[PATCH 2/3] randstruct: Force full rebuild when seed changes

[Kees Cook]

While the randstruct GCC plugin was being rebuilt if the randstruct
seed changed, Clangs build did not notice the change. Include the hash
header directly so that it becomes a universal build dependency and full
rebuilds will happen if it changes.

Signed-off-by: Kees Cook <kees@xxxxxxxxxx>
---
Cc: Masahiro Yamada <masahiroy@xxxxxxxxxx>
Cc: Nathan Chancellor <nathan@xxxxxxxxxx>
Cc: Nicolas Schier <nicolas.schier@xxxxxxxxx>
Cc: Petr Pavlu <petr.pavlu@xxxxxxxx>
Cc: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Cc: <linux-kbuild@xxxxxxxxxxxxxxx>
---
 include/linux/vermagic.h    |  1 -
 scripts/Makefile.randstruct |  3 ++-
 scripts/basic/Makefile      | 11 ++++++-----
 3 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/include/linux/vermagic.h b/include/linux/vermagic.h
index 939ceabcaf06..335c360d4f9b 100644
--- a/include/linux/vermagic.h
+++ b/include/linux/vermagic.h
@@ -33,7 +33,6 @@
 #define MODULE_VERMAGIC_MODVERSIONS ""
 #endif
 #ifdef RANDSTRUCT
-#include <generated/randstruct_hash.h>
 #define MODULE_RANDSTRUCT "RANDSTRUCT_" RANDSTRUCT_HASHED_SEED
 #else
 #define MODULE_RANDSTRUCT
diff --git a/scripts/Makefile.randstruct b/scripts/Makefile.randstruct
index 24e283e89893..ab87219c6149 100644
--- a/scripts/Makefile.randstruct
+++ b/scripts/Makefile.randstruct
@@ -12,6 +12,7 @@ randstruct-cflags-y	\
 	+= -frandomize-layout-seed-file=$(objtree)/scripts/basic/randstruct.seed
 endif
 
-export RANDSTRUCT_CFLAGS := $(randstruct-cflags-y)
+export RANDSTRUCT_CFLAGS := $(randstruct-cflags-y) \
+			    -include $(objtree)/scripts/basic/randstruct_hash.h
 
 KBUILD_CFLAGS	+= $(RANDSTRUCT_CFLAGS)
diff --git a/scripts/basic/Makefile b/scripts/basic/Makefile
index dd289a6725ac..31637ce4dc5c 100644
--- a/scripts/basic/Makefile
+++ b/scripts/basic/Makefile
@@ -8,9 +8,10 @@ hostprogs-always-y	+= fixdep
 # before running a Clang kernel build.
 gen-randstruct-seed	:= $(srctree)/scripts/gen-randstruct-seed.sh
 quiet_cmd_create_randstruct_seed = GENSEED $@
-cmd_create_randstruct_seed = \
-	$(CONFIG_SHELL) $(gen-randstruct-seed) \
-		$@ $(objtree)/include/generated/randstruct_hash.h
-$(obj)/randstruct.seed: $(gen-randstruct-seed) FORCE
+      cmd_create_randstruct_seed = $(CONFIG_SHELL) $(gen-randstruct-seed) \
+		$(obj)/randstruct.seed $(obj)/randstruct_hash.h
+
+$(obj)/randstruct_hash.h $(obj)/randstruct.seed: $(gen-randstruct-seed) FORCE
 	$(call if_changed,create_randstruct_seed)
-always-$(CONFIG_RANDSTRUCT) += randstruct.seed
+
+always-$(CONFIG_RANDSTRUCT) += randstruct.seed randstruct_hash.h
-- 
2.34.1