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|
/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* 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.
*/
#include <asm/processor.h>
#include <asm/ppc_asm.h>
#include <asm/vdso.h>
#include <asm/vdso_datapage.h>
#include <asm/asm-offsets.h>
#include <asm/unistd.h>
/* Offset for the low 32-bit part of a field of long type */
#ifdef CONFIG_PPC64
#define LOPART 4
#else
#define LOPART 0
#endif
.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 */
get_datapage r9, r0
beq 3f
LOAD_REG_IMMEDIATE(r7, 1000000) /* load up USEC_PER_SEC */
bl __do_get_tspec@local /* get sec/usec from tb & kernel */
stw r3,TVAL32_TV_SEC(r10)
stw r4,TVAL32_TV_USEC(r10)
3: cmplwi r11,0 /* check if tz is NULL */
mtlr r12
crclr cr0*4+so
li r3,0
beqlr
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)
blr
.cfi_endproc
V_FUNCTION_END(__kernel_gettimeofday)
/*
* Exact prototype of clock_gettime()
*
* int __kernel_clock_gettime(clockid_t clock_id, struct timespec *tp);
*
*/
V_FUNCTION_BEGIN(__kernel_clock_gettime)
.cfi_startproc
/* Check for supported clock IDs */
cmpli cr0,r3,CLOCK_REALTIME
cmpli cr1,r3,CLOCK_MONOTONIC
cror cr0*4+eq,cr0*4+eq,cr1*4+eq
cmpli cr5,r3,CLOCK_REALTIME_COARSE
cmpli cr6,r3,CLOCK_MONOTONIC_COARSE
cror cr5*4+eq,cr5*4+eq,cr6*4+eq
cror cr0*4+eq,cr0*4+eq,cr5*4+eq
bne cr0, .Lgettime_fallback
mflr r12 /* r12 saves lr */
.cfi_register lr,r12
mr r11,r4 /* r11 saves tp */
get_datapage r9, r0
LOAD_REG_IMMEDIATE(r7, NSEC_PER_SEC) /* load up NSEC_PER_SEC */
beq cr5, .Lcoarse_clocks
.Lprecise_clocks:
bl __do_get_tspec@local /* get sec/nsec from tb & kernel */
bne cr1, .Lfinish /* not monotonic -> all done */
/*
* CLOCK_MONOTONIC
*/
/* now we must fixup using wall to monotonic. We need to snapshot
* that value and do the counter trick again. Fortunately, we still
* have the counter value in r8 that was returned by __do_get_xsec.
* At this point, r3,r4 contain our sec/nsec values, r5 and r6
* can be used, r7 contains NSEC_PER_SEC.
*/
lwz r5,(WTOM_CLOCK_SEC+LOPART)(r9)
lwz r6,WTOM_CLOCK_NSEC(r9)
/* We now have our offset in r5,r6. We create a fake dependency
* on that value and re-check the counter
*/
or r0,r6,r5
xor r0,r0,r0
add r9,r9,r0
lwz r0,(CFG_TB_UPDATE_COUNT+LOPART)(r9)
cmpl cr0,r8,r0 /* check if updated */
bne- .Lprecise_clocks
b .Lfinish_monotonic
/*
* For coarse clocks we get data directly from the vdso data page, so
* we don't need to call __do_get_tspec, but we still need to do the
* counter trick.
*/
.Lcoarse_clocks:
lwz r8,(CFG_TB_UPDATE_COUNT+LOPART)(r9)
andi. r0,r8,1 /* pending update ? loop */
bne- .Lcoarse_clocks
add r9,r9,r0 /* r0 is already 0 */
/*
* CLOCK_REALTIME_COARSE, below values are needed for MONOTONIC_COARSE
* too
*/
lwz r3,STAMP_XTIME_SEC+LOPART(r9)
lwz r4,STAMP_XTIME_NSEC+LOPART(r9)
bne cr6,1f
/* CLOCK_MONOTONIC_COARSE */
lwz r5,(WTOM_CLOCK_SEC+LOPART)(r9)
lwz r6,WTOM_CLOCK_NSEC(r9)
/* check if counter has updated */
or r0,r6,r5
1: or r0,r0,r3
or r0,r0,r4
xor r0,r0,r0
add r3,r3,r0
lwz r0,CFG_TB_UPDATE_COUNT+LOPART(r9)
cmpl cr0,r0,r8 /* check if updated */
bne- .Lcoarse_clocks
/* Counter has not updated, so continue calculating proper values for
* sec and nsec if monotonic coarse, or just return with the proper
* values for realtime.
*/
bne cr6, .Lfinish
/* Calculate and store result. Note that this mimics the C code,
* which may cause funny results if nsec goes negative... is that
* possible at all ?
*/
.Lfinish_monotonic:
add r3,r3,r5
add r4,r4,r6
cmpw cr0,r4,r7
cmpwi cr1,r4,0
blt 1f
subf r4,r7,r4
addi r3,r3,1
1: bge cr1, .Lfinish
addi r3,r3,-1
add r4,r4,r7
.Lfinish:
stw r3,TSPC32_TV_SEC(r11)
stw r4,TSPC32_TV_NSEC(r11)
mtlr r12
crclr cr0*4+so
li r3,0
blr
/*
* syscall fallback
*/
.Lgettime_fallback:
li r0,__NR_clock_gettime
.cfi_restore lr
sc
blr
.cfi_endproc
V_FUNCTION_END(__kernel_clock_gettime)
/*
* Exact prototype of clock_getres()
*
* int __kernel_clock_getres(clockid_t clock_id, struct timespec *res);
*
*/
V_FUNCTION_BEGIN(__kernel_clock_getres)
.cfi_startproc
/* Check for supported clock IDs */
cmplwi cr0, r3, CLOCK_MAX
cmpwi cr1, r3, CLOCK_REALTIME_COARSE
cmpwi cr7, r3, CLOCK_MONOTONIC_COARSE
bgt cr0, 99f
LOAD_REG_IMMEDIATE(r5, KTIME_LOW_RES)
beq cr1, 1f
beq cr7, 1f
mflr r12
.cfi_register lr,r12
get_datapage r3, r0
lwz r5, CLOCK_HRTIMER_RES(r3)
mtlr r12
1: li r3,0
cmpli cr0,r4,0
crclr cr0*4+so
beqlr
stw r3,TSPC32_TV_SEC(r4)
stw r5,TSPC32_TV_NSEC(r4)
blr
/*
* syscall fallback
*/
99:
li r0,__NR_clock_getres
sc
blr
.cfi_endproc
V_FUNCTION_END(__kernel_clock_getres)
/*
* Exact prototype of time()
*
* time_t time(time *t);
*
*/
V_FUNCTION_BEGIN(__kernel_time)
.cfi_startproc
mflr r12
.cfi_register lr,r12
mr r11,r3 /* r11 holds t */
get_datapage r9, r0
lwz r3,STAMP_XTIME_SEC+LOPART(r9)
cmplwi r11,0 /* check if t is NULL */
mtlr r12
crclr cr0*4+so
beqlr
stw r3,0(r11) /* store result at *t */
blr
.cfi_endproc
V_FUNCTION_END(__kernel_time)
/*
* This is the core of clock_gettime() and gettimeofday(),
* it returns the current time in r3 (seconds) and r4.
* On entry, r7 gives the resolution of r4, either USEC_PER_SEC
* or NSEC_PER_SEC, giving r4 in microseconds or nanoseconds.
* It expects the datapage ptr in r9 and doesn't clobber it.
* It clobbers r0, r5 and r6.
* On return, r8 contains the counter value that can be reused.
* This clobbers cr0 but not any other cr field.
*/
__do_get_tspec:
.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+LOPART)(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)
cmplw cr0,r3,r0
bne- 2b
/* Subtract tb orig stamp and shift left 12 bits.
*/
subfc r4,r6,r4
subfe r0,r5,r3
slwi r0,r0,12
rlwimi. r0,r4,12,20,31
slwi r4,r4,12
/*
* Load scale factor & do multiplication.
* We only use the high 32 bits of the tb_to_xs value.
* Even with a 1GHz timebase clock, the high 32 bits of
* tb_to_xs will be at least 4 million, so the error from
* ignoring the low 32 bits will be no more than 0.25ppm.
* The error will just make the clock run very very slightly
* slow until the next time the kernel updates the VDSO data,
* at which point the clock will catch up to the kernel's value,
* so there is no long-term error accumulation.
*/
lwz r5,CFG_TB_TO_XS(r9) /* load values */
mulhwu r4,r4,r5
li r3,0
beq+ 4f /* skip high part computation if 0 */
mulhwu r3,r0,r5
mullw r5,r0,r5
addc r4,r4,r5
addze r3,r3
4:
/* At this point, we have seconds since the xtime stamp
* as a 32.32 fixed-point number in r3 and r4.
* Load & add the xtime stamp.
*/
lwz r5,STAMP_XTIME_SEC+LOPART(r9)
lwz r6,STAMP_SEC_FRAC(r9)
addc r4,r4,r6
adde r3,r3,r5
/* We create a fake dependency on the result in r3/r4
* and re-check the counter
*/
or r6,r4,r3
xor r0,r6,r6
add r9,r9,r0
lwz r0,(CFG_TB_UPDATE_COUNT+LOPART)(r9)
cmplw cr0,r8,r0 /* check if updated */
bne- 1b
mulhwu r4,r4,r7 /* convert to micro or nanoseconds */
blr
.cfi_endproc
|
