+/* BPF helper function descriptions:
+ *
+ * void *bpf_map_lookup_elem(&map, &key)
+ * Return: Map value or NULL
+ *
+ * int bpf_map_update_elem(&map, &key, &value, flags)
+ * Return: 0 on success or negative error
+ *
+ * int bpf_map_delete_elem(&map, &key)
+ * Return: 0 on success or negative error
+ *
+ * int bpf_probe_read(void *dst, int size, void *src)
+ * Return: 0 on success or negative error
+ *
+ * u64 bpf_ktime_get_ns(void)
+ * Return: current ktime
+ *
+ * int bpf_trace_printk(const char *fmt, int fmt_size, ...)
+ * Return: length of buffer written or negative error
+ *
+ * u32 bpf_prandom_u32(void)
+ * Return: random value
+ *
+ * u32 bpf_raw_smp_processor_id(void)
+ * Return: SMP processor ID
+ *
+ * int bpf_skb_store_bytes(skb, offset, from, len, flags)
+ * store bytes into packet
+ * @skb: pointer to skb
+ * @offset: offset within packet from skb->mac_header
+ * @from: pointer where to copy bytes from
+ * @len: number of bytes to store into packet
+ * @flags: bit 0 - if true, recompute skb->csum
+ * other bits - reserved
+ * Return: 0 on success or negative error
+ *
+ * int bpf_l3_csum_replace(skb, offset, from, to, flags)
+ * recompute IP checksum
+ * @skb: pointer to skb
+ * @offset: offset within packet where IP checksum is located
+ * @from: old value of header field
+ * @to: new value of header field
+ * @flags: bits 0-3 - size of header field
+ * other bits - reserved
+ * Return: 0 on success or negative error
+ *
+ * int bpf_l4_csum_replace(skb, offset, from, to, flags)
+ * recompute TCP/UDP checksum
+ * @skb: pointer to skb
+ * @offset: offset within packet where TCP/UDP checksum is located
+ * @from: old value of header field
+ * @to: new value of header field
+ * @flags: bits 0-3 - size of header field
+ * bit 4 - is pseudo header
+ * other bits - reserved
+ * Return: 0 on success or negative error
+ *
+ * int bpf_tail_call(ctx, prog_array_map, index)
+ * jump into another BPF program
+ * @ctx: context pointer passed to next program
+ * @prog_array_map: pointer to map which type is BPF_MAP_TYPE_PROG_ARRAY
+ * @index: index inside array that selects specific program to run
+ * Return: 0 on success or negative error
+ *
+ * int bpf_clone_redirect(skb, ifindex, flags)
+ * redirect to another netdev
+ * @skb: pointer to skb
+ * @ifindex: ifindex of the net device
+ * @flags: bit 0 - if set, redirect to ingress instead of egress
+ * other bits - reserved
+ * Return: 0 on success or negative error
+ *
+ * u64 bpf_get_current_pid_tgid(void)
+ * Return: current->tgid << 32 | current->pid
+ *
+ * u64 bpf_get_current_uid_gid(void)
+ * Return: current_gid << 32 | current_uid
+ *
+ * int bpf_get_current_comm(char *buf, int size_of_buf)
+ * stores current->comm into buf
+ * Return: 0 on success or negative error
+ *
+ * u32 bpf_get_cgroup_classid(skb)
+ * retrieve a proc's classid
+ * @skb: pointer to skb
+ * Return: classid if != 0
+ *
+ * int bpf_skb_vlan_push(skb, vlan_proto, vlan_tci)
+ * Return: 0 on success or negative error
+ *
+ * int bpf_skb_vlan_pop(skb)
+ * Return: 0 on success or negative error
+ *
+ * int bpf_skb_get_tunnel_key(skb, key, size, flags)
+ * int bpf_skb_set_tunnel_key(skb, key, size, flags)
+ * retrieve or populate tunnel metadata
+ * @skb: pointer to skb
+ * @key: pointer to 'struct bpf_tunnel_key'
+ * @size: size of 'struct bpf_tunnel_key'
+ * @flags: room for future extensions
+ * Return: 0 on success or negative error
+ *
+ * u64 bpf_perf_event_read(&map, index)
+ * Return: Number events read or error code
+ *
+ * int bpf_redirect(ifindex, flags)
+ * redirect to another netdev
+ * @ifindex: ifindex of the net device
+ * @flags: bit 0 - if set, redirect to ingress instead of egress
+ * other bits - reserved
+ * Return: TC_ACT_REDIRECT
+ *
+ * u32 bpf_get_route_realm(skb)
+ * retrieve a dst's tclassid
+ * @skb: pointer to skb
+ * Return: realm if != 0
+ *
+ * int bpf_perf_event_output(ctx, map, index, data, size)
+ * output perf raw sample
+ * @ctx: struct pt_regs*
+ * @map: pointer to perf_event_array map
+ * @index: index of event in the map
+ * @data: data on stack to be output as raw data
+ * @size: size of data
+ * Return: 0 on success or negative error
+ *
+ * int bpf_get_stackid(ctx, map, flags)
+ * walk user or kernel stack and return id
+ * @ctx: struct pt_regs*
+ * @map: pointer to stack_trace map
+ * @flags: bits 0-7 - numer of stack frames to skip
+ * bit 8 - collect user stack instead of kernel
+ * bit 9 - compare stacks by hash only
+ * bit 10 - if two different stacks hash into the same stackid
+ * discard old
+ * other bits - reserved
+ * Return: >= 0 stackid on success or negative error
+ *
+ * s64 bpf_csum_diff(from, from_size, to, to_size, seed)
+ * calculate csum diff
+ * @from: raw from buffer
+ * @from_size: length of from buffer
+ * @to: raw to buffer
+ * @to_size: length of to buffer
+ * @seed: optional seed
+ * Return: csum result or negative error code
+ *
+ * int bpf_skb_get_tunnel_opt(skb, opt, size)
+ * retrieve tunnel options metadata
+ * @skb: pointer to skb
+ * @opt: pointer to raw tunnel option data
+ * @size: size of @opt
+ * Return: option size
+ *
+ * int bpf_skb_set_tunnel_opt(skb, opt, size)
+ * populate tunnel options metadata
+ * @skb: pointer to skb
+ * @opt: pointer to raw tunnel option data
+ * @size: size of @opt
+ * Return: 0 on success or negative error
+ *
+ * int bpf_skb_change_proto(skb, proto, flags)
+ * Change protocol of the skb. Currently supported is v4 -> v6,
+ * v6 -> v4 transitions. The helper will also resize the skb. eBPF
+ * program is expected to fill the new headers via skb_store_bytes
+ * and lX_csum_replace.
+ * @skb: pointer to skb
+ * @proto: new skb->protocol type
+ * @flags: reserved
+ * Return: 0 on success or negative error
+ *
+ * int bpf_skb_change_type(skb, type)
+ * Change packet type of skb.
+ * @skb: pointer to skb
+ * @type: new skb->pkt_type type
+ * Return: 0 on success or negative error
+ *
+ * int bpf_skb_under_cgroup(skb, map, index)
+ * Check cgroup2 membership of skb
+ * @skb: pointer to skb
+ * @map: pointer to bpf_map in BPF_MAP_TYPE_CGROUP_ARRAY type
+ * @index: index of the cgroup in the bpf_map
+ * Return:
+ * == 0 skb failed the cgroup2 descendant test
+ * == 1 skb succeeded the cgroup2 descendant test
+ * < 0 error
+ *
+ * u32 bpf_get_hash_recalc(skb)
+ * Retrieve and possibly recalculate skb->hash.
+ * @skb: pointer to skb
+ * Return: hash
+ *
+ * u64 bpf_get_current_task(void)
+ * Returns current task_struct
+ * Return: current
+ *
+ * int bpf_probe_write_user(void *dst, void *src, int len)
+ * safely attempt to write to a location
+ * @dst: destination address in userspace
+ * @src: source address on stack
+ * @len: number of bytes to copy
+ * Return: 0 on success or negative error
+ *
+ * int bpf_current_task_under_cgroup(map, index)
+ * Check cgroup2 membership of current task
+ * @map: pointer to bpf_map in BPF_MAP_TYPE_CGROUP_ARRAY type
+ * @index: index of the cgroup in the bpf_map
+ * Return:
+ * == 0 current failed the cgroup2 descendant test
+ * == 1 current succeeded the cgroup2 descendant test
+ * < 0 error
+ *
+ * int bpf_skb_change_tail(skb, len, flags)
+ * The helper will resize the skb to the given new size, to be used f.e.
+ * with control messages.
+ * @skb: pointer to skb
+ * @len: new skb length
+ * @flags: reserved
+ * Return: 0 on success or negative error
+ *
+ * int bpf_skb_pull_data(skb, len)
+ * The helper will pull in non-linear data in case the skb is non-linear
+ * and not all of len are part of the linear section. Only needed for
+ * read/write with direct packet access.
+ * @skb: pointer to skb
+ * @len: len to make read/writeable
+ * Return: 0 on success or negative error
+ *
+ * s64 bpf_csum_update(skb, csum)
+ * Adds csum into skb->csum in case of CHECKSUM_COMPLETE.
+ * @skb: pointer to skb
+ * @csum: csum to add
+ * Return: csum on success or negative error
+ *
+ * void bpf_set_hash_invalid(skb)
+ * Invalidate current skb->hash.
+ * @skb: pointer to skb
+ *
+ * int bpf_get_numa_node_id()
+ * Return: Id of current NUMA node.
+ *
+ * int bpf_skb_change_head()
+ * Grows headroom of skb and adjusts MAC header offset accordingly.
+ * Will extends/reallocae as required automatically.
+ * May change skb data pointer and will thus invalidate any check
+ * performed for direct packet access.
+ * @skb: pointer to skb
+ * @len: length of header to be pushed in front
+ * @flags: Flags (unused for now)
+ * Return: 0 on success or negative error
+ *
+ * int bpf_xdp_adjust_head(xdp_md, delta)
+ * Adjust the xdp_md.data by delta
+ * @xdp_md: pointer to xdp_md
+ * @delta: An positive/negative integer to be added to xdp_md.data
+ * Return: 0 on success or negative on error
+ */
+#define __BPF_FUNC_MAPPER(FN) \
+ FN(unspec), \
+ FN(map_lookup_elem), \
+ FN(map_update_elem), \
+ FN(map_delete_elem), \
+ FN(probe_read), \
+ FN(ktime_get_ns), \
+ FN(trace_printk), \
+ FN(get_prandom_u32), \
+ FN(get_smp_processor_id), \
+ FN(skb_store_bytes), \
+ FN(l3_csum_replace), \
+ FN(l4_csum_replace), \
+ FN(tail_call), \
+ FN(clone_redirect), \
+ FN(get_current_pid_tgid), \
+ FN(get_current_uid_gid), \
+ FN(get_current_comm), \
+ FN(get_cgroup_classid), \
+ FN(skb_vlan_push), \
+ FN(skb_vlan_pop), \
+ FN(skb_get_tunnel_key), \
+ FN(skb_set_tunnel_key), \
+ FN(perf_event_read), \
+ FN(redirect), \
+ FN(get_route_realm), \
+ FN(perf_event_output), \
+ FN(skb_load_bytes), \
+ FN(get_stackid), \
+ FN(csum_diff), \
+ FN(skb_get_tunnel_opt), \
+ FN(skb_set_tunnel_opt), \
+ FN(skb_change_proto), \
+ FN(skb_change_type), \
+ FN(skb_under_cgroup), \
+ FN(get_hash_recalc), \
+ FN(get_current_task), \
+ FN(probe_write_user), \
+ FN(current_task_under_cgroup), \
+ FN(skb_change_tail), \
+ FN(skb_pull_data), \
+ FN(csum_update), \
+ FN(set_hash_invalid), \
+ FN(get_numa_node_id), \
+ FN(skb_change_head), \
+ FN(xdp_adjust_head),
+