1/* pgalloc.c: page directory & page table allocation
2 *
3 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12#include <linux/sched.h>
13#include <linux/slab.h>
14#include <linux/mm.h>
15#include <linux/highmem.h>
16#include <linux/quicklist.h>
17#include <asm/pgalloc.h>
18#include <asm/page.h>
19#include <asm/cacheflush.h>
20
21pgd_t swapper_pg_dir[PTRS_PER_PGD] __attribute__((aligned(PAGE_SIZE)));
22
23pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
24{
25	pte_t *pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_REPEAT);
26	if (pte)
27		clear_page(pte);
28	return pte;
29}
30
31struct page *pte_alloc_one(struct mm_struct *mm, unsigned long address)
32{
33	struct page *page;
34
35#ifdef CONFIG_HIGHPTE
36	page = alloc_pages(GFP_KERNEL|__GFP_HIGHMEM|__GFP_REPEAT, 0);
37#else
38	page = alloc_pages(GFP_KERNEL|__GFP_REPEAT, 0);
39#endif
40	if (page)
41		clear_highpage(page);
42	flush_dcache_page(page);
43	return page;
44}
45
46void __set_pmd(pmd_t *pmdptr, unsigned long pmd)
47{
48	unsigned long *__ste_p = pmdptr->ste;
49	int loop;
50
51	if (!pmd) {
52		memset(__ste_p, 0, PME_SIZE);
53	}
54	else {
55		BUG_ON(pmd & (0x3f00 | xAMPRx_SS | 0xe));
56
57		for (loop = PME_SIZE; loop > 0; loop -= 4) {
58			*__ste_p++ = pmd;
59			pmd += __frv_PT_SIZE;
60		}
61	}
62
63	frv_dcache_writeback((unsigned long) pmdptr, (unsigned long) (pmdptr + 1));
64}
65
66/*
67 * List of all pgd's needed for non-PAE so it can invalidate entries
68 * in both cached and uncached pgd's; not needed for PAE since the
69 * kernel pmd is shared. If PAE were not to share the pmd a similar
70 * tactic would be needed. This is essentially codepath-based locking
71 * against pageattr.c; it is the unique case in which a valid change
72 * of kernel pagetables can't be lazily synchronized by vmalloc faults.
73 * vmalloc faults work because attached pagetables are never freed.
74 * If the locking proves to be non-performant, a ticketing scheme with
75 * checks at dup_mmap(), exec(), and other mmlist addition points
76 * could be used. The locking scheme was chosen on the basis of
77 * manfred's recommendations and having no core impact whatsoever.
78 * -- wli
79 */
80DEFINE_SPINLOCK(pgd_lock);
81struct page *pgd_list;
82
83static inline void pgd_list_add(pgd_t *pgd)
84{
85	struct page *page = virt_to_page(pgd);
86	page->index = (unsigned long) pgd_list;
87	if (pgd_list)
88		set_page_private(pgd_list, (unsigned long) &page->index);
89	pgd_list = page;
90	set_page_private(page, (unsigned long)&pgd_list);
91}
92
93static inline void pgd_list_del(pgd_t *pgd)
94{
95	struct page *next, **pprev, *page = virt_to_page(pgd);
96	next = (struct page *) page->index;
97	pprev = (struct page **) page_private(page);
98	*pprev = next;
99	if (next)
100		set_page_private(next, (unsigned long) pprev);
101}
102
103void pgd_ctor(void *pgd)
104{
105	unsigned long flags;
106
107	if (PTRS_PER_PMD == 1)
108		spin_lock_irqsave(&pgd_lock, flags);
109
110	memcpy((pgd_t *) pgd + USER_PGDS_IN_LAST_PML4,
111	       swapper_pg_dir + USER_PGDS_IN_LAST_PML4,
112	       (PTRS_PER_PGD - USER_PGDS_IN_LAST_PML4) * sizeof(pgd_t));
113
114	if (PTRS_PER_PMD > 1)
115		return;
116
117	pgd_list_add(pgd);
118	spin_unlock_irqrestore(&pgd_lock, flags);
119	memset(pgd, 0, USER_PGDS_IN_LAST_PML4 * sizeof(pgd_t));
120}
121
122/* never called when PTRS_PER_PMD > 1 */
123void pgd_dtor(void *pgd)
124{
125	unsigned long flags; /* can be called from interrupt context */
126
127	spin_lock_irqsave(&pgd_lock, flags);
128	pgd_list_del(pgd);
129	spin_unlock_irqrestore(&pgd_lock, flags);
130}
131
132pgd_t *pgd_alloc(struct mm_struct *mm)
133{
134	pgd_t *pgd;
135
136	pgd = quicklist_alloc(0, GFP_KERNEL, pgd_ctor);
137	if (!pgd)
138		return pgd;
139
140	return pgd;
141}
142
143void pgd_free(pgd_t *pgd)
144{
145	/* in the non-PAE case, clear_page_tables() clears user pgd entries */
146 	quicklist_free(0, pgd_dtor, pgd);
147}
148
149void __init pgtable_cache_init(void)
150{
151}
152
153void check_pgt_cache(void)
154{
155	quicklist_trim(0, pgd_dtor, 25, 16);
156}
157