From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EE6AFC61DA4 for ; Wed, 15 Mar 2023 12:42:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232840AbjCOMmT (ORCPT ); Wed, 15 Mar 2023 08:42:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35818 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232795AbjCOMl7 (ORCPT ); Wed, 15 Mar 2023 08:41:59 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6B9C8CC2E for ; Wed, 15 Mar 2023 05:40:49 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id BB22661D73 for ; Wed, 15 Mar 2023 12:40:47 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CE11BC4339C; Wed, 15 Mar 2023 12:40:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1678884047; bh=NdxuVkQyGoTB2Km6sCRRjAePWobc0U5Xx8+hyXxwHgU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BUSxm/JPLhOISY7KH0sTzQJngKEsTqPj0Iq0EsouZAhjOaTJ2Y5tLR4El1vpAsl8Q uxkkZFyx+RfurnOiEHo0H+LTPswkK+tEpBXR1veJAMVjJk1dGCeBJeqUlCNVYppyiG S2Zn+jqjYTXhVDvkjPchnaClZo/YomTw0zYIWxzg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= , Alexander Lobakin , Martin KaFai Lau , Sasha Levin Subject: [PATCH 6.2 086/141] bpf, test_run: fix &xdp_frame misplacement for LIVE_FRAMES Date: Wed, 15 Mar 2023 13:13:09 +0100 Message-Id: <20230315115742.598212942@linuxfoundation.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230315115739.932786806@linuxfoundation.org> References: <20230315115739.932786806@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Alexander Lobakin [ Upstream commit 6c20822fada1b8adb77fa450d03a0d449686a4a9 ] &xdp_buff and &xdp_frame are bound in a way that xdp_buff->data_hard_start == xdp_frame It's always the case and e.g. xdp_convert_buff_to_frame() relies on this. IOW, the following: for (u32 i = 0; i < 0xdead; i++) { xdpf = xdp_convert_buff_to_frame(&xdp); xdp_convert_frame_to_buff(xdpf, &xdp); } shouldn't ever modify @xdpf's contents or the pointer itself. However, "live packet" code wrongly treats &xdp_frame as part of its context placed *before* the data_hard_start. With such flow, data_hard_start is sizeof(*xdpf) off to the right and no longer points to the XDP frame. Instead of replacing `sizeof(ctx)` with `offsetof(ctx, xdpf)` in several places and praying that there are no more miscalcs left somewhere in the code, unionize ::frm with ::data in a flex array, so that both starts pointing to the actual data_hard_start and the XDP frame actually starts being a part of it, i.e. a part of the headroom, not the context. A nice side effect is that the maximum frame size for this mode gets increased by 40 bytes, as xdp_buff::frame_sz includes everything from data_hard_start (-> includes xdpf already) to the end of XDP/skb shared info. Also update %MAX_PKT_SIZE accordingly in the selftests code. Leave it hardcoded for 64 bit && 4k pages, it can be made more flexible later on. Minor: align `&head->data` with how `head->frm` is assigned for consistency. Minor #2: rename 'frm' to 'frame' in &xdp_page_head while at it for clarity. (was found while testing XDP traffic generator on ice, which calls xdp_convert_frame_to_buff() for each XDP frame) Fixes: b530e9e1063e ("bpf: Add "live packet" mode for XDP in BPF_PROG_RUN") Acked-by: Toke Høiland-Jørgensen Signed-off-by: Alexander Lobakin Link: https://lore.kernel.org/r/20230215185440.4126672-1-aleksander.lobakin@intel.com Signed-off-by: Martin KaFai Lau Signed-off-by: Sasha Levin --- net/bpf/test_run.c | 29 +++++++++++++++---- .../bpf/prog_tests/xdp_do_redirect.c | 7 +++-- 2 files changed, 27 insertions(+), 9 deletions(-) diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c index 2723623429ac9..570ec242d9002 100644 --- a/net/bpf/test_run.c +++ b/net/bpf/test_run.c @@ -97,8 +97,11 @@ static bool bpf_test_timer_continue(struct bpf_test_timer *t, int iterations, struct xdp_page_head { struct xdp_buff orig_ctx; struct xdp_buff ctx; - struct xdp_frame frm; - u8 data[]; + union { + /* ::data_hard_start starts here */ + DECLARE_FLEX_ARRAY(struct xdp_frame, frame); + DECLARE_FLEX_ARRAY(u8, data); + }; }; struct xdp_test_data { @@ -116,6 +119,20 @@ struct xdp_test_data { #define TEST_XDP_FRAME_SIZE (PAGE_SIZE - sizeof(struct xdp_page_head)) #define TEST_XDP_MAX_BATCH 256 +#if BITS_PER_LONG == 64 && PAGE_SIZE == SZ_4K +/* tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c:%MAX_PKT_SIZE + * must be updated accordingly when any of these changes, otherwise BPF + * selftests will fail. + */ +#ifdef __s390x__ +#define TEST_MAX_PKT_SIZE 3216 +#else +#define TEST_MAX_PKT_SIZE 3408 +#endif +static_assert(SKB_WITH_OVERHEAD(TEST_XDP_FRAME_SIZE - XDP_PACKET_HEADROOM) == + TEST_MAX_PKT_SIZE); +#endif + static void xdp_test_run_init_page(struct page *page, void *arg) { struct xdp_page_head *head = phys_to_virt(page_to_phys(page)); @@ -132,8 +149,8 @@ static void xdp_test_run_init_page(struct page *page, void *arg) headroom -= meta_len; new_ctx = &head->ctx; - frm = &head->frm; - data = &head->data; + frm = head->frame; + data = head->data; memcpy(data + headroom, orig_ctx->data_meta, frm_len); xdp_init_buff(new_ctx, TEST_XDP_FRAME_SIZE, &xdp->rxq); @@ -223,7 +240,7 @@ static void reset_ctx(struct xdp_page_head *head) head->ctx.data = head->orig_ctx.data; head->ctx.data_meta = head->orig_ctx.data_meta; head->ctx.data_end = head->orig_ctx.data_end; - xdp_update_frame_from_buff(&head->ctx, &head->frm); + xdp_update_frame_from_buff(&head->ctx, head->frame); } static int xdp_recv_frames(struct xdp_frame **frames, int nframes, @@ -285,7 +302,7 @@ static int xdp_test_run_batch(struct xdp_test_data *xdp, struct bpf_prog *prog, head = phys_to_virt(page_to_phys(page)); reset_ctx(head); ctx = &head->ctx; - frm = &head->frm; + frm = head->frame; xdp->frame_cnt++; act = bpf_prog_run_xdp(prog, ctx); diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c b/tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c index ac70e871d62f8..9ce734a708b20 100644 --- a/tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c +++ b/tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c @@ -63,12 +63,13 @@ static int attach_tc_prog(struct bpf_tc_hook *hook, int fd) } /* The maximum permissible size is: PAGE_SIZE - sizeof(struct xdp_page_head) - - * sizeof(struct skb_shared_info) - XDP_PACKET_HEADROOM = 3368 bytes + * SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) - XDP_PACKET_HEADROOM = + * 3408 bytes for 64-byte cacheline and 3216 for 256-byte one. */ #if defined(__s390x__) -#define MAX_PKT_SIZE 3176 +#define MAX_PKT_SIZE 3216 #else -#define MAX_PKT_SIZE 3368 +#define MAX_PKT_SIZE 3408 #endif static void test_max_pkt_size(int fd) { -- 2.39.2