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s390/maccess: reduce stnsm instructions

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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>
This commit is contained in:
Heiko Carstens 2016-02-12 12:40:31 +01:00 committed by Martin Schwidefsky
parent f6c9b16023
commit 52499d93d6
1 changed files with 6 additions and 4 deletions
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arch/s390/mm/maccess.c
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@ -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;