Commit c975d94a authored by Daniel Borkmann's avatar Daniel Borkmann
Browse files

Merge branch 'bpf-drop-libbpf-from-preload' 



Alexei Starovoitov says:

====================
CO-RE in the kernel support allows bpf preload to switch to light
skeleton and remove libbpf dependency.

This reduces the size of bpf_preload_umd from 300kbyte to 19kbyte
and eventually will make "kernel skeleton" possible.
====================

Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parents 533de4ae e96f2d64

kernel/bpf/preload/Makefile

+2 −26
Original line number Diff line number Diff line 
# SPDX-License-Identifier: GPL-2.0



LIBBPF_SRCS = $(srctree)/tools/lib/bpf/

LIBBPF_OUT = $(abspath $(obj))/libbpf

LIBBPF_A = $(LIBBPF_OUT)/libbpf.a

LIBBPF_DESTDIR = $(LIBBPF_OUT)

LIBBPF_INCLUDE = $(LIBBPF_DESTDIR)/include



# Although not in use by libbpf's Makefile, set $(O) so that the "dummy" test

# in tools/scripts/Makefile.include always succeeds when building the kernel

# with $(O) pointing to a relative path, as in "make O=build bindeb-pkg".

$(LIBBPF_A): | $(LIBBPF_OUT)

	$(Q)$(MAKE) -C $(LIBBPF_SRCS) O=$(LIBBPF_OUT)/ OUTPUT=$(LIBBPF_OUT)/   \

		DESTDIR=$(LIBBPF_DESTDIR) prefix=			       \

		$(LIBBPF_OUT)/libbpf.a install_headers



libbpf_hdrs: $(LIBBPF_A)



.PHONY: libbpf_hdrs



$(LIBBPF_OUT):

	$(call msg,MKDIR,$@)

	$(Q)mkdir -p $@

LIBBPF_INCLUDE = $(LIBBPF_SRCS)/..



userccflags += -I $(srctree)/tools/include/ -I $(srctree)/tools/include/uapi \

	-I $(LIBBPF_INCLUDE) -Wno-unused-result



userprogs := bpf_preload_umd



clean-files := libbpf/



$(obj)/iterators/iterators.o: | libbpf_hdrs



bpf_preload_umd-objs := iterators/iterators.o

bpf_preload_umd-userldlibs := $(LIBBPF_A) -lelf -lz



$(obj)/bpf_preload_umd: $(LIBBPF_A)

$(obj)/bpf_preload_umd:



$(obj)/bpf_preload_umd_blob.o: $(obj)/bpf_preload_umd

kernel/bpf/preload/iterators/Makefile

+3 −3
Original line number Diff line number Diff line
@@ -35,15 +35,15 @@ endif 


.PHONY: all clean



all: iterators.skel.h

all: iterators.lskel.h



clean:

	$(call msg,CLEAN)

	$(Q)rm -rf $(OUTPUT) iterators



iterators.skel.h: $(OUTPUT)/iterators.bpf.o | $(BPFTOOL)

iterators.lskel.h: $(OUTPUT)/iterators.bpf.o | $(BPFTOOL)

	$(call msg,GEN-SKEL,$@)

	$(Q)$(BPFTOOL) gen skeleton $< > $@

	$(Q)$(BPFTOOL) gen skeleton -L $< > $@





$(OUTPUT)/iterators.bpf.o: iterators.bpf.c $(BPFOBJ) | $(OUTPUT)

kernel/bpf/preload/iterators/iterators.c

+21 −7
Original line number Diff line number Diff line
@@ -10,20 +10,36 @@ 
#include <bpf/libbpf.h>

#include <bpf/bpf.h>

#include <sys/mount.h>

#include "iterators.skel.h"

#include "iterators.lskel.h"

#include "bpf_preload_common.h"



int to_kernel = -1;

int from_kernel = 0;



static int send_link_to_kernel(struct bpf_link *link, const char *link_name)

static int __bpf_obj_get_info_by_fd(int bpf_fd, void *info, __u32 *info_len)

{

	union bpf_attr attr;

	int err;



	memset(&attr, 0, sizeof(attr));

	attr.info.bpf_fd = bpf_fd;

	attr.info.info_len = *info_len;

	attr.info.info = (long) info;



	err = skel_sys_bpf(BPF_OBJ_GET_INFO_BY_FD, &attr, sizeof(attr));

	if (!err)

		*info_len = attr.info.info_len;

	return err;

}



static int send_link_to_kernel(int link_fd, const char *link_name)

{

	struct bpf_preload_info obj = {};

	struct bpf_link_info info = {};

	__u32 info_len = sizeof(info);

	int err;



	err = bpf_obj_get_info_by_fd(bpf_link__fd(link), &info, &info_len);

	err = __bpf_obj_get_info_by_fd(link_fd, &info, &info_len);

	if (err)

		return err;

	obj.link_id = info.id;
@@ -37,7 +53,6 @@ static int send_link_to_kernel(struct bpf_link *link, const char *link_name) 


int main(int argc, char **argv)

{

	struct rlimit rlim = { RLIM_INFINITY, RLIM_INFINITY };

	struct iterators_bpf *skel;

	int err, magic;

	int debug_fd;
@@ -55,7 +70,6 @@ int main(int argc, char **argv) 
		printf("bad start magic %d\n", magic);

		return 1;

	}

	setrlimit(RLIMIT_MEMLOCK, &rlim);

	/* libbpf opens BPF object and loads it into the kernel */

	skel = iterators_bpf__open_and_load();

	if (!skel) {
@@ -72,10 +86,10 @@ int main(int argc, char **argv) 
		goto cleanup;



	/* send two bpf_link IDs with names to the kernel */

	err = send_link_to_kernel(skel->links.dump_bpf_map, "maps.debug");

	err = send_link_to_kernel(skel->links.dump_bpf_map_fd, "maps.debug");

	if (err)

		goto cleanup;

	err = send_link_to_kernel(skel->links.dump_bpf_prog, "progs.debug");

	err = send_link_to_kernel(skel->links.dump_bpf_prog_fd, "progs.debug");

	if (err)

		goto cleanup;

kernel/bpf/preload/iterators/iterators.lskel.h

0 → 100644
+428 −0

File added.

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kernel/bpf/preload/iterators/iterators.skel.h

deleted100644 → 0
+0 −412

File deleted.

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