From b089f4a68eccd9782c89262c0d7cae146d5a8a40 Mon Sep 17 00:00:00 2001 From: Vivek Goyal Date: Sat, 25 Jun 2005 14:58:15 -0700 Subject: [PATCH] kdump: Documentation for Kdump This patch contains the documentation for the kexec based crash dump tool. Quick kdump-howto ================================================================ 1) Download and build kexec-tools. 2) Download and build the latest kexec/kdump (-mm) kernel patchset. Two kernels need to be built in order to get this feature working. A) First kernel: a) Enable "kexec system call" feature: CONFIG_KEXEC=y b) Physical load address (use default): CONFIG_PHYSICAL_START=0x100000 c) Enable "sysfs file system support": CONFIG_SYSFS=y d) Boot into first kernel with the command line parameter "crashkernel=Y@X": For example: "crashkernel=64M@16M". B) Second kernel: a) Enable "kernel crash dumps" feature: CONFIG_CRASH_DUMP=y b) Physical load addreess, use same load address as X in "crashkernel" kernel parameter in d) above, e.g., 16 MB or 0x1000000. CONFIG_PHYSICAL_START=0x1000000 c) Enable "/proc/vmcore support" (Optional, in Pseudo filesystems). CONFIG_PROC_VMCORE=y 3) Boot into the first kernel. 4) Load the second kernel to be booted using: kexec -p --crash-dump --args-linux --append="root= maxcpus=1 init 1" 5) System reboots into the second kernel when a panic occurs. A module can be written to force the panic, for testing purposes. 6) See Documentation/kdump.txt for how to read the first kernel's memory image and how to analyze it. Signed-off-by: Hariprasad Nellitheertha Signed-off-by: Eric Biederman Signed-off-by: Vivek Goyal Signed-off-by: randy_dunlap Signed-off-by: Maneesh Soni Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/kdump/gdbmacros.txt | 179 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 179 insertions(+) create mode 100644 Documentation/kdump/gdbmacros.txt (limited to 'Documentation/kdump/gdbmacros.txt') diff --git a/Documentation/kdump/gdbmacros.txt b/Documentation/kdump/gdbmacros.txt new file mode 100644 index 000000000000..bc1b9eb92ae1 --- /dev/null +++ b/Documentation/kdump/gdbmacros.txt @@ -0,0 +1,179 @@ +# +# 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= option +# +# Credits: +# Alexander Nyberg +# V Srivatsa +# Maneesh Soni +# + +define bttnobp + set $tasks_off=((size_t)&((struct task_struct *)0)->tasks) + set $pid_off=((size_t)&((struct task_struct *)0)->pids[1].pid_list.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 + printf "\npid %d; comm %s:\n", $next_t.pid, $next_t.comm + printf "===================\n" + set var $stackp = $next_t.thread.esp + set var $stack_top = ($stackp & ~4095) + 4096 + + while ($stackp < $stack_top) + if (*($stackp) > _stext && *($stackp) < _sinittext) + info symbol *($stackp) + end + set $stackp += 4 + end + set $next_th=(((char *)$next_t->pids[1].pid_list.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.esp + set var $stack_top = ($stackp & ~4095) + 4096 + + while ($stackp < $stack_top) + if (*($stackp) > _stext && *($stackp) < _sinittext) + info symbol *($stackp) + end + set $stackp += 4 + end + set $next_th=(((char *)$next_th->pids[1].pid_list.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 btt + set $tasks_off=((size_t)&((struct task_struct *)0)->tasks) + set $pid_off=((size_t)&((struct task_struct *)0)->pids[1].pid_list.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 + printf "\npid %d; comm %s:\n", $next_t.pid, $next_t.comm + printf "===================\n" + set var $stackp = $next_t.thread.esp + set var $stack_top = ($stackp & ~4095) + 4096 + set var $stack_bot = ($stackp & ~4095) + + set $stackp = *($stackp) + while (($stackp < $stack_top) && ($stackp > $stack_bot)) + set var $addr = *($stackp + 4) + info symbol $addr + set $stackp = *($stackp) + end + + set $next_th=(((char *)$next_t->pids[1].pid_list.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.esp + set var $stack_top = ($stackp & ~4095) + 4096 + set var $stack_bot = ($stackp & ~4095) + + set $stackp = *($stackp) + while (($stackp < $stack_top) && ($stackp > $stack_bot)) + set var $addr = *($stackp + 4) + info symbol $addr + set $stackp = *($stackp) + end + set $next_th=(((char *)$next_th->pids[1].pid_list.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)->pids[1].pid_list.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->pids[1].pid_list.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->pids[1].pid_list.next) - $pid_off) + end + set $next_t=(char *)($next_t->tasks.next) - $tasks_off + end + + printf "\npid %d; comm %s:\n", $pid_task.pid, $pid_task.comm + printf "===================\n" + set var $stackp = $pid_task.thread.esp + set var $stack_top = ($stackp & ~4095) + 4096 + set var $stack_bot = ($stackp & ~4095) + + set $stackp = *($stackp) + while (($stackp < $stack_top) && ($stackp > $stack_bot)) + set var $addr = *($stackp + 4) + info symbol $addr + set $stackp = *($stackp) + end +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)->pids[1].pid_list.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->pids[1].pid_list.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->pids[1].pid_list.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 ' will tell you by which trap & possibly + addresthe kernel paniced. +end -- cgit