Re: [PATCH v2] arm: eBPF JIT compiler

From: Shubham Bansal
Date: Wed Jun 21 2017 - 10:26:52 EST

Hi Daniel,

> So my question would be, why can't the JIT imitate something
> similar to what we do in the interpreter as well? So looking
> at the disasm of what gcc compiles for the interpreter when it's
> doing the above call could help as well in going forward. Not
> sure if that answers your question, but perhaps not sure if I
> understand your question yet?

I just looked at the code again and I think I completely misunderstood
the logic of BPF_JMP | BPF_CALL.
I think each helper function is working like this.

____helper_function(u32 a1, u32 a2){

helper_function(u64 a1, u64 a2){
____helper_function((u32 *)a1, (u32 *)a2);

So ultimately, we call helper_function which takes u64 as arguments
only. I know its asking a lot, but can you please confirm this asap? I
would like to start implementing it.

> Cheers,
> Daniel