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/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                         sprintf(buf, "btt 0x%px\n", KDB_TSK(cpu));
 190                         kdb_parse(buf);
 191                         touch_nmi_watchdog();
 192                 }
 193                 kdb_set_current_task(save_current_task);
 194                 return 0;
 195         } else {
 196                 if (argc) {
 197                         nextarg = 1;
 198                         diag = kdbgetaddrarg(argc, argv, &nextarg, &addr,
 199                                              &offset, NULL);
 200                         if (diag)
 201                                 return diag;
 202                         kdb_show_stack(kdb_current_task, (void *)addr);
 203                         return 0;
 204                 } else {
 205                         return kdb_bt1(kdb_current_task, ~0UL, argcount, 0);
 206                 }
 207         }
 208
 209         /* NOTREACHED */
 210         return 0;
 211 }