Messages in this thread | | | Date | Tue, 20 Feb 2018 01:22:14 -0700 | From | "Jan Beulich" <> | Subject | Re: [PATCH RESEND] x86: consider effective protection attributes in W+X check |
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>>> On 20.02.18 at 09:10, <mingo@kernel.org> wrote: > * Jan Beulich <JBeulich@suse.com> wrote: >> Using just the leaf page table entry flags would cause a false warning >> in case _PAGE_RW is clear or _PAGE_NX is set in a higher level entry. > > Under what circumstances did you see false positive warnings?
As explained in the 2-patch series this was originally part of, there continues to be that W+X warning when running under Xen, as commit 2cc42bac1c ("x86-64/Xen: eliminate W+X mappings") has to make the necessary adjustment in L2 rather than L1 (the reason is explained there). I.e. _PAGE_RW is clear there in L1, but _PAGE_NX is set in L2.
>> Hand through both the current entry's flags as well as the accumulated >> effective value (the latter as pgprotval_t instead of pgprot_t, as it's >> not an actual entry's value). >> >> Signed-off-by: Jan Beulich <jbeulich@suse.com> >> Reviewed-by: Juergen Gross <jgross@suse.com> >> --- >> arch/x86/mm/dump_pagetables.c | 92 ++++++++++++++++++++++++++---------------- >> 1 file changed, 57 insertions(+), 35 deletions(-) > > Could you please rebase this on top of latest tip:master, which changed > arch/x86/mm/dump_pagetables.c non-trivially due the dynamic 5 level paging > changes?
I'll see what I can do; it's a pity that the change here, which had been sent weeks ago and is a bug fix, hadn't gone in before that other change (being more an improvement than a bug fix). At least it doesn't look like the re-basing would be very difficult.
Jan
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