14:21 <modem> hey

14:21 <modem> I am using systemtap to alter a function control flow

14:21 <modem> so I put on hook on it and call some embeded C-code

14:21 <modem> but then I would like the systemtap probe to return

14:22 <modem> basically I am trying a new version of the function for a specific scenario, I do not want the original code to be executed at all

14:22 <modem> everytime i have an "if" match I am expecting my code to be called instead of the embeded code

14:22 <modem> do you guy can let me know how I could achieve that using systemtap ? Thanks!

14:24 <modem> I found a way to let the orig function return triggering an error path

14:24 <modem> but it is somehow hacky

14:31 <fche> modem, it certainly is somehow hacky

14:32 <fche> but lacking any way to dramatically & portably modify -control- flow, we're left with changing -data- flow so to speak

14:32 <fche> (I mean one could in theory adjust the pt_regs PC value to jump over things, but that's far more hacky)

14:34 <modem> fche: hey

14:34 <modem> ok let's do it hacky way

14:34 <modem> thx :-)

14:34 <fche> yeah. that's the way we do security band-aids too

14:36 <modem> you means patch ?

14:37 <fche> https://securityblog.redhat.com/2015/06/03/emergency-security-band-aids-with-systemtap/

14:37 <modem> hah yes

14:37 <fche> though I think by the time I presented the concept at FOSDEM last year, some ideas crystallized better

14:40 <modem> I have seen such patch recently

14:40 <modem> rh bugzilla iirc

14:41 <modem> didn't know you presented the concept previous to that, tought it was a good idee

14:41 <modem> i defintely would patch my system with systemtap instead of rebooting from time to time to give me opportunity to migrate properly without exposing meanwhile

14:41 <fche> that's the idea & attraction

14:41 <fche> it's definitely not a turn-the-crank easy operation though

14:41 <fche> harder than taking someone's patch and applying/rebooting etc.

14:42 <fche> but it's a neat puzzle

16:58 <irker778> systemtap: mcermak systemtap.git:refs/heads/mcermak/PR20333 * release-3.0-451-g0d4f1dd / tapset/linux/nd_syscalls.stp tapset/linux/sysc_lsetxattr.stp tapset/linux/syscalls.stp: PR20333/lsetxattr http://tinyurl.com/h6vcvjj

16:58 <irker778> systemtap: mcermak systemtap.git:refs/heads/mcermak/PR20333 * release-3.0-452-ge772e0a / tapset/linux/nd_syscalls.stp tapset/linux/sysc_lstat.stp tapset/linux/syscalls.stp: PR20333/lstat http://tinyurl.com/zary429

16:58 <irker778> systemtap: mcermak systemtap.git:refs/heads/mcermak/PR20333 * release-3.0-453-g2019638 / tapset/linux/nd_syscalls.stp tapset/linux/sysc_madvise.stp tapset/linux/syscalls.stp: PR20333/madvise http://tinyurl.com/jzw4q9r

16:58 <irker778> systemtap: mcermak systemtap.git:refs/heads/mcermak/PR20333 * release-3.0-454-g4d37225 / tapset/linux/nd_syscalls.stp tapset/linux/sysc_mbind.stp tapset/linux/syscalls.stp: PR20333/mbind http://tinyurl.com/ze86um5

16:58 <irker778> systemtap: mcermak systemtap.git:refs/heads/mcermak/PR20333 * release-3.0-455-g01427b7 / tapset/linux/nd_syscalls.stp tapset/linux/sysc_membarrier.stp tapset/linux/syscalls.stp: PR20333/membarrier http://tinyurl.com/zl3zhsu

17:42 <Guest56127> Hey folks, i have compiled systemtap version 3.0. Unfortunately it is not running. The compilation of generated C code fails (Pass 4). E.g. running stap -ve 'probe begin { log("hello world") exit () }' yields in an error like this http://pastebin.com/iqz3LnwK. Do you have any clue what might be wrong?

17:51 <fche> Guest56127, hi, use git systemtap for recent kernels

17:51 <fche> the 3.0 release is now many months old, and newer kernels break interfaces

17:52 <fche> a stap 3.1 release will come out in a few weeks

17:54 <Guest56127> Ok, I will clone the git repo and try again. I am using 4.7.2 is that already too recent for version 3.0?

18:04 <fche> I think so

18:05 <fche> https://sourceware.org/bugzilla/show_bug.cgi?id=19990 btw

18:18 <Guest56127> I tried with recent version. Now systemtap prints hello world but i receive some strange error about a module. Here is the error http://pastebin.com/U2r4Cw3h.

18:22 <Guest56127> Furthermore, when i run nettop.stp from https://sourceware.org/systemtap/examples/network/nettop.stp i get semantic errors like in http://pastebin.com/FkDR79ga

18:24 <Guest56127> Is there anything wrong with the installation?

18:31 <fche> hi

18:32 <fche> hm that first message, no idea, will take a deeper look

18:32 <fche> re the second message (semantic errors) - typical of missing kernel debuginfo

18:39 <Guest56127> I have compiled the kernel myself with CONFIG_DEBUG_INFO=y do i need anything in addition?

19:30 <fche> Guest56127, the stap README contains the full list of suggested CONFIG*s, but for debuginfo that's the only one really

19:35 <Guest56127> Ok, i will have a look on that README and recompile the kernel eventually.

19:35 <Guest56127> thx for your help

19:35 <fche> np, sorry it's not working for you out-of-the-box

19:35 <fche> what distro ar you running?

19:36 <Guest56127> no, certain distro i have a self compiled system with kernel 4.7.2.

19:36 <fche> yeah. a good distro takes care of such things for you, but that's not for everyone

23:17 <irker778> systemtap: lberk systemtap.git:refs/heads/master * release-3.0-322-gb82a3aa / java/HelperSDT.c: java: add basic support for java objects http://tinyurl.com/hp5zy7u