arch/powerpc/mm/mmu_context_hash64.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/sched.h>
  14 #include <linux/kernel.h>
  15 #include <linux/errno.h>
  16 #include <linux/string.h>
  17 #include <linux/types.h>
  18 #include <linux/mm.h>
  19 #include <linux/spinlock.h>
  20 #include <linux/idr.h>
  21 #include <linux/export.h>
  22 #include <linux/gfp.h>
  23 #include <linux/slab.h>
  24
  25 #include <asm/mmu_context.h>
  26
  27 #include "icswx.h"
  28
  29 static DEFINE_SPINLOCK(mmu_context_lock);
  30 static DEFINE_IDA(mmu_context_ida);
  31
  32 int __init_new_context(void)
  33 {
  34         int index;
  35         int err;
  36
  37 again:
  38         if (!ida_pre_get(&mmu_context_ida, GFP_KERNEL))
  39                 return -ENOMEM;
  40
  41         spin_lock(&mmu_context_lock);
  42         err = ida_get_new_above(&mmu_context_ida, 1, &index);
  43         spin_unlock(&mmu_context_lock);
  44
  45         if (err == -EAGAIN)
  46                 goto again;
  47         else if (err)
  48                 return err;
  49
  50         if (index > MAX_USER_CONTEXT) {
  51                 spin_lock(&mmu_context_lock);
  52                 ida_remove(&mmu_context_ida, index);
  53                 spin_unlock(&mmu_context_lock);
  54                 return -ENOMEM;
  55         }
  56
  57         return index;
  58 }
  59 EXPORT_SYMBOL_GPL(__init_new_context);
  60
  61 int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
  62 {
  63         int index;
  64
  65         index = __init_new_context();
  66         if (index < 0)
  67                 return index;
  68
  69         /* The old code would re-promote on fork, we don't do that
  70          * when using slices as it could cause problem promoting slices
  71          * that have been forced down to 4K
  72          */
  73         if (slice_mm_new_context(mm))
  74                 slice_set_user_psize(mm, mmu_virtual_psize);
  75         subpage_prot_init_new_context(mm);
  76         mm->context.id = index;
  77 #ifdef CONFIG_PPC_ICSWX
  78         mm->context.cop_lockp = kmalloc(sizeof(spinlock_t), GFP_KERNEL);
  79         if (!mm->context.cop_lockp) {
  80                 __destroy_context(index);
  81                 subpage_prot_free(mm);
  82                 mm->context.id = MMU_NO_CONTEXT;
  83                 return -ENOMEM;
  84         }
  85         spin_lock_init(mm->context.cop_lockp);
  86 #endif /* CONFIG_PPC_ICSWX */
  87
  88         return 0;
  89 }
  90
  91 void __destroy_context(int context_id)
  92 {
  93         spin_lock(&mmu_context_lock);
  94         ida_remove(&mmu_context_ida, context_id);
  95         spin_unlock(&mmu_context_lock);
  96 }
  97 EXPORT_SYMBOL_GPL(__destroy_context);
  98
  99 void destroy_context(struct mm_struct *mm)
 100 {
 101 #ifdef CONFIG_PPC_ICSWX
 102         drop_cop(mm->context.acop, mm);
 103         kfree(mm->context.cop_lockp);
 104         mm->context.cop_lockp = NULL;
 105 #endif /* CONFIG_PPC_ICSWX */
 106         __destroy_context(mm->context.id);
 107         subpage_prot_free(mm);
 108         mm->context.id = MMU_NO_CONTEXT;
 109 }