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Re: Linux Kernel GDB tracepoint module 2010-8-30 release
- From: Hui Zhu <teawater at gmail dot com>
- To: "Frank Ch. Eigler" <fche at redhat dot com>
- Cc: Steven <mqyoung at gmail dot com>, "gdb at sourceware dot org" <gdb at sourceware dot org>, linux-kernel at vger dot kernel dot org, Michael Snyder <msnyder at vmware dot com>, Marc Khouzam <marc dot khouzam at ericsson dot com>, Thiago Jung Bauermann <thiago dot bauermann at gmail dot com>
- Date: Sat, 4 Sep 2010 12:29:56 +0800
- Subject: Re: Linux Kernel GDB tracepoint module 2010-8-30 release
- References: <AANLkTimjO7sBzR55XkPB7dmZvxXqc8PS4UDsgptXVt90@mail.gmail.com> <1283504768.2100.43.camel@steven> <y0md3suzzuj.fsf@fche.csb>
Hi Frank,
Looks systemtap are very cool.
Could you talk about how it do call stack dump like following?
(gdb) trace vfs_readdir
Tracepoint 1 at 0xffffffff8113f7fc: file
/home/teawater/kernel/linux-2.6/fs/readdir.c, line 24.
(gdb) actions
Enter actions for tracepoint 1, one per line.
End with a line saying just "end".
>collect *(unsigned char *)$rsp@512
>end
(gdb) tstart
(gdb) shell ls
2 block firmware i ipc Makefile
modules.order scripts source t~ vmlinux
a.out crypto fs include kernel mm
Module.symvers security System.map usr vmlinux.o
arch drivers gdb.txt init lib modules.builtin net
sound t virt
(gdb) tstop
(gdb) tfind
Found trace frame 0, tracepoint 1
#0 0xffffffff8113f7fd in vfs_readdir (file=0xffff880075f00780,
filler=0xffffffff8113f630 <filldir>, buf=0xffff880005785f38)
at /home/teawater/kernel/linux-2.6/fs/readdir.c:24
24 {
(gdb) bt
#0 0xffffffff8113f7fd in vfs_readdir (file=0xffff880075f00780,
filler=0xffffffff8113f630 <filldir>, buf=0xffff880005785f38)
at /home/teawater/kernel/linux-2.6/fs/readdir.c:24
#1 0xffffffff8113fa14 in sys_getdents (fd=<value optimized out>,
dirent=0x801108, count=32768)
at /home/teawater/kernel/linux-2.6/fs/readdir.c:214
#2 0xffffffff8100af42 in ?? () at
/home/teawater/kernel/linux-2.6/arch/x86/kernel/entry_64.S:487
BTW, I was not find out which ARCH of the systemtap support in its
website? It support all the arch that kprobe support?
Thanks,
Hui
On Fri, Sep 3, 2010 at 22:05, Frank Ch. Eigler <fche@redhat.com> wrote:
>
> Steven <mqyoung@gmail.com> writes:
>
>> [...]
>> ? ? ? ? (gdb) trace vfs_readdir
>> ? ? ? ? Tracepoint 3 at 0xc1175690: file fs/readdir.c, line 23.
>> ? ? ? ? (gdb) actions
>> ? ? ? ? Enter actions for tracepoint 3, one per line.
>> ? ? ? ? End with a line saying just "end".
>> ? ? ? ? > collect jiffies_64
>> ? ? ? ? > collect *file
>> ? ? ? ? > end
>
> By the way, the systemtap equivalent would be:
>
> #! /usr/bin/stap -g
> probe kernel.function("vfs_readdir") {
> ? ? ?println(%{ jiffies_64 %})
> ? ? ?println($file$)
> }
>
>
>> 2) I can not collect local variable, despite I rebuild the kernel with
>> -O0 optimization option. what is the problem? Many thanks
>> ? ? ? ? -------------------------------------------------------------------
>> ? ? ? ? (gdb) trace fs/readdir.c:29
>> ? ? ? ? Tracepoint 2 at 0xc11756ca: file fs/readdir.c, line 29.
>> ? ? ? ? (gdb) actions
>> ? ? ? ? Enter actions for tracepoint 2, one per line.
>> ? ? ? ? End with a line saying just "end".
>> ? ? ? ? > collect res
>> ? ? ? ? > end
>
>
> #! /usr/bin/stap
> probe kernel.statement("*@fs/readdir.c:29") {
> ? ? ?println($res)
> }
>
>
> - FChE
>