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14bfc3f5 | 1 | // target.h -- target support for gold -*- C++ -*- |
bae7f79e | 2 | |
6d03d481 | 3 | // Copyright 2006, 2007, 2008, 2009 Free Software Foundation, Inc. |
6cb15b7f ILT |
4 | // Written by Ian Lance Taylor <iant@google.com>. |
5 | ||
6 | // This file is part of gold. | |
7 | ||
8 | // This program is free software; you can redistribute it and/or modify | |
9 | // it under the terms of the GNU General Public License as published by | |
10 | // the Free Software Foundation; either version 3 of the License, or | |
11 | // (at your option) any later version. | |
12 | ||
13 | // This program is distributed in the hope that it will be useful, | |
14 | // but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | // GNU General Public License for more details. | |
17 | ||
18 | // You should have received a copy of the GNU General Public License | |
19 | // along with this program; if not, write to the Free Software | |
20 | // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, | |
21 | // MA 02110-1301, USA. | |
22 | ||
bae7f79e ILT |
23 | // The abstract class Target is the interface for target specific |
24 | // support. It defines abstract methods which each target must | |
25 | // implement. Typically there will be one target per processor, but | |
26 | // in some cases it may be necessary to have subclasses. | |
27 | ||
28 | // For speed and consistency we want to use inline functions to handle | |
29 | // relocation processing. So besides implementations of the abstract | |
30 | // methods, each target is expected to define a template | |
31 | // specialization of the relocation functions. | |
32 | ||
33 | #ifndef GOLD_TARGET_H | |
34 | #define GOLD_TARGET_H | |
35 | ||
14bfc3f5 | 36 | #include "elfcpp.h" |
8851ecca | 37 | #include "options.h" |
cd72c291 | 38 | #include "parameters.h" |
14bfc3f5 | 39 | |
bae7f79e ILT |
40 | namespace gold |
41 | { | |
42 | ||
92e059d8 | 43 | class General_options; |
14bfc3f5 | 44 | class Object; |
61ba1cf9 | 45 | template<int size, bool big_endian> |
f6ce93d6 | 46 | class Sized_relobj; |
6a74a719 | 47 | class Relocatable_relocs; |
92e059d8 | 48 | template<int size, bool big_endian> |
730cdc88 | 49 | class Relocate_info; |
f6ce93d6 ILT |
50 | class Symbol; |
51 | template<int size> | |
52 | class Sized_symbol; | |
53 | class Symbol_table; | |
730cdc88 | 54 | class Output_section; |
14bfc3f5 ILT |
55 | |
56 | // The abstract class for target specific handling. | |
57 | ||
bae7f79e ILT |
58 | class Target |
59 | { | |
60 | public: | |
14bfc3f5 ILT |
61 | virtual ~Target() |
62 | { } | |
63 | ||
64 | // Return the bit size that this target implements. This should | |
65 | // return 32 or 64. | |
66 | int | |
67 | get_size() const | |
75f65a3e | 68 | { return this->pti_->size; } |
14bfc3f5 ILT |
69 | |
70 | // Return whether this target is big-endian. | |
71 | bool | |
72 | is_big_endian() const | |
75f65a3e | 73 | { return this->pti_->is_big_endian; } |
14bfc3f5 | 74 | |
61ba1cf9 ILT |
75 | // Machine code to store in e_machine field of ELF header. |
76 | elfcpp::EM | |
77 | machine_code() const | |
78 | { return this->pti_->machine_code; } | |
79 | ||
14bfc3f5 ILT |
80 | // Whether this target has a specific make_symbol function. |
81 | bool | |
82 | has_make_symbol() const | |
75f65a3e | 83 | { return this->pti_->has_make_symbol; } |
14bfc3f5 ILT |
84 | |
85 | // Whether this target has a specific resolve function. | |
86 | bool | |
87 | has_resolve() const | |
75f65a3e ILT |
88 | { return this->pti_->has_resolve; } |
89 | ||
c51e6221 ILT |
90 | // Whether this target has a specific code fill function. |
91 | bool | |
92 | has_code_fill() const | |
93 | { return this->pti_->has_code_fill; } | |
94 | ||
dbe717ef ILT |
95 | // Return the default name of the dynamic linker. |
96 | const char* | |
97 | dynamic_linker() const | |
98 | { return this->pti_->dynamic_linker; } | |
99 | ||
75f65a3e ILT |
100 | // Return the default address to use for the text segment. |
101 | uint64_t | |
0c5e9c22 ILT |
102 | default_text_segment_address() const |
103 | { return this->pti_->default_text_segment_address; } | |
75f65a3e ILT |
104 | |
105 | // Return the ABI specified page size. | |
106 | uint64_t | |
107 | abi_pagesize() const | |
cd72c291 | 108 | { |
8851ecca ILT |
109 | if (parameters->options().max_page_size() > 0) |
110 | return parameters->options().max_page_size(); | |
cd72c291 ILT |
111 | else |
112 | return this->pti_->abi_pagesize; | |
113 | } | |
75f65a3e ILT |
114 | |
115 | // Return the common page size used on actual systems. | |
116 | uint64_t | |
117 | common_pagesize() const | |
cd72c291 | 118 | { |
8851ecca ILT |
119 | if (parameters->options().common_page_size() > 0) |
120 | return std::min(parameters->options().common_page_size(), | |
cd72c291 ILT |
121 | this->abi_pagesize()); |
122 | else | |
123 | return std::min(this->pti_->common_pagesize, | |
124 | this->abi_pagesize()); | |
125 | } | |
14bfc3f5 | 126 | |
35cdfc9a ILT |
127 | // If we see some object files with .note.GNU-stack sections, and |
128 | // some objects files without them, this returns whether we should | |
129 | // consider the object files without them to imply that the stack | |
130 | // should be executable. | |
131 | bool | |
132 | is_default_stack_executable() const | |
133 | { return this->pti_->is_default_stack_executable; } | |
134 | ||
0864d551 ILT |
135 | // Return a character which may appear as a prefix for a wrap |
136 | // symbol. If this character appears, we strip it when checking for | |
137 | // wrapping and add it back when forming the final symbol name. | |
138 | // This should be '\0' if not special prefix is required, which is | |
139 | // the normal case. | |
140 | char | |
141 | wrap_char() const | |
142 | { return this->pti_->wrap_char; } | |
143 | ||
8a5e3e08 ILT |
144 | // Return the special section index which indicates a small common |
145 | // symbol. This will return SHN_UNDEF if there are no small common | |
146 | // symbols. | |
147 | elfcpp::Elf_Half | |
148 | small_common_shndx() const | |
149 | { return this->pti_->small_common_shndx; } | |
150 | ||
151 | // Return values to add to the section flags for the section holding | |
152 | // small common symbols. | |
153 | elfcpp::Elf_Xword | |
154 | small_common_section_flags() const | |
155 | { | |
156 | gold_assert(this->pti_->small_common_shndx != elfcpp::SHN_UNDEF); | |
157 | return this->pti_->small_common_section_flags; | |
158 | } | |
159 | ||
160 | // Return the special section index which indicates a large common | |
161 | // symbol. This will return SHN_UNDEF if there are no large common | |
162 | // symbols. | |
163 | elfcpp::Elf_Half | |
164 | large_common_shndx() const | |
165 | { return this->pti_->large_common_shndx; } | |
166 | ||
167 | // Return values to add to the section flags for the section holding | |
168 | // large common symbols. | |
169 | elfcpp::Elf_Xword | |
170 | large_common_section_flags() const | |
171 | { | |
172 | gold_assert(this->pti_->large_common_shndx != elfcpp::SHN_UNDEF); | |
173 | return this->pti_->large_common_section_flags; | |
174 | } | |
175 | ||
176 | // This hook is called when an output section is created. | |
177 | void | |
178 | new_output_section(Output_section* os) const | |
179 | { this->do_new_output_section(os); } | |
180 | ||
5a6f7e2d ILT |
181 | // This is called to tell the target to complete any sections it is |
182 | // handling. After this all sections must have their final size. | |
183 | void | |
7e1edb90 ILT |
184 | finalize_sections(Layout* layout) |
185 | { return this->do_finalize_sections(layout); } | |
5a6f7e2d | 186 | |
ab5c9e90 ILT |
187 | // Return the value to use for a global symbol which needs a special |
188 | // value in the dynamic symbol table. This will only be called if | |
189 | // the backend first calls symbol->set_needs_dynsym_value(). | |
190 | uint64_t | |
191 | dynsym_value(const Symbol* sym) const | |
192 | { return this->do_dynsym_value(sym); } | |
193 | ||
c51e6221 ILT |
194 | // Return a string to use to fill out a code section. This is |
195 | // basically one or more NOPS which must fill out the specified | |
196 | // length in bytes. | |
197 | std::string | |
8851ecca | 198 | code_fill(section_size_type length) const |
c51e6221 ILT |
199 | { return this->do_code_fill(length); } |
200 | ||
9a2d6984 ILT |
201 | // Return whether SYM is known to be defined by the ABI. This is |
202 | // used to avoid inappropriate warnings about undefined symbols. | |
203 | bool | |
9c2d0ef9 | 204 | is_defined_by_abi(const Symbol* sym) const |
9a2d6984 ILT |
205 | { return this->do_is_defined_by_abi(sym); } |
206 | ||
36959681 ILT |
207 | // Adjust the output file header before it is written out. VIEW |
208 | // points to the header in external form. LEN is the length. | |
209 | void | |
210 | adjust_elf_header(unsigned char* view, int len) const | |
211 | { return this->do_adjust_elf_header(view, len); } | |
212 | ||
bb04269c DK |
213 | // Return whether NAME is a local label name. This is used to implement the |
214 | // --discard-locals options. | |
215 | bool | |
216 | is_local_label_name(const char* name) const | |
217 | { return this->do_is_local_label_name(name); } | |
218 | ||
14bfc3f5 | 219 | protected: |
75f65a3e ILT |
220 | // This struct holds the constant information for a child class. We |
221 | // use a struct to avoid the overhead of virtual function calls for | |
222 | // simple information. | |
223 | struct Target_info | |
224 | { | |
225 | // Address size (32 or 64). | |
226 | int size; | |
227 | // Whether the target is big endian. | |
228 | bool is_big_endian; | |
61ba1cf9 ILT |
229 | // The code to store in the e_machine field of the ELF header. |
230 | elfcpp::EM machine_code; | |
75f65a3e ILT |
231 | // Whether this target has a specific make_symbol function. |
232 | bool has_make_symbol; | |
233 | // Whether this target has a specific resolve function. | |
234 | bool has_resolve; | |
c51e6221 ILT |
235 | // Whether this target has a specific code fill function. |
236 | bool has_code_fill; | |
35cdfc9a ILT |
237 | // Whether an object file with no .note.GNU-stack sections implies |
238 | // that the stack should be executable. | |
239 | bool is_default_stack_executable; | |
0864d551 ILT |
240 | // Prefix character to strip when checking for wrapping. |
241 | char wrap_char; | |
dbe717ef ILT |
242 | // The default dynamic linker name. |
243 | const char* dynamic_linker; | |
75f65a3e | 244 | // The default text segment address. |
0c5e9c22 | 245 | uint64_t default_text_segment_address; |
75f65a3e ILT |
246 | // The ABI specified page size. |
247 | uint64_t abi_pagesize; | |
248 | // The common page size used by actual implementations. | |
249 | uint64_t common_pagesize; | |
8a5e3e08 ILT |
250 | // The special section index for small common symbols; SHN_UNDEF |
251 | // if none. | |
252 | elfcpp::Elf_Half small_common_shndx; | |
253 | // The special section index for large common symbols; SHN_UNDEF | |
254 | // if none. | |
255 | elfcpp::Elf_Half large_common_shndx; | |
256 | // Section flags for small common section. | |
257 | elfcpp::Elf_Xword small_common_section_flags; | |
258 | // Section flags for large common section. | |
259 | elfcpp::Elf_Xword large_common_section_flags; | |
75f65a3e ILT |
260 | }; |
261 | ||
262 | Target(const Target_info* pti) | |
263 | : pti_(pti) | |
14bfc3f5 ILT |
264 | { } |
265 | ||
8a5e3e08 ILT |
266 | // Virtual function which may be implemented by the child class. |
267 | virtual void | |
268 | do_new_output_section(Output_section*) const | |
269 | { } | |
270 | ||
5a6f7e2d ILT |
271 | // Virtual function which may be implemented by the child class. |
272 | virtual void | |
7e1edb90 | 273 | do_finalize_sections(Layout*) |
5a6f7e2d ILT |
274 | { } |
275 | ||
ab5c9e90 ILT |
276 | // Virtual function which may be implemented by the child class. |
277 | virtual uint64_t | |
278 | do_dynsym_value(const Symbol*) const | |
279 | { gold_unreachable(); } | |
280 | ||
c51e6221 ILT |
281 | // Virtual function which must be implemented by the child class if |
282 | // needed. | |
283 | virtual std::string | |
8851ecca | 284 | do_code_fill(section_size_type) const |
c51e6221 ILT |
285 | { gold_unreachable(); } |
286 | ||
9a2d6984 ILT |
287 | // Virtual function which may be implemented by the child class. |
288 | virtual bool | |
9c2d0ef9 | 289 | do_is_defined_by_abi(const Symbol*) const |
9a2d6984 ILT |
290 | { return false; } |
291 | ||
36959681 ILT |
292 | // Adjust the output file header before it is written out. VIEW |
293 | // points to the header in external form. LEN is the length, and | |
294 | // will be one of the values of elfcpp::Elf_sizes<size>::ehdr_size. | |
295 | // By default, we do nothing. | |
296 | virtual void | |
297 | do_adjust_elf_header(unsigned char*, int) const | |
298 | { } | |
299 | ||
bb04269c DK |
300 | // Virtual function which may be overriden by the child class. |
301 | virtual bool | |
302 | do_is_local_label_name(const char*) const; | |
303 | ||
14bfc3f5 ILT |
304 | private: |
305 | Target(const Target&); | |
306 | Target& operator=(const Target&); | |
307 | ||
75f65a3e ILT |
308 | // The target information. |
309 | const Target_info* pti_; | |
bae7f79e ILT |
310 | }; |
311 | ||
14bfc3f5 ILT |
312 | // The abstract class for a specific size and endianness of target. |
313 | // Each actual target implementation class should derive from an | |
314 | // instantiation of Sized_target. | |
315 | ||
316 | template<int size, bool big_endian> | |
317 | class Sized_target : public Target | |
318 | { | |
319 | public: | |
320 | // Make a new symbol table entry for the target. This should be | |
321 | // overridden by a target which needs additional information in the | |
322 | // symbol table. This will only be called if has_make_symbol() | |
323 | // returns true. | |
324 | virtual Sized_symbol<size>* | |
14b31740 | 325 | make_symbol() const |
a3ad94ed | 326 | { gold_unreachable(); } |
14bfc3f5 ILT |
327 | |
328 | // Resolve a symbol for the target. This should be overridden by a | |
329 | // target which needs to take special action. TO is the | |
330 | // pre-existing symbol. SYM is the new symbol, seen in OBJECT. | |
14b31740 ILT |
331 | // VERSION is the version of SYM. This will only be called if |
332 | // has_resolve() returns true. | |
14bfc3f5 | 333 | virtual void |
14b31740 ILT |
334 | resolve(Symbol*, const elfcpp::Sym<size, big_endian>&, Object*, |
335 | const char*) | |
a3ad94ed | 336 | { gold_unreachable(); } |
14bfc3f5 | 337 | |
6d03d481 ST |
338 | // Process the relocs for a section, and record information of the |
339 | // mapping from source to destination sections. This mapping is later | |
340 | // used to determine unreferenced garbage sections. This procedure is | |
341 | // only called during garbage collection. | |
342 | virtual void | |
343 | gc_process_relocs(const General_options& options, | |
344 | Symbol_table* symtab, | |
345 | Layout* layout, | |
346 | Sized_relobj<size, big_endian>* object, | |
347 | unsigned int data_shndx, | |
348 | unsigned int sh_type, | |
349 | const unsigned char* prelocs, | |
350 | size_t reloc_count, | |
351 | Output_section* output_section, | |
352 | bool needs_special_offset_handling, | |
353 | size_t local_symbol_count, | |
354 | const unsigned char* plocal_symbols) = 0; | |
355 | ||
92e059d8 ILT |
356 | // Scan the relocs for a section, and record any information |
357 | // required for the symbol. OPTIONS is the command line options. | |
358 | // SYMTAB is the symbol table. OBJECT is the object in which the | |
a3ad94ed ILT |
359 | // section appears. DATA_SHNDX is the section index that these |
360 | // relocs apply to. SH_TYPE is the type of the relocation section, | |
92e059d8 ILT |
361 | // SHT_REL or SHT_RELA. PRELOCS points to the relocation data. |
362 | // RELOC_COUNT is the number of relocs. LOCAL_SYMBOL_COUNT is the | |
730cdc88 ILT |
363 | // number of local symbols. OUTPUT_SECTION is the output section. |
364 | // NEEDS_SPECIAL_OFFSET_HANDLING is true if offsets to the output | |
365 | // sections are not mapped as usual. PLOCAL_SYMBOLS points to the | |
366 | // local symbol data from OBJECT. GLOBAL_SYMBOLS is the array of | |
367 | // pointers to the global symbol table from OBJECT. | |
61ba1cf9 | 368 | virtual void |
92e059d8 ILT |
369 | scan_relocs(const General_options& options, |
370 | Symbol_table* symtab, | |
ead1e424 | 371 | Layout* layout, |
f6ce93d6 | 372 | Sized_relobj<size, big_endian>* object, |
a3ad94ed | 373 | unsigned int data_shndx, |
92e059d8 ILT |
374 | unsigned int sh_type, |
375 | const unsigned char* prelocs, | |
376 | size_t reloc_count, | |
730cdc88 ILT |
377 | Output_section* output_section, |
378 | bool needs_special_offset_handling, | |
92e059d8 | 379 | size_t local_symbol_count, |
730cdc88 | 380 | const unsigned char* plocal_symbols) = 0; |
92e059d8 ILT |
381 | |
382 | // Relocate section data. SH_TYPE is the type of the relocation | |
383 | // section, SHT_REL or SHT_RELA. PRELOCS points to the relocation | |
730cdc88 ILT |
384 | // information. RELOC_COUNT is the number of relocs. |
385 | // OUTPUT_SECTION is the output section. | |
386 | // NEEDS_SPECIAL_OFFSET_HANDLING is true if offsets must be mapped | |
387 | // to correspond to the output section. VIEW is a view into the | |
388 | // output file holding the section contents, VIEW_ADDRESS is the | |
389 | // virtual address of the view, and VIEW_SIZE is the size of the | |
390 | // view. If NEEDS_SPECIAL_OFFSET_HANDLING is true, the VIEW_xx | |
391 | // parameters refer to the complete output section data, not just | |
392 | // the input section data. | |
92e059d8 ILT |
393 | virtual void |
394 | relocate_section(const Relocate_info<size, big_endian>*, | |
395 | unsigned int sh_type, | |
396 | const unsigned char* prelocs, | |
397 | size_t reloc_count, | |
730cdc88 ILT |
398 | Output_section* output_section, |
399 | bool needs_special_offset_handling, | |
92e059d8 ILT |
400 | unsigned char* view, |
401 | typename elfcpp::Elf_types<size>::Elf_Addr view_address, | |
fe8718a4 | 402 | section_size_type view_size) = 0; |
61ba1cf9 | 403 | |
6a74a719 ILT |
404 | // Scan the relocs during a relocatable link. The parameters are |
405 | // like scan_relocs, with an additional Relocatable_relocs | |
406 | // parameter, used to record the disposition of the relocs. | |
407 | virtual void | |
408 | scan_relocatable_relocs(const General_options& options, | |
409 | Symbol_table* symtab, | |
410 | Layout* layout, | |
411 | Sized_relobj<size, big_endian>* object, | |
412 | unsigned int data_shndx, | |
413 | unsigned int sh_type, | |
414 | const unsigned char* prelocs, | |
415 | size_t reloc_count, | |
416 | Output_section* output_section, | |
417 | bool needs_special_offset_handling, | |
418 | size_t local_symbol_count, | |
419 | const unsigned char* plocal_symbols, | |
420 | Relocatable_relocs*) = 0; | |
421 | ||
422 | // Relocate a section during a relocatable link. The parameters are | |
423 | // like relocate_section, with additional parameters for the view of | |
424 | // the output reloc section. | |
425 | virtual void | |
426 | relocate_for_relocatable(const Relocate_info<size, big_endian>*, | |
427 | unsigned int sh_type, | |
428 | const unsigned char* prelocs, | |
429 | size_t reloc_count, | |
430 | Output_section* output_section, | |
431 | off_t offset_in_output_section, | |
432 | const Relocatable_relocs*, | |
433 | unsigned char* view, | |
434 | typename elfcpp::Elf_types<size>::Elf_Addr | |
435 | view_address, | |
436 | section_size_type view_size, | |
437 | unsigned char* reloc_view, | |
438 | section_size_type reloc_view_size) = 0; | |
439 | ||
14bfc3f5 | 440 | protected: |
75f65a3e ILT |
441 | Sized_target(const Target::Target_info* pti) |
442 | : Target(pti) | |
443 | { | |
a3ad94ed ILT |
444 | gold_assert(pti->size == size); |
445 | gold_assert(pti->is_big_endian ? big_endian : !big_endian); | |
75f65a3e | 446 | } |
14bfc3f5 | 447 | }; |
bae7f79e ILT |
448 | |
449 | } // End namespace gold. | |
450 | ||
451 | #endif // !defined(GOLD_TARGET_H) |