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/slab.h>
  14 #include <linux/mm.h>
  15 #include <linux/highmem.h>
  16 #include <asm/pgalloc.h>
  17 #include <asm/page.h>
  18 #include <asm/cacheflush.h>
  19
  20 pgd_t swapper_pg_dir[PTRS_PER_PGD] __attribute__((aligned(PAGE_SIZE)));
  21 struct kmem_cache *pgd_cache;
  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 struct page *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         flush_dcache_page(page);
  43         return page;
  44 }
  45
  46 void __set_pmd(pmd_t *pmdptr, unsigned long pmd)
  47 {
  48         unsigned long *__ste_p = pmdptr->ste;
  49         int loop;
  50
  51         if (!pmd) {
  52                 memset(__ste_p, 0, PME_SIZE);
  53         }
  54         else {
  55                 BUG_ON(pmd & (0x3f00 | xAMPRx_SS | 0xe));
  56
  57                 for (loop = PME_SIZE; loop > 0; loop -= 4) {
  58                         *__ste_p++ = pmd;
  59                         pmd += __frv_PT_SIZE;
  60                 }
  61         }
  62
  63         frv_dcache_writeback((unsigned long) pmdptr, (unsigned long) (pmdptr + 1));
  64 }
  65
  66 /*
  67  * List of all pgd's needed for non-PAE so it can invalidate entries
  68  * in both cached and uncached pgd's; not needed for PAE since the
  69  * kernel pmd is shared. If PAE were not to share the pmd a similar
  70  * tactic would be needed. This is essentially codepath-based locking
  71  * against pageattr.c; it is the unique case in which a valid change
  72  * of kernel pagetables can't be lazily synchronized by vmalloc faults.
  73  * vmalloc faults work because attached pagetables are never freed.
  74  * If the locking proves to be non-performant, a ticketing scheme with
  75  * checks at dup_mmap(), exec(), and other mmlist addition points
  76  * could be used. The locking scheme was chosen on the basis of
  77  * manfred's recommendations and having no core impact whatsoever.
  78  * -- wli
  79  */
  80 DEFINE_SPINLOCK(pgd_lock);
  81 struct page *pgd_list;
  82
  83 static inline void pgd_list_add(pgd_t *pgd)
  84 {
  85         struct page *page = virt_to_page(pgd);
  86         page->index = (unsigned long) pgd_list;
  87         if (pgd_list)
  88                 set_page_private(pgd_list, (unsigned long) &page->index);
  89         pgd_list = page;
  90         set_page_private(page, (unsigned long)&pgd_list);
  91 }
  92
  93 static inline void pgd_list_del(pgd_t *pgd)
  94 {
  95         struct page *next, **pprev, *page = virt_to_page(pgd);
  96         next = (struct page *) page->index;
  97         pprev = (struct page **) page_private(page);
  98         *pprev = next;
  99         if (next)
 100                 set_page_private(next, (unsigned long) pprev);
 101 }
 102
 103 void pgd_ctor(void *pgd, struct kmem_cache *cache, unsigned long unused)
 104 {
 105         unsigned long flags;
 106
 107         if (PTRS_PER_PMD == 1)
 108                 spin_lock_irqsave(&pgd_lock, flags);
 109
 110         memcpy((pgd_t *) pgd + USER_PGDS_IN_LAST_PML4,
 111                swapper_pg_dir + USER_PGDS_IN_LAST_PML4,
 112                (PTRS_PER_PGD - USER_PGDS_IN_LAST_PML4) * sizeof(pgd_t));
 113
 114         if (PTRS_PER_PMD > 1)
 115                 return;
 116
 117         pgd_list_add(pgd);
 118         spin_unlock_irqrestore(&pgd_lock, flags);
 119         memset(pgd, 0, USER_PGDS_IN_LAST_PML4 * sizeof(pgd_t));
 120 }
 121
 122 /* never called when PTRS_PER_PMD > 1 */
 123 void pgd_dtor(void *pgd, struct kmem_cache *cache, unsigned long unused)
 124 {
 125         unsigned long flags; /* can be called from interrupt context */
 126
 127         spin_lock_irqsave(&pgd_lock, flags);
 128         pgd_list_del(pgd);
 129         spin_unlock_irqrestore(&pgd_lock, flags);
 130 }
 131
 132 pgd_t *pgd_alloc(struct mm_struct *mm)
 133 {
 134         pgd_t *pgd;
 135
 136         pgd = kmem_cache_alloc(pgd_cache, GFP_KERNEL);
 137         if (!pgd)
 138                 return pgd;
 139
 140         return pgd;
 141 }
 142
 143 void pgd_free(pgd_t *pgd)
 144 {
 145         /* in the non-PAE case, clear_page_tables() clears user pgd entries */
 146         kmem_cache_free(pgd_cache, pgd);
 147 }
 148
 149 void __init pgtable_cache_init(void)
 150 {
 151         pgd_cache = kmem_cache_create("pgd",
 152                                       PTRS_PER_PGD * sizeof(pgd_t),
 153                                       PTRS_PER_PGD * sizeof(pgd_t),
 154                                       SLAB_PANIC,
 155                                       pgd_ctor,
 156                                       pgd_dtor);
 157 }