Re: [tip: x86/bugs] x86/retpoline: Ensure default return thunk isn't used at runtime

[Josh Poimboeuf]

On Wed, Oct 18, 2023 at 05:12:45PM +0200, Borislav Petkov wrote:
> On Wed, Oct 18, 2023 at 03:38:56PM +0200, Ingo Molnar wrote:
> > If then WARN_ONCE().
> 
> WARN_ONCE() is not enough considering that if this fires, it means we're
> not really properly protected against one of those RET-speculation
> things.
> 
> It needs to be warning constantly but then still allow booting. I.e,
> a ratelimited warn of sorts but I don't think we have that... yet.

I'm not sure a rate-limited WARN() would be a good thing.  Either the
user is regularly checking dmesg (most likely in some automated fashion)
or they're not.  If the latter, a rate-limited WARN() would wrap dmesg
pretty quickly.

-- 
Josh