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

crt0.S 1.9 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. 	.globl	_zimage_start_lib
    23. 

  23. _zimage_start_lib:
    24. 

  24. 	/* Work out the offset between the address we were linked at
    25. 

  25. 	   and the address where we're running. */
    26. 

  26. 	bl	1f
    27. 

  27. 1:	mflr	r0
    28. 

  28. 	lis	r9,1b@ha
    29. 

  29. 	addi	r9,r9,1b@l
    30. 

  30. 	subf.	r0,r9,r0
    31. 

  31. 	beq	3f		/* if running at same address as linked */
    32. 

  32. 

  33. 	/* The .got2 section contains a list of addresses, so add
    34. 

  34. 	   the address offset onto each entry. */
    35. 

  35. 	lis	r9,__got2_start@ha
    36. 

  36. 	addi	r9,r9,__got2_start@l
    37. 

  37. 	lis	r8,__got2_end@ha
    38. 

  38. 	addi	r8,r8,__got2_end@l
    39. 

  39. 	subf.	r8,r9,r8
    40. 

  40. 	beq	3f
    41. 

  41. 	srwi.	r8,r8,2
    42. 

  42. 	mtctr	r8
    43. 

  43. 	add	r9,r0,r9
    44. 

  44. 2:	lwz	r8,0(r9)
    45. 

  45. 	add	r8,r8,r0
    46. 

  46. 	stw	r8,0(r9)
    47. 

  47. 	addi	r9,r9,4
    48. 

  48. 	bdnz	2b
    49. 

  49. 

  50. 	/* Do a cache flush for our text, in case the loader didn't */
    51. 

  51. 3:	lis	r9,_start@ha
    52. 

  52. 	addi	r9,r9,_start@l
    53. 

  53. 	add	r9,r0,r9
    54. 

  54. 	lis	r8,_etext@ha
    55. 

  55. 	addi	r8,r8,_etext@l
    56. 

  56. 	add	r8,r0,r8
    57. 

  57. 4:	dcbf	r0,r9
    58. 

  58. 	icbi	r0,r9
    59. 

  59. 	addi	r9,r9,0x20
    60. 

  60. 	cmplw	cr0,r9,r8
    61. 

  61. 	blt	4b
    62. 

  62. 	sync
    63. 

  63. 	isync
    64. 

  64. 

  65. 	/* Clear the BSS */
    66. 

  66. 	lis	r9,__bss_start@ha
    67. 

  67. 	addi	r9,r9,__bss_start@l
    68. 

  68. 	add	r9,r0,r9
    69. 

  69. 	lis	r8,_end@ha
    70. 

  70. 	addi	r8,r8,_end@l
    71. 

  71. 	add	r8,r0,r8
    72. 

  72. 	li	r10,0
    73. 

  73. 5:	stw	r10,0(r9)
    74. 

  74. 	addi	r9,r9,4
    75. 

  75. 	cmplw	cr0,r9,r8
    76. 

  76. 	blt	5b
    77. 

  77. 

  78. 	/* Possibly set up a custom stack */
    79. 

  79. .weak	_platform_stack_top
    80. 

  80. 	lis	r8,_platform_stack_top@ha
    81. 

  81. 	addi	r8,r8,_platform_stack_top@l
    82. 

  82. 	cmpwi	r8,0
    83. 

  83. 	beq	6f
    84. 

  84. 	add	r8,r0,r8
    85. 

  85. 	lwz	r1,0(r8)
    86. 

  86. 	add	r1,r0,r1
    87. 

  87. 	li	r0,0
    88. 

  88. 	stwu	r0,-16(r1)	/* establish a stack frame */
    89. 

  89. 6:
    90. 

  90. 

  91. 	/* Call platform_init() */
    92. 

  92. 	bl	platform_init
    93. 

  93. 

  94. 	/* Call start */
    95. 

  95. 	b	start
    96.