[PATCH 6/7] mm/x86: Add missing pud helpers

[Peter Xu]

On Fri, Jun 21, 2024 at 07:36:30PM +0000, Edgecombe, Rick P wrote:
> On Fri, 2024-06-21 at 07:51 -0700, Dave Hansen wrote:
> > 
> > But, still, what if you take a Dirty=1,Write=1 pud and pud_modify() it
> > to make it Dirty=1,Write=0?  What prevents that from being
> > misinterpreted by the hardware as being a valid 1G shadow stack mapping?
> 
> Hmm, it looks like we could use an arch_check_zapped_pud() that does a warning
> like arch_check_zapped_pte/pmd() too. Not that we had no use for one before
> this.

I can definitely look into that, but this check only happens when zapping,
and IIUC it means there can still be outliers floating around.  I wonder
whether it should rely on page_table_check_pxx_set() from that regard.

Thanks,

-- 
Peter Xu