perf pmu-events: Add pmu_events_table__find_event()

jevents stores events sorted by name. Add a find function that will
binary search event names avoiding the need to linearly search through
events.

Add a test in tests/pmu-events.c. If the PMU or event aren't found -1000
is returned. If the event is found but no callback function given, 0 is
returned.

This allows the find function also act as a test for existence.

Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Gaosheng Cui <cuigaosheng1@huawei.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jing Zhang <renyu.zj@linux.alibaba.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.g.garry@oracle.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230824041330.266337-9-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/pmu-events/empty-pmu-events.c

@@ -282,6 +282,22 @@ int pmu_events_table__for_each_event(const struct pmu_events_table *table, struc
 	return 0;
 }
 
+int pmu_events_table__find_event(const struct pmu_events_table *table,
+                                 struct perf_pmu *pmu,
+                                 const char *name,
+                                 pmu_event_iter_fn fn,
+                                 void *data)
+{
+	for (const struct pmu_event *pe = &table->entries[0]; pe->name; pe++) {
+                if (pmu && !pmu__name_match(pmu, pe->pmu))
+                        continue;
+
+		if (!strcasecmp(pe->name, name))
+			return fn(pe, table, data);
+	}
+        return -1000;
+}
+
 int pmu_metrics_table__for_each_metric(const struct pmu_metrics_table *table, pmu_metric_iter_fn fn,
 				      void *data)
 {

tools/perf/pmu-events/jevents.py

@@ -825,6 +825,49 @@ def print_system_mapping_table() -> None:
         return 0;
  }
 
+static int pmu_events_table__find_event_pmu(const struct pmu_events_table *table,
+                                            const struct pmu_table_entry *pmu,
+                                            const char *name,
+                                            pmu_event_iter_fn fn,
+                                            void *data)
+{
+        struct pmu_event pe = {
+                .pmu = &big_c_string[pmu->pmu_name.offset],
+        };
+        int low = 0, high = pmu->num_entries - 1;
+
+        while (low <= high) {
+                int cmp, mid = (low + high) / 2;
+
+                decompress_event(pmu->entries[mid].offset, &pe);
+
+                if (!pe.name && !name)
+                        goto do_call;
+
+                if (!pe.name && name) {
+                        low = mid + 1;
+                        continue;
+                }
+                if (pe.name && !name) {
+                        high = mid - 1;
+                        continue;
+                }
+
+                cmp = strcasecmp(pe.name, name);
+                if (cmp < 0) {
+                        low = mid + 1;
+                        continue;
+                }
+                if (cmp > 0) {
+                        high = mid - 1;
+                        continue;
+                }
+  do_call:
+                return fn ? fn(&pe, table, data) : 0;
+        }
+        return -1000;
+}
+
 int pmu_events_table__for_each_event(const struct pmu_events_table *table,
                                     struct perf_pmu *pmu,
                                     pmu_event_iter_fn fn,
@@ -845,6 +888,27 @@ def print_system_mapping_table() -> None:
         return 0;
 }
 
+int pmu_events_table__find_event(const struct pmu_events_table *table,
+                                 struct perf_pmu *pmu,
+                                 const char *name,
+                                 pmu_event_iter_fn fn,
+                                 void *data)
+{
+        for (size_t i = 0; i < table->num_pmus; i++) {
+                const struct pmu_table_entry *table_pmu = &table->pmus[i];
+                const char *pmu_name = &big_c_string[table_pmu->pmu_name.offset];
+                int ret;
+
+                if (!pmu__name_match(pmu, pmu_name))
+                        continue;
+
+                ret = pmu_events_table__find_event_pmu(table, table_pmu, name, fn, data);
+                if (ret != -1000)
+                        return ret;
+        }
+        return -1000;
+}
+
 static int pmu_metrics_table__for_each_metric_pmu(const struct pmu_metrics_table *table,
                                                 const struct pmu_table_entry *pmu,
                                                 pmu_metric_iter_fn fn,

tools/perf/pmu-events/pmu-events.h

@@ -81,6 +81,11 @@ int pmu_events_table__for_each_event(const struct pmu_events_table *table,
 				    struct perf_pmu *pmu,
 				    pmu_event_iter_fn fn,
 				    void *data);
+int pmu_events_table__find_event(const struct pmu_events_table *table,
+                                 struct perf_pmu *pmu,
+                                 const char *name,
+                                 pmu_event_iter_fn fn,
+				 void *data);
 int pmu_metrics_table__for_each_metric(const struct pmu_metrics_table *table, pmu_metric_iter_fn fn,
 				     void *data);
 

tools/perf/tests/pmu-events.c

@@ -546,6 +546,11 @@ static int __test_core_pmu_event_aliases(char *pmu_name, int *count)
 
 	pmu_add_cpu_aliases_table(pmu, table);
 
+	res = pmu_events_table__find_event(table, pmu, "bp_l1_btb_correct", NULL, NULL);
+	if (res != 0) {
+		pr_debug("Missing test event in test architecture");
+		return res;
+	}
 	for (; *test_event_table; test_event_table++) {
 		struct perf_pmu_test_event test_event = **test_event_table;
 		struct pmu_event const *event = &test_event.event;