Subject: [PATCH net-next v2 07/12] net-timestamp: introduce TS_SW_OPT_CB to generate driver timestamp

From: Jason Xing <[email-masked]>
Date: Sat, 12 Oct 2024 12:06:46 +0800

From: Jason Xing <[email-masked]>

When the skb is about to send from driver to nic, we can print timestamp
by setting BPF_SOCK_OPS_TS_SW_OPT_CB in bpf program.

Signed-off-by: Jason Xing <[email-masked]>
---
 include/uapi/linux/bpf.h       |  5 +++++
 net/core/skbuff.c              | 13 ++++++++++---
 tools/include/uapi/linux/bpf.h |  5 +++++
 3 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 3cf3c9c896c7..0d00539f247a 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -7024,6 +7024,11 @@ enum {
 					 * feature is on. It indicates the
 					 * recorded timestamp.
 					 */
+	BPF_SOCK_OPS_TS_SW_OPT_CB,	/* Called when skb is about to send
+					 * to the nic when SO_TIMESTAMPING
+					 * feature is on. It indicates the
+					 * recorded timestamp.
+					 */
 };
 
 /* List of TCP states. There is a build check in net/ipv4/tcp.c to detect
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 16e7bdc1eacb..832d53de9874 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -5619,7 +5619,8 @@ static void skb_tstamp_tx_output(struct sk_buff *orig_skb,
 	__skb_complete_tx_timestamp(skb, sk, tstype, opt_stats);
 }
 
-static void bpf_skb_tstamp_tx_output(struct sock *sk, int tstype)
+static void bpf_skb_tstamp_tx_output(struct sock *sk, int tstype,
+				     struct skb_shared_hwtstamps *hwtstamps)
 {
 	struct tcp_sock *tp;
 	u32 tsflags;
@@ -5640,11 +5641,17 @@ static void bpf_skb_tstamp_tx_output(struct sock *sk, int tstype)
 		case SCM_TSTAMP_SCHED:
 			cb_flag = BPF_SOCK_OPS_TS_SCHED_OPT_CB;
 			break;
+		case SCM_TSTAMP_SND:
+			cb_flag = BPF_SOCK_OPS_TS_SW_OPT_CB;
+			break;
 		default:
 			return;
 		}
 
-		tstamp = ktime_to_timespec64(ktime_get_real());
+		if (hwtstamps)
+			tstamp = ktime_to_timespec64(hwtstamps->hwtstamp);
+		else
+			tstamp = ktime_to_timespec64(ktime_get_real());
 		tcp_call_bpf_2arg(sk, cb_flag, tstamp.tv_sec, tstamp.tv_nsec);
 	}
 }
@@ -5658,7 +5665,7 @@ void __skb_tstamp_tx(struct sk_buff *orig_skb,
 		return;
 
 	if (static_branch_unlikely(&bpf_tstamp_control))
-		bpf_skb_tstamp_tx_output(sk, tstype);
+		bpf_skb_tstamp_tx_output(sk, tstype, hwtstamps);
 
 	skb_tstamp_tx_output(orig_skb, ack_skb, hwtstamps, sk, tstype);
 }
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index d60675e1a5a0..020ec14ffae6 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -7023,6 +7023,11 @@ enum {
 					 * feature is on. It indicates the
 					 * recorded timestamp.
 					 */
+	BPF_SOCK_OPS_TS_SW_OPT_CB,	/* Called when skb is about to send
+					 * to the nic when SO_TIMESTAMPING
+					 * feature is on. It indicates the
+					 * recorded timestamp.
+					 */
 };
 
 /* List of TCP states. There is a build check in net/ipv4/tcp.c to detect
-- 
2.37.3