Commit | Line | Data |
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14bfc3f5 ILT |
1 | // resolve.cc -- symbol resolution for gold |
2 | ||
3 | #include "gold.h" | |
4 | ||
5 | #include "elfcpp.h" | |
6 | #include "target.h" | |
7 | #include "object.h" | |
8 | #include "symtab.h" | |
9 | ||
10 | namespace gold | |
11 | { | |
12 | ||
1564db8d ILT |
13 | // Symbol methods used in this file. |
14 | ||
15 | // Override the fields in Symbol. | |
16 | ||
17 | template<int size, bool big_endian> | |
18 | void | |
19 | Symbol::override_base(const elfcpp::Sym<size, big_endian>& sym, | |
20 | Object* object) | |
21 | { | |
22 | this->object_ = object; | |
23 | this->shnum_ = sym.get_st_shndx(); // FIXME: Handle SHN_XINDEX. | |
24 | this->type_ = sym.get_st_type(); | |
25 | this->binding_ = sym.get_st_bind(); | |
26 | this->visibility_ = sym.get_st_visibility(); | |
27 | this->other_ = sym.get_st_nonvis(); | |
28 | } | |
29 | ||
30 | // Override the fields in Sized_symbol. | |
31 | ||
32 | template<int size> | |
33 | template<bool big_endian> | |
34 | void | |
35 | Sized_symbol<size>::override(const elfcpp::Sym<size, big_endian>& sym, | |
36 | Object* object) | |
37 | { | |
38 | this->override_base(sym, object); | |
39 | this->value_ = sym.get_st_value(); | |
40 | this->size_ = sym.get_st_size(); | |
41 | } | |
42 | ||
14bfc3f5 ILT |
43 | // Resolve a symbol. This is called the second and subsequent times |
44 | // we see a symbol. TO is the pre-existing symbol. SYM is the new | |
45 | // symbol, seen in OBJECT. | |
46 | ||
47 | template<int size, bool big_endian> | |
48 | void | |
1564db8d | 49 | Symbol_table::resolve(Sized_symbol<size>* to, |
14bfc3f5 ILT |
50 | const elfcpp::Sym<size, big_endian>& sym, |
51 | Object* object) | |
52 | { | |
53 | if (object->target()->has_resolve()) | |
54 | { | |
55 | object->sized_target<size, big_endian>()->resolve(to, sym, object); | |
56 | return; | |
57 | } | |
58 | ||
59 | // Build a little code for each symbol. | |
60 | // Bit 0: 0 for global, 1 for weak. | |
61 | // Bit 1: 0 for regular object, 1 for shared object | |
62 | // Bits 2-3: 0 for normal, 1 for undefined, 2 for common | |
63 | // This gives us values from 0 to 11: | |
64 | ||
65 | enum | |
66 | { | |
67 | DEF = 0, | |
68 | WEAK_DEF = 1, | |
69 | DYN_DEF = 2, | |
70 | DYN_WEAK_DEF = 3, | |
71 | UNDEF = 4, | |
72 | WEAK_UNDEF = 5, | |
73 | DYN_UNDEF = 6, | |
74 | DYN_WEAK_UNDEF = 7, | |
75 | COMMON = 8, | |
76 | WEAK_COMMON = 9, | |
77 | DYN_COMMON = 10, | |
78 | DYN_WEAK_COMMON = 11 | |
79 | }; | |
80 | ||
81 | int tobits; | |
82 | switch (to->binding()) | |
83 | { | |
84 | case elfcpp::STB_GLOBAL: | |
85 | tobits = 0; | |
86 | break; | |
87 | ||
88 | case elfcpp::STB_WEAK: | |
89 | tobits = 1; | |
90 | break; | |
91 | ||
92 | case elfcpp::STB_LOCAL: | |
93 | // We should only see externally visible symbols in the symbol | |
94 | // table. | |
95 | abort(); | |
96 | ||
97 | default: | |
98 | // Any target which wants to handle STB_LOOS, etc., needs to | |
99 | // define a resolve method. | |
100 | abort(); | |
101 | } | |
102 | ||
103 | if (to->object() != NULL && to->object()->is_dynamic()) | |
104 | tobits |= (1 << 1); | |
105 | ||
106 | switch (to->shnum()) | |
107 | { | |
108 | case elfcpp::SHN_UNDEF: | |
109 | tobits |= (1 << 2); | |
110 | break; | |
111 | ||
112 | case elfcpp::SHN_COMMON: | |
113 | tobits |= (2 << 2); | |
114 | break; | |
115 | ||
116 | default: | |
1564db8d ILT |
117 | if (to->type() == elfcpp::STT_COMMON) |
118 | tobits |= (2 << 2); | |
14bfc3f5 ILT |
119 | break; |
120 | } | |
121 | ||
122 | int frombits; | |
123 | switch (sym.get_st_bind()) | |
124 | { | |
125 | case elfcpp::STB_GLOBAL: | |
126 | frombits = 0; | |
127 | break; | |
128 | ||
129 | case elfcpp::STB_WEAK: | |
130 | frombits = 1; | |
131 | break; | |
132 | ||
133 | case elfcpp::STB_LOCAL: | |
134 | fprintf(stderr, | |
135 | _("%s: %s: invalid STB_LOCAL symbol %s in external symbols\n"), | |
136 | program_name, object->name().c_str(), to->name()); | |
137 | gold_exit(false); | |
138 | ||
139 | default: | |
140 | fprintf(stderr, | |
141 | _("%s: %s: unsupported symbol binding %d for symbol %s\n"), | |
142 | program_name, object->name().c_str(), | |
143 | static_cast<int>(sym.get_st_bind()), to->name()); | |
144 | gold_exit(false); | |
145 | } | |
146 | ||
147 | if (object->is_dynamic()) | |
1564db8d ILT |
148 | { |
149 | frombits |= (1 << 1); | |
150 | ||
151 | // Record that we've seen this symbol in a dynamic object. | |
152 | to->set_in_dyn(); | |
153 | } | |
14bfc3f5 ILT |
154 | |
155 | switch (sym.get_st_shndx()) | |
156 | { | |
157 | case elfcpp::SHN_UNDEF: | |
158 | frombits |= (1 << 2); | |
159 | break; | |
160 | ||
161 | case elfcpp::SHN_COMMON: | |
162 | frombits |= (2 << 2); | |
163 | break; | |
164 | ||
165 | default: | |
1564db8d ILT |
166 | if (sym.get_st_type() == elfcpp::STT_COMMON) |
167 | frombits |= (2 << 2); | |
14bfc3f5 ILT |
168 | break; |
169 | } | |
170 | ||
1564db8d ILT |
171 | // FIXME: Warn if either but not both of TO and SYM are STT_TLS. |
172 | ||
14bfc3f5 ILT |
173 | // We use a giant switch table for symbol resolution. This code is |
174 | // unwieldy, but: 1) it is efficient; 2) we definitely handle all | |
175 | // cases; 3) it is easy to change the handling of a particular case. | |
176 | // The alternative would be a series of conditionals, but it is easy | |
177 | // to get the ordering wrong. This could also be done as a table, | |
178 | // but that is no easier to understand than this large switch | |
179 | // statement. | |
180 | ||
181 | switch (tobits * 16 + frombits) | |
182 | { | |
183 | case DEF * 16 + DEF: | |
184 | // Two definitions of the same symbol. | |
185 | fprintf(stderr, "%s: %s: multiple definition of %s\n", | |
186 | program_name, object->name().c_str(), to->name()); | |
187 | // FIXME: Report locations. Record that we have seen an error. | |
188 | return; | |
189 | ||
190 | case WEAK_DEF * 16 + DEF: | |
1564db8d ILT |
191 | // We've seen a weak definition, and now we see a strong |
192 | // definition. In the original SVR4 linker, this was treated as | |
193 | // a multiple definition error. In the Solaris linker and the | |
194 | // GNU linker, a weak definition followed by a regular | |
195 | // definition causes the weak definition to be overridden. We | |
196 | // are currently compatible with the GNU linker. In the future | |
197 | // we should add a target specific option to change this. | |
198 | // FIXME. | |
199 | to->override(sym, object); | |
14bfc3f5 ILT |
200 | return; |
201 | ||
202 | case DYN_DEF * 16 + DEF: | |
203 | case DYN_WEAK_DEF * 16 + DEF: | |
1564db8d ILT |
204 | // We've seen a definition in a dynamic object, and now we see a |
205 | // definition in a regular object. The definition in the | |
206 | // regular object overrides the definition in the dynamic | |
207 | // object. | |
208 | to->override(sym, object); | |
209 | return; | |
210 | ||
14bfc3f5 ILT |
211 | case UNDEF * 16 + DEF: |
212 | case WEAK_UNDEF * 16 + DEF: | |
213 | case DYN_UNDEF * 16 + DEF: | |
214 | case DYN_WEAK_UNDEF * 16 + DEF: | |
1564db8d ILT |
215 | // We've seen an undefined reference, and now we see a |
216 | // definition. We use the definition. | |
217 | to->override(sym, object); | |
218 | return; | |
219 | ||
14bfc3f5 ILT |
220 | case COMMON * 16 + DEF: |
221 | case WEAK_COMMON * 16 + DEF: | |
222 | case DYN_COMMON * 16 + DEF: | |
223 | case DYN_WEAK_COMMON * 16 + DEF: | |
1564db8d ILT |
224 | // We've seen a common symbol and now we see a definition. The |
225 | // definition overrides. FIXME: We should optionally issue a | |
226 | // warning. | |
227 | to->override(sym, object); | |
228 | return; | |
14bfc3f5 ILT |
229 | |
230 | case DEF * 16 + WEAK_DEF: | |
231 | case WEAK_DEF * 16 + WEAK_DEF: | |
1564db8d ILT |
232 | // We've seen a definition and now we see a weak definition. We |
233 | // ignore the new weak definition. | |
234 | return; | |
235 | ||
14bfc3f5 ILT |
236 | case DYN_DEF * 16 + WEAK_DEF: |
237 | case DYN_WEAK_DEF * 16 + WEAK_DEF: | |
1564db8d ILT |
238 | // We've seen a dynamic definition and now we see a regular weak |
239 | // definition. The regular weak definition overrides. | |
240 | to->override(sym, object); | |
241 | return; | |
242 | ||
14bfc3f5 ILT |
243 | case UNDEF * 16 + WEAK_DEF: |
244 | case WEAK_UNDEF * 16 + WEAK_DEF: | |
245 | case DYN_UNDEF * 16 + WEAK_DEF: | |
246 | case DYN_WEAK_UNDEF * 16 + WEAK_DEF: | |
1564db8d ILT |
247 | // A weak definition of a currently undefined symbol. |
248 | to->override(sym, object); | |
249 | return; | |
250 | ||
14bfc3f5 ILT |
251 | case COMMON * 16 + WEAK_DEF: |
252 | case WEAK_COMMON * 16 + WEAK_DEF: | |
1564db8d ILT |
253 | // A weak definition does not override a common definition. |
254 | return; | |
255 | ||
14bfc3f5 ILT |
256 | case DYN_COMMON * 16 + WEAK_DEF: |
257 | case DYN_WEAK_COMMON * 16 + WEAK_DEF: | |
1564db8d ILT |
258 | // A weak definition does override a definition in a dynamic |
259 | // object. FIXME: We should optionally issue a warning. | |
260 | to->override(sym, object); | |
261 | return; | |
14bfc3f5 ILT |
262 | |
263 | case DEF * 16 + DYN_DEF: | |
264 | case WEAK_DEF * 16 + DYN_DEF: | |
265 | case DYN_DEF * 16 + DYN_DEF: | |
266 | case DYN_WEAK_DEF * 16 + DYN_DEF: | |
1564db8d ILT |
267 | // Ignore a dynamic definition if we already have a definition. |
268 | return; | |
269 | ||
14bfc3f5 ILT |
270 | case UNDEF * 16 + DYN_DEF: |
271 | case WEAK_UNDEF * 16 + DYN_DEF: | |
272 | case DYN_UNDEF * 16 + DYN_DEF: | |
273 | case DYN_WEAK_UNDEF * 16 + DYN_DEF: | |
1564db8d ILT |
274 | // Use a dynamic definition if we have a reference. |
275 | to->override(sym, object); | |
276 | return; | |
277 | ||
14bfc3f5 ILT |
278 | case COMMON * 16 + DYN_DEF: |
279 | case WEAK_COMMON * 16 + DYN_DEF: | |
280 | case DYN_COMMON * 16 + DYN_DEF: | |
281 | case DYN_WEAK_COMMON * 16 + DYN_DEF: | |
1564db8d ILT |
282 | // Ignore a dynamic definition if we already have a common |
283 | // definition. | |
284 | return; | |
14bfc3f5 ILT |
285 | |
286 | case DEF * 16 + DYN_WEAK_DEF: | |
287 | case WEAK_DEF * 16 + DYN_WEAK_DEF: | |
288 | case DYN_DEF * 16 + DYN_WEAK_DEF: | |
289 | case DYN_WEAK_DEF * 16 + DYN_WEAK_DEF: | |
1564db8d ILT |
290 | // Ignore a weak dynamic definition if we already have a |
291 | // definition. | |
292 | return; | |
293 | ||
14bfc3f5 ILT |
294 | case UNDEF * 16 + DYN_WEAK_DEF: |
295 | case WEAK_UNDEF * 16 + DYN_WEAK_DEF: | |
296 | case DYN_UNDEF * 16 + DYN_WEAK_DEF: | |
297 | case DYN_WEAK_UNDEF * 16 + DYN_WEAK_DEF: | |
1564db8d ILT |
298 | // Use a weak dynamic definition if we have a reference. |
299 | to->override(sym, object); | |
300 | return; | |
301 | ||
14bfc3f5 ILT |
302 | case COMMON * 16 + DYN_WEAK_DEF: |
303 | case WEAK_COMMON * 16 + DYN_WEAK_DEF: | |
304 | case DYN_COMMON * 16 + DYN_WEAK_DEF: | |
305 | case DYN_WEAK_COMMON * 16 + DYN_WEAK_DEF: | |
1564db8d ILT |
306 | // Ignore a weak dynamic definition if we already have a common |
307 | // definition. | |
308 | return; | |
14bfc3f5 ILT |
309 | |
310 | case DEF * 16 + UNDEF: | |
311 | case WEAK_DEF * 16 + UNDEF: | |
312 | case DYN_DEF * 16 + UNDEF: | |
313 | case DYN_WEAK_DEF * 16 + UNDEF: | |
314 | case UNDEF * 16 + UNDEF: | |
315 | case WEAK_UNDEF * 16 + UNDEF: | |
316 | case DYN_UNDEF * 16 + UNDEF: | |
317 | case DYN_WEAK_UNDEF * 16 + UNDEF: | |
318 | case COMMON * 16 + UNDEF: | |
319 | case WEAK_COMMON * 16 + UNDEF: | |
320 | case DYN_COMMON * 16 + UNDEF: | |
321 | case DYN_WEAK_COMMON * 16 + UNDEF: | |
1564db8d ILT |
322 | // A new undefined reference tells us nothing. |
323 | return; | |
14bfc3f5 ILT |
324 | |
325 | case DEF * 16 + WEAK_UNDEF: | |
326 | case WEAK_DEF * 16 + WEAK_UNDEF: | |
327 | case DYN_DEF * 16 + WEAK_UNDEF: | |
328 | case DYN_WEAK_DEF * 16 + WEAK_UNDEF: | |
329 | case UNDEF * 16 + WEAK_UNDEF: | |
330 | case WEAK_UNDEF * 16 + WEAK_UNDEF: | |
331 | case DYN_UNDEF * 16 + WEAK_UNDEF: | |
332 | case DYN_WEAK_UNDEF * 16 + WEAK_UNDEF: | |
333 | case COMMON * 16 + WEAK_UNDEF: | |
334 | case WEAK_COMMON * 16 + WEAK_UNDEF: | |
335 | case DYN_COMMON * 16 + WEAK_UNDEF: | |
336 | case DYN_WEAK_COMMON * 16 + WEAK_UNDEF: | |
1564db8d ILT |
337 | // A new weak undefined reference tells us nothing. |
338 | return; | |
14bfc3f5 ILT |
339 | |
340 | case DEF * 16 + DYN_UNDEF: | |
341 | case WEAK_DEF * 16 + DYN_UNDEF: | |
342 | case DYN_DEF * 16 + DYN_UNDEF: | |
343 | case DYN_WEAK_DEF * 16 + DYN_UNDEF: | |
344 | case UNDEF * 16 + DYN_UNDEF: | |
345 | case WEAK_UNDEF * 16 + DYN_UNDEF: | |
346 | case DYN_UNDEF * 16 + DYN_UNDEF: | |
347 | case DYN_WEAK_UNDEF * 16 + DYN_UNDEF: | |
348 | case COMMON * 16 + DYN_UNDEF: | |
349 | case WEAK_COMMON * 16 + DYN_UNDEF: | |
350 | case DYN_COMMON * 16 + DYN_UNDEF: | |
351 | case DYN_WEAK_COMMON * 16 + DYN_UNDEF: | |
1564db8d ILT |
352 | // A new dynamic undefined reference tells us nothing. |
353 | return; | |
14bfc3f5 ILT |
354 | |
355 | case DEF * 16 + DYN_WEAK_UNDEF: | |
356 | case WEAK_DEF * 16 + DYN_WEAK_UNDEF: | |
357 | case DYN_DEF * 16 + DYN_WEAK_UNDEF: | |
358 | case DYN_WEAK_DEF * 16 + DYN_WEAK_UNDEF: | |
359 | case UNDEF * 16 + DYN_WEAK_UNDEF: | |
360 | case WEAK_UNDEF * 16 + DYN_WEAK_UNDEF: | |
361 | case DYN_UNDEF * 16 + DYN_WEAK_UNDEF: | |
362 | case DYN_WEAK_UNDEF * 16 + DYN_WEAK_UNDEF: | |
363 | case COMMON * 16 + DYN_WEAK_UNDEF: | |
364 | case WEAK_COMMON * 16 + DYN_WEAK_UNDEF: | |
365 | case DYN_COMMON * 16 + DYN_WEAK_UNDEF: | |
366 | case DYN_WEAK_COMMON * 16 + DYN_WEAK_UNDEF: | |
1564db8d ILT |
367 | // A new weak dynamic undefined reference tells us nothing. |
368 | return; | |
14bfc3f5 ILT |
369 | |
370 | case DEF * 16 + COMMON: | |
1564db8d ILT |
371 | // A common symbol does not override a definition. |
372 | return; | |
373 | ||
14bfc3f5 ILT |
374 | case WEAK_DEF * 16 + COMMON: |
375 | case DYN_DEF * 16 + COMMON: | |
376 | case DYN_WEAK_DEF * 16 + COMMON: | |
1564db8d ILT |
377 | // A common symbol does override a weak definition or a dynamic |
378 | // definition. | |
379 | to->override(sym, object); | |
380 | return; | |
381 | ||
14bfc3f5 ILT |
382 | case UNDEF * 16 + COMMON: |
383 | case WEAK_UNDEF * 16 + COMMON: | |
384 | case DYN_UNDEF * 16 + COMMON: | |
385 | case DYN_WEAK_UNDEF * 16 + COMMON: | |
1564db8d ILT |
386 | // A common symbol is a definition for a reference. |
387 | to->override(sym, object); | |
388 | return; | |
389 | ||
14bfc3f5 ILT |
390 | case COMMON * 16 + COMMON: |
391 | case WEAK_COMMON * 16 + COMMON: | |
392 | case DYN_COMMON * 16 + COMMON: | |
393 | case DYN_WEAK_COMMON * 16 + COMMON: | |
394 | ||
395 | case DEF * 16 + WEAK_COMMON: | |
396 | case WEAK_DEF * 16 + WEAK_COMMON: | |
397 | case DYN_DEF * 16 + WEAK_COMMON: | |
398 | case DYN_WEAK_DEF * 16 + WEAK_COMMON: | |
399 | case UNDEF * 16 + WEAK_COMMON: | |
400 | case WEAK_UNDEF * 16 + WEAK_COMMON: | |
401 | case DYN_UNDEF * 16 + WEAK_COMMON: | |
402 | case DYN_WEAK_UNDEF * 16 + WEAK_COMMON: | |
403 | case COMMON * 16 + WEAK_COMMON: | |
404 | case WEAK_COMMON * 16 + WEAK_COMMON: | |
405 | case DYN_COMMON * 16 + WEAK_COMMON: | |
406 | case DYN_WEAK_COMMON * 16 + WEAK_COMMON: | |
407 | ||
408 | case DEF * 16 + DYN_COMMON: | |
409 | case WEAK_DEF * 16 + DYN_COMMON: | |
410 | case DYN_DEF * 16 + DYN_COMMON: | |
411 | case DYN_WEAK_DEF * 16 + DYN_COMMON: | |
412 | case UNDEF * 16 + DYN_COMMON: | |
413 | case WEAK_UNDEF * 16 + DYN_COMMON: | |
414 | case DYN_UNDEF * 16 + DYN_COMMON: | |
415 | case DYN_WEAK_UNDEF * 16 + DYN_COMMON: | |
416 | case COMMON * 16 + DYN_COMMON: | |
417 | case WEAK_COMMON * 16 + DYN_COMMON: | |
418 | case DYN_COMMON * 16 + DYN_COMMON: | |
419 | case DYN_WEAK_COMMON * 16 + DYN_COMMON: | |
420 | ||
421 | case DEF * 16 + DYN_WEAK_COMMON: | |
422 | case WEAK_DEF * 16 + DYN_WEAK_COMMON: | |
423 | case DYN_DEF * 16 + DYN_WEAK_COMMON: | |
424 | case DYN_WEAK_DEF * 16 + DYN_WEAK_COMMON: | |
425 | case UNDEF * 16 + DYN_WEAK_COMMON: | |
426 | case WEAK_UNDEF * 16 + DYN_WEAK_COMMON: | |
427 | case DYN_UNDEF * 16 + DYN_WEAK_COMMON: | |
428 | case DYN_WEAK_UNDEF * 16 + DYN_WEAK_COMMON: | |
429 | case COMMON * 16 + DYN_WEAK_COMMON: | |
430 | case WEAK_COMMON * 16 + DYN_WEAK_COMMON: | |
431 | case DYN_COMMON * 16 + DYN_WEAK_COMMON: | |
432 | case DYN_WEAK_COMMON * 16 + DYN_WEAK_COMMON: | |
1564db8d | 433 | abort(); |
14bfc3f5 | 434 | break; |
1564db8d ILT |
435 | |
436 | default: | |
437 | abort(); | |
14bfc3f5 ILT |
438 | } |
439 | } | |
440 | ||
441 | // Instantiate the templates we need. We could use the configure | |
442 | // script to restrict this to only the ones needed for implemented | |
443 | // targets. | |
444 | ||
445 | template | |
446 | void | |
447 | Symbol_table::resolve<32, true>( | |
1564db8d | 448 | Sized_symbol<32>* to, |
14bfc3f5 ILT |
449 | const elfcpp::Sym<32, true>& sym, |
450 | Object* object); | |
451 | ||
452 | template | |
453 | void | |
454 | Symbol_table::resolve<32, false>( | |
1564db8d | 455 | Sized_symbol<32>* to, |
14bfc3f5 ILT |
456 | const elfcpp::Sym<32, false>& sym, |
457 | Object* object); | |
458 | ||
459 | template | |
460 | void | |
461 | Symbol_table::resolve<64, true>( | |
1564db8d | 462 | Sized_symbol<64>* to, |
14bfc3f5 ILT |
463 | const elfcpp::Sym<64, true>& sym, |
464 | Object* object); | |
465 | ||
466 | template | |
467 | void | |
468 | Symbol_table::resolve<64, false>( | |
1564db8d | 469 | Sized_symbol<64>* to, |
14bfc3f5 ILT |
470 | const elfcpp::Sym<64, false>& sym, |
471 | Object* object); | |
472 | ||
473 | } // End namespace gold. |