[GitHub/mt8127/android_kernel_alcatel_ttab.git] / kernel / events / ring_buffer.c

/*
 * Performance events ring-buffer code:
 *
 *  Copyright (C) 2008 Thomas Gleixner <tglx@linutronix.de>
 *  Copyright (C) 2008-2011 Red Hat, Inc., Ingo Molnar
 *  Copyright (C) 2008-2011 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
 *  Copyright  ©  2009 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
 *
 * For licensing details see kernel-base/COPYING
 */

#include <linux/perf_event.h>
#include <linux/vmalloc.h>
#include <linux/slab.h>

#include "internal.h"

static bool perf_output_space(struct ring_buffer *rb, unsigned long tail,
			      unsigned long offset, unsigned long head)
{
	unsigned long sz = perf_data_size(rb);
	unsigned long mask = sz - 1;

	/*
	 * check if user-writable
	 * overwrite : over-write its own tail
	 * !overwrite: buffer possibly drops events.
	 */
	if (rb->overwrite)
		return true;

	/*
	 * verify that payload is not bigger than buffer
	 * otherwise masking logic may fail to detect
	 * the "not enough space" condition
	 */
	if ((head - offset) > sz)
		return false;

	offset = (offset - tail) & mask;
	head   = (head   - tail) & mask;

	if ((int)(head - offset) < 0)
		return false;

	return true;
}

static void perf_output_wakeup(struct perf_output_handle *handle)
{
	atomic_set(&handle->rb->poll, POLL_IN);

	handle->event->pending_wakeup = 1;
	irq_work_queue(&handle->event->pending);
}

/*
 * We need to ensure a later event_id doesn't publish a head when a former
 * event isn't done writing. However since we need to deal with NMIs we
 * cannot fully serialize things.
 *
 * We only publish the head (and generate a wakeup) when the outer-most
 * event completes.
 */
static void perf_output_get_handle(struct perf_output_handle *handle)
{
	struct ring_buffer *rb = handle->rb;

	preempt_disable();
	local_inc(&rb->nest);
	handle->wakeup = local_read(&rb->wakeup);
}

static void perf_output_put_handle(struct perf_output_handle *handle)
{
	struct ring_buffer *rb = handle->rb;
	unsigned long head;

again:
	head = local_read(&rb->head);

	/*
	 * IRQ/NMI can happen here, which means we can miss a head update.
	 */

	if (!local_dec_and_test(&rb->nest))
		goto out;

	/*
	 * Publish the known good head. Rely on the full barrier implied
	 * by atomic_dec_and_test() order the rb->head read and this
	 * write.
	 */
	rb->user_page->data_head = head;

	/*
	 * Now check if we missed an update, rely on the (compiler)
	 * barrier in atomic_dec_and_test() to re-read rb->head.
	 */
	if (unlikely(head != local_read(&rb->head))) {
		local_inc(&rb->nest);
		goto again;
	}

	if (handle->wakeup != local_read(&rb->wakeup))
		perf_output_wakeup(handle);

out:
	preempt_enable();
}

int perf_output_begin(struct perf_output_handle *handle,
		      struct perf_event *event, unsigned int size)
{
	struct ring_buffer *rb;
	unsigned long tail, offset, head;
	int have_lost;
	struct perf_sample_data sample_data;
	struct {
		struct perf_event_header header;
		u64			 id;
		u64			 lost;
	} lost_event;

	rcu_read_lock();
	/*
	 * For inherited events we send all the output towards the parent.
	 */
	if (event->parent)
		event = event->parent;

	rb = rcu_dereference(event->rb);
	if (!rb)
		goto out;

	handle->rb	= rb;
	handle->event	= event;

	if (!rb->nr_pages)
		goto out;

	have_lost = local_read(&rb->lost);
	if (have_lost) {
		lost_event.header.size = sizeof(lost_event);
		perf_event_header__init_id(&lost_event.header, &sample_data,
					   event);
		size += lost_event.header.size;
	}

	perf_output_get_handle(handle);

	do {
		/*
		 * Userspace could choose to issue a mb() before updating the
		 * tail pointer. So that all reads will be completed before the
		 * write is issued.
		 */
		tail = ACCESS_ONCE(rb->user_page->data_tail);
		smp_rmb();
		offset = head = local_read(&rb->head);
		head += size;
		if (unlikely(!perf_output_space(rb, tail, offset, head)))
			goto fail;
	} while (local_cmpxchg(&rb->head, offset, head) != offset);

	if (head - local_read(&rb->wakeup) > rb->watermark)
		local_add(rb->watermark, &rb->wakeup);

	handle->page = offset >> (PAGE_SHIFT + page_order(rb));
	handle->page &= rb->nr_pages - 1;
	handle->size = offset & ((PAGE_SIZE << page_order(rb)) - 1);
	handle->addr = rb->data_pages[handle->page];
	handle->addr += handle->size;
	handle->size = (PAGE_SIZE << page_order(rb)) - handle->size;

	if (have_lost) {
		lost_event.header.type = PERF_RECORD_LOST;
		lost_event.header.misc = 0;
		lost_event.id          = event->id;
		lost_event.lost        = local_xchg(&rb->lost, 0);

		perf_output_put(handle, lost_event);
		perf_event__output_id_sample(event, handle, &sample_data);
	}

	return 0;

fail:
	local_inc(&rb->lost);
	perf_output_put_handle(handle);
out:
	rcu_read_unlock();

	return -ENOSPC;
}

unsigned int perf_output_copy(struct perf_output_handle *handle,
		      const void *buf, unsigned int len)
{
	return __output_copy(handle, buf, len);
}

unsigned int perf_output_skip(struct perf_output_handle *handle,
			      unsigned int len)
{
	return __output_skip(handle, NULL, len);
}

void perf_output_end(struct perf_output_handle *handle)
{
	perf_output_put_handle(handle);
	rcu_read_unlock();
}

static void
ring_buffer_init(struct ring_buffer *rb, long watermark, int flags)
{
	long max_size = perf_data_size(rb);

	if (watermark)
		rb->watermark = min(max_size, watermark);

	if (!rb->watermark)
		rb->watermark = max_size / 2;

	if (flags & RING_BUFFER_WRITABLE)
		rb->overwrite = 0;
	else
		rb->overwrite = 1;

	atomic_set(&rb->refcount, 1);

	INIT_LIST_HEAD(&rb->event_list);
	spin_lock_init(&rb->event_lock);
}

#ifndef CONFIG_PERF_USE_VMALLOC

/*
 * Back perf_mmap() with regular GFP_KERNEL-0 pages.
 */

struct page *
perf_mmap_to_page(struct ring_buffer *rb, unsigned long pgoff)
{
	if (pgoff > rb->nr_pages)
		return NULL;

	if (pgoff == 0)
		return virt_to_page(rb->user_page);

	return virt_to_page(rb->data_pages[pgoff - 1]);
}

static void *perf_mmap_alloc_page(int cpu)
{
	struct page *page;
	int node;

	node = (cpu == -1) ? cpu : cpu_to_node(cpu);
	page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0);
	if (!page)
		return NULL;

	return page_address(page);
}

struct ring_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags)
{
	struct ring_buffer *rb;
	unsigned long size;
	int i;

	size = sizeof(struct ring_buffer);
	size += nr_pages * sizeof(void *);

	rb = kzalloc(size, GFP_KERNEL);
	if (!rb)
		goto fail;

	rb->user_page = perf_mmap_alloc_page(cpu);
	if (!rb->user_page)
		goto fail_user_page;

	for (i = 0; i < nr_pages; i++) {
		rb->data_pages[i] = perf_mmap_alloc_page(cpu);
		if (!rb->data_pages[i])
			goto fail_data_pages;
	}

	rb->nr_pages = nr_pages;

	ring_buffer_init(rb, watermark, flags);

	return rb;

fail_data_pages:
	for (i--; i >= 0; i--)
		free_page((unsigned long)rb->data_pages[i]);

	free_page((unsigned long)rb->user_page);

fail_user_page:
	kfree(rb);

fail:
	return NULL;
}

static void perf_mmap_free_page(unsigned long addr)
{
	struct page *page = virt_to_page((void *)addr);

	page->mapping = NULL;
	__free_page(page);
}

void rb_free(struct ring_buffer *rb)
{
	int i;

	perf_mmap_free_page((unsigned long)rb->user_page);
	for (i = 0; i < rb->nr_pages; i++)
		perf_mmap_free_page((unsigned long)rb->data_pages[i]);
	kfree(rb);
}

#else

struct page *
perf_mmap_to_page(struct ring_buffer *rb, unsigned long pgoff)
{
	if (pgoff > (1UL << page_order(rb)))
		return NULL;

	return vmalloc_to_page((void *)rb->user_page + pgoff * PAGE_SIZE);
}

static void perf_mmap_unmark_page(void *addr)
{
	struct page *page = vmalloc_to_page(addr);

	page->mapping = NULL;
}

static void rb_free_work(struct work_struct *work)
{
	struct ring_buffer *rb;
	void *base;
	int i, nr;

	rb = container_of(work, struct ring_buffer, work);
	nr = 1 << page_order(rb);

	base = rb->user_page;
	for (i = 0; i < nr + 1; i++)
		perf_mmap_unmark_page(base + (i * PAGE_SIZE));

	vfree(base);
	kfree(rb);
}

void rb_free(struct ring_buffer *rb)
{
	schedule_work(&rb->work);
}

struct ring_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags)
{
	struct ring_buffer *rb;
	unsigned long size;
	void *all_buf;

	size = sizeof(struct ring_buffer);
	size += sizeof(void *);

	rb = kzalloc(size, GFP_KERNEL);
	if (!rb)
		goto fail;

	INIT_WORK(&rb->work, rb_free_work);

	all_buf = vmalloc_user((nr_pages + 1) * PAGE_SIZE);
	if (!all_buf)
		goto fail_all_buf;

	rb->user_page = all_buf;
	rb->data_pages[0] = all_buf + PAGE_SIZE;
	rb->page_order = ilog2(nr_pages);
	rb->nr_pages = 1;

	ring_buffer_init(rb, watermark, flags);

	return rb;

fail_all_buf:
	kfree(rb);

fail:
	return NULL;
}

#endif
Commit	Line	Data
76369139 FW	1	/*
	2	* Performance events ring-buffer code:
	3	*
	4	* Copyright (C) 2008 Thomas Gleixner <tglx@linutronix.de>
	5	* Copyright (C) 2008-2011 Red Hat, Inc., Ingo Molnar
	6	* Copyright (C) 2008-2011 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
d36b6910	7	* Copyright © 2009 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
76369139 FW	8	*
	9	* For licensing details see kernel-base/COPYING
	10	*/
	11
	12	#include <linux/perf_event.h>
	13	#include <linux/vmalloc.h>
	14	#include <linux/slab.h>
	15
	16	#include "internal.h"
	17
	18	static bool perf_output_space(struct ring_buffer *rb, unsigned long tail,
	19	unsigned long offset, unsigned long head)
	20	{
dd9c086d SE	21	unsigned long sz = perf_data_size(rb);
dd9c086d SE	22	unsigned long mask = sz - 1;
76369139	23
dd9c086d SE	24	/*
	25	* check if user-writable
	26	* overwrite : over-write its own tail
	27	* !overwrite: buffer possibly drops events.
	28	*/
	29	if (rb->overwrite)
76369139 FW	30	return true;
76369139 FW	31
dd9c086d SE	32	/*
	33	* verify that payload is not bigger than buffer
	34	* otherwise masking logic may fail to detect
	35	* the "not enough space" condition
	36	*/
	37	if ((head - offset) > sz)
	38	return false;
76369139 FW	39
	40	offset = (offset - tail) & mask;
	41	head = (head - tail) & mask;
	42
	43	if ((int)(head - offset) < 0)
	44	return false;
	45
	46	return true;
	47	}
	48
	49	static void perf_output_wakeup(struct perf_output_handle *handle)
	50	{
	51	atomic_set(&handle->rb->poll, POLL_IN);
	52
a8b0ca17 PZ	53	handle->event->pending_wakeup = 1;
a8b0ca17 PZ	54	irq_work_queue(&handle->event->pending);
76369139 FW	55	}
	56
	57	/*
	58	* We need to ensure a later event_id doesn't publish a head when a former
	59	* event isn't done writing. However since we need to deal with NMIs we
	60	* cannot fully serialize things.
	61	*
	62	* We only publish the head (and generate a wakeup) when the outer-most
	63	* event completes.
	64	*/
	65	static void perf_output_get_handle(struct perf_output_handle *handle)
	66	{
	67	struct ring_buffer *rb = handle->rb;
	68
	69	preempt_disable();
	70	local_inc(&rb->nest);
	71	handle->wakeup = local_read(&rb->wakeup);
	72	}
	73
	74	static void perf_output_put_handle(struct perf_output_handle *handle)
	75	{
	76	struct ring_buffer *rb = handle->rb;
	77	unsigned long head;
	78
	79	again:
	80	head = local_read(&rb->head);
	81
	82	/*
	83	* IRQ/NMI can happen here, which means we can miss a head update.
	84	*/
	85
	86	if (!local_dec_and_test(&rb->nest))
	87	goto out;
	88
	89	/*
	90	* Publish the known good head. Rely on the full barrier implied
	91	* by atomic_dec_and_test() order the rb->head read and this
	92	* write.
	93	*/
	94	rb->user_page->data_head = head;
	95
	96	/*
	97	* Now check if we missed an update, rely on the (compiler)
	98	* barrier in atomic_dec_and_test() to re-read rb->head.
	99	*/
	100	if (unlikely(head != local_read(&rb->head))) {
	101	local_inc(&rb->nest);
	102	goto again;
	103	}
	104
	105	if (handle->wakeup != local_read(&rb->wakeup))
	106	perf_output_wakeup(handle);
	107
	108	out:
	109	preempt_enable();
	110	}
	111
	112	int perf_output_begin(struct perf_output_handle *handle,
a7ac67ea	113	struct perf_event *event, unsigned int size)
76369139 FW	114	{
	115	struct ring_buffer *rb;
	116	unsigned long tail, offset, head;
	117	int have_lost;
	118	struct perf_sample_data sample_data;
	119	struct {
	120	struct perf_event_header header;
	121	u64 id;
	122	u64 lost;
	123	} lost_event;
	124
	125	rcu_read_lock();
	126	/*
	127	* For inherited events we send all the output towards the parent.
	128	*/
	129	if (event->parent)
	130	event = event->parent;
	131
	132	rb = rcu_dereference(event->rb);
	133	if (!rb)
	134	goto out;
	135
	136	handle->rb = rb;
	137	handle->event = event;
76369139 FW	138
	139	if (!rb->nr_pages)
	140	goto out;
	141
	142	have_lost = local_read(&rb->lost);
	143	if (have_lost) {
	144	lost_event.header.size = sizeof(lost_event);
	145	perf_event_header__init_id(&lost_event.header, &sample_data,
	146	event);
	147	size += lost_event.header.size;
	148	}
	149
	150	perf_output_get_handle(handle);
	151
	152	do {
	153	/*
	154	* Userspace could choose to issue a mb() before updating the
	155	* tail pointer. So that all reads will be completed before the
	156	* write is issued.
	157	*/
	158	tail = ACCESS_ONCE(rb->user_page->data_tail);
	159	smp_rmb();
	160	offset = head = local_read(&rb->head);
	161	head += size;
	162	if (unlikely(!perf_output_space(rb, tail, offset, head)))
	163	goto fail;
	164	} while (local_cmpxchg(&rb->head, offset, head) != offset);
	165
	166	if (head - local_read(&rb->wakeup) > rb->watermark)
	167	local_add(rb->watermark, &rb->wakeup);
	168
	169	handle->page = offset >> (PAGE_SHIFT + page_order(rb));
	170	handle->page &= rb->nr_pages - 1;
	171	handle->size = offset & ((PAGE_SIZE << page_order(rb)) - 1);
	172	handle->addr = rb->data_pages[handle->page];
	173	handle->addr += handle->size;
	174	handle->size = (PAGE_SIZE << page_order(rb)) - handle->size;
	175
	176	if (have_lost) {
	177	lost_event.header.type = PERF_RECORD_LOST;
	178	lost_event.header.misc = 0;
	179	lost_event.id = event->id;
	180	lost_event.lost = local_xchg(&rb->lost, 0);
	181
	182	perf_output_put(handle, lost_event);
	183	perf_event__output_id_sample(event, handle, &sample_data);
	184	}
	185
	186	return 0;
	187
	188	fail:
	189	local_inc(&rb->lost);
	190	perf_output_put_handle(handle);
	191	out:
	192	rcu_read_unlock();
	193
	194	return -ENOSPC;
	195	}
	196
91d7753a	197	unsigned int perf_output_copy(struct perf_output_handle *handle,
76369139 FW	198	const void *buf, unsigned int len)
76369139 FW	199	{
91d7753a	200	return __output_copy(handle, buf, len);
76369139 FW	201	}
76369139 FW	202
5685e0ff JO	203	unsigned int perf_output_skip(struct perf_output_handle *handle,
	204	unsigned int len)
	205	{
	206	return __output_skip(handle, NULL, len);
	207	}
	208
76369139 FW	209	void perf_output_end(struct perf_output_handle *handle)
76369139 FW	210	{
76369139 FW	211	perf_output_put_handle(handle);
	212	rcu_read_unlock();
	213	}
	214
	215	static void
	216	ring_buffer_init(struct ring_buffer *rb, long watermark, int flags)
	217	{
	218	long max_size = perf_data_size(rb);
	219
	220	if (watermark)
	221	rb->watermark = min(max_size, watermark);
	222
	223	if (!rb->watermark)
	224	rb->watermark = max_size / 2;
	225
	226	if (flags & RING_BUFFER_WRITABLE)
dd9c086d SE	227	rb->overwrite = 0;
	228	else
	229	rb->overwrite = 1;
76369139 FW	230
76369139 FW	231	atomic_set(&rb->refcount, 1);
10c6db11 PZ	232
	233	INIT_LIST_HEAD(&rb->event_list);
	234	spin_lock_init(&rb->event_lock);
76369139 FW	235	}
	236
	237	#ifndef CONFIG_PERF_USE_VMALLOC
	238
	239	/*
	240	* Back perf_mmap() with regular GFP_KERNEL-0 pages.
	241	*/
	242
	243	struct page *
	244	perf_mmap_to_page(struct ring_buffer *rb, unsigned long pgoff)
	245	{
	246	if (pgoff > rb->nr_pages)
	247	return NULL;
	248
	249	if (pgoff == 0)
	250	return virt_to_page(rb->user_page);
	251
	252	return virt_to_page(rb->data_pages[pgoff - 1]);
	253	}
	254
	255	static void *perf_mmap_alloc_page(int cpu)
	256	{
	257	struct page *page;
	258	int node;
	259
	260	node = (cpu == -1) ? cpu : cpu_to_node(cpu);
	261	page = alloc_pages_node(node, GFP_KERNEL \| __GFP_ZERO, 0);
	262	if (!page)
	263	return NULL;
	264
	265	return page_address(page);
	266	}
	267
	268	struct ring_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags)
	269	{
	270	struct ring_buffer *rb;
	271	unsigned long size;
	272	int i;
	273
	274	size = sizeof(struct ring_buffer);
	275	size += nr_pages * sizeof(void *);
	276
	277	rb = kzalloc(size, GFP_KERNEL);
	278	if (!rb)
	279	goto fail;
	280
	281	rb->user_page = perf_mmap_alloc_page(cpu);
	282	if (!rb->user_page)
	283	goto fail_user_page;
	284
	285	for (i = 0; i < nr_pages; i++) {
	286	rb->data_pages[i] = perf_mmap_alloc_page(cpu);
	287	if (!rb->data_pages[i])
	288	goto fail_data_pages;
	289	}
	290
	291	rb->nr_pages = nr_pages;
	292
	293	ring_buffer_init(rb, watermark, flags);
	294
	295	return rb;
	296
	297	fail_data_pages:
	298	for (i--; i >= 0; i--)
299	free_page((unsigned long)rb->data_pages[i]);
300
301	free_page((unsigned long)rb->user_page);
302
303	fail_user_page:
304	kfree(rb);
305
306	fail:
307	return NULL;
308	}
309
310	static void perf_mmap_free_page(unsigned long addr)
311	{
312	struct page page = virt_to_page((void )addr);
313
314	page->mapping = NULL;
315	__free_page(page);
316	}
317
318	void rb_free(struct ring_buffer *rb)
319	{
320	int i;
321
322	perf_mmap_free_page((unsigned long)rb->user_page);
323	for (i = 0; i < rb->nr_pages; i++)
324	perf_mmap_free_page((unsigned long)rb->data_pages[i]);
325	kfree(rb);
326	}
327
328	#else
329
330	struct page *
331	perf_mmap_to_page(struct ring_buffer *rb, unsigned long pgoff)
332	{
333	if (pgoff > (1UL << page_order(rb)))
334	return NULL;
335
336	return vmalloc_to_page((void )rb->user_page + pgoff PAGE_SIZE);
337	}
338
339	static void perf_mmap_unmark_page(void *addr)
340	{
341	struct page *page = vmalloc_to_page(addr);
342
343	page->mapping = NULL;
344	}
345
346	static void rb_free_work(struct work_struct *work)
347	{
348	struct ring_buffer *rb;
349	void *base;
350	int i, nr;
351
352	rb = container_of(work, struct ring_buffer, work);
353	nr = 1 << page_order(rb);
354
355	base = rb->user_page;
356	for (i = 0; i < nr + 1; i++)
357	perf_mmap_unmark_page(base + (i * PAGE_SIZE));
358
359	vfree(base);
360	kfree(rb);
361	}
362
363	void rb_free(struct ring_buffer *rb)
364	{
365	schedule_work(&rb->work);
366	}
367
368	struct ring_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags)
369	{
370	struct ring_buffer *rb;
371	unsigned long size;
372	void *all_buf;
373
374	size = sizeof(struct ring_buffer);
375	size += sizeof(void *);
376
377	rb = kzalloc(size, GFP_KERNEL);
378	if (!rb)
379	goto fail;
380
381	INIT_WORK(&rb->work, rb_free_work);
382
383	all_buf = vmalloc_user((nr_pages + 1) * PAGE_SIZE);
384	if (!all_buf)
385	goto fail_all_buf;
386
387	rb->user_page = all_buf;
388	rb->data_pages[0] = all_buf + PAGE_SIZE;
389	rb->page_order = ilog2(nr_pages);
390	rb->nr_pages = 1;
391
392	ring_buffer_init(rb, watermark, flags);
393
394	return rb;
395
396	fail_all_buf:
397	kfree(rb);
398
399	fail:
400	return NULL;
401	}
402
403	#endif