// object.cc -- support for an object file for linking in gold // Copyright 2006, 2007, 2008 Free Software Foundation, Inc. // Written by Ian Lance Taylor . // This file is part of gold. // This program is free software; you can redistribute it and/or modify // it under the terms of the GNU General Public License as published by // the Free Software Foundation; either version 3 of the License, or // (at your option) any later version. // This program is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // You should have received a copy of the GNU General Public License // along with this program; if not, write to the Free Software // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, // MA 02110-1301, USA. #include "gold.h" #include #include #include #include "demangle.h" #include "libiberty.h" #include "target-select.h" #include "dwarf_reader.h" #include "layout.h" #include "output.h" #include "symtab.h" #include "reloc.h" #include "object.h" #include "dynobj.h" namespace gold { // Class Object. // Set the target based on fields in the ELF file header. void Object::set_target(int machine, int size, bool big_endian, int osabi, int abiversion) { Target* target = select_target(machine, size, big_endian, osabi, abiversion); if (target == NULL) gold_fatal(_("%s: unsupported ELF machine number %d"), this->name().c_str(), machine); this->target_ = target; } // Report an error for this object file. This is used by the // elfcpp::Elf_file interface, and also called by the Object code // itself. void Object::error(const char* format, ...) const { va_list args; va_start(args, format); char* buf = NULL; if (vasprintf(&buf, format, args) < 0) gold_nomem(); va_end(args); gold_error(_("%s: %s"), this->name().c_str(), buf); free(buf); } // Return a view of the contents of a section. const unsigned char* Object::section_contents(unsigned int shndx, section_size_type* plen, bool cache) { Location loc(this->do_section_contents(shndx)); *plen = convert_to_section_size_type(loc.data_size); return this->get_view(loc.file_offset, *plen, cache); } // Read the section data into SD. This is code common to Sized_relobj // and Sized_dynobj, so we put it into Object. template void Object::read_section_data(elfcpp::Elf_file* elf_file, Read_symbols_data* sd) { const int shdr_size = elfcpp::Elf_sizes::shdr_size; // Read the section headers. const off_t shoff = elf_file->shoff(); const unsigned int shnum = this->shnum(); sd->section_headers = this->get_lasting_view(shoff, shnum * shdr_size, true); // Read the section names. const unsigned char* pshdrs = sd->section_headers->data(); const unsigned char* pshdrnames = pshdrs + elf_file->shstrndx() * shdr_size; typename elfcpp::Shdr shdrnames(pshdrnames); if (shdrnames.get_sh_type() != elfcpp::SHT_STRTAB) this->error(_("section name section has wrong type: %u"), static_cast(shdrnames.get_sh_type())); sd->section_names_size = convert_to_section_size_type(shdrnames.get_sh_size()); sd->section_names = this->get_lasting_view(shdrnames.get_sh_offset(), sd->section_names_size, false); } // If NAME is the name of a special .gnu.warning section, arrange for // the warning to be issued. SHNDX is the section index. Return // whether it is a warning section. bool Object::handle_gnu_warning_section(const char* name, unsigned int shndx, Symbol_table* symtab) { const char warn_prefix[] = ".gnu.warning."; const int warn_prefix_len = sizeof warn_prefix - 1; if (strncmp(name, warn_prefix, warn_prefix_len) == 0) { // Read the section contents to get the warning text. It would // be nicer if we only did this if we have to actually issue a // warning. Unfortunately, warnings are issued as we relocate // sections. That means that we can not lock the object then, // as we might try to issue the same warning multiple times // simultaneously. section_size_type len; const unsigned char* contents = this->section_contents(shndx, &len, false); std::string warning(reinterpret_cast(contents), len); symtab->add_warning(name + warn_prefix_len, this, warning); return true; } return false; } // Class Sized_relobj. template Sized_relobj::Sized_relobj( const std::string& name, Input_file* input_file, off_t offset, const elfcpp::Ehdr& ehdr) : Relobj(name, input_file, offset), elf_file_(this, ehdr), symtab_shndx_(-1U), local_symbol_count_(0), output_local_symbol_count_(0), output_local_dynsym_count_(0), symbols_(), local_symbol_offset_(0), local_dynsym_offset_(0), local_values_(), local_got_offsets_(), has_eh_frame_(false) { } template Sized_relobj::~Sized_relobj() { } // Set up an object file based on the file header. This sets up the // target and reads the section information. template void Sized_relobj::setup( const elfcpp::Ehdr& ehdr) { this->set_target(ehdr.get_e_machine(), size, big_endian, ehdr.get_e_ident()[elfcpp::EI_OSABI], ehdr.get_e_ident()[elfcpp::EI_ABIVERSION]); const unsigned int shnum = this->elf_file_.shnum(); this->set_shnum(shnum); } // Find the SHT_SYMTAB section, given the section headers. The ELF // standard says that maybe in the future there can be more than one // SHT_SYMTAB section. Until somebody figures out how that could // work, we assume there is only one. template void Sized_relobj::find_symtab(const unsigned char* pshdrs) { const unsigned int shnum = this->shnum(); this->symtab_shndx_ = 0; if (shnum > 0) { // Look through the sections in reverse order, since gas tends // to put the symbol table at the end. const unsigned char* p = pshdrs + shnum * This::shdr_size; unsigned int i = shnum; while (i > 0) { --i; p -= This::shdr_size; typename This::Shdr shdr(p); if (shdr.get_sh_type() == elfcpp::SHT_SYMTAB) { this->symtab_shndx_ = i; break; } } } } // Return whether SHDR has the right type and flags to be a GNU // .eh_frame section. template bool Sized_relobj::check_eh_frame_flags( const elfcpp::Shdr* shdr) const { return (shdr->get_sh_size() > 0 && shdr->get_sh_type() == elfcpp::SHT_PROGBITS && (shdr->get_sh_flags() & elfcpp::SHF_ALLOC) != 0); } // Return whether there is a GNU .eh_frame section, given the section // headers and the section names. template bool Sized_relobj::find_eh_frame( const unsigned char* pshdrs, const char* names, section_size_type names_size) const { const unsigned int shnum = this->shnum(); const unsigned char* p = pshdrs + This::shdr_size; for (unsigned int i = 1; i < shnum; ++i, p += This::shdr_size) { typename This::Shdr shdr(p); if (this->check_eh_frame_flags(&shdr)) { if (shdr.get_sh_name() >= names_size) { this->error(_("bad section name offset for section %u: %lu"), i, static_cast(shdr.get_sh_name())); continue; } const char* name = names + shdr.get_sh_name(); if (strcmp(name, ".eh_frame") == 0) return true; } } return false; } // Read the sections and symbols from an object file. template void Sized_relobj::do_read_symbols(Read_symbols_data* sd) { this->read_section_data(&this->elf_file_, sd); const unsigned char* const pshdrs = sd->section_headers->data(); this->find_symtab(pshdrs); const unsigned char* namesu = sd->section_names->data(); const char* names = reinterpret_cast(namesu); if (memmem(names, sd->section_names_size, ".eh_frame", 10) != NULL) { if (this->find_eh_frame(pshdrs, names, sd->section_names_size)) this->has_eh_frame_ = true; } sd->symbols = NULL; sd->symbols_size = 0; sd->external_symbols_offset = 0; sd->symbol_names = NULL; sd->symbol_names_size = 0; if (this->symtab_shndx_ == 0) { // No symbol table. Weird but legal. return; } // Get the symbol table section header. typename This::Shdr symtabshdr(pshdrs + this->symtab_shndx_ * This::shdr_size); gold_assert(symtabshdr.get_sh_type() == elfcpp::SHT_SYMTAB); // If this object has a .eh_frame section, we need all the symbols. // Otherwise we only need the external symbols. While it would be // simpler to just always read all the symbols, I've seen object // files with well over 2000 local symbols, which for a 64-bit // object file format is over 5 pages that we don't need to read // now. const int sym_size = This::sym_size; const unsigned int loccount = symtabshdr.get_sh_info(); this->local_symbol_count_ = loccount; this->local_values_.resize(loccount); section_offset_type locsize = loccount * sym_size; off_t dataoff = symtabshdr.get_sh_offset(); section_size_type datasize = convert_to_section_size_type(symtabshdr.get_sh_size()); off_t extoff = dataoff + locsize; section_size_type extsize = datasize - locsize; off_t readoff = this->has_eh_frame_ ? dataoff : extoff; section_size_type readsize = this->has_eh_frame_ ? datasize : extsize; File_view* fvsymtab = this->get_lasting_view(readoff, readsize, false); // Read the section header for the symbol names. unsigned int strtab_shndx = symtabshdr.get_sh_link(); if (strtab_shndx >= this->shnum()) { this->error(_("invalid symbol table name index: %u"), strtab_shndx); return; } typename This::Shdr strtabshdr(pshdrs + strtab_shndx * This::shdr_size); if (strtabshdr.get_sh_type() != elfcpp::SHT_STRTAB) { this->error(_("symbol table name section has wrong type: %u"), static_cast(strtabshdr.get_sh_type())); return; } // Read the symbol names. File_view* fvstrtab = this->get_lasting_view(strtabshdr.get_sh_offset(), strtabshdr.get_sh_size(), true); sd->symbols = fvsymtab; sd->symbols_size = readsize; sd->external_symbols_offset = this->has_eh_frame_ ? locsize : 0; sd->symbol_names = fvstrtab; sd->symbol_names_size = convert_to_section_size_type(strtabshdr.get_sh_size()); } // Return the section index of symbol SYM. Set *VALUE to its value in // the object file. Note that for a symbol which is not defined in // this object file, this will set *VALUE to 0 and return SHN_UNDEF; // it will not return the final value of the symbol in the link. template unsigned int Sized_relobj::symbol_section_and_value(unsigned int sym, Address* value) { section_size_type symbols_size; const unsigned char* symbols = this->section_contents(this->symtab_shndx_, &symbols_size, false); const size_t count = symbols_size / This::sym_size; gold_assert(sym < count); elfcpp::Sym elfsym(symbols + sym * This::sym_size); *value = elfsym.get_st_value(); // FIXME: Handle SHN_XINDEX. return elfsym.get_st_shndx(); } // Return whether to include a section group in the link. LAYOUT is // used to keep track of which section groups we have already seen. // INDEX is the index of the section group and SHDR is the section // header. If we do not want to include this group, we set bits in // OMIT for each section which should be discarded. template bool Sized_relobj::include_section_group( Symbol_table* symtab, Layout* layout, unsigned int index, const char* name, const elfcpp::Shdr& shdr, std::vector* omit) { // Read the section contents. const unsigned char* pcon = this->get_view(shdr.get_sh_offset(), shdr.get_sh_size(), false); const elfcpp::Elf_Word* pword = reinterpret_cast(pcon); // The first word contains flags. We only care about COMDAT section // groups. Other section groups are always included in the link // just like ordinary sections. elfcpp::Elf_Word flags = elfcpp::Swap<32, big_endian>::readval(pword); // Look up the group signature, which is the name of a symbol. This // is a lot of effort to go to to read a string. Why didn't they // just have the group signature point into the string table, rather // than indirect through a symbol? // Get the appropriate symbol table header (this will normally be // the single SHT_SYMTAB section, but in principle it need not be). const unsigned int link = shdr.get_sh_link(); typename This::Shdr symshdr(this, this->elf_file_.section_header(link)); // Read the symbol table entry. if (shdr.get_sh_info() >= symshdr.get_sh_size() / This::sym_size) { this->error(_("section group %u info %u out of range"), index, shdr.get_sh_info()); return false; } off_t symoff = symshdr.get_sh_offset() + shdr.get_sh_info() * This::sym_size; const unsigned char* psym = this->get_view(symoff, This::sym_size, false); elfcpp::Sym sym(psym); // Read the symbol table names. section_size_type symnamelen; const unsigned char* psymnamesu; psymnamesu = this->section_contents(symshdr.get_sh_link(), &symnamelen, true); const char* psymnames = reinterpret_cast(psymnamesu); // Get the section group signature. if (sym.get_st_name() >= symnamelen) { this->error(_("symbol %u name offset %u out of range"), shdr.get_sh_info(), sym.get_st_name()); return false; } const char* signature = psymnames + sym.get_st_name(); // It seems that some versions of gas will create a section group // associated with a section symbol, and then fail to give a name to // the section symbol. In such a case, use the name of the section. // FIXME. std::string secname; if (signature[0] == '\0' && sym.get_st_type() == elfcpp::STT_SECTION) { secname = this->section_name(sym.get_st_shndx()); signature = secname.c_str(); } // Record this section group, and see whether we've already seen one // with the same signature. if ((flags & elfcpp::GRP_COMDAT) == 0 || layout->add_comdat(signature, true)) { if (parameters->options().relocatable()) layout->layout_group(symtab, this, index, name, signature, shdr, pword); return true; } // This is a duplicate. We want to discard the sections in this // group. size_t count = shdr.get_sh_size() / sizeof(elfcpp::Elf_Word); for (size_t i = 1; i < count; ++i) { elfcpp::Elf_Word secnum = elfcpp::Swap<32, big_endian>::readval(pword + i); if (secnum >= this->shnum()) { this->error(_("section %u in section group %u out of range"), secnum, index); continue; } (*omit)[secnum] = true; } return false; } // Whether to include a linkonce section in the link. NAME is the // name of the section and SHDR is the section header. // Linkonce sections are a GNU extension implemented in the original // GNU linker before section groups were defined. The semantics are // that we only include one linkonce section with a given name. The // name of a linkonce section is normally .gnu.linkonce.T.SYMNAME, // where T is the type of section and SYMNAME is the name of a symbol. // In an attempt to make linkonce sections interact well with section // groups, we try to identify SYMNAME and use it like a section group // signature. We want to block section groups with that signature, // but not other linkonce sections with that signature. We also use // the full name of the linkonce section as a normal section group // signature. template bool Sized_relobj::include_linkonce_section( Layout* layout, const char* name, const elfcpp::Shdr&) { // In general the symbol name we want will be the string following // the last '.'. However, we have to handle the case of // .gnu.linkonce.t.__i686.get_pc_thunk.bx, which was generated by // some versions of gcc. So we use a heuristic: if the name starts // with ".gnu.linkonce.t.", we use everything after that. Otherwise // we look for the last '.'. We can't always simply skip // ".gnu.linkonce.X", because we have to deal with cases like // ".gnu.linkonce.d.rel.ro.local". const char* const linkonce_t = ".gnu.linkonce.t."; const char* symname; if (strncmp(name, linkonce_t, strlen(linkonce_t)) == 0) symname = name + strlen(linkonce_t); else symname = strrchr(name, '.') + 1; bool include1 = layout->add_comdat(symname, false); bool include2 = layout->add_comdat(name, true); return include1 && include2; } // Lay out the input sections. We walk through the sections and check // whether they should be included in the link. If they should, we // pass them to the Layout object, which will return an output section // and an offset. template void Sized_relobj::do_layout(Symbol_table* symtab, Layout* layout, Read_symbols_data* sd) { const unsigned int shnum = this->shnum(); if (shnum == 0) return; // Get the section headers. const unsigned char* pshdrs = sd->section_headers->data(); // Get the section names. const unsigned char* pnamesu = sd->section_names->data(); const char* pnames = reinterpret_cast(pnamesu); // For each section, record the index of the reloc section if any. // Use 0 to mean that there is no reloc section, -1U to mean that // there is more than one. std::vector reloc_shndx(shnum, 0); std::vector reloc_type(shnum, elfcpp::SHT_NULL); // Skip the first, dummy, section. pshdrs += This::shdr_size; for (unsigned int i = 1; i < shnum; ++i, pshdrs += This::shdr_size) { typename This::Shdr shdr(pshdrs); unsigned int sh_type = shdr.get_sh_type(); if (sh_type == elfcpp::SHT_REL || sh_type == elfcpp::SHT_RELA) { unsigned int target_shndx = shdr.get_sh_info(); if (target_shndx == 0 || target_shndx >= shnum) { this->error(_("relocation section %u has bad info %u"), i, target_shndx); continue; } if (reloc_shndx[target_shndx] != 0) reloc_shndx[target_shndx] = -1U; else { reloc_shndx[target_shndx] = i; reloc_type[target_shndx] = sh_type; } } } std::vector& map_sections(this->map_to_output()); map_sections.resize(shnum); // If we are only linking for symbols, then there is nothing else to // do here. if (this->input_file()->just_symbols()) { delete sd->section_headers; sd->section_headers = NULL; delete sd->section_names; sd->section_names = NULL; return; } // Whether we've seen a .note.GNU-stack section. bool seen_gnu_stack = false; // The flags of a .note.GNU-stack section. uint64_t gnu_stack_flags = 0; // Keep track of which sections to omit. std::vector omit(shnum, false); // Keep track of reloc sections when emitting relocations. const bool relocatable = parameters->options().relocatable(); const bool emit_relocs = (relocatable || parameters->options().emit_relocs()); std::vector reloc_sections; // Keep track of .eh_frame sections. std::vector eh_frame_sections; // Skip the first, dummy, section. pshdrs = sd->section_headers->data() + This::shdr_size; for (unsigned int i = 1; i < shnum; ++i, pshdrs += This::shdr_size) { typename This::Shdr shdr(pshdrs); if (shdr.get_sh_name() >= sd->section_names_size) { this->error(_("bad section name offset for section %u: %lu"), i, static_cast(shdr.get_sh_name())); return; } const char* name = pnames + shdr.get_sh_name(); if (this->handle_gnu_warning_section(name, i, symtab)) { if (!relocatable) omit[i] = true; } // The .note.GNU-stack section is special. It gives the // protection flags that this object file requires for the stack // in memory. if (strcmp(name, ".note.GNU-stack") == 0) { seen_gnu_stack = true; gnu_stack_flags |= shdr.get_sh_flags(); omit[i] = true; } bool discard = omit[i]; if (!discard) { if (shdr.get_sh_type() == elfcpp::SHT_GROUP) { if (!this->include_section_group(symtab, layout, i, name, shdr, &omit)) discard = true; } else if ((shdr.get_sh_flags() & elfcpp::SHF_GROUP) == 0 && Layout::is_linkonce(name)) { if (!this->include_linkonce_section(layout, name, shdr)) discard = true; } } if (discard) { // Do not include this section in the link. map_sections[i].output_section = NULL; continue; } // When doing a relocatable link we are going to copy input // reloc sections into the output. We only want to copy the // ones associated with sections which are not being discarded. // However, we don't know that yet for all sections. So save // reloc sections and process them later. if (emit_relocs && (shdr.get_sh_type() == elfcpp::SHT_REL || shdr.get_sh_type() == elfcpp::SHT_RELA)) { reloc_sections.push_back(i); continue; } if (relocatable && shdr.get_sh_type() == elfcpp::SHT_GROUP) continue; // The .eh_frame section is special. It holds exception frame // information that we need to read in order to generate the // exception frame header. We process these after all the other // sections so that the exception frame reader can reliably // determine which sections are being discarded, and discard the // corresponding information. if (!relocatable && strcmp(name, ".eh_frame") == 0 && this->check_eh_frame_flags(&shdr)) { eh_frame_sections.push_back(i); continue; } off_t offset; Output_section* os = layout->layout(this, i, name, shdr, reloc_shndx[i], reloc_type[i], &offset); map_sections[i].output_section = os; map_sections[i].offset = offset; // If this section requires special handling, and if there are // relocs that apply to it, then we must do the special handling // before we apply the relocs. if (offset == -1 && reloc_shndx[i] != 0) this->set_relocs_must_follow_section_writes(); } layout->layout_gnu_stack(seen_gnu_stack, gnu_stack_flags); // When doing a relocatable link handle the reloc sections at the // end. if (emit_relocs) this->size_relocatable_relocs(); for (std::vector::const_iterator p = reloc_sections.begin(); p != reloc_sections.end(); ++p) { unsigned int i = *p; const unsigned char* pshdr; pshdr = sd->section_headers->data() + i * This::shdr_size; typename This::Shdr shdr(pshdr); unsigned int data_shndx = shdr.get_sh_info(); if (data_shndx >= shnum) { // We already warned about this above. continue; } Output_section* data_section = map_sections[data_shndx].output_section; if (data_section == NULL) { map_sections[i].output_section = NULL; continue; } Relocatable_relocs* rr = new Relocatable_relocs(); this->set_relocatable_relocs(i, rr); Output_section* os = layout->layout_reloc(this, i, shdr, data_section, rr); map_sections[i].output_section = os; map_sections[i].offset = -1; } // Handle the .eh_frame sections at the end. for (std::vector::const_iterator p = eh_frame_sections.begin(); p != eh_frame_sections.end(); ++p) { gold_assert(this->has_eh_frame_); gold_assert(sd->external_symbols_offset != 0); unsigned int i = *p; const unsigned char *pshdr; pshdr = sd->section_headers->data() + i * This::shdr_size; typename This::Shdr shdr(pshdr); off_t offset; Output_section* os = layout->layout_eh_frame(this, sd->symbols->data(), sd->symbols_size, sd->symbol_names->data(), sd->symbol_names_size, i, shdr, reloc_shndx[i], reloc_type[i], &offset); map_sections[i].output_section = os; map_sections[i].offset = offset; // If this section requires special handling, and if there are // relocs that apply to it, then we must do the special handling // before we apply the relocs. if (offset == -1 && reloc_shndx[i] != 0) this->set_relocs_must_follow_section_writes(); } delete sd->section_headers; sd->section_headers = NULL; delete sd->section_names; sd->section_names = NULL; } // Add the symbols to the symbol table. template void Sized_relobj::do_add_symbols(Symbol_table* symtab, Read_symbols_data* sd) { if (sd->symbols == NULL) { gold_assert(sd->symbol_names == NULL); return; } const int sym_size = This::sym_size; size_t symcount = ((sd->symbols_size - sd->external_symbols_offset) / sym_size); if (symcount * sym_size != sd->symbols_size - sd->external_symbols_offset) { this->error(_("size of symbols is not multiple of symbol size")); return; } this->symbols_.resize(symcount); const char* sym_names = reinterpret_cast(sd->symbol_names->data()); symtab->add_from_relobj(this, sd->symbols->data() + sd->external_symbols_offset, symcount, sym_names, sd->symbol_names_size, &this->symbols_); delete sd->symbols; sd->symbols = NULL; delete sd->symbol_names; sd->symbol_names = NULL; } // First pass over the local symbols. Here we add their names to // *POOL and *DYNPOOL, and we store the symbol value in // THIS->LOCAL_VALUES_. This function is always called from a // singleton thread. This is followed by a call to // finalize_local_symbols. template void Sized_relobj::do_count_local_symbols(Stringpool* pool, Stringpool* dynpool) { gold_assert(this->symtab_shndx_ != -1U); if (this->symtab_shndx_ == 0) { // This object has no symbols. Weird but legal. return; } // Read the symbol table section header. const unsigned int symtab_shndx = this->symtab_shndx_; typename This::Shdr symtabshdr(this, this->elf_file_.section_header(symtab_shndx)); gold_assert(symtabshdr.get_sh_type() == elfcpp::SHT_SYMTAB); // Read the local symbols. const int sym_size = This::sym_size; const unsigned int loccount = this->local_symbol_count_; gold_assert(loccount == symtabshdr.get_sh_info()); off_t locsize = loccount * sym_size; const unsigned char* psyms = this->get_view(symtabshdr.get_sh_offset(), locsize, true); // Read the symbol names. const unsigned int strtab_shndx = symtabshdr.get_sh_link(); section_size_type strtab_size; const unsigned char* pnamesu = this->section_contents(strtab_shndx, &strtab_size, true); const char* pnames = reinterpret_cast(pnamesu); // Loop over the local symbols. const std::vector& mo(this->map_to_output()); unsigned int shnum = this->shnum(); unsigned int count = 0; unsigned int dyncount = 0; // Skip the first, dummy, symbol. psyms += sym_size; for (unsigned int i = 1; i < loccount; ++i, psyms += sym_size) { elfcpp::Sym sym(psyms); Symbol_value& lv(this->local_values_[i]); unsigned int shndx = sym.get_st_shndx(); lv.set_input_shndx(shndx); if (sym.get_st_type() == elfcpp::STT_SECTION) lv.set_is_section_symbol(); else if (sym.get_st_type() == elfcpp::STT_TLS) lv.set_is_tls_symbol(); // Save the input symbol value for use in do_finalize_local_symbols(). lv.set_input_value(sym.get_st_value()); // Decide whether this symbol should go into the output file. if (shndx < shnum && mo[shndx].output_section == NULL) { lv.set_no_output_symtab_entry(); gold_assert(!lv.needs_output_dynsym_entry()); continue; } if (sym.get_st_type() == elfcpp::STT_SECTION) { lv.set_no_output_symtab_entry(); gold_assert(!lv.needs_output_dynsym_entry()); continue; } if (sym.get_st_name() >= strtab_size) { this->error(_("local symbol %u section name out of range: %u >= %u"), i, sym.get_st_name(), static_cast(strtab_size)); lv.set_no_output_symtab_entry(); continue; } // Add the symbol to the symbol table string pool. const char* name = pnames + sym.get_st_name(); pool->add(name, true, NULL); ++count; // If needed, add the symbol to the dynamic symbol table string pool. if (lv.needs_output_dynsym_entry()) { dynpool->add(name, true, NULL); ++dyncount; } } this->output_local_symbol_count_ = count; this->output_local_dynsym_count_ = dyncount; } // Finalize the local symbols. Here we set the final value in // THIS->LOCAL_VALUES_ and set their output symbol table indexes. // This function is always called from a singleton thread. The actual // output of the local symbols will occur in a separate task. template unsigned int Sized_relobj::do_finalize_local_symbols(unsigned int index, off_t off) { gold_assert(off == static_cast(align_address(off, size >> 3))); const unsigned int loccount = this->local_symbol_count_; this->local_symbol_offset_ = off; const std::vector& mo(this->map_to_output()); unsigned int shnum = this->shnum(); for (unsigned int i = 1; i < loccount; ++i) { Symbol_value& lv(this->local_values_[i]); unsigned int shndx = lv.input_shndx(); // Set the output symbol value. if (shndx >= elfcpp::SHN_LORESERVE) { if (shndx == elfcpp::SHN_ABS || shndx == elfcpp::SHN_COMMON) lv.set_output_value(lv.input_value()); else { // FIXME: Handle SHN_XINDEX. this->error(_("unknown section index %u for local symbol %u"), shndx, i); lv.set_output_value(0); } } else { if (shndx >= shnum) { this->error(_("local symbol %u section index %u out of range"), i, shndx); shndx = 0; } Output_section* os = mo[shndx].output_section; if (os == NULL) { lv.set_output_value(0); continue; } else if (mo[shndx].offset == -1) { // This is a SHF_MERGE section or one which otherwise // requires special handling. We get the output address // of the start of the merged section. If this is not a // section symbol, we can then determine the final // value. If it is a section symbol, we can not, as in // that case we have to consider the addend to determine // the value to use in a relocation. if (!lv.is_section_symbol()) lv.set_output_value(os->output_address(this, shndx, lv.input_value())); else { section_offset_type start = os->starting_output_address(this, shndx); Merged_symbol_value* msv = new Merged_symbol_value(lv.input_value(), start); lv.set_merged_symbol_value(msv); } } else if (lv.is_tls_symbol()) lv.set_output_value(os->tls_offset() + mo[shndx].offset + lv.input_value()); else lv.set_output_value(os->address() + mo[shndx].offset + lv.input_value()); } if (lv.needs_output_symtab_entry()) { lv.set_output_symtab_index(index); ++index; } } return index; } // Set the output dynamic symbol table indexes for the local variables. template unsigned int Sized_relobj::do_set_local_dynsym_indexes(unsigned int index) { const unsigned int loccount = this->local_symbol_count_; for (unsigned int i = 1; i < loccount; ++i) { Symbol_value& lv(this->local_values_[i]); if (lv.needs_output_dynsym_entry()) { lv.set_output_dynsym_index(index); ++index; } } return index; } // Set the offset where local dynamic symbol information will be stored. // Returns the count of local symbols contributed to the symbol table by // this object. template unsigned int Sized_relobj::do_set_local_dynsym_offset(off_t off) { gold_assert(off == static_cast(align_address(off, size >> 3))); this->local_dynsym_offset_ = off; return this->output_local_dynsym_count_; } // Write out the local symbols. template void Sized_relobj::write_local_symbols( Output_file* of, const Stringpool* sympool, const Stringpool* dynpool) { if (parameters->options().strip_all() && this->output_local_dynsym_count_ == 0) return; gold_assert(this->symtab_shndx_ != -1U); if (this->symtab_shndx_ == 0) { // This object has no symbols. Weird but legal. return; } // Read the symbol table section header. const unsigned int symtab_shndx = this->symtab_shndx_; typename This::Shdr symtabshdr(this, this->elf_file_.section_header(symtab_shndx)); gold_assert(symtabshdr.get_sh_type() == elfcpp::SHT_SYMTAB); const unsigned int loccount = this->local_symbol_count_; gold_assert(loccount == symtabshdr.get_sh_info()); // Read the local symbols. const int sym_size = This::sym_size; off_t locsize = loccount * sym_size; const unsigned char* psyms = this->get_view(symtabshdr.get_sh_offset(), locsize, false); // Read the symbol names. const unsigned int strtab_shndx = symtabshdr.get_sh_link(); section_size_type strtab_size; const unsigned char* pnamesu = this->section_contents(strtab_shndx, &strtab_size, false); const char* pnames = reinterpret_cast(pnamesu); // Get views into the output file for the portions of the symbol table // and the dynamic symbol table that we will be writing. off_t output_size = this->output_local_symbol_count_ * sym_size; unsigned char* oview = NULL; if (output_size > 0) oview = of->get_output_view(this->local_symbol_offset_, output_size); off_t dyn_output_size = this->output_local_dynsym_count_ * sym_size; unsigned char* dyn_oview = NULL; if (dyn_output_size > 0) dyn_oview = of->get_output_view(this->local_dynsym_offset_, dyn_output_size); const std::vector& mo(this->map_to_output()); gold_assert(this->local_values_.size() == loccount); unsigned char* ov = oview; unsigned char* dyn_ov = dyn_oview; psyms += sym_size; for (unsigned int i = 1; i < loccount; ++i, psyms += sym_size) { elfcpp::Sym isym(psyms); unsigned int st_shndx = isym.get_st_shndx(); if (st_shndx < elfcpp::SHN_LORESERVE) { gold_assert(st_shndx < mo.size()); if (mo[st_shndx].output_section == NULL) continue; st_shndx = mo[st_shndx].output_section->out_shndx(); } // Write the symbol to the output symbol table. if (!parameters->options().strip_all() && this->local_values_[i].needs_output_symtab_entry()) { elfcpp::Sym_write osym(ov); gold_assert(isym.get_st_name() < strtab_size); const char* name = pnames + isym.get_st_name(); osym.put_st_name(sympool->get_offset(name)); osym.put_st_value(this->local_values_[i].value(this, 0)); osym.put_st_size(isym.get_st_size()); osym.put_st_info(isym.get_st_info()); osym.put_st_other(isym.get_st_other()); osym.put_st_shndx(st_shndx); ov += sym_size; } // Write the symbol to the output dynamic symbol table. if (this->local_values_[i].needs_output_dynsym_entry()) { gold_assert(dyn_ov < dyn_oview + dyn_output_size); elfcpp::Sym_write osym(dyn_ov); gold_assert(isym.get_st_name() < strtab_size); const char* name = pnames + isym.get_st_name(); osym.put_st_name(dynpool->get_offset(name)); osym.put_st_value(this->local_values_[i].value(this, 0)); osym.put_st_size(isym.get_st_size()); osym.put_st_info(isym.get_st_info()); osym.put_st_other(isym.get_st_other()); osym.put_st_shndx(st_shndx); dyn_ov += sym_size; } } if (output_size > 0) { gold_assert(ov - oview == output_size); of->write_output_view(this->local_symbol_offset_, output_size, oview); } if (dyn_output_size > 0) { gold_assert(dyn_ov - dyn_oview == dyn_output_size); of->write_output_view(this->local_dynsym_offset_, dyn_output_size, dyn_oview); } } // Set *INFO to symbolic information about the offset OFFSET in the // section SHNDX. Return true if we found something, false if we // found nothing. template bool Sized_relobj::get_symbol_location_info( unsigned int shndx, off_t offset, Symbol_location_info* info) { if (this->symtab_shndx_ == 0) return false; section_size_type symbols_size; const unsigned char* symbols = this->section_contents(this->symtab_shndx_, &symbols_size, false); unsigned int symbol_names_shndx = this->section_link(this->symtab_shndx_); section_size_type names_size; const unsigned char* symbol_names_u = this->section_contents(symbol_names_shndx, &names_size, false); const char* symbol_names = reinterpret_cast(symbol_names_u); const int sym_size = This::sym_size; const size_t count = symbols_size / sym_size; const unsigned char* p = symbols; for (size_t i = 0; i < count; ++i, p += sym_size) { elfcpp::Sym sym(p); if (sym.get_st_type() == elfcpp::STT_FILE) { if (sym.get_st_name() >= names_size) info->source_file = "(invalid)"; else info->source_file = symbol_names + sym.get_st_name(); } else if (sym.get_st_shndx() == shndx && static_cast(sym.get_st_value()) <= offset && (static_cast(sym.get_st_value() + sym.get_st_size()) > offset)) { if (sym.get_st_name() > names_size) info->enclosing_symbol_name = "(invalid)"; else { info->enclosing_symbol_name = symbol_names + sym.get_st_name(); if (parameters->options().do_demangle()) { char* demangled_name = cplus_demangle( info->enclosing_symbol_name.c_str(), DMGL_ANSI | DMGL_PARAMS); if (demangled_name != NULL) { info->enclosing_symbol_name.assign(demangled_name); free(demangled_name); } } } return true; } } return false; } // Input_objects methods. // Add a regular relocatable object to the list. Return false if this // object should be ignored. bool Input_objects::add_object(Object* obj) { // Set the global target from the first object file we recognize. Target* target = obj->target(); if (!parameters->target_valid()) set_parameters_target(target); else if (target != ¶meters->target()) { obj->error(_("incompatible target")); return false; } if (!obj->is_dynamic()) this->relobj_list_.push_back(static_cast(obj)); else { // See if this is a duplicate SONAME. Dynobj* dynobj = static_cast(obj); const char* soname = dynobj->soname(); std::pair::iterator, bool> ins = this->sonames_.insert(soname); if (!ins.second) { // We have already seen a dynamic object with this soname. return false; } this->dynobj_list_.push_back(dynobj); // If this is -lc, remember the directory in which we found it. // We use this when issuing warnings about undefined symbols: as // a heuristic, we don't warn about system libraries found in // the same directory as -lc. if (strncmp(soname, "libc.so", 7) == 0) { const char* object_name = dynobj->name().c_str(); const char* base = lbasename(object_name); if (base != object_name) this->system_library_directory_.assign(object_name, base - 1 - object_name); } } return true; } // Return whether an object was found in the system library directory. bool Input_objects::found_in_system_library_directory(const Object* object) const { return (!this->system_library_directory_.empty() && object->name().compare(0, this->system_library_directory_.size(), this->system_library_directory_) == 0); } // For each dynamic object, record whether we've seen all of its // explicit dependencies. void Input_objects::check_dynamic_dependencies() const { for (Dynobj_list::const_iterator p = this->dynobj_list_.begin(); p != this->dynobj_list_.end(); ++p) { const Dynobj::Needed& needed((*p)->needed()); bool found_all = true; for (Dynobj::Needed::const_iterator pneeded = needed.begin(); pneeded != needed.end(); ++pneeded) { if (this->sonames_.find(*pneeded) == this->sonames_.end()) { found_all = false; break; } } (*p)->set_has_unknown_needed_entries(!found_all); } } // Relocate_info methods. // Return a string describing the location of a relocation. This is // only used in error messages. template std::string Relocate_info::location(size_t, off_t offset) const { // See if we can get line-number information from debugging sections. std::string filename; std::string file_and_lineno; // Better than filename-only, if available. Sized_dwarf_line_info line_info(this->object); // This will be "" if we failed to parse the debug info for any reason. file_and_lineno = line_info.addr2line(this->data_shndx, offset); std::string ret(this->object->name()); ret += ':'; Symbol_location_info info; if (this->object->get_symbol_location_info(this->data_shndx, offset, &info)) { ret += " in function "; ret += info.enclosing_symbol_name; ret += ":"; filename = info.source_file; } if (!file_and_lineno.empty()) ret += file_and_lineno; else { if (!filename.empty()) ret += filename; ret += "("; ret += this->object->section_name(this->data_shndx); char buf[100]; // Offsets into sections have to be positive. snprintf(buf, sizeof(buf), "+0x%lx", static_cast(offset)); ret += buf; ret += ")"; } return ret; } } // End namespace gold. namespace { using namespace gold; // Read an ELF file with the header and return the appropriate // instance of Object. template Object* make_elf_sized_object(const std::string& name, Input_file* input_file, off_t offset, const elfcpp::Ehdr& ehdr) { int et = ehdr.get_e_type(); if (et == elfcpp::ET_REL) { Sized_relobj* obj = new Sized_relobj(name, input_file, offset, ehdr); obj->setup(ehdr); return obj; } else if (et == elfcpp::ET_DYN) { Sized_dynobj* obj = new Sized_dynobj(name, input_file, offset, ehdr); obj->setup(ehdr); return obj; } else { gold_error(_("%s: unsupported ELF file type %d"), name.c_str(), et); return NULL; } } } // End anonymous namespace. namespace gold { // Read an ELF file and return the appropriate instance of Object. Object* make_elf_object(const std::string& name, Input_file* input_file, off_t offset, const unsigned char* p, section_offset_type bytes) { if (bytes < elfcpp::EI_NIDENT) { gold_error(_("%s: ELF file too short"), name.c_str()); return NULL; } int v = p[elfcpp::EI_VERSION]; if (v != elfcpp::EV_CURRENT) { if (v == elfcpp::EV_NONE) gold_error(_("%s: invalid ELF version 0"), name.c_str()); else gold_error(_("%s: unsupported ELF version %d"), name.c_str(), v); return NULL; } int c = p[elfcpp::EI_CLASS]; if (c == elfcpp::ELFCLASSNONE) { gold_error(_("%s: invalid ELF class 0"), name.c_str()); return NULL; } else if (c != elfcpp::ELFCLASS32 && c != elfcpp::ELFCLASS64) { gold_error(_("%s: unsupported ELF class %d"), name.c_str(), c); return NULL; } int d = p[elfcpp::EI_DATA]; if (d == elfcpp::ELFDATANONE) { gold_error(_("%s: invalid ELF data encoding"), name.c_str()); return NULL; } else if (d != elfcpp::ELFDATA2LSB && d != elfcpp::ELFDATA2MSB) { gold_error(_("%s: unsupported ELF data encoding %d"), name.c_str(), d); return NULL; } bool big_endian = d == elfcpp::ELFDATA2MSB; if (c == elfcpp::ELFCLASS32) { if (bytes < elfcpp::Elf_sizes<32>::ehdr_size) { gold_error(_("%s: ELF file too short"), name.c_str()); return NULL; } if (big_endian) { #ifdef HAVE_TARGET_32_BIG elfcpp::Ehdr<32, true> ehdr(p); return make_elf_sized_object<32, true>(name, input_file, offset, ehdr); #else gold_error(_("%s: not configured to support " "32-bit big-endian object"), name.c_str()); return NULL; #endif } else { #ifdef HAVE_TARGET_32_LITTLE elfcpp::Ehdr<32, false> ehdr(p); return make_elf_sized_object<32, false>(name, input_file, offset, ehdr); #else gold_error(_("%s: not configured to support " "32-bit little-endian object"), name.c_str()); return NULL; #endif } } else { if (bytes < elfcpp::Elf_sizes<32>::ehdr_size) { gold_error(_("%s: ELF file too short"), name.c_str()); return NULL; } if (big_endian) { #ifdef HAVE_TARGET_64_BIG elfcpp::Ehdr<64, true> ehdr(p); return make_elf_sized_object<64, true>(name, input_file, offset, ehdr); #else gold_error(_("%s: not configured to support " "64-bit big-endian object"), name.c_str()); return NULL; #endif } else { #ifdef HAVE_TARGET_64_LITTLE elfcpp::Ehdr<64, false> ehdr(p); return make_elf_sized_object<64, false>(name, input_file, offset, ehdr); #else gold_error(_("%s: not configured to support " "64-bit little-endian object"), name.c_str()); return NULL; #endif } } } // Instantiate the templates we need. We could use the configure // script to restrict this to only the ones for implemented targets. #ifdef HAVE_TARGET_32_LITTLE template class Sized_relobj<32, false>; #endif #ifdef HAVE_TARGET_32_BIG template class Sized_relobj<32, true>; #endif #ifdef HAVE_TARGET_64_LITTLE template class Sized_relobj<64, false>; #endif #ifdef HAVE_TARGET_64_BIG template class Sized_relobj<64, true>; #endif #ifdef HAVE_TARGET_32_LITTLE template struct Relocate_info<32, false>; #endif #ifdef HAVE_TARGET_32_BIG template struct Relocate_info<32, true>; #endif #ifdef HAVE_TARGET_64_LITTLE template struct Relocate_info<64, false>; #endif #ifdef HAVE_TARGET_64_BIG template struct Relocate_info<64, true>; #endif } // End namespace gold.