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samples/bpf: xdp_rxq_info action XDP_TX must adjust MAC-addrs

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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>
This commit is contained in:
Jesper Dangaard Brouer 2018-06-25 16:27:48 +02:00 committed by Daniel Borkmann
parent 0d25c43ab9
commit 509fda105b
2 changed files with 36 additions and 1 deletions
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26
samples/bpf/xdp_rxq_info_kern.c
View file

@ -21,6 +21,7 @@ struct config {
enum cfg_options_flags {
NO_TOUCH = 0x0U,
READ_MEM = 0x1U,
SWAP_MAC = 0x2U,
};
struct bpf_map_def SEC("maps") config_map = {
.type = BPF_MAP_TYPE_ARRAY,
@ -52,6 +53,23 @@ struct bpf_map_def SEC("maps") rx_queue_index_map = {
.max_entries = MAX_RXQs + 1,
};
static __always_inline
void swap_src_dst_mac(void *data)
{
unsigned short *p = data;
unsigned short dst[3];
dst[0] = p[0];
dst[1] = p[1];
dst[2] = p[2];
p[0] = p[3];
p[1] = p[4];
p[2] = p[5];
p[3] = dst[0];
p[4] = dst[1];
p[5] = dst[2];
}
SEC("xdp_prog0")
int xdp_prognum0(struct xdp_md *ctx)
{
@ -98,7 +116,7 @@ int xdp_prognum0(struct xdp_md *ctx)
rxq_rec->issue++;
/* Default: Don't touch packet data, only count packets */
if (unlikely(config->options & READ_MEM)) {
if (unlikely(config->options & (READ_MEM|SWAP_MAC))) {
struct ethhdr *eth = data;
if (eth + 1 > data_end)
@ -107,6 +125,12 @@ int xdp_prognum0(struct xdp_md *ctx)
/* Avoid compiler removing this: Drop non 802.3 Ethertypes */
if (ntohs(eth->h_proto) < ETH_P_802_3_MIN)
return XDP_ABORTED;
/* XDP_TX requires changing MAC-addrs, else HW may drop.
* Can also be enabled with --swapmac (for test purposes)
*/
if (unlikely(config->options & SWAP_MAC))
swap_src_dst_mac(data);
}
return config->action;

11
samples/bpf/xdp_rxq_info_user.c
View file

@ -51,6 +51,7 @@ static const struct option long_options[] = {
{"no-separators", no_argument, NULL, 'z' },
{"action", required_argument, NULL, 'a' },
{"readmem", no_argument, NULL, 'r' },
{"swapmac", no_argument, NULL, 'm' },
{0, 0, NULL, 0 }
};
@ -72,6 +73,7 @@ struct config {
enum cfg_options_flags {
NO_TOUCH = 0x0U,
READ_MEM = 0x1U,
SWAP_MAC = 0x2U,
};
#define XDP_ACTION_MAX (XDP_TX + 1)
#define XDP_ACTION_MAX_STRLEN 11
@ -119,6 +121,8 @@ static char* options2str(enum cfg_options_flags flag)
{
if (flag == NO_TOUCH)
return "no_touch";
if (flag & SWAP_MAC)
return "swapmac";
if (flag & READ_MEM)
return "read";
fprintf(stderr, "ERR: Unknown config option flags");
@ -517,6 +521,9 @@ int main(int argc, char **argv)
case 'r':
cfg_options |= READ_MEM;
break;
case 'm':
cfg_options |= SWAP_MAC;
break;
case 'h':
error:
default:
@ -543,6 +550,10 @@ int main(int argc, char **argv)
}
}
cfg.action = action;
/* XDP_TX requires changing MAC-addrs, else HW may drop */
if (action == XDP_TX)
cfg_options |= SWAP_MAC;
cfg.options = cfg_options;
/* Trick to pretty printf with thousands separators use %' */