linux/arch/mn10300/mm/pgtable.c
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   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/mm.h>
  16#include <linux/swap.h>
  17#include <linux/smp.h>
  18#include <linux/highmem.h>
  19#include <linux/slab.h>
  20#include <linux/pagemap.h>
  21#include <linux/spinlock.h>
  22#include <linux/quicklist.h>
  23
  24#include <asm/system.h>
  25#include <asm/pgtable.h>
  26#include <asm/pgalloc.h>
  27#include <asm/tlb.h>
  28#include <asm/tlbflush.h>
  29
  30/*
  31 * Associate a large virtual page frame with a given physical page frame
  32 * and protection flags for that frame. pfn is for the base of the page,
  33 * vaddr is what the page gets mapped to - both must be properly aligned.
  34 * The pmd must already be instantiated. Assumes PAE mode.
  35 */
  36void set_pmd_pfn(unsigned long vaddr, unsigned long pfn, pgprot_t flags)
  37{
  38        pgd_t *pgd;
  39        pud_t *pud;
  40        pmd_t *pmd;
  41
  42        if (vaddr & (PMD_SIZE-1)) {             /* vaddr is misaligned */
  43                printk(KERN_ERR "set_pmd_pfn: vaddr misaligned\n");
  44                return; /* BUG(); */
  45        }
  46        if (pfn & (PTRS_PER_PTE-1)) {           /* pfn is misaligned */
  47                printk(KERN_ERR "set_pmd_pfn: pfn misaligned\n");
  48                return; /* BUG(); */
  49        }
  50        pgd = swapper_pg_dir + pgd_index(vaddr);
  51        if (pgd_none(*pgd)) {
  52                printk(KERN_ERR "set_pmd_pfn: pgd_none\n");
  53                return; /* BUG(); */
  54        }
  55        pud = pud_offset(pgd, vaddr);
  56        pmd = pmd_offset(pud, vaddr);
  57        set_pmd(pmd, pfn_pmd(pfn, flags));
  58        /*
  59         * It's enough to flush this one mapping.
  60         * (PGE mappings get flushed as well)
  61         */
  62        __flush_tlb_one(vaddr);
  63}
  64
  65pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
  66{
  67        pte_t *pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_REPEAT);
  68        if (pte)
  69                clear_page(pte);
  70        return pte;
  71}
  72
  73struct page *pte_alloc_one(struct mm_struct *mm, unsigned long address)
  74{
  75        struct page *pte;
  76
  77#ifdef CONFIG_HIGHPTE
  78        pte = alloc_pages(GFP_KERNEL|__GFP_HIGHMEM|__GFP_REPEAT, 0);
  79#else
  80        pte = alloc_pages(GFP_KERNEL|__GFP_REPEAT, 0);
  81#endif
  82        if (pte)
  83                clear_highpage(pte);
  84        return pte;
  85}
  86
  87/*
  88 * List of all pgd's needed for non-PAE so it can invalidate entries
  89 * in both cached and uncached pgd's; not needed for PAE since the
  90 * kernel pmd is shared. If PAE were not to share the pmd a similar
  91 * tactic would be needed. This is essentially codepath-based locking
  92 * against pageattr.c; it is the unique case in which a valid change
  93 * of kernel pagetables can't be lazily synchronized by vmalloc faults.
  94 * vmalloc faults work because attached pagetables are never freed.
  95 * If the locking proves to be non-performant, a ticketing scheme with
  96 * checks at dup_mmap(), exec(), and other mmlist addition points
  97 * could be used. The locking scheme was chosen on the basis of
  98 * manfred's recommendations and having no core impact whatsoever.
  99 * -- wli
 100 */
 101DEFINE_SPINLOCK(pgd_lock);
 102struct page *pgd_list;
 103
 104static inline void pgd_list_add(pgd_t *pgd)
 105{
 106        struct page *page = virt_to_page(pgd);
 107        page->index = (unsigned long) pgd_list;
 108        if (pgd_list)
 109                set_page_private(pgd_list, (unsigned long) &page->index);
 110        pgd_list = page;
 111        set_page_private(page, (unsigned long) &pgd_list);
 112}
 113
 114static inline void pgd_list_del(pgd_t *pgd)
 115{
 116        struct page *next, **pprev, *page = virt_to_page(pgd);
 117        next = (struct page *) page->index;
 118        pprev = (struct page **) page_private(page);
 119        *pprev = next;
 120        if (next)
 121                set_page_private(next, (unsigned long) pprev);
 122}
 123
 124void pgd_ctor(void *pgd)
 125{
 126        unsigned long flags;
 127
 128        if (PTRS_PER_PMD == 1)
 129                spin_lock_irqsave(&pgd_lock, flags);
 130
 131        memcpy((pgd_t *)pgd + USER_PTRS_PER_PGD,
 132                        swapper_pg_dir + USER_PTRS_PER_PGD,
 133                        (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
 134
 135        if (PTRS_PER_PMD > 1)
 136                return;
 137
 138        pgd_list_add(pgd);
 139        spin_unlock_irqrestore(&pgd_lock, flags);
 140        memset(pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
 141}
 142
 143/* never called when PTRS_PER_PMD > 1 */
 144void pgd_dtor(void *pgd)
 145{
 146        unsigned long flags; /* can be called from interrupt context */
 147
 148        spin_lock_irqsave(&pgd_lock, flags);
 149        pgd_list_del(pgd);
 150        spin_unlock_irqrestore(&pgd_lock, flags);
 151}
 152
 153pgd_t *pgd_alloc(struct mm_struct *mm)
 154{
 155        return quicklist_alloc(0, GFP_KERNEL, pgd_ctor);
 156}
 157
 158void pgd_free(struct mm_struct *mm, pgd_t *pgd)
 159{
 160        quicklist_free(0, pgd_dtor, pgd);
 161}
 162
 163void __init pgtable_cache_init(void)
 164{
 165}
 166
 167void check_pgt_cache(void)
 168{
 169        quicklist_trim(0, pgd_dtor, 25, 16);
 170}
 171