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    SubjectRe: Removing MAX_ARG_PAGES (request for comments/assistance)
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    On Tue, 2006-10-10 at 17:05 -0700, Ollie Wild wrote:

    > + vma->vm_flags &= ~VM_EXEC;
    > + // FIXME: Are the next two lines sufficient, or do I need to
    > + // do some additional magic?
    > + vma->vm_flags |= mm->def_flags;
    > + vma->vm_page_prot = protection_map[vma->vm_flags & 0x7];

    Yeah, you'll need to change the PTEs for those pages you created by
    calling get_user_page() by calling an mprotect like function; perhaps
    something like:

    struct vm_area_struct *prev;
    unsigned long vm_flags = vma->vm_flags;

    s/vma->vm_flags/vm_flags/g

    err = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end, vm_flags);
    BUG_ON(prev != vma);

    mprotect_fixup will then set the new protection on all PTEs and update
    vma->vm_flags and vma->vm_page_prot.

    > + /* Move stack pages down in memory. */
    > + if (stack_shift) {
    > + // FIXME: Verify the shift is OK.
    > +

    What exactly are you wondering about? the call to move_vma looks sane to
    me

    > + /* This should be safe even with overlap because we
    > + * are shifting down. */
    > + ret = move_vma(vma, vma->vm_start,
    > + vma->vm_end - vma->vm_start,
    > + vma->vm_end - vma->vm_start,
    > + vma->vm_start - stack_shift);
    > + if (ret & ~PAGE_MASK) {
    > + up_write(&mm->mmap_sem);
    > + return ret;
    > + }
    > }


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