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Date: Thu, 27 May 2010 09:58:19 -0700 From: "Mcmillan, Scott A" <scott.a.mcmillan@...el.com> To: "davem@...emloft.net" <davem@...emloft.net> CC: "netdev@...r.kernel.org" <netdev@...r.kernel.org>, "tcpdump-workers@...ts.tcpdump.org" <tcpdump-workers@...ts.tcpdump.org> Subject: [PATCH] packet_mmap: expose hw packet timestamps to network packet capture utilities David, There was no negative feedback on this RFC, and the corresponding tcpdump patch was well received. Please apply. Thanks, Scott -----Original Message----- From: netdev-owner@...r.kernel.org [mailto:netdev-owner@...r.kernel.org] On Behalf Of Mcmillan, Scott A Sent: Friday, May 21, 2010 3:25 PM To: netdev@...r.kernel.org; davem@...emloft.net Cc: 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 -------------------------------------------------------------------------------- -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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