// SPDX-License-Identifier: GPL-2.0
/*
 * Common EFI (Extensible Firmware Interface) support functions
 * Based on Extensible Firmware Interface Specification version 1.0
 *
 * Copyright (C) 1999 VA Linux Systems
 * Copyright (C) 1999 Walt Drummond <drummond@valinux.com>
 * Copyright (C) 1999-2002 Hewlett-Packard Co.
 *      David Mosberger-Tang <davidm@hpl.hp.com>
 *      Stephane Eranian <eranian@hpl.hp.com>
 * Copyright (C) 2005-2008 Intel Co.
 *      Fenghua Yu <fenghua.yu@intel.com>
 *      Bibo Mao <bibo.mao@intel.com>
 *      Chandramouli Narayanan <mouli@linux.intel.com>
 *      Huang Ying <ying.huang@intel.com>
 * Copyright (C) 2013 SuSE Labs
 *      Borislav Petkov <bp@suse.de> - runtime services VA mapping
 *
 * Copied from efi_32.c to eliminate the duplicated code between EFI
 * 32/64 support code. --ying 2007-10-26
 *
 * All EFI Runtime Services are not implemented yet as EFI only
 * supports physical mode addressing on SoftSDV. This is to be fixed
 * in a future version.  --drummond 1999-07-20
 *
 * Implemented EFI runtime services and virtual mode calls.  --davidm
 *
 * Goutham Rao: <goutham.rao@intel.com>
 *      Skip non-WB memory and ignore empty memory ranges.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/efi.h>
#include <linux/efi-bgrt.h>
#include <linux/export.h>
#include <linux/memblock.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/uaccess.h>
#include <linux/time.h>
#include <linux/io.h>
#include <linux/reboot.h>
#include <linux/bcd.h>

#include <asm/setup.h>
#include <asm/efi.h>
#include <asm/e820/api.h>
#include <asm/time.h>
#include <asm/set_memory.h>
#include <asm/tlbflush.h>
#include <asm/x86_init.h>
#include <asm/uv/uv.h>

static efi_system_table_t efi_systab __initdata;
static u64 efi_systab_phys __initdata;

static efi_config_table_type_t arch_tables[] __initdata = {
#ifdef CONFIG_X86_UV
        {UV_SYSTEM_TABLE_GUID, "UVsystab", &uv_systab_phys},
#endif
        {NULL_GUID, NULL, NULL},
};

static const unsigned long * const efi_tables[] = {
        &efi.mps,
        &efi.acpi,
        &efi.acpi20,
        &efi.smbios,
        &efi.smbios3,
        &efi.boot_info,
        &efi.hcdp,
        &efi.uga,
#ifdef CONFIG_X86_UV
        &uv_systab_phys,
#endif
        &efi.fw_vendor,
        &efi.runtime,
        &efi.config_table,
        &efi.esrt,
        &efi.properties_table,
        &efi.mem_attr_table,
#ifdef CONFIG_EFI_RCI2_TABLE
        &rci2_table_phys,
#endif
};

u64 efi_setup;          /* efi setup_data physical address */

static int add_efi_memmap __initdata;
static int __init setup_add_efi_memmap(char *arg)
{
        add_efi_memmap = 1;
        return 0;
}
early_param("add_efi_memmap", setup_add_efi_memmap);

void __init efi_find_mirror(void)
{
        efi_memory_desc_t *md;
        u64 mirror_size = 0, total_size = 0;

        if (!efi_enabled(EFI_MEMMAP))
                return;

        for_each_efi_memory_desc(md) {
                unsigned long long start = md->phys_addr;
                unsigned long long size = md->num_pages << EFI_PAGE_SHIFT;

                total_size += size;
                if (md->attribute & EFI_MEMORY_MORE_RELIABLE) {
                        memblock_mark_mirror(start, size);
                        mirror_size += size;
                }
        }
        if (mirror_size)
                pr_info("Memory: %lldM/%lldM mirrored memory\n",
                        mirror_size>>20, total_size>>20);
}

/*
 * Tell the kernel about the EFI memory map.  This might include
 * more than the max 128 entries that can fit in the passed in e820
 * legacy (zeropage) memory map, but the kernel's e820 table can hold
 * E820_MAX_ENTRIES.
 */

static void __init do_add_efi_memmap(void)
{
        efi_memory_desc_t *md;

        if (!efi_enabled(EFI_MEMMAP))
                return;

        for_each_efi_memory_desc(md) {
                unsigned long long start = md->phys_addr;
                unsigned long long size = md->num_pages << EFI_PAGE_SHIFT;
                int e820_type;

                switch (md->type) {
                case EFI_LOADER_CODE:
                case EFI_LOADER_DATA:
                case EFI_BOOT_SERVICES_CODE:
                case EFI_BOOT_SERVICES_DATA:
                case EFI_CONVENTIONAL_MEMORY:
                        if (efi_soft_reserve_enabled()
                            && (md->attribute & EFI_MEMORY_SP))
                                e820_type = E820_TYPE_SOFT_RESERVED;
                        else if (md->attribute & EFI_MEMORY_WB)
                                e820_type = E820_TYPE_RAM;
                        else
                                e820_type = E820_TYPE_RESERVED;
                        break;
                case EFI_ACPI_RECLAIM_MEMORY:
                        e820_type = E820_TYPE_ACPI;
                        break;
                case EFI_ACPI_MEMORY_NVS:
                        e820_type = E820_TYPE_NVS;
                        break;
                case EFI_UNUSABLE_MEMORY:
                        e820_type = E820_TYPE_UNUSABLE;
                        break;
                case EFI_PERSISTENT_MEMORY:
                        e820_type = E820_TYPE_PMEM;
                        break;
                default:
                        /*
                         * EFI_RESERVED_TYPE EFI_RUNTIME_SERVICES_CODE
                         * EFI_RUNTIME_SERVICES_DATA EFI_MEMORY_MAPPED_IO
                         * EFI_MEMORY_MAPPED_IO_PORT_SPACE EFI_PAL_CODE
                         */
                        e820_type = E820_TYPE_RESERVED;
                        break;
                }

                e820__range_add(start, size, e820_type);
        }
        e820__update_table(e820_table);
}

/*
 * Given add_efi_memmap defaults to 0 and there there is no alternative
 * e820 mechanism for soft-reserved memory, import the full EFI memory
 * map if soft reservations are present and enabled. Otherwise, the
 * mechanism to disable the kernel's consideration of EFI_MEMORY_SP is
 * the efi=nosoftreserve option.
 */
static bool do_efi_soft_reserve(void)
{
        efi_memory_desc_t *md;

        if (!efi_enabled(EFI_MEMMAP))
                return false;

        if (!efi_soft_reserve_enabled())
                return false;

        for_each_efi_memory_desc(md)
                if (md->type == EFI_CONVENTIONAL_MEMORY &&
                    (md->attribute & EFI_MEMORY_SP))
                        return true;
        return false;
}

int __init efi_memblock_x86_reserve_range(void)
{
        struct efi_info *e = &boot_params.efi_info;
        struct efi_memory_map_data data;
        phys_addr_t pmap;
        int rv;

        if (efi_enabled(EFI_PARAVIRT))
                return 0;

#ifdef CONFIG_X86_32
        /* Can't handle data above 4GB at this time */
        if (e->efi_memmap_hi) {
                pr_err("Memory map is above 4GB, disabling EFI.\n");
                return -EINVAL;
        }
        pmap =  e->efi_memmap;
#else
        pmap = (e->efi_memmap | ((__u64)e->efi_memmap_hi << 32));
#endif
        data.phys_map           = pmap;
        data.size               = e->efi_memmap_size;
        data.desc_size          = e->efi_memdesc_size;
        data.desc_version       = e->efi_memdesc_version;

        rv = efi_memmap_init_early(&data);
        if (rv)
                return rv;

        if (add_efi_memmap || do_efi_soft_reserve())
                do_add_efi_memmap();

        efi_fake_memmap_early();

        WARN(efi.memmap.desc_version != 1,
             "Unexpected EFI_MEMORY_DESCRIPTOR version %ld",
             efi.memmap.desc_version);

        memblock_reserve(pmap, efi.memmap.nr_map * efi.memmap.desc_size);

        return 0;
}

#define OVERFLOW_ADDR_SHIFT     (64 - EFI_PAGE_SHIFT)
#define OVERFLOW_ADDR_MASK      (U64_MAX << OVERFLOW_ADDR_SHIFT)
#define U64_HIGH_BIT            (~(U64_MAX >> 1))

static bool __init efi_memmap_entry_valid(const efi_memory_desc_t *md, int i)
{
        u64 end = (md->num_pages << EFI_PAGE_SHIFT) + md->phys_addr - 1;
        u64 end_hi = 0;
        char buf[64];

        if (md->num_pages == 0) {
                end = 0;
        } else if (md->num_pages > EFI_PAGES_MAX ||
                   EFI_PAGES_MAX - md->num_pages <
                   (md->phys_addr >> EFI_PAGE_SHIFT)) {
                end_hi = (md->num_pages & OVERFLOW_ADDR_MASK)
                        >> OVERFLOW_ADDR_SHIFT;

                if ((md->phys_addr & U64_HIGH_BIT) && !(end & U64_HIGH_BIT))
                        end_hi += 1;
        } else {
                return true;
        }

        pr_warn_once(FW_BUG "Invalid EFI memory map entries:\n");

        if (end_hi) {
                pr_warn("mem%02u: %s range=[0x%016llx-0x%llx%016llx] (invalid)\n",
                        i, efi_md_typeattr_format(buf, sizeof(buf), md),
                        md->phys_addr, end_hi, end);
        } else {
                pr_warn("mem%02u: %s range=[0x%016llx-0x%016llx] (invalid)\n",
                        i, efi_md_typeattr_format(buf, sizeof(buf), md),
                        md->phys_addr, end);
        }
        return false;
}

static void __init efi_clean_memmap(void)
{
        efi_memory_desc_t *out = efi.memmap.map;
        const efi_memory_desc_t *in = out;
        const efi_memory_desc_t *end = efi.memmap.map_end;
        int i, n_removal;

        for (i = n_removal = 0; in < end; i++) {
                if (efi_memmap_entry_valid(in, i)) {
                        if (out != in)
                                memcpy(out, in, efi.memmap.desc_size);
                        out = (void *)out + efi.memmap.desc_size;
                } else {
                        n_removal++;
                }
                in = (void *)in + efi.memmap.desc_size;
        }

        if (n_removal > 0) {
                struct efi_memory_map_data data = {
                        .phys_map = efi.memmap.phys_map,
                        .desc_version = efi.memmap.desc_version,
                        .desc_size = efi.memmap.desc_size,
                        .size = efi.memmap.desc_size * (efi.memmap.nr_map - n_removal),
                        .flags = 0,
                };

                pr_warn("Removing %d invalid memory map entries.\n", n_removal);
                efi_memmap_install(&data);
        }
}

void __init efi_print_memmap(void)
{
        efi_memory_desc_t *md;
        int i = 0;

        for_each_efi_memory_desc(md) {
                char buf[64];

                pr_info("mem%02u: %s range=[0x%016llx-0x%016llx] (%lluMB)\n",
                        i++, efi_md_typeattr_format(buf, sizeof(buf), md),
                        md->phys_addr,
                        md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT) - 1,
                        (md->num_pages >> (20 - EFI_PAGE_SHIFT)));
        }
}

static int __init efi_systab_init(u64 phys)
{
        int size = efi_enabled(EFI_64BIT) ? sizeof(efi_system_table_64_t)
                                          : sizeof(efi_system_table_32_t);
        bool over4g = false;
        void *p;

        p = early_memremap_ro(phys, size);
        if (p == NULL) {
                pr_err("Couldn't map the system table!\n");
                return -ENOMEM;
        }

        if (efi_enabled(EFI_64BIT)) {
                const efi_system_table_64_t *systab64 = p;

                efi_systab.hdr                  = systab64->hdr;
                efi_systab.fw_vendor            = systab64->fw_vendor;
                efi_systab.fw_revision          = systab64->fw_revision;
                efi_systab.con_in_handle        = systab64->con_in_handle;
                efi_systab.con_in               = systab64->con_in;
                efi_systab.con_out_handle       = systab64->con_out_handle;
                efi_systab.con_out              = (void *)(unsigned long)systab64->con_out;
                efi_systab.stderr_handle        = systab64->stderr_handle;
                efi_systab.stderr               = systab64->stderr;
                efi_systab.runtime              = (void *)(unsigned long)systab64->runtime;
                efi_systab.boottime             = (void *)(unsigned long)systab64->boottime;
                efi_systab.nr_tables            = systab64->nr_tables;
                efi_systab.tables               = systab64->tables;

                over4g = systab64->con_in_handle        > U32_MAX ||
                         systab64->con_in               > U32_MAX ||
                         systab64->con_out_handle       > U32_MAX ||
                         systab64->con_out              > U32_MAX ||
                         systab64->stderr_handle        > U32_MAX ||
                         systab64->stderr               > U32_MAX ||
                         systab64->boottime             > U32_MAX;

                if (efi_setup) {
                        struct efi_setup_data *data;

                        data = early_memremap_ro(efi_setup, sizeof(*data));
                        if (!data) {
                                early_memunmap(p, size);
                                return -ENOMEM;
                        }

                        efi_systab.fw_vendor    = (unsigned long)data->fw_vendor;
                        efi_systab.runtime      = (void *)(unsigned long)data->runtime;
                        efi_systab.tables       = (unsigned long)data->tables;

                        over4g |= data->fw_vendor       > U32_MAX ||
                                  data->runtime         > U32_MAX ||
                                  data->tables          > U32_MAX;

                        early_memunmap(data, sizeof(*data));
                } else {
                        over4g |= systab64->fw_vendor   > U32_MAX ||
                                  systab64->runtime     > U32_MAX ||
                                  systab64->tables      > U32_MAX;
                }
        } else {
                const efi_system_table_32_t *systab32 = p;

                efi_systab.hdr                  = systab32->hdr;
                efi_systab.fw_vendor            = systab32->fw_vendor;
                efi_systab.fw_revision          = systab32->fw_revision;
                efi_systab.con_in_handle        = systab32->con_in_handle;
                efi_systab.con_in               = systab32->con_in;
                efi_systab.con_out_handle       = systab32->con_out_handle;
                efi_systab.con_out              = (void *)(unsigned long)systab32->con_out;
                efi_systab.stderr_handle        = systab32->stderr_handle;
                efi_systab.stderr               = systab32->stderr;
                efi_systab.runtime              = (void *)(unsigned long)systab32->runtime;
                efi_systab.boottime             = (void *)(unsigned long)systab32->boottime;
                efi_systab.nr_tables            = systab32->nr_tables;
                efi_systab.tables               = systab32->tables;
        }

        early_memunmap(p, size);

        if (IS_ENABLED(CONFIG_X86_32) && over4g) {
                pr_err("EFI data located above 4GB, disabling EFI.\n");
                return -EINVAL;
        }

        efi.systab = &efi_systab;

        /*
         * Verify the EFI Table
         */
        if (efi.systab->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE) {
                pr_err("System table signature incorrect!\n");
                return -EINVAL;
        }
        if ((efi.systab->hdr.revision >> 16) == 0)
                pr_err("Warning: System table version %d.%02d, expected 1.00 or greater!\n",
                       efi.systab->hdr.revision >> 16,
                       efi.systab->hdr.revision & 0xffff);

        return 0;
}

void __init efi_init(void)
{
        efi_char16_t *c16;
        char vendor[100] = "unknown";
        int i = 0;

        if (IS_ENABLED(CONFIG_X86_32) &&
            (boot_params.efi_info.efi_systab_hi ||
             boot_params.efi_info.efi_memmap_hi)) {
                pr_info("Table located above 4GB, disabling EFI.\n");
                return;
        }

        efi_systab_phys = boot_params.efi_info.efi_systab |
                          ((__u64)boot_params.efi_info.efi_systab_hi << 32);

        if (efi_systab_init(efi_systab_phys))
                return;

        efi.config_table = (unsigned long)efi.systab->tables;
        efi.fw_vendor    = (unsigned long)efi.systab->fw_vendor;
        efi.runtime      = (unsigned long)efi.systab->runtime;

        /*
         * Show what we know for posterity
         */
        c16 = early_memremap_ro(efi.systab->fw_vendor,
                                sizeof(vendor) * sizeof(efi_char16_t));
        if (c16) {
                for (i = 0; i < sizeof(vendor) - 1 && c16[i]; ++i)
                        vendor[i] = c16[i];
                vendor[i] = '\0';
                early_memunmap(c16, sizeof(vendor) * sizeof(efi_char16_t));
        } else {
                pr_err("Could not map the firmware vendor!\n");
        }

        pr_info("EFI v%u.%.02u by %s\n",
                efi.systab->hdr.revision >> 16,
                efi.systab->hdr.revision & 0xffff, vendor);

        if (efi_reuse_config(efi.systab->tables, efi.systab->nr_tables))
                return;

        if (efi_config_init(arch_tables))
                return;

        /*
         * Note: We currently don't support runtime services on an EFI
         * that doesn't match the kernel 32/64-bit mode.
         */

        if (!efi_runtime_supported())
                pr_info("No EFI runtime due to 32/64-bit mismatch with kernel\n");

        if (!efi_runtime_supported() || efi_runtime_disabled()) {
                efi_memmap_unmap();
                return;
        }

        set_bit(EFI_RUNTIME_SERVICES, &efi.flags);
        efi_clean_memmap();

        if (efi_enabled(EFI_DBG))
                efi_print_memmap();
}

#if defined(CONFIG_X86_32) || defined(CONFIG_X86_UV)

void __init efi_set_executable(efi_memory_desc_t *md, bool executable)
{
        u64 addr, npages;

        addr = md->virt_addr;
        npages = md->num_pages;

        memrange_efi_to_native(&addr, &npages);

        if (executable)
                set_memory_x(addr, npages);
        else
                set_memory_nx(addr, npages);
}

void __init runtime_code_page_mkexec(void)
{
        efi_memory_desc_t *md;

        /* Make EFI runtime service code area executable */
        for_each_efi_memory_desc(md) {
                if (md->type != EFI_RUNTIME_SERVICES_CODE)
                        continue;

                efi_set_executable(md, true);
        }
}

void __init efi_memory_uc(u64 addr, unsigned long size)
{
        unsigned long page_shift = 1UL << EFI_PAGE_SHIFT;
        u64 npages;

        npages = round_up(size, page_shift) / page_shift;
        memrange_efi_to_native(&addr, &npages);
        set_memory_uc(addr, npages);
}

void __init old_map_region(efi_memory_desc_t *md)
{
        u64 start_pfn, end_pfn, end;
        unsigned long size;
        void *va;

        start_pfn = PFN_DOWN(md->phys_addr);
        size      = md->num_pages << PAGE_SHIFT;
        end       = md->phys_addr + size;
        end_pfn   = PFN_UP(end);

        if (pfn_range_is_mapped(start_pfn, end_pfn)) {
                va = __va(md->phys_addr);

                if (!(md->attribute & EFI_MEMORY_WB))
                        efi_memory_uc((u64)(unsigned long)va, size);
        } else
                va = efi_ioremap(md->phys_addr, size,
                                 md->type, md->attribute);

        md->virt_addr = (u64) (unsigned long) va;
        if (!va)
                pr_err("ioremap of 0x%llX failed!\n",
                       (unsigned long long)md->phys_addr);
}

#endif

/* Merge contiguous regions of the same type and attribute */
static void __init efi_merge_regions(void)
{
        efi_memory_desc_t *md, *prev_md = NULL;

        for_each_efi_memory_desc(md) {
                u64 prev_size;

                if (!prev_md) {
                        prev_md = md;
                        continue;
                }

                if (prev_md->type != md->type ||
                    prev_md->attribute != md->attribute) {
                        prev_md = md;
                        continue;
                }

                prev_size = prev_md->num_pages << EFI_PAGE_SHIFT;

                if (md->phys_addr == (prev_md->phys_addr + prev_size)) {
                        prev_md->num_pages += md->num_pages;
                        md->type = EFI_RESERVED_TYPE;
                        md->attribute = 0;
                        continue;
                }
                prev_md = md;
        }
}

static void __init get_systab_virt_addr(efi_memory_desc_t *md)
{
        unsigned long size;
        u64 end, systab;

        size = md->num_pages << EFI_PAGE_SHIFT;
        end = md->phys_addr + size;
        systab = efi_systab_phys;
        if (md->phys_addr <= systab && systab < end) {
                systab += md->virt_addr - md->phys_addr;
                efi.systab = (efi_system_table_t *)(unsigned long)systab;
        }
}

static void *realloc_pages(void *old_memmap, int old_shift)
{
        void *ret;

        ret = (void *)__get_free_pages(GFP_KERNEL, old_shift + 1);
        if (!ret)
                goto out;

        /*
         * A first-time allocation doesn't have anything to copy.
         */
        if (!old_memmap)
                return ret;

        memcpy(ret, old_memmap, PAGE_SIZE << old_shift);

out:
        free_pages((unsigned long)old_memmap, old_shift);
        return ret;
}

/*
 * Iterate the EFI memory map in reverse order because the regions
 * will be mapped top-down. The end result is the same as if we had
 * mapped things forward, but doesn't require us to change the
 * existing implementation of efi_map_region().
 */
static inline void *efi_map_next_entry_reverse(void *entry)
{
        /* Initial call */
        if (!entry)
                return efi.memmap.map_end - efi.memmap.desc_size;

        entry -= efi.memmap.desc_size;
        if (entry < efi.memmap.map)
                return NULL;

        return entry;
}

/*
 * efi_map_next_entry - Return the next EFI memory map descriptor
 * @entry: Previous EFI memory map descriptor
 *
 * This is a helper function to iterate over the EFI memory map, which
 * we do in different orders depending on the current configuration.
 *
 * To begin traversing the memory map @entry must be %NULL.
 *
 * Returns %NULL when we reach the end of the memory map.
 */
static void *efi_map_next_entry(void *entry)
{
        if (!efi_have_uv1_memmap() && efi_enabled(EFI_64BIT)) {
                /*
                 * Starting in UEFI v2.5 the EFI_PROPERTIES_TABLE
                 * config table feature requires us to map all entries
                 * in the same order as they appear in the EFI memory
                 * map. That is to say, entry N must have a lower
                 * virtual address than entry N+1. This is because the
                 * firmware toolchain leaves relative references in
                 * the code/data sections, which are split and become
                 * separate EFI memory regions. Mapping things
                 * out-of-order leads to the firmware accessing
                 * unmapped addresses.
                 *
                 * Since we need to map things this way whether or not
                 * the kernel actually makes use of
                 * EFI_PROPERTIES_TABLE, let's just switch to this
                 * scheme by default for 64-bit.
                 */
                return efi_map_next_entry_reverse(entry);
        }

        /* Initial call */
        if (!entry)
                return efi.memmap.map;

        entry += efi.memmap.desc_size;
        if (entry >= efi.memmap.map_end)
                return NULL;

        return entry;
}

static bool should_map_region(efi_memory_desc_t *md)
{
        /*
         * Runtime regions always require runtime mappings (obviously).
         */
        if (md->attribute & EFI_MEMORY_RUNTIME)
                return true;

        /*
         * 32-bit EFI doesn't suffer from the bug that requires us to
         * reserve boot services regions, and mixed mode support
         * doesn't exist for 32-bit kernels.
         */
        if (IS_ENABLED(CONFIG_X86_32))
                return false;

        /*
         * EFI specific purpose memory may be reserved by default
         * depending on kernel config and boot options.
         */
        if (md->type == EFI_CONVENTIONAL_MEMORY &&
            efi_soft_reserve_enabled() &&
            (md->attribute & EFI_MEMORY_SP))
                return false;

        /*
         * Map all of RAM so that we can access arguments in the 1:1
         * mapping when making EFI runtime calls.
         */
        if (efi_is_mixed()) {
                if (md->type == EFI_CONVENTIONAL_MEMORY ||
                    md->type == EFI_LOADER_DATA ||
                    md->type == EFI_LOADER_CODE)
                        return true;
        }

        /*
         * Map boot services regions as a workaround for buggy
         * firmware that accesses them even when they shouldn't.
         *
         * See efi_{reserve,free}_boot_services().
         */
        if (md->type == EFI_BOOT_SERVICES_CODE ||
            md->type == EFI_BOOT_SERVICES_DATA)
                return true;

        return false;
}

/*
 * Map the efi memory ranges of the runtime services and update new_mmap with
 * virtual addresses.
 */
static void * __init efi_map_regions(int *count, int *pg_shift)
{
        void *p, *new_memmap = NULL;
        unsigned long left = 0;
        unsigned long desc_size;
        efi_memory_desc_t *md;

        desc_size = efi.memmap.desc_size;

        p = NULL;
        while ((p = efi_map_next_entry(p))) {
                md = p;

                if (!should_map_region(md))
                        continue;

                efi_map_region(md);
                get_systab_virt_addr(md);

                if (left < desc_size) {
                        new_memmap = realloc_pages(new_memmap, *pg_shift);
                        if (!new_memmap)
                                return NULL;

                        left += PAGE_SIZE << *pg_shift;
                        (*pg_shift)++;
                }

                memcpy(new_memmap + (*count * desc_size), md, desc_size);

                left -= desc_size;
                (*count)++;
        }

        return new_memmap;
}

static void __init kexec_enter_virtual_mode(void)
{
#ifdef CONFIG_KEXEC_CORE
        efi_memory_desc_t *md;
        unsigned int num_pages;

        efi.systab = NULL;

        /*
         * We don't do virtual mode, since we don't do runtime services, on
         * non-native EFI. With the UV1 memmap, we don't do runtime services in
         * kexec kernel because in the initial boot something else might
         * have been mapped at these virtual addresses.
         */
        if (efi_is_mixed() || efi_have_uv1_memmap()) {
                efi_memmap_unmap();
                clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);
                return;
        }

        if (efi_alloc_page_tables()) {
                pr_err("Failed to allocate EFI page tables\n");
                clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);
                return;
        }

        /*
        * Map efi regions which were passed via setup_data. The virt_addr is a
        * fixed addr which was used in first kernel of a kexec boot.
        */
        for_each_efi_memory_desc(md) {
                efi_map_region_fixed(md); /* FIXME: add error handling */
                get_systab_virt_addr(md);
        }

        /*
         * Unregister the early EFI memmap from efi_init() and install
         * the new EFI memory map.
         */
        efi_memmap_unmap();

        if (efi_memmap_init_late(efi.memmap.phys_map,
                                 efi.memmap.desc_size * efi.memmap.nr_map)) {
                pr_err("Failed to remap late EFI memory map\n");
                clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);
                return;
        }

        BUG_ON(!efi.systab);

        num_pages = ALIGN(efi.memmap.nr_map * efi.memmap.desc_size, PAGE_SIZE);
        num_pages >>= PAGE_SHIFT;

        if (efi_setup_page_tables(efi.memmap.phys_map, num_pages)) {
                clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);
                return;
        }

        efi_sync_low_kernel_mappings();

        /*
         * Now that EFI is in virtual mode, update the function
         * pointers in the runtime service table to the new virtual addresses.
         *
         * Call EFI services through wrapper functions.
         */
        efi.runtime_version = efi_systab.hdr.revision;

        efi_native_runtime_setup();
#endif
}

/*
 * This function will switch the EFI runtime services to virtual mode.
 * Essentially, we look through the EFI memmap and map every region that
 * has the runtime attribute bit set in its memory descriptor into the
 * efi_pgd page table.
 *
 * The old method which used to update that memory descriptor with the
 * virtual address obtained from ioremap() is still supported when the
 * kernel is booted on SG1 UV1 hardware. Same old method enabled the
 * runtime services to be called without having to thunk back into
 * physical mode for every invocation.
 *
 * The new method does a pagetable switch in a preemption-safe manner
 * so that we're in a different address space when calling a runtime
 * function. For function arguments passing we do copy the PUDs of the
 * kernel page table into efi_pgd prior to each call.
 *
 * Specially for kexec boot, efi runtime maps in previous kernel should
 * be passed in via setup_data. In that case runtime ranges will be mapped
 * to the same virtual addresses as the first kernel, see
 * kexec_enter_virtual_mode().
 */
static void __init __efi_enter_virtual_mode(void)
{
        int count = 0, pg_shift = 0;
        void *new_memmap = NULL;
        efi_status_t status;
        unsigned long pa;

        efi.systab = NULL;

        if (efi_alloc_page_tables()) {
                pr_err("Failed to allocate EFI page tables\n");
                goto err;
        }

        efi_merge_regions();
        new_memmap = efi_map_regions(&count, &pg_shift);
        if (!new_memmap) {
                pr_err("Error reallocating memory, EFI runtime non-functional!\n");
                goto err;
        }

        pa = __pa(new_memmap);

        /*
         * Unregister the early EFI memmap from efi_init() and install
         * the new EFI memory map that we are about to pass to the
         * firmware via SetVirtualAddressMap().
         */
        efi_memmap_unmap();

        if (efi_memmap_init_late(pa, efi.memmap.desc_size * count)) {
                pr_err("Failed to remap late EFI memory map\n");
                goto err;
        }

        if (efi_enabled(EFI_DBG)) {
                pr_info("EFI runtime memory map:\n");
                efi_print_memmap();
        }

        if (WARN_ON(!efi.systab))
                goto err;

        if (efi_setup_page_tables(pa, 1 << pg_shift))
                goto err;

        efi_sync_low_kernel_mappings();

        status = efi_set_virtual_address_map(efi.memmap.desc_size * count,
                                             efi.memmap.desc_size,
                                             efi.memmap.desc_version,
                                             (efi_memory_desc_t *)pa);
        if (status != EFI_SUCCESS) {
                pr_err("Unable to switch EFI into virtual mode (status=%lx)!\n",
                       status);
                goto err;
        }

        efi_free_boot_services();

        /*
         * Now that EFI is in virtual mode, update the function
         * pointers in the runtime service table to the new virtual addresses.
         *
         * Call EFI services through wrapper functions.
         */
        efi.runtime_version = efi_systab.hdr.revision;

        if (!efi_is_mixed())
                efi_native_runtime_setup();
        else
                efi_thunk_runtime_setup();

        /*
         * Apply more restrictive page table mapping attributes now that
         * SVAM() has been called and the firmware has performed all
         * necessary relocation fixups for the new virtual addresses.
         */
        efi_runtime_update_mappings();

        /* clean DUMMY object */
        efi_delete_dummy_variable();
        return;

err:
        clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);
}

void __init efi_enter_virtual_mode(void)
{
        if (efi_enabled(EFI_PARAVIRT))
                return;

        if (efi_setup)
                kexec_enter_virtual_mode();
        else
                __efi_enter_virtual_mode();

        efi_dump_pagetable();
}

bool efi_is_table_address(unsigned long phys_addr)
{
        unsigned int i;

        if (phys_addr == EFI_INVALID_TABLE_ADDR)
                return false;

        for (i = 0; i < ARRAY_SIZE(efi_tables); i++)
                if (*(efi_tables[i]) == phys_addr)
                        return true;

        return false;

}