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=-23.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_IN_DEF_DKIM_WL 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 21E25C433E0 for ; Mon, 11 Jan 2021 19:01:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CFA0B22A84 for ; Mon, 11 Jan 2021 19:01:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390442AbhAKTBe (ORCPT ); Mon, 11 Jan 2021 14:01:34 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39816 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731583AbhAKTBd (ORCPT ); Mon, 11 Jan 2021 14:01:33 -0500 Received: from mail-ej1-x633.google.com (mail-ej1-x633.google.com [IPv6:2a00:1450:4864:20::633]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ADF69C061795 for ; Mon, 11 Jan 2021 11:00:52 -0800 (PST) Received: by mail-ej1-x633.google.com with SMTP id g20so1225198ejb.1 for ; Mon, 11 Jan 2021 11:00:52 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=UAQtzSxGA3+ZigKcaBoyf+oVRyAJV6LvZeoMkFVxqCo=; b=ADxSEU2Xcs7JJQ7HYsB23h3NP6nhLjLwH5UPPSxABsaoHdE/LVWZF+cSickls4ki5I kxE+Kbg42jdxc845ALuahXAteS24KN+GJN0VwpF3oLFAUdrcK9ZOKr4dmtzhQcgTs7tj TXOMfhebzWE1PbsUZINxhW5NePEMVBGYPmQhPWAahb+xfmeJaA6nMccl+kI9FemrjGQA pfD1jOkLdRwBjaEQnHhU4laTI84irMJw2WeKIPptHge5Qo3B+u+zhliUM0tNdIcQwEqm mU3kkSCmjpZxtQS3QgoHE/brKhgB4Ernuz7efZbYNohSlDuGVxXOqHmZBK0YkBuYZ5l4 1Sow== 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=UAQtzSxGA3+ZigKcaBoyf+oVRyAJV6LvZeoMkFVxqCo=; b=ZKccLIimkLlKUn49Icq0jVOwWy++saLonJjSPtOL9vrnbWsFHvE4ml+LI2aRhqTs9O UI5oTUhs2HjTaWoyNNoCVn3LW1oGeRXIPRuLm/N34DZJ+nuZPILFd9ryJgX4FME1Jb5c mg43Z8HGjg+1Nt7O1HUXNRg1C/QF/Qv3FObcSx0IN7X25l+TZpcjVSReCkTWgG2fj2NG pMYNG5vGVP2T7UIF4cEI95gbsW/lJFqp8GhnnJ9EcY6g1hPOsDQvQIGLlhlDei75slF1 hvzPoGbKDuHHb1Zh1PCo2q9oqIcnE8a9EUjBsPNg9PrCfS1j3fxP4j/65//u1ZZcj7qz bQbQ== X-Gm-Message-State: AOAM533QoYWwZ0LrL3nh/Inoj4Ng8Boa2zQ5HxYzmJs1SjPvJAfiYTFX jCVH4mRxn7oNyV4R+O4fkAHr/biAoPYs7OR7Z+sfBg== X-Google-Smtp-Source: ABdhPJxhQG5TtXErzAksyOUEhDTT+CD5yPBqo+gUtvm3FIrn5yRPBTHtRuPLP/1K5hall3gLZPgS1P+qdLG/+FanLIA= X-Received: by 2002:a17:906:eb49:: with SMTP id mc9mr565992ejb.487.1610391651162; Mon, 11 Jan 2021 11:00:51 -0800 (PST) MIME-Version: 1.0 References: <20210108220930.482456-1-andrii@kernel.org> <20210108220930.482456-7-andrii@kernel.org> In-Reply-To: <20210108220930.482456-7-andrii@kernel.org> From: Hao Luo Date: Mon, 11 Jan 2021 11:00:39 -0800 Message-ID: Subject: Re: [PATCH v2 bpf-next 6/7] libbpf: support kernel module ksym externs To: Andrii Nakryiko Cc: 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 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. > + 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. > 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 >