mm/mmu_context.c

   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  */
  22 void 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         /* Hold off tlb flush IPIs while switching mm's */
  29         local_irq_disable();
  30         active_mm = tsk->active_mm;
  31         if (active_mm != mm) {
  32                 mmgrab(mm);
  33                 tsk->active_mm = mm;
  34         }
  35         tsk->mm = mm;
  36         switch_mm_irqs_off(active_mm, mm, tsk);
  37         local_irq_enable();
  38         task_unlock(tsk);
  39 #ifdef finish_arch_post_lock_switch
  40         finish_arch_post_lock_switch();
  41 #endif
  42
  43         if (active_mm != mm)
  44                 mmdrop(active_mm);
  45 }
  46 EXPORT_SYMBOL_GPL(use_mm);
  47
  48 /*
  49  * unuse_mm
  50  *      Reverses the effect of use_mm, i.e. releases the
  51  *      specified mm context which was earlier taken on
  52  *      by the calling kernel thread
  53  *      (Note: this routine is intended to be called only
  54  *      from a kernel thread context)
  55  */
  56 void unuse_mm(struct mm_struct *mm)
  57 {
  58         struct task_struct *tsk = current;
  59
  60         task_lock(tsk);
  61         sync_mm_rss(mm);
  62         local_irq_disable();
  63         tsk->mm = NULL;
  64         /* active_mm is still 'mm' */
  65         enter_lazy_tlb(mm, tsk);
  66         local_irq_enable();
  67         task_unlock(tsk);
  68 }
  69 EXPORT_SYMBOL_GPL(unuse_mm);