1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Performance events ring-buffer code:
4 *
5 * Copyright (C) 2008 Thomas Gleixner <tglx@linutronix.de>
6 * Copyright (C) 2008-2011 Red Hat, Inc., Ingo Molnar
7 * Copyright (C) 2008-2011 Red Hat, Inc., Peter Zijlstra
8 * Copyright © 2009 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
9 */
10
11#include <linux/perf_event.h>
12#include <linux/vmalloc.h>
13#include <linux/slab.h>
14#include <linux/circ_buf.h>
15#include <linux/poll.h>
16#include <linux/nospec.h>
17
18#include "internal.h"
19
20static void perf_output_wakeup(struct perf_output_handle *handle)
21{
22 atomic_set(v: &handle->rb->poll, EPOLLIN | EPOLLRDNORM);
23
24 handle->event->pending_wakeup = 1;
25
26 if (*perf_event_fasync(event: handle->event) && !handle->event->pending_kill)
27 handle->event->pending_kill = POLL_IN;
28
29 irq_work_queue(work: &handle->event->pending_irq);
30}
31
32/*
33 * We need to ensure a later event_id doesn't publish a head when a former
34 * event isn't done writing. However since we need to deal with NMIs we
35 * cannot fully serialize things.
36 *
37 * We only publish the head (and generate a wakeup) when the outer-most
38 * event completes.
39 */
40static void perf_output_get_handle(struct perf_output_handle *handle)
41{
42 struct perf_buffer *rb = handle->rb;
43
44 preempt_disable();
45
46 /*
47 * Avoid an explicit LOAD/STORE such that architectures with memops
48 * can use them.
49 */
50 (*(volatile unsigned int *)&rb->nest)++;
51 handle->wakeup = local_read(&rb->wakeup);
52}
53
54static void perf_output_put_handle(struct perf_output_handle *handle)
55{
56 struct perf_buffer *rb = handle->rb;
57 unsigned long head;
58 unsigned int nest;
59
60 /*
61 * If this isn't the outermost nesting, we don't have to update
62 * @rb->user_page->data_head.
63 */
64 nest = READ_ONCE(rb->nest);
65 if (nest > 1) {
66 WRITE_ONCE(rb->nest, nest - 1);
67 goto out;
68 }
69
70again:
71 /*
72 * In order to avoid publishing a head value that goes backwards,
73 * we must ensure the load of @rb->head happens after we've
74 * incremented @rb->nest.
75 *
76 * Otherwise we can observe a @rb->head value before one published
77 * by an IRQ/NMI happening between the load and the increment.
78 */
79 barrier();
80 head = local_read(&rb->head);
81
82 /*
83 * IRQ/NMI can happen here and advance @rb->head, causing our
84 * load above to be stale.
85 */
86
87 /*
88 * Since the mmap() consumer (userspace) can run on a different CPU:
89 *
90 * kernel user
91 *
92 * if (LOAD ->data_tail) { LOAD ->data_head
93 * (A) smp_rmb() (C)
94 * STORE $data LOAD $data
95 * smp_wmb() (B) smp_mb() (D)
96 * STORE ->data_head STORE ->data_tail
97 * }
98 *
99 * Where A pairs with D, and B pairs with C.
100 *
101 * In our case (A) is a control dependency that separates the load of
102 * the ->data_tail and the stores of $data. In case ->data_tail
103 * indicates there is no room in the buffer to store $data we do not.
104 *
105 * D needs to be a full barrier since it separates the data READ
106 * from the tail WRITE.
107 *
108 * For B a WMB is sufficient since it separates two WRITEs, and for C
109 * an RMB is sufficient since it separates two READs.
110 *
111 * See perf_output_begin().
112 */
113 smp_wmb(); /* B, matches C */
114 WRITE_ONCE(rb->user_page->data_head, head);
115
116 /*
117 * We must publish the head before decrementing the nest count,
118 * otherwise an IRQ/NMI can publish a more recent head value and our
119 * write will (temporarily) publish a stale value.
120 */
121 barrier();
122 WRITE_ONCE(rb->nest, 0);
123
124 /*
125 * Ensure we decrement @rb->nest before we validate the @rb->head.
126 * Otherwise we cannot be sure we caught the 'last' nested update.
127 */
128 barrier();
129 if (unlikely(head != local_read(&rb->head))) {
130 WRITE_ONCE(rb->nest, 1);
131 goto again;
132 }
133
134 if (handle->wakeup != local_read(&rb->wakeup))
135 perf_output_wakeup(handle);
136
137out:
138 preempt_enable();
139}
140
141static __always_inline bool
142ring_buffer_has_space(unsigned long head, unsigned long tail,
143 unsigned long data_size, unsigned int size,
144 bool backward)
145{
146 if (!backward)
147 return CIRC_SPACE(head, tail, data_size) >= size;
148 else
149 return CIRC_SPACE(tail, head, data_size) >= size;
150}
151
152static __always_inline int
153__perf_output_begin(struct perf_output_handle *handle,
154 struct perf_sample_data *data,
155 struct perf_event *event, unsigned int size,
156 bool backward)
157{
158 struct perf_buffer *rb;
159 unsigned long tail, offset, head;
160 int have_lost, page_shift;
161 struct {
162 struct perf_event_header header;
163 u64 id;
164 u64 lost;
165 } lost_event;
166
167 rcu_read_lock();
168 /*
169 * For inherited events we send all the output towards the parent.
170 */
171 if (event->parent)
172 event = event->parent;
173
174 rb = rcu_dereference(event->rb);
175 if (unlikely(!rb))
176 goto out;
177
178 if (unlikely(rb->paused)) {
179 if (rb->nr_pages) {
180 local_inc(l: &rb->lost);
181 atomic64_inc(v: &event->lost_samples);
182 }
183 goto out;
184 }
185
186 handle->rb = rb;
187 handle->event = event;
188 handle->flags = 0;
189
190 have_lost = local_read(&rb->lost);
191 if (unlikely(have_lost)) {
192 size += sizeof(lost_event);
193 if (event->attr.sample_id_all)
194 size += event->id_header_size;
195 }
196
197 perf_output_get_handle(handle);
198
199 offset = local_read(&rb->head);
200 do {
201 head = offset;
202 tail = READ_ONCE(rb->user_page->data_tail);
203 if (!rb->overwrite) {
204 if (unlikely(!ring_buffer_has_space(head, tail,
205 perf_data_size(rb),
206 size, backward)))
207 goto fail;
208 }
209
210 /*
211 * The above forms a control dependency barrier separating the
212 * @tail load above from the data stores below. Since the @tail
213 * load is required to compute the branch to fail below.
214 *
215 * A, matches D; the full memory barrier userspace SHOULD issue
216 * after reading the data and before storing the new tail
217 * position.
218 *
219 * See perf_output_put_handle().
220 */
221
222 if (!backward)
223 head += size;
224 else
225 head -= size;
226 } while (!local_try_cmpxchg(l: &rb->head, old: &offset, new: head));
227
228 if (backward) {
229 offset = head;
230 head = (u64)(-head);
231 }
232
233 /*
234 * We rely on the implied barrier() by local_cmpxchg() to ensure
235 * none of the data stores below can be lifted up by the compiler.
236 */
237
238 if (unlikely(head - local_read(&rb->wakeup) > rb->watermark))
239 local_add(i: rb->watermark, l: &rb->wakeup);
240
241 page_shift = PAGE_SHIFT + page_order(rb);
242
243 handle->page = (offset >> page_shift) & (rb->nr_pages - 1);
244 offset &= (1UL << page_shift) - 1;
245 handle->addr = rb->data_pages[handle->page] + offset;
246 handle->size = (1UL << page_shift) - offset;
247
248 if (unlikely(have_lost)) {
249 lost_event.header.size = sizeof(lost_event);
250 lost_event.header.type = PERF_RECORD_LOST;
251 lost_event.header.misc = 0;
252 lost_event.id = event->id;
253 lost_event.lost = local_xchg(l: &rb->lost, n: 0);
254
255 /* XXX mostly redundant; @data is already fully initializes */
256 perf_event_header__init_id(header: &lost_event.header, data, event);
257 perf_output_put(handle, lost_event);
258 perf_event__output_id_sample(event, handle, sample: data);
259 }
260
261 return 0;
262
263fail:
264 local_inc(l: &rb->lost);
265 atomic64_inc(v: &event->lost_samples);
266 perf_output_put_handle(handle);
267out:
268 rcu_read_unlock();
269
270 return -ENOSPC;
271}
272
273int perf_output_begin_forward(struct perf_output_handle *handle,
274 struct perf_sample_data *data,
275 struct perf_event *event, unsigned int size)
276{
277 return __perf_output_begin(handle, data, event, size, backward: false);
278}
279
280int perf_output_begin_backward(struct perf_output_handle *handle,
281 struct perf_sample_data *data,
282 struct perf_event *event, unsigned int size)
283{
284 return __perf_output_begin(handle, data, event, size, backward: true);
285}
286
287int perf_output_begin(struct perf_output_handle *handle,
288 struct perf_sample_data *data,
289 struct perf_event *event, unsigned int size)
290{
291
292 return __perf_output_begin(handle, data, event, size,
293 unlikely(is_write_backward(event)));
294}
295
296unsigned int perf_output_copy(struct perf_output_handle *handle,
297 const void *buf, unsigned int len)
298{
299 return __output_copy(handle, buf, len);
300}
301
302unsigned int perf_output_skip(struct perf_output_handle *handle,
303 unsigned int len)
304{
305 return __output_skip(handle, NULL, len);
306}
307
308void perf_output_end(struct perf_output_handle *handle)
309{
310 perf_output_put_handle(handle);
311 rcu_read_unlock();
312}
313
314static void
315ring_buffer_init(struct perf_buffer *rb, long watermark, int flags)
316{
317 long max_size = perf_data_size(rb);
318
319 if (watermark)
320 rb->watermark = min(max_size, watermark);
321
322 if (!rb->watermark)
323 rb->watermark = max_size / 2;
324
325 if (flags & RING_BUFFER_WRITABLE)
326 rb->overwrite = 0;
327 else
328 rb->overwrite = 1;
329
330 refcount_set(r: &rb->refcount, n: 1);
331
332 INIT_LIST_HEAD(list: &rb->event_list);
333 spin_lock_init(&rb->event_lock);
334
335 /*
336 * perf_output_begin() only checks rb->paused, therefore
337 * rb->paused must be true if we have no pages for output.
338 */
339 if (!rb->nr_pages)
340 rb->paused = 1;
341
342 mutex_init(&rb->aux_mutex);
343}
344
345void perf_aux_output_flag(struct perf_output_handle *handle, u64 flags)
346{
347 /*
348 * OVERWRITE is determined by perf_aux_output_end() and can't
349 * be passed in directly.
350 */
351 if (WARN_ON_ONCE(flags & PERF_AUX_FLAG_OVERWRITE))
352 return;
353
354 handle->aux_flags |= flags;
355}
356EXPORT_SYMBOL_GPL(perf_aux_output_flag);
357
358/*
359 * This is called before hardware starts writing to the AUX area to
360 * obtain an output handle and make sure there's room in the buffer.
361 * When the capture completes, call perf_aux_output_end() to commit
362 * the recorded data to the buffer.
363 *
364 * The ordering is similar to that of perf_output_{begin,end}, with
365 * the exception of (B), which should be taken care of by the pmu
366 * driver, since ordering rules will differ depending on hardware.
367 *
368 * Call this from pmu::start(); see the comment in perf_aux_output_end()
369 * about its use in pmu callbacks. Both can also be called from the PMI
370 * handler if needed.
371 */
372void *perf_aux_output_begin(struct perf_output_handle *handle,
373 struct perf_event *event)
374{
375 struct perf_event *output_event = event;
376 unsigned long aux_head, aux_tail;
377 struct perf_buffer *rb;
378 unsigned int nest;
379
380 if (output_event->parent)
381 output_event = output_event->parent;
382
383 /*
384 * Since this will typically be open across pmu::add/pmu::del, we
385 * grab ring_buffer's refcount instead of holding rcu read lock
386 * to make sure it doesn't disappear under us.
387 */
388 rb = ring_buffer_get(event: output_event);
389 if (!rb)
390 return NULL;
391
392 if (!rb_has_aux(rb))
393 goto err;
394
395 /*
396 * If aux_mmap_count is zero, the aux buffer is in perf_mmap_close(),
397 * about to get freed, so we leave immediately.
398 *
399 * Checking rb::aux_mmap_count and rb::refcount has to be done in
400 * the same order, see perf_mmap_close. Otherwise we end up freeing
401 * aux pages in this path, which is a bug, because in_atomic().
402 */
403 if (!refcount_read(r: &rb->aux_mmap_count))
404 goto err;
405
406 if (!refcount_inc_not_zero(r: &rb->aux_refcount))
407 goto err;
408
409 nest = READ_ONCE(rb->aux_nest);
410 /*
411 * Nesting is not supported for AUX area, make sure nested
412 * writers are caught early
413 */
414 if (WARN_ON_ONCE(nest))
415 goto err_put;
416
417 WRITE_ONCE(rb->aux_nest, nest + 1);
418
419 aux_head = rb->aux_head;
420
421 handle->rb = rb;
422 handle->event = event;
423 handle->head = aux_head;
424 handle->size = 0;
425 handle->aux_flags = 0;
426
427 /*
428 * In overwrite mode, AUX data stores do not depend on aux_tail,
429 * therefore (A) control dependency barrier does not exist. The
430 * (B) <-> (C) ordering is still observed by the pmu driver.
431 */
432 if (!rb->aux_overwrite) {
433 aux_tail = READ_ONCE(rb->user_page->aux_tail);
434 handle->wakeup = rb->aux_wakeup + rb->aux_watermark;
435 if (aux_head - aux_tail < perf_aux_size(rb))
436 handle->size = CIRC_SPACE(aux_head, aux_tail, perf_aux_size(rb));
437
438 /*
439 * handle->size computation depends on aux_tail load; this forms a
440 * control dependency barrier separating aux_tail load from aux data
441 * store that will be enabled on successful return
442 */
443 if (!handle->size) { /* A, matches D */
444 perf_event_disable_inatomic(event: handle->event);
445 perf_output_wakeup(handle);
446 WRITE_ONCE(rb->aux_nest, 0);
447 goto err_put;
448 }
449 }
450
451 return handle->rb->aux_priv;
452
453err_put:
454 /* can't be last */
455 rb_free_aux(rb);
456
457err:
458 ring_buffer_put(rb);
459 handle->event = NULL;
460
461 return NULL;
462}
463EXPORT_SYMBOL_GPL(perf_aux_output_begin);
464
465static __always_inline bool rb_need_aux_wakeup(struct perf_buffer *rb)
466{
467 if (rb->aux_overwrite)
468 return false;
469
470 if (rb->aux_head - rb->aux_wakeup >= rb->aux_watermark) {
471 rb->aux_wakeup = rounddown(rb->aux_head, rb->aux_watermark);
472 return true;
473 }
474
475 return false;
476}
477
478/*
479 * Commit the data written by hardware into the ring buffer by adjusting
480 * aux_head and posting a PERF_RECORD_AUX into the perf buffer. It is the
481 * pmu driver's responsibility to observe ordering rules of the hardware,
482 * so that all the data is externally visible before this is called.
483 *
484 * Note: this has to be called from pmu::stop() callback, as the assumption
485 * of the AUX buffer management code is that after pmu::stop(), the AUX
486 * transaction must be stopped and therefore drop the AUX reference count.
487 */
488void perf_aux_output_end(struct perf_output_handle *handle, unsigned long size)
489{
490 bool wakeup = !!(handle->aux_flags & PERF_AUX_FLAG_TRUNCATED);
491 struct perf_buffer *rb = handle->rb;
492 unsigned long aux_head;
493
494 /* in overwrite mode, driver provides aux_head via handle */
495 if (rb->aux_overwrite) {
496 handle->aux_flags |= PERF_AUX_FLAG_OVERWRITE;
497
498 aux_head = handle->head;
499 rb->aux_head = aux_head;
500 } else {
501 handle->aux_flags &= ~PERF_AUX_FLAG_OVERWRITE;
502
503 aux_head = rb->aux_head;
504 rb->aux_head += size;
505 }
506
507 /*
508 * Only send RECORD_AUX if we have something useful to communicate
509 *
510 * Note: the OVERWRITE records by themselves are not considered
511 * useful, as they don't communicate any *new* information,
512 * aside from the short-lived offset, that becomes history at
513 * the next event sched-in and therefore isn't useful.
514 * The userspace that needs to copy out AUX data in overwrite
515 * mode should know to use user_page::aux_head for the actual
516 * offset. So, from now on we don't output AUX records that
517 * have *only* OVERWRITE flag set.
518 */
519 if (size || (handle->aux_flags & ~(u64)PERF_AUX_FLAG_OVERWRITE))
520 perf_event_aux_event(event: handle->event, head: aux_head, size,
521 flags: handle->aux_flags);
522
523 WRITE_ONCE(rb->user_page->aux_head, rb->aux_head);
524 if (rb_need_aux_wakeup(rb))
525 wakeup = true;
526
527 if (wakeup) {
528 if (handle->aux_flags & PERF_AUX_FLAG_TRUNCATED)
529 perf_event_disable_inatomic(event: handle->event);
530 perf_output_wakeup(handle);
531 }
532
533 handle->event = NULL;
534
535 WRITE_ONCE(rb->aux_nest, 0);
536 /* can't be last */
537 rb_free_aux(rb);
538 ring_buffer_put(rb);
539}
540EXPORT_SYMBOL_GPL(perf_aux_output_end);
541
542/*
543 * Skip over a given number of bytes in the AUX buffer, due to, for example,
544 * hardware's alignment constraints.
545 */
546int perf_aux_output_skip(struct perf_output_handle *handle, unsigned long size)
547{
548 struct perf_buffer *rb = handle->rb;
549
550 if (size > handle->size)
551 return -ENOSPC;
552
553 rb->aux_head += size;
554
555 WRITE_ONCE(rb->user_page->aux_head, rb->aux_head);
556 if (rb_need_aux_wakeup(rb)) {
557 perf_output_wakeup(handle);
558 handle->wakeup = rb->aux_wakeup + rb->aux_watermark;
559 }
560
561 handle->head = rb->aux_head;
562 handle->size -= size;
563
564 return 0;
565}
566EXPORT_SYMBOL_GPL(perf_aux_output_skip);
567
568void *perf_get_aux(struct perf_output_handle *handle)
569{
570 /* this is only valid between perf_aux_output_begin and *_end */
571 if (!handle->event)
572 return NULL;
573
574 return handle->rb->aux_priv;
575}
576EXPORT_SYMBOL_GPL(perf_get_aux);
577
578/*
579 * Copy out AUX data from an AUX handle.
580 */
581long perf_output_copy_aux(struct perf_output_handle *aux_handle,
582 struct perf_output_handle *handle,
583 unsigned long from, unsigned long to)
584{
585 struct perf_buffer *rb = aux_handle->rb;
586 unsigned long tocopy, remainder, len = 0;
587 void *addr;
588
589 from &= (rb->aux_nr_pages << PAGE_SHIFT) - 1;
590 to &= (rb->aux_nr_pages << PAGE_SHIFT) - 1;
591
592 do {
593 tocopy = PAGE_SIZE - offset_in_page(from);
594 if (to > from)
595 tocopy = min(tocopy, to - from);
596 if (!tocopy)
597 break;
598
599 addr = rb->aux_pages[from >> PAGE_SHIFT];
600 addr += offset_in_page(from);
601
602 remainder = perf_output_copy(handle, buf: addr, len: tocopy);
603 if (remainder)
604 return -EFAULT;
605
606 len += tocopy;
607 from += tocopy;
608 from &= (rb->aux_nr_pages << PAGE_SHIFT) - 1;
609 } while (to != from);
610
611 return len;
612}
613
614#define PERF_AUX_GFP (GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN | __GFP_NORETRY)
615
616static struct page *rb_alloc_aux_page(int node, int order)
617{
618 struct page *page;
619
620 if (order > MAX_PAGE_ORDER)
621 order = MAX_PAGE_ORDER;
622
623 do {
624 page = alloc_pages_node(node, PERF_AUX_GFP, order);
625 } while (!page && order--);
626
627 if (page && order) {
628 /*
629 * Communicate the allocation size to the driver:
630 * if we managed to secure a high-order allocation,
631 * set its first page's private to this order;
632 * !PagePrivate(page) means it's just a normal page.
633 */
634 split_page(page, order);
635 SetPagePrivate(page);
636 set_page_private(page, private: order);
637 }
638
639 return page;
640}
641
642static void rb_free_aux_page(struct perf_buffer *rb, int idx)
643{
644 struct page *page = virt_to_page(rb->aux_pages[idx]);
645
646 ClearPagePrivate(page);
647 __free_page(page);
648}
649
650static void __rb_free_aux(struct perf_buffer *rb)
651{
652 int pg;
653
654 /*
655 * Should never happen, the last reference should be dropped from
656 * perf_mmap_close() path, which first stops aux transactions (which
657 * in turn are the atomic holders of aux_refcount) and then does the
658 * last rb_free_aux().
659 */
660 WARN_ON_ONCE(in_atomic());
661
662 if (rb->aux_priv) {
663 rb->free_aux(rb->aux_priv);
664 rb->free_aux = NULL;
665 rb->aux_priv = NULL;
666 }
667
668 if (rb->aux_nr_pages) {
669 for (pg = 0; pg < rb->aux_nr_pages; pg++)
670 rb_free_aux_page(rb, idx: pg);
671
672 kfree(objp: rb->aux_pages);
673 rb->aux_nr_pages = 0;
674 }
675}
676
677int rb_alloc_aux(struct perf_buffer *rb, struct perf_event *event,
678 pgoff_t pgoff, int nr_pages, long watermark, int flags)
679{
680 bool overwrite = !(flags & RING_BUFFER_WRITABLE);
681 int node = (event->cpu == -1) ? -1 : cpu_to_node(cpu: event->cpu);
682 bool use_contiguous_pages = event->pmu->capabilities & (
683 PERF_PMU_CAP_AUX_NO_SG | PERF_PMU_CAP_AUX_PREFER_LARGE);
684 /*
685 * Initialize max_order to 0 for page allocation. This allocates single
686 * pages to minimize memory fragmentation. This is overridden if the
687 * PMU needs or prefers contiguous pages (use_contiguous_pages = true).
688 */
689 int max_order = 0;
690 int ret = -ENOMEM;
691
692 if (!has_aux(event))
693 return -EOPNOTSUPP;
694
695 if (nr_pages <= 0)
696 return -EINVAL;
697
698 if (!overwrite) {
699 /*
700 * Watermark defaults to half the buffer, to aid PMU drivers
701 * in double buffering.
702 */
703 if (!watermark)
704 watermark = min_t(unsigned long,
705 U32_MAX,
706 (unsigned long)nr_pages << (PAGE_SHIFT - 1));
707
708 /*
709 * If using contiguous pages, use aux_watermark as the basis
710 * for chunking to help PMU drivers honor the watermark.
711 */
712 if (use_contiguous_pages)
713 max_order = get_order(size: watermark);
714 } else {
715 /*
716 * If using contiguous pages, we need to start with the
717 * max_order that fits in nr_pages, not the other way around,
718 * hence ilog2() and not get_order.
719 */
720 if (use_contiguous_pages)
721 max_order = ilog2(nr_pages);
722 watermark = 0;
723 }
724
725 /*
726 * kcalloc_node() is unable to allocate buffer if the size is larger
727 * than: PAGE_SIZE << MAX_PAGE_ORDER; directly bail out in this case.
728 */
729 if (get_order(size: (unsigned long)nr_pages * sizeof(void *)) > MAX_PAGE_ORDER)
730 return -ENOMEM;
731 rb->aux_pages = kcalloc_node(nr_pages, sizeof(void *), GFP_KERNEL,
732 node);
733 if (!rb->aux_pages)
734 return -ENOMEM;
735
736 rb->free_aux = event->pmu->free_aux;
737 for (rb->aux_nr_pages = 0; rb->aux_nr_pages < nr_pages;) {
738 struct page *page;
739 int last, order;
740
741 order = min(max_order, ilog2(nr_pages - rb->aux_nr_pages));
742 page = rb_alloc_aux_page(node, order);
743 if (!page)
744 goto out;
745
746 for (last = rb->aux_nr_pages + (1 << page_private(page));
747 last > rb->aux_nr_pages; rb->aux_nr_pages++)
748 rb->aux_pages[rb->aux_nr_pages] = page_address(page++);
749 }
750
751 /*
752 * In overwrite mode, PMUs that don't support SG may not handle more
753 * than one contiguous allocation, since they rely on PMI to do double
754 * buffering. In this case, the entire buffer has to be one contiguous
755 * chunk.
756 */
757 if ((event->pmu->capabilities & PERF_PMU_CAP_AUX_NO_SG) &&
758 overwrite) {
759 struct page *page = virt_to_page(rb->aux_pages[0]);
760
761 if (page_private(page) != max_order)
762 goto out;
763 }
764
765 rb->aux_priv = event->pmu->setup_aux(event, rb->aux_pages, nr_pages,
766 overwrite);
767 if (!rb->aux_priv)
768 goto out;
769
770 ret = 0;
771
772 /*
773 * aux_pages (and pmu driver's private data, aux_priv) will be
774 * referenced in both producer's and consumer's contexts, thus
775 * we keep a refcount here to make sure either of the two can
776 * reference them safely.
777 */
778 refcount_set(r: &rb->aux_refcount, n: 1);
779
780 rb->aux_overwrite = overwrite;
781 rb->aux_watermark = watermark;
782
783out:
784 if (!ret)
785 rb->aux_pgoff = pgoff;
786 else
787 __rb_free_aux(rb);
788
789 return ret;
790}
791
792void rb_free_aux(struct perf_buffer *rb)
793{
794 if (refcount_dec_and_test(r: &rb->aux_refcount))
795 __rb_free_aux(rb);
796}
797
798#ifndef CONFIG_PERF_USE_VMALLOC
799
800/*
801 * Back perf_mmap() with regular GFP_KERNEL-0 pages.
802 */
803
804static struct page *
805__perf_mmap_to_page(struct perf_buffer *rb, unsigned long pgoff)
806{
807 if (pgoff > rb->nr_pages)
808 return NULL;
809
810 if (pgoff == 0)
811 return virt_to_page(rb->user_page);
812
813 return virt_to_page(rb->data_pages[pgoff - 1]);
814}
815
816static void *perf_mmap_alloc_page(int cpu)
817{
818 struct page *page;
819 int node;
820
821 node = (cpu == -1) ? cpu : cpu_to_node(cpu);
822 page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0);
823 if (!page)
824 return NULL;
825
826 return page_address(page);
827}
828
829static void perf_mmap_free_page(void *addr)
830{
831 struct page *page = virt_to_page(addr);
832
833 __free_page(page);
834}
835
836struct perf_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags)
837{
838 struct perf_buffer *rb;
839 unsigned long size;
840 int i, node;
841
842 size = sizeof(struct perf_buffer);
843 size += nr_pages * sizeof(void *);
844
845 if (order_base_2(size) > PAGE_SHIFT+MAX_PAGE_ORDER)
846 goto fail;
847
848 node = (cpu == -1) ? cpu : cpu_to_node(cpu);
849 rb = kzalloc_node(size, GFP_KERNEL, node);
850 if (!rb)
851 goto fail;
852
853 rb->user_page = perf_mmap_alloc_page(cpu);
854 if (!rb->user_page)
855 goto fail_user_page;
856
857 for (i = 0; i < nr_pages; i++) {
858 rb->data_pages[i] = perf_mmap_alloc_page(cpu);
859 if (!rb->data_pages[i])
860 goto fail_data_pages;
861 }
862
863 rb->nr_pages = nr_pages;
864
865 ring_buffer_init(rb, watermark, flags);
866
867 return rb;
868
869fail_data_pages:
870 for (i--; i >= 0; i--)
871 perf_mmap_free_page(addr: rb->data_pages[i]);
872
873 perf_mmap_free_page(addr: rb->user_page);
874
875fail_user_page:
876 kfree(objp: rb);
877
878fail:
879 return NULL;
880}
881
882void rb_free(struct perf_buffer *rb)
883{
884 int i;
885
886 perf_mmap_free_page(addr: rb->user_page);
887 for (i = 0; i < rb->nr_pages; i++)
888 perf_mmap_free_page(addr: rb->data_pages[i]);
889 kfree(objp: rb);
890}
891
892#else
893static struct page *
894__perf_mmap_to_page(struct perf_buffer *rb, unsigned long pgoff)
895{
896 /* The '>' counts in the user page. */
897 if (pgoff > data_page_nr(rb))
898 return NULL;
899
900 return vmalloc_to_page((void *)rb->user_page + pgoff * PAGE_SIZE);
901}
902
903static void rb_free_work(struct work_struct *work)
904{
905 struct perf_buffer *rb;
906
907 rb = container_of(work, struct perf_buffer, work);
908
909 vfree(rb->user_page);
910 kfree(rb);
911}
912
913void rb_free(struct perf_buffer *rb)
914{
915 schedule_work(&rb->work);
916}
917
918struct perf_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags)
919{
920 struct perf_buffer *rb;
921 unsigned long size;
922 void *all_buf;
923 int node;
924
925 size = sizeof(struct perf_buffer);
926 size += sizeof(void *);
927
928 node = (cpu == -1) ? cpu : cpu_to_node(cpu);
929 rb = kzalloc_node(size, GFP_KERNEL, node);
930 if (!rb)
931 goto fail;
932
933 INIT_WORK(&rb->work, rb_free_work);
934
935 all_buf = vmalloc_user((nr_pages + 1) * PAGE_SIZE);
936 if (!all_buf)
937 goto fail_all_buf;
938
939 rb->user_page = all_buf;
940 rb->data_pages[0] = all_buf + PAGE_SIZE;
941 if (nr_pages) {
942 rb->nr_pages = 1;
943 rb->page_order = ilog2(nr_pages);
944 }
945
946 ring_buffer_init(rb, watermark, flags);
947
948 return rb;
949
950fail_all_buf:
951 kfree(rb);
952
953fail:
954 return NULL;
955}
956
957#endif
958
959struct page *
960perf_mmap_to_page(struct perf_buffer *rb, unsigned long pgoff)
961{
962 if (rb->aux_nr_pages) {
963 /* above AUX space */
964 if (pgoff > rb->aux_pgoff + rb->aux_nr_pages)
965 return NULL;
966
967 /* AUX space */
968 if (pgoff >= rb->aux_pgoff) {
969 int aux_pgoff = array_index_nospec(pgoff - rb->aux_pgoff, rb->aux_nr_pages);
970 return virt_to_page(rb->aux_pages[aux_pgoff]);
971 }
972 }
973
974 return __perf_mmap_to_page(rb, pgoff);
975}
976