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 DEFE1C433F5 for ; Mon, 31 Jan 2022 20:46:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1379266AbiAaUpz (ORCPT ); Mon, 31 Jan 2022 15:45:55 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39172 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350866AbiAaUpe (ORCPT ); Mon, 31 Jan 2022 15:45:34 -0500 Received: from mail-lj1-x230.google.com (mail-lj1-x230.google.com [IPv6:2a00:1450:4864:20::230]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6579DC061741 for ; Mon, 31 Jan 2022 12:45:34 -0800 (PST) Received: by mail-lj1-x230.google.com with SMTP id t7so21111310ljc.10 for ; Mon, 31 Jan 2022 12:45:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=OP8lq+CNNstsD6MdqxQkt/+Qf2pjO5hiMrphojuZwoU=; b=N1MCHAoWUOlYLJDlA8wsBKE17FbxUlNpj1KofdDJGYesdQY9l1rVYYgINrRkUaFZBf KZNoHtazLOFrvgO9HPbhkQGgMOkNa9WzmFHFsFTH/M9qA1u3o9csud+Tm3UjgZ2VXRRD MBJdqlKmhqMj9/7feMzK7v3gFyZRAULTAPFyDEKazMIngNZsWxfMaLlpzKLS16prACCB asGdmQF+SIIfQ7UskfAH9aJ7LdR7aWz737U8q97afIlghe20cwOmwee5S9cmVI84d7ND wNXe1uIhJrSlDO6Uso3Aw5t0JLY2/d0ne0JionMT8Xtu2qOll51EJMY/rmU8W8unvURw tMsg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=OP8lq+CNNstsD6MdqxQkt/+Qf2pjO5hiMrphojuZwoU=; b=zSmzH3nYSa4O7CD5AKsZ4hMUexbaVYRsIoBCGR0jkCzrq38k08Q6SFClDZ1Vv03Syj 46f/fFK1ujJw2GrQs3DVS42NA7jgbBvV9YUt9ZNdUlUE8az4bSXPfvYC5iKqy66jfET7 3hFQUXh6+2xHkR3g8auwbPowOTnndGK0btGAK16c4LEUNBLE9mtOhDArOhMzbM4YF0we cIBUrCw+UDLaLo1gE48BS7+8hfopA+kJO+4zJOku+ZEHXQw+TeDes/HCqmcLyxOgwtVZ 8zBfFSc8lJm6nBNZhenM0rWsi+ge9nvY659bPC82NY8zhoWv4l/MKWAnkAT8g77kNm8Q t5jQ== X-Gm-Message-State: AOAM530x/MWQ00QEAe5eBwk4eFqfaCe28CcB+upFJHo4MSzy351tVBbJ bxsV3jE99pVMZesHudAi3j4XmDzhkcK1IRtGyuv3+w== X-Google-Smtp-Source: ABdhPJyUGs/IuSxxzyGQxz64BV96QhIOuwlW+Oh1fnhj7wrQYLrrNl3HYHpoA3JpS27Xsbp+jya9RNlM8rpDYvQ9TSo= X-Received: by 2002:a2e:954:: with SMTP id 81mr5661437ljj.198.1643661932405; Mon, 31 Jan 2022 12:45:32 -0800 (PST) MIME-Version: 1.0 References: <20220114010526.1776605-1-ndesaulniers@google.com> <20220118192256.jzk5dnceeusq7x7u@treble> <20220118230120.pivvson7qekfiqic@treble> <20220125233128.GT614@gate.crashing.org> In-Reply-To: <20220125233128.GT614@gate.crashing.org> From: Nick Desaulniers Date: Mon, 31 Jan 2022 12:45:20 -0800 Message-ID: Subject: Re: [PATCH] objtool: prefer memory clobber & %= to volatile & __COUNTER__ To: Segher Boessenkool , apinski@marvell.com Cc: Josh Poimboeuf , Borislav Petkov , 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 , linux-toolchains@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 25, 2022 at 3:34 PM Segher Boessenkool wrote: > > Hi! > > On Mon, Jan 24, 2022 at 03:26:36PM -0800, Nick Desaulniers wrote: > > I'm more confident that we can remove the `volatile` keyword (I was > > thinking about adding a new diagnostic to clang to warn that volatile > > is redundate+implied for asm goto or inline asm that doesn't have > > outputs) though that's not the problem here and will probably generate > > some kernel wide cleanup before we could enable such a flag. > > Its main value is that it would discourage users from thinking volatile > is magic. Seriously worth some pain! https://reviews.llvm.org/D118297 PTAL -- Thanks, ~Nick Desaulniers