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/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  */
  36 void 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
  65 pte_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
  73 struct 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  */
 101 DEFINE_SPINLOCK(pgd_lock);
 102 struct page *pgd_list;
 103
 104 static 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
 114 static 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
 124 void 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 */
 144 void 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
 153 pgd_t *pgd_alloc(struct mm_struct *mm)
 154 {
 155         return quicklist_alloc(0, GFP_KERNEL, pgd_ctor);
 156 }
 157
 158 void pgd_free(struct mm_struct *mm, pgd_t *pgd)
 159 {
 160         quicklist_free(0, pgd_dtor, pgd);
 161 }
 162
 163 void __init pgtable_cache_init(void)
 164 {
 165 }
 166
 167 void check_pgt_cache(void)
 168 {
 169         quicklist_trim(0, pgd_dtor, 25, 16);
 170 }