On Tue, Aug 30, 2016 at 10:22:46PM +0200, Jakub Kicinski wrote: > On Tue, 30 Aug 2016 21:07:50 +0200, Daniel Borkmann wrote: > > > Having two modes seems more straight forward and I think we would only > > > need to pay attention in the LD_IMM64 case, I don't think I've seen > > > LLVM generating XORs, it's just the cBPF -> eBPF conversion. > > > > Okay, though, I think that the cBPF to eBPF migration wouldn't even > > pass through the bpf_parse() handling, since verifier is not aware on > > some of their aspects such as emitting calls directly (w/o *proto) or > > arg mappings. Probably make sense to reject these (bpf_prog_was_classic()) > > if they cannot be handled anyway? > > TBH again I only use cBPF for testing. It's a convenient way of > generating certain instruction sequences. I can probably just drop > it completely but the XOR patch is just 3 lines of code so not a huge > cost either... I'll keep patch 6 in my tree for now.
if xor matching is only need for classic, I would drop that patch just to avoid unnecessary state collection. The number of lines is not a concern, but extra state for state prunning is. > Alternatively - is there any eBPF assembler out there? Something > converting verifier output back into ELF would be quite cool. would certainly be nice. I don't think there is anything standalone. btw llvm can be made to work as assembler only, but simple flex/bison is probably better.
