aboutsummaryrefslogtreecommitdiff
path: root/arch/s390/kernel/vdso64/clock_gettime.S
blob: 6046b3bfca4622ea87bd1759bfa36e3f2d5b6d89 (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
/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Userland implementation of clock_gettime() for 64 bits processes in a
 * s390 kernel for use in the vDSO
 *
 *  Copyright IBM Corp. 2008
 *  Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
 */
#include <asm/vdso.h>
#include <asm/asm-offsets.h>
#include <asm/unistd.h>

	.text
	.align 4
	.globl __kernel_clock_gettime
	.type  __kernel_clock_gettime,@function
__kernel_clock_gettime:
	.cfi_startproc
	aghi	%r15,-16
	larl	%r5,_vdso_data
	cghi	%r2,__CLOCK_REALTIME_COARSE
	je	4f
	cghi	%r2,__CLOCK_REALTIME
	je	5f
	cghi	%r2,-3		/* Per-thread CPUCLOCK with PID=0, VIRT=1 */
	je	9f
	cghi	%r2,__CLOCK_MONOTONIC_COARSE
	je	3f
	cghi	%r2,__CLOCK_MONOTONIC
	jne	12f

	/* CLOCK_MONOTONIC */
0:	lg	%r4,__VDSO_UPD_COUNT(%r5)	/* load update counter */
	tmll	%r4,0x0001			/* pending update ? loop */
	jnz	0b
	stcke	0(%r15)				/* Store TOD clock */
	lgf	%r2,__VDSO_TK_SHIFT(%r5)	/* Timekeeper shift */
	lg	%r0,__VDSO_WTOM_SEC(%r5)
	lg	%r1,1(%r15)
	sg	%r1,__VDSO_XTIME_STAMP(%r5)	/* TOD - cycle_last */
	msgf	%r1,__VDSO_TK_MULT(%r5)		/*  * tk->mult */
	alg	%r1,__VDSO_WTOM_NSEC(%r5)
	srlg	%r1,%r1,0(%r2)			/*  >> tk->shift */
	clg	%r4,__VDSO_UPD_COUNT(%r5)	/* check update counter */
	jne	0b
	larl	%r5,13f
1:	clg	%r1,0(%r5)
	jl	2f
	slg	%r1,0(%r5)
	aghi	%r0,1
	j	1b
2:	stg	%r0,0(%r3)			/* store tp->tv_sec */
	stg	%r1,8(%r3)			/* store tp->tv_nsec */
	lghi	%r2,0
	aghi	%r15,16
	br	%r14

	/* CLOCK_MONOTONIC_COARSE */
3:	lg	%r4,__VDSO_UPD_COUNT(%r5)	/* load update counter */
	tmll	%r4,0x0001			/* pending update ? loop */
	jnz	3b
	lg	%r0,__VDSO_WTOM_CRS_SEC(%r5)
	lg	%r1,__VDSO_WTOM_CRS_NSEC(%r5)
	clg	%r4,__VDSO_UPD_COUNT(%r5)	/* check update counter */
	jne	3b
	j	2b

	/* CLOCK_REALTIME_COARSE */
4:	lg	%r4,__VDSO_UPD_COUNT(%r5)	/* load update counter */
	tmll	%r4,0x0001			/* pending update ? loop */
	jnz	4b
	lg	%r0,__VDSO_XTIME_CRS_SEC(%r5)
	lg	%r1,__VDSO_XTIME_CRS_NSEC(%r5)
	clg	%r4,__VDSO_UPD_COUNT(%r5)	/* check update counter */
	jne	4b
	j	7f

	/* CLOCK_REALTIME */
5:	lg	%r4,__VDSO_UPD_COUNT(%r5)	/* load update counter */
	tmll	%r4,0x0001			/* pending update ? loop */
	jnz	5b
	stcke	0(%r15)				/* Store TOD clock */
	lg	%r1,1(%r15)
	lg	%r0,__VDSO_TS_END(%r5)		/* TOD steering end time */
	slgr	%r0,%r1				/* now - ts_steering_end */
	ltgr	%r0,%r0				/* past end of steering ? */
	jm	17f
	srlg	%r0,%r0,15			/* 1 per 2^16 */
	tm	__VDSO_TS_DIR+3(%r5),0x01	/* steering direction? */
	jz	18f
	lcgr	%r0,%r0				/* negative TOD offset */
18:	algr	%r1,%r0				/* add steering offset */
17:	lgf	%r2,__VDSO_TK_SHIFT(%r5)	/* Timekeeper shift */
	sg	%r1,__VDSO_XTIME_STAMP(%r5)	/* TOD - cycle_last */
	msgf	%r1,__VDSO_TK_MULT(%r5)		/*  * tk->mult */
	alg	%r1,__VDSO_XTIME_NSEC(%r5)	/*  + tk->xtime_nsec */
	srlg	%r1,%r1,0(%r2)			/*  >> tk->shift */
	lg	%r0,__VDSO_XTIME_SEC(%r5)	/* tk->xtime_sec */
	clg	%r4,__VDSO_UPD_COUNT(%r5)	/* check update counter */
	jne	5b
	larl	%r5,13f
6:	clg	%r1,0(%r5)
	jl	7f
	slg	%r1,0(%r5)
	aghi	%r0,1
	j	6b
7:	stg	%r0,0(%r3)			/* store tp->tv_sec */
	stg	%r1,8(%r3)			/* store tp->tv_nsec */
	lghi	%r2,0
	aghi	%r15,16
	br	%r14

	/* CPUCLOCK_VIRT for this thread */
9:	lghi	%r4,0
	icm	%r0,15,__VDSO_ECTG_OK(%r5)
	jz	12f
	sacf	256				/* Magic ectg instruction */
	.insn	ssf,0xc80100000000,__VDSO_ECTG_BASE(4),__VDSO_ECTG_USER(4),4
	sacf	0
	algr	%r1,%r0				/* r1 = cputime as TOD value */
	mghi	%r1,1000			/* convert to nanoseconds */
	srlg	%r1,%r1,12			/* r1 = cputime in nanosec */
	lgr	%r4,%r1
	larl	%r5,13f
	srlg	%r1,%r1,9			/* divide by 1000000000 */
	mlg	%r0,8(%r5)
	srlg	%r0,%r0,11			/* r0 = tv_sec */
	stg	%r0,0(%r3)
	msg	%r0,0(%r5)			/* calculate tv_nsec */
	slgr	%r4,%r0				/* r4 = tv_nsec */
	stg	%r4,8(%r3)
	lghi	%r2,0
	aghi	%r15,16
	br	%r14

	/* Fallback to system call */
12:	lghi	%r1,__NR_clock_gettime
	svc	0
	aghi	%r15,16
	br	%r14

13:	.quad	1000000000
14:	.quad	19342813113834067
	.cfi_endproc
	.size	__kernel_clock_gettime,.-__kernel_clock_gettime