1 files changed, 78 insertions, 0 deletions
diff --git a/tools/perf/util/bpf_skel/bperf_follower.bpf.c b/tools/perf/util/bpf_skel/bperf_follower.bpf.c
new file mode 100644
index 000000000000..f193998530d4
--- /dev/null
+++ b/tools/perf/util/bpf_skel/bperf_follower.bpf.c
@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+// Copyright (c) 2021 Facebook
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include "bperf_u.h"
+
+struct {
+	__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
+	__uint(key_size, sizeof(__u32));
+	__uint(value_size, sizeof(struct bpf_perf_event_value));
+	__uint(max_entries, 1);
+} diff_readings SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
+	__uint(key_size, sizeof(__u32));
+	__uint(value_size, sizeof(struct bpf_perf_event_value));
+	__uint(max_entries, 1);
+} accum_readings SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__uint(key_size, sizeof(__u32));
+	__uint(value_size, sizeof(__u32));
+} filter SEC(".maps");
+
+enum bperf_filter_type type = 0;
+int enabled = 0;
+
+SEC("fexit/XXX")
+int BPF_PROG(fexit_XXX)
+{
+	struct bpf_perf_event_value *diff_val, *accum_val;
+	__u32 filter_key, zero = 0;
+	__u32 *accum_key;
+
+	if (!enabled)
+		return 0;
+
+	switch (type) {
+	case BPERF_FILTER_GLOBAL:
+		accum_key = &zero;
+		goto do_add;
+	case BPERF_FILTER_CPU:
+		filter_key = bpf_get_smp_processor_id();
+		break;
+	case BPERF_FILTER_PID:
+		filter_key = bpf_get_current_pid_tgid() & 0xffffffff;
+		break;
+	case BPERF_FILTER_TGID:
+		filter_key = bpf_get_current_pid_tgid() >> 32;
+		break;
+	default:
+		return 0;
+	}
+
+	accum_key = bpf_map_lookup_elem(&filter, &filter_key);
+	if (!accum_key)
+		return 0;
+
+do_add:
+	diff_val = bpf_map_lookup_elem(&diff_readings, &zero);
+	if (!diff_val)
+		return 0;
+
+	accum_val = bpf_map_lookup_elem(&accum_readings, accum_key);
+	if (!accum_val)
+		return 0;
+
+	accum_val->counter += diff_val->counter;
+	accum_val->enabled += diff_val->enabled;
+	accum_val->running += diff_val->running;
+
+	return 0;
+}
+
+char LICENSE[] SEC("license") = "Dual BSD/GPL";