1 /* SPDX-License-Identifier: GPL-2.0-only */
2 
3 #ifndef LINUX_RESUME_USER_MODE_H
4 #define LINUX_RESUME_USER_MODE_H
5 
6 #include <linux/sched.h>
7 #include <linux/task_work.h>
8 #include <linux/memcontrol.h>
9 #include <linux/rseq.h>
10 #include <linux/blk-cgroup.h>
11 
12 /**
13  * set_notify_resume - cause resume_user_mode_work() to be called
14  * @task:		task that will call resume_user_mode_work()
15  *
16  * Calling this arranges that @task will call resume_user_mode_work()
17  * before returning to user mode.  If it's already running in user mode,
18  * it will enter the kernel and call resume_user_mode_work() soon.
19  * If it's blocked, it will not be woken.
20  */
set_notify_resume(struct task_struct * task)21 static inline void set_notify_resume(struct task_struct *task)
22 {
23 	if (!test_and_set_tsk_thread_flag(task, TIF_NOTIFY_RESUME))
24 		kick_process(task);
25 }
26 
27 
28 /**
29  * resume_user_mode_work - Perform work before returning to user mode
30  * @regs:		user-mode registers of @current task
31  *
32  * This is called when %TIF_NOTIFY_RESUME has been set.  Now we are
33  * about to return to user mode, and the user state in @regs can be
34  * inspected or adjusted.  The caller in arch code has cleared
35  * %TIF_NOTIFY_RESUME before the call.  If the flag gets set again
36  * asynchronously, this will be called again before we return to
37  * user mode.
38  *
39  * Called without locks.
40  */
resume_user_mode_work(struct pt_regs * regs)41 static inline void resume_user_mode_work(struct pt_regs *regs)
42 {
43 	clear_thread_flag(TIF_NOTIFY_RESUME);
44 	/*
45 	 * This barrier pairs with task_work_add()->set_notify_resume() after
46 	 * hlist_add_head(task->task_works);
47 	 */
48 	smp_mb__after_atomic();
49 	if (unlikely(task_work_pending(current)))
50 		task_work_run();
51 
52 #ifdef CONFIG_KEYS_REQUEST_CACHE
53 	if (unlikely(current->cached_requested_key)) {
54 		key_put(current->cached_requested_key);
55 		current->cached_requested_key = NULL;
56 	}
57 #endif
58 
59 	mem_cgroup_handle_over_high(GFP_KERNEL);
60 	blkcg_maybe_throttle_current();
61 
62 	rseq_handle_notify_resume(NULL, regs);
63 }
64 
65 #endif /* LINUX_RESUME_USER_MODE_H */
66