s390/time: always use stckf instead of stck if available

The store clock fast instruction saves a couple of instructions compared
to the store clock instruction. Always use stckf instead of stck if it
is available.

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

2 files changed, 12 insertions, 6 deletions

diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c
index 9475e682727f..d84181f1f5e8 100644
--- a/arch/s390/kernel/early.c
+++ b/arch/s390/kernel/early.c
@@ -374,8 +374,6 @@ static __init void detect_machine_facilities(void)
                 S390_lowcore.machine_flags |= MACHINE_FLAG_MVCOS;
         if (test_facility(40))
                 S390_lowcore.machine_flags |= MACHINE_FLAG_SPP;
-        if (test_facility(25))
-                S390_lowcore.machine_flags |= MACHINE_FLAG_STCKF;
 #endif
 }
 
diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S
index 3a633af72bae..444fd72e0787 100644
--- a/arch/s390/kernel/entry64.S
+++ b/arch/s390/kernel/entry64.S
@@ -148,6 +148,14 @@ _TIF_EXIT_SIE = (_TIF_SIGPENDING | _TIF_NEED_RESCHED | _TIF_MCCK_PENDING)
         ssm     __LC_RETURN_PSW
         .endm
 
+        .macro STCK savearea
+#if defined(CONFIG_64BIT) && !defined(CONFIG_MARCH_Z900) && !defined(CONFIG_MARCH_Z990)
+        .insn   s,0xb27c0000,\savearea          # store clock fast
+#else
+        .insn   s,0xb2050000,\savearea          # store clock
+#endif
+        .endm
+
         .section .kprobes.text, "ax"
 
 /*
@@ -458,7 +466,7 @@ pgm_svcper:
  * IO interrupt handler routine
  */
 ENTRY(io_int_handler)
-        stck    __LC_INT_CLOCK
+        STCK    __LC_INT_CLOCK
         stpt    __LC_ASYNC_ENTER_TIMER
         stmg    %r8,%r15,__LC_SAVE_AREA_ASYNC
         lg      %r10,__LC_LAST_BREAK
@@ -604,7 +612,7 @@ io_notify_resume:
  * External interrupt handler routine
  */
 ENTRY(ext_int_handler)
-        stck    __LC_INT_CLOCK
+        STCK    __LC_INT_CLOCK
         stpt    __LC_ASYNC_ENTER_TIMER
         stmg    %r8,%r15,__LC_SAVE_AREA_ASYNC
         lg      %r10,__LC_LAST_BREAK
@@ -639,7 +647,7 @@ ENTRY(psw_idle)
         larl    %r1,psw_idle_lpsw+4
         stg     %r1,__SF_EMPTY+8(%r15)
         larl    %r1,.Lvtimer_max
-        stck    __IDLE_ENTER(%r2)
+        STCK    __IDLE_ENTER(%r2)
         ltr     %r5,%r5
         stpt    __VQ_IDLE_ENTER(%r3)
         jz      psw_idle_lpsw
@@ -655,7 +663,7 @@ __critical_end:
  * Machine check handler routines
  */
 ENTRY(mcck_int_handler)
-        stck    __LC_MCCK_CLOCK
+        STCK    __LC_MCCK_CLOCK
         la      %r1,4095                # revalidate r1
         spt     __LC_CPU_TIMER_SAVE_AREA-4095(%r1)      # revalidate cpu timer
         lmg     %r0,%r15,__LC_GPREGS_SAVE_AREA-4095(%r1)# revalidate gprs