1145332Smarcel// SPDX-License-Identifier: GPL-2.0-only 2145332Smarcel 3145332Smarcel#include <linux/user-return-notifier.h> 4145332Smarcel#include <linux/percpu.h> 5145332Smarcel#include <linux/sched.h> 6145332Smarcel#include <linux/export.h> 7145332Smarcel 8145332Smarcelstatic DEFINE_PER_CPU(struct hlist_head, return_notifier_list); 9145332Smarcel 10255164Sjhibbits/* 11255164Sjhibbits * Request a notification when the current cpu returns to userspace. Must be 12233628Sfabient * called in atomic context. The notifier will also be called in atomic 13147191Sjkoshy * context. 14147191Sjkoshy */ 15147191Sjkoshyvoid user_return_notifier_register(struct user_return_notifier *urn) 16147191Sjkoshy{ 17147191Sjkoshy set_tsk_thread_flag(current, TIF_USER_RETURN_NOTIFY); 18147191Sjkoshy hlist_add_head(&urn->link, this_cpu_ptr(&return_notifier_list)); 19147191Sjkoshy} 20147191SjkoshyEXPORT_SYMBOL_GPL(user_return_notifier_register); 21147191Sjkoshy 22147191Sjkoshy/* 23228869Sjhibbits * Removes a registered user return notifier. Must be called from atomic 24228869Sjhibbits * context, and from the same cpu registration occurred in. 25228869Sjhibbits */ 26228869Sjhibbitsvoid user_return_notifier_unregister(struct user_return_notifier *urn) 27147191Sjkoshy{ 28228869Sjhibbits hlist_del(&urn->link); 29147191Sjkoshy if (hlist_empty(this_cpu_ptr(&return_notifier_list))) 30147191Sjkoshy clear_tsk_thread_flag(current, TIF_USER_RETURN_NOTIFY); 31174405Sjkoshy} 32174405SjkoshyEXPORT_SYMBOL_GPL(user_return_notifier_unregister); 33174405Sjkoshy 34174405Sjkoshy/* Calls registered user return notifiers */ 35147191Sjkoshyvoid fire_user_return_notifiers(void) 36147191Sjkoshy{ 37145332Smarcel struct user_return_notifier *urn; 38 struct hlist_node *tmp2; 39 struct hlist_head *head; 40 41 head = &get_cpu_var(return_notifier_list); 42 hlist_for_each_entry_safe(urn, tmp2, head, link) 43 urn->on_user_return(urn); 44 put_cpu_var(return_notifier_list); 45} 46