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=-15.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 D7C19C433E6 for ; Wed, 20 Jan 2021 12:53:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9B51523355 for ; Wed, 20 Jan 2021 12:53:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731803AbhATMwd (ORCPT ); Wed, 20 Jan 2021 07:52:33 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:38098 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733288AbhATM2b (ORCPT ); Wed, 20 Jan 2021 07:28:31 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1611145623; 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: in-reply-to:in-reply-to:references:references; bh=RVtx5OM9lrNbMwajYs+XPwUc9ia/t8QLsSQbiLfcync=; b=Byi/47FITHQJHVutreZyzhpzjq72MrPubk4tDeOATKh4tmpWx6MSvwTTMZrqD3hFyPa4HZ NYsEvaW/cqx3vB3gX/gNkLAcy2m/blVbv5NKWoGXxbfbyQzOLyx51EZBO70TVXoBDwBatv xUSmoh+8GeYz5GztSkyUoDeAMSx2TuQ= 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-216-sHXGSNbeM1yDDOqFGH6ofQ-1; Wed, 20 Jan 2021 07:26:59 -0500 X-MC-Unique: sHXGSNbeM1yDDOqFGH6ofQ-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 1D2D8180A093; Wed, 20 Jan 2021 12:26:57 +0000 (UTC) Received: from krava (unknown [10.40.194.35]) by smtp.corp.redhat.com (Postfix) with SMTP id 15411614FF; Wed, 20 Jan 2021 12:26:46 +0000 (UTC) Date: Wed, 20 Jan 2021 13:26:46 +0100 From: Jiri Olsa To: Andrii Nakryiko Cc: Jiri Olsa , Arnaldo Carvalho de Melo , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , dwarves@vger.kernel.org, Networking , bpf , Yonghong Song , Hao Luo , Martin KaFai Lau , Song Liu , John Fastabend , KP Singh , Joe Lawrence , Mark Wielaard Subject: Re: [PATCH bpf-next 3/3] libbpf: Use string table index from index table if needed Message-ID: <20210120122646.GC1760208@krava> References: <20210119221220.1745061-1-jolsa@kernel.org> <20210119221220.1745061-4-jolsa@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, Jan 19, 2021 at 05:22:08PM -0800, Andrii Nakryiko wrote: > On Tue, Jan 19, 2021 at 2:15 PM Jiri Olsa wrote: > > > > For very large ELF objects (with many sections), we could > > get special value SHN_XINDEX (65535) for elf object's string > > table index - e_shstrndx. > > > > In such case we need to call elf_getshdrstrndx to get the > > proper string table index. > > > > Signed-off-by: Jiri Olsa > > --- > > tools/lib/bpf/btf.c | 14 ++++++++++++-- > > 1 file changed, 12 insertions(+), 2 deletions(-) > > > > diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c > > index 3c3f2bc6c652..4fe987846bc0 100644 > > --- a/tools/lib/bpf/btf.c > > +++ b/tools/lib/bpf/btf.c > > @@ -863,6 +863,7 @@ static struct btf *btf_parse_elf(const char *path, struct btf *base_btf, > > Elf_Scn *scn = NULL; > > Elf *elf = NULL; > > GElf_Ehdr ehdr; > > + size_t shstrndx; > > > > if (elf_version(EV_CURRENT) == EV_NONE) { > > pr_warn("failed to init libelf for %s\n", path); > > @@ -887,7 +888,16 @@ static struct btf *btf_parse_elf(const char *path, struct btf *base_btf, > > pr_warn("failed to get EHDR from %s\n", path); > > goto done; > > } > > - if (!elf_rawdata(elf_getscn(elf, ehdr.e_shstrndx), NULL)) { > > + > > + /* > > + * Get string table index from extended section index > > + * table if needed. > > + */ > > + shstrndx = ehdr.e_shstrndx; > > + if (shstrndx == SHN_XINDEX && elf_getshdrstrndx(elf, &shstrndx)) > > + goto done; > > just use elf_getshdrstrndx() unconditionally, it works for extended > and non-extended numbering (see libbpf.c). I did not see that, ok thanks, jirka > > > + > > + if (!elf_rawdata(elf_getscn(elf, shstrndx), NULL)) { > > pr_warn("failed to get e_shstrndx from %s\n", path); > > goto done; > > } > > @@ -902,7 +912,7 @@ static struct btf *btf_parse_elf(const char *path, struct btf *base_btf, > > idx, path); > > goto done; > > } > > - name = elf_strptr(elf, ehdr.e_shstrndx, sh.sh_name); > > + name = elf_strptr(elf, shstrndx, sh.sh_name); > > if (!name) { > > pr_warn("failed to get section(%d) name from %s\n", > > idx, path); > > -- > > 2.27.0 > > >