summaryrefslogtreecommitdiffstats
path: root/kernel/trace/trace_probe.c
blob: d06e67cca3e167538b7fed2dd384628efc1457a9 (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
// 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"

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")

/* 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[]"),
	/* 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_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;
}

/* 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;
}

#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, bool is_return,
			    bool is_kprobe)
{
	int ret = 0;
	unsigned long param;

	if (strcmp(arg, "retval") == 0) {
		if (is_return)
			code->op = FETCH_OP_RETVAL;
		else
			ret = -EINVAL;
	} else if (strncmp(arg, "stack", 5) == 0) {
		if (arg[5] == '\0') {
			code->op = FETCH_OP_STACKP;
		} else if (isdigit(arg[5])) {
			ret = kstrtoul(arg + 5, 10, &param);
			if (ret || (is_kprobe && param > PARAM_MAX_STACK))
				ret = -EINVAL;
			else {
				code->op = FETCH_OP_STACK;
				code->param = (unsigned int)param;
			}
		} else
			ret = -EINVAL;
	} else if (strcmp(arg, "comm") == 0) {
		code->op = FETCH_OP_COMM;
	} else
		ret = -EINVAL;

	return ret;
}

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

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

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

			ret = kstrtol(arg + 2, 0, &offset);
			if (ret)
				break;

			code->op = FETCH_OP_FOFFS;
			code->immediate = (unsigned long)offset;  // imm64?
		} else {
			/* uprobes don't support symbols */
			if (!is_kprobe)
				return -EINVAL;

			ret = traceprobe_split_symbol_offset(arg + 1, &offset);
			if (ret)
				break;

			code->op = FETCH_OP_IMM;
			code->immediate =
				(unsigned long)kallsyms_lookup_name(arg + 1);
			if (!code->immediate)
				return -ENOENT;
			code->immediate += offset;
		}
		/* These are fetching from memory */
		if (++code == end)
			return -E2BIG;
		*pcode = code;
		code->op = FETCH_OP_DEREF;
		code->offset = offset;
		break;

	case '+':	/* deref memory */
		arg++;	/* Skip '+', because kstrtol() rejects it. */
	case '-':
		tmp = strchr(arg, '(');
		if (!tmp)
			return -EINVAL;

		*tmp = '\0';
		ret = kstrtol(arg, 0, &offset);
		if (ret)
			break;

		arg = tmp + 1;
		tmp = strrchr(arg, ')');

		if (tmp) {
			const struct fetch_type *t2 = find_fetch_type(NULL);

			*tmp = '\0';
			ret = parse_probe_arg(arg, t2, &code, end, is_return,
					      is_kprobe);
			if (ret)
				break;
			if (code->op == FETCH_OP_COMM)
				return -EINVAL;
			if (++code == end)
				return -E2BIG;
			*pcode = code;

			code->op = FETCH_OP_DEREF;
			code->offset = offset;
		}
		break;
	}
	if (!ret && code->op == FETCH_OP_NOP) {
		/* Parsed, but do not find fetch method */
		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 -E2BIG;
	*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 */
int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
		struct probe_arg *parg, bool is_return, bool is_kprobe)
{
	struct fetch_insn *code, *tmp = NULL;
	const char *t;
	int ret;

	if (strlen(arg) > MAX_ARGSTR_LEN) {
		pr_info("Argument is too long.: %s\n",  arg);
		return -ENOSPC;
	}
	parg->comm = kstrdup(arg, GFP_KERNEL);
	if (!parg->comm) {
		pr_info("Failed to allocate memory for command '%s'.\n", arg);
		return -ENOMEM;
	}
	t = strchr(parg->comm, ':');
	if (t) {
		arg[t - parg->comm] = '\0';
		t++;
	}
	/*
	 * The default type of $comm should be "string", and it can't be
	 * dereferenced.
	 */
	if (!t && strcmp(arg, "$comm") == 0)
		t = "string";
	parg->type = find_fetch_type(t);
	if (!parg->type) {
		pr_info("Unsupported type: %s\n", t);
		return -EINVAL;
	}
	parg->offset = *size;
	*size += parg->type->size;

	code = tmp = kzalloc(sizeof(*code) * FETCH_INSN_MAX, GFP_KERNEL);
	if (!code)
		return -ENOMEM;
	code[FETCH_INSN_MAX - 1].op = FETCH_OP_END;

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

	/* Store operation */
	if (!strcmp(parg->type->name, "string")) {
		if (code->op != FETCH_OP_DEREF && code->op != FETCH_OP_IMM &&
		    code->op != FETCH_OP_COMM) {
			pr_info("string only accepts memory or address.\n");
			ret = -EINVAL;
			goto fail;
		}
		/* Since IMM or COMM must be the 1st insn, this is safe */
		if (code->op == FETCH_OP_IMM || code->op == FETCH_OP_COMM)
			code++;
		code->op = FETCH_OP_ST_STRING;	/* In DEREF case, replace it */
		parg->dynamic = true;
	} else if (code->op == FETCH_OP_DEREF) {
		code->op = FETCH_OP_ST_MEM;
		code->size = parg->type->size;
	} else {
		code++;
		if (code->op != FETCH_OP_NOP) {
			ret = -E2BIG;
			goto fail;
		}
		code->op = FETCH_OP_ST_RAW;
		code->size = parg->type->size;
	}
	/* Modify operation */
	if (t != NULL) {
		ret = __parse_bitfield_probe_arg(t, parg->type, &code);
		if (ret)
			goto fail;
	}
	code++;
	code->op = FETCH_OP_END;

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

fail:
	kfree(tmp);

	return ret;
}

/* Return 1 if name is reserved or already used by another argument */
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;
}

void traceprobe_free_probe_arg(struct probe_arg *arg)
{
	kfree(arg->code);
	kfree(arg->name);
	kfree(arg->comm);
}

static int __set_print_fmt(struct trace_probe *tp, char *buf, int len,
			   bool is_return)
{
	int i;
	int pos = 0;

	const char *fmt, *arg;

	if (!is_return) {
		fmt = "(%lx)";
		arg = "REC->" FIELD_STRING_IP;
	} else {
		fmt = "(%lx <- %lx)";
		arg = "REC->" FIELD_STRING_FUNC ", REC->" FIELD_STRING_RETIP;
	}

	/* When len=0, we just calculate the needed length */
#define LEN_OR_ZERO (len ? len - pos : 0)

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

	for (i = 0; i < tp->nr_args; i++) {
		pos += snprintf(buf + pos, LEN_OR_ZERO, " %s=%s",
				tp->args[i].name, tp->args[i].type->fmt);
	}

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

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

#undef LEN_OR_ZERO

	/* return the length of print_fmt */
	return pos;
}

int set_print_fmt(struct trace_probe *tp, bool is_return)
{
	int len;
	char *print_fmt;

	/* First: called with 0 length to calculate the needed length */
	len = __set_print_fmt(tp, NULL, 0, is_return);
	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, is_return);
	tp->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];

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