drivers/hwtracing/coresight/coresight-etm-perf.c - arm/linux - Git at Google

 /*
  * Copyright(C) 2015 Linaro Limited. All rights reserved.
  * Author: Mathieu Poirier <mathieu.poirier@linaro.org>
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 as published by
  * the Free Software Foundation.
  *
  * This program is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  * more details.
  *
  * You should have received a copy of the GNU General Public License along with
  * this program.  If not, see <http://www.gnu.org/licenses/>.
  */

 #include <linux/coresight.h>
 #include <linux/coresight-pmu.h>
 #include <linux/cpumask.h>
 #include <linux/device.h>
 #include <linux/list.h>
 #include <linux/mm.h>
 #include <linux/init.h>
 #include <linux/perf_event.h>
 #include <linux/slab.h>
 #include <linux/types.h>
 #include <linux/workqueue.h>

 #include "coresight-etm-perf.h"
 #include "coresight-priv.h"

 static struct pmu etm_pmu;
 static bool etm_perf_up;

 /**
  * struct etm_event_data - Coresight specifics associated to an event
  * @work:		Handle to free allocated memory outside IRQ context.
  * @mask:		Hold the CPU(s) this event was set for.
  * @snk_config:		The sink configuration.
  * @path:		An array of path, each slot for one CPU.
  */
 struct etm_event_data {
 	struct work_struct work;
 	cpumask_t mask;
 	void *snk_config;
 	struct list_head **path;
 };

 static DEFINE_PER_CPU(struct perf_output_handle, ctx_handle);
 static DEFINE_PER_CPU(struct coresight_device *, csdev_src);

 /* ETMv3.5/PTM's ETMCR is 'config' */
 PMU_FORMAT_ATTR(cycacc,		"config:" __stringify(ETM_OPT_CYCACC));
 PMU_FORMAT_ATTR(timestamp,	"config:" __stringify(ETM_OPT_TS));
 PMU_FORMAT_ATTR(retstack,	"config:" __stringify(ETM_OPT_RETSTK));

 static struct attribute *etm_config_formats_attr[] = {
 	&format_attr_cycacc.attr,
 	&format_attr_timestamp.attr,
 	&format_attr_retstack.attr,
 	NULL,
 };

 static const struct attribute_group etm_pmu_format_group = {
 	.name   = "format",
 	.attrs  = etm_config_formats_attr,
 };

 static const struct attribute_group *etm_pmu_attr_groups[] = {
 	&etm_pmu_format_group,
 	NULL,
 };

 static void etm_event_read(struct perf_event *event) {}

 static int etm_addr_filters_alloc(struct perf_event *event)
 {
 	struct etm_filters *filters;
 	int node = event->cpu == -1 ? -1 : cpu_to_node(event->cpu);

 	filters = kzalloc_node(sizeof(struct etm_filters), GFP_KERNEL, node);
 	if (!filters)
 		return -ENOMEM;

 	if (event->parent)
 		memcpy(filters, event->parent->hw.addr_filters,
 		       sizeof(*filters));

 	event->hw.addr_filters = filters;

 	return 0;
 }

 static void etm_event_destroy(struct perf_event *event)
 {
 	kfree(event->hw.addr_filters);
 	event->hw.addr_filters = NULL;
 }

 static int etm_event_init(struct perf_event *event)
 {
 	int ret = 0;

 	if (event->attr.type != etm_pmu.type) {
 		ret = -ENOENT;
 		goto out;
 	}

 	ret = etm_addr_filters_alloc(event);
 	if (ret)
 		goto out;

 	event->destroy = etm_event_destroy;
 out:
 	return ret;
 }

 static void free_event_data(struct work_struct *work)
 {
 	int cpu;
 	cpumask_t *mask;
 	struct etm_event_data *event_data;
 	struct coresight_device *sink;

 	event_data = container_of(work, struct etm_event_data, work);
 	mask = &event_data->mask;
 	/*
 	 * First deal with the sink configuration.  See comment in
 	 * etm_setup_aux() about why we take the first available path.
 	 */
 	if (event_data->snk_config) {
 		cpu = cpumask_first(mask);
 		sink = coresight_get_sink(event_data->path[cpu]);
 		if (sink_ops(sink)->free_buffer)
 			sink_ops(sink)->free_buffer(event_data->snk_config);
 	}

 	for_each_cpu(cpu, mask) {
 		if (!(IS_ERR_OR_NULL(event_data->path[cpu])))
 			coresight_release_path(event_data->path[cpu]);
 	}

 	kfree(event_data->path);
 	kfree(event_data);
 }

 static void *alloc_event_data(int cpu)
 {
 	int size;
 	cpumask_t *mask;
 	struct etm_event_data *event_data;

 	/* First get memory for the session's data */
 	event_data = kzalloc(sizeof(struct etm_event_data), GFP_KERNEL);
 	if (!event_data)
 		return NULL;

 	/* Make sure nothing disappears under us */
 	get_online_cpus();
 	size = num_online_cpus();

 	mask = &event_data->mask;
 	if (cpu != -1)
 		cpumask_set_cpu(cpu, mask);
 	else
 		cpumask_copy(mask, cpu_online_mask);
 	put_online_cpus();

 	/*
 	 * Each CPU has a single path between source and destination.  As such
 	 * allocate an array using CPU numbers as indexes.  That way a path
 	 * for any CPU can easily be accessed at any given time.  We proceed
 	 * the same way for sessions involving a single CPU.  The cost of
 	 * unused memory when dealing with single CPU trace scenarios is small
 	 * compared to the cost of searching through an optimized array.
 	 */
 	event_data->path = kcalloc(size,
 				   sizeof(struct list_head *), GFP_KERNEL);
 	if (!event_data->path) {
 		kfree(event_data);
 		return NULL;
 	}

 	return event_data;
 }

 static void etm_free_aux(void *data)
 {
 	struct etm_event_data *event_data = data;

 	schedule_work(&event_data->work);
 }

 static void *etm_setup_aux(int event_cpu, void **pages,
 			   int nr_pages, bool overwrite)
 {
 	int cpu;
 	cpumask_t *mask;
 	struct coresight_device *sink;
 	struct etm_event_data *event_data = NULL;

 	event_data = alloc_event_data(event_cpu);
 	if (!event_data)
 		return NULL;
 	INIT_WORK(&event_data->work, free_event_data);

 	/*
 	 * In theory nothing prevent tracers in a trace session from being
 	 * associated with different sinks, nor having a sink per tracer.  But
 	 * until we have HW with this kind of topology we need to assume tracers
 	 * in a trace session are using the same sink.  Therefore go through
 	 * the coresight bus and pick the first enabled sink.
 	 *
 	 * When operated from sysFS users are responsible to enable the sink
 	 * while from perf, the perf tools will do it based on the choice made
 	 * on the cmd line.  As such the "enable_sink" flag in sysFS is reset.
 	 */
 	sink = coresight_get_enabled_sink(true);
 	if (!sink)
 		goto err;

 	mask = &event_data->mask;

 	/* Setup the path for each CPU in a trace session */
 	for_each_cpu(cpu, mask) {
 		struct coresight_device *csdev;

 		csdev = per_cpu(csdev_src, cpu);
 		if (!csdev)
 			goto err;

 		/*
 		 * Building a path doesn't enable it, it simply builds a
 		 * list of devices from source to sink that can be
 		 * referenced later when the path is actually needed.
 		 */
 		event_data->path[cpu] = coresight_build_path(csdev, sink);
 		if (IS_ERR(event_data->path[cpu]))
 			goto err;
 	}

 	if (!sink_ops(sink)->alloc_buffer)
 		goto err;

 	cpu = cpumask_first(mask);
 	/* Get the AUX specific data from the sink buffer */
 	event_data->snk_config =
 			sink_ops(sink)->alloc_buffer(sink, cpu, pages,
 						     nr_pages, overwrite);
 	if (!event_data->snk_config)
 		goto err;

 out:
 	return event_data;

 err:
 	etm_free_aux(event_data);
 	event_data = NULL;
 	goto out;
 }

 static void etm_event_start(struct perf_event *event, int flags)
 {
 	int cpu = smp_processor_id();
 	struct etm_event_data *event_data;
 	struct perf_output_handle *handle = this_cpu_ptr(&ctx_handle);
 	struct coresight_device *sink, *csdev = per_cpu(csdev_src, cpu);

 	if (!csdev)
 		goto fail;

 	/*
 	 * Deal with the ring buffer API and get a handle on the
 	 * session's information.
 	 */
 	event_data = perf_aux_output_begin(handle, event);
 	if (!event_data)
 		goto fail;

 	/* We need a sink, no need to continue without one */
 	sink = coresight_get_sink(event_data->path[cpu]);
 	if (WARN_ON_ONCE(!sink || !sink_ops(sink)->set_buffer))
 		goto fail_end_stop;

 	/* Configure the sink */
 	if (sink_ops(sink)->set_buffer(sink, handle,
 				       event_data->snk_config))
 		goto fail_end_stop;

 	/* Nothing will happen without a path */
 	if (coresight_enable_path(event_data->path[cpu], CS_MODE_PERF))
 		goto fail_end_stop;

 	/* Tell the perf core the event is alive */
 	event->hw.state = 0;

 	/* Finally enable the tracer */
 	if (source_ops(csdev)->enable(csdev, event, CS_MODE_PERF))
 		goto fail_end_stop;

 out:
 	return;

 fail_end_stop:
 	perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
 	perf_aux_output_end(handle, 0);
 fail:
 	event->hw.state = PERF_HES_STOPPED;
 	goto out;
 }

 static void etm_event_stop(struct perf_event *event, int mode)
 {
 	int cpu = smp_processor_id();
 	unsigned long size;
 	struct coresight_device *sink, *csdev = per_cpu(csdev_src, cpu);
 	struct perf_output_handle *handle = this_cpu_ptr(&ctx_handle);
 	struct etm_event_data *event_data = perf_get_aux(handle);

 	if (event->hw.state == PERF_HES_STOPPED)
 		return;

 	if (!csdev)
 		return;

 	sink = coresight_get_sink(event_data->path[cpu]);
 	if (!sink)
 		return;

 	/* stop tracer */
 	source_ops(csdev)->disable(csdev, event);

 	/* tell the core */
 	event->hw.state = PERF_HES_STOPPED;

 	if (mode & PERF_EF_UPDATE) {
 		if (WARN_ON_ONCE(handle->event != event))
 			return;

 		/* update trace information */
 		if (!sink_ops(sink)->update_buffer)
 			return;

 		sink_ops(sink)->update_buffer(sink, handle,
 					      event_data->snk_config);

 		if (!sink_ops(sink)->reset_buffer)
 			return;

 		size = sink_ops(sink)->reset_buffer(sink, handle,
 						    event_data->snk_config);

 		perf_aux_output_end(handle, size);
 	}

 	/* Disabling the path make its elements available to other sessions */
 	coresight_disable_path(event_data->path[cpu]);
 }

 static int etm_event_add(struct perf_event *event, int mode)
 {
 	int ret = 0;
 	struct hw_perf_event *hwc = &event->hw;

 	if (mode & PERF_EF_START) {
 		etm_event_start(event, 0);
 		if (hwc->state & PERF_HES_STOPPED)
 			ret = -EINVAL;
 	} else {
 		hwc->state = PERF_HES_STOPPED;
 	}

 	return ret;
 }

 static void etm_event_del(struct perf_event *event, int mode)
 {
 	etm_event_stop(event, PERF_EF_UPDATE);
 }

 static int etm_addr_filters_validate(struct list_head *filters)
 {
 	bool range = false, address = false;
 	int index = 0;
 	struct perf_addr_filter *filter;

 	list_for_each_entry(filter, filters, entry) {
 		/*
 		 * No need to go further if there's no more
 		 * room for filters.
 		 */
 		if (++index > ETM_ADDR_CMP_MAX)
 			return -EOPNOTSUPP;

 		/*
 		 * As taken from the struct perf_addr_filter documentation:
 		 *	@range:	1: range, 0: address
 		 *
 		 * At this time we don't allow range and start/stop filtering
 		 * to cohabitate, they have to be mutually exclusive.
 		 */
 		if ((filter->range == 1) && address)
 			return -EOPNOTSUPP;

 		if ((filter->range == 0) && range)
 			return -EOPNOTSUPP;

 		/*
 		 * For range filtering, the second address in the address
 		 * range comparator needs to be higher than the first.
 		 * Invalid otherwise.
 		 */
 		if (filter->range && filter->size == 0)
 			return -EINVAL;

 		/*
 		 * Everything checks out with this filter, record what we've
 		 * received before moving on to the next one.
 		 */
 		if (filter->range)
 			range = true;
 		else
 			address = true;
 	}

 	return 0;
 }

 static void etm_addr_filters_sync(struct perf_event *event)
 {
 	struct perf_addr_filters_head *head = perf_event_addr_filters(event);
 	unsigned long start, stop, *offs = event->addr_filters_offs;
 	struct etm_filters *filters = event->hw.addr_filters;
 	struct etm_filter *etm_filter;
 	struct perf_addr_filter *filter;
 	int i = 0;

 	list_for_each_entry(filter, &head->list, entry) {
 		start = filter->offset + offs[i];
 		stop = start + filter->size;
 		etm_filter = &filters->etm_filter[i];

 		if (filter->range == 1) {
 			etm_filter->start_addr = start;
 			etm_filter->stop_addr = stop;
 			etm_filter->type = ETM_ADDR_TYPE_RANGE;
 		} else {
 			if (filter->filter == 1) {
 				etm_filter->start_addr = start;
 				etm_filter->type = ETM_ADDR_TYPE_START;
 			} else {
 				etm_filter->stop_addr = stop;
 				etm_filter->type = ETM_ADDR_TYPE_STOP;
 			}
 		}
 		i++;
 	}

 	filters->nr_filters = i;
 }

 int etm_perf_symlink(struct coresight_device *csdev, bool link)
 {
 	char entry[sizeof("cpu9999999")];
 	int ret = 0, cpu = source_ops(csdev)->cpu_id(csdev);
 	struct device *pmu_dev = etm_pmu.dev;
 	struct device *cs_dev = &csdev->dev;

 	sprintf(entry, "cpu%d", cpu);

 	if (!etm_perf_up)
 		return -EPROBE_DEFER;

 	if (link) {
 		ret = sysfs_create_link(&pmu_dev->kobj, &cs_dev->kobj, entry);
 		if (ret)
 			return ret;
 		per_cpu(csdev_src, cpu) = csdev;
 	} else {
 		sysfs_remove_link(&pmu_dev->kobj, entry);
 		per_cpu(csdev_src, cpu) = NULL;
 	}

 	return 0;
 }

 static int __init etm_perf_init(void)
 {
 	int ret;

 	etm_pmu.capabilities		= PERF_PMU_CAP_EXCLUSIVE;

 	etm_pmu.attr_groups		= etm_pmu_attr_groups;
 	etm_pmu.task_ctx_nr		= perf_sw_context;
 	etm_pmu.read			= etm_event_read;
 	etm_pmu.event_init		= etm_event_init;
 	etm_pmu.setup_aux		= etm_setup_aux;
 	etm_pmu.free_aux		= etm_free_aux;
 	etm_pmu.start			= etm_event_start;
 	etm_pmu.stop			= etm_event_stop;
 	etm_pmu.add			= etm_event_add;
 	etm_pmu.del			= etm_event_del;
 	etm_pmu.addr_filters_sync	= etm_addr_filters_sync;
 	etm_pmu.addr_filters_validate	= etm_addr_filters_validate;
 	etm_pmu.nr_addr_filters		= ETM_ADDR_CMP_MAX;

 	ret = perf_pmu_register(&etm_pmu, CORESIGHT_ETM_PMU_NAME, -1);
 	if (ret == 0)
 		etm_perf_up = true;

 	return ret;
 }
 device_initcall(etm_perf_init);
	/*
	* Copyright(C) 2015 Linaro Limited. All rights reserved.
	* Author: Mathieu Poirier <mathieu.poirier@linaro.org>
	*
	* This program is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 as published by
	* the Free Software Foundation.
	*
	* This program is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
	* more details.
	*
	* You should have received a copy of the GNU General Public License along with
	* this program. If not, see <http://www.gnu.org/licenses/>.
	*/

	#include <linux/coresight.h>
	#include <linux/coresight-pmu.h>
	#include <linux/cpumask.h>
	#include <linux/device.h>
	#include <linux/list.h>
	#include <linux/mm.h>
	#include <linux/init.h>
	#include <linux/perf_event.h>
	#include <linux/slab.h>
	#include <linux/types.h>
	#include <linux/workqueue.h>

	#include "coresight-etm-perf.h"
	#include "coresight-priv.h"

	static struct pmu etm_pmu;
	static bool etm_perf_up;

	/**
	* struct etm_event_data - Coresight specifics associated to an event
	* @work: Handle to free allocated memory outside IRQ context.
	* @mask: Hold the CPU(s) this event was set for.
	* @snk_config: The sink configuration.
	* @path: An array of path, each slot for one CPU.
	*/
	struct etm_event_data {
	struct work_struct work;
	cpumask_t mask;
	void *snk_config;
	struct list_head **path;
	};

	static DEFINE_PER_CPU(struct perf_output_handle, ctx_handle);
	static DEFINE_PER_CPU(struct coresight_device *, csdev_src);

	/* ETMv3.5/PTM's ETMCR is 'config' */
	PMU_FORMAT_ATTR(cycacc, "config:" __stringify(ETM_OPT_CYCACC));
	PMU_FORMAT_ATTR(timestamp, "config:" __stringify(ETM_OPT_TS));
	PMU_FORMAT_ATTR(retstack, "config:" __stringify(ETM_OPT_RETSTK));

	static struct attribute *etm_config_formats_attr[] = {
	&format_attr_cycacc.attr,
	&format_attr_timestamp.attr,
	&format_attr_retstack.attr,
	NULL,
	};

	static const struct attribute_group etm_pmu_format_group = {
	.name = "format",
	.attrs = etm_config_formats_attr,
	};

	static const struct attribute_group *etm_pmu_attr_groups[] = {
	&etm_pmu_format_group,
	NULL,
	};

	static void etm_event_read(struct perf_event *event) {}

	static int etm_addr_filters_alloc(struct perf_event *event)
	{
	struct etm_filters *filters;
	int node = event->cpu == -1 ? -1 : cpu_to_node(event->cpu);

	filters = kzalloc_node(sizeof(struct etm_filters), GFP_KERNEL, node);
	if (!filters)
	return -ENOMEM;

	if (event->parent)
	memcpy(filters, event->parent->hw.addr_filters,
	sizeof(*filters));

	event->hw.addr_filters = filters;

	return 0;
	}

	static void etm_event_destroy(struct perf_event *event)
	{
	kfree(event->hw.addr_filters);
	event->hw.addr_filters = NULL;
	}

	static int etm_event_init(struct perf_event *event)
	{
	int ret = 0;

	if (event->attr.type != etm_pmu.type) {
	ret = -ENOENT;
	goto out;
	}

	ret = etm_addr_filters_alloc(event);
	if (ret)
	goto out;

	event->destroy = etm_event_destroy;
	out:
	return ret;
	}

	static void free_event_data(struct work_struct *work)
	{
	int cpu;
	cpumask_t *mask;
	struct etm_event_data *event_data;
	struct coresight_device *sink;

	event_data = container_of(work, struct etm_event_data, work);
	mask = &event_data->mask;
	/*
	* First deal with the sink configuration. See comment in
	* etm_setup_aux() about why we take the first available path.
	*/
	if (event_data->snk_config) {
	cpu = cpumask_first(mask);
	sink = coresight_get_sink(event_data->path[cpu]);
	if (sink_ops(sink)->free_buffer)
	sink_ops(sink)->free_buffer(event_data->snk_config);
	}

	for_each_cpu(cpu, mask) {
	if (!(IS_ERR_OR_NULL(event_data->path[cpu])))
	coresight_release_path(event_data->path[cpu]);
	}

	kfree(event_data->path);
	kfree(event_data);
	}

	static void *alloc_event_data(int cpu)
	{
	int size;
	cpumask_t *mask;
	struct etm_event_data *event_data;

	/* First get memory for the session's data */
	event_data = kzalloc(sizeof(struct etm_event_data), GFP_KERNEL);
	if (!event_data)
	return NULL;

	/* Make sure nothing disappears under us */
	get_online_cpus();
	size = num_online_cpus();

	mask = &event_data->mask;
	if (cpu != -1)
	cpumask_set_cpu(cpu, mask);
	else
	cpumask_copy(mask, cpu_online_mask);
	put_online_cpus();

	/*
	* Each CPU has a single path between source and destination. As such
	* allocate an array using CPU numbers as indexes. That way a path
	* for any CPU can easily be accessed at any given time. We proceed
	* the same way for sessions involving a single CPU. The cost of
	* unused memory when dealing with single CPU trace scenarios is small
	* compared to the cost of searching through an optimized array.
	*/
	event_data->path = kcalloc(size,
	sizeof(struct list_head *), GFP_KERNEL);
	if (!event_data->path) {
	kfree(event_data);
	return NULL;
	}

	return event_data;
	}

	static void etm_free_aux(void *data)
	{
	struct etm_event_data *event_data = data;

	schedule_work(&event_data->work);
	}

	static void etm_setup_aux(int event_cpu, void *pages,
	int nr_pages, bool overwrite)
	{
	int cpu;
	cpumask_t *mask;
	struct coresight_device *sink;
	struct etm_event_data *event_data = NULL;

	event_data = alloc_event_data(event_cpu);
	if (!event_data)
	return NULL;
	INIT_WORK(&event_data->work, free_event_data);

	/*
	* In theory nothing prevent tracers in a trace session from being
	* associated with different sinks, nor having a sink per tracer. But
	* until we have HW with this kind of topology we need to assume tracers
	* in a trace session are using the same sink. Therefore go through
	* the coresight bus and pick the first enabled sink.
	*
	* When operated from sysFS users are responsible to enable the sink
	* while from perf, the perf tools will do it based on the choice made
	* on the cmd line. As such the "enable_sink" flag in sysFS is reset.
	*/
	sink = coresight_get_enabled_sink(true);
	if (!sink)
	goto err;

	mask = &event_data->mask;

	/* Setup the path for each CPU in a trace session */
	for_each_cpu(cpu, mask) {
	struct coresight_device *csdev;

	csdev = per_cpu(csdev_src, cpu);
	if (!csdev)
	goto err;

	/*
	* Building a path doesn't enable it, it simply builds a
	* list of devices from source to sink that can be
	* referenced later when the path is actually needed.
	*/
	event_data->path[cpu] = coresight_build_path(csdev, sink);
	if (IS_ERR(event_data->path[cpu]))
	goto err;
	}

	if (!sink_ops(sink)->alloc_buffer)
	goto err;

	cpu = cpumask_first(mask);
	/* Get the AUX specific data from the sink buffer */
	event_data->snk_config =
	sink_ops(sink)->alloc_buffer(sink, cpu, pages,
	nr_pages, overwrite);
	if (!event_data->snk_config)
	goto err;

	out:
	return event_data;

	err:
	etm_free_aux(event_data);
	event_data = NULL;
	goto out;
	}

	static void etm_event_start(struct perf_event *event, int flags)
	{
	int cpu = smp_processor_id();
	struct etm_event_data *event_data;
	struct perf_output_handle *handle = this_cpu_ptr(&ctx_handle);
	struct coresight_device sink, csdev = per_cpu(csdev_src, cpu);

	if (!csdev)
	goto fail;

	/*
	* Deal with the ring buffer API and get a handle on the
	* session's information.
	*/
	event_data = perf_aux_output_begin(handle, event);
	if (!event_data)
	goto fail;

	/* We need a sink, no need to continue without one */
	sink = coresight_get_sink(event_data->path[cpu]);
	if (WARN_ON_ONCE(!sink \|\| !sink_ops(sink)->set_buffer))
	goto fail_end_stop;

	/* Configure the sink */
	if (sink_ops(sink)->set_buffer(sink, handle,
	event_data->snk_config))
	goto fail_end_stop;

	/* Nothing will happen without a path */
	if (coresight_enable_path(event_data->path[cpu], CS_MODE_PERF))
	goto fail_end_stop;

	/* Tell the perf core the event is alive */
	event->hw.state = 0;

	/* Finally enable the tracer */
	if (source_ops(csdev)->enable(csdev, event, CS_MODE_PERF))
	goto fail_end_stop;

	out:
	return;

	fail_end_stop:
	perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
	perf_aux_output_end(handle, 0);
	fail:
	event->hw.state = PERF_HES_STOPPED;
	goto out;
	}

	static void etm_event_stop(struct perf_event *event, int mode)
	{
	int cpu = smp_processor_id();
	unsigned long size;
	struct coresight_device sink, csdev = per_cpu(csdev_src, cpu);
	struct perf_output_handle *handle = this_cpu_ptr(&ctx_handle);
	struct etm_event_data *event_data = perf_get_aux(handle);

	if (event->hw.state == PERF_HES_STOPPED)
	return;

	if (!csdev)
	return;

	sink = coresight_get_sink(event_data->path[cpu]);
	if (!sink)
	return;

	/* stop tracer */
	source_ops(csdev)->disable(csdev, event);

	/* tell the core */
	event->hw.state = PERF_HES_STOPPED;

	if (mode & PERF_EF_UPDATE) {
	if (WARN_ON_ONCE(handle->event != event))
	return;

	/* update trace information */
	if (!sink_ops(sink)->update_buffer)
	return;

	sink_ops(sink)->update_buffer(sink, handle,
	event_data->snk_config);

	if (!sink_ops(sink)->reset_buffer)
	return;

	size = sink_ops(sink)->reset_buffer(sink, handle,
	event_data->snk_config);

	perf_aux_output_end(handle, size);
	}

	/* Disabling the path make its elements available to other sessions */
	coresight_disable_path(event_data->path[cpu]);
	}

	static int etm_event_add(struct perf_event *event, int mode)
	{
	int ret = 0;
	struct hw_perf_event *hwc = &event->hw;

	if (mode & PERF_EF_START) {
	etm_event_start(event, 0);
	if (hwc->state & PERF_HES_STOPPED)
	ret = -EINVAL;
	} else {
	hwc->state = PERF_HES_STOPPED;
	}

	return ret;
	}

	static void etm_event_del(struct perf_event *event, int mode)
	{
	etm_event_stop(event, PERF_EF_UPDATE);
	}

	static int etm_addr_filters_validate(struct list_head *filters)
	{
	bool range = false, address = false;
	int index = 0;
	struct perf_addr_filter *filter;

	list_for_each_entry(filter, filters, entry) {
	/*
	* No need to go further if there's no more
	* room for filters.
	*/
	if (++index > ETM_ADDR_CMP_MAX)
	return -EOPNOTSUPP;

	/*
	* As taken from the struct perf_addr_filter documentation:
	* @range: 1: range, 0: address
	*
	* At this time we don't allow range and start/stop filtering
	* to cohabitate, they have to be mutually exclusive.
	*/
	if ((filter->range == 1) && address)
	return -EOPNOTSUPP;

	if ((filter->range == 0) && range)
	return -EOPNOTSUPP;

	/*
	* For range filtering, the second address in the address
	* range comparator needs to be higher than the first.
	* Invalid otherwise.
	*/
	if (filter->range && filter->size == 0)
	return -EINVAL;

	/*
	* Everything checks out with this filter, record what we've
	* received before moving on to the next one.
	*/
	if (filter->range)
	range = true;
	else
	address = true;
	}

	return 0;
	}

	static void etm_addr_filters_sync(struct perf_event *event)
	{
	struct perf_addr_filters_head *head = perf_event_addr_filters(event);
	unsigned long start, stop, *offs = event->addr_filters_offs;
	struct etm_filters *filters = event->hw.addr_filters;
	struct etm_filter *etm_filter;
	struct perf_addr_filter *filter;
	int i = 0;

	list_for_each_entry(filter, &head->list, entry) {
	start = filter->offset + offs[i];
	stop = start + filter->size;
	etm_filter = &filters->etm_filter[i];

	if (filter->range == 1) {
	etm_filter->start_addr = start;
	etm_filter->stop_addr = stop;
	etm_filter->type = ETM_ADDR_TYPE_RANGE;
	} else {
	if (filter->filter == 1) {
	etm_filter->start_addr = start;
	etm_filter->type = ETM_ADDR_TYPE_START;
	} else {
	etm_filter->stop_addr = stop;
	etm_filter->type = ETM_ADDR_TYPE_STOP;
	}
	}
	i++;
	}

	filters->nr_filters = i;
	}

	int etm_perf_symlink(struct coresight_device *csdev, bool link)
	{
	char entry[sizeof("cpu9999999")];
	int ret = 0, cpu = source_ops(csdev)->cpu_id(csdev);
	struct device *pmu_dev = etm_pmu.dev;
	struct device *cs_dev = &csdev->dev;

	sprintf(entry, "cpu%d", cpu);

	if (!etm_perf_up)
	return -EPROBE_DEFER;

	if (link) {
	ret = sysfs_create_link(&pmu_dev->kobj, &cs_dev->kobj, entry);
	if (ret)
	return ret;
	per_cpu(csdev_src, cpu) = csdev;
	} else {
	sysfs_remove_link(&pmu_dev->kobj, entry);
	per_cpu(csdev_src, cpu) = NULL;
	}

	return 0;
	}

	static int __init etm_perf_init(void)
	{
	int ret;

	etm_pmu.capabilities = PERF_PMU_CAP_EXCLUSIVE;

	etm_pmu.attr_groups = etm_pmu_attr_groups;
	etm_pmu.task_ctx_nr = perf_sw_context;
	etm_pmu.read = etm_event_read;
	etm_pmu.event_init = etm_event_init;
	etm_pmu.setup_aux = etm_setup_aux;
	etm_pmu.free_aux = etm_free_aux;
	etm_pmu.start = etm_event_start;
	etm_pmu.stop = etm_event_stop;
	etm_pmu.add = etm_event_add;
	etm_pmu.del = etm_event_del;
	etm_pmu.addr_filters_sync = etm_addr_filters_sync;
	etm_pmu.addr_filters_validate = etm_addr_filters_validate;
	etm_pmu.nr_addr_filters = ETM_ADDR_CMP_MAX;

	ret = perf_pmu_register(&etm_pmu, CORESIGHT_ETM_PMU_NAME, -1);
	if (ret == 0)
	etm_perf_up = true;

	return ret;
	}
	device_initcall(etm_perf_init);