diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index c5bedc82bc1c540bf466c4d2e64f8663a974536d..bf38f5e8196c1bfc307405eff2b11a91059738d9 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -453,7 +453,11 @@ static unsigned int __bpf_prog_run(void *ctx, const struct bpf_insn *insn)
 		if (unlikely(!prog))
 			goto out;
 
-		ARG1 = BPF_R1;
+		/* ARG1 at this point is guaranteed to point to CTX from
+		 * the verifier side due to the fact that the tail call is
+		 * handeled like a helper, that is, bpf_tail_call_proto,
+		 * where arg1_type is ARG_PTR_TO_CTX.
+		 */
 		insn = prog->insnsi;
 		goto select_insn;
 out: