From: Martin Schwidefsky 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 --- arch/s390/kernel/entry.S | 7 ++++++- arch/s390/kernel/entry64.S | 7 ++++++- 2 files changed, 12 insertions(+), 2 deletions(-) Index: quilt-2.6/arch/s390/kernel/entry64.S =================================================================== --- quilt-2.6.orig/arch/s390/kernel/entry64.S +++ quilt-2.6/arch/s390/kernel/entry64.S @@ -99,6 +99,11 @@ _TIF_WORK_INT = (_TIF_SIGPENDING | _TIF_ 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 Index: quilt-2.6/arch/s390/kernel/entry.S =================================================================== --- quilt-2.6.orig/arch/s390/kernel/entry.S +++ quilt-2.6/arch/s390/kernel/entry.S @@ -107,6 +107,11 @@ STACK_SIZE = 1 << STACK_SHIFT l %r13,__LC_SVC_NEW_PSW+4 # load &system_call to %r13 .endm + .macro SAVE_ALL_SVC psworg,savearea + la %r12,\psworg + l %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 @@ -218,7 +223,7 @@ 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 lh %r7,0x8a # get svc number from lowcore #ifdef CONFIG_VIRT_CPU_ACCOUNTING -- blue skies, Martin. "Reality continues to ruin my life." - Calvin. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/