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=-11.6 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL 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 8FA01C433E1 for ; Fri, 14 Aug 2020 22:57:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5D8B22068E for ; Fri, 14 Aug 2020 22:57:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="OQpryg9I" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728226AbgHNW5p (ORCPT ); Fri, 14 Aug 2020 18:57:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59976 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726213AbgHNW5o (ORCPT ); Fri, 14 Aug 2020 18:57:44 -0400 Received: from mail-pj1-x1041.google.com (mail-pj1-x1041.google.com [IPv6:2607:f8b0:4864:20::1041]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9BFE7C061385 for ; Fri, 14 Aug 2020 15:57:44 -0700 (PDT) Received: by mail-pj1-x1041.google.com with SMTP id l60so5083450pjb.3 for ; Fri, 14 Aug 2020 15:57:44 -0700 (PDT) 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=2WvgDPVRwH/G8nEvnfho4t/Ss9/BmgYz8A1j9g02WnU=; b=OQpryg9I4cG/dSW/SrgZxBRXXyp/Qj/GulMsUn3Q+9vXeng/xz7Lc7t16CW/uAg3Iv rFYDgSt+ze848j3oqtMs70gzuxOPhtP/KpCogeVWD5PqKlval6qRv/LBE10EZal9gket SaHnJ037Boip19JM1nN8pR3WsfakUIxhOOGH/INxraGPJoHeMR1o7BHORHVQ1hwNlzyc wVDWVNveOtQW1vFdT0E/WOMR5bx9gsmOyImAXbhT7UFyRNmqXD2x1uz3hnMY8GsgzS95 DxGpXG9PJ0BnVX4EQWgNUexBboinfatQII+LuPljY502D05CCwTUq1DVYRho3bKi0LvV v8cw== 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=2WvgDPVRwH/G8nEvnfho4t/Ss9/BmgYz8A1j9g02WnU=; b=HtX1VhcPbbRHBb0tGEf15XdCs9msrWKECyEGH3Qmjku/Vf3RYMLVqlMUYSY7pzQvC9 U4Ip/uBc1XuvIThzXpreHTs6u53+I0/R6ByealZUouHULB5nI/aWgcaaEcVu/qGaT45u znBx2HXIapaOtic6iTEu6/ojlv01OsBbl18Qbk9YbthOvEGxX++mIFbT6nho7ruUomxK tnMEd2h88BeI97yuHT5xi2yNT/J2I9WVS6+7VZgi8lWqePGFlcNAQvUkwqqv85Gqlr7R ktNyHdF32cjxfIpBgTyl7QxMeLUG3VlgdBCn/4r/vzIOkPj2PdUuYaxqy/NS6yS86nqn ozkg== X-Gm-Message-State: AOAM533PW4lbr4ycnFm/kn6XBtimswaoDxnK12hchuODY+c31D1x1PpG maQZqHtG5N5IloZ0VJldPsXxqxLc5kUVdKopVgYUMg== X-Google-Smtp-Source: ABdhPJwpHPvG+gANKUg+rLNbuVX3hvFnsRzQtxFawQdetHeWVZBNMiMYXAR3cXakSNIWhKz10qRqGt2jz00efQO6WWc= X-Received: by 2002:a17:90a:fc98:: with SMTP id ci24mr4046673pjb.101.1597445863888; Fri, 14 Aug 2020 15:57:43 -0700 (PDT) MIME-Version: 1.0 References: <20200527135329.1172644-1-arnd@arndb.de> In-Reply-To: From: Nick Desaulniers Date: Fri, 14 Aug 2020 15:57:31 -0700 Message-ID: Subject: Re: [PATCH] x86: work around clang IAS bug referencing __force_order To: Sedat Dilek Cc: Arnd Bergmann , Peter Collingbourne , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , "H. Peter Anvin" , "Kirill A. Shutemov" , Zhenzhong Duan , Kees Cook , Peter Zijlstra , Juergen Gross , Andy Lutomirski , Andrew Cooper , LKML , clang-built-linux Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Archived-At: List-Archive: List-Post: On Fri, Aug 14, 2020 at 2:19 PM Sedat Dilek wrote: > > On Fri, Aug 14, 2020 at 7:29 PM Sedat Dilek wrote: > > > > Thanks for the proposal. > > > > I have adapted it to fit my patchset against Linux v5.8. > > > > Both Debian's GCC-10 and a snapshot version of LLVM toolchain > > v11.0.0-rc1+ seems to be OK. > > > > Yupp, OK. > > I was able to boot FreeDOS 1.2 VM in VirtualBox GUI. Hi Sedat, Apologies, but it's not clear to me precisely which patch you tested. Can you please confirm whether you tested: 1. Arnd's patch that started this thread. 2. My proposed diff adding -fno-addrsig to CFLAGS_powernow-k6.o. 3. My proposed diff removing __force_order from the kernel. I'm hoping you were referring to testing 3., but it's not clear to me. I've been comparing the full disassemblies of vmlinux images when built with Clang with 3 applied (they're no different, which is a pleasant surprise, I didn't think kernel builds woulds would be fully deterministic given the sheer amount of source). I still need to check the compressed vmlinux image, and various .ko's (XEN) that use these read/write_cr[0,1,2,4]() functions, and then check them again when built with GCC. I'm falling behind a little trying to get our MC organized for plumbers, as well as the end of intern season and beginning of bi-annual "performance review" ("not stack ranking" I'm told) at work. If I don't find any differences, or if I do but don't find them to be meaningful, I hope to push a more formal patch (rather than just a diff) maybe next week. I'll include my findings either way; if it was 3 that you tested, I'll include your tested by tag when sending. Otherwise maybe you can help us test the more formal patch next week? -- Thanks, ~Nick Desaulniers