Documentation/kdump/gdbmacros.txt

   1 #
   2 # This file contains a few gdb macros (user defined commands) to extract
   3 # useful information from kernel crashdump (kdump) like stack traces of
   4 # all the processes or a particular process and trapinfo.
   5 #
   6 # These macros can be used by copying this file in .gdbinit (put in home
   7 # directory or current directory) or by invoking gdb command with
   8 # --command=<command-file-name> option
   9 #
  10 # Credits:
  11 # Alexander Nyberg <alexn@telia.com>
  12 # V Srivatsa <vatsa@in.ibm.com>
  13 # Maneesh Soni <maneesh@in.ibm.com>
  14 #
  15
  16 define bttnobp
  17         set $tasks_off=((size_t)&((struct task_struct *)0)->tasks)
  18         set $pid_off=((size_t)&((struct task_struct *)0)->pids[1].pid_list.next)
  19         set $init_t=&init_task
  20         set $next_t=(((char *)($init_t->tasks).next) - $tasks_off)
  21         while ($next_t != $init_t)
  22                 set $next_t=(struct task_struct *)$next_t
  23                 printf "\npid %d; comm %s:\n", $next_t.pid, $next_t.comm
  24                 printf "===================\n"
  25                 set var $stackp = $next_t.thread.esp
  26                 set var $stack_top = ($stackp & ~4095) + 4096
  27
  28                 while ($stackp < $stack_top)
  29                         if (*($stackp) > _stext && *($stackp) < _sinittext)
  30                                 info symbol *($stackp)
  31                         end
  32                         set $stackp += 4
  33                 end
  34                 set $next_th=(((char *)$next_t->pids[1].pid_list.next) - $pid_off)
  35                 while ($next_th != $next_t)
  36                         set $next_th=(struct task_struct *)$next_th
  37                         printf "\npid %d; comm %s:\n", $next_t.pid, $next_t.comm
  38                         printf "===================\n"
  39                         set var $stackp = $next_t.thread.esp
  40                         set var $stack_top = ($stackp & ~4095) + 4096
  41
  42                         while ($stackp < $stack_top)
  43                                 if (*($stackp) > _stext && *($stackp) < _sinittext)
  44                                         info symbol *($stackp)
  45                                 end
  46                                 set $stackp += 4
  47                         end
  48                         set $next_th=(((char *)$next_th->pids[1].pid_list.next) - $pid_off)
  49                 end
  50                 set $next_t=(char *)($next_t->tasks.next) - $tasks_off
  51         end
  52 end
  53 document bttnobp
  54         dump all thread stack traces on a kernel compiled with !CONFIG_FRAME_POINTER
  55 end
  56
  57 define btt
  58         set $tasks_off=((size_t)&((struct task_struct *)0)->tasks)
  59         set $pid_off=((size_t)&((struct task_struct *)0)->pids[1].pid_list.next)
  60         set $init_t=&init_task
  61         set $next_t=(((char *)($init_t->tasks).next) - $tasks_off)
  62         while ($next_t != $init_t)
  63                 set $next_t=(struct task_struct *)$next_t
  64                 printf "\npid %d; comm %s:\n", $next_t.pid, $next_t.comm
  65                 printf "===================\n"
  66                 set var $stackp = $next_t.thread.esp
  67                 set var $stack_top = ($stackp & ~4095) + 4096
  68                 set var $stack_bot = ($stackp & ~4095)
  69
  70                 set $stackp = *($stackp)
  71                 while (($stackp < $stack_top) && ($stackp > $stack_bot))
  72                         set var $addr = *($stackp + 4)
  73                         info symbol $addr
  74                         set $stackp = *($stackp)
  75                 end
  76
  77                 set $next_th=(((char *)$next_t->pids[1].pid_list.next) - $pid_off)
  78                 while ($next_th != $next_t)
  79                         set $next_th=(struct task_struct *)$next_th
  80                         printf "\npid %d; comm %s:\n", $next_t.pid, $next_t.comm
  81                         printf "===================\n"
  82                         set var $stackp = $next_t.thread.esp
  83                         set var $stack_top = ($stackp & ~4095) + 4096
  84                         set var $stack_bot = ($stackp & ~4095)
  85
  86                         set $stackp = *($stackp)
  87                         while (($stackp < $stack_top) && ($stackp > $stack_bot))
  88                                 set var $addr = *($stackp + 4)
  89                                 info symbol $addr
  90                                 set $stackp = *($stackp)
  91                         end
  92                         set $next_th=(((char *)$next_th->pids[1].pid_list.next) - $pid_off)
  93                 end
  94                 set $next_t=(char *)($next_t->tasks.next) - $tasks_off
  95         end
  96 end
  97 document btt
  98         dump all thread stack traces on a kernel compiled with CONFIG_FRAME_POINTER
  99 end
 100
 101 define btpid
 102         set var $pid = $arg0
 103         set $tasks_off=((size_t)&((struct task_struct *)0)->tasks)
 104         set $pid_off=((size_t)&((struct task_struct *)0)->pids[1].pid_list.next)
 105         set $init_t=&init_task
 106         set $next_t=(((char *)($init_t->tasks).next) - $tasks_off)
 107         set var $pid_task = 0
 108
 109         while ($next_t != $init_t)
 110                 set $next_t=(struct task_struct *)$next_t
 111
 112                 if ($next_t.pid == $pid)
 113                         set $pid_task = $next_t
 114                 end
 115
 116                 set $next_th=(((char *)$next_t->pids[1].pid_list.next) - $pid_off)
 117                 while ($next_th != $next_t)
 118                         set $next_th=(struct task_struct *)$next_th
 119                         if ($next_th.pid == $pid)
 120                                 set $pid_task = $next_th
 121                         end
 122                         set $next_th=(((char *)$next_th->pids[1].pid_list.next) - $pid_off)
 123                 end
 124                 set $next_t=(char *)($next_t->tasks.next) - $tasks_off
 125         end
 126
 127         printf "\npid %d; comm %s:\n", $pid_task.pid, $pid_task.comm
 128         printf "===================\n"
 129         set var $stackp = $pid_task.thread.esp
 130         set var $stack_top = ($stackp & ~4095) + 4096
 131         set var $stack_bot = ($stackp & ~4095)
 132
 133         set $stackp = *($stackp)
 134         while (($stackp < $stack_top) && ($stackp > $stack_bot))
 135                 set var $addr = *($stackp + 4)
 136                 info symbol $addr
 137                 set $stackp = *($stackp)
 138         end
 139 end
 140 document btpid
 141         backtrace of pid
 142 end
 143
 144
 145 define trapinfo
 146         set var $pid = $arg0
 147         set $tasks_off=((size_t)&((struct task_struct *)0)->tasks)
 148         set $pid_off=((size_t)&((struct task_struct *)0)->pids[1].pid_list.next)
 149         set $init_t=&init_task
 150         set $next_t=(((char *)($init_t->tasks).next) - $tasks_off)
 151         set var $pid_task = 0
 152
 153         while ($next_t != $init_t)
 154                 set $next_t=(struct task_struct *)$next_t
 155
 156                 if ($next_t.pid == $pid)
 157                         set $pid_task = $next_t
 158                 end
 159
 160                 set $next_th=(((char *)$next_t->pids[1].pid_list.next) - $pid_off)
 161                 while ($next_th != $next_t)
 162                         set $next_th=(struct task_struct *)$next_th
 163                         if ($next_th.pid == $pid)
 164                                 set $pid_task = $next_th
 165                         end
 166                         set $next_th=(((char *)$next_th->pids[1].pid_list.next) - $pid_off)
 167                 end
 168                 set $next_t=(char *)($next_t->tasks.next) - $tasks_off
 169         end
 170
 171         printf "Trapno %ld, cr2 0x%lx, error_code %ld\n", $pid_task.thread.trap_no, \
 172                                 $pid_task.thread.cr2, $pid_task.thread.error_code
 173
 174 end
 175 document trapinfo
 176         Run info threads and lookup pid of thread #1
 177         'trapinfo <pid>' will tell you by which trap & possibly
 178         addresthe kernel paniced.
 179 end
 180
 181
 182 define dmesg
 183         set $i = 0
 184         set $end_idx = (log_end - 1) & (log_buf_len - 1)
 185
 186         while ($i < logged_chars)
 187                 set $idx = (log_end - 1 - logged_chars + $i) & (log_buf_len - 1)
 188
 189                 if ($idx + 100 <= $end_idx) || \
 190                    ($end_idx <= $idx && $idx + 100 < log_buf_len)
 191                         printf "%.100s", &log_buf[$idx]
 192                         set $i = $i + 100
 193                 else
 194                         printf "%c", log_buf[$idx]
 195                         set $i = $i + 1
 196                 end
 197         end
 198 end
 199 document dmesg
 200         print the kernel ring buffer
 201 end