// arm.cc -- arm target support for gold. // Copyright 2009 Free Software Foundation, Inc. // Written by Doug Kwan based on the i386 code // by Ian Lance Taylor . // This file also contains borrowed and adapted code from // bfd/elf32-arm.c. // This file is part of gold. // This program is free software; you can redistribute it and/or modify // it under the terms of the GNU General Public License as published by // the Free Software Foundation; either version 3 of the License, or // (at your option) any later version. // This program is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // You should have received a copy of the GNU General Public License // along with this program; if not, write to the Free Software // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, // MA 02110-1301, USA. #include "gold.h" #include #include #include #include #include #include "elfcpp.h" #include "parameters.h" #include "reloc.h" #include "arm.h" #include "object.h" #include "symtab.h" #include "layout.h" #include "output.h" #include "copy-relocs.h" #include "target.h" #include "target-reloc.h" #include "target-select.h" #include "tls.h" #include "defstd.h" #include "gc.h" namespace { using namespace gold; template class Output_data_plt_arm; template class Stub_table; template class Arm_input_section; template class Arm_output_section; template class Arm_relobj; template class Target_arm; // For convenience. typedef elfcpp::Elf_types<32>::Elf_Addr Arm_address; // Maximum branch offsets for ARM, THUMB and THUMB2. const int32_t ARM_MAX_FWD_BRANCH_OFFSET = ((((1 << 23) - 1) << 2) + 8); const int32_t ARM_MAX_BWD_BRANCH_OFFSET = ((-((1 << 23) << 2)) + 8); const int32_t THM_MAX_FWD_BRANCH_OFFSET = ((1 << 22) -2 + 4); const int32_t THM_MAX_BWD_BRANCH_OFFSET = (-(1 << 22) + 4); const int32_t THM2_MAX_FWD_BRANCH_OFFSET = (((1 << 24) - 2) + 4); const int32_t THM2_MAX_BWD_BRANCH_OFFSET = (-(1 << 24) + 4); // The arm target class. // // This is a very simple port of gold for ARM-EABI. It is intended for // supporting Android only for the time being. Only these relocation types // are supported. // // R_ARM_NONE // R_ARM_ABS32 // R_ARM_ABS32_NOI // R_ARM_ABS16 // R_ARM_ABS12 // R_ARM_ABS8 // R_ARM_THM_ABS5 // R_ARM_BASE_ABS // R_ARM_REL32 // R_ARM_THM_CALL // R_ARM_COPY // R_ARM_GLOB_DAT // R_ARM_BASE_PREL // R_ARM_JUMP_SLOT // R_ARM_RELATIVE // R_ARM_GOTOFF32 // R_ARM_GOT_BREL // R_ARM_GOT_PREL // R_ARM_PLT32 // R_ARM_CALL // R_ARM_JUMP24 // R_ARM_TARGET1 // R_ARM_PREL31 // R_ARM_ABS8 // R_ARM_MOVW_ABS_NC // R_ARM_MOVT_ABS // R_ARM_THM_MOVW_ABS_NC // R_ARM_THM_MOVT_ABS // R_ARM_MOVW_PREL_NC // R_ARM_MOVT_PREL // R_ARM_THM_MOVW_PREL_NC // R_ARM_THM_MOVT_PREL // // TODOs: // - Generate various branch stubs. // - Support interworking. // - Define section symbols __exidx_start and __exidx_stop. // - Support more relocation types as needed. // - Make PLTs more flexible for different architecture features like // Thumb-2 and BE8. // There are probably a lot more. // Instruction template class. This class is similar to the insn_sequence // struct in bfd/elf32-arm.c. class Insn_template { public: // Types of instruction templates. enum Type { THUMB16_TYPE = 1, THUMB32_TYPE, ARM_TYPE, DATA_TYPE }; // Factory methods to create instrunction templates in different formats. static const Insn_template thumb16_insn(uint32_t data) { return Insn_template(data, THUMB16_TYPE, elfcpp::R_ARM_NONE, 0); } // A bit of a hack. A Thumb conditional branch, in which the proper // condition is inserted when we build the stub. static const Insn_template thumb16_bcond_insn(uint32_t data) { return Insn_template(data, THUMB16_TYPE, elfcpp::R_ARM_NONE, 1); } static const Insn_template thumb32_insn(uint32_t data) { return Insn_template(data, THUMB32_TYPE, elfcpp::R_ARM_NONE, 0); } static const Insn_template thumb32_b_insn(uint32_t data, int reloc_addend) { return Insn_template(data, THUMB32_TYPE, elfcpp::R_ARM_THM_JUMP24, reloc_addend); } static const Insn_template arm_insn(uint32_t data) { return Insn_template(data, ARM_TYPE, elfcpp::R_ARM_NONE, 0); } static const Insn_template arm_rel_insn(unsigned data, int reloc_addend) { return Insn_template(data, ARM_TYPE, elfcpp::R_ARM_JUMP24, reloc_addend); } static const Insn_template data_word(unsigned data, unsigned int r_type, int reloc_addend) { return Insn_template(data, DATA_TYPE, r_type, reloc_addend); } // Accessors. This class is used for read-only objects so no modifiers // are provided. uint32_t data() const { return this->data_; } // Return the instruction sequence type of this. Type type() const { return this->type_; } // Return the ARM relocation type of this. unsigned int r_type() const { return this->r_type_; } int32_t reloc_addend() const { return this->reloc_addend_; } // Return size of instrunction template in bytes. size_t size() const; // Return byte-alignment of instrunction template. unsigned alignment() const; private: // We make the constructor private to ensure that only the factory // methods are used. inline Insn_template(unsigned data, Type type, unsigned int r_type, int reloc_addend) : data_(data), type_(type), r_type_(r_type), reloc_addend_(reloc_addend) { } // Instruction specific data. This is used to store information like // some of the instruction bits. uint32_t data_; // Instruction template type. Type type_; // Relocation type if there is a relocation or R_ARM_NONE otherwise. unsigned int r_type_; // Relocation addend. int32_t reloc_addend_; }; // Macro for generating code to stub types. One entry per long/short // branch stub #define DEF_STUBS \ DEF_STUB(long_branch_any_any) \ DEF_STUB(long_branch_v4t_arm_thumb) \ DEF_STUB(long_branch_thumb_only) \ DEF_STUB(long_branch_v4t_thumb_thumb) \ DEF_STUB(long_branch_v4t_thumb_arm) \ DEF_STUB(short_branch_v4t_thumb_arm) \ DEF_STUB(long_branch_any_arm_pic) \ DEF_STUB(long_branch_any_thumb_pic) \ DEF_STUB(long_branch_v4t_thumb_thumb_pic) \ DEF_STUB(long_branch_v4t_arm_thumb_pic) \ DEF_STUB(long_branch_v4t_thumb_arm_pic) \ DEF_STUB(long_branch_thumb_only_pic) \ DEF_STUB(a8_veneer_b_cond) \ DEF_STUB(a8_veneer_b) \ DEF_STUB(a8_veneer_bl) \ DEF_STUB(a8_veneer_blx) // Stub types. #define DEF_STUB(x) arm_stub_##x, typedef enum { arm_stub_none, DEF_STUBS // First reloc stub type. arm_stub_reloc_first = arm_stub_long_branch_any_any, // Last reloc stub type. arm_stub_reloc_last = arm_stub_long_branch_thumb_only_pic, // First Cortex-A8 stub type. arm_stub_cortex_a8_first = arm_stub_a8_veneer_b_cond, // Last Cortex-A8 stub type. arm_stub_cortex_a8_last = arm_stub_a8_veneer_blx, // Last stub type. arm_stub_type_last = arm_stub_a8_veneer_blx } Stub_type; #undef DEF_STUB // Stub template class. Templates are meant to be read-only objects. // A stub template for a stub type contains all read-only attributes // common to all stubs of the same type. class Stub_template { public: Stub_template(Stub_type, const Insn_template*, size_t); ~Stub_template() { } // Return stub type. Stub_type type() const { return this->type_; } // Return an array of instruction templates. const Insn_template* insns() const { return this->insns_; } // Return size of template in number of instructions. size_t insn_count() const { return this->insn_count_; } // Return size of template in bytes. size_t size() const { return this->size_; } // Return alignment of the stub template. unsigned alignment() const { return this->alignment_; } // Return whether entry point is in thumb mode. bool entry_in_thumb_mode() const { return this->entry_in_thumb_mode_; } // Return number of relocations in this template. size_t reloc_count() const { return this->relocs_.size(); } // Return index of the I-th instruction with relocation. size_t reloc_insn_index(size_t i) const { gold_assert(i < this->relocs_.size()); return this->relocs_[i].first; } // Return the offset of the I-th instruction with relocation from the // beginning of the stub. section_size_type reloc_offset(size_t i) const { gold_assert(i < this->relocs_.size()); return this->relocs_[i].second; } private: // This contains information about an instruction template with a relocation // and its offset from start of stub. typedef std::pair Reloc; // A Stub_template may not be copied. We want to share templates as much // as possible. Stub_template(const Stub_template&); Stub_template& operator=(const Stub_template&); // Stub type. Stub_type type_; // Points to an array of Insn_templates. const Insn_template* insns_; // Number of Insn_templates in insns_[]. size_t insn_count_; // Size of templated instructions in bytes. size_t size_; // Alignment of templated instructions. unsigned alignment_; // Flag to indicate if entry is in thumb mode. bool entry_in_thumb_mode_; // A table of reloc instruction indices and offsets. We can find these by // looking at the instruction templates but we pre-compute and then stash // them here for speed. std::vector relocs_; }; // // A class for code stubs. This is a base class for different type of // stubs used in the ARM target. // class Stub { private: static const section_offset_type invalid_offset = static_cast(-1); public: Stub(const Stub_template* stub_template) : stub_template_(stub_template), offset_(invalid_offset) { } virtual ~Stub() { } // Return the stub template. const Stub_template* stub_template() const { return this->stub_template_; } // Return offset of code stub from beginning of its containing stub table. section_offset_type offset() const { gold_assert(this->offset_ != invalid_offset); return this->offset_; } // Set offset of code stub from beginning of its containing stub table. void set_offset(section_offset_type offset) { this->offset_ = offset; } // Return the relocation target address of the i-th relocation in the // stub. This must be defined in a child class. Arm_address reloc_target(size_t i) { return this->do_reloc_target(i); } // Write a stub at output VIEW. BIG_ENDIAN select how a stub is written. void write(unsigned char* view, section_size_type view_size, bool big_endian) { this->do_write(view, view_size, big_endian); } protected: // This must be defined in the child class. virtual Arm_address do_reloc_target(size_t) = 0; // This must be defined in the child class. virtual void do_write(unsigned char*, section_size_type, bool) = 0; private: // Its template. const Stub_template* stub_template_; // Offset within the section of containing this stub. section_offset_type offset_; }; // Reloc stub class. These are stubs we use to fix up relocation because // of limited branch ranges. class Reloc_stub : public Stub { public: static const unsigned int invalid_index = static_cast(-1); // We assume we never jump to this address. static const Arm_address invalid_address = static_cast(-1); // Return destination address. Arm_address destination_address() const { gold_assert(this->destination_address_ != this->invalid_address); return this->destination_address_; } // Set destination address. void set_destination_address(Arm_address address) { gold_assert(address != this->invalid_address); this->destination_address_ = address; } // Reset destination address. void reset_destination_address() { this->destination_address_ = this->invalid_address; } // Determine stub type for a branch of a relocation of R_TYPE going // from BRANCH_ADDRESS to BRANCH_TARGET. If TARGET_IS_THUMB is set, // the branch target is a thumb instruction. TARGET is used for look // up ARM-specific linker settings. static Stub_type stub_type_for_reloc(unsigned int r_type, Arm_address branch_address, Arm_address branch_target, bool target_is_thumb); // Reloc_stub key. A key is logically a triplet of a stub type, a symbol // and an addend. Since we treat global and local symbol differently, we // use a Symbol object for a global symbol and a object-index pair for // a local symbol. class Key { public: // If SYMBOL is not null, this is a global symbol, we ignore RELOBJ and // R_SYM. Otherwise, this is a local symbol and RELOBJ must non-NULL // and R_SYM must not be invalid_index. Key(Stub_type stub_type, const Symbol* symbol, const Relobj* relobj, unsigned int r_sym, int32_t addend) : stub_type_(stub_type), addend_(addend) { if (symbol != NULL) { this->r_sym_ = Reloc_stub::invalid_index; this->u_.symbol = symbol; } else { gold_assert(relobj != NULL && r_sym != invalid_index); this->r_sym_ = r_sym; this->u_.relobj = relobj; } } ~Key() { } // Accessors: Keys are meant to be read-only object so no modifiers are // provided. // Return stub type. Stub_type stub_type() const { return this->stub_type_; } // Return the local symbol index or invalid_index. unsigned int r_sym() const { return this->r_sym_; } // Return the symbol if there is one. const Symbol* symbol() const { return this->r_sym_ == invalid_index ? this->u_.symbol : NULL; } // Return the relobj if there is one. const Relobj* relobj() const { return this->r_sym_ != invalid_index ? this->u_.relobj : NULL; } // Whether this equals to another key k. bool eq(const Key& k) const { return ((this->stub_type_ == k.stub_type_) && (this->r_sym_ == k.r_sym_) && ((this->r_sym_ != Reloc_stub::invalid_index) ? (this->u_.relobj == k.u_.relobj) : (this->u_.symbol == k.u_.symbol)) && (this->addend_ == k.addend_)); } // Return a hash value. size_t hash_value() const { return (this->stub_type_ ^ this->r_sym_ ^ gold::string_hash( (this->r_sym_ != Reloc_stub::invalid_index) ? this->u_.relobj->name().c_str() : this->u_.symbol->name()) ^ this->addend_); } // Functors for STL associative containers. struct hash { size_t operator()(const Key& k) const { return k.hash_value(); } }; struct equal_to { bool operator()(const Key& k1, const Key& k2) const { return k1.eq(k2); } }; // Name of key. This is mainly for debugging. std::string name() const; private: // Stub type. Stub_type stub_type_; // If this is a local symbol, this is the index in the defining object. // Otherwise, it is invalid_index for a global symbol. unsigned int r_sym_; // If r_sym_ is invalid index. This points to a global symbol. // Otherwise, this points a relobj. We used the unsized and target // independent Symbol and Relobj classes instead of Sized_symbol<32> and // Arm_relobj. This is done to avoid making the stub class a template // as most of the stub machinery is endianity-neutral. However, it // may require a bit of casting done by users of this class. union { const Symbol* symbol; const Relobj* relobj; } u_; // Addend associated with a reloc. int32_t addend_; }; protected: // Reloc_stubs are created via a stub factory. So these are protected. Reloc_stub(const Stub_template* stub_template) : Stub(stub_template), destination_address_(invalid_address) { } ~Reloc_stub() { } friend class Stub_factory; private: // Return the relocation target address of the i-th relocation in the // stub. Arm_address do_reloc_target(size_t i) { // All reloc stub have only one relocation. gold_assert(i == 0); return this->destination_address_; } // A template to implement do_write below. template void inline do_fixed_endian_write(unsigned char*, section_size_type); // Write a stub. void do_write(unsigned char* view, section_size_type view_size, bool big_endian); // Address of destination. Arm_address destination_address_; }; // Stub factory class. class Stub_factory { public: // Return the unique instance of this class. static const Stub_factory& get_instance() { static Stub_factory singleton; return singleton; } // Make a relocation stub. Reloc_stub* make_reloc_stub(Stub_type stub_type) const { gold_assert(stub_type >= arm_stub_reloc_first && stub_type <= arm_stub_reloc_last); return new Reloc_stub(this->stub_templates_[stub_type]); } private: // Constructor and destructor are protected since we only return a single // instance created in Stub_factory::get_instance(). Stub_factory(); // A Stub_factory may not be copied since it is a singleton. Stub_factory(const Stub_factory&); Stub_factory& operator=(Stub_factory&); // Stub templates. These are initialized in the constructor. const Stub_template* stub_templates_[arm_stub_type_last+1]; }; // A class to hold stubs for the ARM target. template class Stub_table : public Output_data { public: Stub_table(Arm_input_section* owner) : Output_data(), addralign_(1), owner_(owner), has_been_changed_(false), reloc_stubs_() { } ~Stub_table() { } // Owner of this stub table. Arm_input_section* owner() const { return this->owner_; } // Whether this stub table is empty. bool empty() const { return this->reloc_stubs_.empty(); } // Whether this has been changed. bool has_been_changed() const { return this->has_been_changed_; } // Set the has-been-changed flag. void set_has_been_changed(bool value) { this->has_been_changed_ = value; } // Return the current data size. off_t current_data_size() const { return this->current_data_size_for_child(); } // Add a STUB with using KEY. Caller is reponsible for avoid adding // if already a STUB with the same key has been added. void add_reloc_stub(Reloc_stub* stub, const Reloc_stub::Key& key); // Look up a relocation stub using KEY. Return NULL if there is none. Reloc_stub* find_reloc_stub(const Reloc_stub::Key& key) const { typename Reloc_stub_map::const_iterator p = this->reloc_stubs_.find(key); return (p != this->reloc_stubs_.end()) ? p->second : NULL; } // Relocate stubs in this stub table. void relocate_stubs(const Relocate_info<32, big_endian>*, Target_arm*, Output_section*, unsigned char*, Arm_address, section_size_type); protected: // Write out section contents. void do_write(Output_file*); // Return the required alignment. uint64_t do_addralign() const { return this->addralign_; } // Finalize data size. void set_final_data_size() { this->set_data_size(this->current_data_size_for_child()); } // Reset address and file offset. void do_reset_address_and_file_offset(); private: // Unordered map of stubs. typedef Unordered_map Reloc_stub_map; // Address alignment uint64_t addralign_; // Owner of this stub table. Arm_input_section* owner_; // This is set to true during relaxiong if the size of the stub table // has been changed. bool has_been_changed_; // The relocation stubs. Reloc_stub_map reloc_stubs_; }; // A class to wrap an ordinary input section containing executable code. template class Arm_input_section : public Output_relaxed_input_section { public: Arm_input_section(Relobj* relobj, unsigned int shndx) : Output_relaxed_input_section(relobj, shndx, 1), original_addralign_(1), original_size_(0), stub_table_(NULL) { } ~Arm_input_section() { } // Initialize. void init(); // Whether this is a stub table owner. bool is_stub_table_owner() const { return this->stub_table_ != NULL && this->stub_table_->owner() == this; } // Return the stub table. Stub_table* stub_table() const { return this->stub_table_; } // Set the stub_table. void set_stub_table(Stub_table* stub_table) { this->stub_table_ = stub_table; } // Downcast a base pointer to an Arm_input_section pointer. This is // not type-safe but we only use Arm_input_section not the base class. static Arm_input_section* as_arm_input_section(Output_relaxed_input_section* poris) { return static_cast*>(poris); } protected: // Write data to output file. void do_write(Output_file*); // Return required alignment of this. uint64_t do_addralign() const { if (this->is_stub_table_owner()) return std::max(this->stub_table_->addralign(), this->original_addralign_); else return this->original_addralign_; } // Finalize data size. void set_final_data_size(); // Reset address and file offset. void do_reset_address_and_file_offset(); // Output offset. bool do_output_offset(const Relobj* object, unsigned int shndx, section_offset_type offset, section_offset_type* poutput) const { if ((object == this->relobj()) && (shndx == this->shndx()) && (offset >= 0) && (convert_types(offset) <= this->original_size_)) { *poutput = offset; return true; } else return false; } private: // Copying is not allowed. Arm_input_section(const Arm_input_section&); Arm_input_section& operator=(const Arm_input_section&); // Address alignment of the original input section. uint64_t original_addralign_; // Section size of the original input section. uint64_t original_size_; // Stub table. Stub_table* stub_table_; }; // Arm output section class. This is defined mainly to add a number of // stub generation methods. template class Arm_output_section : public Output_section { public: Arm_output_section(const char* name, elfcpp::Elf_Word type, elfcpp::Elf_Xword flags) : Output_section(name, type, flags) { } ~Arm_output_section() { } // Group input sections for stub generation. void group_sections(section_size_type, bool, Target_arm*); // Downcast a base pointer to an Arm_output_section pointer. This is // not type-safe but we only use Arm_output_section not the base class. static Arm_output_section* as_arm_output_section(Output_section* os) { return static_cast*>(os); } private: // For convenience. typedef Output_section::Input_section Input_section; typedef Output_section::Input_section_list Input_section_list; // Create a stub group. void create_stub_group(Input_section_list::const_iterator, Input_section_list::const_iterator, Input_section_list::const_iterator, Target_arm*, std::vector*); }; // Arm_relobj class. template class Arm_relobj : public Sized_relobj<32, big_endian> { public: static const Arm_address invalid_address = static_cast(-1); Arm_relobj(const std::string& name, Input_file* input_file, off_t offset, const typename elfcpp::Ehdr<32, big_endian>& ehdr) : Sized_relobj<32, big_endian>(name, input_file, offset, ehdr), stub_tables_(), local_symbol_is_thumb_function_() { } ~Arm_relobj() { } // Return the stub table of the SHNDX-th section if there is one. Stub_table* stub_table(unsigned int shndx) const { gold_assert(shndx < this->stub_tables_.size()); return this->stub_tables_[shndx]; } // Set STUB_TABLE to be the stub_table of the SHNDX-th section. void set_stub_table(unsigned int shndx, Stub_table* stub_table) { gold_assert(shndx < this->stub_tables_.size()); this->stub_tables_[shndx] = stub_table; } // Whether a local symbol is a THUMB function. R_SYM is the symbol table // index. This is only valid after do_count_local_symbol is called. bool local_symbol_is_thumb_function(unsigned int r_sym) const { gold_assert(r_sym < this->local_symbol_is_thumb_function_.size()); return this->local_symbol_is_thumb_function_[r_sym]; } // Scan all relocation sections for stub generation. void scan_sections_for_stubs(Target_arm*, const Symbol_table*, const Layout*); // Convert regular input section with index SHNDX to a relaxed section. void convert_input_section_to_relaxed_section(unsigned shndx) { // The stubs have relocations and we need to process them after writing // out the stubs. So relocation now must follow section write. this->invalidate_section_offset(shndx); this->set_relocs_must_follow_section_writes(); } // Downcast a base pointer to an Arm_relobj pointer. This is // not type-safe but we only use Arm_relobj not the base class. static Arm_relobj* as_arm_relobj(Relobj* relobj) { return static_cast*>(relobj); } // Processor-specific flags in ELF file header. This is valid only after // reading symbols. elfcpp::Elf_Word processor_specific_flags() const { return this->processor_specific_flags_; } protected: // Post constructor setup. void do_setup() { // Call parent's setup method. Sized_relobj<32, big_endian>::do_setup(); // Initialize look-up tables. Stub_table_list empty_stub_table_list(this->shnum(), NULL); this->stub_tables_.swap(empty_stub_table_list); } // Count the local symbols. void do_count_local_symbols(Stringpool_template*, Stringpool_template*); void do_relocate_sections(const Symbol_table* symtab, const Layout* layout, const unsigned char* pshdrs, typename Sized_relobj<32, big_endian>::Views* pivews); // Read the symbol information. void do_read_symbols(Read_symbols_data* sd); private: // List of stub tables. typedef std::vector*> Stub_table_list; Stub_table_list stub_tables_; // Bit vector to tell if a local symbol is a thumb function or not. // This is only valid after do_count_local_symbol is called. std::vector local_symbol_is_thumb_function_; // processor-specific flags in ELF file header. elfcpp::Elf_Word processor_specific_flags_; }; // Arm_dynobj class. template class Arm_dynobj : public Sized_dynobj<32, big_endian> { public: Arm_dynobj(const std::string& name, Input_file* input_file, off_t offset, const elfcpp::Ehdr<32, big_endian>& ehdr) : Sized_dynobj<32, big_endian>(name, input_file, offset, ehdr), processor_specific_flags_(0) { } ~Arm_dynobj() { } // Downcast a base pointer to an Arm_relobj pointer. This is // not type-safe but we only use Arm_relobj not the base class. static Arm_dynobj* as_arm_dynobj(Dynobj* dynobj) { return static_cast*>(dynobj); } // Processor-specific flags in ELF file header. This is valid only after // reading symbols. elfcpp::Elf_Word processor_specific_flags() const { return this->processor_specific_flags_; } protected: // Read the symbol information. void do_read_symbols(Read_symbols_data* sd); private: // processor-specific flags in ELF file header. elfcpp::Elf_Word processor_specific_flags_; }; // Functor to read reloc addends during stub generation. template struct Stub_addend_reader { // Return the addend for a relocation of a particular type. Depending // on whether this is a REL or RELA relocation, read the addend from a // view or from a Reloc object. elfcpp::Elf_types<32>::Elf_Swxword operator()( unsigned int /* r_type */, const unsigned char* /* view */, const typename Reloc_types::Reloc& /* reloc */) const; }; // Specialized Stub_addend_reader for SHT_REL type relocation sections. template struct Stub_addend_reader { elfcpp::Elf_types<32>::Elf_Swxword operator()( unsigned int, const unsigned char*, const typename Reloc_types::Reloc&) const; }; // Specialized Stub_addend_reader for RELA type relocation sections. // We currently do not handle RELA type relocation sections but it is trivial // to implement the addend reader. This is provided for completeness and to // make it easier to add support for RELA relocation sections in the future. template struct Stub_addend_reader { elfcpp::Elf_types<32>::Elf_Swxword operator()( unsigned int, const unsigned char*, const typename Reloc_types::Reloc& reloc) const { return reloc.get_r_addend(); } }; // Utilities for manipulating integers of up to 32-bits namespace utils { // Sign extend an n-bit unsigned integer stored in an uint32_t into // an int32_t. NO_BITS must be between 1 to 32. template static inline int32_t sign_extend(uint32_t bits) { gold_assert(no_bits >= 0 && no_bits <= 32); if (no_bits == 32) return static_cast(bits); uint32_t mask = (~((uint32_t) 0)) >> (32 - no_bits); bits &= mask; uint32_t top_bit = 1U << (no_bits - 1); int32_t as_signed = static_cast(bits); return (bits & top_bit) ? as_signed + (-top_bit * 2) : as_signed; } // Detects overflow of an NO_BITS integer stored in a uint32_t. template static inline bool has_overflow(uint32_t bits) { gold_assert(no_bits >= 0 && no_bits <= 32); if (no_bits == 32) return false; int32_t max = (1 << (no_bits - 1)) - 1; int32_t min = -(1 << (no_bits - 1)); int32_t as_signed = static_cast(bits); return as_signed > max || as_signed < min; } // Detects overflow of an NO_BITS integer stored in a uint32_t when it // fits in the given number of bits as either a signed or unsigned value. // For example, has_signed_unsigned_overflow<8> would check // -128 <= bits <= 255 template static inline bool has_signed_unsigned_overflow(uint32_t bits) { gold_assert(no_bits >= 2 && no_bits <= 32); if (no_bits == 32) return false; int32_t max = static_cast((1U << no_bits) - 1); int32_t min = -(1 << (no_bits - 1)); int32_t as_signed = static_cast(bits); return as_signed > max || as_signed < min; } // Select bits from A and B using bits in MASK. For each n in [0..31], // the n-th bit in the result is chosen from the n-th bits of A and B. // A zero selects A and a one selects B. static inline uint32_t bit_select(uint32_t a, uint32_t b, uint32_t mask) { return (a & ~mask) | (b & mask); } }; template class Target_arm : public Sized_target<32, big_endian> { public: typedef Output_data_reloc Reloc_section; // When were are relocating a stub, we pass this as the relocation number. static const size_t fake_relnum_for_stubs = static_cast(-1); Target_arm() : Sized_target<32, big_endian>(&arm_info), got_(NULL), plt_(NULL), got_plt_(NULL), rel_dyn_(NULL), copy_relocs_(elfcpp::R_ARM_COPY), dynbss_(NULL), stub_tables_(), stub_factory_(Stub_factory::get_instance()), may_use_blx_(true), should_force_pic_veneer_(false), arm_input_section_map_() { } // Whether we can use BLX. bool may_use_blx() const { return this->may_use_blx_; } // Set use-BLX flag. void set_may_use_blx(bool value) { this->may_use_blx_ = value; } // Whether we force PCI branch veneers. bool should_force_pic_veneer() const { return this->should_force_pic_veneer_; } // Set PIC veneer flag. void set_should_force_pic_veneer(bool value) { this->should_force_pic_veneer_ = value; } // Whether we use THUMB-2 instructions. bool using_thumb2() const { // FIXME: This should not hard-coded. return false; } // Whether we use THUMB/THUMB-2 instructions only. bool using_thumb_only() const { // FIXME: This should not hard-coded. return false; } // Whether we have an NOP instruction. If not, use mov r0, r0 instead. bool may_use_arm_nop() const { // FIXME: This should not hard-coded. return false; } // Process the relocations to determine unreferenced sections for // garbage collection. void gc_process_relocs(Symbol_table* symtab, Layout* layout, Sized_relobj<32, big_endian>* object, unsigned int data_shndx, unsigned int sh_type, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, bool needs_special_offset_handling, size_t local_symbol_count, const unsigned char* plocal_symbols); // Scan the relocations to look for symbol adjustments. void scan_relocs(Symbol_table* symtab, Layout* layout, Sized_relobj<32, big_endian>* object, unsigned int data_shndx, unsigned int sh_type, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, bool needs_special_offset_handling, size_t local_symbol_count, const unsigned char* plocal_symbols); // Finalize the sections. void do_finalize_sections(Layout*, const Input_objects*); // Return the value to use for a dynamic symbol which requires special // treatment. uint64_t do_dynsym_value(const Symbol*) const; // Relocate a section. void relocate_section(const Relocate_info<32, big_endian>*, unsigned int sh_type, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, bool needs_special_offset_handling, unsigned char* view, Arm_address view_address, section_size_type view_size, const Reloc_symbol_changes*); // Scan the relocs during a relocatable link. void scan_relocatable_relocs(Symbol_table* symtab, Layout* layout, Sized_relobj<32, big_endian>* object, unsigned int data_shndx, unsigned int sh_type, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, bool needs_special_offset_handling, size_t local_symbol_count, const unsigned char* plocal_symbols, Relocatable_relocs*); // Relocate a section during a relocatable link. void relocate_for_relocatable(const Relocate_info<32, big_endian>*, unsigned int sh_type, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, off_t offset_in_output_section, const Relocatable_relocs*, unsigned char* view, Arm_address view_address, section_size_type view_size, unsigned char* reloc_view, section_size_type reloc_view_size); // Return whether SYM is defined by the ABI. bool do_is_defined_by_abi(Symbol* sym) const { return strcmp(sym->name(), "__tls_get_addr") == 0; } // Return the size of the GOT section. section_size_type got_size() { gold_assert(this->got_ != NULL); return this->got_->data_size(); } // Map platform-specific reloc types static unsigned int get_real_reloc_type (unsigned int r_type); // // Methods to support stub-generations. // // Return the stub factory const Stub_factory& stub_factory() const { return this->stub_factory_; } // Make a new Arm_input_section object. Arm_input_section* new_arm_input_section(Relobj*, unsigned int); // Find the Arm_input_section object corresponding to the SHNDX-th input // section of RELOBJ. Arm_input_section* find_arm_input_section(Relobj* relobj, unsigned int shndx) const; // Make a new Stub_table Stub_table* new_stub_table(Arm_input_section*); // Scan a section for stub generation. void scan_section_for_stubs(const Relocate_info<32, big_endian>*, unsigned int, const unsigned char*, size_t, Output_section*, bool, const unsigned char*, Arm_address, section_size_type); // Relocate a stub. void relocate_stub(Reloc_stub*, const Relocate_info<32, big_endian>*, Output_section*, unsigned char*, Arm_address, section_size_type); // Get the default ARM target. static Target_arm* default_target() { gold_assert(parameters->target().machine_code() == elfcpp::EM_ARM && parameters->target().is_big_endian() == big_endian); return static_cast*>( parameters->sized_target<32, big_endian>()); } // Whether relocation type uses LSB to distinguish THUMB addresses. static bool reloc_uses_thumb_bit(unsigned int r_type); protected: // Make an ELF object. Object* do_make_elf_object(const std::string&, Input_file*, off_t, const elfcpp::Ehdr<32, big_endian>& ehdr); Object* do_make_elf_object(const std::string&, Input_file*, off_t, const elfcpp::Ehdr<32, !big_endian>&) { gold_unreachable(); } Object* do_make_elf_object(const std::string&, Input_file*, off_t, const elfcpp::Ehdr<64, false>&) { gold_unreachable(); } Object* do_make_elf_object(const std::string&, Input_file*, off_t, const elfcpp::Ehdr<64, true>&) { gold_unreachable(); } // Make an output section. Output_section* do_make_output_section(const char* name, elfcpp::Elf_Word type, elfcpp::Elf_Xword flags) { return new Arm_output_section(name, type, flags); } void do_adjust_elf_header(unsigned char* view, int len) const; // We only need to generate stubs, and hence perform relaxation if we are // not doing relocatable linking. bool do_may_relax() const { return !parameters->options().relocatable(); } bool do_relax(int, const Input_objects*, Symbol_table*, Layout*); private: // The class which scans relocations. class Scan { public: Scan() : issued_non_pic_error_(false) { } inline void local(Symbol_table* symtab, Layout* layout, Target_arm* target, Sized_relobj<32, big_endian>* object, unsigned int data_shndx, Output_section* output_section, const elfcpp::Rel<32, big_endian>& reloc, unsigned int r_type, const elfcpp::Sym<32, big_endian>& lsym); inline void global(Symbol_table* symtab, Layout* layout, Target_arm* target, Sized_relobj<32, big_endian>* object, unsigned int data_shndx, Output_section* output_section, const elfcpp::Rel<32, big_endian>& reloc, unsigned int r_type, Symbol* gsym); private: static void unsupported_reloc_local(Sized_relobj<32, big_endian>*, unsigned int r_type); static void unsupported_reloc_global(Sized_relobj<32, big_endian>*, unsigned int r_type, Symbol*); void check_non_pic(Relobj*, unsigned int r_type); // Almost identical to Symbol::needs_plt_entry except that it also // handles STT_ARM_TFUNC. static bool symbol_needs_plt_entry(const Symbol* sym) { // An undefined symbol from an executable does not need a PLT entry. if (sym->is_undefined() && !parameters->options().shared()) return false; return (!parameters->doing_static_link() && (sym->type() == elfcpp::STT_FUNC || sym->type() == elfcpp::STT_ARM_TFUNC) && (sym->is_from_dynobj() || sym->is_undefined() || sym->is_preemptible())); } // Whether we have issued an error about a non-PIC compilation. bool issued_non_pic_error_; }; // The class which implements relocation. class Relocate { public: Relocate() { } ~Relocate() { } // Return whether the static relocation needs to be applied. inline bool should_apply_static_reloc(const Sized_symbol<32>* gsym, int ref_flags, bool is_32bit, Output_section* output_section); // Do a relocation. Return false if the caller should not issue // any warnings about this relocation. inline bool relocate(const Relocate_info<32, big_endian>*, Target_arm*, Output_section*, size_t relnum, const elfcpp::Rel<32, big_endian>&, unsigned int r_type, const Sized_symbol<32>*, const Symbol_value<32>*, unsigned char*, Arm_address, section_size_type); // Return whether we want to pass flag NON_PIC_REF for this // reloc. static inline bool reloc_is_non_pic (unsigned int r_type) { switch (r_type) { case elfcpp::R_ARM_REL32: case elfcpp::R_ARM_THM_CALL: case elfcpp::R_ARM_CALL: case elfcpp::R_ARM_JUMP24: case elfcpp::R_ARM_PREL31: case elfcpp::R_ARM_THM_ABS5: case elfcpp::R_ARM_ABS8: case elfcpp::R_ARM_ABS12: case elfcpp::R_ARM_ABS16: case elfcpp::R_ARM_BASE_ABS: return true; default: return false; } } }; // A class which returns the size required for a relocation type, // used while scanning relocs during a relocatable link. class Relocatable_size_for_reloc { public: unsigned int get_size_for_reloc(unsigned int, Relobj*); }; // Get the GOT section, creating it if necessary. Output_data_got<32, big_endian>* got_section(Symbol_table*, Layout*); // Get the GOT PLT section. Output_data_space* got_plt_section() const { gold_assert(this->got_plt_ != NULL); return this->got_plt_; } // Create a PLT entry for a global symbol. void make_plt_entry(Symbol_table*, Layout*, Symbol*); // Get the PLT section. const Output_data_plt_arm* plt_section() const { gold_assert(this->plt_ != NULL); return this->plt_; } // Get the dynamic reloc section, creating it if necessary. Reloc_section* rel_dyn_section(Layout*); // Return true if the symbol may need a COPY relocation. // References from an executable object to non-function symbols // defined in a dynamic object may need a COPY relocation. bool may_need_copy_reloc(Symbol* gsym) { return (gsym->type() != elfcpp::STT_ARM_TFUNC && gsym->may_need_copy_reloc()); } // Add a potential copy relocation. void copy_reloc(Symbol_table* symtab, Layout* layout, Sized_relobj<32, big_endian>* object, unsigned int shndx, Output_section* output_section, Symbol* sym, const elfcpp::Rel<32, big_endian>& reloc) { this->copy_relocs_.copy_reloc(symtab, layout, symtab->get_sized_symbol<32>(sym), object, shndx, output_section, reloc, this->rel_dyn_section(layout)); } // Whether two EABI versions are compatible. static bool are_eabi_versions_compatible(elfcpp::Elf_Word v1, elfcpp::Elf_Word v2); // Merge processor-specific flags from input object and those in the ELF // header of the output. void merge_processor_specific_flags(const std::string&, elfcpp::Elf_Word); // // Methods to support stub-generations. // // Group input sections for stub generation. void group_sections(Layout*, section_size_type, bool); // Scan a relocation for stub generation. void scan_reloc_for_stub(const Relocate_info<32, big_endian>*, unsigned int, const Sized_symbol<32>*, unsigned int, const Symbol_value<32>*, elfcpp::Elf_types<32>::Elf_Swxword, Arm_address); // Scan a relocation section for stub. template void scan_reloc_section_for_stubs( const Relocate_info<32, big_endian>* relinfo, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, bool needs_special_offset_handling, const unsigned char* view, elfcpp::Elf_types<32>::Elf_Addr view_address, section_size_type); // Information about this specific target which we pass to the // general Target structure. static const Target::Target_info arm_info; // The types of GOT entries needed for this platform. enum Got_type { GOT_TYPE_STANDARD = 0 // GOT entry for a regular symbol }; typedef typename std::vector*> Stub_table_list; // Map input section to Arm_input_section. typedef Unordered_map*, Input_section_specifier::hash, Input_section_specifier::equal_to> Arm_input_section_map; // The GOT section. Output_data_got<32, big_endian>* got_; // The PLT section. Output_data_plt_arm* plt_; // The GOT PLT section. Output_data_space* got_plt_; // The dynamic reloc section. Reloc_section* rel_dyn_; // Relocs saved to avoid a COPY reloc. Copy_relocs copy_relocs_; // Space for variables copied with a COPY reloc. Output_data_space* dynbss_; // Vector of Stub_tables created. Stub_table_list stub_tables_; // Stub factory. const Stub_factory &stub_factory_; // Whether we can use BLX. bool may_use_blx_; // Whether we force PIC branch veneers. bool should_force_pic_veneer_; // Map for locating Arm_input_sections. Arm_input_section_map arm_input_section_map_; }; template const Target::Target_info Target_arm::arm_info = { 32, // size big_endian, // is_big_endian elfcpp::EM_ARM, // machine_code false, // has_make_symbol false, // has_resolve false, // has_code_fill true, // is_default_stack_executable '\0', // wrap_char "/usr/lib/libc.so.1", // dynamic_linker 0x8000, // default_text_segment_address 0x1000, // abi_pagesize (overridable by -z max-page-size) 0x1000, // common_pagesize (overridable by -z common-page-size) elfcpp::SHN_UNDEF, // small_common_shndx elfcpp::SHN_UNDEF, // large_common_shndx 0, // small_common_section_flags 0 // large_common_section_flags }; // Arm relocate functions class // template class Arm_relocate_functions : public Relocate_functions<32, big_endian> { public: typedef enum { STATUS_OKAY, // No error during relocation. STATUS_OVERFLOW, // Relocation oveflow. STATUS_BAD_RELOC // Relocation cannot be applied. } Status; private: typedef Relocate_functions<32, big_endian> Base; typedef Arm_relocate_functions This; // Encoding of imm16 argument for movt and movw ARM instructions // from ARM ARM: // // imm16 := imm4 | imm12 // // f e d c b a 9 8 7 6 5 4 3 2 1 0 f e d c b a 9 8 7 6 5 4 3 2 1 0 // +-------+---------------+-------+-------+-----------------------+ // | | |imm4 | |imm12 | // +-------+---------------+-------+-------+-----------------------+ // Extract the relocation addend from VAL based on the ARM // instruction encoding described above. static inline typename elfcpp::Swap<32, big_endian>::Valtype extract_arm_movw_movt_addend( typename elfcpp::Swap<32, big_endian>::Valtype val) { // According to the Elf ABI for ARM Architecture the immediate // field is sign-extended to form the addend. return utils::sign_extend<16>(((val >> 4) & 0xf000) | (val & 0xfff)); } // Insert X into VAL based on the ARM instruction encoding described // above. static inline typename elfcpp::Swap<32, big_endian>::Valtype insert_val_arm_movw_movt( typename elfcpp::Swap<32, big_endian>::Valtype val, typename elfcpp::Swap<32, big_endian>::Valtype x) { val &= 0xfff0f000; val |= x & 0x0fff; val |= (x & 0xf000) << 4; return val; } // Encoding of imm16 argument for movt and movw Thumb2 instructions // from ARM ARM: // // imm16 := imm4 | i | imm3 | imm8 // // f e d c b a 9 8 7 6 5 4 3 2 1 0 f e d c b a 9 8 7 6 5 4 3 2 1 0 // +---------+-+-----------+-------++-+-----+-------+---------------+ // | |i| |imm4 || |imm3 | |imm8 | // +---------+-+-----------+-------++-+-----+-------+---------------+ // Extract the relocation addend from VAL based on the Thumb2 // instruction encoding described above. static inline typename elfcpp::Swap<32, big_endian>::Valtype extract_thumb_movw_movt_addend( typename elfcpp::Swap<32, big_endian>::Valtype val) { // According to the Elf ABI for ARM Architecture the immediate // field is sign-extended to form the addend. return utils::sign_extend<16>(((val >> 4) & 0xf000) | ((val >> 15) & 0x0800) | ((val >> 4) & 0x0700) | (val & 0x00ff)); } // Insert X into VAL based on the Thumb2 instruction encoding // described above. static inline typename elfcpp::Swap<32, big_endian>::Valtype insert_val_thumb_movw_movt( typename elfcpp::Swap<32, big_endian>::Valtype val, typename elfcpp::Swap<32, big_endian>::Valtype x) { val &= 0xfbf08f00; val |= (x & 0xf000) << 4; val |= (x & 0x0800) << 15; val |= (x & 0x0700) << 4; val |= (x & 0x00ff); return val; } // Handle ARM long branches. static typename This::Status arm_branch_common(unsigned int, const Relocate_info<32, big_endian>*, unsigned char *, const Sized_symbol<32>*, const Arm_relobj*, unsigned int, const Symbol_value<32>*, Arm_address, Arm_address, bool); public: // R_ARM_ABS8: S + A static inline typename This::Status abs8(unsigned char *view, const Sized_relobj<32, big_endian>* object, const Symbol_value<32>* psymval) { typedef typename elfcpp::Swap<8, big_endian>::Valtype Valtype; typedef typename elfcpp::Swap<32, big_endian>::Valtype Reltype; Valtype* wv = reinterpret_cast(view); Valtype val = elfcpp::Swap<8, big_endian>::readval(wv); Reltype addend = utils::sign_extend<8>(val); Reltype x = psymval->value(object, addend); val = utils::bit_select(val, x, 0xffU); elfcpp::Swap<8, big_endian>::writeval(wv, val); return (utils::has_signed_unsigned_overflow<8>(x) ? This::STATUS_OVERFLOW : This::STATUS_OKAY); } // R_ARM_THM_ABS5: S + A static inline typename This::Status thm_abs5(unsigned char *view, const Sized_relobj<32, big_endian>* object, const Symbol_value<32>* psymval) { typedef typename elfcpp::Swap<16, big_endian>::Valtype Valtype; typedef typename elfcpp::Swap<32, big_endian>::Valtype Reltype; Valtype* wv = reinterpret_cast(view); Valtype val = elfcpp::Swap<16, big_endian>::readval(wv); Reltype addend = (val & 0x7e0U) >> 6; Reltype x = psymval->value(object, addend); val = utils::bit_select(val, x << 6, 0x7e0U); elfcpp::Swap<16, big_endian>::writeval(wv, val); return (utils::has_overflow<5>(x) ? This::STATUS_OVERFLOW : This::STATUS_OKAY); } // R_ARM_ABS12: S + A static inline typename This::Status abs12(unsigned char *view, const Sized_relobj<32, big_endian>* object, const Symbol_value<32>* psymval) { typedef typename elfcpp::Swap<32, big_endian>::Valtype Valtype; typedef typename elfcpp::Swap<32, big_endian>::Valtype Reltype; Valtype* wv = reinterpret_cast(view); Valtype val = elfcpp::Swap<32, big_endian>::readval(wv); Reltype addend = val & 0x0fffU; Reltype x = psymval->value(object, addend); val = utils::bit_select(val, x, 0x0fffU); elfcpp::Swap<32, big_endian>::writeval(wv, val); return (utils::has_overflow<12>(x) ? This::STATUS_OVERFLOW : This::STATUS_OKAY); } // R_ARM_ABS16: S + A static inline typename This::Status abs16(unsigned char *view, const Sized_relobj<32, big_endian>* object, const Symbol_value<32>* psymval) { typedef typename elfcpp::Swap<16, big_endian>::Valtype Valtype; typedef typename elfcpp::Swap<32, big_endian>::Valtype Reltype; Valtype* wv = reinterpret_cast(view); Valtype val = elfcpp::Swap<16, big_endian>::readval(wv); Reltype addend = utils::sign_extend<16>(val); Reltype x = psymval->value(object, addend); val = utils::bit_select(val, x, 0xffffU); elfcpp::Swap<16, big_endian>::writeval(wv, val); return (utils::has_signed_unsigned_overflow<16>(x) ? This::STATUS_OVERFLOW : This::STATUS_OKAY); } // R_ARM_ABS32: (S + A) | T static inline typename This::Status abs32(unsigned char *view, const Sized_relobj<32, big_endian>* object, const Symbol_value<32>* psymval, Arm_address thumb_bit) { typedef typename elfcpp::Swap<32, big_endian>::Valtype Valtype; Valtype* wv = reinterpret_cast(view); Valtype addend = elfcpp::Swap<32, big_endian>::readval(wv); Valtype x = psymval->value(object, addend) | thumb_bit; elfcpp::Swap<32, big_endian>::writeval(wv, x); return This::STATUS_OKAY; } // R_ARM_REL32: (S + A) | T - P static inline typename This::Status rel32(unsigned char *view, const Sized_relobj<32, big_endian>* object, const Symbol_value<32>* psymval, Arm_address address, Arm_address thumb_bit) { typedef typename elfcpp::Swap<32, big_endian>::Valtype Valtype; Valtype* wv = reinterpret_cast(view); Valtype addend = elfcpp::Swap<32, big_endian>::readval(wv); Valtype x = (psymval->value(object, addend) | thumb_bit) - address; elfcpp::Swap<32, big_endian>::writeval(wv, x); return This::STATUS_OKAY; } // R_ARM_THM_CALL: (S + A) | T - P static inline typename This::Status thm_call(unsigned char *view, const Sized_relobj<32, big_endian>* object, const Symbol_value<32>* psymval, Arm_address address, Arm_address thumb_bit) { // A thumb call consists of two instructions. typedef typename elfcpp::Swap<16, big_endian>::Valtype Valtype; typedef typename elfcpp::Swap<32, big_endian>::Valtype Reltype; Valtype* wv = reinterpret_cast(view); Valtype hi = elfcpp::Swap<16, big_endian>::readval(wv); Valtype lo = elfcpp::Swap<16, big_endian>::readval(wv + 1); // Must be a BL instruction. lo == 11111xxxxxxxxxxx. gold_assert((lo & 0xf800) == 0xf800); Reltype addend = utils::sign_extend<23>(((hi & 0x7ff) << 12) | ((lo & 0x7ff) << 1)); Reltype x = (psymval->value(object, addend) | thumb_bit) - address; // If target has no thumb bit set, we need to either turn the BL // into a BLX (for ARMv5 or above) or generate a stub. if ((x & 1) == 0) { // This only works for ARMv5 and above with interworking enabled. lo &= 0xefff; } hi = utils::bit_select(hi, (x >> 12), 0x7ffU); lo = utils::bit_select(lo, (x >> 1), 0x7ffU); elfcpp::Swap<16, big_endian>::writeval(wv, hi); elfcpp::Swap<16, big_endian>::writeval(wv + 1, lo); return (utils::has_overflow<23>(x) ? This::STATUS_OVERFLOW : This::STATUS_OKAY); } // R_ARM_BASE_PREL: B(S) + A - P static inline typename This::Status base_prel(unsigned char* view, Arm_address origin, Arm_address address) { Base::rel32(view, origin - address); return STATUS_OKAY; } // R_ARM_BASE_ABS: B(S) + A static inline typename This::Status base_abs(unsigned char* view, Arm_address origin) { Base::rel32(view, origin); return STATUS_OKAY; } // R_ARM_GOT_BREL: GOT(S) + A - GOT_ORG static inline typename This::Status got_brel(unsigned char* view, typename elfcpp::Swap<32, big_endian>::Valtype got_offset) { Base::rel32(view, got_offset); return This::STATUS_OKAY; } // R_ARM_GOT_PREL: GOT(S) + A – P static inline typename This::Status got_prel(unsigned char* view, typename elfcpp::Swap<32, big_endian>::Valtype got_offset, Arm_address address) { Base::rel32(view, got_offset - address); return This::STATUS_OKAY; } // R_ARM_PLT32: (S + A) | T - P static inline typename This::Status plt32(const Relocate_info<32, big_endian>* relinfo, unsigned char *view, const Sized_symbol<32>* gsym, const Arm_relobj* object, unsigned int r_sym, const Symbol_value<32>* psymval, Arm_address address, Arm_address thumb_bit, bool is_weakly_undefined_without_plt) { return arm_branch_common(elfcpp::R_ARM_PLT32, relinfo, view, gsym, object, r_sym, psymval, address, thumb_bit, is_weakly_undefined_without_plt); } // R_ARM_XPC25: (S + A) | T - P static inline typename This::Status xpc25(const Relocate_info<32, big_endian>* relinfo, unsigned char *view, const Sized_symbol<32>* gsym, const Arm_relobj* object, unsigned int r_sym, const Symbol_value<32>* psymval, Arm_address address, Arm_address thumb_bit, bool is_weakly_undefined_without_plt) { return arm_branch_common(elfcpp::R_ARM_XPC25, relinfo, view, gsym, object, r_sym, psymval, address, thumb_bit, is_weakly_undefined_without_plt); } // R_ARM_CALL: (S + A) | T - P static inline typename This::Status call(const Relocate_info<32, big_endian>* relinfo, unsigned char *view, const Sized_symbol<32>* gsym, const Arm_relobj* object, unsigned int r_sym, const Symbol_value<32>* psymval, Arm_address address, Arm_address thumb_bit, bool is_weakly_undefined_without_plt) { return arm_branch_common(elfcpp::R_ARM_CALL, relinfo, view, gsym, object, r_sym, psymval, address, thumb_bit, is_weakly_undefined_without_plt); } // R_ARM_JUMP24: (S + A) | T - P static inline typename This::Status jump24(const Relocate_info<32, big_endian>* relinfo, unsigned char *view, const Sized_symbol<32>* gsym, const Arm_relobj* object, unsigned int r_sym, const Symbol_value<32>* psymval, Arm_address address, Arm_address thumb_bit, bool is_weakly_undefined_without_plt) { return arm_branch_common(elfcpp::R_ARM_JUMP24, relinfo, view, gsym, object, r_sym, psymval, address, thumb_bit, is_weakly_undefined_without_plt); } // R_ARM_PREL: (S + A) | T - P static inline typename This::Status prel31(unsigned char *view, const Sized_relobj<32, big_endian>* object, const Symbol_value<32>* psymval, Arm_address address, Arm_address thumb_bit) { typedef typename elfcpp::Swap<32, big_endian>::Valtype Valtype; Valtype* wv = reinterpret_cast(view); Valtype val = elfcpp::Swap<32, big_endian>::readval(wv); Valtype addend = utils::sign_extend<31>(val); Valtype x = (psymval->value(object, addend) | thumb_bit) - address; val = utils::bit_select(val, x, 0x7fffffffU); elfcpp::Swap<32, big_endian>::writeval(wv, val); return (utils::has_overflow<31>(x) ? This::STATUS_OVERFLOW : This::STATUS_OKAY); } // R_ARM_MOVW_ABS_NC: (S + A) | T static inline typename This::Status movw_abs_nc(unsigned char *view, const Sized_relobj<32, big_endian>* object, const Symbol_value<32>* psymval, Arm_address thumb_bit) { typedef typename elfcpp::Swap<32, big_endian>::Valtype Valtype; Valtype* wv = reinterpret_cast(view); Valtype val = elfcpp::Swap<32, big_endian>::readval(wv); Valtype addend = This::extract_arm_movw_movt_addend(val); Valtype x = psymval->value(object, addend) | thumb_bit; val = This::insert_val_arm_movw_movt(val, x); elfcpp::Swap<32, big_endian>::writeval(wv, val); return This::STATUS_OKAY; } // R_ARM_MOVT_ABS: S + A static inline typename This::Status movt_abs(unsigned char *view, const Sized_relobj<32, big_endian>* object, const Symbol_value<32>* psymval) { typedef typename elfcpp::Swap<32, big_endian>::Valtype Valtype; Valtype* wv = reinterpret_cast(view); Valtype val = elfcpp::Swap<32, big_endian>::readval(wv); Valtype addend = This::extract_arm_movw_movt_addend(val); Valtype x = psymval->value(object, addend) >> 16; val = This::insert_val_arm_movw_movt(val, x); elfcpp::Swap<32, big_endian>::writeval(wv, val); return This::STATUS_OKAY; } // R_ARM_THM_MOVW_ABS_NC: S + A | T static inline typename This::Status thm_movw_abs_nc(unsigned char *view, const Sized_relobj<32, big_endian>* object, const Symbol_value<32>* psymval, Arm_address thumb_bit) { typedef typename elfcpp::Swap<16, big_endian>::Valtype Valtype; typedef typename elfcpp::Swap<32, big_endian>::Valtype Reltype; Valtype* wv = reinterpret_cast(view); Reltype val = ((elfcpp::Swap<16, big_endian>::readval(wv) << 16) | elfcpp::Swap<16, big_endian>::readval(wv + 1)); Reltype addend = extract_thumb_movw_movt_addend(val); Reltype x = psymval->value(object, addend) | thumb_bit; val = This::insert_val_thumb_movw_movt(val, x); elfcpp::Swap<16, big_endian>::writeval(wv, val >> 16); elfcpp::Swap<16, big_endian>::writeval(wv + 1, val & 0xffff); return This::STATUS_OKAY; } // R_ARM_THM_MOVT_ABS: S + A static inline typename This::Status thm_movt_abs(unsigned char *view, const Sized_relobj<32, big_endian>* object, const Symbol_value<32>* psymval) { typedef typename elfcpp::Swap<16, big_endian>::Valtype Valtype; typedef typename elfcpp::Swap<32, big_endian>::Valtype Reltype; Valtype* wv = reinterpret_cast(view); Reltype val = ((elfcpp::Swap<16, big_endian>::readval(wv) << 16) | elfcpp::Swap<16, big_endian>::readval(wv + 1)); Reltype addend = This::extract_thumb_movw_movt_addend(val); Reltype x = psymval->value(object, addend) >> 16; val = This::insert_val_thumb_movw_movt(val, x); elfcpp::Swap<16, big_endian>::writeval(wv, val >> 16); elfcpp::Swap<16, big_endian>::writeval(wv + 1, val & 0xffff); return This::STATUS_OKAY; } // R_ARM_MOVW_PREL_NC: (S + A) | T - P static inline typename This::Status movw_prel_nc(unsigned char *view, const Sized_relobj<32, big_endian>* object, const Symbol_value<32>* psymval, Arm_address address, Arm_address thumb_bit) { typedef typename elfcpp::Swap<32, big_endian>::Valtype Valtype; Valtype* wv = reinterpret_cast(view); Valtype val = elfcpp::Swap<32, big_endian>::readval(wv); Valtype addend = This::extract_arm_movw_movt_addend(val); Valtype x = (psymval->value(object, addend) | thumb_bit) - address; val = This::insert_val_arm_movw_movt(val, x); elfcpp::Swap<32, big_endian>::writeval(wv, val); return This::STATUS_OKAY; } // R_ARM_MOVT_PREL: S + A - P static inline typename This::Status movt_prel(unsigned char *view, const Sized_relobj<32, big_endian>* object, const Symbol_value<32>* psymval, Arm_address address) { typedef typename elfcpp::Swap<32, big_endian>::Valtype Valtype; Valtype* wv = reinterpret_cast(view); Valtype val = elfcpp::Swap<32, big_endian>::readval(wv); Valtype addend = This::extract_arm_movw_movt_addend(val); Valtype x = (psymval->value(object, addend) - address) >> 16; val = This::insert_val_arm_movw_movt(val, x); elfcpp::Swap<32, big_endian>::writeval(wv, val); return This::STATUS_OKAY; } // R_ARM_THM_MOVW_PREL_NC: (S + A) | T - P static inline typename This::Status thm_movw_prel_nc(unsigned char *view, const Sized_relobj<32, big_endian>* object, const Symbol_value<32>* psymval, Arm_address address, Arm_address thumb_bit) { typedef typename elfcpp::Swap<16, big_endian>::Valtype Valtype; typedef typename elfcpp::Swap<32, big_endian>::Valtype Reltype; Valtype* wv = reinterpret_cast(view); Reltype val = (elfcpp::Swap<16, big_endian>::readval(wv) << 16) | elfcpp::Swap<16, big_endian>::readval(wv + 1); Reltype addend = This::extract_thumb_movw_movt_addend(val); Reltype x = (psymval->value(object, addend) | thumb_bit) - address; val = This::insert_val_thumb_movw_movt(val, x); elfcpp::Swap<16, big_endian>::writeval(wv, val >> 16); elfcpp::Swap<16, big_endian>::writeval(wv + 1, val & 0xffff); return This::STATUS_OKAY; } // R_ARM_THM_MOVT_PREL: S + A - P static inline typename This::Status thm_movt_prel(unsigned char *view, const Sized_relobj<32, big_endian>* object, const Symbol_value<32>* psymval, Arm_address address) { typedef typename elfcpp::Swap<16, big_endian>::Valtype Valtype; typedef typename elfcpp::Swap<32, big_endian>::Valtype Reltype; Valtype* wv = reinterpret_cast(view); Reltype val = (elfcpp::Swap<16, big_endian>::readval(wv) << 16) | elfcpp::Swap<16, big_endian>::readval(wv + 1); Reltype addend = This::extract_thumb_movw_movt_addend(val); Reltype x = (psymval->value(object, addend) - address) >> 16; val = This::insert_val_thumb_movw_movt(val, x); elfcpp::Swap<16, big_endian>::writeval(wv, val >> 16); elfcpp::Swap<16, big_endian>::writeval(wv + 1, val & 0xffff); return This::STATUS_OKAY; } }; // Relocate ARM long branches. This handles relocation types // R_ARM_CALL, R_ARM_JUMP24, R_ARM_PLT32 and R_ARM_XPC25. // If IS_WEAK_UNDEFINED_WITH_PLT is true. The target symbol is weakly // undefined and we do not use PLT in this relocation. In such a case, // the branch is converted into an NOP. template typename Arm_relocate_functions::Status Arm_relocate_functions::arm_branch_common( unsigned int r_type, const Relocate_info<32, big_endian>* relinfo, unsigned char *view, const Sized_symbol<32>* gsym, const Arm_relobj* object, unsigned int r_sym, const Symbol_value<32>* psymval, Arm_address address, Arm_address thumb_bit, bool is_weakly_undefined_without_plt) { typedef typename elfcpp::Swap<32, big_endian>::Valtype Valtype; Valtype* wv = reinterpret_cast(view); Valtype val = elfcpp::Swap<32, big_endian>::readval(wv); bool insn_is_b = (((val >> 28) & 0xf) <= 0xe) && ((val & 0x0f000000UL) == 0x0a000000UL); bool insn_is_uncond_bl = (val & 0xff000000UL) == 0xeb000000UL; bool insn_is_cond_bl = (((val >> 28) & 0xf) < 0xe) && ((val & 0x0f000000UL) == 0x0b000000UL); bool insn_is_blx = (val & 0xfe000000UL) == 0xfa000000UL; bool insn_is_any_branch = (val & 0x0e000000UL) == 0x0a000000UL; // Check that the instruction is valid. if (r_type == elfcpp::R_ARM_CALL) { if (!insn_is_uncond_bl && !insn_is_blx) return This::STATUS_BAD_RELOC; } else if (r_type == elfcpp::R_ARM_JUMP24) { if (!insn_is_b && !insn_is_cond_bl) return This::STATUS_BAD_RELOC; } else if (r_type == elfcpp::R_ARM_PLT32) { if (!insn_is_any_branch) return This::STATUS_BAD_RELOC; } else if (r_type == elfcpp::R_ARM_XPC25) { // FIXME: AAELF document IH0044C does not say much about it other // than it being obsolete. if (!insn_is_any_branch) return This::STATUS_BAD_RELOC; } else gold_unreachable(); // A branch to an undefined weak symbol is turned into a jump to // the next instruction unless a PLT entry will be created. // Do the same for local undefined symbols. // The jump to the next instruction is optimized as a NOP depending // on the architecture. const Target_arm* arm_target = Target_arm::default_target(); if (is_weakly_undefined_without_plt) { Valtype cond = val & 0xf0000000U; if (arm_target->may_use_arm_nop()) val = cond | 0x0320f000; else val = cond | 0x01a00000; // Using pre-UAL nop: mov r0, r0. elfcpp::Swap<32, big_endian>::writeval(wv, val); return This::STATUS_OKAY; } Valtype addend = utils::sign_extend<26>(val << 2); Valtype branch_target = psymval->value(object, addend); int32_t branch_offset = branch_target - address; // We need a stub if the branch offset is too large or if we need // to switch mode. bool may_use_blx = arm_target->may_use_blx(); Reloc_stub* stub = NULL; if ((branch_offset > ARM_MAX_FWD_BRANCH_OFFSET) || (branch_offset < ARM_MAX_BWD_BRANCH_OFFSET) || ((thumb_bit != 0) && !(may_use_blx && r_type == elfcpp::R_ARM_CALL))) { Stub_type stub_type = Reloc_stub::stub_type_for_reloc(r_type, address, branch_target, (thumb_bit != 0)); if (stub_type != arm_stub_none) { Stub_table* stub_table = object->stub_table(relinfo->data_shndx); gold_assert(stub_table != NULL); Reloc_stub::Key stub_key(stub_type, gsym, object, r_sym, addend); stub = stub_table->find_reloc_stub(stub_key); gold_assert(stub != NULL); thumb_bit = stub->stub_template()->entry_in_thumb_mode() ? 1 : 0; branch_target = stub_table->address() + stub->offset() + addend; branch_offset = branch_target - address; gold_assert((branch_offset <= ARM_MAX_FWD_BRANCH_OFFSET) && (branch_offset >= ARM_MAX_BWD_BRANCH_OFFSET)); } } // At this point, if we still need to switch mode, the instruction // must either be a BLX or a BL that can be converted to a BLX. if (thumb_bit != 0) { // Turn BL to BLX. gold_assert(may_use_blx && r_type == elfcpp::R_ARM_CALL); val = (val & 0xffffff) | 0xfa000000 | ((branch_offset & 2) << 23); } val = utils::bit_select(val, (branch_offset >> 2), 0xffffffUL); elfcpp::Swap<32, big_endian>::writeval(wv, val); return (utils::has_overflow<26>(branch_offset) ? This::STATUS_OVERFLOW : This::STATUS_OKAY); } // Get the GOT section, creating it if necessary. template Output_data_got<32, big_endian>* Target_arm::got_section(Symbol_table* symtab, Layout* layout) { if (this->got_ == NULL) { gold_assert(symtab != NULL && layout != NULL); this->got_ = new Output_data_got<32, big_endian>(); Output_section* os; os = layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS, (elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE), this->got_, false); os->set_is_relro(); // The old GNU linker creates a .got.plt section. We just // create another set of data in the .got section. Note that we // always create a PLT if we create a GOT, although the PLT // might be empty. this->got_plt_ = new Output_data_space(4, "** GOT PLT"); os = layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS, (elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE), this->got_plt_, false); os->set_is_relro(); // The first three entries are reserved. this->got_plt_->set_current_data_size(3 * 4); // Define _GLOBAL_OFFSET_TABLE_ at the start of the PLT. symtab->define_in_output_data("_GLOBAL_OFFSET_TABLE_", NULL, this->got_plt_, 0, 0, elfcpp::STT_OBJECT, elfcpp::STB_LOCAL, elfcpp::STV_HIDDEN, 0, false, false); } return this->got_; } // Get the dynamic reloc section, creating it if necessary. template typename Target_arm::Reloc_section* Target_arm::rel_dyn_section(Layout* layout) { if (this->rel_dyn_ == NULL) { gold_assert(layout != NULL); this->rel_dyn_ = new Reloc_section(parameters->options().combreloc()); layout->add_output_section_data(".rel.dyn", elfcpp::SHT_REL, elfcpp::SHF_ALLOC, this->rel_dyn_, true); } return this->rel_dyn_; } // Insn_template methods. // Return byte size of an instruction template. size_t Insn_template::size() const { switch (this->type()) { case THUMB16_TYPE: return 2; case ARM_TYPE: case THUMB32_TYPE: case DATA_TYPE: return 4; default: gold_unreachable(); } } // Return alignment of an instruction template. unsigned Insn_template::alignment() const { switch (this->type()) { case THUMB16_TYPE: case THUMB32_TYPE: return 2; case ARM_TYPE: case DATA_TYPE: return 4; default: gold_unreachable(); } } // Stub_template methods. Stub_template::Stub_template( Stub_type type, const Insn_template* insns, size_t insn_count) : type_(type), insns_(insns), insn_count_(insn_count), alignment_(1), entry_in_thumb_mode_(false), relocs_() { off_t offset = 0; // Compute byte size and alignment of stub template. for (size_t i = 0; i < insn_count; i++) { unsigned insn_alignment = insns[i].alignment(); size_t insn_size = insns[i].size(); gold_assert((offset & (insn_alignment - 1)) == 0); this->alignment_ = std::max(this->alignment_, insn_alignment); switch (insns[i].type()) { case Insn_template::THUMB16_TYPE: if (i == 0) this->entry_in_thumb_mode_ = true; break; case Insn_template::THUMB32_TYPE: if (insns[i].r_type() != elfcpp::R_ARM_NONE) this->relocs_.push_back(Reloc(i, offset)); if (i == 0) this->entry_in_thumb_mode_ = true; break; case Insn_template::ARM_TYPE: // Handle cases where the target is encoded within the // instruction. if (insns[i].r_type() == elfcpp::R_ARM_JUMP24) this->relocs_.push_back(Reloc(i, offset)); break; case Insn_template::DATA_TYPE: // Entry point cannot be data. gold_assert(i != 0); this->relocs_.push_back(Reloc(i, offset)); break; default: gold_unreachable(); } offset += insn_size; } this->size_ = offset; } // Reloc_stub::Key methods. // Dump a Key as a string for debugging. std::string Reloc_stub::Key::name() const { if (this->r_sym_ == invalid_index) { // Global symbol key name // ::. const std::string sym_name = this->u_.symbol->name(); // We need to print two hex number and two colons. So just add 100 bytes // to the symbol name size. size_t len = sym_name.size() + 100; char* buffer = new char[len]; int c = snprintf(buffer, len, "%d:%s:%x", this->stub_type_, sym_name.c_str(), this->addend_); gold_assert(c > 0 && c < static_cast(len)); delete[] buffer; return std::string(buffer); } else { // local symbol key name // :