Share data HPS-FPGA with on-chip memory

Hello, I’ve been searching in the forum, but I didn’t find an answer. I hope someone could help me.

I’ve a de0 nano soc and I want to share data between the HPS and the FPGA using the on-chip memory. I know how to write on the memory with the HPS, but I don’t know how to access to the on-chip memory using VHDL. I read that I should export the Avalon Memory Mapped Slave but if I do it the base address is lost and then I don't know how I could access to the on-chip memory.

Thanks.