From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexei Starovoitov Subject: [PATCH v7 tip 3/8] tracing: allow BPF programs to call bpf_ktime_get_ns() Date: Mon, 16 Mar 2015 14:49:39 -0700 Message-ID: <1426542584-9406-4-git-send-email-ast@plumgrid.com> References: <1426542584-9406-1-git-send-email-ast@plumgrid.com> Return-path: In-Reply-To: <1426542584-9406-1-git-send-email-ast@plumgrid.com> Sender: linux-kernel-owner@vger.kernel.org To: Ingo Molnar Cc: Steven Rostedt , Namhyung Kim , Arnaldo Carvalho de Melo , Jiri Olsa , Masami Hiramatsu , "David S. Miller" , Daniel Borkmann , Peter Zijlstra , linux-api@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-api@vger.kernel.org bpf_ktime_get_ns() is used by programs to compue time delta between events 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, + }, }; static const struct bpf_func_proto *kprobe_prog_func_proto(enum bpf_func_id func_id) -- 1.7.9.5