Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753339AbbL2MZM (ORCPT ); Tue, 29 Dec 2015 07:25:12 -0500 Received: from smtp48.i.mail.ru ([94.100.177.108]:53175 "EHLO smtp48.i.mail.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752049AbbL2MZJ (ORCPT ); Tue, 29 Dec 2015 07:25:09 -0500 Subject: Re: [PATCH v2 1/4] x86/signal/64: Add a comment about sigcontext->fs and gs To: Andy Lutomirski References: <66cb936904b7ce56ddc1ce58119bd9683e4f3b43.1445822498.git.luto@kernel.org> <5634DD68.4090709@list.ru> Cc: Denys Vlasenko , Borislav Petkov , Brian Gerst , "linux-kernel@vger.kernel.org" , X86 ML , Linus Torvalds From: Stas Sergeev Message-ID: <56827B97.9060106@list.ru> Date: Tue, 29 Dec 2015 15:24:55 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Mras: Ok Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1415 Lines: 31 08.12.2015 02:23, Andy Lutomirski пишет: > On Oct 31, 2015 8:25 AM, "Stas Sergeev" wrote: >> >> 26.10.2015 04:25, Andy Lutomirski пишет: >> >>> These fields have a strange history. This tries to document it. >>> >>> This borrows from 9a036b93a344 ("x86/signal/64: Remove 'fs' and 'gs' >>> from sigcontext"), which was reverted by ed596cde9425 ("Revert x86 >>> sigcontext cleanups"). >>> >>> Signed-off-by: Andy Lutomirski >> >> Now the strategy about SS is to always save it to the sigcontext. >> This is good because the syscall can clobber it, so the app had >> to be very careful in the past trying to save it by hands. >> How about saving also fs and gs? (without restoring yet) >> If you do, you'll save dosemu a headache of doing any "pre-syscall" >> work. Pre-syscall work is very nasty. >> I haven't checked if the syscall clobber also these or only SS, >> but perhaps saving them by the kernel won't hurt? > > There's a bunch of ongoing work about FS and GS. I want to wait and see. Andy, have you postponed only this, or also the sigreturn patch? Long time no news... sigreturn patch would really be nice to have. -- 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/