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=-12.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 8836CC433FE for ; Sat, 12 Dec 2020 05:54:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4E8952313C for ; Sat, 12 Dec 2020 05:54:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733091AbgLLFxo (ORCPT ); Sat, 12 Dec 2020 00:53:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45456 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725963AbgLLFxM (ORCPT ); Sat, 12 Dec 2020 00:53:12 -0500 Received: from mail-io1-xd44.google.com (mail-io1-xd44.google.com [IPv6:2607:f8b0:4864:20::d44]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6B51AC0613D3; Fri, 11 Dec 2020 21:52:32 -0800 (PST) Received: by mail-io1-xd44.google.com with SMTP id y5so11756313iow.5; Fri, 11 Dec 2020 21:52:32 -0800 (PST) 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; bh=de8qBW77ez2vG1k7g514vZ/gVwv8ByEiy7/gkUkjT1M=; b=vREtwM0YGPhQ/XD++8S3cVIT38mJng6WEpGZ2IoNGpR1vrFbqwryxq/RwTbzBNeyut ITQ2hlZyPNFcERgd6FfztKl+kQ/i0879wT6u5C4ITw1uPliT0BP3aXC3yGWs3G9l5d0r fHAi+dIC2C1a8TTHFbt5oiAosHDLBP/ZZ+CDZbc88lVkGgG8+y3UMj+sN+eUM/dRxylR g78ILa3OWWHTQjCDEVmfDuTf0B2H5nG03gcsc31nsKGwSrSMKhB4dFJxFy0zP31kFoos jF3WVRVQ3rFgx8b1wQbpPXnzSZKIEF3PRmxRx9afR9zqevYdETq9dJCvgJtBBGHeUepN i+3Q== 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; bh=de8qBW77ez2vG1k7g514vZ/gVwv8ByEiy7/gkUkjT1M=; b=fyH8YABECefg61h7ppufZ3WeIv2L57U12TNS7TqHad5ffJ9+gtsUr2x3UZY3gFNIj4 7NGfSTJauTa58yjI0PTnTnNrNqZVxMNKOElcrXN2pAzH8QCksZhaZClJMribgsNwFTJx cxDnQWFFE3OXq1GjDjeELAERmhx+IY8XbWneMev75v9rf4t52I4noXHEyKq1RUehfzSw fi/HLpKcykGnSJchT0ZtJDdmlDU3We9a8EctLCe5fRJZJSYaHdFr7sNruQKHH/ekAFxC 5/rbYK2mp1xhhkewF2oCVfRpUByK+t2hzO9dS1wmUpM2YTLFM4gws5g9b4Ddj1wTIPb/ jkxw== X-Gm-Message-State: AOAM532JIp6A+a/4778oCQEZE/wOILB7NIToNHvPg8IB0+bLB7bxdSOc wBllinlloBibU3+ColxgKGc= X-Google-Smtp-Source: ABdhPJyIvcNYPBRy8ETgODWko7PYHuwoeJSdT+Ep4FOV4A/DgsWNsQZ/SHxOfg4PptQZ7xHi0/CkOQ== X-Received: by 2002:a05:6638:5b2:: with SMTP id b18mr20364316jar.69.1607752351667; Fri, 11 Dec 2020 21:52:31 -0800 (PST) Received: from ubuntu-m3-large-x86 ([2604:1380:45f1:1d00::1]) by smtp.gmail.com with ESMTPSA id 143sm6795278ila.4.2020.12.11.21.52.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 11 Dec 2020 21:52:30 -0800 (PST) Date: Fri, 11 Dec 2020 22:52:28 -0700 From: Nathan Chancellor To: "Maciej W. Rozycki" Cc: Anders Roxell , tsbogend@alpha.franken.de, ndesaulniers@google.com, linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com Subject: Re: [PATCH v2] mips: lib: uncached: fix non-standard usage of variable 'sp' Message-ID: <20201212055228.GA823758@ubuntu-m3-large-x86> References: <20201211102437.3929348-1-anders.roxell@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 11, 2020 at 07:54:07PM +0000, Maciej W. Rozycki wrote: > On Fri, 11 Dec 2020, Anders Roxell wrote: > > > diff --git a/arch/mips/lib/uncached.c b/arch/mips/lib/uncached.c > > index 09d5deea747f..f80a67c092b6 100644 > > --- a/arch/mips/lib/uncached.c > > +++ b/arch/mips/lib/uncached.c > > @@ -37,10 +37,12 @@ > > */ > > unsigned long run_uncached(void *func) > > { > > - register long sp __asm__("$sp"); > > register long ret __asm__("$2"); > > long lfunc = (long)func, ufunc; > > long usp; > > + long sp; > > + > > + __asm__("move %0, $sp" : "=r" (sp)); > > I thought it might be better to make `sp' global instead, so that it's > the compiler that chooses how to schedule accesses. Have you tried that? > > Maciej This will not work, as the LLVM Mips backend does not support using $sp as a global register variable: https://github.com/llvm/llvm-project/commit/1440bb2a26ff13df1b29762658ee122cc0bc47ae $ make -skj"$(nproc)" ARCH=mips CROSS_COMPILE=mipsel-linux-gnu- LLVM=1 O=out \ distclean malta_kvm_guest_defconfig vmlinux fatal error: error in backend: Invalid register name global variable ... Cheers, Nathan