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2024-10-09 05e59e5fb0064c97a1c10921ecd549f2d4a58565 
 kernel/kernel/events/ring_buffer.c
....@@ -1,3 +1,4 @@
1
+// SPDX-License-Identifier: GPL-2.0
12 /*
23  * Performance events ring-buffer code:
34  *
....@@ -5,8 +6,6 @@
56  *  Copyright (C) 2008-2011 Red Hat, Inc., Ingo Molnar
67  *  Copyright (C) 2008-2011 Red Hat, Inc., Peter Zijlstra
78  *  Copyright  ©  2009 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
8
- *
9
- * For licensing details see kernel-base/COPYING
109  */
1110 
1211 #include <linux/perf_event.h>
....@@ -36,17 +35,33 @@
3635  */
3736 static void perf_output_get_handle(struct perf_output_handle *handle)
3837 {
39
-	struct ring_buffer *rb = handle->rb;
38
+	struct perf_buffer *rb = handle->rb;
4039 
4140 	preempt_disable();
42
-	local_inc(&rb->nest);
41
+
42
+	/*
43
+	 * Avoid an explicit LOAD/STORE such that architectures with memops
44
+	 * can use them.
45
+	 */
46
+	(*(volatile unsigned int *)&rb->nest)++;
4347 	handle->wakeup = local_read(&rb->wakeup);
4448 }
4549 
4650 static void perf_output_put_handle(struct perf_output_handle *handle)
4751 {
48
-	struct ring_buffer *rb = handle->rb;
52
+	struct perf_buffer *rb = handle->rb;
4953 	unsigned long head;
54
+	unsigned int nest;
55
+
56
+	/*
57
+	 * If this isn't the outermost nesting, we don't have to update
58
+	 * @rb->user_page->data_head.
59
+	 */
60
+	nest = READ_ONCE(rb->nest);
61
+	if (nest > 1) {
62
+		WRITE_ONCE(rb->nest, nest - 1);
63
+		goto out;
64
+	}
5065 
5166 again:
5267 	/*
....@@ -64,15 +79,6 @@
6479 	 * IRQ/NMI can happen here and advance @rb->head, causing our
6580 	 * load above to be stale.
6681 	 */
67
-
68
-	/*
69
-	 * If this isn't the outermost nesting, we don't have to update
70
-	 * @rb->user_page->data_head.
71
-	 */
72
-	if (local_read(&rb->nest) > 1) {
73
-		local_dec(&rb->nest);
74
-		goto out;
75
-	}
7682 
7783 	/*
7884 	 * Since the mmap() consumer (userspace) can run on a different CPU:
....@@ -109,7 +115,7 @@
109115 	 * write will (temporarily) publish a stale value.
110116 	 */
111117 	barrier();
112
-	local_set(&rb->nest, 0);
118
+	WRITE_ONCE(rb->nest, 0);
113119 
114120 	/*
115121 	 * Ensure we decrement @rb->nest before we validate the @rb->head.
....@@ -117,7 +123,7 @@
117123 	 */
118124 	barrier();
119125 	if (unlikely(head != local_read(&rb->head))) {
120
-		local_inc(&rb->nest);
126
+		WRITE_ONCE(rb->nest, 1);
121127 		goto again;
122128 	}
123129 
....@@ -141,10 +147,11 @@
141147 
142148 static __always_inline int
143149 __perf_output_begin(struct perf_output_handle *handle,
150
+		    struct perf_sample_data *data,
144151 		    struct perf_event *event, unsigned int size,
145152 		    bool backward)
146153 {
147
-	struct ring_buffer *rb;
154
+	struct perf_buffer *rb;
148155 	unsigned long tail, offset, head;
149156 	int have_lost, page_shift;
150157 	struct {
....@@ -231,18 +238,16 @@
231238 	handle->size = (1UL << page_shift) - offset;
232239 
233240 	if (unlikely(have_lost)) {
234
-		struct perf_sample_data sample_data;
235
-
236241 		lost_event.header.size = sizeof(lost_event);
237242 		lost_event.header.type = PERF_RECORD_LOST;
238243 		lost_event.header.misc = 0;
239244 		lost_event.id          = event->id;
240245 		lost_event.lost        = local_xchg(&rb->lost, 0);
241246 
242
-		perf_event_header__init_id(&lost_event.header,
243
-					   &sample_data, event);
247
+		/* XXX mostly redundant; @data is already fully initializes */
248
+		perf_event_header__init_id(&lost_event.header, data, event);
244249 		perf_output_put(handle, lost_event);
245
-		perf_event__output_id_sample(event, handle, &sample_data);
250
+		perf_event__output_id_sample(event, handle, data);
246251 	}
247252 
248253 	return 0;
....@@ -257,22 +262,25 @@
257262 }
258263 
259264 int perf_output_begin_forward(struct perf_output_handle *handle,
260
-			     struct perf_event *event, unsigned int size)
265
+			      struct perf_sample_data *data,
266
+			      struct perf_event *event, unsigned int size)
261267 {
262
-	return __perf_output_begin(handle, event, size, false);
268
+	return __perf_output_begin(handle, data, event, size, false);
263269 }
264270 
265271 int perf_output_begin_backward(struct perf_output_handle *handle,
272
+			       struct perf_sample_data *data,
266273 			       struct perf_event *event, unsigned int size)
267274 {
268
-	return __perf_output_begin(handle, event, size, true);
275
+	return __perf_output_begin(handle, data, event, size, true);
269276 }
270277 
271278 int perf_output_begin(struct perf_output_handle *handle,
279
+		      struct perf_sample_data *data,
272280 		      struct perf_event *event, unsigned int size)
273281 {
274282 
275
-	return __perf_output_begin(handle, event, size,
283
+	return __perf_output_begin(handle, data, event, size,
276284 				   unlikely(is_write_backward(event)));
277285 }
278286 
....@@ -295,7 +303,7 @@
295303 }
296304 
297305 static void
298
-ring_buffer_init(struct ring_buffer *rb, long watermark, int flags)
306
+ring_buffer_init(struct perf_buffer *rb, long watermark, int flags)
299307 {
300308 	long max_size = perf_data_size(rb);
301309 
....@@ -310,7 +318,7 @@
310318 	else
311319 		rb->overwrite = 1;
312320 
313
-	atomic_set(&rb->refcount, 1);
321
+	refcount_set(&rb->refcount, 1);
314322 
315323 	INIT_LIST_HEAD(&rb->event_list);
316324 	spin_lock_init(&rb->event_lock);
....@@ -355,7 +363,8 @@
355363 {
356364 	struct perf_event *output_event = event;
357365 	unsigned long aux_head, aux_tail;
358
-	struct ring_buffer *rb;
366
+	struct perf_buffer *rb;
367
+	unsigned int nest;
359368 
360369 	if (output_event->parent)
361370 		output_event = output_event->parent;
....@@ -383,15 +392,18 @@
383392 	if (!atomic_read(&rb->aux_mmap_count))
384393 		goto err;
385394 
386
-	if (!atomic_inc_not_zero(&rb->aux_refcount))
395
+	if (!refcount_inc_not_zero(&rb->aux_refcount))
387396 		goto err;
388397 
398
+	nest = READ_ONCE(rb->aux_nest);
389399 	/*
390400 	 * Nesting is not supported for AUX area, make sure nested
391401 	 * writers are caught early
392402 	 */
393
-	if (WARN_ON_ONCE(local_xchg(&rb->aux_nest, 1)))
403
+	if (WARN_ON_ONCE(nest))
394404 		goto err_put;
405
+
406
+	WRITE_ONCE(rb->aux_nest, nest + 1);
395407 
396408 	aux_head = rb->aux_head;
397409 
....@@ -420,7 +432,7 @@
420432 		if (!handle->size) { /* A, matches D */
421433 			event->pending_disable = smp_processor_id();
422434 			perf_output_wakeup(handle);
423
-			local_set(&rb->aux_nest, 0);
435
+			WRITE_ONCE(rb->aux_nest, 0);
424436 			goto err_put;
425437 		}
426438 	}
....@@ -439,7 +451,7 @@
439451 }
440452 EXPORT_SYMBOL_GPL(perf_aux_output_begin);
441453 
442
-static __always_inline bool rb_need_aux_wakeup(struct ring_buffer *rb)
454
+static __always_inline bool rb_need_aux_wakeup(struct perf_buffer *rb)
443455 {
444456 	if (rb->aux_overwrite)
445457 		return false;
....@@ -465,7 +477,7 @@
465477 void perf_aux_output_end(struct perf_output_handle *handle, unsigned long size)
466478 {
467479 	bool wakeup = !!(handle->aux_flags & PERF_AUX_FLAG_TRUNCATED);
468
-	struct ring_buffer *rb = handle->rb;
480
+	struct perf_buffer *rb = handle->rb;
469481 	unsigned long aux_head;
470482 
471483 	/* in overwrite mode, driver provides aux_head via handle */
....@@ -481,14 +493,21 @@
481493 		rb->aux_head += size;
482494 	}
483495 
484
-	if (size || handle->aux_flags) {
485
-		/*
486
-		 * Only send RECORD_AUX if we have something useful to communicate
487
-		 */
488
-
496
+	/*
497
+	 * Only send RECORD_AUX if we have something useful to communicate
498
+	 *
499
+	 * Note: the OVERWRITE records by themselves are not considered
500
+	 * useful, as they don't communicate any *new* information,
501
+	 * aside from the short-lived offset, that becomes history at
502
+	 * the next event sched-in and therefore isn't useful.
503
+	 * The userspace that needs to copy out AUX data in overwrite
504
+	 * mode should know to use user_page::aux_head for the actual
505
+	 * offset. So, from now on we don't output AUX records that
506
+	 * have *only* OVERWRITE flag set.
507
+	 */
508
+	if (size || (handle->aux_flags & ~(u64)PERF_AUX_FLAG_OVERWRITE))
489509 		perf_event_aux_event(handle->event, aux_head, size,
490
-		                     handle->aux_flags);
491
-	}
510
+				     handle->aux_flags);
492511 
493512 	WRITE_ONCE(rb->user_page->aux_head, rb->aux_head);
494513 	if (rb_need_aux_wakeup(rb))
....@@ -502,7 +521,7 @@
502521 
503522 	handle->event = NULL;
504523 
505
-	local_set(&rb->aux_nest, 0);
524
+	WRITE_ONCE(rb->aux_nest, 0);
506525 	/* can't be last */
507526 	rb_free_aux(rb);
508527 	ring_buffer_put(rb);
....@@ -515,7 +534,7 @@
515534  */
516535 int perf_aux_output_skip(struct perf_output_handle *handle, unsigned long size)
517536 {
518
-	struct ring_buffer *rb = handle->rb;
537
+	struct perf_buffer *rb = handle->rb;
519538 
520539 	if (size > handle->size)
521540 		return -ENOSPC;
....@@ -545,6 +564,42 @@
545564 }
546565 EXPORT_SYMBOL_GPL(perf_get_aux);
547566 
567
+/*
568
+ * Copy out AUX data from an AUX handle.
569
+ */
570
+long perf_output_copy_aux(struct perf_output_handle *aux_handle,
571
+			  struct perf_output_handle *handle,
572
+			  unsigned long from, unsigned long to)
573
+{
574
+	struct perf_buffer *rb = aux_handle->rb;
575
+	unsigned long tocopy, remainder, len = 0;
576
+	void *addr;
577
+
578
+	from &= (rb->aux_nr_pages << PAGE_SHIFT) - 1;
579
+	to &= (rb->aux_nr_pages << PAGE_SHIFT) - 1;
580
+
581
+	do {
582
+		tocopy = PAGE_SIZE - offset_in_page(from);
583
+		if (to > from)
584
+			tocopy = min(tocopy, to - from);
585
+		if (!tocopy)
586
+			break;
587
+
588
+		addr = rb->aux_pages[from >> PAGE_SHIFT];
589
+		addr += offset_in_page(from);
590
+
591
+		remainder = perf_output_copy(handle, addr, tocopy);
592
+		if (remainder)
593
+			return -EFAULT;
594
+
595
+		len += tocopy;
596
+		from += tocopy;
597
+		from &= (rb->aux_nr_pages << PAGE_SHIFT) - 1;
598
+	} while (to != from);
599
+
600
+	return len;
601
+}
602
+
548603 #define PERF_AUX_GFP	(GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN | __GFP_NORETRY)
549604 
550605 static struct page *rb_alloc_aux_page(int node, int order)
....@@ -573,7 +628,7 @@
573628 	return page;
574629 }
575630 
576
-static void rb_free_aux_page(struct ring_buffer *rb, int idx)
631
+static void rb_free_aux_page(struct perf_buffer *rb, int idx)
577632 {
578633 	struct page *page = virt_to_page(rb->aux_pages[idx]);
579634 
....@@ -582,7 +637,7 @@
582637 	__free_page(page);
583638 }
584639 
585
-static void __rb_free_aux(struct ring_buffer *rb)
640
+static void __rb_free_aux(struct perf_buffer *rb)
586641 {
587642 	int pg;
588643 
....@@ -609,34 +664,31 @@
609664 	}
610665 }
611666 
612
-int rb_alloc_aux(struct ring_buffer *rb, struct perf_event *event,
667
+int rb_alloc_aux(struct perf_buffer *rb, struct perf_event *event,
613668 		 pgoff_t pgoff, int nr_pages, long watermark, int flags)
614669 {
615670 	bool overwrite = !(flags & RING_BUFFER_WRITABLE);
616671 	int node = (event->cpu == -1) ? -1 : cpu_to_node(event->cpu);
617
-	int ret = -ENOMEM, max_order = 0;
672
+	int ret = -ENOMEM, max_order;
618673 
619674 	if (!has_aux(event))
620675 		return -EOPNOTSUPP;
621676 
622
-	if (event->pmu->capabilities & PERF_PMU_CAP_AUX_NO_SG) {
623
-		/*
624
-		 * We need to start with the max_order that fits in nr_pages,
625
-		 * not the other way around, hence ilog2() and not get_order.
626
-		 */
627
-		max_order = ilog2(nr_pages);
677
+	/*
678
+	 * We need to start with the max_order that fits in nr_pages,
679
+	 * not the other way around, hence ilog2() and not get_order.
680
+	 */
681
+	max_order = ilog2(nr_pages);
628682 
629
-		/*
630
-		 * PMU requests more than one contiguous chunks of memory
631
-		 * for SW double buffering
632
-		 */
633
-		if ((event->pmu->capabilities & PERF_PMU_CAP_AUX_SW_DOUBLEBUF) &&
634
-		    !overwrite) {
635
-			if (!max_order)
636
-				return -EINVAL;
683
+	/*
684
+	 * PMU requests more than one contiguous chunks of memory
685
+	 * for SW double buffering
686
+	 */
687
+	if (!overwrite) {
688
+		if (!max_order)
689
+			return -EINVAL;
637690 
638
-			max_order--;
639
-		}
691
+		max_order--;
640692 	}
641693 
642694 	rb->aux_pages = kcalloc_node(nr_pages, sizeof(void *), GFP_KERNEL,
....@@ -686,7 +738,7 @@
686738 	 * we keep a refcount here to make sure either of the two can
687739 	 * reference them safely.
688740 	 */
689
-	atomic_set(&rb->aux_refcount, 1);
741
+	refcount_set(&rb->aux_refcount, 1);
690742 
691743 	rb->aux_overwrite = overwrite;
692744 	rb->aux_watermark = watermark;
....@@ -703,9 +755,9 @@
703755 	return ret;
704756 }
705757 
706
-void rb_free_aux(struct ring_buffer *rb)
758
+void rb_free_aux(struct perf_buffer *rb)
707759 {
708
-	if (atomic_dec_and_test(&rb->aux_refcount))
760
+	if (refcount_dec_and_test(&rb->aux_refcount))
709761 		__rb_free_aux(rb);
710762 }
711763 
....@@ -716,7 +768,7 @@
716768  */
717769 
718770 static struct page *
719
-__perf_mmap_to_page(struct ring_buffer *rb, unsigned long pgoff)
771
+__perf_mmap_to_page(struct perf_buffer *rb, unsigned long pgoff)
720772 {
721773 	if (pgoff > rb->nr_pages)
722774 		return NULL;
....@@ -740,13 +792,21 @@
740792 	return page_address(page);
741793 }
742794 
743
-struct ring_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags)
795
+static void perf_mmap_free_page(void *addr)
744796 {
745
-	struct ring_buffer *rb;
797
+	struct page *page = virt_to_page(addr);
798
+
799
+	page->mapping = NULL;
800
+	__free_page(page);
801
+}
802
+
803
+struct perf_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags)
804
+{
805
+	struct perf_buffer *rb;
746806 	unsigned long size;
747807 	int i;
748808 
749
-	size = sizeof(struct ring_buffer);
809
+	size = sizeof(struct perf_buffer);
750810 	size += nr_pages * sizeof(void *);
751811 
752812 	if (order_base_2(size) >= PAGE_SHIFT+MAX_ORDER)
....@@ -774,9 +834,9 @@
774834 
775835 fail_data_pages:
776836 	for (i--; i >= 0; i--)
777
-		free_page((unsigned long)rb->data_pages[i]);
837
+		perf_mmap_free_page(rb->data_pages[i]);
778838 
779
-	free_page((unsigned long)rb->user_page);
839
+	perf_mmap_free_page(rb->user_page);
780840 
781841 fail_user_page:
782842 	kfree(rb);
....@@ -785,32 +845,19 @@
785845 	return NULL;
786846 }
787847 
788
-static void perf_mmap_free_page(unsigned long addr)
789
-{
790
-	struct page *page = virt_to_page((void *)addr);
791
-
792
-	page->mapping = NULL;
793
-	__free_page(page);
794
-}
795
-
796
-void rb_free(struct ring_buffer *rb)
848
+void rb_free(struct perf_buffer *rb)
797849 {
798850 	int i;
799851 
800
-	perf_mmap_free_page((unsigned long)rb->user_page);
852
+	perf_mmap_free_page(rb->user_page);
801853 	for (i = 0; i < rb->nr_pages; i++)
802
-		perf_mmap_free_page((unsigned long)rb->data_pages[i]);
854
+		perf_mmap_free_page(rb->data_pages[i]);
803855 	kfree(rb);
804856 }
805857 
806858 #else
807
-static int data_page_nr(struct ring_buffer *rb)
808
-{
809
-	return rb->nr_pages << page_order(rb);
810
-}
811
-
812859 static struct page *
813
-__perf_mmap_to_page(struct ring_buffer *rb, unsigned long pgoff)
860
+__perf_mmap_to_page(struct perf_buffer *rb, unsigned long pgoff)
814861 {
815862 	/* The '>' counts in the user page. */
816863 	if (pgoff > data_page_nr(rb))
....@@ -828,11 +875,11 @@
828875 
829876 static void rb_free_work(struct work_struct *work)
830877 {
831
-	struct ring_buffer *rb;
878
+	struct perf_buffer *rb;
832879 	void *base;
833880 	int i, nr;
834881 
835
-	rb = container_of(work, struct ring_buffer, work);
882
+	rb = container_of(work, struct perf_buffer, work);
836883 	nr = data_page_nr(rb);
837884 
838885 	base = rb->user_page;
....@@ -844,18 +891,18 @@
844891 	kfree(rb);
845892 }
846893 
847
-void rb_free(struct ring_buffer *rb)
894
+void rb_free(struct perf_buffer *rb)
848895 {
849896 	schedule_work(&rb->work);
850897 }
851898 
852
-struct ring_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags)
899
+struct perf_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags)
853900 {
854
-	struct ring_buffer *rb;
901
+	struct perf_buffer *rb;
855902 	unsigned long size;
856903 	void *all_buf;
857904 
858
-	size = sizeof(struct ring_buffer);
905
+	size = sizeof(struct perf_buffer);
859906 	size += sizeof(void *);
860907 
861908 	rb = kzalloc(size, GFP_KERNEL);
....@@ -889,7 +936,7 @@
889936 #endif
890937 
891938 struct page *
892
-perf_mmap_to_page(struct ring_buffer *rb, unsigned long pgoff)
939
+perf_mmap_to_page(struct perf_buffer *rb, unsigned long pgoff)
893940 {
894941 	if (rb->aux_nr_pages) {
895942 		/* above AUX space */