summaryrefslogtreecommitdiffstats
path: root/kernel/trace/trace_probe.c
blob: 80863c6508e5e94c48ce39f0746c5858663a87d0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
// SPDX-License-Identifier: GPL-2.0
/*
 * Common code for probe-based Dynamic events.
 *
 * This code was copied from kernel/trace/trace_kprobe.c written by
 * Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
 *
 * Updates to make this generic:
 * Copyright (C) IBM Corporation, 2010-2011
 * Author:     Srikar Dronamraju
 */
#define pr_fmt(fmt)	"trace_probe: " fmt

#include "trace_probe.h"

#undef C
#define C(a, b)		b

static const char *trace_probe_err_text[] = { ERRORS };

static const char *reserved_field_names[] = {
	"common_type",
	"common_flags",
	"common_preempt_count",
	"common_pid",
	"common_tgid",
	FIELD_STRING_IP,
	FIELD_STRING_RETIP,
	FIELD_STRING_FUNC,
};

/* Printing  in basic type function template */
#define DEFINE_BASIC_PRINT_TYPE_FUNC(tname, type, fmt)			\
int PRINT_TYPE_FUNC_NAME(tname)(struct trace_seq *s, void *data, void *ent)\
{									\
	trace_seq_printf(s, fmt, *(type *)data);			\
	return !trace_seq_has_overflowed(s);				\
}									\
const char PRINT_TYPE_FMT_NAME(tname)[] = fmt;

DEFINE_BASIC_PRINT_TYPE_FUNC(u8,  u8,  "%u")
DEFINE_BASIC_PRINT_TYPE_FUNC(u16, u16, "%u")
DEFINE_BASIC_PRINT_TYPE_FUNC(u32, u32, "%u")
DEFINE_BASIC_PRINT_TYPE_FUNC(u64, u64, "%Lu")
DEFINE_BASIC_PRINT_TYPE_FUNC(s8,  s8,  "%d")
DEFINE_BASIC_PRINT_TYPE_FUNC(s16, s16, "%d")
DEFINE_BASIC_PRINT_TYPE_FUNC(s32, s32, "%d")
DEFINE_BASIC_PRINT_TYPE_FUNC(s64, s64, "%Ld")
DEFINE_BASIC_PRINT_TYPE_FUNC(x8,  u8,  "0x%x")
DEFINE_BASIC_PRINT_TYPE_FUNC(x16, u16, "0x%x")
DEFINE_BASIC_PRINT_TYPE_FUNC(x32, u32, "0x%x")
DEFINE_BASIC_PRINT_TYPE_FUNC(x64, u64, "0x%Lx")

int PRINT_TYPE_FUNC_NAME(symbol)(struct trace_seq *s, void *data, void *ent)
{
	trace_seq_printf(s, "%pS", (void *)*(unsigned long *)data);
	return !trace_seq_has_overflowed(s);
}
const char PRINT_TYPE_FMT_NAME(symbol)[] = "%pS";

/* Print type function for string type */
int PRINT_TYPE_FUNC_NAME(string)(struct trace_seq *s, void *data, void *ent)
{
	int len = *(u32 *)data >> 16;

	if (!len)
		trace_seq_puts(s, "(fault)");
	else
		trace_seq_printf(s, "\"%s\"",
				 (const char *)get_loc_data(data, ent));
	return !trace_seq_has_overflowed(s);
}

const char PRINT_TYPE_FMT_NAME(string)[] = "\\\"%s\\\"";

/* Fetch type information table */
static const struct fetch_type probe_fetch_types[] = {
	/* Special types */
	__ASSIGN_FETCH_TYPE("string", string, string, sizeof(u32), 1,
			    "__data_loc char[]"),
	__ASSIGN_FETCH_TYPE("ustring", string, string, sizeof(u32), 1,
			    "__data_loc char[]"),
	/* Basic types */
	ASSIGN_FETCH_TYPE(u8,  u8,  0),
	ASSIGN_FETCH_TYPE(u16, u16, 0),
	ASSIGN_FETCH_TYPE(u32, u32, 0),
	ASSIGN_FETCH_TYPE(u64, u64, 0),
	ASSIGN_FETCH_TYPE(s8,  u8,  1),
	ASSIGN_FETCH_TYPE(s16, u16, 1),
	ASSIGN_FETCH_TYPE(s32, u32, 1),
	ASSIGN_FETCH_TYPE(s64, u64, 1),
	ASSIGN_FETCH_TYPE_ALIAS(x8,  u8,  u8,  0),
	ASSIGN_FETCH_TYPE_ALIAS(x16, u16, u16, 0),
	ASSIGN_FETCH_TYPE_ALIAS(x32, u32, u32, 0),
	ASSIGN_FETCH_TYPE_ALIAS(x64, u64, u64, 0),
	ASSIGN_FETCH_TYPE_ALIAS(symbol, ADDR_FETCH_TYPE, ADDR_FETCH_TYPE, 0),

	ASSIGN_FETCH_TYPE_END
};

static const struct fetch_type *find_fetch_type(const char *type)
{
	int i;

	if (!type)
		type = DEFAULT_FETCH_TYPE_STR;

	/* Special case: bitfield */
	if (*type == 'b') {
		unsigned long bs;

		type = strchr(type, '/');
		if (!type)
			goto fail;

		type++;
		if (kstrtoul(type, 0, &bs))
			goto fail;

		switch (bs) {
		case 8:
			return find_fetch_type("u8");
		case 16:
			return find_fetch_type("u16");
		case 32:
			return find_fetch_type("u32");
		case 64:
			return find_fetch_type("u64");
		default:
			goto fail;
		}
	}

	for (i = 0; probe_fetch_types[i].name; i++) {
		if (strcmp(type, probe_fetch_types[i].name) == 0)
			return &probe_fetch_types[i];
	}

fail:
	return NULL;
}

static struct trace_probe_log trace_probe_log;

void trace_probe_log_init(const char *subsystem, int argc, const char **argv)
{
	trace_probe_log.subsystem = subsystem;
	trace_probe_log.argc = argc;
	trace_probe_log.argv = argv;
	trace_probe_log.index = 0;
}

void trace_probe_log_clear(void)
{
	memset(&trace_probe_log, 0, sizeof(trace_probe_log));
}

void trace_probe_log_set_index(int index)
{
	trace_probe_log.index = index;
}

void __trace_probe_log_err(int offset, int err_type)
{
	char *command, *p;
	int i, len = 0, pos = 0;

	if (!trace_probe_log.argv)
		return;

	/* Recalculate the length and allocate buffer */
	for (i = 0; i < trace_probe_log.argc; i++) {
		if (i == trace_probe_log.index)
			pos = len;
		len += strlen(trace_probe_log.argv[i]) + 1;
	}
	command = kzalloc(len, GFP_KERNEL);
	if (!command)
		return;

	if (trace_probe_log.index >= trace_probe_log.argc) {
		/**
		 * Set the error position is next to the last arg + space.
		 * Note that len includes the terminal null and the cursor
		 * appears at pos + 1.
		 */
		pos = len;
		offset = 0;
	}

	/* And make a command string from argv array */
	p = command;
	for (i = 0; i < trace_probe_log.argc; i++) {
		len = strlen(trace_probe_log.argv[i]);
		strcpy(p, trace_probe_log.argv[i]);
		p[len] = ' ';
		p += len + 1;
	}
	*(p - 1) = '\0';

	tracing_log_err(NULL, trace_probe_log.subsystem, command,
			trace_probe_err_text, err_type, pos + offset);

	kfree(command);
}

/* Split symbol and offset. */
int traceprobe_split_symbol_offset(char *symbol, long *offset)
{
	char *tmp;
	int ret;

	if (!offset)
		return -EINVAL;

	tmp = strpbrk(symbol, "+-");
	if (tmp) {
		ret = kstrtol(tmp, 0, offset);
		if (ret)
			return ret;
		*tmp = '\0';
	} else
		*offset = 0;

	return 0;
}

/* @buf must has MAX_EVENT_NAME_LEN size */
int traceprobe_parse_event_name(const char **pevent, const char **pgroup,
				char *buf, int offset)
{
	const char *slash, *event = *pevent;
	int len;

	slash = strchr(event, '/');
	if (!slash)
		slash = strchr(event, '.');

	if (slash) {
		if (slash == event) {
			trace_probe_log_err(offset, NO_GROUP_NAME);
			return -EINVAL;
		}
		if (slash - event + 1 > MAX_EVENT_NAME_LEN) {
			trace_probe_log_err(offset, GROUP_TOO_LONG);
			return -EINVAL;
		}
		strlcpy(buf, event, slash - event + 1);
		if (!is_good_name(buf)) {
			trace_probe_log_err(offset, BAD_GROUP_NAME);
			return -EINVAL;
		}
		*pgroup = buf;
		*pevent = slash + 1;
		offset += slash - event + 1;
		event = *pevent;
	}
	len = strlen(event);
	if (len == 0) {
		trace_probe_log_err(offset, NO_EVENT_NAME);
		return -EINVAL;
	} else if (len > MAX_EVENT_NAME_LEN) {
		trace_probe_log_err(offset, EVENT_TOO_LONG);
		return -EINVAL;
	}
	if (!is_good_name(event)) {
		trace_probe_log_err(offset, BAD_EVENT_NAME);
		return -EINVAL;
	}
	return 0;
}

#define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))

static int parse_probe_vars(char *arg, const struct fetch_type *t,
			struct fetch_insn *code, unsigned int flags, int offs)
{
	unsigned long param;
	int ret = 0;
	int len;

	if (strcmp(arg, "retval") == 0) {
		if (flags & TPARG_FL_RETURN) {
			code->op = FETCH_OP_RETVAL;
		} else {
			trace_probe_log_err(offs, RETVAL_ON_PROBE);
			ret = -EINVAL;
		}
	} else if ((len = str_has_prefix(arg, "stack"))) {
		if (arg[len] == '\0') {
			code->op = FETCH_OP_STACKP;
		} else if (isdigit(arg[len])) {
			ret = kstrtoul(arg + len, 10, &param);
			if (ret) {
				goto inval_var;
			} else if ((flags & TPARG_FL_KERNEL) &&
				    param > PARAM_MAX_STACK) {
				trace_probe_log_err(offs, BAD_STACK_NUM);
				ret = -EINVAL;
			} else {
				code->op = FETCH_OP_STACK;
				code->param = (unsigned int)param;
			}
		} else
			goto inval_var;
	} else if (strcmp(arg, "comm") == 0) {
		code->op = FETCH_OP_COMM;
#ifdef CONFIG_HAVE_FUNCTION_ARG_ACCESS_API
	} else if (((flags & TPARG_FL_MASK) ==
		    (TPARG_FL_KERNEL | TPARG_FL_FENTRY)) &&
		   (len = str_has_prefix(arg, "arg"))) {
		ret = kstrtoul(arg + len, 10, &param);
		if (ret) {
			goto inval_var;
		} else if (!param || param > PARAM_MAX_STACK) {
			trace_probe_log_err(offs, BAD_ARG_NUM);
			return -EINVAL;
		}
		code->op = FETCH_OP_ARG;
		code->param = (unsigned int)param - 1;
#endif
	} else if (flags & TPARG_FL_TPOINT) {
		if (code->data)
			return -EFAULT;
		code->data = kstrdup(arg, GFP_KERNEL);
		if (!code->data)
			return -ENOMEM;
		code->op = FETCH_OP_TP_ARG;
	} else
		goto inval_var;

	return ret;

inval_var:
	trace_probe_log_err(offs, BAD_VAR);
	return -EINVAL;
}

static int str_to_immediate(char *str, unsigned long *imm)
{
	if (isdigit(str[0]))
		return kstrtoul(str, 0, imm);
	else if (str[0] == '-')
		return kstrtol(str, 0, (long *)imm);
	else if (str[0] == '+')
		return kstrtol(str + 1, 0, (long *)imm);
	return -EINVAL;
}

static int __parse_imm_string(char *str, char **pbuf, int offs)
{
	size_t len = strlen(str);

	if (str[len - 1] != '"') {
		trace_probe_log_err(offs + len, IMMSTR_NO_CLOSE);
		return -EINVAL;
	}
	*pbuf = kstrndup(str, len - 1, GFP_KERNEL);
	if (!*pbuf)
		return -ENOMEM;
	return 0;
}

/* Recursive argument parser */
static int
parse_probe_arg(char *arg, const struct fetch_type *type,
		struct fetch_insn **pcode, struct fetch_insn *end,
		unsigned int flags, int offs)
{
	struct fetch_insn *code = *pcode;
	unsigned long param;
	int deref = FETCH_OP_DEREF;
	long offset = 0;
	char *tmp;
	int ret = 0;

	switch (arg[0]) {
	case '$':
		ret = parse_probe_vars(arg + 1, type, code, flags, offs);
		break;

	case '%':	/* named register */
		ret = regs_query_register_offset(arg + 1);
		if (ret >= 0) {
			code->op = FETCH_OP_REG;
			code->param = (unsigned int)ret;
			ret = 0;
		} else
			trace_probe_log_err(offs, BAD_REG_NAME);
		break;

	case '@':	/* memory, file-offset or symbol */
		if (isdigit(arg[1])) {
			ret = kstrtoul(arg + 1, 0, &param);
			if (ret) {
				trace_probe_log_err(offs, BAD_MEM_ADDR);
				break;
			}
			/* load address */
			code->op = FETCH_OP_IMM;
			code->immediate = param;
		} else if (arg[1] == '+') {
			/* kprobes don't support file offsets */
			if (flags & TPARG_FL_KERNEL) {
				trace_probe_log_err(offs, FILE_ON_KPROBE);
				return -EINVAL;
			}
			ret = kstrtol(arg + 2, 0, &offset);
			if (ret) {
				trace_probe_log_err(offs, BAD_FILE_OFFS);
				break;
			}

			code->op = FETCH_OP_FOFFS;
			code->immediate = (unsigned long)offset;  // imm64?
		} else {
			/* uprobes don't support symbols */
			if (!(flags & TPARG_FL_KERNEL)) {
				trace_probe_log_err(offs, SYM_ON_UPROBE);
				return -EINVAL;
			}
			/* Preserve symbol for updating */
			code->op = FETCH_NOP_SYMBOL;
			code->data = kstrdup(arg + 1, GFP_KERNEL);
			if (!code->data)
				return -ENOMEM;
			if (++code == end) {
				trace_probe_log_err(offs, TOO_MANY_OPS);
				return -EINVAL;
			}
			code->op = FETCH_OP_IMM;
			code->immediate = 0;
		}
		/* These are fetching from memory */
		if (++code == end) {
			trace_probe_log_err(offs, TOO_MANY_OPS);
			return -EINVAL;
		}
		*pcode = code;
		code->op = FETCH_OP_DEREF;
		code->offset = offset;
		break;

	case '+':	/* deref memory */
	case '-':
		if (arg[1] == 'u') {
			deref = FETCH_OP_UDEREF;
			arg[1] = arg[0];
			arg++;
		}
		if (arg[0] == '+')
			arg++;	/* Skip '+', because kstrtol() rejects it. */
		tmp = strchr(arg, '(');
		if (!tmp) {
			trace_probe_log_err(offs, DEREF_NEED_BRACE);
			return -EINVAL;
		}
		*tmp = '\0';
		ret = kstrtol(arg, 0, &offset);
		if (ret) {
			trace_probe_log_err(offs, BAD_DEREF_OFFS);
			break;
		}
		offs += (tmp + 1 - arg) + (arg[0] != '-' ? 1 : 0);
		arg = tmp + 1;
		tmp = strrchr(arg, ')');
		if (!tmp) {
			trace_probe_log_err(offs + strlen(arg),
					    DEREF_OPEN_BRACE);
			return -EINVAL;
		} else {
			const struct fetch_type *t2 = find_fetch_type(NULL);

			*tmp = '\0';
			ret = parse_probe_arg(arg, t2, &code, end, flags, offs);
			if (ret)
				break;
			if (code->op == FETCH_OP_COMM ||
			    code->op == FETCH_OP_DATA) {
				trace_probe_log_err(offs, COMM_CANT_DEREF);
				return -EINVAL;
			}
			if (++code == end) {
				trace_probe_log_err(offs, TOO_MANY_OPS);
				return -EINVAL;
			}
			*pcode = code;

			code->op = deref;
			code->offset = offset;
		}
		break;
	case '\\':	/* Immediate value */
		if (arg[1] == '"') {	/* Immediate string */
			ret = __parse_imm_string(arg + 2, &tmp, offs + 2);
			if (ret)
				break;
			code->op = FETCH_OP_DATA;
			code->data = tmp;
		} else {
			ret = str_to_immediate(arg + 1, &code->immediate);
			if (ret)
				trace_probe_log_err(offs + 1, BAD_IMM);
			else
				code->op = FETCH_OP_IMM;
		}
		break;
	}
	if (!ret && code->op == FETCH_OP_NOP) {
		/* Parsed, but do not find fetch method */
		trace_probe_log_err(offs, BAD_FETCH_ARG);
		ret = -EINVAL;
	}
	return ret;
}

#define BYTES_TO_BITS(nb)	((BITS_PER_LONG * (nb)) / sizeof(long))

/* Bitfield type needs to be parsed into a fetch function */
static int __parse_bitfield_probe_arg(const char *bf,
				      const struct fetch_type *t,
				      struct fetch_insn **pcode)
{
	struct fetch_insn *code = *pcode;
	unsigned long bw, bo;
	char *tail;

	if (*bf != 'b')
		return 0;

	bw = simple_strtoul(bf + 1, &tail, 0);	/* Use simple one */

	if (bw == 0 || *tail != '@')
		return -EINVAL;

	bf = tail + 1;
	bo = simple_strtoul(bf, &tail, 0);

	if (tail == bf || *tail != '/')
		return -EINVAL;
	code++;
	if (code->op != FETCH_OP_NOP)
		return -EINVAL;
	*pcode = code;

	code->op = FETCH_OP_MOD_BF;
	code->lshift = BYTES_TO_BITS(t->size) - (bw + bo);
	code->rshift = BYTES_TO_BITS(t->size) - bw;
	code->basesize = t->size;

	return (BYTES_TO_BITS(t->size) < (bw + bo)) ? -EINVAL : 0;
}

/* String length checking wrapper */
static int traceprobe_parse_probe_arg_body(const char *argv, ssize_t *size,
		struct probe_arg *parg, unsigned int flags, int offset)
{
	struct fetch_insn *code, *scode, *tmp = NULL;
	char *t, *t2, *t3;
	char *arg;
	int ret, len;

	arg = kstrdup(argv, GFP_KERNEL);
	if (!arg)
		return -ENOMEM;

	ret = -EINVAL;
	len = strlen(arg);
	if (len > MAX_ARGSTR_LEN) {
		trace_probe_log_err(offset, ARG_TOO_LONG);
		goto out;
	} else if (len == 0) {
		trace_probe_log_err(offset, NO_ARG_BODY);
		goto out;
	}

	ret = -ENOMEM;
	parg->comm = kstrdup(arg, GFP_KERNEL);
	if (!parg->comm)
		goto out;

	ret = -EINVAL;
	t = strchr(arg, ':');
	if (t) {
		*t = '\0';
		t2 = strchr(++t, '[');
		if (t2) {
			*t2++ = '\0';
			t3 = strchr(t2, ']');
			if (!t3) {
				offset += t2 + strlen(t2) - arg;
				trace_probe_log_err(offset,
						    ARRAY_NO_CLOSE);
				goto out;
			} else if (t3[1] != '\0') {
				trace_probe_log_err(offset + t3 + 1 - arg,
						    BAD_ARRAY_SUFFIX);
				goto out;
			}
			*t3 = '\0';
			if (kstrtouint(t2, 0, &parg->count) || !parg->count) {
				trace_probe_log_err(offset + t2 - arg,
						    BAD_ARRAY_NUM);
				goto out;
			}
			if (parg->count > MAX_ARRAY_LEN) {
				trace_probe_log_err(offset + t2 - arg,
						    ARRAY_TOO_BIG);
				goto out;
			}
		}
	}

	/*
	 * Since $comm and immediate string can not be dereferenced,
	 * we can find those by strcmp.
	 */
	if (strcmp(arg, "$comm") == 0 || strncmp(arg, "\\\"", 2) == 0) {
		/* The type of $comm must be "string", and not an array. */
		if (parg->count || (t && strcmp(t, "string")))
			goto out;
		parg->type = find_fetch_type("string");
	} else
		parg->type = find_fetch_type(t);
	if (!parg->type) {
		trace_probe_log_err(offset + (t ? (t - arg) : 0), BAD_TYPE);
		goto out;
	}
	parg->offset = *size;
	*size += parg->type->size * (parg->count ?: 1);

	ret = -ENOMEM;
	if (parg->count) {
		len = strlen(parg->type->fmttype) + 6;
		parg->fmt = kmalloc(len, GFP_KERNEL);
		if (!parg->fmt)
			goto out;
		snprintf(parg->fmt, len, "%s[%d]", parg->type->fmttype,
			 parg->count);
	}

	code = tmp = kcalloc(FETCH_INSN_MAX, sizeof(*code), GFP_KERNEL);
	if (!code)
		goto out;
	code[FETCH_INSN_MAX - 1].op = FETCH_OP_END;

	ret = parse_probe_arg(arg, parg->type, &code, &code[FETCH_INSN_MAX - 1],
			      flags, offset);
	if (ret)
		goto fail;

	ret = -EINVAL;
	/* Store operation */
	if (!strcmp(parg->type->name, "string") ||
	    !strcmp(parg->type->name, "ustring")) {
		if (code->op != FETCH_OP_DEREF && code->op != FETCH_OP_UDEREF &&
		    code->op != FETCH_OP_IMM && code->op != FETCH_OP_COMM &&
		    code->op != FETCH_OP_DATA && code->op != FETCH_OP_TP_ARG) {
			trace_probe_log_err(offset + (t ? (t - arg) : 0),
					    BAD_STRING);
			goto fail;
		}
		if ((code->op == FETCH_OP_IMM || code->op == FETCH_OP_COMM ||
		     code->op == FETCH_OP_DATA) || code->op == FETCH_OP_TP_ARG ||
		     parg->count) {
			/*
			 * IMM, DATA and COMM is pointing actual address, those
			 * must be kept, and if parg->count != 0, this is an
			 * array of string pointers instead of string address
			 * itself.
			 */
			code++;
			if (code->op != FETCH_OP_NOP) {
				trace_probe_log_err(offset, TOO_MANY_OPS);
				goto fail;
			}
		}
		/* If op == DEREF, replace it with STRING */
		if (!strcmp(parg->type->name, "ustring") ||
		    code->op == FETCH_OP_UDEREF)
			code->op = FETCH_OP_ST_USTRING;
		else
			code->op = FETCH_OP_ST_STRING;
		code->size = parg->type->size;
		parg->dynamic = true;
	} else if (code->op == FETCH_OP_DEREF) {
		code->op = FETCH_OP_ST_MEM;
		code->size = parg->type->size;
	} else if (code->op == FETCH_OP_UDEREF) {
		code->op = FETCH_OP_ST_UMEM;
		code->size = parg->type->size;
	} else {
		code++;
		if (code->op != FETCH_OP_NOP) {
			trace_probe_log_err(offset, TOO_MANY_OPS);
			goto fail;
		}
		code->op = FETCH_OP_ST_RAW;
		code->size = parg->type->size;
	}
	scode = code;
	/* Modify operation */
	if (t != NULL) {
		ret = __parse_bitfield_probe_arg(t, parg->type, &code);
		if (ret) {
			trace_probe_log_err(offset + t - arg, BAD_BITFIELD);
			goto fail;
		}
	}
	ret = -EINVAL;
	/* Loop(Array) operation */
	if (parg->count) {
		if (scode->op != FETCH_OP_ST_MEM &&
		    scode->op != FETCH_OP_ST_STRING &&
		    scode->op != FETCH_OP_ST_USTRING) {
			trace_probe_log_err(offset + (t ? (t - arg) : 0),
					    BAD_STRING);
			goto fail;
		}
		code++;
		if (code->op != FETCH_OP_NOP) {
			trace_probe_log_err(offset, TOO_MANY_OPS);
			goto fail;
		}
		code->op = FETCH_OP_LP_ARRAY;
		code->param = parg->count;
	}
	code++;
	code->op = FETCH_OP_END;

	ret = 0;
	/* Shrink down the code buffer */
	parg->code = kcalloc(code - tmp + 1, sizeof(*code), GFP_KERNEL);
	if (!parg->code)
		ret = -ENOMEM;
	else
		memcpy(parg->code, tmp, sizeof(*code) * (code - tmp + 1));

fail:
	if (ret) {
		for (code = tmp; code < tmp + FETCH_INSN_MAX; code++)
			if (code->op == FETCH_NOP_SYMBOL ||
			    code->op == FETCH_OP_DATA)
				kfree(code->data);
	}
	kfree(tmp);
out:
	kfree(arg);

	return ret;
}

/* Return 1 if name is reserved or already used by another argument */
static int traceprobe_conflict_field_name(const char *name,
					  struct probe_arg *args, int narg)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(reserved_field_names); i++)
		if (strcmp(reserved_field_names[i], name) == 0)
			return 1;

	for (i = 0; i < narg; i++)
		if (strcmp(args[i].name, name) == 0)
			return 1;

	return 0;
}

int traceprobe_parse_probe_arg(struct trace_probe *tp, int i, const char *arg,
				unsigned int flags)
{
	struct probe_arg *parg = &tp->args[i];
	const char *body;

	/* Increment count for freeing args in error case */
	tp->nr_args++;

	body = strchr(arg, '=');
	if (body) {
		if (body - arg > MAX_ARG_NAME_LEN) {
			trace_probe_log_err(0, ARG_NAME_TOO_LONG);
			return -EINVAL;
		} else if (body == arg) {
			trace_probe_log_err(0, NO_ARG_NAME);
			return -EINVAL;
		}
		parg->name = kmemdup_nul(arg, body - arg, GFP_KERNEL);
		body++;
	} else {
		/* If argument name is omitted, set "argN" */
		parg->name = kasprintf(GFP_KERNEL, "arg%d", i + 1);
		body = arg;
	}
	if (!parg->name)
		return -ENOMEM;

	if (!is_good_name(parg->name)) {
		trace_probe_log_err(0, BAD_ARG_NAME);
		return -EINVAL;
	}
	if (traceprobe_conflict_field_name(parg->name, tp->args, i)) {
		trace_probe_log_err(0, USED_ARG_NAME);
		return -EINVAL;
	}
	/* Parse fetch argument */
	return traceprobe_parse_probe_arg_body(body, &tp->size, parg, flags,
					       body - arg);
}

void traceprobe_free_probe_arg(struct probe_arg *arg)
{
	struct fetch_insn *code = arg->code;

	while (code && code->op != FETCH_OP_END) {
		if (code->op == FETCH_NOP_SYMBOL ||
		    code->op == FETCH_OP_DATA)
			kfree(code->data);
		code++;
	}
	kfree(arg->code);
	kfree(arg->name);
	kfree(arg->comm);
	kfree(arg->fmt);
}

int traceprobe_update_arg(struct probe_arg *arg)
{
	struct fetch_insn *code = arg->code;
	long offset;
	char *tmp;
	char c;
	int ret = 0;

	while (code && code->op != FETCH_OP_END) {
		if (code->op == FETCH_NOP_SYMBOL) {
			if (code[1].op != FETCH_OP_IMM)
				return -EINVAL;

			tmp = strpbrk(code->data, "+-");
			if (tmp)
				c = *tmp;
			ret = traceprobe_split_symbol_offset(code->data,
							     &offset);
			if (ret)
				return ret;

			code[1].immediate =
				(unsigned long)kallsyms_lookup_name(code->data);
			if (tmp)
				*tmp = c;
			if (!code[1].immediate)
				return -ENOENT;
			code[1].immediate += offset;
		}
		code++;
	}
	return 0;
}

/* When len=0, we just calculate the needed length */
#define LEN_OR_ZERO (len ? len - pos : 0)
static int __set_print_fmt(struct trace_probe *tp, char *buf, int len,
			   enum probe_print_type ptype)
{
	struct probe_arg *parg;
	int i, j;
	int pos = 0;
	const char *fmt, *arg;

	switch (ptype) {
	case PROBE_PRINT_NORMAL:
		fmt = "(%lx)";
		arg = ", REC->" FIELD_STRING_IP;
		break;
	case PROBE_PRINT_RETURN:
		fmt = "(%lx <- %lx)";
		arg = ", REC->" FIELD_STRING_FUNC ", REC->" FIELD_STRING_RETIP;
		break;
	case PROBE_PRINT_EVENT:
		fmt = "";
		arg = "";
		break;
	default:
		WARN_ON_ONCE(1);
		return 0;
	}

	pos += snprintf(buf + pos, LEN_OR_ZERO, "\"%s", fmt);

	for (i = 0; i < tp->nr_args; i++) {
		parg = tp->args + i;
		pos += snprintf(buf + pos, LEN_OR_ZERO, " %s=", parg->name);
		if (parg->count) {
			pos += snprintf(buf + pos, LEN_OR_ZERO, "{%s",
					parg->type->fmt);
			for (j = 1; j < parg->count; j++)
				pos += snprintf(buf + pos, LEN_OR_ZERO, ",%s",
						parg->type->fmt);
			pos += snprintf(buf + pos, LEN_OR_ZERO, "}");
		} else
			pos += snprintf(buf + pos, LEN_OR_ZERO, "%s",
					parg->type->fmt);
	}

	pos += snprintf(buf + pos, LEN_OR_ZERO, "\"%s", arg);

	for (i = 0; i < tp->nr_args; i++) {
		parg = tp->args + i;
		if (parg->count) {
			if ((strcmp(parg->type->name, "string") == 0) ||
			    (strcmp(parg->type->name, "ustring") == 0))
				fmt = ", __get_str(%s[%d])";
			else
				fmt = ", REC->%s[%d]";
			for (j = 0; j < parg->count; j++)
				pos += snprintf(buf + pos, LEN_OR_ZERO,
						fmt, parg->name, j);
		} else {
			if ((strcmp(parg->type->name, "string") == 0) ||
			    (strcmp(parg->type->name, "ustring") == 0))
				fmt = ", __get_str(%s)";
			else
				fmt = ", REC->%s";
			pos += snprintf(buf + pos, LEN_OR_ZERO,
					fmt, parg->name);
		}
	}

	/* return the length of print_fmt */
	return pos;
}
#undef LEN_OR_ZERO

int traceprobe_set_print_fmt(struct trace_probe *tp, enum probe_print_type ptype)
{
	struct trace_event_call *call = trace_probe_event_call(tp);
	int len;
	char *print_fmt;

	/* First: called with 0 length to calculate the needed length */
	len = __set_print_fmt(tp, NULL, 0, ptype);
	print_fmt = kmalloc(len + 1, GFP_KERNEL);
	if (!print_fmt)
		return -ENOMEM;

	/* Second: actually write the @print_fmt */
	__set_print_fmt(tp, print_fmt, len + 1, ptype);
	call->print_fmt = print_fmt;

	return 0;
}

int traceprobe_define_arg_fields(struct trace_event_call *event_call,
				 size_t offset, struct trace_probe *tp)
{
	int ret, i;

	/* Set argument names as fields */
	for (i = 0; i < tp->nr_args; i++) {
		struct probe_arg *parg = &tp->args[i];
		const char *fmt = parg->type->fmttype;
		int size = parg->type->size;

		if (parg->fmt)
			fmt = parg->fmt;
		if (parg->count)
			size *= parg->count;
		ret = trace_define_field(event_call, fmt, parg->name,
					 offset + parg->offset, size,
					 parg->type->is_signed,
					 FILTER_OTHER);
		if (ret)
			return ret;
	}
	return 0;
}

static void trace_probe_event_free(struct trace_probe_event *tpe)
{
	kfree(tpe->class.system);
	kfree(tpe->call.name);
	kfree(tpe->call.print_fmt);
	kfree(tpe);
}

int trace_probe_append(struct trace_probe *tp, struct trace_probe *to)
{
	if (trace_probe_has_sibling(tp))
		return -EBUSY;

	list_del_init(&tp->list);
	trace_probe_event_free(tp->event);

	tp->event = to->event;
	list_add_tail(&tp->list, trace_probe_probe_list(to));

	return 0;
}

void trace_probe_unlink(struct trace_probe *tp)
{
	list_del_init(&tp->list);
	if (list_empty(trace_probe_probe_list(tp)))
		trace_probe_event_free(tp->event);
	tp->event = NULL;
}

void trace_probe_cleanup(struct trace_probe *tp)
{
	int i;

	for (i = 0; i < tp->nr_args; i++)
		traceprobe_free_probe_arg(&tp->args[i]);

	if (tp->event)
		trace_probe_unlink(tp);
}

int trace_probe_init(struct trace_probe *tp, const char *event,
		     const char *group, bool alloc_filter)
{
	struct trace_event_call *call;
	size_t size = sizeof(struct trace_probe_event);
	int ret = 0;

	if (!event || !group)
		return -EINVAL;

	if (alloc_filter)
		size += sizeof(struct trace_uprobe_filter);

	tp->event = kzalloc(size, GFP_KERNEL);
	if (!tp->event)
		return -ENOMEM;

	INIT_LIST_HEAD(&tp->event->files);
	INIT_LIST_HEAD(&tp->event->class.fields);
	INIT_LIST_HEAD(&tp->event->probes);
	INIT_LIST_HEAD(&tp->list);
	list_add(&tp->list, &tp->event->probes);

	call = trace_probe_event_call(tp);
	call->class = &tp->event->class;
	call->name = kstrdup(event, GFP_KERNEL);
	if (!call->name) {
		ret = -ENOMEM;
		goto error;
	}

	tp->event->class.system = kstrdup(group, GFP_KERNEL);
	if (!tp->event->class.system) {
		ret = -ENOMEM;
		goto error;
	}

	return 0;

error:
	trace_probe_cleanup(tp);
	return ret;
}

static struct trace_event_call *
find_trace_event_call(const char *system, const char *event_name)
{
	struct trace_event_call *tp_event;
	const char *name;

	list_for_each_entry(tp_event, &ftrace_events, list) {
		if (!tp_event->class->system ||
		    strcmp(system, tp_event->class->system))
			continue;
		name = trace_event_name(tp_event);
		if (!name || strcmp(event_name, name))
			continue;
		return tp_event;
	}

	return NULL;
}

int trace_probe_register_event_call(struct trace_probe *tp)
{
	struct trace_event_call *call = trace_probe_event_call(tp);
	int ret;

	lockdep_assert_held(&event_mutex);

	if (find_trace_event_call(trace_probe_group_name(tp),
				  trace_probe_name(tp)))
		return -EEXIST;

	ret = register_trace_event(&call->event);
	if (!ret)
		return -ENODEV;

	ret = trace_add_event_call(call);
	if (ret)
		unregister_trace_event(&call->event);

	return ret;
}

int trace_probe_add_file(struct trace_probe *tp, struct trace_event_file *file)
{
	struct event_file_link *link;

	link = kmalloc(sizeof(*link), GFP_KERNEL);
	if (!link)
		return -ENOMEM;

	link->file = file;
	INIT_LIST_HEAD(&link->list);
	list_add_tail_rcu(&link->list, &tp->event->files);
	trace_probe_set_flag(tp, TP_FLAG_TRACE);
	return 0;
}

struct event_file_link *trace_probe_get_file_link(struct trace_probe *tp,
						  struct trace_event_file *file)
{
	struct event_file_link *link;

	trace_probe_for_each_link(link, tp) {
		if (link->file == file)
			return link;
	}

	return NULL;
}

int trace_probe_remove_file(struct trace_probe *tp,
			    struct trace_event_file *file)
{
	struct event_file_link *link;

	link = trace_probe_get_file_link(tp, file);
	if (!link)
		return -ENOENT;

	list_del_rcu(&link->list);
	kvfree_rcu(link);

	if (list_empty(&tp->event->files))
		trace_probe_clear_flag(tp, TP_FLAG_TRACE);

	return 0;
}

/*
 * Return the smallest index of different type argument (start from 1).
 * If all argument types and name are same, return 0.
 */
int trace_probe_compare_arg_type(struct trace_probe *a, struct trace_probe *b)
{
	int i;

	/* In case of more arguments */
	if (a->nr_args < b->nr_args)
		return a->nr_args + 1;
	if (a->nr_args > b->nr_args)
		return b->nr_args + 1;

	for (i = 0; i < a->nr_args; i++) {
		if ((b->nr_args <= i) ||
		    ((a->args[i].type != b->args[i].type) ||
		     (a->args[i].count != b->args[i].count) ||
		     strcmp(a->args[i].name, b->args[i].name)))
			return i + 1;
	}

	return 0;
}

bool trace_probe_match_command_args(struct trace_probe *tp,
				    int argc, const char **argv)
{
	char buf[MAX_ARGSTR_LEN + 1];
	int i;

	if (tp->nr_args < argc)
		return false;

	for (i = 0; i < argc; i++) {
		snprintf(buf, sizeof(buf), "%s=%s",
			 tp->args[i].name, tp->args[i].comm);
		if (strcmp(buf, argv[i]))
			return false;
	}
	return true;
}

int trace_probe_create(const char *raw_command, int (*createfn)(int, const char **))
{
	int argc = 0, ret = 0;
	char **argv;

	argv = argv_split(GFP_KERNEL, raw_command, &argc);
	if (!argv)
		return -ENOMEM;

	if (argc)
		ret = createfn(argc, (const char **)argv);

	argv_free(argv);

	return ret;
}