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/* Startup code compliant to the 64 bit S/390 ELF ABI.
Copyright (C) 2001, 2002 Free Software Foundation, Inc.
Contributed by Martin Schwidefsky (schwidefsky@de.ibm.com).
This file is part of the GNU C Library.
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.
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, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
/*
This is the canonical entry point, usually the first thing in the text
segment. Most registers' values are unspecified, except for:
%r14 Contains a function pointer to be registered with `atexit'.
This is how the dynamic linker arranges to have DT_FINI
functions called for shared libraries that have been loaded
before this code runs.
%r15 The stack contains the arguments and environment:
0(%r15) argc
8(%r15) argv[0]
...
(8*argc)(%r15) NULL
(8*(argc+1))(%r15) envp[0]
...
NULL
*/
.text
.globl _start
.type _start,@function
_start:
/* Load argc and argv from stack. */
la %r4,8(%r15) # get argv
lg %r3,0(%r15) # get argc
/* Align the stack to a double word boundary. */
lghi %r0,-16
ngr %r15,%r0
/* Setup a stack frame and a parameter area. */
aghi %r15,-176 # make room on stack
xc 0(8,%r15),0(%r15) # clear back-chain
/* Set up arguments for __libc_start_main:
main, argc, argv, envp, _init, _fini, rtld_fini, stack_end
Note that envp will be determined later in __libc_start_main.
*/
stmg %r14,%r15,160(%r15) # store rtld_fini/stack_end to parameter area
la %r7,160(%r15)
larl %r6,__libc_csu_fini # load pointer to __libc_csu_fini
larl %r5,__libc_csu_init # load pointer to __libc_csu_init
larl %r2,main # load pointer to main
/* Ok, now branch to the libc main routine. */
brasl %r14,__libc_start_main
/* Crash if __libc_start_main returns. */
.word 0
/* FIXME: FPU flags or what ?!? */
.section .rodata
.globl _fp_hw
.long 3
.size _fp_hw, 4
/* 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
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