// x86_64.cc -- x86_64 target support for gold. // Copyright (C) 2006-2018 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 "dwarf.h" #include "parameters.h" #include "reloc.h" #include "x86_64.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 "nacl.h" #include "gc.h" #include "icf.h" namespace { using namespace gold; // A class to handle the .got.plt section. class Output_data_got_plt_x86_64 : public Output_section_data_build { public: Output_data_got_plt_x86_64(Layout* layout) : Output_section_data_build(8), layout_(layout) { } Output_data_got_plt_x86_64(Layout* layout, off_t data_size) : Output_section_data_build(data_size, 8), layout_(layout) { } protected: // Write out the PLT data. void do_write(Output_file*); // Write to a map file. void do_print_to_mapfile(Mapfile* mapfile) const { mapfile->print_output_data(this, "** GOT PLT"); } private: // A pointer to the Layout class, so that we can find the .dynamic // section when we write out the GOT PLT section. Layout* layout_; }; // A class to handle the PLT data. // This is an abstract base class that handles most of the linker details // but does not know the actual contents of PLT entries. The derived // classes below fill in those details. template<int size> class Output_data_plt_x86_64 : public Output_section_data { public: typedef Output_data_reloc<elfcpp::SHT_RELA, true, size, false> Reloc_section; Output_data_plt_x86_64(Layout* layout, uint64_t addralign, Output_data_got<64, false>* got, Output_data_got_plt_x86_64* got_plt, Output_data_space* got_irelative) : Output_section_data(addralign), tlsdesc_rel_(NULL), irelative_rel_(NULL), got_(got), got_plt_(got_plt), got_irelative_(got_irelative), count_(0), irelative_count_(0), tlsdesc_got_offset_(-1U), free_list_() { this->init(layout); } Output_data_plt_x86_64(Layout* layout, uint64_t plt_entry_size, Output_data_got<64, false>* got, Output_data_got_plt_x86_64* got_plt, Output_data_space* got_irelative, unsigned int plt_count) : Output_section_data((plt_count + 1) * plt_entry_size, plt_entry_size, false), tlsdesc_rel_(NULL), irelative_rel_(NULL), got_(got), got_plt_(got_plt), got_irelative_(got_irelative), count_(plt_count), irelative_count_(0), tlsdesc_got_offset_(-1U), free_list_() { this->init(layout); // Initialize the free list and reserve the first entry. this->free_list_.init((plt_count + 1) * plt_entry_size, false); this->free_list_.remove(0, plt_entry_size); } // Initialize the PLT section. void init(Layout* layout); // Add an entry to the PLT. void add_entry(Symbol_table*, Layout*, Symbol* gsym); // Add an entry to the PLT for a local STT_GNU_IFUNC symbol. unsigned int add_local_ifunc_entry(Symbol_table* symtab, Layout*, Sized_relobj_file<size, false>* relobj, unsigned int local_sym_index); // Add the relocation for a PLT entry. void add_relocation(Symbol_table*, Layout*, Symbol* gsym, unsigned int got_offset); // Add the reserved TLSDESC_PLT entry to the PLT. void reserve_tlsdesc_entry(unsigned int got_offset) { this->tlsdesc_got_offset_ = got_offset; } // Return true if a TLSDESC_PLT entry has been reserved. bool has_tlsdesc_entry() const { return this->tlsdesc_got_offset_ != -1U; } // Return the GOT offset for the reserved TLSDESC_PLT entry. unsigned int get_tlsdesc_got_offset() const { return this->tlsdesc_got_offset_; } // Return the offset of the reserved TLSDESC_PLT entry. unsigned int get_tlsdesc_plt_offset() const { return ((this->count_ + this->irelative_count_ + 1) * this->get_plt_entry_size()); } // Return the .rela.plt section data. Reloc_section* rela_plt() { return this->rel_; } // Return where the TLSDESC relocations should go. Reloc_section* rela_tlsdesc(Layout*); // Return where the IRELATIVE relocations should go in the PLT // relocations. Reloc_section* rela_irelative(Symbol_table*, Layout*); // Return whether we created a section for IRELATIVE relocations. bool has_irelative_section() const { return this->irelative_rel_ != NULL; } // Get count of regular PLT entries. unsigned int regular_count() const { return this->count_; } // Return the total number of PLT entries. unsigned int entry_count() const { return this->count_ + this->irelative_count_; } // Return the offset of the first non-reserved PLT entry. unsigned int first_plt_entry_offset() { return this->get_plt_entry_size(); } // Return the size of a PLT entry. unsigned int get_plt_entry_size() const { return this->do_get_plt_entry_size(); } // Reserve a slot in the PLT for an existing symbol in an incremental update. void reserve_slot(unsigned int plt_index) { this->free_list_.remove((plt_index + 1) * this->get_plt_entry_size(), (plt_index + 2) * this->get_plt_entry_size()); } // Return the PLT address to use for a global symbol. uint64_t address_for_global(const Symbol* sym) { return do_address_for_global(sym); } // Return the PLT address to use for a local symbol. uint64_t address_for_local(const Relobj* obj, unsigned int symndx) { return do_address_for_local(obj, symndx); } // Add .eh_frame information for the PLT. void add_eh_frame(Layout* layout) { this->do_add_eh_frame(layout); } protected: Output_data_got<64, false>* got() const { return this->got_; } Output_data_got_plt_x86_64* got_plt() const { return this->got_plt_; } Output_data_space* got_irelative() const { return this->got_irelative_; } // Fill in the first PLT entry. void fill_first_plt_entry(unsigned char* pov, typename elfcpp::Elf_types<size>::Elf_Addr got_address, typename elfcpp::Elf_types<size>::Elf_Addr plt_address) { this->do_fill_first_plt_entry(pov, got_address, plt_address); } // Fill in a normal PLT entry. Returns the offset into the entry that // should be the initial GOT slot value. unsigned int fill_plt_entry(unsigned char* pov, typename elfcpp::Elf_types<size>::Elf_Addr got_address, typename elfcpp::Elf_types<size>::Elf_Addr plt_address, unsigned int got_offset, unsigned int plt_offset, unsigned int plt_index) { return this->do_fill_plt_entry(pov, got_address, plt_address, got_offset, plt_offset, plt_index); } // Fill in the reserved TLSDESC PLT entry. void fill_tlsdesc_entry(unsigned char* pov, typename elfcpp::Elf_types<size>::Elf_Addr got_address, typename elfcpp::Elf_types<size>::Elf_Addr plt_address, typename elfcpp::Elf_types<size>::Elf_Addr got_base, unsigned int tlsdesc_got_offset, unsigned int plt_offset) { this->do_fill_tlsdesc_entry(pov, got_address, plt_address, got_base, tlsdesc_got_offset, plt_offset); } virtual unsigned int do_get_plt_entry_size() const = 0; virtual void do_fill_first_plt_entry(unsigned char* pov, typename elfcpp::Elf_types<size>::Elf_Addr got_addr, typename elfcpp::Elf_types<size>::Elf_Addr plt_addr) = 0; virtual unsigned int do_fill_plt_entry(unsigned char* pov, typename elfcpp::Elf_types<size>::Elf_Addr got_address, typename elfcpp::Elf_types<size>::Elf_Addr plt_address, unsigned int got_offset, unsigned int plt_offset, unsigned int plt_index) = 0; virtual void do_fill_tlsdesc_entry(unsigned char* pov, typename elfcpp::Elf_types<size>::Elf_Addr got_address, typename elfcpp::Elf_types<size>::Elf_Addr plt_address, typename elfcpp::Elf_types<size>::Elf_Addr got_base, unsigned int tlsdesc_got_offset, unsigned int plt_offset) = 0; // Return the PLT address to use for a global symbol. virtual uint64_t do_address_for_global(const Symbol* sym); // Return the PLT address to use for a local symbol. virtual uint64_t do_address_for_local(const Relobj* obj, unsigned int symndx); virtual void do_add_eh_frame(Layout* layout) = 0; 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")); } // The CIE of the .eh_frame unwind information for the PLT. static const int plt_eh_frame_cie_size = 16; static const unsigned char plt_eh_frame_cie[plt_eh_frame_cie_size]; private: // Set the final size. void set_final_data_size(); // Write out the PLT data. void do_write(Output_file*); // The reloc section. Reloc_section* rel_; // The TLSDESC relocs, if necessary. These must follow the regular // PLT relocs. Reloc_section* tlsdesc_rel_; // The IRELATIVE relocs, if necessary. These must follow the // regular PLT relocations and the TLSDESC relocations. Reloc_section* irelative_rel_; // The .got section. Output_data_got<64, false>* got_; // The .got.plt section. Output_data_got_plt_x86_64* got_plt_; // The part of the .got.plt section used for IRELATIVE relocs. Output_data_space* got_irelative_; // The number of PLT entries. unsigned int count_; // Number of PLT entries with R_X86_64_IRELATIVE relocs. These // follow the regular PLT entries. unsigned int irelative_count_; // Offset of the reserved TLSDESC_GOT entry when needed. unsigned int tlsdesc_got_offset_; // List of available regions within the section, for incremental // update links. Free_list free_list_; }; template<int size> class Output_data_plt_x86_64_standard : public Output_data_plt_x86_64<size> { public: Output_data_plt_x86_64_standard(Layout* layout, Output_data_got<64, false>* got, Output_data_got_plt_x86_64* got_plt, Output_data_space* got_irelative) : Output_data_plt_x86_64<size>(layout, plt_entry_size, got, got_plt, got_irelative) { } Output_data_plt_x86_64_standard(Layout* layout, Output_data_got<64, false>* got, Output_data_got_plt_x86_64* got_plt, Output_data_space* got_irelative, unsigned int plt_count) : Output_data_plt_x86_64<size>(layout, plt_entry_size, got, got_plt, got_irelative, plt_count) { } protected: virtual unsigned int do_get_plt_entry_size() const { return plt_entry_size; } virtual void do_add_eh_frame(Layout* layout) { layout->add_eh_frame_for_plt(this, this->plt_eh_frame_cie, this->plt_eh_frame_cie_size, plt_eh_frame_fde, plt_eh_frame_fde_size); } virtual void do_fill_first_plt_entry(unsigned char* pov, typename elfcpp::Elf_types<size>::Elf_Addr got_addr, typename elfcpp::Elf_types<size>::Elf_Addr plt_addr); virtual unsigned int do_fill_plt_entry(unsigned char* pov, typename elfcpp::Elf_types<size>::Elf_Addr got_address, typename elfcpp::Elf_types<size>::Elf_Addr plt_address, unsigned int got_offset, unsigned int plt_offset, unsigned int plt_index); virtual void do_fill_tlsdesc_entry(unsigned char* pov, typename elfcpp::Elf_types<size>::Elf_Addr got_address, typename elfcpp::Elf_types<size>::Elf_Addr plt_address, typename elfcpp::Elf_types<size>::Elf_Addr got_base, unsigned int tlsdesc_got_offset, unsigned int plt_offset); private: // The size of an entry in the PLT. static const int plt_entry_size = 16; // The first entry in the PLT. // From the AMD64 ABI: "Unlike Intel386 ABI, this ABI uses the same // procedure linkage table for both programs and shared objects." static const unsigned char first_plt_entry[plt_entry_size]; // Other entries in the PLT for an executable. static const unsigned char plt_entry[plt_entry_size]; // The reserved TLSDESC entry in the PLT for an executable. static const unsigned char tlsdesc_plt_entry[plt_entry_size]; // The .eh_frame unwind information for the PLT. static const int plt_eh_frame_fde_size = 32; static const unsigned char plt_eh_frame_fde[plt_eh_frame_fde_size]; }; class Output_data_plt_x86_64_bnd : public Output_data_plt_x86_64<64> { public: Output_data_plt_x86_64_bnd(Layout* layout, Output_data_got<64, false>* got, Output_data_got_plt_x86_64* got_plt, Output_data_space* got_irelative) : Output_data_plt_x86_64<64>(layout, plt_entry_size, got, got_plt, got_irelative), aplt_offset_(0) { } Output_data_plt_x86_64_bnd(Layout* layout, Output_data_got<64, false>* got, Output_data_got_plt_x86_64* got_plt, Output_data_space* got_irelative, unsigned int plt_count) : Output_data_plt_x86_64<64>(layout, plt_entry_size, got, got_plt, got_irelative, plt_count), aplt_offset_(0) { } protected: virtual unsigned int do_get_plt_entry_size() const { return plt_entry_size; } // Return the PLT address to use for a global symbol. uint64_t do_address_for_global(const Symbol*); // Return the PLT address to use for a local symbol. uint64_t do_address_for_local(const Relobj*, unsigned int symndx); virtual void do_add_eh_frame(Layout* layout) { layout->add_eh_frame_for_plt(this, this->plt_eh_frame_cie, this->plt_eh_frame_cie_size, plt_eh_frame_fde, plt_eh_frame_fde_size); } virtual void do_fill_first_plt_entry(unsigned char* pov, elfcpp::Elf_types<64>::Elf_Addr got_addr, elfcpp::Elf_types<64>::Elf_Addr plt_addr); virtual unsigned int do_fill_plt_entry(unsigned char* pov, elfcpp::Elf_types<64>::Elf_Addr got_address, elfcpp::Elf_types<64>::Elf_Addr plt_address, unsigned int got_offset, unsigned int plt_offset, unsigned int plt_index); virtual void do_fill_tlsdesc_entry(unsigned char* pov, elfcpp::Elf_types<64>::Elf_Addr got_address, elfcpp::Elf_types<64>::Elf_Addr plt_address, elfcpp::Elf_types<64>::Elf_Addr got_base, unsigned int tlsdesc_got_offset, unsigned int plt_offset); void fill_aplt_entry(unsigned char* pov, elfcpp::Elf_types<64>::Elf_Addr got_address, elfcpp::Elf_types<64>::Elf_Addr plt_address, unsigned int got_offset, unsigned int plt_offset, unsigned int plt_index); private: // Set the final size. void set_final_data_size(); // Write out the BND PLT data. void do_write(Output_file*); // Offset of the Additional PLT (if using -z bndplt). unsigned int aplt_offset_; // The size of an entry in the PLT. static const int plt_entry_size = 16; // The size of an entry in the additional PLT. static const int aplt_entry_size = 8; // The first entry in the PLT. // From the AMD64 ABI: "Unlike Intel386 ABI, this ABI uses the same // procedure linkage table for both programs and shared objects." static const unsigned char first_plt_entry[plt_entry_size]; // Other entries in the PLT for an executable. static const unsigned char plt_entry[plt_entry_size]; // Entries in the additional PLT. static const unsigned char aplt_entry[aplt_entry_size]; // The reserved TLSDESC entry in the PLT for an executable. static const unsigned char tlsdesc_plt_entry[plt_entry_size]; // The .eh_frame unwind information for the PLT. static const int plt_eh_frame_fde_size = 32; static const unsigned char plt_eh_frame_fde[plt_eh_frame_fde_size]; }; // We use this PLT when Indirect Branch Tracking (IBT) is enabled. template <int size> class Output_data_plt_x86_64_ibt : public Output_data_plt_x86_64<size> { public: Output_data_plt_x86_64_ibt(Layout* layout, Output_data_got<64, false>* got, Output_data_got_plt_x86_64* got_plt, Output_data_space* got_irelative) : Output_data_plt_x86_64<size>(layout, plt_entry_size, got, got_plt, got_irelative), aplt_offset_(0) { } Output_data_plt_x86_64_ibt(Layout* layout, Output_data_got<64, false>* got, Output_data_got_plt_x86_64* got_plt, Output_data_space* got_irelative, unsigned int plt_count) : Output_data_plt_x86_64<size>(layout, plt_entry_size, got, got_plt, got_irelative, plt_count), aplt_offset_(0) { } protected: virtual unsigned int do_get_plt_entry_size() const { return plt_entry_size; } // Return the PLT address to use for a global symbol. uint64_t do_address_for_global(const Symbol*); // Return the PLT address to use for a local symbol. uint64_t do_address_for_local(const Relobj*, unsigned int symndx); virtual void do_add_eh_frame(Layout* layout) { layout->add_eh_frame_for_plt(this, this->plt_eh_frame_cie, this->plt_eh_frame_cie_size, plt_eh_frame_fde, plt_eh_frame_fde_size); } virtual void do_fill_first_plt_entry(unsigned char* pov, typename elfcpp::Elf_types<size>::Elf_Addr got_addr, typename elfcpp::Elf_types<size>::Elf_Addr plt_addr); virtual unsigned int do_fill_plt_entry(unsigned char* pov, typename elfcpp::Elf_types<size>::Elf_Addr got_address, typename elfcpp::Elf_types<size>::Elf_Addr plt_address, unsigned int got_offset, unsigned int plt_offset, unsigned int plt_index); virtual void do_fill_tlsdesc_entry(unsigned char* pov, typename elfcpp::Elf_types<size>::Elf_Addr got_address, typename elfcpp::Elf_types<size>::Elf_Addr plt_address, typename elfcpp::Elf_types<size>::Elf_Addr got_base, unsigned int tlsdesc_got_offset, unsigned int plt_offset); void fill_aplt_entry(unsigned char* pov, typename elfcpp::Elf_types<size>::Elf_Addr got_address, typename elfcpp::Elf_types<size>::Elf_Addr plt_address, unsigned int got_offset, unsigned int plt_offset, unsigned int plt_index); private: // Set the final size. void set_final_data_size(); // Write out the BND PLT data. void do_write(Output_file*); // Offset of the Additional PLT (if using -z bndplt). unsigned int aplt_offset_; // The size of an entry in the PLT. static const int plt_entry_size = 16; // The size of an entry in the additional PLT. static const int aplt_entry_size = 16; // The first entry in the PLT. // From the AMD64 ABI: "Unlike Intel386 ABI, this ABI uses the same // procedure linkage table for both programs and shared objects." static const unsigned char first_plt_entry[plt_entry_size]; // Other entries in the PLT for an executable. static const unsigned char plt_entry[plt_entry_size]; // Entries in the additional PLT. static const unsigned char aplt_entry[aplt_entry_size]; // The reserved TLSDESC entry in the PLT for an executable. static const unsigned char tlsdesc_plt_entry[plt_entry_size]; // The .eh_frame unwind information for the PLT. static const int plt_eh_frame_fde_size = 32; static const unsigned char plt_eh_frame_fde[plt_eh_frame_fde_size]; }; template<int size> class Lazy_view { public: Lazy_view(Sized_relobj_file<size, false>* object, unsigned int data_shndx) : object_(object), data_shndx_(data_shndx), view_(NULL), view_size_(0) { } inline unsigned char operator[](size_t offset) { if (this->view_ == NULL) this->view_ = this->object_->section_contents(this->data_shndx_, &this->view_size_, true); if (offset >= this->view_size_) return 0; return this->view_[offset]; } private: Sized_relobj_file<size, false>* object_; unsigned int data_shndx_; const unsigned char* view_; section_size_type view_size_; }; // The x86_64 target class. // See the ABI at // http://www.x86-64.org/documentation/abi.pdf // TLS info comes from // http://people.redhat.com/drepper/tls.pdf // http://www.lsd.ic.unicamp.br/~oliva/writeups/TLS/RFC-TLSDESC-x86.txt template<int size> class Target_x86_64 : public Sized_target<size, false> { public: // In the x86_64 ABI (p 68), it says "The AMD64 ABI architectures // uses only Elf64_Rela relocation entries with explicit addends." typedef Output_data_reloc<elfcpp::SHT_RELA, true, size, false> Reloc_section; Target_x86_64(const Target::Target_info* info = &x86_64_info) : Sized_target<size, false>(info), got_(NULL), plt_(NULL), got_plt_(NULL), got_irelative_(NULL), got_tlsdesc_(NULL), global_offset_table_(NULL), rela_dyn_(NULL), rela_irelative_(NULL), copy_relocs_(elfcpp::R_X86_64_COPY), got_mod_index_offset_(-1U), tlsdesc_reloc_info_(), tls_base_symbol_defined_(false), isa_1_used_(0), isa_1_needed_(0), feature_1_(0), object_feature_1_(0), seen_first_object_(false) { } // Hook for a new output section. void do_new_output_section(Output_section*) const; // Scan the relocations to look for symbol adjustments. void gc_process_relocs(Symbol_table* symtab, Layout* layout, Sized_relobj_file<size, 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<size, 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<size, 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, typename elfcpp::Elf_types<size>::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<size, 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*); // Scan the relocs for --emit-relocs. void emit_relocs_scan(Symbol_table* symtab, Layout* layout, Sized_relobj_file<size, 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_syms, Relocatable_relocs* rr); // Emit relocations for a section. void relocate_relocs( const Relocate_info<size, false>*, unsigned int sh_type, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, typename elfcpp::Elf_types<size>::Elf_Off offset_in_output_section, unsigned char* view, typename elfcpp::Elf_types<size>::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 the symbol index to use for a target specific relocation. // The only target specific relocation is R_X86_64_TLSDESC for a // local symbol, which is an absolute reloc. unsigned int do_reloc_symbol_index(void*, unsigned int r_type) const { gold_assert(r_type == elfcpp::R_X86_64_TLSDESC); return 0; } // Return the addend to use for a target specific relocation. uint64_t do_reloc_addend(void* arg, unsigned int r_type, uint64_t addend) const; // Return the PLT section. uint64_t do_plt_address_for_global(const Symbol* gsym) const { return this->plt_section()->address_for_global(gsym); } uint64_t do_plt_address_for_local(const Relobj* relobj, unsigned int symndx) const { return this->plt_section()->address_for_local(relobj, symndx); } // This function should be defined in targets that can use relocation // types to determine (implemented in local_reloc_may_be_function_pointer // and global_reloc_may_be_function_pointer) // if a function's pointer is taken. ICF uses this in safe mode to only // fold those functions whose pointer is defintely not taken. For x86_64 // pie binaries, safe ICF cannot be done by looking at only relocation // types, and for certain cases (e.g. R_X86_64_PC32), the instruction // opcode is checked as well to distinguish a function call from taking // a function's pointer. bool do_can_check_for_function_pointers() const { return true; } // Return the base for a DW_EH_PE_datarel encoding. uint64_t do_ehframe_datarel_base() 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, const unsigned char* prelocs, size_t reloc_count, 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() / 8; } // 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; // Return the size of each GOT entry. unsigned int got_entry_size() const { return 8; }; // Create the GOT section for an incremental update. Output_data_got_base* init_got_plt_for_update(Symbol_table* symtab, Layout* layout, unsigned int got_count, unsigned int plt_count); // Reserve a GOT entry for a local symbol, and regenerate any // necessary dynamic relocations. void reserve_local_got_entry(unsigned int got_index, Sized_relobj<size, false>* obj, unsigned int r_sym, unsigned int got_type); // Reserve a GOT entry for a global symbol, and regenerate any // necessary dynamic relocations. void reserve_global_got_entry(unsigned int got_index, Symbol* gsym, unsigned int got_type); // Register an existing PLT entry for a global symbol. void register_global_plt_entry(Symbol_table*, Layout*, unsigned int plt_index, Symbol* gsym); // Force a COPY relocation for a given symbol. void emit_copy_reloc(Symbol_table*, Symbol*, Output_section*, off_t); // Apply an incremental relocation. void apply_relocation(const Relocate_info<size, false>* relinfo, typename elfcpp::Elf_types<size>::Elf_Addr r_offset, unsigned int r_type, typename elfcpp::Elf_types<size>::Elf_Swxword r_addend, const Symbol* gsym, unsigned char* view, typename elfcpp::Elf_types<size>::Elf_Addr address, section_size_type view_size); // Add a new reloc argument, returning the index in the vector. size_t add_tlsdesc_info(Sized_relobj_file<size, false>* object, unsigned int r_sym) { this->tlsdesc_reloc_info_.push_back(Tlsdesc_info(object, r_sym)); return this->tlsdesc_reloc_info_.size() - 1; } Output_data_plt_x86_64<size>* make_data_plt(Layout* layout, Output_data_got<64, false>* got, Output_data_got_plt_x86_64* got_plt, Output_data_space* got_irelative) { return this->do_make_data_plt(layout, got, got_plt, got_irelative); } Output_data_plt_x86_64<size>* make_data_plt(Layout* layout, Output_data_got<64, false>* got, Output_data_got_plt_x86_64* got_plt, Output_data_space* got_irelative, unsigned int plt_count) { return this->do_make_data_plt(layout, got, got_plt, got_irelative, plt_count); } virtual Output_data_plt_x86_64<size>* do_make_data_plt(Layout* layout, Output_data_got<64, false>* got, Output_data_got_plt_x86_64* got_plt, Output_data_space* got_irelative); virtual Output_data_plt_x86_64<size>* do_make_data_plt(Layout* layout, Output_data_got<64, false>* got, Output_data_got_plt_x86_64* got_plt, Output_data_space* got_irelative, unsigned int plt_count); private: // The class which scans relocations. class Scan { public: Scan() : issued_non_pic_error_(false) { } static inline int get_reference_flags(unsigned int r_type); inline void local(Symbol_table* symtab, Layout* layout, Target_x86_64* target, Sized_relobj_file<size, false>* object, unsigned int data_shndx, Output_section* output_section, const elfcpp::Rela<size, false>& reloc, unsigned int r_type, const elfcpp::Sym<size, false>& lsym, bool is_discarded); inline void global(Symbol_table* symtab, Layout* layout, Target_x86_64* target, Sized_relobj_file<size, false>* object, unsigned int data_shndx, Output_section* output_section, const elfcpp::Rela<size, false>& reloc, unsigned int r_type, Symbol* gsym); inline bool local_reloc_may_be_function_pointer(Symbol_table* symtab, Layout* layout, Target_x86_64* target, Sized_relobj_file<size, false>* object, unsigned int data_shndx, Output_section* output_section, const elfcpp::Rela<size, false>& reloc, unsigned int r_type, const elfcpp::Sym<size, false>& lsym); inline bool global_reloc_may_be_function_pointer(Symbol_table* symtab, Layout* layout, Target_x86_64* target, Sized_relobj_file<size, false>* object, unsigned int data_shndx, Output_section* output_section, const elfcpp::Rela<size, false>& reloc, unsigned int r_type, Symbol* gsym); private: static void unsupported_reloc_local(Sized_relobj_file<size, false>*, unsigned int r_type); static void unsupported_reloc_global(Sized_relobj_file<size, false>*, unsigned int r_type, Symbol*); void check_non_pic(Relobj*, unsigned int r_type, Symbol*); inline bool possible_function_pointer_reloc(Sized_relobj_file<size, false>* src_obj, unsigned int src_indx, unsigned int r_offset, unsigned int r_type); bool reloc_needs_plt_for_ifunc(Sized_relobj_file<size, false>*, unsigned int r_type); // Whether we have issued an error about a non-PIC compilation. bool issued_non_pic_error_; }; // The class which implements relocation. class Relocate { public: Relocate() : skip_call_tls_get_addr_(false) { } ~Relocate() { if (this->skip_call_tls_get_addr_) { // FIXME: This needs to specify the location somehow. gold_error(_("missing expected TLS relocation")); } } // Do a relocation. Return false if the caller should not issue // any warnings about this relocation. inline bool relocate(const Relocate_info<size, false>*, unsigned int, Target_x86_64*, Output_section*, size_t, const unsigned char*, const Sized_symbol<size>*, const Symbol_value<size>*, unsigned char*, typename elfcpp::Elf_types<size>::Elf_Addr, section_size_type); private: // Do a TLS relocation. inline void relocate_tls(const Relocate_info<size, false>*, Target_x86_64*, size_t relnum, const elfcpp::Rela<size, false>&, unsigned int r_type, const Sized_symbol<size>*, const Symbol_value<size>*, unsigned char*, typename elfcpp::Elf_types<size>::Elf_Addr, section_size_type); // Do a TLS General-Dynamic to Initial-Exec transition. inline void tls_gd_to_ie(const Relocate_info<size, false>*, size_t relnum, const elfcpp::Rela<size, false>&, unsigned int r_type, typename elfcpp::Elf_types<size>::Elf_Addr value, unsigned char* view, typename elfcpp::Elf_types<size>::Elf_Addr, section_size_type view_size); // Do a TLS General-Dynamic to Local-Exec transition. inline void tls_gd_to_le(const Relocate_info<size, false>*, size_t relnum, Output_segment* tls_segment, const elfcpp::Rela<size, false>&, unsigned int r_type, typename elfcpp::Elf_types<size>::Elf_Addr value, unsigned char* view, section_size_type view_size); // Do a TLSDESC-style General-Dynamic to Initial-Exec transition. inline void tls_desc_gd_to_ie(const Relocate_info<size, false>*, size_t relnum, const elfcpp::Rela<size, false>&, unsigned int r_type, typename elfcpp::Elf_types<size>::Elf_Addr value, unsigned char* view, typename elfcpp::Elf_types<size>::Elf_Addr, section_size_type view_size); // Do a TLSDESC-style General-Dynamic to Local-Exec transition. inline void tls_desc_gd_to_le(const Relocate_info<size, false>*, size_t relnum, Output_segment* tls_segment, const elfcpp::Rela<size, false>&, unsigned int r_type, typename elfcpp::Elf_types<size>::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<size, false>*, size_t relnum, Output_segment* tls_segment, const elfcpp::Rela<size, false>&, unsigned int r_type, typename elfcpp::Elf_types<size>::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<size, false>*, size_t relnum, Output_segment* tls_segment, const elfcpp::Rela<size, false>&, unsigned int r_type, typename elfcpp::Elf_types<size>::Elf_Addr value, unsigned char* view, section_size_type view_size); // 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_; }; // Check if relocation against this symbol is a candidate for // conversion from // mov foo@GOTPCREL(%rip), %reg // to lea foo(%rip), %reg. template<class View_type> static inline bool can_convert_mov_to_lea(const Symbol* gsym, unsigned int r_type, size_t r_offset, View_type* view) { gold_assert(gsym != NULL); // We cannot do the conversion unless it's one of these relocations. if (r_type != elfcpp::R_X86_64_GOTPCREL && r_type != elfcpp::R_X86_64_GOTPCRELX && r_type != elfcpp::R_X86_64_REX_GOTPCRELX) return false; // We cannot convert references to IFUNC symbols, or to symbols that // are not local to the current module. // We can't do predefined symbols because they may become undefined // (e.g., __ehdr_start when the headers aren't mapped to a segment). if (gsym->type() == elfcpp::STT_GNU_IFUNC || gsym->is_undefined() || gsym->is_predefined() || gsym->is_from_dynobj() || gsym->is_preemptible()) return false; // If we are building a shared object and the symbol is protected, we may // need to go through the GOT. if (parameters->options().shared() && gsym->visibility() == elfcpp::STV_PROTECTED) return false; // We cannot convert references to the _DYNAMIC symbol. if (strcmp(gsym->name(), "_DYNAMIC") == 0) return false; // Check for a MOV opcode. return (*view)[r_offset - 2] == 0x8b; } // Convert // callq *foo@GOTPCRELX(%rip) to // addr32 callq foo // and jmpq *foo@GOTPCRELX(%rip) to // jmpq foo // nop template<class View_type> static inline bool can_convert_callq_to_direct(const Symbol* gsym, unsigned int r_type, size_t r_offset, View_type* view) { gold_assert(gsym != NULL); // We cannot do the conversion unless it's a GOTPCRELX relocation. if (r_type != elfcpp::R_X86_64_GOTPCRELX) return false; // We cannot convert references to IFUNC symbols, or to symbols that // are not local to the current module. if (gsym->type() == elfcpp::STT_GNU_IFUNC || gsym->is_undefined () || gsym->is_from_dynobj() || gsym->is_preemptible()) return false; // Check for a CALLQ or JMPQ opcode. return ((*view)[r_offset - 2] == 0xff && ((*view)[r_offset - 1] == 0x15 || (*view)[r_offset - 1] == 0x25)); } // 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<64, false>* got_section(Symbol_table*, Layout*); // Get the GOT PLT section. Output_data_got_plt_x86_64* got_plt_section() const { gold_assert(this->got_plt_ != NULL); return this->got_plt_; } // Get the GOT section for TLSDESC entries. Output_data_got<64, 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<size, 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 the reserved PLT and GOT entries for the TLS descriptor resolver. void reserve_tlsdesc_entries(Symbol_table* symtab, Layout* layout); // Create a GOT entry for the TLS module index. unsigned int got_mod_index_entry(Symbol_table* symtab, Layout* layout, Sized_relobj_file<size, false>* object); // Get the PLT section. Output_data_plt_x86_64<size>* plt_section() const { gold_assert(this->plt_ != NULL); return this->plt_; } // Get the dynamic reloc section, creating it if necessary. Reloc_section* rela_dyn_section(Layout*); // Get the section to use for TLSDESC relocations. Reloc_section* rela_tlsdesc_section(Layout*) const; // Get the section to use for IRELATIVE relocations. Reloc_section* rela_irelative_section(Layout*); // Add a potential copy relocation. void copy_reloc(Symbol_table* symtab, Layout* layout, Sized_relobj_file<size, false>* object, unsigned int shndx, Output_section* output_section, Symbol* sym, const elfcpp::Rela<size, false>& reloc) { unsigned int r_type = elfcpp::elf_r_type<size>(reloc.get_r_info()); this->copy_relocs_.copy_reloc(symtab, layout, symtab->get_sized_symbol<size>(sym), object, shndx, output_section, r_type, reloc.get_r_offset(), reloc.get_r_addend(), this->rela_dyn_section(layout)); } // Record a target-specific program property in the .note.gnu.property // section. void record_gnu_property(int, int, size_t, const unsigned char*, const Object*); // Merge the target-specific program properties from the current object. void merge_gnu_properties(const Object*); // Finalize the target-specific program properties and add them back to // the layout. void do_finalize_gnu_properties(Layout*) const; // Information about this specific target which we pass to the // general Target structure. static const Target::Target_info x86_64_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_OFFSET = 1, // GOT entry for TLS offset GOT_TYPE_TLS_PAIR = 2, // GOT entry for TLS module/offset pair GOT_TYPE_TLS_DESC = 3 // GOT entry for TLS_DESC pair }; // This type is used as the argument to the target specific // relocation routines. The only target specific reloc is // R_X86_64_TLSDESC against a local symbol. struct Tlsdesc_info { Tlsdesc_info(Sized_relobj_file<size, false>* a_object, unsigned int a_r_sym) : object(a_object), r_sym(a_r_sym) { } // The object in which the local symbol is defined. Sized_relobj_file<size, false>* object; // The local symbol index in the object. unsigned int r_sym; }; // The GOT section. Output_data_got<64, false>* got_; // The PLT section. Output_data_plt_x86_64<size>* plt_; // The GOT PLT section. Output_data_got_plt_x86_64* got_plt_; // The GOT section for IRELATIVE relocations. Output_data_space* got_irelative_; // The GOT section for TLSDESC relocations. Output_data_got<64, false>* got_tlsdesc_; // The _GLOBAL_OFFSET_TABLE_ symbol. Symbol* global_offset_table_; // The dynamic reloc section. Reloc_section* rela_dyn_; // The section to use for IRELATIVE relocs. Reloc_section* rela_irelative_; // Relocs saved to avoid a COPY reloc. Copy_relocs<elfcpp::SHT_RELA, size, false> copy_relocs_; // Offset of the GOT entry for the TLS module index. unsigned int got_mod_index_offset_; // We handle R_X86_64_TLSDESC against a local symbol as a target // specific relocation. Here we store the object and local symbol // index for the relocation. std::vector<Tlsdesc_info> tlsdesc_reloc_info_; // True if the _TLS_MODULE_BASE_ symbol has been defined. bool tls_base_symbol_defined_; // Target-specific program properties, from .note.gnu.property section. // Each bit represents a specific feature. uint32_t isa_1_used_; uint32_t isa_1_needed_; uint32_t feature_1_; // Target-specific properties from the current object. // These bits get ANDed into FEATURE_1_ after all properties for the object // have been processed. uint32_t object_feature_1_; // Whether we have seen our first object, for use in initializing FEATURE_1_. bool seen_first_object_; }; template<> const Target::Target_info Target_x86_64<64>::x86_64_info = { 64, // size false, // is_big_endian elfcpp::EM_X86_64, // machine_code false, // has_make_symbol false, // has_resolve true, // has_code_fill true, // is_default_stack_executable true, // can_icf_inline_merge_sections '\0', // wrap_char "/lib/ld64.so.1", // program interpreter 0x400000, // default_text_segment_address 0x1000, // abi_pagesize (overridable by -z max-page-size) 0x1000, // common_pagesize (overridable by -z common-page-size) false, // isolate_execinstr 0, // rosegment_gap elfcpp::SHN_UNDEF, // small_common_shndx elfcpp::SHN_X86_64_LCOMMON, // large_common_shndx 0, // small_common_section_flags elfcpp::SHF_X86_64_LARGE, // large_common_section_flags NULL, // attributes_section NULL, // attributes_vendor "_start", // entry_symbol_name 32, // hash_entry_size elfcpp::SHT_X86_64_UNWIND, // unwind_section_type }; template<> const Target::Target_info Target_x86_64<32>::x86_64_info = { 32, // size false, // is_big_endian elfcpp::EM_X86_64, // machine_code false, // has_make_symbol false, // has_resolve true, // has_code_fill true, // is_default_stack_executable true, // can_icf_inline_merge_sections '\0', // wrap_char "/libx32/ldx32.so.1", // program interpreter 0x400000, // default_text_segment_address 0x1000, // abi_pagesize (overridable by -z max-page-size) 0x1000, // common_pagesize (overridable by -z common-page-size) false, // isolate_execinstr 0, // rosegment_gap elfcpp::SHN_UNDEF, // small_common_shndx elfcpp::SHN_X86_64_LCOMMON, // large_common_shndx 0, // small_common_section_flags elfcpp::SHF_X86_64_LARGE, // large_common_section_flags NULL, // attributes_section NULL, // attributes_vendor "_start", // entry_symbol_name 32, // hash_entry_size elfcpp::SHT_X86_64_UNWIND, // unwind_section_type }; // This is called when a new output section is created. This is where // we handle the SHF_X86_64_LARGE. template<int size> void Target_x86_64<size>::do_new_output_section(Output_section* os) const { if ((os->flags() & elfcpp::SHF_X86_64_LARGE) != 0) os->set_is_large_section(); } // Get the GOT section, creating it if necessary. template<int size> Output_data_got<64, false>* Target_x86_64<size>::got_section(Symbol_table* symtab, Layout* layout) { if (this->got_ == NULL) { gold_assert(symtab != NULL && layout != NULL); // When using -z now, we can treat .got.plt as a relro section. // Without -z now, it is modified after program startup by lazy // PLT relocations. bool is_got_plt_relro = parameters->options().now(); Output_section_order got_order = (is_got_plt_relro ? ORDER_RELRO : ORDER_RELRO_LAST); Output_section_order got_plt_order = (is_got_plt_relro ? ORDER_RELRO : ORDER_NON_RELRO_FIRST); this->got_ = new Output_data_got<64, false>(); layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS, (elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE), this->got_, got_order, true); this->got_plt_ = new Output_data_got_plt_x86_64(layout); layout->add_output_section_data(".got.plt", elfcpp::SHT_PROGBITS, (elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE), this->got_plt_, got_plt_order, is_got_plt_relro); // The first three entries are reserved. this->got_plt_->set_current_data_size(3 * 8); if (!is_got_plt_relro) { // Those bytes can go into the relro segment. layout->increase_relro(3 * 8); } // 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 IRELATIVE relocations, they get GOT entries // in .got.plt after the jump slot entries. this->got_irelative_ = new Output_data_space(8, "** GOT IRELATIVE PLT"); layout->add_output_section_data(".got.plt", elfcpp::SHT_PROGBITS, (elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE), this->got_irelative_, got_plt_order, is_got_plt_relro); // If there are any TLSDESC relocations, they get GOT entries in // .got.plt after the jump slot and IRELATIVE entries. this->got_tlsdesc_ = new Output_data_got<64, false>(); layout->add_output_section_data(".got.plt", elfcpp::SHT_PROGBITS, (elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE), this->got_tlsdesc_, got_plt_order, is_got_plt_relro); } return this->got_; } // Get the dynamic reloc section, creating it if necessary. template<int size> typename Target_x86_64<size>::Reloc_section* Target_x86_64<size>::rela_dyn_section(Layout* layout) { if (this->rela_dyn_ == NULL) { gold_assert(layout != NULL); this->rela_dyn_ = new Reloc_section(parameters->options().combreloc()); layout->add_output_section_data(".rela.dyn", elfcpp::SHT_RELA, elfcpp::SHF_ALLOC, this->rela_dyn_, ORDER_DYNAMIC_RELOCS, false); } return this->rela_dyn_; } // Get the section to use for IRELATIVE relocs, creating it if // necessary. These go in .rela.dyn, but only after all other dynamic // relocations. They need to follow the other dynamic relocations so // that they can refer to global variables initialized by those // relocs. template<int size> typename Target_x86_64<size>::Reloc_section* Target_x86_64<size>::rela_irelative_section(Layout* layout) { if (this->rela_irelative_ == NULL) { // Make sure we have already created the dynamic reloc section. this->rela_dyn_section(layout); this->rela_irelative_ = new Reloc_section(false); layout->add_output_section_data(".rela.dyn", elfcpp::SHT_RELA, elfcpp::SHF_ALLOC, this->rela_irelative_, ORDER_DYNAMIC_RELOCS, false); gold_assert(this->rela_dyn_->output_section() == this->rela_irelative_->output_section()); } return this->rela_irelative_; } // Record a target-specific program property from the .note.gnu.property // section. template<int size> void Target_x86_64<size>::record_gnu_property( int, int pr_type, size_t pr_datasz, const unsigned char* pr_data, const Object* object) { uint32_t val = 0; switch (pr_type) { case elfcpp::GNU_PROPERTY_X86_ISA_1_USED: case elfcpp::GNU_PROPERTY_X86_ISA_1_NEEDED: case elfcpp::GNU_PROPERTY_X86_FEATURE_1_AND: if (pr_datasz != 4) { gold_warning(_("%s: corrupt .note.gnu.property section " "(pr_datasz for property %d is not 4)"), object->name().c_str(), pr_type); return; } val = elfcpp::Swap<32, false>::readval(pr_data); break; default: gold_warning(_("%s: unknown program property type 0x%x " "in .note.gnu.property section"), object->name().c_str(), pr_type); break; } switch (pr_type) { case elfcpp::GNU_PROPERTY_X86_ISA_1_USED: this->isa_1_used_ |= val; break; case elfcpp::GNU_PROPERTY_X86_ISA_1_NEEDED: this->isa_1_needed_ |= val; break; case elfcpp::GNU_PROPERTY_X86_FEATURE_1_AND: // If we see multiple feature props in one object, OR them together. this->object_feature_1_ |= val; break; } } // Merge the target-specific program properties from the current object. template<int size> void Target_x86_64<size>::merge_gnu_properties(const Object*) { if (this->seen_first_object_) this->feature_1_ &= this->object_feature_1_; else { this->feature_1_ = this->object_feature_1_; this->seen_first_object_ = true; } this->object_feature_1_ = 0; } static inline void add_property(Layout* layout, unsigned int pr_type, uint32_t val) { unsigned char buf[4]; elfcpp::Swap<32, false>::writeval(buf, val); layout->add_gnu_property(elfcpp::NT_GNU_PROPERTY_TYPE_0, pr_type, 4, buf); } // Finalize the target-specific program properties and add them back to // the layout. template<int size> void Target_x86_64<size>::do_finalize_gnu_properties(Layout* layout) const { if (this->isa_1_used_ != 0) add_property(layout, elfcpp::GNU_PROPERTY_X86_ISA_1_USED, this->isa_1_used_); if (this->isa_1_needed_ != 0) add_property(layout, elfcpp::GNU_PROPERTY_X86_ISA_1_NEEDED, this->isa_1_needed_); if (this->feature_1_ != 0) add_property(layout, elfcpp::GNU_PROPERTY_X86_FEATURE_1_AND, this->feature_1_); } // Write the first three reserved words of the .got.plt section. // The remainder of the section is written while writing the PLT // in Output_data_plt_i386::do_write. void Output_data_got_plt_x86_64::do_write(Output_file* of) { // The first entry in the GOT is the address of the .dynamic section // aka the PT_DYNAMIC segment. The next two entries are reserved. // We saved space for them when we created the section in // Target_x86_64::got_section. const off_t got_file_offset = this->offset(); gold_assert(this->data_size() >= 24); unsigned char* const got_view = of->get_output_view(got_file_offset, 24); Output_section* dynamic = this->layout_->dynamic_section(); uint64_t dynamic_addr = dynamic == NULL ? 0 : dynamic->address(); elfcpp::Swap<64, false>::writeval(got_view, dynamic_addr); memset(got_view + 8, 0, 16); of->write_output_view(got_file_offset, 24, got_view); } // Initialize the PLT section. template<int size> void Output_data_plt_x86_64<size>::init(Layout* layout) { this->rel_ = new Reloc_section(false); layout->add_output_section_data(".rela.plt", elfcpp::SHT_RELA, elfcpp::SHF_ALLOC, this->rel_, ORDER_DYNAMIC_PLT_RELOCS, false); } template<int size> void Output_data_plt_x86_64<size>::do_adjust_output_section(Output_section* os) { os->set_entsize(this->get_plt_entry_size()); } // Add an entry to the PLT. template<int size> void Output_data_plt_x86_64<size>::add_entry(Symbol_table* symtab, Layout* layout, Symbol* gsym) { gold_assert(!gsym->has_plt_offset()); unsigned int plt_index; off_t plt_offset; section_offset_type got_offset; unsigned int* pcount; unsigned int offset; unsigned int reserved; Output_section_data_build* got; if (gsym->type() == elfcpp::STT_GNU_IFUNC && gsym->can_use_relative_reloc(false)) { pcount = &this->irelative_count_; offset = 0; reserved = 0; got = this->got_irelative_; } else { pcount = &this->count_; offset = 1; reserved = 3; got = this->got_plt_; } if (!this->is_data_size_valid()) { // Note that when setting the PLT offset for a non-IRELATIVE // entry we skip the initial reserved PLT entry. plt_index = *pcount + offset; plt_offset = plt_index * this->get_plt_entry_size(); ++*pcount; got_offset = (plt_index - offset + reserved) * 8; gold_assert(got_offset == got->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). got->set_current_data_size(got_offset + 8); } else { // FIXME: This is probably not correct for IRELATIVE relocs. // For incremental updates, find an available slot. plt_offset = this->free_list_.allocate(this->get_plt_entry_size(), this->get_plt_entry_size(), 0); if (plt_offset == -1) gold_fallback(_("out of patch space (PLT);" " relink with --incremental-full")); // The GOT and PLT entries have a 1-1 correspondance, so the GOT offset // can be calculated from the PLT index, adjusting for the three // reserved entries at the beginning of the GOT. plt_index = plt_offset / this->get_plt_entry_size() - 1; got_offset = (plt_index - offset + reserved) * 8; } gsym->set_plt_offset(plt_offset); // Every PLT entry needs a reloc. this->add_relocation(symtab, layout, gsym, 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. template<int size> unsigned int Output_data_plt_x86_64<size>::add_local_ifunc_entry( Symbol_table* symtab, Layout* layout, Sized_relobj_file<size, false>* relobj, unsigned int local_sym_index) { unsigned int plt_offset = this->irelative_count_ * this->get_plt_entry_size(); ++this->irelative_count_; section_offset_type got_offset = this->got_irelative_->current_data_size(); // Every PLT entry needs a GOT entry which points back to the PLT // entry. this->got_irelative_->set_current_data_size(got_offset + 8); // Every PLT entry needs a reloc. Reloc_section* rela = this->rela_irelative(symtab, layout); rela->add_symbolless_local_addend(relobj, local_sym_index, elfcpp::R_X86_64_IRELATIVE, this->got_irelative_, got_offset, 0); return plt_offset; } // Add the relocation for a PLT entry. template<int size> void Output_data_plt_x86_64<size>::add_relocation(Symbol_table* symtab, Layout* layout, Symbol* gsym, unsigned int got_offset) { if (gsym->type() == elfcpp::STT_GNU_IFUNC && gsym->can_use_relative_reloc(false)) { Reloc_section* rela = this->rela_irelative(symtab, layout); rela->add_symbolless_global_addend(gsym, elfcpp::R_X86_64_IRELATIVE, this->got_irelative_, got_offset, 0); } else { gsym->set_needs_dynsym_entry(); this->rel_->add_global(gsym, elfcpp::R_X86_64_JUMP_SLOT, this->got_plt_, got_offset, 0); } } // Return where the TLSDESC relocations should go, creating it if // necessary. These follow the JUMP_SLOT relocations. template<int size> typename Output_data_plt_x86_64<size>::Reloc_section* Output_data_plt_x86_64<size>::rela_tlsdesc(Layout* layout) { if (this->tlsdesc_rel_ == NULL) { this->tlsdesc_rel_ = new Reloc_section(false); layout->add_output_section_data(".rela.plt", elfcpp::SHT_RELA, elfcpp::SHF_ALLOC, this->tlsdesc_rel_, ORDER_DYNAMIC_PLT_RELOCS, false); gold_assert(this->tlsdesc_rel_->output_section() == this->rel_->output_section()); } return this->tlsdesc_rel_; } // Return where the IRELATIVE relocations should go in the PLT. These // follow the JUMP_SLOT and the TLSDESC relocations. template<int size> typename Output_data_plt_x86_64<size>::Reloc_section* Output_data_plt_x86_64<size>::rela_irelative(Symbol_table* symtab, Layout* layout) { if (this->irelative_rel_ == NULL) { // Make sure we have a place for the TLSDESC relocations, in // case we see any later on. this->rela_tlsdesc(layout); this->irelative_rel_ = new Reloc_section(false); layout->add_output_section_data(".rela.plt", elfcpp::SHT_RELA, elfcpp::SHF_ALLOC, this->irelative_rel_, ORDER_DYNAMIC_PLT_RELOCS, false); gold_assert(this->irelative_rel_->output_section() == this->rel_->output_section()); if (parameters->doing_static_link()) { // A statically linked executable will only have a .rela.plt // section to hold R_X86_64_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("__rela_iplt_start", NULL, Symbol_table::PREDEFINED, this->irelative_rel_, 0, 0, elfcpp::STT_NOTYPE, elfcpp::STB_GLOBAL, elfcpp::STV_HIDDEN, 0, false, true); symtab->define_in_output_data("__rela_iplt_end", NULL, Symbol_table::PREDEFINED, this->irelative_rel_, 0, 0, elfcpp::STT_NOTYPE, elfcpp::STB_GLOBAL, elfcpp::STV_HIDDEN, 0, true, true); } } return this->irelative_rel_; } // Return the PLT address to use for a global symbol. template<int size> uint64_t Output_data_plt_x86_64<size>::do_address_for_global(const Symbol* gsym) { uint64_t offset = 0; if (gsym->type() == elfcpp::STT_GNU_IFUNC && gsym->can_use_relative_reloc(false)) offset = (this->count_ + 1) * this->get_plt_entry_size(); return this->address() + offset + gsym->plt_offset(); } // Return the PLT address to use for a local symbol. These are always // IRELATIVE relocs. template<int size> uint64_t Output_data_plt_x86_64<size>::do_address_for_local(const Relobj* object, unsigned int r_sym) { return (this->address() + (this->count_ + 1) * this->get_plt_entry_size() + object->local_plt_offset(r_sym)); } // Set the final size. template<int size> void Output_data_plt_x86_64<size>::set_final_data_size() { // Number of regular and IFUNC PLT entries, plus the first entry. unsigned int count = this->count_ + this->irelative_count_ + 1; // Count the TLSDESC entry, if present. if (this->has_tlsdesc_entry()) ++count; this->set_data_size(count * this->get_plt_entry_size()); } // The first entry in the PLT for an executable. template<int size> const unsigned char Output_data_plt_x86_64_standard<size>::first_plt_entry[plt_entry_size] = { // From AMD64 ABI Draft 0.98, page 76 0xff, 0x35, // pushq contents of memory address 0, 0, 0, 0, // replaced with address of .got + 8 0xff, 0x25, // jmp indirect 0, 0, 0, 0, // replaced with address of .got + 16 0x90, 0x90, 0x90, 0x90 // noop (x4) }; template<int size> void Output_data_plt_x86_64_standard<size>::do_fill_first_plt_entry( unsigned char* pov, typename elfcpp::Elf_types<size>::Elf_Addr got_address, typename elfcpp::Elf_types<size>::Elf_Addr plt_address) { memcpy(pov, first_plt_entry, plt_entry_size); // We do a jmp relative to the PC at the end of this instruction. elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, (got_address + 8 - (plt_address + 6))); elfcpp::Swap<32, false>::writeval(pov + 8, (got_address + 16 - (plt_address + 12))); } // Subsequent entries in the PLT for an executable. template<int size> const unsigned char Output_data_plt_x86_64_standard<size>::plt_entry[plt_entry_size] = { // From AMD64 ABI Draft 0.98, page 76 0xff, 0x25, // jmpq indirect 0, 0, 0, 0, // replaced with address of symbol in .got 0x68, // pushq immediate 0, 0, 0, 0, // replaced with offset into relocation table 0xe9, // jmpq relative 0, 0, 0, 0 // replaced with offset to start of .plt }; template<int size> unsigned int Output_data_plt_x86_64_standard<size>::do_fill_plt_entry( unsigned char* pov, typename elfcpp::Elf_types<size>::Elf_Addr got_address, typename elfcpp::Elf_types<size>::Elf_Addr plt_address, unsigned int got_offset, unsigned int plt_offset, unsigned int plt_index) { // Check PC-relative offset overflow in PLT entry. uint64_t plt_got_pcrel_offset = (got_address + got_offset - (plt_address + plt_offset + 6)); if (Bits<32>::has_overflow(plt_got_pcrel_offset)) gold_error(_("PC-relative offset overflow in PLT entry %d"), plt_index + 1); memcpy(pov, plt_entry, plt_entry_size); elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, plt_got_pcrel_offset); elfcpp::Swap_unaligned<32, false>::writeval(pov + 7, plt_index); elfcpp::Swap<32, false>::writeval(pov + 12, - (plt_offset + plt_entry_size)); return 6; } // The reserved TLSDESC entry in the PLT for an executable. template<int size> const unsigned char Output_data_plt_x86_64_standard<size>::tlsdesc_plt_entry[plt_entry_size] = { // From Alexandre Oliva, "Thread-Local Storage Descriptors for IA32 // and AMD64/EM64T", Version 0.9.4 (2005-10-10). 0xff, 0x35, // pushq x(%rip) 0, 0, 0, 0, // replaced with address of linkmap GOT entry (at PLTGOT + 8) 0xff, 0x25, // jmpq *y(%rip) 0, 0, 0, 0, // replaced with offset of reserved TLSDESC_GOT entry 0x0f, 0x1f, // nop 0x40, 0 }; template<int size> void Output_data_plt_x86_64_standard<size>::do_fill_tlsdesc_entry( unsigned char* pov, typename elfcpp::Elf_types<size>::Elf_Addr got_address, typename elfcpp::Elf_types<size>::Elf_Addr plt_address, typename elfcpp::Elf_types<size>::Elf_Addr got_base, unsigned int tlsdesc_got_offset, unsigned int plt_offset) { memcpy(pov, tlsdesc_plt_entry, plt_entry_size); elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, (got_address + 8 - (plt_address + plt_offset + 6))); elfcpp::Swap_unaligned<32, false>::writeval(pov + 8, (got_base + tlsdesc_got_offset - (plt_address + plt_offset + 12))); } // Return the APLT address to use for a global symbol (for -z bndplt). uint64_t Output_data_plt_x86_64_bnd::do_address_for_global(const Symbol* gsym) { uint64_t offset = this->aplt_offset_; // Convert the PLT offset into an APLT offset. unsigned int plt_offset = gsym->plt_offset(); if (gsym->type() == elfcpp::STT_GNU_IFUNC && gsym->can_use_relative_reloc(false)) offset += this->regular_count() * aplt_entry_size; else plt_offset -= plt_entry_size; plt_offset = plt_offset / (plt_entry_size / aplt_entry_size); return this->address() + offset + plt_offset; } // Return the PLT address to use for a local symbol. These are always // IRELATIVE relocs. uint64_t Output_data_plt_x86_64_bnd::do_address_for_local(const Relobj* object, unsigned int r_sym) { // Convert the PLT offset into an APLT offset. unsigned int plt_offset = ((object->local_plt_offset(r_sym) - plt_entry_size) / (plt_entry_size / aplt_entry_size)); return (this->address() + this->aplt_offset_ + this->regular_count() * aplt_entry_size + plt_offset); } // Set the final size. void Output_data_plt_x86_64_bnd::set_final_data_size() { // Number of regular and IFUNC PLT entries. unsigned int count = this->entry_count(); // Count the first entry and the TLSDESC entry, if present. unsigned int extra = this->has_tlsdesc_entry() ? 2 : 1; unsigned int plt_size = (count + extra) * plt_entry_size; // Offset of the APLT. this->aplt_offset_ = plt_size; // Size of the APLT. plt_size += count * aplt_entry_size; this->set_data_size(plt_size); } // The first entry in the BND PLT. const unsigned char Output_data_plt_x86_64_bnd::first_plt_entry[plt_entry_size] = { // From AMD64 ABI Draft 0.98, page 76 0xff, 0x35, // pushq contents of memory address 0, 0, 0, 0, // replaced with address of .got + 8 0xf2, 0xff, 0x25, // bnd jmp indirect 0, 0, 0, 0, // replaced with address of .got + 16 0x0f, 0x1f, 0x00 // nop }; void Output_data_plt_x86_64_bnd::do_fill_first_plt_entry( unsigned char* pov, elfcpp::Elf_types<64>::Elf_Addr got_address, elfcpp::Elf_types<64>::Elf_Addr plt_address) { memcpy(pov, first_plt_entry, plt_entry_size); // We do a jmp relative to the PC at the end of this instruction. elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, (got_address + 8 - (plt_address + 6))); elfcpp::Swap<32, false>::writeval(pov + 9, (got_address + 16 - (plt_address + 13))); } // Subsequent entries in the BND PLT. const unsigned char Output_data_plt_x86_64_bnd::plt_entry[plt_entry_size] = { // From AMD64 ABI Draft 0.99.8, page 139 0x68, // pushq immediate 0, 0, 0, 0, // replaced with offset into relocation table 0xf2, 0xe9, // bnd jmpq relative 0, 0, 0, 0, // replaced with offset to start of .plt 0x0f, 0x1f, 0x44, 0, 0 // nop }; // Entries in the BND Additional PLT. const unsigned char Output_data_plt_x86_64_bnd::aplt_entry[aplt_entry_size] = { // From AMD64 ABI Draft 0.99.8, page 139 0xf2, 0xff, 0x25, // bnd jmpq indirect 0, 0, 0, 0, // replaced with address of symbol in .got 0x90, // nop }; unsigned int Output_data_plt_x86_64_bnd::do_fill_plt_entry( unsigned char* pov, elfcpp::Elf_types<64>::Elf_Addr, elfcpp::Elf_types<64>::Elf_Addr, unsigned int, unsigned int plt_offset, unsigned int plt_index) { memcpy(pov, plt_entry, plt_entry_size); elfcpp::Swap_unaligned<32, false>::writeval(pov + 1, plt_index); elfcpp::Swap<32, false>::writeval(pov + 7, -(plt_offset + 11)); return 0; } void Output_data_plt_x86_64_bnd::fill_aplt_entry( unsigned char* pov, elfcpp::Elf_types<64>::Elf_Addr got_address, elfcpp::Elf_types<64>::Elf_Addr plt_address, unsigned int got_offset, unsigned int plt_offset, unsigned int plt_index) { // Check PC-relative offset overflow in PLT entry. uint64_t plt_got_pcrel_offset = (got_address + got_offset - (plt_address + plt_offset + 7)); if (Bits<32>::has_overflow(plt_got_pcrel_offset)) gold_error(_("PC-relative offset overflow in APLT entry %d"), plt_index + 1); memcpy(pov, aplt_entry, aplt_entry_size); elfcpp::Swap_unaligned<32, false>::writeval(pov + 3, plt_got_pcrel_offset); } // The reserved TLSDESC entry in the PLT for an executable. const unsigned char Output_data_plt_x86_64_bnd::tlsdesc_plt_entry[plt_entry_size] = { // From Alexandre Oliva, "Thread-Local Storage Descriptors for IA32 // and AMD64/EM64T", Version 0.9.4 (2005-10-10). 0xff, 0x35, // pushq x(%rip) 0, 0, 0, 0, // replaced with address of linkmap GOT entry (at PLTGOT + 8) 0xf2, 0xff, 0x25, // jmpq *y(%rip) 0, 0, 0, 0, // replaced with offset of reserved TLSDESC_GOT entry 0x0f, 0x1f, 0 // nop }; void Output_data_plt_x86_64_bnd::do_fill_tlsdesc_entry( unsigned char* pov, elfcpp::Elf_types<64>::Elf_Addr got_address, elfcpp::Elf_types<64>::Elf_Addr plt_address, elfcpp::Elf_types<64>::Elf_Addr got_base, unsigned int tlsdesc_got_offset, unsigned int plt_offset) { memcpy(pov, tlsdesc_plt_entry, plt_entry_size); elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, (got_address + 8 - (plt_address + plt_offset + 6))); elfcpp::Swap_unaligned<32, false>::writeval(pov + 9, (got_base + tlsdesc_got_offset - (plt_address + plt_offset + 13))); } // Return the APLT address to use for a global symbol (for IBT). template<int size> uint64_t Output_data_plt_x86_64_ibt<size>::do_address_for_global(const Symbol* gsym) { uint64_t offset = this->aplt_offset_; // Convert the PLT offset into an APLT offset. unsigned int plt_offset = gsym->plt_offset(); if (gsym->type() == elfcpp::STT_GNU_IFUNC && gsym->can_use_relative_reloc(false)) offset += this->regular_count() * aplt_entry_size; else plt_offset -= plt_entry_size; plt_offset = plt_offset / (plt_entry_size / aplt_entry_size); return this->address() + offset + plt_offset; } // Return the PLT address to use for a local symbol. These are always // IRELATIVE relocs. template<int size> uint64_t Output_data_plt_x86_64_ibt<size>::do_address_for_local(const Relobj* object, unsigned int r_sym) { // Convert the PLT offset into an APLT offset. unsigned int plt_offset = ((object->local_plt_offset(r_sym) - plt_entry_size) / (plt_entry_size / aplt_entry_size)); return (this->address() + this->aplt_offset_ + this->regular_count() * aplt_entry_size + plt_offset); } // Set the final size. template<int size> void Output_data_plt_x86_64_ibt<size>::set_final_data_size() { // Number of regular and IFUNC PLT entries. unsigned int count = this->entry_count(); // Count the first entry and the TLSDESC entry, if present. unsigned int extra = this->has_tlsdesc_entry() ? 2 : 1; unsigned int plt_size = (count + extra) * plt_entry_size; // Offset of the APLT. this->aplt_offset_ = plt_size; // Size of the APLT. plt_size += count * aplt_entry_size; this->set_data_size(plt_size); } // The first entry in the IBT PLT. template<> const unsigned char Output_data_plt_x86_64_ibt<32>::first_plt_entry[plt_entry_size] = { // MPX isn't supported for x32, so we don't need the BND prefix. // From AMD64 ABI Draft 0.98, page 76 0xff, 0x35, // pushq contents of memory address 0, 0, 0, 0, // replaced with address of .got + 8 0xff, 0x25, // jmp indirect 0, 0, 0, 0, // replaced with address of .got + 16 0x90, 0x90, 0x90, 0x90 // noop (x4) }; template<> const unsigned char Output_data_plt_x86_64_ibt<64>::first_plt_entry[plt_entry_size] = { // Use the BND prefix so that IBT is compatible with MPX. 0xff, 0x35, // pushq contents of memory address 0, 0, 0, 0, // replaced with address of .got + 8 0xf2, 0xff, 0x25, // bnd jmp indirect 0, 0, 0, 0, // replaced with address of .got + 16 0x0f, 0x1f, 0x00 // nop }; template<int size> void Output_data_plt_x86_64_ibt<size>::do_fill_first_plt_entry( unsigned char* pov, typename elfcpp::Elf_types<size>::Elf_Addr got_address, typename elfcpp::Elf_types<size>::Elf_Addr plt_address) { // Offsets to the addresses needing relocation. const unsigned int roff1 = 2; const unsigned int roff2 = (size == 32) ? 8 : 9; memcpy(pov, first_plt_entry, plt_entry_size); // We do a jmp relative to the PC at the end of this instruction. elfcpp::Swap_unaligned<32, false>::writeval(pov + roff1, (got_address + 8 - (plt_address + roff1 + 4))); elfcpp::Swap<32, false>::writeval(pov + roff2, (got_address + 16 - (plt_address + roff2 + 4))); } // Subsequent entries in the IBT PLT. template<> const unsigned char Output_data_plt_x86_64_ibt<32>::plt_entry[plt_entry_size] = { // From AMD64 ABI Draft 1.0-rc1, Chapter 13. 0xf3, 0x0f, 0x1e, 0xfa, // endbr64 0x68, // pushq immediate 0, 0, 0, 0, // replaced with offset into relocation table 0xe9, // jmpq relative 0, 0, 0, 0, // replaced with offset to start of .plt 0x90, 0x90 // nop }; template<> const unsigned char Output_data_plt_x86_64_ibt<64>::plt_entry[plt_entry_size] = { // From AMD64 ABI Draft 1.0-rc1, Chapter 13. 0xf3, 0x0f, 0x1e, 0xfa, // endbr64 0x68, // pushq immediate 0, 0, 0, 0, // replaced with offset into relocation table 0xf2, 0xe9, // bnd jmpq relative 0, 0, 0, 0, // replaced with offset to start of .plt 0x90 // nop }; // Entries in the IBT Additional PLT. template<> const unsigned char Output_data_plt_x86_64_ibt<32>::aplt_entry[aplt_entry_size] = { // From AMD64 ABI Draft 1.0-rc1, Chapter 13. 0xf3, 0x0f, 0x1e, 0xfa, // endbr64 0xff, 0x25, // jmpq indirect 0, 0, 0, 0, // replaced with address of symbol in .got 0x0f, 0x1f, 0x04, 0x00, // nop 0x90, 0x90 // nop }; template<> const unsigned char Output_data_plt_x86_64_ibt<64>::aplt_entry[aplt_entry_size] = { // From AMD64 ABI Draft 1.0-rc1, Chapter 13. 0xf3, 0x0f, 0x1e, 0xfa, // endbr64 0xf2, 0xff, 0x25, // bnd jmpq indirect 0, 0, 0, 0, // replaced with address of symbol in .got 0x0f, 0x1f, 0x04, 0x00, // nop 0x90, // nop }; template<int size> unsigned int Output_data_plt_x86_64_ibt<size>::do_fill_plt_entry( unsigned char* pov, typename elfcpp::Elf_types<size>::Elf_Addr, typename elfcpp::Elf_types<size>::Elf_Addr, unsigned int, unsigned int plt_offset, unsigned int plt_index) { // Offsets to the addresses needing relocation. const unsigned int roff1 = 5; const unsigned int roff2 = (size == 32) ? 10 : 11; memcpy(pov, plt_entry, plt_entry_size); elfcpp::Swap_unaligned<32, false>::writeval(pov + roff1, plt_index); elfcpp::Swap<32, false>::writeval(pov + roff2, -(plt_offset + roff2 + 4)); return 0; } template<int size> void Output_data_plt_x86_64_ibt<size>::fill_aplt_entry( unsigned char* pov, typename elfcpp::Elf_types<size>::Elf_Addr got_address, typename elfcpp::Elf_types<size>::Elf_Addr plt_address, unsigned int got_offset, unsigned int plt_offset, unsigned int plt_index) { // Offset to the address needing relocation. const unsigned int roff = (size == 32) ? 6 : 7; // Check PC-relative offset overflow in PLT entry. uint64_t plt_got_pcrel_offset = (got_address + got_offset - (plt_address + plt_offset + roff + 4)); if (Bits<32>::has_overflow(plt_got_pcrel_offset)) gold_error(_("PC-relative offset overflow in APLT entry %d"), plt_index + 1); memcpy(pov, aplt_entry, aplt_entry_size); elfcpp::Swap_unaligned<32, false>::writeval(pov + roff, plt_got_pcrel_offset); } // The reserved TLSDESC entry in the IBT PLT for an executable. template<int size> const unsigned char Output_data_plt_x86_64_ibt<size>::tlsdesc_plt_entry[plt_entry_size] = { // From Alexandre Oliva, "Thread-Local Storage Descriptors for IA32 // and AMD64/EM64T", Version 0.9.4 (2005-10-10). 0xff, 0x35, // pushq x(%rip) 0, 0, 0, 0, // replaced with address of linkmap GOT entry (at PLTGOT + 8) 0xf2, 0xff, 0x25, // jmpq *y(%rip) 0, 0, 0, 0, // replaced with offset of reserved TLSDESC_GOT entry 0x0f, 0x1f, 0 // nop }; template<int size> void Output_data_plt_x86_64_ibt<size>::do_fill_tlsdesc_entry( unsigned char* pov, typename elfcpp::Elf_types<size>::Elf_Addr got_address, typename elfcpp::Elf_types<size>::Elf_Addr plt_address, typename elfcpp::Elf_types<size>::Elf_Addr got_base, unsigned int tlsdesc_got_offset, unsigned int plt_offset) { memcpy(pov, tlsdesc_plt_entry, plt_entry_size); elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, (got_address + 8 - (plt_address + plt_offset + 6))); elfcpp::Swap_unaligned<32, false>::writeval(pov + 9, (got_base + tlsdesc_got_offset - (plt_address + plt_offset + 13))); } // The .eh_frame unwind information for the PLT. template<int size> const unsigned char Output_data_plt_x86_64<size>::plt_eh_frame_cie[plt_eh_frame_cie_size] = { 1, // CIE version. 'z', // Augmentation: augmentation size included. 'R', // Augmentation: FDE encoding included. '\0', // End of augmentation string. 1, // Code alignment factor. 0x78, // Data alignment factor. 16, // Return address column. 1, // Augmentation size. (elfcpp::DW_EH_PE_pcrel // FDE encoding. | elfcpp::DW_EH_PE_sdata4), elfcpp::DW_CFA_def_cfa, 7, 8, // DW_CFA_def_cfa: r7 (rsp) ofs 8. elfcpp::DW_CFA_offset + 16, 1,// DW_CFA_offset: r16 (rip) at cfa-8. elfcpp::DW_CFA_nop, // Align to 16 bytes. elfcpp::DW_CFA_nop }; template<int size> const unsigned char Output_data_plt_x86_64_standard<size>::plt_eh_frame_fde[plt_eh_frame_fde_size] = { 0, 0, 0, 0, // Replaced with offset to .plt. 0, 0, 0, 0, // Replaced with size of .plt. 0, // Augmentation size. elfcpp::DW_CFA_def_cfa_offset, 16, // DW_CFA_def_cfa_offset: 16. elfcpp::DW_CFA_advance_loc + 6, // Advance 6 to __PLT__ + 6. elfcpp::DW_CFA_def_cfa_offset, 24, // DW_CFA_def_cfa_offset: 24. elfcpp::DW_CFA_advance_loc + 10, // Advance 10 to __PLT__ + 16. elfcpp::DW_CFA_def_cfa_expression, // DW_CFA_def_cfa_expression. 11, // Block length. elfcpp::DW_OP_breg7, 8, // Push %rsp + 8. elfcpp::DW_OP_breg16, 0, // Push %rip. elfcpp::DW_OP_lit15, // Push 0xf. elfcpp::DW_OP_and, // & (%rip & 0xf). elfcpp::DW_OP_lit11, // Push 0xb. elfcpp::DW_OP_ge, // >= ((%rip & 0xf) >= 0xb) elfcpp::DW_OP_lit3, // Push 3. elfcpp::DW_OP_shl, // << (((%rip & 0xf) >= 0xb) << 3) elfcpp::DW_OP_plus, // + ((((%rip&0xf)>=0xb)<<3)+%rsp+8 elfcpp::DW_CFA_nop, // Align to 32 bytes. elfcpp::DW_CFA_nop, elfcpp::DW_CFA_nop, elfcpp::DW_CFA_nop }; // The .eh_frame unwind information for the BND PLT. const unsigned char Output_data_plt_x86_64_bnd::plt_eh_frame_fde[plt_eh_frame_fde_size] = { 0, 0, 0, 0, // Replaced with offset to .plt. 0, 0, 0, 0, // Replaced with size of .plt. 0, // Augmentation size. elfcpp::DW_CFA_def_cfa_offset, 16, // DW_CFA_def_cfa_offset: 16. elfcpp::DW_CFA_advance_loc + 6, // Advance 6 to __PLT__ + 6. elfcpp::DW_CFA_def_cfa_offset, 24, // DW_CFA_def_cfa_offset: 24. elfcpp::DW_CFA_advance_loc + 10, // Advance 10 to __PLT__ + 16. elfcpp::DW_CFA_def_cfa_expression, // DW_CFA_def_cfa_expression. 11, // Block length. elfcpp::DW_OP_breg7, 8, // Push %rsp + 8. elfcpp::DW_OP_breg16, 0, // Push %rip. elfcpp::DW_OP_lit15, // Push 0xf. elfcpp::DW_OP_and, // & (%rip & 0xf). elfcpp::DW_OP_lit5, // Push 5. elfcpp::DW_OP_ge, // >= ((%rip & 0xf) >= 5) elfcpp::DW_OP_lit3, // Push 3. elfcpp::DW_OP_shl, // << (((%rip & 0xf) >= 5) << 3) elfcpp::DW_OP_plus, // + ((((%rip&0xf)>=5)<<3)+%rsp+8 elfcpp::DW_CFA_nop, // Align to 32 bytes. elfcpp::DW_CFA_nop, elfcpp::DW_CFA_nop, elfcpp::DW_CFA_nop }; // The .eh_frame unwind information for the BND PLT. template<int size> const unsigned char Output_data_plt_x86_64_ibt<size>::plt_eh_frame_fde[plt_eh_frame_fde_size] = { 0, 0, 0, 0, // Replaced with offset to .plt. 0, 0, 0, 0, // Replaced with size of .plt. 0, // Augmentation size. elfcpp::DW_CFA_def_cfa_offset, 16, // DW_CFA_def_cfa_offset: 16. elfcpp::DW_CFA_advance_loc + 6, // Advance 6 to __PLT__ + 6. elfcpp::DW_CFA_def_cfa_offset, 24, // DW_CFA_def_cfa_offset: 24. elfcpp::DW_CFA_advance_loc + 10, // Advance 10 to __PLT__ + 16. elfcpp::DW_CFA_def_cfa_expression, // DW_CFA_def_cfa_expression. 11, // Block length. elfcpp::DW_OP_breg7, 8, // Push %rsp + 8. elfcpp::DW_OP_breg16, 0, // Push %rip. elfcpp::DW_OP_lit15, // Push 0xf. elfcpp::DW_OP_and, // & (%rip & 0xf). elfcpp::DW_OP_lit9, // Push 9. elfcpp::DW_OP_ge, // >= ((%rip & 0xf) >= 9) elfcpp::DW_OP_lit3, // Push 3. elfcpp::DW_OP_shl, // << (((%rip & 0xf) >= 9) << 3) elfcpp::DW_OP_plus, // + ((((%rip&0xf)>=9)<<3)+%rsp+8 elfcpp::DW_CFA_nop, // Align to 32 bytes. elfcpp::DW_CFA_nop, elfcpp::DW_CFA_nop, elfcpp::DW_CFA_nop }; // Write out the PLT. This uses the hand-coded instructions above, // and adjusts them as needed. This is specified by the AMD64 ABI. template<int size> void Output_data_plt_x86_64<size>::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(); gold_assert(parameters->incremental_update() || (got_file_offset + this->got_plt_->data_size() == this->got_irelative_->offset())); const section_size_type got_size = convert_to_section_size_type(this->got_plt_->data_size() + this->got_irelative_->data_size()); unsigned char* const got_view = of->get_output_view(got_file_offset, got_size); unsigned char* pov = oview; // The base address of the .plt section. typename elfcpp::Elf_types<size>::Elf_Addr plt_address = this->address(); // The base address of the .got section. typename elfcpp::Elf_types<size>::Elf_Addr got_base = this->got_->address(); // The base address of the PLT portion of the .got section, // which is where the GOT pointer will point, and where the // three reserved GOT entries are located. typename elfcpp::Elf_types<size>::Elf_Addr got_address = this->got_plt_->address(); this->fill_first_plt_entry(pov, got_address, plt_address); pov += this->get_plt_entry_size(); // The first three entries in the GOT are reserved, and are written // by Output_data_got_plt_x86_64::do_write. unsigned char* got_pov = got_view + 24; unsigned int plt_offset = this->get_plt_entry_size(); unsigned int got_offset = 24; const unsigned int count = this->count_ + this->irelative_count_; for (unsigned int plt_index = 0; plt_index < count; ++plt_index, pov += this->get_plt_entry_size(), got_pov += 8, plt_offset += this->get_plt_entry_size(), got_offset += 8) { // Set and adjust the PLT entry itself. unsigned int lazy_offset = this->fill_plt_entry(pov, got_address, plt_address, got_offset, plt_offset, plt_index); // Set the entry in the GOT. elfcpp::Swap<64, false>::writeval(got_pov, plt_address + plt_offset + lazy_offset); } if (this->has_tlsdesc_entry()) { // Set and adjust the reserved TLSDESC PLT entry. unsigned int tlsdesc_got_offset = this->get_tlsdesc_got_offset(); this->fill_tlsdesc_entry(pov, got_address, plt_address, got_base, tlsdesc_got_offset, plt_offset); pov += this->get_plt_entry_size(); } 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); } // Write out the BND PLT. void Output_data_plt_x86_64_bnd::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); Output_data_got<64, false>* got = this->got(); Output_data_got_plt_x86_64* got_plt = this->got_plt(); Output_data_space* got_irelative = this->got_irelative(); const off_t got_file_offset = got_plt->offset(); gold_assert(parameters->incremental_update() || (got_file_offset + got_plt->data_size() == got_irelative->offset())); const section_size_type got_size = convert_to_section_size_type(got_plt->data_size() + got_irelative->data_size()); unsigned char* const got_view = of->get_output_view(got_file_offset, got_size); unsigned char* pov = oview; // The base address of the .plt section. elfcpp::Elf_types<64>::Elf_Addr plt_address = this->address(); // The base address of the .got section. elfcpp::Elf_types<64>::Elf_Addr got_base = got->address(); // The base address of the PLT portion of the .got section, // which is where the GOT pointer will point, and where the // three reserved GOT entries are located. elfcpp::Elf_types<64>::Elf_Addr got_address = got_plt->address(); this->fill_first_plt_entry(pov, got_address, plt_address); pov += plt_entry_size; // The first three entries in the GOT are reserved, and are written // by Output_data_got_plt_x86_64::do_write. unsigned char* got_pov = got_view + 24; unsigned int plt_offset = plt_entry_size; unsigned int got_offset = 24; const unsigned int count = this->entry_count(); for (unsigned int plt_index = 0; plt_index < count; ++plt_index, pov += plt_entry_size, got_pov += 8, plt_offset += plt_entry_size, got_offset += 8) { // Set and adjust the PLT entry itself. unsigned int lazy_offset = this->fill_plt_entry(pov, got_address, plt_address, got_offset, plt_offset, plt_index); // Set the entry in the GOT. elfcpp::Swap<64, false>::writeval(got_pov, plt_address + plt_offset + lazy_offset); } if (this->has_tlsdesc_entry()) { // Set and adjust the reserved TLSDESC PLT entry. unsigned int tlsdesc_got_offset = this->get_tlsdesc_got_offset(); this->fill_tlsdesc_entry(pov, got_address, plt_address, got_base, tlsdesc_got_offset, plt_offset); pov += this->get_plt_entry_size(); } // Write the additional PLT. got_offset = 24; for (unsigned int plt_index = 0; plt_index < count; ++plt_index, pov += aplt_entry_size, plt_offset += aplt_entry_size, got_offset += 8) { // Set and adjust the APLT entry. this->fill_aplt_entry(pov, got_address, plt_address, got_offset, plt_offset, plt_index); } 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); } // Write out the IBT PLT. template<int size> void Output_data_plt_x86_64_ibt<size>::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); Output_data_got<64, false>* got = this->got(); Output_data_got_plt_x86_64* got_plt = this->got_plt(); Output_data_space* got_irelative = this->got_irelative(); const off_t got_file_offset = got_plt->offset(); gold_assert(parameters->incremental_update() || (got_file_offset + got_plt->data_size() == got_irelative->offset())); const section_size_type got_size = convert_to_section_size_type(got_plt->data_size() + got_irelative->data_size()); unsigned char* const got_view = of->get_output_view(got_file_offset, got_size); unsigned char* pov = oview; // The base address of the .plt section. elfcpp::Elf_types<64>::Elf_Addr plt_address = this->address(); // The base address of the .got section. elfcpp::Elf_types<64>::Elf_Addr got_base = got->address(); // The base address of the PLT portion of the .got section, // which is where the GOT pointer will point, and where the // three reserved GOT entries are located. elfcpp::Elf_types<64>::Elf_Addr got_address = got_plt->address(); this->fill_first_plt_entry(pov, got_address, plt_address); pov += plt_entry_size; // The first three entries in the GOT are reserved, and are written // by Output_data_got_plt_x86_64::do_write. unsigned char* got_pov = got_view + 24; unsigned int plt_offset = plt_entry_size; unsigned int got_offset = 24; const unsigned int count = this->entry_count(); for (unsigned int plt_index = 0; plt_index < count; ++plt_index, pov += plt_entry_size, got_pov += 8, plt_offset += plt_entry_size, got_offset += 8) { // Set and adjust the PLT entry itself. unsigned int lazy_offset = this->fill_plt_entry(pov, got_address, plt_address, got_offset, plt_offset, plt_index); // Set the entry in the GOT. elfcpp::Swap<64, false>::writeval(got_pov, plt_address + plt_offset + lazy_offset); } if (this->has_tlsdesc_entry()) { // Set and adjust the reserved TLSDESC PLT entry. unsigned int tlsdesc_got_offset = this->get_tlsdesc_got_offset(); this->fill_tlsdesc_entry(pov, got_address, plt_address, got_base, tlsdesc_got_offset, plt_offset); pov += this->get_plt_entry_size(); } // Write the additional PLT. got_offset = 24; for (unsigned int plt_index = 0; plt_index < count; ++plt_index, pov += aplt_entry_size, plt_offset += aplt_entry_size, got_offset += 8) { // Set and adjust the APLT entry. this->fill_aplt_entry(pov, got_address, plt_address, got_offset, plt_offset, plt_index); } 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. template<int size> void Target_x86_64<size>::make_plt_section(Symbol_table* symtab, Layout* layout) { if (this->plt_ == NULL) { // Create the GOT sections first. this->got_section(symtab, layout); this->plt_ = this->make_data_plt(layout, this->got_, this->got_plt_, this->got_irelative_); // Add unwind information if requested. if (parameters->options().ld_generated_unwind_info()) this->plt_->add_eh_frame(layout); 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 .rela.plt point to .plt. Output_section* rela_plt_os = this->plt_->rela_plt()->output_section(); rela_plt_os->set_info_section(this->plt_->output_section()); } } template<> Output_data_plt_x86_64<32>* Target_x86_64<32>::do_make_data_plt(Layout* layout, Output_data_got<64, false>* got, Output_data_got_plt_x86_64* got_plt, Output_data_space* got_irelative) { if (this->feature_1_ & elfcpp::GNU_PROPERTY_X86_FEATURE_1_IBT) return new Output_data_plt_x86_64_ibt<32>(layout, got, got_plt, got_irelative); return new Output_data_plt_x86_64_standard<32>(layout, got, got_plt, got_irelative); } template<> Output_data_plt_x86_64<64>* Target_x86_64<64>::do_make_data_plt(Layout* layout, Output_data_got<64, false>* got, Output_data_got_plt_x86_64* got_plt, Output_data_space* got_irelative) { if (this->feature_1_ & elfcpp::GNU_PROPERTY_X86_FEATURE_1_IBT) return new Output_data_plt_x86_64_ibt<64>(layout, got, got_plt, got_irelative); else if (parameters->options().bndplt()) return new Output_data_plt_x86_64_bnd(layout, got, got_plt, got_irelative); else return new Output_data_plt_x86_64_standard<64>(layout, got, got_plt, got_irelative); } template<> Output_data_plt_x86_64<32>* Target_x86_64<32>::do_make_data_plt(Layout* layout, Output_data_got<64, false>* got, Output_data_got_plt_x86_64* got_plt, Output_data_space* got_irelative, unsigned int plt_count) { if (this->feature_1_ & elfcpp::GNU_PROPERTY_X86_FEATURE_1_IBT) return new Output_data_plt_x86_64_ibt<32>(layout, got, got_plt, got_irelative, plt_count); return new Output_data_plt_x86_64_standard<32>(layout, got, got_plt, got_irelative, plt_count); } template<> Output_data_plt_x86_64<64>* Target_x86_64<64>::do_make_data_plt(Layout* layout, Output_data_got<64, false>* got, Output_data_got_plt_x86_64* got_plt, Output_data_space* got_irelative, unsigned int plt_count) { if (this->feature_1_ & elfcpp::GNU_PROPERTY_X86_FEATURE_1_IBT) return new Output_data_plt_x86_64_ibt<64>(layout, got, got_plt, got_irelative, plt_count); else if (parameters->options().bndplt()) return new Output_data_plt_x86_64_bnd(layout, got, got_plt, got_irelative, plt_count); else return new Output_data_plt_x86_64_standard<64>(layout, got, got_plt, got_irelative, plt_count); } // Return the section for TLSDESC relocations. template<int size> typename Target_x86_64<size>::Reloc_section* Target_x86_64<size>::rela_tlsdesc_section(Layout* layout) const { return this->plt_section()->rela_tlsdesc(layout); } // Create a PLT entry for a global symbol. template<int size> void Target_x86_64<size>::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(symtab, layout, gsym); } // Make a PLT entry for a local STT_GNU_IFUNC symbol. template<int size> void Target_x86_64<size>::make_local_ifunc_plt_entry( Symbol_table* symtab, Layout* layout, Sized_relobj_file<size, 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(symtab, layout, relobj, local_sym_index); relobj->set_local_plt_offset(local_sym_index, plt_offset); } // Return the number of entries in the PLT. template<int size> unsigned int Target_x86_64<size>::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. template<int size> unsigned int Target_x86_64<size>::first_plt_entry_offset() const { if (this->plt_ == NULL) return 0; return this->plt_->first_plt_entry_offset(); } // Return the size of each PLT entry. template<int size> unsigned int Target_x86_64<size>::plt_entry_size() const { if (this->plt_ == NULL) return 0; return this->plt_->get_plt_entry_size(); } // Create the GOT and PLT sections for an incremental update. template<int size> Output_data_got_base* Target_x86_64<size>::init_got_plt_for_update(Symbol_table* symtab, Layout* layout, unsigned int got_count, unsigned int plt_count) { gold_assert(this->got_ == NULL); this->got_ = new Output_data_got<64, false>(got_count * 8); layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS, (elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE), this->got_, ORDER_RELRO_LAST, true); // Add the three reserved entries. this->got_plt_ = new Output_data_got_plt_x86_64(layout, (plt_count + 3) * 8); layout->add_output_section_data(".got.plt", elfcpp::SHT_PROGBITS, (elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE), this->got_plt_, ORDER_NON_RELRO_FIRST, false); // 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. // FIXME: Get the count for TLSDESC entries. this->got_tlsdesc_ = new Output_data_got<64, false>(0); layout->add_output_section_data(".got.plt", elfcpp::SHT_PROGBITS, elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE, this->got_tlsdesc_, ORDER_NON_RELRO_FIRST, false); // If there are any IRELATIVE relocations, they get GOT entries in // .got.plt after the jump slot and TLSDESC entries. this->got_irelative_ = new Output_data_space(0, 8, "** GOT IRELATIVE PLT"); layout->add_output_section_data(".got.plt", elfcpp::SHT_PROGBITS, elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE, this->got_irelative_, ORDER_NON_RELRO_FIRST, false); // Create the PLT section. this->plt_ = this->make_data_plt(layout, this->got_, this->got_plt_, this->got_irelative_, plt_count); // Add unwind information if requested. if (parameters->options().ld_generated_unwind_info()) this->plt_->add_eh_frame(layout); 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 .rela.plt point to .plt. Output_section* rela_plt_os = this->plt_->rela_plt()->output_section(); rela_plt_os->set_info_section(this->plt_->output_section()); // Create the rela_dyn section. this->rela_dyn_section(layout); return this->got_; } // Reserve a GOT entry for a local symbol, and regenerate any // necessary dynamic relocations. template<int size> void Target_x86_64<size>::reserve_local_got_entry( unsigned int got_index, Sized_relobj<size, false>* obj, unsigned int r_sym, unsigned int got_type) { unsigned int got_offset = got_index * 8; Reloc_section* rela_dyn = this->rela_dyn_section(NULL); this->got_->reserve_local(got_index, obj, r_sym, got_type); switch (got_type) { case GOT_TYPE_STANDARD: if (parameters->options().output_is_position_independent()) rela_dyn->add_local_relative(obj, r_sym, elfcpp::R_X86_64_RELATIVE, this->got_, got_offset, 0, false); break; case GOT_TYPE_TLS_OFFSET: rela_dyn->add_local(obj, r_sym, elfcpp::R_X86_64_TPOFF64, this->got_, got_offset, 0); break; case GOT_TYPE_TLS_PAIR: this->got_->reserve_slot(got_index + 1); rela_dyn->add_local(obj, r_sym, elfcpp::R_X86_64_DTPMOD64, this->got_, got_offset, 0); break; case GOT_TYPE_TLS_DESC: gold_fatal(_("TLS_DESC not yet supported for incremental linking")); // this->got_->reserve_slot(got_index + 1); // rela_dyn->add_target_specific(elfcpp::R_X86_64_TLSDESC, arg, // this->got_, got_offset, 0); break; default: gold_unreachable(); } } // Reserve a GOT entry for a global symbol, and regenerate any // necessary dynamic relocations. template<int size> void Target_x86_64<size>::reserve_global_got_entry(unsigned int got_index, Symbol* gsym, unsigned int got_type) { unsigned int got_offset = got_index * 8; Reloc_section* rela_dyn = this->rela_dyn_section(NULL); this->got_->reserve_global(got_index, gsym, got_type); switch (got_type) { case GOT_TYPE_STANDARD: if (!gsym->final_value_is_known()) { if (gsym->is_from_dynobj() || gsym->is_undefined() || gsym->is_preemptible() || gsym->type() == elfcpp::STT_GNU_IFUNC) rela_dyn->add_global(gsym, elfcpp::R_X86_64_GLOB_DAT, this->got_, got_offset, 0); else rela_dyn->add_global_relative(gsym, elfcpp::R_X86_64_RELATIVE, this->got_, got_offset, 0, false); } break; case GOT_TYPE_TLS_OFFSET: rela_dyn->add_global_relative(gsym, elfcpp::R_X86_64_TPOFF64, this->got_, got_offset, 0, false); break; case GOT_TYPE_TLS_PAIR: this->got_->reserve_slot(got_index + 1); rela_dyn->add_global_relative(gsym, elfcpp::R_X86_64_DTPMOD64, this->got_, got_offset, 0, false); rela_dyn->add_global_relative(gsym, elfcpp::R_X86_64_DTPOFF64, this->got_, got_offset + 8, 0, false); break; case GOT_TYPE_TLS_DESC: this->got_->reserve_slot(got_index + 1); rela_dyn->add_global_relative(gsym, elfcpp::R_X86_64_TLSDESC, this->got_, got_offset, 0, false); break; default: gold_unreachable(); } } // Register an existing PLT entry for a global symbol. template<int size> void Target_x86_64<size>::register_global_plt_entry(Symbol_table* symtab, Layout* layout, unsigned int plt_index, Symbol* gsym) { gold_assert(this->plt_ != NULL); gold_assert(!gsym->has_plt_offset()); this->plt_->reserve_slot(plt_index); gsym->set_plt_offset((plt_index + 1) * this->plt_entry_size()); unsigned int got_offset = (plt_index + 3) * 8; this->plt_->add_relocation(symtab, layout, gsym, got_offset); } // Force a COPY relocation for a given symbol. template<int size> void Target_x86_64<size>::emit_copy_reloc( Symbol_table* symtab, Symbol* sym, Output_section* os, off_t offset) { this->copy_relocs_.emit_copy_reloc(symtab, symtab->get_sized_symbol<size>(sym), os, offset, this->rela_dyn_section(NULL)); } // Define the _TLS_MODULE_BASE_ symbol in the TLS segment. template<int size> void Target_x86_64<size>::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 the reserved PLT and GOT entries for the TLS descriptor resolver. template<int size> void Target_x86_64<size>::reserve_tlsdesc_entries(Symbol_table* symtab, Layout* layout) { if (this->plt_ == NULL) this->make_plt_section(symtab, layout); if (!this->plt_->has_tlsdesc_entry()) { // Allocate the TLSDESC_GOT entry. Output_data_got<64, false>* got = this->got_section(symtab, layout); unsigned int got_offset = got->add_constant(0); // Allocate the TLSDESC_PLT entry. this->plt_->reserve_tlsdesc_entry(got_offset); } } // Create a GOT entry for the TLS module index. template<int size> unsigned int Target_x86_64<size>::got_mod_index_entry(Symbol_table* symtab, Layout* layout, Sized_relobj_file<size, false>* object) { if (this->got_mod_index_offset_ == -1U) { gold_assert(symtab != NULL && layout != NULL && object != NULL); Reloc_section* rela_dyn = this->rela_dyn_section(layout); Output_data_got<64, false>* got = this->got_section(symtab, layout); unsigned int got_offset = got->add_constant(0); rela_dyn->add_local(object, 0, elfcpp::R_X86_64_DTPMOD64, got, got_offset, 0); 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. template<int size> tls::Tls_optimization Target_x86_64<size>::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_X86_64_TLSGD: case elfcpp::R_X86_64_GOTPC32_TLSDESC: case elfcpp::R_X86_64_TLSDESC_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_X86_64_TLSLD: // 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_X86_64_DTPOFF32: case elfcpp::R_X86_64_DTPOFF64: // Another Local-Dynamic reloc. return tls::TLSOPT_TO_LE; case elfcpp::R_X86_64_GOTTPOFF: // 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_X86_64_TPOFF32: // 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. template<int size> int Target_x86_64<size>::Scan::get_reference_flags(unsigned int r_type) { switch (r_type) { case elfcpp::R_X86_64_NONE: case elfcpp::R_X86_64_GNU_VTINHERIT: case elfcpp::R_X86_64_GNU_VTENTRY: case elfcpp::R_X86_64_GOTPC32: case elfcpp::R_X86_64_GOTPC64: // No symbol reference. return 0; case elfcpp::R_X86_64_64: case elfcpp::R_X86_64_32: case elfcpp::R_X86_64_32S: case elfcpp::R_X86_64_16: case elfcpp::R_X86_64_8: return Symbol::ABSOLUTE_REF; case elfcpp::R_X86_64_PC64: case elfcpp::R_X86_64_PC32: case elfcpp::R_X86_64_PC32_BND: case elfcpp::R_X86_64_PC16: case elfcpp::R_X86_64_PC8: case elfcpp::R_X86_64_GOTOFF64: return Symbol::RELATIVE_REF; case elfcpp::R_X86_64_PLT32: case elfcpp::R_X86_64_PLT32_BND: case elfcpp::R_X86_64_PLTOFF64: return Symbol::FUNCTION_CALL | Symbol::RELATIVE_REF; case elfcpp::R_X86_64_GOT64: case elfcpp::R_X86_64_GOT32: case elfcpp::R_X86_64_GOTPCREL64: case elfcpp::R_X86_64_GOTPCREL: case elfcpp::R_X86_64_GOTPCRELX: case elfcpp::R_X86_64_REX_GOTPCRELX: case elfcpp::R_X86_64_GOTPLT64: // Absolute in GOT. return Symbol::ABSOLUTE_REF; case elfcpp::R_X86_64_TLSGD: // Global-dynamic case elfcpp::R_X86_64_GOTPC32_TLSDESC: // Global-dynamic (from ~oliva url) case elfcpp::R_X86_64_TLSDESC_CALL: case elfcpp::R_X86_64_TLSLD: // Local-dynamic case elfcpp::R_X86_64_DTPOFF32: case elfcpp::R_X86_64_DTPOFF64: case elfcpp::R_X86_64_GOTTPOFF: // Initial-exec case elfcpp::R_X86_64_TPOFF32: // Local-exec return Symbol::TLS_REF; case elfcpp::R_X86_64_COPY: case elfcpp::R_X86_64_GLOB_DAT: case elfcpp::R_X86_64_JUMP_SLOT: case elfcpp::R_X86_64_RELATIVE: case elfcpp::R_X86_64_IRELATIVE: case elfcpp::R_X86_64_TPOFF64: case elfcpp::R_X86_64_DTPMOD64: case elfcpp::R_X86_64_TLSDESC: case elfcpp::R_X86_64_SIZE32: case elfcpp::R_X86_64_SIZE64: default: // Not expected. We will give an error later. return 0; } } // Report an unsupported relocation against a local symbol. template<int size> void Target_x86_64<size>::Scan::unsupported_reloc_local( Sized_relobj_file<size, false>* object, unsigned int r_type) { gold_error(_("%s: unsupported reloc %u against local symbol"), object->name().c_str(), r_type); } // We are about to emit a dynamic relocation of type R_TYPE. If the // dynamic linker does not support it, issue an error. The GNU linker // only issues a non-PIC error for an allocated read-only section. // Here we know the section is allocated, but we don't know that it is // read-only. But we check for all the relocation types which the // glibc dynamic linker supports, so it seems appropriate to issue an // error even if the section is not read-only. If GSYM is not NULL, // it is the symbol the relocation is against; if it is NULL, the // relocation is against a local symbol. template<int size> void Target_x86_64<size>::Scan::check_non_pic(Relobj* object, unsigned int r_type, Symbol* gsym) { switch (r_type) { // These are the relocation types supported by glibc for x86_64 // which should always work. case elfcpp::R_X86_64_RELATIVE: case elfcpp::R_X86_64_IRELATIVE: case elfcpp::R_X86_64_GLOB_DAT: case elfcpp::R_X86_64_JUMP_SLOT: case elfcpp::R_X86_64_DTPMOD64: case elfcpp::R_X86_64_DTPOFF64: case elfcpp::R_X86_64_TPOFF64: case elfcpp::R_X86_64_64: case elfcpp::R_X86_64_COPY: return; // glibc supports these reloc types, but they can overflow. case elfcpp::R_X86_64_PC32: case elfcpp::R_X86_64_PC32_BND: // A PC relative reference is OK against a local symbol or if // the symbol is defined locally. if (gsym == NULL || (!gsym->is_from_dynobj() && !gsym->is_undefined() && !gsym->is_preemptible())) return; // Fall through. case elfcpp::R_X86_64_32: // R_X86_64_32 is OK for x32. if (size == 32 && r_type == elfcpp::R_X86_64_32) return; if (this->issued_non_pic_error_) return; gold_assert(parameters->options().output_is_position_independent()); if (gsym == NULL) object->error(_("requires dynamic R_X86_64_32 reloc which may " "overflow at runtime; recompile with -fPIC")); else { const char *r_name; switch (r_type) { case elfcpp::R_X86_64_32: r_name = "R_X86_64_32"; break; case elfcpp::R_X86_64_PC32: r_name = "R_X86_64_PC32"; break; case elfcpp::R_X86_64_PC32_BND: r_name = "R_X86_64_PC32_BND"; break; default: gold_unreachable(); break; } object->error(_("requires dynamic %s reloc against '%s' " "which may overflow at runtime; recompile " "with -fPIC"), r_name, gsym->name()); } this->issued_non_pic_error_ = true; return; default: // This prevents us from issuing more than one error per reloc // section. But we can still wind up issuing more than one // error per object file. if (this->issued_non_pic_error_) return; gold_assert(parameters->options().output_is_position_independent()); object->error(_("requires unsupported dynamic reloc %u; " "recompile with -fPIC"), r_type); this->issued_non_pic_error_ = true; return; case elfcpp::R_X86_64_NONE: gold_unreachable(); } } // Return whether we need to make a PLT entry for a relocation of the // given type against a STT_GNU_IFUNC symbol. template<int size> bool Target_x86_64<size>::Scan::reloc_needs_plt_for_ifunc( Sized_relobj_file<size, 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. template<int size> inline void Target_x86_64<size>::Scan::local(Symbol_table* symtab, Layout* layout, Target_x86_64<size>* target, Sized_relobj_file<size, false>* object, unsigned int data_shndx, Output_section* output_section, const elfcpp::Rela<size, false>& reloc, unsigned int r_type, const elfcpp::Sym<size, false>& lsym, bool is_discarded) { if (is_discarded) return; // A local STT_GNU_IFUNC symbol may require a PLT entry. bool is_ifunc = lsym.get_st_type() == elfcpp::STT_GNU_IFUNC; if (is_ifunc && this->reloc_needs_plt_for_ifunc(object, r_type)) { unsigned int r_sym = elfcpp::elf_r_sym<size>(reloc.get_r_info()); target->make_local_ifunc_plt_entry(symtab, layout, object, r_sym); } switch (r_type) { case elfcpp::R_X86_64_NONE: case elfcpp::R_X86_64_GNU_VTINHERIT: case elfcpp::R_X86_64_GNU_VTENTRY: break; case elfcpp::R_X86_64_64: // 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_X86_64_RELATIVE relocation so the dynamic loader can // relocate it easily. if (parameters->options().output_is_position_independent()) { unsigned int r_sym = elfcpp::elf_r_sym<size>(reloc.get_r_info()); Reloc_section* rela_dyn = target->rela_dyn_section(layout); rela_dyn->add_local_relative(object, r_sym, (size == 32 ? elfcpp::R_X86_64_RELATIVE64 : elfcpp::R_X86_64_RELATIVE), output_section, data_shndx, reloc.get_r_offset(), reloc.get_r_addend(), is_ifunc); } break; case elfcpp::R_X86_64_32: case elfcpp::R_X86_64_32S: case elfcpp::R_X86_64_16: case elfcpp::R_X86_64_8: // If building a shared library (or a position-independent // executable), we need to create a dynamic relocation for this // location. We can't use an R_X86_64_RELATIVE relocation // because that is always a 64-bit relocation. if (parameters->options().output_is_position_independent()) { // Use R_X86_64_RELATIVE relocation for R_X86_64_32 under x32. if (size == 32 && r_type == elfcpp::R_X86_64_32) { unsigned int r_sym = elfcpp::elf_r_sym<size>(reloc.get_r_info()); Reloc_section* rela_dyn = target->rela_dyn_section(layout); rela_dyn->add_local_relative(object, r_sym, elfcpp::R_X86_64_RELATIVE, output_section, data_shndx, reloc.get_r_offset(), reloc.get_r_addend(), is_ifunc); break; } this->check_non_pic(object, r_type, NULL); Reloc_section* rela_dyn = target->rela_dyn_section(layout); unsigned int r_sym = elfcpp::elf_r_sym<size>(reloc.get_r_info()); if (lsym.get_st_type() != elfcpp::STT_SECTION) rela_dyn->add_local(object, r_sym, r_type, output_section, data_shndx, reloc.get_r_offset(), reloc.get_r_addend()); 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 rela_dyn->add_local_section(object, shndx, r_type, output_section, data_shndx, reloc.get_r_offset(), reloc.get_r_addend()); } } break; case elfcpp::R_X86_64_PC64: case elfcpp::R_X86_64_PC32: case elfcpp::R_X86_64_PC32_BND: case elfcpp::R_X86_64_PC16: case elfcpp::R_X86_64_PC8: break; case elfcpp::R_X86_64_PLT32: case elfcpp::R_X86_64_PLT32_BND: // Since we know this is a local symbol, we can handle this as a // PC32 reloc. break; case elfcpp::R_X86_64_GOTPC32: case elfcpp::R_X86_64_GOTOFF64: case elfcpp::R_X86_64_GOTPC64: case elfcpp::R_X86_64_PLTOFF64: // We need a GOT section. target->got_section(symtab, layout); // For PLTOFF64, we'd normally want a PLT section, but since we // know this is a local symbol, no PLT is needed. break; case elfcpp::R_X86_64_GOT64: case elfcpp::R_X86_64_GOT32: case elfcpp::R_X86_64_GOTPCREL64: case elfcpp::R_X86_64_GOTPCREL: case elfcpp::R_X86_64_GOTPCRELX: case elfcpp::R_X86_64_REX_GOTPCRELX: case elfcpp::R_X86_64_GOTPLT64: { // The symbol requires a GOT section. Output_data_got<64, false>* got = target->got_section(symtab, layout); // If the relocation symbol isn't IFUNC, // and is local, then we will convert // mov foo@GOTPCREL(%rip), %reg // to lea foo(%rip), %reg. // in Relocate::relocate. if (!parameters->incremental() && (r_type == elfcpp::R_X86_64_GOTPCREL || r_type == elfcpp::R_X86_64_GOTPCRELX || r_type == elfcpp::R_X86_64_REX_GOTPCRELX) && reloc.get_r_offset() >= 2 && !is_ifunc) { section_size_type stype; const unsigned char* view = object->section_contents(data_shndx, &stype, true); if (view[reloc.get_r_offset() - 2] == 0x8b) break; } // The symbol requires a GOT entry. unsigned int r_sym = elfcpp::elf_r_sym<size>(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 (is_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 relocation for this symbol's GOT entry. if (parameters->options().output_is_position_independent()) { Reloc_section* rela_dyn = target->rela_dyn_section(layout); // R_X86_64_RELATIVE assumes a 64-bit relocation. if (r_type != elfcpp::R_X86_64_GOT32) { unsigned int got_offset = object->local_got_offset(r_sym, GOT_TYPE_STANDARD); rela_dyn->add_local_relative(object, r_sym, elfcpp::R_X86_64_RELATIVE, got, got_offset, 0, is_ifunc); } else { this->check_non_pic(object, r_type, NULL); gold_assert(lsym.get_st_type() != elfcpp::STT_SECTION); rela_dyn->add_local( object, r_sym, r_type, got, object->local_got_offset(r_sym, GOT_TYPE_STANDARD), 0); } } } // For GOTPLT64, we'd normally want a PLT section, but since // we know this is a local symbol, no PLT is needed. } break; case elfcpp::R_X86_64_COPY: case elfcpp::R_X86_64_GLOB_DAT: case elfcpp::R_X86_64_JUMP_SLOT: case elfcpp::R_X86_64_RELATIVE: case elfcpp::R_X86_64_IRELATIVE: // These are outstanding tls relocs, which are unexpected when linking case elfcpp::R_X86_64_TPOFF64: case elfcpp::R_X86_64_DTPMOD64: case elfcpp::R_X86_64_TLSDESC: 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_X86_64_TLSGD: // Global-dynamic case elfcpp::R_X86_64_GOTPC32_TLSDESC: // Global-dynamic (from ~oliva url) case elfcpp::R_X86_64_TLSDESC_CALL: case elfcpp::R_X86_64_TLSLD: // Local-dynamic case elfcpp::R_X86_64_DTPOFF32: case elfcpp::R_X86_64_DTPOFF64: case elfcpp::R_X86_64_GOTTPOFF: // Initial-exec case elfcpp::R_X86_64_TPOFF32: // Local-exec { bool output_is_shared = parameters->options().shared(); const tls::Tls_optimization optimized_type = Target_x86_64<size>::optimize_tls_reloc(!output_is_shared, r_type); switch (r_type) { case elfcpp::R_X86_64_TLSGD: // General-dynamic if (optimized_type == tls::TLSOPT_NONE) { // Create a pair of GOT entries for the module index and // dtv-relative offset. Output_data_got<64, false>* got = target->got_section(symtab, layout); unsigned int r_sym = elfcpp::elf_r_sym<size>(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->rela_dyn_section(layout), elfcpp::R_X86_64_DTPMOD64); } else if (optimized_type != tls::TLSOPT_TO_LE) unsupported_reloc_local(object, r_type); break; case elfcpp::R_X86_64_GOTPC32_TLSDESC: target->define_tls_base_symbol(symtab, layout); if (optimized_type == tls::TLSOPT_NONE) { // Create reserved PLT and GOT entries for the resolver. target->reserve_tlsdesc_entries(symtab, layout); // Generate a double GOT entry with an // R_X86_64_TLSDESC reloc. The R_X86_64_TLSDESC 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<64, false>* got = target->got_tlsdesc_section(); unsigned int r_sym = elfcpp::elf_r_sym<size>(reloc.get_r_info()); if (!object->local_has_got_offset(r_sym, GOT_TYPE_TLS_DESC)) { unsigned int got_offset = got->add_constant(0); got->add_constant(0); object->set_local_got_offset(r_sym, GOT_TYPE_TLS_DESC, got_offset); Reloc_section* rt = target->rela_tlsdesc_section(layout); // We store the arguments we need in a vector, and // use the index into the vector as the parameter // to pass to the target specific routines. uintptr_t intarg = target->add_tlsdesc_info(object, r_sym); void* arg = reinterpret_cast<void*>(intarg); rt->add_target_specific(elfcpp::R_X86_64_TLSDESC, arg, got, got_offset, 0); } } else if (optimized_type != tls::TLSOPT_TO_LE) unsupported_reloc_local(object, r_type); break; case elfcpp::R_X86_64_TLSDESC_CALL: break; case elfcpp::R_X86_64_TLSLD: // 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_X86_64_DTPOFF32: case elfcpp::R_X86_64_DTPOFF64: break; case elfcpp::R_X86_64_GOTTPOFF: // Initial-exec layout->set_has_static_tls(); if (optimized_type == tls::TLSOPT_NONE) { // Create a GOT entry for the tp-relative offset. Output_data_got<64, false>* got = target->got_section(symtab, layout); unsigned int r_sym = elfcpp::elf_r_sym<size>(reloc.get_r_info()); got->add_local_with_rel(object, r_sym, GOT_TYPE_TLS_OFFSET, target->rela_dyn_section(layout), elfcpp::R_X86_64_TPOFF64); } else if (optimized_type != tls::TLSOPT_TO_LE) unsupported_reloc_local(object, r_type); break; case elfcpp::R_X86_64_TPOFF32: // Local-exec layout->set_has_static_tls(); if (output_is_shared) unsupported_reloc_local(object, r_type); break; default: gold_unreachable(); } } break; case elfcpp::R_X86_64_SIZE32: case elfcpp::R_X86_64_SIZE64: default: gold_error(_("%s: unsupported reloc %u against local symbol"), object->name().c_str(), r_type); break; } } // Report an unsupported relocation against a global symbol. template<int size> void Target_x86_64<size>::Scan::unsupported_reloc_global( Sized_relobj_file<size, 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()); } // Returns true if this relocation type could be that of a function pointer. template<int size> inline bool Target_x86_64<size>::Scan::possible_function_pointer_reloc( Sized_relobj_file<size, false>* src_obj, unsigned int src_indx, unsigned int r_offset, unsigned int r_type) { switch (r_type) { case elfcpp::R_X86_64_64: case elfcpp::R_X86_64_32: case elfcpp::R_X86_64_32S: case elfcpp::R_X86_64_16: case elfcpp::R_X86_64_8: case elfcpp::R_X86_64_GOT64: case elfcpp::R_X86_64_GOT32: case elfcpp::R_X86_64_GOTPCREL64: case elfcpp::R_X86_64_GOTPCREL: case elfcpp::R_X86_64_GOTPCRELX: case elfcpp::R_X86_64_REX_GOTPCRELX: case elfcpp::R_X86_64_GOTPLT64: { return true; } case elfcpp::R_X86_64_PC32: { // This relocation may be used both for function calls and // for taking address of a function. We distinguish between // them by checking the opcodes. uint64_t sh_flags = src_obj->section_flags(src_indx); bool is_executable = (sh_flags & elfcpp::SHF_EXECINSTR) != 0; if (is_executable) { section_size_type stype; const unsigned char* view = src_obj->section_contents(src_indx, &stype, true); // call if (r_offset >= 1 && view[r_offset - 1] == 0xe8) return false; // jmp if (r_offset >= 1 && view[r_offset - 1] == 0xe9) return false; // jo/jno/jb/jnb/je/jne/jna/ja/js/jns/jp/jnp/jl/jge/jle/jg if (r_offset >= 2 && view[r_offset - 2] == 0x0f && view[r_offset - 1] >= 0x80 && view[r_offset - 1] <= 0x8f) return false; } // Be conservative and treat all others as function pointers. return true; } } return false; } // For safe ICF, scan a relocation for a local symbol to check if it // corresponds to a function pointer being taken. In that case mark // the function whose pointer was taken as not foldable. template<int size> inline bool Target_x86_64<size>::Scan::local_reloc_may_be_function_pointer( Symbol_table* , Layout* , Target_x86_64<size>* , Sized_relobj_file<size, false>* src_obj, unsigned int src_indx, Output_section* , const elfcpp::Rela<size, false>& reloc, unsigned int r_type, const elfcpp::Sym<size, false>&) { // When building a shared library, do not fold any local symbols as it is // not possible to distinguish pointer taken versus a call by looking at // the relocation types. if (parameters->options().shared()) return true; return possible_function_pointer_reloc(src_obj, src_indx, reloc.get_r_offset(), r_type); } // For safe ICF, scan a relocation for a global symbol to check if it // corresponds to a function pointer being taken. In that case mark // the function whose pointer was taken as not foldable. template<int size> inline bool Target_x86_64<size>::Scan::global_reloc_may_be_function_pointer( Symbol_table*, Layout* , Target_x86_64<size>* , Sized_relobj_file<size, false>* src_obj, unsigned int src_indx, Output_section* , const elfcpp::Rela<size, false>& reloc, unsigned int r_type, Symbol* gsym) { // When building a shared library, do not fold symbols whose visibility // is hidden, internal or protected. if (parameters->options().shared() && (gsym->visibility() == elfcpp::STV_INTERNAL || gsym->visibility() == elfcpp::STV_PROTECTED || gsym->visibility() == elfcpp::STV_HIDDEN)) return true; return possible_function_pointer_reloc(src_obj, src_indx, reloc.get_r_offset(), r_type); } // Scan a relocation for a global symbol. template<int size> inline void Target_x86_64<size>::Scan::global(Symbol_table* symtab, Layout* layout, Target_x86_64<size>* target, Sized_relobj_file<size, false>* object, unsigned int data_shndx, Output_section* output_section, const elfcpp::Rela<size, 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_X86_64_NONE: case elfcpp::R_X86_64_GNU_VTINHERIT: case elfcpp::R_X86_64_GNU_VTENTRY: break; case elfcpp::R_X86_64_64: case elfcpp::R_X86_64_32: case elfcpp::R_X86_64_32S: case elfcpp::R_X86_64_16: case elfcpp::R_X86_64_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 (!parameters->options().output_is_position_independent() && gsym->may_need_copy_reloc()) { target->copy_reloc(symtab, layout, object, data_shndx, output_section, gsym, reloc); } else if (((size == 64 && r_type == elfcpp::R_X86_64_64) || (size == 32 && r_type == elfcpp::R_X86_64_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* rela_dyn = target->rela_irelative_section(layout); unsigned int r_type = elfcpp::R_X86_64_IRELATIVE; rela_dyn->add_symbolless_global_addend(gsym, r_type, output_section, object, data_shndx, reloc.get_r_offset(), reloc.get_r_addend()); } else if (((size == 64 && r_type == elfcpp::R_X86_64_64) || (size == 32 && r_type == elfcpp::R_X86_64_32)) && gsym->can_use_relative_reloc(false)) { Reloc_section* rela_dyn = target->rela_dyn_section(layout); rela_dyn->add_global_relative(gsym, elfcpp::R_X86_64_RELATIVE, output_section, object, data_shndx, reloc.get_r_offset(), reloc.get_r_addend(), false); } else { this->check_non_pic(object, r_type, gsym); Reloc_section* rela_dyn = target->rela_dyn_section(layout); rela_dyn->add_global(gsym, r_type, output_section, object, data_shndx, reloc.get_r_offset(), reloc.get_r_addend()); } } } break; case elfcpp::R_X86_64_PC64: case elfcpp::R_X86_64_PC32: case elfcpp::R_X86_64_PC32_BND: case elfcpp::R_X86_64_PC16: case elfcpp::R_X86_64_PC8: { // Make a PLT entry if necessary. if (gsym->needs_plt_entry()) 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 (parameters->options().output_is_executable() && gsym->may_need_copy_reloc()) { target->copy_reloc(symtab, layout, object, data_shndx, output_section, gsym, reloc); } else { this->check_non_pic(object, r_type, gsym); Reloc_section* rela_dyn = target->rela_dyn_section(layout); rela_dyn->add_global(gsym, r_type, output_section, object, data_shndx, reloc.get_r_offset(), reloc.get_r_addend()); } } } break; case elfcpp::R_X86_64_GOT64: case elfcpp::R_X86_64_GOT32: case elfcpp::R_X86_64_GOTPCREL64: case elfcpp::R_X86_64_GOTPCREL: case elfcpp::R_X86_64_GOTPCRELX: case elfcpp::R_X86_64_REX_GOTPCRELX: case elfcpp::R_X86_64_GOTPLT64: { // The symbol requires a GOT entry. Output_data_got<64, false>* got = target->got_section(symtab, layout); // If we convert this from // mov foo@GOTPCREL(%rip), %reg // to lea foo(%rip), %reg. // OR // if we convert // (callq|jmpq) *foo@GOTPCRELX(%rip) to // (callq|jmpq) foo // in Relocate::relocate, then there is nothing to do here. // We cannot make these optimizations in incremental linking mode, // because we look at the opcode to decide whether or not to make // change, and during an incremental update, the change may have // already been applied. Lazy_view<size> view(object, data_shndx); size_t r_offset = reloc.get_r_offset(); if (!parameters->incremental() && r_offset >= 2 && Target_x86_64<size>::can_convert_mov_to_lea(gsym, r_type, r_offset, &view)) break; if (!parameters->incremental() && r_offset >= 2 && Target_x86_64<size>::can_convert_callq_to_direct(gsym, r_type, r_offset, &view)) break; 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 // dynamic relocation for it. Reloc_section* rela_dyn = target->rela_dyn_section(layout); // Use a GLOB_DAT rather than a RELATIVE reloc if: // // 1) The symbol may be defined in some other module. // // 2) We are building a shared library and this is a // protected symbol; using GLOB_DAT means that the dynamic // linker can use the address of the PLT in the main // executable when appropriate so that function address // comparisons work. // // 3) This is a STT_GNU_IFUNC symbol in position dependent // code, again so that function address comparisons work. if (gsym->is_from_dynobj() || gsym->is_undefined() || gsym->is_preemptible() || (gsym->visibility() == elfcpp::STV_PROTECTED && parameters->options().shared()) || (gsym->type() == elfcpp::STT_GNU_IFUNC && parameters->options().output_is_position_independent())) got->add_global_with_rel(gsym, GOT_TYPE_STANDARD, rela_dyn, elfcpp::R_X86_64_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); rela_dyn->add_global_relative(gsym, elfcpp::R_X86_64_RELATIVE, got, got_off, 0, false); } } } } break; case elfcpp::R_X86_64_PLT32: case elfcpp::R_X86_64_PLT32_BND: // 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_X86_64_GOTPC32: case elfcpp::R_X86_64_GOTOFF64: case elfcpp::R_X86_64_GOTPC64: case elfcpp::R_X86_64_PLTOFF64: // We need a GOT section. target->got_section(symtab, layout); // For PLTOFF64, we also need a PLT entry (but only if the // symbol is not fully resolved). if (r_type == elfcpp::R_X86_64_PLTOFF64 && !gsym->final_value_is_known()) target->make_plt_entry(symtab, layout, gsym); break; case elfcpp::R_X86_64_COPY: case elfcpp::R_X86_64_GLOB_DAT: case elfcpp::R_X86_64_JUMP_SLOT: case elfcpp::R_X86_64_RELATIVE: case elfcpp::R_X86_64_IRELATIVE: // These are outstanding tls relocs, which are unexpected when linking case elfcpp::R_X86_64_TPOFF64: case elfcpp::R_X86_64_DTPMOD64: case elfcpp::R_X86_64_TLSDESC: gold_error(_("%s: unexpected reloc %u in object file"), object->name().c_str(), r_type); break; // These are initial tls relocs, which are expected for global() case elfcpp::R_X86_64_TLSGD: // Global-dynamic case elfcpp::R_X86_64_GOTPC32_TLSDESC: // Global-dynamic (from ~oliva url) case elfcpp::R_X86_64_TLSDESC_CALL: case elfcpp::R_X86_64_TLSLD: // Local-dynamic case elfcpp::R_X86_64_DTPOFF32: case elfcpp::R_X86_64_DTPOFF64: case elfcpp::R_X86_64_GOTTPOFF: // Initial-exec case elfcpp::R_X86_64_TPOFF32: // Local-exec { // For the Initial-Exec model, we can treat undef symbols as final // when building an executable. const bool is_final = (gsym->final_value_is_known() || (r_type == elfcpp::R_X86_64_GOTTPOFF && gsym->is_undefined() && parameters->options().output_is_executable())); const tls::Tls_optimization optimized_type = Target_x86_64<size>::optimize_tls_reloc(is_final, r_type); switch (r_type) { case elfcpp::R_X86_64_TLSGD: // General-dynamic if (optimized_type == tls::TLSOPT_NONE) { // Create a pair of GOT entries for the module index and // dtv-relative offset. Output_data_got<64, false>* got = target->got_section(symtab, layout); got->add_global_pair_with_rel(gsym, GOT_TYPE_TLS_PAIR, target->rela_dyn_section(layout), elfcpp::R_X86_64_DTPMOD64, elfcpp::R_X86_64_DTPOFF64); } else if (optimized_type == tls::TLSOPT_TO_IE) { // Create a GOT entry for the tp-relative offset. Output_data_got<64, false>* got = target->got_section(symtab, layout); got->add_global_with_rel(gsym, GOT_TYPE_TLS_OFFSET, target->rela_dyn_section(layout), elfcpp::R_X86_64_TPOFF64); } else if (optimized_type != tls::TLSOPT_TO_LE) unsupported_reloc_global(object, r_type, gsym); break; case elfcpp::R_X86_64_GOTPC32_TLSDESC: target->define_tls_base_symbol(symtab, layout); if (optimized_type == tls::TLSOPT_NONE) { // Create reserved PLT and GOT entries for the resolver. target->reserve_tlsdesc_entries(symtab, layout); // Create a double GOT entry with an R_X86_64_TLSDESC // reloc. The R_X86_64_TLSDESC 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<64, false>* got = target->got_tlsdesc_section(); Reloc_section* rt = target->rela_tlsdesc_section(layout); got->add_global_pair_with_rel(gsym, GOT_TYPE_TLS_DESC, rt, elfcpp::R_X86_64_TLSDESC, 0); } else if (optimized_type == tls::TLSOPT_TO_IE) { // Create a GOT entry for the tp-relative offset. Output_data_got<64, false>* got = target->got_section(symtab, layout); got->add_global_with_rel(gsym, GOT_TYPE_TLS_OFFSET, target->rela_dyn_section(layout), elfcpp::R_X86_64_TPOFF64); } else if (optimized_type != tls::TLSOPT_TO_LE) unsupported_reloc_global(object, r_type, gsym); break; case elfcpp::R_X86_64_TLSDESC_CALL: break; case elfcpp::R_X86_64_TLSLD: // 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_X86_64_DTPOFF32: case elfcpp::R_X86_64_DTPOFF64: break; case elfcpp::R_X86_64_GOTTPOFF: // Initial-exec layout->set_has_static_tls(); if (optimized_type == tls::TLSOPT_NONE) { // Create a GOT entry for the tp-relative offset. Output_data_got<64, false>* got = target->got_section(symtab, layout); got->add_global_with_rel(gsym, GOT_TYPE_TLS_OFFSET, target->rela_dyn_section(layout), elfcpp::R_X86_64_TPOFF64); } else if (optimized_type != tls::TLSOPT_TO_LE) unsupported_reloc_global(object, r_type, gsym); break; case elfcpp::R_X86_64_TPOFF32: // Local-exec layout->set_has_static_tls(); if (parameters->options().shared()) unsupported_reloc_global(object, r_type, gsym); break; default: gold_unreachable(); } } break; case elfcpp::R_X86_64_SIZE32: case elfcpp::R_X86_64_SIZE64: default: gold_error(_("%s: unsupported reloc %u against global symbol %s"), object->name().c_str(), r_type, gsym->demangled_name().c_str()); break; } } template<int size> void Target_x86_64<size>::gc_process_relocs(Symbol_table* symtab, Layout* layout, Sized_relobj_file<size, 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) { typedef gold::Default_classify_reloc<elfcpp::SHT_RELA, size, false> Classify_reloc; if (sh_type == elfcpp::SHT_REL) { return; } gold::gc_process_relocs<size, false, Target_x86_64<size>, Scan, Classify_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. template<int size> void Target_x86_64<size>::scan_relocs(Symbol_table* symtab, Layout* layout, Sized_relobj_file<size, 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) { typedef gold::Default_classify_reloc<elfcpp::SHT_RELA, size, false> Classify_reloc; if (sh_type == elfcpp::SHT_REL) { gold_error(_("%s: unsupported REL reloc section"), object->name().c_str()); return; } gold::scan_relocs<size, false, Target_x86_64<size>, Scan, Classify_reloc>( symtab, layout, this, object, data_shndx, prelocs, reloc_count, output_section, needs_special_offset_handling, local_symbol_count, plocal_symbols); } // Finalize the sections. template<int size> void Target_x86_64<size>::do_finalize_sections( Layout* layout, const Input_objects*, Symbol_table* symtab) { const Reloc_section* rel_plt = (this->plt_ == NULL ? NULL : this->plt_->rela_plt()); layout->add_target_dynamic_tags(false, this->got_plt_, rel_plt, this->rela_dyn_, true, false); // Fill in some more dynamic tags. Output_data_dynamic* const odyn = layout->dynamic_data(); if (odyn != NULL) { if (this->plt_ != NULL && this->plt_->output_section() != NULL && this->plt_->has_tlsdesc_entry()) { unsigned int plt_offset = this->plt_->get_tlsdesc_plt_offset(); unsigned int got_offset = this->plt_->get_tlsdesc_got_offset(); this->got_->finalize_data_size(); odyn->add_section_plus_offset(elfcpp::DT_TLSDESC_PLT, this->plt_, plt_offset); odyn->add_section_plus_offset(elfcpp::DT_TLSDESC_GOT, this->got_, got_offset); } } // 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->rela_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) { uint64_t data_size = this->got_plt_->current_data_size(); symtab->get_sized_symbol<size>(sym)->set_symsize(data_size); } if (parameters->doing_static_link() && (this->plt_ == NULL || !this->plt_->has_irelative_section())) { // If linking statically, make sure that the __rela_iplt symbols // were defined if necessary, even if we didn't create a PLT. static const Define_symbol_in_segment syms[] = { { "__rela_iplt_start", // name elfcpp::PT_LOAD, // segment_type elfcpp::PF_W, // segment_flags_set elfcpp::PF(0), // segment_flags_clear 0, // value 0, // size elfcpp::STT_NOTYPE, // type elfcpp::STB_GLOBAL, // binding elfcpp::STV_HIDDEN, // visibility 0, // nonvis Symbol::SEGMENT_START, // offset_from_base true // only_if_ref }, { "__rela_iplt_end", // name elfcpp::PT_LOAD, // segment_type elfcpp::PF_W, // segment_flags_set elfcpp::PF(0), // segment_flags_clear 0, // value 0, // size elfcpp::STT_NOTYPE, // type elfcpp::STB_GLOBAL, // binding elfcpp::STV_HIDDEN, // visibility 0, // nonvis Symbol::SEGMENT_START, // offset_from_base true // only_if_ref } }; symtab->define_symbols(layout, 2, syms, layout->script_options()->saw_sections_clause()); } } // For x32, we need to handle PC-relative relocations using full 64-bit // arithmetic, so that we can detect relocation overflows properly. // This class overrides the pcrela32_check methods from the defaults in // Relocate_functions in reloc.h. template<int size> class X86_64_relocate_functions : public Relocate_functions<size, false> { public: typedef Relocate_functions<size, false> Base; // Do a simple PC relative relocation with the addend in the // relocation. static inline typename Base::Reloc_status pcrela32_check(unsigned char* view, typename elfcpp::Elf_types<64>::Elf_Addr value, typename elfcpp::Elf_types<64>::Elf_Swxword addend, typename elfcpp::Elf_types<64>::Elf_Addr address) { typedef typename elfcpp::Swap<32, false>::Valtype Valtype; Valtype* wv = reinterpret_cast<Valtype*>(view); value = value + addend - address; elfcpp::Swap<32, false>::writeval(wv, value); return (Bits<32>::has_overflow(value) ? Base::RELOC_OVERFLOW : Base::RELOC_OK); } // Do a simple PC relative relocation with a Symbol_value with the // addend in the relocation. static inline typename Base::Reloc_status pcrela32_check(unsigned char* view, const Sized_relobj_file<size, false>* object, const Symbol_value<size>* psymval, typename elfcpp::Elf_types<64>::Elf_Swxword addend, typename elfcpp::Elf_types<64>::Elf_Addr address) { typedef typename elfcpp::Swap<32, false>::Valtype Valtype; Valtype* wv = reinterpret_cast<Valtype*>(view); typename elfcpp::Elf_types<64>::Elf_Addr value; if (addend >= 0) value = psymval->value(object, addend); else { // For negative addends, get the symbol value without // the addend, then add the addend using 64-bit arithmetic. value = psymval->value(object, 0); value += addend; } value -= address; elfcpp::Swap<32, false>::writeval(wv, value); return (Bits<32>::has_overflow(value) ? Base::RELOC_OVERFLOW : Base::RELOC_OK); } }; // Perform a relocation. template<int size> inline bool Target_x86_64<size>::Relocate::relocate( const Relocate_info<size, false>* relinfo, unsigned int, Target_x86_64<size>* target, Output_section*, size_t relnum, const unsigned char* preloc, const Sized_symbol<size>* gsym, const Symbol_value<size>* psymval, unsigned char* view, typename elfcpp::Elf_types<size>::Elf_Addr address, section_size_type view_size) { typedef X86_64_relocate_functions<size> Reloc_funcs; const elfcpp::Rela<size, false> rela(preloc); unsigned int r_type = elfcpp::elf_r_type<size>(rela.get_r_info()); if (this->skip_call_tls_get_addr_) { if ((r_type != elfcpp::R_X86_64_PLT32 && r_type != elfcpp::R_X86_64_GOTPCREL && r_type != elfcpp::R_X86_64_GOTPCRELX && r_type != elfcpp::R_X86_64_PLT32_BND && r_type != elfcpp::R_X86_64_PC32_BND && r_type != elfcpp::R_X86_64_PC32) || gsym == NULL || strcmp(gsym->name(), "__tls_get_addr") != 0) { gold_error_at_location(relinfo, relnum, rela.get_r_offset(), _("missing expected TLS relocation")); this->skip_call_tls_get_addr_ = false; } else { this->skip_call_tls_get_addr_ = false; return false; } } if (view == NULL) return true; const Sized_relobj_file<size, false>* object = relinfo->object; // Pick the value to use for symbols defined in the PLT. Symbol_value<size> symval; if (gsym != NULL && gsym->use_plt_offset(Scan::get_reference_flags(r_type))) { symval.set_output_value(target->plt_address_for_global(gsym)); psymval = &symval; } else if (gsym == NULL && psymval->is_ifunc_symbol()) { unsigned int r_sym = elfcpp::elf_r_sym<size>(rela.get_r_info()); if (object->local_has_plt_offset(r_sym)) { symval.set_output_value(target->plt_address_for_local(object, r_sym)); psymval = &symval; } } const elfcpp::Elf_Xword addend = rela.get_r_addend(); // 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; // Since the actual offset is always negative, we use signed int to // support 64-bit GOT relocations. int got_offset = 0; switch (r_type) { case elfcpp::R_X86_64_GOT32: case elfcpp::R_X86_64_GOT64: case elfcpp::R_X86_64_GOTPLT64: case elfcpp::R_X86_64_GOTPCREL64: 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<size>(rela.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; } typename Reloc_funcs::Reloc_status rstatus = Reloc_funcs::RELOC_OK; switch (r_type) { case elfcpp::R_X86_64_NONE: case elfcpp::R_X86_64_GNU_VTINHERIT: case elfcpp::R_X86_64_GNU_VTENTRY: break; case elfcpp::R_X86_64_64: Reloc_funcs::rela64(view, object, psymval, addend); break; case elfcpp::R_X86_64_PC64: Reloc_funcs::pcrela64(view, object, psymval, addend, address); break; case elfcpp::R_X86_64_32: rstatus = Reloc_funcs::rela32_check(view, object, psymval, addend, Reloc_funcs::CHECK_UNSIGNED); break; case elfcpp::R_X86_64_32S: rstatus = Reloc_funcs::rela32_check(view, object, psymval, addend, Reloc_funcs::CHECK_SIGNED); break; case elfcpp::R_X86_64_PC32: case elfcpp::R_X86_64_PC32_BND: rstatus = Reloc_funcs::pcrela32_check(view, object, psymval, addend, address); break; case elfcpp::R_X86_64_16: Reloc_funcs::rela16(view, object, psymval, addend); break; case elfcpp::R_X86_64_PC16: Reloc_funcs::pcrela16(view, object, psymval, addend, address); break; case elfcpp::R_X86_64_8: Reloc_funcs::rela8(view, object, psymval, addend); break; case elfcpp::R_X86_64_PC8: Reloc_funcs::pcrela8(view, object, psymval, addend, address); break; case elfcpp::R_X86_64_PLT32: case elfcpp::R_X86_64_PLT32_BND: gold_assert(gsym == NULL || gsym->has_plt_offset() || gsym->final_value_is_known() || (gsym->is_defined() && !gsym->is_from_dynobj() && !gsym->is_preemptible())); // Note: while this code looks the same as for R_X86_64_PC32, it // behaves differently because psymval was set to point to // the PLT entry, rather than the symbol, in Scan::global(). rstatus = Reloc_funcs::pcrela32_check(view, object, psymval, addend, address); break; case elfcpp::R_X86_64_PLTOFF64: { gold_assert(gsym); gold_assert(gsym->has_plt_offset() || gsym->final_value_is_known()); typename elfcpp::Elf_types<size>::Elf_Addr got_address; // This is the address of GLOBAL_OFFSET_TABLE. got_address = target->got_plt_section()->address(); Reloc_funcs::rela64(view, object, psymval, addend - got_address); } break; case elfcpp::R_X86_64_GOT32: gold_assert(have_got_offset); Reloc_funcs::rela32(view, got_offset, addend); break; case elfcpp::R_X86_64_GOTPC32: { gold_assert(gsym); typename elfcpp::Elf_types<size>::Elf_Addr value; value = target->got_plt_section()->address(); Reloc_funcs::pcrela32_check(view, value, addend, address); } break; case elfcpp::R_X86_64_GOT64: case elfcpp::R_X86_64_GOTPLT64: // R_X86_64_GOTPLT64 is obsolete and treated the same as // GOT64. gold_assert(have_got_offset); Reloc_funcs::rela64(view, got_offset, addend); break; case elfcpp::R_X86_64_GOTPC64: { gold_assert(gsym); typename elfcpp::Elf_types<size>::Elf_Addr value; value = target->got_plt_section()->address(); Reloc_funcs::pcrela64(view, value, addend, address); } break; case elfcpp::R_X86_64_GOTOFF64: { typename elfcpp::Elf_types<size>::Elf_Addr value; value = (psymval->value(object, 0) - target->got_plt_section()->address()); Reloc_funcs::rela64(view, value, addend); } break; case elfcpp::R_X86_64_GOTPCREL: case elfcpp::R_X86_64_GOTPCRELX: case elfcpp::R_X86_64_REX_GOTPCRELX: { // Convert // mov foo@GOTPCREL(%rip), %reg // to lea foo(%rip), %reg. // if possible. if (!parameters->incremental() && ((gsym == NULL && rela.get_r_offset() >= 2 && view[-2] == 0x8b && !psymval->is_ifunc_symbol()) || (gsym != NULL && rela.get_r_offset() >= 2 && Target_x86_64<size>::can_convert_mov_to_lea(gsym, r_type, 0, &view)))) { view[-2] = 0x8d; Reloc_funcs::pcrela32(view, object, psymval, addend, address); } // Convert // callq *foo@GOTPCRELX(%rip) to // addr32 callq foo // and jmpq *foo@GOTPCRELX(%rip) to // jmpq foo // nop else if (!parameters->incremental() && gsym != NULL && rela.get_r_offset() >= 2 && Target_x86_64<size>::can_convert_callq_to_direct(gsym, r_type, 0, &view)) { if (view[-1] == 0x15) { // Convert callq *foo@GOTPCRELX(%rip) to addr32 callq. // Opcode of addr32 is 0x67 and opcode of direct callq is 0xe8. view[-2] = 0x67; view[-1] = 0xe8; // Convert GOTPCRELX to 32-bit pc relative reloc. Reloc_funcs::pcrela32(view, object, psymval, addend, address); } else { // Convert jmpq *foo@GOTPCRELX(%rip) to // jmpq foo // nop // The opcode of direct jmpq is 0xe9. view[-2] = 0xe9; // The opcode of nop is 0x90. view[3] = 0x90; // Convert GOTPCRELX to 32-bit pc relative reloc. jmpq is rip // relative and since the instruction following the jmpq is now // the nop, offset the address by 1 byte. The start of the // relocation also moves ahead by 1 byte. Reloc_funcs::pcrela32(&view[-1], object, psymval, addend, address - 1); } } else { 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<size>(rela.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()); } typename elfcpp::Elf_types<size>::Elf_Addr value; value = target->got_plt_section()->address() + got_offset; Reloc_funcs::pcrela32_check(view, value, addend, address); } } break; case elfcpp::R_X86_64_GOTPCREL64: { gold_assert(have_got_offset); typename elfcpp::Elf_types<size>::Elf_Addr value; value = target->got_plt_section()->address() + got_offset; Reloc_funcs::pcrela64(view, value, addend, address); } break; case elfcpp::R_X86_64_COPY: case elfcpp::R_X86_64_GLOB_DAT: case elfcpp::R_X86_64_JUMP_SLOT: case elfcpp::R_X86_64_RELATIVE: case elfcpp::R_X86_64_IRELATIVE: // These are outstanding tls relocs, which are unexpected when linking case elfcpp::R_X86_64_TPOFF64: case elfcpp::R_X86_64_DTPMOD64: case elfcpp::R_X86_64_TLSDESC: gold_error_at_location(relinfo, relnum, rela.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_X86_64_TLSGD: // Global-dynamic case elfcpp::R_X86_64_GOTPC32_TLSDESC: // Global-dynamic (from ~oliva url) case elfcpp::R_X86_64_TLSDESC_CALL: case elfcpp::R_X86_64_TLSLD: // Local-dynamic case elfcpp::R_X86_64_DTPOFF32: case elfcpp::R_X86_64_DTPOFF64: case elfcpp::R_X86_64_GOTTPOFF: // Initial-exec case elfcpp::R_X86_64_TPOFF32: // Local-exec this->relocate_tls(relinfo, target, relnum, rela, r_type, gsym, psymval, view, address, view_size); break; case elfcpp::R_X86_64_SIZE32: case elfcpp::R_X86_64_SIZE64: default: gold_error_at_location(relinfo, relnum, rela.get_r_offset(), _("unsupported reloc %u"), r_type); break; } if (rstatus == Reloc_funcs::RELOC_OVERFLOW) { if (gsym == NULL) { unsigned int r_sym = elfcpp::elf_r_sym<size>(rela.get_r_info()); gold_error_at_location(relinfo, relnum, rela.get_r_offset(), _("relocation overflow: " "reference to local symbol %u in %s"), r_sym, object->name().c_str()); } else if (gsym->is_defined() && gsym->source() == Symbol::FROM_OBJECT) { gold_error_at_location(relinfo, relnum, rela.get_r_offset(), _("relocation overflow: " "reference to '%s' defined in %s"), gsym->name(), gsym->object()->name().c_str()); } else { gold_error_at_location(relinfo, relnum, rela.get_r_offset(), _("relocation overflow: reference to '%s'"), gsym->name()); } } return true; } // Perform a TLS relocation. template<int size> inline void Target_x86_64<size>::Relocate::relocate_tls( const Relocate_info<size, false>* relinfo, Target_x86_64<size>* target, size_t relnum, const elfcpp::Rela<size, false>& rela, unsigned int r_type, const Sized_symbol<size>* gsym, const Symbol_value<size>* psymval, unsigned char* view, typename elfcpp::Elf_types<size>::Elf_Addr address, section_size_type view_size) { Output_segment* tls_segment = relinfo->layout->tls_segment(); const Sized_relobj_file<size, false>* object = relinfo->object; const elfcpp::Elf_Xword addend = rela.get_r_addend(); elfcpp::Shdr<size, false> data_shdr(relinfo->data_shdr); bool is_executable = (data_shdr.get_sh_flags() & elfcpp::SHF_EXECINSTR) != 0; typename elfcpp::Elf_types<size>::Elf_Addr value = psymval->value(relinfo->object, 0); const bool is_final = (gsym == NULL ? !parameters->options().shared() : gsym->final_value_is_known()); tls::Tls_optimization optimized_type = Target_x86_64<size>::optimize_tls_reloc(is_final, r_type); switch (r_type) { case elfcpp::R_X86_64_TLSGD: // Global-dynamic if (!is_executable && optimized_type == tls::TLSOPT_TO_LE) { // If this code sequence is used in a non-executable section, // we will not optimize the R_X86_64_DTPOFF32/64 relocation, // on the assumption that it's being used by itself in a debug // section. Therefore, in the unlikely event that the code // sequence appears in a non-executable section, we simply // leave it unoptimized. optimized_type = tls::TLSOPT_NONE; } if (optimized_type == tls::TLSOPT_TO_LE) { if (tls_segment == NULL) { gold_assert(parameters->errors()->error_count() > 0 || issue_undefined_symbol_error(gsym)); return; } this->tls_gd_to_le(relinfo, relnum, tls_segment, rela, r_type, value, view, view_size); break; } else { unsigned int got_type = (optimized_type == tls::TLSOPT_TO_IE ? GOT_TYPE_TLS_OFFSET : 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<size>(rela.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) { value = target->got_plt_section()->address() + got_offset; this->tls_gd_to_ie(relinfo, relnum, rela, r_type, value, view, address, view_size); break; } else if (optimized_type == tls::TLSOPT_NONE) { // Relocate the field with the offset of the pair of GOT // entries. value = target->got_plt_section()->address() + got_offset; Relocate_functions<size, false>::pcrela32(view, value, addend, address); break; } } gold_error_at_location(relinfo, relnum, rela.get_r_offset(), _("unsupported reloc %u"), r_type); break; case elfcpp::R_X86_64_GOTPC32_TLSDESC: // Global-dynamic (from ~oliva url) case elfcpp::R_X86_64_TLSDESC_CALL: if (!is_executable && optimized_type == tls::TLSOPT_TO_LE) { // See above comment for R_X86_64_TLSGD. optimized_type = tls::TLSOPT_NONE; } if (optimized_type == tls::TLSOPT_TO_LE) { if (tls_segment == NULL) { gold_assert(parameters->errors()->error_count() > 0 || issue_undefined_symbol_error(gsym)); return; } this->tls_desc_gd_to_le(relinfo, relnum, tls_segment, rela, r_type, value, view, view_size); break; } else { unsigned int got_type = (optimized_type == tls::TLSOPT_TO_IE ? GOT_TYPE_TLS_OFFSET : GOT_TYPE_TLS_DESC); unsigned int got_offset = 0; if (r_type == elfcpp::R_X86_64_GOTPC32_TLSDESC && 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<size>(rela.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) { value = target->got_plt_section()->address() + got_offset; this->tls_desc_gd_to_ie(relinfo, relnum, rela, r_type, value, view, address, view_size); break; } else if (optimized_type == tls::TLSOPT_NONE) { if (r_type == elfcpp::R_X86_64_GOTPC32_TLSDESC) { // Relocate the field with the offset of the pair of GOT // entries. value = target->got_plt_section()->address() + got_offset; Relocate_functions<size, false>::pcrela32(view, value, addend, address); } break; } } gold_error_at_location(relinfo, relnum, rela.get_r_offset(), _("unsupported reloc %u"), r_type); break; case elfcpp::R_X86_64_TLSLD: // Local-dynamic if (!is_executable && optimized_type == tls::TLSOPT_TO_LE) { // See above comment for R_X86_64_TLSGD. optimized_type = tls::TLSOPT_NONE; } if (optimized_type == tls::TLSOPT_TO_LE) { if (tls_segment == NULL) { gold_assert(parameters->errors()->error_count() > 0 || issue_undefined_symbol_error(gsym)); return; } this->tls_ld_to_le(relinfo, relnum, tls_segment, rela, 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()); value = target->got_plt_section()->address() + got_offset; Relocate_functions<size, false>::pcrela32(view, value, addend, address); break; } gold_error_at_location(relinfo, relnum, rela.get_r_offset(), _("unsupported reloc %u"), r_type); break; case elfcpp::R_X86_64_DTPOFF32: // This relocation type is used in debugging information. // In that case we need to not optimize the value. If the // section is not executable, then we assume we should not // optimize this reloc. See comments above for R_X86_64_TLSGD, // R_X86_64_GOTPC32_TLSDESC, R_X86_64_TLSDESC_CALL, and // R_X86_64_TLSLD. if (optimized_type == tls::TLSOPT_TO_LE && is_executable) { if (tls_segment == NULL) { gold_assert(parameters->errors()->error_count() > 0 || issue_undefined_symbol_error(gsym)); return; } value -= tls_segment->memsz(); } Relocate_functions<size, false>::rela32(view, value, addend); break; case elfcpp::R_X86_64_DTPOFF64: // See R_X86_64_DTPOFF32, just above, for why we check for is_executable. if (optimized_type == tls::TLSOPT_TO_LE && is_executable) { if (tls_segment == NULL) { gold_assert(parameters->errors()->error_count() > 0 || issue_undefined_symbol_error(gsym)); return; } value -= tls_segment->memsz(); } Relocate_functions<size, false>::rela64(view, value, addend); break; case elfcpp::R_X86_64_GOTTPOFF: // Initial-exec if (gsym != NULL && gsym->is_undefined() && parameters->options().output_is_executable()) { Target_x86_64<size>::Relocate::tls_ie_to_le(relinfo, relnum, NULL, rela, r_type, value, view, view_size); break; } else if (optimized_type == tls::TLSOPT_TO_LE) { if (tls_segment == NULL) { gold_assert(parameters->errors()->error_count() > 0 || issue_undefined_symbol_error(gsym)); return; } Target_x86_64<size>::Relocate::tls_ie_to_le(relinfo, relnum, tls_segment, rela, r_type, value, view, view_size); break; } else if (optimized_type == tls::TLSOPT_NONE) { // Relocate the field with the offset of the GOT entry for // the tp-relative offset of the symbol. unsigned int got_offset; if (gsym != NULL) { gold_assert(gsym->has_got_offset(GOT_TYPE_TLS_OFFSET)); got_offset = (gsym->got_offset(GOT_TYPE_TLS_OFFSET) - target->got_size()); } else { unsigned int r_sym = elfcpp::elf_r_sym<size>(rela.get_r_info()); gold_assert(object->local_has_got_offset(r_sym, GOT_TYPE_TLS_OFFSET)); got_offset = (object->local_got_offset(r_sym, GOT_TYPE_TLS_OFFSET) - target->got_size()); } value = target->got_plt_section()->address() + got_offset; Relocate_functions<size, false>::pcrela32(view, value, addend, address); break; } gold_error_at_location(relinfo, relnum, rela.get_r_offset(), _("unsupported reloc type %u"), r_type); break; case elfcpp::R_X86_64_TPOFF32: // Local-exec if (tls_segment == NULL) { gold_assert(parameters->errors()->error_count() > 0 || issue_undefined_symbol_error(gsym)); return; } value -= tls_segment->memsz(); Relocate_functions<size, false>::rela32(view, value, addend); break; } } // Do a relocation in which we convert a TLS General-Dynamic to an // Initial-Exec. template<int size> inline void Target_x86_64<size>::Relocate::tls_gd_to_ie( const Relocate_info<size, false>* relinfo, size_t relnum, const elfcpp::Rela<size, false>& rela, unsigned int, typename elfcpp::Elf_types<size>::Elf_Addr value, unsigned char* view, typename elfcpp::Elf_types<size>::Elf_Addr address, section_size_type view_size) { // For SIZE == 64: // .byte 0x66; leaq foo@tlsgd(%rip),%rdi; // .word 0x6666; rex64; call __tls_get_addr@PLT // ==> movq %fs:0,%rax; addq x@gottpoff(%rip),%rax // .byte 0x66; leaq foo@tlsgd(%rip),%rdi; // .word 0x66; rex64; call *__tls_get_addr@GOTPCREL(%rip) // ==> movq %fs:0,%rax; addq x@gottpoff(%rip),%rax // For SIZE == 32: // leaq foo@tlsgd(%rip),%rdi; // .word 0x6666; rex64; call __tls_get_addr@PLT // ==> movl %fs:0,%eax; addq x@gottpoff(%rip),%rax // leaq foo@tlsgd(%rip),%rdi; // .word 0x66; rex64; call *__tls_get_addr@GOTPCREL(%rip) // ==> movl %fs:0,%eax; addq x@gottpoff(%rip),%rax tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 12); tls::check_tls(relinfo, relnum, rela.get_r_offset(), (memcmp(view + 4, "\x66\x66\x48\xe8", 4) == 0 || memcmp(view + 4, "\x66\x48\xff", 3) == 0)); if (size == 64) { tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -4); tls::check_tls(relinfo, relnum, rela.get_r_offset(), (memcmp(view - 4, "\x66\x48\x8d\x3d", 4) == 0)); memcpy(view - 4, "\x64\x48\x8b\x04\x25\0\0\0\0\x48\x03\x05\0\0\0\0", 16); } else { tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -3); tls::check_tls(relinfo, relnum, rela.get_r_offset(), (memcmp(view - 3, "\x48\x8d\x3d", 3) == 0)); memcpy(view - 3, "\x64\x8b\x04\x25\0\0\0\0\x48\x03\x05\0\0\0\0", 15); } const elfcpp::Elf_Xword addend = rela.get_r_addend(); Relocate_functions<size, false>::pcrela32(view + 8, value, addend - 8, address); // 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 a // Local-Exec. template<int size> inline void Target_x86_64<size>::Relocate::tls_gd_to_le( const Relocate_info<size, false>* relinfo, size_t relnum, Output_segment* tls_segment, const elfcpp::Rela<size, false>& rela, unsigned int, typename elfcpp::Elf_types<size>::Elf_Addr value, unsigned char* view, section_size_type view_size) { // For SIZE == 64: // .byte 0x66; leaq foo@tlsgd(%rip),%rdi; // .word 0x6666; rex64; call __tls_get_addr@PLT // ==> movq %fs:0,%rax; leaq x@tpoff(%rax),%rax // .byte 0x66; leaq foo@tlsgd(%rip),%rdi; // .word 0x66; rex64; call *__tls_get_addr@GOTPCREL(%rip) // ==> movq %fs:0,%rax; leaq x@tpoff(%rax),%rax // For SIZE == 32: // leaq foo@tlsgd(%rip),%rdi; // .word 0x6666; rex64; call __tls_get_addr@PLT // ==> movl %fs:0,%eax; leaq x@tpoff(%rax),%rax // leaq foo@tlsgd(%rip),%rdi; // .word 0x66; rex64; call *__tls_get_addr@GOTPCREL(%rip) // ==> movl %fs:0,%eax; leaq x@tpoff(%rax),%rax tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 12); tls::check_tls(relinfo, relnum, rela.get_r_offset(), (memcmp(view + 4, "\x66\x66\x48\xe8", 4) == 0 || memcmp(view + 4, "\x66\x48\xff", 3) == 0)); if (size == 64) { tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -4); tls::check_tls(relinfo, relnum, rela.get_r_offset(), (memcmp(view - 4, "\x66\x48\x8d\x3d", 4) == 0)); memcpy(view - 4, "\x64\x48\x8b\x04\x25\0\0\0\0\x48\x8d\x80\0\0\0\0", 16); } else { tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -3); tls::check_tls(relinfo, relnum, rela.get_r_offset(), (memcmp(view - 3, "\x48\x8d\x3d", 3) == 0)); memcpy(view - 3, "\x64\x8b\x04\x25\0\0\0\0\x48\x8d\x80\0\0\0\0", 15); } value -= tls_segment->memsz(); Relocate_functions<size, false>::rela32(view + 8, value, 0); // 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 TLSDESC-style General-Dynamic to Initial-Exec transition. template<int size> inline void Target_x86_64<size>::Relocate::tls_desc_gd_to_ie( const Relocate_info<size, false>* relinfo, size_t relnum, const elfcpp::Rela<size, false>& rela, unsigned int r_type, typename elfcpp::Elf_types<size>::Elf_Addr value, unsigned char* view, typename elfcpp::Elf_types<size>::Elf_Addr address, section_size_type view_size) { if (r_type == elfcpp::R_X86_64_GOTPC32_TLSDESC) { // leaq foo@tlsdesc(%rip), %rax // ==> movq foo@gottpoff(%rip), %rax tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -3); tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 4); tls::check_tls(relinfo, relnum, rela.get_r_offset(), view[-3] == 0x48 && view[-2] == 0x8d && view[-1] == 0x05); view[-2] = 0x8b; const elfcpp::Elf_Xword addend = rela.get_r_addend(); Relocate_functions<size, false>::pcrela32(view, value, addend, address); } else { // call *foo@tlscall(%rax) // ==> nop; nop gold_assert(r_type == elfcpp::R_X86_64_TLSDESC_CALL); tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 2); tls::check_tls(relinfo, relnum, rela.get_r_offset(), view[0] == 0xff && view[1] == 0x10); view[0] = 0x66; view[1] = 0x90; } } // Do a TLSDESC-style General-Dynamic to Local-Exec transition. template<int size> inline void Target_x86_64<size>::Relocate::tls_desc_gd_to_le( const Relocate_info<size, false>* relinfo, size_t relnum, Output_segment* tls_segment, const elfcpp::Rela<size, false>& rela, unsigned int r_type, typename elfcpp::Elf_types<size>::Elf_Addr value, unsigned char* view, section_size_type view_size) { if (r_type == elfcpp::R_X86_64_GOTPC32_TLSDESC) { // leaq foo@tlsdesc(%rip), %rax // ==> movq foo@tpoff, %rax tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -3); tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 4); tls::check_tls(relinfo, relnum, rela.get_r_offset(), view[-3] == 0x48 && view[-2] == 0x8d && view[-1] == 0x05); view[-2] = 0xc7; view[-1] = 0xc0; value -= tls_segment->memsz(); Relocate_functions<size, false>::rela32(view, value, 0); } else { // call *foo@tlscall(%rax) // ==> nop; nop gold_assert(r_type == elfcpp::R_X86_64_TLSDESC_CALL); tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 2); tls::check_tls(relinfo, relnum, rela.get_r_offset(), view[0] == 0xff && view[1] == 0x10); view[0] = 0x66; view[1] = 0x90; } } template<int size> inline void Target_x86_64<size>::Relocate::tls_ld_to_le( const Relocate_info<size, false>* relinfo, size_t relnum, Output_segment*, const elfcpp::Rela<size, false>& rela, unsigned int, typename elfcpp::Elf_types<size>::Elf_Addr, unsigned char* view, section_size_type view_size) { // leaq foo@tlsld(%rip),%rdi; call __tls_get_addr@plt; // For SIZE == 64: // ... leq foo@dtpoff(%rax),%reg // ==> .word 0x6666; .byte 0x66; movq %fs:0,%rax ... leaq x@tpoff(%rax),%rdx // For SIZE == 32: // ... leq foo@dtpoff(%rax),%reg // ==> nopl 0x0(%rax); movl %fs:0,%eax ... leaq x@tpoff(%rax),%rdx // leaq foo@tlsld(%rip),%rdi; call *__tls_get_addr@GOTPCREL(%rip) // For SIZE == 64: // ... leq foo@dtpoff(%rax),%reg // ==> .word 0x6666; .byte 0x6666; movq %fs:0,%rax ... leaq x@tpoff(%rax),%rdx // For SIZE == 32: // ... leq foo@dtpoff(%rax),%reg // ==> nopw 0x0(%rax); movl %fs:0,%eax ... leaq x@tpoff(%rax),%rdx tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -3); tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 9); tls::check_tls(relinfo, relnum, rela.get_r_offset(), view[-3] == 0x48 && view[-2] == 0x8d && view[-1] == 0x3d); tls::check_tls(relinfo, relnum, rela.get_r_offset(), view[4] == 0xe8 || view[4] == 0xff); if (view[4] == 0xe8) { if (size == 64) memcpy(view - 3, "\x66\x66\x66\x64\x48\x8b\x04\x25\0\0\0\0", 12); else memcpy(view - 3, "\x0f\x1f\x40\x00\x64\x8b\x04\x25\0\0\0\0", 12); } else { if (size == 64) memcpy(view - 3, "\x66\x66\x66\x66\x64\x48\x8b\x04\x25\0\0\0\0", 13); else memcpy(view - 3, "\x66\x0f\x1f\x40\x00\x64\x8b\x04\x25\0\0\0\0", 13); } // 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. template<int size> inline void Target_x86_64<size>::Relocate::tls_ie_to_le( const Relocate_info<size, false>* relinfo, size_t relnum, Output_segment* tls_segment, const elfcpp::Rela<size, false>& rela, unsigned int, typename elfcpp::Elf_types<size>::Elf_Addr value, unsigned char* view, section_size_type view_size) { // We need to examine the opcodes to figure out which instruction we // are looking at. // movq foo@gottpoff(%rip),%reg ==> movq $YY,%reg // addq foo@gottpoff(%rip),%reg ==> addq $YY,%reg tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -3); tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 4); unsigned char op1 = view[-3]; unsigned char op2 = view[-2]; unsigned char op3 = view[-1]; unsigned char reg = op3 >> 3; if (op2 == 0x8b) { // movq if (op1 == 0x4c) view[-3] = 0x49; else if (size == 32 && op1 == 0x44) view[-3] = 0x41; view[-2] = 0xc7; view[-1] = 0xc0 | reg; } else if (reg == 4) { // Special handling for %rsp. if (op1 == 0x4c) view[-3] = 0x49; else if (size == 32 && op1 == 0x44) view[-3] = 0x41; view[-2] = 0x81; view[-1] = 0xc0 | reg; } else { // addq if (op1 == 0x4c) view[-3] = 0x4d; else if (size == 32 && op1 == 0x44) view[-3] = 0x45; view[-2] = 0x8d; view[-1] = 0x80 | reg | (reg << 3); } if (tls_segment != NULL) value -= tls_segment->memsz(); Relocate_functions<size, false>::rela32(view, value, 0); } // Relocate section data. template<int size> void Target_x86_64<size>::relocate_section( const Relocate_info<size, 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, typename elfcpp::Elf_types<size>::Elf_Addr address, section_size_type view_size, const Reloc_symbol_changes* reloc_symbol_changes) { typedef gold::Default_classify_reloc<elfcpp::SHT_RELA, size, false> Classify_reloc; gold_assert(sh_type == elfcpp::SHT_RELA); gold::relocate_section<size, false, Target_x86_64<size>, Relocate, gold::Default_comdat_behavior, Classify_reloc>( relinfo, this, prelocs, reloc_count, output_section, needs_special_offset_handling, view, address, view_size, reloc_symbol_changes); } // Apply an incremental relocation. Incremental relocations always refer // to global symbols. template<int size> void Target_x86_64<size>::apply_relocation( const Relocate_info<size, false>* relinfo, typename elfcpp::Elf_types<size>::Elf_Addr r_offset, unsigned int r_type, typename elfcpp::Elf_types<size>::Elf_Swxword r_addend, const Symbol* gsym, unsigned char* view, typename elfcpp::Elf_types<size>::Elf_Addr address, section_size_type view_size) { gold::apply_relocation<size, false, Target_x86_64<size>, typename Target_x86_64<size>::Relocate>( relinfo, this, r_offset, r_type, r_addend, gsym, view, address, view_size); } // Scan the relocs during a relocatable link. template<int size> void Target_x86_64<size>::scan_relocatable_relocs( Symbol_table* symtab, Layout* layout, Sized_relobj_file<size, 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) { typedef gold::Default_classify_reloc<elfcpp::SHT_RELA, size, false> Classify_reloc; typedef gold::Default_scan_relocatable_relocs<Classify_reloc> Scan_relocatable_relocs; gold_assert(sh_type == elfcpp::SHT_RELA); gold::scan_relocatable_relocs<size, false, Scan_relocatable_relocs>( symtab, layout, object, data_shndx, prelocs, reloc_count, output_section, needs_special_offset_handling, local_symbol_count, plocal_symbols, rr); } // Scan the relocs for --emit-relocs. template<int size> void Target_x86_64<size>::emit_relocs_scan( Symbol_table* symtab, Layout* layout, Sized_relobj_file<size, 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_syms, Relocatable_relocs* rr) { typedef gold::Default_classify_reloc<elfcpp::SHT_RELA, size, false> Classify_reloc; typedef gold::Default_emit_relocs_strategy<Classify_reloc> Emit_relocs_strategy; gold_assert(sh_type == elfcpp::SHT_RELA); gold::scan_relocatable_relocs<size, false, Emit_relocs_strategy>( symtab, layout, object, data_shndx, prelocs, reloc_count, output_section, needs_special_offset_handling, local_symbol_count, plocal_syms, rr); } // Relocate a section during a relocatable link. template<int size> void Target_x86_64<size>::relocate_relocs( const Relocate_info<size, false>* relinfo, unsigned int sh_type, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, typename elfcpp::Elf_types<size>::Elf_Off offset_in_output_section, unsigned char* view, typename elfcpp::Elf_types<size>::Elf_Addr view_address, section_size_type view_size, unsigned char* reloc_view, section_size_type reloc_view_size) { typedef gold::Default_classify_reloc<elfcpp::SHT_RELA, size, false> Classify_reloc; gold_assert(sh_type == elfcpp::SHT_RELA); gold::relocate_relocs<size, false, Classify_reloc>( relinfo, prelocs, reloc_count, output_section, offset_in_output_section, 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. template<int size> uint64_t Target_x86_64<size>::do_dynsym_value(const Symbol* gsym) const { gold_assert(gsym->is_from_dynobj() && gsym->has_plt_offset()); return this->plt_address_for_global(gsym); } // Return a string used to fill a code section with nops to take up // the specified length. template<int size> std::string Target_x86_64<size>::do_code_fill(section_size_type length) const { if (length >= 16) { // Build a jmpq 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, static_cast<char>(0x90))); } // Nop sequences of various lengths. const char nop1[1] = { '\x90' }; // nop const char nop2[2] = { '\x66', '\x90' }; // xchg %ax %ax const char nop3[3] = { '\x0f', '\x1f', '\x00' }; // nop (%rax) const char nop4[4] = { '\x0f', '\x1f', '\x40', // nop 0(%rax) '\x00'}; const char nop5[5] = { '\x0f', '\x1f', '\x44', // nop 0(%rax,%rax,1) '\x00', '\x00' }; const char nop6[6] = { '\x66', '\x0f', '\x1f', // nopw 0(%rax,%rax,1) '\x44', '\x00', '\x00' }; const char nop7[7] = { '\x0f', '\x1f', '\x80', // nopl 0L(%rax) '\x00', '\x00', '\x00', '\x00' }; const char nop8[8] = { '\x0f', '\x1f', '\x84', // nopl 0L(%rax,%rax,1) '\x00', '\x00', '\x00', '\x00', '\x00' }; const char nop9[9] = { '\x66', '\x0f', '\x1f', // nopw 0L(%rax,%rax,1) '\x84', '\x00', '\x00', '\x00', '\x00', '\x00' }; const char nop10[10] = { '\x66', '\x2e', '\x0f', // nopw %cs:0L(%rax,%rax,1) '\x1f', '\x84', '\x00', '\x00', '\x00', '\x00', '\x00' }; const char nop11[11] = { '\x66', '\x66', '\x2e', // data16 '\x0f', '\x1f', '\x84', // nopw %cs:0L(%rax,%rax,1) '\x00', '\x00', '\x00', '\x00', '\x00' }; const char nop12[12] = { '\x66', '\x66', '\x66', // data16; data16 '\x2e', '\x0f', '\x1f', // nopw %cs:0L(%rax,%rax,1) '\x84', '\x00', '\x00', '\x00', '\x00', '\x00' }; const char nop13[13] = { '\x66', '\x66', '\x66', // data16; data16; data16 '\x66', '\x2e', '\x0f', // nopw %cs:0L(%rax,%rax,1) '\x1f', '\x84', '\x00', '\x00', '\x00', '\x00', '\x00' }; const char nop14[14] = { '\x66', '\x66', '\x66', // data16; data16; data16 '\x66', '\x66', '\x2e', // data16 '\x0f', '\x1f', '\x84', // nopw %cs:0L(%rax,%rax,1) '\x00', '\x00', '\x00', '\x00', '\x00' }; const char nop15[15] = { '\x66', '\x66', '\x66', // data16; data16; data16 '\x66', '\x66', '\x66', // data16; data16 '\x2e', '\x0f', '\x1f', // nopw %cs:0L(%rax,%rax,1) '\x84', '\x00', '\x00', '\x00', '\x00', '\x00' }; 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 the addend to use for a target specific relocation. The // only target specific relocation is R_X86_64_TLSDESC for a local // symbol. We want to set the addend is the offset of the local // symbol in the TLS segment. template<int size> uint64_t Target_x86_64<size>::do_reloc_addend(void* arg, unsigned int r_type, uint64_t) const { gold_assert(r_type == elfcpp::R_X86_64_TLSDESC); uintptr_t intarg = reinterpret_cast<uintptr_t>(arg); gold_assert(intarg < this->tlsdesc_reloc_info_.size()); const Tlsdesc_info& ti(this->tlsdesc_reloc_info_[intarg]); const Symbol_value<size>* psymval = ti.object->local_symbol(ti.r_sym); gold_assert(psymval->is_tls_symbol()); // The value of a TLS symbol is the offset in the TLS segment. return psymval->value(ti.object, 0); } // Return the value to use for the base of a DW_EH_PE_datarel offset // in an FDE. Solaris and SVR4 use DW_EH_PE_datarel because their // assembler can not write out the difference between two labels in // different sections, so instead of using a pc-relative value they // use an offset from the GOT. template<int size> uint64_t Target_x86_64<size>::do_ehframe_datarel_base() const { gold_assert(this->global_offset_table_ != NULL); Symbol* sym = this->global_offset_table_; Sized_symbol<size>* ssym = static_cast<Sized_symbol<size>*>(sym); return ssym->value(); } // 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. static const unsigned char cmp_insn_32[] = { 0x64, 0x3b, 0x24, 0x25 }; static const unsigned char lea_r10_insn_32[] = { 0x44, 0x8d, 0x94, 0x24 }; static const unsigned char lea_r11_insn_32[] = { 0x44, 0x8d, 0x9c, 0x24 }; static const unsigned char cmp_insn_64[] = { 0x64, 0x48, 0x3b, 0x24, 0x25 }; static const unsigned char lea_r10_insn_64[] = { 0x4c, 0x8d, 0x94, 0x24 }; static const unsigned char lea_r11_insn_64[] = { 0x4c, 0x8d, 0x9c, 0x24 }; template<int size> void Target_x86_64<size>::do_calls_non_split(Relobj* object, unsigned int shndx, section_offset_type fnoffset, section_size_type fnsize, const unsigned char*, size_t, unsigned char* view, section_size_type view_size, std::string* from, std::string* to) const { const char* const cmp_insn = reinterpret_cast<const char*> (size == 32 ? cmp_insn_32 : cmp_insn_64); const char* const lea_r10_insn = reinterpret_cast<const char*> (size == 32 ? lea_r10_insn_32 : lea_r10_insn_64); const char* const lea_r11_insn = reinterpret_cast<const char*> (size == 32 ? lea_r11_insn_32 : lea_r11_insn_64); const size_t cmp_insn_len = (size == 32 ? sizeof(cmp_insn_32) : sizeof(cmp_insn_64)); const size_t lea_r10_insn_len = (size == 32 ? sizeof(lea_r10_insn_32) : sizeof(lea_r10_insn_64)); const size_t lea_r11_insn_len = (size == 32 ? sizeof(lea_r11_insn_32) : sizeof(lea_r11_insn_64)); const size_t nop_len = (size == 32 ? 7 : 8); // The function starts with a comparison of the stack pointer and a // field in the TCB. This is followed by a jump. // cmp %fs:NN,%rsp if (this->match_view(view, view_size, fnoffset, cmp_insn, cmp_insn_len) && fnsize > nop_len + 1) { // 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, nop_len); } // lea NN(%rsp),%r10 // lea NN(%rsp),%r11 else if ((this->match_view(view, view_size, fnoffset, lea_r10_insn, lea_r10_insn_len) || this->match_view(view, view_size, fnoffset, lea_r11_insn, lea_r11_insn_len)) && fnsize > 8) { // 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 + 4; 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 x86_64 object files. Note this is never instantiated // directly. It's only used in Target_selector_x86_64_nacl, below. template<int size> class Target_selector_x86_64 : public Target_selector_freebsd { public: Target_selector_x86_64() : Target_selector_freebsd(elfcpp::EM_X86_64, size, false, (size == 64 ? "elf64-x86-64" : "elf32-x86-64"), (size == 64 ? "elf64-x86-64-freebsd" : "elf32-x86-64-freebsd"), (size == 64 ? "elf_x86_64" : "elf32_x86_64")) { } Target* do_instantiate_target() { return new Target_x86_64<size>(); } }; // NaCl variant. It uses different PLT contents. template<int size> class Output_data_plt_x86_64_nacl : public Output_data_plt_x86_64<size> { public: Output_data_plt_x86_64_nacl(Layout* layout, Output_data_got<64, false>* got, Output_data_got_plt_x86_64* got_plt, Output_data_space* got_irelative) : Output_data_plt_x86_64<size>(layout, plt_entry_size, got, got_plt, got_irelative) { } Output_data_plt_x86_64_nacl(Layout* layout, Output_data_got<64, false>* got, Output_data_got_plt_x86_64* got_plt, Output_data_space* got_irelative, unsigned int plt_count) : Output_data_plt_x86_64<size>(layout, plt_entry_size, got, got_plt, got_irelative, plt_count) { } protected: virtual unsigned int do_get_plt_entry_size() const { return plt_entry_size; } virtual void do_add_eh_frame(Layout* layout) { layout->add_eh_frame_for_plt(this, this->plt_eh_frame_cie, this->plt_eh_frame_cie_size, plt_eh_frame_fde, plt_eh_frame_fde_size); } virtual void do_fill_first_plt_entry(unsigned char* pov, typename elfcpp::Elf_types<size>::Elf_Addr got_addr, typename elfcpp::Elf_types<size>::Elf_Addr plt_addr); virtual unsigned int do_fill_plt_entry(unsigned char* pov, typename elfcpp::Elf_types<size>::Elf_Addr got_address, typename elfcpp::Elf_types<size>::Elf_Addr plt_address, unsigned int got_offset, unsigned int plt_offset, unsigned int plt_index); virtual void do_fill_tlsdesc_entry(unsigned char* pov, typename elfcpp::Elf_types<size>::Elf_Addr got_address, typename elfcpp::Elf_types<size>::Elf_Addr plt_address, typename elfcpp::Elf_types<size>::Elf_Addr got_base, unsigned int tlsdesc_got_offset, unsigned int plt_offset); private: // The size of an entry in the PLT. static const int plt_entry_size = 64; // The first entry in the PLT. static const unsigned char first_plt_entry[plt_entry_size]; // Other entries in the PLT for an executable. static const unsigned char plt_entry[plt_entry_size]; // The reserved TLSDESC entry in the PLT for an executable. static const unsigned char tlsdesc_plt_entry[plt_entry_size]; // The .eh_frame unwind information for the PLT. static const int plt_eh_frame_fde_size = 32; static const unsigned char plt_eh_frame_fde[plt_eh_frame_fde_size]; }; template<int size> class Target_x86_64_nacl : public Target_x86_64<size> { public: Target_x86_64_nacl() : Target_x86_64<size>(&x86_64_nacl_info) { } virtual Output_data_plt_x86_64<size>* do_make_data_plt(Layout* layout, Output_data_got<64, false>* got, Output_data_got_plt_x86_64* got_plt, Output_data_space* got_irelative) { return new Output_data_plt_x86_64_nacl<size>(layout, got, got_plt, got_irelative); } virtual Output_data_plt_x86_64<size>* do_make_data_plt(Layout* layout, Output_data_got<64, false>* got, Output_data_got_plt_x86_64* got_plt, Output_data_space* got_irelative, unsigned int plt_count) { return new Output_data_plt_x86_64_nacl<size>(layout, got, got_plt, got_irelative, plt_count); } virtual std::string do_code_fill(section_size_type length) const; private: static const Target::Target_info x86_64_nacl_info; }; template<> const Target::Target_info Target_x86_64_nacl<64>::x86_64_nacl_info = { 64, // size false, // is_big_endian elfcpp::EM_X86_64, // machine_code false, // has_make_symbol false, // has_resolve true, // has_code_fill true, // is_default_stack_executable true, // can_icf_inline_merge_sections '\0', // wrap_char "/lib64/ld-nacl-x86-64.so.1", // dynamic_linker 0x20000, // default_text_segment_address 0x10000, // abi_pagesize (overridable by -z max-page-size) 0x10000, // common_pagesize (overridable by -z common-page-size) true, // isolate_execinstr 0x10000000, // rosegment_gap elfcpp::SHN_UNDEF, // small_common_shndx elfcpp::SHN_X86_64_LCOMMON, // large_common_shndx 0, // small_common_section_flags elfcpp::SHF_X86_64_LARGE, // large_common_section_flags NULL, // attributes_section NULL, // attributes_vendor "_start", // entry_symbol_name 32, // hash_entry_size elfcpp::SHT_X86_64_UNWIND, // unwind_section_type }; template<> const Target::Target_info Target_x86_64_nacl<32>::x86_64_nacl_info = { 32, // size false, // is_big_endian elfcpp::EM_X86_64, // machine_code false, // has_make_symbol false, // has_resolve true, // has_code_fill true, // is_default_stack_executable true, // can_icf_inline_merge_sections '\0', // wrap_char "/lib/ld-nacl-x86-64.so.1", // dynamic_linker 0x20000, // default_text_segment_address 0x10000, // abi_pagesize (overridable by -z max-page-size) 0x10000, // common_pagesize (overridable by -z common-page-size) true, // isolate_execinstr 0x10000000, // rosegment_gap elfcpp::SHN_UNDEF, // small_common_shndx elfcpp::SHN_X86_64_LCOMMON, // large_common_shndx 0, // small_common_section_flags elfcpp::SHF_X86_64_LARGE, // large_common_section_flags NULL, // attributes_section NULL, // attributes_vendor "_start", // entry_symbol_name 32, // hash_entry_size elfcpp::SHT_X86_64_UNWIND, // unwind_section_type }; #define NACLMASK 0xe0 // 32-byte alignment mask. // The first entry in the PLT. template<int size> const unsigned char Output_data_plt_x86_64_nacl<size>::first_plt_entry[plt_entry_size] = { 0xff, 0x35, // pushq contents of memory address 0, 0, 0, 0, // replaced with address of .got + 8 0x4c, 0x8b, 0x1d, // mov GOT+16(%rip), %r11 0, 0, 0, 0, // replaced with address of .got + 16 0x41, 0x83, 0xe3, NACLMASK, // and $-32, %r11d 0x4d, 0x01, 0xfb, // add %r15, %r11 0x41, 0xff, 0xe3, // jmpq *%r11 // 9-byte nop sequence to pad out to the next 32-byte boundary. 0x66, 0x0f, 0x1f, 0x84, 0, 0, 0, 0, 0, // nopw 0x0(%rax,%rax,1) // 32 bytes of nop to pad out to the standard size 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, // excess data32 prefixes 0x2e, 0x0f, 0x1f, 0x84, 0, 0, 0, 0, 0, // nopw %cs:0x0(%rax,%rax,1) 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, // excess data32 prefixes 0x2e, 0x0f, 0x1f, 0x84, 0, 0, 0, 0, 0, // nopw %cs:0x0(%rax,%rax,1) 0x66, // excess data32 prefix 0x90 // nop }; template<int size> void Output_data_plt_x86_64_nacl<size>::do_fill_first_plt_entry( unsigned char* pov, typename elfcpp::Elf_types<size>::Elf_Addr got_address, typename elfcpp::Elf_types<size>::Elf_Addr plt_address) { memcpy(pov, first_plt_entry, plt_entry_size); elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, (got_address + 8 - (plt_address + 2 + 4))); elfcpp::Swap_unaligned<32, false>::writeval(pov + 9, (got_address + 16 - (plt_address + 9 + 4))); } // Subsequent entries in the PLT. template<int size> const unsigned char Output_data_plt_x86_64_nacl<size>::plt_entry[plt_entry_size] = { 0x4c, 0x8b, 0x1d, // mov name@GOTPCREL(%rip),%r11 0, 0, 0, 0, // replaced with address of symbol in .got 0x41, 0x83, 0xe3, NACLMASK, // and $-32, %r11d 0x4d, 0x01, 0xfb, // add %r15, %r11 0x41, 0xff, 0xe3, // jmpq *%r11 // 15-byte nop sequence to pad out to the next 32-byte boundary. 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, // excess data32 prefixes 0x2e, 0x0f, 0x1f, 0x84, 0, 0, 0, 0, 0, // nopw %cs:0x0(%rax,%rax,1) // Lazy GOT entries point here (32-byte aligned). 0x68, // pushq immediate 0, 0, 0, 0, // replaced with index into relocation table 0xe9, // jmp relative 0, 0, 0, 0, // replaced with offset to start of .plt0 // 22 bytes of nop to pad out to the standard size. 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, // excess data32 prefixes 0x2e, 0x0f, 0x1f, 0x84, 0, 0, 0, 0, 0, // nopw %cs:0x0(%rax,%rax,1) 0x0f, 0x1f, 0x80, 0, 0, 0, 0, // nopl 0x0(%rax) }; template<int size> unsigned int Output_data_plt_x86_64_nacl<size>::do_fill_plt_entry( unsigned char* pov, typename elfcpp::Elf_types<size>::Elf_Addr got_address, typename elfcpp::Elf_types<size>::Elf_Addr plt_address, unsigned int got_offset, unsigned int plt_offset, unsigned int plt_index) { memcpy(pov, plt_entry, plt_entry_size); elfcpp::Swap_unaligned<32, false>::writeval(pov + 3, (got_address + got_offset - (plt_address + plt_offset + 3 + 4))); elfcpp::Swap_unaligned<32, false>::writeval(pov + 33, plt_index); elfcpp::Swap_unaligned<32, false>::writeval(pov + 38, - (plt_offset + 38 + 4)); return 32; } // The reserved TLSDESC entry in the PLT. template<int size> const unsigned char Output_data_plt_x86_64_nacl<size>::tlsdesc_plt_entry[plt_entry_size] = { 0xff, 0x35, // pushq x(%rip) 0, 0, 0, 0, // replaced with address of linkmap GOT entry (at PLTGOT + 8) 0x4c, 0x8b, 0x1d, // mov y(%rip),%r11 0, 0, 0, 0, // replaced with offset of reserved TLSDESC_GOT entry 0x41, 0x83, 0xe3, NACLMASK, // and $-32, %r11d 0x4d, 0x01, 0xfb, // add %r15, %r11 0x41, 0xff, 0xe3, // jmpq *%r11 // 41 bytes of nop to pad out to the standard size. 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, // excess data32 prefixes 0x2e, 0x0f, 0x1f, 0x84, 0, 0, 0, 0, 0, // nopw %cs:0x0(%rax,%rax,1) 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, // excess data32 prefixes 0x2e, 0x0f, 0x1f, 0x84, 0, 0, 0, 0, 0, // nopw %cs:0x0(%rax,%rax,1) 0x66, 0x66, // excess data32 prefixes 0x2e, 0x0f, 0x1f, 0x84, 0, 0, 0, 0, 0, // nopw %cs:0x0(%rax,%rax,1) }; template<int size> void Output_data_plt_x86_64_nacl<size>::do_fill_tlsdesc_entry( unsigned char* pov, typename elfcpp::Elf_types<size>::Elf_Addr got_address, typename elfcpp::Elf_types<size>::Elf_Addr plt_address, typename elfcpp::Elf_types<size>::Elf_Addr got_base, unsigned int tlsdesc_got_offset, unsigned int plt_offset) { memcpy(pov, tlsdesc_plt_entry, plt_entry_size); elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, (got_address + 8 - (plt_address + plt_offset + 2 + 4))); elfcpp::Swap_unaligned<32, false>::writeval(pov + 9, (got_base + tlsdesc_got_offset - (plt_address + plt_offset + 9 + 4))); } // The .eh_frame unwind information for the PLT. template<int size> const unsigned char Output_data_plt_x86_64_nacl<size>::plt_eh_frame_fde[plt_eh_frame_fde_size] = { 0, 0, 0, 0, // Replaced with offset to .plt. 0, 0, 0, 0, // Replaced with size of .plt. 0, // Augmentation size. elfcpp::DW_CFA_def_cfa_offset, 16, // DW_CFA_def_cfa_offset: 16. elfcpp::DW_CFA_advance_loc + 6, // Advance 6 to __PLT__ + 6. elfcpp::DW_CFA_def_cfa_offset, 24, // DW_CFA_def_cfa_offset: 24. elfcpp::DW_CFA_advance_loc + 58, // Advance 58 to __PLT__ + 64. elfcpp::DW_CFA_def_cfa_expression, // DW_CFA_def_cfa_expression. 13, // Block length. elfcpp::DW_OP_breg7, 8, // Push %rsp + 8. elfcpp::DW_OP_breg16, 0, // Push %rip. elfcpp::DW_OP_const1u, 63, // Push 0x3f. elfcpp::DW_OP_and, // & (%rip & 0x3f). elfcpp::DW_OP_const1u, 37, // Push 0x25. elfcpp::DW_OP_ge, // >= ((%rip & 0x3f) >= 0x25) elfcpp::DW_OP_lit3, // Push 3. elfcpp::DW_OP_shl, // << (((%rip & 0x3f) >= 0x25) << 3) elfcpp::DW_OP_plus, // + ((((%rip&0x3f)>=0x25)<<3)+%rsp+8 elfcpp::DW_CFA_nop, // Align to 32 bytes. elfcpp::DW_CFA_nop }; // Return a string used to fill a code section with nops. // For NaCl, long NOPs are only valid if they do not cross // bundle alignment boundaries, so keep it simple with one-byte NOPs. template<int size> std::string Target_x86_64_nacl<size>::do_code_fill(section_size_type length) const { return std::string(length, static_cast<char>(0x90)); } // The selector for x86_64-nacl object files. template<int size> class Target_selector_x86_64_nacl : public Target_selector_nacl<Target_selector_x86_64<size>, Target_x86_64_nacl<size> > { public: Target_selector_x86_64_nacl() : Target_selector_nacl<Target_selector_x86_64<size>, Target_x86_64_nacl<size> >("x86-64", size == 64 ? "elf64-x86-64-nacl" : "elf32-x86-64-nacl", size == 64 ? "elf_x86_64_nacl" : "elf32_x86_64_nacl") { } }; Target_selector_x86_64_nacl<64> target_selector_x86_64; Target_selector_x86_64_nacl<32> target_selector_x32; } // End anonymous namespace.