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Date: Tue, 25 Oct 2022 08:17:37 +0200
From: Christian Eggers <ceggers@...i.de>
To: <linux-kernel@...r.kernel.org>, <netdev@...r.kernel.org>,
Arun Ramadoss <arun.ramadoss@...rochip.com>
CC: <woojung.huh@...rochip.com>, <UNGLinuxDriver@...rochip.com>,
<andrew@...n.ch>, <vivien.didelot@...il.com>,
<f.fainelli@...il.com>, <olteanv@...il.com>, <davem@...emloft.net>,
<edumazet@...gle.com>, <kuba@...nel.org>, <pabeni@...hat.com>,
<linux@...linux.org.uk>, <Tristram.Ha@...rochip.com>,
<richardcochran@...il.com>
Subject: Re: [RFC Patch net-next 5/6] net: dsa: microchip: Adding the ptp packet reception logic
Hi Arun,
On Friday, 14 October 2022, 17:28:56 CEST, Arun Ramadoss wrote:
> This patch adds the routines for timestamping received ptp packets.
> Whenever the ptp packet is received, the 4 byte hardware time stamped
> value is append to its packet. This 4 byte value is extracted from the
> tail tag and reconstructed to absolute time and assigned to skb
> hwtstamp.
>
> Signed-off-by: Arun Ramadoss <arun.ramadoss@...rochip.com>
> ---
> drivers/net/dsa/microchip/ksz_common.c | 12 +++++++++++
> drivers/net/dsa/microchip/ksz_ptp.c | 25 +++++++++++++++++++++
> drivers/net/dsa/microchip/ksz_ptp.h | 6 ++++++
> include/linux/dsa/ksz_common.h | 15 +++++++++++++
> net/dsa/tag_ksz.c | 30 ++++++++++++++++++++++----
> 5 files changed, 84 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/net/dsa/microchip/ksz_common.c b/drivers/net/dsa/microchip/ksz_common.c
> index 0c0fdb7b7879..388731959b23 100644
> --- a/drivers/net/dsa/microchip/ksz_common.c
> +++ b/drivers/net/dsa/microchip/ksz_common.c
> @@ -2426,6 +2426,17 @@ static enum dsa_tag_protocol ksz_get_tag_protocol(struct dsa_switch *ds,
> return proto;
> }
>
> +static int ksz_connect_tag_protocol(struct dsa_switch *ds,
> + enum dsa_tag_protocol proto)
> +{
> + struct ksz_tagger_data *tagger_data;
> +
> + tagger_data = ksz_tagger_data(ds);
NULL pointer dereference is here:
ksz_connect() is only called for "lan937x", not for the other KSZ switches.
If ksz_connect() shall only be called for PTP switches, the result of
ksz_tagger_data() may be NULL.
> + tagger_data->meta_tstamp_handler = ksz_tstamp_reconstruct;
> +
> + return 0;
> +}
> +
> static int ksz_port_vlan_filtering(struct dsa_switch *ds, int port,
> bool flag, struct netlink_ext_ack *extack)
> {
> @@ -2819,6 +2830,7 @@ static int ksz_switch_detect(struct ksz_device *dev)
>
> static const struct dsa_switch_ops ksz_switch_ops = {
> .get_tag_protocol = ksz_get_tag_protocol,
> + .connect_tag_protocol = ksz_connect_tag_protocol,
> .get_phy_flags = ksz_get_phy_flags,
> .setup = ksz_setup,
> .teardown = ksz_teardown,
> diff --git a/drivers/net/dsa/microchip/ksz_ptp.c b/drivers/net/dsa/microchip/ksz_ptp.c
> index 2cae543f7e0b..5ae6eedb6b39 100644
> --- a/drivers/net/dsa/microchip/ksz_ptp.c
> +++ b/drivers/net/dsa/microchip/ksz_ptp.c
> @@ -372,6 +372,31 @@ static int ksz_ptp_start_clock(struct ksz_device *dev)
> return 0;
> }
>
> +ktime_t ksz_tstamp_reconstruct(struct dsa_switch *ds, ktime_t tstamp)
> +{
> + struct ksz_device *dev = ds->priv;
> + struct ksz_ptp_data *ptp_data = &dev->ptp_data;
> + struct timespec64 ts = ktime_to_timespec64(tstamp);
> + struct timespec64 ptp_clock_time;
> + struct timespec64 diff;
> +
> + spin_lock_bh(&ptp_data->clock_lock);
> + ptp_clock_time = ptp_data->clock_time;
> + spin_unlock_bh(&ptp_data->clock_lock);
> +
> + /* calculate full time from partial time stamp */
> + ts.tv_sec = (ptp_clock_time.tv_sec & ~3) | ts.tv_sec;
> +
> + /* find nearest possible point in time */
> + diff = timespec64_sub(ts, ptp_clock_time);
> + if (diff.tv_sec > 2)
> + ts.tv_sec -= 4;
> + else if (diff.tv_sec < -2)
> + ts.tv_sec += 4;
> +
> + return timespec64_to_ktime(ts);
> +}
> +
> static const struct ptp_clock_info ksz_ptp_caps = {
> .owner = THIS_MODULE,
> .name = "Microchip Clock",
> diff --git a/drivers/net/dsa/microchip/ksz_ptp.h b/drivers/net/dsa/microchip/ksz_ptp.h
> index 7e5d374d2acf..9589909ab7d5 100644
> --- a/drivers/net/dsa/microchip/ksz_ptp.h
> +++ b/drivers/net/dsa/microchip/ksz_ptp.h
> @@ -28,6 +28,7 @@ int ksz_hwtstamp_get(struct dsa_switch *ds, int port, struct ifreq *ifr);
> int ksz_hwtstamp_set(struct dsa_switch *ds, int port, struct ifreq *ifr);
> int ksz_ptp_irq_setup(struct dsa_switch *ds, u8 p);
> void ksz_ptp_irq_free(struct dsa_switch *ds, u8 p);
> +ktime_t ksz_tstamp_reconstruct(struct dsa_switch *ds, ktime_t tstamp);
>
> #else
>
> @@ -64,6 +65,11 @@ static inline int ksz_ptp_irq_setup(struct dsa_switch *ds, u8 p)
>
> static inline void ksz_ptp_irq_free(struct dsa_switch *ds, u8 p) {}
>
> +static inline ktime_t ksz_tstamp_reconstruct(struct dsa_switch *ds, ktime_t tstamp)
> +{
> + return 0;
> +}
> +
> #endif /* End of CONFIG_NET_DSA_MICROCHIOP_KSZ_PTP */
>
> #endif
> diff --git a/include/linux/dsa/ksz_common.h b/include/linux/dsa/ksz_common.h
> index 8903bce4753b..82edd7228b3c 100644
> --- a/include/linux/dsa/ksz_common.h
> +++ b/include/linux/dsa/ksz_common.h
> @@ -9,9 +9,24 @@
>
> #include <net/dsa.h>
>
> +/* All time stamps from the KSZ consist of 2 bits for seconds and 30 bits for
> + * nanoseconds. This is NOT the same as 32 bits for nanoseconds.
> + */
> +#define KSZ_TSTAMP_SEC_MASK GENMASK(31, 30)
> +#define KSZ_TSTAMP_NSEC_MASK GENMASK(29, 0)
> +
> +static inline ktime_t ksz_decode_tstamp(u32 tstamp)
> +{
> + u64 ns = FIELD_GET(KSZ_TSTAMP_SEC_MASK, tstamp) * NSEC_PER_SEC +
> + FIELD_GET(KSZ_TSTAMP_NSEC_MASK, tstamp);
> +
> + return ns_to_ktime(ns);
> +}
> +
> struct ksz_tagger_data {
> bool (*hwtstamp_get_state)(struct dsa_switch *ds);
> void (*hwtstamp_set_state)(struct dsa_switch *ds, bool on);
> + ktime_t (*meta_tstamp_handler)(struct dsa_switch *ds, ktime_t tstamp);
> };
>
> static inline struct ksz_tagger_data *
> diff --git a/net/dsa/tag_ksz.c b/net/dsa/tag_ksz.c
> index ca1261b04fe7..937a3e70b471 100644
> --- a/net/dsa/tag_ksz.c
> +++ b/net/dsa/tag_ksz.c
> @@ -164,6 +164,25 @@ MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_KSZ8795);
> #define KSZ9477_TAIL_TAG_OVERRIDE BIT(9)
> #define KSZ9477_TAIL_TAG_LOOKUP BIT(10)
>
> +static void ksz_rcv_timestamp(struct sk_buff *skb, u8 *tag,
> + struct net_device *dev, unsigned int port)
> +{
> + struct skb_shared_hwtstamps *hwtstamps = skb_hwtstamps(skb);
> + u8 *tstamp_raw = tag - KSZ9477_PTP_TAG_LEN;
> + struct dsa_switch *ds = dev->dsa_ptr->ds;
> + struct ksz_tagger_data *tagger_data;
> + ktime_t tstamp;
> +
> + tagger_data = ksz_tagger_data(ds);
another potential NULL pointer dereference here:
> + if (!tagger_data->meta_tstamp_handler)
> + return;
> +
> + /* convert time stamp and write to skb */
> + tstamp = ksz_decode_tstamp(get_unaligned_be32(tstamp_raw));
> + memset(hwtstamps, 0, sizeof(*hwtstamps));
> + hwtstamps->hwtstamp = tagger_data->meta_tstamp_handler(ds, tstamp);
> +}
> +
> static struct sk_buff *ksz9477_xmit(struct sk_buff *skb,
> struct net_device *dev)
> {
> @@ -197,8 +216,10 @@ static struct sk_buff *ksz9477_rcv(struct sk_buff *skb, struct net_device *dev)
> unsigned int len = KSZ_EGRESS_TAG_LEN;
>
> /* Extra 4-bytes PTP timestamp */
> - if (tag[0] & KSZ9477_PTP_TAG_INDICATION)
> + if (tag[0] & KSZ9477_PTP_TAG_INDICATION) {
> + ksz_rcv_timestamp(skb, tag, dev, port);
> len += KSZ9477_PTP_TAG_LEN;
> + }
>
> return ksz_common_rcv(skb, dev, port, len);
> }
> @@ -257,10 +278,11 @@ MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_KSZ9893);
> * tag0 : represents tag override, lookup and valid
> * tag1 : each bit represents port (eg, 0x01=port1, 0x02=port2, 0x80=port8)
> *
> - * For rcv, 1 byte is added before FCS.
> + * For rcv, 1/5 bytes is added before FCS.
> * ---------------------------------------------------------------------------
> - * DA(6bytes)|SA(6bytes)|....|Data(nbytes)|tag0(1byte)|FCS(4bytes)
> + * DA(6bytes)|SA(6bytes)|....|Data(nbytes)|ts(4bytes)|tag0(1byte)|FCS(4bytes)
> * ---------------------------------------------------------------------------
> + * ts : time stamp (Present only if bit 7 of tag0 is set)
> * tag0 : zero-based value represents port
> * (eg, 0x00=port1, 0x02=port3, 0x07=port8)
> */
> @@ -304,7 +326,7 @@ static const struct dsa_device_ops lan937x_netdev_ops = {
> .rcv = ksz9477_rcv,
> .connect = ksz_connect,
> .disconnect = ksz_disconnect,
> - .needed_tailroom = LAN937X_EGRESS_TAG_LEN,
> + .needed_tailroom = LAN937X_EGRESS_TAG_LEN + KSZ9477_PTP_TAG_LEN,
> };
>
> DSA_TAG_DRIVER(lan937x_netdev_ops);
>
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