s390/mm,tlb: correct tlb flush on page table upgrade

The IDTE instruction used to flush TLB entries for a specific address
space uses the address-space-control element (ASCE) to identify
affected TLB entries. The upgrade of a page table adds a new top
level page table which changes the ASCE. The TLB entries associated
with the old ASCE need to be flushed and the ASCE for the address space
needs to be replaced synchronously on all CPUs which currently use it.
The concept of a lazy ASCE update with an exception handler is broken.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 2 insertions, 10 deletions

diff --git a/arch/s390/mm/mmap.c b/arch/s390/mm/mmap.c
index 4002329..6bcb045 100644
--- a/arch/s390/mm/mmap.c
+++ b/arch/s390/mm/mmap.c
@@ -101,18 +101,12 @@ void arch_pick_mmap_layout(struct mm_struct *mm)
 
 int s390_mmap_check(unsigned long addr, unsigned long len, unsigned long flags)
 {
-	int rc;
-
 	if (is_compat_task() || (TASK_SIZE >= (1UL << 53)))
 		return 0;
 	if (!(flags & MAP_FIXED))
 		addr = 0;
-	if ((addr + len) >= TASK_SIZE) {
-		rc = crst_table_upgrade(current->mm, 1UL << 53);
-		if (rc)
-			return rc;
-		update_mm(current->mm, current);
-	}
+	if ((addr + len) >= TASK_SIZE)
+		return crst_table_upgrade(current->mm, 1UL << 53);
 	return 0;
 }
 
@@ -132,7 +126,6 @@ s390_get_unmapped_area(struct file *filp, unsigned long addr,
 		rc = crst_table_upgrade(mm, 1UL << 53);
 		if (rc)
 			return (unsigned long) rc;
-		update_mm(mm, current);
 		area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
 	}
 	return area;
@@ -155,7 +148,6 @@ s390_get_unmapped_area_topdown(struct file *filp, const unsigned long addr,
 		rc = crst_table_upgrade(mm, 1UL << 53);
 		if (rc)
 			return (unsigned long) rc;
-		update_mm(mm, current);
 		area = arch_get_unmapped_area_topdown(filp, addr, len,
 						      pgoff, flags);
 	}