summaryrefslogtreecommitdiffstats
path: root/tools/perf/builtin-probe.c
blob: 4e418afd6705fb711f1e33679d494c7710e09017 (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
/*
 * builtin-probe.c
 *
 * Builtin probe command: Set up probe events by C expression
 *
 * Written by Masami Hiramatsu <mhiramat@redhat.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 */
#define _GNU_SOURCE
#include <sys/utsname.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>

#undef _GNU_SOURCE
#include "perf.h"
#include "builtin.h"
#include "util/util.h"
#include "util/event.h"
#include "util/debug.h"
#include "util/parse-options.h"
#include "util/parse-events.h"	/* For debugfs_path */
#include "util/probe-finder.h"

/* Default vmlinux search paths */
#define NR_SEARCH_PATH 3
const char *default_search_path[NR_SEARCH_PATH] = {
"/lib/modules/%s/build/vmlinux",		/* Custom build kernel */
"/usr/lib/debug/lib/modules/%s/vmlinux",	/* Red Hat debuginfo */
"/boot/vmlinux-debug-%s",			/* Ubuntu */
};

#define MAX_PATH_LEN 256
#define MAX_PROBES 128
#define MAX_PROBE_ARGS 128
#define PERFPROBE_GROUP "probe"

/* Session management structure */
static struct {
	char *vmlinux;
	char *release;
	int need_dwarf;
	int nr_probe;
	struct probe_point probes[MAX_PROBES];
} session;

#define semantic_error(msg ...) die("Semantic error :" msg)

/* Parse probe point. Return 1 if return probe */
static void parse_probe_point(char *arg, struct probe_point *pp)
{
	char *ptr, *tmp;
	char c, nc = 0;
	/*
	 * <Syntax>
	 * perf probe SRC:LN
	 * perf probe FUNC[+OFFS|%return][@SRC]
	 */

	ptr = strpbrk(arg, ":+@%");
	if (ptr) {
		nc = *ptr;
		*ptr++ = '\0';
	}

	/* Check arg is function or file and copy it */
	if (strchr(arg, '.'))	/* File */
		pp->file = strdup(arg);
	else			/* Function */
		pp->function = strdup(arg);
	DIE_IF(pp->file == NULL && pp->function == NULL);

	/* Parse other options */
	while (ptr) {
		arg = ptr;
		c = nc;
		ptr = strpbrk(arg, ":+@%");
		if (ptr) {
			nc = *ptr;
			*ptr++ = '\0';
		}
		switch (c) {
		case ':':	/* Line number */
			pp->line = strtoul(arg, &tmp, 0);
			if (*tmp != '\0')
				semantic_error("There is non-digit charactor"
						" in line number.");
			break;
		case '+':	/* Byte offset from a symbol */
			pp->offset = strtoul(arg, &tmp, 0);
			if (*tmp != '\0')
				semantic_error("There is non-digit charactor"
						" in offset.");
			break;
		case '@':	/* File name */
			if (pp->file)
				semantic_error("SRC@SRC is not allowed.");
			pp->file = strdup(arg);
			DIE_IF(pp->file == NULL);
			if (ptr)
				semantic_error("@SRC must be the last "
					       "option.");
			break;
		case '%':	/* Probe places */
			if (strcmp(arg, "return") == 0) {
				pp->retprobe = 1;
			} else	/* Others not supported yet */
				semantic_error("%%%s is not supported.", arg);
			break;
		default:
			DIE_IF("Program has a bug.");
			break;
		}
	}

	/* Exclusion check */
	if (pp->line && pp->offset)
		semantic_error("Offset can't be used with line number.");
	if (!pp->line && pp->file && !pp->function)
		semantic_error("File always requires line number.");
	if (pp->offset && !pp->function)
		semantic_error("Offset requires an entry function.");
	if (pp->retprobe && !pp->function)
		semantic_error("Return probe requires an entry function.");
	if ((pp->offset || pp->line) && pp->retprobe)
		semantic_error("Offset/Line can't be used with return probe.");

	pr_debug("symbol:%s file:%s line:%d offset:%d, return:%d\n",
		 pp->function, pp->file, pp->line, pp->offset, pp->retprobe);
}

/* Parse an event definition. Note that any error must die. */
static void parse_probe_event(const char *str)
{
	char *argv[MAX_PROBE_ARGS + 2];	/* Event + probe + args */
	int argc, i;
	struct probe_point *pp = &session.probes[session.nr_probe];

	pr_debug("probe-definition(%d): %s\n", session.nr_probe, str);
	if (++session.nr_probe == MAX_PROBES)
		semantic_error("Too many probes");

	/* Separate arguments, similar to argv_split */
	argc = 0;
	do {
		/* Skip separators */
		while (isspace(*str))
			str++;

		/* Add an argument */
		if (*str != '\0') {
			const char *s = str;

			/* Skip the argument */
			while (!isspace(*str) && *str != '\0')
				str++;

			/* Duplicate the argument */
			argv[argc] = strndup(s, str - s);
			if (argv[argc] == NULL)
				die("strndup");
			if (++argc == MAX_PROBE_ARGS)
				semantic_error("Too many arguments");
			pr_debug("argv[%d]=%s\n", argc, argv[argc - 1]);
		}
	} while (*str != '\0');
	if (!argc)
		semantic_error("An empty argument.");

	/* Parse probe point */
	parse_probe_point(argv[0], pp);
	free(argv[0]);
	if (pp->file || pp->line)
		session.need_dwarf = 1;

	/* Copy arguments */
	pp->nr_args = argc - 1;
	if (pp->nr_args > 0) {
		pp->args = (char **)malloc(sizeof(char *) * pp->nr_args);
		if (!pp->args)
			die("malloc");
		memcpy(pp->args, &argv[1], sizeof(char *) * pp->nr_args);
	}

	/* Ensure return probe has no C argument */
	for (i = 0; i < pp->nr_args; i++)
		if (is_c_varname(pp->args[i])) {
			if (pp->retprobe)
				semantic_error("You can't specify local"
						" variable for kretprobe");
			session.need_dwarf = 1;
		}

	pr_debug("%d arguments\n", pp->nr_args);
}

static int opt_add_probe_event(const struct option *opt __used,
			      const char *str, int unset __used)
{
	if (str)
		parse_probe_event(str);
	return 0;
}

#ifndef NO_LIBDWARF
static int open_default_vmlinux(void)
{
	struct utsname uts;
	char fname[MAX_PATH_LEN];
	int fd, ret, i;

	ret = uname(&uts);
	if (ret) {
		pr_debug("uname() failed.\n");
		return -errno;
	}
	session.release = uts.release;
	for (i = 0; i < NR_SEARCH_PATH; i++) {
		ret = snprintf(fname, MAX_PATH_LEN,
			       default_search_path[i], session.release);
		if (ret >= MAX_PATH_LEN || ret < 0) {
			pr_debug("Filename(%d,%s) is too long.\n", i,
				uts.release);
			errno = E2BIG;
			return -E2BIG;
		}
		pr_debug("try to open %s\n", fname);
		fd = open(fname, O_RDONLY);
		if (fd >= 0)
			break;
	}
	return fd;
}
#endif

static const char * const probe_usage[] = {
	"perf probe [<options>] 'PROBEDEF' ['PROBEDEF' ...]",
	"perf probe [<options>] --add 'PROBEDEF' [--add 'PROBEDEF' ...]",
	NULL
};

static const struct option options[] = {
	OPT_BOOLEAN('v', "verbose", &verbose,
		    "be more verbose (show parsed arguments, etc)"),
#ifndef NO_LIBDWARF
	OPT_STRING('k', "vmlinux", &session.vmlinux, "file",
		"vmlinux/module pathname"),
#endif
	OPT_CALLBACK('a', "add", NULL,
#ifdef NO_LIBDWARF
		"FUNC[+OFFS|%return] [ARG ...]",
#else
		"FUNC[+OFFS|%return|:RLN][@SRC]|SRC:ALN [ARG ...]",
#endif
		"probe point definition, where\n"
		"\t\tGRP:\tGroup name (optional)\n"
		"\t\tNAME:\tEvent name\n"
		"\t\tFUNC:\tFunction name\n"
		"\t\tOFFS:\tOffset from function entry (in byte)\n"
		"\t\t%return:\tPut the probe at function return\n"
#ifdef NO_LIBDWARF
		"\t\tARG:\tProbe argument (only \n"
#else
		"\t\tSRC:\tSource code path\n"
		"\t\tRLN:\tRelative line number from function entry.\n"
		"\t\tALN:\tAbsolute line number in file.\n"
		"\t\tARG:\tProbe argument (local variable name or\n"
#endif
		"\t\t\tkprobe-tracer argument format is supported.)\n",
		opt_add_probe_event),
	OPT_END()
};

static int write_new_event(int fd, const char *buf)
{
	int ret;

	ret = write(fd, buf, strlen(buf));
	if (ret <= 0)
		die("Failed to create event.");
	else
		printf("Added new event: %s\n", buf);

	return ret;
}

#define MAX_CMDLEN 256

static int synthesize_probe_event(struct probe_point *pp)
{
	char *buf;
	int i, len, ret;
	pp->probes[0] = buf = zalloc(MAX_CMDLEN);
	if (!buf)
		die("Failed to allocate memory by zalloc.");
	ret = snprintf(buf, MAX_CMDLEN, "%s+%d", pp->function, pp->offset);
	if (ret <= 0 || ret >= MAX_CMDLEN)
		goto error;
	len = ret;

	for (i = 0; i < pp->nr_args; i++) {
		ret = snprintf(&buf[len], MAX_CMDLEN - len, " %s",
			       pp->args[i]);
		if (ret <= 0 || ret >= MAX_CMDLEN - len)
			goto error;
		len += ret;
	}
	pp->found = 1;
	return pp->found;
error:
	free(pp->probes[0]);
	if (ret > 0)
		ret = -E2BIG;
	return ret;
}

int cmd_probe(int argc, const char **argv, const char *prefix __used)
{
	int i, j, fd, ret;
	struct probe_point *pp;
	char buf[MAX_CMDLEN];

	argc = parse_options(argc, argv, options, probe_usage,
			     PARSE_OPT_STOP_AT_NON_OPTION);
	for (i = 0; i < argc; i++)
		parse_probe_event(argv[i]);

	if (session.nr_probe == 0)
		usage_with_options(probe_usage, options);

	if (session.need_dwarf)
#ifdef NO_LIBDWARF
		semantic_error("Debuginfo-analysis is not supported");
#else	/* !NO_LIBDWARF */
		pr_debug("Some probes require debuginfo.\n");

	if (session.vmlinux)
		fd = open(session.vmlinux, O_RDONLY);
	else
		fd = open_default_vmlinux();
	if (fd < 0) {
		if (session.need_dwarf)
			die("Could not open vmlinux/module file.");

		pr_warning("Could not open vmlinux/module file."
			   " Try to use symbols.\n");
		goto end_dwarf;
	}

	/* Searching probe points */
	for (j = 0; j < session.nr_probe; j++) {
		pp = &session.probes[j];
		if (pp->found)
			continue;

		lseek(fd, SEEK_SET, 0);
		ret = find_probepoint(fd, pp);
		if (ret < 0) {
			if (session.need_dwarf)
				die("Could not analyze debuginfo.");

			pr_warning("An error occurred in debuginfo analysis. Try to use symbols.\n");
			break;
		}
		if (ret == 0)	/* No error but failed to find probe point. */
			die("No probe point found.");
	}
	close(fd);

end_dwarf:
#endif /* !NO_LIBDWARF */

	/* Synthesize probes without dwarf */
	for (j = 0; j < session.nr_probe; j++) {
		pp = &session.probes[j];
		if (pp->found)	/* This probe is already found. */
			continue;

		ret = synthesize_probe_event(pp);
		if (ret == -E2BIG)
			semantic_error("probe point is too long.");
		else if (ret < 0)
			die("Failed to synthesize a probe point.");
	}

	/* Settng up probe points */
	snprintf(buf, MAX_CMDLEN, "%s/../kprobe_events", debugfs_path);
	fd = open(buf, O_WRONLY, O_APPEND);
	if (fd < 0) {
		if (errno == ENOENT)
			die("kprobe_events file does not exist - please rebuild with CONFIG_KPROBE_TRACER.");
		else
			die("Could not open kprobe_events file: %s",
			    strerror(errno));
	}
	for (j = 0; j < session.nr_probe; j++) {
		pp = &session.probes[j];
		if (pp->found == 1) {
			snprintf(buf, MAX_CMDLEN, "%c:%s/%s_%x %s\n",
				pp->retprobe ? 'r' : 'p', PERFPROBE_GROUP,
				pp->function, pp->offset, pp->probes[0]);
			write_new_event(fd, buf);
		} else
			for (i = 0; i < pp->found; i++) {
				snprintf(buf, MAX_CMDLEN, "%c:%s/%s_%x_%d %s\n",
					pp->retprobe ? 'r' : 'p',
					PERFPROBE_GROUP,
					pp->function, pp->offset, i,
					pp->probes[0]);
				write_new_event(fd, buf);
			}
	}
	close(fd);
	return 0;
}

OpenPOWER on IntegriCloud