[PATCH 1/2] s390/nospec: build expoline.o for modules_prepare target

[Vasily Gorbik <gor@xxxxxxxxxxxxx>]

When CONFIG_EXPOLINE_EXTERN is used expoline thunks are generated
from arch/s390/lib/expoline.S and postlinked into every module.
This is also true for external modules. Add expoline.o build to
the modules_prepare target.

Fixes: 1d2ad084800e ("s390/nospec: add an option to use thunk-extern")
Reported-by: Joe Lawrence <joe.lawrence@xxxxxxxxxx>
Tested-by: Sumanth Korikkar <sumanthk@xxxxxxxxxxxxx>
Acked-by: Sumanth Korikkar <sumanthk@xxxxxxxxxxxxx>
Signed-off-by: Vasily Gorbik <gor@xxxxxxxxxxxxx>
---
 arch/s390/Makefile                      | 8 +++++++-
 arch/s390/lib/Makefile                  | 3 ++-
 arch/s390/lib/expoline/Makefile         | 3 +++
 arch/s390/lib/{ => expoline}/expoline.S | 0
 4 files changed, 12 insertions(+), 2 deletions(-)
 create mode 100644 arch/s390/lib/expoline/Makefile
 rename arch/s390/lib/{ => expoline}/expoline.S (100%)

diff --git a/arch/s390/Makefile b/arch/s390/Makefile
index 495c68a4df1e..fc72a35a1f07 100644
--- a/arch/s390/Makefile
+++ b/arch/s390/Makefile
@@ -82,7 +82,7 @@ endif
 
 ifdef CONFIG_EXPOLINE
   ifdef CONFIG_EXPOLINE_EXTERN
-    KBUILD_LDFLAGS_MODULE += arch/s390/lib/expoline.o
+    KBUILD_LDFLAGS_MODULE += arch/s390/lib/expoline/expoline.o
     CC_FLAGS_EXPOLINE := -mindirect-branch=thunk-extern
     CC_FLAGS_EXPOLINE += -mfunction-return=thunk-extern
   else
@@ -163,6 +163,12 @@ vdso_prepare: prepare0
 	$(Q)$(MAKE) $(build)=arch/s390/kernel/vdso64 include/generated/vdso64-offsets.h
 	$(if $(CONFIG_COMPAT),$(Q)$(MAKE) \
 		$(build)=arch/s390/kernel/vdso32 include/generated/vdso32-offsets.h)
+
+ifdef CONFIG_EXPOLINE_EXTERN
+modules_prepare: expoline_prepare
+expoline_prepare: prepare0
+	$(Q)$(MAKE) $(build)=arch/s390/lib/expoline arch/s390/lib/expoline/expoline.o
+endif
 endif
 
 # Don't use tabs in echo arguments
diff --git a/arch/s390/lib/Makefile b/arch/s390/lib/Makefile
index 5d415b3db6d1..580d2e3265cb 100644
--- a/arch/s390/lib/Makefile
+++ b/arch/s390/lib/Makefile
@@ -7,7 +7,6 @@ lib-y += delay.o string.o uaccess.o find.o spinlock.o
 obj-y += mem.o xor.o
 lib-$(CONFIG_KPROBES) += probes.o
 lib-$(CONFIG_UPROBES) += probes.o
-obj-$(CONFIG_EXPOLINE_EXTERN) += expoline.o
 obj-$(CONFIG_S390_KPROBES_SANITY_TEST) += test_kprobes_s390.o
 test_kprobes_s390-objs += test_kprobes_asm.o test_kprobes.o
 
@@ -22,3 +21,5 @@ obj-$(CONFIG_S390_MODULES_SANITY_TEST) += test_modules.o
 obj-$(CONFIG_S390_MODULES_SANITY_TEST_HELPERS) += test_modules_helpers.o
 
 lib-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o
+
+obj-$(CONFIG_EXPOLINE_EXTERN) += expoline/
diff --git a/arch/s390/lib/expoline/Makefile b/arch/s390/lib/expoline/Makefile
new file mode 100644
index 000000000000..854631d9cb03
--- /dev/null
+++ b/arch/s390/lib/expoline/Makefile
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0
+
+obj-y += expoline.o
diff --git a/arch/s390/lib/expoline.S b/arch/s390/lib/expoline/expoline.S
similarity index 100%
rename from arch/s390/lib/expoline.S
rename to arch/s390/lib/expoline/expoline.S
-- 
2.35.1