1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
|
// resolve.cc -- symbol resolution for gold
#include "gold.h"
#include "elfcpp.h"
#include "target.h"
#include "object.h"
#include "symtab.h"
namespace gold
{
// Resolve a symbol. This is called the second and subsequent times
// we see a symbol. TO is the pre-existing symbol. SYM is the new
// symbol, seen in OBJECT.
template<int size, bool big_endian>
void
Symbol_table::resolve(Symbol* to,
const elfcpp::Sym<size, big_endian>& sym,
Object* object)
{
if (object->target()->has_resolve())
{
object->sized_target<size, big_endian>()->resolve(to, sym, object);
return;
}
// Build a little code for each symbol.
// Bit 0: 0 for global, 1 for weak.
// Bit 1: 0 for regular object, 1 for shared object
// Bits 2-3: 0 for normal, 1 for undefined, 2 for common
// This gives us values from 0 to 11:
enum
{
DEF = 0,
WEAK_DEF = 1,
DYN_DEF = 2,
DYN_WEAK_DEF = 3,
UNDEF = 4,
WEAK_UNDEF = 5,
DYN_UNDEF = 6,
DYN_WEAK_UNDEF = 7,
COMMON = 8,
WEAK_COMMON = 9,
DYN_COMMON = 10,
DYN_WEAK_COMMON = 11
};
int tobits;
switch (to->binding())
{
case elfcpp::STB_GLOBAL:
tobits = 0;
break;
case elfcpp::STB_WEAK:
tobits = 1;
break;
case elfcpp::STB_LOCAL:
// We should only see externally visible symbols in the symbol
// table.
abort();
default:
// Any target which wants to handle STB_LOOS, etc., needs to
// define a resolve method.
abort();
}
if (to->object() != NULL && to->object()->is_dynamic())
tobits |= (1 << 1);
switch (to->shnum())
{
case elfcpp::SHN_UNDEF:
tobits |= (1 << 2);
break;
case elfcpp::SHN_COMMON:
tobits |= (2 << 2);
break;
default:
break;
}
int frombits;
switch (sym.get_st_bind())
{
case elfcpp::STB_GLOBAL:
frombits = 0;
break;
case elfcpp::STB_WEAK:
frombits = 1;
break;
case elfcpp::STB_LOCAL:
fprintf(stderr,
_("%s: %s: invalid STB_LOCAL symbol %s in external symbols\n"),
program_name, object->name().c_str(), to->name());
gold_exit(false);
default:
fprintf(stderr,
_("%s: %s: unsupported symbol binding %d for symbol %s\n"),
program_name, object->name().c_str(),
static_cast<int>(sym.get_st_bind()), to->name());
gold_exit(false);
}
if (object->is_dynamic())
frombits |= (1 << 1);
switch (sym.get_st_shndx())
{
case elfcpp::SHN_UNDEF:
frombits |= (1 << 2);
break;
case elfcpp::SHN_COMMON:
frombits |= (2 << 2);
break;
default:
break;
}
// We use a giant switch table for symbol resolution. This code is
// unwieldy, but: 1) it is efficient; 2) we definitely handle all
// cases; 3) it is easy to change the handling of a particular case.
// The alternative would be a series of conditionals, but it is easy
// to get the ordering wrong. This could also be done as a table,
// but that is no easier to understand than this large switch
// statement.
switch (tobits * 16 + frombits)
{
case DEF * 16 + DEF:
// Two definitions of the same symbol.
fprintf(stderr, "%s: %s: multiple definition of %s\n",
program_name, object->name().c_str(), to->name());
// FIXME: Report locations. Record that we have seen an error.
return;
case WEAK_DEF * 16 + DEF:
// In the original SVR4 linker, a weak definition followed by a
// regular definition was treated as a multiple definition
// error. In the Solaris linker and the GNU linker, a weak
// definition followed by a regular definition causes the
// regular definition to be ignored. We are currently
// compatible with the GNU linker. In the future we should add
// a target specific option to change this. FIXME.
return;
case DYN_DEF * 16 + DEF:
case DYN_WEAK_DEF * 16 + DEF:
case UNDEF * 16 + DEF:
case WEAK_UNDEF * 16 + DEF:
case DYN_UNDEF * 16 + DEF:
case DYN_WEAK_UNDEF * 16 + DEF:
case COMMON * 16 + DEF:
case WEAK_COMMON * 16 + DEF:
case DYN_COMMON * 16 + DEF:
case DYN_WEAK_COMMON * 16 + DEF:
case DEF * 16 + WEAK_DEF:
case WEAK_DEF * 16 + WEAK_DEF:
case DYN_DEF * 16 + WEAK_DEF:
case DYN_WEAK_DEF * 16 + WEAK_DEF:
case UNDEF * 16 + WEAK_DEF:
case WEAK_UNDEF * 16 + WEAK_DEF:
case DYN_UNDEF * 16 + WEAK_DEF:
case DYN_WEAK_UNDEF * 16 + WEAK_DEF:
case COMMON * 16 + WEAK_DEF:
case WEAK_COMMON * 16 + WEAK_DEF:
case DYN_COMMON * 16 + WEAK_DEF:
case DYN_WEAK_COMMON * 16 + WEAK_DEF:
case DEF * 16 + DYN_DEF:
case WEAK_DEF * 16 + DYN_DEF:
case DYN_DEF * 16 + DYN_DEF:
case DYN_WEAK_DEF * 16 + DYN_DEF:
case UNDEF * 16 + DYN_DEF:
case WEAK_UNDEF * 16 + DYN_DEF:
case DYN_UNDEF * 16 + DYN_DEF:
case DYN_WEAK_UNDEF * 16 + DYN_DEF:
case COMMON * 16 + DYN_DEF:
case WEAK_COMMON * 16 + DYN_DEF:
case DYN_COMMON * 16 + DYN_DEF:
case DYN_WEAK_COMMON * 16 + DYN_DEF:
case DEF * 16 + DYN_WEAK_DEF:
case WEAK_DEF * 16 + DYN_WEAK_DEF:
case DYN_DEF * 16 + DYN_WEAK_DEF:
case DYN_WEAK_DEF * 16 + DYN_WEAK_DEF:
case UNDEF * 16 + DYN_WEAK_DEF:
case WEAK_UNDEF * 16 + DYN_WEAK_DEF:
case DYN_UNDEF * 16 + DYN_WEAK_DEF:
case DYN_WEAK_UNDEF * 16 + DYN_WEAK_DEF:
case COMMON * 16 + DYN_WEAK_DEF:
case WEAK_COMMON * 16 + DYN_WEAK_DEF:
case DYN_COMMON * 16 + DYN_WEAK_DEF:
case DYN_WEAK_COMMON * 16 + DYN_WEAK_DEF:
case DEF * 16 + UNDEF:
case WEAK_DEF * 16 + UNDEF:
case DYN_DEF * 16 + UNDEF:
case DYN_WEAK_DEF * 16 + UNDEF:
case UNDEF * 16 + UNDEF:
case WEAK_UNDEF * 16 + UNDEF:
case DYN_UNDEF * 16 + UNDEF:
case DYN_WEAK_UNDEF * 16 + UNDEF:
case COMMON * 16 + UNDEF:
case WEAK_COMMON * 16 + UNDEF:
case DYN_COMMON * 16 + UNDEF:
case DYN_WEAK_COMMON * 16 + UNDEF:
case DEF * 16 + WEAK_UNDEF:
case WEAK_DEF * 16 + WEAK_UNDEF:
case DYN_DEF * 16 + WEAK_UNDEF:
case DYN_WEAK_DEF * 16 + WEAK_UNDEF:
case UNDEF * 16 + WEAK_UNDEF:
case WEAK_UNDEF * 16 + WEAK_UNDEF:
case DYN_UNDEF * 16 + WEAK_UNDEF:
case DYN_WEAK_UNDEF * 16 + WEAK_UNDEF:
case COMMON * 16 + WEAK_UNDEF:
case WEAK_COMMON * 16 + WEAK_UNDEF:
case DYN_COMMON * 16 + WEAK_UNDEF:
case DYN_WEAK_COMMON * 16 + WEAK_UNDEF:
case DEF * 16 + DYN_UNDEF:
case WEAK_DEF * 16 + DYN_UNDEF:
case DYN_DEF * 16 + DYN_UNDEF:
case DYN_WEAK_DEF * 16 + DYN_UNDEF:
case UNDEF * 16 + DYN_UNDEF:
case WEAK_UNDEF * 16 + DYN_UNDEF:
case DYN_UNDEF * 16 + DYN_UNDEF:
case DYN_WEAK_UNDEF * 16 + DYN_UNDEF:
case COMMON * 16 + DYN_UNDEF:
case WEAK_COMMON * 16 + DYN_UNDEF:
case DYN_COMMON * 16 + DYN_UNDEF:
case DYN_WEAK_COMMON * 16 + DYN_UNDEF:
case DEF * 16 + DYN_WEAK_UNDEF:
case WEAK_DEF * 16 + DYN_WEAK_UNDEF:
case DYN_DEF * 16 + DYN_WEAK_UNDEF:
case DYN_WEAK_DEF * 16 + DYN_WEAK_UNDEF:
case UNDEF * 16 + DYN_WEAK_UNDEF:
case WEAK_UNDEF * 16 + DYN_WEAK_UNDEF:
case DYN_UNDEF * 16 + DYN_WEAK_UNDEF:
case DYN_WEAK_UNDEF * 16 + DYN_WEAK_UNDEF:
case COMMON * 16 + DYN_WEAK_UNDEF:
case WEAK_COMMON * 16 + DYN_WEAK_UNDEF:
case DYN_COMMON * 16 + DYN_WEAK_UNDEF:
case DYN_WEAK_COMMON * 16 + DYN_WEAK_UNDEF:
case DEF * 16 + COMMON:
case WEAK_DEF * 16 + COMMON:
case DYN_DEF * 16 + COMMON:
case DYN_WEAK_DEF * 16 + COMMON:
case UNDEF * 16 + COMMON:
case WEAK_UNDEF * 16 + COMMON:
case DYN_UNDEF * 16 + COMMON:
case DYN_WEAK_UNDEF * 16 + COMMON:
case COMMON * 16 + COMMON:
case WEAK_COMMON * 16 + COMMON:
case DYN_COMMON * 16 + COMMON:
case DYN_WEAK_COMMON * 16 + COMMON:
case DEF * 16 + WEAK_COMMON:
case WEAK_DEF * 16 + WEAK_COMMON:
case DYN_DEF * 16 + WEAK_COMMON:
case DYN_WEAK_DEF * 16 + WEAK_COMMON:
case UNDEF * 16 + WEAK_COMMON:
case WEAK_UNDEF * 16 + WEAK_COMMON:
case DYN_UNDEF * 16 + WEAK_COMMON:
case DYN_WEAK_UNDEF * 16 + WEAK_COMMON:
case COMMON * 16 + WEAK_COMMON:
case WEAK_COMMON * 16 + WEAK_COMMON:
case DYN_COMMON * 16 + WEAK_COMMON:
case DYN_WEAK_COMMON * 16 + WEAK_COMMON:
case DEF * 16 + DYN_COMMON:
case WEAK_DEF * 16 + DYN_COMMON:
case DYN_DEF * 16 + DYN_COMMON:
case DYN_WEAK_DEF * 16 + DYN_COMMON:
case UNDEF * 16 + DYN_COMMON:
case WEAK_UNDEF * 16 + DYN_COMMON:
case DYN_UNDEF * 16 + DYN_COMMON:
case DYN_WEAK_UNDEF * 16 + DYN_COMMON:
case COMMON * 16 + DYN_COMMON:
case WEAK_COMMON * 16 + DYN_COMMON:
case DYN_COMMON * 16 + DYN_COMMON:
case DYN_WEAK_COMMON * 16 + DYN_COMMON:
case DEF * 16 + DYN_WEAK_COMMON:
case WEAK_DEF * 16 + DYN_WEAK_COMMON:
case DYN_DEF * 16 + DYN_WEAK_COMMON:
case DYN_WEAK_DEF * 16 + DYN_WEAK_COMMON:
case UNDEF * 16 + DYN_WEAK_COMMON:
case WEAK_UNDEF * 16 + DYN_WEAK_COMMON:
case DYN_UNDEF * 16 + DYN_WEAK_COMMON:
case DYN_WEAK_UNDEF * 16 + DYN_WEAK_COMMON:
case COMMON * 16 + DYN_WEAK_COMMON:
case WEAK_COMMON * 16 + DYN_WEAK_COMMON:
case DYN_COMMON * 16 + DYN_WEAK_COMMON:
case DYN_WEAK_COMMON * 16 + DYN_WEAK_COMMON:
break;
}
}
// Instantiate the templates we need. We could use the configure
// script to restrict this to only the ones needed for implemented
// targets.
template
void
Symbol_table::resolve<32, true>(
Symbol* to,
const elfcpp::Sym<32, true>& sym,
Object* object);
template
void
Symbol_table::resolve<32, false>(
Symbol* to,
const elfcpp::Sym<32, false>& sym,
Object* object);
template
void
Symbol_table::resolve<64, true>(
Symbol* to,
const elfcpp::Sym<64, true>& sym,
Object* object);
template
void
Symbol_table::resolve<64, false>(
Symbol* to,
const elfcpp::Sym<64, false>& sym,
Object* object);
} // End namespace gold.
|
