undefined system symbol error

[Josh Stone]

On 05/09/2016 04:32 AM, 冷高峰 wrote:
> After install systemtap, i run a script. And i get some error. I can't
> ensure i had upload all the info you need,  if you need more info, just let
> me know.

This looks like PR16884.  Even though you're not probing tracepoints
directly, we use them internally for process tracking to enable those
backtrace functions.  The tracepoint API changed in kernel 3.15, and we
caught up to those changes in systemtap 2.5.

https://sourceware.org/bugzilla/show_bug.cgi?id=16844

You can either file a bug with Ubuntu to backport those fixes, or
compile a newer release of systemtap yourself.

> **The script:**
> 
>     global s;
>     global quit = 0;
>     probe timer.profile {
>      if (pid() == target()) {
>          if (quit) {
>              foreach (i in s-) {
>                  print_ustack(i);
>                  printf("\t%d\n", @count(s[i]));
>              }
>              exit()
>          } else {
>              s[ubacktrace()] <<< 1;
>          }
>      }
>     }
>     probe timer.s(20) {
>      quit = 1
>     }
> 
> 
> 
> **Error Info is :**
> 
>     WARNING: "__tracepoint_sched_process_fork"
> [/tmp/stapH5cHsd/stap_958d0ff0e571c9357f1e193511d8baa3_269311.ko]undefined!
>     WARNING: "__tracepoint_sys_exit"
> [/tmp/stapH5cHsd/stap_958d0ff0e571c9357f1e193511d8baa3_269311.ko]
> undefined!
>     WARNING: "__tracepoint_sys_enter"
> [/tmp/stapH5cHsd/stap_958d0ff0e571c9357f1e193511d8baa3_269311.ko]
> undefined!
>     WARNING: "__tracepoint_sched_process_exec"
> [/tmp/stapH5cHsd/stap_958d0ff0e571c9357f1e193511d8baa3_269311.ko]
> undefined!
>     WARNING: "__tracepoint_sched_process_exit"
> [/tmp/stapH5cHsd/stap_958d0ff0e571c9357f1e193511d8baa3_269311.ko]
> undefined!
>     ERROR: Couldn't insert module
> '/tmp/stapH5cHsd/stap_958d0ff0e571c9357f1e193511d8baa3_269311.ko':
> Unknown symbol in module
>     WARNING: /usr/bin/staprun exited with status: 1
>     Pass 5: run failed.  [man error::pass5]
>     Tip: /usr/share/doc/systemtap/README.Debian should help you get started.
> 
> **Some info of my  env:**
> 
>     # cat /proc/version
>     Linux version 3.16.0-70-generic (buildd@lgw01-01) (gcc version
> 4.8.2 (Ubuntu 4.8.2-19ubuntu1) ) #90~14.04.1-Ubuntu SMP Wed Apr 6
> 22:56:34 UTC 2016
> 
>     # stap -V
>     Systemtap translator/driver (version 2.3/0.158, Debian version
> 2.3-1ubuntu1.4 (trusty))
>     Copyright (C) 2005-2013 Red Hat, Inc. and others
>     This is free software; see the source for copying conditions.
>     enabled features: AVAHI LIBSQLITE3 NSS TR1_UNORDERED_MAP NLS
> 
>     # dpkg --list | grep `uname -r`
> 
>     ii  linux-headers-3.16.0-70-generic
> 3.16.0-70.90~14.04.1                                amd64        Linux
> kernel headers for version 3.16.0 on 64 bit x86 SMP
>     ii  linux-image-3.16.0-70-generic
> 3.16.0-70.90~14.04.1                                amd64        Linux
> kernel image for version 3.16.0 on 64 bit x86 SMP
>     ii  linux-image-3.16.0-70-generic-dbgsym
> 3.16.0-70.90~14.04.1                                amd64        Linux
> kernel debug image for version 3.16.0 on 64 bit x86 SMP
>     ii  linux-image-extra-3.16.0-70-generic
> 3.16.0-70.90~14.04.1                                amd64        Linux
> kernel extra modules for version 3.16.0 on 64 bit x86 SMP
>     ii  linux-signed-image-3.16.0-70-generic
> 3.16.0-70.90~14.04.1                                amd64
> Signed kernel image generic
> 
> 
>     # sudo cat /proc/kallsyms | grep __tracepoint_sched_process_fork
>     ffffffff81cecbe0 D __tracepoint_sched_process_fork

Yes, the tracepoints symbols do exist, but they lack EXPORT_SYMBOL, so
modules are not able to directly access them.

> Think you for pay attention to my puzzled.
>