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=-11.3 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, NICE_REPLY_A,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 84E53C433DF for ; Tue, 11 Aug 2020 04:48:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5709A20678 for ; Tue, 11 Aug 2020 04:48:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=mg.codeaurora.org header.i=@mg.codeaurora.org header.b="Qzl5bTDq" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726703AbgHKEs3 (ORCPT ); Tue, 11 Aug 2020 00:48:29 -0400 Received: from mail29.static.mailgun.info ([104.130.122.29]:43972 "EHLO mail29.static.mailgun.info" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726178AbgHKEs2 (ORCPT ); Tue, 11 Aug 2020 00:48:28 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1597121308; h=Content-Transfer-Encoding: Content-Type: In-Reply-To: MIME-Version: Date: Message-ID: From: References: Cc: To: Subject: Sender; bh=0cJt+WgRXB1nbIu2m8++kElnkIQWCS3PK5eceIKAvUk=; b=Qzl5bTDqN2qNflTHO9RLbXyMpFQYo5jiQCSYtRZVfe/Kzhk3I5dRwfp9ailoaqKFuYgKHyn5 nHqcsROxwY0Ipc5c5klqFXz3iAcL0ChLMXx6BbVgPI4Nmv4lT7jRDViu3laX7JFMt7QV8RMx 2jVTNWVqB1UFJexMPamIrqDzJv4= X-Mailgun-Sending-Ip: 104.130.122.29 X-Mailgun-Sid: WyI0MWYwYSIsICJsaW51eC1rZXJuZWxAdmdlci5rZXJuZWwub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n02.prod.us-east-1.postgun.com with SMTP id 5f32231491f8def8b2098408 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Tue, 11 Aug 2020 04:48:20 GMT Received: by smtp.codeaurora.org (Postfix, from userid 1001) id AC99BC433CA; Tue, 11 Aug 2020 04:48:19 +0000 (UTC) Received: from [192.168.1.4] (unknown [122.170.228.200]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: gkohli) by smtp.codeaurora.org (Postfix) with ESMTPSA id 2B6E8C433C9; Tue, 11 Aug 2020 04:48:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 2B6E8C433C9 Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=none smtp.mailfrom=gkohli@codeaurora.org Subject: Re: [PATCH] arm64: Skip apply SSBS call for non SSBS system To: will@kernel.org, linux-arm-kernel@lists.infradead.org, maz@kernel.org, Catalin Marinas Cc: linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, neeraju@codeaurora.org References: <1596550484-11029-1-git-send-email-gkohli@codeaurora.org> From: Gaurav Kohli Message-ID: <16e9b436-5919-39df-3f1a-a717d4229651@codeaurora.org> Date: Tue, 11 Aug 2020 10:18:13 +0530 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: <1596550484-11029-1-git-send-email-gkohli@codeaurora.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, Please let us know, is below patch good to have or not for non ssbs systems. On 8/4/2020 7:44 PM, Gaurav Kohli wrote: > In a system where no cpu's implement SSBS, for > them no need to set pstate. This might help to save > few cpu cycles during context switch. > > Signed-off-by: Gaurav Kohli > > diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c > index 6089638..79f80f1 100644 > --- a/arch/arm64/kernel/process.c > +++ b/arch/arm64/kernel/process.c > @@ -477,6 +477,13 @@ static void ssbs_thread_switch(struct task_struct *next) > struct pt_regs *regs = task_pt_regs(next); > > /* > + * For Targets which don't have SSBS support, they > + * can return from here. > + */ > + if (!IS_ENABLED(CONFIG_ARM64_SSBD)) > + return; > + > + /* > * Nothing to do for kernel threads, but 'regs' may be junk > * (e.g. idle task) so check the flags and bail early. > */ > -- Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.