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		clear_highpage(page);
 42		pgtable_page_ctor(page);
 43		flush_dcache_page(page);
 44	}
 45	return page;
 46}
 47
 48void __set_pmd(pmd_t *pmdptr, unsigned long pmd)
 49{
 50	unsigned long *__ste_p = pmdptr->ste;
 51	int loop;
 52
 53	if (!pmd) {
 54		memset(__ste_p, 0, PME_SIZE);
 55	}
 56	else {
 57		BUG_ON(pmd & (0x3f00 | xAMPRx_SS | 0xe));
 58
 59		for (loop = PME_SIZE; loop > 0; loop -= 4) {
 60			*__ste_p++ = pmd;
 61			pmd += __frv_PT_SIZE;
 62		}
 63	}
 64
 65	frv_dcache_writeback((unsigned long) pmdptr, (unsigned long) (pmdptr + 1));
 66}
 67
 68/*
 69 * List of all pgd's needed for non-PAE so it can invalidate entries
 70 * in both cached and uncached pgd's; not needed for PAE since the
 71 * kernel pmd is shared. If PAE were not to share the pmd a similar
 72 * tactic would be needed. This is essentially codepath-based locking
 73 * against pageattr.c; it is the unique case in which a valid change
 74 * of kernel pagetables can't be lazily synchronized by vmalloc faults.
 75 * vmalloc faults work because attached pagetables are never freed.
 76 * If the locking proves to be non-performant, a ticketing scheme with
 77 * checks at dup_mmap(), exec(), and other mmlist addition points
 78 * could be used. The locking scheme was chosen on the basis of
 79 * manfred's recommendations and having no core impact whatsoever.
 80 * -- wli
 81 */
 82DEFINE_SPINLOCK(pgd_lock);
 83struct page *pgd_list;
 84
 85static inline void pgd_list_add(pgd_t *pgd)
 86{
 87	struct page *page = virt_to_page(pgd);
 88	page->index = (unsigned long) pgd_list;
 89	if (pgd_list)
 90		set_page_private(pgd_list, (unsigned long) &page->index);
 91	pgd_list = page;
 92	set_page_private(page, (unsigned long)&pgd_list);
 93}
 94
 95static inline void pgd_list_del(pgd_t *pgd)
 96{
 97	struct page *next, **pprev, *page = virt_to_page(pgd);
 98	next = (struct page *) page->index;
 99	pprev = (struct page **) page_private(page);
100	*pprev = next;
101	if (next)
102		set_page_private(next, (unsigned long) pprev);
103}
104
105void pgd_ctor(void *pgd)
106{
107	unsigned long flags;
108
109	if (PTRS_PER_PMD == 1)
110		spin_lock_irqsave(&pgd_lock, flags);
111
112	memcpy((pgd_t *) pgd + USER_PGDS_IN_LAST_PML4,
113	       swapper_pg_dir + USER_PGDS_IN_LAST_PML4,
114	       (PTRS_PER_PGD - USER_PGDS_IN_LAST_PML4) * sizeof(pgd_t));
115
116	if (PTRS_PER_PMD > 1)
117		return;
118
119	pgd_list_add(pgd);
120	spin_unlock_irqrestore(&pgd_lock, flags);
121	memset(pgd, 0, USER_PGDS_IN_LAST_PML4 * sizeof(pgd_t));
122}
123
124/* never called when PTRS_PER_PMD > 1 */
125void pgd_dtor(void *pgd)
126{
127	unsigned long flags; /* can be called from interrupt context */
128
129	spin_lock_irqsave(&pgd_lock, flags);
130	pgd_list_del(pgd);
131	spin_unlock_irqrestore(&pgd_lock, flags);
132}
133
134pgd_t *pgd_alloc(struct mm_struct *mm)
135{
136	return quicklist_alloc(0, GFP_KERNEL, pgd_ctor);
137}
138
139void pgd_free(struct mm_struct *mm, pgd_t *pgd)
140{
141	/* in the non-PAE case, clear_page_tables() clears user pgd entries */
142 	quicklist_free(0, pgd_dtor, pgd);
143}
144
145void __init pgtable_cache_init(void)
146{
147}
148
149void check_pgt_cache(void)
150{
151	quicklist_trim(0, pgd_dtor, 25, 16);
152}
153