Re: [PATCH v2 37/59] x86/putuser: Provide room for padding

[Linus Torvalds]

So I don't hate this patch and it's probably good for consistency, but
I really think that the retbleed tracking could perhaps be improved to
let this be all unnecessary.

The whole return stack depth counting is already not 100% exact, and I
think we could just make the rule be that we don't track leaf
functions.

Why? It's just a off-by-one in the already not exact tracking. And -
perhaps equally importantly - leaf functions are very very common
dynamically, and I suspect it's trivial to see them.

Yes, yes, you could make objtool even smarter and actually do some
kind of function flow graph thing (and I think some people were
talking about that with the whole ret counting long long ago), but the
leaf function thing is the really simple low-hanging fruit case of
that.

            Linus