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75c7b6f3f6
On STP sync events the TOD clock will jump in time, either forward or backward. The TOD clocksource claims to be continuous but in case of an STP sync with a negative offset it is not. Subtract the offset injected by the STP sync check from the result of the TOD clocksource to make it continuous again. Add code to drift the offset towards zero with a fixed rate, steering 1 second in ~9 hours. Suggested-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
159 lines
4.1 KiB
ArmAsm
159 lines
4.1 KiB
ArmAsm
/*
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* Userland implementation of clock_gettime() for 64 bits processes in a
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* s390 kernel for use in the vDSO
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*
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* Copyright IBM Corp. 2008
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* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License (version 2 only)
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* as published by the Free Software Foundation.
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*/
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#include <asm/vdso.h>
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#include <asm/asm-offsets.h>
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#include <asm/unistd.h>
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.text
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.align 4
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.globl __kernel_clock_gettime
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.type __kernel_clock_gettime,@function
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__kernel_clock_gettime:
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.cfi_startproc
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aghi %r15,-16
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larl %r5,_vdso_data
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cghi %r2,__CLOCK_REALTIME_COARSE
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je 4f
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cghi %r2,__CLOCK_REALTIME
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je 5f
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cghi %r2,-3 /* Per-thread CPUCLOCK with PID=0, VIRT=1 */
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je 9f
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cghi %r2,__CLOCK_MONOTONIC_COARSE
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je 3f
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cghi %r2,__CLOCK_MONOTONIC
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jne 12f
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/* CLOCK_MONOTONIC */
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0: lg %r4,__VDSO_UPD_COUNT(%r5) /* load update counter */
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tmll %r4,0x0001 /* pending update ? loop */
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jnz 0b
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stcke 0(%r15) /* Store TOD clock */
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lgf %r2,__VDSO_TK_SHIFT(%r5) /* Timekeeper shift */
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lg %r0,__VDSO_WTOM_SEC(%r5)
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lg %r1,1(%r15)
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sg %r1,__VDSO_XTIME_STAMP(%r5) /* TOD - cycle_last */
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msgf %r1,__VDSO_TK_MULT(%r5) /* * tk->mult */
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alg %r1,__VDSO_WTOM_NSEC(%r5)
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srlg %r1,%r1,0(%r2) /* >> tk->shift */
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clg %r4,__VDSO_UPD_COUNT(%r5) /* check update counter */
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jne 0b
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larl %r5,13f
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1: clg %r1,0(%r5)
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jl 2f
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slg %r1,0(%r5)
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aghi %r0,1
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j 1b
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2: stg %r0,0(%r3) /* store tp->tv_sec */
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stg %r1,8(%r3) /* store tp->tv_nsec */
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lghi %r2,0
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aghi %r15,16
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br %r14
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/* CLOCK_MONOTONIC_COARSE */
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3: lg %r4,__VDSO_UPD_COUNT(%r5) /* load update counter */
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tmll %r4,0x0001 /* pending update ? loop */
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jnz 3b
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lg %r0,__VDSO_WTOM_CRS_SEC(%r5)
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lg %r1,__VDSO_WTOM_CRS_NSEC(%r5)
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clg %r4,__VDSO_UPD_COUNT(%r5) /* check update counter */
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jne 3b
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j 2b
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/* CLOCK_REALTIME_COARSE */
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4: lg %r4,__VDSO_UPD_COUNT(%r5) /* load update counter */
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tmll %r4,0x0001 /* pending update ? loop */
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jnz 4b
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lg %r0,__VDSO_XTIME_CRS_SEC(%r5)
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lg %r1,__VDSO_XTIME_CRS_NSEC(%r5)
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clg %r4,__VDSO_UPD_COUNT(%r5) /* check update counter */
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jne 4b
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j 7f
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/* CLOCK_REALTIME */
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5: lg %r4,__VDSO_UPD_COUNT(%r5) /* load update counter */
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tmll %r4,0x0001 /* pending update ? loop */
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jnz 5b
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stcke 0(%r15) /* Store TOD clock */
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lg %r1,1(%r15)
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lg %r0,__VDSO_TS_END(%r5) /* TOD steering end time */
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slgr %r0,%r1 /* now - ts_steering_end */
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ltgr %r0,%r0 /* past end of steering ? */
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jm 17f
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srlg %r0,%r0,15 /* 1 per 2^16 */
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tm __VDSO_TS_DIR+3(%r5),0x01 /* steering direction? */
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jz 18f
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lcgr %r0,%r0 /* negative TOD offset */
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18: algr %r1,%r0 /* add steering offset */
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17: lgf %r2,__VDSO_TK_SHIFT(%r5) /* Timekeeper shift */
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sg %r1,__VDSO_XTIME_STAMP(%r5) /* TOD - cycle_last */
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msgf %r1,__VDSO_TK_MULT(%r5) /* * tk->mult */
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alg %r1,__VDSO_XTIME_NSEC(%r5) /* + tk->xtime_nsec */
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srlg %r1,%r1,0(%r2) /* >> tk->shift */
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lg %r0,__VDSO_XTIME_SEC(%r5) /* tk->xtime_sec */
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clg %r4,__VDSO_UPD_COUNT(%r5) /* check update counter */
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jne 5b
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larl %r5,13f
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6: clg %r1,0(%r5)
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jl 7f
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slg %r1,0(%r5)
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aghi %r0,1
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j 6b
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7: stg %r0,0(%r3) /* store tp->tv_sec */
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stg %r1,8(%r3) /* store tp->tv_nsec */
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lghi %r2,0
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aghi %r15,16
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br %r14
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/* CPUCLOCK_VIRT for this thread */
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9: icm %r0,15,__VDSO_ECTG_OK(%r5)
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jz 12f
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ear %r2,%a4
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llilh %r4,0x0100
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sar %a4,%r4
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lghi %r4,0
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epsw %r5,0
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sacf 512 /* Magic ectg instruction */
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.insn ssf,0xc80100000000,__VDSO_ECTG_BASE(4),__VDSO_ECTG_USER(4),4
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tml %r5,0x4000
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jo 11f
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tml %r5,0x8000
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jno 10f
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sacf 256
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j 11f
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10: sacf 0
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11: sar %a4,%r2
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algr %r1,%r0 /* r1 = cputime as TOD value */
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mghi %r1,1000 /* convert to nanoseconds */
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srlg %r1,%r1,12 /* r1 = cputime in nanosec */
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lgr %r4,%r1
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larl %r5,13f
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srlg %r1,%r1,9 /* divide by 1000000000 */
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mlg %r0,8(%r5)
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srlg %r0,%r0,11 /* r0 = tv_sec */
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stg %r0,0(%r3)
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msg %r0,0(%r5) /* calculate tv_nsec */
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slgr %r4,%r0 /* r4 = tv_nsec */
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stg %r4,8(%r3)
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lghi %r2,0
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aghi %r15,16
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br %r14
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/* Fallback to system call */
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12: lghi %r1,__NR_clock_gettime
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svc 0
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aghi %r15,16
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br %r14
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13: .quad 1000000000
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14: .quad 19342813113834067
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.cfi_endproc
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.size __kernel_clock_gettime,.-__kernel_clock_gettime
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