Re: your "x86: mm: convert dump_pagetables to use walk_page_range" change

From: Peter Zijlstra
Date: Tue May 12 2020 - 09:19:22 EST


On Tue, May 12, 2020 at 02:02:51PM +0100, Steven Price wrote:
> > Additionally I'd like to note that note_page()'s "unsigned long val"
> > parameter isn't wide enough for 32-bit PAE PTEs, and hence the NX
> > flag will always be seen as clear in new_prot in such configs.
>
> Ah, interesting. I'm not sure what type is actually guaranteed to be
> correct. pgprotval_t is x86 specific, but it might be necessary to extend it
> to other architectures. I think I got the "unsigned long" from the generic
> page.h (and because it happens to work on most architectures) - but hadn't
> noticed that that file was specifically only for NOMMU architectures.

unsigned long long should cover the i386-PAE / ARMv7-LPAE cases. I
can't, from teh top of my head, remember if there's anybody else who has
a longer PTE.