From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from verein.lst.de ([213.95.11.211]:51513 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728501AbgIHGbg (ORCPT ); Tue, 8 Sep 2020 02:31:36 -0400 Date: Tue, 8 Sep 2020 08:31:33 +0200 From: Christoph Hellwig Subject: set_fs removal for s390 Message-ID: <20200908063133.GA14217@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: linux-s390-owner@vger.kernel.org List-ID: To: Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Harald Freudenberger Cc: linux-s390@vger.kernel.org Hi s390 maintainers, the base work to remove address space overrides using set_fs() has landed in linux-next through this tree: https://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git/log/?h=base.set_fs and in addition to x86 and powerpc converted there, we have arm, arm64 and RISC-V conversion in progress. That means s390 is the only "tier 1" architecture still missing. Due to the special instructions for accessing the user space address space I don't really feel like doing the conversion myself, but it would be great if we could get s390 done for 5.10 as well. The rought TODO list is: (1) actually stop using set_fs in the zrcypt driver. I could prepare a crude untested patch for that if it helps. (2) implement the __get_user_nofault and __put_user_nofault helpers to safely access kernel memory. These should behave like get_user/put_user under set_fs(KERNEL_DS), but not actually manipulate any task state to do so (3) unselect CONFIG_SET_FS and remove all the code related to overriding the address space(3) unselect CONFIG_SET_FS and remove all the code related to overriding the address space limit