From 52499d93d6dec3872de3b982219af6d4c182a452 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Fri, 12 Feb 2016 12:40:31 +0100 Subject: [PATCH] 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 Signed-off-by: Martin Schwidefsky --- arch/s390/mm/maccess.c | 10 ++++++---- 1 file 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; -- 2.30.2