1 // SPDX-License-Identifier: GPL-2.0-only
2 /* Copyright (c) 2020 Facebook */
3 #include <stddef.h>
4 #include <linux/bpf.h>
5 #include <bpf/bpf_helpers.h>
6 #include "bpf_misc.h"
7 
8 #define MAX_STACK (512 - 3 * 32 + 8)
9 
10 static __attribute__ ((noinline))
11 int f0(int var, struct __sk_buff *skb)
12 {
13 	return skb->len;
14 }
15 
16 __attribute__ ((noinline))
17 int f1(struct __sk_buff *skb)
18 {
19 	volatile char buf[MAX_STACK] = {};
20 
21 	return f0(0, skb) + skb->len;
22 }
23 
24 int f3(int, struct __sk_buff *skb, int);
25 
26 __attribute__ ((noinline))
27 int f2(int val, struct __sk_buff *skb)
28 {
29 	return f1(skb) + f3(val, skb, 1);
30 }
31 
32 __attribute__ ((noinline))
33 int f3(int val, struct __sk_buff *skb, int var)
34 {
35 	volatile char buf[MAX_STACK] = {};
36 
37 	return skb->ifindex * val * var;
38 }
39 
40 SEC("tc")
41 __failure __msg("combined stack size of 4 calls is 544")
42 int global_func1(struct __sk_buff *skb)
43 {
44 	return f0(1, skb) + f1(skb) + f2(2, skb) + f3(3, skb, 4);
45 }
46