Documentation/admin-guide/kdump/gdbmacros.txt - linux/torvalds/linux - Git at Google

 #
 # 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
	#
	# 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