libgcc/config/arm/crtn.S

   1 #   Copyright (C) 2001, 2004, 2008, 2009, 2010, 2011
   2 #   Free Software Foundation, Inc.
   3 #   Written By Nick Clifton
   4 #
   5 # This file is free software; you can redistribute it and/or modify it
   6 # under the terms of the GNU General Public License as published by the
   7 # Free Software Foundation; either version 3, or (at your option) any
   8 # later version.
   9 #
  10 # This file is distributed in the hope that it will be useful, but
  11 # WITHOUT ANY WARRANTY; without even the implied warranty of
  12 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13 # General Public License for more details.
  14 #
  15 # Under Section 7 of GPL version 3, you are granted additional
  16 # permissions described in the GCC Runtime Library Exception, version
  17 # 3.1, as published by the Free Software Foundation.
  18 #
  19 # You should have received a copy of the GNU General Public License and
  20 # a copy of the GCC Runtime Library Exception along with this program;
  21 # see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  22 # <http://www.gnu.org/licenses/>.
  23
  24 /* An executable stack is *not* required for these functions.  */
  25 #if defined(__ELF__) && defined(__linux__)
  26 .section .note.GNU-stack,"",%progbits
  27 .previous
  28 #endif
  29
  30 #ifdef __ARM_EABI__
  31 /* Some attributes that are common to all routines in this file.  */
  32         /* Tag_ABI_align_needed: This code does not require 8-byte
  33            alignment from the caller.  */
  34         /* .eabi_attribute 24, 0  -- default setting.  */
  35         /* Tag_ABI_align_preserved: This code preserves 8-byte
  36            alignment in any callee.  */
  37         .eabi_attribute 25, 1
  38 #endif /* __ARM_EABI__ */
  39
  40 # This file just makes sure that the .fini and .init sections do in
  41 # fact return.  Users may put any desired instructions in those sections.
  42 # This file is the last thing linked into any executable.
  43
  44         # Note - this macro is complemented by the FUNC_START macro
  45         # in crti.S.  If you change this macro you must also change
  46         # that macro match.
  47         #
  48         # Note - we do not try any fancy optimizations of the return
  49         # sequences here, it is just not worth it.  Instead keep things
  50         # simple.  Restore all the save resgisters, including the link
  51         # register and then perform the correct function return instruction.
  52         # We also save/restore r3 to ensure stack alignment.
  53 .macro FUNC_END
  54 #ifdef __thumb__
  55         .thumb
  56
  57         pop     {r3, r4, r5, r6, r7}
  58         pop     {r3}
  59         mov     lr, r3
  60 #else
  61         .arm
  62
  63         sub     sp, fp, #40
  64         ldmfd   sp, {r4, r5, r6, r7, r8, r9, sl, fp, sp, lr}
  65 #endif
  66
  67 #if defined __THUMB_INTERWORK__ || defined __thumb__
  68         bx      lr
  69 #else
  70         mov     pc, lr
  71 #endif
  72 .endm
  73
  74
  75         .section        ".init"
  76         ;;
  77         FUNC_END
  78
  79         .section        ".fini"
  80         ;;
  81         FUNC_END
  82
  83 # end of crtn.S