RE: [RFC 09/10] x86/enter: Create macros to restrict/unrestrict Indirect Branch Speculation

[Van De Ven, Arjan]

> > you asked before and even before you sent the email I confirmed to
> > you that the document is correct
> >
> > I'm not sure what the point is to then question that again 15 minutes
> > later other than creating more noise.
> 
> Apologies, I hadn't seen the comment on IRC.
> 
> Sometimes the docs *don't* get it right, especially when they're
> released in a hurry as that one was. I note there's a *fourth* version
> of microcode-update-guidance.pdf available now, for example :)
> 
> So it is useful that you have explicitly stated that for *this*
> specific concern, the document is in fact correct that SMEP saves us
> from BTB and RSB pollution, *despite* the empirical evidence that those
> structures only hold the low 31 bits.

your question was specific to RSB not BTB. But please show the empirical evidence for RSB ?