coresight: Use event attributes for sink selection

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>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-s390@vger.kernel.org
Link: http://lkml.kernel.org/r/20190131184714.20388-4-mathieu.poirier@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c
index cdbdb28..8c88bf0 100644 (file)
--- 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 579f349..b936c6d 100644 (file)
--- 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 d7fa90b..29cef89 100644 (file)
--- 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