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 2675CC4332F for ; Wed, 4 Jan 2023 11:36:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234704AbjADLg3 (ORCPT ); Wed, 4 Jan 2023 06:36:29 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52884 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234645AbjADLg2 (ORCPT ); Wed, 4 Jan 2023 06:36:28 -0500 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 032EFAE7B; Wed, 4 Jan 2023 03:36:27 -0800 (PST) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 4F7021042; Wed, 4 Jan 2023 03:37:08 -0800 (PST) Received: from FVFF77S0Q05N (unknown [10.57.37.146]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D24573F587; Wed, 4 Jan 2023 03:36:20 -0800 (PST) Date: Wed, 4 Jan 2023 11:36:18 +0000 From: Mark Rutland To: Arnd Bergmann Cc: Peter Zijlstra , Boqun Feng , Linus Torvalds , Jonathan Corbet , Will Deacon , Catalin Marinas , dennis@kernel.org, Tejun Heo , Christoph Lameter , Heiko Carstens , gor@linux.ibm.com, Alexander Gordeev , borntraeger@linux.ibm.com, svens@linux.ibm.com, Herbert Xu , "David S . Miller" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , joro@8bytes.org, suravee.suthikulpanit@amd.com, Robin Murphy , dwmw2@infradead.org, baolu.lu@linux.intel.com, Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Vlastimil Babka , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-s390@vger.kernel.org, linux-crypto@vger.kernel.org, iommu@lists.linux.dev, Linux-Arch Subject: Re: [RFC][PATCH 05/12] arch: Introduce arch_{,try_}_cmpxchg128{,_local}() Message-ID: References: <20221219153525.632521981@infradead.org> <20221219154119.154045458@infradead.org> <8fea3494-1d1f-4f64-b525-279152cf430b@app.fastmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8fea3494-1d1f-4f64-b525-279152cf430b@app.fastmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Tue, Jan 03, 2023 at 05:50:00PM +0100, Arnd Bergmann wrote: > On Tue, Jan 3, 2023, at 17:19, Mark Rutland wrote: > > On Tue, Jan 03, 2023 at 02:03:37PM +0000, Mark Rutland wrote: > >> On Tue, Jan 03, 2023 at 01:25:35PM +0000, Mark Rutland wrote: > >> > On Tue, Dec 20, 2022 at 12:08:16PM +0100, Peter Zijlstra wrote: > > >> ... makes GCC much happier: > > > >> ... I'll go check whether clang is happy with that, and how far back that can > >> go, otherwise we'll need to blat the high half with a separate constaint that > >> (ideally) doesn't end up allocating a pointless address register. > > > > Hmm... from the commit history it looks like GCC prior to 5.1 might not be > > happy with that, but that *might* just be if we actually do arithmetic on the > > value, and we might be ok just using it for memroy effects. I can't currently > > get such an old GCC to run on my machines so I haven't been able to check. > > gcc-5.1 is the oldest (barely) supported compiler, the minimum was > last raised from gcc-4.9 in linux-5.15. If only gcc-4.9 and older are > affected, we're good on mainline but may still want a fix for stable > kernels. Yup; I just wanted something that would easily backport to stable, at least as far as linux-4.9.y (where I couldn't find the minimum GCC version when I looked yesterday). > I checked that the cross-compiler binaries from [1] still work, but I noticed > that this version is missing the native aarch64-to-aarch64 compiler (x86 to > aarch64 and vice versa are there), and you need to install libmpfr4 [2] > as a dependency. The newer compilers (6.5.0 and up) don't have these problems. I was trying the old kernel.org crosstool binaries, but I was either missing a library (or I have an incompatible version) on my x86_64 host. I'll have another look today -- thanks for the pointers! Mark. > Arnd > > [1] https://mirrors.edge.kernel.org/pub/tools/crosstool/files/bin/arm64/5.5.0/ > [2] http://ftp.uk.debian.org/debian/pool/main/m/mpfr4/libmpfr4_3.1.5-1_arm64.deb