Re: [patch 00/38] x86/retbleed: Call depth tracking mitigation

[Joao Moreira]

> The problem with this is that the cmpl instruction contains the full
> type hash, which means that any instruction that's FIXED_OFFSET from
> the cmpl is a valid indirect call target as far as KCFI is concerned.
> -6 was chosen specifically to make the ud2 the only possible target.

Ugh. The bitter truth. I'll think a bit further.