x86: unify PAE/non-PAE pgd_ctor

The constructors for PAE and non-PAE pgd_ctors are more or less
identical, and can be made into the same function.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: William Irwin <wli@holomorphy.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/mm/pgtable_32.c

@@ -219,50 +219,39 @@ static inline void pgd_list_del(pgd_t *pgd)
 	list_del(&page->lru);
 }
 
+#define UNSHARED_PTRS_PER_PGD				\
+	(SHARED_KERNEL_PMD ? USER_PTRS_PER_PGD : PTRS_PER_PGD)
 
-
-#if (PTRS_PER_PMD == 1)
-/* Non-PAE pgd constructor */
-static void pgd_ctor(void *pgd)
+static void pgd_ctor(void *p)
 {
+	pgd_t *pgd = p;
 	unsigned long flags;
 
-	/* !PAE, no pagetable sharing */
+	/* Clear usermode parts of PGD */
 	memset(pgd, 0, USER_PTRS_PER_PGD*sizeof(pgd_t));
 
 	spin_lock_irqsave(&pgd_lock, flags);
 
-	/* must happen under lock */
-	clone_pgd_range((pgd_t *)pgd + USER_PTRS_PER_PGD,
+	/* If the pgd points to a shared pagetable level (either the
+	   ptes in non-PAE, or shared PMD in PAE), then just copy the
+	   references from swapper_pg_dir. */
+	if (PAGETABLE_LEVELS == 2 ||
+	    (PAGETABLE_LEVELS == 3 && SHARED_KERNEL_PMD)) {
+		clone_pgd_range(pgd + USER_PTRS_PER_PGD,
 				swapper_pg_dir + USER_PTRS_PER_PGD,
 				KERNEL_PGD_PTRS);
 		paravirt_alloc_pd_clone(__pa(pgd) >> PAGE_SHIFT,
 					__pa(swapper_pg_dir) >> PAGE_SHIFT,
 					USER_PTRS_PER_PGD,
 					KERNEL_PGD_PTRS);
-	pgd_list_add(pgd);
-	spin_unlock_irqrestore(&pgd_lock, flags);
-}
-#else  /* PTRS_PER_PMD > 1 */
-/* PAE pgd constructor */
-static void pgd_ctor(void *pgd)
-{
-	/* PAE, kernel PMD may be shared */
-
-	if (SHARED_KERNEL_PMD) {
-		clone_pgd_range((pgd_t *)pgd + USER_PTRS_PER_PGD,
-				swapper_pg_dir + USER_PTRS_PER_PGD,
-				KERNEL_PGD_PTRS);
-	} else {
-		unsigned long flags;
+	}
 
-		memset(pgd, 0, USER_PTRS_PER_PGD*sizeof(pgd_t));
-		spin_lock_irqsave(&pgd_lock, flags);
+	/* list required to sync kernel mapping updates */
+	if (!SHARED_KERNEL_PMD)
 		pgd_list_add(pgd);
+
 	spin_unlock_irqrestore(&pgd_lock, flags);
-	}
 }
-#endif	/* PTRS_PER_PMD */
 
 static void pgd_dtor(void *pgd)
 {
@@ -276,9 +265,6 @@ static void pgd_dtor(void *pgd)
 	spin_unlock_irqrestore(&pgd_lock, flags);
 }
 
-#define UNSHARED_PTRS_PER_PGD				\
-	(SHARED_KERNEL_PMD ? USER_PTRS_PER_PGD : PTRS_PER_PGD)
-
 #ifdef CONFIG_X86_PAE
 /*
  * Mop up any pmd pages which may still be attached to the pgd.