summaryrefslogtreecommitdiff
path: root/gdb/regcache.c
blob: 953892c73f853757f90caa9ed02a31098c84c26a (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
/* Cache and manage the values of registers for GDB, the GNU debugger.
   Copyright 1986, 87, 89, 91, 94, 95, 96, 1998, 2000, 2001
   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 "frame.h"
#include "inferior.h"
#include "target.h"
#include "gdbarch.h"
#include "gdbcmd.h"

/*
 * DATA STRUCTURE
 *
 * Here is the actual register cache.
 */

/* NOTE: this is a write-through cache.  There is no "dirty" bit for
   recording if the register values have been changed (eg. by the
   user).  Therefore all registers must be written back to the
   target when appropriate.  */

/* REGISTERS contains the cached register values (in target byte order). */

char *registers;

/* REGISTER_VALID is 0 if the register needs to be fetched,
                     1 if it has been fetched, and
		    -1 if the register value was not available.  
   "Not available" means don't try to fetch it again.  */

signed char *register_valid;

/* The thread/process associated with the current set of registers.
   For now, -1 is special, and means `no current process'.  */

static int registers_pid = -1;

/*
 * FUNCTIONS:
 */

/* REGISTER_CACHED()

   Returns 0 if the value is not in the cache (needs fetch).
          >0 if the value is in the cache.
	  <0 if the value is permanently unavailable (don't ask again).  */

int
register_cached (int regnum)
{
  return register_valid[regnum];
}

/* Record that REGNUM's value is cached if STATE is >0, uncached but
   fetchable if STATE is 0, and uncached and unfetchable if STATE is <0.  */

void
set_register_cached (int regnum, int state)
{
  register_valid[regnum] = state;
}

/* REGISTER_CHANGED

   invalidate a single register REGNUM in the cache */
void
register_changed (int regnum)
{
  set_register_cached (regnum, 0);
}

/* If REGNUM >= 0, return a pointer to register REGNUM's cache buffer area,
   else return a pointer to the start of the cache buffer.  */

char *
register_buffer (int regnum)
{
  if (regnum < 0)
    return registers;
  else
    return &registers[REGISTER_BYTE (regnum)];
}

/* Return whether register REGNUM is a real register.  */

static int
real_register (int regnum)
{
  return regnum >= 0 && regnum < NUM_REGS;
}

/* Return whether register REGNUM is a pseudo register.  */

static int
pseudo_register (int regnum)
{
  return regnum >= NUM_REGS && regnum < NUM_REGS + NUM_PSEUDO_REGS;
}

/* Fetch register REGNUM into the cache.  */

static void
fetch_register (int regnum)
{
  if (real_register (regnum))
    target_fetch_registers (regnum);
  else if (pseudo_register (regnum))
    FETCH_PSEUDO_REGISTER (regnum);
}

/* Write register REGNUM cached value to the target.  */

static void
store_register (int regnum)
{
  if (real_register (regnum))
    target_store_registers (regnum);
  else if (pseudo_register (regnum))
    STORE_PSEUDO_REGISTER (regnum);
}

/* Low level examining and depositing of registers.

   The caller is responsible for making sure that the inferior is
   stopped before calling the fetching routines, or it will get
   garbage.  (a change from GDB version 3, in which the caller got the
   value from the last stop).  */

/* REGISTERS_CHANGED ()

   Indicate that registers may have changed, so invalidate the cache.  */

void
registers_changed (void)
{
  int i;

  registers_pid = -1;

  /* Force cleanup of any alloca areas if using C alloca instead of
     a builtin alloca.  This particular call is used to clean up
     areas allocated by low level target code which may build up
     during lengthy interactions between gdb and the target before
     gdb gives control to the user (ie watchpoints).  */
  alloca (0);

  for (i = 0; i < ARCH_NUM_REGS; i++)
    set_register_cached (i, 0);

  /* Assume that if all the hardware regs have changed, 
     then so have the pseudo-registers.  */
  for (i = NUM_REGS; i < NUM_REGS + NUM_PSEUDO_REGS; i++)
    set_register_cached (i, 0);

  if (registers_changed_hook)
    registers_changed_hook ();
}

/* REGISTERS_FETCHED ()

   Indicate that all registers have been fetched, so mark them all valid.  */


void
registers_fetched (void)
{
  int i;

  for (i = 0; i < ARCH_NUM_REGS; i++)
    set_register_cached (i, 1);
  /* Do not assume that the pseudo-regs have also been fetched.
     Fetching all real regs might not account for all pseudo-regs.  */
}

/* read_register_bytes and write_register_bytes are generally a *BAD*
   idea.  They are inefficient because they need to check for partial
   updates, which can only be done by scanning through all of the
   registers and seeing if the bytes that are being read/written fall
   inside of an invalid register.  [The main reason this is necessary
   is that register sizes can vary, so a simple index won't suffice.]
   It is far better to call read_register_gen and write_register_gen
   if you want to get at the raw register contents, as it only takes a
   regnum as an argument, and therefore can't do a partial register
   update.

   Prior to the recent fixes to check for partial updates, both read
   and write_register_bytes always checked to see if any registers
   were stale, and then called target_fetch_registers (-1) to update
   the whole set.  This caused really slowed things down for remote
   targets.  */

/* Copy INLEN bytes of consecutive data from registers
   starting with the INREGBYTE'th byte of register data
   into memory at MYADDR.  */

void
read_register_bytes (int inregbyte, char *myaddr, int inlen)
{
  int inregend = inregbyte + inlen;
  int regnum;

  if (registers_pid != inferior_pid)
    {
      registers_changed ();
      registers_pid = inferior_pid;
    }

  /* See if we are trying to read bytes from out-of-date registers.  If so,
     update just those registers.  */

  for (regnum = 0; regnum < NUM_REGS + NUM_PSEUDO_REGS; regnum++)
    {
      int regstart, regend;

      if (register_cached (regnum))
	continue;

      if (REGISTER_NAME (regnum) == NULL || *REGISTER_NAME (regnum) == '\0')
	continue;

      regstart = REGISTER_BYTE (regnum);
      regend = regstart + REGISTER_RAW_SIZE (regnum);

      if (regend <= inregbyte || inregend <= regstart)
	/* The range the user wants to read doesn't overlap with regnum.  */
	continue;

      /* We've found an uncached register where at least one byte will be read.
         Update it from the target.  */
      fetch_register (regnum);

      if (!register_cached (regnum))
	{
	  /* Sometimes pseudoregs are never marked valid, so that they 
	     will be fetched every time (it can be complicated to know
	     if a pseudoreg is valid, while "fetching" them can be cheap). 
	     */
	  if (regnum < NUM_REGS)
 	    error ("read_register_bytes:  Couldn't update register %d.", regnum);
	}
    }

  if (myaddr != NULL)
    memcpy (myaddr, register_buffer (-1) + inregbyte, inlen);
}

/* Read register REGNUM into memory at MYADDR, which must be large
   enough for REGISTER_RAW_BYTES (REGNUM).  Target byte-order.  If the
   register is known to be the size of a CORE_ADDR or smaller,
   read_register can be used instead.  */

void
read_register_gen (int regnum, char *myaddr)
{
  if (registers_pid != inferior_pid)
    {
      registers_changed ();
      registers_pid = inferior_pid;
    }

  if (!register_cached (regnum))
    fetch_register (regnum);

  memcpy (myaddr, register_buffer (regnum),
	  REGISTER_RAW_SIZE (regnum));
}

/* Write register REGNUM at MYADDR to the target.  MYADDR points at
   REGISTER_RAW_BYTES(REGNUM), which must be in target byte-order.  */

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

void
write_register_gen (int regnum, char *myaddr)
{
  int size;

  /* On the sparc, writing %g0 is a no-op, so we don't even want to
     change the registers array if something writes to this register.  */
  if (CANNOT_STORE_REGISTER (regnum))
    return;

  if (registers_pid != inferior_pid)
    {
      registers_changed ();
      registers_pid = inferior_pid;
    }

  size = REGISTER_RAW_SIZE (regnum);

  /* If we have a valid copy of the register, and new value == old value,
     then don't bother doing the actual store. */

  if (register_cached (regnum)
      && memcmp (register_buffer (regnum), myaddr, size) == 0)
    return;

  if (real_register (regnum))
    target_prepare_to_store ();

  memcpy (register_buffer (regnum), myaddr, size);

  set_register_cached (regnum, 1);
  store_register (regnum);
}

/* Copy INLEN bytes of consecutive data from memory at MYADDR
   into registers starting with the MYREGSTART'th byte of register data.  */

void
write_register_bytes (int myregstart, char *myaddr, int inlen)
{
  int myregend = myregstart + inlen;
  int regnum;

  target_prepare_to_store ();

  /* Scan through the registers updating any that are covered by the
     range myregstart<=>myregend using write_register_gen, which does
     nice things like handling threads, and avoiding updates when the
     new and old contents are the same.  */

  for (regnum = 0; regnum < NUM_REGS + NUM_PSEUDO_REGS; regnum++)
    {
      int regstart, regend;

      regstart = REGISTER_BYTE (regnum);
      regend = regstart + REGISTER_RAW_SIZE (regnum);

      /* Is this register completely outside the range the user is writing?  */
      if (myregend <= regstart || regend <= myregstart)
	/* do nothing */ ;		

      /* Is this register completely within the range the user is writing?  */
      else if (myregstart <= regstart && regend <= myregend)
	write_register_gen (regnum, myaddr + (regstart - myregstart));

      /* The register partially overlaps the range being written.  */
      else
	{
	  char *regbuf = (char*) alloca (MAX_REGISTER_RAW_SIZE);
	  /* What's the overlap between this register's bytes and
             those the caller wants to write?  */
	  int overlapstart = max (regstart, myregstart);
	  int overlapend   = min (regend,   myregend);

	  /* We may be doing a partial update of an invalid register.
	     Update it from the target before scribbling on it.  */
	  read_register_gen (regnum, regbuf);

	  memcpy (registers + overlapstart,
		  myaddr + (overlapstart - myregstart),
		  overlapend - overlapstart);

	  store_register (regnum);
	}
    }
}


/* Return the contents of register REGNUM as an unsigned integer.  */

ULONGEST
read_register (int regnum)
{
  if (registers_pid != inferior_pid)
    {
      registers_changed ();
      registers_pid = inferior_pid;
    }

  if (!register_cached (regnum))
    fetch_register (regnum);

  return (extract_unsigned_integer (register_buffer (regnum),
				    REGISTER_RAW_SIZE (regnum)));
}

ULONGEST
read_register_pid (int regnum, int pid)
{
  int save_pid;
  CORE_ADDR retval;

  if (pid == inferior_pid)
    return read_register (regnum);

  save_pid = inferior_pid;

  inferior_pid = pid;

  retval = read_register (regnum);

  inferior_pid = save_pid;

  return retval;
}

/* Return the contents of register REGNUM as a signed integer.  */

LONGEST
read_signed_register (int regnum)
{
  if (registers_pid != inferior_pid)
    {
      registers_changed ();
      registers_pid = inferior_pid;
    }

  if (!register_cached (regnum))
    fetch_register (regnum);

  return (extract_signed_integer (register_buffer (regnum),
				  REGISTER_RAW_SIZE (regnum)));
}

LONGEST
read_signed_register_pid (int regnum, int pid)
{
  int save_pid;
  LONGEST retval;

  if (pid == inferior_pid)
    return read_signed_register (regnum);

  save_pid = inferior_pid;

  inferior_pid = pid;

  retval = read_signed_register (regnum);

  inferior_pid = save_pid;

  return retval;
}

/* Store VALUE into the raw contents of register number REGNUM.  */

void
write_register (int regnum, LONGEST val)
{
  PTR buf;
  int size;

  /* On the sparc, writing %g0 is a no-op, so we don't even want to
     change the registers array if something writes to this register.  */
  if (CANNOT_STORE_REGISTER (regnum))
    return;

  if (registers_pid != inferior_pid)
    {
      registers_changed ();
      registers_pid = inferior_pid;
    }

  size = REGISTER_RAW_SIZE (regnum);
  buf = alloca (size);
  store_signed_integer (buf, size, (LONGEST) val);

  /* If we have a valid copy of the register, and new value == old value,
     then don't bother doing the actual store. */

  if (register_cached (regnum)
      && memcmp (register_buffer (regnum), buf, size) == 0)
    return;

  if (real_register (regnum))
    target_prepare_to_store ();

  memcpy (register_buffer (regnum), buf, size);

  set_register_cached (regnum, 1);
  store_register (regnum);
}

void
write_register_pid (int regnum, CORE_ADDR val, int pid)
{
  int save_pid;

  if (pid == inferior_pid)
    {
      write_register (regnum, val);
      return;
    }

  save_pid = inferior_pid;

  inferior_pid = pid;

  write_register (regnum, val);

  inferior_pid = save_pid;
}

/* SUPPLY_REGISTER()

   Record that register REGNUM contains VAL.  This is used when the
   value is obtained from the inferior or core dump, so there is no
   need to store the value there.

   If VAL is a NULL pointer, then it's probably an unsupported register.
   We just set its value to all zeros.  We might want to record this
   fact, and report it to the users of read_register and friends.  */

void
supply_register (int regnum, char *val)
{
#if 1
  if (registers_pid != inferior_pid)
    {
      registers_changed ();
      registers_pid = inferior_pid;
    }
#endif

  set_register_cached (regnum, 1);
  if (val)
    memcpy (register_buffer (regnum), val, 
	    REGISTER_RAW_SIZE (regnum));
  else
    memset (register_buffer (regnum), '\000', 
	    REGISTER_RAW_SIZE (regnum));

  /* On some architectures, e.g. HPPA, there are a few stray bits in
     some registers, that the rest of the code would like to ignore.  */

#ifdef CLEAN_UP_REGISTER_VALUE
  CLEAN_UP_REGISTER_VALUE (regnum, register_buffer (regnum));
#endif
}

/* read_pc, write_pc, read_sp, write_sp, read_fp, write_fp, etc.
   Special handling for registers PC, SP, and FP.  */

/* This routine is getting awfully cluttered with #if's.  It's probably
   time to turn this into READ_PC and define it in the tm.h file.
   Ditto for write_pc.

   1999-06-08: The following were re-written so that it assumes the
   existence of a TARGET_READ_PC et.al. macro.  A default generic
   version of that macro is made available where needed.

   Since the ``TARGET_READ_PC'' et.al. macro is going to be controlled
   by the multi-arch framework, it will eventually be possible to
   eliminate the intermediate read_pc_pid().  The client would call
   TARGET_READ_PC directly. (cagney). */

CORE_ADDR
generic_target_read_pc (int pid)
{
#ifdef PC_REGNUM
  if (PC_REGNUM >= 0)
    {
      CORE_ADDR pc_val = ADDR_BITS_REMOVE ((CORE_ADDR) read_register_pid (PC_REGNUM, pid));
      return pc_val;
    }
#endif
  internal_error (__FILE__, __LINE__,
		  "generic_target_read_pc");
  return 0;
}

CORE_ADDR
read_pc_pid (int pid)
{
  int saved_inferior_pid;
  CORE_ADDR pc_val;

  /* In case pid != inferior_pid. */
  saved_inferior_pid = inferior_pid;
  inferior_pid = pid;

  pc_val = TARGET_READ_PC (pid);

  inferior_pid = saved_inferior_pid;
  return pc_val;
}

CORE_ADDR
read_pc (void)
{
  return read_pc_pid (inferior_pid);
}

void
generic_target_write_pc (CORE_ADDR pc, int pid)
{
#ifdef PC_REGNUM
  if (PC_REGNUM >= 0)
    write_register_pid (PC_REGNUM, pc, pid);
  if (NPC_REGNUM >= 0)
    write_register_pid (NPC_REGNUM, pc + 4, pid);
  if (NNPC_REGNUM >= 0)
    write_register_pid (NNPC_REGNUM, pc + 8, pid);
#else
  internal_error (__FILE__, __LINE__,
		  "generic_target_write_pc");
#endif
}

void
write_pc_pid (CORE_ADDR pc, int pid)
{
  int saved_inferior_pid;

  /* In case pid != inferior_pid. */
  saved_inferior_pid = inferior_pid;
  inferior_pid = pid;

  TARGET_WRITE_PC (pc, pid);

  inferior_pid = saved_inferior_pid;
}

void
write_pc (CORE_ADDR pc)
{
  write_pc_pid (pc, inferior_pid);
}

/* Cope with strage ways of getting to the stack and frame pointers */

CORE_ADDR
generic_target_read_sp (void)
{
#ifdef SP_REGNUM
  if (SP_REGNUM >= 0)
    return read_register (SP_REGNUM);
#endif
  internal_error (__FILE__, __LINE__,
		  "generic_target_read_sp");
}

CORE_ADDR
read_sp (void)
{
  return TARGET_READ_SP ();
}

void
generic_target_write_sp (CORE_ADDR val)
{
#ifdef SP_REGNUM
  if (SP_REGNUM >= 0)
    {
      write_register (SP_REGNUM, val);
      return;
    }
#endif
  internal_error (__FILE__, __LINE__,
		  "generic_target_write_sp");
}

void
write_sp (CORE_ADDR val)
{
  TARGET_WRITE_SP (val);
}

CORE_ADDR
generic_target_read_fp (void)
{
#ifdef FP_REGNUM
  if (FP_REGNUM >= 0)
    return read_register (FP_REGNUM);
#endif
  internal_error (__FILE__, __LINE__,
		  "generic_target_read_fp");
}

CORE_ADDR
read_fp (void)
{
  return TARGET_READ_FP ();
}

void
generic_target_write_fp (CORE_ADDR val)
{
#ifdef FP_REGNUM
  if (FP_REGNUM >= 0)
    {
      write_register (FP_REGNUM, val);
      return;
    }
#endif
  internal_error (__FILE__, __LINE__,
		  "generic_target_write_fp");
}

void
write_fp (CORE_ADDR val)
{
  TARGET_WRITE_FP (val);
}

/* ARGSUSED */
static void
reg_flush_command (char *command, int from_tty)
{
  /* Force-flush the register cache.  */
  registers_changed ();
  if (from_tty)
    printf_filtered ("Register cache flushed.\n");
}


static void
build_regcache (void)
{
  /* We allocate some extra slop since we do a lot of memcpy's around
     `registers', and failing-soft is better than failing hard.  */
  int sizeof_registers = REGISTER_BYTES + /* SLOP */ 256;
  int sizeof_register_valid = 
    (NUM_REGS + NUM_PSEUDO_REGS) * sizeof (*register_valid);
  registers = xmalloc (sizeof_registers);
  memset (registers, 0, sizeof_registers);
  register_valid = xmalloc (sizeof_register_valid);
  memset (register_valid, 0, sizeof_register_valid);
}

void
_initialize_regcache (void)
{
  build_regcache ();

  register_gdbarch_swap (&registers, sizeof (registers), NULL);
  register_gdbarch_swap (&register_valid, sizeof (register_valid), NULL);
  register_gdbarch_swap (NULL, 0, build_regcache);

  add_com ("flushregs", class_maintenance, reg_flush_command,
	   "Force gdb to flush its register cache (maintainer command)");
}