arch/s390/kernel/vdso64/gettimeofday.S

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * Userland implementation of gettimeofday() for 64 bits processes in a
   4  * s390 kernel for use in the vDSO
   5  *
   6  *  Copyright IBM Corp. 2008
   7  *  Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
   8  */
   9 #include <asm/vdso.h>
  10 #include <asm/asm-offsets.h>
  11 #include <asm/unistd.h>
  12
  13         .text
  14         .align 4
  15         .globl __kernel_gettimeofday
  16         .type  __kernel_gettimeofday,@function
  17 __kernel_gettimeofday:
  18         .cfi_startproc
  19         aghi    %r15,-16
  20         larl    %r5,_vdso_data
  21 0:      ltgr    %r3,%r3                         /* check if tz is NULL */
  22         je      1f
  23         mvc     0(8,%r3),__VDSO_TIMEZONE(%r5)
  24 1:      ltgr    %r2,%r2                         /* check if tv is NULL */
  25         je      4f
  26         lg      %r4,__VDSO_UPD_COUNT(%r5)       /* load update counter */
  27         tmll    %r4,0x0001                      /* pending update ? loop */
  28         jnz     0b
  29         stcke   0(%r15)                         /* Store TOD clock */
  30         lg      %r1,1(%r15)
  31         lg      %r0,__VDSO_TS_END(%r5)          /* TOD steering end time */
  32         slgr    %r0,%r1                         /* now - ts_steering_end */
  33         ltgr    %r0,%r0                         /* past end of steering ? */
  34         jm      6f
  35         srlg    %r0,%r0,15                      /* 1 per 2^16 */
  36         tm      __VDSO_TS_DIR+3(%r5),0x01       /* steering direction? */
  37         jz      7f
  38         lcgr    %r0,%r0                         /* negative TOD offset */
  39 7:      algr    %r1,%r0                         /* add steering offset */
  40 6:      sg      %r1,__VDSO_XTIME_STAMP(%r5)     /* TOD - cycle_last */
  41         msgf    %r1,__VDSO_TK_MULT(%r5)         /*  * tk->mult */
  42         alg     %r1,__VDSO_XTIME_NSEC(%r5)      /*  + tk->xtime_nsec */
  43         lg      %r0,__VDSO_XTIME_SEC(%r5)       /* tk->xtime_sec */
  44         clg     %r4,__VDSO_UPD_COUNT(%r5)       /* check update counter */
  45         jne     0b
  46         lgf     %r5,__VDSO_TK_SHIFT(%r5)        /* Timekeeper shift */
  47         srlg    %r1,%r1,0(%r5)                  /*  >> tk->shift */
  48         larl    %r5,5f
  49 2:      clg     %r1,0(%r5)
  50         jl      3f
  51         slg     %r1,0(%r5)
  52         aghi    %r0,1
  53         j       2b
  54 3:      stg     %r0,0(%r2)                      /* store tv->tv_sec */
  55         slgr    %r0,%r0                         /* tv_nsec -> tv_usec */
  56         ml      %r0,8(%r5)
  57         srlg    %r0,%r0,6
  58         stg     %r0,8(%r2)                      /* store tv->tv_usec */
  59 4:      lghi    %r2,0
  60         aghi    %r15,16
  61         br      %r14
  62 5:      .quad   1000000000
  63         .long   274877907
  64         .cfi_endproc
  65         .size   __kernel_gettimeofday,.-__kernel_gettimeofday