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		return NULL;
83	clear_highpage(pte);
84	if (!pgtable_page_ctor(pte)) {
85		__free_page(pte);
86		return NULL;
87	}
88	return pte;
89}
90
91/*
92 * List of all pgd's needed for non-PAE so it can invalidate entries
93 * in both cached and uncached pgd's; not needed for PAE since the
94 * kernel pmd is shared. If PAE were not to share the pmd a similar
95 * tactic would be needed. This is essentially codepath-based locking
96 * against pageattr.c; it is the unique case in which a valid change
97 * of kernel pagetables can't be lazily synchronized by vmalloc faults.
98 * vmalloc faults work because attached pagetables are never freed.
99 * If the locking proves to be non-performant, a ticketing scheme with
100 * checks at dup_mmap(), exec(), and other mmlist addition points
101 * could be used. The locking scheme was chosen on the basis of
102 * manfred's recommendations and having no core impact whatsoever.
103 * -- nyc
104 */
105DEFINE_SPINLOCK(pgd_lock);
106struct page *pgd_list;
107
108static inline void pgd_list_add(pgd_t *pgd)
109{
110	struct page *page = virt_to_page(pgd);
111	page->index = (unsigned long) pgd_list;
112	if (pgd_list)
113		set_page_private(pgd_list, (unsigned long) &page->index);
114	pgd_list = page;
115	set_page_private(page, (unsigned long) &pgd_list);
116}
117
118static inline void pgd_list_del(pgd_t *pgd)
119{
120	struct page *next, **pprev, *page = virt_to_page(pgd);
121	next = (struct page *) page->index;
122	pprev = (struct page **) page_private(page);
123	*pprev = next;
124	if (next)
125		set_page_private(next, (unsigned long) pprev);
126}
127
128void pgd_ctor(void *pgd)
129{
130	unsigned long flags;
131
132	if (PTRS_PER_PMD == 1)
133		spin_lock_irqsave(&pgd_lock, flags);
134
135	memcpy((pgd_t *)pgd + USER_PTRS_PER_PGD,
136			swapper_pg_dir + USER_PTRS_PER_PGD,
137			(PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
138
139	if (PTRS_PER_PMD > 1)
140		return;
141
142	pgd_list_add(pgd);
143	spin_unlock_irqrestore(&pgd_lock, flags);
144	memset(pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
145}
146
147/* never called when PTRS_PER_PMD > 1 */
148void pgd_dtor(void *pgd)
149{
150	unsigned long flags; /* can be called from interrupt context */
151
152	spin_lock_irqsave(&pgd_lock, flags);
153	pgd_list_del(pgd);
154	spin_unlock_irqrestore(&pgd_lock, flags);
155}
156
157pgd_t *pgd_alloc(struct mm_struct *mm)
158{
159	return quicklist_alloc(0, GFP_KERNEL, pgd_ctor);
160}
161
162void pgd_free(struct mm_struct *mm, pgd_t *pgd)
163{
164	quicklist_free(0, pgd_dtor, pgd);
165}
166
167void __init pgtable_cache_init(void)
168{
169}
170
171void check_pgt_cache(void)
172{
173	quicklist_trim(0, pgd_dtor, 25, 16);
174}
175