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Commit d9847d31 authored by Alexei Starovoitov's avatar Alexei Starovoitov Committed by Ingo Molnar
Browse files

tracing: Allow BPF programs to call bpf_ktime_get_ns() 



bpf_ktime_get_ns() is used by programs to compute time delta
between events or as a timestamp

Signed-off-by: default avatarAlexei Starovoitov <ast@plumgrid.com>
Reviewed-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David S. Miller <davem@davemloft.net>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1427312966-8434-5-git-send-email-ast@plumgrid.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 2541517c

include/uapi/linux/bpf.h

+1 −0
Original line number Diff line number Diff line
@@ -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,

};

kernel/trace/bpf_trace.c

+14 −0
Original line number Diff line number Diff line
@@ -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;

	}