bpf_loop or bpf_for_each_map_elem in bcc

[SilverPlate3]

Is it possible to use on of bpf_loop() or bpf_for_each_map_elem() in bcc?
As it copmiles but can't pass the versifier
Example code:

static long FooLoop(u64 i, void *ctx)
{
    if(i > 250)
    {
        return 1;
    }
    bpf_trace_printk("rabin_karp_loop_allocator.lookup failed");
    return 0;
}

static long Foo()
{
bpf_loop(7, FooLoop, NULL, 0);
}

Verifier error:

; bpf_loop(7, FooLoop, NULL, 0);
3841: (b7) r1 = 7                     ; R1_w=7
3842: (18) r2 = 0x0                   ; R2_w=0
3844: (b7) r3 = 0                     ; R3_w=0
3845: (b7) r4 = 0                     ; R4=0
3846: (85) call bpf_loop#181
R2 type=scalar expected=func

If yes how? Any example?
If not, why?
Thanks!

[yonghong-song]

The callback function is not supported for bcc tools. But you can try with libbpf-tools which supports callback functions.