sysdeps/arc/start.S

   1 /* Startup code for ARC.
   2    Copyright (C) 2020 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    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library.  If not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #define __ASSEMBLY__ 1
  20 #include <entry.h>
  21 #include <sysdep.h>
  22
  23 #ifndef ENTRY_POINT
  24 # error ENTRY_POINT needs to be defined for ARC
  25 #endif
  26
  27 /* When we enter this piece of code, the program stack looks like this:
  28         argc            argument counter (integer)
  29         argv[0]         program name (pointer)
  30         argv[1...N]     program args (pointers)
  31         argv[argc-1]    end of args (integer)
  32         NULL
  33         env[0...N]      environment variables (pointers)
  34         NULL.  */
  35
  36 ENTRY (ENTRY_POINT)
  37
  38         /* Needed to make gdb backtraces stop here.  */
  39         .cfi_label .Ldummy
  40         cfi_undefined (blink)
  41
  42         mov     fp, 0
  43         ld_s    r1, [sp]        /* argc.  */
  44
  45         mov_s   r5, r0          /* rltd_fini.  */
  46         add_s   r2, sp, 4       /* argv.  */
  47         and     sp, sp, -8
  48         mov     r6, sp
  49
  50         /* __libc_start_main (main, argc, argv, init, fini, rtld_fini, stack_end).  */
  51
  52 #ifdef SHARED
  53         ld      r0, [pcl, @main@gotpc]
  54         ld      r3, [pcl, @__libc_csu_init@gotpc]
  55         ld      r4, [pcl, @__libc_csu_fini@gotpc]
  56         bl      __libc_start_main@plt
  57 #else
  58         mov_s   r0, main
  59         mov_s   r3, __libc_csu_init
  60         mov     r4, __libc_csu_fini
  61         bl      __libc_start_main
  62 #endif
  63
  64         /* Should never get here.  */
  65         flag    1
  66 END (ENTRY_POINT)
  67
  68 /* Define a symbol for the first piece of initialized data.  */
  69         .data
  70         .globl __data_start
  71 __data_start:
  72         .long 0
  73         .weak data_start
  74         data_start = __data_start