1#include "vmlinux.h"
2#include <linux/version.h>
3#include <bpf/bpf_helpers.h>
4#include <bpf/bpf_tracing.h>
5#include <bpf/bpf_core_read.h>
6
7struct {
8	__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
9	__uint(key_size, sizeof(int));
10	__uint(value_size, sizeof(u32));
11	__uint(max_entries, 64);
12} counters SEC(".maps");
13
14struct {
15	__uint(type, BPF_MAP_TYPE_HASH);
16	__type(key, int);
17	__type(value, u64);
18	__uint(max_entries, 64);
19} values SEC(".maps");
20
21struct {
22	__uint(type, BPF_MAP_TYPE_HASH);
23	__type(key, int);
24	__type(value, struct bpf_perf_event_value);
25	__uint(max_entries, 64);
26} values2 SEC(".maps");
27
28SEC("kprobe/htab_map_get_next_key")
29int bpf_prog1(struct pt_regs *ctx)
30{
31	u32 key = bpf_get_smp_processor_id();
32	u64 count, *val;
33	s64 error;
34
35	count = bpf_perf_event_read(&counters, key);
36	error = (s64)count;
37	if (error <= -2 && error >= -22)
38		return 0;
39
40	val = bpf_map_lookup_elem(&values, &key);
41	if (val)
42		*val = count;
43	else
44		bpf_map_update_elem(&values, &key, &count, BPF_NOEXIST);
45
46	return 0;
47}
48
49/*
50 * Since *_map_lookup_elem can't be expected to trigger bpf programs
51 * due to potential deadlocks (bpf_disable_instrumentation), this bpf
52 * program will be attached to bpf_map_copy_value (which is called
53 * from map_lookup_elem) and will only filter the hashtable type.
54 */
55SEC("kprobe/bpf_map_copy_value")
56int BPF_KPROBE(bpf_prog2, struct bpf_map *map)
57{
58	u32 key = bpf_get_smp_processor_id();
59	struct bpf_perf_event_value *val, buf;
60	enum bpf_map_type type;
61	int error;
62
63	type = BPF_CORE_READ(map, map_type);
64	if (type != BPF_MAP_TYPE_HASH)
65		return 0;
66
67	error = bpf_perf_event_read_value(&counters, key, &buf, sizeof(buf));
68	if (error)
69		return 0;
70
71	val = bpf_map_lookup_elem(&values2, &key);
72	if (val)
73		*val = buf;
74	else
75		bpf_map_update_elem(&values2, &key, &buf, BPF_NOEXIST);
76
77	return 0;
78}
79
80char _license[] SEC("license") = "GPL";
81u32 _version SEC("version") = LINUX_VERSION_CODE;
82