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=-5.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 19042C433FE for ; Mon, 7 Dec 2020 18:44:36 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A64822389A for ; Mon, 7 Dec 2020 18:44:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A64822389A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=lrIUR59L4EcjledqUyMQmsHuFfs3Vy3GTltvRRcDbEY=; b=rEivk5bD8WvJjOC0cSYFGofZT nUDpMaT8sKKcaHwk0qwp1rDMFiPpTah+/UVqLLfNeRFHnaCj3HfpaYf3XHHny1vMqoU0oXDEZP/Jx pYFwxebW3WSzHO46uENw231eCTQ4ihOJi46hSO7hfjVTVQ4FpyNyaenxLwRtEVYlqly8VcPVHeHJx D7HJFhkuR0s69bzvqseNa1Je798vLLoIhGNYtZZE3kW/ue9H6c1VlxVk916Hbj5my2DheOqZfAiog pscHpdGEwYLSPN056GD1fg/72KnqLbCBkOxH3VjrTO4ibsGsJLQ+DHJkQA2TLpDcM4JO+ED3qhCCr Nv5cQ2FWQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kmLTB-0003WP-3G; Mon, 07 Dec 2020 18:42:45 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kmLT8-0003W4-DH for linux-arm-kernel@lists.infradead.org; Mon, 07 Dec 2020 18:42:43 +0000 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 CD2AD1FB; Mon, 7 Dec 2020 10:42:25 -0800 (PST) Received: from [10.57.61.6] (unknown [10.57.61.6]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 983D03F66B; Mon, 7 Dec 2020 10:42:24 -0800 (PST) Subject: Re: [PATCH] arm64: Work around broken GCC handling of "S" constraint To: Ard Biesheuvel , Marc Zyngier References: <20201207154341.1004276-1-maz@kernel.org> <87316821c90a13a912a624250055f50f@kernel.org> From: Robin Murphy Message-ID: Date: Mon, 7 Dec 2020 18:42:23 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:78.0) Gecko/20100101 Thunderbird/78.5.1 MIME-Version: 1.0 In-Reply-To: Content-Language: en-GB X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201207_134242_543614_840B101A X-CRM114-Status: GOOD ( 14.62 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Will Deacon , Catalin Marinas , David Brazdil , Android Kernel Team , kvmarm , Linux ARM Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2020-12-07 17:47, Ard Biesheuvel wrote: > On Mon, 7 Dec 2020 at 18:41, Marc Zyngier wrote: >> >> On 2020-12-07 17:19, Ard Biesheuvel wrote: >>> (resend with David's email address fixed) >> >> Irk. Thanks for that. >> >>>>> +#ifdef CONFIG_CC_HAS_BROKEN_S_CONSTRAINT >>>>> +#define SYM_CONSTRAINT "i" >>>>> +#else >>>>> +#define SYM_CONSTRAINT "S" >>>>> +#endif >>>>> + >>>> >>>> Could we just check GCC_VERSION here? >> >> I guess we could. But I haven't investigated which exact range of >> compiler is broken (GCC 6.3 seems fixed, but that's the oldest >> I have apart from the offending 4.9). >> > > I tried 5.4 on godbolt, and it seems happy. And the failure will be > obvious, so we can afford to get it slightly wrong and refine it > later. FWIW the Linaro 14.11, 15.02 and 15.05 releases of GCC 4.9.3 seem to build rc7 without complaint. The only thing older that I have to hand is Ubuntu's GCC 4.8.4, which Kbuild chokes on entirely now. Robin. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel