summaryrefslogtreecommitdiffstats
path: root/tools/perf/util/mmap.c
blob: 768c632b0d826389139a35cd8a002b549c0873cb (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
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2011-2017, Red Hat Inc, Arnaldo Carvalho de Melo <acme@redhat.com>
 *
 * Parts came from evlist.c builtin-{top,stat,record}.c, see those files for further
 * copyright notes.
 */

#include <sys/mman.h>
#include <inttypes.h>
#include <asm/bug.h>
#ifdef HAVE_LIBNUMA_SUPPORT
#include <numaif.h>
#endif
#include "debug.h"
#include "event.h"
#include "mmap.h"
#include "util.h" /* page_size */

size_t perf_mmap__mmap_len(struct perf_mmap *map)
{
	return map->mask + 1 + page_size;
}

/* When check_messup is true, 'end' must points to a good entry */
static union perf_event *perf_mmap__read(struct perf_mmap *map,
					 u64 *startp, u64 end)
{
	unsigned char *data = map->base + page_size;
	union perf_event *event = NULL;
	int diff = end - *startp;

	if (diff >= (int)sizeof(event->header)) {
		size_t size;

		event = (union perf_event *)&data[*startp & map->mask];
		size = event->header.size;

		if (size < sizeof(event->header) || diff < (int)size)
			return NULL;

		/*
		 * Event straddles the mmap boundary -- header should always
		 * be inside due to u64 alignment of output.
		 */
		if ((*startp & map->mask) + size != ((*startp + size) & map->mask)) {
			unsigned int offset = *startp;
			unsigned int len = min(sizeof(*event), size), cpy;
			void *dst = map->event_copy;

			do {
				cpy = min(map->mask + 1 - (offset & map->mask), len);
				memcpy(dst, &data[offset & map->mask], cpy);
				offset += cpy;
				dst += cpy;
				len -= cpy;
			} while (len);

			event = (union perf_event *)map->event_copy;
		}

		*startp += size;
	}

	return event;
}

/*
 * Read event from ring buffer one by one.
 * Return one event for each call.
 *
 * Usage:
 * perf_mmap__read_init()
 * while(event = perf_mmap__read_event()) {
 *	//process the event
 *	perf_mmap__consume()
 * }
 * perf_mmap__read_done()
 */
union perf_event *perf_mmap__read_event(struct perf_mmap *map)
{
	union perf_event *event;

	/*
	 * Check if event was unmapped due to a POLLHUP/POLLERR.
	 */
	if (!refcount_read(&map->refcnt))
		return NULL;

	/* non-overwirte doesn't pause the ringbuffer */
	if (!map->overwrite)
		map->end = perf_mmap__read_head(map);

	event = perf_mmap__read(map, &map->start, map->end);

	if (!map->overwrite)
		map->prev = map->start;

	return event;
}

static bool perf_mmap__empty(struct perf_mmap *map)
{
	return perf_mmap__read_head(map) == map->prev && !map->auxtrace_mmap.base;
}

void perf_mmap__get(struct perf_mmap *map)
{
	refcount_inc(&map->refcnt);
}

void perf_mmap__put(struct perf_mmap *map)
{
	BUG_ON(map->base && refcount_read(&map->refcnt) == 0);

	if (refcount_dec_and_test(&map->refcnt))
		perf_mmap__munmap(map);
}

void perf_mmap__consume(struct perf_mmap *map)
{
	if (!map->overwrite) {
		u64 old = map->prev;

		perf_mmap__write_tail(map, old);
	}

	if (refcount_read(&map->refcnt) == 1 && perf_mmap__empty(map))
		perf_mmap__put(map);
}

int __weak auxtrace_mmap__mmap(struct auxtrace_mmap *mm __maybe_unused,
			       struct auxtrace_mmap_params *mp __maybe_unused,
			       void *userpg __maybe_unused,
			       int fd __maybe_unused)
{
	return 0;
}

void __weak auxtrace_mmap__munmap(struct auxtrace_mmap *mm __maybe_unused)
{
}

void __weak auxtrace_mmap_params__init(struct auxtrace_mmap_params *mp __maybe_unused,
				       off_t auxtrace_offset __maybe_unused,
				       unsigned int auxtrace_pages __maybe_unused,
				       bool auxtrace_overwrite __maybe_unused)
{
}

void __weak auxtrace_mmap_params__set_idx(struct auxtrace_mmap_params *mp __maybe_unused,
					  struct perf_evlist *evlist __maybe_unused,
					  int idx __maybe_unused,
					  bool per_cpu __maybe_unused)
{
}

#ifdef HAVE_AIO_SUPPORT
static int perf_mmap__aio_enabled(struct perf_mmap *map)
{
	return map->aio.nr_cblocks > 0;
}

#ifdef HAVE_LIBNUMA_SUPPORT
static int perf_mmap__aio_alloc(struct perf_mmap *map, int idx)
{
	map->aio.data[idx] = mmap(NULL, perf_mmap__mmap_len(map), PROT_READ|PROT_WRITE,
				  MAP_PRIVATE|MAP_ANONYMOUS, 0, 0);
	if (map->aio.data[idx] == MAP_FAILED) {
		map->aio.data[idx] = NULL;
		return -1;
	}

	return 0;
}

static void perf_mmap__aio_free(struct perf_mmap *map, int idx)
{
	if (map->aio.data[idx]) {
		munmap(map->aio.data[idx], perf_mmap__mmap_len(map));
		map->aio.data[idx] = NULL;
	}
}

static int perf_mmap__aio_bind(struct perf_mmap *map, int idx, int cpu, int affinity)
{
	void *data;
	size_t mmap_len;
	unsigned long node_mask;

	if (affinity != PERF_AFFINITY_SYS && cpu__max_node() > 1) {
		data = map->aio.data[idx];
		mmap_len = perf_mmap__mmap_len(map);
		node_mask = 1UL << cpu__get_node(cpu);
		if (mbind(data, mmap_len, MPOL_BIND, &node_mask, 1, 0)) {
			pr_err("Failed to bind [%p-%p] AIO buffer to node %d: error %m\n",
				data, data + mmap_len, cpu__get_node(cpu));
			return -1;
		}
	}

	return 0;
}
#else /* !HAVE_LIBNUMA_SUPPORT */
static int perf_mmap__aio_alloc(struct perf_mmap *map, int idx)
{
	map->aio.data[idx] = malloc(perf_mmap__mmap_len(map));
	if (map->aio.data[idx] == NULL)
		return -1;

	return 0;
}

static void perf_mmap__aio_free(struct perf_mmap *map, int idx)
{
	zfree(&(map->aio.data[idx]));
}

static int perf_mmap__aio_bind(struct perf_mmap *map __maybe_unused, int idx __maybe_unused,
		int cpu __maybe_unused, int affinity __maybe_unused)
{
	return 0;
}
#endif

static int perf_mmap__aio_mmap(struct perf_mmap *map, struct mmap_params *mp)
{
	int delta_max, i, prio, ret;

	map->aio.nr_cblocks = mp->nr_cblocks;
	if (map->aio.nr_cblocks) {
		map->aio.aiocb = calloc(map->aio.nr_cblocks, sizeof(struct aiocb *));
		if (!map->aio.aiocb) {
			pr_debug2("failed to allocate aiocb for data buffer, error %m\n");
			return -1;
		}
		map->aio.cblocks = calloc(map->aio.nr_cblocks, sizeof(struct aiocb));
		if (!map->aio.cblocks) {
			pr_debug2("failed to allocate cblocks for data buffer, error %m\n");
			return -1;
		}
		map->aio.data = calloc(map->aio.nr_cblocks, sizeof(void *));
		if (!map->aio.data) {
			pr_debug2("failed to allocate data buffer, error %m\n");
			return -1;
		}
		delta_max = sysconf(_SC_AIO_PRIO_DELTA_MAX);
		for (i = 0; i < map->aio.nr_cblocks; ++i) {
			ret = perf_mmap__aio_alloc(map, i);
			if (ret == -1) {
				pr_debug2("failed to allocate data buffer area, error %m");
				return -1;
			}
			ret = perf_mmap__aio_bind(map, i, map->cpu, mp->affinity);
			if (ret == -1)
				return -1;
			/*
			 * Use cblock.aio_fildes value different from -1
			 * to denote started aio write operation on the
			 * cblock so it requires explicit record__aio_sync()
			 * call prior the cblock may be reused again.
			 */
			map->aio.cblocks[i].aio_fildes = -1;
			/*
			 * Allocate cblocks with priority delta to have
			 * faster aio write system calls because queued requests
			 * are kept in separate per-prio queues and adding
			 * a new request will iterate thru shorter per-prio
			 * list. Blocks with numbers higher than
			 *  _SC_AIO_PRIO_DELTA_MAX go with priority 0.
			 */
			prio = delta_max - i;
			map->aio.cblocks[i].aio_reqprio = prio >= 0 ? prio : 0;
		}
	}

	return 0;
}

static void perf_mmap__aio_munmap(struct perf_mmap *map)
{
	int i;

	for (i = 0; i < map->aio.nr_cblocks; ++i)
		perf_mmap__aio_free(map, i);
	if (map->aio.data)
		zfree(&map->aio.data);
	zfree(&map->aio.cblocks);
	zfree(&map->aio.aiocb);
}
#else /* !HAVE_AIO_SUPPORT */
static int perf_mmap__aio_enabled(struct perf_mmap *map __maybe_unused)
{
	return 0;
}

static int perf_mmap__aio_mmap(struct perf_mmap *map __maybe_unused,
			       struct mmap_params *mp __maybe_unused)
{
	return 0;
}

static void perf_mmap__aio_munmap(struct perf_mmap *map __maybe_unused)
{
}
#endif

void perf_mmap__munmap(struct perf_mmap *map)
{
	perf_mmap__aio_munmap(map);
	if (map->data != NULL) {
		munmap(map->data, perf_mmap__mmap_len(map));
		map->data = NULL;
	}
	if (map->base != NULL) {
		munmap(map->base, perf_mmap__mmap_len(map));
		map->base = NULL;
		map->fd = -1;
		refcount_set(&map->refcnt, 0);
	}
	auxtrace_mmap__munmap(&map->auxtrace_mmap);
}

static void build_node_mask(int node, cpu_set_t *mask)
{
	int c, cpu, nr_cpus;
	const struct cpu_map *cpu_map = NULL;

	cpu_map = cpu_map__online();
	if (!cpu_map)
		return;

	nr_cpus = cpu_map__nr(cpu_map);
	for (c = 0; c < nr_cpus; c++) {
		cpu = cpu_map->map[c]; /* map c index to online cpu index */
		if (cpu__get_node(cpu) == node)
			CPU_SET(cpu, mask);
	}
}

static void perf_mmap__setup_affinity_mask(struct perf_mmap *map, struct mmap_params *mp)
{
	CPU_ZERO(&map->affinity_mask);
	if (mp->affinity == PERF_AFFINITY_NODE && cpu__max_node() > 1)
		build_node_mask(cpu__get_node(map->cpu), &map->affinity_mask);
	else if (mp->affinity == PERF_AFFINITY_CPU)
		CPU_SET(map->cpu, &map->affinity_mask);
}

int perf_mmap__mmap(struct perf_mmap *map, struct mmap_params *mp, int fd, int cpu)
{
	/*
	 * The last one will be done at perf_mmap__consume(), so that we
	 * make sure we don't prevent tools from consuming every last event in
	 * the ring buffer.
	 *
	 * I.e. we can get the POLLHUP meaning that the fd doesn't exist
	 * anymore, but the last events for it are still in the ring buffer,
	 * waiting to be consumed.
	 *
	 * Tools can chose to ignore this at their own discretion, but the
	 * evlist layer can't just drop it when filtering events in
	 * perf_evlist__filter_pollfd().
	 */
	refcount_set(&map->refcnt, 2);
	map->prev = 0;
	map->mask = mp->mask;
	map->base = mmap(NULL, perf_mmap__mmap_len(map), mp->prot,
			 MAP_SHARED, fd, 0);
	if (map->base == MAP_FAILED) {
		pr_debug2("failed to mmap perf event ring buffer, error %d\n",
			  errno);
		map->base = NULL;
		return -1;
	}
	map->fd = fd;
	map->cpu = cpu;

	perf_mmap__setup_affinity_mask(map, mp);

	map->flush = mp->flush;

	map->comp_level = mp->comp_level;

	if (map->comp_level && !perf_mmap__aio_enabled(map)) {
		map->data = mmap(NULL, perf_mmap__mmap_len(map), PROT_READ|PROT_WRITE,
				 MAP_PRIVATE|MAP_ANONYMOUS, 0, 0);
		if (map->data == MAP_FAILED) {
			pr_debug2("failed to mmap data buffer, error %d\n",
					errno);
			map->data = NULL;
			return -1;
		}
	}

	if (auxtrace_mmap__mmap(&map->auxtrace_mmap,
				&mp->auxtrace_mp, map->base, fd))
		return -1;

	return perf_mmap__aio_mmap(map, mp);
}

static int overwrite_rb_find_range(void *buf, int mask, u64 *start, u64 *end)
{
	struct perf_event_header *pheader;
	u64 evt_head = *start;
	int size = mask + 1;

	pr_debug2("%s: buf=%p, start=%"PRIx64"\n", __func__, buf, *start);
	pheader = (struct perf_event_header *)(buf + (*start & mask));
	while (true) {
		if (evt_head - *start >= (unsigned int)size) {
			pr_debug("Finished reading overwrite ring buffer: rewind\n");
			if (evt_head - *start > (unsigned int)size)
				evt_head -= pheader->size;
			*end = evt_head;
			return 0;
		}

		pheader = (struct perf_event_header *)(buf + (evt_head & mask));

		if (pheader->size == 0) {
			pr_debug("Finished reading overwrite ring buffer: get start\n");
			*end = evt_head;
			return 0;
		}

		evt_head += pheader->size;
		pr_debug3("move evt_head: %"PRIx64"\n", evt_head);
	}
	WARN_ONCE(1, "Shouldn't get here\n");
	return -1;
}

/*
 * Report the start and end of the available data in ringbuffer
 */
static int __perf_mmap__read_init(struct perf_mmap *md)
{
	u64 head = perf_mmap__read_head(md);
	u64 old = md->prev;
	unsigned char *data = md->base + page_size;
	unsigned long size;

	md->start = md->overwrite ? head : old;
	md->end = md->overwrite ? old : head;

	if ((md->end - md->start) < md->flush)
		return -EAGAIN;

	size = md->end - md->start;
	if (size > (unsigned long)(md->mask) + 1) {
		if (!md->overwrite) {
			WARN_ONCE(1, "failed to keep up with mmap data. (warn only once)\n");

			md->prev = head;
			perf_mmap__consume(md);
			return -EAGAIN;
		}

		/*
		 * Backward ring buffer is full. We still have a chance to read
		 * most of data from it.
		 */
		if (overwrite_rb_find_range(data, md->mask, &md->start, &md->end))
			return -EINVAL;
	}

	return 0;
}

int perf_mmap__read_init(struct perf_mmap *map)
{
	/*
	 * Check if event was unmapped due to a POLLHUP/POLLERR.
	 */
	if (!refcount_read(&map->refcnt))
		return -ENOENT;

	return __perf_mmap__read_init(map);
}

int perf_mmap__push(struct perf_mmap *md, void *to,
		    int push(struct perf_mmap *map, void *to, void *buf, size_t size))
{
	u64 head = perf_mmap__read_head(md);
	unsigned char *data = md->base + page_size;
	unsigned long size;
	void *buf;
	int rc = 0;

	rc = perf_mmap__read_init(md);
	if (rc < 0)
		return (rc == -EAGAIN) ? 1 : -1;

	size = md->end - md->start;

	if ((md->start & md->mask) + size != (md->end & md->mask)) {
		buf = &data[md->start & md->mask];
		size = md->mask + 1 - (md->start & md->mask);
		md->start += size;

		if (push(md, to, buf, size) < 0) {
			rc = -1;
			goto out;
		}
	}

	buf = &data[md->start & md->mask];
	size = md->end - md->start;
	md->start += size;

	if (push(md, to, buf, size) < 0) {
		rc = -1;
		goto out;
	}

	md->prev = head;
	perf_mmap__consume(md);
out:
	return rc;
}

/*
 * Mandatory for overwrite mode
 * The direction of overwrite mode is backward.
 * The last perf_mmap__read() will set tail to map->prev.
 * Need to correct the map->prev to head which is the end of next read.
 */
void perf_mmap__read_done(struct perf_mmap *map)
{
	/*
	 * Check if event was unmapped due to a POLLHUP/POLLERR.
	 */
	if (!refcount_read(&map->refcnt))
		return;

	map->prev = perf_mmap__read_head(map);
}