Commit c2a0257c authored by Kui-Feng Lee's avatar Kui-Feng Lee Committed by Andrii Nakryiko
Browse files

bpftool: Cast pointers for shadow types explicitly. 



According to a report, skeletons fail to assign shadow pointers when being
compiled with C++ programs. Unlike C doing implicit casting for void
pointers, C++ requires an explicit casting.

To support C++, we do explicit casting for each shadow pointer.

Also add struct_ops_module.skel.h to test_cpp to validate C++
compilation as part of BPF selftests.

Signed-off-by: default avatarKui-Feng Lee <thinker.li@gmail.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Acked-by: default avatarYonghong Song <yonghong.song@linux.dev>
Acked-by: default avatarQuentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20240312013726.1780720-1-thinker.li@gmail.com
parent 9187210e

tools/bpf/bpftool/gen.c

+2 −1
Original line number Diff line number Diff line
@@ -1131,7 +1131,8 @@ static void gen_st_ops_shadow_init(struct btf *btf, struct bpf_object *obj) 
			continue;

		codegen("\

			\n\

				obj->struct_ops.%1$s = bpf_map__initial_value(obj->maps.%1$s, NULL);\n\

				obj->struct_ops.%1$s = (typeof(obj->struct_ops.%1$s))\n\

					bpf_map__initial_value(obj->maps.%1$s, NULL);\n\

			\n\

			", ident);

	}

tools/testing/selftests/bpf/test_cpp.cpp

+5 −0
Original line number Diff line number Diff line
@@ -7,6 +7,7 @@ 
#include <bpf/bpf.h>

#include <bpf/btf.h>

#include "test_core_extern.skel.h"

#include "struct_ops_module.skel.h"



template <typename T>

class Skeleton {
@@ -98,6 +99,7 @@ int main(int argc, char *argv[]) 
{

	struct btf_dump_opts opts = { };

	struct test_core_extern *skel;

	struct struct_ops_module *skel2;

	struct btf *btf;

	int fd;
@@ -118,6 +120,9 @@ int main(int argc, char *argv[]) 
	skel = test_core_extern__open_and_load();

	test_core_extern__destroy(skel);



	skel2 = struct_ops_module__open_and_load();

	struct_ops_module__destroy(skel2);



	fd = bpf_enable_stats(BPF_STATS_RUN_TIME);

	if (fd < 0)

		std::cout << "FAILED to enable stats: " << fd << std::endl;