From patchwork Wed Mar 8 00:50:47 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: 13165042 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 60B02C678D5 for ; Wed, 8 Mar 2023 00:53:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229706AbjCHAxq (ORCPT ); Tue, 7 Mar 2023 19:53:46 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57430 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229732AbjCHAxp (ORCPT ); Tue, 7 Mar 2023 19:53:45 -0500 Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com [67.231.145.42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4F7D1984C5 for ; Tue, 7 Mar 2023 16:53:43 -0800 (PST) Received: from pps.filterd (m0148461.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 32800e0e023549 for ; Tue, 7 Mar 2023 16:53:43 -0800 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=y19padtCiXBhWeTHeZaIQKUnIyNQqGgu8ga+f3l70xY=; b=iB6kwo7eje9fkWXPcdcMIevyKpn/ZkBlTxkqpkKiGh4F9sMSPBvI5BxWAuz/+jGSrbrA khD/3uo7GZmXjJA4Qks9krmlZ4NONgQ4RgSWD+KJEUdt7daJcsivoo5hvOA8OZjdDUty rvxmZzCZzpn4SaZRAYRAWF4sbr+nD9jrgkguaqi1A2htZWAdVwOQMZlyX4QK3Vux0OsW OPted16Faem880ay6yU5WDsdsrWNKu4cuRmJKZzHVM4M06pqoCO99h39lgVLQtHPWyg7 LelvZRGCjSX1FHkG0tlBp5rrFSj3PYYW3/gvdRCqhlp8oftrn5mk4Nu/pMusWRGdWHzt 0Q== Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3p6fekg8pq-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Tue, 07 Mar 2023 16:53:42 -0800 Received: from twshared33736.38.frc1.facebook.com (2620:10d:c085:108::4) by mail.thefacebook.com (2620:10d:c085:21d::6) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.17; Tue, 7 Mar 2023 16:53:41 -0800 Received: by devbig931.frc1.facebook.com (Postfix, from userid 460691) id A0A716C92E1C; Tue, 7 Mar 2023 16:50:54 -0800 (PST) From: Kui-Feng Lee To: , , , , , , CC: Kui-Feng Lee Subject: [PATCH bpf-next v5 5/8] bpf: Update the struct_ops of a bpf_link. Date: Tue, 7 Mar 2023 16:50:47 -0800 Message-ID: <20230308005050.255859-6-kuifeng@meta.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230308005050.255859-1-kuifeng@meta.com> References: <20230308005050.255859-1-kuifeng@meta.com> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-GUID: 5Le3zePsQguySn2_aY8JgE290AB9mWz3 X-Proofpoint-ORIG-GUID: 5Le3zePsQguySn2_aY8JgE290AB9mWz3 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=2023-03-07_18,2023-03-07_01,2023-02-09_01 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net By improving the BPF_LINK_UPDATE command of bpf(), it should allow you to conveniently switch between different struct_ops on a single bpf_link. This would enable smoother transitions from one struct_ops to another. The struct_ops maps passing along with BPF_LINK_UPDATE should have the BPF_F_LINK flag. Signed-off-by: Kui-Feng Lee --- include/linux/bpf.h | 1 + include/uapi/linux/bpf.h | 8 ++++-- kernel/bpf/bpf_struct_ops.c | 46 ++++++++++++++++++++++++++++++++++ kernel/bpf/syscall.c | 43 ++++++++++++++++++++++++++++--- tools/include/uapi/linux/bpf.h | 7 +++++- 5 files changed, 98 insertions(+), 7 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index afca6c526fe4..29d555a82bad 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1470,6 +1470,7 @@ struct bpf_link_ops { void (*show_fdinfo)(const struct bpf_link *link, struct seq_file *seq); int (*fill_link_info)(const struct bpf_link *link, struct bpf_link_info *info); + int (*update_map)(struct bpf_link *link, struct bpf_map *new_map); }; struct bpf_tramp_link { diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index f9fc7b8af3c4..edef9cf7d596 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -1555,8 +1555,12 @@ union bpf_attr { struct { /* struct used by BPF_LINK_UPDATE command */ __u32 link_fd; /* link fd */ - /* new program fd to update link with */ - __u32 new_prog_fd; + union { + /* new program fd to update link with */ + __u32 new_prog_fd; + /* new struct_ops map fd to update link with */ + __u32 new_map_fd; + }; __u32 flags; /* extra flags */ /* expected link's program fd; is specified only if * BPF_F_REPLACE flag is set in flags */ diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c index 5a7e86cf67b5..79e663869e51 100644 --- a/kernel/bpf/bpf_struct_ops.c +++ b/kernel/bpf/bpf_struct_ops.c @@ -775,10 +775,56 @@ static int bpf_struct_ops_map_link_fill_link_info(const struct bpf_link *link, return 0; } +static int bpf_struct_ops_map_link_update(struct bpf_link *link, struct bpf_map *new_map) +{ + struct bpf_struct_ops_value *kvalue; + struct bpf_struct_ops_map *st_map, *old_st_map; + struct bpf_struct_ops_link *st_link; + struct bpf_map *old_map; + int err = 0; + + if (new_map->map_type != BPF_MAP_TYPE_STRUCT_OPS || + !(new_map->map_flags & BPF_F_LINK)) + return -EINVAL; + + mutex_lock(&update_mutex); + + st_link = container_of(link, struct bpf_struct_ops_link, link); + + /* The new and old struct_ops must be the same type. */ + st_map = container_of(new_map, struct bpf_struct_ops_map, map); + + old_map = st_link->map; + old_st_map = container_of(old_map, struct bpf_struct_ops_map, map); + if (st_map->st_ops != old_st_map->st_ops || + /* Pair with smp_store_release() during map_update */ + smp_load_acquire(&st_map->kvalue.state) != BPF_STRUCT_OPS_STATE_READY) { + err = -EINVAL; + goto err_out; + } + + kvalue = &st_map->kvalue; + + err = st_map->st_ops->update(kvalue->data, old_st_map->kvalue.data); + if (err) + goto err_out; + + bpf_map_inc(new_map); + rcu_assign_pointer(st_link->map, new_map); + + bpf_map_put(old_map); + +err_out: + mutex_unlock(&update_mutex); + + return err; +} + static const struct bpf_link_ops bpf_struct_ops_map_lops = { .dealloc = bpf_struct_ops_map_link_dealloc, .show_fdinfo = bpf_struct_ops_map_link_show_fdinfo, .fill_link_info = bpf_struct_ops_map_link_fill_link_info, + .update_map = bpf_struct_ops_map_link_update, }; int bpf_struct_ops_link_create(union bpf_attr *attr) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 3a4503987a48..c087dd2e2c08 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -4658,6 +4658,30 @@ static int link_create(union bpf_attr *attr, bpfptr_t uattr) return ret; } +static int link_update_map(struct bpf_link *link, union bpf_attr *attr) +{ + struct bpf_map *new_map; + int ret = 0; + + new_map = bpf_map_get(attr->link_update.new_map_fd); + if (IS_ERR(new_map)) + return -EINVAL; + + if (new_map->map_type != BPF_MAP_TYPE_STRUCT_OPS) { + ret = -EINVAL; + goto out_put_map; + } + + if (link->ops->update_map) + ret = link->ops->update_map(link, new_map); + else + ret = -EINVAL; + +out_put_map: + bpf_map_put(new_map); + return ret; +} + #define BPF_LINK_UPDATE_LAST_FIELD link_update.old_prog_fd static int link_update(union bpf_attr *attr) @@ -4670,14 +4694,25 @@ static int link_update(union bpf_attr *attr) if (CHECK_ATTR(BPF_LINK_UPDATE)) return -EINVAL; - flags = attr->link_update.flags; - if (flags & ~BPF_F_REPLACE) - return -EINVAL; - link = bpf_link_get_from_fd(attr->link_update.link_fd); if (IS_ERR(link)) return PTR_ERR(link); + flags = attr->link_update.flags; + + if (link->ops->update_map) { + if (flags) /* always replace the existing one */ + ret = -EINVAL; + else + ret = link_update_map(link, attr); + goto out_put_link; + } + + if (flags & ~BPF_F_REPLACE) { + ret = -EINVAL; + goto out_put_link; + } + new_prog = bpf_prog_get(attr->link_update.new_prog_fd); if (IS_ERR(new_prog)) { ret = PTR_ERR(new_prog); diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 051b85525302..cfd1d2a9898d 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -1556,7 +1556,12 @@ union bpf_attr { struct { /* struct used by BPF_LINK_UPDATE command */ __u32 link_fd; /* link fd */ /* new program fd to update link with */ - __u32 new_prog_fd; + union { + /* new program fd to update link with */ + __u32 new_prog_fd; + /* new struct_ops map fd to update link with */ + __u32 new_map_fd; + }; __u32 flags; /* extra flags */ /* expected link's program fd; is specified only if * BPF_F_REPLACE flag is set in flags */