xref: /openbmc/linux/tools/perf/util/pmu.c (revision 1a4e39c2e5ca2eb494a53ecd73055562f690bca0)
1 #include <linux/list.h>
2 #include <sys/types.h>
3 #include <unistd.h>
4 #include <stdio.h>
5 #include <stdbool.h>
6 #include <stdarg.h>
7 #include <dirent.h>
8 #include <api/fs/fs.h>
9 #include <locale.h>
10 #include "util.h"
11 #include "pmu.h"
12 #include "parse-events.h"
13 #include "cpumap.h"
14 
15 struct perf_pmu_format {
16 	char *name;
17 	int value;
18 	DECLARE_BITMAP(bits, PERF_PMU_FORMAT_BITS);
19 	struct list_head list;
20 };
21 
22 #define EVENT_SOURCE_DEVICE_PATH "/bus/event_source/devices/"
23 
24 int perf_pmu_parse(struct list_head *list, char *name);
25 extern FILE *perf_pmu_in;
26 
27 static LIST_HEAD(pmus);
28 
29 /*
30  * Parse & process all the sysfs attributes located under
31  * the directory specified in 'dir' parameter.
32  */
33 int perf_pmu__format_parse(char *dir, struct list_head *head)
34 {
35 	struct dirent *evt_ent;
36 	DIR *format_dir;
37 	int ret = 0;
38 
39 	format_dir = opendir(dir);
40 	if (!format_dir)
41 		return -EINVAL;
42 
43 	while (!ret && (evt_ent = readdir(format_dir))) {
44 		char path[PATH_MAX];
45 		char *name = evt_ent->d_name;
46 		FILE *file;
47 
48 		if (!strcmp(name, ".") || !strcmp(name, ".."))
49 			continue;
50 
51 		snprintf(path, PATH_MAX, "%s/%s", dir, name);
52 
53 		ret = -EINVAL;
54 		file = fopen(path, "r");
55 		if (!file)
56 			break;
57 
58 		perf_pmu_in = file;
59 		ret = perf_pmu_parse(head, name);
60 		fclose(file);
61 	}
62 
63 	closedir(format_dir);
64 	return ret;
65 }
66 
67 /*
68  * Reading/parsing the default pmu format definition, which should be
69  * located at:
70  * /sys/bus/event_source/devices/<dev>/format as sysfs group attributes.
71  */
72 static int pmu_format(const char *name, struct list_head *format)
73 {
74 	struct stat st;
75 	char path[PATH_MAX];
76 	const char *sysfs = sysfs__mountpoint();
77 
78 	if (!sysfs)
79 		return -1;
80 
81 	snprintf(path, PATH_MAX,
82 		 "%s" EVENT_SOURCE_DEVICE_PATH "%s/format", sysfs, name);
83 
84 	if (stat(path, &st) < 0)
85 		return 0;	/* no error if format does not exist */
86 
87 	if (perf_pmu__format_parse(path, format))
88 		return -1;
89 
90 	return 0;
91 }
92 
93 static int perf_pmu__parse_scale(struct perf_pmu_alias *alias, char *dir, char *name)
94 {
95 	struct stat st;
96 	ssize_t sret;
97 	char scale[128];
98 	int fd, ret = -1;
99 	char path[PATH_MAX];
100 	const char *lc;
101 
102 	snprintf(path, PATH_MAX, "%s/%s.scale", dir, name);
103 
104 	fd = open(path, O_RDONLY);
105 	if (fd == -1)
106 		return -1;
107 
108 	if (fstat(fd, &st) < 0)
109 		goto error;
110 
111 	sret = read(fd, scale, sizeof(scale)-1);
112 	if (sret < 0)
113 		goto error;
114 
115 	scale[sret] = '\0';
116 	/*
117 	 * save current locale
118 	 */
119 	lc = setlocale(LC_NUMERIC, NULL);
120 
121 	/*
122 	 * force to C locale to ensure kernel
123 	 * scale string is converted correctly.
124 	 * kernel uses default C locale.
125 	 */
126 	setlocale(LC_NUMERIC, "C");
127 
128 	alias->scale = strtod(scale, NULL);
129 
130 	/* restore locale */
131 	setlocale(LC_NUMERIC, lc);
132 
133 	ret = 0;
134 error:
135 	close(fd);
136 	return ret;
137 }
138 
139 static int perf_pmu__parse_unit(struct perf_pmu_alias *alias, char *dir, char *name)
140 {
141 	char path[PATH_MAX];
142 	ssize_t sret;
143 	int fd;
144 
145 	snprintf(path, PATH_MAX, "%s/%s.unit", dir, name);
146 
147 	fd = open(path, O_RDONLY);
148 	if (fd == -1)
149 		return -1;
150 
151 		sret = read(fd, alias->unit, UNIT_MAX_LEN);
152 	if (sret < 0)
153 		goto error;
154 
155 	close(fd);
156 
157 	alias->unit[sret] = '\0';
158 
159 	return 0;
160 error:
161 	close(fd);
162 	alias->unit[0] = '\0';
163 	return -1;
164 }
165 
166 static int perf_pmu__new_alias(struct list_head *list, char *dir, char *name, FILE *file)
167 {
168 	struct perf_pmu_alias *alias;
169 	char buf[256];
170 	int ret;
171 
172 	ret = fread(buf, 1, sizeof(buf), file);
173 	if (ret == 0)
174 		return -EINVAL;
175 	buf[ret] = 0;
176 
177 	alias = malloc(sizeof(*alias));
178 	if (!alias)
179 		return -ENOMEM;
180 
181 	INIT_LIST_HEAD(&alias->terms);
182 	alias->scale = 1.0;
183 	alias->unit[0] = '\0';
184 
185 	ret = parse_events_terms(&alias->terms, buf);
186 	if (ret) {
187 		free(alias);
188 		return ret;
189 	}
190 
191 	alias->name = strdup(name);
192 	/*
193 	 * load unit name and scale if available
194 	 */
195 	perf_pmu__parse_unit(alias, dir, name);
196 	perf_pmu__parse_scale(alias, dir, name);
197 
198 	list_add_tail(&alias->list, list);
199 
200 	return 0;
201 }
202 
203 static inline bool pmu_alias_info_file(char *name)
204 {
205 	size_t len;
206 
207 	len = strlen(name);
208 	if (len > 5 && !strcmp(name + len - 5, ".unit"))
209 		return true;
210 	if (len > 6 && !strcmp(name + len - 6, ".scale"))
211 		return true;
212 
213 	return false;
214 }
215 
216 /*
217  * Process all the sysfs attributes located under the directory
218  * specified in 'dir' parameter.
219  */
220 static int pmu_aliases_parse(char *dir, struct list_head *head)
221 {
222 	struct dirent *evt_ent;
223 	DIR *event_dir;
224 	int ret = 0;
225 
226 	event_dir = opendir(dir);
227 	if (!event_dir)
228 		return -EINVAL;
229 
230 	while (!ret && (evt_ent = readdir(event_dir))) {
231 		char path[PATH_MAX];
232 		char *name = evt_ent->d_name;
233 		FILE *file;
234 
235 		if (!strcmp(name, ".") || !strcmp(name, ".."))
236 			continue;
237 
238 		/*
239 		 * skip info files parsed in perf_pmu__new_alias()
240 		 */
241 		if (pmu_alias_info_file(name))
242 			continue;
243 
244 		snprintf(path, PATH_MAX, "%s/%s", dir, name);
245 
246 		ret = -EINVAL;
247 		file = fopen(path, "r");
248 		if (!file)
249 			break;
250 
251 		ret = perf_pmu__new_alias(head, dir, name, file);
252 		fclose(file);
253 	}
254 
255 	closedir(event_dir);
256 	return ret;
257 }
258 
259 /*
260  * Reading the pmu event aliases definition, which should be located at:
261  * /sys/bus/event_source/devices/<dev>/events as sysfs group attributes.
262  */
263 static int pmu_aliases(const char *name, struct list_head *head)
264 {
265 	struct stat st;
266 	char path[PATH_MAX];
267 	const char *sysfs = sysfs__mountpoint();
268 
269 	if (!sysfs)
270 		return -1;
271 
272 	snprintf(path, PATH_MAX,
273 		 "%s/bus/event_source/devices/%s/events", sysfs, name);
274 
275 	if (stat(path, &st) < 0)
276 		return 0;	 /* no error if 'events' does not exist */
277 
278 	if (pmu_aliases_parse(path, head))
279 		return -1;
280 
281 	return 0;
282 }
283 
284 static int pmu_alias_terms(struct perf_pmu_alias *alias,
285 			   struct list_head *terms)
286 {
287 	struct parse_events_term *term, *cloned;
288 	LIST_HEAD(list);
289 	int ret;
290 
291 	list_for_each_entry(term, &alias->terms, list) {
292 		ret = parse_events_term__clone(&cloned, term);
293 		if (ret) {
294 			parse_events__free_terms(&list);
295 			return ret;
296 		}
297 		list_add_tail(&cloned->list, &list);
298 	}
299 	list_splice(&list, terms);
300 	return 0;
301 }
302 
303 /*
304  * Reading/parsing the default pmu type value, which should be
305  * located at:
306  * /sys/bus/event_source/devices/<dev>/type as sysfs attribute.
307  */
308 static int pmu_type(const char *name, __u32 *type)
309 {
310 	struct stat st;
311 	char path[PATH_MAX];
312 	FILE *file;
313 	int ret = 0;
314 	const char *sysfs = sysfs__mountpoint();
315 
316 	if (!sysfs)
317 		return -1;
318 
319 	snprintf(path, PATH_MAX,
320 		 "%s" EVENT_SOURCE_DEVICE_PATH "%s/type", sysfs, name);
321 
322 	if (stat(path, &st) < 0)
323 		return -1;
324 
325 	file = fopen(path, "r");
326 	if (!file)
327 		return -EINVAL;
328 
329 	if (1 != fscanf(file, "%u", type))
330 		ret = -1;
331 
332 	fclose(file);
333 	return ret;
334 }
335 
336 /* Add all pmus in sysfs to pmu list: */
337 static void pmu_read_sysfs(void)
338 {
339 	char path[PATH_MAX];
340 	DIR *dir;
341 	struct dirent *dent;
342 	const char *sysfs = sysfs__mountpoint();
343 
344 	if (!sysfs)
345 		return;
346 
347 	snprintf(path, PATH_MAX,
348 		 "%s" EVENT_SOURCE_DEVICE_PATH, sysfs);
349 
350 	dir = opendir(path);
351 	if (!dir)
352 		return;
353 
354 	while ((dent = readdir(dir))) {
355 		if (!strcmp(dent->d_name, ".") || !strcmp(dent->d_name, ".."))
356 			continue;
357 		/* add to static LIST_HEAD(pmus): */
358 		perf_pmu__find(dent->d_name);
359 	}
360 
361 	closedir(dir);
362 }
363 
364 static struct cpu_map *pmu_cpumask(const char *name)
365 {
366 	struct stat st;
367 	char path[PATH_MAX];
368 	FILE *file;
369 	struct cpu_map *cpus;
370 	const char *sysfs = sysfs__mountpoint();
371 
372 	if (!sysfs)
373 		return NULL;
374 
375 	snprintf(path, PATH_MAX,
376 		 "%s/bus/event_source/devices/%s/cpumask", sysfs, name);
377 
378 	if (stat(path, &st) < 0)
379 		return NULL;
380 
381 	file = fopen(path, "r");
382 	if (!file)
383 		return NULL;
384 
385 	cpus = cpu_map__read(file);
386 	fclose(file);
387 	return cpus;
388 }
389 
390 struct perf_event_attr *__attribute__((weak))
391 perf_pmu__get_default_config(struct perf_pmu *pmu __maybe_unused)
392 {
393 	return NULL;
394 }
395 
396 static struct perf_pmu *pmu_lookup(const char *name)
397 {
398 	struct perf_pmu *pmu;
399 	LIST_HEAD(format);
400 	LIST_HEAD(aliases);
401 	__u32 type;
402 
403 	/*
404 	 * The pmu data we store & need consists of the pmu
405 	 * type value and format definitions. Load both right
406 	 * now.
407 	 */
408 	if (pmu_format(name, &format))
409 		return NULL;
410 
411 	if (pmu_aliases(name, &aliases))
412 		return NULL;
413 
414 	if (pmu_type(name, &type))
415 		return NULL;
416 
417 	pmu = zalloc(sizeof(*pmu));
418 	if (!pmu)
419 		return NULL;
420 
421 	pmu->cpus = pmu_cpumask(name);
422 
423 	INIT_LIST_HEAD(&pmu->format);
424 	INIT_LIST_HEAD(&pmu->aliases);
425 	list_splice(&format, &pmu->format);
426 	list_splice(&aliases, &pmu->aliases);
427 	pmu->name = strdup(name);
428 	pmu->type = type;
429 	list_add_tail(&pmu->list, &pmus);
430 
431 	pmu->default_config = perf_pmu__get_default_config(pmu);
432 
433 	return pmu;
434 }
435 
436 static struct perf_pmu *pmu_find(const char *name)
437 {
438 	struct perf_pmu *pmu;
439 
440 	list_for_each_entry(pmu, &pmus, list)
441 		if (!strcmp(pmu->name, name))
442 			return pmu;
443 
444 	return NULL;
445 }
446 
447 struct perf_pmu *perf_pmu__scan(struct perf_pmu *pmu)
448 {
449 	/*
450 	 * pmu iterator: If pmu is NULL, we start at the begin,
451 	 * otherwise return the next pmu. Returns NULL on end.
452 	 */
453 	if (!pmu) {
454 		pmu_read_sysfs();
455 		pmu = list_prepare_entry(pmu, &pmus, list);
456 	}
457 	list_for_each_entry_continue(pmu, &pmus, list)
458 		return pmu;
459 	return NULL;
460 }
461 
462 struct perf_pmu *perf_pmu__find(const char *name)
463 {
464 	struct perf_pmu *pmu;
465 
466 	/*
467 	 * Once PMU is loaded it stays in the list,
468 	 * so we keep us from multiple reading/parsing
469 	 * the pmu format definitions.
470 	 */
471 	pmu = pmu_find(name);
472 	if (pmu)
473 		return pmu;
474 
475 	return pmu_lookup(name);
476 }
477 
478 static struct perf_pmu_format *
479 pmu_find_format(struct list_head *formats, char *name)
480 {
481 	struct perf_pmu_format *format;
482 
483 	list_for_each_entry(format, formats, list)
484 		if (!strcmp(format->name, name))
485 			return format;
486 
487 	return NULL;
488 }
489 
490 /*
491  * Sets value based on the format definition (format parameter)
492  * and unformated value (value parameter).
493  */
494 static void pmu_format_value(unsigned long *format, __u64 value, __u64 *v,
495 			     bool zero)
496 {
497 	unsigned long fbit, vbit;
498 
499 	for (fbit = 0, vbit = 0; fbit < PERF_PMU_FORMAT_BITS; fbit++) {
500 
501 		if (!test_bit(fbit, format))
502 			continue;
503 
504 		if (value & (1llu << vbit++))
505 			*v |= (1llu << fbit);
506 		else if (zero)
507 			*v &= ~(1llu << fbit);
508 	}
509 }
510 
511 /*
512  * Setup one of config[12] attr members based on the
513  * user input data - term parameter.
514  */
515 static int pmu_config_term(struct list_head *formats,
516 			   struct perf_event_attr *attr,
517 			   struct parse_events_term *term,
518 			   bool zero)
519 {
520 	struct perf_pmu_format *format;
521 	__u64 *vp;
522 
523 	/*
524 	 * Support only for hardcoded and numnerial terms.
525 	 * Hardcoded terms should be already in, so nothing
526 	 * to be done for them.
527 	 */
528 	if (parse_events__is_hardcoded_term(term))
529 		return 0;
530 
531 	if (term->type_val != PARSE_EVENTS__TERM_TYPE_NUM)
532 		return -EINVAL;
533 
534 	format = pmu_find_format(formats, term->config);
535 	if (!format)
536 		return -EINVAL;
537 
538 	switch (format->value) {
539 	case PERF_PMU_FORMAT_VALUE_CONFIG:
540 		vp = &attr->config;
541 		break;
542 	case PERF_PMU_FORMAT_VALUE_CONFIG1:
543 		vp = &attr->config1;
544 		break;
545 	case PERF_PMU_FORMAT_VALUE_CONFIG2:
546 		vp = &attr->config2;
547 		break;
548 	default:
549 		return -EINVAL;
550 	}
551 
552 	/*
553 	 * XXX If we ever decide to go with string values for
554 	 * non-hardcoded terms, here's the place to translate
555 	 * them into value.
556 	 */
557 	pmu_format_value(format->bits, term->val.num, vp, zero);
558 	return 0;
559 }
560 
561 int perf_pmu__config_terms(struct list_head *formats,
562 			   struct perf_event_attr *attr,
563 			   struct list_head *head_terms,
564 			   bool zero)
565 {
566 	struct parse_events_term *term;
567 
568 	list_for_each_entry(term, head_terms, list)
569 		if (pmu_config_term(formats, attr, term, zero))
570 			return -EINVAL;
571 
572 	return 0;
573 }
574 
575 /*
576  * Configures event's 'attr' parameter based on the:
577  * 1) users input - specified in terms parameter
578  * 2) pmu format definitions - specified by pmu parameter
579  */
580 int perf_pmu__config(struct perf_pmu *pmu, struct perf_event_attr *attr,
581 		     struct list_head *head_terms)
582 {
583 	bool zero = !!pmu->default_config;
584 
585 	attr->type = pmu->type;
586 	return perf_pmu__config_terms(&pmu->format, attr, head_terms, zero);
587 }
588 
589 static struct perf_pmu_alias *pmu_find_alias(struct perf_pmu *pmu,
590 					     struct parse_events_term *term)
591 {
592 	struct perf_pmu_alias *alias;
593 	char *name;
594 
595 	if (parse_events__is_hardcoded_term(term))
596 		return NULL;
597 
598 	if (term->type_val == PARSE_EVENTS__TERM_TYPE_NUM) {
599 		if (term->val.num != 1)
600 			return NULL;
601 		if (pmu_find_format(&pmu->format, term->config))
602 			return NULL;
603 		name = term->config;
604 	} else if (term->type_val == PARSE_EVENTS__TERM_TYPE_STR) {
605 		if (strcasecmp(term->config, "event"))
606 			return NULL;
607 		name = term->val.str;
608 	} else {
609 		return NULL;
610 	}
611 
612 	list_for_each_entry(alias, &pmu->aliases, list) {
613 		if (!strcasecmp(alias->name, name))
614 			return alias;
615 	}
616 	return NULL;
617 }
618 
619 
620 static int check_unit_scale(struct perf_pmu_alias *alias,
621 			    const char **unit, double *scale)
622 {
623 	/*
624 	 * Only one term in event definition can
625 	 * define unit and scale, fail if there's
626 	 * more than one.
627 	 */
628 	if ((*unit && alias->unit) ||
629 	    (*scale && alias->scale))
630 		return -EINVAL;
631 
632 	if (alias->unit)
633 		*unit = alias->unit;
634 
635 	if (alias->scale)
636 		*scale = alias->scale;
637 
638 	return 0;
639 }
640 
641 /*
642  * Find alias in the terms list and replace it with the terms
643  * defined for the alias
644  */
645 int perf_pmu__check_alias(struct perf_pmu *pmu, struct list_head *head_terms,
646 			  struct perf_pmu_info *info)
647 {
648 	struct parse_events_term *term, *h;
649 	struct perf_pmu_alias *alias;
650 	int ret;
651 
652 	/*
653 	 * Mark unit and scale as not set
654 	 * (different from default values, see below)
655 	 */
656 	info->unit   = NULL;
657 	info->scale  = 0.0;
658 
659 	list_for_each_entry_safe(term, h, head_terms, list) {
660 		alias = pmu_find_alias(pmu, term);
661 		if (!alias)
662 			continue;
663 		ret = pmu_alias_terms(alias, &term->list);
664 		if (ret)
665 			return ret;
666 
667 		ret = check_unit_scale(alias, &info->unit, &info->scale);
668 		if (ret)
669 			return ret;
670 
671 		list_del(&term->list);
672 		free(term);
673 	}
674 
675 	/*
676 	 * if no unit or scale foundin aliases, then
677 	 * set defaults as for evsel
678 	 * unit cannot left to NULL
679 	 */
680 	if (info->unit == NULL)
681 		info->unit   = "";
682 
683 	if (info->scale == 0.0)
684 		info->scale  = 1.0;
685 
686 	return 0;
687 }
688 
689 int perf_pmu__new_format(struct list_head *list, char *name,
690 			 int config, unsigned long *bits)
691 {
692 	struct perf_pmu_format *format;
693 
694 	format = zalloc(sizeof(*format));
695 	if (!format)
696 		return -ENOMEM;
697 
698 	format->name = strdup(name);
699 	format->value = config;
700 	memcpy(format->bits, bits, sizeof(format->bits));
701 
702 	list_add_tail(&format->list, list);
703 	return 0;
704 }
705 
706 void perf_pmu__set_format(unsigned long *bits, long from, long to)
707 {
708 	long b;
709 
710 	if (!to)
711 		to = from;
712 
713 	memset(bits, 0, BITS_TO_BYTES(PERF_PMU_FORMAT_BITS));
714 	for (b = from; b <= to; b++)
715 		set_bit(b, bits);
716 }
717 
718 static char *format_alias(char *buf, int len, struct perf_pmu *pmu,
719 			  struct perf_pmu_alias *alias)
720 {
721 	snprintf(buf, len, "%s/%s/", pmu->name, alias->name);
722 	return buf;
723 }
724 
725 static char *format_alias_or(char *buf, int len, struct perf_pmu *pmu,
726 			     struct perf_pmu_alias *alias)
727 {
728 	snprintf(buf, len, "%s OR %s/%s/", alias->name, pmu->name, alias->name);
729 	return buf;
730 }
731 
732 static int cmp_string(const void *a, const void *b)
733 {
734 	const char * const *as = a;
735 	const char * const *bs = b;
736 	return strcmp(*as, *bs);
737 }
738 
739 void print_pmu_events(const char *event_glob, bool name_only)
740 {
741 	struct perf_pmu *pmu;
742 	struct perf_pmu_alias *alias;
743 	char buf[1024];
744 	int printed = 0;
745 	int len, j;
746 	char **aliases;
747 
748 	pmu = NULL;
749 	len = 0;
750 	while ((pmu = perf_pmu__scan(pmu)) != NULL)
751 		list_for_each_entry(alias, &pmu->aliases, list)
752 			len++;
753 	aliases = malloc(sizeof(char *) * len);
754 	if (!aliases)
755 		return;
756 	pmu = NULL;
757 	j = 0;
758 	while ((pmu = perf_pmu__scan(pmu)) != NULL)
759 		list_for_each_entry(alias, &pmu->aliases, list) {
760 			char *name = format_alias(buf, sizeof(buf), pmu, alias);
761 			bool is_cpu = !strcmp(pmu->name, "cpu");
762 
763 			if (event_glob != NULL &&
764 			    !(strglobmatch(name, event_glob) ||
765 			      (!is_cpu && strglobmatch(alias->name,
766 						       event_glob))))
767 				continue;
768 			aliases[j] = name;
769 			if (is_cpu && !name_only)
770 				aliases[j] = format_alias_or(buf, sizeof(buf),
771 							      pmu, alias);
772 			aliases[j] = strdup(aliases[j]);
773 			j++;
774 		}
775 	len = j;
776 	qsort(aliases, len, sizeof(char *), cmp_string);
777 	for (j = 0; j < len; j++) {
778 		if (name_only) {
779 			printf("%s ", aliases[j]);
780 			continue;
781 		}
782 		printf("  %-50s [Kernel PMU event]\n", aliases[j]);
783 		zfree(&aliases[j]);
784 		printed++;
785 	}
786 	if (printed)
787 		printf("\n");
788 	free(aliases);
789 }
790 
791 bool pmu_have_event(const char *pname, const char *name)
792 {
793 	struct perf_pmu *pmu;
794 	struct perf_pmu_alias *alias;
795 
796 	pmu = NULL;
797 	while ((pmu = perf_pmu__scan(pmu)) != NULL) {
798 		if (strcmp(pname, pmu->name))
799 			continue;
800 		list_for_each_entry(alias, &pmu->aliases, list)
801 			if (!strcmp(alias->name, name))
802 				return true;
803 	}
804 	return false;
805 }
806 
807 static FILE *perf_pmu__open_file(struct perf_pmu *pmu, const char *name)
808 {
809 	struct stat st;
810 	char path[PATH_MAX];
811 	const char *sysfs;
812 
813 	sysfs = sysfs__mountpoint();
814 	if (!sysfs)
815 		return NULL;
816 
817 	snprintf(path, PATH_MAX,
818 		 "%s" EVENT_SOURCE_DEVICE_PATH "%s/%s", sysfs, pmu->name, name);
819 
820 	if (stat(path, &st) < 0)
821 		return NULL;
822 
823 	return fopen(path, "r");
824 }
825 
826 int perf_pmu__scan_file(struct perf_pmu *pmu, const char *name, const char *fmt,
827 			...)
828 {
829 	va_list args;
830 	FILE *file;
831 	int ret = EOF;
832 
833 	va_start(args, fmt);
834 	file = perf_pmu__open_file(pmu, name);
835 	if (file) {
836 		ret = vfscanf(file, fmt, args);
837 		fclose(file);
838 	}
839 	va_end(args);
840 	return ret;
841 }
842