On Thu, Dec 14, 2017 at 6:10 AM, Kirill A. Shutemov <[email protected]> wrote: > On Wed, Dec 13, 2017 at 09:01:50AM -0800, Andy Lutomirski wrote: >> On Wed, Dec 13, 2017 at 5:12 AM, Kirill A. Shutemov >> <[email protected]> wrote: >> > On Tue, Dec 12, 2017 at 07:56:38AM -0800, Andy Lutomirski wrote: >> >> The ESPFIX64 user mapping belongs in pti.c just like all the other >> >> user mappings. Move it there and make it work correctly while we're >> >> at it. >> >> >> >> Signed-off-by: Andy Lutomirski <[email protected]> >> > >> > Acked-by: Kirill A. Shutemov <[email protected]> >> > >> > BTW, why do we open-code p?d_alloc() in pti_user_pagetable_walk_*()? >> > It seems unnecessary and potentially bogus: see smp_wmb() in __p?d_alloc() >> > helpers. >> >> The helpers won't work -- we're allocating kernel-owned tables in the >> usermode part of init_mm. The p?d_alloc() helpers allocate >> user-accounted tables in the kernelmode part of the mm. > > What's wrong to account them against init_mm? >
Nothing. But the other parts are showstoppers: the helpers won't set _PAGE_USER in the higher level entries and they will put the pgds in the wrong place.
