Re: [PATCH v3 18/37] mm: Add guard pages around a shadow stack.

Edgecombe, Rick P
2022-11-15T21:50:05Z

On Tue, 2022-11-15 at 21:56 +0100, Peter Zijlstra wrote:
> On Tue, Nov 15, 2022 at 08:40:19PM +0000, Edgecombe, Rick P wrote:
> > > > +unsigned long __weak stack_guard_start_gap(struct
> > > > vm_area_struct
> > > > *vma)
> > > > +{
> > > > + if (vma->vm_flags & VM_GROWSDOWN)
> > > > + return stack_guard_gap;
> > > > + return 0;
> > > > +}
> > >
> > > I'm thinking perhaps this wants to be an inline function?
> >
> > I don't think it can work with weak then.
>
> That was kinda the point, __weak sucks and this is very small in any
> case.

__weak was suggested here:

https://lore.kernel.org/lkml/f92c5110-7d97-b68d-d387-7e6a16a29e49@intel.com/

Let me try to put in cross arch code again like the other suggestion
was. I can't remember the reason why I didn't do it.