[PATCH] arm64: bpf: Fix branch offset in JIT

[Xi Wang]

On Mon, Sep 14, 2020 at 10:55 AM Ilias Apalodimas
<ilias.apalodimas at linaro.org> wrote:
> We've briefly discussed this approach with Yauheni while coming up with the
> posted patch.
> I think that contructing the array correctly in the first place is better.
> Right now it might only be used in bpf2a64_offset() and bpf_prog_fill_jited_linfo()
> but if we fixup the values on the fly in there, everyone that intends to use the
> offset for any reason will have to account for the missing instruction.

I don't understand what you mean by "correctly."  What's your correctness spec?

I don't think there's some consistent semantics of "offsets" across
the JITs of different architectures (maybe it's good to clean that
up).  RV64 and RV32 JITs are doing something similar to arm64 with
respect to offsets.  CCing Björn and Luke.