X-Git-Url: http://drtracing.org/?a=blobdiff_plain;f=gold%2Fx86_64.cc;h=da5087faad847db3886c55a7052604f755c8b5c7;hb=73b9be8b5301c4ac056e10c38a47414867ee892a;hp=8d494ea175531b00ab4ab3979045c579062f053e;hpb=f571390111e28717935ea1b6edd1afc902c5c61c;p=deliverable%2Fbinutils-gdb.git diff --git a/gold/x86_64.cc b/gold/x86_64.cc index 8d494ea175..da5087faad 100644 --- a/gold/x86_64.cc +++ b/gold/x86_64.cc @@ -1,6 +1,6 @@ // x86_64.cc -- x86_64 target support for gold. -// Copyright (C) 2006-2016 Free Software Foundation, Inc. +// Copyright (C) 2006-2017 Free Software Foundation, Inc. // Written by Ian Lance Taylor . // This file is part of gold. @@ -179,7 +179,12 @@ class Output_data_plt_x86_64 : public Output_section_data has_irelative_section() const { return this->irelative_rel_ != NULL; } - // Return the number of PLT entries. + // Get count of regular PLT entries. + unsigned int + regular_count() const + { return this->count_; } + + // Return the total number of PLT entries. unsigned int entry_count() const { return this->count_ + this->irelative_count_; } @@ -204,11 +209,13 @@ class Output_data_plt_x86_64 : public Output_section_data // Return the PLT address to use for a global symbol. uint64_t - address_for_global(const Symbol*); + address_for_global(const Symbol* sym) + { return do_address_for_global(sym); } // Return the PLT address to use for a local symbol. uint64_t - address_for_local(const Relobj*, unsigned int symndx); + address_for_local(const Relobj* obj, unsigned int symndx) + { return do_address_for_local(obj, symndx); } // Add .eh_frame information for the PLT. void @@ -216,6 +223,18 @@ class Output_data_plt_x86_64 : public Output_section_data { this->do_add_eh_frame(layout); } protected: + Output_data_got<64, false>* + got() const + { return this->got_; } + + Output_data_got_plt_x86_64* + got_plt() const + { return this->got_plt_; } + + Output_data_space* + got_irelative() const + { return this->got_irelative_; } + // Fill in the first PLT entry. void fill_first_plt_entry(unsigned char* pov, @@ -275,6 +294,14 @@ class Output_data_plt_x86_64 : public Output_section_data unsigned int tlsdesc_got_offset, unsigned int plt_offset) = 0; + // Return the PLT address to use for a global symbol. + virtual uint64_t + do_address_for_global(const Symbol* sym); + + // Return the PLT address to use for a local symbol. + virtual uint64_t + do_address_for_local(const Relobj* obj, unsigned int symndx); + virtual void do_add_eh_frame(Layout* layout) = 0; @@ -403,6 +430,118 @@ class Output_data_plt_x86_64_standard : public Output_data_plt_x86_64 static const unsigned char plt_eh_frame_fde[plt_eh_frame_fde_size]; }; +class Output_data_plt_x86_64_bnd : public Output_data_plt_x86_64<64> +{ + public: + Output_data_plt_x86_64_bnd(Layout* layout, + Output_data_got<64, false>* got, + Output_data_got_plt_x86_64* got_plt, + Output_data_space* got_irelative) + : Output_data_plt_x86_64<64>(layout, plt_entry_size, + got, got_plt, got_irelative), + aplt_offset_(0) + { } + + Output_data_plt_x86_64_bnd(Layout* layout, + Output_data_got<64, false>* got, + Output_data_got_plt_x86_64* got_plt, + Output_data_space* got_irelative, + unsigned int plt_count) + : Output_data_plt_x86_64<64>(layout, plt_entry_size, + got, got_plt, got_irelative, + plt_count), + aplt_offset_(0) + { } + + protected: + virtual unsigned int + do_get_plt_entry_size() const + { return plt_entry_size; } + + // Return the PLT address to use for a global symbol. + uint64_t + do_address_for_global(const Symbol*); + + // Return the PLT address to use for a local symbol. + uint64_t + do_address_for_local(const Relobj*, unsigned int symndx); + + virtual void + do_add_eh_frame(Layout* layout) + { + layout->add_eh_frame_for_plt(this, + this->plt_eh_frame_cie, + this->plt_eh_frame_cie_size, + plt_eh_frame_fde, + plt_eh_frame_fde_size); + } + + virtual void + do_fill_first_plt_entry(unsigned char* pov, + elfcpp::Elf_types<64>::Elf_Addr got_addr, + elfcpp::Elf_types<64>::Elf_Addr plt_addr); + + virtual unsigned int + do_fill_plt_entry(unsigned char* pov, + elfcpp::Elf_types<64>::Elf_Addr got_address, + elfcpp::Elf_types<64>::Elf_Addr plt_address, + unsigned int got_offset, + unsigned int plt_offset, + unsigned int plt_index); + + virtual void + do_fill_tlsdesc_entry(unsigned char* pov, + elfcpp::Elf_types<64>::Elf_Addr got_address, + elfcpp::Elf_types<64>::Elf_Addr plt_address, + elfcpp::Elf_types<64>::Elf_Addr got_base, + unsigned int tlsdesc_got_offset, + unsigned int plt_offset); + + void + fill_aplt_entry(unsigned char* pov, + elfcpp::Elf_types<64>::Elf_Addr got_address, + elfcpp::Elf_types<64>::Elf_Addr plt_address, + unsigned int got_offset, + unsigned int plt_offset, + unsigned int plt_index); + + private: + // Set the final size. + void + set_final_data_size(); + + // Write out the BND PLT data. + void + do_write(Output_file*); + + // Offset of the Additional PLT (if using -z bndplt). + unsigned int aplt_offset_; + + // The size of an entry in the PLT. + static const int plt_entry_size = 16; + + // The size of an entry in the additional PLT. + static const int aplt_entry_size = 8; + + // The first entry in the PLT. + // From the AMD64 ABI: "Unlike Intel386 ABI, this ABI uses the same + // procedure linkage table for both programs and shared objects." + static const unsigned char first_plt_entry[plt_entry_size]; + + // Other entries in the PLT for an executable. + static const unsigned char plt_entry[plt_entry_size]; + + // Entries in the additional PLT. + static const unsigned char aplt_entry[aplt_entry_size]; + + // The reserved TLSDESC entry in the PLT for an executable. + static const unsigned char tlsdesc_plt_entry[plt_entry_size]; + + // The .eh_frame unwind information for the PLT. + static const int plt_eh_frame_fde_size = 32; + static const unsigned char plt_eh_frame_fde[plt_eh_frame_fde_size]; +}; + template class Lazy_view { @@ -590,10 +729,13 @@ class Target_x86_64 : public Sized_target // and global_reloc_may_be_function_pointer) // if a function's pointer is taken. ICF uses this in safe mode to only // fold those functions whose pointer is defintely not taken. For x86_64 - // pie binaries, safe ICF cannot be done by looking at relocation types. + // pie binaries, safe ICF cannot be done by looking at only relocation + // types, and for certain cases (e.g. R_X86_64_PC32), the instruction + // opcode is checked as well to distinguish a function call from taking + // a function's pointer. bool do_can_check_for_function_pointers() const - { return !parameters->options().pie(); } + { return true; } // Return the base for a DW_EH_PE_datarel encoding. uint64_t @@ -714,23 +856,14 @@ class Target_x86_64 : public Sized_target do_make_data_plt(Layout* layout, Output_data_got<64, false>* got, Output_data_got_plt_x86_64* got_plt, - Output_data_space* got_irelative) - { - return new Output_data_plt_x86_64_standard(layout, got, got_plt, - got_irelative); - } + Output_data_space* got_irelative); virtual Output_data_plt_x86_64* do_make_data_plt(Layout* layout, Output_data_got<64, false>* got, Output_data_got_plt_x86_64* got_plt, Output_data_space* got_irelative, - unsigned int plt_count) - { - return new Output_data_plt_x86_64_standard(layout, got, got_plt, - got_irelative, - plt_count); - } + unsigned int plt_count); private: // The class which scans relocations. @@ -794,7 +927,10 @@ class Target_x86_64 : public Sized_target check_non_pic(Relobj*, unsigned int r_type, Symbol*); inline bool - possible_function_pointer_reloc(unsigned int r_type); + possible_function_pointer_reloc(Sized_relobj_file* src_obj, + unsigned int src_indx, + unsigned int r_offset, + unsigned int r_type); bool reloc_needs_plt_for_ifunc(Sized_relobj_file*, @@ -916,8 +1052,11 @@ class Target_x86_64 : public Sized_target return false; // We cannot convert references to IFUNC symbols, or to symbols that // are not local to the current module. + // We can't do predefined symbols because they may become undefined + // (e.g., __ehdr_start when the headers aren't mapped to a segment). if (gsym->type() == elfcpp::STT_GNU_IFUNC - || gsym->is_undefined () + || gsym->is_undefined() + || gsym->is_predefined() || gsym->is_from_dynobj() || gsym->is_preemptible()) return false; @@ -1528,7 +1667,7 @@ Output_data_plt_x86_64::rela_irelative(Symbol_table* symtab, template uint64_t -Output_data_plt_x86_64::address_for_global(const Symbol* gsym) +Output_data_plt_x86_64::do_address_for_global(const Symbol* gsym) { uint64_t offset = 0; if (gsym->type() == elfcpp::STT_GNU_IFUNC @@ -1542,8 +1681,8 @@ Output_data_plt_x86_64::address_for_global(const Symbol* gsym) template uint64_t -Output_data_plt_x86_64::address_for_local(const Relobj* object, - unsigned int r_sym) +Output_data_plt_x86_64::do_address_for_local(const Relobj* object, + unsigned int r_sym) { return (this->address() + (this->count_ + 1) * this->get_plt_entry_size() @@ -1555,10 +1694,12 @@ template void Output_data_plt_x86_64::set_final_data_size() { - unsigned int count = this->count_ + this->irelative_count_; + // Number of regular and IFUNC PLT entries, plus the first entry. + unsigned int count = this->count_ + this->irelative_count_ + 1; + // Count the TLSDESC entry, if present. if (this->has_tlsdesc_entry()) ++count; - this->set_data_size((count + 1) * this->get_plt_entry_size()); + this->set_data_size(count * this->get_plt_entry_size()); } // The first entry in the PLT for an executable. @@ -1673,6 +1814,178 @@ Output_data_plt_x86_64_standard::do_fill_tlsdesc_entry( + 12))); } +// Return the APLT address to use for a global symbol (for -z bndplt). + +uint64_t +Output_data_plt_x86_64_bnd::do_address_for_global(const Symbol* gsym) +{ + uint64_t offset = this->aplt_offset_; + // Convert the PLT offset into an APLT offset. + unsigned int plt_offset = gsym->plt_offset(); + if (gsym->type() == elfcpp::STT_GNU_IFUNC + && gsym->can_use_relative_reloc(false)) + offset += this->regular_count() * aplt_entry_size; + else + plt_offset -= plt_entry_size; + plt_offset = plt_offset / (plt_entry_size / aplt_entry_size); + return this->address() + offset + plt_offset; +} + +// Return the PLT address to use for a local symbol. These are always +// IRELATIVE relocs. + +uint64_t +Output_data_plt_x86_64_bnd::do_address_for_local(const Relobj* object, + unsigned int r_sym) +{ + // Convert the PLT offset into an APLT offset. + unsigned int plt_offset = ((object->local_plt_offset(r_sym) - plt_entry_size) + / (plt_entry_size / aplt_entry_size)); + return (this->address() + + this->aplt_offset_ + + this->regular_count() * aplt_entry_size + + plt_offset); +} + +// Set the final size. +void +Output_data_plt_x86_64_bnd::set_final_data_size() +{ + // Number of regular and IFUNC PLT entries. + unsigned int count = this->entry_count(); + // Count the first entry and the TLSDESC entry, if present. + unsigned int extra = this->has_tlsdesc_entry() ? 2 : 1; + unsigned int plt_size = (count + extra) * plt_entry_size; + // Offset of the APLT. + this->aplt_offset_ = plt_size; + // Size of the APLT. + plt_size += count * aplt_entry_size; + this->set_data_size(plt_size); +} + +// The first entry in the BND PLT. + +const unsigned char +Output_data_plt_x86_64_bnd::first_plt_entry[plt_entry_size] = +{ + // From AMD64 ABI Draft 0.98, page 76 + 0xff, 0x35, // pushq contents of memory address + 0, 0, 0, 0, // replaced with address of .got + 8 + 0xf2, 0xff, 0x25, // bnd jmp indirect + 0, 0, 0, 0, // replaced with address of .got + 16 + 0x0f, 0x1f, 0x00 // nop +}; + +void +Output_data_plt_x86_64_bnd::do_fill_first_plt_entry( + unsigned char* pov, + elfcpp::Elf_types<64>::Elf_Addr got_address, + elfcpp::Elf_types<64>::Elf_Addr plt_address) +{ + memcpy(pov, first_plt_entry, plt_entry_size); + // We do a jmp relative to the PC at the end of this instruction. + elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, + (got_address + 8 + - (plt_address + 6))); + elfcpp::Swap<32, false>::writeval(pov + 9, + (got_address + 16 + - (plt_address + 13))); +} + +// Subsequent entries in the BND PLT. + +const unsigned char +Output_data_plt_x86_64_bnd::plt_entry[plt_entry_size] = +{ + // From AMD64 ABI Draft 0.99.8, page 139 + 0x68, // pushq immediate + 0, 0, 0, 0, // replaced with offset into relocation table + 0xf2, 0xe9, // bnd jmpq relative + 0, 0, 0, 0, // replaced with offset to start of .plt + 0x0f, 0x1f, 0x44, 0, 0 // nop +}; + +// Entries in the BND Additional PLT. + +const unsigned char +Output_data_plt_x86_64_bnd::aplt_entry[aplt_entry_size] = +{ + // From AMD64 ABI Draft 0.99.8, page 139 + 0xf2, 0xff, 0x25, // bnd jmpq indirect + 0, 0, 0, 0, // replaced with address of symbol in .got + 0x90, // nop +}; + +unsigned int +Output_data_plt_x86_64_bnd::do_fill_plt_entry( + unsigned char* pov, + elfcpp::Elf_types<64>::Elf_Addr, + elfcpp::Elf_types<64>::Elf_Addr, + unsigned int, + unsigned int plt_offset, + unsigned int plt_index) +{ + memcpy(pov, plt_entry, plt_entry_size); + elfcpp::Swap_unaligned<32, false>::writeval(pov + 1, plt_index); + elfcpp::Swap<32, false>::writeval(pov + 7, -(plt_offset + 11)); + return 0; +} + +void +Output_data_plt_x86_64_bnd::fill_aplt_entry( + unsigned char* pov, + elfcpp::Elf_types<64>::Elf_Addr got_address, + elfcpp::Elf_types<64>::Elf_Addr plt_address, + unsigned int got_offset, + unsigned int plt_offset, + unsigned int plt_index) +{ + // Check PC-relative offset overflow in PLT entry. + uint64_t plt_got_pcrel_offset = (got_address + got_offset + - (plt_address + plt_offset + 7)); + if (Bits<32>::has_overflow(plt_got_pcrel_offset)) + gold_error(_("PC-relative offset overflow in APLT entry %d"), + plt_index + 1); + + memcpy(pov, aplt_entry, aplt_entry_size); + elfcpp::Swap_unaligned<32, false>::writeval(pov + 3, plt_got_pcrel_offset); +} + +// The reserved TLSDESC entry in the PLT for an executable. + +const unsigned char +Output_data_plt_x86_64_bnd::tlsdesc_plt_entry[plt_entry_size] = +{ + // From Alexandre Oliva, "Thread-Local Storage Descriptors for IA32 + // and AMD64/EM64T", Version 0.9.4 (2005-10-10). + 0xff, 0x35, // pushq x(%rip) + 0, 0, 0, 0, // replaced with address of linkmap GOT entry (at PLTGOT + 8) + 0xf2, 0xff, 0x25, // jmpq *y(%rip) + 0, 0, 0, 0, // replaced with offset of reserved TLSDESC_GOT entry + 0x0f, 0x1f, 0 // nop +}; + +void +Output_data_plt_x86_64_bnd::do_fill_tlsdesc_entry( + unsigned char* pov, + elfcpp::Elf_types<64>::Elf_Addr got_address, + elfcpp::Elf_types<64>::Elf_Addr plt_address, + elfcpp::Elf_types<64>::Elf_Addr got_base, + unsigned int tlsdesc_got_offset, + unsigned int plt_offset) +{ + memcpy(pov, tlsdesc_plt_entry, plt_entry_size); + elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, + (got_address + 8 + - (plt_address + plt_offset + + 6))); + elfcpp::Swap_unaligned<32, false>::writeval(pov + 9, + (got_base + + tlsdesc_got_offset + - (plt_address + plt_offset + + 13))); +} + // The .eh_frame unwind information for the PLT. template @@ -1723,6 +2036,34 @@ Output_data_plt_x86_64_standard::plt_eh_frame_fde[plt_eh_frame_fde_size] = elfcpp::DW_CFA_nop }; +// The .eh_frame unwind information for the BND PLT. +const unsigned char +Output_data_plt_x86_64_bnd::plt_eh_frame_fde[plt_eh_frame_fde_size] = +{ + 0, 0, 0, 0, // Replaced with offset to .plt. + 0, 0, 0, 0, // Replaced with size of .plt. + 0, // Augmentation size. + elfcpp::DW_CFA_def_cfa_offset, 16, // DW_CFA_def_cfa_offset: 16. + elfcpp::DW_CFA_advance_loc + 6, // Advance 6 to __PLT__ + 6. + elfcpp::DW_CFA_def_cfa_offset, 24, // DW_CFA_def_cfa_offset: 24. + elfcpp::DW_CFA_advance_loc + 10, // Advance 10 to __PLT__ + 16. + elfcpp::DW_CFA_def_cfa_expression, // DW_CFA_def_cfa_expression. + 11, // Block length. + elfcpp::DW_OP_breg7, 8, // Push %rsp + 8. + elfcpp::DW_OP_breg16, 0, // Push %rip. + elfcpp::DW_OP_lit15, // Push 0xf. + elfcpp::DW_OP_and, // & (%rip & 0xf). + elfcpp::DW_OP_lit5, // Push 5. + elfcpp::DW_OP_ge, // >= ((%rip & 0xf) >= 5) + elfcpp::DW_OP_lit3, // Push 3. + elfcpp::DW_OP_shl, // << (((%rip & 0xf) >= 5) << 3) + elfcpp::DW_OP_plus, // + ((((%rip&0xf)>=5)<<3)+%rsp+8 + elfcpp::DW_CFA_nop, // Align to 32 bytes. + elfcpp::DW_CFA_nop, + elfcpp::DW_CFA_nop, + elfcpp::DW_CFA_nop +}; + // Write out the PLT. This uses the hand-coded instructions above, // and adjusts them as needed. This is specified by the AMD64 ABI. @@ -1802,6 +2143,100 @@ Output_data_plt_x86_64::do_write(Output_file* of) of->write_output_view(got_file_offset, got_size, got_view); } +// Write out the BND PLT. + +void +Output_data_plt_x86_64_bnd::do_write(Output_file* of) +{ + const off_t offset = this->offset(); + const section_size_type oview_size = + convert_to_section_size_type(this->data_size()); + unsigned char* const oview = of->get_output_view(offset, oview_size); + + Output_data_got<64, false>* got = this->got(); + Output_data_got_plt_x86_64* got_plt = this->got_plt(); + Output_data_space* got_irelative = this->got_irelative(); + + const off_t got_file_offset = got_plt->offset(); + gold_assert(parameters->incremental_update() + || (got_file_offset + got_plt->data_size() + == got_irelative->offset())); + const section_size_type got_size = + convert_to_section_size_type(got_plt->data_size() + + got_irelative->data_size()); + unsigned char* const got_view = of->get_output_view(got_file_offset, + got_size); + + unsigned char* pov = oview; + + // The base address of the .plt section. + elfcpp::Elf_types<64>::Elf_Addr plt_address = this->address(); + // The base address of the .got section. + elfcpp::Elf_types<64>::Elf_Addr got_base = got->address(); + // The base address of the PLT portion of the .got section, + // which is where the GOT pointer will point, and where the + // three reserved GOT entries are located. + elfcpp::Elf_types<64>::Elf_Addr got_address = got_plt->address(); + + this->fill_first_plt_entry(pov, got_address, plt_address); + pov += plt_entry_size; + + // The first three entries in the GOT are reserved, and are written + // by Output_data_got_plt_x86_64::do_write. + unsigned char* got_pov = got_view + 24; + + unsigned int plt_offset = plt_entry_size; + unsigned int got_offset = 24; + const unsigned int count = this->entry_count(); + for (unsigned int plt_index = 0; + plt_index < count; + ++plt_index, + pov += plt_entry_size, + got_pov += 8, + plt_offset += plt_entry_size, + got_offset += 8) + { + // Set and adjust the PLT entry itself. + unsigned int lazy_offset = this->fill_plt_entry(pov, + got_address, plt_address, + got_offset, plt_offset, + plt_index); + + // Set the entry in the GOT. + elfcpp::Swap<64, false>::writeval(got_pov, + plt_address + plt_offset + lazy_offset); + } + + if (this->has_tlsdesc_entry()) + { + // Set and adjust the reserved TLSDESC PLT entry. + unsigned int tlsdesc_got_offset = this->get_tlsdesc_got_offset(); + this->fill_tlsdesc_entry(pov, got_address, plt_address, got_base, + tlsdesc_got_offset, plt_offset); + pov += this->get_plt_entry_size(); + } + + // Write the additional PLT. + got_offset = 24; + for (unsigned int plt_index = 0; + plt_index < count; + ++plt_index, + pov += aplt_entry_size, + plt_offset += aplt_entry_size, + got_offset += 8) + { + // Set and adjust the PLT entry itself. + this->fill_aplt_entry(pov, got_address, plt_address, got_offset, + plt_offset, plt_index); + } + + gold_assert(static_cast(pov - oview) == oview_size); + gold_assert(static_cast(got_pov - got_view) == got_size); + + of->write_output_view(offset, oview_size, oview); + of->write_output_view(got_file_offset, got_size, got_view); +} + // Create the PLT section. template @@ -1831,6 +2266,62 @@ Target_x86_64::make_plt_section(Symbol_table* symtab, Layout* layout) } } +template<> +Output_data_plt_x86_64<32>* +Target_x86_64<32>::do_make_data_plt(Layout* layout, + Output_data_got<64, false>* got, + Output_data_got_plt_x86_64* got_plt, + Output_data_space* got_irelative) +{ + return new Output_data_plt_x86_64_standard<32>(layout, got, got_plt, + got_irelative); +} + +template<> +Output_data_plt_x86_64<64>* +Target_x86_64<64>::do_make_data_plt(Layout* layout, + Output_data_got<64, false>* got, + Output_data_got_plt_x86_64* got_plt, + Output_data_space* got_irelative) +{ + if (parameters->options().bndplt()) + return new Output_data_plt_x86_64_bnd(layout, got, got_plt, + got_irelative); + else + return new Output_data_plt_x86_64_standard<64>(layout, got, got_plt, + got_irelative); +} + +template<> +Output_data_plt_x86_64<32>* +Target_x86_64<32>::do_make_data_plt(Layout* layout, + Output_data_got<64, false>* got, + Output_data_got_plt_x86_64* got_plt, + Output_data_space* got_irelative, + unsigned int plt_count) +{ + return new Output_data_plt_x86_64_standard<32>(layout, got, got_plt, + got_irelative, + plt_count); +} + +template<> +Output_data_plt_x86_64<64>* +Target_x86_64<64>::do_make_data_plt(Layout* layout, + Output_data_got<64, false>* got, + Output_data_got_plt_x86_64* got_plt, + Output_data_space* got_irelative, + unsigned int plt_count) +{ + if (parameters->options().bndplt()) + return new Output_data_plt_x86_64_bnd(layout, got, got_plt, + got_irelative, plt_count); + else + return new Output_data_plt_x86_64_standard<64>(layout, got, got_plt, + got_irelative, + plt_count); +} + // Return the section for TLSDESC relocations. template @@ -2361,7 +2852,7 @@ Target_x86_64::Scan::check_non_pic(Relobj* object, unsigned int r_type, && !gsym->is_undefined() && !gsym->is_preemptible())) return; - /* Fall through. */ + // Fall through. case elfcpp::R_X86_64_32: // R_X86_64_32 is OK for x32. if (size == 32 && r_type == elfcpp::R_X86_64_32) @@ -2792,7 +3283,11 @@ Target_x86_64::Scan::unsupported_reloc_global( // Returns true if this relocation type could be that of a function pointer. template inline bool -Target_x86_64::Scan::possible_function_pointer_reloc(unsigned int r_type) +Target_x86_64::Scan::possible_function_pointer_reloc( + Sized_relobj_file* src_obj, + unsigned int src_indx, + unsigned int r_offset, + unsigned int r_type) { switch (r_type) { @@ -2811,6 +3306,41 @@ Target_x86_64::Scan::possible_function_pointer_reloc(unsigned int r_type) { return true; } + case elfcpp::R_X86_64_PC32: + { + // This relocation may be used both for function calls and + // for taking address of a function. We distinguish between + // them by checking the opcodes. + uint64_t sh_flags = src_obj->section_flags(src_indx); + bool is_executable = (sh_flags & elfcpp::SHF_EXECINSTR) != 0; + if (is_executable) + { + section_size_type stype; + const unsigned char* view = src_obj->section_contents(src_indx, + &stype, + true); + + // call + if (r_offset >= 1 + && view[r_offset - 1] == 0xe8) + return false; + + // jmp + if (r_offset >= 1 + && view[r_offset - 1] == 0xe9) + return false; + + // jo/jno/jb/jnb/je/jne/jna/ja/js/jns/jp/jnp/jl/jge/jle/jg + if (r_offset >= 2 + && view[r_offset - 2] == 0x0f + && view[r_offset - 1] >= 0x80 + && view[r_offset - 1] <= 0x8f) + return false; + } + + // Be conservative and treat all others as function pointers. + return true; + } } return false; } @@ -2825,18 +3355,21 @@ Target_x86_64::Scan::local_reloc_may_be_function_pointer( Symbol_table* , Layout* , Target_x86_64* , - Sized_relobj_file* , - unsigned int , + Sized_relobj_file* src_obj, + unsigned int src_indx, Output_section* , - const elfcpp::Rela& , + const elfcpp::Rela& reloc, unsigned int r_type, const elfcpp::Sym&) { // When building a shared library, do not fold any local symbols as it is // not possible to distinguish pointer taken versus a call by looking at // the relocation types. - return (parameters->options().shared() - || possible_function_pointer_reloc(r_type)); + if (parameters->options().shared()) + return true; + + return possible_function_pointer_reloc(src_obj, src_indx, + reloc.get_r_offset(), r_type); } // For safe ICF, scan a relocation for a global symbol to check if it @@ -2849,20 +3382,23 @@ Target_x86_64::Scan::global_reloc_may_be_function_pointer( Symbol_table*, Layout* , Target_x86_64* , - Sized_relobj_file* , - unsigned int , + Sized_relobj_file* src_obj, + unsigned int src_indx, Output_section* , - const elfcpp::Rela& , + const elfcpp::Rela& reloc, unsigned int r_type, Symbol* gsym) { // When building a shared library, do not fold symbols whose visibility // is hidden, internal or protected. - return ((parameters->options().shared() - && (gsym->visibility() == elfcpp::STV_INTERNAL - || gsym->visibility() == elfcpp::STV_PROTECTED - || gsym->visibility() == elfcpp::STV_HIDDEN)) - || possible_function_pointer_reloc(r_type)); + if (parameters->options().shared() + && (gsym->visibility() == elfcpp::STV_INTERNAL + || gsym->visibility() == elfcpp::STV_PROTECTED + || gsym->visibility() == elfcpp::STV_HIDDEN)) + return true; + + return possible_function_pointer_reloc(src_obj, src_indx, + reloc.get_r_offset(), r_type); } // Scan a relocation for a global symbol. @@ -3675,7 +4211,7 @@ Target_x86_64::Relocate::relocate( case elfcpp::R_X86_64_GOT64: case elfcpp::R_X86_64_GOTPLT64: - // R_X86_64_GOTPLT64 is obsolete and treated the the same as + // R_X86_64_GOTPLT64 is obsolete and treated the same as // GOT64. gold_assert(have_got_offset); Reloc_funcs::rela64(view, got_offset, addend); @@ -3762,12 +4298,14 @@ Target_x86_64::Relocate::relocate( if (gsym != NULL) { gold_assert(gsym->has_got_offset(GOT_TYPE_STANDARD)); - got_offset = gsym->got_offset(GOT_TYPE_STANDARD) - target->got_size(); + got_offset = (gsym->got_offset(GOT_TYPE_STANDARD) + - target->got_size()); } else { unsigned int r_sym = elfcpp::elf_r_sym(rela.get_r_info()); - gold_assert(object->local_has_got_offset(r_sym, GOT_TYPE_STANDARD)); + 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()); }