/*
   * 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)
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License (version 2 only)
   * as published by the Free Software Foundation.
   */
  #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 */

  	lgf	%r2,__VDSO_TK_SHIFT(%r5)	/* Timekeeper shift */

  	lg	%r1,1(%r15)

  	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:	icm	%r0,15,__VDSO_ECTG_OK(%r5)
  	jz	12f
  	ear	%r2,%a4
  	llilh	%r4,0x0100
  	sar	%a4,%r4
  	lghi	%r4,0

  	epsw	%r5,0

  	sacf	512				/* Magic ectg instruction */
  	.insn	ssf,0xc80100000000,__VDSO_ECTG_BASE(4),__VDSO_ECTG_USER(4),4

  	tml	%r5,0x4000
  	jo	11f
  	tml	%r5,0x8000
  	jno	10f
  	sacf	256
  	j	11f
  10:	sacf	0
  11:	sar	%a4,%r2

  	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