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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 <linux/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;
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 -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}
1/*
2 * x86 instruction analysis
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
17 *
18 * Copyright (C) IBM Corporation, 2002, 2004, 2009
19 */
20
21#include <linux/string.h>
22#include <asm/inat.h>
23#include <asm/insn.h>
24
25/* Verify next sizeof(t) bytes can be on the same instruction */
26#define validate_next(t, insn, n) \
27 ((insn)->next_byte + sizeof(t) + n - (insn)->kaddr <= MAX_INSN_SIZE)
28
29#define __get_next(t, insn) \
30 ({ t r = *(t*)insn->next_byte; insn->next_byte += sizeof(t); r; })
31
32#define __peek_nbyte_next(t, insn, n) \
33 ({ t r = *(t*)((insn)->next_byte + n); r; })
34
35#define get_next(t, insn) \
36 ({ if (unlikely(!validate_next(t, insn, 0))) goto err_out; __get_next(t, insn); })
37
38#define peek_nbyte_next(t, insn, n) \
39 ({ if (unlikely(!validate_next(t, insn, n))) goto err_out; __peek_nbyte_next(t, insn, n); })
40
41#define peek_next(t, insn) peek_nbyte_next(t, insn, 0)
42
43/**
44 * insn_init() - initialize struct insn
45 * @insn: &struct insn to be initialized
46 * @kaddr: address (in kernel memory) of instruction (or copy thereof)
47 * @x86_64: !0 for 64-bit kernel or 64-bit app
48 */
49void insn_init(struct insn *insn, const void *kaddr, int x86_64)
50{
51 memset(insn, 0, sizeof(*insn));
52 insn->kaddr = kaddr;
53 insn->next_byte = kaddr;
54 insn->x86_64 = x86_64 ? 1 : 0;
55 insn->opnd_bytes = 4;
56 if (x86_64)
57 insn->addr_bytes = 8;
58 else
59 insn->addr_bytes = 4;
60}
61
62/**
63 * insn_get_prefixes - scan x86 instruction prefix bytes
64 * @insn: &struct insn containing instruction
65 *
66 * Populates the @insn->prefixes bitmap, and updates @insn->next_byte
67 * to point to the (first) opcode. No effect if @insn->prefixes.got
68 * is already set.
69 */
70void insn_get_prefixes(struct insn *insn)
71{
72 struct insn_field *prefixes = &insn->prefixes;
73 insn_attr_t attr;
74 insn_byte_t b, lb;
75 int i, nb;
76
77 if (prefixes->got)
78 return;
79
80 nb = 0;
81 lb = 0;
82 b = peek_next(insn_byte_t, insn);
83 attr = inat_get_opcode_attribute(b);
84 while (inat_is_legacy_prefix(attr)) {
85 /* Skip if same prefix */
86 for (i = 0; i < nb; i++)
87 if (prefixes->bytes[i] == b)
88 goto found;
89 if (nb == 4)
90 /* Invalid instruction */
91 break;
92 prefixes->bytes[nb++] = b;
93 if (inat_is_address_size_prefix(attr)) {
94 /* address size switches 2/4 or 4/8 */
95 if (insn->x86_64)
96 insn->addr_bytes ^= 12;
97 else
98 insn->addr_bytes ^= 6;
99 } else if (inat_is_operand_size_prefix(attr)) {
100 /* oprand size switches 2/4 */
101 insn->opnd_bytes ^= 6;
102 }
103found:
104 prefixes->nbytes++;
105 insn->next_byte++;
106 lb = b;
107 b = peek_next(insn_byte_t, insn);
108 attr = inat_get_opcode_attribute(b);
109 }
110 /* Set the last prefix */
111 if (lb && lb != insn->prefixes.bytes[3]) {
112 if (unlikely(insn->prefixes.bytes[3])) {
113 /* Swap the last prefix */
114 b = insn->prefixes.bytes[3];
115 for (i = 0; i < nb; i++)
116 if (prefixes->bytes[i] == lb)
117 prefixes->bytes[i] = b;
118 }
119 insn->prefixes.bytes[3] = lb;
120 }
121
122 /* Decode REX prefix */
123 if (insn->x86_64) {
124 b = peek_next(insn_byte_t, insn);
125 attr = inat_get_opcode_attribute(b);
126 if (inat_is_rex_prefix(attr)) {
127 insn->rex_prefix.value = b;
128 insn->rex_prefix.nbytes = 1;
129 insn->next_byte++;
130 if (X86_REX_W(b))
131 /* REX.W overrides opnd_size */
132 insn->opnd_bytes = 8;
133 }
134 }
135 insn->rex_prefix.got = 1;
136
137 /* Decode VEX prefix */
138 b = peek_next(insn_byte_t, insn);
139 attr = inat_get_opcode_attribute(b);
140 if (inat_is_vex_prefix(attr)) {
141 insn_byte_t b2 = peek_nbyte_next(insn_byte_t, insn, 1);
142 if (!insn->x86_64) {
143 /*
144 * In 32-bits mode, if the [7:6] bits (mod bits of
145 * ModRM) on the second byte are not 11b, it is
146 * LDS or LES.
147 */
148 if (X86_MODRM_MOD(b2) != 3)
149 goto vex_end;
150 }
151 insn->vex_prefix.bytes[0] = b;
152 insn->vex_prefix.bytes[1] = b2;
153 if (inat_is_vex3_prefix(attr)) {
154 b2 = peek_nbyte_next(insn_byte_t, insn, 2);
155 insn->vex_prefix.bytes[2] = b2;
156 insn->vex_prefix.nbytes = 3;
157 insn->next_byte += 3;
158 if (insn->x86_64 && X86_VEX_W(b2))
159 /* VEX.W overrides opnd_size */
160 insn->opnd_bytes = 8;
161 } else {
162 insn->vex_prefix.nbytes = 2;
163 insn->next_byte += 2;
164 }
165 }
166vex_end:
167 insn->vex_prefix.got = 1;
168
169 prefixes->got = 1;
170
171err_out:
172 return;
173}
174
175/**
176 * insn_get_opcode - collect opcode(s)
177 * @insn: &struct insn containing instruction
178 *
179 * Populates @insn->opcode, updates @insn->next_byte to point past the
180 * opcode byte(s), and set @insn->attr (except for groups).
181 * If necessary, first collects any preceding (prefix) bytes.
182 * Sets @insn->opcode.value = opcode1. No effect if @insn->opcode.got
183 * is already 1.
184 */
185void insn_get_opcode(struct insn *insn)
186{
187 struct insn_field *opcode = &insn->opcode;
188 insn_byte_t op;
189 int pfx_id;
190 if (opcode->got)
191 return;
192 if (!insn->prefixes.got)
193 insn_get_prefixes(insn);
194
195 /* Get first opcode */
196 op = get_next(insn_byte_t, insn);
197 opcode->bytes[0] = op;
198 opcode->nbytes = 1;
199
200 /* Check if there is VEX prefix or not */
201 if (insn_is_avx(insn)) {
202 insn_byte_t m, p;
203 m = insn_vex_m_bits(insn);
204 p = insn_vex_p_bits(insn);
205 insn->attr = inat_get_avx_attribute(op, m, p);
206 if (!inat_accept_vex(insn->attr) && !inat_is_group(insn->attr))
207 insn->attr = 0; /* This instruction is bad */
208 goto end; /* VEX has only 1 byte for opcode */
209 }
210
211 insn->attr = inat_get_opcode_attribute(op);
212 while (inat_is_escape(insn->attr)) {
213 /* Get escaped opcode */
214 op = get_next(insn_byte_t, insn);
215 opcode->bytes[opcode->nbytes++] = op;
216 pfx_id = insn_last_prefix_id(insn);
217 insn->attr = inat_get_escape_attribute(op, pfx_id, insn->attr);
218 }
219 if (inat_must_vex(insn->attr))
220 insn->attr = 0; /* This instruction is bad */
221end:
222 opcode->got = 1;
223
224err_out:
225 return;
226}
227
228/**
229 * insn_get_modrm - collect ModRM byte, if any
230 * @insn: &struct insn containing instruction
231 *
232 * Populates @insn->modrm and updates @insn->next_byte to point past the
233 * ModRM byte, if any. If necessary, first collects the preceding bytes
234 * (prefixes and opcode(s)). No effect if @insn->modrm.got is already 1.
235 */
236void insn_get_modrm(struct insn *insn)
237{
238 struct insn_field *modrm = &insn->modrm;
239 insn_byte_t pfx_id, mod;
240 if (modrm->got)
241 return;
242 if (!insn->opcode.got)
243 insn_get_opcode(insn);
244
245 if (inat_has_modrm(insn->attr)) {
246 mod = get_next(insn_byte_t, insn);
247 modrm->value = mod;
248 modrm->nbytes = 1;
249 if (inat_is_group(insn->attr)) {
250 pfx_id = insn_last_prefix_id(insn);
251 insn->attr = inat_get_group_attribute(mod, pfx_id,
252 insn->attr);
253 if (insn_is_avx(insn) && !inat_accept_vex(insn->attr))
254 insn->attr = 0; /* This is bad */
255 }
256 }
257
258 if (insn->x86_64 && inat_is_force64(insn->attr))
259 insn->opnd_bytes = 8;
260 modrm->got = 1;
261
262err_out:
263 return;
264}
265
266
267/**
268 * insn_rip_relative() - Does instruction use RIP-relative addressing mode?
269 * @insn: &struct insn containing instruction
270 *
271 * If necessary, first collects the instruction up to and including the
272 * ModRM byte. No effect if @insn->x86_64 is 0.
273 */
274int insn_rip_relative(struct insn *insn)
275{
276 struct insn_field *modrm = &insn->modrm;
277
278 if (!insn->x86_64)
279 return 0;
280 if (!modrm->got)
281 insn_get_modrm(insn);
282 /*
283 * For rip-relative instructions, the mod field (top 2 bits)
284 * is zero and the r/m field (bottom 3 bits) is 0x5.
285 */
286 return (modrm->nbytes && (modrm->value & 0xc7) == 0x5);
287}
288
289/**
290 * insn_get_sib() - Get the SIB byte of instruction
291 * @insn: &struct insn containing instruction
292 *
293 * If necessary, first collects the instruction up to and including the
294 * ModRM byte.
295 */
296void insn_get_sib(struct insn *insn)
297{
298 insn_byte_t modrm;
299
300 if (insn->sib.got)
301 return;
302 if (!insn->modrm.got)
303 insn_get_modrm(insn);
304 if (insn->modrm.nbytes) {
305 modrm = (insn_byte_t)insn->modrm.value;
306 if (insn->addr_bytes != 2 &&
307 X86_MODRM_MOD(modrm) != 3 && X86_MODRM_RM(modrm) == 4) {
308 insn->sib.value = get_next(insn_byte_t, insn);
309 insn->sib.nbytes = 1;
310 }
311 }
312 insn->sib.got = 1;
313
314err_out:
315 return;
316}
317
318
319/**
320 * insn_get_displacement() - Get the displacement of instruction
321 * @insn: &struct insn containing instruction
322 *
323 * If necessary, first collects the instruction up to and including the
324 * SIB byte.
325 * Displacement value is sign-expanded.
326 */
327void insn_get_displacement(struct insn *insn)
328{
329 insn_byte_t mod, rm, base;
330
331 if (insn->displacement.got)
332 return;
333 if (!insn->sib.got)
334 insn_get_sib(insn);
335 if (insn->modrm.nbytes) {
336 /*
337 * Interpreting the modrm byte:
338 * mod = 00 - no displacement fields (exceptions below)
339 * mod = 01 - 1-byte displacement field
340 * mod = 10 - displacement field is 4 bytes, or 2 bytes if
341 * address size = 2 (0x67 prefix in 32-bit mode)
342 * mod = 11 - no memory operand
343 *
344 * If address size = 2...
345 * mod = 00, r/m = 110 - displacement field is 2 bytes
346 *
347 * If address size != 2...
348 * mod != 11, r/m = 100 - SIB byte exists
349 * mod = 00, SIB base = 101 - displacement field is 4 bytes
350 * mod = 00, r/m = 101 - rip-relative addressing, displacement
351 * field is 4 bytes
352 */
353 mod = X86_MODRM_MOD(insn->modrm.value);
354 rm = X86_MODRM_RM(insn->modrm.value);
355 base = X86_SIB_BASE(insn->sib.value);
356 if (mod == 3)
357 goto out;
358 if (mod == 1) {
359 insn->displacement.value = get_next(char, insn);
360 insn->displacement.nbytes = 1;
361 } else if (insn->addr_bytes == 2) {
362 if ((mod == 0 && rm == 6) || mod == 2) {
363 insn->displacement.value =
364 get_next(short, insn);
365 insn->displacement.nbytes = 2;
366 }
367 } else {
368 if ((mod == 0 && rm == 5) || mod == 2 ||
369 (mod == 0 && base == 5)) {
370 insn->displacement.value = get_next(int, insn);
371 insn->displacement.nbytes = 4;
372 }
373 }
374 }
375out:
376 insn->displacement.got = 1;
377
378err_out:
379 return;
380}
381
382/* Decode moffset16/32/64. Return 0 if failed */
383static int __get_moffset(struct insn *insn)
384{
385 switch (insn->addr_bytes) {
386 case 2:
387 insn->moffset1.value = get_next(short, insn);
388 insn->moffset1.nbytes = 2;
389 break;
390 case 4:
391 insn->moffset1.value = get_next(int, insn);
392 insn->moffset1.nbytes = 4;
393 break;
394 case 8:
395 insn->moffset1.value = get_next(int, insn);
396 insn->moffset1.nbytes = 4;
397 insn->moffset2.value = get_next(int, insn);
398 insn->moffset2.nbytes = 4;
399 break;
400 default: /* opnd_bytes must be modified manually */
401 goto err_out;
402 }
403 insn->moffset1.got = insn->moffset2.got = 1;
404
405 return 1;
406
407err_out:
408 return 0;
409}
410
411/* Decode imm v32(Iz). Return 0 if failed */
412static int __get_immv32(struct insn *insn)
413{
414 switch (insn->opnd_bytes) {
415 case 2:
416 insn->immediate.value = get_next(short, insn);
417 insn->immediate.nbytes = 2;
418 break;
419 case 4:
420 case 8:
421 insn->immediate.value = get_next(int, insn);
422 insn->immediate.nbytes = 4;
423 break;
424 default: /* opnd_bytes must be modified manually */
425 goto err_out;
426 }
427
428 return 1;
429
430err_out:
431 return 0;
432}
433
434/* Decode imm v64(Iv/Ov), Return 0 if failed */
435static int __get_immv(struct insn *insn)
436{
437 switch (insn->opnd_bytes) {
438 case 2:
439 insn->immediate1.value = get_next(short, insn);
440 insn->immediate1.nbytes = 2;
441 break;
442 case 4:
443 insn->immediate1.value = get_next(int, insn);
444 insn->immediate1.nbytes = 4;
445 break;
446 case 8:
447 insn->immediate1.value = get_next(int, insn);
448 insn->immediate1.nbytes = 4;
449 insn->immediate2.value = get_next(int, insn);
450 insn->immediate2.nbytes = 4;
451 break;
452 default: /* opnd_bytes must be modified manually */
453 goto err_out;
454 }
455 insn->immediate1.got = insn->immediate2.got = 1;
456
457 return 1;
458err_out:
459 return 0;
460}
461
462/* Decode ptr16:16/32(Ap) */
463static int __get_immptr(struct insn *insn)
464{
465 switch (insn->opnd_bytes) {
466 case 2:
467 insn->immediate1.value = get_next(short, insn);
468 insn->immediate1.nbytes = 2;
469 break;
470 case 4:
471 insn->immediate1.value = get_next(int, insn);
472 insn->immediate1.nbytes = 4;
473 break;
474 case 8:
475 /* ptr16:64 is not exist (no segment) */
476 return 0;
477 default: /* opnd_bytes must be modified manually */
478 goto err_out;
479 }
480 insn->immediate2.value = get_next(unsigned short, insn);
481 insn->immediate2.nbytes = 2;
482 insn->immediate1.got = insn->immediate2.got = 1;
483
484 return 1;
485err_out:
486 return 0;
487}
488
489/**
490 * insn_get_immediate() - Get the immediates of instruction
491 * @insn: &struct insn containing instruction
492 *
493 * If necessary, first collects the instruction up to and including the
494 * displacement bytes.
495 * Basically, most of immediates are sign-expanded. Unsigned-value can be
496 * get by bit masking with ((1 << (nbytes * 8)) - 1)
497 */
498void insn_get_immediate(struct insn *insn)
499{
500 if (insn->immediate.got)
501 return;
502 if (!insn->displacement.got)
503 insn_get_displacement(insn);
504
505 if (inat_has_moffset(insn->attr)) {
506 if (!__get_moffset(insn))
507 goto err_out;
508 goto done;
509 }
510
511 if (!inat_has_immediate(insn->attr))
512 /* no immediates */
513 goto done;
514
515 switch (inat_immediate_size(insn->attr)) {
516 case INAT_IMM_BYTE:
517 insn->immediate.value = get_next(char, insn);
518 insn->immediate.nbytes = 1;
519 break;
520 case INAT_IMM_WORD:
521 insn->immediate.value = get_next(short, insn);
522 insn->immediate.nbytes = 2;
523 break;
524 case INAT_IMM_DWORD:
525 insn->immediate.value = get_next(int, insn);
526 insn->immediate.nbytes = 4;
527 break;
528 case INAT_IMM_QWORD:
529 insn->immediate1.value = get_next(int, insn);
530 insn->immediate1.nbytes = 4;
531 insn->immediate2.value = get_next(int, insn);
532 insn->immediate2.nbytes = 4;
533 break;
534 case INAT_IMM_PTR:
535 if (!__get_immptr(insn))
536 goto err_out;
537 break;
538 case INAT_IMM_VWORD32:
539 if (!__get_immv32(insn))
540 goto err_out;
541 break;
542 case INAT_IMM_VWORD:
543 if (!__get_immv(insn))
544 goto err_out;
545 break;
546 default:
547 /* Here, insn must have an immediate, but failed */
548 goto err_out;
549 }
550 if (inat_has_second_immediate(insn->attr)) {
551 insn->immediate2.value = get_next(char, insn);
552 insn->immediate2.nbytes = 1;
553 }
554done:
555 insn->immediate.got = 1;
556
557err_out:
558 return;
559}
560
561/**
562 * insn_get_length() - Get the length of instruction
563 * @insn: &struct insn containing instruction
564 *
565 * If necessary, first collects the instruction up to and including the
566 * immediates bytes.
567 */
568void insn_get_length(struct insn *insn)
569{
570 if (insn->length)
571 return;
572 if (!insn->immediate.got)
573 insn_get_immediate(insn);
574 insn->length = (unsigned char)((unsigned long)insn->next_byte
575 - (unsigned long)insn->kaddr);
576}