On Wed, Sep 30, 2020 at 06:28:06PM +0300, Jarkko Sakkinen wrote: > On Wed, Sep 30, 2020 at 07:33:38AM -0700, Dave Hansen wrote: > > On 9/30/20 7:20 AM, Jarkko Sakkinen wrote: > > > I'm not expert on Spectre, or any sort of security researcher, but I've > > > read a few papers about and understand the general concept. With the > > > constraints how the callback is used in practice, I'd *guess* it is > > > fine to drop retpoline but I really need some feedback on this from > > > people who understand these attacks better. > > > > Do you recall why you added it in the first place? What was the > > motivation for it? Were you responding to a review comment? > > Absolutely cannot recall it :-) I even cannot recall the exact time when > we landed the vDSO in the first place. Too much stuff has happend during > the long three year upstreaming cycle. I will try to backtrack this > info. It originated in a comment from Andy when we were discussing the legitimacy of the callback. From that point on it got taken as gospel that the indirect call would be implemented as a retpoline. https://lkml.kernel.org/r/CALCETrVBR+2HjTqX=W4r9GOq69Xg36v4gmCKqK0wUjzAqBJnrw@xxxxxxxxxxxxxx
