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

Started byBaoquan He <bhe@redhat.com>
First post2016-05-16 11:40 +0200
Last post2016-05-16 14:30 +0200
Articles 4 — 2 participants

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  Re: [PATCH v2] kdump: Fix gdb macros work work with newer and 64-bit  kernels Baoquan He <bhe@redhat.com> - 2016-05-16 11:40 +0200
    Re: [PATCH v2] kdump: Fix gdb macros work work with newer and 64-bit  kernels Baoquan He <bhe@redhat.com> - 2016-05-16 11:50 +0200
    Re: [PATCH v2] kdump: Fix gdb macros work work with newer and 64-bit  kernels Corey Minyard <minyard@acm.org> - 2016-05-16 14:00 +0200
      Re: [PATCH v2] kdump: Fix gdb macros work work with newer and 64-bit  kernels Baoquan He <bhe@redhat.com> - 2016-05-16 14:30 +0200

#1401394 — Re: [PATCH v2] kdump: Fix gdb macros work work with newer and 64-bit kernels

FromBaoquan He <bhe@redhat.com>
Date2016-05-16 11:40 +0200
SubjectRe: [PATCH v2] kdump: Fix gdb macros work work with newer and 64-bit kernels
Message-ID<rznah-5ch-9@gated-at.bofh.it>
On 05/10/16 at 07:30pm, minyard@acm.org wrote:
> From: Corey Minyard <cminyard@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 <cminyard@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 <kay@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.

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
> kexec@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec

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#1401402

FromBaoquan He <bhe@redhat.com>
Date2016-05-16 11:50 +0200
Message-ID<rznjY-5fy-11@gated-at.bofh.it>
In reply to#1401394
On 05/16/16 at 05:32pm, Baoquan He wrote:
> On 05/10/16 at 07:30pm, minyard@acm.org wrote:
> > From: Corey Minyard <cminyard@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 <cminyard@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"
		Here I means  --command="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 <kay@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.
> 
> 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
> > kexec@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/kexec
> 
> _______________________________________________
> kexec mailing list
> kexec@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec

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#1401462

FromCorey Minyard <minyard@acm.org>
Date2016-05-16 14:00 +0200
Message-ID<rzplL-6AA-15@gated-at.bofh.it>
In reply to#1401394
On 05/16/2016 04:32 AM, Baoquan He wrote:
> On 05/10/16 at 07:30pm, minyard@acm.org wrote:
>> From: Corey Minyard <cminyard@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 <cminyard@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 <kay@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
>> kexec@lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/kexec

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#1401472

FromBaoquan He <bhe@redhat.com>
Date2016-05-16 14:30 +0200
Message-ID<rzpOO-71w-21@gated-at.bofh.it>
In reply to#1401462
On 05/16/16 at 06:52am, Corey Minyard wrote:
> On 05/16/2016 04:32 AM, Baoquan He wrote:
> >On 05/10/16 at 07:30pm, minyard@acm.org wrote:
> >>From: Corey Minyard <cminyard@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 <cminyard@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 <kay@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.

Got it. Then fixes covered by this patch looks good. Ack it, thanks
for this effort.

Acked-by: Baoquan He <bhe@redhat.com>

Thanks
Baoquan

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