8:19 p.m.
Thanks for reviewing this patch Aneesh.
"Aneesh Kumar K.V" <aneesh.kumar(a)linux.ibm.com> writes:
Vaibhav Jain <vaibhav(a)linux.ibm.com> writes:
....
+
> +/* Papr-scm-header + payload expected with ND_CMD_CALL ioctl from libnvdimm */
> +struct nd_pdsm_cmd_pkg {
> + struct nd_cmd_pkg hdr; /* Package header containing sub-cmd */
> + __s32 cmd_status; /* Out: Sub-cmd status returned back */
> + __u16 payload_offset; /* In: offset from start of struct */
> + __u16 payload_version; /* In/Out: version of the payload */
> + __u8 payload[]; /* In/Out: Sub-cmd data buffer */
> +} __packed;
that payload_offset can be avoided if we prevent userspace to user a
different variant of nd_pdsm_cmd_pkg which different header. We can keep
things simpler if we can always find payload at
nd_pdsm_cmd_pkg->payload.
Had introduced this member to handle case where new
fields are added to
'struct nd_pdsm_cmd_pkg' without having to break the ABI. But agree with
the point that you made later that this can be simplified by replacing
'payload_offset' with a set of reserved variables. Will address this in
next iteration of this patchset.
> +
> +/*
> + * Methods to be embedded in ND_CMD_CALL request. These are sent to the kernel
> + * via 'nd_pdsm_cmd_pkg.hdr.nd_command' member of the ioctl struct
> + */
> +enum papr_scm_pdsm {
> + PAPR_SCM_PDSM_MIN = 0x0,
> + PAPR_SCM_PDSM_MAX,
> +};
> +
> +/* Convert a libnvdimm nd_cmd_pkg to pdsm specific pkg */
> +static inline struct nd_pdsm_cmd_pkg *nd_to_pdsm_cmd_pkg(struct nd_cmd_pkg *cmd)
> +{
> + return (struct nd_pdsm_cmd_pkg *) cmd;
> +}
> +
> +/* Return the payload pointer for a given pcmd */
> +static inline void *pdsm_cmd_to_payload(struct nd_pdsm_cmd_pkg *pcmd)
> +{
> + if (pcmd->hdr.nd_size_in == 0 && pcmd->hdr.nd_size_out == 0)
> + return NULL;
> + else
> + return (void *)((__u8 *) pcmd + pcmd->payload_offset);
> +}
> +
we need to make sure userspace is not passing a wrong payload_offset.
Agree, that
this function should have more strict checking for
payload_offset field. However will be getting rid of
'payload_offset' all together in the next iteration as you previously
suggested.
and in the next patch you do
+ /* Copy the health struct to the payload */
+ memcpy(pdsm_cmd_to_payload(pkg), &p->health, copysize);
+ pkg->hdr.nd_fw_size = copysize;
+
Yes this is already being done in the patchset and changes proposed to
this pdsm_cmd_to_payload() should not impact other patches as
pdsm_cmd_to_payload() abstracts rest of the code from how to access the
payload.
All this can be simplified if you can keep payload at
nd_pdsm_cmd_pkg->payload.
If you still want to have the ability to extend the header, then added a
reserved field similar to nd_cmd_pkg.
Agree to this and will address this in V8.
-aneesh
--
Cheers
~ Vaibhav