crt1.S 4.5 KB

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  1. /* Startup code compliant to the ELF m68k ABI.
  2. Copyright (C) 1996, 1997, 1998, 2001, 2002 Free Software Foundation, Inc.
  3. This file is part of the GNU C Library.
  4. The GNU C Library is free software; you can redistribute it and/or
  5. modify it under the terms of the GNU Lesser General Public
  6. License as published by the Free Software Foundation; either
  7. version 2.1 of the License, or (at your option) any later version.
  8. In addition to the permissions in the GNU Lesser General Public
  9. License, the Free Software Foundation gives you unlimited
  10. permission to link the compiled version of this file with other
  11. programs, and to distribute those programs without any restriction
  12. coming from the use of this file. (The GNU Lesser General Public
  13. License restrictions do apply in other respects; for example, they
  14. cover modification of the file, and distribution when not linked
  15. into another program.)
  16. Note that people who make modified versions of this file are not
  17. obligated to grant this special exception for their modified
  18. versions; it is their choice whether to do so. The GNU Lesser
  19. General Public License gives permission to release a modified
  20. version without this exception; this exception also makes it
  21. possible to release a modified version which carries forward this
  22. exception.
  23. The GNU C Library is distributed in the hope that it will be useful,
  24. but WITHOUT ANY WARRANTY; without even the implied warranty of
  25. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  26. Lesser General Public License for more details.
  27. You should have received a copy of the GNU Lesser General Public
  28. License along with the GNU C Library; if not, see
  29. <http://www.gnu.org/licenses/>. */
  30. #include <features.h>
  31. #include "m68k_pic.S"
  32. #ifndef L_Scrt1
  33. /* This is the canonical entry point, usually the first thing in the text
  34. segment. The SVR4/m68k ABI says that when the entry point runs,
  35. most registers' values are unspecified, except for:
  36. %a1 Contains a function pointer to be registered with `atexit'.
  37. This is how the dynamic linker arranges to have DT_FINI
  38. functions called for shared libraries that have been loaded
  39. before this code runs.
  40. %sp The stack contains the arguments and environment:
  41. 0(%sp) argc
  42. 4(%sp) argv[0]
  43. ...
  44. (4*argc)(%sp) NULL
  45. (4*(argc+1))(%sp) envp[0]
  46. ...
  47. NULL
  48. The uclinux conventions are different. %a1 is not defined on entry
  49. and the stack is laid out as follows:
  50. 0(%sp) argc
  51. 4(%sp) argv
  52. 8(%sp) envp
  53. */
  54. .text
  55. .type _init,%function
  56. .type _fini,%function
  57. #ifndef __UCLIBC_CTOR_DTOR__
  58. .weak _init
  59. .weak _fini
  60. #endif
  61. .globl _start
  62. .type _start,@function
  63. _start:
  64. /* Clear the frame pointer. The ABI suggests this be done, to mark
  65. the outermost frame obviously. */
  66. sub.l %fp, %fp
  67. #if !defined __ARCH_USE_MMU__ && defined __PIC__
  68. /* Set up the global pointer. The GOT is at the beginning of the
  69. data segment, whose address is in %d5. */
  70. move.l %d5,%a5
  71. .equ have_current_got, 1
  72. #endif
  73. #ifdef __UCLIBC_FORMAT_SHARED_FLAT__
  74. CALL __shared_flat_add_library,%a1
  75. #endif
  76. /* Extract the arguments as encoded on the stack and set up the
  77. arguments for `main': argc, argv. envp will be determined
  78. later in __libc_start_main. */
  79. move.l (%sp)+, %d0 /* Pop the argument count. */
  80. #ifndef __ARCH_USE_MMU__
  81. move.l (%sp)+, %a0
  82. #else
  83. move.l %sp, %a0 /* The argument vector starts just at the
  84. current stack top. */
  85. #endif
  86. /* Provide the highest stack address to the user code (for stacks
  87. which grow downward). */
  88. pea (%sp)
  89. #ifndef __ARCH_USE_MMU__
  90. clr.l -(%sp)
  91. #else
  92. pea (%a1) /* Push address of the shared library
  93. termination function. */
  94. #endif
  95. /* Push the address of our own entry points to `.fini' and
  96. `.init'. */
  97. #if defined __UCLIBC_FORMAT_SHARED_FLAT__
  98. PEA_TEXT __shared_flat_fini,%a1
  99. PEA_TEXT __shared_flat_init,%a1
  100. #else
  101. PEA_TEXT _fini,%a1
  102. PEA_TEXT _init,%a1
  103. #endif
  104. pea (%a0) /* Push second argument: argv. */
  105. move.l %d0, -(%sp) /* Push first argument: argc. */
  106. PEA_TEXT main,%a1
  107. /* Call the user's main function, and exit with its value. But
  108. let the libc call main. */
  109. CALL __uClibc_main,%a1
  110. illegal /* Crash if somehow `exit' does return. */
  111. #else
  112. .text
  113. .globl lib_main
  114. .hidden lib_main
  115. .type lib_main,@function
  116. lib_main:
  117. move.l %d5,%a5
  118. JUMP __shared_flat_add_library,%a0
  119. .hidden _current_shared_library_a5_offset_
  120. #endif
  121. /* Define a symbol for the first piece of initialized data. */
  122. .data
  123. .globl __data_start
  124. __data_start:
  125. .long 0
  126. .weak data_start
  127. data_start = __data_start