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);
  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, 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
  52void __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 */
  86DEFINE_SPINLOCK(pgd_lock);
  87struct page *pgd_list;
  88
  89static 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
  99static 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
 109void 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 */
 129void 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
 138pgd_t *pgd_alloc(struct mm_struct *mm)
 139{
 140        return quicklist_alloc(0, GFP_KERNEL, pgd_ctor);
 141}
 142
 143void 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
 149void __init pgtable_cache_init(void)
 150{
 151}
 152
 153void check_pgt_cache(void)
 154{
 155        quicklist_trim(0, pgd_dtor, 25, 16);
 156}
 157
 158