On 01/03/2018 11:26 AM, Jesper Dangaard Brouer wrote:
> Now all XDP driver have been updated to setup xdp_rxq_info and assign
> this to xdp_buff->rxq. Thus, it is now safe to enable access to some
> of the xdp_rxq_info struct members.
>
> This patch extend xdp_md and expose UAPI to userspace for
> ingress_ifindex and rx_queue_index. Access happens via bpf
> instruction rewrite, that load data directly from struct xdp_rxq_info.
>
> * ingress_ifindex map to xdp_rxq_info->dev->ifindex
> * rx_queue_index map to xdp_rxq_info->queue_index
>
> Signed-off-by: Jesper Dangaard Brouer <[email protected]>
> Acked-by: Alexei Starovoitov <[email protected]>
> ---
> include/uapi/linux/bpf.h | 3 +++
> net/core/filter.c | 19 +++++++++++++++++++
> 2 files changed, 22 insertions(+)
>
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 69eabfcb9bdb..a6000a95d40e 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -899,6 +899,9 @@ struct xdp_md {
> __u32 data;
> __u32 data_end;
> __u32 data_meta;
> + /* Below access go though struct xdp_rxq_info */
> + __u32 ingress_ifindex; /* rxq->dev->ifindex */
> + __u32 rx_queue_index; /* rxq->queue_index */
> };
>
> enum sk_action {
> diff --git a/net/core/filter.c b/net/core/filter.c
> index 130b842c3a15..acdb94c0e97f 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -4304,6 +4304,25 @@ static u32 xdp_convert_ctx_access(enum bpf_access_type
> type,
> si->dst_reg, si->src_reg,
> offsetof(struct xdp_buff, data_end));
> break;
> + case offsetof(struct xdp_md, ingress_ifindex):
> + *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct xdp_buff, rxq),
> + si->dst_reg, si->src_reg,
> + offsetof(struct xdp_buff, rxq));
> + *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct xdp_rxq_info,
> dev),
> + si->dst_reg, si->dst_reg,
> + offsetof(struct xdp_rxq_info, dev));
> + *insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->dst_reg,
> + bpf_target_off(struct net_device,
> + ifindex, 4, target_size));
The bpf_target_off() is actually only used in the context of narrow ctx access.
This should just be:
*insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->dst_reg,
offsetof(struct net_device, ifindex));
> + break;
> + case offsetof(struct xdp_md, rx_queue_index):
> + *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct xdp_buff, rxq),
> + si->dst_reg, si->src_reg,
> + offsetof(struct xdp_buff, rxq));
> + *insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->dst_reg,
> + bpf_target_off(struct xdp_rxq_info,
> + queue_index, 4, target_size));
And here:
*insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->dst_reg,
offsetof(struct xdp_rxq_info, queue_index));
> + break;
> }
>
> return insn - insn_buf;
>
