diff --git a/src/bpf_helper_defs.h b/src/bpf_helper_defs.h
index 0916f7b..5bc36cc 100644
--- a/src/bpf_helper_defs.h
+++ b/src/bpf_helper_defs.h
@@ -1742,8 +1742,18 @@ static long (*bpf_skb_get_xfrm_state)(struct __sk_buff *skb, __u32 index, struct
  * 	**BPF_F_USER_STACK**
  * 		Collect a user space stack instead of a kernel stack.
  * 	**BPF_F_USER_BUILD_ID**
- * 		Collect buildid+offset instead of ips for user stack,
- * 		only valid if **BPF_F_USER_STACK** is also specified.
+ * 		Collect (build_id, file_offset) instead of ips for user
+ * 		stack, only valid if **BPF_F_USER_STACK** is also
+ * 		specified.
+ *
+ * 		*file_offset* is an offset relative to the beginning
+ * 		of the executable or shared object file backing the vma
+ * 		which the *ip* falls in. It is *not* an offset relative
+ * 		to that object's base address. Accordingly, it must be
+ * 		adjusted by adding (sh_addr - sh_offset), where
+ * 		sh_{addr,offset} correspond to the executable section
+ * 		containing *file_offset* in the object, for comparisons
+ * 		to symbols' st_value to be valid.
  *
  * 	**bpf_get_stack**\ () can collect up to
  * 	**PERF_MAX_STACK_DEPTH** both kernel and user frames, subject
@@ -4579,4 +4589,19 @@ static long (*bpf_tcp_raw_check_syncookie_ipv4)(struct iphdr *iph, struct tcphdr
  */
 static long (*bpf_tcp_raw_check_syncookie_ipv6)(struct ipv6hdr *iph, struct tcphdr *th) = (void *) 207;
 
+/*
+ * bpf_ktime_get_tai_ns
+ *
+ * 	A nonsettable system-wide clock derived from wall-clock time but
+ * 	ignoring leap seconds.  This clock does not experience
+ * 	discontinuities and backwards jumps caused by NTP inserting leap
+ * 	seconds as CLOCK_REALTIME does.
+ *
+ * 	See: **clock_gettime**\ (**CLOCK_TAI**)
+ *
+ * Returns
+ * 	Current *ktime*.
+ */
+static __u64 (*bpf_ktime_get_tai_ns)(void) = (void *) 208;
+