[PATCH 0/6] coresight: next v5.0-rc5

[PATCH 0/6] coresight: next v5.0-rc5

[Mathieu Poirier]

Hi Greg,

Here is what I collected for inclusion in the 5.1 cycle, please have a look when
you have a minute.

Applies cleanly on the char-misc-next branch (9f23379c67fa).

Thanks,
Mathieu

Leo Yan (1):
  coresight: cpu-debug: Support for CA73 CPUs

Mathieu Poirier (3):
  perf/aux: Make perf_event accessible to setup_aux()
  coresight: perf: Add "sinks" group to PMU directory
  coresight: Use event attributes for sink selection

Rob Herring (1):
  coresight: Use of_node_name_eq for node name comparisons

YueHaibing (1):
  coresight: stm: Remove set but not used variable 'res_size'

 arch/s390/kernel/perf_cpum_sf.c               |   6 +-
 arch/x86/events/intel/bts.c                   |   4 +-
 arch/x86/events/intel/pt.c                    |   5 +-
 .../hwtracing/coresight/coresight-cpu-debug.c |   4 +
 .../hwtracing/coresight/coresight-etm-perf.c  | 112 +++++++++++++++---
 .../hwtracing/coresight/coresight-etm-perf.h  |   6 +-
 drivers/hwtracing/coresight/coresight-priv.h  |   1 +
 drivers/hwtracing/coresight/coresight-stm.c   |  12 +-
 drivers/hwtracing/coresight/coresight.c       |  60 ++++++++++
 drivers/hwtracing/coresight/of_coresight.c    |   4 +-
 drivers/perf/arm_spe_pmu.c                    |   6 +-
 include/linux/coresight.h                     |   7 +-
 include/linux/perf_event.h                    |   2 +-
 kernel/events/ring_buffer.c                   |   2 +-
 14 files changed, 192 insertions(+), 39 deletions(-)

-- 
2.17.1

[PATCH 1/6] coresight: cpu-debug: Support for CA73 CPUs

[Mathieu Poirier]

From: Leo Yan <leo.yan@linaro.org>

This patch is to add the AMBA device ID for CA73 CPU, so that CPU debug
module can be initialized successfully when a SoC contain CA73 CPUs.

This patch has been verified on 96boards Hikey960.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
 drivers/hwtracing/coresight/coresight-cpu-debug.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-cpu-debug.c b/drivers/hwtracing/coresight/coresight-cpu-debug.c
index 45b2460f3166..e8819d750938 100644
--- a/drivers/hwtracing/coresight/coresight-cpu-debug.c
+++ b/drivers/hwtracing/coresight/coresight-cpu-debug.c
@@ -668,6 +668,10 @@ static const struct amba_id debug_ids[] = {
 		.id	= 0x000bbd08,
 		.mask	= 0x000fffff,
 	},
+	{       /* Debug for Cortex-A73 */
+		.id	= 0x000bbd09,
+		.mask	= 0x000fffff,
+	},
 	{ 0, 0 },
 };
 
-- 
2.17.1

[PATCH 2/6] coresight: stm: Remove set but not used variable 'res_size'

[Mathieu Poirier]

From: YueHaibing <yuehaibing@huawei.com>

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/hwtracing/coresight/coresight-stm.c: In function 'stm_probe':
drivers/hwtracing/coresight/coresight-stm.c:796:9: warning:
 variable 'res_size' set but not used [-Wunused-but-set-variable]

It never used since introduction in commit 237483aa5cf4 ("coresight: stm:
adding driver for CoreSight STM component")

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Tested-by: Leo Yan <leo.yan@linaro.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
 drivers/hwtracing/coresight/coresight-stm.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-stm.c b/drivers/hwtracing/coresight/coresight-stm.c
index ef339ff22090..f07825df5c7a 100644
--- a/drivers/hwtracing/coresight/coresight-stm.c
+++ b/drivers/hwtracing/coresight/coresight-stm.c
@@ -793,7 +793,7 @@ static int stm_probe(struct amba_device *adev, const struct amba_id *id)
 	struct stm_drvdata *drvdata;
 	struct resource *res = &adev->res;
 	struct resource ch_res;
-	size_t res_size, bitmap_size;
+	size_t bitmap_size;
 	struct coresight_desc desc = { 0 };
 	struct device_node *np = adev->dev.of_node;
 
@@ -833,15 +833,11 @@ static int stm_probe(struct amba_device *adev, const struct amba_id *id)
 
 	drvdata->write_bytes = stm_fundamental_data_size(drvdata);
 
-	if (boot_nr_channel) {
+	if (boot_nr_channel)
 		drvdata->numsp = boot_nr_channel;
-		res_size = min((resource_size_t)(boot_nr_channel *
-				  BYTES_PER_CHANNEL), resource_size(res));
-	} else {
+	else
 		drvdata->numsp = stm_num_stimulus_port(drvdata);
-		res_size = min((resource_size_t)(drvdata->numsp *
-				 BYTES_PER_CHANNEL), resource_size(res));
-	}
+
 	bitmap_size = BITS_TO_LONGS(drvdata->numsp) * sizeof(long);
 
 	guaranteed = devm_kzalloc(dev, bitmap_size, GFP_KERNEL);
-- 
2.17.1

[PATCH 3/6] coresight: Use of_node_name_eq for node name comparisons

[Mathieu Poirier]

From: Rob Herring <robh@kernel.org>

Convert string compares of DT node names to use of_node_name_eq helper
instead. This removes direct access to the node name pointer.

Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
 drivers/hwtracing/coresight/of_coresight.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/hwtracing/coresight/of_coresight.c b/drivers/hwtracing/coresight/of_coresight.c
index 89092f83567e..7045930fc958 100644
--- a/drivers/hwtracing/coresight/of_coresight.c
+++ b/drivers/hwtracing/coresight/of_coresight.c
@@ -80,8 +80,8 @@ static struct device_node *of_coresight_get_port_parent(struct device_node *ep)
 	 * Skip one-level up to the real device node, if we
 	 * are using the new bindings.
 	 */
-	if (!of_node_cmp(parent->name, "in-ports") ||
-	    !of_node_cmp(parent->name, "out-ports"))
+	if (of_node_name_eq(parent, "in-ports") ||
+	    of_node_name_eq(parent, "out-ports"))
 		parent = of_get_next_parent(parent);
 
 	return parent;
-- 
2.17.1

[PATCH 4/6] perf/aux: Make perf_event accessible to setup_aux()

[Mathieu Poirier]

When pmu::setup_aux() is called the coresight PMU needs to know which
sink to use for the session by looking up the information in the
event's attr::config2 field.

As such simply replace the cpu information by the complete perf_event
structure and change all affected customers.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 arch/s390/kernel/perf_cpum_sf.c                  | 6 +++---
 arch/x86/events/intel/bts.c                      | 4 +++-
 arch/x86/events/intel/pt.c                       | 5 +++--
 drivers/hwtracing/coresight/coresight-etm-perf.c | 6 +++---
 drivers/perf/arm_spe_pmu.c                       | 6 +++---
 include/linux/perf_event.h                       | 2 +-
 kernel/events/ring_buffer.c                      | 2 +-
 7 files changed, 17 insertions(+), 14 deletions(-)

diff --git a/arch/s390/kernel/perf_cpum_sf.c b/arch/s390/kernel/perf_cpum_sf.c
index bfabeb1889cc..1266194afb02 100644
--- a/arch/s390/kernel/perf_cpum_sf.c
+++ b/arch/s390/kernel/perf_cpum_sf.c
@@ -1600,7 +1600,7 @@ static void aux_sdb_init(unsigned long sdb)
 
 /*
  * aux_buffer_setup() - Setup AUX buffer for diagnostic mode sampling
- * @cpu:	On which to allocate, -1 means current
+ * @event:	Event the buffer is setup for, event->cpu == -1 means current
  * @pages:	Array of pointers to buffer pages passed from perf core
  * @nr_pages:	Total pages
  * @snapshot:	Flag for snapshot mode
@@ -1612,8 +1612,8 @@ static void aux_sdb_init(unsigned long sdb)
  *
  * Return the private AUX buffer structure if success or NULL if fails.
  */
-static void *aux_buffer_setup(int cpu, void **pages, int nr_pages,
-			      bool snapshot)
+static void *aux_buffer_setup(struct perf_event *event, void **pages,
+			      int nr_pages, bool snapshot)
 {
 	struct sf_buffer *sfb;
 	struct aux_buffer *aux;
diff --git a/arch/x86/events/intel/bts.c b/arch/x86/events/intel/bts.c
index a01ef1b0f883..7cdd7b13bbda 100644
--- a/arch/x86/events/intel/bts.c
+++ b/arch/x86/events/intel/bts.c
@@ -77,10 +77,12 @@ static size_t buf_size(struct page *page)
 }
 
 static void *
-bts_buffer_setup_aux(int cpu, void **pages, int nr_pages, bool overwrite)
+bts_buffer_setup_aux(struct perf_event *event, void **pages,
+		     int nr_pages, bool overwrite)
 {
 	struct bts_buffer *buf;
 	struct page *page;
+	int cpu = event->cpu;
 	int node = (cpu == -1) ? cpu : cpu_to_node(cpu);
 	unsigned long offset;
 	size_t size = nr_pages << PAGE_SHIFT;
diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c
index 9494ca68fd9d..c0e86ff21f81 100644
--- a/arch/x86/events/intel/pt.c
+++ b/arch/x86/events/intel/pt.c
@@ -1114,10 +1114,11 @@ static int pt_buffer_init_topa(struct pt_buffer *buf, unsigned long nr_pages,
  * Return:	Our private PT buffer structure.
  */
 static void *
-pt_buffer_setup_aux(int cpu, void **pages, int nr_pages, bool snapshot)
+pt_buffer_setup_aux(struct perf_event *event, void **pages,
+		    int nr_pages, bool snapshot)
 {
 	struct pt_buffer *buf;
-	int node, ret;
+	int node, ret, cpu = event->cpu;
 
 	if (!nr_pages)
 		return NULL;
diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c
index abe8249b893b..f21eb28b6782 100644
--- a/drivers/hwtracing/coresight/coresight-etm-perf.c
+++ b/drivers/hwtracing/coresight/coresight-etm-perf.c
@@ -177,15 +177,15 @@ static void etm_free_aux(void *data)
 	schedule_work(&event_data->work);
 }
 
-static void *etm_setup_aux(int event_cpu, void **pages,
+static void *etm_setup_aux(struct perf_event *event, void **pages,
 			   int nr_pages, bool overwrite)
 {
-	int cpu;
+	int cpu = event->cpu;
 	cpumask_t *mask;
 	struct coresight_device *sink;
 	struct etm_event_data *event_data = NULL;
 
-	event_data = alloc_event_data(event_cpu);
+	event_data = alloc_event_data(cpu);
 	if (!event_data)
 		return NULL;
 	INIT_WORK(&event_data->work, free_event_data);
diff --git a/drivers/perf/arm_spe_pmu.c b/drivers/perf/arm_spe_pmu.c
index 8e46a9dad2fa..7cb766dafe85 100644
--- a/drivers/perf/arm_spe_pmu.c
+++ b/drivers/perf/arm_spe_pmu.c
@@ -824,10 +824,10 @@ static void arm_spe_pmu_read(struct perf_event *event)
 {
 }
 
-static void *arm_spe_pmu_setup_aux(int cpu, void **pages, int nr_pages,
-				   bool snapshot)
+static void *arm_spe_pmu_setup_aux(struct perf_event *event, void **pages,
+				   int nr_pages, bool snapshot)
 {
-	int i;
+	int i, cpu = event->cpu;
 	struct page **pglist;
 	struct arm_spe_pmu_buf *buf;
 
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 1d5c551a5add..3e49b2144808 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -409,7 +409,7 @@ struct pmu {
 	/*
 	 * Set up pmu-private data structures for an AUX area
 	 */
-	void *(*setup_aux)		(int cpu, void **pages,
+	void *(*setup_aux)		(struct perf_event *event, void **pages,
 					 int nr_pages, bool overwrite);
 					/* optional */
 
diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c
index 4a9937076331..857308295f63 100644
--- a/kernel/events/ring_buffer.c
+++ b/kernel/events/ring_buffer.c
@@ -658,7 +658,7 @@ int rb_alloc_aux(struct ring_buffer *rb, struct perf_event *event,
 			goto out;
 	}
 
-	rb->aux_priv = event->pmu->setup_aux(event->cpu, rb->aux_pages, nr_pages,
+	rb->aux_priv = event->pmu->setup_aux(event, rb->aux_pages, nr_pages,
 					     overwrite);
 	if (!rb->aux_priv)
 		goto out;
-- 
2.17.1

[PATCH 5/6] coresight: perf: Add "sinks" group to PMU directory

[Mathieu Poirier]

Add a "sinks" directory entry so that users can see all the sinks
available in the system in a single place.  Individual sink are added
as they are registered with the coresight bus.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
---
 .../hwtracing/coresight/coresight-etm-perf.c  | 82 +++++++++++++++++++
 .../hwtracing/coresight/coresight-etm-perf.h  |  6 +-
 drivers/hwtracing/coresight/coresight.c       | 18 ++++
 include/linux/coresight.h                     |  7 +-
 4 files changed, 110 insertions(+), 3 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c
index f21eb28b6782..cdbdb28dc175 100644
--- a/drivers/hwtracing/coresight/coresight-etm-perf.c
+++ b/drivers/hwtracing/coresight/coresight-etm-perf.c
@@ -14,6 +14,7 @@
 #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>
 
@@ -43,8 +44,18 @@ static const struct attribute_group etm_pmu_format_group = {
 	.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,
 };
 
@@ -479,6 +490,77 @@ int etm_perf_symlink(struct coresight_device *csdev, bool link)
 	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 *pdev = csdev->dev.parent;
+	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(pdev, sizeof(*ea), GFP_KERNEL);
+	if (!ea)
+		return -ENOMEM;
+
+	name = dev_name(pdev);
+	/* See function coresight_get_sink_by_id() to know where this is used */
+	hash = hashlen_hash(hashlen_string(NULL, name));
+
+	ea->attr.attr.name = devm_kstrdup(pdev, 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;
diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.h b/drivers/hwtracing/coresight/coresight-etm-perf.h
index da7d9336a15c..015213abe00a 100644
--- a/drivers/hwtracing/coresight/coresight-etm-perf.h
+++ b/drivers/hwtracing/coresight/coresight-etm-perf.h
@@ -59,6 +59,8 @@ struct etm_event_data {
 
 #ifdef CONFIG_CORESIGHT
 int etm_perf_symlink(struct coresight_device *csdev, bool link);
+int etm_perf_add_symlink_sink(struct coresight_device *csdev);
+void etm_perf_del_symlink_sink(struct coresight_device *csdev);
 static inline void *etm_perf_sink_config(struct perf_output_handle *handle)
 {
 	struct etm_event_data *data = perf_get_aux(handle);
@@ -70,7 +72,9 @@ static inline void *etm_perf_sink_config(struct perf_output_handle *handle)
 #else
 static inline int etm_perf_symlink(struct coresight_device *csdev, bool link)
 { return -EINVAL; }
-
+int etm_perf_add_symlink_sink(struct coresight_device *csdev)
+{ return -EINVAL; }
+void etm_perf_del_symlink_sink(struct coresight_device *csdev) {}
 static inline void *etm_perf_sink_config(struct perf_output_handle *handle)
 {
 	return NULL;
diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c
index 2b0df1a0a8df..d7fa90be6f42 100644
--- a/drivers/hwtracing/coresight/coresight.c
+++ b/drivers/hwtracing/coresight/coresight.c
@@ -18,6 +18,7 @@
 #include <linux/delay.h>
 #include <linux/pm_runtime.h>
 
+#include "coresight-etm-perf.h"
 #include "coresight-priv.h"
 
 static DEFINE_MUTEX(coresight_mutex);
@@ -1167,6 +1168,22 @@ struct coresight_device *coresight_register(struct coresight_desc *desc)
 		goto err_out;
 	}
 
+	if (csdev->type == CORESIGHT_DEV_TYPE_SINK ||
+	    csdev->type == CORESIGHT_DEV_TYPE_LINKSINK) {
+		ret = etm_perf_add_symlink_sink(csdev);
+
+		if (ret) {
+			device_unregister(&csdev->dev);
+			/*
+			 * As with the above, all resources are free'd
+			 * explicitly via coresight_device_release() triggered
+			 * from put_device(), which is in turn called from
+			 * function device_unregister().
+			 */
+			goto err_out;
+		}
+	}
+
 	mutex_lock(&coresight_mutex);
 
 	coresight_fixup_device_conns(csdev);
@@ -1185,6 +1202,7 @@ EXPORT_SYMBOL_GPL(coresight_register);
 
 void coresight_unregister(struct coresight_device *csdev)
 {
+	etm_perf_del_symlink_sink(csdev);
 	/* Remove references of that device in the topology */
 	coresight_remove_conns(csdev);
 	device_unregister(&csdev->dev);
diff --git a/include/linux/coresight.h b/include/linux/coresight.h
index 46c67a764877..7b87965f7a65 100644
--- a/include/linux/coresight.h
+++ b/include/linux/coresight.h
@@ -154,8 +154,9 @@ struct coresight_connection {
  * @orphan:	true if the component has connections that haven't been linked.
  * @enable:	'true' if component is currently part of an active path.
  * @activated:	'true' only if a _sink_ has been activated.  A sink can be
-		activated but not yet enabled.  Enabling for a _sink_
-		happens when a source has been selected for that it.
+ *		activated but not yet enabled.  Enabling for a _sink_
+ *		appens when a source has been selected for that it.
+ * @ea:		Device attribute for sink representation under PMU directory.
  */
 struct coresight_device {
 	struct coresight_connection *conns;
@@ -168,7 +169,9 @@ struct coresight_device {
 	atomic_t *refcnt;
 	bool orphan;
 	bool enable;	/* true only if configured as part of a path */
+	/* sink specific fields */
 	bool activated;	/* true only if a sink is part of a path */
+	struct dev_ext_attribute *ea;
 };
 
 #define to_coresight_device(d) container_of(d, struct coresight_device, dev)
-- 
2.17.1

[PATCH 6/6] coresight: Use event attributes for sink selection

[Mathieu Poirier]

This patch uses the information conveyed by perf_event::attr::config2
to select a sink to use for the session.  That way a sink can easily be
selected to be used by more than one source, something that isn't currently
possible with the sysfs implementation.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
---
 .../hwtracing/coresight/coresight-etm-perf.c  | 24 +++++------
 drivers/hwtracing/coresight/coresight-priv.h  |  1 +
 drivers/hwtracing/coresight/coresight.c       | 42 +++++++++++++++++++
 3 files changed, 55 insertions(+), 12 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c
index cdbdb28dc175..8c88bf0a1e5f 100644
--- a/drivers/hwtracing/coresight/coresight-etm-perf.c
+++ b/drivers/hwtracing/coresight/coresight-etm-perf.c
@@ -31,11 +31,14 @@ static DEFINE_PER_CPU(struct coresight_device *, csdev_src);
 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));
+/* 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_timestamp.attr,
 	&format_attr_retstack.attr,
+	&format_attr_sinkid.attr,
 	NULL,
 };
 
@@ -191,6 +194,7 @@ static void etm_free_aux(void *data)
 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;
@@ -201,18 +205,14 @@ static void *etm_setup_aux(struct perf_event *event, void **pages,
 		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);
+	/* 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 || !sink_ops(sink)->alloc_buffer)
 		goto err;
 
diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h
index 579f34943bf1..b936c6d7e13f 100644
--- a/drivers/hwtracing/coresight/coresight-priv.h
+++ b/drivers/hwtracing/coresight/coresight-priv.h
@@ -147,6 +147,7 @@ void coresight_disable_path(struct list_head *path);
 int coresight_enable_path(struct list_head *path, u32 mode, void *sink_data);
 struct coresight_device *coresight_get_sink(struct list_head *path);
 struct coresight_device *coresight_get_enabled_sink(bool reset);
+struct coresight_device *coresight_get_sink_by_id(u32 id);
 struct list_head *coresight_build_path(struct coresight_device *csdev,
 				       struct coresight_device *sink);
 void coresight_release_path(struct list_head *path);
diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c
index d7fa90be6f42..29cef898afba 100644
--- a/drivers/hwtracing/coresight/coresight.c
+++ b/drivers/hwtracing/coresight/coresight.c
@@ -11,6 +11,7 @@
 #include <linux/err.h>
 #include <linux/export.h>
 #include <linux/slab.h>
+#include <linux/stringhash.h>
 #include <linux/mutex.h>
 #include <linux/clk.h>
 #include <linux/coresight.h>
@@ -541,6 +542,47 @@ struct coresight_device *coresight_get_enabled_sink(bool deactivate)
 	return dev ? to_coresight_device(dev) : NULL;
 }
 
+static int coresight_sink_by_id(struct device *dev, void *data)
+{
+	struct coresight_device *csdev = to_coresight_device(dev);
+	unsigned long hash;
+
+	if (csdev->type == CORESIGHT_DEV_TYPE_SINK ||
+	     csdev->type == CORESIGHT_DEV_TYPE_LINKSINK) {
+
+		if (!csdev->ea)
+			return 0;
+		/*
+		 * See function etm_perf_add_symlink_sink() to know where
+		 * this comes from.
+		 */
+		hash = (unsigned long)csdev->ea->var;
+
+		if ((u32)hash == *(u32 *)data)
+			return 1;
+	}
+
+	return 0;
+}
+
+/**
+ * coresight_get_sink_by_id - returns the sink that matches the id
+ * @id: Id of the sink to match
+ *
+ * The name of a sink is unique, whether it is found on the AMBA bus or
+ * otherwise.  As such the hash of that name can easily be used to identify
+ * a sink.
+ */
+struct coresight_device *coresight_get_sink_by_id(u32 id)
+{
+	struct device *dev = NULL;
+
+	dev = bus_find_device(&coresight_bustype, NULL, &id,
+			      coresight_sink_by_id);
+
+	return dev ? to_coresight_device(dev) : NULL;
+}
+
 /*
  * coresight_grab_device - Power up this device and any of the helper
  * devices connected to it for trace operation. Since the helper devices
-- 
2.17.1