x86/entry: Refactor SYSCALL_DEFINEx macros

Pull the common code out from the SYSCALL_DEFINEx macros into a new
__SYS_STUBx macro.  Also conditionalize the X64 version in preparation for
enabling syscall wrappers on 32-bit native kernels.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200313195144.164260-2-brgerst@gmail.com

arch/x86/include/asm/syscall_wrapper.h

@@ -21,6 +21,22 @@ struct pt_regs;
 	      ,,(unsigned int)regs->dx,,(unsigned int)regs->si		\
 	      ,,(unsigned int)regs->di,,(unsigned int)regs->bp)
 
+#define __SYS_STUBx(abi, name, ...)					\
+	asmlinkage long __##abi##_##name(const struct pt_regs *regs);	\
+	ALLOW_ERROR_INJECTION(__##abi##_##name, ERRNO);			\
+	asmlinkage long __##abi##_##name(const struct pt_regs *regs)	\
+	{								\
+		return __se_##name(__VA_ARGS__);			\
+	}
+
+#ifdef CONFIG_X86_64
+#define __X64_SYS_STUBx(x, name, ...)					\
+	__SYS_STUBx(x64, sys##name,					\
+		    SC_X86_64_REGS_TO_ARGS(x, __VA_ARGS__))
+#else /* CONFIG_X86_64 */
+#define __X64_SYS_STUBx(x, name, ...)
+#endif /* CONFIG_X86_64 */
+
 #ifdef CONFIG_IA32_EMULATION
 /*
  * For IA32 emulation, we need to handle "compat" syscalls *and* create
@@ -39,20 +55,12 @@ struct pt_regs;
 	}
 
 #define __IA32_COMPAT_SYS_STUBx(x, name, ...)				\
-	asmlinkage long __ia32_compat_sys##name(const struct pt_regs *regs);\
-	ALLOW_ERROR_INJECTION(__ia32_compat_sys##name, ERRNO);		\
-	asmlinkage long __ia32_compat_sys##name(const struct pt_regs *regs)\
-	{								\
-		return __se_compat_sys##name(SC_IA32_REGS_TO_ARGS(x,__VA_ARGS__));\
-	}
+	__SYS_STUBx(ia32, compat_sys##name,				\
+		    SC_IA32_REGS_TO_ARGS(x, __VA_ARGS__))
 
 #define __IA32_SYS_STUBx(x, name, ...)					\
-	asmlinkage long __ia32_sys##name(const struct pt_regs *regs);	\
-	ALLOW_ERROR_INJECTION(__ia32_sys##name, ERRNO);			\
-	asmlinkage long __ia32_sys##name(const struct pt_regs *regs)	\
-	{								\
-		return __se_sys##name(SC_IA32_REGS_TO_ARGS(x,__VA_ARGS__));\
-	}
+	__SYS_STUBx(ia32, sys##name,					\
+		    SC_IA32_REGS_TO_ARGS(x, __VA_ARGS__))
 
 /*
  * To keep the naming coherent, re-define SYSCALL_DEFINE0 to create an alias
@@ -82,7 +90,7 @@ struct pt_regs;
 
 #else /* CONFIG_IA32_EMULATION */
 #define __IA32_COMPAT_SYS_STUBx(x, name, ...)
-#define __IA32_SYS_STUBx(x, fullname, name, ...)
+#define __IA32_SYS_STUBx(x, name, ...)
 #endif /* CONFIG_IA32_EMULATION */
 
 
@@ -101,12 +109,8 @@ struct pt_regs;
 	}
 
 #define __X32_COMPAT_SYS_STUBx(x, name, ...)				\
-	asmlinkage long __x32_compat_sys##name(const struct pt_regs *regs);\
-	ALLOW_ERROR_INJECTION(__x32_compat_sys##name, ERRNO);		\
-	asmlinkage long __x32_compat_sys##name(const struct pt_regs *regs)\
-	{								\
-		return __se_compat_sys##name(SC_X86_64_REGS_TO_ARGS(x,__VA_ARGS__));\
-	}
+	__SYS_STUBx(x32, compat_sys##name,				\
+		    SC_X86_64_REGS_TO_ARGS(x, __VA_ARGS__))
 
 #else /* CONFIG_X86_X32 */
 #define __X32_COMPAT_SYS_STUB0(x, name)
@@ -192,14 +196,9 @@ struct pt_regs;
  * to the i386 calling convention (bx, cx, dx, si, di, bp).
  */
 #define __SYSCALL_DEFINEx(x, name, ...)					\
-	asmlinkage long __x64_sys##name(const struct pt_regs *regs);	\
-	ALLOW_ERROR_INJECTION(__x64_sys##name, ERRNO);			\
 	static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__));	\
 	static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));\
-	asmlinkage long __x64_sys##name(const struct pt_regs *regs)	\
-	{								\
-		return __se_sys##name(SC_X86_64_REGS_TO_ARGS(x,__VA_ARGS__));\
-	}								\
+	__X64_SYS_STUBx(x, name, __VA_ARGS__)				\
 	__IA32_SYS_STUBx(x, name, __VA_ARGS__)				\
 	static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__))	\
 	{								\