sysdeps/aarch64/crti.S

   1 /* Special .init and .fini section support for AArch64.
   2    Copyright (C) 1995-2014 Free Software Foundation, Inc.
   3
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    In addition to the permissions in the GNU Lesser General Public
  12    License, the Free Software Foundation gives you unlimited
  13    permission to link the compiled version of this file with other
  14    programs, and to distribute those programs without any restriction
  15    coming from the use of this file. (The GNU Lesser General Public
  16    License restrictions do apply in other respects; for example, they
  17    cover modification of the file, and distribution when not linked
  18    into another program.)
  19
  20    Note that people who make modified versions of this file are not
  21    obligated to grant this special exception for their modified
  22    versions; it is their choice whether to do so. The GNU Lesser
  23    General Public License gives permission to release a modified
  24    version without this exception; this exception also makes it
  25    possible to release a modified version which carries forward this
  26    exception.
  27
  28    The GNU C Library is distributed in the hope that it will be useful,
  29    but WITHOUT ANY WARRANTY; without even the implied warranty of
  30    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  31    Lesser General Public License for more details.
  32
  33    You should have received a copy of the GNU Lesser General Public
  34    License along with the GNU C Library; if not, see
  35    <http://www.gnu.org/licenses/>.  */
  36
  37 /* crti.S puts a function prologue at the beginning of the .init and
  38    .fini sections and defines global symbols for those addresses, so
  39    they can be called as functions.  The symbols _init and _fini are
  40    magic and cause the linker to emit DT_INIT and DT_FINI.  */
  41
  42 #include <libc-symbols.h>
  43
  44 #ifndef PREINIT_FUNCTION
  45 # define PREINIT_FUNCTION __gmon_start__
  46 #endif
  47
  48 #ifndef PREINIT_FUNCTION_WEAK
  49 # define PREINIT_FUNCTION_WEAK 1
  50 #endif
  51
  52 #if PREINIT_FUNCTION_WEAK
  53         weak_extern (PREINIT_FUNCTION)
  54 #else
  55         .hidden PREINIT_FUNCTION
  56 #endif
  57
  58 #if PREINIT_FUNCTION_WEAK
  59         .align  2
  60         .type   call_weak_fn, %function
  61 call_weak_fn:
  62         adrp    x0, :got:PREINIT_FUNCTION
  63         ldr     x0, [x0, #:got_lo12:PREINIT_FUNCTION]
  64         cbz     x0, 1f
  65         b       PREINIT_FUNCTION
  66 1:
  67         RET
  68         .size   call_weak_fn, .-call_weak_fn
  69 #endif
  70
  71         .section .init,"ax",%progbits
  72         .align  2
  73         .global _init
  74         .type   _init, %function
  75 _init:
  76         stp     x29, x30, [sp, -16]!
  77         mov     x29, sp
  78 #if PREINIT_FUNCTION_WEAK
  79         bl      call_weak_fn
  80 #else
  81         bl      PREINIT_FUNCTION
  82 #endif
  83
  84         .section        .fini,"ax",%progbits
  85         .align  2
  86         .global _fini
  87         .type   _fini, %function
  88 _fini:
  89         stp     x29, x30, [sp, -16]!
  90         mov     x29, sp