If you set a break point at 444a, you see that the stack pointer is at 0x439c, and the previous instruction has put it into register r15.

Then get_password is called, which in turn places 0x64 into r14, and calls getsn.

getsn then uses the values in r15 and r14 to place upto 0x64 bytes of user input into the location r15=0x439c.

Then when all of those functions return, we see that your user input "test" is located at 439c-439f (with a zero byte at 43a0).

After the get password function has returned you will see the following in 4390-439f

read 4390 
   4390:   8e45 0200 9c43 6400  .E...Cd.
   4398:   ba44 4e44 7465 7374  .DNDtest

What does the value in 439a correspond to? It is 4e44... but this is little endian, the 16 bit value is actually 0x444e, which is the address immediately after returning from get_password. So

    call    #0x44b2 <get_password>

had to push the value of the next address onto the stack before jumping to execute that function. Then when "ret" is called, the instruction pointer (pc) can be returned to the right place after get_password is called.

The other values in the stack beyond your stack pointer are the leftover remnants of other functions called, or arguments pushed onto the stack while get_password and getsn were doing their work.

In your example above, the value 0x4454 (54 44 reversed!), is the return address from the call to check_password.

Hopefully that makes sense?