From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Marek Subject: Re: [PATCH] x86/kbuild: enable modversions for symbols exported from asm Date: Thu, 1 Dec 2016 17:12:41 +0100 Message-ID: <6e8cf20b-2d2f-ba1f-e02c-c757d5a25db7@suse.com> References: <20161129131922.GA31466@angband.pl> <20161129135118.24696-1-kilobyte@angband.pl> <30bb2db4-47bd-0c35-8328-ef032b551f06@suse.com> <20161129195721.GI2697@decadent.org.uk> <20161201051852.28dc335f@roar.ozlabs.ibm.com> <1480541581.16599.78.camel@decadent.org.uk> <20161201125545.406d092c@roar.ozlabs.ibm.com> <1480559754.16599.92.camel@decadent.org.uk> <20161201143928.07a08348@roar.ozlabs.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: Received: from mx2.suse.de ([195.135.220.15]:49951 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752008AbcLAQMp (ORCPT ); Thu, 1 Dec 2016 11:12:45 -0500 In-Reply-To: <20161201143928.07a08348@roar.ozlabs.ibm.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Nicholas Piggin , Ben Hutchings Cc: Linus Torvalds , Adam Borowski , Greg Kroah-Hartman , Linux Kbuild mailing list , Debian kernel maintainers , "linux-arch@vger.kernel.org" , Arnd Bergmann , Ingo Molnar , Linux Kernel Mailing List , Dodji Seketeli On 2016-12-01 04:39, Nicholas Piggin wrote: > On Thu, 01 Dec 2016 02:35:54 +0000 > Ben Hutchings wrote: >> As I understand it, genksyms incorporates the definitions of a >> function's parameter and return types - not just their names - and all >> the types they refer to, recursively. So a structure size change >> should change the version of all functions where the function and its >> caller pass that structure between them, however indirectly. It finds >> such indirect ABI breakage for me fairly regularly, though of course I >> don't know that it finds everything. > > It is only the type name. > > Not only that but even if you did extend it further to structure type > arrangement then you still have to deal with other structures followed > via pointers. Or (rarer but not unheard of): > > - changes to structures without changes of the types of their members > - changes to arguments without changes of their type This is already covered by genksyms. Try make V=1 with CONFIG_MODVERSIONS=y and add the -D option to one of the genksyms command. I wanted to paste the expanded signature for register_filesystem() as an example, but vger would probably drop the mail for being too big :). > - changes to semantics of functions > - data structures derived in ways other than exported symbols, e.g., > fixed register for `current` on some archs Right, this is something that genksyms has no idea about. Michal