From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754246AbbKWJrk (ORCPT ); Mon, 23 Nov 2015 04:47:40 -0500 Received: from mx2.suse.de ([195.135.220.15]:40449 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752012AbbKWJrh (ORCPT ); Mon, 23 Nov 2015 04:47:37 -0500 Date: Mon, 23 Nov 2015 10:47:34 +0100 (CET) From: Miroslav Benes To: Chris J Arges cc: live-patching@vger.kernel.org, linux-kernel@vger.kernel.org, jpoimboe@redhat.com, jikos@kernel.org, pmladek@suse.com, jeyu@redhat.com, Seth Jennings , Vojtech Pavlik Subject: Re: [PATCH 1/3 v8] livepatch: add old_sympos as disambiguator field to klp_func In-Reply-To: <1448040325-32498-2-git-send-email-chris.j.arges@canonical.com> Message-ID: References: <1447693391-10065-1-git-send-email-chris.j.arges@canonical.com> <1448040325-32498-1-git-send-email-chris.j.arges@canonical.com> <1448040325-32498-2-git-send-email-chris.j.arges@canonical.com> User-Agent: Alpine 2.00 (LNX 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 20 Nov 2015, Chris J Arges wrote: > Currently, patching objects with duplicate symbol names fail because the > creation of the sysfs function directory collides with the previous > attempt. Appending old_addr to the function name is problematic as it > reveals the address of the function being patch to a normal user. Using > the symbol's occurrence in kallsyms to postfix the function name in the > sysfs directory solves the issue of having consistent unique names and > ensuring that the address is not exposed to a normal user. > > In addition, using the symbol position as the user's method to disambiguate > symbols instead of addr allows for disambiguating symbols in modules as > well for both function addresses and for relocs. This also simplifies much > of the code. Special handling for kASLR is no longer needed and can be > removed. The klp_find_verify_func_addr function can be replaced by > klp_find_object_symbol, and klp_verify_vmlinux_symbol and its callback can > be removed completely. > > In cases of duplicate symbols, old_sympos will be used to disambiguate > instead of old_addr. By default old_sympos will be 0, and patching will > only succeed if the symbol is unique. Specifying a positive value will > ensure that occurrence of the symbol in kallsyms for the patched object > will be used for patching if it is valid. > > In addition, make old_addr an internal structure field not to be specified > by the user. Finally, remove klp_find_verify_func_addr as it can be > replaced by klp_find_object_symbol directly. > > Support for symbol position disambiguation for relocations is added in the > next patch in this series. > > Signed-off-by: Chris J Arges Reviewed-by: Miroslav Benes Miroslav