timer_interrupt.c

 1// SPDX-License-Identifier: GPL-2.0
 2#include <vmlinux.h>
 3#include <bpf/bpf_helpers.h>
 4#include <bpf/bpf_tracing.h>
 5#include "bpf_experimental.h"
 6
 7char _license[] SEC("license") = "GPL";
 8
 9#define CLOCK_MONOTONIC		1
10
11int preempt_count;
12int in_interrupt;
13int in_interrupt_cb;
14
15struct elem {
16	struct bpf_timer t;
17};
18
19struct {
20	__uint(type, BPF_MAP_TYPE_ARRAY);
21	__uint(max_entries, 1);
22	__type(key, int);
23	__type(value, struct elem);
24} array SEC(".maps");
25
26static int timer_in_interrupt(void *map, int *key, struct bpf_timer *timer)
27{
28	preempt_count = get_preempt_count();
29	in_interrupt_cb = bpf_in_interrupt();
30	return 0;
31}
32
33SEC("fentry/bpf_fentry_test1")
34int BPF_PROG(test_timer_interrupt)
35{
36	struct bpf_timer *timer;
37	int key = 0;
38
39	timer = bpf_map_lookup_elem(&array, &key);
40	if (!timer)
41		return 0;
42
43	in_interrupt = bpf_in_interrupt();
44	bpf_timer_init(timer, &array, CLOCK_MONOTONIC);
45	bpf_timer_set_callback(timer, timer_in_interrupt);
46	bpf_timer_start(timer, 0, 0);
47	return 0;
48}