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1.1 root 1: ! crt1.s for Solaris 2, x86
2:
3: ! Copyright (C) 1993 Free Software Foundation, Inc.
4: ! Written By Fred Fish, Nov 1992
5: !
6: ! This file is free software; you can redistribute it and/or modify it
7: ! under the terms of the GNU General Public License as published by the
8: ! Free Software Foundation; either version 2, or (at your option) any
9: ! later version.
10: !
11: ! In addition to the permissions in the GNU General Public License, the
12: ! Free Software Foundation gives you unlimited permission to link the
13: ! compiled version of this file with other programs, and to distribute
14: ! those programs without any restriction coming from the use of this
15: ! file. (The General Public License restrictions do apply in other
16: ! respects; for example, they cover modification of the file, and
17: ! distribution when not linked into another program.)
18: !
19: ! This file is distributed in the hope that it will be useful, but
20: ! WITHOUT ANY WARRANTY; without even the implied warranty of
21: ! MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
22: ! General Public License for more details.
23: !
24: ! You should have received a copy of the GNU General Public License
25: ! along with this program; see the file COPYING. If not, write to
1.1.1.2 ! root 26: ! the Free Software Foundation, 59 Temple Place - Suite 330,
! 27: ! Boston, MA 02111-1307, USA.
1.1 root 28: !
29: ! As a special exception, if you link this library with files
30: ! compiled with GCC to produce an executable, this does not cause
31: ! the resulting executable to be covered by the GNU General Public License.
32: ! This exception does not however invalidate any other reasons why
33: ! the executable file might be covered by the GNU General Public License.
34: !
35:
36: ! This file takes control of the process from the kernel, as specified
37: ! in section 3 of the System V Application Binary Interface, Intel386
38: ! Processor Supplement. It has been constructed from information obtained
39: ! from the ABI, information obtained from single stepping existing
40: ! Solaris executables through their startup code with gdb, and from
41: ! information obtained by single stepping executables on other i386 SVR4
42: ! implementations. This file is the first thing linked into any executable.
43:
44: .file "crt1.s"
45: .ident "GNU C crt1.s"
46: .weak _cleanup
47: .weak _DYNAMIC
48: .text
49:
50: ! Start creating the initial frame by pushing a NULL value for the return
51: ! address of the initial frame, and mark the end of the stack frame chain
52: ! (the innermost stack frame) with a NULL value, per page 3-32 of the ABI.
53: ! Initialize the first stack frame pointer in %ebp (the contents of which
54: ! are unspecified at process initialization).
55:
56: .globl _start
57: _start:
58: pushl $0x0
59: pushl $0x0
60: movl %esp,%ebp
61:
62: ! As specified per page 3-32 of the ABI, %edx contains a function
63: ! pointer that should be registered with atexit(), for proper
64: ! shared object termination. Just push it onto the stack for now
65: ! to preserve it. We want to register _cleanup() first.
66:
67: pushl %edx
68:
69: ! Check to see if there is an _cleanup() function linked in, and if
70: ! so, register it with atexit() as the last thing to be run by
71: ! atexit().
72:
73: movl $_cleanup,%eax
74: testl %eax,%eax
75: je .L1
76: pushl $_cleanup
77: call atexit
78: addl $0x4,%esp
79: .L1:
80:
81: ! Now check to see if we have an _DYNAMIC table, and if so then
82: ! we need to register the function pointer previously in %edx, but
83: ! now conveniently saved on the stack as the argument to pass to
84: ! atexit().
85:
86: movl $_DYNAMIC,%eax
87: testl %eax,%eax
88: je .L2
89: call atexit
90: .L2:
91:
92: ! Register _fini() with atexit(). We will take care of calling _init()
93: ! directly.
94:
95: pushl $_fini
96: call atexit
97:
98: ! Compute the address of the environment vector on the stack and load
99: ! it into the global variable _environ. Currently argc is at 8 off
100: ! the frame pointer. Fetch the argument count into %eax, scale by the
101: ! size of each arg (4 bytes) and compute the address of the environment
102: ! vector which is 16 bytes (the two zero words we pushed, plus argc,
103: ! plus the null word terminating the arg vector) further up the stack,
104: ! off the frame pointer (whew!).
105:
106: movl 8(%ebp),%eax
107: leal 16(%ebp,%eax,4),%edx
108: movl %edx,_environ
109:
110: ! Push the environment vector pointer, the argument vector pointer,
111: ! and the argument count on to the stack to set up the arguments
112: ! for _init(), _fpstart(), and main(). Note that the environment
113: ! vector pointer and the arg count were previously loaded into
114: ! %edx and %eax respectively. The only new value we need to compute
115: ! is the argument vector pointer, which is at a fixed address off
116: ! the initial frame pointer.
117:
118: pushl %edx
119: leal 12(%ebp),%edx
120: pushl %edx
121: pushl %eax
122:
123: ! Call _init(argc, argv, environ), _fpstart(argc, argv, environ), and
124: ! main(argc, argv, environ).
125:
126: call _init
127: call __fpstart
128: call main
129:
130: ! Pop the argc, argv, and environ arguments off the stack, push the
131: ! value returned from main(), and call exit().
132:
133: addl $12,%esp
134: pushl %eax
135: call exit
136:
137: ! An inline equivalent of _exit, as specified in Figure 3-26 of the ABI.
138:
139: pushl $0x0
140: movl $0x1,%eax
141: lcall $7,$0
142:
143: ! If all else fails, just try a halt!
144:
145: hlt
146: .type _start,@function
147: .size _start,.-_start
148:
149: ! A dummy profiling support routine for non-profiling executables,
150: ! in case we link in some objects that have been compiled for profiling.
151:
152: .globl _mcount
153: _mcount:
154: ret
155: .type _mcount,@function
156: .size _mcount,.-_mcount
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