aboutsummaryrefslogtreecommitdiff
path: root/gold/i386.cc
blob: 837f5abdf843dfd181452739bc371e2aa0d7559b (plain)
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
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
// i386.cc -- i386 target support for gold.

// Copyright 2006, 2007 Free Software Foundation, Inc.
// Written by Ian Lance Taylor <iant@google.com>.

// This file is part of gold.

// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3 of the License, or
// (at your option) any later version.

// This program 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 General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
// MA 02110-1301, USA.

#include "gold.h"

#include <cstring>

#include "elfcpp.h"
#include "parameters.h"
#include "reloc.h"
#include "i386.h"
#include "object.h"
#include "symtab.h"
#include "layout.h"
#include "output.h"
#include "target.h"
#include "target-reloc.h"
#include "target-select.h"
#include "tls.h"

namespace
{

using namespace gold;

class Output_data_plt_i386;

// The i386 target class.
// TLS info comes from
//   http://people.redhat.com/drepper/tls.pdf
//   http://www.lsd.ic.unicamp.br/~oliva/writeups/TLS/RFC-TLSDESC-x86.txt

class Target_i386 : public Sized_target<32, false>
{
 public:
  typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, false> Reloc_section;

  Target_i386()
    : Sized_target<32, false>(&i386_info),
      got_(NULL), plt_(NULL), got_plt_(NULL), rel_dyn_(NULL),
      copy_relocs_(NULL), dynbss_(NULL)
  { }

  // Scan the relocations to look for symbol adjustments.
  void
  scan_relocs(const General_options& options,
	      Symbol_table* symtab,
	      Layout* layout,
	      Sized_relobj<32, false>* object,
	      unsigned int data_shndx,
	      unsigned int sh_type,
	      const unsigned char* prelocs,
	      size_t reloc_count,
	      size_t local_symbol_count,
	      const unsigned char* plocal_symbols,
	      Symbol** global_symbols);

  // Finalize the sections.
  void
  do_finalize_sections(Layout*);

  // Return the value to use for a dynamic which requires special
  // treatment.
  uint64_t
  do_dynsym_value(const Symbol*) const;

  // Relocate a section.
  void
  relocate_section(const Relocate_info<32, false>*,
		   unsigned int sh_type,
		   const unsigned char* prelocs,
		   size_t reloc_count,
		   unsigned char* view,
		   elfcpp::Elf_types<32>::Elf_Addr view_address,
		   off_t view_size);

  // Return a string used to fill a code section with nops.
  std::string
  do_code_fill(off_t length);

 private:
  // The class which scans relocations.
  struct Scan
  {
    inline void
    local(const General_options& options, Symbol_table* symtab,
	  Layout* layout, Target_i386* target,
	  Sized_relobj<32, false>* object,
	  unsigned int data_shndx,
	  const elfcpp::Rel<32, false>& reloc, unsigned int r_type,
	  const elfcpp::Sym<32, false>& lsym);

    inline void
    global(const General_options& options, Symbol_table* symtab,
	   Layout* layout, Target_i386* target,
	   Sized_relobj<32, false>* object,
	   unsigned int data_shndx,
	   const elfcpp::Rel<32, false>& reloc, unsigned int r_type,
	   Symbol* gsym);

    static void
    unsupported_reloc_local(Sized_relobj<32, false>*, unsigned int r_type);

    static void
    unsupported_reloc_global(Sized_relobj<32, false>*, unsigned int r_type,
			     Symbol*);
  };

  // The class which implements relocation.
  class Relocate
  {
   public:
    Relocate()
      : skip_call_tls_get_addr_(false),
	local_dynamic_type_(LOCAL_DYNAMIC_NONE)
    { }

    ~Relocate()
    {
      if (this->skip_call_tls_get_addr_)
	{
	  // FIXME: This needs to specify the location somehow.
	  gold_error(_("missing expected TLS relocation"));
	}
    }

    // Do a relocation.  Return false if the caller should not issue
    // any warnings about this relocation.
    inline bool
    relocate(const Relocate_info<32, false>*, Target_i386*, size_t relnum,
	     const elfcpp::Rel<32, false>&,
	     unsigned int r_type, const Sized_symbol<32>*,
	     const Symbol_value<32>*,
	     unsigned char*, elfcpp::Elf_types<32>::Elf_Addr,
	     off_t);

   private:
    // Do a TLS relocation.
    inline void
    relocate_tls(const Relocate_info<32, false>*, size_t relnum,
		 const elfcpp::Rel<32, false>&,
		 unsigned int r_type, const Sized_symbol<32>*,
		 const Symbol_value<32>*,
		 unsigned char*, elfcpp::Elf_types<32>::Elf_Addr, off_t);

    // Do a TLS Initial-Exec to Local-Exec transition.
    static inline void
    tls_ie_to_le(const Relocate_info<32, false>*, size_t relnum,
		 Output_segment* tls_segment,
		 const elfcpp::Rel<32, false>&, unsigned int r_type,
		 elfcpp::Elf_types<32>::Elf_Addr value,
		 unsigned char* view,
		 off_t view_size);

    // Do a TLS General-Dynamic to Local-Exec transition.
    inline void
    tls_gd_to_le(const Relocate_info<32, false>*, size_t relnum,
		 Output_segment* tls_segment,
		 const elfcpp::Rel<32, false>&, unsigned int r_type,
		 elfcpp::Elf_types<32>::Elf_Addr value,
		 unsigned char* view,
		 off_t view_size);

    // Do a TLS Local-Dynamic to Local-Exec transition.
    inline void
    tls_ld_to_le(const Relocate_info<32, false>*, size_t relnum,
		 Output_segment* tls_segment,
		 const elfcpp::Rel<32, false>&, unsigned int r_type,
		 elfcpp::Elf_types<32>::Elf_Addr value,
		 unsigned char* view,
		 off_t view_size);

    // We need to keep track of which type of local dynamic relocation
    // we have seen, so that we can optimize R_386_TLS_LDO_32 correctly.
    enum Local_dynamic_type
    {
      LOCAL_DYNAMIC_NONE,
      LOCAL_DYNAMIC_SUN,
      LOCAL_DYNAMIC_GNU
    };

    // This is set if we should skip the next reloc, which should be a
    // PLT32 reloc against ___tls_get_addr.
    bool skip_call_tls_get_addr_;
    // The type of local dynamic relocation we have seen in the section
    // being relocated, if any.
    Local_dynamic_type local_dynamic_type_;
  };

  // Adjust TLS relocation type based on the options and whether this
  // is a local symbol.
  static tls::Tls_optimization
  optimize_tls_reloc(bool is_final, int r_type);

  // Get the GOT section, creating it if necessary.
  Output_data_got<32, false>*
  got_section(Symbol_table*, Layout*);

  // Create a PLT entry for a global symbol.
  void
  make_plt_entry(Symbol_table*, Layout*, Symbol*);

  // Get the PLT section.
  const Output_data_plt_i386*
  plt_section() const
  {
    gold_assert(this->plt_ != NULL);
    return this->plt_;
  }

  // Get the dynamic reloc section, creating it if necessary.
  Reloc_section*
  rel_dyn_section(Layout*);

  // Copy a relocation against a global symbol.
  void
  copy_reloc(const General_options*, Symbol_table*, Layout*,
	     Sized_relobj<32, false>*, unsigned int,
	     Symbol*, const elfcpp::Rel<32, false>&);

  // Information about this specific target which we pass to the
  // general Target structure.
  static const Target::Target_info i386_info;

  // The GOT section.
  Output_data_got<32, false>* got_;
  // The PLT section.
  Output_data_plt_i386* plt_;
  // The GOT PLT section.
  Output_data_space* got_plt_;
  // The dynamic reloc section.
  Reloc_section* rel_dyn_;
  // Relocs saved to avoid a COPY reloc.
  Copy_relocs<32, false>* copy_relocs_;
  // Space for variables copied with a COPY reloc.
  Output_data_space* dynbss_;
};

const Target::Target_info Target_i386::i386_info =
{
  32,			// size
  false,		// is_big_endian
  elfcpp::EM_386,	// machine_code
  false,		// has_make_symbol
  false,		// has_resolve
  true,			// has_code_fill
  "/usr/lib/libc.so.1",	// dynamic_linker
  0x08048000,		// text_segment_address
  0x1000,		// abi_pagesize
  0x1000		// common_pagesize
};

// Get the GOT section, creating it if necessary.

Output_data_got<32, false>*
Target_i386::got_section(Symbol_table* symtab, Layout* layout)
{
  if (this->got_ == NULL)
    {
      gold_assert(symtab != NULL && layout != NULL);

      this->got_ = new Output_data_got<32, false>();

      layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
				      elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
				      this->got_);

      // The old GNU linker creates a .got.plt section.  We just
      // create another set of data in the .got section.  Note that we
      // always create a PLT if we create a GOT, although the PLT
      // might be empty.
      this->got_plt_ = new Output_data_space(4);
      layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
				      elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
				      this->got_plt_);

      // The first three entries are reserved.
      this->got_plt_->set_space_size(3 * 4);

      // Define _GLOBAL_OFFSET_TABLE_ at the start of the PLT.
      symtab->define_in_output_data(this, "_GLOBAL_OFFSET_TABLE_", NULL,
				    this->got_plt_,
				    0, 0, elfcpp::STT_OBJECT,
				    elfcpp::STB_LOCAL,
				    elfcpp::STV_HIDDEN, 0,
				    false, false);
    }

  return this->got_;
}

// Get the dynamic reloc section, creating it if necessary.

Target_i386::Reloc_section*
Target_i386::rel_dyn_section(Layout* layout)
{
  if (this->rel_dyn_ == NULL)
    {
      gold_assert(layout != NULL);
      this->rel_dyn_ = new Reloc_section();
      layout->add_output_section_data(".rel.dyn", elfcpp::SHT_REL,
				      elfcpp::SHF_ALLOC, this->rel_dyn_);
    }
  return this->rel_dyn_;
}

// A class to handle the PLT data.

class Output_data_plt_i386 : public Output_section_data
{
 public:
  typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, false> Reloc_section;

  Output_data_plt_i386(Layout*, Output_data_space*);

  // Add an entry to the PLT.
  void
  add_entry(Symbol* gsym);

  // Return the .rel.plt section data.
  const Reloc_section*
  rel_plt() const
  { return this->rel_; }

 protected:
  void
  do_adjust_output_section(Output_section* os);

 private:
  // The size of an entry in the PLT.
  static const int plt_entry_size = 16;

  // The first entry in the PLT for an executable.
  static unsigned char exec_first_plt_entry[plt_entry_size];

  // The first entry in the PLT for a shared object.
  static unsigned char dyn_first_plt_entry[plt_entry_size];

  // Other entries in the PLT for an executable.
  static unsigned char exec_plt_entry[plt_entry_size];

  // Other entries in the PLT for a shared object.
  static unsigned char dyn_plt_entry[plt_entry_size];

  // Set the final size.
  void
  do_set_address(uint64_t, off_t)
  { this->set_data_size((this->count_ + 1) * plt_entry_size); }

  // Write out the PLT data.
  void
  do_write(Output_file*);

  // The reloc section.
  Reloc_section* rel_;
  // The .got.plt section.
  Output_data_space* got_plt_;
  // The number of PLT entries.
  unsigned int count_;
};

// Create the PLT section.  The ordinary .got section is an argument,
// since we need to refer to the start.  We also create our own .got
// section just for PLT entries.

Output_data_plt_i386::Output_data_plt_i386(Layout* layout,
					   Output_data_space* got_plt)
  : Output_section_data(4), got_plt_(got_plt), count_(0)
{
  this->rel_ = new Reloc_section();
  layout->add_output_section_data(".rel.plt", elfcpp::SHT_REL,
				  elfcpp::SHF_ALLOC, this->rel_);
}

void
Output_data_plt_i386::do_adjust_output_section(Output_section* os)
{
  // UnixWare sets the entsize of .plt to 4, and so does the old GNU
  // linker, and so do we.
  os->set_entsize(4);
}

// Add an entry to the PLT.

void
Output_data_plt_i386::add_entry(Symbol* gsym)
{
  gold_assert(!gsym->has_plt_offset());

  // Note that when setting the PLT offset we skip the initial
  // reserved PLT entry.
  gsym->set_plt_offset((this->count_ + 1) * plt_entry_size);

  ++this->count_;

  off_t got_offset = this->got_plt_->data_size();

  // Every PLT entry needs a GOT entry which points back to the PLT
  // entry (this will be changed by the dynamic linker, normally
  // lazily when the function is called).
  this->got_plt_->set_space_size(got_offset + 4);

  // Every PLT entry needs a reloc.
  gsym->set_needs_dynsym_entry();
  this->rel_->add_global(gsym, elfcpp::R_386_JUMP_SLOT, this->got_plt_,
			 got_offset);

  // Note that we don't need to save the symbol.  The contents of the
  // PLT are independent of which symbols are used.  The symbols only
  // appear in the relocations.
}

// The first entry in the PLT for an executable.

unsigned char Output_data_plt_i386::exec_first_plt_entry[plt_entry_size] =
{
  0xff, 0x35,	// pushl contents of memory address
  0, 0, 0, 0,	// replaced with address of .got + 4
  0xff, 0x25,	// jmp indirect
  0, 0, 0, 0,	// replaced with address of .got + 8
  0, 0, 0, 0	// unused
};

// The first entry in the PLT for a shared object.

unsigned char Output_data_plt_i386::dyn_first_plt_entry[plt_entry_size] =
{
  0xff, 0xb3, 4, 0, 0, 0,	// pushl 4(%ebx)
  0xff, 0xa3, 8, 0, 0, 0,	// jmp *8(%ebx)
  0, 0, 0, 0			// unused
};

// Subsequent entries in the PLT for an executable.

unsigned char Output_data_plt_i386::exec_plt_entry[plt_entry_size] =
{
  0xff, 0x25,	// jmp indirect
  0, 0, 0, 0,	// replaced with address of symbol in .got
  0x68,		// pushl immediate
  0, 0, 0, 0,	// replaced with offset into relocation table
  0xe9,		// jmp relative
  0, 0, 0, 0	// replaced with offset to start of .plt
};

// Subsequent entries in the PLT for a shared object.

unsigned char Output_data_plt_i386::dyn_plt_entry[plt_entry_size] =
{
  0xff, 0xa3,	// jmp *offset(%ebx)
  0, 0, 0, 0,	// replaced with offset of symbol in .got
  0x68,		// pushl immediate
  0, 0, 0, 0,	// replaced with offset into relocation table
  0xe9,		// jmp relative
  0, 0, 0, 0	// replaced with offset to start of .plt
};

// Write out the PLT.  This uses the hand-coded instructions above,
// and adjusts them as needed.  This is all specified by the i386 ELF
// Processor Supplement.

void
Output_data_plt_i386::do_write(Output_file* of)
{
  const off_t offset = this->offset();
  const off_t oview_size = this->data_size();
  unsigned char* const oview = of->get_output_view(offset, oview_size);

  const off_t got_file_offset = this->got_plt_->offset();
  const off_t got_size = this->got_plt_->data_size();
  unsigned char* const got_view = of->get_output_view(got_file_offset,
						      got_size);

  unsigned char* pov = oview;

  elfcpp::Elf_types<32>::Elf_Addr plt_address = this->address();
  elfcpp::Elf_types<32>::Elf_Addr got_address = this->got_plt_->address();

  if (parameters->output_is_shared())
    memcpy(pov, dyn_first_plt_entry, plt_entry_size);
  else
    {
      memcpy(pov, exec_first_plt_entry, plt_entry_size);
      elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_address + 4);
      elfcpp::Swap<32, false>::writeval(pov + 8, got_address + 8);
    }
  pov += plt_entry_size;

  unsigned char* got_pov = got_view;

  memset(got_pov, 0, 12);
  got_pov += 12;

  const int rel_size = elfcpp::Elf_sizes<32>::rel_size;

  unsigned int plt_offset = plt_entry_size;
  unsigned int plt_rel_offset = 0;
  unsigned int got_offset = 12;
  const unsigned int count = this->count_;
  for (unsigned int i = 0;
       i < count;
       ++i,
	 pov += plt_entry_size,
	 got_pov += 4,
	 plt_offset += plt_entry_size,
	 plt_rel_offset += rel_size,
	 got_offset += 4)
    {
      // Set and adjust the PLT entry itself.

      if (parameters->output_is_shared())
	{
	  memcpy(pov, dyn_plt_entry, plt_entry_size);
	  elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_offset);
	}
      else
	{
	  memcpy(pov, exec_plt_entry, plt_entry_size);
	  elfcpp::Swap_unaligned<32, false>::writeval(pov + 2,
						      (got_address
						       + got_offset));
	}

      elfcpp::Swap_unaligned<32, false>::writeval(pov + 7, plt_rel_offset);
      elfcpp::Swap<32, false>::writeval(pov + 12,
					- (plt_offset + plt_entry_size));

      // Set the entry in the GOT.
      elfcpp::Swap<32, false>::writeval(got_pov, plt_address + plt_offset + 6);
    }

  gold_assert(pov - oview == oview_size);
  gold_assert(got_pov - got_view == got_size);

  of->write_output_view(offset, oview_size, oview);
  of->write_output_view(got_file_offset, got_size, got_view);
}

// Create a PLT entry for a global symbol.

void
Target_i386::make_plt_entry(Symbol_table* symtab, Layout* layout, Symbol* gsym)
{
  if (gsym->has_plt_offset())
    return;

  if (this->plt_ == NULL)
    {
      // Create the GOT sections first.
      this->got_section(symtab, layout);

      this->plt_ = new Output_data_plt_i386(layout, this->got_plt_);
      layout->add_output_section_data(".plt", elfcpp::SHT_PROGBITS,
				      (elfcpp::SHF_ALLOC
				       | elfcpp::SHF_EXECINSTR),
				      this->plt_);
    }

  this->plt_->add_entry(gsym);
}

// Handle a relocation against a non-function symbol defined in a
// dynamic object.  The traditional way to handle this is to generate
// a COPY relocation to copy the variable at runtime from the shared
// object into the executable's data segment.  However, this is
// undesirable in general, as if the size of the object changes in the
// dynamic object, the executable will no longer work correctly.  If
// this relocation is in a writable section, then we can create a
// dynamic reloc and the dynamic linker will resolve it to the correct
// address at runtime.  However, we do not want do that if the
// relocation is in a read-only section, as it would prevent the
// readonly segment from being shared.  And if we have to eventually
// generate a COPY reloc, then any dynamic relocations will be
// useless.  So this means that if this is a writable section, we need
// to save the relocation until we see whether we have to create a
// COPY relocation for this symbol for any other relocation.

void
Target_i386::copy_reloc(const General_options* options,
			Symbol_table* symtab,
			Layout* layout,
			Sized_relobj<32, false>* object,
			unsigned int data_shndx, Symbol* gsym,
			const elfcpp::Rel<32, false>& rel)
{
  Sized_symbol<32>* ssym;
  ssym = symtab->get_sized_symbol SELECT_SIZE_NAME(32) (gsym
							SELECT_SIZE(32));

  if (!Copy_relocs<32, false>::need_copy_reloc(options, object,
					       data_shndx, ssym))
    {
      // So far we do not need a COPY reloc.  Save this relocation.
      // If it turns out that we never need a COPY reloc for this
      // symbol, then we will emit the relocation.
      if (this->copy_relocs_ == NULL)
	this->copy_relocs_ = new Copy_relocs<32, false>();
      this->copy_relocs_->save(ssym, object, data_shndx, rel);
    }
  else
    {
      // Allocate space for this symbol in the .bss section.

      elfcpp::Elf_types<32>::Elf_WXword symsize = ssym->symsize();

      // There is no defined way to determine the required alignment
      // of the symbol.  We pick the alignment based on the size.  We
      // set an arbitrary maximum of 256.
      unsigned int align;
      for (align = 1; align < 512; align <<= 1)
	if ((symsize & align) != 0)
	  break;

      if (this->dynbss_ == NULL)
	{
	  this->dynbss_ = new Output_data_space(align);
	  layout->add_output_section_data(".bss",
					  elfcpp::SHT_NOBITS,
					  (elfcpp::SHF_ALLOC
					   | elfcpp::SHF_WRITE),
					  this->dynbss_);
	}

      Output_data_space* dynbss = this->dynbss_;

      if (align > dynbss->addralign())
	dynbss->set_space_alignment(align);

      off_t dynbss_size = dynbss->data_size();
      dynbss_size = align_address(dynbss_size, align);
      off_t offset = dynbss_size;
      dynbss->set_space_size(dynbss_size + symsize);

      // Define the symbol in the .dynbss section.
      symtab->define_in_output_data(this, ssym->name(), ssym->version(),
				    dynbss, offset, symsize, ssym->type(),
				    ssym->binding(), ssym->visibility(),
				    ssym->nonvis(), false, false);

      // Add the COPY reloc.
      ssym->set_needs_dynsym_entry();
      Reloc_section* rel_dyn = this->rel_dyn_section(layout);
      rel_dyn->add_global(ssym, elfcpp::R_386_COPY, dynbss, offset);
    }
}

// Optimize the TLS relocation type based on what we know about the
// symbol.  IS_FINAL is true if the final address of this symbol is
// known at link time.

tls::Tls_optimization
Target_i386::optimize_tls_reloc(bool is_final, int r_type)
{
  // If we are generating a shared library, then we can't do anything
  // in the linker.
  if (parameters->output_is_shared())
    return tls::TLSOPT_NONE;

  switch (r_type)
    {
    case elfcpp::R_386_TLS_GD:
    case elfcpp::R_386_TLS_GOTDESC:
    case elfcpp::R_386_TLS_DESC_CALL:
      // These are General-Dynamic which permits fully general TLS
      // access.  Since we know that we are generating an executable,
      // we can convert this to Initial-Exec.  If we also know that
      // this is a local symbol, we can further switch to Local-Exec.
      if (is_final)
	return tls::TLSOPT_TO_LE;
      return tls::TLSOPT_TO_IE;

    case elfcpp::R_386_TLS_LDM:
      // This is Local-Dynamic, which refers to a local symbol in the
      // dynamic TLS block.  Since we know that we generating an
      // executable, we can switch to Local-Exec.
      return tls::TLSOPT_TO_LE;

    case elfcpp::R_386_TLS_LDO_32:
      // Another type of Local-Dynamic relocation.
      return tls::TLSOPT_TO_LE;

    case elfcpp::R_386_TLS_IE:
    case elfcpp::R_386_TLS_GOTIE:
    case elfcpp::R_386_TLS_IE_32:
      // These are Initial-Exec relocs which get the thread offset
      // from the GOT.  If we know that we are linking against the
      // local symbol, we can switch to Local-Exec, which links the
      // thread offset into the instruction.
      if (is_final)
	return tls::TLSOPT_TO_LE;
      return tls::TLSOPT_NONE;

    case elfcpp::R_386_TLS_LE:
    case elfcpp::R_386_TLS_LE_32:
      // When we already have Local-Exec, there is nothing further we
      // can do.
      return tls::TLSOPT_NONE;

    default:
      gold_unreachable();
    }
}

// Report an unsupported relocation against a local symbol.

void
Target_i386::Scan::unsupported_reloc_local(Sized_relobj<32, false>* object,
					   unsigned int r_type)
{
  gold_error(_("%s: unsupported reloc %u against local symbol"),
	     object->name().c_str(), r_type);
}

// Scan a relocation for a local symbol.

inline void
Target_i386::Scan::local(const General_options&,
			 Symbol_table* symtab,
			 Layout* layout,
			 Target_i386* target,
			 Sized_relobj<32, false>* object,
			 unsigned int,
			 const elfcpp::Rel<32, false>&,
			 unsigned int r_type,
			 const elfcpp::Sym<32, false>&)
{
  switch (r_type)
    {
    case elfcpp::R_386_NONE:
    case elfcpp::R_386_GNU_VTINHERIT:
    case elfcpp::R_386_GNU_VTENTRY:
      break;

    case elfcpp::R_386_32:
    case elfcpp::R_386_16:
    case elfcpp::R_386_8:
      // FIXME: If we are generating a shared object we need to copy
      // this relocation into the object.
      gold_assert(!parameters->output_is_shared());
      break;

    case elfcpp::R_386_PC32:
    case elfcpp::R_386_PC16:
    case elfcpp::R_386_PC8:
      break;

    case elfcpp::R_386_GOTOFF:
    case elfcpp::R_386_GOTPC:
      // We need a GOT section.
      target->got_section(symtab, layout);
      break;

      // These are relocations which should only be seen by the
      // dynamic linker, and should never be seen here.
    case elfcpp::R_386_COPY:
    case elfcpp::R_386_GLOB_DAT:
    case elfcpp::R_386_JUMP_SLOT:
    case elfcpp::R_386_RELATIVE:
    case elfcpp::R_386_TLS_TPOFF:
    case elfcpp::R_386_TLS_DTPMOD32:
    case elfcpp::R_386_TLS_DTPOFF32:
    case elfcpp::R_386_TLS_TPOFF32:
    case elfcpp::R_386_TLS_DESC:
      gold_error(_("%s: unexpected reloc %u in object file\n"),
		 object->name().c_str(), r_type);
      break;

      // These are initial TLS relocs, which are expected when
      // linking.
    case elfcpp::R_386_TLS_IE:
    case elfcpp::R_386_TLS_GOTIE:
    case elfcpp::R_386_TLS_LE:
    case elfcpp::R_386_TLS_GD:
    case elfcpp::R_386_TLS_LDM:
    case elfcpp::R_386_TLS_LDO_32:
    case elfcpp::R_386_TLS_IE_32:
    case elfcpp::R_386_TLS_LE_32:
    case elfcpp::R_386_TLS_GOTDESC:
    case elfcpp::R_386_TLS_DESC_CALL:
      {
	bool output_is_shared = parameters->output_is_shared();
	const tls::Tls_optimization optimized_type
            = Target_i386::optimize_tls_reloc(!output_is_shared, r_type);
	switch (r_type)
	  {
	  case elfcpp::R_386_TLS_LE:
	  case elfcpp::R_386_TLS_LE_32:
	    // FIXME: If generating a shared object, we need to copy
	    // this relocation into the object.
	    gold_assert(!output_is_shared);
	    break;

	  case elfcpp::R_386_TLS_IE:
	  case elfcpp::R_386_TLS_IE_32:
	  case elfcpp::R_386_TLS_GOTIE:
	    // FIXME: If not relaxing to LE, we need to generate a
	    // TPOFF or TPOFF32 reloc.
	    if (optimized_type != tls::TLSOPT_TO_LE)
	      unsupported_reloc_local(object, r_type);
	    break;

	  case elfcpp::R_386_TLS_LDM:
	    // FIXME: If not relaxing to LE, we need to generate a
	    // DTPMOD32 reloc.
	    if (optimized_type != tls::TLSOPT_TO_LE)
	      unsupported_reloc_local(object, r_type);
	    break;

	  case elfcpp::R_386_TLS_LDO_32:
	    break;

	  case elfcpp::R_386_TLS_GD:
	  case elfcpp::R_386_TLS_GOTDESC:
	  case elfcpp::R_386_TLS_DESC_CALL:
	    // FIXME: If not relaxing to LE, we need to generate
	    // DTPMOD32 and DTPOFF32 relocs.
	    if (optimized_type != tls::TLSOPT_TO_LE)
	      unsupported_reloc_local(object, r_type);
	    break;

	  default:
	    gold_unreachable();
	  }
      }
      break;

    case elfcpp::R_386_GOT32:
    case elfcpp::R_386_PLT32:
    case elfcpp::R_386_32PLT:
    case elfcpp::R_386_TLS_GD_32:
    case elfcpp::R_386_TLS_GD_PUSH:
    case elfcpp::R_386_TLS_GD_CALL:
    case elfcpp::R_386_TLS_GD_POP:
    case elfcpp::R_386_TLS_LDM_32:
    case elfcpp::R_386_TLS_LDM_PUSH:
    case elfcpp::R_386_TLS_LDM_CALL:
    case elfcpp::R_386_TLS_LDM_POP:
    case elfcpp::R_386_USED_BY_INTEL_200:
    default:
      unsupported_reloc_local(object, r_type);
      break;
    }
}

// Report an unsupported relocation against a global symbol.

void
Target_i386::Scan::unsupported_reloc_global(Sized_relobj<32, false>* object,
					    unsigned int r_type,
					    Symbol* gsym)
{
  gold_error(_("%s: unsupported reloc %u against global symbol %s"),
	     object->name().c_str(), r_type, gsym->name());
}

// Scan a relocation for a global symbol.

inline void
Target_i386::Scan::global(const General_options& options,
			  Symbol_table* symtab,
			  Layout* layout,
			  Target_i386* target,
			  Sized_relobj<32, false>* object,
			  unsigned int data_shndx,
			  const elfcpp::Rel<32, false>& reloc,
			  unsigned int r_type,
			  Symbol* gsym)
{
  switch (r_type)
    {
    case elfcpp::R_386_NONE:
    case elfcpp::R_386_GNU_VTINHERIT:
    case elfcpp::R_386_GNU_VTENTRY:
      break;

    case elfcpp::R_386_32:
    case elfcpp::R_386_PC32:
    case elfcpp::R_386_16:
    case elfcpp::R_386_PC16:
    case elfcpp::R_386_8:
    case elfcpp::R_386_PC8:
      // FIXME: If we are generating a shared object we may need to
      // copy this relocation into the object.  If this symbol is
      // defined in a shared object, we may need to copy this
      // relocation in order to avoid a COPY relocation.
      gold_assert(!parameters->output_is_shared());

      if (gsym->is_from_dynobj())
	{
	  // This symbol is defined in a dynamic object.  If it is a
	  // function, we make a PLT entry.  Otherwise we need to
	  // either generate a COPY reloc or copy this reloc.
	  if (gsym->type() == elfcpp::STT_FUNC)
	    {
	      target->make_plt_entry(symtab, layout, gsym);

	      // If this is not a PC relative reference, then we may
	      // be taking the address of the function.  In that case
	      // we need to set the entry in the dynamic symbol table
	      // to the address of the PLT entry.
	      if (r_type != elfcpp::R_386_PC32
		  && r_type != elfcpp::R_386_PC16
		  && r_type != elfcpp::R_386_PC8)
		gsym->set_needs_dynsym_value();
	    }
	  else
	    target->copy_reloc(&options, symtab, layout, object, data_shndx,
			       gsym, reloc);
	}

      break;

    case elfcpp::R_386_GOT32:
      {
        // The symbol requires a GOT entry.
        Output_data_got<32, false>* got = target->got_section(symtab, layout);
        if (got->add_global(gsym))
	  {
            // If this symbol is not fully resolved, we need to add a
            // dynamic relocation for it.
            if (!gsym->final_value_is_known())
              {
                Reloc_section* rel_dyn = target->rel_dyn_section(layout);
                rel_dyn->add_global(gsym, elfcpp::R_386_GLOB_DAT, got,
                                    gsym->got_offset());
              }
          }
      }
      break;

    case elfcpp::R_386_PLT32:
      // If the symbol is fully resolved, this is just a PC32 reloc.
      // Otherwise we need a PLT entry.
      if (gsym->final_value_is_known())
	break;
      target->make_plt_entry(symtab, layout, gsym);
      break;

    case elfcpp::R_386_GOTOFF:
    case elfcpp::R_386_GOTPC:
      // We need a GOT section.
      target->got_section(symtab, layout);
      break;

      // These are relocations which should only be seen by the
      // dynamic linker, and should never be seen here.
    case elfcpp::R_386_COPY:
    case elfcpp::R_386_GLOB_DAT:
    case elfcpp::R_386_JUMP_SLOT:
    case elfcpp::R_386_RELATIVE:
    case elfcpp::R_386_TLS_TPOFF:
    case elfcpp::R_386_TLS_DTPMOD32:
    case elfcpp::R_386_TLS_DTPOFF32:
    case elfcpp::R_386_TLS_TPOFF32:
    case elfcpp::R_386_TLS_DESC:
      gold_error(_("%s: unexpected reloc %u in object file"),
		 object->name().c_str(), r_type);
      break;

      // These are initial tls relocs, which are expected when
      // linking.
    case elfcpp::R_386_TLS_IE:
    case elfcpp::R_386_TLS_GOTIE:
    case elfcpp::R_386_TLS_LE:
    case elfcpp::R_386_TLS_GD:
    case elfcpp::R_386_TLS_LDM:
    case elfcpp::R_386_TLS_LDO_32:
    case elfcpp::R_386_TLS_IE_32:
    case elfcpp::R_386_TLS_LE_32:
    case elfcpp::R_386_TLS_GOTDESC:
    case elfcpp::R_386_TLS_DESC_CALL:
      {
	const bool is_final = gsym->final_value_is_known();
	const tls::Tls_optimization optimized_type
            = Target_i386::optimize_tls_reloc(is_final, r_type);
	switch (r_type)
	  {
	  case elfcpp::R_386_TLS_LE:
	  case elfcpp::R_386_TLS_LE_32:
	    // FIXME: If generating a shared object, we need to copy
	    // this relocation into the object.
	    gold_assert(!parameters->output_is_shared());
	    break;

	  case elfcpp::R_386_TLS_IE:
	  case elfcpp::R_386_TLS_IE_32:
	  case elfcpp::R_386_TLS_GOTIE:
	    // FIXME: If not relaxing to LE, we need to generate a
	    // TPOFF or TPOFF32 reloc.
	    if (optimized_type != tls::TLSOPT_TO_LE)
	      unsupported_reloc_global(object, r_type, gsym);
	    break;

	  case elfcpp::R_386_TLS_LDM:
	    // FIXME: If not relaxing to LE, we need to generate a
	    // DTPMOD32 reloc.
	    if (optimized_type != tls::TLSOPT_TO_LE)
	      unsupported_reloc_global(object, r_type, gsym);
	    break;

	  case elfcpp::R_386_TLS_LDO_32:
	    break;

	  case elfcpp::R_386_TLS_GD:
	  case elfcpp::R_386_TLS_GOTDESC:
	  case elfcpp::R_386_TLS_DESC_CALL:
	    // FIXME: If not relaxing to LE, we need to generate
	    // DTPMOD32 and DTPOFF32 relocs.
	    if (optimized_type != tls::TLSOPT_TO_LE)
	      unsupported_reloc_global(object, r_type, gsym);
	    break;

	  default:
	    gold_unreachable();
	  }
      }
      break;

    case elfcpp::R_386_32PLT:
    case elfcpp::R_386_TLS_GD_32:
    case elfcpp::R_386_TLS_GD_PUSH:
    case elfcpp::R_386_TLS_GD_CALL:
    case elfcpp::R_386_TLS_GD_POP:
    case elfcpp::R_386_TLS_LDM_32:
    case elfcpp::R_386_TLS_LDM_PUSH:
    case elfcpp::R_386_TLS_LDM_CALL:
    case elfcpp::R_386_TLS_LDM_POP:
    case elfcpp::R_386_USED_BY_INTEL_200:
    default:
      unsupported_reloc_global(object, r_type, gsym);
      break;
    }
}

// Scan relocations for a section.

void
Target_i386::scan_relocs(const General_options& options,
			 Symbol_table* symtab,
			 Layout* layout,
			 Sized_relobj<32, false>* object,
			 unsigned int data_shndx,
			 unsigned int sh_type,
			 const unsigned char* prelocs,
			 size_t reloc_count,
			 size_t local_symbol_count,
			 const unsigned char* plocal_symbols,
			 Symbol** global_symbols)
{
  if (sh_type == elfcpp::SHT_RELA)
    {
      gold_error(_("%s: unsupported RELA reloc section"),
		 object->name().c_str());
      return;
    }

  gold::scan_relocs<32, false, Target_i386, elfcpp::SHT_REL,
		    Target_i386::Scan>(
    options,
    symtab,
    layout,
    this,
    object,
    data_shndx,
    prelocs,
    reloc_count,
    local_symbol_count,
    plocal_symbols,
    global_symbols);
}

// Finalize the sections.

void
Target_i386::do_finalize_sections(Layout* layout)
{
  // Fill in some more dynamic tags.
  Output_data_dynamic* const odyn = layout->dynamic_data();
  if (odyn != NULL)
    {
      if (this->got_plt_ != NULL)
	odyn->add_section_address(elfcpp::DT_PLTGOT, this->got_plt_);

      if (this->plt_ != NULL)
	{
	  const Output_data* od = this->plt_->rel_plt();
	  odyn->add_section_size(elfcpp::DT_PLTRELSZ, od);
	  odyn->add_section_address(elfcpp::DT_JMPREL, od);
	  odyn->add_constant(elfcpp::DT_PLTREL, elfcpp::DT_REL);
	}

      if (this->rel_dyn_ != NULL)
	{
	  const Output_data* od = this->rel_dyn_;
	  odyn->add_section_address(elfcpp::DT_REL, od);
	  odyn->add_section_size(elfcpp::DT_RELSZ, od);
	  odyn->add_constant(elfcpp::DT_RELENT,
			     elfcpp::Elf_sizes<32>::rel_size);
	}

      if (!parameters->output_is_shared())
	{
	  // The value of the DT_DEBUG tag is filled in by the dynamic
	  // linker at run time, and used by the debugger.
	  odyn->add_constant(elfcpp::DT_DEBUG, 0);
	}
    }

  // Emit any relocs we saved in an attempt to avoid generating COPY
  // relocs.
  if (this->copy_relocs_ == NULL)
    return;
  if (this->copy_relocs_->any_to_emit())
    {
      Reloc_section* rel_dyn = this->rel_dyn_section(layout);
      this->copy_relocs_->emit(rel_dyn);
    }
  delete this->copy_relocs_;
  this->copy_relocs_ = NULL;
}

// Perform a relocation.

inline bool
Target_i386::Relocate::relocate(const Relocate_info<32, false>* relinfo,
				Target_i386* target,
				size_t relnum,
				const elfcpp::Rel<32, false>& rel,
				unsigned int r_type,
				const Sized_symbol<32>* gsym,
				const Symbol_value<32>* psymval,
				unsigned char* view,
				elfcpp::Elf_types<32>::Elf_Addr address,
				off_t view_size)
{
  if (this->skip_call_tls_get_addr_)
    {
      if (r_type != elfcpp::R_386_PLT32
	  || gsym == NULL
	  || strcmp(gsym->name(), "___tls_get_addr") != 0)
	gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
			       _("missing expected TLS relocation"));
      else
	{
	  this->skip_call_tls_get_addr_ = false;
	  return false;
	}
    }

  // Pick the value to use for symbols defined in shared objects.
  Symbol_value<32> symval;
  if (gsym != NULL && gsym->is_from_dynobj() && gsym->has_plt_offset())
    {
      symval.set_output_value(target->plt_section()->address()
			      + gsym->plt_offset());
      psymval = &symval;
    }

  const Sized_relobj<32, false>* object = relinfo->object;

  switch (r_type)
    {
    case elfcpp::R_386_NONE:
    case elfcpp::R_386_GNU_VTINHERIT:
    case elfcpp::R_386_GNU_VTENTRY:
      break;

    case elfcpp::R_386_32:
      Relocate_functions<32, false>::rel32(view, object, psymval);
      break;

    case elfcpp::R_386_PC32:
      Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
      break;

    case elfcpp::R_386_16:
      Relocate_functions<32, false>::rel16(view, object, psymval);
      break;

    case elfcpp::R_386_PC16:
      Relocate_functions<32, false>::pcrel16(view, object, psymval, address);
      break;

    case elfcpp::R_386_8:
      Relocate_functions<32, false>::rel8(view, object, psymval);
      break;

    case elfcpp::R_386_PC8:
      Relocate_functions<32, false>::pcrel8(view, object, psymval, address);
      break;

    case elfcpp::R_386_PLT32:
      gold_assert(gsym->has_plt_offset()
		  || gsym->final_value_is_known());
      Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
      break;

    case elfcpp::R_386_GOT32:
      // Local GOT offsets not yet supported.
      gold_assert(gsym);
      gold_assert(gsym->has_got_offset());
      Relocate_functions<32, false>::rel32(view, gsym->got_offset());
      break;

    case elfcpp::R_386_GOTOFF:
      {
	elfcpp::Elf_types<32>::Elf_Addr value;
	value = (psymval->value(object, 0)
		 - target->got_section(NULL, NULL)->address());
	Relocate_functions<32, false>::rel32(view, value);
      }
      break;

    case elfcpp::R_386_GOTPC:
      {
	elfcpp::Elf_types<32>::Elf_Addr value;
	value = target->got_section(NULL, NULL)->address();
	Relocate_functions<32, false>::pcrel32(view, value, address);
      }
      break;

    case elfcpp::R_386_COPY:
    case elfcpp::R_386_GLOB_DAT:
    case elfcpp::R_386_JUMP_SLOT:
    case elfcpp::R_386_RELATIVE:
      // These are outstanding tls relocs, which are unexpected when
      // linking.
    case elfcpp::R_386_TLS_TPOFF:
    case elfcpp::R_386_TLS_DTPMOD32:
    case elfcpp::R_386_TLS_DTPOFF32:
    case elfcpp::R_386_TLS_TPOFF32:
    case elfcpp::R_386_TLS_DESC:
      gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
			     _("unexpected reloc %u in object file"),
			     r_type);
      break;

      // These are initial tls relocs, which are expected when
      // linking.
    case elfcpp::R_386_TLS_IE:
    case elfcpp::R_386_TLS_GOTIE:
    case elfcpp::R_386_TLS_LE:
    case elfcpp::R_386_TLS_GD:
    case elfcpp::R_386_TLS_LDM:
    case elfcpp::R_386_TLS_LDO_32:
    case elfcpp::R_386_TLS_IE_32:
    case elfcpp::R_386_TLS_LE_32:
    case elfcpp::R_386_TLS_GOTDESC:
    case elfcpp::R_386_TLS_DESC_CALL:
      this->relocate_tls(relinfo, relnum, rel, r_type, gsym, psymval, view,
			 address, view_size);
      break;

    case elfcpp::R_386_32PLT:
    case elfcpp::R_386_TLS_GD_32:
    case elfcpp::R_386_TLS_GD_PUSH:
    case elfcpp::R_386_TLS_GD_CALL:
    case elfcpp::R_386_TLS_GD_POP:
    case elfcpp::R_386_TLS_LDM_32:
    case elfcpp::R_386_TLS_LDM_PUSH:
    case elfcpp::R_386_TLS_LDM_CALL:
    case elfcpp::R_386_TLS_LDM_POP:
    case elfcpp::R_386_USED_BY_INTEL_200:
    default:
      gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
			     _("unsupported reloc %u"),
			     r_type);
      break;
    }

  return true;
}

// Perform a TLS relocation.

inline void
Target_i386::Relocate::relocate_tls(const Relocate_info<32, false>* relinfo,
				    size_t relnum,
				    const elfcpp::Rel<32, false>& rel,
				    unsigned int r_type,
				    const Sized_symbol<32>* gsym,
				    const Symbol_value<32>* psymval,
				    unsigned char* view,
				    elfcpp::Elf_types<32>::Elf_Addr,
				    off_t view_size)
{
  Output_segment* tls_segment = relinfo->layout->tls_segment();
  if (tls_segment == NULL)
    {
      gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
			     _("TLS reloc but no TLS segment"));
      return;
    }

  elfcpp::Elf_types<32>::Elf_Addr value = psymval->value(relinfo->object, 0);

  const bool is_final = (gsym == NULL
			 ? !parameters->output_is_shared()
			 : gsym->final_value_is_known());
  const tls::Tls_optimization optimized_type
      = Target_i386::optimize_tls_reloc(is_final, r_type);
  switch (r_type)
    {
    case elfcpp::R_386_TLS_LE_32:
      value = tls_segment->vaddr() + tls_segment->memsz() - value;
      Relocate_functions<32, false>::rel32(view, value);
      break;

    case elfcpp::R_386_TLS_LE:
      value = value - (tls_segment->vaddr() + tls_segment->memsz());
      Relocate_functions<32, false>::rel32(view, value);
      break;

    case elfcpp::R_386_TLS_IE:
    case elfcpp::R_386_TLS_GOTIE:
    case elfcpp::R_386_TLS_IE_32:
      if (optimized_type == tls::TLSOPT_TO_LE)
	{
	  Target_i386::Relocate::tls_ie_to_le(relinfo, relnum, tls_segment,
					      rel, r_type, value, view,
					      view_size);
	  break;
	}
      gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
			     _("unsupported reloc %u"),
			     r_type);
      break;

    case elfcpp::R_386_TLS_GD:
      if (optimized_type == tls::TLSOPT_TO_LE)
	{
	  this->tls_gd_to_le(relinfo, relnum, tls_segment,
			     rel, r_type, value, view,
			     view_size);
	  break;
	}
      gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
			     _("unsupported reloc %u"),
			     r_type);
      break;

    case elfcpp::R_386_TLS_LDM:
      if (this->local_dynamic_type_ == LOCAL_DYNAMIC_SUN)
	{
	  gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
				 _("both SUN and GNU model "
				   "TLS relocations"));
	  break;
	}
      this->local_dynamic_type_ = LOCAL_DYNAMIC_GNU;
      if (optimized_type == tls::TLSOPT_TO_LE)
	{
	  this->tls_ld_to_le(relinfo, relnum, tls_segment, rel, r_type,
			     value, view, view_size);
	  break;
	}
      gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
			     _("unsupported reloc %u"),
			     r_type);
      break;

    case elfcpp::R_386_TLS_LDO_32:
      // This reloc can appear in debugging sections, in which case we
      // won't see the TLS_LDM reloc.  The local_dynamic_type field
      // tells us this.
      if (optimized_type != tls::TLSOPT_TO_LE
	  || this->local_dynamic_type_ == LOCAL_DYNAMIC_NONE)
	value = value - tls_segment->vaddr();
      else if (this->local_dynamic_type_ == LOCAL_DYNAMIC_GNU)
	value = value - (tls_segment->vaddr() + tls_segment->memsz());
      else
	value = tls_segment->vaddr() + tls_segment->memsz() - value;
      Relocate_functions<32, false>::rel32(view, value);
      break;

    case elfcpp::R_386_TLS_GOTDESC:
    case elfcpp::R_386_TLS_DESC_CALL:
      gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
			     _("unsupported reloc %u"),
			     r_type);
      break;
    }
}

// Do a relocation in which we convert a TLS Initial-Exec to a
// Local-Exec.

inline void
Target_i386::Relocate::tls_ie_to_le(const Relocate_info<32, false>* relinfo,
				    size_t relnum,
				    Output_segment* tls_segment,
				    const elfcpp::Rel<32, false>& rel,
				    unsigned int r_type,
				    elfcpp::Elf_types<32>::Elf_Addr value,
				    unsigned char* view,
				    off_t view_size)
{
  // We have to actually change the instructions, which means that we
  // need to examine the opcodes to figure out which instruction we
  // are looking at.
  if (r_type == elfcpp::R_386_TLS_IE)
    {
      // movl %gs:XX,%eax  ==>  movl $YY,%eax
      // movl %gs:XX,%reg  ==>  movl $YY,%reg
      // addl %gs:XX,%reg  ==>  addl $YY,%reg
      tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -1);
      tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4);

      unsigned char op1 = view[-1];
      if (op1 == 0xa1)
	{
	  // movl XX,%eax  ==>  movl $YY,%eax
	  view[-1] = 0xb8;
	}
      else
	{
	  tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);

	  unsigned char op2 = view[-2];
	  if (op2 == 0x8b)
	    {
	      // movl XX,%reg  ==>  movl $YY,%reg
	      tls::check_tls(relinfo, relnum, rel.get_r_offset(),
                             (op1 & 0xc7) == 0x05);
	      view[-2] = 0xc7;
	      view[-1] = 0xc0 | ((op1 >> 3) & 7);
	    }
	  else if (op2 == 0x03)
	    {
	      // addl XX,%reg  ==>  addl $YY,%reg
	      tls::check_tls(relinfo, relnum, rel.get_r_offset(),
                             (op1 & 0xc7) == 0x05);
	      view[-2] = 0x81;
	      view[-1] = 0xc0 | ((op1 >> 3) & 7);
	    }
	  else
	    tls::check_tls(relinfo, relnum, rel.get_r_offset(), 0);
	}
    }
  else
    {
      // subl %gs:XX(%reg1),%reg2  ==>  subl $YY,%reg2
      // movl %gs:XX(%reg1),%reg2  ==>  movl $YY,%reg2
      // addl %gs:XX(%reg1),%reg2  ==>  addl $YY,$reg2
      tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
      tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4);

      unsigned char op1 = view[-1];
      unsigned char op2 = view[-2];
      tls::check_tls(relinfo, relnum, rel.get_r_offset(),
                     (op1 & 0xc0) == 0x80 && (op1 & 7) != 4);
      if (op2 == 0x8b)
	{
	  // movl %gs:XX(%reg1),%reg2  ==>  movl $YY,%reg2
	  view[-2] = 0xc7;
	  view[-1] = 0xc0 | ((op1 >> 3) & 7);
	}
      else if (op2 == 0x2b)
	{
	  // subl %gs:XX(%reg1),%reg2  ==>  subl $YY,%reg2
	  view[-2] = 0x81;
	  view[-1] = 0xe8 | ((op1 >> 3) & 7);
	}
      else if (op2 == 0x03)
	{
	  // addl %gs:XX(%reg1),%reg2  ==>  addl $YY,$reg2
	  view[-2] = 0x81;
	  view[-1] = 0xc0 | ((op1 >> 3) & 7);
	}
      else
	tls::check_tls(relinfo, relnum, rel.get_r_offset(), 0);
    }

  value = tls_segment->vaddr() + tls_segment->memsz() - value;
  if (r_type == elfcpp::R_386_TLS_IE || r_type == elfcpp::R_386_TLS_GOTIE)
    value = - value;

  Relocate_functions<32, false>::rel32(view, value);
}

// Do a relocation in which we convert a TLS General-Dynamic to a
// Local-Exec.

inline void
Target_i386::Relocate::tls_gd_to_le(const Relocate_info<32, false>* relinfo,
				    size_t relnum,
				    Output_segment* tls_segment,
				    const elfcpp::Rel<32, false>& rel,
				    unsigned int,
				    elfcpp::Elf_types<32>::Elf_Addr value,
				    unsigned char* view,
				    off_t view_size)
{
  // leal foo(,%reg,1),%eax; call ___tls_get_addr
  //  ==> movl %gs:0,%eax; subl $foo@tpoff,%eax
  // leal foo(%reg),%eax; call ___tls_get_addr
  //  ==> movl %gs:0,%eax; subl $foo@tpoff,%eax

  tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
  tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9);

  unsigned char op1 = view[-1];
  unsigned char op2 = view[-2];

  tls::check_tls(relinfo, relnum, rel.get_r_offset(),
                 op2 == 0x8d || op2 == 0x04);
  tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8);

  int roff = 5;

  if (op2 == 0x04)
    {
      tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -3);
      tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[-3] == 0x8d);
      tls::check_tls(relinfo, relnum, rel.get_r_offset(),
                     ((op1 & 0xc7) == 0x05 && op1 != (4 << 3)));
      memcpy(view - 3, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
    }
  else
    {
      tls::check_tls(relinfo, relnum, rel.get_r_offset(),
                     (op1 & 0xf8) == 0x80 && (op1 & 7) != 4);
      if (static_cast<off_t>(rel.get_r_offset() + 9) < view_size
          && view[9] == 0x90)
	{
	  // There is a trailing nop.  Use the size byte subl.
	  memcpy(view - 2, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
	  roff = 6;
	}
      else
	{
	  // Use the five byte subl.
	  memcpy(view - 2, "\x65\xa1\0\0\0\0\x2d\0\0\0", 11);
	}
    }

  value = tls_segment->vaddr() + tls_segment->memsz() - value;
  Relocate_functions<32, false>::rel32(view + roff, value);

  // The next reloc should be a PLT32 reloc against __tls_get_addr.
  // We can skip it.
  this->skip_call_tls_get_addr_ = true;
}

// Do a relocation in which we convert a TLS Local-Dynamic to a
// Local-Exec.

inline void
Target_i386::Relocate::tls_ld_to_le(const Relocate_info<32, false>* relinfo,
				    size_t relnum,
				    Output_segment*,
				    const elfcpp::Rel<32, false>& rel,
				    unsigned int,
				    elfcpp::Elf_types<32>::Elf_Addr,
				    unsigned char* view,
				    off_t view_size)
{
  // leal foo(%reg), %eax; call ___tls_get_addr
  // ==> movl %gs:0,%eax; nop; leal 0(%esi,1),%esi

  tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
  tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9);

  // FIXME: Does this test really always pass?
  tls::check_tls(relinfo, relnum, rel.get_r_offset(),
                 view[-2] == 0x8d && view[-1] == 0x83);

  tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8);

  memcpy(view - 2, "\x65\xa1\0\0\0\0\x90\x8d\x74\x26\0", 11);

  // The next reloc should be a PLT32 reloc against __tls_get_addr.
  // We can skip it.
  this->skip_call_tls_get_addr_ = true;
}

// Relocate section data.

void
Target_i386::relocate_section(const Relocate_info<32, false>* relinfo,
			      unsigned int sh_type,
			      const unsigned char* prelocs,
			      size_t reloc_count,
			      unsigned char* view,
			      elfcpp::Elf_types<32>::Elf_Addr address,
			      off_t view_size)
{
  gold_assert(sh_type == elfcpp::SHT_REL);

  gold::relocate_section<32, false, Target_i386, elfcpp::SHT_REL,
			 Target_i386::Relocate>(
    relinfo,
    this,
    prelocs,
    reloc_count,
    view,
    address,
    view_size);
}

// Return the value to use for a dynamic which requires special
// treatment.  This is how we support equality comparisons of function
// pointers across shared library boundaries, as described in the
// processor specific ABI supplement.

uint64_t
Target_i386::do_dynsym_value(const Symbol* gsym) const
{
  gold_assert(gsym->is_from_dynobj() && gsym->has_plt_offset());
  return this->plt_section()->address() + gsym->plt_offset();
}

// Return a string used to fill a code section with nops to take up
// the specified length.

std::string
Target_i386::do_code_fill(off_t length)
{
  if (length >= 16)
    {
      // Build a jmp instruction to skip over the bytes.
      unsigned char jmp[5];
      jmp[0] = 0xe9;
      elfcpp::Swap_unaligned<32, false>::writeval(jmp + 1, length - 5);
      return (std::string(reinterpret_cast<char*>(&jmp[0]), 5)
              + std::string(length - 5, '\0'));
    }

  // Nop sequences of various lengths.
  const char nop1[1] = { 0x90 };                   // nop
  const char nop2[2] = { 0x66, 0x90 };             // xchg %ax %ax
  const char nop3[3] = { 0x8d, 0x76, 0x00 };       // leal 0(%esi),%esi
  const char nop4[4] = { 0x8d, 0x74, 0x26, 0x00};  // leal 0(%esi,1),%esi
  const char nop5[5] = { 0x90, 0x8d, 0x74, 0x26,   // nop
                         0x00 };                   // leal 0(%esi,1),%esi
  const char nop6[6] = { 0x8d, 0xb6, 0x00, 0x00,   // leal 0L(%esi),%esi
                         0x00, 0x00 };
  const char nop7[7] = { 0x8d, 0xb4, 0x26, 0x00,   // leal 0L(%esi,1),%esi
                         0x00, 0x00, 0x00 };
  const char nop8[8] = { 0x90, 0x8d, 0xb4, 0x26,   // nop
                         0x00, 0x00, 0x00, 0x00 }; // leal 0L(%esi,1),%esi
  const char nop9[9] = { 0x89, 0xf6, 0x8d, 0xbc,   // movl %esi,%esi
                         0x27, 0x00, 0x00, 0x00,   // leal 0L(%edi,1),%edi
                         0x00 };
  const char nop10[10] = { 0x8d, 0x76, 0x00, 0x8d, // leal 0(%esi),%esi
                           0xbc, 0x27, 0x00, 0x00, // leal 0L(%edi,1),%edi
                           0x00, 0x00 };
  const char nop11[11] = { 0x8d, 0x74, 0x26, 0x00, // leal 0(%esi,1),%esi
                           0x8d, 0xbc, 0x27, 0x00, // leal 0L(%edi,1),%edi
                           0x00, 0x00, 0x00 };
  const char nop12[12] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
                           0x00, 0x00, 0x8d, 0xbf, // leal 0L(%edi),%edi
                           0x00, 0x00, 0x00, 0x00 };
  const char nop13[13] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
                           0x00, 0x00, 0x8d, 0xbc, // leal 0L(%edi,1),%edi
                           0x27, 0x00, 0x00, 0x00,
                           0x00 };
  const char nop14[14] = { 0x8d, 0xb4, 0x26, 0x00, // leal 0L(%esi,1),%esi
                           0x00, 0x00, 0x00, 0x8d, // leal 0L(%edi,1),%edi
                           0xbc, 0x27, 0x00, 0x00,
                           0x00, 0x00 };
  const char nop15[15] = { 0xeb, 0x0d, 0x90, 0x90, // jmp .+15
                           0x90, 0x90, 0x90, 0x90, // nop,nop,nop,...
                           0x90, 0x90, 0x90, 0x90,
                           0x90, 0x90, 0x90 };

  const char* nops[16] = {
    NULL,
    nop1, nop2, nop3, nop4, nop5, nop6, nop7,
    nop8, nop9, nop10, nop11, nop12, nop13, nop14, nop15
  };

  return std::string(nops[length], length);
}

// The selector for i386 object files.

class Target_selector_i386 : public Target_selector
{
public:
  Target_selector_i386()
    : Target_selector(elfcpp::EM_386, 32, false)
  { }

  Target*
  recognize(int machine, int osabi, int abiversion);

 private:
  Target_i386* target_;
};

// Recognize an i386 object file when we already know that the machine
// number is EM_386.

Target*
Target_selector_i386::recognize(int, int, int)
{
  if (this->target_ == NULL)
    this->target_ = new Target_i386();
  return this->target_;
}

Target_selector_i386 target_selector_i386;

} // End anonymous namespace.