1 // reloc.h -- relocate input files for gold -*- C++ -*-
13 class General_options;
15 class Read_relocs_data;
23 template<int sh_type, bool dynamic, int size, bool big_endian>
24 class Output_data_reloc;
26 // A class to read the relocations for an object file, and then queue
27 // up a task to see if they require any GOT/PLT/COPY relocations in
30 class Read_relocs : public Task
33 // SYMTAB_LOCK is used to lock the symbol table. BLOCKER should be
34 // unblocked when the Scan_relocs task completes.
35 Read_relocs(const General_options& options, Symbol_table* symtab,
36 Layout* layout, Relobj* object, Task_token* symtab_lock,
38 : options_(options), symtab_(symtab), layout_(layout), object_(object),
39 symtab_lock_(symtab_lock), blocker_(blocker)
42 // The standard Task methods.
45 is_runnable(Workqueue*);
54 const General_options& options_;
55 Symbol_table* symtab_;
58 Task_token* symtab_lock_;
62 // Scan the relocations for an object to see if they require any
63 // GOT/PLT/COPY relocations.
65 class Scan_relocs : public Task
68 // SYMTAB_LOCK is used to lock the symbol table. BLOCKER should be
69 // unblocked when the task completes.
70 Scan_relocs(const General_options& options, Symbol_table* symtab,
71 Layout* layout, Relobj* object, Read_relocs_data* rd,
72 Task_token* symtab_lock, Task_token* blocker)
73 : options_(options), symtab_(symtab), layout_(layout), object_(object),
74 rd_(rd), symtab_lock_(symtab_lock), blocker_(blocker)
77 // The standard Task methods.
80 is_runnable(Workqueue*);
89 class Scan_relocs_locker;
91 const General_options& options_;
92 Symbol_table* symtab_;
95 Read_relocs_data* rd_;
96 Task_token* symtab_lock_;
100 // A class to perform all the relocations for an object file.
102 class Relocate_task : public Task
105 Relocate_task(const General_options& options, const Symbol_table* symtab,
106 const Layout* layout, Relobj* object, Output_file* of,
107 Task_token* final_blocker)
108 : options_(options), symtab_(symtab), layout_(layout), object_(object),
109 of_(of), final_blocker_(final_blocker)
112 // The standard Task methods.
115 is_runnable(Workqueue*);
124 class Relocate_locker;
126 const General_options& options_;
127 const Symbol_table* symtab_;
128 const Layout* layout_;
131 Task_token* final_blocker_;
134 // Standard relocation routines which are used on many targets. Here
135 // SIZE and BIG_ENDIAN refer to the target, not the relocation type.
137 template<int size, bool big_endian>
138 class Relocate_functions
141 // Do a simple relocation with the addend in the section contents.
142 // VALSIZE is the size of the value.
143 template<int valsize>
145 rel(unsigned char* view,
146 typename elfcpp::Swap<valsize, big_endian>::Valtype value)
148 typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
149 Valtype* wv = reinterpret_cast<Valtype*>(view);
150 Valtype x = elfcpp::Swap<valsize, big_endian>::readval(wv);
151 elfcpp::Swap<valsize, big_endian>::writeval(wv, x + value);
154 // Do a simple PC relative relocation with the addend in the section
155 // contents. VALSIZE is the size of the value.
156 template<int valsize>
158 pcrel(unsigned char* view,
159 typename elfcpp::Swap<valsize, big_endian>::Valtype value,
160 typename elfcpp::Elf_types<size>::Elf_Addr address)
162 typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
163 Valtype* wv = reinterpret_cast<Valtype*>(view);
164 Valtype x = elfcpp::Swap<valsize, big_endian>::readval(wv);
165 elfcpp::Swap<valsize, big_endian>::writeval(wv, x + value - address);
168 typedef Relocate_functions<size, big_endian> This;
171 // Do a simple 8-bit REL relocation with the addend in the object
174 rel8(unsigned char* view, unsigned char value)
176 This::template rel<8>(view, value);
179 // Do a simple 8-bit PC relative relocation with the addend in the
182 pcrel8(unsigned char* view, unsigned char value,
183 typename elfcpp::Elf_types<size>::Elf_Addr address)
185 This::template pcrel<8>(view, value, address);
188 // Do a simple 16-bit REL relocation with the addend in the object
191 rel16(unsigned char* view, elfcpp::Elf_Half value)
193 This::template rel<16>(view, value);
196 // Do a simple 32-bit PC relative REL relocation with the addend in
197 // the object file data.
199 pcrel16(unsigned char* view, elfcpp::Elf_Word value,
200 typename elfcpp::Elf_types<size>::Elf_Addr address)
202 This::template pcrel<16>(view, value, address);
205 // Do a simple 32-bit REL relocation with the addend in the section
208 rel32(unsigned char* view, elfcpp::Elf_Word value)
210 This::template rel<32>(view, value);
213 // Do a simple 32-bit PC relative REL relocation with the addend in
214 // the section contents.
216 pcrel32(unsigned char* view, elfcpp::Elf_Word value,
217 typename elfcpp::Elf_types<size>::Elf_Addr address)
219 This::template pcrel<32>(view, value, address);
222 // Do a simple 64-bit REL relocation with the addend in the section
225 rel64(unsigned char* view, elfcpp::Elf_Xword value)
227 This::template rel<64>(view, value);
230 // Do a simple 64-bit PC relative REL relocation with the addend in
231 // the section contents.
233 pcrel64(unsigned char* view, elfcpp::Elf_Xword value,
234 typename elfcpp::Elf_types<size>::Elf_Addr address)
236 This::template pcrel<64>(view, value, address);
240 // We try to avoid COPY relocations when possible. A COPY relocation
241 // may be required when an executable refers to a variable defined in
242 // a shared library. COPY relocations are problematic because they
243 // tie the executable to the exact size of the variable in the shared
244 // library. We can avoid them if all the references to the variable
245 // are in a writeable section. In that case we can simply use dynamic
246 // relocations. However, when scanning relocs, we don't know when we
247 // see the relocation whether we will be forced to use a COPY
248 // relocation or not. So we have to save the relocation during the
249 // reloc scanning, and then emit it as a dynamic relocation if
250 // necessary. This class implements that. It is used by the target
253 template<int size, bool big_endian>
261 // Return whether we need a COPY reloc for a reloc against GSYM,
262 // which is being applied to section SHNDX in OBJECT.
264 need_copy_reloc(const General_options*, Relobj* object, unsigned int shndx,
265 Sized_symbol<size>* gsym);
267 // Save a Rel against SYM for possible emission later. SHNDX is the
268 // index of the section to which the reloc is being applied.
270 save(Symbol* sym, Relobj*, unsigned int shndx,
271 const elfcpp::Rel<size, big_endian>&);
273 // Save a Rela against SYM for possible emission later.
275 save(Symbol* sym, Relobj*, unsigned int shndx,
276 const elfcpp::Rela<size, big_endian>&);
278 // Return whether there are any relocs to emit. This also discards
279 // entries which need not be emitted.
283 // Emit relocs for each symbol which did not get a COPY reloc (i.e.,
284 // is still defined in the dynamic object).
285 template<int sh_type>
287 emit(Output_data_reloc<sh_type, true, size, big_endian>*);
290 typedef typename elfcpp::Elf_types<size>::Elf_Addr Address;
291 typedef typename elfcpp::Elf_types<size>::Elf_Addr Addend;
293 // This POD class holds the entries we are saving.
294 class Copy_reloc_entry
297 Copy_reloc_entry(Symbol* sym, unsigned int reloc_type,
298 Relobj* relobj, unsigned int shndx,
299 Address address, Addend addend)
300 : sym_(sym), reloc_type_(reloc_type), relobj_(relobj),
301 shndx_(shndx), address_(address), addend_(addend)
304 // Return whether we should emit this reloc. If we should not
305 // emit, we clear it.
312 emit(Output_data_reloc<elfcpp::SHT_REL, true, size, big_endian>*);
315 emit(Output_data_reloc<elfcpp::SHT_RELA, true, size, big_endian>*);
319 unsigned int reloc_type_;
326 // A list of relocs to be saved.
327 typedef std::vector<Copy_reloc_entry> Copy_reloc_entries;
329 // The list of relocs we are saving.
330 Copy_reloc_entries entries_;
333 } // End namespace gold.
335 #endif // !defined(GOLD_RELOC_H)