1/* Copyright (C) 2009 Red Hat, Inc.
 2 *
 3 * See ../COPYING for licensing terms.
 4 */
 5
 6#include <linux/mm.h>
 7#include <linux/sched.h>
 8#include <linux/sched/mm.h>
 9#include <linux/sched/task.h>
10#include <linux/mmu_context.h>
11#include <linux/export.h>
12
13#include <asm/mmu_context.h>
14
15/*
16 * use_mm
17 *	Makes the calling kernel thread take on the specified
18 *	mm context.
19 *	(Note: this routine is intended to be called only
20 *	from a kernel thread context)
21 */
22void use_mm(struct mm_struct *mm)
23{
24	struct mm_struct *active_mm;
25	struct task_struct *tsk = current;
26
27	task_lock(tsk);
28	active_mm = tsk->active_mm;
29	if (active_mm != mm) {
30		mmgrab(mm);
31		tsk->active_mm = mm;
32	}
33	tsk->mm = mm;
34	switch_mm(active_mm, mm, tsk);
35	task_unlock(tsk);
36#ifdef finish_arch_post_lock_switch
37	finish_arch_post_lock_switch();
38#endif
39
40	if (active_mm != mm)
41		mmdrop(active_mm);
42}
43EXPORT_SYMBOL_GPL(use_mm);
44
45/*
46 * unuse_mm
47 *	Reverses the effect of use_mm, i.e. releases the
48 *	specified mm context which was earlier taken on
49 *	by the calling kernel thread
50 *	(Note: this routine is intended to be called only
51 *	from a kernel thread context)
52 */
53void unuse_mm(struct mm_struct *mm)
54{
55	struct task_struct *tsk = current;
56
57	task_lock(tsk);
58	sync_mm_rss(mm);
59	tsk->mm = NULL;
60	/* active_mm is still 'mm' */
61	enter_lazy_tlb(mm, tsk);
62	task_unlock(tsk);
63}
64EXPORT_SYMBOL_GPL(unuse_mm);