1#
2# This file contains a few gdb macros (user defined commands) to extract
3# useful information from kernel crashdump (kdump) like stack traces of
4# all the processes or a particular process and trapinfo.
5#
6# These macros can be used by copying this file in .gdbinit (put in home
7# directory or current directory) or by invoking gdb command with
8# --command=<command-file-name> option
9#
10# Credits:
11# Alexander Nyberg <alexn@telia.com>
12# V Srivatsa <vatsa@in.ibm.com>
13# Maneesh Soni <maneesh@in.ibm.com>
14#
15
16define bttnobp
17	set $tasks_off=((size_t)&((struct task_struct *)0)->tasks)
18	set $pid_off=((size_t)&((struct task_struct *)0)->pids[1].pid_list.next)
19	set $init_t=&init_task
20	set $next_t=(((char *)($init_t->tasks).next) - $tasks_off)
21	while ($next_t != $init_t)
22		set $next_t=(struct task_struct *)$next_t
23		printf "\npid %d; comm %s:\n", $next_t.pid, $next_t.comm
24		printf "===================\n"
25		set var $stackp = $next_t.thread.esp
26		set var $stack_top = ($stackp & ~4095) + 4096
27
28		while ($stackp < $stack_top)
29			if (*($stackp) > _stext && *($stackp) < _sinittext)
30				info symbol *($stackp)
31			end
32			set $stackp += 4
33		end
34		set $next_th=(((char *)$next_t->pids[1].pid_list.next) - $pid_off)
35		while ($next_th != $next_t)
36			set $next_th=(struct task_struct *)$next_th
37			printf "\npid %d; comm %s:\n", $next_t.pid, $next_t.comm
38			printf "===================\n"
39			set var $stackp = $next_t.thread.esp
40			set var $stack_top = ($stackp & ~4095) + 4096
41
42			while ($stackp < $stack_top)
43				if (*($stackp) > _stext && *($stackp) < _sinittext)
44					info symbol *($stackp)
45				end
46				set $stackp += 4
47			end
48			set $next_th=(((char *)$next_th->pids[1].pid_list.next) - $pid_off)
49		end
50		set $next_t=(char *)($next_t->tasks.next) - $tasks_off
51	end
52end
53document bttnobp
54	dump all thread stack traces on a kernel compiled with !CONFIG_FRAME_POINTER
55end
56
57define btt
58	set $tasks_off=((size_t)&((struct task_struct *)0)->tasks)
59	set $pid_off=((size_t)&((struct task_struct *)0)->pids[1].pid_list.next)
60	set $init_t=&init_task
61	set $next_t=(((char *)($init_t->tasks).next) - $tasks_off)
62	while ($next_t != $init_t)
63		set $next_t=(struct task_struct *)$next_t
64		printf "\npid %d; comm %s:\n", $next_t.pid, $next_t.comm
65		printf "===================\n"
66		set var $stackp = $next_t.thread.esp
67		set var $stack_top = ($stackp & ~4095) + 4096
68		set var $stack_bot = ($stackp & ~4095)
69
70		set $stackp = *($stackp)
71		while (($stackp < $stack_top) && ($stackp > $stack_bot))
72			set var $addr = *($stackp + 4)
73			info symbol $addr
74			set $stackp = *($stackp)
75		end
76
77		set $next_th=(((char *)$next_t->pids[1].pid_list.next) - $pid_off)
78		while ($next_th != $next_t)
79			set $next_th=(struct task_struct *)$next_th
80			printf "\npid %d; comm %s:\n", $next_t.pid, $next_t.comm
81			printf "===================\n"
82			set var $stackp = $next_t.thread.esp
83			set var $stack_top = ($stackp & ~4095) + 4096
84			set var $stack_bot = ($stackp & ~4095)
85
86			set $stackp = *($stackp)
87			while (($stackp < $stack_top) && ($stackp > $stack_bot))
88				set var $addr = *($stackp + 4)
89				info symbol $addr
90				set $stackp = *($stackp)
91			end
92			set $next_th=(((char *)$next_th->pids[1].pid_list.next) - $pid_off)
93		end
94		set $next_t=(char *)($next_t->tasks.next) - $tasks_off
95	end
96end
97document btt
98	dump all thread stack traces on a kernel compiled with CONFIG_FRAME_POINTER
99end
100
101define btpid
102	set var $pid = $arg0
103	set $tasks_off=((size_t)&((struct task_struct *)0)->tasks)
104	set $pid_off=((size_t)&((struct task_struct *)0)->pids[1].pid_list.next)
105	set $init_t=&init_task
106	set $next_t=(((char *)($init_t->tasks).next) - $tasks_off)
107	set var $pid_task = 0
108
109	while ($next_t != $init_t)
110		set $next_t=(struct task_struct *)$next_t
111
112		if ($next_t.pid == $pid)
113			set $pid_task = $next_t
114		end
115
116		set $next_th=(((char *)$next_t->pids[1].pid_list.next) - $pid_off)
117		while ($next_th != $next_t)
118			set $next_th=(struct task_struct *)$next_th
119			if ($next_th.pid == $pid)
120				set $pid_task = $next_th
121			end
122			set $next_th=(((char *)$next_th->pids[1].pid_list.next) - $pid_off)
123		end
124		set $next_t=(char *)($next_t->tasks.next) - $tasks_off
125	end
126
127	printf "\npid %d; comm %s:\n", $pid_task.pid, $pid_task.comm
128	printf "===================\n"
129	set var $stackp = $pid_task.thread.esp
130	set var $stack_top = ($stackp & ~4095) + 4096
131	set var $stack_bot = ($stackp & ~4095)
132
133	set $stackp = *($stackp)
134	while (($stackp < $stack_top) && ($stackp > $stack_bot))
135		set var $addr = *($stackp + 4)
136		info symbol $addr
137		set $stackp = *($stackp)
138	end
139end
140document btpid
141	backtrace of pid
142end
143
144
145define trapinfo
146	set var $pid = $arg0
147	set $tasks_off=((size_t)&((struct task_struct *)0)->tasks)
148	set $pid_off=((size_t)&((struct task_struct *)0)->pids[1].pid_list.next)
149	set $init_t=&init_task
150	set $next_t=(((char *)($init_t->tasks).next) - $tasks_off)
151	set var $pid_task = 0
152
153	while ($next_t != $init_t)
154		set $next_t=(struct task_struct *)$next_t
155
156		if ($next_t.pid == $pid)
157			set $pid_task = $next_t
158		end
159
160		set $next_th=(((char *)$next_t->pids[1].pid_list.next) - $pid_off)
161		while ($next_th != $next_t)
162			set $next_th=(struct task_struct *)$next_th
163			if ($next_th.pid == $pid)
164				set $pid_task = $next_th
165			end
166			set $next_th=(((char *)$next_th->pids[1].pid_list.next) - $pid_off)
167		end
168		set $next_t=(char *)($next_t->tasks.next) - $tasks_off
169	end
170
171	printf "Trapno %ld, cr2 0x%lx, error_code %ld\n", $pid_task.thread.trap_no, \
172				$pid_task.thread.cr2, $pid_task.thread.error_code
173
174end
175document trapinfo
176	Run info threads and lookup pid of thread #1
177	'trapinfo <pid>' will tell you by which trap & possibly
178	address the kernel panicked.
179end
180
181
182define dmesg
183	set $i = 0
184	set $end_idx = (log_end - 1) & (log_buf_len - 1)
185
186	while ($i < logged_chars)
187		set $idx = (log_end - 1 - logged_chars + $i) & (log_buf_len - 1)
188
189		if ($idx + 100 <= $end_idx) || \
190		   ($end_idx <= $idx && $idx + 100 < log_buf_len)
191			printf "%.100s", &log_buf[$idx]
192			set $i = $i + 100
193		else
194			printf "%c", log_buf[$idx]
195			set $i = $i + 1
196		end
197	end
198end
199document dmesg
200	print the kernel ring buffer
201end
202