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>

8 files changed, 30 insertions, 17 deletions

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index df6b371ed214..a077ded1b9e6 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -555,7 +555,7 @@ config EXPOLINE
 	  If unsure, say N.
 
 config EXPOLINE_EXTERN
-	def_bool n
+	def_bool y if EXPOLINE
 	depends on EXPOLINE
 	depends on CC_IS_GCC && GCC_VERSION >= 110200
 	depends on $(success,$(srctree)/arch/s390/tools/gcc-thunk-extern.sh $(CC))
diff --git a/arch/s390/Makefile b/arch/s390/Makefile
index 2dbb2d2f22f9..64821f54f1e0 100644
--- a/arch/s390/Makefile
+++ b/arch/s390/Makefile
@@ -88,7 +88,6 @@ endif
 
 ifdef CONFIG_EXPOLINE
   ifdef CONFIG_EXPOLINE_EXTERN
-    KBUILD_LDFLAGS_MODULE += arch/s390/lib/expoline/expoline.o
     CC_FLAGS_EXPOLINE := -mindirect-branch=thunk-extern
     CC_FLAGS_EXPOLINE += -mfunction-return=thunk-extern
   else
@@ -167,11 +166,6 @@ vdso_prepare: prepare0
 vdso-install-y			+= arch/s390/kernel/vdso64/vdso64.so.dbg
 vdso-install-$(CONFIG_COMPAT)	+= arch/s390/kernel/vdso32/vdso32.so.dbg
 
-ifdef CONFIG_EXPOLINE_EXTERN
-modules_prepare: expoline_prepare
-expoline_prepare: scripts
-	$(Q)$(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/include/asm/asm-prototypes.h b/arch/s390/include/asm/asm-prototypes.h
index 56096ae26f29..f662eb4b9246 100644
--- a/arch/s390/include/asm/asm-prototypes.h
+++ b/arch/s390/include/asm/asm-prototypes.h
@@ -4,6 +4,7 @@
 #include <linux/kvm_host.h>
 #include <linux/ftrace.h>
 #include <asm/fpu.h>
+#include <asm/nospec-branch.h>
 #include <asm-generic/asm-prototypes.h>
 
 __int128_t __ashlti3(__int128_t a, int b);
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 */
diff --git a/arch/s390/include/asm/nospec-insn.h b/arch/s390/include/asm/nospec-insn.h
index 7a946c42ad13..cb15dd25bf21 100644
--- a/arch/s390/include/asm/nospec-insn.h
+++ b/arch/s390/include/asm/nospec-insn.h
@@ -16,24 +16,25 @@
  */
 	.macro __THUNK_PROLOG_NAME name
 #ifdef CONFIG_EXPOLINE_EXTERN
-	.pushsection .text,"ax",@progbits
-	__ALIGN
+	SYM_CODE_START(\name)
 #else
 	.pushsection .text.\name,"axG",@progbits,\name,comdat
-#endif
 	.globl \name
 	.hidden \name
 	.type \name,@function
 \name:
 	CFI_STARTPROC
+#endif
 	.endm
 
 	.macro __THUNK_EPILOG_NAME name
-	CFI_ENDPROC
 #ifdef CONFIG_EXPOLINE_EXTERN
-	.size \name, .-\name
-#endif
+	SYM_CODE_END(\name)
+	EXPORT_SYMBOL(\name)
+#else
+	CFI_ENDPROC
 	.popsection
+#endif
 	.endm
 
 	.macro __THUNK_PROLOG_BR r1
diff --git a/arch/s390/lib/Makefile b/arch/s390/lib/Makefile
index 90eac15ea62a..f43f897d3fc0 100644
--- a/arch/s390/lib/Makefile
+++ b/arch/s390/lib/Makefile
@@ -23,4 +23,4 @@ obj-$(CONFIG_S390_MODULES_SANITY_TEST_HELPERS) += test_modules_helpers.o
 
 lib-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o
 
-obj-$(CONFIG_EXPOLINE_EXTERN) += expoline/
+obj-$(CONFIG_EXPOLINE_EXTERN) += expoline.o
diff --git a/arch/s390/lib/expoline/expoline.S b/arch/s390/lib/expoline.S
index 92ed8409a7a4..92ed8409a7a4 100644
--- a/arch/s390/lib/expoline/expoline.S
+++ b/arch/s390/lib/expoline.S
diff --git a/arch/s390/lib/expoline/Makefile b/arch/s390/lib/expoline/Makefile
deleted file mode 100644
index 854631d9cb03..000000000000
--- a/arch/s390/lib/expoline/Makefile
+++ /dev/null
@@ -1,3 +0,0 @@
-# SPDX-License-Identifier: GPL-2.0
-
-obj-y += expoline.o