microcontroller - How do I use the printf function on STM32?

I am trying to figure out how to use the printf function to print to the serial port.

My current setup is STM32CubeMX generated code and SystemWorkbench32 with the STM32F407 discovery board.

I see in stdio.h that the printf prototype is defined as:

int _EXFUN(printf, (const char *__restrict, ...)
               _ATTRIBUTE ((__format__ (__printf__, 1, 2))));

What does it mean? Where is the exact location of this function definition? What would be general point of finding out how to use this kind of function to output?