From 7223e9ca5a5ab5eecd2d14328ceade93bcb43f3d Mon Sep 17 00:00:00 2001 From: Ian Lance Taylor Date: Thu, 19 Aug 2010 22:50:16 +0000 Subject: PR 10893 * i386.cc (class Output_data_plt_i386): Update declarations. Define Global_ifunc and Local_ifunc types. Add global_ifuncs_ and local_ifuncs_ fields. (Target_i386::do_plt_section_for_global): New function. (Target_i386::do_plt_section_for_local): New function. (Output_data_plt_i386::Output_data_plt_i386): Add symtab parameter; change all callers. Initialize global_ifuncs_ and local_ifuncs_. If doing a static link define __rel_iplt_start and __rel_iplt_end. (Output_data_plt_i386::add_entry): Handle IFUNC symbols. (Output_data_plt_i386::add_local_ifunc_entry): New function. (Output_data_plt_i386::do_write): Fix GOT entries for IFUNC symbols. (Target_i386::make_plt_section): New function, broken out of make_plt_entry. Set sh_info field of .rel.plt to point to .plt. (Target_i386::make_plt_entry): Call make_plt_section. (Target_i386::make_local_ifunc_plt_entry): New function. (Target_i386::Scan::reloc_needs_iplt_for_ifunc): New function. (Target_i386::Scan::local): Handle IFUNC symbols. Add R_386_IRELATIVE to switch. (Target_i386::Scan::global): Likewise. (Target_i386::Relocate::relocate): Likewise. (Target_i386::Relocatable_size_for_reloc): Add R_386_IRELATIVE to switch. * x86_64.cc (class Output_data_plt_x86_64): Update declarations. (Target_x86_64::do_plt_section_for_global): New function. (Target_x86_64::do_plt_section_for_local): New function. (Output_data_plt_x86_64::Output_data_plt_x86_64): Add symtab parameter; change all callers. If doing a static link define __rela_iplt_start and __rela_iplt_end. (Output_data_plt_x86_64::add_entry): Handle IFUNC symbols. (Output_data_plt_x86_64::add_local_ifunc_entry): New function. (Target_x86_64::make_plt_section): Set sh_info field of .rel.plt to point to .plt. (Target_x86_64::make_local_ifunc_plt_entry): New function. (Target_x86_64::Scan::check_non_pic): Add R_X86_64_IRELATIVE to switch. (Target_x86_64::Scan::reloc_needs_iplt_for_ifunc): New function. (Target_x86_64::Scan::local): Handle IFUNC symbols. Add R_X86_64_IRELATIVE to switch. (Target_x86_64::Scan::global): Likewise. (Target_x86_64::Relocate::relocate): Likewise. (Target_x86_64::Relocatable_size_for_reloc): Add R_X86_64_IRELATIVE to switch. * target.h (class Target): Add plt_section_for_global and plt_section_for_local functions. Add do_plt_section_for_global and do_plt_section_for_local virtual functions. * symtab.h (Symbol::needs_plt_entry): Handle IFUNC symbol. Add clarifying comments. (Symbol::use_plt_offset): Handle IFUNC symbol. * object.cc (Sized_relobj::Sized_relobj): Initialize local_plt_offsets_. (Sized_relobj::local_has_plt_offset): New function. (Sized_relobj::local_plt_offset): New function. (Sized_relobj::set_local_plt_offset): New function. (Sized_relobj::do_count): Handle IFUNC symbol. * object.h (class Symbol_value): Add is_ifunc_symbol_ field. Take a bit away from input_shndx_ field. Add set_is_func_symbol and is_ifunc_symbol functions. (class Sized_relobj): Update declarations. Remove Tls_got_entry and Local_tls_got_offsets. Define Local_plt_offsets. Add local_plt_offsets_ field. (Sized_relobj::clear_local_symbols): Clear local_plt_offsets_. * output.h (class Output_section_data): Add non-const output_section function. (class Output_data_got): Update declarations. (class Output_data_got::Got_entry): Add use_plt_offset_ field. Add use_plt_offset parameter to global and local constructors. Change all callers. Change local_sym_index_ field to 31 bits. Change GSYM_CODE and CONSTANT_CODE accordingly. * output.cc (Output_data_reloc_base::do_adjust_output_section): If doing a static link don't set sh_link field. (Output_data_got::Got_entry::write): Use PLT offset if appropriate. (Output_data_got::add_global_plt): New function. (Output_data_got::add_local_plt): New function. * target-reloc.h (relocate_section): Handle IFUNC symbol. * defstd.cc (in_section): Remove entries for __rel_iplt_start, __rel_iplt_end, __rela_iplt_start, and __rela_iplt_end. * configure.ac: Set IFUNC automake conditional for glibc >= 2.11. * testsuite/Makefile.am: Add a bunch of IFUNC tests, all within IFUNC conditional. * testsuite/ifunc-sel.h: New file. * testsuite/ifuncmain1.c: New file. * testsuite/ifuncmain1vis.c: New file. * testsuite/ifuncmod1.c: New file. * testsuite/ifuncdep2.c: New file. * testsuite/ifuncmain2.c: New file. * testsuite/ifuncmain3.c: New file. * testsuite/ifuncmod3.c: New file. * testsuite/ifuncmain4.c: New file. * testsuite/ifuncmain5.c: New file. * testsuite/ifuncmod5.c: New file. * testsuite/ifuncmain6pie.c: New file. * testsuite/ifuncmod6.c: New file. * testsuite/ifuncmain7.c: New file. * configure, testsuite/Makefile.in: Rebuild. --- gold/x86_64.cc | 513 ++++++++++++++++++++++++++++++++++++++++++--------------- 1 file changed, 379 insertions(+), 134 deletions(-) (limited to 'gold/x86_64.cc') diff --git a/gold/x86_64.cc b/gold/x86_64.cc index df46f2b..b137db3 100644 --- a/gold/x86_64.cc +++ b/gold/x86_64.cc @@ -46,7 +46,115 @@ namespace using namespace gold; -class Output_data_plt_x86_64; +// 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(Symbol_table*, Layout*, Output_data_got<64, false>*, + Output_data_space*); + + // Add an entry to the PLT. + void + add_entry(Symbol* gsym); + + // Add an entry to the PLT for a local STT_GNU_IFUNC symbol. + unsigned int + add_local_ifunc_entry(Sized_relobj<64, false>* relobj, + unsigned int local_sym_index); + + // 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 .rela.plt section data. + Reloc_section* + rela_plt() + { return this->rel_; } + + // Return where the TLSDESC relocations should go. + Reloc_section* + rela_tlsdesc(Layout*); + + // Return the number of PLT entries. + unsigned int + entry_count() const + { return this->count_; } + + // Return the offset of the first non-reserved PLT entry. + static unsigned int + first_plt_entry_offset() + { return plt_entry_size; } + + // Return the size of a PLT entry. + static unsigned int + get_plt_entry_size() + { return plt_entry_size; } + + protected: + void + do_adjust_output_section(Output_section* os); + + // Write to a map file. + void + do_print_to_mapfile(Mapfile* mapfile) const + { mapfile->print_output_data(this, _("** PLT")); } + + private: + // The size of an entry in the PLT. + static const int plt_entry_size = 16; + + // The first entry in the PLT. + // 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 TLSDESC relocs, if necessary. These must follow the regular + // PLT relocs. + Reloc_section* tlsdesc_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_; +}; // The x86_64 target class. // See the ABI at @@ -188,6 +296,15 @@ class Target_x86_64 : public Target_freebsd<64, false> uint64_t do_reloc_addend(void* arg, unsigned int r_type, uint64_t addend) const; + // Return the PLT section. + Output_data* + do_plt_section_for_global(const Symbol*) const + { return this->plt_section(); } + + Output_data* + do_plt_section_for_local(const Relobj*, unsigned int) const + { return this->plt_section(); } + // Adjust -fstack-split code which calls non-stack-split code. void do_calls_non_split(Relobj* object, unsigned int shndx, @@ -291,6 +408,9 @@ class Target_x86_64 : public Target_freebsd<64, false> inline bool possible_function_pointer_reloc(unsigned int r_type); + bool + reloc_needs_plt_for_ifunc(Sized_relobj<64, false>*, unsigned int r_type); + // Whether we have issued an error about a non-PIC compilation. bool issued_non_pic_error_; }; @@ -441,6 +561,12 @@ class Target_x86_64 : public Target_freebsd<64, false> void make_plt_entry(Symbol_table*, Layout*, Symbol*); + // Create a PLT entry for a local STT_GNU_IFUNC symbol. + void + make_local_ifunc_plt_entry(Symbol_table*, Layout*, + Sized_relobj<64, false>* relobj, + unsigned int local_sym_index); + // Define the _TLS_MODULE_BASE_ symbol in the TLS segment. void define_tls_base_symbol(Symbol_table*, Layout*); @@ -641,116 +767,12 @@ Target_x86_64::rela_dyn_section(Layout* layout) 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_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 .rela.plt section data. - const Reloc_section* - rela_plt() const - { return this->rel_; } - - // Return where the TLSDESC relocations should go. - Reloc_section* - rela_tlsdesc(Layout*); - - // Return the number of PLT entries. - unsigned int - entry_count() const - { return this->count_; } - - // Return the offset of the first non-reserved PLT entry. - static unsigned int - first_plt_entry_offset() - { return plt_entry_size; } - - // Return the size of a PLT entry. - static unsigned int - get_plt_entry_size() - { return plt_entry_size; } - - protected: - void - do_adjust_output_section(Output_section* os); - - // Write to a map file. - void - do_print_to_mapfile(Mapfile* mapfile) const - { mapfile->print_output_data(this, _("** PLT")); } - - private: - // The size of an entry in the PLT. - static const int plt_entry_size = 16; - - // The first entry in the PLT. - // 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 TLSDESC relocs, if necessary. These must follow the regular - // PLT relocs. - Reloc_section* tlsdesc_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_plt_x86_64::Output_data_plt_x86_64(Symbol_table* symtab, + Layout* layout, Output_data_got<64, false>* got, Output_data_space* got_plt) : Output_section_data(8), tlsdesc_rel_(NULL), got_(got), got_plt_(got_plt), @@ -760,6 +782,24 @@ Output_data_plt_x86_64::Output_data_plt_x86_64(Layout* layout, layout->add_output_section_data(".rela.plt", elfcpp::SHT_RELA, elfcpp::SHF_ALLOC, this->rel_, ORDER_DYNAMIC_PLT_RELOCS, false); + + if (parameters->doing_static_link()) + { + // A statically linked executable will only have a .rela.plt + // section to hold R_X86_64_IRELATIVE relocs for STT_GNU_IFUNC + // symbols. The library will use these symbols to locate the + // IRELATIVE relocs at program startup time. + symtab->define_in_output_data("__rela_iplt_start", NULL, + Symbol_table::PREDEFINED, + this->rel_, 0, 0, elfcpp::STT_NOTYPE, + elfcpp::STB_GLOBAL, elfcpp::STV_HIDDEN, + 0, false, true); + symtab->define_in_output_data("__rela_iplt_end", NULL, + Symbol_table::PREDEFINED, + this->rel_, 0, 0, elfcpp::STT_NOTYPE, + elfcpp::STB_GLOBAL, elfcpp::STV_HIDDEN, + 0, true, true); + } } void @@ -789,15 +829,46 @@ Output_data_plt_x86_64::add_entry(Symbol* gsym) 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); + if (gsym->type() == elfcpp::STT_GNU_IFUNC + && gsym->can_use_relative_reloc(false)) + this->rel_->add_symbolless_global_addend(gsym, elfcpp::R_X86_64_IRELATIVE, + this->got_plt_, got_offset, 0); + else + { + gsym->set_needs_dynsym_entry(); + this->rel_->add_global(gsym, elfcpp::R_X86_64_JUMP_SLOT, this->got_plt_, + got_offset, 0); + } // Note that we don't need to save the symbol. The contents of the // PLT are independent of which symbols are used. The symbols only // appear in the relocations. } +// Add an entry to the PLT for a local STT_GNU_IFUNC symbol. Return +// the PLT offset. + +unsigned int +Output_data_plt_x86_64::add_local_ifunc_entry(Sized_relobj<64, false>* relobj, + unsigned int local_sym_index) +{ + unsigned int plt_offset = (this->count_ + 1) * plt_entry_size; + ++this->count_; + + section_offset_type got_offset = this->got_plt_->current_data_size(); + + // Every PLT entry needs a GOT entry which points back to the PLT + // entry. + this->got_plt_->set_current_data_size(got_offset + 8); + + // Every PLT entry needs a reloc. + this->rel_->add_symbolless_local_addend(relobj, local_sym_index, + elfcpp::R_X86_64_IRELATIVE, + this->got_plt_, got_offset, 0); + + return plt_offset; +} + // Return where the TLSDESC relocations should go, creating it if // necessary. These follow the JUMP_SLOT relocations. @@ -968,12 +1039,16 @@ Target_x86_64::make_plt_section(Symbol_table* symtab, Layout* layout) // Create the GOT sections first. this->got_section(symtab, layout); - this->plt_ = new Output_data_plt_x86_64(layout, this->got_, + this->plt_ = new Output_data_plt_x86_64(symtab, layout, this->got_, this->got_plt_); layout->add_output_section_data(".plt", elfcpp::SHT_PROGBITS, (elfcpp::SHF_ALLOC | elfcpp::SHF_EXECINSTR), this->plt_, ORDER_PLT, false); + + // Make the sh_info field of .rela.plt point to .plt. + Output_section* rela_plt_os = this->plt_->rela_plt()->output_section(); + rela_plt_os->set_info_section(this->plt_->output_section()); } } @@ -1000,6 +1075,22 @@ Target_x86_64::make_plt_entry(Symbol_table* symtab, Layout* layout, this->plt_->add_entry(gsym); } +// Make a PLT entry for a local STT_GNU_IFUNC symbol. + +void +Target_x86_64::make_local_ifunc_plt_entry(Symbol_table* symtab, Layout* layout, + Sized_relobj<64, false>* relobj, + unsigned int local_sym_index) +{ + if (relobj->local_has_plt_offset(local_sym_index)) + return; + if (this->plt_ == NULL) + this->make_plt_section(symtab, layout); + unsigned int plt_offset = this->plt_->add_local_ifunc_entry(relobj, + local_sym_index); + relobj->set_local_plt_offset(local_sym_index, plt_offset); +} + // Return the number of entries in the PLT. unsigned int @@ -1172,6 +1263,7 @@ Target_x86_64::Scan::check_non_pic(Relobj* object, unsigned int r_type) { // These are the relocation types supported by glibc for x86_64. case elfcpp::R_X86_64_RELATIVE: + case elfcpp::R_X86_64_IRELATIVE: case elfcpp::R_X86_64_GLOB_DAT: case elfcpp::R_X86_64_JUMP_SLOT: case elfcpp::R_X86_64_DTPMOD64: @@ -1200,6 +1292,72 @@ Target_x86_64::Scan::check_non_pic(Relobj* object, unsigned int r_type) } } +// Return whether we need to make a PLT entry for a relocation of the +// given type against a STT_GNU_IFUNC symbol. + +bool +Target_x86_64::Scan::reloc_needs_plt_for_ifunc(Sized_relobj<64, false>* object, + unsigned int r_type) +{ + switch (r_type) + { + case elfcpp::R_X86_64_NONE: + case elfcpp::R_X86_64_GNU_VTINHERIT: + case elfcpp::R_X86_64_GNU_VTENTRY: + return false; + + case elfcpp::R_X86_64_64: + case elfcpp::R_X86_64_32: + case elfcpp::R_X86_64_32S: + case elfcpp::R_X86_64_16: + case elfcpp::R_X86_64_8: + case elfcpp::R_X86_64_PC64: + case elfcpp::R_X86_64_PC32: + case elfcpp::R_X86_64_PC16: + case elfcpp::R_X86_64_PC8: + case elfcpp::R_X86_64_PLT32: + case elfcpp::R_X86_64_GOTPC32: + 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_GOT32: + case elfcpp::R_X86_64_GOTPCREL64: + case elfcpp::R_X86_64_GOTPCREL: + case elfcpp::R_X86_64_GOTPLT64: + return true; + + case elfcpp::R_X86_64_COPY: + case elfcpp::R_X86_64_GLOB_DAT: + case elfcpp::R_X86_64_JUMP_SLOT: + case elfcpp::R_X86_64_RELATIVE: + case elfcpp::R_X86_64_IRELATIVE: + case elfcpp::R_X86_64_TPOFF64: + case elfcpp::R_X86_64_DTPMOD64: + case elfcpp::R_X86_64_TLSDESC: + // We will give an error later. + return false; + + case elfcpp::R_X86_64_TLSGD: + case elfcpp::R_X86_64_GOTPC32_TLSDESC: + case elfcpp::R_X86_64_TLSDESC_CALL: + case elfcpp::R_X86_64_TLSLD: + case elfcpp::R_X86_64_DTPOFF32: + case elfcpp::R_X86_64_DTPOFF64: + case elfcpp::R_X86_64_GOTTPOFF: + case elfcpp::R_X86_64_TPOFF32: + gold_error(_("%s: unsupported TLS reloc %u for IFUNC symbol"), + object->name().c_str(), r_type); + return false; + + case elfcpp::R_X86_64_SIZE32: + case elfcpp::R_X86_64_SIZE64: + default: + // We will give an error later. + return false; + } +} + // Scan a relocation for a local symbol. inline void @@ -1213,6 +1371,14 @@ Target_x86_64::Scan::local(Symbol_table* symtab, unsigned int r_type, const elfcpp::Sym<64, false>& lsym) { + // A local STT_GNU_IFUNC symbol may require a PLT entry. + if (lsym.get_st_type() == elfcpp::STT_GNU_IFUNC + && this->reloc_needs_plt_for_ifunc(object, r_type)) + { + unsigned int r_sym = elfcpp::elf_r_sym<64>(reloc.get_r_info()); + target->make_local_ifunc_plt_entry(symtab, layout, object, r_sym); + } + switch (r_type) { case elfcpp::R_X86_64_NONE: @@ -1231,11 +1397,11 @@ Target_x86_64::Scan::local(Symbol_table* symtab, { 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()); + 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; @@ -1306,7 +1472,16 @@ Target_x86_64::Scan::local(Symbol_table* symtab, // 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)) + + // For a STT_GNU_IFUNC symbol we want the PLT offset. That + // lets function pointers compare correctly with shared + // libraries. Otherwise we would need an IRELATIVE reloc. + bool is_new; + if (lsym.get_st_type() == elfcpp::STT_GNU_IFUNC) + is_new = got->add_local_plt(object, r_sym, GOT_TYPE_STANDARD); + else + is_new = got->add_local(object, r_sym, GOT_TYPE_STANDARD); + if (is_new) { // If we are generating a shared object, we need to add a // dynamic relocation for this symbol's GOT entry. @@ -1315,9 +1490,13 @@ Target_x86_64::Scan::local(Symbol_table* symtab, 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); + { + unsigned int got_offset = + object->local_got_offset(r_sym, GOT_TYPE_STANDARD); + rela_dyn->add_local_relative(object, r_sym, + elfcpp::R_X86_64_RELATIVE, + got, got_offset, 0); + } else { this->check_non_pic(object, r_type); @@ -1338,6 +1517,7 @@ Target_x86_64::Scan::local(Symbol_table* symtab, case elfcpp::R_X86_64_GLOB_DAT: case elfcpp::R_X86_64_JUMP_SLOT: case elfcpp::R_X86_64_RELATIVE: + case elfcpp::R_X86_64_IRELATIVE: // These are outstanding tls relocs, which are unexpected when linking case elfcpp::R_X86_64_TPOFF64: case elfcpp::R_X86_64_DTPMOD64: @@ -1571,6 +1751,11 @@ Target_x86_64::Scan::global(Symbol_table* symtab, unsigned int r_type, Symbol* gsym) { + // A STT_GNU_IFUNC symbol may require a PLT entry. + if (gsym->type() == elfcpp::STT_GNU_IFUNC + && this->reloc_needs_plt_for_ifunc(object, r_type)) + target->make_plt_entry(symtab, layout, gsym); + switch (r_type) { case elfcpp::R_X86_64_NONE: @@ -1603,14 +1788,34 @@ Target_x86_64::Scan::global(Symbol_table* symtab, target->copy_reloc(symtab, layout, object, data_shndx, output_section, gsym, reloc); } + else if (r_type == elfcpp::R_X86_64_64 + && gsym->type() == elfcpp::STT_GNU_IFUNC + && gsym->can_use_relative_reloc(false) + && !gsym->is_from_dynobj() + && !gsym->is_undefined() + && !gsym->is_preemptible()) + { + // Use an IRELATIVE reloc for a locally defined + // STT_GNU_IFUNC symbol. This makes a function + // address in a PIE executable match the address in a + // shared library that it links against. + Reloc_section* rela_dyn = target->rela_dyn_section(layout); + unsigned int r_type = elfcpp::R_X86_64_IRELATIVE; + rela_dyn->add_symbolless_global_addend(gsym, r_type, + output_section, object, + data_shndx, + reloc.get_r_offset(), + reloc.get_r_addend()); + } else if (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()); + 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 { @@ -1664,23 +1869,49 @@ Target_x86_64::Scan::global(Symbol_table* symtab, // 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); + { + // For a STT_GNU_IFUNC symbol we want the PLT address. + if (gsym->type() == elfcpp::STT_GNU_IFUNC) + got->add_global_plt(gsym, GOT_TYPE_STANDARD); + else + got->add_global(gsym, GOT_TYPE_STANDARD); + } else { // If this symbol is not fully resolved, we need to add a // dynamic relocation for it. Reloc_section* rela_dyn = target->rela_dyn_section(layout); - if (gsym->is_from_dynobj() - || gsym->is_undefined() - || gsym->is_preemptible()) + if (gsym->is_from_dynobj() + || gsym->is_undefined() + || gsym->is_preemptible() + || (gsym->type() == elfcpp::STT_GNU_IFUNC + && parameters->options().output_is_position_independent())) got->add_global_with_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 a STT_GNU_IFUNC symbol we want to write the PLT + // offset into the GOT, so that function pointer + // comparisons work correctly. + bool is_new; + if (gsym->type() != elfcpp::STT_GNU_IFUNC) + is_new = got->add_global(gsym, GOT_TYPE_STANDARD); + else + { + is_new = got->add_global_plt(gsym, GOT_TYPE_STANDARD); + // Tell the dynamic linker to use the PLT address + // when resolving relocations. + if (gsym->is_from_dynobj() + && !parameters->options().shared()) + gsym->set_needs_dynsym_value(); + } + if (is_new) + { + unsigned int got_off = gsym->got_offset(GOT_TYPE_STANDARD); + rela_dyn->add_global_relative(gsym, + elfcpp::R_X86_64_RELATIVE, + got, got_off, 0); + } } } // For GOTPLT64, we also need a PLT entry (but only if the @@ -1723,6 +1954,7 @@ Target_x86_64::Scan::global(Symbol_table* symtab, case elfcpp::R_X86_64_GLOB_DAT: case elfcpp::R_X86_64_JUMP_SLOT: case elfcpp::R_X86_64_RELATIVE: + case elfcpp::R_X86_64_IRELATIVE: // These are outstanding tls relocs, which are unexpected when linking case elfcpp::R_X86_64_TPOFF64: case elfcpp::R_X86_64_DTPMOD64: @@ -2007,7 +2239,9 @@ Target_x86_64::Relocate::relocate(const Relocate_info<64, false>* relinfo, } } - // Pick the value to use for symbols defined in shared objects. + const Sized_relobj<64, false>* object = relinfo->object; + + // Pick the value to use for symbols defined in the PLT. Symbol_value<64> symval; if (gsym != NULL && gsym->use_plt_offset(r_type == elfcpp::R_X86_64_PC64 @@ -2019,8 +2253,17 @@ Target_x86_64::Relocate::relocate(const Relocate_info<64, false>* relinfo, + gsym->plt_offset()); psymval = &symval; } + else if (gsym == NULL && psymval->is_ifunc_symbol()) + { + unsigned int r_sym = elfcpp::elf_r_sym<64>(rela.get_r_info()); + if (object->local_has_plt_offset(r_sym)) + { + symval.set_output_value(target->plt_section()->address() + + object->local_plt_offset(r_sym)); + psymval = &symval; + } + } - const Sized_relobj<64, false>* object = relinfo->object; const elfcpp::Elf_Xword addend = rela.get_r_addend(); // Get the GOT offset if needed. @@ -2196,6 +2439,7 @@ Target_x86_64::Relocate::relocate(const Relocate_info<64, false>* relinfo, case elfcpp::R_X86_64_GLOB_DAT: case elfcpp::R_X86_64_JUMP_SLOT: case elfcpp::R_X86_64_RELATIVE: + case elfcpp::R_X86_64_IRELATIVE: // These are outstanding tls relocs, which are unexpected when linking case elfcpp::R_X86_64_TPOFF64: case elfcpp::R_X86_64_DTPMOD64: @@ -2789,6 +3033,7 @@ Target_x86_64::Relocatable_size_for_reloc::get_size_for_reloc( case elfcpp::R_X86_64_GLOB_DAT: case elfcpp::R_X86_64_JUMP_SLOT: case elfcpp::R_X86_64_RELATIVE: + case elfcpp::R_X86_64_IRELATIVE: // These are outstanding tls relocs, which are unexpected when linking case elfcpp::R_X86_64_TPOFF64: case elfcpp::R_X86_64_DTPMOD64: -- cgit v1.1