s390x help needed - kernel read faults

[Mark Wielaard]

On Mon, Nov 07, 2011 at 10:03:19AM -0600, David Smith wrote:
> I'm not sure why we provided our own functions, that decision was made a
> long time ago.  If we can't look at the address and know whether it is a
> user space or kernel space address, then I don't see much choice than to
> break up our memory accesses and require the callers to know whether
> they are accessing kernel space or user space.

Yes, it seems not that hard to track fully, we mostly do know already.
The only place where it would be helpful to determine whether or not
a address is valid for either kernel or user space would be in the
unwinder. There we walk the stack and stop and/or switch from kernel
to user stack walking based on whether the PC address is a valid
kernel or user space address. Is there really no way to tell the
difference on s390x from kernel space?

Thanks,

Mark