LXR linux/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 */
  35void 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
  64pte_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
  72struct 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 */
 105DEFINE_SPINLOCK(pgd_lock);
 106struct page *pgd_list;
 107
 108static 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
 118static 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
 128void 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 */
 148void 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
 157pgd_t *pgd_alloc(struct mm_struct *mm)
 158{
 159        return quicklist_alloc(0, GFP_KERNEL, pgd_ctor);
 160}
 161
 162void pgd_free(struct mm_struct *mm, pgd_t *pgd)
 163{
 164        quicklist_free(0, pgd_dtor, pgd);
 165}
 166
 167void __init pgtable_cache_init(void)
 168{
 169}
 170
 171void check_pgt_cache(void)
 172{
 173        quicklist_trim(0, pgd_dtor, 25, 16);
 174}
 175