[PATCH v3 8/8] perf: arm_spe: Add support for SPEv1.2 inverted event filtering

[Rob Herring]

On Mon, Nov 7, 2022 at 1:48 PM Namhyung Kim <namhyung at kernel.org> wrote:
>
> Hello,
>
> On Fri, Nov 4, 2022 at 8:55 AM Rob Herring <robh at kernel.org> wrote:
> >
> > Arm SPEv1.2 (Arm v8.7/v9.2) adds a new feature called Inverted Event
> > Filter which excludes samples matching the event filter. The feature
> > mirrors the existing event filter in PMSEVFR_EL1 adding a new register,
> > PMSNEVFR_EL1, which has the same event bit assignments.
>
> Just out of curiosity, is it possible to have the event filter and
> inverted filter at the same time?

Yes, that's why config3 is needed. Samples with all the events set in
PMSEVFR_EL1 and none of the events set in PMSNEVFR_EL1 are recorded.
For example if an event bit is 0 in PMSEVFR_EL1, then recorded samples
may or may not have that event. If the same event bit is then set in
PMSNEVFR_EL1, then record samples will not have that event.

> What if they have the same?

You'd get no samples.

Rob