s390/expoline: Make modules use kernel expolines

Currently, kernel modules contain their own set of expoline thunks. In
the case of EXPOLINE_EXTERN, this involves postlinking of precompiled
expoline.o. expoline.o is also necessary for out-of-source tree module
builds.

Now that the kernel modules area is less than 4 GB away from
kernel expoline thunks, make modules use kernel expolines. Also make
EXPOLINE_EXTERN the default if the compiler supports it. This simplifies
build and aligns with the approach adopted by other architectures.

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/arch/s390/include/asm/nospec-branch.h b/arch/s390/include/asm/nospec-branch.h
index 82725cf783c7..b9c1f3cae842 100644
--- a/arch/s390/include/asm/nospec-branch.h
+++ b/arch/s390/include/asm/nospec-branch.h
@@ -17,6 +17,26 @@ static inline bool nospec_uses_trampoline(void)
 	return __is_defined(CC_USING_EXPOLINE) && !nospec_disable;
 }
 
+#ifdef CONFIG_EXPOLINE_EXTERN
+
+void __s390_indirect_jump_r1(void);
+void __s390_indirect_jump_r2(void);
+void __s390_indirect_jump_r3(void);
+void __s390_indirect_jump_r4(void);
+void __s390_indirect_jump_r5(void);
+void __s390_indirect_jump_r6(void);
+void __s390_indirect_jump_r7(void);
+void __s390_indirect_jump_r8(void);
+void __s390_indirect_jump_r9(void);
+void __s390_indirect_jump_r10(void);
+void __s390_indirect_jump_r11(void);
+void __s390_indirect_jump_r12(void);
+void __s390_indirect_jump_r13(void);
+void __s390_indirect_jump_r14(void);
+void __s390_indirect_jump_r15(void);
+
+#endif
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* _ASM_S390_EXPOLINE_H */