[PATCH v11 tip 4/9] tracing: allow BPF programs to call bpf_ktime_get_ns()
From: Alexei Starovoitov <hidden>
Date: 2015-03-25 19:49:45
Also in:
lkml, netdev
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [security & lsm] (security audit and enforcement using bpf), bpf [tracing], the rest, tracing · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, KP Singh, Matt Bobrowski, Song Liu, Linus Torvalds, Steven Rostedt, Masami Hiramatsu
bpf_ktime_get_ns() is used by programs to compute time delta between events or as a timestamp Signed-off-by: Alexei Starovoitov <redacted> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> --- include/uapi/linux/bpf.h | 1 + kernel/trace/bpf_trace.c | 14 ++++++++++++++ 2 files changed, 15 insertions(+)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index b2948feeb70b..238c6883877b 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 f1e87da91da3..8f5787294971 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c@@ -78,6 +78,18 @@ static const struct bpf_func_proto bpf_probe_read_proto = { .arg3_type = ARG_ANYTHING, }; +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 const struct bpf_func_proto bpf_ktime_get_ns_proto = { + .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) { switch (func_id) {
@@ -89,6 +101,8 @@ static const struct bpf_func_proto *kprobe_prog_func_proto(enum bpf_func_id func return &bpf_map_delete_elem_proto; case BPF_FUNC_probe_read: return &bpf_probe_read_proto; + case BPF_FUNC_ktime_get_ns: + return &bpf_ktime_get_ns_proto; default: return NULL; }
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1.7.9.5