From 6fa889037fabf56f7e3dad48292ef1e30661eed2 Mon Sep 17 00:00:00 2001
From: Heiko Carstens <hca@linux.ibm.com>
Date: Tue, 7 Jan 2025 11:28:58 +0100
Subject: [PATCH] s390/futex: Fix FUTEX_OP_ANDN implementation
commit 26701574cee6777f867f89b4a5c667817e1ee0dd upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/s390/include/asm/futex.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/s390/include/asm/futex.h b/arch/s390/include/asm/futex.h
index eaeaeb3ff0be3..752a2310f0d6c 100644
--- 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",
--
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