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

From: Corey Minyard
Date: Mon May 09 2016 - 08:11:23 EST

Next message: Felipe Balbi: "Re: [PATCH] usb: dwc3: add DWC3_GUCTL1 reg for debug"
Previous message: Peter Ujfalusi: "Re: [PATCH v2 4/5] ARM: dts: omap5: describe control for ckobuffer"
In reply to: Baoquan He: "Re: [PATCH] kdump: Fix gdb macros work work with newer and 64-bit kernels"
Next in thread: Baoquan He: "Re: [PATCH] kdump: Fix gdb macros work work with newer and 64-bit kernels"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

On 05/09/2016 12:18 AM, Baoquan He wrote:

Hi Corey,

I am trying to review this patch now, and these fixes contained are very
great. Just several concerns are added in inline comment.

By the way, did you run this in your side?

Yes, I tested on x86, x86_64, ARM and MIPS.

Comments inline...

Hi Vivek,

Member variable was added into task_struct in below commit replacing
pids[PIDTYPE_TGID], and from then on nobody complained about it. Seems
people rarely use this utility.

commit 47e65328a7b1cdfc4e3102e50d60faf94ebba7d3
Author: Oleg Nesterov <oleg@xxxxxxxxxx>
Date: Tue Mar 28 16:11:25 2006 -0800

[PATCH] pids: kill PIDTYPE_TGID

On 04/27/16 at 07:21am, Corey Minyard wrote:

Any comments on this? If no one else cares I'd be willing to take over
maintenance of this.

-corey

On 02/25/2016 07:51 AM, minyard@xxxxxxx wrote:

From: Corey Minyard <cminyard@xxxxxxxxxx>

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 <cminyard@xxxxxxxxxx>
---
Documentation/kdump/gdbmacros.txt | 90 +++++++++++++++++----------------------
1 file changed, 40 insertions(+), 50 deletions(-)

I sent this earlier, but I didn't get a response. These are clearly
wrong. I'd be happy to take over maintenance of these macros. It
might be better to move them someplace else, too, since they are also
useful for kgdb.

diff --git a/Documentation/kdump/gdbmacros.txt b/Documentation/kdump/gdbmacros.txt
index 9b9b454..e5bbd8d 100644
--- a/Documentation/kdump/gdbmacros.txt
+++ b/Documentation/kdump/gdbmacros.txt
@@ -15,14 +15,14 @@
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)

This is a quite nice fix.

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 $stackp = $next_t.thread.sp
set var $stack_top = ($stackp & ~4095) + 4096
while ($stackp < $stack_top)
@@ -31,12 +31,12 @@ 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 $stackp = $next_t.thread.sp
set var $stack_top = ($stackp & ~4095) + 4096
while ($stackp < $stack_top)
@@ -45,7 +45,7 @@ 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 +54,43 @@ document bttnobp
dump all thread stack traces on a kernel compiled with !CONFIG_FRAME_POINTER
end
+define btthreadstruct

This is a nice wrapping, but I guess you want to name it as
btthreadstack, right? Since I didn't get at all why it's related to
thread_struct except of getting 'sp'.

The name is based on what is passed into the function. You do a backtrace when given a thread structure. In my experience it is best to name functions based upon how the function's user sees it. Though I'm not stuck on the name, if you would prefer 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 $stack_top = ($stackp & ~4095) + 4096
+ set var $stack_bot = ($stackp & ~4095)
+
+ 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 btthreadstruct
+ 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)
+ btthreadstruct $next_t
- 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)
+ 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)
+ btthreadstruct $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 +102,7 @@ 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 +114,18 @@ 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
+ btthreadstruct $pid_task
end
document btpid
backtrace of pid
@@ -145,7 +135,7 @@ 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 +147,13 @@ 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

Next message: Felipe Balbi: "Re: [PATCH] usb: dwc3: add DWC3_GUCTL1 reg for debug"
Previous message: Peter Ujfalusi: "Re: [PATCH v2 4/5] ARM: dts: omap5: describe control for ckobuffer"
In reply to: Baoquan He: "Re: [PATCH] kdump: Fix gdb macros work work with newer and 64-bit kernels"
Next in thread: Baoquan He: "Re: [PATCH] kdump: Fix gdb macros work work with newer and 64-bit kernels"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]