On Mon, 16 Mar 2015 14:49:39 -0700
Alexei Starovoitov <ast@xxxxxxxxxxxx> wrote:
> bpf_ktime_get_ns() is used by programs to compue time delta between events
"compute"
> or as a timestamp
>
> Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxxxx>
> ---
> include/uapi/linux/bpf.h | 1 +
> kernel/trace/bpf_trace.c | 11 +++++++++++
> 2 files changed, 12 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 ba95b131082c..74eb6abda6a1 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -56,6 +56,12 @@ 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)
> +{
> + /* NMI safe access to clock monotonic */
> + return ktime_get_mono_fast_ns();
> +}
> +
> static struct bpf_func_proto kprobe_prog_funcs[] = {
> [BPF_FUNC_probe_read] = {
> .func = bpf_probe_read,
> @@ -65,6 +71,11 @@ static struct bpf_func_proto kprobe_prog_funcs[] = {
> .arg2_type = ARG_CONST_STACK_SIZE,
> .arg3_type = ARG_ANYTHING,
> },
> + [BPF_FUNC_ktime_get_ns] = {
> + .func = bpf_ktime_get_ns,
> + .gpl_only = true,
> + .ret_type = RET_INTEGER,
Hmm, a nanosecond value returned as integer? Is there a way to make
this a 64 bit return type, or is RET_INTEGER default to 64 bits in BPF
functions?
-- Steve
> + },
> };
>
> static const struct bpf_func_proto *kprobe_prog_func_proto(enum bpf_func_id func_id)
--
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