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100 lines
3.5 KiB
ArmAsm
100 lines
3.5 KiB
ArmAsm
/* Startup code compliant to the 64 bit S/390 ELF ABI.
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Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
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Contributed by Martin Schwidefsky (schwidefsky@de.ibm.com).
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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In addition to the permissions in the GNU Lesser General Public
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License, the Free Software Foundation gives you unlimited
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permission to link the compiled version of this file with other
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programs, and to distribute those programs without any restriction
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coming from the use of this file. (The GNU Lesser General Public
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License restrictions do apply in other respects; for example, they
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cover modification of the file, and distribution when not linked
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into another program.)
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Note that people who make modified versions of this file are not
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obligated to grant this special exception for their modified
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versions; it is their choice whether to do so. The GNU Lesser
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General Public License gives permission to release a modified
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version without this exception; this exception also makes it
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possible to release a modified version which carries forward this
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exception.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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/*
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This is the canonical entry point, usually the first thing in the text
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segment. Most registers' values are unspecified, except for:
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%r14 Contains a function pointer to be registered with `atexit'.
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This is how the dynamic linker arranges to have DT_FINI
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functions called for shared libraries that have been loaded
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before this code runs.
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%r15 The stack contains the arguments and environment:
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0(%r15) argc
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8(%r15) argv[0]
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...
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(8*argc)(%r15) NULL
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(8*(argc+1))(%r15) envp[0]
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...
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NULL
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*/
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.text
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.globl _start
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.type _start,@function
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_start:
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/* Load argc and argv from stack. */
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la %r4,8(%r15) # get argv
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lg %r3,0(%r15) # get argc
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/* Align the stack to a double word boundary. */
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lghi %r0,-16
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ngr %r15,%r0
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/* Setup a stack frame and a parameter area. */
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aghi %r15,-176 # make room on stack
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xc 0(8,%r15),0(%r15) # clear back-chain
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/* Set up arguments for __libc_start_main:
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main, argc, argv, envp, _init, _fini, rtld_fini, stack_end
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Note that envp will be determined later in __libc_start_main.
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*/
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stmg %r14,%r15,160(%r15) # store rtld_fini/stack_end to parameter area
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la %r7,160(%r15)
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larl %r6,__libc_csu_fini # load pointer to __libc_csu_fini
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larl %r5,__libc_csu_init # load pointer to __libc_csu_init
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larl %r2,main # load pointer to main
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/* Ok, now branch to the libc main routine. */
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#ifdef PIC
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brasl %r14,__libc_start_main@plt
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#else
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brasl %r14,__libc_start_main
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#endif
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/* Crash if __libc_start_main returns. */
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.word 0
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/* Define a symbol for the first piece of initialized data. */
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.data
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.globl __data_start
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__data_start:
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.long 0
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.weak data_start
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data_start = __data_start
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