certs: fix and refactor CONFIG_SYSTEM_BLACKLIST_HASH_LIST build

Commit addf4663 ("certs: Check that builtin blacklist hashes are
valid") was applied 8 months after the submission.

In the meantime, the base code had been removed by commit b8c96a6b
("certs: simplify $(srctree)/ handling and remove config_filename
macro").

Fix the Makefile.

Create a local copy of $(CONFIG_SYSTEM_BLACKLIST_HASH_LIST). It is
included from certs/blacklist_hashes.c and also works as a timestamp.

Send error messages from check-blacklist-hashes.awk to stderr instead
of stdout.

Fixes: addf4663 ("certs: Check that builtin blacklist hashes are valid")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Reviewed-by: Mickaël Salaün <mic@linux.microsoft.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

certs/.gitignore

 # SPDX-License-Identifier: GPL-2.0-only
-/blacklist_hashes_checked
+/blacklist_hash_list
 /extract-cert
 /x509_certificate_list
 /x509_revocation_list

certs/Makefile

@@ -7,22 +7,22 @@ obj-$(CONFIG_SYSTEM_TRUSTED_KEYRING) += system_keyring.o system_certificates.o c
 obj-$(CONFIG_SYSTEM_BLACKLIST_KEYRING) += blacklist.o common.o
 obj-$(CONFIG_SYSTEM_REVOCATION_LIST) += revocation_certificates.o
 ifneq ($(CONFIG_SYSTEM_BLACKLIST_HASH_LIST),)
-quiet_cmd_check_blacklist_hashes = CHECK   $(patsubst "%",%,$(2))
-      cmd_check_blacklist_hashes = $(AWK) -f $(srctree)/scripts/check-blacklist-hashes.awk $(2); touch $@
 
-$(eval $(call config_filename,SYSTEM_BLACKLIST_HASH_LIST))
+$(obj)/blacklist_hashes.o: $(obj)/blacklist_hash_list
+CFLAGS_blacklist_hashes.o := -I $(obj)
 
-$(obj)/blacklist_hashes.o: $(obj)/blacklist_hashes_checked
+quiet_cmd_check_and_copy_blacklist_hash_list = GEN     $@
+      cmd_check_and_copy_blacklist_hash_list = \
+	$(AWK) -f $(srctree)/scripts/check-blacklist-hashes.awk $(CONFIG_SYSTEM_BLACKLIST_HASH_LIST) >&2; \
+	cat $(CONFIG_SYSTEM_BLACKLIST_HASH_LIST) > $@
 
-CFLAGS_blacklist_hashes.o += -I$(srctree)
-
-targets += blacklist_hashes_checked
-$(obj)/blacklist_hashes_checked: $(SYSTEM_BLACKLIST_HASH_LIST_SRCPREFIX)$(SYSTEM_BLACKLIST_HASH_LIST_FILENAME) scripts/check-blacklist-hashes.awk FORCE
-	$(call if_changed,check_blacklist_hashes,$(SYSTEM_BLACKLIST_HASH_LIST_SRCPREFIX)$(CONFIG_SYSTEM_BLACKLIST_HASH_LIST))
+$(obj)/blacklist_hash_list: $(CONFIG_SYSTEM_BLACKLIST_HASH_LIST) FORCE
+	$(call if_changed,check_and_copy_blacklist_hash_list)
 obj-$(CONFIG_SYSTEM_BLACKLIST_KEYRING) += blacklist_hashes.o
 else
 obj-$(CONFIG_SYSTEM_BLACKLIST_KEYRING) += blacklist_nohashes.o
 endif
+targets += blacklist_hash_list
 
 quiet_cmd_extract_certs  = CERT    $@
       cmd_extract_certs  = $(obj)/extract-cert $(extract-cert-in) $@
@@ -33,7 +33,7 @@ $(obj)/system_certificates.o: $(obj)/x509_certificate_list
 $(obj)/x509_certificate_list: $(CONFIG_SYSTEM_TRUSTED_KEYS) $(obj)/extract-cert FORCE
 	$(call if_changed,extract_certs)
 
-targets += x509_certificate_list blacklist_hashes_checked
+targets += x509_certificate_list
 
 # If module signing is requested, say by allyesconfig, but a key has not been
 # supplied, then one will need to be generated to make sure the build does not

certs/blacklist_hashes.c

@@ -2,6 +2,6 @@
 #include "blacklist.h"
 
 const char __initconst *const blacklist_hashes[] = {
-#include CONFIG_SYSTEM_BLACKLIST_HASH_LIST
+#include "blacklist_hash_list"
 	, NULL
 };