efi_loader: execute efi_save_gd() first

If DEBUG is defined we may be calling EFI_CALL already during the
initialization of the EFI subsystem. We must make sure efi_save_gd() has
already been called at that moment.

Anyway it is better to have this call in one location instead of three.

This fixes an illegal memory access occurring since 4e6b5d6503ce
("efi_loader: create root node") with DEBUG = 1.

Fixes: 4e6b5d6503ce ("efi_loader: create root node")
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Alexander Graf <agraf@suse.de>

cmd/bootefi.c

@@ -40,6 +40,13 @@ efi_status_t efi_init_obj_list(void)
 {
 	efi_status_t ret = EFI_SUCCESS;
 
+	/*
+	 * On the ARM architecture gd is mapped to a fixed register (r9 or x18).
+	 * As this register may be overwritten by an EFI payload we save it here
+	 * and restore it on every callback entered.
+	 */
+	efi_save_gd();
+
 	/* Initialize once only */
 	if (efi_obj_list_initialized != OBJ_LIST_NOT_INITIALIZED)
 		return efi_obj_list_initialized;
@@ -374,12 +381,6 @@ static efi_status_t do_bootefi_exec(void *efi,
 	if (ret != EFI_SUCCESS)
 		goto exit;
 
-	/*
-	 * gd lives in a fixed register which may get clobbered while we execute
-	 * the payload. So save it here and restore it on every callback entry
-	 */
-	efi_save_gd();
-
 	/* Transfer environment variable bootargs as load options */
 	set_load_options(loaded_image_info, "bootargs");
 	/* Load the EFI payload */
@@ -460,12 +461,6 @@ static int do_bootefi_bootmgr_exec(void)
 	void *addr;
 	efi_status_t r;
 
-	/*
-	 * gd lives in a fixed register which may get clobbered while we execute
-	 * the payload. So save it here and restore it on every callback entry
-	 */
-	efi_save_gd();
-
 	addr = efi_bootmgr_load(&device_path, &file_path);
 	if (!addr)
 		return 1;
@@ -547,11 +542,6 @@ static int do_bootefi(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 		if (r != EFI_SUCCESS)
 			return CMD_RET_FAILURE;
 
-		/*
-		 * gd lives in a fixed register which may get clobbered while we
-		 * execute the payload. So save it here and restore it on every
-		 * callback entry
-		 */
 		efi_save_gd();
 		/* Transfer environment variable efi_selftest as load options */
 		set_load_options(loaded_image_info, "efi_selftest");