1 files changed, 65 insertions, 0 deletions
diff --git a/tools/perf/lib/evsel.c b/tools/perf/lib/evsel.c
index 027f1edb4e8e..7027dacb50f6 100644
--- a/tools/perf/lib/evsel.c
+++ b/tools/perf/lib/evsel.c
@@ -1,11 +1,17 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <errno.h>
+#include <unistd.h>
+#include <sys/syscall.h>
 #include <perf/evsel.h>
+#include <perf/cpumap.h>
+#include <perf/threadmap.h>
 #include <linux/list.h>
 #include <internal/evsel.h>
 #include <linux/zalloc.h>
 #include <stdlib.h>
 #include <internal/xyarray.h>
+#include <internal/cpumap.h>
+#include <internal/threadmap.h>
 #include <linux/string.h>
 
 void perf_evsel__init(struct perf_evsel *evsel, struct perf_event_attr *attr)
@@ -46,3 +52,62 @@ int perf_evsel__alloc_fd(struct perf_evsel *evsel, int ncpus, int nthreads)
 
 	return evsel->fd != NULL ? 0 : -ENOMEM;
 }
+
+static int
+sys_perf_event_open(struct perf_event_attr *attr,
+		    pid_t pid, int cpu, int group_fd,
+		    unsigned long flags)
+{
+	return syscall(__NR_perf_event_open, attr, pid, cpu, group_fd, flags);
+}
+
+int perf_evsel__open(struct perf_evsel *evsel, struct perf_cpu_map *cpus,
+		     struct perf_thread_map *threads)
+{
+	int cpu, thread, err = 0;
+
+	if (cpus == NULL) {
+		static struct perf_cpu_map *empty_cpu_map;
+
+		if (empty_cpu_map == NULL) {
+			empty_cpu_map = perf_cpu_map__dummy_new();
+			if (empty_cpu_map == NULL)
+				return -ENOMEM;
+		}
+
+		cpus = empty_cpu_map;
+	}
+
+	if (threads == NULL) {
+		static struct perf_thread_map *empty_thread_map;
+
+		if (empty_thread_map == NULL) {
+			empty_thread_map = perf_thread_map__new_dummy();
+			if (empty_thread_map == NULL)
+				return -ENOMEM;
+		}
+
+		threads = empty_thread_map;
+	}
+
+	if (evsel->fd == NULL &&
+	    perf_evsel__alloc_fd(evsel, cpus->nr, threads->nr) < 0)
+		return -ENOMEM;
+
+	for (cpu = 0; cpu < cpus->nr; cpu++) {
+		for (thread = 0; thread < threads->nr; thread++) {
+			int fd;
+
+			fd = sys_perf_event_open(&evsel->attr,
+						 threads->map[thread].pid,
+						 cpus->map[cpu], -1, 0);
+
+			if (fd < 0)
+				return -errno;
+
+			FD(evsel, cpu, thread) = fd;
+		}
+	}
+
+	return err;
+}