141 lines
3.5 KiB
ArmAsm
141 lines
3.5 KiB
ArmAsm
/*
|
|
* Userland implementation of gettimeofday() for 32 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>
|
|
#include <asm/unistd.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 r10,r3 /* r10 saves tv */
|
|
mr r11,r4 /* r11 saves tz */
|
|
bl __get_datapage@local /* get data page */
|
|
mr r9, r3 /* datapage ptr in r9 */
|
|
bl __do_get_xsec@local /* get xsec from tb & kernel */
|
|
bne- 2f /* out of line -> do syscall */
|
|
|
|
/* seconds are xsec >> 20 */
|
|
rlwinm r5,r4,12,20,31
|
|
rlwimi r5,r3,12,0,19
|
|
stw r5,TVAL32_TV_SEC(r10)
|
|
|
|
/* get remaining xsec and convert to usec. we scale
|
|
* up remaining xsec by 12 bits and get the top 32 bits
|
|
* of the multiplication
|
|
*/
|
|
rlwinm r5,r4,12,0,19
|
|
lis r6,1000000@h
|
|
ori r6,r6,1000000@l
|
|
mulhwu r5,r5,r6
|
|
stw r5,TVAL32_TV_USEC(r10)
|
|
|
|
cmpli cr0,r11,0 /* check if tz is NULL */
|
|
beq 1f
|
|
lwz r4,CFG_TZ_MINUTEWEST(r9)/* fill tz */
|
|
lwz r5,CFG_TZ_DSTTIME(r9)
|
|
stw r4,TZONE_TZ_MINWEST(r11)
|
|
stw r5,TZONE_TZ_DSTTIME(r11)
|
|
|
|
1: mtlr r12
|
|
li r3,0
|
|
blr
|
|
|
|
2: mr r3,r10
|
|
mr r4,r11
|
|
li r0,__NR_gettimeofday
|
|
sc
|
|
b 1b
|
|
.cfi_endproc
|
|
V_FUNCTION_END(__kernel_gettimeofday)
|
|
|
|
/*
|
|
* This is the core of gettimeofday(), it returns the xsec
|
|
* value in r3 & r4 and expects the datapage ptr (non clobbered)
|
|
* in r9. clobbers r0,r4,r5,r6,r7,r8
|
|
*/
|
|
__do_get_xsec:
|
|
.cfi_startproc
|
|
/* Check for update count & load values. We use the low
|
|
* order 32 bits of the update count
|
|
*/
|
|
1: lwz r8,(CFG_TB_UPDATE_COUNT+4)(r9)
|
|
andi. r0,r8,1 /* pending update ? loop */
|
|
bne- 1b
|
|
xor r0,r8,r8 /* create dependency */
|
|
add r9,r9,r0
|
|
|
|
/* Load orig stamp (offset to TB) */
|
|
lwz r5,CFG_TB_ORIG_STAMP(r9)
|
|
lwz r6,(CFG_TB_ORIG_STAMP+4)(r9)
|
|
|
|
/* Get a stable TB value */
|
|
2: mftbu r3
|
|
mftbl r4
|
|
mftbu r0
|
|
cmpl cr0,r3,r0
|
|
bne- 2b
|
|
|
|
/* Substract tb orig stamp. If the high part is non-zero, we jump to the
|
|
* slow path which call the syscall. If it's ok, then we have our 32 bits
|
|
* tb_ticks value in r7
|
|
*/
|
|
subfc r7,r6,r4
|
|
subfe. r0,r5,r3
|
|
bne- 3f
|
|
|
|
/* Load scale factor & do multiplication */
|
|
lwz r5,CFG_TB_TO_XS(r9) /* load values */
|
|
lwz r6,(CFG_TB_TO_XS+4)(r9)
|
|
mulhwu r4,r7,r5
|
|
mulhwu r6,r7,r6
|
|
mullw r0,r7,r5
|
|
addc r6,r6,r0
|
|
|
|
/* At this point, we have the scaled xsec value in r4 + XER:CA
|
|
* we load & add the stamp since epoch
|
|
*/
|
|
lwz r5,CFG_STAMP_XSEC(r9)
|
|
lwz r6,(CFG_STAMP_XSEC+4)(r9)
|
|
adde r4,r4,r6
|
|
addze r3,r5
|
|
|
|
/* We now have our result in r3,r4. We create a fake dependency
|
|
* on that result and re-check the counter
|
|
*/
|
|
xor r0,r4,r4
|
|
add r9,r9,r0
|
|
lwz r0,(CFG_TB_UPDATE_COUNT+4)(r9)
|
|
cmpl cr0,r8,r0 /* check if updated */
|
|
bne- 1b
|
|
|
|
/* Warning ! The caller expects CR:EQ to be set to indicate a
|
|
* successful calculation (so it won't fallback to the syscall
|
|
* method). We have overriden that CR bit in the counter check,
|
|
* but fortunately, the loop exit condition _is_ CR:EQ set, so
|
|
* we can exit safely here. If you change this code, be careful
|
|
* of that side effect.
|
|
*/
|
|
3: blr
|
|
.cfi_endproc
|