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>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 2be8d9b5e46f..a25024ff9c11 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -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,