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SubjectRe: [PATCH v2 1/5] x86/mm/pageattr: Ensure cpa->pfn only contains page frame numbers
On Mon, 16 Nov, at 07:56:17AM, Dave Hansen wrote:
> I'm glad you're looking at this. It obviously needed some love. :)
>
> On 11/14/2015 02:00 PM, Matt Fleming wrote:
> > + npages = (_end - _text) >> PAGE_SHIFT;
> > + text = __pa(_text);
> > + pfn = text >> PAGE_SHIFT;
> > +
> > + if (kernel_map_pages_in_pgd(pgd, pfn, text, npages, 0)) {
> > + pr_err("Failed to map kernel text 1:1\n");
> > + return 1;
> > + }
>
> Are _end and _text guaranteed to be aligned? If not, I think the
> calculation might be wrong. Just for fun, imagine that _end=0xfff and
> _text=0x1001. npages would be 0.

Bugger. Good catch, thanks.

> Some other code like set_kernel_text_rw() does alignment on _text.
>
> One nit is that there's quite a bit going on here, like rearranging the
> phys_stack arithmetic ordering that is far beyond just simplifying the
> paddr vs. pfn issue, but that isn't called out in the changelog at all.

Yeah, the phys_stack hunk actually slipped into this patch by
accident. It ensures the stack is mapped into the EFI page tables.
I'll split this out.

> Your fixes all look correct to me, fwiw.

Thanks! If you could respond to the next version with an ACK or
Reviewed-by tag, that'd be great.


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