summaryrefslogtreecommitdiff
path: root/arch/x86/lib/insn.c
blob: 1bb155a0955b3b851e9d0cccbfe0726c5759085d (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
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * x86 instruction analysis
 *
 * Copyright (C) IBM Corporation, 2002, 2004, 2009
 */

#include <linux/kernel.h>
#ifdef __KERNEL__
#include <linux/string.h>
#else
#include <string.h>
#endif
#include <asm/inat.h> /*__ignore_sync_check__ */
#include <asm/insn.h> /* __ignore_sync_check__ */
#include <asm/unaligned.h> /* __ignore_sync_check__ */

#include <linux/errno.h>
#include <linux/kconfig.h>

#include <asm/emulate_prefix.h> /* __ignore_sync_check__ */

#define leXX_to_cpu(t, r)						\
({									\
	__typeof__(t) v;						\
	switch (sizeof(t)) {						\
	case 4: v = le32_to_cpu(r); break;				\
	case 2: v = le16_to_cpu(r); break;				\
	case 1:	v = r; break;						\
	default:							\
		BUILD_BUG(); break;					\
	}								\
	v;								\
})

/* Verify next sizeof(t) bytes can be on the same instruction */
#define validate_next(t, insn, n)	\
	((insn)->next_byte + sizeof(t) + n <= (insn)->end_kaddr)

#define __get_next(t, insn)	\
	({ t r = get_unaligned((t *)(insn)->next_byte); (insn)->next_byte += sizeof(t); leXX_to_cpu(t, r); })

#define __peek_nbyte_next(t, insn, n)	\
	({ t r = get_unaligned((t *)(insn)->next_byte + n); leXX_to_cpu(t, r); })

#define get_next(t, insn)	\
	({ if (unlikely(!validate_next(t, insn, 0))) goto err_out; __get_next(t, insn); })

#define peek_nbyte_next(t, insn, n)	\
	({ if (unlikely(!validate_next(t, insn, n))) goto err_out; __peek_nbyte_next(t, insn, n); })

#define peek_next(t, insn)	peek_nbyte_next(t, insn, 0)

/**
 * insn_init() - initialize struct insn
 * @insn:	&struct insn to be initialized
 * @kaddr:	address (in kernel memory) of instruction (or copy thereof)
 * @buf_len:	length of the insn buffer at @kaddr
 * @x86_64:	!0 for 64-bit kernel or 64-bit app
 */
void insn_init(struct insn *insn, const void *kaddr, int buf_len, int x86_64)
{
	/*
	 * Instructions longer than MAX_INSN_SIZE (15 bytes) are invalid
	 * even if the input buffer is long enough to hold them.
	 */
	if (buf_len > MAX_INSN_SIZE)
		buf_len = MAX_INSN_SIZE;

	memset(insn, 0, sizeof(*insn));
	insn->kaddr = kaddr;
	insn->end_kaddr = kaddr + buf_len;
	insn->next_byte = kaddr;
	insn->x86_64 = x86_64;
	insn->opnd_bytes = 4;
	if (x86_64)
		insn->addr_bytes = 8;
	else
		insn->addr_bytes = 4;
}

static const insn_byte_t xen_prefix[] = { __XEN_EMULATE_PREFIX };
static const insn_byte_t kvm_prefix[] = { __KVM_EMULATE_PREFIX };

static int __insn_get_emulate_prefix(struct insn *insn,
				     const insn_byte_t *prefix, size_t len)
{
	size_t i;

	for (i = 0; i < len; i++) {
		if (peek_nbyte_next(insn_byte_t, insn, i) != prefix[i])
			goto err_out;
	}

	insn->emulate_prefix_size = len;
	insn->next_byte += len;

	return 1;

err_out:
	return 0;
}

static void insn_get_emulate_prefix(struct insn *insn)
{
	if (__insn_get_emulate_prefix(insn, xen_prefix, sizeof(xen_prefix)))
		return;

	__insn_get_emulate_prefix(insn, kvm_prefix, sizeof(kvm_prefix));
}

/**
 * insn_get_prefixes - scan x86 instruction prefix bytes
 * @insn:	&struct insn containing instruction
 *
 * Populates the @insn->prefixes bitmap, and updates @insn->next_byte
 * to point to the (first) opcode.  No effect if @insn->prefixes.got
 * is already set.
 *
 * * Returns:
 * 0:  on success
 * < 0: on error
 */
int insn_get_prefixes(struct insn *insn)
{
	struct insn_field *prefixes = &insn->prefixes;
	insn_attr_t attr;
	insn_byte_t b, lb;
	int i, nb;

	if (prefixes->got)
		return 0;

	insn_get_emulate_prefix(insn);

	nb = 0;
	lb = 0;
	b = peek_next(insn_byte_t, insn);
	attr = inat_get_opcode_attribute(b);
	while (inat_is_legacy_prefix(attr)) {
		/* Skip if same prefix */
		for (i = 0; i < nb; i++)
			if (prefixes->bytes[i] == b)
				goto found;
		if (nb == 4)
			/* Invalid instruction */
			break;
		prefixes->bytes[nb++] = b;
		if (inat_is_address_size_prefix(attr)) {
			/* address size switches 2/4 or 4/8 */
			if (insn->x86_64)
				insn->addr_bytes ^= 12;
			else
				insn->addr_bytes ^= 6;
		} else if (inat_is_operand_size_prefix(attr)) {
			/* oprand size switches 2/4 */
			insn->opnd_bytes ^= 6;
		}
found:
		prefixes->nbytes++;
		insn->next_byte++;
		lb = b;
		b = peek_next(insn_byte_t, insn);
		attr = inat_get_opcode_attribute(b);
	}
	/* Set the last prefix */
	if (lb && lb != insn->prefixes.bytes[3]) {
		if (unlikely(insn->prefixes.bytes[3])) {
			/* Swap the last prefix */
			b = insn->prefixes.bytes[3];
			for (i = 0; i < nb; i++)
				if (prefixes->bytes[i] == lb)
					insn_set_byte(prefixes, i, b);
		}
		insn_set_byte(&insn->prefixes, 3, lb);
	}

	/* Decode REX prefix */
	if (insn->x86_64) {
		b = peek_next(insn_byte_t, insn);
		attr = inat_get_opcode_attribute(b);
		if (inat_is_rex_prefix(attr)) {
			insn_field_set(&insn->rex_prefix, b, 1);
			insn->next_byte++;
			if (X86_REX_W(b))
				/* REX.W overrides opnd_size */
				insn->opnd_bytes = 8;
		}
	}
	insn->rex_prefix.got = 1;

	/* Decode VEX prefix */
	b = peek_next(insn_byte_t, insn);
	attr = inat_get_opcode_attribute(b);
	if (inat_is_vex_prefix(attr)) {
		insn_byte_t b2 = peek_nbyte_next(insn_byte_t, insn, 1);
		if (!insn->x86_64) {
			/*
			 * In 32-bits mode, if the [7:6] bits (mod bits of
			 * ModRM) on the second byte are not 11b, it is
			 * LDS or LES or BOUND.
			 */
			if (X86_MODRM_MOD(b2) != 3)
				goto vex_end;
		}
		insn_set_byte(&insn->vex_prefix, 0, b);
		insn_set_byte(&insn->vex_prefix, 1, b2);
		if (inat_is_evex_prefix(attr)) {
			b2 = peek_nbyte_next(insn_byte_t, insn, 2);
			insn_set_byte(&insn->vex_prefix, 2, b2);
			b2 = peek_nbyte_next(insn_byte_t, insn, 3);
			insn_set_byte(&insn->vex_prefix, 3, b2);
			insn->vex_prefix.nbytes = 4;
			insn->next_byte += 4;
			if (insn->x86_64 && X86_VEX_W(b2))
				/* VEX.W overrides opnd_size */
				insn->opnd_bytes = 8;
		} else if (inat_is_vex3_prefix(attr)) {
			b2 = peek_nbyte_next(insn_byte_t, insn, 2);
			insn_set_byte(&insn->vex_prefix, 2, b2);
			insn->vex_prefix.nbytes = 3;
			insn->next_byte += 3;
			if (insn->x86_64 && X86_VEX_W(b2))
				/* VEX.W overrides opnd_size */
				insn->opnd_bytes = 8;
		} else {
			/*
			 * For VEX2, fake VEX3-like byte#2.
			 * Makes it easier to decode vex.W, vex.vvvv,
			 * vex.L and vex.pp. Masking with 0x7f sets vex.W == 0.
			 */
			insn_set_byte(&insn->vex_prefix, 2, b2 & 0x7f);
			insn->vex_prefix.nbytes = 2;
			insn->next_byte += 2;
		}
	}
vex_end:
	insn->vex_prefix.got = 1;

	prefixes->got = 1;

	return 0;

err_out:
	return -ENODATA;
}

/**
 * insn_get_opcode - collect opcode(s)
 * @insn:	&struct insn containing instruction
 *
 * Populates @insn->opcode, updates @insn->next_byte to point past the
 * opcode byte(s), and set @insn->attr (except for groups).
 * If necessary, first collects any preceding (prefix) bytes.
 * Sets @insn->opcode.value = opcode1.  No effect if @insn->opcode.got
 * is already 1.
 *
 * Returns:
 * 0:  on success
 * < 0: on error
 */
int insn_get_opcode(struct insn *insn)
{
	struct insn_field *opcode = &insn->opcode;
	int pfx_id, ret;
	insn_byte_t op;

	if (opcode->got)
		return 0;

	ret = insn_get_prefixes(insn);
	if (ret)
		return ret;

	/* Get first opcode */
	op = get_next(insn_byte_t, insn);
	insn_set_byte(opcode, 0, op);
	opcode->nbytes = 1;

	/* Check if there is VEX prefix or not */
	if (insn_is_avx(insn)) {
		insn_byte_t m, p;
		m = insn_vex_m_bits(insn);
		p = insn_vex_p_bits(insn);
		insn->attr = inat_get_avx_attribute(op, m, p);
		if ((inat_must_evex(insn->attr) && !insn_is_evex(insn)) ||
		    (!inat_accept_vex(insn->attr) &&
		     !inat_is_group(insn->attr))) {
			/* This instruction is bad */
			insn->attr = 0;
			return -EINVAL;
		}
		/* VEX has only 1 byte for opcode */
		goto end;
	}

	insn->attr = inat_get_opcode_attribute(op);
	while (inat_is_escape(insn->attr)) {
		/* Get escaped opcode */
		op = get_next(insn_byte_t, insn);
		opcode->bytes[opcode->nbytes++] = op;
		pfx_id = insn_last_prefix_id(insn);
		insn->attr = inat_get_escape_attribute(op, pfx_id, insn->attr);
	}

	if (inat_must_vex(insn->attr)) {
		/* This instruction is bad */
		insn->attr = 0;
		return -EINVAL;
	}
end:
	opcode->got = 1;
	return 0;

err_out:
	return -ENODATA;
}

/**
 * insn_get_modrm - collect ModRM byte, if any
 * @insn:	&struct insn containing instruction
 *
 * Populates @insn->modrm and updates @insn->next_byte to point past the
 * ModRM byte, if any.  If necessary, first collects the preceding bytes
 * (prefixes and opcode(s)).  No effect if @insn->modrm.got is already 1.
 *
 * Returns:
 * 0:  on success
 * < 0: on error
 */
int insn_get_modrm(struct insn *insn)
{
	struct insn_field *modrm = &insn->modrm;
	insn_byte_t pfx_id, mod;
	int ret;

	if (modrm->got)
		return 0;

	ret = insn_get_opcode(insn);
	if (ret)
		return ret;

	if (inat_has_modrm(insn->attr)) {
		mod = get_next(insn_byte_t, insn);
		insn_field_set(modrm, mod, 1);
		if (inat_is_group(insn->attr)) {
			pfx_id = insn_last_prefix_id(insn);
			insn->attr = inat_get_group_attribute(mod, pfx_id,
							      insn->attr);
			if (insn_is_avx(insn) && !inat_accept_vex(insn->attr)) {
				/* Bad insn */
				insn->attr = 0;
				return -EINVAL;
			}
		}
	}

	if (insn->x86_64 && inat_is_force64(insn->attr))
		insn->opnd_bytes = 8;

	modrm->got = 1;
	return 0;

err_out:
	return -ENODATA;
}


/**
 * insn_rip_relative() - Does instruction use RIP-relative addressing mode?
 * @insn:	&struct insn containing instruction
 *
 * If necessary, first collects the instruction up to and including the
 * ModRM byte.  No effect if @insn->x86_64 is 0.
 */
int insn_rip_relative(struct insn *insn)
{
	struct insn_field *modrm = &insn->modrm;
	int ret;

	if (!insn->x86_64)
		return 0;

	ret = insn_get_modrm(insn);
	if (ret)
		return 0;
	/*
	 * For rip-relative instructions, the mod field (top 2 bits)
	 * is zero and the r/m field (bottom 3 bits) is 0x5.
	 */
	return (modrm->nbytes && (modrm->bytes[0] & 0xc7) == 0x5);
}

/**
 * insn_get_sib() - Get the SIB byte of instruction
 * @insn:	&struct insn containing instruction
 *
 * If necessary, first collects the instruction up to and including the
 * ModRM byte.
 *
 * Returns:
 * 0: if decoding succeeded
 * < 0: otherwise.
 */
int insn_get_sib(struct insn *insn)
{
	insn_byte_t modrm;
	int ret;

	if (insn->sib.got)
		return 0;

	ret = insn_get_modrm(insn);
	if (ret)
		return ret;

	if (insn->modrm.nbytes) {
		modrm = insn->modrm.bytes[0];
		if (insn->addr_bytes != 2 &&
		    X86_MODRM_MOD(modrm) != 3 && X86_MODRM_RM(modrm) == 4) {
			insn_field_set(&insn->sib,
				       get_next(insn_byte_t, insn), 1);
		}
	}
	insn->sib.got = 1;

	return 0;

err_out:
	return -ENODATA;
}


/**
 * insn_get_displacement() - Get the displacement of instruction
 * @insn:	&struct insn containing instruction
 *
 * If necessary, first collects the instruction up to and including the
 * SIB byte.
 * Displacement value is sign-expanded.
 *
 * * Returns:
 * 0: if decoding succeeded
 * < 0: otherwise.
 */
int insn_get_displacement(struct insn *insn)
{
	insn_byte_t mod, rm, base;
	int ret;

	if (insn->displacement.got)
		return 0;

	ret = insn_get_sib(insn);
	if (ret)
		return ret;

	if (insn->modrm.nbytes) {
		/*
		 * Interpreting the modrm byte:
		 * mod = 00 - no displacement fields (exceptions below)
		 * mod = 01 - 1-byte displacement field
		 * mod = 10 - displacement field is 4 bytes, or 2 bytes if
		 * 	address size = 2 (0x67 prefix in 32-bit mode)
		 * mod = 11 - no memory operand
		 *
		 * If address size = 2...
		 * mod = 00, r/m = 110 - displacement field is 2 bytes
		 *
		 * If address size != 2...
		 * mod != 11, r/m = 100 - SIB byte exists
		 * mod = 00, SIB base = 101 - displacement field is 4 bytes
		 * mod = 00, r/m = 101 - rip-relative addressing, displacement
		 * 	field is 4 bytes
		 */
		mod = X86_MODRM_MOD(insn->modrm.value);
		rm = X86_MODRM_RM(insn->modrm.value);
		base = X86_SIB_BASE(insn->sib.value);
		if (mod == 3)
			goto out;
		if (mod == 1) {
			insn_field_set(&insn->displacement,
				       get_next(signed char, insn), 1);
		} else if (insn->addr_bytes == 2) {
			if ((mod == 0 && rm == 6) || mod == 2) {
				insn_field_set(&insn->displacement,
					       get_next(short, insn), 2);
			}
		} else {
			if ((mod == 0 && rm == 5) || mod == 2 ||
			    (mod == 0 && base == 5)) {
				insn_field_set(&insn->displacement,
					       get_next(int, insn), 4);
			}
		}
	}
out:
	insn->displacement.got = 1;
	return 0;

err_out:
	return -ENODATA;
}

/* Decode moffset16/32/64. Return 0 if failed */
static int __get_moffset(struct insn *insn)
{
	switch (insn->addr_bytes) {
	case 2:
		insn_field_set(&insn->moffset1, get_next(short, insn), 2);
		break;
	case 4:
		insn_field_set(&insn->moffset1, get_next(int, insn), 4);
		break;
	case 8:
		insn_field_set(&insn->moffset1, get_next(int, insn), 4);
		insn_field_set(&insn->moffset2, get_next(int, insn), 4);
		break;
	default:	/* opnd_bytes must be modified manually */
		goto err_out;
	}
	insn->moffset1.got = insn->moffset2.got = 1;

	return 1;

err_out:
	return 0;
}

/* Decode imm v32(Iz). Return 0 if failed */
static int __get_immv32(struct insn *insn)
{
	switch (insn->opnd_bytes) {
	case 2:
		insn_field_set(&insn->immediate, get_next(short, insn), 2);
		break;
	case 4:
	case 8:
		insn_field_set(&insn->immediate, get_next(int, insn), 4);
		break;
	default:	/* opnd_bytes must be modified manually */
		goto err_out;
	}

	return 1;

err_out:
	return 0;
}

/* Decode imm v64(Iv/Ov), Return 0 if failed */
static int __get_immv(struct insn *insn)
{
	switch (insn->opnd_bytes) {
	case 2:
		insn_field_set(&insn->immediate1, get_next(short, insn), 2);
		break;
	case 4:
		insn_field_set(&insn->immediate1, get_next(int, insn), 4);
		insn->immediate1.nbytes = 4;
		break;
	case 8:
		insn_field_set(&insn->immediate1, get_next(int, insn), 4);
		insn_field_set(&insn->immediate2, get_next(int, insn), 4);
		break;
	default:	/* opnd_bytes must be modified manually */
		goto err_out;
	}
	insn->immediate1.got = insn->immediate2.got = 1;

	return 1;
err_out:
	return 0;
}

/* Decode ptr16:16/32(Ap) */
static int __get_immptr(struct insn *insn)
{
	switch (insn->opnd_bytes) {
	case 2:
		insn_field_set(&insn->immediate1, get_next(short, insn), 2);
		break;
	case 4:
		insn_field_set(&insn->immediate1, get_next(int, insn), 4);
		break;
	case 8:
		/* ptr16:64 is not exist (no segment) */
		return 0;
	default:	/* opnd_bytes must be modified manually */
		goto err_out;
	}
	insn_field_set(&insn->immediate2, get_next(unsigned short, insn), 2);
	insn->immediate1.got = insn->immediate2.got = 1;

	return 1;
err_out:
	return 0;
}

/**
 * insn_get_immediate() - Get the immediate in an instruction
 * @insn:	&struct insn containing instruction
 *
 * If necessary, first collects the instruction up to and including the
 * displacement bytes.
 * Basically, most of immediates are sign-expanded. Unsigned-value can be
 * computed by bit masking with ((1 << (nbytes * 8)) - 1)
 *
 * Returns:
 * 0:  on success
 * < 0: on error
 */
int insn_get_immediate(struct insn *insn)
{
	int ret;

	if (insn->immediate.got)
		return 0;

	ret = insn_get_displacement(insn);
	if (ret)
		return ret;

	if (inat_has_moffset(insn->attr)) {
		if (!__get_moffset(insn))
			goto err_out;
		goto done;
	}

	if (!inat_has_immediate(insn->attr))
		/* no immediates */
		goto done;

	switch (inat_immediate_size(insn->attr)) {
	case INAT_IMM_BYTE:
		insn_field_set(&insn->immediate, get_next(signed char, insn), 1);
		break;
	case INAT_IMM_WORD:
		insn_field_set(&insn->immediate, get_next(short, insn), 2);
		break;
	case INAT_IMM_DWORD:
		insn_field_set(&insn->immediate, get_next(int, insn), 4);
		break;
	case INAT_IMM_QWORD:
		insn_field_set(&insn->immediate1, get_next(int, insn), 4);
		insn_field_set(&insn->immediate2, get_next(int, insn), 4);
		break;
	case INAT_IMM_PTR:
		if (!__get_immptr(insn))
			goto err_out;
		break;
	case INAT_IMM_VWORD32:
		if (!__get_immv32(insn))
			goto err_out;
		break;
	case INAT_IMM_VWORD:
		if (!__get_immv(insn))
			goto err_out;
		break;
	default:
		/* Here, insn must have an immediate, but failed */
		goto err_out;
	}
	if (inat_has_second_immediate(insn->attr)) {
		insn_field_set(&insn->immediate2, get_next(signed char, insn), 1);
	}
done:
	insn->immediate.got = 1;
	return 0;

err_out:
	return -ENODATA;
}

/**
 * insn_get_length() - Get the length of instruction
 * @insn:	&struct insn containing instruction
 *
 * If necessary, first collects the instruction up to and including the
 * immediates bytes.
 *
 * Returns:
 *  - 0 on success
 *  - < 0 on error
*/
int insn_get_length(struct insn *insn)
{
	int ret;

	if (insn->length)
		return 0;

	ret = insn_get_immediate(insn);
	if (ret)
		return ret;

	insn->length = (unsigned char)((unsigned long)insn->next_byte
				     - (unsigned long)insn->kaddr);

	return 0;
}

/* Ensure this instruction is decoded completely */
static inline int insn_complete(struct insn *insn)
{
	return insn->opcode.got && insn->modrm.got && insn->sib.got &&
		insn->displacement.got && insn->immediate.got;
}

/**
 * insn_decode() - Decode an x86 instruction
 * @insn:	&struct insn to be initialized
 * @kaddr:	address (in kernel memory) of instruction (or copy thereof)
 * @buf_len:	length of the insn buffer at @kaddr
 * @m:		insn mode, see enum insn_mode
 *
 * Returns:
 * 0: if decoding succeeded
 * < 0: otherwise.
 */
int insn_decode(struct insn *insn, const void *kaddr, int buf_len, enum insn_mode m)
{
	int ret;

/* #define INSN_MODE_KERN	-1 __ignore_sync_check__ mode is only valid in the kernel */

	if (m == INSN_MODE_KERN)
		insn_init(insn, kaddr, buf_len, IS_ENABLED(CONFIG_X86_64));
	else
		insn_init(insn, kaddr, buf_len, m == INSN_MODE_64);

	ret = insn_get_length(insn);
	if (ret)
		return ret;

	if (insn_complete(insn))
		return 0;

	return -EINVAL;
}