mm: replace pte_write with pte_access_permitted in fault + gup paths

The 'access_permitted' helper is used in the gup-fast path and goes
beyond the simple _PAGE_RW check to also:

 - validate that the mapping is writable from a protection keys
   standpoint

 - validate that the pte has _PAGE_USER set since all fault paths where
   pte_write is must be referencing user-memory.

Link: http://lkml.kernel.org/r/151043111604.2842.8051684481794973100.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/mm/memory.c b/mm/memory.c
index 416e451a707e..4f07acd1695f 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3948,7 +3948,7 @@ static int handle_pte_fault(struct vm_fault *vmf)
         if (unlikely(!pte_same(*vmf->pte, entry)))
                 goto unlock;
         if (vmf->flags & FAULT_FLAG_WRITE) {
-                if (!pte_write(entry))
+                if (!pte_access_permitted(entry, WRITE))
                         return do_wp_page(vmf);
                 entry = pte_mkdirty(entry);
         }
@@ -4336,7 +4336,7 @@ int follow_phys(struct vm_area_struct *vma,
                 goto out;
         pte = *ptep;
 
-        if ((flags & FOLL_WRITE) && !pte_write(pte))
+        if (!pte_access_permitted(pte, flags & FOLL_WRITE))
                 goto unlock;
 
         *prot = pgprot_val(pte_pgprot(pte));