aboutsummaryrefslogtreecommitdiff
path: root/kernel/debug/kdb/kdb_bt.c
blob: 0e94efe07b729873c76e5c7180cb8976a2d64c63 (plain)
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
/*
 * Kernel Debugger Architecture Independent Stack Traceback
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (c) 1999-2004 Silicon Graphics, Inc.  All Rights Reserved.
 * Copyright (c) 2009 Wind River Systems, Inc.  All Rights Reserved.
 */

#include <linux/ctype.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/sched/signal.h>
#include <linux/sched/debug.h>
#include <linux/kdb.h>
#include <linux/nmi.h>
#include "kdb_private.h"


static void kdb_show_stack(struct task_struct *p, void *addr)
{
	int old_lvl = console_loglevel;

	console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH;
	kdb_trap_printk++;

	if (!addr && kdb_task_has_cpu(p))
		kdb_dump_stack_on_cpu(kdb_process_cpu(p));
	else
		show_stack(p, addr);

	console_loglevel = old_lvl;
	kdb_trap_printk--;
}

/*
 * kdb_bt
 *
 *	This function implements the 'bt' command.  Print a stack
 *	traceback.
 *
 *	bt [<address-expression>]	(addr-exp is for alternate stacks)
 *	btp <pid>			Kernel stack for <pid>
 *	btt <address-expression>	Kernel stack for task structure at
 *					<address-expression>
 *	bta [DRSTCZEUIMA]		All useful processes, optionally
 *					filtered by state
 *	btc [<cpu>]			The current process on one cpu,
 *					default is all cpus
 *
 *	bt <address-expression> refers to a address on the stack, that location
 *	is assumed to contain a return address.
 *
 *	btt <address-expression> refers to the address of a struct task.
 *
 * Inputs:
 *	argc	argument count
 *	argv	argument vector
 * Outputs:
 *	None.
 * Returns:
 *	zero for success, a kdb diagnostic if error
 * Locking:
 *	none.
 * Remarks:
 *	Backtrack works best when the code uses frame pointers.  But even
 *	without frame pointers we should get a reasonable trace.
 *
 *	mds comes in handy when examining the stack to do a manual traceback or
 *	to get a starting point for bt <address-expression>.
 */

static int
kdb_bt1(struct task_struct *p, unsigned long mask, bool btaprompt)
{
	char buffer[2];
	if (kdb_getarea(buffer[0], (unsigned long)p) ||
	    kdb_getarea(buffer[0], (unsigned long)(p+1)-1))
		return KDB_BADADDR;
	if (!kdb_task_state(p, mask))
		return 0;
	kdb_printf("Stack traceback for pid %d\n", p->pid);
	kdb_ps1(p);
	kdb_show_stack(p, NULL);
	if (btaprompt) {
		kdb_getstr(buffer, sizeof(buffer),
			   "Enter <q> to end, <cr> to continue:");
		if (buffer[0] == 'q') {
			kdb_printf("\n");
			return 1;
		}
	}
	touch_nmi_watchdog();
	return 0;
}

static void
kdb_bt_cpu(unsigned long cpu)
{
	struct task_struct *kdb_tsk;

	if (cpu >= num_possible_cpus() || !cpu_online(cpu)) {
		kdb_printf("WARNING: no process for cpu %ld\n", cpu);
		return;
	}

	/* If a CPU failed to round up we could be here */
	kdb_tsk = KDB_TSK(cpu);
	if (!kdb_tsk) {
		kdb_printf("WARNING: no task for cpu %ld\n", cpu);
		return;
	}

	kdb_set_current_task(kdb_tsk);
	kdb_bt1(kdb_tsk, ~0UL, false);
}

int
kdb_bt(int argc, const char **argv)
{
	int diag;
	int btaprompt = 1;
	int nextarg;
	unsigned long addr;
	long offset;

	/* Prompt after each proc in bta */
	kdbgetintenv("BTAPROMPT", &btaprompt);

	if (strcmp(argv[0], "bta") == 0) {
		struct task_struct *g, *p;
		unsigned long cpu;
		unsigned long mask = kdb_task_state_string(argc ? argv[1] :
							   NULL);
		if (argc == 0)
			kdb_ps_suppressed();
		/* Run the active tasks first */
		for_each_online_cpu(cpu) {
			p = kdb_curr_task(cpu);
			if (kdb_bt1(p, mask, btaprompt))
				return 0;
		}
		/* Now the inactive tasks */
		kdb_do_each_thread(g, p) {
			if (KDB_FLAG(CMD_INTERRUPT))
				return 0;
			if (task_curr(p))
				continue;
			if (kdb_bt1(p, mask, btaprompt))
				return 0;
		} kdb_while_each_thread(g, p);
	} else if (strcmp(argv[0], "btp") == 0) {
		struct task_struct *p;
		unsigned long pid;
		if (argc != 1)
			return KDB_ARGCOUNT;
		diag = kdbgetularg((char *)argv[1], &pid);
		if (diag)
			return diag;
		p = find_task_by_pid_ns(pid, &init_pid_ns);
		if (p) {
			kdb_set_current_task(p);
			return kdb_bt1(p, ~0UL, false);
		}
		kdb_printf("No process with pid == %ld found\n", pid);
		return 0;
	} else if (strcmp(argv[0], "btt") == 0) {
		if (argc != 1)
			return KDB_ARGCOUNT;
		diag = kdbgetularg((char *)argv[1], &addr);
		if (diag)
			return diag;
		kdb_set_current_task((struct task_struct *)addr);
		return kdb_bt1((struct task_struct *)addr, ~0UL, false);
	} else if (strcmp(argv[0], "btc") == 0) {
		unsigned long cpu = ~0;
		struct task_struct *save_current_task = kdb_current_task;
		if (argc > 1)
			return KDB_ARGCOUNT;
		if (argc == 1) {
			diag = kdbgetularg((char *)argv[1], &cpu);
			if (diag)
				return diag;
		}
		if (cpu != ~0) {
			kdb_bt_cpu(cpu);
		} else {
			/*
			 * Recursive use of kdb_parse, do not use argv after
			 * this point.
			 */
			argv = NULL;
			kdb_printf("btc: cpu status: ");
			kdb_parse("cpu\n");
			for_each_online_cpu(cpu) {
				kdb_bt_cpu(cpu);
				touch_nmi_watchdog();
			}
			kdb_set_current_task(save_current_task);
		}
		return 0;
	} else {
		if (argc) {
			nextarg = 1;
			diag = kdbgetaddrarg(argc, argv, &nextarg, &addr,
					     &offset, NULL);
			if (diag)
				return diag;
			kdb_show_stack(kdb_current_task, (void *)addr);
			return 0;
		} else {
			return kdb_bt1(kdb_current_task, ~0UL, false);
		}
	}

	/* NOTREACHED */
	return 0;
}