Subject: [RFC PATCH net-next v6 08/13] net-timestamp: support hw SCM_TSTAMP_SND for bpf extension

From: Jason Xing <[email-masked]>
Date: Tue, 21 Jan 2025 09:28:56 +0800

In this patch, we finish the hardware part. Then bpf program can
fetch the hwstamp from skb directly.

To avoid changing so many callers using SKBTX_HW_TSTAMP from drivers,
use this simple modification like this patch does to support printing
hardware timestamp.

Signed-off-by: Jason Xing <[email-masked]>
---
 include/linux/skbuff.h         |  4 +++-
 include/uapi/linux/bpf.h       |  5 +++++
 net/core/skbuff.c              | 11 ++++++-----
 net/dsa/user.c                 |  2 +-
 net/socket.c                   |  2 +-
 tools/include/uapi/linux/bpf.h |  5 +++++
 6 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index de8d3bd311f5..df2d790ae36b 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -471,7 +471,7 @@ struct skb_shared_hwtstamps {
 /* Definitions for tx_flags in struct skb_shared_info */
 enum {
 	/* generate hardware time stamp */
-	SKBTX_HW_TSTAMP = 1 << 0,
+	__SKBTX_HW_TSTAMP = 1 << 0,
 
 	/* generate software time stamp when queueing packet to NIC */
 	SKBTX_SW_TSTAMP = 1 << 1,
@@ -495,6 +495,8 @@ enum {
 	SKBTX_BPF = 1 << 7,
 };
 
+#define SKBTX_HW_TSTAMP		(__SKBTX_HW_TSTAMP | SKBTX_BPF)
+
 #define SKBTX_ANY_SW_TSTAMP	(SKBTX_SW_TSTAMP    | \
 				 SKBTX_SCHED_TSTAMP | \
 				 SKBTX_BPF)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index a6d761f07f67..8936e1061e71 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -7032,6 +7032,11 @@ enum {
 					 * feature is on. It indicates the
 					 * recorded timestamp.
 					 */
+	BPF_SOCK_OPS_TS_HW_OPT_CB,	/* Called in hardware phase 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 288eb9869827..c769feae5162 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -5548,7 +5548,7 @@ static bool skb_enable_app_tstamp(struct sk_buff *skb, int tstype, bool sw)
 		flag = SKBTX_SCHED_TSTAMP;
 		break;
 	case SCM_TSTAMP_SND:
-		flag = sw ? SKBTX_SW_TSTAMP : SKBTX_HW_TSTAMP;
+		flag = sw ? SKBTX_SW_TSTAMP : __SKBTX_HW_TSTAMP;
 		break;
 	case SCM_TSTAMP_ACK:
 		if (TCP_SKB_CB(skb)->txstamp_ack)
@@ -5565,7 +5565,8 @@ static bool skb_enable_app_tstamp(struct sk_buff *skb, int tstype, bool sw)
 }
 
 static void skb_tstamp_tx_bpf(struct sk_buff *skb, struct sock *sk,
-			      int tstype, bool sw)
+			      int tstype, bool sw,
+			      struct skb_shared_hwtstamps *hwtstamps)
 {
 	int op;
 
@@ -5577,9 +5578,9 @@ static void skb_tstamp_tx_bpf(struct sk_buff *skb, struct sock *sk,
 		op = BPF_SOCK_OPS_TS_SCHED_OPT_CB;
 		break;
 	case SCM_TSTAMP_SND:
+		op = sw ? BPF_SOCK_OPS_TS_SW_OPT_CB : BPF_SOCK_OPS_TS_HW_OPT_CB;
 		if (!sw)
-			return;
-		op = BPF_SOCK_OPS_TS_SW_OPT_CB;
+			*skb_hwtstamps(skb) = *hwtstamps;
 		break;
 	default:
 		return;
@@ -5602,7 +5603,7 @@ void __skb_tstamp_tx(struct sk_buff *orig_skb,
 
 	/* bpf extension feature entry */
 	if (skb_shinfo(orig_skb)->tx_flags & SKBTX_BPF)
-		skb_tstamp_tx_bpf(orig_skb, sk, tstype, sw);
+		skb_tstamp_tx_bpf(orig_skb, sk, tstype, sw, hwtstamps);
 
 	/* application feature entry */
 	if (!skb_enable_app_tstamp(orig_skb, tstype, sw))
diff --git a/net/dsa/user.c b/net/dsa/user.c
index 291ab1b4acc4..ae715bf0ae75 100644
--- a/net/dsa/user.c
+++ b/net/dsa/user.c
@@ -897,7 +897,7 @@ static void dsa_skb_tx_timestamp(struct dsa_user_priv *p,
 {
 	struct dsa_switch *ds = p->dp->ds;
 
-	if (!(skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP))
+	if (!(skb_shinfo(skb)->tx_flags & __SKBTX_HW_TSTAMP))
 		return;
 
 	if (!ds->ops->port_txtstamp)
diff --git a/net/socket.c b/net/socket.c
index 262a28b59c7f..70eabb510ce6 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -676,7 +676,7 @@ void __sock_tx_timestamp(__u32 tsflags, __u8 *tx_flags)
 	u8 flags = *tx_flags;
 
 	if (tsflags & SOF_TIMESTAMPING_TX_HARDWARE) {
-		flags |= SKBTX_HW_TSTAMP;
+		flags |= __SKBTX_HW_TSTAMP;
 
 		/* PTP hardware clocks can provide a free running cycle counter
 		 * as a time base for virtual clocks. Tell driver to use the
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 73fc0a95c9ca..f1583b5814ea 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -7025,6 +7025,11 @@ enum {
 					 * feature is on. It indicates the
 					 * recorded timestamp.
 					 */
+	BPF_SOCK_OPS_TS_HW_OPT_CB,	/* Called in hardware phase 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
-- 
2.43.5