arch/powerpc/mm/mmu_context_64.c

   1 /*
   2  *  MMU context allocation for 64-bit kernels.
   3  *
   4  *  Copyright (C) 2004 Anton Blanchard, IBM Corp. <anton@samba.org>
   5  *
   6  *  This program is free software; you can redistribute it and/or
   7  *  modify it under the terms of the GNU General Public License
   8  *  as published by the Free Software Foundation; either version
   9  *  2 of the License, or (at your option) any later version.
  10  *
  11  */
  12
  13 #include <linux/config.h>
  14 #include <linux/sched.h>
  15 #include <linux/kernel.h>
  16 #include <linux/errno.h>
  17 #include <linux/string.h>
  18 #include <linux/types.h>
  19 #include <linux/mm.h>
  20 #include <linux/spinlock.h>
  21 #include <linux/idr.h>
  22
  23 #include <asm/mmu_context.h>
  24
  25 static DEFINE_SPINLOCK(mmu_context_lock);
  26 static DEFINE_IDR(mmu_context_idr);
  27
  28 int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
  29 {
  30         int index;
  31         int err;
  32
  33 again:
  34         if (!idr_pre_get(&mmu_context_idr, GFP_KERNEL))
  35                 return -ENOMEM;
  36
  37         spin_lock(&mmu_context_lock);
  38         err = idr_get_new_above(&mmu_context_idr, NULL, 1, &index);
  39         spin_unlock(&mmu_context_lock);
  40
  41         if (err == -EAGAIN)
  42                 goto again;
  43         else if (err)
  44                 return err;
  45
  46         if (index > MAX_CONTEXT) {
  47                 idr_remove(&mmu_context_idr, index);
  48                 return -ENOMEM;
  49         }
  50
  51         mm->context.id = index;
  52
  53         return 0;
  54 }
  55
  56 void destroy_context(struct mm_struct *mm)
  57 {
  58         spin_lock(&mmu_context_lock);
  59         idr_remove(&mmu_context_idr, mm->context.id);
  60         spin_unlock(&mmu_context_lock);
  61
  62         mm->context.id = NO_CONTEXT;
  63 }