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SubjectRe: [PATCH v9 00/21] Generic page walk and ptdump
On Wed, Jul 24, 2019 at 03:57:33PM +0200, Thomas Gleixner wrote:
> On Wed, 24 Jul 2019, Steven Price wrote:
> > On 23/07/2019 11:16, Mark Rutland wrote:
> > > Are there any visible changes to the arm64 output?
> >
> > arm64 output shouldn't change. I've confirmed that "efi_page_tables" is
> > identical on a Juno before/after the change. "kernel_page_tables"
> > obviously will vary depending on the exact layout of memory, but the
> > format isn't changed.
> >
> > x86 output does change due to patch 14. In this case the change is
> > removing the lines from the output of the form...
> >
> > > 0xffffffff84800000-0xffffffffa0000000 440M pmd
> >
> > ...which are unpopulated areas of the memory map. Populated lines which
> > have attributes are unchanged.
>
> Having the hole size and the level in the dump is a very conveniant thing.

Mhmm; I thought that we logged which level was empty on arm64 (but
apparently not), since knowing the structure can be important.

> Right now we have:
>
> 0xffffffffc0427000-0xffffffffc042b000 16K ro NX pte
> 0xffffffffc042b000-0xffffffffc042e000 12K RW NX pte
> 0xffffffffc042e000-0xffffffffc042f000 4K pte
> 0xffffffffc042f000-0xffffffffc0430000 4K ro x pte
> 0xffffffffc0430000-0xffffffffc0431000 4K ro NX pte
> 0xffffffffc0431000-0xffffffffc0433000 8K RW NX pte
> 0xffffffffc0433000-0xffffffffc0434000 4K pte
> 0xffffffffc0434000-0xffffffffc0436000 8K ro x pte
> 0xffffffffc0436000-0xffffffffc0438000 8K ro NX pte
> 0xffffffffc0438000-0xffffffffc043a000 8K RW NX pte
> 0xffffffffc043a000-0xffffffffc043f000 20K pte
> 0xffffffffc043f000-0xffffffffc0444000 20K ro x pte
> 0xffffffffc0444000-0xffffffffc0447000 12K ro NX pte
> 0xffffffffc0447000-0xffffffffc0449000 8K RW NX pte
> 0xffffffffc0449000-0xffffffffc044f000 24K pte
> 0xffffffffc044f000-0xffffffffc0450000 4K ro x pte
> 0xffffffffc0450000-0xffffffffc0451000 4K ro NX pte
> 0xffffffffc0451000-0xffffffffc0453000 8K RW NX pte
> 0xffffffffc0453000-0xffffffffc0458000 20K pte
> 0xffffffffc0458000-0xffffffffc0459000 4K ro x pte
> 0xffffffffc0459000-0xffffffffc045b000 8K ro NX pte
>
> with your change this becomes:
>
> 0xffffffffc0427000-0xffffffffc042b000 16K ro NX pte
> 0xffffffffc042b000-0xffffffffc042e000 12K RW NX pte
> 0xffffffffc042f000-0xffffffffc0430000 4K ro x pte
> 0xffffffffc0430000-0xffffffffc0431000 4K ro NX pte
> 0xffffffffc0431000-0xffffffffc0433000 8K RW NX pte
> 0xffffffffc0434000-0xffffffffc0436000 8K ro x pte
> 0xffffffffc0436000-0xffffffffc0438000 8K ro NX pte
> 0xffffffffc0438000-0xffffffffc043a000 8K RW NX pte
> 0xffffffffc043f000-0xffffffffc0444000 20K ro x pte
> 0xffffffffc0444000-0xffffffffc0447000 12K ro NX pte
> 0xffffffffc0447000-0xffffffffc0449000 8K RW NX pte
> 0xffffffffc044f000-0xffffffffc0450000 4K ro x pte
> 0xffffffffc0450000-0xffffffffc0451000 4K ro NX pte
> 0xffffffffc0451000-0xffffffffc0453000 8K RW NX pte
> 0xffffffffc0458000-0xffffffffc0459000 4K ro x pte
> 0xffffffffc0459000-0xffffffffc045b000 8K ro NX pte
>
> which is 5 lines less, but a pain to figure out the size of the holes. And
> it becomes even more painful when the holes go across different mapping
> levels.

I agree.

Steven, could you align arm64 with the x86 behaviour here?

Thanks,
Mark.

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