summaryrefslogtreecommitdiff
path: root/arch/ia64/kernel/kprobes.c
blob: 1a7bab1c5d7c2d95db00c4f6f8924f0f900d5966 (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
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Kernel Probes (KProbes)
 *  arch/ia64/kernel/kprobes.c
 *
 * Copyright (C) IBM Corporation, 2002, 2004
 * Copyright (C) Intel Corporation, 2005
 *
 * 2005-Apr     Rusty Lynch <rusty.lynch@intel.com> and Anil S Keshavamurthy
 *              <anil.s.keshavamurthy@intel.com> adapted from i386
 */

#include <linux/kprobes.h>
#include <linux/ptrace.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/preempt.h>
#include <linux/extable.h>
#include <linux/kdebug.h>
#include <linux/pgtable.h>

#include <asm/sections.h>
#include <asm/exception.h>

DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);

struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};

enum instruction_type {A, I, M, F, B, L, X, u};
static enum instruction_type bundle_encoding[32][3] = {
  { M, I, I },				/* 00 */
  { M, I, I },				/* 01 */
  { M, I, I },				/* 02 */
  { M, I, I },				/* 03 */
  { M, L, X },				/* 04 */
  { M, L, X },				/* 05 */
  { u, u, u },  			/* 06 */
  { u, u, u },  			/* 07 */
  { M, M, I },				/* 08 */
  { M, M, I },				/* 09 */
  { M, M, I },				/* 0A */
  { M, M, I },				/* 0B */
  { M, F, I },				/* 0C */
  { M, F, I },				/* 0D */
  { M, M, F },				/* 0E */
  { M, M, F },				/* 0F */
  { M, I, B },				/* 10 */
  { M, I, B },				/* 11 */
  { M, B, B },				/* 12 */
  { M, B, B },				/* 13 */
  { u, u, u },  			/* 14 */
  { u, u, u },  			/* 15 */
  { B, B, B },				/* 16 */
  { B, B, B },				/* 17 */
  { M, M, B },				/* 18 */
  { M, M, B },				/* 19 */
  { u, u, u },  			/* 1A */
  { u, u, u },  			/* 1B */
  { M, F, B },				/* 1C */
  { M, F, B },				/* 1D */
  { u, u, u },  			/* 1E */
  { u, u, u },  			/* 1F */
};

/* Insert a long branch code */
static void __kprobes set_brl_inst(void *from, void *to)
{
	s64 rel = ((s64) to - (s64) from) >> 4;
	bundle_t *brl;
	brl = (bundle_t *) ((u64) from & ~0xf);
	brl->quad0.template = 0x05;	/* [MLX](stop) */
	brl->quad0.slot0 = NOP_M_INST;	/* nop.m 0x0 */
	brl->quad0.slot1_p0 = ((rel >> 20) & 0x7fffffffff) << 2;
	brl->quad1.slot1_p1 = (((rel >> 20) & 0x7fffffffff) << 2) >> (64 - 46);
	/* brl.cond.sptk.many.clr rel<<4 (qp=0) */
	brl->quad1.slot2 = BRL_INST(rel >> 59, rel & 0xfffff);
}

/*
 * In this function we check to see if the instruction
 * is IP relative instruction and update the kprobe
 * inst flag accordingly
 */
static void __kprobes update_kprobe_inst_flag(uint template, uint  slot,
					      uint major_opcode,
					      unsigned long kprobe_inst,
					      struct kprobe *p)
{
	p->ainsn.inst_flag = 0;
	p->ainsn.target_br_reg = 0;
	p->ainsn.slot = slot;

	/* Check for Break instruction
	 * Bits 37:40 Major opcode to be zero
	 * Bits 27:32 X6 to be zero
	 * Bits 32:35 X3 to be zero
	 */
	if ((!major_opcode) && (!((kprobe_inst >> 27) & 0x1FF)) ) {
		/* is a break instruction */
	 	p->ainsn.inst_flag |= INST_FLAG_BREAK_INST;
		return;
	}

	if (bundle_encoding[template][slot] == B) {
		switch (major_opcode) {
		  case INDIRECT_CALL_OPCODE:
	 		p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
			p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
			break;
		  case IP_RELATIVE_PREDICT_OPCODE:
		  case IP_RELATIVE_BRANCH_OPCODE:
			p->ainsn.inst_flag |= INST_FLAG_FIX_RELATIVE_IP_ADDR;
			break;
		  case IP_RELATIVE_CALL_OPCODE:
			p->ainsn.inst_flag |= INST_FLAG_FIX_RELATIVE_IP_ADDR;
			p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
			p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
			break;
		}
	} else if (bundle_encoding[template][slot] == X) {
		switch (major_opcode) {
		  case LONG_CALL_OPCODE:
			p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
			p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
		  break;
		}
	}
	return;
}

/*
 * In this function we check to see if the instruction
 * (qp) cmpx.crel.ctype p1,p2=r2,r3
 * on which we are inserting kprobe is cmp instruction
 * with ctype as unc.
 */
static uint __kprobes is_cmp_ctype_unc_inst(uint template, uint slot,
					    uint major_opcode,
					    unsigned long kprobe_inst)
{
	cmp_inst_t cmp_inst;
	uint ctype_unc = 0;

	if (!((bundle_encoding[template][slot] == I) ||
		(bundle_encoding[template][slot] == M)))
		goto out;

	if (!((major_opcode == 0xC) || (major_opcode == 0xD) ||
		(major_opcode == 0xE)))
		goto out;

	cmp_inst.l = kprobe_inst;
	if ((cmp_inst.f.x2 == 0) || (cmp_inst.f.x2 == 1)) {
		/* Integer compare - Register Register (A6 type)*/
		if ((cmp_inst.f.tb == 0) && (cmp_inst.f.ta == 0)
				&&(cmp_inst.f.c == 1))
			ctype_unc = 1;
	} else if ((cmp_inst.f.x2 == 2)||(cmp_inst.f.x2 == 3)) {
		/* Integer compare - Immediate Register (A8 type)*/
		if ((cmp_inst.f.ta == 0) &&(cmp_inst.f.c == 1))
			ctype_unc = 1;
	}
out:
	return ctype_unc;
}

/*
 * In this function we check to see if the instruction
 * on which we are inserting kprobe is supported.
 * Returns qp value if supported
 * Returns -EINVAL if unsupported
 */
static int __kprobes unsupported_inst(uint template, uint  slot,
				      uint major_opcode,
				      unsigned long kprobe_inst,
				      unsigned long addr)
{
	int qp;

	qp = kprobe_inst & 0x3f;
	if (is_cmp_ctype_unc_inst(template, slot, major_opcode, kprobe_inst)) {
		if (slot == 1 && qp)  {
			printk(KERN_WARNING "Kprobes on cmp unc "
					"instruction on slot 1 at <0x%lx> "
					"is not supported\n", addr);
			return -EINVAL;

		}
		qp = 0;
	}
	else if (bundle_encoding[template][slot] == I) {
		if (major_opcode == 0) {
			/*
			 * Check for Integer speculation instruction
			 * - Bit 33-35 to be equal to 0x1
			 */
			if (((kprobe_inst >> 33) & 0x7) == 1) {
				printk(KERN_WARNING
					"Kprobes on speculation inst at <0x%lx> not supported\n",
						addr);
				return -EINVAL;
			}
			/*
			 * IP relative mov instruction
			 *  - Bit 27-35 to be equal to 0x30
			 */
			if (((kprobe_inst >> 27) & 0x1FF) == 0x30) {
				printk(KERN_WARNING
					"Kprobes on \"mov r1=ip\" at <0x%lx> not supported\n",
						addr);
				return -EINVAL;

			}
		}
		else if ((major_opcode == 5) &&	!(kprobe_inst & (0xFUl << 33)) &&
				(kprobe_inst & (0x1UL << 12))) {
			/* test bit instructions, tbit,tnat,tf
			 * bit 33-36 to be equal to 0
			 * bit 12 to be equal to 1
			 */
			if (slot == 1 && qp) {
				printk(KERN_WARNING "Kprobes on test bit "
						"instruction on slot at <0x%lx> "
						"is not supported\n", addr);
				return -EINVAL;
			}
			qp = 0;
		}
	}
	else if (bundle_encoding[template][slot] == B) {
		if (major_opcode == 7) {
			/* IP-Relative Predict major code is 7 */
			printk(KERN_WARNING "Kprobes on IP-Relative"
					"Predict is not supported\n");
			return -EINVAL;
		}
		else if (major_opcode == 2) {
			/* Indirect Predict, major code is 2
			 * bit 27-32 to be equal to 10 or 11
			 */
			int x6=(kprobe_inst >> 27) & 0x3F;
			if ((x6 == 0x10) || (x6 == 0x11)) {
				printk(KERN_WARNING "Kprobes on "
					"Indirect Predict is not supported\n");
				return -EINVAL;
			}
		}
	}
	/* kernel does not use float instruction, here for safety kprobe
	 * will judge whether it is fcmp/flass/float approximation instruction
	 */
	else if (unlikely(bundle_encoding[template][slot] == F)) {
		if ((major_opcode == 4 || major_opcode == 5) &&
				(kprobe_inst  & (0x1 << 12))) {
			/* fcmp/fclass unc instruction */
			if (slot == 1 && qp) {
				printk(KERN_WARNING "Kprobes on fcmp/fclass "
					"instruction on slot at <0x%lx> "
					"is not supported\n", addr);
				return -EINVAL;

			}
			qp = 0;
		}
		if ((major_opcode == 0 || major_opcode == 1) &&
			(kprobe_inst & (0x1UL << 33))) {
			/* float Approximation instruction */
			if (slot == 1 && qp) {
				printk(KERN_WARNING "Kprobes on float Approx "
					"instr at <0x%lx> is not supported\n",
						addr);
				return -EINVAL;
			}
			qp = 0;
		}
	}
	return qp;
}

/*
 * In this function we override the bundle with
 * the break instruction at the given slot.
 */
static void __kprobes prepare_break_inst(uint template, uint  slot,
					 uint major_opcode,
					 unsigned long kprobe_inst,
					 struct kprobe *p,
					 int qp)
{
	unsigned long break_inst = BREAK_INST;
	bundle_t *bundle = &p->opcode.bundle;

	/*
	 * Copy the original kprobe_inst qualifying predicate(qp)
	 * to the break instruction
	 */
	break_inst |= qp;

	switch (slot) {
	  case 0:
		bundle->quad0.slot0 = break_inst;
		break;
	  case 1:
		bundle->quad0.slot1_p0 = break_inst;
		bundle->quad1.slot1_p1 = break_inst >> (64-46);
		break;
	  case 2:
		bundle->quad1.slot2 = break_inst;
		break;
	}

	/*
	 * Update the instruction flag, so that we can
	 * emulate the instruction properly after we
	 * single step on original instruction
	 */
	update_kprobe_inst_flag(template, slot, major_opcode, kprobe_inst, p);
}

static void __kprobes get_kprobe_inst(bundle_t *bundle, uint slot,
	       	unsigned long *kprobe_inst, uint *major_opcode)
{
	unsigned long kprobe_inst_p0, kprobe_inst_p1;
	unsigned int template;

	template = bundle->quad0.template;

	switch (slot) {
	  case 0:
		*major_opcode = (bundle->quad0.slot0 >> SLOT0_OPCODE_SHIFT);
		*kprobe_inst = bundle->quad0.slot0;
		  break;
	  case 1:
		*major_opcode = (bundle->quad1.slot1_p1 >> SLOT1_p1_OPCODE_SHIFT);
		kprobe_inst_p0 = bundle->quad0.slot1_p0;
		kprobe_inst_p1 = bundle->quad1.slot1_p1;
		*kprobe_inst = kprobe_inst_p0 | (kprobe_inst_p1 << (64-46));
		break;
	  case 2:
		*major_opcode = (bundle->quad1.slot2 >> SLOT2_OPCODE_SHIFT);
		*kprobe_inst = bundle->quad1.slot2;
		break;
	}
}

/* Returns non-zero if the addr is in the Interrupt Vector Table */
static int __kprobes in_ivt_functions(unsigned long addr)
{
	return (addr >= (unsigned long)__start_ivt_text
		&& addr < (unsigned long)__end_ivt_text);
}

static int __kprobes valid_kprobe_addr(int template, int slot,
				       unsigned long addr)
{
	if ((slot > 2) || ((bundle_encoding[template][1] == L) && slot > 1)) {
		printk(KERN_WARNING "Attempting to insert unaligned kprobe "
				"at 0x%lx\n", addr);
		return -EINVAL;
	}

	if (in_ivt_functions(addr)) {
		printk(KERN_WARNING "Kprobes can't be inserted inside "
				"IVT functions at 0x%lx\n", addr);
		return -EINVAL;
	}

	return 0;
}

static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
{
	unsigned int i;
	i = atomic_add_return(1, &kcb->prev_kprobe_index);
	kcb->prev_kprobe[i-1].kp = kprobe_running();
	kcb->prev_kprobe[i-1].status = kcb->kprobe_status;
}

static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
{
	unsigned int i;
	i = atomic_read(&kcb->prev_kprobe_index);
	__this_cpu_write(current_kprobe, kcb->prev_kprobe[i-1].kp);
	kcb->kprobe_status = kcb->prev_kprobe[i-1].status;
	atomic_sub(1, &kcb->prev_kprobe_index);
}

static void __kprobes set_current_kprobe(struct kprobe *p,
			struct kprobe_ctlblk *kcb)
{
	__this_cpu_write(current_kprobe, p);
}

void __kretprobe_trampoline(void)
{
}

int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
{
	regs->cr_iip = __kretprobe_trampoline_handler(regs, NULL);
	/*
	 * By returning a non-zero value, we are telling
	 * kprobe_handler() that we don't want the post_handler
	 * to run (and have re-enabled preemption)
	 */
	return 1;
}

void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
				      struct pt_regs *regs)
{
	ri->ret_addr = (kprobe_opcode_t *)regs->b0;
	ri->fp = NULL;

	/* Replace the return addr with trampoline addr */
	regs->b0 = (unsigned long)dereference_function_descriptor(__kretprobe_trampoline);
}

/* Check the instruction in the slot is break */
static int __kprobes __is_ia64_break_inst(bundle_t *bundle, uint slot)
{
	unsigned int major_opcode;
	unsigned int template = bundle->quad0.template;
	unsigned long kprobe_inst;

	/* Move to slot 2, if bundle is MLX type and kprobe slot is 1 */
	if (slot == 1 && bundle_encoding[template][1] == L)
		slot++;

	/* Get Kprobe probe instruction at given slot*/
	get_kprobe_inst(bundle, slot, &kprobe_inst, &major_opcode);

	/* For break instruction,
	 * Bits 37:40 Major opcode to be zero
	 * Bits 27:32 X6 to be zero
	 * Bits 32:35 X3 to be zero
	 */
	if (major_opcode || ((kprobe_inst >> 27) & 0x1FF)) {
		/* Not a break instruction */
		return 0;
	}

	/* Is a break instruction */
	return 1;
}

/*
 * In this function, we check whether the target bundle modifies IP or
 * it triggers an exception. If so, it cannot be boostable.
 */
static int __kprobes can_boost(bundle_t *bundle, uint slot,
			       unsigned long bundle_addr)
{
	unsigned int template = bundle->quad0.template;

	do {
		if (search_exception_tables(bundle_addr + slot) ||
		    __is_ia64_break_inst(bundle, slot))
			return 0;	/* exception may occur in this bundle*/
	} while ((++slot) < 3);
	template &= 0x1e;
	if (template >= 0x10 /* including B unit */ ||
	    template == 0x04 /* including X unit */ ||
	    template == 0x06) /* undefined */
		return 0;

	return 1;
}

/* Prepare long jump bundle and disables other boosters if need */
static void __kprobes prepare_booster(struct kprobe *p)
{
	unsigned long addr = (unsigned long)p->addr & ~0xFULL;
	unsigned int slot = (unsigned long)p->addr & 0xf;
	struct kprobe *other_kp;

	if (can_boost(&p->ainsn.insn[0].bundle, slot, addr)) {
		set_brl_inst(&p->ainsn.insn[1].bundle, (bundle_t *)addr + 1);
		p->ainsn.inst_flag |= INST_FLAG_BOOSTABLE;
	}

	/* disables boosters in previous slots */
	for (; addr < (unsigned long)p->addr; addr++) {
		other_kp = get_kprobe((void *)addr);
		if (other_kp)
			other_kp->ainsn.inst_flag &= ~INST_FLAG_BOOSTABLE;
	}
}

int __kprobes arch_prepare_kprobe(struct kprobe *p)
{
	unsigned long addr = (unsigned long) p->addr;
	unsigned long *kprobe_addr = (unsigned long *)(addr & ~0xFULL);
	unsigned long kprobe_inst=0;
	unsigned int slot = addr & 0xf, template, major_opcode = 0;
	bundle_t *bundle;
	int qp;

	bundle = &((kprobe_opcode_t *)kprobe_addr)->bundle;
	template = bundle->quad0.template;

	if(valid_kprobe_addr(template, slot, addr))
		return -EINVAL;

	/* Move to slot 2, if bundle is MLX type and kprobe slot is 1 */
	if (slot == 1 && bundle_encoding[template][1] == L)
		slot++;

	/* Get kprobe_inst and major_opcode from the bundle */
	get_kprobe_inst(bundle, slot, &kprobe_inst, &major_opcode);

	qp = unsupported_inst(template, slot, major_opcode, kprobe_inst, addr);
	if (qp < 0)
		return -EINVAL;

	p->ainsn.insn = get_insn_slot();
	if (!p->ainsn.insn)
		return -ENOMEM;
	memcpy(&p->opcode, kprobe_addr, sizeof(kprobe_opcode_t));
	memcpy(p->ainsn.insn, kprobe_addr, sizeof(kprobe_opcode_t));

	prepare_break_inst(template, slot, major_opcode, kprobe_inst, p, qp);

	prepare_booster(p);

	return 0;
}

void __kprobes arch_arm_kprobe(struct kprobe *p)
{
	unsigned long arm_addr;
	bundle_t *src, *dest;

	arm_addr = ((unsigned long)p->addr) & ~0xFUL;
	dest = &((kprobe_opcode_t *)arm_addr)->bundle;
	src = &p->opcode.bundle;

	flush_icache_range((unsigned long)p->ainsn.insn,
			   (unsigned long)p->ainsn.insn +
			   sizeof(kprobe_opcode_t) * MAX_INSN_SIZE);

	switch (p->ainsn.slot) {
		case 0:
			dest->quad0.slot0 = src->quad0.slot0;
			break;
		case 1:
			dest->quad1.slot1_p1 = src->quad1.slot1_p1;
			break;
		case 2:
			dest->quad1.slot2 = src->quad1.slot2;
			break;
	}
	flush_icache_range(arm_addr, arm_addr + sizeof(kprobe_opcode_t));
}

void __kprobes arch_disarm_kprobe(struct kprobe *p)
{
	unsigned long arm_addr;
	bundle_t *src, *dest;

	arm_addr = ((unsigned long)p->addr) & ~0xFUL;
	dest = &((kprobe_opcode_t *)arm_addr)->bundle;
	/* p->ainsn.insn contains the original unaltered kprobe_opcode_t */
	src = &p->ainsn.insn->bundle;
	switch (p->ainsn.slot) {
		case 0:
			dest->quad0.slot0 = src->quad0.slot0;
			break;
		case 1:
			dest->quad1.slot1_p1 = src->quad1.slot1_p1;
			break;
		case 2:
			dest->quad1.slot2 = src->quad1.slot2;
			break;
	}
	flush_icache_range(arm_addr, arm_addr + sizeof(kprobe_opcode_t));
}

void __kprobes arch_remove_kprobe(struct kprobe *p)
{
	if (p->ainsn.insn) {
		free_insn_slot(p->ainsn.insn,
			       p->ainsn.inst_flag & INST_FLAG_BOOSTABLE);
		p->ainsn.insn = NULL;
	}
}
/*
 * We are resuming execution after a single step fault, so the pt_regs
 * structure reflects the register state after we executed the instruction
 * located in the kprobe (p->ainsn.insn->bundle).  We still need to adjust
 * the ip to point back to the original stack address. To set the IP address
 * to original stack address, handle the case where we need to fixup the
 * relative IP address and/or fixup branch register.
 */
static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
{
	unsigned long bundle_addr = (unsigned long) (&p->ainsn.insn->bundle);
	unsigned long resume_addr = (unsigned long)p->addr & ~0xFULL;
	unsigned long template;
	int slot = ((unsigned long)p->addr & 0xf);

	template = p->ainsn.insn->bundle.quad0.template;

	if (slot == 1 && bundle_encoding[template][1] == L)
		slot = 2;

	if (p->ainsn.inst_flag & ~INST_FLAG_BOOSTABLE) {

		if (p->ainsn.inst_flag & INST_FLAG_FIX_RELATIVE_IP_ADDR) {
			/* Fix relative IP address */
			regs->cr_iip = (regs->cr_iip - bundle_addr) +
					resume_addr;
		}

		if (p->ainsn.inst_flag & INST_FLAG_FIX_BRANCH_REG) {
		/*
		 * Fix target branch register, software convention is
		 * to use either b0 or b6 or b7, so just checking
		 * only those registers
		 */
			switch (p->ainsn.target_br_reg) {
			case 0:
				if ((regs->b0 == bundle_addr) ||
					(regs->b0 == bundle_addr + 0x10)) {
					regs->b0 = (regs->b0 - bundle_addr) +
						resume_addr;
				}
				break;
			case 6:
				if ((regs->b6 == bundle_addr) ||
					(regs->b6 == bundle_addr + 0x10)) {
					regs->b6 = (regs->b6 - bundle_addr) +
						resume_addr;
				}
				break;
			case 7:
				if ((regs->b7 == bundle_addr) ||
					(regs->b7 == bundle_addr + 0x10)) {
					regs->b7 = (regs->b7 - bundle_addr) +
						resume_addr;
				}
				break;
			} /* end switch */
		}
		goto turn_ss_off;
	}

	if (slot == 2) {
		if (regs->cr_iip == bundle_addr + 0x10) {
			regs->cr_iip = resume_addr + 0x10;
		}
	} else {
		if (regs->cr_iip == bundle_addr) {
			regs->cr_iip = resume_addr;
		}
	}

turn_ss_off:
	/* Turn off Single Step bit */
	ia64_psr(regs)->ss = 0;
}

static void __kprobes prepare_ss(struct kprobe *p, struct pt_regs *regs)
{
	unsigned long bundle_addr = (unsigned long) &p->ainsn.insn->bundle;
	unsigned long slot = (unsigned long)p->addr & 0xf;

	/* single step inline if break instruction */
	if (p->ainsn.inst_flag == INST_FLAG_BREAK_INST)
		regs->cr_iip = (unsigned long)p->addr & ~0xFULL;
	else
		regs->cr_iip = bundle_addr & ~0xFULL;

	if (slot > 2)
		slot = 0;

	ia64_psr(regs)->ri = slot;

	/* turn on single stepping */
	ia64_psr(regs)->ss = 1;
}

static int __kprobes is_ia64_break_inst(struct pt_regs *regs)
{
	unsigned int slot = ia64_psr(regs)->ri;
	unsigned long *kprobe_addr = (unsigned long *)regs->cr_iip;
	bundle_t bundle;

	memcpy(&bundle, kprobe_addr, sizeof(bundle_t));

	return __is_ia64_break_inst(&bundle, slot);
}

static int __kprobes pre_kprobes_handler(struct die_args *args)
{
	struct kprobe *p;
	int ret = 0;
	struct pt_regs *regs = args->regs;
	kprobe_opcode_t *addr = (kprobe_opcode_t *)instruction_pointer(regs);
	struct kprobe_ctlblk *kcb;

	/*
	 * We don't want to be preempted for the entire
	 * duration of kprobe processing
	 */
	preempt_disable();
	kcb = get_kprobe_ctlblk();

	/* Handle recursion cases */
	if (kprobe_running()) {
		p = get_kprobe(addr);
		if (p) {
			if ((kcb->kprobe_status == KPROBE_HIT_SS) &&
	 		     (p->ainsn.inst_flag == INST_FLAG_BREAK_INST)) {
				ia64_psr(regs)->ss = 0;
				goto no_kprobe;
			}
			/* We have reentered the pre_kprobe_handler(), since
			 * another probe was hit while within the handler.
			 * We here save the original kprobes variables and
			 * just single step on the instruction of the new probe
			 * without calling any user handlers.
			 */
			save_previous_kprobe(kcb);
			set_current_kprobe(p, kcb);
			kprobes_inc_nmissed_count(p);
			prepare_ss(p, regs);
			kcb->kprobe_status = KPROBE_REENTER;
			return 1;
		} else if (!is_ia64_break_inst(regs)) {
			/* The breakpoint instruction was removed by
			 * another cpu right after we hit, no further
			 * handling of this interrupt is appropriate
			 */
			ret = 1;
			goto no_kprobe;
		} else {
			/* Not our break */
			goto no_kprobe;
		}
	}

	p = get_kprobe(addr);
	if (!p) {
		if (!is_ia64_break_inst(regs)) {
			/*
			 * The breakpoint instruction was removed right
			 * after we hit it.  Another cpu has removed
			 * either a probepoint or a debugger breakpoint
			 * at this address.  In either case, no further
			 * handling of this interrupt is appropriate.
			 */
			ret = 1;

		}

		/* Not one of our break, let kernel handle it */
		goto no_kprobe;
	}

	set_current_kprobe(p, kcb);
	kcb->kprobe_status = KPROBE_HIT_ACTIVE;

	if (p->pre_handler && p->pre_handler(p, regs)) {
		reset_current_kprobe();
		preempt_enable_no_resched();
		return 1;
	}

#if !defined(CONFIG_PREEMPTION)
	if (p->ainsn.inst_flag == INST_FLAG_BOOSTABLE && !p->post_handler) {
		/* Boost up -- we can execute copied instructions directly */
		ia64_psr(regs)->ri = p->ainsn.slot;
		regs->cr_iip = (unsigned long)&p->ainsn.insn->bundle & ~0xFULL;
		/* turn single stepping off */
		ia64_psr(regs)->ss = 0;

		reset_current_kprobe();
		preempt_enable_no_resched();
		return 1;
	}
#endif
	prepare_ss(p, regs);
	kcb->kprobe_status = KPROBE_HIT_SS;
	return 1;

no_kprobe:
	preempt_enable_no_resched();
	return ret;
}

static int __kprobes post_kprobes_handler(struct pt_regs *regs)
{
	struct kprobe *cur = kprobe_running();
	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();

	if (!cur)
		return 0;

	if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
		kcb->kprobe_status = KPROBE_HIT_SSDONE;
		cur->post_handler(cur, regs, 0);
	}

	resume_execution(cur, regs);

	/*Restore back the original saved kprobes variables and continue. */
	if (kcb->kprobe_status == KPROBE_REENTER) {
		restore_previous_kprobe(kcb);
		goto out;
	}
	reset_current_kprobe();

out:
	preempt_enable_no_resched();
	return 1;
}

int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
{
	struct kprobe *cur = kprobe_running();
	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();


	switch(kcb->kprobe_status) {
	case KPROBE_HIT_SS:
	case KPROBE_REENTER:
		/*
		 * We are here because the instruction being single
		 * stepped caused a page fault. We reset the current
		 * kprobe and the instruction pointer points back to
		 * the probe address and allow the page fault handler
		 * to continue as a normal page fault.
		 */
		regs->cr_iip = ((unsigned long)cur->addr) & ~0xFULL;
		ia64_psr(regs)->ri = ((unsigned long)cur->addr) & 0xf;
		if (kcb->kprobe_status == KPROBE_REENTER)
			restore_previous_kprobe(kcb);
		else
			reset_current_kprobe();
		preempt_enable_no_resched();
		break;
	case KPROBE_HIT_ACTIVE:
	case KPROBE_HIT_SSDONE:
		/*
		 * In case the user-specified fault handler returned
		 * zero, try to fix up.
		 */
		if (ia64_done_with_exception(regs))
			return 1;

		/*
		 * Let ia64_do_page_fault() fix it.
		 */
		break;
	default:
		break;
	}

	return 0;
}

int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
				       unsigned long val, void *data)
{
	struct die_args *args = (struct die_args *)data;
	int ret = NOTIFY_DONE;

	if (args->regs && user_mode(args->regs))
		return ret;

	switch(val) {
	case DIE_BREAK:
		/* err is break number from ia64_bad_break() */
		if ((args->err >> 12) == (__IA64_BREAK_KPROBE >> 12)
			|| args->err == 0)
			if (pre_kprobes_handler(args))
				ret = NOTIFY_STOP;
		break;
	case DIE_FAULT:
		/* err is vector number from ia64_fault() */
		if (args->err == 36)
			if (post_kprobes_handler(args->regs))
				ret = NOTIFY_STOP;
		break;
	default:
		break;
	}
	return ret;
}

static struct kprobe trampoline_p = {
	.pre_handler = trampoline_probe_handler
};

int __init arch_init_kprobes(void)
{
	trampoline_p.addr =
		dereference_function_descriptor(__kretprobe_trampoline);
	return register_kprobe(&trampoline_p);
}

int __kprobes arch_trampoline_kprobe(struct kprobe *p)
{
	if (p->addr ==
		dereference_function_descriptor(__kretprobe_trampoline))
		return 1;

	return 0;
}