selftests/bpf: Minor cleanups and normalization of Makefile

Few clean ups and single-line simplifications. Also split CLEAN command
into multiple $(RM) invocations as it gets dangerously close to too long
argument list. Make sure that -o <output.o> is used always as the last
argument for saner verbose make output.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211111053624.190580-3-andrii@kernel.org

tools/testing/selftests/bpf/Makefile

@@ -45,10 +45,8 @@ ifneq ($(BPF_GCC),)
 TEST_GEN_PROGS += test_progs-bpf_gcc
 endif
 
-TEST_GEN_FILES = test_lwt_ip_encap.o \
-	test_tc_edt.o
-TEST_FILES = xsk_prereqs.sh \
-	$(wildcard progs/btf_dump_test_case_*.c)
+TEST_GEN_FILES = test_lwt_ip_encap.o test_tc_edt.o
+TEST_FILES = xsk_prereqs.sh $(wildcard progs/btf_dump_test_case_*.c)
 
 # Order correspond to 'make run_tests' order
 TEST_PROGS := test_kmod.sh \
@@ -107,7 +105,10 @@ endif
 OVERRIDE_TARGETS := 1
 override define CLEAN
 	$(call msg,CLEAN)
-	$(Q)$(RM) -r $(TEST_GEN_PROGS) $(TEST_GEN_PROGS_EXTENDED) $(TEST_GEN_FILES) $(EXTRA_CLEAN)
+	$(Q)$(RM) -r $(TEST_GEN_PROGS)
+	$(Q)$(RM) -r $(TEST_GEN_PROGS_EXTENDED)
+	$(Q)$(RM) -r $(TEST_GEN_FILES)
+	$(Q)$(RM) -r $(EXTRA_CLEAN)
 	$(Q)$(MAKE) -C bpf_testmod clean
 	$(Q)$(MAKE) docs-clean
 endef
@@ -169,7 +170,7 @@ $(OUTPUT)/%:%.c
 
 $(OUTPUT)/urandom_read: urandom_read.c
 	$(call msg,BINARY,,$@)
-	$(Q)$(CC) $(LDFLAGS) -o $@ $< $(LDLIBS) -Wl,--build-id=sha1
+	$(Q)$(CC) $(LDFLAGS) $< $(LDLIBS) -Wl,--build-id=sha1 -o $@
 
 $(OUTPUT)/bpf_testmod.ko: $(VMLINUX_BTF) $(wildcard bpf_testmod/Makefile bpf_testmod/*.[ch])
 	$(call msg,MOD,,$@)
@@ -232,16 +233,16 @@ docs-clean:
 	            prefix= OUTPUT=$(OUTPUT)/ DESTDIR=$(OUTPUT)/ $@
 
 $(BPFOBJ): $(wildcard $(BPFDIR)/*.[ch] $(BPFDIR)/Makefile)		       \
-	   ../../../include/uapi/linux/bpf.h                                   \
+	   $(APIDIR)/linux/bpf.h					       \
 	   | $(BUILD_DIR)/libbpf
 	$(Q)$(MAKE) $(submake_extras) -C $(BPFDIR) OUTPUT=$(BUILD_DIR)/libbpf/ \
 		    EXTRA_CFLAGS='-g -O0'				       \
 		    DESTDIR=$(SCRATCH_DIR) prefix= all install_headers
 
 ifneq ($(BPFOBJ),$(HOST_BPFOBJ))
-$(HOST_BPFOBJ): $(wildcard $(BPFDIR)/*.[ch] $(BPFDIR)/Makefile)                \
-	   ../../../include/uapi/linux/bpf.h                                   \
-	   | $(HOST_BUILD_DIR)/libbpf
+$(HOST_BPFOBJ): $(wildcard $(BPFDIR)/*.[ch] $(BPFDIR)/Makefile)		       \
+		$(APIDIR)/linux/bpf.h					       \
+		| $(HOST_BUILD_DIR)/libbpf
 	$(Q)$(MAKE) $(submake_extras) -C $(BPFDIR)                             \
 		    EXTRA_CFLAGS='-g -O0'				       \
 		    OUTPUT=$(HOST_BUILD_DIR)/libbpf/ CC=$(HOSTCC) LD=$(HOSTLD) \
@@ -305,12 +306,12 @@ $(OUTPUT)/flow_dissector_load.o: flow_dissector_load.h
 # $3 - CFLAGS
 define CLANG_BPF_BUILD_RULE
 	$(call msg,CLNG-BPF,$(TRUNNER_BINARY),$2)
-	$(Q)$(CLANG) $3 -O2 -target bpf -c $1 -o $2 -mcpu=v3
+	$(Q)$(CLANG) $3 -O2 -target bpf -c $1 -mcpu=v3 -o $2
 endef
 # Similar to CLANG_BPF_BUILD_RULE, but with disabled alu32
 define CLANG_NOALU32_BPF_BUILD_RULE
 	$(call msg,CLNG-BPF,$(TRUNNER_BINARY),$2)
-	$(Q)$(CLANG) $3 -O2 -target bpf -c $1 -o $2 -mcpu=v2
+	$(Q)$(CLANG) $3 -O2 -target bpf -c $1 -mcpu=v2 -o $2
 endef
 # Build BPF object using GCC
 define GCC_BPF_BUILD_RULE
@@ -472,13 +473,12 @@ TRUNNER_TESTS_DIR := prog_tests
 TRUNNER_BPF_PROGS_DIR := progs
 TRUNNER_EXTRA_SOURCES := test_progs.c cgroup_helpers.c trace_helpers.c	\
 			 network_helpers.c testing_helpers.c		\
-			 btf_helpers.c	flow_dissector_load.h
+			 btf_helpers.c flow_dissector_load.h
 TRUNNER_EXTRA_FILES := $(OUTPUT)/urandom_read $(OUTPUT)/bpf_testmod.ko	\
 		       ima_setup.sh					\
 		       $(wildcard progs/btf_dump_test_case_*.c)
 TRUNNER_BPF_BUILD_RULE := CLANG_BPF_BUILD_RULE
-TRUNNER_BPF_CFLAGS := $(BPF_CFLAGS) $(CLANG_CFLAGS)
-TRUNNER_BPF_CFLAGS += -DENABLE_ATOMICS_TESTS
+TRUNNER_BPF_CFLAGS := $(BPF_CFLAGS) $(CLANG_CFLAGS) -DENABLE_ATOMICS_TESTS
 $(eval $(call DEFINE_TEST_RUNNER,test_progs))
 
 # Define test_progs-no_alu32 test runner.
@@ -540,7 +540,7 @@ $(OUTPUT)/bench: $(OUTPUT)/bench.o $(OUTPUT)/testing_helpers.o \
 		 $(OUTPUT)/bench_ringbufs.o \
 		 $(OUTPUT)/bench_bloom_filter_map.o
 	$(call msg,BINARY,,$@)
-	$(Q)$(CC) $(LDFLAGS) -o $@ $(filter %.a %.o,$^) $(LDLIBS)
+	$(Q)$(CC) $(LDFLAGS) $(filter %.a %.o,$^) $(LDLIBS) -o $@
 
 EXTRA_CLEAN := $(TEST_CUSTOM_PROGS) $(SCRATCH_DIR) $(HOST_SCRATCH_DIR)	\
 	prog_tests/tests.h map_tests/tests.h verifier/tests.h		\