aboutsummaryrefslogtreecommitdiff
path: root/gdb/convex-xdep.c
blob: 60b090c177cdd398ab245eeb7d7d1b055a7847ee (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
/* Convex stuff for GDB.
   Copyright (C) 1990-1991 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 <stdio.h>
#include "defs.h"
#include "command.h"
#include "symtab.h"
#include "value.h"
#include "frame.h"
#include "inferior.h"
#include "wait.h"

#include <signal.h>
#include <fcntl.h>
#include "gdbcore.h"

#include <sys/param.h>
#include <sys/dir.h>
#include <sys/user.h>
#include <sys/ioctl.h>
#include <sys/pcntl.h>
#include <sys/thread.h>
#include <sys/proc.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <sys/mman.h>

#include <convex/vmparam.h>
#include <convex/filehdr.h>
#include <convex/opthdr.h>
#include <convex/scnhdr.h>
#include <convex/core.h>

/* Per-thread data, read from the inferior at each stop and written
   back at each resume.  */

/* Number of active threads.
   Tables are valid for thread numbers less than this.  */

static int n_threads;

#define MAXTHREADS 8
		
/* Thread state.  The remaining data is valid only if this is PI_TALIVE.  */

static int thread_state[MAXTHREADS];

/* Stop pc, signal, signal subcode */

static int thread_pc[MAXTHREADS];
static int thread_signal[MAXTHREADS];
static int thread_sigcode[MAXTHREADS];	

/* Thread registers.
   If thread is selected, the regs are in registers[] instead.  */

static char thread_regs[MAXTHREADS][REGISTER_BYTES];

/* 1 if the top frame on the thread's stack was a context frame,
   meaning that the kernel is up to something and we should not
   touch the thread at all except to resume it.  */

static char thread_is_in_kernel[MAXTHREADS];

/* The currently selected thread's number.  */

static int inferior_thread;

/* Inferior process's file handle and a process control block
   to feed args to ioctl with.  */

static int inferior_fd;
static struct pcntl ps;

/* SOFF file headers for exec or core file.  */

static FILEHDR filehdr;
static OPTHDR opthdr;
static SCNHDR scnhdr;

/* Address maps constructed from section headers of exec and core files.
   Defines process address -> file address translation.  */

struct pmap 
{
    long mem_addr;		/* process start address */
    long mem_end;		/* process end+1 address */
    long file_addr;		/* file start address */
    long thread;		/* -1 shared; 0,1,... thread-local */
    long type;			/* S_TEXT S_DATA S_BSS S_TBSS etc */
    long which;			/* used to sort map for info files */
};

static int n_exec, n_core;
static struct pmap exec_map[100];
static struct pmap core_map[100];

/* Offsets in the core file of core_context and core_tcontext blocks.  */

static int context_offset;
static int tcontext_offset[MAXTHREADS];

/* Core file control blocks.  */

static struct core_context_v70 c;
static struct core_tcontext_v70 tc;
static struct user u;
static thread_t th;
static proc_t pr;

/* The registers of the currently selected thread.  */

extern char registers[REGISTER_BYTES];

/* Vector and communication registers from core dump or from inferior.
   These are read on demand, ie, not normally valid.  */

static struct vecst vector_registers;
static struct creg_ctx comm_registers;

/* Flag, set on a vanilla CONT command and cleared when the inferior
   is continued.  */

static int all_continue;

/* Flag, set when the inferior is continued by a vanilla CONT command,
   cleared if it is continued for any other purpose.  */

static int thread_switch_ok;

/* Stack of signals recieved from threads but not yet delivered to gdb.  */

struct threadpid 
{
    int pid;
    int thread;
    int signo;
    int subsig;
    int pc;
};

static struct threadpid signal_stack_bot[100];
static struct threadpid *signal_stack = signal_stack_bot;

/* How to detect empty stack -- bottom frame is all zero.  */

#define signal_stack_is_empty() (signal_stack->pid == 0)

/* Mode controlled by SET PIPE command, controls the psw SEQ bit
   which forces each instruction to complete before the next one starts.  */

static int sequential = 0;

/* Mode controlled by the SET PARALLEL command.  Values are:
   0  concurrency limit 1 thread, dynamic scheduling
   1  no concurrency limit, dynamic scheduling
   2  no concurrency limit, fixed scheduling  */

static int parallel = 1;

/* Mode controlled by SET BASE command, output radix for unformatted
   integer typeout, as in argument lists, aggregates, and so on.
   Zero means guess whether it's an address (hex) or not (decimal).  */

static int output_radix = 0;

/* Signal subcode at last thread stop.  */

static int stop_sigcode;

/* Hack, see wait() below.  */

static int exec_trap_timer;

#include "gdbcmd.h"

/* Nonzero if we are debugging an attached outside process
   rather than an inferior.  */

extern int attach_flag;



static struct type *vector_type ();
static long *read_vector_register ();
static long *read_vector_register_1 ();
static void write_vector_register ();
static REGISTER_TYPE read_comm_register ();
static void write_comm_register ();
static void convex_cont_command ();
static void thread_continue ();
static void select_thread ();
static void scan_stack ();
static void set_fixed_scheduling ();
static char *subsig_name ();
static void psw_info ();
static sig_noop ();
static ptr_cmp ();

extern char *sys_siglist[];

/* Execute ptrace.  Convex V7 replaced ptrace with pattach.
   Allow ptrace (0) as a no-op.  */

int
call_ptrace (request, pid, procaddr, buf)
     int request, pid, procaddr, buf;
{
  if (request == 0)
    return;
  error ("no ptrace");
}

/* Replacement for system execle routine.
   Convert it to an equivalent exect, which pattach insists on.  */

execle (name, argv)
     char *name, *argv;
{
  char ***envp = (char ***) &argv;
  while (*envp++) ;

  signal (SIGTRAP, sig_noop);
  exect (name, &argv, *envp);
}

/* Stupid handler for stupid trace trap that otherwise causes
   startup to stupidly hang.  */

static sig_noop () 
{}

/* Read registers from inferior into registers[] array.
   For convex, they are already there, read in when the inferior stops.  */

void
fetch_inferior_registers (regno)
     int regno;
{
}

/* Store our register values back into the inferior.
   For Convex, do this only once, right before resuming inferior.  */

void
store_inferior_registers (regno)
     int regno;
{
}

/* Copy LEN bytes from inferior's memory starting at MEMADDR
   to debugger memory starting at MYADDR. 
   On failure (cannot read from inferior, usually because address is out
   of bounds) returns the value of errno. */

int
read_inferior_memory (memaddr, myaddr, len)
     CORE_ADDR memaddr;
     char *myaddr;
     int len;
{
  errno = 0;
  while (len > 0)
    {
      /* little-known undocumented max request size */
      int i = (len < 12288) ? len : 12288;

      lseek (inferior_fd, memaddr, 0);
      read (inferior_fd, myaddr, i);

      memaddr += i;
      myaddr += i;
      len -= i;
    }
  if (errno) 
    bzero (myaddr, len);
  return errno;
}

/* Copy LEN bytes of data from debugger memory at MYADDR
   to inferior's memory at MEMADDR.
   Returns errno on failure (cannot write the inferior) */

int
write_inferior_memory (memaddr, myaddr, len)
     CORE_ADDR memaddr;
     char *myaddr;
     int len;
{
  errno = 0;
  lseek (inferior_fd, memaddr, 0);
  write (inferior_fd, myaddr, len);
  return errno;
}

/* Here from create_inferior when the inferior process has been created
   and started up.  We must do a pattach to grab it for debugging.

   Also, intercept the CONT command by altering its dispatch address.  */

create_inferior_hook (pid)
    int pid;
{
  static char cont[] = "cont";
  static char cont1[] = "c";
  char *linep = cont;
  char *linep1 = cont1;
  char **line = &linep;
  char **line1 = &linep1;
  struct cmd_list_element *c;

  c = lookup_cmd (line, cmdlist, "", 0);
  c->function = convex_cont_command;
  c = lookup_cmd (line1, cmdlist, "", 0);
  c->function = convex_cont_command;

  inferior_fd = pattach (pid, O_EXCL);
  if (inferior_fd < 0)
    perror_with_name ("pattach");
  inferior_thread = 0;
  set_fixed_scheduling (pid, parallel == 2);
}

/* Attach process PID for debugging.  */

attach (pid)
    int pid;
{
  int fd = pattach (pid, O_EXCL);
  if (fd < 0)
    perror_with_name ("pattach");
  attach_flag = 1;
  /* wait for strange kernel reverberations to go away */
  sleep (1);

  setpgrp (pid, pid);

  inferior_fd = fd;
  inferior_thread = 0;
  return pid;
}

/* Stop debugging the process whose number is PID
   and continue it with signal number SIGNAL.
   SIGNAL = 0 means just continue it.  */

void
detach (signal)
     int signal;
{
  signal_stack = signal_stack_bot;
  thread_continue (-1, 0, signal);
  ioctl (inferior_fd, PIXDETACH, &ps);
  close (inferior_fd);
  inferior_fd = 0;
  attach_flag = 0;
}

/* Kill off the inferior process.  */

kill_inferior ()
{
  if (inferior_pid == 0)
    return;
  ioctl (inferior_fd, PIXTERMINATE, 0);
  wait (0);
  target_mourn_inferior ();
}

/* This is used when GDB is exiting.  It gives less chance of error.*/

kill_inferior_fast ()
{
  if (inferior_pid == 0)
    return;
  ioctl (inferior_fd, PIXTERMINATE, 0);
  wait (0);
}

/* Read vector register REG, and return a pointer to the value.  */

static long *
read_vector_register (reg)
    int reg;
{
  if (have_inferior_p ())
    {
      errno = 0;
      ps.pi_buffer = (char *) &vector_registers;
      ps.pi_nbytes = sizeof vector_registers;
      ps.pi_offset = 0;
      ps.pi_thread = inferior_thread;
      ioctl (inferior_fd, PIXRDVREGS, &ps);
      if (errno)
	bzero (&vector_registers, sizeof vector_registers);
    }
  else if (corechan >= 0)
    {
      lseek (corechan, tcontext_offset[inferior_thread], 0);
      if (myread (corechan, &tc, sizeof tc) < 0)
	perror_with_name (corefile);
      lseek (corechan, tc.core_thread_p, 0);
      if (myread (corechan, &th, sizeof th) < 0)
	perror_with_name (corefile);
      lseek (corechan, tc.core_vregs_p, 0);
      if (myread (corechan, &vector_registers, 16*128) < 0)
	perror_with_name (corefile);
      vector_registers.vm[0] = th.t_vect_ctx.vc_vm[0];
      vector_registers.vm[1] = th.t_vect_ctx.vc_vm[1];
      vector_registers.vls = th.t_vect_ctx.vc_vls;
    }

  return read_vector_register_1 (reg);
}

/* Return a pointer to vector register REG, which must already have been
   fetched from the inferior or core file.  */

static long *
read_vector_register_1 (reg) 
    int reg;
{
  switch (reg)
    {
    case VM_REGNUM:
      return (long *) vector_registers.vm;
    case VS_REGNUM:
      return (long *) &vector_registers.vls;
    case VL_REGNUM:
      return 1 + (long *) &vector_registers.vls;
    default:
      return (long *) &vector_registers.vr[reg];
    }
}

/* Write vector register REG, element ELEMENT, new value VAL.
   NB: must use read-modify-write on the entire vector state,
   since pattach does not do offsetted writes correctly.  */

static void
write_vector_register (reg, element, val)
    int reg, element;
    REGISTER_TYPE val;
{
  if (have_inferior_p ())
    {
      errno = 0;
      ps.pi_thread = inferior_thread;
      ps.pi_offset = 0;
      ps.pi_buffer = (char *) &vector_registers;
      ps.pi_nbytes = sizeof vector_registers;

      ioctl (inferior_fd, PIXRDVREGS, &ps);

      switch (reg)
	{
	case VL_REGNUM:
	  vector_registers.vls =
	    (vector_registers.vls & 0xffffffff00000000LL)
	      + (unsigned long) val;
	  break;

	case VS_REGNUM:
	  vector_registers.vls =
	    (val << 32) + (unsigned long) vector_registers.vls;
	  break;
	    
	default:
	  vector_registers.vr[reg].el[element] = val;
	  break;
	}

      ioctl (inferior_fd, PIXWRVREGS, &ps);

      if (errno)
	perror_with_name ("writing vector register");
    }
}

/* Return the contents of communication register NUM.  */ 

static REGISTER_TYPE 
read_comm_register (num)
     int num;
{
  if (have_inferior_p ())
    {
      ps.pi_buffer = (char *) &comm_registers;
      ps.pi_nbytes = sizeof comm_registers;
      ps.pi_offset = 0;
      ps.pi_thread = inferior_thread;
      ioctl (inferior_fd, PIXRDCREGS, &ps);
    }
  return comm_registers.crreg.r4[num];
}

/* Store a new value VAL into communication register NUM.  
   NB: Must use read-modify-write on the whole comm register set
   since pattach does not do offsetted writes correctly.  */

static void
write_comm_register (num, val)
     int num;
     REGISTER_TYPE val;
{
  if (have_inferior_p ())
    {
      ps.pi_buffer = (char *) &comm_registers;
      ps.pi_nbytes = sizeof comm_registers;
      ps.pi_offset = 0;
      ps.pi_thread = inferior_thread;
      ioctl (inferior_fd, PIXRDCREGS, &ps);
      comm_registers.crreg.r4[num] = val;
      ioctl (inferior_fd, PIXWRCREGS, &ps);
    }
}

/* Resume execution of the inferior process.
   If STEP is nonzero, single-step it.
   If SIGNAL is nonzero, give it that signal.  */

void
resume (step, signal)
     int step;
     int signal;
{
  errno = 0;
  if (step || signal)
    thread_continue (inferior_thread, step, signal);
  else
    thread_continue (-1, 0, 0);
}

/* Maybe resume some threads.
   THREAD is which thread to resume, or -1 to resume them all.
   STEP and SIGNAL are as in resume.

   Global variable ALL_CONTINUE is set when we are here to do a
   `cont' command; otherwise we may be doing `finish' or a call or
   something else that will not tolerate an automatic thread switch.

   If there are stopped threads waiting to deliver signals, and
   ALL_CONTINUE, do not actually resume anything.  gdb will do a wait
   and see one of the stopped threads in the queue.  */

static void
thread_continue (thread, step, signal)
     int thread, step, signal;
{
  int n;

  /* If we are to continue all threads, but not for the CONTINUE command,
     pay no attention and continue only the selected thread.  */

  if (thread < 0 && ! all_continue)
    thread = inferior_thread;

  /* If we are not stepping, we have now executed the continue part
     of a CONTINUE command.  */

  if (! step)
    all_continue = 0;

  /* Allow wait() to switch threads if this is an all-out continue.  */

  thread_switch_ok = thread < 0;

  /* If there are threads queued up, don't resume.  */

  if (thread_switch_ok && ! signal_stack_is_empty ())
    return;

  /* OK, do it.  */

  for (n = 0; n < n_threads; n++)
    if (thread_state[n] == PI_TALIVE)
      {
	select_thread (n);

	if ((thread < 0 || n == thread) && ! thread_is_in_kernel[n])
	  {
	    /* Blam the trace bits in the stack's saved psws to match 
	       the desired step mode.  This is required so that
	       single-stepping a return doesn't restore a psw with a
	       clear trace bit and fly away, and conversely,
	       proceeding through a return in a routine that was
	       stepped into doesn't cause a phantom break by restoring
	       a psw with the trace bit set. */
	    scan_stack (PSW_T_BIT, step);
	    scan_stack (PSW_S_BIT, sequential);
	  }

	ps.pi_buffer = registers;
	ps.pi_nbytes = REGISTER_BYTES;
	ps.pi_offset = 0;
	ps.pi_thread = n;
	if (! thread_is_in_kernel[n])
	  if (ioctl (inferior_fd, PIXWRREGS, &ps))
	    perror_with_name ("PIXWRREGS");

	if (thread < 0 || n == thread)
	  {
	    ps.pi_pc = 1;
	    ps.pi_signo = signal;
	    if (ioctl (inferior_fd, step ? PIXSTEP : PIXCONTINUE, &ps) < 0)
	      perror_with_name ("PIXCONTINUE");
	  }
      }

  if (ioctl (inferior_fd, PIXRUN, &ps) < 0)
    perror_with_name ("PIXRUN");
}

/* Replacement for system wait routine.  

   The system wait returns with one or more threads stopped by
   signals.  Put stopped threads on a stack and return them one by
   one, so that it appears that wait returns one thread at a time.

   Global variable THREAD_SWITCH_OK is set when gdb can tolerate wait
   returning a new thread.  If it is false, then only one thread is
   running; we will do a real wait, the thread will do something, and
   we will return that.  */

pid_t
wait (w)
    union wait *w;
{
  int pid;

  if (!w)
    return wait3 (0, 0, 0);

  /* Do a real wait if we were told to, or if there are no queued threads.  */

  if (! thread_switch_ok || signal_stack_is_empty ())
    {
      int thread;

      pid = wait3 (w, 0, 0);

      if (!WIFSTOPPED (*w) || pid != inferior_pid)
	return pid;

      /* The inferior has done something and stopped.  Read in all the
	 threads' registers, and queue up any signals that happened.  */

      if (ioctl (inferior_fd, PIXGETTHCOUNT, &ps) < 0)
	perror_with_name ("PIXGETTHCOUNT");
      
      n_threads = ps.pi_othdcnt;
      for (thread = 0; thread < n_threads; thread++)
	{
	  ps.pi_thread = thread;
	  if (ioctl (inferior_fd, PIXGETSUBCODE, &ps) < 0)
	    perror_with_name ("PIXGETSUBCODE");
	  thread_state[thread] = ps.pi_otstate;

	  if (ps.pi_otstate == PI_TALIVE)
	    {
	      select_thread (thread);
	      ps.pi_buffer = registers;
	      ps.pi_nbytes = REGISTER_BYTES;
	      ps.pi_offset = 0;
	      ps.pi_thread = thread;
	      if (ioctl (inferior_fd, PIXRDREGS, &ps) < 0)
		perror_with_name ("PIXRDREGS");

	      registers_fetched ();

	      thread_pc[thread] = read_pc ();
	      thread_signal[thread] = ps.pi_osigno;
	      thread_sigcode[thread] = ps.pi_osigcode;

	      /* If the thread's stack has a context frame
		 on top, something fucked is going on.  I do not
		 know what, but do I know this: the only thing you
		 can do with such a thread is continue it.  */

	      thread_is_in_kernel[thread] = 
		((read_register (PS_REGNUM) >> 25) & 3) == 0;

	      /* Signals push an extended frame and then fault
		 with a ridiculous pc.  Pop the frame.  */

	      if (thread_pc[thread] > STACK_END_ADDR)
		{
		  POP_FRAME;
		  if (is_break_pc (thread_pc[thread]))
		    thread_pc[thread] = read_pc () - 2;
		  else
		    thread_pc[thread] = read_pc ();
		  write_register (PC_REGNUM, thread_pc[thread]);
		}
	      
	      if (ps.pi_osigno || ps.pi_osigcode)
		{
		  signal_stack++;
		  signal_stack->pid = pid;
		  signal_stack->thread = thread;
		  signal_stack->signo = thread_signal[thread];
		  signal_stack->subsig = thread_sigcode[thread];
		  signal_stack->pc = thread_pc[thread];
		}

	      /* The following hackery is caused by a unix 7.1 feature:
		 the inferior's fixed scheduling mode is cleared when
		 it execs the shell (since the shell is not a parallel
		 program).  So, note the 5.4 trap we get when
		 the shell does its exec, then catch the 5.0 trap 
		 that occurs when the debuggee starts, and set fixed
		 scheduling mode properly.  */

	      if (ps.pi_osigno == 5 && ps.pi_osigcode == 4)
		exec_trap_timer = 1;
	      else
		exec_trap_timer--;
	      
	      if (ps.pi_osigno == 5 && exec_trap_timer == 0)
		set_fixed_scheduling (pid, parallel == 2);
	    }
	}

      if (signal_stack_is_empty ())
	error ("no active threads?!");
    }

  /* Select the thread that stopped, and return *w saying why.  */

  select_thread (signal_stack->thread);

  stop_signal = signal_stack->signo;
  stop_sigcode = signal_stack->subsig;

  WSETSTOP (*w, signal_stack->signo);
  w->w_thread = signal_stack->thread;
  return (signal_stack--)->pid;
}

/* Select thread THREAD -- its registers, stack, per-thread memory.
   This is the only routine that may assign to inferior_thread
   or thread_regs[].  */

static void
select_thread (thread)
     int thread;
{
  if (thread == inferior_thread)
    return;

  bcopy (registers, thread_regs[inferior_thread], REGISTER_BYTES);
  ps.pi_thread = inferior_thread = thread;
  if (have_inferior_p ())
    ioctl (inferior_fd, PISETRWTID, &ps);
  bcopy (thread_regs[thread], registers, REGISTER_BYTES);
}
  
/* Routine to set or clear a psw bit in the psw and also all psws
   saved on the stack.  Quits when we get to a frame in which the
   saved psw is correct. */

static void
scan_stack (bit, val)
    long bit, val;
{
  long ps = read_register (PS_REGNUM);
  long fp;
  if (val ? !(ps & bit) : (ps & bit))
    {    
      ps ^= bit;
      write_register (PS_REGNUM, ps);

      fp = read_register (FP_REGNUM);
      while (fp & 0x80000000)
	{
	  ps = read_memory_integer (fp + 4, 4);
	  if (val ? (ps & bit) : !(ps & bit))
	    break;
	  ps ^= bit;
	  write_memory (fp + 4, &ps, 4);
	  fp = read_memory_integer (fp + 8, 4);
	}
    }
}

/* Set fixed scheduling (alliant mode) of process PID to ARG (0 or 1).  */

static void
set_fixed_scheduling (pid, arg)
      int arg;
{
  struct pattributes pattr;
  getpattr (pid, &pattr);
  pattr.pattr_pfixed = arg;
  setpattr (pid, &pattr);
}

void
core_file_command (filename, from_tty)
     char *filename;
     int from_tty;
{
  int n;

  /* Discard all vestiges of any previous core file
     and mark data and stack spaces as empty.  */

  if (corefile)
    free (corefile);
  corefile = 0;

  if (corechan >= 0)
    close (corechan);
  corechan = -1;

  data_start = 0;
  data_end = 0;
  stack_start = STACK_END_ADDR;
  stack_end = STACK_END_ADDR;
  n_core = 0;

  /* Now, if a new core file was specified, open it and digest it.  */

  if (filename)
    {
      filename = tilde_expand (filename);
      make_cleanup (free, filename);
      
      if (have_inferior_p ())
	error ("To look at a core file, you must kill the inferior with \"kill\".");
      corechan = open (filename, O_RDONLY, 0);
      if (corechan < 0)
	perror_with_name (filename);

      if (myread (corechan, &filehdr, sizeof filehdr) < 0)
	perror_with_name (filename);

      if (!IS_CORE_SOFF_MAGIC (filehdr.h_magic))
	error ("%s: not a core file.\n", filename);

      if (myread (corechan, &opthdr, filehdr.h_opthdr) < 0)
	perror_with_name (filename);

      /* Read through the section headers.
	 For text, data, etc, record an entry in the core file map.
	 For context and tcontext, record the file address of
	 the context blocks.  */

      lseek (corechan, (long) filehdr.h_scnptr, 0);

      n_threads = 0;
      for (n = 0; n < filehdr.h_nscns; n++)
	{
	  if (myread (corechan, &scnhdr, sizeof scnhdr) < 0)
	    perror_with_name (filename);
	  if ((scnhdr.s_flags & S_TYPMASK) >= S_TEXT
	      && (scnhdr.s_flags & S_TYPMASK) <= S_COMON)
	    {
	      core_map[n_core].mem_addr = scnhdr.s_vaddr;
	      core_map[n_core].mem_end = scnhdr.s_vaddr + scnhdr.s_size;
	      core_map[n_core].file_addr = scnhdr.s_scnptr;
	      core_map[n_core].type = scnhdr.s_flags & S_TYPMASK;
	      if (core_map[n_core].type != S_TBSS
		  && core_map[n_core].type != S_TDATA
		  && core_map[n_core].type != S_TTEXT)
		core_map[n_core].thread = -1;
	      else if (n_core == 0
		       || core_map[n_core-1].mem_addr != scnhdr.s_vaddr)
		core_map[n_core].thread = 0;
	      else 
		core_map[n_core].thread = core_map[n_core-1].thread + 1;
	      n_core++;
	    }
	  else if ((scnhdr.s_flags & S_TYPMASK) == S_CONTEXT)
	    context_offset = scnhdr.s_scnptr;
	  else if ((scnhdr.s_flags & S_TYPMASK) == S_TCONTEXT) 
	    tcontext_offset[n_threads++] = scnhdr.s_scnptr;
	}

      /* Read the context block, struct user, struct proc,
	 and the comm regs.  */

      lseek (corechan, context_offset, 0);
      if (myread (corechan, &c, sizeof c) < 0)
	perror_with_name (filename);
      lseek (corechan, c.core_user_p, 0);
      if (myread (corechan, &u, sizeof u) < 0)
	perror_with_name (filename);
      lseek (corechan, c.core_proc_p, 0);
      if (myread (corechan, &pr, sizeof pr) < 0)
	perror_with_name (filename);
      comm_registers = pr.p_creg;

      /* Core file apparently is really there.  Make it really exist
	 for xfer_core_file so we can do read_memory on it. */

      if (filename[0] == '/')
	corefile = savestring (filename, strlen (filename));
      else
	corefile = concat (current_directory, "/", filename, NULL);

      printf_filtered ("Program %s ", u.u_comm);

      /* Read the thread registers and fill in the thread_xxx[] data.  */

      for (n = 0; n < n_threads; n++)
	{
	  select_thread (n);

	  lseek (corechan, tcontext_offset[n], 0);
	  if (myread (corechan, &tc, sizeof tc) < 0)
	    perror_with_name (corefile);
	  lseek (corechan, tc.core_thread_p, 0);
	  if (myread (corechan, &th, sizeof th) < 0)
	    perror_with_name (corefile);

	  lseek (corechan, tc.core_syscall_context_p, 0);
	  if (myread (corechan, registers, REGISTER_BYTES) < 0)
	    perror_with_name (corefile);

	  thread_signal[n] = th.t_cursig;
	  thread_sigcode[n] = th.t_code;
	  thread_state[n] = th.t_state;
	  thread_pc[n] = read_pc ();

	  if (thread_pc[n] > STACK_END_ADDR)
	    {
	      POP_FRAME;
	      if (is_break_pc (thread_pc[n]))
		thread_pc[n] = read_pc () - 2;
	      else
		thread_pc[n] = read_pc ();
	      write_register (PC_REGNUM, thread_pc[n]);
	    }

	  printf_filtered ("thread %d received signal %d, %s\n",
			   n, thread_signal[n],
			   thread_signal[n] < NSIG
			   ? sys_siglist[thread_signal[n]]
			   : "(undocumented)");
	}

      /* Select an interesting thread -- also-rans died with SIGKILL,
	 so find one that didn't.  */

      for (n = 0; n < n_threads; n++)
	if (thread_signal[n] != 0 && thread_signal[n] != SIGKILL)
	  {
	    select_thread (n);
	    stop_signal = thread_signal[n];
	    stop_sigcode = thread_sigcode[n];
	    break;
	  }

      core_aouthdr.a_magic = 0;

      flush_cached_frames ();
      set_current_frame (create_new_frame (read_register (FP_REGNUM),
					     read_pc ()));
      select_frame (get_current_frame (), 0);
      validate_files ();

      print_stack_frame (selected_frame, selected_frame_level, -1);
    }
  else if (from_tty)
    printf_filtered ("No core file now.\n");
}