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 260
 9
10static __attribute__ ((noinline))
11int f0(int var, struct __sk_buff *skb)
12{
13	asm volatile ("");
14
15	return skb->len;
16}
17
18__attribute__ ((noinline))
19int 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
28int f3(int, struct __sk_buff *skb, int);
29
30__attribute__ ((noinline))
31int f2(int val, struct __sk_buff *skb)
32{
33	volatile char buf[MAX_STACK] = {};
34
35	__sink(buf[MAX_STACK - 1]);
36
37	return f1(skb) + f3(val, skb, 1);
38}
39
40__attribute__ ((noinline))
41int f3(int val, struct __sk_buff *skb, int var)
42{
43	volatile char buf[MAX_STACK] = {};
44
45	__sink(buf[MAX_STACK - 1]);
46
47	return skb->ifindex * val * var;
48}
49
50SEC("tc")
51__failure __msg("combined stack size of 3 calls is")
52int global_func1(struct __sk_buff *skb)
53{
54	return f0(1, skb) + f1(skb) + f2(2, skb) + f3(3, skb, 4);
55}

 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
10static __attribute__ ((noinline))
11int f0(int var, struct __sk_buff *skb)
12{
13	asm volatile ("");
14
15	return skb->len;
16}
17
18__attribute__ ((noinline))
19int 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
28int f3(int, struct __sk_buff *skb, int);
29
30__attribute__ ((noinline))
31int f2(int val, struct __sk_buff *skb)
32{
 
 
 
 
33	return f1(skb) + f3(val, skb, 1);
34}
35
36__attribute__ ((noinline))
37int 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
46SEC("tc")
47__failure __msg("combined stack size of 4 calls is 544")
48int global_func1(struct __sk_buff *skb)
49{
50	return f0(1, skb) + f1(skb) + f2(2, skb) + f3(3, skb, 4);
51}