s390/futex: Fix FUTEX_OP_ANDN implementation

The futex operation FUTEX_OP_ANDN is supposed to implement

*(int *)UADDR2 &= ~OPARG;

The s390 implementation just implements an AND instead of ANDN.
Add the missing bitwise not operation to oparg to fix this.

This is broken since nearly 19 years, so it looks like user space is
not making use of this operation.

Fixes: 3363fbdd6fb4 ("[PATCH] s390: futex atomic operations")
Cc: stable@vger.kernel.org
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

diff --git a/arch/s390/include/asm/futex.h b/arch/s390/include/asm/futex.h
index eaeaeb3..752a231 100644 (file)
--- a/arch/s390/include/asm/futex.h
+++ b/arch/s390/include/asm/futex.h
@@ -44,7 +44,7 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
                break;
        case FUTEX_OP_ANDN:
                __futex_atomic_op("lr %2,%1\nnr %2,%5\n",
-                                 ret, oldval, newval, uaddr, oparg);
+                                 ret, oldval, newval, uaddr, ~oparg);
                break;
        case FUTEX_OP_XOR:
                __futex_atomic_op("lr %2,%1\nxr %2,%5\n",