Re: [PATCH] perf vendor events: Update datasource event name to fix duplicate events

[Ian Rogers <irogers@google.com>]

On Mon, Dec 4, 2023 at 12:22 PM Arnaldo Carvalho de Melo
<acme@kernel.org> wrote:
>
> Em Mon, Dec 04, 2023 at 05:20:46PM -0300, Arnaldo Carvalho de Melo escreveu:
> > Em Mon, Dec 04, 2023 at 12:12:54PM -0800, Ian Rogers escreveu:
> > > On Thu, Nov 23, 2023 at 8:01 AM Athira Rajeev
> > > <atrajeev@linux.vnet.ibm.com> wrote:
> > > >
> > > > Running "perf list" on powerpc fails with segfault
> > > > as below:
> > > >
> > > >    ./perf list
> > > >    Segmentation fault (core dumped)
> > > >
> > > > This happens because of duplicate events in the json list.
> > > > The powerpc Json event list contains some event with same
> > > > event name, but different event code. They are:
> > > > - PM_INST_FROM_L3MISS (Present in datasource and frontend)
> > > > - PM_MRK_DATA_FROM_L2MISS (Present in datasource and marked)
> > > > - PM_MRK_INST_FROM_L3MISS (Present in datasource and marked)
> > > > - PM_MRK_DATA_FROM_L3MISS (Present in datasource and marked)
> > > >
> > > > pmu_events_table__num_events uses the value from
> > > > table_pmu->num_entries which includes duplicate events as
> > > > well. This causes issue during "perf list" and results in
> > > > segmentation fault.
> > > >
> > > > Since both event codes are valid, append _DSRC to the Data
> > > > Source events (datasource.json), so that they would have a
> > > > unique name. Also add PM_DATA_FROM_L2MISS_DSRC and
> > > > PM_DATA_FROM_L3MISS_DSRC events. With the fix, perf list
> > > > works as expected.
> > > >
> > > > Fixes: fc1435807533 ("perf vendor events power10: Update JSON/events")
> > > > Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
> > >
> > > Given duplicate events creates broken pmu-events.c we should capture
> > > that as an exception in jevents.py. That way a JEVENTS_ARCH=all build
> > > will fail if any vendor/architecture would break in this way. We
> > > should also add JEVENTS_ARCH=all to tools/perf/tests/make. Athira, do
> > > you want to look at doing this?
> >
> > Should I go ahead and remove this patch till this is sorted out?
>
> I'll keep it, its already in tmp.perf-tools-next, we can go from there
> and improve this with follow up patches,

Agreed. I could look to do the follow up but likely won't have a
chance for a while. If others could help out it would be great. I'd
like to have the jevents and json be robust enough that we don't trip
over problems like this and the somewhat similar AmpereOne issue.

Thanks,
Ian

> - Arnaldo