vdso.c

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/*
 *    Copyright (C) 2004 Benjamin Herrenschmidt, IBM Corp.
 *           <[email protected]>
 *
 *  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/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/smp.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 <linux/memblock.h>

#include <asm/pgtable.h>
#include <asm/processor.h>
#include <asm/mmu.h>
#include <asm/mmu_context.h>
#include <asm/prom.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>

#include "setup.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

/* The alignment of the vDSO */
#define VDSO_ALIGNMENT  (1 << 16)

extern char vdso32_start, vdso32_end;
static void *vdso32_kbase = &vdso32_start;
static unsigned int vdso32_pages;
static struct page **vdso32_pagelist;
unsigned long vdso32_sigtramp;
unsigned long vdso32_rt_sigtramp;

#ifdef CONFIG_PPC64
extern char vdso64_start, vdso64_end;
static void *vdso64_kbase = &vdso64_start;
static unsigned int vdso64_pages;
static struct page **vdso64_pagelist;
unsigned long vdso64_rt_sigtramp;
#endif /* CONFIG_PPC64 */

static int vdso_ready;

/*
 * 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 __page_aligned_data;
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
    },
    {
        CPU_FTR_USE_TB, 0,
        "__kernel_clock_gettime", NULL
    },
    {
        CPU_FTR_USE_TB, 0,
        "__kernel_clock_getres", NULL
    },
    {
        CPU_FTR_USE_TB, 0,
        "__kernel_get_tbfreq", 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 && !IS_ERR(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 || is_32bit_task()) {
        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 || !is_32bit_task()) {
        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 */

/*
 * 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 uses_interp)
{
    struct mm_struct *mm = current->mm;
    struct page **vdso_pagelist;
    unsigned long vdso_pages;
    unsigned long vdso_base;
    int rc;

    if (!vdso_ready)
        return 0;

#ifdef CONFIG_PPC64
    if (is_32bit_task()) {
        vdso_pagelist = vdso32_pagelist;
        vdso_pages = vdso32_pages;
        vdso_base = VDSO32_MBASE;
    } else {
        vdso_pagelist = vdso64_pagelist;
        vdso_pages = vdso64_pages;
        /*
         * On 64bit we don't have a preferred map address. This
         * allows get_unmapped_area to find an area near other mmaps
         * and most likely share a SLB entry.
         */
        vdso_base = 0;
    }
#else
    vdso_pagelist = vdso32_pagelist;
    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.
     * Add enough to the size so that the result can be aligned.
     */
    down_write(&mm->mmap_sem);
    vdso_base = get_unmapped_area(NULL, vdso_base,
                      (vdso_pages << PAGE_SHIFT) +
                      ((VDSO_ALIGNMENT - 1) & PAGE_MASK),
                      0, 0);
    if (IS_ERR_VALUE(vdso_base)) {
        rc = vdso_base;
        goto fail_mmapsem;
    }

    /* Add required alignment. */
    vdso_base = ALIGN(vdso_base, VDSO_ALIGNMENT);

    /*
     * Put vDSO base into mm struct. We need to do this before calling
     * install_special_mapping or the perf counter mmap tracking code
     * will fail to recognise it as a vDSO (since arch_vma_name fails).
     */
    current->mm->context.vdso_base = vdso_base;

    /*
     * 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.
     */
    rc = install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
                     VM_READ|VM_EXEC|
                     VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
                     vdso_pagelist);
    if (rc) {
        current->mm->context.vdso_base = 0;
        goto fail_mmapsem;
    }

    up_write(&mm->mmap_sem);
    return 0;

 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 __init 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 __init 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_features(struct lib32_elfinfo *v32,
                      struct lib64_elfinfo *v64)
{
    void *start32;
    unsigned long size32;

#ifdef CONFIG_PPC64
    void *start64;
    unsigned long size64;

    start64 = find_section64(v64->hdr, "__ftr_fixup", &size64);
    if (start64)
        do_feature_fixups(cur_cpu_spec->cpu_features,
                  start64, start64 + size64);

    start64 = find_section64(v64->hdr, "__mmu_ftr_fixup", &size64);
    if (start64)
        do_feature_fixups(cur_cpu_spec->mmu_features,
                  start64, start64 + size64);

    start64 = find_section64(v64->hdr, "__fw_ftr_fixup", &size64);
    if (start64)
        do_feature_fixups(powerpc_firmware_features,
                  start64, start64 + size64);

    start64 = find_section64(v64->hdr, "__lwsync_fixup", &size64);
    if (start64)
        do_lwsync_fixups(cur_cpu_spec->cpu_features,
                 start64, start64 + size64);
#endif /* CONFIG_PPC64 */

    start32 = find_section32(v32->hdr, "__ftr_fixup", &size32);
    if (start32)
        do_feature_fixups(cur_cpu_spec->cpu_features,
                  start32, start32 + size32);

    start32 = find_section32(v32->hdr, "__mmu_ftr_fixup", &size32);
    if (start32)
        do_feature_fixups(cur_cpu_spec->mmu_features,
                  start32, start32 + size32);

#ifdef CONFIG_PPC64
    start32 = find_section32(v32->hdr, "__fw_ftr_fixup", &size32);
    if (start32)
        do_feature_fixups(powerpc_firmware_features,
                  start32, start32 + size32);
#endif /* CONFIG_PPC64 */

    start32 = find_section32(v32->hdr, "__lwsync_fixup", &size32);
    if (start32)
        do_lwsync_fixups(cur_cpu_spec->cpu_features,
                 start32, start32 + size32);

    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_features(&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 */
    }
}

#ifdef CONFIG_PPC64
int __cpuinit vdso_getcpu_init(void)
{
    unsigned long cpu, node, val;

    /*
     * SPRG3 contains the CPU in the bottom 16 bits and the NUMA node in
     * the next 16 bits. The VDSO uses this to implement getcpu().
     */
    cpu = get_cpu();
    WARN_ON_ONCE(cpu > 0xffff);

    node = cpu_to_node(cpu);
    WARN_ON_ONCE(node > 0xffff);

    val = (cpu & 0xfff) | ((node & 0xffff) << 16);
    mtspr(SPRN_SPRG3, val);
    get_paca()->sprg3 = val;

    put_cpu();

    return 0;
}
/* We need to call this before SMP init */
early_initcall(vdso_getcpu_init);
#endif

static int __init vdso_init(void)
{
    int i;

#ifdef CONFIG_PPC64
    /*
     * Fill up the "systemcfg" stuff for backward compatibility
     */
    strcpy((char *)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 add
     * in LPAR bit if necessary
     */
    vdso_data->platform = 0x100;
    if (firmware_has_feature(FW_FEATURE_LPAR))
        vdso_data->platform |= 1;
    vdso_data->physicalMemorySize = memblock_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;

    /* XXXOJN: Blocks should be added to ppc64_caches and used instead */
    vdso_data->dcache_block_size = ppc64_caches.dline_size;
    vdso_data->icache_block_size = ppc64_caches.iline_size;
    vdso_data->dcache_log_block_size = ppc64_caches.log_dline_size;
    vdso_data->icache_log_block_size = ppc64_caches.log_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);
#else
    vdso_data->dcache_block_size = L1_CACHE_BYTES;
    vdso_data->dcache_log_block_size = L1_CACHE_SHIFT;
    vdso_data->icache_block_size = L1_CACHE_BYTES;
    vdso_data->icache_log_block_size = L1_CACHE_SHIFT;
#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 0;
    }

    /* Make sure pages are in the correct state */
    vdso32_pagelist = kzalloc(sizeof(struct page *) * (vdso32_pages + 2),
                  GFP_KERNEL);
    BUG_ON(vdso32_pagelist == NULL);
    for (i = 0; i < vdso32_pages; i++) {
        struct page *pg = virt_to_page(vdso32_kbase + i*PAGE_SIZE);
        ClearPageReserved(pg);
        get_page(pg);
        vdso32_pagelist[i] = pg;
    }
    vdso32_pagelist[i++] = virt_to_page(vdso_data);
    vdso32_pagelist[i] = NULL;

#ifdef CONFIG_PPC64
    vdso64_pagelist = kzalloc(sizeof(struct page *) * (vdso64_pages + 2),
                  GFP_KERNEL);
    BUG_ON(vdso64_pagelist == NULL);
    for (i = 0; i < vdso64_pages; i++) {
        struct page *pg = virt_to_page(vdso64_kbase + i*PAGE_SIZE);
        ClearPageReserved(pg);
        get_page(pg);
        vdso64_pagelist[i] = pg;
    }
    vdso64_pagelist[i++] = virt_to_page(vdso_data);
    vdso64_pagelist[i] = NULL;
#endif /* CONFIG_PPC64 */

    get_page(virt_to_page(vdso_data));

    smp_wmb();
    vdso_ready = 1;

    return 0;
}
arch_initcall(vdso_init);

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

int in_gate_area(struct mm_struct *mm, unsigned long addr)
{
    return 0;
}

struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
{
    return NULL;
}