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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 B3201C433E0 for ; Tue, 26 Jan 2021 11:44:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 78DA323110 for ; Tue, 26 Jan 2021 11:44:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2405268AbhAZLoJ (ORCPT ); Tue, 26 Jan 2021 06:44:09 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57786 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404858AbhAZLIC (ORCPT ); Tue, 26 Jan 2021 06:08:02 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F3C9DC061573 for ; Tue, 26 Jan 2021 03:07:21 -0800 (PST) Date: Tue, 26 Jan 2021 12:07:16 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1611659236; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=ZkPU/hX7e8KAUGBs+8Xq5YFkeqG2HTJf4MGRstA6AwQ=; b=LOTtMY+pdaRCJZdqDkCezplZ9/BMaIWcDNsxGxhj94CLTHbHuUp3HyswBpFH1FN2MJPdGi 61MfuHrBzJf4yQOm+6nby3m8VAi3BBb1McepZQ1M1kkxRj9xxV+oFZxbsqEguT589nNF5u XEvPVHmeQhCkPc6kzDoRCz1OxEwURtUepaHKDSzkbjJU32Jly8o3SgmhyYvSYqv4zrQa4/ HSHgOT9BAJAgIoxq24O9f+0Z6JKjyzcggoXd2+YRVoWgytVQHXApbMk2QvQ8Eq8mRhYwo0 n3dE3tFzcxB9O5I8+DWu2H5WMX2wqOVdGnFa1i9pqNtHplQYto2YkptDjJtv2Q== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1611659236; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=ZkPU/hX7e8KAUGBs+8Xq5YFkeqG2HTJf4MGRstA6AwQ=; b=a70BsVVvtj11dHf5ptAh7cMCsdzynscjtdvw5MMb3ErI/Q3ljLaTONjD5UE6pu2PSjcgLp mKYFa1Ua4HbpadCA== From: Sebastian Andrzej Siewior To: Russell King - ARM Linux admin Cc: Lecopzer Chen , akpm@linux-foundation.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, marc.zyngier@arm.com, peterx@redhat.com, rppt@kernel.org, walken@google.com, yj.chiang@mediatek.com, tglx@linutronix.de Subject: Re: [PATCH] ARM: mm: harden branch predictor before opening interrupts during fault Message-ID: <20210126110716.wv4igts76n3kg3ch@linutronix.de> References: <20201203092738.11866-1-lecopzer.chen@mediatek.com> <20210126091708.3461-1-lecopzer.chen@mediatek.com> <20210126105932.GG1551@shell.armlinux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20210126105932.GG1551@shell.armlinux.org.uk> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021-01-26 10:59:32 [+0000], Russell King - ARM Linux admin wrote: > On Tue, Jan 26, 2021 at 05:17:08PM +0800, Lecopzer Chen wrote: > > Hi all, > > > > I don't see any fix for this issue now(maybe I missed it..?), > > could we fix this if there is better solution? > > This issue exists almost two years. > > I don't think anyone provided an acceptable patch. > > The first patch moved the hardening out of the translation/section > fault handling. Since the kernel is mapped with sections, these > are above TASK_SIZE, and the whole point of the branch prediction > hardening is to prevent the prediction in the kernel being exploited, > missing the hardening effectively makes the mitigation useless. > > The discussion in February 2019 never concluded from what I can see. My memory is that I never got a reply which I understood. Let me try again this week with the information above. Sebastian