From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932219AbcEBWWK (ORCPT ); Mon, 2 May 2016 18:22:10 -0400 Received: from mga09.intel.com ([134.134.136.24]:47418 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755166AbcEBWWF (ORCPT ); Mon, 2 May 2016 18:22:05 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.24,569,1455004800"; d="scan'208";a="95911005" Date: Mon, 2 May 2016 15:17:54 -0700 From: Yu-cheng Yu To: Dave Hansen Cc: x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, Andy Lutomirski , Borislav Petkov , Sai Praneeth Prakhya , "Ravi V. Shankar" , Fenghua Yu Subject: Re: [PATCH v4 04/10] x86/xsaves: Introduce a new check that allows correct xstates copy from kernel to user directly Message-ID: <20160502221754.GA22667@test-lenovo> References: <5723FE20.7000906@linux.intel.com> <20160502155734.GA21577@test-lenovo> <57277B11.9080802@linux.intel.com> <20160502163410.GA21734@test-lenovo> <572783C3.8040907@linux.intel.com> <20160502171936.GA22224@test-lenovo> <57278F56.6050600@linux.intel.com> <20160502211817.GA22492@test-lenovo> <20160502212449.GA22532@test-lenovo> <5727C75E.8000401@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5727C75E.8000401@linux.intel.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, May 02, 2016 at 02:32:14PM -0700, Dave Hansen wrote: > > I think we're off in the weeds here. > > Please just send an updated patch for what you want to do here. >>From 43134a773d23ae8bab9f158d143c5cfb76bc0e9c Mon Sep 17 00:00:00 2001 From: Yu-cheng Yu Date: Sat, 14 Nov 2015 16:59:45 -0800 Subject: [PATCH] x86/xsaves: Introduce a new check that allows correct xstates copy from kernel to user directly XSAVES is a kernel instruction and uses a compacted format. When working with user space, the kernel should provide standard-format, non-supervisor state data. We cannot do __copy_to_user() from a compacted- format kernel xstate area to a signal frame. Dave Hansen proposes this method to simplify copy xstate directly to user. Signed-off-by: Fenghua Yu Signed-off by: Yu-cheng Yu --- arch/x86/include/asm/fpu/xstate.h | 1 + arch/x86/kernel/fpu/signal.c | 3 ++- arch/x86/kernel/fpu/xstate.c | 2 +- 3 files changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h index 16df2c4..d812cf3 100644 --- a/arch/x86/include/asm/fpu/xstate.h +++ b/arch/x86/include/asm/fpu/xstate.h @@ -47,5 +47,6 @@ extern void update_regset_xstate_info(unsigned int size, u64 xstate_mask); void fpu__xstate_clear_all_cpu_caps(void); void *get_xsave_addr(struct xregs_state *xsave, int xstate); const void *get_xsave_field_ptr(int xstate_field); +int using_compacted_format(void); #endif diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c index 0fbf60c..d7fdd8c 100644 --- a/arch/x86/kernel/fpu/signal.c +++ b/arch/x86/kernel/fpu/signal.c @@ -8,6 +8,7 @@ #include #include #include +#include #include @@ -167,7 +168,7 @@ int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size) sizeof(struct user_i387_ia32_struct), NULL, (struct _fpstate_32 __user *) buf) ? -1 : 1; - if (fpregs_active()) { + if (fpregs_active() || using_compacted_format()) { /* Save the live register state to the user directly. */ if (copy_fpregs_to_sigframe(buf_fx)) return -1; diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 170c164..2b59bd7 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -415,7 +415,7 @@ static int xfeature_size(int xfeature_nr) * that it is obvious which aspect of 'XSAVES' is being handled * by the calling code. */ -static int using_compacted_format(void) +int using_compacted_format(void) { return cpu_has_xsaves; } -- 1.9.1