Messages in this thread | | | From | Namhyung Kim <> | Date | Wed, 28 Jun 2023 13:05:17 -0700 | Subject | Re: [PATCH v1] perf pmus: Add placeholder core PMU |
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On Tue, Jun 27, 2023 at 8:01 PM Yang Jihong <yangjihong1@huawei.com> wrote: > > Hello, > > On 2023/6/28 2:28, Ian Rogers wrote: > > If loading a core PMU fails, legacy hardware/cache events may segv due > > to there being no PMU. Create a placeholder empty PMU for this > > case. This was discussed in: > > https://lore.kernel.org/lkml/20230614151625.2077-1-yangjihong1@huawei.com/ > > > > Reported-by: Yang Jihong <yangjihong1@huawei.com> > > Signed-off-by: Ian Rogers <irogers@google.com> > > --- > > tools/perf/util/pmu.c | 25 +++++++++++++++++++++++++ > > tools/perf/util/pmu.h | 1 + > > tools/perf/util/pmus.c | 7 ++++++- > > 3 files changed, 32 insertions(+), 1 deletion(-) > > > > diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c > > index 8d5ecd4ff1a9..7f984a7f16ca 100644 > > --- a/tools/perf/util/pmu.c > > +++ b/tools/perf/util/pmu.c > > @@ -928,6 +928,31 @@ struct perf_pmu *perf_pmu__lookup(struct list_head *pmus, int dirfd, const char > > return NULL; > > } > > > > +/* Creates the PMU when sysfs scanning fails. */ > > +struct perf_pmu *perf_pmu__create_placeholder_core_pmu(struct list_head *core_pmus) > > +{ > > + struct perf_pmu *pmu = zalloc(sizeof(*pmu)); > > + > > + if (!pmu) > > + return NULL; > > + > > + pmu->name = strdup("cpu"); > > + if (!pmu->name) { > > + free(pmu); > > + return NULL; > > + } > > + > > + pmu->is_core = true; > > + pmu->type = PERF_TYPE_RAW; > > + pmu->cpus = cpu_map__online(); > > + > > + INIT_LIST_HEAD(&pmu->format); > > + INIT_LIST_HEAD(&pmu->aliases); > > + INIT_LIST_HEAD(&pmu->caps); > > + list_add_tail(&pmu->list, core_pmus); > > + return pmu; > > +} > > + > > void perf_pmu__warn_invalid_formats(struct perf_pmu *pmu) > > { > > struct perf_pmu_format *format; > > diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h > > index 8807a624e918..203b92860e3c 100644 > > --- a/tools/perf/util/pmu.h > > +++ b/tools/perf/util/pmu.h > > @@ -286,6 +286,7 @@ int perf_pmu__event_source_devices_fd(void); > > int perf_pmu__pathname_fd(int dirfd, const char *pmu_name, const char *filename, int flags); > > > > struct perf_pmu *perf_pmu__lookup(struct list_head *pmus, int dirfd, const char *lookup_name); > > +struct perf_pmu *perf_pmu__create_placeholder_core_pmu(struct list_head *core_pmus); > > void perf_pmu__delete(struct perf_pmu *pmu); > > > > #endif /* __PMU_H */ > > diff --git a/tools/perf/util/pmus.c b/tools/perf/util/pmus.c > > index 0866dee3fc62..3cd9de42139e 100644 > > --- a/tools/perf/util/pmus.c > > +++ b/tools/perf/util/pmus.c > > @@ -153,7 +153,12 @@ static void pmu_read_sysfs(bool core_only) > > > > closedir(dir); > > if (core_only) { > > - read_sysfs_core_pmus = true; > > + if (!list_empty(&core_pmus)) > > + read_sysfs_core_pmus = true; > > + else { > > + if (perf_pmu__create_placeholder_core_pmu(&core_pmus)) > > + read_sysfs_core_pmus = true; > > + } > > } else { > > read_sysfs_core_pmus = true; > > read_sysfs_all_pmus = true; > > > Great. This patch solves the problem, the test results are shown in [1]. > > Tested-by: Yang Jihong <yangjihong1@huawei.com>
Applied to perf-tools-next, thanks!
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