> Linux Kernel GDB tracepoint module support action X and all agent
> expression except the trace state variable codes. So KGTP can support
> a lot of collect command of tracepoint in x86-64 and x86-32.
>
> To get the new KGTP please goto
http://code.google.com/p/kgtp/downloads/list
>
> To get more message about GDB tracepoint please goto
>
http://sourceware.org/gdb/current/onlinedocs/gdb/Tracepoints.html
>
> For example:
>
> make
> sudo insmod gtp.ko
> sudo gdb ./vmlinux
>
> (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
>>collect *file
>>end
> (gdb) target remote /proc/gtp
> Remote debugging using /proc/gtp
> 0x0000000000000000 in ?? ()
> (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
> #3 0x00007f3249a81765 in ?? ()
> #4 0x00000018555503f7 in ?? ()
> #5 0x0000015400000000 in ?? ()
> #6 0x0000000000bf5048 in ?? ()
> #7 0x0000000000000000 in ?? ()
> (gdb) p file
> = (struct file *) 0xffff880075f00780
> (gdb) p *file
> = {f_u = {fu_list = {next = 0xffff880075f00480, prev =
> 0xffffe8ffffc06948}, fu_rcuhead = {next = 0xffff880075f00480,
> func = 0xffffe8ffffc06948}}, f_path = {mnt = 0xffff880037d92e00,
> dentry = 0xffff8800353239c0}, f_op = 0xffffffff81622a60, f_lock = {{
> rlock = {raw_lock = {slock = 0}}}}, f_sb_list_cpu = 0, f_count =
> {counter = 2}, f_flags = 624640, f_mode = 29, f_pos = 0, f_owner = {
> lock = {raw_lock = {lock = 16777216}}, pid = 0x0, pid_type =
> PIDTYPE_PID, uid = 0, euid = 0, signum = 0}, f_cred =
> 0xffff880079b40a80,
> f_ra = {start = 0, size = 0, async_size = 0, ra_pages = 32,
> mmap_miss = 0, prev_pos = -1}, f_version = 0, f_security = 0x0,
> private_data = 0x0, f_ep_links = {next = 0xffff880075f00828, prev =
> 0xffff880075f00828}, f_mapping = 0xffff88003539d6b8}
> (gdb) tfind
> Found trace frame 1, tracepoint 1
> 0xffffffff8113f7fd 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
> #3 0x00007f3249a81765 in ?? ()
> #4 0x00000018555503f7 in ?? ()
> #5 0x0000015400000000 in ?? ()
> #6 0x0000000000bf5048 in ?? ()
> #7 0x0000000000000000 in ?? ()
> (gdb) p *file
> = {f_u = {fu_list = {next = 0xffff880075f00480, prev =
> 0xffffe8ffffc06948}, fu_rcuhead = {next = 0xffff880075f00480,
> func = 0xffffe8ffffc06948}}, f_path = {mnt = 0xffff880037d92e00,
> dentry = 0xffff8800353239c0}, f_op = 0xffffffff81622a60, f_lock = {{
> rlock = {raw_lock = {slock = 0}}}}, f_sb_list_cpu = 0, f_count =
> {counter = 2}, f_flags = 624640, f_mode = 29, f_pos = 2147483647,
> f_owner = {lock = {raw_lock = {lock = 16777216}}, pid = 0x0,
> pid_type = PIDTYPE_PID, uid = 0, euid = 0, signum = 0},
> f_cred = 0xffff880079b40a80, f_ra = {start = 0, size = 0, async_size
> = 0, ra_pages = 32, mmap_miss = 0, prev_pos = -1}, f_version = 16,
> f_security = 0x0, private_data = 0xffff8800755d5600, f_ep_links =
> {next = 0xffff880075f00828, prev = 0xffff880075f00828},
> f_mapping = 0xffff88003539d6b8}
>
