From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964836AbdKBTiH (ORCPT ); Thu, 2 Nov 2017 15:38:07 -0400 Received: from mga04.intel.com ([192.55.52.120]:37342 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934065AbdKBTiG (ORCPT ); Thu, 2 Nov 2017 15:38:06 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.44,335,1505804400"; d="scan'208";a="168555298" Subject: Re: [PATCH 00/23] KAISER: unmap most of the kernel from userspace page tables To: Will Deacon References: <20171031223146.6B47C861@viggo.jf.intel.com> <20171102190106.GC22263@arm.com> Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org From: Dave Hansen Message-ID: <816a3491-3c2c-ec0a-810f-b593c25968f2@linux.intel.com> Date: Thu, 2 Nov 2017 12:38:05 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: <20171102190106.GC22263@arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/02/2017 12:01 PM, Will Deacon wrote: > 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. Welcome to the party! I don't know if you've found anything different, but there been woefully little code that's really cross-architecture. The kernel task stack-mapping stuff _was_, but it's going away. The per-cpu-user-mapped section stuff might be common, I guess. Is there any other common infrastructure that we can or should be sharing?