1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"
"http://www.w3.org/TR/REC-html40/loose.dtd">
<html>
<head>
<meta content="text/html; charset=iso-8859-1" http-equiv="Content-Type">
<title>Kernel debugging in skas mode</title>
</head>
<body alink="#FF0000" vlink="#55188A" link="#0000EF" bgcolor="#FFFFFF" text="#000099">
<table border="0">
<tr align="left">
<td valign="top">
<table border="0">
<tr align="left"><td valign="top" >
<img src="http://user-mode-linux.sourceforge.net/uml-small.png" height="171" width="120"/>
</td></tr>
<tr align="left"><td valign="top" bgcolor="#e0e0e0">
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/index.html">Site Home Page</a></font>
<br>
<font size="-1"><a href="http://uml.harlowhill.com">The UML Wiki</a></font>
<br>
<font size="-1"><a href="http://usermodelinux.org">UML Community Site</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/roadmap.html">The UML roadmap</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/uses.html">What it's good for</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/case-studies.html">Case Studies</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/kernel.html">Kernel Capabilities</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/dl-sf.html">Downloading it</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/run.html">Running it</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/compile.html">Compiling</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/install.html">Installation</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/skas.html">Skas Mode</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/patches.html">Incremental Patches</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/tests.html">Test Suite</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/devanon.html">Host memory use</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/fs_making.html">Building filesystems</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/faq.html">Troubles</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/contrib.html">User Contributions</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/links.html">Related Links</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/todo.html">The ToDo list</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/projects.html">Projects</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/diary.html">Diary</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/thanks.html">Thanks</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/contacts.html">Contacts</a></font>
</td></tr>
<tr align="left"><td valign="top" bgcolor="#e0e0e0">Tutorials<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/UserModeLinux-HOWTO.html">The HOWTO (html)</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/UserModeLinux-HOWTO.txt">The HOWTO (text)</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/hostfs.html">Host file access</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/input.html">Device inputs</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/shared_fs.html">Sharing filesystems</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/fs.html">Creating filesystems</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/resize.html">Resizing filesystems</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/networking.html">Virtual Networking</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/mconsole.html">Management Console</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/debugging.html">Kernel Debugging</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/honeypots.html">UML Honeypots</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/gprof.html">gprof and gcov</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/xtut.html">Running X</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/trouble.html">Diagnosing problems</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/config.html">Configuration</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/slack_readme.html">Installing Slackware</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/arch-port.html">Porting UML</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/iomem.html">IO memory emulation</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/2G-2G.html">UML on 2G/2G hosts</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/lksct/index.html">Adding a UML system call</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/nesting.html">Running nested UMLs</a></font>
</td></tr>
<tr align="left"><td valign="top" bgcolor="#e0e0e0">How you can help<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/help-gen.html">Overview</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/help-doc.html">Documentation</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/help-userspace.html">Utilities</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/help-kernel-v1.html">Kernel bugs</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/projects.html">Kernel projects</a></font>
</td></tr>
<tr align="left"><td valign="top" bgcolor="#e0e0e0">Screenshots<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/net.html">A virtual network</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/x.html">An X session</a></font>
</td></tr>
<tr align="left"><td valign="top" bgcolor="#e0e0e0">Transcripts<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/login.html">A login session</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/debug-session.html">A debugging session</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/slackinst.html">Slackware installation</a></font>
</td></tr>
<tr align="left"><td valign="top" bgcolor="#e0e0e0">Reference<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/switches.html">Kernel switches</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/slack_readme.html">Slackware README</a></font>
</td></tr>
<tr align="left"><td valign="top" bgcolor="#e0e0e0">Papers<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/als2000/index.html">ALS 2000 paper (html)</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/als2000.tex">ALS 2000 paper (TeX)</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/slides/als2000/slides.html">ALS 2000 slides</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/slides/lca2001/lca.html">LCA 2001 slides</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/slides/ols2001/index.html">OLS 2001 paper (html)</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/ols2001.tex">OLS 2001 paper (TeX)</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/als2001/index.html">ALS 2001 paper (html)</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/als2001.tex">ALS 2001 paper (TeX)</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/slides/ists2002/umlsec.htm">UML security (html)</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/slides/lca2002/lca2002.htm">LCA 2002 (html)</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/slides/wvu2002/wvu2002.htm">WVU 2002 (html)</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/slides/ists_rt/ists_rt.htm">Security Roundtable (html)</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/slides/ols2002/ols2002.html">OLS 2002 slides</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/slides/lwe2005/LWE2005.html">LWE 2005 slides</a></font>
</td></tr>
<tr align="left"><td valign="top" bgcolor="#e0e0e0">Fun and Games<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/cgi-bin/hangman">Kernel Hangman</a></font>
<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/sdotm.html">Disaster of the Month</a></font>
</td></tr>
</table>
</td>
<td valign="top" align="left">
<center>
<h3>Kernel debugging in skas mode</h3>
</center>
Debugging UML in skas mode is pretty much the same as debugging a
normal process, since, in skas mode, UML is pretty normal. You don't
need the 'debug' switch on the command line, and you don't get gdb
popping up in a new xterm. You start by running gdb on the UML binary
and starting it running
<blockquote>
<tt>
<font color="#000000" where="host">host% gdb linux</font>
</tt>
</blockquote>
<blockquote>
<tt>
<font color="#000000" where="host gdb">(host gdb) r
ubd0=/home/jdike/roots/cow.debian,/home/jdike/roots/debian_22
con=port:9000 ssl=pty con0=fd:0,fd:1 umid=debian mem=128M</font>
</tt>
</blockquote>
Also, have gdb ignore SIGSEGV and SUGUSR1 since these are used
internally by UML, and your debugging session would otherwise be
continually interrupted by them
<blockquote>
<tt>
<font color="#000000" where="host gdb">(host gdb) handle SIGSEGV pass nostop noprint</font>
</tt>
</blockquote>
<blockquote>
<tt>
<font color="#000000" where="host gdb">(host gdb) handle SIGUSR1 pass nostop noprint</font>
</tt>
</blockquote>
<p>
If you've enabled both CONFIG_MODE_TT and CONFIG_MODE_SKAS, UML will
exec itself, and gdb will see a SIGTRAP.
<tt>
<pre>
<font size="-1">
Program received signal SIGTRAP, Trace/breakpoint trap.
0xa000c000 in _start () at af_packet.c:1903
1903 }
(host gdb)
</font>
</pre>
</tt>
Just continue it if this happens. If CONFIG_MODE_TT is disabled, then
UML will simply boot up.
<p>
If you set any breakpoints before running UML, then all you need to do
is get UML to hit one of them, and you will be bounced back to the gdb
prompt for debugging. When you continue UML, you will be back to
whatever UML prompt you had.
<p>
If you need to interrupt UML, you can't ^C it because the terminal is
in raw mode, and the ^C will just hit whatever UML is running. What
you need to do is send the UML kernel thread a SIGINT from another
shell. It is normally the first process after the gdb
<tt>
<pre>
<font size="-1">
uml-2.5 8511: ps ux
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
jdike 7132 7.6 2.5 15356 13276 pts/2 S 15:18 0:05 gdb linux
jdike 7133 8.1 3.3 139544 17548 pts/2 R 15:18 0:05 /home/jdike/linux
jdike 7139 5.7 0.1 840 752 pts/2 T 15:19 0:00 [linux]
jdike 7144 0.2 3.3 139544 17548 pts/2 S 15:19 0:00 /home/jdike/linux
jdike 7145 0.0 3.3 139544 17548 pts/2 S 15:19 0:00 /home/jdike/linux
</font>
</pre>
</tt>
The '[linux]' process is the userspace process, and the kernel process
is the one immediately before it.
<blockquote>
<tt>
<font color="#000000" where="host">host% kill -INT 7133</font>
</tt>
</blockquote>
<tt>
<pre>
<font size="-1">
Debian GNU/Linux 2.2 usermode ttys/0
usermode login:
Program received signal SIGINT, Interrupt.
0xa019a6c1 in __libc_nanosleep ()
(gdb) bt
#0 0xa019a6c1 in __libc_nanosleep ()
#1 0xa00ed092 in idle_sleep (secs=10) at time.c:114
#2 0xa00e5765 in cpu_idle () at process_kern.c:210
#3 0xa000c50e in rest_init () at init/main.c:341
#4 0xa000356d in start_kernel () at init/main.c:435
#5 0xa00f38f7 in start_kernel_proc (unused=0x0) at process_kern.c:153
#6 0xa00e52a2 in run_kernel_thread (fn=0xa00f38d0 <start_kernel_proc>,
arg=0x0, jmp_ptr=0xa020c554) at process.c:239
#7 0xa00f36de in new_thread_handler (sig=10) at process_kern.c:67
#8 <signal handler called>
#9 0xa01891d1 in __kill ()
#10 0xa0188f85 in siglongjmp () at ../sysdeps/generic/longjmp.c:39
#11 0xa00f32e3 in start_idle_thread (stack=0xa020e000,
switch_buf_ptr=0xa020c57c, fork_buf_ptr=0xa020c580) at process.c:275
#12 0xa00f3947 in start_uml_skas () at process_kern.c:169
#13 0xa00ee779 in linux_main (argc=8, argv=0xbffff814) at um_arch.c:376
#14 0xa000c3d2 in main (argc=8, argv=0xbffff814, envp=0xbffff838)
at arch/um/main.c:143
#15 0xa0188d52 in __libc_start_main (main=0xa000c1dc <main>, argc=8,
ubp_av=0xbffff814, init=0xa01c6520 <_init>, fini=0xa01c6cb0 <_fini>,
rtld_fini=0, stack_end=0xbffff80c) at ../sysdeps/generic/libc-start.c:129
(gdb) c
Continuing.
Debian GNU/Linux 2.2 usermode ttys/0
usermode login:
</font>
</pre>
</tt>
</td>
</tr>
</table>
<center>
<font size="-1">Hosted at </font>
<a href="http://sourceforge.net">
<img src="http://sourceforge.net/sflogo.php?group_id=429" width="88" height="31" border="0" alt="SourceForge Logo">
</a>
</center>
</body>
</html>
|
