Subject: [PATCH net-next 3/9] net-timestamp: introduce TS_SW_OPT_CB to generate driver timestamp

From: Jason Xing <[email-masked]>
Date: Tue, 8 Oct 2024 17:51:03 +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              | 8 +++++++-
 tools/include/uapi/linux/bpf.h | 5 +++++
 3 files changed, 17 insertions(+), 1 deletion(-)

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 e697f50d1182..8faaa96c026b 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -5556,11 +5556,17 @@ static bool bpf_skb_tstamp_tx(struct sock *sk, u32 scm_flag,
 		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 true;
 		}
 
-		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);
 		return true;
 	}
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