Re: [Xen-devel] [PATCH] pvcalls-front: 64-bit align flags

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 02/27/2018 02:54 PM, Stefano Stabellini wrote:
> We are using test_and_* operations on the status and flag fields of
> struct sock_mapping. However, these functions require the operand to be
> 64-bit aligned on arm64. Currently, only status is 64-bit aligned.
>
> Make flags 64-bit aligned by introducing an explicit padding field.
>
> Signed-off-by: Stefano Stabellini <stefano@xxxxxxxxxxx>
>
> diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c
> index ca5b773..aa07b2a 100644
> --- a/drivers/xen/pvcalls-front.c
> +++ b/drivers/xen/pvcalls-front.c
> @@ -78,6 +78,7 @@ struct sock_mapping {
>  #define PVCALLS_STATUS_BIND          1
>  #define PVCALLS_STATUS_LISTEN        2
>                       uint8_t status;
> +                     uint8_t pad[7];

Does this guarantee alignment (for either status or flag)?

-boris

>               /*
>                * Internal state-machine flags.
>                * Only one accept operation can be inflight for a socket.


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