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Message-ID: <09ED21B37E0F694688A2317C4FED9ED3046E444260@azsmsx504.amr.corp.intel.com>
Date: Fri, 21 May 2010 13:24:52 -0700
From: "Mcmillan, Scott A" <scott.a.mcmillan@...el.com>
To: "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
"davem@...emloft.net" <davem@...emloft.net>
CC: "tcpdump-workers@...ts.tcpdump.org"
<tcpdump-workers@...ts.tcpdump.org>
Subject: [RFC PATCH] 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).
I am concurrently submitting a patch to the tcpdump / libpcap maintainers adding support for this capability.
Thanks,
Scott
Signed-off-by: Scott McMillan <scott.a.mcmillan@...el.com>
--- a/include/linux/if_packet.h 2010-05-18 17:22:59.000000000 -0500
+++ b/include/linux/if_packet.h 2010-05-21 14:37:30.000000000 -0500
@@ -48,6 +48,7 @@
#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;
--- a/net/packet/af_packet.c 2010-05-18 17:21:48.000000000 -0500
+++ b/net/packet/af_packet.c 2010-05-21 14:48:41.000000000 -0500
@@ -83,6 +83,7 @@
#include <linux/if_vlan.h>
#include <linux/virtio_net.h>
#include <linux/errqueue.h>
+#include <linux/net_tstamp.h>
#ifdef CONFIG_INET
#include <net/inet_common.h>
@@ -202,6 +203,7 @@
unsigned int tp_hdrlen;
unsigned int tp_reserve;
unsigned int tp_loss:1;
+ unsigned int tp_tstamp;
struct packet_type prot_hook ____cacheline_aligned_in_smp;
};
@@ -656,6 +658,7 @@
struct sk_buff *copy_skb = NULL;
struct timeval tv;
struct timespec ts;
+ struct skb_shared_hwtstamps *shhwtstamps = skb_hwtstamps(skb);
if (skb->pkt_type == PACKET_LOOPBACK)
goto drop;
@@ -737,7 +740,13 @@
h.h1->tp_snaplen = snaplen;
h.h1->tp_mac = macoff;
h.h1->tp_net = netoff;
- if (skb->tstamp.tv64)
+ if ((po->tp_tstamp & SOF_TIMESTAMPING_SYS_HARDWARE)
+ && shhwtstamps->syststamp.tv64)
+ tv = ktime_to_timeval(shhwtstamps->syststamp);
+ else if ((po->tp_tstamp & SOF_TIMESTAMPING_RAW_HARDWARE)
+ && shhwtstamps->hwtstamp.tv64)
+ tv = ktime_to_timeval(shhwtstamps->hwtstamp);
+ else if (skb->tstamp.tv64)
tv = ktime_to_timeval(skb->tstamp);
else
do_gettimeofday(&tv);
@@ -750,7 +759,13 @@
h.h2->tp_snaplen = snaplen;
h.h2->tp_mac = macoff;
h.h2->tp_net = netoff;
- if (skb->tstamp.tv64)
+ if ((po->tp_tstamp & SOF_TIMESTAMPING_SYS_HARDWARE)
+ && shhwtstamps->syststamp.tv64)
+ ts = ktime_to_timespec(shhwtstamps->syststamp);
+ else if ((po->tp_tstamp & SOF_TIMESTAMPING_RAW_HARDWARE)
+ && shhwtstamps->hwtstamp.tv64)
+ ts = ktime_to_timespec(shhwtstamps->hwtstamp);
+ else if (skb->tstamp.tv64)
ts = ktime_to_timespec(skb->tstamp);
else
getnstimeofday(&ts);
@@ -2027,6 +2042,18 @@
po->has_vnet_hdr = !!val;
return 0;
}
+ case PACKET_TIMESTAMP:
+ {
+ int val;
+
+ if (optlen != sizeof(val))
+ return -EINVAL;
+ if (copy_from_user(&val, optval, sizeof(val)))
+ return -EFAULT;
+
+ po->tp_tstamp = val;
+ return 0;
+ }
default:
return -ENOPROTOOPT;
}
@@ -2119,6 +2146,12 @@
val = po->tp_loss;
data = &val;
break;
+ case PACKET_TIMESTAMP:
+ if (len > sizeof(int))
+ len = sizeof(int);
+ val = po->tp_tstamp;
+ data = &val;
+ break;
default:
return -ENOPROTOOPT;
}
--- a/Documentation/networking/packet_mmap.txt 2010-05-18 17:24:18.000000000 -0500
+++ b/Documentation/networking/packet_mmap.txt 2010-05-21 14:39:48.000000000 -0500
@@ -493,6 +493,32 @@
pfd.events = POLLOUT;
retval = poll(&pfd, 1, timeout);
+-------------------------------------------------------------------------------
++ PACKET_TIMESTAMP
+-------------------------------------------------------------------------------
+
+The PACKET_TIMESTAMP setting determines the source of the timestamp in
+the packet meta information. If your NIC is capable of timestamping
+packets in hardware, you can request those hardware timestamps to used.
+Note: you may need to enable the generation of hardware timestamps with
+SIOCSHWTSTAMP.
+
+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 recognized by
+PACKET_TIMESTAMP. SOF_TIMESTAMPING_SYS_HARDWARE takes precedence over
+SOF_TIMESTAMPING_RAW_HARDWARE if both bits are set.
+
+ int req = 0;
+ req |= SOF_TIMESTAMPING_SYS_HARDWARE;
+ setsockopt(fd, SOL_PACKET, PACKET_TIMESTAMP, (void *) &req, sizeof(req))
+
+If PACKET_TIMESTAMP is not set, a software timestamp generated inside
+the networking stack is used (the behavior before this setting was added).
+
+See include/linux/net_tstamp.h and Documentation/networking/timestamping
+for more information on hardware timestamps.
+
--------------------------------------------------------------------------------
+ THANKS
--------------------------------------------------------------------------------
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