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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  */
set_pmd_pfn(unsigned long vaddr,unsigned long pfn,pgprot_t flags)36 void 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 
pte_alloc_one_kernel(struct mm_struct * mm,unsigned long address)65 pte_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 
pte_alloc_one(struct mm_struct * mm,unsigned long address)73 struct 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  */
101 DEFINE_SPINLOCK(pgd_lock);
102 struct page *pgd_list;
103 
pgd_list_add(pgd_t * pgd)104 static 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 
pgd_list_del(pgd_t * pgd)114 static 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 
pgd_ctor(void * pgd)124 void 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 */
pgd_dtor(void * pgd)144 void 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 
pgd_alloc(struct mm_struct * mm)153 pgd_t *pgd_alloc(struct mm_struct *mm)
154 {
155 	return quicklist_alloc(0, GFP_KERNEL, pgd_ctor);
156 }
157 
pgd_free(struct mm_struct * mm,pgd_t * pgd)158 void pgd_free(struct mm_struct *mm, pgd_t *pgd)
159 {
160 	quicklist_free(0, pgd_dtor, pgd);
161 }
162 
pgtable_cache_init(void)163 void __init pgtable_cache_init(void)
164 {
165 }
166 
check_pgt_cache(void)167 void check_pgt_cache(void)
168 {
169 	quicklist_trim(0, pgd_dtor, 25, 16);
170 }
171