[seL4] Get a mapping for physical memory

Hi All, I am a very beginner for sel4, and I very little about its APIs. Now I have a physical address of memory, I want to know if this address is mapped into my virtual address space. And if so, how can I know what virtual address t is mapped in? Furthermore, how can I share this piece of memory with another process/thread? I find there is a function "simple_get_frame_mapping_f“ in libsel4simple-default library. Its comment is "Request mapped address to a region of physical memory.” It is very similar to what I need, but its implementation just returns NULL.(in sel4\libs\libsel4simple-stable\src\libsel4simple-stable.c) Thank you very much. Yuxin