UML for arm64

[Rob Herring]

On Thu, Jun 22, 2023 at 2:14 PM Benjamin Berg <benjamin at sipsolutions.net> wrote:
>
> Hi,
>
> On Thu, 2023-06-22 at 21:41 +0200, Johannes Berg wrote:
> > On Thu, 2023-06-22 at 13:22 -0600, Rob Herring wrote:
> > > I'm interested in getting UML working on Arm. Is anyone aware of any
> > > efforts to do this already?
> >
> > Not me ... But yeah, agree that it seems likely to require some
> > refactoring, even if _some_ degree of attempts were made to keep arch-
> > specific things there ...
> >
> > There might be a ton of arch-specific things in the ptrace code too
>
> At least a lot of the register handling, but that will always be
> somewhat architecture specific.
>
> > ... , so perhaps it'd be easier to start with the seccomp-based model:
> >
> > https://patchwork.ozlabs.org/project/linux-um/list/?series=329466
> >
> > But that's not really done yet either.
>
> Yes, though I have quite some updates locally that solve the security
> issues (i.e. prevent host syscalls from userspace). So, it does need
> rebasing and I am sure bugfixes, but I think it is getting into a
> pretty good shape overall.
>
> Either way, the old patchset will give you a good idea about how it all
> works, the changes are mostly in the details. I am happy to push out a
> new version sooner rather than later if it might help with any efforts
> on your side.

>From a quick scan, it looks like there's some cleanups in the series
which would be helpful without seccomp parts. One of the initial
issues I've found is UML using older ptrace interfaces which arm64
doesn't implement. PTRACE_GETREGS for example.

Rob