2018-03-01 02:06:34

by Stefano Stabellini

Subject: [PATCH v2] pvcalls-front: 64-bit align flags

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 status and flags explicitly 64-bit aligned.

Signed-off-by: Stefano Stabellini <[email protected]>

---
Changes in v2:
- use __attribute__((aligned(8)))
- add comments

diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c
index ca5b773..582929e 100644
--- a/drivers/xen/pvcalls-front.c
+++ b/drivers/xen/pvcalls-front.c
@@ -73,20 +73,25 @@ struct sock_mapping {
wait_queue_head_t inflight_conn_req;
} active;
struct {
- /* Socket status */
+ /*
+ * Socket status, needs to be 64-bit aligned due to the
+ * test_and_* functions which have this requirement on arm64.
+ */
#define PVCALLS_STATUS_UNINITALIZED 0
#define PVCALLS_STATUS_BIND 1
#define PVCALLS_STATUS_LISTEN 2
- uint8_t status;
+ uint8_t status __attribute__((aligned(8)));
/*
* Internal state-machine flags.
* Only one accept operation can be inflight for a socket.
* Only one poll operation can be inflight for a given socket.
+ * flags needs to be 64-bit aligned due to the test_and_*
+ * functions which have this requirement on arm64.
*/
#define PVCALLS_FLAG_ACCEPT_INFLIGHT 0
#define PVCALLS_FLAG_POLL_INFLIGHT 1
#define PVCALLS_FLAG_POLL_RET 2
- uint8_t flags;
+ uint8_t flags __attribute__((aligned(8)));
uint32_t inflight_req_id;
struct sock_mapping *accept_map;
wait_queue_head_t inflight_accept_req;

2018-03-01 02:16:53

by Boris Ostrovsky

Subject: Re: [PATCH v2] pvcalls-front: 64-bit align flags

On 02/28/2018 09:05 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 status and flags explicitly 64-bit aligned.
>
> Signed-off-by: Stefano Stabellini <[email protected]>


Reviewed-by: Boris Ostrovsky <[email protected]>

2018-03-01 06:25:51

by Jürgen Groß

Subject: Re: [PATCH v2] pvcalls-front: 64-bit align flags

On 01/03/18 03:05, 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 status and flags explicitly 64-bit aligned.
>
> Signed-off-by: Stefano Stabellini <[email protected]>

Committed to xen/tip for-linus-4.16a


Juergen