drivers/hwtracing/coresight/coresight-etm-perf.c - kernel/common - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright(C) 2015 Linaro Limited. All rights reserved.
  * Author: Mathieu Poirier <[email protected]>
  */

 #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/percpu-defs.h>
 #include <linux/slab.h>
 #include <linux/stringhash.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;

 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(contextid,	"config:" __stringify(ETM_OPT_CTXTID));
 PMU_FORMAT_ATTR(timestamp,	"config:" __stringify(ETM_OPT_TS));
 PMU_FORMAT_ATTR(retstack,	"config:" __stringify(ETM_OPT_RETSTK));
 /* Sink ID - same for all ETMs */
 PMU_FORMAT_ATTR(sinkid,		"config2:0-31");

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

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

 static struct attribute *etm_config_sinks_attr[] = {
 	NULL,
 };

 static const struct attribute_group etm_pmu_sinks_group = {
 	.name   = "sinks",
 	.attrs  = etm_config_sinks_attr,
 };

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

 static inline struct list_head **
 etm_event_cpu_path_ptr(struct etm_event_data *data, int cpu)
 {
 	return per_cpu_ptr(data->path, cpu);
 }

 static inline struct list_head *
 etm_event_cpu_path(struct etm_event_data *data, int cpu)
 {
 	return *etm_event_cpu_path_ptr(data, cpu);
 }

 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_sink_buffer(struct etm_event_data *event_data)
 {
 	int cpu;
 	cpumask_t *mask = &event_data->mask;
 	struct coresight_device *sink;

 	if (WARN_ON(cpumask_empty(mask)))
 		return;

 	if (!event_data->snk_config)
 		return;

 	cpu = cpumask_first(mask);
 	sink = coresight_get_sink(etm_event_cpu_path(event_data, cpu));
 	sink_ops(sink)->free_buffer(event_data->snk_config);
 }

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

 	event_data = container_of(work, struct etm_event_data, work);
 	mask = &event_data->mask;

 	/* Free the sink buffers, if there are any */
 	free_sink_buffer(event_data);

 	for_each_cpu(cpu, mask) {
 		struct list_head **ppath;

 		ppath = etm_event_cpu_path_ptr(event_data, cpu);
 		if (!(IS_ERR_OR_NULL(*ppath)))
 			coresight_release_path(*ppath);
 		*ppath = NULL;
 	}

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

 static void *alloc_event_data(int cpu)
 {
 	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;


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

 	/*
 	 * 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 = alloc_percpu(struct list_head *);

 	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(struct perf_event *event, void **pages,
 			   int nr_pages, bool overwrite)
 {
 	u32 id;
 	int cpu = event->cpu;
 	cpumask_t *mask;
 	struct coresight_device *sink;
 	struct etm_event_data *event_data = NULL;

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

 	/* First get the selected sink from user space. */
 	if (event->attr.config2) {
 		id = (u32)event->attr.config2;
 		sink = coresight_get_sink_by_id(id);
 	} else {
 		sink = coresight_get_enabled_sink(true);
 	}

 	if (!sink)
 		goto err;

 	mask = &event_data->mask;

 	/*
 	 * Setup the path for each CPU in a trace session. We try to build
 	 * trace path for each CPU in the mask. If we don't find an ETM
 	 * for the CPU or fail to build a path, we clear the CPU from the
 	 * mask and continue with the rest. If ever we try to trace on those
 	 * CPUs, we can handle it and fail the session.
 	 */
 	for_each_cpu(cpu, mask) {
 		struct list_head *path;
 		struct coresight_device *csdev;

 		csdev = per_cpu(csdev_src, cpu);
 		/*
 		 * If there is no ETM associated with this CPU clear it from
 		 * the mask and continue with the rest. If ever we try to trace
 		 * on this CPU, we handle it accordingly.
 		 */
 		if (!csdev) {
 			cpumask_clear_cpu(cpu, mask);
 			continue;
 		}

 		/*
 		 * 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.
 		 */
 		path = coresight_build_path(csdev, sink);
 		if (IS_ERR(path)) {
 			cpumask_clear_cpu(cpu, mask);
 			continue;
 		}

 		*etm_event_cpu_path_ptr(event_data, cpu) = path;
 	}

 	/* If we don't have any CPUs ready for tracing, abort */
 	cpu = cpumask_first(mask);
 	if (cpu >= nr_cpu_ids)
 		goto err;

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

 	/* Allocate the sink buffer for this session */
 	event_data->snk_config =
 			sink_ops(sink)->alloc_buffer(sink, event, 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);
 	struct list_head *path;

 	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;

 	path = etm_event_cpu_path(event_data, cpu);
 	/* We need a sink, no need to continue without one */
 	sink = coresight_get_sink(path);
 	if (WARN_ON_ONCE(!sink))
 		goto fail_end_stop;

 	/* Nothing will happen without a path */
 	if (coresight_enable_path(path, CS_MODE_PERF, handle))
 		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_disable_path;

 out:
 	return;

 fail_disable_path:
 	coresight_disable_path(path);
 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);
 	struct list_head *path;

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

 	if (!csdev)
 		return;

 	path = etm_event_cpu_path(event_data, cpu);
 	if (!path)
 		return;

 	sink = coresight_get_sink(path);
 	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;

 		size = sink_ops(sink)->update_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(path);
 }

 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;

 		/* filter::size==0 means single address trigger */
 		if (filter->size) {
 			/*
 			 * The existing code relies on START/STOP filters
 			 * being address filters.
 			 */
 			if (filter->action == PERF_ADDR_FILTER_ACTION_START ||
 			    filter->action == PERF_ADDR_FILTER_ACTION_STOP)
 				return -EOPNOTSUPP;

 			range = true;
 		} else
 			address = true;

 		/*
 		 * At this time we don't allow range and start/stop filtering
 		 * to cohabitate, they have to be mutually exclusive.
 		 */
 		if (range && address)
 			return -EOPNOTSUPP;
 	}

 	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;
 	struct perf_addr_filter_range *fr = event->addr_filter_ranges;
 	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 = fr[i].start;
 		stop = start + fr[i].size;
 		etm_filter = &filters->etm_filter[i];

 		switch (filter->action) {
 		case PERF_ADDR_FILTER_ACTION_FILTER:
 			etm_filter->start_addr = start;
 			etm_filter->stop_addr = stop;
 			etm_filter->type = ETM_ADDR_TYPE_RANGE;
 			break;
 		case PERF_ADDR_FILTER_ACTION_START:
 			etm_filter->start_addr = start;
 			etm_filter->type = ETM_ADDR_TYPE_START;
 			break;
 		case PERF_ADDR_FILTER_ACTION_STOP:
 			etm_filter->stop_addr = stop;
 			etm_filter->type = ETM_ADDR_TYPE_STOP;
 			break;
 		}
 		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 ssize_t etm_perf_sink_name_show(struct device *dev,
 				       struct device_attribute *dattr,
 				       char *buf)
 {
 	struct dev_ext_attribute *ea;

 	ea = container_of(dattr, struct dev_ext_attribute, attr);
 	return scnprintf(buf, PAGE_SIZE, "0x%lx\n", (unsigned long)(ea->var));
 }

 int etm_perf_add_symlink_sink(struct coresight_device *csdev)
 {
 	int ret;
 	unsigned long hash;
 	const char *name;
 	struct device *pmu_dev = etm_pmu.dev;
 	struct device *dev = &csdev->dev;
 	struct dev_ext_attribute *ea;

 	if (csdev->type != CORESIGHT_DEV_TYPE_SINK &&
 	    csdev->type != CORESIGHT_DEV_TYPE_LINKSINK)
 		return -EINVAL;

 	if (csdev->ea != NULL)
 		return -EINVAL;

 	if (!etm_perf_up)
 		return -EPROBE_DEFER;

 	ea = devm_kzalloc(dev, sizeof(*ea), GFP_KERNEL);
 	if (!ea)
 		return -ENOMEM;

 	name = dev_name(dev);
 	/* See function coresight_get_sink_by_id() to know where this is used */
 	hash = hashlen_hash(hashlen_string(NULL, name));

 	sysfs_attr_init(&ea->attr.attr);
 	ea->attr.attr.name = devm_kstrdup(dev, name, GFP_KERNEL);
 	if (!ea->attr.attr.name)
 		return -ENOMEM;

 	ea->attr.attr.mode = 0444;
 	ea->attr.show = etm_perf_sink_name_show;
 	ea->var = (unsigned long *)hash;

 	ret = sysfs_add_file_to_group(&pmu_dev->kobj,
 				      &ea->attr.attr, "sinks");

 	if (!ret)
 		csdev->ea = ea;

 	return ret;
 }

 void etm_perf_del_symlink_sink(struct coresight_device *csdev)
 {
 	struct device *pmu_dev = etm_pmu.dev;
 	struct dev_ext_attribute *ea = csdev->ea;

 	if (csdev->type != CORESIGHT_DEV_TYPE_SINK &&
 	    csdev->type != CORESIGHT_DEV_TYPE_LINKSINK)
 		return;

 	if (!ea)
 		return;

 	sysfs_remove_file_from_group(&pmu_dev->kobj,
 				     &ea->attr.attr, "sinks");
 	csdev->ea = NULL;
 }

 static int __init etm_perf_init(void)
 {
 	int ret;

 	etm_pmu.capabilities		= (PERF_PMU_CAP_EXCLUSIVE |
 					   PERF_PMU_CAP_ITRACE);

 	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);
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Copyright(C) 2015 Linaro Limited. All rights reserved.
	* Author: Mathieu Poirier <[email protected]>
	*/

	#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/percpu-defs.h>
	#include <linux/slab.h>
	#include <linux/stringhash.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;

	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(contextid, "config:" __stringify(ETM_OPT_CTXTID));
	PMU_FORMAT_ATTR(timestamp, "config:" __stringify(ETM_OPT_TS));
	PMU_FORMAT_ATTR(retstack, "config:" __stringify(ETM_OPT_RETSTK));
	/* Sink ID - same for all ETMs */
	PMU_FORMAT_ATTR(sinkid, "config2:0-31");

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

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

	static struct attribute *etm_config_sinks_attr[] = {
	NULL,
	};

	static const struct attribute_group etm_pmu_sinks_group = {
	.name = "sinks",
	.attrs = etm_config_sinks_attr,
	};

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

	static inline struct list_head **
	etm_event_cpu_path_ptr(struct etm_event_data *data, int cpu)
	{
	return per_cpu_ptr(data->path, cpu);
	}

	static inline struct list_head *
	etm_event_cpu_path(struct etm_event_data *data, int cpu)
	{
	return *etm_event_cpu_path_ptr(data, cpu);
	}

	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_sink_buffer(struct etm_event_data *event_data)
	{
	int cpu;
	cpumask_t *mask = &event_data->mask;
	struct coresight_device *sink;

	if (WARN_ON(cpumask_empty(mask)))
	return;

	if (!event_data->snk_config)
	return;

	cpu = cpumask_first(mask);
	sink = coresight_get_sink(etm_event_cpu_path(event_data, cpu));
	sink_ops(sink)->free_buffer(event_data->snk_config);
	}

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

	event_data = container_of(work, struct etm_event_data, work);
	mask = &event_data->mask;

	/* Free the sink buffers, if there are any */
	free_sink_buffer(event_data);

	for_each_cpu(cpu, mask) {
	struct list_head **ppath;

	ppath = etm_event_cpu_path_ptr(event_data, cpu);
	if (!(IS_ERR_OR_NULL(*ppath)))
	coresight_release_path(*ppath);
	*ppath = NULL;
	}

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

	static void *alloc_event_data(int cpu)
	{
	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;


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

	/*
	* 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 = alloc_percpu(struct list_head *);

	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(struct perf_event event, void **pages,
	int nr_pages, bool overwrite)
	{
	u32 id;
	int cpu = event->cpu;
	cpumask_t *mask;
	struct coresight_device *sink;
	struct etm_event_data *event_data = NULL;

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

	/* First get the selected sink from user space. */
	if (event->attr.config2) {
	id = (u32)event->attr.config2;
	sink = coresight_get_sink_by_id(id);
	} else {
	sink = coresight_get_enabled_sink(true);
	}

	if (!sink)
	goto err;

	mask = &event_data->mask;

	/*
	* Setup the path for each CPU in a trace session. We try to build
	* trace path for each CPU in the mask. If we don't find an ETM
	* for the CPU or fail to build a path, we clear the CPU from the
	* mask and continue with the rest. If ever we try to trace on those
	* CPUs, we can handle it and fail the session.
	*/
	for_each_cpu(cpu, mask) {
	struct list_head *path;
	struct coresight_device *csdev;

	csdev = per_cpu(csdev_src, cpu);
	/*
	* If there is no ETM associated with this CPU clear it from
	* the mask and continue with the rest. If ever we try to trace
	* on this CPU, we handle it accordingly.
	*/
	if (!csdev) {
	cpumask_clear_cpu(cpu, mask);
	continue;
	}

	/*
	* 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.
	*/
	path = coresight_build_path(csdev, sink);
	if (IS_ERR(path)) {
	cpumask_clear_cpu(cpu, mask);
	continue;
	}

	*etm_event_cpu_path_ptr(event_data, cpu) = path;
	}

	/* If we don't have any CPUs ready for tracing, abort */
	cpu = cpumask_first(mask);
	if (cpu >= nr_cpu_ids)
	goto err;

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

	/* Allocate the sink buffer for this session */
	event_data->snk_config =
	sink_ops(sink)->alloc_buffer(sink, event, 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);
	struct list_head *path;

	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;

	path = etm_event_cpu_path(event_data, cpu);
	/* We need a sink, no need to continue without one */
	sink = coresight_get_sink(path);
	if (WARN_ON_ONCE(!sink))
	goto fail_end_stop;

	/* Nothing will happen without a path */
	if (coresight_enable_path(path, CS_MODE_PERF, handle))
	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_disable_path;

	out:
	return;

	fail_disable_path:
	coresight_disable_path(path);
	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);
	struct list_head *path;

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

	if (!csdev)
	return;

	path = etm_event_cpu_path(event_data, cpu);
	if (!path)
	return;

	sink = coresight_get_sink(path);
	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;

	size = sink_ops(sink)->update_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(path);
	}

	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;

	/* filter::size==0 means single address trigger */
	if (filter->size) {
	/*
	* The existing code relies on START/STOP filters
	* being address filters.
	*/
	if (filter->action == PERF_ADDR_FILTER_ACTION_START \|\|
	filter->action == PERF_ADDR_FILTER_ACTION_STOP)
	return -EOPNOTSUPP;

	range = true;
	} else
	address = true;

	/*
	* At this time we don't allow range and start/stop filtering
	* to cohabitate, they have to be mutually exclusive.
	*/
	if (range && address)
	return -EOPNOTSUPP;
	}

	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;
	struct perf_addr_filter_range *fr = event->addr_filter_ranges;
	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 = fr[i].start;
	stop = start + fr[i].size;
	etm_filter = &filters->etm_filter[i];

	switch (filter->action) {
	case PERF_ADDR_FILTER_ACTION_FILTER:
	etm_filter->start_addr = start;
	etm_filter->stop_addr = stop;
	etm_filter->type = ETM_ADDR_TYPE_RANGE;
	break;
	case PERF_ADDR_FILTER_ACTION_START:
	etm_filter->start_addr = start;
	etm_filter->type = ETM_ADDR_TYPE_START;
	break;
	case PERF_ADDR_FILTER_ACTION_STOP:
	etm_filter->stop_addr = stop;
	etm_filter->type = ETM_ADDR_TYPE_STOP;
	break;
	}
	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 ssize_t etm_perf_sink_name_show(struct device *dev,
	struct device_attribute *dattr,
	char *buf)
	{
	struct dev_ext_attribute *ea;

	ea = container_of(dattr, struct dev_ext_attribute, attr);
	return scnprintf(buf, PAGE_SIZE, "0x%lx\n", (unsigned long)(ea->var));
	}

	int etm_perf_add_symlink_sink(struct coresight_device *csdev)
	{
	int ret;
	unsigned long hash;
	const char *name;
	struct device *pmu_dev = etm_pmu.dev;
	struct device *dev = &csdev->dev;
	struct dev_ext_attribute *ea;

	if (csdev->type != CORESIGHT_DEV_TYPE_SINK &&
	csdev->type != CORESIGHT_DEV_TYPE_LINKSINK)
	return -EINVAL;

	if (csdev->ea != NULL)
	return -EINVAL;

	if (!etm_perf_up)
	return -EPROBE_DEFER;

	ea = devm_kzalloc(dev, sizeof(*ea), GFP_KERNEL);
	if (!ea)
	return -ENOMEM;

	name = dev_name(dev);
	/* See function coresight_get_sink_by_id() to know where this is used */
	hash = hashlen_hash(hashlen_string(NULL, name));

	sysfs_attr_init(&ea->attr.attr);
	ea->attr.attr.name = devm_kstrdup(dev, name, GFP_KERNEL);
	if (!ea->attr.attr.name)
	return -ENOMEM;

	ea->attr.attr.mode = 0444;
	ea->attr.show = etm_perf_sink_name_show;
	ea->var = (unsigned long *)hash;

	ret = sysfs_add_file_to_group(&pmu_dev->kobj,
	&ea->attr.attr, "sinks");

	if (!ret)
	csdev->ea = ea;

	return ret;
	}

	void etm_perf_del_symlink_sink(struct coresight_device *csdev)
	{
	struct device *pmu_dev = etm_pmu.dev;
	struct dev_ext_attribute *ea = csdev->ea;

	if (csdev->type != CORESIGHT_DEV_TYPE_SINK &&
	csdev->type != CORESIGHT_DEV_TYPE_LINKSINK)
	return;

	if (!ea)
	return;

	sysfs_remove_file_from_group(&pmu_dev->kobj,
	&ea->attr.attr, "sinks");
	csdev->ea = NULL;
	}

	static int __init etm_perf_init(void)
	{
	int ret;

	etm_pmu.capabilities = (PERF_PMU_CAP_EXCLUSIVE \|
	PERF_PMU_CAP_ITRACE);

	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);