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  * 256MB segment
  34  * The proto-VSID space has 2^(CONTEX_BITS + USER_ESID_BITS) - 1 segments
  35  * available for user mappings. Each segment contains 2^28 bytes. Each
  36  * context maps 2^46 bytes (64TB) so we can support 2^19-1 contexts
  37  * (19 == 37 + 28 - 46).
  38  */
  39 #define MAX_CONTEXT     ((1UL << CONTEXT_BITS) - 1)
  40
  41 int __init_new_context(void)
  42 {
  43         int index;
  44         int err;
  45
  46 again:
  47         if (!ida_pre_get(&mmu_context_ida, GFP_KERNEL))
  48                 return -ENOMEM;
  49
  50         spin_lock(&mmu_context_lock);
  51         err = ida_get_new_above(&mmu_context_ida, 1, &index);
  52         spin_unlock(&mmu_context_lock);
  53
  54         if (err == -EAGAIN)
  55                 goto again;
  56         else if (err)
  57                 return err;
  58
  59         if (index > MAX_CONTEXT) {
  60                 spin_lock(&mmu_context_lock);
  61                 ida_remove(&mmu_context_ida, index);
  62                 spin_unlock(&mmu_context_lock);
  63                 return -ENOMEM;
  64         }
  65
  66         return index;
  67 }
  68 EXPORT_SYMBOL_GPL(__init_new_context);
  69
  70 int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
  71 {
  72         int index;
  73
  74         index = __init_new_context();
  75         if (index < 0)
  76                 return index;
  77
  78         /* The old code would re-promote on fork, we don't do that
  79          * when using slices as it could cause problem promoting slices
  80          * that have been forced down to 4K
  81          */
  82         if (slice_mm_new_context(mm))
  83                 slice_set_user_psize(mm, mmu_virtual_psize);
  84         subpage_prot_init_new_context(mm);
  85         mm->context.id = index;
  86 #ifdef CONFIG_PPC_ICSWX
  87         mm->context.cop_lockp = kmalloc(sizeof(spinlock_t), GFP_KERNEL);
  88         if (!mm->context.cop_lockp) {
  89                 __destroy_context(index);
  90                 subpage_prot_free(mm);
  91                 mm->context.id = MMU_NO_CONTEXT;
  92                 return -ENOMEM;
  93         }
  94         spin_lock_init(mm->context.cop_lockp);
  95 #endif /* CONFIG_PPC_ICSWX */
  96
  97         return 0;
  98 }
  99
 100 void __destroy_context(int context_id)
 101 {
 102         spin_lock(&mmu_context_lock);
 103         ida_remove(&mmu_context_ida, context_id);
 104         spin_unlock(&mmu_context_lock);
 105 }
 106 EXPORT_SYMBOL_GPL(__destroy_context);
 107
 108 void destroy_context(struct mm_struct *mm)
 109 {
 110 #ifdef CONFIG_PPC_ICSWX
 111         drop_cop(mm->context.acop, mm);
 112         kfree(mm->context.cop_lockp);
 113         mm->context.cop_lockp = NULL;
 114 #endif /* CONFIG_PPC_ICSWX */
 115         __destroy_context(mm->context.id);
 116         subpage_prot_free(mm);
 117         mm->context.id = MMU_NO_CONTEXT;
 118 }