forked from luck/tmp_suning_uos_patched
859deea949
The Cell CPU timebase has an erratum. When reading the entire 64 bits of the timebase with one mftb instruction, there is a handful of cycles window during which one might read a value with the low order 32 bits already reset to 0x00000000 but the high order bits not yet incremeted by one. This fixes it by reading the timebase again until the low order 32 bits is no longer 0. That might introduce occasional latencies if hitting mftb just at the wrong time, but no more than 70ns on a cell blade, and that was considered acceptable. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Acked-by: Olof Johansson <olof@lixom.net> Signed-off-by: Paul Mackerras <paulus@samba.org>
255 lines
6.0 KiB
ArmAsm
255 lines
6.0 KiB
ArmAsm
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/*
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* Userland implementation of gettimeofday() for 64 bits processes in a
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* ppc64 kernel for use in the vDSO
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*
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* Copyright (C) 2004 Benjamin Herrenschmuidt (benh@kernel.crashing.org),
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* IBM Corp.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <asm/processor.h>
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#include <asm/ppc_asm.h>
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#include <asm/vdso.h>
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#include <asm/asm-offsets.h>
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#include <asm/unistd.h>
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.text
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/*
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* Exact prototype of gettimeofday
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*
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* int __kernel_gettimeofday(struct timeval *tv, struct timezone *tz);
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*
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*/
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V_FUNCTION_BEGIN(__kernel_gettimeofday)
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.cfi_startproc
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mflr r12
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.cfi_register lr,r12
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mr r11,r3 /* r11 holds tv */
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mr r10,r4 /* r10 holds tz */
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bl V_LOCAL_FUNC(__get_datapage) /* get data page */
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bl V_LOCAL_FUNC(__do_get_xsec) /* get xsec from tb & kernel */
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lis r7,15 /* r7 = 1000000 = USEC_PER_SEC */
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ori r7,r7,16960
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rldicl r5,r4,44,20 /* r5 = sec = xsec / XSEC_PER_SEC */
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rldicr r6,r5,20,43 /* r6 = sec * XSEC_PER_SEC */
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std r5,TVAL64_TV_SEC(r11) /* store sec in tv */
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subf r0,r6,r4 /* r0 = xsec = (xsec - r6) */
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mulld r0,r0,r7 /* usec = (xsec * USEC_PER_SEC) /
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* XSEC_PER_SEC
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*/
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rldicl r0,r0,44,20
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cmpldi cr0,r10,0 /* check if tz is NULL */
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std r0,TVAL64_TV_USEC(r11) /* store usec in tv */
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beq 1f
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lwz r4,CFG_TZ_MINUTEWEST(r3)/* fill tz */
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lwz r5,CFG_TZ_DSTTIME(r3)
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stw r4,TZONE_TZ_MINWEST(r10)
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stw r5,TZONE_TZ_DSTTIME(r10)
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1: mtlr r12
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crclr cr0*4+so
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li r3,0 /* always success */
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blr
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.cfi_endproc
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V_FUNCTION_END(__kernel_gettimeofday)
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/*
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* Exact prototype of clock_gettime()
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*
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* int __kernel_clock_gettime(clockid_t clock_id, struct timespec *tp);
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*
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*/
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V_FUNCTION_BEGIN(__kernel_clock_gettime)
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.cfi_startproc
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/* Check for supported clock IDs */
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cmpwi cr0,r3,CLOCK_REALTIME
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cmpwi cr1,r3,CLOCK_MONOTONIC
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cror cr0*4+eq,cr0*4+eq,cr1*4+eq
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bne cr0,99f
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mflr r12 /* r12 saves lr */
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.cfi_register lr,r12
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mr r10,r3 /* r10 saves id */
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mr r11,r4 /* r11 saves tp */
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bl V_LOCAL_FUNC(__get_datapage) /* get data page */
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beq cr1,50f /* if monotonic -> jump there */
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/*
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* CLOCK_REALTIME
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*/
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bl V_LOCAL_FUNC(__do_get_xsec) /* get xsec from tb & kernel */
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lis r7,15 /* r7 = 1000000 = USEC_PER_SEC */
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ori r7,r7,16960
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rldicl r5,r4,44,20 /* r5 = sec = xsec / XSEC_PER_SEC */
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rldicr r6,r5,20,43 /* r6 = sec * XSEC_PER_SEC */
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std r5,TSPC64_TV_SEC(r11) /* store sec in tv */
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subf r0,r6,r4 /* r0 = xsec = (xsec - r6) */
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mulld r0,r0,r7 /* usec = (xsec * USEC_PER_SEC) /
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* XSEC_PER_SEC
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*/
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rldicl r0,r0,44,20
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mulli r0,r0,1000 /* nsec = usec * 1000 */
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std r0,TSPC64_TV_NSEC(r11) /* store nsec in tp */
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mtlr r12
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crclr cr0*4+so
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li r3,0
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blr
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/*
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* CLOCK_MONOTONIC
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*/
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50: bl V_LOCAL_FUNC(__do_get_xsec) /* get xsec from tb & kernel */
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lis r7,15 /* r7 = 1000000 = USEC_PER_SEC */
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ori r7,r7,16960
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rldicl r5,r4,44,20 /* r5 = sec = xsec / XSEC_PER_SEC */
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rldicr r6,r5,20,43 /* r6 = sec * XSEC_PER_SEC */
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subf r0,r6,r4 /* r0 = xsec = (xsec - r6) */
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mulld r0,r0,r7 /* usec = (xsec * USEC_PER_SEC) /
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* XSEC_PER_SEC
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*/
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rldicl r6,r0,44,20
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mulli r6,r6,1000 /* nsec = usec * 1000 */
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/* now we must fixup using wall to monotonic. We need to snapshot
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* that value and do the counter trick again. Fortunately, we still
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* have the counter value in r8 that was returned by __do_get_xsec.
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* At this point, r5,r6 contain our sec/nsec values.
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* can be used
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*/
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lwa r4,WTOM_CLOCK_SEC(r3)
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lwa r7,WTOM_CLOCK_NSEC(r3)
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/* We now have our result in r4,r7. We create a fake dependency
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* on that result and re-check the counter
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*/
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or r9,r4,r7
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xor r0,r9,r9
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add r3,r3,r0
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ld r0,CFG_TB_UPDATE_COUNT(r3)
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cmpld cr0,r0,r8 /* check if updated */
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bne- 50b
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/* Calculate and store result. Note that this mimmics the C code,
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* which may cause funny results if nsec goes negative... is that
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* possible at all ?
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*/
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add r4,r4,r5
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add r7,r7,r6
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lis r9,NSEC_PER_SEC@h
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ori r9,r9,NSEC_PER_SEC@l
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cmpl cr0,r7,r9
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cmpli cr1,r7,0
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blt 1f
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subf r7,r9,r7
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addi r4,r4,1
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1: bge cr1,1f
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addi r4,r4,-1
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add r7,r7,r9
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1: std r4,TSPC64_TV_SEC(r11)
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std r7,TSPC64_TV_NSEC(r11)
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mtlr r12
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crclr cr0*4+so
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li r3,0
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blr
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/*
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* syscall fallback
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*/
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98:
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mtlr r12
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mr r3,r10
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mr r4,r11
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99:
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li r0,__NR_clock_gettime
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sc
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blr
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.cfi_endproc
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V_FUNCTION_END(__kernel_clock_gettime)
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/*
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* Exact prototype of clock_getres()
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*
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* int __kernel_clock_getres(clockid_t clock_id, struct timespec *res);
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*
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*/
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V_FUNCTION_BEGIN(__kernel_clock_getres)
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.cfi_startproc
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/* Check for supported clock IDs */
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cmpwi cr0,r3,CLOCK_REALTIME
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cmpwi cr1,r3,CLOCK_MONOTONIC
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cror cr0*4+eq,cr0*4+eq,cr1*4+eq
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bne cr0,99f
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li r3,0
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cmpli cr0,r4,0
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crclr cr0*4+so
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beqlr
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lis r5,CLOCK_REALTIME_RES@h
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ori r5,r5,CLOCK_REALTIME_RES@l
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std r3,TSPC64_TV_SEC(r4)
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std r5,TSPC64_TV_NSEC(r4)
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blr
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/*
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* syscall fallback
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*/
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99:
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li r0,__NR_clock_getres
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sc
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blr
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.cfi_endproc
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V_FUNCTION_END(__kernel_clock_getres)
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/*
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* This is the core of gettimeofday(), it returns the xsec
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* value in r4 and expects the datapage ptr (non clobbered)
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* in r3. clobbers r0,r4,r5,r6,r7,r8
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* When returning, r8 contains the counter value that can be reused
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*/
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V_FUNCTION_BEGIN(__do_get_xsec)
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.cfi_startproc
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/* check for update count & load values */
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1: ld r8,CFG_TB_UPDATE_COUNT(r3)
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andi. r0,r8,1 /* pending update ? loop */
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bne- 1b
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xor r0,r8,r8 /* create dependency */
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add r3,r3,r0
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/* Get TB & offset it. We use the MFTB macro which will generate
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* workaround code for Cell.
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*/
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MFTB(r7)
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ld r9,CFG_TB_ORIG_STAMP(r3)
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subf r7,r9,r7
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/* Scale result */
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ld r5,CFG_TB_TO_XS(r3)
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mulhdu r7,r7,r5
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/* Add stamp since epoch */
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ld r6,CFG_STAMP_XSEC(r3)
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add r4,r6,r7
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xor r0,r4,r4
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add r3,r3,r0
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ld r0,CFG_TB_UPDATE_COUNT(r3)
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cmpld cr0,r0,r8 /* check if updated */
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bne- 1b
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blr
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.cfi_endproc
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V_FUNCTION_END(__do_get_xsec)
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