Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932374AbbKQTiv (ORCPT ); Tue, 17 Nov 2015 14:38:51 -0500 Received: from aserp1040.oracle.com ([141.146.126.69]:36586 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932245AbbKQTiu (ORCPT ); Tue, 17 Nov 2015 14:38:50 -0500 Subject: Re: [Xen-devel] [PATCH] xen/x86: Adjust stack pointer in xen_sysexit To: Andy Lutomirski , Andrew Cooper References: <1447456706-24347-1-git-send-email-boris.ostrovsky@oracle.com> <56468D24.8030801@oracle.com> <564A0371.2040104@oracle.com> <20151116195906.GB20137@pd.tnic> <20151116202232.GC20137@pd.tnic> <564A50C3.1000200@zytor.com> <564B3C57.5000002@oracle.com> <564B7C2B.5030901@citrix.com> <564B81DE.90909@oracle.com> Cc: "linux-kernel@vger.kernel.org" , xen-devel , Borislav Petkov , David Vrabel , "H. Peter Anvin" From: Boris Ostrovsky Message-ID: <564B8234.4000004@oracle.com> Date: Tue, 17 Nov 2015 14:38:28 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 MIME-Version: 1.0 In-Reply-To: <564B81DE.90909@oracle.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Source-IP: userv0021.oracle.com [156.151.31.71] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 774 Lines: 18 On 11/17/2015 02:37 PM, Boris Ostrovsky wrote: > On 11/17/2015 02:16 PM, Andy Lutomirski wrote: >>>> Looks good to me. Does Xen have any sysexit/sysret32 equivalent to >>>> return to 32-bit user mode? If so, it could be worth trying to wire >>>> it up by patching the jz instead of the test instruction. > > We can actually make patching a little bit more efficient by replacing > the test instruction with 'xor %eax,%eax'. That way we won't need any > 'nop's. Nevermind that, we are looking at flags, not register. -boris -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/