[PATCH V3 6/6] coresight: etm-perf: incorporating sink definition from cmd line

Mathieu Poirier
2016-07-28T21:42:56Z

Now that PMU specific configuration is available as part of the event,
lookup the sink identified by users from the perf command line and build
a path from source to sink.

With this functionality it is no longer required to select a sink in a
separate step (from sysFS) before a perf trace session can be started.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
drivers/hwtracing/coresight/coresight-etm-perf.c | 101 ++++++++++++++++++++++-
1 file changed, 100 insertions(+), 1 deletion(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c
index f8c7a8733b23..5658a7411a66 100644
--- a/drivers/hwtracing/coresight/coresight-etm-perf.c
+++ b/drivers/hwtracing/coresight/coresight-etm-perf.c
@@ -22,6 +22,7 @@
#include <linux/list.h>
#include <linux/mm.h>
#include <linux/init.h>
+#include <linux/parser.h>
#include <linux/perf_event.h>
#include <linux/slab.h>
#include <linux/types.h>
@@ -71,11 +72,20 @@ static const struct attribute_group *etm_pmu_attr_groups[] = {

static void etm_event_read(struct perf_event *event) {}

+static void etm_event_destroy(struct perf_event *event)
+{
+ kfree(event->hw.drv_configs);
+ event->hw.drv_configs = NULL;
+}
+
static int etm_event_init(struct perf_event *event)
{
if (event->attr.type != etm_pmu.type)
return -ENOENT;

+ event->destroy = etm_event_destroy;
+ event->hw.drv_configs = NULL;
+
return 0;
}

@@ -159,6 +169,7 @@ static void *etm_setup_aux(struct perf_event *event, void **pages,
int nr_pages, bool overwrite)
{
int cpu;
+ char *cmdl_sink;
cpumask_t *mask;
struct coresight_device *sink;
struct etm_event_data *event_data = NULL;
@@ -171,6 +182,12 @@ static void *etm_setup_aux(struct perf_event *event, void **pages,

mask = &event_data->mask;

+ /*
+ * If a sink was specified from the perf cmdline it will be part of
+ * the event's drv_configs.
+ */
+ cmdl_sink = (char *)event->hw.drv_configs;
+
/* Setup the path for each CPU in a trace session */
for_each_cpu(cpu, mask) {
struct coresight_device *csdev;
@@ -184,7 +201,7 @@ static void *etm_setup_aux(struct perf_event *event, 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, NULL);
+ event_data->path[cpu] = coresight_build_path(csdev, cmdl_sink);
if (!event_data->path[cpu])
goto err;
}
@@ -342,6 +359,87 @@ static void etm_event_del(struct perf_event *event, int mode)
etm_event_stop(event, PERF_EF_UPDATE);
}

+enum {
+ ETM_TOKEN_SINK_CPU,
+ ETM_TOKEN_SINK,
+ ETM_TOKEN_ERR,
+};
+
+static const match_table_t drv_cfg_tokens = {
+ {ETM_TOKEN_SINK_CPU, "sink=cpu%d:%s"},
+ {ETM_TOKEN_SINK, "sink=%s"},
+ {ETM_TOKEN_ERR, NULL},
+};
+
+static int etm_set_drv_configs(struct perf_event *event, void __user *arg)
+{
+ char *config, *sink = NULL;
+ int cpu = -1, token, ret = 0;
+ substring_t args[MAX_OPT_ARGS];
+
+ /* Only one sink per event */
+ if (event->hw.drv_configs != NULL) {
+ ret = -EINVAL;
+ goto err;
+ }
+
+ /* Make user supplied input usable */
+ config = strndup_user(arg, PAGE_SIZE);
+ if (IS_ERR(config)) {
+ ret = PTR_ERR(config);
+ goto err;
+ }
+
+ /* See above declared @drv_cfg_tokens for the usable formats */
+ token = match_token(config, drv_cfg_tokens, args);
+ switch (token) {
+ case ETM_TOKEN_SINK:
+ /* Just a sink has been specified */
+ sink = match_strdup(&args[0]);
+ if (IS_ERR(sink)) {
+ ret = PTR_ERR(sink);
+ goto err;
+ }
+ break;
+ case ETM_TOKEN_SINK_CPU:
+ /* We have a sink and a CPU */
+
+ /* First get the cpu */
+ if (match_int(&args[0], &cpu)) {
+ ret = -EINVAL;
+ goto err;
+ }
+
+ /* Then the sink */
+ sink = match_strdup(&args[1]);
+ if (IS_ERR(sink)) {
+ ret = PTR_ERR(sink);
+ goto err;
+ }
+ break;
+ default:
+ ret = -EINVAL;
+ goto err;
+ }
+
+ /*
+ * If the CPUs don't match the sink is destined to another path. This
+ * isn't as an error hence not setting @ret.
+ */
+ if (event->cpu != cpu)
+ goto err;
+
+ /* We have a valid configuration */
+ event->hw.drv_configs = sink;
+
+out:
+ return ret;
+
+err:
+ kfree(sink);
+ goto out;
+}
+
int etm_perf_symlink(struct coresight_device *csdev, bool link)
{
char entry[sizeof("cpu9999999")];
@@ -383,6 +481,7 @@ static int __init etm_perf_init(void)
etm_pmu.stop = etm_event_stop;
etm_pmu.add = etm_event_add;
etm_pmu.del = etm_event_del;
+ etm_pmu.set_drv_configs = etm_set_drv_configs;

ret = perf_pmu_register(&etm_pmu, CORESIGHT_ETM_PMU_NAME, -1);
if (ret == 0)
--
2.7.4