Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753477AbdHIPjR (ORCPT ); Wed, 9 Aug 2017 11:39:17 -0400 Received: from mx2.suse.de ([195.135.220.15]:46123 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752510AbdHIPjP (ORCPT ); Wed, 9 Aug 2017 11:39:15 -0400 Subject: Re: [PATCH v2] x86/xen/64: Rearrange the SYSCALL entries To: Andy Lutomirski , X86 ML Cc: Borislav Petkov , linux-kernel@vger.kernel.org, "xen-devel@lists.xenproject.org" , Boris Ostrovsky , "H. Peter Anvin" References: <7c88ed36805d36841ab03ec3b48b4122c4418d71.1502164668.git.luto@kernel.org> From: Juergen Gross Message-ID: Date: Wed, 9 Aug 2017 17:39:12 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: <7c88ed36805d36841ab03ec3b48b4122c4418d71.1502164668.git.luto@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Language: de-DE Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 736 Lines: 22 On 08/08/17 05:59, Andy Lutomirski wrote: > Xen's raw SYSCALL entries are much less weird than native. Rather > than fudging them to look like native entries, use the Xen-provided > stack frame directly. > > This lets us eliminate entry_SYSCALL_64_after_swapgs and two uses of > the SWAPGS_UNSAFE_STACK paravirt hook. The SYSENTER code would > benefit from similar treatment. > > This makes one change to the native code path: the compat > instruction that clears the high 32 bits of %rax is moved slightly > later. I'd be surprised if this affects performance at all. > > Signed-off-by: Andy Lutomirski Reviewed-by: Juergen Gross Tested-by: Juergen Gross Thanks, Juergen