bpf: add bpf_ktime_get_boot_ns()

On a device like a cellphone which is constantly suspending
and resuming CLOCK_MONOTONIC is not particularly useful for
keeping track of or reacting to external network events.
Instead you want to use CLOCK_BOOTTIME.

Hence add bpf_ktime_get_boot_ns() as a mirror of bpf_ktime_get_ns()
based around CLOCK_BOOTTIME instead of CLOCK_MONOTONIC.

Signed-off-by: Maciej Żenczykowski <maze@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Maciej Żenczykowski 2020-04-26 09:15:25 -07:00 committed by Andrii Nakryiko
parent ba344d9494
commit 625f64a126

View File

@ -652,6 +652,8 @@ union bpf_attr {
* u64 bpf_ktime_get_ns(void)
* Description
* Return the time elapsed since system boot, in nanoseconds.
* Does not include time the system was suspended.
* See: clock_gettime(CLOCK_MONOTONIC)
* Return
* Current *ktime*.
*
@ -3025,6 +3027,14 @@ union bpf_attr {
* * **-EOPNOTSUPP** Unsupported operation, for example a
* call from outside of TC ingress.
* * **-ESOCKTNOSUPPORT** Socket type not supported (reuseport).
*
* u64 bpf_ktime_get_boot_ns(void)
* Description
* Return the time elapsed since system boot, in nanoseconds.
* Does include the time the system was suspended.
* See: clock_gettime(CLOCK_BOOTTIME)
* Return
* Current *ktime*.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@ -3151,7 +3161,8 @@ union bpf_attr {
FN(xdp_output), \
FN(get_netns_cookie), \
FN(get_current_ancestor_cgroup_id), \
FN(sk_assign),
FN(sk_assign), \
FN(ktime_get_boot_ns),
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
* function eBPF program intends to call