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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 = $info->flags
+ end
+
+ if ($id == $end_id)
+ loop_break
+ end
+ set var $id = ($id + 1) & $id_mask
+ end
+end
+document dmesg
+ print the kernel ring buffer
+end