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
|
/* Target-dependent code for GDB, the GNU debugger.
Copyright 1986, 1987, 1989, 1991, 1992, 1993, 1994, 1995
Free Software Foundation, Inc.
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., 675 Mass Ave, Cambridge, MA 02139, USA. */
#include "defs.h"
#include "frame.h"
#include "inferior.h"
#include "symtab.h"
#include "target.h"
#include "gdbcore.h"
#include "xcoffsolib.h"
#include <a.out.h>
extern struct obstack frame_cache_obstack;
extern int errno;
/* Nonzero if we just simulated a single step break. */
int one_stepped;
/* Breakpoint shadows for the single step instructions will be kept here. */
static struct sstep_breaks {
/* Address, or 0 if this is not in use. */
CORE_ADDR address;
/* Shadow contents. */
char data[4];
} stepBreaks[2];
/* Static function prototypes */
static CORE_ADDR
find_toc_address PARAMS ((CORE_ADDR pc));
static CORE_ADDR
branch_dest PARAMS ((int opcode, int instr, CORE_ADDR pc, CORE_ADDR safety));
static void
frame_get_cache_fsr PARAMS ((struct frame_info *fi,
struct aix_framedata *fdatap));
/*
* Calculate the destination of a branch/jump. Return -1 if not a branch.
*/
static CORE_ADDR
branch_dest (opcode, instr, pc, safety)
int opcode;
int instr;
CORE_ADDR pc;
CORE_ADDR safety;
{
register long offset;
CORE_ADDR dest;
int immediate;
int absolute;
int ext_op;
absolute = (int) ((instr >> 1) & 1);
switch (opcode) {
case 18 :
immediate = ((instr & ~3) << 6) >> 6; /* br unconditional */
if (absolute)
dest = immediate;
else
dest = pc + immediate;
break;
case 16 :
immediate = ((instr & ~3) << 16) >> 16; /* br conditional */
if (absolute)
dest = immediate;
else
dest = pc + immediate;
break;
case 19 :
ext_op = (instr>>1) & 0x3ff;
if (ext_op == 16) /* br conditional register */
dest = read_register (LR_REGNUM) & ~3;
else if (ext_op == 528) /* br cond to count reg */
{
dest = read_register (CTR_REGNUM) & ~3;
/* If we are about to execute a system call, dest is something
like 0x22fc or 0x3b00. Upon completion the system call
will return to the address in the link register. */
if (dest < TEXT_SEGMENT_BASE)
dest = read_register (LR_REGNUM) & ~3;
}
else return -1;
break;
default: return -1;
}
return (dest < TEXT_SEGMENT_BASE) ? safety : dest;
}
/* AIX does not support PT_STEP. Simulate it. */
void
single_step (signal)
int signal;
{
#define INSNLEN(OPCODE) 4
static char breakp[] = BREAKPOINT;
int ii, insn;
CORE_ADDR loc;
CORE_ADDR breaks[2];
int opcode;
if (!one_stepped) {
loc = read_pc ();
insn = read_memory_integer (loc, 4);
breaks[0] = loc + INSNLEN(insn);
opcode = insn >> 26;
breaks[1] = branch_dest (opcode, insn, loc, breaks[0]);
/* Don't put two breakpoints on the same address. */
if (breaks[1] == breaks[0])
breaks[1] = -1;
stepBreaks[1].address = 0;
for (ii=0; ii < 2; ++ii) {
/* ignore invalid breakpoint. */
if ( breaks[ii] == -1)
continue;
read_memory (breaks[ii], stepBreaks[ii].data, 4);
write_memory (breaks[ii], breakp, 4);
stepBreaks[ii].address = breaks[ii];
}
one_stepped = 1;
} else {
/* remove step breakpoints. */
for (ii=0; ii < 2; ++ii)
if (stepBreaks[ii].address != 0)
write_memory
(stepBreaks[ii].address, stepBreaks[ii].data, 4);
one_stepped = 0;
}
errno = 0; /* FIXME, don't ignore errors! */
/* What errors? {read,write}_memory call error(). */
}
/* return pc value after skipping a function prologue. */
skip_prologue (pc)
CORE_ADDR pc;
{
char buf[4];
unsigned int tmp;
unsigned long op;
if (target_read_memory (pc, buf, 4))
return pc; /* Can't access it -- assume no prologue. */
op = extract_unsigned_integer (buf, 4);
/* Assume that subsequent fetches can fail with low probability. */
if (op == 0x7c0802a6) { /* mflr r0 */
pc += 4;
op = read_memory_integer (pc, 4);
}
if ((op & 0xfc00003e) == 0x7c000026) { /* mfcr Rx */
pc += 4;
op = read_memory_integer (pc, 4);
}
if ((op & 0xfc000000) == 0x48000000) { /* bl foo, to save fprs??? */
pc += 4;
op = read_memory_integer (pc, 4);
/* At this point, make sure this is not a trampoline function
(a function that simply calls another functions, and nothing else).
If the next is not a nop, this branch was part of the function
prologue. */
if (op == 0x4def7b82 || /* crorc 15, 15, 15 */
op == 0x0)
return pc - 4; /* don't skip over this branch */
}
if ((op & 0xfc1f0000) == 0xd8010000) { /* stfd Rx,NUM(r1) */
pc += 4; /* store floating register double */
op = read_memory_integer (pc, 4);
}
if ((op & 0xfc1f0000) == 0xbc010000) { /* stm Rx, NUM(r1) */
pc += 4;
op = read_memory_integer (pc, 4);
}
while (((tmp = op >> 16) == 0x9001) || /* st r0, NUM(r1) */
(tmp == 0x9421) || /* stu r1, NUM(r1) */
(tmp == 0x93e1)) /* st r31,NUM(r1) */
{
pc += 4;
op = read_memory_integer (pc, 4);
}
while ((tmp = (op >> 22)) == 0x20f) { /* l r31, ... or */
pc += 4; /* l r30, ... */
op = read_memory_integer (pc, 4);
}
/* store parameters into stack */
while(
(op & 0xfc1f0000) == 0xd8010000 || /* stfd Rx,NUM(r1) */
(op & 0xfc1f0000) == 0x90010000 || /* st r?, NUM(r1) */
(op & 0xfc000000) == 0xfc000000 || /* frsp, fp?, .. */
(op & 0xd0000000) == 0xd0000000) /* stfs, fp?, .. */
{
pc += 4; /* store fpr double */
op = read_memory_integer (pc, 4);
}
if (op == 0x603f0000 /* oril r31, r1, 0x0 */
|| op == 0x7c3f0b78) { /* mr r31, r1 */
pc += 4; /* this happens if r31 is used as */
op = read_memory_integer (pc, 4); /* frame ptr. (gcc does that) */
tmp = 0;
while ((op >> 16) == (0x907f + tmp)) { /* st r3, NUM(r31) */
pc += 4; /* st r4, NUM(r31), ... */
op = read_memory_integer (pc, 4);
tmp += 0x20;
}
}
#if 0
/* I have problems with skipping over __main() that I need to address
* sometime. Previously, I used to use misc_function_vector which
* didn't work as well as I wanted to be. -MGO */
/* If the first thing after skipping a prolog is a branch to a function,
this might be a call to an initializer in main(), introduced by gcc2.
We'd like to skip over it as well. Fortunately, xlc does some extra
work before calling a function right after a prologue, thus we can
single out such gcc2 behaviour. */
if ((op & 0xfc000001) == 0x48000001) { /* bl foo, an initializer function? */
op = read_memory_integer (pc+4, 4);
if (op == 0x4def7b82) { /* cror 0xf, 0xf, 0xf (nop) */
/* check and see if we are in main. If so, skip over this initializer
function as well. */
tmp = find_pc_misc_function (pc);
if (tmp >= 0 && STREQ (misc_function_vector [tmp].name, "main"))
return pc + 8;
}
}
#endif /* 0 */
return pc;
}
/*************************************************************************
Support for creating pushind a dummy frame into the stack, and popping
frames, etc.
*************************************************************************/
/* The total size of dummy frame is 436, which is;
32 gpr's - 128 bytes
32 fpr's - 256 "
7 the rest - 28 "
and 24 extra bytes for the callee's link area. The last 24 bytes
for the link area might not be necessary, since it will be taken
care of by push_arguments(). */
#define DUMMY_FRAME_SIZE 436
#define DUMMY_FRAME_ADDR_SIZE 10
/* Make sure you initialize these in somewhere, in case gdb gives up what it
was debugging and starts debugging something else. FIXMEibm */
static int dummy_frame_count = 0;
static int dummy_frame_size = 0;
static CORE_ADDR *dummy_frame_addr = 0;
extern int stop_stack_dummy;
/* push a dummy frame into stack, save all register. Currently we are saving
only gpr's and fpr's, which is not good enough! FIXMEmgo */
void
push_dummy_frame ()
{
/* stack pointer. */
CORE_ADDR sp;
/* Same thing, target byte order. */
char sp_targ[4];
/* link register. */
CORE_ADDR pc;
/* Same thing, target byte order. */
char pc_targ[4];
int ii;
target_fetch_registers (-1);
if (dummy_frame_count >= dummy_frame_size) {
dummy_frame_size += DUMMY_FRAME_ADDR_SIZE;
if (dummy_frame_addr)
dummy_frame_addr = (CORE_ADDR*) xrealloc
(dummy_frame_addr, sizeof(CORE_ADDR) * (dummy_frame_size));
else
dummy_frame_addr = (CORE_ADDR*)
xmalloc (sizeof(CORE_ADDR) * (dummy_frame_size));
}
sp = read_register(SP_REGNUM);
pc = read_register(PC_REGNUM);
store_address (pc, 4, pc_targ);
dummy_frame_addr [dummy_frame_count++] = sp;
/* Be careful! If the stack pointer is not decremented first, then kernel
thinks he is free to use the space underneath it. And kernel actually
uses that area for IPC purposes when executing ptrace(2) calls. So
before writing register values into the new frame, decrement and update
%sp first in order to secure your frame. */
write_register (SP_REGNUM, sp-DUMMY_FRAME_SIZE);
/* gdb relies on the state of current_frame. We'd better update it,
otherwise things like do_registers_info() wouldn't work properly! */
flush_cached_frames ();
/* save program counter in link register's space. */
write_memory (sp+8, pc_targ, 4);
/* save all floating point and general purpose registers here. */
/* fpr's, f0..f31 */
for (ii = 0; ii < 32; ++ii)
write_memory (sp-8-(ii*8), ®isters[REGISTER_BYTE (31-ii+FP0_REGNUM)], 8);
/* gpr's r0..r31 */
for (ii=1; ii <=32; ++ii)
write_memory (sp-256-(ii*4), ®isters[REGISTER_BYTE (32-ii)], 4);
/* so far, 32*2 + 32 words = 384 bytes have been written.
7 extra registers in our register set: pc, ps, cnd, lr, cnt, xer, mq */
for (ii=1; ii <= (LAST_SP_REGNUM-FIRST_SP_REGNUM+1); ++ii) {
write_memory (sp-384-(ii*4),
®isters[REGISTER_BYTE (FPLAST_REGNUM + ii)], 4);
}
/* Save sp or so called back chain right here. */
store_address (sp_targ, 4, sp);
write_memory (sp-DUMMY_FRAME_SIZE, sp_targ, 4);
sp -= DUMMY_FRAME_SIZE;
/* And finally, this is the back chain. */
write_memory (sp+8, pc_targ, 4);
}
/* Pop a dummy frame.
In rs6000 when we push a dummy frame, we save all of the registers. This
is usually done before user calls a function explicitly.
After a dummy frame is pushed, some instructions are copied into stack,
and stack pointer is decremented even more. Since we don't have a frame
pointer to get back to the parent frame of the dummy, we start having
trouble poping it. Therefore, we keep a dummy frame stack, keeping
addresses of dummy frames as such. When poping happens and when we
detect that was a dummy frame, we pop it back to its parent by using
dummy frame stack (`dummy_frame_addr' array).
FIXME: This whole concept is broken. You should be able to detect
a dummy stack frame *on the user's stack itself*. When you do,
then you know the format of that stack frame -- including its
saved SP register! There should *not* be a separate stack in the
GDB process that keeps track of these dummy frames! -- gnu@cygnus.com Aug92
*/
pop_dummy_frame ()
{
CORE_ADDR sp, pc;
int ii;
sp = dummy_frame_addr [--dummy_frame_count];
/* restore all fpr's. */
for (ii = 1; ii <= 32; ++ii)
read_memory (sp-(ii*8), ®isters[REGISTER_BYTE (32-ii+FP0_REGNUM)], 8);
/* restore all gpr's */
for (ii=1; ii <= 32; ++ii) {
read_memory (sp-256-(ii*4), ®isters[REGISTER_BYTE (32-ii)], 4);
}
/* restore the rest of the registers. */
for (ii=1; ii <=(LAST_SP_REGNUM-FIRST_SP_REGNUM+1); ++ii)
read_memory (sp-384-(ii*4),
®isters[REGISTER_BYTE (FPLAST_REGNUM + ii)], 4);
read_memory (sp-(DUMMY_FRAME_SIZE-8),
®isters [REGISTER_BYTE(PC_REGNUM)], 4);
/* when a dummy frame was being pushed, we had to decrement %sp first, in
order to secure astack space. Thus, saved %sp (or %r1) value, is not the
one we should restore. Change it with the one we need. */
*(int*)®isters [REGISTER_BYTE(FP_REGNUM)] = sp;
/* Now we can restore all registers. */
target_store_registers (-1);
pc = read_pc ();
flush_cached_frames ();
}
/* pop the innermost frame, go back to the caller. */
void
pop_frame ()
{
CORE_ADDR pc, lr, sp, prev_sp; /* %pc, %lr, %sp */
struct aix_framedata fdata;
struct frame_info *frame = get_current_frame ();
int addr, ii;
pc = read_pc ();
sp = FRAME_FP (frame);
if (stop_stack_dummy && dummy_frame_count) {
pop_dummy_frame ();
return;
}
/* Make sure that all registers are valid. */
read_register_bytes (0, NULL, REGISTER_BYTES);
/* figure out previous %pc value. If the function is frameless, it is
still in the link register, otherwise walk the frames and retrieve the
saved %pc value in the previous frame. */
addr = get_pc_function_start (frame->pc) + FUNCTION_START_OFFSET;
function_frame_info (addr, &fdata);
if (fdata.frameless)
prev_sp = sp;
else
prev_sp = read_memory_integer (sp, 4);
if (fdata.nosavedpc)
lr = read_register (LR_REGNUM);
else
lr = read_memory_integer (prev_sp+8, 4);
/* reset %pc value. */
write_register (PC_REGNUM, lr);
/* reset register values if any was saved earlier. */
addr = prev_sp - fdata.offset;
if (fdata.saved_gpr != -1)
for (ii = fdata.saved_gpr; ii <= 31; ++ii) {
read_memory (addr, ®isters [REGISTER_BYTE (ii)], 4);
addr += 4;
}
if (fdata.saved_fpr != -1)
for (ii = fdata.saved_fpr; ii <= 31; ++ii) {
read_memory (addr, ®isters [REGISTER_BYTE (ii+FP0_REGNUM)], 8);
addr += 8;
}
write_register (SP_REGNUM, prev_sp);
target_store_registers (-1);
flush_cached_frames ();
}
/* fixup the call sequence of a dummy function, with the real function address.
its argumets will be passed by gdb. */
void
fix_call_dummy(dummyname, pc, fun, nargs, type)
char *dummyname;
CORE_ADDR pc;
CORE_ADDR fun;
int nargs; /* not used */
int type; /* not used */
{
#define TOC_ADDR_OFFSET 20
#define TARGET_ADDR_OFFSET 28
int ii;
CORE_ADDR target_addr;
CORE_ADDR tocvalue;
target_addr = fun;
tocvalue = find_toc_address (target_addr);
ii = *(int*)((char*)dummyname + TOC_ADDR_OFFSET);
ii = (ii & 0xffff0000) | (tocvalue >> 16);
*(int*)((char*)dummyname + TOC_ADDR_OFFSET) = ii;
ii = *(int*)((char*)dummyname + TOC_ADDR_OFFSET+4);
ii = (ii & 0xffff0000) | (tocvalue & 0x0000ffff);
*(int*)((char*)dummyname + TOC_ADDR_OFFSET+4) = ii;
ii = *(int*)((char*)dummyname + TARGET_ADDR_OFFSET);
ii = (ii & 0xffff0000) | (target_addr >> 16);
*(int*)((char*)dummyname + TARGET_ADDR_OFFSET) = ii;
ii = *(int*)((char*)dummyname + TARGET_ADDR_OFFSET+4);
ii = (ii & 0xffff0000) | (target_addr & 0x0000ffff);
*(int*)((char*)dummyname + TARGET_ADDR_OFFSET+4) = ii;
}
/* return information about a function frame.
in struct aix_frameinfo fdata:
- frameless is TRUE, if function does not have a frame.
- nosavedpc is TRUE, if function does not save %pc value in its frame.
- offset is the number of bytes used in the frame to save registers.
- saved_gpr is the number of the first saved gpr.
- saved_fpr is the number of the first saved fpr.
- alloca_reg is the number of the register used for alloca() handling.
Otherwise -1.
*/
void
function_frame_info (pc, fdata)
CORE_ADDR pc;
struct aix_framedata *fdata;
{
unsigned int tmp;
register unsigned int op;
char buf[4];
fdata->offset = 0;
fdata->saved_gpr = fdata->saved_fpr = fdata->alloca_reg = -1;
fdata->frameless = 1;
/* Do not error out if we can't access the instructions. */
if (target_read_memory (pc, buf, 4))
return;
op = extract_unsigned_integer (buf, 4);
if (op == 0x7c0802a6) { /* mflr r0 */
pc += 4;
op = read_memory_integer (pc, 4);
fdata->nosavedpc = 0;
fdata->frameless = 0;
}
else /* else, pc is not saved */
fdata->nosavedpc = 1;
if ((op & 0xfc00003e) == 0x7c000026) { /* mfcr Rx */
pc += 4;
op = read_memory_integer (pc, 4);
fdata->frameless = 0;
}
if ((op & 0xfc000000) == 0x48000000) { /* bl foo, to save fprs??? */
pc += 4;
op = read_memory_integer (pc, 4);
/* At this point, make sure this is not a trampoline function
(a function that simply calls another functions, and nothing else).
If the next is not a nop, this branch was part of the function
prologue. */
if (op == 0x4def7b82 || /* crorc 15, 15, 15 */
op == 0x0)
return; /* prologue is over */
fdata->frameless = 0;
}
if ((op & 0xfc1f0000) == 0xd8010000) { /* stfd Rx,NUM(r1) */
pc += 4; /* store floating register double */
op = read_memory_integer (pc, 4);
fdata->frameless = 0;
}
if ((op & 0xfc1f0000) == 0xbc010000) { /* stm Rx, NUM(r1) */
int tmp2;
fdata->saved_gpr = (op >> 21) & 0x1f;
tmp2 = op & 0xffff;
if (tmp2 > 0x7fff)
tmp2 = (~0 &~ 0xffff) | tmp2;
if (tmp2 < 0) {
tmp2 = tmp2 * -1;
fdata->saved_fpr = (tmp2 - ((32 - fdata->saved_gpr) * 4)) / 8;
if ( fdata->saved_fpr > 0)
fdata->saved_fpr = 32 - fdata->saved_fpr;
else
fdata->saved_fpr = -1;
}
fdata->offset = tmp2;
pc += 4;
op = read_memory_integer (pc, 4);
fdata->frameless = 0;
}
while (((tmp = op >> 16) == 0x9001) || /* st r0, NUM(r1) */
(tmp == 0x9421) || /* stu r1, NUM(r1) */
(tmp == 0x93e1)) /* st r31, NUM(r1) */
{
int tmp2;
/* gcc takes a short cut and uses this instruction to save r31 only. */
if (tmp == 0x93e1) {
if (fdata->offset)
/* fatal ("Unrecognized prolog."); */
printf_unfiltered ("Unrecognized prolog!\n");
fdata->saved_gpr = 31;
tmp2 = op & 0xffff;
if (tmp2 > 0x7fff) {
tmp2 = - ((~0 &~ 0xffff) | tmp2);
fdata->saved_fpr = (tmp2 - ((32 - 31) * 4)) / 8;
if ( fdata->saved_fpr > 0)
fdata->saved_fpr = 32 - fdata->saved_fpr;
else
fdata->saved_fpr = -1;
}
fdata->offset = tmp2;
}
pc += 4;
op = read_memory_integer (pc, 4);
fdata->frameless = 0;
}
while ((tmp = (op >> 22)) == 0x20f) { /* l r31, ... or */
pc += 4; /* l r30, ... */
op = read_memory_integer (pc, 4);
fdata->frameless = 0;
}
/* store parameters into stack */
while(
(op & 0xfc1f0000) == 0xd8010000 || /* stfd Rx,NUM(r1) */
(op & 0xfc1f0000) == 0x90010000 || /* st r?, NUM(r1) */
(op & 0xfc000000) == 0xfc000000 || /* frsp, fp?, .. */
(op & 0xd0000000) == 0xd0000000) /* stfs, fp?, .. */
{
pc += 4; /* store fpr double */
op = read_memory_integer (pc, 4);
fdata->frameless = 0;
}
if (op == 0x603f0000 /* oril r31, r1, 0x0 */
|| op == 0x7c3f0b78) /* mr r31, r1 */
{
fdata->alloca_reg = 31;
fdata->frameless = 0;
}
}
/* Pass the arguments in either registers, or in the stack. In RS6000, the first
eight words of the argument list (that might be less than eight parameters if
some parameters occupy more than one word) are passed in r3..r11 registers.
float and double parameters are passed in fpr's, in addition to that. Rest of
the parameters if any are passed in user stack. There might be cases in which
half of the parameter is copied into registers, the other half is pushed into
stack.
If the function is returning a structure, then the return address is passed
in r3, then the first 7 words of the parametes can be passed in registers,
starting from r4. */
CORE_ADDR
push_arguments (nargs, args, sp, struct_return, struct_addr)
int nargs;
value_ptr *args;
CORE_ADDR sp;
int struct_return;
CORE_ADDR struct_addr;
{
int ii, len;
int argno; /* current argument number */
int argbytes; /* current argument byte */
char tmp_buffer [50];
value_ptr arg;
int f_argno = 0; /* current floating point argno */
CORE_ADDR saved_sp, pc;
if ( dummy_frame_count <= 0)
printf_unfiltered ("FATAL ERROR -push_arguments()! frame not found!!\n");
/* The first eight words of ther arguments are passed in registers. Copy
them appropriately.
If the function is returning a `struct', then the first word (which
will be passed in r3) is used for struct return address. In that
case we should advance one word and start from r4 register to copy
parameters. */
ii = struct_return ? 1 : 0;
for (argno=0, argbytes=0; argno < nargs && ii<8; ++ii) {
arg = args[argno];
len = TYPE_LENGTH (VALUE_TYPE (arg));
if (TYPE_CODE (VALUE_TYPE (arg)) == TYPE_CODE_FLT) {
/* floating point arguments are passed in fpr's, as well as gpr's.
There are 13 fpr's reserved for passing parameters. At this point
there is no way we would run out of them. */
if (len > 8)
printf_unfiltered (
"Fatal Error: a floating point parameter #%d with a size > 8 is found!\n", argno);
memcpy (®isters[REGISTER_BYTE(FP0_REGNUM + 1 + f_argno)], VALUE_CONTENTS (arg),
len);
++f_argno;
}
if (len > 4) {
/* Argument takes more than one register. */
while (argbytes < len) {
*(int*)®isters[REGISTER_BYTE(ii+3)] = 0;
memcpy (®isters[REGISTER_BYTE(ii+3)],
((char*)VALUE_CONTENTS (arg))+argbytes,
(len - argbytes) > 4 ? 4 : len - argbytes);
++ii, argbytes += 4;
if (ii >= 8)
goto ran_out_of_registers_for_arguments;
}
argbytes = 0;
--ii;
}
else { /* Argument can fit in one register. No problem. */
*(int*)®isters[REGISTER_BYTE(ii+3)] = 0;
memcpy (®isters[REGISTER_BYTE(ii+3)], VALUE_CONTENTS (arg), len);
}
++argno;
}
ran_out_of_registers_for_arguments:
/* location for 8 parameters are always reserved. */
sp -= 4 * 8;
/* another six words for back chain, TOC register, link register, etc. */
sp -= 24;
/* if there are more arguments, allocate space for them in
the stack, then push them starting from the ninth one. */
if ((argno < nargs) || argbytes) {
int space = 0, jj;
value_ptr val;
if (argbytes) {
space += ((len - argbytes + 3) & -4);
jj = argno + 1;
}
else
jj = argno;
for (; jj < nargs; ++jj) {
val = args[jj];
space += ((TYPE_LENGTH (VALUE_TYPE (val))) + 3) & -4;
}
/* add location required for the rest of the parameters */
space = (space + 7) & -8;
sp -= space;
/* This is another instance we need to be concerned about securing our
stack space. If we write anything underneath %sp (r1), we might conflict
with the kernel who thinks he is free to use this area. So, update %sp
first before doing anything else. */
write_register (SP_REGNUM, sp);
/* if the last argument copied into the registers didn't fit there
completely, push the rest of it into stack. */
if (argbytes) {
write_memory (
sp+24+(ii*4), ((char*)VALUE_CONTENTS (arg))+argbytes, len - argbytes);
++argno;
ii += ((len - argbytes + 3) & -4) / 4;
}
/* push the rest of the arguments into stack. */
for (; argno < nargs; ++argno) {
arg = args[argno];
len = TYPE_LENGTH (VALUE_TYPE (arg));
/* float types should be passed in fpr's, as well as in the stack. */
if (TYPE_CODE (VALUE_TYPE (arg)) == TYPE_CODE_FLT && f_argno < 13) {
if (len > 8)
printf_unfiltered (
"Fatal Error: a floating point parameter #%d with a size > 8 is found!\n", argno);
memcpy (®isters[REGISTER_BYTE(FP0_REGNUM + 1 + f_argno)], VALUE_CONTENTS (arg),
len);
++f_argno;
}
write_memory (sp+24+(ii*4), (char *) VALUE_CONTENTS (arg), len);
ii += ((len + 3) & -4) / 4;
}
}
else
/* Secure stack areas first, before doing anything else. */
write_register (SP_REGNUM, sp);
saved_sp = dummy_frame_addr [dummy_frame_count - 1];
read_memory (saved_sp, tmp_buffer, 24);
write_memory (sp, tmp_buffer, 24);
/* set back chain properly */
store_address (tmp_buffer, 4, saved_sp);
write_memory (sp, tmp_buffer, 4);
target_store_registers (-1);
return sp;
}
/* a given return value in `regbuf' with a type `valtype', extract and copy its
value into `valbuf' */
void
extract_return_value (valtype, regbuf, valbuf)
struct type *valtype;
char regbuf[REGISTER_BYTES];
char *valbuf;
{
if (TYPE_CODE (valtype) == TYPE_CODE_FLT) {
double dd; float ff;
/* floats and doubles are returned in fpr1. fpr's have a size of 8 bytes.
We need to truncate the return value into float size (4 byte) if
necessary. */
if (TYPE_LENGTH (valtype) > 4) /* this is a double */
memcpy (valbuf, ®buf[REGISTER_BYTE (FP0_REGNUM + 1)],
TYPE_LENGTH (valtype));
else { /* float */
memcpy (&dd, ®buf[REGISTER_BYTE (FP0_REGNUM + 1)], 8);
ff = (float)dd;
memcpy (valbuf, &ff, sizeof(float));
}
}
else
/* return value is copied starting from r3. */
memcpy (valbuf, ®buf[REGISTER_BYTE (3)], TYPE_LENGTH (valtype));
}
/* keep structure return address in this variable.
FIXME: This is a horrid kludge which should not be allowed to continue
living. This only allows a single nested call to a structure-returning
function. Come on, guys! -- gnu@cygnus.com, Aug 92 */
CORE_ADDR rs6000_struct_return_address;
/* Indirect function calls use a piece of trampoline code to do context
switching, i.e. to set the new TOC table. Skip such code if we are on
its first instruction (as when we have single-stepped to here).
Also skip shared library trampoline code (which is different from
indirect function call trampolines).
Result is desired PC to step until, or NULL if we are not in
trampoline code. */
CORE_ADDR
skip_trampoline_code (pc)
CORE_ADDR pc;
{
register unsigned int ii, op;
CORE_ADDR solib_target_pc;
static unsigned trampoline_code[] = {
0x800b0000, /* l r0,0x0(r11) */
0x90410014, /* st r2,0x14(r1) */
0x7c0903a6, /* mtctr r0 */
0x804b0004, /* l r2,0x4(r11) */
0x816b0008, /* l r11,0x8(r11) */
0x4e800420, /* bctr */
0x4e800020, /* br */
0
};
/* If pc is in a shared library trampoline, return its target. */
solib_target_pc = find_solib_trampoline_target (pc);
if (solib_target_pc)
return solib_target_pc;
for (ii=0; trampoline_code[ii]; ++ii) {
op = read_memory_integer (pc + (ii*4), 4);
if (op != trampoline_code [ii])
return 0;
}
ii = read_register (11); /* r11 holds destination addr */
pc = read_memory_integer (ii, 4); /* (r11) value */
return pc;
}
/* Determines whether the function FI has a frame on the stack or not.
Called from the FRAMELESS_FUNCTION_INVOCATION macro in tm.h with a
second argument of 0, and from the FRAME_SAVED_PC macro with a
second argument of 1. */
int
frameless_function_invocation (fi, pcsaved)
struct frame_info *fi;
int pcsaved;
{
CORE_ADDR func_start;
struct aix_framedata fdata;
if (fi->next != NULL)
/* Don't even think about framelessness except on the innermost frame. */
/* FIXME: Can also be frameless if fi->next->signal_handler_caller (if
a signal happens while executing in a frameless function). */
return 0;
func_start = get_pc_function_start (fi->pc) + FUNCTION_START_OFFSET;
/* If we failed to find the start of the function, it is a mistake
to inspect the instructions. */
if (!func_start)
return 0;
function_frame_info (func_start, &fdata);
return pcsaved ? fdata.nosavedpc : fdata.frameless;
}
/* If saved registers of frame FI are not known yet, read and cache them.
&FDATAP contains aix_framedata; TDATAP can be NULL,
in which case the framedata are read. */
static void
frame_get_cache_fsr (fi, fdatap)
struct frame_info *fi;
struct aix_framedata *fdatap;
{
int ii;
CORE_ADDR frame_addr;
struct aix_framedata work_fdata;
if (fi->cache_fsr)
return;
if (fdatap == NULL) {
fdatap = &work_fdata;
function_frame_info (get_pc_function_start (fi->pc), fdatap);
}
fi->cache_fsr = (struct frame_saved_regs *)
obstack_alloc (&frame_cache_obstack, sizeof (struct frame_saved_regs));
memset (fi->cache_fsr, '\0', sizeof (struct frame_saved_regs));
if (fi->prev && fi->prev->frame)
frame_addr = fi->prev->frame;
else
frame_addr = read_memory_integer (fi->frame, 4);
/* if != -1, fdatap->saved_fpr is the smallest number of saved_fpr.
All fpr's from saved_fpr to fp31 are saved right underneath caller
stack pointer, starting from fp31 first. */
if (fdatap->saved_fpr >= 0) {
for (ii=31; ii >= fdatap->saved_fpr; --ii)
fi->cache_fsr->regs [FP0_REGNUM + ii] = frame_addr - ((32 - ii) * 8);
frame_addr -= (32 - fdatap->saved_fpr) * 8;
}
/* if != -1, fdatap->saved_gpr is the smallest number of saved_gpr.
All gpr's from saved_gpr to gpr31 are saved right under saved fprs,
starting from r31 first. */
if (fdatap->saved_gpr >= 0)
for (ii=31; ii >= fdatap->saved_gpr; --ii)
fi->cache_fsr->regs [ii] = frame_addr - ((32 - ii) * 4);
}
/* Return the address of a frame. This is the inital %sp value when the frame
was first allocated. For functions calling alloca(), it might be saved in
an alloca register. */
CORE_ADDR
frame_initial_stack_address (fi)
struct frame_info *fi;
{
CORE_ADDR tmpaddr;
struct aix_framedata fdata;
struct frame_info *callee_fi;
/* if the initial stack pointer (frame address) of this frame is known,
just return it. */
if (fi->initial_sp)
return fi->initial_sp;
/* find out if this function is using an alloca register.. */
function_frame_info (get_pc_function_start (fi->pc), &fdata);
/* if saved registers of this frame are not known yet, read and cache them. */
if (!fi->cache_fsr)
frame_get_cache_fsr (fi, &fdata);
/* If no alloca register used, then fi->frame is the value of the %sp for
this frame, and it is good enough. */
if (fdata.alloca_reg < 0) {
fi->initial_sp = fi->frame;
return fi->initial_sp;
}
/* This function has an alloca register. If this is the top-most frame
(with the lowest address), the value in alloca register is good. */
if (!fi->next)
return fi->initial_sp = read_register (fdata.alloca_reg);
/* Otherwise, this is a caller frame. Callee has usually already saved
registers, but there are exceptions (such as when the callee
has no parameters). Find the address in which caller's alloca
register is saved. */
for (callee_fi = fi->next; callee_fi; callee_fi = callee_fi->next) {
if (!callee_fi->cache_fsr)
frame_get_cache_fsr (callee_fi, NULL);
/* this is the address in which alloca register is saved. */
tmpaddr = callee_fi->cache_fsr->regs [fdata.alloca_reg];
if (tmpaddr) {
fi->initial_sp = read_memory_integer (tmpaddr, 4);
return fi->initial_sp;
}
/* Go look into deeper levels of the frame chain to see if any one of
the callees has saved alloca register. */
}
/* If alloca register was not saved, by the callee (or any of its callees)
then the value in the register is still good. */
return fi->initial_sp = read_register (fdata.alloca_reg);
}
CORE_ADDR
rs6000_frame_chain (thisframe)
struct frame_info *thisframe;
{
CORE_ADDR fp;
if (inside_entry_file ((thisframe)->pc))
return 0;
if (thisframe->signal_handler_caller)
fp = read_memory_integer (thisframe->frame + SIG_FRAME_FP_OFFSET, 4);
else
fp = read_memory_integer ((thisframe)->frame, 4);
return fp;
}
/* Keep an array of load segment information and their TOC table addresses.
This info will be useful when calling a shared library function by hand. */
struct loadinfo {
CORE_ADDR textorg, dataorg;
unsigned long toc_offset;
};
#define LOADINFOLEN 10
static struct loadinfo *loadinfo = NULL;
static int loadinfolen = 0;
static int loadinfotocindex = 0;
static int loadinfotextindex = 0;
void
xcoff_init_loadinfo ()
{
loadinfotocindex = 0;
loadinfotextindex = 0;
if (loadinfolen == 0) {
loadinfo = (struct loadinfo *)
xmalloc (sizeof (struct loadinfo) * LOADINFOLEN);
loadinfolen = LOADINFOLEN;
}
}
/* FIXME -- this is never called! */
void
free_loadinfo ()
{
if (loadinfo)
free (loadinfo);
loadinfo = NULL;
loadinfolen = 0;
loadinfotocindex = 0;
loadinfotextindex = 0;
}
/* this is called from xcoffread.c */
void
xcoff_add_toc_to_loadinfo (unsigned long tocoff)
{
while (loadinfotocindex >= loadinfolen) {
loadinfolen += LOADINFOLEN;
loadinfo = (struct loadinfo *)
xrealloc (loadinfo, sizeof(struct loadinfo) * loadinfolen);
}
loadinfo [loadinfotocindex++].toc_offset = tocoff;
}
void
add_text_to_loadinfo (textaddr, dataaddr)
CORE_ADDR textaddr;
CORE_ADDR dataaddr;
{
while (loadinfotextindex >= loadinfolen) {
loadinfolen += LOADINFOLEN;
loadinfo = (struct loadinfo *)
xrealloc (loadinfo, sizeof(struct loadinfo) * loadinfolen);
}
loadinfo [loadinfotextindex].textorg = textaddr;
loadinfo [loadinfotextindex].dataorg = dataaddr;
++loadinfotextindex;
}
/* FIXME: This assumes that the "textorg" and "dataorg" elements
of a member of this array are correlated with the "toc_offset"
element of the same member. But they are sequentially assigned in wildly
different places, and probably there is no correlation. FIXME! */
static CORE_ADDR
find_toc_address (pc)
CORE_ADDR pc;
{
int ii, toc_entry, tocbase = 0;
for (ii=0; ii < loadinfotextindex; ++ii)
if (pc > loadinfo[ii].textorg && loadinfo[ii].textorg > tocbase) {
toc_entry = ii;
tocbase = loadinfo[ii].textorg;
}
return loadinfo[toc_entry].dataorg + loadinfo[toc_entry].toc_offset;
}
void
_initialize_rs6000_tdep ()
{
/* FIXME, this should not be decided via ifdef. */
#ifdef GDB_TARGET_POWERPC
tm_print_insn = print_insn_big_powerpc;
#else
tm_print_insn = print_insn_rs6000;
#endif
}
|