From patchwork Mon Dec 7 16:32:41 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lorenzo Bianconi X-Patchwork-Id: 11956355 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.0 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6398EC4361B for ; Mon, 7 Dec 2020 16:34:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 33CA7238E5 for ; Mon, 7 Dec 2020 16:34:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727623AbgLGQe2 (ORCPT ); Mon, 7 Dec 2020 11:34:28 -0500 Received: from mail.kernel.org ([198.145.29.99]:33136 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727017AbgLGQe1 (ORCPT ); Mon, 7 Dec 2020 11:34:27 -0500 From: Lorenzo Bianconi Authentication-Results: mail.kernel.org; dkim=permerror (bad message/signature format) To: bpf@vger.kernel.org, netdev@vger.kernel.org Cc: davem@davemloft.net, kuba@kernel.org, ast@kernel.org, daniel@iogearbox.net, shayagr@amazon.com, sameehj@amazon.com, john.fastabend@gmail.com, dsahern@kernel.org, brouer@redhat.com, echaudro@redhat.com, lorenzo.bianconi@redhat.com, jasowang@redhat.com Subject: [PATCH v5 bpf-next 12/14] bpf: add multi-buff support to the bpf_xdp_adjust_tail() API Date: Mon, 7 Dec 2020 17:32:41 +0100 Message-Id: <45d9ac7cd5895fa7af1ff54472257662ba25b877.1607349924.git.lorenzo@kernel.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net From: Eelco Chaudron This change adds support for tail growing and shrinking for XDP multi-buff. Signed-off-by: Eelco Chaudron Signed-off-by: Lorenzo Bianconi --- include/net/xdp.h | 5 ++++ net/core/filter.c | 63 +++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 68 insertions(+) diff --git a/include/net/xdp.h b/include/net/xdp.h index 76cfee6a40f7..09078ab6644c 100644 --- a/include/net/xdp.h +++ b/include/net/xdp.h @@ -137,6 +137,11 @@ static inline void xdp_set_frag_size(skb_frag_t *frag, u32 size) frag->bv_len = size; } +static inline unsigned int xdp_get_frag_tailroom(const skb_frag_t *frag) +{ + return PAGE_SIZE - xdp_get_frag_size(frag) - xdp_get_frag_offset(frag); +} + struct xdp_frame { void *data; u16 len; diff --git a/net/core/filter.c b/net/core/filter.c index 77001a35768f..4c4882d4d92c 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -3860,11 +3860,74 @@ static const struct bpf_func_proto bpf_xdp_adjust_head_proto = { .arg2_type = ARG_ANYTHING, }; +static int bpf_xdp_mb_adjust_tail(struct xdp_buff *xdp, int offset) +{ + struct xdp_shared_info *xdp_sinfo = xdp_get_shared_info_from_buff(xdp); + + if (unlikely(xdp_sinfo->nr_frags == 0)) + return -EINVAL; + + if (offset >= 0) { + skb_frag_t *frag = &xdp_sinfo->frags[xdp_sinfo->nr_frags - 1]; + int size; + + if (unlikely(offset > xdp_get_frag_tailroom(frag))) + return -EINVAL; + + size = xdp_get_frag_size(frag); + memset(xdp_get_frag_address(frag) + size, 0, offset); + xdp_set_frag_size(frag, size + offset); + xdp_sinfo->data_length += offset; + } else { + int i, frags_to_free = 0; + + offset = abs(offset); + + if (unlikely(offset > ((int)(xdp->data_end - xdp->data) + + xdp_sinfo->data_length - + ETH_HLEN))) + return -EINVAL; + + for (i = xdp_sinfo->nr_frags - 1; i >= 0 && offset > 0; i--) { + skb_frag_t *frag = &xdp_sinfo->frags[i]; + int size = xdp_get_frag_size(frag); + int shrink = min_t(int, offset, size); + + offset -= shrink; + if (likely(size - shrink > 0)) { + /* When updating the final fragment we have + * to adjust the data_length in line. + */ + xdp_sinfo->data_length -= shrink; + xdp_set_frag_size(frag, size - shrink); + break; + } + + /* When we free the fragments, + * xdp_return_frags_from_buff() will take care + * of updating the xdp share info data_length. + */ + frags_to_free++; + } + + if (unlikely(frags_to_free)) + xdp_return_num_frags_from_buff(xdp, frags_to_free); + + if (unlikely(offset > 0)) + xdp->data_end -= offset; + } + + return 0; +} + BPF_CALL_2(bpf_xdp_adjust_tail, struct xdp_buff *, xdp, int, offset) { void *data_hard_end = xdp_data_hard_end(xdp); /* use xdp->frame_sz */ void *data_end = xdp->data_end + offset; + if (unlikely(xdp->mb)) + return bpf_xdp_mb_adjust_tail(xdp, offset); + /* Notice that xdp_data_hard_end have reserved some tailroom */ if (unlikely(data_end > data_hard_end)) return -EINVAL;