/* *  linux/arch/arm/mm/mm-armo.c * *  Copyright (C) 1998-2000 Russell King * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * *  Page table sludge for older ARM processor architectures. */#include <linux/sched.h>#include <linux/mm.h>#include <linux/init.h>#include <linux/bootmem.h>#include <asm/pgtable.h>#include <asm/pgalloc.h>#include <asm/page.h>#include <asm/memory.h>#include <asm/hardware.h>#include <asm/map.h>#define MEMC_TABLE_SIZE (256*sizeof(unsigned long))kmem_cache_t *pte_cache, *pgd_cache;int page_nr;/* * Allocate space for a page table and a MEMC table. * Note that we place the MEMC * table before the page directory.  This means we can * easily get to both tightly-associated data structures * with a single pointer. */static inline pgd_t *alloc_pgd_table(void){	void *pg2k = kmem_cache_alloc(pgd_cache, GFP_KERNEL);	if (pg2k)		pg2k += MEMC_TABLE_SIZE;	return (pgd_t *)pg2k;}/* * Free a page table. this function is the counterpart to get_pgd_slow * below, not alloc_pgd_table above. */void free_pgd_slow(pgd_t *pgd){	unsigned long tbl = (unsigned long)pgd;	tbl -= MEMC_TABLE_SIZE;	kmem_cache_free(pgd_cache, (void *)tbl);}/* * Allocate a new pgd and fill it in ready for use * * A new tasks pgd is completely empty (all pages !present) except for: * * o The machine vectors at virtual address 0x0 * o The vmalloc region at the top of address space * */#define FIRST_KERNEL_PGD_NR     (FIRST_USER_PGD_NR + USER_PTRS_PER_PGD)pgd_t *get_pgd_slow(struct mm_struct *mm){	pgd_t *new_pgd, *init_pgd;	pmd_t *new_pmd, *init_pmd;	pte_t *new_pte, *init_pte;	new_pgd = alloc_pgd_table();	if (!new_pgd)		goto no_pgd;	/*	 * This lock is here just to satisfy pmd_alloc and pte_lock         * FIXME: I bet we could avoid taking it pretty much altogether	 */	spin_lock(&mm->page_table_lock);	/*	 * On ARM, first page must always be allocated since it contains	 * the machine vectors.	 */	new_pmd = pmd_alloc(mm, new_pgd, 0);	if (!new_pmd)		goto no_pmd;	new_pte = pte_alloc_kernel(mm, new_pmd, 0);	if (!new_pte)		goto no_pte;	init_pgd = pgd_offset(&init_mm, 0);	init_pmd = pmd_offset(init_pgd, 0);	init_pte = pte_offset(init_pmd, 0);	set_pte(new_pte, *init_pte);	/*	 * the page table entries are zeroed	 * when the table is created. (see the cache_ctor functions below)	 * Now we need to plonk the kernel (vmalloc) area at the end of	 * the address space. We copy this from the init thread, just like	 * the init_pte we copied above...	 */	memcpy(new_pgd + FIRST_KERNEL_PGD_NR, init_pgd + FIRST_KERNEL_PGD_NR,		(PTRS_PER_PGD - FIRST_KERNEL_PGD_NR) * sizeof(pgd_t));	spin_unlock(&mm->page_table_lock);	/* update MEMC tables */	cpu_memc_update_all(new_pgd);	return new_pgd;no_pte:	spin_unlock(&mm->page_table_lock);	pmd_free(new_pmd);	free_pgd_slow(new_pgd);	return NULL;no_pmd:	spin_unlock(&mm->page_table_lock);	free_pgd_slow(new_pgd);	return NULL;no_pgd:	return NULL;}/* * No special code is required here. */void setup_mm_for_reboot(char mode){}/* * This contains the code to setup the memory map on an ARM2/ARM250/ARM3 *  o swapper_pg_dir = 0x0207d000 *  o kernel proper starts at 0x0208000 *  o create (allocate) a pte to contain the machine vectors *  o populate the pte (points to 0x02078000) (FIXME - is it zeroed?) *  o populate the init tasks page directory (pgd) with the new pte *  o zero the rest of the init tasks pgdir (FIXME - what about vmalloc?!) */void __init memtable_init(struct meminfo *mi){	pte_t *pte;	int i;	page_nr = max_low_pfn;	pte = alloc_bootmem_low_pages(PTRS_PER_PTE * sizeof(pte_t));	pte[0] = mk_pte_phys(PAGE_OFFSET + SCREEN_SIZE, PAGE_READONLY);	pmd_populate(&init_mm, pmd_offset(swapper_pg_dir, 0), pte);	for (i = 1; i < PTRS_PER_PGD; i++)		pgd_val(swapper_pg_dir[i]) = 0;}void __init iotable_init(struct map_desc *io_desc){	/* nothing to do */}/* * We never have holes in the memmap */void __init create_memmap_holes(struct meminfo *mi){}static void pte_cache_ctor(void *pte, kmem_cache_t *cache, unsigned long flags){	memzero(pte, sizeof(pte_t) * PTRS_PER_PTE);}static void pgd_cache_ctor(void *pgd, kmem_cache_t *cache, unsigned long flags){	memzero(pgd + MEMC_TABLE_SIZE, USER_PTRS_PER_PGD * sizeof(pgd_t));}void __init pgtable_cache_init(void){	pte_cache = kmem_cache_create("pte-cache",				sizeof(pte_t) * PTRS_PER_PTE,				0, 0, pte_cache_ctor, NULL);	if (!pte_cache)		BUG();	pgd_cache = kmem_cache_create("pgd-cache", MEMC_TABLE_SIZE +				sizeof(pgd_t) * PTRS_PER_PGD,				0, 0, pgd_cache_ctor, NULL);	if (!pgd_cache)		BUG();}