@@ -202,6 +202,21 @@ static void *etm_setup_aux(int event_cpu, void **pages,
if (!event_data)
return NULL;
+ /*
+ * 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)
+ return NULL;
+
INIT_WORK(&event_data->work, free_event_data);
mask = &event_data->mask;
@@ -219,25 +234,11 @@ static void *etm_setup_aux(int event_cpu, void **pages,
* 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);
+ event_data->path[cpu] = coresight_build_path(csdev, sink);
if (IS_ERR(event_data->path[cpu]))
goto err;
}
- /*
- * 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 and a way to convey
- * sink assignement from the perf cmd line we need to assume tracers
- * in a trace session are using the same sink. Therefore pick the sink
- * found at the end of the first available path.
- */
- cpu = cpumask_first(mask);
- /* Grab the sink at the end of the path */
- sink = coresight_get_sink(event_data->path[cpu]);
- if (!sink)
- goto err;
-
if (!sink_ops(sink)->alloc_buffer)
goto err;
@@ -111,7 +111,9 @@ static inline void CS_UNLOCK(void __iomem *addr)
void coresight_disable_path(struct list_head *path);
int coresight_enable_path(struct list_head *path, u32 mode);
struct coresight_device *coresight_get_sink(struct list_head *path);
-struct list_head *coresight_build_path(struct coresight_device *csdev);
+struct coresight_device *coresight_get_enabled_sink(bool reset);
+struct list_head *coresight_build_path(struct coresight_device *csdev,
+ struct coresight_device *sink);
void coresight_release_path(struct list_head *path);
#ifdef CONFIG_CORESIGHT_SOURCE_ETM3X
@@ -368,6 +368,52 @@ struct coresight_device *coresight_get_sink(struct list_head *path)
return csdev;
}
+static int coresight_enabled_sink(struct device *dev, void *data)
+{
+ bool *reset = data;
+ struct coresight_device *csdev = to_coresight_device(dev);
+
+ if ((csdev->type == CORESIGHT_DEV_TYPE_SINK ||
+ csdev->type == CORESIGHT_DEV_TYPE_LINKSINK) &&
+ csdev->activated) {
+ /*
+ * Now that we have a handle on the sink for this session,
+ * disable the sysFS "enable_sink" flag so that possible
+ * concurrent perf session that wish to use another sink don't
+ * trip on it. Doing so has no ramification for the current
+ * session.
+ */
+ if (*reset)
+ csdev->activated = false;
+
+ return 1;
+ }
+
+ return 0;
+}
+
+/**
+ * coresight_get_enabled_sink - returns the first enabled sink found on the bus
+ * @deactivate: Whether the 'enable_sink' flag should be reset
+ *
+ * When operated from perf the deactivate parameter should be set to 'true'.
+ * That way the "enabled_sink" flag of the sink that was selected can be reset,
+ * allowing for other concurrent perf sessions to choose a different sink.
+ *
+ * When operated from sysFS users have full control and as such the deactivate
+ * parameter should be set to 'false', hence mandating users to explicitly
+ * clear the flag.
+ */
+struct coresight_device *coresight_get_enabled_sink(bool deactivate)
+{
+ struct device *dev = NULL;
+
+ dev = bus_find_device(&coresight_bustype, NULL, &deactivate,
+ coresight_enabled_sink);
+
+ return dev ? to_coresight_device(dev) : NULL;
+}
+
/**
* _coresight_build_path - recursively build a path from a @csdev to a sink.
* @csdev: The device to start from.
@@ -380,6 +426,7 @@ struct coresight_device *coresight_get_sink(struct list_head *path)
* last one.
*/
static int _coresight_build_path(struct coresight_device *csdev,
+ struct coresight_device *sink,
struct list_head *path)
{
int i;
@@ -387,15 +434,15 @@ static int _coresight_build_path(struct coresight_device *csdev,
struct coresight_node *node;
/* An activated sink has been found. Enqueue the element */
- if ((csdev->type == CORESIGHT_DEV_TYPE_SINK ||
- csdev->type == CORESIGHT_DEV_TYPE_LINKSINK) && csdev->activated)
+ if (csdev == sink)
goto out;
/* Not a sink - recursively explore each port found on this element */
for (i = 0; i < csdev->nr_outport; i++) {
struct coresight_device *child_dev = csdev->conns[i].child_dev;
- if (child_dev && _coresight_build_path(child_dev, path) == 0) {
+ if (child_dev &&
+ _coresight_build_path(child_dev, sink, path) == 0) {
found = true;
break;
}
@@ -422,18 +469,22 @@ static int _coresight_build_path(struct coresight_device *csdev,
return 0;
}
-struct list_head *coresight_build_path(struct coresight_device *csdev)
+struct list_head *coresight_build_path(struct coresight_device *source,
+ struct coresight_device *sink)
{
struct list_head *path;
int rc;
+ if (!sink)
+ return ERR_PTR(-EINVAL);
+
path = kzalloc(sizeof(struct list_head), GFP_KERNEL);
if (!path)
return ERR_PTR(-ENOMEM);
INIT_LIST_HEAD(path);
- rc = _coresight_build_path(csdev, path);
+ rc = _coresight_build_path(source, sink, path);
if (rc) {
kfree(path);
return ERR_PTR(rc);
@@ -497,6 +548,7 @@ static int coresight_validate_source(struct coresight_device *csdev,
int coresight_enable(struct coresight_device *csdev)
{
int cpu, ret = 0;
+ struct coresight_device *sink;
struct list_head *path;
mutex_lock(&coresight_mutex);
@@ -508,7 +560,17 @@ int coresight_enable(struct coresight_device *csdev)
if (csdev->enable)
goto out;
- path = coresight_build_path(csdev);
+ /*
+ * Search for a valid sink for this session but don't reset the
+ * "enable_sink" flag in sysFS. Users get to do that explicitly.
+ */
+ sink = coresight_get_enabled_sink(false);
+ if (!sink) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ path = coresight_build_path(csdev, sink);
if (IS_ERR(path)) {
pr_err("building path(s) failed\n");
ret = PTR_ERR(path);