samples/bpf: xdp_rxq_info action XDP_TX must adjust MAC-addrs
XDP_TX requires also changing the MAC-addrs, else some hardware may drop the TX packet before reaching the wire. This was observed with driver mlx5. If xdp_rxq_info select --action XDP_TX the swapmac functionality is activated. It is also possible to manually enable via cmdline option --swapmac. This is practical if wanting to measure the overhead of writing/updating payload for other action types. Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Toke Høiland-Jørgensen <toke@toke.dk> Acked-by: Song Liu <songliubraving@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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@ -21,6 +21,7 @@ struct config {
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enum cfg_options_flags {
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NO_TOUCH = 0x0U,
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READ_MEM = 0x1U,
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SWAP_MAC = 0x2U,
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};
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struct bpf_map_def SEC("maps") config_map = {
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.type = BPF_MAP_TYPE_ARRAY,
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@ -52,6 +53,23 @@ struct bpf_map_def SEC("maps") rx_queue_index_map = {
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.max_entries = MAX_RXQs + 1,
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};
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static __always_inline
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void swap_src_dst_mac(void *data)
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{
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unsigned short *p = data;
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unsigned short dst[3];
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dst[0] = p[0];
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dst[1] = p[1];
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dst[2] = p[2];
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p[0] = p[3];
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p[1] = p[4];
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p[2] = p[5];
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p[3] = dst[0];
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p[4] = dst[1];
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p[5] = dst[2];
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}
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SEC("xdp_prog0")
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int xdp_prognum0(struct xdp_md *ctx)
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{
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@ -98,7 +116,7 @@ int xdp_prognum0(struct xdp_md *ctx)
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rxq_rec->issue++;
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/* Default: Don't touch packet data, only count packets */
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if (unlikely(config->options & READ_MEM)) {
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if (unlikely(config->options & (READ_MEM|SWAP_MAC))) {
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struct ethhdr *eth = data;
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if (eth + 1 > data_end)
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@ -107,6 +125,12 @@ int xdp_prognum0(struct xdp_md *ctx)
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/* Avoid compiler removing this: Drop non 802.3 Ethertypes */
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if (ntohs(eth->h_proto) < ETH_P_802_3_MIN)
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return XDP_ABORTED;
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/* XDP_TX requires changing MAC-addrs, else HW may drop.
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* Can also be enabled with --swapmac (for test purposes)
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*/
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if (unlikely(config->options & SWAP_MAC))
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swap_src_dst_mac(data);
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}
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return config->action;
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@ -51,6 +51,7 @@ static const struct option long_options[] = {
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{"no-separators", no_argument, NULL, 'z' },
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{"action", required_argument, NULL, 'a' },
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{"readmem", no_argument, NULL, 'r' },
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{"swapmac", no_argument, NULL, 'm' },
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{0, 0, NULL, 0 }
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};
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@ -72,6 +73,7 @@ struct config {
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enum cfg_options_flags {
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NO_TOUCH = 0x0U,
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READ_MEM = 0x1U,
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SWAP_MAC = 0x2U,
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};
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#define XDP_ACTION_MAX (XDP_TX + 1)
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#define XDP_ACTION_MAX_STRLEN 11
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@ -119,6 +121,8 @@ static char* options2str(enum cfg_options_flags flag)
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{
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if (flag == NO_TOUCH)
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return "no_touch";
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if (flag & SWAP_MAC)
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return "swapmac";
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if (flag & READ_MEM)
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return "read";
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fprintf(stderr, "ERR: Unknown config option flags");
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@ -517,6 +521,9 @@ int main(int argc, char **argv)
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case 'r':
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cfg_options |= READ_MEM;
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break;
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case 'm':
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cfg_options |= SWAP_MAC;
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break;
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case 'h':
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error:
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default:
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@ -543,6 +550,10 @@ int main(int argc, char **argv)
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}
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}
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cfg.action = action;
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/* XDP_TX requires changing MAC-addrs, else HW may drop */
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if (action == XDP_TX)
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cfg_options |= SWAP_MAC;
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cfg.options = cfg_options;
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/* Trick to pretty printf with thousands separators use %' */
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