// reloc.h -- relocate input files for gold -*- C++ -*- // Copyright 2006, 2007 Free Software Foundation, Inc. // Written by Ian Lance Taylor . // This file is part of gold. // This program is free software; you can redistribute it and/or modify // it under the terms of the GNU 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. #ifndef GOLD_RELOC_H #define GOLD_RELOC_H #include #include #include "elfcpp.h" #include "workqueue.h" namespace gold { class General_options; class Object; class Relobj; class Read_relocs_data; class Symbol; class Layout; class Output_section; template class Sized_symbol; template class Sized_relobj; template class Symbol_value; template class Output_data_reloc; // A class to read the relocations for an object file, and then queue // up a task to see if they require any GOT/PLT/COPY relocations in // the symbol table. class Read_relocs : public Task { public: // SYMTAB_LOCK is used to lock the symbol table. BLOCKER should be // unblocked when the Scan_relocs task completes. Read_relocs(const General_options& options, Symbol_table* symtab, Layout* layout, Relobj* object, Task_token* symtab_lock, Task_token* blocker) : options_(options), symtab_(symtab), layout_(layout), object_(object), symtab_lock_(symtab_lock), blocker_(blocker) { } // The standard Task methods. Task_token* is_runnable(); void locks(Task_locker*); void run(Workqueue*); std::string get_name() const; private: const General_options& options_; Symbol_table* symtab_; Layout* layout_; Relobj* object_; Task_token* symtab_lock_; Task_token* blocker_; }; // Scan the relocations for an object to see if they require any // GOT/PLT/COPY relocations. class Scan_relocs : public Task { public: // SYMTAB_LOCK is used to lock the symbol table. BLOCKER should be // unblocked when the task completes. Scan_relocs(const General_options& options, Symbol_table* symtab, Layout* layout, Relobj* object, Read_relocs_data* rd, Task_token* symtab_lock, Task_token* blocker) : options_(options), symtab_(symtab), layout_(layout), object_(object), rd_(rd), symtab_lock_(symtab_lock), blocker_(blocker) { } // The standard Task methods. Task_token* is_runnable(); void locks(Task_locker*); void run(Workqueue*); std::string get_name() const; private: const General_options& options_; Symbol_table* symtab_; Layout* layout_; Relobj* object_; Read_relocs_data* rd_; Task_token* symtab_lock_; Task_token* blocker_; }; // A class to perform all the relocations for an object file. class Relocate_task : public Task { public: Relocate_task(const General_options& options, const Symbol_table* symtab, const Layout* layout, Relobj* object, Output_file* of, Task_token* input_sections_blocker, Task_token* output_sections_blocker, Task_token* final_blocker) : options_(options), symtab_(symtab), layout_(layout), object_(object), of_(of), input_sections_blocker_(input_sections_blocker), output_sections_blocker_(output_sections_blocker), final_blocker_(final_blocker) { } // The standard Task methods. Task_token* is_runnable(); void locks(Task_locker*); void run(Workqueue*); std::string get_name() const; private: const General_options& options_; const Symbol_table* symtab_; const Layout* layout_; Relobj* object_; Output_file* of_; Task_token* input_sections_blocker_; Task_token* output_sections_blocker_; Task_token* final_blocker_; }; // Standard relocation routines which are used on many targets. Here // SIZE and BIG_ENDIAN refer to the target, not the relocation type. template class Relocate_functions { private: // Do a simple relocation with the addend in the section contents. // VALSIZE is the size of the value. template static inline void rel(unsigned char* view, typename elfcpp::Swap::Valtype value) { typedef typename elfcpp::Swap::Valtype Valtype; Valtype* wv = reinterpret_cast(view); Valtype x = elfcpp::Swap::readval(wv); elfcpp::Swap::writeval(wv, x + value); } // Do a simple relocation using a Symbol_value with the addend in // the section contents. VALSIZE is the size of the value to // relocate. template static inline void rel(unsigned char* view, const Sized_relobj* object, const Symbol_value* psymval) { typedef typename elfcpp::Swap::Valtype Valtype; Valtype* wv = reinterpret_cast(view); Valtype x = elfcpp::Swap::readval(wv); x = psymval->value(object, x); elfcpp::Swap::writeval(wv, x); } // Do a simple relocation with the addend in the relocation. // VALSIZE is the size of the value. template static inline void rela(unsigned char* view, typename elfcpp::Swap::Valtype value, typename elfcpp::Swap::Valtype addend) { typedef typename elfcpp::Swap::Valtype Valtype; Valtype* wv = reinterpret_cast(view); elfcpp::Swap::writeval(wv, value + addend); } // Do a simple relocation using a symbol value with the addend in // the relocation. VALSIZE is the size of the value. template static inline void rela(unsigned char* view, const Sized_relobj* object, const Symbol_value* psymval, typename elfcpp::Swap::Valtype addend) { typedef typename elfcpp::Swap::Valtype Valtype; Valtype* wv = reinterpret_cast(view); Valtype x = psymval->value(object, addend); elfcpp::Swap::writeval(wv, x); } // Do a simple PC relative relocation with the addend in the section // contents. VALSIZE is the size of the value. template static inline void pcrel(unsigned char* view, typename elfcpp::Swap::Valtype value, typename elfcpp::Elf_types::Elf_Addr address) { typedef typename elfcpp::Swap::Valtype Valtype; Valtype* wv = reinterpret_cast(view); Valtype x = elfcpp::Swap::readval(wv); elfcpp::Swap::writeval(wv, x + value - address); } // Do a simple PC relative relocation with a Symbol_value with the // addend in the section contents. VALSIZE is the size of the // value. template static inline void pcrel(unsigned char* view, const Sized_relobj* object, const Symbol_value* psymval, typename elfcpp::Elf_types::Elf_Addr address) { typedef typename elfcpp::Swap::Valtype Valtype; Valtype* wv = reinterpret_cast(view); Valtype x = elfcpp::Swap::readval(wv); x = psymval->value(object, x); elfcpp::Swap::writeval(wv, x - address); } // Do a simple PC relative relocation with the addend in the // relocation. VALSIZE is the size of the value. template static inline void pcrela(unsigned char* view, typename elfcpp::Swap::Valtype value, typename elfcpp::Swap::Valtype addend, typename elfcpp::Elf_types::Elf_Addr address) { typedef typename elfcpp::Swap::Valtype Valtype; Valtype* wv = reinterpret_cast(view); elfcpp::Swap::writeval(wv, value + addend - address); } // Do a simple PC relative relocation with a Symbol_value with the // addend in the relocation. VALSIZE is the size of the value. template static inline void pcrela(unsigned char* view, const Sized_relobj* object, const Symbol_value* psymval, typename elfcpp::Swap::Valtype addend, typename elfcpp::Elf_types::Elf_Addr address) { typedef typename elfcpp::Swap::Valtype Valtype; Valtype* wv = reinterpret_cast(view); Valtype x = psymval->value(object, addend); elfcpp::Swap::writeval(wv, x - address); } typedef Relocate_functions This; public: // Do a simple 8-bit REL relocation with the addend in the section // contents. static inline void rel8(unsigned char* view, unsigned char value) { This::template rel<8>(view, value); } static inline void rel8(unsigned char* view, const Sized_relobj* object, const Symbol_value* psymval) { This::template rel<8>(view, object, psymval); } // Do an 8-bit RELA relocation with the addend in the relocation. static inline void rela8(unsigned char* view, unsigned char value, unsigned char addend) { This::template rela<8>(view, value, addend); } static inline void rela8(unsigned char* view, const Sized_relobj* object, const Symbol_value* psymval, unsigned char addend) { This::template rela<8>(view, object, psymval, addend); } // Do a simple 8-bit PC relative relocation with the addend in the // section contents. static inline void pcrel8(unsigned char* view, unsigned char value, typename elfcpp::Elf_types::Elf_Addr address) { This::template pcrel<8>(view, value, address); } static inline void pcrel8(unsigned char* view, const Sized_relobj* object, const Symbol_value* psymval, typename elfcpp::Elf_types::Elf_Addr address) { This::template pcrel<8>(view, object, psymval, address); } // Do a simple 8-bit PC relative RELA relocation with the addend in // the reloc. static inline void pcrela8(unsigned char* view, unsigned char value, unsigned char addend, typename elfcpp::Elf_types::Elf_Addr address) { This::template pcrela<8>(view, value, addend, address); } static inline void pcrela8(unsigned char* view, const Sized_relobj* object, const Symbol_value* psymval, unsigned char addend, typename elfcpp::Elf_types::Elf_Addr address) { This::template pcrela<8>(view, object, psymval, addend, address); } // Do a simple 16-bit REL relocation with the addend in the section // contents. static inline void rel16(unsigned char* view, elfcpp::Elf_Half value) { This::template rel<16>(view, value); } static inline void rel16(unsigned char* view, const Sized_relobj* object, const Symbol_value* psymval) { This::template rel<16>(view, object, psymval); } // Do an 16-bit RELA relocation with the addend in the relocation. static inline void rela16(unsigned char* view, elfcpp::Elf_Half value, elfcpp::Elf_Half addend) { This::template rela<16>(view, value, addend); } static inline void rela16(unsigned char* view, const Sized_relobj* object, const Symbol_value* psymval, elfcpp::Elf_Half addend) { This::template rela<16>(view, object, psymval, addend); } // Do a simple 16-bit PC relative REL relocation with the addend in // the section contents. static inline void pcrel16(unsigned char* view, elfcpp::Elf_Half value, typename elfcpp::Elf_types::Elf_Addr address) { This::template pcrel<16>(view, value, address); } static inline void pcrel16(unsigned char* view, const Sized_relobj* object, const Symbol_value* psymval, typename elfcpp::Elf_types::Elf_Addr address) { This::template pcrel<16>(view, object, psymval, address); } // Do a simple 16-bit PC relative RELA relocation with the addend in // the reloc. static inline void pcrela16(unsigned char* view, elfcpp::Elf_Half value, elfcpp::Elf_Half addend, typename elfcpp::Elf_types::Elf_Addr address) { This::template pcrela<16>(view, value, addend, address); } static inline void pcrela16(unsigned char* view, const Sized_relobj* object, const Symbol_value* psymval, elfcpp::Elf_Half addend, typename elfcpp::Elf_types::Elf_Addr address) { This::template pcrela<16>(view, object, psymval, addend, address); } // Do a simple 32-bit REL relocation with the addend in the section // contents. static inline void rel32(unsigned char* view, elfcpp::Elf_Word value) { This::template rel<32>(view, value); } static inline void rel32(unsigned char* view, const Sized_relobj* object, const Symbol_value* psymval) { This::template rel<32>(view, object, psymval); } // Do an 32-bit RELA relocation with the addend in the relocation. static inline void rela32(unsigned char* view, elfcpp::Elf_Word value, elfcpp::Elf_Word addend) { This::template rela<32>(view, value, addend); } static inline void rela32(unsigned char* view, const Sized_relobj* object, const Symbol_value* psymval, elfcpp::Elf_Word addend) { This::template rela<32>(view, object, psymval, addend); } // Do a simple 32-bit PC relative REL relocation with the addend in // the section contents. static inline void pcrel32(unsigned char* view, elfcpp::Elf_Word value, typename elfcpp::Elf_types::Elf_Addr address) { This::template pcrel<32>(view, value, address); } static inline void pcrel32(unsigned char* view, const Sized_relobj* object, const Symbol_value* psymval, typename elfcpp::Elf_types::Elf_Addr address) { This::template pcrel<32>(view, object, psymval, address); } // Do a simple 32-bit PC relative RELA relocation with the addend in // the relocation. static inline void pcrela32(unsigned char* view, elfcpp::Elf_Word value, elfcpp::Elf_Word addend, typename elfcpp::Elf_types::Elf_Addr address) { This::template pcrela<32>(view, value, addend, address); } static inline void pcrela32(unsigned char* view, const Sized_relobj* object, const Symbol_value* psymval, elfcpp::Elf_Word addend, typename elfcpp::Elf_types::Elf_Addr address) { This::template pcrela<32>(view, object, psymval, addend, address); } // Do a simple 64-bit REL relocation with the addend in the section // contents. static inline void rel64(unsigned char* view, elfcpp::Elf_Xword value) { This::template rel<64>(view, value); } static inline void rel64(unsigned char* view, const Sized_relobj* object, const Symbol_value* psymval) { This::template rel<64>(view, object, psymval); } // Do a 64-bit RELA relocation with the addend in the relocation. static inline void rela64(unsigned char* view, elfcpp::Elf_Xword value, elfcpp::Elf_Xword addend) { This::template rela<64>(view, value, addend); } static inline void rela64(unsigned char* view, const Sized_relobj* object, const Symbol_value* psymval, elfcpp::Elf_Xword addend) { This::template rela<64>(view, object, psymval, addend); } // Do a simple 64-bit PC relative REL relocation with the addend in // the section contents. static inline void pcrel64(unsigned char* view, elfcpp::Elf_Xword value, typename elfcpp::Elf_types::Elf_Addr address) { This::template pcrel<64>(view, value, address); } static inline void pcrel64(unsigned char* view, const Sized_relobj* object, const Symbol_value* psymval, typename elfcpp::Elf_types::Elf_Addr address) { This::template pcrel<64>(view, object, psymval, address); } // Do a simple 64-bit PC relative RELA relocation with the addend in // the relocation. static inline void pcrela64(unsigned char* view, elfcpp::Elf_Xword value, elfcpp::Elf_Xword addend, typename elfcpp::Elf_types::Elf_Addr address) { This::template pcrela<64>(view, value, addend, address); } static inline void pcrela64(unsigned char* view, const Sized_relobj* object, const Symbol_value* psymval, elfcpp::Elf_Xword addend, typename elfcpp::Elf_types::Elf_Addr address) { This::template pcrela<64>(view, object, psymval, addend, address); } }; // We try to avoid COPY relocations when possible. A COPY relocation // may be required when an executable refers to a variable defined in // a shared library. COPY relocations are problematic because they // tie the executable to the exact size of the variable in the shared // library. We can avoid them if all the references to the variable // are in a writeable section. In that case we can simply use dynamic // relocations. However, when scanning relocs, we don't know when we // see the relocation whether we will be forced to use a COPY // relocation or not. So we have to save the relocation during the // reloc scanning, and then emit it as a dynamic relocation if // necessary. This class implements that. It is used by the target // specific code. template class Copy_relocs { public: Copy_relocs() : entries_() { } // Return whether we need a COPY reloc for a reloc against GSYM, // which is being applied to section SHNDX in OBJECT. static bool need_copy_reloc(const General_options*, Relobj* object, unsigned int shndx, Sized_symbol* gsym); // Save a Rel against SYM for possible emission later. SHNDX is the // index of the section to which the reloc is being applied. void save(Symbol* sym, Relobj*, unsigned int shndx, Output_section* output_section, const elfcpp::Rel&); // Save a Rela against SYM for possible emission later. void save(Symbol* sym, Relobj*, unsigned int shndx, Output_section* output_section, const elfcpp::Rela&); // Return whether there are any relocs to emit. This also discards // entries which need not be emitted. bool any_to_emit(); // Emit relocs for each symbol which did not get a COPY reloc (i.e., // is still defined in the dynamic object). template void emit(Output_data_reloc*); private: typedef typename elfcpp::Elf_types::Elf_Addr Address; typedef typename elfcpp::Elf_types::Elf_Addr Addend; // This POD class holds the entries we are saving. class Copy_reloc_entry { public: Copy_reloc_entry(Symbol* sym, unsigned int reloc_type, Relobj* relobj, unsigned int shndx, Output_section* output_section, Address address, Addend addend) : sym_(sym), reloc_type_(reloc_type), relobj_(relobj), shndx_(shndx), output_section_(output_section), address_(address), addend_(addend) { } // Return whether we should emit this reloc. If we should not // emit, we clear it. bool should_emit(); // Emit this reloc. void emit(Output_data_reloc*); void emit(Output_data_reloc*); private: Symbol* sym_; unsigned int reloc_type_; Relobj* relobj_; unsigned int shndx_; Output_section* output_section_; Address address_; Addend addend_; }; // A list of relocs to be saved. typedef std::vector Copy_reloc_entries; // The list of relocs we are saving. Copy_reloc_entries entries_; }; // Track relocations while reading a section. This lets you ask for // the relocation at a certain offset, and see how relocs occur // between points of interest. template class Track_relocs { public: Track_relocs() : prelocs_(NULL), len_(0), pos_(0), reloc_size_(0) { } // Initialize the Track_relocs object. OBJECT is the object holding // the reloc section, RELOC_SHNDX is the section index of the reloc // section, and RELOC_TYPE is the type of the reloc section // (elfcpp::SHT_REL or elfcpp::SHT_RELA). This returns false if // something went wrong. bool initialize(Object* object, unsigned int reloc_shndx, unsigned int reloc_type); // Return the offset in the data section to which the next reloc // applies. THis returns -1 if there is no next reloc. off_t next_offset() const; // Return the symbol index of the next reloc. This returns -1U if // there is no next reloc. unsigned int next_symndx() const; // Advance to OFFSET within the data section, and return the number // of relocs which would be skipped. int advance(off_t offset); private: // The contents of the input object's reloc section. const unsigned char* prelocs_; // The length of the reloc section. off_t len_; // Our current position in the reloc section. off_t pos_; // The size of the relocs in the section. int reloc_size_; }; } // End namespace gold. #endif // !defined(GOLD_RELOC_H)