* Daniel Borkmann | 2014-03-01 01:30:00 [+0100]: >>>as in 'struct bpf_insn' the immediate value is 32 bit, so for 64 bit >>>comparisons, you'd still need to load to immediate values, right? >> >>there is no insn that use 64-bit immediate, since 64-bit immediates >>are extremely rare. grep x86-64 asm code for movabsq will return very few. >>llvm or gcc can easily construct any constant by combination of mov, >>shifts and ors. >>bpf64 comparisons are all 64-bit right now. So far I didn't see a need to do >>32-bit comparison, since old bpf is all unsigned, mapping 32->64 of >>Jxx is painless. > >Hm, fair enough, I was just thinking for comparisons of IPv6 addresses >when we do socket filtering. On the other hand, old and new insns are >both 64 bit wide and can be used though the same api then.
What about the long term idea to support JITed nftables? A 128 bit immediate is required - maybe the biggest requirement for nftable support. Hagen -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
