Facing issue with va to pa conversion in arm64/makedumpfile

[Bhupesh Sharma]

Hello Akshay,

As Kazu mentioned please try the patch :
http://lists.infradead.org/pipermail/kexec/2020-September/021336.html
and let me know your observations.

I am still on my holidays but will try to check my emails from today,
so will help you with any further issues.

Thanks,
Bhupesh

On Thu, Nov 19, 2020 at 5:56 AM HAGIO KAZUHITO(萩尾　一仁)
<k-hagio-ab at nec.com> wrote:
>
> Hi Akshay,
> (Cc Bhupesh)
>
> -----Original Message-----
> > Hi Pratyush/ Kazuhito ,
> >
> > While attempting to create dumpfile on arm64, I was face issues with
> > virtual address to physical address conversion when kalsr is enable.
> > Linux kernel version is 5.4.42 stable kernel.
>
> It seems that it would be due to the flipped VA space at 5.4 arm64 kernel.
> Bhupesh has been addressing this for us, but not merged yet.
> How does it work with this patch?
> http://lists.infradead.org/pipermail/kexec/2020-September/021336.html
>
> (Its 1/3 and 2/3 patches were already merged, so I think the 3/3 patch
> can be applied on top of the latest makedumpfile.)
>
> Thanks,
> Kazu
>
> >
> > The following patch seems to add patch to enable kalsr support :
> >
> > [PATCH 10/10] arm64: fix memory layout as per changes in v4.6 kernel
> >
> > https://sourceforge.net/p/makedumpfile/code/ci/b6fe70c7ffef9affb540412407702b15d4a196e9
> >
> >
> > static unsigned long long
> > +__pa(unsigned long vaddr)
> > +{
> > +       if (kimage_voffset == NOT_FOUND_NUMBER ||
> > +                       (vaddr >= PAGE_OFFSET))
> > +               return (vaddr - PAGE_OFFSET + info->phys_base);
> > +       else
> > +               return (vaddr - kimage_voffset);
> > +}
> >
> >
> > I see that even when kimage_voffset is available , it calculates pa
> > using PAGE_OFFSET.
> > But as KALSR is enabled it should ideally use kimage_voffset.
> >
> > Not sure what is the significance of the check (vaddr >= PAGE_OFFSET) if
> > kimage_voffset is available.
> >
> > i think this should be something like
> >
> > +       if (kimage_voffset == NOT_FOUND_NUMBER) && (vaddr >=
> > PAGE_OFFSET))
> > +               return (vaddr - PAGE_OFFSET + info->phys_base);
> > +       else
> > +               return (vaddr - kimage_voffset);
> >
> >
> >
> > Because we want to check vaddr is greater than PAGE_OFFSET when we are
> > considering linear mapping without kaslr seed.
> >
> > Or may be we should have a separate check which will error out all vaddr
> > less than PAGE_OFFSET and kimage_voffset.
> >
> > +       if  (vaddr < PAGE_OFFSET)
> > +              return -EINVAL;
> > +       if (kimage_voffset == NOT_FOUND_NUMBER)
> > +               return (vaddr - PAGE_OFFSET + info->phys_base);
> > +       else
> > +               return (vaddr - kimage_voffset);
> >
> > --
> > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora
> > Forum,
> > a Linux Foundation Collaborative Project
> >
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>