Kexec on arm64

[geoff@infradead.org (Geoff Levand)]

Hi,

On Thu, 2014-07-24 at 10:36 +0100, Mark Rutland wrote:
> On Thu, Jul 24, 2014 at 01:38:07AM +0100, Geoff Levand wrote:
 
> > All memory management for the main cpu is done by the arch code.  Kexec
> > and cpu hot plug only work with the secondary cpus, so the problem would
> > be in the arch memory code, either in setup_restart() for shutdown, or
> > in the startup code.
> 
> It's possible that soft_restart and setup_restart are a little dodgy, as
> they also rely on the compiler being smart and not touching the stack
> after setup_restart().
> 
> However, they provide absolutely no guarantee that any data has been
> flushed out to the PoC [1]. If you require any data to be flushed out to the
> PoC so as to be visible to noncacheable accesses, you will need to
> ensure that this is flushed by VA before soft_restart is called. Data
> may have migrated to another cache (e.g. another CPU, or the L3) where
> it is not visible.

OK, kexec's reset routine relocate_new_kernel does use a few global
variables that are set by the main kexec routines.  I added a call to
__flush_dcache_area(), which uses 'dc civac' for those.

I had thought the call to __flush_dcache_all, which uses 'dc cisw', in
flush_cache_all() would be enough.

Arun, I also fixed UP builds.  Could you pull my latest and try with L3
enabled?

-Geoff