[PATCH 62/79] libperf: Add perf_evsel__open function

[Jiri Olsa]

Adding perf_evsel__open function into libperf.

It's a simplified version of evsel__open without fallback
stuff. We can try to merge it in the future to libperf,
but it has many glitches.

Link: http://lkml.kernel.org/n/tip-l21dawds9vj61pbtqhcnacqc@xxxxxxxxxxxxxx
Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
---
 tools/perf/lib/evsel.c              | 65 +++++++++++++++++++++++++++++
 tools/perf/lib/include/perf/evsel.h |  4 ++
 tools/perf/lib/libperf.map          |  1 +
 3 files changed, 70 insertions(+)

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;
+}
diff --git a/tools/perf/lib/include/perf/evsel.h b/tools/perf/lib/include/perf/evsel.h
index c01de0752e4d..adda02f00369 100644
--- a/tools/perf/lib/include/perf/evsel.h
+++ b/tools/perf/lib/include/perf/evsel.h
@@ -6,10 +6,14 @@
 #include <perf/core.h>
 
 struct perf_evsel;
+struct perf_cpu_map;
+struct perf_thread_map;
 
 LIBPERF_API void perf_evsel__init(struct perf_evsel *evsel,
 				  struct perf_event_attr *attr);
 LIBPERF_API struct perf_evsel *perf_evsel__new(struct perf_event_attr *attr);
 LIBPERF_API void perf_evsel__delete(struct perf_evsel *evsel);
+LIBPERF_API int perf_evsel__open(struct perf_evsel *evsel, struct perf_cpu_map *cpus,
+				 struct perf_thread_map *threads);
 
 #endif /* __LIBPERF_EVSEL_H */
diff --git a/tools/perf/lib/libperf.map b/tools/perf/lib/libperf.map
index 9b6e8f165014..7594d3d89c5f 100644
--- a/tools/perf/lib/libperf.map
+++ b/tools/perf/lib/libperf.map
@@ -14,6 +14,7 @@ LIBPERF_0.0.1 {
 		perf_evsel__new;
 		perf_evsel__delete;
 		perf_evsel__init;
+		perf_evsel__open;
 		perf_evlist__new;
 		perf_evlist__delete;
 		perf_evlist__init;
-- 
2.21.0