release/src-rt-6.x.4708/linux/linux-2.6.36/arch/frv/mm/pgalloc.c

   1 /* pgalloc.c: page directory & page table allocation
   2  *
   3  * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   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 #include <linux/sched.h>
  13 #include <linux/gfp.h>
  14 #include <linux/mm.h>
  15 #include <linux/highmem.h>
  16 #include <linux/quicklist.h>
  17 #include <asm/pgalloc.h>
  18 #include <asm/page.h>
  19 #include <asm/cacheflush.h>
  20
  21 pgd_t swapper_pg_dir[PTRS_PER_PGD] __attribute__((aligned(PAGE_SIZE)));
  22
  23 pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
  24 {
  25         pte_t *pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_REPEAT);
  26         if (pte)
  27                 clear_page(pte);
  28         return pte;
  29 }
  30
  31 pgtable_t pte_alloc_one(struct mm_struct *mm, unsigned long address)
  32 {
  33         struct page *page;
  34
  35 #ifdef CONFIG_HIGHPTE
  36         page = alloc_pages(GFP_KERNEL|__GFP_HIGHMEM|__GFP_REPEAT, 0);
  37 #else
  38         page = alloc_pages(GFP_KERNEL|__GFP_REPEAT, 0);
  39 #endif
  40         if (page) {
  41                 clear_highpage(page);
  42                 pgtable_page_ctor(page);
  43                 flush_dcache_page(page);
  44         }
  45         return page;
  46 }
  47
  48 void __set_pmd(pmd_t *pmdptr, unsigned long pmd)
  49 {
  50         unsigned long *__ste_p = pmdptr->ste;
  51         int loop;
  52
  53         if (!pmd) {
  54                 memset(__ste_p, 0, PME_SIZE);
  55         }
  56         else {
  57                 BUG_ON(pmd & (0x3f00 | xAMPRx_SS | 0xe));
  58
  59                 for (loop = PME_SIZE; loop > 0; loop -= 4) {
  60                         *__ste_p++ = pmd;
  61                         pmd += __frv_PT_SIZE;
  62                 }
  63         }
  64
  65         frv_dcache_writeback((unsigned long) pmdptr, (unsigned long) (pmdptr + 1));
  66 }
  67
  68 /*
  69  * List of all pgd's needed for non-PAE so it can invalidate entries
  70  * in both cached and uncached pgd's; not needed for PAE since the
  71  * kernel pmd is shared. If PAE were not to share the pmd a similar
  72  * tactic would be needed. This is essentially codepath-based locking
  73  * against pageattr.c; it is the unique case in which a valid change
  74  * of kernel pagetables can't be lazily synchronized by vmalloc faults.
  75  * vmalloc faults work because attached pagetables are never freed.
  76  * If the locking proves to be non-performant, a ticketing scheme with
  77  * checks at dup_mmap(), exec(), and other mmlist addition points
  78  * could be used. The locking scheme was chosen on the basis of
  79  * manfred's recommendations and having no core impact whatsoever.
  80  * -- wli
  81  */
  82 DEFINE_SPINLOCK(pgd_lock);
  83 struct page *pgd_list;
  84
  85 static inline void pgd_list_add(pgd_t *pgd)
  86 {
  87         struct page *page = virt_to_page(pgd);
  88         page->index = (unsigned long) pgd_list;
  89         if (pgd_list)
  90                 set_page_private(pgd_list, (unsigned long) &page->index);
  91         pgd_list = page;
  92         set_page_private(page, (unsigned long)&pgd_list);
  93 }
  94
  95 static inline void pgd_list_del(pgd_t *pgd)
  96 {
  97         struct page *next, **pprev, *page = virt_to_page(pgd);
  98         next = (struct page *) page->index;
  99         pprev = (struct page **) page_private(page);
 100         *pprev = next;
 101         if (next)
 102                 set_page_private(next, (unsigned long) pprev);
 103 }
 104
 105 void pgd_ctor(void *pgd)
 106 {
 107         unsigned long flags;
 108
 109         if (PTRS_PER_PMD == 1)
 110                 spin_lock_irqsave(&pgd_lock, flags);
 111
 112         memcpy((pgd_t *) pgd + USER_PGDS_IN_LAST_PML4,
 113                swapper_pg_dir + USER_PGDS_IN_LAST_PML4,
 114                (PTRS_PER_PGD - USER_PGDS_IN_LAST_PML4) * sizeof(pgd_t));
 115
 116         if (PTRS_PER_PMD > 1)
 117                 return;
 118
 119         pgd_list_add(pgd);
 120         spin_unlock_irqrestore(&pgd_lock, flags);
 121         memset(pgd, 0, USER_PGDS_IN_LAST_PML4 * sizeof(pgd_t));
 122 }
 123
 124 /* never called when PTRS_PER_PMD > 1 */
 125 void pgd_dtor(void *pgd)
 126 {
 127         unsigned long flags; /* can be called from interrupt context */
 128
 129         spin_lock_irqsave(&pgd_lock, flags);
 130         pgd_list_del(pgd);
 131         spin_unlock_irqrestore(&pgd_lock, flags);
 132 }
 133
 134 pgd_t *pgd_alloc(struct mm_struct *mm)
 135 {
 136         pgd_t *pgd;
 137
 138         pgd = quicklist_alloc(0, GFP_KERNEL, pgd_ctor);
 139         if (!pgd)
 140                 return pgd;
 141
 142         return pgd;
 143 }
 144
 145 void pgd_free(struct mm_struct *mm, pgd_t *pgd)
 146 {
 147         /* in the non-PAE case, clear_page_tables() clears user pgd entries */
 148         quicklist_free(0, pgd_dtor, pgd);
 149 }
 150
 151 void __init pgtable_cache_init(void)
 152 {
 153 }
 154
 155 void check_pgt_cache(void)
 156 {
 157         quicklist_trim(0, pgd_dtor, 25, 16);
 158 }