1 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
2 // Copyright (c) 2020 Facebook
3 #include <vmlinux.h>
4 #include <bpf/bpf_helpers.h>
5 #include <bpf/bpf_tracing.h>
6
7 /* map of perf event fds, num_cpu * num_metric entries */
8 struct {
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");
13
14 /* readings at fentry */
15 struct {
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");
20
21 /* accumulated readings */
22 struct {
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");
27
28 /* sample counts, one per cpu */
29 struct {
30 __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
31 __uint(key_size, sizeof(u32));
32 __uint(value_size, sizeof(u64));
33 } counts SEC(".maps");
34
35 const volatile __u32 num_cpu = 1;
36 const volatile __u32 num_metric = 1;
37 #define MAX_NUM_MATRICS 4
38
39 SEC("fentry/XXX")
BPF_PROG(fentry_XXX)40 int BPF_PROG(fentry_XXX)
41 {
42 struct bpf_perf_event_value *ptrs[MAX_NUM_MATRICS];
43 u32 key = bpf_get_smp_processor_id();
44 u32 i;
45
46 /* look up before reading, to reduce error */
47 for (i = 0; i < num_metric && i < MAX_NUM_MATRICS; i++) {
48 u32 flag = i;
49
50 ptrs[i] = bpf_map_lookup_elem(&fentry_readings, &flag);
51 if (!ptrs[i])
52 return 0;
53 }
54
55 for (i = 0; i < num_metric && i < MAX_NUM_MATRICS; i++) {
56 struct bpf_perf_event_value reading;
57 int err;
58
59 err = bpf_perf_event_read_value(&events, key, &reading,
60 sizeof(reading));
61 if (err)
62 return 0;
63 *(ptrs[i]) = reading;
64 key += num_cpu;
65 }
66
67 return 0;
68 }
69
70 static inline void
fexit_update_maps(u32 id,struct bpf_perf_event_value * after)71 fexit_update_maps(u32 id, struct bpf_perf_event_value *after)
72 {
73 struct bpf_perf_event_value *before, diff;
74
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;
79
80 diff.counter = after->counter - before->counter;
81 diff.enabled = after->enabled - before->enabled;
82 diff.running = after->running - before->running;
83
84 accum = bpf_map_lookup_elem(&accum_readings, &id);
85 if (accum) {
86 accum->counter += diff.counter;
87 accum->enabled += diff.enabled;
88 accum->running += diff.running;
89 }
90 }
91 }
92
93 SEC("fexit/XXX")
BPF_PROG(fexit_XXX)94 int BPF_PROG(fexit_XXX)
95 {
96 struct bpf_perf_event_value readings[MAX_NUM_MATRICS];
97 u32 cpu = bpf_get_smp_processor_id();
98 u32 i, zero = 0;
99 int err;
100 u64 *count;
101
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));
106 if (err)
107 return 0;
108 }
109 count = bpf_map_lookup_elem(&counts, &zero);
110 if (count) {
111 *count += 1;
112 for (i = 0; i < num_metric && i < MAX_NUM_MATRICS; i++)
113 fexit_update_maps(i, &readings[i]);
114 }
115 return 0;
116 }
117
118 char LICENSE[] SEC("license") = "Dual BSD/GPL";
119