1/*
  2 * Userland implementation of clock_gettime() for 64 bits processes in a
  3 * s390 kernel for use in the vDSO
  4 *
  5 *  Copyright IBM Corp. 2008
  6 *  Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
  7 *
  8 * This program is free software; you can redistribute it and/or modify
  9 * it under the terms of the GNU General Public License (version 2 only)
 10 * as published by the Free Software Foundation.
 11 */
 12#include <asm/vdso.h>
 13#include <asm/asm-offsets.h>
 14#include <asm/unistd.h>
 15
 16	.text
 17	.align 4
 18	.globl __kernel_clock_gettime
 19	.type  __kernel_clock_gettime,@function
 20__kernel_clock_gettime:
 21	.cfi_startproc
 22	larl	%r5,_vdso_data
 23	cghi	%r2,__CLOCK_REALTIME
 24	je	4f
 25	cghi	%r2,-2		/* CLOCK_THREAD_CPUTIME_ID for this thread */
 26	je	9f
 27	cghi	%r2,__CLOCK_MONOTONIC
 28	jne	12f
 29
 30	/* CLOCK_MONOTONIC */
 31	ltgr	%r3,%r3
 32	jz	3f				/* tp == NULL */
 330:	lg	%r4,__VDSO_UPD_COUNT(%r5)	/* load update counter */
 34	tmll	%r4,0x0001			/* pending update ? loop */
 35	jnz	0b
 36	stck	48(%r15)			/* Store TOD clock */
 37	lg	%r1,48(%r15)
 38	sg	%r1,__VDSO_XTIME_STAMP(%r5)	/* TOD - cycle_last */
 39	msgf	%r1,__VDSO_NTP_MULT(%r5)	/*  * NTP adjustment */
 40	srlg	%r1,%r1,12			/* cyc2ns(clock,cycle_delta) */
 41	alg	%r1,__VDSO_XTIME_NSEC(%r5)	/*  + xtime */
 42	lg	%r0,__VDSO_XTIME_SEC(%r5)
 43	alg	%r1,__VDSO_WTOM_NSEC(%r5)	/*  + wall_to_monotonic */
 44	alg	%r0,__VDSO_WTOM_SEC(%r5)
 45	clg	%r4,__VDSO_UPD_COUNT(%r5)	/* check update counter */
 46	jne	0b
 47	larl	%r5,13f
 481:	clg	%r1,0(%r5)
 49	jl	2f
 50	slg	%r1,0(%r5)
 51	aghi	%r0,1
 52	j	1b
 532:	stg	%r0,0(%r3)			/* store tp->tv_sec */
 54	stg	%r1,8(%r3)			/* store tp->tv_nsec */
 553:	lghi	%r2,0
 56	br	%r14
 57
 58	/* CLOCK_REALTIME */
 594:	ltr	%r3,%r3				/* tp == NULL */
 60	jz	8f
 615:	lg	%r4,__VDSO_UPD_COUNT(%r5)	/* load update counter */
 62	tmll	%r4,0x0001			/* pending update ? loop */
 63	jnz	5b
 64	stck	48(%r15)			/* Store TOD clock */
 65	lg	%r1,48(%r15)
 66	sg	%r1,__VDSO_XTIME_STAMP(%r5)	/* TOD - cycle_last */
 67	msgf	%r1,__VDSO_NTP_MULT(%r5)	/*  * NTP adjustment */
 68	srlg	%r1,%r1,12			/* cyc2ns(clock,cycle_delta) */
 69	alg	%r1,__VDSO_XTIME_NSEC(%r5)	/*  + xtime */
 70	lg	%r0,__VDSO_XTIME_SEC(%r5)
 71	clg	%r4,__VDSO_UPD_COUNT(%r5)	/* check update counter */
 72	jne	5b
 73	larl	%r5,13f
 746:	clg	%r1,0(%r5)
 75	jl	7f
 76	slg	%r1,0(%r5)
 77	aghi	%r0,1
 78	j	6b
 797:	stg	%r0,0(%r3)			/* store tp->tv_sec */
 80	stg	%r1,8(%r3)			/* store tp->tv_nsec */
 818:	lghi	%r2,0
 82	br	%r14
 83
 84	/* CLOCK_THREAD_CPUTIME_ID for this thread */
 859:	icm	%r0,15,__VDSO_ECTG_OK(%r5)
 86	jz	12f
 87	ear	%r2,%a4
 88	llilh	%r4,0x0100
 89	sar	%a4,%r4
 90	lghi	%r4,0
 91	epsw	%r5,0
 92	sacf	512				/* Magic ectg instruction */
 93	.insn	ssf,0xc80100000000,__VDSO_ECTG_BASE(4),__VDSO_ECTG_USER(4),4
 94	tml	%r5,0x4000
 95	jo	11f
 96	tml	%r5,0x8000
 97	jno	10f
 98	sacf	256
 99	j	11f
10010:	sacf	0
10111:	sar	%a4,%r2
102	algr	%r1,%r0				/* r1 = cputime as TOD value */
103	mghi	%r1,1000			/* convert to nanoseconds */
104	srlg	%r1,%r1,12			/* r1 = cputime in nanosec */
105	lgr	%r4,%r1
106	larl	%r5,13f
107	srlg	%r1,%r1,9			/* divide by 1000000000 */
108	mlg	%r0,8(%r5)
109	srlg	%r0,%r0,11			/* r0 = tv_sec */
110	stg	%r0,0(%r3)
111	msg	%r0,0(%r5)			/* calculate tv_nsec */
112	slgr	%r4,%r0				/* r4 = tv_nsec */
113	stg	%r4,8(%r3)
114	lghi	%r2,0
115	br	%r14
116
117	/* Fallback to system call */
11812:	lghi	%r1,__NR_clock_gettime
119	svc	0
120	br	%r14
121
12213:	.quad	1000000000
12314:	.quad	19342813113834067
124	.cfi_endproc
125	.size	__kernel_clock_gettime,.-__kernel_clock_gettime