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)->thread_group.next)
  19         set $init_t=&init_task
  20         set $next_t=(((char *)($init_t->tasks).next) - $tasks_off)
  21         set var $stacksize = sizeof(union thread_union)
  22         while ($next_t != $init_t)
  23                 set $next_t=(struct task_struct *)$next_t
  24                 printf "\npid %d; comm %s:\n", $next_t.pid, $next_t.comm
  25                 printf "===================\n"
  26                 set var $stackp = $next_t.thread.sp
  27                 set var $stack_top = ($stackp & ~($stacksize - 1)) + $stacksize
  28
  29                 while ($stackp < $stack_top)
  30                         if (*($stackp) > _stext && *($stackp) < _sinittext)
  31                                 info symbol *($stackp)
  32                         end
  33                         set $stackp += 4
  34                 end
  35                 set $next_th=(((char *)$next_t->thread_group.next) - $pid_off)
  36                 while ($next_th != $next_t)
  37                         set $next_th=(struct task_struct *)$next_th
  38                         printf "\npid %d; comm %s:\n", $next_t.pid, $next_t.comm
  39                         printf "===================\n"
  40                         set var $stackp = $next_t.thread.sp
  41                         set var $stack_top = ($stackp & ~($stacksize - 1)) + stacksize
  42
  43                         while ($stackp < $stack_top)
  44                                 if (*($stackp) > _stext && *($stackp) < _sinittext)
  45                                         info symbol *($stackp)
  46                                 end
  47                                 set $stackp += 4
  48                         end
  49                         set $next_th=(((char *)$next_th->thread_group.next) - $pid_off)
  50                 end
  51                 set $next_t=(char *)($next_t->tasks.next) - $tasks_off
  52         end
  53 end
  54 document bttnobp
  55         dump all thread stack traces on a kernel compiled with !CONFIG_FRAME_POINTER
  56 end
  57
  58 define btthreadstack
  59         set var $pid_task = $arg0
  60
  61         printf "\npid %d; comm %s:\n", $pid_task.pid, $pid_task.comm
  62         printf "task struct: "
  63         print $pid_task
  64         printf "===================\n"
  65         set var $stackp = $pid_task.thread.sp
  66         set var $stacksize = sizeof(union thread_union)
  67         set var $stack_top = ($stackp & ~($stacksize - 1)) + $stacksize
  68         set var $stack_bot = ($stackp & ~($stacksize - 1))
  69
  70         set $stackp = *((unsigned long *) $stackp)
  71         while (($stackp < $stack_top) && ($stackp > $stack_bot))
  72                 set var $addr = *(((unsigned long *) $stackp) + 1)
  73                 info symbol $addr
  74                 set $stackp = *((unsigned long *) $stackp)
  75         end
  76 end
  77 document btthreadstack
  78          dump a thread stack using the given task structure pointer
  79 end
  80
  81
  82 define btt
  83         set $tasks_off=((size_t)&((struct task_struct *)0)->tasks)
  84         set $pid_off=((size_t)&((struct task_struct *)0)->thread_group.next)
  85         set $init_t=&init_task
  86         set $next_t=(((char *)($init_t->tasks).next) - $tasks_off)
  87         while ($next_t != $init_t)
  88                 set $next_t=(struct task_struct *)$next_t
  89                 btthreadstack $next_t
  90
  91                 set $next_th=(((char *)$next_t->thread_group.next) - $pid_off)
  92                 while ($next_th != $next_t)
  93                         set $next_th=(struct task_struct *)$next_th
  94                         btthreadstack $next_th
  95                         set $next_th=(((char *)$next_th->thread_group.next) - $pid_off)
  96                 end
  97                 set $next_t=(char *)($next_t->tasks.next) - $tasks_off
  98         end
  99 end
 100 document btt
 101         dump all thread stack traces on a kernel compiled with CONFIG_FRAME_POINTER
 102 end
 103
 104 define btpid
 105         set var $pid = $arg0
 106         set $tasks_off=((size_t)&((struct task_struct *)0)->tasks)
 107         set $pid_off=((size_t)&((struct task_struct *)0)->thread_group.next)
 108         set $init_t=&init_task
 109         set $next_t=(((char *)($init_t->tasks).next) - $tasks_off)
 110         set var $pid_task = 0
 111
 112         while ($next_t != $init_t)
 113                 set $next_t=(struct task_struct *)$next_t
 114
 115                 if ($next_t.pid == $pid)
 116                         set $pid_task = $next_t
 117                 end
 118
 119                 set $next_th=(((char *)$next_t->thread_group.next) - $pid_off)
 120                 while ($next_th != $next_t)
 121                         set $next_th=(struct task_struct *)$next_th
 122                         if ($next_th.pid == $pid)
 123                                 set $pid_task = $next_th
 124                         end
 125                         set $next_th=(((char *)$next_th->thread_group.next) - $pid_off)
 126                 end
 127                 set $next_t=(char *)($next_t->tasks.next) - $tasks_off
 128         end
 129
 130         btthreadstack $pid_task
 131 end
 132 document btpid
 133         backtrace of pid
 134 end
 135
 136
 137 define trapinfo
 138         set var $pid = $arg0
 139         set $tasks_off=((size_t)&((struct task_struct *)0)->tasks)
 140         set $pid_off=((size_t)&((struct task_struct *)0)->thread_group.next)
 141         set $init_t=&init_task
 142         set $next_t=(((char *)($init_t->tasks).next) - $tasks_off)
 143         set var $pid_task = 0
 144
 145         while ($next_t != $init_t)
 146                 set $next_t=(struct task_struct *)$next_t
 147
 148                 if ($next_t.pid == $pid)
 149                         set $pid_task = $next_t
 150                 end
 151
 152                 set $next_th=(((char *)$next_t->thread_group.next) - $pid_off)
 153                 while ($next_th != $next_t)
 154                         set $next_th=(struct task_struct *)$next_th
 155                         if ($next_th.pid == $pid)
 156                                 set $pid_task = $next_th
 157                         end
 158                         set $next_th=(((char *)$next_th->thread_group.next) - $pid_off)
 159                 end
 160                 set $next_t=(char *)($next_t->tasks.next) - $tasks_off
 161         end
 162
 163         printf "Trapno %ld, cr2 0x%lx, error_code %ld\n", $pid_task.thread.trap_no, \
 164                                 $pid_task.thread.cr2, $pid_task.thread.error_code
 165
 166 end
 167 document trapinfo
 168         Run info threads and lookup pid of thread #1
 169         'trapinfo <pid>' will tell you by which trap & possibly
 170         address the kernel panicked.
 171 end
 172
 173
 174 define dmesg
 175         set $i = 0
 176         set $end_idx = (log_end - 1) & (log_buf_len - 1)
 177
 178         while ($i < logged_chars)
 179                 set $idx = (log_end - 1 - logged_chars + $i) & (log_buf_len - 1)
 180
 181                 if ($idx + 100 <= $end_idx) || \
 182                    ($end_idx <= $idx && $idx + 100 < log_buf_len)
 183                         printf "%.100s", &log_buf[$idx]
 184                         set $i = $i + 100
 185                 else
 186                         printf "%c", log_buf[$idx]
 187                         set $i = $i + 1
 188                 end
 189         end
 190 end
 191 document dmesg
 192         print the kernel ring buffer
 193 end