From: Xu Yang xu.yang_2@nxp.com

When do perf stat on sys metric, perf tool output nothing now: $ perf stat -a -M imx95_ddr_read.all -I 1000 $

This command runs on an arm64 machine and the Soc has one DDR hw pmu except one armv8_cortex_a55 pmu. Their maps show as follows:

const struct pmu_events_map pmu_events_map[] = { { .arch = "arm64", .cpuid = "0x00000000410fd050", .event_table = { .pmus = pmu_events__arm_cortex_a55, .num_pmus = ARRAY_SIZE(pmu_events__arm_cortex_a55) }, .metric_table = { .pmus = NULL, .num_pmus = 0 } },

static const struct pmu_sys_events pmu_sys_event_tables[] = { { .event_table = { .pmus = pmu_events__freescale_imx95_sys, .num_pmus = ARRAY_SIZE(pmu_events__freescale_imx95_sys) }, .metric_table = { .pmus = pmu_metrics__freescale_imx95_sys, .num_pmus = ARRAY_SIZE(pmu_metrics__freescale_imx95_sys) }, .name = "pmu_events__freescale_imx95_sys", },

Currently, pmu_metrics_table__find() will return NULL when only do perf stat on sys metric. Then parse_groups() will never be called to parse sys metric_name, finally perf tool will exit directly. This should be a common problem. To fix the issue, this will keep the logic before commit f20c15d13f01 ("perf pmu-events: Remember the perf_events_map for a PMU") to return a empty metric table rather than a NULL pointer. This should be fine since the removed part just check if the table match provided metric_name. Without these code, the code in parse_groups() will also check the validity of metrci_name too.

Fixes: f20c15d13f01 ("perf pmu-events: Remember the perf_events_map for a PMU") Cc: stable@vger.kernel.org Signed-off-by: Xu Yang xu.yang_2@nxp.com Acked-by: Ian Rogers irogers@google.com Signed-off-by: Ian Rogers irogers@google.com --- tools/perf/pmu-events/empty-pmu-events.c | 12 +----------- tools/perf/pmu-events/jevents.py | 12 +----------- 2 files changed, 2 insertions(+), 22 deletions(-)

diff --git a/tools/perf/pmu-events/empty-pmu-events.c b/tools/perf/pmu-events/empty-pmu-events.c index 2b7516946ded..b8719dab264d 100644 --- a/tools/perf/pmu-events/empty-pmu-events.c +++ b/tools/perf/pmu-events/empty-pmu-events.c @@ -585,17 +585,7 @@ const struct pmu_metrics_table *perf_pmu__find_metrics_table(struct perf_pmu *pm if (!map) return NULL;

- if (!pmu) - return &map->metric_table; - - for (size_t i = 0; i < map->metric_table.num_pmus; i++) { - const struct pmu_table_entry *table_pmu = &map->metric_table.pmus[i]; - const char *pmu_name = &big_c_string[table_pmu->pmu_name.offset]; - - if (pmu__name_match(pmu, pmu_name)) - return &map->metric_table; - } - return NULL; + return &map->metric_table; }

const struct pmu_events_table *find_core_events_table(const char *arch, const char *cpuid) diff --git a/tools/perf/pmu-events/jevents.py b/tools/perf/pmu-events/jevents.py index 6e71b09dbc2a..70f4fd5395fb 100755 --- a/tools/perf/pmu-events/jevents.py +++ b/tools/perf/pmu-events/jevents.py @@ -1101,17 +1101,7 @@ const struct pmu_metrics_table *perf_pmu__find_metrics_table(struct perf_pmu *pm if (!map) return NULL;

- if (!pmu) - return &map->metric_table; - - for (size_t i = 0; i < map->metric_table.num_pmus; i++) { - const struct pmu_table_entry *table_pmu = &map->metric_table.pmus[i]; - const char *pmu_name = &big_c_string[table_pmu->pmu_name.offset]; - - if (pmu__name_match(pmu, pmu_name)) - return &map->metric_table; - } - return NULL; + return &map->metric_table; }

const struct pmu_events_table *find_core_events_table(const char *arch, const char *cpuid)