160 lines
4.0 KiB
C
160 lines
4.0 KiB
C
/* pgalloc.c: page directory & page table allocation
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*
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* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/mm.h>
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#include <linux/highmem.h>
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#include <linux/quicklist.h>
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#include <asm/pgalloc.h>
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#include <asm/page.h>
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#include <asm/cacheflush.h>
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pgd_t swapper_pg_dir[PTRS_PER_PGD] __attribute__((aligned(PAGE_SIZE)));
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pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
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{
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pte_t *pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_REPEAT);
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if (pte)
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clear_page(pte);
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return pte;
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}
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pgtable_t pte_alloc_one(struct mm_struct *mm, unsigned long address)
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{
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struct page *page;
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#ifdef CONFIG_HIGHPTE
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page = alloc_pages(GFP_KERNEL|__GFP_HIGHMEM|__GFP_REPEAT, 0);
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#else
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page = alloc_pages(GFP_KERNEL|__GFP_REPEAT, 0);
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#endif
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if (page) {
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clear_highpage(page);
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pgtable_page_ctor(page);
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flush_dcache_page(page);
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}
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return page;
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}
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void __set_pmd(pmd_t *pmdptr, unsigned long pmd)
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{
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unsigned long *__ste_p = pmdptr->ste;
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int loop;
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if (!pmd) {
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memset(__ste_p, 0, PME_SIZE);
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}
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else {
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BUG_ON(pmd & (0x3f00 | xAMPRx_SS | 0xe));
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for (loop = PME_SIZE; loop > 0; loop -= 4) {
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*__ste_p++ = pmd;
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pmd += __frv_PT_SIZE;
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}
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}
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frv_dcache_writeback((unsigned long) pmdptr, (unsigned long) (pmdptr + 1));
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}
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/*
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* List of all pgd's needed for non-PAE so it can invalidate entries
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* in both cached and uncached pgd's; not needed for PAE since the
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* kernel pmd is shared. If PAE were not to share the pmd a similar
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* tactic would be needed. This is essentially codepath-based locking
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* against pageattr.c; it is the unique case in which a valid change
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* of kernel pagetables can't be lazily synchronized by vmalloc faults.
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* vmalloc faults work because attached pagetables are never freed.
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* If the locking proves to be non-performant, a ticketing scheme with
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* checks at dup_mmap(), exec(), and other mmlist addition points
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* could be used. The locking scheme was chosen on the basis of
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* manfred's recommendations and having no core impact whatsoever.
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* -- wli
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*/
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DEFINE_SPINLOCK(pgd_lock);
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struct page *pgd_list;
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static inline void pgd_list_add(pgd_t *pgd)
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{
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struct page *page = virt_to_page(pgd);
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page->index = (unsigned long) pgd_list;
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if (pgd_list)
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set_page_private(pgd_list, (unsigned long) &page->index);
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pgd_list = page;
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set_page_private(page, (unsigned long)&pgd_list);
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}
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static inline void pgd_list_del(pgd_t *pgd)
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{
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struct page *next, **pprev, *page = virt_to_page(pgd);
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next = (struct page *) page->index;
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pprev = (struct page **) page_private(page);
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*pprev = next;
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if (next)
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set_page_private(next, (unsigned long) pprev);
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}
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void pgd_ctor(void *pgd)
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{
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unsigned long flags;
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if (PTRS_PER_PMD == 1)
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spin_lock_irqsave(&pgd_lock, flags);
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memcpy((pgd_t *) pgd + USER_PGDS_IN_LAST_PML4,
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swapper_pg_dir + USER_PGDS_IN_LAST_PML4,
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(PTRS_PER_PGD - USER_PGDS_IN_LAST_PML4) * sizeof(pgd_t));
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if (PTRS_PER_PMD > 1)
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return;
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pgd_list_add(pgd);
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spin_unlock_irqrestore(&pgd_lock, flags);
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memset(pgd, 0, USER_PGDS_IN_LAST_PML4 * sizeof(pgd_t));
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}
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/* never called when PTRS_PER_PMD > 1 */
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void pgd_dtor(void *pgd)
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{
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unsigned long flags; /* can be called from interrupt context */
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spin_lock_irqsave(&pgd_lock, flags);
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pgd_list_del(pgd);
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spin_unlock_irqrestore(&pgd_lock, flags);
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}
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pgd_t *pgd_alloc(struct mm_struct *mm)
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{
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pgd_t *pgd;
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pgd = quicklist_alloc(0, GFP_KERNEL, pgd_ctor);
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if (!pgd)
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return pgd;
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return pgd;
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}
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void pgd_free(struct mm_struct *mm, pgd_t *pgd)
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{
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/* in the non-PAE case, clear_page_tables() clears user pgd entries */
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quicklist_free(0, pgd_dtor, pgd);
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}
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void __init pgtable_cache_init(void)
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{
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}
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void check_pgt_cache(void)
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{
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quicklist_trim(0, pgd_dtor, 25, 16);
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}
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