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