[thirdparty/linux.git] / arch / powerpc / kernel / vdso32 / gettimeofday.S

/* 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
Commit	Line	Data
2874c5fd	1	/* SPDX-License-Identifier: GPL-2.0-or-later */
a7f290da BH	2	/*
	3	* Userland implementation of gettimeofday() for 32 bits processes in a
	4	* ppc64 kernel for use in the vDSO
	5	*
	6	* Copyright (C) 2004 Benjamin Herrenschmuidt (benh@kernel.crashing.org,
	7	* IBM Corp.
a7f290da	8	*/
a7f290da BH	9	#include <asm/processor.h>
	10	#include <asm/ppc_asm.h>
	11	#include <asm/vdso.h>
ec0895f0	12	#include <asm/vdso_datapage.h>
a7f290da BH	13	#include <asm/asm-offsets.h>
	14	#include <asm/unistd.h>
	15
597bc5c0 PM	16	/* Offset for the low 32-bit part of a field of long type */
	17	#ifdef CONFIG_PPC64
	18	#define LOPART 4
	19	#else
	20	#define LOPART 0
	21	#endif
	22
a7f290da BH	23	.text
	24	/*
	25	* Exact prototype of gettimeofday
	26	*
	27	* int __kernel_gettimeofday(struct timeval tv, struct timezone tz);
	28	*
	29	*/
	30	V_FUNCTION_BEGIN(__kernel_gettimeofday)
	31	.cfi_startproc
	32	mflr r12
	33	.cfi_register lr,r12
	34
bfc2eae0	35	mr. r10,r3 /* r10 saves tv */
a7f290da	36	mr r11,r4 /* r11 saves tz */
ec0895f0	37	get_datapage r9, r0
74609f45	38	beq 3f
6e2f9e9c	39	LOAD_REG_IMMEDIATE(r7, 1000000) /* load up USEC_PER_SEC */
8fd63a9e PM	40	bl __do_get_tspec@local /* get sec/usec from tb & kernel */
	41	stw r3,TVAL32_TV_SEC(r10)
	42	stw r4,TVAL32_TV_USEC(r10)
a7f290da	43
74609f45	44	3: cmplwi r11,0 /* check if tz is NULL */
bfc2eae0 CL	45	mtlr r12
	46	crclr cr0*4+so
	47	li r3,0
	48	beqlr
	49
a7f290da BH	50	lwz r4,CFG_TZ_MINUTEWEST(r9)/* fill tz */
	51	lwz r5,CFG_TZ_DSTTIME(r9)
	52	stw r4,TZONE_TZ_MINWEST(r11)
	53	stw r5,TZONE_TZ_DSTTIME(r11)
	54
a7f290da	55	blr
a7f290da BH	56	.cfi_endproc
	57	V_FUNCTION_END(__kernel_gettimeofday)
	58
	59	/*
	60	* Exact prototype of clock_gettime()
	61	*
	62	* int __kernel_clock_gettime(clockid_t clock_id, struct timespec *tp);
	63	*
	64	*/
	65	V_FUNCTION_BEGIN(__kernel_clock_gettime)
	66	.cfi_startproc
	67	/* Check for supported clock IDs */
	68	cmpli cr0,r3,CLOCK_REALTIME
	69	cmpli cr1,r3,CLOCK_MONOTONIC
0c37ec2a	70	cror cr04+eq,cr04+eq,cr1*4+eq
654abc69 CL	71
	72	cmpli cr5,r3,CLOCK_REALTIME_COARSE
	73	cmpli cr6,r3,CLOCK_MONOTONIC_COARSE
	74	cror cr54+eq,cr54+eq,cr6*4+eq
	75
	76	cror cr04+eq,cr04+eq,cr5*4+eq
	77	bne cr0, .Lgettime_fallback
a7f290da BH	78
	79	mflr r12 /* r12 saves lr */
	80	.cfi_register lr,r12
a7f290da	81	mr r11,r4 /* r11 saves tp */
ec0895f0	82	get_datapage r9, r0
6e2f9e9c	83	LOAD_REG_IMMEDIATE(r7, NSEC_PER_SEC) /* load up NSEC_PER_SEC */
654abc69 CL	84	beq cr5, .Lcoarse_clocks
	85	.Lprecise_clocks:
	86	bl __do_get_tspec@local /* get sec/nsec from tb & kernel */
	87	bne cr1, .Lfinish /* not monotonic -> all done */
a7f290da BH	88
	89	/*
	90	* CLOCK_MONOTONIC
	91	*/
	92
a7f290da BH	93	/* now we must fixup using wall to monotonic. We need to snapshot
	94	* that value and do the counter trick again. Fortunately, we still
	95	* have the counter value in r8 that was returned by __do_get_xsec.
597bc5c0 PM	96	* At this point, r3,r4 contain our sec/nsec values, r5 and r6
597bc5c0 PM	97	* can be used, r7 contains NSEC_PER_SEC.
a7f290da BH	98	*/
a7f290da BH	99
dd9a994f	100	lwz r5,(WTOM_CLOCK_SEC+LOPART)(r9)
597bc5c0	101	lwz r6,WTOM_CLOCK_NSEC(r9)
a7f290da	102
597bc5c0 PM	103	/* We now have our offset in r5,r6. We create a fake dependency
597bc5c0 PM	104	* on that value and re-check the counter
a7f290da	105	*/
597bc5c0 PM	106	or r0,r6,r5
597bc5c0 PM	107	xor r0,r0,r0
a7f290da	108	add r9,r9,r0
597bc5c0	109	lwz r0,(CFG_TB_UPDATE_COUNT+LOPART)(r9)
a7f290da	110	cmpl cr0,r8,r0 /* check if updated */
654abc69 CL	111	bne- .Lprecise_clocks
	112	b .Lfinish_monotonic
	113
	114	/*
	115	* For coarse clocks we get data directly from the vdso data page, so
	116	* we don't need to call __do_get_tspec, but we still need to do the
	117	* counter trick.
	118	*/
	119	.Lcoarse_clocks:
	120	lwz r8,(CFG_TB_UPDATE_COUNT+LOPART)(r9)
	121	andi. r0,r8,1 /* pending update ? loop */
	122	bne- .Lcoarse_clocks
	123	add r9,r9,r0 /* r0 is already 0 */
	124
	125	/*
	126	* CLOCK_REALTIME_COARSE, below values are needed for MONOTONIC_COARSE
	127	* too
	128	*/
	129	lwz r3,STAMP_XTIME_SEC+LOPART(r9)
	130	lwz r4,STAMP_XTIME_NSEC+LOPART(r9)
	131	bne cr6,1f
	132
	133	/* CLOCK_MONOTONIC_COARSE */
	134	lwz r5,(WTOM_CLOCK_SEC+LOPART)(r9)
	135	lwz r6,WTOM_CLOCK_NSEC(r9)
	136
	137	/* check if counter has updated */
	138	or r0,r6,r5
	139	1: or r0,r0,r3
	140	or r0,r0,r4
	141	xor r0,r0,r0
	142	add r3,r3,r0
	143	lwz r0,CFG_TB_UPDATE_COUNT+LOPART(r9)
	144	cmpl cr0,r0,r8 /* check if updated */
	145	bne- .Lcoarse_clocks
	146
	147	/* Counter has not updated, so continue calculating proper values for
	148	* sec and nsec if monotonic coarse, or just return with the proper
	149	* values for realtime.
	150	*/
	151	bne cr6, .Lfinish
a7f290da	152
597bc5c0	153	/* Calculate and store result. Note that this mimics the C code,
a7f290da BH	154	* which may cause funny results if nsec goes negative... is that
	155	* possible at all ?
	156	*/
654abc69	157	.Lfinish_monotonic:
597bc5c0 PM	158	add r3,r3,r5
	159	add r4,r4,r6
	160	cmpw cr0,r4,r7
	161	cmpwi cr1,r4,0
a7f290da	162	blt 1f
597bc5c0	163	subf r4,r7,r4
a7f290da	164	addi r3,r3,1
654abc69	165	1: bge cr1, .Lfinish
0c37ec2a	166	addi r3,r3,-1
597bc5c0 PM	167	add r4,r4,r7
597bc5c0 PM	168
654abc69 CL	169	.Lfinish:
654abc69 CL	170	stw r3,TSPC32_TV_SEC(r11)
a7f290da BH	171	stw r4,TSPC32_TV_NSEC(r11)
	172
	173	mtlr r12
5d66da3d	174	crclr cr0*4+so
a7f290da BH	175	li r3,0
	176	blr
	177
	178	/*
	179	* syscall fallback
	180	*/
654abc69	181	.Lgettime_fallback:
a7f290da	182	li r0,__NR_clock_gettime
56d20861	183	.cfi_restore lr
a7f290da BH	184	sc
	185	blr
	186	.cfi_endproc
	187	V_FUNCTION_END(__kernel_clock_gettime)
	188
	189
	190	/*
	191	* Exact prototype of clock_getres()
	192	*
	193	* int __kernel_clock_getres(clockid_t clock_id, struct timespec *res);
	194	*
	195	*/
	196	V_FUNCTION_BEGIN(__kernel_clock_getres)
	197	.cfi_startproc
	198	/* Check for supported clock IDs */
e33ffc95 CL	199	cmplwi cr0, r3, CLOCK_MAX
	200	cmpwi cr1, r3, CLOCK_REALTIME_COARSE
	201	cmpwi cr7, r3, CLOCK_MONOTONIC_COARSE
	202	bgt cr0, 99f
	203	LOAD_REG_IMMEDIATE(r5, KTIME_LOW_RES)
	204	beq cr1, 1f
	205	beq cr7, 1f
a7f290da	206
55226345 VF	207	mflr r12
55226345 VF	208	.cfi_register lr,r12
ec0895f0	209	get_datapage r3, r0
55226345 VF	210	lwz r5, CLOCK_HRTIMER_RES(r3)
55226345 VF	211	mtlr r12
e33ffc95	212	1: li r3,0
a7f290da	213	cmpli cr0,r4,0
5d66da3d	214	crclr cr0*4+so
a7f290da	215	beqlr
a7f290da BH	216	stw r3,TSPC32_TV_SEC(r4)
	217	stw r5,TSPC32_TV_NSEC(r4)
	218	blr
	219
	220	/*
e963b7a2	221	* syscall fallback
a7f290da BH	222	*/
a7f290da BH	223	99:
e963b7a2 CL	224	li r0,__NR_clock_getres
e963b7a2 CL	225	sc
a7f290da BH	226	blr
	227	.cfi_endproc
	228	V_FUNCTION_END(__kernel_clock_getres)
	229
	230
fcb41a20 AZ	231	/*
	232	* Exact prototype of time()
	233	*
	234	* time_t time(time *t);
	235	*
	236	*/
	237	V_FUNCTION_BEGIN(__kernel_time)
	238	.cfi_startproc
	239	mflr r12
	240	.cfi_register lr,r12
	241
	242	mr r11,r3 /* r11 holds t */
ec0895f0	243	get_datapage r9, r0
fcb41a20	244
1c11ca7a	245	lwz r3,STAMP_XTIME_SEC+LOPART(r9)
fcb41a20 AZ	246
fcb41a20 AZ	247	cmplwi r11,0 /* check if t is NULL */
bfc2eae0	248	mtlr r12
fcb41a20	249	crclr cr0*4+so
bfc2eae0 CL	250	beqlr
bfc2eae0 CL	251	stw r3,0(r11) /* store result at t /
fcb41a20 AZ	252	blr
	253	.cfi_endproc
	254	V_FUNCTION_END(__kernel_time)
	255
a7f290da	256	/*
8fd63a9e PM	257	* This is the core of clock_gettime() and gettimeofday(),
	258	* it returns the current time in r3 (seconds) and r4.
	259	* On entry, r7 gives the resolution of r4, either USEC_PER_SEC
	260	* or NSEC_PER_SEC, giving r4 in microseconds or nanoseconds.
597bc5c0	261	* It expects the datapage ptr in r9 and doesn't clobber it.
8fd63a9e	262	* It clobbers r0, r5 and r6.
597bc5c0 PM	263	* On return, r8 contains the counter value that can be reused.
	264	* This clobbers cr0 but not any other cr field.
	265	*/
	266	__do_get_tspec:
	267	.cfi_startproc
	268	/* Check for update count & load values. We use the low
	269	* order 32 bits of the update count
	270	*/
	271	1: lwz r8,(CFG_TB_UPDATE_COUNT+LOPART)(r9)
	272	andi. r0,r8,1 /* pending update ? loop */
	273	bne- 1b
	274	xor r0,r8,r8 /* create dependency */
	275	add r9,r9,r0
	276
	277	/* Load orig stamp (offset to TB) */
	278	lwz r5,CFG_TB_ORIG_STAMP(r9)
	279	lwz r6,(CFG_TB_ORIG_STAMP+4)(r9)
	280
	281	/* Get a stable TB value */
72e4b2cd CL	282	2: MFTBU(r3)
	283	MFTBL(r4)
	284	MFTBU(r0)
8fd63a9e	285	cmplw cr0,r3,r0
597bc5c0 PM	286	bne- 2b
	287
	288	/* Subtract tb orig stamp and shift left 12 bits.
	289	*/
8fd63a9e	290	subfc r4,r6,r4
597bc5c0 PM	291	subfe r0,r5,r3
597bc5c0 PM	292	slwi r0,r0,12
8fd63a9e PM	293	rlwimi. r0,r4,12,20,31
8fd63a9e PM	294	slwi r4,r4,12
597bc5c0	295
8fd63a9e PM	296	/*
	297	* Load scale factor & do multiplication.
	298	* We only use the high 32 bits of the tb_to_xs value.
	299	* Even with a 1GHz timebase clock, the high 32 bits of
	300	* tb_to_xs will be at least 4 million, so the error from
	301	* ignoring the low 32 bits will be no more than 0.25ppm.
	302	* The error will just make the clock run very very slightly
	303	* slow until the next time the kernel updates the VDSO data,
	304	* at which point the clock will catch up to the kernel's value,
	305	* so there is no long-term error accumulation.
	306	*/
597bc5c0	307	lwz r5,CFG_TB_TO_XS(r9) /* load values */
8fd63a9e	308	mulhwu r4,r4,r5
597bc5c0 PM	309	li r3,0
	310
	311	beq+ 4f /* skip high part computation if 0 */
	312	mulhwu r3,r0,r5
8fd63a9e	313	mullw r5,r0,r5
597bc5c0 PM	314	addc r4,r4,r5
597bc5c0 PM	315	addze r3,r3
8fd63a9e PM	316	4:
	317	/* At this point, we have seconds since the xtime stamp
	318	* as a 32.32 fixed-point number in r3 and r4.
	319	* Load & add the xtime stamp.
597bc5c0	320	*/
1c11ca7a	321	lwz r5,STAMP_XTIME_SEC+LOPART(r9)
8fd63a9e PM	322	lwz r6,STAMP_SEC_FRAC(r9)
8fd63a9e PM	323	addc r4,r4,r6
597bc5c0 PM	324	adde r3,r3,r5
597bc5c0 PM	325
8fd63a9e PM	326	/* We create a fake dependency on the result in r3/r4
8fd63a9e PM	327	* and re-check the counter
597bc5c0 PM	328	*/
	329	or r6,r4,r3
	330	xor r0,r6,r6
	331	add r9,r9,r0
	332	lwz r0,(CFG_TB_UPDATE_COUNT+LOPART)(r9)
8fd63a9e	333	cmplw cr0,r8,r0 /* check if updated */
597bc5c0 PM	334	bne- 1b
597bc5c0 PM	335
8fd63a9e	336	mulhwu r4,r4,r7 /* convert to micro or nanoseconds */
597bc5c0 PM	337
	338	blr
	339	.cfi_endproc