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

[Mark Salter]

On Fri, 2014-08-15 at 15:28 +0200, Ard Biesheuvel wrote:
> On 15 August 2014 14:53, Will Deacon <will.deacon at arm.com> wrote:
> > On Fri, Aug 15, 2014 at 01:07:16PM +0100, Ard Biesheuvel wrote:
> >> On 15 August 2014 13:57, Will Deacon <will.deacon at arm.com> 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.
> >
> 
> OK. There is one other real world issue that 3/3 addresses, which are
> platforms that have memreserves at the base of DRAM containing bits of
> UEFI itself (this is what got this whole discussion going in the first
> place). Currently, we cannot boot via UEFI on these platforms, as the
> EFI stub will only consider base of DRAM + TEXT_OFFSET as an option,
> and fail the boot if it is not available.
> 
> If this is something that could wait until 3.18 as well (Mark S?),
> then it's fine by me.
> 

I don't see a problem with waiting until 3.18.