pkeys on POWER: Default AMR, UAMOR values

[Florian Weimer]

On 05/18/2018 09:39 PM, Andy Lutomirski wrote:
> The difference is that x86 starts out with deny-all instead of allow-all.
> The POWER semantics make it very hard for a multithreaded program to
> meaningfully use protection keys to prevent accidental access to important
> memory.

And you can change access rights for unallocated keys (unallocated at 
thread start time, allocated later) on x86.  I have extended the 
misc/tst-pkeys test to verify that, and it passes on x86, but not on 
POWER, where the access rights are stuck.

I believe this is due to an incorrect UAMOR setting.

Thanks,
Florian