From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752722AbdKWMAh (ORCPT ); Thu, 23 Nov 2017 07:00:37 -0500 Received: from mx2.suse.de ([195.135.220.15]:51761 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752500AbdKWMAg (ORCPT ); Thu, 23 Nov 2017 07:00:36 -0500 Date: Thu, 23 Nov 2017 13:00:31 +0100 From: Borislav Petkov To: Andy Lutomirski Cc: X86 ML , "linux-kernel@vger.kernel.org" , Brian Gerst , Dave Hansen , Linus Torvalds , Josh Poimboeuf Subject: Re: [PATCH v2 09/18] x86/asm: Move SYSENTER_stack to the beginning of struct tss_struct Message-ID: <20171123120031.dpgq7t7jc4n26sen@pd.tnic> References: <4195a4db127cbf769666e283f5dba551d29d5ef0.1511325444.git.luto@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <4195a4db127cbf769666e283f5dba551d29d5ef0.1511325444.git.luto@kernel.org> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 21, 2017 at 08:44:04PM -0800, Andy Lutomirski wrote: > I want SYSENTER_stack to have reliable overflow detection, which > means that it needs to be at the bottom of a page, not the top. Passive-impersonal tone pls. > Move it to the beginning of struct tss_struct and page-align it. > > Also add an assertion to make sure that the fixed hardware TSS > doesn't cross a page boundary. > > Signed-off-by: Andy Lutomirski > --- > arch/x86/include/asm/processor.h | 21 ++++++++++++--------- > arch/x86/kernel/cpu/common.c | 22 ++++++++++++++++++++++ > 2 files changed, 34 insertions(+), 9 deletions(-) > > diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h > index d32a3c88a968..8f5dac9dfbdc 100644 > --- a/arch/x86/include/asm/processor.h > +++ b/arch/x86/include/asm/processor.h > @@ -327,7 +327,16 @@ struct x86_hw_tss { > > struct tss_struct { > /* > - * The hardware state: > + * Space for the temporary SYSENTER stack, used for SYSENTER > + * and the entry trampoline as well. > + */ > + unsigned long SYSENTER_stack_canary; > + unsigned long SYSENTER_stack[64]; > + > + /* > + * The fixed hardware portion. This must not cross a page boundary > + * at risk of violating the SDM's advice and potentially triggering > + * errata. > */ > struct x86_hw_tss x86_tss; > > @@ -338,15 +347,9 @@ struct tss_struct { > * be within the limit. > */ > unsigned long io_bitmap[IO_BITMAP_LONGS + 1]; > +} __attribute__((__aligned__(PAGE_SIZE))); WARNING: __aligned(size) is preferred over __attribute__((aligned(size))) #58: FILE: arch/x86/include/asm/processor.h:350: +} __attribute__((__aligned__(PAGE_SIZE))); -- Regards/Gruss, Boris. SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg) --