forked from Minki/linux
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: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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@ -1223,6 +1223,9 @@ struct page *follow_page(struct vm_area_struct *, unsigned long address,
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#define FOLL_GET 0x04 /* do get_page on page */
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#define FOLL_ANON 0x08 /* give ZERO_PAGE if no pgtable */
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int follow_pfnmap_pte(struct vm_area_struct *vma,
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unsigned long address, pte_t *ret_ptep);
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typedef int (*pte_fn_t)(pte_t *pte, pgtable_t token, unsigned long addr,
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void *data);
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extern int apply_to_page_range(struct mm_struct *mm, unsigned long address,
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43
mm/memory.c
43
mm/memory.c
@ -1111,6 +1111,49 @@ no_page_table:
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return page;
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}
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int follow_pfnmap_pte(struct vm_area_struct *vma, unsigned long address,
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pte_t *ret_ptep)
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{
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pgd_t *pgd;
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pud_t *pud;
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pmd_t *pmd;
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pte_t *ptep, pte;
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spinlock_t *ptl;
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struct page *page;
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struct mm_struct *mm = vma->vm_mm;
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if (!is_pfn_mapping(vma))
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goto err;
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page = NULL;
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pgd = pgd_offset(mm, address);
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if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
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goto err;
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pud = pud_offset(pgd, address);
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if (pud_none(*pud) || unlikely(pud_bad(*pud)))
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goto err;
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pmd = pmd_offset(pud, address);
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if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
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goto err;
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ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
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pte = *ptep;
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if (!pte_present(pte))
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goto err_unlock;
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*ret_ptep = pte;
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pte_unmap_unlock(ptep, ptl);
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return 0;
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err_unlock:
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pte_unmap_unlock(ptep, ptl);
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err:
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return -EINVAL;
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}
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/* Can we do the FOLL_ANON optimization? */
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static inline int use_zero_page(struct vm_area_struct *vma)
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{
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