aboutsummaryrefslogtreecommitdiff
path: root/gdb/s390-tdep.c
blob: 222743adc7efaa8872416ac2c346b4d4c1579e65 (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
/* Target-dependent code for GDB, the GNU debugger.
   Copyright 2001 Free Software Foundation, Inc.
   Contributed by D.J. Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com)
   for IBM Deutschland Entwicklung GmbH, IBM Corporation.

   This file is part of GDB.

   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 2 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., 59 Temple Place - Suite 330, Boston, MA
   02111-1307, USA.  */

#define S390_TDEP		/* for special macros in tm-s390.h */
#include <defs.h>
#include "arch-utils.h"
#include "frame.h"
#include "inferior.h"
#include "symtab.h"
#include "target.h"
#include "gdbcore.h"
#include "gdbcmd.h"
#include "symfile.h"
#include "objfiles.h"
#include "tm.h"
#include "../bfd/bfd.h"
#include "floatformat.h"
#include "regcache.h"
#include "value.h"





/* Number of bytes of storage in the actual machine representation
   for register N. 
   Note that the unsigned cast here forces the result of the
   subtraction to very high positive values if N < S390_FP0_REGNUM */
int
s390_register_raw_size (int reg_nr)
{
  return ((unsigned) reg_nr - S390_FP0_REGNUM) <
    S390_NUM_FPRS ? S390_FPR_SIZE : 4;
}

int
s390x_register_raw_size (int reg_nr)
{
  return (reg_nr == S390_FPC_REGNUM)
    || (reg_nr >= S390_FIRST_ACR && reg_nr <= S390_LAST_ACR) ? 4 : 8;
}

int
s390_cannot_fetch_register (int regno)
{
  return (regno >= S390_FIRST_CR && regno < (S390_FIRST_CR + 9)) ||
    (regno >= (S390_FIRST_CR + 12) && regno <= S390_LAST_CR);
}

int
s390_register_byte (int reg_nr)
{
  if (reg_nr <= S390_GP_LAST_REGNUM)
    return reg_nr * S390_GPR_SIZE;
  if (reg_nr <= S390_LAST_ACR)
    return S390_ACR0_OFFSET + (((reg_nr) - S390_FIRST_ACR) * S390_ACR_SIZE);
  if (reg_nr <= S390_LAST_CR)
    return S390_CR0_OFFSET + (((reg_nr) - S390_FIRST_CR) * S390_CR_SIZE);
  if (reg_nr == S390_FPC_REGNUM)
    return S390_FPC_OFFSET;
  else
    return S390_FP0_OFFSET + (((reg_nr) - S390_FP0_REGNUM) * S390_FPR_SIZE);
}

#ifndef GDBSERVER
#define S390_MAX_INSTR_SIZE (6)
#define S390_SYSCALL_OPCODE (0x0a)
#define S390_SYSCALL_SIZE   (2)
#define S390_SIGCONTEXT_SREGS_OFFSET (8)
#define S390X_SIGCONTEXT_SREGS_OFFSET (8)
#define S390_SIGREGS_FP0_OFFSET       (144)
#define S390X_SIGREGS_FP0_OFFSET      (216)
#define S390_UC_MCONTEXT_OFFSET    (256)
#define S390X_UC_MCONTEXT_OFFSET   (344)
#define S390_STACK_FRAME_OVERHEAD  (GDB_TARGET_IS_ESAME ? 160:96)
#define S390_SIGNAL_FRAMESIZE  (GDB_TARGET_IS_ESAME ? 160:96)
#define s390_NR_sigreturn          119
#define s390_NR_rt_sigreturn       173



struct frame_extra_info
{
  int initialised;
  int good_prologue;
  CORE_ADDR function_start;
  CORE_ADDR skip_prologue_function_start;
  CORE_ADDR saved_pc_valid;
  CORE_ADDR saved_pc;
  CORE_ADDR sig_fixed_saved_pc_valid;
  CORE_ADDR sig_fixed_saved_pc;
  CORE_ADDR frame_pointer_saved_pc;	/* frame pointer needed for alloca */
  CORE_ADDR stack_bought;	/* amount we decrement the stack pointer by */
  CORE_ADDR sigcontext;
};


static CORE_ADDR s390_frame_saved_pc_nofix (struct frame_info *fi);

int
s390_readinstruction (bfd_byte instr[], CORE_ADDR at,
		      struct disassemble_info *info)
{
  int instrlen;

  static int s390_instrlen[] = {
    2,
    4,
    4,
    6
  };
  if ((*info->read_memory_func) (at, &instr[0], 2, info))
    return -1;
  instrlen = s390_instrlen[instr[0] >> 6];
  if ((*info->read_memory_func) (at + 2, &instr[2], instrlen - 2, info))
    return -1;
  return instrlen;
}

static void
s390_memset_extra_info (struct frame_extra_info *fextra_info)
{
  memset (fextra_info, 0, sizeof (struct frame_extra_info));
}



char *
s390_register_name (int reg_nr)
{
  static char *register_names[] = {
    "pswm", "pswa",
    "gpr0", "gpr1", "gpr2", "gpr3", "gpr4", "gpr5", "gpr6", "gpr7",
    "gpr8", "gpr9", "gpr10", "gpr11", "gpr12", "gpr13", "gpr14", "gpr15",
    "acr0", "acr1", "acr2", "acr3", "acr4", "acr5", "acr6", "acr7",
    "acr8", "acr9", "acr10", "acr11", "acr12", "acr13", "acr14", "acr15",
    "cr0", "cr1", "cr2", "cr3", "cr4", "cr5", "cr6", "cr7",
    "cr8", "cr9", "cr10", "cr11", "cr12", "cr13", "cr14", "cr15",
    "fpc",
    "fpr0", "fpr1", "fpr2", "fpr3", "fpr4", "fpr5", "fpr6", "fpr7",
    "fpr8", "fpr9", "fpr10", "fpr11", "fpr12", "fpr13", "fpr14", "fpr15"
  };

  if (reg_nr >= S390_LAST_REGNUM)
    return NULL;
  return register_names[reg_nr];
}




int
s390_stab_reg_to_regnum (int regno)
{
  return regno >= 64 ? S390_PSWM_REGNUM - 64 :
    regno >= 48 ? S390_FIRST_ACR - 48 :
    regno >= 32 ? S390_FIRST_CR - 32 :
    regno <= 15 ? (regno + 2) :
    S390_FP0_REGNUM + ((regno - 16) & 8) + (((regno - 16) & 3) << 1) +
    (((regno - 16) & 4) >> 2);
}



/* s390_get_frame_info based on Hartmuts
   prologue definition in
   gcc-2.8.1/config/l390/linux.c 

   It reads one instruction at a time & based on whether
   it looks like prologue code or not it makes a decision on
   whether the prologue is over, there are various state machines
   in the code to determine if the prologue code is possilby valid.
   
   This is done to hopefully allow the code survive minor revs of
   calling conventions.

 */

int
s390_get_frame_info (CORE_ADDR pc, struct frame_extra_info *fextra_info,
		     struct frame_info *fi, int init_extra_info)
{
#define CONST_POOL_REGIDX 13
#define GOT_REGIDX        12
  bfd_byte instr[S390_MAX_INSTR_SIZE];
  CORE_ADDR test_pc = pc, test_pc2;
  CORE_ADDR orig_sp = 0, save_reg_addr = 0, *saved_regs = NULL;
  int valid_prologue, good_prologue = 0;
  int gprs_saved[S390_NUM_GPRS];
  int fprs_saved[S390_NUM_FPRS];
  int regidx, instrlen;
  int save_link_regidx, subtract_sp_regidx;
  int const_pool_state, save_link_state, got_state;
  int frame_pointer_found, varargs_state;
  int loop_cnt, gdb_gpr_store, gdb_fpr_store;
  int frame_pointer_regidx = 0xf;
  int offset, expected_offset;
  int err = 0;
  disassemble_info info;
  const_pool_state = save_link_state = got_state = varargs_state = 0;
  frame_pointer_found = 0;
  memset (gprs_saved, 0, sizeof (gprs_saved));
  memset (fprs_saved, 0, sizeof (fprs_saved));
  info.read_memory_func = dis_asm_read_memory;

  save_link_regidx = subtract_sp_regidx = 0;
  if (fextra_info)
    {
      if (fi && fi->frame)
	{
	  orig_sp = fi->frame + fextra_info->stack_bought;
	  saved_regs = fi->saved_regs;
	}
      if (init_extra_info || !fextra_info->initialised)
	{
	  s390_memset_extra_info (fextra_info);
	  fextra_info->function_start = pc;
	  fextra_info->initialised = 1;
	}
    }
  instrlen = 0;
  do
    {
      valid_prologue = 0;
      test_pc += instrlen;
      /* add the previous instruction len */
      instrlen = s390_readinstruction (instr, test_pc, &info);
      if (instrlen < 0)
	{
	  good_prologue = 0;
	  err = -1;
	  break;
	}
      /* We probably are in a glibc syscall */
      if (instr[0] == S390_SYSCALL_OPCODE && test_pc == pc)
	{
	  good_prologue = 1;
	  if (saved_regs && fextra_info && fi->next && fi->next->extra_info
	      && fi->next->extra_info->sigcontext)
	    {
	      /* We are backtracing from a signal handler */
	      save_reg_addr = fi->next->extra_info->sigcontext +
		REGISTER_BYTE (S390_GP0_REGNUM);
	      for (regidx = 0; regidx < S390_NUM_GPRS; regidx++)
		{
		  saved_regs[S390_GP0_REGNUM + regidx] = save_reg_addr;
		  save_reg_addr += S390_GPR_SIZE;
		}
	      save_reg_addr = fi->next->extra_info->sigcontext +
		(GDB_TARGET_IS_ESAME ? S390X_SIGREGS_FP0_OFFSET :
		 S390_SIGREGS_FP0_OFFSET);
	      for (regidx = 0; regidx < S390_NUM_FPRS; regidx++)
		{
		  saved_regs[S390_FP0_REGNUM + regidx] = save_reg_addr;
		  save_reg_addr += S390_FPR_SIZE;
		}
	    }
	  break;
	}
      if (save_link_state == 0)
	{
	  /* check for a stack relative STMG or STM */
	  if (((GDB_TARGET_IS_ESAME &&
		((instr[0] == 0xeb) && (instr[5] == 0x24))) ||
	       (instr[0] == 0x90)) && ((instr[2] >> 4) == 0xf))
	    {
	      regidx = (instr[1] >> 4);
	      if (regidx < 6)
		varargs_state = 1;
	      offset = ((instr[2] & 0xf) << 8) + instr[3];
	      expected_offset =
		S390_GPR6_STACK_OFFSET + (S390_GPR_SIZE * (regidx - 6));
	      if (offset != expected_offset)
		{
		  good_prologue = 0;
		  break;
		}
	      if (saved_regs)
		save_reg_addr = orig_sp + offset;
	      for (; regidx <= (instr[1] & 0xf); regidx++)
		{
		  if (gprs_saved[regidx])
		    {
		      good_prologue = 0;
		      break;
		    }
		  good_prologue = 1;
		  gprs_saved[regidx] = 1;
		  if (saved_regs)
		    {
		      saved_regs[S390_GP0_REGNUM + regidx] = save_reg_addr;
		      save_reg_addr += S390_GPR_SIZE;
		    }
		}
	      valid_prologue = 1;
	      continue;
	    }
	}
      /* check for a stack relative STG or ST */
      if ((save_link_state == 0 || save_link_state == 3) &&
	  ((GDB_TARGET_IS_ESAME &&
	    ((instr[0] == 0xe3) && (instr[5] == 0x24))) ||
	   (instr[0] == 0x50)) && ((instr[2] >> 4) == 0xf))
	{
	  regidx = instr[1] >> 4;
	  offset = ((instr[2] & 0xf) << 8) + instr[3];
	  if (offset == 0)
	    {
	      if (save_link_state == 3 && regidx == save_link_regidx)
		{
		  save_link_state = 4;
		  valid_prologue = 1;
		  continue;
		}
	      else
		break;
	    }
	  if (regidx < 6)
	    varargs_state = 1;
	  expected_offset =
	    S390_GPR6_STACK_OFFSET + (S390_GPR_SIZE * (regidx - 6));
	  if (offset != expected_offset)
	    {
	      good_prologue = 0;
	      break;
	    }
	  if (gprs_saved[regidx])
	    {
	      good_prologue = 0;
	      break;
	    }
	  good_prologue = 1;
	  gprs_saved[regidx] = 1;
	  if (saved_regs)
	    {
	      save_reg_addr = orig_sp + offset;
	      saved_regs[S390_GP0_REGNUM + regidx] = save_reg_addr;
	    }
	  valid_prologue = 1;
	  continue;
	}

      /* check for STD */
      if (instr[0] == 0x60 && (instr[2] >> 4) == 0xf)
	{
	  regidx = instr[1] >> 4;
	  if (regidx == 0 || regidx == 2)
	    varargs_state = 1;
	  if (fprs_saved[regidx])
	    {
	      good_prologue = 0;
	      break;
	    }
	  fprs_saved[regidx] = 1;
	  if (saved_regs)
	    {
	      save_reg_addr = orig_sp + (((instr[2] & 0xf) << 8) + instr[3]);
	      saved_regs[S390_FP0_REGNUM + regidx] = save_reg_addr;
	    }
	  valid_prologue = 1;
	  continue;
	}


      if (const_pool_state == 0)
	{

	  if (GDB_TARGET_IS_ESAME)
	    {
	      /* Check for larl CONST_POOL_REGIDX,offset on ESAME */
	      if ((instr[0] == 0xc0)
		  && (instr[1] == (CONST_POOL_REGIDX << 4)))
		{
		  const_pool_state = 2;
		  valid_prologue = 1;
		  continue;
		}
	    }
	  else
	    {
	      /* Check for BASR gpr13,gpr0 used to load constant pool pointer to r13 in old compiler */
	      if (instr[0] == 0xd && (instr[1] & 0xf) == 0
		  && ((instr[1] >> 4) == CONST_POOL_REGIDX))
		{
		  const_pool_state = 1;
		  valid_prologue = 1;
		  continue;
		}
	    }
	  /* Check for new fangled bras %r13,newpc to load new constant pool */
	  /* embedded in code, older pre abi compilers also emitted this stuff.  */
	  if ((instr[0] == 0xa7) && ((instr[1] & 0xf) == 0x5) &&
	      ((instr[1] >> 4) == CONST_POOL_REGIDX)
	      && ((instr[2] & 0x80) == 0))
	    {
	      const_pool_state = 2;
	      test_pc +=
		(((((instr[2] & 0xf) << 8) + instr[3]) << 1) - instrlen);
	      valid_prologue = 1;
	      continue;
	    }
	}
      /* Check for AGHI or AHI CONST_POOL_REGIDX,val */
      if (const_pool_state == 1 && (instr[0] == 0xa7) &&
	  ((GDB_TARGET_IS_ESAME &&
	    (instr[1] == ((CONST_POOL_REGIDX << 4) | 0xb))) ||
	   (instr[1] == ((CONST_POOL_REGIDX << 4) | 0xa))))
	{
	  const_pool_state = 2;
	  valid_prologue = 1;
	  continue;
	}
      /* Check for LGR or LR gprx,15 */
      if ((GDB_TARGET_IS_ESAME &&
	   instr[0] == 0xb9 && instr[1] == 0x04 && (instr[3] & 0xf) == 0xf) ||
	  (instr[0] == 0x18 && (instr[1] & 0xf) == 0xf))
	{
	  if (GDB_TARGET_IS_ESAME)
	    regidx = instr[3] >> 4;
	  else
	    regidx = instr[1] >> 4;
	  if (save_link_state == 0 && regidx != 0xb)
	    {
	      /* Almost defintely code for
	         decrementing the stack pointer 
	         ( i.e. a non leaf function 
	         or else leaf with locals ) */
	      save_link_regidx = regidx;
	      save_link_state = 1;
	      valid_prologue = 1;
	      continue;
	    }
	  /* We use this frame pointer for alloca
	     unfortunately we need to assume its gpr11
	     otherwise we would need a smarter prologue
	     walker. */
	  if (!frame_pointer_found && regidx == 0xb)
	    {
	      frame_pointer_regidx = 0xb;
	      frame_pointer_found = 1;
	      if (fextra_info)
		fextra_info->frame_pointer_saved_pc = test_pc;
	      valid_prologue = 1;
	      continue;
	    }
	}
      /* Check for AHI or AGHI gpr15,val */
      if (save_link_state == 1 && (instr[0] == 0xa7) &&
	  ((GDB_TARGET_IS_ESAME && (instr[1] == 0xfb)) || (instr[1] == 0xfa)))
	{
	  if (fextra_info)
	    fextra_info->stack_bought =
	      -extract_signed_integer (&instr[2], 2);
	  save_link_state = 3;
	  valid_prologue = 1;
	  continue;
	}
      /* Alternatively check for the complex construction for
         buying more than 32k of stack
         BRAS gprx,.+8
         long vals    %r15,0(%gprx)  gprx currently r1 */
      if ((save_link_state == 1) && (instr[0] == 0xa7)
	  && ((instr[1] & 0xf) == 0x5) && (instr[2] == 0)
	  && (instr[3] == 0x4) && ((instr[1] >> 4) != CONST_POOL_REGIDX))
	{
	  subtract_sp_regidx = instr[1] >> 4;
	  save_link_state = 2;
	  if (fextra_info)
	    target_read_memory (test_pc + instrlen,
				(char *) &fextra_info->stack_bought,
				sizeof (fextra_info->stack_bought));
	  test_pc += 4;
	  valid_prologue = 1;
	  continue;
	}
      if (save_link_state == 2 && instr[0] == 0x5b
	  && instr[1] == 0xf0 &&
	  instr[2] == (subtract_sp_regidx << 4) && instr[3] == 0)
	{
	  save_link_state = 3;
	  valid_prologue = 1;
	  continue;
	}
      /* check for LA gprx,offset(15) used for varargs */
      if ((instr[0] == 0x41) && ((instr[2] >> 4) == 0xf) &&
	  ((instr[1] & 0xf) == 0))
	{
	  /* some code uses gpr7 to point to outgoing args */
	  if (((instr[1] >> 4) == 7) && (save_link_state == 0) &&
	      ((instr[2] & 0xf) == 0)
	      && (instr[3] == S390_STACK_FRAME_OVERHEAD))
	    {
	      valid_prologue = 1;
	      continue;
	    }
	  if (varargs_state == 1)
	    {
	      varargs_state = 2;
	      valid_prologue = 1;
	      continue;
	    }
	}
      /* Check for a GOT load */

      if (GDB_TARGET_IS_ESAME)
	{
	  /* Check for larl  GOT_REGIDX, on ESAME */
	  if ((got_state == 0) && (instr[0] == 0xc0)
	      && (instr[1] == (GOT_REGIDX << 4)))
	    {
	      got_state = 2;
	      valid_prologue = 1;
	      continue;
	    }
	}
      else
	{
	  /* check for l GOT_REGIDX,x(CONST_POOL_REGIDX) */
	  if (got_state == 0 && const_pool_state == 2 && instr[0] == 0x58
	      && (instr[2] == (CONST_POOL_REGIDX << 4))
	      && ((instr[1] >> 4) == GOT_REGIDX))
	    {
	      got_state == 1;
	      valid_prologue = 1;
	      continue;
	    }
	  /* Check for subsequent ar got_regidx,basr_regidx */
	  if (got_state == 1 && instr[0] == 0x1a &&
	      instr[1] == ((GOT_REGIDX << 4) | CONST_POOL_REGIDX))
	    {
	      got_state = 2;
	      valid_prologue = 1;
	      continue;
	    }
	}
    }
  while (valid_prologue && good_prologue);
  if (good_prologue)
    {
      good_prologue = (((got_state == 0) || (got_state == 2)) &&
		       ((const_pool_state == 0) || (const_pool_state == 2)) &&
		       ((save_link_state == 0) || (save_link_state == 4)) &&
		       ((varargs_state == 0) || (varargs_state == 2)));
    }
  if (fextra_info)
    {
      fextra_info->good_prologue = good_prologue;
      fextra_info->skip_prologue_function_start =
	(good_prologue ? test_pc : pc);
    }
  return err;
}


int
s390_check_function_end (CORE_ADDR pc)
{
  bfd_byte instr[S390_MAX_INSTR_SIZE];
  disassemble_info info;
  int regidx, instrlen;

  info.read_memory_func = dis_asm_read_memory;
  instrlen = s390_readinstruction (instr, pc, &info);
  if (instrlen < 0)
    return -1;
  /* check for BR */
  if (instrlen != 2 || instr[0] != 07 || (instr[1] >> 4) != 0xf)
    return 0;
  regidx = instr[1] & 0xf;
  /* Check for LMG or LG */
  instrlen =
    s390_readinstruction (instr, pc - (GDB_TARGET_IS_ESAME ? 6 : 4), &info);
  if (instrlen < 0)
    return -1;
  if (GDB_TARGET_IS_ESAME)
    {

      if (instrlen != 6 || instr[0] != 0xeb || instr[5] != 0x4)
	return 0;
    }
  else if (instrlen != 4 || instr[0] != 0x98)
    {
      return 0;
    }
  if ((instr[2] >> 4) != 0xf)
    return 0;
  if (regidx == 14)
    return 1;
  instrlen = s390_readinstruction (instr, pc - (GDB_TARGET_IS_ESAME ? 12 : 8),
				   &info);
  if (instrlen < 0)
    return -1;
  if (GDB_TARGET_IS_ESAME)
    {
      /* Check for LG */
      if (instrlen != 6 || instr[0] != 0xe3 || instr[5] != 0x4)
	return 0;
    }
  else
    {
      /* Check for L */
      if (instrlen != 4 || instr[0] != 0x58)
	return 0;
    }
  if (instr[2] >> 4 != 0xf)
    return 0;
  if (instr[1] >> 4 != regidx)
    return 0;
  return 1;
}

static CORE_ADDR
s390_sniff_pc_function_start (CORE_ADDR pc, struct frame_info *fi)
{
  CORE_ADDR function_start, test_function_start;
  int loop_cnt, err, function_end;
  struct frame_extra_info fextra_info;
  function_start = get_pc_function_start (pc);

  if (function_start == 0)
    {
      test_function_start = pc;
      if (test_function_start & 1)
	return 0;		/* This has to be bogus */
      loop_cnt = 0;
      do
	{

	  err =
	    s390_get_frame_info (test_function_start, &fextra_info, fi, 1);
	  loop_cnt++;
	  test_function_start -= 2;
	  function_end = s390_check_function_end (test_function_start);
	}
      while (!(function_end == 1 || err || loop_cnt >= 4096 ||
	       (fextra_info.good_prologue)));
      if (fextra_info.good_prologue)
	function_start = fextra_info.function_start;
      else if (function_end == 1)
	function_start = test_function_start;
    }
  return function_start;
}



CORE_ADDR
s390_function_start (struct frame_info *fi)
{
  CORE_ADDR function_start = 0;

  if (fi->extra_info && fi->extra_info->initialised)
    function_start = fi->extra_info->function_start;
  else if (fi->pc)
    function_start = get_pc_function_start (fi->pc);
  return function_start;
}




int
s390_frameless_function_invocation (struct frame_info *fi)
{
  struct frame_extra_info fextra_info, *fextra_info_ptr;
  int frameless = 0;

  if (fi->next == NULL)		/* no may be frameless */
    {
      if (fi->extra_info)
	fextra_info_ptr = fi->extra_info;
      else
	{
	  fextra_info_ptr = &fextra_info;
	  s390_get_frame_info (s390_sniff_pc_function_start (fi->pc, fi),
			       fextra_info_ptr, fi, 1);
	}
      frameless = ((fextra_info_ptr->stack_bought == 0));
    }
  return frameless;

}


static int
s390_is_sigreturn (CORE_ADDR pc, struct frame_info *sighandler_fi,
		   CORE_ADDR *sregs, CORE_ADDR *sigcaller_pc)
{
  bfd_byte instr[S390_MAX_INSTR_SIZE];
  disassemble_info info;
  int instrlen;
  CORE_ADDR scontext;
  int retval = 0;
  CORE_ADDR orig_sp;
  CORE_ADDR temp_sregs;

  scontext = temp_sregs = 0;

  info.read_memory_func = dis_asm_read_memory;
  instrlen = s390_readinstruction (instr, pc, &info);
  if (sigcaller_pc)
    *sigcaller_pc = 0;
  if (((instrlen == S390_SYSCALL_SIZE) &&
       (instr[0] == S390_SYSCALL_OPCODE)) &&
      ((instr[1] == s390_NR_sigreturn) || (instr[1] == s390_NR_rt_sigreturn)))
    {
      if (sighandler_fi)
	{
	  if (s390_frameless_function_invocation (sighandler_fi))
	    orig_sp = sighandler_fi->frame;
	  else
	    orig_sp = ADDR_BITS_REMOVE ((CORE_ADDR)
					read_memory_integer (sighandler_fi->
							     frame,
							     S390_GPR_SIZE));
	  if (orig_sp && sigcaller_pc)
	    {
	      scontext = orig_sp + S390_SIGNAL_FRAMESIZE;
	      if (pc == scontext && instr[1] == s390_NR_rt_sigreturn)
		{
		  /* We got a new style rt_signal */
		  /* get address of read ucontext->uc_mcontext */
		  temp_sregs = orig_sp + (GDB_TARGET_IS_ESAME ?
					  S390X_UC_MCONTEXT_OFFSET :
					  S390_UC_MCONTEXT_OFFSET);
		}
	      else
		{
		  /* read sigcontext->sregs */
		  temp_sregs = ADDR_BITS_REMOVE ((CORE_ADDR)
						 read_memory_integer (scontext
								      +
								      (GDB_TARGET_IS_ESAME
								       ?
								       S390X_SIGCONTEXT_SREGS_OFFSET
								       :
								       S390_SIGCONTEXT_SREGS_OFFSET),
								      S390_GPR_SIZE));

		}
	      /* read sigregs->psw.addr */
	      *sigcaller_pc =
		ADDR_BITS_REMOVE ((CORE_ADDR)
				  read_memory_integer (temp_sregs +
						       REGISTER_BYTE
						       (S390_PC_REGNUM),
						       S390_PSW_ADDR_SIZE));
	    }
	}
      retval = 1;
    }
  if (sregs)
    *sregs = temp_sregs;
  return retval;
}

/*
  We need to do something better here but this will keep us out of trouble
  for the moment.
  For some reason the blockframe.c calls us with fi->next->fromleaf
  so this seems of little use to us. */
void
s390_init_frame_pc_first (int next_fromleaf, struct frame_info *fi)
{
  CORE_ADDR sigcaller_pc;

  fi->pc = 0;
  if (next_fromleaf)
    {
      fi->pc = ADDR_BITS_REMOVE (read_register (S390_RETADDR_REGNUM));
      /* fix signal handlers */
    }
  else if (fi->next && fi->next->pc)
    fi->pc = s390_frame_saved_pc_nofix (fi->next);
  if (fi->pc && fi->next && fi->next->frame &&
      s390_is_sigreturn (fi->pc, fi->next, NULL, &sigcaller_pc))
    {
      fi->pc = sigcaller_pc;
    }

}

void
s390_init_extra_frame_info (int fromleaf, struct frame_info *fi)
{
  fi->extra_info = frame_obstack_alloc (sizeof (struct frame_extra_info));
  if (fi->pc)
    s390_get_frame_info (s390_sniff_pc_function_start (fi->pc, fi),
			 fi->extra_info, fi, 1);
  else
    s390_memset_extra_info (fi->extra_info);
}

/* If saved registers of frame FI are not known yet, read and cache them.
   &FEXTRA_INFOP contains struct frame_extra_info; TDATAP can be NULL,
   in which case the framedata are read.  */

void
s390_frame_init_saved_regs (struct frame_info *fi)
{

  int quick;

  if (fi->saved_regs == NULL)
    {
      /* zalloc memsets the saved regs */
      frame_saved_regs_zalloc (fi);
      if (fi->pc)
	{
	  quick = (fi->extra_info && fi->extra_info->initialised
		   && fi->extra_info->good_prologue);
	  s390_get_frame_info (quick ? fi->extra_info->function_start :
			       s390_sniff_pc_function_start (fi->pc, fi),
			       fi->extra_info, fi, !quick);
	}
    }
}



CORE_ADDR
s390_frame_args_address (struct frame_info *fi)
{

  /* Apparently gdb already knows gdb_args_offset itself */
  return fi->frame;
}


static CORE_ADDR
s390_frame_saved_pc_nofix (struct frame_info *fi)
{
  if (fi->extra_info && fi->extra_info->saved_pc_valid)
    return fi->extra_info->saved_pc;
  s390_frame_init_saved_regs (fi);
  if (fi->extra_info)
    {
      fi->extra_info->saved_pc_valid = 1;
      if (fi->extra_info->good_prologue)
	{
	  if (fi->saved_regs[S390_RETADDR_REGNUM])
	    {
	      return (fi->extra_info->saved_pc =
		      ADDR_BITS_REMOVE (read_memory_integer
					(fi->saved_regs[S390_RETADDR_REGNUM],
					 S390_GPR_SIZE)));
	    }
	}
    }
  return 0;
}

CORE_ADDR
s390_frame_saved_pc (struct frame_info *fi)
{
  CORE_ADDR saved_pc = 0, sig_pc;

  if (fi->extra_info && fi->extra_info->sig_fixed_saved_pc_valid)
    return fi->extra_info->sig_fixed_saved_pc;
  saved_pc = s390_frame_saved_pc_nofix (fi);

  if (fi->extra_info)
    {
      fi->extra_info->sig_fixed_saved_pc_valid = 1;
      if (saved_pc)
	{
	  if (s390_is_sigreturn (saved_pc, fi, NULL, &sig_pc))
	    saved_pc = sig_pc;
	}
      fi->extra_info->sig_fixed_saved_pc = saved_pc;
    }
  return saved_pc;
}




/* We want backtraces out of signal handlers so we don't
   set thisframe->signal_handler_caller to 1 */

CORE_ADDR
s390_frame_chain (struct frame_info *thisframe)
{
  CORE_ADDR prev_fp = 0;

  if (thisframe->prev && thisframe->prev->frame)
    prev_fp = thisframe->prev->frame;
  else
    {
      int sigreturn = 0;
      CORE_ADDR sregs = 0;
      struct frame_extra_info prev_fextra_info;

      memset (&prev_fextra_info, 0, sizeof (prev_fextra_info));
      if (thisframe->pc)
	{
	  CORE_ADDR saved_pc, sig_pc;

	  saved_pc = s390_frame_saved_pc_nofix (thisframe);
	  if (saved_pc)
	    {
	      if ((sigreturn =
		   s390_is_sigreturn (saved_pc, thisframe, &sregs, &sig_pc)))
		saved_pc = sig_pc;
	      s390_get_frame_info (s390_sniff_pc_function_start
				   (saved_pc, NULL), &prev_fextra_info, NULL,
				   1);
	    }
	}
      if (sigreturn)
	{
	  /* read sigregs,regs.gprs[11 or 15] */
	  prev_fp = read_memory_integer (sregs +
					 REGISTER_BYTE (S390_GP0_REGNUM +
							(prev_fextra_info.
							 frame_pointer_saved_pc
							 ? 11 : 15)),
					 S390_GPR_SIZE);
	  thisframe->extra_info->sigcontext = sregs;
	}
      else
	{
	  if (thisframe->saved_regs)
	    {

	      int regno;

	      regno =
		((prev_fextra_info.frame_pointer_saved_pc
		  && thisframe->
		  saved_regs[S390_FRAME_REGNUM]) ? S390_FRAME_REGNUM :
		 S390_SP_REGNUM);
	      if (thisframe->saved_regs[regno])
		prev_fp =
		  read_memory_integer (thisframe->saved_regs[regno],
				       S390_GPR_SIZE);
	    }
	}
    }
  return ADDR_BITS_REMOVE (prev_fp);
}

/*
  Whether struct frame_extra_info is actually needed I'll have to figure
  out as our frames are similar to rs6000 there is a possibility
  i386 dosen't need it. */



/* a given return value in `regbuf' with a type `valtype', extract and copy its
   value into `valbuf' */
void
s390_extract_return_value (struct type *valtype, char *regbuf, char *valbuf)
{
  /* floats and doubles are returned in fpr0. fpr's have a size of 8 bytes.
     We need to truncate the return value into float size (4 byte) if
     necessary. */
  int len = TYPE_LENGTH (valtype);

  if (TYPE_CODE (valtype) == TYPE_CODE_FLT)
    {
      if (len > (TARGET_FLOAT_BIT >> 3))
	memcpy (valbuf, &regbuf[REGISTER_BYTE (S390_FP0_REGNUM)], len);
      else
	{
	  /* float */
	  DOUBLEST val;

	  floatformat_to_doublest (&floatformat_ieee_double_big,
				   &regbuf[REGISTER_BYTE (S390_FP0_REGNUM)],
				   &val);
	  store_floating (valbuf, len, val);
	}
    }
  else
    {
      int offset = 0;
      /* return value is copied starting from r2. */
      if (TYPE_LENGTH (valtype) < S390_GPR_SIZE)
	offset = S390_GPR_SIZE - TYPE_LENGTH (valtype);
      memcpy (valbuf,
	      regbuf + REGISTER_BYTE (S390_GP0_REGNUM + 2) + offset,
	      TYPE_LENGTH (valtype));
    }
}


static char *
s390_promote_integer_argument (struct type *valtype, char *valbuf,
			       char *reg_buff, int *arglen)
{
  char *value = valbuf;
  int len = TYPE_LENGTH (valtype);

  if (len < S390_GPR_SIZE)
    {
      /* We need to upgrade this value to a register to pass it correctly */
      int idx, diff = S390_GPR_SIZE - len, negative =
	(!TYPE_UNSIGNED (valtype) && value[0] & 0x80);
      for (idx = 0; idx < S390_GPR_SIZE; idx++)
	{
	  reg_buff[idx] = (idx < diff ? (negative ? 0xff : 0x0) :
			   value[idx - diff]);
	}
      value = reg_buff;
      *arglen = S390_GPR_SIZE;
    }
  else
    {
      if (len & (S390_GPR_SIZE - 1))
	{
	  fprintf_unfiltered (gdb_stderr,
			      "s390_promote_integer_argument detected an argument not "
			      "a multiple of S390_GPR_SIZE & greater than S390_GPR_SIZE "
			      "we might not deal with this correctly.\n");
	}
      *arglen = len;
    }

  return (value);
}

void
s390_store_return_value (struct type *valtype, char *valbuf)
{
  int arglen;
  char *reg_buff = alloca (max (S390_FPR_SIZE, REGISTER_SIZE)), *value;

  if (TYPE_CODE (valtype) == TYPE_CODE_FLT)
    {
      DOUBLEST tempfloat = extract_floating (valbuf, TYPE_LENGTH (valtype));

      floatformat_from_doublest (&floatformat_ieee_double_big, &tempfloat,
				 reg_buff);
      write_register_bytes (REGISTER_BYTE (S390_FP0_REGNUM), reg_buff,
			    S390_FPR_SIZE);
    }
  else
    {
      value =
	s390_promote_integer_argument (valtype, valbuf, reg_buff, &arglen);
      /* Everything else is returned in GPR2 and up. */
      write_register_bytes (REGISTER_BYTE (S390_GP0_REGNUM + 2), value,
			    arglen);
    }
}
static int
gdb_print_insn_s390 (bfd_vma memaddr, disassemble_info * info)
{
  bfd_byte instrbuff[S390_MAX_INSTR_SIZE];
  int instrlen, cnt;

  instrlen = s390_readinstruction (instrbuff, (CORE_ADDR) memaddr, info);
  if (instrlen < 0)
    {
      (*info->memory_error_func) (instrlen, memaddr, info);
      return -1;
    }
  for (cnt = 0; cnt < instrlen; cnt++)
    info->fprintf_func (info->stream, "%02X ", instrbuff[cnt]);
  for (cnt = instrlen; cnt < S390_MAX_INSTR_SIZE; cnt++)
    info->fprintf_func (info->stream, "   ");
  instrlen = print_insn_s390 (memaddr, info);
  return instrlen;
}



/* Not the most efficent code in the world */
int
s390_fp_regnum ()
{
  int regno = S390_SP_REGNUM;
  struct frame_extra_info fextra_info;

  CORE_ADDR pc = ADDR_BITS_REMOVE (read_register (S390_PC_REGNUM));

  s390_get_frame_info (s390_sniff_pc_function_start (pc, NULL), &fextra_info,
		       NULL, 1);
  if (fextra_info.frame_pointer_saved_pc)
    regno = S390_FRAME_REGNUM;
  return regno;
}

CORE_ADDR
s390_read_fp ()
{
  return read_register (s390_fp_regnum ());
}


void
s390_write_fp (CORE_ADDR val)
{
  write_register (s390_fp_regnum (), val);
}


void
s390_push_dummy_frame ()
{
  CORE_ADDR orig_sp = read_register (S390_SP_REGNUM), new_sp;
  void *saved_regs = alloca (REGISTER_BYTES);

  new_sp = (orig_sp - (REGISTER_BYTES + S390_GPR_SIZE));
  read_register_bytes (0, (char *) saved_regs, REGISTER_BYTES);
  /* Use saved copy instead of orig_sp as this will have the correct endianness */
  write_memory (new_sp, (char *) saved_regs + REGISTER_BYTE (S390_SP_REGNUM),
		S390_GPR_SIZE);
  write_memory (new_sp + S390_GPR_SIZE, (char *) &saved_regs, REGISTER_BYTES);
  write_register (S390_SP_REGNUM, new_sp);
}

/* pop the innermost frame, go back to the caller.
    Used in `call_function_by_hand' to remove an artificial stack
     frame.  */
void
s390_pop_frame ()
{
  CORE_ADDR new_sp = read_register (S390_SP_REGNUM), orig_sp;
  void *saved_regs = alloca (REGISTER_BYTES);


  read_memory (new_sp + S390_GPR_SIZE, (char *) saved_regs, REGISTER_BYTES);
  write_register_bytes (0, (char *) &saved_regs, REGISTER_BYTES);
}

/* used by call function by hand
  struct_return indicates that this function returns a structure &
  therefore gpr2 stores a pointer to the structure to be returned as
  opposed to the first argument.
  Currently I haven't seen a TYPE_CODE_INT whose size wasn't 2^n or less
  than S390_GPR_SIZE this is good because I don't seem to have to worry
  about sign extending pushed arguments (i.e. a signed char currently
  comes into this code with a size of 4 ). */

CORE_ADDR
s390_push_arguments (int nargs, value_ptr *args, CORE_ADDR sp,
		     int struct_return, CORE_ADDR struct_addr)
{
  int num_float_args, num_gpr_args, orig_num_gpr_args, argno;
  int second_pass, len, arglen, gprs_required;
  CORE_ADDR outgoing_args_ptr, outgoing_args_space;
  value_ptr arg;
  struct type *type;
  int max_num_gpr_args = 5 - (struct_return ? 1 : 0);
  int arg0_regnum = S390_GP0_REGNUM + 2 + (struct_return ? 1 : 0);
  char *reg_buff = alloca (max (S390_FPR_SIZE, REGISTER_SIZE)), *value;

  for (second_pass = 0; second_pass <= 1; second_pass++)
    {
      if (second_pass)
	outgoing_args_ptr = sp + S390_STACK_FRAME_OVERHEAD;
      else
	outgoing_args_ptr = 0;
      num_float_args = 0;
      num_gpr_args = 0;
      for (argno = 0; argno < nargs; argno++)
	{
	  arg = args[argno];
	  type = check_typedef (VALUE_TYPE (arg));
	  len = TYPE_LENGTH (type);
	  if (TYPE_CODE (type) == TYPE_CODE_FLT)
	    {
	      int all_float_registers_used =
		num_float_args > (GDB_TARGET_IS_ESAME ? 3 : 1);

	      if (second_pass)
		{
		  DOUBLEST tempfloat =
		    extract_floating (VALUE_CONTENTS (arg), len);


		  floatformat_from_doublest (all_float_registers_used &&
					     len == (TARGET_FLOAT_BIT >> 3)
					     ? &floatformat_ieee_single_big
					     : &floatformat_ieee_double_big,
					     &tempfloat, reg_buff);
		  if (all_float_registers_used)
		    write_memory (outgoing_args_ptr, reg_buff, len);
		  else
		    write_register_bytes (REGISTER_BYTE ((S390_FP0_REGNUM)
							 +
							 (2 *
							  num_float_args)),
					  reg_buff, S390_FPR_SIZE);
		}
	      if (all_float_registers_used)
		outgoing_args_ptr += len;
	      num_float_args++;
	    }
	  else
	    {
	      gprs_required = ((len + (S390_GPR_SIZE - 1)) / S390_GPR_SIZE);

	      value =
		s390_promote_integer_argument (type, VALUE_CONTENTS (arg),
					       reg_buff, &arglen);

	      orig_num_gpr_args = num_gpr_args;
	      num_gpr_args += gprs_required;
	      if (num_gpr_args > max_num_gpr_args)
		{
		  if (second_pass)
		    write_memory (outgoing_args_ptr, value, arglen);
		  outgoing_args_ptr += arglen;
		}
	      else
		{
		  if (second_pass)
		    write_register_bytes (REGISTER_BYTE (arg0_regnum)
					  +
					  (orig_num_gpr_args * S390_GPR_SIZE),
					  value, arglen);
		}
	    }
	}
      if (!second_pass)
	{
	  outgoing_args_space = outgoing_args_ptr;
	  /* Align to 16 bytes because because I like alignment & 
	     some of the kernel code requires 8 byte stack alignment at least. */
	  sp = (sp - (S390_STACK_FRAME_OVERHEAD + outgoing_args_ptr)) & (-16);
	}

    }
  return sp;

}

void
s390_fix_call_dummy (char *dummy, CORE_ADDR pc, CORE_ADDR fun, int nargs,
		     struct value **args, struct type *value_type,
		     int using_gcc)
{
  store_unsigned_integer (dummy + 4, REGISTER_SIZE, fun);
}


/* Return the GDB type object for the "standard" data type
   of data in register N.  */
struct type *
s390_register_virtual_type (int regno)
{
  return ((unsigned) regno - S390_FPC_REGNUM) <
    S390_NUM_FPRS ? builtin_type_double : builtin_type_int;
}


struct type *
s390x_register_virtual_type (int regno)
{
  return (regno == S390_FPC_REGNUM) ||
    (regno >= S390_FIRST_ACR && regno <= S390_LAST_ACR) ? builtin_type_int :
    (regno >= S390_FP0_REGNUM) ? builtin_type_double : builtin_type_long;
}



void
s390_store_struct_return (CORE_ADDR addr, CORE_ADDR sp)
{
  write_register (S390_GP0_REGNUM + 2, addr);
}



static unsigned char *
s390_breakpoint_from_pc (CORE_ADDR *pcptr, int *lenptr)
{
  static unsigned char breakpoint[] = { 0x0, 0x1 };

  *lenptr = sizeof (breakpoint);
  return breakpoint;
}

/* Advance PC across any function entry prologue instructions to reach some
   "real" code.  */
CORE_ADDR
s390_skip_prologue (CORE_ADDR pc)
{
  struct frame_extra_info fextra_info;

  s390_get_frame_info (pc, &fextra_info, NULL, 1);
  return fextra_info.skip_prologue_function_start;
}

/* pc_in_call_dummy_on stack may work for us must test this */
int
s390_pc_in_call_dummy (CORE_ADDR pc, CORE_ADDR sp, CORE_ADDR frame_address)
{
  return pc > sp && pc < (sp + 4096);
}

/* Immediately after a function call, return the saved pc.
   Can't go through the frames for this because on some machines
   the new frame is not set up until the new function executes
   some instructions.  */
CORE_ADDR
s390_saved_pc_after_call (struct frame_info *frame)
{
  return ADDR_BITS_REMOVE (read_register (S390_RETADDR_REGNUM));
}

static CORE_ADDR
s390_addr_bits_remove (CORE_ADDR addr)
{
  return (addr) & 0x7fffffff;
}


static CORE_ADDR
s390_push_return_address (CORE_ADDR pc, CORE_ADDR sp)
{
  return sp;
}

struct gdbarch *
s390_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
{

  /* instruction sequence for s390 call dummy is as follows
     bras %r1,.+8      ; 0xA7150004   
     long basraddr     ; 0x00000000
     l    %r1,0(%r1)   ; 0x58101000
     basr %r14,%r1     ; 0x0DE1
     breakpoint        ; 0x0001 */
  static LONGEST s390_call_dummy_words[] = { 0xA7150004, 0x00000000,
    0x58101000, 0x0DE10001
  };
  /* instruction sequence for esame call dummy is as follows
     bras %r1,.+12     ; 0xA7150006   
     long basraddr     ; 0x0000000000000000
     lg   %r1,0(%r1)   ; 0xE31010000004
     basr %r14,%r1     ; 0x0DE1
     breakpoint        ; 0x0001 */
  static LONGEST s390x_call_dummy_words[] = { 0xA715000600000000,
    0x00000000E3101000,
    0x00040DE100010000
  };
  struct gdbarch *gdbarch;
  struct gdbarch_tdep *tdep;
  int elf_flags;

  /* First see if there is already a gdbarch that can satisfy the request.  */
  arches = gdbarch_list_lookup_by_info (arches, &info);
  if (arches != NULL)
    return arches->gdbarch;

  /* None found: is the request for a s390 architecture? */
  if (info.bfd_arch_info->arch != bfd_arch_s390)
    return NULL;		/* No; then it's not for us.  */

  /* Yes: create a new gdbarch for the specified machine type.  */
  gdbarch = gdbarch_alloc (&info, NULL);

  set_gdbarch_believe_pcc_promotion (gdbarch, 0);

  /* We don't define set_gdbarch_call_dummy_breakpoint_offset 
     as we already have a breakpoint inserted. */
  set_gdbarch_use_generic_dummy_frames (gdbarch, 0);

  set_gdbarch_call_dummy_location (gdbarch, ON_STACK);
  set_gdbarch_call_dummy_start_offset (gdbarch, 0);
  set_gdbarch_pc_in_call_dummy (gdbarch, s390_pc_in_call_dummy);
  set_gdbarch_frame_args_skip (gdbarch, 0);
  set_gdbarch_frame_args_address (gdbarch, s390_frame_args_address);
  set_gdbarch_frame_chain (gdbarch, s390_frame_chain);
  set_gdbarch_frame_init_saved_regs (gdbarch, s390_frame_init_saved_regs);
  set_gdbarch_frame_locals_address (gdbarch, s390_frame_args_address);
  /* We can't do this */
  set_gdbarch_frame_num_args (gdbarch, frame_num_args_unknown);
  set_gdbarch_store_struct_return (gdbarch, s390_store_struct_return);
  set_gdbarch_extract_return_value (gdbarch, s390_extract_return_value);
  set_gdbarch_store_return_value (gdbarch, s390_store_return_value);
  /* Amount PC must be decremented by after a breakpoint.
     This is often the number of bytes in BREAKPOINT
     but not always.  */
  set_gdbarch_decr_pc_after_break (gdbarch, 2);
  set_gdbarch_pop_frame (gdbarch, s390_pop_frame);
  set_gdbarch_push_dummy_frame (gdbarch, s390_push_dummy_frame);
  set_gdbarch_push_arguments (gdbarch, s390_push_arguments);
  set_gdbarch_ieee_float (gdbarch, 1);
  /* Stack grows downward.  */
  set_gdbarch_inner_than (gdbarch, core_addr_lessthan);
  /* Offset from address of function to start of its code.
     Zero on most machines.  */
  set_gdbarch_function_start_offset (gdbarch, 0);
  set_gdbarch_max_register_raw_size (gdbarch, 8);
  set_gdbarch_max_register_virtual_size (gdbarch, 8);
  set_gdbarch_breakpoint_from_pc (gdbarch, s390_breakpoint_from_pc);
  set_gdbarch_skip_prologue (gdbarch, s390_skip_prologue);
  set_gdbarch_init_extra_frame_info (gdbarch, s390_init_extra_frame_info);
  set_gdbarch_init_frame_pc_first (gdbarch, s390_init_frame_pc_first);
  set_gdbarch_read_fp (gdbarch, s390_read_fp);
  set_gdbarch_write_fp (gdbarch, s390_write_fp);
  /* This function that tells us whether the function invocation represented
     by FI does not have a frame on the stack associated with it.  If it
     does not, FRAMELESS is set to 1, else 0.  */
  set_gdbarch_frameless_function_invocation (gdbarch,
					     s390_frameless_function_invocation);
  /* Return saved PC from a frame */
  set_gdbarch_frame_saved_pc (gdbarch, s390_frame_saved_pc);
  /* FRAME_CHAIN takes a frame's nominal address
     and produces the frame's chain-pointer. */
  set_gdbarch_frame_chain (gdbarch, s390_frame_chain);
  set_gdbarch_saved_pc_after_call (gdbarch, s390_saved_pc_after_call);
  set_gdbarch_register_byte (gdbarch, s390_register_byte);
  set_gdbarch_pc_regnum (gdbarch, S390_PC_REGNUM);
  set_gdbarch_sp_regnum (gdbarch, S390_SP_REGNUM);
  set_gdbarch_fp_regnum (gdbarch, S390_FP_REGNUM);
  set_gdbarch_fp0_regnum (gdbarch, S390_FP0_REGNUM);
  set_gdbarch_num_regs (gdbarch, S390_NUM_REGS);
  set_gdbarch_cannot_fetch_register (gdbarch, s390_cannot_fetch_register);
  set_gdbarch_cannot_store_register (gdbarch, s390_cannot_fetch_register);
  set_gdbarch_get_saved_register (gdbarch, generic_get_saved_register);
  set_gdbarch_use_struct_convention (gdbarch, generic_use_struct_convention);
  set_gdbarch_frame_chain_valid (gdbarch, file_frame_chain_valid);
  set_gdbarch_register_name (gdbarch, s390_register_name);
  set_gdbarch_stab_reg_to_regnum (gdbarch, s390_stab_reg_to_regnum);
  set_gdbarch_dwarf_reg_to_regnum (gdbarch, s390_stab_reg_to_regnum);
  set_gdbarch_dwarf2_reg_to_regnum (gdbarch, s390_stab_reg_to_regnum);

  /* Stuff below here wouldn't be required if gdbarch.sh was a little */
  /* more intelligent */
  set_gdbarch_call_dummy_breakpoint_offset_p (gdbarch, 0);
  set_gdbarch_call_dummy_p (gdbarch, 1);
  set_gdbarch_call_dummy_stack_adjust_p (gdbarch, 0);
  set_gdbarch_extract_struct_value_address (gdbarch, 0);
  set_gdbarch_fix_call_dummy (gdbarch, s390_fix_call_dummy);
#ifdef GDB_NM_FILE
  set_gdbarch_prepare_to_proceed (gdbarch, linuxthreads_prepare_to_proceed);
#endif
  set_gdbarch_push_return_address (gdbarch, s390_push_return_address);

  switch (info.bfd_arch_info->mach)
    {
    case bfd_mach_s390_esa:
      set_gdbarch_register_size (gdbarch, 4);
      set_gdbarch_call_dummy_length (gdbarch, 16);
      set_gdbarch_register_raw_size (gdbarch, s390_register_raw_size);
      set_gdbarch_register_virtual_size (gdbarch, s390_register_raw_size);
      set_gdbarch_register_virtual_type (gdbarch, s390_register_virtual_type);

      set_gdbarch_addr_bits_remove (gdbarch, s390_addr_bits_remove);

      set_gdbarch_sizeof_call_dummy_words (gdbarch,
					   sizeof (s390_call_dummy_words));
      set_gdbarch_call_dummy_words (gdbarch, s390_call_dummy_words);
      set_gdbarch_register_bytes (gdbarch, S390_REGISTER_BYTES);
      break;
    case bfd_mach_s390_esame:
      set_gdbarch_register_size (gdbarch, 8);
      set_gdbarch_call_dummy_length (gdbarch, 22);
      set_gdbarch_register_raw_size (gdbarch, s390x_register_raw_size);
      set_gdbarch_register_virtual_size (gdbarch, s390x_register_raw_size);
      set_gdbarch_register_virtual_type (gdbarch,
					 s390x_register_virtual_type);

      set_gdbarch_long_bit (gdbarch, 64);
      set_gdbarch_long_long_bit (gdbarch, 64);
      set_gdbarch_ptr_bit (gdbarch, 64);
      set_gdbarch_sizeof_call_dummy_words (gdbarch,
					   sizeof (s390x_call_dummy_words));
      set_gdbarch_call_dummy_words (gdbarch, s390x_call_dummy_words);
      set_gdbarch_register_bytes (gdbarch, S390X_REGISTER_BYTES);
      break;
    }

  return gdbarch;
}



void
_initialize_s390_tdep ()
{

  /* Hook us into the gdbarch mechanism.  */
  register_gdbarch_init (bfd_arch_s390, s390_gdbarch_init);
  if (!tm_print_insn)		/* Someone may have already set it */
    tm_print_insn = gdb_print_insn_s390;
}

#endif /* GDBSERVER */