On Fri, Feb 09, 2007 at 05:34:16PM +0100, Franck Bui-Huu wrote:
> Date: Fri, 9 Feb 2007 17:34:16 +0100
> From: "Franck Bui-Huu" <fbuihuu@xxxxxxxxx>
> To: "Atsushi Nemoto" <anemo@xxxxxxxxxxxxx>
> Subject: Re: [PATCH 3/3] signal.c: fix gcc warning on 32 bits kernel
> Cc: vagabon.xyz@xxxxxxxxx, ralf@xxxxxxxxxxxxxx,
> linux-mips@xxxxxxxxxxxxxx
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> On 2/9/07, Atsushi Nemoto <anemo@xxxxxxxxxxxxx> wrote:
> >On Fri, 9 Feb 2007 16:07:38 +0100, Franck Bui-Huu <vagabon.xyz@xxxxxxxxx>
> >wrote:
> >> new_ka.sa.sa_handler = (__sighandler_t) __gu_tmp;
> >>
> >> Here we try to cast an 'unsigned long long' into a 32 bits pointer and
> >> that's the reason of the warning.
> >
> >This line is never executed on 32bit kernel and gcc optimize out. On
>
> yes I agree but it seems that gcc compiles this line before optimizing
> out...
>
> >
> >I think this is a problem of __get_user() implementation or gcc
> >itself. Though I can not find better solution yet, hacking the caller
> >to avoid the warning would not be right things to to.
>
> I agree too but I haven't found something else.
All gcc versions produce this warning and no, it's not a gcc bug but a
kernel bug. __get_user expands into:
case 8: {
unsigned long long __gu_tmp;
[...]
new_ka.sa.sa_handler =
(__typeof__(*((&act->sa_handler)))) __gu_tmp;
}
Which is quite a funny C problem to solve :-)
Ralf
