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    Subject[PATCH 9/11] i386 vDSO: use install_special_mapping
    Date

    This patch uses install_special_mapping for the i386 vDSO setup,
    consolidating duplicated code.

    Signed-off-by: Roland McGrath <roland@redhat.com>
    ---
    arch/i386/kernel/sysenter.c | 53 +++++++++----------------------------------
    1 files changed, 11 insertions(+), 42 deletions(-)

    diff --git a/arch/i386/kernel/sysenter.c b/arch/i386/kernel/sysenter.c
    index 5da7442..bc882a2 100644
    --- a/arch/i386/kernel/sysenter.c
    +++ b/arch/i386/kernel/sysenter.c
    @@ -70,11 +70,12 @@ void enable_sep_cpu(void)
    */
    extern const char vsyscall_int80_start, vsyscall_int80_end;
    extern const char vsyscall_sysenter_start, vsyscall_sysenter_end;
    -static void *syscall_page;
    +static struct page *syscall_pages[1];

    int __init sysenter_setup(void)
    {
    - syscall_page = (void *)get_zeroed_page(GFP_ATOMIC);
    + void *syscall_page = (void *)get_zeroed_page(GFP_ATOMIC);
    + syscall_pages[0] = virt_to_page(syscall_page);

    #ifdef CONFIG_COMPAT_VDSO
    __set_fixmap(FIX_VDSO, __pa(syscall_page), PAGE_READONLY);
    @@ -96,31 +97,12 @@ int __init sysenter_setup(void)
    }

    #ifndef CONFIG_COMPAT_VDSO
    -static struct page *syscall_nopage(struct vm_area_struct *vma,
    - unsigned long adr, int *type)
    -{
    - struct page *p = virt_to_page(adr - vma->vm_start + syscall_page);
    - get_page(p);
    - return p;
    -}
    -
    -/* Prevent VMA merging */
    -static void syscall_vma_close(struct vm_area_struct *vma)
    -{
    -}
    -
    -static struct vm_operations_struct syscall_vm_ops = {
    - .close = syscall_vma_close,
    - .nopage = syscall_nopage,
    -};
    -
    /* Defined in vsyscall-sysenter.S */
    extern void SYSENTER_RETURN;

    /* Setup a VMA at program startup for the vsyscall page */
    int arch_setup_additional_pages(struct linux_binprm *bprm, int exstack)
    {
    - struct vm_area_struct *vma;
    struct mm_struct *mm = current->mm;
    unsigned long addr;
    int ret;
    @@ -132,38 +114,25 @@ int arch_setup_additional_pages(struct l
    goto up_fail;
    }

    - vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
    - if (!vma) {
    - ret = -ENOMEM;
    - goto up_fail;
    - }
    -
    - vma->vm_start = addr;
    - vma->vm_end = addr + PAGE_SIZE;
    - /* MAYWRITE to allow gdb to COW and set breakpoints */
    - vma->vm_flags = VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC|VM_MAYWRITE;
    /*
    + * MAYWRITE to allow gdb to COW and set breakpoints
    + *
    * 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.
    */
    - vma->vm_flags |= VM_ALWAYSDUMP;
    - vma->vm_flags |= mm->def_flags;
    - vma->vm_page_prot = protection_map[vma->vm_flags & 7];
    - vma->vm_ops = &syscall_vm_ops;
    - vma->vm_mm = mm;
    -
    - ret = insert_vm_struct(mm, vma);
    - if (unlikely(ret)) {
    - kmem_cache_free(vm_area_cachep, vma);
    + ret = install_special_mapping(mm, addr, PAGE_SIZE,
    + VM_READ|VM_EXEC|
    + VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
    + VM_ALWAYSDUMP,
    + syscall_pages);
    + if (ret)
    goto up_fail;
    - }

    current->mm->context.vdso = (void *)addr;
    current_thread_info()->sysenter_return =
    (void *)VDSO_SYM(&SYSENTER_RETURN);
    - mm->total_vm++;
    up_fail:
    up_write(&mm->mmap_sem);
    return ret;
    -
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