arch/mn10300/mm/pgtable.c

   1 /* MN10300 Page table management
   2  *
   3  * Copyright (C) 2007 Matsushita Electric Industrial Co., Ltd.
   4  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   5  * Modified by David Howells (dhowells@redhat.com)
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public Licence
   9  * as published by the Free Software Foundation; either version
  10  * 2 of the Licence, or (at your option) any later version.
  11  */
  12 #include <linux/sched.h>
  13 #include <linux/kernel.h>
  14 #include <linux/errno.h>
  15 #include <linux/gfp.h>
  16 #include <linux/mm.h>
  17 #include <linux/swap.h>
  18 #include <linux/smp.h>
  19 #include <linux/highmem.h>
  20 #include <linux/pagemap.h>
  21 #include <linux/spinlock.h>
  22 #include <linux/quicklist.h>
  23
  24 #include <asm/pgtable.h>
  25 #include <asm/pgalloc.h>
  26 #include <asm/tlb.h>
  27 #include <asm/tlbflush.h>
  28
  29 /*
  30  * Associate a large virtual page frame with a given physical page frame
  31  * and protection flags for that frame. pfn is for the base of the page,
  32  * vaddr is what the page gets mapped to - both must be properly aligned.
  33  * The pmd must already be instantiated. Assumes PAE mode.
  34  */
  35 void set_pmd_pfn(unsigned long vaddr, unsigned long pfn, pgprot_t flags)
  36 {
  37         pgd_t *pgd;
  38         pud_t *pud;
  39         pmd_t *pmd;
  40
  41         if (vaddr & (PMD_SIZE-1)) {             /* vaddr is misaligned */
  42                 printk(KERN_ERR "set_pmd_pfn: vaddr misaligned\n");
  43                 return; /* BUG(); */
  44         }
  45         if (pfn & (PTRS_PER_PTE-1)) {           /* pfn is misaligned */
  46                 printk(KERN_ERR "set_pmd_pfn: pfn misaligned\n");
  47                 return; /* BUG(); */
  48         }
  49         pgd = swapper_pg_dir + pgd_index(vaddr);
  50         if (pgd_none(*pgd)) {
  51                 printk(KERN_ERR "set_pmd_pfn: pgd_none\n");
  52                 return; /* BUG(); */
  53         }
  54         pud = pud_offset(pgd, vaddr);
  55         pmd = pmd_offset(pud, vaddr);
  56         set_pmd(pmd, pfn_pmd(pfn, flags));
  57         /*
  58          * It's enough to flush this one mapping.
  59          * (PGE mappings get flushed as well)
  60          */
  61         local_flush_tlb_one(vaddr);
  62 }
  63
  64 pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
  65 {
  66         pte_t *pte = (pte_t *)__get_free_page(GFP_KERNEL);
  67         if (pte)
  68                 clear_page(pte);
  69         return pte;
  70 }
  71
  72 struct page *pte_alloc_one(struct mm_struct *mm, unsigned long address)
  73 {
  74         struct page *pte;
  75
  76 #ifdef CONFIG_HIGHPTE
  77         pte = alloc_pages(GFP_KERNEL|__GFP_HIGHMEM, 0);
  78 #else
  79         pte = alloc_pages(GFP_KERNEL, 0);
  80 #endif
  81         if (!pte)
  82                 return NULL;
  83         clear_highpage(pte);
  84         if (!pgtable_page_ctor(pte)) {
  85                 __free_page(pte);
  86                 return NULL;
  87         }
  88         return pte;
  89 }
  90
  91 /*
  92  * List of all pgd's needed for non-PAE so it can invalidate entries
  93  * in both cached and uncached pgd's; not needed for PAE since the
  94  * kernel pmd is shared. If PAE were not to share the pmd a similar
  95  * tactic would be needed. This is essentially codepath-based locking
  96  * against pageattr.c; it is the unique case in which a valid change
  97  * of kernel pagetables can't be lazily synchronized by vmalloc faults.
  98  * vmalloc faults work because attached pagetables are never freed.
  99  * If the locking proves to be non-performant, a ticketing scheme with
 100  * checks at dup_mmap(), exec(), and other mmlist addition points
 101  * could be used. The locking scheme was chosen on the basis of
 102  * manfred's recommendations and having no core impact whatsoever.
 103  * -- nyc
 104  */
 105 DEFINE_SPINLOCK(pgd_lock);
 106 struct page *pgd_list;
 107
 108 static inline void pgd_list_add(pgd_t *pgd)
 109 {
 110         struct page *page = virt_to_page(pgd);
 111         page->index = (unsigned long) pgd_list;
 112         if (pgd_list)
 113                 set_page_private(pgd_list, (unsigned long) &page->index);
 114         pgd_list = page;
 115         set_page_private(page, (unsigned long) &pgd_list);
 116 }
 117
 118 static inline void pgd_list_del(pgd_t *pgd)
 119 {
 120         struct page *next, **pprev, *page = virt_to_page(pgd);
 121         next = (struct page *) page->index;
 122         pprev = (struct page **) page_private(page);
 123         *pprev = next;
 124         if (next)
 125                 set_page_private(next, (unsigned long) pprev);
 126 }
 127
 128 void pgd_ctor(void *pgd)
 129 {
 130         unsigned long flags;
 131
 132         if (PTRS_PER_PMD == 1)
 133                 spin_lock_irqsave(&pgd_lock, flags);
 134
 135         memcpy((pgd_t *)pgd + USER_PTRS_PER_PGD,
 136                         swapper_pg_dir + USER_PTRS_PER_PGD,
 137                         (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
 138
 139         if (PTRS_PER_PMD > 1)
 140                 return;
 141
 142         pgd_list_add(pgd);
 143         spin_unlock_irqrestore(&pgd_lock, flags);
 144         memset(pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
 145 }
 146
 147 /* never called when PTRS_PER_PMD > 1 */
 148 void pgd_dtor(void *pgd)
 149 {
 150         unsigned long flags; /* can be called from interrupt context */
 151
 152         spin_lock_irqsave(&pgd_lock, flags);
 153         pgd_list_del(pgd);
 154         spin_unlock_irqrestore(&pgd_lock, flags);
 155 }
 156
 157 pgd_t *pgd_alloc(struct mm_struct *mm)
 158 {
 159         return quicklist_alloc(0, GFP_KERNEL, pgd_ctor);
 160 }
 161
 162 void pgd_free(struct mm_struct *mm, pgd_t *pgd)
 163 {
 164         quicklist_free(0, pgd_dtor, pgd);
 165 }
 166
 167 void __init pgtable_cache_init(void)
 168 {
 169 }
 170
 171 void check_pgt_cache(void)
 172 {
 173         quicklist_trim(0, pgd_dtor, 25, 16);
 174 }