Merge tag 'timers-urgent-2020-12-27' of git://git.kernel.org/pub/scm/linux/kernel...

[linux-2.6-microblaze.git] / arch / arm / mm / mmu.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 *  linux/arch/arm/mm/mmu.c
 *
 *  Copyright (C) 1995-2005 Russell King
 */
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/mman.h>
#include <linux/nodemask.h>
#include <linux/memblock.h>
#include <linux/fs.h>
#include <linux/vmalloc.h>
#include <linux/sizes.h>

#include <asm/cp15.h>
#include <asm/cputype.h>
#include <asm/cachetype.h>
#include <asm/fixmap.h>
#include <asm/sections.h>
#include <asm/setup.h>
#include <asm/smp_plat.h>
#include <asm/tlb.h>
#include <asm/highmem.h>
#include <asm/system_info.h>
#include <asm/traps.h>
#include <asm/procinfo.h>
#include <asm/memory.h>
#include <asm/pgalloc.h>
#include <asm/kasan_def.h>

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

#include "fault.h"
#include "mm.h"
#include "tcm.h"

extern unsigned long __atags_pointer;

/*
 * 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;

pmdval_t user_pmd_table = _PAGE_USER_TABLE;

#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;
        pmdval_t        pmd;
        pteval_t        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,
        }
};

#ifdef CONFIG_CPU_CP15
static unsigned long initial_pmd_value __initdata = 0;

/*
 * Initialise the cache_policy variable with the initial state specified
 * via the "pmd" value.  This is used to ensure that on ARMv6 and later,
 * the C code sets the page tables up with the same policy as the head
 * assembly code, which avoids an illegal state where the TLBs can get
 * confused.  See comments in early_cachepolicy() for more information.
 */
void __init init_default_cache_policy(unsigned long pmd)
{
        int i;

        initial_pmd_value = pmd;

        pmd &= PMD_SECT_CACHE_MASK;

        for (i = 0; i < ARRAY_SIZE(cache_policies); i++)
                if (cache_policies[i].pmd == pmd) {
                        cachepolicy = i;
                        break;
                }

        if (i == ARRAY_SIZE(cache_policies))
                pr_err("ERROR: could not find cache policy\n");
}

/*
 * 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 int __init early_cachepolicy(char *p)
{
        int i, selected = -1;

        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) {
                        selected = i;
                        break;
                }
        }

        if (selected == -1)
                pr_err("ERROR: unknown or unsupported cache policy\n");

        /*
         * This restriction is partly to do with the way we boot; it is
         * unpredictable to have memory mapped using two different sets of
         * memory attributes (shared, type, and cache attribs).  We can not
         * change these attributes once the initial assembly has setup the
         * page tables.
         */
        if (cpu_architecture() >= CPU_ARCH_ARMv6 && selected != cachepolicy) {
                pr_warn("Only cachepolicy=%s supported on ARMv6 and later\n",
                        cache_policies[cachepolicy].policy);
                return 0;
        }

        if (selected != cachepolicy) {
                unsigned long cr = __clear_cr(cache_policies[selected].cr_mask);
                cachepolicy = selected;
                flush_cache_all();
                set_cr(cr);
        }
        return 0;
}
early_param("cachepolicy", early_cachepolicy);

static int __init early_nocache(char *__unused)
{
        char *p = "buffered";
        pr_warn("nocache is deprecated; use cachepolicy=%s\n", p);
        early_cachepolicy(p);
        return 0;
}
early_param("nocache", early_nocache);

static int __init early_nowrite(char *__unused)
{
        char *p = "uncached";
        pr_warn("nowb is deprecated; use cachepolicy=%s\n", p);
        early_cachepolicy(p);
        return 0;
}
early_param("nowb", early_nowrite);

#ifndef CONFIG_ARM_LPAE
static int __init early_ecc(char *p)
{
        if (memcmp(p, "on", 2) == 0)
                ecc_mask = PMD_PROTECTION;
        else if (memcmp(p, "off", 3) == 0)
                ecc_mask = 0;
        return 0;
}
early_param("ecc", early_ecc);
#endif

#else /* ifdef CONFIG_CPU_CP15 */

static int __init early_cachepolicy(char *p)
{
        pr_warn("cachepolicy kernel parameter not supported without cp15\n");
}
early_param("cachepolicy", early_cachepolicy);

static int __init noalign_setup(char *__unused)
{
        pr_warn("noalign kernel parameter not supported without cp15\n");
}
__setup("noalign", noalign_setup);

#endif /* ifdef CONFIG_CPU_CP15 / else */

#define PROT_PTE_DEVICE         L_PTE_PRESENT|L_PTE_YOUNG|L_PTE_DIRTY|L_PTE_XN
#define PROT_PTE_S2_DEVICE      PROT_PTE_DEVICE
#define PROT_SECT_DEVICE        PMD_TYPE_SECT|PMD_SECT_AP_WRITE

static struct mem_type mem_types[] __ro_after_init = {
        [MT_DEVICE] = {           /* Strongly ordered / ARMv6 shared device */
                .prot_pte       = PROT_PTE_DEVICE | L_PTE_MT_DEV_SHARED |
                                  L_PTE_SHARED,
                .prot_l1        = PMD_TYPE_TABLE,
                .prot_sect      = PROT_SECT_DEVICE | PMD_SECT_S,
                .domain         = DOMAIN_IO,
        },
        [MT_DEVICE_NONSHARED] = { /* ARMv6 non-shared device */
                .prot_pte       = PROT_PTE_DEVICE | L_PTE_MT_DEV_NONSHARED,
                .prot_l1        = PMD_TYPE_TABLE,
                .prot_sect      = PROT_SECT_DEVICE,
                .domain         = DOMAIN_IO,
        },
        [MT_DEVICE_CACHED] = {    /* ioremap_cache */
                .prot_pte       = PROT_PTE_DEVICE | L_PTE_MT_DEV_CACHED,
                .prot_l1        = PMD_TYPE_TABLE,
                .prot_sect      = PROT_SECT_DEVICE | PMD_SECT_WB,
                .domain         = DOMAIN_IO,
        },
        [MT_DEVICE_WC] = {      /* ioremap_wc */
                .prot_pte       = PROT_PTE_DEVICE | L_PTE_MT_DEV_WC,
                .prot_l1        = PMD_TYPE_TABLE,
                .prot_sect      = PROT_SECT_DEVICE,
                .domain         = DOMAIN_IO,
        },
        [MT_UNCACHED] = {
                .prot_pte       = PROT_PTE_DEVICE,
                .prot_l1        = PMD_TYPE_TABLE,
                .prot_sect      = PMD_TYPE_SECT | PMD_SECT_XN,
                .domain         = DOMAIN_IO,
        },
        [MT_CACHECLEAN] = {
                .prot_sect = PMD_TYPE_SECT | PMD_SECT_XN,
                .domain    = DOMAIN_KERNEL,
        },
#ifndef CONFIG_ARM_LPAE
        [MT_MINICLEAN] = {
                .prot_sect = PMD_TYPE_SECT | PMD_SECT_XN | PMD_SECT_MINICACHE,
                .domain    = DOMAIN_KERNEL,
        },
#endif
        [MT_LOW_VECTORS] = {
                .prot_pte  = L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY |
                                L_PTE_RDONLY,
                .prot_l1   = PMD_TYPE_TABLE,
                .domain    = DOMAIN_VECTORS,
        },
        [MT_HIGH_VECTORS] = {
                .prot_pte  = L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY |
                                L_PTE_USER | L_PTE_RDONLY,
                .prot_l1   = PMD_TYPE_TABLE,
                .domain    = DOMAIN_VECTORS,
        },
        [MT_MEMORY_RWX] = {
                .prot_pte  = L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY,
                .prot_l1   = PMD_TYPE_TABLE,
                .prot_sect = PMD_TYPE_SECT | PMD_SECT_AP_WRITE,
                .domain    = DOMAIN_KERNEL,
        },
        [MT_MEMORY_RW] = {
                .prot_pte  = L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY |
                             L_PTE_XN,
                .prot_l1   = PMD_TYPE_TABLE,
                .prot_sect = PMD_TYPE_SECT | PMD_SECT_AP_WRITE,
                .domain    = DOMAIN_KERNEL,
        },
        [MT_ROM] = {
                .prot_sect = PMD_TYPE_SECT,
                .domain    = DOMAIN_KERNEL,
        },
        [MT_MEMORY_RWX_NONCACHED] = {
                .prot_pte  = L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY |
                                L_PTE_MT_BUFFERABLE,
                .prot_l1   = PMD_TYPE_TABLE,
                .prot_sect = PMD_TYPE_SECT | PMD_SECT_AP_WRITE,
                .domain    = DOMAIN_KERNEL,
        },
        [MT_MEMORY_RW_DTCM] = {
                .prot_pte  = L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY |
                                L_PTE_XN,
                .prot_l1   = PMD_TYPE_TABLE,
                .prot_sect = PMD_TYPE_SECT | PMD_SECT_XN,
                .domain    = DOMAIN_KERNEL,
        },
        [MT_MEMORY_RWX_ITCM] = {
                .prot_pte  = L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY,
                .prot_l1   = PMD_TYPE_TABLE,
                .domain    = DOMAIN_KERNEL,
        },
        [MT_MEMORY_RW_SO] = {
                .prot_pte  = L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY |
                                L_PTE_MT_UNCACHED | L_PTE_XN,
                .prot_l1   = PMD_TYPE_TABLE,
                .prot_sect = PMD_TYPE_SECT | PMD_SECT_AP_WRITE | PMD_SECT_S |
                                PMD_SECT_UNCACHED | PMD_SECT_XN,
                .domain    = DOMAIN_KERNEL,
        },
        [MT_MEMORY_DMA_READY] = {
                .prot_pte  = L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY |
                                L_PTE_XN,
                .prot_l1   = PMD_TYPE_TABLE,
                .domain    = DOMAIN_KERNEL,
        },
};

const struct mem_type *get_mem_type(unsigned int type)
{
        return type < ARRAY_SIZE(mem_types) ? &mem_types[type] : NULL;
}
EXPORT_SYMBOL(get_mem_type);

static pte_t *(*pte_offset_fixmap)(pmd_t *dir, unsigned long addr);

static pte_t bm_pte[PTRS_PER_PTE + PTE_HWTABLE_PTRS]
        __aligned(PTE_HWTABLE_OFF + PTE_HWTABLE_SIZE) __initdata;

static pte_t * __init pte_offset_early_fixmap(pmd_t *dir, unsigned long addr)
{
        return &bm_pte[pte_index(addr)];
}

static pte_t *pte_offset_late_fixmap(pmd_t *dir, unsigned long addr)
{
        return pte_offset_kernel(dir, addr);
}

static inline pmd_t * __init fixmap_pmd(unsigned long addr)
{
        return pmd_off_k(addr);
}

void __init early_fixmap_init(void)
{
        pmd_t *pmd;

        /*
         * The early fixmap range spans multiple pmds, for which
         * we are not prepared:
         */
        BUILD_BUG_ON((__fix_to_virt(__end_of_early_ioremap_region) >> PMD_SHIFT)
                     != FIXADDR_TOP >> PMD_SHIFT);

        pmd = fixmap_pmd(FIXADDR_TOP);
        pmd_populate_kernel(&init_mm, pmd, bm_pte);

        pte_offset_fixmap = pte_offset_early_fixmap;
}

/*
 * To avoid TLB flush broadcasts, this uses local_flush_tlb_kernel_range().
 * As a result, this can only be called with preemption disabled, as under
 * stop_machine().
 */
void __set_fixmap(enum fixed_addresses idx, phys_addr_t phys, pgprot_t prot)
{
        unsigned long vaddr = __fix_to_virt(idx);
        pte_t *pte = pte_offset_fixmap(pmd_off_k(vaddr), vaddr);

        /* Make sure fixmap region does not exceed available allocation. */
        BUILD_BUG_ON(FIXADDR_START + (__end_of_fixed_addresses * PAGE_SIZE) >
                     FIXADDR_END);
        BUG_ON(idx >= __end_of_fixed_addresses);

        /* we only support device mappings until pgprot_kernel has been set */
        if (WARN_ON(pgprot_val(prot) != pgprot_val(FIXMAP_PAGE_IO) &&
                    pgprot_val(pgprot_kernel) == 0))
                return;

        if (pgprot_val(prot))
                set_pte_at(NULL, vaddr, pte,
                        pfn_pte(phys >> PAGE_SHIFT, prot));
        else
                pte_clear(NULL, vaddr, pte);
        local_flush_tlb_kernel_range(vaddr, vaddr + PAGE_SIZE);
}

/*
 * 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();
        pteval_t user_pgprot, kern_pgprot, vecs_pgprot;
        int cpu_arch = cpu_architecture();
        int i;

        if (cpu_arch < CPU_ARCH_ARMv6) {
#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;
        }

        if (is_smp()) {
                if (cachepolicy != CPOLICY_WRITEALLOC) {
                        pr_warn("Forcing write-allocate cache policy for SMP\n");
                        cachepolicy = CPOLICY_WRITEALLOC;
                }
                if (!(initial_pmd_value & PMD_SECT_S)) {
                        pr_warn("Forcing shared mappings for SMP\n");
                        initial_pmd_value |= PMD_SECT_S;
                }
        }

        /*
         * Strip out features not present on earlier architectures.
         * Pre-ARMv5 CPUs don't have TEX bits.  Pre-ARMv6 CPUs or those
         * without extended page tables don't have the 'Shared' bit.
         */
        if (cpu_arch < CPU_ARCH_ARMv5)
                for (i = 0; i < ARRAY_SIZE(mem_types); i++)
                        mem_types[i].prot_sect &= ~PMD_SECT_TEX(7);
        if ((cpu_arch < CPU_ARCH_ARMv6 || !(cr & CR_XP)) && !cpu_is_xsc3())
                for (i = 0; i < ARRAY_SIZE(mem_types); i++)
                        mem_types[i].prot_sect &= ~PMD_SECT_S;

        /*
         * ARMv5 and lower, bit 4 must be set for page tables (was: cache
         * "update-able on write" bit on ARM610).  However, Xscale and
         * Xscale3 require this bit to be cleared.
         */
        if (cpu_is_xscale_family()) {
                for (i = 0; i < ARRAY_SIZE(mem_types); i++) {
                        mem_types[i].prot_sect &= ~PMD_BIT4;
                        mem_types[i].prot_l1 &= ~PMD_BIT4;
                }
        } else if (cpu_arch < CPU_ARCH_ARMv6) {
                for (i = 0; i < ARRAY_SIZE(mem_types); i++) {
                        if (mem_types[i].prot_l1)
                                mem_types[i].prot_l1 |= PMD_BIT4;
                        if (mem_types[i].prot_sect)
                                mem_types[i].prot_sect |= PMD_BIT4;
                }
        }

        /*
         * Mark the device areas according to the CPU/architecture.
         */
        if (cpu_is_xsc3() || (cpu_arch >= CPU_ARCH_ARMv6 && (cr & CR_XP))) {
                if (!cpu_is_xsc3()) {
                        /*
                         * Mark device regions on ARMv6+ as execute-never
                         * to prevent speculative instruction fetches.
                         */
                        mem_types[MT_DEVICE].prot_sect |= PMD_SECT_XN;
                        mem_types[MT_DEVICE_NONSHARED].prot_sect |= PMD_SECT_XN;
                        mem_types[MT_DEVICE_CACHED].prot_sect |= PMD_SECT_XN;
                        mem_types[MT_DEVICE_WC].prot_sect |= PMD_SECT_XN;

                        /* Also setup NX memory mapping */
                        mem_types[MT_MEMORY_RW].prot_sect |= PMD_SECT_XN;
                }
                if (cpu_arch >= CPU_ARCH_ARMv7 && (cr & CR_TRE)) {
                        /*
                         * For ARMv7 with TEX remapping,
                         * - shared device is SXCB=1100
                         * - nonshared device is SXCB=0100
                         * - write combine device mem is SXCB=0001
                         * (Uncached Normal memory)
                         */
                        mem_types[MT_DEVICE].prot_sect |= PMD_SECT_TEX(1);
                        mem_types[MT_DEVICE_NONSHARED].prot_sect |= PMD_SECT_TEX(1);
                        mem_types[MT_DEVICE_WC].prot_sect |= PMD_SECT_BUFFERABLE;
                } else if (cpu_is_xsc3()) {
                        /*
                         * For Xscale3,
                         * - shared device is TEXCB=00101
                         * - nonshared device is TEXCB=01000
                         * - write combine device mem is TEXCB=00100
                         * (Inner/Outer Uncacheable in xsc3 parlance)
                         */
                        mem_types[MT_DEVICE].prot_sect |= PMD_SECT_TEX(1) | PMD_SECT_BUFFERED;
                        mem_types[MT_DEVICE_NONSHARED].prot_sect |= PMD_SECT_TEX(2);
                        mem_types[MT_DEVICE_WC].prot_sect |= PMD_SECT_TEX(1);
                } else {
                        /*
                         * For ARMv6 and ARMv7 without TEX remapping,
                         * - shared device is TEXCB=00001
                         * - nonshared device is TEXCB=01000
                         * - write combine device mem is TEXCB=00100
                         * (Uncached Normal in ARMv6 parlance).
                         */
                        mem_types[MT_DEVICE].prot_sect |= PMD_SECT_BUFFERED;
                        mem_types[MT_DEVICE_NONSHARED].prot_sect |= PMD_SECT_TEX(2);
                        mem_types[MT_DEVICE_WC].prot_sect |= PMD_SECT_TEX(1);
                }
        } else {
                /*
                 * On others, write combining is "Uncached/Buffered"
                 */
                mem_types[MT_DEVICE_WC].prot_sect |= PMD_SECT_BUFFERABLE;
        }

        /*
         * Now deal with the memory-type mappings
         */
        cp = &cache_policies[cachepolicy];
        vecs_pgprot = kern_pgprot = user_pgprot = cp->pte;

#ifndef CONFIG_ARM_LPAE
        /*
         * We don't use domains on ARMv6 (since this causes problems with
         * v6/v7 kernels), so we must use a separate memory type for user
         * r/o, kernel r/w to map the vectors page.
         */
        if (cpu_arch == CPU_ARCH_ARMv6)
                vecs_pgprot |= L_PTE_MT_VECTORS;

        /*
         * Check is it with support for the PXN bit
         * in the Short-descriptor translation table format descriptors.
         */
        if (cpu_arch == CPU_ARCH_ARMv7 &&
                (read_cpuid_ext(CPUID_EXT_MMFR0) & 0xF) >= 4) {
                user_pmd_table |= PMD_PXNTABLE;
        }
#endif

        /*
         * ARMv6 and above have extended page tables.
         */
        if (cpu_arch >= CPU_ARCH_ARMv6 && (cr & CR_XP)) {
#ifndef CONFIG_ARM_LPAE
                /*
                 * 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;
#endif

                /*
                 * If the initial page tables were created with the S bit
                 * set, then we need to do the same here for the same
                 * reasons given in early_cachepolicy().
                 */
                if (initial_pmd_value & PMD_SECT_S) {
                        user_pgprot |= L_PTE_SHARED;
                        kern_pgprot |= L_PTE_SHARED;
                        vecs_pgprot |= L_PTE_SHARED;
                        mem_types[MT_DEVICE_WC].prot_sect |= PMD_SECT_S;
                        mem_types[MT_DEVICE_WC].prot_pte |= L_PTE_SHARED;
                        mem_types[MT_DEVICE_CACHED].prot_sect |= PMD_SECT_S;
                        mem_types[MT_DEVICE_CACHED].prot_pte |= L_PTE_SHARED;
                        mem_types[MT_MEMORY_RWX].prot_sect |= PMD_SECT_S;
                        mem_types[MT_MEMORY_RWX].prot_pte |= L_PTE_SHARED;
                        mem_types[MT_MEMORY_RW].prot_sect |= PMD_SECT_S;
                        mem_types[MT_MEMORY_RW].prot_pte |= L_PTE_SHARED;
                        mem_types[MT_MEMORY_DMA_READY].prot_pte |= L_PTE_SHARED;
                        mem_types[MT_MEMORY_RWX_NONCACHED].prot_sect |= PMD_SECT_S;
                        mem_types[MT_MEMORY_RWX_NONCACHED].prot_pte |= L_PTE_SHARED;
                }
        }

        /*
         * Non-cacheable Normal - intended for memory areas that must
         * not cause dirty cache line writebacks when used
         */
        if (cpu_arch >= CPU_ARCH_ARMv6) {
                if (cpu_arch >= CPU_ARCH_ARMv7 && (cr & CR_TRE)) {
                        /* Non-cacheable Normal is XCB = 001 */
                        mem_types[MT_MEMORY_RWX_NONCACHED].prot_sect |=
                                PMD_SECT_BUFFERED;
                } else {
                        /* For both ARMv6 and non-TEX-remapping ARMv7 */
                        mem_types[MT_MEMORY_RWX_NONCACHED].prot_sect |=
                                PMD_SECT_TEX(1);
                }
        } else {
                mem_types[MT_MEMORY_RWX_NONCACHED].prot_sect |= PMD_SECT_BUFFERABLE;
        }

#ifdef CONFIG_ARM_LPAE
        /*
         * Do not generate access flag faults for the kernel mappings.
         */
        for (i = 0; i < ARRAY_SIZE(mem_types); i++) {
                mem_types[i].prot_pte |= PTE_EXT_AF;
                if (mem_types[i].prot_sect)
                        mem_types[i].prot_sect |= PMD_SECT_AF;
        }
        kern_pgprot |= PTE_EXT_AF;
        vecs_pgprot |= PTE_EXT_AF;

        /*
         * Set PXN for user mappings
         */
        user_pgprot |= PTE_EXT_PXN;
#endif

        for (i = 0; i < 16; i++) {
                pteval_t v = pgprot_val(protection_map[i]);
                protection_map[i] = __pgprot(v | user_pgprot);
        }

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

        pgprot_user   = __pgprot(L_PTE_PRESENT | L_PTE_YOUNG | user_pgprot);
        pgprot_kernel = __pgprot(L_PTE_PRESENT | L_PTE_YOUNG |
                                 L_PTE_DIRTY | kern_pgprot);

        mem_types[MT_LOW_VECTORS].prot_l1 |= ecc_mask;
        mem_types[MT_HIGH_VECTORS].prot_l1 |= ecc_mask;
        mem_types[MT_MEMORY_RWX].prot_sect |= ecc_mask | cp->pmd;
        mem_types[MT_MEMORY_RWX].prot_pte |= kern_pgprot;
        mem_types[MT_MEMORY_RW].prot_sect |= ecc_mask | cp->pmd;
        mem_types[MT_MEMORY_RW].prot_pte |= kern_pgprot;
        mem_types[MT_MEMORY_DMA_READY].prot_pte |= kern_pgprot;
        mem_types[MT_MEMORY_RWX_NONCACHED].prot_sect |= ecc_mask;
        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;
        }
        pr_info("Memory policy: %sData cache %s\n",
                ecc_mask ? "ECC enabled, " : "", cp->policy);

        for (i = 0; i < ARRAY_SIZE(mem_types); i++) {
                struct mem_type *t = &mem_types[i];
                if (t->prot_l1)
                        t->prot_l1 |= PMD_DOMAIN(t->domain);
                if (t->prot_sect)
                        t->prot_sect |= PMD_DOMAIN(t->domain);
        }
}

#ifdef CONFIG_ARM_DMA_MEM_BUFFERABLE
pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
                              unsigned long size, pgprot_t vma_prot)
{
        if (!pfn_valid(pfn))
                return pgprot_noncached(vma_prot);
        else if (file->f_flags & O_SYNC)
                return pgprot_writecombine(vma_prot);
        return vma_prot;
}
EXPORT_SYMBOL(phys_mem_access_prot);
#endif

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

static void __init *early_alloc(unsigned long sz)
{
        void *ptr = memblock_alloc(sz, sz);

        if (!ptr)
                panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
                      __func__, sz, sz);

        return ptr;
}

static void *__init late_alloc(unsigned long sz)
{
        void *ptr = (void *)__get_free_pages(GFP_PGTABLE_KERNEL, get_order(sz));

        if (!ptr || !pgtable_pte_page_ctor(virt_to_page(ptr)))
                BUG();
        return ptr;
}

static pte_t * __init arm_pte_alloc(pmd_t *pmd, unsigned long addr,
                                unsigned long prot,
                                void *(*alloc)(unsigned long sz))
{
        if (pmd_none(*pmd)) {
                pte_t *pte = alloc(PTE_HWTABLE_OFF + PTE_HWTABLE_SIZE);
                __pmd_populate(pmd, __pa(pte), prot);
        }
        BUG_ON(pmd_bad(*pmd));
        return pte_offset_kernel(pmd, addr);
}

static pte_t * __init early_pte_alloc(pmd_t *pmd, unsigned long addr,
                                      unsigned long prot)
{
        return arm_pte_alloc(pmd, addr, prot, early_alloc);
}

static void __init alloc_init_pte(pmd_t *pmd, unsigned long addr,
                                  unsigned long end, unsigned long pfn,
                                  const struct mem_type *type,
                                  void *(*alloc)(unsigned long sz),
                                  bool ng)
{
        pte_t *pte = arm_pte_alloc(pmd, addr, type->prot_l1, alloc);
        do {
                set_pte_ext(pte, pfn_pte(pfn, __pgprot(type->prot_pte)),
                            ng ? PTE_EXT_NG : 0);
                pfn++;
        } while (pte++, addr += PAGE_SIZE, addr != end);
}

static void __init __map_init_section(pmd_t *pmd, unsigned long addr,
                        unsigned long end, phys_addr_t phys,
                        const struct mem_type *type, bool ng)
{
        pmd_t *p = pmd;

#ifndef CONFIG_ARM_LPAE
        /*
         * In classic MMU format, puds and pmds are folded in to
         * the pgds. pmd_offset gives the PGD entry. PGDs refer to a
         * group of L1 entries making up one logical pointer to
         * an L2 table (2MB), where as PMDs refer to the individual
         * L1 entries (1MB). Hence increment to get the correct
         * offset for odd 1MB sections.
         * (See arch/arm/include/asm/pgtable-2level.h)
         */
        if (addr & SECTION_SIZE)
                pmd++;
#endif
        do {
                *pmd = __pmd(phys | type->prot_sect | (ng ? PMD_SECT_nG : 0));
                phys += SECTION_SIZE;
        } while (pmd++, addr += SECTION_SIZE, addr != end);

        flush_pmd_entry(p);
}

static void __init alloc_init_pmd(pud_t *pud, unsigned long addr,
                                      unsigned long end, phys_addr_t phys,
                                      const struct mem_type *type,
                                      void *(*alloc)(unsigned long sz), bool ng)
{
        pmd_t *pmd = pmd_offset(pud, addr);
        unsigned long next;

        do {
                /*
                 * With LPAE, we must loop over to map
                 * all the pmds for the given range.
                 */
                next = pmd_addr_end(addr, end);

                /*
                 * Try a section mapping - addr, next and phys must all be
                 * aligned to a section boundary.
                 */
                if (type->prot_sect &&
                                ((addr | next | phys) & ~SECTION_MASK) == 0) {
                        __map_init_section(pmd, addr, next, phys, type, ng);
                } else {
                        alloc_init_pte(pmd, addr, next,
                                       __phys_to_pfn(phys), type, alloc, ng);
                }

                phys += next - addr;

        } while (pmd++, addr = next, addr != end);
}

static void __init alloc_init_pud(p4d_t *p4d, unsigned long addr,
                                  unsigned long end, phys_addr_t phys,
                                  const struct mem_type *type,
                                  void *(*alloc)(unsigned long sz), bool ng)
{
        pud_t *pud = pud_offset(p4d, addr);
        unsigned long next;

        do {
                next = pud_addr_end(addr, end);
                alloc_init_pmd(pud, addr, next, phys, type, alloc, ng);
                phys += next - addr;
        } while (pud++, addr = next, addr != end);
}

static void __init alloc_init_p4d(pgd_t *pgd, unsigned long addr,
                                  unsigned long end, phys_addr_t phys,
                                  const struct mem_type *type,
                                  void *(*alloc)(unsigned long sz), bool ng)
{
        p4d_t *p4d = p4d_offset(pgd, addr);
        unsigned long next;

        do {
                next = p4d_addr_end(addr, end);
                alloc_init_pud(p4d, addr, next, phys, type, alloc, ng);
                phys += next - addr;
        } while (p4d++, addr = next, addr != end);
}

#ifndef CONFIG_ARM_LPAE
static void __init create_36bit_mapping(struct mm_struct *mm,
                                        struct map_desc *md,
                                        const struct mem_type *type,
                                        bool ng)
{
        unsigned long addr, length, end;
        phys_addr_t phys;
        pgd_t *pgd;

        addr = md->virtual;
        phys = __pfn_to_phys(md->pfn);
        length = PAGE_ALIGN(md->length);

        if (!(cpu_architecture() >= CPU_ARCH_ARMv6 || cpu_is_xsc3())) {
                pr_err("MM: CPU does not support supersection mapping for 0x%08llx at 0x%08lx\n",
                       (long long)__pfn_to_phys((u64)md->pfn), addr);
                return;
        }

        /* 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 (type->domain) {
                pr_err("MM: invalid domain in supersection mapping for 0x%08llx at 0x%08lx\n",
                       (long long)__pfn_to_phys((u64)md->pfn), addr);
                return;
        }

        if ((addr | length | __pfn_to_phys(md->pfn)) & ~SUPERSECTION_MASK) {
                pr_err("MM: cannot create mapping for 0x%08llx at 0x%08lx invalid alignment\n",
                       (long long)__pfn_to_phys((u64)md->pfn), addr);
                return;
        }

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

        pgd = pgd_offset(mm, addr);
        end = addr + length;
        do {
                p4d_t *p4d = p4d_offset(pgd, addr);
                pud_t *pud = pud_offset(p4d, addr);
                pmd_t *pmd = pmd_offset(pud, addr);
                int i;

                for (i = 0; i < 16; i++)
                        *pmd++ = __pmd(phys | type->prot_sect | PMD_SECT_SUPER |
                                       (ng ? PMD_SECT_nG : 0));

                addr += SUPERSECTION_SIZE;
                phys += SUPERSECTION_SIZE;
                pgd += SUPERSECTION_SIZE >> PGDIR_SHIFT;
        } while (addr != end);
}
#endif  /* !CONFIG_ARM_LPAE */

static void __init __create_mapping(struct mm_struct *mm, struct map_desc *md,
                                    void *(*alloc)(unsigned long sz),
                                    bool ng)
{
        unsigned long addr, length, end;
        phys_addr_t phys;
        const struct mem_type *type;
        pgd_t *pgd;

        type = &mem_types[md->type];

#ifndef CONFIG_ARM_LPAE
        /*
         * Catch 36-bit addresses
         */
        if (md->pfn >= 0x100000) {
                create_36bit_mapping(mm, md, type, ng);
                return;
        }
#endif

        addr = md->virtual & PAGE_MASK;
        phys = __pfn_to_phys(md->pfn);
        length = PAGE_ALIGN(md->length + (md->virtual & ~PAGE_MASK));

        if (type->prot_l1 == 0 && ((addr | phys | length) & ~SECTION_MASK)) {
                pr_warn("BUG: map for 0x%08llx at 0x%08lx can not be mapped using pages, ignoring.\n",
                        (long long)__pfn_to_phys(md->pfn), addr);
                return;
        }

        pgd = pgd_offset(mm, addr);
        end = addr + length;
        do {
                unsigned long next = pgd_addr_end(addr, end);

                alloc_init_p4d(pgd, addr, next, phys, type, alloc, ng);

                phys += next - addr;
                addr = next;
        } while (pgd++, addr != end);
}

/*
 * 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.
 */
static void __init create_mapping(struct map_desc *md)
{
        if (md->virtual != vectors_base() && md->virtual < TASK_SIZE) {
                pr_warn("BUG: not creating mapping for 0x%08llx at 0x%08lx in user region\n",
                        (long long)__pfn_to_phys((u64)md->pfn), md->virtual);
                return;
        }

        if (md->type == MT_DEVICE &&
            md->virtual >= PAGE_OFFSET && md->virtual < FIXADDR_START &&
            (md->virtual < VMALLOC_START || md->virtual >= VMALLOC_END)) {
                pr_warn("BUG: mapping for 0x%08llx at 0x%08lx out of vmalloc space\n",
                        (long long)__pfn_to_phys((u64)md->pfn), md->virtual);
        }

        __create_mapping(&init_mm, md, early_alloc, false);
}

void __init create_mapping_late(struct mm_struct *mm, struct map_desc *md,
                                bool ng)
{
#ifdef CONFIG_ARM_LPAE
        p4d_t *p4d;
        pud_t *pud;

        p4d = p4d_alloc(mm, pgd_offset(mm, md->virtual), md->virtual);
        if (WARN_ON(!p4d))
                return;
        pud = pud_alloc(mm, p4d, md->virtual);
        if (WARN_ON(!pud))
                return;
        pmd_alloc(mm, pud, 0);
#endif
        __create_mapping(mm, md, late_alloc, ng);
}

/*
 * Create the architecture specific mappings
 */
void __init iotable_init(struct map_desc *io_desc, int nr)
{
        struct map_desc *md;
        struct vm_struct *vm;
        struct static_vm *svm;

        if (!nr)
                return;

        svm = memblock_alloc(sizeof(*svm) * nr, __alignof__(*svm));
        if (!svm)
                panic("%s: Failed to allocate %zu bytes align=0x%zx\n",
                      __func__, sizeof(*svm) * nr, __alignof__(*svm));

        for (md = io_desc; nr; md++, nr--) {
                create_mapping(md);

                vm = &svm->vm;
                vm->addr = (void *)(md->virtual & PAGE_MASK);
                vm->size = PAGE_ALIGN(md->length + (md->virtual & ~PAGE_MASK));
                vm->phys_addr = __pfn_to_phys(md->pfn);
                vm->flags = VM_IOREMAP | VM_ARM_STATIC_MAPPING;
                vm->flags |= VM_ARM_MTYPE(md->type);
                vm->caller = iotable_init;
                add_static_vm_early(svm++);
        }
}

void __init vm_reserve_area_early(unsigned long addr, unsigned long size,
                                  void *caller)
{
        struct vm_struct *vm;
        struct static_vm *svm;

        svm = memblock_alloc(sizeof(*svm), __alignof__(*svm));
        if (!svm)
                panic("%s: Failed to allocate %zu bytes align=0x%zx\n",
                      __func__, sizeof(*svm), __alignof__(*svm));

        vm = &svm->vm;
        vm->addr = (void *)addr;
        vm->size = size;
        vm->flags = VM_IOREMAP | VM_ARM_EMPTY_MAPPING;
        vm->caller = caller;
        add_static_vm_early(svm);
}

#ifndef CONFIG_ARM_LPAE

/*
 * The Linux PMD is made of two consecutive section entries covering 2MB
 * (see definition in include/asm/pgtable-2level.h).  However a call to
 * create_mapping() may optimize static mappings by using individual
 * 1MB section mappings.  This leaves the actual PMD potentially half
 * initialized if the top or bottom section entry isn't used, leaving it
 * open to problems if a subsequent ioremap() or vmalloc() tries to use
 * the virtual space left free by that unused section entry.
 *
 * Let's avoid the issue by inserting dummy vm entries covering the unused
 * PMD halves once the static mappings are in place.
 */

static void __init pmd_empty_section_gap(unsigned long addr)
{
        vm_reserve_area_early(addr, SECTION_SIZE, pmd_empty_section_gap);
}

static void __init fill_pmd_gaps(void)
{
        struct static_vm *svm;
        struct vm_struct *vm;
        unsigned long addr, next = 0;
        pmd_t *pmd;

        list_for_each_entry(svm, &static_vmlist, list) {
                vm = &svm->vm;
                addr = (unsigned long)vm->addr;
                if (addr < next)
                        continue;

                /*
                 * Check if this vm starts on an odd section boundary.
                 * If so and the first section entry for this PMD is free
                 * then we block the corresponding virtual address.
                 */
                if ((addr & ~PMD_MASK) == SECTION_SIZE) {
                        pmd = pmd_off_k(addr);
                        if (pmd_none(*pmd))
                                pmd_empty_section_gap(addr & PMD_MASK);
                }

                /*
                 * Then check if this vm ends on an odd section boundary.
                 * If so and the second section entry for this PMD is empty
                 * then we block the corresponding virtual address.
                 */
                addr += vm->size;
                if ((addr & ~PMD_MASK) == SECTION_SIZE) {
                        pmd = pmd_off_k(addr) + 1;
                        if (pmd_none(*pmd))
                                pmd_empty_section_gap(addr);
                }

                /* no need to look at any vm entry until we hit the next PMD */
                next = (addr + PMD_SIZE - 1) & PMD_MASK;
        }
}

#else
#define fill_pmd_gaps() do { } while (0)
#endif

#if defined(CONFIG_PCI) && !defined(CONFIG_NEED_MACH_IO_H)
static void __init pci_reserve_io(void)
{
        struct static_vm *svm;

        svm = find_static_vm_vaddr((void *)PCI_IO_VIRT_BASE);
        if (svm)
                return;

        vm_reserve_area_early(PCI_IO_VIRT_BASE, SZ_2M, pci_reserve_io);
}
#else
#define pci_reserve_io() do { } while (0)
#endif

#ifdef CONFIG_DEBUG_LL
void __init debug_ll_io_init(void)
{
        struct map_desc map;

        debug_ll_addr(&map.pfn, &map.virtual);
        if (!map.pfn || !map.virtual)
                return;
        map.pfn = __phys_to_pfn(map.pfn);
        map.virtual &= PAGE_MASK;
        map.length = PAGE_SIZE;
        map.type = MT_DEVICE;
        iotable_init(&map, 1);
}
#endif

static void * __initdata vmalloc_min =
        (void *)(VMALLOC_END - (240 << 20) - VMALLOC_OFFSET);

/*
 * vmalloc=size forces the vmalloc area to be exactly 'size'
 * bytes. This can be used to increase (or decrease) the vmalloc
 * area - the default is 240m.
 */
static int __init early_vmalloc(char *arg)
{
        unsigned long vmalloc_reserve = memparse(arg, NULL);

        if (vmalloc_reserve < SZ_16M) {
                vmalloc_reserve = SZ_16M;
                pr_warn("vmalloc area too small, limiting to %luMB\n",
                        vmalloc_reserve >> 20);
        }

        if (vmalloc_reserve > VMALLOC_END - (PAGE_OFFSET + SZ_32M)) {
                vmalloc_reserve = VMALLOC_END - (PAGE_OFFSET + SZ_32M);
                pr_warn("vmalloc area is too big, limiting to %luMB\n",
                        vmalloc_reserve >> 20);
        }

        vmalloc_min = (void *)(VMALLOC_END - vmalloc_reserve);
        return 0;
}
early_param("vmalloc", early_vmalloc);

phys_addr_t arm_lowmem_limit __initdata = 0;

void __init adjust_lowmem_bounds(void)
{
        phys_addr_t block_start, block_end, memblock_limit = 0;
        u64 vmalloc_limit, i;
        phys_addr_t lowmem_limit = 0;

        /*
         * Let's use our own (unoptimized) equivalent of __pa() that is
         * not affected by wrap-arounds when sizeof(phys_addr_t) == 4.
         * The result is used as the upper bound on physical memory address
         * and may itself be outside the valid range for which phys_addr_t
         * and therefore __pa() is defined.
         */
        vmalloc_limit = (u64)(uintptr_t)vmalloc_min - PAGE_OFFSET + PHYS_OFFSET;

        /*
         * The first usable region must be PMD aligned. Mark its start
         * as MEMBLOCK_NOMAP if it isn't
         */
        for_each_mem_range(i, &block_start, &block_end) {
                if (!IS_ALIGNED(block_start, PMD_SIZE)) {
                        phys_addr_t len;

                        len = round_up(block_start, PMD_SIZE) - block_start;
                        memblock_mark_nomap(block_start, len);
                }
                break;
        }

        for_each_mem_range(i, &block_start, &block_end) {
                if (block_start < vmalloc_limit) {
                        if (block_end > lowmem_limit)
                                /*
                                 * Compare as u64 to ensure vmalloc_limit does
                                 * not get truncated. block_end should always
                                 * fit in phys_addr_t so there should be no
                                 * issue with assignment.
                                 */
                                lowmem_limit = min_t(u64,
                                                         vmalloc_limit,
                                                         block_end);

                        /*
                         * Find the first non-pmd-aligned page, and point
                         * memblock_limit at it. This relies on rounding the
                         * limit down to be pmd-aligned, which happens at the
                         * end of this function.
                         *
                         * With this algorithm, the start or end of almost any
                         * bank can be non-pmd-aligned. The only exception is
                         * that the start of the bank 0 must be section-
                         * aligned, since otherwise memory would need to be
                         * allocated when mapping the start of bank 0, which
                         * occurs before any free memory is mapped.
                         */
                        if (!memblock_limit) {
                                if (!IS_ALIGNED(block_start, PMD_SIZE))
                                        memblock_limit = block_start;
                                else if (!IS_ALIGNED(block_end, PMD_SIZE))
                                        memblock_limit = lowmem_limit;
                        }

                }
        }

        arm_lowmem_limit = lowmem_limit;

        high_memory = __va(arm_lowmem_limit - 1) + 1;

        if (!memblock_limit)
                memblock_limit = arm_lowmem_limit;

        /*
         * Round the memblock limit down to a pmd size.  This
         * helps to ensure that we will allocate memory from the
         * last full pmd, which should be mapped.
         */
        memblock_limit = round_down(memblock_limit, PMD_SIZE);

        if (!IS_ENABLED(CONFIG_HIGHMEM) || cache_is_vipt_aliasing()) {
                if (memblock_end_of_DRAM() > arm_lowmem_limit) {
                        phys_addr_t end = memblock_end_of_DRAM();

                        pr_notice("Ignoring RAM at %pa-%pa\n",
                                  &memblock_limit, &end);
                        pr_notice("Consider using a HIGHMEM enabled kernel.\n");

                        memblock_remove(memblock_limit, end - memblock_limit);
                }
        }

        memblock_set_current_limit(memblock_limit);
}

static inline void prepare_page_table(void)
{
        unsigned long addr;
        phys_addr_t end;

        /*
         * Clear out all the mappings below the kernel image.
         */
#ifdef CONFIG_KASAN
        /*
         * KASan's shadow memory inserts itself between the TASK_SIZE
         * and MODULES_VADDR. Do not clear the KASan shadow memory mappings.
         */
        for (addr = 0; addr < KASAN_SHADOW_START; addr += PMD_SIZE)
                pmd_clear(pmd_off_k(addr));
        /*
         * Skip over the KASan shadow area. KASAN_SHADOW_END is sometimes
         * equal to MODULES_VADDR and then we exit the pmd clearing. If we
         * are using a thumb-compiled kernel, there there will be 8MB more
         * to clear as KASan always offset to 16 MB below MODULES_VADDR.
         */
        for (addr = KASAN_SHADOW_END; addr < MODULES_VADDR; addr += PMD_SIZE)
                pmd_clear(pmd_off_k(addr));
#else
        for (addr = 0; addr < MODULES_VADDR; addr += PMD_SIZE)
                pmd_clear(pmd_off_k(addr));
#endif

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

        /*
         * Find the end of the first block of lowmem.
         */
        end = memblock.memory.regions[0].base + memblock.memory.regions[0].size;
        if (end >= arm_lowmem_limit)
                end = arm_lowmem_limit;

        /*
         * Clear out all the kernel space mappings, except for the first
         * memory bank, up to the vmalloc region.
         */
        for (addr = __phys_to_virt(end);
             addr < VMALLOC_START; addr += PMD_SIZE)
                pmd_clear(pmd_off_k(addr));
}

#ifdef CONFIG_ARM_LPAE
/* the first page is reserved for pgd */
#define SWAPPER_PG_DIR_SIZE     (PAGE_SIZE + \
                                 PTRS_PER_PGD * PTRS_PER_PMD * sizeof(pmd_t))
#else
#define SWAPPER_PG_DIR_SIZE     (PTRS_PER_PGD * sizeof(pgd_t))
#endif

/*
 * Reserve the special regions of memory
 */
void __init arm_mm_memblock_reserve(void)
{
        /*
         * Reserve the page tables.  These are already in use,
         * and can only be in node 0.
         */
        memblock_reserve(__pa(swapper_pg_dir), SWAPPER_PG_DIR_SIZE);

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

/*
 * Set up the device mappings.  Since we clear out the page tables for all
 * mappings above VMALLOC_START, except early fixmap, we might remove debug
 * device mappings.  This means earlycon can be used to debug this function
 * Any other function or debugging method which may touch any device _will_
 * crash the kernel.
 */
static void __init devicemaps_init(const struct machine_desc *mdesc)
{
        struct map_desc map;
        unsigned long addr;
        void *vectors;

        /*
         * Allocate the vector page early.
         */
        vectors = early_alloc(PAGE_SIZE * 2);

        early_trap_init(vectors);

        /*
         * Clear page table except top pmd used by early fixmaps
         */
        for (addr = VMALLOC_START; addr < (FIXADDR_TOP & PMD_MASK); addr += PMD_SIZE)
                pmd_clear(pmd_off_k(addr));

        if (__atags_pointer) {
                /* create a read-only mapping of the device tree */
                map.pfn = __phys_to_pfn(__atags_pointer & SECTION_MASK);
                map.virtual = FDT_FIXED_BASE;
                map.length = FDT_FIXED_SIZE;
                map.type = MT_ROM;
                create_mapping(&map);
        }

        /*
         * 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 = MODULES_VADDR;
        map.length = ((unsigned long)_exiprom - 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;
#ifdef CONFIG_KUSER_HELPERS
        map.type = MT_HIGH_VECTORS;
#else
        map.type = MT_LOW_VECTORS;
#endif
        create_mapping(&map);

        if (!vectors_high()) {
                map.virtual = 0;
                map.length = PAGE_SIZE * 2;
                map.type = MT_LOW_VECTORS;
                create_mapping(&map);
        }

        /* Now create a kernel read-only mapping */
        map.pfn += 1;
        map.virtual = 0xffff0000 + PAGE_SIZE;
        map.length = PAGE_SIZE;
        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();
        else
                debug_ll_io_init();
        fill_pmd_gaps();

        /* Reserve fixed i/o space in VMALLOC region */
        pci_reserve_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();

        /* Enable asynchronous aborts */
        early_abt_enable();
}

static void __init kmap_init(void)
{
#ifdef CONFIG_HIGHMEM
        pkmap_page_table = early_pte_alloc(pmd_off_k(PKMAP_BASE),
                PKMAP_BASE, _PAGE_KERNEL_TABLE);
#endif

        early_pte_alloc(pmd_off_k(FIXADDR_START), FIXADDR_START,
                        _PAGE_KERNEL_TABLE);
}

static void __init map_lowmem(void)
{
        phys_addr_t kernel_x_start = round_down(__pa(KERNEL_START), SECTION_SIZE);
        phys_addr_t kernel_x_end = round_up(__pa(__init_end), SECTION_SIZE);
        phys_addr_t start, end;
        u64 i;

        /* Map all the lowmem memory banks. */
        for_each_mem_range(i, &start, &end) {
                struct map_desc map;

                if (end > arm_lowmem_limit)
                        end = arm_lowmem_limit;
                if (start >= end)
                        break;

                if (end < kernel_x_start) {
                        map.pfn = __phys_to_pfn(start);
                        map.virtual = __phys_to_virt(start);
                        map.length = end - start;
                        map.type = MT_MEMORY_RWX;

                        create_mapping(&map);
                } else if (start >= kernel_x_end) {
                        map.pfn = __phys_to_pfn(start);
                        map.virtual = __phys_to_virt(start);
                        map.length = end - start;
                        map.type = MT_MEMORY_RW;

                        create_mapping(&map);
                } else {
                        /* This better cover the entire kernel */
                        if (start < kernel_x_start) {
                                map.pfn = __phys_to_pfn(start);
                                map.virtual = __phys_to_virt(start);
                                map.length = kernel_x_start - start;
                                map.type = MT_MEMORY_RW;

                                create_mapping(&map);
                        }

                        map.pfn = __phys_to_pfn(kernel_x_start);
                        map.virtual = __phys_to_virt(kernel_x_start);
                        map.length = kernel_x_end - kernel_x_start;
                        map.type = MT_MEMORY_RWX;

                        create_mapping(&map);

                        if (kernel_x_end < end) {
                                map.pfn = __phys_to_pfn(kernel_x_end);
                                map.virtual = __phys_to_virt(kernel_x_end);
                                map.length = end - kernel_x_end;
                                map.type = MT_MEMORY_RW;

                                create_mapping(&map);
                        }
                }
        }
}

#ifdef CONFIG_ARM_PV_FIXUP
typedef void pgtables_remap(long long offset, unsigned long pgd);
pgtables_remap lpae_pgtables_remap_asm;

/*
 * early_paging_init() recreates boot time page table setup, allowing machines
 * to switch over to a high (>4G) address space on LPAE systems
 */
static void __init early_paging_init(const struct machine_desc *mdesc)
{
        pgtables_remap *lpae_pgtables_remap;
        unsigned long pa_pgd;
        unsigned int cr, ttbcr;
        long long offset;

        if (!mdesc->pv_fixup)
                return;

        offset = mdesc->pv_fixup();
        if (offset == 0)
                return;

        /*
         * Get the address of the remap function in the 1:1 identity
         * mapping setup by the early page table assembly code.  We
         * must get this prior to the pv update.  The following barrier
         * ensures that this is complete before we fixup any P:V offsets.
         */
        lpae_pgtables_remap = (pgtables_remap *)(unsigned long)__pa(lpae_pgtables_remap_asm);
        pa_pgd = __pa(swapper_pg_dir);
        barrier();

        pr_info("Switching physical address space to 0x%08llx\n",
                (u64)PHYS_OFFSET + offset);

        /* Re-set the phys pfn offset, and the pv offset */
        __pv_offset += offset;
        __pv_phys_pfn_offset += PFN_DOWN(offset);

        /* Run the patch stub to update the constants */
        fixup_pv_table(&__pv_table_begin,
                (&__pv_table_end - &__pv_table_begin) << 2);

        /*
         * We changing not only the virtual to physical mapping, but also
         * the physical addresses used to access memory.  We need to flush
         * all levels of cache in the system with caching disabled to
         * ensure that all data is written back, and nothing is prefetched
         * into the caches.  We also need to prevent the TLB walkers
         * allocating into the caches too.  Note that this is ARMv7 LPAE
         * specific.
         */
        cr = get_cr();
        set_cr(cr & ~(CR_I | CR_C));
        asm("mrc p15, 0, %0, c2, c0, 2" : "=r" (ttbcr));
        asm volatile("mcr p15, 0, %0, c2, c0, 2"
                : : "r" (ttbcr & ~(3 << 8 | 3 << 10)));
        flush_cache_all();

        /*
         * Fixup the page tables - this must be in the idmap region as
         * we need to disable the MMU to do this safely, and hence it
         * needs to be assembly.  It's fairly simple, as we're using the
         * temporary tables setup by the initial assembly code.
         */
        lpae_pgtables_remap(offset, pa_pgd);

        /* Re-enable the caches and cacheable TLB walks */
        asm volatile("mcr p15, 0, %0, c2, c0, 2" : : "r" (ttbcr));
        set_cr(cr);
}

#else

static void __init early_paging_init(const struct machine_desc *mdesc)
{
        long long offset;

        if (!mdesc->pv_fixup)
                return;

        offset = mdesc->pv_fixup();
        if (offset == 0)
                return;

        pr_crit("Physical address space modification is only to support Keystone2.\n");
        pr_crit("Please enable ARM_LPAE and ARM_PATCH_PHYS_VIRT support to use this\n");
        pr_crit("feature. Your kernel may crash now, have a good day.\n");
        add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_STILL_OK);
}

#endif

static void __init early_fixmap_shutdown(void)
{
        int i;
        unsigned long va = fix_to_virt(__end_of_permanent_fixed_addresses - 1);

        pte_offset_fixmap = pte_offset_late_fixmap;
        pmd_clear(fixmap_pmd(va));
        local_flush_tlb_kernel_page(va);

        for (i = 0; i < __end_of_permanent_fixed_addresses; i++) {
                pte_t *pte;
                struct map_desc map;

                map.virtual = fix_to_virt(i);
                pte = pte_offset_early_fixmap(pmd_off_k(map.virtual), map.virtual);

                /* Only i/o device mappings are supported ATM */
                if (pte_none(*pte) ||
                    (pte_val(*pte) & L_PTE_MT_MASK) != L_PTE_MT_DEV_SHARED)
                        continue;

                map.pfn = pte_pfn(*pte);
                map.type = MT_DEVICE;
                map.length = PAGE_SIZE;

                create_mapping(&map);
        }
}

/*
 * 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(const struct machine_desc *mdesc)
{
        void *zero_page;

        prepare_page_table();
        map_lowmem();
        memblock_set_current_limit(arm_lowmem_limit);
        dma_contiguous_remap();
        early_fixmap_shutdown();
        devicemaps_init(mdesc);
        kmap_init();
        tcm_init();

        top_pmd = pmd_off_k(0xffff0000);

        /* allocate the zero page. */
        zero_page = early_alloc(PAGE_SIZE);

        bootmem_init();

        empty_zero_page = virt_to_page(zero_page);
        __flush_dcache_page(NULL, empty_zero_page);
}

void __init early_mm_init(const struct machine_desc *mdesc)
{
        build_mem_type_table();
        early_paging_init(mdesc);
}

void set_pte_at(struct mm_struct *mm, unsigned long addr,
                              pte_t *ptep, pte_t pteval)
{
        unsigned long ext = 0;

        if (addr < TASK_SIZE && pte_valid_user(pteval)) {
                if (!pte_special(pteval))
                        __sync_icache_dcache(pteval);
                ext |= PTE_EXT_NG;
        }

        set_pte_ext(ptep, pteval, ext);
}