pgtable.c revision 4984d2d88805609e7702e8ee72b5e148c992ae7b 
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/mm.h>
16#include <linux/swap.h>
17#include <linux/smp.h>
18#include <linux/highmem.h>
19#include <linux/slab.h>
20#include <linux/pagemap.h>
21#include <linux/spinlock.h>
22#include <linux/quicklist.h>
23
24#include <asm/system.h>
25#include <asm/pgtable.h>
26#include <asm/pgalloc.h>
27#include <asm/tlb.h>
28#include <asm/tlbflush.h>
29
30/*
31 * Associate a large virtual page frame with a given physical page frame
32 * and protection flags for that frame. pfn is for the base of the page,
33 * vaddr is what the page gets mapped to - both must be properly aligned.
34 * The pmd must already be instantiated. Assumes PAE mode.
35 */
36void set_pmd_pfn(unsigned long vaddr, unsigned long pfn, pgprot_t flags)
37{
38	pgd_t *pgd;
39	pud_t *pud;
40	pmd_t *pmd;
41
42	if (vaddr & (PMD_SIZE-1)) {		/* vaddr is misaligned */
43		printk(KERN_ERR "set_pmd_pfn: vaddr misaligned\n");
44		return; /* BUG(); */
45	}
46	if (pfn & (PTRS_PER_PTE-1)) {		/* pfn is misaligned */
47		printk(KERN_ERR "set_pmd_pfn: pfn misaligned\n");
48		return; /* BUG(); */
49	}
50	pgd = swapper_pg_dir + pgd_index(vaddr);
51	if (pgd_none(*pgd)) {
52		printk(KERN_ERR "set_pmd_pfn: pgd_none\n");
53		return; /* BUG(); */
54	}
55	pud = pud_offset(pgd, vaddr);
56	pmd = pmd_offset(pud, vaddr);
57	set_pmd(pmd, pfn_pmd(pfn, flags));
58	/*
59	 * It's enough to flush this one mapping.
60	 * (PGE mappings get flushed as well)
61	 */
62	__flush_tlb_one(vaddr);
63}
64
65pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
66{
67	pte_t *pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_REPEAT);
68	if (pte)
69		clear_page(pte);
70	return pte;
71}
72
73struct page *pte_alloc_one(struct mm_struct *mm, unsigned long address)
74{
75	struct page *pte;
76
77#ifdef CONFIG_HIGHPTE
78	pte = alloc_pages(GFP_KERNEL|__GFP_HIGHMEM|__GFP_REPEAT, 0);
79#else
80	pte = alloc_pages(GFP_KERNEL|__GFP_REPEAT, 0);
81#endif
82	if (pte)
83		clear_highpage(pte);
84	return pte;
85}
86
87/*
88 * List of all pgd's needed for non-PAE so it can invalidate entries
89 * in both cached and uncached pgd's; not needed for PAE since the
90 * kernel pmd is shared. If PAE were not to share the pmd a similar
91 * tactic would be needed. This is essentially codepath-based locking
92 * against pageattr.c; it is the unique case in which a valid change
93 * of kernel pagetables can't be lazily synchronized by vmalloc faults.
94 * vmalloc faults work because attached pagetables are never freed.
95 * If the locking proves to be non-performant, a ticketing scheme with
96 * checks at dup_mmap(), exec(), and other mmlist addition points
97 * could be used. The locking scheme was chosen on the basis of
98 * manfred's recommendations and having no core impact whatsoever.
99 * -- wli
100 */
101DEFINE_SPINLOCK(pgd_lock);
102struct page *pgd_list;
103
104static inline void pgd_list_add(pgd_t *pgd)
105{
106	struct page *page = virt_to_page(pgd);
107	page->index = (unsigned long) pgd_list;
108	if (pgd_list)
109		set_page_private(pgd_list, (unsigned long) &page->index);
110	pgd_list = page;
111	set_page_private(page, (unsigned long) &pgd_list);
112}
113
114static inline void pgd_list_del(pgd_t *pgd)
115{
116	struct page *next, **pprev, *page = virt_to_page(pgd);
117	next = (struct page *) page->index;
118	pprev = (struct page **) page_private(page);
119	*pprev = next;
120	if (next)
121		set_page_private(next, (unsigned long) pprev);
122}
123
124void pgd_ctor(void *pgd)
125{
126	unsigned long flags;
127
128	if (PTRS_PER_PMD == 1)
129		spin_lock_irqsave(&pgd_lock, flags);
130
131	memcpy((pgd_t *)pgd + USER_PTRS_PER_PGD,
132			swapper_pg_dir + USER_PTRS_PER_PGD,
133			(PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
134
135	if (PTRS_PER_PMD > 1)
136		return;
137
138	pgd_list_add(pgd);
139	spin_unlock_irqrestore(&pgd_lock, flags);
140	memset(pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
141}
142
143/* never called when PTRS_PER_PMD > 1 */
144void pgd_dtor(void *pgd)
145{
146	unsigned long flags; /* can be called from interrupt context */
147
148	spin_lock_irqsave(&pgd_lock, flags);
149	pgd_list_del(pgd);
150	spin_unlock_irqrestore(&pgd_lock, flags);
151}
152
153pgd_t *pgd_alloc(struct mm_struct *mm)
154{
155	return quicklist_alloc(0, GFP_KERNEL, pgd_ctor);
156}
157
158void pgd_free(struct mm_struct *mm, pgd_t *pgd)
159{
160	quicklist_free(0, pgd_dtor, pgd);
161}
162
163void __init pgtable_cache_init(void)
164{
165}
166
167void check_pgt_cache(void)
168{
169	quicklist_trim(0, pgd_dtor, 25, 16);
170}
171