path: root/arch/arm/mm/mmu.c

/*
 *  linux/arch/arm/mm/mmu.c
 *
 *  Copyright (C) 1995-2005 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.
 */
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/bootmem.h>
#include <linux/mman.h>
#include <linux/nodemask.h>

#include <asm/cputype.h>
#include <asm/mach-types.h>
#include <asm/setup.h>
#include <asm/sizes.h>
#include <asm/tlb.h>

#include <asm/mach/arch.h>
#include <asm/mach/map.h>

#include "mm.h"

DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);

/*
 * empty_zero_page is a special page that is used for
 * zero-initialized data and COW.
 */
struct page *empty_zero_page;
EXPORT_SYMBOL(empty_zero_page);

/*
 * The pmd table for the upper-most set of pages.
 */
pmd_t *top_pmd;

#define CPOLICY_UNCACHED	0
#define CPOLICY_BUFFERED	1
#define CPOLICY_WRITETHROUGH	2
#define CPOLICY_WRITEBACK	3
#define CPOLICY_WRITEALLOC	4

static unsigned int cachepolicy __initdata = CPOLICY_WRITEBACK;
static unsigned int ecc_mask __initdata = 0;
pgprot_t pgprot_user;
pgprot_t pgprot_kernel;

EXPORT_SYMBOL(pgprot_user);
EXPORT_SYMBOL(pgprot_kernel);

struct cachepolicy {
	const char	policy[16];
	unsigned int	cr_mask;
	unsigned int	pmd;
	unsigned int	pte;
};

static struct cachepolicy cache_policies[] __initdata = {
	{
		.policy		= "uncached",
		.cr_mask	= CR_W|CR_C,
		.pmd		= PMD_SECT_UNCACHED,
		.pte		= L_PTE_MT_UNCACHED,
	}, {
		.policy		= "buffered",
		.cr_mask	= CR_C,
		.pmd		= PMD_SECT_BUFFERED,
		.pte		= L_PTE_MT_BUFFERABLE,
	}, {
		.policy		= "writethrough",
		.cr_mask	= 0,
		.pmd		= PMD_SECT_WT,
		.pte		= L_PTE_MT_WRITETHROUGH,
	}, {
		.policy		= "writeback",
		.cr_mask	= 0,
		.pmd		= PMD_SECT_WB,
		.pte		= L_PTE_MT_WRITEBACK,
	}, {
		.policy		= "writealloc",
		.cr_mask	= 0,
		.pmd		= PMD_SECT_WBWA,
		.pte		= L_PTE_MT_WRITEALLOC,
	}
};

/*
 * These are useful for identifying cache coherency
 * problems by allowing the cache or the cache and
 * writebuffer to be turned off.  (Note: the write
 * buffer should not be on and the cache off).
 */
static void __init early_cachepolicy(char **p)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(cache_policies); i++) {
		int len = strlen(cache_policies[i].policy);

		if (memcmp(*p, cache_policies[i].policy, len) == 0) {
			cachepolicy = i;
			cr_alignment &= ~cache_policies[i].cr_mask;
			cr_no_alignment &= ~cache_policies[i].cr_mask;
			*p += len;
			break;
		}
	}
	if (i == ARRAY_SIZE(cache_policies))
		printk(KERN_ERR "ERROR: unknown or unsupported cache policy\n");
	if (cpu_architecture() >= CPU_ARCH_ARMv6) {
		printk(KERN_WARNING "Only cachepolicy=writeback supported on ARMv6 and later\n");
		cachepolicy = CPOLICY_WRITEBACK;
	}
	flush_cache_all();
	set_cr(cr_alignment);
}
__early_param("cachepolicy=", early_cachepolicy);

static void __init early_nocache(char **__unused)
{
	char *p = "buffered";
	printk(KERN_WARNING "nocache is deprecated; use cachepolicy=%s\n", p);
	early_cachepolicy(&p);
}
__early_param("nocache", early_nocache);

static void __init early_nowrite(char **__unused)
{
	char *p = "uncached";
	printk(KERN_WARNING "nowb is deprecated; use cachepolicy=%s\n", p);
	early_cachepolicy(&p);
}
__early_param("nowb", early_nowrite);

static void __init early_ecc(char **p)
{
	if (memcmp(*p, "on", 2) == 0) {
		ecc_mask = PMD_PROTECTION;
		*p += 2;
	} else if (memcmp(*p, "off", 3) == 0) {
		ecc_mask = 0;
		*p += 3;
	}
}
__early_param("ecc=", early_ecc);

static int __init noalign_setup(char *__unused)
{
	cr_alignment &= ~CR_A;
	cr_no_alignment &= ~CR_A;
	set_cr(cr_alignment);
	return 1;
}
__setup("noalign", noalign_setup);

#ifndef CONFIG_SMP
void adjust_cr(unsigned long mask, unsigned long set)
{
	unsigned long flags;

	mask &= ~CR_A;

	set &= mask;

	local_irq_save(flags);

	cr_no_alignment = (cr_no_alignment & ~mask) | set;
	cr_alignment = (cr_alignment & ~mask) | set;

	set_cr((get_cr() & ~mask) | set);