xref: /openbmc/linux/tools/perf/arch/arm/util/cs-etm.c (revision f220d3eb)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright(C) 2015 Linaro Limited. All rights reserved.
4  * Author: Mathieu Poirier <mathieu.poirier@linaro.org>
5  */
6 
7 #include <api/fs/fs.h>
8 #include <linux/bitops.h>
9 #include <linux/compiler.h>
10 #include <linux/coresight-pmu.h>
11 #include <linux/kernel.h>
12 #include <linux/log2.h>
13 #include <linux/types.h>
14 
15 #include "cs-etm.h"
16 #include "../../perf.h"
17 #include "../../util/auxtrace.h"
18 #include "../../util/cpumap.h"
19 #include "../../util/evlist.h"
20 #include "../../util/evsel.h"
21 #include "../../util/pmu.h"
22 #include "../../util/thread_map.h"
23 #include "../../util/cs-etm.h"
24 
25 #include <stdlib.h>
26 #include <sys/stat.h>
27 
28 #define ENABLE_SINK_MAX	128
29 #define CS_BUS_DEVICE_PATH "/bus/coresight/devices/"
30 
31 struct cs_etm_recording {
32 	struct auxtrace_record	itr;
33 	struct perf_pmu		*cs_etm_pmu;
34 	struct perf_evlist	*evlist;
35 	bool			snapshot_mode;
36 	size_t			snapshot_size;
37 };
38 
39 static bool cs_etm_is_etmv4(struct auxtrace_record *itr, int cpu);
40 
41 static int cs_etm_parse_snapshot_options(struct auxtrace_record *itr,
42 					 struct record_opts *opts,
43 					 const char *str)
44 {
45 	struct cs_etm_recording *ptr =
46 				container_of(itr, struct cs_etm_recording, itr);
47 	unsigned long long snapshot_size = 0;
48 	char *endptr;
49 
50 	if (str) {
51 		snapshot_size = strtoull(str, &endptr, 0);
52 		if (*endptr || snapshot_size > SIZE_MAX)
53 			return -1;
54 	}
55 
56 	opts->auxtrace_snapshot_mode = true;
57 	opts->auxtrace_snapshot_size = snapshot_size;
58 	ptr->snapshot_size = snapshot_size;
59 
60 	return 0;
61 }
62 
63 static int cs_etm_recording_options(struct auxtrace_record *itr,
64 				    struct perf_evlist *evlist,
65 				    struct record_opts *opts)
66 {
67 	struct cs_etm_recording *ptr =
68 				container_of(itr, struct cs_etm_recording, itr);
69 	struct perf_pmu *cs_etm_pmu = ptr->cs_etm_pmu;
70 	struct perf_evsel *evsel, *cs_etm_evsel = NULL;
71 	const struct cpu_map *cpus = evlist->cpus;
72 	bool privileged = (geteuid() == 0 || perf_event_paranoid() < 0);
73 
74 	ptr->evlist = evlist;
75 	ptr->snapshot_mode = opts->auxtrace_snapshot_mode;
76 
77 	evlist__for_each_entry(evlist, evsel) {
78 		if (evsel->attr.type == cs_etm_pmu->type) {
79 			if (cs_etm_evsel) {
80 				pr_err("There may be only one %s event\n",
81 				       CORESIGHT_ETM_PMU_NAME);
82 				return -EINVAL;
83 			}
84 			evsel->attr.freq = 0;
85 			evsel->attr.sample_period = 1;
86 			cs_etm_evsel = evsel;
87 			opts->full_auxtrace = true;
88 		}
89 	}
90 
91 	/* no need to continue if at least one event of interest was found */
92 	if (!cs_etm_evsel)
93 		return 0;
94 
95 	if (opts->use_clockid) {
96 		pr_err("Cannot use clockid (-k option) with %s\n",
97 		       CORESIGHT_ETM_PMU_NAME);
98 		return -EINVAL;
99 	}
100 
101 	/* we are in snapshot mode */
102 	if (opts->auxtrace_snapshot_mode) {
103 		/*
104 		 * No size were given to '-S' or '-m,', so go with
105 		 * the default
106 		 */
107 		if (!opts->auxtrace_snapshot_size &&
108 		    !opts->auxtrace_mmap_pages) {
109 			if (privileged) {
110 				opts->auxtrace_mmap_pages = MiB(4) / page_size;
111 			} else {
112 				opts->auxtrace_mmap_pages =
113 							KiB(128) / page_size;
114 				if (opts->mmap_pages == UINT_MAX)
115 					opts->mmap_pages = KiB(256) / page_size;
116 			}
117 		} else if (!opts->auxtrace_mmap_pages && !privileged &&
118 						opts->mmap_pages == UINT_MAX) {
119 			opts->mmap_pages = KiB(256) / page_size;
120 		}
121 
122 		/*
123 		 * '-m,xyz' was specified but no snapshot size, so make the
124 		 * snapshot size as big as the auxtrace mmap area.
125 		 */
126 		if (!opts->auxtrace_snapshot_size) {
127 			opts->auxtrace_snapshot_size =
128 				opts->auxtrace_mmap_pages * (size_t)page_size;
129 		}
130 
131 		/*
132 		 * -Sxyz was specified but no auxtrace mmap area, so make the
133 		 * auxtrace mmap area big enough to fit the requested snapshot
134 		 * size.
135 		 */
136 		if (!opts->auxtrace_mmap_pages) {
137 			size_t sz = opts->auxtrace_snapshot_size;
138 
139 			sz = round_up(sz, page_size) / page_size;
140 			opts->auxtrace_mmap_pages = roundup_pow_of_two(sz);
141 		}
142 
143 		/* Snapshost size can't be bigger than the auxtrace area */
144 		if (opts->auxtrace_snapshot_size >
145 				opts->auxtrace_mmap_pages * (size_t)page_size) {
146 			pr_err("Snapshot size %zu must not be greater than AUX area tracing mmap size %zu\n",
147 			       opts->auxtrace_snapshot_size,
148 			       opts->auxtrace_mmap_pages * (size_t)page_size);
149 			return -EINVAL;
150 		}
151 
152 		/* Something went wrong somewhere - this shouldn't happen */
153 		if (!opts->auxtrace_snapshot_size ||
154 		    !opts->auxtrace_mmap_pages) {
155 			pr_err("Failed to calculate default snapshot size and/or AUX area tracing mmap pages\n");
156 			return -EINVAL;
157 		}
158 	}
159 
160 	/* We are in full trace mode but '-m,xyz' wasn't specified */
161 	if (opts->full_auxtrace && !opts->auxtrace_mmap_pages) {
162 		if (privileged) {
163 			opts->auxtrace_mmap_pages = MiB(4) / page_size;
164 		} else {
165 			opts->auxtrace_mmap_pages = KiB(128) / page_size;
166 			if (opts->mmap_pages == UINT_MAX)
167 				opts->mmap_pages = KiB(256) / page_size;
168 		}
169 
170 	}
171 
172 	/* Validate auxtrace_mmap_pages provided by user */
173 	if (opts->auxtrace_mmap_pages) {
174 		unsigned int max_page = (KiB(128) / page_size);
175 		size_t sz = opts->auxtrace_mmap_pages * (size_t)page_size;
176 
177 		if (!privileged &&
178 		    opts->auxtrace_mmap_pages > max_page) {
179 			opts->auxtrace_mmap_pages = max_page;
180 			pr_err("auxtrace too big, truncating to %d\n",
181 			       max_page);
182 		}
183 
184 		if (!is_power_of_2(sz)) {
185 			pr_err("Invalid mmap size for %s: must be a power of 2\n",
186 			       CORESIGHT_ETM_PMU_NAME);
187 			return -EINVAL;
188 		}
189 	}
190 
191 	if (opts->auxtrace_snapshot_mode)
192 		pr_debug2("%s snapshot size: %zu\n", CORESIGHT_ETM_PMU_NAME,
193 			  opts->auxtrace_snapshot_size);
194 
195 	/*
196 	 * To obtain the auxtrace buffer file descriptor, the auxtrace
197 	 * event must come first.
198 	 */
199 	perf_evlist__to_front(evlist, cs_etm_evsel);
200 
201 	/*
202 	 * In the case of per-cpu mmaps, we need the CPU on the
203 	 * AUX event.
204 	 */
205 	if (!cpu_map__empty(cpus))
206 		perf_evsel__set_sample_bit(cs_etm_evsel, CPU);
207 
208 	/* Add dummy event to keep tracking */
209 	if (opts->full_auxtrace) {
210 		struct perf_evsel *tracking_evsel;
211 		int err;
212 
213 		err = parse_events(evlist, "dummy:u", NULL);
214 		if (err)
215 			return err;
216 
217 		tracking_evsel = perf_evlist__last(evlist);
218 		perf_evlist__set_tracking_event(evlist, tracking_evsel);
219 
220 		tracking_evsel->attr.freq = 0;
221 		tracking_evsel->attr.sample_period = 1;
222 
223 		/* In per-cpu case, always need the time of mmap events etc */
224 		if (!cpu_map__empty(cpus))
225 			perf_evsel__set_sample_bit(tracking_evsel, TIME);
226 	}
227 
228 	return 0;
229 }
230 
231 static u64 cs_etm_get_config(struct auxtrace_record *itr)
232 {
233 	u64 config = 0;
234 	struct cs_etm_recording *ptr =
235 			container_of(itr, struct cs_etm_recording, itr);
236 	struct perf_pmu *cs_etm_pmu = ptr->cs_etm_pmu;
237 	struct perf_evlist *evlist = ptr->evlist;
238 	struct perf_evsel *evsel;
239 
240 	evlist__for_each_entry(evlist, evsel) {
241 		if (evsel->attr.type == cs_etm_pmu->type) {
242 			/*
243 			 * Variable perf_event_attr::config is assigned to
244 			 * ETMv3/PTM.  The bit fields have been made to match
245 			 * the ETMv3.5 ETRMCR register specification.  See the
246 			 * PMU_FORMAT_ATTR() declarations in
247 			 * drivers/hwtracing/coresight/coresight-perf.c for
248 			 * details.
249 			 */
250 			config = evsel->attr.config;
251 			break;
252 		}
253 	}
254 
255 	return config;
256 }
257 
258 #ifndef BIT
259 #define BIT(N) (1UL << (N))
260 #endif
261 
262 static u64 cs_etmv4_get_config(struct auxtrace_record *itr)
263 {
264 	u64 config = 0;
265 	u64 config_opts = 0;
266 
267 	/*
268 	 * The perf event variable config bits represent both
269 	 * the command line options and register programming
270 	 * bits in ETMv3/PTM. For ETMv4 we must remap options
271 	 * to real bits
272 	 */
273 	config_opts = cs_etm_get_config(itr);
274 	if (config_opts & BIT(ETM_OPT_CYCACC))
275 		config |= BIT(ETM4_CFG_BIT_CYCACC);
276 	if (config_opts & BIT(ETM_OPT_TS))
277 		config |= BIT(ETM4_CFG_BIT_TS);
278 	if (config_opts & BIT(ETM_OPT_RETSTK))
279 		config |= BIT(ETM4_CFG_BIT_RETSTK);
280 
281 	return config;
282 }
283 
284 static size_t
285 cs_etm_info_priv_size(struct auxtrace_record *itr __maybe_unused,
286 		      struct perf_evlist *evlist __maybe_unused)
287 {
288 	int i;
289 	int etmv3 = 0, etmv4 = 0;
290 	struct cpu_map *event_cpus = evlist->cpus;
291 	struct cpu_map *online_cpus = cpu_map__new(NULL);
292 
293 	/* cpu map is not empty, we have specific CPUs to work with */
294 	if (!cpu_map__empty(event_cpus)) {
295 		for (i = 0; i < cpu__max_cpu(); i++) {
296 			if (!cpu_map__has(event_cpus, i) ||
297 			    !cpu_map__has(online_cpus, i))
298 				continue;
299 
300 			if (cs_etm_is_etmv4(itr, i))
301 				etmv4++;
302 			else
303 				etmv3++;
304 		}
305 	} else {
306 		/* get configuration for all CPUs in the system */
307 		for (i = 0; i < cpu__max_cpu(); i++) {
308 			if (!cpu_map__has(online_cpus, i))
309 				continue;
310 
311 			if (cs_etm_is_etmv4(itr, i))
312 				etmv4++;
313 			else
314 				etmv3++;
315 		}
316 	}
317 
318 	cpu_map__put(online_cpus);
319 
320 	return (CS_ETM_HEADER_SIZE +
321 	       (etmv4 * CS_ETMV4_PRIV_SIZE) +
322 	       (etmv3 * CS_ETMV3_PRIV_SIZE));
323 }
324 
325 static const char *metadata_etmv3_ro[CS_ETM_PRIV_MAX] = {
326 	[CS_ETM_ETMCCER]	= "mgmt/etmccer",
327 	[CS_ETM_ETMIDR]		= "mgmt/etmidr",
328 };
329 
330 static const char *metadata_etmv4_ro[CS_ETMV4_PRIV_MAX] = {
331 	[CS_ETMV4_TRCIDR0]		= "trcidr/trcidr0",
332 	[CS_ETMV4_TRCIDR1]		= "trcidr/trcidr1",
333 	[CS_ETMV4_TRCIDR2]		= "trcidr/trcidr2",
334 	[CS_ETMV4_TRCIDR8]		= "trcidr/trcidr8",
335 	[CS_ETMV4_TRCAUTHSTATUS]	= "mgmt/trcauthstatus",
336 };
337 
338 static bool cs_etm_is_etmv4(struct auxtrace_record *itr, int cpu)
339 {
340 	bool ret = false;
341 	char path[PATH_MAX];
342 	int scan;
343 	unsigned int val;
344 	struct cs_etm_recording *ptr =
345 			container_of(itr, struct cs_etm_recording, itr);
346 	struct perf_pmu *cs_etm_pmu = ptr->cs_etm_pmu;
347 
348 	/* Take any of the RO files for ETMv4 and see if it present */
349 	snprintf(path, PATH_MAX, "cpu%d/%s",
350 		 cpu, metadata_etmv4_ro[CS_ETMV4_TRCIDR0]);
351 	scan = perf_pmu__scan_file(cs_etm_pmu, path, "%x", &val);
352 
353 	/* The file was read successfully, we have a winner */
354 	if (scan == 1)
355 		ret = true;
356 
357 	return ret;
358 }
359 
360 static int cs_etm_get_ro(struct perf_pmu *pmu, int cpu, const char *path)
361 {
362 	char pmu_path[PATH_MAX];
363 	int scan;
364 	unsigned int val = 0;
365 
366 	/* Get RO metadata from sysfs */
367 	snprintf(pmu_path, PATH_MAX, "cpu%d/%s", cpu, path);
368 
369 	scan = perf_pmu__scan_file(pmu, pmu_path, "%x", &val);
370 	if (scan != 1)
371 		pr_err("%s: error reading: %s\n", __func__, pmu_path);
372 
373 	return val;
374 }
375 
376 static void cs_etm_get_metadata(int cpu, u32 *offset,
377 				struct auxtrace_record *itr,
378 				struct auxtrace_info_event *info)
379 {
380 	u32 increment;
381 	u64 magic;
382 	struct cs_etm_recording *ptr =
383 			container_of(itr, struct cs_etm_recording, itr);
384 	struct perf_pmu *cs_etm_pmu = ptr->cs_etm_pmu;
385 
386 	/* first see what kind of tracer this cpu is affined to */
387 	if (cs_etm_is_etmv4(itr, cpu)) {
388 		magic = __perf_cs_etmv4_magic;
389 		/* Get trace configuration register */
390 		info->priv[*offset + CS_ETMV4_TRCCONFIGR] =
391 						cs_etmv4_get_config(itr);
392 		/* Get traceID from the framework */
393 		info->priv[*offset + CS_ETMV4_TRCTRACEIDR] =
394 						coresight_get_trace_id(cpu);
395 		/* Get read-only information from sysFS */
396 		info->priv[*offset + CS_ETMV4_TRCIDR0] =
397 			cs_etm_get_ro(cs_etm_pmu, cpu,
398 				      metadata_etmv4_ro[CS_ETMV4_TRCIDR0]);
399 		info->priv[*offset + CS_ETMV4_TRCIDR1] =
400 			cs_etm_get_ro(cs_etm_pmu, cpu,
401 				      metadata_etmv4_ro[CS_ETMV4_TRCIDR1]);
402 		info->priv[*offset + CS_ETMV4_TRCIDR2] =
403 			cs_etm_get_ro(cs_etm_pmu, cpu,
404 				      metadata_etmv4_ro[CS_ETMV4_TRCIDR2]);
405 		info->priv[*offset + CS_ETMV4_TRCIDR8] =
406 			cs_etm_get_ro(cs_etm_pmu, cpu,
407 				      metadata_etmv4_ro[CS_ETMV4_TRCIDR8]);
408 		info->priv[*offset + CS_ETMV4_TRCAUTHSTATUS] =
409 			cs_etm_get_ro(cs_etm_pmu, cpu,
410 				      metadata_etmv4_ro
411 				      [CS_ETMV4_TRCAUTHSTATUS]);
412 
413 		/* How much space was used */
414 		increment = CS_ETMV4_PRIV_MAX;
415 	} else {
416 		magic = __perf_cs_etmv3_magic;
417 		/* Get configuration register */
418 		info->priv[*offset + CS_ETM_ETMCR] = cs_etm_get_config(itr);
419 		/* Get traceID from the framework */
420 		info->priv[*offset + CS_ETM_ETMTRACEIDR] =
421 						coresight_get_trace_id(cpu);
422 		/* Get read-only information from sysFS */
423 		info->priv[*offset + CS_ETM_ETMCCER] =
424 			cs_etm_get_ro(cs_etm_pmu, cpu,
425 				      metadata_etmv3_ro[CS_ETM_ETMCCER]);
426 		info->priv[*offset + CS_ETM_ETMIDR] =
427 			cs_etm_get_ro(cs_etm_pmu, cpu,
428 				      metadata_etmv3_ro[CS_ETM_ETMIDR]);
429 
430 		/* How much space was used */
431 		increment = CS_ETM_PRIV_MAX;
432 	}
433 
434 	/* Build generic header portion */
435 	info->priv[*offset + CS_ETM_MAGIC] = magic;
436 	info->priv[*offset + CS_ETM_CPU] = cpu;
437 	/* Where the next CPU entry should start from */
438 	*offset += increment;
439 }
440 
441 static int cs_etm_info_fill(struct auxtrace_record *itr,
442 			    struct perf_session *session,
443 			    struct auxtrace_info_event *info,
444 			    size_t priv_size)
445 {
446 	int i;
447 	u32 offset;
448 	u64 nr_cpu, type;
449 	struct cpu_map *cpu_map;
450 	struct cpu_map *event_cpus = session->evlist->cpus;
451 	struct cpu_map *online_cpus = cpu_map__new(NULL);
452 	struct cs_etm_recording *ptr =
453 			container_of(itr, struct cs_etm_recording, itr);
454 	struct perf_pmu *cs_etm_pmu = ptr->cs_etm_pmu;
455 
456 	if (priv_size != cs_etm_info_priv_size(itr, session->evlist))
457 		return -EINVAL;
458 
459 	if (!session->evlist->nr_mmaps)
460 		return -EINVAL;
461 
462 	/* If the cpu_map is empty all online CPUs are involved */
463 	if (cpu_map__empty(event_cpus)) {
464 		cpu_map = online_cpus;
465 	} else {
466 		/* Make sure all specified CPUs are online */
467 		for (i = 0; i < cpu_map__nr(event_cpus); i++) {
468 			if (cpu_map__has(event_cpus, i) &&
469 			    !cpu_map__has(online_cpus, i))
470 				return -EINVAL;
471 		}
472 
473 		cpu_map = event_cpus;
474 	}
475 
476 	nr_cpu = cpu_map__nr(cpu_map);
477 	/* Get PMU type as dynamically assigned by the core */
478 	type = cs_etm_pmu->type;
479 
480 	/* First fill out the session header */
481 	info->type = PERF_AUXTRACE_CS_ETM;
482 	info->priv[CS_HEADER_VERSION_0] = 0;
483 	info->priv[CS_PMU_TYPE_CPUS] = type << 32;
484 	info->priv[CS_PMU_TYPE_CPUS] |= nr_cpu;
485 	info->priv[CS_ETM_SNAPSHOT] = ptr->snapshot_mode;
486 
487 	offset = CS_ETM_SNAPSHOT + 1;
488 
489 	for (i = 0; i < cpu__max_cpu() && offset < priv_size; i++)
490 		if (cpu_map__has(cpu_map, i))
491 			cs_etm_get_metadata(i, &offset, itr, info);
492 
493 	cpu_map__put(online_cpus);
494 
495 	return 0;
496 }
497 
498 static int cs_etm_find_snapshot(struct auxtrace_record *itr __maybe_unused,
499 				int idx, struct auxtrace_mmap *mm,
500 				unsigned char *data __maybe_unused,
501 				u64 *head, u64 *old)
502 {
503 	pr_debug3("%s: mmap index %d old head %zu new head %zu size %zu\n",
504 		  __func__, idx, (size_t)*old, (size_t)*head, mm->len);
505 
506 	*old = *head;
507 	*head += mm->len;
508 
509 	return 0;
510 }
511 
512 static int cs_etm_snapshot_start(struct auxtrace_record *itr)
513 {
514 	struct cs_etm_recording *ptr =
515 			container_of(itr, struct cs_etm_recording, itr);
516 	struct perf_evsel *evsel;
517 
518 	evlist__for_each_entry(ptr->evlist, evsel) {
519 		if (evsel->attr.type == ptr->cs_etm_pmu->type)
520 			return perf_evsel__disable(evsel);
521 	}
522 	return -EINVAL;
523 }
524 
525 static int cs_etm_snapshot_finish(struct auxtrace_record *itr)
526 {
527 	struct cs_etm_recording *ptr =
528 			container_of(itr, struct cs_etm_recording, itr);
529 	struct perf_evsel *evsel;
530 
531 	evlist__for_each_entry(ptr->evlist, evsel) {
532 		if (evsel->attr.type == ptr->cs_etm_pmu->type)
533 			return perf_evsel__enable(evsel);
534 	}
535 	return -EINVAL;
536 }
537 
538 static u64 cs_etm_reference(struct auxtrace_record *itr __maybe_unused)
539 {
540 	return (((u64) rand() <<  0) & 0x00000000FFFFFFFFull) |
541 		(((u64) rand() << 32) & 0xFFFFFFFF00000000ull);
542 }
543 
544 static void cs_etm_recording_free(struct auxtrace_record *itr)
545 {
546 	struct cs_etm_recording *ptr =
547 			container_of(itr, struct cs_etm_recording, itr);
548 	free(ptr);
549 }
550 
551 static int cs_etm_read_finish(struct auxtrace_record *itr, int idx)
552 {
553 	struct cs_etm_recording *ptr =
554 			container_of(itr, struct cs_etm_recording, itr);
555 	struct perf_evsel *evsel;
556 
557 	evlist__for_each_entry(ptr->evlist, evsel) {
558 		if (evsel->attr.type == ptr->cs_etm_pmu->type)
559 			return perf_evlist__enable_event_idx(ptr->evlist,
560 							     evsel, idx);
561 	}
562 
563 	return -EINVAL;
564 }
565 
566 struct auxtrace_record *cs_etm_record_init(int *err)
567 {
568 	struct perf_pmu *cs_etm_pmu;
569 	struct cs_etm_recording *ptr;
570 
571 	cs_etm_pmu = perf_pmu__find(CORESIGHT_ETM_PMU_NAME);
572 
573 	if (!cs_etm_pmu) {
574 		*err = -EINVAL;
575 		goto out;
576 	}
577 
578 	ptr = zalloc(sizeof(struct cs_etm_recording));
579 	if (!ptr) {
580 		*err = -ENOMEM;
581 		goto out;
582 	}
583 
584 	ptr->cs_etm_pmu			= cs_etm_pmu;
585 	ptr->itr.parse_snapshot_options	= cs_etm_parse_snapshot_options;
586 	ptr->itr.recording_options	= cs_etm_recording_options;
587 	ptr->itr.info_priv_size		= cs_etm_info_priv_size;
588 	ptr->itr.info_fill		= cs_etm_info_fill;
589 	ptr->itr.find_snapshot		= cs_etm_find_snapshot;
590 	ptr->itr.snapshot_start		= cs_etm_snapshot_start;
591 	ptr->itr.snapshot_finish	= cs_etm_snapshot_finish;
592 	ptr->itr.reference		= cs_etm_reference;
593 	ptr->itr.free			= cs_etm_recording_free;
594 	ptr->itr.read_finish		= cs_etm_read_finish;
595 
596 	*err = 0;
597 	return &ptr->itr;
598 out:
599 	return NULL;
600 }
601 
602 static FILE *cs_device__open_file(const char *name)
603 {
604 	struct stat st;
605 	char path[PATH_MAX];
606 	const char *sysfs;
607 
608 	sysfs = sysfs__mountpoint();
609 	if (!sysfs)
610 		return NULL;
611 
612 	snprintf(path, PATH_MAX,
613 		 "%s" CS_BUS_DEVICE_PATH "%s", sysfs, name);
614 
615 	if (stat(path, &st) < 0)
616 		return NULL;
617 
618 	return fopen(path, "w");
619 
620 }
621 
622 static int __printf(2, 3) cs_device__print_file(const char *name, const char *fmt, ...)
623 {
624 	va_list args;
625 	FILE *file;
626 	int ret = -EINVAL;
627 
628 	va_start(args, fmt);
629 	file = cs_device__open_file(name);
630 	if (file) {
631 		ret = vfprintf(file, fmt, args);
632 		fclose(file);
633 	}
634 	va_end(args);
635 	return ret;
636 }
637 
638 int cs_etm_set_drv_config(struct perf_evsel_config_term *term)
639 {
640 	int ret;
641 	char enable_sink[ENABLE_SINK_MAX];
642 
643 	snprintf(enable_sink, ENABLE_SINK_MAX, "%s/%s",
644 		 term->val.drv_cfg, "enable_sink");
645 
646 	ret = cs_device__print_file(enable_sink, "%d", 1);
647 	if (ret < 0)
648 		return ret;
649 
650 	return 0;
651 }
652