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 /*
  33  * The proto-VSID space has 2^35 - 1 segments available for user mappings.
  34  * Each segment contains 2^28 bytes.  Each context maps 2^44 bytes,
  35  * so we can support 2^19-1 contexts (19 == 35 + 28 - 44).
  36  */
  37 #define MAX_CONTEXT     ((1UL << 19) - 1)
  38
  39 int __init_new_context(void)
  40 {
  41         int index;
  42         int err;
  43
  44 again:
  45         if (!ida_pre_get(&mmu_context_ida, GFP_KERNEL))
  46                 return -ENOMEM;
  47
  48         spin_lock(&mmu_context_lock);
  49         err = ida_get_new_above(&mmu_context_ida, 1, &index);
  50         spin_unlock(&mmu_context_lock);
  51
  52         if (err == -EAGAIN)
  53                 goto again;
  54         else if (err)
  55                 return err;
  56
  57         if (index > MAX_CONTEXT) {
  58                 spin_lock(&mmu_context_lock);
  59                 ida_remove(&mmu_context_ida, index);
  60                 spin_unlock(&mmu_context_lock);
  61                 return -ENOMEM;
  62         }
  63
  64         return index;
  65 }
  66 EXPORT_SYMBOL_GPL(__init_new_context);
  67
  68 int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
  69 {
  70         int index;
  71
  72         index = __init_new_context();
  73         if (index < 0)
  74                 return index;
  75
  76         /* The old code would re-promote on fork, we don't do that
  77          * when using slices as it could cause problem promoting slices
  78          * that have been forced down to 4K
  79          */
  80         if (slice_mm_new_context(mm))
  81                 slice_set_user_psize(mm, mmu_virtual_psize);
  82         subpage_prot_init_new_context(mm);
  83         mm->context.id = index;
  84 #ifdef CONFIG_PPC_ICSWX
  85         mm->context.cop_lockp = kmalloc(sizeof(spinlock_t), GFP_KERNEL);
  86         if (!mm->context.cop_lockp) {
  87                 __destroy_context(index);
  88                 subpage_prot_free(mm);
  89                 mm->context.id = MMU_NO_CONTEXT;
  90                 return -ENOMEM;
  91         }
  92         spin_lock_init(mm->context.cop_lockp);
  93 #endif /* CONFIG_PPC_ICSWX */
  94
  95         return 0;
  96 }
  97
  98 void __destroy_context(int context_id)
  99 {
 100         spin_lock(&mmu_context_lock);
 101         ida_remove(&mmu_context_ida, context_id);
 102         spin_unlock(&mmu_context_lock);
 103 }
 104 EXPORT_SYMBOL_GPL(__destroy_context);
 105
 106 void destroy_context(struct mm_struct *mm)
 107 {
 108 #ifdef CONFIG_PPC_ICSWX
 109         drop_cop(mm->context.acop, mm);
 110         kfree(mm->context.cop_lockp);
 111         mm->context.cop_lockp = NULL;
 112 #endif /* CONFIG_PPC_ICSWX */
 113         __destroy_context(mm->context.id);
 114         subpage_prot_free(mm);
 115         mm->context.id = MMU_NO_CONTEXT;
 116 }