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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_log_idx
set $idx = $arg0
if ($argc > 1)
set $prev_flags = $arg1
else
set $prev_flags = 0
end
set $msg = ((struct printk_log *) (log_buf + $idx))
set $prefix = 1
set $newline = 1
set $log = log_buf + $idx + sizeof(*$msg)
# prev & LOG_CONT && !(msg->flags & LOG_PREIX)
if (($prev_flags & 8) && !($msg->flags & 4))
set $prefix = 0
end
# msg->flags & LOG_CONT
if ($msg->flags & 8)
# (prev & LOG_CONT && !(prev & LOG_NEWLINE))
if (($prev_flags & 8) && !($prev_flags & 2))
set $prefix = 0
end
# (!(msg->flags & LOG_NEWLINE))
if (!($msg->flags & 2))
set $newline = 0
end
end
if ($prefix)
printf "[%5lu.%06lu] ", $msg->ts_nsec / 1000000000, $msg->ts_nsec % 1000000000
end
if ($msg->text_len != 0)
eval "printf \"%%%d.%ds\", $log", $msg->text_len, $msg->text_len
end
if ($newline)
printf "\n"
end
if ($msg->dict_len > 0)
set $dict = $log + $msg->text_len
set $idx = 0
set $line = 1
while ($idx < $msg->dict_len)
if ($line)
printf " "
set $line = 0
end
set $c = $dict[$idx]
if ($c == '\0')
printf "\n"
set $line = 1
else
if ($c < ' ' || $c >= 127 || $c == '\\')
printf "\\x%02x", $c
else
printf "%c", $c
end
end
set $idx = $idx + 1
end
printf "\n"
end
end
document dump_log_idx
Dump a single log given its index in the log buffer. The first
parameter is the index into log_buf, the second is optional and
specified the previous log buffer's flags, used for properly
formatting continued lines.
end
define dmesg
set $i = log_first_idx
set $end_idx = log_first_idx
set $prev_flags = 0
while (1)
set $msg = ((struct printk_log *) (log_buf + $i))
if ($msg->len == 0)
set $i = 0
else
dump_log_idx $i $prev_flags
set $i = $i + $msg->len
set $prev_flags = $msg->flags
end
if ($i == $end_idx)
loop_break
end
end
end
document dmesg
print the kernel ring buffer
end
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