mm: replace pmd_write with pmd_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
   pmd_write is must be referencing user-memory.

Link: http://lkml.kernel.org/r/151043111049.2842.15241454964150083466.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: "Jérôme Glisse" <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Dan Williams 2017-11-29 16:10:18 -08:00 • committed by Linus Torvalds
commit c7da82b894
5 changed files with 8 additions and 7 deletions

View file

@ -627,7 +627,8 @@ static void dax_mapping_entry_mkclean(struct address_space *mapping,
if (pfn != pmd_pfn(*pmdp))
goto unlock_pmd;
if (!pmd_dirty(*pmdp) && !pmd_write(*pmdp))
if (!pmd_dirty(*pmdp)
&& !pmd_access_permitted(*pmdp, WRITE))
goto unlock_pmd;
flush_cache_page(vma, address, pfn);