sysdeps/ia64/start.S

   1 /* Copyright (C) 1999-2022 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    In addition to the permissions in the GNU Lesser General Public
  10    License, the Free Software Foundation gives you unlimited
  11    permission to link the compiled version of this file with other
  12    programs, and to distribute those programs without any restriction
  13    coming from the use of this file. (The GNU Lesser General Public
  14    License restrictions do apply in other respects; for example, they
  15    cover modification of the file, and distribution when not linked
  16    into another program.)
  17
  18    Note that people who make modified versions of this file are not
  19    obligated to grant this special exception for their modified
  20    versions; it is their choice whether to do so. The GNU Lesser
  21    General Public License gives permission to release a modified
  22    version without this exception; this exception also makes it
  23    possible to release a modified version which carries forward this
  24    exception.
  25
  26    The GNU C Library is distributed in the hope that it will be useful,
  27    but WITHOUT ANY WARRANTY; without even the implied warranty of
  28    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  29    Lesser General Public License for more details.
  30
  31    You should have received a copy of the GNU Lesser General Public
  32    License along with the GNU C Library; if not, see
  33    <https://www.gnu.org/licenses/>.  */
  34
  35 #include <sysdep.h>
  36
  37 #include <asm/fpu.h>
  38
  39 /*
  40  * Arguments for __libc_start_main:
  41  *      out0:   main
  42  *      out1:   argc
  43  *      out2:   argv
  44  *      out3:   init
  45  *      out4:   fini
  46  *      out5:   rtld_fini
  47  *      out6:   stack_end
  48  */
  49
  50         .align 32
  51         .global _start
  52
  53         .proc _start
  54         .type _start,@function
  55 _start:
  56         .prologue
  57         .save rp, r0
  58         .body
  59         .prologue
  60         { .mlx
  61           alloc r2 = ar.pfs,0,0,7,0
  62           movl r3 = FPSR_DEFAULT
  63         }
  64         { .mlx
  65           adds out2 = 16, sp    /* get address of argc value */
  66           movl gp = @gprel(0f)
  67           ;;
  68         }
  69 0:      { .mmi
  70           ld8 out1 = [out2], 8  /* load argc and move out2 to become argv */
  71           mov.m r10 = ar.bsp    /* fetch rbs base address */
  72           mov r9 = ip
  73           ;;
  74         }
  75         { .mii
  76           mov ar.fpsr = r3
  77           sub gp = r9, gp       /* back-compute gp value */
  78           adds out6 = 16, sp    /* highest non-environment stack address */
  79           ;;
  80         }
  81         {
  82           addl r11 = @ltoff(__libc_ia64_register_backing_store_base), gp
  83           addl out0 = @ltoff(@fptr(main)), gp
  84           mov out3 = r0         /* Used to be init.  */
  85           ;;
  86         }
  87         { .mmi
  88           ld8 r3 = [r11]        /* pointer to __libc_ia64_register_backing_store_base */
  89           ld8 out0 = [out0]     /* pointer to `main' function descriptor */
  90           mov out4 = r0         /* Used to be fini.  */
  91           ;;
  92         }
  93         .body
  94         { .mib
  95           st8 [r3] = r10
  96           mov out5 = ret0       /* dynamic linker destructor */
  97           br.call.sptk.few rp = __libc_start_main
  98         }
  99         { .mib
 100           break 0       /* break miserably if we ever return */
 101         }
 102         .endp _start
 103
 104 /* Define a symbol for the first piece of initialized data.  */
 105         .data
 106         .globl __data_start
 107 __data_start:
 108         .long 0
 109         .weak data_start
 110         data_start = __data_start
 111
 112         .common __libc_ia64_register_backing_store_base, 8, 8