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=-2.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED,USER_AGENT_MUTT 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 A5F50C4360F for ; Fri, 15 Feb 2019 18:20:57 +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 7ADE2222A1 for ; Fri, 15 Feb 2019 18:20:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="QIuyXYVw" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7ADE2222A1 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-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=rnXWGWPDwftjcUMZ7udbiaSygb+eUzpLR3661kqwflE=; b=QIuyXYVwjZCHuO lsEY2ZseJRtpidAq9X1dbLkFtDTIjfXGnEzLMrq/WlnA8zCGCVsHHK4/w5HsAnxtOeKWzgW0L4tdM 4Z7KHa0ZxiKJt08hMkWxK5lBZLNkcg6SEyz0hbfA3/E+zJaD2/zZzOoJJ/wE2od1LLiRXQMs1Ah5p 2q5BwMWs3XjioPO71BolO8IUxBW09W8DtbtaN/37w+t7ddhxpAG4kj+VTl6/qM1mxe9EjwIUkACbK seCsL9J+LBcDOxeUO8NLLeG72TbjSfgI+SAoFNFqFQePxc6rVXykZ1ooxXXdCaL9iC/OstG8XkZhN cqeiW79nsNDlPi8/koag==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gui6R-00080H-NI; Fri, 15 Feb 2019 18:20:47 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gui6O-0007zr-Qg for linux-arm-kernel@lists.infradead.org; Fri, 15 Feb 2019 18:20:46 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 899E0A78; Fri, 15 Feb 2019 10:20:43 -0800 (PST) Received: from arrakis.emea.arm.com (arrakis.cambridge.arm.com [10.1.196.78]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id DCE553F589; Fri, 15 Feb 2019 10:20:40 -0800 (PST) Date: Fri, 15 Feb 2019 18:20:38 +0000 From: Catalin Marinas To: Andre Przywara Subject: Re: [PATCH v4 03/12] arm64: Remove the ability to build a kernel without ssbd Message-ID: <20190215182037.GI100037@arrakis.emea.arm.com> References: <20190125180711.1970973-1-jeremy.linton@arm.com> <20190125180711.1970973-4-jeremy.linton@arm.com> <20190130180415.0cab24e0@donnerap.cambridge.arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190130180415.0cab24e0@donnerap.cambridge.arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190215_102044_869383_5B2F3026 X-CRM114-Status: GOOD ( 17.39 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: stefan.wahren@i2se.com, mlangsdo@redhat.com, suzuki.poulose@arm.com, marc.zyngier@arm.com, ykaukab@suse.de, julien.thierry@arm.com, will.deacon@arm.com, linux-kernel@vger.kernel.org, Jeremy Linton , steven.price@arm.com, Christoffer Dall , shankerd@codeaurora.org, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, dave.martin@arm.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Jan 30, 2019 at 06:04:15PM +0000, Andre Przywara wrote: > On Fri, 25 Jan 2019 12:07:02 -0600 > Jeremy Linton wrote: > > Buried behind EXPERT is the ability to build a kernel without > > SSBD, this needlessly clutters up the code as well as creates > > the opportunity for bugs. It also removes the kernel's ability > > to determine if the machine its running on is vulnerable. > > I don't know the original motivation for this config option, typically > they are not around for no reason. > I see the benefit of dropping those config options, but we want to make > sure that people don't start hacking around to remove them again. > > > Since its also possible to disable it at boot time, lets remove > > the config option. > > Given the level of optimisation a compiler can do with the state being > known at compile time, I would imagine that it's not the same (though > probably very close). > > But that's not my call, it would be good to hear some maintainer's > opinion on this. Having spoken to Will, we'd rather keep the config options if possible. Even if they are behind EXPERT and default y, they come in handy when debugging. Can we still have the sysfs information regardless of whether the config is enabled or not? IOW, move the #ifdefs around to always have the detection while being able to disable the actual workarounds via config? Are the code paths between config and cmdline disabling identical? At a quick look I got the impression they are not exactly the same. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel