On Mon, Mar 3, 2014 at 2:05 AM, Hagen Paul Pfeifer <ha...@jauu.net> wrote: > * 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.
I'm still planning to bring benefits of ebpf-JIT to nft. There are different ways to approach it. I'm not ready to debate details, since I don't have a working code for nft+bpf yet and code speaks better than words. But I'm confident that ebpf instruction set will not need 128-bit extensions. If something unforeseen is needed, we can always add it. Right now I'm testing ebpf+seccomp. As a micro benchmark I took a test from libseccomp and added dummy syscall loop. There is a nice speedup. will post a patch soon. Thanks Alexei -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
