Introduce the XDP_METADATA_SIZE macro to ensure that user applications can consistently retrieve the correct location of struct xdp_meta.
Prior to this commit, the XDP program adjusted the data_meta backward by the size of struct xdp_meta, while the user application retrieved the data by calculating backward from the data pointer. This approach only worked if xdp_buff->data_meta was equal to xdp_buff->data before calling bpf_xdp_adjust_meta. With the introduction of XDP_METADATA_SIZE, both the XDP program and user application now calculate and identify the location of struct xdp_meta from the data pointer. This ensures the implementation remains functional even when there is device-reserved metadata, making the tests more portable across different NICs. Signed-off-by: Song Yoong Siang <[email protected]> --- tools/testing/selftests/bpf/prog_tests/xdp_metadata.c | 2 +- tools/testing/selftests/bpf/progs/xdp_hw_metadata.c | 10 +++++++++- tools/testing/selftests/bpf/progs/xdp_metadata.c | 8 +++++++- tools/testing/selftests/bpf/xdp_hw_metadata.c | 2 +- tools/testing/selftests/bpf/xdp_metadata.h | 7 +++++++ 5 files changed, 25 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_metadata.c b/tools/testing/selftests/bpf/prog_tests/xdp_metadata.c index 19f92affc2da..8d6c2633698b 100644 --- a/tools/testing/selftests/bpf/prog_tests/xdp_metadata.c +++ b/tools/testing/selftests/bpf/prog_tests/xdp_metadata.c @@ -302,7 +302,7 @@ static int verify_xsk_metadata(struct xsk *xsk, bool sent_from_af_xdp) /* custom metadata */ - meta = data - sizeof(struct xdp_meta); + meta = data - XDP_METADATA_SIZE; if (!ASSERT_NEQ(meta->rx_timestamp, 0, "rx_timestamp")) return -1; diff --git a/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c b/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c index 330ece2eabdb..72242ac1cdcd 100644 --- a/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c +++ b/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c @@ -27,6 +27,7 @@ extern int bpf_xdp_metadata_rx_vlan_tag(const struct xdp_md *ctx, SEC("xdp.frags") int rx(struct xdp_md *ctx) { + int metalen_used, metalen_to_adjust; void *data, *data_meta, *data_end; struct ipv6hdr *ip6h = NULL; struct udphdr *udp = NULL; @@ -72,7 +73,14 @@ int rx(struct xdp_md *ctx) return XDP_PASS; } - err = bpf_xdp_adjust_meta(ctx, -(int)sizeof(struct xdp_meta)); + metalen_used = ctx->data - ctx->data_meta; + metalen_to_adjust = XDP_METADATA_SIZE - metalen_used; + if (metalen_to_adjust < (int)sizeof(struct xdp_meta)) { + __sync_add_and_fetch(&pkts_skip, 1); + return XDP_PASS; + } + + err = bpf_xdp_adjust_meta(ctx, -metalen_to_adjust); if (err) { __sync_add_and_fetch(&pkts_fail, 1); return XDP_PASS; diff --git a/tools/testing/selftests/bpf/progs/xdp_metadata.c b/tools/testing/selftests/bpf/progs/xdp_metadata.c index 09bb8a038d52..a0ba4ef4bbd8 100644 --- a/tools/testing/selftests/bpf/progs/xdp_metadata.c +++ b/tools/testing/selftests/bpf/progs/xdp_metadata.c @@ -37,6 +37,7 @@ extern int bpf_xdp_metadata_rx_vlan_tag(const struct xdp_md *ctx, SEC("xdp") int rx(struct xdp_md *ctx) { + int metalen_used, metalen_to_adjust; void *data, *data_meta, *data_end; struct ipv6hdr *ip6h = NULL; struct ethhdr *eth = NULL; @@ -73,7 +74,12 @@ int rx(struct xdp_md *ctx) /* Reserve enough for all custom metadata. */ - ret = bpf_xdp_adjust_meta(ctx, -(int)sizeof(struct xdp_meta)); + metalen_used = ctx->data - ctx->data_meta; + metalen_to_adjust = XDP_METADATA_SIZE - metalen_used; + if (metalen_to_adjust < (int)sizeof(struct xdp_meta)) + return XDP_DROP; + + ret = bpf_xdp_adjust_meta(ctx, -metalen_to_adjust); if (ret != 0) return XDP_DROP; diff --git a/tools/testing/selftests/bpf/xdp_hw_metadata.c b/tools/testing/selftests/bpf/xdp_hw_metadata.c index 3d8de0d4c96a..a529d55d4ff4 100644 --- a/tools/testing/selftests/bpf/xdp_hw_metadata.c +++ b/tools/testing/selftests/bpf/xdp_hw_metadata.c @@ -223,7 +223,7 @@ static void verify_xdp_metadata(void *data, clockid_t clock_id) { struct xdp_meta *meta; - meta = data - sizeof(*meta); + meta = data - XDP_METADATA_SIZE; if (meta->hint_valid & XDP_META_FIELD_RSS) printf("rx_hash: 0x%X with RSS type:0x%X\n", diff --git a/tools/testing/selftests/bpf/xdp_metadata.h b/tools/testing/selftests/bpf/xdp_metadata.h index 87318ad1117a..2dfd3bf5e7bb 100644 --- a/tools/testing/selftests/bpf/xdp_metadata.h +++ b/tools/testing/selftests/bpf/xdp_metadata.h @@ -50,3 +50,10 @@ struct xdp_meta { }; enum xdp_meta_field hint_valid; }; + +/* XDP_METADATA_SIZE must be at least the size of struct xdp_meta. An additional + * 32 bytes of padding is included as a conservative measure to accommodate any + * metadata areas reserved by Ethernet devices. If the device-reserved metadata + * exceeds 32 bytes, this value will need adjustment. + */ +#define XDP_METADATA_SIZE (sizeof(struct xdp_meta) + 32) -- 2.34.1
