netdev - [PATCH bpf-next 01/10] bpf: add typecast to raw

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Message-ID: <20191005050314.1114330-2-ast@kernel.org>
Date:   Fri, 4 Oct 2019 22:03:05 -0700
From:   Alexei Starovoitov <ast@...nel.org>
To:     <davem@...emloft.net>
CC:     <daniel@...earbox.net>, <x86@...nel.org>, <netdev@...r.kernel.org>,
        <bpf@...r.kernel.org>, <kernel-team@...com>
Subject: [PATCH bpf-next 01/10] bpf: add typecast to raw_tracepoints to help BTF generation

When pahole converts dwarf to btf it emits only used types.
Wrap existing __bpf_trace_##template() function into
btf_trace_##template typedef and use it in type cast to
make gcc emits this type into dwarf. Then pahole will convert it to btf.
The "btf_trace_" prefix will be used to identify BTF enabled raw tracepoints.

Signed-off-by: Alexei Starovoitov <ast@...nel.org>
---
 include/trace/bpf_probe.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/trace/bpf_probe.h b/include/trace/bpf_probe.h
index d6e556c0a085..ff1a879773df 100644
--- a/include/trace/bpf_probe.h
+++ b/include/trace/bpf_probe.h
@@ -74,11 +74,12 @@ static inline void bpf_test_probe_##call(void)				\
 {									\
 	check_trace_callback_type_##call(__bpf_trace_##template);	\
 }									\
+typedef void (*btf_trace_##template)(void *__data, proto);		\
 static struct bpf_raw_event_map	__used					\
 	__attribute__((section("__bpf_raw_tp_map")))			\
 __bpf_trace_tp_map_##call = {						\
 	.tp		= &__tracepoint_##call,				\
-	.bpf_func	= (void *)__bpf_trace_##template,		\
+	.bpf_func	= (void *)(btf_trace_##template)__bpf_trace_##template,	\
 	.num_args	= COUNT_ARGS(args),				\
 	.writable_size	= size,						\
 };
-- 
2.20.0