properly support exec and wait with kernel pointers

[Arnd Bergmann]

On Mon, Jun 15, 2020 at 3:00 PM Christoph Hellwig <hch at lst.de> wrote:
>
> Hi all,
>
> this series first cleans up the exec code and then adds proper
> kernel_execveat and kernel_wait callers instead of relying on the fact
> that the early init code and kernel threads implicitly run with
> the address limit set to KERNEL_DS.
>
> Note that the cleanup removes the compat execve(at) handlers (almost)
> entirely, as we can handle the compat difference very nicely in a
> unified codebase.  The only exception is x86 where this would list the
> handlers twice in the same syscall table due to the messed up x32
> design.  I had to add an extra compat handler just for that case, but
> maybe someone has a better idea.

I looked at all the patches and I like it a lot. I replied with some suggestions
for x32, but maybe I misunderstood what its problem is, as I don't see
anything preventing us from having two entries in the x32 table pointing
to the same function.

       Arnd