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

Signed-off-by: Alexei Starovoitov <a...@plumgrid.com>
---
 include/uapi/linux/bpf.h |    1 +
 kernel/trace/bpf_trace.c |   10 ++++++++++
 2 files changed, 11 insertions(+)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index d73d7d0abe6e..ecae21e58ba3 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -169,6 +169,7 @@ enum bpf_func_id {
        BPF_FUNC_fetch_u16,       /* u16 bpf_fetch_u16(void *unsafe_ptr) */
        BPF_FUNC_fetch_u8,        /* u8 bpf_fetch_u8(void *unsafe_ptr) */
        BPF_FUNC_probe_memcmp,    /* int bpf_probe_memcmp(unsafe_ptr, safe_ptr, 
size) */
+       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 ec065e0a364e..e3196266b72f 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -69,6 +69,11 @@ static u64 bpf_probe_memcmp(u64 r1, u64 r2, u64 r3, u64 r4, 
u64 r5)
        return -1;
 }
 
+static u64 bpf_ktime_get_ns(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
+{
+       return ktime_get_ns();
+}
+
 static struct bpf_func_proto tp_prog_funcs[] = {
 #define FETCH(SIZE)                            \
        [BPF_FUNC_fetch_##SIZE] = {             \
@@ -90,6 +95,11 @@ static struct bpf_func_proto tp_prog_funcs[] = {
                .arg2_type = ARG_PTR_TO_STACK,
                .arg3_type = ARG_CONST_STACK_SIZE,
        },
+       [BPF_FUNC_ktime_get_ns] = {
+               .func = bpf_ktime_get_ns,
+               .gpl_only = true,
+               .ret_type = RET_INTEGER,
+       },
 };
 
 static const struct bpf_func_proto *tp_prog_func_proto(enum bpf_func_id 
func_id)
-- 
1.7.9.5

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