-
Notifications
You must be signed in to change notification settings - Fork 14
/
Copy pathtccelf.c
2893 lines (2627 loc) · 92.3 KB
/
tccelf.c
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
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
/*
* ELF file handling for TCC
*
* Copyright (c) 2001-2004 Fabrice Bellard
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "tcc.h"
/* Define this to get some debug output during relocation processing. */
#undef DEBUG_RELOC
/********************************************************/
/* global variables */
ST_DATA Section *text_section, *data_section, *bss_section; /* predefined sections */
ST_DATA Section *cur_text_section; /* current section where function code is generated */
#ifdef CONFIG_TCC_ASM
ST_DATA Section *last_text_section; /* to handle .previous asm directive */
#endif
#ifdef CONFIG_TCC_BCHECK
/* bound check related sections */
ST_DATA Section *bounds_section; /* contains global data bound description */
ST_DATA Section *lbounds_section; /* contains local data bound description */
#endif
/* symbol sections */
ST_DATA Section *symtab_section, *strtab_section;
/* debug sections */
ST_DATA Section *stab_section, *stabstr_section;
/* XXX: avoid static variable */
static int new_undef_sym = 0; /* Is there a new undefined sym since last new_undef_sym() */
/* ------------------------------------------------------------------------- */
ST_FUNC void tccelf_new(TCCState *s)
{
/* no section zero */
dynarray_add((void ***)&s->sections, &s->nb_sections, NULL);
/* create standard sections */
text_section = new_section(s, ".text", SHT_PROGBITS, SHF_ALLOC | SHF_EXECINSTR);
data_section = new_section(s, ".data", SHT_PROGBITS, SHF_ALLOC | SHF_WRITE);
bss_section = new_section(s, ".bss", SHT_NOBITS, SHF_ALLOC | SHF_WRITE);
/* symbols are always generated for linking stage */
symtab_section = new_symtab(s, ".symtab", SHT_SYMTAB, 0,
".strtab",
".hashtab", SHF_PRIVATE);
strtab_section = symtab_section->link;
s->symtab = symtab_section;
/* private symbol table for dynamic symbols */
s->dynsymtab_section = new_symtab(s, ".dynsymtab", SHT_SYMTAB, SHF_PRIVATE,
".dynstrtab",
".dynhashtab", SHF_PRIVATE);
get_sym_attr(s, 0, 1);
}
#ifdef CONFIG_TCC_BCHECK
ST_FUNC void tccelf_bounds_new(TCCState *s)
{
/* create bounds sections */
bounds_section = new_section(s, ".bounds",
SHT_PROGBITS, SHF_ALLOC);
lbounds_section = new_section(s, ".lbounds",
SHT_PROGBITS, SHF_ALLOC);
}
#endif
ST_FUNC void tccelf_stab_new(TCCState *s)
{
stab_section = new_section(s, ".stab", SHT_PROGBITS, 0);
stab_section->sh_entsize = sizeof(Stab_Sym);
stabstr_section = new_section(s, ".stabstr", SHT_STRTAB, 0);
put_elf_str(stabstr_section, "");
stab_section->link = stabstr_section;
/* put first entry */
put_stabs("", 0, 0, 0, 0);
}
static void free_section(Section *s)
{
tcc_free(s->data);
}
ST_FUNC void tccelf_delete(TCCState *s1)
{
int i;
/* free all sections */
for(i = 1; i < s1->nb_sections; i++)
free_section(s1->sections[i]);
dynarray_reset(&s1->sections, &s1->nb_sections);
for(i = 0; i < s1->nb_priv_sections; i++)
free_section(s1->priv_sections[i]);
dynarray_reset(&s1->priv_sections, &s1->nb_priv_sections);
/* free any loaded DLLs */
#ifdef TCC_IS_NATIVE
for ( i = 0; i < s1->nb_loaded_dlls; i++) {
DLLReference *ref = s1->loaded_dlls[i];
if ( ref->handle )
# ifdef _WIN32
FreeLibrary((HMODULE)ref->handle);
# else
dlclose(ref->handle);
# endif
}
#endif
/* free loaded dlls array */
dynarray_reset(&s1->loaded_dlls, &s1->nb_loaded_dlls);
tcc_free(s1->sym_attrs);
}
ST_FUNC Section *new_section(TCCState *s1, const char *name, int sh_type, int sh_flags)
{
Section *sec;
sec = tcc_mallocz(sizeof(Section) + strlen(name));
strcpy(sec->name, name);
sec->sh_type = sh_type;
sec->sh_flags = sh_flags;
switch(sh_type) {
case SHT_HASH:
case SHT_REL:
case SHT_RELA:
case SHT_DYNSYM:
case SHT_SYMTAB:
case SHT_DYNAMIC:
sec->sh_addralign = 4;
break;
case SHT_STRTAB:
sec->sh_addralign = 1;
break;
default:
sec->sh_addralign = PTR_SIZE; /* gcc/pcc default aligment */
break;
}
if (sh_flags & SHF_PRIVATE) {
dynarray_add((void ***)&s1->priv_sections, &s1->nb_priv_sections, sec);
} else {
sec->sh_num = s1->nb_sections;
dynarray_add((void ***)&s1->sections, &s1->nb_sections, sec);
}
return sec;
}
ST_FUNC Section *new_symtab(TCCState *s1,
const char *symtab_name, int sh_type, int sh_flags,
const char *strtab_name,
const char *hash_name, int hash_sh_flags)
{
Section *symtab, *strtab, *hash;
int *ptr, nb_buckets;
symtab = new_section(s1, symtab_name, sh_type, sh_flags);
symtab->sh_entsize = sizeof(ElfW(Sym));
strtab = new_section(s1, strtab_name, SHT_STRTAB, sh_flags);
put_elf_str(strtab, "");
symtab->link = strtab;
put_elf_sym(symtab, 0, 0, 0, 0, 0, NULL);
nb_buckets = 1;
hash = new_section(s1, hash_name, SHT_HASH, hash_sh_flags);
hash->sh_entsize = sizeof(int);
symtab->hash = hash;
hash->link = symtab;
ptr = section_ptr_add(hash, (2 + nb_buckets + 1) * sizeof(int));
ptr[0] = nb_buckets;
ptr[1] = 1;
memset(ptr + 2, 0, (nb_buckets + 1) * sizeof(int));
return symtab;
}
/* realloc section and set its content to zero */
ST_FUNC void section_realloc(Section *sec, unsigned long new_size)
{
unsigned long size;
unsigned char *data;
size = sec->data_allocated;
if (size == 0)
size = 1;
while (size < new_size)
size = size * 2;
data = tcc_realloc(sec->data, size);
memset(data + sec->data_allocated, 0, size - sec->data_allocated);
sec->data = data;
sec->data_allocated = size;
}
/* reserve at least 'size' bytes in section 'sec' from
sec->data_offset. */
ST_FUNC void *section_ptr_add(Section *sec, addr_t size)
{
size_t offset, offset1;
offset = sec->data_offset;
offset1 = offset + size;
if (offset1 > sec->data_allocated)
section_realloc(sec, offset1);
sec->data_offset = offset1;
return sec->data + offset;
}
/* reserve at least 'size' bytes from section start */
ST_FUNC void section_reserve(Section *sec, unsigned long size)
{
if (size > sec->data_allocated)
section_realloc(sec, size);
if (size > sec->data_offset)
sec->data_offset = size;
}
/* return a reference to a section, and create it if it does not
exists */
ST_FUNC Section *find_section(TCCState *s1, const char *name)
{
Section *sec;
int i;
for(i = 1; i < s1->nb_sections; i++) {
sec = s1->sections[i];
if (!strcmp(name, sec->name))
return sec;
}
/* sections are created as PROGBITS */
return new_section(s1, name, SHT_PROGBITS, SHF_ALLOC);
}
/* ------------------------------------------------------------------------- */
ST_FUNC int put_elf_str(Section *s, const char *sym)
{
int offset, len;
char *ptr;
len = strlen(sym) + 1;
offset = s->data_offset;
ptr = section_ptr_add(s, len);
memcpy(ptr, sym, len);
return offset;
}
/* elf symbol hashing function */
static unsigned long elf_hash(const unsigned char *name)
{
unsigned long h = 0, g;
while (*name) {
h = (h << 4) + *name++;
g = h & 0xf0000000;
if (g)
h ^= g >> 24;
h &= ~g;
}
return h;
}
/* rebuild hash table of section s */
/* NOTE: we do factorize the hash table code to go faster */
static void rebuild_hash(Section *s, unsigned int nb_buckets)
{
ElfW(Sym) *sym;
int *ptr, *hash, nb_syms, sym_index, h;
unsigned char *strtab;
strtab = s->link->data;
nb_syms = s->data_offset / sizeof(ElfW(Sym));
s->hash->data_offset = 0;
ptr = section_ptr_add(s->hash, (2 + nb_buckets + nb_syms) * sizeof(int));
ptr[0] = nb_buckets;
ptr[1] = nb_syms;
ptr += 2;
hash = ptr;
memset(hash, 0, (nb_buckets + 1) * sizeof(int));
ptr += nb_buckets + 1;
sym = (ElfW(Sym) *)s->data + 1;
for(sym_index = 1; sym_index < nb_syms; sym_index++) {
if (ELFW(ST_BIND)(sym->st_info) != STB_LOCAL) {
h = elf_hash(strtab + sym->st_name) % nb_buckets;
*ptr = hash[h];
hash[h] = sym_index;
} else {
*ptr = 0;
}
ptr++;
sym++;
}
}
/* return the symbol number */
ST_FUNC int put_elf_sym(Section *s, addr_t value, unsigned long size,
int info, int other, int shndx, const char *name)
{
int name_offset, sym_index;
int nbuckets, h;
ElfW(Sym) *sym;
Section *hs;
sym = section_ptr_add(s, sizeof(ElfW(Sym)));
if (name)
name_offset = put_elf_str(s->link, name);
else
name_offset = 0;
/* XXX: endianness */
sym->st_name = name_offset;
sym->st_value = value;
sym->st_size = size;
sym->st_info = info;
sym->st_other = other;
sym->st_shndx = shndx;
sym_index = sym - (ElfW(Sym) *)s->data;
hs = s->hash;
if (hs) {
int *ptr, *base;
ptr = section_ptr_add(hs, sizeof(int));
base = (int *)hs->data;
/* only add global or weak symbols */
if (ELFW(ST_BIND)(info) != STB_LOCAL) {
/* add another hashing entry */
nbuckets = base[0];
h = elf_hash((unsigned char *) name) % nbuckets;
*ptr = base[2 + h];
base[2 + h] = sym_index;
base[1]++;
/* we resize the hash table */
hs->nb_hashed_syms++;
if (hs->nb_hashed_syms > 2 * nbuckets) {
rebuild_hash(s, 2 * nbuckets);
}
} else {
*ptr = 0;
base[1]++;
}
}
return sym_index;
}
/* find global ELF symbol 'name' and return its index. Return 0 if not
found. */
ST_FUNC int find_elf_sym(Section *s, const char *name)
{
ElfW(Sym) *sym;
Section *hs;
int nbuckets, sym_index, h;
const char *name1;
hs = s->hash;
if (!hs)
return 0;
nbuckets = ((int *)hs->data)[0];
h = elf_hash((unsigned char *) name) % nbuckets;
sym_index = ((int *)hs->data)[2 + h];
while (sym_index != 0) {
sym = &((ElfW(Sym) *)s->data)[sym_index];
name1 = (char *) s->link->data + sym->st_name;
if (!strcmp(name, name1))
return sym_index;
sym_index = ((int *)hs->data)[2 + nbuckets + sym_index];
}
return 0;
}
/* return elf symbol value, signal error if 'err' is nonzero */
ST_FUNC addr_t get_elf_sym_addr(TCCState *s, const char *name, int err)
{
int sym_index;
ElfW(Sym) *sym;
sym_index = find_elf_sym(s->symtab, name);
sym = &((ElfW(Sym) *)s->symtab->data)[sym_index];
if (!sym_index || sym->st_shndx == SHN_UNDEF) {
if (err)
tcc_error("%s not defined", name);
return 0;
}
return sym->st_value;
}
/* return elf symbol value */
LIBTCCAPI void *tcc_get_symbol(TCCState *s, const char *name)
{
return (void*)(uintptr_t)get_elf_sym_addr(s, name, 0);
}
#if defined TCC_IS_NATIVE || defined TCC_TARGET_PE
/* return elf symbol value or error */
ST_FUNC void* tcc_get_symbol_err(TCCState *s, const char *name)
{
return (void*)(uintptr_t)get_elf_sym_addr(s, name, 1);
}
#endif
/* add an elf symbol : check if it is already defined and patch
it. Return symbol index. NOTE that sh_num can be SHN_UNDEF. */
ST_FUNC int set_elf_sym(Section *s, addr_t value, unsigned long size,
int info, int other, int shndx, const char *name)
{
ElfW(Sym) *esym;
int sym_bind, sym_index, sym_type, esym_bind;
unsigned char sym_vis, esym_vis, new_vis;
sym_bind = ELFW(ST_BIND)(info);
sym_type = ELFW(ST_TYPE)(info);
sym_vis = ELFW(ST_VISIBILITY)(other);
sym_index = find_elf_sym(s, name);
esym = &((ElfW(Sym) *)s->data)[sym_index];
if (sym_index && esym->st_value == value && esym->st_size == size
&& esym->st_info == info && esym->st_other == other
&& esym->st_shndx == shndx)
return sym_index;
if (sym_bind != STB_LOCAL) {
/* we search global or weak symbols */
if (!sym_index)
goto do_def;
if (esym->st_shndx != SHN_UNDEF) {
esym_bind = ELFW(ST_BIND)(esym->st_info);
/* propagate the most constraining visibility */
/* STV_DEFAULT(0)<STV_PROTECTED(3)<STV_HIDDEN(2)<STV_INTERNAL(1) */
esym_vis = ELFW(ST_VISIBILITY)(esym->st_other);
if (esym_vis == STV_DEFAULT) {
new_vis = sym_vis;
} else if (sym_vis == STV_DEFAULT) {
new_vis = esym_vis;
} else {
new_vis = (esym_vis < sym_vis) ? esym_vis : sym_vis;
}
esym->st_other = (esym->st_other & ~ELFW(ST_VISIBILITY)(-1))
| new_vis;
other = esym->st_other; /* in case we have to patch esym */
if (shndx == SHN_UNDEF) {
/* ignore adding of undefined symbol if the
corresponding symbol is already defined */
} else if (sym_bind == STB_GLOBAL && esym_bind == STB_WEAK) {
/* global overrides weak, so patch */
goto do_patch;
} else if (sym_bind == STB_WEAK && esym_bind == STB_GLOBAL) {
/* weak is ignored if already global */
} else if (sym_bind == STB_WEAK && esym_bind == STB_WEAK) {
/* keep first-found weak definition, ignore subsequents */
} else if (sym_vis == STV_HIDDEN || sym_vis == STV_INTERNAL) {
/* ignore hidden symbols after */
} else if ((esym->st_shndx == SHN_COMMON
|| esym->st_shndx == bss_section->sh_num)
&& (shndx < SHN_LORESERVE
&& shndx != bss_section->sh_num)) {
/* data symbol gets precedence over common/bss */
goto do_patch;
} else if (shndx == SHN_COMMON || shndx == bss_section->sh_num) {
/* data symbol keeps precedence over common/bss */
} else if (s == tcc_state->dynsymtab_section) {
/* we accept that two DLL define the same symbol */
} else {
#if 0
printf("new_bind=%x new_shndx=%x new_vis=%x old_bind=%x old_shndx=%x old_vis=%x\n",
sym_bind, shndx, new_vis, esym_bind, esym->st_shndx, esym_vis);
#endif
tcc_error_noabort("'%s' defined twice", name);
}
} else {
do_patch:
esym->st_info = ELFW(ST_INFO)(sym_bind, sym_type);
esym->st_shndx = shndx;
new_undef_sym = 1;
esym->st_value = value;
esym->st_size = size;
esym->st_other = other;
}
} else {
do_def:
sym_index = put_elf_sym(s, value, size,
ELFW(ST_INFO)(sym_bind, sym_type), other,
shndx, name);
}
return sym_index;
}
/* put relocation */
ST_FUNC void put_elf_reloca(Section *symtab, Section *s, unsigned long offset,
int type, int symbol, addr_t addend)
{
char buf[256];
Section *sr;
ElfW_Rel *rel;
sr = s->reloc;
if (!sr) {
/* if no relocation section, create it */
snprintf(buf, sizeof(buf), REL_SECTION_FMT, s->name);
/* if the symtab is allocated, then we consider the relocation
are also */
sr = new_section(tcc_state, buf, SHT_RELX, symtab->sh_flags);
sr->sh_entsize = sizeof(ElfW_Rel);
sr->link = symtab;
sr->sh_info = s->sh_num;
s->reloc = sr;
}
rel = section_ptr_add(sr, sizeof(ElfW_Rel));
rel->r_offset = offset;
rel->r_info = ELFW(R_INFO)(symbol, type);
#if SHT_RELX == SHT_RELA
rel->r_addend = addend;
#else
if (addend)
tcc_error("non-zero addend on REL architecture");
#endif
}
ST_FUNC void put_elf_reloc(Section *symtab, Section *s, unsigned long offset,
int type, int symbol)
{
put_elf_reloca(symtab, s, offset, type, symbol, 0);
}
/* Remove relocations for section S->reloc starting at oldrelocoffset
that are to the same place, retaining the last of them. As side effect
the relocations are sorted. Possibly reduces the number of relocs. */
ST_FUNC void squeeze_multi_relocs(Section *s, size_t oldrelocoffset)
{
Section *sr = s->reloc;
ElfW_Rel *r, *dest;
ssize_t a;
ElfW(Addr) addr;
if (oldrelocoffset + sizeof(*r) >= sr->data_offset)
return;
/* The relocs we're dealing with are the result of initializer parsing.
So they will be mostly in order and there aren't many of them.
Secondly we need a stable sort (which qsort isn't). We use
a simple insertion sort. */
for (a = oldrelocoffset + sizeof(*r); a < sr->data_offset; a += sizeof(*r)) {
ssize_t i = a - sizeof(*r);
addr = ((ElfW_Rel*)(sr->data + a))->r_offset;
for (; i >= (ssize_t)oldrelocoffset &&
((ElfW_Rel*)(sr->data + i))->r_offset > addr; i -= sizeof(*r)) {
ElfW_Rel tmp = *(ElfW_Rel*)(sr->data + a);
*(ElfW_Rel*)(sr->data + a) = *(ElfW_Rel*)(sr->data + i);
*(ElfW_Rel*)(sr->data + i) = tmp;
}
}
r = (ElfW_Rel*)(sr->data + oldrelocoffset);
dest = r;
for (; r < (ElfW_Rel*)(sr->data + sr->data_offset); r++) {
if (dest->r_offset != r->r_offset)
dest++;
*dest = *r;
}
sr->data_offset = (unsigned char*)dest - sr->data + sizeof(*r);
}
/* put stab debug information */
ST_FUNC void put_stabs(const char *str, int type, int other, int desc,
unsigned long value)
{
Stab_Sym *sym;
sym = section_ptr_add(stab_section, sizeof(Stab_Sym));
if (str) {
sym->n_strx = put_elf_str(stabstr_section, str);
} else {
sym->n_strx = 0;
}
sym->n_type = type;
sym->n_other = other;
sym->n_desc = desc;
sym->n_value = value;
}
ST_FUNC void put_stabs_r(const char *str, int type, int other, int desc,
unsigned long value, Section *sec, int sym_index)
{
put_stabs(str, type, other, desc, value);
put_elf_reloc(symtab_section, stab_section,
stab_section->data_offset - sizeof(unsigned int),
R_DATA_32, sym_index);
}
ST_FUNC void put_stabn(int type, int other, int desc, int value)
{
put_stabs(NULL, type, other, desc, value);
}
ST_FUNC void put_stabd(int type, int other, int desc)
{
put_stabs(NULL, type, other, desc, 0);
}
ST_FUNC struct sym_attr *get_sym_attr(TCCState *s1, int index, int alloc)
{
int n;
struct sym_attr *tab;
if (index >= s1->nb_sym_attrs) {
if (!alloc)
return s1->sym_attrs;
/* find immediately bigger power of 2 and reallocate array */
n = 1;
while (index >= n)
n *= 2;
tab = tcc_realloc(s1->sym_attrs, n * sizeof(*s1->sym_attrs));
s1->sym_attrs = tab;
memset(s1->sym_attrs + s1->nb_sym_attrs, 0,
(n - s1->nb_sym_attrs) * sizeof(*s1->sym_attrs));
s1->nb_sym_attrs = n;
}
return &s1->sym_attrs[index];
}
/* Browse each elem of type <type> in section <sec> starting at elem <startoff>
using variable <elem> */
#define for_each_elem(sec, startoff, elem, type) \
for (elem = (type *) sec->data + startoff; \
elem < (type *) (sec->data + sec->data_offset); elem++)
/* In an ELF file symbol table, the local symbols must appear below
the global and weak ones. Since TCC cannot sort it while generating
the code, we must do it after. All the relocation tables are also
modified to take into account the symbol table sorting */
static void sort_syms(TCCState *s1, Section *s)
{
int *old_to_new_syms;
ElfW(Sym) *new_syms;
int nb_syms, i;
ElfW(Sym) *p, *q;
ElfW_Rel *rel;
Section *sr;
int type, sym_index;
nb_syms = s->data_offset / sizeof(ElfW(Sym));
new_syms = tcc_malloc(nb_syms * sizeof(ElfW(Sym)));
old_to_new_syms = tcc_malloc(nb_syms * sizeof(int));
/* first pass for local symbols */
p = (ElfW(Sym) *)s->data;
q = new_syms;
for(i = 0; i < nb_syms; i++) {
if (ELFW(ST_BIND)(p->st_info) == STB_LOCAL) {
old_to_new_syms[i] = q - new_syms;
*q++ = *p;
}
p++;
}
/* save the number of local symbols in section header */
s->sh_info = q - new_syms;
/* then second pass for non local symbols */
p = (ElfW(Sym) *)s->data;
for(i = 0; i < nb_syms; i++) {
if (ELFW(ST_BIND)(p->st_info) != STB_LOCAL) {
old_to_new_syms[i] = q - new_syms;
*q++ = *p;
}
p++;
}
/* we copy the new symbols to the old */
memcpy(s->data, new_syms, nb_syms * sizeof(ElfW(Sym)));
tcc_free(new_syms);
/* now we modify all the relocations */
for(i = 1; i < s1->nb_sections; i++) {
sr = s1->sections[i];
if (sr->sh_type == SHT_RELX && sr->link == s) {
for_each_elem(sr, 0, rel, ElfW_Rel) {
sym_index = ELFW(R_SYM)(rel->r_info);
type = ELFW(R_TYPE)(rel->r_info);
sym_index = old_to_new_syms[sym_index];
rel->r_info = ELFW(R_INFO)(sym_index, type);
}
}
}
tcc_free(old_to_new_syms);
}
/* relocate common symbols in the .bss section */
ST_FUNC void relocate_common_syms(void)
{
ElfW(Sym) *sym;
unsigned long offset, align;
for_each_elem(symtab_section, 1, sym, ElfW(Sym)) {
if (sym->st_shndx == SHN_COMMON) {
/* align symbol */
align = sym->st_value;
offset = bss_section->data_offset;
offset = (offset + align - 1) & -align;
sym->st_value = offset;
sym->st_shndx = bss_section->sh_num;
offset += sym->st_size;
bss_section->data_offset = offset;
}
}
}
/* relocate symbol table, resolve undefined symbols if do_resolve is
true and output error if undefined symbol. */
ST_FUNC void relocate_syms(TCCState *s1, Section *symtab, int do_resolve)
{
ElfW(Sym) *sym;
int sym_bind, sh_num;
const char *name;
for_each_elem(symtab, 1, sym, ElfW(Sym)) {
sh_num = sym->st_shndx;
if (sh_num == SHN_UNDEF) {
name = (char *) strtab_section->data + sym->st_name;
/* Use ld.so to resolve symbol for us (for tcc -run) */
if (do_resolve) {
#if defined TCC_IS_NATIVE && !defined TCC_TARGET_PE
void *addr = dlsym(RTLD_DEFAULT, name);
if (addr) {
sym->st_value = (addr_t) addr;
#ifdef DEBUG_RELOC
printf ("relocate_sym: %s -> 0x%lx\n", name, sym->st_value);
#endif
goto found;
}
#endif
/* if dynamic symbol exist, it will be used in relocate_section */
} else if (s1->dynsym && find_elf_sym(s1->dynsym, name))
goto found;
/* XXX: _fp_hw seems to be part of the ABI, so we ignore
it */
if (!strcmp(name, "_fp_hw"))
goto found;
/* only weak symbols are accepted to be undefined. Their
value is zero */
sym_bind = ELFW(ST_BIND)(sym->st_info);
if (sym_bind == STB_WEAK)
sym->st_value = 0;
else
tcc_error_noabort("undefined symbol '%s'", name);
} else if (sh_num < SHN_LORESERVE) {
/* add section base */
sym->st_value += s1->sections[sym->st_shndx]->sh_addr;
}
found: ;
}
}
/* relocate a given section (CPU dependent) by applying the relocations
in the associated relocation section */
ST_FUNC void relocate_section(TCCState *s1, Section *s)
{
Section *sr = s->reloc;
ElfW_Rel *rel;
ElfW(Sym) *sym;
int type, sym_index;
unsigned char *ptr;
addr_t tgt, addr;
relocate_init(sr);
for_each_elem(sr, 0, rel, ElfW_Rel) {
ptr = s->data + rel->r_offset;
sym_index = ELFW(R_SYM)(rel->r_info);
sym = &((ElfW(Sym) *)symtab_section->data)[sym_index];
type = ELFW(R_TYPE)(rel->r_info);
tgt = sym->st_value;
#if SHT_RELX == SHT_RELA
tgt += rel->r_addend;
#endif
addr = s->sh_addr + rel->r_offset;
relocate(s1, rel, type, ptr, addr, tgt);
}
/* if the relocation is allocated, we change its symbol table */
if (sr->sh_flags & SHF_ALLOC)
sr->link = s1->dynsym;
}
/* relocate relocation table in 'sr' */
static void relocate_rel(TCCState *s1, Section *sr)
{
Section *s;
ElfW_Rel *rel;
s = s1->sections[sr->sh_info];
for_each_elem(sr, 0, rel, ElfW_Rel)
rel->r_offset += s->sh_addr;
}
/* count the number of dynamic relocations so that we can reserve
their space */
static int prepare_dynamic_rel(TCCState *s1, Section *sr)
{
ElfW_Rel *rel;
int sym_index, type, count;
count = 0;
for_each_elem(sr, 0, rel, ElfW_Rel) {
sym_index = ELFW(R_SYM)(rel->r_info);
type = ELFW(R_TYPE)(rel->r_info);
switch(type) {
#if defined(TCC_TARGET_I386)
case R_386_32:
#elif defined(TCC_TARGET_X86_64)
case R_X86_64_32:
case R_X86_64_32S:
case R_X86_64_64:
#endif
count++;
break;
#if defined(TCC_TARGET_I386)
case R_386_PC32:
#elif defined(TCC_TARGET_X86_64)
case R_X86_64_PC32:
#endif
if (get_sym_attr(s1, sym_index, 0)->dyn_index)
count++;
break;
default:
break;
}
}
if (count) {
/* allocate the section */
sr->sh_flags |= SHF_ALLOC;
sr->sh_size = count * sizeof(ElfW_Rel);
}
return count;
}
static void build_got(TCCState *s1)
{
/* if no got, then create it */
s1->got = new_section(s1, ".got", SHT_PROGBITS, SHF_ALLOC | SHF_WRITE);
s1->got->sh_entsize = 4;
set_elf_sym(symtab_section, 0, 4, ELFW(ST_INFO)(STB_GLOBAL, STT_OBJECT),
0, s1->got->sh_num, "_GLOBAL_OFFSET_TABLE_");
/* keep space for _DYNAMIC pointer and two dummy got entries */
section_ptr_add(s1->got, 3 * PTR_SIZE);
}
/* Create a GOT and (for function call) a PLT entry corresponding to a symbol
in s1->symtab. When creating the dynamic symbol table entry for the GOT
relocation, use 'size' and 'info' for the corresponding symbol metadata.
Returns the offset of the GOT or (if any) PLT entry. */
static struct sym_attr * put_got_entry(TCCState *s1, int dyn_reloc_type,
int reloc_type, unsigned long size,
int info, int sym_index)
{
int need_plt_entry;
const char *name;
ElfW(Sym) *sym;
struct sym_attr *attr;
unsigned got_offset;
char plt_name[100];
int len;
need_plt_entry = (dyn_reloc_type == R_JMP_SLOT);
attr = get_sym_attr(s1, sym_index, 1);
/* In case a function is both called and its address taken 2 GOT entries
are created, one for taking the address (GOT) and the other for the PLT
entry (PLTGOT). */
if (need_plt_entry ? attr->plt_offset : attr->got_offset)
return attr;
/* create the GOT entry */
got_offset = s1->got->data_offset;
section_ptr_add(s1->got, PTR_SIZE);
/* Create the GOT relocation that will insert the address of the object or
function of interest in the GOT entry. This is a static relocation for
memory output (dlsym will give us the address of symbols) and dynamic
relocation otherwise (executable and DLLs). The relocation should be
done lazily for GOT entry with *_JUMP_SLOT relocation type (the one
associated to a PLT entry) but is currently done at load time for an
unknown reason. */
sym = &((ElfW(Sym) *) symtab_section->data)[sym_index];
name = (char *) symtab_section->link->data + sym->st_name;
if (s1->dynsym) {
if (0 == attr->dyn_index)
attr->dyn_index = set_elf_sym(s1->dynsym, sym->st_value, size,
info, 0, sym->st_shndx, name);
put_elf_reloc(s1->dynsym, s1->got, got_offset, dyn_reloc_type,
attr->dyn_index);
} else {
put_elf_reloc(symtab_section, s1->got, got_offset, dyn_reloc_type,
sym_index);
}
if (need_plt_entry) {
if (!s1->plt) {
s1->plt = new_section(s1, ".plt", SHT_PROGBITS,
SHF_ALLOC | SHF_EXECINSTR);
s1->plt->sh_entsize = 4;
}
attr->plt_offset = create_plt_entry(s1, got_offset, attr);
/* create a symbol 'sym@plt' for the PLT jump vector */
len = strlen(name);
if (len > sizeof plt_name - 5)
len = sizeof plt_name - 5;
memcpy(plt_name, name, len);
strcpy(plt_name + len, "@plt");
attr->plt_sym = put_elf_sym(s1->symtab, attr->plt_offset, sym->st_size,
ELFW(ST_INFO)(STB_GLOBAL, STT_FUNC), 0, s1->plt->sh_num, plt_name);
} else {
attr->got_offset = got_offset;
}
return attr;
}
/* build GOT and PLT entries */
ST_FUNC void build_got_entries(TCCState *s1)
{
Section *s;
ElfW_Rel *rel;
ElfW(Sym) *sym;
int i, type, gotplt_entry, reloc_type, sym_index;
struct sym_attr *attr;
for(i = 1; i < s1->nb_sections; i++) {
s = s1->sections[i];
if (s->sh_type != SHT_RELX)
continue;
/* no need to handle got relocations */
if (s->link != symtab_section)
continue;
for_each_elem(s, 0, rel, ElfW_Rel) {
type = ELFW(R_TYPE)(rel->r_info);
gotplt_entry = gotplt_entry_type(type);
sym_index = ELFW(R_SYM)(rel->r_info);
sym = &((ElfW(Sym) *)symtab_section->data)[sym_index];
if (gotplt_entry == NO_GOTPLT_ENTRY) {
continue;
}
/* Automatically create PLT/GOT [entry] if it is an undefined
reference (resolved at runtime), or the symbol is absolute,
probably created by tcc_add_symbol, and thus on 64-bit
targets might be too far from application code. */
if (gotplt_entry == AUTO_GOTPLT_ENTRY) {
if (sym->st_shndx == SHN_UNDEF) {
ElfW(Sym) *esym;
int dynindex;
if (s1->output_type == TCC_OUTPUT_DLL && ! PCRELATIVE_DLLPLT)
continue;
/* Relocations for UNDEF symbols would normally need
to be transferred into the executable or shared object.
If that were done AUTO_GOTPLT_ENTRY wouldn't exist.
But TCC doesn't do that (at least for exes), so we
need to resolve all such relocs locally. And that
means PLT slots for functions in DLLs and COPY relocs for
data symbols. COPY relocs were generated in
bind_exe_dynsyms (and the symbol adjusted to be defined),
and for functions we were generated a dynamic symbol
of function type. */
if (s1->dynsym) {
/* dynsym isn't set for -run :-/ */
dynindex = get_sym_attr(s1, sym_index, 0)->dyn_index;
esym = (ElfW(Sym) *)s1->dynsym->data + dynindex;
if (dynindex
&& (ELFW(ST_TYPE)(esym->st_info) == STT_FUNC
|| (ELFW(ST_TYPE)(esym->st_info) == STT_NOTYPE
&& ELFW(ST_TYPE)(sym->st_info) == STT_FUNC)))
goto jmp_slot;
}
} else if (!(sym->st_shndx == SHN_ABS && PTR_SIZE == 8))
continue;
}
#ifdef TCC_TARGET_X86_64
if (type == R_X86_64_PLT32 &&
ELFW(ST_VISIBILITY)(sym->st_other) != STV_DEFAULT) {
rel->r_info = ELFW(R_INFO)(sym_index, R_X86_64_PC32);
continue;