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/gfp.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
 31pgtable_t 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		return NULL;
 42
 43	clear_highpage(page);
 44	if (!pgtable_page_ctor(page)) {
 45		__free_page(page);
 46		return NULL;
 47	}
 48	flush_dcache_page(page);
 49	return page;
 50}
 51
 52void __set_pmd(pmd_t *pmdptr, unsigned long pmd)
 53{
 54	unsigned long *__ste_p = pmdptr->ste;
 55	int loop;
 56
 57	if (!pmd) {
 58		memset(__ste_p, 0, PME_SIZE);
 59	}
 60	else {
 61		BUG_ON(pmd & (0x3f00 | xAMPRx_SS | 0xe));
 62
 63		for (loop = PME_SIZE; loop > 0; loop -= 4) {
 64			*__ste_p++ = pmd;
 65			pmd += __frv_PT_SIZE;
 66		}
 67	}
 68
 69	frv_dcache_writeback((unsigned long) pmdptr, (unsigned long) (pmdptr + 1));
 70}
 71
 72/*
 73 * List of all pgd's needed for non-PAE so it can invalidate entries
 74 * in both cached and uncached pgd's; not needed for PAE since the
 75 * kernel pmd is shared. If PAE were not to share the pmd a similar
 76 * tactic would be needed. This is essentially codepath-based locking
 77 * against pageattr.c; it is the unique case in which a valid change
 78 * of kernel pagetables can't be lazily synchronized by vmalloc faults.
 79 * vmalloc faults work because attached pagetables are never freed.
 80 * If the locking proves to be non-performant, a ticketing scheme with
 81 * checks at dup_mmap(), exec(), and other mmlist addition points
 82 * could be used. The locking scheme was chosen on the basis of
 83 * manfred's recommendations and having no core impact whatsoever.
 84 * -- nyc
 85 */
 86DEFINE_SPINLOCK(pgd_lock);
 87struct page *pgd_list;
 88
 89static inline void pgd_list_add(pgd_t *pgd)
 90{
 91	struct page *page = virt_to_page(pgd);
 92	page->index = (unsigned long) pgd_list;
 93	if (pgd_list)
 94		set_page_private(pgd_list, (unsigned long) &page->index);
 95	pgd_list = page;
 96	set_page_private(page, (unsigned long)&pgd_list);
 97}
 98
 99static inline void pgd_list_del(pgd_t *pgd)
100{
101	struct page *next, **pprev, *page = virt_to_page(pgd);
102	next = (struct page *) page->index;
103	pprev = (struct page **) page_private(page);
104	*pprev = next;
105	if (next)
106		set_page_private(next, (unsigned long) pprev);
107}
108
109void pgd_ctor(void *pgd)
110{
111	unsigned long flags;
112
113	if (PTRS_PER_PMD == 1)
114		spin_lock_irqsave(&pgd_lock, flags);
115
116	memcpy((pgd_t *) pgd + USER_PGDS_IN_LAST_PML4,
117	       swapper_pg_dir + USER_PGDS_IN_LAST_PML4,
118	       (PTRS_PER_PGD - USER_PGDS_IN_LAST_PML4) * sizeof(pgd_t));
119
120	if (PTRS_PER_PMD > 1)
121		return;
122
123	pgd_list_add(pgd);
124	spin_unlock_irqrestore(&pgd_lock, flags);
125	memset(pgd, 0, USER_PGDS_IN_LAST_PML4 * sizeof(pgd_t));
126}
127
128/* never called when PTRS_PER_PMD > 1 */
129void pgd_dtor(void *pgd)
130{
131	unsigned long flags; /* can be called from interrupt context */
132
133	spin_lock_irqsave(&pgd_lock, flags);
134	pgd_list_del(pgd);
135	spin_unlock_irqrestore(&pgd_lock, flags);
136}
137
138pgd_t *pgd_alloc(struct mm_struct *mm)
139{
140	return quicklist_alloc(0, GFP_KERNEL, pgd_ctor);
141}
142
143void pgd_free(struct mm_struct *mm, 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