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 X-Spam-Level: X-Spam-Status: No, score=-6.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=ham 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 68200C2BA83 for ; Thu, 13 Feb 2020 17:42:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3717D206ED for ; Thu, 13 Feb 2020 17:42:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="spwkzztg" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727705AbgBMRmV (ORCPT ); Thu, 13 Feb 2020 12:42:21 -0500 Received: from mail-qk1-f196.google.com ([209.85.222.196]:43387 "EHLO mail-qk1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726282AbgBMRmV (ORCPT ); Thu, 13 Feb 2020 12:42:21 -0500 Received: by mail-qk1-f196.google.com with SMTP id p7so6474945qkh.10; Thu, 13 Feb 2020 09:42:20 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=0SeRIRwAxXCgkVIkqnHKnVkNwgSm44M/L7Ref4jNpIk=; b=spwkzztgIQeIuO4waZxR636AO2fypTRBRalqcpVGHE09aC/6U1WNQVuj7QVf+nLoRn FkcEXooRYeZhg7zKIMZk02VgAoAhGWYkrPAbycUZJ9LBO8voxNthFdJvOfR7iXivwTMA vVH9wukDV8r89eu1Gpk1O4rmydZYsmkQ8G9U7M7AIIEtjU8CTYnWrg8sgwIh2BFwjIKx jYj08tm26pqn7KeuedkozsDoEIGhjsXovv46FqbJquMS2IyFUPx4rrAorBM3D542IY4A X1fz+Kw+9D4aZ+EGLY6gzQxT63WDgr1rj1eqn9xw2E3ooN7YnISUtAM9WzGOPngfkm3P vQJw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=0SeRIRwAxXCgkVIkqnHKnVkNwgSm44M/L7Ref4jNpIk=; b=Kfr1r3Rla3ff04v0ZmNJvia66cw+kduO0cXhJlArsTM2lU4eRf7Bx5DMBJy7Oflsyg 1+gTbU65Yfn8FpcikAuqGszKVPZkurD7Ie3w7tgiaoSUeOykr8hGHs84042Hrr+Vzxqf CPJNOy83dRhRlNbHqG7qyAPvJ4UNuEH877WCnjMV7hQW+uXD4sD79jtU75txbsGrrw8Q eip+ROo0eOMurwrRsfcPhlarioH59j24tyLkwlPXTBZRTojulqQYFvs+Mt2OUNh56j4N iRnZsc9m9ZmB2RLNl9/WSj6cbqxxdjCAtCx5XM7vuxlYXCj2dhvHIbBa0cbblNJbs7gG qOMg== X-Gm-Message-State: APjAAAVwO7Hqx78oV6GcNjCgYlbmqalrEZLsrzse2gXofY2+GRczLhyM +N+Ym6tVE3VmOojZ1/pD83ZO9+heC/nuVfqT0uA= X-Google-Smtp-Source: APXvYqx1nl6f2Zr1d51JuwBUaBpaNIgNfEMGseiSHJsucuRgkIjD3os20mX9S6GucebEwh+B55lENgq0kuxAqDhM2Zo= X-Received: by 2002:a37:785:: with SMTP id 127mr17031600qkh.437.1581615739921; Thu, 13 Feb 2020 09:42:19 -0800 (PST) MIME-Version: 1.0 References: <158160616195.80320.5636088335810242866.stgit@xdp-tutorial> In-Reply-To: <158160616195.80320.5636088335810242866.stgit@xdp-tutorial> From: Andrii Nakryiko Date: Thu, 13 Feb 2020 09:42:07 -0800 Message-ID: Subject: Re: [PATCH bpf-next v2] libbpf: Add support for dynamic program attach target To: Eelco Chaudron Cc: bpf , "David S. Miller" , Networking , Alexei Starovoitov , Daniel Borkmann , Martin Lau , Song Liu , Yonghong Song , Andrii Nakryiko , =?UTF-8?B?VG9rZSBIw7hpbGFuZC1Kw7hyZ2Vuc2Vu?= Content-Type: text/plain; charset="UTF-8" Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Thu, Feb 13, 2020 at 7:05 AM Eelco Chaudron wrote: > > Currently when you want to attach a trace program to a bpf program > the section name needs to match the tracepoint/function semantics. > > However the addition of the bpf_program__set_attach_target() API > allows you to specify the tracepoint/function dynamically. > > The call flow would look something like this: > > xdp_fd = bpf_prog_get_fd_by_id(id); > trace_obj = bpf_object__open_file("func.o", NULL); > prog = bpf_object__find_program_by_title(trace_obj, > "fentry/myfunc"); > bpf_program__set_expected_attach_type(prog, BPF_TRACE_FENTRY); > bpf_program__set_attach_target(prog, xdp_fd, > "xdpfilt_blk_all"); > bpf_object__load(trace_obj) > > Signed-off-by: Eelco Chaudron > --- API-wise this looks good, thanks! Please address feedback below and re-submit once bpf-next opens. Can you please also convert one of existing selftests using open_opts's attach_prog_fd to use this API instead to have a demonstration there? > v1 -> v2: Remove requirement for attach type name in API > > tools/lib/bpf/libbpf.c | 33 +++++++++++++++++++++++++++++++-- > tools/lib/bpf/libbpf.h | 4 ++++ > tools/lib/bpf/libbpf.map | 1 + > 3 files changed, 36 insertions(+), 2 deletions(-) > > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c > index 514b1a524abb..9b8cab995580 100644 > --- a/tools/lib/bpf/libbpf.c > +++ b/tools/lib/bpf/libbpf.c > @@ -4939,8 +4939,8 @@ int bpf_program__load(struct bpf_program *prog, char *license, __u32 kern_ver) > { > int err = 0, fd, i, btf_id; > > - if (prog->type == BPF_PROG_TYPE_TRACING || > - prog->type == BPF_PROG_TYPE_EXT) { > + if ((prog->type == BPF_PROG_TYPE_TRACING || > + prog->type == BPF_PROG_TYPE_EXT) && !prog->attach_btf_id) { > btf_id = libbpf_find_attach_btf_id(prog); > if (btf_id <= 0) > return btf_id; > @@ -8132,6 +8132,35 @@ void bpf_program__bpil_offs_to_addr(struct bpf_prog_info_linear *info_linear) > } > } > > +int bpf_program__set_attach_target(struct bpf_program *prog, > + int attach_prog_fd, > + const char *attach_func_name) > +{ > + int btf_id; > + > + if (!prog || attach_prog_fd < 0 || !attach_func_name) > + return -EINVAL; > + > + if (attach_prog_fd) > + btf_id = libbpf_find_prog_btf_id(attach_func_name, > + attach_prog_fd); > + else > + btf_id = __find_vmlinux_btf_id(prog->obj->btf_vmlinux, > + attach_func_name, > + prog->expected_attach_type); > + > + if (btf_id <= 0) { > + if (!attach_prog_fd) > + pr_warn("%s is not found in vmlinux BTF\n", > + attach_func_name); libbpf_find_attach_btf_id's error reporting is misleading (it always reports as if error happened with vmlinux BTF, even if attach_prog_fd > 0). Could you please fix that and add better error reporting here for attach_prog_fd>0 case here? > + return btf_id; > + } > + > + prog->attach_btf_id = btf_id; > + prog->attach_prog_fd = attach_prog_fd; > + return 0; > +} > + > int parse_cpu_mask_str(const char *s, bool **mask, int *mask_sz) > { > int err = 0, n, len, start, end = -1; > diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h > index 3fe12c9d1f92..02fc58a21a7f 100644 > --- a/tools/lib/bpf/libbpf.h > +++ b/tools/lib/bpf/libbpf.h > @@ -334,6 +334,10 @@ LIBBPF_API void > bpf_program__set_expected_attach_type(struct bpf_program *prog, > enum bpf_attach_type type); > > +LIBBPF_API int > +bpf_program__set_attach_target(struct bpf_program *prog, int attach_prog_fd, > + const char *attach_func_name); > + > LIBBPF_API bool bpf_program__is_socket_filter(const struct bpf_program *prog); > LIBBPF_API bool bpf_program__is_tracepoint(const struct bpf_program *prog); > LIBBPF_API bool bpf_program__is_raw_tracepoint(const struct bpf_program *prog); > diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map > index b035122142bb..8aba5438a3f0 100644 > --- a/tools/lib/bpf/libbpf.map > +++ b/tools/lib/bpf/libbpf.map > @@ -230,6 +230,7 @@ LIBBPF_0.0.7 { > bpf_program__name; > bpf_program__is_extension; > bpf_program__is_struct_ops; > + bpf_program__set_attach_target; This will have to go into LIBBPF_0.0.8 once bpf-next opens. Please rebase and re-send then. > bpf_program__set_extension; > bpf_program__set_struct_ops; > btf__align_of; >