Spectre V1 diagnostic / mitigation

[Florian Weimer]

* Richard Biener:

> Sure, if we'd ever deploy this in production placing this in the
> TCB for glibc targets might be beneifical.  But as said the
> current implementation was just an experiment intended to be
> maximum portable.  I suppose the dynamic loader takes care
> of initializing the TCB data?

Yes, the dynamic linker will initialize it.  If you need 100% reliable
initialization with something that is not zero, it's going to be tricky
though.  Initial-exec TLS memory has this covered, but in the TCB, we
only have zeroed-out reservations today.

Thanks,
Florian