On 9/30/20 2:36 PM, Jarkko Sakkinen wrote: > 1. Full reptoline is the safest alternative and we have it done already. I wouldn't feel _quite_ comfortable saying this. LFENCEs have architecturally defined behavior. Retpolines have zero future guarantees in the architecture. I'll take an LFENCE that (versus a retpoline) is: 1. Less code 2. Never has to be patched 3. Never causes functional problems (like with CET) 4. Has architectural semantics The only advantage retpolines offer is that they have a well-defined mitigations on existing microarchitectures. To me, an LFENCE is waaaaaaay "safer".
