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 #
 # This file contains a few gdb macros (user defined commands) to extract
 # useful information from kernel crashdump (kdump) like stack traces of
 # all the processes or a particular process and trapinfo.
 #
 # These macros can be used by copying this file in .gdbinit (put in home
 # directory or current directory) or by invoking gdb command with
 # --command=<command-file-name> option
 #
 # Credits:
 # Alexander Nyberg <alexn@telia.com>
 # V Srivatsa <vatsa@in.ibm.com>
 # Maneesh Soni <maneesh@in.ibm.com>
 #
 
 define bttnobp
         set $tasks_off=((size_t)&((struct task_struct *)0)->tasks)
         set $pid_off=((size_t)&((struct task_struct *)0)->thread_group.next)
         set $init_t=&init_task
         set $next_t=(((char *)($init_t->tasks).next) - $tasks_off)
         set var $stacksize = sizeof(union thread_union)
         while ($next_t != $init_t)
                 set $next_t=(struct task_struct *)$next_t
                 printf "\npid %d; comm %s:\n", $next_t.pid, $next_t.comm
                 printf "===================\n"
                 set var $stackp = $next_t.thread.sp
                 set var $stack_top = ($stackp & ~($stacksize - 1)) + $stacksize
 
                 while ($stackp < $stack_top)
                         if (*($stackp) > _stext && *($stackp) < _sinittext)
                                 info symbol *($stackp)
                         end
                         set $stackp += 4
                 end
                 set $next_th=(((char *)$next_t->thread_group.next) - $pid_off)
                 while ($next_th != $next_t)
                         set $next_th=(struct task_struct *)$next_th
                         printf "\npid %d; comm %s:\n", $next_t.pid, $next_t.comm
                         printf "===================\n"
                         set var $stackp = $next_t.thread.sp
                         set var $stack_top = ($stackp & ~($stacksize - 1)) + stacksize
 
                         while ($stackp < $stack_top)
                                 if (*($stackp) > _stext && *($stackp) < _sinittext)
                                         info symbol *($stackp)
                                 end
                                 set $stackp += 4
                         end
                         set $next_th=(((char *)$next_th->thread_group.next) - $pid_off)
                 end
                 set $next_t=(char *)($next_t->tasks.next) - $tasks_off
         end
 end
 document bttnobp
         dump all thread stack traces on a kernel compiled with !CONFIG_FRAME_POINTER
 end
 
 define btthreadstack
         set var $pid_task = $arg0
 
         printf "\npid %d; comm %s:\n", $pid_task.pid, $pid_task.comm
         printf "task struct: "
         print $pid_task
         printf "===================\n"
         set var $stackp = $pid_task.thread.sp
         set var $stacksize = sizeof(union thread_union)
         set var $stack_top = ($stackp & ~($stacksize - 1)) + $stacksize
         set var $stack_bot = ($stackp & ~($stacksize - 1))
 
         set $stackp = *((unsigned long *) $stackp)
         while (($stackp < $stack_top) && ($stackp > $stack_bot))
                 set var $addr = *(((unsigned long *) $stackp) + 1)
                 info symbol $addr
                 set $stackp = *((unsigned long *) $stackp)
         end
 end
 document btthreadstack
          dump a thread stack using the given task structure pointer
 end
 
 
 define btt
         set $tasks_off=((size_t)&((struct task_struct *)0)->tasks)
         set $pid_off=((size_t)&((struct task_struct *)0)->thread_group.next)
         set $init_t=&init_task
         set $next_t=(((char *)($init_t->tasks).next) - $tasks_off)
         while ($next_t != $init_t)
                 set $next_t=(struct task_struct *)$next_t
                 btthreadstack $next_t
 
                 set $next_th=(((char *)$next_t->thread_group.next) - $pid_off)
                 while ($next_th != $next_t)
                         set $next_th=(struct task_struct *)$next_th
                         btthreadstack $next_th
                         set $next_th=(((char *)$next_th->thread_group.next) - $pid_off)
                 end
                 set $next_t=(char *)($next_t->tasks.next) - $tasks_off
         end
 end
 document btt
         dump all thread stack traces on a kernel compiled with CONFIG_FRAME_POINTER
 end
 
 define btpid
         set var $pid = $arg0
         set $tasks_off=((size_t)&((struct task_struct *)0)->tasks)
         set $pid_off=((size_t)&((struct task_struct *)0)->thread_group.next)
         set $init_t=&init_task
         set $next_t=(((char *)($init_t->tasks).next) - $tasks_off)
         set var $pid_task = 0
 
         while ($next_t != $init_t)
                 set $next_t=(struct task_struct *)$next_t
 
                 if ($next_t.pid == $pid)
                         set $pid_task = $next_t
                 end
 
                 set $next_th=(((char *)$next_t->thread_group.next) - $pid_off)
                 while ($next_th != $next_t)
                         set $next_th=(struct task_struct *)$next_th
                         if ($next_th.pid == $pid)
                                 set $pid_task = $next_th
                         end
                         set $next_th=(((char *)$next_th->thread_group.next) - $pid_off)
                 end
                 set $next_t=(char *)($next_t->tasks.next) - $tasks_off
         end
 
         btthreadstack $pid_task
 end
 document btpid
         backtrace of pid
 end
 
 
 define trapinfo
         set var $pid = $arg0
         set $tasks_off=((size_t)&((struct task_struct *)0)->tasks)
         set $pid_off=((size_t)&((struct task_struct *)0)->thread_group.next)
         set $init_t=&init_task
         set $next_t=(((char *)($init_t->tasks).next) - $tasks_off)
         set var $pid_task = 0
 
         while ($next_t != $init_t)
                 set $next_t=(struct task_struct *)$next_t
 
                 if ($next_t.pid == $pid)
                         set $pid_task = $next_t
                 end
 
                 set $next_th=(((char *)$next_t->thread_group.next) - $pid_off)
                 while ($next_th != $next_t)
                         set $next_th=(struct task_struct *)$next_th
                         if ($next_th.pid == $pid)
                                 set $pid_task = $next_th
                         end
                         set $next_th=(((char *)$next_th->thread_group.next) - $pid_off)
                 end
                 set $next_t=(char *)($next_t->tasks.next) - $tasks_off
         end
 
         printf "Trapno %ld, cr2 0x%lx, error_code %ld\n", $pid_task.thread.trap_no, \
                                 $pid_task.thread.cr2, $pid_task.thread.error_code
 
 end
 document trapinfo
         Run info threads and lookup pid of thread #1
         'trapinfo <pid>' will tell you by which trap & possibly
         address the kernel panicked.
 end
 
 define dump_record
         set var $desc = $arg0
         set var $info = $arg1
         if ($argc > 2)
                 set var $prev_flags = $arg2
         else
                 set var $prev_flags = 0
         end
 
         set var $prefix = 1
         set var $newline = 1
 
         set var $begin = $desc->text_blk_lpos.begin % (1U << prb->text_data_ring.size_bits)
         set var $next = $desc->text_blk_lpos.next % (1U << prb->text_data_ring.size_bits)
 
         # handle data-less record
         if ($begin & 1)
                 set var $text_len = 0
                 set var $log = ""
         else
                 # handle wrapping data block
                 if ($begin > $next)
                         set var $begin = 0
                 end
 
                 # skip over descriptor id
                 set var $begin = $begin + sizeof(long)
 
                 # handle truncated message
                 if ($next - $begin < $info->text_len)
                         set var $text_len = $next - $begin
                 else
                         set var $text_len = $info->text_len
                 end
 
                 set var $log = &prb->text_data_ring.data[$begin]
         end
 
         # prev & LOG_CONT && !(info->flags & LOG_PREIX)
         if (($prev_flags & 8) && !($info->flags & 4))
                 set var $prefix = 0
         end
 
         # info->flags & LOG_CONT
         if ($info->flags & 8)
                 # (prev & LOG_CONT && !(prev & LOG_NEWLINE))
                 if (($prev_flags & 8) && !($prev_flags & 2))
                         set var $prefix = 0
                 end
                 # (!(info->flags & LOG_NEWLINE))
                 if (!($info->flags & 2))
                         set var $newline = 0
                 end
         end
 
         if ($prefix)
                 printf "[%5lu.%06lu] ", $info->ts_nsec / 1000000000, $info->ts_nsec % 1000000000
         end
         if ($text_len)
                 eval "printf \"%%%d.%ds\", $log", $text_len, $text_len
         end
         if ($newline)
                 printf "\n"
         end
 
         # handle dictionary data
 
         set var $dict = &$info->dev_info.subsystem[0]
         set var $dict_len = sizeof($info->dev_info.subsystem)
         if ($dict[0] != '\0')
                 printf " SUBSYSTEM="
                 set var $idx = 0
                 while ($idx < $dict_len)
                         set var $c = $dict[$idx]
                         if ($c == '\0')
                                 loop_break
                         else
                                 if ($c < ' ' || $c >= 127 || $c == '\\')
                                         printf "\\x%02x", $c
                                 else
                                         printf "%c", $c
                                 end
                         end
                         set var $idx = $idx + 1
                 end
                 printf "\n"
         end
 
         set var $dict = &$info->dev_info.device[0]
         set var $dict_len = sizeof($info->dev_info.device)
         if ($dict[0] != '\0')
                 printf " DEVICE="
                 set var $idx = 0
                 while ($idx < $dict_len)
                         set var $c = $dict[$idx]
                         if ($c == '\0')
                                 loop_break
                         else
                                 if ($c < ' ' || $c >= 127 || $c == '\\')
                                         printf "\\x%02x", $c
                                 else
                                         printf "%c", $c
                                 end
                         end
                         set var $idx = $idx + 1
                 end
                 printf "\n"
         end
 end
 document dump_record
         Dump a single record. The first parameter is the descriptor,
         the second parameter is the info, the third parameter is
         optional and specifies the previous record's flags, used for
         properly formatting continued lines.
 end
 
 define dmesg
         # definitions from kernel/printk/printk_ringbuffer.h
         set var $desc_committed = 1
         set var $desc_finalized = 2
         set var $desc_sv_bits = sizeof(long) * 8
         set var $desc_flags_shift = $desc_sv_bits - 2
         set var $desc_flags_mask = 3 << $desc_flags_shift
         set var $id_mask = ~$desc_flags_mask
 
         set var $desc_count = 1U << prb->desc_ring.count_bits
         set var $prev_flags = 0
 
         set var $id = prb->desc_ring.tail_id.counter
         set var $end_id = prb->desc_ring.head_id.counter
 
         while (1)
                 set var $desc = &prb->desc_ring.descs[$id % $desc_count]
                 set var $info = &prb->desc_ring.infos[$id % $desc_count]
 
                 # skip non-committed record
                 set var $state = 3 & ($desc->state_var.counter >> $desc_flags_shift)
                 if ($state == $desc_committed || $state == $desc_finalized)
                         dump_record $desc $info $prev_flags
                         set var $prev_flags = $info->flags
                 end
 
                 set var $id = ($id + 1) & $id_mask
                 if ($id == $end_id)
                         loop_break
                 end
         end
 end
 document dmesg
         print the kernel ring buffer
 end

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