1 files changed, 159 insertions, 74 deletions

diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index ae44d2a3431..bd954e96f51 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -379,75 +379,183 @@ out_unmap:
 }
 EXPORT_SYMBOL_GPL(gmap_map_segment);
 
-/*
- * this function is assumed to be called with mmap_sem held
- */
-unsigned long __gmap_fault(unsigned long address, struct gmap *gmap)
+static unsigned long *gmap_table_walk(unsigned long address, struct gmap *gmap)
 {
-	unsigned long *table, vmaddr, segment;
-	struct mm_struct *mm;
-	struct gmap_pgtable *mp;
-	struct gmap_rmap *rmap;
-	struct vm_area_struct *vma;
-	struct page *page;
-	pgd_t *pgd;
-	pud_t *pud;
-	pmd_t *pmd;
+	unsigned long *table;
 
-	current->thread.gmap_addr = address;
-	mm = gmap->mm;
-	/* Walk the gmap address space page table */
 	table = gmap->table + ((address >> 53) & 0x7ff);
 	if (unlikely(*table & _REGION_ENTRY_INV))
-		return -EFAULT;
+		return ERR_PTR(-EFAULT);
 	table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
 	table = table + ((address >> 42) & 0x7ff);
 	if (unlikely(*table & _REGION_ENTRY_INV))
-		return -EFAULT;
+		return ERR_PTR(-EFAULT);
 	table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
 	table = table + ((address >> 31) & 0x7ff);
 	if (unlikely(*table & _REGION_ENTRY_INV))
-		return -EFAULT;
+		return ERR_PTR(-EFAULT);
 	table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
 	table = table + ((address >> 20) & 0x7ff);
+	return table;
+}
+
+/**
+ * __gmap_translate - translate a guest address to a user space address
+ * @address: guest address
+ * @gmap: pointer to guest mapping meta data structure
+ *
+ * Returns user space address which corresponds to the guest address or
+ * -EFAULT if no such mapping exists.
+ * This function does not establish potentially missing page table entries.
+ * The mmap_sem of the mm that belongs to the address space must be held
+ * when this function gets called.
+ */
+unsigned long __gmap_translate(unsigned long address, struct gmap *gmap)
+{
+	unsigned long *segment_ptr, vmaddr, segment;
+	struct gmap_pgtable *mp;
+	struct page *page;
 
+	current->thread.gmap_addr = address;
+	segment_ptr = gmap_table_walk(address, gmap);
+	if (IS_ERR(segment_ptr))
+		return PTR_ERR(segment_ptr);
 	/* Convert the gmap address to an mm address. */
-	segment = *table;
-	if (likely(!(segment & _SEGMENT_ENTRY_INV))) {
+	segment = *segment_ptr;
+	if (!(segment & _SEGMENT_ENTRY_INV)) {
 		page = pfn_to_page(segment >> PAGE_SHIFT);
 		mp = (struct gmap_pgtable *) page->index;
 		return mp->vmaddr | (address & ~PMD_MASK);
 	} else if (segment & _SEGMENT_ENTRY_RO) {
 		vmaddr = segment & _SEGMENT_ENTRY_ORIGIN;
-		vma = find_vma(mm, vmaddr);
-		if (!vma || vma->vm_start > vmaddr)
-			return -EFAULT;
+		return vmaddr | (address & ~PMD_MASK);
+	}
+	return -EFAULT;
+}
+EXPORT_SYMBOL_GPL(__gmap_translate);
 
-		/* Walk the parent mm page table */
-		pgd = pgd_offset(mm, vmaddr);
-		pud = pud_alloc(mm, pgd, vmaddr);
-		if (!pud)
-			return -ENOMEM;
-		pmd = pmd_alloc(mm, pud, vmaddr);
-		if (!pmd)
-			return -ENOMEM;
-		if (!pmd_present(*pmd) &&
-		    __pte_alloc(mm, vma, pmd, vmaddr))
-			return -ENOMEM;
-		/* pmd now points to a valid segment table entry. */
-		rmap = kmalloc(sizeof(*rmap), GFP_KERNEL|__GFP_REPEAT);
-		if (!rmap)
-			return -ENOMEM;
-		/* Link gmap segment table entry location to page table. */
-		page = pmd_page(*pmd);
-		mp = (struct gmap_pgtable *) page->index;
-		rmap->entry = table;
-		spin_lock(&mm->page_table_lock);
+/**
+ * gmap_translate - translate a guest address to a user space address
+ * @address: guest address
+ * @gmap: pointer to guest mapping meta data structure
+ *
+ * Returns user space address which corresponds to the guest address or
+ * -EFAULT if no such mapping exists.
+ * This function does not establish potentially missing page table entries.
+ */
+unsigned long gmap_translate(unsigned long address, struct gmap *gmap)
+{
+	unsigned long rc;
+
+	down_read(&gmap->mm->mmap_sem);
+	rc = __gmap_translate(address, gmap);
+	up_read(&gmap->mm->mmap_sem);
+	return rc;
+}
+EXPORT_SYMBOL_GPL(gmap_translate);
+
+static int gmap_connect_pgtable(unsigned long segment,
+				unsigned long *segment_ptr,
+				struct gmap *gmap)
+{
+	unsigned long vmaddr;
+	struct vm_area_struct *vma;
+	struct gmap_pgtable *mp;
+	struct gmap_rmap *rmap;
+	struct mm_struct *mm;
+	struct page *page;
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd;
+
+	mm = gmap->mm;
+	vmaddr = segment & _SEGMENT_ENTRY_ORIGIN;
+	vma = find_vma(mm, vmaddr);
+	if (!vma || vma->vm_start > vmaddr)
+		return -EFAULT;
+	/* Walk the parent mm page table */
+	pgd = pgd_offset(mm, vmaddr);
+	pud = pud_alloc(mm, pgd, vmaddr);
+	if (!pud)
+		return -ENOMEM;
+	pmd = pmd_alloc(mm, pud, vmaddr);
+	if (!pmd)
+		return -ENOMEM;
+	if (!pmd_present(*pmd) &&
+	    __pte_alloc(mm, vma, pmd, vmaddr))
+		return -ENOMEM;
+	/* pmd now points to a valid segment table entry. */
+	rmap = kmalloc(sizeof(*rmap), GFP_KERNEL|__GFP_REPEAT);
+	if (!rmap)
+		return -ENOMEM;
+	/* Link gmap segment table entry location to page table. */
+	page = pmd_page(*pmd);
+	mp = (struct gmap_pgtable *) page->index;
+	rmap->entry = segment_ptr;
+	spin_lock(&mm->page_table_lock);
+	if (*segment_ptr == segment) {
 		list_add(&rmap->list, &mp->mapper);
-		spin_unlock(&mm->page_table_lock);
 		/* Set gmap segment table entry to page table. */
-		*table = pmd_val(*pmd) & PAGE_MASK;
-		return vmaddr | (address & ~PMD_MASK);
+		*segment_ptr = pmd_val(*pmd) & PAGE_MASK;
+		rmap = NULL;
+	}
+	spin_unlock(&mm->page_table_lock);
+	kfree(rmap);
+	return 0;
+}
+
+static void gmap_disconnect_pgtable(struct mm_struct *mm, unsigned long *table)
+{
+	struct gmap_rmap *rmap, *next;
+	struct gmap_pgtable *mp;
+	struct page *page;
+	int flush;
+
+	flush = 0;
+	spin_lock(&mm->page_table_lock);
+	page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
+	mp = (struct gmap_pgtable *) page->index;
+	list_for_each_entry_safe(rmap, next, &mp->mapper, list) {
+		*rmap->entry =
+			_SEGMENT_ENTRY_INV | _SEGMENT_ENTRY_RO | mp->vmaddr;
+		list_del(&rmap->list);
+		kfree(rmap);
+		flush = 1;
+	}
+	spin_unlock(&mm->page_table_lock);
+	if (flush)
+		__tlb_flush_global();
+}
+
+/*
+ * this function is assumed to be called with mmap_sem held
+ */
+unsigned long __gmap_fault(unsigned long address, struct gmap *gmap)
+{
+	unsigned long *segment_ptr, segment;
+	struct gmap_pgtable *mp;
+	struct page *page;
+	int rc;
+
+	current->thread.gmap_addr = address;
+	segment_ptr = gmap_table_walk(address, gmap);
+	if (IS_ERR(segment_ptr))
+		return -EFAULT;
+	/* Convert the gmap address to an mm address. */
+	while (1) {
+		segment = *segment_ptr;
+		if (!(segment & _SEGMENT_ENTRY_INV)) {
+			/* Page table is present */
+			page = pfn_to_page(segment >> PAGE_SHIFT);
+			mp = (struct gmap_pgtable *) page->index;
+			return mp->vmaddr | (address & ~PMD_MASK);
+		}
+		if (!(segment & _SEGMENT_ENTRY_RO))
+			/* Nothing mapped in the gmap address space. */
+			break;
+		rc = gmap_connect_pgtable(segment, segment_ptr, gmap);
+		if (rc)
+			return rc;
 	}
 	return -EFAULT;
 }
@@ -511,29 +619,6 @@ void gmap_discard(unsigned long from, unsigned long to, struct gmap *gmap)
 }
 EXPORT_SYMBOL_GPL(gmap_discard);
 
-void gmap_unmap_notifier(struct mm_struct *mm, unsigned long *table)
-{
-	struct gmap_rmap *rmap, *next;
-	struct gmap_pgtable *mp;
-	struct page *page;
-	int flush;
-
-	flush = 0;
-	spin_lock(&mm->page_table_lock);
-	page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
-	mp = (struct gmap_pgtable *) page->index;
-	list_for_each_entry_safe(rmap, next, &mp->mapper, list) {
-		*rmap->entry =
-			_SEGMENT_ENTRY_INV | _SEGMENT_ENTRY_RO | mp->vmaddr;
-		list_del(&rmap->list);
-		kfree(rmap);
-		flush = 1;
-	}
-	spin_unlock(&mm->page_table_lock);
-	if (flush)
-		__tlb_flush_global();
-}
-
 static inline unsigned long *page_table_alloc_pgste(struct mm_struct *mm,
 						    unsigned long vmaddr)
 {
@@ -586,8 +671,8 @@ static inline void page_table_free_pgste(unsigned long *table)
 {
 }
 
-static inline void gmap_unmap_notifier(struct mm_struct *mm,
-					  unsigned long *table)
+static inline void gmap_disconnect_pgtable(struct mm_struct *mm,
+					   unsigned long *table)
 {
 }
 
@@ -653,7 +738,7 @@ void page_table_free(struct mm_struct *mm, unsigned long *table)
 	unsigned int bit, mask;
 
 	if (mm_has_pgste(mm)) {
-		gmap_unmap_notifier(mm, table);
+		gmap_disconnect_pgtable(mm, table);
 		return page_table_free_pgste(table);
 	}
 	/* Free 1K/2K page table fragment of a 4K page */
@@ -696,7 +781,7 @@ void page_table_free_rcu(struct mmu_gather *tlb, unsigned long *table)
 
 	mm = tlb->mm;
 	if (mm_has_pgste(mm)) {
-		gmap_unmap_notifier(mm, table);
+		gmap_disconnect_pgtable(mm, table);
 		table = (unsigned long *) (__pa(table) | FRAG_MASK);
 		tlb_remove_table(tlb, table);
 		return;