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 #include <asm/pgalloc.h>
  27
  28 #include "icswx.h"
  29
  30 static DEFINE_SPINLOCK(mmu_context_lock);
  31 static DEFINE_IDA(mmu_context_ida);
  32
  33 int __init_new_context(void)
  34 {
  35         int index;
  36         int err;
  37
  38 again:
  39         if (!ida_pre_get(&mmu_context_ida, GFP_KERNEL))
  40                 return -ENOMEM;
  41
  42         spin_lock(&mmu_context_lock);
  43         err = ida_get_new_above(&mmu_context_ida, 1, &index);
  44         spin_unlock(&mmu_context_lock);
  45
  46         if (err == -EAGAIN)
  47                 goto again;
  48         else if (err)
  49                 return err;
  50
  51         if (index > MAX_USER_CONTEXT) {
  52                 spin_lock(&mmu_context_lock);
  53                 ida_remove(&mmu_context_ida, index);
  54                 spin_unlock(&mmu_context_lock);
  55                 return -ENOMEM;
  56         }
  57
  58         return index;
  59 }
  60 EXPORT_SYMBOL_GPL(__init_new_context);
  61
  62 int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
  63 {
  64         int index;
  65
  66         index = __init_new_context();
  67         if (index < 0)
  68                 return index;
  69
  70         /* The old code would re-promote on fork, we don't do that
  71          * when using slices as it could cause problem promoting slices
  72          * that have been forced down to 4K
  73          */
  74         if (slice_mm_new_context(mm))
  75                 slice_set_user_psize(mm, mmu_virtual_psize);
  76         subpage_prot_init_new_context(mm);
  77         mm->context.id = index;
  78 #ifdef CONFIG_PPC_ICSWX
  79         mm->context.cop_lockp = kmalloc(sizeof(spinlock_t), GFP_KERNEL);
  80         if (!mm->context.cop_lockp) {
  81                 __destroy_context(index);
  82                 subpage_prot_free(mm);
  83                 mm->context.id = MMU_NO_CONTEXT;
  84                 return -ENOMEM;
  85         }
  86         spin_lock_init(mm->context.cop_lockp);
  87 #endif /* CONFIG_PPC_ICSWX */
  88
  89 #ifdef CONFIG_PPC_64K_PAGES
  90         mm->context.pte_frag = NULL;
  91 #endif
  92         return 0;
  93 }
  94
  95 void __destroy_context(int context_id)
  96 {
  97         spin_lock(&mmu_context_lock);
  98         ida_remove(&mmu_context_ida, context_id);
  99         spin_unlock(&mmu_context_lock);
 100 }
 101 EXPORT_SYMBOL_GPL(__destroy_context);
 102
 103 #ifdef CONFIG_PPC_64K_PAGES
 104 static void destroy_pagetable_page(struct mm_struct *mm)
 105 {
 106         int count;
 107         void *pte_frag;
 108         struct page *page;
 109
 110         pte_frag = mm->context.pte_frag;
 111         if (!pte_frag)
 112                 return;
 113
 114         page = virt_to_page(pte_frag);
 115         /* drop all the pending references */
 116         count = ((unsigned long)pte_frag & ~PAGE_MASK) >> PTE_FRAG_SIZE_SHIFT;
 117         /* We allow PTE_FRAG_NR fragments from a PTE page */
 118         count = atomic_sub_return(PTE_FRAG_NR - count, &page->_count);
 119         if (!count) {
 120                 pgtable_page_dtor(page);
 121                 free_hot_cold_page(page, 0);
 122         }
 123 }
 124
 125 #else
 126 static inline void destroy_pagetable_page(struct mm_struct *mm)
 127 {
 128         return;
 129 }
 130 #endif
 131
 132
 133 void destroy_context(struct mm_struct *mm)
 134 {
 135
 136 #ifdef CONFIG_PPC_ICSWX
 137         drop_cop(mm->context.acop, mm);
 138         kfree(mm->context.cop_lockp);
 139         mm->context.cop_lockp = NULL;
 140 #endif /* CONFIG_PPC_ICSWX */
 141
 142         destroy_pagetable_page(mm);
 143         __destroy_context(mm->context.id);
 144         subpage_prot_free(mm);
 145         mm->context.id = MMU_NO_CONTEXT;
 146 }