Messages in this thread | | | Date | Fri, 4 Sep 2015 10:58:31 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH] x86/headers: Fix (old) header file dependency bug in uapi/asm/sigcontext32.h |
| |
* Mikko Rapeli <mikko.rapeli@iki.fi> wrote:
> On Thu, Sep 03, 2015 at 09:42:32AM +0200, Ingo Molnar wrote: > > > > * Mikko Rapeli <mikko.rapeli@iki.fi> 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 <asm/sigcontext.h> > > #include <asm/sigcontext32.h> > > > > If you only include sigcontext32.h: > > > > #include <asm/sigcontext32.h> > > > > 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?
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.
Thanks,
Ingo
| |