how to get a process backtrace from kernel gdb?

[Srinivas Kommu <kommu@xxxxxxxxxxx>]

I'm running gdb on vmlinux connected to a remote target (2.4 kernel). I 
have the task_struct address of 'current' and other processes. Is it 
possible to get a symbolic stack trace of the kernel stack? Where is the 
kernel stack located? I tried to print (task_struct->reg29)[13]. Is this 
the PC?

thanks
srini

PS. I broke into gdb using a hotkey on the serial console; so the gdb 
backtrace shows the serial driver.