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Commit e121e418 authored by venkatesh.pallipadi@intel.com's avatar venkatesh.pallipadi@intel.com Committed by H. Peter Anvin
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x86: PAT: add follow_pfnmp_pte routine to help tracking pfnmap pages - v3 



Impact: New currently unused interface.

Add a generic interface to follow pfn in a pfnmap vma range. This is used by
one of the subsequent x86 PAT related patch to keep track of memory types
for vma regions across vma copy and free.

Signed-off-by: default avatarVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: default avatarSuresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
parent 3c8bb73a

include/linux/mm.h

+3 −0
Original line number Diff line number Diff line
@@ -1223,6 +1223,9 @@ struct page *follow_page(struct vm_area_struct *, unsigned long address, 
#define FOLL_GET	0x04	/* do get_page on page */

#define FOLL_ANON	0x08	/* give ZERO_PAGE if no pgtable */



int follow_pfnmap_pte(struct vm_area_struct *vma,

				unsigned long address, pte_t *ret_ptep);



typedef int (*pte_fn_t)(pte_t *pte, pgtable_t token, unsigned long addr,

			void *data);

extern int apply_to_page_range(struct mm_struct *mm, unsigned long address,

mm/memory.c

+43 −0
Original line number Diff line number Diff line
@@ -1111,6 +1111,49 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address, 
	return page;

}



int follow_pfnmap_pte(struct vm_area_struct *vma, unsigned long address,

			pte_t *ret_ptep)

{

	pgd_t *pgd;

	pud_t *pud;

	pmd_t *pmd;

	pte_t *ptep, pte;

	spinlock_t *ptl;

	struct page *page;

	struct mm_struct *mm = vma->vm_mm;



	if (!is_pfn_mapping(vma))

		goto err;



	page = NULL;

	pgd = pgd_offset(mm, address);

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

		goto err;



	pud = pud_offset(pgd, address);

	if (pud_none(*pud) || unlikely(pud_bad(*pud)))

		goto err;



	pmd = pmd_offset(pud, address);

	if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))

		goto err;



	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);



	pte = *ptep;

	if (!pte_present(pte))

		goto err_unlock;



	*ret_ptep = pte;

	pte_unmap_unlock(ptep, ptl);

	return 0;



err_unlock:

	pte_unmap_unlock(ptep, ptl);

err:

	return -EINVAL;

}



/* Can we do the FOLL_ANON optimization? */

static inline int use_zero_page(struct vm_area_struct *vma)

{