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 
8 typedef __u64 stack_trace_t[TEST_STACK_DEPTH];
9 
10 struct {
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 
17 struct {
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 
24 struct {
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 
31 int pid = 0;
32 int control = 0;
33 int failed = 0;
34 
35 SEC("tracepoint/sched/sched_switch")
36 int 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 
68 char _license[] SEC("license") = "GPL";
69