Function bpf_map_update_elem 

pub fn bpf_map_update_elem<F: KernelAuxiliaryOps>(
    arg: BpfMapUpdateArg,
) -> BpfResult<()>

Create or update an element (key/value pair) in a specified map.

See https://ebpf-docs.dylanreimerink.nl/linux/syscall/BPF_MAP_UPDATE_ELEM/