linux-gen: ticketlock: enable WFE on aarch64

Use WFE instruction on aarch64 to replace ISB instrution, making
threads waiting for their turn into low-power state. Performance
test with "odp_lock_perf" shows that it could reduce IPC while
maintain similar performance.

Signed-off-by: Fan Hong <fan.hong@arm.com>

platform/linux-generic/include/odp/api/plat/ticketlock_inlines.h

@@ -7,6 +7,10 @@
 #ifndef _ODP_PLAT_TICKETLOCK_INLINES_H_
 #define _ODP_PLAT_TICKETLOCK_INLINES_H_
 
+#if defined(__aarch64__)
+#include <odp_cpu.h>
+#endif
+
 #include <odp/api/atomic.h>
 #include <odp/api/cpu.h>
 
@@ -47,8 +51,15 @@ _ODP_INLINE void odp_ticketlock_lock(odp_ticketlock_t *ticketlock)
 
 	/* Spin waiting for our turn. Use load-acquire so that we acquire
 	 * all stores from the previous lock owner */
-	while (ticket != odp_atomic_load_acq_u32(&ticketlock->cur_ticket))
-		odp_cpu_pause();
+	#ifdef CONFIG_WFE
+		sevl();
+		while (wfe() && ticket !=
+			monitor32((uint32_t *)&ticketlock->cur_ticket, __ATOMIC_ACQUIRE)) {
+		}
+	#else
+		while (ticket != odp_atomic_load_acq_u32(&ticketlock->cur_ticket))
+			odp_cpu_pause();
+	#endif
 }
 
 _ODP_INLINE int odp_ticketlock_trylock(odp_ticketlock_t *tklock)