selftests: adopt BPF's approach to quieter builds

selftest build is fairly noisy, it's easy to miss warnings.
It's standard practice to add alternative messages in
the Makefile. I was grepping for existing solutions,
and found that bpf already has the right knobs.

Move them to lib.mk and adopt in net.
Convert the basic rules in lib.mk.
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20240411190534.444918-1-kuba@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/bpf/Makefile

@@ -135,18 +135,7 @@ TEST_GEN_PROGS_EXTENDED = test_sock_addr test_skb_cgroup_id_user \
 
 TEST_GEN_FILES += liburandom_read.so urandom_read sign-file uprobe_multi
 
-# Emit succinct information message describing current building step
-# $1 - generic step name (e.g., CC, LINK, etc);
-# $2 - optional "flavor" specifier; if provided, will be emitted as [flavor];
-# $3 - target (assumed to be file); only file name will be emitted;
-# $4 - optional extra arg, emitted as-is, if provided.
-ifeq ($(V),1)
-Q =
-msg =
-else
-Q = @
-msg = @printf '  %-8s%s %s%s\n' "$(1)" "$(if $(2), [$(2)])" "$(notdir $(3))" "$(if $(4), $(4))";
-MAKEFLAGS += --no-print-directory
+ifneq ($(V),1)
 submake_extras := feature_display=0
 endif
 

tools/testing/selftests/lib.mk

@@ -44,6 +44,20 @@ endif
 selfdir = $(realpath $(dir $(filter %/lib.mk,$(MAKEFILE_LIST))))
 top_srcdir = $(selfdir)/../../..
 
+# msg: emit succinct information message describing current building step
+# $1 - generic step name (e.g., CC, LINK, etc);
+# $2 - optional "flavor" specifier; if provided, will be emitted as [flavor];
+# $3 - target (assumed to be file); only file name will be emitted;
+# $4 - optional extra arg, emitted as-is, if provided.
+ifeq ($(V),1)
+Q =
+msg =
+else
+Q = @
+msg = @printf '  %-8s%s %s%s\n' "$(1)" "$(if $(2), [$(2)])" "$(notdir $(3))" "$(if $(4), $(4))";
+MAKEFLAGS += --no-print-directory
+endif
+
 ifeq ($(KHDR_INCLUDES),)
 KHDR_INCLUDES := -isystem $(top_srcdir)/usr/include
 endif
@@ -176,7 +190,8 @@ endif
 ifeq ($(OVERRIDE_TARGETS),)
 LOCAL_HDRS += $(selfdir)/kselftest_harness.h $(selfdir)/kselftest.h
 $(OUTPUT)/%:%.c $(LOCAL_HDRS)
-	$(LINK.c) $(filter-out $(LOCAL_HDRS),$^) $(LDLIBS) -o $@
+	$(call msg,CC,,$@)
+	$(Q)$(LINK.c) $(filter-out $(LOCAL_HDRS),$^) $(LDLIBS) -o $@
 
 $(OUTPUT)/%.o:%.S
 	$(COMPILE.S) $^ -o $@

tools/testing/selftests/net/Makefile

@@ -125,7 +125,8 @@ BPFOBJ := $(BUILD_DIR)/libbpf/libbpf.a
 
 MAKE_DIRS := $(BUILD_DIR)/libbpf
 $(MAKE_DIRS):
-	mkdir -p $@
+	$(call msg,MKDIR,,$@)
+	$(Q)mkdir -p $@
 
 # Get Clang's default includes on this system, as opposed to those seen by
 # '--target=bpf'. This fixes "missing" files on some architectures/distros,
@@ -149,13 +150,15 @@ BPF_PROG_OBJS := $(OUTPUT)/nat6to4.o $(OUTPUT)/xdp_dummy.o \
 	$(OUTPUT)/sample_map_ret0.bpf.o $(OUTPUT)/sample_ret0.bpf.o
 
 $(BPF_PROG_OBJS): $(OUTPUT)/%.o : %.c $(BPFOBJ) | $(MAKE_DIRS)
-	$(CLANG) -O2 -g --target=bpf $(CCINCLUDE) $(CLANG_SYS_INCLUDES) \
+	$(call msg,BPF_PROG,,$@)
+	$(Q)$(CLANG) -O2 -g --target=bpf $(CCINCLUDE) $(CLANG_SYS_INCLUDES) \
 	-c $< -o $@
 
 $(BPFOBJ): $(wildcard $(BPFDIR)/*.[ch] $(BPFDIR)/Makefile)		       \
 	   $(APIDIR)/linux/bpf.h					       \
 	   | $(BUILD_DIR)/libbpf
-	$(MAKE) $(submake_extras) -C $(BPFDIR) OUTPUT=$(BUILD_DIR)/libbpf/     \
+	$(call msg,MAKE,,$@)
+	$(Q)$(MAKE) $(submake_extras) -C $(BPFDIR) OUTPUT=$(BUILD_DIR)/libbpf/ \
 		    EXTRA_CFLAGS='-g -O0'				       \
 		    DESTDIR=$(SCRATCH_DIR) prefix= all install_headers