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  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * x86 instruction analysis
  4 *
  5 * Copyright (C) IBM Corporation, 2002, 2004, 2009
  6 */
  7
  8#include <linux/kernel.h>
  9#ifdef __KERNEL__
 10#include <linux/string.h>
 11#else
 12#include <string.h>
 13#endif
 14#include "../include/asm/inat.h" /* __ignore_sync_check__ */
 15#include "../include/asm/insn.h" /* __ignore_sync_check__ */
 16#include "../include/linux/unaligned.h" /* __ignore_sync_check__ */
 17
 18#include <linux/errno.h>
 19#include <linux/kconfig.h>
 20
 21#include "../include/asm/emulate_prefix.h" /* __ignore_sync_check__ */
 22
 23#define leXX_to_cpu(t, r)						\
 24({									\
 25	__typeof__(t) v;						\
 26	switch (sizeof(t)) {						\
 27	case 4: v = le32_to_cpu(r); break;				\
 28	case 2: v = le16_to_cpu(r); break;				\
 29	case 1:	v = r; break;						\
 30	default:							\
 31		BUILD_BUG(); break;					\
 32	}								\
 33	v;								\
 34})
 35
 36/* Verify next sizeof(t) bytes can be on the same instruction */
 37#define validate_next(t, insn, n)	\
 38	((insn)->next_byte + sizeof(t) + n <= (insn)->end_kaddr)
 39
 40#define __get_next(t, insn)	\
 41	({ t r = get_unaligned((t *)(insn)->next_byte); (insn)->next_byte += sizeof(t); leXX_to_cpu(t, r); })
 42
 43#define __peek_nbyte_next(t, insn, n)	\
 44	({ t r = get_unaligned((t *)(insn)->next_byte + n); leXX_to_cpu(t, r); })
 45
 46#define get_next(t, insn)	\
 47	({ if (unlikely(!validate_next(t, insn, 0))) goto err_out; __get_next(t, insn); })
 48
 49#define peek_nbyte_next(t, insn, n)	\
 50	({ if (unlikely(!validate_next(t, insn, n))) goto err_out; __peek_nbyte_next(t, insn, n); })
 51
 52#define peek_next(t, insn)	peek_nbyte_next(t, insn, 0)
 53
 54/**
 55 * insn_init() - initialize struct insn
 56 * @insn:	&struct insn to be initialized
 57 * @kaddr:	address (in kernel memory) of instruction (or copy thereof)
 58 * @buf_len:	length of the insn buffer at @kaddr
 59 * @x86_64:	!0 for 64-bit kernel or 64-bit app
 60 */
 61void insn_init(struct insn *insn, const void *kaddr, int buf_len, int x86_64)
 62{
 63	/*
 64	 * Instructions longer than MAX_INSN_SIZE (15 bytes) are invalid
 65	 * even if the input buffer is long enough to hold them.
 66	 */
 67	if (buf_len > MAX_INSN_SIZE)
 68		buf_len = MAX_INSN_SIZE;
 69
 70	memset(insn, 0, sizeof(*insn));
 71	insn->kaddr = kaddr;
 72	insn->end_kaddr = kaddr + buf_len;
 73	insn->next_byte = kaddr;
 74	insn->x86_64 = x86_64;
 75	insn->opnd_bytes = 4;
 76	if (x86_64)
 77		insn->addr_bytes = 8;
 78	else
 79		insn->addr_bytes = 4;
 80}
 81
 82static const insn_byte_t xen_prefix[] = { __XEN_EMULATE_PREFIX };
 83static const insn_byte_t kvm_prefix[] = { __KVM_EMULATE_PREFIX };
 84
 85static int __insn_get_emulate_prefix(struct insn *insn,
 86				     const insn_byte_t *prefix, size_t len)
 87{
 88	size_t i;
 89
 90	for (i = 0; i < len; i++) {
 91		if (peek_nbyte_next(insn_byte_t, insn, i) != prefix[i])
 92			goto err_out;
 93	}
 94
 95	insn->emulate_prefix_size = len;
 96	insn->next_byte += len;
 97
 98	return 1;
 99
100err_out:
101	return 0;
102}
103
104static void insn_get_emulate_prefix(struct insn *insn)
105{
106	if (__insn_get_emulate_prefix(insn, xen_prefix, sizeof(xen_prefix)))
107		return;
108
109	__insn_get_emulate_prefix(insn, kvm_prefix, sizeof(kvm_prefix));
110}
111
112/**
113 * insn_get_prefixes - scan x86 instruction prefix bytes
114 * @insn:	&struct insn containing instruction
115 *
116 * Populates the @insn->prefixes bitmap, and updates @insn->next_byte
117 * to point to the (first) opcode.  No effect if @insn->prefixes.got
118 * is already set.
119 *
120 * * Returns:
121 * 0:  on success
122 * < 0: on error
123 */
124int insn_get_prefixes(struct insn *insn)
125{
126	struct insn_field *prefixes = &insn->prefixes;
127	insn_attr_t attr;
128	insn_byte_t b, lb;
129	int i, nb;
130
131	if (prefixes->got)
132		return 0;
133
134	insn_get_emulate_prefix(insn);
135
136	nb = 0;
137	lb = 0;
138	b = peek_next(insn_byte_t, insn);
139	attr = inat_get_opcode_attribute(b);
140	while (inat_is_legacy_prefix(attr)) {
141		/* Skip if same prefix */
142		for (i = 0; i < nb; i++)
143			if (prefixes->bytes[i] == b)
144				goto found;
145		if (nb == 4)
146			/* Invalid instruction */
147			break;
148		prefixes->bytes[nb++] = b;
149		if (inat_is_address_size_prefix(attr)) {
150			/* address size switches 2/4 or 4/8 */
151			if (insn->x86_64)
152				insn->addr_bytes ^= 12;
153			else
154				insn->addr_bytes ^= 6;
155		} else if (inat_is_operand_size_prefix(attr)) {
156			/* oprand size switches 2/4 */
157			insn->opnd_bytes ^= 6;
158		}
159found:
160		prefixes->nbytes++;
161		insn->next_byte++;
162		lb = b;
163		b = peek_next(insn_byte_t, insn);
164		attr = inat_get_opcode_attribute(b);
165	}
166	/* Set the last prefix */
167	if (lb && lb != insn->prefixes.bytes[3]) {
168		if (unlikely(insn->prefixes.bytes[3])) {
169			/* Swap the last prefix */
170			b = insn->prefixes.bytes[3];
171			for (i = 0; i < nb; i++)
172				if (prefixes->bytes[i] == lb)
173					insn_set_byte(prefixes, i, b);
174		}
175		insn_set_byte(&insn->prefixes, 3, lb);
176	}
177
178	/* Decode REX prefix */
179	if (insn->x86_64) {
180		b = peek_next(insn_byte_t, insn);
181		attr = inat_get_opcode_attribute(b);
182		if (inat_is_rex_prefix(attr)) {
183			insn_field_set(&insn->rex_prefix, b, 1);
184			insn->next_byte++;
185			if (X86_REX_W(b))
186				/* REX.W overrides opnd_size */
187				insn->opnd_bytes = 8;
188		} else if (inat_is_rex2_prefix(attr)) {
189			insn_set_byte(&insn->rex_prefix, 0, b);
190			b = peek_nbyte_next(insn_byte_t, insn, 1);
191			insn_set_byte(&insn->rex_prefix, 1, b);
192			insn->rex_prefix.nbytes = 2;
193			insn->next_byte += 2;
194			if (X86_REX_W(b))
195				/* REX.W overrides opnd_size */
196				insn->opnd_bytes = 8;
197			insn->rex_prefix.got = 1;
198			goto vex_end;
199		}
200	}
201	insn->rex_prefix.got = 1;
202
203	/* Decode VEX prefix */
204	b = peek_next(insn_byte_t, insn);
205	attr = inat_get_opcode_attribute(b);
206	if (inat_is_vex_prefix(attr)) {
207		insn_byte_t b2 = peek_nbyte_next(insn_byte_t, insn, 1);
208		if (!insn->x86_64) {
209			/*
210			 * In 32-bits mode, if the [7:6] bits (mod bits of
211			 * ModRM) on the second byte are not 11b, it is
212			 * LDS or LES or BOUND.
213			 */
214			if (X86_MODRM_MOD(b2) != 3)
215				goto vex_end;
216		}
217		insn_set_byte(&insn->vex_prefix, 0, b);
218		insn_set_byte(&insn->vex_prefix, 1, b2);
219		if (inat_is_evex_prefix(attr)) {
220			b2 = peek_nbyte_next(insn_byte_t, insn, 2);
221			insn_set_byte(&insn->vex_prefix, 2, b2);
222			b2 = peek_nbyte_next(insn_byte_t, insn, 3);
223			insn_set_byte(&insn->vex_prefix, 3, b2);
224			insn->vex_prefix.nbytes = 4;
225			insn->next_byte += 4;
226			if (insn->x86_64 && X86_VEX_W(b2))
227				/* VEX.W overrides opnd_size */
228				insn->opnd_bytes = 8;
229		} else if (inat_is_vex3_prefix(attr)) {
230			b2 = peek_nbyte_next(insn_byte_t, insn, 2);
231			insn_set_byte(&insn->vex_prefix, 2, b2);
232			insn->vex_prefix.nbytes = 3;
233			insn->next_byte += 3;
234			if (insn->x86_64 && X86_VEX_W(b2))
235				/* VEX.W overrides opnd_size */
236				insn->opnd_bytes = 8;
237		} else {
238			/*
239			 * For VEX2, fake VEX3-like byte#2.
240			 * Makes it easier to decode vex.W, vex.vvvv,
241			 * vex.L and vex.pp. Masking with 0x7f sets vex.W == 0.
242			 */
243			insn_set_byte(&insn->vex_prefix, 2, b2 & 0x7f);
244			insn->vex_prefix.nbytes = 2;
245			insn->next_byte += 2;
246		}
247	}
248vex_end:
249	insn->vex_prefix.got = 1;
250
251	prefixes->got = 1;
252
253	return 0;
254
255err_out:
256	return -ENODATA;
257}
258
259/**
260 * insn_get_opcode - collect opcode(s)
261 * @insn:	&struct insn containing instruction
262 *
263 * Populates @insn->opcode, updates @insn->next_byte to point past the
264 * opcode byte(s), and set @insn->attr (except for groups).
265 * If necessary, first collects any preceding (prefix) bytes.
266 * Sets @insn->opcode.value = opcode1.  No effect if @insn->opcode.got
267 * is already 1.
268 *
269 * Returns:
270 * 0:  on success
271 * < 0: on error
272 */
273int insn_get_opcode(struct insn *insn)
274{
275	struct insn_field *opcode = &insn->opcode;
276	int pfx_id, ret;
277	insn_byte_t op;
278
279	if (opcode->got)
280		return 0;
281
282	ret = insn_get_prefixes(insn);
283	if (ret)
284		return ret;
285
286	/* Get first opcode */
287	op = get_next(insn_byte_t, insn);
288	insn_set_byte(opcode, 0, op);
289	opcode->nbytes = 1;
290
291	/* Check if there is VEX prefix or not */
292	if (insn_is_avx(insn)) {
293		insn_byte_t m, p;
294		m = insn_vex_m_bits(insn);
295		p = insn_vex_p_bits(insn);
296		insn->attr = inat_get_avx_attribute(op, m, p);
297		/* SCALABLE EVEX uses p bits to encode operand size */
298		if (inat_evex_scalable(insn->attr) && !insn_vex_w_bit(insn) &&
299		    p == INAT_PFX_OPNDSZ)
300			insn->opnd_bytes = 2;
301		if ((inat_must_evex(insn->attr) && !insn_is_evex(insn)) ||
302		    (!inat_accept_vex(insn->attr) &&
303		     !inat_is_group(insn->attr))) {
304			/* This instruction is bad */
305			insn->attr = 0;
306			return -EINVAL;
307		}
308		/* VEX has only 1 byte for opcode */
309		goto end;
310	}
311
312	/* Check if there is REX2 prefix or not */
313	if (insn_is_rex2(insn)) {
314		if (insn_rex2_m_bit(insn)) {
315			/* map 1 is escape 0x0f */
316			insn_attr_t esc_attr = inat_get_opcode_attribute(0x0f);
317
318			pfx_id = insn_last_prefix_id(insn);
319			insn->attr = inat_get_escape_attribute(op, pfx_id, esc_attr);
320		} else {
321			insn->attr = inat_get_opcode_attribute(op);
322		}
323		goto end;
324	}
325
326	insn->attr = inat_get_opcode_attribute(op);
327	while (inat_is_escape(insn->attr)) {
328		/* Get escaped opcode */
329		op = get_next(insn_byte_t, insn);
330		opcode->bytes[opcode->nbytes++] = op;
331		pfx_id = insn_last_prefix_id(insn);
332		insn->attr = inat_get_escape_attribute(op, pfx_id, insn->attr);
333	}
334
335	if (inat_must_vex(insn->attr)) {
336		/* This instruction is bad */
337		insn->attr = 0;
338		return -EINVAL;
339	}
340end:
341	opcode->got = 1;
342	return 0;
343
344err_out:
345	return -ENODATA;
346}
347
348/**
349 * insn_get_modrm - collect ModRM byte, if any
350 * @insn:	&struct insn containing instruction
351 *
352 * Populates @insn->modrm and updates @insn->next_byte to point past the
353 * ModRM byte, if any.  If necessary, first collects the preceding bytes
354 * (prefixes and opcode(s)).  No effect if @insn->modrm.got is already 1.
355 *
356 * Returns:
357 * 0:  on success
358 * < 0: on error
359 */
360int insn_get_modrm(struct insn *insn)
361{
362	struct insn_field *modrm = &insn->modrm;
363	insn_byte_t pfx_id, mod;
364	int ret;
365
366	if (modrm->got)
367		return 0;
368
369	ret = insn_get_opcode(insn);
370	if (ret)
371		return ret;
372
373	if (inat_has_modrm(insn->attr)) {
374		mod = get_next(insn_byte_t, insn);
375		insn_field_set(modrm, mod, 1);
376		if (inat_is_group(insn->attr)) {
377			pfx_id = insn_last_prefix_id(insn);
378			insn->attr = inat_get_group_attribute(mod, pfx_id,
379							      insn->attr);
380			if (insn_is_avx(insn) && !inat_accept_vex(insn->attr)) {
381				/* Bad insn */
382				insn->attr = 0;
383				return -EINVAL;
384			}
385		}
386	}
387
388	if (insn->x86_64 && inat_is_force64(insn->attr))
389		insn->opnd_bytes = 8;
390
391	modrm->got = 1;
392	return 0;
393
394err_out:
395	return -ENODATA;
396}
397
398
399/**
400 * insn_rip_relative() - Does instruction use RIP-relative addressing mode?
401 * @insn:	&struct insn containing instruction
402 *
403 * If necessary, first collects the instruction up to and including the
404 * ModRM byte.  No effect if @insn->x86_64 is 0.
405 */
406int insn_rip_relative(struct insn *insn)
407{
408	struct insn_field *modrm = &insn->modrm;
409	int ret;
410
411	if (!insn->x86_64)
412		return 0;
413
414	ret = insn_get_modrm(insn);
415	if (ret)
416		return 0;
417	/*
418	 * For rip-relative instructions, the mod field (top 2 bits)
419	 * is zero and the r/m field (bottom 3 bits) is 0x5.
420	 */
421	return (modrm->nbytes && (modrm->bytes[0] & 0xc7) == 0x5);
422}
423
424/**
425 * insn_get_sib() - Get the SIB byte of instruction
426 * @insn:	&struct insn containing instruction
427 *
428 * If necessary, first collects the instruction up to and including the
429 * ModRM byte.
430 *
431 * Returns:
432 * 0: if decoding succeeded
433 * < 0: otherwise.
434 */
435int insn_get_sib(struct insn *insn)
436{
437	insn_byte_t modrm;
438	int ret;
439
440	if (insn->sib.got)
441		return 0;
442
443	ret = insn_get_modrm(insn);
444	if (ret)
445		return ret;
446
447	if (insn->modrm.nbytes) {
448		modrm = insn->modrm.bytes[0];
449		if (insn->addr_bytes != 2 &&
450		    X86_MODRM_MOD(modrm) != 3 && X86_MODRM_RM(modrm) == 4) {
451			insn_field_set(&insn->sib,
452				       get_next(insn_byte_t, insn), 1);
453		}
454	}
455	insn->sib.got = 1;
456
457	return 0;
458
459err_out:
460	return -ENODATA;
461}
462
463
464/**
465 * insn_get_displacement() - Get the displacement of instruction
466 * @insn:	&struct insn containing instruction
467 *
468 * If necessary, first collects the instruction up to and including the
469 * SIB byte.
470 * Displacement value is sign-expanded.
471 *
472 * * Returns:
473 * 0: if decoding succeeded
474 * < 0: otherwise.
475 */
476int insn_get_displacement(struct insn *insn)
477{
478	insn_byte_t mod, rm, base;
479	int ret;
480
481	if (insn->displacement.got)
482		return 0;
483
484	ret = insn_get_sib(insn);
485	if (ret)
486		return ret;
487
488	if (insn->modrm.nbytes) {
489		/*
490		 * Interpreting the modrm byte:
491		 * mod = 00 - no displacement fields (exceptions below)
492		 * mod = 01 - 1-byte displacement field
493		 * mod = 10 - displacement field is 4 bytes, or 2 bytes if
494		 * 	address size = 2 (0x67 prefix in 32-bit mode)
495		 * mod = 11 - no memory operand
496		 *
497		 * If address size = 2...
498		 * mod = 00, r/m = 110 - displacement field is 2 bytes
499		 *
500		 * If address size != 2...
501		 * mod != 11, r/m = 100 - SIB byte exists
502		 * mod = 00, SIB base = 101 - displacement field is 4 bytes
503		 * mod = 00, r/m = 101 - rip-relative addressing, displacement
504		 * 	field is 4 bytes
505		 */
506		mod = X86_MODRM_MOD(insn->modrm.value);
507		rm = X86_MODRM_RM(insn->modrm.value);
508		base = X86_SIB_BASE(insn->sib.value);
509		if (mod == 3)
510			goto out;
511		if (mod == 1) {
512			insn_field_set(&insn->displacement,
513				       get_next(signed char, insn), 1);
514		} else if (insn->addr_bytes == 2) {
515			if ((mod == 0 && rm == 6) || mod == 2) {
516				insn_field_set(&insn->displacement,
517					       get_next(short, insn), 2);
518			}
519		} else {
520			if ((mod == 0 && rm == 5) || mod == 2 ||
521			    (mod == 0 && base == 5)) {
522				insn_field_set(&insn->displacement,
523					       get_next(int, insn), 4);
524			}
525		}
526	}
527out:
528	insn->displacement.got = 1;
529	return 0;
530
531err_out:
532	return -ENODATA;
533}
534
535/* Decode moffset16/32/64. Return 0 if failed */
536static int __get_moffset(struct insn *insn)
537{
538	switch (insn->addr_bytes) {
539	case 2:
540		insn_field_set(&insn->moffset1, get_next(short, insn), 2);
541		break;
542	case 4:
543		insn_field_set(&insn->moffset1, get_next(int, insn), 4);
544		break;
545	case 8:
546		insn_field_set(&insn->moffset1, get_next(int, insn), 4);
547		insn_field_set(&insn->moffset2, get_next(int, insn), 4);
548		break;
549	default:	/* opnd_bytes must be modified manually */
550		goto err_out;
551	}
552	insn->moffset1.got = insn->moffset2.got = 1;
553
554	return 1;
555
556err_out:
557	return 0;
558}
559
560/* Decode imm v32(Iz). Return 0 if failed */
561static int __get_immv32(struct insn *insn)
562{
563	switch (insn->opnd_bytes) {
564	case 2:
565		insn_field_set(&insn->immediate, get_next(short, insn), 2);
566		break;
567	case 4:
568	case 8:
569		insn_field_set(&insn->immediate, get_next(int, insn), 4);
570		break;
571	default:	/* opnd_bytes must be modified manually */
572		goto err_out;
573	}
574
575	return 1;
576
577err_out:
578	return 0;
579}
580
581/* Decode imm v64(Iv/Ov), Return 0 if failed */
582static int __get_immv(struct insn *insn)
583{
584	switch (insn->opnd_bytes) {
585	case 2:
586		insn_field_set(&insn->immediate1, get_next(short, insn), 2);
587		break;
588	case 4:
589		insn_field_set(&insn->immediate1, get_next(int, insn), 4);
590		insn->immediate1.nbytes = 4;
591		break;
592	case 8:
593		insn_field_set(&insn->immediate1, get_next(int, insn), 4);
594		insn_field_set(&insn->immediate2, get_next(int, insn), 4);
595		break;
596	default:	/* opnd_bytes must be modified manually */
597		goto err_out;
598	}
599	insn->immediate1.got = insn->immediate2.got = 1;
600
601	return 1;
602err_out:
603	return 0;
604}
605
606/* Decode ptr16:16/32(Ap) */
607static int __get_immptr(struct insn *insn)
608{
609	switch (insn->opnd_bytes) {
610	case 2:
611		insn_field_set(&insn->immediate1, get_next(short, insn), 2);
612		break;
613	case 4:
614		insn_field_set(&insn->immediate1, get_next(int, insn), 4);
615		break;
616	case 8:
617		/* ptr16:64 is not exist (no segment) */
618		return 0;
619	default:	/* opnd_bytes must be modified manually */
620		goto err_out;
621	}
622	insn_field_set(&insn->immediate2, get_next(unsigned short, insn), 2);
623	insn->immediate1.got = insn->immediate2.got = 1;
624
625	return 1;
626err_out:
627	return 0;
628}
629
630/**
631 * insn_get_immediate() - Get the immediate in an instruction
632 * @insn:	&struct insn containing instruction
633 *
634 * If necessary, first collects the instruction up to and including the
635 * displacement bytes.
636 * Basically, most of immediates are sign-expanded. Unsigned-value can be
637 * computed by bit masking with ((1 << (nbytes * 8)) - 1)
638 *
639 * Returns:
640 * 0:  on success
641 * < 0: on error
642 */
643int insn_get_immediate(struct insn *insn)
644{
645	int ret;
646
647	if (insn->immediate.got)
648		return 0;
649
650	ret = insn_get_displacement(insn);
651	if (ret)
652		return ret;
653
654	if (inat_has_moffset(insn->attr)) {
655		if (!__get_moffset(insn))
656			goto err_out;
657		goto done;
658	}
659
660	if (!inat_has_immediate(insn->attr))
661		/* no immediates */
662		goto done;
663
664	switch (inat_immediate_size(insn->attr)) {
665	case INAT_IMM_BYTE:
666		insn_field_set(&insn->immediate, get_next(signed char, insn), 1);
667		break;
668	case INAT_IMM_WORD:
669		insn_field_set(&insn->immediate, get_next(short, insn), 2);
670		break;
671	case INAT_IMM_DWORD:
672		insn_field_set(&insn->immediate, get_next(int, insn), 4);
673		break;
674	case INAT_IMM_QWORD:
675		insn_field_set(&insn->immediate1, get_next(int, insn), 4);
676		insn_field_set(&insn->immediate2, get_next(int, insn), 4);
677		break;
678	case INAT_IMM_PTR:
679		if (!__get_immptr(insn))
680			goto err_out;
681		break;
682	case INAT_IMM_VWORD32:
683		if (!__get_immv32(insn))
684			goto err_out;
685		break;
686	case INAT_IMM_VWORD:
687		if (!__get_immv(insn))
688			goto err_out;
689		break;
690	default:
691		/* Here, insn must have an immediate, but failed */
692		goto err_out;
693	}
694	if (inat_has_second_immediate(insn->attr)) {
695		insn_field_set(&insn->immediate2, get_next(signed char, insn), 1);
696	}
697done:
698	insn->immediate.got = 1;
699	return 0;
700
701err_out:
702	return -ENODATA;
703}
704
705/**
706 * insn_get_length() - Get the length of instruction
707 * @insn:	&struct insn containing instruction
708 *
709 * If necessary, first collects the instruction up to and including the
710 * immediates bytes.
711 *
712 * Returns:
713 *  - 0 on success
714 *  - < 0 on error
715*/
716int insn_get_length(struct insn *insn)
717{
718	int ret;
719
720	if (insn->length)
721		return 0;
722
723	ret = insn_get_immediate(insn);
724	if (ret)
725		return ret;
726
727	insn->length = (unsigned char)((unsigned long)insn->next_byte
728				     - (unsigned long)insn->kaddr);
729
730	return 0;
731}
732
733/* Ensure this instruction is decoded completely */
734static inline int insn_complete(struct insn *insn)
735{
736	return insn->opcode.got && insn->modrm.got && insn->sib.got &&
737		insn->displacement.got && insn->immediate.got;
738}
739
740/**
741 * insn_decode() - Decode an x86 instruction
742 * @insn:	&struct insn to be initialized
743 * @kaddr:	address (in kernel memory) of instruction (or copy thereof)
744 * @buf_len:	length of the insn buffer at @kaddr
745 * @m:		insn mode, see enum insn_mode
746 *
747 * Returns:
748 * 0: if decoding succeeded
749 * < 0: otherwise.
750 */
751int insn_decode(struct insn *insn, const void *kaddr, int buf_len, enum insn_mode m)
752{
753	int ret;
754
755#define INSN_MODE_KERN (enum insn_mode)-1 /* __ignore_sync_check__ mode is only valid in the kernel */
756
757	if (m == INSN_MODE_KERN)
758		insn_init(insn, kaddr, buf_len, IS_ENABLED(CONFIG_X86_64));
759	else
760		insn_init(insn, kaddr, buf_len, m == INSN_MODE_64);
761
762	ret = insn_get_length(insn);
763	if (ret)
764		return ret;
765
766	if (insn_complete(insn))
767		return 0;
768
769	return -EINVAL;
770}