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Commit 1b76c13e authored by Wang Nan's avatar Wang Nan Committed by Arnaldo Carvalho de Melo
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bpf tools: Introduce 'bpf' library and add bpf feature check 



This is the first patch of libbpf. The goal of libbpf is to create a
standard way for accessing eBPF object files. This patch creates
'Makefile' and 'Build' for it, allows 'make' to build libbpf.a and
libbpf.so, 'make install' to put them into proper directories.
Most part of Makefile is borrowed from traceevent.

Before building, it checks the existence of libelf in Makefile, and deny
to build if not found. Instead of throwing an error if libelf not found,
the error raises in a phony target "elfdep". This design is to ensure
'make clean' still workable even if libelf is not found.

Because libbpf requires 'kern_version' field set for 'union bpf_attr'
(bpfdep" is used for that dependency), Kernel BPF API is also checked
by intruducing a new feature check 'bpf' into tools/build/feature,
which checks the existence and version of linux/bpf.h. When building
libbpf, it searches that file from include/uapi/linux in kernel source
tree (controlled by FEATURE_CHECK_CFLAGS-bpf). Since it searches kernel
source tree it reside, installing of newest kernel headers is not
required, except we are trying to port these files to an old kernel.

To avoid checking that file when perf building, the newly introduced
'bpf' feature check doesn't added into FEATURE_TESTS and
FEATURE_DISPLAY by default in tools/build/Makefile.feature, but added
into libbpf's specific.

Signed-off-by: default avatarWang Nan <wangnan0@huawei.com>
Acked-by: default avatarAlexei Starovoitov <ast@plumgrid.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David Ahern <dsahern@gmail.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kaixu Xia <xiakaixu@huawei.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Zefan Li <lizefan@huawei.com>
Bcc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1435716878-189507-4-git-send-email-wangnan0@huawei.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 1354ac6a

tools/build/feature/Makefile

+5 −1
Original line number Diff line number Diff line
@@ -33,7 +33,8 @@ FILES= \ 
	test-compile-32.bin		\

	test-compile-x32.bin		\

	test-zlib.bin			\

	test-lzma.bin

	test-lzma.bin			\

	test-bpf.bin



CC := $(CROSS_COMPILE)gcc -MD

PKG_CONFIG := $(CROSS_COMPILE)pkg-config
@@ -156,6 +157,9 @@ test-zlib.bin: 
test-lzma.bin:

	$(BUILD) -llzma



test-bpf.bin:

	$(BUILD)



-include *.d



###############################

tools/build/feature/test-bpf.c

0 → 100644
+18 −0
Original line number Diff line number Diff line 
#include <linux/bpf.h>



int main(void)

{

	union bpf_attr attr;



	attr.prog_type = BPF_PROG_TYPE_KPROBE;

	attr.insn_cnt = 0;

	attr.insns = 0;

	attr.license = 0;

	attr.log_buf = 0;

	attr.log_size = 0;

	attr.log_level = 0;

	attr.kern_version = 0;



	attr = attr;

	return 0;

}

tools/lib/bpf/.gitignore

0 → 100644
+2 −0
Original line number Diff line number Diff line 
libbpf_version.h

FEATURE-DUMP

tools/lib/bpf/Build

0 → 100644
+1 −0
Original line number Diff line number Diff line 
libbpf-y := libbpf.o

tools/lib/bpf/Makefile

0 → 100644
+195 −0
Original line number Diff line number Diff line 
# Most of this file is copied from tools/lib/traceevent/Makefile



BPF_VERSION = 0

BPF_PATCHLEVEL = 0

BPF_EXTRAVERSION = 1



MAKEFLAGS += --no-print-directory





# Makefiles suck: This macro sets a default value of $(2) for the

# variable named by $(1), unless the variable has been set by

# environment or command line. This is necessary for CC and AR

# because make sets default values, so the simpler ?= approach

# won't work as expected.

define allow-override

  $(if $(or $(findstring environment,$(origin $(1))),\

            $(findstring command line,$(origin $(1)))),,\

    $(eval $(1) = $(2)))

endef



# Allow setting CC and AR, or setting CROSS_COMPILE as a prefix.

$(call allow-override,CC,$(CROSS_COMPILE)gcc)

$(call allow-override,AR,$(CROSS_COMPILE)ar)



INSTALL = install



# Use DESTDIR for installing into a different root directory.

# This is useful for building a package. The program will be

# installed in this directory as if it was the root directory.

# Then the build tool can move it later.

DESTDIR ?=

DESTDIR_SQ = '$(subst ','\'',$(DESTDIR))'



LP64 := $(shell echo __LP64__ | ${CC} ${CFLAGS} -E -x c - | tail -n 1)

ifeq ($(LP64), 1)

  libdir_relative = lib64

else

  libdir_relative = lib

endif



prefix ?= /usr/local

libdir = $(prefix)/$(libdir_relative)

man_dir = $(prefix)/share/man

man_dir_SQ = '$(subst ','\'',$(man_dir))'



export man_dir man_dir_SQ INSTALL

export DESTDIR DESTDIR_SQ



include ../../scripts/Makefile.include



# copy a bit from Linux kbuild



ifeq ("$(origin V)", "command line")

  VERBOSE = $(V)

endif

ifndef VERBOSE

  VERBOSE = 0

endif



ifeq ($(srctree),)

srctree := $(patsubst %/,%,$(dir $(shell pwd)))

srctree := $(patsubst %/,%,$(dir $(srctree)))

srctree := $(patsubst %/,%,$(dir $(srctree)))

#$(info Determined 'srctree' to be $(srctree))

endif



FEATURE_DISPLAY = libelf libelf-getphdrnum libelf-mmap bpf

FEATURE_TESTS = libelf bpf



INCLUDES = -I. -I$(srctree)/tools/include -I$(srctree)/arch/$(ARCH)/include/uapi -I$(srctree)/include/uapi

FEATURE_CHECK_CFLAGS-bpf = $(INCLUDES)



include $(srctree)/tools/build/Makefile.feature



export prefix libdir src obj



# Shell quotes

libdir_SQ = $(subst ','\'',$(libdir))

libdir_relative_SQ = $(subst ','\'',$(libdir_relative))

plugin_dir_SQ = $(subst ','\'',$(plugin_dir))



LIB_FILE = libbpf.a libbpf.so



VERSION		= $(BPF_VERSION)

PATCHLEVEL	= $(BPF_PATCHLEVEL)

EXTRAVERSION	= $(BPF_EXTRAVERSION)



OBJ		= $@

N		=



LIBBPF_VERSION = $(BPF_VERSION).$(BPF_PATCHLEVEL).$(BPF_EXTRAVERSION)



# Set compile option CFLAGS

ifdef EXTRA_CFLAGS

  CFLAGS := $(EXTRA_CFLAGS)

else

  CFLAGS := -g -Wall

endif



ifeq ($(feature-libelf-mmap), 1)

  override CFLAGS += -DHAVE_LIBELF_MMAP_SUPPORT

endif



ifeq ($(feature-libelf-getphdrnum), 1)

  override CFLAGS += -DHAVE_ELF_GETPHDRNUM_SUPPORT

endif



# Append required CFLAGS

override CFLAGS += $(EXTRA_WARNINGS)

override CFLAGS += -Werror -Wall

override CFLAGS += -fPIC

override CFLAGS += $(INCLUDES)



ifeq ($(VERBOSE),1)

  Q =

else

  Q = @

endif



# Disable command line variables (CFLAGS) overide from top

# level Makefile (perf), otherwise build Makefile will get

# the same command line setup.

MAKEOVERRIDES=



export srctree OUTPUT CC LD CFLAGS V

build := -f $(srctree)/tools/build/Makefile.build dir=. obj



BPF_IN    := $(OUTPUT)libbpf-in.o

LIB_FILE := $(addprefix $(OUTPUT),$(LIB_FILE))



CMD_TARGETS = $(LIB_FILE)



TARGETS = $(CMD_TARGETS)



all: $(VERSION_FILES) all_cmd



all_cmd: $(CMD_TARGETS)



$(BPF_IN): force elfdep bpfdep

	$(Q)$(MAKE) $(build)=libbpf



$(OUTPUT)libbpf.so: $(BPF_IN)

	$(QUIET_LINK)$(CC) --shared $^ -o $@



$(OUTPUT)libbpf.a: $(BPF_IN)

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



define update_dir

  (echo $1 > $@.tmp;				\

   if [ -r $@ ] && cmp -s $@ $@.tmp; then	\

     rm -f $@.tmp;				\

   else						\

     echo '  UPDATE                 $@';	\

     mv -f $@.tmp $@;				\

   fi);

endef



define do_install

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

		$(INSTALL) -d -m 755 '$(DESTDIR_SQ)$2';	\

	fi;						\

	$(INSTALL) $1 '$(DESTDIR_SQ)$2'

endef



install_lib: all_cmd

	$(call QUIET_INSTALL, $(LIB_FILE)) \

		$(call do_install,$(LIB_FILE),$(libdir_SQ))



install: install_lib



### Cleaning rules



config-clean:

	$(call QUIET_CLEAN, config)

	$(Q)$(MAKE) -C $(srctree)/tools/build/feature/ clean >/dev/null



clean:

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

		$(RM) LIBBPF-CFLAGS

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







PHONY += force elfdep bpfdep

force:



elfdep:

	@if [ "$(feature-libelf)" != "1" ]; then echo "No libelf found"; exit -1 ; fi



bpfdep:

	@if [ "$(feature-bpf)" != "1" ]; then echo "BPF API too old"; exit -1 ; fi



# Declare the contents of the .PHONY variable as phony.  We keep that

# information in a variable so we can use it in if_changed and friends.

.PHONY: $(PHONY)