net/tls: add device decrypted trace point

Add a tracepoint to the TLS offload's fast path. This tracepoint
can be used to track the decrypted and encrypted status of received
records. Records decrypted by the device should have decrypted set
to 1, records which have neither decrypted nor decrypted set are
partially decrypted, require re-encryption and therefore are most
expensive to deal with.

Signed-off-by: Jakub Kicinski <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/tls/tls_device.c

···
 {
 	struct tls_context *tls_ctx = tls_get_ctx(sk);
 	struct tls_offload_context_rx *ctx = tls_offload_ctx_rx(tls_ctx);
+	struct strp_msg *rxm = strp_msg(skb);
 	int is_decrypted = skb->decrypted;
 	int is_encrypted = !is_decrypted;
 	struct sk_buff *skb_iter;
···
 		is_decrypted &= skb_iter->decrypted;
 		is_encrypted &= !skb_iter->decrypted;
 	}
+
+	trace_tls_device_decrypted(sk, tcp_sk(sk)->copied_seq - rxm->full_len,
+				   tls_ctx->rx.rec_seq, rxm->full_len,
+				   is_encrypted, is_decrypted);
 
 	ctx->sw.decrypted |= is_decrypted;
 

net/tls/trace.h

···
 	)
 );
 
+TRACE_EVENT(tls_device_decrypted,
+
+	TP_PROTO(struct sock *sk, u32 tcp_seq, u8 *rec_no, u32 rec_len,
+		 bool encrypted, bool decrypted),
+
+	TP_ARGS(sk, tcp_seq, rec_no, rec_len, encrypted, decrypted),
+
+	TP_STRUCT__entry(
+		__field(	struct sock *,	sk		)
+		__field(	u64,		rec_no		)
+		__field(	u32,		tcp_seq		)
+		__field(	u32,		rec_len		)
+		__field(	bool,		encrypted	)
+		__field(	bool,		decrypted	)
+	),
+
+	TP_fast_assign(
+		__entry->sk = sk;
+		__entry->rec_no = get_unaligned_be64(rec_no);
+		__entry->tcp_seq = tcp_seq;
+		__entry->rec_len = rec_len;
+		__entry->encrypted = encrypted;
+		__entry->decrypted = decrypted;
+	),
+
+	TP_printk(
+		"sk=%p tcp_seq=%u rec_no=%llu len=%u encrypted=%d decrypted=%d",
+		__entry->sk, __entry->tcp_seq,
+		__entry->rec_no, __entry->rec_len,
+		__entry->encrypted, __entry->decrypted
+	)
+);
+
 TRACE_EVENT(tls_device_rx_resync_send,
 
 	TP_PROTO(struct sock *sk, u32 tcp_seq, u8 *rec_no, int sync_type),