/arch/ppc64/kernel/vdso64/gettimeofday.S

https://bitbucket.org/evzijst/gittest · Assembly · 91 lines · 56 code · 8 blank · 27 comment · 0 complexity · 6200aa918e9ecda3cdddb4301d6e35c2 MD5 · raw file 

    

  1. /*
    2. 

  2.  * Userland implementation of gettimeofday() for 64 bits processes in a
    3. 

  3.  * ppc64 kernel for use in the vDSO
    4. 

  4.  *
    5. 

  5.  * Copyright (C) 2004 Benjamin Herrenschmuidt (benh@kernel.crashing.org),
    6. 

  6.  *                    IBM Corp.
    7. 

  7.  *
    8. 

  8.  * This program is free software; you can redistribute it and/or
    9. 

  9.  * modify it under the terms of the GNU General Public License
    10. 

  10.  * as published by the Free Software Foundation; either version
    11. 

  11.  * 2 of the License, or (at your option) any later version.
    12. 

  12.  */
    13. 

  13. #include <linux/config.h>
    14. 

  14. #include <asm/processor.h>
    15. 

  15. #include <asm/ppc_asm.h>
    16. 

  16. #include <asm/vdso.h>
    17. 

  17. #include <asm/offsets.h>
    18. 

  18. 

  19. 	.text
    20. 

  20. /*
    21. 

  21.  * Exact prototype of gettimeofday
    22. 

  22.  *
    23. 

  23.  * int __kernel_gettimeofday(struct timeval *tv, struct timezone *tz);
    24. 

  24.  *
    25. 

  25.  */
    26. 

  26. V_FUNCTION_BEGIN(__kernel_gettimeofday)
    27. 

  27.   .cfi_startproc
    28. 

  28. 	mflr	r12
    29. 

  29.   .cfi_register lr,r12
    30. 

  30. 

  31. 	mr	r11,r3			/* r11 holds tv */
    32. 

  32. 	mr	r10,r4			/* r10 holds tz */
    33. 

  33. 	bl	V_LOCAL_FUNC(__get_datapage)		/* get data page */
    34. 

  34. 	bl	V_LOCAL_FUNC(__do_get_xsec)		/* get xsec from tb & kernel */
    35. 

  35. 	lis     r7,15			/* r7 = 1000000 = USEC_PER_SEC */
    36. 

  36. 	ori     r7,r7,16960
    37. 

  37. 	rldicl  r5,r4,44,20		/* r5 = sec = xsec / XSEC_PER_SEC */
    38. 

  38. 	rldicr  r6,r5,20,43		/* r6 = sec * XSEC_PER_SEC */
    39. 

  39. 	std	r5,TVAL64_TV_SEC(r11)	/* store sec in tv */
    40. 

  40. 	subf	r0,r6,r4		/* r0 = xsec = (xsec - r6) */
    41. 

  41. 	mulld   r0,r0,r7		/* usec = (xsec * USEC_PER_SEC) / XSEC_PER_SEC */
    42. 

  42. 	rldicl  r0,r0,44,20
    43. 

  43. 	cmpldi	cr0,r10,0		/* check if tz is NULL */
    44. 

  44. 	std	r0,TVAL64_TV_USEC(r11)	/* store usec in tv */
    45. 

  45. 	beq	1f
    46. 

  46. 	lwz	r4,CFG_TZ_MINUTEWEST(r3)/* fill tz */
    47. 

  47. 	lwz	r5,CFG_TZ_DSTTIME(r3)
    48. 

  48. 	stw	r4,TZONE_TZ_MINWEST(r10)
    49. 

  49. 	stw	r5,TZONE_TZ_DSTTIME(r10)
    50. 

  50. 1:	mtlr	r12
    51. 

  51. 	li	r3,0			/* always success */
    52. 

  52. 	blr
    53. 

  53.   .cfi_endproc
    54. 

  54. V_FUNCTION_END(__kernel_gettimeofday)
    55. 

  55. 

  56. 

  57. /*
    58. 

  58.  * This is the core of gettimeofday(), it returns the xsec
    59. 

  59.  * value in r4 and expects the datapage ptr (non clobbered)
    60. 

  60.  * in r3. clobbers r0,r4,r5,r6,r7,r8
    61. 

  61. */
    62. 

  62. V_FUNCTION_BEGIN(__do_get_xsec)
    63. 

  63.   .cfi_startproc
    64. 

  64. 	/* check for update count & load values */
    65. 

  65. 1:	ld	r7,CFG_TB_UPDATE_COUNT(r3)
    66. 

  66. 	andi.	r0,r4,1			/* pending update ? loop */
    67. 

  67. 	bne-	1b
    68. 

  68. 	xor	r0,r4,r4		/* create dependency */
    69. 

  69. 	add	r3,r3,r0
    70. 

  70. 

  71. 	/* Get TB & offset it */
    72. 

  72. 	mftb	r8
    73. 

  73. 	ld	r9,CFG_TB_ORIG_STAMP(r3)
    74. 

  74. 	subf	r8,r9,r8
    75. 

  75. 

  76. 	/* Scale result */
    77. 

  77. 	ld	r5,CFG_TB_TO_XS(r3)
    78. 

  78. 	mulhdu	r8,r8,r5
    79. 

  79. 

  80. 	/* Add stamp since epoch */
    81. 

  81. 	ld	r6,CFG_STAMP_XSEC(r3)
    82. 

  82. 	add	r4,r6,r8
    83. 

  83. 

  84. 	xor	r0,r4,r4
    85. 

  85. 	add	r3,r3,r0
    86. 

  86. 	ld	r0,CFG_TB_UPDATE_COUNT(r3)
    87. 

  87.         cmpld   cr0,r0,r7		/* check if updated */
    88. 

  88. 	bne-	1b
    89. 

  89. 	blr
    90. 

  90.   .cfi_endproc
    91. 

  91. V_FUNCTION_END(__do_get_xsec)
    92.