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// x86_64.cc -- x86_64 target support for gold. // Copyright 2006, 2007, 2008, 2009 Free Software Foundation, Inc. // Written by Ian Lance Taylor <iant@google.com>. // This file is part of gold. // This program is free software; you can redistribute it and/or modify // it under the terms of the GNU General Public License as published by // the Free Software Foundation; either version 3 of the License, or // (at your option) any later version. // This program is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // You should have received a copy of the GNU General Public License // along with this program; if not, write to the Free Software // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, // MA 02110-1301, USA. #include "gold.h" #include <cstring> #include "elfcpp.h" #include "parameters.h" #include "reloc.h" #include "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 "gc.h" namespace { using namespace gold; class Output_data_plt_x86_64; // 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 class Target_x86_64 : public Target_freebsd<64, 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, 64, false> Reloc_section; Target_x86_64() : Target_freebsd<64, false>(&x86_64_info), got_(NULL), plt_(NULL), got_plt_(NULL), rela_dyn_(NULL), copy_relocs_(elfcpp::R_X86_64_COPY), dynbss_(NULL), got_mod_index_offset_(-1U), tls_base_symbol_defined_(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(const General_options& options, Symbol_table* symtab, Layout* layout, Sized_relobj<64, 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(const General_options& options, Symbol_table* symtab, Layout* layout, Sized_relobj<64, false>* object, unsigned int data_shndx, unsigned int sh_type, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, bool needs_special_offset_handling, size_t local_symbol_count, const unsigned char* plocal_symbols); // Finalize the sections. void do_finalize_sections(Layout*); // Return the value to use for a dynamic which requires special // treatment. uint64_t do_dynsym_value(const Symbol*) const; // Relocate a section. void relocate_section(const Relocate_info<64, false>*, unsigned int sh_type, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, bool needs_special_offset_handling, unsigned char* view, elfcpp::Elf_types<64>::Elf_Addr view_address, section_size_type view_size, const Reloc_symbol_changes*); // Scan the relocs during a relocatable link. void scan_relocatable_relocs(const General_options& options, Symbol_table* symtab, Layout* layout, Sized_relobj<64, false>* object, unsigned int data_shndx, unsigned int sh_type, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, bool needs_special_offset_handling, size_t local_symbol_count, const unsigned char* plocal_symbols, Relocatable_relocs*); // Relocate a section during a relocatable link. void relocate_for_relocatable(const Relocate_info<64, false>*, unsigned int sh_type, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, off_t offset_in_output_section, const Relocatable_relocs*, unsigned char* view, elfcpp::Elf_types<64>::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; } // Adjust -fstack-split code which calls non-stack-split code. void do_calls_non_split(Relobj* object, unsigned int shndx, section_offset_type fnoffset, section_size_type fnsize, unsigned char* view, section_size_type view_size, std::string* from, std::string* to) const; // Return the size of the GOT section. section_size_type got_size() { gold_assert(this->got_ != NULL); return this->got_->data_size(); } private: // The class which scans relocations. class Scan { public: Scan() : issued_non_pic_error_(false) { } inline void local(const General_options& options, Symbol_table* symtab, Layout* layout, Target_x86_64* target, Sized_relobj<64, false>* object, unsigned int data_shndx, Output_section* output_section, const elfcpp::Rela<64, false>& reloc, unsigned int r_type, const elfcpp::Sym<64, false>& lsym); inline void global(const General_options& options, Symbol_table* symtab, Layout* layout, Target_x86_64* target, Sized_relobj<64, false>* object, unsigned int data_shndx, Output_section* output_section, const elfcpp::Rela<64, false>& reloc, unsigned int r_type, Symbol* gsym); private: static void unsupported_reloc_local(Sized_relobj<64, false>*, unsigned int r_type); static void unsupported_reloc_global(Sized_relobj<64, false>*, unsigned int r_type, Symbol*); void check_non_pic(Relobj*, 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), saw_tls_block_reloc_(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<64, false>*, Target_x86_64*, Output_section*, size_t relnum, const elfcpp::Rela<64, false>&, unsigned int r_type, const Sized_symbol<64>*, const Symbol_value<64>*, unsigned char*, elfcpp::Elf_types<64>::Elf_Addr, section_size_type); private: // Do a TLS relocation. inline void relocate_tls(const Relocate_info<64, false>*, Target_x86_64*, size_t relnum, const elfcpp::Rela<64, false>&, unsigned int r_type, const Sized_symbol<64>*, const Symbol_value<64>*, unsigned char*, elfcpp::Elf_types<64>::Elf_Addr, section_size_type); // Do a TLS General-Dynamic to Initial-Exec transition. inline void tls_gd_to_ie(const Relocate_info<64, false>*, size_t relnum, Output_segment* tls_segment, const elfcpp::Rela<64, false>&, unsigned int r_type, elfcpp::Elf_types<64>::Elf_Addr value, unsigned char* view, elfcpp::Elf_types<64>::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<64, false>*, size_t relnum, Output_segment* tls_segment, const elfcpp::Rela<64, false>&, unsigned int r_type, elfcpp::Elf_types<64>::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<64, false>*, size_t relnum, Output_segment* tls_segment, const elfcpp::Rela<64, false>&, unsigned int r_type, elfcpp::Elf_types<64>::Elf_Addr value, unsigned char* view, elfcpp::Elf_types<64>::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<64, false>*, size_t relnum, Output_segment* tls_segment, const elfcpp::Rela<64, false>&, unsigned int r_type, elfcpp::Elf_types<64>::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<64, false>*, size_t relnum, Output_segment* tls_segment, const elfcpp::Rela<64, false>&, unsigned int r_type, elfcpp::Elf_types<64>::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<64, false>*, size_t relnum, Output_segment* tls_segment, const elfcpp::Rela<64, false>&, unsigned int r_type, elfcpp::Elf_types<64>::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_; // This is set if we see a relocation which could load the address // of the TLS block. Whether we see such a relocation determines // how we handle the R_X86_64_DTPOFF32 relocation, which is used // in debugging sections. bool saw_tls_block_reloc_; }; // A class which returns the size required for a relocation type, // used while scanning relocs during a relocatable link. class Relocatable_size_for_reloc { public: unsigned int get_size_for_reloc(unsigned int, Relobj*); }; // Adjust TLS relocation type based on the options and whether this // is a local symbol. static tls::Tls_optimization optimize_tls_reloc(bool is_final, int r_type); // Get the GOT section, creating it if necessary. Output_data_got<64, false>* got_section(Symbol_table*, Layout*); // Get the GOT PLT section. Output_data_space* got_plt_section() const { gold_assert(this->got_plt_ != NULL); return this->got_plt_; } // Create 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*); // 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<64, false>* object); // Get the PLT section. Output_data_plt_x86_64* 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*); // Add a potential copy relocation. void copy_reloc(Symbol_table* symtab, Layout* layout, Sized_relobj<64, false>* object, unsigned int shndx, Output_section* output_section, Symbol* sym, const elfcpp::Rela<64, false>& reloc) { this->copy_relocs_.copy_reloc(symtab, layout, symtab->get_sized_symbol<64>(sym), object, shndx, output_section, reloc, this->rela_dyn_section(layout)); } // Information about this specific target which we pass to the // general Target structure. static const Target::Target_info x86_64_info; 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 }; // The GOT section. Output_data_got<64, false>* got_; // The PLT section. Output_data_plt_x86_64* plt_; // The GOT PLT section. Output_data_space* got_plt_; // The dynamic reloc section. Reloc_section* rela_dyn_; // Relocs saved to avoid a COPY reloc. Copy_relocs<elfcpp::SHT_RELA, 64, false> copy_relocs_; // Space for variables copied with a COPY reloc. Output_data_space* dynbss_; // Offset of the GOT entry for the TLS module index. unsigned int got_mod_index_offset_; // True if the _TLS_MODULE_BASE_ symbol has been defined. bool tls_base_symbol_defined_; }; const Target::Target_info Target_x86_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 '\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) 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 }; // This is called when a new output section is created. This is where // we handle the SHF_X86_64_LARGE. void Target_x86_64::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. Output_data_got<64, false>* Target_x86_64::got_section(Symbol_table* symtab, Layout* layout) { if (this->got_ == NULL) { gold_assert(symtab != NULL && layout != NULL); this->got_ = new Output_data_got<64, false>(); Output_section* os; os = layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS, (elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE), this->got_, false); os->set_is_relro(); // The old GNU linker creates a .got.plt section. We just // create another set of data in the .got section. Note that we // always create a PLT if we create a GOT, although the PLT // might be empty. this->got_plt_ = new Output_data_space(8, "** GOT PLT"); os = layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS, (elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE), this->got_plt_, false); os->set_is_relro(); // The first three entries are reserved. this->got_plt_->set_current_data_size(3 * 8); // Define _GLOBAL_OFFSET_TABLE_ at the start of the PLT. symtab->define_in_output_data("_GLOBAL_OFFSET_TABLE_", NULL, this->got_plt_, 0, 0, elfcpp::STT_OBJECT, elfcpp::STB_LOCAL, elfcpp::STV_HIDDEN, 0, false, false); } return this->got_; } // Get the dynamic reloc section, creating it if necessary. Target_x86_64::Reloc_section* Target_x86_64::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_, true); } return this->rela_dyn_; } // A class to handle the PLT data. class Output_data_plt_x86_64 : public Output_section_data { public: typedef Output_data_reloc<elfcpp::SHT_RELA, true, 64, false> Reloc_section; Output_data_plt_x86_64(Layout*, Output_data_got<64, false>*, Output_data_space*); // Add an entry to the PLT. void add_entry(Symbol* gsym); // 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_ + 1) * plt_entry_size; } // Return the .rel.plt section data. const Reloc_section* rel_plt() const { return this->rel_; } protected: void do_adjust_output_section(Output_section* os); // Write to a map file. void do_print_to_mapfile(Mapfile* mapfile) const { mapfile->print_output_data(this, _("** PLT")); } private: // The size of an entry in the PLT. static const int plt_entry_size = 16; // The first entry in the PLT. // From the AMD64 ABI: "Unlike Intel386 ABI, this ABI uses the same // procedure linkage table for both programs and shared objects." static unsigned char first_plt_entry[plt_entry_size]; // Other entries in the PLT for an executable. static unsigned char plt_entry[plt_entry_size]; // The reserved TLSDESC entry in the PLT for an executable. static unsigned char tlsdesc_plt_entry[plt_entry_size]; // 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 .got section. Output_data_got<64, false>* got_; // The .got.plt section. Output_data_space* got_plt_; // The number of PLT entries. unsigned int count_; // Offset of the reserved TLSDESC_GOT entry when needed. unsigned int tlsdesc_got_offset_; }; // Create the PLT section. The ordinary .got section is an argument, // since we need to refer to the start. We also create our own .got // section just for PLT entries. Output_data_plt_x86_64::Output_data_plt_x86_64(Layout* layout, Output_data_got<64, false>* got, Output_data_space* got_plt) : Output_section_data(8), got_(got), got_plt_(got_plt), count_(0), tlsdesc_got_offset_(-1U) { this->rel_ = new Reloc_section(false); layout->add_output_section_data(".rela.plt", elfcpp::SHT_RELA, elfcpp::SHF_ALLOC, this->rel_, true); } void Output_data_plt_x86_64::do_adjust_output_section(Output_section* os) { os->set_entsize(plt_entry_size); } // Add an entry to the PLT. void Output_data_plt_x86_64::add_entry(Symbol* gsym) { gold_assert(!gsym->has_plt_offset()); // Note that when setting the PLT offset we skip the initial // reserved PLT entry. gsym->set_plt_offset((this->count_ + 1) * plt_entry_size); ++this->count_; section_offset_type got_offset = this->got_plt_->current_data_size(); // Every PLT entry needs a GOT entry which points back to the PLT // entry (this will be changed by the dynamic linker, normally // lazily when the function is called). this->got_plt_->set_current_data_size(got_offset + 8); // Every PLT entry needs a reloc. gsym->set_needs_dynsym_entry(); this->rel_->add_global(gsym, elfcpp::R_X86_64_JUMP_SLOT, this->got_plt_, got_offset, 0); // 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. } // Set the final size. void Output_data_plt_x86_64::set_final_data_size() { unsigned int count = this->count_; if (this->has_tlsdesc_entry()) ++count; this->set_data_size((count + 1) * plt_entry_size); } // The first entry in the PLT for an executable. unsigned char Output_data_plt_x86_64::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) }; // Subsequent entries in the PLT for an executable. unsigned char Output_data_plt_x86_64::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 }; // The reserved TLSDESC entry in the PLT for an executable. unsigned char Output_data_plt_x86_64::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 }; // Write out the PLT. This uses the hand-coded instructions above, // and adjusts them as needed. This is specified by the AMD64 ABI. void Output_data_plt_x86_64::do_write(Output_file* of) { const off_t offset = this->offset(); const section_size_type oview_size = convert_to_section_size_type(this->data_size()); unsigned char* const oview = of->get_output_view(offset, oview_size); const off_t got_file_offset = this->got_plt_->offset(); const section_size_type got_size = convert_to_section_size_type(this->got_plt_->data_size()); unsigned char* const got_view = of->get_output_view(got_file_offset, got_size); unsigned char* pov = oview; // 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 = 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. elfcpp::Elf_types<64>::Elf_Addr got_address = this->got_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))); pov += plt_entry_size; unsigned char* got_pov = got_view; memset(got_pov, 0, 24); got_pov += 24; unsigned int plt_offset = plt_entry_size; unsigned int got_offset = 24; const unsigned int count = this->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. memcpy(pov, plt_entry, plt_entry_size); elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, (got_address + got_offset - (plt_address + plt_offset + 6))); elfcpp::Swap_unaligned<32, false>::writeval(pov + 7, plt_index); elfcpp::Swap<32, false>::writeval(pov + 12, - (plt_offset + plt_entry_size)); // Set the entry in the GOT. elfcpp::Swap<64, false>::writeval(got_pov, plt_address + plt_offset + 6); } if (this->has_tlsdesc_entry()) { // Set and adjust the reserved TLSDESC PLT entry. unsigned int tlsdesc_got_offset = this->get_tlsdesc_got_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))); pov += 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); } // Create the PLT section. void Target_x86_64::make_plt_section(Symbol_table* symtab, Layout* layout) { if (this->plt_ == NULL) { // Create the GOT sections first. this->got_section(symtab, layout); this->plt_ = new Output_data_plt_x86_64(layout, this->got_, this->got_plt_); layout->add_output_section_data(".plt", elfcpp::SHT_PROGBITS, (elfcpp::SHF_ALLOC | elfcpp::SHF_EXECINSTR), this->plt_, false); } } // Create a PLT entry for a global symbol. void Target_x86_64::make_plt_entry(Symbol_table* symtab, Layout* layout, Symbol* gsym) { if (gsym->has_plt_offset()) return; if (this->plt_ == NULL) this->make_plt_section(symtab, layout); this->plt_->add_entry(gsym); } // Define the _TLS_MODULE_BASE_ symbol in the TLS segment. void Target_x86_64::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, 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. void Target_x86_64::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. unsigned int Target_x86_64::got_mod_index_entry(Symbol_table* symtab, Layout* layout, Sized_relobj<64, 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. tls::Tls_optimization Target_x86_64::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(); } } // Report an unsupported relocation against a local symbol. void Target_x86_64::Scan::unsupported_reloc_local(Sized_relobj<64, 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. void Target_x86_64::Scan::check_non_pic(Relobj* object, unsigned int r_type) { switch (r_type) { // These are the relocation types supported by glibc for x86_64. case elfcpp::R_X86_64_RELATIVE: 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_32: case elfcpp::R_X86_64_PC32: case elfcpp::R_X86_64_COPY: 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; " "recompile with -fPIC")); this->issued_non_pic_error_ = true; return; case elfcpp::R_X86_64_NONE: gold_unreachable(); } } // Scan a relocation for a local symbol. inline void Target_x86_64::Scan::local(const General_options&, Symbol_table* symtab, Layout* layout, Target_x86_64* target, Sized_relobj<64, false>* object, unsigned int data_shndx, Output_section* output_section, const elfcpp::Rela<64, false>& reloc, unsigned int r_type, const elfcpp::Sym<64, false>& lsym) { switch (r_type) { case elfcpp::R_X86_64_NONE: case elfcpp::R_386_GNU_VTINHERIT: case elfcpp::R_386_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<64>(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()); } 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()) { this->check_non_pic(object, r_type); Reloc_section* rela_dyn = target->rela_dyn_section(layout); unsigned int r_sym = elfcpp::elf_r_sym<64>(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_PC16: case elfcpp::R_X86_64_PC8: break; case elfcpp::R_X86_64_PLT32: // 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_GOTPLT64: { // The symbol requires a GOT entry. Output_data_got<64, false>* got = target->got_section(symtab, layout); unsigned int r_sym = elfcpp::elf_r_sym<64>(reloc.get_r_info()); if (got->add_local(object, r_sym, GOT_TYPE_STANDARD)) { // 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) rela_dyn->add_local_relative( object, r_sym, elfcpp::R_X86_64_RELATIVE, got, object->local_got_offset(r_sym, GOT_TYPE_STANDARD), 0); else { this->check_non_pic(object, r_type); 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: // 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::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<64>(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_rela(object, r_sym, shndx, GOT_TYPE_TLS_PAIR, target->rela_dyn_section(layout), elfcpp::R_X86_64_DTPMOD64, 0); } 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. Output_data_got<64, false>* got = target->got_section(symtab, layout); unsigned int r_sym = elfcpp::elf_r_sym<64>(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_rela(object, r_sym, shndx, GOT_TYPE_TLS_DESC, target->rela_dyn_section(layout), elfcpp::R_X86_64_TLSDESC, 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<64>(reloc.get_r_info()); got->add_local_with_rela(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. void Target_x86_64::Scan::unsupported_reloc_global(Sized_relobj<64, false>* object, unsigned int r_type, Symbol* gsym) { gold_error(_("%s: unsupported reloc %u against global symbol %s"), object->name().c_str(), r_type, gsym->demangled_name().c_str()); } // Scan a relocation for a global symbol. inline void Target_x86_64::Scan::global(const General_options&, Symbol_table* symtab, Layout* layout, Target_x86_64* target, Sized_relobj<64, false>* object, unsigned int data_shndx, Output_section* output_section, const elfcpp::Rela<64, false>& reloc, unsigned int r_type, Symbol* gsym) { switch (r_type) { case elfcpp::R_X86_64_NONE: case elfcpp::R_386_GNU_VTINHERIT: case elfcpp::R_386_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(Symbol::ABSOLUTE_REF)) { if (gsym->may_need_copy_reloc()) { target->copy_reloc(symtab, layout, object, data_shndx, output_section, gsym, reloc); } else if (r_type == elfcpp::R_X86_64_64 && 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()); } else { this->check_non_pic(object, r_type); 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_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. int flags = Symbol::NON_PIC_REF; if (gsym->type() == elfcpp::STT_FUNC) flags |= Symbol::FUNCTION_CALL; if (gsym->needs_dynamic_reloc(flags)) { if (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); 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_GOTPLT64: { // The symbol requires a GOT entry. Output_data_got<64, false>* got = target->got_section(symtab, layout); if (gsym->final_value_is_known()) 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); if (gsym->is_from_dynobj() || gsym->is_undefined() || gsym->is_preemptible()) got->add_global_with_rela(gsym, GOT_TYPE_STANDARD, rela_dyn, elfcpp::R_X86_64_GLOB_DAT); else { if (got->add_global(gsym, GOT_TYPE_STANDARD)) rela_dyn->add_global_relative( gsym, elfcpp::R_X86_64_RELATIVE, got, gsym->got_offset(GOT_TYPE_STANDARD), 0); } } // For GOTPLT64, we also need a PLT entry (but only if the // symbol is not fully resolved). if (r_type == elfcpp::R_X86_64_GOTPLT64 && !gsym->final_value_is_known()) target->make_plt_entry(symtab, layout, gsym); } break; case elfcpp::R_X86_64_PLT32: // If the symbol is fully resolved, this is just a PC32 reloc. // Otherwise we need a PLT entry. if (gsym->final_value_is_known()) break; // If building a shared library, we can also skip the PLT entry // if the symbol is defined in the output file and is protected // or hidden. if (gsym->is_defined() && !gsym->is_from_dynobj() && !gsym->is_preemptible()) break; target->make_plt_entry(symtab, layout, gsym); break; case elfcpp::R_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: // 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 { const bool is_final = gsym->final_value_is_known(); const tls::Tls_optimization optimized_type = Target_x86_64::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_rela(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_rela(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. Output_data_got<64, false>* got = target->got_section(symtab, layout); got->add_global_pair_with_rela(gsym, GOT_TYPE_TLS_DESC, target->rela_dyn_section(layout), 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_rela(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_rela(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_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 global symbol %s"), object->name().c_str(), r_type, gsym->demangled_name().c_str()); break; } } void Target_x86_64::gc_process_relocs(const General_options& options, Symbol_table* symtab, Layout* layout, Sized_relobj<64, false>* object, unsigned int data_shndx, unsigned int sh_type, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, bool needs_special_offset_handling, size_t local_symbol_count, const unsigned char* plocal_symbols) { if (sh_type == elfcpp::SHT_REL) { return; } gold::gc_process_relocs<64, false, Target_x86_64, elfcpp::SHT_RELA, Target_x86_64::Scan>( options, symtab, layout, this, object, data_shndx, prelocs, reloc_count, output_section, needs_special_offset_handling, local_symbol_count, plocal_symbols); } // Scan relocations for a section. void Target_x86_64::scan_relocs(const General_options& options, Symbol_table* symtab, Layout* layout, Sized_relobj<64, false>* object, unsigned int data_shndx, unsigned int sh_type, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, bool needs_special_offset_handling, size_t local_symbol_count, const unsigned char* plocal_symbols) { if (sh_type == elfcpp::SHT_REL) { gold_error(_("%s: unsupported REL reloc section"), object->name().c_str()); return; } gold::scan_relocs<64, false, Target_x86_64, elfcpp::SHT_RELA, Target_x86_64::Scan>( options, symtab, layout, this, object, data_shndx, prelocs, reloc_count, output_section, needs_special_offset_handling, local_symbol_count, plocal_symbols); } // Finalize the sections. void Target_x86_64::do_finalize_sections(Layout* layout) { // Fill in some more dynamic tags. Output_data_dynamic* const odyn = layout->dynamic_data(); if (odyn != NULL) { if (this->got_plt_ != NULL && this->got_plt_->output_section() != NULL) odyn->add_section_address(elfcpp::DT_PLTGOT, this->got_plt_); if (this->plt_ != NULL && this->plt_->output_section() != NULL) { const Output_data* od = this->plt_->rel_plt(); odyn->add_section_size(elfcpp::DT_PLTRELSZ, od); odyn->add_section_address(elfcpp::DT_JMPREL, od); odyn->add_constant(elfcpp::DT_PLTREL, elfcpp::DT_RELA); if (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); } } if (this->rela_dyn_ != NULL && this->rela_dyn_->output_section() != NULL) { const Output_data* od = this->rela_dyn_; odyn->add_section_address(elfcpp::DT_RELA, od); odyn->add_section_size(elfcpp::DT_RELASZ, od); odyn->add_constant(elfcpp::DT_RELAENT, elfcpp::Elf_sizes<64>::rela_size); } if (!parameters->options().shared()) { // The value of the DT_DEBUG tag is filled in by the dynamic // linker at run time, and used by the debugger. odyn->add_constant(elfcpp::DT_DEBUG, 0); } } // Emit any relocs we saved in an attempt to avoid generating COPY // relocs. if (this->copy_relocs_.any_saved_relocs()) this->copy_relocs_.emit(this->rela_dyn_section(layout)); } // Perform a relocation. inline bool Target_x86_64::Relocate::relocate(const Relocate_info<64, false>* relinfo, Target_x86_64* target, Output_section*, size_t relnum, const elfcpp::Rela<64, false>& rela, unsigned int r_type, const Sized_symbol<64>* gsym, const Symbol_value<64>* psymval, unsigned char* view, elfcpp::Elf_types<64>::Elf_Addr address, section_size_type view_size) { if (this->skip_call_tls_get_addr_) { if ((r_type != elfcpp::R_X86_64_PLT32 && 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")); } else { this->skip_call_tls_get_addr_ = false; return false; } } // Pick the value to use for symbols defined in shared objects. Symbol_value<64> symval; if (gsym != NULL && gsym->use_plt_offset(r_type == elfcpp::R_X86_64_PC64 || r_type == elfcpp::R_X86_64_PC32 || r_type == elfcpp::R_X86_64_PC16 || r_type == elfcpp::R_X86_64_PC8)) { symval.set_output_value(target->plt_section()->address() + gsym->plt_offset()); psymval = &symval; } const Sized_relobj<64, false>* object = relinfo->object; 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; unsigned 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_GOTPCREL: 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<64>(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; } switch (r_type) { case elfcpp::R_X86_64_NONE: case elfcpp::R_386_GNU_VTINHERIT: case elfcpp::R_386_GNU_VTENTRY: break; case elfcpp::R_X86_64_64: Relocate_functions<64, false>::rela64(view, object, psymval, addend); break; case elfcpp::R_X86_64_PC64: Relocate_functions<64, false>::pcrela64(view, object, psymval, addend, address); break; case elfcpp::R_X86_64_32: // FIXME: we need to verify that value + addend fits into 32 bits: // uint64_t x = value + addend; // x == static_cast<uint64_t>(static_cast<uint32_t>(x)) // Likewise for other <=32-bit relocations (but see R_X86_64_32S). Relocate_functions<64, false>::rela32(view, object, psymval, addend); break; case elfcpp::R_X86_64_32S: // FIXME: we need to verify that value + addend fits into 32 bits: // int64_t x = value + addend; // note this quantity is signed! // x == static_cast<int64_t>(static_cast<int32_t>(x)) Relocate_functions<64, false>::rela32(view, object, psymval, addend); break; case elfcpp::R_X86_64_PC32: Relocate_functions<64, false>::pcrela32(view, object, psymval, addend, address); break; case elfcpp::R_X86_64_16: Relocate_functions<64, false>::rela16(view, object, psymval, addend); break; case elfcpp::R_X86_64_PC16: Relocate_functions<64, false>::pcrela16(view, object, psymval, addend, address); break; case elfcpp::R_X86_64_8: Relocate_functions<64, false>::rela8(view, object, psymval, addend); break; case elfcpp::R_X86_64_PC8: Relocate_functions<64, false>::pcrela8(view, object, psymval, addend, address); break; case elfcpp::R_X86_64_PLT32: 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(). Relocate_functions<64, false>::pcrela32(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()); elfcpp::Elf_types<64>::Elf_Addr got_address; got_address = target->got_section(NULL, NULL)->address(); Relocate_functions<64, false>::rela64(view, object, psymval, addend - got_address); } case elfcpp::R_X86_64_GOT32: gold_assert(have_got_offset); Relocate_functions<64, false>::rela32(view, got_offset, addend); break; case elfcpp::R_X86_64_GOTPC32: { gold_assert(gsym); elfcpp::Elf_types<64>::Elf_Addr value; value = target->got_plt_section()->address(); Relocate_functions<64, false>::pcrela32(view, value, addend, address); } break; case elfcpp::R_X86_64_GOT64: // The ABI doc says "Like GOT64, but indicates a PLT entry is needed." // Since we always add a PLT entry, this is equivalent. case elfcpp::R_X86_64_GOTPLT64: gold_assert(have_got_offset); Relocate_functions<64, false>::rela64(view, got_offset, addend); break; case elfcpp::R_X86_64_GOTPC64: { gold_assert(gsym); elfcpp::Elf_types<64>::Elf_Addr value; value = target->got_plt_section()->address(); Relocate_functions<64, false>::pcrela64(view, value, addend, address); } break; case elfcpp::R_X86_64_GOTOFF64: { elfcpp::Elf_types<64>::Elf_Addr value; value = (psymval->value(object, 0) - target->got_plt_section()->address()); Relocate_functions<64, false>::rela64(view, value, addend); } break; case elfcpp::R_X86_64_GOTPCREL: { gold_assert(have_got_offset); elfcpp::Elf_types<64>::Elf_Addr value; value = target->got_plt_section()->address() + got_offset; Relocate_functions<64, false>::pcrela32(view, value, addend, address); } break; case elfcpp::R_X86_64_GOTPCREL64: { gold_assert(have_got_offset); elfcpp::Elf_types<64>::Elf_Addr value; value = target->got_plt_section()->address() + got_offset; Relocate_functions<64, false>::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: // 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; } return true; } // Perform a TLS relocation. inline void Target_x86_64::Relocate::relocate_tls(const Relocate_info<64, false>* relinfo, Target_x86_64* target, size_t relnum, const elfcpp::Rela<64, false>& rela, unsigned int r_type, const Sized_symbol<64>* gsym, const Symbol_value<64>* psymval, unsigned char* view, elfcpp::Elf_types<64>::Elf_Addr address, section_size_type view_size) { Output_segment* tls_segment = relinfo->layout->tls_segment(); const Sized_relobj<64, false>* object = relinfo->object; const elfcpp::Elf_Xword addend = rela.get_r_addend(); elfcpp::Elf_types<64>::Elf_Addr value = psymval->value(relinfo->object, 0); const bool is_final = (gsym == NULL ? !parameters->options().output_is_position_independent() : gsym->final_value_is_known()); const tls::Tls_optimization optimized_type = Target_x86_64::optimize_tls_reloc(is_final, r_type); switch (r_type) { case elfcpp::R_X86_64_TLSGD: // Global-dynamic this->saw_tls_block_reloc_ = true; if (optimized_type == tls::TLSOPT_TO_LE) { gold_assert(tls_segment != NULL); 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<64>(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) { gold_assert(tls_segment != NULL); value = target->got_plt_section()->address() + got_offset; this->tls_gd_to_ie(relinfo, relnum, tls_segment, 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<64, 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: this->saw_tls_block_reloc_ = true; if (optimized_type == tls::TLSOPT_TO_LE) { gold_assert(tls_segment != NULL); 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; 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<64>(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) { gold_assert(tls_segment != NULL); value = target->got_plt_section()->address() + got_offset; this->tls_desc_gd_to_ie(relinfo, relnum, tls_segment, 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<64, 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 this->saw_tls_block_reloc_ = true; if (optimized_type == tls::TLSOPT_TO_LE) { gold_assert(tls_segment != NULL); 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<64, 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: if (optimized_type == tls::TLSOPT_TO_LE) { // This relocation type is used in debugging information. // In that case we need to not optimize the value. If we // haven't seen a TLSLD reloc, then we assume we should not // optimize this reloc. if (this->saw_tls_block_reloc_) { gold_assert(tls_segment != NULL); value -= tls_segment->memsz(); } } Relocate_functions<64, false>::rela32(view, value, addend); break; case elfcpp::R_X86_64_DTPOFF64: if (optimized_type == tls::TLSOPT_TO_LE) { // See R_X86_64_DTPOFF32, just above, for why we test this. if (this->saw_tls_block_reloc_) { gold_assert(tls_segment != NULL); value -= tls_segment->memsz(); } } Relocate_functions<64, false>::rela64(view, value, addend); break; case elfcpp::R_X86_64_GOTTPOFF: // Initial-exec if (optimized_type == tls::TLSOPT_TO_LE) { gold_assert(tls_segment != NULL); Target_x86_64::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<64>(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<64, 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 value -= tls_segment->memsz(); Relocate_functions<64, false>::rela32(view, value, addend); break; } } // Do a relocation in which we convert a TLS General-Dynamic to an // Initial-Exec. inline void Target_x86_64::Relocate::tls_gd_to_ie(const Relocate_info<64, false>* relinfo, size_t relnum, Output_segment*, const elfcpp::Rela<64, false>& rela, unsigned int, elfcpp::Elf_types<64>::Elf_Addr value, unsigned char* view, elfcpp::Elf_types<64>::Elf_Addr address, section_size_type view_size) { // .byte 0x66; leaq foo@tlsgd(%rip),%rdi; // .word 0x6666; rex64; call __tls_get_addr // ==> movq %fs:0,%rax; addq x@gottpoff(%rip),%rax tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -4); 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\x48\x8d\x3d", 4) == 0)); tls::check_tls(relinfo, relnum, rela.get_r_offset(), (memcmp(view + 4, "\x66\x66\x48\xe8", 4) == 0)); memcpy(view - 4, "\x64\x48\x8b\x04\x25\0\0\0\0\x48\x03\x05\0\0\0\0", 16); const elfcpp::Elf_Xword addend = rela.get_r_addend(); Relocate_functions<64, 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. inline void Target_x86_64::Relocate::tls_gd_to_le(const Relocate_info<64, false>* relinfo, size_t relnum, Output_segment* tls_segment, const elfcpp::Rela<64, false>& rela, unsigned int, elfcpp::Elf_types<64>::Elf_Addr value, unsigned char* view, section_size_type view_size) { // .byte 0x66; leaq foo@tlsgd(%rip),%rdi; // .word 0x6666; rex64; call __tls_get_addr // ==> movq %fs:0,%rax; leaq x@tpoff(%rax),%rax tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -4); 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\x48\x8d\x3d", 4) == 0)); tls::check_tls(relinfo, relnum, rela.get_r_offset(), (memcmp(view + 4, "\x66\x66\x48\xe8", 4) == 0)); memcpy(view - 4, "\x64\x48\x8b\x04\x25\0\0\0\0\x48\x8d\x80\0\0\0\0", 16); value -= tls_segment->memsz(); Relocate_functions<64, 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. inline void Target_x86_64::Relocate::tls_desc_gd_to_ie( const Relocate_info<64, false>* relinfo, size_t relnum, Output_segment*, const elfcpp::Rela<64, false>& rela, unsigned int r_type, elfcpp::Elf_types<64>::Elf_Addr value, unsigned char* view, elfcpp::Elf_types<64>::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<64, 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. inline void Target_x86_64::Relocate::tls_desc_gd_to_le( const Relocate_info<64, false>* relinfo, size_t relnum, Output_segment* tls_segment, const elfcpp::Rela<64, false>& rela, unsigned int r_type, elfcpp::Elf_types<64>::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<64, 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; } } inline void Target_x86_64::Relocate::tls_ld_to_le(const Relocate_info<64, false>* relinfo, size_t relnum, Output_segment*, const elfcpp::Rela<64, false>& rela, unsigned int, elfcpp::Elf_types<64>::Elf_Addr, unsigned char* view, section_size_type view_size) { // leaq foo@tlsld(%rip),%rdi; call __tls_get_addr@plt; // ... leq foo@dtpoff(%rax),%reg // ==> .word 0x6666; .byte 0x66; movq %fs:0,%rax ... 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); memcpy(view - 3, "\x66\x66\x66\x64\x48\x8b\x04\x25\0\0\0\0", 12); // The next reloc should be a PLT32 reloc against __tls_get_addr. // We can skip it. this->skip_call_tls_get_addr_ = true; } // Do a relocation in which we convert a TLS Initial-Exec to a // Local-Exec. inline void Target_x86_64::Relocate::tls_ie_to_le(const Relocate_info<64, false>* relinfo, size_t relnum, Output_segment* tls_segment, const elfcpp::Rela<64, false>& rela, unsigned int, elfcpp::Elf_types<64>::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; view[-2] = 0xc7; view[-1] = 0xc0 | reg; } else if (reg == 4) { // Special handling for %rsp. if (op1 == 0x4c) view[-3] = 0x49; view[-2] = 0x81; view[-1] = 0xc0 | reg; } else { // addq if (op1 == 0x4c) view[-3] = 0x4d; view[-2] = 0x8d; view[-1] = 0x80 | reg | (reg << 3); } value -= tls_segment->memsz(); Relocate_functions<64, false>::rela32(view, value, 0); } // Relocate section data. void Target_x86_64::relocate_section( const Relocate_info<64, false>* relinfo, unsigned int sh_type, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, bool needs_special_offset_handling, unsigned char* view, elfcpp::Elf_types<64>::Elf_Addr address, section_size_type view_size, const Reloc_symbol_changes* reloc_symbol_changes) { gold_assert(sh_type == elfcpp::SHT_RELA); gold::relocate_section<64, false, Target_x86_64, elfcpp::SHT_RELA, Target_x86_64::Relocate>( relinfo, this, prelocs, reloc_count, output_section, needs_special_offset_handling, view, address, view_size, reloc_symbol_changes); } // Return the size of a relocation while scanning during a relocatable // link. unsigned int Target_x86_64::Relocatable_size_for_reloc::get_size_for_reloc( unsigned int r_type, Relobj* object) { switch (r_type) { case elfcpp::R_X86_64_NONE: case elfcpp::R_386_GNU_VTINHERIT: case elfcpp::R_386_GNU_VTENTRY: 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 0; case elfcpp::R_X86_64_64: case elfcpp::R_X86_64_PC64: case elfcpp::R_X86_64_GOTOFF64: case elfcpp::R_X86_64_GOTPC64: case elfcpp::R_X86_64_PLTOFF64: case elfcpp::R_X86_64_GOT64: case elfcpp::R_X86_64_GOTPCREL64: case elfcpp::R_X86_64_GOTPCREL: case elfcpp::R_X86_64_GOTPLT64: return 8; case elfcpp::R_X86_64_32: case elfcpp::R_X86_64_32S: case elfcpp::R_X86_64_PC32: case elfcpp::R_X86_64_PLT32: case elfcpp::R_X86_64_GOTPC32: case elfcpp::R_X86_64_GOT32: return 4; case elfcpp::R_X86_64_16: case elfcpp::R_X86_64_PC16: return 2; case elfcpp::R_X86_64_8: case elfcpp::R_X86_64_PC8: return 1; 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: // 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: object->error(_("unexpected reloc %u in object file"), r_type); return 0; case elfcpp::R_X86_64_SIZE32: case elfcpp::R_X86_64_SIZE64: default: object->error(_("unsupported reloc %u against local symbol"), r_type); return 0; } } // Scan the relocs during a relocatable link. void Target_x86_64::scan_relocatable_relocs(const General_options& options, Symbol_table* symtab, Layout* layout, Sized_relobj<64, false>* object, unsigned int data_shndx, unsigned int sh_type, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, bool needs_special_offset_handling, size_t local_symbol_count, const unsigned char* plocal_symbols, Relocatable_relocs* rr) { gold_assert(sh_type == elfcpp::SHT_RELA); typedef gold::Default_scan_relocatable_relocs<elfcpp::SHT_RELA, Relocatable_size_for_reloc> Scan_relocatable_relocs; gold::scan_relocatable_relocs<64, false, elfcpp::SHT_RELA, Scan_relocatable_relocs>( options, symtab, layout, object, data_shndx, prelocs, reloc_count, output_section, needs_special_offset_handling, local_symbol_count, plocal_symbols, rr); } // Relocate a section during a relocatable link. void Target_x86_64::relocate_for_relocatable( const Relocate_info<64, false>* relinfo, unsigned int sh_type, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, off_t offset_in_output_section, const Relocatable_relocs* rr, unsigned char* view, elfcpp::Elf_types<64>::Elf_Addr view_address, section_size_type view_size, unsigned char* reloc_view, section_size_type reloc_view_size) { gold_assert(sh_type == elfcpp::SHT_RELA); gold::relocate_for_relocatable<64, false, elfcpp::SHT_RELA>( relinfo, prelocs, reloc_count, output_section, offset_in_output_section, rr, view, view_address, view_size, reloc_view, reloc_view_size); } // Return the value to use for a dynamic which requires special // treatment. This is how we support equality comparisons of function // pointers across shared library boundaries, as described in the // processor specific ABI supplement. uint64_t Target_x86_64::do_dynsym_value(const Symbol* gsym) const { gold_assert(gsym->is_from_dynobj() && gsym->has_plt_offset()); return this->plt_section()->address() + gsym->plt_offset(); } // Return a string used to fill a code section with nops to take up // the specified length. std::string Target_x86_64::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, '\0')); } // Nop sequences of various lengths. const char nop1[1] = { 0x90 }; // nop const char nop2[2] = { 0x66, 0x90 }; // xchg %ax %ax const char nop3[3] = { 0x0f, 0x1f, 0x00 }; // nop (%rax) const char nop4[4] = { 0x0f, 0x1f, 0x40, 0x00}; // nop 0(%rax) const char nop5[5] = { 0x0f, 0x1f, 0x44, 0x00, // nop 0(%rax,%rax,1) 0x00 }; const char nop6[6] = { 0x66, 0x0f, 0x1f, 0x44, // nopw 0(%rax,%rax,1) 0x00, 0x00 }; const char nop7[7] = { 0x0f, 0x1f, 0x80, 0x00, // nopl 0L(%rax) 0x00, 0x00, 0x00 }; const char nop8[8] = { 0x0f, 0x1f, 0x84, 0x00, // nopl 0L(%rax,%rax,1) 0x00, 0x00, 0x00, 0x00 }; const char nop9[9] = { 0x66, 0x0f, 0x1f, 0x84, // nopw 0L(%rax,%rax,1) 0x00, 0x00, 0x00, 0x00, 0x00 }; const char nop10[10] = { 0x66, 0x2e, 0x0f, 0x1f, // nopw %cs:0L(%rax,%rax,1) 0x84, 0x00, 0x00, 0x00, 0x00, 0x00 }; const char nop11[11] = { 0x66, 0x66, 0x2e, 0x0f, // data16 0x1f, 0x84, 0x00, 0x00, // nopw %cs:0L(%rax,%rax,1) 0x00, 0x00, 0x00 }; const char nop12[12] = { 0x66, 0x66, 0x66, 0x2e, // data16; data16 0x0f, 0x1f, 0x84, 0x00, // nopw %cs:0L(%rax,%rax,1) 0x00, 0x00, 0x00, 0x00 }; const char nop13[13] = { 0x66, 0x66, 0x66, 0x66, // data16; data16; data16 0x2e, 0x0f, 0x1f, 0x84, // nopw %cs:0L(%rax,%rax,1) 0x00, 0x00, 0x00, 0x00, 0x00 }; const char nop14[14] = { 0x66, 0x66, 0x66, 0x66, // data16; data16; data16 0x66, 0x2e, 0x0f, 0x1f, // data16 0x84, 0x00, 0x00, 0x00, // nopw %cs:0L(%rax,%rax,1) 0x00, 0x00 }; const char nop15[15] = { 0x66, 0x66, 0x66, 0x66, // data16; data16; data16 0x66, 0x66, 0x2e, 0x0f, // data16; data16 0x1f, 0x84, 0x00, 0x00, // nopw %cs:0L(%rax,%rax,1) 0x00, 0x00, 0x00 }; 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); } // FNOFFSET in section SHNDX in OBJECT is the start of a function // compiled with -fstack-split. The function calls non-stack-split // code. We have to change the function so that it always ensures // that it has enough stack space to run some random function. void Target_x86_64::do_calls_non_split(Relobj* object, unsigned int shndx, section_offset_type fnoffset, section_size_type fnsize, unsigned char* view, section_size_type view_size, std::string* from, std::string* to) const { // The function starts with a comparison of the stack pointer and a // field in the TCB. This is followed by a jump. // cmp %fs:NN,%rsp if (this->match_view(view, view_size, fnoffset, "\x64\x48\x3b\x24\x25", 5) && fnsize > 9) { // 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, 8); } // lea NN(%rsp),%r10 else if (this->match_view(view, view_size, fnoffset, "\x4c\x8d\x94\x24", 4) && 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, 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. class Target_selector_x86_64 : public Target_selector_freebsd { public: Target_selector_x86_64() : Target_selector_freebsd(elfcpp::EM_X86_64, 64, false, "elf64-x86-64", "elf64-x86-64-freebsd") { } Target* do_instantiate_target() { return new Target_x86_64(); } }; Target_selector_x86_64 target_selector_x86_64; } // End anonymous namespace.
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