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 <[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]>
vieko · Nov 30, 2017 · 5c9d2d5 · 5c9d2d5
1 parent c7da82b
commit 5c9d2d5
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Showing 3 changed files with 5 additions and 5 deletions.
diff --git a/mm/gup.c b/mm/gup.c
@@ -66,7 +66,7 @@ static int follow_pfn_pte(struct vm_area_struct *vma, unsigned long address,
  */
 static inline bool can_follow_write_pte(pte_t pte, unsigned int flags)
 {
-	return pte_write(pte) ||
+	return pte_access_permitted(pte, WRITE) ||
 		((flags & FOLL_FORCE) && (flags & FOLL_COW) && pte_dirty(pte));
 }
 

diff --git a/mm/hmm.c b/mm/hmm.c
@@ -456,11 +456,11 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp,
 			continue;
 		}
 
-		if (write_fault && !pte_write(pte))
+		if (!pte_access_permitted(pte, write_fault))
 			goto fault;
 
 		pfns[i] = hmm_pfn_t_from_pfn(pte_pfn(pte)) | flag;
-		pfns[i] |= pte_write(pte) ? HMM_PFN_WRITE : 0;
+		pfns[i] |= pte_access_permitted(pte, WRITE) ? HMM_PFN_WRITE : 0;
 		continue;
 
 fault:

diff --git 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));