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))
f0(int var,struct __sk_buff * skb)11 int f0(int var, struct __sk_buff *skb)
12 {
13 asm volatile ("");
14
15 return skb->len;
16 }
17
18 __attribute__ ((noinline))
f1(struct __sk_buff * skb)19 int f1(struct __sk_buff *skb)
20 {
21 volatile char buf[MAX_STACK] = {};
22
23 __sink(buf[MAX_STACK - 1]);
24
25 return f0(0, skb) + skb->len;
26 }
27
28 int f3(int, struct __sk_buff *skb, int);
29
30 __attribute__ ((noinline))
f2(int val,struct __sk_buff * skb)31 int f2(int val, struct __sk_buff *skb)
32 {
33 return f1(skb) + f3(val, skb, 1);
34 }
35
36 __attribute__ ((noinline))
f3(int val,struct __sk_buff * skb,int var)37 int f3(int val, struct __sk_buff *skb, int var)
38 {
39 volatile char buf[MAX_STACK] = {};
40
41 __sink(buf[MAX_STACK - 1]);
42
43 return skb->ifindex * val * var;
44 }
45
46 SEC("tc")
47 __failure __msg("combined stack size of 4 calls is 544")
global_func1(struct __sk_buff * skb)48 int global_func1(struct __sk_buff *skb)
49 {
50 return f0(1, skb) + f1(skb) + f2(2, skb) + f3(3, skb, 4);
51 }
52