On Fri, Oct 18, 2024 at 08:48:59AM +0200, Viktor Malik wrote: > In order to specify extra compilation or linking flags to BPF selftests, > it is possible to set EXTRA_CFLAGS and EXTRA_LDFLAGS from the command > line. The problem is that they are not propagated to sub-make calls > (runqslower, bpftool, libbpf) and in the better case are not applied, in > the worse case cause the entire build fail. > > Propagate EXTRA_CFLAGS and EXTRA_LDFLAGS to the sub-makes. > > This, for instance, allows to build selftests as PIE with > > $ make EXTRA_CFLAGS='-fPIE' EXTRA_LDFLAGS='-pie' > > Without this change, the command would fail because libbpf.a would not > be built with -fPIE and other PIE binaries would not link against it. > > The only problem is that we have to explicitly provide empty > EXTRA_CFLAGS='' and EXTRA_LDFLAGS='' to the builds of kernel modules > (bpf_testmod and bpf_test_no_cfi) as we don't want to build modules with > flags used for userspace (the above example would fail as kernel doesn't > support PIE). > > Signed-off-by: Viktor Malik <vmalik@xxxxxxxxxx> > Tested-by: Eduard Zingerman <eddyz87@xxxxxxxxx> lgtm Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx> jirka > --- > tools/testing/selftests/bpf/Makefile | 26 +++++++++++++++++--------- > 1 file changed, 17 insertions(+), 9 deletions(-) > > diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile > index 28a76baa854d..1fc7c38e56b5 100644 > --- a/tools/testing/selftests/bpf/Makefile > +++ b/tools/testing/selftests/bpf/Makefile > @@ -294,13 +294,17 @@ $(OUTPUT)/sign-file: ../../../../scripts/sign-file.c > $(OUTPUT)/bpf_testmod.ko: $(VMLINUX_BTF) $(RESOLVE_BTFIDS) $(wildcard bpf_testmod/Makefile bpf_testmod/*.[ch]) > $(call msg,MOD,,$@) > $(Q)$(RM) bpf_testmod/bpf_testmod.ko # force re-compilation > - $(Q)$(MAKE) $(submake_extras) RESOLVE_BTFIDS=$(RESOLVE_BTFIDS) -C bpf_testmod > + $(Q)$(MAKE) $(submake_extras) -C bpf_testmod \ > + RESOLVE_BTFIDS=$(RESOLVE_BTFIDS) \ > + EXTRA_CFLAGS='' EXTRA_LDFLAGS='' > $(Q)cp bpf_testmod/bpf_testmod.ko $@ > > $(OUTPUT)/bpf_test_no_cfi.ko: $(VMLINUX_BTF) $(RESOLVE_BTFIDS) $(wildcard bpf_test_no_cfi/Makefile bpf_test_no_cfi/*.[ch]) > $(call msg,MOD,,$@) > $(Q)$(RM) bpf_test_no_cfi/bpf_test_no_cfi.ko # force re-compilation > - $(Q)$(MAKE) $(submake_extras) RESOLVE_BTFIDS=$(RESOLVE_BTFIDS) -C bpf_test_no_cfi > + $(Q)$(MAKE) $(submake_extras) -C bpf_test_no_cfi \ > + RESOLVE_BTFIDS=$(RESOLVE_BTFIDS) \ > + EXTRA_CFLAGS='' EXTRA_LDFLAGS='' > $(Q)cp bpf_test_no_cfi/bpf_test_no_cfi.ko $@ > > DEFAULT_BPFTOOL := $(HOST_SCRATCH_DIR)/sbin/bpftool > @@ -319,8 +323,8 @@ $(OUTPUT)/runqslower: $(BPFOBJ) | $(DEFAULT_BPFTOOL) $(RUNQSLOWER_OUTPUT) > BPFTOOL_OUTPUT=$(HOST_BUILD_DIR)/bpftool/ \ > BPFOBJ_OUTPUT=$(BUILD_DIR)/libbpf/ \ > BPFOBJ=$(BPFOBJ) BPF_INCLUDE=$(INCLUDE_DIR) \ > - EXTRA_CFLAGS='-g $(OPT_FLAGS) $(SAN_CFLAGS)' \ > - EXTRA_LDFLAGS='$(SAN_LDFLAGS)' && \ > + EXTRA_CFLAGS='-g $(OPT_FLAGS) $(SAN_CFLAGS) $(EXTRA_CFLAGS)' \ > + EXTRA_LDFLAGS='$(SAN_LDFLAGS) $(EXTRA_LDFLAGS)' && \ > cp $(RUNQSLOWER_OUTPUT)runqslower $@ > > TEST_GEN_PROGS_EXTENDED += $(TRUNNER_BPFTOOL) > @@ -354,7 +358,8 @@ $(DEFAULT_BPFTOOL): $(wildcard $(BPFTOOLDIR)/*.[ch] $(BPFTOOLDIR)/Makefile) \ > $(HOST_BPFOBJ) | $(HOST_BUILD_DIR)/bpftool > $(Q)$(MAKE) $(submake_extras) -C $(BPFTOOLDIR) \ > ARCH= CROSS_COMPILE= CC="$(HOSTCC)" LD="$(HOSTLD)" \ > - EXTRA_CFLAGS='-g $(OPT_FLAGS)' \ > + EXTRA_CFLAGS='-g $(OPT_FLAGS) $(EXTRA_CFLAGS)' \ > + EXTRA_LDFLAGS='$(EXTRA_LDFLAGS)' \ > OUTPUT=$(HOST_BUILD_DIR)/bpftool/ \ > LIBBPF_OUTPUT=$(HOST_BUILD_DIR)/libbpf/ \ > LIBBPF_DESTDIR=$(HOST_SCRATCH_DIR)/ \ > @@ -365,7 +370,8 @@ $(CROSS_BPFTOOL): $(wildcard $(BPFTOOLDIR)/*.[ch] $(BPFTOOLDIR)/Makefile) \ > $(BPFOBJ) | $(BUILD_DIR)/bpftool > $(Q)$(MAKE) $(submake_extras) -C $(BPFTOOLDIR) \ > ARCH=$(ARCH) CROSS_COMPILE=$(CROSS_COMPILE) \ > - EXTRA_CFLAGS='-g $(OPT_FLAGS)' \ > + EXTRA_CFLAGS='-g $(OPT_FLAGS) $(EXTRA_CFLAGS)' \ > + EXTRA_LDFLAGS='$(EXTRA_LDFLAGS)' \ > OUTPUT=$(BUILD_DIR)/bpftool/ \ > LIBBPF_OUTPUT=$(BUILD_DIR)/libbpf/ \ > LIBBPF_DESTDIR=$(SCRATCH_DIR)/ \ > @@ -388,8 +394,8 @@ $(BPFOBJ): $(wildcard $(BPFDIR)/*.[ch] $(BPFDIR)/Makefile) \ > $(APIDIR)/linux/bpf.h \ > | $(BUILD_DIR)/libbpf > $(Q)$(MAKE) $(submake_extras) -C $(BPFDIR) OUTPUT=$(BUILD_DIR)/libbpf/ \ > - EXTRA_CFLAGS='-g $(OPT_FLAGS) $(SAN_CFLAGS)' \ > - EXTRA_LDFLAGS='$(SAN_LDFLAGS)' \ > + EXTRA_CFLAGS='-g $(OPT_FLAGS) $(SAN_CFLAGS) $(EXTRA_CFLAGS)' \ > + EXTRA_LDFLAGS='$(SAN_LDFLAGS) $(EXTRA_LDFLAGS)' \ > DESTDIR=$(SCRATCH_DIR) prefix= all install_headers > > ifneq ($(BPFOBJ),$(HOST_BPFOBJ)) > @@ -397,7 +403,9 @@ $(HOST_BPFOBJ): $(wildcard $(BPFDIR)/*.[ch] $(BPFDIR)/Makefile) \ > $(APIDIR)/linux/bpf.h \ > | $(HOST_BUILD_DIR)/libbpf > $(Q)$(MAKE) $(submake_extras) -C $(BPFDIR) \ > - EXTRA_CFLAGS='-g $(OPT_FLAGS)' ARCH= CROSS_COMPILE= \ > + ARCH= CROSS_COMPILE= \ > + EXTRA_CFLAGS='-g $(OPT_FLAGS) $(EXTRA_CFLAGS)' \ > + EXTRA_LDFLAGS='$(EXTRA_LDFLAGS)' \ > OUTPUT=$(HOST_BUILD_DIR)/libbpf/ \ > CC="$(HOSTCC)" LD="$(HOSTLD)" \ > DESTDIR=$(HOST_SCRATCH_DIR)/ prefix= all install_headers > -- > 2.47.0 >
