Pull ec into test branch

[mirror_ubuntu-bionic-kernel.git] / 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/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);

extern void _stext, _etext, __data_start, _end;
extern pgd_t swapper_pg_dir[PTRS_PER_PGD];

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

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            = 0,
        }, {
                .policy         = "buffered",
                .cr_mask        = CR_C,
                .pmd            = PMD_SECT_BUFFERED,
                .pte            = PTE_BUFFERABLE,
        }, {
                .policy         = "writethrough",
                .cr_mask        = 0,
                .pmd            = PMD_SECT_WT,
                .pte            = PTE_CACHEABLE,
        }, {
                .policy         = "writeback",
                .cr_mask        = 0,
                .pmd            = PMD_SECT_WB,
                .pte            = PTE_BUFFERABLE|PTE_CACHEABLE,
        }, {
                .policy         = "writealloc",
                .cr_mask        = 0,
                .pmd            = PMD_SECT_WBWA,
                .pte            = PTE_BUFFERABLE|PTE_CACHEABLE,
        }
};

/*
 * These are useful for identifing 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");
        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);

struct mem_types {
        unsigned int    prot_pte;
        unsigned int    prot_l1;
        unsigned int    prot_sect;
        unsigned int    domain;
};

static struct mem_types mem_types[] __initdata = {
        [MT_DEVICE] = {
                .prot_pte  = L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY |
                                L_PTE_WRITE,
                .prot_l1   = PMD_TYPE_TABLE,
                .prot_sect = PMD_TYPE_SECT | PMD_BIT4 | PMD_SECT_UNCACHED |
                                PMD_SECT_AP_WRITE,
                .domain    = DOMAIN_IO,
        },
        [MT_CACHECLEAN] = {
                .prot_sect = PMD_TYPE_SECT | PMD_BIT4,
                .domain    = DOMAIN_KERNEL,
        },
        [MT_MINICLEAN] = {
                .prot_sect = PMD_TYPE_SECT | PMD_BIT4 | PMD_SECT_MINICACHE,
                .domain    = DOMAIN_KERNEL,
        },
        [MT_LOW_VECTORS] = {
                .prot_pte  = L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY |
                                L_PTE_EXEC,
                .prot_l1   = PMD_TYPE_TABLE,
                .domain    = DOMAIN_USER,
        },
        [MT_HIGH_VECTORS] = {
                .prot_pte  = L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY |
                                L_PTE_USER | L_PTE_EXEC,
                .prot_l1   = PMD_TYPE_TABLE,
                .domain    = DOMAIN_USER,
        },
        [MT_MEMORY] = {
                .prot_sect = PMD_TYPE_SECT | PMD_BIT4 | PMD_SECT_AP_WRITE,
                .domain    = DOMAIN_KERNEL,
        },
        [MT_ROM] = {
                .prot_sect = PMD_TYPE_SECT | PMD_BIT4,
                .domain    = DOMAIN_KERNEL,
        },
        [MT_IXP2000_DEVICE] = { /* IXP2400 requires XCB=101 for on-chip I/O */
                .prot_pte  = L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY |
                                L_PTE_WRITE,
                .prot_l1   = PMD_TYPE_TABLE,
                .prot_sect = PMD_TYPE_SECT | PMD_BIT4 | PMD_SECT_UNCACHED |
                                PMD_SECT_AP_WRITE | PMD_SECT_BUFFERABLE |
                                PMD_SECT_TEX(1),
                .domain    = DOMAIN_IO,
        },
        [MT_NONSHARED_DEVICE] = {
                .prot_l1   = PMD_TYPE_TABLE,
                .prot_sect = PMD_TYPE_SECT | PMD_BIT4 | PMD_SECT_NONSHARED_DEV |
                                PMD_SECT_AP_WRITE,
                .domain    = DOMAIN_IO,
        }
};

/*
 * Adjust the PMD section entries according to the CPU in use.
 */
static void __init build_mem_type_table(void)
{
        struct cachepolicy *cp;
        unsigned int cr = get_cr();
        unsigned int user_pgprot, kern_pgprot;
        int cpu_arch = cpu_architecture();
        int i;

#if defined(CONFIG_CPU_DCACHE_DISABLE)
        if (cachepolicy > CPOLICY_BUFFERED)
                cachepolicy = CPOLICY_BUFFERED;
#elif defined(CONFIG_CPU_DCACHE_WRITETHROUGH)
        if (cachepolicy > CPOLICY_WRITETHROUGH)
                cachepolicy = CPOLICY_WRITETHROUGH;
#endif
        if (cpu_arch < CPU_ARCH_ARMv5) {
                if (cachepolicy >= CPOLICY_WRITEALLOC)
                        cachepolicy = CPOLICY_WRITEBACK;
                ecc_mask = 0;
        }

        /*
         * Xscale must not have PMD bit 4 set for section mappings.
         */
        if (cpu_is_xscale())
                for (i = 0; i < ARRAY_SIZE(mem_types); i++)
                        mem_types[i].prot_sect &= ~PMD_BIT4;

        /*
         * ARMv5 and lower, excluding Xscale, bit 4 must be set for
         * page tables.
         */
        if (cpu_arch < CPU_ARCH_ARMv6 && !cpu_is_xscale())
                for (i = 0; i < ARRAY_SIZE(mem_types); i++)
                        if (mem_types[i].prot_l1)
                                mem_types[i].prot_l1 |= PMD_BIT4;

        cp = &cache_policies[cachepolicy];
        kern_pgprot = user_pgprot = cp->pte;

        /*
         * Enable CPU-specific coherency if supported.
         * (Only available on XSC3 at the moment.)
         */
        if (arch_is_coherent()) {
                if (cpu_is_xsc3()) {
                        mem_types[MT_MEMORY].prot_sect |= PMD_SECT_S;
                        mem_types[MT_MEMORY].prot_pte |= L_PTE_SHARED;
                }
        }

        /*
         * ARMv6 and above have extended page tables.
         */
        if (cpu_arch >= CPU_ARCH_ARMv6 && (cr & CR_XP)) {
                /*
                 * bit 4 becomes XN which we must clear for the
                 * kernel memory mapping.
                 */
                mem_types[MT_MEMORY].prot_sect &= ~PMD_SECT_XN;
                mem_types[MT_ROM].prot_sect &= ~PMD_SECT_XN;

                /*
                 * Mark cache clean areas and XIP ROM read only
                 * from SVC mode and no access from userspace.
                 */
                mem_types[MT_ROM].prot_sect |= PMD_SECT_APX|PMD_SECT_AP_WRITE;
                mem_types[MT_MINICLEAN].prot_sect |= PMD_SECT_APX|PMD_SECT_AP_WRITE;
                mem_types[MT_CACHECLEAN].prot_sect |= PMD_SECT_APX|PMD_SECT_AP_WRITE;

                /*
                 * Mark the device area as "shared device"
                 */
                mem_types[MT_DEVICE].prot_pte |= L_PTE_BUFFERABLE;
                mem_types[MT_DEVICE].prot_sect |= PMD_SECT_BUFFERED;

#ifdef CONFIG_SMP
                /*
                 * Mark memory with the "shared" attribute for SMP systems
                 */
                user_pgprot |= L_PTE_SHARED;
                kern_pgprot |= L_PTE_SHARED;
                mem_types[MT_MEMORY].prot_sect |= PMD_SECT_S;
#endif
        }

        for (i = 0; i < 16; i++) {
                unsigned long v = pgprot_val(protection_map[i]);
                v = (v & ~(L_PTE_BUFFERABLE|L_PTE_CACHEABLE)) | user_pgprot;
                protection_map[i] = __pgprot(v);
        }

        mem_types[MT_LOW_VECTORS].prot_pte |= kern_pgprot;
        mem_types[MT_HIGH_VECTORS].prot_pte |= kern_pgprot;

        if (cpu_arch >= CPU_ARCH_ARMv5) {
#ifndef CONFIG_SMP
                /*
                 * Only use write-through for non-SMP systems
                 */
                mem_types[MT_LOW_VECTORS].prot_pte &= ~L_PTE_BUFFERABLE;
                mem_types[MT_HIGH_VECTORS].prot_pte &= ~L_PTE_BUFFERABLE;
#endif
        } else {
                mem_types[MT_MINICLEAN].prot_sect &= ~PMD_SECT_TEX(1);
        }

        pgprot_kernel = __pgprot(L_PTE_PRESENT | L_PTE_YOUNG |
                                 L_PTE_DIRTY | L_PTE_WRITE |
                                 L_PTE_EXEC | kern_pgprot);

        mem_types[MT_LOW_VECTORS].prot_l1 |= ecc_mask;
        mem_types[MT_HIGH_VECTORS].prot_l1 |= ecc_mask;
        mem_types[MT_MEMORY].prot_sect |= ecc_mask | cp->pmd;
        mem_types[MT_ROM].prot_sect |= cp->pmd;

        switch (cp->pmd) {
        case PMD_SECT_WT:
                mem_types[MT_CACHECLEAN].prot_sect |= PMD_SECT_WT;
                break;
        case PMD_SECT_WB:
        case PMD_SECT_WBWA:
                mem_types[MT_CACHECLEAN].prot_sect |= PMD_SECT_WB;
                break;
        }
        printk("Memory policy: ECC %sabled, Data cache %s\n",
                ecc_mask ? "en" : "dis", cp->policy);
}

#define vectors_base()  (vectors_high() ? 0xffff0000 : 0)

/*
 * Create a SECTION PGD between VIRT and PHYS in domain
 * DOMAIN with protection PROT.  This operates on half-
 * pgdir entry increments.
 */
static inline void
alloc_init_section(unsigned long virt, unsigned long phys, int prot)
{
        pmd_t *pmdp = pmd_off_k(virt);

        if (virt & (1 << 20))
                pmdp++;

        *pmdp = __pmd(phys | prot);
        flush_pmd_entry(pmdp);
}

/*
 * Create a SUPER SECTION PGD between VIRT and PHYS with protection PROT
 */
static inline void
alloc_init_supersection(unsigned long virt, unsigned long phys, int prot)
{
        int i;

        for (i = 0; i < 16; i += 1) {
                alloc_init_section(virt, phys, prot | PMD_SECT_SUPER);

                virt += (PGDIR_SIZE / 2);
        }
}

/*
 * Add a PAGE mapping between VIRT and PHYS in domain
 * DOMAIN with protection PROT.  Note that due to the
 * way we map the PTEs, we must allocate two PTE_SIZE'd
 * blocks - one for the Linux pte table, and one for
 * the hardware pte table.
 */
static inline void
alloc_init_page(unsigned long virt, unsigned long phys, unsigned int prot_l1, pgprot_t prot)
{
        pmd_t *pmdp = pmd_off_k(virt);
        pte_t *ptep;

        if (pmd_none(*pmdp)) {
                ptep = alloc_bootmem_low_pages(2 * PTRS_PER_PTE *
                                               sizeof(pte_t));

                __pmd_populate(pmdp, __pa(ptep) | prot_l1);
        }
        ptep = pte_offset_kernel(pmdp, virt);

        set_pte_ext(ptep, pfn_pte(phys >> PAGE_SHIFT, prot), 0);
}

/*
 * Create the page directory entries and any necessary
 * page tables for the mapping specified by `md'.  We
 * are able to cope here with varying sizes and address
 * offsets, and we take full advantage of sections and
 * supersections.
 */
void __init create_mapping(struct map_desc *md)
{
        unsigned long virt, length;
        int prot_sect, prot_l1, domain;
        pgprot_t prot_pte;
        unsigned long off = (u32)__pfn_to_phys(md->pfn);

        if (md->virtual != vectors_base() && md->virtual < TASK_SIZE) {
                printk(KERN_WARNING "BUG: not creating mapping for "
                       "0x%08llx at 0x%08lx in user region\n",
                       __pfn_to_phys((u64)md->pfn), md->virtual);
                return;
        }

        if ((md->type == MT_DEVICE || md->type == MT_ROM) &&
            md->virtual >= PAGE_OFFSET && md->virtual < VMALLOC_END) {
                printk(KERN_WARNING "BUG: mapping for 0x%08llx at 0x%08lx "
                       "overlaps vmalloc space\n",
                       __pfn_to_phys((u64)md->pfn), md->virtual);
        }

        domain    = mem_types[md->type].domain;
        prot_pte  = __pgprot(mem_types[md->type].prot_pte);
        prot_l1   = mem_types[md->type].prot_l1 | PMD_DOMAIN(domain);
        prot_sect = mem_types[md->type].prot_sect | PMD_DOMAIN(domain);

        /*
         * Catch 36-bit addresses
         */
        if(md->pfn >= 0x100000) {
                if(domain) {
                        printk(KERN_ERR "MM: invalid domain in supersection "
                                "mapping for 0x%08llx at 0x%08lx\n",
                                __pfn_to_phys((u64)md->pfn), md->virtual);
                        return;
                }
                if((md->virtual | md->length | __pfn_to_phys(md->pfn))
                        & ~SUPERSECTION_MASK) {
                        printk(KERN_ERR "MM: cannot create mapping for "
                                "0x%08llx at 0x%08lx invalid alignment\n",
                                __pfn_to_phys((u64)md->pfn), md->virtual);
                        return;
                }

                /*
                 * Shift bits [35:32] of address into bits [23:20] of PMD
                 * (See ARMv6 spec).
                 */
                off |= (((md->pfn >> (32 - PAGE_SHIFT)) & 0xF) << 20);
        }

        virt   = md->virtual;
        off   -= virt;
        length = md->length;

        if (mem_types[md->type].prot_l1 == 0 &&
            (virt & 0xfffff || (virt + off) & 0xfffff || (virt + length) & 0xfffff)) {
                printk(KERN_WARNING "BUG: map for 0x%08lx at 0x%08lx can not "
                       "be mapped using pages, ignoring.\n",
                       __pfn_to_phys(md->pfn), md->virtual);
                return;
        }

        while ((virt & 0xfffff || (virt + off) & 0xfffff) && length >= PAGE_SIZE) {
                alloc_init_page(virt, virt + off, prot_l1, prot_pte);

                virt   += PAGE_SIZE;
                length -= PAGE_SIZE;
        }

        /* N.B. ARMv6 supersections are only defined to work with domain 0.
         *      Since domain assignments can in fact be arbitrary, the
         *      'domain == 0' check below is required to insure that ARMv6
         *      supersections are only allocated for domain 0 regardless
         *      of the actual domain assignments in use.
         */
        if ((cpu_architecture() >= CPU_ARCH_ARMv6 || cpu_is_xsc3())
                && domain == 0) {
                /*
                 * Align to supersection boundary if !high pages.
                 * High pages have already been checked for proper
                 * alignment above and they will fail the SUPSERSECTION_MASK
                 * check because of the way the address is encoded into
                 * offset.
                 */
                if (md->pfn <= 0x100000) {
                        while ((virt & ~SUPERSECTION_MASK ||
                                (virt + off) & ~SUPERSECTION_MASK) &&
                                length >= (PGDIR_SIZE / 2)) {
                                alloc_init_section(virt, virt + off, prot_sect);

                                virt   += (PGDIR_SIZE / 2);
                                length -= (PGDIR_SIZE / 2);
                        }
                }

                while (length >= SUPERSECTION_SIZE) {
                        alloc_init_supersection(virt, virt + off, prot_sect);

                        virt   += SUPERSECTION_SIZE;
                        length -= SUPERSECTION_SIZE;
                }
        }

        /*
         * A section mapping covers half a "pgdir" entry.
         */
        while (length >= (PGDIR_SIZE / 2)) {
                alloc_init_section(virt, virt + off, prot_sect);

                virt   += (PGDIR_SIZE / 2);
                length -= (PGDIR_SIZE / 2);
        }

        while (length >= PAGE_SIZE) {
                alloc_init_page(virt, virt + off, prot_l1, prot_pte);

                virt   += PAGE_SIZE;
                length -= PAGE_SIZE;
        }
}

/*
 * Create the architecture specific mappings
 */
void __init iotable_init(struct map_desc *io_desc, int nr)
{
        int i;

        for (i = 0; i < nr; i++)
                create_mapping(io_desc + i);
}

static inline void prepare_page_table(struct meminfo *mi)
{
        unsigned long addr;

        /*
         * Clear out all the mappings below the kernel image.
         */
        for (addr = 0; addr < MODULE_START; addr += PGDIR_SIZE)
                pmd_clear(pmd_off_k(addr));

#ifdef CONFIG_XIP_KERNEL
        /* The XIP kernel is mapped in the module area -- skip over it */
        addr = ((unsigned long)&_etext + PGDIR_SIZE - 1) & PGDIR_MASK;
#endif
        for ( ; addr < PAGE_OFFSET; addr += PGDIR_SIZE)
                pmd_clear(pmd_off_k(addr));

        /*
         * Clear out all the kernel space mappings, except for the first
         * memory bank, up to the end of the vmalloc region.
         */
        for (addr = __phys_to_virt(mi->bank[0].start + mi->bank[0].size);
             addr < VMALLOC_END; addr += PGDIR_SIZE)
                pmd_clear(pmd_off_k(addr));
}

/*
 * Reserve the various regions of node 0
 */
void __init reserve_node_zero(pg_data_t *pgdat)
{
        unsigned long res_size = 0;

        /*
         * Register the kernel text and data with bootmem.
         * Note that this can only be in node 0.
         */
#ifdef CONFIG_XIP_KERNEL
        reserve_bootmem_node(pgdat, __pa(&__data_start), &_end - &__data_start);
#else
        reserve_bootmem_node(pgdat, __pa(&_stext), &_end - &_stext);
#endif

        /*
         * Reserve the page tables.  These are already in use,
         * and can only be in node 0.
         */
        reserve_bootmem_node(pgdat, __pa(swapper_pg_dir),
                             PTRS_PER_PGD * sizeof(pgd_t));

        /*
         * Hmm... This should go elsewhere, but we really really need to
         * stop things allocating the low memory; ideally we need a better
         * implementation of GFP_DMA which does not assume that DMA-able
         * memory starts at zero.
         */
        if (machine_is_integrator() || machine_is_cintegrator())
                res_size = __pa(swapper_pg_dir) - PHYS_OFFSET;

        /*
         * These should likewise go elsewhere.  They pre-reserve the
         * screen memory region at the start of main system memory.
         */
        if (machine_is_edb7211())
                res_size = 0x00020000;
        if (machine_is_p720t())
                res_size = 0x00014000;

        /* H1940 and RX3715 need to reserve this for suspend */

        if (machine_is_h1940() || machine_is_rx3715()) {
                reserve_bootmem_node(pgdat, 0x30003000, 0x1000);
                reserve_bootmem_node(pgdat, 0x30081000, 0x1000);
        }

#ifdef CONFIG_SA1111
        /*
         * Because of the SA1111 DMA bug, we want to preserve our
         * precious DMA-able memory...
         */
        res_size = __pa(swapper_pg_dir) - PHYS_OFFSET;
#endif
        if (res_size)
                reserve_bootmem_node(pgdat, PHYS_OFFSET, res_size);
}

/*
 * Set up device the mappings.  Since we clear out the page tables for all
 * mappings above VMALLOC_END, we will remove any debug device mappings.
 * This means you have to be careful how you debug this function, or any
 * called function.  This means you can't use any function or debugging
 * method which may touch any device, otherwise the kernel _will_ crash.
 */
static void __init devicemaps_init(struct machine_desc *mdesc)
{
        struct map_desc map;
        unsigned long addr;
        void *vectors;

        /*
         * Allocate the vector page early.
         */
        vectors = alloc_bootmem_low_pages(PAGE_SIZE);
        BUG_ON(!vectors);

        for (addr = VMALLOC_END; addr; addr += PGDIR_SIZE)
                pmd_clear(pmd_off_k(addr));

        /*
         * Map the kernel if it is XIP.
         * It is always first in the modulearea.
         */
#ifdef CONFIG_XIP_KERNEL
        map.pfn = __phys_to_pfn(CONFIG_XIP_PHYS_ADDR & SECTION_MASK);
        map.virtual = MODULE_START;
        map.length = ((unsigned long)&_etext - map.virtual + ~SECTION_MASK) & SECTION_MASK;
        map.type = MT_ROM;
        create_mapping(&map);
#endif

        /*
         * Map the cache flushing regions.
         */
#ifdef FLUSH_BASE
        map.pfn = __phys_to_pfn(FLUSH_BASE_PHYS);
        map.virtual = FLUSH_BASE;
        map.length = SZ_1M;
        map.type = MT_CACHECLEAN;
        create_mapping(&map);
#endif
#ifdef FLUSH_BASE_MINICACHE
        map.pfn = __phys_to_pfn(FLUSH_BASE_PHYS + SZ_1M);
        map.virtual = FLUSH_BASE_MINICACHE;
        map.length = SZ_1M;
        map.type = MT_MINICLEAN;
        create_mapping(&map);
#endif

        /*
         * Create a mapping for the machine vectors at the high-vectors
         * location (0xffff0000).  If we aren't using high-vectors, also
         * create a mapping at the low-vectors virtual address.
         */
        map.pfn = __phys_to_pfn(virt_to_phys(vectors));
        map.virtual = 0xffff0000;
        map.length = PAGE_SIZE;
        map.type = MT_HIGH_VECTORS;
        create_mapping(&map);

        if (!vectors_high()) {
                map.virtual = 0;
                map.type = MT_LOW_VECTORS;
                create_mapping(&map);
        }

        /*
         * Ask the machine support to map in the statically mapped devices.
         */
        if (mdesc->map_io)
                mdesc->map_io();

        /*
         * Finally flush the caches and tlb to ensure that we're in a
         * consistent state wrt the writebuffer.  This also ensures that
         * any write-allocated cache lines in the vector page are written
         * back.  After this point, we can start to touch devices again.
         */
        local_flush_tlb_all();
        flush_cache_all();
}

/*
 * paging_init() sets up the page tables, initialises the zone memory
 * maps, and sets up the zero page, bad page and bad page tables.
 */
void __init paging_init(struct meminfo *mi, struct machine_desc *mdesc)
{
        void *zero_page;

        build_mem_type_table();
        prepare_page_table(mi);
        bootmem_init(mi);
        devicemaps_init(mdesc);

        top_pmd = pmd_off_k(0xffff0000);

        /*
         * allocate the zero page.  Note that we count on this going ok.
         */
        zero_page = alloc_bootmem_low_pages(PAGE_SIZE);
        memzero(zero_page, PAGE_SIZE);
        empty_zero_page = virt_to_page(zero_page);
        flush_dcache_page(empty_zero_page);
}

/*
 * In order to soft-boot, we need to insert a 1:1 mapping in place of
 * the user-mode pages.  This will then ensure that we have predictable
 * results when turning the mmu off
 */
void setup_mm_for_reboot(char mode)
{
        unsigned long base_pmdval;
        pgd_t *pgd;
        int i;

        if (current->mm && current->mm->pgd)
                pgd = current->mm->pgd;
        else
                pgd = init_mm.pgd;

        base_pmdval = PMD_SECT_AP_WRITE | PMD_SECT_AP_READ | PMD_TYPE_SECT;
        if (cpu_architecture() <= CPU_ARCH_ARMv5TEJ && !cpu_is_xscale())
                base_pmdval |= PMD_BIT4;

        for (i = 0; i < FIRST_USER_PGD_NR + USER_PTRS_PER_PGD; i++, pgd++) {
                unsigned long pmdval = (i << PGDIR_SHIFT) | base_pmdval;
                pmd_t *pmd;

                pmd = pmd_off(pgd, i << PGDIR_SHIFT);
                pmd[0] = __pmd(pmdval);
                pmd[1] = __pmd(pmdval + (1 << (PGDIR_SHIFT - 1)));
                flush_pmd_entry(pmd);
        }
}