linux/arch/s390/kernel/vdso32/clock_getres.S
Martin Schwidefsky b020632e40 [S390] introduce vdso on s390
Add a vdso to speed up gettimeofday and clock_getres/clock_gettime for
CLOCK_REALTIME/CLOCK_MONOTONIC.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2008-12-25 13:38:55 +01:00

40 lines
1020 B
ArmAsm

/*
* Userland implementation of clock_getres() for 32 bits processes in a
* s390 kernel for use in the vDSO
*
* Copyright IBM Corp. 2008
* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License (version 2 only)
* as published by the Free Software Foundation.
*/
#include <asm/vdso.h>
#include <asm/asm-offsets.h>
#include <asm/unistd.h>
.text
.align 4
.globl __kernel_clock_getres
.type __kernel_clock_getres,@function
__kernel_clock_getres:
.cfi_startproc
chi %r2,CLOCK_REALTIME
je 0f
chi %r2,CLOCK_MONOTONIC
jne 3f
0: ltr %r3,%r3
jz 2f /* res == NULL */
basr %r1,0
1: l %r0,4f-1b(%r1)
xc 0(4,%r3),0(%r3) /* set tp->tv_sec to zero */
st %r0,4(%r3) /* store tp->tv_usec */
2: lhi %r2,0
br %r14
3: lhi %r1,__NR_clock_getres /* fallback to svc */
svc 0
br %r14
4: .long CLOCK_REALTIME_RES
.cfi_endproc
.size __kernel_clock_getres,.-__kernel_clock_getres