x86: modify write_ldt function

[deliverable/linux.git] / arch / x86 / kernel / efi_32.c

/*
 * Extensible Firmware Interface
 *
 * 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>
 *
 * 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.
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/types.h>
#include <linux/time.h>
#include <linux/spinlock.h>
#include <linux/bootmem.h>
#include <linux/ioport.h>
#include <linux/module.h>
#include <linux/efi.h>
#include <linux/kexec.h>

#include <asm/setup.h>
#include <asm/io.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/processor.h>
#include <asm/desc.h>
#include <asm/tlbflush.h>

#define EFI_DEBUG       0
#define PFX             "EFI: "

extern efi_status_t asmlinkage efi_call_phys(void *, ...);

struct efi efi;
EXPORT_SYMBOL(efi);
static struct efi efi_phys;
struct efi_memory_map memmap;

/*
 * We require an early boot_ioremap mapping mechanism initially
 */
extern void * boot_ioremap(unsigned long, unsigned long);

/*
 * To make EFI call EFI runtime service in physical addressing mode we need
 * prelog/epilog before/after the invocation to disable interrupt, to
 * claim EFI runtime service handler exclusively and to duplicate a memory in
 * low memory space say 0 - 3G.
 */

static unsigned long efi_rt_eflags;
static DEFINE_SPINLOCK(efi_rt_lock);
static pgd_t efi_bak_pg_dir_pointer[2];

static void efi_call_phys_prelog(void) __acquires(efi_rt_lock)
{
        unsigned long cr4;
        unsigned long temp;
        struct desc_ptr gdt_descr;

        spin_lock(&efi_rt_lock);
        local_irq_save(efi_rt_eflags);

        /*
         * If I don't have PSE, I should just duplicate two entries in page
         * directory. If I have PSE, I just need to duplicate one entry in
         * page directory.
         */
        cr4 = read_cr4();

        if (cr4 & X86_CR4_PSE) {
                efi_bak_pg_dir_pointer[0].pgd =
                    swapper_pg_dir[pgd_index(0)].pgd;
                swapper_pg_dir[0].pgd =
                    swapper_pg_dir[pgd_index(PAGE_OFFSET)].pgd;
        } else {
                efi_bak_pg_dir_pointer[0].pgd =
                    swapper_pg_dir[pgd_index(0)].pgd;
                efi_bak_pg_dir_pointer[1].pgd =
                    swapper_pg_dir[pgd_index(0x400000)].pgd;
                swapper_pg_dir[pgd_index(0)].pgd =
                    swapper_pg_dir[pgd_index(PAGE_OFFSET)].pgd;
                temp = PAGE_OFFSET + 0x400000;
                swapper_pg_dir[pgd_index(0x400000)].pgd =
                    swapper_pg_dir[pgd_index(temp)].pgd;
        }

        /*
         * After the lock is released, the original page table is restored.
         */
        local_flush_tlb();

        gdt_descr.address = __pa(get_cpu_gdt_table(0));
        gdt_descr.size = GDT_SIZE - 1;
        load_gdt(&gdt_descr);
}

static void efi_call_phys_epilog(void) __releases(efi_rt_lock)
{
        unsigned long cr4;
        struct desc_ptr gdt_descr;

        gdt_descr.address = (unsigned long)get_cpu_gdt_table(0);
        gdt_descr.size = GDT_SIZE - 1;
        load_gdt(&gdt_descr);

        cr4 = read_cr4();

        if (cr4 & X86_CR4_PSE) {
                swapper_pg_dir[pgd_index(0)].pgd =
                    efi_bak_pg_dir_pointer[0].pgd;
        } else {
                swapper_pg_dir[pgd_index(0)].pgd =
                    efi_bak_pg_dir_pointer[0].pgd;
                swapper_pg_dir[pgd_index(0x400000)].pgd =
                    efi_bak_pg_dir_pointer[1].pgd;
        }

        /*
         * After the lock is released, the original page table is restored.
         */
        local_flush_tlb();

        local_irq_restore(efi_rt_eflags);
        spin_unlock(&efi_rt_lock);
}

static efi_status_t
phys_efi_set_virtual_address_map(unsigned long memory_map_size,
                                 unsigned long descriptor_size,
                                 u32 descriptor_version,
                                 efi_memory_desc_t *virtual_map)
{
        efi_status_t status;

        efi_call_phys_prelog();
        status = efi_call_phys(efi_phys.set_virtual_address_map,
                                     memory_map_size, descriptor_size,
                                     descriptor_version, virtual_map);
        efi_call_phys_epilog();
        return status;
}

static efi_status_t
phys_efi_get_time(efi_time_t *tm, efi_time_cap_t *tc)
{
        efi_status_t status;

        efi_call_phys_prelog();
        status = efi_call_phys(efi_phys.get_time, tm, tc);
        efi_call_phys_epilog();
        return status;
}

inline int efi_set_rtc_mmss(unsigned long nowtime)
{
        int real_seconds, real_minutes;
        efi_status_t    status;
        efi_time_t      eft;
        efi_time_cap_t  cap;

        spin_lock(&efi_rt_lock);
        status = efi.get_time(&eft, &cap);
        spin_unlock(&efi_rt_lock);
        if (status != EFI_SUCCESS)
                panic("Ooops, efitime: can't read time!\n");
        real_seconds = nowtime % 60;
        real_minutes = nowtime / 60;

        if (((abs(real_minutes - eft.minute) + 15)/30) & 1)
                real_minutes += 30;
        real_minutes %= 60;

        eft.minute = real_minutes;
        eft.second = real_seconds;

        if (status != EFI_SUCCESS) {
                printk("Ooops: efitime: can't read time!\n");
                return -1;
        }
        return 0;
}
/*
 * This is used during kernel init before runtime
 * services have been remapped and also during suspend, therefore,
 * we'll need to call both in physical and virtual modes.
 */
inline unsigned long efi_get_time(void)
{
        efi_status_t status;
        efi_time_t eft;
        efi_time_cap_t cap;

        if (efi.get_time) {
                /* if we are in virtual mode use remapped function */
                status = efi.get_time(&eft, &cap);
        } else {
                /* we are in physical mode */
                status = phys_efi_get_time(&eft, &cap);
        }

        if (status != EFI_SUCCESS)
                printk("Oops: efitime: can't read time status: 0x%lx\n",status);

        return mktime(eft.year, eft.month, eft.day, eft.hour,
                        eft.minute, eft.second);
}

int is_available_memory(efi_memory_desc_t * md)
{
        if (!(md->attribute & EFI_MEMORY_WB))
                return 0;

        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:
                        return 1;
        }
        return 0;
}

/*
 * We need to map the EFI memory map again after paging_init().
 */
void __init efi_map_memmap(void)
{
        memmap.map = NULL;

        memmap.map = bt_ioremap((unsigned long) memmap.phys_map,
                        (memmap.nr_map * memmap.desc_size));
        if (memmap.map == NULL)
                printk(KERN_ERR PFX "Could not remap the EFI memmap!\n");

        memmap.map_end = memmap.map + (memmap.nr_map * memmap.desc_size);
}

#if EFI_DEBUG
static void __init print_efi_memmap(void)
{
        efi_memory_desc_t *md;
        void *p;
        int i;

        for (p = memmap.map, i = 0; p < memmap.map_end; p += memmap.desc_size, i++) {
                md = p;
                printk(KERN_INFO "mem%02u: type=%u, attr=0x%llx, "
                        "range=[0x%016llx-0x%016llx) (%lluMB)\n",
                        i, md->type, md->attribute, md->phys_addr,
                        md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT),
                        (md->num_pages >> (20 - EFI_PAGE_SHIFT)));
        }
}
#endif  /*  EFI_DEBUG  */

/*
 * Walks the EFI memory map and calls CALLBACK once for each EFI
 * memory descriptor that has memory that is available for kernel use.
 */
void efi_memmap_walk(efi_freemem_callback_t callback, void *arg)
{
        int prev_valid = 0;
        struct range {
                unsigned long start;
                unsigned long end;
        } uninitialized_var(prev), curr;
        efi_memory_desc_t *md;
        unsigned long start, end;
        void *p;

        for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
                md = p;

                if ((md->num_pages == 0) || (!is_available_memory(md)))
                        continue;

                curr.start = md->phys_addr;
                curr.end = curr.start + (md->num_pages << EFI_PAGE_SHIFT);

                if (!prev_valid) {
                        prev = curr;
                        prev_valid = 1;
                } else {
                        if (curr.start < prev.start)
                                printk(KERN_INFO PFX "Unordered memory map\n");
                        if (prev.end == curr.start)
                                prev.end = curr.end;
                        else {
                                start =
                                    (unsigned long) (PAGE_ALIGN(prev.start));
                                end = (unsigned long) (prev.end & PAGE_MASK);
                                if ((end > start)
                                    && (*callback) (start, end, arg) < 0)
                                        return;
                                prev = curr;
                        }
                }
        }
        if (prev_valid) {
                start = (unsigned long) PAGE_ALIGN(prev.start);
                end = (unsigned long) (prev.end & PAGE_MASK);
                if (end > start)
                        (*callback) (start, end, arg);
        }
}

void __init efi_init(void)
{
        efi_config_table_t *config_tables;
        efi_runtime_services_t *runtime;
        efi_char16_t *c16;
        char vendor[100] = "unknown";
        unsigned long num_config_tables;
        int i = 0;

        memset(&efi, 0, sizeof(efi) );
        memset(&efi_phys, 0, sizeof(efi_phys));

        efi_phys.systab =
                (efi_system_table_t *)boot_params.efi_info.efi_systab;
        memmap.phys_map = (void *)boot_params.efi_info.efi_memmap;
        memmap.nr_map = boot_params.efi_info.efi_memmap_size/
                boot_params.efi_info.efi_memdesc_size;
        memmap.desc_version = boot_params.efi_info.efi_memdesc_version;
        memmap.desc_size = boot_params.efi_info.efi_memdesc_size;

        efi.systab = (efi_system_table_t *)
                boot_ioremap((unsigned long) efi_phys.systab,
                        sizeof(efi_system_table_t));
        /*
         * Verify the EFI Table
         */
        if (efi.systab == NULL)
                printk(KERN_ERR PFX "Woah! Couldn't map the EFI system table.\n");
        if (efi.systab->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE)
                printk(KERN_ERR PFX "Woah! EFI system table signature incorrect\n");
        if ((efi.systab->hdr.revision >> 16) == 0)
                printk(KERN_ERR PFX "Warning: EFI system table version "
                       "%d.%02d, expected 1.00 or greater\n",
                       efi.systab->hdr.revision >> 16,
                       efi.systab->hdr.revision & 0xffff);

        /*
         * Grab some details from the system table
         */
        num_config_tables = efi.systab->nr_tables;
        config_tables = (efi_config_table_t *)efi.systab->tables;
        runtime = efi.systab->runtime;

        /*
         * Show what we know for posterity
         */
        c16 = (efi_char16_t *) boot_ioremap(efi.systab->fw_vendor, 2);
        if (c16) {
                for (i = 0; i < (sizeof(vendor) - 1) && *c16; ++i)
                        vendor[i] = *c16++;
                vendor[i] = '\0';
        } else
                printk(KERN_ERR PFX "Could not map the firmware vendor!\n");

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

        /*
         * Let's see what config tables the firmware passed to us.
         */
        config_tables = (efi_config_table_t *)
                                boot_ioremap((unsigned long) config_tables,
                                num_config_tables * sizeof(efi_config_table_t));

        if (config_tables == NULL)
                printk(KERN_ERR PFX "Could not map EFI Configuration Table!\n");

        efi.mps        = EFI_INVALID_TABLE_ADDR;
        efi.acpi       = EFI_INVALID_TABLE_ADDR;
        efi.acpi20     = EFI_INVALID_TABLE_ADDR;
        efi.smbios     = EFI_INVALID_TABLE_ADDR;
        efi.sal_systab = EFI_INVALID_TABLE_ADDR;
        efi.boot_info  = EFI_INVALID_TABLE_ADDR;
        efi.hcdp       = EFI_INVALID_TABLE_ADDR;
        efi.uga        = EFI_INVALID_TABLE_ADDR;

        for (i = 0; i < num_config_tables; i++) {
                if (efi_guidcmp(config_tables[i].guid, MPS_TABLE_GUID) == 0) {
                        efi.mps = config_tables[i].table;
                        printk(KERN_INFO " MPS=0x%lx ", config_tables[i].table);
                } else
                    if (efi_guidcmp(config_tables[i].guid, ACPI_20_TABLE_GUID) == 0) {
                        efi.acpi20 = config_tables[i].table;
                        printk(KERN_INFO " ACPI 2.0=0x%lx ", config_tables[i].table);
                } else
                    if (efi_guidcmp(config_tables[i].guid, ACPI_TABLE_GUID) == 0) {
                        efi.acpi = config_tables[i].table;
                        printk(KERN_INFO " ACPI=0x%lx ", config_tables[i].table);
                } else
                    if (efi_guidcmp(config_tables[i].guid, SMBIOS_TABLE_GUID) == 0) {
                        efi.smbios = config_tables[i].table;
                        printk(KERN_INFO " SMBIOS=0x%lx ", config_tables[i].table);
                } else
                    if (efi_guidcmp(config_tables[i].guid, HCDP_TABLE_GUID) == 0) {
                        efi.hcdp = config_tables[i].table;
                        printk(KERN_INFO " HCDP=0x%lx ", config_tables[i].table);
                } else
                    if (efi_guidcmp(config_tables[i].guid, UGA_IO_PROTOCOL_GUID) == 0) {
                        efi.uga = config_tables[i].table;
                        printk(KERN_INFO " UGA=0x%lx ", config_tables[i].table);
                }
        }
        printk("\n");

        /*
         * Check out the runtime services table. We need to map
         * the runtime services table so that we can grab the physical
         * address of several of the EFI runtime functions, needed to
         * set the firmware into virtual mode.
         */

        runtime = (efi_runtime_services_t *) boot_ioremap((unsigned long)
                                                runtime,
                                                sizeof(efi_runtime_services_t));
        if (runtime != NULL) {
                /*
                 * We will only need *early* access to the following
                 * two EFI runtime services before set_virtual_address_map
                 * is invoked.
                 */
                efi_phys.get_time = (efi_get_time_t *) runtime->get_time;
                efi_phys.set_virtual_address_map =
                        (efi_set_virtual_address_map_t *)
                                runtime->set_virtual_address_map;
        } else
                printk(KERN_ERR PFX "Could not map the runtime service table!\n");

        /* Map the EFI memory map for use until paging_init() */
        memmap.map = boot_ioremap(boot_params.efi_info.efi_memmap,
                                  boot_params.efi_info.efi_memmap_size);
        if (memmap.map == NULL)
                printk(KERN_ERR PFX "Could not map the EFI memory map!\n");

        memmap.map_end = memmap.map + (memmap.nr_map * memmap.desc_size);

#if EFI_DEBUG
        print_efi_memmap();
#endif
}

static inline void __init check_range_for_systab(efi_memory_desc_t *md)
{
        if (((unsigned long)md->phys_addr <= (unsigned long)efi_phys.systab) &&
                ((unsigned long)efi_phys.systab < md->phys_addr +
                ((unsigned long)md->num_pages << EFI_PAGE_SHIFT))) {
                unsigned long addr;

                addr = md->virt_addr - md->phys_addr +
                        (unsigned long)efi_phys.systab;
                efi.systab = (efi_system_table_t *)addr;
        }
}

/*
 * Wrap all the virtual calls in a way that forces the parameters on the stack.
 */

#define efi_call_virt(f, args...) \
     ((efi_##f##_t __attribute__((regparm(0)))*)efi.systab->runtime->f)(args)

static efi_status_t virt_efi_get_time(efi_time_t *tm, efi_time_cap_t *tc)
{
        return efi_call_virt(get_time, tm, tc);
}

static efi_status_t virt_efi_set_time (efi_time_t *tm)
{
        return efi_call_virt(set_time, tm);
}

static efi_status_t virt_efi_get_wakeup_time (efi_bool_t *enabled,
                                              efi_bool_t *pending,
                                              efi_time_t *tm)
{
        return efi_call_virt(get_wakeup_time, enabled, pending, tm);
}

static efi_status_t virt_efi_set_wakeup_time (efi_bool_t enabled,
                                              efi_time_t *tm)
{
        return efi_call_virt(set_wakeup_time, enabled, tm);
}

static efi_status_t virt_efi_get_variable (efi_char16_t *name,
                                           efi_guid_t *vendor, u32 *attr,
                                           unsigned long *data_size, void *data)
{
        return efi_call_virt(get_variable, name, vendor, attr, data_size, data);
}

static efi_status_t virt_efi_get_next_variable (unsigned long *name_size,
                                                efi_char16_t *name,
                                                efi_guid_t *vendor)
{
        return efi_call_virt(get_next_variable, name_size, name, vendor);
}

static efi_status_t virt_efi_set_variable (efi_char16_t *name,
                                           efi_guid_t *vendor,
                                           unsigned long attr,
                                           unsigned long data_size, void *data)
{
        return efi_call_virt(set_variable, name, vendor, attr, data_size, data);
}

static efi_status_t virt_efi_get_next_high_mono_count (u32 *count)
{
        return efi_call_virt(get_next_high_mono_count, count);
}

static void virt_efi_reset_system (int reset_type, efi_status_t status,
                                   unsigned long data_size,
                                   efi_char16_t *data)
{
        efi_call_virt(reset_system, reset_type, status, data_size, data);
}

/*
 * This function will switch the EFI runtime services to virtual mode.
 * Essentially, look through the EFI memmap and map every region that
 * has the runtime attribute bit set in its memory descriptor and update
 * that memory descriptor with the virtual address obtained from ioremap().
 * This enables the runtime services to be called without having to
 * thunk back into physical mode for every invocation.
 */

void __init efi_enter_virtual_mode(void)
{
        efi_memory_desc_t *md;
        efi_status_t status;
        void *p;

        efi.systab = NULL;

        for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
                md = p;

                if (!(md->attribute & EFI_MEMORY_RUNTIME))
                        continue;

                md->virt_addr = (unsigned long)ioremap(md->phys_addr,
                        md->num_pages << EFI_PAGE_SHIFT);
                if (!(unsigned long)md->virt_addr) {
                        printk(KERN_ERR PFX "ioremap of 0x%lX failed\n",
                                (unsigned long)md->phys_addr);
                }
                /* update the virtual address of the EFI system table */
                check_range_for_systab(md);
        }

        BUG_ON(!efi.systab);

        status = phys_efi_set_virtual_address_map(
                        memmap.desc_size * memmap.nr_map,
                        memmap.desc_size,
                        memmap.desc_version,
                        memmap.phys_map);

        if (status != EFI_SUCCESS) {
                printk (KERN_ALERT "You are screwed! "
                        "Unable to switch EFI into virtual mode "
                        "(status=%lx)\n", status);
                panic("EFI call to SetVirtualAddressMap() failed!");
        }

        /*
         * Now that EFI is in virtual mode, update the function
         * pointers in the runtime service table to the new virtual addresses.
         */

        efi.get_time = virt_efi_get_time;
        efi.set_time = virt_efi_set_time;
        efi.get_wakeup_time = virt_efi_get_wakeup_time;
        efi.set_wakeup_time = virt_efi_set_wakeup_time;
        efi.get_variable = virt_efi_get_variable;
        efi.get_next_variable = virt_efi_get_next_variable;
        efi.set_variable = virt_efi_set_variable;
        efi.get_next_high_mono_count = virt_efi_get_next_high_mono_count;
        efi.reset_system = virt_efi_reset_system;
}

void __init
efi_initialize_iomem_resources(struct resource *code_resource,
                               struct resource *data_resource,
                               struct resource *bss_resource)
{
        struct resource *res;
        efi_memory_desc_t *md;
        void *p;

        for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
                md = p;

                if ((md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT)) >
                    0x100000000ULL)
                        continue;
                res = kzalloc(sizeof(struct resource), GFP_ATOMIC);
                switch (md->type) {
                case EFI_RESERVED_TYPE:
                        res->name = "Reserved Memory";
                        break;
                case EFI_LOADER_CODE:
                        res->name = "Loader Code";
                        break;
                case EFI_LOADER_DATA:
                        res->name = "Loader Data";
                        break;
                case EFI_BOOT_SERVICES_DATA:
                        res->name = "BootServices Data";
                        break;
                case EFI_BOOT_SERVICES_CODE:
                        res->name = "BootServices Code";
                        break;
                case EFI_RUNTIME_SERVICES_CODE:
                        res->name = "Runtime Service Code";
                        break;
                case EFI_RUNTIME_SERVICES_DATA:
                        res->name = "Runtime Service Data";
                        break;
                case EFI_CONVENTIONAL_MEMORY:
                        res->name = "Conventional Memory";
                        break;
                case EFI_UNUSABLE_MEMORY:
                        res->name = "Unusable Memory";
                        break;
                case EFI_ACPI_RECLAIM_MEMORY:
                        res->name = "ACPI Reclaim";
                        break;
                case EFI_ACPI_MEMORY_NVS:
                        res->name = "ACPI NVS";
                        break;
                case EFI_MEMORY_MAPPED_IO:
                        res->name = "Memory Mapped IO";
                        break;
                case EFI_MEMORY_MAPPED_IO_PORT_SPACE:
                        res->name = "Memory Mapped IO Port Space";
                        break;
                default:
                        res->name = "Reserved";
                        break;
                }
                res->start = md->phys_addr;
                res->end = res->start + ((md->num_pages << EFI_PAGE_SHIFT) - 1);
                res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
                if (request_resource(&iomem_resource, res) < 0)
                        printk(KERN_ERR PFX "Failed to allocate res %s : "
                                "0x%llx-0x%llx\n", res->name,
                                (unsigned long long)res->start,
                                (unsigned long long)res->end);
                /*
                 * We don't know which region contains kernel data so we try
                 * it repeatedly and let the resource manager test it.
                 */
                if (md->type == EFI_CONVENTIONAL_MEMORY) {
                        request_resource(res, code_resource);
                        request_resource(res, data_resource);
                        request_resource(res, bss_resource);
#ifdef CONFIG_KEXEC
                        request_resource(res, &crashk_res);
#endif
                }
        }
}

/*
 * Convenience functions to obtain memory types and attributes
 */

u32 efi_mem_type(unsigned long phys_addr)
{
        efi_memory_desc_t *md;
        void *p;

        for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
                md = p;
                if ((md->phys_addr <= phys_addr) && (phys_addr <
                        (md->phys_addr + (md-> num_pages << EFI_PAGE_SHIFT)) ))
                        return md->type;
        }
        return 0;
}

u64 efi_mem_attributes(unsigned long phys_addr)
{
        efi_memory_desc_t *md;
        void *p;

        for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
                md = p;
                if ((md->phys_addr <= phys_addr) && (phys_addr <
                        (md->phys_addr + (md-> num_pages << EFI_PAGE_SHIFT)) ))
                        return md->attribute;
        }
        return 0;
}