initfini.c 4.6 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150
  1. /* Special .init and .fini section support.
  2. Copyright (C) 1995, 1996, 1997, 2000 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. The GNU C Library is distributed in the hope that it will be useful,
  17. but WITHOUT ANY WARRANTY; without even the implied warranty of
  18. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  19. Lesser General Public License for more details.
  20. You should have received a copy of the GNU Lesser General Public
  21. License along with the GNU C Library; if not, write to the Free
  22. Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  23. 02111-1307 USA. */
  24. /* This file is compiled into assembly code which is then munged by a sed
  25. script into two files: crti.s and crtn.s.
  26. * crti.s puts a function prologue at the beginning of the
  27. .init and .fini sections and defines global symbols for
  28. those addresses, so they can be called as functions.
  29. * crtn.s puts the corresponding function epilogues
  30. in the .init and .fini sections. */
  31. #include <features.h>
  32. #undef GMON_SUPPORT
  33. /* We use embedded asm for .section unconditionally, as this makes it
  34. easier to insert the necessary directives into crtn.S. */
  35. #define SECTION(x) asm (".section " x );
  36. /* Declare symbols as hidden. Hidden symbols are only seen by
  37. * the link editor and not by the dynamic loader. */
  38. #ifdef HAVE_DOT_HIDDEN
  39. # define HIDDEN(func) asm (".hidden " #func );
  40. #else
  41. # define HIDDEN(func)
  42. #endif
  43. /* The initial common code ends here. */
  44. asm ("\n/*@HEADER_ENDS*/");
  45. /* To determine whether we need .end and .align: */
  46. //asm ("\n/*@TESTS_BEGIN*/");
  47. extern void dummy (void (*foo) (void));
  48. void
  49. dummy (void (*foo) (void))
  50. {
  51. if (foo)
  52. (*foo) ();
  53. }
  54. //asm ("\n/*@TESTS_END*/");
  55. /* The beginning of _init: */
  56. asm ("\n/*@_init_PROLOG_BEGINS*/");
  57. #ifdef GMON_SUPPORT
  58. static void
  59. call_gmon_start(void)
  60. {
  61. extern void __gmon_start__ (void) __attribute__ ((weak)); /*weak_extern (__gmon_start__);*/
  62. void (*gmon_start) (void) = __gmon_start__;
  63. if (gmon_start)
  64. gmon_start ();
  65. }
  66. #endif
  67. SECTION (".init")
  68. HIDDEN(_init)
  69. extern void i_am_not_a_leaf (void);
  70. extern void _init (void);
  71. void _init (void)
  72. {
  73. #ifdef GMON_SUPPORT
  74. /* We cannot use the normal constructor mechanism in gcrt1.o because it
  75. appears before crtbegin.o in the link, so the header elt of .ctors
  76. would come after the elt for __gmon_start__. One approach is for
  77. gcrt1.o to reference a symbol which would be defined by some library
  78. module which has a constructor; but then user code's constructors
  79. would come first, and not be profiled. */
  80. call_gmon_start ();
  81. #else
  82. asm ("\n/*@_init_PROLOG_PAUSES*/");
  83. {
  84. /* Let GCC know that _init is not a leaf function by having a dummy
  85. * function call here. We arrange for this call to be omitted from
  86. * either crt file. */
  87. i_am_not_a_leaf ();
  88. }
  89. asm ("\n/*@_init_PROLOG_UNPAUSES*/");
  90. #endif
  91. asm ("ALIGN");
  92. asm("END_INIT");
  93. /* Now the epilog. */
  94. asm ("\n/*@_init_PROLOG_ENDS*/");
  95. asm ("\n/*@_init_EPILOG_BEGINS*/");
  96. }
  97. /* End of the _init epilog, beginning of the _fini prolog. */
  98. asm ("\n/*@_init_EPILOG_ENDS*/");
  99. asm ("\n/*@_fini_PROLOG_BEGINS*/");
  100. SECTION (".fini")
  101. HIDDEN(_fini)
  102. extern void i_am_not_a_leaf2 (void);
  103. extern void _fini (void);
  104. void _fini (void)
  105. {
  106. /* End of the _fini prolog. */
  107. asm ("ALIGN");
  108. asm ("END_FINI");
  109. asm ("\n/*@_fini_PROLOG_ENDS*/");
  110. {
  111. /* Let GCC know that _fini is not a leaf function by having a dummy
  112. function call here. We arrange for this call to be omitted from
  113. either crt file. */
  114. i_am_not_a_leaf2 ();
  115. }
  116. /* Beginning of the _fini epilog. */
  117. asm ("\n/*@_fini_EPILOG_BEGINS*/");
  118. }
  119. /* End of the _fini epilog. Any further generated assembly (e.g. .ident)
  120. is shared between both crt files. */
  121. asm ("\n/*@_fini_EPILOG_ENDS*/");
  122. asm ("\n/*@TRAILER_BEGINS*/");
  123. /* End of file. */