aboutsummaryrefslogtreecommitdiff
path: root/arch/powerpc/kernel/vdso64/gettimeofday.S
blob: 40ffd9b6cef7bf55fd81a6c62067afec4175d7c5 (plain)
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
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254

	/*
 * 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 */
	bl	V_LOCAL_FUNC(__do_get_xsec)	/* get xsec from tb & kernel */
	lis     r7,15			/* r7 = 1000000 = USEC_PER_SEC */
	ori     r7,r7,16960
	rldicl  r5,r4,44,20		/* r5 = sec = xsec / XSEC_PER_SEC */
	rldicr  r6,r5,20,43		/* r6 = sec * XSEC_PER_SEC */
	std	r5,TVAL64_TV_SEC(r11)	/* store sec in tv */
	subf	r0,r6,r4		/* r0 = xsec = (xsec - r6) */
	mulld   r0,r0,r7		/* usec = (xsec * USEC_PER_SEC) /
					 * XSEC_PER_SEC
					 */
	rldicl  r0,r0,44,20
	cmpldi	cr0,r10,0		/* check if tz is NULL */
	std	r0,TVAL64_TV_USEC(r11)	/* store usec in tv */
	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	r10,r3			/* r10 saves id */
	mr	r11,r4			/* r11 saves tp */
	bl	V_LOCAL_FUNC(__get_datapage)	/* get data page */
	beq	cr1,50f			/* if monotonic -> jump there */

	/*
	 * CLOCK_REALTIME
	 */

	bl	V_LOCAL_FUNC(__do_get_xsec)	/* get xsec from tb & kernel */

	lis     r7,15			/* r7 = 1000000 = USEC_PER_SEC */
	ori     r7,r7,16960
	rldicl  r5,r4,44,20		/* r5 = sec = xsec / XSEC_PER_SEC */
	rldicr  r6,r5,20,43		/* r6 = sec * XSEC_PER_SEC */
	std	r5,TSPC64_TV_SEC(r11)	/* store sec in tv */
	subf	r0,r6,r4		/* r0 = xsec = (xsec - r6) */
	mulld   r0,r0,r7		/* usec = (xsec * USEC_PER_SEC) /
					 * XSEC_PER_SEC
					 */
	rldicl  r0,r0,44,20
	mulli	r0,r0,1000		/* nsec = usec * 1000 */
	std	r0,TSPC64_TV_NSEC(r11)	/* store nsec in tp */

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

	/*
	 * CLOCK_MONOTONIC
	 */

50:	bl	V_LOCAL_FUNC(__do_get_xsec)	/* get xsec from tb & kernel */

	lis     r7,15			/* r7 = 1000000 = USEC_PER_SEC */
	ori     r7,r7,16960
	rldicl  r5,r4,44,20		/* r5 = sec = xsec / XSEC_PER_SEC */
	rldicr  r6,r5,20,43		/* r6 = sec * XSEC_PER_SEC */
	subf	r0,r6,r4		/* r0 = xsec = (xsec - r6) */
	mulld   r0,r0,r7		/* usec = (xsec * USEC_PER_SEC) /
					 * XSEC_PER_SEC
					 */
	rldicl  r6,r0,44,20
	mulli	r6,r6,1000		/* nsec = usec * 1000 */

	/* 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, r5,r6 contain our sec/nsec values.
	 * can be used
	 */

	lwa	r4,WTOM_CLOCK_SEC(r3)
	lwa	r7,WTOM_CLOCK_NSEC(r3)

	/* We now have our result in r4,r7. We create a fake dependency
	 * on that result and re-check the counter
	 */
	or	r9,r4,r7
	xor	r0,r9,r9
	add	r3,r3,r0
	ld	r0,CFG_TB_UPDATE_COUNT(r3)
        cmpld   cr0,r0,r8		/* check if updated */
	bne-	50b

	/* Calculate and store result. Note that this mimmics the C code,
	 * which may cause funny results if nsec goes negative... is that
	 * possible at all ?
	 */
	add	r4,r4,r5
	add	r7,r7,r6
	lis	r9,NSEC_PER_SEC@h
	ori	r9,r9,NSEC_PER_SEC@l
	cmpl	cr0,r7,r9
	cmpli	cr1,r7,0
	blt	1f
	subf	r7,r9,r7
	addi	r4,r4,1
1:	bge	cr1,1f
	addi	r4,r4,-1
	add	r7,r7,r9
1:	std	r4,TSPC64_TV_SEC(r11)
	std	r7,TSPC64_TV_NSEC(r11)

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

	/*
	 * syscall fallback
	 */
98:
	mtlr	r12
	mr	r3,r10
	mr	r4,r11
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 gettimeofday(), it returns the xsec
 * value in r4 and expects the datapage ptr (non clobbered)
 * in r3. clobbers r0,r4,r5,r6,r7,r8
 * When returning, r8 contains the counter value that can be reused
 */
V_FUNCTION_BEGIN(__do_get_xsec)
  .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(r7)
	ld	r9,CFG_TB_ORIG_STAMP(r3)
	subf	r7,r9,r7

	/* Scale result */
	ld	r5,CFG_TB_TO_XS(r3)
	mulhdu	r7,r7,r5

	/* Add stamp since epoch */
	ld	r6,CFG_STAMP_XSEC(r3)
	add	r4,r6,r7

	xor	r0,r4,r4
	add	r3,r3,r0
	ld	r0,CFG_TB_UPDATE_COUNT(r3)
        cmpld   cr0,r0,r8		/* check if updated */
	bne-	1b
	blr
  .cfi_endproc
V_FUNCTION_END(__do_get_xsec)