s390/mm: fix gmap tlb flush issues

__tlb_flush_asce() should never be used if multiple asce belong to a mm.

As this function changes mm logic determining if local or global tlb
flushes will be neded, we might end up flushing only the gmap asce on all
CPUs and a follow up mm asce flushes will only flush on the local CPU,
although that asce ran on multiple CPUs.

The missing tlb flushes will provoke strange faults in user space and even
low address protections in user space, crashing the kernel.

Fixes: 1b948d6caec4 ("s390/mm,tlb: optimize TLB flushing for zEC12")
Cc: stable@vger.kernel.org # 3.15+
Reported-by: Sascha Silbe <silbe@linux.vnet.ibm.com>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index 69466f6055c2..063c721ec0dc 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -85,7 +85,7 @@ EXPORT_SYMBOL_GPL(gmap_alloc);
 static void gmap_flush_tlb(struct gmap *gmap)
 {
         if (MACHINE_HAS_IDTE)
-                __tlb_flush_asce(gmap->mm, gmap->asce);
+                __tlb_flush_idte(gmap->asce);
         else
                 __tlb_flush_global();
 }
@@ -124,7 +124,7 @@ void gmap_free(struct gmap *gmap)
 
         /* Flush tlb. */
         if (MACHINE_HAS_IDTE)
-                __tlb_flush_asce(gmap->mm, gmap->asce);
+                __tlb_flush_idte(gmap->asce);
         else
                 __tlb_flush_global();