[S390] fix futex_atomic_cmpxchg_inatomic

futex_atomic_cmpxchg_inatomic has the same bug as the other
atomic futex operations: the operation needs to be done in the
user address space, not the kernel address space. Add the missing
sacf 256 & sacf 0.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

include/asm-s390/futex.h

@@ -98,9 +98,10 @@ futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval)
 
 	if (! access_ok (VERIFY_WRITE, uaddr, sizeof(int)))
 		return -EFAULT;
-	asm volatile("   cs   %1,%4,0(%5)\n"
+	asm volatile("   sacf 256\n"
+		     "   cs   %1,%4,0(%5)\n"
 		     "0: lr   %0,%1\n"
-		     "1:\n"
+		     "1: sacf 0\n"
 #ifndef __s390x__
 		     ".section __ex_table,\"a\"\n"
 		     "   .align 4\n"