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

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Message-ID: <fed5a4d4249d2387cc02a169f89c65753a6303ff.camel@intel.com>
Date:   Tue, 15 Nov 2022 21:49:50 +0000
From:   "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
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Subject: Re: [PATCH v3 18/37] mm: Add guard pages around a shadow stack.

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.