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/*
* Userland implementation of gettimeofday() for 64 bits processes in a
* ppc64 kernel for use in the vDSO
*
* Copyright (C) 2004 Benjamin Herrenschmuidt (benh@kernel.crashing.org),
* IBM Corp.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/config.h>
#include <asm/processor.h>
#include <asm/ppc_asm.h>
#include <asm/vdso.h>
#include <asm/asm-offsets.h>
.text
/*
* Exact prototype of gettimeofday
*
* int __kernel_gettimeofday(struct timeval *tv, struct timezone *tz);
*
*/
V_FUNCTION_BEGIN(__kernel_gettimeofday)
.cfi_startproc
mflr r12
.cfi_register lr,r12
mr r11,r3 /* r11 holds tv */
mr r10,r4 /* r10 holds tz */
bl V_LOCAL_FUNC(__get_datapage) /* get data page */
bl V_LOCAL_FUNC(__do_get_xsec) /* get xsec from tb & kernel */
lis r7,15 /* r7 = 1000000 = USEC_PER_SEC */
ori r7,r7,16960
rldicl r5,r4,44,20 /* r5 = sec = xsec / XSEC_PER_SEC */
rldicr r6,r5,20,43 /* r6 = sec * XSEC_PER_SEC */
std r5,TVAL64_TV_SEC(r11) /* store sec in tv */
subf r0,r6,r4 /* r0 = xsec = (xsec - r6) */
mulld r0,r0,r7 /* usec = (xsec * USEC_PER_SEC) / XSEC_PER_SEC */
rldicl r0,r0,44,20
cmpldi cr0,r10,0 /* check if tz is NULL */
std r0,TVAL64_TV_USEC(r11) /* store usec in tv */
beq 1f
lwz r4,CFG_TZ_MINUTEWEST(r3)/* fill tz */
lwz r5,CFG_TZ_DSTTIME(r3)
stw r4,TZONE_TZ_MINWEST(r10)
stw r5,TZONE_TZ_DSTTIME(r10)
1: mtlr r12
li r3,0 /* always success */
blr
.cfi_endproc
V_FUNCTION_END(__kernel_gettimeofday)
/*
* This is the core of gettimeofday(), it returns the xsec
* value in r4 and expects the datapage ptr (non clobbered)
* in r3. clobbers r0,r4,r5,r6,r7,r8
*/
V_FUNCTION_BEGIN(__do_get_xsec)
.cfi_startproc
/* check for update count & load values */
1: ld r7,CFG_TB_UPDATE_COUNT(r3)
andi. r0,r4,1 /* pending update ? loop */
bne- 1b
xor r0,r4,r4 /* create dependency */
add r3,r3,r0
/* Get TB & offset it */
mftb r8
ld r9,CFG_TB_ORIG_STAMP(r3)
subf r8,r9,r8
/* Scale result */
ld r5,CFG_TB_TO_XS(r3)
mulhdu r8,r8,r5
/* Add stamp since epoch */
ld r6,CFG_STAMP_XSEC(r3)
add r4,r6,r8
xor r0,r4,r4
add r3,r3,r0
ld r0,CFG_TB_UPDATE_COUNT(r3)
cmpld cr0,r0,r7 /* check if updated */
bne- 1b
blr
.cfi_endproc
V_FUNCTION_END(__do_get_xsec)
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