[PATCH 06/14] powerpc/64s: interrupt replay balance the return branch predictor
Michael Ellerman
mpe at ellerman.id.au
Tue Jun 13 19:51:19 AEST 2017
Nicholas Piggin <npiggin at gmail.com> writes:
> The __replay_interrupt code is branched to with bl, but the caller is
> returned to directly with rfid from the interrupt.
>
> Instead return to a return stub that returns to the caller with blr,
> which should do better with the return predictor.
>
> Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
> ---
> arch/powerpc/kernel/exceptions-64s.S | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
> index a04ee0d7f88e..d55201625ea3 100644
> --- a/arch/powerpc/kernel/exceptions-64s.S
> +++ b/arch/powerpc/kernel/exceptions-64s.S
> @@ -1586,7 +1586,7 @@ _GLOBAL(__replay_interrupt)
> * we don't give a damn about, so we don't bother storing them.
> */
> mfmsr r12
> - mflr r11
> + LOAD_REG_ADDR(r11, __replay_interrupt_return)
Can you make it a local label, to make it clear nothing outside the file
returns to there, and to not clutter the symbol map?
cheers
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