1#include <linux/ptrace.h>
2#include <linux/version.h>
3#include <uapi/linux/bpf.h>
4#include <bpf/bpf_helpers.h>
5#include <bpf/bpf_tracing.h>
6#include <bpf/bpf_core_read.h>
7
8struct {
9	__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
10	__uint(key_size, sizeof(int));
11	__uint(value_size, sizeof(u32));
12	__uint(max_entries, 64);
13} counters SEC(".maps");
14
15struct {
16	__uint(type, BPF_MAP_TYPE_HASH);
17	__type(key, int);
18	__type(value, u64);
19	__uint(max_entries, 64);
20} values SEC(".maps");
21
22struct {
23	__uint(type, BPF_MAP_TYPE_HASH);
24	__type(key, int);
25	__type(value, struct bpf_perf_event_value);
26	__uint(max_entries, 64);
27} values2 SEC(".maps");
28
29SEC("kprobe/htab_map_get_next_key")
30int bpf_prog1(struct pt_regs *ctx)
31{
32	u32 key = bpf_get_smp_processor_id();
33	u64 count, *val;
34	s64 error;
35
36	count = bpf_perf_event_read(&counters, key);
37	error = (s64)count;
38	if (error <= -2 && error >= -22)
39		return 0;
40
41	val = bpf_map_lookup_elem(&values, &key);
42	if (val)
43		*val = count;
44	else
45		bpf_map_update_elem(&values, &key, &count, BPF_NOEXIST);
46
47	return 0;
48}
49
50/*
51 * Since *_map_lookup_elem can't be expected to trigger bpf programs
52 * due to potential deadlocks (bpf_disable_instrumentation), this bpf
53 * program will be attached to bpf_map_copy_value (which is called
54 * from map_lookup_elem) and will only filter the hashtable type.
55 */
56SEC("kprobe/bpf_map_copy_value")
57int BPF_KPROBE(bpf_prog2, struct bpf_map *map)
58{
59	u32 key = bpf_get_smp_processor_id();
60	struct bpf_perf_event_value *val, buf;
61	enum bpf_map_type type;
62	int error;
63
64	type = BPF_CORE_READ(map, map_type);
65	if (type != BPF_MAP_TYPE_HASH)
66		return 0;
67
68	error = bpf_perf_event_read_value(&counters, key, &buf, sizeof(buf));
69	if (error)
70		return 0;
71
72	val = bpf_map_lookup_elem(&values2, &key);
73	if (val)
74		*val = buf;
75	else
76		bpf_map_update_elem(&values2, &key, &buf, BPF_NOEXIST);
77
78	return 0;
79}
80
81char _license[] SEC("license") = "GPL";
82u32 _version SEC("version") = LINUX_VERSION_CODE;
83