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// SPDX-License-Identifier: GPL-2.0
#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>
struct {
__uint(type, BPF_MAP_TYPE_ARRAY);
__uint(max_entries, 1);
__uint(key_size, sizeof(__u32));
__uint(value_size, sizeof(__u32));
} nop_table SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_PROG_ARRAY);
__uint(max_entries, 3);
__uint(key_size, sizeof(__u32));
__uint(value_size, sizeof(__u32));
} jmp_table SEC(".maps");
int count = 0;
int noise = 0;
__always_inline int subprog_noise(void)
{
__u32 key = 0;
bpf_map_lookup_elem(&nop_table, &key);
return 0;
}
__noinline
int subprog_tail_2(struct __sk_buff *skb)
{
if (noise)
subprog_noise();
bpf_tail_call_static(skb, &jmp_table, 2);
return skb->len * 3;
}
__noinline
int subprog_tail_1(struct __sk_buff *skb)
{
bpf_tail_call_static(skb, &jmp_table, 1);
return skb->len * 2;
}
__noinline
int subprog_tail(struct __sk_buff *skb)
{
bpf_tail_call_static(skb, &jmp_table, 0);
return skb->len;
}
SEC("classifier/1")
int bpf_func_1(struct __sk_buff *skb)
{
return subprog_tail_2(skb);
}
SEC("classifier/2")
int bpf_func_2(struct __sk_buff *skb)
{
count++;
return subprog_tail_2(skb);
}
SEC("classifier/0")
int bpf_func_0(struct __sk_buff *skb)
{
return subprog_tail_1(skb);
}
SEC("classifier")
int entry(struct __sk_buff *skb)
{
return subprog_tail(skb);
}
char __license[] SEC("license") = "GPL";
int _version SEC("version") = 1;
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