Re: [PATCH v2] kdump: Fix gdb macros work work with newer and 64-bit kernels

Corey Minyard Mon, 16 May 2016 04:53:33 -0700

On 05/16/2016 04:32 AM, Baoquan He wrote:

On 05/10/16 at 07:30pm, miny...@acm.org wrote:

From: Corey Minyard <cminy...@mvista.com>


Lots of little changes needed to be made to clean these up, remove the
four byte pointer assumption and traverse the pid queue properly.
Also consolidate the traceback code into a single function instead
of having three copies of it.

Signed-off-by: Corey Minyard <cminy...@mvista.com>

Hi Corey,

Today I tried gdbmacro.txt and found dmesg doesn't work. I tested it
on the latest 4.6.0 kernel. And I directly copy /proc/vmcore out
and use gdb to open it by below command"

gdb vmlinux /var/crash/vmcore --"gdbmacros.txt"

All macro functions work well except of dmesg since code inside refer to
the deprecated variable like "log_end" and "logged_chars". But these
have been changed since this commit:

commit 7ff9554bb578ba02166071d2d487b7fc7d860d62
Author: Kay Sievers <k...@vrfy.org>
Date:   Thu May 3 02:29:13 2012 +0200

     printk: convert byte-buffer to variable-length record buffer

So invoking dmesg will cause an error message printing out:

(gdb) dmesg
No symbol "log_end" in current context.


Yes, I was actually aware of that, but that's a different issue and I
hadn't thought about it much.

-corey

Thanks
Baoquan

---

Changes since v1:

Rename btthreadstruct to btthreadstack

Use sizeof(union thread_union) for the stack size instead of a hardcoded
4096.

  Documentation/kdump/gdbmacros.txt | 96 ++++++++++++++++++---------------------
  1 file changed, 44 insertions(+), 52 deletions(-)

diff --git a/Documentation/kdump/gdbmacros.txt 
b/Documentation/kdump/gdbmacros.txt
index 9b9b454..35f6a98 100644
--- a/Documentation/kdump/gdbmacros.txt
+++ b/Documentation/kdump/gdbmacros.txt
@@ -15,15 +15,16 @@

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 $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.esp
-               set var $stack_top = ($stackp & ~4095) + 4096
+               set var $stackp = $next_t.thread.sp
+               set var $stack_top = ($stackp & ~($stacksize - 1)) + $stacksize

while ($stackp < $stack_top)

                        if (*($stackp) > _stext && *($stackp) < _sinittext)
@@ -31,13 +32,13 @@ define bttnobp
                        end
                        set $stackp += 4
                end
-               set $next_th=(((char *)$next_t->pids[1].pid_list.next) - 
$pid_off)
+               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.esp
-                       set var $stack_top = ($stackp & ~4095) + 4096
+                       set var $stackp = $next_t.thread.sp
+                       set var $stack_top = ($stackp & ~($stacksize - 1)) + 
stacksize

while ($stackp < $stack_top)

                                if (*($stackp) > _stext && *($stackp) < 
_sinittext)
@@ -45,7 +46,7 @@ define bttnobp
                                end
                                set $stackp += 4
                        end
-                       set $next_th=(((char *)$next_th->pids[1].pid_list.next) 
- $pid_off)
+                       set $next_th=(((char *)$next_th->thread_group.next) - 
$pid_off)
                end
                set $next_t=(char *)($next_t->tasks.next) - $tasks_off
        end
@@ -54,42 +55,44 @@ 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)->pids[1].pid_list.next)
+       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
-               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
+               btthreadstack $next_t

- set $next_th=(((char *)$next_t->pids[1].pid_list.next) - $pid_off)

+               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.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)
+                       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
@@ -101,7 +104,7 @@ 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 $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
@@ -113,29 +116,18 @@ define btpid
                        set $pid_task = $next_t
                end

- set $next_th=(((char *)$next_t->pids[1].pid_list.next) - $pid_off)

+               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->pids[1].pid_list.next) 
- $pid_off)
+                       set $next_th=(((char *)$next_th->thread_group.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
+       btthreadstack $pid_task
  end
  document btpid
        backtrace of pid
@@ -145,7 +137,7 @@ 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 $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
@@ -157,13 +149,13 @@ define trapinfo
                        set $pid_task = $next_t
                end

- set $next_th=(((char *)$next_t->pids[1].pid_list.next) - $pid_off)

+               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->pids[1].pid_list.next) 
- $pid_off)
+                       set $next_th=(((char *)$next_th->thread_group.next) - 
$pid_off)
                end
                set $next_t=(char *)($next_t->tasks.next) - $tasks_off
        end
--
2.7.4


_______________________________________________
kexec mailing list
ke...@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

Re: [PATCH v2] kdump: Fix gdb macros work work with newer and 64-bit kernels

Reply via email to