// x86_64.cc -- x86_64 target support for gold. // Copyright 2006, 2007, Free Software Foundation, Inc. // Written by Ian Lance Taylor . // This file is part of gold. // This program is free software; you can redistribute it and/or // modify it under the terms of the GNU Library General Public License // as published by the Free Software Foundation; either version 2, or // (at your option) any later version. // In addition to the permissions in the GNU Library General Public // License, the Free Software Foundation gives you unlimited // permission to link the compiled version of this file into // combinations with other programs, and to distribute those // combinations without any restriction coming from the use of this // file. (The Library Public License restrictions do apply in other // respects; for example, they cover modification of the file, and /// distribution when not linked into a combined executable.) // 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 // Library General Public License for more details. // You should have received a copy of the GNU Library General Public // License along with this program; if not, write to the Free Software // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA // 02110-1301, USA. #include "gold.h" #include #include "elfcpp.h" #include "parameters.h" #include "reloc.h" #include "x86_64.h" #include "object.h" #include "symtab.h" #include "layout.h" #include "output.h" #include "target.h" #include "target-reloc.h" #include "target-select.h" #include "tls.h" namespace { using namespace gold; class Output_data_plt_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 Sized_target<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 Reloc_section; Target_x86_64() : Sized_target<64, false>(&x86_64_info), got_(NULL), plt_(NULL), got_plt_(NULL), rela_dyn_(NULL), copy_relocs_(NULL), dynbss_(NULL) { } // 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, size_t local_symbol_count, const unsigned char* plocal_symbols, Symbol** global_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, unsigned char* view, elfcpp::Elf_types<64>::Elf_Addr view_address, off_t view_size); // Return a string used to fill a code section with nops. std::string do_code_fill(off_t length); private: // The class which scans relocations. struct Scan { 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, 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, const elfcpp::Rela<64, false>& reloc, unsigned int r_type, Symbol* gsym); 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*); }; // 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<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, off_t); private: // Do a TLS relocation. inline void relocate_tls(const Relocate_info<64, false>*, 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, off_t); // 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, off_t 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, off_t 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, off_t 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_; }; // 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*); // Create a PLT entry for a global symbol. void make_plt_entry(Symbol_table*, Layout*, Symbol*); // 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*); // Copy a relocation against a global symbol. void copy_reloc(const General_options*, Symbol_table*, Layout*, Sized_relobj<64, false>*, unsigned int, Symbol*, const elfcpp::Rela<64, false>&); // Information about this specific target which we pass to the // general Target structure. static const Target::Target_info x86_64_info; // 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<64, false>* copy_relocs_; // Space for variables copied with a COPY reloc. Output_data_space* dynbss_; }; 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 "/lib/ld64.so.1", // program interpreter 0x400000, // default_text_segment_address 0x1000, // abi_pagesize 0x1000 // common_pagesize }; // 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>(); layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS, elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE, this->got_); // The old GNU linker creates a .got.plt section. We just // create another set of data in the .got section. Note that we // always create a PLT if we create a GOT, although the PLT // might be empty. this->got_plt_ = new Output_data_space(8); layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS, elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE, this->got_plt_); // The first three entries are reserved. this->got_plt_->set_space_size(3 * 8); // Define _GLOBAL_OFFSET_TABLE_ at the start of the PLT. symtab->define_in_output_data(this, "_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(); layout->add_output_section_data(".rela.dyn", elfcpp::SHT_RELA, elfcpp::SHF_ALLOC, this->rela_dyn_); } 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 Reloc_section; Output_data_plt_x86_64(Layout*, Output_data_space*); // Add an entry to the PLT. void add_entry(Symbol* gsym); // Return the .rel.plt section data. const Reloc_section* rel_plt() const { return this->rel_; } protected: void do_adjust_output_section(Output_section* os); private: // The size of an entry in the PLT. static const int plt_entry_size = 16; // The first entry in the PLT. // 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]; // Set the final size. void do_set_address(uint64_t, off_t) { this->set_data_size((this->count_ + 1) * plt_entry_size); } // Write out the PLT data. void do_write(Output_file*); // The reloc section. Reloc_section* rel_; // The .got.plt section. Output_data_space* got_plt_; // The number of PLT entries. unsigned int count_; }; // Create the PLT section. The ordinary .got section is an argument, // since we need to refer to the start. We also create our own .got // section just for PLT entries. Output_data_plt_x86_64::Output_data_plt_x86_64(Layout* layout, Output_data_space* got_plt) : Output_section_data(8), got_plt_(got_plt), count_(0) { this->rel_ = new Reloc_section(); layout->add_output_section_data(".rela.plt", elfcpp::SHT_RELA, elfcpp::SHF_ALLOC, this->rel_); } void Output_data_plt_x86_64::do_adjust_output_section(Output_section* os) { // UnixWare sets the entsize of .plt to 4, and so does the old GNU // linker, and so do we. os->set_entsize(4); } // Add an entry to the PLT. void Output_data_plt_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_; off_t got_offset = this->got_plt_->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_space_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. } // 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 + 4 0xff, 0x25, // jmp indirect 0, 0, 0, 0, // replaced with address of .got + 8 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 }; // 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 off_t oview_size = 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 off_t got_size = this->got_plt_->data_size(); unsigned char* const got_view = of->get_output_view(got_file_offset, got_size); unsigned char* pov = oview; elfcpp::Elf_types<32>::Elf_Addr plt_address = this->address(); elfcpp::Elf_types<32>::Elf_Addr got_address = this->got_plt_->address(); memcpy(pov, first_plt_entry, plt_entry_size); if (!parameters->output_is_shared()) { // 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); if (parameters->output_is_shared()) // FIXME(csilvers): what's the right thing to write here? elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_offset); else 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); } gold_assert(pov - oview == oview_size); gold_assert(got_pov - got_view == got_size); of->write_output_view(offset, oview_size, oview); of->write_output_view(got_file_offset, got_size, got_view); } // Create a PLT entry for a global symbol. void Target_x86_64::make_plt_entry(Symbol_table* symtab, Layout* layout, Symbol* gsym) { if (gsym->has_plt_offset()) return; if (this->plt_ == NULL) { // Create the GOT sections first. this->got_section(symtab, layout); this->plt_ = new Output_data_plt_x86_64(layout, this->got_plt_); layout->add_output_section_data(".plt", elfcpp::SHT_PROGBITS, (elfcpp::SHF_ALLOC | elfcpp::SHF_EXECINSTR), this->plt_); } this->plt_->add_entry(gsym); } // Handle a relocation against a non-function symbol defined in a // dynamic object. The traditional way to handle this is to generate // a COPY relocation to copy the variable at runtime from the shared // object into the executable's data segment. However, this is // undesirable in general, as if the size of the object changes in the // dynamic object, the executable will no longer work correctly. If // this relocation is in a writable section, then we can create a // dynamic reloc and the dynamic linker will resolve it to the correct // address at runtime. However, we do not want do that if the // relocation is in a read-only section, as it would prevent the // readonly segment from being shared. And if we have to eventually // generate a COPY reloc, then any dynamic relocations will be // useless. So this means that if this is a writable section, we need // to save the relocation until we see whether we have to create a // COPY relocation for this symbol for any other relocation. void Target_x86_64::copy_reloc(const General_options* options, Symbol_table* symtab, Layout* layout, Sized_relobj<64, false>* object, unsigned int data_shndx, Symbol* gsym, const elfcpp::Rela<64, false>& rela) { Sized_symbol<64>* ssym; ssym = symtab->get_sized_symbol SELECT_SIZE_NAME(64) (gsym SELECT_SIZE(64)); if (!Copy_relocs<64, false>::need_copy_reloc(options, object, data_shndx, ssym)) { // So far we do not need a COPY reloc. Save this relocation. // If it turns out that we never need a COPY reloc for this // symbol, then we will emit the relocation. if (this->copy_relocs_ == NULL) this->copy_relocs_ = new Copy_relocs<64, false>(); this->copy_relocs_->save(ssym, object, data_shndx, rela); } else { // Allocate space for this symbol in the .bss section. elfcpp::Elf_types<64>::Elf_WXword symsize = ssym->symsize(); // There is no defined way to determine the required alignment // of the symbol. We pick the alignment based on the size. We // set an arbitrary maximum of 256. unsigned int align; for (align = 1; align < 512; align <<= 1) if ((symsize & align) != 0) break; if (this->dynbss_ == NULL) { this->dynbss_ = new Output_data_space(align); layout->add_output_section_data(".bss", elfcpp::SHT_NOBITS, (elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE), this->dynbss_); } Output_data_space* dynbss = this->dynbss_; if (align > dynbss->addralign()) dynbss->set_space_alignment(align); off_t dynbss_size = dynbss->data_size(); dynbss_size = align_address(dynbss_size, align); off_t offset = dynbss_size; dynbss->set_space_size(dynbss_size + symsize); symtab->define_with_copy_reloc(this, ssym, dynbss, offset); // Add the COPY reloc. Reloc_section* rela_dyn = this->rela_dyn_section(layout); rela_dyn->add_global(ssym, elfcpp::R_X86_64_COPY, dynbss, offset, 0); } } // 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->output_is_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); } // 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, const elfcpp::Rela<64, false>& reloc, unsigned int r_type, const elfcpp::Sym<64, false>&) { 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: // FIXME: If we are generating a shared object we need to copy // this relocation into the object. gold_assert(!parameters->output_is_shared()); 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)) { // If we are generating a shared object, we need to add a // dynamic RELATIVE relocation for this symbol. if (parameters->output_is_shared()) { Reloc_section* rela_dyn = target->rela_dyn_section(layout); rela_dyn->add_local(object, 0, elfcpp::R_X86_64_RELATIVE, data_shndx, reloc.get_r_offset(), 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->output_is_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 case elfcpp::R_X86_64_GOTPC32_TLSDESC: case elfcpp::R_X86_64_TLSDESC_CALL: // FIXME: If not relaxing to LE, we need to generate // DTPMOD64 and DTPOFF64 relocs. if (optimized_type != tls::TLSOPT_TO_LE) unsupported_reloc_local(object, r_type); break; case elfcpp::R_X86_64_TLSLD: // Local-dynamic case elfcpp::R_X86_64_DTPOFF32: case elfcpp::R_X86_64_DTPOFF64: // FIXME: If not relaxing to LE, we need to generate a // DTPMOD64 reloc. if (optimized_type != tls::TLSOPT_TO_LE) unsupported_reloc_local(object, r_type); break; case elfcpp::R_X86_64_GOTTPOFF: // Initial-exec // FIXME: If not relaxing to LE, we need to generate a // TPOFF64 reloc. if (optimized_type != tls::TLSOPT_TO_LE) unsupported_reloc_local(object, r_type); break; case elfcpp::R_X86_64_TPOFF32: // Local-exec // FIXME: If generating a shared object, we need to copy // this relocation into the object. gold_assert(!output_is_shared); 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->name()); } // Scan a relocation for a global symbol. inline void Target_x86_64::Scan::global(const General_options& options, Symbol_table* symtab, Layout* layout, Target_x86_64* target, Sized_relobj<64, false>* object, unsigned int data_shndx, 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_PC64: case elfcpp::R_X86_64_32: case elfcpp::R_X86_64_32S: case elfcpp::R_X86_64_PC32: case elfcpp::R_X86_64_16: case elfcpp::R_X86_64_PC16: case elfcpp::R_X86_64_8: case elfcpp::R_X86_64_PC8: // FIXME: If we are generating a shared object we may need to // copy this relocation into the object. If this symbol is // defined in a shared object, we may need to copy this // relocation in order to avoid a COPY relocation. gold_assert(!parameters->output_is_shared()); if (gsym->is_from_dynobj()) { // This symbol is defined in a dynamic object. If it is a // function, we make a PLT entry. Otherwise we need to // either generate a COPY reloc or copy this reloc. if (gsym->type() == elfcpp::STT_FUNC) { target->make_plt_entry(symtab, layout, gsym); // If this is not a PC relative reference, then we may // be taking the address of the function. In that case // we need to set the entry in the dynamic symbol table // to the address of the PLT entry. if (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) gsym->set_needs_dynsym_value(); } else target->copy_reloc(&options, symtab, layout, object, data_shndx, gsym, reloc); } 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 (got->add_global(gsym)) { // If this symbol is not fully resolved, we need to add a // dynamic relocation for it. if (!gsym->final_value_is_known()) { Reloc_section* rela_dyn = target->rela_dyn_section(layout); rela_dyn->add_global(gsym, elfcpp::R_X86_64_GLOB_DAT, got, gsym->got_offset(), 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; 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 case elfcpp::R_X86_64_GOTPC32_TLSDESC: case elfcpp::R_X86_64_TLSDESC_CALL: // FIXME: If not relaxing to LE, we need to generate // DTPMOD64 and DTPOFF64, or TLSDESC, relocs. if (optimized_type != tls::TLSOPT_TO_LE) unsupported_reloc_global(object, r_type, gsym); break; case elfcpp::R_X86_64_TLSLD: // Local-dynamic case elfcpp::R_X86_64_DTPOFF32: case elfcpp::R_X86_64_DTPOFF64: // FIXME: If not relaxing to LE, we need to generate a // DTPMOD64 reloc. if (optimized_type != tls::TLSOPT_TO_LE) unsupported_reloc_global(object, r_type, gsym); break; case elfcpp::R_X86_64_GOTTPOFF: // Initial-exec // FIXME: If not relaxing to LE, we need to generate a // TPOFF64 reloc. if (optimized_type != tls::TLSOPT_TO_LE) unsupported_reloc_global(object, r_type, gsym); break; case elfcpp::R_X86_64_TPOFF32: // Local-exec // FIXME: If generating a shared object, we need to copy // this relocation into the object. gold_assert(is_final); 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->name()); break; } } // 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, size_t local_symbol_count, const unsigned char* plocal_symbols, Symbol** global_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, local_symbol_count, plocal_symbols, global_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) odyn->add_section_address(elfcpp::DT_PLTGOT, this->got_plt_); if (this->plt_ != NULL) { const Output_data* od = this->plt_->rel_plt(); odyn->add_section_size(elfcpp::DT_PLTRELSZ, od); odyn->add_section_address(elfcpp::DT_JMPREL, od); odyn->add_constant(elfcpp::DT_PLTREL, elfcpp::DT_RELA); } if (this->rela_dyn_ != 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->output_is_shared()) { // The value of the DT_DEBUG tag is filled in by the dynamic // linker at run time, and used by the debugger. odyn->add_constant(elfcpp::DT_DEBUG, 0); } } // Emit any relocs we saved in an attempt to avoid generating COPY // relocs. if (this->copy_relocs_ == NULL) return; if (this->copy_relocs_->any_to_emit()) { Reloc_section* rela_dyn = this->rela_dyn_section(layout); this->copy_relocs_->emit(rela_dyn); } delete this->copy_relocs_; this->copy_relocs_ = NULL; } // Perform a relocation. inline bool Target_x86_64::Relocate::relocate(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, off_t view_size) { if (this->skip_call_tls_get_addr_) { if (r_type != elfcpp::R_X86_64_PLT32 || 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->is_from_dynobj() && gsym->has_plt_offset()) { 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. 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_offset = gsym->got_offset(); } else { unsigned int r_sym = elfcpp::elf_r_sym<64>(rela.get_r_info()); got_offset = object->local_got_offset(r_sym); } 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(static_cast(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(static_cast(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()); // 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_section(NULL, NULL)->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_section(NULL, NULL)->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_section(NULL, NULL)->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_section(NULL, NULL)->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_section(NULL, NULL)->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, 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, 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, off_t view_size) { Output_segment* tls_segment = relinfo->layout->tls_segment(); if (tls_segment == NULL) { gold_error_at_location(relinfo, relnum, rela.get_r_offset(), _("TLS reloc but no TLS segment")); return; } elfcpp::Elf_types<64>::Elf_Addr value = psymval->value(relinfo->object, 0); const bool is_final = (gsym == NULL ? !parameters->output_is_shared() : 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 case elfcpp::R_X86_64_GOTPC32_TLSDESC: // Global-dynamic (from ~oliva url) case elfcpp::R_X86_64_TLSDESC_CALL: if (optimized_type == tls::TLSOPT_TO_LE) { this->tls_gd_to_le(relinfo, relnum, tls_segment, rela, r_type, value, view, view_size); 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 (optimized_type == tls::TLSOPT_TO_LE) { this->tls_ld_to_le(relinfo, relnum, tls_segment, rela, r_type, value, view, view_size); 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) value = value - (tls_segment->vaddr() + tls_segment->memsz()); else value = value - tls_segment->vaddr(); Relocate_functions<64, false>::rel32(view, value); break; case elfcpp::R_X86_64_DTPOFF64: if (optimized_type == tls::TLSOPT_TO_LE) value = value - (tls_segment->vaddr() + tls_segment->memsz()); else value = value - tls_segment->vaddr(); Relocate_functions<64, false>::rel64(view, value); break; case elfcpp::R_X86_64_GOTTPOFF: // Initial-exec if (optimized_type == tls::TLSOPT_TO_LE) { Target_x86_64::Relocate::tls_ie_to_le(relinfo, relnum, tls_segment, rela, r_type, value, view, view_size); 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 = value - (tls_segment->vaddr() + tls_segment->memsz()); Relocate_functions<64, false>::rel32(view, value); break; } } // 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, off_t 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 = value - (tls_segment->vaddr() + 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; } 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, off_t 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, off_t 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 = value - (tls_segment->vaddr() + 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, unsigned char* view, elfcpp::Elf_types<64>::Elf_Addr address, off_t view_size) { 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, view, address, view_size); } // Return the value to use for a dynamic which requires special // treatment. This is how we support equality comparisons of function // pointers across shared library boundaries, as described in the // processor specific ABI supplement. uint64_t Target_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(off_t length) { if (length >= 16) { // Build a jmpq instruction to skip over the bytes. unsigned char jmp[5]; jmp[0] = 0xe9; elfcpp::Swap_unaligned<64, false>::writeval(jmp + 1, length - 5); return (std::string(reinterpret_cast(&jmp[0]), 5) + std::string(length - 5, '\0')); } // Nop sequences of various lengths. const char nop1[1] = { 0x90 }; // nop const char nop2[2] = { 0x66, 0x90 }; // xchg %ax %ax const char nop3[3] = { 0x8d, 0x76, 0x00 }; // leal 0(%esi),%esi const char nop4[4] = { 0x8d, 0x74, 0x26, 0x00}; // leal 0(%esi,1),%esi const char nop5[5] = { 0x90, 0x8d, 0x74, 0x26, // nop 0x00 }; // leal 0(%esi,1),%esi const char nop6[6] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi 0x00, 0x00 }; const char nop7[7] = { 0x8d, 0xb4, 0x26, 0x00, // leal 0L(%esi,1),%esi 0x00, 0x00, 0x00 }; const char nop8[8] = { 0x90, 0x8d, 0xb4, 0x26, // nop 0x00, 0x00, 0x00, 0x00 }; // leal 0L(%esi,1),%esi const char nop9[9] = { 0x89, 0xf6, 0x8d, 0xbc, // movl %esi,%esi 0x27, 0x00, 0x00, 0x00, // leal 0L(%edi,1),%edi 0x00 }; const char nop10[10] = { 0x8d, 0x76, 0x00, 0x8d, // leal 0(%esi),%esi 0xbc, 0x27, 0x00, 0x00, // leal 0L(%edi,1),%edi 0x00, 0x00 }; const char nop11[11] = { 0x8d, 0x74, 0x26, 0x00, // leal 0(%esi,1),%esi 0x8d, 0xbc, 0x27, 0x00, // leal 0L(%edi,1),%edi 0x00, 0x00, 0x00 }; const char nop12[12] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi 0x00, 0x00, 0x8d, 0xbf, // leal 0L(%edi),%edi 0x00, 0x00, 0x00, 0x00 }; const char nop13[13] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi 0x00, 0x00, 0x8d, 0xbc, // leal 0L(%edi,1),%edi 0x27, 0x00, 0x00, 0x00, 0x00 }; const char nop14[14] = { 0x8d, 0xb4, 0x26, 0x00, // leal 0L(%esi,1),%esi 0x00, 0x00, 0x00, 0x8d, // leal 0L(%edi,1),%edi 0xbc, 0x27, 0x00, 0x00, 0x00, 0x00 }; const char nop15[15] = { 0xeb, 0x0d, 0x90, 0x90, // jmp .+15 0x90, 0x90, 0x90, 0x90, // nop,nop,nop,... 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90 }; const char* nops[16] = { NULL, nop1, nop2, nop3, nop4, nop5, nop6, nop7, nop8, nop9, nop10, nop11, nop12, nop13, nop14, nop15 }; return std::string(nops[length], length); } // The selector for x86_64 object files. class Target_selector_x86_64 : public Target_selector { public: Target_selector_x86_64() : Target_selector(elfcpp::EM_X86_64, 64, false) { } Target* recognize(int machine, int osabi, int abiversion); private: Target_x86_64* target_; }; // Recognize an x86_64 object file when we already know that the machine // number is EM_X86_64. Target* Target_selector_x86_64::recognize(int, int, int) { if (this->target_ == NULL) this->target_ = new Target_x86_64(); return this->target_; } Target_selector_x86_64 target_selector_x86_64; } // End anonymous namespace.