diff options
Diffstat (limited to 'gold/x86_64.cc')
| -rw-r--r-- | gold/x86_64.cc | 208 |
1 files changed, 180 insertions, 28 deletions
diff --git a/gold/x86_64.cc b/gold/x86_64.cc index e4a7043..9b9a3b1 100644 --- a/gold/x86_64.cc +++ b/gold/x86_64.cc @@ -53,8 +53,31 @@ 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(Symbol_table*, Layout*, Output_data_got<64, false>*, - Output_data_space*); + 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), + count_(0), tlsdesc_got_offset_(-1U), free_list_() + { this->init(symtab, layout); } + + Output_data_plt_x86_64(Symbol_table* symtab, Layout* layout, + Output_data_got<64, false>* got, + Output_data_space* got_plt, + unsigned int plt_count) + : Output_section_data((plt_count + 1) * plt_entry_size, 8, false), + tlsdesc_rel_(NULL), got_(got), got_plt_(got_plt), + count_(plt_count), tlsdesc_got_offset_(-1U), free_list_() + { + this->init(symtab, layout); + + // Initialize the free list and reserve the first entry. + this->free_list_.init((plt_count + 1) * plt_entry_size, false); + this->free_list_.remove(0, plt_entry_size); + } + + // Initialize the PLT section. + void + init(Symbol_table* symtab, Layout* layout); // Add an entry to the PLT. void @@ -65,6 +88,10 @@ class Output_data_plt_x86_64 : public Output_section_data add_local_ifunc_entry(Sized_relobj<64, false>* relobj, unsigned int local_sym_index); + // Add the relocation for a PLT entry. + void + add_relocation(Symbol* gsym, unsigned int got_offset); + // Add the reserved TLSDESC_PLT entry to the PLT. void reserve_tlsdesc_entry(unsigned int got_offset) @@ -109,6 +136,14 @@ class Output_data_plt_x86_64 : public Output_section_data get_plt_entry_size() { return plt_entry_size; } + // Reserve a slot in the PLT for an existing symbol in an incremental update. + void + reserve_slot(unsigned int plt_index) + { + this->free_list_.remove((plt_index + 1) * plt_entry_size, + (plt_index + 2) * plt_entry_size); + } + protected: void do_adjust_output_section(Output_section* os); @@ -154,6 +189,9 @@ class Output_data_plt_x86_64 : public Output_section_data unsigned int count_; // Offset of the reserved TLSDESC_GOT entry when needed. unsigned int tlsdesc_got_offset_; + // List of available regions within the section, for incremental + // update links. + Free_list free_list_; }; // The x86_64 target class. @@ -345,6 +383,18 @@ class Target_x86_64 : public Target_freebsd<64, false> unsigned int plt_entry_size() const; + // Create the GOT section for an incremental update. + Output_data_got<64, false>* + init_got_plt_for_update(Symbol_table* symtab, + Layout* layout, + unsigned int got_count, + unsigned int plt_count); + + // Register an existing PLT entry for a global symbol. + // A target needs to implement this to support incremental linking. + void + register_global_plt_entry(unsigned int plt_index, Symbol* gsym); + // Apply an incremental relocation. void apply_relocation(const Relocate_info<64, false>* relinfo, @@ -779,16 +829,10 @@ Target_x86_64::rela_dyn_section(Layout* layout) return this->rela_dyn_; } -// Create the PLT section. The ordinary .got section is an argument, -// since we need to refer to the start. We also create our own .got -// section just for PLT entries. +// Initialize the PLT section. -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), - count_(0), tlsdesc_got_offset_(-1U) +void +Output_data_plt_x86_64::init(Symbol_table* symtab, Layout* layout) { this->rel_ = new Reloc_section(false); layout->add_output_section_data(".rela.plt", elfcpp::SHT_RELA, @@ -827,31 +871,47 @@ 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); + unsigned int plt_index; + off_t plt_offset; + section_offset_type got_offset; - ++this->count_; + if (!this->is_data_size_valid()) + { + // Note that when setting the PLT offset we skip the initial + // reserved PLT entry. + plt_index = this->count_ + 1; + plt_offset = plt_index * plt_entry_size; - section_offset_type got_offset = this->got_plt_->current_data_size(); + ++this->count_; - // 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); + got_offset = (plt_index - 1 + 3) * 8; + gold_assert(got_offset == this->got_plt_->current_data_size()); - // Every PLT entry needs a reloc. - if (gsym->type() == elfcpp::STT_GNU_IFUNC - && gsym->can_use_relative_reloc(false)) - this->rel_->add_symbolless_global_addend(gsym, elfcpp::R_X86_64_IRELATIVE, - this->got_plt_, got_offset, 0); + // 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); + } else { - gsym->set_needs_dynsym_entry(); - this->rel_->add_global(gsym, elfcpp::R_X86_64_JUMP_SLOT, this->got_plt_, - got_offset, 0); + // For incremental updates, find an available slot. + plt_offset = this->free_list_.allocate(plt_entry_size, plt_entry_size, 0); + if (plt_offset == -1) + gold_fatal(_("out of patch space (PLT);" + " relink with --incremental-full")); + + // The GOT and PLT entries have a 1-1 correspondance, so the GOT offset + // can be calculated from the PLT index, adjusting for the three + // reserved entries at the beginning of the GOT. + plt_index = plt_offset / plt_entry_size - 1; + got_offset = (plt_index - 1 + 3) * 8; } + gsym->set_plt_offset(plt_offset); + + // Every PLT entry needs a reloc. + this->add_relocation(gsym, got_offset); + // Note that we don't need to save the symbol. The contents of the // PLT are independent of which symbols are used. The symbols only // appear in the relocations. @@ -881,6 +941,23 @@ Output_data_plt_x86_64::add_local_ifunc_entry(Sized_relobj<64, false>* relobj, return plt_offset; } +// Add the relocation for a PLT entry. + +void +Output_data_plt_x86_64::add_relocation(Symbol* gsym, unsigned int got_offset) +{ + 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); + } +} + // Return where the TLSDESC relocations should go, creating it if // necessary. These follow the JUMP_SLOT relocations. @@ -1129,6 +1206,81 @@ Target_x86_64::plt_entry_size() const return Output_data_plt_x86_64::get_plt_entry_size(); } +// Create the GOT and PLT sections for an incremental update. + +Output_data_got<64, false>* +Target_x86_64::init_got_plt_for_update(Symbol_table* symtab, + Layout* layout, + unsigned int got_count, + unsigned int plt_count) +{ + gold_assert(this->got_ == NULL); + + this->got_ = new Output_data_got<64, false>(got_count * 8); + layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS, + (elfcpp::SHF_ALLOC + | elfcpp::SHF_WRITE), + this->got_, ORDER_RELRO_LAST, + true); + + // Add the three reserved entries. + this->got_plt_ = new Output_data_space((plt_count + 3) * 8, 8, "** GOT PLT"); + layout->add_output_section_data(".got.plt", elfcpp::SHT_PROGBITS, + (elfcpp::SHF_ALLOC + | elfcpp::SHF_WRITE), + this->got_plt_, ORDER_NON_RELRO_FIRST, + false); + + // Define _GLOBAL_OFFSET_TABLE_ at the start of the PLT. + this->global_offset_table_ = + symtab->define_in_output_data("_GLOBAL_OFFSET_TABLE_", NULL, + Symbol_table::PREDEFINED, + this->got_plt_, + 0, 0, elfcpp::STT_OBJECT, + elfcpp::STB_LOCAL, + elfcpp::STV_HIDDEN, 0, + false, false); + + // If there are any TLSDESC relocations, they get GOT entries in + // .got.plt after the jump slot entries. + // FIXME: Get the count for TLSDESC entries. + this->got_tlsdesc_ = new Output_data_got<64, false>(0); + layout->add_output_section_data(".got.plt", elfcpp::SHT_PROGBITS, + elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE, + this->got_tlsdesc_, + ORDER_NON_RELRO_FIRST, false); + + // Create the PLT section. + this->plt_ = new Output_data_plt_x86_64(symtab, layout, this->got_, + this->got_plt_, plt_count); + 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()); + + return this->got_; +} + +// Register an existing PLT entry for a global symbol. + +void +Target_x86_64::register_global_plt_entry(unsigned int plt_index, + Symbol* gsym) +{ + gold_assert(this->plt_ != NULL); + gold_assert(!gsym->has_plt_offset()); + + this->plt_->reserve_slot(plt_index); + + gsym->set_plt_offset((plt_index + 1) * this->plt_entry_size()); + + unsigned int got_offset = (plt_index + 3) * 8; + this->plt_->add_relocation(gsym, got_offset); +} + // Define the _TLS_MODULE_BASE_ symbol in the TLS segment. void |