diff options
| author | Jesper Dangaard Brouer <brouer@redhat.com> | 2022-07-11 17:04:22 +0300 |
|---|---|---|
| committer | Andrii Nakryiko <andrii@kernel.org> | 2022-07-12 07:14:35 +0300 |
| commit | 49705c4ab324654a7038fc843255140730477e04 (patch) | |
| tree | 641956d6ecc8a0854cf899c798af9523153200fc | |
| parent | efc9909fdce00a827a37609628223cd45bf95d0b (diff) | |
| download | linux-49705c4ab324654a7038fc843255140730477e04.tar.xz | |
samples/bpf: Fix xdp_redirect_map egress devmap prog
LLVM compiler optimized out the memcpy in xdp_redirect_map_egress,
which caused the Ethernet source MAC-addr to always be zero
when enabling the devmap egress prog via cmdline --load-egress.
Issue observed with LLVM version 14.0.0
- Shipped with Fedora 36 on target: x86_64-redhat-linux-gnu.
In verbose mode print the source MAC-addr in case xdp_devmap_attached
mode is used.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/165754826292.575614.5636444052787717159.stgit@firesoul
| -rw-r--r-- | samples/bpf/xdp_redirect_map.bpf.c | 6 | ||||
| -rw-r--r-- | samples/bpf/xdp_redirect_map_user.c | 9 |
2 files changed, 13 insertions, 2 deletions
diff --git a/samples/bpf/xdp_redirect_map.bpf.c b/samples/bpf/xdp_redirect_map.bpf.c index 415bac1758e3..8557c278df77 100644 --- a/samples/bpf/xdp_redirect_map.bpf.c +++ b/samples/bpf/xdp_redirect_map.bpf.c @@ -33,7 +33,7 @@ struct { } tx_port_native SEC(".maps"); /* store egress interface mac address */ -const volatile char tx_mac_addr[ETH_ALEN]; +const volatile __u8 tx_mac_addr[ETH_ALEN]; static __always_inline int xdp_redirect_map(struct xdp_md *ctx, void *redirect_map) { @@ -73,6 +73,7 @@ int xdp_redirect_map_egress(struct xdp_md *ctx) { void *data_end = (void *)(long)ctx->data_end; void *data = (void *)(long)ctx->data; + u8 *mac_addr = (u8 *) tx_mac_addr; struct ethhdr *eth = data; u64 nh_off; @@ -80,7 +81,8 @@ int xdp_redirect_map_egress(struct xdp_md *ctx) if (data + nh_off > data_end) return XDP_DROP; - __builtin_memcpy(eth->h_source, (const char *)tx_mac_addr, ETH_ALEN); + barrier_var(mac_addr); /* prevent optimizing out memcpy */ + __builtin_memcpy(eth->h_source, mac_addr, ETH_ALEN); return XDP_PASS; } diff --git a/samples/bpf/xdp_redirect_map_user.c b/samples/bpf/xdp_redirect_map_user.c index b6e4fc849577..c889a1394dc1 100644 --- a/samples/bpf/xdp_redirect_map_user.c +++ b/samples/bpf/xdp_redirect_map_user.c @@ -40,6 +40,8 @@ static const struct option long_options[] = { {} }; +static int verbose = 0; + int main(int argc, char **argv) { struct bpf_devmap_val devmap_val = {}; @@ -79,6 +81,7 @@ int main(int argc, char **argv) break; case 'v': sample_switch_mode(); + verbose = 1; break; case 's': mask |= SAMPLE_REDIRECT_MAP_CNT; @@ -134,6 +137,12 @@ int main(int argc, char **argv) ret = EXIT_FAIL; goto end_destroy; } + if (verbose) + printf("Egress ifindex:%d using src MAC %02x:%02x:%02x:%02x:%02x:%02x\n", + ifindex_out, + skel->rodata->tx_mac_addr[0], skel->rodata->tx_mac_addr[1], + skel->rodata->tx_mac_addr[2], skel->rodata->tx_mac_addr[3], + skel->rodata->tx_mac_addr[4], skel->rodata->tx_mac_addr[5]); } skel->rodata->from_match[0] = ifindex_in; |