[PATCH v5 tip 3/7] tracing: allow BPF programs to call bpf_ktime_get_ns()
From: Alexei Starovoitov <hidden>
Date: 2015-03-01 23:29:56
Also in:
linux-api, lkml
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 compue time delta between events or as a timestamp Signed-off-by: Alexei Starovoitov <redacted> --- 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 bcce9b238dad..aa48b85cadb6 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c@@ -36,6 +36,12 @@ 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,
@@ -45,6 +51,11 @@ 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