1 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
2 // Copyright (c) 2020 Facebook
4 #include <bpf/bpf_helpers.h>
5 #include <bpf/bpf_tracing.h>
7 /* map of perf event fds, num_cpu * num_metric entries */
9 __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
10 __uint(key_size, sizeof(u32));
11 __uint(value_size, sizeof(int));
12 } events SEC(".maps");
14 /* readings at fentry */
16 __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
17 __uint(key_size, sizeof(u32));
18 __uint(value_size, sizeof(struct bpf_perf_event_value));
19 } fentry_readings SEC(".maps");
21 /* accumulated readings */
23 __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
24 __uint(key_size, sizeof(u32));
25 __uint(value_size, sizeof(struct bpf_perf_event_value));
26 } accum_readings SEC(".maps");
28 /* sample counts, one per cpu */
30 __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
31 __uint(key_size, sizeof(u32));
32 __uint(value_size, sizeof(u64));
33 } counts SEC(".maps");
35 const volatile __u32 num_cpu = 1;
36 const volatile __u32 num_metric = 1;
37 #define MAX_NUM_MATRICS 4
40 int BPF_PROG(fentry_XXX)
42 struct bpf_perf_event_value *ptrs[MAX_NUM_MATRICS];
43 u32 key = bpf_get_smp_processor_id();
46 /* look up before reading, to reduce error */
47 for (i = 0; i < num_metric && i < MAX_NUM_MATRICS; i++) {
50 ptrs[i] = bpf_map_lookup_elem(&fentry_readings, &flag);
55 for (i = 0; i < num_metric && i < MAX_NUM_MATRICS; i++) {
56 struct bpf_perf_event_value reading;
59 err = bpf_perf_event_read_value(&events, key, &reading,
71 fexit_update_maps(u32 id, struct bpf_perf_event_value *after)
73 struct bpf_perf_event_value *before, diff;
75 before = bpf_map_lookup_elem(&fentry_readings, &id);
76 /* only account samples with a valid fentry_reading */
77 if (before && before->counter) {
78 struct bpf_perf_event_value *accum;
80 diff.counter = after->counter - before->counter;
81 diff.enabled = after->enabled - before->enabled;
82 diff.running = after->running - before->running;
84 accum = bpf_map_lookup_elem(&accum_readings, &id);
86 accum->counter += diff.counter;
87 accum->enabled += diff.enabled;
88 accum->running += diff.running;
94 int BPF_PROG(fexit_XXX)
96 struct bpf_perf_event_value readings[MAX_NUM_MATRICS];
97 u32 cpu = bpf_get_smp_processor_id();
102 /* read all events before updating the maps, to reduce error */
103 for (i = 0; i < num_metric && i < MAX_NUM_MATRICS; i++) {
104 err = bpf_perf_event_read_value(&events, cpu + i * num_cpu,
105 readings + i, sizeof(*readings));
109 count = bpf_map_lookup_elem(&counts, &zero);
112 for (i = 0; i < num_metric && i < MAX_NUM_MATRICS; i++)
113 fexit_update_maps(i, &readings[i]);
118 char LICENSE[] SEC("license") = "Dual BSD/GPL";