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https://github.com/torvalds/linux
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c742b31c03
The extract cpu time instruction (ectg) instruction allows the user process to get the current thread cputime without calling into the kernel. The code that uses the instruction needs to switch to the access registers mode to get access to the per-cpu info page that contains the two base values that are needed to calculate the current cputime from the CPU timer with the ectg instruction. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
119 lines
3 KiB
ArmAsm
119 lines
3 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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larl %r5,_vdso_data
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cghi %r2,CLOCK_REALTIME
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je 4f
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cghi %r2,-2 /* CLOCK_THREAD_CPUTIME_ID for this thread */
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je 9f
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cghi %r2,CLOCK_MONOTONIC
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jne 12f
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/* CLOCK_MONOTONIC */
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ltgr %r3,%r3
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jz 3f /* tp == NULL */
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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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stck 48(%r15) /* Store TOD clock */
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lg %r1,48(%r15)
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sg %r1,__VDSO_XTIME_STAMP(%r5) /* TOD - cycle_last */
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mghi %r1,1000
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srlg %r1,%r1,12 /* cyc2ns(clock,cycle_delta) */
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alg %r1,__VDSO_XTIME_NSEC(%r5) /* + xtime */
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lg %r0,__VDSO_XTIME_SEC(%r5)
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alg %r1,__VDSO_WTOM_NSEC(%r5) /* + wall_to_monotonic */
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alg %r0,__VDSO_WTOM_SEC(%r5)
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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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3: lghi %r2,0
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br %r14
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/* CLOCK_REALTIME */
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4: ltr %r3,%r3 /* tp == NULL */
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jz 8f
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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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stck 48(%r15) /* Store TOD clock */
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lg %r1,48(%r15)
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sg %r1,__VDSO_XTIME_STAMP(%r5) /* TOD - cycle_last */
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mghi %r1,1000
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srlg %r1,%r1,12 /* cyc2ns(clock,cycle_delta) */
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alg %r1,__VDSO_XTIME_NSEC(%r5) /* + xtime */
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lg %r0,__VDSO_XTIME_SEC(%r5)
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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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8: lghi %r2,0
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br %r14
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/* CLOCK_THREAD_CPUTIME_ID 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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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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sacf 0
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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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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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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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