Custom filed for specific page templae in wordpress

/*Custom filed for specific page templae (about us)   */

function wpse70958_add_meta_boxes( $post ) {

global $post;

$page_template = get_post_meta( $post->ID, '_wp_page_template', true );

if ( 'about-page-template.php' == $page_template ) {
 
   add_meta_box( 'about_meta', 'About Details', 'about_meta_functions', 'page', 'normal', 'high' );
}

}

add_action( 'add_meta_boxes_page', 'wpse70958_add_meta_boxes' );

function about_meta_functions() {
        global $post;
     
        $our_mission= get_post_meta($post->ID, 'our_mission', true);
$our_vission= get_post_meta($post->ID, 'our_vission', true);

?>
<div class="row">
<div class="form-group col-sm-12">
    <label for="our mission" style="vertical-align:top;">Our Mission</label>
     
      <textarea rows="4" cols="100" name="our_mission" class="form-control">
<?php
            if(isset($our_mission)) {
                echo $our_mission;
            }
        ?>
</textarea>
 </div>
</div>

<div class="row">
<div class="form-group col-sm-12">

  <label for="our vission" style="vertical-align:top;">Our Vission</label>
     
      <textarea rows="4" cols="100" name="our_vission" class="form-control">
<?php
            if(isset($our_vission)) {
                echo $our_vission;
            }
        ?>
</textarea> 
</div>
</div>
  <?php

    }


 function about_meta_save($post_id, $post) {

    global $post;

update_post_meta($post->ID, 'our_mission', $_POST['our_mission']);
update_post_meta($post->ID, 'our_vission', $_POST['our_vission']);

}
add_action( 'admin_menu', 'about_meta' );
add_action( 'save_post', 'about_meta_save', 1, 2);