x86/efistub: Enable SMBIOS protocol handling for x86

The smbios.c source file is not currently included in the x86 build, and
before we can do so, it needs some tweaks to build correctly in
combination with the EFI mixed mode support.

Reviewed-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

Author: ardbiesheuvel

arch/x86/include/asm/efi.h

@@ -229,7 +229,8 @@ static inline bool efi_is_native(void)
 
 static inline void *efi64_zero_upper(void *p)
 {
-	((u32 *)p)[1] = 0;
+	if (p)
+		((u32 *)p)[1] = 0;
 	return p;
 }
 
@@ -315,6 +316,10 @@ static inline u32 efi64_convert_status(efi_status_t status)
 #define __efi64_argmap_clear_memory_attributes(protocol, phys, size, flags) \
 	((protocol), __efi64_split(phys), __efi64_split(size), __efi64_split(flags))
 
+/* EFI SMBIOS protocol */
+#define __efi64_argmap_get_next(protocol, smbioshandle, type, record, phandle) \
+	((protocol), (smbioshandle), (type), efi64_zero_upper(record), \
+	 efi64_zero_upper(phandle))
 /*
  * The macros below handle the plumbing for the argument mapping. To add a
  * mapping for a specific EFI method, simply define a macro

drivers/firmware/efi/libstub/Makefile

@@ -76,7 +76,7 @@ lib-$(CONFIG_EFI_GENERIC_STUB)	+= efi-stub.o string.o intrinsics.o systable.o \
 
 lib-$(CONFIG_ARM)		+= arm32-stub.o
 lib-$(CONFIG_ARM64)		+= kaslr.o arm64.o arm64-stub.o smbios.o
-lib-$(CONFIG_X86)		+= x86-stub.o
+lib-$(CONFIG_X86)		+= x86-stub.o smbios.o
 lib-$(CONFIG_X86_64)		+= x86-5lvl.o
 lib-$(CONFIG_RISCV)		+= kaslr.o riscv.o riscv-stub.o
 lib-$(CONFIG_LOONGARCH)		+= loongarch.o loongarch-stub.o

drivers/firmware/efi/libstub/smbios.c

@@ -6,20 +6,31 @@
 
 #include "efistub.h"
 
-typedef struct efi_smbios_protocol efi_smbios_protocol_t;
-
-struct efi_smbios_protocol {
-	efi_status_t (__efiapi *add)(efi_smbios_protocol_t *, efi_handle_t,
-				     u16 *, struct efi_smbios_record *);
-	efi_status_t (__efiapi *update_string)(efi_smbios_protocol_t *, u16 *,
-					       unsigned long *, u8 *);
-	efi_status_t (__efiapi *remove)(efi_smbios_protocol_t *, u16);
-	efi_status_t (__efiapi *get_next)(efi_smbios_protocol_t *, u16 *, u8 *,
-					  struct efi_smbios_record **,
-					  efi_handle_t *);
-
-	u8 major_version;
-	u8 minor_version;
+typedef union efi_smbios_protocol efi_smbios_protocol_t;
+
+union efi_smbios_protocol {
+	struct {
+		efi_status_t (__efiapi *add)(efi_smbios_protocol_t *, efi_handle_t,
+					     u16 *, struct efi_smbios_record *);
+		efi_status_t (__efiapi *update_string)(efi_smbios_protocol_t *, u16 *,
+						       unsigned long *, u8 *);
+		efi_status_t (__efiapi *remove)(efi_smbios_protocol_t *, u16);
+		efi_status_t (__efiapi *get_next)(efi_smbios_protocol_t *, u16 *, u8 *,
+						  struct efi_smbios_record **,
+						  efi_handle_t *);
+
+		u8 major_version;
+		u8 minor_version;
+	};
+	struct {
+		u32 add;
+		u32 update_string;
+		u32 remove;
+		u32 get_next;
+
+		u8 major_version;
+		u8 minor_version;
+	} mixed_mode;
 };
 
 const struct efi_smbios_record *efi_get_smbios_record(u8 type)

include/linux/efi.h

@@ -74,10 +74,10 @@ typedef void *efi_handle_t;
  */
 typedef guid_t efi_guid_t __aligned(__alignof__(u32));
 
-#define EFI_GUID(a, b, c, d...) (efi_guid_t){ {					\
+#define EFI_GUID(a, b, c, d...) ((efi_guid_t){ {				\
 	(a) & 0xff, ((a) >> 8) & 0xff, ((a) >> 16) & 0xff, ((a) >> 24) & 0xff,	\
 	(b) & 0xff, ((b) >> 8) & 0xff,						\
-	(c) & 0xff, ((c) >> 8) & 0xff, d } }
+	(c) & 0xff, ((c) >> 8) & 0xff, d } })
 
 /*
  * Generic EFI table header