Add TX sending hardware timestamp.

Configure and send TX sending hardware timestamp from
 user space application to the socket layer,
 to provide to the TC ETC Qdisc, and pass it to
 the interface network driver.

 - New flag for the SO_TXTIME socket option.
 - New access auxiliary data header to pass the
   TX sending hardware timestamp.
 - Add the hardware timestamp to the socket cookie.
 - Copy the TX sending hardware timestamp to the socket cookie.

Signed-off-by: Erez Geva <erez.geva.ext@siemens.com>

include/net/sock.h

@@ -859,6 +859,7 @@ enum sock_flags {
 	SOCK_SELECT_ERR_QUEUE, /* Wake select on error queue */
 	SOCK_RCU_FREE, /* wait rcu grace period in sk_destruct() */
 	SOCK_TXTIME,
+	SOCK_HW_TXTIME,
 	SOCK_XDP, /* XDP is attached */
 	SOCK_TSTAMP_NEW, /* Indicates 64 bit timestamps always */
 };
@@ -1690,6 +1691,7 @@ void sk_send_sigurg(struct sock *sk);
 
 struct sockcm_cookie {
 	u64 transmit_time;
+	u64 transmit_hw_time;
 	u32 mark;
 	u16 tsflags;
 };

include/uapi/asm-generic/socket.h

@@ -119,6 +119,9 @@
 
 #define SO_DETACH_REUSEPORT_BPF 68
 
+#define SO_HW_TXTIME		69
+#define SCM_HW_TXTIME		SO_HW_TXTIME
+
 #if !defined(__KERNEL__)
 
 #if __BITS_PER_LONG == 64 || (defined(__x86_64__) && defined(__ILP32__))

include/uapi/linux/net_tstamp.h

@@ -162,8 +162,9 @@ struct scm_ts_pktinfo {
 enum txtime_flags {
 	SOF_TXTIME_DEADLINE_MODE = (1 << 0),
 	SOF_TXTIME_REPORT_ERRORS = (1 << 1),
+	SOF_TXTIME_USE_HW_TIMESTAMP = (1 << 2),
 
-	SOF_TXTIME_FLAGS_LAST = SOF_TXTIME_REPORT_ERRORS,
+	SOF_TXTIME_FLAGS_LAST = SOF_TXTIME_USE_HW_TIMESTAMP,
 	SOF_TXTIME_FLAGS_MASK = (SOF_TXTIME_FLAGS_LAST - 1) |
 				 SOF_TXTIME_FLAGS_LAST
 };

net/core/sock.c

@@ -1227,6 +1227,8 @@ int sock_setsockopt(struct socket *sock, int level, int optname,
 			break;
 		}
 		sock_valbool_flag(sk, SOCK_TXTIME, true);
+		sock_valbool_flag(sk, SOCK_HW_TXTIME,
+				  sk_txtime.flags & SOF_TXTIME_USE_HW_TIMESTAMP);
 		sk->sk_clockid = sk_txtime.clockid;
 		sk->sk_txtime_deadline_mode =
 			!!(sk_txtime.flags & SOF_TXTIME_DEADLINE_MODE);
@@ -2378,6 +2380,13 @@ int __sock_cmsg_send(struct sock *sk, struct msghdr *msg, struct cmsghdr *cmsg,
 			return -EINVAL;
 		sockc->transmit_time = get_unaligned((u64 *)CMSG_DATA(cmsg));
 		break;
+	case SCM_HW_TXTIME:
+		if (!sock_flag(sk, SOCK_HW_TXTIME))
+			return -EINVAL;
+		if (cmsg->cmsg_len != CMSG_LEN(sizeof(u64)))
+			return -EINVAL;
+		sockc->transmit_hw_time = get_unaligned((u64 *)CMSG_DATA(cmsg));
+		break;
 	/* SCM_RIGHTS and SCM_CREDENTIALS are semantically in SOL_UNIX. */
 	case SCM_RIGHTS:
 	case SCM_CREDENTIALS: