linux/tools
Martin KaFai Lau 8d21ec0e46 bpf: Add __sk_buff->delivery_time_type and bpf_skb_set_skb_delivery_time()
* __sk_buff->delivery_time_type:
This patch adds __sk_buff->delivery_time_type.  It tells if the
delivery_time is stored in __sk_buff->tstamp or not.

It will be most useful for ingress to tell if the __sk_buff->tstamp
has the (rcv) timestamp or delivery_time.  If delivery_time_type
is 0 (BPF_SKB_DELIVERY_TIME_NONE), it has the (rcv) timestamp.

Two non-zero types are defined for the delivery_time_type,
BPF_SKB_DELIVERY_TIME_MONO and BPF_SKB_DELIVERY_TIME_UNSPEC.  For UNSPEC,
it can only happen in egress because only mono delivery_time can be
forwarded to ingress now.  The clock of UNSPEC delivery_time
can be deduced from the skb->sk->sk_clockid which is how
the sch_etf doing it also.

* Provide forwarded delivery_time to tc-bpf@ingress:
With the help of the new delivery_time_type, the tc-bpf has a way
to tell if the __sk_buff->tstamp has the (rcv) timestamp or
the delivery_time.  During bpf load time, the verifier will learn if
the bpf prog has accessed the new __sk_buff->delivery_time_type.
If it does, it means the tc-bpf@ingress is expecting the
skb->tstamp could have the delivery_time.  The kernel will then
read the skb->tstamp as-is during bpf insn rewrite without
checking the skb->mono_delivery_time.  This is done by adding a
new prog->delivery_time_access bit.  The same goes for
writing skb->tstamp.

* bpf_skb_set_delivery_time():
The bpf_skb_set_delivery_time() helper is added to allow setting both
delivery_time and the delivery_time_type at the same time.  If the
tc-bpf does not need to change the delivery_time_type, it can directly
write to the __sk_buff->tstamp as the existing tc-bpf has already been
doing.  It will be most useful at ingress to change the
__sk_buff->tstamp from the (rcv) timestamp to
a mono delivery_time and then bpf_redirect_*().

bpf only has mono clock helper (bpf_ktime_get_ns), and
the current known use case is the mono EDT for fq, and
only mono delivery time can be kept during forward now,
so bpf_skb_set_delivery_time() only supports setting
BPF_SKB_DELIVERY_TIME_MONO.  It can be extended later when use cases
come up and the forwarding path also supports other clock bases.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2022-03-03 14:38:49 +00:00
..
accounting delayacct: track delays from memory compact 2022-01-20 08:52:55 +02:00
arch tools headers cpufeatures: Sync with the kernel sources 2022-02-01 12:21:47 -03:00
bootconfig
bpf bpftool: Fix C++ additions to skeleton 2022-02-16 16:58:51 -08:00
build Merge remote-tracking branch 'torvalds/master' into perf/core 2022-01-13 10:20:59 -03:00
cgroup tools/cgroup/slabinfo: update to work with struct slab 2022-02-21 11:34:49 +01:00
counter
debugging
edid
firewire
firmware
gpio
hv
iio iio: event_monitor: Flush output on event 2021-12-16 12:20:35 +00:00
include bpf: Add __sk_buff->delivery_time_type and bpf_skb_set_skb_delivery_time() 2022-03-03 14:38:49 +00:00
io_uring
kvm/kvm_stat
laptop
leds
lib Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2022-02-17 17:23:52 -08:00
memory-model
objtool objtool: Fix truncated string warning 2022-01-24 10:09:06 -08:00
pci
pcmcia
perf Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-02-17 11:44:20 -08:00
power More ACPI updates for 5.17-rc1 2022-01-18 08:51:51 +02:00
rcu
scripts tools: Ignore errors from `which' when searching a GCC toolchain 2022-02-01 23:04:12 +01:00
spi
testing selftests: forwarding: hw_stats_l3: Add a new test 2022-03-03 10:37:23 +00:00
thermal/tmon
time
tracing rtla: Fix segmentation fault when failing to enable -t 2022-02-08 11:23:09 -05:00
usb
virtio
vm
wmi
Makefile