ftrace introduces instability into kernel 2.6.27(-rc2,-rc3)

[Benjamin Herrenschmidt]

> > As you can see, it restores r1 -before- it pops r24..r31 off
> > the stack ! I let you imagine what happens if an interrupt happens
> > just in between those two instructions (mr and lmw). We don't do
> > redzones on our ABI, so basically, the registers end up corrupted
> > by the interrupt.
> 
> Ouch!  You've disassembled this without -pg too, and it does not have this 
> bug? What version of gcc do you have?

Oops, should have mentioned it ;-)

4.2.3 (Ubuntu 4.2.3-2ubuntu7)

Ben.