diff options
Diffstat (limited to 'samples/bpf/xdp_rxq_info_kern.c')
| -rw-r--r-- | samples/bpf/xdp_rxq_info_kern.c | 140 |
1 files changed, 140 insertions, 0 deletions
diff --git a/samples/bpf/xdp_rxq_info_kern.c b/samples/bpf/xdp_rxq_info_kern.c new file mode 100644 index 000000000..5e7459f9b --- /dev/null +++ b/samples/bpf/xdp_rxq_info_kern.c @@ -0,0 +1,140 @@ +/* SPDX-License-Identifier: GPL-2.0 + * Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc. + * + * Example howto extract XDP RX-queue info + */ +#include <uapi/linux/bpf.h> +#include <uapi/linux/if_ether.h> +#include <uapi/linux/in.h> +#include <bpf/bpf_helpers.h> + +/* Config setup from with userspace + * + * User-side setup ifindex in config_map, to verify that + * ctx->ingress_ifindex is correct (against configured ifindex) + */ +struct config { + __u32 action; + int ifindex; + __u32 options; +}; +enum cfg_options_flags { + NO_TOUCH = 0x0U, + READ_MEM = 0x1U, + SWAP_MAC = 0x2U, +}; + +struct { + __uint(type, BPF_MAP_TYPE_ARRAY); + __type(key, int); + __type(value, struct config); + __uint(max_entries, 1); +} config_map SEC(".maps"); + +/* Common stats data record (shared with userspace) */ +struct datarec { + __u64 processed; + __u64 issue; +}; + +struct { + __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY); + __type(key, u32); + __type(value, struct datarec); + __uint(max_entries, 1); +} stats_global_map SEC(".maps"); + +#define MAX_RXQs 64 + +/* Stats per rx_queue_index (per CPU) */ +struct { + __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY); + __type(key, u32); + __type(value, struct datarec); + __uint(max_entries, MAX_RXQs + 1); +} rx_queue_index_map SEC(".maps"); + +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) +{ + void *data_end = (void *)(long)ctx->data_end; + void *data = (void *)(long)ctx->data; + struct datarec *rec, *rxq_rec; + int ingress_ifindex; + struct config *config; + u32 key = 0; + + /* Global stats record */ + rec = bpf_map_lookup_elem(&stats_global_map, &key); + if (!rec) + return XDP_ABORTED; + rec->processed++; + + /* Accessing ctx->ingress_ifindex, cause BPF to rewrite BPF + * instructions inside kernel to access xdp_rxq->dev->ifindex + */ + ingress_ifindex = ctx->ingress_ifindex; + + config = bpf_map_lookup_elem(&config_map, &key); + if (!config) + return XDP_ABORTED; + + /* Simple test: check ctx provided ifindex is as expected */ + if (ingress_ifindex != config->ifindex) { + /* count this error case */ + rec->issue++; + return XDP_ABORTED; + } + + /* Update stats per rx_queue_index. Handle if rx_queue_index + * is larger than stats map can contain info for. + */ + key = ctx->rx_queue_index; + if (key >= MAX_RXQs) + key = MAX_RXQs; + rxq_rec = bpf_map_lookup_elem(&rx_queue_index_map, &key); + if (!rxq_rec) + return XDP_ABORTED; + rxq_rec->processed++; + if (key == MAX_RXQs) + rxq_rec->issue++; + + /* Default: Don't touch packet data, only count packets */ + if (unlikely(config->options & (READ_MEM|SWAP_MAC))) { + struct ethhdr *eth = data; + + if (eth + 1 > data_end) + return XDP_ABORTED; + + /* 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; +} + +char _license[] SEC("license") = "GPL"; |