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Commit 8c4905b9 authored by Stanislav Fomichev's avatar Stanislav Fomichev Committed by Daniel Borkmann
Browse files

libbpf: make sure bpf headers are c++ include-able 



Wrap headers in extern "C", to turn off C++ mangling.
This simplifies including libbpf in c++ and linking against it.

v2 changes:
* do the same for btf.h

v3 changes:
* test_libbpf.cpp to test for possible future c++ breakages

Signed-off-by: default avatarStanislav Fomichev <sdf@google.com>
Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent 462c124c

tools/lib/bpf/Makefile

+12 −3
Original line number Diff line number Diff line
@@ -66,7 +66,7 @@ ifndef VERBOSE 
endif



FEATURE_USER = .libbpf

FEATURE_TESTS = libelf libelf-mmap bpf reallocarray

FEATURE_TESTS = libelf libelf-mmap bpf reallocarray cxx

FEATURE_DISPLAY = libelf bpf



INCLUDES = -I. -I$(srctree)/tools/include -I$(srctree)/tools/arch/$(ARCH)/include/uapi -I$(srctree)/tools/include/uapi
@@ -148,6 +148,12 @@ LIB_FILE := $(addprefix $(OUTPUT),$(LIB_FILE)) 


CMD_TARGETS = $(LIB_FILE)



CXX_TEST_TARGET = $(OUTPUT)test_libbpf



ifeq ($(feature-cxx), 1)

	CMD_TARGETS += $(CXX_TEST_TARGET)

endif



TARGETS = $(CMD_TARGETS)



all: fixdep all_cmd
@@ -175,6 +181,9 @@ $(OUTPUT)libbpf.so: $(BPF_IN) 
$(OUTPUT)libbpf.a: $(BPF_IN)

	$(QUIET_LINK)$(RM) $@; $(AR) rcs $@ $^



$(OUTPUT)test_libbpf: test_libbpf.cpp $(OUTPUT)libbpf.a

	$(QUIET_LINK)$(CXX) $^ -lelf -o $@



define do_install

	if [ ! -d '$(DESTDIR_SQ)$2' ]; then		\

		$(INSTALL) -d -m 755 '$(DESTDIR_SQ)$2';	\
@@ -201,8 +210,8 @@ config-clean: 
	$(Q)$(MAKE) -C $(srctree)/tools/build/feature/ clean >/dev/null



clean:

	$(call QUIET_CLEAN, libbpf) $(RM) *.o *~ $(TARGETS) *.a *.so .*.d .*.cmd \

		$(RM) LIBBPF-CFLAGS

	$(call QUIET_CLEAN, libbpf) $(RM) $(TARGETS) $(CXX_TEST_TARGET) \

		*.o *~ *.a *.so .*.d .*.cmd LIBBPF-CFLAGS

	$(call QUIET_CLEAN, core-gen) $(RM) $(OUTPUT)FEATURE-DUMP.libbpf

tools/lib/bpf/bpf.h

+9 −0
Original line number Diff line number Diff line
@@ -27,6 +27,10 @@ 
#include <stdbool.h>

#include <stddef.h>



#ifdef __cplusplus

extern "C" {

#endif



#ifndef LIBBPF_API

#define LIBBPF_API __attribute__((visibility("default")))

#endif
@@ -132,4 +136,9 @@ LIBBPF_API int bpf_load_btf(void *btf, __u32 btf_size, char *log_buf, 
LIBBPF_API int bpf_task_fd_query(int pid, int fd, __u32 flags, char *buf,

				 __u32 *buf_len, __u32 *prog_id, __u32 *fd_type,

				 __u64 *probe_offset, __u64 *probe_addr);



#ifdef __cplusplus

} /* extern "C" */

#endif



#endif /* __LIBBPF_BPF_H */

tools/lib/bpf/btf.h

+8 −0
Original line number Diff line number Diff line
@@ -6,6 +6,10 @@ 


#include <linux/types.h>



#ifdef __cplusplus

extern "C" {

#endif



#ifndef LIBBPF_API

#define LIBBPF_API __attribute__((visibility("default")))

#endif
@@ -80,4 +84,8 @@ int btf_ext__reloc(struct btf *btf, struct btf_ext *btf_ext, 
		   const char *sec_name, __u32 insns_cnt, void **func_info,

		   __u32 *func_info_len);



#ifdef __cplusplus

} /* extern "C" */

#endif



#endif /* __LIBBPF_BTF_H */

tools/lib/bpf/libbpf.h

+9 −0
Original line number Diff line number Diff line
@@ -16,6 +16,10 @@ 
#include <sys/types.h>  // for size_t

#include <linux/bpf.h>



#ifdef __cplusplus

extern "C" {

#endif



#ifndef LIBBPF_API

#define LIBBPF_API __attribute__((visibility("default")))

#endif
@@ -335,4 +339,9 @@ int libbpf_nl_get_qdisc(int sock, unsigned int nl_pid, int ifindex, 
			libbpf_dump_nlmsg_t dump_qdisc_nlmsg, void *cookie);

int libbpf_nl_get_filter(int sock, unsigned int nl_pid, int ifindex, int handle,

			 libbpf_dump_nlmsg_t dump_filter_nlmsg, void *cookie);



#ifdef __cplusplus

} /* extern "C" */

#endif



#endif /* __LIBBPF_LIBBPF_H */

tools/lib/bpf/test_libbpf.cpp

0 → 100644
+18 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */

#include "libbpf.h"

#include "bpf.h"

#include "btf.h"



/* do nothing, just make sure we can link successfully */



int main(int argc, char *argv[])

{

    /* libbpf.h */

    libbpf_set_print(NULL, NULL, NULL);



    /* bpf.h */

    bpf_prog_get_fd_by_id(0);



    /* btf.h */

    btf__new(NULL, 0, NULL);

}