aboutsummaryrefslogtreecommitdiff
path: root/gdb/i386-linux-nat.c
blob: 6a3755891753d3ba232ac04464e7687916045137 (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
/* Native-dependent code for Linux running on i386's, for GDB.
   Copyright (C) 1999, 2000 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., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include "defs.h"
#include "inferior.h"
#include "gdbcore.h"

/* For i386_linux_skip_solib_resolver.  */
#include "symtab.h"
#include "symfile.h"
#include "objfiles.h"

#include <sys/ptrace.h>
#include <sys/user.h>
#include <sys/procfs.h>

#ifdef HAVE_SYS_REG_H
#include <sys/reg.h>
#endif

/* Prototypes for supply_gregset etc. */
#include "gregset.h"

/* On Linux, threads are implemented as pseudo-processes, in which
   case we may be tracing more than one process at a time.  In that
   case, inferior_pid will contain the main process ID and the
   individual thread (process) ID mashed together.  These macros are
   used to separate them out.  These definitions should be overridden
   if thread support is included.  */

#if !defined (PIDGET)	/* Default definition for PIDGET/TIDGET.  */
#define PIDGET(PID)	PID
#define TIDGET(PID)	0
#endif


/* The register sets used in Linux ELF core-dumps are identical to the
   register sets in `struct user' that is used for a.out core-dumps,
   and is also used by `ptrace'.  The corresponding types are
   `elf_gregset_t' for the general-purpose registers (with
   `elf_greg_t' the type of a single GP register) and `elf_fpregset_t'
   for the floating-point registers.

   Those types used to be available under the names `gregset_t' and
   `fpregset_t' too, and this file used those names in the past.  But
   those names are now used for the register sets used in the
   `mcontext_t' type, and have a different size and layout.  */

/* Mapping between the general-purpose registers in `struct user'
   format and GDB's register array layout.  */
static int regmap[] = 
{
  EAX, ECX, EDX, EBX,
  UESP, EBP, ESI, EDI,
  EIP, EFL, CS, SS,
  DS, ES, FS, GS
};

/* Which ptrace request retrieves which registers?
   These apply to the corresponding SET requests as well.  */
#define GETREGS_SUPPLIES(regno) \
  (0 <= (regno) && (regno) <= 15)
#define GETFPREGS_SUPPLIES(regno) \
  (FP0_REGNUM <= (regno) && (regno) <= LAST_FPU_CTRL_REGNUM)
#define GETXFPREGS_SUPPLIES(regno) \
  (FP0_REGNUM <= (regno) && (regno) <= MXCSR_REGNUM)

/* Does the current host support the GETREGS request?  */
int have_ptrace_getregs =
#ifdef HAVE_PTRACE_GETREGS
  1
#else
  0
#endif
;

/* Does the current host support the GETXFPREGS request?  The header
   file may or may not define it, and even if it is defined, the
   kernel will return EIO if it's running on a pre-SSE processor.

   PTRACE_GETXFPREGS is a Cygnus invention, since we wrote our own
   Linux kernel patch for SSE support.  That patch may or may not
   actually make it into the official distribution.  If you find that
   years have gone by since this stuff was added, and Linux isn't
   using PTRACE_GETXFPREGS, that means that our patch didn't make it,
   and you can delete this, and the related code.

   My instinct is to attach this to some architecture- or
   target-specific data structure, but really, a particular GDB
   process can only run on top of one kernel at a time.  So it's okay
   for this to be a simple variable.  */
int have_ptrace_getxfpregs =
#ifdef HAVE_PTRACE_GETXFPREGS
  1
#else
  0
#endif
;


/* Fetching registers directly from the U area, one at a time.  */

/* FIXME: kettenis/2000-03-05: This duplicates code from `inptrace.c'.
   The problem is that we define FETCH_INFERIOR_REGISTERS since we
   want to use our own versions of {fetch,store}_inferior_registers
   that use the GETREGS request.  This means that the code in
   `infptrace.c' is #ifdef'd out.  But we need to fall back on that
   code when GDB is running on top of a kernel that doesn't support
   the GETREGS request.  I want to avoid changing `infptrace.c' right
   now.  */

#ifndef PT_READ_U
#define PT_READ_U PTRACE_PEEKUSR
#endif
#ifndef PT_WRITE_U
#define PT_WRITE_U PTRACE_POKEUSR
#endif

/* Default the type of the ptrace transfer to int.  */
#ifndef PTRACE_XFER_TYPE
#define PTRACE_XFER_TYPE int
#endif

/* Registers we shouldn't try to fetch.  */
#if !defined (CANNOT_FETCH_REGISTER)
#define CANNOT_FETCH_REGISTER(regno) 0
#endif

/* Fetch one register.  */

static void
fetch_register (regno)
     int regno;
{
  /* This isn't really an address.  But ptrace thinks of it as one.  */
  CORE_ADDR regaddr;
  char mess[128];		/* For messages */
  register int i;
  unsigned int offset;		/* Offset of registers within the u area.  */
  char buf[MAX_REGISTER_RAW_SIZE];
  int tid;

  if (CANNOT_FETCH_REGISTER (regno))
    {
      memset (buf, '\0', REGISTER_RAW_SIZE (regno));	/* Supply zeroes */
      supply_register (regno, buf);
      return;
    }

  /* Overload thread id onto process id */
  if ((tid = TIDGET (inferior_pid)) == 0)
    tid = inferior_pid;		/* no thread id, just use process id */

  offset = U_REGS_OFFSET;

  regaddr = register_addr (regno, offset);
  for (i = 0; i < REGISTER_RAW_SIZE (regno); i += sizeof (PTRACE_XFER_TYPE))
    {
      errno = 0;
      *(PTRACE_XFER_TYPE *) & buf[i] = ptrace (PT_READ_U, tid,
					       (PTRACE_ARG3_TYPE) regaddr, 0);
      regaddr += sizeof (PTRACE_XFER_TYPE);
      if (errno != 0)
	{
	  sprintf (mess, "reading register %s (#%d)", 
		   REGISTER_NAME (regno), regno);
	  perror_with_name (mess);
	}
    }
  supply_register (regno, buf);
}

/* Fetch register values from the inferior.
   If REGNO is negative, do this for all registers.
   Otherwise, REGNO specifies which register (so we can save time). */

void
old_fetch_inferior_registers (regno)
     int regno;
{
  if (regno >= 0)
    {
      fetch_register (regno);
    }
  else
    {
      for (regno = 0; regno < ARCH_NUM_REGS; regno++)
	{
	  fetch_register (regno);
	}
    }
}

/* Registers we shouldn't try to store.  */
#if !defined (CANNOT_STORE_REGISTER)
#define CANNOT_STORE_REGISTER(regno) 0
#endif

/* Store one register. */

static void
store_register (regno)
     int regno;
{
  /* This isn't really an address.  But ptrace thinks of it as one.  */
  CORE_ADDR regaddr;
  char mess[128];		/* For messages */
  register int i;
  unsigned int offset;		/* Offset of registers within the u area.  */
  int tid;

  if (CANNOT_STORE_REGISTER (regno))
    {
      return;
    }

  /* Overload thread id onto process id */
  if ((tid = TIDGET (inferior_pid)) == 0)
    tid = inferior_pid;		/* no thread id, just use process id */

  offset = U_REGS_OFFSET;

  regaddr = register_addr (regno, offset);
  for (i = 0; i < REGISTER_RAW_SIZE (regno); i += sizeof (PTRACE_XFER_TYPE))
    {
      errno = 0;
      ptrace (PT_WRITE_U, tid, (PTRACE_ARG3_TYPE) regaddr,
	      *(PTRACE_XFER_TYPE *) & registers[REGISTER_BYTE (regno) + i]);
      regaddr += sizeof (PTRACE_XFER_TYPE);
      if (errno != 0)
	{
	  sprintf (mess, "writing register %s (#%d)", 
		   REGISTER_NAME (regno), regno);
	  perror_with_name (mess);
	}
    }
}

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

void
old_store_inferior_registers (regno)
     int regno;
{
  if (regno >= 0)
    {
      store_register (regno);
    }
  else
    {
      for (regno = 0; regno < ARCH_NUM_REGS; regno++)
	{
	  store_register (regno);
	}
    }
}


/* Transfering the general-purpose registers between GDB, inferiors
   and core files.  */

/* Fill GDB's register array with the genereal-purpose register values
   in *GREGSETP.  */

void
supply_gregset (elf_gregset_t *gregsetp)
{
  elf_greg_t *regp = (elf_greg_t *) gregsetp;
  int regi;

  for (regi = 0; regi < NUM_GREGS; regi++)
    supply_register (regi, (char *) (regp + regmap[regi]));
}

/* Convert the valid general-purpose register values in GDB's register
   array to `struct user' format and store them in *GREGSETP.  The
   array VALID indicates which register values are valid.  If VALID is
   NULL, all registers are assumed to be valid.  */

static void
convert_to_gregset (elf_gregset_t *gregsetp, signed char *valid)
{
  elf_greg_t *regp = (elf_greg_t *) gregsetp;
  int regi;

  for (regi = 0; regi < NUM_GREGS; regi++)
    if (! valid || valid[regi])
      *(regp + regmap[regi]) = * (int *) &registers[REGISTER_BYTE (regi)];
}

/* Fill register REGNO (if it is a general-purpose register) in
   *GREGSETPS with the value in GDB's register array.  If REGNO is -1,
   do this for all registers.  */
void
fill_gregset (elf_gregset_t *gregsetp, int regno)
{
  if (regno == -1)
    {
      convert_to_gregset (gregsetp, NULL);
      return;
    }

  if (GETREGS_SUPPLIES (regno))
    {
      signed char valid[NUM_GREGS];

      memset (valid, 0, sizeof (valid));
      valid[regno] = 1;

      convert_to_gregset (gregsetp, valid);
    }
}

#ifdef HAVE_PTRACE_GETREGS

/* Fetch all general-purpose registers from process/thread TID and
   store their values in GDB's register array.  */

static void
fetch_regs (int tid)
{
  elf_gregset_t regs;
  int ret;

  ret = ptrace (PTRACE_GETREGS, tid, 0, (int) &regs);
  if (ret < 0)
    {
      if (errno == EIO)
	{
	  /* The kernel we're running on doesn't support the GETREGS
             request.  Reset `have_ptrace_getregs'.  */
	  have_ptrace_getregs = 0;
	  return;
	}

      warning ("Couldn't get registers.");
      return;
    }

  supply_gregset (&regs);
}

/* Store all valid general-purpose registers in GDB's register array
   into the process/thread specified by TID.  */

static void
store_regs (int tid)
{
  elf_gregset_t regs;
  int ret;

  ret = ptrace (PTRACE_GETREGS, tid, 0, (int) &regs);
  if (ret < 0)
    {
      warning ("Couldn't get registers.");
      return;
    }

  convert_to_gregset (&regs, register_valid);

  ret = ptrace (PTRACE_SETREGS, tid, 0, (int) &regs);
  if (ret < 0)
    {
      warning ("Couldn't write registers.");
      return;
    }
}

#else

static void fetch_regs (int tid) {}
static void store_regs (int tid) {}

#endif


/* Transfering floating-point registers between GDB, inferiors and cores.  */

/* What is the address of st(N) within the floating-point register set F?  */
#define FPREG_ADDR(f, n) ((char *) &(f)->st_space + (n) * 10)

/* Fill GDB's register array with the floating-point register values in
   *FPREGSETP.  */

void 
supply_fpregset (elf_fpregset_t *fpregsetp)
{
  int reg;
  long l;

  /* Supply the floating-point registers.  */
  for (reg = 0; reg < 8; reg++)
    supply_register (FP0_REGNUM + reg, FPREG_ADDR (fpregsetp, reg));

  /* We have to mask off the reserved bits in *FPREGSETP before
     storing the values in GDB's register file.  */
#define supply(REGNO, MEMBER)                                           \
  l = fpregsetp->MEMBER & 0xffff;                                       \
  supply_register (REGNO, (char *) &l)

  supply (FCTRL_REGNUM, cwd);
  supply (FSTAT_REGNUM, swd);
  supply (FTAG_REGNUM, twd);
  supply_register (FCOFF_REGNUM, (char *) &fpregsetp->fip);
  supply (FDS_REGNUM, fos);
  supply_register (FDOFF_REGNUM, (char *) &fpregsetp->foo);

#undef supply

  /* Extract the code segment and opcode from the  "fcs" member.  */
  l = fpregsetp->fcs & 0xffff;
  supply_register (FCS_REGNUM, (char *) &l);

  l = (fpregsetp->fcs >> 16) & ((1 << 11) - 1);
  supply_register (FOP_REGNUM, (char *) &l);
}

/* Convert the valid floating-point register values in GDB's register
   array to `struct user' format and store them in *FPREGSETP.  The
   array VALID indicates which register values are valid.  If VALID is
   NULL, all registers are assumed to be valid.  */

static void
convert_to_fpregset (elf_fpregset_t *fpregsetp, signed char *valid)
{
  int reg;

  /* Fill in the floating-point registers.  */
  for (reg = 0; reg < 8; reg++)
    if (!valid || valid[reg])
      memcpy (FPREG_ADDR (fpregsetp, reg),
	      &registers[REGISTER_BYTE (FP0_REGNUM + reg)],
	      REGISTER_RAW_SIZE(FP0_REGNUM + reg));

  /* We're not supposed to touch the reserved bits in *FPREGSETP.  */

#define fill(MEMBER, REGNO)						\
  if (! valid || valid[(REGNO)])					\
    fpregsetp->MEMBER                                                   \
      = ((fpregsetp->MEMBER & ~0xffff)                                  \
         | (* (int *) &registers[REGISTER_BYTE (REGNO)] & 0xffff))

#define fill_register(MEMBER, REGNO)                                    \
  if (! valid || valid[(REGNO)])                                        \
    memcpy (&fpregsetp->MEMBER, &registers[REGISTER_BYTE (REGNO)],      \
            sizeof (fpregsetp->MEMBER))

  fill (cwd, FCTRL_REGNUM);
  fill (swd, FSTAT_REGNUM);
  fill (twd, FTAG_REGNUM);
  fill_register (fip, FCOFF_REGNUM);
  fill (foo, FDOFF_REGNUM);
  fill_register (fos, FDS_REGNUM);

#undef fill
#undef fill_register

  if (! valid || valid[FCS_REGNUM])
    fpregsetp->fcs
      = ((fpregsetp->fcs & ~0xffff)
	 | (* (int *) &registers[REGISTER_BYTE (FCS_REGNUM)] & 0xffff));

  if (! valid || valid[FOP_REGNUM])
    fpregsetp->fcs
      = ((fpregsetp->fcs & 0xffff)
	 | ((*(int *) &registers[REGISTER_BYTE (FOP_REGNUM)] & ((1 << 11) - 1))
	    << 16));
}

/* Fill register REGNO (if it is a floating-point register) in
   *FPREGSETP with the value in GDB's register array.  If REGNO is -1,
   do this for all registers.  */

void
fill_fpregset (elf_fpregset_t *fpregsetp, int regno)
{
  if (regno == -1)
    {
      convert_to_fpregset (fpregsetp, NULL);
      return;
    }

  if (GETFPREGS_SUPPLIES(regno))
    {
      signed char valid[MAX_NUM_REGS];
      
      memset (valid, 0, sizeof (valid));
      valid[regno] = 1;
	      
      convert_to_fpregset (fpregsetp, valid);
    }
}

#ifdef HAVE_PTRACE_GETREGS

/* Fetch all floating-point registers from process/thread TID and store
   thier values in GDB's register array.  */

static void
fetch_fpregs (int tid)
{
  elf_fpregset_t fpregs;
  int ret;

  ret = ptrace (PTRACE_GETFPREGS, tid, 0, (int) &fpregs);
  if (ret < 0)
    {
      warning ("Couldn't get floating point status.");
      return;
    }

  supply_fpregset (&fpregs);
}

/* Store all valid floating-point registers in GDB's register array
   into the process/thread specified by TID.  */

static void
store_fpregs (int tid)
{
  elf_fpregset_t fpregs;
  int ret;

  ret = ptrace (PTRACE_GETFPREGS, tid, 0, (int) &fpregs);
  if (ret < 0)
    {
      warning ("Couldn't get floating point status.");
      return;
    }

  convert_to_fpregset (&fpregs, register_valid);

  ret = ptrace (PTRACE_SETFPREGS, tid, 0, (int) &fpregs);
  if (ret < 0)
    {
      warning ("Couldn't write floating point status.");
      return;
    }
}

#else

static void fetch_fpregs (int tid) {}
static void store_fpregs (int tid) {}

#endif


/* Transfering floating-point and SSE registers to and from GDB.  */

/* PTRACE_GETXFPREGS is a Cygnus invention, since we wrote our own
   Linux kernel patch for SSE support.  That patch may or may not
   actually make it into the official distribution.  If you find that
   years have gone by since this code was added, and Linux isn't using
   PTRACE_GETXFPREGS, that means that our patch didn't make it, and
   you can delete this code.  */

#ifdef HAVE_PTRACE_GETXFPREGS

/* Fill GDB's register array with the floating-point and SSE register
   values in *XFPREGS.  */

static void
supply_xfpregset (struct user_xfpregs_struct *xfpregs)
{
  int reg;

  /* Supply the floating-point registers.  */
  for (reg = 0; reg < 8; reg++)
    supply_register (FP0_REGNUM + reg, (char *) &xfpregs->st_space[reg]);

  {
    supply_register (FCTRL_REGNUM, (char *) &xfpregs->cwd);
    supply_register (FSTAT_REGNUM, (char *) &xfpregs->swd);
    supply_register (FTAG_REGNUM,  (char *) &xfpregs->twd);
    supply_register (FCOFF_REGNUM, (char *) &xfpregs->fip);
    supply_register (FDS_REGNUM,   (char *) &xfpregs->fos);
    supply_register (FDOFF_REGNUM, (char *) &xfpregs->foo);
  
    /* Extract the code segment and opcode from the  "fcs" member.  */
    {
      long l;
      
      l = xfpregs->fcs & 0xffff;
      supply_register (FCS_REGNUM, (char *) &l);

      l = (xfpregs->fcs >> 16) & ((1 << 11) - 1);
      supply_register (FOP_REGNUM, (char *) &l);
    }
  }

  /* Supply the SSE registers.  */
  for (reg = 0; reg < 8; reg++)
    supply_register (XMM0_REGNUM + reg, (char *) &xfpregs->xmm_space[reg]);
  supply_register (MXCSR_REGNUM, (char *) &xfpregs->mxcsr);
}

/* Convert the valid floating-point and SSE registers in GDB's
   register array to `struct user' format and store them in *XFPREGS.
   The array VALID indicates which registers are valid.  If VALID is
   NULL, all registers are assumed to be valid.  */

static void
convert_to_xfpregset (struct user_xfpregs_struct *xfpregs,
		      signed char *valid)
{
  int reg;

  /* Fill in the floating-point registers.  */
  for (reg = 0; reg < 8; reg++)
    if (!valid || valid[reg])
      memcpy (&xfpregs->st_space[reg],
	      &registers[REGISTER_BYTE (FP0_REGNUM + reg)],
	      REGISTER_RAW_SIZE(FP0_REGNUM + reg));

#define fill(MEMBER, REGNO)						\
  if (! valid || valid[(REGNO)])					\
    memcpy (&xfpregs->MEMBER, &registers[REGISTER_BYTE (REGNO)],	\
	    sizeof (xfpregs->MEMBER))

  fill (cwd, FCTRL_REGNUM);
  fill (swd, FSTAT_REGNUM);
  fill (twd, FTAG_REGNUM);
  fill (fip, FCOFF_REGNUM);
  fill (foo, FDOFF_REGNUM);
  fill (fos, FDS_REGNUM);

#undef fill

  if (! valid || valid[FCS_REGNUM])
    xfpregs->fcs
      = ((xfpregs->fcs & ~0xffff)
	 | (* (int *) &registers[REGISTER_BYTE (FCS_REGNUM)] & 0xffff));

  if (! valid || valid[FOP_REGNUM])
    xfpregs->fcs
      = ((xfpregs->fcs & 0xffff)
	 | ((*(int *) &registers[REGISTER_BYTE (FOP_REGNUM)] & ((1 << 11) - 1))
	    << 16));

  /* Fill in the XMM registers.  */
  for (reg = 0; reg < 8; reg++)
    if (! valid || valid[reg])
      memcpy (&xfpregs->xmm_space[reg],
	      &registers[REGISTER_BYTE (XMM0_REGNUM + reg)],
	      REGISTER_RAW_SIZE (XMM0_REGNUM + reg));
}

/* Fetch all registers covered by the PTRACE_SETXFPREGS request from
   process/thread TID and store their values in GDB's register array.
   Return non-zero if successful, zero otherwise.  */

static int
fetch_xfpregs (int tid)
{
  struct user_xfpregs_struct xfpregs;
  int ret;

  if (! have_ptrace_getxfpregs) 
    return 0;

  ret = ptrace (PTRACE_GETXFPREGS, tid, 0, &xfpregs);
  if (ret == -1)
    {
      if (errno == EIO)
	{
	  have_ptrace_getxfpregs = 0;
	  return 0;
	}

      warning ("Couldn't read floating-point and SSE registers.");
      return 0;
    }

  supply_xfpregset (&xfpregs);
  return 1;
}

/* Store all valid registers in GDB's register array covered by the
   PTRACE_SETXFPREGS request into the process/thread specified by TID.
   Return non-zero if successful, zero otherwise.  */

static int
store_xfpregs (int tid)
{
  struct user_xfpregs_struct xfpregs;
  int ret;

  if (! have_ptrace_getxfpregs)
    return 0;

  ret = ptrace (PTRACE_GETXFPREGS, tid, 0, &xfpregs);
  if (ret == -1)
    {
      if (errno == EIO)
	{
	  have_ptrace_getxfpregs = 0;
	  return 0;
	}

      warning ("Couldn't read floating-point and SSE registers.");
      return 0;
    }

  convert_to_xfpregset (&xfpregs, register_valid);

  if (ptrace (PTRACE_SETXFPREGS, tid, 0, &xfpregs) < 0)
    {
      warning ("Couldn't write floating-point and SSE registers.");
      return 0;
    }

  return 1;
}

/* Fill the XMM registers in the register array with dummy values.  For
   cases where we don't have access to the XMM registers.  I think
   this is cleaner than printing a warning.  For a cleaner solution,
   we should gdbarchify the i386 family.  */

static void
dummy_sse_values (void)
{
  /* C doesn't have a syntax for NaN's, so write it out as an array of
     longs.  */
  static long dummy[4] = { 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff };
  static long mxcsr = 0x1f80;
  int reg;

  for (reg = 0; reg < 8; reg++)
    supply_register (XMM0_REGNUM + reg, (char *) dummy);
  supply_register (MXCSR_REGNUM, (char *) &mxcsr);
}

#else

/* Stub versions of the above routines, for systems that don't have
   PTRACE_GETXFPREGS.  */
static int store_xfpregs (int tid) { return 0; }
static int fetch_xfpregs (int tid) { return 0; }
static void dummy_sse_values (void) {}

#endif


/* Transferring arbitrary registers between GDB and inferior.  */

/* Fetch register REGNO from the child process.  If REGNO is -1, do
   this for all registers (including the floating point and SSE
   registers).  */

void
fetch_inferior_registers (int regno)
{
  int tid;

  /* Use the old method of peeking around in `struct user' if the
     GETREGS request isn't available.  */
  if (! have_ptrace_getregs)
    {
      old_fetch_inferior_registers (regno);
      return;
    }

  /* Linux LWP ID's are process ID's.  */
  if ((tid = TIDGET (inferior_pid)) == 0)
    tid = inferior_pid;		/* Not a threaded program.  */

  /* Use the PTRACE_GETXFPREGS request whenever possible, since it
     transfers more registers in one system call, and we'll cache the
     results.  But remember that fetch_xfpregs can fail, and return
     zero.  */
  if (regno == -1)
    {
      fetch_regs (tid);

      /* The call above might reset `have_ptrace_getregs'.  */
      if (! have_ptrace_getregs)
	{
	  old_fetch_inferior_registers (-1);
	  return;
	}

      if (fetch_xfpregs (tid))
	return;
      fetch_fpregs (tid);
      return;
    }

  if (GETREGS_SUPPLIES (regno))
    {
      fetch_regs (tid);
      return;
    }

  if (GETXFPREGS_SUPPLIES (regno))
    {
      if (fetch_xfpregs (tid))
	return;

      /* Either our processor or our kernel doesn't support the SSE
	 registers, so read the FP registers in the traditional way,
	 and fill the SSE registers with dummy values.  It would be
	 more graceful to handle differences in the register set using
	 gdbarch.  Until then, this will at least make things work
	 plausibly.  */
      fetch_fpregs (tid);
      dummy_sse_values ();
      return;
    }

  internal_error ("i386-linux-nat.c (fetch_inferior_registers): "
		  "got request for bad register number %d", regno);
}

/* Store register REGNO back into the child process.  If REGNO is -1,
   do this for all registers (including the floating point and SSE
   registers).  */
void
store_inferior_registers (int regno)
{
  int tid;

  /* Use the old method of poking around in `struct user' if the
     SETREGS request isn't available.  */
  if (! have_ptrace_getregs)
    {
      old_store_inferior_registers (regno);
      return;
    }

  /* Linux LWP ID's are process ID's.  */
  if ((tid = TIDGET (inferior_pid)) == 0)
    tid = inferior_pid;		/* Not a threaded program.  */

  /* Use the PTRACE_SETXFPREGS requests whenever possibl, since it
     transfers more registers in one system call.  But remember that
     store_xfpregs can fail, and return zero.  */
  if (regno == -1)
    {
      store_regs (tid);
      if (store_xfpregs (tid))
	return;
      store_fpregs (tid);
      return;
    }

  if (GETREGS_SUPPLIES (regno))
    {
      store_regs (tid);
      return;
    }

  if (GETXFPREGS_SUPPLIES (regno))
    {
      if (store_xfpregs (tid))
	return;

      /* Either our processor or our kernel doesn't support the SSE
	 registers, so just write the FP registers in the traditional
	 way.  */
      store_fpregs (tid);
      return;
    }

  internal_error ("Got request to store bad register number %d.", regno);
}


/* Interpreting register set info found in core files.  */

/* Provide registers to GDB from a core file.

   (We can't use the generic version of this function in
   core-regset.c, because Linux has *three* different kinds of
   register set notes.  core-regset.c would have to call
   supply_xfpregset, which most platforms don't have.)

   CORE_REG_SECT points to an array of bytes, which are the contents
   of a `note' from a core file which BFD thinks might contain
   register contents.  CORE_REG_SIZE is its size.

   WHICH says which register set corelow suspects this is:
     0 --- the general-purpose register set, in elf_gregset_t format
     2 --- the floating-point register set, in elf_fpregset_t format
     3 --- the extended floating-point register set, in struct
           user_xfpregs_struct format

   REG_ADDR isn't used on Linux.  */

static void
fetch_core_registers (char *core_reg_sect, unsigned core_reg_size,
		      int which, CORE_ADDR reg_addr)
{
  elf_gregset_t gregset;
  elf_fpregset_t fpregset;

  switch (which)
    {
    case 0:
      if (core_reg_size != sizeof (gregset))
	warning ("Wrong size gregset in core file.");
      else
	{
	  memcpy (&gregset, core_reg_sect, sizeof (gregset));
	  supply_gregset (&gregset);
	}
      break;

    case 2:
      if (core_reg_size != sizeof (fpregset))
	warning ("Wrong size fpregset in core file.");
      else
	{
	  memcpy (&fpregset, core_reg_sect, sizeof (fpregset));
	  supply_fpregset (&fpregset);
	}
      break;

#ifdef HAVE_PTRACE_GETXFPREGS
      {
	struct user_xfpregs_struct xfpregset;

      case 3:
	if (core_reg_size != sizeof (xfpregset))
	  warning ("Wrong size user_xfpregs_struct in core file.");
	else
	  {
	    memcpy (&xfpregset, core_reg_sect, sizeof (xfpregset));
	    supply_xfpregset (&xfpregset);
	  }
	break;
      }
#endif

    default:
      /* We've covered all the kinds of registers we know about here,
         so this must be something we wouldn't know what to do with
         anyway.  Just ignore it.  */
      break;
    }
}


/* The instruction for a Linux system call is:
       int $0x80
   or 0xcd 0x80.  */

static const unsigned char linux_syscall[] = { 0xcd, 0x80 };

#define LINUX_SYSCALL_LEN (sizeof linux_syscall)

/* The system call number is stored in the %eax register.  */
#define LINUX_SYSCALL_REGNUM 0	/* %eax */

/* We are specifically interested in the sigreturn and rt_sigreturn
   system calls.  */

#ifndef SYS_sigreturn
#define SYS_sigreturn		0x77
#endif
#ifndef SYS_rt_sigreturn
#define SYS_rt_sigreturn	0xad
#endif

/* Offset to saved processor flags, from <asm/sigcontext.h>.  */
#define LINUX_SIGCONTEXT_EFLAGS_OFFSET (64)

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

void
child_resume (int pid, int step, enum target_signal signal)
{
  int request = PTRACE_CONT;

  if (pid == -1)
    /* Resume all threads.  */
    /* I think this only gets used in the non-threaded case, where "resume
       all threads" and "resume inferior_pid" are the same.  */
    pid = inferior_pid;

  if (step)
    {
      CORE_ADDR pc = read_pc_pid (pid);
      unsigned char buf[LINUX_SYSCALL_LEN];

      request = PTRACE_SINGLESTEP;

      /* Returning from a signal trampoline is done by calling a
         special system call (sigreturn or rt_sigreturn, see
         i386-linux-tdep.c for more information).  This system call
         restores the registers that were saved when the signal was
         raised, including %eflags.  That means that single-stepping
         won't work.  Instead, we'll have to modify the signal context
         that's about to be restored, and set the trace flag there.  */

      /* First check if PC is at a system call.  */
      if (read_memory_nobpt (pc, (char *) buf, LINUX_SYSCALL_LEN) == 0
	  && memcmp (buf, linux_syscall, LINUX_SYSCALL_LEN) == 0)
	{
	  int syscall = read_register_pid (LINUX_SYSCALL_REGNUM, pid);

	  /* Then check the system call number.  */
	  if (syscall == SYS_sigreturn || syscall == SYS_rt_sigreturn)
	    {
	      CORE_ADDR sp = read_register (SP_REGNUM);
	      CORE_ADDR addr = sp;
	      unsigned long int eflags;
	      
	      if (syscall == SYS_rt_sigreturn)
		addr = read_memory_integer (sp + 8, 4) + 20;

	      /* Set the trace flag in the context that's about to be
                 restored.  */
	      addr += LINUX_SIGCONTEXT_EFLAGS_OFFSET;
	      read_memory (addr, (char *) &eflags, 4);
	      eflags |= 0x0100;
	      write_memory (addr, (char *) &eflags, 4);
	    }
	}
    }

  if (ptrace (request, pid, 0, target_signal_to_host (signal)) == -1)
    perror_with_name ("ptrace");
}


/* Calling functions in shared libraries.  */
/* FIXME: kettenis/2000-03-05: Doesn't this belong in a
   target-dependent file?  The function
   `i386_linux_skip_solib_resolver' is mentioned in
   `config/i386/tm-linux.h'.  */

/* Find the minimal symbol named NAME, and return both the minsym
   struct and its objfile.  This probably ought to be in minsym.c, but
   everything there is trying to deal with things like C++ and
   SOFUN_ADDRESS_MAYBE_TURQUOISE, ...  Since this is so simple, it may
   be considered too special-purpose for general consumption.  */

static struct minimal_symbol *
find_minsym_and_objfile (char *name, struct objfile **objfile_p)
{
  struct objfile *objfile;

  ALL_OBJFILES (objfile)
    {
      struct minimal_symbol *msym;

      ALL_OBJFILE_MSYMBOLS (objfile, msym)
	{
	  if (SYMBOL_NAME (msym)
	      && STREQ (SYMBOL_NAME (msym), name))
	    {
	      *objfile_p = objfile;
	      return msym;
	    }
	}
    }

  return 0;
}


static CORE_ADDR
skip_hurd_resolver (CORE_ADDR pc)
{
  /* The HURD dynamic linker is part of the GNU C library, so many
     GNU/Linux distributions use it.  (All ELF versions, as far as I
     know.)  An unresolved PLT entry points to "_dl_runtime_resolve",
     which calls "fixup" to patch the PLT, and then passes control to
     the function.

     We look for the symbol `_dl_runtime_resolve', and find `fixup' in
     the same objfile.  If we are at the entry point of `fixup', then
     we set a breakpoint at the return address (at the top of the
     stack), and continue.
  
     It's kind of gross to do all these checks every time we're
     called, since they don't change once the executable has gotten
     started.  But this is only a temporary hack --- upcoming versions
     of Linux will provide a portable, efficient interface for
     debugging programs that use shared libraries.  */

  struct objfile *objfile;
  struct minimal_symbol *resolver 
    = find_minsym_and_objfile ("_dl_runtime_resolve", &objfile);

  if (resolver)
    {
      struct minimal_symbol *fixup
	= lookup_minimal_symbol ("fixup", 0, objfile);

      if (fixup && SYMBOL_VALUE_ADDRESS (fixup) == pc)
	return (SAVED_PC_AFTER_CALL (get_current_frame ()));
    }

  return 0;
}      

/* See the comments for SKIP_SOLIB_RESOLVER at the top of infrun.c.
   This function:
   1) decides whether a PLT has sent us into the linker to resolve
      a function reference, and 
   2) if so, tells us where to set a temporary breakpoint that will
      trigger when the dynamic linker is done.  */

CORE_ADDR
i386_linux_skip_solib_resolver (CORE_ADDR pc)
{
  CORE_ADDR result;

  /* Plug in functions for other kinds of resolvers here.  */
  result = skip_hurd_resolver (pc);
  if (result)
    return result;

  return 0;
}


/* Register that we are able to handle Linux ELF core file formats.  */

static struct core_fns linux_elf_core_fns =
{
  bfd_target_elf_flavour,		/* core_flavour */
  default_check_format,			/* check_format */
  default_core_sniffer,			/* core_sniffer */
  fetch_core_registers,			/* core_read_registers */
  NULL					/* next */
};

void
_initialize_i386_linux_nat ()
{
  add_core_fns (&linux_elf_core_fns);
}