[PATCH] briq_panel: read() and write() get __user pointers, damnit

[linux-2.6/verdex.git] / arch / powerpc / kernel / vdso.c

/*
 *    Copyright (C) 2004 Benjamin Herrenschmidt, IBM Corp.
 *                       <benh@kernel.crashing.org>
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version
 *  2 of the License, or (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/slab.h>
#include <linux/user.h>
#include <linux/elf.h>
#include <linux/security.h>
#include <linux/bootmem.h>

#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/processor.h>
#include <asm/mmu.h>
#include <asm/mmu_context.h>
#include <asm/lmb.h>
#include <asm/machdep.h>
#include <asm/cputable.h>
#include <asm/sections.h>
#include <asm/firmware.h>
#include <asm/vdso.h>
#include <asm/vdso_datapage.h>

#undef DEBUG

#ifdef DEBUG
#define DBG(fmt...) printk(fmt)
#else
#define DBG(fmt...)
#endif

/* Max supported size for symbol names */
#define MAX_SYMNAME     64

extern char vdso32_start, vdso32_end;
static void *vdso32_kbase = &vdso32_start;
unsigned int vdso32_pages;
unsigned long vdso32_sigtramp;
unsigned long vdso32_rt_sigtramp;

#ifdef CONFIG_PPC64
extern char vdso64_start, vdso64_end;
static void *vdso64_kbase = &vdso64_start;
unsigned int vdso64_pages;
unsigned long vdso64_rt_sigtramp;
#endif /* CONFIG_PPC64 */

/*
 * The vdso data page (aka. systemcfg for old ppc64 fans) is here.
 * Once the early boot kernel code no longer needs to muck around
 * with it, it will become dynamically allocated
 */
static union {
        struct vdso_data        data;
        u8                      page[PAGE_SIZE];
} vdso_data_store __attribute__((__section__(".data.page_aligned")));
struct vdso_data *vdso_data = &vdso_data_store.data;

/* Format of the patch table */
struct vdso_patch_def
{
        unsigned long   ftr_mask, ftr_value;
        const char      *gen_name;
        const char      *fix_name;
};

/* Table of functions to patch based on the CPU type/revision
 *
 * Currently, we only change sync_dicache to do nothing on processors
 * with a coherent icache
 */
static struct vdso_patch_def vdso_patches[] = {
        {
                CPU_FTR_COHERENT_ICACHE, CPU_FTR_COHERENT_ICACHE,
                "__kernel_sync_dicache", "__kernel_sync_dicache_p5"
        },
        {
                CPU_FTR_USE_TB, 0,
                "__kernel_gettimeofday", NULL
        },
};

/*
 * Some infos carried around for each of them during parsing at
 * boot time.
 */
struct lib32_elfinfo
{
        Elf32_Ehdr      *hdr;           /* ptr to ELF */
        Elf32_Sym       *dynsym;        /* ptr to .dynsym section */
        unsigned long   dynsymsize;     /* size of .dynsym section */
        char            *dynstr;        /* ptr to .dynstr section */
        unsigned long   text;           /* offset of .text section in .so */
};

struct lib64_elfinfo
{
        Elf64_Ehdr      *hdr;
        Elf64_Sym       *dynsym;
        unsigned long   dynsymsize;
        char            *dynstr;
        unsigned long   text;
};


#ifdef __DEBUG
static void dump_one_vdso_page(struct page *pg, struct page *upg)
{
        printk("kpg: %p (c:%d,f:%08lx)", __va(page_to_pfn(pg) << PAGE_SHIFT),
               page_count(pg),
               pg->flags);
        if (upg/* && pg != upg*/) {
                printk(" upg: %p (c:%d,f:%08lx)", __va(page_to_pfn(upg)
                                                       << PAGE_SHIFT),
                       page_count(upg),
                       upg->flags);
        }
        printk("\n");
}

static void dump_vdso_pages(struct vm_area_struct * vma)
{
        int i;

        if (!vma || test_thread_flag(TIF_32BIT)) {
                printk("vDSO32 @ %016lx:\n", (unsigned long)vdso32_kbase);
                for (i=0; i<vdso32_pages; i++) {
                        struct page *pg = virt_to_page(vdso32_kbase +
                                                       i*PAGE_SIZE);
                        struct page *upg = (vma && vma->vm_mm) ?
                                follow_page(vma, vma->vm_start + i*PAGE_SIZE, 0)
                                : NULL;
                        dump_one_vdso_page(pg, upg);
                }
        }
        if (!vma || !test_thread_flag(TIF_32BIT)) {
                printk("vDSO64 @ %016lx:\n", (unsigned long)vdso64_kbase);
                for (i=0; i<vdso64_pages; i++) {
                        struct page *pg = virt_to_page(vdso64_kbase +
                                                       i*PAGE_SIZE);
                        struct page *upg = (vma && vma->vm_mm) ?
                                follow_page(vma, vma->vm_start + i*PAGE_SIZE, 0)
                                : NULL;
                        dump_one_vdso_page(pg, upg);
                }
        }
}
#endif /* DEBUG */

/*
 * Keep a dummy vma_close for now, it will prevent VMA merging.
 */
static void vdso_vma_close(struct vm_area_struct * vma)
{
}

/*
 * Our nopage() function, maps in the actual vDSO kernel pages, they will
 * be mapped read-only by do_no_page(), and eventually COW'ed, either
 * right away for an initial write access, or by do_wp_page().
 */
static struct page * vdso_vma_nopage(struct vm_area_struct * vma,
                                     unsigned long address, int *type)
{
        unsigned long offset = address - vma->vm_start;
        struct page *pg;
#ifdef CONFIG_PPC64
        void *vbase = (vma->vm_mm->task_size > TASK_SIZE_USER32) ?
                vdso64_kbase : vdso32_kbase;
#else
        void *vbase = vdso32_kbase;
#endif

        DBG("vdso_vma_nopage(current: %s, address: %016lx, off: %lx)\n",
            current->comm, address, offset);

        if (address < vma->vm_start || address > vma->vm_end)
                return NOPAGE_SIGBUS;

        /*
         * Last page is systemcfg.
         */
        if ((vma->vm_end - address) <= PAGE_SIZE)
                pg = virt_to_page(vdso_data);
        else
                pg = virt_to_page(vbase + offset);

        get_page(pg);
        DBG(" ->page count: %d\n", page_count(pg));

        return pg;
}

static struct vm_operations_struct vdso_vmops = {
        .close  = vdso_vma_close,
        .nopage = vdso_vma_nopage,
};

/*
 * This is called from binfmt_elf, we create the special vma for the
 * vDSO and insert it into the mm struct tree
 */
int arch_setup_additional_pages(struct linux_binprm *bprm,
                                int executable_stack)
{
        struct mm_struct *mm = current->mm;
        struct vm_area_struct *vma;
        unsigned long vdso_pages;
        unsigned long vdso_base;
        int rc;

#ifdef CONFIG_PPC64
        if (test_thread_flag(TIF_32BIT)) {
                vdso_pages = vdso32_pages;
                vdso_base = VDSO32_MBASE;
        } else {
                vdso_pages = vdso64_pages;
                vdso_base = VDSO64_MBASE;
        }
#else
        vdso_pages = vdso32_pages;
        vdso_base = VDSO32_MBASE;
#endif

        current->mm->context.vdso_base = 0;

        /* vDSO has a problem and was disabled, just don't "enable" it for the
         * process
         */
        if (vdso_pages == 0)
                return 0;
        /* Add a page to the vdso size for the data page */
        vdso_pages ++;

        /*
         * pick a base address for the vDSO in process space. We try to put it
         * at vdso_base which is the "natural" base for it, but we might fail
         * and end up putting it elsewhere.
         */
        down_write(&mm->mmap_sem);
        vdso_base = get_unmapped_area(NULL, vdso_base,
                                      vdso_pages << PAGE_SHIFT, 0, 0);
        if (IS_ERR_VALUE(vdso_base)) {
                rc = vdso_base;
                goto fail_mmapsem;
        }


        /* Allocate a VMA structure and fill it up */
        vma = kmem_cache_zalloc(vm_area_cachep, SLAB_KERNEL);
        if (vma == NULL) {
                rc = -ENOMEM;
                goto fail_mmapsem;
        }
        vma->vm_mm = mm;
        vma->vm_start = vdso_base;
        vma->vm_end = vma->vm_start + (vdso_pages << PAGE_SHIFT);

        /*
         * our vma flags don't have VM_WRITE so by default, the process isn't
         * allowed to write those pages.
         * gdb can break that with ptrace interface, and thus trigger COW on
         * those pages but it's then your responsibility to never do that on
         * the "data" page of the vDSO or you'll stop getting kernel updates
         * and your nice userland gettimeofday will be totally dead.
         * It's fine to use that for setting breakpoints in the vDSO code
         * pages though
         */
        vma->vm_flags = VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC;
        vma->vm_flags |= mm->def_flags;
        vma->vm_page_prot = protection_map[vma->vm_flags & 0x7];
        vma->vm_ops = &vdso_vmops;

        /* Insert new VMA */
        rc = insert_vm_struct(mm, vma);
        if (rc)
                goto fail_vma;

        /* Put vDSO base into mm struct and account for memory usage */
        current->mm->context.vdso_base = vdso_base;
        mm->total_vm += (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
        up_write(&mm->mmap_sem);
        return 0;

 fail_vma:
        kmem_cache_free(vm_area_cachep, vma);
 fail_mmapsem:
        up_write(&mm->mmap_sem);
        return rc;
}

const char *arch_vma_name(struct vm_area_struct *vma)
{
        if (vma->vm_mm && vma->vm_start == vma->vm_mm->context.vdso_base)
                return "[vdso]";
        return NULL;
}



static void * __init find_section32(Elf32_Ehdr *ehdr, const char *secname,
                                  unsigned long *size)
{
        Elf32_Shdr *sechdrs;
        unsigned int i;
        char *secnames;

        /* Grab section headers and strings so we can tell who is who */
        sechdrs = (void *)ehdr + ehdr->e_shoff;
        secnames = (void *)ehdr + sechdrs[ehdr->e_shstrndx].sh_offset;

        /* Find the section they want */
        for (i = 1; i < ehdr->e_shnum; i++) {
                if (strcmp(secnames+sechdrs[i].sh_name, secname) == 0) {
                        if (size)
                                *size = sechdrs[i].sh_size;
                        return (void *)ehdr + sechdrs[i].sh_offset;
                }
        }
        *size = 0;
        return NULL;
}

static Elf32_Sym * __init find_symbol32(struct lib32_elfinfo *lib,
                                        const char *symname)
{
        unsigned int i;
        char name[MAX_SYMNAME], *c;

        for (i = 0; i < (lib->dynsymsize / sizeof(Elf32_Sym)); i++) {
                if (lib->dynsym[i].st_name == 0)
                        continue;
                strlcpy(name, lib->dynstr + lib->dynsym[i].st_name,
                        MAX_SYMNAME);
                c = strchr(name, '@');
                if (c)
                        *c = 0;
                if (strcmp(symname, name) == 0)
                        return &lib->dynsym[i];
        }
        return NULL;
}

/* Note that we assume the section is .text and the symbol is relative to
 * the library base
 */
static unsigned long __init find_function32(struct lib32_elfinfo *lib,
                                            const char *symname)
{
        Elf32_Sym *sym = find_symbol32(lib, symname);

        if (sym == NULL) {
                printk(KERN_WARNING "vDSO32: function %s not found !\n",
                       symname);
                return 0;
        }
        return sym->st_value - VDSO32_LBASE;
}

static int vdso_do_func_patch32(struct lib32_elfinfo *v32,
                                struct lib64_elfinfo *v64,
                                const char *orig, const char *fix)
{
        Elf32_Sym *sym32_gen, *sym32_fix;

        sym32_gen = find_symbol32(v32, orig);
        if (sym32_gen == NULL) {
                printk(KERN_ERR "vDSO32: Can't find symbol %s !\n", orig);
                return -1;
        }
        if (fix == NULL) {
                sym32_gen->st_name = 0;
                return 0;
        }
        sym32_fix = find_symbol32(v32, fix);
        if (sym32_fix == NULL) {
                printk(KERN_ERR "vDSO32: Can't find symbol %s !\n", fix);
                return -1;
        }
        sym32_gen->st_value = sym32_fix->st_value;
        sym32_gen->st_size = sym32_fix->st_size;
        sym32_gen->st_info = sym32_fix->st_info;
        sym32_gen->st_other = sym32_fix->st_other;
        sym32_gen->st_shndx = sym32_fix->st_shndx;

        return 0;
}


#ifdef CONFIG_PPC64

static void * __init find_section64(Elf64_Ehdr *ehdr, const char *secname,
                                  unsigned long *size)
{
        Elf64_Shdr *sechdrs;
        unsigned int i;
        char *secnames;

        /* Grab section headers and strings so we can tell who is who */
        sechdrs = (void *)ehdr + ehdr->e_shoff;
        secnames = (void *)ehdr + sechdrs[ehdr->e_shstrndx].sh_offset;

        /* Find the section they want */
        for (i = 1; i < ehdr->e_shnum; i++) {
                if (strcmp(secnames+sechdrs[i].sh_name, secname) == 0) {
                        if (size)
                                *size = sechdrs[i].sh_size;
                        return (void *)ehdr + sechdrs[i].sh_offset;
                }
        }
        if (size)
                *size = 0;
        return NULL;
}

static Elf64_Sym * __init find_symbol64(struct lib64_elfinfo *lib,
                                        const char *symname)
{
        unsigned int i;
        char name[MAX_SYMNAME], *c;

        for (i = 0; i < (lib->dynsymsize / sizeof(Elf64_Sym)); i++) {
                if (lib->dynsym[i].st_name == 0)
                        continue;
                strlcpy(name, lib->dynstr + lib->dynsym[i].st_name,
                        MAX_SYMNAME);
                c = strchr(name, '@');
                if (c)
                        *c = 0;
                if (strcmp(symname, name) == 0)
                        return &lib->dynsym[i];
        }
        return NULL;
}

/* Note that we assume the section is .text and the symbol is relative to
 * the library base
 */
static unsigned long __init find_function64(struct lib64_elfinfo *lib,
                                            const char *symname)
{
        Elf64_Sym *sym = find_symbol64(lib, symname);

        if (sym == NULL) {
                printk(KERN_WARNING "vDSO64: function %s not found !\n",
                       symname);
                return 0;
        }
#ifdef VDS64_HAS_DESCRIPTORS
        return *((u64 *)(vdso64_kbase + sym->st_value - VDSO64_LBASE)) -
                VDSO64_LBASE;
#else
        return sym->st_value - VDSO64_LBASE;
#endif
}

static int vdso_do_func_patch64(struct lib32_elfinfo *v32,
                                struct lib64_elfinfo *v64,
                                const char *orig, const char *fix)
{
        Elf64_Sym *sym64_gen, *sym64_fix;

        sym64_gen = find_symbol64(v64, orig);
        if (sym64_gen == NULL) {
                printk(KERN_ERR "vDSO64: Can't find symbol %s !\n", orig);
                return -1;
        }
        if (fix == NULL) {
                sym64_gen->st_name = 0;
                return 0;
        }
        sym64_fix = find_symbol64(v64, fix);
        if (sym64_fix == NULL) {
                printk(KERN_ERR "vDSO64: Can't find symbol %s !\n", fix);
                return -1;
        }
        sym64_gen->st_value = sym64_fix->st_value;
        sym64_gen->st_size = sym64_fix->st_size;
        sym64_gen->st_info = sym64_fix->st_info;
        sym64_gen->st_other = sym64_fix->st_other;
        sym64_gen->st_shndx = sym64_fix->st_shndx;

        return 0;
}

#endif /* CONFIG_PPC64 */


static __init int vdso_do_find_sections(struct lib32_elfinfo *v32,
                                        struct lib64_elfinfo *v64)
{
        void *sect;

        /*
         * Locate symbol tables & text section
         */

        v32->dynsym = find_section32(v32->hdr, ".dynsym", &v32->dynsymsize);
        v32->dynstr = find_section32(v32->hdr, ".dynstr", NULL);
        if (v32->dynsym == NULL || v32->dynstr == NULL) {
                printk(KERN_ERR "vDSO32: required symbol section not found\n");
                return -1;
        }
        sect = find_section32(v32->hdr, ".text", NULL);
        if (sect == NULL) {
                printk(KERN_ERR "vDSO32: the .text section was not found\n");
                return -1;
        }
        v32->text = sect - vdso32_kbase;

#ifdef CONFIG_PPC64
        v64->dynsym = find_section64(v64->hdr, ".dynsym", &v64->dynsymsize);
        v64->dynstr = find_section64(v64->hdr, ".dynstr", NULL);
        if (v64->dynsym == NULL || v64->dynstr == NULL) {
                printk(KERN_ERR "vDSO64: required symbol section not found\n");
                return -1;
        }
        sect = find_section64(v64->hdr, ".text", NULL);
        if (sect == NULL) {
                printk(KERN_ERR "vDSO64: the .text section was not found\n");
                return -1;
        }
        v64->text = sect - vdso64_kbase;
#endif /* CONFIG_PPC64 */

        return 0;
}

static __init void vdso_setup_trampolines(struct lib32_elfinfo *v32,
                                          struct lib64_elfinfo *v64)
{
        /*
         * Find signal trampolines
         */

#ifdef CONFIG_PPC64
        vdso64_rt_sigtramp = find_function64(v64, "__kernel_sigtramp_rt64");
#endif
        vdso32_sigtramp    = find_function32(v32, "__kernel_sigtramp32");
        vdso32_rt_sigtramp = find_function32(v32, "__kernel_sigtramp_rt32");
}

static __init int vdso_fixup_datapage(struct lib32_elfinfo *v32,
                                       struct lib64_elfinfo *v64)
{
        Elf32_Sym *sym32;
#ifdef CONFIG_PPC64
        Elf64_Sym *sym64;

        sym64 = find_symbol64(v64, "__kernel_datapage_offset");
        if (sym64 == NULL) {
                printk(KERN_ERR "vDSO64: Can't find symbol "
                       "__kernel_datapage_offset !\n");
                return -1;
        }
        *((int *)(vdso64_kbase + sym64->st_value - VDSO64_LBASE)) =
                (vdso64_pages << PAGE_SHIFT) -
                (sym64->st_value - VDSO64_LBASE);
#endif /* CONFIG_PPC64 */

        sym32 = find_symbol32(v32, "__kernel_datapage_offset");
        if (sym32 == NULL) {
                printk(KERN_ERR "vDSO32: Can't find symbol "
                       "__kernel_datapage_offset !\n");
                return -1;
        }
        *((int *)(vdso32_kbase + (sym32->st_value - VDSO32_LBASE))) =
                (vdso32_pages << PAGE_SHIFT) -
                (sym32->st_value - VDSO32_LBASE);

        return 0;
}

static __init int vdso_fixup_alt_funcs(struct lib32_elfinfo *v32,
                                       struct lib64_elfinfo *v64)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(vdso_patches); i++) {
                struct vdso_patch_def *patch = &vdso_patches[i];
                int match = (cur_cpu_spec->cpu_features & patch->ftr_mask)
                        == patch->ftr_value;
                if (!match)
                        continue;

                DBG("replacing %s with %s...\n", patch->gen_name,
                    patch->fix_name ? "NONE" : patch->fix_name);

                /*
                 * Patch the 32 bits and 64 bits symbols. Note that we do not
                 * patch the "." symbol on 64 bits.
                 * It would be easy to do, but doesn't seem to be necessary,
                 * patching the OPD symbol is enough.
                 */
                vdso_do_func_patch32(v32, v64, patch->gen_name,
                                     patch->fix_name);
#ifdef CONFIG_PPC64
                vdso_do_func_patch64(v32, v64, patch->gen_name,
                                     patch->fix_name);
#endif /* CONFIG_PPC64 */
        }

        return 0;
}


static __init int vdso_setup(void)
{
        struct lib32_elfinfo    v32;
        struct lib64_elfinfo    v64;

        v32.hdr = vdso32_kbase;
#ifdef CONFIG_PPC64
        v64.hdr = vdso64_kbase;
#endif
        if (vdso_do_find_sections(&v32, &v64))
                return -1;

        if (vdso_fixup_datapage(&v32, &v64))
                return -1;

        if (vdso_fixup_alt_funcs(&v32, &v64))
                return -1;

        vdso_setup_trampolines(&v32, &v64);

        return 0;
}

/*
 * Called from setup_arch to initialize the bitmap of available
 * syscalls in the systemcfg page
 */
static void __init vdso_setup_syscall_map(void)
{
        unsigned int i;
        extern unsigned long *sys_call_table;
        extern unsigned long sys_ni_syscall;


        for (i = 0; i < __NR_syscalls; i++) {
#ifdef CONFIG_PPC64
                if (sys_call_table[i*2] != sys_ni_syscall)
                        vdso_data->syscall_map_64[i >> 5] |=
                                0x80000000UL >> (i & 0x1f);
                if (sys_call_table[i*2+1] != sys_ni_syscall)
                        vdso_data->syscall_map_32[i >> 5] |=
                                0x80000000UL >> (i & 0x1f);
#else /* CONFIG_PPC64 */
                if (sys_call_table[i] != sys_ni_syscall)
                        vdso_data->syscall_map_32[i >> 5] |=
                                0x80000000UL >> (i & 0x1f);
#endif /* CONFIG_PPC64 */
        }
}


void __init vdso_init(void)
{
        int i;

#ifdef CONFIG_PPC64
        /*
         * Fill up the "systemcfg" stuff for backward compatiblity
         */
        strcpy(vdso_data->eye_catcher, "SYSTEMCFG:PPC64");
        vdso_data->version.major = SYSTEMCFG_MAJOR;
        vdso_data->version.minor = SYSTEMCFG_MINOR;
        vdso_data->processor = mfspr(SPRN_PVR);
        /*
         * Fake the old platform number for pSeries and iSeries and add
         * in LPAR bit if necessary
         */
        vdso_data->platform = machine_is(iseries) ? 0x200 : 0x100;
        if (firmware_has_feature(FW_FEATURE_LPAR))
                vdso_data->platform |= 1;
        vdso_data->physicalMemorySize = lmb_phys_mem_size();
        vdso_data->dcache_size = ppc64_caches.dsize;
        vdso_data->dcache_line_size = ppc64_caches.dline_size;
        vdso_data->icache_size = ppc64_caches.isize;
        vdso_data->icache_line_size = ppc64_caches.iline_size;

        /*
         * Calculate the size of the 64 bits vDSO
         */
        vdso64_pages = (&vdso64_end - &vdso64_start) >> PAGE_SHIFT;
        DBG("vdso64_kbase: %p, 0x%x pages\n", vdso64_kbase, vdso64_pages);
#endif /* CONFIG_PPC64 */


        /*
         * Calculate the size of the 32 bits vDSO
         */
        vdso32_pages = (&vdso32_end - &vdso32_start) >> PAGE_SHIFT;
        DBG("vdso32_kbase: %p, 0x%x pages\n", vdso32_kbase, vdso32_pages);


        /*
         * Setup the syscall map in the vDOS
         */
        vdso_setup_syscall_map();
        /*
         * Initialize the vDSO images in memory, that is do necessary
         * fixups of vDSO symbols, locate trampolines, etc...
         */
        if (vdso_setup()) {
                printk(KERN_ERR "vDSO setup failure, not enabled !\n");
                vdso32_pages = 0;
#ifdef CONFIG_PPC64
                vdso64_pages = 0;
#endif
                return;
        }

        /* Make sure pages are in the correct state */
        for (i = 0; i < vdso32_pages; i++) {
                struct page *pg = virt_to_page(vdso32_kbase + i*PAGE_SIZE);
                ClearPageReserved(pg);
                get_page(pg);

        }
#ifdef CONFIG_PPC64
        for (i = 0; i < vdso64_pages; i++) {
                struct page *pg = virt_to_page(vdso64_kbase + i*PAGE_SIZE);
                ClearPageReserved(pg);
                get_page(pg);
        }
#endif /* CONFIG_PPC64 */

        get_page(virt_to_page(vdso_data));
}

int in_gate_area_no_task(unsigned long addr)
{
        return 0;
}

int in_gate_area(struct task_struct *task, unsigned long addr)
{
        return 0;
}

struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
{
        return NULL;
}