[thirdparty/glibc.git] / sysdeps / m68k / start.S

/* Startup code compliant to the ELF m68k ABI.
   Copyright (C) 1996-2019 Free Software Foundation, Inc.
   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.

   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/>.  */

/* This is the canonical entry point, usually the first thing in the text
   segment.  The SVR4/m68k ABI says that when the entry point runs,
   most registers' values are unspecified, except for:

   %a1		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.

   %sp		The stack contains the arguments and environment:
		0(%sp)			argc
		4(%sp)			argv[0]
		...
		(4*argc)(%sp)		NULL
		(4*(argc+1))(%sp)	envp[0]
		...
					NULL
*/

#include <sysdep.h>

	.text
	.globl _start
	.type _start,@function
_start:
	/* Clear the frame pointer.  The ABI suggests this be done, to mark
	   the outermost frame obviously.  */
	sub.l %fp, %fp

	/* Extract the arguments as encoded on the stack and set up the
	   arguments for `main': argc, argv.  envp will be determined
	   later in __libc_start_main.  */
	move.l (%sp)+, %d0	/* Pop the argument count.  */
	move.l %sp, %a0		/* The argument vector starts just at the
				   current stack top.  */

	/* Provide the highest stack address to the user code (for stacks
	   which grow downward).  */
	pea (%sp)

	pea (%a1)		/* Push address of the shared library
				   termination function.  */

#ifdef PIC
	/* Load PIC register.  */
	LOAD_GOT (%a5)

	/* Push the address of our own entry points to `.fini' and
	   `.init'.  */
	move.l __libc_csu_fini@GOT(%a5), -(%sp)
	move.l __libc_csu_init@GOT(%a5), -(%sp)

	pea (%a0)		/* Push second argument: argv.  */
	move.l %d0, -(%sp)	/* Push first argument: argc.  */

	move.l main@GOT(%a5), -(%sp)

	/* Call the user's main function, and exit with its value.  But
	   let the libc call main.  */
	jbsr __libc_start_main@PLTPC
#else
	/* Push the address of our own entry points to `.fini' and
	   `.init'.  */
	pea __libc_csu_fini
	pea __libc_csu_init

	pea (%a0)		/* Push second argument: argv.  */
	move.l %d0, -(%sp)	/* Push first argument: argc.  */

	pea main

	/* Call the user's main function, and exit with its value.  But
	   let the libc call main.  */
	jbsr __libc_start_main
#endif

	illegal			/* Crash if somehow `exit' does return.  */

/* 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
Commit	Line	Data
5f51e113	1	/* Startup code compliant to the ELF m68k ABI.
04277e02	2	Copyright (C) 1996-2019 Free Software Foundation, Inc.
fb1efdea	3	This file is part of the GNU C Library.
5f51e113	4
fb1efdea	5	The GNU C Library is free software; you can redistribute it and/or
3214b89b AJ	6	modify it under the terms of the GNU Lesser General Public
	7	License as published by the Free Software Foundation; either
	8	version 2.1 of the License, or (at your option) any later version.
5f51e113	9
0bec0145 RM	10	In addition to the permissions in the GNU Lesser General Public
	11	License, the Free Software Foundation gives you unlimited
	12	permission to link the compiled version of this file with other
	13	programs, and to distribute those programs without any restriction
	14	coming from the use of this file. (The GNU Lesser General Public
	15	License restrictions do apply in other respects; for example, they
	16	cover modification of the file, and distribution when not linked
	17	into another program.)
	18
	19	Note that people who make modified versions of this file are not
	20	obligated to grant this special exception for their modified
	21	versions; it is their choice whether to do so. The GNU Lesser
	22	General Public License gives permission to release a modified
	23	version without this exception; this exception also makes it
	24	possible to release a modified version which carries forward this
	25	exception.
	26
fb1efdea UD	27	The GNU C Library is distributed in the hope that it will be useful,
	28	but WITHOUT ANY WARRANTY; without even the implied warranty of
	29	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
3214b89b	30	Lesser General Public License for more details.
5f51e113	31
3214b89b	32	You should have received a copy of the GNU Lesser General Public
ab84e3ff	33	License along with the GNU C Library. If not, see
5a82c748	34	<https://www.gnu.org/licenses/>. */
5f51e113 RM	35
	36	/* This is the canonical entry point, usually the first thing in the text
	37	segment. The SVR4/m68k ABI says that when the entry point runs,
	38	most registers' values are unspecified, except for:
	39
	40	%a1 Contains a function pointer to be registered with `atexit'.
fb1efdea	41	This is how the dynamic linker arranges to have DT_FINI
5f51e113 RM	42	functions called for shared libraries that have been loaded
	43	before this code runs.
	44
	45	%sp The stack contains the arguments and environment:
fb1efdea	46	0(%sp) argc
5f51e113 RM	47	4(%sp) argv[0]
	48	...
	49	(4*argc)(%sp) NULL
	50	(4*(argc+1))(%sp) envp[0]
	51	...
	52	NULL
	53	*/
	54
ed4c9939 AS	55	#include <sysdep.h>
ed4c9939 AS	56
fb1efdea	57	.text
5f51e113	58	.globl _start
13906e12	59	.type _start,@function
5f51e113 RM	60	_start:
	61	/* Clear the frame pointer. The ABI suggests this be done, to mark
	62	the outermost frame obviously. */
	63	sub.l %fp, %fp
	64
69235f76 AS	65	/* Extract the arguments as encoded on the stack and set up the
	66	arguments for `main': argc, argv. envp will be determined
	67	later in __libc_start_main. */
	68	move.l (%sp)+, %d0 /* Pop the argument count. */
	69	move.l %sp, %a0 /* The argument vector starts just at the
	70	current stack top. */
5f51e113	71
08016d92 AS	72	/* Provide the highest stack address to the user code (for stacks
	73	which grow downward). */
	74	pea (%sp)
	75
69235f76 AS	76	pea (%a1) /* Push address of the shared library
69235f76 AS	77	termination function. */
5f51e113	78
4027a4fd	79	#ifdef PIC
ed4c9939 AS	80	/* Load PIC register. */
	81	LOAD_GOT (%a5)
	82
	83	/* Push the address of our own entry points to `.fini' and
	84	`.init'. */
	85	move.l __libc_csu_fini@GOT(%a5), -(%sp)
	86	move.l __libc_csu_init@GOT(%a5), -(%sp)
	87
	88	pea (%a0) /* Push second argument: argv. */
	89	move.l %d0, -(%sp) /* Push first argument: argc. */
	90
	91	move.l main@GOT(%a5), -(%sp)
	92
	93	/* Call the user's main function, and exit with its value. But
	94	let the libc call main. */
7d0c5ed0	95	jbsr __libc_start_main@PLTPC
ed4c9939	96	#else
69235f76 AS	97	/* Push the address of our own entry points to `.fini' and
69235f76 AS	98	`.init'. */
f8a26bed RM	99	pea __libc_csu_fini
f8a26bed RM	100	pea __libc_csu_init
69235f76 AS	101
69235f76 AS	102	pea (%a0) /* Push second argument: argv. */
5f51e113 RM	103	move.l %d0, -(%sp) /* Push first argument: argc. */
5f51e113 RM	104
69235f76 AS	105	pea main
	106
	107	/* Call the user's main function, and exit with its value. But
	108	let the libc call main. */
	109	jbsr __libc_start_main
ed4c9939	110	#endif
5f51e113	111
69235f76	112	illegal /* Crash if somehow `exit' does return. */
5f51e113 RM	113
	114	/* Define a symbol for the first piece of initialized data. */
	115	.data
	116	.globl __data_start
	117	__data_start:
	118	.long 0
	119	.weak data_start
	120	data_start = __data_start