1 files changed, 53 insertions, 55 deletions

diff --git a/arch/s390/mm/pgalloc.c b/arch/s390/mm/pgalloc.c
index 3dd253f81a77..498c98a312f4 100644
--- a/arch/s390/mm/pgalloc.c
+++ b/arch/s390/mm/pgalloc.c
@@ -77,67 +77,65 @@ static void __crst_table_upgrade(void *arg)
 
 int crst_table_upgrade(struct mm_struct *mm, unsigned long end)
 {
-	unsigned long *table, *pgd;
-	int rc, notify;
+	unsigned long *pgd = NULL, *p4d = NULL, *__pgd;
+	unsigned long asce_limit = mm->context.asce_limit;
 
 	/* upgrade should only happen from 3 to 4, 3 to 5, or 4 to 5 levels */
-	VM_BUG_ON(mm->context.asce_limit < _REGION2_SIZE);
-	rc = 0;
-	notify = 0;
-	while (mm->context.asce_limit < end) {
-		table = crst_table_alloc(mm);
-		if (!table) {
-			rc = -ENOMEM;
-			break;
-		}
-		spin_lock_bh(&mm->page_table_lock);
-		pgd = (unsigned long *) mm->pgd;
-		if (mm->context.asce_limit == _REGION2_SIZE) {
-			crst_table_init(table, _REGION2_ENTRY_EMPTY);
-			p4d_populate(mm, (p4d_t *) table, (pud_t *) pgd);
-			mm->pgd = (pgd_t *) table;
-			mm->context.asce_limit = _REGION1_SIZE;
-			mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
-				_ASCE_USER_BITS | _ASCE_TYPE_REGION2;
-			mm_inc_nr_puds(mm);
-		} else {
-			crst_table_init(table, _REGION1_ENTRY_EMPTY);
-			pgd_populate(mm, (pgd_t *) table, (p4d_t *) pgd);
-			mm->pgd = (pgd_t *) table;
-			mm->context.asce_limit = -PAGE_SIZE;
-			mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
-				_ASCE_USER_BITS | _ASCE_TYPE_REGION1;
-		}
-		notify = 1;
-		spin_unlock_bh(&mm->page_table_lock);
-	}
-	if (notify)
-		on_each_cpu(__crst_table_upgrade, mm, 0);
-	return rc;
-}
+	VM_BUG_ON(asce_limit < _REGION2_SIZE);
 
-void crst_table_downgrade(struct mm_struct *mm)
-{
-	pgd_t *pgd;
+	if (end <= asce_limit)
+		return 0;
 
-	/* downgrade should only happen from 3 to 2 levels (compat only) */
-	VM_BUG_ON(mm->context.asce_limit != _REGION2_SIZE);
+	if (asce_limit == _REGION2_SIZE) {
+		p4d = crst_table_alloc(mm);
+		if (unlikely(!p4d))
+			goto err_p4d;
+		crst_table_init(p4d, _REGION2_ENTRY_EMPTY);
+	}
+	if (end > _REGION1_SIZE) {
+		pgd = crst_table_alloc(mm);
+		if (unlikely(!pgd))
+			goto err_pgd;
+		crst_table_init(pgd, _REGION1_ENTRY_EMPTY);
+	}
 
-	if (current->active_mm == mm) {
-		clear_user_asce();
-		__tlb_flush_mm(mm);
+	spin_lock_bh(&mm->page_table_lock);
+
+	/*
+	 * This routine gets called with mmap_sem lock held and there is
+	 * no reason to optimize for the case of otherwise. However, if
+	 * that would ever change, the below check will let us know.
+	 */
+	VM_BUG_ON(asce_limit != mm->context.asce_limit);
+
+	if (p4d) {
+		__pgd = (unsigned long *) mm->pgd;
+		p4d_populate(mm, (p4d_t *) p4d, (pud_t *) __pgd);
+		mm->pgd = (pgd_t *) p4d;
+		mm->context.asce_limit = _REGION1_SIZE;
+		mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
+			_ASCE_USER_BITS | _ASCE_TYPE_REGION2;
+		mm_inc_nr_puds(mm);
+	}
+	if (pgd) {
+		__pgd = (unsigned long *) mm->pgd;
+		pgd_populate(mm, (pgd_t *) pgd, (p4d_t *) __pgd);
+		mm->pgd = (pgd_t *) pgd;
+		mm->context.asce_limit = TASK_SIZE_MAX;
+		mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
+			_ASCE_USER_BITS | _ASCE_TYPE_REGION1;
 	}
 
-	pgd = mm->pgd;
-	mm_dec_nr_pmds(mm);
-	mm->pgd = (pgd_t *) (pgd_val(*pgd) & _REGION_ENTRY_ORIGIN);
-	mm->context.asce_limit = _REGION3_SIZE;
-	mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
-			   _ASCE_USER_BITS | _ASCE_TYPE_SEGMENT;
-	crst_table_free(mm, (unsigned long *) pgd);
+	spin_unlock_bh(&mm->page_table_lock);
 
-	if (current->active_mm == mm)
-		set_user_asce(mm);
+	on_each_cpu(__crst_table_upgrade, mm, 0);
+
+	return 0;
+
+err_pgd:
+	crst_table_free(mm, p4d);
+err_p4d:
+	return -ENOMEM;
 }
 
 static inline unsigned int atomic_xor_bits(atomic_t *v, unsigned int bits)
@@ -304,7 +302,7 @@ void __tlb_remove_table(void *_table)
 		mask >>= 24;
 		if (mask != 0)
 			break;
-		/* fallthrough */
+		fallthrough;
 	case 3:		/* 4K page table with pgstes */
 		if (mask & 3)
 			atomic_xor_bits(&page->_refcount, 3 << 24);
@@ -529,7 +527,7 @@ void base_asce_free(unsigned long asce)
 		base_region2_walk(table, 0, _REGION1_SIZE, 0);
 		break;
 	case _ASCE_TYPE_REGION1:
-		base_region1_walk(table, 0, -_PAGE_SIZE, 0);
+		base_region1_walk(table, 0, TASK_SIZE_MAX, 0);
 		break;
 	}
 	base_crst_free(table);