Messages in this thread | | | From | Shubham Bansal <> | Date | Sat, 17 Jun 2017 17:53:07 +0530 | Subject | Re: [PATCH v2] arm: eBPF JIT compiler |
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Hi Daniel,
> > Not all of the helpers have 4 or less byte arguments only, there are a > few with 8 byte arguments, so making that general assumption wouldn't > work. I guess what could be done is that helpers have a flag in struct > bpf_func_proto which indicates for JITs that all args are 4 byte on 32bit > so you could probably use convention similar to case2 for them. Presumably > for that information to process, the JIT might need to be reworked to > extract that via bpf_analyzer() that does a verifier run to re-analyze > the program like in nfp JIT case.
Let me try a better solution which can be used to support both 4 byte and 8 byte arguments. I hope it would work out. Are you sure this patch can pass if it only supports 4 byte arguments though? Let me list out what I have to do, so that you can tell me if I am thinking in a wrong way :-
* I will add a bit flag in bpf_func_proto to represent whether different arguments in a function call are 4 bytes or 8 bytes. If lsb of bit flag is set then first argument is 8 byte, otherwise its not. I think I can handle this flag properly in build_insn() in my code. Does this sound okay?
I don't understand second part of your solution, i.e.
> Presumably > for that information to process, the JIT might need to be reworked to > extract that via bpf_analyzer() that does a verifier run to re-analyze > the program like in nfp JIT case.
Please explain what are you suggesting and how can I extract bit flag from bpf_func_proto().
Please reply asap, as I would like to finish it over the weekend. Please.
-Shubham
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