1/* MN10300 Page table management
  2 *
  3 * Copyright (C) 2007 Matsushita Electric Industrial Co., Ltd.
  4 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
  5 * Modified by David Howells (dhowells@redhat.com)
  6 *
  7 * This program is free software; you can redistribute it and/or
  8 * modify it under the terms of the GNU General Public Licence
  9 * as published by the Free Software Foundation; either version
 10 * 2 of the Licence, or (at your option) any later version.
 11 */
 12#include <linux/sched.h>
 13#include <linux/kernel.h>
 14#include <linux/errno.h>
 15#include <linux/gfp.h>
 16#include <linux/mm.h>
 17#include <linux/swap.h>
 18#include <linux/smp.h>
 19#include <linux/highmem.h>
 20#include <linux/pagemap.h>
 21#include <linux/spinlock.h>
 22#include <linux/quicklist.h>
 23
 24#include <asm/pgtable.h>
 25#include <asm/pgalloc.h>
 26#include <asm/tlb.h>
 27#include <asm/tlbflush.h>
 28
 29/*
 30 * Associate a large virtual page frame with a given physical page frame
 31 * and protection flags for that frame. pfn is for the base of the page,
 32 * vaddr is what the page gets mapped to - both must be properly aligned.
 33 * The pmd must already be instantiated. Assumes PAE mode.
 34 */
 35void set_pmd_pfn(unsigned long vaddr, unsigned long pfn, pgprot_t flags)
 36{
 37	pgd_t *pgd;
 38	pud_t *pud;
 39	pmd_t *pmd;
 40
 41	if (vaddr & (PMD_SIZE-1)) {		/* vaddr is misaligned */
 42		printk(KERN_ERR "set_pmd_pfn: vaddr misaligned\n");
 43		return; /* BUG(); */
 44	}
 45	if (pfn & (PTRS_PER_PTE-1)) {		/* pfn is misaligned */
 46		printk(KERN_ERR "set_pmd_pfn: pfn misaligned\n");
 47		return; /* BUG(); */
 48	}
 49	pgd = swapper_pg_dir + pgd_index(vaddr);
 50	if (pgd_none(*pgd)) {
 51		printk(KERN_ERR "set_pmd_pfn: pgd_none\n");
 52		return; /* BUG(); */
 53	}
 54	pud = pud_offset(pgd, vaddr);
 55	pmd = pmd_offset(pud, vaddr);
 56	set_pmd(pmd, pfn_pmd(pfn, flags));
 57	/*
 58	 * It's enough to flush this one mapping.
 59	 * (PGE mappings get flushed as well)
 60	 */
 61	local_flush_tlb_one(vaddr);
 62}
 63
 64pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
 65{
 66	pte_t *pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_REPEAT);
 67	if (pte)
 68		clear_page(pte);
 69	return pte;
 70}
 71
 72struct page *pte_alloc_one(struct mm_struct *mm, unsigned long address)
 73{
 74	struct page *pte;
 75
 76#ifdef CONFIG_HIGHPTE
 77	pte = alloc_pages(GFP_KERNEL|__GFP_HIGHMEM|__GFP_REPEAT, 0);
 78#else
 79	pte = alloc_pages(GFP_KERNEL|__GFP_REPEAT, 0);
 80#endif
 81	if (pte)
 82		clear_highpage(pte);
 83	return pte;
 84}
 85
 86/*
 87 * List of all pgd's needed for non-PAE so it can invalidate entries
 88 * in both cached and uncached pgd's; not needed for PAE since the
 89 * kernel pmd is shared. If PAE were not to share the pmd a similar
 90 * tactic would be needed. This is essentially codepath-based locking
 91 * against pageattr.c; it is the unique case in which a valid change
 92 * of kernel pagetables can't be lazily synchronized by vmalloc faults.
 93 * vmalloc faults work because attached pagetables are never freed.
 94 * If the locking proves to be non-performant, a ticketing scheme with
 95 * checks at dup_mmap(), exec(), and other mmlist addition points
 96 * could be used. The locking scheme was chosen on the basis of
 97 * manfred's recommendations and having no core impact whatsoever.
 98 * -- wli
 99 */
100DEFINE_SPINLOCK(pgd_lock);
101struct page *pgd_list;
102
103static inline void pgd_list_add(pgd_t *pgd)
104{
105	struct page *page = virt_to_page(pgd);
106	page->index = (unsigned long) pgd_list;
107	if (pgd_list)
108		set_page_private(pgd_list, (unsigned long) &page->index);
109	pgd_list = page;
110	set_page_private(page, (unsigned long) &pgd_list);
111}
112
113static inline void pgd_list_del(pgd_t *pgd)
114{
115	struct page *next, **pprev, *page = virt_to_page(pgd);
116	next = (struct page *) page->index;
117	pprev = (struct page **) page_private(page);
118	*pprev = next;
119	if (next)
120		set_page_private(next, (unsigned long) pprev);
121}
122
123void pgd_ctor(void *pgd)
124{
125	unsigned long flags;
126
127	if (PTRS_PER_PMD == 1)
128		spin_lock_irqsave(&pgd_lock, flags);
129
130	memcpy((pgd_t *)pgd + USER_PTRS_PER_PGD,
131			swapper_pg_dir + USER_PTRS_PER_PGD,
132			(PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
133
134	if (PTRS_PER_PMD > 1)
135		return;
136
137	pgd_list_add(pgd);
138	spin_unlock_irqrestore(&pgd_lock, flags);
139	memset(pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
140}
141
142/* never called when PTRS_PER_PMD > 1 */
143void pgd_dtor(void *pgd)
144{
145	unsigned long flags; /* can be called from interrupt context */
146
147	spin_lock_irqsave(&pgd_lock, flags);
148	pgd_list_del(pgd);
149	spin_unlock_irqrestore(&pgd_lock, flags);
150}
151
152pgd_t *pgd_alloc(struct mm_struct *mm)
153{
154	return quicklist_alloc(0, GFP_KERNEL, pgd_ctor);
155}
156
157void pgd_free(struct mm_struct *mm, pgd_t *pgd)
158{
159	quicklist_free(0, pgd_dtor, pgd);
160}
161
162void __init pgtable_cache_init(void)
163{
164}
165
166void check_pgt_cache(void)
167{
168	quicklist_trim(0, pgd_dtor, 25, 16);
169}