/* 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/gfp.h>
  #include <linux/mm.h>
  #include <linux/swap.h>
  #include <linux/smp.h>
  #include <linux/highmem.h>
  #include <linux/pagemap.h>
  #include <linux/spinlock.h>
  #include <linux/quicklist.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
  ");
  		return; /* BUG(); */
  	}
  	if (pfn & (PTRS_PER_PTE-1)) {		/* pfn is misaligned */
  		printk(KERN_ERR "set_pmd_pfn: pfn misaligned
  ");
  		return; /* BUG(); */
  	}
  	pgd = swapper_pg_dir + pgd_index(vaddr);
  	if (pgd_none(*pgd)) {
  		printk(KERN_ERR "set_pmd_pfn: pgd_none
  ");
  		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)
  	 */
  	local_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)
  		return NULL;
  	clear_highpage(pte);
  	if (!pgtable_page_ctor(pte)) {
  		__free_page(pte);
  		return NULL;
  	}
  	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.
   * -- nyc
   */
  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);
  }