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2024-01-05 071106ecf68c401173c58808b1cf5f68cc50d390 
 kernel/arch/x86/lib/insn.c
....@@ -1,19 +1,6 @@
1
+// SPDX-License-Identifier: GPL-2.0-or-later
12 /*
23  * 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.
174  *
185  * Copyright (C) IBM Corporation, 2002, 2004, 2009
196  */
....@@ -23,8 +10,13 @@
2310 #else
2411 #include <string.h>
2512 #endif
26
-#include <asm/inat.h>
27
-#include <asm/insn.h>
13
+#include <asm/inat.h> /*__ignore_sync_check__ */
14
+#include <asm/insn.h> /* __ignore_sync_check__ */
15
+
16
+#include <linux/errno.h>
17
+#include <linux/kconfig.h>
18
+
19
+#include <asm/emulate_prefix.h> /* __ignore_sync_check__ */
2820 
2921 /* Verify next sizeof(t) bytes can be on the same instruction */
3022 #define validate_next(t, insn, n)	\
....@@ -71,6 +63,36 @@
7163 		insn->addr_bytes = 4;
7264 }
7365 
66
+static const insn_byte_t xen_prefix[] = { __XEN_EMULATE_PREFIX };
67
+static const insn_byte_t kvm_prefix[] = { __KVM_EMULATE_PREFIX };
68
+
69
+static int __insn_get_emulate_prefix(struct insn *insn,
70
+				     const insn_byte_t *prefix, size_t len)
71
+{
72
+	size_t i;
73
+
74
+	for (i = 0; i < len; i++) {
75
+		if (peek_nbyte_next(insn_byte_t, insn, i) != prefix[i])
76
+			goto err_out;
77
+	}
78
+
79
+	insn->emulate_prefix_size = len;
80
+	insn->next_byte += len;
81
+
82
+	return 1;
83
+
84
+err_out:
85
+	return 0;
86
+}
87
+
88
+static void insn_get_emulate_prefix(struct insn *insn)
89
+{
90
+	if (__insn_get_emulate_prefix(insn, xen_prefix, sizeof(xen_prefix)))
91
+		return;
92
+
93
+	__insn_get_emulate_prefix(insn, kvm_prefix, sizeof(kvm_prefix));
94
+}
95
+
7496 /**
7597  * insn_get_prefixes - scan x86 instruction prefix bytes
7698  * @insn:	&struct insn containing instruction
....@@ -78,8 +100,12 @@
78100  * Populates the @insn->prefixes bitmap, and updates @insn->next_byte
79101  * to point to the (first) opcode.  No effect if @insn->prefixes.got
80102  * is already set.
103
+ *
104
+ * * Returns:
105
+ * 0:  on success
106
+ * < 0: on error
81107  */
82
-void insn_get_prefixes(struct insn *insn)
108
+int insn_get_prefixes(struct insn *insn)
83109 {
84110 	struct insn_field *prefixes = &insn->prefixes;
85111 	insn_attr_t attr;
....@@ -87,7 +113,9 @@
87113 	int i, nb;
88114 
89115 	if (prefixes->got)
90
-		return;
116
+		return 0;
117
+
118
+	insn_get_emulate_prefix(insn);
91119 
92120 	nb = 0;
93121 	lb = 0;
....@@ -196,8 +224,10 @@
196224 
197225 	prefixes->got = 1;
198226 
227
+	return 0;
228
+
199229 err_out:
200
-	return;
230
+	return -ENODATA;
201231 }
202232 
203233 /**
....@@ -209,16 +239,25 @@
209239  * If necessary, first collects any preceding (prefix) bytes.
210240  * Sets @insn->opcode.value = opcode1.  No effect if @insn->opcode.got
211241  * is already 1.
242
+ *
243
+ * Returns:
244
+ * 0:  on success
245
+ * < 0: on error
212246  */
213
-void insn_get_opcode(struct insn *insn)
247
+int insn_get_opcode(struct insn *insn)
214248 {
215249 	struct insn_field *opcode = &insn->opcode;
250
+	int pfx_id, ret;
216251 	insn_byte_t op;
217
-	int pfx_id;
252
+
218253 	if (opcode->got)
219
-		return;
220
-	if (!insn->prefixes.got)
221
-		insn_get_prefixes(insn);
254
+		return 0;
255
+
256
+	if (!insn->prefixes.got) {
257
+		ret = insn_get_prefixes(insn);
258
+		if (ret)
259
+			return ret;
260
+	}
222261 
223262 	/* Get first opcode */
224263 	op = get_next(insn_byte_t, insn);
....@@ -233,9 +272,13 @@
233272 		insn->attr = inat_get_avx_attribute(op, m, p);
234273 		if ((inat_must_evex(insn->attr) && !insn_is_evex(insn)) ||
235274 		    (!inat_accept_vex(insn->attr) &&
236
-		     !inat_is_group(insn->attr)))
237
-			insn->attr = 0;	/* This instruction is bad */
238
-		goto end;	/* VEX has only 1 byte for opcode */
275
+		     !inat_is_group(insn->attr))) {
276
+			/* This instruction is bad */
277
+			insn->attr = 0;
278
+			return -EINVAL;
279
+		}
280
+		/* VEX has only 1 byte for opcode */
281
+		goto end;
239282 	}
240283 
241284 	insn->attr = inat_get_opcode_attribute(op);
....@@ -246,13 +289,18 @@
246289 		pfx_id = insn_last_prefix_id(insn);
247290 		insn->attr = inat_get_escape_attribute(op, pfx_id, insn->attr);
248291 	}
249
-	if (inat_must_vex(insn->attr))
250
-		insn->attr = 0;	/* This instruction is bad */
292
+
293
+	if (inat_must_vex(insn->attr)) {
294
+		/* This instruction is bad */
295
+		insn->attr = 0;
296
+		return -EINVAL;
297
+	}
251298 end:
252299 	opcode->got = 1;
300
+	return 0;
253301 
254302 err_out:
255
-	return;
303
+	return -ENODATA;
256304 }
257305 
258306 /**
....@@ -262,15 +310,25 @@
262310  * Populates @insn->modrm and updates @insn->next_byte to point past the
263311  * ModRM byte, if any.  If necessary, first collects the preceding bytes
264312  * (prefixes and opcode(s)).  No effect if @insn->modrm.got is already 1.
313
+ *
314
+ * Returns:
315
+ * 0:  on success
316
+ * < 0: on error
265317  */
266
-void insn_get_modrm(struct insn *insn)
318
+int insn_get_modrm(struct insn *insn)
267319 {
268320 	struct insn_field *modrm = &insn->modrm;
269321 	insn_byte_t pfx_id, mod;
322
+	int ret;
323
+
270324 	if (modrm->got)
271
-		return;
272
-	if (!insn->opcode.got)
273
-		insn_get_opcode(insn);
325
+		return 0;
326
+
327
+	if (!insn->opcode.got) {
328
+		ret = insn_get_opcode(insn);
329
+		if (ret)
330
+			return ret;
331
+	}
274332 
275333 	if (inat_has_modrm(insn->attr)) {
276334 		mod = get_next(insn_byte_t, insn);
....@@ -280,17 +338,22 @@
280338 			pfx_id = insn_last_prefix_id(insn);
281339 			insn->attr = inat_get_group_attribute(mod, pfx_id,
282340 							      insn->attr);
283
-			if (insn_is_avx(insn) && !inat_accept_vex(insn->attr))
284
-				insn->attr = 0;	/* This is bad */
341
+			if (insn_is_avx(insn) && !inat_accept_vex(insn->attr)) {
342
+				/* Bad insn */
343
+				insn->attr = 0;
344
+				return -EINVAL;
345
+			}
285346 		}
286347 	}
287348 
288349 	if (insn->x86_64 && inat_is_force64(insn->attr))
289350 		insn->opnd_bytes = 8;
351
+
290352 	modrm->got = 1;
353
+	return 0;
291354 
292355 err_out:
293
-	return;
356
+	return -ENODATA;
294357 }
295358 
296359 
....@@ -304,11 +367,16 @@
304367 int insn_rip_relative(struct insn *insn)
305368 {
306369 	struct insn_field *modrm = &insn->modrm;
370
+	int ret;
307371 
308372 	if (!insn->x86_64)
309373 		return 0;
310
-	if (!modrm->got)
311
-		insn_get_modrm(insn);
374
+
375
+	if (!modrm->got) {
376
+		ret = insn_get_modrm(insn);
377
+		if (ret)
378
+			return 0;
379
+	}
312380 	/*
313381 	 * For rip-relative instructions, the mod field (top 2 bits)
314382 	 * is zero and the r/m field (bottom 3 bits) is 0x5.
....@@ -322,15 +390,25 @@
322390  *
323391  * If necessary, first collects the instruction up to and including the
324392  * ModRM byte.
393
+ *
394
+ * Returns:
395
+ * 0: if decoding succeeded
396
+ * < 0: otherwise.
325397  */
326
-void insn_get_sib(struct insn *insn)
398
+int insn_get_sib(struct insn *insn)
327399 {
328400 	insn_byte_t modrm;
401
+	int ret;
329402 
330403 	if (insn->sib.got)
331
-		return;
332
-	if (!insn->modrm.got)
333
-		insn_get_modrm(insn);
404
+		return 0;
405
+
406
+	if (!insn->modrm.got) {
407
+		ret = insn_get_modrm(insn);
408
+		if (ret)
409
+			return ret;
410
+	}
411
+
334412 	if (insn->modrm.nbytes) {
335413 		modrm = (insn_byte_t)insn->modrm.value;
336414 		if (insn->addr_bytes != 2 &&
....@@ -341,8 +419,10 @@
341419 	}
342420 	insn->sib.got = 1;
343421 
422
+	return 0;
423
+
344424 err_out:
345
-	return;
425
+	return -ENODATA;
346426 }
347427 
348428 
....@@ -353,15 +433,25 @@
353433  * If necessary, first collects the instruction up to and including the
354434  * SIB byte.
355435  * Displacement value is sign-expanded.
436
+ *
437
+ * * Returns:
438
+ * 0: if decoding succeeded
439
+ * < 0: otherwise.
356440  */
357
-void insn_get_displacement(struct insn *insn)
441
+int insn_get_displacement(struct insn *insn)
358442 {
359443 	insn_byte_t mod, rm, base;
444
+	int ret;
360445 
361446 	if (insn->displacement.got)
362
-		return;
363
-	if (!insn->sib.got)
364
-		insn_get_sib(insn);
447
+		return 0;
448
+
449
+	if (!insn->sib.got) {
450
+		ret = insn_get_sib(insn);
451
+		if (ret)
452
+			return ret;
453
+	}
454
+
365455 	if (insn->modrm.nbytes) {
366456 		/*
367457 		 * Interpreting the modrm byte:
....@@ -404,9 +494,10 @@
404494 	}
405495 out:
406496 	insn->displacement.got = 1;
497
+	return 0;
407498 
408499 err_out:
409
-	return;
500
+	return -ENODATA;
410501 }
411502 
412503 /* Decode moffset16/32/64. Return 0 if failed */
....@@ -517,20 +608,30 @@
517608 }
518609 
519610 /**
520
- * insn_get_immediate() - Get the immediates of instruction
611
+ * insn_get_immediate() - Get the immediate in an instruction
521612  * @insn:	&struct insn containing instruction
522613  *
523614  * If necessary, first collects the instruction up to and including the
524615  * displacement bytes.
525616  * Basically, most of immediates are sign-expanded. Unsigned-value can be
526
- * get by bit masking with ((1 << (nbytes * 8)) - 1)
617
+ * computed by bit masking with ((1 << (nbytes * 8)) - 1)
618
+ *
619
+ * Returns:
620
+ * 0:  on success
621
+ * < 0: on error
527622  */
528
-void insn_get_immediate(struct insn *insn)
623
+int insn_get_immediate(struct insn *insn)
529624 {
625
+	int ret;
626
+
530627 	if (insn->immediate.got)
531
-		return;
532
-	if (!insn->displacement.got)
533
-		insn_get_displacement(insn);
628
+		return 0;
629
+
630
+	if (!insn->displacement.got) {
631
+		ret = insn_get_displacement(insn);
632
+		if (ret)
633
+			return ret;
634
+	}
534635 
535636 	if (inat_has_moffset(insn->attr)) {
536637 		if (!__get_moffset(insn))
....@@ -583,9 +684,10 @@
583684 	}
584685 done:
585686 	insn->immediate.got = 1;
687
+	return 0;
586688 
587689 err_out:
588
-	return;
690
+	return -ENODATA;
589691 }
590692 
591693 /**
....@@ -594,13 +696,58 @@
594696  *
595697  * If necessary, first collects the instruction up to and including the
596698  * immediates bytes.
597
- */
598
-void insn_get_length(struct insn *insn)
699
+ *
700
+ * Returns:
701
+ *  - 0 on success
702
+ *  - < 0 on error
703
+*/
704
+int insn_get_length(struct insn *insn)
599705 {
706
+	int ret;
707
+
600708 	if (insn->length)
601
-		return;
602
-	if (!insn->immediate.got)
603
-		insn_get_immediate(insn);
709
+		return 0;
710
+
711
+	if (!insn->immediate.got) {
712
+		ret = insn_get_immediate(insn);
713
+		if (ret)
714
+			return ret;
715
+	}
716
+
604717 	insn->length = (unsigned char)((unsigned long)insn->next_byte
605718 				     - (unsigned long)insn->kaddr);
719
+
720
+	return 0;
721
+}
722
+
723
+/**
724
+ * insn_decode() - Decode an x86 instruction
725
+ * @insn:	&struct insn to be initialized
726
+ * @kaddr:	address (in kernel memory) of instruction (or copy thereof)
727
+ * @buf_len:	length of the insn buffer at @kaddr
728
+ * @m:		insn mode, see enum insn_mode
729
+ *
730
+ * Returns:
731
+ * 0: if decoding succeeded
732
+ * < 0: otherwise.
733
+ */
734
+int insn_decode(struct insn *insn, const void *kaddr, int buf_len, enum insn_mode m)
735
+{
736
+	int ret;
737
+
738
+/* #define INSN_MODE_KERN	-1 __ignore_sync_check__ mode is only valid in the kernel */
739
+
740
+	if (m == INSN_MODE_KERN)
741
+		insn_init(insn, kaddr, buf_len, IS_ENABLED(CONFIG_X86_64));
742
+	else
743
+		insn_init(insn, kaddr, buf_len, m == INSN_MODE_64);
744
+
745
+	ret = insn_get_length(insn);
746
+	if (ret)
747
+		return ret;
748
+
749
+	if (insn_complete(insn))
750
+		return 0;
751
+
752
+	return -EINVAL;
606753 }