[S390] Fix futex_atomic_cmpxchg_std inline assembly.

Add missing exception table entry so that the kernel can handle
proctection exceptions as well on the cs instruction. Currently only
specification exceptions are handled correctly.
The missing entry allows user space to crash the kernel.

Cc: stable <stable@kernel.org>
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/lib/uaccess_std.c

@@ -293,10 +293,10 @@ int futex_atomic_cmpxchg_std(int __user *uaddr, int oldval, int newval)
 
 	asm volatile(
 		"   sacf 256\n"
-		"   cs   %1,%4,0(%5)\n"
-		"0: lr   %0,%1\n"
-		"1: sacf 0\n"
-		EX_TABLE(0b,1b)
+		"0: cs   %1,%4,0(%5)\n"
+		"1: lr   %0,%1\n"
+		"2: sacf 0\n"
+		EX_TABLE(0b,2b) EX_TABLE(1b,2b)
 		: "=d" (ret), "+d" (oldval), "=m" (*uaddr)
 		: "0" (-EFAULT), "d" (newval), "a" (uaddr), "m" (*uaddr)
 		: "cc", "memory" );