3 files changed, 24 insertions, 3 deletions

diff --git a/include/asm-i386/pgtable-2level.h b/include/asm-i386/pgtable-2level.h
index 27bde973abc7..2756d4b04c27 100644
--- a/include/asm-i386/pgtable-2level.h
+++ b/include/asm-i386/pgtable-2level.h
@@ -18,6 +18,9 @@
 #define set_pte_atomic(pteptr, pteval) set_pte(pteptr,pteval)
 #define set_pmd(pmdptr, pmdval) (*(pmdptr) = (pmdval))
 
+#define pte_clear(mm,addr,xp)   do { set_pte_at(mm, addr, xp, __pte(0)); } while (0)
+#define pmd_clear(xp)   do { set_pmd(xp, __pmd(0)); } while (0)
+
 #define ptep_get_and_clear(mm,addr,xp)  __pte(xchg(&(xp)->pte_low, 0))
 #define pte_same(a, b)          ((a).pte_low == (b).pte_low)
 #define pte_page(x)             pfn_to_page(pte_pfn(x))
diff --git a/include/asm-i386/pgtable-3level.h b/include/asm-i386/pgtable-3level.h
index 36a5aa63cbbf..dccb1b3337ad 100644
--- a/include/asm-i386/pgtable-3level.h
+++ b/include/asm-i386/pgtable-3level.h
@@ -85,6 +85,26 @@ static inline void pud_clear (pud_t * pud) { }
 #define pmd_offset(pud, address) ((pmd_t *) pud_page(*(pud)) + \
                         pmd_index(address))
 
+/*
+ * For PTEs and PDEs, we must clear the P-bit first when clearing a page table
+ * entry, so clear the bottom half first and enforce ordering with a compiler
+ * barrier.
+ */
+static inline void pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
+{
+        ptep->pte_low = 0;
+        smp_wmb();
+        ptep->pte_high = 0;
+}
+
+static inline void pmd_clear(pmd_t *pmd)
+{
+        u32 *tmp = (u32 *)pmd;
+        *tmp = 0;
+        smp_wmb();
+        *(tmp + 1) = 0;
+}
+
 static inline pte_t ptep_get_and_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
 {
         pte_t res;
diff --git a/include/asm-i386/pgtable.h b/include/asm-i386/pgtable.h
index ee056c41a9fb..672c3f76b9df 100644
--- a/include/asm-i386/pgtable.h
+++ b/include/asm-i386/pgtable.h
@@ -204,12 +204,10 @@ extern unsigned long long __PAGE_KERNEL, __PAGE_KERNEL_EXEC;
 extern unsigned long pg0[];
 
 #define pte_present(x)  ((x).pte_low & (_PAGE_PRESENT | _PAGE_PROTNONE))
-#define pte_clear(mm,addr,xp)   do { set_pte_at(mm, addr, xp, __pte(0)); } while (0)
 
 /* To avoid harmful races, pmd_none(x) should check only the lower when PAE */
 #define pmd_none(x)     (!(unsigned long)pmd_val(x))
 #define pmd_present(x)  (pmd_val(x) & _PAGE_PRESENT)
-#define pmd_clear(xp)   do { set_pmd(xp, __pmd(0)); } while (0)
 #define pmd_bad(x)      ((pmd_val(x) & (~PAGE_MASK & ~_PAGE_USER)) != _KERNPG_TABLE)
 
 
@@ -268,7 +266,7 @@ static inline pte_t ptep_get_and_clear_full(struct mm_struct *mm, unsigned long
         pte_t pte;
         if (full) {
                 pte = *ptep;
-                *ptep = __pte(0);
+                pte_clear(mm, addr, ptep);
         } else {
                 pte = ptep_get_and_clear(mm, addr, ptep);
         }