Re: [patch 00/11] x86/vdso: Cleanups, simmplifications and CLOCK_TAI support

[Thomas Gleixner]

On Fri, 14 Sep 2018, Florian Weimer wrote:

> On 09/14/2018 02:50 PM, Thomas Gleixner wrote:
> > Matt attempted to add CLOCK_TAI support to the VDSO clock_gettime()
> > implementation, which extended the clockid switch case and added yet
> > another slightly different copy of the same code.
> > 
> > Especially the extended switch case is problematic as the compiler tends to
> > generate a jump table which then requires to use retpolines.
> 
> Does vDSO code really have to use retpolines?  It's in userspace, after all.

Unless you have IBRS/STIPB enabled, you need user space ratpoutine as well.

Thanks,

	tglx