From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759495AbcBYIZb (ORCPT ); Thu, 25 Feb 2016 03:25:31 -0500 Received: from mail-wm0-f67.google.com ([74.125.82.67]:33832 "EHLO mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753502AbcBYIZ3 (ORCPT ); Thu, 25 Feb 2016 03:25:29 -0500 Date: Thu, 25 Feb 2016 09:25:25 +0100 From: Ingo Molnar To: Stas Sergeev Cc: linux-kernel@vger.kernel.org, Andy Lutomirski , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, Borislav Petkov , Brian Gerst , Oleg Nesterov , Richard Weinberger , Stas Sergeev Subject: Re: [PATCH] [Cleanup] x86: signal: unify the sigaltstack check with other arches Message-ID: <20160225082524.GA12294@gmail.com> References: <1456095685-23857-1-git-send-email-stsp@list.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1456095685-23857-1-git-send-email-stsp@list.ru> 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 * Stas Sergeev wrote: > Currently x86's get_sigframe() checks for "current->sas_ss_size" > to determine whether there is a need to switch to sigaltstack. > The common practice used by all other arches is to check for > sas_ss_flags(sp) == 0 > > This patch makes the code consistent with other arches. > The slight complexity of the patch is added by the optimization on > !sigstack check that was requested by Andy Lutomirski: sas_ss_flags(sp)==0 > already implies that we are not on a sigstack, so the code is shuffled > to avoid the duplicate checking. So this changelog is missing an analysis about what effect this change will have on applications. Can any type of user-space code see a change in behavior? If yes, what will happen and is that effect desirable? Thanks, Ingo