The performance implications of #Spectre mitigations will come back to haunt us. The “clean” solution of using the indirect branch prediction barrier (IBPB) costs 5-10k cycles.
https://lkml.org/lkml/2018/1/21/93
So naturally people will try to come up with clever solutions like “an ELF flag that says I am spectre-safe”.
https://lkml.org/lkml/2018/1/21/35
@yomimono Dealing with the fallout will not be fun for a long time :/ Its like a tax that everybody has to pay in many different ways and for the foreseeable future.