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| author |   Jesper Dangaard Brouer <brouer@redhat.com> | 2022-08-09 08:08:02 +0200 |
|---|---|---|
| committer |   Alexei Starovoitov <ast@kernel.org> | 2022-08-09 09:47:13 -0700 |
| commit | c8996c98f703b09afe77a1d247dae691c9849dc1 (patch) | |
| tree | 84f0a854239e06f4a70ade64ff99b2242191b171 /include/uapi/linux/bpf.h | |
| parent | bpf: Cleanup check_refcount_ok (diff) | |
| download | linux-dev-c8996c98f703b09afe77a1d247dae691c9849dc1.tar.xz linux-dev-c8996c98f703b09afe77a1d247dae691c9849dc1.zip | |
bpf: Add BPF-helper for accessing CLOCK_TAI
Commit 3dc6ffae2da2 ("timekeeping: Introduce fast accessor to clock tai")
introduced a fast and NMI-safe accessor for CLOCK_TAI. Especially in time
sensitive networks (TSN), where all nodes are synchronized by Precision Time
Protocol (PTP), it's helpful to have the possibility to generate timestamps
based on CLOCK_TAI instead of CLOCK_MONOTONIC. With a BPF helper for TAI in
place, it becomes very convenient to correlate activity across different
machines in the network.
Use cases for such a BPF helper include functionalities such as Tx launch
time (e.g. ETF and TAPRIO Qdiscs) and timestamping.
Note: CLOCK_TAI is nothing new per se, only the NMI-safe variant of it is.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
[Kurt: Wrote changelog and renamed helper]
Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
Link: https://lore.kernel.org/r/20220809060803.5773-2-kurt@linutronix.de
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'include/uapi/linux/bpf.h')
| -rw-r--r-- | include/uapi/linux/bpf.h | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 534e33fb1029..7d1e2794d83e 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -5341,6 +5341,18 @@ union bpf_attr { * **-EACCES** if the SYN cookie is not valid. * * **-EPROTONOSUPPORT** if CONFIG_IPV6 is not builtin. + * + * u64 bpf_ktime_get_tai_ns(void) + * Description + * A nonsettable system-wide clock derived from wall-clock time but + * ignoring leap seconds. This clock does not experience + * discontinuities and backwards jumps caused by NTP inserting leap + * seconds as CLOCK_REALTIME does. + * + * See: **clock_gettime**\ (**CLOCK_TAI**) + * Return + * Current *ktime*. + * */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -5551,6 +5563,7 @@ union bpf_attr { FN(tcp_raw_gen_syncookie_ipv6), \ FN(tcp_raw_check_syncookie_ipv4), \ FN(tcp_raw_check_syncookie_ipv6), \ + FN(ktime_get_tai_ns), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper |