Commit 080dbb61 authored by Aneesh Kumar K.V's avatar Aneesh Kumar K.V Committed by Linus Torvalds
Browse files

mm/follow_page_mask: split follow_page_mask to smaller functions. 

Makes code reading easy.  No functional changes in this patch.  In a
followup patch, we will be updating the follow_page_mask to handle
hugetlb hugepd format so that archs like ppc64 can switch to the generic
version.  This split helps in doing that nicely.

Link: http://lkml.kernel.org/r/1494926612-23928-3-git-send-email-aneesh.kumar@linux.vnet.ibm.com


Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Reviewed-by: default avatarNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Mike Kravetz <kravetz@us.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 383321ab

mm/gup.c

+91 −57
Original line number Diff line number Diff line
@@ -208,68 +208,16 @@ no_page: 
	return no_page_table(vma, flags);

}



/**

 * follow_page_mask - look up a page descriptor from a user-virtual address

 * @vma: vm_area_struct mapping @address

 * @address: virtual address to look up

 * @flags: flags modifying lookup behaviour

 * @page_mask: on output, *page_mask is set according to the size of the page

 *

 * @flags can have FOLL_ flags set, defined in <linux/mm.h>

 *

 * Returns the mapped (struct page *), %NULL if no mapping exists, or

 * an error pointer if there is a mapping to something not represented

 * by a page descriptor (see also vm_normal_page()).

 */

struct page *follow_page_mask(struct vm_area_struct *vma,

			      unsigned long address, unsigned int flags,

			      unsigned int *page_mask)

static struct page *follow_pmd_mask(struct vm_area_struct *vma,

				    unsigned long address, pud_t *pudp,

				    unsigned int flags, unsigned int *page_mask)

{

	pgd_t *pgd;

	p4d_t *p4d;

	pud_t *pud;

	pmd_t *pmd;

	spinlock_t *ptl;

	struct page *page;

	struct mm_struct *mm = vma->vm_mm;



	*page_mask = 0;



	page = follow_huge_addr(mm, address, flags & FOLL_WRITE);

	if (!IS_ERR(page)) {

		BUG_ON(flags & FOLL_GET);

		return page;

	}



	pgd = pgd_offset(mm, address);

	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))

		return no_page_table(vma, flags);

	p4d = p4d_offset(pgd, address);

	if (p4d_none(*p4d))

		return no_page_table(vma, flags);

	BUILD_BUG_ON(p4d_huge(*p4d));

	if (unlikely(p4d_bad(*p4d)))

		return no_page_table(vma, flags);

	pud = pud_offset(p4d, address);

	if (pud_none(*pud))

		return no_page_table(vma, flags);

	if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) {

		page = follow_huge_pud(mm, address, pud, flags);

		if (page)

			return page;

		return no_page_table(vma, flags);

	}

	if (pud_devmap(*pud)) {

		ptl = pud_lock(mm, pud);

		page = follow_devmap_pud(vma, address, pud, flags);

		spin_unlock(ptl);

		if (page)

			return page;

	}

	if (unlikely(pud_bad(*pud)))

		return no_page_table(vma, flags);



	pmd = pmd_offset(pud, address);

	pmd = pmd_offset(pudp, address);

	if (pmd_none(*pmd))

		return no_page_table(vma, flags);

	if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) {
@@ -319,13 +267,99 @@ struct page *follow_page_mask(struct vm_area_struct *vma, 
		return ret ? ERR_PTR(ret) :

			follow_page_pte(vma, address, pmd, flags);

	}



	page = follow_trans_huge_pmd(vma, address, pmd, flags);

	spin_unlock(ptl);

	*page_mask = HPAGE_PMD_NR - 1;

	return page;

}





static struct page *follow_pud_mask(struct vm_area_struct *vma,

				    unsigned long address, p4d_t *p4dp,

				    unsigned int flags, unsigned int *page_mask)

{

	pud_t *pud;

	spinlock_t *ptl;

	struct page *page;

	struct mm_struct *mm = vma->vm_mm;



	pud = pud_offset(p4dp, address);

	if (pud_none(*pud))

		return no_page_table(vma, flags);

	if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) {

		page = follow_huge_pud(mm, address, pud, flags);

		if (page)

			return page;

		return no_page_table(vma, flags);

	}

	if (pud_devmap(*pud)) {

		ptl = pud_lock(mm, pud);

		page = follow_devmap_pud(vma, address, pud, flags);

		spin_unlock(ptl);

		if (page)

			return page;

	}

	if (unlikely(pud_bad(*pud)))

		return no_page_table(vma, flags);



	return follow_pmd_mask(vma, address, pud, flags, page_mask);

}





static struct page *follow_p4d_mask(struct vm_area_struct *vma,

				    unsigned long address, pgd_t *pgdp,

				    unsigned int flags, unsigned int *page_mask)

{

	p4d_t *p4d;



	p4d = p4d_offset(pgdp, address);

	if (p4d_none(*p4d))

		return no_page_table(vma, flags);

	BUILD_BUG_ON(p4d_huge(*p4d));

	if (unlikely(p4d_bad(*p4d)))

		return no_page_table(vma, flags);



	return follow_pud_mask(vma, address, p4d, flags, page_mask);

}



/**

 * follow_page_mask - look up a page descriptor from a user-virtual address

 * @vma: vm_area_struct mapping @address

 * @address: virtual address to look up

 * @flags: flags modifying lookup behaviour

 * @page_mask: on output, *page_mask is set according to the size of the page

 *

 * @flags can have FOLL_ flags set, defined in <linux/mm.h>

 *

 * Returns the mapped (struct page *), %NULL if no mapping exists, or

 * an error pointer if there is a mapping to something not represented

 * by a page descriptor (see also vm_normal_page()).

 */

struct page *follow_page_mask(struct vm_area_struct *vma,

			      unsigned long address, unsigned int flags,

			      unsigned int *page_mask)

{

	pgd_t *pgd;

	struct page *page;

	struct mm_struct *mm = vma->vm_mm;



	*page_mask = 0;



	/* make this handle hugepd */

	page = follow_huge_addr(mm, address, flags & FOLL_WRITE);

	if (!IS_ERR(page)) {

		BUG_ON(flags & FOLL_GET);

		return page;

	}



	pgd = pgd_offset(mm, address);



	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))

		return no_page_table(vma, flags);



	return follow_p4d_mask(vma, address, pgd, flags, page_mask);

}



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

		unsigned int gup_flags, struct vm_area_struct **vma,

		struct page **page)

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