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=-1.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 3A0B3C433E0 for ; Wed, 1 Jul 2020 16:36:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 135F720781 for ; Wed, 1 Jul 2020 16:36:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="V58Y5n//" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732231AbgGAQgy (ORCPT ); Wed, 1 Jul 2020 12:36:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42578 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731394AbgGAQgy (ORCPT ); Wed, 1 Jul 2020 12:36:54 -0400 Received: from mail-pj1-x1042.google.com (mail-pj1-x1042.google.com [IPv6:2607:f8b0:4864:20::1042]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F2397C08C5C1; Wed, 1 Jul 2020 09:36:53 -0700 (PDT) Received: by mail-pj1-x1042.google.com with SMTP id b92so11264611pjc.4; Wed, 01 Jul 2020 09:36:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=GgioNzSta8sSjK2l1P/5dr6v68UV138xyv8W1eB/1gY=; b=V58Y5n//HCW652zIm/606vN7NhzBHLyRDKhGIc/xUqQezqiMAawldBH7AbpsuNbD7L ieU3j0zkzxEKToD+T8zCXhgulCOB/M0Pma6lbBBBnUgcVTSz1Mv92Z/DvbRRicm3aOaT n6B1AtyclpiP/ZjsppnLteXfFNqA9uwK8+VgAfubP6zaU2sZxxwtXRSnLnfegE3e5aBS 0nSpYYxh+Fq+ayrLiGOgPG9AM7MJeZ80vovNLjuwNCX6W+Bnku1CV2n0o2mu5vKLl527 Vbe6HCxKSIh1Q8tfjBMTd5fXJHdwmsMmmoeU6NlyRyX48LRNf2UGRI78g0r7xaFvg2MX /Ngg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=GgioNzSta8sSjK2l1P/5dr6v68UV138xyv8W1eB/1gY=; b=dqScTTL7HyPigq9pNdPpz1IADP5aOCQjKJ2AnpMeT6lnT6goda5Ee0SrgiR/3J7EOo PJ8AprYt54Wk4H2ztHpig/twNWIgMhiGsZD1r0RtWLobzkZn1wjwpbTU4Pr54gQYe2ey wcJbQH7yhmgEIfwRCw7buRpQokxZsXGqlXXKL8wIumyLF7IVN4E7pzbHk4ADA6CIw+ES dj8FHDk0nl6T3ePR4OAEbXBXjxlq29MreAKvygmkp7AIK1sZ2abhM/s+WwlbTQfgLSWv 7jTH5E/NRi6phmLf2pD6tyWXpRv9dLgMP7Fg9l0JgAn9nOOj5KA6Ta6Bg6B0i7thgO5c gFFQ== X-Gm-Message-State: AOAM532vgZF7D5Wx+HE4TK3ncu2Lt1Kp/XNKjhx0dZHQykAPeE+vlkA2 nU7VPYJa9Ba9x3EwdWCc80I= X-Google-Smtp-Source: ABdhPJy+3zrMbkxQP0lAB9c1Mv2U7SWy+vkKt0J4REeA/Z+IDhJFrMwnA4UP8i6s+3ZYUdIV8sejyg== X-Received: by 2002:a17:90a:1b42:: with SMTP id q60mr5761677pjq.78.1593621413431; Wed, 01 Jul 2020 09:36:53 -0700 (PDT) Received: from ast-mbp.dhcp.thefacebook.com ([2620:10d:c090:400::5:7882]) by smtp.gmail.com with ESMTPSA id y12sm6357791pfm.158.2020.07.01.09.36.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 01 Jul 2020 09:36:52 -0700 (PDT) Date: Wed, 1 Jul 2020 09:36:50 -0700 From: Alexei Starovoitov To: Andrii Nakryiko Cc: Andrii Nakryiko , bpf , Network Development , Alexei Starovoitov , Daniel Borkmann , Kernel Team , Anton Protopopov Subject: Re: [PATCH bpf-next 0/3] Strip away modifiers from BPF skeleton global variables Message-ID: <20200701163650.qoxr5xgjmz5mpzgn@ast-mbp.dhcp.thefacebook.com> References: <20200701064527.3158178-1-andriin@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Wed, Jul 01, 2020 at 09:08:45AM -0700, Andrii Nakryiko wrote: > On Wed, Jul 1, 2020 at 8:02 AM Alexei Starovoitov > wrote: > > > > On Tue, Jun 30, 2020 at 11:46 PM Andrii Nakryiko wrote: > > > > > > Fix bpftool logic of stripping away const/volatile modifiers for all global > > > variables during BPF skeleton generation. See patch #1 for details on when > > > existing logic breaks and why it's important. Support special .strip_mods=true > > > mode in btf_dump. Add selftests validating that everything works as expected. > > > > Why bother with the flag? > > You mean btf_dump should do this always? That's a bit too invasive a > change, I don't like it. > > > It looks like bugfix to me. > > It can be considered a bug fix for bpftool's skeleton generation, but > it depends on non-trivial changes in libbpf, which are not bug fix per > se, so should probably better go through bpf-next. I'm not following. Without tweaking opts and introducing new flag the actual fix is only two hunks in patch 1: @@ -1045,6 +1050,10 @@ static void btf_dump_emit_type_decl(struct btf_dump *d, __u32 id, stack_start = d->decl_stack_cnt; for (;;) { + t = btf__type_by_id(d->btf, id); + if (btf_is_mod(t)) + goto skip_mod; + err = btf_dump_push_decl_stack_id(d, id); if (err < 0) { /* @@ -1056,12 +1065,11 @@ static void btf_dump_emit_type_decl(struct btf_dump *d, __u32 id, d->decl_stack_cnt = stack_start; return; } - +skip_mod: /* VOID */ if (id == 0) break; - t = btf__type_by_id(d->btf, id);