pgalloc.c 4.18 KB
Newer Older
Linus Torvalds's avatar
Linus Torvalds committed
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
/* pgalloc.c: page directory & page table allocation
 *
 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <asm/pgalloc.h>
#include <asm/page.h>
#include <asm/cacheflush.h>

pgd_t swapper_pg_dir[PTRS_PER_PGD] __attribute__((aligned(PAGE_SIZE)));
21
struct kmem_cache *pgd_cache;
Linus Torvalds's avatar
Linus Torvalds committed
22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87

pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
{
	pte_t *pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_REPEAT);
	if (pte)
		clear_page(pte);
	return pte;
}

struct page *pte_alloc_one(struct mm_struct *mm, unsigned long address)
{
	struct page *page;

#ifdef CONFIG_HIGHPTE
	page = alloc_pages(GFP_KERNEL|__GFP_HIGHMEM|__GFP_REPEAT, 0);
#else
	page = alloc_pages(GFP_KERNEL|__GFP_REPEAT, 0);
#endif
	if (page)
		clear_highpage(page);
	flush_dcache_page(page);
	return page;
}

void __set_pmd(pmd_t *pmdptr, unsigned long pmd)
{
	unsigned long *__ste_p = pmdptr->ste;
	int loop;

	if (!pmd) {
		memset(__ste_p, 0, PME_SIZE);
	}
	else {
		BUG_ON(pmd & (0x3f00 | xAMPRx_SS | 0xe));

		for (loop = PME_SIZE; loop > 0; loop -= 4) {
			*__ste_p++ = pmd;
			pmd += __frv_PT_SIZE;
		}
	}

	frv_dcache_writeback((unsigned long) pmdptr, (unsigned long) (pmdptr + 1));
}

/*
 * List of all pgd's needed for non-PAE so it can invalidate entries
 * in both cached and uncached pgd's; not needed for PAE since the
 * kernel pmd is shared. If PAE were not to share the pmd a similar
 * tactic would be needed. This is essentially codepath-based locking
 * against pageattr.c; it is the unique case in which a valid change
 * of kernel pagetables can't be lazily synchronized by vmalloc faults.
 * vmalloc faults work because attached pagetables are never freed.
 * If the locking proves to be non-performant, a ticketing scheme with
 * checks at dup_mmap(), exec(), and other mmlist addition points
 * could be used. The locking scheme was chosen on the basis of
 * manfred's recommendations and having no core impact whatsoever.
 * -- wli
 */
DEFINE_SPINLOCK(pgd_lock);
struct page *pgd_list;

static inline void pgd_list_add(pgd_t *pgd)
{
	struct page *page = virt_to_page(pgd);
	page->index = (unsigned long) pgd_list;
	if (pgd_list)
88
		set_page_private(pgd_list, (unsigned long) &page->index);
Linus Torvalds's avatar
Linus Torvalds committed
89
	pgd_list = page;
90
	set_page_private(page, (unsigned long)&pgd_list);
Linus Torvalds's avatar
Linus Torvalds committed
91 92 93 94 95 96
}

static inline void pgd_list_del(pgd_t *pgd)
{
	struct page *next, **pprev, *page = virt_to_page(pgd);
	next = (struct page *) page->index;
97
	pprev = (struct page **) page_private(page);
Linus Torvalds's avatar
Linus Torvalds committed
98 99
	*pprev = next;
	if (next)
100
		set_page_private(next, (unsigned long) pprev);
Linus Torvalds's avatar
Linus Torvalds committed
101 102
}

103
void pgd_ctor(void *pgd, struct kmem_cache *cache, unsigned long unused)
Linus Torvalds's avatar
Linus Torvalds committed
104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122
{
	unsigned long flags;

	if (PTRS_PER_PMD == 1)
		spin_lock_irqsave(&pgd_lock, flags);

	memcpy((pgd_t *) pgd + USER_PGDS_IN_LAST_PML4,
	       swapper_pg_dir + USER_PGDS_IN_LAST_PML4,
	       (PTRS_PER_PGD - USER_PGDS_IN_LAST_PML4) * sizeof(pgd_t));

	if (PTRS_PER_PMD > 1)
		return;

	pgd_list_add(pgd);
	spin_unlock_irqrestore(&pgd_lock, flags);
	memset(pgd, 0, USER_PGDS_IN_LAST_PML4 * sizeof(pgd_t));
}

/* never called when PTRS_PER_PMD > 1 */
123
void pgd_dtor(void *pgd, struct kmem_cache *cache, unsigned long unused)
Linus Torvalds's avatar
Linus Torvalds committed
124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159
{
	unsigned long flags; /* can be called from interrupt context */

	spin_lock_irqsave(&pgd_lock, flags);
	pgd_list_del(pgd);
	spin_unlock_irqrestore(&pgd_lock, flags);
}

pgd_t *pgd_alloc(struct mm_struct *mm)
{
	pgd_t *pgd;

	pgd = kmem_cache_alloc(pgd_cache, GFP_KERNEL);
	if (!pgd)
		return pgd;

	return pgd;
}

void pgd_free(pgd_t *pgd)
{
	/* in the non-PAE case, clear_page_tables() clears user pgd entries */
	kmem_cache_free(pgd_cache, pgd);
}

void __init pgtable_cache_init(void)
{
	pgd_cache = kmem_cache_create("pgd",
				      PTRS_PER_PGD * sizeof(pgd_t),
				      PTRS_PER_PGD * sizeof(pgd_t),
				      0,
				      pgd_ctor,
				      pgd_dtor);
	if (!pgd_cache)
		panic("pgtable_cache_init(): Cannot create pgd cache");
}