sysdeps/csky/abiv2/start.S

   1 /* Startup code compliant to the ELF C-SKY ABIV2.
   2    Copyright (C) 2018-2019 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, see
  34    <http://www.gnu.org/licenses/>.  */
  35
  36 /* We need to call:
  37    __libc_start_main (int (*main) (int, char **, char **), int argc,
  38                       char **argv, void (*init) (void), void (*fini) (void),
  39                       void (*rtld_fini) (void), void *stack_end)
  40  */
  41
  42 #include <sysdep.h>
  43
  44         .text
  45         .globl _start;
  46         .type _start,@function;
  47         .align 4;
  48 _start:
  49         cfi_startproc
  50         .cfi_label .Ldummy
  51         cfi_undefined (lr)
  52         subi    sp, 8
  53         /* Clear the link register since this is the outermost frame.  */
  54         movi    lr, 0
  55         /* Pop argc off the stack and save a pointer to argv.  */
  56         ldw     a1, (sp, 8)     /* Init argc for __libc_start_main.  */
  57         addi    a2, sp, 12      /* Init argv for __libc_start_main.  */
  58
  59         /* Push stack limit.  */
  60         stw     a2, (sp, 8)
  61         /* Push rtld_fini.  */
  62         stw     a0, (sp, 4)
  63
  64 #ifdef SHARED
  65         grs     t0, .Lgetpc
  66 .Lgetpc:
  67         lrw     gb, .Lgetpc@GOTPC
  68         addu    gb, t0
  69         lrw     a3, __libc_csu_fini@GOT
  70         ldr.w   a3, (gb, a3 << 0)
  71         stw     a3, (sp, 0)
  72
  73         lrw     a3, __libc_csu_init@GOT
  74         addu    a3, gb
  75         ldw     a3, (a3, 0)
  76
  77         lrw     t0, main@GOT
  78         addu    t0, gb
  79         ldw     a0, (t0, 0)
  80         lrw     t1, __libc_start_main@PLT
  81         ldr.w   t1, (gb, t1 << 0)
  82         jsr     t1
  83
  84         lrw     t1, abort@PLT
  85         ldr.w   t1, (gb, t1 << 0)
  86         jsr     t1
  87 #else
  88         /* Fetch address of __libc_csu_fini.  */
  89         lrw     a0, __libc_csu_fini
  90         /* Push __libc_csu_fini */
  91         stw     a0, (sp, 0)
  92
  93         /* Set up the other arguments in registers.  */
  94         lrw     a0, main
  95         lrw     a3, __libc_csu_init
  96         /* Let the libc call main and exit with its return code.  */
  97         jsri    __libc_start_main
  98
  99         /* Should never get here.  */
 100         jsri    abort
 101 #endif  /* !SHARED */
 102         cfi_endproc
 103         .size _start,.-_start
 104
 105
 106         /* Define a symbol for the first piece of initialized data.  */
 107         .data
 108         .globl __data_start
 109 __data_start:
 110         .long 0
 111         .weak data_start
 112         data_start = __data_start