[S390] system call optimization.

After the in-kernel system call has been remove the system call path
can be optimized. The problem state bit of the old psw is always set
between system_call and sysc_do_svc. SAVE_ALL_SVC uses this information
to avoid two instructions.

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

1 files changed, 6 insertions, 1 deletions

diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S
index 685f11faa4bc..2a7b1304418b 100644
--- a/arch/s390/kernel/entry64.S
+++ b/arch/s390/kernel/entry64.S
@@ -99,6 +99,11 @@ _TIF_WORK_INT = (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK | _TIF_NEED_RESCHED | \
         larl    %r13,system_call
         .endm
 
+        .macro  SAVE_ALL_SVC psworg,savearea
+        la      %r12,\psworg
+        lg      %r15,__LC_KERNEL_STACK  # problem state -> load ksp
+        .endm
+
         .macro  SAVE_ALL_SYNC psworg,savearea
         la      %r12,\psworg
         tm      \psworg+1,0x01          # test problem state bit
@@ -207,7 +212,7 @@ system_call:
         STORE_TIMER __LC_SYNC_ENTER_TIMER
 sysc_saveall:
         SAVE_ALL_BASE __LC_SAVE_AREA
-        SAVE_ALL_SYNC __LC_SVC_OLD_PSW,__LC_SAVE_AREA
+        SAVE_ALL_SVC __LC_SVC_OLD_PSW,__LC_SAVE_AREA
         CREATE_STACK_FRAME __LC_SVC_OLD_PSW,__LC_SAVE_AREA
         llgh    %r7,__LC_SVC_INT_CODE   # get svc number from lowcore
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING