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);
  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, 0);
  37 #else
  38         page = alloc_pages(GFP_KERNEL, 0);
  39 #endif
  40         if (!page)
  41                 return NULL;
  42
  43         clear_highpage(page);
  44         if (!pgtable_page_ctor(page)) {
  45                 __free_page(page);
  46                 return NULL;
  47         }
  48         flush_dcache_page(page);
  49         return page;
  50 }
  51
  52 void __set_pmd(pmd_t *pmdptr, unsigned long pmd)
  53 {
  54         unsigned long *__ste_p = pmdptr->ste;
  55         int loop;
  56
  57         if (!pmd) {
  58                 memset(__ste_p, 0, PME_SIZE);
  59         }
  60         else {
  61                 BUG_ON(pmd & (0x3f00 | xAMPRx_SS | 0xe));
  62
  63                 for (loop = PME_SIZE; loop > 0; loop -= 4) {
  64                         *__ste_p++ = pmd;
  65                         pmd += __frv_PT_SIZE;
  66                 }
  67         }
  68
  69         frv_dcache_writeback((unsigned long) pmdptr, (unsigned long) (pmdptr + 1));
  70 }
  71
  72 /*
  73  * List of all pgd's needed for non-PAE so it can invalidate entries
  74  * in both cached and uncached pgd's; not needed for PAE since the
  75  * kernel pmd is shared. If PAE were not to share the pmd a similar
  76  * tactic would be needed. This is essentially codepath-based locking
  77  * against pageattr.c; it is the unique case in which a valid change
  78  * of kernel pagetables can't be lazily synchronized by vmalloc faults.
  79  * vmalloc faults work because attached pagetables are never freed.
  80  * If the locking proves to be non-performant, a ticketing scheme with
  81  * checks at dup_mmap(), exec(), and other mmlist addition points
  82  * could be used. The locking scheme was chosen on the basis of
  83  * manfred's recommendations and having no core impact whatsoever.
  84  * -- nyc
  85  */
  86 DEFINE_SPINLOCK(pgd_lock);
  87 struct page *pgd_list;
  88
  89 static inline void pgd_list_add(pgd_t *pgd)
  90 {
  91         struct page *page = virt_to_page(pgd);
  92         page->index = (unsigned long) pgd_list;
  93         if (pgd_list)
  94                 set_page_private(pgd_list, (unsigned long) &page->index);
  95         pgd_list = page;
  96         set_page_private(page, (unsigned long)&pgd_list);
  97 }
  98
  99 static inline void pgd_list_del(pgd_t *pgd)
 100 {
 101         struct page *next, **pprev, *page = virt_to_page(pgd);
 102         next = (struct page *) page->index;
 103         pprev = (struct page **) page_private(page);
 104         *pprev = next;
 105         if (next)
 106                 set_page_private(next, (unsigned long) pprev);
 107 }
 108
 109 void pgd_ctor(void *pgd)
 110 {
 111         unsigned long flags;
 112
 113         if (PTRS_PER_PMD == 1)
 114                 spin_lock_irqsave(&pgd_lock, flags);
 115
 116         memcpy((pgd_t *) pgd + USER_PGDS_IN_LAST_PML4,
 117                swapper_pg_dir + USER_PGDS_IN_LAST_PML4,
 118                (PTRS_PER_PGD - USER_PGDS_IN_LAST_PML4) * sizeof(pgd_t));
 119
 120         if (PTRS_PER_PMD > 1)
 121                 return;
 122
 123         pgd_list_add(pgd);
 124         spin_unlock_irqrestore(&pgd_lock, flags);
 125         memset(pgd, 0, USER_PGDS_IN_LAST_PML4 * sizeof(pgd_t));
 126 }
 127
 128 /* never called when PTRS_PER_PMD > 1 */
 129 void pgd_dtor(void *pgd)
 130 {
 131         unsigned long flags; /* can be called from interrupt context */
 132
 133         spin_lock_irqsave(&pgd_lock, flags);
 134         pgd_list_del(pgd);
 135         spin_unlock_irqrestore(&pgd_lock, flags);
 136 }
 137
 138 pgd_t *pgd_alloc(struct mm_struct *mm)
 139 {
 140         return quicklist_alloc(0, GFP_KERNEL, pgd_ctor);
 141 }
 142
 143 void pgd_free(struct mm_struct *mm, pgd_t *pgd)
 144 {
 145         /* in the non-PAE case, clear_page_tables() clears user pgd entries */
 146         quicklist_free(0, pgd_dtor, pgd);
 147 }
 148
 149 void __init pgtable_cache_init(void)
 150 {
 151 }
 152
 153 void check_pgt_cache(void)
 154 {
 155         quicklist_trim(0, pgd_dtor, 25, 16);
 156 }
 157