root/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 #include <asm/dwarf.h>
  13 #include <asm/ptrace.h>
  14 
  15         .text
  16         .align 4
  17         .globl __kernel_gettimeofday
  18         .type  __kernel_gettimeofday,@function
  19 __kernel_gettimeofday:
  20         CFI_STARTPROC
  21         aghi    %r15,-16
  22         CFI_ADJUST_CFA_OFFSET 16
  23         CFI_VAL_OFFSET 15, -STACK_FRAME_OVERHEAD
  24         larl    %r5,_vdso_data
  25 0:      ltgr    %r3,%r3                         /* check if tz is NULL */
  26         je      1f
  27         mvc     0(8,%r3),__VDSO_TIMEZONE(%r5)
  28 1:      ltgr    %r2,%r2                         /* check if tv is NULL */
  29         je      4f
  30         lg      %r4,__VDSO_UPD_COUNT(%r5)       /* load update counter */
  31         tmll    %r4,0x0001                      /* pending update ? loop */
  32         jnz     0b
  33         stcke   0(%r15)                         /* Store TOD clock */
  34         lg      %r1,1(%r15)
  35         lg      %r0,__VDSO_TS_END(%r5)          /* TOD steering end time */
  36         slgr    %r0,%r1                         /* now - ts_steering_end */
  37         ltgr    %r0,%r0                         /* past end of steering ? */
  38         jm      6f
  39         srlg    %r0,%r0,15                      /* 1 per 2^16 */
  40         tm      __VDSO_TS_DIR+3(%r5),0x01       /* steering direction? */
  41         jz      7f
  42         lcgr    %r0,%r0                         /* negative TOD offset */
  43 7:      algr    %r1,%r0                         /* add steering offset */
  44 6:      sg      %r1,__VDSO_XTIME_STAMP(%r5)     /* TOD - cycle_last */
  45         msgf    %r1,__VDSO_TK_MULT(%r5)         /*  * tk->mult */
  46         alg     %r1,__VDSO_XTIME_NSEC(%r5)      /*  + tk->xtime_nsec */
  47         lg      %r0,__VDSO_XTIME_SEC(%r5)       /* tk->xtime_sec */
  48         clg     %r4,__VDSO_UPD_COUNT(%r5)       /* check update counter */
  49         jne     0b
  50         lgf     %r5,__VDSO_TK_SHIFT(%r5)        /* Timekeeper shift */
  51         srlg    %r1,%r1,0(%r5)                  /*  >> tk->shift */
  52         larl    %r5,5f
  53 2:      clg     %r1,0(%r5)
  54         jl      3f
  55         slg     %r1,0(%r5)
  56         aghi    %r0,1
  57         j       2b
  58 3:      stg     %r0,0(%r2)                      /* store tv->tv_sec */
  59         slgr    %r0,%r0                         /* tv_nsec -> tv_usec */
  60         ml      %r0,8(%r5)
  61         srlg    %r0,%r0,6
  62         stg     %r0,8(%r2)                      /* store tv->tv_usec */
  63 4:      lghi    %r2,0
  64         aghi    %r15,16
  65         CFI_ADJUST_CFA_OFFSET -16
  66         CFI_RESTORE 15
  67         br      %r14
  68         CFI_ENDPROC
  69 5:      .quad   1000000000
  70         .long   274877907
  71         .size   __kernel_gettimeofday,.-__kernel_gettimeofday