From patchwork Tue Mar 21 23:28:09 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: 13183377 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 A301FC6FD20 for ; Tue, 21 Mar 2023 23:28:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229682AbjCUX2c (ORCPT ); Tue, 21 Mar 2023 19:28:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43802 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229524AbjCUX2b (ORCPT ); Tue, 21 Mar 2023 19:28:31 -0400 Received: from mx0b-00082601.pphosted.com (mx0b-00082601.pphosted.com [67.231.153.30]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A14BA76AE for ; Tue, 21 Mar 2023 16:28:30 -0700 (PDT) Received: from pps.filterd (m0148460.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 32LNGSJR023601 for ; Tue, 21 Mar 2023 16:28:30 -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=uQKgToFNYGD9uVmPouq5ZbZmbDZB9yDXMX2oAhLh8AE=; b=mRPIN+Bl689GMMqBOF1VQj5tJTajgRE9zlS3ts/nocYzJfcyPdGAIBmle+2zRVOhrJIV kS6va905AOgzf4wMKGS9kL6mIXu4Cvmvcu5IDet+mR0+SxoGlbSXtFkpCYq/3a+eqUWt rX/hcwsHFzHjG4tjbIwrhPefuypi2dV7jccA/T3XWB2sF9sXGbp1o2nbiZLqPSmFiKh9 pyiLIiUHK/LqEwWJhpU5mEmB2nDh0tHZBT1DjOdDx+0Ilt40UfrCPL9O2CAm24I6DlHb 3U7Y50H68GmrUN6mLhroisDpms8v+w1xF4dYTyV+cpfjYFEujUfRxvsq3yl4fTrt/TxC cg== Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3pf07cyqcb-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Tue, 21 Mar 2023 16:28:29 -0700 Received: from twshared21709.17.frc2.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:82::d) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.17; Tue, 21 Mar 2023 16:28:28 -0700 Received: by devbig931.frc1.facebook.com (Postfix, from userid 460691) id 6DC497EEB560; Tue, 21 Mar 2023 16:28:15 -0700 (PDT) From: Kui-Feng Lee To: , , , , , , CC: Kui-Feng Lee Subject: [PATCH bpf-next v10 4/8] libbpf: Create a bpf_link in bpf_map__attach_struct_ops(). Date: Tue, 21 Mar 2023 16:28:09 -0700 Message-ID: <20230321232813.3376064-5-kuifeng@meta.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230321232813.3376064-1-kuifeng@meta.com> References: <20230321232813.3376064-1-kuifeng@meta.com> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-ORIG-GUID: j14obUebU3ML_fRQKf696-K78mnanxWP X-Proofpoint-GUID: j14obUebU3ML_fRQKf696-K78mnanxWP 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=2023-03-21_11,2023-03-21_01,2023-02-09_01 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net bpf_map__attach_struct_ops() was creating a dummy bpf_link as a placeholder, but now it is constructing an authentic one by calling bpf_link_create() if the map has the BPF_F_LINK flag. You can flag a struct_ops map with BPF_F_LINK by calling bpf_map__set_map_flags(). Signed-off-by: Kui-Feng Lee Acked-by: Andrii Nakryiko --- tools/lib/bpf/libbpf.c | 95 +++++++++++++++++++++++++++++++----------- 1 file changed, 71 insertions(+), 24 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 4c34fbd7b5be..3b257d5170cb 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -116,6 +116,7 @@ static const char * const attach_type_name[] = { [BPF_SK_REUSEPORT_SELECT_OR_MIGRATE] = "sk_reuseport_select_or_migrate", [BPF_PERF_EVENT] = "perf_event", [BPF_TRACE_KPROBE_MULTI] = "trace_kprobe_multi", + [BPF_STRUCT_OPS] = "struct_ops", }; static const char * const link_type_name[] = { @@ -7683,6 +7684,37 @@ static int bpf_object__resolve_externs(struct bpf_object *obj, return 0; } +static void bpf_map_prepare_vdata(const struct bpf_map *map) +{ + struct bpf_struct_ops *st_ops; + __u32 i; + + st_ops = map->st_ops; + for (i = 0; i < btf_vlen(st_ops->type); i++) { + struct bpf_program *prog = st_ops->progs[i]; + void *kern_data; + int prog_fd; + + if (!prog) + continue; + + prog_fd = bpf_program__fd(prog); + kern_data = st_ops->kern_vdata + st_ops->kern_func_off[i]; + *(unsigned long *)kern_data = prog_fd; + } +} + +static int bpf_object_prepare_struct_ops(struct bpf_object *obj) +{ + int i; + + for (i = 0; i < obj->nr_maps; i++) + if (bpf_map__is_struct_ops(&obj->maps[i])) + bpf_map_prepare_vdata(&obj->maps[i]); + + return 0; +} + static int bpf_object_load(struct bpf_object *obj, int extra_log_level, const char *target_btf_path) { int err, i; @@ -7708,6 +7740,7 @@ static int bpf_object_load(struct bpf_object *obj, int extra_log_level, const ch err = err ? : bpf_object__relocate(obj, obj->btf_custom_path ? : target_btf_path); err = err ? : bpf_object__load_progs(obj, extra_log_level); err = err ? : bpf_object_init_prog_arrays(obj); + err = err ? : bpf_object_prepare_struct_ops(obj); if (obj->gen_loader) { /* reset FDs */ @@ -11572,22 +11605,30 @@ struct bpf_link *bpf_program__attach(const struct bpf_program *prog) return link; } +struct bpf_link_struct_ops { + struct bpf_link link; + int map_fd; +}; + static int bpf_link__detach_struct_ops(struct bpf_link *link) { + struct bpf_link_struct_ops *st_link; __u32 zero = 0; - if (bpf_map_delete_elem(link->fd, &zero)) - return -errno; + st_link = container_of(link, struct bpf_link_struct_ops, link); - return 0; + if (st_link->map_fd < 0) + /* w/o a real link */ + return bpf_map_delete_elem(link->fd, &zero); + + return close(link->fd); } struct bpf_link *bpf_map__attach_struct_ops(const struct bpf_map *map) { - struct bpf_struct_ops *st_ops; - struct bpf_link *link; - __u32 i, zero = 0; - int err; + struct bpf_link_struct_ops *link; + __u32 zero = 0; + int err, fd; if (!bpf_map__is_struct_ops(map) || map->fd == -1) return libbpf_err_ptr(-EINVAL); @@ -11596,31 +11637,37 @@ struct bpf_link *bpf_map__attach_struct_ops(const struct bpf_map *map) if (!link) return libbpf_err_ptr(-EINVAL); - st_ops = map->st_ops; - for (i = 0; i < btf_vlen(st_ops->type); i++) { - struct bpf_program *prog = st_ops->progs[i]; - void *kern_data; - int prog_fd; + /* kern_vdata should be prepared during the loading phase. */ + 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 && (!(map->def.map_flags & BPF_F_LINK) || err != -EBUSY)) { + free(link); + return libbpf_err_ptr(err); + } - if (!prog) - continue; + link->link.detach = bpf_link__detach_struct_ops; - prog_fd = bpf_program__fd(prog); - kern_data = st_ops->kern_vdata + st_ops->kern_func_off[i]; - *(unsigned long *)kern_data = prog_fd; + if (!(map->def.map_flags & BPF_F_LINK)) { + /* w/o a real link */ + link->link.fd = map->fd; + link->map_fd = -1; + return &link->link; } - err = bpf_map_update_elem(map->fd, &zero, st_ops->kern_vdata, 0); - if (err) { - err = -errno; + fd = bpf_link_create(map->fd, 0, BPF_STRUCT_OPS, NULL); + if (fd < 0) { free(link); - return libbpf_err_ptr(err); + return libbpf_err_ptr(fd); } - link->detach = bpf_link__detach_struct_ops; - link->fd = map->fd; + link->link.fd = fd; + link->map_fd = map->fd; - return link; + return &link->link; } typedef enum bpf_perf_event_ret (*bpf_perf_event_print_t)(struct perf_event_header *hdr,