1 /*
2 * Kernel Debugger Architecture Independent Stack Traceback
3 *
4 * This file is subject to the terms and conditions of the GNU General Public
5 * License. See the file "COPYING" in the main directory of this archive
6 * for more details.
7 *
8 * Copyright (c) 1999-2004 Silicon Graphics, Inc. All Rights Reserved.
9 * Copyright (c) 2009 Wind River Systems, Inc. All Rights Reserved.
10 */
11
12 #include <linux/ctype.h>
13 #include <linux/string.h>
14 #include <linux/kernel.h>
15 #include <linux/sched/signal.h>
16 #include <linux/sched/debug.h>
17 #include <linux/kdb.h>
18 #include <linux/nmi.h>
19 #include "kdb_private.h"
20
21
22 static void kdb_show_stack(struct task_struct *p, void *addr)
23 {
24 int old_lvl = console_loglevel;
25 console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH;
26 kdb_trap_printk++;
27 kdb_set_current_task(p);
28 if (addr) {
29 show_stack((struct task_struct *)p, addr);
30 } else if (kdb_current_regs) {
31 #ifdef CONFIG_X86
32 show_stack(p, &kdb_current_regs->sp);
33 #else
34 show_stack(p, NULL);
35 #endif
36 } else {
37 show_stack(p, NULL);
38 }
39 console_loglevel = old_lvl;
40 kdb_trap_printk--;
41 }
42
43 /*
44 * kdb_bt
45 *
46 * This function implements the 'bt' command. Print a stack
47 * traceback.
48 *
49 * bt [<address-expression>] (addr-exp is for alternate stacks)
50 * btp <pid> Kernel stack for <pid>
51 * btt <address-expression> Kernel stack for task structure at
52 * <address-expression>
53 * bta [DRSTCZEUIMA] All useful processes, optionally
54 * filtered by state
55 * btc [<cpu>] The current process on one cpu,
56 * default is all cpus
57 *
58 * bt <address-expression> refers to a address on the stack, that location
59 * is assumed to contain a return address.
60 *
61 * btt <address-expression> refers to the address of a struct task.
62 *
63 * Inputs:
64 * argc argument count
65 * argv argument vector
66 * Outputs:
67 * None.
68 * Returns:
69 * zero for success, a kdb diagnostic if error
70 * Locking:
71 * none.
72 * Remarks:
73 * Backtrack works best when the code uses frame pointers. But even
74 * without frame pointers we should get a reasonable trace.
75 *
76 * mds comes in handy when examining the stack to do a manual traceback or
77 * to get a starting point for bt <address-expression>.
78 */
79
80 static int
81 kdb_bt1(struct task_struct *p, unsigned long mask,
82 int argcount, int btaprompt)
83 {
84 char buffer[2];
85 if (kdb_getarea(buffer[0], (unsigned long)p) ||
86 kdb_getarea(buffer[0], (unsigned long)(p+1)-1))
87 return KDB_BADADDR;
88 if (!kdb_task_state(p, mask))
89 return 0;
90 kdb_printf("Stack traceback for pid %d\n", p->pid);
91 kdb_ps1(p);
92 kdb_show_stack(p, NULL);
93 if (btaprompt) {
94 kdb_getstr(buffer, sizeof(buffer),
95 "Enter <q> to end, <cr> to continue:");
96 if (buffer[0] == 'q') {
97 kdb_printf("\n");
98 return 1;
99 }
100 }
101 touch_nmi_watchdog();
102 return 0;
103 }
104
105 int
106 kdb_bt(int argc, const char **argv)
107 {
108 int diag;
109 int argcount = 5;
110 int btaprompt = 1;
111 int nextarg;
112 unsigned long addr;
113 long offset;
114
115 /* Prompt after each proc in bta */
116 kdbgetintenv("BTAPROMPT", &btaprompt);
117
118 if (strcmp(argv[0], "bta") == 0) {
119 struct task_struct *g, *p;
120 unsigned long cpu;
121 unsigned long mask = kdb_task_state_string(argc ? argv[1] :
122 NULL);
123 if (argc == 0)
124 kdb_ps_suppressed();
125 /* Run the active tasks first */
126 for_each_online_cpu(cpu) {
127 p = kdb_curr_task(cpu);
128 if (kdb_bt1(p, mask, argcount, btaprompt))
129 return 0;
130 }
131 /* Now the inactive tasks */
132 kdb_do_each_thread(g, p) {
133 if (KDB_FLAG(CMD_INTERRUPT))
134 return 0;
135 if (task_curr(p))
136 continue;
137 if (kdb_bt1(p, mask, argcount, btaprompt))
138 return 0;
139 } kdb_while_each_thread(g, p);
140 } else if (strcmp(argv[0], "btp") == 0) {
141 struct task_struct *p;
142 unsigned long pid;
143 if (argc != 1)
144 return KDB_ARGCOUNT;
145 diag = kdbgetularg((char *)argv[1], &pid);
146 if (diag)
147 return diag;
148 p = find_task_by_pid_ns(pid, &init_pid_ns);
149 if (p) {
150 kdb_set_current_task(p);
151 return kdb_bt1(p, ~0UL, argcount, 0);
152 }
153 kdb_printf("No process with pid == %ld found\n", pid);
154 return 0;
155 } else if (strcmp(argv[0], "btt") == 0) {
156 if (argc != 1)
157 return KDB_ARGCOUNT;
158 diag = kdbgetularg((char *)argv[1], &addr);
159 if (diag)
160 return diag;
161 kdb_set_current_task((struct task_struct *)addr);
162 return kdb_bt1((struct task_struct *)addr, ~0UL, argcount, 0);
163 } else if (strcmp(argv[0], "btc") == 0) {
164 unsigned long cpu = ~0;
165 struct task_struct *save_current_task = kdb_current_task;
166 char buf[80];
167 if (argc > 1)
168 return KDB_ARGCOUNT;
169 if (argc == 1) {
170 diag = kdbgetularg((char *)argv[1], &cpu);
171 if (diag)
172 return diag;
173 }
174 /* Recursive use of kdb_parse, do not use argv after
175 * this point */
176 argv = NULL;
177 if (cpu != ~0) {
178 if (cpu >= num_possible_cpus() || !cpu_online(cpu)) {
179 kdb_printf("no process for cpu %ld\n", cpu);
180 return 0;
181 }
182 sprintf(buf, "btt 0x%px\n", KDB_TSK(cpu));
183 kdb_parse(buf);
184 return 0;
185 }
186 kdb_printf("btc: cpu status: ");
187 kdb_parse("cpu\n");
188 for_each_online_cpu(cpu) {
189 void *kdb_tsk = KDB_TSK(cpu);
190
191 /* If a CPU failed to round up we could be here */
192 if (!kdb_tsk) {
193 kdb_printf("WARNING: no task for cpu %ld\n",
194 cpu);
195 continue;
196 }
197
198 sprintf(buf, "btt 0x%px\n", kdb_tsk);
199 kdb_parse(buf);
200 touch_nmi_watchdog();
201 }
202 kdb_set_current_task(save_current_task);
203 return 0;
204 } else {
205 if (argc) {
206 nextarg = 1;
207 diag = kdbgetaddrarg(argc, argv, &nextarg, &addr,
208 &offset, NULL);
209 if (diag)
210 return diag;
211 kdb_show_stack(kdb_current_task, (void *)addr);
212 return 0;
213 } else {
214 return kdb_bt1(kdb_current_task, ~0UL, argcount, 0);
215 }
216 }
217
218 /* NOTREACHED */
219 return 0;
220 }