• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
1/* -----------------------------------------------------------------------
2 *
3 *   Copyright 2003-2008 H. Peter Anvin - All Rights Reserved
4 *
5 *   Permission is hereby granted, free of charge, to any person
6 *   obtaining a copy of this software and associated documentation
7 *   files (the "Software"), to deal in the Software without
8 *   restriction, including without limitation the rights to use,
9 *   copy, modify, merge, publish, distribute, sublicense, and/or
10 *   sell copies of the Software, and to permit persons to whom
11 *   the Software is furnished to do so, subject to the following
12 *   conditions:
13 *
14 *   The above copyright notice and this permission notice shall
15 *   be included in all copies or substantial portions of the Software.
16 *
17 *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
18 *   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
19 *   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
20 *   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
21 *   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
22 *   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
23 *   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
24 *   OTHER DEALINGS IN THE SOFTWARE.
25 *
26 * ----------------------------------------------------------------------- */
27
28/*
29 * COM32 start up code - must be linked first in the binary
30 */
31
32/* Number of arguments in our version of the entry structure */
33#define COM32_ARGS 9
34
35		.section ".init","ax"
36		.globl _start
37		.type _start, @function
38_start:
39		/* This first instruction acts as COM32R magic number */
40		movl $0x21cd4cfe,%eax
41
42		/* Upwards string operations */
43		cld
44
45		/* Find our own location */
46		call 1f
471:		popl %ebx
48		addl $_GLOBAL_OFFSET_TABLE_ + (. - 1b), %ebx
49
50		/* Process relocations (which overlay the .bss segment) */
51		leal _edata@GOTOFF(%ebx),%esi
52		leal _start@GOTOFF(%ebx),%edx
532:		lodsl
54		andl %eax,%eax
55		jz 3f
56		addl %edx,(%eax,%edx)
57		jmp 2b
583:
59		/* Relocate the GOT (is this right?) */
60		leal __got_start@GOTOFF(%ebx),%esi
61		leal __got_end@GOTOFF(%ebx),%edi
624:
63		addl %edx,(%esi)
64		addl $4,%esi
65		cmpl %edi,%esi
66		jb 4b
67
68		/* Zero the .bss segment */
69		xorl %eax,%eax
70		leal __bss_start@GOTOFF(%ebx),%edi
71		leal _end+3@GOTOFF(%ebx),%ecx
72		subl %edi,%ecx
73		shrl $2,%ecx
74		rep ; stosl
75
76		/* Copy COM32 invocation parameters */
77		leal 4(%esp),%esi		# Argument list
78		leal __com32@GOTOFF(%ebx),%edi
79		movl $(COM32_ARGS),%ecx
80		movl %esp,-4(%edi)		# Save the initial stack ptr
81		cmpl (%esi),%ecx
82		jbe 5f
83		movl (%esi),%ecx
845:		inc %ecx			# Copy the argument count, too
85		rep ; movsl
86
87		/* Parse the command line (assumes REGPARM) */
88		movl __com32+4@GOTOFF(%ebx),%edx	# Command line
89		pushl %edx				# Make space for argv
90		movl %esp,%eax
91		call __parse_argv
92		pushl %eax				# Save argc
93
94		/* Look for library initialization functions */
95		leal __ctors_start@GOTOFF(%ebx),%esi
96		leal __ctors_end@GOTOFF(%ebx),%edi
976:
98		cmpl %edi,%esi
99		jae 7f
100		call *(%esi)
101		addl $4,%esi
102		jmp 6b
103/*
104 * Actually run main.  This assumes REGPARM is used!!!!
105 */
1067:
107		popl %eax			# argc
108		popl %edx			# argv
109		call main
110		call *__exit_handler@GOTOFF(%ebx)
111		hlt
112		.size _start, .-_start
113
114		.bss
115		.globl __entry_esp
116__entry_esp:	.space 4
117		.globl __com32
118__com32:	.space 4*(COM32_ARGS+1)
119