From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753211AbbESIPl (ORCPT ); Tue, 19 May 2015 04:15:41 -0400 Received: from www.linutronix.de ([62.245.132.108]:53093 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751280AbbESIPj (ORCPT ); Tue, 19 May 2015 04:15:39 -0400 Date: Tue, 19 May 2015 10:15:46 +0200 (CEST) From: Thomas Gleixner To: Dave Hansen cc: linux-kernel@vger.kernel.org, x86@kernel.org, dave.hansen@linux.intel.com, oleg@redhat.com, bp@alien8.de, riel@redhat.com, sbsiddha@gmail.com, luto@amacapital.net, mingo@redhat.com, hpa@zytor.com, fenghua.yu@intel.com Subject: Re: [PATCH 02/19] x86, fpu: Wrap get_xsave_addr() to make it safer In-Reply-To: <20150519062529.9636B111@viggo.jf.intel.com> Message-ID: References: <20150519062528.E2D5DDFF@viggo.jf.intel.com> <20150519062529.9636B111@viggo.jf.intel.com> User-Agent: Alpine 2.11 (DEB 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001,URIBL_BLOCKED=0.001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 18 May 2015, Dave Hansen wrote: > From: Dave Hansen > > The MPX code appears to be saving off the FPU in an unsafe > way. It does not disable preemption or ensure that the > FPU state has been allocated. All of the preemption safety > comes from the unfortunatley-named 'unlazy_fpu()'. > > This patch introduces a new helper which will do both of > those things internally. > > Note that this requires a patch from Oleg in order to work > properly. It is currently in tip/x86/fpu. > > > commit f893959b0898bd876673adbeb6798bdf25c034d7 > > Author: Oleg Nesterov > > Date: Fri Mar 13 18:30:30 2015 +0100 > > > > x86/fpu: Don't abuse drop_init_fpu() in flush_thread() > > Signed-off-by: Dave Hansen > Cc: Oleg Nesterov > Cc: bp@alien8.de > Cc: Rik van Riel > Cc: Suresh Siddha > Cc: Andy Lutomirski > Cc: Thomas Gleixner > Cc: Ingo Molnar > Cc: "H. Peter Anvin" > Cc: Fenghua Yu > Cc: the arch/x86 maintainers Reviewed-by: Thomas Gleixner