Re: [PATCH] mm: provide a fallback for PAGE_KERNEL_RO for architectures

Luis R. Rodriguez
2018-05-09T01:04:38Z

On Fri, Apr 27, 2018 at 08:18:10PM -0700, Matthew Wilcox wrote:
> On Fri, Apr 27, 2018 at 05:15:26PM -0700, Luis R. Rodriguez wrote:
> > Some architectures do not define PAGE_KERNEL_RO, best we can do
> > for them is to provide a fallback onto PAGE_KERNEL. Remove the
> > hack from the firmware loader and move it onto the asm-generic
> > header, and document while at it the affected architectures
> > which do not have a PAGE_KERNEL_RO:
> >
> > o alpha
> > o ia64
> > o m68k
> > o mips
> > o sparc64
> > o sparc
>
> ia64 doesn't have it?
>
> *fx: riffles through architecture book*
>
> That seems like an oversight of the Linux port. Tony, Fenghua, any thoughts?

Poke *Tony, Fenghua* ?

> (also, Luis, maybe move the PAGE_KERNEL_EXEC fallback the same way you
> moved the PAGE_KERNEL_RO fallback?)

Done. Will queue in the generic PAGE_KERNEL_EXEC patch to my series.

> --- >8 ---
>
> ia64: Add PAGE_KERNEL_RO and PAGE_KERNEL_EXEC
>
> The rest of the kernel was falling back to simple PAGE_KERNEL pages; using
> PAGE_KERNEL_RO and PAGE_KERNEL_EXEC provide better protection against
> unintended writes.
>
> Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>

Nice, should I queue this into my series as well?

Luis