aboutsummaryrefslogtreecommitdiffstats
path: root/arch/powerpc/kernel/vdso64/gettimeofday.S
blob: e97a9a0dc4ac3af3545118d6dbc190d515be4e0f (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
/*
 * 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 <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	r11,r3			/* r11 holds tv */
	mr	r10,r4			/* r10 holds tz */
	bl	V_LOCAL_FUNC(__get_datapage)	/* get data page */
	cmpldi	r11,0			/* check if tv is NULL */
	beq	2f
	lis	r7,1000000@ha		/* load up USEC_PER_SEC */
	addi	r7,r7,1000000@l
	bl	V_LOCAL_FUNC(__do_get_tspec) /* get sec/us from tb & kernel */
	std	r4,TVAL64_TV_SEC(r11)	/* store sec in tv */
	std	r5,TVAL64_TV_USEC(r11)	/* store usec in tv */
2:	cmpldi	r10,0			/* check if tz is NULL */
	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
	crclr	cr0*4+so
	li	r3,0			/* always success */
	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 */
	cmpwi	cr0,r3,CLOCK_REALTIME
	cmpwi	cr1,r3,CLOCK_MONOTONIC
	cror	cr0*4+eq,cr0*4+eq,cr1*4+eq
	bne	cr0,99f

	mflr	r12			/* r12 saves lr */
  .cfi_register lr,r12
	mr	r11,r4			/* r11 saves tp */
	bl	V_LOCAL_FUNC(__get_datapage)	/* get data page */
	lis	r7,NSEC_PER_SEC@h	/* want nanoseconds */
	ori	r7,r7,NSEC_PER_SEC@l
50:	bl	V_LOCAL_FUNC(__do_get_tspec)	/* get time from tb & kernel */
	bne	cr1,80f			/* if 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_tspec.
	 * At this point, r4,r5 contain our sec/nsec values.
	 */

	lwa	r6,WTOM_CLOCK_SEC(r3)
	lwa	r9,WTOM_CLOCK_NSEC(r3)

	/* We now have our result in r6,r9. We create a fake dependency
	 * on that result and re-check the counter
	 */
	or	r0,r6,r9
	xor	r0,r0,r0
	add	r3,r3,r0
	ld	r0,CFG_TB_UPDATE_COUNT(r3)
        cmpld   cr0,r0,r8		/* check if updated */
	bne-	50b

	/* Add wall->monotonic offset and check for overflow or underflow.
	 */
	add	r4,r4,r6
	add	r5,r5,r9
	cmpd	cr0,r5,r7
	cmpdi	cr1,r5,0
	blt	1f
	subf	r5,r7,r5
	addi	r4,r4,1
1:	bge	cr1,80f
	addi	r4,r4,-1
	add	r5,r5,r7

80:	std	r4,TSPC64_TV_SEC(r11)
	std	r5,TSPC64_TV_NSEC(r11)

	mtlr	r12
	crclr	cr0*4+so
	li	r3,0
	blr

	/*
	 * syscall fallback
	 */
99:
	li	r0,__NR_clock_gettime
	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 */
	cmpwi	cr0,r3,CLOCK_REALTIME
	cmpwi	cr1,r3,CLOCK_MONOTONIC
	cror	cr0*4+eq,cr0*4+eq,cr1*4+eq
	bne	cr0,99f

	li	r3,0
	cmpli	cr0,r4,0
	crclr	cr0*4+so
	beqlr
	lis	r5,CLOCK_REALTIME_RES@h
	ori	r5,r5,CLOCK_REALTIME_RES@l
	std	r3,TSPC64_TV_SEC(r4)
	std	r5,TSPC64_TV_NSEC(r4)
	blr

	/*
	 * syscall fallback
	 */
99:
	li	r0,__NR_clock_getres
	sc
	blr
  .cfi_endproc
V_FUNCTION_END(__kernel_clock_getres)


/*
 * This is the core of clock_gettime() and gettimeofday(),
 * it returns the current time in r4 (seconds) and r5.
 * On entry, r7 gives the resolution of r5, either USEC_PER_SEC
 * or NSEC_PER_SEC, giving r5 in microseconds or nanoseconds.
 * It expects the datapage ptr in r3 and doesn't clobber it.
 * It clobbers r0, r6 and r9.
 * On return, r8 contains the counter value that can be reused.
 * This clobbers cr0 but not any other cr field.
 */
V_FUNCTION_BEGIN(__do_get_tspec)
  .cfi_startproc
	/* check for update count & load values */
1:	ld	r8,CFG_TB_UPDATE_COUNT(r3)
	andi.	r0,r8,1			/* pending update ? loop */
	bne-	1b
	xor	r0,r8,r8		/* create dependency */
	add	r3,r3,r0

	/* Get TB & offset it. We use the MFTB macro which will generate
	 * workaround code for Cell.
	 */
	MFTB(r6)
	ld	r9,CFG_TB_ORIG_STAMP(r3)
	subf	r6,r9,r6

	/* Scale result */
	ld	r5,CFG_TB_TO_XS(r3)
	sldi	r6,r6,12		/* compute time since stamp_xtime */
	mulhdu	r6,r6,r5		/* in units of 2^-32 seconds */

	/* Add stamp since epoch */
	ld	r4,STAMP_XTIME+TSPC64_TV_SEC(r3)
	lwz	r5,STAMP_SEC_FRAC(r3)
	or	r0,r4,r5
	or	r0,r0,r6
	xor	r0,r0,r0
	add	r3,r3,r0
	ld	r0,CFG_TB_UPDATE_COUNT(r3)
	cmpld   r0,r8			/* check if updated */
	bne-	1b			/* reload if so */

	/* convert to seconds & nanoseconds and add to stamp */
	add	r6,r6,r5		/* add on fractional seconds of xtime */
	mulhwu	r5,r6,r7		/* compute micro or nanoseconds and */
	srdi	r6,r6,32		/* seconds since stamp_xtime */
	clrldi	r5,r5,32
	add	r4,r4,r6
	blr
  .cfi_endproc
V_FUNCTION_END(__do_get_tspec)