1/* Startup code compliant to the ELF m68k ABI.
2   Copyright (C) 1996, 1997, 1998, 2001, 2002 Free Software Foundation, Inc.
3   This file is part of the GNU C Library.
4
5   The GNU C Library is free software; you can redistribute it and/or
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.
9
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
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
30   Lesser General Public License for more details.
31
32   You should have received a copy of the GNU Lesser General Public
33   License along with the GNU C Library; if not, see
34   <http://www.gnu.org/licenses/>.  */
35
36#include <features.h>
37#include "m68k_pic.S"
38
39#ifndef L_Scrt1
40/* This is the canonical entry point, usually the first thing in the text
41   segment.  The SVR4/m68k ABI says that when the entry point runs,
42   most registers' values are unspecified, except for:
43
44   %a1		Contains a function pointer to be registered with `atexit'.
45		This is how the dynamic linker arranges to have DT_FINI
46		functions called for shared libraries that have been loaded
47		before this code runs.
48
49   %sp		The stack contains the arguments and environment:
50		0(%sp)			argc
51		4(%sp)			argv[0]
52		...
53		(4*argc)(%sp)		NULL
54		(4*(argc+1))(%sp)	envp[0]
55		...
56					NULL
57
58   The uclinux conventions are different.  %a1 is not defined on entry
59   and the stack is laid out as follows:
60
61		0(%sp)			argc
62		4(%sp)			argv
63		8(%sp)			envp
64*/
65
66	.text
67	.type	_init,%function
68	.type	_fini,%function
69#ifndef __UCLIBC_CTOR_DTOR__
70	.weak	_init
71	.weak	_fini
72#endif
73	.globl _start
74	.type _start,@function
75_start:
76	/* Clear the frame pointer.  The ABI suggests this be done, to mark
77	   the outermost frame obviously.  */
78	sub.l %fp, %fp
79
80#if !defined __ARCH_USE_MMU__ && defined __PIC__
81#ifdef UCLIBC_FORMAT_ELF
82	move.l #_GLOBAL_OFFSET_TABLE_, %a5
83#else
84	/* Set up the global pointer.  The GOT is at the beginning of the
85	   data segment, whose address is in %d5.  */
86	move.l %d5,%a5
87#endif
88	.equ have_current_got, 1
89#endif
90
91#ifdef __UCLIBC_FORMAT_SHARED_FLAT__
92	CALL __shared_flat_add_library,%a1
93#endif
94
95	/* Extract the arguments as encoded on the stack and set up the
96	   arguments for `main': argc, argv.  envp will be determined
97	   later in __libc_start_main.  */
98	move.l (%sp)+, %d0	/* Pop the argument count.  */
99#if defined(__ARCH_USE_MMU__) || defined(__UCLIBC_FORMAT_ELF__)
100	move.l %sp, %a0		/* The argument vector starts just at the
101				   current stack top.  */
102#else
103	move.l (%sp)+, %a0
104#endif
105
106	/* Provide the highest stack address to the user code (for stacks
107	   which grow downward).  */
108	pea (%sp)
109
110#ifndef __ARCH_USE_MMU__
111	clr.l -(%sp)
112#else
113	pea (%a1)		/* Push address of the shared library
114				   termination function.  */
115#endif
116
117	/* Push the address of our own entry points to `.fini' and
118	   `.init'.  */
119#if defined __UCLIBC_FORMAT_SHARED_FLAT__
120	PEA_TEXT __shared_flat_fini,%a1
121	PEA_TEXT __shared_flat_init,%a1
122#else
123	PEA_TEXT _fini,%a1
124	PEA_TEXT _init,%a1
125#endif
126
127	pea (%a0)		/* Push second argument: argv.  */
128	move.l %d0, -(%sp)	/* Push first argument: argc.  */
129
130	PEA_TEXT main,%a1
131
132	/* Call the user's main function, and exit with its value.  But
133	   let the libc call main.  */
134	CALL __uClibc_main,%a1
135
136	illegal			/* Crash if somehow `exit' does return.  */
137#else
138	.text
139	.globl lib_main
140	.hidden lib_main
141	.type lib_main,@function
142lib_main:
143	move.l %d5,%a5
144	JUMP __shared_flat_add_library,%a0
145
146	.hidden _current_shared_library_a5_offset_
147#endif
148
149/* Define a symbol for the first piece of initialized data.  */
150	.data
151	.globl __data_start
152__data_start:
153	.long 0
154	.weak data_start
155	data_start = __data_start
156