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linux-vybrid_pu...
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arch
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powerpc
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boot
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crt0.S

crt0.S 1.8 KB
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  1. /*
    2. 

  2.  * Copyright (C) Paul Mackerras 1997.
    3. 

  3.  *
    4. 

  4.  * This program is free software; you can redistribute it and/or
    5. 

  5.  * modify it under the terms of the GNU General Public License
    6. 

  6.  * as published by the Free Software Foundation; either version
    7. 

  7.  * 2 of the License, or (at your option) any later version.
    8. 

  8.  *
    9. 

  9.  * NOTE: this code runs in 32 bit mode and is packaged as ELF32.
    10. 

  10.  */
    11. 

  11. 

  12. #include "ppc_asm.h"
    13. 

  13. 

  14. 	.text
    15. 

  15. 	/* a procedure descriptor used when booting this as a COFF file */
    16. 

  16. _zimage_start_opd:
    17. 

  17. 	.long	_zimage_start, 0, 0, 0
    18. 

  18. 

  19. 	.weak	_zimage_start
    20. 

  20. 	.globl	_zimage_start
    21. 

  21. _zimage_start:
    22. 

  22. 	/* Work out the offset between the address we were linked at
    23. 

  23. 	   and the address where we're running. */
    24. 

  24. 	bl	1f
    25. 

  25. 1:	mflr	r0
    26. 

  26. 	lis	r9,1b@ha
    27. 

  27. 	addi	r9,r9,1b@l
    28. 

  28. 	subf.	r0,r9,r0
    29. 

  29. 	beq	3f		/* if running at same address as linked */
    30. 

  30. 

  31. 	/* The .got2 section contains a list of addresses, so add
    32. 

  32. 	   the address offset onto each entry. */
    33. 

  33. 	lis	r9,__got2_start@ha
    34. 

  34. 	addi	r9,r9,__got2_start@l
    35. 

  35. 	lis	r8,__got2_end@ha
    36. 

  36. 	addi	r8,r8,__got2_end@l
    37. 

  37. 	subf.	r8,r9,r8
    38. 

  38. 	beq	3f
    39. 

  39. 	srwi.	r8,r8,2
    40. 

  40. 	mtctr	r8
    41. 

  41. 	add	r9,r0,r9
    42. 

  42. 2:	lwz	r8,0(r9)
    43. 

  43. 	add	r8,r8,r0
    44. 

  44. 	stw	r8,0(r9)
    45. 

  45. 	addi	r9,r9,4
    46. 

  46. 	bdnz	2b
    47. 

  47. 

  48. 	/* Do a cache flush for our text, in case the loader didn't */
    49. 

  49. 3:	lis	r9,_start@ha
    50. 

  50. 	addi	r9,r9,_start@l
    51. 

  51. 	add	r9,r0,r9
    52. 

  52. 	lis	r8,_etext@ha
    53. 

  53. 	addi	r8,r8,_etext@l
    54. 

  54. 	add	r8,r0,r8
    55. 

  55. 4:	dcbf	r0,r9
    56. 

  56. 	icbi	r0,r9
    57. 

  57. 	addi	r9,r9,0x20
    58. 

  58. 	cmplw	cr0,r9,r8
    59. 

  59. 	blt	4b
    60. 

  60. 	sync
    61. 

  61. 	isync
    62. 

  62. 

  63. 	/* Clear the BSS */
    64. 

  64. 	lis	r9,__bss_start@ha
    65. 

  65. 	addi	r9,r9,__bss_start@l
    66. 

  66. 	lis	r8,_end@ha
    67. 

  67. 	addi	r8,r8,_end@l
    68. 

  68. 	li	r0,0
    69. 

  69. 5:	stw	r0,0(r9)
    70. 

  70. 	addi	r9,r9,4
    71. 

  71. 	cmplw	cr0,r9,r8
    72. 

  72. 	blt	5b
    73. 

  73. 

  74. 	/* Possibly set up a custom stack */
    75. 

  75. .weak	_platform_stack_top
    76. 

  76. 	lis	r8,_platform_stack_top@ha
    77. 

  77. 	addi	r8,r8,_platform_stack_top@l
    78. 

  78. 	cmpwi	r8,0
    79. 

  79. 	beq	6f
    80. 

  80. 	lwz	r1,0(r8)
    81. 

  81. 	li	r0,0
    82. 

  82. 	stwu	r0,-16(r1)	/* establish a stack frame */
    83. 

  83. 6:
    84. 

  84. 

  85. 	/* Call platform_init() */
    86. 

  86. 	bl	platform_init
    87. 

  87. 

  88. 	/* Call start */
    89. 

  89. 	mr	r3,r1
    90. 

  90. 	b	start
    91.