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