From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934240AbdKBTBF (ORCPT ); Thu, 2 Nov 2017 15:01:05 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:35808 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932571AbdKBTBE (ORCPT ); Thu, 2 Nov 2017 15:01:04 -0400 Date: Thu, 2 Nov 2017 19:01:07 +0000 From: Will Deacon To: Dave Hansen Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH 00/23] KAISER: unmap most of the kernel from userspace page tables Message-ID: <20171102190106.GC22263@arm.com> References: <20171031223146.6B47C861@viggo.jf.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171031223146.6B47C861@viggo.jf.intel.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Dave, [+linux-arm-kernel] On Tue, Oct 31, 2017 at 03:31:46PM -0700, Dave Hansen wrote: > KAISER makes it harder to defeat KASLR, but makes syscalls and > interrupts slower. These patches are based on work from a team at > Graz University of Technology posted here[1]. The major addition is > support for Intel PCIDs which builds on top of Andy Lutomorski's PCID > work merged for 4.14. PCIDs make KAISER's overhead very reasonable > for a wide variety of use cases. I just wanted to say that I've got a version of this up and running for arm64. I'm still ironing out a few small details, but I hope to post it after the merge window. We always use ASIDs, and the perf impact looks like it aligns roughly with your findings for a PCID-enabled x86 system. Cheers, Will