Re: [PATCH 0/2] Fix W+X debug feature on x86

[Steven Price]

On 21/05/2020 20:08, Andrew Morton wrote:
> On Thu, 21 May 2020 16:23:06 +0100 Steven Price <steven.price@xxxxxxx> wrote:
>
> > Jan alert me[1] that the W+X detection debug feature was broken in x86
> > by my change[2] to switch x86 to use the generic ptdump infrastructure.
> >
> > Fundamentally the approach of trying to move the calculation of
> > effective permissions into note_page() was broken because note_page() is
> > only called for 'leaf' entries and the effective permissions are passed
> > down via the internal nodes of the page tree. The solution I've taken
> > here is to create a new (optional) callback which is called for all
> > nodes of the page tree and therefore can calculate the effective
> > permissions.
> >
> > Secondly on some configurations (32 bit with PAE) "unsigned long" is not
> > large enough to store the table entries. The fix here is simple - let's
> > just use a u64.
>
> I assumed that a cc:stable was appropriate on both of these(?).

Yes thanks.

> > I'd welcome testing (and other comments), especially if you have a
> > configuration which previously triggered W+X warnings as I don't have
> > such a setup.
>
> I'll wait a while for such testing.  If nothing happens then I guess we
> merge it up and see what then happens.

Thanks,

Steve