On Tue, Feb 4, 2025 at 8:56 AM Martin KaFai Lau <martin.lau@xxxxxxxxx> wrote:
>
> On 1/28/25 12:46 AM, Jason Xing wrote:
> > In this patch, we finish the hardware part. Then bpf program can
> > fetch the hwstamp from skb directly.
> >
> > To avoid changing so many callers using SKBTX_HW_TSTAMP from drivers,
> > use this simple modification like this patch does to support printing
> > hardware timestamp.
> >
> > Signed-off-by: Jason Xing <kerneljasonxing@xxxxxxxxx>
> > ---
> > include/linux/skbuff.h | 4 +++-
> > include/uapi/linux/bpf.h | 7 +++++++
> > net/core/skbuff.c | 11 ++++++-----
> > net/dsa/user.c | 2 +-
> > net/socket.c | 2 +-
> > tools/include/uapi/linux/bpf.h | 7 +++++++
> > 6 files changed, 25 insertions(+), 8 deletions(-)
> >
> > diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> > index de8d3bd311f5..df2d790ae36b 100644
> > --- a/include/linux/skbuff.h
> > +++ b/include/linux/skbuff.h
> > @@ -471,7 +471,7 @@ struct skb_shared_hwtstamps {
> > /* Definitions for tx_flags in struct skb_shared_info */
> > enum {
> > /* generate hardware time stamp */
> > - SKBTX_HW_TSTAMP = 1 << 0,
> > + __SKBTX_HW_TSTAMP = 1 << 0,
> >
> > /* generate software time stamp when queueing packet to NIC */
> > SKBTX_SW_TSTAMP = 1 << 1,
> > @@ -495,6 +495,8 @@ enum {
> > SKBTX_BPF = 1 << 7,
> > };
> >
> > +#define SKBTX_HW_TSTAMP (__SKBTX_HW_TSTAMP | SKBTX_BPF)
> > +
> > #define SKBTX_ANY_SW_TSTAMP (SKBTX_SW_TSTAMP | \
> > SKBTX_SCHED_TSTAMP | \
> > SKBTX_BPF)
> > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> > index 6a1083bcf779..4c3566f623c2 100644
> > --- a/include/uapi/linux/bpf.h
> > +++ b/include/uapi/linux/bpf.h
> > @@ -7040,6 +7040,13 @@ enum {
> > * to the nic when SK_BPF_CB_TX_TIMESTAMPING
> > * feature is on.
> > */
> > + BPF_SOCK_OPS_TS_HW_OPT_CB, /* Called in hardware phase when
> > + * SK_BPF_CB_TX_TIMESTAMPING feature
> > + * is on. At the same time, hwtstamps
> > + * of skb is initialized as the
> > + * timestamp that hardware just
> > + * generates.
> > + */
> > };
> >
> > /* List of TCP states. There is a build check in net/ipv4/tcp.c to detect
> > diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> > index 288eb9869827..c769feae5162 100644
> > --- a/net/core/skbuff.c
> > +++ b/net/core/skbuff.c
> > @@ -5548,7 +5548,7 @@ static bool skb_enable_app_tstamp(struct sk_buff *skb, int tstype, bool sw)
> > flag = SKBTX_SCHED_TSTAMP;
> > break;
> > case SCM_TSTAMP_SND:
> > - flag = sw ? SKBTX_SW_TSTAMP : SKBTX_HW_TSTAMP;
> > + flag = sw ? SKBTX_SW_TSTAMP : __SKBTX_HW_TSTAMP;
> > break;
> > case SCM_TSTAMP_ACK:
> > if (TCP_SKB_CB(skb)->txstamp_ack)
> > @@ -5565,7 +5565,8 @@ static bool skb_enable_app_tstamp(struct sk_buff *skb, int tstype, bool sw)
> > }
> >
> > static void skb_tstamp_tx_bpf(struct sk_buff *skb, struct sock *sk,
> > - int tstype, bool sw)
> > + int tstype, bool sw,
> > + struct skb_shared_hwtstamps *hwtstamps)
> > {
> > int op;
> >
> > @@ -5577,9 +5578,9 @@ static void skb_tstamp_tx_bpf(struct sk_buff *skb, struct sock *sk,
> > op = BPF_SOCK_OPS_TS_SCHED_OPT_CB;
> > break;
> > case SCM_TSTAMP_SND:
> > + op = sw ? BPF_SOCK_OPS_TS_SW_OPT_CB : BPF_SOCK_OPS_TS_HW_OPT_CB;
> > if (!sw)
>
> Patch 5 mentioned hwtstamps could be NULL, so this should be "if (hwtstamps)" here.
>
> > - return;
> > - op = BPF_SOCK_OPS_TS_SW_OPT_CB;
> > + *skb_hwtstamps(skb) = *hwtstamps;
>
> Otherwise, this will crash.
Sorry, I tested it in the wrong way... Will fix it soon!
>
> pw-bot: cr
>
>
> > break;
> > default:
> > return;
