efi/runtime-wrappers: Remove duplicated macro for service returning void

__efi_call_virt() exists as an alternative for efi_call_virt() for the
sole reason that ResetSystem() returns void, and so we cannot use a call
to it in the RHS of an assignment.

Given that there is only a single user, let's drop the macro, and expand
it into the caller. That way, the remaining macro can be tightened
somewhat in terms of type safety too.

Note that the use of typeof() on the runtime service invocation does not
result in an actual call being made, but it does require a few pointer
types to be fixed up and converted into the proper function pointer
prototypes.

Signed-off-by: Ard Biesheuvel <[e-mail]>

arch/x86/include/asm/uv/bios.h

···
  * Copyright (c) Russ Anderson <[e-mail]>
  */
 
+#include <linux/efi.h>
 #include <linux/rtc.h>
 
 /*
···
 struct uv_systab {
 	char signature[4];	/* must be UV_SYSTAB_SIG */
 	u32 revision;		/* distinguish different firmware revs */
-	u64 function;		/* BIOS runtime callback function ptr */
+	u64 (__efiapi *function)(enum uv_bios_cmd, ...);
+				/* BIOS runtime callback function ptr */
 	u32 size;		/* systab size (starting with _VERSION_UV4) */
 	struct {
 		u32 type:8;	/* type of entry */

drivers/acpi/prmt.c

···
 
 struct prm_handler_info {
 	guid_t guid;
-	void *handler_addr;
+	efi_status_t (__efiapi *handler_addr)(u64, void *);
 	u64 static_data_buffer_addr;
 	u64 acpi_param_buffer_addr;
 

drivers/firmware/efi/runtime-wrappers.c

···
  */
 #define efi_call_virt(f, args...)   \
 	efi_call_virt_pointer(efi.runtime, f, args)
-#define __efi_call_virt(f, args...) \
-	__efi_call_virt_pointer(efi.runtime, f, args)
 
 union efi_rts_args {
 	struct {
···
 			"could not get exclusive access to the firmware\n");
 		return;
 	}
+
+	arch_efi_call_virt_setup();
 	efi_rts_work.efi_rts_id = EFI_RESET_SYSTEM;
-	__efi_call_virt(reset_system, reset_type, status, data_size, data);
+	arch_efi_call_virt(efi.runtime, reset_system, reset_type, status,
+			   data_size, data);
+	arch_efi_call_virt_teardown();
+
 	up(&efi_runtime_lock);
 }
 

include/linux/efi.h

···
 #define arch_efi_call_virt(p, f, args...)	((p)->f(args))
 
 /*
- * Arch code can implement the following three template macros, avoiding
- * reptition for the void/non-void return cases of {__,}efi_call_virt():
+ * Arch code must implement the following three routines:
  *
  *  * arch_efi_call_virt_setup()
  *
···
  *
  *  * arch_efi_call_virt()
  *
- *    Performs the call. The last expression in the macro must be the call
- *    itself, allowing the logic to be shared by the void and non-void
- *    cases.
+ *    Performs the call. This routine takes a variable number of arguments so
+ *    it must be implemented as a variadic preprocessor macro.
  *
  *  * arch_efi_call_virt_teardown()
  *
···
 
 #define efi_call_virt_pointer(p, f, args...)				\
 ({									\
-	efi_status_t __s;						\
+	typeof((p)->f(args)) __s;					\
 	unsigned long __flags;						\
 									\
 	arch_efi_call_virt_setup();					\
···
 	arch_efi_call_virt_teardown();					\
 									\
 	__s;								\
-})
-
-#define __efi_call_virt_pointer(p, f, args...)				\
-({									\
-	unsigned long __flags;						\
-									\
-	arch_efi_call_virt_setup();					\
-									\
-	__flags = efi_call_virt_save_flags();				\
-	arch_efi_call_virt(p, f, args);					\
-	efi_call_virt_check_flags(__flags, __stringify(f));		\
-									\
-	arch_efi_call_virt_teardown();					\
 })
 
 #define EFI_RANDOM_SEED_SIZE		32U // BLAKE2S_HASH_SIZE