Commit ec8d3b5c authored by Viktor Malik's avatar Viktor Malik Committed by Andrii Nakryiko
Browse files

selftests/bpf: Allow building with extra flags 



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 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: default avatarViktor Malik <vmalik@redhat.com>
Reviewed-by: default avatarToke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
parent 5f67329c

tools/testing/selftests/bpf/Makefile

+23 −11
Original line number Diff line number Diff line
@@ -297,25 +297,33 @@ $(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 $@



$(OUTPUT)/bpf_test_modorder_x.ko: $(VMLINUX_BTF) $(RESOLVE_BTFIDS) $(wildcard bpf_test_modorder_x/Makefile bpf_test_modorder_x/*.[ch])

	$(call msg,MOD,,$@)

	$(Q)$(RM) bpf_test_modorder_x/bpf_test_modorder_x.ko # force re-compilation

	$(Q)$(MAKE) $(submake_extras) RESOLVE_BTFIDS=$(RESOLVE_BTFIDS) -C bpf_test_modorder_x

	$(Q)$(MAKE) $(submake_extras) -C bpf_test_modorder_x \

		RESOLVE_BTFIDS=$(RESOLVE_BTFIDS)	     \

		EXTRA_CFLAGS='' EXTRA_LDFLAGS=''

	$(Q)cp bpf_test_modorder_x/bpf_test_modorder_x.ko $@



$(OUTPUT)/bpf_test_modorder_y.ko: $(VMLINUX_BTF) $(RESOLVE_BTFIDS) $(wildcard bpf_test_modorder_y/Makefile bpf_test_modorder_y/*.[ch])

	$(call msg,MOD,,$@)

	$(Q)$(RM) bpf_test_modorder_y/bpf_test_modorder_y.ko # force re-compilation

	$(Q)$(MAKE) $(submake_extras) RESOLVE_BTFIDS=$(RESOLVE_BTFIDS) -C bpf_test_modorder_y

	$(Q)$(MAKE) $(submake_extras) -C bpf_test_modorder_y \

		RESOLVE_BTFIDS=$(RESOLVE_BTFIDS)	     \

		EXTRA_CFLAGS='' EXTRA_LDFLAGS=''

	$(Q)cp bpf_test_modorder_y/bpf_test_modorder_y.ko $@
@@ -335,8 +343,8 @@ $(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)
@@ -369,7 +377,8 @@ $(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)/			       \
@@ -380,7 +389,8 @@ $(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)/				\
@@ -403,8 +413,8 @@ $(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))
@@ -412,7 +422,9 @@ $(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