Re: Spectre

[maya%netbsd.org@localhost]

On Thu, Jan 18, 2018 at 12:37:11AM +0000, coypu%sdf.org@localhost wrote:
> - Variant 1 seems possible to avoid with low cost. It will likely result
>   in an error somewhere along the line, which is detectable. Flushing
>   the entire cache on userret will make it hard to exploit. Do all
>   bound checks failing result in an easily noticed error?

On further thought, this won't be sufficient protection.
It only protects assuming we:
- Cache memory
- Time access to memory
- Flush cache
- Time access to now cached memory

Flushing on userret/kernel entry is not sufficient because I am assuming
it will need a second trip to userland. it does not, assuming we can
construct our own perfect gadget.