| 1 | // target.h -- target support for gold -*- C++ -*- |
| 2 | |
| 3 | // The abstract class Target is the interface for target specific |
| 4 | // support. It defines abstract methods which each target must |
| 5 | // implement. Typically there will be one target per processor, but |
| 6 | // in some cases it may be necessary to have subclasses. |
| 7 | |
| 8 | // For speed and consistency we want to use inline functions to handle |
| 9 | // relocation processing. So besides implementations of the abstract |
| 10 | // methods, each target is expected to define a template |
| 11 | // specialization of the relocation functions. |
| 12 | |
| 13 | #ifndef GOLD_TARGET_H |
| 14 | #define GOLD_TARGET_H |
| 15 | |
| 16 | #include <cassert> |
| 17 | |
| 18 | #include "elfcpp.h" |
| 19 | #include "symtab.h" |
| 20 | |
| 21 | namespace gold |
| 22 | { |
| 23 | |
| 24 | class General_options; |
| 25 | class Object; |
| 26 | template<int size, bool big_endian> |
| 27 | class Sized_object; |
| 28 | template<int size, bool big_endian> |
| 29 | struct Relocate_info; |
| 30 | |
| 31 | // The abstract class for target specific handling. |
| 32 | |
| 33 | class Target |
| 34 | { |
| 35 | public: |
| 36 | virtual ~Target() |
| 37 | { } |
| 38 | |
| 39 | // Return the bit size that this target implements. This should |
| 40 | // return 32 or 64. |
| 41 | int |
| 42 | get_size() const |
| 43 | { return this->pti_->size; } |
| 44 | |
| 45 | // Return whether this target is big-endian. |
| 46 | bool |
| 47 | is_big_endian() const |
| 48 | { return this->pti_->is_big_endian; } |
| 49 | |
| 50 | // Machine code to store in e_machine field of ELF header. |
| 51 | elfcpp::EM |
| 52 | machine_code() const |
| 53 | { return this->pti_->machine_code; } |
| 54 | |
| 55 | // Whether this target has a specific make_symbol function. |
| 56 | bool |
| 57 | has_make_symbol() const |
| 58 | { return this->pti_->has_make_symbol; } |
| 59 | |
| 60 | // Whether this target has a specific resolve function. |
| 61 | bool |
| 62 | has_resolve() const |
| 63 | { return this->pti_->has_resolve; } |
| 64 | |
| 65 | // Return the default address to use for the text segment. |
| 66 | uint64_t |
| 67 | text_segment_address() const |
| 68 | { return this->pti_->text_segment_address; } |
| 69 | |
| 70 | // Return the ABI specified page size. |
| 71 | uint64_t |
| 72 | abi_pagesize() const |
| 73 | { return this->pti_->abi_pagesize; } |
| 74 | |
| 75 | // Return the common page size used on actual systems. |
| 76 | uint64_t |
| 77 | common_pagesize() const |
| 78 | { return this->pti_->common_pagesize; } |
| 79 | |
| 80 | protected: |
| 81 | // This struct holds the constant information for a child class. We |
| 82 | // use a struct to avoid the overhead of virtual function calls for |
| 83 | // simple information. |
| 84 | struct Target_info |
| 85 | { |
| 86 | // Address size (32 or 64). |
| 87 | int size; |
| 88 | // Whether the target is big endian. |
| 89 | bool is_big_endian; |
| 90 | // The code to store in the e_machine field of the ELF header. |
| 91 | elfcpp::EM machine_code; |
| 92 | // Whether this target has a specific make_symbol function. |
| 93 | bool has_make_symbol; |
| 94 | // Whether this target has a specific resolve function. |
| 95 | bool has_resolve; |
| 96 | // The default text segment address. |
| 97 | uint64_t text_segment_address; |
| 98 | // The ABI specified page size. |
| 99 | uint64_t abi_pagesize; |
| 100 | // The common page size used by actual implementations. |
| 101 | uint64_t common_pagesize; |
| 102 | }; |
| 103 | |
| 104 | Target(const Target_info* pti) |
| 105 | : pti_(pti) |
| 106 | { } |
| 107 | |
| 108 | private: |
| 109 | Target(const Target&); |
| 110 | Target& operator=(const Target&); |
| 111 | |
| 112 | // The target information. |
| 113 | const Target_info* pti_; |
| 114 | }; |
| 115 | |
| 116 | // The abstract class for a specific size and endianness of target. |
| 117 | // Each actual target implementation class should derive from an |
| 118 | // instantiation of Sized_target. |
| 119 | |
| 120 | template<int size, bool big_endian> |
| 121 | class Sized_target : public Target |
| 122 | { |
| 123 | public: |
| 124 | // Make a new symbol table entry for the target. This should be |
| 125 | // overridden by a target which needs additional information in the |
| 126 | // symbol table. This will only be called if has_make_symbol() |
| 127 | // returns true. |
| 128 | virtual Sized_symbol<size>* |
| 129 | make_symbol() |
| 130 | { abort(); } |
| 131 | |
| 132 | // Resolve a symbol for the target. This should be overridden by a |
| 133 | // target which needs to take special action. TO is the |
| 134 | // pre-existing symbol. SYM is the new symbol, seen in OBJECT. |
| 135 | // This will only be called if has_resolve() returns true. |
| 136 | virtual void |
| 137 | resolve(Symbol*, const elfcpp::Sym<size, big_endian>&, Object*) |
| 138 | { abort(); } |
| 139 | |
| 140 | // Scan the relocs for a section, and record any information |
| 141 | // required for the symbol. OPTIONS is the command line options. |
| 142 | // SYMTAB is the symbol table. OBJECT is the object in which the |
| 143 | // section appears. SH_TYPE is the type of the relocation section, |
| 144 | // SHT_REL or SHT_RELA. PRELOCS points to the relocation data. |
| 145 | // RELOC_COUNT is the number of relocs. LOCAL_SYMBOL_COUNT is the |
| 146 | // number of local symbols. PLOCAL_SYMBOLS points to the local |
| 147 | // symbol data from OBJECT. GLOBAL_SYMBOLS is the array of pointers |
| 148 | // to the global symbol table from OBJECT. |
| 149 | virtual void |
| 150 | scan_relocs(const General_options& options, |
| 151 | Symbol_table* symtab, |
| 152 | Layout* layout, |
| 153 | Sized_object<size, big_endian>* object, |
| 154 | unsigned int sh_type, |
| 155 | const unsigned char* prelocs, |
| 156 | size_t reloc_count, |
| 157 | size_t local_symbol_count, |
| 158 | const unsigned char* plocal_symbols, |
| 159 | Symbol** global_symbols) = 0; |
| 160 | |
| 161 | // Relocate section data. SH_TYPE is the type of the relocation |
| 162 | // section, SHT_REL or SHT_RELA. PRELOCS points to the relocation |
| 163 | // information. RELOC_COUNT is the number of relocs. VIEW is a |
| 164 | // view into the output file holding the section contents, |
| 165 | // VIEW_ADDRESS is the virtual address of the view, and VIEW_SIZE is |
| 166 | // the size of the view. |
| 167 | virtual void |
| 168 | relocate_section(const Relocate_info<size, big_endian>*, |
| 169 | unsigned int sh_type, |
| 170 | const unsigned char* prelocs, |
| 171 | size_t reloc_count, |
| 172 | unsigned char* view, |
| 173 | typename elfcpp::Elf_types<size>::Elf_Addr view_address, |
| 174 | off_t view_size) = 0; |
| 175 | |
| 176 | protected: |
| 177 | Sized_target(const Target::Target_info* pti) |
| 178 | : Target(pti) |
| 179 | { |
| 180 | assert(pti->size == size); |
| 181 | assert(pti->is_big_endian ? big_endian : !big_endian); |
| 182 | } |
| 183 | }; |
| 184 | |
| 185 | } // End namespace gold. |
| 186 | |
| 187 | #endif // !defined(GOLD_TARGET_H) |