x86/entry: Refactor SYS_NI macros

Pull the common code out from the SYS_NI macros into a new __SYS_NI 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/20200313195144.164260-5-brgerst@gmail.com

arch/x86/include/asm/syscall_wrapper.h

@@ -42,6 +42,9 @@ struct pt_regs;
 		return sys_ni_syscall();				\
 	}
 
+#define __SYS_NI(abi, name)						\
+	SYSCALL_ALIAS(__##abi##_##name, sys_ni_posix_timers)
+
 #ifdef CONFIG_X86_64
 #define __X64_SYS_STUB0(name)						\
 	__SYS_STUB0(x64, sys_##name)
@@ -52,10 +55,14 @@ struct pt_regs;
 
 #define __X64_COND_SYSCALL(name)					\
 	__COND_SYSCALL(x64, sys_##name)
+
+#define __X64_SYS_NI(name)						\
+	__SYS_NI(x64, sys_##name)
 #else /* CONFIG_X86_64 */
 #define __X64_SYS_STUB0(name)
 #define __X64_SYS_STUBx(x, name, ...)
 #define __X64_COND_SYSCALL(name)
+#define __X64_SYS_NI(name)
 #endif /* CONFIG_X86_64 */
 
 #ifdef CONFIG_IA32_EMULATION
@@ -77,6 +84,9 @@ struct pt_regs;
 #define __IA32_COMPAT_COND_SYSCALL(name)				\
 	__COND_SYSCALL(ia32, compat_sys_##name)
 
+#define __IA32_COMPAT_SYS_NI(name)					\
+	__SYS_NI(ia32, compat_sys_##name)
+
 #define __IA32_SYS_STUB0(name)						\
 	__SYS_STUB0(ia32, sys_##name)
 
@@ -87,17 +97,17 @@ struct pt_regs;
 #define __IA32_COND_SYSCALL(name)					\
 	__COND_SYSCALL(ia32, sys_##name)
 
-#define SYS_NI(name)							\
-	SYSCALL_ALIAS(__x64_sys_##name, sys_ni_posix_timers);		\
-	SYSCALL_ALIAS(__ia32_sys_##name, sys_ni_posix_timers)
-
+#define __IA32_SYS_NI(name)						\
+	__SYS_NI(ia32, sys_##name)
 #else /* CONFIG_IA32_EMULATION */
 #define __IA32_COMPAT_SYS_STUB0(name)
 #define __IA32_COMPAT_SYS_STUBx(x, name, ...)
 #define __IA32_COMPAT_COND_SYSCALL(name)
+#define __IA32_COMPAT_SYS_NI(name)
 #define __IA32_SYS_STUB0(name)
 #define __IA32_SYS_STUBx(x, name, ...)
 #define __IA32_COND_SYSCALL(name)
+#define __IA32_SYS_NI(name)
 #endif /* CONFIG_IA32_EMULATION */
 
 
@@ -116,10 +126,14 @@ struct pt_regs;
 
 #define __X32_COMPAT_COND_SYSCALL(name)					\
 	__COND_SYSCALL(x32, compat_sys_##name)
+
+#define __X32_COMPAT_SYS_NI(name)					\
+	__SYS_NI(x32, compat_sys_##name)
 #else /* CONFIG_X86_X32 */
 #define __X32_COMPAT_SYS_STUB0(name)
 #define __X32_COMPAT_SYS_STUBx(x, name, ...)
 #define __X32_COMPAT_COND_SYSCALL(name)
+#define __X32_COMPAT_SYS_NI(name)
 #endif /* CONFIG_X86_X32 */
 
 
@@ -158,8 +172,8 @@ struct pt_regs;
 	__X32_COMPAT_COND_SYSCALL(name)
 
 #define COMPAT_SYS_NI(name)						\
-	SYSCALL_ALIAS(__ia32_compat_sys_##name, sys_ni_posix_timers);	\
-	SYSCALL_ALIAS(__x32_compat_sys_##name, sys_ni_posix_timers)
+	__IA32_COMPAT_SYS_NI(name)					\
+	__X32_COMPAT_SYS_NI(name)
 
 #endif /* CONFIG_COMPAT */
 
@@ -231,9 +245,9 @@ struct pt_regs;
 	__X64_COND_SYSCALL(name)					\
 	__IA32_COND_SYSCALL(name)
 
-#ifndef SYS_NI
-#define SYS_NI(name) SYSCALL_ALIAS(__x64_sys_##name, sys_ni_posix_timers);
-#endif
+#define SYS_NI(name)							\
+	__X64_SYS_NI(name)						\
+	__IA32_SYS_NI(name)
 
 
 /*