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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/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>

#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

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 __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
      },
      {
            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/* && 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 */

/*
 * 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 page **vdso_pagelist;
      unsigned long vdso_pages;
      unsigned long vdso_base;
      int rc;

      if (!vdso_ready)
            return 0;

#ifdef CONFIG_PPC64
      if (test_thread_flag(TIF_32BIT)) {
            vdso_pagelist = vdso32_pagelist;
            vdso_pages = vdso32_pages;
            vdso_base = VDSO32_MBASE;
      } else {
            vdso_pagelist = vdso64_pagelist;
            vdso_pages = vdso64_pages;
            vdso_base = VDSO64_MBASE;
      }
#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.
       */
      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;
      }

      /*
       * 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
       *
       * Make sure the vDSO gets into every core dump.
       * Dumping its contents makes post-mortem fully interpretable later
       * without matching up the same kernel and hardware config to see
       * what PC values meant.
       */
      rc = install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
                             VM_READ|VM_EXEC|
                             VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
                             VM_ALWAYSDUMP,
                             vdso_pagelist);
      if (rc)
            goto fail_mmapsem;

      /* Put vDSO base into mm struct */
      current->mm->context.vdso_base = vdso_base;

      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 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_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, "__fw_ftr_fixup", &size64);
      if (start64)
            do_feature_fixups(powerpc_firmware_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);

#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 */

      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 */
      }
}


static int __init vdso_init(void)
{
      int i;

#ifdef CONFIG_PPC64
      /*
       * Fill up the "systemcfg" stuff for backward compatiblity
       */
      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 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;

      /* 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;
}
#ifdef CONFIG_PPC_MERGE
arch_initcall(vdso_init);
#endif

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;
}


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