[PATCH 5.16 118/186] s390/extable: fix exception table sorting

From: Greg Kroah-Hartman
Date: Mon Mar 07 2022 - 05:36:32 EST


From: Heiko Carstens <hca@xxxxxxxxxxxxx>

commit c194dad21025dfd043210912653baab823bdff67 upstream.

s390 has a swap_ex_entry_fixup function, however it is not being used
since common code expects a swap_ex_entry_fixup define. If it is not
defined the default implementation will be used. So fix this by adding
a proper define.
However also the implementation of the function must be fixed, since a
NULL value for handler has a special meaning and must not be adjusted.

Luckily all of this doesn't fix a real bug currently: the main extable
is correctly sorted during build time, and for runtime sorting there
is currently no case where the handler field is not NULL.

Fixes: 05a68e892e89 ("s390/kernel: expand exception table logic to allow new handling options")
Acked-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
Reviewed-by: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
Signed-off-by: Heiko Carstens <hca@xxxxxxxxxxxxx>
Signed-off-by: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/s390/include/asm/extable.h | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

--- a/arch/s390/include/asm/extable.h
+++ b/arch/s390/include/asm/extable.h
@@ -69,8 +69,13 @@ static inline void swap_ex_entry_fixup(s
{
a->fixup = b->fixup + delta;
b->fixup = tmp.fixup - delta;
- a->handler = b->handler + delta;
- b->handler = tmp.handler - delta;
+ a->handler = b->handler;
+ if (a->handler)
+ a->handler += delta;
+ b->handler = tmp.handler;
+ if (b->handler)
+ b->handler -= delta;
}
+#define swap_ex_entry_fixup swap_ex_entry_fixup

#endif