original_kernel/arch/sh/mm/pg-sh4.c

/*
 * arch/sh/mm/pg-sh4.c
 *
 * Copyright (C) 1999, 2000, 2002  Niibe Yutaka
 * Copyright (C) 2002 - 2005  Paul Mundt
 *
 * Released under the terms of the GNU GPL v2.0.
 */
#include <linux/mm.h>
#include <linux/mutex.h>
#include <asm/mmu_context.h>
#include <asm/cacheflush.h>

extern struct mutex p3map_mutex[];

#define CACHE_ALIAS (current_cpu_data.dcache.alias_mask)

/*
 * clear_user_page
 * @to: P1 address
 * @address: U0 address to be mapped
 * @page: page (virt_to_page(to))
 */
void clear_user_page(void *to, unsigned long address, struct page *page)
{
	__set_bit(PG_mapped, &page->flags);
	if (((address ^ (unsigned long)to) & CACHE_ALIAS) == 0)
		clear_page(to);
	else {
		unsigned long phys_addr = PHYSADDR(to);
		unsigned long p3_addr = P3SEG + (address & CACHE_ALIAS);
		pgd_t *pgd = pgd_offset_k(p3_addr);
		pud_t *pud = pud_offset(pgd, p3_addr);
		pmd_t *pmd = pmd_offset(pud, p3_addr);
		pte_t *pte = pte_offset_kernel(pmd, p3_addr);
		pte_t entry;
		unsigned long flags;

		entry = pfn_pte(phys_addr >> PAGE_SHIFT, PAGE_KERNEL);
		mutex_lock(&p3map_mutex[(address & CACHE_ALIAS)>>12]);
		set_pte(pte, entry);
		local_irq_save(flags);
		flush_tlb_one(get_asid(), p3_addr);
		local_irq_restore(flags);
		update_mmu_cache(NULL, p3_addr, entry);
		__clear_user_page((void *)p3_addr, to);
		pte_clear(&init_mm, p3_addr, pte);
		mutex_unlock(&p3map_mutex[(address & CACHE_ALIAS)>>12]);
	}
}

/*
 * copy_user_page
 * @to: P1 address
 * @from: P1 address
 * @address: U0 address to be mapped
 * @page: page (virt_to_page(to))
 */
void copy_user_page(void *to, void *from, unsigned long address,
		    struct page *page)
{
	__set_bit(PG_mapped, &page->flags);
	if (((address ^ (unsigned long)to) & CACHE_ALIAS) == 0)
		copy_page(to, from);
	else {
		unsigned long phys_addr = PHYSADDR(to);
		unsigned long p3_addr = P3SEG + (address & CACHE_ALIAS);
		pgd_t *pgd = pgd_offset_k(p3_addr);
		pud_t *pud = pud_offset(pgd, p3_addr);
		pmd_t *pmd = pmd_offset(pud, p3_addr);
		pte_t *pte = pte_offset_kernel(pmd, p3_addr);
		pte_t entry;
		unsigned long flags;

		entry = pfn_pte(phys_addr >> PAGE_SHIFT, PAGE_KERNEL);
		mutex_lock(&p3map_mutex[(address & CACHE_ALIAS)>>12]);
		set_pte(pte, entry);
		local_irq_save(flags);
		flush_tlb_one(get_asid(), p3_addr);
		local_irq_restore(flags);
		update_mmu_cache(NULL, p3_addr, entry);
		__copy_user_page((void *)p3_addr, from, to);
		pte_clear(&init_mm, p3_addr, pte);
		mutex_unlock(&p3map_mutex[(address & CACHE_ALIAS)>>12]);
	}
}

/*
 * For SH-4, we have our own implementation for ptep_get_and_clear
 */
inline pte_t ptep_get_and_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
{
	pte_t pte = *ptep;

	pte_clear(mm, addr, ptep);
	if (!pte_not_present(pte)) {
		unsigned long pfn = pte_pfn(pte);
		if (pfn_valid(pfn)) {
			struct page *page = pfn_to_page(pfn);
			struct address_space *mapping = page_mapping(page);
			if (!mapping || !mapping_writably_mapped(mapping))
				__clear_bit(PG_mapped, &page->flags);
		}
	}
	return pte;
}