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=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 9E5A0C433DB for ; Mon, 11 Jan 2021 21:40:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 514F022B51 for ; Mon, 11 Jan 2021 21:40:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732515AbhAKVkS (ORCPT ); Mon, 11 Jan 2021 16:40:18 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45846 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725917AbhAKVkR (ORCPT ); Mon, 11 Jan 2021 16:40:17 -0500 Received: from mail-yb1-xb36.google.com (mail-yb1-xb36.google.com [IPv6:2607:f8b0:4864:20::b36]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 66880C061786; Mon, 11 Jan 2021 13:39:36 -0800 (PST) Received: by mail-yb1-xb36.google.com with SMTP id f13so177767ybk.11; Mon, 11 Jan 2021 13:39:36 -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=UCTLgQi//trDf/3xfHtidBpAiONSARa5x17fgpo7iHY=; b=eMYBooe4uyihN5ZgPxyecKyJftfnqFS3hDFX6FIsWaIsQQyWvPdQ/EkYOaSq2fkmxu kAjzHw/MI0ITcodiLKfOeDuCyXZO1BFLLKvQcjpc+sqt9OH5+1JMYnNI/0FSPYcWLYib EaaZ9LHVYzXKiWGKOISBMllG+UsPYpqeswEDwtUjtJiK6z6L4oG/0SE2PSXS32uTiC2Z QJscbLxYW6umwIegDm0sCX4JsAe9nx5XlepR3PSGAGRzojakRuKtgq+ES54DEhWmc96S GQkC27/jqsn4YK4IodFoVWc26eEBuIVKxSUfCO4qiuMThOMHd2+PZClUosp2oi3WcmI/ r9gA== 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=UCTLgQi//trDf/3xfHtidBpAiONSARa5x17fgpo7iHY=; b=PMJzDIBG413oL0htf/DTRqpeLqtVcjgXEvA6dryVu70n8zbgV4vxHi9C6x2EVZdMM7 HBV8aDj/G3pWs5ECEUWRI4VW7Aa6M99GnDx/3keWqwCjmbGw6I7JxaITBGAvubKdfvpY wlg9YG8d+0zq1sghiuVurDtGKBmNNBI/bSeG2SktfHvDOolekzChqCm9WXQwQFYwmg1v HvKx2JWiY4hFRX9/H63+SlKoFOoihM6lKSHkDaiAog1HU/V3/6lys/to023tH9YmoxQ5 d5MdZFBL3KbvEpGjuMgEx8I880l9CS+RlFnaIxAdJ1FQvWF0sGRJlV21I9J8gTMpNWcg 0eyQ== X-Gm-Message-State: AOAM532LIQy3rXiBwajVVJ6bpB+NeeV7cPHjl4w4+p7A4nTFzGSzm2G8 FCb8sFPVKOoEADgR1aySpEDOOLcnaIs/L7L0Qwk= X-Google-Smtp-Source: ABdhPJyMJPE5kdPqCRNVjjsxClKRWaYhRGXh80tUvdEi6eXnE4Dp00aw12MKmh0IqqQQOB9cebb92Buj0eyEKQD9LO8= X-Received: by 2002:a25:9882:: with SMTP id l2mr2375996ybo.425.1610401175718; Mon, 11 Jan 2021 13:39:35 -0800 (PST) MIME-Version: 1.0 References: <20210108220930.482456-1-andrii@kernel.org> <20210108220930.482456-7-andrii@kernel.org> In-Reply-To: From: Andrii Nakryiko Date: Mon, 11 Jan 2021 13:39:25 -0800 Message-ID: Subject: Re: [PATCH v2 bpf-next 6/7] libbpf: support kernel module ksym externs To: Hao Luo Cc: Andrii Nakryiko , bpf , Networking , Alexei Starovoitov , Daniel Borkmann , Kernel Team Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, Jan 11, 2021 at 11:00 AM Hao Luo wrote: > > Acked-by: Hao Luo , with a couple of nits. > > On Fri, Jan 8, 2021 at 2:09 PM Andrii Nakryiko wrote: > > > > Add support for searching for ksym externs not just in vmlinux BTF, but across > > all module BTFs, similarly to how it's done for CO-RE relocations. Kernels > > that expose module BTFs through sysfs are assumed to support new ldimm64 > > instruction extension with BTF FD provided in insn[1].imm field, so no extra > > feature detection is performed. > > > > Signed-off-by: Andrii Nakryiko > > --- > > tools/lib/bpf/libbpf.c | 47 +++++++++++++++++++++++++++--------------- > > 1 file changed, 30 insertions(+), 17 deletions(-) > > > > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c > > index 6ae748f6ea11..57559a71e4de 100644 > > --- a/tools/lib/bpf/libbpf.c > > +++ b/tools/lib/bpf/libbpf.c > [...] > > @@ -7319,7 +7321,8 @@ static int bpf_object__read_kallsyms_file(struct bpf_object *obj) > > static int bpf_object__resolve_ksyms_btf_id(struct bpf_object *obj) > > { > > struct extern_desc *ext; > > - int i, id; > > + struct btf *btf; > > + int i, j, id, btf_fd, err; > > > > for (i = 0; i < obj->nr_extern; i++) { > > const struct btf_type *targ_var, *targ_type; > > @@ -7331,8 +7334,22 @@ static int bpf_object__resolve_ksyms_btf_id(struct bpf_object *obj) > > if (ext->type != EXT_KSYM || !ext->ksym.type_id) > > continue; > > > > - id = btf__find_by_name_kind(obj->btf_vmlinux, ext->name, > > - BTF_KIND_VAR); > > + btf = obj->btf_vmlinux; > > + btf_fd = 0; > > + id = btf__find_by_name_kind(btf, ext->name, BTF_KIND_VAR); > > Is "if (id <= 0)" better? Just in case, more error code is introduced in future. There is id <= 0 right below after special-casing -ENOENT, so all works as you want, no? > > > + if (id == -ENOENT) { > > + err = load_module_btfs(obj); > > + if (err) > > + return err; > > + > > + for (j = 0; j < obj->btf_module_cnt; j++) { > > + btf = obj->btf_modules[j].btf; > > + btf_fd = obj->btf_modules[j].fd; > > + id = btf__find_by_name_kind(btf, ext->name, BTF_KIND_VAR); > > + if (id != -ENOENT) > > + break; > > + } > > + } > > if (id <= 0) { > > Nit: the warning message isn't accurate any more, right? We also > searched kernel modules' BTF. Right, how about just "failed to find BTF ID in kernel BTF"? Where "kernel BTF" is "vmlinux BTF or any of kernel modules' BTFs"? > > > pr_warn("extern (ksym) '%s': failed to find BTF ID in vmlinux BTF.\n", > > ext->name); > > @@ -7343,24 +7360,19 @@ static int bpf_object__resolve_ksyms_btf_id(struct bpf_object *obj) > [...] > > > -- > > 2.24.1 > >