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, URIBL_BLOCKED,USER_IN_DEF_DKIM_WL 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 0195EC433DB for ; Tue, 9 Feb 2021 15:07:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BBE5264EB8 for ; Tue, 9 Feb 2021 15:07:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232134AbhBIPHF (ORCPT ); Tue, 9 Feb 2021 10:07:05 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49494 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232047AbhBIPG7 (ORCPT ); Tue, 9 Feb 2021 10:06:59 -0500 Received: from mail-vs1-xe2d.google.com (mail-vs1-xe2d.google.com [IPv6:2607:f8b0:4864:20::e2d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2933FC061786 for ; Tue, 9 Feb 2021 07:06:18 -0800 (PST) Received: by mail-vs1-xe2d.google.com with SMTP id o186so9576666vso.1 for ; Tue, 09 Feb 2021 07:06:18 -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=DbTXuOBblU9jPQgm8MRCYvaknfLBOXYdW6zn/C5UsN4=; b=g/Bp8tCC+w+JRa9cSdlGPUAvUtCoqGkBlEfY1+vOAFxvIGs7DjlKloprbuxuxF5h9u Gef1X9bSr41acjjYqEEn/POZS54oqzEyIGXl5EbHqEjBZguUxuFRzcCO5egLwpSxCoMc dk1WYzkGF0G3b6dc2FVDPpzbwxilHHlDVDoL/kLgmswz2m0pUz4Pvcx3Ktb83zxvw4OZ 2KnAQSskFdQbV+G/GjXouzw9Ls/cP5stTdUfuxLEfTiIxHj9CE/0C3n8kGuBGxmBSk+S H0jd7NON01AGegEToSoLwVq1BJS84nIx5elUDZDWnMiy550CFlQrmjzYotNYVHeZ05aG xP4w== 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=DbTXuOBblU9jPQgm8MRCYvaknfLBOXYdW6zn/C5UsN4=; b=AArbdvTEiR3K0oJ3gyOwshZecoRDEHttSofK2XIPplJ5x6SIaghrBCJzM/2pKqmYZd F+IO/CV/xbLS2KwCpO4X7dlxJUXw3yXmSYAvfsruU1/nnokxxer6W7tBu4vrSckr2Wxn 1tubHT9KOxBJdpzsnxbILR0xPnGrwvoQF/yI8ft6mbYDNvM2Od4sziZaZU4gsJuCmVmw A3b0zAfUOnyyyApxyXeHJXmYuyreeAU2KMr+lWxATN+5+83IKFw4HxzEPUG3zQu5KMxK wX827hJD7qeQFTCSA575Rm1cEs4AuNCz7TkbmZ5ApvjzkJ0eZMh/AcL6aumLlHnzPI3R kPmg== X-Gm-Message-State: AOAM530wNmrLFC1nwYGo162NOtn9PcGiRgW+lf5vaO+eAK0QK616y+T1 SeThfo6+E2OgNMEwwrCbTaNATmUuB6AGJ0l8OGJcSUzNAI4= X-Google-Smtp-Source: ABdhPJxhv1/QRVdi6XCilq9+IFSXqAjlels0Dy9hn4GDFSmN3+hX4k6pNhxQyVDMM4aboLB11aWrWNo+3Q4Gk5bskyQ= X-Received: by 2002:a67:1142:: with SMTP id 63mr13478014vsr.24.1612883176546; Tue, 09 Feb 2021 07:06:16 -0800 (PST) MIME-Version: 1.0 References: <20210201172530.1141087-1-gprocida@google.com> <20210205134221.2953163-1-gprocida@google.com> <20210205134221.2953163-6-gprocida@google.com> In-Reply-To: From: Giuliano Procida Date: Tue, 9 Feb 2021 15:05:42 +0000 Message-ID: Subject: Re: [PATCH dwarves v3 5/5] btf_encoder: Align .BTF section to 8 bytes To: Andrii Nakryiko Cc: dwarves@vger.kernel.org, Arnaldo Carvalho de Melo , Andrii Nakryiko , Alexei Starovoitov , =?UTF-8?Q?Matthias_M=C3=A4nnich?= , kernel-team@android.com, Kernel Team , bpf Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: dwarves@vger.kernel.org On Mon, 8 Feb 2021 at 22:30, Andrii Nakryiko wrote: > > On Fri, Feb 5, 2021 at 5:42 AM Giuliano Procida wrote: > > > > This is to avoid misaligned access to BTF type structs when > > memory-mapping ELF objects. > > > > Signed-off-by: Giuliano Procida > > --- > > I trust you did verify that it actually works in cases where > previously .BTF was mis-aligned? > Yes. :-) > Acked-by: Andrii Nakryiko > > > libbtf.c | 9 +++++++++ > > 1 file changed, 9 insertions(+) > > > > diff --git a/libbtf.c b/libbtf.c > > index 9f4abb3..6754a17 100644 > > --- a/libbtf.c > > +++ b/libbtf.c > > @@ -744,6 +744,14 @@ static int btf_elf__write(const char *filename, struct btf *btf) > > goto out; > > } > > > > + /* > > + * We'll align .BTF to 8 bytes to cater for all architectures. It'd be > > + * nice if we could fetch this value from somewhere. The BTF > > + * specification does not discuss alignment and its trailing string > > + * table is not currently padded to any particular alignment. > > + */ > > + const size_t btf_alignment = 8; > > + > > /* > > * First we check if there is already a .BTF section present. > > */ > > @@ -821,6 +829,7 @@ static int btf_elf__write(const char *filename, struct btf *btf) > > elf_error("elf_getshdr(btf_scn) failed"); > > goto out; > > } > > + btf_shdr.sh_addralign = btf_alignment; > > btf_shdr.sh_entsize = 0; > > btf_shdr.sh_flags = 0; > > if (dot_btf_offset) > > -- > > 2.30.0.478.g8a0d178c01-goog > > > > -- > To unsubscribe from this group and stop receiving emails from it, send an email to kernel-team+unsubscribe@android.com. >