#include "../../include/bpf_api.h"

/* This example demonstrates how classifier run-time behaviour

 * can be altered with tail calls. We start out with an empty

 * jmp_tc array, then add section aaa to the array slot 0, and

 * later on atomically replace it with section bbb. Note that

 * as shown in other examples, the tc loader can prepopulate

 * tail called sections, here we start out with an empty one

 * on purpose to show it can also be done this way.

 *

 * tc filter add dev foo parent ffff: bpf obj graft.o

 * tc exec bpf dbg

 *   [...]

 *   Socket Thread-20229 [001] ..s. 138993.003923: : fallthrough

 *   <idle>-0            [001] ..s. 138993.202265: : fallthrough

 *   Socket Thread-20229 [001] ..s. 138994.004149: : fallthrough

 *   [...]

 *

 * tc exec bpf graft m:globals/jmp_tc key 0 obj graft.o sec aaa

 * tc exec bpf dbg

 *   [...]

 *   Socket Thread-19818 [002] ..s. 139012.053587: : aaa

 *   <idle>-0            [002] ..s. 139012.172359: : aaa

 *   Socket Thread-19818 [001] ..s. 139012.173556: : aaa

 *   [...]

 *

 * tc exec bpf graft m:globals/jmp_tc key 0 obj graft.o sec bbb

 * tc exec bpf dbg

 *   [...]

 *   Socket Thread-19818 [002] ..s. 139022.102967: : bbb

 *   <idle>-0            [002] ..s. 139022.155640: : bbb

 *   Socket Thread-19818 [001] ..s. 139022.156730: : bbb

 *   [...]

 */

struct bpf_elf_map __section_maps jmp_tc = {

	.type		= BPF_MAP_TYPE_PROG_ARRAY,

	.size_key	= sizeof(uint32_t),

	.size_value	= sizeof(uint32_t),

	.pinning	= PIN_GLOBAL_NS,

	.max_elem	= 1,

};

__section("aaa")

int cls_aaa(struct __sk_buff *skb)

{

	printt("aaa\n");

	return TC_H_MAKE(1, 42);

}

__section("bbb")

int cls_bbb(struct __sk_buff *skb)

{

	printt("bbb\n");

	return TC_H_MAKE(1, 43);

}

__section_cls_entry

int cls_entry(struct __sk_buff *skb)

{

	tail_call(skb, &jmp_tc, 0);

	printt("fallthrough\n");

	return BPF_H_DEFAULT;

}

BPF_LICENSE("GPL");