Subject: [PATCH v2 1/3] arm64: spin-table: handle unmapped cpu-release-addrs

From: [email-masked] (Will Deacon)
Date: Fri, 15 Aug 2014 13:53:24 +0100

On Fri, Aug 15, 2014 at 01:07:16PM +0100, Ard Biesheuvel wrote:
> On 15 August 2014 13:57, Will Deacon <[email-masked]> wrote:
> > On Thu, Aug 14, 2014 at 07:10:13PM +0100, Ard Biesheuvel wrote:
> >> Patch 3/3 makes the EFI stub load Image at the lowest 2 meg boundary +
> >> TEXT_OFFSET instead of erroring out when base of DRAM + TEXT_OFFSET is
> >> occupied. This is necessary as the randomized TEXT_OFFSET could
> >> potentially conflict with reserved areas at the base of DRAM if a low
> >> value happens to be chosen.
> >>
> >> Patch 1/3 fixes the resulting breakage on APM Mustang in bringing up
> >> the secondaries, as on that board in particular, the reserved area at
> >> the base of DRAM contains the holding pen, and loading Image higher up
> >> makes the mailbox inaccessible through the linear mapping hence the
> >> need for ioremap_cache()
> >>
> >> Patch 2/3 is also a fix for a potential issue on UEFI boot, but it is
> >> unrelated to 1/3 and 3/3
> >
> > I was planning to take all of these for 3.18 as there's no regression here
> > (the fuzzing is a new debug feature and defaults to `n'). Do you think these
> > qualify as -rc1 material?
> >
> 
> Considering that TEXT_OFFSET fuzzing is recommended to be turned on
> for distro kernels, I would say this is definitely appropriate for
> 3.17

Whilst I see that in the commit log, the same recommendation doesn't appear
in the Kconfig text and I'm not sure that it's such a wise thing to say
either. From a distribution's point of view, I think I'd want any kernel
issues to be as reproducible as possible, and fuzzing the text offset seems
to go against that.

Will