Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753360AbbGBK0C (ORCPT ); Thu, 2 Jul 2015 06:26:02 -0400 Received: from mail.skyhub.de ([78.46.96.112]:33261 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752472AbbGBKZo (ORCPT ); Thu, 2 Jul 2015 06:25:44 -0400 Date: Thu, 2 Jul 2015 12:25:20 +0200 From: Borislav Petkov To: Andy Lutomirski Cc: x86@kernel.org, linux-kernel@vger.kernel.org, =?utf-8?B?RnLDqWTDqXJpYw==?= Weisbecker , Rik van Riel , Oleg Nesterov , Denys Vlasenko , Kees Cook , Brian Gerst , paulmck@linux.vnet.ibm.com Subject: Re: [PATCH v4 10/17] x86/entry/64: Really create an error-entry-from-usermode code path Message-ID: <20150702102520.GE4001@pd.tnic> References: <88b8446ce3af6822db02b5f983b8740f8365e9b4.1435602481.git.luto@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <88b8446ce3af6822db02b5f983b8740f8365e9b4.1435602481.git.luto@kernel.org> 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 Content-Length: 1939 Lines: 58 On Mon, Jun 29, 2015 at 12:33:42PM -0700, Andy Lutomirski wrote: > In 539f51136500 ("x86/asm/entry/64: Disentangle error_entry/exit > gsbase/ebx/usermode code"), I arranged the code slightly wrong -- > IRET faults would skip the code path that was intended to execute on > all error entries from user mode. Fix it up. > > This does not fix a bug, but we'll need it, and it slightly shrinks > the code. > > Signed-off-by: Andy Lutomirski > --- > arch/x86/entry/entry_64.S | 12 ++++++++---- > 1 file changed, 8 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S > index 141a5d49dddc..cd9cbc62159c 100644 > --- a/arch/x86/entry/entry_64.S > +++ b/arch/x86/entry/entry_64.S > @@ -1145,9 +1145,14 @@ ENTRY(error_entry) > testb $3, CS+8(%rsp) > jz error_kernelspace > > - /* We entered from user mode */ > +error_entry_from_usermode_swapgs: > + /* > + * We entered from user mode or we're pretending to have entered > + * from user mode due to an IRET fault. > + */ > SWAPGS > > +error_entry_from_usermode_after_swapgs: > error_entry_done: Why the second label? Also, please make all those labels local by prefixing them with .L because they appear unnecesasrily in objdump output as global symbols. $ objdump -d vmlinux | grep -E "^[0-9a-f]+ <(error_entry_\w*|error_kernelspace|bstep_iret|error_bad_iret)" ffffffff8167a4a8 : ffffffff8167a4ab : ffffffff8167a4b1 : ffffffff8167a4e0 : ffffffff8167a4e8 : Oh, and shorter please :) -- Regards/Gruss, Boris. ECO tip #101: Trim your mails when you reply. -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/