[PATCH v2 3/3] efi: x86: Wire up IBT annotation in memory attributes table

[Peter Zijlstra]

On Wed, Feb 08, 2023 at 07:17:15AM -0800, Dave Hansen wrote:
> On 2/6/23 04:49, Ard Biesheuvel wrote:
> > --- a/arch/x86/kernel/apm_32.c
> > +++ b/arch/x86/kernel/apm_32.c
> > @@ -609,7 +609,7 @@ static long __apm_bios_call(void *_call)
> >  
> >  	apm_irq_save(flags);
> >  	firmware_restrict_branch_speculation_start();
> > -	ibt = ibt_save();
> > +	ibt = ibt_save(true);
> 
> My only nit with these is the bare use of 'true'/'false'.  It's
> impossible to tell at the call-site what the 'true' means.  So, if you
> happen to respin these and see a nice way to remedy this I'd appreciate it.

I've often wished for a named argument extention to C, much like named
initializers, such that one can write:

	ibt_save(.disable = true);

Because the thing you mention is very common with boolean arguments, the
what gets lost in the argument name and true/false just isn't very
telling.

But yeah, even if by some miracle all compiler guys were like, YES! and
implemented it tomorrow, we couldn't use it for a good few years anyway
:-/