aboutsummaryrefslogtreecommitdiff
path: root/gdb/rs6000-nat.c
blob: 1c80a7a9807580da88e7b7469b24f675027f3a03 (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
/* IBM RS/6000 native-dependent code for GDB, the GNU debugger.
   Copyright 1986, 1987, 1989, 1991, 1992, 1994 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 "inferior.h"
#include "target.h"
#include "gdbcore.h"
#include "xcoffsolib.h"
#include "symfile.h"
#include "objfiles.h"
#include "libbfd.h"		/* BFD internals (sigh!)  FIXME */
#include "bfd.h"

#include <sys/ptrace.h>
#include <sys/reg.h>

#include <sys/param.h>
#include <sys/dir.h>
#include <sys/user.h>
#include <signal.h>
#include <sys/ioctl.h>
#include <fcntl.h>

#include <a.out.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <sys/core.h>
#include <sys/ldr.h>

extern int errno;

extern struct vmap * map_vmap PARAMS ((bfd *bf, bfd *arch));

extern struct target_ops exec_ops;

static void
exec_one_dummy_insn PARAMS ((void));

extern void
add_text_to_loadinfo PARAMS ((CORE_ADDR textaddr, CORE_ADDR dataaddr));

extern void
fixup_breakpoints PARAMS ((CORE_ADDR low, CORE_ADDR high, CORE_ADDR delta));

/* Conversion from gdb-to-system special purpose register numbers.. */

static int special_regs[] = {
  IAR,				/* PC_REGNUM	*/
  MSR,				/* PS_REGNUM	*/
  CR,				/* CR_REGNUM	*/
  LR,				/* LR_REGNUM	*/
  CTR,				/* CTR_REGNUM	*/
  XER,				/* XER_REGNUM   */
  MQ				/* MQ_REGNUM	*/
};

void
fetch_inferior_registers (regno)
  int regno;
{
  int ii;
  extern char registers[];

  if (regno < 0) {			/* for all registers */

    /* read 32 general purpose registers. */

    for (ii=0; ii < 32; ++ii)
      *(int*)&registers[REGISTER_BYTE (ii)] = 
	ptrace (PT_READ_GPR, inferior_pid, (PTRACE_ARG3_TYPE) ii, 0, 0);

    /* read general purpose floating point registers. */

    for (ii=0; ii < 32; ++ii)
      ptrace (PT_READ_FPR, inferior_pid, 
	      (PTRACE_ARG3_TYPE) &registers [REGISTER_BYTE (FP0_REGNUM+ii)],
	      FPR0+ii, 0);

    /* read special registers. */
    for (ii=0; ii <= LAST_SP_REGNUM-FIRST_SP_REGNUM; ++ii)
      *(int*)&registers[REGISTER_BYTE (FIRST_SP_REGNUM+ii)] = 
	ptrace (PT_READ_GPR, inferior_pid, (PTRACE_ARG3_TYPE) special_regs[ii],
		0, 0);

    registers_fetched ();
    return;
  }

  /* else an individual register is addressed. */

  else if (regno < FP0_REGNUM) {		/* a GPR */
    *(int*)&registers[REGISTER_BYTE (regno)] =
	ptrace (PT_READ_GPR, inferior_pid, (PTRACE_ARG3_TYPE) regno, 0, 0);
  }
  else if (regno <= FPLAST_REGNUM) {		/* a FPR */
    ptrace (PT_READ_FPR, inferior_pid,
	    (PTRACE_ARG3_TYPE) &registers [REGISTER_BYTE (regno)],
	    (regno-FP0_REGNUM+FPR0), 0);
  }
  else if (regno <= LAST_SP_REGNUM) {		/* a special register */
    *(int*)&registers[REGISTER_BYTE (regno)] =
	ptrace (PT_READ_GPR, inferior_pid,
		(PTRACE_ARG3_TYPE) special_regs[regno-FIRST_SP_REGNUM], 0, 0);
  }
  else
    fprintf_unfiltered (gdb_stderr, "gdb error: register no %d not implemented.\n", regno);

  register_valid [regno] = 1;
}

/* Store our register values back into the inferior.
   If REGNO is -1, do this for all registers.
   Otherwise, REGNO specifies which register (so we can save time).  */

void
store_inferior_registers (regno)
     int regno;
{
  extern char registers[];

  errno = 0;

  if (regno == -1)
    {			/* for all registers..	*/
      int ii;

       /* execute one dummy instruction (which is a breakpoint) in inferior
          process. So give kernel a chance to do internal house keeping.
	  Otherwise the following ptrace(2) calls will mess up user stack
	  since kernel will get confused about the bottom of the stack (%sp) */

       exec_one_dummy_insn ();

      /* write general purpose registers first! */
      for ( ii=GPR0; ii<=GPR31; ++ii)
	{
	  ptrace (PT_WRITE_GPR, inferior_pid, (PTRACE_ARG3_TYPE) ii,
		  *(int*)&registers[REGISTER_BYTE (ii)], 0);
	  if (errno)
	    { 
	      perror ("ptrace write_gpr");
	      errno = 0;
	    }
	}

      /* write floating point registers now. */
      for ( ii=0; ii < 32; ++ii)
	{
	  ptrace (PT_WRITE_FPR, inferior_pid, 
		  (PTRACE_ARG3_TYPE) &registers[REGISTER_BYTE (FP0_REGNUM+ii)],
		  FPR0+ii, 0);
	  if (errno)
	    {
	      perror ("ptrace write_fpr");
	      errno = 0;
	    }
	}

      /* write special registers. */
      for (ii=0; ii <= LAST_SP_REGNUM-FIRST_SP_REGNUM; ++ii)
	{
	  ptrace (PT_WRITE_GPR, inferior_pid,
		  (PTRACE_ARG3_TYPE) special_regs[ii],
		  *(int*)&registers[REGISTER_BYTE (FIRST_SP_REGNUM+ii)], 0);
	  if (errno)
	    {
	      perror ("ptrace write_gpr");
	      errno = 0;
	    }
	}
    }

  /* else, a specific register number is given... */

  else if (regno < FP0_REGNUM)			/* a GPR */
    {
      ptrace (PT_WRITE_GPR, inferior_pid, (PTRACE_ARG3_TYPE) regno,
	      *(int*)&registers[REGISTER_BYTE (regno)], 0);
    }

  else if (regno <= FPLAST_REGNUM)		/* a FPR */
    {
      ptrace (PT_WRITE_FPR, inferior_pid, 
	      (PTRACE_ARG3_TYPE) &registers[REGISTER_BYTE (regno)],
	      regno - FP0_REGNUM + FPR0, 0);
    }

  else if (regno <= LAST_SP_REGNUM)		/* a special register */
    {
      ptrace (PT_WRITE_GPR, inferior_pid,
	      (PTRACE_ARG3_TYPE) special_regs [regno-FIRST_SP_REGNUM],
	      *(int*)&registers[REGISTER_BYTE (regno)], 0);
    }

  else
    fprintf_unfiltered (gdb_stderr, "Gdb error: register no %d not implemented.\n", regno);

  if (errno)
    {
      perror ("ptrace write");
      errno = 0;
    }
}

/* Execute one dummy breakpoint instruction.  This way we give the kernel
   a chance to do some housekeeping and update inferior's internal data,
   including u_area. */

static void
exec_one_dummy_insn ()
{
#define	DUMMY_INSN_ADDR	(TEXT_SEGMENT_BASE)+0x200

  char shadow_contents[BREAKPOINT_MAX];	/* Stash old bkpt addr contents */
  unsigned int status, pid;

  /* We plant one dummy breakpoint into DUMMY_INSN_ADDR address. We assume that
     this address will never be executed again by the real code. */

  target_insert_breakpoint (DUMMY_INSN_ADDR, shadow_contents);

  errno = 0;
  ptrace (PT_CONTINUE, inferior_pid, (PTRACE_ARG3_TYPE) DUMMY_INSN_ADDR, 0, 0);
  if (errno)
    perror ("pt_continue");

  do {
    pid = wait (&status);
  } while (pid != inferior_pid);
    
  target_remove_breakpoint (DUMMY_INSN_ADDR, shadow_contents);
}

void
fetch_core_registers (core_reg_sect, core_reg_size, which, reg_addr)
     char *core_reg_sect;
     unsigned core_reg_size;
     int which;
     unsigned int reg_addr;	/* Unused in this version */
{
  /* fetch GPRs and special registers from the first register section
     in core bfd. */
  if (which == 0)
    {
      /* copy GPRs first. */
      memcpy (registers, core_reg_sect, 32 * 4);

      /* gdb's internal register template and bfd's register section layout
	 should share a common include file. FIXMEmgo */
      /* then comes special registes. They are supposed to be in the same
	 order in gdb template and bfd `.reg' section. */
      core_reg_sect += (32 * 4);
      memcpy (&registers [REGISTER_BYTE (FIRST_SP_REGNUM)], core_reg_sect, 
	      (LAST_SP_REGNUM - FIRST_SP_REGNUM + 1) * 4);
    }

  /* fetch floating point registers from register section 2 in core bfd. */
  else if (which == 2)
    memcpy (&registers [REGISTER_BYTE (FP0_REGNUM)], core_reg_sect, 32 * 8);

  else
    fprintf_unfiltered (gdb_stderr, "Gdb error: unknown parameter to fetch_core_registers().\n");
}

/* handle symbol translation on vmapping */

static void
vmap_symtab (vp)
     register struct vmap *vp;
{
  register struct objfile *objfile;
  asection *textsec;
  asection *datasec;
  asection *bsssec;
  CORE_ADDR text_delta;
  CORE_ADDR data_delta;
  CORE_ADDR bss_delta;
  struct section_offsets *new_offsets;
  int i;
  
  objfile = vp->objfile;
  if (objfile == NULL)
    {
      /* OK, it's not an objfile we opened ourselves.
	 Currently, that can only happen with the exec file, so
	 relocate the symbols for the symfile.  */
      if (symfile_objfile == NULL)
	return;
      objfile = symfile_objfile;
    }

  new_offsets = alloca
    (sizeof (struct section_offsets)
     + sizeof (new_offsets->offsets) * objfile->num_sections);

  for (i = 0; i < objfile->num_sections; ++i)
    ANOFFSET (new_offsets, i) = ANOFFSET (objfile->section_offsets, i);
  
  textsec = bfd_get_section_by_name (vp->bfd, ".text");
  text_delta =
    vp->tstart - ANOFFSET (objfile->section_offsets, textsec->target_index);
  ANOFFSET (new_offsets, textsec->target_index) = vp->tstart;

  datasec = bfd_get_section_by_name (vp->bfd, ".data");
  data_delta =
    vp->dstart - ANOFFSET (objfile->section_offsets, datasec->target_index);
  ANOFFSET (new_offsets, datasec->target_index) = vp->dstart;
  
  bsssec = bfd_get_section_by_name (vp->bfd, ".bss");
  bss_delta =
    vp->dstart - ANOFFSET (objfile->section_offsets, bsssec->target_index);
  ANOFFSET (new_offsets, bsssec->target_index) = vp->dstart;

  objfile_relocate (objfile, new_offsets);

  {
    struct obj_section *s;
    for (s = objfile->sections; s < objfile->sections_end; ++s)
      {
	if (s->the_bfd_section->target_index == textsec->target_index)
	  {
	    s->addr += text_delta;
	    s->endaddr += text_delta;
	  }
	else if (s->the_bfd_section->target_index == datasec->target_index)
	  {
	    s->addr += data_delta;
	    s->endaddr += data_delta;
	  }
	else if (s->the_bfd_section->target_index == bsssec->target_index)
	  {
	    s->addr += bss_delta;
	    s->endaddr += bss_delta;
	  }
      }
  }
  
  if (text_delta != 0)
    /* breakpoints need to be relocated as well. */
    fixup_breakpoints (0, TEXT_SEGMENT_BASE, text_delta);
}

/* Add symbols for an objfile.  */

static int
objfile_symbol_add (arg)
     char *arg;
{
  struct objfile *obj = (struct objfile *) arg;

  syms_from_objfile (obj, 0, 0, 0);
  new_symfile_objfile (obj, 0, 0);
  return 1;
}

/* Add a new vmap entry based on ldinfo() information.

   If ldi->ldinfo_fd is not valid (e.g. this struct ld_info is from a
   core file), the caller should set it to -1, and we will open the file.

   Return the vmap new entry.  */

static struct vmap *
add_vmap (ldi)
     register struct ld_info *ldi; 
{
  bfd *abfd, *last;
  register char *mem, *objname;
  struct objfile *obj;
  struct vmap *vp;

  /* This ldi structure was allocated using alloca() in 
     xcoff_relocate_symtab(). Now we need to have persistent object 
     and member names, so we should save them. */

  mem = ldi->ldinfo_filename + strlen (ldi->ldinfo_filename) + 1;
  mem = savestring (mem, strlen (mem));
  objname = savestring (ldi->ldinfo_filename, strlen (ldi->ldinfo_filename));

  if (ldi->ldinfo_fd < 0)
    /* Note that this opens it once for every member; a possible
       enhancement would be to only open it once for every object.  */
    abfd = bfd_openr (objname, gnutarget);
  else
    abfd = bfd_fdopenr (objname, gnutarget, ldi->ldinfo_fd);
  if (!abfd)
    error ("Could not open `%s' as an executable file: %s",
	   objname, bfd_errmsg (bfd_get_error ()));

  /* make sure we have an object file */

  if (bfd_check_format (abfd, bfd_object))
    vp = map_vmap (abfd, 0);

  else if (bfd_check_format (abfd, bfd_archive))
    {
      last = 0;
      /* FIXME??? am I tossing BFDs?  bfd? */
      while ((last = bfd_openr_next_archived_file (abfd, last)))
	if (STREQ (mem, last->filename))
	  break;

      if (!last)
	{
	  bfd_close (abfd);
	  /* FIXME -- should be error */
	  warning ("\"%s\": member \"%s\" missing.", abfd->filename, mem);
	  return;
	}

      if (!bfd_check_format(last, bfd_object))
	{
	  bfd_close (last);	/* XXX???	*/
	  goto obj_err;
	}

      vp = map_vmap (last, abfd);
    }
  else
    {
    obj_err:
      bfd_close (abfd);
      error ("\"%s\": not in executable format: %s.",
	     objname, bfd_errmsg (bfd_get_error ()));
      /*NOTREACHED*/
    }
  obj = allocate_objfile (vp->bfd, 0);
  vp->objfile = obj;

#ifndef SOLIB_SYMBOLS_MANUAL
  if (catch_errors (objfile_symbol_add, (char *)obj,
		    "Error while reading shared library symbols:\n",
		    RETURN_MASK_ALL))
    {
      /* Note this is only done if symbol reading was successful.  */
      vmap_symtab (vp);
      vp->loaded = 1;
    }
#endif
  return vp;
}

/* update VMAP info with ldinfo() information
   Input is ptr to ldinfo() results.  */

static void
vmap_ldinfo (ldi)
     register struct ld_info *ldi;
{
  struct stat ii, vi;
  register struct vmap *vp;
  register got_one, retried;
  CORE_ADDR ostart;

  /* For each *ldi, see if we have a corresponding *vp.
     If so, update the mapping, and symbol table.
     If not, add an entry and symbol table.  */

  do {
    char *name = ldi->ldinfo_filename;
    char *memb = name + strlen(name) + 1;

    retried = 0;

    if (fstat (ldi->ldinfo_fd, &ii) < 0)
      fatal ("cannot fstat(fd=%d) on %s", ldi->ldinfo_fd, name);
  retry:
    for (got_one = 0, vp = vmap; vp; vp = vp->nxt)
      {
	FILE *io;

	/* First try to find a `vp', which is the same as in ldinfo.
	   If not the same, just continue and grep the next `vp'. If same,
	   relocate its tstart, tend, dstart, dend values. If no such `vp'
	   found, get out of this for loop, add this ldi entry as a new vmap
	   (add_vmap) and come back, fins its `vp' and so on... */

	/* The filenames are not always sufficient to match on. */

	if ((name[0] == '/' && !STREQ(name, vp->name))
	    || (memb[0] && !STREQ(memb, vp->member)))
	  continue;

	io = bfd_cache_lookup (vp->bfd);		/* totally opaque! */
	if (!io)
	  fatal ("cannot find BFD's iostream for %s", vp->name);

	/* See if we are referring to the same file. */
	/* An error here is innocuous, most likely meaning that
	   the file descriptor has become worthless. */
	if (fstat (fileno(io), &vi) < 0)
	  continue;

	if (ii.st_dev != vi.st_dev || ii.st_ino != vi.st_ino)
	  continue;

	if (!retried)
	  close (ldi->ldinfo_fd);

	++got_one;

	/* found a corresponding VMAP. remap! */
	ostart = vp->tstart;

	/* We can assume pointer == CORE_ADDR, this code is native only.  */
	vp->tstart = (CORE_ADDR) ldi->ldinfo_textorg;
	vp->tend   = vp->tstart + ldi->ldinfo_textsize;
	vp->dstart = (CORE_ADDR) ldi->ldinfo_dataorg;
	vp->dend   = vp->dstart + ldi->ldinfo_datasize;

	if (vp->tadj)
	  {
	    vp->tstart += vp->tadj;
	    vp->tend   += vp->tadj;
	  }

	/* relocate symbol table(s). */
	vmap_symtab (vp);

	/* there may be more, so we don't break out of the loop. */
      }

    /* if there was no matching *vp, we must perforce create the sucker(s) */
    if (!got_one && !retried)
      {
	add_vmap (ldi);
	++retried;
	goto retry;
      }
  } while (ldi->ldinfo_next
	   && (ldi = (void *) (ldi->ldinfo_next + (char *) ldi)));

}

/* As well as symbol tables, exec_sections need relocation. After
   the inferior process' termination, there will be a relocated symbol
   table exist with no corresponding inferior process. At that time, we
   need to use `exec' bfd, rather than the inferior process's memory space
   to look up symbols.

   `exec_sections' need to be relocated only once, as long as the exec
   file remains unchanged.
*/

static void
vmap_exec ()
{
  static bfd *execbfd;
  int i;

  if (execbfd == exec_bfd)
    return;

  execbfd = exec_bfd;

  if (!vmap || !exec_ops.to_sections)
    error ("vmap_exec: vmap or exec_ops.to_sections == 0\n");

  for (i=0; &exec_ops.to_sections[i] < exec_ops.to_sections_end; i++)
    {
      if (STREQ(".text", exec_ops.to_sections[i].the_bfd_section->name))
	{
	  exec_ops.to_sections[i].addr += vmap->tstart;
	  exec_ops.to_sections[i].endaddr += vmap->tstart;
	}
      else if (STREQ(".data", exec_ops.to_sections[i].the_bfd_section->name))
	{
	  exec_ops.to_sections[i].addr += vmap->dstart;
	  exec_ops.to_sections[i].endaddr += vmap->dstart;
	}
    }
}

/* xcoff_relocate_symtab -	hook for symbol table relocation.
   also reads shared libraries.. */

void
xcoff_relocate_symtab (pid)
     unsigned int pid;
{
#define	MAX_LOAD_SEGS 64		/* maximum number of load segments */

  struct ld_info *ldi;

  ldi = (void *) alloca(MAX_LOAD_SEGS * sizeof (*ldi));

  /* According to my humble theory, AIX has some timing problems and
     when the user stack grows, kernel doesn't update stack info in time
     and ptrace calls step on user stack. That is why we sleep here a little,
     and give kernel to update its internals. */

  usleep (36000);

  errno = 0;
  ptrace (PT_LDINFO, pid, (PTRACE_ARG3_TYPE) ldi,
	  MAX_LOAD_SEGS * sizeof(*ldi), ldi);
  if (errno)
    perror_with_name ("ptrace ldinfo");

  vmap_ldinfo (ldi);

  do {
    /* We are allowed to assume CORE_ADDR == pointer.  This code is
       native only.  */
    add_text_to_loadinfo ((CORE_ADDR) ldi->ldinfo_textorg,
			  (CORE_ADDR) ldi->ldinfo_dataorg);
  } while (ldi->ldinfo_next
	   && (ldi = (void *) (ldi->ldinfo_next + (char *) ldi)));

#if 0
  /* Now that we've jumbled things around, re-sort them.  */
  sort_minimal_symbols ();
#endif

  /* relocate the exec and core sections as well. */
  vmap_exec ();
}

/* Core file stuff.  */

/* Relocate symtabs and read in shared library info, based on symbols
   from the core file.  */

void
xcoff_relocate_core ()
{
/* Offset of member MEMBER in a struct of type TYPE.  */
#ifndef offsetof
#define offsetof(TYPE, MEMBER) ((int) &((TYPE *)0)->MEMBER)
#endif

/* Size of a struct ld_info except for the variable-length filename.  */
#define LDINFO_SIZE (offsetof (struct ld_info, ldinfo_filename))

  sec_ptr ldinfo_sec;
  int offset = 0;
  struct ld_info *ldip;
  struct vmap *vp;

  /* Allocated size of buffer.  */
  int buffer_size = LDINFO_SIZE;
  char *buffer = xmalloc (buffer_size);
  struct cleanup *old = make_cleanup (free_current_contents, &buffer);
    
  /* FIXME, this restriction should not exist.  For now, though I'll
     avoid coredumps with error() pending a real fix.  */
  if (vmap == NULL)
    error
      ("Can't debug a core file without an executable file (on the RS/6000)");
  
  ldinfo_sec = bfd_get_section_by_name (core_bfd, ".ldinfo");
  if (ldinfo_sec == NULL)
    {
    bfd_err:
      fprintf_filtered (gdb_stderr, "Couldn't get ldinfo from core file: %s\n",
			bfd_errmsg (bfd_get_error ()));
      do_cleanups (old);
      return;
    }
  do
    {
      int i;
      int names_found = 0;

      /* Read in everything but the name.  */
      if (bfd_get_section_contents (core_bfd, ldinfo_sec, buffer,
				    offset, LDINFO_SIZE) == 0)
	goto bfd_err;

      /* Now the name.  */
      i = LDINFO_SIZE;
      do
	{
	  if (i == buffer_size)
	    {
	      buffer_size *= 2;
	      buffer = xrealloc (buffer, buffer_size);
	    }
	  if (bfd_get_section_contents (core_bfd, ldinfo_sec, &buffer[i],
					offset + i, 1) == 0)
	    goto bfd_err;
	  if (buffer[i++] == '\0')
	    ++names_found;
	} while (names_found < 2);

      ldip = (struct ld_info *) buffer;

      /* Can't use a file descriptor from the core file; need to open it.  */
      ldip->ldinfo_fd = -1;
      
      /* The first ldinfo is for the exec file, allocated elsewhere.  */
      if (offset == 0)
	vp = vmap;
      else
	vp = add_vmap (ldip);

      offset += ldip->ldinfo_next;

      /* We can assume pointer == CORE_ADDR, this code is native only.  */
      vp->tstart = (CORE_ADDR) ldip->ldinfo_textorg;
      vp->tend = vp->tstart + ldip->ldinfo_textsize;
      vp->dstart = (CORE_ADDR) ldip->ldinfo_dataorg;
      vp->dend = vp->dstart + ldip->ldinfo_datasize;

      if (vp->tadj != 0)
	{
	  vp->tstart += vp->tadj;
	  vp->tend += vp->tadj;
	}

      /* Unless this is the exec file,
	 add our sections to the section table for the core target.  */
      if (vp != vmap)
	{
	  int count;
	  struct section_table *stp;
	  
	  count = core_ops.to_sections_end - core_ops.to_sections;
	  count += 2;
	  core_ops.to_sections = (struct section_table *)
	    xrealloc (core_ops.to_sections,
		      sizeof (struct section_table) * count);
	  core_ops.to_sections_end = core_ops.to_sections + count;
	  stp = core_ops.to_sections_end - 2;

	  /* "Why do we add bfd_section_vma?", I hear you cry.
	     Well, the start of the section in the file is actually
	     that far into the section as the struct vmap understands it.
	     So for text sections, bfd_section_vma tends to be 0x200,
	     and if vp->tstart is 0xd0002000, then the first byte of
	     the text section on disk corresponds to address 0xd0002200.  */
	  stp->bfd = vp->bfd;
	  stp->the_bfd_section = bfd_get_section_by_name (stp->bfd, ".text");
	  stp->addr = bfd_section_vma (stp->bfd, stp->the_bfd_section) + vp->tstart;
	  stp->endaddr = bfd_section_vma (stp->bfd, stp->the_bfd_section) + vp->tend;
	  stp++;
	  
	  stp->bfd = vp->bfd;
	  stp->the_bfd_section = bfd_get_section_by_name (stp->bfd, ".data");
	  stp->addr = bfd_section_vma (stp->bfd, stp->the_bfd_section) + vp->dstart;
	  stp->endaddr = bfd_section_vma (stp->bfd, stp->the_bfd_section) + vp->dend;
	}

      vmap_symtab (vp);

      add_text_to_loadinfo ((CORE_ADDR)ldip->ldinfo_textorg,
			    (CORE_ADDR)ldip->ldinfo_dataorg);
    } while (ldip->ldinfo_next != 0);
  vmap_exec ();
  do_cleanups (old);
}