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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 B7302C2BB1D for ; Thu, 12 Mar 2020 03:52:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AA6F1206E2 for ; Thu, 12 Mar 2020 03:52:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="vVMFSuX7" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387735AbgCLDwl (ORCPT ); Wed, 11 Mar 2020 23:52:41 -0400 Received: from mail-qt1-f195.google.com ([209.85.160.195]:41071 "EHLO mail-qt1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387453AbgCLDwl (ORCPT ); Wed, 11 Mar 2020 23:52:41 -0400 Received: by mail-qt1-f195.google.com with SMTP id l21so3304498qtr.8; Wed, 11 Mar 2020 20:52:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:from:date:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=WUYv968HTJjo1Mkp2/EuQ7/8GKIJ2nyGafz2Vr8qTVU=; b=vVMFSuX799qi1oZfkM763trW9w5t0dLOrZsD+gKWVTb+cnNmhasgRFnkZVGyWZh3aa Mq1aOr0aivlPh2BaZC2fTWQXFWfAOSE+uV9TeIPNCv4lRInrqOz5NGNb5he7AlpH5+Vn IcplsE90MjuAk2JQZJTyXmGrlo76pG/lH/lPERxK5chFrFY6k4ZIAvAP9iXUqQv1+wf8 A5ivCiLHvrAytRq8uFCzpYHkUWUNJDdSxOIhxPQIWdwnvvR3oXsviVm5uCb3bwNkVsJo f8MWSlFm9B8qibj5U0gje3m022CRZ2OOZ+NfMjME9LHSP5GG+mSYxGpFeiqElrOIY4pt EOZw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:from:date:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to:user-agent; bh=WUYv968HTJjo1Mkp2/EuQ7/8GKIJ2nyGafz2Vr8qTVU=; b=FNNA4EyC0oLsch4bcvOZ8anQjgBw/Do/51h6eb+ZVtMswRMmXCUHIniblrft/2rIrJ NRb80RRRjFyaklQSVPfzdiIlPRbsPh3ShRbkqVqNWiph73Vjv8RKfTc5hv/avlwIT5NT Zt0FCZw0sS/Ui3RJAt4HmMVTlVhlomIX4+c1Oe/n87P1jWmDfndF1FhJ09N1OF6N2VCj xb3WZZWF73WVms7lbKUmAMRqAFk0rDe3NsP9uMFI94FhgEv6xXrI7RR1dqsuEn09T0Ae CAgceCb2TgknJpSPQmcpzZ4Q41XZW/mTXY7Z04XLGPsFlzR0VrsDpAovIvluYNSUMJrt EPGw== X-Gm-Message-State: ANhLgQ2n9knsb69KfcS35WXJOtEwn4AF5dbU28tbMQNYFHbOW4F0WZxx +BIO5k8+BvkdL+IBPZt2g3mLt+fMgdQ= X-Google-Smtp-Source: ADFU+vsr7Qn8d5IsLiuWpSqtsp+6BR3IFdwwAKdoOOHKkgW9qSF96V8Tse0BhdrAktQUvAmOzrFgwA== X-Received: by 2002:ac8:4cc9:: with SMTP id l9mr5461056qtv.207.1583985159524; Wed, 11 Mar 2020 20:52:39 -0700 (PDT) Received: from rani.riverdale.lan ([2001:470:1f07:5f3::b55f]) by smtp.gmail.com with ESMTPSA id x1sm7836549qkl.128.2020.03.11.20.52.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Mar 2020 20:52:39 -0700 (PDT) From: Arvind Sankar X-Google-Original-From: Arvind Sankar Date: Wed, 11 Mar 2020 23:52:37 -0400 To: Pavel Machek Cc: Greg Kroah-Hartman , linux-kernel@vger.kernel.org, stable@vger.kernel.org, Ard Biesheuvel , Ingo Molnar , linux-efi@vger.kernel.org, Thomas Gleixner Subject: Re: [PATCH 4.19 84/86] efi/x86: Handle by-ref arguments covering multiple pages in mixed mode Message-ID: <20200312035235.GA270934@rani.riverdale.lan> References: <20200310124530.808338541@linuxfoundation.org> <20200310124535.409134291@linuxfoundation.org> <20200311130106.GB7285@duo.ucw.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200311130106.GB7285@duo.ucw.cz> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 11, 2020 at 02:01:07PM +0100, Pavel Machek wrote: > We don't really need to do this computation on pa, it would work on va > as well, right? It does not matter much, but old code worked that way. > > Plus, strictly speaking, pa + size can overflow for huge sizes, and > test will return false negatives. This is 64-bit code, overflow would need pa + size to be bigger than 2^64, and even then a false negative would need size to be around 2^64.