From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752129AbeC2OmN (ORCPT ); Thu, 29 Mar 2018 10:42:13 -0400 Received: from isilmar-4.linta.de ([136.243.71.142]:44430 "EHLO isilmar-4.linta.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750732AbeC2OmL (ORCPT ); Thu, 29 Mar 2018 10:42:11 -0400 Date: Thu, 29 Mar 2018 16:42:09 +0200 From: Dominik Brodowski To: Matthew Wilcox Cc: linux-kernel@vger.kernel.org, viro@ZenIV.linux.org.uk, torvalds@linux-foundation.org, arnd@arndb.de, linux-arch@vger.kernel.org, hmclauchlan@fb.com, tautschn@amazon.co.uk, Amir Goldstein , Andi Kleen , Andrew Morton , Christoph Hellwig , Darren Hart , "David S . Miller" , "Eric W . Biederman" , "H . Peter Anvin" , Ingo Molnar , Jaswinder Singh , Jeff Dike , Jiri Slaby , kexec@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-s390@vger.kernel.org, "Luis R . Rodriguez" , netdev@vger.kernel.org, Peter Zijlstra , Thomas Gleixner , user-mode-linux-devel@lists.sourceforge.net, x86@kernel.org Subject: Re: [PATCH 000/109] remove in-kernel calls to syscalls Message-ID: <20180329144209.GA25559@isilmar-4.linta.de> References: <20180329112426.23043-1-linux@dominikbrodowski.net> <20180329142027.GA24860@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180329142027.GA24860@bombadil.infradead.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 On Thu, Mar 29, 2018 at 07:20:27AM -0700, Matthew Wilcox wrote: > On Thu, Mar 29, 2018 at 01:22:37PM +0200, Dominik Brodowski wrote: > > At least on 64-bit x86, it will likely be a hard requirement from v4.17 > > onwards to not call system call functions in the kernel: It is better to > > use use a different calling convention for system calls there, where > > struct pt_regs is decoded on-the-fly in a syscall wrapper which then hands > > processing over to the actual syscall function. This means that only those > > parameters which are actually needed for a specific syscall are passed on > > during syscall entry, instead of filling in six CPU registers with random > > user space content all the time (which may cause serious trouble down the > > call chain).[*] > > How do we stop new ones from springing up? Some kind of linker trick > like was used to, er, "dissuade" people from using gets()? Once the patches which modify the syscall calling convention are merged, it won't compile on 64-bit x86, but bark loudly. That should frighten anyone. Meow. Thanks, Dominik From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dominik Brodowski Subject: Re: [PATCH 000/109] remove in-kernel calls to syscalls Date: Thu, 29 Mar 2018 16:42:09 +0200 Message-ID: <20180329144209.GA25559@isilmar-4.linta.de> References: <20180329112426.23043-1-linux@dominikbrodowski.net> <20180329142027.GA24860@bombadil.infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-kernel@vger.kernel.org, viro@ZenIV.linux.org.uk, torvalds@linux-foundation.org, arnd@arndb.de, linux-arch@vger.kernel.org, hmclauchlan@fb.com, tautschn@amazon.co.uk, Amir Goldstein , Andi Kleen , Andrew Morton , Christoph Hellwig , Darren Hart , "David S . Miller" , "Eric W . Biederman" , "H . Peter Anvin" , Ingo Molnar , Jaswinder Singh , Jeff Dike , Jiri Slaby , kexec@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-s390@vger.kernel.org, "Luis R . Rodriguez" , netdev@vg To: Matthew Wilcox Return-path: Content-Disposition: inline In-Reply-To: <20180329142027.GA24860@bombadil.infradead.org> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Thu, Mar 29, 2018 at 07:20:27AM -0700, Matthew Wilcox wrote: > On Thu, Mar 29, 2018 at 01:22:37PM +0200, Dominik Brodowski wrote: > > At least on 64-bit x86, it will likely be a hard requirement from v4.17 > > onwards to not call system call functions in the kernel: It is better to > > use use a different calling convention for system calls there, where > > struct pt_regs is decoded on-the-fly in a syscall wrapper which then hands > > processing over to the actual syscall function. This means that only those > > parameters which are actually needed for a specific syscall are passed on > > during syscall entry, instead of filling in six CPU registers with random > > user space content all the time (which may cause serious trouble down the > > call chain).[*] > > How do we stop new ones from springing up? Some kind of linker trick > like was used to, er, "dissuade" people from using gets()? Once the patches which modify the syscall calling convention are merged, it won't compile on 64-bit x86, but bark loudly. That should frighten anyone. Meow. Thanks, Dominik From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from isilmar-4.linta.de ([136.243.71.142]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1f1Ykw-00029N-Dl for kexec@lists.infradead.org; Thu, 29 Mar 2018 14:42:24 +0000 Date: Thu, 29 Mar 2018 16:42:09 +0200 From: Dominik Brodowski Subject: Re: [PATCH 000/109] remove in-kernel calls to syscalls Message-ID: <20180329144209.GA25559@isilmar-4.linta.de> References: <20180329112426.23043-1-linux@dominikbrodowski.net> <20180329142027.GA24860@bombadil.infradead.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20180329142027.GA24860@bombadil.infradead.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Matthew Wilcox Cc: Peter Zijlstra , Amir Goldstein , linux-mm@kvack.org, "H . Peter Anvin" , tautschn@amazon.co.uk, Ingo Molnar , linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, Andi Kleen , user-mode-linux-devel@lists.sourceforge.net, x86@kernel.org, hmclauchlan@fb.com, Christoph Hellwig , Jiri Slaby , Darren Hart , Jaswinder Singh , arnd@arndb.de, Jeff Dike , viro@ZenIV.linux.org.uk, Thomas Gleixner , netdev@vger.kernel.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, "Luis R . Rodriguez" , "Eric W . Biederman" , linux-fsdevel@vger.kernel.org, Andrew Morton , torvalds@linux-foundation.org, "David S . Miller" On Thu, Mar 29, 2018 at 07:20:27AM -0700, Matthew Wilcox wrote: > On Thu, Mar 29, 2018 at 01:22:37PM +0200, Dominik Brodowski wrote: > > At least on 64-bit x86, it will likely be a hard requirement from v4.17 > > onwards to not call system call functions in the kernel: It is better to > > use use a different calling convention for system calls there, where > > struct pt_regs is decoded on-the-fly in a syscall wrapper which then hands > > processing over to the actual syscall function. This means that only those > > parameters which are actually needed for a specific syscall are passed on > > during syscall entry, instead of filling in six CPU registers with random > > user space content all the time (which may cause serious trouble down the > > call chain).[*] > > How do we stop new ones from springing up? Some kind of linker trick > like was used to, er, "dissuade" people from using gets()? Once the patches which modify the syscall calling convention are merged, it won't compile on 64-bit x86, but bark loudly. That should frighten anyone. Meow. Thanks, Dominik _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec