efi/libstub: Expose LocateDevicePath boot service

We will be adding support for loading the initrd from a GUIDed
device path in a subsequent patch, so update the prototype of
the LocateDevicePath() boot service to make it callable from
our code.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

arch/x86/include/asm/efi.h

@@ -283,6 +283,9 @@ static inline void *efi64_zero_upper(void *p)
 #define __efi64_argmap_locate_protocol(protocol, reg, interface)	\
 	((protocol), (reg), efi64_zero_upper(interface))
 
+#define __efi64_argmap_locate_device_path(protocol, path, handle)	\
+	((protocol), (path), efi64_zero_upper(handle))
+
 /* PCI I/O */
 #define __efi64_argmap_get_location(protocol, seg, bus, dev, func)	\
 	((protocol), efi64_zero_upper(seg), efi64_zero_upper(bus),	\

drivers/firmware/efi/libstub/efistub.h

@@ -100,6 +100,8 @@ struct efi_boot_memmap {
 	unsigned long		*buff_size;
 };
 
+typedef struct efi_generic_dev_path efi_device_path_protocol_t;
+
 /*
  * EFI Boot Services table
  */
@@ -134,7 +136,9 @@ union efi_boot_services {
 		efi_status_t (__efiapi *locate_handle)(int, efi_guid_t *,
 						       void *, unsigned long *,
 						       efi_handle_t *);
-		void *locate_device_path;
+		efi_status_t (__efiapi *locate_device_path)(efi_guid_t *,
+							    efi_device_path_protocol_t **,
+							    efi_handle_t *);
 		efi_status_t (__efiapi *install_configuration_table)(efi_guid_t *,
 								     void *);
 		void *load_image;