certs: refactor file cleaning

'make clean' removes files listed in 'targets'. It is redundant to
specify both 'targets' and 'clean-files'.

Move 'targets' assignments out of the ifeq-conditionals so
scripts/Makefile.clean can see them.

One effective change is that certs/certs/signing_key.x509 is now
deleted by 'make clean' instead of 'make mrproper. This certificate
is embedded in the kernel. It is not used in any way by external
module builds.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <n.schier@avm.de>

Author: masahir0y

Makefile

@@ -1494,7 +1494,7 @@ MRPROPER_FILES += include/config include/generated          \
 		  debian snap tar-install \
 		  .config .config.old .version \
 		  Module.symvers \
-		  certs/signing_key.pem certs/signing_key.x509 \
+		  certs/signing_key.pem \
 		  certs/x509.genkey \
 		  vmlinux-gdb.py \
 		  *.spec

certs/Makefile

@@ -22,12 +22,11 @@ $(eval $(call config_filename,SYSTEM_TRUSTED_KEYS))
 # GCC doesn't include .incbin files in -MD generated dependencies (PR#66871)
 $(obj)/system_certificates.o: $(obj)/x509_certificate_list
 
-targets += x509_certificate_list
 $(obj)/x509_certificate_list: scripts/extract-cert $(SYSTEM_TRUSTED_KEYS_SRCPREFIX)$(SYSTEM_TRUSTED_KEYS_FILENAME) FORCE
 	$(call if_changed,extract_certs,$(SYSTEM_TRUSTED_KEYS_SRCPREFIX)$(CONFIG_SYSTEM_TRUSTED_KEYS))
 endif # CONFIG_SYSTEM_TRUSTED_KEYRING
 
-clean-files := x509_certificate_list .x509.list x509_revocation_list
+targets += x509_certificate_list
 
 ifeq ($(CONFIG_MODULE_SIG),y)
 	SIGN_KEY = y
@@ -84,18 +83,20 @@ endif
 # GCC PR#66871 again.
 $(obj)/system_certificates.o: $(obj)/signing_key.x509
 
-targets += signing_key.x509
 $(obj)/signing_key.x509: scripts/extract-cert $(X509_DEP) FORCE
 	$(call if_changed,extract_certs,$(MODULE_SIG_KEY_SRCPREFIX)$(CONFIG_MODULE_SIG_KEY))
 endif # CONFIG_MODULE_SIG
 
+targets += signing_key.x509
+
 ifeq ($(CONFIG_SYSTEM_REVOCATION_LIST),y)
 
 $(eval $(call config_filename,SYSTEM_REVOCATION_KEYS))
 
 $(obj)/revocation_certificates.o: $(obj)/x509_revocation_list
 
-targets += x509_revocation_list
 $(obj)/x509_revocation_list: scripts/extract-cert $(SYSTEM_REVOCATION_KEYS_SRCPREFIX)$(SYSTEM_REVOCATION_KEYS_FILENAME) FORCE
 	$(call if_changed,extract_certs,$(SYSTEM_REVOCATION_KEYS_SRCPREFIX)$(CONFIG_SYSTEM_REVOCATION_KEYS))
 endif
+
+targets += x509_revocation_list