perf pmu: Add CPU map for "cpu" PMUs

A typical "cpu" PMU has no "cpus" or "cpumask" file meaning the CPU
map is set to NULL, which also encodes an empty CPU map. Update
pmu_cpumask so that if the "cpu" PMU fails to load a CPU map, use a
default of all online PMUs.

Remove const from cpu_map__online for the sake of reference counting.

Reviewed-by: Kan Liang <[email protected]>
Signed-off-by: Ian Rogers <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Ali Saidi <[email protected]>
Cc: Athira Rajeev <[email protected]>
Cc: Dmitrii Dolgov <[email protected]>
Cc: Huacai Chen <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: James Clark <[email protected]>
Cc: Jing Zhang <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: John Garry <[email protected]>
Cc: Kajol Jain <[email protected]>
Cc: Kang Minchul <[email protected]>
Cc: Leo Yan <[email protected]>
Cc: Madhavan Srinivasan <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Mike Leach <[email protected]>
Cc: Ming Wang <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Ravi Bangoria <[email protected]>
Cc: Rob Herring <[email protected]>
Cc: Sandipan Das <[email protected]>
Cc: Sean Christopherson <[email protected]>
Cc: Suzuki Poulouse <[email protected]>
Cc: Thomas Richter <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Xing Zhengjun <[email protected]>
Cc: [email protected]
Cc: [email protected]
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

3 files changed, 5 insertions, 5 deletions

diff --git a/tools/perf/util/cpumap.c b/tools/perf/util/cpumap.c
index a0719816a218..0e090e8bc334 100644
--- a/tools/perf/util/cpumap.c
+++ b/tools/perf/util/cpumap.c
@@ -667,9 +667,9 @@ size_t cpu_map__snprint_mask(struct perf_cpu_map *map, char *buf, size_t size)
 	return ptr - buf;
 }
 
-const struct perf_cpu_map *cpu_map__online(void) /* thread unsafe */
+struct perf_cpu_map *cpu_map__online(void) /* thread unsafe */
 {
-	static const struct perf_cpu_map *online = NULL;
+	static struct perf_cpu_map *online;
 
 	if (!online)
 		online = perf_cpu_map__new(NULL); /* from /sys/devices/system/cpu/online */
diff --git a/tools/perf/util/cpumap.h b/tools/perf/util/cpumap.h
index f394ccc0ccfb..9df2aeb34d3d 100644
--- a/tools/perf/util/cpumap.h
+++ b/tools/perf/util/cpumap.h
@@ -55,7 +55,7 @@ struct perf_cpu_map *cpu_map__new_data(const struct perf_record_cpu_map_data *da
 size_t cpu_map__snprint(struct perf_cpu_map *map, char *buf, size_t size);
 size_t cpu_map__snprint_mask(struct perf_cpu_map *map, char *buf, size_t size);
 size_t cpu_map__fprintf(struct perf_cpu_map *map, FILE *fp);
-const struct perf_cpu_map *cpu_map__online(void); /* thread unsafe */
+struct perf_cpu_map *cpu_map__online(void); /* thread unsafe */
 
 int cpu__setup_cpunode_map(void);
 
@@ -66,7 +66,7 @@ struct perf_cpu cpu__max_present_cpu(void);
 /**
  * cpu_map__is_dummy - Events associated with a pid, rather than a CPU, use a single dummy map with an entry of -1.
  */
-static inline bool cpu_map__is_dummy(struct perf_cpu_map *cpus)
+static inline bool cpu_map__is_dummy(const struct perf_cpu_map *cpus)
 {
 	return perf_cpu_map__nr(cpus) == 1 && perf_cpu_map__cpu(cpus, 0).cpu == -1;
 }
diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index e8c0762c311a..d992f5242d99 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -610,7 +610,7 @@ static struct perf_cpu_map *pmu_cpumask(int dirfd, const char *name)
 			return cpus;
 	}
 
-	return NULL;
+	return !strcmp(name, "cpu") ? perf_cpu_map__get(cpu_map__online()) : NULL;
 }
 
 static bool pmu_is_uncore(int dirfd, const char *name)