sysdeps/alpha/elf/initfini.c

   1 /* Special .init and .fini section support for Alpha.
   2    Copyright (C) 2001, 2002, 2003 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    In addition to the permissions in the GNU Lesser General Public
  11    License, the Free Software Foundation gives you unlimited
  12    permission to link the compiled version of this file with other
  13    programs, and to distribute those programs without any restriction
  14    coming from the use of this file. (The GNU Lesser General Public
  15    License restrictions do apply in other respects; for example, they
  16    cover modification of the file, and distribution when not linked
  17    into another program.)
  18
  19    Note that people who make modified versions of this file are not
  20    obligated to grant this special exception for their modified
  21    versions; it is their choice whether to do so. The GNU Lesser
  22    General Public License gives permission to release a modified
  23    version without this exception; this exception also makes it
  24    possible to release a modified version which carries forward this
  25    exception.
  26
  27    The GNU C Library is distributed in the hope that it will be useful,
  28    but WITHOUT ANY WARRANTY; without even the implied warranty of
  29    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  30    Lesser General Public License for more details.
  31
  32    You should have received a copy of the GNU Lesser General Public
  33    License along with the GNU C Library; if not, write to the Free
  34    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  35    02111-1307 USA.  */
  36
  37 /* This file is compiled into assembly code which is then munged by a sed
  38    script into two files: crti.s and crtn.s.
  39
  40    * crti.s puts a function prologue at the beginning of the .init and .fini
  41    sections and defines global symbols for those addresses, so they can be
  42    called as functions.
  43
  44    * crtn.s puts the corresponding function epilogues in the .init and .fini
  45    sections.
  46
  47    This differs from what would be generated by the generic code in that
  48    we save and restore the GP within the function.  In order for linker
  49    relaxation to work, the value in the GP register on exit from a function
  50    must be valid for the function entry point.  Normally, a function is
  51    contained within one object file and this is not an issue, provided
  52    that the function reloads the gp after making any function calls.
  53    However, _init and _fini are constructed from pieces of many object
  54    files, all of which may have different GP values.  So we must reload
  55    the GP value from crti.o in crtn.o.  */
  56
  57 __asm__ ("                                              \n\
  58 #include \"defs.h\"                                     \n\
  59                                                         \n\
  60 /*@HEADER_ENDS*/                                        \n\
  61                                                         \n\
  62 /*@_init_PROLOG_BEGINS*/                                \n\
  63         .section .init, \"ax\", @progbits               \n\
  64         .globl  _init                                   \n\
  65         .type   _init, @function                        \n\
  66         .usepv  _init, std                              \n\
  67 _init:                                                  \n\
  68         ldgp    $29, 0($27)                             \n\
  69         subq    $30, 16, $30                            \n\
  70         lda     $27, __gmon_start__                     \n\
  71         stq     $26, 0($30)                             \n\
  72         stq     $29, 8($30)                             \n\
  73         beq     $27, 1f                                 \n\
  74         jsr     $26, ($27), __gmon_start__              \n\
  75         ldq     $29, 8($30)                             \n\
  76         .align 3                                        \n\
  77 1:                                                      \n\
  78 /*@_init_PROLOG_ENDS*/                                  \n\
  79                                                         \n\
  80 /*@_init_EPILOG_BEGINS*/                                \n\
  81         .section .init, \"ax\", @progbits               \n\
  82         ldq     $26, 0($30)                             \n\
  83         ldq     $29, 8($30)                             \n\
  84         addq    $30, 16, $30                            \n\
  85         ret                                             \n\
  86 /*@_init_EPILOG_ENDS*/                                  \n\
  87                                                         \n\
  88 /*@_fini_PROLOG_BEGINS*/                                \n\
  89         .section .fini, \"ax\", @progbits               \n\
  90         .globl  _fini                                   \n\
  91         .type   _fini,@function                         \n\
  92         .usepv  _fini,std                               \n\
  93 _fini:                                                  \n\
  94         ldgp    $29, 0($27)                             \n\
  95         subq    $30, 16, $30                            \n\
  96         stq     $26, 0($30)                             \n\
  97         stq     $29, 8($30)                             \n\
  98         .align 3                                        \n\
  99 /*@_fini_PROLOG_ENDS*/                                  \n\
 100                                                         \n\
 101 /*@_fini_EPILOG_BEGINS*/                                \n\
 102         .section .fini, \"ax\", @progbits               \n\
 103         ldq     $26, 0($30)                             \n\
 104         ldq     $29, 8($30)                             \n\
 105         addq    $30, 16, $30                            \n\
 106         ret                                             \n\
 107 /*@_fini_EPILOG_ENDS*/                                  \n\
 108                                                         \n\
 109 /*@TRAILER_BEGINS*/                                     \n\
 110 ");