Commit 45c5589d authored by Quentin Monnet's avatar Quentin Monnet Committed by Daniel Borkmann
Browse files

tools: bpftool: improve and check builds for different make invocations 



There are a number of alternative "make" invocations that can be used to
compile bpftool. The following invocations are expected to work:

  - through the kbuild system, from the top of the repository
    (make tools/bpf)
  - by telling make to change to the bpftool directory
    (make -C tools/bpf/bpftool)
  - by building the BPF tools from tools/
    (cd tools && make bpf)
  - by running make from bpftool directory
    (cd tools/bpf/bpftool && make)

Additionally, setting the O or OUTPUT variables should tell the build
system to use a custom output path, for each of these alternatives.

The following patch fixes the following invocations:

  $ make tools/bpf
  $ make tools/bpf O=<dir>
  $ make -C tools/bpf/bpftool OUTPUT=<dir>
  $ make -C tools/bpf/bpftool O=<dir>
  $ cd tools/ && make bpf O=<dir>
  $ cd tools/bpf/bpftool && make OUTPUT=<dir>
  $ cd tools/bpf/bpftool && make O=<dir>

After this commit, the build still fails for two variants when passing
the OUTPUT variable:

  $ make tools/bpf OUTPUT=<dir>
  $ cd tools/ && make bpf OUTPUT=<dir>

In order to remember and check what make invocations are supposed to
work, and to document the ones which do not, a new script is added to
the BPF selftests. Note that some invocations require the kernel to be
configured, so the script skips them if no .config file is found.

v2:
- In make_and_clean(), set $ERROR to 1 when "make" returns non-zero,
  even if the binary was produced.
- Run "make clean" from the correct directory (bpf/ instead of bpftool/,
  when relevant).

Reported-by: default avatarLorenz Bauer <lmb@cloudflare.com>
Signed-off-by: default avatarQuentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: default avatarJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent e0a43aa3

tools/bpf/bpftool/Makefile

+7 −5
Original line number Diff line number Diff line
@@ -17,21 +17,23 @@ endif 
BPF_DIR = $(srctree)/tools/lib/bpf/



ifneq ($(OUTPUT),)

  BPF_PATH = $(OUTPUT)

  LIBBPF_OUTPUT = $(OUTPUT)/libbpf/

  LIBBPF_PATH = $(LIBBPF_OUTPUT)

else

  BPF_PATH = $(BPF_DIR)

  LIBBPF_PATH = $(BPF_DIR)

endif



LIBBPF = $(BPF_PATH)libbpf.a

LIBBPF = $(LIBBPF_PATH)libbpf.a



BPFTOOL_VERSION := $(shell make -rR --no-print-directory -sC ../../.. kernelversion)



$(LIBBPF): FORCE

	$(Q)$(MAKE) -C $(BPF_DIR) OUTPUT=$(OUTPUT) $(OUTPUT)libbpf.a

	$(if $(LIBBPF_OUTPUT),@mkdir -p $(LIBBPF_OUTPUT))

	$(Q)$(MAKE) -C $(BPF_DIR) OUTPUT=$(LIBBPF_OUTPUT) $(LIBBPF_OUTPUT)libbpf.a



$(LIBBPF)-clean:

	$(call QUIET_CLEAN, libbpf)

	$(Q)$(MAKE) -C $(BPF_DIR) OUTPUT=$(OUTPUT) clean >/dev/null

	$(Q)$(MAKE) -C $(BPF_DIR) OUTPUT=$(LIBBPF_OUTPUT) clean >/dev/null



prefix ?= /usr/local

bash_compdir ?= /usr/share/bash-completion/completions

tools/testing/selftests/bpf/Makefile

+2 −1
Original line number Diff line number Diff line
@@ -63,7 +63,8 @@ TEST_PROGS := test_kmod.sh \ 
	test_tcp_check_syncookie.sh \

	test_tc_tunnel.sh \

	test_tc_edt.sh \

	test_xdping.sh

	test_xdping.sh \

	test_bpftool_build.sh



TEST_PROGS_EXTENDED := with_addr.sh \

	with_tunnels.sh \

tools/testing/selftests/bpf/test_bpftool_build.sh

0 → 100755
+143 −0
Original line number Diff line number Diff line 
#!/bin/bash

# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)



ERROR=0

TMPDIR=



# If one build fails, continue but return non-0 on exit.

return_value() {

	if [ -d "$TMPDIR" ] ; then

		rm -rf -- $TMPDIR

	fi

	exit $ERROR

}

trap return_value EXIT



case $1 in

	-h|--help)

		echo -e "$0 [-j <n>]"

		echo -e "\tTest the different ways of building bpftool."

		echo -e ""

		echo -e "\tOptions:"

		echo -e "\t\t-j <n>:\tPass -j flag to 'make'."

		exit

		;;

esac



J=$*



# Assume script is located under tools/testing/selftests/bpf/. We want to start

# build attempts from the top of kernel repository.

SCRIPT_REL_PATH=$(realpath --relative-to=$PWD $0)

SCRIPT_REL_DIR=$(dirname $SCRIPT_REL_PATH)

KDIR_ROOT_DIR=$(realpath $PWD/$SCRIPT_REL_DIR/../../../../)

cd $KDIR_ROOT_DIR



check() {

	local dir=$(realpath $1)



	echo -n "binary:  "

	# Returns non-null if file is found (and "false" is run)

	find $dir -type f -executable -name bpftool -print -exec false {} + && \

		ERROR=1 && printf "FAILURE: Did not find bpftool\n"

}



make_and_clean() {

	echo -e "\$PWD:    $PWD"

	echo -e "command: make -s $* >/dev/null"

	make $J -s $* >/dev/null

	if [ $? -ne 0 ] ; then

		ERROR=1

	fi

	if [ $# -ge 1 ] ; then

		check ${@: -1}

	else

		check .

	fi

	(

		if [ $# -ge 1 ] ; then

			cd ${@: -1}

		fi

		make -s clean

	)

	echo

}



make_with_tmpdir() {

	local ARGS



	TMPDIR=$(mktemp -d)

	if [ $# -ge 2 ] ; then

		ARGS=${@:1:(($# - 1))}

	fi

	echo -e "\$PWD:    $PWD"

	echo -e "command: make -s $ARGS ${@: -1}=$TMPDIR/ >/dev/null"

	make $J -s $ARGS ${@: -1}=$TMPDIR/ >/dev/null

	if [ $? -ne 0 ] ; then

		ERROR=1

	fi

	check $TMPDIR

	rm -rf -- $TMPDIR

	echo

}



echo "Trying to build bpftool"

echo -e "... through kbuild\n"



if [ -f ".config" ] ; then

	make_and_clean tools/bpf



	## $OUTPUT is overwritten in kbuild Makefile, and thus cannot be passed

	## down from toplevel Makefile to bpftool's Makefile.



	# make_with_tmpdir tools/bpf OUTPUT

	echo -e "skip:    make tools/bpf OUTPUT=<dir> (not supported)\n"



	make_with_tmpdir tools/bpf O

else

	echo -e "skip:    make tools/bpf (no .config found)\n"

	echo -e "skip:    make tools/bpf OUTPUT=<dir> (not supported)\n"

	echo -e "skip:    make tools/bpf O=<dir> (no .config found)\n"

fi



echo -e "... from kernel source tree\n"



make_and_clean -C tools/bpf/bpftool



make_with_tmpdir -C tools/bpf/bpftool OUTPUT



make_with_tmpdir -C tools/bpf/bpftool O



echo -e "... from tools/\n"

cd tools/



make_and_clean bpf



## In tools/bpf/Makefile, function "descend" is called and passes $(O) and

## $(OUTPUT). We would like $(OUTPUT) to have "bpf/bpftool/" appended before

## calling bpftool's Makefile, but this is not the case as the "descend"

## function focuses on $(O)/$(subdir). However, in the present case, updating

## $(O) to have $(OUTPUT) recomputed from it in bpftool's Makefile does not

## work, because $(O) is not defined from command line and $(OUTPUT) is not

## updated in tools/scripts/Makefile.include.

##

## Workarounds would require to a) edit "descend" or use an alternative way to

## call bpftool's Makefile, b) modify the conditions to update $(OUTPUT) and

## other variables in tools/scripts/Makefile.include (at the risk of breaking

## the build of other tools), or c) append manually the "bpf/bpftool" suffix to

## $(OUTPUT) in bpf's Makefile, which may break if targets for other directories

## use "descend" in the future.



# make_with_tmpdir bpf OUTPUT

echo -e "skip:    make bpf OUTPUT=<dir> (not supported)\n"



make_with_tmpdir bpf O



echo -e "... from bpftool's dir\n"

cd bpf/bpftool



make_and_clean



make_with_tmpdir OUTPUT



make_with_tmpdir O

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