Documentation/admin-guide/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 define dump_log_idx
 174         set $idx = $arg0
 175         if ($argc > 1)
 176                 set $prev_flags = $arg1
 177         else
 178                 set $prev_flags = 0
 179         end
 180         set $msg = ((struct printk_log *) (log_buf + $idx))
 181         set $prefix = 1
 182         set $newline = 1
 183         set $log = log_buf + $idx + sizeof(*$msg)
 184
 185         # prev & LOG_CONT && !(msg->flags & LOG_PREIX)
 186         if (($prev_flags & 8) && !($msg->flags & 4))
 187                 set $prefix = 0
 188         end
 189
 190         # msg->flags & LOG_CONT
 191         if ($msg->flags & 8)
 192                 # (prev & LOG_CONT && !(prev & LOG_NEWLINE))
 193                 if (($prev_flags & 8) && !($prev_flags & 2))
 194                         set $prefix = 0
 195                 end
 196                 # (!(msg->flags & LOG_NEWLINE))
 197                 if (!($msg->flags & 2))
 198                         set $newline = 0
 199                 end
 200         end
 201
 202         if ($prefix)
 203                 printf "[%5lu.%06lu] ", $msg->ts_nsec / 1000000000, $msg->ts_nsec % 1000000000
 204         end
 205         if ($msg->text_len != 0)
 206                 eval "printf \"%%%d.%ds\", $log", $msg->text_len, $msg->text_len
 207         end
 208         if ($newline)
 209                 printf "\n"
 210         end
 211         if ($msg->dict_len > 0)
 212                 set $dict = $log + $msg->text_len
 213                 set $idx = 0
 214                 set $line = 1
 215                 while ($idx < $msg->dict_len)
 216                         if ($line)
 217                                 printf " "
 218                                 set $line = 0
 219                         end
 220                         set $c = $dict[$idx]
 221                         if ($c == '\0')
 222                                 printf "\n"
 223                                 set $line = 1
 224                         else
 225                                 if ($c < ' ' || $c >= 127 || $c == '\\')
 226                                         printf "\\x%02x", $c
 227                                 else
 228                                         printf "%c", $c
 229                                 end
 230                         end
 231                         set $idx = $idx + 1
 232                 end
 233                 printf "\n"
 234         end
 235 end
 236 document dump_log_idx
 237         Dump a single log given its index in the log buffer.  The first
 238         parameter is the index into log_buf, the second is optional and
 239         specified the previous log buffer's flags, used for properly
 240         formatting continued lines.
 241 end
 242
 243 define dmesg
 244         set $i = log_first_idx
 245         set $end_idx = log_first_idx
 246         set $prev_flags = 0
 247
 248         while (1)
 249                 set $msg = ((struct printk_log *) (log_buf + $i))
 250                 if ($msg->len == 0)
 251                         set $i = 0
 252                 else
 253                         dump_log_idx $i $prev_flags
 254                         set $i = $i + $msg->len
 255                         set $prev_flags = $msg->flags
 256                 end
 257                 if ($i == $end_idx)
 258                         loop_break
 259                 end
 260         end
 261 end
 262 document dmesg
 263         print the kernel ring buffer
 264 end