#
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# This file contains a few gdb macros (user defined commands) to extract
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# useful information from kernel crashdump (kdump) like stack traces of
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# all the processes or a particular process and trapinfo.
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#
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# These macros can be used by copying this file in .gdbinit (put in home
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# directory or current directory) or by invoking gdb command with
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# --command=<command-file-name> option
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#
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# Credits:
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# Alexander Nyberg <alexn@telia.com>
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# V Srivatsa <vatsa@in.ibm.com>
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# Maneesh Soni <maneesh@in.ibm.com>
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#
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define bttnobp
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set $tasks_off=((size_t)&((struct task_struct *)0)->tasks)
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set $pid_off=((size_t)&((struct task_struct *)0)->thread_group.next)
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set $init_t=&init_task
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set $next_t=(((char *)($init_t->tasks).next) - $tasks_off)
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set var $stacksize = sizeof(union thread_union)
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while ($next_t != $init_t)
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set $next_t=(struct task_struct *)$next_t
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printf "\npid %d; comm %s:\n", $next_t.pid, $next_t.comm
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printf "===================\n"
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set var $stackp = $next_t.thread.sp
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set var $stack_top = ($stackp & ~($stacksize - 1)) + $stacksize
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while ($stackp < $stack_top)
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if (*($stackp) > _stext && *($stackp) < _sinittext)
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info symbol *($stackp)
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end
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set $stackp += 4
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end
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set $next_th=(((char *)$next_t->thread_group.next) - $pid_off)
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while ($next_th != $next_t)
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set $next_th=(struct task_struct *)$next_th
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printf "\npid %d; comm %s:\n", $next_t.pid, $next_t.comm
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printf "===================\n"
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set var $stackp = $next_t.thread.sp
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set var $stack_top = ($stackp & ~($stacksize - 1)) + stacksize
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while ($stackp < $stack_top)
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if (*($stackp) > _stext && *($stackp) < _sinittext)
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info symbol *($stackp)
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end
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set $stackp += 4
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end
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set $next_th=(((char *)$next_th->thread_group.next) - $pid_off)
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end
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set $next_t=(char *)($next_t->tasks.next) - $tasks_off
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end
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end
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document bttnobp
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dump all thread stack traces on a kernel compiled with !CONFIG_FRAME_POINTER
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end
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define btthreadstack
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set var $pid_task = $arg0
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printf "\npid %d; comm %s:\n", $pid_task.pid, $pid_task.comm
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printf "task struct: "
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print $pid_task
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printf "===================\n"
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set var $stackp = $pid_task.thread.sp
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set var $stacksize = sizeof(union thread_union)
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set var $stack_top = ($stackp & ~($stacksize - 1)) + $stacksize
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set var $stack_bot = ($stackp & ~($stacksize - 1))
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set $stackp = *((unsigned long *) $stackp)
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while (($stackp < $stack_top) && ($stackp > $stack_bot))
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set var $addr = *(((unsigned long *) $stackp) + 1)
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info symbol $addr
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set $stackp = *((unsigned long *) $stackp)
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end
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end
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document btthreadstack
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dump a thread stack using the given task structure pointer
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end
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define btt
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set $tasks_off=((size_t)&((struct task_struct *)0)->tasks)
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set $pid_off=((size_t)&((struct task_struct *)0)->thread_group.next)
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set $init_t=&init_task
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set $next_t=(((char *)($init_t->tasks).next) - $tasks_off)
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while ($next_t != $init_t)
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set $next_t=(struct task_struct *)$next_t
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btthreadstack $next_t
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set $next_th=(((char *)$next_t->thread_group.next) - $pid_off)
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while ($next_th != $next_t)
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set $next_th=(struct task_struct *)$next_th
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btthreadstack $next_th
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set $next_th=(((char *)$next_th->thread_group.next) - $pid_off)
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end
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set $next_t=(char *)($next_t->tasks.next) - $tasks_off
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end
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end
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document btt
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dump all thread stack traces on a kernel compiled with CONFIG_FRAME_POINTER
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end
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define btpid
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set var $pid = $arg0
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set $tasks_off=((size_t)&((struct task_struct *)0)->tasks)
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set $pid_off=((size_t)&((struct task_struct *)0)->thread_group.next)
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set $init_t=&init_task
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set $next_t=(((char *)($init_t->tasks).next) - $tasks_off)
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set var $pid_task = 0
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while ($next_t != $init_t)
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set $next_t=(struct task_struct *)$next_t
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if ($next_t.pid == $pid)
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set $pid_task = $next_t
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end
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set $next_th=(((char *)$next_t->thread_group.next) - $pid_off)
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while ($next_th != $next_t)
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set $next_th=(struct task_struct *)$next_th
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if ($next_th.pid == $pid)
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set $pid_task = $next_th
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end
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set $next_th=(((char *)$next_th->thread_group.next) - $pid_off)
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end
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set $next_t=(char *)($next_t->tasks.next) - $tasks_off
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end
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btthreadstack $pid_task
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end
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document btpid
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backtrace of pid
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end
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define trapinfo
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set var $pid = $arg0
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set $tasks_off=((size_t)&((struct task_struct *)0)->tasks)
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set $pid_off=((size_t)&((struct task_struct *)0)->thread_group.next)
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set $init_t=&init_task
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set $next_t=(((char *)($init_t->tasks).next) - $tasks_off)
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set var $pid_task = 0
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while ($next_t != $init_t)
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set $next_t=(struct task_struct *)$next_t
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if ($next_t.pid == $pid)
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set $pid_task = $next_t
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end
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set $next_th=(((char *)$next_t->thread_group.next) - $pid_off)
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while ($next_th != $next_t)
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set $next_th=(struct task_struct *)$next_th
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if ($next_th.pid == $pid)
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set $pid_task = $next_th
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end
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set $next_th=(((char *)$next_th->thread_group.next) - $pid_off)
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end
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set $next_t=(char *)($next_t->tasks.next) - $tasks_off
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end
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printf "Trapno %ld, cr2 0x%lx, error_code %ld\n", $pid_task.thread.trap_no, \
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$pid_task.thread.cr2, $pid_task.thread.error_code
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end
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document trapinfo
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Run info threads and lookup pid of thread #1
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'trapinfo <pid>' will tell you by which trap & possibly
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address the kernel panicked.
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end
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define dump_log_idx
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set $idx = $arg0
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if ($argc > 1)
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set $prev_flags = $arg1
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else
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set $prev_flags = 0
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end
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set $msg = ((struct printk_log *) (log_buf + $idx))
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set $prefix = 1
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set $newline = 1
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set $log = log_buf + $idx + sizeof(*$msg)
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# prev & LOG_CONT && !(msg->flags & LOG_PREIX)
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if (($prev_flags & 8) && !($msg->flags & 4))
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set $prefix = 0
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end
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# msg->flags & LOG_CONT
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if ($msg->flags & 8)
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# (prev & LOG_CONT && !(prev & LOG_NEWLINE))
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if (($prev_flags & 8) && !($prev_flags & 2))
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set $prefix = 0
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end
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# (!(msg->flags & LOG_NEWLINE))
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if (!($msg->flags & 2))
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set $newline = 0
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end
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end
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if ($prefix)
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printf "[%5lu.%06lu] ", $msg->ts_nsec / 1000000000, $msg->ts_nsec % 1000000000
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end
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if ($msg->text_len != 0)
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eval "printf \"%%%d.%ds\", $log", $msg->text_len, $msg->text_len
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end
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if ($newline)
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printf "\n"
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end
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if ($msg->dict_len > 0)
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set $dict = $log + $msg->text_len
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set $idx = 0
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set $line = 1
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while ($idx < $msg->dict_len)
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if ($line)
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printf " "
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set $line = 0
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end
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set $c = $dict[$idx]
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if ($c == '\0')
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printf "\n"
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set $line = 1
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else
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if ($c < ' ' || $c >= 127 || $c == '\\')
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printf "\\x%02x", $c
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else
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printf "%c", $c
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end
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end
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set $idx = $idx + 1
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end
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printf "\n"
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end
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end
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document dump_log_idx
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Dump a single log given its index in the log buffer. The first
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parameter is the index into log_buf, the second is optional and
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specified the previous log buffer's flags, used for properly
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formatting continued lines.
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end
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define dmesg
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set $i = log_first_idx
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set $end_idx = log_first_idx
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set $prev_flags = 0
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while (1)
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set $msg = ((struct printk_log *) (log_buf + $i))
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if ($msg->len == 0)
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set $i = 0
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else
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dump_log_idx $i $prev_flags
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set $i = $i + $msg->len
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set $prev_flags = $msg->flags
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end
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if ($i == $end_idx)
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loop_break
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end
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end
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end
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document dmesg
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print the kernel ring buffer
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end
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