From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755481AbeARQJy (ORCPT ); Thu, 18 Jan 2018 11:09:54 -0500 Received: from bombadil.infradead.org ([65.50.211.133]:58183 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755287AbeARQJw (ORCPT ); Thu, 18 Jan 2018 11:09:52 -0500 Date: Thu, 18 Jan 2018 16:46:07 +0100 From: Peter Zijlstra To: Thomas Gleixner Cc: LKML , x86@kernel.org, Borislav Petkov , David Woodhouse Subject: Re: [PATCH] x86/mce: Make machine check speculation protected Message-ID: <20180118154607.GN2228@hirez.programming.kicks-ass.net> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 18, 2018 at 04:28:26PM +0100, Thomas Gleixner wrote: > The machine check idtentry uses an indirect branch directly from the low > level code. This evades the speculation protection. > > Replace it by a direct call into C code and issue the indirect call there > so the compiler can apply the proper speculation protection. > > Signed-off-by: Thomas Gleixner > --- > arch/x86/entry/entry_64.S | 2 +- > arch/x86/include/asm/traps.h | 1 + > arch/x86/kernel/cpu/mcheck/mce.c | 5 +++++ > 3 files changed, 7 insertions(+), 1 deletion(-) > > --- a/arch/x86/entry/entry_64.S > +++ b/arch/x86/entry/entry_64.S > @@ -1264,7 +1264,7 @@ idtentry async_page_fault do_async_page_ > #endif > > #ifdef CONFIG_X86_MCE > -idtentry machine_check has_error_code=0 paranoid=1 do_sym=*machine_check_vector(%rip) > +idtentry machine_check do_mce has_error_code=0 paranoid=1 Nice, Thanks!