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 CA5DEC3B1B2 for ; Fri, 14 Feb 2020 17:54:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9AC4320848 for ; Fri, 14 Feb 2020 17:54:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Eyayccx+" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388261AbgBNRyD (ORCPT ); Fri, 14 Feb 2020 12:54:03 -0500 Received: from mail-qk1-f194.google.com ([209.85.222.194]:38448 "EHLO mail-qk1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388618AbgBNRyC (ORCPT ); Fri, 14 Feb 2020 12:54:02 -0500 Received: by mail-qk1-f194.google.com with SMTP id z19so10014826qkj.5; Fri, 14 Feb 2020 09:54:01 -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:content-transfer-encoding; bh=WvhILt6tPP0OHZxfssLr4mmrk5pWCDDsreMb5sB47qY=; b=Eyayccx+zpI5bL9Frh1yHdrZJVcFjRIXP0Y0bH4ogC+QDO/eTm50hcbEg4swRS9Civ wiZ4KpRP+/lR1qA4RC8ehof2MYPsNHNHGeNYdK59Z1UQQa5H2v4HviD3bEziXo7TbVhT lcK6P4YwBylg2oYzMkEbP9u6bD8KjB3zUxgAbT648CPSUlQtkhpilUhsGiQrYeS9kRf2 D8c38YLzx3HzjVIo07j4ffa8WCfHkJokBEPasltmJiT2zFMvF9KcwFajVe1zGD+TG4yu PArXeVsgJfFrWdjhkE2miN7gQ+Rg+kSotCkW4tR+YVp/TBCiD8/xP+TNK9nvj9hvHB9c P8hQ== 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:content-transfer-encoding; bh=WvhILt6tPP0OHZxfssLr4mmrk5pWCDDsreMb5sB47qY=; b=XIr+zxIzHS6LOpAoSLy1BbzDctiJViY2Sz3MJ/xhyBeBnQs2ZDqQb/K27d2JBi9/UH 8xt9QMMO1Fiu3ltt5oYLV1moWNvIcVT0aLM8MWCo97YbgIB08gqpBa+/lG7tqe1sP8cb N1qTtDlmF04CfjnVtyVbgb8VITpXok4NPSUSA+Bj2XcI+H4CVUCo2rw6C1nQLeVgWOsX eguwrBP/kjB4eUj7KrMsJbq+YuRyVhpCeYbtQ8o4Cm9gskAs69SwDpV2FyOaEoUL8ukS tHzvIvm658+5KivsLznlfnaqRdqVvUnUhF85f0TCS4e+CZ7ijwlXBuXuugsew1nXz5Mm ItvQ== X-Gm-Message-State: APjAAAXFlY6DC89QXABiGmAGI1BbdD8RCsCbENm+4/roNFB3QdMKW/Tc vHcj02R8ippQmZHGROvXqRJiPnJwQPJ9TmOEz0I= X-Google-Smtp-Source: APXvYqzChKM6+5lq4rI8BD0xaZHNjRCCBF0bQsBaYoIj+aKqYbgMQdMUlt2TezVAcgNTvCA3Sfrb2bxha5o8Jj1LnmA= X-Received: by 2002:a37:2744:: with SMTP id n65mr3715809qkn.92.1581702841141; Fri, 14 Feb 2020 09:54:01 -0800 (PST) MIME-Version: 1.0 References: <158160616195.80320.5636088335810242866.stgit@xdp-tutorial> In-Reply-To: From: Andrii Nakryiko Date: Fri, 14 Feb 2020 09:53:50 -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" Content-Transfer-Encoding: quoted-printable Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Thu, Feb 13, 2020 at 11:34 PM Eelco Chaudron wrote= : > > > > On 13 Feb 2020, at 18:42, Andrii Nakryiko wrote: > > > 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 =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, > >> 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) && > >> !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 > >> 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 > >> __find_vmlinux_btf_id(prog->obj->btf_vmlinux, > >> + attach_func_name, > >> + > >> 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 > in the libbpf_find_prog_btf_id() function. Please let me know if this is > not enough. I see... libbpf_find_attach_btf_id is still wrong, so maybe let's move this warning into __find_vmlinux_btf_id for more symmetrical (with libbpf_find_prog_btf_id) error reporting? > > >> + 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 > >> 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. > > Will do=E2=80=A6 > > >> bpf_program__set_extension; > >> bpf_program__set_struct_ops; > >> btf__align_of; > >> >