On Fri, Feb 27, 2015 at 04:08:51PM -0800, Alexei Starovoitov wrote:
> bpf_ktime_get_ns() is used by programs to compue time delta between events
> or as a timestamp
>
> Signed-off-by: Alexei Starovoitov <a...@plumgrid.com>
> ---
> include/uapi/linux/bpf.h | 1 +
> kernel/trace/bpf_trace.c | 10 ++++++++++
> 2 files changed, 11 insertions(+)
>
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 4486d36d2e9e..101e509d1001 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -165,6 +165,7 @@ enum bpf_func_id {
> BPF_FUNC_map_update_elem, /* int map_update_elem(&map, &key, &value,
> flags) */
> BPF_FUNC_map_delete_elem, /* int map_delete_elem(&map, &key) */
> BPF_FUNC_probe_read, /* int bpf_probe_read(void *dst, int size,
> void *src) */
> + BPF_FUNC_ktime_get_ns, /* u64 bpf_ktime_get_ns(void) */
> __BPF_FUNC_MAX_ID,
> };
>
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index bcce9b238dad..64b918488607 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -36,6 +36,11 @@ static u64 bpf_probe_read(u64 r1, u64 r2, u64 r3, u64 r4,
> u64 r5)
> return probe_kernel_read(dst, unsafe_ptr, size);
> }
>
> +static u64 bpf_ktime_get_ns(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
> +{
> + return ktime_get_ns();
> +}
Please use ktime_get_mono_fast_ns() instead. If you ever want to allow
running BPF stuff from general tracepoints and the like you need to
be NMI safe.
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