From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752898AbbBYHXe (ORCPT ); Wed, 25 Feb 2015 02:23:34 -0500 Received: from mail-wg0-f50.google.com ([74.125.82.50]:41646 "EHLO mail-wg0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752440AbbBYHXd (ORCPT ); Wed, 25 Feb 2015 02:23:33 -0500 Date: Wed, 25 Feb 2015 08:23:28 +0100 From: Ingo Molnar To: Andy Lutomirski Cc: x86@kernel.org, linux-kernel@vger.kernel.org, Denys Vlasenko , Borislav Petkov Subject: Re: [PATCH 1/3] x86_64, entry: Remove a bogus ret_from_fork optimization Message-ID: <20150225072328.GB13061@gmail.com> References: <1b78c9e7b89e1c9481cd096fe57c2fb653eb9679.1424822291.git.luto@amacapital.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1b78c9e7b89e1c9481cd096fe57c2fb653eb9679.1424822291.git.luto@amacapital.net> 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 * Andy Lutomirski wrote: > ret_from_fork checks TIF_IA32 to determine whether pt_regs and the > related state make sense for ret_from_sys_call. This is entirely > the wrong check. TS_COMPAT would make a little more sense, but > there's really no point in keeping this optimization at all. > > This fixes a return to the wrong user CS if we came from int 0x80 in > a 64-bit task. > > Signed-off-by: Andy Lutomirski Acked-by: Ingo Molnar Thanks, Ingo