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/* Startup code compliant to the ELF s390 ABI.
Copyright (C) 2000, 2001, 2002, 2003, 2004 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
4(%r15) argv[0]
...
(4*argc)(%r15) NULL
(4*(argc+1))(%r15) envp[0]
...
NULL
*/
.text
.globl _start
.type _start,@function
_start:
/* Setup pointer to literal pool of _start */
basr %r13,0
.L0: ahi %r13,.Llit-.L0
/* load argc and argv from stack */
la %r4,4(%r15) # get argv
l %r3,0(%r15) # get argc
/* align the stack to a double word boundary */
lhi %r0,-8
nr %r15,%r0
/* Setup a stack frame and a parameter area */
ahi %r15,-104 # make room on stack
xc 0(4,%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
*/
stm %r14,%r15,96(%r15) # store rtld_fini/stack_end to parameter area
la %r7,96(%r15)
l %r6,.L2-.Llit(%r13) # load pointer to __libc_csu_fini
l %r5,.L1-.Llit(%r13) # load pointer to __libc_csu_init
l %r2,.L3-.Llit(%r13) # load pointer to main
l %r1,.L4-.Llit(%r13) # load pointer to __libc_start_main
#ifdef PIC
l %r12,.L5-.Llit(%r13) # load .got pointer
la %r6,0(%r13,%r6)
la %r5,0(%r13,%r5)
la %r2,0(%r13,%r2)
la %r1,0(%r13,%r1)
la %r12,0(%r13,%r12)
#endif
/* ok, now branch to the libc main routine */
basr %r14,%r1
/* crash if __libc_start_main returns */
.word 0
.Llit:
#ifndef PIC
.L1: .long __libc_csu_init
.L2: .long __libc_csu_fini
.L3: .long main
.L4: .long __libc_start_main
#else
.L1: .long __libc_csu_init-.Llit
.L2: .long __libc_csu_fini-.Llit
.L3: .long main-.Llit
.L4: .long __libc_start_main@plt-.Llit
.L5: .long _GLOBAL_OFFSET_TABLE_-.Llit
#endif
/* 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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