aboutsummaryrefslogtreecommitdiff
path: root/arch/arm/kernel/ptrace.c
blob: 0dd3b79b15c3d90f0ad54f52d4240392fb51258e (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
/*
 *  linux/arch/arm/kernel/ptrace.c
 *
 *  By Ross Biro 1/23/92
 * edited by Linus Torvalds
 * ARM modifications Copyright (C) 2000 Russell King
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/elf.h>
#include <linux/smp.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/security.h>
#include <linux/init.h>
#include <linux/signal.h>
#include <linux/uaccess.h>
#include <linux/perf_event.h>
#include <linux/hw_breakpoint.h>
#include <linux/regset.h>
#include <linux/audit.h>
#include <linux/tracehook.h>
#include <linux/unistd.h>

#include <asm/pgtable.h>
#include <asm/traps.h>

#define CREATE_TRACE_POINTS
#include <trace/events/syscalls.h>

#define REG_PC	15
#define REG_PSR	16
/*
 * does not yet catch signals sent when the child dies.
 * in exit.c or in signal.c.
 */

#if 0
/*
 * Breakpoint SWI instruction: SWI &9F0001
 */
#define BREAKINST_ARM	0xef9f0001
#define BREAKINST_THUMB	0xdf00		/* fill this in later */
#else
/*
 * New breakpoints - use an undefined instruction.  The ARM architecture
 * reference manual guarantees that the following instruction space
 * will produce an undefined instruction exception on all CPUs:
 *
 *  ARM:   xxxx 0111 1111 xxxx xxxx xxxx 1111 xxxx
 *  Thumb: 1101 1110 xxxx xxxx
 */
#define BREAKINST_ARM	0xe7f001f0
#define BREAKINST_THUMB	0xde01
#endif

struct pt_regs_offset {
	const char *name;
	int offset;
};

#define REG_OFFSET_NAME(r) \
	{.name = #r, .offset = offsetof(struct pt_regs, ARM_##r)}
#define REG_OFFSET_END {.name = NULL, .offset = 0}

static const struct pt_regs_offset regoffset_table[] = {
	REG_OFFSET_NAME(r0),
	REG_OFFSET_NAME(r1),
	REG_OFFSET_NAME(r2),
	REG_OFFSET_NAME(r3),
	REG_OFFSET_NAME(r4),
	REG_OFFSET_NAME(r5),
	REG_OFFSET_NAME(r6),
	REG_OFFSET_NAME(r7),
	REG_OFFSET_NAME(r8),
	REG_OFFSET_NAME(r9),
	REG_OFFSET_NAME(r10),
	REG_OFFSET_NAME(fp),
	REG_OFFSET_NAME(ip),
	REG_OFFSET_NAME(sp),
	REG_OFFSET_NAME(lr),
	REG_OFFSET_NAME(pc),
	REG_OFFSET_NAME(cpsr),
	REG_OFFSET_NAME(ORIG_r0),
	REG_OFFSET_END,
};

/**
 * regs_query_register_offset() - query register offset from its name
 * @name:	the name of a register
 *
 * regs_query_register_offset() returns the offset of a register in struct
 * pt_regs from its name. If the name is invalid, this returns -EINVAL;
 */
int regs_query_register_offset(const char *name)
{
	const struct pt_regs_offset *roff;
	for (roff = regoffset_table; roff->name != NULL; roff++)
		if (!strcmp(roff->name, name))
			return roff->offset;
	return -EINVAL;
}

/**
 * regs_query_register_name() - query register name from its offset
 * @offset:	the offset of a register in struct pt_regs.
 *
 * regs_query_register_name() returns the name of a register from its
 * offset in struct pt_regs. If the @offset is invalid, this returns NULL;
 */
const char *regs_query_register_name(unsigned int offset)
{
	const struct pt_regs_offset *roff;
	for (roff = regoffset_table; roff->name != NULL; roff++)
		if (roff->offset == offset)
			return roff->name;
	return NULL;
}

/**
 * regs_within_kernel_stack() - check the address in the stack
 * @regs:      pt_regs which contains kernel stack pointer.
 * @addr:      address which is checked.
 *
 * regs_within_kernel_stack() checks @addr is within the kernel stack page(s).
 * If @addr is within the kernel stack, it returns true. If not, returns false.
 */
bool regs_within_kernel_stack(struct pt_regs *regs, unsigned long addr)
{
	return ((addr & ~(THREAD_SIZE - 1))  ==
		(kernel_stack_pointer(regs) & ~(THREAD_SIZE - 1)));
}

/**
 * regs_get_kernel_stack_nth() - get Nth entry of the stack
 * @regs:	pt_regs which contains kernel stack pointer.
 * @n:		stack entry number.
 *
 * regs_get_kernel_stack_nth() returns @n th entry of the kernel stack which
 * is specified by @regs. If the @n th entry is NOT in the kernel stack,
 * this returns 0.
 */
unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs, unsigned int n)
{
	unsigned long *addr = (unsigned long *)kernel_stack_pointer(regs);
	addr += n;
	if (regs_within_kernel_stack(regs, (unsigned long)addr))
		return *addr;
	else
		return 0;
}

/*
 * this routine will get a word off of the processes privileged stack.
 * the offset is how far from the base addr as stored in the THREAD.
 * this routine assumes that all the privileged stacks are in our
 * data space.
 */
static inline long get_user_reg(struct task_struct *task, int offset)
{
	return task_pt_regs(task)->uregs[offset];
}

/*
 * this routine will put a word on the processes privileged stack.
 * the offset is how far from the base addr as stored in the THREAD.
 * this routine assumes that all the privileged stacks are in our
 * data space.
 */
static inline int
put_user_reg(struct task_struct *task, int offset, long data)
{
	struct pt_regs newregs, *regs = task_pt_regs(task);
	int ret = -EINVAL;

	newregs = *regs;
	newregs.uregs[offset] = data;

	if (valid_user_regs(&newregs)) {
		regs->uregs[offset] = data;
		ret = 0;
	}

	return ret;
}

/*
 * Called by kernel/ptrace.c when detaching..
 */
void ptrace_disable(struct task_struct *child)
{
	/* Nothing to do. */
}

/*
 * Handle hitting a breakpoint.
 */
void ptrace_break(struct task_struct *tsk, struct pt_regs *regs)
{
	siginfo_t info;

	info.si_signo = SIGTRAP;
	info.si_errno = 0;
	info.si_code  = TRAP_BRKPT;
	info.si_addr  = (void __user *)instruction_pointer(regs);

	force_sig_info(SIGTRAP, &info, tsk);
}

static int break_trap(struct pt_regs *regs, unsigned int instr)
{
	ptrace_break(current, regs);
	return 0;
}

static struct undef_hook arm_break_hook = {
	.instr_mask	= 0x0fffffff,
	.instr_val	= 0x07f001f0,
	.cpsr_mask	= PSR_T_BIT,
	.cpsr_val	= 0,
	.fn		= break_trap,
};

static struct undef_hook thumb_break_hook = {
	.instr_mask	= 0xffff,
	.instr_val	= 0xde01,
	.cpsr_mask	= PSR_T_BIT,
	.cpsr_val	= PSR_T_BIT,
	.fn		= break_trap,
};

static struct undef_hook thumb2_break_hook = {
	.instr_mask	= 0xffffffff,
	.instr_val	= 0xf7f0a000,
	.cpsr_mask	= PSR_T_BIT,
	.cpsr_val	= PSR_T_BIT,
	.fn		= break_trap,
};

static int __init ptrace_break_init(void)
{
	register_undef_hook(&arm_break_hook);
	register_undef_hook(&thumb_break_hook);
	register_undef_hook(&thumb2_break_hook);
	return 0;
}

core_initcall(ptrace_break_init);

/*
 * Read the word at offset "off" into the "struct user".  We
 * actually access the pt_regs stored on the kernel stack.
 */
static int ptrace_read_user(struct task_struct *tsk, unsigned long off,
			    unsigned long __user *ret)
{
	unsigned long tmp;

	if (off & 3)
		return -EIO;

	tmp = 0;
	if (off == PT_TEXT_ADDR)
		tmp = tsk->mm->start_code;
	else if (off == PT_DATA_ADDR)
		tmp = tsk->mm->start_data;
	else if (off == PT_TEXT_END_ADDR)
		tmp = tsk->mm->end_code;
	else if (off < sizeof(struct pt_regs))
		tmp = get_user_reg(tsk, off >> 2);
	else if (off >= sizeof(struct user))
		return -EIO;

	return put_user(tmp, ret);
}

/*
 * Write the word at offset "off" into "struct user".  We
 * actually access the pt_regs stored on the kernel stack.
 */
static int ptrace_write_user(struct task_struct *tsk, unsigned long off,
			     unsigned long val)
{
	if (off & 3 || off >= sizeof(struct user))
		return -EIO;

	if (off >= sizeof(struct pt_regs))
		return 0;

	return put_user_reg(tsk, off >> 2, val);
}

#ifdef CONFIG_IWMMXT

/*
 * Get the child iWMMXt state.
 */
static int ptrace_getwmmxregs(struct task_struct *tsk, void __user *ufp)
{
	struct thread_info *thread = task_thread_info(tsk);

	if (!test_ti_thread_flag(thread, TIF_USING_IWMMXT))
		return -ENODATA;
	iwmmxt_task_disable(thread);  /* force it to ram */
	return copy_to_user(ufp, &thread->fpstate.iwmmxt, IWMMXT_SIZE)
		? -EFAULT : 0;
}

/*
 * Set the child iWMMXt state.
 */
static int ptrace_setwmmxregs(struct task_struct *tsk, void __user *ufp)
{
	struct thread_info *thread = task_thread_info(tsk);

	if (!test_ti_thread_flag(thread, TIF_USING_IWMMXT))
		return -EACCES;
	iwmmxt_task_release(thread);  /* force a reload */
	return copy_from_user(&thread->fpstate.iwmmxt, ufp, IWMMXT_SIZE)
		? -EFAULT : 0;
}

#endif

#ifdef CONFIG_CRUNCH
/*
 * Get the child Crunch state.
 */
static int ptrace_getcrunchregs(struct task_struct *tsk, void __user *ufp)
{
	struct thread_info *thread = task_thread_info(tsk);

	crunch_task_disable(thread);  /* force it to ram */
	return copy_to_user(ufp, &thread->crunchstate, CRUNCH_SIZE)
		? -EFAULT : 0;
}

/*
 * Set the child Crunch state.
 */
static int ptrace_setcrunchregs(struct task_struct *tsk, void __user *ufp)
{
	struct thread_info *thread = task_thread_info(tsk);

	crunch_task_release(thread);  /* force a reload */
	return copy_from_user(&thread->crunchstate, ufp, CRUNCH_SIZE)
		? -EFAULT : 0;
}
#endif

#ifdef CONFIG_HAVE_HW_BREAKPOINT
/*
 * Convert a virtual register number into an index for a thread_info
 * breakpoint array. Breakpoints are identified using positive numbers
 * whilst watchpoints are negative. The registers are laid out as pairs
 * of (address, control), each pair mapping to a unique hw_breakpoint struct.
 * Register 0 is reserved for describing resource information.
 */
static int ptrace_hbp_num_to_idx(long num)
{
	if (num < 0)
		num = (ARM_MAX_BRP << 1) - num;
	return (num - 1) >> 1;
}

/*
 * Returns the virtual register number for the address of the
 * breakpoint at index idx.
 */
static long ptrace_hbp_idx_to_num(int idx)
{
	long mid = ARM_MAX_BRP << 1;
	long num = (idx << 1) + 1;
	return num > mid ? mid - num : num;
}

/*
 * Handle hitting a HW-breakpoint.
 */
static void ptrace_hbptriggered(struct perf_event *bp,
				     struct perf_sample_data *data,
				     struct pt_regs *regs)
{
	struct arch_hw_breakpoint *bkpt = counter_arch_bp(bp);
	long num;
	int i;
	siginfo_t info;

	for (i = 0; i < ARM_MAX_HBP_SLOTS; ++i)
		if (current->thread.debug.hbp[i] == bp)
			break;

	num = (i == ARM_MAX_HBP_SLOTS) ? 0 : ptrace_hbp_idx_to_num(i);

	info.si_signo	= SIGTRAP;
	info.si_errno	= (int)num;
	info.si_code	= TRAP_HWBKPT;
	info.si_addr	= (void __user *)(bkpt->trigger);

	force_sig_info(SIGTRAP, &info, current);
}

/*
 * Set ptrace breakpoint pointers to zero for this task.
 * This is required in order to prevent child processes from unregistering
 * breakpoints held by their parent.
 */
void clear_ptrace_hw_breakpoint(struct task_struct *tsk)
{
	memset(tsk->thread.debug.hbp, 0, sizeof(tsk->thread.debug.hbp));
}

/*
 * Unregister breakpoints from this task and reset the pointers in
 * the thread_struct.
 */
void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
{
	int i;
	struct thread_struct *t = &tsk->thread;

	for (i = 0; i < ARM_MAX_HBP_SLOTS; i++) {
		if (t->debug.hbp[i]) {
			unregister_hw_breakpoint(t->debug.hbp[i]);
			t->debug.hbp[i] = NULL;
		}
	}
}

static u32 ptrace_get_hbp_resource_info(void)
{
	u8 num_brps, num_wrps, debug_arch, wp_len;
	u32 reg = 0;

	num_brps	= hw_breakpoint_slots(TYPE_INST);
	num_wrps	= hw_breakpoint_slots(TYPE_DATA);
	debug_arch	= arch_get_debug_arch();
	wp_len		= arch_get_max_wp_len();

	reg		|= debug_arch;
	reg		<<= 8;
	reg		|= wp_len;
	reg		<<= 8;
	reg		|= num_wrps;
	reg		<<= 8;
	reg		|= num_brps;

	return reg;
}

static struct perf_event *ptrace_hbp_create(struct task_struct *tsk, int type)
{
	struct perf_event_attr attr;

	ptrace_breakpoint_init(&attr);

	/* Initialise fields to sane defaults. */
	attr.bp_addr	= 0;
	attr.bp_len	= HW_BREAKPOINT_LEN_4;
	attr.bp_type	= type;
	attr.disabled	= 1;

	return register_user_hw_breakpoint(&attr, ptrace_hbptriggered, NULL,
					   tsk);
}

static int ptrace_gethbpregs(struct task_struct *tsk, long num,
			     unsigned long  __user *data)
{
	u32 reg;
	int idx, ret = 0;
	struct perf_event *bp;
	struct arch_hw_breakpoint_ctrl arch_ctrl;

	if (num == 0) {
		reg = ptrace_get_hbp_resource_info();
	} else {
		idx = ptrace_hbp_num_to_idx(num);
		if (idx < 0 || idx >= ARM_MAX_HBP_SLOTS) {
			ret = -EINVAL;
			goto out;
		}

		bp = tsk->thread.debug.hbp[idx];
		if (!bp) {
			reg = 0;
			goto put;
		}

		arch_ctrl = counter_arch_bp(bp)->ctrl;

		/*
		 * Fix up the len because we may have adjusted it
		 * to compensate for an unaligned address.
		 */
		while (!(arch_ctrl.len & 0x1))
			arch_ctrl.len >>= 1;

		if (num & 0x1)
			reg = bp->attr.bp_addr;
		else
			reg = encode_ctrl_reg(arch_ctrl);
	}

put:
	if (put_user(reg, data))
		ret = -EFAULT;

out:
	return ret;
}

static int ptrace_sethbpregs(struct task_struct *tsk, long num,
			     unsigned long __user *data)
{
	int idx, gen_len, gen_type, implied_type, ret = 0;
	u32 user_val;
	struct perf_event *bp;
	struct arch_hw_breakpoint_ctrl ctrl;
	struct perf_event_attr attr;

	if (num == 0)
		goto out;
	else if (num < 0)
		implied_type = HW_BREAKPOINT_RW;
	else
		implied_type = HW_BREAKPOINT_X;

	idx = ptrace_hbp_num_to_idx(num);
	if (idx < 0 || idx >= ARM_MAX_HBP_SLOTS) {
		ret = -EINVAL;
		goto out;
	}

	if (get_user(user_val, data)) {
		ret = -EFAULT;
		goto out;
	}

	bp = tsk->thread.debug.hbp[idx];
	if (!bp) {
		bp = ptrace_hbp_create(tsk, implied_type);
		if (IS_ERR(bp)) {
			ret = PTR_ERR(bp);
			goto out;
		}
		tsk->thread.debug.hbp[idx] = bp;
	}

	attr = bp->attr;

	if (num & 0x1) {
		/* Address */
		attr.bp_addr	= user_val;
	} else {
		/* Control */
		decode_ctrl_reg(user_val, &ctrl);
		ret = arch_bp_generic_fields(ctrl, &gen_len, &gen_type);
		if (ret)
			goto out;

		if ((gen_type & implied_type) != gen_type) {
			ret = -EINVAL;
			goto out;
		}

		attr.bp_len	= gen_len;
		attr.bp_type	= gen_type;
		attr.disabled	= !ctrl.enabled;
	}

	ret = modify_user_hw_breakpoint(bp, &attr);
out:
	return ret;
}
#endif

/* regset get/set implementations */

static int gpr_get(struct task_struct *target,
		   const struct user_regset *regset,
		   unsigned int pos, unsigned int count,
		   void *kbuf, void __user *ubuf)
{
	struct pt_regs *regs = task_pt_regs(target);

	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
				   regs,
				   0, sizeof(*regs));
}

static int gpr_set(struct task_struct *target,
		   const struct user_regset *regset,
		   unsigned int pos, unsigned int count,
		   const void *kbuf, const void __user *ubuf)
{
	int ret;
	struct pt_regs newregs;

	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
				 &newregs,
				 0, sizeof(newregs));
	if (ret)
		return ret;

	if (!valid_user_regs(&newregs))
		return -EINVAL;

	*task_pt_regs(target) = newregs;
	return 0;
}

static int fpa_get(struct task_struct *target,
		   const struct user_regset *regset,
		   unsigned int pos, unsigned int count,
		   void *kbuf, void __user *ubuf)
{
	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
				   &task_thread_info(target)->fpstate,
				   0, sizeof(struct user_fp));
}

static int fpa_set(struct task_struct *target,
		   const struct user_regset *regset,
		   unsigned int pos, unsigned int count,
		   const void *kbuf, const void __user *ubuf)
{
	struct thread_info *thread = task_thread_info(target);

	thread->used_cp[1] = thread->used_cp[2] = 1;

	return user_regset_copyin(&pos, &count, &kbuf, &ubuf,
		&thread->fpstate,
		0, sizeof(struct user_fp));
}

#ifdef CONFIG_VFP
/*
 * VFP register get/set implementations.
 *
 * With respect to the kernel, struct user_fp is divided into three chunks:
 * 16 or 32 real VFP registers (d0-d15 or d0-31)
 *	These are transferred to/from the real registers in the task's
 *	vfp_hard_struct.  The number of registers depends on the kernel
 *	configuration.
 *
 * 16 or 0 fake VFP registers (d16-d31 or empty)
 *	i.e., the user_vfp structure has space for 32 registers even if
 *	the kernel doesn't have them all.
 *
 *	vfp_get() reads this chunk as zero where applicable
 *	vfp_set() ignores this chunk
 *
 * 1 word for the FPSCR
 *
 * The bounds-checking logic built into user_regset_copyout and friends
 * means that we can make a simple sequence of calls to map the relevant data
 * to/from the specified slice of the user regset structure.
 */
static int vfp_get(struct task_struct *target,
		   const struct user_regset *regset,
		   unsigned int pos, unsigned int count,
		   void *kbuf, void __user *ubuf)
{
	int ret;
	struct thread_info *thread = task_thread_info(target);
	struct vfp_hard_struct const *vfp = &thread->vfpstate.hard;
	const size_t user_fpregs_offset = offsetof(struct user_vfp, fpregs);
	const size_t user_fpscr_offset = offsetof(struct user_vfp, fpscr);

	vfp_sync_hwstate(thread);

	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
				  &vfp->fpregs,
				  user_fpregs_offset,
				  user_fpregs_offset + sizeof(vfp->fpregs));
	if (ret)
		return ret;

	ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
				       user_fpregs_offset + sizeof(vfp->fpregs),
				       user_fpscr_offset);
	if (ret)
		return ret;

	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
				   &vfp->fpscr,
				   user_fpscr_offset,
				   user_fpscr_offset + sizeof(vfp->fpscr));
}

/*
 * For vfp_set() a read-modify-write is done on the VFP registers,
 * in order to avoid writing back a half-modified set of registers on
 * failure.
 */
static int vfp_set(struct task_struct *target,
			  const struct user_regset *regset,
			  unsigned int pos, unsigned int count,
			  const void *kbuf, const void __user *ubuf)
{
	int ret;
	struct thread_info *thread = task_thread_info(target);
	struct vfp_hard_struct new_vfp;
	const size_t user_fpregs_offset = offsetof(struct user_vfp, fpregs);
	const size_t user_fpscr_offset = offsetof(struct user_vfp, fpscr);

	vfp_sync_hwstate(thread);
	new_vfp = thread->vfpstate.hard;

	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
				  &new_vfp.fpregs,
				  user_fpregs_offset,
				  user_fpregs_offset + sizeof(new_vfp.fpregs));
	if (ret)
		return ret;

	ret = user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf,
				user_fpregs_offset + sizeof(new_vfp.fpregs),
				user_fpscr_offset);
	if (ret)
		return ret;

	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
				 &new_vfp.fpscr,
				 user_fpscr_offset,
				 user_fpscr_offset + sizeof(new_vfp.fpscr));
	if (ret)
		return ret;

	vfp_flush_hwstate(thread);
	thread->vfpstate.hard = new_vfp;

	return 0;
}
#endif /* CONFIG_VFP */

enum arm_regset {
	REGSET_GPR,
	REGSET_FPR,
#ifdef CONFIG_VFP
	REGSET_VFP,
#endif
};

static const struct user_regset arm_regsets[] = {
	[REGSET_GPR] = {
		.core_note_type = NT_PRSTATUS,
		.n = ELF_NGREG,
		.size = sizeof(u32),
		.align = sizeof(u32),
		.get = gpr_get,
		.set = gpr_set
	},
	[REGSET_FPR] = {
		/*
		 * For the FPA regs in fpstate, the real fields are a mixture
		 * of sizes, so pretend that the registers are word-sized:
		 */
		.core_note_type = NT_PRFPREG,
		.n = sizeof(struct user_fp) / sizeof(u32),
		.size = sizeof(u32),
		.align = sizeof(u32),
		.get = fpa_get,
		.set = fpa_set
	},
#ifdef CONFIG_VFP
	[REGSET_VFP] = {
		/*
		 * Pretend that the VFP regs are word-sized, since the FPSCR is
		 * a single word dangling at the end of struct user_vfp:
		 */
		.core_note_type = NT_ARM_VFP,
		.n = ARM_VFPREGS_SIZE / sizeof(u32),
		.size = sizeof(u32),
		.align = sizeof(u32),
		.get = vfp_get,
		.set = vfp_set
	},
#endif /* CONFIG_VFP */
};

static const struct user_regset_view user_arm_view = {
	.name = "arm", .e_machine = ELF_ARCH, .ei_osabi = ELF_OSABI,
	.regsets = arm_regsets, .n = ARRAY_SIZE(arm_regsets)
};

const struct user_regset_view *task_user_regset_view(struct task_struct *task)
{
	return &user_arm_view;
}

long arch_ptrace(struct task_struct *child, long request,
		 unsigned long addr, unsigned long data)
{
	int ret;
	unsigned long __user *datap = (unsigned long __user *) data;

	switch (request) {
		case PTRACE_PEEKUSR:
			ret = ptrace_read_user(child, addr, datap);
			break;

		case PTRACE_POKEUSR:
			ret = ptrace_write_user(child, addr, data);
			break;

		case PTRACE_GETREGS:
			ret = copy_regset_to_user(child,
						  &user_arm_view, REGSET_GPR,
						  0, sizeof(struct pt_regs),
						  datap);
			break;

		case PTRACE_SETREGS:
			ret = copy_regset_from_user(child,
						    &user_arm_view, REGSET_GPR,
						    0, sizeof(struct pt_regs),
						    datap);
			break;

		case PTRACE_GETFPREGS:
			ret = copy_regset_to_user(child,
						  &user_arm_view, REGSET_FPR,
						  0, sizeof(union fp_state),
						  datap);
			break;

		case PTRACE_SETFPREGS:
			ret = copy_regset_from_user(child,
						    &user_arm_view, REGSET_FPR,
						    0, sizeof(union fp_state),
						    datap);
			break;

#ifdef CONFIG_IWMMXT
		case PTRACE_GETWMMXREGS:
			ret = ptrace_getwmmxregs(child, datap);
			break;

		case PTRACE_SETWMMXREGS:
			ret = ptrace_setwmmxregs(child, datap);
			break;
#endif

		case PTRACE_GET_THREAD_AREA:
			ret = put_user(task_thread_info(child)->tp_value[0],
				       datap);
			break;

		case PTRACE_SET_SYSCALL:
			task_thread_info(child)->syscall = data;
			ret = 0;
			break;

#ifdef CONFIG_CRUNCH
		case PTRACE_GETCRUNCHREGS:
			ret = ptrace_getcrunchregs(child, datap);
			break;

		case PTRACE_SETCRUNCHREGS:
			ret = ptrace_setcrunchregs(child, datap);
			break;
#endif

#ifdef CONFIG_VFP
		case PTRACE_GETVFPREGS:
			ret = copy_regset_to_user(child,
						  &user_arm_view, REGSET_VFP,
						  0, ARM_VFPREGS_SIZE,
						  datap);
			break;

		case PTRACE_SETVFPREGS:
			ret = copy_regset_from_user(child,
						    &user_arm_view, REGSET_VFP,
						    0, ARM_VFPREGS_SIZE,
						    datap);
			break;
#endif

#ifdef CONFIG_HAVE_HW_BREAKPOINT
		case PTRACE_GETHBPREGS:
			ret = ptrace_gethbpregs(child, addr,
						(unsigned long __user *)data);
			break;
		case PTRACE_SETHBPREGS:
			ret = ptrace_sethbpregs(child, addr,
						(unsigned long __user *)data);
			break;
#endif

		default:
			ret = ptrace_request(child, request, addr, data);
			break;
	}

	return ret;
}

enum ptrace_syscall_dir {
	PTRACE_SYSCALL_ENTER = 0,
	PTRACE_SYSCALL_EXIT,
};

static int tracehook_report_syscall(struct pt_regs *regs,
				    enum ptrace_syscall_dir dir)
{
	unsigned long ip;

	/*
	 * IP is used to denote syscall entry/exit:
	 * IP = 0 -> entry, =1 -> exit
	 */
	ip = regs->ARM_ip;
	regs->ARM_ip = dir;

	if (dir == PTRACE_SYSCALL_EXIT)
		tracehook_report_syscall_exit(regs, 0);
	else if (tracehook_report_syscall_entry(regs))
		current_thread_info()->syscall = -1;

	regs->ARM_ip = ip;
	return current_thread_info()->syscall;
}

asmlinkage int syscall_trace_enter(struct pt_regs *regs, int scno)
{
	current_thread_info()->syscall = scno;

	/* Do the secure computing check first; failures should be fast. */
	if (secure_computing(scno) == -1)
		return -1;

	if (test_thread_flag(TIF_SYSCALL_TRACE))
		scno = tracehook_report_syscall(regs, PTRACE_SYSCALL_ENTER);

	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
		trace_sys_enter(regs, scno);

	audit_syscall_entry(AUDIT_ARCH_ARM, scno, regs->ARM_r0, regs->ARM_r1,
			    regs->ARM_r2, regs->ARM_r3);

	return scno;
}

asmlinkage void syscall_trace_exit(struct pt_regs *regs)
{
	/*
	 * Audit the syscall before anything else, as a debugger may
	 * come in and change the current registers.
	 */
	audit_syscall_exit(regs);

	/*
	 * Note that we haven't updated the ->syscall field for the
	 * current thread. This isn't a problem because it will have
	 * been set on syscall entry and there hasn't been an opportunity
	 * for a PTRACE_SET_SYSCALL since then.
	 */
	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
		trace_sys_exit(regs, regs_return_value(regs));

	if (test_thread_flag(TIF_SYSCALL_TRACE))
		tracehook_report_syscall(regs, PTRACE_SYSCALL_EXIT);
}