+#ifndef __BPF_API__
+#define __BPF_API__
+
+/* Note:
+ *
+ * This file can be included into eBPF kernel programs. It contains
+ * a couple of useful helper functions, map/section ABI (bpf_elf.h),
+ * misc macros and some eBPF specific LLVM built-ins.
+ */
+
+#include <stdint.h>
+
+#include <linux/pkt_cls.h>
+#include <linux/bpf.h>
+#include <linux/filter.h>
+
+#include <asm/byteorder.h>
+
+#include "bpf_elf.h"
+
+/** Misc macros. */
+
+#ifndef __stringify
+# define __stringify(X) #X
+#endif
+
+#ifndef __maybe_unused
+# define __maybe_unused __attribute__((__unused__))
+#endif
+
+#ifndef offsetof
+# define offsetof(TYPE, MEMBER) __builtin_offsetof(TYPE, MEMBER)
+#endif
+
+#ifndef likely
+# define likely(X) __builtin_expect(!!(X), 1)
+#endif
+
+#ifndef unlikely
+# define unlikely(X) __builtin_expect(!!(X), 0)
+#endif
+
+#ifndef htons
+# define htons(X) __constant_htons((X))
+#endif
+
+#ifndef ntohs
+# define ntohs(X) __constant_ntohs((X))
+#endif
+
+#ifndef htonl
+# define htonl(X) __constant_htonl((X))
+#endif
+
+#ifndef ntohl
+# define ntohl(X) __constant_ntohl((X)
+#endif
+
+/** Section helper macros. */
+
+#ifndef __section
+# define __section(NAME) \
+ __attribute__((section(NAME), used))
+#endif
+
+#ifndef __section_tail
+# define __section_tail(ID, KEY) \
+ __section(__stringify(ID) "/" __stringify(KEY))
+#endif
+
+#ifndef __section_cls_entry
+# define __section_cls_entry \
+ __section(ELF_SECTION_CLASSIFIER)
+#endif
+
+#ifndef __section_act_entry
+# define __section_act_entry \
+ __section(ELF_SECTION_ACTION)
+#endif
+
+#ifndef __section_license
+# define __section_license \
+ __section(ELF_SECTION_LICENSE)
+#endif
+
+#ifndef __section_maps
+# define __section_maps \
+ __section(ELF_SECTION_MAPS)
+#endif
+
+/** Declaration helper macros. */
+
+#ifndef BPF_LICENSE
+# define BPF_LICENSE(NAME) \
+ char ____license[] __section_license = NAME
+#endif
+
+#ifndef __BPF_MAP
+# define __BPF_MAP(NAME, TYPE, ID, SIZE_KEY, SIZE_VALUE, PIN, MAX_ELEM) \
+ struct bpf_elf_map __section_maps NAME = { \
+ .type = (TYPE), \
+ .id = (ID), \
+ .size_key = (SIZE_KEY), \
+ .size_value = (SIZE_VALUE), \
+ .pinning = (PIN), \
+ .max_elem = (MAX_ELEM), \
+ }
+#endif
+
+#ifndef BPF_HASH
+# define BPF_HASH(NAME, ID, SIZE_KEY, SIZE_VALUE, PIN, MAX_ELEM) \
+ __BPF_MAP(NAME, BPF_MAP_TYPE_HASH, ID, SIZE_KEY, SIZE_VALUE, \
+ PIN, MAX_ELEM)
+#endif
+
+#ifndef BPF_ARRAY
+# define BPF_ARRAY(NAME, ID, SIZE_VALUE, PIN, MAX_ELEM) \
+ __BPF_MAP(NAME, BPF_MAP_TYPE_ARRAY, ID, sizeof(uint32_t), \
+ SIZE_VALUE, PIN, MAX_ELEM)
+#endif
+
+#ifndef BPF_ARRAY2
+# define BPF_ARRAY2(NAME, ID, PIN, MAX_ELEM) \
+ BPF_ARRAY(NAME, ID, sizeof(uint16_t), PIN, MAX_ELEM)
+#endif
+
+#ifndef BPF_ARRAY4
+# define BPF_ARRAY4(NAME, ID, PIN, MAX_ELEM) \
+ BPF_ARRAY(NAME, ID, sizeof(uint32_t), PIN, MAX_ELEM)
+#endif
+
+#ifndef BPF_ARRAY8
+# define BPF_ARRAY8(NAME, ID, PIN, MAX_ELEM) \
+ BPF_ARRAY(NAME, ID, sizeof(uint64_t), PIN, MAX_ELEM)
+#endif
+
+#ifndef BPF_PROG_ARRAY
+# define BPF_PROG_ARRAY(NAME, ID, PIN, MAX_ELEM) \
+ __BPF_MAP(NAME, BPF_MAP_TYPE_PROG_ARRAY, ID, sizeof(uint32_t), \
+ sizeof(uint32_t), PIN, MAX_ELEM)
+#endif
+
+/** Classifier helper */
+
+#ifndef BPF_H_DEFAULT
+# define BPF_H_DEFAULT -1
+#endif
+
+/** BPF helper functions for tc. */
+
+#ifndef BPF_FUNC
+# define BPF_FUNC(NAME, ...) \
+ (* NAME)(__VA_ARGS__) __maybe_unused = (void *) BPF_FUNC_##NAME
+#endif
+
+/* Map access/manipulation */
+static void *BPF_FUNC(map_lookup_elem, void *map, const void *key);
+static int BPF_FUNC(map_update_elem, void *map, const void *key,
+ const void *value, uint32_t flags);
+static int BPF_FUNC(map_delete_elem, void *map, const void *key);
+
+/* Time access */
+static uint64_t BPF_FUNC(ktime_get_ns);
+
+/* Debugging */
+static void BPF_FUNC(trace_printk, const char *fmt, int fmt_size, ...);
+
+/* Random numbers */
+static uint32_t BPF_FUNC(get_prandom_u32);
+
+/* Tail calls */
+static void BPF_FUNC(tail_call, struct __sk_buff *skb, void *map,
+ uint32_t index);
+
+/* System helpers */
+static uint32_t BPF_FUNC(get_smp_processor_id);
+
+/* Packet misc meta data */
+static uint32_t BPF_FUNC(get_cgroup_classid, struct __sk_buff *skb);
+static uint32_t BPF_FUNC(get_route_realm, struct __sk_buff *skb);
+
+/* Packet redirection */
+static int BPF_FUNC(redirect, int ifindex, uint32_t flags);
+static int BPF_FUNC(clone_redirect, struct __sk_buff *skb, int ifindex,
+ uint32_t flags);
+
+/* Packet manipulation */
+#define BPF_PSEUDO_HDR 0x10
+#define BPF_HAS_PSEUDO_HDR(flags) ((flags) & BPF_PSEUDO_HDR)
+#define BPF_HDR_FIELD_SIZE(flags) ((flags) & 0x0f)
+
+static int BPF_FUNC(skb_store_bytes, struct __sk_buff *skb, uint32_t off,
+ void *from, uint32_t len, uint32_t flags);
+static int BPF_FUNC(l3_csum_replace, struct __sk_buff *skb, uint32_t off,
+ uint32_t from, uint32_t to, uint32_t flags);
+static int BPF_FUNC(l4_csum_replace, struct __sk_buff *skb, uint32_t off,
+ uint32_t from, uint32_t to, uint32_t flags);
+
+/* Packet vlan encap/decap */
+static int BPF_FUNC(skb_vlan_push, struct __sk_buff *skb, uint16_t proto,
+ uint16_t vlan_tci);
+static int BPF_FUNC(skb_vlan_pop, struct __sk_buff *skb);
+
+/* Packet tunnel encap/decap */
+static int BPF_FUNC(skb_get_tunnel_key, struct __sk_buff *skb,
+ struct bpf_tunnel_key *to, uint32_t size, uint32_t flags);
+static int BPF_FUNC(skb_set_tunnel_key, struct __sk_buff *skb,
+ struct bpf_tunnel_key *from, uint32_t size, uint32_t flags);
+
+/** LLVM built-ins */
+
+#ifndef lock_xadd
+# define lock_xadd(ptr, val) ((void) __sync_fetch_and_add(ptr, val))
+#endif
+
+unsigned long long load_byte(void *skb, unsigned long long off)
+ asm ("llvm.bpf.load.byte");
+
+unsigned long long load_half(void *skb, unsigned long long off)
+ asm ("llvm.bpf.load.half");
+
+unsigned long long load_word(void *skb, unsigned long long off)
+ asm ("llvm.bpf.load.word");
+
+#endif /* __BPF_API__ */