Messages in this thread |  | | | From | Hui Zhu <> | | Date | Thu, 12 Aug 2010 09:37:06 +0800 | | Subject | Re: Linux Kernel GDB tracepoint module demo release |
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KGTP use Kprobes, I think it can work with most part of kernel.
Thanks, Hui
On Thu, Aug 12, 2010 at 05:10, Michael Snyder <msnyder@vmware.com> wrote: > Actually, this is kind of interesting. > Can your system set a tracepoint at any arbitrary location in the > kernel? If so, I think that makes it more powerful than existing > systems such as LTTng, which can only trace statically pre-determined > locations. > > Hui Zhu wrote: >> >> Hi, >> >> GDB Tracepoint >> (http://sourceware.org/gdb/current/onlinedocs/gdb/Tracepoints.html) >> is new feature that make GDB can debug real-time program. >> I think this feature is very fit for debug Linux Kernel. So I make a >> lkm to make kernel support it. You can get it in >> https://code.google.com/p/kgtp/ >> >> I just release the demo for it. It just support collect $reg in >> x86_32. I will add the other tracepoint support in the future. >> >> For example: >> tar vxjf gtp_20100811.tar.bz2 >> cd gtp >> make >> insmod gtp.ko >> gdb ./vmlinux >> GNU gdb (GDB) 7.2.50.20100720-cvs >> Copyright (C) 2010 Free Software Foundation, Inc. >> License GPLv3+: GNU GPL version 3 or later >> <http://gnu.org/licenses/gpl.html> >> This is free software: you are free to change and redistribute it. >> There is NO WARRANTY, to the extent permitted by law. Type "show copying" >> and "show warranty" for details. >> This GDB was configured as "i686-pc-linux-gnu". >> For bug reporting instructions, please see: >> <http://www.gnu.org/software/gdb/bugs/>... >> Reading symbols from /vmlinux...done. >> (gdb) target remote /proc/gtp >> Remote debugging using /proc/gtp >> 0x00000000 in ?? () >> (gdb) trace vfs_readdir >> Tracepoint 1 at 0xc01a1ac0: file >> /home/teawater/kernel/linux-2.6/fs/readdir.c, line 23. >> (gdb) actions >> Enter actions for tracepoint 1, one per line. >> End with a line saying just "end". >>> >>> collect $reg >>> end >> >> (gdb) tstart >> (gdb) shell ls >> (gdb) tstop >> (gdb) tfind >> Found trace frame 0, tracepoint 1 >> #0 0xc01a1ac1 in vfs_readdir (file=0xc5528d00, filler=0xc01a1900 >> <filldir64>, >> buf=0xc0d09f90) at /home/teawater/kernel/linux-2.6/fs/readdir.c:23 >> 23 /home/teawater/kernel/linux-2.6/fs/readdir.c: No such file or >> directory. >> in /home/teawater/kernel/linux-2.6/fs/readdir.c >> (gdb) info reg >> eax 0xc5528d00 -984445696 >> ecx 0xc0d09f90 -1060069488 >> edx 0xc01a1900 -1072031488 >> ebx 0xfffffff7 -9 >> esp 0xc0d09f8c 0xc0d09f8c >> ebp 0x0 0x0 >> esi 0x8061480 134616192 >> edi 0xc5528d00 -984445696 >> eip 0xc01a1ac1 0xc01a1ac1 <vfs_readdir+1> >> eflags 0x286 [ PF SF IF ] >> cs 0x60 96 >> ss 0x8061480 134616192 >> ds 0x7b 123 >> es 0x7b 123 >> fs 0x0 0 >> gs 0x0 0 >> (gdb) tfind >> Found trace frame 1, tracepoint 1 >> 0xc01a1ac1 23 in /home/teawater/kernel/linux-2.6/fs/readdir.c >> (gdb) info reg >> eax 0xc5528d00 -984445696 >> ecx 0xc0d09f90 -1060069488 >> edx 0xc01a1900 -1072031488 >> ebx 0xfffffff7 -9 >> esp 0xc0d09f8c 0xc0d09f8c >> ebp 0x0 0x0 >> esi 0x8061480 134616192 >> edi 0xc5528d00 -984445696 >> eip 0xc01a1ac1 0xc01a1ac1 <vfs_readdir+1> >> eflags 0x286 [ PF SF IF ] >> cs 0x60 96 >> ss 0x8061480 134616192 >> ds 0x7b 123 >> es 0x7b 123 >> fs 0x0 0 >> gs 0x0 0 >> (gdb) tfind >> Found trace frame 2, tracepoint 1 >> #0 0xc01a1ac1 in vfs_readdir (file=0xc5528300, filler=0xc01a19e0 >> <filldir>, >> buf=0xc6c2df90) at /home/teawater/kernel/linux-2.6/fs/readdir.c:23 >> 23 in /home/teawater/kernel/linux-2.6/fs/readdir.c >> (gdb) >> Found trace frame 3, tracepoint 1 >> 0xc01a1ac1 23 in /home/teawater/kernel/linux-2.6/fs/readdir.c >> (gdb) >> Target failed to find requested trace frame. >> (gdb) quit >> A debugging session is active. >> >> Inferior 1 [Remote target] will be killed. >> >> Quit anyway? (y or n) y >> >> Thanks, >> Hui > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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