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// i386.cc -- i386 target support for gold. // Copyright 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc. // Written by Ian Lance Taylor <iant@google.com>. // 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 <cstring> #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 "copy-relocs.h" #include "target.h" #include "target-reloc.h" #include "target-select.h" #include "tls.h" #include "freebsd.h" #include "gc.h" namespace { using namespace gold; // A class to handle the PLT data. class Output_data_plt_i386 : public Output_section_data { public: typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, false> Reloc_section; Output_data_plt_i386(Symbol_table*, Layout*, Output_data_space*); // Add an entry to the PLT. void add_entry(Symbol* gsym); // Add an entry to the PLT for a local STT_GNU_IFUNC symbol. unsigned int add_local_ifunc_entry(Sized_relobj_file<32, false>* relobj, unsigned int local_sym_index); // Return the .rel.plt section data. Reloc_section* rel_plt() const { return this->rel_; } // Return where the TLS_DESC relocations should go. Reloc_section* rel_tls_desc(Layout*); // Return the number of PLT entries. unsigned int entry_count() const { return this->count_; } // Return the offset of the first non-reserved PLT entry. static unsigned int first_plt_entry_offset() { return plt_entry_size; } // Return the size of a PLT entry. static unsigned int get_plt_entry_size() { return plt_entry_size; } protected: void do_adjust_output_section(Output_section* os); // Write to a map file. void do_print_to_mapfile(Mapfile* mapfile) const { mapfile->print_output_data(this, _("** PLT")); } 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*); // We keep a list of global STT_GNU_IFUNC symbols, each with its // offset in the GOT. struct Global_ifunc { Symbol* sym; unsigned int got_offset; }; // We keep a list of local STT_GNU_IFUNC symbols, each with its // offset in the GOT. struct Local_ifunc { Sized_relobj_file<32, false>* object; unsigned int local_sym_index; unsigned int got_offset; }; // The reloc section. Reloc_section* rel_; // The TLS_DESC relocations, if necessary. These must follow the // regular PLT relocs. Reloc_section* tls_desc_rel_; // The .got.plt section. Output_data_space* got_plt_; // The number of PLT entries. unsigned int count_; // Global STT_GNU_IFUNC symbols. std::vector<Global_ifunc> global_ifuncs_; // Local STT_GNU_IFUNC symbols. std::vector<Local_ifunc> local_ifuncs_; }; // 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 Target_freebsd<32, false> { public: typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, false> Reloc_section; Target_i386() : Target_freebsd<32, false>(&i386_info), got_(NULL), plt_(NULL), got_plt_(NULL), got_tlsdesc_(NULL), global_offset_table_(NULL), rel_dyn_(NULL), copy_relocs_(elfcpp::R_386_COPY), dynbss_(NULL), got_mod_index_offset_(-1U), tls_base_symbol_defined_(false) { } inline bool can_check_for_function_pointers() const { return true; } virtual bool can_icf_inline_merge_sections () const { return true; } // Process the relocations to determine unreferenced sections for // garbage collection. void gc_process_relocs(Symbol_table* symtab, Layout* layout, Sized_relobj_file<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); // Scan the relocations to look for symbol adjustments. void scan_relocs(Symbol_table* symtab, Layout* layout, Sized_relobj_file<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*, const Input_objects*, Symbol_table*); // 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, const Reloc_symbol_changes*); // Scan the relocs during a relocatable link. void scan_relocatable_relocs(Symbol_table* symtab, Layout* layout, Sized_relobj_file<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, Relocatable_relocs*); // Relocate a section during a relocatable link. void relocate_for_relocatable(const Relocate_info<32, false>*, unsigned int sh_type, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, off_t offset_in_output_section, const Relocatable_relocs*, unsigned char* view, elfcpp::Elf_types<32>::Elf_Addr view_address, section_size_type view_size, unsigned char* reloc_view, section_size_type reloc_view_size); // Return a string used to fill a code section with nops. std::string do_code_fill(section_size_type length) const; // Return whether SYM is defined by the ABI. bool do_is_defined_by_abi(const Symbol* sym) const { return strcmp(sym->name(), "___tls_get_addr") == 0; } // Return whether a symbol name implies a local label. The UnixWare // 2.1 cc generates temporary symbols that start with .X, so we // recognize them here. FIXME: do other SVR4 compilers also use .X?. // If so, we should move the .X recognition into // Target::do_is_local_label_name. bool do_is_local_label_name(const char* name) const { if (name[0] == '.' && name[1] == 'X') return true; return Target::do_is_local_label_name(name); } // Return the PLT section. Output_data* do_plt_section_for_global(const Symbol*) const { return this->plt_section(); } Output_data* do_plt_section_for_local(const Relobj*, unsigned int) const { return this->plt_section(); } // Return whether SYM is call to a non-split function. bool do_is_call_to_non_split(const Symbol* sym, unsigned int) const; // Adjust -fsplit-stack code which calls non-split-stack code. void do_calls_non_split(Relobj* object, unsigned int shndx, section_offset_type fnoffset, section_size_type fnsize, unsigned char* view, section_size_type view_size, std::string* from, std::string* to) const; // Return the size of the GOT section. section_size_type got_size() const { gold_assert(this->got_ != NULL); return this->got_->data_size(); } // Return the number of entries in the GOT. unsigned int got_entry_count() const { if (this->got_ == NULL) return 0; return this->got_size() / 4; } // Return the number of entries in the PLT. unsigned int plt_entry_count() const; // Return the offset of the first non-reserved PLT entry. unsigned int first_plt_entry_offset() const; // Return the size of each PLT entry. unsigned int plt_entry_size() const; private: // The class which scans relocations. struct Scan { static inline int get_reference_flags(unsigned int r_type); inline void local(Symbol_table* symtab, Layout* layout, Target_i386* target, Sized_relobj_file<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(Symbol_table* symtab, Layout* layout, Target_i386* target, Sized_relobj_file<32, false>* object, unsigned int data_shndx, Output_section* output_section, const elfcpp::Rel<32, false>& reloc, unsigned int r_type, Symbol* gsym); inline bool local_reloc_may_be_function_pointer(Symbol_table* symtab, Layout* layout, Target_i386* target, Sized_relobj_file<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 bool global_reloc_may_be_function_pointer(Symbol_table* symtab, Layout* layout, Target_i386* target, Sized_relobj_file<32, false>* object, unsigned int data_shndx, Output_section* output_section, const elfcpp::Rel<32, false>& reloc, unsigned int r_type, Symbol* gsym); inline bool possible_function_pointer_reloc(unsigned int r_type); bool reloc_needs_plt_for_ifunc(Sized_relobj_file<32, false>*, unsigned int r_type); static void unsupported_reloc_local(Sized_relobj_file<32, false>*, unsigned int r_type); static void unsupported_reloc_global(Sized_relobj_file<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, unsigned int r_type, bool is_32bit, Output_section* output_section); // 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*, Output_section*, 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_GOTDESC or TLS_DESC_CALL General-Dynamic to Initial-Exec // transition. inline void tls_desc_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_GOTDESC or TLS_DESC_CALL General-Dynamic to Local-Exec // transition. inline void tls_desc_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_; }; // A class which returns the size required for a relocation type, // used while scanning relocs during a relocatable link. class Relocatable_size_for_reloc { public: unsigned int get_size_for_reloc(unsigned int, Relobj*); }; // 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_; } // Get the GOT section for TLSDESC entries. Output_data_got<32, false>* got_tlsdesc_section() const { gold_assert(this->got_tlsdesc_ != NULL); return this->got_tlsdesc_; } // Create the PLT section. void make_plt_section(Symbol_table* symtab, Layout* layout); // Create a PLT entry for a global symbol. void make_plt_entry(Symbol_table*, Layout*, Symbol*); // Create a PLT entry for a local STT_GNU_IFUNC symbol. void make_local_ifunc_plt_entry(Symbol_table*, Layout*, Sized_relobj_file<32, false>* relobj, unsigned int local_sym_index); // Define the _TLS_MODULE_BASE_ symbol in the TLS segment. void define_tls_base_symbol(Symbol_table*, Layout*); // Create a GOT entry for the TLS module index. unsigned int got_mod_index_entry(Symbol_table* symtab, Layout* layout, Sized_relobj_file<32, false>* object); // Get the PLT section. 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*); // Get the section to use for TLS_DESC relocations. Reloc_section* rel_tls_desc_section(Layout*) const; // Add a potential copy relocation. void copy_reloc(Symbol_table* symtab, Layout* layout, Sized_relobj_file<32, false>* object, unsigned int shndx, Output_section* output_section, Symbol* sym, const elfcpp::Rel<32, false>& reloc) { this->copy_relocs_.copy_reloc(symtab, layout, symtab->get_sized_symbol<32>(sym), object, shndx, output_section, reloc, this->rel_dyn_section(layout)); } // Information about this specific target which we pass to the // general Target structure. static const Target::Target_info i386_info; // The types of GOT entries needed for this platform. // These values are exposed to the ABI in an incremental link. // Do not renumber existing values without changing the version // number of the .gnu_incremental_inputs section. enum Got_type { GOT_TYPE_STANDARD = 0, // GOT entry for a regular symbol GOT_TYPE_TLS_NOFFSET = 1, // GOT entry for negative TLS offset GOT_TYPE_TLS_OFFSET = 2, // GOT entry for positive TLS offset GOT_TYPE_TLS_PAIR = 3, // GOT entry for TLS module/offset pair GOT_TYPE_TLS_DESC = 4 // GOT entry for TLS_DESC pair }; // 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 GOT section for TLSDESC relocations. Output_data_got<32, false>* got_tlsdesc_; // The _GLOBAL_OFFSET_TABLE_ symbol. Symbol* global_offset_table_; // The dynamic reloc section. Reloc_section* rel_dyn_; // Relocs saved to avoid a COPY reloc. Copy_relocs<elfcpp::SHT_REL, 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_; // True if the _TLS_MODULE_BASE_ symbol has been defined. bool tls_base_symbol_defined_; }; 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 '\0', // wrap_char "/usr/lib/libc.so.1", // dynamic_linker 0x08048000, // default_text_segment_address 0x1000, // abi_pagesize (overridable by -z max-page-size) 0x1000, // common_pagesize (overridable by -z common-page-size) elfcpp::SHN_UNDEF, // small_common_shndx elfcpp::SHN_UNDEF, // large_common_shndx 0, // small_common_section_flags 0, // large_common_section_flags NULL, // attributes_section NULL // attributes_vendor }; // 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_, ORDER_RELRO_LAST, true); this->got_plt_ = new Output_data_space(4, "** GOT PLT"); layout->add_output_section_data(".got.plt", elfcpp::SHT_PROGBITS, (elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE), this->got_plt_, ORDER_NON_RELRO_FIRST, false); // The first three entries are reserved. this->got_plt_->set_current_data_size(3 * 4); // Those bytes can go into the relro segment. layout->increase_relro(3 * 4); // Define _GLOBAL_OFFSET_TABLE_ at the start of the PLT. this->global_offset_table_ = symtab->define_in_output_data("_GLOBAL_OFFSET_TABLE_", NULL, Symbol_table::PREDEFINED, this->got_plt_, 0, 0, elfcpp::STT_OBJECT, elfcpp::STB_LOCAL, elfcpp::STV_HIDDEN, 0, false, false); // If there are any TLSDESC relocations, they get GOT entries in // .got.plt after the jump slot entries. this->got_tlsdesc_ = new Output_data_got<32, false>(); layout->add_output_section_data(".got.plt", elfcpp::SHT_PROGBITS, (elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE), this->got_tlsdesc_, ORDER_NON_RELRO_FIRST, 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(parameters->options().combreloc()); layout->add_output_section_data(".rel.dyn", elfcpp::SHT_REL, elfcpp::SHF_ALLOC, this->rel_dyn_, ORDER_DYNAMIC_RELOCS, false); } return this->rel_dyn_; } // 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(Symbol_table* symtab, Layout* layout, Output_data_space* got_plt) : Output_section_data(4), tls_desc_rel_(NULL), got_plt_(got_plt), count_(0), global_ifuncs_(), local_ifuncs_() { this->rel_ = new Reloc_section(false); layout->add_output_section_data(".rel.plt", elfcpp::SHT_REL, elfcpp::SHF_ALLOC, this->rel_, ORDER_DYNAMIC_PLT_RELOCS, false); if (parameters->doing_static_link()) { // A statically linked executable will only have a .rel.plt // section to hold R_386_IRELATIVE relocs for STT_GNU_IFUNC // symbols. The library will use these symbols to locate the // IRELATIVE relocs at program startup time. symtab->define_in_output_data("__rel_iplt_start", NULL, Symbol_table::PREDEFINED, this->rel_, 0, 0, elfcpp::STT_NOTYPE, elfcpp::STB_GLOBAL, elfcpp::STV_HIDDEN, 0, false, true); symtab->define_in_output_data("__rel_iplt_end", NULL, Symbol_table::PREDEFINED, this->rel_, 0, 0, elfcpp::STT_NOTYPE, elfcpp::STB_GLOBAL, elfcpp::STV_HIDDEN, 0, true, true); } } 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. if (gsym->type() == elfcpp::STT_GNU_IFUNC && gsym->can_use_relative_reloc(false)) { this->rel_->add_symbolless_global_addend(gsym, elfcpp::R_386_IRELATIVE, this->got_plt_, got_offset); struct Global_ifunc gi; gi.sym = gsym; gi.got_offset = got_offset; this->global_ifuncs_.push_back(gi); } else { 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. } // Add an entry to the PLT for a local STT_GNU_IFUNC symbol. Return // the PLT offset. unsigned int Output_data_plt_i386::add_local_ifunc_entry( Sized_relobj_file<32, false>* relobj, unsigned int local_sym_index) { unsigned int 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->got_plt_->set_current_data_size(got_offset + 4); // Every PLT entry needs a reloc. this->rel_->add_symbolless_local_addend(relobj, local_sym_index, elfcpp::R_386_IRELATIVE, this->got_plt_, got_offset); struct Local_ifunc li; li.object = relobj; li.local_sym_index = local_sym_index; li.got_offset = got_offset; this->local_ifuncs_.push_back(li); return plt_offset; } // Return where the TLS_DESC relocations should go, creating it if // necessary. These follow the JUMP_SLOT relocations. Output_data_plt_i386::Reloc_section* Output_data_plt_i386::rel_tls_desc(Layout* layout) { if (this->tls_desc_rel_ == NULL) { this->tls_desc_rel_ = new Reloc_section(false); layout->add_output_section_data(".rel.plt", elfcpp::SHT_REL, elfcpp::SHF_ALLOC, this->tls_desc_rel_, ORDER_DYNAMIC_PLT_RELOCS, false); gold_assert(this->tls_desc_rel_->output_section() == this->rel_->output_section()); } return this->tls_desc_rel_; } // 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->options().output_is_position_independent()) 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->options().output_is_position_independent()) { 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); } // If any STT_GNU_IFUNC symbols have PLT entries, we need to change // the GOT to point to the actual symbol value, rather than point to // the PLT entry. That will let the dynamic linker call the right // function when resolving IRELATIVE relocations. for (std::vector<Global_ifunc>::const_iterator p = this->global_ifuncs_.begin(); p != this->global_ifuncs_.end(); ++p) { const Sized_symbol<32>* ssym = static_cast<const Sized_symbol<32>*>(p->sym); elfcpp::Swap<32, false>::writeval(got_view + p->got_offset, ssym->value()); } for (std::vector<Local_ifunc>::const_iterator p = this->local_ifuncs_.begin(); p != this->local_ifuncs_.end(); ++p) { const Symbol_value<32>* psymval = p->object->local_symbol(p->local_sym_index); elfcpp::Swap<32, false>::writeval(got_view + p->got_offset, psymval->value(p->object, 0)); } gold_assert(static_cast<section_size_type>(pov - oview) == oview_size); gold_assert(static_cast<section_size_type>(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 the PLT section. void Target_i386::make_plt_section(Symbol_table* symtab, Layout* layout) { if (this->plt_ == NULL) { // Create the GOT sections first. this->got_section(symtab, layout); this->plt_ = new Output_data_plt_i386(symtab, layout, this->got_plt_); layout->add_output_section_data(".plt", elfcpp::SHT_PROGBITS, (elfcpp::SHF_ALLOC | elfcpp::SHF_EXECINSTR), this->plt_, ORDER_PLT, false); // Make the sh_info field of .rel.plt point to .plt. Output_section* rel_plt_os = this->plt_->rel_plt()->output_section(); rel_plt_os->set_info_section(this->plt_->output_section()); } } // 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) this->make_plt_section(symtab, layout); this->plt_->add_entry(gsym); } // Make a PLT entry for a local STT_GNU_IFUNC symbol. void Target_i386::make_local_ifunc_plt_entry(Symbol_table* symtab, Layout* layout, Sized_relobj_file<32, false>* relobj, unsigned int local_sym_index) { if (relobj->local_has_plt_offset(local_sym_index)) return; if (this->plt_ == NULL) this->make_plt_section(symtab, layout); unsigned int plt_offset = this->plt_->add_local_ifunc_entry(relobj, local_sym_index); relobj->set_local_plt_offset(local_sym_index, plt_offset); } // Return the number of entries in the PLT. unsigned int Target_i386::plt_entry_count() const { if (this->plt_ == NULL) return 0; return this->plt_->entry_count(); } // Return the offset of the first non-reserved PLT entry. unsigned int Target_i386::first_plt_entry_offset() const { return Output_data_plt_i386::first_plt_entry_offset(); } // Return the size of each PLT entry. unsigned int Target_i386::plt_entry_size() const { return Output_data_plt_i386::get_plt_entry_size(); } // Get the section to use for TLS_DESC relocations. Target_i386::Reloc_section* Target_i386::rel_tls_desc_section(Layout* layout) const { return this->plt_section()->rel_tls_desc(layout); } // Define the _TLS_MODULE_BASE_ symbol in the TLS segment. void Target_i386::define_tls_base_symbol(Symbol_table* symtab, Layout* layout) { if (this->tls_base_symbol_defined_) return; Output_segment* tls_segment = layout->tls_segment(); if (tls_segment != NULL) { bool is_exec = parameters->options().output_is_executable(); symtab->define_in_output_segment("_TLS_MODULE_BASE_", NULL, Symbol_table::PREDEFINED, tls_segment, 0, 0, elfcpp::STT_TLS, elfcpp::STB_LOCAL, elfcpp::STV_HIDDEN, 0, (is_exec ? Symbol::SEGMENT_END : Symbol::SEGMENT_START), true); } this->tls_base_symbol_defined_ = true; } // Create a GOT entry for the TLS module index. unsigned int Target_i386::got_mod_index_entry(Symbol_table* symtab, Layout* layout, Sized_relobj_file<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_; } // 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->options().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(); } } // Get the Reference_flags for a particular relocation. int Target_i386::Scan::get_reference_flags(unsigned int r_type) { switch (r_type) { case elfcpp::R_386_NONE: case elfcpp::R_386_GNU_VTINHERIT: case elfcpp::R_386_GNU_VTENTRY: case elfcpp::R_386_GOTPC: // No symbol reference. return 0; case elfcpp::R_386_32: case elfcpp::R_386_16: case elfcpp::R_386_8: return Symbol::ABSOLUTE_REF; case elfcpp::R_386_PC32: case elfcpp::R_386_PC16: case elfcpp::R_386_PC8: case elfcpp::R_386_GOTOFF: return Symbol::RELATIVE_REF; case elfcpp::R_386_PLT32: return Symbol::FUNCTION_CALL | Symbol::RELATIVE_REF; case elfcpp::R_386_GOT32: // Absolute in GOT. return Symbol::ABSOLUTE_REF; 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: return Symbol::TLS_REF; 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_IRELATIVE: 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: 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: // Not expected. We will give an error later. return 0; } } // Report an unsupported relocation against a local symbol. void Target_i386::Scan::unsupported_reloc_local(Sized_relobj_file<32, false>* object, unsigned int r_type) { gold_error(_("%s: unsupported reloc %u against local symbol"), object->name().c_str(), r_type); } // Return whether we need to make a PLT entry for a relocation of a // given type against a STT_GNU_IFUNC symbol. bool Target_i386::Scan::reloc_needs_plt_for_ifunc( Sized_relobj_file<32, false>* object, unsigned int r_type) { int flags = Scan::get_reference_flags(r_type); if (flags & Symbol::TLS_REF) gold_error(_("%s: unsupported TLS reloc %u for IFUNC symbol"), object->name().c_str(), r_type); return flags != 0; } // Scan a relocation for a local symbol. inline void Target_i386::Scan::local(Symbol_table* symtab, Layout* layout, Target_i386* target, Sized_relobj_file<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) { // A local STT_GNU_IFUNC symbol may require a PLT entry. if (lsym.get_st_type() == elfcpp::STT_GNU_IFUNC && this->reloc_needs_plt_for_ifunc(object, r_type)) { unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info()); target->make_local_ifunc_plt_entry(symtab, layout, object, r_sym); } 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->options().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->options().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()); if (lsym.get_st_type() != elfcpp::STT_SECTION) rel_dyn->add_local(object, r_sym, r_type, output_section, data_shndx, reloc.get_r_offset()); else { gold_assert(lsym.get_st_value() == 0); unsigned int shndx = lsym.get_st_shndx(); bool is_ordinary; shndx = object->adjust_sym_shndx(r_sym, shndx, &is_ordinary); if (!is_ordinary) object->error(_("section symbol %u has bad shndx %u"), r_sym, shndx); else rel_dyn->add_local_section(object, shndx, 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()); // For a STT_GNU_IFUNC symbol we want the PLT offset. That // lets function pointers compare correctly with shared // libraries. Otherwise we would need an IRELATIVE reloc. bool is_new; if (lsym.get_st_type() == elfcpp::STT_GNU_IFUNC) is_new = got->add_local_plt(object, r_sym, GOT_TYPE_STANDARD); else is_new = got->add_local(object, r_sym, GOT_TYPE_STANDARD); if (is_new) { // If we are generating a shared object, we need to add a // dynamic RELATIVE relocation for this symbol's GOT entry. if (parameters->options().output_is_position_independent()) { Reloc_section* rel_dyn = target->rel_dyn_section(layout); unsigned int got_offset = object->local_got_offset(r_sym, GOT_TYPE_STANDARD); rel_dyn->add_local_relative(object, r_sym, elfcpp::R_386_RELATIVE, got, got_offset); } } } 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_IRELATIVE: 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->options().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()); unsigned int shndx = lsym.get_st_shndx(); bool is_ordinary; shndx = object->adjust_sym_shndx(r_sym, shndx, &is_ordinary); if (!is_ordinary) object->error(_("local symbol %u has bad shndx %u"), r_sym, shndx); else got->add_local_pair_with_rel(object, r_sym, shndx, GOT_TYPE_TLS_PAIR, target->rel_dyn_section(layout), elfcpp::R_386_TLS_DTPMOD32, 0); } 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) target->define_tls_base_symbol(symtab, layout); if (optimized_type == tls::TLSOPT_NONE) { // Create a double GOT entry with an R_386_TLS_DESC // reloc. The R_386_TLS_DESC reloc is resolved // lazily, so the GOT entry needs to be in an area in // .got.plt, not .got. Call got_section to make sure // the section has been created. target->got_section(symtab, layout); Output_data_got<32, false>* got = target->got_tlsdesc_section(); unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info()); if (!object->local_has_got_offset(r_sym, GOT_TYPE_TLS_DESC)) { unsigned int got_offset = got->add_constant(0); // The local symbol value is stored in the second // GOT entry. got->add_local(object, r_sym, GOT_TYPE_TLS_DESC); // That set the GOT offset of the local symbol to // point to the second entry, but we want it to // point to the first. object->set_local_got_offset(r_sym, GOT_TYPE_TLS_DESC, got_offset); Reloc_section* rt = target->rel_tls_desc_section(layout); rt->add_absolute(elfcpp::R_386_TLS_DESC, got, got_offset); } } else if (optimized_type != tls::TLSOPT_TO_LE) unsupported_reloc_local(object, r_type); break; case elfcpp::R_386_TLS_DESC_CALL: 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->options().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); unsigned int got_type = (r_type == elfcpp::R_386_TLS_IE_32 ? GOT_TYPE_TLS_OFFSET : GOT_TYPE_TLS_NOFFSET); got->add_local_with_rel(object, r_sym, got_type, 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. gold_assert(lsym.get_st_type() != elfcpp::STT_SECTION); 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_file<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()); } inline bool Target_i386::Scan::possible_function_pointer_reloc(unsigned int r_type) { switch (r_type) { case elfcpp::R_386_32: case elfcpp::R_386_16: case elfcpp::R_386_8: case elfcpp::R_386_GOTOFF: case elfcpp::R_386_GOT32: { return true; } default: return false; } return false; } inline bool Target_i386::Scan::local_reloc_may_be_function_pointer( Symbol_table* , Layout* , Target_i386* , Sized_relobj_file<32, false>* , unsigned int , Output_section* , const elfcpp::Rel<32, false>& , unsigned int r_type, const elfcpp::Sym<32, false>&) { return possible_function_pointer_reloc(r_type); } inline bool Target_i386::Scan::global_reloc_may_be_function_pointer( Symbol_table* , Layout* , Target_i386* , Sized_relobj_file<32, false>* , unsigned int , Output_section* , const elfcpp::Rel<32, false>& , unsigned int r_type, Symbol*) { return possible_function_pointer_reloc(r_type); } // Scan a relocation for a global symbol. inline void Target_i386::Scan::global(Symbol_table* symtab, Layout* layout, Target_i386* target, Sized_relobj_file<32, false>* object, unsigned int data_shndx, Output_section* output_section, const elfcpp::Rel<32, false>& reloc, unsigned int r_type, Symbol* gsym) { // A STT_GNU_IFUNC symbol may require a PLT entry. if (gsym->type() == elfcpp::STT_GNU_IFUNC && this->reloc_needs_plt_for_ifunc(object, r_type)) target->make_plt_entry(symtab, layout, 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->options().shared()) gsym->set_needs_dynsym_value(); } // Make a dynamic relocation if necessary. if (gsym->needs_dynamic_reloc(Scan::get_reference_flags(r_type))) { if (gsym->may_need_copy_reloc()) { target->copy_reloc(symtab, layout, object, data_shndx, output_section, gsym, reloc); } else if (r_type == elfcpp::R_386_32 && gsym->type() == elfcpp::STT_GNU_IFUNC && gsym->can_use_relative_reloc(false) && !gsym->is_from_dynobj() && !gsym->is_undefined() && !gsym->is_preemptible()) { // Use an IRELATIVE reloc for a locally defined // STT_GNU_IFUNC symbol. This makes a function // address in a PIE executable match the address in a // shared library that it links against. Reloc_section* rel_dyn = target->rel_dyn_section(layout); rel_dyn->add_symbolless_global_addend(gsym, elfcpp::R_386_IRELATIVE, output_section, object, data_shndx, reloc.get_r_offset()); } 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->options().shared() || r_type != elfcpp::R_386_PC32) target->make_plt_entry(symtab, layout, gsym); } // Make a dynamic relocation if necessary. if (gsym->needs_dynamic_reloc(Scan::get_reference_flags(r_type))) { if (gsym->may_need_copy_reloc()) { target->copy_reloc(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()) { // For a STT_GNU_IFUNC symbol we want the PLT address. if (gsym->type() == elfcpp::STT_GNU_IFUNC) got->add_global_plt(gsym, GOT_TYPE_STANDARD); else got->add_global(gsym, GOT_TYPE_STANDARD); } 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_undefined() || gsym->is_preemptible() || (gsym->type() == elfcpp::STT_GNU_IFUNC && parameters->options().output_is_position_independent())) got->add_global_with_rel(gsym, GOT_TYPE_STANDARD, rel_dyn, elfcpp::R_386_GLOB_DAT); else { // For a STT_GNU_IFUNC symbol we want to write the PLT // offset into the GOT, so that function pointer // comparisons work correctly. bool is_new; if (gsym->type() != elfcpp::STT_GNU_IFUNC) is_new = got->add_global(gsym, GOT_TYPE_STANDARD); else { is_new = got->add_global_plt(gsym, GOT_TYPE_STANDARD); // Tell the dynamic linker to use the PLT address // when resolving relocations. if (gsym->is_from_dynobj() && !parameters->options().shared()) gsym->set_needs_dynsym_value(); } if (is_new) { unsigned int got_off = gsym->got_offset(GOT_TYPE_STANDARD); rel_dyn->add_global_relative(gsym, elfcpp::R_386_RELATIVE, got, got_off); } } } } 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_IRELATIVE: 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_pair_with_rel(gsym, GOT_TYPE_TLS_PAIR, 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, GOT_TYPE_TLS_NOFFSET, target->rel_dyn_section(layout), elfcpp::R_386_TLS_TPOFF); } 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) target->define_tls_base_symbol(symtab, layout); if (optimized_type == tls::TLSOPT_NONE) { // Create a double GOT entry with an R_386_TLS_DESC // reloc. The R_386_TLS_DESC reloc is resolved // lazily, so the GOT entry needs to be in an area in // .got.plt, not .got. Call got_section to make sure // the section has been created. target->got_section(symtab, layout); Output_data_got<32, false>* got = target->got_tlsdesc_section(); Reloc_section* rt = target->rel_tls_desc_section(layout); got->add_global_pair_with_rel(gsym, GOT_TYPE_TLS_DESC, rt, elfcpp::R_386_TLS_DESC, 0); } 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, GOT_TYPE_TLS_NOFFSET, target->rel_dyn_section(layout), elfcpp::R_386_TLS_TPOFF); } else if (optimized_type != tls::TLSOPT_TO_LE) unsupported_reloc_global(object, r_type, gsym); break; case elfcpp::R_386_TLS_DESC_CALL: 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->options().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); unsigned int got_type = (r_type == elfcpp::R_386_TLS_IE_32 ? GOT_TYPE_TLS_OFFSET : GOT_TYPE_TLS_NOFFSET); got->add_global_with_rel(gsym, got_type, 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->options().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; } } // Process relocations for gc. void Target_i386::gc_process_relocs(Symbol_table* symtab, Layout* layout, Sized_relobj_file<32, false>* object, unsigned int data_shndx, unsigned int, 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) { gold::gc_process_relocs<32, false, Target_i386, elfcpp::SHT_REL, Target_i386::Scan, Target_i386::Relocatable_size_for_reloc>( symtab, layout, this, object, data_shndx, prelocs, reloc_count, output_section, needs_special_offset_handling, local_symbol_count, plocal_symbols); } // Scan relocations for a section. void Target_i386::scan_relocs(Symbol_table* symtab, Layout* layout, Sized_relobj_file<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>( 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, const Input_objects*, Symbol_table* symtab) { const Reloc_section* rel_plt = (this->plt_ == NULL ? NULL : this->plt_->rel_plt()); layout->add_target_dynamic_tags(true, this->got_plt_, rel_plt, this->rel_dyn_, true, false); // Emit any relocs we saved in an attempt to avoid generating COPY // relocs. if (this->copy_relocs_.any_saved_relocs()) this->copy_relocs_.emit(this->rel_dyn_section(layout)); // Set the size of the _GLOBAL_OFFSET_TABLE_ symbol to the size of // the .got.plt section. Symbol* sym = this->global_offset_table_; if (sym != NULL) { uint32_t data_size = this->got_plt_->current_data_size(); symtab->get_sized_symbol<32>(sym)->set_symsize(data_size); } } // 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, unsigned int r_type, bool is_32bit, Output_section* output_section) { // If the output section is not allocated, then we didn't call // scan_relocs, we didn't create a dynamic reloc, and we must apply // the reloc here. if ((output_section->flags() & elfcpp::SHF_ALLOC) == 0) return true; int ref_flags = Scan::get_reference_flags(r_type); // 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->options().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, Output_section* output_section, 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 && r_type != elfcpp::R_386_PC32) || 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; } } const Sized_relobj_file<32, false>* object = relinfo->object; // Pick the value to use for symbols defined in shared objects. Symbol_value<32> symval; if (gsym != NULL && gsym->type() == elfcpp::STT_GNU_IFUNC && r_type == elfcpp::R_386_32 && gsym->needs_dynamic_reloc(Scan::get_reference_flags(r_type)) && gsym->can_use_relative_reloc(false) && !gsym->is_from_dynobj() && !gsym->is_undefined() && !gsym->is_preemptible()) { // In this case we are generating a R_386_IRELATIVE reloc. We // want to use the real value of the symbol, not the PLT offset. } else if (gsym != NULL && gsym->use_plt_offset(Scan::get_reference_flags(r_type))) { symval.set_output_value(target->plt_section()->address() + gsym->plt_offset()); psymval = &symval; } else if (gsym == NULL && psymval->is_ifunc_symbol()) { unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info()); if (object->local_has_plt_offset(r_sym)) { symval.set_output_value(target->plt_section()->address() + object->local_plt_offset(r_sym)); psymval = &symval; } } // 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_TYPE_STANDARD)); got_offset = (gsym->got_offset(GOT_TYPE_STANDARD) - 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_TYPE_STANDARD)); got_offset = (object->local_got_offset(r_sym, GOT_TYPE_STANDARD) - 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, r_type, true, output_section)) Relocate_functions<32, false>::rel32(view, object, psymval); break; case elfcpp::R_386_PC32: if (should_apply_static_reloc(gsym, r_type, true, output_section)) Relocate_functions<32, false>::pcrel32(view, object, psymval, address); break; case elfcpp::R_386_16: if (should_apply_static_reloc(gsym, r_type, false, output_section)) Relocate_functions<32, false>::rel16(view, object, psymval); break; case elfcpp::R_386_PC16: if (should_apply_static_reloc(gsym, r_type, false, output_section)) Relocate_functions<32, false>::pcrel16(view, object, psymval, address); break; case elfcpp::R_386_8: if (should_apply_static_reloc(gsym, r_type, false, output_section)) Relocate_functions<32, false>::rel8(view, object, psymval); break; case elfcpp::R_386_PC8: if (should_apply_static_reloc(gsym, r_type, false, output_section)) Relocate_functions<32, false>::pcrel8(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: case elfcpp::R_386_IRELATIVE: // 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_file<32, false>* object = relinfo->object; elfcpp::Elf_types<32>::Elf_Addr value = psymval->value(object, 0); const bool is_final = (gsym == NULL ? !parameters->options().shared() : 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_type = (optimized_type == tls::TLSOPT_TO_IE ? GOT_TYPE_TLS_NOFFSET : GOT_TYPE_TLS_PAIR); unsigned int got_offset; if (gsym != NULL) { gold_assert(gsym->has_got_offset(got_type)); got_offset = gsym->got_offset(got_type) - 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_type)); got_offset = (object->local_got_offset(r_sym, got_type) - 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: this->local_dynamic_type_ = LOCAL_DYNAMIC_GNU; if (optimized_type == tls::TLSOPT_TO_LE) { gold_assert(tls_segment != NULL); this->tls_desc_gd_to_le(relinfo, relnum, tls_segment, rel, r_type, value, view, view_size); break; } else { unsigned int got_type = (optimized_type == tls::TLSOPT_TO_IE ? GOT_TYPE_TLS_NOFFSET : GOT_TYPE_TLS_DESC); unsigned int got_offset = 0; if (r_type == elfcpp::R_386_TLS_GOTDESC && optimized_type == tls::TLSOPT_NONE) { // We created GOT entries in the .got.tlsdesc portion of // the .got.plt section, but the offset stored in the // symbol is the offset within .got.tlsdesc. got_offset = (target->got_size() + target->got_plt_section()->data_size()); } if (gsym != NULL) { gold_assert(gsym->has_got_offset(got_type)); got_offset += gsym->got_offset(got_type) - 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_type)); got_offset += (object->local_got_offset(r_sym, got_type) - target->got_size()); } if (optimized_type == tls::TLSOPT_TO_IE) { gold_assert(tls_segment != NULL); this->tls_desc_gd_to_ie(relinfo, relnum, tls_segment, rel, r_type, got_offset, view, view_size); break; } else if (optimized_type == tls::TLSOPT_NONE) { if (r_type == elfcpp::R_386_TLS_GOTDESC) { // 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_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 if (optimized_type == tls::TLSOPT_TO_LE) { // This reloc can appear in debugging sections, in which // case we must not convert to local-exec. We decide what // to do based on whether the section is marked as // containing executable code. That is what the GNU linker // does as well. elfcpp::Shdr<32, false> shdr(relinfo->data_shdr); if ((shdr.get_sh_flags() & elfcpp::SHF_EXECINSTR) != 0) { 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_type = (r_type == elfcpp::R_386_TLS_IE_32 ? GOT_TYPE_TLS_OFFSET : GOT_TYPE_TLS_NOFFSET); unsigned int got_offset; if (gsym != NULL) { gold_assert(gsym->has_got_offset(got_type)); got_offset = gsym->got_offset(got_type); } else { unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info()); gold_assert(object->local_has_got_offset(r_sym, got_type)); got_offset = object->local_got_offset(r_sym, got_type); } // 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->options().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->options().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*, 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 the first (SIB) form. tls::check_tls(relinfo, relnum, rel.get_r_offset(), 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); } } 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_GOTDESC or TLS_DESC_CALL // General-Dynamic to a Local-Exec. inline void Target_i386::Relocate::tls_desc_gd_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) { if (r_type == elfcpp::R_386_TLS_GOTDESC) { // leal foo@TLSDESC(%ebx), %eax // ==> leal foo@NTPOFF, %eax tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2); tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4); tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[-2] == 0x8d && view[-1] == 0x83); view[-1] = 0x05; value -= tls_segment->memsz(); Relocate_functions<32, false>::rel32(view, value); } else { // call *foo@TLSCALL(%eax) // ==> nop; nop gold_assert(r_type == elfcpp::R_386_TLS_DESC_CALL); tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 2); tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[0] == 0xff && view[1] == 0x10); view[0] = 0x66; view[1] = 0x90; } } // Do a relocation in which we convert a TLS_GOTDESC or TLS_DESC_CALL // General-Dynamic to an Initial-Exec. inline void Target_i386::Relocate::tls_desc_gd_to_ie( const Relocate_info<32, false>* relinfo, size_t relnum, Output_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) { if (r_type == elfcpp::R_386_TLS_GOTDESC) { // leal foo@TLSDESC(%ebx), %eax // ==> movl 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, 4); tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[-2] == 0x8d && view[-1] == 0x83); view[-2] = 0x8b; Relocate_functions<32, false>::rel32(view, value); } else { // call *foo@TLSCALL(%eax) // ==> nop; nop gold_assert(r_type == elfcpp::R_386_TLS_DESC_CALL); tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 2); tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[0] == 0xff && view[1] == 0x10); view[0] = 0x66; view[1] = 0x90; } } // 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, const Reloc_symbol_changes* reloc_symbol_changes) { 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, reloc_symbol_changes); } // Return the size of a relocation while scanning during a relocatable // link. unsigned int Target_i386::Relocatable_size_for_reloc::get_size_for_reloc( unsigned int r_type, Relobj* object) { switch (r_type) { case elfcpp::R_386_NONE: case elfcpp::R_386_GNU_VTINHERIT: case elfcpp::R_386_GNU_VTENTRY: 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: return 0; case elfcpp::R_386_32: case elfcpp::R_386_PC32: case elfcpp::R_386_GOT32: case elfcpp::R_386_PLT32: case elfcpp::R_386_GOTOFF: case elfcpp::R_386_GOTPC: return 4; case elfcpp::R_386_16: case elfcpp::R_386_PC16: return 2; case elfcpp::R_386_8: case elfcpp::R_386_PC8: return 1; // 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_IRELATIVE: 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: object->error(_("unexpected reloc %u in object file"), r_type); return 0; 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: object->error(_("unsupported reloc %u in object file"), r_type); return 0; } } // Scan the relocs during a relocatable link. void Target_i386::scan_relocatable_relocs(Symbol_table* symtab, Layout* layout, Sized_relobj_file<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, Relocatable_relocs* rr) { gold_assert(sh_type == elfcpp::SHT_REL); typedef gold::Default_scan_relocatable_relocs<elfcpp::SHT_REL, Relocatable_size_for_reloc> Scan_relocatable_relocs; gold::scan_relocatable_relocs<32, false, elfcpp::SHT_REL, Scan_relocatable_relocs>( symtab, layout, object, data_shndx, prelocs, reloc_count, output_section, needs_special_offset_handling, local_symbol_count, plocal_symbols, rr); } // Relocate a section during a relocatable link. void Target_i386::relocate_for_relocatable( const Relocate_info<32, false>* relinfo, unsigned int sh_type, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, off_t offset_in_output_section, const Relocatable_relocs* rr, unsigned char* view, elfcpp::Elf_types<32>::Elf_Addr view_address, section_size_type view_size, unsigned char* reloc_view, section_size_type reloc_view_size) { gold_assert(sh_type == elfcpp::SHT_REL); gold::relocate_for_relocatable<32, false, elfcpp::SHT_REL>( relinfo, prelocs, reloc_count, output_section, offset_in_output_section, rr, view, view_address, view_size, reloc_view, reloc_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) const { 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<char*>(&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); } // Return whether SYM should be treated as a call to a non-split // function. We don't want that to be true of a call to a // get_pc_thunk function. bool Target_i386::do_is_call_to_non_split(const Symbol* sym, unsigned int) const { return (sym->type() == elfcpp::STT_FUNC && !is_prefix_of("__i686.get_pc_thunk.", sym->name())); } // FNOFFSET in section SHNDX in OBJECT is the start of a function // compiled with -fsplit-stack. The function calls non-split-stack // code. We have to change the function so that it always ensures // that it has enough stack space to run some random function. void Target_i386::do_calls_non_split(Relobj* object, unsigned int shndx, section_offset_type fnoffset, section_size_type fnsize, unsigned char* view, section_size_type view_size, std::string* from, std::string* to) const { // The function starts with a comparison of the stack pointer and a // field in the TCB. This is followed by a jump. // cmp %gs:NN,%esp if (this->match_view(view, view_size, fnoffset, "\x65\x3b\x25", 3) && fnsize > 7) { // We will call __morestack if the carry flag is set after this // comparison. We turn the comparison into an stc instruction // and some nops. view[fnoffset] = '\xf9'; this->set_view_to_nop(view, view_size, fnoffset + 1, 6); } // lea NN(%esp),%ecx // lea NN(%esp),%edx else if ((this->match_view(view, view_size, fnoffset, "\x8d\x8c\x24", 3) || this->match_view(view, view_size, fnoffset, "\x8d\x94\x24", 3)) && fnsize > 7) { // This is loading an offset from the stack pointer for a // comparison. The offset is negative, so we decrease the // offset by the amount of space we need for the stack. This // means we will avoid calling __morestack if there happens to // be plenty of space on the stack already. unsigned char* pval = view + fnoffset + 3; uint32_t val = elfcpp::Swap_unaligned<32, false>::readval(pval); val -= parameters->options().split_stack_adjust_size(); elfcpp::Swap_unaligned<32, false>::writeval(pval, val); } else { if (!object->has_no_split_stack()) object->error(_("failed to match split-stack sequence at " "section %u offset %0zx"), shndx, static_cast<size_t>(fnoffset)); return; } // We have to change the function so that it calls // __morestack_non_split instead of __morestack. The former will // allocate additional stack space. *from = "__morestack"; *to = "__morestack_non_split"; } // The selector for i386 object files. class Target_selector_i386 : public Target_selector_freebsd { public: Target_selector_i386() : Target_selector_freebsd(elfcpp::EM_386, 32, false, "elf32-i386", "elf32-i386-freebsd") { } Target* do_instantiate_target() { return new Target_i386(); } }; Target_selector_i386 target_selector_i386; } // End anonymous namespace.
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