more on FP operations

[David Miller]

I'm running test_verifier for testing, and I notice in my JIT that a
32-bit move from the frame pointer (BPF_REG_10) ends up in the JIT.

It is from this test:

                "unpriv: partial copy of pointer",
                .insns = {
                        BPF_MOV32_REG(BPF_REG_1, BPF_REG_10),
                        BPF_MOV64_IMM(BPF_REG_0, 0),
                        BPF_EXIT_INSN(),
                },
                .errstr_unpriv = "R10 partial copy",
                .result_unpriv = REJECT,
                .result = ACCEPT,

It seems to suggest that privileged code is allowed to do this, but I
can't think of a legitimate usage.

I really want to be able to JIT anything the verifier accepts, but I
have a hard time justifying adding 32-bit FP register move support,
adjusting for the stack bias, etc.

Thanks.