Boot Linux faster!

Check our new training course

Boot Linux faster!

Check our new training course
and Creative Commons CC-BY-SA
lecture and lab materials

Bootlin logo

Elixir Cross Referencer

  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
/* ptrace.c: Sparc process tracing support.
 *
 * Copyright (C) 1996 David S. Miller (davem@caipfs.rutgers.edu)
 *
 * Based upon code written by Ross Biro, Linus Torvalds, Bob Manson,
 * and David Mosberger.
 *
 * Added Linux support -miguel (wierd, eh?, the orignal code was meant
 * to emulate SunOS).
 */

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>

#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/uaccess.h>

#define MAGIC_CONSTANT 0x80000000

/*
 * This routine gets a long from any process space by following the page
 * tables. NOTE! You should check that the long isn't on a page boundary,
 * and that it is in the task area before calling this: this routine does
 * no checking.
 */
static unsigned long get_long(struct task_struct * tsk,
	struct vm_area_struct * vma, unsigned long addr)
{
	pgd_t * pgdir;
	pmd_t * pgmiddle;
	pte_t * pgtable;
	unsigned long page, retval;

repeat:
	pgdir = pgd_offset(vma->vm_mm, addr);
	if (pgd_none(*pgdir)) {
		handle_mm_fault(tsk, vma, addr, 0);
		goto repeat;
	}
	if (pgd_bad(*pgdir)) {
		printk("ptrace: bad page directory %08lx\n", pgd_val(*pgdir));
		pgd_clear(pgdir);
		return 0;
	}
	pgmiddle = pmd_offset(pgdir, addr);
	if (pmd_none(*pgmiddle)) {
		handle_mm_fault(tsk, vma, addr, 0);
		goto repeat;
	}
	if (pmd_bad(*pgmiddle)) {
		printk("ptrace: bad page middle %08lx\n", pmd_val(*pgmiddle));
		pmd_clear(pgmiddle);
		return 0;
	}
	pgtable = pte_offset(pgmiddle, addr);
	if (!pte_present(*pgtable)) {
		handle_mm_fault(tsk, vma, addr, 0);
		goto repeat;
	}
	page = pte_page(*pgtable);
/* this is a hack for non-kernel-mapped video buffers and similar */
	if (MAP_NR(page) >= max_mapnr)
		return 0;
	page += addr & ~PAGE_MASK;
	retval = *(unsigned long *) page;
	flush_page_to_ram(page);
	return retval;
}

/*
 * This routine puts a long into any process space by following the page
 * tables. NOTE! You should check that the long isn't on a page boundary,
 * and that it is in the task area before calling this: this routine does
 * no checking.
 *
 * Now keeps R/W state of page so that a text page stays readonly
 * even if a debugger scribbles breakpoints into it.  -M.U-
 */
static void put_long(struct task_struct * tsk, struct vm_area_struct * vma,
	unsigned long addr, unsigned long data)
{
	pgd_t *pgdir;
	pmd_t *pgmiddle;
	pte_t *pgtable;
	unsigned long page;

repeat:
	pgdir = pgd_offset(vma->vm_mm, addr);
	if (!pgd_present(*pgdir)) {
		handle_mm_fault(tsk, vma, addr, 1);
		goto repeat;
	}
	if (pgd_bad(*pgdir)) {
		printk("ptrace: bad page directory %08lx\n", pgd_val(*pgdir));
		pgd_clear(pgdir);
		return;
	}
	pgmiddle = pmd_offset(pgdir, addr);
	if (pmd_none(*pgmiddle)) {
		handle_mm_fault(tsk, vma, addr, 1);
		goto repeat;
	}
	if (pmd_bad(*pgmiddle)) {
		printk("ptrace: bad page middle %08lx\n", pmd_val(*pgmiddle));
		pmd_clear(pgmiddle);
		return;
	}
	pgtable = pte_offset(pgmiddle, addr);
	if (!pte_present(*pgtable)) {
		handle_mm_fault(tsk, vma, addr, 1);
		goto repeat;
	}
	page = pte_page(*pgtable);
	if (!pte_write(*pgtable)) {
		handle_mm_fault(tsk, vma, addr, 1);
		goto repeat;
	}
/* this is a hack for non-kernel-mapped video buffers and similar */
	flush_cache_page(vma, addr);
	if (MAP_NR(page) < max_mapnr) {
		*(unsigned long *) (page + (addr & ~PAGE_MASK)) = data;
		flush_page_to_ram(page);
	}
/* we're bypassing pagetables, so we have to set the dirty bit ourselves */
/* this should also re-instate whatever read-only mode there was before */
	set_pte(pgtable, pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
	flush_tlb_page(vma, addr);
}

static struct vm_area_struct * find_extend_vma(struct task_struct * tsk,
					       unsigned long addr)
{
	struct vm_area_struct * vma;

	addr &= PAGE_MASK;
	vma = find_vma(tsk->mm,addr);
	if (!vma)
		return NULL;
	if (vma->vm_start <= addr)
		return vma;
	if (!(vma->vm_flags & VM_GROWSDOWN))
		return NULL;
	if (vma->vm_end - addr > tsk->rlim[RLIMIT_STACK].rlim_cur)
		return NULL;
	vma->vm_offset -= vma->vm_start - addr;
	vma->vm_start = addr;
	return vma;
}

/*
 * This routine checks the page boundaries, and that the offset is
 * within the task area. It then calls get_long() to read a long.
 */
static int read_long(struct task_struct * tsk, unsigned long addr,
		     unsigned long * result)
{
	struct vm_area_struct * vma = find_extend_vma(tsk, addr);

	if (!vma)
		return -EIO;
	*result = get_long(tsk, vma, addr);
	return 0;
}

static int read_byte(struct task_struct *tsk, unsigned long addr,
		     unsigned char *result)
{
	struct vm_area_struct *vma = find_extend_vma(tsk, addr&~3);
	unsigned long tmp;

	if(!vma)
		return -EIO;
	tmp = get_long(tsk, vma, (addr & ~3));
	switch(addr & 3) {
	case 0:
		*result = (tmp & 0xff000000)>>24;
		break;
	case 1:
		*result = (tmp & 0x00ff0000)>>16;
		break;
	case 2:
		*result = (tmp & 0x0000ff00)>>8;
		break;
	case 3:
		*result = (tmp & 0x000000ff);
		break;
	}
	return 0;
}

/*
 * This routine checks the page boundaries, and that the offset is
 * within the task area. It then calls put_long() to write a long.
 */
static int write_long(struct task_struct * tsk, unsigned long addr,
		      unsigned long data)
{
	struct vm_area_struct * vma = find_extend_vma(tsk, addr);

	if (!vma)
		return -EIO;
	put_long(tsk, vma, addr, data);
	return 0;
}

static int write_byte(struct task_struct * tsk, unsigned long addr,
		      unsigned char data)
{
	struct vm_area_struct * vma = find_extend_vma(tsk, (addr & ~3));
	unsigned long tmp;

	if (!vma)
		return -EIO;
	tmp = get_long(tsk, vma, (addr & ~3));
	switch(addr & 3) {
	case 0:
		tmp &= 0x00ffffff;
		tmp |= (data << 24);
		break;
	case 1:
		tmp &= 0xff00ffff;
		tmp |= ((data << 16) & 0x00ff0000);
		break;
	case 2:
		tmp &= 0xffff00ff;
		tmp |= ((data << 8) & 0x0000ff00);
		break;
	case 3:
		tmp &= 0xffffff00;
		tmp |= (data & 0x000000ff);
		break;
	}
	put_long(tsk, vma, (addr & ~3), tmp);
	return 0;
}

/* Returning from ptrace is a bit tricky because the syscall return
 * low level code assumes any value returned which is negative and
 * is a valid errno will mean setting the condition codes to indicate
 * an error return.  This doesn't work, so we have this hook.
 */
static inline void pt_error_return(struct pt_regs *regs, unsigned long error)
{
	regs->u_regs[UREG_I0] = error;
	regs->psr |= PSR_C;
	regs->pc = regs->npc;
	regs->npc += 4;
}

static inline void pt_succ_return(struct pt_regs *regs, unsigned long value)
{
	regs->u_regs[UREG_I0] = value;
	regs->psr &= ~PSR_C;
	regs->pc = regs->npc;
	regs->npc += 4;
}

static void
pt_succ_return_linux(struct pt_regs *regs, unsigned long value, long *addr)
{
	if(put_user(value, addr))
		return pt_error_return(regs, EFAULT);
	regs->u_regs[UREG_I0] = 0;
	regs->psr &= ~PSR_C;
	regs->pc = regs->npc;
	regs->npc += 4;
}

static void
pt_os_succ_return (struct pt_regs *regs, unsigned long val, long *addr)
{
	if (current->personality & PER_BSD)
		pt_succ_return (regs, val);
	else
		pt_succ_return_linux (regs, val, addr);
}

/* Fuck me gently with a chainsaw... */
static inline void read_sunos_user(struct pt_regs *regs, unsigned long offset,
				   struct task_struct *tsk, long *addr)
{
	struct pt_regs *cregs = tsk->tss.kregs;
	struct thread_struct *t = &tsk->tss;
	int v;
	
	if(offset >= 1024)
		offset -= 1024; /* whee... */
	if(offset & ((sizeof(unsigned long) - 1))) {
		pt_error_return(regs, EIO);
		return;
	}
	if(offset >= 16 && offset < 784) {
		offset -= 16; offset >>= 2;
		pt_os_succ_return(regs, *(((unsigned long *)(&t->reg_window[0]))+offset), addr);
		return;
	}
	if(offset >= 784 && offset < 832) {
		offset -= 784; offset >>= 2;
		pt_os_succ_return(regs, *(((unsigned long *)(&t->rwbuf_stkptrs[0]))+offset), addr);
		return;
	}
	switch(offset) {
	case 0:
		v = t->ksp;
		break;
	case 4:
		v = t->kpc;
		break;
	case 8:
		v = t->kpsr;
		break;
	case 12:
		v = t->uwinmask;
		break;
	case 832:
		v = t->w_saved;
		break;
	case 896:
		v = cregs->u_regs[UREG_I0];
		break;
	case 900:
		v = cregs->u_regs[UREG_I1];
		break;
	case 904:
		v = cregs->u_regs[UREG_I2];
		break;
	case 908:
		v = cregs->u_regs[UREG_I3];
		break;
	case 912:
		v = cregs->u_regs[UREG_I4];
		break;
	case 916:
		v = cregs->u_regs[UREG_I5];
		break;
	case 920:
		v = cregs->u_regs[UREG_I6];
		break;
	case 924:
		if(tsk->tss.flags & MAGIC_CONSTANT)
			v = cregs->u_regs[UREG_G1];
		else
			v = 0;
		break;
	case 940:
		v = cregs->u_regs[UREG_I0];
		break;
	case 944:
		v = cregs->u_regs[UREG_I1];
		break;

	case 948:
		/* Isn't binary compatibility _fun_??? */
		if(cregs->psr & PSR_C)
			v = cregs->u_regs[UREG_I0] << 24;
		else
			v = 0;
		break;

		/* Rest of them are completely unsupported. */
	default:
		printk("%s [%d]: Wants to read user offset %ld\n",
		       current->comm, current->pid, offset);
		pt_error_return(regs, EIO);
		return;
	}
	if (current->personality & PER_BSD)
		pt_succ_return (regs, v);
	else
		pt_succ_return_linux (regs, v, addr);
	return;
}

static inline void write_sunos_user(struct pt_regs *regs, unsigned long offset,
				    struct task_struct *tsk)
{
	struct pt_regs *cregs = tsk->tss.kregs;
	struct thread_struct *t = &tsk->tss;
	unsigned long value = regs->u_regs[UREG_I3];

	if(offset >= 1024)
		offset -= 1024; /* whee... */
	if(offset & ((sizeof(unsigned long) - 1)))
		goto failure;
	if(offset >= 16 && offset < 784) {
		offset -= 16; offset >>= 2;
		*(((unsigned long *)(&t->reg_window[0]))+offset) = value;
		goto success;
	}
	if(offset >= 784 && offset < 832) {
		offset -= 784; offset >>= 2;
		*(((unsigned long *)(&t->rwbuf_stkptrs[0]))+offset) = value;
		goto success;
	}
	switch(offset) {
	case 896:
		cregs->u_regs[UREG_I0] = value;
		break;
	case 900:
		cregs->u_regs[UREG_I1] = value;
		break;
	case 904:
		cregs->u_regs[UREG_I2] = value;
		break;
	case 908:
		cregs->u_regs[UREG_I3] = value;
		break;
	case 912:
		cregs->u_regs[UREG_I4] = value;
		break;
	case 916:
		cregs->u_regs[UREG_I5] = value;
		break;
	case 920:
		cregs->u_regs[UREG_I6] = value;
		break;
	case 924:
		cregs->u_regs[UREG_I7] = value;
		break;
	case 940:
		cregs->u_regs[UREG_I0] = value;
		break;
	case 944:
		cregs->u_regs[UREG_I1] = value;
		break;

		/* Rest of them are completely unsupported or "no-touch". */
	default:
		printk("%s [%d]: Wants to write user offset %ld\n",
		       current->comm, current->pid, offset);
		goto failure;
	}
success:
	pt_succ_return(regs, 0);
	return;
failure:
	pt_error_return(regs, EIO);
	return;
}

/* #define ALLOW_INIT_TRACING */
/* #define DEBUG_PTRACE */

#ifdef DEBUG_PTRACE
char *pt_rq [] = {
"TRACEME",
"PEEKTEXT",
"PEEKDATA",
"PEEKUSR",
"POKETEXT",
"POKEDATA",
"POKEUSR",
"CONT",
"KILL",
"SINGLESTEP",
"SUNATTACH",
"SUNDETACH",
"GETREGS",
"SETREGS",
"GETFPREGS",
"SETFPREGS",
"READDATA",
"WRITEDATA",
"READTEXT",
"WRITETEXT",
"GETFPAREGS",
"SETFPAREGS",
""
};
#endif

asmlinkage void do_ptrace(struct pt_regs *regs)
{
	unsigned long request = regs->u_regs[UREG_I0];
	unsigned long pid = regs->u_regs[UREG_I1];
	unsigned long addr = regs->u_regs[UREG_I2];
	unsigned long data = regs->u_regs[UREG_I3];
	unsigned long addr2 = regs->u_regs[UREG_I4];
	struct task_struct *child;

	lock_kernel();
#ifdef DEBUG_PTRACE
	{
		char *s;

		if ((request > 0) && (request < 21))
			s = pt_rq [request];
		else
			s = "unknown";

		if (request == PTRACE_POKEDATA && data == 0x91d02001){
			printk ("do_ptrace: breakpoint pid=%d, addr=%08lx addr2=%08lx\n",
				pid, addr, addr2);
		} else 
			printk("do_ptrace: rq=%s(%d) pid=%d addr=%08lx data=%08lx addr2=%08lx\n",
			       s, (int) request, (int) pid, addr, data, addr2);
	}
#endif
	if(request == PTRACE_TRACEME) {
		/* are we already being traced? */
		if (current->flags & PF_PTRACED) {
			pt_error_return(regs, EPERM);
			goto out;
		}
		/* set the ptrace bit in the process flags. */
		current->flags |= PF_PTRACED;
		pt_succ_return(regs, 0);
		goto out;
	}
#ifndef ALLOW_INIT_TRACING
	if(pid == 1) {
		/* Can't dork with init. */
		pt_error_return(regs, EPERM);
		goto out;
	}
#endif
	if(!(child = find_task_by_pid(pid))) {
		pt_error_return(regs, ESRCH);
		goto out;
	}

	if (((current->personality & PER_BSD) && (request == PTRACE_SUNATTACH))
	    || (!(current->personality & PER_BSD) && (request == PTRACE_ATTACH))) {
		if(child == current) {
			/* Try this under SunOS/Solaris, bwa haha
			 * You'll never be able to kill the process. ;-)
			 */
			pt_error_return(regs, EPERM);
			goto out;
		}
		if((!child->dumpable ||
		    (current->uid != child->euid) ||
		    (current->uid != child->uid) ||
		    (current->gid != child->egid) ||
		    (current->gid != child->gid)) && 
		   !capable(CAP_SYS_PTRACE)) {
			pt_error_return(regs, EPERM);
			goto out;
		}
		/* the same process cannot be attached many times */
		if (child->flags & PF_PTRACED) {
			pt_error_return(regs, EPERM);
			goto out;
		}
		child->flags |= PF_PTRACED;
		if(child->p_pptr != current) {
			unsigned long flags;
			write_lock_irqsave(&tasklist_lock, flags);
			REMOVE_LINKS(child);
			child->p_pptr = current;
			SET_LINKS(child);
			write_unlock_irqrestore(&tasklist_lock, flags);
		}
		send_sig(SIGSTOP, child, 1);
		pt_succ_return(regs, 0);
		goto out;
	}
	if (!(child->flags & PF_PTRACED)
	    && ((current->personality & PER_BSD) && (request != PTRACE_SUNATTACH))
	    && (!(current->personality & PER_BSD) && (request != PTRACE_ATTACH))) {
		pt_error_return(regs, ESRCH);
		goto out;
	}
	if(child->state != TASK_STOPPED) {
		if(request != PTRACE_KILL) {
			pt_error_return(regs, ESRCH);
			goto out;
		}
	}
	if(child->p_pptr != current) {
		pt_error_return(regs, ESRCH);
		goto out;
	}
	switch(request) {
	case PTRACE_PEEKTEXT: /* read word at location addr. */ 
	case PTRACE_PEEKDATA: {
		unsigned long tmp;
		int res;

		/* XXX Find out what is really going on. */
		flush_cache_all();

		/* Non-word alignment _not_ allowed on Sparc. */
		if(addr & (sizeof(unsigned long) - 1)) {
			pt_error_return(regs, EINVAL);
			goto out;
		}
		down(&child->mm->mmap_sem);
		res = read_long(child, addr, &tmp);
		up(&child->mm->mmap_sem);
		if (res < 0) {
			pt_error_return(regs, -res);
			goto out;
		}
		pt_os_succ_return(regs, tmp, (long *) data);
		goto out;
	}

	case PTRACE_PEEKUSR:
		read_sunos_user(regs, addr, child, (long *) data);
		goto out;

	case PTRACE_POKEUSR:
		write_sunos_user(regs, addr, child);
		goto out;

	case PTRACE_POKETEXT: /* write the word at location addr. */
	case PTRACE_POKEDATA: {
		struct vm_area_struct *vma;
		int res;

		/* Non-word alignment _not_ allowed on Sparc. */
		if(addr & (sizeof(unsigned long) - 1)) {
			pt_error_return(regs, EINVAL);
			goto out;
		}
		down(&child->mm->mmap_sem);
		vma = find_extend_vma(child, addr);
		res = write_long(child, addr, data);
		up(&child->mm->mmap_sem);
		if(res < 0)
			pt_error_return(regs, -res);
		else
			pt_succ_return(regs, res);
		goto out;
	}

	case PTRACE_GETREGS: {
		struct pt_regs *pregs = (struct pt_regs *) addr;
		struct pt_regs *cregs = child->tss.kregs;
		int rval;

		rval = verify_area(VERIFY_WRITE, pregs, sizeof(struct pt_regs));
		if(rval) {
			pt_error_return(regs, -rval);
			goto out;
		}
		__put_user(cregs->psr, (&pregs->psr));
		__put_user(cregs->pc, (&pregs->pc));
		__put_user(cregs->npc, (&pregs->npc));
		__put_user(cregs->y, (&pregs->y));
		for(rval = 1; rval < 16; rval++)
			__put_user(cregs->u_regs[rval], (&pregs->u_regs[rval - 1]));
		pt_succ_return(regs, 0);
#ifdef DEBUG_PTRACE
		printk ("PC=%x nPC=%x o7=%x\n", cregs->pc, cregs->npc, cregs->u_regs [15]);
#endif
		goto out;
	}

	case PTRACE_SETREGS: {
		struct pt_regs *pregs = (struct pt_regs *) addr;
		struct pt_regs *cregs = child->tss.kregs;
		unsigned long psr, pc, npc, y;
		int i;

		/* Must be careful, tracing process can only set certain
		 * bits in the psr.
		 */
		i = verify_area(VERIFY_READ, pregs, sizeof(struct pt_regs));
		if(i) {
			pt_error_return(regs, -i);
			goto out;
		}
		__get_user(psr, (&pregs->psr));
		__get_user(pc, (&pregs->pc));
		__get_user(npc, (&pregs->npc));
		__get_user(y, (&pregs->y));
		psr &= PSR_ICC;
		cregs->psr &= ~PSR_ICC;
		cregs->psr |= psr;
		if(!((pc | npc) & 3)) {
			cregs->pc = pc;
			cregs->npc =npc;
		}
		cregs->y = y;
		for(i = 1; i < 16; i++)
			__get_user(cregs->u_regs[i], (&pregs->u_regs[i-1]));
		pt_succ_return(regs, 0);
		goto out;
	}

	case PTRACE_GETFPREGS: {
		struct fps {
			unsigned long regs[32];
			unsigned long fsr;
			unsigned long flags;
			unsigned long extra;
			unsigned long fpqd;
			struct fq {
				unsigned long *insnaddr;
				unsigned long insn;
			} fpq[16];
		} *fps = (struct fps *) addr;
		int i;

		i = verify_area(VERIFY_WRITE, fps, sizeof(struct fps));
		if(i) {
			pt_error_return(regs, -i);
			goto out;
		}
		for(i = 0; i < 32; i++)
			__put_user(child->tss.float_regs[i], (&fps->regs[i]));
		__put_user(child->tss.fsr, (&fps->fsr));
		__put_user(child->tss.fpqdepth, (&fps->fpqd));
		__put_user(0, (&fps->flags));
		__put_user(0, (&fps->extra));
		for(i = 0; i < 16; i++) {
			__put_user(child->tss.fpqueue[i].insn_addr,
				   (&fps->fpq[i].insnaddr));
			__put_user(child->tss.fpqueue[i].insn, (&fps->fpq[i].insn));
		}
		pt_succ_return(regs, 0);
		goto out;
	}

	case PTRACE_SETFPREGS: {
		struct fps {
			unsigned long regs[32];
			unsigned long fsr;
			unsigned long flags;
			unsigned long extra;
			unsigned long fpqd;
			struct fq {
				unsigned long *insnaddr;
				unsigned long insn;
			} fpq[16];
		} *fps = (struct fps *) addr;
		int i;

		i = verify_area(VERIFY_READ, fps, sizeof(struct fps));
		if(i) {
			pt_error_return(regs, -i);
			goto out;
		}
		copy_from_user(&child->tss.float_regs[0], &fps->regs[0], (32 * sizeof(unsigned long)));
		__get_user(child->tss.fsr, (&fps->fsr));
		__get_user(child->tss.fpqdepth, (&fps->fpqd));
		for(i = 0; i < 16; i++) {
			__get_user(child->tss.fpqueue[i].insn_addr,
				   (&fps->fpq[i].insnaddr));
			__get_user(child->tss.fpqueue[i].insn, (&fps->fpq[i].insn));
		}
		pt_succ_return(regs, 0);
		goto out;
	}

	case PTRACE_READTEXT:
	case PTRACE_READDATA: {
		unsigned char *dest = (unsigned char *) addr2;
		unsigned long src = addr;
		unsigned char tmp;
		int res, len = data;

		res = verify_area(VERIFY_WRITE, dest, len);
		if(res) {
			pt_error_return(regs, -res);
			goto out;
		}
		while(len) {
			down(&child->mm->mmap_sem);
			res = read_byte(child, src, &tmp);
			up(&child->mm->mmap_sem);
			if(res < 0) {
				pt_error_return(regs, -res);
				goto out;
			}
			__put_user(tmp, dest);
			src++; dest++; len--;
		}
		pt_succ_return(regs, 0);
		goto out;
	}

	case PTRACE_WRITETEXT:
	case PTRACE_WRITEDATA: {
		unsigned char *src = (unsigned char *) addr2;
		unsigned long dest = addr;
		int res, len = data;

		res = verify_area(VERIFY_READ, src, len);
		if(res) {
			pt_error_return(regs, -res);
			goto out;
		}
		while(len) {
			unsigned long tmp;

			__get_user(tmp, src);
			down(&child->mm->mmap_sem);
			res = write_byte(child, dest, tmp);
			up(&child->mm->mmap_sem);
			if(res < 0) {
				pt_error_return(regs, -res);
				goto out;
			}
			src++; dest++; len--;
		}
		pt_succ_return(regs, 0);
		goto out;
	}

	case PTRACE_SYSCALL: /* continue and stop at (return from) syscall */
		addr = 1;

	case PTRACE_CONT: { /* restart after signal. */
		if ((unsigned long) data > _NSIG) {
			pt_error_return(regs, EIO);
			goto out;
		}
		if (addr != 1) {
			if (addr & 3) {
				pt_error_return(regs, EINVAL);
				goto out;
			}
#ifdef DEBUG_PTRACE
			printk ("Original: %08lx %08lx\n", child->tss.kregs->pc, child->tss.kregs->npc);
			printk ("Continuing with %08lx %08lx\n", addr, addr+4);
#endif
			child->tss.kregs->pc = addr;
			child->tss.kregs->npc = addr + 4;
		}

		if (request == PTRACE_SYSCALL)
			child->flags |= PF_TRACESYS;
		else
			child->flags &= ~PF_TRACESYS;

		child->exit_code = data;
#ifdef DEBUG_PTRACE
		printk("CONT: %s [%d]: set exit_code = %x %x %x\n", child->comm,
			child->pid, child->exit_code,
			child->tss.kregs->pc,
			child->tss.kregs->npc);
		       
#endif
		wake_up_process(child);
		pt_succ_return(regs, 0);
		goto out;
	}

/*
 * make the child exit.  Best I can do is send it a sigkill. 
 * perhaps it should be put in the status that it wants to 
 * exit.
 */
	case PTRACE_KILL: {
		if (child->state == TASK_ZOMBIE) {	/* already dead */
			pt_succ_return(regs, 0);
			goto out;
		}
		wake_up_process(child);
		child->exit_code = SIGKILL;
		pt_succ_return(regs, 0);
		goto out;
	}

	case PTRACE_SUNDETACH: { /* detach a process that was attached. */
		unsigned long flags;
		if ((unsigned long) data > _NSIG) {
			pt_error_return(regs, EIO);
			goto out;
		}
		child->flags &= ~(PF_PTRACED|PF_TRACESYS);
		wake_up_process(child);
		child->exit_code = data;
		write_lock_irqsave(&tasklist_lock, flags);
		REMOVE_LINKS(child);
		child->p_pptr = child->p_opptr;
		SET_LINKS(child);
		write_unlock_irqrestore(&tasklist_lock, flags);
		pt_succ_return(regs, 0);
		goto out;
	}

	/* PTRACE_DUMPCORE unsupported... */

	default:
		pt_error_return(regs, EIO);
		goto out;
	}
out:
	unlock_kernel();
}

asmlinkage void syscall_trace(void)
{
#ifdef DEBUG_PTRACE
	printk("%s [%d]: syscall_trace\n", current->comm, current->pid);
#endif
	if ((current->flags & (PF_PTRACED|PF_TRACESYS))
			!= (PF_PTRACED|PF_TRACESYS))
		return;
	current->exit_code = SIGTRAP;
	current->state = TASK_STOPPED;
	current->tss.flags ^= MAGIC_CONSTANT;
	notify_parent(current, SIGCHLD);
	schedule();
	/*
	 * this isn't the same as continuing with a signal, but it will do
	 * for normal use.  strace only continues with a signal if the
	 * stopping signal is not SIGTRAP.  -brl
	 */
#ifdef DEBUG_PTRACE
	printk("%s [%d]: syscall_trace exit= %x\n", current->comm,
		current->pid, current->exit_code);
#endif
	if (current->exit_code) {
		send_sig (current->exit_code, current, 1);
		current->exit_code = 0;
	}
}