Unwinding stack frame

Hi,
We are using MPC 8541 processor. Running Linux 2.6.11.
 
I have a question regarding unwinding stack frame in userland.
 
To understand the stack frame format, I am using gdb to walk through
nested function calls frame.
I am not able to understand where the PC (program counter) of callee
functions is saved on the stack/register.
 
Here are my questions:
1- Is there any available software like "pstack" ported to powerpc that
I can use?
I know the stack pointer of  the last frame is save in "R1" register.
2- How about PC, and number of the input parameters to the function.
 
Many thanks in advance,
BZ