efi-stub: Fix get_efi_config_table on mixed-mode setups

Fix get_efi_config_table using the wrong structs when booting a
64 bit kernel on 32 bit firmware.

Fixes: 82d736ac ("Abstract out support for locating an EFI config table")
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-By: Matthew Garrett <mjg59@google.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

drivers/firmware/efi/libstub/efi-stub-helper.c

@@ -927,17 +927,33 @@ efi_status_t efi_exit_boot_services(efi_system_table_t *sys_table_arg,
 	return status;
 }
 
+#define GET_EFI_CONFIG_TABLE(bits)					\
+static void *get_efi_config_table##bits(efi_system_table_t *_sys_table,	\
+					efi_guid_t guid)		\
+{									\
+	efi_system_table_##bits##_t *sys_table;				\
+	efi_config_table_##bits##_t *tables;				\
+	int i;								\
+									\
+	sys_table = (typeof(sys_table))_sys_table;			\
+	tables = (typeof(tables))(unsigned long)sys_table->tables;	\
+									\
+	for (i = 0; i < sys_table->nr_tables; i++) {			\
+		if (efi_guidcmp(tables[i].guid, guid) != 0)		\
+			continue;					\
+									\
+		return (void *)(unsigned long)tables[i].table;		\
+	}								\
+									\
+	return NULL;							\
+}
+GET_EFI_CONFIG_TABLE(32)
+GET_EFI_CONFIG_TABLE(64)
+
 void *get_efi_config_table(efi_system_table_t *sys_table, efi_guid_t guid)
 {
-	efi_config_table_t *tables = (efi_config_table_t *)sys_table->tables;
-	int i;
-
-	for (i = 0; i < sys_table->nr_tables; i++) {
-		if (efi_guidcmp(tables[i].guid, guid) != 0)
-			continue;
-
-		return (void *)tables[i].table;
-	}
-
-	return NULL;
+	if (efi_is_64bit())
+		return get_efi_config_table64(sys_table, guid);
+	else
+		return get_efi_config_table32(sys_table, guid);
 }