LXR linux/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
  21pgd_t swapper_pg_dir[PTRS_PER_PGD] __attribute__((aligned(PAGE_SIZE)));
  22
  23pte_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
  31pgtable_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
  48void __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 */
  82DEFINE_SPINLOCK(pgd_lock);
  83struct page *pgd_list;
  84
  85static 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
  95static 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
 105void 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 */
 125void 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
 134pgd_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
 145void 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
 151void __init pgtable_cache_init(void)
 152{
 153}
 154
 155void check_pgt_cache(void)
 156{
 157        quicklist_trim(0, pgd_dtor, 25, 16);
 158}
 159
 160