sparc64: Add membar to Niagara2 memcpy code.

[ Upstream commit 5aa4ecfd0ddb1e6dcd1c886e6c49677550f581aa ]

This is the prevent previous stores from overlapping the block stores
done by the memcpy loop.

Based upon a glibc patch by Jose E. Marchesi

Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/arch/sparc/lib/NG2memcpy.S b/arch/sparc/lib/NG2memcpy.S
index 0aed756..e993fc8 100644
--- a/arch/sparc/lib/NG2memcpy.S
+++ b/arch/sparc/lib/NG2memcpy.S
@@ -236,6 +236,7 @@
 	 */
 	VISEntryHalf
 
+	membar		#Sync
 	alignaddr	%o1, %g0, %g0
 
 	add		%o1, (64 - 1), %o4