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.
Reported-by: Lorenz Bauer <lmb@xxxxxxxxxxxxxx>
Signed-off-by: Quentin Monnet <quentin.monnet@xxxxxxxxxxxxx>
---
tools/bpf/bpftool/Makefile | 12 +-
tools/testing/selftests/bpf/Makefile | 3 +-
.../selftests/bpf/test_bpftool_build.sh | 137 ++++++++++++++++++
3 files changed, 146 insertions(+), 6 deletions(-)
create mode 100755 tools/testing/selftests/bpf/test_bpftool_build.sh
diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile
index cd0fc05464e7..3fc82ff9b52c 100644
--- a/tools/bpf/bpftool/Makefile
+++ b/tools/bpf/bpftool/Makefile
@@ -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
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 1faad0c3c3c9..c7595b4ed55d 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -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 \
diff --git a/tools/testing/selftests/bpf/test_bpftool_build.sh b/tools/testing/selftests/bpf/test_bpftool_build.sh
new file mode 100755
index 000000000000..15dbea809a38
--- /dev/null
+++ b/tools/testing/selftests/bpf/test_bpftool_build.sh
@@ -0,0 +1,137 @@
+#!/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 [ $# -ge 1 ] ; then
+ check ${@: -1}
+ else
+ check .
+ fi
+ (
+ if [ $# -eq 1 ] ; then
+ cd ${@: -1}/bpftool
+ fi
+ make -s clean
+ )
+ echo
+}
+
+make_with_tmpdir() {
+ local ARGS
+
+ TMPDIR=$(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
+ 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
--
2.17.1
