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=-9.0 required=3.0 tests=BAYES_00,INCLUDES_PATCH, MAILING_LIST_MULTI,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 63441C433DB for ; Mon, 11 Jan 2021 13:41:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4788022203 for ; Mon, 11 Jan 2021 13:41:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733246AbhAKNle (ORCPT ); Mon, 11 Jan 2021 08:41:34 -0500 Received: from mail.kernel.org ([198.145.29.99]:47962 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733235AbhAKNlb (ORCPT ); Mon, 11 Jan 2021 08:41:31 -0500 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9137D221FD; Mon, 11 Jan 2021 13:40:50 +0000 (UTC) Received: from disco-boy.misterjones.org ([51.254.78.96] helo=www.loen.fr) by disco-boy.misterjones.org with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94) (envelope-from ) id 1kyxRA-006gvt-Gn; Mon, 11 Jan 2021 13:40:48 +0000 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Mon, 11 Jan 2021 13:40:48 +0000 From: Marc Zyngier To: Srinivas Ramana Cc: catalin.marinas@arm.com, will@kernel.org, pajay@qti.qualcomm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-arm-msm@vger.kernel.org Subject: Re: [PATCH 0/3] arm64: cpufeature: Add filter function to control In-Reply-To: <1610152163-16554-1-git-send-email-sramana@codeaurora.org> References: <1610152163-16554-1-git-send-email-sramana@codeaurora.org> User-Agent: Roundcube Webmail/1.4.9 Message-ID: <6dfdf691b5ed57df81c4c61422949af5@misterjones.org> X-Sender: maz@kernel.org X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: sramana@codeaurora.org, catalin.marinas@arm.com, will@kernel.org, pajay@qti.qualcomm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-arm-msm@vger.kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org Hi Srinivas, On 2021-01-09 00:29, Srinivas Ramana wrote: > This patchset adds a control function for cpufeature framework > so that the feature can be controlled at runtime. > > Defer PAC on boot core and use the filter function added to disable > PAC from command line. This will help toggling the feature on systems > that do not support PAC or where PAC needs to be disabled at runtime, > without modifying the core kernel. > > The idea of adding the filter function for cpufeature is taken from > https://lore.kernel.org/linux-arm-kernel/20200515171612.1020-25-catalin.marinas@arm.com/ > https://lore.kernel.org/linux-arm-kernel/20200515171612.1020-24-catalin.marinas@arm.com/ > > Srinivas Ramana (3): > arm64: Defer enabling pointer authentication on boot core > arm64: cpufeature: Add a filter function to cpufeature > arm64: Enable control of pointer authentication using early param > > Documentation/admin-guide/kernel-parameters.txt | 6 +++ > arch/arm64/include/asm/cpufeature.h | 8 +++- > arch/arm64/include/asm/pointer_auth.h | 10 +++++ > arch/arm64/include/asm/stackprotector.h | 1 + > arch/arm64/kernel/cpufeature.c | 53 > +++++++++++++++++++------ > arch/arm64/kernel/head.S | 4 -- > 6 files changed, 64 insertions(+), 18 deletions(-) I've been working for some time on a similar series to allow a feature set to be disabled during the early boot phase, initially to prevent booting a kernel with VHE, but the mechanism is generic enough to deal with most architectural features. I took the liberty to lift your first patch and to add it to my series[1], further allowing PAuth to be disabled at boot time on top of BTI and VHE. I'd appreciate your comments on this. Thanks, M. [1] https://lore.kernel.org/r/20210111132811.2455113-1-maz@kernel.org -- Jazz is not dead. It just smells funny...