kernel/debug/kdb/kdb_bt.c

   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
  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
  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
 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 }