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=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 DF189C2BA83 for ; Fri, 14 Feb 2020 07:34:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AB06722314 for ; Fri, 14 Feb 2020 07:34:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="e8Eny1Ef" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728844AbgBNHel (ORCPT ); Fri, 14 Feb 2020 02:34:41 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:44591 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728829AbgBNHel (ORCPT ); Fri, 14 Feb 2020 02:34:41 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1581665679; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=1vTB07YCHquUQRM8bojAgZpjMe0UTX9SMv5SiNm5LOI=; b=e8Eny1EfidtErfpAFV0MQmyCoOPlzf0MH+TbYpUjqDZV9S4t/oxqi33F/DMPswRYJMlra9 V9gQgdqfSy1Q3ifjxEE7xFImtxN8iOSuRh8SLQhvR8inp8xmI7lsSQoU+1z3g63sJrnN6Y YTh7exEj+eXD1u/P1iUtinP8pXAGJDE= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-311-gFvEo78qM1yO2J4hbv0WnQ-1; Fri, 14 Feb 2020 02:34:38 -0500 X-MC-Unique: gFvEo78qM1yO2J4hbv0WnQ-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 2CE7D18B9F80; Fri, 14 Feb 2020 07:34:36 +0000 (UTC) Received: from [10.36.116.117] (ovpn-116-117.ams2.redhat.com [10.36.116.117]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 2D6865DA87; Fri, 14 Feb 2020 07:34:31 +0000 (UTC) From: "Eelco Chaudron" To: "Andrii Nakryiko" Cc: bpf , "David S. Miller" , Networking , "Alexei Starovoitov" , "Daniel Borkmann" , "Martin Lau" , "Song Liu" , "Yonghong Song" , "Andrii Nakryiko" , "Toke =?utf-8?b?SMO4aWxhbmQtSsO4cmdlbnNlbg==?=" Subject: Re: [PATCH bpf-next v2] libbpf: Add support for dynamic program attach target Date: Fri, 14 Feb 2020 08:34:28 +0100 Message-ID: In-Reply-To: References: <158160616195.80320.5636088335810242866.stgit@xdp-tutorial> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8"; format=flowed X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Content-Transfer-Encoding: quoted-printable Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On 13 Feb 2020, at 18:42, Andrii Nakryiko wrote: > On Thu, Feb 13, 2020 at 7:05 AM Eelco Chaudron =20 > 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 =3D bpf_prog_get_fd_by_id(id); >> trace_obj =3D bpf_object__open_file("func.o", NULL); >> prog =3D 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? Yes will update the one I added for bfp2bpf testing=E2=80=A6 >> 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,=20 >> char *license, __u32 kern_ver) >> { >> int err =3D 0, fd, i, btf_id; >> >> - if (prog->type =3D=3D BPF_PROG_TYPE_TRACING || >> - prog->type =3D=3D BPF_PROG_TYPE_EXT) { >> + if ((prog->type =3D=3D BPF_PROG_TYPE_TRACING || >> + prog->type =3D=3D BPF_PROG_TYPE_EXT) &&=20 >> !prog->attach_btf_id) { >> btf_id =3D libbpf_find_attach_btf_id(prog); >> if (btf_id <=3D 0) >> return btf_id; >> @@ -8132,6 +8132,35 @@ void bpf_program__bpil_offs_to_addr(struct=20 >> 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 =3D libbpf_find_prog_btf_id(attach_func_name, >> + attach_prog_fd); >> + else >> + btf_id =3D=20 >> __find_vmlinux_btf_id(prog->obj->btf_vmlinux, >> + attach_func_name, >> + =20 >> prog->expected_attach_type); >> + >> + if (btf_id <=3D 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? > I did not add log messages for the btf_id > 0 case as they are covered=20 in the libbpf_find_prog_btf_id() function. Please let me know if this is=20 not enough. >> + return btf_id; >> + } >> + >> + prog->attach_btf_id =3D btf_id; >> + prog->attach_prog_fd =3D attach_prog_fd; >> + return 0; >> +} >> + >> int parse_cpu_mask_str(const char *s, bool **mask, int *mask_sz) >> { >> int err =3D 0, n, len, start, end =3D -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=20 >> attach_prog_fd, >> + const char *attach_func_name); >> + >> LIBBPF_API bool bpf_program__is_socket_filter(const struct=20 >> bpf_program *prog); >> LIBBPF_API bool bpf_program__is_tracepoint(const struct bpf_program=20 >> *prog); >> LIBBPF_API bool bpf_program__is_raw_tracepoint(const struct=20 >> 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. Will do=E2=80=A6 >> bpf_program__set_extension; >> bpf_program__set_struct_ops; >> btf__align_of; >>