selftests/bpf: Consolidate kernel modules into common directory

The selftests build four kernel modules which use copy-pasted Makefile
targets. This is a bit messy, and doesn't scale so well when we add more
modules, so let's consolidate these rules into a single rule generated
for each module name, and move the module sources into a single
directory.

To avoid parallel builds of the different modules stepping on each
other's toes during the 'modpost' phase of the Kbuild 'make modules',
the module files should really be a grouped target. However, make only
added explicit support for grouped targets in version 4.3, which is
newer than the minimum version supported by the kernel. However, make
implicitly treats pattern matching rules with multiple targets as a
grouped target, so we can work around this by turning the rule into a
pattern matching target. We do this by replacing '.ko' with '%ko' in the
targets with subst().

Signed-off-by: Toke Høiland-Jørgensen <[email protected]>
Signed-off-by: Andrii Nakryiko <[email protected]>
Acked-by: Viktor Malik <[email protected]>
Link: https://lore.kernel.org/bpf/[email protected]

Author: tohojo

tools/testing/selftests/bpf/Makefile

@@ -150,13 +150,13 @@ TEST_PROGS_EXTENDED := with_addr.sh \
 	with_tunnels.sh ima_setup.sh verify_sig_setup.sh \
 	test_xdp_vlan.sh test_bpftool.py
 
+TEST_KMODS := bpf_testmod.ko bpf_test_no_cfi.ko bpf_test_modorder_x.ko \
+	bpf_test_modorder_y.ko
+TEST_KMOD_TARGETS = $(addprefix $(OUTPUT)/,$(TEST_KMODS))
+
 # Compile but not part of 'make run_tests'
 TEST_GEN_PROGS_EXTENDED = \
 	bench \
-	bpf_testmod.ko \
-	bpf_test_modorder_x.ko \
-	bpf_test_modorder_y.ko \
-	bpf_test_no_cfi.ko \
 	flow_dissector_load \
 	runqslower \
 	test_cpp \
@@ -182,8 +182,9 @@ override define CLEAN
 	$(Q)$(RM) -r $(TEST_GEN_PROGS)
 	$(Q)$(RM) -r $(TEST_GEN_PROGS_EXTENDED)
 	$(Q)$(RM) -r $(TEST_GEN_FILES)
+	$(Q)$(RM) -r $(TEST_KMODS)
 	$(Q)$(RM) -r $(EXTRA_CLEAN)
-	$(Q)$(MAKE) -C bpf_testmod clean
+	$(Q)$(MAKE) -C test_kmods clean
 	$(Q)$(MAKE) docs-clean
 endef
 
@@ -249,7 +250,7 @@ endif
 # to build individual tests.
 # NOTE: Semicolon at the end is critical to override lib.mk's default static
 # rule for binaries.
-$(notdir $(TEST_GEN_PROGS)						\
+$(notdir $(TEST_GEN_PROGS) $(TEST_KMODS)				\
 	 $(TEST_GEN_PROGS_EXTENDED)): %: $(OUTPUT)/% ;
 
 # sort removes libbpf duplicates when not cross-building
@@ -303,37 +304,19 @@ $(OUTPUT)/sign-file: ../../../../scripts/sign-file.c
 		  $< -o $@ \
 		  $(shell $(PKG_CONFIG) --libs libcrypto 2> /dev/null || echo -lcrypto)
 
-$(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) $(submake_extras) -C bpf_testmod \
-		RESOLVE_BTFIDS=$(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) $(submake_extras) -C bpf_test_no_cfi \
-		RESOLVE_BTFIDS=$(RESOLVE_BTFIDS)	 \
+# This should really be a grouped target, but make versions before 4.3 don't
+# support that for regular rules. However, pattern matching rules are implicitly
+# treated as grouped even with older versions of make, so as a workaround, the
+# subst() turns the rule into a pattern matching rule
+$(addprefix test_kmods/,$(subst .ko,%ko,$(TEST_KMODS))): $(VMLINUX_BTF) $(RESOLVE_BTFIDS) $(wildcard test_kmods/Makefile test_kmods/*.[ch])
+	$(Q)$(RM) test_kmods/*.ko test_kmods/*.mod.o # force re-compilation
+	$(Q)$(MAKE) $(submake_extras) -C test_kmods	\
+		RESOLVE_BTFIDS=$(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) $(wildcard bpf_test_modorder_x/Makefile bpf_test_modorder_x/*.[ch])
+$(TEST_KMOD_TARGETS): $(addprefix test_kmods/,$(TEST_KMODS))
 	$(call msg,MOD,,$@)
-	$(Q)$(RM) bpf_test_modorder_x/bpf_test_modorder_x.ko # force re-compilation
-	$(Q)$(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) $(submake_extras) -C bpf_test_modorder_y \
-		RESOLVE_BTFIDS=$(RESOLVE_BTFIDS)	     \
-		EXTRA_CFLAGS='' EXTRA_LDFLAGS=''
-	$(Q)cp bpf_test_modorder_y/bpf_test_modorder_y.ko $@
+	$(Q)cp test_kmods/$(@F) $@
 
 
 DEFAULT_BPFTOOL := $(HOST_SCRATCH_DIR)/sbin/bpftool
@@ -758,14 +741,12 @@ TRUNNER_EXTRA_SOURCES := test_progs.c		\
 			 json_writer.c 		\
 			 flow_dissector_load.h	\
 			 ip_check_defrag_frags.h
-TRUNNER_EXTRA_FILES := $(OUTPUT)/urandom_read $(OUTPUT)/bpf_testmod.ko	\
-		       $(OUTPUT)/bpf_test_no_cfi.ko			\
-		       $(OUTPUT)/bpf_test_modorder_x.ko		\
-		       $(OUTPUT)/bpf_test_modorder_y.ko		\
+TRUNNER_EXTRA_FILES := $(OUTPUT)/urandom_read				\
 		       $(OUTPUT)/liburandom_read.so			\
 		       $(OUTPUT)/xdp_synproxy				\
 		       $(OUTPUT)/sign-file				\
 		       $(OUTPUT)/uprobe_multi				\
+		       $(TEST_KMOD_TARGETS)				\
 		       ima_setup.sh 					\
 		       verify_sig_setup.sh				\
 		       $(wildcard progs/btf_dump_test_case_*.c)		\
@@ -892,12 +873,9 @@ $(OUTPUT)/uprobe_multi: uprobe_multi.c uprobe_multi.ld
 
 EXTRA_CLEAN := $(SCRATCH_DIR) $(HOST_SCRATCH_DIR)			\
 	prog_tests/tests.h map_tests/tests.h verifier/tests.h		\
-	feature bpftool 						\
+	feature bpftool $(TEST_KMOD_TARGETS)				\
 	$(addprefix $(OUTPUT)/,*.o *.d *.skel.h *.lskel.h *.subskel.h	\
-			       no_alu32 cpuv4 bpf_gcc bpf_testmod.ko	\
-			       bpf_test_no_cfi.ko			\
-			       bpf_test_modorder_x.ko			\
-			       bpf_test_modorder_y.ko			\
+			       no_alu32 cpuv4 bpf_gcc			\
 			       liburandom_read.so)			\
 	$(OUTPUT)/FEATURE-DUMP.selftests
 

tools/testing/selftests/bpf/bpf_test_modorder_x/Makefile

@@ -2,7 +2,7 @@
 #define _GNU_SOURCE
 #include <test_progs.h>
 #include "progs/core_reloc_types.h"
-#include "bpf_testmod/bpf_testmod.h"
+#include "test_kmods/bpf_testmod.h"
 #include <linux/limits.h>
 #include <sys/mman.h>
 #include <sys/syscall.h>

tools/testing/selftests/bpf/bpf_test_modorder_y/Makefile

@@ -3,7 +3,7 @@
 #include <vmlinux.h>
 #include <bpf/bpf_helpers.h>
 #include <bpf/bpf_tracing.h>
-#include "../bpf_testmod/bpf_testmod.h"
+#include "../test_kmods/bpf_testmod.h"
 
 char _license[] SEC("license") = "GPL";
 

tools/testing/selftests/bpf/bpf_test_no_cfi/Makefile

@@ -2,7 +2,7 @@
 #include <vmlinux.h>
 #include <bpf/bpf_tracing.h>
 #include <bpf/bpf_helpers.h>
-#include "../bpf_testmod/bpf_testmod_kfunc.h"
+#include "../test_kmods/bpf_testmod_kfunc.h"
 
 struct map_value {
 	struct prog_test_ref_kfunc __kptr *ptr;

tools/testing/selftests/bpf/bpf_testmod/Makefile

@@ -4,8 +4,8 @@
 #include <vmlinux.h>
 #include <bpf/bpf_tracing.h>
 #include "bpf_misc.h"
-#include "../bpf_testmod/bpf_testmod.h"
-#include "../bpf_testmod/bpf_testmod_kfunc.h"
+#include "../test_kmods/bpf_testmod.h"
+#include "../test_kmods/bpf_testmod_kfunc.h"
 
 char _license[] SEC("license") = "GPL";
 

tools/testing/selftests/bpf/prog_tests/core_reloc.c

@@ -4,8 +4,8 @@
 #include <vmlinux.h>
 #include <bpf/bpf_tracing.h>
 #include "bpf_misc.h"
-#include "../bpf_testmod/bpf_testmod.h"
-#include "../bpf_testmod/bpf_testmod_kfunc.h"
+#include "../test_kmods/bpf_testmod.h"
+#include "../test_kmods/bpf_testmod_kfunc.h"
 
 char _license[] SEC("license") = "GPL";