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/* 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/gfp.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/quicklist.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)));
pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
{
pte_t *pte = (pte_t *)__get_free_page(GFP_KERNEL);
if (pte)
clear_page(pte);
return pte;
}
pgtable_t pte_alloc_one(struct mm_struct *mm, unsigned long address)
{
struct page *page;
#ifdef CONFIG_HIGHPTE
page = alloc_pages(GFP_KERNEL|__GFP_HIGHMEM, 0);
#else
page = alloc_pages(GFP_KERNEL, 0);
#endif
if (!page)
return NULL;
clear_highpage(page);
if (!pgtable_page_ctor(page)) {
__free_page(page);
return NULL;
}
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.
* -- nyc
*/
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)
set_page_private(pgd_list, (unsigned long) &page->index);
pgd_list = page;
set_page_private(page, (unsigned long)&pgd_list);
}
static inline void pgd_list_del(pgd_t *pgd)
{
struct page *next, **pprev, *page = virt_to_page(pgd);
next = (struct page *) page->index;
pprev = (struct page **) page_private(page);
*pprev = next;
if (next)
set_page_private(next, (unsigned long) pprev);
}
void pgd_ctor(void *pgd)
{
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 */
void pgd_dtor(void *pgd)
{
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)
{
return quicklist_alloc(0, GFP_KERNEL, pgd_ctor);
}
void pgd_free(struct mm_struct *mm, pgd_t *pgd)
{
/* in the non-PAE case, clear_page_tables() clears user pgd entries */
quicklist_free(0, pgd_dtor, pgd);
}
void __init pgtable_cache_init(void)
{
}
void check_pgt_cache(void)
{
quicklist_trim(0, pgd_dtor, 25, 16);
}
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