32, true)) const;
1728 #ifdef HAVE_TARGET_64_LITTLE
1731 Versions::need_section_contents<64, false>(
1736 ACCEPT_SIZE_ENDIAN_EXPLICIT(64, false)) const;
1739 #ifdef HAVE_TARGET_64_BIG
1742 Versions::need_section_contents<64, true>(
1747 ACCEPT_SIZE_ENDIAN_EXPLICIT(64, true)) const;
1750 } // End namespace gold.