coresight: pmu: Adds return stack option to perf coresight pmu

Return stack is a programmable option on some ETM and PTM hardware.
Adds the option flags to enable this from the perf event command line.
Signed-off-by: NMike Leach <mike.leach@linaro.org>
Signed-off-by: NMathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hwtracing/coresight/coresight-etm-perf.c

@@ -53,10 +53,12 @@ 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(timestamp,	"config:" __stringify(ETM_OPT_TS));
+PMU_FORMAT_ATTR(retstack,	"config:" __stringify(ETM_OPT_RETSTK));
 
 static struct attribute *etm_config_formats_attr[] = {
 	&format_attr_cycacc.attr,
 	&format_attr_timestamp.attr,
+	&format_attr_retstack.attr,
 	NULL,
 };
 

include/linux/coresight-pmu.h

@@ -24,6 +24,7 @@
 /* ETMv3.5/PTM's ETMCR config bit */
 #define ETM_OPT_CYCACC  12
 #define ETM_OPT_TS      28
+#define ETM_OPT_RETSTK	29
 
 static inline int coresight_get_trace_id(int cpu)
 {

tools/include/linux/coresight-pmu.h

@@ -24,6 +24,7 @@
 /* ETMv3.5/PTM's ETMCR config bit */
 #define ETM_OPT_CYCACC  12
 #define ETM_OPT_TS      28
+#define ETM_OPT_RETSTK	29
 
 static inline int coresight_get_trace_id(int cpu)
 {