1 /* crt1.s for Solaris 2, x86
3 Copyright (C) 1993-2018 Free Software Foundation, Inc.
4 Written By Fred Fish, Nov 1992
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 3, or (at your option) any
11 This file is distributed in the hope that it will be useful, but
12 WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 General Public License for more details.
16 Under Section 7 of GPL version 3, you are granted additional
17 permissions described in the GCC Runtime Library Exception, version
18 3.1, as published by the Free Software Foundation.
20 You should have received a copy of the GNU General Public License and
21 a copy of the GCC Runtime Library Exception along with this program;
22 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 <http://www.gnu.org/licenses/>. */
26 /* This file takes control of the process from the kernel, as specified
27 in section 3 of the System V Application Binary Interface, Intel386
28 Processor Supplement. It has been constructed from information obtained
29 from the ABI, information obtained from single stepping existing
30 Solaris executables through their startup code with gdb, and from
31 information obtained by single stepping executables on other i386 SVR4
32 implementations. This file is the first thing linked into any
37 #define CLEANUP _cleanup
39 /* This is a modified crt1.s by J.W.Hawtin <oolon@ankh.org> 15/8/96,
40 to allow program profiling, by calling monstartup on entry and _mcleanup
42 .ident "GNU C gcrt1.s"
43 #define CLEANUP _mcleanup
49 /* Start creating the initial frame by pushing a NULL value for the return
50 address of the initial frame, and mark the end of the stack frame chain
51 (the innermost stack frame) with a NULL value, per page 3-32 of the ABI.
52 Initialize the first stack frame pointer in %ebp (the contents of which
53 are unspecified at process initialization). */
61 /* As specified per page 3-32 of the ABI, %edx contains a function
62 pointer that should be registered with atexit(), for proper
63 shared object termination. Just push it onto the stack for now
64 to preserve it. We want to register _cleanup() first. */
68 /* Check to see if there is an _cleanup() function linked in, and if
69 so, register it with atexit() as the last thing to be run by
80 /* Now check to see if we have an _DYNAMIC table, and if so then
81 we need to register the function pointer previously in %edx, but
82 now conveniently saved on the stack as the argument to pass to
91 /* Register _fini() with atexit(). We will take care of calling _init()
98 /* Start profiling. */
109 /* Compute the address of the environment vector on the stack and load
110 it into the global variable _environ. Currently argc is at 8 off
111 the frame pointer. Fetch the argument count into %eax, scale by the
112 size of each arg (4 bytes) and compute the address of the environment
113 vector which is 16 bytes (the two zero words we pushed, plus argc,
114 plus the null word terminating the arg vector) further up the stack,
115 off the frame pointer (whew!). */
118 leal 16(%ebp,%eax,4),%edx
121 /* Push the environment vector pointer, the argument vector pointer,
122 and the argument count on to the stack to set up the arguments
123 for _init(), _fpstart(), and main(). Note that the environment
124 vector pointer and the arg count were previously loaded into
125 %edx and %eax respectively. The only new value we need to compute
126 is the argument vector pointer, which is at a fixed address off
127 the initial frame pointer. */
129 /* Make sure the stack is properly aligned. */
130 andl $0xfffffff0,%esp
138 /* Call _init(argc, argv, environ), _fpstart(argc, argv, environ), and
139 main(argc, argv, environ). */
145 /* Pop the argc, argv, and environ arguments off the stack, push the
146 value returned from main(), and call exit(). */
152 /* An inline equivalent of _exit, as specified in Figure 3-26 of the ABI. */
158 /* If all else fails, just try a halt! */
161 .type _start,@function
162 .size _start,.-_start
165 /* A dummy profiling support routine for non-profiling executables,
166 in case we link in some objects that have been compiled for profiling. */
171 .type _mcount,@function
172 .size _mcount,.-_mcount