Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751210AbeADXJb (ORCPT + 1 other); Thu, 4 Jan 2018 18:09:31 -0500 Received: from mail-qt0-f176.google.com ([209.85.216.176]:34605 "EHLO mail-qt0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751029AbeADXJ3 (ORCPT ); Thu, 4 Jan 2018 18:09:29 -0500 X-Google-Smtp-Source: ACJfBotJB1upBfCJORAEyVPrmDHJa9+CKIbIJWLPy0iBw8934y+3y9ZnEpfLM5JLMWmXpuLQvZEkeIvppTJl2VyzW9w= MIME-Version: 1.0 In-Reply-To: <9f274ca7-732d-810a-4e51-83309b96d14b@physik.tu-berlin.de> References: <9f274ca7-732d-810a-4e51-83309b96d14b@physik.tu-berlin.de> From: Tony Luck Date: Thu, 4 Jan 2018 15:09:28 -0800 Message-ID: Subject: Re: proposal for meltdown-workaround with low overhead To: Alexander Kleinsorge Cc: Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: On Thu, Jan 4, 2018 at 11:45 AM, Alexander Kleinsorge wrote: > As Meltdown-Issue depends on allowing to cause many exceptions (usually : > accessing an invalid address), we could restrict this misusage easy. The accesses to the invalid address are performed speculatively by the CPU in a code branch that is later found to be not taken. Hence there are no exceptions at all. -Tony