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#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 {
__uint(type, BPF_MAP_TYPE_PROG_ARRAY);
__uint(key_size, sizeof(uint32_t));
__uint(value_size, sizeof(uint32_t));
__uint(max_entries, 1);
__uint(pinning, LIBBPF_PIN_BY_NAME);
} jmp_tc __section(".maps");
__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");
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