samples/bpf: example of get selected PMU counter value

This is a simple example and shows how to use the new ability
to get the selected Hardware PMU counter value.

Signed-off-by: Kaixu Xia <xiakaixu@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 26 insertions, 0 deletions

diff --git a/samples/bpf/tracex6_kern.c b/samples/bpf/tracex6_kern.c
new file mode 100644
index 000000000000..23d1cffaf249
--- /dev/null
+++ b/samples/bpf/tracex6_kern.c
@@ -0,0 +1,26 @@
+#include <linux/version.h>
+#include <uapi/linux/bpf.h>
+#include "bpf_helpers.h"
+
+struct bpf_map_def SEC("maps") my_map = {
+	.type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
+	.key_size = sizeof(int),
+	.value_size = sizeof(u32),
+	.max_entries = 32,
+};
+
+SEC("kprobe/sys_write")
+int bpf_prog1(struct pt_regs *ctx)
+{
+	u64 count;
+	u32 key = bpf_get_smp_processor_id();
+	char fmt[] = "CPU-%d   %llu\n";
+
+	count = bpf_perf_event_read(&my_map, key);
+	bpf_trace_printk(fmt, sizeof(fmt), key, count);
+
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";
+u32 _version SEC("version") = LINUX_VERSION_CODE;