1// SPDX-License-Identifier: GPL-2.0
2#include <vmlinux.h>
3#include <bpf/bpf_helpers.h>
4
5#define TEST_STACK_DEPTH	2
6#define TEST_MAX_ENTRIES	16384
7
8typedef __u64 stack_trace_t[TEST_STACK_DEPTH];
9
10struct {
11	__uint(type, BPF_MAP_TYPE_STACK_TRACE);
12	__uint(max_entries, TEST_MAX_ENTRIES);
13	__type(key, __u32);
14	__type(value, stack_trace_t);
15} stackmap SEC(".maps");
16
17struct {
18	__uint(type, BPF_MAP_TYPE_HASH);
19	__uint(max_entries, TEST_MAX_ENTRIES);
20	__type(key, __u32);
21	__type(value, __u32);
22} stackid_hmap SEC(".maps");
23
24struct {
25	__uint(type, BPF_MAP_TYPE_ARRAY);
26	__uint(max_entries, TEST_MAX_ENTRIES);
27	__type(key, __u32);
28	__type(value, stack_trace_t);
29} stack_amap SEC(".maps");
30
31int pid = 0;
32int control = 0;
33int failed = 0;
34
35SEC("tracepoint/sched/sched_switch")
36int oncpu(struct trace_event_raw_sched_switch *ctx)
37{
38	__u32 max_len = TEST_STACK_DEPTH * sizeof(__u64);
39	__u32 key = 0, val = 0;
40	__u64 *stack_p;
41
42	if (pid != (bpf_get_current_pid_tgid() >> 32))
43		return 0;
44
45	if (control)
46		return 0;
47
48	/* it should allow skipping whole buffer size entries */
49	key = bpf_get_stackid(ctx, &stackmap, TEST_STACK_DEPTH);
50	if ((int)key >= 0) {
51		/* The size of stackmap and stack_amap should be the same */
52		bpf_map_update_elem(&stackid_hmap, &key, &val, 0);
53		stack_p = bpf_map_lookup_elem(&stack_amap, &key);
54		if (stack_p) {
55			bpf_get_stack(ctx, stack_p, max_len, TEST_STACK_DEPTH);
56			/* it wrongly skipped all the entries and filled zero */
57			if (stack_p[0] == 0)
58				failed = 1;
59		}
60	} else {
61		/* old kernel doesn't support skipping that many entries */
62		failed = 2;
63	}
64
65	return 0;
66}
67
68char _license[] SEC("license") = "GPL";
69