packet_mmap: expose hw packet timestamps to network packet capture utilities

This patch adds a setting, PACKET_TIMESTAMP, to specify the packet
timestamp source that is exported to capture utilities like tcpdump by
packet_mmap.

PACKET_TIMESTAMP accepts the same integer bit field as
SO_TIMESTAMPING.  However, only the SOF_TIMESTAMPING_SYS_HARDWARE and
SOF_TIMESTAMPING_RAW_HARDWARE values are currently recognized by
PACKET_TIMESTAMP.  SOF_TIMESTAMPING_SYS_HARDWARE takes precedence over
SOF_TIMESTAMPING_RAW_HARDWARE if both bits are set.

If PACKET_TIMESTAMP is not set, a software timestamp generated inside
the networking stack is used (the behavior before this setting was
added).

Signed-off-by: Scott McMillan <scott.a.mcmillan@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/if_packet.h b/include/linux/if_packet.h
index 6ac23ef1801a..72bfa5a034dd 100644
--- a/include/linux/if_packet.h
+++ b/include/linux/if_packet.h
@@ -48,6 +48,7 @@ struct sockaddr_ll {
 #define PACKET_LOSS                     14
 #define PACKET_VNET_HDR                 15
 #define PACKET_TX_TIMESTAMP             16
+#define PACKET_TIMESTAMP                17
 
 struct tpacket_stats {
         unsigned int    tp_packets;