From bb8ffe61ea454a565e4fb1f450ef71237c9f032c Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Fri, 11 Feb 2022 21:57:32 -0800 Subject: bpftool: Add C++-specific open/load/etc skeleton wrappers Add C++-specific static methods for code-generated BPF skeleton for each skeleton operation: open, open_opts, open_and_load, load, attach, detach, destroy, and elf_bytes. This is to facilitate easier C++ templating on top of pure C BPF skeleton. In C, open/load/destroy/etc "methods" are of the form __() to avoid name collision with similar "methods" of other skeletons withint the same application. This works well, but is very inconvenient for C++ applications that would like to write generic (templated) wrappers around BPF skeleton to fit in with C++ code base and take advantage of destructors and other convenient C++ constructs. This patch makes it easier to build such generic templated wrappers by additionally defining C++ static methods for skeleton's struct with fixed names. This allows to refer to, say, open method as `T::open()` instead of having to somehow generate `T__open()` function call. Next patch adds an example template to test_cpp selftest to demonstrate how it's possible to have all the operations wrapped in a generic Skeleton type without explicitly passing function references. An example of generated declaration section without %1$s placeholders: #ifdef __cplusplus static struct test_attach_probe *open(const struct bpf_object_open_opts *opts = nullptr); static struct test_attach_probe *open_and_load(); static int load(struct test_attach_probe *skel); static int attach(struct test_attach_probe *skel); static void detach(struct test_attach_probe *skel); static void destroy(struct test_attach_probe *skel); static const void *elf_bytes(size_t *sz); #endif /* __cplusplus */ Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20220212055733.539056-2-andrii@kernel.org --- tools/bpf/bpftool/gen.c | 24 ++++++++++++++++++++++-- 1 file changed, 22 insertions(+), 2 deletions(-) (limited to 'tools/bpf/bpftool/gen.c') diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c index 6f2e20be0c62..022f30490567 100644 --- a/tools/bpf/bpftool/gen.c +++ b/tools/bpf/bpftool/gen.c @@ -831,6 +831,16 @@ static int do_skeleton(int argc, char **argv) codegen("\ \n\ + \n\ + #ifdef __cplusplus \n\ + static struct %1$s *open(const struct bpf_object_open_opts *opts = nullptr);\n\ + static struct %1$s *open_and_load(); \n\ + static int load(struct %1$s *skel); \n\ + static int attach(struct %1$s *skel); \n\ + static void detach(struct %1$s *skel); \n\ + static void destroy(struct %1$s *skel); \n\ + static const void *elf_bytes(size_t *sz); \n\ + #endif /* __cplusplus */ \n\ }; \n\ \n\ static void \n\ @@ -1025,9 +1035,19 @@ static int do_skeleton(int argc, char **argv) \"; \n\ } \n\ \n\ - #endif /* %s */ \n\ + #ifdef __cplusplus \n\ + struct %1$s *%1$s::open(const struct bpf_object_open_opts *opts) { return %1$s__open_opts(opts); }\n\ + struct %1$s *%1$s::open_and_load() { return %1$s__open_and_load(); } \n\ + int %1$s::load(struct %1$s *skel) { return %1$s__load(skel); } \n\ + int %1$s::attach(struct %1$s *skel) { return %1$s__attach(skel); } \n\ + void %1$s::detach(struct %1$s *skel) { %1$s__detach(skel); } \n\ + void %1$s::destroy(struct %1$s *skel) { %1$s__destroy(skel); } \n\ + const void *%1$s::elf_bytes(size_t *sz) { return %1$s__elf_bytes(sz); } \n\ + #endif /* __cplusplus */ \n\ + \n\ + #endif /* %2$s */ \n\ ", - header_guard); + obj_name, header_guard); err = 0; out: bpf_object__close(obj); -- cgit v1.2.3