glibc/sysdeps/ia64/start.S

/* Copyright (C) 1999-2020 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Written by Jes Sorensen, <Jes.Sorensen@cern.ch>, April 1999.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   In addition to the permissions in the GNU Lesser General Public
   License, the Free Software Foundation gives you unlimited
   permission to link the compiled version of this file with other
   programs, and to distribute those programs without any restriction
   coming from the use of this file. (The GNU Lesser General Public
   License restrictions do apply in other respects; for example, they
   cover modification of the file, and distribution when not linked
   into another program.)

   Note that people who make modified versions of this file are not
   obligated to grant this special exception for their modified
   versions; it is their choice whether to do so. The GNU Lesser
   General Public License gives permission to release a modified
   version without this exception; this exception also makes it
   possible to release a modified version which carries forward this
   exception.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

#include <sysdep.h>

#include <asm/fpu.h>

/*
 * Arguments for __libc_start_main:
 *	out0:	main
 *	out1:	argc
 *	out2:	argv
 *	out3:	init
 *	out4:	fini
 *	out5:	rtld_fini
 *	out6:	stack_end
 */

	.align 32
	.global _start

	.proc _start
	.type _start,@function
_start:
	.prologue
	.save rp, r0
	.body
	.prologue
	{ .mlx
	  alloc r2 = ar.pfs,0,0,7,0
	  movl r3 = FPSR_DEFAULT
	}
	{ .mlx
	  adds out2 = 16, sp	/* get address of argc value */
	  movl gp = @gprel(0f)
	  ;;
	}
0:	{ .mmi
	  ld8 out1 = [out2], 8	/* load argc and move out2 to become argv */
	  mov.m r10 = ar.bsp	/* fetch rbs base address */
	  mov r9 = ip
	  ;;
	}
	{ .mii
	  mov ar.fpsr = r3
	  sub gp = r9, gp	/* back-compute gp value */
	  adds out6 = 16, sp	/* highest non-environment stack address */
	  ;;
	}
	{
	  addl r11 = @ltoff(__libc_ia64_register_backing_store_base), gp
	  addl out0 = @ltoff(@fptr(main)), gp
	  addl out3 = @ltoff(@fptr(__libc_csu_init)), gp
	  ;;
	}
	{ .mmi
	  ld8 r3 = [r11]	/* pointer to __libc_ia64_register_backing_store_base */
	  ld8 out0 = [out0]	/* pointer to `main' function descriptor */
	  addl out4 = @ltoff(@fptr(__libc_csu_fini)), gp
	  ;;
	}
	{ .mmi
	  ld8 out3 = [out3]	/* pointer to `init' function descriptor */
	  ld8 out4 = [out4]	/* pointer to `fini' function descriptor */
	  nop 0
	}
	.body
	{ .mib
	  st8 [r3] = r10
	  mov out5 = ret0	/* dynamic linker destructor */
	  br.call.sptk.few rp = __libc_start_main
	}
	{ .mib
	  break 0	/* break miserably if we ever return */
	}
	.endp _start

/* Define a symbol for the first piece of initialized data.  */
	.data
	.globl __data_start
__data_start:
	.long 0
	.weak data_start
	data_start = __data_start

	.common __libc_ia64_register_backing_store_base, 8, 8