[RFC] Attempt to clean up sigsuspend et al

[Paul Mackerras]

David Woodhouse writes:

> This is an attempt to get rid of it all, motivated mostly because I want
> to add two _new_ functions which would need such treatment (pselect,
> ppoll).
> 
> We define a new thread flag TIF_RESTOREALL which is set by the syscall
> which needs this treatment, and make the syscall return path honour it.
> This seems to work as far as I've tested it (i.e. the system boots) for
> ppc64, but I haven't even attempted to compile the 32-bit version yet.

Ummm, I don't see where you save the non-volatile GPRs to the
exception frame _before_ do_signal (called from within *_sigsuspend)
copies them to the user stack...

Paul.