[PATCH 5.10 169/491] s390/xor: Fix xor_xc_2() inline assembly constraints

Greg Kroah-Hartman
2026-04-13T16:49:58Z

From: Heiko Carstens <hca@linux.ibm.com>

[ Upstream commit f775276edc0c505dc0f782773796c189f31a1123 ]

The inline assembly constraints for xor_xc_2() are incorrect. "bytes",
"p1", and "p2" are input operands, while all three of them are modified
within the inline assembly. Given that the function consists only of this
inline assembly it seems unlikely that this may cause any problems, however
fix this in any case.

Fixes: 2cfc5f9ce7f5 ("s390/xor: optimized xor routing using the XC instruction")
Cc: stable@vger.kernel.org
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Link: https://lore.kernel.org/r/20260302133500.1560531-2-hca@linux.ibm.com
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/s390/lib/xor.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/s390/lib/xor.c
+++ b/arch/s390/lib/xor.c
@@ -28,8 +28,8 @@ static void xor_xc_2(unsigned long bytes
" j 3f\n"
"2: xc 0(1,%1),0(%2)\n"
"3:\n"
- : : "d" (bytes), "a" (p1), "a" (p2)
- : "0", "1", "cc", "memory");
+ : "+d" (bytes), "+a" (p1), "+a" (p2)
+ : : "0", "1", "cc", "memory");
}

static void xor_xc_3(unsigned long bytes, unsigned long *p1, unsigned long *p2,