From f2b495ca82e188fd2818479a551f126edf023756 Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" Date: Wed, 4 Jun 2014 16:08:11 -0700 Subject: [PATCH] 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: Kirill A. Shutemov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/gup.c | 90 ++++++++++++++++++++++++++++++-------------------------- 1 file changed, 48 insertions(+), 42 deletions(-) diff --git a/mm/gup.c b/mm/gup.c index ea88b65f264d..0bf127b332e7 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -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)) + int ret; + ret = get_gate_page(mm, start & PAGE_MASK, gup_flags, + &vma, pages ? &pages[i] : NULL); + if (ret) 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); - goto efault; - } - } - pages[i] = page; - get_page(page); - } - pte_unmap(pte); page_mask = 0; goto next_page; } -- 2.20.1