powerpc/perf: increase the perf HW events to 6

This change is required after the e6500 perf support has been added.
There are 6 counters in e6500 core instead of 4 in e500 core and
the MAX_HWEVENTS counter should be changed accordingly from 4 to 6.
Added also runtime check for counters overflow.

Signed-off-by: Catalin Udma <catalin.udma@freescale.com>
Signed-off-by: Lijun Pan <Lijun.Pan@freescale.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>

arch/powerpc/include/asm/perf_event_fsl_emb.h

@@ -13,7 +13,7 @@
 #include <linux/types.h>
 #include <asm/hw_irq.h>
 
-#define MAX_HWEVENTS 4
+#define MAX_HWEVENTS 6
 
 /* event flags */
 #define FSL_EMB_EVENT_VALID      1

arch/powerpc/perf/core-fsl-emb.c

@@ -462,6 +462,12 @@ static int fsl_emb_pmu_event_init(struct perf_event *event)
 	int num_restricted;
 	int i;
 
+	if (ppmu->n_counter > MAX_HWEVENTS) {
+		WARN(1, "No. of perf counters (%d) is higher than max array size(%d)\n",
+			ppmu->n_counter, MAX_HWEVENTS);
+		ppmu->n_counter = MAX_HWEVENTS;
+	}
+
 	switch (event->attr.type) {
 	case PERF_TYPE_HARDWARE:
 		ev = event->attr.config;