edlp_d8/sites/all/modules/contrib/admin/permissions_filter/permissions_filter.module

<?php

use Drupal\Core\Form\FormStateInterface;
use Drupal\Core\Routing\RouteMatchInterface;

/**
 * Implements hook_help().
 */
function permissions_filter_help($route_name, RouteMatchInterface $route_match) {
  switch ($route_name) {
    // Main module help for the permissions_filter module.
    case 'help.page.permissions_filter':
      $output = '';
      $output .= '<h3>' . t('About') . '</h3>';
      $output .= '<p>' . t('Create a filter for permission page.') . '</p>';
      return $output;

    default:
  }
}

/**
 * Implements hook_form_alter() on behalf of permissions_filter.module.
 */
function permissions_filter_form_alter(&$form, FormStateInterface $form_state, $form_id) {
  if ($form_id == 'user_admin_permissions') {
    $form['filters'] = array(
      '#type' => 'container',
      '#attributes' => array(
        'class' => array('table-filter', 'js-show'),
      ),
      '#weight' => -1,
    );
    $form['filters']['search_permission'] = array(
      '#type' => 'search',
      '#title' => t('Enter a part of the Permission name or description'),
      '#title_display' => 'invisible',
      '#size' => 30,
      '#placeholder' => t('Filter by name or description'),
      '#description' => t('Enter a part of the permission'),
      '#attributes' => array(
        'class' => array('table-filter-text'),
        'data-table' => '#user-admin-permissions',
        'autocomplete' => 'off',
      ),
    );
    $form['#attached']['library'][] = 'permissions_filter/permissions_js';
  }
}