From patchwork Thu Mar 23 03:24:03 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kui-Feng Lee X-Patchwork-Id: 13184864 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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1BF42C6FD1C for ; Thu, 23 Mar 2023 03:26:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229951AbjCWD0z (ORCPT ); Wed, 22 Mar 2023 23:26:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40194 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230025AbjCWD0y (ORCPT ); Wed, 22 Mar 2023 23:26:54 -0400 Received: from mx0b-00082601.pphosted.com (mx0b-00082601.pphosted.com [67.231.153.30]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C5C1C25B9D for ; Wed, 22 Mar 2023 20:26:52 -0700 (PDT) Received: from pps.filterd (m0109332.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 32N0gYK8014571 for ; Wed, 22 Mar 2023 20:26:52 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=meta.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding : content-type; s=s2048-2021-q4; bh=AKezN9d4fSXDPDtG0D4z5lnf7aHl8j/Tcaf5rYqpKqg=; b=d1ywR1CH59YKanr+vMdhvrFuTSttelR7lTX8divSpNl1UBgXOHpcS8eHy9ppFvRMJ50h HnmXonwffmmKgmcl1FmadMFKlaoER3fVC82d9xvYwZ3ZxhPTUXSaMDRMThhygy1zX0Jj gZ2ngkjdeHri5nv3WPM18OUwVgID0FRLOHOih5JPxl621f13+knzUFioJKjh1JzNvUvF 5CcNzUq8oKGQLRXqzqxM96V7cQA034GPTXvKgm1FU1c5jWA6zux+BvH9q2yv5J04e07Y Wv5++fKdz5SgGMAZP9fkcsrR5AYnIgP5U1Bjs6cEb+CiLu6YwGscVATtbqZt+Zb/2Kyq UA== Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3pfuek75uc-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Wed, 22 Mar 2023 20:26:51 -0700 Received: from twshared34471.14.frc2.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:83::6) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.17; Wed, 22 Mar 2023 20:26:50 -0700 Received: by devbig931.frc1.facebook.com (Postfix, from userid 460691) id 4D63B8086DAF; Wed, 22 Mar 2023 20:24:07 -0700 (PDT) From: Kui-Feng Lee To: , , , , , , CC: Kui-Feng Lee Subject: [PATCH bpf-next v12 6/8] libbpf: Update a bpf_link with another struct_ops. Date: Wed, 22 Mar 2023 20:24:03 -0700 Message-ID: <20230323032405.3735486-7-kuifeng@meta.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230323032405.3735486-1-kuifeng@meta.com> References: <20230323032405.3735486-1-kuifeng@meta.com> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-ORIG-GUID: jHrg_bCZJ-S_rFfTp_f92kT_96-lcaCy X-Proofpoint-GUID: jHrg_bCZJ-S_rFfTp_f92kT_96-lcaCy X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.254,Aquarius:18.0.942,Hydra:6.0.573,FMLib:17.11.170.22 definitions=2023-03-22_21,2023-03-22_01,2023-02-09_01 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Introduce bpf_link__update_map(), which allows to atomically update underlying struct_ops implementation for given struct_ops BPF link. Also add old_map_fd to struct bpf_link_update_opts to handle BPF_F_REPLACE feature. Signed-off-by: Kui-Feng Lee --- tools/lib/bpf/bpf.c | 8 +++++++- tools/lib/bpf/bpf.h | 3 ++- tools/lib/bpf/libbpf.c | 35 +++++++++++++++++++++++++++++++++++ tools/lib/bpf/libbpf.h | 1 + tools/lib/bpf/libbpf.map | 1 + 5 files changed, 46 insertions(+), 2 deletions(-) diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c index e750b6f5fcc3..767035900354 100644 --- a/tools/lib/bpf/bpf.c +++ b/tools/lib/bpf/bpf.c @@ -794,11 +794,17 @@ int bpf_link_update(int link_fd, int new_prog_fd, if (!OPTS_VALID(opts, bpf_link_update_opts)) return libbpf_err(-EINVAL); + if (OPTS_GET(opts, old_prog_fd, 0) && OPTS_GET(opts, old_map_fd, 0)) + return libbpf_err(-EINVAL); + memset(&attr, 0, attr_sz); attr.link_update.link_fd = link_fd; attr.link_update.new_prog_fd = new_prog_fd; attr.link_update.flags = OPTS_GET(opts, flags, 0); - attr.link_update.old_prog_fd = OPTS_GET(opts, old_prog_fd, 0); + if (OPTS_GET(opts, old_prog_fd, 0)) + attr.link_update.old_prog_fd = OPTS_GET(opts, old_prog_fd, 0); + else if (OPTS_GET(opts, old_map_fd, 0)) + attr.link_update.old_map_fd = OPTS_GET(opts, old_map_fd, 0); ret = sys_bpf(BPF_LINK_UPDATE, &attr, attr_sz); return libbpf_err_errno(ret); diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h index f0f786373238..b073e73439ef 100644 --- a/tools/lib/bpf/bpf.h +++ b/tools/lib/bpf/bpf.h @@ -336,8 +336,9 @@ struct bpf_link_update_opts { size_t sz; /* size of this struct for forward/backward compatibility */ __u32 flags; /* extra flags */ __u32 old_prog_fd; /* expected old program FD */ + __u32 old_map_fd; /* expected old map FD */ }; -#define bpf_link_update_opts__last_field old_prog_fd +#define bpf_link_update_opts__last_field old_map_fd LIBBPF_API int bpf_link_update(int link_fd, int new_prog_fd, const struct bpf_link_update_opts *opts); diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 4ff82baba0ea..2b5ea2500b80 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -11677,6 +11677,41 @@ struct bpf_link *bpf_map__attach_struct_ops(const struct bpf_map *map) return &link->link; } +/* + * Swap the back struct_ops of a link with a new struct_ops map. + */ +int bpf_link__update_map(struct bpf_link *link, const struct bpf_map *map) +{ + struct bpf_link_struct_ops *st_ops_link; + __u32 zero = 0; + int err; + + if (!bpf_map__is_struct_ops(map) || map->fd < 0) + return -EINVAL; + + st_ops_link = container_of(link, struct bpf_link_struct_ops, link); + /* Ensure the type of a link is correct */ + if (st_ops_link->map_fd < 0) + return -EINVAL; + + err = bpf_map_update_elem(map->fd, &zero, map->st_ops->kern_vdata, 0); + /* It can be EBUSY if the map has been used to create or + * update a link before. We don't allow updating the value of + * a struct_ops once it is set. That ensures that the value + * never changed. So, it is safe to skip EBUSY. + */ + if (err && err != -EBUSY) + return err; + + err = bpf_link_update(link->fd, map->fd, NULL); + if (err < 0) + return err; + + st_ops_link->map_fd = map->fd; + + return 0; +} + typedef enum bpf_perf_event_ret (*bpf_perf_event_print_t)(struct perf_event_header *hdr, void *private_data); diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index db4992a036f8..1615e55e2e79 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -719,6 +719,7 @@ bpf_program__attach_freplace(const struct bpf_program *prog, struct bpf_map; LIBBPF_API struct bpf_link *bpf_map__attach_struct_ops(const struct bpf_map *map); +LIBBPF_API int bpf_link__update_map(struct bpf_link *link, const struct bpf_map *map); struct bpf_iter_attach_opts { size_t sz; /* size of this struct for forward/backward compatibility */ diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map index 50dde1f6521e..a5aa3a383d69 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map @@ -386,6 +386,7 @@ LIBBPF_1.1.0 { LIBBPF_1.2.0 { global: bpf_btf_get_info_by_fd; + bpf_link__update_map; bpf_link_get_info_by_fd; bpf_map_get_info_by_fd; bpf_prog_get_info_by_fd;