In Emacs, how to go back to previous line position after using semantic Jump to Symbol?

Use:

C-u C-space or C-u C-@

If you want to navigate back between buffers, you can use:

C-x C-space or C-x C-@

This makes Emacs jump to the mark (and set the mark from position popped off the local mark ring) which has usually been set by a previous jump command.