powerpc/powernv: Fix opal_exit tracepoint opcode

[Michael Ellerman]

On Tue, 2017-02-07 at 10:01:01 UTC, Michael Ellerman wrote:
> Currently the opal_exit tracepoint usually shows the opcode as 0:
> 
>   <idle>-0     [047] d.h.   635.654292: opal_entry: opcode=63
>   <idle>-0     [047] d.h.   635.654296: opal_exit: opcode=0 retval=0
>   kopald-1209  [019] d...   636.420943: opal_entry: opcode=10
>   kopald-1209  [019] d...   636.420959: opal_exit: opcode=0 retval=0
> 
> This is because we incorrectly load the opcode into r0 before calling
> __trace_opal_exit(), whereas it expects the opcode in r3 (first function
> parameter). In fact we are leaving the retval in r3, so opcode and
> retval will always show the same value.
> 
> Instead load the opcode into r3, resulting in:
> 
>   <idle>-0     [040] d.h.   636.618625: opal_entry: opcode=63
>   <idle>-0     [040] d.h.   636.618627: opal_exit: opcode=63 retval=0
> 
> Fixes: c49f63530bb6 ("powernv: Add OPAL tracepoints")
> Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>

Applied to powerpc next.

https://git.kernel.org/powerpc/c/a7e0fb6c2029a780444d09560f739e

cheers