Blame sysdeps/m68k/start.S

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/* Startup code compliant to the ELF m68k ABI.
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   Copyright (C) 1996-2018 Free Software Foundation, Inc.
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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, see
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   <http://www.gnu.org/licenses/>.  */
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/* This is the canonical entry point, usually the first thing in the text
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   segment.  The SVR4/m68k ABI says that when the entry point runs,
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   most registers' values are unspecified, except for:
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   %a1		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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   %sp		The stack contains the arguments and environment:
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		0(%sp)			argc
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		4(%sp)			argv[0]
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		...
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		(4*argc)(%sp)		NULL
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		(4*(argc+1))(%sp)	envp[0]
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		...
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					NULL
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*/
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#include <sysdep.h>
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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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	/* Clear the frame pointer.  The ABI suggests this be done, to mark
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	   the outermost frame obviously.  */
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	sub.l %fp, %fp
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	/* Extract the arguments as encoded on the stack and set up the
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	   arguments for `main': argc, argv.  envp will be determined
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	   later in __libc_start_main.  */
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	move.l (%sp)+, %d0	/* Pop the argument count.  */
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	move.l %sp, %a0		/* The argument vector starts just at the
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				   current stack top.  */
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	/* Provide the highest stack address to the user code (for stacks
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	   which grow downward).  */
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	pea (%sp)
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	pea (%a1)		/* Push address of the shared library
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				   termination function.  */
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#ifdef PIC
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	/* Load PIC register.  */
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	LOAD_GOT (%a5)
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	/* Push the address of our own entry points to `.fini' and
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	   `.init'.  */
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	move.l __libc_csu_fini@GOT(%a5), -(%sp)
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	move.l __libc_csu_init@GOT(%a5), -(%sp)
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	pea (%a0)		/* Push second argument: argv.  */
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	move.l %d0, -(%sp)	/* Push first argument: argc.  */
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	move.l main@GOT(%a5), -(%sp)
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	/* Call the user's main function, and exit with its value.  But
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	   let the libc call main.  */
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	jbsr __libc_start_main@PLTPC
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#else
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	/* Push the address of our own entry points to `.fini' and
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	   `.init'.  */
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	pea __libc_csu_fini
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	pea __libc_csu_init
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	pea (%a0)		/* Push second argument: argv.  */
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	move.l %d0, -(%sp)	/* Push first argument: argc.  */
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	pea main
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	/* Call the user's main function, and exit with its value.  But
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	   let the libc call main.  */
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	jbsr __libc_start_main
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#endif
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	illegal			/* Crash if somehow `exit' does return.  */
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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