[PATCH 4/7] ftrace, PPC: use probe_kernel API to modify code

[Paul Mackerras]

Steven Rostedt writes:

> Impact: use cleaner probe_kernel API over assembly
> 
> Using probe_kernel_read/write interface is a much cleaner approach
> than the current assembly version.

Possibly naive question: how is it possible for the accesses to the
instructions to fault, given that we are called through kstop_machine
(according to the comment) and nothing else should be happening?

Paul.