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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 29509C433F5 for ; Tue, 18 Jan 2022 23:01:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350131AbiARXB2 (ORCPT ); Tue, 18 Jan 2022 18:01:28 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:51880 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350114AbiARXB1 (ORCPT ); Tue, 18 Jan 2022 18:01:27 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1642546886; 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=imSbjfG3HpJVgHUztBteAKnTWeE4AQAds5w4lniIVaU=; b=glt8S3+sl5nQWqEhmmUxb6hzFrTqIFeA28MfjXx+uP9QBDEOUon8Kr5P4I5WwfA/2Y61dq vxRS9t/XJ0O8tYI0dSXHbAFLZgzCwkOz9qBTsrWSTX5UkQbg/urQKisQYkyDtH+SYPoVko cSA77K4RuZG0iDFB1hF9pDpaqzbuqsY= Received: from mail-qv1-f70.google.com (mail-qv1-f70.google.com [209.85.219.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-537-QKyUdb-2O--SdT2IrYuqHA-1; Tue, 18 Jan 2022 18:01:25 -0500 X-MC-Unique: QKyUdb-2O--SdT2IrYuqHA-1 Received: by mail-qv1-f70.google.com with SMTP id jn6-20020ad45de6000000b004146a2f1f97so681940qvb.19 for ; Tue, 18 Jan 2022 15:01:25 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=imSbjfG3HpJVgHUztBteAKnTWeE4AQAds5w4lniIVaU=; b=208dvGpt2ipSSf87egBePe7VCvqCaQvG+025YZ1S2WUZLcXjhWDmNVKQKYAtGxWwet MKQAsZ941ij5d1azEjKQH2rTusm3O2FZHGPQfRPZbMiiZoM35Vqm3OtxeM0jT6e+JjxI orFrdbn/PF98ry1nrFXKMSsnj4Kodn+nCc2D6w0n5xZFRntXF3fNayYuFI6MQTW+4/AI BXF/qVU3a6wwWYb8bdZjn54wJMA2PKvzW1InfBVA2DJVdeMHo6BF5+rv2ZIsUKcCJGTn 7m3JWHkr96F7xr25QF/q3Rqg7J+iXN+wOWO2b2odp34Ud6GzDLDJYjmrTwIjvc6ebCwh mgKQ== X-Gm-Message-State: AOAM533dpll1i8Gltnufvw/If+5m4+2MGBTksssViw2SCMtaKhnvQaY2 /NM7KakUE35/f8NhK3wZbClkpMabMnuIgN+dmsx+okCShTnZU6JiXQLLuVFSPY9v6XUh5TyBzoW yJiqpFzPBQQ8rEmPY24KOW6XS X-Received: by 2002:ac8:57d6:: with SMTP id w22mr9729198qta.167.1642546884605; Tue, 18 Jan 2022 15:01:24 -0800 (PST) X-Google-Smtp-Source: ABdhPJxyQ926lYNQFaaESs3XDeB0TGuTp5YmiFt/PM6FFwVllm13rgEx76LTNmglnZnmxg9ERdqTBA== X-Received: by 2002:ac8:57d6:: with SMTP id w22mr9729170qta.167.1642546884378; Tue, 18 Jan 2022 15:01:24 -0800 (PST) Received: from treble ([2600:1700:6e32:6c00::c]) by smtp.gmail.com with ESMTPSA id i5sm4598139qkn.19.2022.01.18.15.01.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 18 Jan 2022 15:01:23 -0800 (PST) Date: Tue, 18 Jan 2022 15:01:20 -0800 From: Josh Poimboeuf To: Borislav Petkov Cc: Nick Desaulniers , Vasily Gorbik , Linus Torvalds , Ingo Molnar , Dave Hansen , Thomas Gleixner , Peter Zijlstra , Luc Van Oostenryck , x86@kernel.org, llvm@lists.linux.dev, linux-sparse@vger.kernel.org, linux-kernel@vger.kernel.org, kernel test robot , Nathan Chancellor Subject: Re: [PATCH] objtool: prefer memory clobber & %= to volatile & __COUNTER__ Message-ID: <20220118230120.pivvson7qekfiqic@treble> References: <20220114010526.1776605-1-ndesaulniers@google.com> <20220118192256.jzk5dnceeusq7x7u@treble> MIME-Version: 1.0 In-Reply-To: <20220118192256.jzk5dnceeusq7x7u@treble> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=jpoimboe@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Precedence: bulk List-ID: X-Mailing-List: linux-sparse@vger.kernel.org On Tue, Jan 18, 2022 at 11:22:59AM -0800, Josh Poimboeuf wrote: > On Sun, Jan 16, 2022 at 02:32:59PM +0100, Borislav Petkov wrote: > > so I like the local label and how it is more readable this way. > > > > So, provided the memory clobber works (I wonder here if Josh has some > > concrete failing cases which could be tested with your version) and > > after the nitpicks have been addressed > > > > Acked-by: Borislav Petkov > > I think Nick was already able to recreate the original issue. I'll run > it through some more testing. > > I wanted to make this change years ago, but couldn't because of legacy > toolchains. Here's hoping this is the final solution for those @#$%^ > macros. > > Boris, thanks for looping Nick in, I should have done so to begin with. Apparently this patch isn't going to work after all :-( https://lkml.kernel.org/r/202201190632.lhlaiCBk-lkp@intel.com With the two WARN_ONs in media_request_object_complete(), GCC apparently considers the two reachable() asm statements as duplicates, and it removes the second one. -- Josh