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=-2.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 D2B9AC56202 for ; Wed, 18 Nov 2020 19:46:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 74613246A6 for ; Wed, 18 Nov 2020 19:46:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="UD2kY9Ja" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726098AbgKRTqQ (ORCPT ); Wed, 18 Nov 2020 14:46:16 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60058 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725710AbgKRTqQ (ORCPT ); Wed, 18 Nov 2020 14:46:16 -0500 Received: from mail-lj1-x231.google.com (mail-lj1-x231.google.com [IPv6:2a00:1450:4864:20::231]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 161ADC0613D4; Wed, 18 Nov 2020 11:46:16 -0800 (PST) Received: by mail-lj1-x231.google.com with SMTP id b17so3634655ljf.12; Wed, 18 Nov 2020 11:46:16 -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=KKZ4gb6lDjaHxR6iESt9TC7rWEjeXXRpmBGWuLjwqho=; b=UD2kY9Ja3dRw3CDr2g34AQQdxq9Id4kG+7UsWQFKu7Se6KpwNZmwIKzxkH0CBiN73E WzSYz4z6USEXQJJzSyuPeDj32w3IKuLLnTqREi1ObZD6euPYVUjtv4mBJaUdLJhZ50fZ rJnJtZBZGWvWI7t7R/a2VmG/fgbH9e5QYMysS5OzzLD9D517t6kW68NjdgSRjBrv81l8 ALaTrA7Y3XV0tBmKNR4rFTTW6Hfyg0Z+ghgJlOKUVNAAfjkJJgb5lffKZS9ta6tC/oIe cjcLJ5++yvAyjgsE0k/O/egJi0ygALZDUBdILGotcOg338c/r3vWqVekySTSuL606oa8 eiRA== 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=KKZ4gb6lDjaHxR6iESt9TC7rWEjeXXRpmBGWuLjwqho=; b=Gduq4ReqIfmHbkkmj1m3r4k0KrXvUA/+0HToYhQotllu1TYWLrq3zxfJJSXEDs4VlW O/+r0mpv+0RKEjdQpHyGj2L7o7XWflgf4w4BS2Tsrt1P1haHUQnl2GHktwNOkMFwN3bv vU60mRZkSc+Pwc4L/u3WbAMLVZorFxpLTfqKfNeNi6Chrzp+GyeQDmmypkemJkJ99iQq 1R/fsg3XrgicqdAOHwFhBPjL4pae8VYsCOUBTJ8JKA5JXASikv5A1JfkDDvQ5QhtdOtA wuza7eombRWwbBiFej00Avp0SVk3FnHgOcrVPIF9SPPuadG5Hthg7KhNw9vTBMKc8+BG F5Jw== X-Gm-Message-State: AOAM531kb/QSaQ7e4qflL8y8xF1Fe/Wb8eXiXMCeb79oexTrTdTnujni gVhLmTCupMaeYMN/excgGMzpbAFbstVpEDfFo7GDTbJReRY= X-Google-Smtp-Source: ABdhPJwzuPmS1cgjgZVNL6pP4CI/HcN9peF/Y7NTvyncavVMzXu/u/1FNFCypGB6OXXldxaxhG+zlLvnZVpBNqBTEbQ= X-Received: by 2002:a2e:86c5:: with SMTP id n5mr4627251ljj.450.1605728774563; Wed, 18 Nov 2020 11:46:14 -0800 (PST) MIME-Version: 1.0 References: <20201116175107.02db396d@gandalf.local.home> <47463878.48157.1605640510560.JavaMail.zimbra@efficios.com> <20201117142145.43194f1a@gandalf.local.home> <375636043.48251.1605642440621.JavaMail.zimbra@efficios.com> <20201117153451.3015c5c9@gandalf.local.home> <20201118132136.GJ3121378@hirez.programming.kicks-ass.net> <87h7pmwyta.fsf@mid.deneb.enyo.de> <20201118092228.4f6e5930@gandalf.local.home> In-Reply-To: <20201118092228.4f6e5930@gandalf.local.home> From: Alexei Starovoitov Date: Wed, 18 Nov 2020 11:46:02 -0800 Message-ID: Subject: Re: violating function pointer signature To: Steven Rostedt Cc: Florian Weimer , Peter Zijlstra , Mathieu Desnoyers , linux-kernel , Matt Mullins , Ingo Molnar , Alexei Starovoitov , Daniel Borkmann , Dmitry Vyukov , Martin KaFai Lau , Song Liu , Yonghong Song , Andrii Nakryiko , John Fastabend , KP Singh , netdev , bpf , Kees Cook , Josh Poimboeuf , linux-toolchains@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Wed, Nov 18, 2020 at 6:22 AM Steven Rostedt wrote: > > Thus, all functions will be non-variadic in these cases. That's not the only case where it will blow up. Try this on sparc: struct foo { int a; }; struct foo foo_struct(void) { struct foo f = {}; return f; } int foo_int(void) { return 0; } or this link: https://godbolt.org/z/EdM47b Notice: jmp %i7+12 The function that returns small struct will jump to a different instruction in the caller. I think none of the tracepoints return structs and void foo(void) is fine on x86. Just pointing out that it's more than just variadic.