Re: [PATCH 2/7] signal: factor copy_siginfo_to_external32 from copy_siginfo_to_user32

[Christophe Leroy]

Le 28/04/2020 Ã 09:09, Christoph Hellwig a ÃcritÂ:
> On Mon, Apr 27, 2020 at 03:40:50PM -0700, Andrew Morton wrote:
> > > https://www.spinics.net/lists/kernel/msg3473847.html
> > > https://www.spinics.net/lists/kernel/msg3473840.html
> > > https://www.spinics.net/lists/kernel/msg3473843.html
> >
> > OK, but that doesn't necessitate the above monstrosity?  How about
> >
> > static int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
> > 			     const struct kernel_siginfo *from, bool x32_ABI)
> > {
> > 	struct compat_siginfo new;
> > 	copy_siginfo_to_external32(&new, from);
> > 	...
> > }
> >
> > int copy_siginfo_to_user32(struct compat_siginfo __user *to,
> > 			   const struct kernel_siginfo *from)
> > {
> > #if defined(CONFIG_X86_X32_ABI) || defined(CONFIG_IA32_EMULATION)
> > 	return __copy_siginfo_to_user32(to, from, in_x32_syscall());
> > #else
> > 	return __copy_siginfo_to_user32(to, from, 0);
> > #endif
> > }
> >
> > Or something like that - I didn't try very hard.  We know how to do
> > this stuff, and surely this thing isn't how!
>
> I guess that might be a worthwhile middle ground.  Still not a fan of
> all these ifdefs..

Can't we move the small X32 specific part out of 
__copy_siginfo_to_user32(), in an arch specific helper that voids for 
other architectures ?

Something like:

		if (!arch_special_something(&new, from)) {
			new.si_utime = from->si_utime;
			new.si_stime = from->si_stime;
		}

Then the arch_special_something() does what it wants in x86 and returns 
1, and for architectures not implementating it, a generic version return 
0 all the time.

Christophe