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pgtable.c

/* MN10300 Page table management
 *
 * Copyright (C) 2007 Matsushita Electric Industrial Co., Ltd.
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Modified by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/smp.h>
#include <linux/highmem.h>
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/spinlock.h>
#include <linux/quicklist.h>

#include <asm/system.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>

/*
 * Associate a large virtual page frame with a given physical page frame
 * and protection flags for that frame. pfn is for the base of the page,
 * vaddr is what the page gets mapped to - both must be properly aligned.
 * The pmd must already be instantiated. Assumes PAE mode.
 */
void set_pmd_pfn(unsigned long vaddr, unsigned long pfn, pgprot_t flags)
{
      pgd_t *pgd;
      pud_t *pud;
      pmd_t *pmd;

      if (vaddr & (PMD_SIZE-1)) {         /* vaddr is misaligned */
            printk(KERN_ERR "set_pmd_pfn: vaddr misaligned\n");
            return; /* BUG(); */
      }
      if (pfn & (PTRS_PER_PTE-1)) {       /* pfn is misaligned */
            printk(KERN_ERR "set_pmd_pfn: pfn misaligned\n");
            return; /* BUG(); */
      }
      pgd = swapper_pg_dir + pgd_index(vaddr);
      if (pgd_none(*pgd)) {
            printk(KERN_ERR "set_pmd_pfn: pgd_none\n");
            return; /* BUG(); */
      }
      pud = pud_offset(pgd, vaddr);
      pmd = pmd_offset(pud, vaddr);
      set_pmd(pmd, pfn_pmd(pfn, flags));
      /*
       * It's enough to flush this one mapping.
       * (PGE mappings get flushed as well)
       */
      __flush_tlb_one(vaddr);
}

pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
{
      pte_t *pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_REPEAT);
      if (pte)
            clear_page(pte);
      return pte;
}

struct page *pte_alloc_one(struct mm_struct *mm, unsigned long address)
{
      struct page *pte;

#ifdef CONFIG_HIGHPTE
      pte = alloc_pages(GFP_KERNEL|__GFP_HIGHMEM|__GFP_REPEAT, 0);
#else
      pte = alloc_pages(GFP_KERNEL|__GFP_REPEAT, 0);
#endif
      if (pte)
            clear_highpage(pte);
      return pte;
}

/*
 * List of all pgd's needed for non-PAE so it can invalidate entries
 * in both cached and uncached pgd's; not needed for PAE since the
 * kernel pmd is shared. If PAE were not to share the pmd a similar
 * tactic would be needed. This is essentially codepath-based locking
 * against pageattr.c; it is the unique case in which a valid change
 * of kernel pagetables can't be lazily synchronized by vmalloc faults.
 * vmalloc faults work because attached pagetables are never freed.
 * If the locking proves to be non-performant, a ticketing scheme with
 * checks at dup_mmap(), exec(), and other mmlist addition points
 * could be used. The locking scheme was chosen on the basis of
 * manfred's recommendations and having no core impact whatsoever.
 * -- wli
 */
DEFINE_SPINLOCK(pgd_lock);
struct page *pgd_list;

static inline void pgd_list_add(pgd_t *pgd)
{
      struct page *page = virt_to_page(pgd);
      page->index = (unsigned long) pgd_list;
      if (pgd_list)
            set_page_private(pgd_list, (unsigned long) &page->index);
      pgd_list = page;
      set_page_private(page, (unsigned long) &pgd_list);
}

static inline void pgd_list_del(pgd_t *pgd)
{
      struct page *next, **pprev, *page = virt_to_page(pgd);
      next = (struct page *) page->index;
      pprev = (struct page **) page_private(page);
      *pprev = next;
      if (next)
            set_page_private(next, (unsigned long) pprev);
}

void pgd_ctor(void *pgd)
{
      unsigned long flags;

      if (PTRS_PER_PMD == 1)
            spin_lock_irqsave(&pgd_lock, flags);

      memcpy((pgd_t *)pgd + USER_PTRS_PER_PGD,
                  swapper_pg_dir + USER_PTRS_PER_PGD,
                  (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));

      if (PTRS_PER_PMD > 1)
            return;

      pgd_list_add(pgd);
      spin_unlock_irqrestore(&pgd_lock, flags);
      memset(pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
}

/* never called when PTRS_PER_PMD > 1 */
void pgd_dtor(void *pgd)
{
      unsigned long flags; /* can be called from interrupt context */

      spin_lock_irqsave(&pgd_lock, flags);
      pgd_list_del(pgd);
      spin_unlock_irqrestore(&pgd_lock, flags);
}

pgd_t *pgd_alloc(struct mm_struct *mm)
{
      return quicklist_alloc(0, GFP_KERNEL, pgd_ctor);
}

void pgd_free(struct mm_struct *mm, pgd_t *pgd)
{
      quicklist_free(0, pgd_dtor, pgd);
}

void __init pgtable_cache_init(void)
{
}

void check_pgt_cache(void)
{
      quicklist_trim(0, pgd_dtor, 25, 16);
}

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