RE: [PATCH] x86/entry/64: randomize kernel stack offset upon syscall

[Reshetova, Elena]

> From: Reshetova, Elena
> > Sent: 24 April 2019 12:43
> >
> > Sorry for the delay - Easter holidays + I was trying to arrange my brain around
> proposed options.
> > Here what I think our options are with regards to the source of randomness:
> >
> > 1) rdtsc or variations based on it (David proposed some CRC-based variants for
> example)
> 
> Do I remember something about rdtsc being made less accurate in order to
> make it (slightly) more difficult to use it to measure timing attacks?

Do you have any pointers on this? I did an online search, but could not find anything
concrete. The Intel manual doesn't talk about precision at all, only about protected
mode.

> 
> If true, and it applies to the kernel (eg in a VM) then this is probably
> all pointless!

You mean additional constructions on top of TSC is pointless? 

Best Regards,
Elena.