powerpc/mm: Fixup kernel read only mapping

[Michael Ellerman]

On Thu, 2016-11-24 at 09:39:54 UTC, "Aneesh Kumar K.V" wrote:
> With commit e58e87adc8bf9 ("powerpc/mm: Update _PAGE_KERNEL_RO") we started
> using the ppp value 0b110 to map kernel readonly. But that facility
> was only added as part of ISA 2.04. For earlier ISA version only supported ppp
> bit value for readonly mapping is 0b011. (This implies both user and kernel
> get mapped using the same ppp bit value for readonly mapping.).
> 
> Update the code such that for earlier architecture version we use ppp value
> 0b011 for readonly mapping. We don't differentiate between power5+ and power5
> here and apply the new ppp bits only from power6 (ISA 2.05). This keep the
> changes minimal.
> 
> This fixes issue with PS3 spu usage reported at
> https://lkml.kernel.org/r/rep.1421449714.geoff@infradead.org
> 
> Fixes: e58e87adc8bf9 ("powerpc/mm: Update _PAGE_KERNEL_RO")
> Tested-by: Geoff Levand <geoff at infradead.org>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar at linux.vnet.ibm.com>

Applied to powerpc fixes, thanks.

https://git.kernel.org/powerpc/c/984d7a1ec67ce3a46324fa4bcb4c74

cheers