Messages in this thread Patch in this message | | | Date | Thu, 12 Nov 2015 19:47:30 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH 2/6] x86/mm/pageattr: Do not strip pte flags from cpa->pfn |
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On Thu, Nov 12, 2015 at 03:40:19PM +0000, Matt Fleming wrote: > Removing the PAGE_NX bit from cpa->pfn will corrupt the page frame > number address rather than removing PAGE_NX as the code intends. This > is unlikley to be a problem in practice because _PAGE_BIT_NX is bit 63 > and most machines do not have page frame numbers that reach that high. > > Still, pte flags are never stored in cpa->pfn so we can safely delete > the code. > > Cc: Borislav Petkov <bp@alien8.de> > Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com> > Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk> > --- > arch/x86/mm/pageattr.c | 5 ----- > 1 file changed, 5 deletions(-) > > diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c > index 893921b12272..d5240be55915 100644 > --- a/arch/x86/mm/pageattr.c > +++ b/arch/x86/mm/pageattr.c > @@ -885,11 +885,6 @@ static void populate_pte(struct cpa_data *cpa, > pte = pte_offset_kernel(pmd, start); > > while (num_pages-- && start < end) { > - > - /* deal with the NX bit */ > - if (!(pgprot_val(pgprot) & _PAGE_NX)) > - cpa->pfn &= ~_PAGE_NX; > - > set_pte(pte, pfn_pte(cpa->pfn, pgprot)); > > start += PAGE_SIZE; > --
I think this should be part of the 1st patch because there you're correcting ->pfn to actually be a pfn.
-- Regards/Gruss, Boris.
ECO tip #101: Trim your mails when you reply.
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