From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Rostedt Subject: Re: [PATCH v7 tip 3/8] tracing: allow BPF programs to call bpf_ktime_get_ns() Date: Thu, 19 Mar 2015 11:11:24 -0400 Message-ID: <20150319111124.38f53061@gandalf.local.home> References: <1426542584-9406-1-git-send-email-ast@plumgrid.com> <1426542584-9406-4-git-send-email-ast@plumgrid.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1426542584-9406-4-git-send-email-ast-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Alexei Starovoitov Cc: Ingo Molnar , Namhyung Kim , Arnaldo Carvalho de Melo , Jiri Olsa , Masami Hiramatsu , "David S. Miller" , Daniel Borkmann , Peter Zijlstra , linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-api@vger.kernel.org On Mon, 16 Mar 2015 14:49:39 -0700 Alexei Starovoitov 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 > --- > 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)