[RFC PATCH 03/11] bpf: export proto for bpf_perf_event_output helper

[Kris Van Hees <kris.van.hees@oracle.com>]

The bpf_perf_event_output helper is used by various tracer BPF program
types, but it was not visible outside of bpf_trace.c.  In order to make
it available to tracer BPF program types that are implemented elsewhere,
a function is added similar to bpf_get_trace_printk_proto() to query the
prototype (bpf_get_perf_event_output_proto()).

Signed-off-by: Kris Van Hees <kris.van.hees@oracle.com>
Reviewed-by: Nick Alcock <nick.alcock@oracle.com>
---
 include/linux/bpf.h      | 1 +
 kernel/trace/bpf_trace.c | 6 ++++++
 2 files changed, 7 insertions(+)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 7a40a3cd7ff2..e4bcb79656c4 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -479,6 +479,7 @@ bool bpf_prog_array_compatible(struct bpf_array *array, const struct bpf_prog *f
 int bpf_prog_calc_tag(struct bpf_prog *fp);
 
 const struct bpf_func_proto *bpf_get_trace_printk_proto(void);
+const struct bpf_func_proto *bpf_get_perf_event_output_proto(void);
 
 typedef unsigned long (*bpf_ctx_copy_t)(void *dst, const void *src,
 					unsigned long off, unsigned long len);
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index b496ffdf5f36..3d812238bc40 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -473,6 +473,12 @@ static const struct bpf_func_proto bpf_perf_event_output_proto = {
 	.arg5_type	= ARG_CONST_SIZE_OR_ZERO,
 };
 
+const struct bpf_func_proto *bpf_get_perf_event_output_proto(void)
+{
+	return &bpf_perf_event_output_proto;
+}
+
+
 static DEFINE_PER_CPU(struct pt_regs, bpf_pt_regs);
 static DEFINE_PER_CPU(struct perf_sample_data, bpf_misc_sd);
 
-- 
2.20.1