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 <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/gup.c b/mm/gup.c
index ea88b65..0bf127b 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -213,6 +213,50 @@
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 @@
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)
+ int ret;
+ ret = get_gate_page(mm, start & PAGE_MASK, gup_flags,
+ &vma, pages ? &pages[i] : NULL);
+ if (ret)
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);
- goto efault;
- }
- }
- pages[i] = page;
- get_page(page);
- }
- pte_unmap(pte);
page_mask = 0;
goto next_page;
}