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Subject[PATCH v3 linux-trace 2/8] tracing: allow eBPF programs to call ktime_get_ns()
Date
bpf_ktime_get_ns() is used by programs to compue time delta between events
or as a timestamp

Signed-off-by: Alexei Starovoitov <ast@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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