// i386.cc -- i386 target support for gold. // Copyright 2006, 2007 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 "elfcpp.h" #include "parameters.h" #include "reloc.h" #include "i386.h" #include "object.h" #include "symtab.h" #include "layout.h" #include "output.h" #include "target.h" #include "target-reloc.h" #include "target-select.h" #include "tls.h" namespace { using namespace gold; class Output_data_plt_i386; // The i386 target class. // TLS info comes from // http://people.redhat.com/drepper/tls.pdf // http://www.lsd.ic.unicamp.br/~oliva/writeups/TLS/RFC-TLSDESC-x86.txt class Target_i386 : public Sized_target<32, false> { public: typedef Output_data_reloc Reloc_section; Target_i386() : Sized_target<32, false>(&i386_info), got_(NULL), plt_(NULL), got_plt_(NULL), rel_dyn_(NULL), copy_relocs_(NULL), dynbss_(NULL), got_mod_index_offset_(-1U) { } // Scan the relocations to look for symbol adjustments. void scan_relocs(const General_options& options, Symbol_table* symtab, Layout* layout, Sized_relobj<32, false>* object, unsigned int data_shndx, unsigned int sh_type, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, bool needs_special_offset_handling, size_t local_symbol_count, const unsigned char* plocal_symbols); // Finalize the sections. void do_finalize_sections(Layout*); // Return the value to use for a dynamic which requires special // treatment. uint64_t do_dynsym_value(const Symbol*) const; // Relocate a section. void relocate_section(const Relocate_info<32, false>*, unsigned int sh_type, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, bool needs_special_offset_handling, unsigned char* view, elfcpp::Elf_types<32>::Elf_Addr view_address, section_size_type view_size); // Return a string used to fill a code section with nops. std::string do_code_fill(section_size_type length); // Return whether SYM is defined by the ABI. bool do_is_defined_by_abi(Symbol* sym) const { return strcmp(sym->name(), "___tls_get_addr") == 0; } // Return the size of the GOT section. section_size_type got_size() { gold_assert(this->got_ != NULL); return this->got_->data_size(); } private: // The class which scans relocations. struct Scan { inline void local(const General_options& options, Symbol_table* symtab, Layout* layout, Target_i386* target, Sized_relobj<32, false>* object, unsigned int data_shndx, Output_section* output_section, const elfcpp::Rel<32, false>& reloc, unsigned int r_type, const elfcpp::Sym<32, false>& lsym); inline void global(const General_options& options, Symbol_table* symtab, Layout* layout, Target_i386* target, Sized_relobj<32, false>* object, unsigned int data_shndx, Output_section* output_section, const elfcpp::Rel<32, false>& reloc, unsigned int r_type, Symbol* gsym); static void unsupported_reloc_local(Sized_relobj<32, false>*, unsigned int r_type); static void unsupported_reloc_global(Sized_relobj<32, false>*, unsigned int r_type, Symbol*); }; // The class which implements relocation. class Relocate { public: Relocate() : skip_call_tls_get_addr_(false), local_dynamic_type_(LOCAL_DYNAMIC_NONE) { } ~Relocate() { if (this->skip_call_tls_get_addr_) { // FIXME: This needs to specify the location somehow. gold_error(_("missing expected TLS relocation")); } } // Return whether the static relocation needs to be applied. inline bool should_apply_static_reloc(const Sized_symbol<32>* gsym, int ref_flags, bool is_32bit); // Do a relocation. Return false if the caller should not issue // any warnings about this relocation. inline bool relocate(const Relocate_info<32, false>*, Target_i386*, size_t relnum, const elfcpp::Rel<32, false>&, unsigned int r_type, const Sized_symbol<32>*, const Symbol_value<32>*, unsigned char*, elfcpp::Elf_types<32>::Elf_Addr, section_size_type); private: // Do a TLS relocation. inline void relocate_tls(const Relocate_info<32, false>*, Target_i386* target, size_t relnum, const elfcpp::Rel<32, false>&, unsigned int r_type, const Sized_symbol<32>*, const Symbol_value<32>*, unsigned char*, elfcpp::Elf_types<32>::Elf_Addr, section_size_type); // Do a TLS General-Dynamic to Initial-Exec transition. inline void tls_gd_to_ie(const Relocate_info<32, false>*, size_t relnum, Output_segment* tls_segment, const elfcpp::Rel<32, false>&, unsigned int r_type, elfcpp::Elf_types<32>::Elf_Addr value, unsigned char* view, section_size_type view_size); // Do a TLS General-Dynamic to Local-Exec transition. inline void tls_gd_to_le(const Relocate_info<32, false>*, size_t relnum, Output_segment* tls_segment, const elfcpp::Rel<32, false>&, unsigned int r_type, elfcpp::Elf_types<32>::Elf_Addr value, unsigned char* view, section_size_type view_size); // Do a TLS Local-Dynamic to Local-Exec transition. inline void tls_ld_to_le(const Relocate_info<32, false>*, size_t relnum, Output_segment* tls_segment, const elfcpp::Rel<32, false>&, unsigned int r_type, elfcpp::Elf_types<32>::Elf_Addr value, unsigned char* view, section_size_type view_size); // Do a TLS Initial-Exec to Local-Exec transition. static inline void tls_ie_to_le(const Relocate_info<32, false>*, size_t relnum, Output_segment* tls_segment, const elfcpp::Rel<32, false>&, unsigned int r_type, elfcpp::Elf_types<32>::Elf_Addr value, unsigned char* view, section_size_type view_size); // We need to keep track of which type of local dynamic relocation // we have seen, so that we can optimize R_386_TLS_LDO_32 correctly. enum Local_dynamic_type { LOCAL_DYNAMIC_NONE, LOCAL_DYNAMIC_SUN, LOCAL_DYNAMIC_GNU }; // This is set if we should skip the next reloc, which should be a // PLT32 reloc against ___tls_get_addr. bool skip_call_tls_get_addr_; // The type of local dynamic relocation we have seen in the section // being relocated, if any. Local_dynamic_type local_dynamic_type_; }; // Adjust TLS relocation type based on the options and whether this // is a local symbol. static tls::Tls_optimization optimize_tls_reloc(bool is_final, int r_type); // Get the GOT section, creating it if necessary. Output_data_got<32, false>* got_section(Symbol_table*, Layout*); // Get the GOT PLT section. Output_data_space* got_plt_section() const { gold_assert(this->got_plt_ != NULL); return this->got_plt_; } // Create a PLT entry for a global symbol. void make_plt_entry(Symbol_table*, Layout*, Symbol*); // Create a GOT entry for the TLS module index. unsigned int got_mod_index_entry(Symbol_table* symtab, Layout* layout, Sized_relobj<32, false>* object); // Get the PLT section. const Output_data_plt_i386* plt_section() const { gold_assert(this->plt_ != NULL); return this->plt_; } // Get the dynamic reloc section, creating it if necessary. Reloc_section* rel_dyn_section(Layout*); // Return true if the symbol may need a COPY relocation. // References from an executable object to non-function symbols // defined in a dynamic object may need a COPY relocation. bool may_need_copy_reloc(Symbol* gsym) { return (!parameters->output_is_shared() && gsym->is_from_dynobj() && gsym->type() != elfcpp::STT_FUNC); } // Copy a relocation against a global symbol. void copy_reloc(const General_options*, Symbol_table*, Layout*, Sized_relobj<32, false>*, unsigned int, Output_section*, Symbol*, const elfcpp::Rel<32, false>&); // Information about this specific target which we pass to the // general Target structure. static const Target::Target_info i386_info; // The GOT section. Output_data_got<32, false>* got_; // The PLT section. Output_data_plt_i386* plt_; // The GOT PLT section. Output_data_space* got_plt_; // The dynamic reloc section. Reloc_section* rel_dyn_; // Relocs saved to avoid a COPY reloc. Copy_relocs<32, false>* copy_relocs_; // Space for variables copied with a COPY reloc. Output_data_space* dynbss_; // Offset of the GOT entry for the TLS module index; unsigned int got_mod_index_offset_; }; const Target::Target_info Target_i386::i386_info = { 32, // size false, // is_big_endian elfcpp::EM_386, // machine_code false, // has_make_symbol false, // has_resolve true, // has_code_fill true, // is_default_stack_executable "/usr/lib/libc.so.1", // dynamic_linker 0x08048000, // default_text_segment_address 0x1000, // abi_pagesize 0x1000 // common_pagesize }; // Get the GOT section, creating it if necessary. Output_data_got<32, false>* Target_i386::got_section(Symbol_table* symtab, Layout* layout) { if (this->got_ == NULL) { gold_assert(symtab != NULL && layout != NULL); this->got_ = new Output_data_got<32, false>(); layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS, elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE, this->got_); // The old GNU linker creates a .got.plt section. We just // create another set of data in the .got section. Note that we // always create a PLT if we create a GOT, although the PLT // might be empty. this->got_plt_ = new Output_data_space(4); layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS, elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE, this->got_plt_); // The first three entries are reserved. this->got_plt_->set_current_data_size(3 * 4); // Define _GLOBAL_OFFSET_TABLE_ at the start of the PLT. symtab->define_in_output_data("_GLOBAL_OFFSET_TABLE_", NULL, this->got_plt_, 0, 0, elfcpp::STT_OBJECT, elfcpp::STB_LOCAL, elfcpp::STV_HIDDEN, 0, false, false); } return this->got_; } // Get the dynamic reloc section, creating it if necessary. Target_i386::Reloc_section* Target_i386::rel_dyn_section(Layout* layout) { if (this->rel_dyn_ == NULL) { gold_assert(layout != NULL); this->rel_dyn_ = new Reloc_section(); layout->add_output_section_data(".rel.dyn", elfcpp::SHT_REL, elfcpp::SHF_ALLOC, this->rel_dyn_); } return this->rel_dyn_; } // A class to handle the PLT data. class Output_data_plt_i386 : public Output_section_data { public: typedef Output_data_reloc Reloc_section; Output_data_plt_i386(Layout*, Output_data_space*); // Add an entry to the PLT. void add_entry(Symbol* gsym); // Return the .rel.plt section data. const Reloc_section* rel_plt() const { return this->rel_; } protected: void do_adjust_output_section(Output_section* os); private: // The size of an entry in the PLT. static const int plt_entry_size = 16; // The first entry in the PLT for an executable. static unsigned char exec_first_plt_entry[plt_entry_size]; // The first entry in the PLT for a shared object. static unsigned char dyn_first_plt_entry[plt_entry_size]; // Other entries in the PLT for an executable. static unsigned char exec_plt_entry[plt_entry_size]; // Other entries in the PLT for a shared object. static unsigned char dyn_plt_entry[plt_entry_size]; // Set the final size. void set_final_data_size() { this->set_data_size((this->count_ + 1) * plt_entry_size); } // Write out the PLT data. void do_write(Output_file*); // The reloc section. Reloc_section* rel_; // The .got.plt section. Output_data_space* got_plt_; // The number of PLT entries. unsigned int count_; }; // Create the PLT section. The ordinary .got section is an argument, // since we need to refer to the start. We also create our own .got // section just for PLT entries. Output_data_plt_i386::Output_data_plt_i386(Layout* layout, Output_data_space* got_plt) : Output_section_data(4), got_plt_(got_plt), count_(0) { this->rel_ = new Reloc_section(); layout->add_output_section_data(".rel.plt", elfcpp::SHT_REL, elfcpp::SHF_ALLOC, this->rel_); } void Output_data_plt_i386::do_adjust_output_section(Output_section* os) { // UnixWare sets the entsize of .plt to 4, and so does the old GNU // linker, and so do we. os->set_entsize(4); } // Add an entry to the PLT. void Output_data_plt_i386::add_entry(Symbol* gsym) { gold_assert(!gsym->has_plt_offset()); // Note that when setting the PLT offset we skip the initial // reserved PLT entry. gsym->set_plt_offset((this->count_ + 1) * plt_entry_size); ++this->count_; section_offset_type got_offset = this->got_plt_->current_data_size(); // Every PLT entry needs a GOT entry which points back to the PLT // entry (this will be changed by the dynamic linker, normally // lazily when the function is called). this->got_plt_->set_current_data_size(got_offset + 4); // Every PLT entry needs a reloc. gsym->set_needs_dynsym_entry(); this->rel_->add_global(gsym, elfcpp::R_386_JUMP_SLOT, this->got_plt_, got_offset); // Note that we don't need to save the symbol. The contents of the // PLT are independent of which symbols are used. The symbols only // appear in the relocations. } // The first entry in the PLT for an executable. unsigned char Output_data_plt_i386::exec_first_plt_entry[plt_entry_size] = { 0xff, 0x35, // pushl contents of memory address 0, 0, 0, 0, // replaced with address of .got + 4 0xff, 0x25, // jmp indirect 0, 0, 0, 0, // replaced with address of .got + 8 0, 0, 0, 0 // unused }; // The first entry in the PLT for a shared object. unsigned char Output_data_plt_i386::dyn_first_plt_entry[plt_entry_size] = { 0xff, 0xb3, 4, 0, 0, 0, // pushl 4(%ebx) 0xff, 0xa3, 8, 0, 0, 0, // jmp *8(%ebx) 0, 0, 0, 0 // unused }; // Subsequent entries in the PLT for an executable. unsigned char Output_data_plt_i386::exec_plt_entry[plt_entry_size] = { 0xff, 0x25, // jmp indirect 0, 0, 0, 0, // replaced with address of symbol in .got 0x68, // pushl immediate 0, 0, 0, 0, // replaced with offset into relocation table 0xe9, // jmp relative 0, 0, 0, 0 // replaced with offset to start of .plt }; // Subsequent entries in the PLT for a shared object. unsigned char Output_data_plt_i386::dyn_plt_entry[plt_entry_size] = { 0xff, 0xa3, // jmp *offset(%ebx) 0, 0, 0, 0, // replaced with offset of symbol in .got 0x68, // pushl immediate 0, 0, 0, 0, // replaced with offset into relocation table 0xe9, // jmp relative 0, 0, 0, 0 // replaced with offset to start of .plt }; // Write out the PLT. This uses the hand-coded instructions above, // and adjusts them as needed. This is all specified by the i386 ELF // Processor Supplement. void Output_data_plt_i386::do_write(Output_file* of) { const off_t offset = this->offset(); const section_size_type oview_size = convert_to_section_size_type(this->data_size()); unsigned char* const oview = of->get_output_view(offset, oview_size); const off_t got_file_offset = this->got_plt_->offset(); const section_size_type got_size = convert_to_section_size_type(this->got_plt_->data_size()); unsigned char* const got_view = of->get_output_view(got_file_offset, got_size); unsigned char* pov = oview; elfcpp::Elf_types<32>::Elf_Addr plt_address = this->address(); elfcpp::Elf_types<32>::Elf_Addr got_address = this->got_plt_->address(); if (parameters->output_is_shared()) memcpy(pov, dyn_first_plt_entry, plt_entry_size); else { memcpy(pov, exec_first_plt_entry, plt_entry_size); elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_address + 4); elfcpp::Swap<32, false>::writeval(pov + 8, got_address + 8); } pov += plt_entry_size; unsigned char* got_pov = got_view; memset(got_pov, 0, 12); got_pov += 12; const int rel_size = elfcpp::Elf_sizes<32>::rel_size; unsigned int plt_offset = plt_entry_size; unsigned int plt_rel_offset = 0; unsigned int got_offset = 12; const unsigned int count = this->count_; for (unsigned int i = 0; i < count; ++i, pov += plt_entry_size, got_pov += 4, plt_offset += plt_entry_size, plt_rel_offset += rel_size, got_offset += 4) { // Set and adjust the PLT entry itself. if (parameters->output_is_shared()) { memcpy(pov, dyn_plt_entry, plt_entry_size); elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_offset); } else { memcpy(pov, exec_plt_entry, plt_entry_size); elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, (got_address + got_offset)); } elfcpp::Swap_unaligned<32, false>::writeval(pov + 7, plt_rel_offset); elfcpp::Swap<32, false>::writeval(pov + 12, - (plt_offset + plt_entry_size)); // Set the entry in the GOT. elfcpp::Swap<32, false>::writeval(got_pov, plt_address + plt_offset + 6); } gold_assert(static_cast(pov - oview) == oview_size); gold_assert(static_cast(got_pov - got_view) == got_size); of->write_output_view(offset, oview_size, oview); of->write_output_view(got_file_offset, got_size, got_view); } // Create a PLT entry for a global symbol. void Target_i386::make_plt_entry(Symbol_table* symtab, Layout* layout, Symbol* gsym) { if (gsym->has_plt_offset()) return; if (this->plt_ == NULL) { // Create the GOT sections first. this->got_section(symtab, layout); this->plt_ = new Output_data_plt_i386(layout, this->got_plt_); layout->add_output_section_data(".plt", elfcpp::SHT_PROGBITS, (elfcpp::SHF_ALLOC | elfcpp::SHF_EXECINSTR), this->plt_); } this->plt_->add_entry(gsym); } // Create a GOT entry for the TLS module index. unsigned int Target_i386::got_mod_index_entry(Symbol_table* symtab, Layout* layout, Sized_relobj<32, false>* object) { if (this->got_mod_index_offset_ == -1U) { gold_assert(symtab != NULL && layout != NULL && object != NULL); Reloc_section* rel_dyn = this->rel_dyn_section(layout); Output_data_got<32, false>* got = this->got_section(symtab, layout); unsigned int got_offset = got->add_constant(0); rel_dyn->add_local(object, 0, elfcpp::R_386_TLS_DTPMOD32, got, got_offset); got->add_constant(0); this->got_mod_index_offset_ = got_offset; } return this->got_mod_index_offset_; } // Handle a relocation against a non-function symbol defined in a // dynamic object. The traditional way to handle this is to generate // a COPY relocation to copy the variable at runtime from the shared // object into the executable's data segment. However, this is // undesirable in general, as if the size of the object changes in the // dynamic object, the executable will no longer work correctly. If // this relocation is in a writable section, then we can create a // dynamic reloc and the dynamic linker will resolve it to the correct // address at runtime. However, we do not want do that if the // relocation is in a read-only section, as it would prevent the // readonly segment from being shared. And if we have to eventually // generate a COPY reloc, then any dynamic relocations will be // useless. So this means that if this is a writable section, we need // to save the relocation until we see whether we have to create a // COPY relocation for this symbol for any other relocation. void Target_i386::copy_reloc(const General_options* options, Symbol_table* symtab, Layout* layout, Sized_relobj<32, false>* object, unsigned int data_shndx, Output_section* output_section, Symbol* gsym, const elfcpp::Rel<32, false>& rel) { Sized_symbol<32>* ssym; ssym = symtab->get_sized_symbol SELECT_SIZE_NAME(32) (gsym SELECT_SIZE(32)); if (!Copy_relocs<32, false>::need_copy_reloc(options, object, data_shndx, ssym)) { // So far we do not need a COPY reloc. Save this relocation. // If it turns out that we never need a COPY reloc for this // symbol, then we will emit the relocation. if (this->copy_relocs_ == NULL) this->copy_relocs_ = new Copy_relocs<32, false>(); this->copy_relocs_->save(ssym, object, data_shndx, output_section, rel); } else { // Allocate space for this symbol in the .bss section. elfcpp::Elf_types<32>::Elf_WXword symsize = ssym->symsize(); // There is no defined way to determine the required alignment // of the symbol. We pick the alignment based on the size. We // set an arbitrary maximum of 256. unsigned int align; for (align = 1; align < 512; align <<= 1) if ((symsize & align) != 0) break; if (this->dynbss_ == NULL) { this->dynbss_ = new Output_data_space(align); layout->add_output_section_data(".bss", elfcpp::SHT_NOBITS, (elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE), this->dynbss_); } Output_data_space* dynbss = this->dynbss_; if (align > dynbss->addralign()) dynbss->set_space_alignment(align); section_size_type dynbss_size = convert_to_section_size_type(dynbss->current_data_size()); dynbss_size = align_address(dynbss_size, align); section_size_type offset = dynbss_size; dynbss->set_current_data_size(dynbss_size + symsize); symtab->define_with_copy_reloc(ssym, dynbss, offset); // Add the COPY reloc. Reloc_section* rel_dyn = this->rel_dyn_section(layout); rel_dyn->add_global(ssym, elfcpp::R_386_COPY, dynbss, offset); } } // Optimize the TLS relocation type based on what we know about the // symbol. IS_FINAL is true if the final address of this symbol is // known at link time. tls::Tls_optimization Target_i386::optimize_tls_reloc(bool is_final, int r_type) { // If we are generating a shared library, then we can't do anything // in the linker. if (parameters->output_is_shared()) return tls::TLSOPT_NONE; switch (r_type) { case elfcpp::R_386_TLS_GD: case elfcpp::R_386_TLS_GOTDESC: case elfcpp::R_386_TLS_DESC_CALL: // These are General-Dynamic which permits fully general TLS // access. Since we know that we are generating an executable, // we can convert this to Initial-Exec. If we also know that // this is a local symbol, we can further switch to Local-Exec. if (is_final) return tls::TLSOPT_TO_LE; return tls::TLSOPT_TO_IE; case elfcpp::R_386_TLS_LDM: // This is Local-Dynamic, which refers to a local symbol in the // dynamic TLS block. Since we know that we generating an // executable, we can switch to Local-Exec. return tls::TLSOPT_TO_LE; case elfcpp::R_386_TLS_LDO_32: // Another type of Local-Dynamic relocation. return tls::TLSOPT_TO_LE; case elfcpp::R_386_TLS_IE: case elfcpp::R_386_TLS_GOTIE: case elfcpp::R_386_TLS_IE_32: // These are Initial-Exec relocs which get the thread offset // from the GOT. If we know that we are linking against the // local symbol, we can switch to Local-Exec, which links the // thread offset into the instruction. if (is_final) return tls::TLSOPT_TO_LE; return tls::TLSOPT_NONE; case elfcpp::R_386_TLS_LE: case elfcpp::R_386_TLS_LE_32: // When we already have Local-Exec, there is nothing further we // can do. return tls::TLSOPT_NONE; default: gold_unreachable(); } } // Report an unsupported relocation against a local symbol. void Target_i386::Scan::unsupported_reloc_local(Sized_relobj<32, false>* object, unsigned int r_type) { gold_error(_("%s: unsupported reloc %u against local symbol"), object->name().c_str(), r_type); } // Scan a relocation for a local symbol. inline void Target_i386::Scan::local(const General_options&, Symbol_table* symtab, Layout* layout, Target_i386* target, Sized_relobj<32, false>* object, unsigned int data_shndx, Output_section* output_section, const elfcpp::Rel<32, false>& reloc, unsigned int r_type, const elfcpp::Sym<32, false>& lsym) { switch (r_type) { case elfcpp::R_386_NONE: case elfcpp::R_386_GNU_VTINHERIT: case elfcpp::R_386_GNU_VTENTRY: break; case elfcpp::R_386_32: // If building a shared library (or a position-independent // executable), we need to create a dynamic relocation for // this location. The relocation applied at link time will // apply the link-time value, so we flag the location with // an R_386_RELATIVE relocation so the dynamic loader can // relocate it easily. if (parameters->output_is_position_independent()) { Reloc_section* rel_dyn = target->rel_dyn_section(layout); unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info()); rel_dyn->add_local_relative(object, r_sym, elfcpp::R_386_RELATIVE, output_section, data_shndx, reloc.get_r_offset()); } break; case elfcpp::R_386_16: case elfcpp::R_386_8: // If building a shared library (or a position-independent // executable), we need to create a dynamic relocation for // this location. Because the addend needs to remain in the // data section, we need to be careful not to apply this // relocation statically. if (parameters->output_is_position_independent()) { Reloc_section* rel_dyn = target->rel_dyn_section(layout); unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info()); rel_dyn->add_local(object, r_sym, r_type, output_section, data_shndx, reloc.get_r_offset()); } break; case elfcpp::R_386_PC32: case elfcpp::R_386_PC16: case elfcpp::R_386_PC8: break; case elfcpp::R_386_PLT32: // Since we know this is a local symbol, we can handle this as a // PC32 reloc. break; case elfcpp::R_386_GOTOFF: case elfcpp::R_386_GOTPC: // We need a GOT section. target->got_section(symtab, layout); break; case elfcpp::R_386_GOT32: { // The symbol requires a GOT entry. Output_data_got<32, false>* got = target->got_section(symtab, layout); unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info()); if (got->add_local(object, r_sym)) { // If we are generating a shared object, we need to add a // dynamic RELATIVE relocation for this symbol's GOT entry. if (parameters->output_is_position_independent()) { Reloc_section* rel_dyn = target->rel_dyn_section(layout); unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info()); rel_dyn->add_local_relative(object, r_sym, elfcpp::R_386_RELATIVE, got, object->local_got_offset(r_sym)); } } } break; // These are relocations which should only be seen by the // dynamic linker, and should never be seen here. case elfcpp::R_386_COPY: case elfcpp::R_386_GLOB_DAT: case elfcpp::R_386_JUMP_SLOT: case elfcpp::R_386_RELATIVE: case elfcpp::R_386_TLS_TPOFF: case elfcpp::R_386_TLS_DTPMOD32: case elfcpp::R_386_TLS_DTPOFF32: case elfcpp::R_386_TLS_TPOFF32: case elfcpp::R_386_TLS_DESC: gold_error(_("%s: unexpected reloc %u in object file"), object->name().c_str(), r_type); break; // These are initial TLS relocs, which are expected when // linking. case elfcpp::R_386_TLS_GD: // Global-dynamic case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url) case elfcpp::R_386_TLS_DESC_CALL: case elfcpp::R_386_TLS_LDM: // Local-dynamic case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic case elfcpp::R_386_TLS_IE: // Initial-exec case elfcpp::R_386_TLS_IE_32: case elfcpp::R_386_TLS_GOTIE: case elfcpp::R_386_TLS_LE: // Local-exec case elfcpp::R_386_TLS_LE_32: { bool output_is_shared = parameters->output_is_shared(); const tls::Tls_optimization optimized_type = Target_i386::optimize_tls_reloc(!output_is_shared, r_type); switch (r_type) { case elfcpp::R_386_TLS_GD: // Global-dynamic if (optimized_type == tls::TLSOPT_NONE) { // Create a pair of GOT entries for the module index and // dtv-relative offset. Output_data_got<32, false>* got = target->got_section(symtab, layout); unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info()); got->add_local_tls_with_rel(object, r_sym, lsym.get_st_shndx(), true, target->rel_dyn_section(layout), elfcpp::R_386_TLS_DTPMOD32); } else if (optimized_type != tls::TLSOPT_TO_LE) unsupported_reloc_local(object, r_type); break; case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva) case elfcpp::R_386_TLS_DESC_CALL: // FIXME: If not relaxing to LE, we need to generate // a GOT entry with an R_386_TLS_DESC reloc. if (optimized_type != tls::TLSOPT_TO_LE) unsupported_reloc_local(object, r_type); break; case elfcpp::R_386_TLS_LDM: // Local-dynamic if (optimized_type == tls::TLSOPT_NONE) { // Create a GOT entry for the module index. target->got_mod_index_entry(symtab, layout, object); } else if (optimized_type != tls::TLSOPT_TO_LE) unsupported_reloc_local(object, r_type); break; case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic break; case elfcpp::R_386_TLS_IE: // Initial-exec case elfcpp::R_386_TLS_IE_32: case elfcpp::R_386_TLS_GOTIE: layout->set_has_static_tls(); if (optimized_type == tls::TLSOPT_NONE) { // For the R_386_TLS_IE relocation, we need to create a // dynamic relocation when building a shared library. if (r_type == elfcpp::R_386_TLS_IE && parameters->output_is_shared()) { Reloc_section* rel_dyn = target->rel_dyn_section(layout); unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info()); rel_dyn->add_local_relative(object, r_sym, elfcpp::R_386_RELATIVE, output_section, data_shndx, reloc.get_r_offset()); } // Create a GOT entry for the tp-relative offset. Output_data_got<32, false>* got = target->got_section(symtab, layout); unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info()); unsigned int dyn_r_type = (r_type == elfcpp::R_386_TLS_IE_32 ? elfcpp::R_386_TLS_TPOFF32 : elfcpp::R_386_TLS_TPOFF); got->add_local_with_rel(object, r_sym, target->rel_dyn_section(layout), dyn_r_type); } else if (optimized_type != tls::TLSOPT_TO_LE) unsupported_reloc_local(object, r_type); break; case elfcpp::R_386_TLS_LE: // Local-exec case elfcpp::R_386_TLS_LE_32: layout->set_has_static_tls(); if (output_is_shared) { // We need to create a dynamic relocation. unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info()); unsigned int dyn_r_type = (r_type == elfcpp::R_386_TLS_LE_32 ? elfcpp::R_386_TLS_TPOFF32 : elfcpp::R_386_TLS_TPOFF); Reloc_section* rel_dyn = target->rel_dyn_section(layout); rel_dyn->add_local(object, r_sym, dyn_r_type, output_section, data_shndx, reloc.get_r_offset()); } break; default: gold_unreachable(); } } break; case elfcpp::R_386_32PLT: case elfcpp::R_386_TLS_GD_32: case elfcpp::R_386_TLS_GD_PUSH: case elfcpp::R_386_TLS_GD_CALL: case elfcpp::R_386_TLS_GD_POP: case elfcpp::R_386_TLS_LDM_32: case elfcpp::R_386_TLS_LDM_PUSH: case elfcpp::R_386_TLS_LDM_CALL: case elfcpp::R_386_TLS_LDM_POP: case elfcpp::R_386_USED_BY_INTEL_200: default: unsupported_reloc_local(object, r_type); break; } } // Report an unsupported relocation against a global symbol. void Target_i386::Scan::unsupported_reloc_global(Sized_relobj<32, false>* object, unsigned int r_type, Symbol* gsym) { gold_error(_("%s: unsupported reloc %u against global symbol %s"), object->name().c_str(), r_type, gsym->demangled_name().c_str()); } // Scan a relocation for a global symbol. inline void Target_i386::Scan::global(const General_options& options, Symbol_table* symtab, Layout* layout, Target_i386* target, Sized_relobj<32, false>* object, unsigned int data_shndx, Output_section* output_section, const elfcpp::Rel<32, false>& reloc, unsigned int r_type, Symbol* gsym) { switch (r_type) { case elfcpp::R_386_NONE: case elfcpp::R_386_GNU_VTINHERIT: case elfcpp::R_386_GNU_VTENTRY: break; case elfcpp::R_386_32: case elfcpp::R_386_16: case elfcpp::R_386_8: { // Make a PLT entry if necessary. if (gsym->needs_plt_entry()) { target->make_plt_entry(symtab, layout, gsym); // Since this is not a PC-relative relocation, we may be // taking the address of a function. In that case we need to // set the entry in the dynamic symbol table to the address of // the PLT entry. if (gsym->is_from_dynobj() && !parameters->output_is_shared()) gsym->set_needs_dynsym_value(); } // Make a dynamic relocation if necessary. if (gsym->needs_dynamic_reloc(Symbol::ABSOLUTE_REF)) { if (target->may_need_copy_reloc(gsym)) { target->copy_reloc(&options, symtab, layout, object, data_shndx, output_section, gsym, reloc); } else if (r_type == elfcpp::R_386_32 && gsym->can_use_relative_reloc(false)) { Reloc_section* rel_dyn = target->rel_dyn_section(layout); rel_dyn->add_global_relative(gsym, elfcpp::R_386_RELATIVE, output_section, object, data_shndx, reloc.get_r_offset()); } else { Reloc_section* rel_dyn = target->rel_dyn_section(layout); rel_dyn->add_global(gsym, r_type, output_section, object, data_shndx, reloc.get_r_offset()); } } } break; case elfcpp::R_386_PC32: case elfcpp::R_386_PC16: case elfcpp::R_386_PC8: { // Make a PLT entry if necessary. if (gsym->needs_plt_entry()) { // These relocations are used for function calls only in // non-PIC code. For a 32-bit relocation in a shared library, // we'll need a text relocation anyway, so we can skip the // PLT entry and let the dynamic linker bind the call directly // to the target. For smaller relocations, we should use a // PLT entry to ensure that the call can reach. if (!parameters->output_is_shared() || r_type != elfcpp::R_386_PC32) target->make_plt_entry(symtab, layout, gsym); } // Make a dynamic relocation if necessary. int flags = Symbol::NON_PIC_REF; if (gsym->type() == elfcpp::STT_FUNC) flags |= Symbol::FUNCTION_CALL; if (gsym->needs_dynamic_reloc(flags)) { if (target->may_need_copy_reloc(gsym)) { target->copy_reloc(&options, symtab, layout, object, data_shndx, output_section, gsym, reloc); } else { Reloc_section* rel_dyn = target->rel_dyn_section(layout); rel_dyn->add_global(gsym, r_type, output_section, object, data_shndx, reloc.get_r_offset()); } } } break; case elfcpp::R_386_GOT32: { // The symbol requires a GOT entry. Output_data_got<32, false>* got = target->got_section(symtab, layout); if (gsym->final_value_is_known()) got->add_global(gsym); else { // If this symbol is not fully resolved, we need to add a // GOT entry with a dynamic relocation. Reloc_section* rel_dyn = target->rel_dyn_section(layout); if (gsym->is_from_dynobj() || gsym->is_preemptible()) got->add_global_with_rel(gsym, rel_dyn, elfcpp::R_386_GLOB_DAT); else { if (got->add_global(gsym)) rel_dyn->add_global_relative(gsym, elfcpp::R_386_RELATIVE, got, gsym->got_offset()); } } } break; case elfcpp::R_386_PLT32: // If the symbol is fully resolved, this is just a PC32 reloc. // Otherwise we need a PLT entry. if (gsym->final_value_is_known()) break; // If building a shared library, we can also skip the PLT entry // if the symbol is defined in the output file and is protected // or hidden. if (gsym->is_defined() && !gsym->is_from_dynobj() && !gsym->is_preemptible()) break; target->make_plt_entry(symtab, layout, gsym); break; case elfcpp::R_386_GOTOFF: case elfcpp::R_386_GOTPC: // We need a GOT section. target->got_section(symtab, layout); break; // These are relocations which should only be seen by the // dynamic linker, and should never be seen here. case elfcpp::R_386_COPY: case elfcpp::R_386_GLOB_DAT: case elfcpp::R_386_JUMP_SLOT: case elfcpp::R_386_RELATIVE: case elfcpp::R_386_TLS_TPOFF: case elfcpp::R_386_TLS_DTPMOD32: case elfcpp::R_386_TLS_DTPOFF32: case elfcpp::R_386_TLS_TPOFF32: case elfcpp::R_386_TLS_DESC: gold_error(_("%s: unexpected reloc %u in object file"), object->name().c_str(), r_type); break; // These are initial tls relocs, which are expected when // linking. case elfcpp::R_386_TLS_GD: // Global-dynamic case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url) case elfcpp::R_386_TLS_DESC_CALL: case elfcpp::R_386_TLS_LDM: // Local-dynamic case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic case elfcpp::R_386_TLS_IE: // Initial-exec case elfcpp::R_386_TLS_IE_32: case elfcpp::R_386_TLS_GOTIE: case elfcpp::R_386_TLS_LE: // Local-exec case elfcpp::R_386_TLS_LE_32: { const bool is_final = gsym->final_value_is_known(); const tls::Tls_optimization optimized_type = Target_i386::optimize_tls_reloc(is_final, r_type); switch (r_type) { case elfcpp::R_386_TLS_GD: // Global-dynamic if (optimized_type == tls::TLSOPT_NONE) { // Create a pair of GOT entries for the module index and // dtv-relative offset. Output_data_got<32, false>* got = target->got_section(symtab, layout); got->add_global_tls_with_rel(gsym, target->rel_dyn_section(layout), elfcpp::R_386_TLS_DTPMOD32, elfcpp::R_386_TLS_DTPOFF32); } else if (optimized_type == tls::TLSOPT_TO_IE) { // Create a GOT entry for the tp-relative offset. Output_data_got<32, false>* got = target->got_section(symtab, layout); got->add_global_with_rel(gsym, target->rel_dyn_section(layout), elfcpp::R_386_TLS_TPOFF32); } else if (optimized_type != tls::TLSOPT_TO_LE) unsupported_reloc_global(object, r_type, gsym); break; case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (~oliva url) case elfcpp::R_386_TLS_DESC_CALL: // FIXME: If not relaxing to LE, we need to generate // a GOT entry with an R_386_TLS_DESC reloc. if (optimized_type != tls::TLSOPT_TO_LE) unsupported_reloc_global(object, r_type, gsym); unsupported_reloc_global(object, r_type, gsym); break; case elfcpp::R_386_TLS_LDM: // Local-dynamic if (optimized_type == tls::TLSOPT_NONE) { // Create a GOT entry for the module index. target->got_mod_index_entry(symtab, layout, object); } else if (optimized_type != tls::TLSOPT_TO_LE) unsupported_reloc_global(object, r_type, gsym); break; case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic break; case elfcpp::R_386_TLS_IE: // Initial-exec case elfcpp::R_386_TLS_IE_32: case elfcpp::R_386_TLS_GOTIE: layout->set_has_static_tls(); if (optimized_type == tls::TLSOPT_NONE) { // For the R_386_TLS_IE relocation, we need to create a // dynamic relocation when building a shared library. if (r_type == elfcpp::R_386_TLS_IE && parameters->output_is_shared()) { Reloc_section* rel_dyn = target->rel_dyn_section(layout); rel_dyn->add_global_relative(gsym, elfcpp::R_386_RELATIVE, output_section, object, data_shndx, reloc.get_r_offset()); } // Create a GOT entry for the tp-relative offset. Output_data_got<32, false>* got = target->got_section(symtab, layout); unsigned int dyn_r_type = (r_type == elfcpp::R_386_TLS_IE_32 ? elfcpp::R_386_TLS_TPOFF32 : elfcpp::R_386_TLS_TPOFF); got->add_global_with_rel(gsym, target->rel_dyn_section(layout), dyn_r_type); } else if (optimized_type != tls::TLSOPT_TO_LE) unsupported_reloc_global(object, r_type, gsym); break; case elfcpp::R_386_TLS_LE: // Local-exec case elfcpp::R_386_TLS_LE_32: layout->set_has_static_tls(); if (parameters->output_is_shared()) { // We need to create a dynamic relocation. unsigned int dyn_r_type = (r_type == elfcpp::R_386_TLS_LE_32 ? elfcpp::R_386_TLS_TPOFF32 : elfcpp::R_386_TLS_TPOFF); Reloc_section* rel_dyn = target->rel_dyn_section(layout); rel_dyn->add_global(gsym, dyn_r_type, output_section, object, data_shndx, reloc.get_r_offset()); } break; default: gold_unreachable(); } } break; case elfcpp::R_386_32PLT: case elfcpp::R_386_TLS_GD_32: case elfcpp::R_386_TLS_GD_PUSH: case elfcpp::R_386_TLS_GD_CALL: case elfcpp::R_386_TLS_GD_POP: case elfcpp::R_386_TLS_LDM_32: case elfcpp::R_386_TLS_LDM_PUSH: case elfcpp::R_386_TLS_LDM_CALL: case elfcpp::R_386_TLS_LDM_POP: case elfcpp::R_386_USED_BY_INTEL_200: default: unsupported_reloc_global(object, r_type, gsym); break; } } // Scan relocations for a section. void Target_i386::scan_relocs(const General_options& options, Symbol_table* symtab, Layout* layout, Sized_relobj<32, false>* object, unsigned int data_shndx, unsigned int sh_type, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, bool needs_special_offset_handling, size_t local_symbol_count, const unsigned char* plocal_symbols) { if (sh_type == elfcpp::SHT_RELA) { gold_error(_("%s: unsupported RELA reloc section"), object->name().c_str()); return; } gold::scan_relocs<32, false, Target_i386, elfcpp::SHT_REL, Target_i386::Scan>( options, symtab, layout, this, object, data_shndx, prelocs, reloc_count, output_section, needs_special_offset_handling, local_symbol_count, plocal_symbols); } // Finalize the sections. void Target_i386::do_finalize_sections(Layout* layout) { // Fill in some more dynamic tags. Output_data_dynamic* const odyn = layout->dynamic_data(); if (odyn != NULL) { if (this->got_plt_ != NULL) odyn->add_section_address(elfcpp::DT_PLTGOT, this->got_plt_); if (this->plt_ != NULL) { const Output_data* od = this->plt_->rel_plt(); odyn->add_section_size(elfcpp::DT_PLTRELSZ, od); odyn->add_section_address(elfcpp::DT_JMPREL, od); odyn->add_constant(elfcpp::DT_PLTREL, elfcpp::DT_REL); } if (this->rel_dyn_ != NULL) { const Output_data* od = this->rel_dyn_; odyn->add_section_address(elfcpp::DT_REL, od); odyn->add_section_size(elfcpp::DT_RELSZ, od); odyn->add_constant(elfcpp::DT_RELENT, elfcpp::Elf_sizes<32>::rel_size); } if (!parameters->output_is_shared()) { // The value of the DT_DEBUG tag is filled in by the dynamic // linker at run time, and used by the debugger. odyn->add_constant(elfcpp::DT_DEBUG, 0); } } // Emit any relocs we saved in an attempt to avoid generating COPY // relocs. if (this->copy_relocs_ == NULL) return; if (this->copy_relocs_->any_to_emit()) { Reloc_section* rel_dyn = this->rel_dyn_section(layout); this->copy_relocs_->emit(rel_dyn); } delete this->copy_relocs_; this->copy_relocs_ = NULL; } // Return whether a direct absolute static relocation needs to be applied. // In cases where Scan::local() or Scan::global() has created // a dynamic relocation other than R_386_RELATIVE, the addend // of the relocation is carried in the data, and we must not // apply the static relocation. inline bool Target_i386::Relocate::should_apply_static_reloc(const Sized_symbol<32>* gsym, int ref_flags, bool is_32bit) { // For local symbols, we will have created a non-RELATIVE dynamic // relocation only if (a) the output is position independent, // (b) the relocation is absolute (not pc- or segment-relative), and // (c) the relocation is not 32 bits wide. if (gsym == NULL) return !(parameters->output_is_position_independent() && (ref_flags & Symbol::ABSOLUTE_REF) && !is_32bit); // For global symbols, we use the same helper routines used in the // scan pass. If we did not create a dynamic relocation, or if we // created a RELATIVE dynamic relocation, we should apply the static // relocation. bool has_dyn = gsym->needs_dynamic_reloc(ref_flags); bool is_rel = (ref_flags & Symbol::ABSOLUTE_REF) && gsym->can_use_relative_reloc(ref_flags & Symbol::FUNCTION_CALL); return !has_dyn || is_rel; } // Perform a relocation. inline bool Target_i386::Relocate::relocate(const Relocate_info<32, false>* relinfo, Target_i386* target, size_t relnum, const elfcpp::Rel<32, false>& rel, unsigned int r_type, const Sized_symbol<32>* gsym, const Symbol_value<32>* psymval, unsigned char* view, elfcpp::Elf_types<32>::Elf_Addr address, section_size_type view_size) { if (this->skip_call_tls_get_addr_) { if (r_type != elfcpp::R_386_PLT32 || gsym == NULL || strcmp(gsym->name(), "___tls_get_addr") != 0) gold_error_at_location(relinfo, relnum, rel.get_r_offset(), _("missing expected TLS relocation")); else { this->skip_call_tls_get_addr_ = false; return false; } } // Pick the value to use for symbols defined in shared objects. Symbol_value<32> symval; bool is_nonpic = (r_type == elfcpp::R_386_PC8 || r_type == elfcpp::R_386_PC16 || r_type == elfcpp::R_386_PC32); if (gsym != NULL && (gsym->is_from_dynobj() || (parameters->output_is_shared() && gsym->is_preemptible())) && gsym->has_plt_offset() && (!is_nonpic || !parameters->output_is_shared())) { symval.set_output_value(target->plt_section()->address() + gsym->plt_offset()); psymval = &symval; } const Sized_relobj<32, false>* object = relinfo->object; // Get the GOT offset if needed. // The GOT pointer points to the end of the GOT section. // We need to subtract the size of the GOT section to get // the actual offset to use in the relocation. bool have_got_offset = false; unsigned int got_offset = 0; switch (r_type) { case elfcpp::R_386_GOT32: if (gsym != NULL) { gold_assert(gsym->has_got_offset()); got_offset = gsym->got_offset() - target->got_size(); } else { unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info()); gold_assert(object->local_has_got_offset(r_sym)); got_offset = object->local_got_offset(r_sym) - target->got_size(); } have_got_offset = true; break; default: break; } switch (r_type) { case elfcpp::R_386_NONE: case elfcpp::R_386_GNU_VTINHERIT: case elfcpp::R_386_GNU_VTENTRY: break; case elfcpp::R_386_32: if (should_apply_static_reloc(gsym, Symbol::ABSOLUTE_REF, true)) Relocate_functions<32, false>::rel32(view, object, psymval); break; case elfcpp::R_386_PC32: { int ref_flags = Symbol::NON_PIC_REF; if (gsym != NULL && gsym->type() == elfcpp::STT_FUNC) ref_flags |= Symbol::FUNCTION_CALL; if (should_apply_static_reloc(gsym, ref_flags, true)) Relocate_functions<32, false>::pcrel32(view, object, psymval, address); } break; case elfcpp::R_386_16: if (should_apply_static_reloc(gsym, Symbol::ABSOLUTE_REF, false)) Relocate_functions<32, false>::rel16(view, object, psymval); break; case elfcpp::R_386_PC16: { int ref_flags = Symbol::NON_PIC_REF; if (gsym != NULL && gsym->type() == elfcpp::STT_FUNC) ref_flags |= Symbol::FUNCTION_CALL; if (should_apply_static_reloc(gsym, ref_flags, false)) Relocate_functions<32, false>::pcrel32(view, object, psymval, address); } break; case elfcpp::R_386_8: if (should_apply_static_reloc(gsym, Symbol::ABSOLUTE_REF, false)) Relocate_functions<32, false>::rel8(view, object, psymval); break; case elfcpp::R_386_PC8: { int ref_flags = Symbol::NON_PIC_REF; if (gsym != NULL && gsym->type() == elfcpp::STT_FUNC) ref_flags |= Symbol::FUNCTION_CALL; if (should_apply_static_reloc(gsym, ref_flags, false)) Relocate_functions<32, false>::pcrel32(view, object, psymval, address); } break; case elfcpp::R_386_PLT32: gold_assert(gsym == NULL || gsym->has_plt_offset() || gsym->final_value_is_known() || (gsym->is_defined() && !gsym->is_from_dynobj() && !gsym->is_preemptible())); Relocate_functions<32, false>::pcrel32(view, object, psymval, address); break; case elfcpp::R_386_GOT32: gold_assert(have_got_offset); Relocate_functions<32, false>::rel32(view, got_offset); break; case elfcpp::R_386_GOTOFF: { elfcpp::Elf_types<32>::Elf_Addr value; value = (psymval->value(object, 0) - target->got_plt_section()->address()); Relocate_functions<32, false>::rel32(view, value); } break; case elfcpp::R_386_GOTPC: { elfcpp::Elf_types<32>::Elf_Addr value; value = target->got_plt_section()->address(); Relocate_functions<32, false>::pcrel32(view, value, address); } break; case elfcpp::R_386_COPY: case elfcpp::R_386_GLOB_DAT: case elfcpp::R_386_JUMP_SLOT: case elfcpp::R_386_RELATIVE: // These are outstanding tls relocs, which are unexpected when // linking. case elfcpp::R_386_TLS_TPOFF: case elfcpp::R_386_TLS_DTPMOD32: case elfcpp::R_386_TLS_DTPOFF32: case elfcpp::R_386_TLS_TPOFF32: case elfcpp::R_386_TLS_DESC: gold_error_at_location(relinfo, relnum, rel.get_r_offset(), _("unexpected reloc %u in object file"), r_type); break; // These are initial tls relocs, which are expected when // linking. case elfcpp::R_386_TLS_GD: // Global-dynamic case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url) case elfcpp::R_386_TLS_DESC_CALL: case elfcpp::R_386_TLS_LDM: // Local-dynamic case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic case elfcpp::R_386_TLS_IE: // Initial-exec case elfcpp::R_386_TLS_IE_32: case elfcpp::R_386_TLS_GOTIE: case elfcpp::R_386_TLS_LE: // Local-exec case elfcpp::R_386_TLS_LE_32: this->relocate_tls(relinfo, target, relnum, rel, r_type, gsym, psymval, view, address, view_size); break; case elfcpp::R_386_32PLT: case elfcpp::R_386_TLS_GD_32: case elfcpp::R_386_TLS_GD_PUSH: case elfcpp::R_386_TLS_GD_CALL: case elfcpp::R_386_TLS_GD_POP: case elfcpp::R_386_TLS_LDM_32: case elfcpp::R_386_TLS_LDM_PUSH: case elfcpp::R_386_TLS_LDM_CALL: case elfcpp::R_386_TLS_LDM_POP: case elfcpp::R_386_USED_BY_INTEL_200: default: gold_error_at_location(relinfo, relnum, rel.get_r_offset(), _("unsupported reloc %u"), r_type); break; } return true; } // Perform a TLS relocation. inline void Target_i386::Relocate::relocate_tls(const Relocate_info<32, false>* relinfo, Target_i386* target, size_t relnum, const elfcpp::Rel<32, false>& rel, unsigned int r_type, const Sized_symbol<32>* gsym, const Symbol_value<32>* psymval, unsigned char* view, elfcpp::Elf_types<32>::Elf_Addr, section_size_type view_size) { Output_segment* tls_segment = relinfo->layout->tls_segment(); const Sized_relobj<32, false>* object = relinfo->object; elfcpp::Elf_types<32>::Elf_Addr value = psymval->value(object, 0); const bool is_final = (gsym == NULL ? !parameters->output_is_position_independent() : gsym->final_value_is_known()); const tls::Tls_optimization optimized_type = Target_i386::optimize_tls_reloc(is_final, r_type); switch (r_type) { case elfcpp::R_386_TLS_GD: // Global-dynamic if (optimized_type == tls::TLSOPT_TO_LE) { gold_assert(tls_segment != NULL); this->tls_gd_to_le(relinfo, relnum, tls_segment, rel, r_type, value, view, view_size); break; } else { unsigned int got_offset; if (gsym != NULL) { gold_assert(gsym->has_tls_got_offset(true)); got_offset = gsym->tls_got_offset(true) - target->got_size(); } else { unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info()); gold_assert(object->local_has_tls_got_offset(r_sym, true)); got_offset = (object->local_tls_got_offset(r_sym, true) - target->got_size()); } if (optimized_type == tls::TLSOPT_TO_IE) { gold_assert(tls_segment != NULL); this->tls_gd_to_ie(relinfo, relnum, tls_segment, rel, r_type, got_offset, view, view_size); break; } else if (optimized_type == tls::TLSOPT_NONE) { // Relocate the field with the offset of the pair of GOT // entries. Relocate_functions<32, false>::rel32(view, got_offset); break; } } gold_error_at_location(relinfo, relnum, rel.get_r_offset(), _("unsupported reloc %u"), r_type); break; case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url) case elfcpp::R_386_TLS_DESC_CALL: gold_error_at_location(relinfo, relnum, rel.get_r_offset(), _("unsupported reloc %u"), r_type); break; case elfcpp::R_386_TLS_LDM: // Local-dynamic if (this->local_dynamic_type_ == LOCAL_DYNAMIC_SUN) { gold_error_at_location(relinfo, relnum, rel.get_r_offset(), _("both SUN and GNU model " "TLS relocations")); break; } this->local_dynamic_type_ = LOCAL_DYNAMIC_GNU; if (optimized_type == tls::TLSOPT_TO_LE) { gold_assert(tls_segment != NULL); this->tls_ld_to_le(relinfo, relnum, tls_segment, rel, r_type, value, view, view_size); break; } else if (optimized_type == tls::TLSOPT_NONE) { // Relocate the field with the offset of the GOT entry for // the module index. unsigned int got_offset; got_offset = (target->got_mod_index_entry(NULL, NULL, NULL) - target->got_size()); Relocate_functions<32, false>::rel32(view, got_offset); break; } gold_error_at_location(relinfo, relnum, rel.get_r_offset(), _("unsupported reloc %u"), r_type); break; case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic // This reloc can appear in debugging sections, in which case we // won't see the TLS_LDM reloc. The local_dynamic_type field // tells us this. if (optimized_type == tls::TLSOPT_TO_LE) { gold_assert(tls_segment != NULL); value -= tls_segment->memsz(); } Relocate_functions<32, false>::rel32(view, value); break; case elfcpp::R_386_TLS_IE: // Initial-exec case elfcpp::R_386_TLS_GOTIE: case elfcpp::R_386_TLS_IE_32: if (optimized_type == tls::TLSOPT_TO_LE) { gold_assert(tls_segment != NULL); Target_i386::Relocate::tls_ie_to_le(relinfo, relnum, tls_segment, rel, r_type, value, view, view_size); break; } else if (optimized_type == tls::TLSOPT_NONE) { // Relocate the field with the offset of the GOT entry for // the tp-relative offset of the symbol. unsigned int got_offset; if (gsym != NULL) { gold_assert(gsym->has_got_offset()); got_offset = gsym->got_offset(); } else { unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info()); gold_assert(object->local_has_got_offset(r_sym)); got_offset = object->local_got_offset(r_sym); } // For the R_386_TLS_IE relocation, we need to apply the // absolute address of the GOT entry. if (r_type == elfcpp::R_386_TLS_IE) got_offset += target->got_plt_section()->address(); // All GOT offsets are relative to the end of the GOT. got_offset -= target->got_size(); Relocate_functions<32, false>::rel32(view, got_offset); break; } gold_error_at_location(relinfo, relnum, rel.get_r_offset(), _("unsupported reloc %u"), r_type); break; case elfcpp::R_386_TLS_LE: // Local-exec // If we're creating a shared library, a dynamic relocation will // have been created for this location, so do not apply it now. if (!parameters->output_is_shared()) { gold_assert(tls_segment != NULL); value -= tls_segment->memsz(); Relocate_functions<32, false>::rel32(view, value); } break; case elfcpp::R_386_TLS_LE_32: // If we're creating a shared library, a dynamic relocation will // have been created for this location, so do not apply it now. if (!parameters->output_is_shared()) { gold_assert(tls_segment != NULL); value = tls_segment->memsz() - value; Relocate_functions<32, false>::rel32(view, value); } break; } } // Do a relocation in which we convert a TLS General-Dynamic to a // Local-Exec. inline void Target_i386::Relocate::tls_gd_to_le(const Relocate_info<32, false>* relinfo, size_t relnum, Output_segment* tls_segment, const elfcpp::Rel<32, false>& rel, unsigned int, elfcpp::Elf_types<32>::Elf_Addr value, unsigned char* view, section_size_type view_size) { // leal foo(,%reg,1),%eax; call ___tls_get_addr // ==> movl %gs:0,%eax; subl $foo@tpoff,%eax // leal foo(%reg),%eax; call ___tls_get_addr // ==> movl %gs:0,%eax; subl $foo@tpoff,%eax tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2); tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9); unsigned char op1 = view[-1]; unsigned char op2 = view[-2]; tls::check_tls(relinfo, relnum, rel.get_r_offset(), op2 == 0x8d || op2 == 0x04); tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8); int roff = 5; if (op2 == 0x04) { tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -3); tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[-3] == 0x8d); tls::check_tls(relinfo, relnum, rel.get_r_offset(), ((op1 & 0xc7) == 0x05 && op1 != (4 << 3))); memcpy(view - 3, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12); } else { tls::check_tls(relinfo, relnum, rel.get_r_offset(), (op1 & 0xf8) == 0x80 && (op1 & 7) != 4); if (rel.get_r_offset() + 9 < view_size && view[9] == 0x90) { // There is a trailing nop. Use the size byte subl. memcpy(view - 2, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12); roff = 6; } else { // Use the five byte subl. memcpy(view - 2, "\x65\xa1\0\0\0\0\x2d\0\0\0", 11); } } value = tls_segment->memsz() - value; Relocate_functions<32, false>::rel32(view + roff, value); // The next reloc should be a PLT32 reloc against __tls_get_addr. // We can skip it. this->skip_call_tls_get_addr_ = true; } // Do a relocation in which we convert a TLS General-Dynamic to an // Initial-Exec. inline void Target_i386::Relocate::tls_gd_to_ie(const Relocate_info<32, false>* relinfo, size_t relnum, Output_segment* tls_segment, const elfcpp::Rel<32, false>& rel, unsigned int, elfcpp::Elf_types<32>::Elf_Addr value, unsigned char* view, section_size_type view_size) { // leal foo(,%ebx,1),%eax; call ___tls_get_addr // ==> movl %gs:0,%eax; addl foo@gotntpoff(%ebx),%eax tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2); tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9); unsigned char op1 = view[-1]; unsigned char op2 = view[-2]; tls::check_tls(relinfo, relnum, rel.get_r_offset(), op2 == 0x8d || op2 == 0x04); tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8); int roff = 5; // FIXME: For now, support only one form. tls::check_tls(relinfo, relnum, rel.get_r_offset(), op1 == 0x8d && op2 == 0x04); if (op2 == 0x04) { tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -3); tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[-3] == 0x8d); tls::check_tls(relinfo, relnum, rel.get_r_offset(), ((op1 & 0xc7) == 0x05 && op1 != (4 << 3))); memcpy(view - 3, "\x65\xa1\0\0\0\0\x03\x83\0\0\0", 12); } else { tls::check_tls(relinfo, relnum, rel.get_r_offset(), (op1 & 0xf8) == 0x80 && (op1 & 7) != 4); if (rel.get_r_offset() + 9 < view_size && view[9] == 0x90) { // FIXME: This is not the right instruction sequence. // There is a trailing nop. Use the size byte subl. memcpy(view - 2, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12); roff = 6; } else { // FIXME: This is not the right instruction sequence. // Use the five byte subl. memcpy(view - 2, "\x65\xa1\0\0\0\0\x2d\0\0\0", 11); } } value = tls_segment->memsz() - value; Relocate_functions<32, false>::rel32(view + roff, value); // The next reloc should be a PLT32 reloc against __tls_get_addr. // We can skip it. this->skip_call_tls_get_addr_ = true; } // Do a relocation in which we convert a TLS Local-Dynamic to a // Local-Exec. inline void Target_i386::Relocate::tls_ld_to_le(const Relocate_info<32, false>* relinfo, size_t relnum, Output_segment*, const elfcpp::Rel<32, false>& rel, unsigned int, elfcpp::Elf_types<32>::Elf_Addr, unsigned char* view, section_size_type view_size) { // leal foo(%reg), %eax; call ___tls_get_addr // ==> movl %gs:0,%eax; nop; leal 0(%esi,1),%esi tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2); tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9); // FIXME: Does this test really always pass? tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[-2] == 0x8d && view[-1] == 0x83); tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8); memcpy(view - 2, "\x65\xa1\0\0\0\0\x90\x8d\x74\x26\0", 11); // The next reloc should be a PLT32 reloc against __tls_get_addr. // We can skip it. this->skip_call_tls_get_addr_ = true; } // Do a relocation in which we convert a TLS Initial-Exec to a // Local-Exec. inline void Target_i386::Relocate::tls_ie_to_le(const Relocate_info<32, false>* relinfo, size_t relnum, Output_segment* tls_segment, const elfcpp::Rel<32, false>& rel, unsigned int r_type, elfcpp::Elf_types<32>::Elf_Addr value, unsigned char* view, section_size_type view_size) { // We have to actually change the instructions, which means that we // need to examine the opcodes to figure out which instruction we // are looking at. if (r_type == elfcpp::R_386_TLS_IE) { // movl %gs:XX,%eax ==> movl $YY,%eax // movl %gs:XX,%reg ==> movl $YY,%reg // addl %gs:XX,%reg ==> addl $YY,%reg tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -1); tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4); unsigned char op1 = view[-1]; if (op1 == 0xa1) { // movl XX,%eax ==> movl $YY,%eax view[-1] = 0xb8; } else { tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2); unsigned char op2 = view[-2]; if (op2 == 0x8b) { // movl XX,%reg ==> movl $YY,%reg tls::check_tls(relinfo, relnum, rel.get_r_offset(), (op1 & 0xc7) == 0x05); view[-2] = 0xc7; view[-1] = 0xc0 | ((op1 >> 3) & 7); } else if (op2 == 0x03) { // addl XX,%reg ==> addl $YY,%reg tls::check_tls(relinfo, relnum, rel.get_r_offset(), (op1 & 0xc7) == 0x05); view[-2] = 0x81; view[-1] = 0xc0 | ((op1 >> 3) & 7); } else tls::check_tls(relinfo, relnum, rel.get_r_offset(), 0); } } else { // subl %gs:XX(%reg1),%reg2 ==> subl $YY,%reg2 // movl %gs:XX(%reg1),%reg2 ==> movl $YY,%reg2 // addl %gs:XX(%reg1),%reg2 ==> addl $YY,$reg2 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2); tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4); unsigned char op1 = view[-1]; unsigned char op2 = view[-2]; tls::check_tls(relinfo, relnum, rel.get_r_offset(), (op1 & 0xc0) == 0x80 && (op1 & 7) != 4); if (op2 == 0x8b) { // movl %gs:XX(%reg1),%reg2 ==> movl $YY,%reg2 view[-2] = 0xc7; view[-1] = 0xc0 | ((op1 >> 3) & 7); } else if (op2 == 0x2b) { // subl %gs:XX(%reg1),%reg2 ==> subl $YY,%reg2 view[-2] = 0x81; view[-1] = 0xe8 | ((op1 >> 3) & 7); } else if (op2 == 0x03) { // addl %gs:XX(%reg1),%reg2 ==> addl $YY,$reg2 view[-2] = 0x81; view[-1] = 0xc0 | ((op1 >> 3) & 7); } else tls::check_tls(relinfo, relnum, rel.get_r_offset(), 0); } value = tls_segment->memsz() - value; if (r_type == elfcpp::R_386_TLS_IE || r_type == elfcpp::R_386_TLS_GOTIE) value = - value; Relocate_functions<32, false>::rel32(view, value); } // Relocate section data. void Target_i386::relocate_section(const Relocate_info<32, false>* relinfo, unsigned int sh_type, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, bool needs_special_offset_handling, unsigned char* view, elfcpp::Elf_types<32>::Elf_Addr address, section_size_type view_size) { gold_assert(sh_type == elfcpp::SHT_REL); gold::relocate_section<32, false, Target_i386, elfcpp::SHT_REL, Target_i386::Relocate>( relinfo, this, prelocs, reloc_count, output_section, needs_special_offset_handling, view, address, view_size); } // Return the value to use for a dynamic which requires special // treatment. This is how we support equality comparisons of function // pointers across shared library boundaries, as described in the // processor specific ABI supplement. uint64_t Target_i386::do_dynsym_value(const Symbol* gsym) const { gold_assert(gsym->is_from_dynobj() && gsym->has_plt_offset()); return this->plt_section()->address() + gsym->plt_offset(); } // Return a string used to fill a code section with nops to take up // the specified length. std::string Target_i386::do_code_fill(section_size_type length) { if (length >= 16) { // Build a jmp instruction to skip over the bytes. unsigned char jmp[5]; jmp[0] = 0xe9; elfcpp::Swap_unaligned<32, false>::writeval(jmp + 1, length - 5); return (std::string(reinterpret_cast(&jmp[0]), 5) + std::string(length - 5, '\0')); } // Nop sequences of various lengths. const char nop1[1] = { 0x90 }; // nop const char nop2[2] = { 0x66, 0x90 }; // xchg %ax %ax const char nop3[3] = { 0x8d, 0x76, 0x00 }; // leal 0(%esi),%esi const char nop4[4] = { 0x8d, 0x74, 0x26, 0x00}; // leal 0(%esi,1),%esi const char nop5[5] = { 0x90, 0x8d, 0x74, 0x26, // nop 0x00 }; // leal 0(%esi,1),%esi const char nop6[6] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi 0x00, 0x00 }; const char nop7[7] = { 0x8d, 0xb4, 0x26, 0x00, // leal 0L(%esi,1),%esi 0x00, 0x00, 0x00 }; const char nop8[8] = { 0x90, 0x8d, 0xb4, 0x26, // nop 0x00, 0x00, 0x00, 0x00 }; // leal 0L(%esi,1),%esi const char nop9[9] = { 0x89, 0xf6, 0x8d, 0xbc, // movl %esi,%esi 0x27, 0x00, 0x00, 0x00, // leal 0L(%edi,1),%edi 0x00 }; const char nop10[10] = { 0x8d, 0x76, 0x00, 0x8d, // leal 0(%esi),%esi 0xbc, 0x27, 0x00, 0x00, // leal 0L(%edi,1),%edi 0x00, 0x00 }; const char nop11[11] = { 0x8d, 0x74, 0x26, 0x00, // leal 0(%esi,1),%esi 0x8d, 0xbc, 0x27, 0x00, // leal 0L(%edi,1),%edi 0x00, 0x00, 0x00 }; const char nop12[12] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi 0x00, 0x00, 0x8d, 0xbf, // leal 0L(%edi),%edi 0x00, 0x00, 0x00, 0x00 }; const char nop13[13] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi 0x00, 0x00, 0x8d, 0xbc, // leal 0L(%edi,1),%edi 0x27, 0x00, 0x00, 0x00, 0x00 }; const char nop14[14] = { 0x8d, 0xb4, 0x26, 0x00, // leal 0L(%esi,1),%esi 0x00, 0x00, 0x00, 0x8d, // leal 0L(%edi,1),%edi 0xbc, 0x27, 0x00, 0x00, 0x00, 0x00 }; const char nop15[15] = { 0xeb, 0x0d, 0x90, 0x90, // jmp .+15 0x90, 0x90, 0x90, 0x90, // nop,nop,nop,... 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90 }; const char* nops[16] = { NULL, nop1, nop2, nop3, nop4, nop5, nop6, nop7, nop8, nop9, nop10, nop11, nop12, nop13, nop14, nop15 }; return std::string(nops[length], length); } // The selector for i386 object files. class Target_selector_i386 : public Target_selector { public: Target_selector_i386() : Target_selector(elfcpp::EM_386, 32, false) { } Target* recognize(int machine, int osabi, int abiversion); private: Target_i386* target_; }; // Recognize an i386 object file when we already know that the machine // number is EM_386. Target* Target_selector_i386::recognize(int, int, int) { if (this->target_ == NULL) this->target_ = new Target_i386(); return this->target_; } Target_selector_i386 target_selector_i386; } // End anonymous namespace.