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mm: extract in_gate_area() case from __get_user_pages()

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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>
This commit is contained in:
Kirill A. Shutemov 2014-06-04 16:08:11 -07:00 committed by Linus Torvalds
parent 4bbd4c776a
commit f2b495ca82
1 changed files with 48 additions and 42 deletions
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90
mm/gup.c
View file

@ -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)
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;
}