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=-10.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 249A8C433FF for ; Mon, 29 Jul 2019 20:32:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DFA7120679 for ; Mon, 29 Jul 2019 20:32:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="GKAMRd+s" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728663AbfG2Ucv (ORCPT ); Mon, 29 Jul 2019 16:32:51 -0400 Received: from mail-wm1-f68.google.com ([209.85.128.68]:50370 "EHLO mail-wm1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728189AbfG2Ucv (ORCPT ); Mon, 29 Jul 2019 16:32:51 -0400 Received: by mail-wm1-f68.google.com with SMTP id v15so55051065wml.0 for ; Mon, 29 Jul 2019 13:32:49 -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:user-agent; bh=Ee1tMJewpz3aSk+3Cf8f90eAN6SRg/eYiUnStRjgYLc=; b=GKAMRd+sTnkw9Z5FKHUDESOtOokR4c4LKf+jO5xxjeSjB57EumDZ/CxDxRuPx5o04c OOkO4iV+suXKl3yH0dFExABiXBZteawHydX44sNNpKwCoNqPkRrjAcNWaUL1JPwHiXDt i9ODh5Q9p+tG2eaVD37/+XAMw/WcEH36Yo9Z+UvpDZ7FUdKsKch/axOhYZPg57pKoeQS Hyb4Uzezdex64lvLHXl5cVC0f2v1lfQan8CB1xPFNR6buLIGB/bq7uby93buNGR9leQB E7IXah2txsckO3Ju25p+/cJv0doqIxdkhbzw3zM+4CkbAf4HdVfFDABA/5uKlCk03eHY uKyA== 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:user-agent; bh=Ee1tMJewpz3aSk+3Cf8f90eAN6SRg/eYiUnStRjgYLc=; b=DwFg0tGFjwMHWQ+B8zFwdBCNoFeEfTh1TR0vRIFjzr3A584Bbe0XAvwiVR8HeQM879 rTatJZXSSTbgvLYp74pYzxBpOQknLjL63gq+LXPrpoZNEc/t0exK3GbHOAoQx3pR1GiF xPxqHEjrWitm/bmli1y6bmc7ZtRGRCj2qVjq2qGPXi6b3N/blwnJ+pdcA+QKEAFp8GHN NTilO2WFPqDtrPAEeRcxgCoqPYDkL9zPIyymL/J0of7jrU081MBYUnJBheDFBAjxK7o7 6iSzn+S8IwxRS8dsas/RkGc0HHuQjpshcPeHtlfbFn0MsqbDyUx9cAV1ruKlOqcE6LX5 Bkbw== X-Gm-Message-State: APjAAAVATCj1wu3MMqkNS/VSnJKxjHkyk1XyZAsj+2edhw0smyDiDyfg e7FzcPuCYAjGsyjm97BEd0A= X-Google-Smtp-Source: APXvYqyo7SE3N8MZySPqPna98P9GkU1XLHH7+P2p4LKXp1/uIewGRNlsiTkEr1RxTwquxX5I1q0klQ== X-Received: by 2002:a1c:a019:: with SMTP id j25mr100975707wme.95.1564432368772; Mon, 29 Jul 2019 13:32:48 -0700 (PDT) Received: from archlinux-threadripper ([2a01:4f8:222:2f1b::2]) by smtp.gmail.com with ESMTPSA id t24sm56680198wmj.14.2019.07.29.13.32.47 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Mon, 29 Jul 2019 13:32:48 -0700 (PDT) Date: Mon, 29 Jul 2019 13:32:46 -0700 From: Nathan Chancellor To: Nick Desaulniers Cc: mpe@ellerman.id.au, christophe.leroy@c-s.fr, segher@kernel.crashing.org, arnd@arndb.de, kbuild test robot , Benjamin Herrenschmidt , Paul Mackerras , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com Subject: Re: [PATCH] powerpc: workaround clang codegen bug in dcbz Message-ID: <20190729203246.GA117371@archlinux-threadripper> References: <20190729202542.205309-1-ndesaulniers@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190729202542.205309-1-ndesaulniers@google.com> User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 29, 2019 at 01:25:41PM -0700, Nick Desaulniers wrote: > Commit 6c5875843b87 ("powerpc: slightly improve cache helpers") exposed > what looks like a codegen bug in Clang's handling of `%y` output > template with `Z` constraint. This is resulting in panics during boot > for 32b powerpc builds w/ Clang, as reported by our CI. > > Add back the original code that worked behind a preprocessor check for > __clang__ until we can fix LLVM. > > Further, it seems that clang allnoconfig builds are unhappy with `Z`, as > reported by 0day bot. This is likely because Clang warns about inline > asm constraints when the constraint requires inlining to be semantically > valid. > > Link: https://bugs.llvm.org/show_bug.cgi?id=42762 > Link: https://github.com/ClangBuiltLinux/linux/issues/593 > Link: https://lore.kernel.org/lkml/20190721075846.GA97701@archlinux-threadripper/ > Debugged-by: Nathan Chancellor > Reported-by: Nathan Chancellor > Reported-by: kbuild test robot > Suggested-by: Nathan Chancellor > Signed-off-by: Nick Desaulniers > --- > Alternatively, we could just revert 6c5875843b87. It seems that GCC > generates the same code for these functions for out of line versions. > But I'm not sure how the inlined code generated would be affected. For the record: https://godbolt.org/z/z57VU7 This seems consistent with what Michael found so I don't think a revert is entirely unreasonable. Either way: Reviewed-by: Nathan Chancellor