x86/asmlinkage: Fix warning in xen asmlinkage change

Current code uses asmlinkage for functions without arguments.
This adds an implicit regparm(0) which creates a warning
when assigning the function to pointers.

Use __visible for the functions without arguments.
This avoids having to add regparm(0) to function pointers.
Since they have no arguments it does not make any difference.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Link: http://lkml.kernel.org/r/1377115662-4865-1-git-send-email-andi@firstfloor.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/xen/xen-ops.h

@@ -105,7 +105,7 @@ static inline void __init xen_init_apic(void)
 /* Declare an asm function, along with symbols needed to make it
    inlineable */
 #define DECL_ASM(ret, name, ...)		\
-	asmlinkage ret name(__VA_ARGS__);	\
+	__visible ret name(__VA_ARGS__);	\
 	extern char name##_end[] __visible;	\
 	extern char name##_reloc[] __visible
 
@@ -115,11 +115,11 @@ DECL_ASM(unsigned long, xen_save_fl_direct, void);
 DECL_ASM(void, xen_restore_fl_direct, unsigned long);
 
 /* These are not functions, and cannot be called normally */
-asmlinkage void xen_iret(void);
-asmlinkage void xen_sysexit(void);
-asmlinkage void xen_sysret32(void);
-asmlinkage void xen_sysret64(void);
-asmlinkage void xen_adjust_exception_frame(void);
+__visible void xen_iret(void);
+__visible void xen_sysexit(void);
+__visible void xen_sysret32(void);
+__visible void xen_sysret64(void);
+__visible void xen_adjust_exception_frame(void);
 
 extern int xen_panic_handler_init(void);