On 2/8/25 2:32 AM, Jason Xing wrote:
Support SCM_TSTAMP_SCHED case. Introduce SKBTX_BPF used as
an indicator telling us whether the skb should be traced
by the bpf prog.
The BPF side does not exactly support SCM_TSTAMP_SCHED as a report value.
What this patch does is:
Add a new sock_ops callback, BPF_SOCK_OPS_TS_SCHED_OPT_CB. This callback will
occur at the same timestamping point as the user space's SCM_TSTAMP_SCHED. The
BPF program can use it to get the same SCM_TSTAMP_SCHED timestamp without
modifying the user-space application.
A new SKBTX_BPF flag is added to mark skb_shinfo(skb)->tx_flags, ensuring that
the new BPF timestamping and the current user space's SO_TIMESTAMPING do not
interfere with each other.
I would remove most of the SO_TIMESTAMPING comments from the commit messages.
The timestamping points are the same but there is not much overlapping on the
API side.
Subject could be:
bpf: Add BPF_SOCK_OPS_TS_SCHED_OPT_CB callback
[ The same probably for patch 7-9. ]
Signed-off-by: Jason Xing <kerneljasonxing@xxxxxxxxx>
---
include/linux/skbuff.h | 6 +++++-
include/uapi/linux/bpf.h | 4 ++++
net/core/dev.c | 3 ++-
net/core/skbuff.c | 20 ++++++++++++++++++++
tools/include/uapi/linux/bpf.h | 4 ++++
5 files changed, 35 insertions(+), 2 deletions(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index bb2b751d274a..52f6e033e704 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -489,10 +489,14 @@ enum {
/* generate software time stamp when entering packet scheduling */
SKBTX_SCHED_TSTAMP = 1 << 6,
+
+ /* used for bpf extension when a bpf program is loaded */
+ SKBTX_BPF = 1 << 7,
};
#define SKBTX_ANY_SW_TSTAMP (SKBTX_SW_TSTAMP | \
- SKBTX_SCHED_TSTAMP)
+ SKBTX_SCHED_TSTAMP | \
+ SKBTX_BPF)
#define SKBTX_ANY_TSTAMP (SKBTX_HW_TSTAMP | \
SKBTX_HW_TSTAMP_USE_CYCLES | \
SKBTX_ANY_SW_TSTAMP)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 6116eb3d1515..30d2c078966b 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -7032,6 +7032,10 @@ enum {
* by the kernel or the
* earlier bpf-progs.
*/
+ BPF_SOCK_OPS_TS_SCHED_OPT_CB, /* Called when skb is passing through
+ * dev layer when SK_BPF_CB_TX_TIMESTAMPING
+ * feature is on.
+ */
};
/* List of TCP states. There is a build check in net/ipv4/tcp.c to detect
diff --git a/net/core/dev.c b/net/core/dev.c
index afa2282f2604..d57946c96511 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4500,7 +4500,8 @@ int __dev_queue_xmit(struct sk_buff *skb, struct net_device *sb_dev)
skb_reset_mac_header(skb);
skb_assert_len(skb);
- if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_SCHED_TSTAMP))
+ if (unlikely(skb_shinfo(skb)->tx_flags &
+ (SKBTX_SCHED_TSTAMP | SKBTX_BPF)))
__skb_tstamp_tx(skb, NULL, NULL, skb->sk, SCM_TSTAMP_SCHED);
/* Disable soft irqs for various locks below. Also
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 46530d516909..6f55eb90a632 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -5555,6 +5555,23 @@ static bool skb_tstamp_tx_report_so_timestamping(struct sk_buff *skb,
return false;
}
+static void skb_tstamp_tx_report_bpf_timestamping(struct sk_buff *skb,
+ struct sock *sk,
+ int tstype)
+{
+ int op;
+
+ switch (tstype) {
+ case SCM_TSTAMP_SCHED:
+ op = BPF_SOCK_OPS_TS_SCHED_OPT_CB;
+ break;
+ default:
+ return;
+ }
+
+ bpf_skops_tx_timestamping(sk, skb, op);
+}
+
void __skb_tstamp_tx(struct sk_buff *orig_skb,
const struct sk_buff *ack_skb,
struct skb_shared_hwtstamps *hwtstamps,
@@ -5567,6 +5584,9 @@ void __skb_tstamp_tx(struct sk_buff *orig_skb,
if (!sk)
return;
+ if (skb_shinfo(orig_skb)->tx_flags & SKBTX_BPF)
+ skb_tstamp_tx_report_bpf_timestamping(orig_skb, sk, tstype);
+
if (!skb_tstamp_tx_report_so_timestamping(orig_skb, tstype, sw))
return;
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 70366f74ef4e..eed91b7296b7 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -7025,6 +7025,10 @@ enum {
* by the kernel or the
* earlier bpf-progs.
*/
+ BPF_SOCK_OPS_TS_SCHED_OPT_CB, /* Called when skb is passing through
+ * dev layer when SK_BPF_CB_TX_TIMESTAMPING
+ * feature is on.
+ */
};
/* List of TCP states. There is a build check in net/ipv4/tcp.c to detect
