In the linux/bpf.h UAPI header, we must absolutely avoid any non-fixed-sized types.
Otherwise we have serious problems on 32-bit. Unfortunately I discovered today that we have take on two such cases, sk_msg_md and sk_reuseport_md, both of which start with two void pointers. I hit this because test_verifier.c on my sparc64 box was built as a 32-bit binary and this causes a hundred or so tests to fail, and many if not all are because of the changing struct layout. I could built 64-bit but this absolutely should work properly. But for fully native 32-bit it is even worse, this will really need to be resolved because llvm/clang is always going to build the BPF programs with 64-bit void pointers. I would strongly suggest we try and fix this now if we can.
