On Thu, Apr 08, 2021 at 02:51:01PM +0200, Lorenzo Bianconi wrote:
> From: Eelco Chaudron <echaudro@xxxxxxxxxx>
>
> This patch adds support for multi-buffer for the following helpers:
> - bpf_xdp_output()
> - bpf_perf_event_output()
>
> Signed-off-by: Eelco Chaudron <echaudro@xxxxxxxxxx>
> Signed-off-by: Lorenzo Bianconi <lorenzo@xxxxxxxxxx>
> ---
Also there is a typo in the commit message: bpd -> bpf.
> net/core/filter.c | 63 ++++++++-
> .../selftests/bpf/prog_tests/xdp_bpf2bpf.c | 127 ++++++++++++------
> .../selftests/bpf/progs/test_xdp_bpf2bpf.c | 3 +-
> 3 files changed, 149 insertions(+), 44 deletions(-)
>
> diff --git a/net/core/filter.c b/net/core/filter.c
> index c4eb1392f88e..c00f52ab2532 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -4549,10 +4549,56 @@ static const struct bpf_func_proto bpf_sk_ancestor_cgroup_id_proto = {
> };
> #endif
>
> -static unsigned long bpf_xdp_copy(void *dst_buff, const void *src_buff,
> +static unsigned long bpf_xdp_copy(void *dst_buff, const void *ctx,
> unsigned long off, unsigned long len)
> {
> - memcpy(dst_buff, src_buff + off, len);
> + struct xdp_buff *xdp = (struct xdp_buff *)ctx;
There is no need to cast a void pointer in C.
> + struct xdp_shared_info *xdp_sinfo;
> + unsigned long base_len;
> +
> + if (likely(!xdp->mb)) {
> + memcpy(dst_buff, xdp->data + off, len);
> + return 0;
> + }
> +
> + base_len = xdp->data_end - xdp->data;
Would a static inline int xdp_buff_head_len() be useful?
> + xdp_sinfo = xdp_get_shared_info_from_buff(xdp);
> + do {
> + const void *src_buff = NULL;
> + unsigned long copy_len = 0;
> +
> + if (off < base_len) {
> + src_buff = xdp->data + off;
> + copy_len = min(len, base_len - off);
> + } else {
> + unsigned long frag_off_total = base_len;
> + int i;
> +
> + for (i = 0; i < xdp_sinfo->nr_frags; i++) {
> + skb_frag_t *frag = &xdp_sinfo->frags[i];
> + unsigned long frag_len, frag_off;
> +
> + frag_len = xdp_get_frag_size(frag);
> + frag_off = off - frag_off_total;
> + if (frag_off < frag_len) {
> + src_buff = xdp_get_frag_address(frag) +
> + frag_off;
> + copy_len = min(len,
> + frag_len - frag_off);
> + break;
> + }
> + frag_off_total += frag_len;
> + }
> + }
> + if (!src_buff)
> + break;
> +
> + memcpy(dst_buff, src_buff, copy_len);
> + off += copy_len;
> + len -= copy_len;
> + dst_buff += copy_len;
> + } while (len);
> +
> return 0;
> }
