s390/maccess: reduce stnsm instructions

When fixing the DAT off bug ("s390: fix DAT off memory access, e.g.
on kdump") both Christian and I missed that we can save an additional
stnsm instruction.

This saves us a couple of cycles which could improve the speed of
memcpy_real.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 6 insertions, 4 deletions

diff --git a/arch/s390/mm/maccess.c b/arch/s390/mm/maccess.c
index 350b0acd7f52..792f9c63fbca 100644
--- a/arch/s390/mm/maccess.c
+++ b/arch/s390/mm/maccess.c
@@ -93,15 +93,17 @@ static int __memcpy_real(void *dest, void *src, size_t count)
  */
 int memcpy_real(void *dest, void *src, size_t count)
 {
+        int irqs_disabled, rc;
         unsigned long flags;
-        int rc;
 
         if (!count)
                 return 0;
-        local_irq_save(flags);
-        __arch_local_irq_stnsm(0xfbUL);
+        flags = __arch_local_irq_stnsm(0xf8UL);
+        irqs_disabled = arch_irqs_disabled_flags(flags);
+        if (!irqs_disabled)
+                trace_hardirqs_off();
         rc = __memcpy_real(dest, src, count);
-        if (!arch_irqs_disabled_flags(flags))
+        if (!irqs_disabled)
                 trace_hardirqs_on();
         __arch_local_irq_ssm(flags);
         return rc;