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>
---
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
