From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758800AbbIDMSl (ORCPT ); Fri, 4 Sep 2015 08:18:41 -0400 Received: from mail.kapsi.fi ([217.30.184.167]:52688 "EHLO mail.kapsi.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752335AbbIDMSj (ORCPT ); Fri, 4 Sep 2015 08:18:39 -0400 Date: Fri, 4 Sep 2015 15:18:27 +0300 From: Mikko Rapeli To: Ingo Molnar Cc: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, linux-kernel@vger.kernel.org, Linus Torvalds , Borislav Petkov , Andy Lutomirski Subject: Re: [PATCH] x86/headers: Fix (old) header file dependency bug in uapi/asm/sigcontext32.h Message-ID: <20150904121827.GB9187@lakka.kapsi.fi> References: <1433000370-19509-1-git-send-email-mikko.rapeli@iki.fi> <1433000370-19509-95-git-send-email-mikko.rapeli@iki.fi> <20150902193453.GZ9187@lakka.kapsi.fi> <20150903074231.GA23098@gmail.com> <20150904071031.GA9187@lakka.kapsi.fi> <20150904085831.GA17456@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20150904085831.GA17456@gmail.com> X-SA-Exim-Connect-IP: 2001:1bc8:1004::1 X-SA-Exim-Mail-From: mikko.rapeli@iki.fi X-SA-Exim-Scanned: No (on mail.kapsi.fi); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 04, 2015 at 10:58:31AM +0200, Ingo Molnar wrote: > > * Mikko Rapeli wrote: > > > On Thu, Sep 03, 2015 at 09:42:32AM +0200, Ingo Molnar wrote: > > > > > > * Mikko Rapeli wrote: > > > > > > > Hi Ingo, Thomas and Peter, > > > > > > > > Do you have any pointers for me how arch/x86/include/uapi/asm/sigcontext32.h > > > > could be fixed to also compile in userspace? Is definition of _fpx_sw_bytes > > > > or _fpstate_ia32 even needed there? > > > > > > > > Instructions to reproduce the userspace build failure are here: > > > > https://lkml.org/lkml/2015/5/30/98 > > > > > > Yeah, so this is a real bug in the headers, good find. > > > > > > Also note that somewhat luckily your testcase is artificial, no real user-space > > > code can contain that code at the moment because the header never built standalone > > > in the past either AFAICS. > > > > > > So it's an old header file dependency bug, to make it build in user-space you need > > > to do this workaround: > > > > > > #include > > > #include > > > > > > If you only include sigcontext32.h: > > > > > > #include > > > > > > it will fail to build. > > > > > > To fix the bug: > > > > > > > > --- a/arch/x86/include/uapi/asm/sigcontext32.h > > > > > +++ b/arch/x86/include/uapi/asm/sigcontext32.h > > > > > @@ -45,7 +45,6 @@ struct _fpstate_ia32 { > > > > > __u32 padding[44]; > > > > > union { > > > > > __u32 padding2[12]; > > > > > - struct _fpx_sw_bytes sw_reserved; > > > > > }; > > > > > }; > > > > > > No, those fields are real and compat sigframe handling user-space might be relying > > > on them. > > > > > > Does the fix below work for you? > > > > Unfortunately no: > > > > cc -Wall -c -nostdinc -I /usr/lib/gcc/i586-linux-gnu/5/include -I /usr/lib/gcc/i > > 586-linux-gnu/5/include-fixed -I . -I ../headers_compile_test_include -I ../head > > ers_compile_test_include/i586-linux-gnu ./asm/sigcontext32.c > > In file included from ./asm/sigcontext32.c:1:0: > > ./asm/sigcontext32.h:12:8: error: redefinition of ‘struct _fpreg’ > > struct _fpreg { > > ^ > > In file included from ./asm/sigcontext32.h:6:0, > > from ./asm/sigcontext32.c:1: > > ./asm/sigcontext.h:56:8: note: originally defined here > > struct _fpreg { > > ^ > > In file included from ./asm/sigcontext32.c:1:0: > > ./asm/sigcontext32.h:17:8: error: redefinition of ‘struct _fpxreg’ > > struct _fpxreg { > > ^ > > In file included from ./asm/sigcontext32.h:6:0, > > from ./asm/sigcontext32.c:1: > > ./asm/sigcontext.h:61:8: note: originally defined here > > struct _fpxreg { > > ^ > > In file included from ./asm/sigcontext32.c:1:0: > > ./asm/sigcontext32.h:23:8: error: redefinition of ‘struct _xmmreg’ > > struct _xmmreg { > > ^ > > In file included from ./asm/sigcontext32.h:6:0, > > from ./asm/sigcontext32.c:1: > > ./asm/sigcontext.h:67:8: note: originally defined here > > struct _xmmreg { > > ^ > > FAILED: ./asm/sigcontext32.h > > > > I guess this was the reason why I ended with the hack. > > sigcontext32.h is a 64-bit only header (for compat functionality), and you are > trying to build this on i386, right? Yes, i386 32bit. > In theory we could unify them mostly, the two structures match mostly, except that > '_fpstate_ia32::padding' is named 'padding1' in _fpstate, and there's also some > legacy uglies wrt. user-space sigcontext definitions. > > So this either gets cleaned up properly, with the legacy hacks/wrappers clearly > isolated, or we could state that you shouldn't build 64-bit headers in 32-bit > environments. Should the sigcontext32.h have some 32bit ifdefs maybe? I assume that the exported header files should be the same for both 64 and 32 bit i386/x86 -Mikko