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 asm volatile (""); 14 15 return skb->len; 16 } 17 18 __attribute__ ((noinline)) 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)) 31 int f2(int val, struct __sk_buff *skb) 32 { 33 return f1(skb) + f3(val, skb, 1); 34 } 35 36 __attribute__ ((noinline)) 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") 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