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Commit f2b495ca authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Linus Torvalds
Browse files

mm: extract in_gate_area() case from __get_user_pages() 



The case is special and disturb from reading main __get_user_pages()
code path. Let's move it to separate function.

Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4bbd4c77

mm/gup.c

+48 −42
Original line number Diff line number Diff line
@@ -213,6 +213,50 @@ static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long add 
	       stack_guard_page_end(vma, addr+PAGE_SIZE);

}



static int get_gate_page(struct mm_struct *mm, unsigned long address,

		unsigned int gup_flags, struct vm_area_struct **vma,

		struct page **page)

{

	pgd_t *pgd;

	pud_t *pud;

	pmd_t *pmd;

	pte_t *pte;

	int ret = -EFAULT;



	/* user gate pages are read-only */

	if (gup_flags & FOLL_WRITE)

		return -EFAULT;

	if (address > TASK_SIZE)

		pgd = pgd_offset_k(address);

	else

		pgd = pgd_offset_gate(mm, address);

	BUG_ON(pgd_none(*pgd));

	pud = pud_offset(pgd, address);

	BUG_ON(pud_none(*pud));

	pmd = pmd_offset(pud, address);

	if (pmd_none(*pmd))

		return -EFAULT;

	VM_BUG_ON(pmd_trans_huge(*pmd));

	pte = pte_offset_map(pmd, address);

	if (pte_none(*pte))

		goto unmap;

	*vma = get_gate_vma(mm);

	if (!page)

		goto out;

	*page = vm_normal_page(*vma, address, *pte);

	if (!*page) {

		if ((gup_flags & FOLL_DUMP) || !is_zero_pfn(pte_pfn(*pte)))

			goto unmap;

		*page = pte_page(*pte);

	}

	get_page(*page);

out:

	ret = 0;

unmap:

	pte_unmap(pte);

	return ret;

}



/**

 * __get_user_pages() - pin user pages in memory

 * @tsk:	task_struct of target task
@@ -291,49 +335,11 @@ long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 


		vma = find_extend_vma(mm, start);

		if (!vma && in_gate_area(mm, start)) {

			unsigned long pg = start & PAGE_MASK;

			pgd_t *pgd;

			pud_t *pud;

			pmd_t *pmd;

			pte_t *pte;



			/* user gate pages are read-only */

			if (gup_flags & FOLL_WRITE)

				goto efault;

			if (pg > TASK_SIZE)

				pgd = pgd_offset_k(pg);

			else

				pgd = pgd_offset_gate(mm, pg);

			BUG_ON(pgd_none(*pgd));

			pud = pud_offset(pgd, pg);

			BUG_ON(pud_none(*pud));

			pmd = pmd_offset(pud, pg);

			if (pmd_none(*pmd))

				goto efault;

			VM_BUG_ON(pmd_trans_huge(*pmd));

			pte = pte_offset_map(pmd, pg);

			if (pte_none(*pte)) {

				pte_unmap(pte);

				goto efault;

			}

			vma = get_gate_vma(mm);

			if (pages) {

				struct page *page;



				page = vm_normal_page(vma, start, *pte);

				if (!page) {

					if (!(gup_flags & FOLL_DUMP) &&

					     is_zero_pfn(pte_pfn(*pte)))

						page = pte_page(*pte);

					else {

						pte_unmap(pte);

			int ret;

			ret = get_gate_page(mm, start & PAGE_MASK, gup_flags,

					&vma, pages ? &pages[i] : NULL);

			if (ret)

				goto efault;

					}

				}

				pages[i] = page;

				get_page(page);

			}

			pte_unmap(pte);

			page_mask = 0;

			goto next_page;

		}