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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 5428AC43331 for ; Mon, 11 Nov 2019 14:39:26 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 1153F2245C for ; Mon, 11 Nov 2019 14:39:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="PZ/Jr2D1" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1153F2245C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-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=bombadil.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=+nrHEA++HmN256FANw+cZPgowGlU0BDYHopkUJfy0tI=; b=PZ/Jr2D1NIm4gcm6CXi6ahFdm JroLbitbCp+XO4BgCHvYjnSR6baHkt/LTJZu4qicRFFZ6A/720J0/8J4JNMfevpaub+K6d3z1kRmQ 7MulSipMjBQIFka/Zq0hUjGKdSWbkrOyK4oQoLlPgrVrg1mgk/Bo1ZalYRezrUb9l7jFHI4aK8FAw yMH6lYwOIth89pMURgDk+ZMV+cqsHGsiulTIKi5F6ZWdz4UsMnRzyuybNXP47X7DugEvbVBrt5jqN Wy44DKZMqdeHwAeMTbxnP3vIxHH8rPImQqCkxvJB8S041MOtl2ih03BYCQFIwcsbUufNath49axEb ayFsfPcvg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iUAqi-0000IH-RK; Mon, 11 Nov 2019 14:39:24 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iUAqe-0000Hu-T5 for linux-arm-kernel@lists.infradead.org; Mon, 11 Nov 2019 14:39:23 +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 F422431B; Mon, 11 Nov 2019 06:39:19 -0800 (PST) Received: from localhost.localdomain (unknown [10.1.196.67]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 65F243F52E; Mon, 11 Nov 2019 06:39:19 -0800 (PST) Subject: Re: [PATCH v8 4/4] arm64: Use a variable to store non-global mappings decision To: Mark Brown , Catalin Marinas , Will Deacon References: <20191108170116.32105-1-broonie@kernel.org> <20191108170116.32105-5-broonie@kernel.org> From: Suzuki K Poulose Message-ID: Date: Mon, 11 Nov 2019 14:39:18 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.0 MIME-Version: 1.0 In-Reply-To: <20191108170116.32105-5-broonie@kernel.org> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191111_063920_978281_4F9C01E7 X-CRM114-Status: GOOD ( 16.54 ) 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: linux-arm-kernel@lists.infradead.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 08/11/2019 17:01, Mark Brown wrote: > Refactor the code which checks to see if we need to use non-global > mappings to use a variable instead of checking with the CPU capabilities > each time, doing the initial check for KPTI early in boot before we > start allocating memory so we still avoid transitioning to non-global > mappings in common cases. > > Since this variable always matches our decision about non-global > mappings this means we can also combine arm64_kernel_use_ng_mappings() > and arm64_unmap_kernel_at_el0() into a single function, the variable > simply stores the result and the decision code is elsewhere. We could > just have the users check the variable directly but having a function > makes it clear that these uses are read-only. > > The result is that we simplify the code a bit and reduces the amount of > code executed at runtime. > > Signed-off-by: Mark Brown Reviewed-by: Suzuki K Poulose _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel