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} 56