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 <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>

diff --git a/arch/sparc/mm/gup.c b/arch/sparc/mm/gup.c
index 5ae2d0a..33c0f8b 100644 (file)
--- a/arch/sparc/mm/gup.c
+++ b/arch/sparc/mm/gup.c
@@ -75,7 +75,7 @@ static int gup_huge_pmd(pmd_t *pmdp, pmd_t pmd, unsigned long addr,
        if (!(pmd_val(pmd) & _PAGE_VALID))
                return 0;
 
-       if (write && !pmd_write(pmd))
+       if (!pmd_access_permitted(pmd, write))
                return 0;
 
        refs = 0;

diff --git a/fs/dax.c b/fs/dax.c
index 9598159..78b72c4 100644 (file)
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -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);

diff --git a/mm/hmm.c b/mm/hmm.c
index ea19742..93718a3 100644 (file)
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -391,11 +391,11 @@ again:
                if (pmd_protnone(pmd))
                        return hmm_vma_walk_clear(start, end, walk);
 
-               if (write_fault && !pmd_write(pmd))
+               if (!pmd_access_permitted(pmd, write_fault))
                        return hmm_vma_walk_clear(start, end, walk);
 
                pfn = pmd_pfn(pmd) + pte_index(addr);
-               flag |= pmd_write(pmd) ? HMM_PFN_WRITE : 0;
+               flag |= pmd_access_permitted(pmd, WRITE) ? HMM_PFN_WRITE : 0;
                for (; addr < end; addr += PAGE_SIZE, i++, pfn++)
                        pfns[i] = hmm_pfn_t_from_pfn(pfn) | flag;
                return 0;

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 4fe2491..05b729f 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -877,7 +877,7 @@ struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
         */
        WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set");
 
-       if (flags & FOLL_WRITE && !pmd_write(*pmd))
+       if (!pmd_access_permitted(*pmd, flags & FOLL_WRITE))
                return NULL;
 
        if (pmd_present(*pmd) && pmd_devmap(*pmd))
@@ -1393,7 +1393,7 @@ out_unlock:
  */
 static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags)
 {
-       return pmd_write(pmd) ||
+       return pmd_access_permitted(pmd, WRITE) ||
               ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd));
 }
 

diff --git a/mm/memory.c b/mm/memory.c
index 25d283d..416e451 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4046,7 +4046,7 @@ static int __handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
                        if (pmd_protnone(orig_pmd) && vma_is_accessible(vma))
                                return do_huge_pmd_numa_page(&vmf, orig_pmd);
 
-                       if (dirty && !pmd_write(orig_pmd)) {
+                       if (dirty && !pmd_access_permitted(orig_pmd, WRITE)) {
                                ret = wp_huge_pmd(&vmf, orig_pmd);
                                if (!(ret & VM_FAULT_FALLBACK))
                                        return ret;