s390/barrier: make use of fast-bcr facility
If the kernel gets compiled for at least z196, make use of
the fast-BCR facility.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/include/asm/barrier.h b/arch/s390/include/asm/barrier.h
index 6993b20..10a5088 100644
--- a/arch/s390/include/asm/barrier.h
+++ b/arch/s390/include/asm/barrier.h
@@ -15,7 +15,12 @@
static inline void mb(void)
{
+#ifdef CONFIG_HAVE_MARCH_Z196_FEATURES
+ /* Fast-BCR without checkpoint synchronization */
+ asm volatile("bcr 14,0" : : : "memory");
+#else
asm volatile("bcr 15,0" : : : "memory");
+#endif
}
#define rmb() mb()
